Comparative permeability studies with radioactive and nonradioactive risedronate sodium from self-microemulsifying drug delivery system and solution.

PubMed

Ilem-Ozdemir, Derya; Gundogdu, Evren; Ekinci, Meliha; Ozgenc, Emre; Asikoglu, Makbule

2015-01-01

The purpose of this work is to prepare a self-microemulsifying drug delivery system (SMEDDS) for risedronate sodium (RSD) and to compare the permeability with RSD solution. The solubility of RSD was determined in different vehicles. Phase diagrams were constructed to determine the optimum concentration of oil, surfactant, and cosurfactant. RSD SMEDDS was prepared by using a mixture of soybean oil, cremophor EL, span 80, and transcutol (2.02:7.72:23.27:61.74, w/w, respectively). The prepared RSD SMEDDS was characterized by droplet size value. In vitro Caco-2 cell permeability studies were performed for SMEDDS and solution of radioactive ((99 m)Tc-labeled RSD) and nonradioactive RSD. The experimental results indicated that RSD SMEDDS has good stability and its droplet size is between 216.68 ± 3.79 and 225.26 ± 7.65 during stability time. In addition, RSD SMEDDS has higher permeability value than the RSD solution for both radioactive and nonradioactive experiments. The results illustrated the potential use of SMEDDS for delivery of poorly absorbed RSD.

Analytical Parameters of an Amperometric Glucose Biosensor for Fast Analysis in Food Samples.

PubMed

Artigues, Margalida; Abellà, Jordi; Colominas, Sergi

2017-11-14

Amperometric biosensors based on the use of glucose oxidase (GOx) are able to combine the robustness of electrochemical techniques with the specificity of biological recognition processes. However, very little information can be found in literature about the fundamental analytical parameters of these sensors. In this work, the analytical behavior of an amperometric biosensor based on the immobilization of GOx using a hydrogel (Chitosan) onto highly ordered titanium dioxide nanotube arrays (TiO₂NTAs) has been evaluated. The GOx-Chitosan/TiO₂NTAs biosensor showed a sensitivity of 5.46 μA·mM -1 with a linear range from 0.3 to 1.5 mM; its fundamental analytical parameters were studied using a commercial soft drink. The obtained results proved sufficient repeatability (RSD = 1.9%), reproducibility (RSD = 2.5%), accuracy (95-105% recovery), and robustness (RSD = 3.3%). Furthermore, no significant interferences from fructose, ascorbic acid and citric acid were obtained. In addition, the storage stability was further examined, after 30 days, the GOx-Chitosan/TiO₂NTAs biosensor retained 85% of its initial current response. Finally, the glucose content of different food samples was measured using the biosensor and compared with the respective HPLC value. In the worst scenario, a deviation smaller than 10% was obtained among the 20 samples evaluated.

An Interlaboratory Evaluation of Drift Tube Ion Mobility–Mass Spectrometry Collision Cross Section Measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stow, Sarah M.; Causon, Tim J.; Zheng, Xueyun

Collision cross section (CCS) measurements resulting from ion mobility-mass spectrometry (IM-MS) experiments provide a promising orthogonal dimension of structural information in MS-based analytical separations. As with any molecular identifier, interlaboratory standardization must precede broad range integration into analytical workflows. In this study, we present a reference drift tube ion mobility mass spectrometer (DTIM-MS) where improvements on the measurement accuracy of experimental parameters influencing IM separations provide standardized drift tube, nitrogen CCS values (DTCCSN2) for over 120 unique ion species with the lowest measurement uncertainty to date. The reproducibility of these DTCCSN2 values are evaluated across three additional laboratories on amore » commercially available DTIM-MS instrument. The traditional stepped field CCS method performs with a relative standard deviation (RSD) of 0.29% for all ion species across the three additional laboratories. The calibrated single field CCS method, which is compatible with a wide range of chromatographic inlet systems, performs with an average, absolute bias of 0.54% to the standardized stepped field DTCCSN2 values on the reference system. The low RSD and biases observed in this interlaboratory study illustrate the potential of DTIM-MS for providing a molecular identifier for a broad range of discovery based analyses.« less

Pharmaceuticals in grocery market fish fillets by gas chromatography-mass spectrometry.

PubMed

Mottaleb, Musavvir Arafat; Stowe, Carly; Johnson, Daniel R; Meziani, Mohammed J; Mottaleb, M Abdul

2016-01-01

Occurrences of pharmaceuticals are evident in aquatic organisms. A reproducible gas chromatography-mass spectrometry (GC-MS) method using selected ion monitoring (SIM) has been used to determine the anti-histamine diphenhydramine (DPH), anti-anxiety diazepam (DZP), anti-seizure carbamazepine (CZP) drugs and their metabolites in grocery stores fish that were homogenized, extracted, pre-concentrated, cleaned up, and examined. Identifications of the compounds in extracts were obtained by comparing similar mass spectral features and retention properties with standards. Among nine frequently detected drugs, only DPH and DZP were observed and ranged from 0.61 to 6.21 and 1.99 to 16.57 ng/g, respectively, in fourteen fish species. These concentration values were lower than the environmental fish. Mean spike recoveries of analytes exceeded 75% with relative standard deviations (RSD)<10%. The statistically-derived method detection limits (MDLs) for nine compounds ranged from 0.13 to 5.56 ng/g. Average surrogate recoveries were 80-85% with 4-9% RSD. Copyright © 2015 Elsevier Ltd. All rights reserved.

Improved high-performance liquid chromatography (HPLC) method for qualitative and quantitative analysis of allantoin in Zea mays.

PubMed

Haghi, Ghasem; Arshi, Rohollah; Safaei, Alireza

2008-02-27

A high-performance liquid chromatography (HPLC) method for the qualitative and quantitative analysis of allantoin in silk and seed of Zea mays has been developed. Allantoin separation in crude extract was achieved using a C 18 column and phosphate buffer solution (pH 3.0) as a mobile phase at ambient temperature at a flow rate of 1.0 mL/min and detected at 210 nm. The results showed that the amount of allantoin in samples was between 14 and 271 mg/100 g of dry plant material. A comprehensive validation of the method including sensitivity, linearity, repeatability, and recovery was conducted. The calibration curve was linear over the range of 0.2-200 microg/mL with a correlation coefficient of r2>0.999. Limit of detection (LOD, S/N=3) and limit of quantification (LOQ) values of the allantoin were 0.05 and 0.2 microg/mL (1.0 and 4.0 ng) respectively. The relative standard deviation (RSD) value of the repeatability was reported within 1.2%. The average recovery of allantoin added to samples was 100.6% with RSD of 1.5%.

Ultrasensitive Biosensor for the Detection of Vibrio cholerae DNA with Polystyrene-co-acrylic Acid Composite Nanospheres

NASA Astrophysics Data System (ADS)

Rahman, Mahbubur; Heng, Lee Yook; Futra, Dedi; Ling, Tan Ling

2017-08-01

An ultrasensitive electrochemical biosensor for the determination of pathogenic Vibrio cholerae ( V. cholerae) DNA was developed based on polystyrene-co-acrylic acid (PSA) latex nanospheres-gold nanoparticles composite (PSA-AuNPs) DNA carrier matrix. Differential pulse voltammetry (DPV) using an electroactive anthraquninone oligonucleotide label was used for measuring the biosensor response. Loading of gold nanoparticles (AuNPs) on the DNA-latex particle electrode has significantly amplified the faradaic current of DNA hybridisation. Together with the use of a reported probe, the biosensor has demonstrated high sensitivity. The DNA biosensor yielded a reproducible and wide linear response range to target DNA from 1.0 × 10-21 to 1.0 × 10-8 M (relative standard deviation, RSD = 4.5%, n = 5) with a limit of detection (LOD) of 1.0 × 10-21 M ( R 2 = 0.99). The biosensor obtained satisfactory recovery values between 91 and 109% ( n = 3) for the detection of V. cholerae DNA in spiked samples and could be reused for six consecutive DNA assays with a repeatability RSD value of 5% ( n = 5). The electrochemical biosensor response was stable and maintainable at 95% of its original response up to 58 days of storage period.

Optimized determination method for trans-10-hydroxy-2-decenoic acid content in royal jelly by high-performance liquid chromatography with an internal standard.

PubMed

Zhou, Jinhui; Xue, Xiaofeng; Li, Yi; Zhang, Jinzhen; Zhao, Jing

2007-01-01

An optimized reversed-phase high-performance liquid chromatography method was developed to detect the trans-10-hydroxy-2-decenoic acid (10-HDA) content in royal jelly cream and lyophilized powder. The sample was extracted using absolute ethanol. Chromatographic separation of 10-HDA and methyl 4-hydroxybenzoate as the internal standard was performed on a Nova-pak C18 column. The average recoveries were 95.0-99.2% (n = 5) with relative standard deviation (RSD) values of 1.3-2.1% for royal jelly cream and 98.0-100.0% (n = 5) with RSD values of 1.6-3.0% for lyophilized powder, respectively. The limits of detection and quantitation were 0.5 and 1.5 mg/kg, respectively, for both royal jelly cream and lyophilized powder. The method was validated for the determination of practical royal jelly products. The concentration of 10-HDA ranged from 1.26 to 2.21% for pure royal jelly cream samples and 3.01 to 6.19% for royal jelly lyophilized powder samples. For 30 royal jelly products, the 10-HDA content varied from not detectable to 0.98%.

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of chromium in water by graphite furnace atomic absorption spectrophotometry

USGS Publications Warehouse

McLain, B.J.

1993-01-01

Graphite furnace atomic absorption spectrophotometry is a sensitive, precise, and accurate method for the determination of chromium in natural water samples. The detection limit for this analytical method is 0.4 microg/L with a working linear limit of 25.0 microg/L. The precision at the detection limit ranges from 20 to 57 percent relative standard deviation (RSD) with an improvement to 4.6 percent RSD for concentrations more than 3 microg/L. Accuracy of this method was determined for a variety of reference standards that was representative of the analytical range. The results were within the established standard deviations. Samples were spiked with known concentrations of chromium with recoveries ranging from 84 to 122 percent. In addition, a comparison of data between graphite furnace atomic absorption spectrophotometry and direct-current plasma atomic emission spectrometry resulted in suitable agreement between the two methods, with an average deviation of +/- 2.0 microg/L throughout the analytical range.

A practical method to fabricate gold substrates for surface-enhanced Raman spectroscopy.

PubMed

Tantra, Ratna; Brown, Richard J C; Milton, Martin J T; Gohil, Dipak

2008-09-01

We describe a practical method of fabricating surface-enhanced Raman spectroscopy (SERS) substrates based on dip-coating poly-L-lysine derivatized microscope slides in a gold colloidal suspension. The use of only commercially available starting materials in this preparation is particularly advantageous, aimed at both reducing time and the inconsistency associated with surface modification of substrates. The success of colloid deposition has been demonstrated by scanning electron microscopy (SEM) and the corresponding SERS response (giving performance comparable to the corresponding traditional colloidal SERS substrates). Reproducibility was evaluated by conducting replicate measurements across six different locations on the substrate and assessing the extent of the variability (standard deviation values of spectral parameters: peak width and height), in response to either Rhodamine 6G or Isoniazid. Of particular interest is the observation of how some peaks in a given spectrum are more susceptible to data variability than others. For example, in a Rhodamine 6G SERS spectrum, spectral parameters of the peak at 775 cm(-1) were shown to have a relative standard deviation (RSD) % of <10%, while the peak at 1573 cm(-1) has a RSD of >or=10%. This observation is best explained by taking into account spectral variations that arise from the effect of a chemisorption process and the local nature of chemical enhancement mechanisms, which affects the enhancement of some spectral peaks but not others (analogous to resonant Raman phenomenon).

Analytical Parameters of an Amperometric Glucose Biosensor for Fast Analysis in Food Samples

PubMed Central

2017-01-01

Amperometric biosensors based on the use of glucose oxidase (GOx) are able to combine the robustness of electrochemical techniques with the specificity of biological recognition processes. However, very little information can be found in literature about the fundamental analytical parameters of these sensors. In this work, the analytical behavior of an amperometric biosensor based on the immobilization of GOx using a hydrogel (Chitosan) onto highly ordered titanium dioxide nanotube arrays (TiO2NTAs) has been evaluated. The GOx–Chitosan/TiO2NTAs biosensor showed a sensitivity of 5.46 μA·mM−1 with a linear range from 0.3 to 1.5 mM; its fundamental analytical parameters were studied using a commercial soft drink. The obtained results proved sufficient repeatability (RSD = 1.9%), reproducibility (RSD = 2.5%), accuracy (95–105% recovery), and robustness (RSD = 3.3%). Furthermore, no significant interferences from fructose, ascorbic acid and citric acid were obtained. In addition, the storage stability was further examined, after 30 days, the GOx–Chitosan/TiO2NTAs biosensor retained 85% of its initial current response. Finally, the glucose content of different food samples was measured using the biosensor and compared with the respective HPLC value. In the worst scenario, a deviation smaller than 10% was obtained among the 20 samples evaluated. PMID:29135931

Analysis of total copper, cadmium and lead in refuse-derived fuels (RDF): study on analytical errors using synthetic samples.

PubMed

Skutan, Stefan; Aschenbrenner, Philipp

2012-12-01

Components with extraordinarily high analyte contents, for example copper metal from wires or plastics stabilized with heavy metal compounds, are presumed to be a crucial source of errors in refuse-derived fuel (RDF) analysis. In order to study the error generation of those 'analyte carrier components', synthetic samples spiked with defined amounts of carrier materials were mixed, milled in a high speed rotor mill to particle sizes <1 mm, <0.5 mm and <0.2 mm, respectively, and analyzed repeatedly. Copper (Cu) metal and brass were used as Cu carriers, three kinds of polyvinylchloride (PVC) materials as lead (Pb) and cadmium (Cd) carriers, and paper and polyethylene as bulk components. In most cases, samples <0.2 mm delivered good recovery rates (rec), and low or moderate relative standard deviations (rsd), i.e. metallic Cu 87-91% rec, 14-35% rsd, Cd from flexible PVC yellow 90-92% rec, 8-10% rsd and Pb from rigid PVC 92-96% rec, 3-4% rsd. Cu from brass was overestimated (138-150% rec, 13-42% rsd), Cd from flexible PVC grey underestimated (72-75% rec, 4-7% rsd) in <0.2 mm samples. Samples <0.5 mm and <1 mm spiked with Cu or brass produced errors of up to 220% rsd (<0.5 mm) and 370% rsd (<1 mm). In the case of Pb from rigid PVC, poor recoveries (54-75%) were observed in spite of moderate variations (rsd 11-29%). In conclusion, time-consuming milling to <0.2 mm can reduce variation to acceptable levels, even given the presence of analyte carrier materials. Yet, the sources of systematic errors observed (likely segregation effects) remain uncertain.

[Development and validation of an HPLC method for the quantification of vitamin A in human milk. Its application to a rural population in Argentina].

PubMed

López, Laura B; Baroni, Andrea V; Rodríguez, Viviana G; Greco, Carola B; de Costa, Sara Macías; de Ferrer, Patricia Ronayne; Rodríguez de Pece, Silvia

2005-06-01

A methodology for the quantification of vitamin A in human milk was developed and validated. Vitamin A levels were assessed in 223 samples corresponding to the 5th, 6th and 7th postpartum months, obtained in the province of Santiago del Estero, Argentina. The samples (500 microL) were saponified with potassium hydroxide/ethanol, extracted with hexane, evaporated to dryness and reconstituted with methanol. A column RP-C18, a mobile phase methanol/water (91:9 v/v) and a fluorescence detector (lambda excitation 330 nm and lambda emition 470 nm) were used for the separation and quantification of vitamin A. The analytical parameters of linearity (r2: 0.9995), detection (0.010 microg/mL) and quantification (0.025 microg/mL) limits, precision of the method (relative standard deviation, RSD = 9.0% within a day and RSD = 8.9% among days) and accuracy (recovery = 83.8%) demonstrate that the developed method allows the quantification of vitamin A in an efficient way. The mean values + standard deviation (SD) obtained for the analyzed samples were 0.60 +/- 0.32; 0.65 +/- 0.33 and 0.61 +/- 0.26 microg/ mL for the 5th, 6th and 7th postpartum months, respectively. There were no significant differences among the three months studied and the values found were similar to those in the literature. Considering the whole population under study, 19.3% showed vitamin A levels less than 0.40 microg/mL, which represents a risk to the children in this group since at least 0.50 microg/mL are necessary to meet the infant daily needs.

40 CFR 86.1306-07 - Equipment required and specifications; overview.

Code of Federal Regulations, 2010 CFR

2010-07-01

... alternate and reference averages; these are Asd and Rsd respectively. Asd must be less than or equal to Rsd. If Asd is greater than Rsd, the Administrator will not approve the application. (D) For an unpaired comparison, calculate the t-value: tunpaired = (Aavg−Ravg)/((Asd 2+Rsd 2)/n)1/2 (E) For a paired comparison...

40 CFR 86.1306-07 - Equipment required and specifications; overview.

Code of Federal Regulations, 2013 CFR

2013-07-01

... alternate and reference averages; these are Asd and Rsd respectively. Asd must be less than or equal to Rsd. If Asd is greater than Rsd, the Administrator will not approve the application. (D) For an unpaired comparison, calculate the t-value: tunpaired = (Aavg−Ravg)/((Asd 2+Rsd 2)/n)1/2 (E) For a paired comparison...

40 CFR 86.1306-07 - Equipment required and specifications; overview.

Code of Federal Regulations, 2012 CFR

2012-07-01

... alternate and reference averages; these are Asd and Rsd respectively. Asd must be less than or equal to Rsd. If Asd is greater than Rsd, the Administrator will not approve the application. (D) For an unpaired comparison, calculate the t-value: tunpaired = (Aavg−Ravg)/((Asd 2+Rsd 2)/n)1/2 (E) For a paired comparison...

40 CFR 86.1306-07 - Equipment required and specifications; overview.

Code of Federal Regulations, 2011 CFR

2011-07-01

... alternate and reference averages; these are Asd and Rsd respectively. Asd must be less than or equal to Rsd. If Asd is greater than Rsd, the Administrator will not approve the application. (D) For an unpaired comparison, calculate the t-value: tunpaired = (Aavg−Ravg)/((Asd 2+Rsd 2)/n)1/2 (E) For a paired comparison...

A chemiluminescence biosensor for the detection of thrombin based on the aptamer composites

NASA Astrophysics Data System (ADS)

Lin, Yanna; Li, Jianbo; Wang, Yanhui; Sun, Yuanling; Ding, Chaofan; Sun, Weiyan; Luo, Chuannan

2018-03-01

An efficient, rapid, simple and ultrasensitive chemiluminescence (CL) approach was proposed for thrombin detection based on the aptamer-thrombin recognition. The aptamer composites were synthesized in this work using graphene oxide (GO) as the backing material. The thrombin was adsorbed on the aptamer composites based on the aptamer-thrombin recognition. Thus, thrombin could be quantified by the difference value of the CL intensity between supernate of the sample and the mixture which composed of thrombin and coexisted substances. The CL intensity exhibits a stable response to thrombin over a concentration range from 2.5 × 10- 10 to 1 × 10- 9 mol·L- 1 with a detection limit as low as 8.3 × 10- 11 mol·L- 1, the relative standard deviation (RSD) was found to be 4.9% for 11 determinations of 1.25 × 10- 9 mol·L- 1 thrombin. Finally, the applicability of the method was verified by applying to serum samples. The recoveries were in the range of 90.3-101.0% with RSD of 2.6-3.2%.

Determination of Five Chemical Markers in DF Formula, the Herbal Composition of Ephedra intermedia, Rheum palmatum, and Lithospermum erythrorhizon, Using High-performance Liquid Chromatography-ultraviolet Detection.

PubMed

Jeong, Birang; Roh, Jong Seong; Yoon, Michung; Yoon, Yoosik; Shin, Soon Shik; Cho, Hyun Joo; Kwon, Yong Soo; Yang, Heejung

2018-01-01

DF formula is a herbal preparation comprised three medicinal herbs, namely, Ephedra intermedia , Rheum palmatum , and Lithospermum erythrorhizon , which is being used for the treatment of obesity and liver fibrosis in Korean local clinics. Since the abovementioned three herbs exist with different proportions in DF formula and their chemical markers have different physiochemical properties; it is quite challenging to develop an analytical methodology for the determination of these chemical markers. For the analysis of the three herbs, five chemicals, (+)-pseudoephedrine (1) and (-)-ephedrine (2) for E. intermedia , aloe-emodin (3), and chrysophanol (4) for R. palmatum , and shikonin (5) for L. erythrorhizon , were selected for method validation of DF formula, and the analytical conditions were optimized and validated using high-performance liquid chromatography coupled with an ultraviolet detector (HPLC-UV). The specificities for the five compounds 1-5 were determined by their UV absorption spectra (1-4: 215 nm and 5: 520 nm). Their calibration curves showed good linear regressions with high correlation coefficient values ( R 2 > 0.9997). The limits of detection of these five markers were in the range 0.4-2.1 ng/mL, with the exception of 5 (12.7 ng/mL). The intraday variability for all the chemical markers was less than a Relative standard deviation (RSD) of 3%, except for 5 (RSD = 12.6%). In the case of interday analysis, 1 (1.0%), 2 (3.1%), and 4 (3.7%) showed much lower variabilities (RSD < 5%) than 3 (7.6%) and 5 (8.2%). Moreover, the five chemical markers showed good recoveries with good accuracies in the range of 90%-110%. The developed HPLC-UV method for the determination of the five chemical markers of the components of DF formula was validated. DF formula, the herbal composition of Ephedra intermedia , Rheum palmatum and Lithospermum erythrorhizon Five chemical markers in DF formula were (+)-pseudoephedrine (1) and (-)-ephedrine (2) for E. intermedia , aloe-emodin (3) and chrysopanol (4) for R. palmatum , and shikonin (5) for L. erythrorhizon , with quite different physico-chemical propertiesFive chemical markers in DF formula were determined by HPLC-UV Abbreviations used: EP: (-)-ephedrine; PSEP: (+)-pseudoephedrine; HPLC: High-performance liquid chromatography; UV: Ultraviolet; LOD: Limit of detection; LOQ: Limit of quantification; RSD: Relative standard deviation.

Rapid planar chromatographic analysis of 25 water-soluble dyes used as food additives.

PubMed

Morlock, Gertrud E; Oellig, Claudia

2009-01-01

A rapid planar chromatographic method for identification and quantification of 25 water-soluble dyes in food was developed. In a horizontal developing chamber, the chromatographic separation on silica gel 60F254 high-performance thin-layer chromatography plates took 12 min for 40 runs in parallel, using 8 mL ethyl acetate-methanol-water-acetic acid (65 + 23 + 11 + 1, v/v/v/v) mobile phase up to a migration distance of 50 mm. However, the total analysis time, inclusive of application and evaluation, took 60 min for 40 runs. Thus, the overall time/run can be calculated as 1.5 min with a solvent consumption of 200 microL. A sample throughput of 1000 runs/8 h day can be reached by switching between the working stations (application, development, and evaluation) in a 20 min interval, which triples the analysis throughput. Densitometry was performed by absorption measurement using the multiwavelength scan mode in the UV and visible ranges. Repeatabilities [relative standard deviation (RSD), 4 determinations] at the first or second calibration level showed precisions of mostly < or = 2.7%, ranging between 0.2 and 5.2%. Correlation coefficient values (R > or = 0.9987) and RSD values (< or = 4.2%) of the calibration curves were highly satisfactory using classical quantification. However, digital evaluation of the plate image was also used for quantification, which resulted in RSD values of the calibration curves of mostly < or = 3.0%, except for two < or = 6.0%. The method was applied for the analysis of some energy drinks and bakery ink formulations, directly applied after dilution. By recording of absorbance spectra in the visible range, the identities of the dyes found in the samples were ascertained by comparison with the respective standard bands (correlation coefficients > or = 0.9996). If necessary for confirmation, online mass spectra were recorded within a minute.

Langevin equation with fluctuating diffusivity: A two-state model

NASA Astrophysics Data System (ADS)

Miyaguchi, Tomoshige; Akimoto, Takuma; Yamamoto, Eiji

2016-07-01

Recently, anomalous subdiffusion, aging, and scatter of the diffusion coefficient have been reported in many single-particle-tracking experiments, though the origins of these behaviors are still elusive. Here, as a model to describe such phenomena, we investigate a Langevin equation with diffusivity fluctuating between a fast and a slow state. Namely, the diffusivity follows a dichotomous stochastic process. We assume that the sojourn time distributions of these two states are given by power laws. It is shown that, for a nonequilibrium ensemble, the ensemble-averaged mean-square displacement (MSD) shows transient subdiffusion. In contrast, the time-averaged MSD shows normal diffusion, but an effective diffusion coefficient transiently shows aging behavior. The propagator is non-Gaussian for short time and converges to a Gaussian distribution in a long-time limit; this convergence to Gaussian is extremely slow for some parameter values. For equilibrium ensembles, both ensemble-averaged and time-averaged MSDs show only normal diffusion and thus we cannot detect any traces of the fluctuating diffusivity with these MSDs. Therefore, as an alternative approach to characterizing the fluctuating diffusivity, the relative standard deviation (RSD) of the time-averaged MSD is utilized and it is shown that the RSD exhibits slow relaxation as a signature of the long-time correlation in the fluctuating diffusivity. Furthermore, it is shown that the RSD is related to a non-Gaussian parameter of the propagator. To obtain these theoretical results, we develop a two-state renewal theory as an analytical tool.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vlah, Zvonimir; Seljak, Uroš; Okumura, Teppei

Numerical simulations show that redshift space distortions (RSD) introduce strong scale dependence in the power spectra of halos, with ten percent deviations relative to linear theory predictions even on relatively large scales (k < 0.1h/Mpc) and even in the absence of satellites (which induce Fingers-of-God, FoG, effects). If unmodeled these effects prevent one from extracting cosmological information from RSD surveys. In this paper we use Eulerian perturbation theory (PT) and Eulerian halo biasing model and apply it to the distribution function approach to RSD, in which RSD is decomposed into several correlators of density weighted velocity moments. We model eachmore » of these correlators using PT and compare the results to simulations over a wide range of halo masses and redshifts. We find that with an introduction of a physically motivated halo biasing, and using dark matter power spectra from simulations, we can reproduce the simulation results at a percent level on scales up to k ∼ 0.15h/Mpc at z = 0, without the need to have free FoG parameters in the model.« less

Repeatability Assessment by ISO 11843-7 in Quantitative HPLC for Herbal Medicines.

PubMed

Chen, Liangmian; Kotani, Akira; Hakamata, Hideki; Tsutsumi, Risa; Hayashi, Yuzuru; Wang, Zhimin; Kusu, Fumiyo

2015-01-01

We have proposed an assessment methods to estimate the measurement relative standard deviation (RSD) of chromatographic peaks in quantitative HPLC for herbal medicines by the methodology of ISO 11843 Part 7 (ISO 11843-7:2012), which provides detection limits stochastically. In quantitative HPLC with UV detection (HPLC-UV) of Scutellaria Radix for the determination of baicalin, the measurement RSD of baicalin by ISO 11843-7:2012 stochastically was within a 95% confidence interval of the statistically obtained RSD by repetitive measurements (n = 6). Thus, our findings show that it is applicable for estimating of the repeatability of HPLC-UV for determining baicalin without repeated measurements. In addition, the allowable limit of the "System repeatability" in "Liquid Chromatography" regulated in a pharmacopoeia can be obtained by the present assessment method. Moreover, the present assessment method was also successfully applied to estimate the measurement RSDs of quantitative three-channel liquid chromatography with electrochemical detection (LC-3ECD) of Chrysanthemi Flos for determining caffeoylquinic acids and flavonoids. By the present repeatability assessment method, reliable measurement RSD was obtained stochastically, and the experimental time was remarkably reduced.

Incremental Sampling Methodology (ISM) for Metallic Residues

DTIC Science & Technology

2013-08-01

Deviation (also %RSD) Sb Antimony Sn Tin Sr Strontium STD Standard Deviation ERDC TR-13-5 x SU Sampling Unit Ti Titanium UCL Upper Confidence Limit...Ce), chromium (Cr), Cu, Fe, Pb, mag- nesium (Mg), Mn, potassium (K), sodium (Na), strontium (Sr), titanium (Ti), W, zirconium (Zr), and Zn (Clausen...wastes. A proposed alternative to EPA SW 846 Method 3050. Environmental Science and Technology 23: 89 −900. Matzke, B., N. Hassig, J. Wilson, R. Gilber

Temperature-controlled ionic liquid-based ultrasound-assisted microextraction for preconcentration of trace quantity of cadmium and nickel by using organic ligand in artificial saliva extract of smokeless tobacco products

NASA Astrophysics Data System (ADS)

Arain, Sadaf Sadia; Kazi, Tasneem Gul; Arain, Asma Jabeen; Afridi, Hassan Imran; Baig, Jameel Ahmed; Brahman, Kapil Dev; Naeemullah; Arain, Salma Aslam

2015-03-01

A new approach was developed for the preconcentration of cadmium (Cd) and nickel (Ni) in artificial saliva extract of dry snuff (brown and black) products using temperature-controlled ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction (TIL-UDLLμE) followed by electrothermal atomic absorption spectrometry (ETAAS). The Cd and Ni were complexed with ammonium pyrrolidinedithiocarbamate (APDC), extracted in ionic liquid drops, 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6]. The multivariate strategy was applied to estimate the optimum values of experimental variables influence the % recovery of analytes by TIL-UDLLμE method. At optimum experimental conditions, the limit of detection (3s) were 0.05 and 0.14 μg L-1 while relative standard deviations (% RSD) were 3.97 and 3.55 for Cd and Ni respectively. After extraction, the enhancement factors (EF) were 87 and 79 for Cd and Ni, respectively. The RSD for six replicates of 10 μg L-1 Cd and Ni were 3.97% and 3.55% respectively. To validate the proposed method, certified reference material (CRM) of Virginia tobacco leaves was analyzed, and the determined values of Cd and Ni were in good agreement with the certified values. The concentration of Cd and Ni in artificial saliva extracts corresponds to 39-52% and 21-32%, respectively, of the total contents of both elements in dry brown and black snuff products.

Variability and rapid increase in body mass index during childhood are associated with adult obesity.

PubMed

Li, Shengxu; Chen, Wei; Sun, Dianjianyi; Fernandez, Camilo; Li, Jian; Kelly, Tanika; He, Jiang; Krousel-Wood, Marie; Whelton, Paul K

2015-12-01

Body mass index (BMI) in childhood predicts obesity in adults, but it is unknown whether rapid increase and variability in BMI during childhood are independent predictors of adult obesity. The study cohort consisted of 1622 Bogalusa Heart Study participants (aged 20 to 51 years at follow-up) who had been screened at least four times during childhood (aged 4-19 years). BMI rate of change during childhood for each individual was assessed by mixed models; BMI residual standard deviation (RSD) during childhoodwas used as a measure of variability. The average follow-up period was 20.9 years. One standard deviation increase in rate of change in BMI during childhood was associated with 1.39 [95% confidence interval (CI): 1.17-1.61] kg/m(2) increase in adult BMI and 2.98 (95% CI: 2.42-3.56) cm increase in adult waist circumference, independently of childhood mean BMI. Similarly, one standard deviation increase in RSD in BMI during childhood was associated with 0.46 (95% CI: 0.23-0.69) kg/m(2) increase in adult BMI and 1.42 (95% CI: 0.82-2.02) cm increase in adult waist circumference. Odds ratio for adult obesity progressively increased from the lowest to the highest quartile of BMI rate of change or RSD during childhood (P for trend < 0.05 for both). Rapid increase and greater variability in BMI during childhood appear to be independent risk factors for adult obesity. Our findings have implications for understanding body weight regulation and obesity development from childhood to adulthood. © The Author 2015; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association.

[Study of building quantitative analysis model for chlorophyll in winter wheat with reflective spectrum using MSC-ANN algorithm].

PubMed

Liang, Xue; Ji, Hai-yan; Wang, Peng-xin; Rao, Zhen-hong; Shen, Bing-hui

2010-01-01

Preprocess method of multiplicative scatter correction (MSC) was used to reject noises in the original spectra produced by the environmental physical factor effectively, then the principal components of near-infrared spectroscopy were calculated by nonlinear iterative partial least squares (NIPALS) before building the back propagation artificial neural networks method (BP-ANN), and the numbers of principal components were calculated by the method of cross validation. The calculated principal components were used as the inputs of the artificial neural networks model, and the artificial neural networks model was used to find the relation between chlorophyll in winter wheat and reflective spectrum, which can predict the content of chlorophyll in winter wheat. The correlation coefficient (r) of calibration set was 0.9604, while the standard deviation (SD) and relative standard deviation (RSD) was 0.187 and 5.18% respectively. The correlation coefficient (r) of predicted set was 0.9600, and the standard deviation (SD) and relative standard deviation (RSD) was 0.145 and 4.21% respectively. It means that the MSC-ANN algorithm can reject noises in the original spectra produced by the environmental physical factor effectively and set up an exact model to predict the contents of chlorophyll in living leaves veraciously to replace the classical method and meet the needs of fast analysis of agricultural products.

A HPLC-DAD method for the simultaneous determination of five marker components in the traditional herbal medicine Bangpungtongsung-san

PubMed Central

Weon, Jin Bae; Yang, Hye Jin; Ma, Jin Yeul; Ma, Choong Je

2011-01-01

Background: Bangpungtongsung-san, one of the traditional herbal medicines, was known to be a prescription for obesity. Objective: For the simultaneous determination of five components (paeoniflorin, 6-gingerol, decursin, geniposide, and glycyrrhizin) in Bangpungtongsung-san, a high-performance liquid chromatography with diode-array detector method was established. Materials and Methods: To develop the method, a reverse phase column, DIONEX C 18 (5 μm, 120 µ, 4.6 mm × 150 mm) was used. The mobile phase consisted of methanol and water using a gradient elution. The UV wavelength was set at 230, 240, and 254 nm. Method validation was accomplished by linearity, precision test, and recovery test. Results: All calibration curves of components showed good linearity (R 2 > 0.9959). The limit of detection (LOD) and limit of quantification (LOQ) ranged from 0.01 to 0.17 μg/ml and 0.04 to 0.53 μg/ml, respectively. The relative standard deviations (RSD) value of precision test, intraday and interday tests were less than 0.43% and 1.26%. In the recovery test, results of accuracy ranged from 95.27% to 107.70% with RSD values less than 2.21%. Conclusion: This developed method was applied to the commercial Bangpungtongsung-san sample and the five marker components were separated effectively without interference of any peaks of components. PMID:21472081

Gravimetric method for the determination of diclofenac in pharmaceutical preparations.

PubMed

Tubino, Matthieu; De Souza, Rafael L

2005-01-01

A gravimetric method for the determination of diclofenac in pharmaceutical preparations was developed. Diclofenac is precipitated from aqueous solution with copper(II) acetate in pH 5.3 (acetic acid/acetate buffer). Sample aliquots had approximately the same quantity of the drug content in tablets (50 mg) or in ampules (75 mg). The observed standard deviation was about +/- 2 mg; therefore, the relative standard deviation (RSD) was approximately 4% for tablet and 3% for ampule preparations. The results were compared with those obtained with the liquid chromatography method recommended in the United States Pharmacopoeia using the statistical Student's t-test. Complete agreement was observed. It is possible to obtain more precise results using higher aliquots, for example 200 mg, in which case the RSD falls to 1%. This gravimetric method, contrary to what is expected for this kind of procedure, is relatively fast and simple to perform. The main advantage is the absolute character of the gravimetric analysis.

Beneficial effects of renal sympathetic denervation on cardiovascular inflammation and remodeling in essential hypertension.

PubMed

Dörr, Oliver; Liebetrau, Christoph; Möllmann, Helge; Mahfoud, Felix; Ewen, Sebastian; Gaede, Luise; Troidl, Christian; Hoffmann, Jedrzej; Busch, Nikolai; Laux, Gerald; Wiebe, Jens; Bauer, Timm; Hamm, Christian; Nef, Holger

2015-02-01

Renal sympathetic denervation (RSD) represents a potential treatment option for certain patients with resistant arterial hypertension (HT). HT is associated with chronic vascular inflammation and remodeling, contributing to progressive vascular damage, and atherosclerosis. The present study aimed to evaluate the influence of RSD on cardiovascular inflammation and remodeling by determining serum levels of interleukin-6 (IL-6), high-sensitive C-reactive protein (hsCRP), matrix metalloproteinases (MMP), and tissue inhibitor of metalloproteinases (TIMP). A total of 60 consecutive patients (age 67.9 ± 9.6 years) undergoing RSD were included. A therapeutic response was defined as an office systolic blood pressure (SBP) reduction of >10 mmHg 6 months after RSD. Venous serum samples for measurement of hsCRP, IL-6, MMP-2, MMP-9, and TIMP-1 were collected prior to and 6 months after RSD. A significant reduction in office SBP of 26.4 mmHg [SBPbaseline 169.3 mmHg (SD 11.3), p < 0.001] was documented 6 months after RSD. The serum levels of hsCRP (p < 0.001) and the pro-inflammatory cytokine IL-6 (p < 0.001) were significantly decreased compared to baseline values. The levels of MMP-9 (p = 0.024) and MMP-2 (p < 0.01) were significantly increased compared to baseline values. In addition to the effective blood pressure reduction in response to RSD, this study demonstrates a positive effect of RSD on biomarkers reflecting vascular inflammation and remodeling. These results suggest a possible prognostic benefit of RSD in high-risk patients for endothelial dysfunction and cardiovascular remodeling as well as end-organ damage.

Simultaneous Determination of Multiple Ginsenosides in Panax ginseng Herbal Medicines with One Single Reference Standard.

PubMed

Wu, Chunwei; Guan, Qingxiao; Wang, Shumei; Rong, Yueying

2017-01-01

Root of Panax ginseng C. A. Mey (Renseng in Chinese) is a famous Traditional Chinese Medicine. Ginsenosides are the major bioactive components. However, the shortage and high cost of some ginsenoside reference standards make it is difficult for quality control of P. ginseng . A method, single standard for determination of multicomponents (SSDMC), was developed for the simultaneous determination of nine ginsenosides in P. ginseng (ginsenoside Rg 1 , Re, Rf, Rg 2 , Rb 1 , Rc, Rb 2 , Rb 3 , Rd). The analytes were separated on Inertsil ODS-3 C18 (250 mm × 4.6 mm, 5 μm) with gradient elution of acetonitrile and water. The flow rate was 1 mL/min and detection wavelength was set at 203 nm. The feasibility and accuracy of SSDMC were checked by the external standard method, and various high-performance liquid chromatographic (HPLC) instruments and chromatographic conditions were investigated to verify its applicability. Using ginsenoside Rg 1 as the internal reference substance, the contents of other eight ginsenosides were calculated according to conversion factors (F) by HPLC. The method was validated with linearity ( r 2 ≥ 0.9990), precision (relative standard deviation [RSD] ≤2.9%), accuracy (97.5%-100.8%, RSD ≤ 1.6%), repeatability, and stability. There was no significant difference between the SSDMC method and the external standard method. New SSDMC method could be considered as an ideal mean to analyze the components for which reference standards are not readily available. A method, single standard for determination of multicomponents (SSDMC), was established by high-performance liquid chromatography for the simultaneous determination of nine ginsenosides in Panax ginseng (ginsenoside Rg1, Re, Rf, Rg2, Rb1, Rc, Rb2, Rb3, Rd)Various chromatographic conditions were investigated to verify applicability of FsThe feasibility and accuracy of SSDMC were checked by the external standard method. Abbreviations used: DRT: Different value of retention time; F: Conversion factor; HPLC: High-performance Liquid Chromatography; LOD: Limit of detection; LOQ: Limit of quantitation; PD: Percent difference; PPD: 20(S)-protopanaxadiol; PPT: 20(S)-protopanaxatriol; RSD: Relative standard deviation; SSDMC: Single Standard for Determination of Multicomponents; TCM: Traditional Chinese Medicine.

Determination of Five Chemical Markers in DF Formula, the Herbal Composition of Ephedra intermedia, Rheum palmatum, and Lithospermum erythrorhizon, Using High-performance Liquid Chromatography-ultraviolet Detection

PubMed Central

Jeong, Birang; Roh, Jong Seong; Yoon, Michung; Yoon, Yoosik; Shin, Soon Shik; Cho, Hyun Joo; Kwon, Yong Soo; Yang, Heejung

2018-01-01

Background: DF formula is a herbal preparation comprised three medicinal herbs, namely, Ephedra intermedia, Rheum palmatum, and Lithospermum erythrorhizon, which is being used for the treatment of obesity and liver fibrosis in Korean local clinics. Objective: Since the abovementioned three herbs exist with different proportions in DF formula and their chemical markers have different physiochemical properties; it is quite challenging to develop an analytical methodology for the determination of these chemical markers. Materials and Methods: For the analysis of the three herbs, five chemicals, (+)-pseudoephedrine (1) and (−)-ephedrine (2) for E. intermedia, aloe-emodin (3), and chrysophanol (4) for R. palmatum, and shikonin (5) for L. erythrorhizon, were selected for method validation of DF formula, and the analytical conditions were optimized and validated using high-performance liquid chromatography coupled with an ultraviolet detector (HPLC-UV). Results: The specificities for the five compounds 1–5 were determined by their UV absorption spectra (1–4: 215 nm and 5: 520 nm). Their calibration curves showed good linear regressions with high correlation coefficient values (R2 > 0.9997). The limits of detection of these five markers were in the range 0.4–2.1 ng/mL, with the exception of 5 (12.7 ng/mL). The intraday variability for all the chemical markers was less than a Relative standard deviation (RSD) of 3%, except for 5 (RSD = 12.6%). In the case of interday analysis, 1 (1.0%), 2 (3.1%), and 4 (3.7%) showed much lower variabilities (RSD < 5%) than 3 (7.6%) and 5 (8.2%). Moreover, the five chemical markers showed good recoveries with good accuracies in the range of 90%–110%. Conclusions: The developed HPLC-UV method for the determination of the five chemical markers of the components of DF formula was validated. SUMMARY DF formula, the herbal composition of Ephedra intermedia, Rheum palmatum and Lithospermum erythrorhizonFive chemical markers in DF formula were (+)-pseudoephedrine (1) and (-)-ephedrine (2) for E. intermedia, aloe-emodin (3) and chrysopanol (4) for R. palmatum, and shikonin (5) for L. erythrorhizon, with quite different physico-chemical propertiesFive chemical markers in DF formula were determined by HPLC-UV Abbreviations used: EP: (−)-ephedrine; PSEP: (+)-pseudoephedrine; HPLC: High-performance liquid chromatography; UV: Ultraviolet; LOD: Limit of detection; LOQ: Limit of quantification; RSD: Relative standard deviation. PMID:29720825

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shekhar, R.; Karunasagar, D.; Ranjit, M.

An open-to-air type electrolyte cathode discharge (ELCAD) has been developed with a new design. The present configuration leads to a stable plasma even at low flow rates (0.96 mL/min). Plasma fluctuations arising from the variations in the gap between solid anode and liquid cathode were eliminated by providing a V-groove to the liquid glass-capillary. Cathode (ground) connection is given to the solution at the V-groove itself. Interfaced to atomic emission spectrometry (AES), its analytical performance is evaluated. The optimized molarity of the solution is 0.2 M. The analytical response curves for Ca, Cu, Cd, Pb, Hg, Fe, and Zn demonstratedmore » good linearity. The limit of detections of Ca, Cu, Cd, Pb, Hg, Fe, and Zn are determined to be 17, 11, 5, 45, 15, 28, and 3 ng mL{sup -1}. At an integration time of 0.3 s, the relative standard deviation (RSD) values of the acid blank solutions are found to be less than 10% for the elements Ca, Cu, Cd, Hg, Fe, and Zn and 18% for Pb. The method is applied for the determination of the elemental constituents in different matrix materials such as tuna fish (IAEA-350), oyster tissue (NIST SRM 1566a), and coal fly ash (CFA SRM 1633b). The obtained results are in good agreement with the certified values. The accuracy is found to be between 7% and 0.6% for major to trace levels of constituent elements and the precision between 11% and 0.6%. For the injection of 100 {mu} L of 200 ng mL{sup -1} mercury solution at the flow rate of 0.8 mL/min, the flow injection studies resulted in the relative standard deviation (RSD) of 8%, concentration detection limit of 10 ng/mL, and mass detection limit of 1 ng for mercury.« less

Simultaneous determination of atenolol and amlodipine in tablets by high-performance thin-layer chromatography.

PubMed

Argekar, A P; Powar, S G

2000-01-01

A new simple, precise, rapid and selective high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous determination of atenolol (ATL) and amlodipine (AMLO) in tablets, using methylene chloride:methanol:ammonia solution (25% NH3) (8.8:1.3:0.1; v/v) as the mobile phase and Merck HPTLC plates (0.2 mm thickness) precoated with 60F254 silica gel on aluminium sheet as the stationary phase. Detection was carried out densitometrically using a UV detector at 230 nm. The retention factors of ATL and AMLO were 0.33 and 0.75, respectively. Calibration curves were linear in the range 10-500 microg ml(-1) for both. Assays of ATL and AMLO were 49.87 mg per tablet (relative standard deviation (R.S.D.), 1.3%) and 4.90 mg per tablet (R.S.D., 1.38%) for brand I, and 49.27 mg per tablet (R.S.D., 1.12%) and 4.98 mg per tablet (R.S.D., 1.42%) for brand II, respectively. The percentage recoveries for ATL and AMLO for brands I and II were 99.06 and 99.30%, and 99.27 and 99.15%, respectively.

Quantification of almond skin polyphenols by liquid chromatography-mass spectrometry.

PubMed

Bolling, Bradley W; Dolnikowski, Gregory; Blumberg, Jeffrey B; Oliver Chen, C Y

2009-01-01

Reverse phase HPLC coupled to negative mode electrospray ionization (ESI) mass spectrometry (MS) was used to quantify 16 flavonoids and 2 phenolic acids from almond skin extracts. Calibration curves of standard compounds were run daily and daidzein was used as an internal standard. The inter-day relative standard deviation (RSD) of standard curve slopes ranged from 13% to 25% of the mean. On column (OC) limits of detection (LOD) for polyphenols ranged from 0.013 to 1.4 pmol, and flavonoid glycosides had a 7-fold greater sensitivity than aglycones. Limits of quantification were 0.043 to 2.7 pmol OC, with a mean of 0.58 pmol flavonoid OC. Mean inter-day RSD of polyphenols in almond skin extract was 6.8% with a range of 4% to 11%, and intra-day RSD was 2.4%. Liquid nitrogen (LN(2)) or hot water (HW) blanching was used to facilitate removal of the almond skins prior to extraction using assisted solvent extraction (ASE) or steeping with acidified aqueous methanol. Recovery of polyphenols was greatest in HW blanched almond extracts with a mean value of 2.1 mg/g skin. ASE and steeping extracted equivalent polyphenols, although ASE of LN(2) blanched skins yielded 52% more aglycones and 23% less flavonoid glycosides. However, the extraction methods did not alter flavonoid profile of HW blanched almond skins. The recovery of polyphenolic components that were spiked into almond skins before the steeping extraction was 97% on a mass basis. This LC-MS method presents a reliable means of quantifying almond polyphenols.

Quantification of Almond Skin Polyphenols by Liquid Chromatography-Mass Spectrometry

PubMed Central

Bolling, Bradley W.; Dolnikowski, Gregory; Blumberg, Jeffrey B.; Oliver Chen, C.Y.

2014-01-01

Reverse phase HPLC coupled to negative mode electrospray ionization (ESI) mass spectrometry (MS) was used to quantify 16 flavonoids and 2 phenolic acids from almond skin extracts. Calibration curves of standard compounds were run daily and daidzein was used as an internal standard. The inter-day relative standard deviation (RSD) of standard curve slopes ranged from 13% to 25% of the mean. On column (OC) limits of detection (LOD) for polyphenols ranged from 0.013 to 1.4 pmol, and flavonoid glycosides had a 7-fold greater sensitivity than aglycones. Limits of quantification were 0.043 to 2.7 pmol OC, with a mean of 0.58 pmol flavonoid OC. Mean inter-day RSD of polyphenols in almond skin extract was 6.8% with a range of 4% to 11%, and intra-day RSD was 2.4%. Liquid nitrogen (LN2) or hot water (HW) blanching was used to facilitate removal of the almond skins prior to extraction using assisted solvent extraction (ASE) or steeping with acidified aqueous methanol. Recovery of polyphenols was greatest in HW blanched almond extracts with a mean value of 2.1 mg/g skin. ASE and steeping extracted equivalent polyphenols, although ASE of LN2 blanched skins yielded 52% more aglycones and 23% less flavonoid glycosides. However, the extraction methods did not alter flavonoid profile of HW blanched almond skins. The recovery of polyphenolic components that were spiked into almond skins before the steeping extraction was 97% on a mass basis. This LC-MS method presents a reliable means of quantifying almond polyphenols. PMID:19490319

Inductively coupled plasma mass spectrometry with a twin quadrupole instrument using laser ablation sample introduction and monodisperse dried microparticulate injection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allen, Lloyd A.

1996-10-17

The focus of this dissertation is the use of a twin quadrupole inductively coupled plasma mass spectrometer (ICP-MS) for the simultaneous detection of two m/z values. The twin quadrupole ICP-MS is used with laser ablation sample introduction in both the steady state (10 Hz) and single pulse modes. Steady state signals are highly correlated and the majority of flicker noise cancels when the ratio is calculated. Using a copper sample, the isotope ratio 63Cu +/ 65Cu + is measured with a relative standard deviation (RSD) of 0.26%. Transient signals for single laser pulses are also obtained. Copper isotope ratio measurementsmore » for several laser pulses are measured with an RSD of 0.85%. Laser ablation (LA) is used with steel samples to assess the ability of the twin quadrupole ICP-MS to eliminate flicker noise of minor components of steel samples. Isotopic and internal standard ratios are measured in the first part of this work. The isotope ratio 52Cr +/ 53Cr + (Cr present at 1.31 %) can be measured with an RSD of 0.06 % to 0.1 %. For internal standard elements, RSDs improve from 1.9 % in the Cr + signal to 0.12% for the ratio of 51V + to 52Cr +. In the second part of this work, one mass spectrometer is scanned while the second channel measures an individual m/z value. When the ratio of these two signals is calculated, the peak shapes in the mass spectrum are improved significantly. Pulses of analyte and matrix ions from individual drops are measured simultaneously using the twin quadrupole ICP-MS with monodisperse dried microparticulate injection (MDMI). At modest Pb concentrations (500 ppm), a shoulder on the leading edge of the Li + signal becomes apparent. Space charge effects are consistent with the disturbances seen.« less

Liquid paraffin as new dilution medium for the analysis of high boiling point residual solvents with static headspace-gas chromatography.

PubMed

D'Autry, Ward; Zheng, Chao; Bugalama, John; Wolfs, Kris; Hoogmartens, Jos; Adams, Erwin; Wang, Bochu; Van Schepdael, Ann

2011-07-15

Residual solvents are volatile organic compounds which can be present in pharmaceutical substances. A generic static headspace-gas chromatography analysis method for the identification and control of residual solvents is described in the European Pharmacopoeia. Although this method is proved to be suitable for the majority of samples and residual solvents, the method may lack sensitivity for high boiling point residual solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide and benzyl alcohol. In this study, liquid paraffin was investigated as new dilution medium for the analysis of these residual solvents. The headspace-gas chromatography method was developed and optimized taking the official Pharmacopoeia method as a starting point. The optimized method was validated according to ICH criteria. It was found that the detection limits were below 1μg/vial for each compound, indicating a drastically increased sensitivity compared to the Pharmacopoeia method, which failed to detect the compounds at their respective limit concentrations. Linearity was evaluated based on the R(2) values, which were above 0.997 for all compounds, and inspection of residual plots. Instrument and method precision were examined by calculating the relative standard deviations (RSD) of repeated analyses within the linearity and accuracy experiments, respectively. It was found that all RSD values were below 10%. Accuracy was checked by a recovery experiment at three different levels. Mean recovery values were all in the range 95-105%. Finally, the optimized method was applied to residual DMSO analysis in four different Kollicoat(®) sample batches. Copyright © 2011 Elsevier B.V. All rights reserved.

Assessment of sediment quality based on acid-volatile sulfide and simultaneously extracted metals in heavily industrialized area of Asaluyeh, Persian Gulf: concentrations, spatial distributions, and sediment bioavailability/toxicity.

PubMed

Arfaeinia, Hossein; Nabipour, Iraj; Ostovar, Afshin; Asadgol, Zahra; Abuee, Ehsan; Keshtkar, Mozhgan; Dobaradaran, Sina

2016-05-01

Sediment samples from the coastal area of Asaluyeh harbor were collected during autumn and spring 2015. The acid-volatile sulfide (AVS) and simultaneously extracted metals (SEMs) were measured to assess the sediment quality and potential ecological risks. The average concentrations (and relative standard deviation (RSD)) of AVS in the industrial sediments were 12.32 μmol/g (36.91) and 6.34 μmol/g (80.05) in autumn and spring, respectively, while in the urban area, these values were 0.44 μmol/g (123.50) and 0.31 μmol/g (160.0) in autumn and spring, respectively. The average concentrations of SEM (and RSD) in the industrial sediments were 15.02 μmol/g (14.38) and 12.34 μmol/g (20.65) in autumn and spring, respectively, while in the urban area, these values were 1.10 μmol/g (43.03) and 1.06 μmol/g (55.59) in autumn and spring, respectively. Zn was the predominant component (34.25-86.24 %) of SEM, while the corresponding value for Cd, much more toxic ingredient, was less than 1 %. Some of the coastal sediments in the harbor of Asaluyeh (20 and 47 % in autumn and spring, respectively) had expected adverse biological effects based on the suggested criterion by United States Environmental Protection Agency (USEPA), while most stations (80 and 53 % in autumn and spring, respectively) had uncertain adverse effects.

Performance evaluation of laser induced breakdown spectroscopy in the measurement of liquid and solid samples

NASA Astrophysics Data System (ADS)

Bilge, Gonca; Sezer, Banu; Boyaci, Ismail Hakki; Eseller, Kemal Efe; Berberoglu, Halil

2018-07-01

Liquid analysis by using LIBS is a complicated process due to difficulties encountered during the collection of light and formation of plasma in liquid. To avoid these, some applications are performed such as aerosol formation and transforming liquid into solid state. However, performance of LIBS in liquid samples still remains a challenging issue. In this study, performance evaluation of LIBS and parameter optimizations in liquid and solid phase samples were performed. For this purpose, milk was chosen as model sample; milk powder was used as solid sample, and milk was used as liquid sample in the experiments. Different experimental setups have been constructed for each sampling technique, and optimizations were performed to determine suitable parameters such as delay time, laser energy, repetition rate and speed of rotary table for solid sampling technique, and flow rate of carrier gas for liquid sampling technique. Target element was determined as Ca, which is a critically important element in milk for determining its nutritional value and Ca addition. In optimum parameters, limit of detection (LOD), limit of quantification (LOQ) and relative standard deviation (RSD) values were calculated as 0.11%, 0.36% and 8.29% respectively for milk powders samples; while LOD, LOQ and RSD values were calculated as 0.24%, 0.81%, and 10.93% respectively for milk samples. It can be said that LIBS is an applicable method in both liquid and solid samples with suitable systems and parameters. However, liquid analysis requires much more developed systems for more accurate results.

[Determination of Total Iron and Fe2+ in Basalt].

PubMed

Liu, Jian-xun; Chen, Mei-rong; Jian, Zheng-guo; Wu, Gang; Wu, Zhi-shen

2015-08-01

Basalt is the raw material of basalt fiber. The content of FeO and Fe2O3 has a great impact on the properties of basalt fibers. ICP-OES and dichromate method were used to test total Fe and Fe(2+) in basalt. Suitable instrument parameters and analysis lines of Fe were chosen for ICP-OES. The relative standard deviation (RSD) of ICP-OES is 2.2%, and the recovery is in the range of 98%~101%. The method shows simple, rapid and highly accurate for determination of total Fe and Fe(2+) in basalt. The RSD of ICP-OES and dichromate method is 0.42% and 1.4%, respectively.

New protocol for αAstree electronic tongue enabling full performance qualification according to ICH Q2.

PubMed

Pein, Miriam; Eckert, Carolin; Preis, Maren; Breitkreutz, Jörg

2013-09-01

Performance qualification (PQ) of taste sensing systems is mandatory for their use in pharmaceutical industry. According to ICH Q2 (R1) and a recent adaptation for taste sensing systems, non-specificity, log-linear relationships between the concentration of analytes and the sensor signal as well as a repeatability with relative standard deviation (RSD) values <4% were defined as basic requirements to pass a PQ. In the present work, the αAstree taste sensing system led to a successful PQ procedure by the use of recent sensor batches for pharmaceutical applications (sensor set #2) and a modified measurement protocol. Log-linear relationships between concentration and responses of each sensor were investigated for different bitter tasting active pharmaceutical ingredients (APIs). Using the new protocol, RSD values <2.1% were obtained in the repeatability study. Applying the visual evaluation approach, detection and quantitation limit could be determined for caffeine citrate with every sensor (LOD 0.05-0.5 mM, LOQ: 0.1-0.5 mM). In addition, the sensor set marketed for food applications (sensor set #5) was proven to show beneficial effects regarding the log-linear relationship between the concentration of quinine hydrochloride and the sensor signal. By the use of our proposed protocol, it is possible to implement the αAstree taste sensing system as a tool to assure quality control in the pharmaceutical industry. Copyright © 2013 Elsevier B.V. All rights reserved.

High-throughput quantitative analysis by desorption electrospray ionization mass spectrometry.

PubMed

Manicke, Nicholas E; Kistler, Thomas; Ifa, Demian R; Cooks, R Graham; Ouyang, Zheng

2009-02-01

A newly developed high-throughput desorption electrospray ionization (DESI) source was characterized in terms of its performance in quantitative analysis. A 96-sample array, containing pharmaceuticals in various matrices, was analyzed in a single run with a total analysis time of 3 min. These solution-phase samples were examined from a hydrophobic PTFE ink printed on glass. The quantitative accuracy, precision, and limit of detection (LOD) were characterized. Chemical background-free samples of propranolol (PRN) with PRN-d(7) as internal standard (IS) and carbamazepine (CBZ) with CBZ-d(10) as IS were examined. So were two other sample sets consisting of PRN/PRN-d(7) at varying concentration in a biological milieu of 10% urine or porcine brain total lipid extract, total lipid concentration 250 ng/microL. The background-free samples, examined in a total analysis time of 1.5 s/sample, showed good quantitative accuracy and precision, with a relative error (RE) and relative standard deviation (RSD) generally less than 3% and 5%, respectively. The samples in urine and the lipid extract required a longer analysis time (2.5 s/sample) and showed RSD values of around 10% for the samples in urine and 4% for the lipid extract samples and RE values of less than 3% for both sets. The LOD for PRN and CBZ when analyzed without chemical background was 10 and 30 fmol, respectively. The LOD of PRN increased to 400 fmol analyzed in 10% urine, and 200 fmol when analyzed in the brain lipid extract.

[Beneficial effects of renal denervation on pulmonary vascular remodeling in experimental pulmonary artery hypertension].

PubMed

Zhang, Shujuan; Zhao, Qingyan; Jiang, Xuejun; Yang, Bo; Dai, Zixuan; Wang, Xiaozhan; Wang, Xule; Guo, Zongwen; Yu, Shengbo; Tang, Yanhong; Hu, Wei; Huang, Congxin

2015-04-14

To explore the effects of renal sympathetic denervation (RSD) on pulmonary vascular remodeling in a model of pulmonary arterial hypertension (PAH). According to the random number table, 24 beagles were randomized into control, PAH and PAH+RSD groups (n=8 each). The levels of neurohormone, echocardiogram and dynamics parameters were measured. Then 0.1 ml/kg dimethylformamide (control group) or 2 mg/kg dehydromonocrotaline (PAH and PAH+RSD groups) were injected. The PAH+RSD group underwent RSD after injection. At week 8 post-injection, the neurohormone levels, echocardiogram, dynamics parameters and pulmonary tissue morphology were observed. The values of right ventricular systolic pressure (RVSP) and pulmonary arterial systolic pressure (PASP) in PAH and PAH+RSD groups were both significantly higher than those in control group ((42.8±8.7), (30.8±6.8) vs (23.2±5.7) mmHg (1 mmHg=0.133 kPa) and (45.1±11.2), (32.6±7.9) vs (24.7±7.1) mmHg). Meanwhile, the values of RVSP and PASP in PAH group were higher than those in PAH+RSD group (all P<0.01). The levels of serum angiotensin II (Ang II) and endothelin-1 significantly increased after 8 weeks in PAH dogs ((228±41) vs (113±34) pg/ml and (135±15) vs (77±7) pg/ml, all P<0.01). And Ang II and endothelin-1 were higher in lung tissues of PAH group ((65±10) and (96±10) pg/ml) than in those of control group ((38±7) and (54±6) pg/ml) and PAH+RSD group ((46±8) and (67±9) pg/ml) (all P<0.01). Pulmonary tissues had marked collagen hyperplasia and lamellar corpuscles of type 2 alveolar cells were damaged more severely in PAH dogs than in PAH+RSD dogs. RSD suppresses pulmonary vascular remodeling and decreases pulmonary arterial pressure in experimental PAH. And the effect of RSD on PAH may contribute to decreased neurohormone levels.

Multivessel supercritical fluid extraction of food items in Total Diet Study.

PubMed

Hopper, M L; King, J W; Johnson, J H; Serino, A A; Butler, R J

1995-01-01

An off-line, large capacity, multivessel supercritical fluid extractor (SFE) was designed and constructed for extraction of large samples. The extractor can simultaneously process 1-6 samples (15-25 g) by using supercritical carbon dioxide (SC-CO2), which is relatively nontoxic and nonflammable, as the solvent extraction medium. Lipid recoveries for the SFE system were comparable to those obtained by blending or Soxhlet extraction procedures. Extractions at 10,000 psi, 80 degrees C, expanded gaseous CO2 flow rates of 4-5 L/min (35 degrees C), and 1-3 h extraction times gave reproducible lipid recoveries for pork sausage (relative standard deviation [RSD], 1.32%), corn chips (RSD, 0.46%), cheddar cheese (RSD, 1.14%), and peanut butter (RSD, 0.44%). In addition, this SFE system gave reproducible recoveries (> 93%) for butter fortified with cis-chlordane and malathion at the 100 ppm and 0.1 ppm levels. Six portions each of cheddar cheese, saltine crackers, sandwich cookies, and ground hamburger also were simultaneously extracted with SC-CO2 and analyzed for incurred pesticide residues. Results obtained with this SFE system were reproducible and comparable with results from organic-solvent extraction procedures currently used in the Total Diet Study; therefore, use and disposal of large quantities of organic solvents can be eliminated.

Determination of saponins and flavonoids in ivy leaf extracts using HPLC-DAD.

PubMed

Yu, Miao; Shin, Young June; Kim, Nanyoung; Yoo, Guijae; Park, SeonJu; Kim, Seung Hyun

2015-04-01

A new method for the determination of six compounds, chlorogenic acid, rutin, nicotiflorin, hederacoside C, hederasaponin B and α-hederin, in ivy leaf extracts using high-performance liquid chromatography with diode array detector was developed. The chromatographic separation was performed on a YMC Hydrosphere C18 analytical column using a gradient elution of 0.1% phosphoric acid and acetonitrile. The method was validated in terms of specificity, linearity (r(2) > 0.9999), precision [relative standard deviation (RSD) < 0.36%] and accuracy (97.4-103.8%). The limit of detection and limit of quantification were <20.32 and 61.56 ng for all analytes, respectively. The tested compounds were found to be stable in the ivy leaf extract from 0 to 48 h, and the RSD value for each compound was <0.90%. The validated method was successfully applied to quantify all six compounds in a 30% ethanol ivy leaf extract and 13 ivy leaf extract products. The results showed that all the tested products satisfied the minimum requirement for the content of hederacoside C. However, there were some differences between the contents of other constituents. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

An IC-MS/MS Method for the Determination of 1-Hydroxyethylidene-1,1-diphosphonic Acid on Uncooked Foods Treated with Peracetic Acid-Based Sanitizers.

PubMed

Suzuki, Ippei; Kubota, Hiroki; Ohtsuki, Takashi; Tatebe, Chiye; Tada, Atsuko; Yano, Takeo; Akiyama, Hiroshi; Sato, Kyoko

2016-01-01

A rapid, sensitive, and specific analytical method for the determination of 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) on uncooked foods after treatment with a peracetic acid-based sanitizer (PAS) was developed. The method involves simple sample preparation steps and analysis using ion chromatography (IC) coupled with tandem mass spectrometry (MS/MS). The quantification limits of HEDP on uncooked foods are 0.007 mg/kg for vegetables and fruits and 0.2 mg/kg for meats. The recovery and relative standard deviation (RSD) of HEDP analyses of uncooked foods ranged from 73.9 to 103.8% and 1.9 to 12.6%, respectively. The method's accuracy and precision were evaluated by inter-day recovery tests. The recovery for all samples ranged from 93.6 to 101.2%, and the within-laboratory repeatability and reproducibility were evaluated based on RSD values, which were less than 6.9 and 11.5%, respectively. Analyses of PAS-treated fruits and vegetables using the developed method indicated levels of HEDP ranging from 0.008 to 0.351 mg/kg. Therefore, the results of the present study suggest that the proposed method is an accurate, precise, and reliable way to determine residual HEDP levels on PAS-treated uncooked foods.

Detecting kinematic boundary surfaces in phase space: particle mass measurements in SUSY-like events

DOE PAGES

Debnath, Dipsikha; Gainer, James S.; Kilic, Can; ...

2017-06-19

We critically examine the classic endpoint method for particle mass determination, focusing on difficult corners of parameter space, where some of the measurements are not independent, while others are adversely affected by the experimental resolution. In such scenarios, mass differences can be measured relatively well, but the overall mass scale remains poorly constrained. Using the example of the standard SUSY decay chain q ~→χ ~ 0 2→ℓ ~→χ ~ 0 1 , we demonstrate that sensitivity to the remaining mass scale parameter can be recovered by measuring the two-dimensional kinematical boundary in the relevant three-dimensional phase space of invariant massesmore » squared. We develop an algorithm for detecting this boundary, which uses the geometric properties of the Voronoi tessellation of the data, and in particular, the relative standard deviation (RSD) of the volumes of the neighbors for each Voronoi cell in the tessellation. We propose a new observable, Σ¯ , which is the average RSD per unit area, calculated over the hypothesized boundary. We show that the location of the Σ¯ maximum correlates very well with the true values of the new particle masses. Our approach represents the natural extension of the one-dimensional kinematic endpoint method to the relevant three dimensions of invariant mass phase space.« less

Multivariate optimization and validation of an analytical methodology by RP-HPLC for the determination of losartan potassium in capsules.

PubMed

Bonfilio, Rudy; Tarley, César Ricardo Teixeira; Pereira, Gislaine Ribeiro; Salgado, Hérida Regina Nunes; de Araújo, Magali Benjamim

2009-11-15

This paper describes the optimization and validation of an analytical methodology for the determination of losartan potassium in capsules by HPLC using 2(5-1) fractional factorial and Doehlert designs. This multivariate approach allows a considerable improvement in chromatographic performance using fewer experiments, without additional cost for columns or other equipment. The HPLC method utilized potassium phosphate buffer (pH 6.2; 58 mmol L(-1))-acetonitrile (65:35, v/v) as the mobile phase, pumped at a flow rate of 1.0 mL min(-1). An octylsilane column (100 mm x 4.6mm i.d., 5 microm) maintained at 35 degrees C was used as the stationary phase. UV detection was performed at 254 nm. The method was validated according to the ICH guidelines, showing accuracy, precision (intra-day relative standard deviation (R.S.D.) and inter-day R.S.D values <2.0%), selectivity, robustness and linearity (r=0.9998) over a concentration range from 30 to 70 mg L(-1) of losartan potassium. The limits of detection and quantification were 0.114 and 0.420 mg L(-1), respectively. The validated method may be used to quantify losartan potassium in capsules and to determine the stability of this drug.

Detecting kinematic boundary surfaces in phase space: particle mass measurements in SUSY-like events

DOE Office of Scientific and Technical Information (OSTI.GOV)

Debnath, Dipsikha; Gainer, James S.; Kilic, Can

We critically examine the classic endpoint method for particle mass determination, focusing on difficult corners of parameter space, where some of the measurements are not independent, while others are adversely affected by the experimental resolution. In such scenarios, mass differences can be measured relatively well, but the overall mass scale remains poorly constrained. Using the example of the standard SUSY decay chain q ~→χ ~ 0 2→ℓ ~→χ ~ 0 1 , we demonstrate that sensitivity to the remaining mass scale parameter can be recovered by measuring the two-dimensional kinematical boundary in the relevant three-dimensional phase space of invariant massesmore » squared. We develop an algorithm for detecting this boundary, which uses the geometric properties of the Voronoi tessellation of the data, and in particular, the relative standard deviation (RSD) of the volumes of the neighbors for each Voronoi cell in the tessellation. We propose a new observable, Σ¯ , which is the average RSD per unit area, calculated over the hypothesized boundary. We show that the location of the Σ¯ maximum correlates very well with the true values of the new particle masses. Our approach represents the natural extension of the one-dimensional kinematic endpoint method to the relevant three dimensions of invariant mass phase space.« less

Theoretical repeatability assessment without repetitive measurements in gradient high-performance liquid chromatography.

PubMed

Kotani, Akira; Tsutsumi, Risa; Shoji, Asaki; Hayashi, Yuzuru; Kusu, Fumiyo; Yamamoto, Kazuhiro; Hakamata, Hideki

2016-07-08

This paper puts forward a time and material-saving method for evaluating the repeatability of area measurements in gradient HPLC with UV detection (HPLC-UV), based on the function of mutual information (FUMI) theory which can theoretically provide the measurement standard deviation (SD) and detection limits through the stochastic properties of baseline noise with no recourse to repetitive measurements of real samples. The chromatographic determination of terbinafine hydrochloride and enalapril maleate is taken as an example. The best choice of the number of noise data points, inevitable for the theoretical evaluation, is shown to be 512 data points (10.24s at 50 point/s sampling rate of an A/D converter). Coupled with the relative SD (RSD) of sample injection variability in the instrument used, the theoretical evaluation is proved to give identical values of area measurement RSDs to those estimated by the usual repetitive method (n=6) over a wide concentration range of the analytes within the 95% confidence intervals of the latter RSD. The FUMI theory is not a statistical one, but the "statistical" reliability of its SD estimates (n=1) is observed to be as high as that attained by thirty-one measurements of the same samples (n=31). Copyright © 2016 Elsevier B.V. All rights reserved.

Detecting kinematic boundary surfaces in phase space: particle mass measurements in SUSY-like events

NASA Astrophysics Data System (ADS)

Debnath, Dipsikha; Gainer, James S.; Kilic, Can; Kim, Doojin; Matchev, Konstantin T.; Yang, Yuan-Pao

2017-06-01

We critically examine the classic endpoint method for particle mass determination, focusing on difficult corners of parameter space, where some of the measurements are not independent, while others are adversely affected by the experimental resolution. In such scenarios, mass differences can be measured relatively well, but the overall mass scale remains poorly constrained. Using the example of the standard SUSY decay chain \\tilde{q}\\to {\\tilde{χ}}_2^0\\to \\tilde{ℓ}\\to {\\tilde{χ}}_1^0 , we demonstrate that sensitivity to the remaining mass scale parameter can be recovered by measuring the two-dimensional kinematical boundary in the relevant three-dimensional phase space of invariant masses squared. We develop an algorithm for detecting this boundary, which uses the geometric properties of the Voronoi tessellation of the data, and in particular, the relative standard deviation (RSD) of the volumes of the neighbors for each Voronoi cell in the tessellation. We propose a new observable, \\overline{Σ} , which is the average RSD per unit area, calculated over the hypothesized boundary. We show that the location of the \\overline{Σ} maximum correlates very well with the true values of the new particle masses. Our approach represents the natural extension of the one-dimensional kinematic endpoint method to the relevant three dimensions of invariant mass phase space.

Application of retention modelling to the simulation of separation of organic anions in suppressed ion chromatography.

PubMed

Zakaria, Philip; Dicinoski, Greg W; Ng, Boon Khing; Shellie, Robert A; Hanna-Brown, Melissa; Haddad, Paul R

2009-09-18

The ion-exchange separation of organic anions of varying molecular mass has been demonstrated using ion chromatography with isocratic, gradient and multi-step eluent profiles on commercially available columns with UV detection. A retention model derived previously for inorganic ions and based solely on electrostatic interactions between the analytes and the stationary phase was applied. This model was found to accurately describe the observed elution of all the anions under isocratic, gradient and multi-step eluent conditions. Hydrophobic interactions, although likely to be present to varying degrees, did not limit the applicability of the ion-exchange retention model. Various instrumental configurations were investigated to overcome problems associated with the use of organic modifiers in the eluent which caused compatibility issues with the electrolytically derived, and subsequently suppressed, eluent. The preferred configuration allowed the organic modifier stream to bypass the eluent generator, followed by subsequent mixing before entering the injection valve and column. Accurate elution prediction was achieved even when using 5-step eluent profiles with errors in retention time generally being less than 1% relative standard deviation (RSD) and all being less than 5% RSD. Peak widths for linear gradient separations were also modelled and showed good agreement with experimentally determined values.

Graphene-metallic nanocomposites as modifiers in electrochemical glucose biosensor transducers

NASA Astrophysics Data System (ADS)

Altuntas, Derya Bal; Tepeli, Yudum; Anik, Ulku

2016-09-01

Graphene sheets and three different graphene-metallic nanocomposites including graphene-copper (graphene-Cu), graphene-nickel (graphene-Ni) and graphene-platinum (graphene-Pt) were prepared and characterized in the first place. Then the electrochemical performances of these nanocomposites were tested in glucose biosensor transducers, which were formed by combining these metallic nanocomposites with glucose oxidase enzyme and glassy carbon paste electrode (GCPE). This is the first work that includes the usage of these graphene-Me nanocomposites as a part of glucose biosensor transducer. Fabricated amperometric biosensors linear ranges were obtained as follow: For the plain graphene, the linear range was found in the concentration range between 50 μM and 800 μM with the RSD (n = 3 for 50 μM glucose) value of 12.86% and LOD value of 7.2 μM. For graphene-Pt modified glucose biosensor, the linear range was between 10 μM and 600 μM with the RSD (n = 3 for 50 μM glucose) value of 3.45% and LOD value of 3.06 μM. In the case of graphene-Ni modified glucose biosensor, the values were 25 μM to 600 μM with the RSD (n = 3 for 50 μM glucose) value of 8.76% and LOD value of 24.71 μM and for graphene-Cu modified glucose biosensor linear range was 25 μM to 400 μM with the RSD (n = 3 for 50 μM glucose) value of 3.93% and LOD value of 2.87 μM.

Predictors of Renal Denervation Efficacy in the Treatment of Resistant Hypertension.

PubMed

Ripp, Tatiana M; Mordovin, Victor F; Pekarskiy, Stanislav E; Ryabova, Tamara R; Zlobina, Marina V; Baev, Andrei E; Anfinogenova, Yana; Popov, Sergey V

2015-12-01

The aims of the study were to evaluate the effects of renal sympathetic denervation (RSD) on the heart and to identify the predictors of RSD efficacy in patients with resistant arterial hypertension. The study comprised 60 RSD patients (54.6 ± 9.5 years) who received full-dose antihypertensive therapy (4.1 drugs) including diuretics. Initially, 58.6% of patients had abnormal left ventricular (LV) diastolic function. All patients received echocardiography before and 24 weeks after RSD. Renal sympathetic denervation was achieved through the endovascular radiofrequency ablation (RFA) of the renal arteries. Drug therapy continued for the entire period of observation. After RSD, all patients were retrospectively assigned to two groups: group 1 comprised patients (n = 22; 36.7%) in whom the myocardial mass (MM) of the left ventricle decreased by more than 10 g after RSD; group 2 comprised patients (n = 38; 63.3%) in whom LV MM increased or decreased by less than 10 g. Anthropometry, arterial blood pressure, heart rate, therapy, and LV end-diastolic dimensions (EDD) were comparable in these groups. After RSD, the values of office blood pressure significantly decreased and MM regressed by more than 10 g in 36.7% of patients; LV diastolic function normalized in 31% of patients, and diastolic dysfunction improved in 14% of patients. The study found the associations between the initial LV wall dimensions and LV MM changes. Unlike LV EDD, arterial blood pressure, or heart rate, the initial values of LV wall thickness predicted LV MM regress. #NCT01499810 https://clinicaltrials.gov/ct2/show/NCT01499810.

Rapid determination of N,N-diethyl-m-toluamide and permethrin in human plasma by gas chromatography-mass spectrometry and pyridostigmine bromide by high-performance liquid chromatography.

PubMed

Cherstniakova, Svetlana A; Garcia, Gregory E; Strong, John; Bi, Daoqin; Weitz, Julie; Roy, Michael J; Cantilena, Louis R

2006-01-01

A rapid and highly sensitive gas chromatography-mass spectrometry (GC-MS) method for simultaneous determination of N,N-diethyl-m-toluamide (DEET) and permethrin with (2)H(10)-phenanthrene (98 atom %) as an internal standard and a separate external standard high-performance liquid chromatography (HPLC) method for pyridostigmine bromide (PB) determination in human plasma were developed and validated. The GC-MS method for DEET and permethrin quantification utilizes a one-step extraction with tert-butylmethylether. The HPLC method for PB quantification involves a solid-phase extraction and UV detection. The range of the analytical method for DEET and permethrin was 1 ng/mL to 100 ng/mL and for PB was 5 ng/mL to 100 ng/mL. Recovery from plasma proved to be more than 80%. The intraday precision ranged from 1.3% to 8% for DEET, from 2.1% to 11.4% for permethrin, and from 3.0% to 4.8% for PB. The interday precision was 3% for DEET, ranged from 5% to 9% for permethrin, and from 5% to 9% for PB. The accuracy for the limit of quantification was 92% +/- 8% relative standard deviation (RSD) for DEET, 112% +/- 11% RSD for permethrin, and 109% +/- 5% RSD for PB. All 3 compounds were stable in human plasma at -80 degrees C for at least 12 months and after 2 freeze-thaw cycles with RSD values ranging from 7.1% (DEET, 80 ng/mL) to 8.1% (DEET, 8 ng/mL), from 2.3% (permethrin, 80 ng/mL) to 11.6 % (permethrin, 8 ng/mL), and from 0.2% (PB, 80 ng/mL) to 3.6% (PB, 8 ng/mL). Both methods were successfully applied to pharmacokinetic/ pharmacodynamic studies of combined exposure of DEET (skin application), permethrin (treated uniforms), and PB (30 mg orally three times/day for four doses) in healthy volunteers (n = 81).

Neuropeptide Y as an indicator of successful alterations in sympathetic nervous activity after renal sympathetic denervation.

PubMed

Dörr, Oliver; Ewen, Sebastian; Liebetrau, Christoph; Möllmann, Helge; Gaede, Luise; Linz, Dominik; Hohl, Mathias; Troidl, Christian; Bauer, Timm; Böhm, Michael; Hamm, Christian; Mahfoud, Felix; Nef, Holger

2015-12-01

Renal sympathetic denervation (RSD) represents a safe and effective treatment option for certain patients with resistant hypertension and has been shown to decrease sympathetic activity. Neuropeptide Y (NPY) is a neurotransmitter that is co-released with norepinephrine and is up-regulated during increased sympathetic activity. The aim of the present study was to examine the effect of RSD on NPY and to analyze the association between changes in NPY levels and blood pressure reduction after RSD. A total of 150 consecutive patients (age 64.9 ± 10.2 years) from three clinical centers undergoing RSD were included in this study. Response to RSD was defined as an office systolic blood pressure (SBP) reduction of >10 mmHg 6 months after RSD. Venous blood samples for measurement of NPY were collected prior to and 6 months after RSD. BP and NPY levels were significantly reduced by 23/9 mmHg (p = 0.001/0.001) and 0.24 mg/dL (p < 0.01) 6 months after RSD. There was a significant correlation between baseline SBP- and RSD-related systolic BP reduction (r = -0.43; p < 0.001) and between serum NPY baseline values and NPY level changes (r = -0.52; p < 0.001) at the 6-month follow-up. The BP response to RSD (>10 mmHg) was associated with a significantly greater reduction in NPY level when compared with BP non-responders (p = 0.001). This study demonstrates an effect of RSD on serum NPY levels, a specific marker for sympathetic activity. The association between RSD-related changes in SBP and NPY levels provides further evidence of the effect of RSD on the sympathetic nervous system.

Development and evaluation of event-specific quantitative PCR method for genetically modified soybean A2704-12.

PubMed

Takabatake, Reona; Akiyama, Hiroshi; Sakata, Kozue; Onishi, Mari; Koiwa, Tomohiro; Futo, Satoshi; Minegishi, Yasutaka; Teshima, Reiko; Mano, Junichi; Furui, Satoshi; Kitta, Kazumi

2011-01-01

A novel real-time PCR-based analytical method was developed for the event-specific quantification of a genetically modified (GM) soybean event; A2704-12. During the plant transformation, DNA fragments derived from pUC19 plasmid were integrated in A2704-12, and the region was found to be A2704-12 specific. The pUC19-derived DNA sequences were used as primers for the specific detection of A2704-12. We first tried to construct a standard plasmid for A2704-12 quantification using pUC19. However, non-specific signals appeared with both qualitative and quantitative PCR analyses using the specific primers with pUC19 as a template, and we then constructed a plasmid using pBR322. The conversion factor (C(f)), which is required to calculate the amount of the genetically modified organism (GMO), was experimentally determined with two real-time PCR instruments, the Applied Biosystems 7900HT and the Applied Biosystems 7500. The determined C(f) values were both 0.98. The quantitative method was evaluated by means of blind tests in multi-laboratory trials using the two real-time PCR instruments. The limit of quantitation for the method was estimated to be 0.1%. The trueness and precision were evaluated as the bias and reproducibility of relative standard deviation (RSD(R)), and the determined bias and RSD(R) values for the method were each less than 20%. These results suggest that the developed method would be suitable for practical analyses for the detection and quantification of A2704-12.

Method for determination of aflatoxin M₁ in cheese and butter by HPLC using an immunoaffinity column.

PubMed

Sakuma, Hisako; Kamata, Yoichi; Sugita-Konishi, Yoshiko; Kawakami, Hiroshi

2011-01-01

A rapid, sensitive convenient method for determination of aflatoxin M₁ (AFM₁) in cheese and butter by HPLC was developed and validated. The method employs a safe extraction solution (mixture of acetonitrile, methanol and water) and an immunoaffinity column (IAC) for clean-up. Compared with the widely used method employing chloroform and a Florisil column, the IAC method has a short analytical time and there are no interference peaks. The limits of quantification (LOQ) of the IAC method were 0.12 and 0.14 µg/kg, while those of the Florisil column method were 0.47 and 0.23 µg/kg in cheese and buffer, respectively. The recovery and relative standard deviation (RSD) for cheese (spiked at 0.5 µg/kg) in the IAC method were 92% and 7%, respectively, while for the Florisil column method the corresponding values were 76% and 10%. The recovery and RSD for butter (spiked at 0.5 µg/kg) in the IAC method were 97% and 9%, and those in the Florisil method were 74% and 9%, respectively. In the IAC method, the values of in-house precision (n=2, day=5) of cheese and butter (spiked at 0.5 µg/kg) were 9% and 13%, respectively. The IAC method is superior to the Florisil column method in terms of safety, ease of handling, sensitivity and reliability. A survey of AFM₁ contamination in imported cheese and butter in Japan was conducted by the IAC method. AFM₁ was not detected in 60 samples of cheese and 30 samples of butter.

Determination of Trace lead (II) by Resonance Light Scattering Based on Pb (II)-KI-MG System

NASA Astrophysics Data System (ADS)

Chen, Ninghua; Yang, Yingchun; Hao, Shuai; Li, Yangmin

2018-01-01

In pH=3.0 weak acidic solution, it is found that Pb2+ can react with I-to form [PbI4]2-, and it further reacted with MG to form ion-association complex. As a result, the new spectra of RLS appeared and their intensities enhanced greatly. Accordingly, a new method developed for the determination of Pb (II).The appropriate reaction conditions were optimized through experiments. The results show that a strong and stable resonance scattering spectra emerge at the wavelength of 338 nm. The resonance light scattering strength (ΔIRLS) has good linear relationship with the concentration of Pb (II) in the range of 0.2 μg/mL ~ 1.0 μg/mL. The detection limits (LOD) is 0.0155 μg/mL. The relative standard deviation (RSD) is 3.61% (n=11) for the determination of 0.6 μg/mL Pb (II) standard solution. And this method was successfully applied to the determination of three environmental water samples (nongfu spring, tap water, laboratory wastewater). Results illustrate that the addition standard recovery are 80%~107% with relative standard deviation (RSD) between 1.8% to 4.6%.

Renal sympathetic denervation suppresses atrial fibrillation induced by acute atrial ischemia/infarction through inhibition of cardiac sympathetic activity.

PubMed

Zhou, Qina; Zhou, Xianhui; TuEr-Hong, ZuKe-la; Wang, Hongli; Yin, Tingting; Li, Yaodong; Zhang, Ling; Lu, Yanmei; Xing, Qiang; Zhang, Jianghua; Yang, Yining; Tang, Baopeng

2016-01-15

This study aims to explore the effects of renal sympathetic denervation (RSD) on atrial fibrillation (AF) inducibility and sympathetic activity induced by acute atrial ischemia/infarction. Acute ischemia/infarction was induced in 12 beagle dogs by ligating coronary arteries that supply the atria. Six dogs in the sham-RSD group did not undergo RSD, and six dogs without coronary artery ligation served as controls. AF induction rate, sympathetic discharge, catecholamine concentration and densities of tyrosine hydroxylase-positive nerves were measured. Acute atrial ischemia/infarction resulted in a significant increase of AF induction rate, which was decreased by RSD compared to controls (P<0.05). The root-mean-square peak value, peak area and number of sympathetic discharges were significantly augmented by atrial ischemia relative to the baseline and control (P<0.05). The number of sympathetic discharges was significantly reduced in the RSD group, compared to the control and sham-RSD groups (P<0.05). Norepinephrine and epinephrine concentrations in the atria, ventricle and kidney were elevated by atrial ischemia/infarction, but were reduced by RSD (P<0.05). Sympathetic hyperactivity was associated with pacing-induced AF after acute atrial ischemia/infarction. RSD has the potential to reduce the incidence of new-onset AF after acute atrial ischemia/infarction. The inhibition of cardiac sympathetic activity by RSD may be one of the major underlying mechanisms for the marked reduction of AF inducibility. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Determination of uranium in tap water by ICP-MS.

PubMed

El Himri, M; Pastor, A; de la Guardia, M

2000-05-01

A fast and accurate procedure has been developed for the determination of uranium at microg L(-1) level in tap and mineral water. The method is based on the direct introduction of samples, without any chemical pre-treatment, into an inductively coupled plasma mass spectrometer (ICP-MS). Uranium was determined at the mass number 238 using Rh as internal standard. The method provides a limit of detection of 2 ng L(-1) and a good repeatability with relative standard deviation values (RSD) about 3% for five independent analyses of samples containing 73 microg L(-1) of uranium. Recovery percentage values found for the determination of uranium in spiked natural samples varied between 91% and 106%. Results obtained are comparable with those found by radiochemical methods for natural samples and of the same order for the certified content of a reference material, thus indicating the accuracy of the ICP-MS procedure without the need of using isotope dilution. A series of mineral and tap waters from different parts of Spain and Morocco were analysed.

Verification of spectrophotometric method for nitrate analysis in water samples

NASA Astrophysics Data System (ADS)

Kurniawati, Puji; Gusrianti, Reny; Dwisiwi, Bledug Bernanti; Purbaningtias, Tri Esti; Wiyantoko, Bayu

2017-12-01

The aim of this research was to verify the spectrophotometric method to analyze nitrate in water samples using APHA 2012 Section 4500 NO3-B method. The verification parameters used were: linearity, method detection limit, level of quantitation, level of linearity, accuracy and precision. Linearity was obtained by using 0 to 50 mg/L nitrate standard solution and the correlation coefficient of standard calibration linear regression equation was 0.9981. The method detection limit (MDL) was defined as 0,1294 mg/L and limit of quantitation (LOQ) was 0,4117 mg/L. The result of a level of linearity (LOL) was 50 mg/L and nitrate concentration 10 to 50 mg/L was linear with a level of confidence was 99%. The accuracy was determined through recovery value was 109.1907%. The precision value was observed using % relative standard deviation (%RSD) from repeatability and its result was 1.0886%. The tested performance criteria showed that the methodology was verified under the laboratory conditions.

Determination of Aluminum in Dialysis Concentrates by Atomic Absorption Spectrometry after Coprecipitation with Lanthanum Phosphate.

PubMed

Selvi, Emine Kılıçkaya; Şahin, Uğur; Şahan, Serkan

2017-01-01

This method was developed for the determination of trace amounts of aluminum(III) in dialysis concentrates using atomic absorption spectrometry after coprecipitation with lanthanum phosphate. The analytical parameters that influenced the quantitative coprecipitation of analyte including amount of lanthanum, amount of phosfate, pH and duration time were optimized. The % recoveries of the analyte ion were in the range of 95-105 % with limit of detection (3s) of 0.5 µg l -1 . Preconcentration factor was found as 1000 and Relative Standard Deviation (RSD) % value obtained from model solutions was 2.5% for 0.02 mg L -1 . The accuracy of the method was evaluated with standard reference material (CWW-TMD Waste Water). The method was also applied to most concentrated acidic and basic dialysis concentrates with satisfactory results.

Determination of isoflavones in soy and selected foods containing soy by extraction, saponification, and liquid chromatography: collaborative study.

PubMed

Klump, S P; Allred, M C; MacDonald, J L; Ballam, J M

2001-01-01

Isoflavones are biologically active compounds occurring naturally in a variety of plants, with relatively high levels found in soybeans. Twelve laboratories participated in a collaborative study to determine the aglycon isoflavone content of 8 test samples of soy and foods containing soy. The analytical method for the determination of isoflavones incorporates a mild saponification step that reduces the number of analytes measured and permits quantitation versus commercially available, stable reference standards. Test samples were extracted at 65 degrees C with methanol-water (80 + 20), saponified with dilute sodium hydroxide solution, and analyzed by reversed-phase liquid chromatography with UV detection at 260 nm. Isoflavone results were reported as microg/aglycon/g or microg aglycon equivalents/g. The 8 test samples included 2 blind duplicates and 4 single test samples with total isoflavone concentrations ranging from approximately 50 to 3000 microg/g. Test samples of soy ingredients and products made with soy were distributed to collaborators with appropriate reference standards. Collaborators were asked to analyze test samples in duplicate on 2 separate days. The data were analyzed for individual isoflavone components, subtotals of daidzin-daidzein, glycitin-glycitein, and genistin-genistein, and total isoflavones. The relative standard deviation (RSD) for repeatability was 1.8-7.1%, and the RSD for reproducibility was 3.2-16.1% for total isoflavone values of 47-3099 microg/g.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bürger, Stefan; Riciputi, Lee R; Bostick, Debra A

A ThermoFisher 'Triton' multi-collector thermal ionization mass spectrometer (MC-TIMS) was evaluated for trace and ultra-trace level isotoperatioanalysis of actinides (uranium, plutonium, and americium), fission products and geolocators (strontium, cesium, and neodymium). Total efficiencies (atoms loaded to ions detected) of up to 0.5-2% for U, Pu, and Am, and 1-30% for Sr, Cs, and Nd can be reported employing resin bead load techniques onto flat ribbon Re filaments or resin beads loaded into a millimeter-sized cavity drilled into a Re rod. This results in detection limits of <0.1 fg (10{sup 4} atoms to 10{sup 5} atoms) for {sup 239-242+244}Pu, {sup 233+236}U,more » {sup 241-243}Am, {sup 89,90}Sr, and {sup 134,135,137}Cs, and {le} 1 pg for natural Nd isotopes (limited by the chemical processing blank) using a secondary electron multiplier (SEM) or multiple-ion counters (MICs). Relative standard deviations (RSD) as small as 0.1% and abundance sensitivities of 1 x 10{sup 6} or better using a SEM are reported here. Precisions of RSD {approx} 0.01-0.001% using a multi-collector Faraday cup array can be achieved at sub-nanogram concentrations for strontium and neodymium and are suitable to gain crucial geolocation information. The analytical protocols reported herein are of particular value for nuclear forensic and nuclear safeguard applications.« less

A spectrophotometric biochemical oxygen demand determination method using 2,6-dichlorophenolindophenol as the redox color indicator and the eukaryote Saccharomyces cerevisiae.

PubMed

Nakamura, Hideaki; Kobayashi, Shun; Hirata, Yu; Suzuki, Kyota; Mogi, Yotaro; Karube, Isao

2007-10-15

A method to determine the spectrophotometric biochemical oxygen demand (BOD(sp)) was studied with high sensitivity and reproducibility by employing 2,6-dichlorophenolindophenol (DCIP) as a redox color indicator, the yeast Saccharomyces cerevisiae, and a temperature-controlling system providing a three-consecutive-stir unit. The absorbance of DCIP decreased due to the metabolism of organic substances in aqueous samples by S. cerevisiae. Under optimum conditions, a calibration curve for glucose glutamic acid concentration between 1.1 and 22mg O(2) L(-1) (r=0.988, six points, n=3) was obtained when the incubation mixture was incubated for 10min at 30 degrees C. The reproducibility of the optical responses in the calibration curve was 1.77% (average of relative standard deviations; RSD(av)). Subsequently, the characterization of this method was studied. The optical responses to pure organic substances and the influence of chloride ions, artificial seawater, and heavy metal ions on the sensor response were investigated before use with real samples. Measurements of real samples using river water were performed and compared with those obtained using the BOD(5) method. Finally, stable responses were obtained for 36 days when the yeast cell suspension was stored at 4 degrees C (response reduction, 89%; RSD(av) value for 9 testing days, 8.4%).

Multiclass screening method based on solvent extraction and liquid chromatography-tandem mass spectrometry for the determination of antimicrobials and mycotoxins in egg.

PubMed

Capriotti, Anna Laura; Cavaliere, Chiara; Piovesana, Susy; Samperi, Roberto; Laganà, Aldo

2012-12-14

A QuEChERS (Quick Easy Cheap Effective Rugged Safe)-like extraction method was developed for the simultaneous analysis of veterinary drugs and mycotoxins in hen eggs by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray (ESI) source. Various classes of antimicrobials (tetracyclines, ionophores, coccidiostats, penicillins, cephalosporins, fluoroquinolones, sulfonamides) and mycotoxins (enniatins, beauvericin, ochratoxins, aflatoxins) were considered for the development of this method. Particular attention was devoted to extraction optimization: different solvents (acetone, acetonitrile and methanol), different pH values and different sample to extracting volume ratios were tested and evaluated in terms of recovery, relative standard deviation (RSD) and ESI signal suppression due to matrix effect. Chromatographic and mass spectrometric conditions were optimized to obtain the best instrumental performances for most of the analytes. Quantitative analysis was performed by means of matrix-matched calibration, in a range that varied depending on the analyte and its established maximum limit, when there was one. Recoveries at 100 μg kg(-1) spiking level were >62% (3

Determination of ammonium in a buddingtonite sample by ion-chromatography

USGS Publications Warehouse

Klock, P.R.; Lamothe, P.J.

1986-01-01

An ion-chromatographic method for the direct determination of ammonium, potassium, and sodium in geologic materials is described. Samples are decomposed with a mixture of hydrofluoric and hydrochloric acids in a sealed polycarbonate bottle heated in a microwave oven. The ion-chromatograph separates the cations and determines them by conductivity measurement. The ammonium concentrations thus determined have been verified by use of an ammonia-specific electrode. A total of 32 analyses of ammonium salts by both techniques showed an average error of -4%, with a relative standard deviation (RSD) of 6%. The ammonium concentrations found in a buddingtonite sample had an RSD of 2.2% and their mean agreed with that obtained by the Kjeldahl method. By use of the prescribed dilution of the sample, detection limits of 0.1% can be achieved for all three cations. ?? 1986.

A pretreatment method for HPLC analysis of cypermethrin in microbial degradation systems.

PubMed

Liu, Shuliang; Yao, Kai; Jia, Dongying; Zhao, Nan; Lai, Wen; Yuan, Huaiyu

2012-07-01

In this paper, a pretreatment method for high-performance liquid chromatography (HPLC) determination of cypermethrin (CY) in microbial degradation systems was systemically studied, primarily to solve the problem of inaccurate determination of CY concentration caused by its uneven distribution in the systems. A suitable pretreatment method was established, including sampling, extraction and dehydration of CY. Partial sampling could be taken for bacterial and yeast systems in which CY was uniformly dispersed by an emulsifying agent, while total sampling was only suitable for mold systems with or without an emulsifying agent. CY could be fully extracted from the samples in which microbial cells were disrupted by ultrasonic treatment with acetonitrile under ultrasonic condition. The extract could be effectively dehydrated and purified by passing it through an anhydrous Na(2)SO(4) column followed by an elution with acetonitrile. The determination of CY in the pretreated sample by HPLC showed a high precision [relative standard deviation (RSD) = 1.14%, n = 5] and a good stability over a period of five days (RSD = 1.57%, n = 5). The recoveries of CY in microbial degradation systems at three different spiked levels ranged from 95.68 to 108.09% (RSD = 0.50-5.87%, n = 5).

Highly sensitive, reproducible and stable SERS substrate based on reduced graphene oxide/silver nanoparticles coated weighing paper

NASA Astrophysics Data System (ADS)

Xiao, Guina; Li, Yunxiang; Shi, Wangzhou; Shen, Leo; Chen, Qi; Huang, Lei

2017-05-01

Paper-based surface-enhanced Raman scattering (SERS) substrates receive a great deal of attention due to low cost and high flexibility. Herein, we developed an efficient SERS substrate by gravure printing of sulfonated reduced graphene-oxide (S-RGO) thin film and inkjet printing of silver nanoparticles (AgNPs) on weighing paper successively. Malachite green (MG) and rhodamine 6G (R6G) were chosen as probe molecules to evaluate the enhanced performance of the fabricated SERS-active substrates. It was found that the S-RGO/AgNPs composite structure possessed higher enhancement ability than the pure AgNPs. The Raman enhancement factor of S-RGO/AgNPs was calculated to be as large as 109. The minimum detection limit for MG and R6G was down to 10-7 M with good linear responses (R2 = 0.9996, 0.9983) range from 10-4 M to 10-7 M. In addition, the S-RGO/AgNPs exhibited good uniformity with a relative standard deviation (RSD) of 7.90% measured by 572 points, excellent reproducibility with RSD smaller than 3.36%, and long-term stability with RSD less than 7.19%.

Major and minor oxide and trace element determination in silicate rocks by direct current plasma optical emission echelle spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bankston, D.C.; Humphris, S.E.; Thompson, G.

1979-07-01

A technique for the determination of major concentrations of SiO/sub 2/, Al/sub 2/O/sub 3/, Fe/sub 2/O/sub 3/, MgO, CaO, Na/sub 2/O, and K/sub 2/O, minor levels of TiO/sub 2/, P/sub 2/O/sub 5/, and MnO, and trace concentrations of Ba, Cr, Cu, Ni, Sr, V, and Zn, in semi-microsamples 200 mg) of powdered whole rock, is described. Chemically diverse standard reference rocks are used both for calibration and assessment of accuracy. A lithium metaborate fusion melt of each standard or sample is dissolved in dilute HNO/sub 3/ containing Cs/sup +/ at a level of 0.2% (w/v). The resulting solution is usedmore » to perform all analyses except those for Na/sub 2/O and K/sub 2/O, which are determined in a portion of the original sample solution wherein the Cs/sup +/ concentration has been raised to 0.32% (w/v). Analyses of both portions of each sample solution are performed using an optical emission spectrometer/spectrograph equipped with an echelle monochromator and a dc argon plasma excitation source. Trace element detection limits ranged from 2 ppM for Cu to 15 ppM for Zn. A study of precision based on replicate determinations in three splits of the proposed USGS reference basalt BHVO-1 yielded the following results: (1) For analyses of the major and minor oxide constituents, values of the percent relative standard deviation (RSD) ranged from 1 for CaO, to 21 for P/sub 2/O/sub 5/. 2) For trace element determinations, values of the RSD ranged from 2 for Cu, to 19 for Zn. 2 figures, 11 tables.« less

Comparative analysis of the main bioactive components of San-ao decoction and its series of formulations.

PubMed

Shu, Xiaoyun; Tang, Yuping; Jiang, Chenxue; Shang, Erxing; Fan, Xinshen; Ding, Anwei

2012-11-01

A high performance liquid chromatographic (HPLC) method with diode array detection (DAD) was established for simultaneous determination of seven main bioactive components in San-ao decoction and its series of formulae (San-ao decoction, Wu-ao decoction, Qi-ao decoction and Jia-wei San-ao decoction). Seven compounds were analyzed simultaneously with a XTerra C(18) column (4.6 mm × 250 mm, 5 µm) using a linear gradient elution of a mobile phase containing acetonitrile (A) and a buffer solution (0.02 mol/L potassium dihydrogen phosphate and adjusted to pH 3 using phosphoric acid) (B); the flow rate was 1.0 mL/min. The sample was detected with DAD at 210, 254 and 360 nm and the column was maintained at 30 °C. All the compounds showed good linearity (r2 > 0.9984) in the tested concentration range. The precisions were evaluated by intra-day and inter-day tests, and relative standard deviation (R.S.D.) values within the range of 0.83%–2.53% and 0.64%–2.77% were reported, respectively. The recoveries of the quantified compounds were observed to cover a range from 95.34% and 104.82% with R.S.D. values less than 2.72%. The validated method was successfully applied for the simultaneous determination of seven main bioactive components including ephedrine (1), amygdalin (2), liquiritin (3), benzoic acid (4), isoliquiritin (5), formononetin (6) and glycyrrhizic acid (7) in San-ao decoction and its series of formulae. The results also showed a wide variation in the content of the identified active compounds in these samples, which could also be helpful to illustrate the drug interactions after some herbs combined in different formulations.

Multi-objective optimization strategy based on desirability functions used for electrophoratic separation and quantification of rosiglitazone and glimepiride in plasma and formulations.

PubMed

Hefnawy, Mohamed M; Sultan, Maha A; Al-Johar, Haya I; Kassem, Mohamed G; Aboul-Enein, Hassan Y

2012-01-01

Multiple response simultaneous optimization employing Derringer's desirability function was used for the development of a capillary electrophoresis method for the simultaneous determination of rosiglitazone (RSG) and glimepiride (GLM) in plasma and formulations. Twenty experiments, taking the two resolutions, the analysis time, and the capillary current as the responses with three important factors--buffer morality, volte and column temperature--were used to design mathematical models. The experimental responses were fitted into a second order polynomial and the six responses were simultaneously optimized to predict the optimum conditions for the effective separation of the studied compounds. The separation was carried out by using capillary zone electrophoresis (CZE) with a silica capillary column and diode array detector at 210 nm. The optimum assay conditions were 52 mmol l⁻¹ phosphate buffer, pH 7, and voltage of 22 kV at 29 °C. The method showed good agreement between the experimental data and predictive value throughout the studied parameter space. The assay limit of detection was 0.02 µg ml⁻¹ and the effective working range at relative standard deviation (RSD) of ≤ 5% was 0.05-16 µg ml⁻¹ (r = 0.999) for both drugs. Analytical recoveries of the studied drugs from spiked plasma were 97.2-101.9 ± 0.31-3.0%. The precision of the assay was satisfactory; RSD was 1.07 and 1.14 for intra- and inter-assay precision, respectively. The proposed method has a great value in routine analysis of RSG and GLM for its therapeutic monitoring and pharmacokinetic studies. Copyright © 2011 John Wiley & Sons, Ltd.

Analysis of some chlorophenoxy acids and carbamate herbicides in water and soil as amide derivatives using gas chromatography-mass spectrometry.

PubMed

Salem, A A

2007-03-01

A newly developed method for determining three phenoxy acids and one carbamate herbicide in water and soil samples using gas chromatography with mass spectrometric detection is developed. Phenoxy acids are derivatized through a condensation reaction with a suitable aromatic amine. 1,1-Carbonyldiimidazole is used as a condensation reagent. Derivatization conditions are optimized with respect to the amount of analyte, amine, solvent, and derivatization reagent. The optimum derivatization yield is accomplished in acetonitrile. 4-Methoxy aniline is used as a derivatizing agent. Obtained derivatives are stable indefinitely. Enhancement in sensitivity is achieved by using the single-ion monitoring mass spectrometric mode. The effectiveness of the developed method is tested by determining investigated compounds in water and soil samples. Analytes are concentrated from water samples using liquid-phase extraction and solid-phase extraction. Soil samples are extracted using methanol. Detection limits of 1.00, 50.00, 100.00, and 1.00 ng/mL are obtained for 2-(1-methylethoxy)phenyl methylcarbamate (Baygon), 2-(3-chlorophenoxy)-propionic acid (Cloprop), 2,4,5-trichlorophenoxyacetic acid, and 4-(2,4-dichlorophenoxy)butyric acid, respectively. LPE for spiked water samples yields recoveries in the range of 60.6-95.7%, with relative standard deviation (RSD) values of 1.07-7.85% using single component calibration curves. Recoveries of 44.8-275.5%, with RSD values ranging from 1.43% to 8.61% were obtained using a mixed component calibration curves. SPE from water samples and soil samples showed low recoveries. The reason is attributed to the weak sorption capabilities of soil and Al(2)O(3).

Inter-laboratory validation of bioaccessibility testing for metals.

PubMed

Henderson, Rayetta G; Verougstraete, Violaine; Anderson, Kim; Arbildua, José J; Brock, Thomas O; Brouwers, Tony; Cappellini, Danielle; Delbeke, Katrien; Herting, Gunilla; Hixon, Greg; Odnevall Wallinder, Inger; Rodriguez, Patricio H; Van Assche, Frank; Wilrich, Peter; Oller, Adriana R

2014-10-01

Bioelution assays are fast, simple alternatives to in vivo testing. In this study, the intra- and inter-laboratory variability in bioaccessibility data generated by bioelution tests were evaluated in synthetic fluids relevant to oral, inhalation, and dermal exposure. Using one defined protocol, five laboratories measured metal release from cobalt oxide, cobalt powder, copper concentrate, Inconel alloy, leaded brass alloy, and nickel sulfate hexahydrate. Standard deviations of repeatability (sr) and reproducibility (sR) were used to evaluate the intra- and inter-laboratory variability, respectively. Examination of the sR:sr ratios demonstrated that, while gastric and lysosomal fluids had reasonably good reproducibility, other fluids did not show as good concordance between laboratories. Relative standard deviation (RSD) analysis showed more favorable reproducibility outcomes for some data sets; overall results varied more between- than within-laboratories. RSD analysis of sr showed good within-laboratory variability for all conditions except some metals in interstitial fluid. In general, these findings indicate that absolute bioaccessibility results in some biological fluids may vary between different laboratories. However, for most applications, measures of relative bioaccessibility are needed, diminishing the requirement for high inter-laboratory reproducibility in absolute metal releases. The inter-laboratory exercise suggests that the degrees of freedom within the protocol need to be addressed. Copyright © 2014 Elsevier Inc. All rights reserved.

Development of a Smartphone-based reading system for lateral flow immunoassay.

PubMed

Lee, Sangdae; Kim, Giyoung; Moon, Jihea

2014-11-01

This study was conducted to develop and evaluate the performance of the Smartphone-based reading system for the lateral flow immunoassay (LFIA). Smartphone-based reading system consists of a Samsung Galaxy S2 Smartphone, Smartphone application, and a LFIA reader. LFIA reader is composed of the close-up lens with a focal length up to 30 mm, white LED light, lithium polymer battery, and main body. The Smartphone application for image acquisition and data analysis was developed on the Android platform. The standard curve was obtained by plotting the measured P(T)/P(c) or A(T)/A(c) ratio versus Salmonella standard concentration. The mean, standard deviation (SD), recovery, and relative standard deviation (RSD) were also calculated using additional experimental results. These data were compared with that obtained from the benchtop LFIA reader. The LOD in both systems was observed with 10(6) CFU/mL. The results show high accuracy and good reproducibility with a RSD less than 10% in the range of 10(6) to 10(9) CFU/mL. Due to the simple structure, good sensitivity, and high accuracy of the Smartphone-based reading system, this system can be substituted for the benchtop LFIA reader for point-of-care medical diagnostics.

Influence of Renal Sympathetic Denervation on Cardiac Extracellular Matrix Turnover and Cardiac Fibrosis.

PubMed

Dörr, Oliver; Liebetrau, Christoph; Möllmann, Helge; Gaede, Luise; Troidl, Christian; Morczeck, Kareen; Wiebe, Jens; Hoffmann, Jedrzej; Voss, Sandra; Bauer, Timm; Hamm, Christian; Nef, Holger

2015-10-01

Renal sympathetic denervation (RSD) represents an effective treatment option for patients with resistant arterial hypertension (HT). Extracellular matrix (ECM) turnover and deposition are essential processes in HT-related cardiovascular remodeling, fibrosis, and cardiac hypertrophy and contribute to hypertensive heart disease. The primary aim of the present study was to examine the effect of RSD on increased collagen turnover as reflected by serum levels of amino-terminal pro-peptides (PINP, PIIINP) and a carboxyl-terminal pro-peptide (PICP), specific biomarkers for cardiac ECM turnover and cardiovascular fibrosis. A total of 100 consecutive patients (mean age: 65.9±10.1 years) undergoing RSD were included in this study. A therapeutic response was defined as an office systolic blood pressure (SBP) reduction of >10mm Hg 6 months after RSD. Venous serum samples for measurement of PICP, PINP, and PIIINP were collected prior to and 6 months after RSD. A significant reduction in the office SBP of 24.3 mm Hg (SBP baseline: 166.9±14.3 mm Hg (P < 0.001) was documented 6 months after RSD. At this time point, the serum levels of PICP, PINP, and PIIINP (P < 0.01) were significantly decreased compared to baseline values in patients with an increased collagen turnover, showing significant differences comparing BP responders and nonresponders. In addition to the effective blood pressure reduction in response to RSD, this study demonstrates a positive effect of RSD on biomarkers reflecting cardiovascular ECM turnover and deposition. These results suggest a beneficial effect of RSD on cardiovascular fibrosis, hypertensive heart disease, and end-organ damage in high-risk patients. © American Journal of Hypertension, Ltd 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Long-term verification of functional and structural renal damage after renal sympathetic denervation.

PubMed

Dörr, Oliver; Liebetrau, Christoph; Möllmann, Helge; Gaede, Luise; Troidl, Christian; Wiebe, Jens; Renker, Matthias; Bauer, Timm; Hamm, Christian; Nef, Holger

2016-06-01

Previous studies of renal sympathetic denervation (RSD) excluded patients with impaired renal function to avoid potential RSD-related renal damage. Measurement of the highly sensitive biomarkers neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) has shown that RSD does not aggravate renal damage during the early post-procedural period. The aim of the present study was to examine the effect of RSD on blood pressure (BP) reduction and renal function after a long-term follow-up. A total of 62 consecutive patients undergoing RSD were included in this study. Serum NGAL and KIM-1 were collected prior to RSD and at 24 hr, 48 hr, and 3 months after RSD. BP measurements, antihypertensive medication use, and safety events were followed over a three-year period. Follow-up data were available over 36.9[±3.4] months in 47 of 62 (75.8%) of the initially included patients. At this time point a significant systolic BP reduction of 23 mm Hg (P > 0.001) was documented, and there were no significant changes in serum creatinine (P = 0.14), blood urea nitrogen (P = 0.33), or estimated glomerular filtration rate (eGFR) (P = 0.2) values. There were also no significant changes documented in patients with impaired renal function (eGFR < 45 mL/min) during the early post- procedural period or the long-term follow-up (P = 0.34). The results of the present study show a sustained effect of RSD on BP reduction after a three-year follow-up, and there was no evidence of renal failure. These results provide verification of the long-term safety and effectiveness of RSD, even in patients with impaired renal function. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Automation of the anthrone assay for carbohydrate concentration determinations.

PubMed

Turula, Vincent E; Gore, Thomas; Singh, Suddham; Arumugham, Rasappa G

2010-03-01

Reported is the adaptation of a manual polysaccharide assay applicable for glycoconjugate vaccines such as Prevenar to an automated liquid handling system (LHS) for improved performance. The anthrone assay is used for carbohydrate concentration determinations and was scaled to the microtiter plate format with appropriate mixing, dispensing, and measuring operations. Adaptation and development of the LHS platform was performed with both dextran polysaccharides of various sizes and pneumococcal serotype 6A polysaccharide (PnPs 6A). A standard plate configuration was programmed such that the LHS diluted both calibration standards and a test sample multiple times with six replicate preparations per dilution. This extent of replication minimized the effect of any single deviation or delivery error that might have occurred. Analysis of the dextran polymers ranging in size from 214 kDa to 3.755 MDa showed that regardless of polymer chain length the hydrolysis was complete, as evident by uniform concentration measurements. No plate positional absorbance bias was observed; of 12 plates analyzed to examine positional bias the largest deviation observed was 0.02% percent relative standard deviation (%RSD). The high purity dextran also afforded the opportunity to assess LHS accuracy; nine replicate analyses of dextran yielded a mean accuracy of 101% recovery. As for precision, a total of 22 unique analyses were performed on a single lot of PnPs 6A, and the resulting variability was 2.5% RSD. This work demonstrated the capability of a LHS to perform the anthrone assay consistently and a reduced assay cycle time for greater laboratory capacity.

Single-side renal sympathetic denervation to treat malignant refractory hypertension in a solitary kidney patient.

PubMed

Ribichini, Flavio; Ferrara, Angela; Pighi, Michele; Pesarini, Gabriele; Gambaro, Alessia; Valvo, Enrico; Lupo, Antonio; Vassanelli, Corrado

2014-12-01

Renal sympathetic denervation (RSD) is emerging as a new therapeutic option for patients with severe hypertension refractory to medical therapy. Patients affected by renovascular or anatomical abnormalities have hitherto been systematically excluded from clinical trials with RSD because of concern about safety and the unknown efficacy of the procedure in this subgroup of patients. We describe the management of a case of RSD in a single-kidney patient with refractory hypertension; the patient had had a previous surgical right nephrectomy for renal cell carcinoma that subsequently required no other oncologic treatment. After multidisciplinary assessment, the patient underwent RSD. The procedure was performed through a 6F femoral access using the Symplicity™ RSD system (Medtronic, Mountain View, CA, USA). Radiofrequency was applied to the renal artery wall in 6 different points under general sedation with midazolam to control back pain caused by the procedure, that was performed without periprocedural complications. The patient was discharged 2 days later after a control of the vascular access site and routine biochemical examinations. The following 9-month follow up showed a significant reduction in blood pressure and stable renal function, without signs of renal damage. Our report confirms the feasibility of RSD in this delicate context, without evident negative effects on kidney function and with a significant reduction in blood pressure. Future studies are needed to fully clarify the value of RSD in single-kidney patients.

[Sampling in quality control of medicinal materials-A case of Epimedium].

PubMed

Wang, Chuanyi; Cao, Jinyi; Liang, Yun; Huang, Wenhua; Guo, Baolin

2009-04-01

To investigate the effect of the different individual number of sampling on the assay results of the medicinal materials. Epimedium pubescens and E. brevicornu were used as samples. The 6 sampling levels were formulated as 1 individual, 5, 10, 20, 30, 50 individuals mix, each level with 3 parallels and 1 individual level5 parallels. The contents of epimedin C and icariin, and the peak areas of epimedin A, epimedin B, rhamnosyl icarisid II and icarisid II in all samples were analyzed by HPLC. The variation degree varied with species and chemical constituents, but the RSD and the deviation from the true value decreased with the increase of individual number on the same chemical constituent. The sampling number should be more than 10 individuals in quality control of Epimedium, and 50 or more individuals would be better for representing the quality of medicinal materials.

Simultaneous determination of five marker constituents in Ssanghwa tang by HPLC/DAD

PubMed Central

Won, Jin Bae; Ma, Jin Yeul; Um, Young Ran; Ma, Choong Je

2010-01-01

A HPLC-DAD method was established for the simultaneous evaluation of five bioactive compounds in Ssanghwa tang (SHT) including glycyrrhizin, paeoniflorin, cinnamic acid, decursin and 6-gingerol. These compounds were separated in less than 40 min using a Dionex C18 column with a gradient elution system of water and methanol at a flow rate of 1 ml/min. Calibration curve of standard components presented excellent linear regression (R2 > 0.9903) within the test range. Limit of detection and limit of quantification varied from 0.07 to 0.46 μg/ml and 0.13 to 1.11 μg/ml, respectively. The relative standard deviations (RSDs) of data of the intraday and interday experiments were less than 3.67 and 5.73%, respectively. The accuracy of recovery test ranged from 95.98 to 105.88% with RSD values 0.10– 4.82%. PMID:20668576

Alternative Internal Standard Calibration of an Indirect Enzymatic Analytical Method for 2-MCPD Fatty Acid Esters.

PubMed

Koyama, Kazuo; Miyazaki, Kinuko; Abe, Kousuke; Egawa, Yoshitsugu; Fukazawa, Toru; Kitta, Tadashi; Miyashita, Takashi; Nezu, Toru; Nohara, Hidenori; Sano, Takashi; Takahashi, Yukinari; Taniguchi, Hideji; Yada, Hiroshi; Yamazaki, Kumiko; Watanabe, Yomi

2017-06-01

An indirect enzymatic analysis method for the quantification of fatty acid esters of 2-/3-monochloro-1,2-propanediol (2/3-MCPD) and glycidol was developed, using the deuterated internal standard of each free-form component. A statistical method for calibration and quantification of 2-MCPD-d 5 , which is difficult to obtain, is substituted by 3-MCPD-d 5 used for calculation of 3-MCPD. Using data from a previous collaborative study, the current method for the determination of 2-MCPD content using 2-MCPD-d 5 was compared to three alternative new methods using 3-MCPD-d 5 . The regression analysis showed that the alternative methods were unbiased compared to the current method. The relative standard deviation (RSD R ) among the testing laboratories was ≤ 15% and the Horwitz ratio was ≤ 1.0, a satisfactory value.

Determination of ammonium in river water and sewage samples by capillary zone electrophoresis with direct UV detection.

PubMed

Fukushi, Keiichi; Ito, Hideyuki; Kimura, Kenichi; Yokota, Kuriko; Saito, Keiitsu; Chayama, Kenji; Takeda, Sahori; Wakida, Shin-ichi

2006-02-17

We developed capillary zone electrophoresis (CZE) with direct UV detection for determination of ammonium in environmental water samples. Ammonium in the samples was partly converted into ammonia in the alkaline background electrolyte (BGE) during migration and was detected by molecular absorption of ammonia at 190 nm in approximately 7 min. The limit of detection (LOD) for ammonium was 0.24 mg/l (as nitrogen) at a signal-to-noise ratio of three. The respective values of the relative standard deviation (RSD) of peak area, peak height, and migration time for ammonium were 2.1, 1.8, and 0.46%. Major alkali and alkaline earth metal ions coexisting in the samples did not interfere with ammonium determination by the proposed method. The proposed method determined ammonium in surface water and sewage samples. The results were compared to those obtained using ion chromatography (IC).

Coupling solid-phase microextraction and high-performance liquid chromatography for direct and sensitive determination of halogenated fungicides in wine.

PubMed

Millán, S; Sampedro, M C; Unceta, N; Goicolea, M A; Rodríguez, E; Barrio, R J

2003-05-02

A solid-phase microextraction (SPME) method coupled to high-performance liquid chromatography with diode array detection (HPLC-DAD) for the analysis of six organochlorine fungicides (nuarimol, triadimenol, triadimefon, folpet, vinclozolin and penconazole) in wine was developed. For this purpose, polydimethylsiloxane-divinylbenzene-coated fibers were utilized and all factors affecting throughput, precision, and accuracy of the SPME method were investigated and optimized. These factors include: matrix influence, extraction and desorption time, percentage of ethanol, pH, salt effect and desorption mode. The performed analytical procedure showed detectability ranging from 4 to 27 microg l(-1) and precision from 2.4 to 14.2% (as intra-day relative standard deviation, RSD) and 4.7-25.7% (as inter-day RSD) depending on the fungicide. The results demonstrate the suitability of the SPME-HPLC-DAD method to analyze these organochlorine fungicides in red wine.

A multilayer membrane amperometric glucose sensor fabricated using planar techniques for large-scale production.

PubMed

Matsumoto, T; Saito, S; Ikeda, S

2006-03-23

This paper reports on a multilayer membrane amperometric glucose sensor fabricated using planar techniques. It is characterized by good reproducibility and suitable for large-scale production. The glucose sensor has 82 electrode sets formed on a single glass substrate, each with a platinum working electrode (WE), a platinum counter electrode (CE) and an Ag/AgCl reference electrode (RE). The electrode sets are coated with a membrane consisting of five layers: gamma-aminopropyltriethoxysilane (gamma-APTES), Nafion, glucose oxidase (GOX), gamma-APTES and perfluorocarbon polymer (PFCP), in that order. Tests have shown that the sensor has acceptably low dispersion (relative standard deviation, R.S.D.=42.9%, n=82), a wide measurement range (1.11-111 mM) and measurement stability over a 27-day period. Measurements of the glucose concentration in a control human urine sample demonstrated that the sensor has very low dispersion (R.S.D.=2.49%, n=10).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gundlach-Graham, Alexander W.; Dennis, Elise; Ray, Steven J.

An inductively coupled plasma distance-of-flight mass spectrometer (ICP-DOFMS) has been coupled with laser-ablation (LA) sample introduction for the elemental analysis of solids. ICP-DOFMS is well suited for the analysis of laser-generated aerosols because it offers both high-speed mass analysis and simultaneous multi-elemental detection. Here, we evaluate the analytical performance of the LA-ICP-DOFMS instrument, equipped with a microchannel plate-based imaging detector, for the measurement of steady-state LA signals, as well as transient signals produced from single LA events. Steady-state detection limits are 1 mg g1, and absolute single-pulse LA detection limits are 200 fg for uranium; the system is shown capablemore » of performing time-resolved single-pulse LA analysis. By leveraging the benefits of simultaneous multi-elemental detection, we also attain a good shot-to-shot reproducibility of 6% relative standard deviation (RSD) and isotope-ratio precision of 0.3% RSD with a 10 s integration time.« less

Spectrofluorimetric analysis of famotidine in pharmaceutical preparations and biological fluids by derivatization with benzoin

NASA Astrophysics Data System (ADS)

Alamgir, Malik; Khuhawar, Muhammad Yar; Memon, Saima Q.; Hayat, Amir; Zounr, Rizwan Ali

2015-01-01

A sensitive and simple spectrofluorimetric method has been developed for the analysis of famotidine, from pharmaceutical preparations and biological fluids after derivatization with benzoin. The reaction was carried out in alkaline medium with measurement of fluorescence intensity at 446 nm with excitation wavelength at 286 nm. Linear calibration was obtained with 0.5-15 μg/ml with coefficient of determination (r2) 0.997. The factors affecting the fluorescence intensity were optimized. The pharmaceutical additives and amino acid did not interfere in the determination. The mean percentage recovery (n = 4) calculated by standard addition from pharmaceutical preparation was 94.8-98.2% with relative standard deviation (RSD) 1.56-3.34% and recovery from deproteinized spiked serum and urine of healthy volunteers was 98.6-98.9% and 98.0-98.4% with RSD 0.34-0.84% and 0.29-0.87% respectively.

Determination of opiates and cocaine in urine by high pH mobile phase reversed phase UPLC-MS/MS.

PubMed

Berg, Thomas; Lundanes, Elsa; Christophersen, Asbjørg S; Strand, Dag Helge

2009-02-01

A fast and selective ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the determination of opiates (morphine, codeine, 6-monoacetylmorphine (6-MAM), pholcodine, oxycodone, ethylmorphine), cocaine and benzoylecgonine in urine has been developed and validated. Sample preparation was performed by solid phase extraction (SPE) on a mixed mode cation exchange (MCX) cartridge. For optimized chromatographic performance with repeatable retention times, narrow and symmetrical peaks, and focusing of all analytes at the column inlet at gradient start, a basic mobile phase consisting of 5mM ammonium bicarbonate, pH 10.2, and methanol (MeOH) was chosen. Positive electrospray ionization (ESI(+)) MS/MS detection was performed with a minimum of two multiple reaction monitoring (MRM) transitions for each analyte. Deuterium labelled-internal standards were used for six of the analytes. Between-assay retention time repeatabilities (n=10 series, 225 injections in total) had relative standard deviation (RSD) values within 0.1-0.6%. Limit of detection (LOD) and limit of quantification (LOQ) values were in the range 0.003-0.05 microM (0.001-0.02 microg/mL) and 0.01-0.16 microM (0.003-0.06 microg/mL), respectively. The RSD values of the between-assay repeatabilities of concentrations were

New concept for a toxicity assay based on multiple indexes from the wave shape of damped metabolic oscillation induced in living yeast cells (part I): characterization of the phenomenon.

PubMed

Nakamura, H; Suzuki, M

2007-10-01

The damped glycolytic oscillation phenomenon occurring in starved cells of the yeast Saccharomyces cerevisiae (NBRC 0565) was characterization for application to a toxicity bioassay. S. cerevisiae was grown under semi-anaerobic conditions. The transient oscillations were observed photometrically as the time course of the fluorescent intensity of reduced pyridine nucleotide resulting from instantaneous addition of glucose to a cell suspension. In this study, simple and reproducible conditions inducing damped oscillations were obtained by modifying a literature method. For estimation of the wave shapes of the damped oscillations we used six indexes. To investigate the total reproducibility as the averaged relative standard deviation (RSD(av)) for the six indexes obtained from the wave shapes, the damped oscillations were induced under the optimum conditions and the RSD(av) values were calculated as 14% in a buffer cell suspension (n = 62) and 22% in a water cell suspension (n = 78). Finally, the effects of glucose concentration on the six indexes were examined, and all the indexes changed when the glucose concentration was changed. Excellent correlations were obtained between the index of oscillation-state time and the concentration of glucose in a buffer cell suspension (r = 0.9985, 0.5-250 mmol L(-1), 10 points) and in a water cell suspension (r = 0.9989, 2.5 micromol L(-1)-250 mmol L(-1), 12 points), respectively.

Development and Validation of a Reversed Phase HPLC Method for Determination of Anacardic Acids in Cashew (Anacardium occidentale) Nut Shell Liquid.

PubMed

Oiram Filho, Francisco; Alcântra, Daniel Barbosa; Rodrigues, Tigressa Helena Soares; Alexandre E Silva, Lorena Mara; de Oliveira Silva, Ebenezer; Zocolo, Guilherme Julião; de Brito, Edy Sousa

2018-04-01

Cashew nut shell liquid (CNSL) contains phenolic lipids with aliphatic chains that are of commercial interest. In this work, a chromatographic method was developed to monitor and quantify anacardic acids (AnAc) in CNSL. Samples containing AnAc were analyzed on a high-performance liquid chromatograph coupled to a diode array detector, equipped with a reversed phase C18 (150 × 4.6 mm × 5 μm) column using acetonitrile and water as the mobile phase both acidified with acetic acid to pH 3.0 in an isocratic mode (80:20:1). The chromatographic method showed adequate selectivity, as it could clearly separate the different AnAc. To validate this method, AnAc triene was used as an external standard at seven different concentrations varying from 50 to 1,000 μg mL-1. The Student's t-test and F-test were applied to ensure high confidence for the obtained data from the analytical calibration curve. The results were satisfactory with respect to intra-day (relative standard deviation (RSD) = 0.60%) and inter-day (RSD = 0.67%) precision, linearity (y = 2,670.8x - 26,949, r2 > 0.9998), system suitability for retention time (RSD = 1.02%), area under the curve (RSD = 0.24%), selectivity and limits of detection (19.8 μg mg-1) and quantification (60.2 μg mg-1). The developed chromatographic method was applied for the analysis of different CNSL samples, and it was deemed suitable for the quantification of AnAc.

Quantitative determinations of levofloxacin and rifampicin in pharmaceutical and urine samples using nuclear magnetic resonance spectroscopy

NASA Astrophysics Data System (ADS)

Salem, A. A.; Mossa, H. A.; Barsoum, B. N.

2005-11-01

Rapid, specific and simple methods for determining levofloxacin and rifampicin antibiotic drugs in pharmaceutical and human urine samples were developed. The methods are based on 1H NMR spectroscopy using maleic acid as an internal standard and DMSO-d6 as NMR solvent. Integration of NMR signals at 8.9 and 8.2 ppm were, respectively, used for calculating the concentration of levofloxacin and rifampicin drugs per unit dose. Maleic acid signal at 6.2 ppm was used as the reference signal. Recoveries of (97.0-99.4) ± 0.5 and (98.3-99.7) ± 1.08% were obtained for pure levofloxacin and rifampicin, respectively. Corresponding recoveries of 98.5-100.3 and 96.8-100.0 were, respectively, obtained in pharmaceutical capsules and urine samples. Relative standard deviations (R.S.D.) values ≤2.7 were obtained for analyzed drugs in pure, pharmaceutical and urine samples. Statistical Student's t-test gave t-values ≤2.87 indicating insignificant difference between the real and the experimental values at the 95% confidence level. F-test revealed insignificant difference in precisions between the developed NMR methods and each of fluorimetric and HPLC methods for analyzing levofloxacin and rifampicin.

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the direct detection of 2-monochloropropanediol (2-MCPD) esters in edible oils.

PubMed

MacMahon, Shaun; Ridge, Clark D; Begley, Timothy H

2014-12-03

A new analytical method has been developed and validated for the detection and quantification of 2-monochloropropanediol (2-MCPD) esters in edible oils. The target compounds are potentially carcinogenic contaminants formed during the processing of edible oils. As the 2-MCPD esters that occur most frequently in refined edible oils were not commercially available, standards were synthesized with identity and purity (95+%) confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and (1)H NMR. Target analytes are separated from edible oil matrices using a two-step solid-phase extraction (SPE) procedure. The extracts are then analyzed using LC-MS/MS with electrospray ionization (ESI). The method has been validated for 11 2-MCPD diesters and 3 2-MCPD monoesters in soybean oil, olive oil, and palm oil using an external calibration curve. The ranges of average recoveries and relative standard deviations (RSD) across the three oil matrices at three spiking concentrations are 79-106% (3-13% RSD) for the 2-MCPD diesters and 72-108% (4-17% RSD) for the 2-MCPD monoesters, with limits of quantitation at or below 30 ng/g for the diesters and 90 ng/g for the monoesters.

Improved Gas Chromatographic Determination of Guanidino Compounds Using Isovaleroylacetone and Ethyl Chloroformate as Derivatizing Reagents.

PubMed

Zounr, Rizwan Ali; Khuhawar, Mumammad Yar; Jahangir, Taj Muhammad; Alamgir, Malik

2016-01-01

An improved GC method in terms of sensitivity and decrease in the analysis time has been developed for the analysis of eight guanidino compounds: guanidine (G), methylguanidine (MG), creatinine (CTN), guanidinoacetic acid (GAA), guanidinobutyric acid (GBA), guanidinopropionic acid (GPA), argenine (Arg), and guanidinosuccinic acid (GSA), using isovaleroylacetone (IVA) and ethyl chloroformate (ECF) as derivatizing reagents. The separation was obtained from column HP-5 (30 m × 0.32 mm i.d.) with film thickness of 0.25 μm within 11 min. The linear calibrations were obtained with 0.5 to 50 μg/mL with coefficient of determination (R(2)) within 0.9969 - 0.9998. Limits of detections (LODs) were within 5 - 140 ng/mL. The derivatization, separation and determination was repeatable (n = 6) with relative standard deviation (RSD) within 1.2 - 3.1%. The guanidino compounds were determined in deproteinized serum of healthy volunteers and uremic patients within below LOD to 8.8 μg/mL and below LOD to 43.99 μg/mL with RSD within 1.4 - 3.6%. The recovery of guanidino compounds calculated by standard addition from serum was within 96.1 - 98.9%, with RSD 1.4 - 3.6%.

Headspace gas chromatography with flame ionization detection (HS-GC-FID) for the determination of dissolved methane in wastewater.

PubMed

Beale, D J; Tjandraatmadja, G; Toifl, M; Goodman, N

2014-01-01

There is currently a need for a simple, accurate and reproducible method that quantifies the amount of dissolved methane in wastewater in order to realize the potential methane that can be recovered and account for any emissions. This paper presents such a method, using gas chromatography with flame ionization detection fitted with a GS-Gas PRO column coupled with a headspace auto sampler. A practical limit of detection for methane of 0.9 mg L(-1), with a retention time of 1.24 min, was obtained. It was found that the reproducibility and accuracy of the method increased significantly when samples were collected using an in-house constructed bailer sampling device and with the addition of 100 μL hydrochloric acid (HCl) and 25% sodium chloride (NaCl) and sonication for 30 min prior to analysis. Analysis of wastewater samples and wastewater sludge collected from a treatment facility were observed to range from 12.51 to 15.79 mg L(-1) (relative standard deviation (RSD) 8.1%) and 17.56 to 18.67 mg L(-1) (RSD 3.4%) respectively. The performance of this method was validated by repeatedly measuring a mid-level standard (n=8; 10 mg L(-1)), with an observed RSD of 4.6%.

Diffusion-weighted magnetic resonance imaging of parotid glands before and after abatacept therapy in patients with Sjögren's syndrome associated with rheumatoid arthritis: Utility to evaluate and predict response to treatment.

PubMed

Takahashi, Hiroyuki; Tsuboi, Hiroto; Yokosawa, Masahiro; Asashima, Hiromitsu; Hirota, Tomoya; Kondo, Yuya; Matsumoto, Isao; Sumida, Takayuki

2018-03-01

To compare parotid diffusion-weighted images (DWIs) taken before and after abatacept therapy in patients with Sjögren's syndrome (SS) associated with rheumatoid arthritis (RA) and to examine the utility in evaluation and prediction of response to therapy. DWIs of the parotid glands taken at baseline and 52 weeks after initiation of abatacept were analyzed in nine SS patients with RA using relative standard deviation (RSD) of the entire glands and signal intensity ratio (SIR) within the residual parenchyma. The correlation between changes in RSD and SIR and changes in salivary secretion based on Saxon's test was examined. Furthermore, baseline characteristics were compared in patients with increased and decreased salivary secretion after treatment. The predictive power of the parameter at baseline was examined using receiver operating characteristic (ROC) analysis. Abatacept improved salivary secretion from 2076 ± 1535 at baseline to 2857 ± 1431 mg/2 min at 52 weeks (n = 9, p = .05). Increase of salivary secretion was significantly higher in patients with decreased RSD (n = 6) than increased RSD (n = 3) (1241 ± 713, -137 ± 142 mg/2 min, p = .02). The increase and decrease in RSD completely accorded with those of salivary secretion. Furthermore, SIR was the only parameter that was significantly different between patients with posttreatment increase and decrease in salivary secretion (p = .04). ROC analysis showed the sensitivity and specificity of SIR at baseline of ≥13.0 × 10 -2 for the prediction of the response to abatacept were 75.0% and 83.3%, respectively. Parotid DWI seems to be useful for evaluating and predicting the response in salivary secretion to abatacept in SS patients with RA.

Determination of Flavonol Aglycones in Ginkgo biloba Dietary Supplement Crude Materials and Finished Products by High-Performance Liquid Chromatography: Single Laboratory Validation

PubMed Central

Gray, Dean; LeVanseler, Kerri; Pan, Meide

2008-01-01

A single laboratory validation (SLV) was completed for a method to determine the flavonol aglycones quercetin, kaempferol, and isorhamnetin in Ginkgo biloba products. The method calculates total glycosides based on these aglycones formed following acid hydrolysis. Nine matrixes were chosen for the study, including crude leaf material, standardized dry powder extract, single and multiple entity finished products, and ethanol and glycerol tinctures. For the 9 matrixes evaluated as part of this SLV, the method appeared to be selective and specific, with no observed interferences. The simplified 60 min oven heating hydrolysis procedure was effective for each of the matrixes studied, with no apparent or consistent differences between 60, 75, and 90 min at 90°C. A Youden ruggedness trial testing 7 factors with the potential to affect quantitative results showed that 2 factors (volume hydrolyzed and test sample extraction/hydrolysis weight) were the most important parameters for control during sample preparation. The method performed well in terms of precision, with 4 matrixes tested in triplicate over a 3-day period showing an overall repeatability (relative standard deviation, RSD) of 2.3%. Analysis of variance testing at α = 0.05 showed no significant differences among the within- or between-group sources of variation, although comparisons of within-day (Sw), between-day (Sb), and total (St) precision showed that a majority of the standard deviation came from within-day determinations for all matrixes. Accuracy testing at 2 levels (approximately 30 and 90% of the determined concentrations in standardized dry powder extract) from 2 complex negative control matrixes showed an overall 96% recovery and RSD of 1.0% for the high spike, and 94% recovery and RSD of 2.5% for the low spike. HorRat scores were within the limits for performance acceptability, ranging from 0.4 to 1.3. Based on the performance results presented herein, it is recommended that this method progress to the collaborative laboratory trial. PMID:16001841

Circular electrodes to reduce the current variation of OTFTs with the drop-casted semiconducting layer

NASA Astrophysics Data System (ADS)

Dipu Kabir, H. M.; Ahmed, Zubair; Kariyadan, Remashan; Zhang, Lining; Chan, Mansun

2018-06-01

Circular organic thin film transistor (OTFT) structures are proposed to reduce the impact of variable grain alignment on the drive current of the polycrystalline organic thin film transistor (OTFT). As the circular structure is planar symmetric, the orientation of the grain cannot affect the drive current of the circular OTFT. Thus, circular electrodes expected to provide a lower variation. Top-gate, bottom-contact circular and conventional OTFTs with drop-casted polycrystalline 6,13-Bis(triisopropyl-silylethynyl) (TIPS)-Pentacene organic semiconducting layer (OSC) are fabricated to verify the theoretical variation reduction. The relative standard deviation (RSD), defined as the ratio of standard deviation and the average of drive current is used as the degree of variations in different structures. According to our fabrication result, circular transistors have a significantly lower variation (20% RSD), compared to the variation of conventional OTFTs (61% RSD). His research interests include Organic Electronics, VLSI Design, Embedded System, Neural Networks, and Solid-state devices. Between July 2001 and December 2002, he was a Visiting Professor at University of California at Berkeley and the Co-director of the BSIM program. He is currently still consulting on the development of the next generation compact models. He has been actively contributing to the professional community and hold many positions. He was a Board of Governor, Chair of the Education Committee, the Chair of the Region 10 subcommittee and a Distinguished lecturer of the IEEE Electron Device Society. He has also chaired many international conferences and acting as editors for a number of technical journals. In addition, he has received many awards including the UC Regents Fellowship, Golden Keys Scholarship for Academic Excellence, SRC Inventor Recognition Award, Rockwell Research Fellowship, R&D 100 award (for the BSIM3v3 project), Distinguished Teaching Award, the Shenzhen Science and Technology Innovation awards, and EDS Education Award etc. He is a Fellow of HKIE, IET and IEEE.

DETERMINATION OF AZOXYSTROBIN AND DIFENOCONAZOLE IN PESTICIDE PRODUCTS.

PubMed

Lazić, S; Šunjka, D

2015-01-01

In this study a high performance liquid chromatographic (HPLC-DAD) procedure has been developed for the simultaneous determination of azoxystrobin and difenoconazole in suspension concentrate pesticide formulations, with the aim of the product quality control. Azoxystrobin, strobilurin fungicide and difenoconazole (cis,trans-3-chloro-4-[4-methyl-2-(1H-1,2,4-triazol-1-ylmethyl)-1,3-dioxolan-2-yl]phenyl 4-chlorophenyl ether), triazole fungicide, are used for the protection of plants from wide spectrum of fungal diseases. For the analysis LC system an Agilent Technologies 1100 Series was used. Good separation was achieved on a Zorbax SB-C18 column (5 μm, 250 mm x 3 mm internal diameter) using a mobile phase consisting of acetonitrile/ultrapure water (90:10, v/v), at a flow rate of 0.9 ml/minute and UV detection at 218 nm. Column temperature was 25 degrees C, injected volume was 1 μl. Retention times for azoxystrobin and difenoconazole were 2.504 min and 1.963 min, respectively. This method is validated according to the requirements for new methods, which include linearity, precision, accuracy and selectivity. The method demonstrates good linearity with r2 > 0.997. The repeatability of the method, expressed as relative standard deviation (RSD, %), was found to be 1.9% for azoxystrobin and 0.5% for difenoconazole. The precision of the method was also considered to be acceptable as the experimental repeatability relative standard deviation (RSD) was lower than the RSD calculated using the Horwitz equation of 1.7% and 1.4% for azoxystrobin and difenoconazole, respectively. The accuracy of the proposed method was determined from recovery experiments through standard addition procedure. The average recoveries of the three fortification levels were 101.9% for azoxystrobin and 103.2% for difenoconazole with RSDs of 1.1% and 1.2%. The method described in this paper is simple, precise, accurate and selective and represents a new and reliable way of simultaneous determination of azoxystrobin and difenoconazole in formulated products.

Effects of renal sympathetic denervation and angiotensin-converting enzyme inhibitor on left ventricular hypertrophy. Comparison in spontaneously hypertensive rats.

PubMed

Ding, X; Xu, X; Yan, Y; Song, X; Liu, S; Wang, G; Su, D; Jing, Q; Qin, Y

2015-06-01

The aim of this study was to investigate whether renal sympathetic denervation (RSD) is more effective on myocardial hypertrophy than the angiotensin-converting enzyme inhibitor (ACEI) perindopril in spontaneously hypertensive rats (SHRs). After bilateral renal denervation blood pressure (BP) was measured every 10 days. On day 50 the heart was (histo)pathologically examined. The ventricular weight to body weight ratios (VW/BW), myocardial diameter and collagen volume fraction (CVF) were calculated, and cardiac hypertrophy marker genes were analyzed by RT-PCR. At the baseline evaluation all groups had comparable BP. After treatment the BP of the RSD group was significantly reduced (p < 0.05). The BP of the RSD group was lower than that of the perindopril group on days 10, 20 and 30th (p < 0.05) but on day 50 systolic BP of the RSD group was significantly higher (p < 0.05) whereas there were no significant differences in diastolic BP. The VW/BW decreased in the RSD group, whereas the value did not change significantly in the perindopril group. The myocardial diameter of the left ventricular cardiomyocytes was also significantly lower in the RSD group and stayed the same in the perindopril group. Collagen volume fraction (CVF) in the RSD group was significantly lower than in the perindopril group (p < 0.05). Significant changes in the expression levels of NPPA, MYH7, and MYH6 (P < 0.05) were observed in the RD-SHR groups (p < 0.05). There was a significant difference in the expression level of MYH6 (p < 0.05) between the RSD group and the perindopril group but the expression levels of NPPA and MYH7 were not significantly different. In this study, RSD had a significant antihypertensive effect and inhibited hypertensive-induced cardiac hypertrophy in SHRs and showed advantages compared with ACEI in decreasing BP in the early stage and in inhibiting myocardial fibrosis.

Application of snapshot imaging spectrometer in environmental detection

NASA Astrophysics Data System (ADS)

Sun, Kai; Qin, Xiaolei; Zhang, Yu; Wang, Jinqiang

2017-10-01

This study aimed at the application of snapshot imaging spectrometer in environmental detection. The simulated sewage and dyeing wastewater were prepared and the optimal experimental conditions were determined. The white LED array was used as the detection light source and the image of the sample was collected by the imaging spectrometer developed in the laboratory to obtain the spectral information of the sample in the range of 400-800 nm. The standard curve between the absorbance and the concentration of the samples was established. The linear range of a single component of Rhoda mine B was 1-50 mg/L, the linear correlation coefficient was more than 0.99, the recovery was 93%-113% and the relative standard deviations (RSD) was 7.5%. The linear range of chemical oxygen demand (COD) standard solution was 50-900mg/L, the linear correlation coefficient was 0.981, the recovery was 91% -106% and the relative standard deviation (RSD) was 6.7%. The rapid, accurate and precise method for detecting dyes showed an excellent promise for on-site and emergency detection in environment. At the request of the proceedings editor, an updated version of this article was published on 17 October 2017. The original version of this article was replaced due to an accidental inversion of Figure 2 and Figure 3. The Figures have been corrected in the updated and republished version.

Quantitative Detection of Trace Malachite Green in Aquiculture Water Samples by Extractive Electrospray Ionization Mass Spectrometry

PubMed Central

Fang, Xiaowei; Yang, Shuiping; Chingin, Konstantin; Zhu, Liang; Zhang, Xinglei; Zhou, Zhiquan; Zhao, Zhanfeng

2016-01-01

Exposure to malachite green (MG) may pose great health risks to humans; thus, it is of prime importance to develop fast and robust methods to quantitatively screen the presence of malachite green in water. Herein the application of extractive electrospray ionization mass spectrometry (EESI-MS) has been extended to the trace detection of MG within lake water and aquiculture water, due to the intensive use of MG as a biocide in fisheries. This method has the advantage of obviating offline liquid-liquid extraction or tedious matrix separation prior to the measurement of malachite green in native aqueous medium. The experimental results indicate that the extrapolated detection limit for MG was ~3.8 μg·L−1 (S/N = 3) in lake water samples and ~0.5 μg·L−1 in ultrapure water under optimized experimental conditions. The signal intensity of MG showed good linearity over the concentration range of 10–1000 μg·L−1. Measurement of practical water samples fortified with MG at 0.01, 0.1 and 1.0 mg·L−1 gave a good validation of the established calibration curve. The average recoveries and relative standard deviation (RSD) of malachite green in lake water and Carassius carassius fish farm effluent water were 115% (6.64% RSD), 85.4% (9.17% RSD) and 96.0% (7.44% RSD), respectively. Overall, the established EESI-MS/MS method has been demonstrated suitable for sensitive and rapid (<2 min per sample) quantitative detection of malachite green in various aqueous media, indicating its potential for online real-time monitoring of real life samples. PMID:27529262

Quantitative Detection of Trace Malachite Green in Aquiculture Water Samples by Extractive Electrospray Ionization Mass Spectrometry.

PubMed

Fang, Xiaowei; Yang, Shuiping; Chingin, Konstantin; Zhu, Liang; Zhang, Xinglei; Zhou, Zhiquan; Zhao, Zhanfeng

2016-08-11

Exposure to malachite green (MG) may pose great health risks to humans; thus, it is of prime importance to develop fast and robust methods to quantitatively screen the presence of malachite green in water. Herein the application of extractive electrospray ionization mass spectrometry (EESI-MS) has been extended to the trace detection of MG within lake water and aquiculture water, due to the intensive use of MG as a biocide in fisheries. This method has the advantage of obviating offline liquid-liquid extraction or tedious matrix separation prior to the measurement of malachite green in native aqueous medium. The experimental results indicate that the extrapolated detection limit for MG was ~3.8 μg·L(-1) (S/N = 3) in lake water samples and ~0.5 μg·L(-1) in ultrapure water under optimized experimental conditions. The signal intensity of MG showed good linearity over the concentration range of 10-1000 μg·L(-1). Measurement of practical water samples fortified with MG at 0.01, 0.1 and 1.0 mg·L(-1) gave a good validation of the established calibration curve. The average recoveries and relative standard deviation (RSD) of malachite green in lake water and Carassius carassius fish farm effluent water were 115% (6.64% RSD), 85.4% (9.17% RSD) and 96.0% (7.44% RSD), respectively. Overall, the established EESI-MS/MS method has been demonstrated suitable for sensitive and rapid (<2 min per sample) quantitative detection of malachite green in various aqueous media, indicating its potential for online real-time monitoring of real life samples.

Rapid determination of fumonisins in corn-based products by liquid chromatography/tandem mass spectrometry.

PubMed

Li, Wei; Herrman, Timothy J; Dai, Susie Y

2010-01-01

A simple, fast, and robust method was developed for the determination of fumonisin B1 (FB1), fumonisin B2 (FB2), and fumonisin B3 (FB3) in corn-based human food and animal feed (cornmeal). The method involves a single extraction step followed by centrifugation and filtration before analysis by ultra-performance liquid chromatographylelectrospray ionization (UPLC/ESI)-MS/MS. The LC/MS/MS method developed here represents the fastest and simplest procedure (<30 min) among both conventional HPLC methods and other LC/MS methods using SPE cleanup. The potential for high throughput analysis makes the method particularly beneficial for regulatory agencies and analytical laboratories with a high sample volume. A single-laboratory validation was conducted by testing three different spiking levels (200, 500, and 1000 ng/g for FB1 and FB2; 100, 250, and 500 ng/g for FB3) for accuracy and precision. Recoveries of FB1 ranged from 93 to 98% with RSD values of 3-8%. Recoveries of FB2 ranged from 104 to 108%, with RSD values of 2-6%. Recoveries of FB3 ranged from 94 to 108%, with RSD values of 2-5%.

[Determination of emamectin benzoate residue in vegetables by high performance liquid chromatography with fluorescence detection].

PubMed

Zhang, Yan; Wu, Yinliang; Hu, Jiye; Wang, Hongwei; Pan, Canping; Liu, Fengmao

2008-01-01

A method was developed for the determination of emamectin benzoate residue in cabbage and mushroom using solid-phase extraction (SPE) and high performance liquid chromatography (HPLC) with fluorescence detection. The sample was extracted with ethyl acetate. Further cleanup was performed on a propylsulfonic acid solid phase extraction cartridge, followed by the derivatization with trifluoroacetic anhydride in the presence of N-methylimidazole. The amount of derivatized emamectin benzoate was determined by fluorescence detector after separation by HPLC. The detection limit was 0.10 microg/kg for cabbage and mushroom samples. The recoveries of emamectin benzoate in cabbage and mushroom samples were 78.6%-84.9%. The inter-day relative standard deviation (RSD) and intra-day RSD were 2.7%-6.0% and 3.1%-8.9%, respectively, at the fortified levels of 1.0-20.0 microg/kg. The calibration curve of emamectin benzoate in vegetables at the concentration range of 0.002 mg/L to 0.10 mg/L was linear (r = 0.9999).

Development of Silicalite/Glucose Oxidase-Based Biosensor and Its Application for Glucose Determination in Juices and Nectars

NASA Astrophysics Data System (ADS)

Dudchenko, Oleksandr Ye; Pyeshkova, Viktoriya M.; Soldatkin, Oleksandr O.; Akata, Burcu; Kasap, Berna O.; Soldatkin, Alexey P.; Dzyadevych, Sergei V.

2016-02-01

The application of silicalite for improvement of enzyme adsorption on new stainless steel electrodes is reported. Glucose oxidase (GOx) was immobilized by two methods: cross-linking by glutaraldehyde (GOx-GA) and cross-linking by glutaraldehyde along with GOx adsorption on silicalite-modified electrode (SME) (GOx-SME-GA). The GOx-SME-GA biosensors were characterized by a four- to fivefold higher sensitivity than GOx-GA biosensor. It was concluded that silicalite together with GA sufficiently enhances enzyme adhesion on stainless steel electrodes. The developed GOx-SME-GA biosensors were characterized by good reproducibility of biosensor preparation (relative standard deviation (RSD)—18 %), improved signal reproducibility (RSD of glucose determination was 7 %), and good storage stability (29 % loss of activity after 18-day storage). A series of fruit juices and nectars was analyzed using GOx-SME-GA biosensor for determination of glucose concentration. The obtained results showed good correlation with the data of high-performance liquid chromatography (HPLC) ( R = 0.99).

Spectrofluorimetric analysis of famotidine in pharmaceutical preparations and biological fluids by derivatization with benzoin.

PubMed

Alamgir, Malik; Khuhawar, Muhammad Yar; Memon, Saima Q; Hayat, Amir; Zounr, Rizwan Ali

2015-01-05

A sensitive and simple spectrofluorimetric method has been developed for the analysis of famotidine, from pharmaceutical preparations and biological fluids after derivatization with benzoin. The reaction was carried out in alkaline medium with measurement of fluorescence intensity at 446 nm with excitation wavelength at 286 nm. Linear calibration was obtained with 0.5-15 μg/ml with coefficient of determination (r(2)) 0.997. The factors affecting the fluorescence intensity were optimized. The pharmaceutical additives and amino acid did not interfere in the determination. The mean percentage recovery (n=4) calculated by standard addition from pharmaceutical preparation was 94.8-98.2% with relative standard deviation (RSD) 1.56-3.34% and recovery from deproteinized spiked serum and urine of healthy volunteers was 98.6-98.9% and 98.0-98.4% with RSD 0.34-0.84% and 0.29-0.87% respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

Simultaneous determination of mequindox, quinocetone, and their major metabolites in chicken and pork by UPLC-MS/MS.

PubMed

Li, Yanshen; Liu, Kaili; Beier, Ross C; Cao, Xingyuan; Shen, Jianzhong; Zhang, Suxia

2014-10-01

This report presents a UPLC-MS/MS method for determination of mequindox (MEQ), quinocetone (QCT) and their 11 metabolites in chicken and pork samples. Following extraction process with acetonitrile-ethyl acetate, acidulation, and re-extraction with ethyl acetate in turn, target analytes were further purified using C18 solid phase extraction (SPE) cartridges for UPLC-MS/MS analysis. Validation was processed with mean recoveries from 69.1% to 113.3% with intra-day relative standard deviation (RSD) <14.7%, inter-day RSD <19.2%, and limit of detection between 0.05 and 1.0 μg/kg for each analytes. The verified method was successfully applied to the quantitative determination of commercial samples. This developed procedure will help to control food animal products with MEQ and QCT residues, and facilitate further pharmacokinetic and residue studies of similar quinoxaline-1,4-dioxide veterinary drugs. Copyright © 2014 Elsevier Ltd. All rights reserved.

Development of Simultaneous Analysis of Thirteen Bioactive Compounds in So-Cheong-Ryong-Tang Using UPLC-DAD

PubMed Central

2018-01-01

So-Cheong-Ryong-Tang, which is a standardized Korean medicine of the National Health Insurance, is a traditional prescription for the treatment of allergic rhinitis, bronchitis, and bronchial asthma. Simultaneous analysis and development of SCRT is essential for its stability, efficacy, and risk management. In this study, a simple, reliable, and accurate method using ultrahigh-performance liquid chromatography (UPLC) fingerprinting with a diode array detector (DAD) was developed for the simultaneous analysis. The chromatographic separation of the analytes was performed by an ACQUITY UPLC BEH C18 column (1.7 μM, 2.1 × 100 mm, Waters) with a mobile phase of water containing 0.01% (v/v) phosphoric acid and acetonitrile containing 0.01% (v/v) phosphoric acid. The flow rate and detection wavelength were set at 0.4 mL/min and 215, 230, 254, and 280 nm. All calibration curves of the thirteen components showed good linearity (R2 > 0.999). The limit of detection and limit of quantification ranged 0.001–0.360 and 0.004–1.200 µg/mL, respectively. The relative standard deviation (RSD) of intra- and interday was less than 2.60%, and the recoveries were within the range 76.08–103.79% with an RSD value of 0.03–1.50%. The results showed that the developed method was simple, reliable, accurate, sensitive, and precise for the quantification of bioactive components of SCRT. PMID:29854559

Diagnosing and Correcting Mass Accuracy and Signal Intensity Error Due to Initial Ion Position Variations in a MALDI TOFMS

NASA Astrophysics Data System (ADS)

Malys, Brian J.; Piotrowski, Michelle L.; Owens, Kevin G.

2018-02-01

Frustrated by worse than expected error for both peak area and time-of-flight (TOF) in matrix assisted laser desorption ionization (MALDI) experiments using samples prepared by electrospray deposition, it was finally determined that there was a correlation between sample location on the target plate and the measured TOF/peak area. Variations in both TOF and peak area were found to be due to small differences in the initial position of ions formed in the source region of the TOF mass spectrometer. These differences arise largely from misalignment of the instrument sample stage, with a smaller contribution arising from the non-ideal shape of the target plates used. By physically measuring the target plates used and comparing TOF data collected from three different instruments, an estimate of the magnitude and direction of the sample stage misalignment was determined for each of the instruments. A correction method was developed to correct the TOFs and peak areas obtained for a given combination of target plate and instrument. Two correction factors are determined, one by initially collecting spectra from each sample position used and another by using spectra from a single position for each set of samples on a target plate. For TOF and mass values, use of the correction factor reduced the error by a factor of 4, with the relative standard deviation (RSD) of the corrected masses being reduced to 12-24 ppm. For the peak areas, the RSD was reduced from 28% to 16% for samples deposited twice onto two target plates over two days.

Diagnosing and Correcting Mass Accuracy and Signal Intensity Error Due to Initial Ion Position Variations in a MALDI TOFMS

NASA Astrophysics Data System (ADS)

Malys, Brian J.; Piotrowski, Michelle L.; Owens, Kevin G.

2017-12-01

Frustrated by worse than expected error for both peak area and time-of-flight (TOF) in matrix assisted laser desorption ionization (MALDI) experiments using samples prepared by electrospray deposition, it was finally determined that there was a correlation between sample location on the target plate and the measured TOF/peak area. Variations in both TOF and peak area were found to be due to small differences in the initial position of ions formed in the source region of the TOF mass spectrometer. These differences arise largely from misalignment of the instrument sample stage, with a smaller contribution arising from the non-ideal shape of the target plates used. By physically measuring the target plates used and comparing TOF data collected from three different instruments, an estimate of the magnitude and direction of the sample stage misalignment was determined for each of the instruments. A correction method was developed to correct the TOFs and peak areas obtained for a given combination of target plate and instrument. Two correction factors are determined, one by initially collecting spectra from each sample position used and another by using spectra from a single position for each set of samples on a target plate. For TOF and mass values, use of the correction factor reduced the error by a factor of 4, with the relative standard deviation (RSD) of the corrected masses being reduced to 12-24 ppm. For the peak areas, the RSD was reduced from 28% to 16% for samples deposited twice onto two target plates over two days. [Figure not available: see fulltext.

Automated multisyringe stir bar sorptive extraction using robust montmorillonite/epoxy-coated stir bars.

PubMed

Ghani, Milad; Saraji, Mohammad; Maya, Fernando; Cerdà, Víctor

2016-05-06

Herein we present a simple, rapid and low cost strategy for the preparation of robust stir bar coatings based on the combination of montmorillonite with epoxy resin. The composite stir bar was implemented in a novel automated multisyringe stir bar sorptive extraction system (MS-SBSE), and applied to the extraction of four chlorophenols (4-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol) as model compounds, followed by high performance liquid chromatography-diode array detection. The different experimental parameters of the MS-SBSE, such as sample volume, selection of the desorption solvent, desorption volume, desorption time, sample solution pH, salt effect and extraction time were studied. Under the optimum conditions, the detection limits were between 0.02 and 0.34μgL(-1). Relative standard deviations (RSD) of the method for the analytes at 10μgL(-1) concentration level ranged from 3.5% to 4.1% (as intra-day RSD) and from 3.9% to 4.3% (as inter-day RSD at 50μgL(-1) concentration level). Batch-to-batch reproducibility for three different stir bars was 4.6-5.1%. The enrichment factors were between 30 and 49. In order to investigate the capability of the developed technique for real sample analysis, well water, wastewater and leachates from a solid waste treatment plant were satisfactorily analyzed. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of cooking on enrofloxacin residues in chicken tissue.

PubMed

Lolo, M; Pedreira, S; Miranda, J M; Vázquez, B I; Franco, C M; Cepeda, A; Fente, C

2006-10-01

The aim of this study was to determine the effect of different cooking processes (microwaving, roasting, boiling, grilling and frying) on naturally incurred enrofloxacin residues in chicken muscle. Enrofloxacin and its metabolite, ciprofloxacin, were analysed using a validated LC-MS method with limits of detection (LOD) and quantification (LOQ), respectively, of 2 and 5 ng g-1 quinolones in muscle samples. The method was shown to be linear over the range 5-500 ng g-1. Mean intra-day relative standard deviation (RSD) at a concentration of 50 ng g-1 (n = 6) was 6%; inter-day RSD was 12%. A recovery study demonstrated that 65-101%, of the drug and metabolite could be recovered from the tissue. The RSD with naturally incurred roasted chicken breast was 9.18% at a concentration of 11 +/- 1.01 ng g-1 (n = 6). In water, enrofloxacin remained stable for 3 h when heated at 100 degrees C. It was concluded that residue data from raw tissue are valid for estimation of consumer exposure to this drug, as well as the ADI calculations because cooking procedures did not affect enrofloxacin residues, which remained stable during heating. However, there was an apparent decrease in quinolone concentration in tissue because some was lost by exudation into the liquid used for cooking. Conversely, for a cooking procedure with water loss, there was an apparent increase in residue concentration.

Molecular analysis of the Na+ channel blocking actions of the novel class I anti-arrhythmic agent RSD 921

PubMed Central

Pugsley, Michael K; Goldin, Alan L

1999-01-01

RSD 921 is a novel, structurally unique, class I Na+ channel blocking drug under development as a local anaesthetic agent and possibly for the treatment of cardiac arrhythmias. The effects of RSD 921 on wild-type heart, skeletal muscle, neuronal and non-inactivating IFMQ3 mutant neuronal Na+ channels expressed in Xenopus laevis oocytes were examined using a two-electrode voltage clamp.RSD 921 produced similarly potent tonic block of all three wild-type channel isoforms, with EC50 values between 35 and 47 μM, whereas the EC50 for block of the IFMQ3 mutant channel was 110±5.5 μM.Block of Na+ channels by RSD 921 was concentration and use-dependent, with marked frequency-dependent block of heart channels and mild frequency-dependent block of skeletal muscle, wild-type neuronal and IFMQ3 mutant channels.RSD 921 produced a minimal hyperpolarizing shift in the steady-state voltage-dependence of inactivation of all three wild-type channel isoforms.Open channel block of the IFMQ3 mutant channel was best fit with a first order blocking scheme with kon equal to 0.11±0.012×106 M−1 s−1 and koff equal to 12.5±2.5 s−1, resulting in KD of 117±31 μM. Recovery from open channel block occurred with a time constant of 14±2.7 s−1.These results suggest that RSD 921 preferentially interacts with the open state of the Na+ channel, and that the drug may produce potent local anaesthetic or anti-arrhythmic action under conditions of shortened action potentials, such as during anoxia or ischaemia. PMID:10369450

Molecular analysis of the Na+ channel blocking actions of the novel class I anti-arrhythmic agent RSD 921.

PubMed

Pugsley, M K; Goldin, A L

1999-05-01

RSD 921 is a novel, structurally unique, class I Na+ channel blocking drug under development as a local anaesthetic agent and possibly for the treatment of cardiac arrhythmias. The effects of RSD 921 on wild-type heart, skeletal muscle, neuronal and non-inactivating IFMQ3 mutant neuronal Na+ channels expressed in Xenopus laevis oocytes were examined using a two-electrode voltage clamp. RSD 921 produced similarly potent tonic block of all three wild-type channel isoforms, with EC50 values between 35 and 47 microM, whereas the EC50 for block of the IFMQ3 mutant channel was 110+5.5 microM. Block of Na+ channels by RSD 921 was concentration and use-dependent, with marked frequency-dependent block of heart channels and mild frequency-dependent block of skeletal muscle, wild-type neuronal and IFMQ3 mutant channels. RSD 921 produced a minimal hyperpolarizing shift in the steady-state voltage-dependence of inactivation of all three wild-type channel isoforms. Open channel block of the IFMQ3 mutant channel was best fit with a first order blocking scheme with k(on) equal to 0.11+/-0.012x10(6) M(-1) s(-1) and k(off) equal to 12.5+/-2.5 s(-1), resulting in KD of 117+/-31 microM. Recovery from open channel block occurred with a time constant of 14+/-2.7 s(-1). These results suggest that RSD 921 preferentially interacts with the open state of the Na+ channel, and that the drug may produce potent local anaesthetic or anti-arrhythmic action under conditions of shortened action potentials, such as during anoxia or ischaemia.

Renal denervation improves exercise blood pressure: insights from a randomized, sham-controlled trial.

PubMed

Fengler, Karl; Heinemann, Diana; Okon, Thomas; Röhnert, Karoline; Stiermaier, Thomas; von Röder, Maximilian; Besler, Christian; Müller, Ulrike; Höllriegel, Robert; Schuler, Gerhard; Desch, Steffen; Lurz, Philipp

2016-07-01

Despite the ongoing debate on the role of renal sympathetic denervation (RSD) in the management of therapy-resistant hypertension, little is known about its possible effects on exercise blood pressure (BP), a known predictor for future cardiovascular events. We sought to evaluate the effect of RSD on exercise BP in a randomized, sham-controlled trial in patients with mild hypertension. Patients with therapy-resistant mild hypertension (defined by mean daytime systolic BP between 135 and 149 mmHg or mean daytime diastolic BP between 90 and 94 mmHg on 24-h ambulatory BP measurement) were randomized to either radiofrequency-based RSD or a sham procedure. Patients underwent cardiopulmonary exercise testing at baseline and after 6 months. Of the 71 patients randomized, data from cardiopulmonary exercise testing were available for 48 patients (22 in the RSD group, 26 in the sham group). After 6 months, patients undergoing RSD had a significantly lower systolic BP at maximum exercise workload compared to baseline (-14.2 ± 26.1 mmHg, p = 0.009). In contrast, no change was observed in the sham group (0.6 ± 22.9 mmHg, p = 0.45, p = 0.04 for between-group comparison). When analyzing patients with exaggerated baseline exercise BP only, the effect was even more pronounced (RSD vs. sham -29.5 ± 23.4 vs. 0.1 ± 25.3 mmHg, p = 0.008). Exercise systolic BP values in patients with mild therapy-resistant hypertension are reduced after RSD as compared to a sham-procedure.

A simple LC method with UV detection for the analysis of creatine and creatinine and its application to several creatine formulations.

PubMed

Dash, Alekha K; Sawhney, Angeli

2002-07-31

The objective of this study was to develop a simple and sensitive LC method for the determination of creatine and creatinine in various creatine supplement formulations. The chromatographic system comprised of a LC-600 pump, SCL-6B system controller, and SPD-6AV detector (Shimadzu, Japan). The mobile phase consisted of 0.045 M ammonium sulfate in water. The chromatographic separation was achieved at ambient temperature on a Betabasic C-18 column (250 x 4.6 mm, Keystone Sci.). The flow rate was maintained at 0.75 ml/min and effluents are monitored at 205 nm. 4-(2-Aminoethyl)benzene sulfonamide was used as an internal standard (IS). This method required less than 7 min of chromatographic time. The standard curves were linear over the concentration range of 1-100 microg/ml for creatine and 2-100 microg/ml for creatinine, respectively. The relative standard deviations (RSD) for the within-day and day-to-day precision for creatine were within 1.0-4.6 and 2.2-4.7%, respectively. The RSD for the accuracy of creatine assay was in the range of 2.4-4.7%. The RSD values for the within-day precision, day-to-day precision and accuracy for creatinine validation were 1.7-4.4, 2.3-5.4 and 2.4-4.8%, respectively. This method was used to determine: (i) the creatine concentration in various marketed products; (ii) saturated solubility of various creatine salts; and (iii) stability of creatine in aqueous solution. In conclusion, a simple and sensitive LC method with UV detection was developed for the simultaneous determination of creatine and creatinine in formulations. Di-creatine citrate salt showed a higher aqueous solubility (at 25 degrees C) as compared to creatine and creatine monohydrate. Some of the over-the-counter (OTC) products tested contained a very low level of creatine in contrast to their label claim. Substantial conversion of creatine into creatinine was noticed in liquid formulation.

Study of vortex-assisted MSPD and LC-MS/MS using alternative solid supports for pharmaceutical extraction from marketed fish.

PubMed

Hertzog, Gabriel I; Soares, Karina L; Caldas, Sergiane S; Primel, Ednei G

2015-06-01

A procedure based on vortex-assisted matrix solid-phase dispersion (MSPD) for the extraction of 15 pharmaceuticals from fish samples with determination by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was validated. Florisil, C18, diatomaceous earth, chitin, and chitosan were evaluated as solid supports. Best results were obtained with 0.5 g of diatomaceous earth, 0.5 g of sodium sulfate, and 5 mL of methanol. Analytical recoveries ranged from 58 to 128 % with relative standard deviation (RSD) lower than 15 %. Limit of quantification (LOQ) values for the 15 compounds ranged from 5 to 1000 ng g(-1). The method under investigation has shown to be a simple and fast extraction tool with minimum instrumentation and low amount of reagent, resulting in method low cost. Besides, alternative materials, such as chitin and chitosan, which were applied to the dispersion step for the first time, were found to be interesting alternatives.

Determination of ibuprofen and flurbiprofen in pharmaceuticals by capillary zone electrophoresis.

PubMed

Hamoudová, Rafifa; Pospísilová, Marie

2006-06-16

Capillary zone electrophoresis with spectrophotometric detection was used for the determination of ibuprofen (IB) and flurbiprofen (FL) in pharmaceuticals. The separation was carried out in a fused silica capillary (60 cm x 100 microm i.d. effective length 45 cm) at 30 kV with UV detection at 232 nm. The optimized background electrolyte was 20mM N-(2-acetamido)-2-aminoethanesulfonic acid (ACES) with 20mM imidazole and 10mM alpha-cyclodextrin of pH 7.3. 2-Naphthoxyacetic acid was used as internal standard. A single analysis took less than 5 min. Rectilinear calibration ranges were 2-500 mg l(-1) for IB and 1-60 mg l(-1) for FL. The relative standard deviations (R.S.D.) values (n=6) were 1.53% for IB and 1.29% for FL (for 200 mg l(-1) IB and 10 mg l(-1) FL). This validated method has been successfully applied for the routine analysis of 10 commercially available pharmaceutical preparations (syrup, tablets, cream and gel).

Simultaneous Chloramphenicol and Florfenicol Determination by A Validated DLLME-HPLC-UV Method in Pasteurized Milk.

PubMed

Karami-Osboo, Rouhollah; Miri, Ramin; Javidnia, Katayoun; Kobarfard, Farzad

2016-01-01

The antibiotic residues in milk are a well-known serious problem and pose several health hazards to consumers. We have described a simple, rapid, and inexpensive DLLME-HPLC/UV technique for the extraction of chloramphenicol and florfenicol residues in milk samples. Under the optimum conditions, linearity of the method was observed over the range 0.02-0.85 µg/L with correlation coefficients > 0.999. The proposed method has been found to have a good limit of detection (signal to noise ratio = 3) for chloramphenicol (12.5 µg/Kg) and florfenicol (12.2 µg/Kg), and precision with relative standard deviation values under 15% (RSD, n = 3). Good recoveries (69.1-79.4%) were obtained for the extraction of the target analytes in milk samples. This simple and economic method has been applied for analyses of 15 real milk samples. Among all samples only one of them was contaminated to florfenicol; 62.4 µg/Kg and contamination to chloramphenicol was not detected.

Simultaneous Chloramphenicol and Florfenicol Determination by A Validated DLLME-HPLC-UV Method in Pasteurized Milk

PubMed Central

Karami-Osboo, Rouhollah; Miri, Ramin; Javidnia, Katayoun; Kobarfard, Farzad

2016-01-01

The antibiotic residues in milk are a well-known serious problem and pose several health hazards to consumers. We have described a simple, rapid, and inexpensive DLLME-HPLC/UV technique for the extraction of chloramphenicol and florfenicol residues in milk samples. Under the optimum conditions, linearity of the method was observed over the range 0.02-0.85 µg/L with correlation coefficients > 0.999. The proposed method has been found to have a good limit of detection (signal to noise ratio = 3) for chloramphenicol (12.5 µg/Kg) and florfenicol (12.2 µg/Kg), and precision with relative standard deviation values under 15% (RSD, n = 3). Good recoveries (69.1–79.4%) were obtained for the extraction of the target analytes in milk samples. This simple and economic method has been applied for analyses of 15 real milk samples. Among all samples only one of them was contaminated to florfenicol; 62.4 µg/Kg and contamination to chloramphenicol was not detected. PMID:27980571

Development and validation of a UV-spectrophotometric method for the determination of pheniramine maleate and its stability studies

NASA Astrophysics Data System (ADS)

Raghu, M. S.; Basavaiah, K.; Ramesh, P. J.; Abdulrahman, Sameer A. M.; Vinay, K. B.

2012-03-01

A sensitive, precise, and cost-effective UV-spectrophotometric method is described for the determination of pheniramine maleate (PAM) in bulk drug and tablets. The method is based on the measurement of absorbance of a PAM solution in 0.1 N HCl at 264 nm. As per the International Conference on Harmonization (ICH) guidelines, the method was validated for linearity, accuracy, precision, limits of detection (LOD) and quantification (LOQ), and robustness and ruggedness. A linear relationship between absorbance and concentration of PAM in the range of 2-40 μg/ml with a correlation coefficient (r) of 0.9998 was obtained. The LOD and LOQ values were found to be 0.18 and 0.39 μg/ml PAM, respectively. The precision of the method was satisfactory: the value of relative standard deviation (RSD) did not exceed 3.47%. The proposed method was applied successfully to the determination of PAM in tablets with good accuracy and precision. Percentages of the label claims ranged from 101.8 to 102.01% with the standard deviation (SD) from 0.64 to 0.72%. The accuracy of the method was further ascertained by recovery studies via a standard addition procedure. In addition, the forced degradation of PAM was conducted in accordance with the ICH guidelines. Acidic and basic hydrolysis, thermal stress, peroxide, and photolytic degradation were used to assess the stability-indicating power of the method. A substantial degradation was observed during oxidative and alkaline degradations. No degradation was observed under other stress conditions.

Validation of PCR methods for quantitation of genetically modified plants in food.

PubMed

Hübner, P; Waiblinger, H U; Pietsch, K; Brodmann, P

2001-01-01

For enforcement of the recently introduced labeling threshold for genetically modified organisms (GMOs) in food ingredients, quantitative detection methods such as quantitative competitive (QC-PCR) and real-time PCR are applied by official food control laboratories. The experiences of 3 European food control laboratories in validating such methods were compared to describe realistic performance characteristics of quantitative PCR detection methods. The limit of quantitation (LOQ) of GMO-specific, real-time PCR was experimentally determined to reach 30-50 target molecules, which is close to theoretical prediction. Starting PCR with 200 ng genomic plant DNA, the LOQ depends primarily on the genome size of the target plant and ranges from 0.02% for rice to 0.7% for wheat. The precision of quantitative PCR detection methods, expressed as relative standard deviation (RSD), varied from 10 to 30%. Using Bt176 corn containing test samples and applying Bt176 specific QC-PCR, mean values deviated from true values by -7to 18%, with an average of 2+/-10%. Ruggedness of real-time PCR detection methods was assessed in an interlaboratory study analyzing commercial, homogeneous food samples. Roundup Ready soybean DNA contents were determined in the range of 0.3 to 36%, relative to soybean DNA, with RSDs of about 25%. Taking the precision of quantitative PCR detection methods into account, suitable sample plans and sample sizes for GMO analysis are suggested. Because quantitative GMO detection methods measure GMO contents of samples in relation to reference material (calibrants), high priority must be given to international agreements and standardization on certified reference materials.

Validation of a method for the determination of zolpidem in human plasma using LC with fluorescence detection.

PubMed

Ring, P R; Bostick, J M

2000-04-01

A sensitive and selective high-performance liquid chromatography (HPLC) method was developed for the determination of zolpidem in human plasma. Zolpidem and the internal standard (trazodone) were extracted from human plasma that had been made basic. The basic sample was loaded onto a conditioned Bond Elut C18 cartridge, rinsed with water and eluted with methanol. Forty microliters were then injected onto the LC system. Separation was achieved on a C18 column (150 x 4.6 mm, 5 microm) with a mobile phase composed of acetonitrile:50 mM potassium phosphate monobasic at pH 6.0 (4:6, v/v). Detection was by fluorescence, with excitation at 254 nm and emission at 400 nm. The retention times of zolpidem and internal standard were approximately 4.7 and 5.3 min, respectively. The LC run time was 8 min. The assay was linear in concentration range 1-400 ng/ml for zolpidem in human plasma. The analysis of quality control samples for zolpidem (3, 30, and 300 ng/ml) demonstrated excellent precision with relative standard deviations (RSD) of 3.7, 4.6, and 3.0%, respectively (n = 18). The method was accurate with all intraday (n = 6) and overall (n = 18) mean concentrations within 5.8% from nominal at all quality control sample concentrations. This method was also performed using a Gilson Aspec XL automated sample processor and autoinjector. The samples were manually fortified with internal standard and made basic. The aspec then performed the solid phase extraction and made injections of the samples onto the LC system. Using the automated procedure for analysis, quality control samples for zolpidem (3, 30, and 300 ng/ml) demonstrated acceptable precision with RSD values of 9.0, 4.9, and 5.1%, respectively (n = 12). The method was accurate with all intracurve (n = 4) and overall (n = 12) mean values being less than 10.8% from nominal at all quality control sample concentrations.

A fast and simple solid phase microextraction coupled with gas chromatography-triple quadrupole mass spectrometry method for the assay of urinary markers of glutaric acidemias.

PubMed

Naccarato, Attilio; Gionfriddo, Emanuela; Elliani, Rosangela; Sindona, Giovanni; Tagarelli, Antonio

2014-10-30

The analysis of characteristic urinary acidic markers such as glutaric, 3-hydroxyglutaric, 2-hydroxyglutaric, adipic, suberic, sebacic, ethylmalonic, 3-hydroxyisovaleric and isobutyric acid constitutes the recommended follow-up testing procedure for glutaric acidemia type 1 (GA-1) and type 2 (GA-2). The goal of the work herein presented is the development of a fast and simple method for the quantification of these biomarkers in human urine. The proposed analytical approach is based on the use of solid phase microextraction (SPME) combined with gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS) afterward a rapid derivatization of acidic moieties by propyl chloroformate, propanol and pyridine. Trueness and precision of the proposed protocol, tested at 5, 30 and 80mgl -1 , provided satisfactory values: recoveries were in the range between 72% and 116% and the relative standard deviations (RSD%) were between 0.9% and 18% (except for isobutyric acid at 5mgl -1 ). The LOD values achieved by the proposed method ranged between 1.0 and 473μgl -1 . Copyright © 2014 Elsevier B.V. All rights reserved.

[Determination of total, soluble and insoluble dietary fiber in foods by enzymatic-gravimetric method].

PubMed

Yang, X; Yang, Y; Zhou, R; Bian, L

2001-11-01

For studying the contents of dietary fiber in general foods and functional foods, a enzymatic-gravimetric method recommended by AOAC was established in our laboratory. The method for the determination of total, soluble and insoluble dietary fiber in foods and functional foods could be used for many other kind of foods. The relative standard deviations (RSD) of reproducibility between-run and within-run were 2.04%-7.85%, 3.42%-55.23% respectively. The repeatability of the methods was good, and the methods are suitable for many foods.

A flow injection chemiluminescence system for the determination of isoniazid.

PubMed

Huang, Y; Zhang, Z; Zhang, D; Lv, J

2000-10-01

A chemiluminescence (CL) flow system is described for the determination of isoniazid based on its enhancement on the chemiluminescence (CL) emission produced upon mixing a hexacyanoferrate(III) solution with an alkaline luminol solution. The system responds linearly to isoniazid concentration in the range 0-1 mg/L with a detection limit (3sigma) of 0.03 microg/L, relative standard deviation (RSD) of 1.2% for 0.1 mg/L isoniazid (n = 11). The system has been successfully applied to the determination of isoniazid in pharmaceutical preparations.

Developing a computer-controlled simulated digestion system to predict the concentration of metabolizable energy of feedstuffs for rooster.

PubMed

Zhao, F; Ren, L Q; Mi, B M; Tan, H Z; Zhao, J T; Li, H; Zhang, H F; Zhang, Z Y

2014-04-01

Four experiments were conducted to evaluate the effectiveness of a computer-controlled simulated digestion system (CCSDS) for predicting apparent metabolizable energy (AME) and true metabolizable energy (TME) using in vitro digestible energy (IVDE) content of feeds for roosters. In Exp. 1, the repeatability of the IVDE assay was tested in corn, wheat, rapeseed meal, and cottonseed meal with 3 assays of each sample and each with 5 replicates of the same sample. In Exp. 2, the additivity of IVDE concentration in corn, soybean meal, and cottonseed meal was tested by comparing determined IVDE values of the complete diet with values predicted from measurements on individual ingredients. In Exp. 3, linear models to predict AME and TME based on IVDE were developed with 16 calibration samples. In Exp. 4, the accuracy of prediction models was tested by the differences between predicted and determined values for AME or TME of 6 ingredients and 4 diets. In Exp. 1, the mean CV of IVDE was 0.88% (range = 0.20 to 2.14%) for corn, wheat, rapeseed meal, and cottonseed meal. No difference in IVDE was observed between 3 assays of an ingredient, indicating that the IVDE assay is repeatable under these conditions. In Exp. 2, minimal differences (<21 kcal/kg) were observed between determined and calculated IVDE of 3 complete diets formulated with corn, soybean meal, and cottonseed meal, demonstrating that the IVDE values are additive in a complete diet. In Exp. 3, linear relationships between AME and IVDE and between TME and IVDE were observed in 16 calibration samples: AME = 1.062 × IVDE - 530 (R(2) = 0.97, residual standard deviation [RSD] = 146 kcal/kg, P < 0.001) and TME = 1.050 × IVDE - 16 (R(2) = 0.97, RSD = 148 kcal/kg, P < 0.001). Differences of less than 100 kcal/kg were observed between determined and predicted values in 10 and 9 of the 16 calibration samples for AME and TME, respectively. In Exp. 4, differences of less than 100 kcal/kg between determined and predicted values were observed in 3 and 4 of the 6 ingredient samples for AME and TME, respectively, and all 4 diets showed the differences of less than 25 kcal/kg between determined and predicted AME or TME. Our results indicate that the CCSDS is repeatable and additive. This system accurately predicted AME or TME on 17 of the 26 samples and may be a promising method to predict the energetic values of feed for poultry.

Analysis of processing contaminants in edible oils. Part 1. Liquid chromatography-tandem mass spectrometry method for the direct detection of 3-monochloropropanediol monoesters and glycidyl esters.

PubMed

MacMahon, Shaun; Mazzola, Eugene; Begley, Timothy H; Diachenko, Gregory W

2013-05-22

A new analytical method has been developed and validated for the detection of glycidyl esters (GEs) and 3-monochloropropanediol (3-MCPD) monoesters in edible oils. The target compounds represent two classes of potentially carcinogenic chemical contaminants formed during the processing of edible oils. Target analytes are separated from edible oil matrices using a two-step solid-phase extraction (SPE) procedure. The extracts are then analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI). Chromatographic conditions that separate sn-1 and sn-2 monoesters of 3-MCPD have been developed for the first time. The method has been validated for GEs, sn-1 3-MCPD monoesters of lauric, myristic, linolenic, linoleic, oleic, and stearic acids, and sn-2 3-MCPD monoesters of oleic and palmitic acids in coconut, olive, and palm oils using an external calibration curve. The range of average recoveries and relative standard deviations (RSDs) across the three oil matrices at three spiking concentrations are 84-115% (3-16% RSD) for the GEs, 95-113% (1-10% RSD) for the sn-1 3-MCPD monoesters, and 76.8-103% (5.1-11.2% RSD) for the sn-2 3-MCPD monoesters, with limits of quantitation at or below 30 ng/g for the GEs, 60 ng/g for sn-1 3-MCPD monoesters, and 180 ng/g for sn-2 3-MCPD monoesters.

Evaluating the precision of passive sampling methods using ...

EPA Pesticide Factsheets

To assess these models, four different thicknesses of low-density polyethylene (LDPE) passive samplers were co-deployed for 28 days in the water column at three sites in New Bedford Harbor, MA, USA. Each sampler was pre-loaded with six PCB performance reference compounds (PRCs) to assess equilibrium status, such that the percent of PRC lost would range depending on PRC and LDPE thickness. These data allow subsequent Cfree comparisons to be made in two ways: (1) comparing Cfree derived from one thickness using different models and (2) comparing Cfree derived from the same model using different thicknesses of LDPE. Following the deployments, the percent of PRC lost ranged from 0-100%. As expected, fractional equilibrium decreased with increasing PRC molecular weight as well as sampler thickness. Overall, a total of 27 PCBs (log KOW ranging from 5.07 – 8.09) were measured at Cfree concentrations varying from 0.05 pg/L (PCB 206) to about 200 ng/L (PCB 28) on a single LDPE sampler. Relative standard deviations (RSDs) for total PCB measurements using the same thickness and varying model types range from 0.04-12% and increased with sampler thickness. Total PCB RSD for measurements using the same model and varying thickness ranged from: 6 – 30%. No RSD trends between models were observed but RSD did increase as Cfree decreased. These findings indicate that existing models yield precise and reproducible results when using LDPE and PRCs to measure Cfree. This work in

Analysis of subcellular sized particles. Capillary electrophoresis with post-column laser-induced fluorescence detection versus flow cytometry.

PubMed

Poe, Bobby G; Navratil, Marian; Arriaga, Edgar A

2006-12-29

Flow cytometry (FCM) and more recently capillary electrophoresis with post-column laser-induced fluorescence detection (CE-LIF) have both been used for subcellular particle analysis but their analytical performance has not been compared. In this work, we compare a commercial FCM with an in-house built CE-LIF instrument using fluorescently labeled microspheres and isolated mitochondria. As evidenced by the relative standard deviation (RSD) of the individual fluorescence intensities, FCM is two-fold better than CE-LIF for microspheres with > or =1.5 x 10(6) molecules of equivalent soluble fluorescein (MESF). However, FCM has a comparatively low signal-to-noise ratio (S/N) and high RSD for microspheres with <1.5 x 10(6) MESF. CE-LIF, on the other hand, produces S/N ratios that are >25 times higher than FCM for all the microspheres tested and a lower RSD for microspheres with <1.5 x 10(6) MESF. When 10-N-nonyl acridine orange (NAO)-labeled mitochondria are analyzed, the S/N ratios of both techniques are similar. This appears to result from photobleaching of NAO-labeled mitochondria as they are detected by the LIF detector of the CE-LIF instrument. Both techniques have a niche in subcellular analysis; FCM has the advantage of collecting data for thousands of particles quickly, whereas CE-LIF consumes less than a nanoliter of sample and provides the electrophoretic mobility for individual particles.

Novel enzyme-linked immunosorbent assay for determination of fluvastatin in plasma at picogram level.

PubMed

Darwish, Ibrahim A; Al-Obaid, Abdul-Rahman M; Al-Malaq, Hamoud A

2009-11-15

For the first time, an enzyme-linked immunosorbent assay (ELISA) has been developed and validated for the determination of fluvastatin (FLV) in plasma samples at picogram level. The assay employed a polyclonal antibody that specifically recognizes FLV with high affinity, and FLV conjugate of bovine serum albumin (FLV-BSA) immobilized onto microplate wells as a solid-phase. The assay involved a competitive binding reaction between FLV, in plasma sample, and the immobilized FLV-BSA for the binding sites on a limited amount of the anti-FLV antibody. The bound anti-FLV antibody was quantified with horseradish peroxidase-labeled second anti-rabbit IgG antibody (HRP-IgG) and 3,3',5,5'-tetramethylbenzidine (TMB) as a substrate for the peroxidase enzyme. The concentration of FLV in the sample was quantified by its ability to inhibit the binding of the anti-FLV antibody to the immobilized FLV-BSA and subsequently the color intensity in the assay wells. The conditions for the proposed ELISA were investigated and the optimum conditions were employed in the determination of FLV in plasma samples. The assay limit of detection was 10 pg mL(-1) and the effective working range at relative standard deviations (RSD) of

Interlaboratory validation of quantitative duplex real-time PCR method for screening analysis of genetically modified maize.

PubMed

Takabatake, Reona; Koiwa, Tomohiro; Kasahara, Masaki; Takashima, Kaori; Futo, Satoshi; Minegishi, Yasutaka; Akiyama, Hiroshi; Teshima, Reiko; Oguchi, Taichi; Mano, Junichi; Furui, Satoshi; Kitta, Kazumi

2011-01-01

To reduce the cost and time required to routinely perform the genetically modified organism (GMO) test, we developed a duplex quantitative real-time PCR method for a screening analysis simultaneously targeting an event-specific segment for GA21 and Cauliflower Mosaic Virus 35S promoter (P35S) segment [Oguchi et al., J. Food Hyg. Soc. Japan, 50, 117-125 (2009)]. To confirm the validity of the method, an interlaboratory collaborative study was conducted. In the collaborative study, conversion factors (Cfs), which are required to calculate the GMO amount (%), were first determined for two real-time PCR instruments, the ABI PRISM 7900HT and the ABI PRISM 7500. A blind test was then conducted. The limit of quantitation for both GA21 and P35S was estimated to be 0.5% or less. The trueness and precision were evaluated as the bias and reproducibility of the relative standard deviation (RSD(R)). The determined bias and RSD(R) were each less than 25%. We believe the developed method would be useful for the practical screening analysis of GM maize.

Development of high-throughput and high sensitivity capillary gel electrophoresis platform method for Western, Eastern, and Venezuelan equine encephalitis (WEVEE) virus like particles (VLPs) purity determination and characterization.

PubMed

Gollapudi, Deepika; Wycuff, Diane L; Schwartz, Richard M; Cooper, Jonathan W; Cheng, K C

2017-10-01

In this paper, we describe development of a high-throughput, highly sensitive method based on Lab Chip CGE-SDS platform for purity determination and characterization of virus-like particle (VLP) vaccines. A capillary gel electrophoresis approach requiring about 41 s per sample for analysis and demonstrating sensitivity to protein initial concentrations as low as 20 μg/mL, this method has been used previously to evaluate monoclonal antibodies, but this application for lot release assay of VLPs using this platform is unique. The method was qualified and shown to be accurate for the quantitation of VLP purity. Assay repeatability was confirmed to be less than 2% relative standard deviation of the mean (% RSD) with interday precision less than 2% RSD. The assay can evaluate purified VLPs in a concentration range of 20-249 μg/mL for VEE and 20-250 μg/mL for EEE and WEE VLPs. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Permethylated-β-Cyclodextrin Capped CdTe Quantum Dot and its Sensitive Fluorescence Analysis of Malachite Green.

PubMed

Cao, Yujuan; Wei, Jiongling; Wu, Wei; Wang, Song; Hu, Xiaogang; Yu, Ying

2015-09-01

In the present work, the CdTe quantum dots were covalently conjugated with permethylated-β-cyclodextrin (OMe-β-CD) using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride as cross-linking reagent. The obtained functional quantum dots (OMe-β-CD/QDs) showed highly luminescent, water solubility and photostability as well as good inclusion ability to malachite green. A sensitive fluorescence method was developed for the analysis of malachite green in different samples. The good linearity was 2.0 × 10(-7)-1.0 × 10(-5) mol/L and the limit of detect was 1.7 × 10(-8) mol/L. The recoveries for three environmental water samples were 92.0-108.2 % with relative standard deviation (RSD) of 0.24-1.87 %, while the recovery for the fish sample was 94.3 % with RSD of 1.04 %. The results showed that the present method was sensitive and convenient to determine malachite green in complex samples. Graphical Abstract The analytical mechanism of OMe-β-CD/QDs and its linear response to MG.

Analysis of volatile thiols in alcoholic beverages by simultaneous derivatization/extraction and liquid chromatography-high resolution mass spectrometry.

PubMed

Vichi, Stefania; Cortés-Francisco, Nuria; Caixach, Josep

2015-05-15

A simultaneous derivatization/extraction method followed by liquid chromatography-electrospray-high resolution mass spectrometry for the determination of volatile thiols in hydroalcoholic matrixes was optimized and used to identify and quantify volatile thiols in wine and beer samples. The method was evaluated in terms of sensitivity, precision, accuracy and selectivity. The experimental LOQs of eleven thiols tested ranged between 0.01 ng/L and 10 ng/L. Intra-day relative standard deviation (RSD) was in general lower than 10% and inter-day RSD ranged between 10% and 30%. Recovery in the model and real matrixes ranged from 45% to 129%. The method was then applied for the analysis of four white wines and six beers. Five out of the eleven reference thiols were identified and quantified in the samples analyzed. The non-target approach, carried out by monitoring the diagnostic ion at m/z 275.9922 [C13H10ONSe](+) in the fragmentation spectrum, allowed detecting, in the same samples, fourteen non-target thiols. Copyright © 2014 Elsevier Ltd. All rights reserved.

Spark ablation-inductively coupled plasma spectrometry for analysis of geologic materials

USGS Publications Warehouse

Golightly, D.W.; Montaser, A.; Smith, B.L.; Dorrzapf, A.F.

1989-01-01

Spark ablation-inductively coupled plasma (SA-ICP) spectrometry is applied to the measurement of hafnium-zirconium ratios in zircons and to the determination of cerium, cobalt, iron, lead, nickel and phosphorus in ferromanganese nodules. Six operating parameters used for the high-voltage spark and argon-ICP combination are established by sequential simplex optimization of both signal-to-background ratio and signal-to-noise ratio. The time-dependences of the atomic emission signals of analytes and matrix elements ablated from a finely pulverized sample embedded in a pressed disk of copper demonstrate selective sampling by the spark. Concentration ratios of hafnium to zirconium in zircons are measured with a precision of 4% (relative standard deviation, RSD). For ferromanganese nodules, spectral measurements based on intensity ratios of analyte line to the Mn(II) 257.610 nm line provide precisions of analysis in the range from 7 to 14% RSD. The accuracy of analysis depends on use of standard additions of the reference material USGS Nod P-1, and an independent measurement of the Mn concentration. ?? 1989.

Investigation of six bioactive anthraquinones in slimming tea by accelerated solvent extraction and high performance capillary electrophoresis with diode-array detection.

PubMed

Wang, Ning; Su, Ming; Liang, Shuxuan; Sun, Hanwen

2016-05-15

A rapid and effective method for effective separation and rapid simultaneous determination of six bioactive anthraquinones by capillary zone electrophoresis was developed. An accelerated solvent extraction procedure was used for the extraction of anthraquinones from slimming tea. Under the optimized conditions, the effective separation of six anthraquinones was achieved within 8 min. Good linearity was achieved, with a correlation coefficient (r) of ⩾ 0.999. The limit of detection ranged from 0.33 to 1.40 μg mL(-1). The intra- and inter-day relative standard deviation (RSD) of the six analytes was in the range of 2.3-3.9% and 3.2-4.9%, respectively. The average recovery of the six analytes from real tea samples was in the range of 86.15-98.30% with the RSD of 1.04-4.99%. The developed and validated method has speediness, high sensitivity, recovery and precision, and can be applied for the quality control of slimming tea. Copyright © 2015 Elsevier Ltd. All rights reserved.

Atmospheric pressure gas chromatography quadrupole-time-of-flight mass spectrometry for simultaneous determination of fifteen organochlorine pesticides in soil and water.

PubMed

Cheng, Zhipeng; Dong, Fengshou; Xu, Jun; Liu, Xingang; Wu, Xiaohu; Chen, Zenglong; Pan, Xinglu; Zheng, Yongquan

2016-02-26

In this study, the application of atmospheric pressure gas chromatography quadrupole-time-of-flight mass spectrometry (APGC-QTOF-MS) has been investigated for simultaneous determination of fifteen organochlorine pesticides in soil and water. Soft ionization of atmospheric pressure gas chromatography was evaluated by comparing with traditional more energetic electron impact ionization (EI). APGC-QTOF-MS showed a sensitivity enhancement by approximately 7-305 times. The QuEChERs (Quick, Easy, Cheap, Effective, Rugged, and Safe) method was used to pretreat the soil samples and solid phase extraction (SPE) cleanup was used for water samples. Precision, accuracy and stability experiments were undertaken to evaluate the feasibility of the method. The results showed that the mean recoveries for all the pesticides from the soil samples were 70.3-118.9% with 0.4-18.3% intra-day relative standard deviations (RSD) and 1.0-15.6% inter-day RSD at 10, 50 and 500 μg/L levels, while the mean recoveries of water samples were 70.0-118.0% with 1.1-17.8% intra-day RSD and 0.5-12.2% inter-day RSD at 0.1, 0.5 and 1.0 μg/L levels. Excellent linearity (0.9931 ≦ r(2)≤ 0.9999) was obtained for each pesticides in the soil and water matrix calibration curves within the range of 0.01-1.0mg/L. The limits of detection (LOD) for each of the 15 pesticides was less than 3.00 μg/L, while the limit of quantification (LOQ) was less than 9.99 μg/L in soil and water. Furthermore, the developed method was successfully applied to monitor the targeted pesticides in real soil and water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Improved in silico prediction of carcinogenic potency (TD50) and the risk specific dose (RSD) adjusted Threshold of Toxicological Concern (TTC) for genotoxic chemicals and pharmaceutical impurities.

PubMed

Contrera, Joseph F

2011-02-01

The Threshold of Toxicological Concern (TTC) is a level of exposure to a genotoxic impurity that is considered to represent a negligible risk to humans. The TTC was derived from the results of rodent carcinogenicity TD50 values that are a measure of carcinogenic potency. The TTC currently sets a default limit of 1.5 μg/day in food contact substances and pharmaceuticals for all genotoxic impurities without carcinogenicity data. Bercu et al. (2010) used the QSAR predicted TD50 to calculate a risk specific dose (RSD) which is a carcinogenic potency adjusted TTC for genotoxic impurities. This promising approach is currently limited by the software used, a combination of MC4PC (www.multicase.com) and a Lilly Inc. in-house software (VISDOM) that is not available to the public. In this report the TD50 and RSD were predicted using a commercially available software, SciQSAR (formally MDL-QSAR, www.scimatics.com) employing the same TD50 training data set and external validation test set that was used by Bercu et al. (2010). The results demonstrate the general applicability of QSAR predicted TD50 values to determine the RSDs for genotoxic impurities and the improved performance of SciQSAR for predicting TD50 values. Copyright © 2010 Elsevier Inc. All rights reserved.

Determination of urinary levels of leukotriene B(4) using ad highly specific and sensitive methodology based on automatic MEPS combined with UHPLC-PDA analysis.

PubMed

Perestrelo, Rosa; Silva, Catarina L; Câmara, José S

2015-11-01

Leukotriene B4 (LTB4) is a potent mediator of inflammation and plays a key function in the pathophysiology of chronic asthma. Detectable urinary levels of LTB4, arises from the activation of leukotriene pathways. In this study an ultra-fast, selective and sensitive analytical method based on semi-automatic microextraction by packed sorbents (MEPS) technique, using a new digitally controlled syringe (eVol®) combined with ultra-high pressure liquid chromatography (UHPLC), is proposed for the measurement of urinary LTB4 (U-LTB4) levels in a group of asthmatic patients (APs) and healthy controls (CTRL). Important parameters affecting MEPS performance, namely sorbent type, number of extraction cycles (extract-discard) and elution volume, were evaluated. The optimal experimental conditions among those investigated for the quantification of U-LTB4 in urine samples were as follows: porous graphitic carbon sorbent (PGC), 10 extractions cycle (10×250 μL of sample) and LTB4 elution with 100 μL of acetonitrile. The UHPLC optimum conditions resulted in a mobile phase consisting of 95% (v/v) of acid aqueous solution (v/v), and acetonitrile 5% (v/v); flow rate of 500 µL/min, and a column temperature of 37±0.1 °C. Under optimized conditions the proposed method exhibit good selectivity and sensitivity LOD (0.37 ng/mL) and LOQ (1.22 ng/mL). The recovery ranging from 86.4 to 101.1% for LTB4, with relative standard deviations (% RSD) no larger than 5%. In addition, the method also afforded good results in terms of linearity (r(2)>0.995) within the established concentration range, with a residual deviation for each calibration point below 6%, and intra- and inter-day repeatability in urine samples with RSD values lower than 4 and 5%, respectively. The application of the method to urine samples revealed a tendency towards the increased urinary LTB4 levels in APs (5.42±0.17 ng/mL) when compared to those of CTRL group (from ND to 1.9 ng/mL). Urinary measurement of LTB4 may be an interesting and non-invasive option to assess control of asthma. Copyright © 2015 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Secchieri, M.; Benassi, C.A.; Pastore, S.

A method for the quail-quantitative evaluation of pentachlorophenol (PCP) in solid matrixes has been developed. The procedure is based on solid-liquid extraction of solid samples (leather or wood), followed by purification on a cyanopropyl column and determination of the preservative by second derivative UV spectroscopy considering the PCP A peak-through value (304-297 nm). The method allows rapid PCP determination in the concentration range 1-40 micrograms/mL; any matrix interference is avoided by the purification step and recoveries of the preservative were 99.12% (RSD% 0.13) for the leather matrix and 98.03 (RSD% 0.17) for the wood matrix.

Hollow fibre-based liquid phase microextraction combined with high-performance liquid chromatography for the analysis of flavonoids in Echinophora platyloba DC. and Mentha piperita.

PubMed

Hadjmohammadi, Mohammadreza; Karimiyan, Hanieh; Sharifi, Vahid

2013-11-15

A simple, inexpensive and efficient three phase hollow fibre liquid phase microextraction (HF-LPME) technique combined with HPLC was used for the simultaneous determination of flavonoids in Echinophora platyloba DC. and Mentha piperita. Different factors affecting the HF-LPME procedure were investigated and optimised. The optimised extraction conditions were as follows: 1-octanol as an organic solvent, pHdonor=2, pHacceptor=9.75, stirring rate of 1000rpm, extraction time of 80min, without addition of salt. Under these conditions, the enrichment factors ranged between 146 and 311. The values of intra and inter-day relative standard deviations (RSD) were in the range of 3.18-6.00% and 7.25-11.00%, respectively. The limits of detection (LODs) ranged between 0.5 and 7.0ngmL(-1). Among the investigated flavonoids quercetin was found in E. platyloba DC. and luteolin was found in M. piperita. Concentration of quercetin and luteolin was 0.015 and 0.025mgg(-1) respectively. Copyright © 2013 Elsevier Ltd. All rights reserved.

Multifamily determination of pesticide residues in soya-based nutraceutical products by GC/MS-MS.

PubMed

Páleníková, Agneša; Martínez-Domínguez, Gerardo; Arrebola, Francisco Javier; Romero-González, Roberto; Hrouzková, Svetlana; Frenich, Antonia Garrido

2015-04-15

An analytical method based on a modified QuEChERS extraction coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS) was evaluated for the determination of 177 pesticides in soya-based nutraceutical products. The QuEChERS method was optimised and different extraction solvents and clean-up approaches were tested, obtaining the most efficient conditions with a mixture of sorbents (PSA, C18, GBC and Zr-Sep(+)). Recoveries were evaluated at 10, 50 and 100 μg/kg and ranged between 70% and 120%. Precision was expressed as relative standard deviation (RSD), and it was evaluated for more than 160 pesticides as intra and inter-day precision, with values always below 20% and 25%, respectively. Limits of detection (LODs) ranged from 0.1 to 10 μg/kg, whereas limits of quantification (LOQs) from 0.5 to 20 μg/kg. The applicability of the method was proved by analysing soya-based nutraceuticals. Two pesticides were found in these samples, malathion and pyriproxyfen, at 11.1 and 1.5 μg/kg respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

Analysis of pesticides in soy milk combining solid-phase extraction and capillary electrophoresis-mass spectrometry.

PubMed

Hernández-Borges, Javier; Rodriguez-Delgado, Miguel Angel; García-Montelongo, Francisco J; Cifuentes, Alejandro

2005-06-01

In this work, the determination of a group of triazolopyrimidine sulfoanilide herbicides (cloransulam-methyl, metosulam, flumetsulam, florasulam, and diclosulam) in soy milk by capillary electrophoresis-mass spectrometry (CE-MS) is presented. The main electrospray interface (ESI) parameters (nebulizer pressure, dry gas flow rate, dry gas temperature, and composition of the sheath liquid) are optimized using a central composite design. To increase the sensitivity of the CE-MS method, an off-line sample preconcentration procedure based on solid-phase extraction (SPE) is combined with an on-line stacking procedure (i.e. normal stacking mode, NSM). Samples could be injected for up to 100 s, providing limits of detection (LODs) down to 74 microg/L, i.e., at the low ppb level, with relative standard deviation values (RSD,%) between 3.8% and 6.4% for peak areas on the same day, and between 6.5% and 8.1% on three different days. The usefulness of the optimized SPE-NSM-CE-MS procedure is demonstrated through the sensitive quantification of the selected pesticides in soy milk samples.

Estimation of L-dopa from Mucuna pruriens LINN and formulations containing M. pruriens by HPTLC method.

PubMed

Modi, Ketan Pravinbhai; Patel, Natvarlal Manilal; Goyal, Ramesh Kishorilal

2008-03-01

A selective, precise, and accurate high-performance thin-layer chromatographic (HPTLC) method has been developed for the analysis of L-dopa in Mucuna pruriens seed extract and its formulations. The method involves densitometric evaluation of L-dopa after resolving it by HPTLC on silica gel plates with n-butanol-acetic acid-water (4.0+1.0+1.0, v/v) as the mobile phase. Densitometric analysis of L-dopa was carried out in the absorbance mode at 280 nm. The relationship between the concentration of L-dopa and corresponding peak areas was found to be linear in the range of 100 to 1200 ng/spot. The method was validated for precision (inter and intraday), repeatability, and accuracy. Mean recovery was 100.30%. The relative standard deviation (RSD) values of the precision were found to be in the range 0.64-1.52%. In conclusion, the proposed TLC method was found to be precise, specific and accurate and can be used for identification and quantitative determination of L-dopa in herbal extract and its formulations.

Dissipation, transfer and safety evaluation of emamectin benzoate in tea.

PubMed

Zhou, Li; Luo, Fengjian; Zhang, Xinzhong; Jiang, Yaping; Lou, Zhengyun; Chen, Zongmao

2016-07-01

The dissipation and residue of emamectin benzoate in tea leaves and the residue transfer from tea leaves to tea brew were investigated by modified QuEChERS (quick, easy, cheap, effective, rugged and safe) combined with ultra performance liquid chromatography tandem mass (UPLC-MS/MS). The average recoveries ranged 85.3-101.3% with relative standard deviation (RSD) less than 15%. The limits of quantification (LOQ) were 0.005mgkg(-1) in tea leaves and 0.0004mgL(-1) in brew. Emamectin benzoate dissipated rapidly in tea with half-life (t1/2) of 1.0-1.3days. The terminal residues of emamectin benzoate were less than 0.062mgkg(-1). The leaching rate of emamectin benzoate from freshly-made tea to brew was <5%. The risk of emamectin benzoate at the recommended dosage was negligible to humans depending on risk quotient (RQ) value, that was lower than 1 significantly. This study could provide guidance for the safe use of emamectin benzoate and serve as a reference for the establishment of maximum residue limits (MRLs) in China. Copyright © 2016. Published by Elsevier Ltd.

A simple method for determination of carmine in food samples based on cloud point extraction and spectrophotometric detection.

PubMed

Heydari, Rouhollah; Hosseini, Mohammad; Zarabi, Sanaz

2015-01-01

In this paper, a simple and cost effective method was developed for extraction and pre-concentration of carmine in food samples by using cloud point extraction (CPE) prior to its spectrophotometric determination. Carmine was extracted from aqueous solution using Triton X-100 as extracting solvent. The effects of main parameters such as solution pH, surfactant and salt concentrations, incubation time and temperature were investigated and optimized. Calibration graph was linear in the range of 0.04-5.0 μg mL(-1) of carmine in the initial solution with regression coefficient of 0.9995. The limit of detection (LOD) and limit of quantification were 0.012 and 0.04 μg mL(-1), respectively. Relative standard deviation (RSD) at low concentration level (0.05 μg mL(-1)) of carmine was 4.8% (n=7). Recovery values in different concentration levels were in the range of 93.7-105.8%. The obtained results demonstrate the proposed method can be applied satisfactory to determine the carmine in food samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Rapid determination of pyridine derivatives by dispersive liquid-liquid microextraction coupled with gas chromatography/gas sensor based on nanostructured conducting polypyrrole.

PubMed

Pirsa, Sajad; Alizadeh, Naader

2011-12-15

Polypyrrole (PPy) gas sensor has been prepared by polymerization of pyrrole on surfaces of commercial polymer fibers in the presence of an oxidizing agent. The sensing behavior of PPy gas sensor was investigated in the presence of pyridine derivatives. The resistive responses of the PPy gas sensor to pyridine derivatives were in the order of quinoline>pyridine>4-methyl pyridine and 2-methyl pyridine. The PPy gas sensor was used as gas chromatography (GC) detector and exhibited linear responses to pyridine derivatives in the ranges 40-4,000 ng. Dispersive liquid-liquid microextraction (DLLME) combined with GC/PPy gas sensor has been developed for simultaneous determination of pyridine derivatives and quinoline. The purposed method was used for determination of pyridine derivatives from cigarette smoke. The GC runs were completed in 4 min. The reproducibility of this method is suitable and good standard deviations were obtained. RSD value is less than 10% for all analytes. Copyright © 2011 Elsevier B.V. All rights reserved.

Evaluation of width and width uniformity of near-field electrospinning printed micro and sub-micrometer lines based on optical image processing

NASA Astrophysics Data System (ADS)

Zhao, Libo; Xia, Yong; Hebibul, Rahman; Wang, Jiuhong; Zhou, Xiangyang; Hu, Yingjie; Li, Zhikang; Luo, Guoxi; Zhao, Yulong; Jiang, Zhuangde

2018-03-01

This paper presents an experimental study using image processing to investigate width and width uniformity of sub-micrometer polyethylene oxide (PEO) lines fabricated by near-filed electrospinning (NFES) technique. An adaptive thresholding method was developed to determine the optimal gray values to accurately extract profiles of printed lines from original optical images. And it was proved with good feasibility. The mechanism of the proposed thresholding method was believed to take advantage of statistic property and get rid of halo induced errors. Triangular method and relative standard deviation (RSD) were introduced to calculate line width and width uniformity, respectively. Based on these image processing methods, the effects of process parameters including substrate speed (v), applied voltage (U), nozzle-to-collector distance (H), and syringe pump flow rate (Q) on width and width uniformity of printed lines were discussed. The research results are helpful to promote the NFES technique for fabricating high resolution micro and sub-micro lines and also helpful to optical image processing at sub-micro level.

Application of maltodextrin as chiral selector in capillary electrophoresis for quantification of amlodipine enantiomers in commercial tablets.

PubMed

Nojavan, Saeed; Pourmoslemi, Shabnam; Behdad, Hamideh; Fakhari, Ali Reza; Mohammadi, Ali

2014-08-01

Maltodextrin was investigated as a chiral selector in capillary electrophoresis (CE) analysis of amlodipine (AM) enantiomers. For development of a stereoselective CE method, various effective parameters on the enantioseparation were optimized. The best results were achieved on an uncoated fused silica capillary at 20 °C using phosphate buffer (100 mM, pH 4) containing 10% w/v maltodextrin (dextrose equivalent value 4-7). The UV detector was set at 214 nm and a constant voltage of 20 kV was applied. The range of quantitation was 2.5-250 µg/mL (R(2)  > 0.999) for both enantiomers. Intra- (n = 5) and interday (n = 3) relative standard deviation (RSD) values were less than 7%. The limits of quantitation and detection were 1.7 µg/mL and 0.52 µg/mL, respectively. Recoveries of R(+) and S(-) enantiomers from tablet matrix were 97.2% and 97.8%, respectively. The method was applied for the quantification of AM enantiomers in commercial tablets. Also, the enantioseparation capability of heparin was evaluated and the results showed that heparin did not have any chiral selector activity in this study. Copyright © 2014 Wiley Periodicals, Inc.

Accurate quantification of creatinine in serum by coupling a measurement standard to extractive electrospray ionization mass spectrometry

NASA Astrophysics Data System (ADS)

Huang, Keke; Li, Ming; Li, Hongmei; Li, Mengwan; Jiang, You; Fang, Xiang

2016-01-01

Ambient ionization (AI) techniques have been widely used in chemistry, medicine, material science, environmental science, forensic science. AI takes advantage of direct desorption/ionization of chemicals in raw samples under ambient environmental conditions with minimal or no sample preparation. However, its quantitative accuracy is restricted by matrix effects during the ionization process. To improve the quantitative accuracy of AI, a matrix reference material, which is a particular form of measurement standard, was coupled to an AI technique in this study. Consequently the analyte concentration in a complex matrix can be easily quantified with high accuracy. As a demonstration, this novel method was applied for the accurate quantification of creatinine in serum by using extractive electrospray ionization (EESI) mass spectrometry. Over the concentration range investigated (0.166 ~ 1.617 μg/mL), a calibration curve was obtained with a satisfactory linearity (R2 = 0.994), and acceptable relative standard deviations (RSD) of 4.6 ~ 8.0% (n = 6). Finally, the creatinine concentration value of a serum sample was determined to be 36.18 ± 1.08 μg/mL, which is in excellent agreement with the certified value of 35.16 ± 0.39 μg/mL.

New method for the determination of metolachlor and buprofezin in natural water using orthophthalaldehyde by thermochemically-induced fluorescence derivatization (TIFD).

PubMed

Mendy, Alphonse; Thiaré, Diène Diégane; Sambou, Souleymane; Khonté, Abdourahmane; Coly, Atanasse; Gaye-Seye, Mame Diabou; Delattre, François; Tine, Alphonse

2016-05-01

Herbicide metolachlor (MET) and insecticide buprofezin (BUP) were determined in natural waters by means of a newly-developed, simple and sensitive thermochemically-induced fluorescence derivatization (TIFD) method. The TIFD approach is based on the thermolysis transformation of naturally non-fluorescent pesticides into fluorescent complex O-phthalaldehyde-thermoproduct(s) in water at 70°C for MET and at 80°C for BUP. The TIFD method was optimized with respect to the temperature, pH, complex formation kinetic and pesticides concentrations. The limit of detection (LOD=0.8ngmL(-1) for MET and 3.0ngmL(-1) for BUP) and quantification (LOQ=2.6ngmL(-1) for MET and 9.5 ngmL(-1) for BUP) values were low, and the relative standard deviation (RSD) values were small (between 1.2% and 1.8%), which indicates a good analytical sensitivity and a great repeatability of TIFD method. Recovery studies were performed on spiked well, sea and draining waters samples collected in the Niayes area by using the solid phase extraction (SPE) procedure. Satisfactory recovery results (84-118%) were obtained for the determination of MET and BUP in these natural waters. Copyright © 2016 Elsevier B.V. All rights reserved.

Highly Sensitive and Reproducible SERS Sensor for Biological pH Detection Based on a Uniform Gold Nanorod Array Platform.

PubMed

Bi, Liyan; Wang, Yunqing; Yang, Ying; Li, Yuling; Mo, Shanshan; Zheng, Qingyin; Chen, Lingxin

2018-05-09

Conventional research on surface-enhanced Raman scattering (SERS)-based pH sensors often depends on nanoparticle aggregation, whereas the variability in nanoparticle aggregation gives rise to poor repeatability in the SERS signal. Herein, we fabricated a gold nanorod array platform via an efficient evaporative self-assembly method. The platform exhibits great SERS sensitivity with an enhancement factor of 5.6 × 10 7 and maintains excellent recyclability and reproducibility with relative standard deviation (RSD) values of less than 8%. On the basis of the platform, we developed a highly sensitive bovine serum albumin (BSA)-coated 4-mercaptopyridine (4-MPy)-linked (BMP) SERS-based pH sensor to report pH ranging from pH 3.0 to pH 8.0. The intensity ratio variation of 1004 and 1096 cm -1 in 4-MPy showed excellent pH sensitivity, which decreased as the surrounding pH increased. Furthermore, this BMP SERS-based pH sensor was employed to measure the pH value in C57BL/6 mouse blood. We have demonstrated that the pH sensor has great advantages such as good stability, reliability, and accuracy, which could be extended for the design of point-of-care devices.

Bromine isotope ratio measurements in seawater by multi-collector inductively coupled plasma-mass spectrometry with a conventional sample introduction system.

PubMed

de Gois, Jefferson S; Vallelonga, Paul; Spolaor, Andrea; Devulder, Veerle; Borges, Daniel L G; Vanhaecke, Frank

2016-01-01

A simple and accurate methodology for Br isotope ratio measurements in seawater by multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) with pneumatic nebulization for sample introduction was developed. The Br(+) signals could be measured interference-free at high mass resolution. Memory effects for Br were counteracted using 5 mmol L(-1) of NH4OH in sample, standard, and wash solutions. The major cation load of seawater was removed via cation exchange chromatography using Dowex 50WX8 resin. Subsequent Br preconcentration was accomplished via evaporation of the sample solution at 90 °C, which did not induce Br losses or isotope fractionation. Mass discrimination was corrected for by external correction using a Cl-matched standard measured in a sample-standard bracketing approach, although Sr, Ge, and Se were also tested as potential internal standards for internal correction for mass discrimination. The δ(81)Br (versus standard mean ocean bromide (SMOB)) values thus obtained for the NaBr isotopic reference material NIST SRM 977 and for IRMM BCR-403 seawater certified reference material are in agreement with literature values. For NIST SRM 977, the (81)Br/(79)Br ratio (0.97291) was determined with a precision ≤0.08‰ relative standard deviation (RSD).

Total reflection X-ray Fluorescence determination of interfering elements rubidium and uranium by profile fitting

NASA Astrophysics Data System (ADS)

Dhara, Sangita; Khooha, Ajay; Singh, Ajit Kumar; Tiwari, M. K.; Misra, N. L.

2018-06-01

Systematic studies to assess the analytical parameters obtained in the total reflection X-ray fluorescence (TXRF) determinations of interfering elements Rb and U using profile fitting are reported in the present manuscript. The X-ray lines Rb Kα and U Lα having serious spectral interference (ΔE = 218 eV), have been used as analytical lines. The intensities of these X-ray lines have been assessed using profile fitting. In order to compare the analytical results of Rb determinations in presence of U, with and without U excitation, synchrotron radiation was tuned to energy just above and below the U Labs edge. This approach shall excite both Rb Kα and U Lα simultaneously and Rb Kα selectively. Finally, the samples were also analyzed with a laboratory based TXRF spectrometer. The analytical results obtained in all these conditions were comparable. The authenticity of the results was assessed by analyzing U with respect to Rb in Rb2U(SO4)3, a standard reference material for U. The average precision obtained for TXRF determinations was below 3% (RSD, n = 3, 1σ) and the percent deviation of TXRF values from the expected values calculated on the basis of sample preparation was within 3%.

Quantification of genetically modified soybeans using a combination of a capillary-type real-time PCR system and a plasmid reference standard.

PubMed

Toyota, Akie; Akiyama, Hiroshi; Sugimura, Mitsunori; Watanabe, Takahiro; Kikuchi, Hiroyuki; Kanamori, Hisayuki; Hino, Akihiro; Esaka, Muneharu; Maitani, Tamio

2006-04-01

Because the labeling of grains and feed- and foodstuffs is mandatory if the genetically modified organism (GMO) content exceeds a certain level of approved genetically modified varieties in many countries, there is a need for a rapid and useful method of GMO quantification in food samples. In this study, a rapid detection system was developed for Roundup Ready Soybean (RRS) quantification using a combination of a capillary-type real-time PCR system, a LightCycler real-time PCR system, and plasmid DNA as the reference standard. In addition, we showed for the first time that the plasmid and genomic DNA should be similar in the established detection system because the PCR efficiencies of using plasmid DNA and using genomic DNA were not significantly different. The conversion factor (Cf) to calculate RRS content (%) was further determined from the average value analyzed in three laboratories. The accuracy and reproducibility of this system for RRS quantification at a level of 5.0% were within a range from 4.46 to 5.07% for RRS content and within a range from 2.0% to 7.0% for the relative standard deviation (RSD) value, respectively. This system rapidly monitored the labeling system and had allowable levels of accuracy and precision.

Direct lead isotope analysis in Hg-rich sulfides by LA-MC-ICP-MS with a gas exchange device and matrix-matched calibration.

PubMed

Zhang, Wen; Hu, Zhaochu; Günther, Detlef; Liu, Yongsheng; Ling, Wenli; Zong, Keqing; Chen, Haihong; Gao, Shan

2016-12-15

In situ Pb isotope data of sulfide samples measured by LA-MC-ICP-MS provide valuable geochemical information for studies of the origin and evolution of ore deposits. However, the severe isobaric interference of 204 Hg on 204 Pb and the lack of matrix-matched sulfide reference materials limit the precision of Pb isotopic analyses for Hg-rich sulfides. In this study, we observe that Hg forms vapor and can be completely removed from sample aerosol particles produced by laser ablation using a gas exchange device. Additionally, this device does not influence the signal intensities of Pb isotopes. The within-run precision, the external reproducibility and the analytical accuracy are significantly improved for the Hg-rich sulfide samples using this mercury-vapor-removing device. Matrix effects are observed when using silicate glass reference materials as the external standards to assess the relationship of mass fractionation factors between Tl and Pb in sulfide samples, resulting in a maximum deviation of ∼0.20% for 20x Pb/ 204 Pb. Matrix-matched reference materials are therefore required for the highly precise and accurate Pb isotope analyses of sulfide samples. We investigated two sulfide samples, MASS-1 (the Unites States Geological Survey reference materials) and Sph-HYLM (a natural sphalerite), as potential candidates. Repeated analyses of the two proposed sulfide reference materials by LA-MC-ICP-MS yield good external reproducibility of <0.04% (RSD, k = 2) for 20x Pb/ 206 Pb and <0.06% (RSD, k = 2) for 20x Pb/ 204 Pb with the exception of 20x Pb/ 204 Pb in MASS-1, which provided an external reproducibility of 0.24% (RSD, k = 2). Because the concentration of Pb in MASS-1 (76 μg g -1 ) is ∼5.2 times lower than that in Sph-HYLM (394 ± 264 μg g -1 ). The in situ analytical results of MASS-1 and Sph-HYLM are consistent with the values obtained by solution MC-ICP-MS, demonstrating the reliability and robustness of our analytical protocol. Copyright © 2016 Elsevier B.V. All rights reserved.

Fast determination of 3-ethenylpyridine as a marker of environmental tobacco smoke at trace level using direct atmospheric pressure chemical ionization tandem mass spectrometry

NASA Astrophysics Data System (ADS)

Jiang, Cheng-Yong; Sun, Shi-Hao; Zhang, Qi-Dong; Liu, Jun-Hui; Zhang, Jian-Xun; Zong, Yong-Li; Xie, Jian-Ping

2013-03-01

A method with atmospheric pressure chemical ionization tandem mass spectrometry (APCI-MS/MS) was developed and applied to direct analysis of Environmental Tobacco Smoke (ETS), using 3-ethenylpyridine (3-EP) as a vapour-phase marker. In this study, the ion source of APCI-MS/MS was modified and direct analysis of gas sample was achieved by the modified instrument. ETS samples were directly introduced, via an atmospheric pressure inlet, into the APCI source. Ionization was carried out in positive-ion APCI mode and 3-EP was identified by both full scan mode and daughter scan mode. Quantification of 3-EP was performed by multiple reaction monitoring (MRM) mode. The calibration curve was obtained in the range of 1-250 ng L-1 with a satisfactory regression coefficient of 0.999. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.5 ng L-1 and 1.6 ng L-1, respectively. The precision of the method, calculated as relative standard deviation (RSD), was characterized by repeatability (RSD 3.92%) and reproducibility (RSD 4.81%), respectively. In real-world ETS samples analysis, compared with the conventional GC-MS method, the direct APCI-MS/MS has shown better reliability and practicability in the determination of 3-EP at trace level. The developed method is simple, fast, sensitive and repeatable; furthermore, it could provide an alternative way for the determination of other volatile pollutants in ambient air at low levels.

Preparation of three-dimensional mesoporous polymer in situ polymerization solid phase microextraction fiber and its application to the determination of seven chlorophenols.

PubMed

Wang, Xuemei; Wang, Huan; Huang, Pengfei; Ma, Xiaomin; Lu, Xiaoquan; Du, Xinzhen

2017-01-06

A superior solid-phase microextraction (SPME) fiber-coating material, three dimensional order mesoporous polymers with Ia-3d bicontinuous cubic structure (3D-OMPs) was in situ coated on a stainless steel wire by solvent evaporation induced self-assembly (EISA) and thermo-polymerization. Fourier-transform infrared spectrometry (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), small-angel X-ray diffraction (SAXRD), N 2 adsorption-desorption transmission, and thermogravimetry analysis (TGA) were applied to the characterization of the synthesized 3D-OMPs coating. The performance and feasibility of the homemade fiber was evaluated through direct immersion (DI) SPME followed by high-performance liquid chromatography-UV detector (HPLC-UV) for the simultaneous extraction of seven chlorophenols in water samples. Under the optimum conditions, the prepared fiber exhibited excellent extraction properties as compared to three commercial fibers, the DI-SPME-HPLC-UV method showed low limits of detection (0.32-1.85μgL -1 ), wide linear ranges (5.0-1000μgL -1 ), and acceptable reproducibility (relative standard deviation, RSD<7.6% for one fiber, RSD<8.9% for fiber to fiber). Moreover, the method was further successfully applied to the analysis of seven CPs in real samples with good recoveries (80.5-99.5%) and satisfactory precisions (RSD<9.2%). It was confirmed that the proposed method has high sensitivity, outstanding selectivity and good reproducibility to the determination of trace CPs in the environmental water. Copyright © 2016 Elsevier B.V. All rights reserved.

The 25th anniversary of the retrograde suction decompression technique (Dallas technique) for the surgical management of paraclinoid aneurysms: historical background, systematic review, and pooled analysis of the literature.

PubMed

Flores, Bruno C; White, Jonathan A; Batjer, H Hunt; Samson, Duke S

2018-05-04

OBJECTIVE Paraclinoid internal carotid artery (ICA) aneurysms frequently require temporary occlusion to facilitate safe clipping. Brisk retrograde flow through the ophthalmic artery and cavernous ICA branches make simple trapping inadequate to soften the aneurysm. The retrograde suction decompression (RSD), or Dallas RSD, technique was described in 1990 in an attempt to overcome some of those treatment limitations. A frequent criticism of the RSD technique is an allegedly high risk of cervical ICA dissection. An endovascular modification was introduced in 1991 (endovascular RSD) but no studies have compared the 2 RSD variations. METHODS The authors performed a systematic review of MEDLINE/PubMed and Web of Science and identified all studies from 1990-2016 in which either Dallas RSD or endovascular RSD was used for treatment of paraclinoid aneurysms. A pooled analysis of the data was completed to identify important demographic and treatment-specific variables. The primary outcome measure was defined as successful aneurysm obliteration. Secondary outcome variables were divided into overall and RSD-specific morbidity and mortality rates. RESULTS Twenty-six RSD studies met the inclusion criteria (525 patients, 78.9% female). The mean patient age was 53.5 years. Most aneurysms were unruptured (56.6%) and giant (49%). The most common presentations were subarachnoid hemorrhage (43.6%) and vision changes (25.3%). The aneurysm obliteration rate was 95%. The mean temporary occlusion time was 12.7 minutes. Transient or permanent morbidity was seen in 19.9% of the patients. The RSD-specific complication rate was low (1.3%). The overall mortality rate was 4.2%, with 2 deaths (0.4%) attributable to the RSD technique itself. Good or fair outcome were reported in 90.7% of the patients. Aneurysm obliteration rates were similar in the 2 subgroups (Dallas RSD 94.3%, endovascular RSD 96.3%, p = 0.33). Despite a higher frequency of complex (giant or ruptured) aneurysms, Dallas RSD was associated with lower RSD-related morbidity (0.6% vs 2.9%, p = 0.03), compared with the endovascular RSD subgroup. There was a trend toward higher mortality in the endovascular RSD subgroup (6.4% vs 3.1%, p = 0.08). The proportion of patients with poor neurological outcome at last follow-up was significantly higher in the endovascular RSD group (15.4% vs 7.2%, p < 0.01). CONCLUSIONS The treatment of paraclinoid ICA aneurysms using the RSD technique is associated with high aneurysm obliteration rates, good long-term neurological outcome, and low RSD-related morbidity and mortality. Review of the RSD literature showed no evidence of a higher complication rate associated with the Dallas technique compared with similar endovascular methods. On a subgroup analysis of Dallas RSD and endovascular RSD, both groups achieved similar obliteration rates, but a lower RSD-related morbidity was seen in the Dallas technique subgroup. Twenty-five years after its initial publication, RSD remains a useful neurosurgical technique for the management of large and giant paraclinoid aneurysms.

Flow electrochemical biosensors based on enzymatic porous reactor and tubular detector of silver solid amalgam.

PubMed

Josypčuk, Bohdan; Barek, Jiří; Josypčuk, Oksana

2013-05-17

A flow amperometric enzymatic biosensor for the determination of glucose was constructed. The biosensor consists of a flow reactor based on porous silver solid amalgam (AgSA) and a flow tubular detector based on compact AgSA. The preparation of the sensor and the determination of glucose occurred in three steps. First, a self-assembled monolayer of 11-mercaptoundecanoic acid (MUA) was formed at the porous surface of the reactor. Second, enzyme glucose oxidase (GOx) was covalently immobilized at MUA-layer using N-ethyl-N'-(3-dimethylaminopropyl) carboimide and N-hydroxysuccinimide chemistry. Finally, a decrease of oxygen concentration (directly proportional to the concentration of glucose) during enzymatic reaction was amperometrically measured on the tubular detector under flow injection conditions. The following parameters of glucose determination were optimized with respect to amperometric response: composition of the mobile phase, its concentration, the potential of detection and the flow rate. The calibration curve of glucose was linear in the concentration range of 0.02-0.80 mmol L(-1) with detection limit of 0.01 mmol L(-1). The content of glucose in the sample of honey was determined as 35.5±1.0 mass % (number of the repeated measurements n=7; standard deviation SD=1.2%; relative standard deviation RSD=3.2%) which corresponds well with the declared values. The tested biosensor proved good long-term stability (77% of the current response of glucose was retained after 35 days). Copyright © 2013 Elsevier B.V. All rights reserved.

Endovascular ultrasound for renal sympathetic denervation in patients with therapy-resistant hypertension not responding to radiofrequency renal sympathetic denervation.

PubMed

Stiermaier, Thomas; Okon, Thomas; Fengler, Karl; Mueller, Ulrike; Hoellriegel, Robert; Schuler, Gerhard; Desch, Steffen; Lurz, Philipp

2016-06-12

Recent studies have reported a considerable number of non-responders after renal sympathetic de-nervation (RSD) with radiofrequency technology. Here we report our results of repeat RSD using ultrasound in these patients. A cohort study was performed in patients who underwent ultrasound RSD after non-response to RSD with radiofrequency. Non-response was defined as mean daytime systolic blood pressure ≥140 mmHg and/or a reduction of ≤10 mmHg in ambulatory blood pressure measurement (ABPM) ≥6 months after radiofrequency denervation. ABPM was recorded at baseline, post radiofrequency RSD as well as at three and six months post ultrasound RSD. A total of 24 non-responders underwent retreatment with the ultrasound device at a mean 15.3±8.2 months after radiofrequency RSD. Ultrasound RSD was performed successfully in all patients without severe adverse events. Mean daytime systolic blood pressure changed from 161.7±14.6 mmHg at baseline to 158.5±9.5 mmHg post radiofrequency RSD and to 150.5±10.4 mmHg and 151.6±11.0 mmHg at three and six months, respectively, post ultrasound RSD (p<0.01 with repeated measures analysis of variance). The main results of post hoc testing were as follows: baseline versus post radiofrequency RSD, p=0.83; baseline versus three months post ultrasound RSD, p=0.01; and baseline versus six months post ultrasound RSD, p=0.04. Ultrasound RSD appears to be safe and an effective therapeutic approach in patients not responding to previous RSD with radiofrequency technology.

The Caenorhabditis elegans rsd-2 and rsd-6 genes are required for chromosome functions during exposure to unfavorable environments.

PubMed

Han, Wang; Sundaram, Prema; Kenjale, Himanshu; Grantham, James; Timmons, Lisa

2008-04-01

In Caenorhabditis elegans, exogenous dsRNA can elicit systemic RNAi, a process that requires the function of many genes. Considering that the activities of many of these genes are also required for normal development, it is surprising that exposure to high concentrations of dsRNA does not elicit adverse consequences to animals. Here, we report inducible phenotypes in attenuated C. elegans strains reared in environments that include nonspecific dsRNA and elevated temperature. Under these conditions, chromosome integrity is compromised in RNAi-defective strains harboring mutations in rsd-2 or rsd-6. Specifically, rsd-2 mutants display defects in transposon silencing, while meiotic chromosome disjunction is affected in rsd-6 mutants. RSD-2 proteins localize to multiple cellular compartments, including the nucleolus and cytoplasmic compartments that, in part, are congruent with calreticulin and HAF-6. We considered that the RNAi defects in rsd-2 mutants might have relevance to membrane-associated functions; however, endomembrane compartmentalization and endocytosis/exocytosis markers in rsd-2 and rsd-6 mutants appear normal. The mutants also possess environmentally sensitive defects in cell-autonomous RNAi elicited from transgene-delivered dsRNAs. Thus, the ultimate functions of rsd-2 and rsd-6 in systemic RNAi are remarkably complex and environmentally responsive.

Digital movie-based on automatic titrations.

PubMed

Lima, Ricardo Alexandre C; Almeida, Luciano F; Lyra, Wellington S; Siqueira, Lucas A; Gaião, Edvaldo N; Paiva Junior, Sérgio S L; Lima, Rafaela L F C

2016-01-15

This study proposes the use of digital movies (DMs) in a flow-batch analyzer (FBA) to perform automatic, fast and accurate titrations. The term used for this process is "Digital movie-based on automatic titrations" (DMB-AT). A webcam records the DM during the addition of the titrant to the mixing chamber (MC). While the DM is recorded, it is decompiled into frames ordered sequentially at a constant rate of 26 frames per second (FPS). The first frame is used as a reference to define the region of interest (ROI) of 28×13pixels and the R, G and B values, which are used to calculate the Hue (H) values for each frame. The Pearson's correlation coefficient (r) is calculated between the H values of the initial frame and each subsequent frame. The titration curves are plotted in real time using the r values and the opening time of the titrant valve. The end point is estimated by the second derivative method. A software written in C language manages all analytical steps and data treatment in real time. The feasibility of the method was attested by application in acid/base test samples and edible oils. Results were compared with classical titration and did not present statistically significant differences when the paired t-test at the 95% confidence level was applied. The proposed method is able to process about 117-128 samples per hour for the test and edible oil samples, respectively, and its precision was confirmed by overall relative standard deviation (RSD) values, always less than 1.0%. Copyright © 2015 Elsevier B.V. All rights reserved.

Crystal structure of the Escherichia coli regulator of sigma70, Rsd, in complex with sigma70 domain 4.

PubMed

Patikoglou, Georgia A; Westblade, Lars F; Campbell, Elizabeth A; Lamour, Valérie; Lane, William J; Darst, Seth A

2007-09-21

The Escherichia coli Rsd protein binds tightly and specifically to the RNA polymerase (RNAP) sigma(70) factor. Rsd plays a role in alternative sigma factor-dependent transcription by biasing the competition between sigma(70) and alternative sigma factors for the available core RNAP. Here, we determined the 2.6 A-resolution X-ray crystal structure of Rsd bound to sigma(70) domain 4 (sigma(70)(4)), the primary determinant for Rsd binding within sigma(70). The structure reveals that Rsd binding interferes with the two primary functions of sigma(70)(4), core RNAP binding and promoter -35 element binding. Interestingly, the most highly conserved Rsd residues form a network of interactions through the middle of the Rsd structure that connect the sigma(70)(4)-binding surface with three cavities exposed on distant surfaces of Rsd, suggesting functional coupling between sigma(70)(4) binding and other binding surfaces of Rsd, either for other proteins or for as yet unknown small molecule effectors. These results provide a structural basis for understanding the role of Rsd, as well as its ortholog, AlgQ, a positive regulator of Pseudomonas aeruginosa virulence, in transcription regulation.

Crystal structure of the Escherichia coli regulator of σ70, Rsd, in complex with σ70 domain 4

PubMed Central

Patikoglou, Georgia A.; Westblade, Lars F.; Campbell, Elizabeth A.; Lamour, Valérie; Lane, William J.; Darst, Seth A.

2007-01-01

Summary The Escherichia coli Rsd protein binds tightly and specifically to the RNA polymerase (RNAP) σ70 factor. Rsd plays a role in alternative σ factor-dependent transcription by biasing the competition between σ70 and alternative σ factors for the available core RNAP. Here, we determined the 2.6 Å-resolution X-ray crystal structure of Rsd bound to σ70 domain 4 (σ704), the primary determinant for Rsd binding within σ70. The structure reveals that Rsd binding interferes with the two primary functions of σ704, core RNAP binding and promoter –35 element binding. Interestingly, the most highly conserved Rsd residues form a network of interactions through the middle of the Rsd structure that connect the σ704-binding surface with three cavities exposed on distant surfaces of Rsd, suggesting functional coupling between σ704 binding and other binding surfaces of Rsd, either for other proteins or for as yet unknown small molecule effectors. These results provide a structural basis for understanding the role of Rsd, as well as its ortholog, AlgQ, a positive regulator of Pseudomonas aeruginosa virulence, in transcription regulation. PMID:17681541

[Cloning and characterization of a novel rat gene RSD-7 differentially expressed in testis].

PubMed

Zhang, Xiao-dong; Gou, Da-wei; Miao, Shi-ying; Zhang, Jian-chao; Zong, Shu-dong; Wang, Lin-fang

2003-06-01

To isolate and identify the differentially expressed genes in spermatogenesis for the understanding molecular mechanism of spermatogenesis. Screening of the cDNA library, Northern blot, expression and purification in E. coli with GST expression system, immunocytochemical staining of testis sections were used. (1) A cDNA fragment designated as RSD-7 was isolated from rat testis cDNA library. It was 1,238 bp in length, coding a protein of 232 amino acids with the GenBank accession number AF315467. The encoding protein of RSD-7 cDNA had a Ubiquitin-like domain. (2) Northern blot indicated that RSD-7 was uniquely expressed in rat testis, and in the testis RSD-7 emerged on the 30th postnatal day and expressed until 120th postnatal day. (3) Expression and purification of RSD-7 protein in E. coli with GST expression system and were used to obtain anti-RSD-7 antibody. (4) Immunolocalization of RSD-7 in rat testis revealed that it is expressed only in Sertoli cells. Transcription pattern of RSD-7 and localization of RSD-7 protein in testis have been made, which established the base for the functional study of RSD-7.

Caenorhabditis elegans RSD-2 and RSD-6 promote germ cell immortality by maintaining small interfering RNA populations.

PubMed

Sakaguchi, Aisa; Sarkies, Peter; Simon, Matt; Doebley, Anna-Lisa; Goldstein, Leonard D; Hedges, Ashley; Ikegami, Kohta; Alvares, Stacy M; Yang, Liwei; LaRocque, Jeannine R; Hall, Julie; Miska, Eric A; Ahmed, Shawn

2014-10-14

Germ cells are maintained in a pristine non-aging state as they proliferate over generations. Here, we show that a novel function of the Caenorhabditis elegans RNA interference proteins RNAi spreading defective (RSD)-2 and RSD-6 is to promote germ cell immortality at high temperature. rsd mutants cultured at high temperatures became progressively sterile and displayed loss of small interfering RNAs (siRNAs) that target spermatogenesis genes, simple repeats, and transposons. Desilencing of spermatogenesis genes occurred in late-generation rsd mutants, although defective spermatogenesis was insufficient to explain the majority of sterility. Increased expression of repetitive loci occurred in both germ and somatic cells of late-generation rsd mutant adults, suggesting that desilencing of many heterochromatic segments of the genome contributes to sterility. Nuclear RNAi defective (NRDE)-2 promotes nuclear silencing in response to exogenous double-stranded RNA, and our data imply that RSD-2, RSD-6, and NRDE-2 function in a common transgenerational nuclear silencing pathway that responds to endogenous siRNAs. We propose that RSD-2 and RSD-6 promote germ cell immortality at stressful temperatures by maintaining transgenerational epigenetic inheritance of endogenous siRNA populations that promote genome silencing.

Caenorhabditis elegans RSD-2 and RSD-6 promote germ cell immortality by maintaining small interfering RNA populations

PubMed Central

Sakaguchi, Aisa; Sarkies, Peter; Simon, Matt; Doebley, Anna-Lisa; Goldstein, Leonard D.; Hedges, Ashley; Ikegami, Kohta; Alvares, Stacy M.; Yang, Liwei; LaRocque, Jeannine R.; Hall, Julie; Miska, Eric A.; Ahmed, Shawn

2014-01-01

Germ cells are maintained in a pristine non-aging state as they proliferate over generations. Here, we show that a novel function of the Caenorhabditis elegans RNA interference proteins RNAi spreading defective (RSD)-2 and RSD-6 is to promote germ cell immortality at high temperature. rsd mutants cultured at high temperatures became progressively sterile and displayed loss of small interfering RNAs (siRNAs) that target spermatogenesis genes, simple repeats, and transposons. Desilencing of spermatogenesis genes occurred in late-generation rsd mutants, although defective spermatogenesis was insufficient to explain the majority of sterility. Increased expression of repetitive loci occurred in both germ and somatic cells of late-generation rsd mutant adults, suggesting that desilencing of many heterochromatic segments of the genome contributes to sterility. Nuclear RNAi defective (NRDE)-2 promotes nuclear silencing in response to exogenous double-stranded RNA, and our data imply that RSD-2, RSD-6, and NRDE-2 function in a common transgenerational nuclear silencing pathway that responds to endogenous siRNAs. We propose that RSD-2 and RSD-6 promote germ cell immortality at stressful temperatures by maintaining transgenerational epigenetic inheritance of endogenous siRNA populations that promote genome silencing. PMID:25258416

Rapid Quantitative Analysis of Naringenin in the Fruit Bodies of Inonotus vaninii by Two-phase Acid Hydrolysis Followed by Reversed Phase-high Performance Liquid Chromatography-ultra Violet.

PubMed

Guohua, Xia; Pan, Ruirong; Bao, Rui; Ge, Yanru; Zhou, Cunshan; Shen, Yuping

2017-01-01

Sanghuang is one of mystical traditional Chinese medicines recorded earliest 2000 years ago, that included various fungi of Inonotus genus and was well-known for antitumor effect in modern medicine. Inonotus vaninii is grown in natural forest of Northeastern China merely and used as Sanghuang commercially, but it has no quality control specification until now. This study was to establish a rapid method of two-phase acid hydrolysis followed by reversed phase-high performance liquid chromatography-ultra violet (RP-HPLC-UV) to quantify naringenin in the fruit body of I. vaninii . Sample solution was prepared by pretreatment of raw material in two-phase acid hydrolysis and the hydrolysis technology was optimized. After reconstitution, analysis was performed using RP-HPLC-UV. The method validation was investigated and the naringenin content of sample and comparison were determined. The naringenin was obtained by two-phase acid hydrolysis method, namely, 10.0 g of raw material was hydrolyzed in 200 mL of 1% sulfuric acid aqueous solution (v/v) and 400 mL of chloroform in oil bath at 110°C for 2 h. Good linearity ( r = 0.9992) was achieved between concentration of analyte and peak area. The relative standard deviation (RSD) of precision was 2.47% and the RSD of naringenin contents for repeatability was 3.13%. The accuracy was supported with recoveries at 96.37%, 97.30%, and 99.31%. The sample solution prepared using the proposed method contained higher content of naringenin than conventional method and was stable for 8 h. Due to the high efficiency of sample preparation and high reliability of the HPLC method, it is feasible to use this method for routine analysis of naringenin in the fungus. A convenient two-phase acid hydrolysis was employed to produce naringenin from raw material, and then an efficient and reliable reversed phase-high performance liquid chromatography-ultra violet method was established to monitor naringenin in the fruit bodies of Inonotus vaninii . The newly established method could be used to control the quality of the herb. Abbreviations used: RP-HPLC-UV: Reversed Phase-High Performance Liquid Chromatography-Ultra Violet, RSD: Relative Standard Deviation, EtOAc: Ethyl acetate, ACN: Acetonitrile, MeOH: Methanol, RH: Relative Humility.

Comparison of Digestion Methods for the Determination of Trace Elements and Heavy Metals in Human Hair and Nails

PubMed Central

Ishak, Ismarulyusda; Rosli, Farah Dayana; Mohamed, Jamaludin; Mohd Ismail, Muhammad Faiz

2015-01-01

Background Microwave is the most reliable sample digestion method. However, it requires expensive microwave digester automation and has relatively low productivity. In this study, three non-automated digestion methods, i.e. wet acid digestion using nitric acid (HNO3) and hydrogen peroxide (H2O2), wet acid digestion using HNO3, and dry washing, are compared in order to determine the best approach. Methods Certified reference material IAEA-086 (International Atomic Energy Agency, Austria) and hair and nail samples from 20 female students of Universiti Kebangsaan Malaysia, aged 19 to 30 years, were collected and analysed using the three digestion methods. Results For hair samples, analysis of variance of repeated measures showed significant differences in the level of all elements (P < 0.001) between the three methods. For nail samples, only the copper (Cu) level showed no significant difference (P = 0.100) between methods. Wet acid digestion using HNO3 and H2O2 showed the best within- and between-run relative standard deviation (RSD) values, with within-run RSD for all elements, except for selenium (Se), < 5%. The between-run precision ranges from 6.14% to 17.96% for hair and from 3.53% to 11.52% for nail samples. Wet acid digestion using HNO3 and H2O2 showed both good accuracy and precision for manganese (Mn) and magnesium (Mg), with percentage recoveries of 110% and 96.9%, respectively. All elements show higher method detection limit (MDL) values than the previous study: 0.05 μg/g Mg for wet acid digestion using HNO3, 0.02 μg/g Se for wet acid digestion using HNO3 and H2O2, and 0.2 μg/g Mg for dry ash method. Conclusion Wet acid digestion using HNO3 and H2O2 proved to be the best method in terms of precision, accuracy, recovery, and MDL. However, only Mn and Mg showed adequate precision, accuracy, and percentage of recovery. PMID:28223880

Flavanol and procyanidin content (by degree of polymerization 1-10) of chocolate, cocoa liquors, cocoa powders, and cocoa extracts: first action 2012.24.

PubMed

Robbins, Rebecca J; Leonczak, Jadwiga; Li, Julia; Johnson, J Christopher; Collins, Tom; Kwik-Uribe, Catherine; Schmitz, Harold H

2013-01-01

An international collaborative study was conducted on an HPLC method with fluorescent detection for the determination of flavanols and procyanidins in chocolate and cocoa-containing materials. The sum of the oligomeric fractions with degree of polymerization 1-10 was the determined content value. Sample materials included dark and milk chocolates, cocoa powder, cocoa liquors, and cocoa extracts. The content ranged from approximately 2 to 500 mg/g (defatted basis). Thirteen laboratories--representing commercial, industrial, and academic institutions in six countries--participated in this interlaboratory study. Fourteen samples were sent as blind duplicates to the collaborators. Results for 12 laboratories yielded repeatability RSD (RSDr) values below 10% for all materials analyzed, ranging from 4.17 to 9.61%. Reproducibility RSD (RSDR) values ranged from 5.03 to 12.9% for samples containing 8.07 to 484.7 mg/g material analyzed. In one sample containing a low content of flavanols and procyanidins (approximately 2 mg/g), the RSDR was 17.68%.

The histidine phosphocarrier protein, HPr, binds to the highly thermostable regulator of sigma D protein, Rsd, and its isolated helical fragments.

PubMed

Neira, José L; Hornos, Felipe; Cozza, Concetta; Cámara-Artigas, Ana; Abián, Olga; Velázquez-Campoy, Adrián

2018-02-01

The phosphotransferase system (PTS) controls the preferential use of sugars in bacteria and it is also involved in other processes, such as chemotaxis. It is formed by a protein cascade in which the first two proteins are general (namely, EI and HPr) and the others are sugar-specific permeases. The Rsd protein binds specifically to the RNA polymerase (RNAP) σ 70 factor. We first characterized the conformational stability of Escherichia coli Rsd. And second, we delineated the binding regions of Streptomyces coelicolor, HPr sc , and E. coli Rsd, by using fragments derived from each protein. To that end, we used several biophysical probes, namely, fluorescence, CD, NMR, ITC and BLI. Rsd had a free energy of unfolding of 15 kcal mol -1 at 25 °C, and a thermal denaturation midpoint of 103 °C at pH 6.5. The affinity between Rsd and HPr sc was 2 μM. Interestingly enough, the isolated helical-peptides, comprising the third (RsdH3) and fourth (RsdH4) Rsd helices, also interacted with HPr sc in a specific manner, and with affinities similar to that of the whole Rsd. Moreover, the isolated peptide of HPr sc , HPr 9-30 , comprising the active site, His15, also was bound to intact Rsd with similar affinity. Therefore, binding between Rsd and HPr sc was modulated by the two helices H3 and H4 of Rsd, and the regions around the active site of HPr sc . This implies that specific fragments of Rsd and HPr sc can be used to interfere with other protein-protein interactions (PPIs) of each other protein. Copyright © 2018 Elsevier Inc. All rights reserved.

Distribution function approach to redshift space distortions. Part IV: perturbation theory applied to dark matter

NASA Astrophysics Data System (ADS)

Vlah, Zvonimir; Seljak, Uroš; McDonald, Patrick; Okumura, Teppei; Baldauf, Tobias

2012-11-01

We develop a perturbative approach to redshift space distortions (RSD) using the phase space distribution function approach and apply it to the dark matter redshift space power spectrum and its moments. RSD can be written as a sum over density weighted velocity moments correlators, with the lowest order being density, momentum density and stress energy density. We use standard and extended perturbation theory (PT) to determine their auto and cross correlators, comparing them to N-body simulations. We show which of the terms can be modeled well with the standard PT and which need additional terms that include higher order corrections which cannot be modeled in PT. Most of these additional terms are related to the small scale velocity dispersion effects, the so called finger of god (FoG) effects, which affect some, but not all, of the terms in this expansion, and which can be approximately modeled using a simple physically motivated ansatz such as the halo model. We point out that there are several velocity dispersions that enter into the detailed RSD analysis with very different amplitudes, which can be approximately predicted by the halo model. In contrast to previous models our approach systematically includes all of the terms at a given order in PT and provides a physical interpretation for the small scale dispersion values. We investigate RSD power spectrum as a function of μ, the cosine of the angle between the Fourier mode and line of sight, focusing on the lowest order powers of μ and multipole moments which dominate the observable RSD power spectrum. Overall we find considerable success in modeling many, but not all, of the terms in this expansion. This is similar to the situation in real space, but predicting power spectrum in redshift space is more difficult because of the explicit influence of small scale dispersion type effects in RSD, which extend to very large scales.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vlah, Zvonimir; Seljak, Uroš; Baldauf, Tobias

We develop a perturbative approach to redshift space distortions (RSD) using the phase space distribution function approach and apply it to the dark matter redshift space power spectrum and its moments. RSD can be written as a sum over density weighted velocity moments correlators, with the lowest order being density, momentum density and stress energy density. We use standard and extended perturbation theory (PT) to determine their auto and cross correlators, comparing them to N-body simulations. We show which of the terms can be modeled well with the standard PT and which need additional terms that include higher order correctionsmore » which cannot be modeled in PT. Most of these additional terms are related to the small scale velocity dispersion effects, the so called finger of god (FoG) effects, which affect some, but not all, of the terms in this expansion, and which can be approximately modeled using a simple physically motivated ansatz such as the halo model. We point out that there are several velocity dispersions that enter into the detailed RSD analysis with very different amplitudes, which can be approximately predicted by the halo model. In contrast to previous models our approach systematically includes all of the terms at a given order in PT and provides a physical interpretation for the small scale dispersion values. We investigate RSD power spectrum as a function of μ, the cosine of the angle between the Fourier mode and line of sight, focusing on the lowest order powers of μ and multipole moments which dominate the observable RSD power spectrum. Overall we find considerable success in modeling many, but not all, of the terms in this expansion. This is similar to the situation in real space, but predicting power spectrum in redshift space is more difficult because of the explicit influence of small scale dispersion type effects in RSD, which extend to very large scales.« less

Hybrid molecularly imprinted polymers synthesized with 3-aminopropyltriethoxysilane-methacrylic acid monomer for miniaturized solid-phase extraction: A new and economical sample preparation strategy for determination of acyclovir in urine.

PubMed

Yan, Hongyuan; Wang, Mingyu; Han, Yehong; Qiao, Fengxia; Row, Kyung Ho

2014-06-13

The miniaturized molecularly imprinted solid-phase extraction (mini-MISPE) coupled with high-performance liquid chromatography was proposed for the determination of acyclovir in urine. 1.5-mL tapered plastic centrifuge tube filled with hybrid molecularly imprinted polymers (HMIPs) was used as the cartridge of mini-MISPE, and the HMIPs synthesized with 3-aminopropyltriethoxy silane-methacrylic acid as monomer exhibited good recognition and selectivity for acyclovir. Under the optimized condition, good linear calibration was obtained in a range of 0.5-15μgmL(-1) with the correlation coefficient of 0.9994, and the recoveries at three spiked levels were 91.6-103.3% in urine with the relative standard deviation (RSD) of ≤3.5%. Excellent intra-day and inter-day repeatability were achieved with RSD of ≤2.6% and 4.0% in three different concentrations. This method combined the advantages of HMIPs and mini-MISPE, and it could become an alternative tool for analyzing the residues of acyclovir in complex urine matrices. Copyright © 2014 Elsevier B.V. All rights reserved.

Phytoscreening with SPME: Variability Analysis.

PubMed

Limmer, Matt A; Burken, Joel G

2015-01-01

Phytoscreening has been demonstrated at a variety of sites over the past 15 years as a low-impact, sustainable tool in delineation of shallow groundwater contaminated with chlorinated solvents. Collection of tree cores is rapid and straightforward, but low concentrations in tree tissues requires sensitive analytics. Solid-phase microextraction (SPME) is amenable to the complex matrix while allowing for solvent-less extraction. Accurate quantification requires the absence of competitive sorption, examined here both in laboratory experiments and through comprehensive examination of field data. Analysis of approximately 2,000 trees at numerous field sites also allowed testing of the tree genus and diameter effects on measured tree contaminant concentrations. Collectively, while these variables were found to significantly affect site-adjusted perchloroethylene (PCE) concentrations, the explanatory power of these effects was small (adjusted R(2) = 0.031). 90th quantile chemical concentrations in trees were significantly reduced by increasing Henry's constant and increasing hydrophobicity. Analysis of replicate tree core data showed no correlation between replicate relative standard deviation (RSD) and wood type or tree diameter, with an overall median RSD of 30%. Collectively, these findings indicate SPME is an appropriate technique for sampling and analyzing chlorinated solvents in wood and that phytoscreening is robust against changes in tree type and diameter.

Development of a solenoid pumped in situ zinc analyzer for environmental monitoring

USGS Publications Warehouse

Chapin, T.P.; Wanty, R.B.

2005-01-01

A battery powered submersible chemical analyzer, the Zn-DigiScan (Zn Digital Submersible Chemical Analyzer), has been developed for near real-time, in situ monitoring of zinc in aquatic systems. Microprocessor controlled solenoid pumps propel sample and carrier through an anion exchange column to separate zinc from interferences, add colorimetric reagents, and propel the reaction complex through a simple photometric detector. The Zn-DigiScan is capable of self-calibration with periodic injections of standards and blanks. The detection limit with this approach was 30 ??g L-1. Precision was 5-10% relative standard deviation (R.S.D.) below 100 ??g L-1, improving to 1% R.S.D. at 1000 ??g L-1. The linear range extended from 30 to 3000 ??g L-1. In situ field results were in agreement with samples analyzed by inductively coupled plasma mass spectrometry (ICPMS). This pump technology is quite versatile and colorimetric methods with complex online manipulations such as column reduction, preconcentration, and dilution can be performed with the DigiScan. However, long-term field deployments in shallow high altitude streams were hampered by air bubble formation in the photometric detector. ?? 2005 Elsevier B.V. All rights reserved.

Simultaneous determination of 11 bioactive compounds in Jaeumganghwa-tang by high performance liquid chromatography-diode array detection

PubMed Central

Yun, Bo-Ra; Weon, Jin Bae; Lee, Jiwoo; Eom, Min Rye; Ma, Choong Je

2014-01-01

Background: Jaeumganghwa-tang (JEGH) is a traditional Korean herbal medicine for the treatment of chronic bronchitis, nephritis and diabetes mellitus. Objective: A high performance liquid chromatography-diode array detector (HPLC-DAD) method was developed for simultaneous determination of 11 major compounds such as 5- hydroxymethylfurfural, mangiferin, paeoniflorin, nodakenin, naringin, hesperidin, decursinol, berberine, glycyrrhizin, atractylenolide III and decursin, in JEGH. Materials and Methods: The separation was conducted on Shishedo C18 column with gradient elution of 0.1% trifluoroacetic acid–acetonitrile. Detection of wavelength was set at 205, 250, 280 and 330 nm. Results: The developed analysis showed a good linearity (R2 >0.9997). The range of limit of detection and limit of quantification were observed from 0.04 to 0.43 and from 0.11 to 1.30, respectively. The intra- and inter-day test relative standard deviations (RSD) were less than 3% and the accuracy was 95.98-108.44%. The recoveries were between 92.75% and 109.19% and RSD range of recoveries was measured from 0.52% to 2.78%. Conclusion: This HPLC-DAD method can be successfully applied for simultaneous determination of 11 major compounds in JEGH samples. PMID:24991100

HS-SPME determination of volatile carbonyl and carboxylic compounds in different matrices.

PubMed

Stashenko, Elena E; Mora, Amanda L; Cervantes, Martha E; Martínez, Jairo R

2006-07-01

Specific chromatographic methodologies are developed for the analysis of carboxylic acids (C(2)-C(6), benzoic) and aldehydes (C(2)-C(10)) of low molecular weight in diverse matrices, such as air, automotive exhaust gases, human breath, and aqueous matrices. For carboxylic acids, the method is based on their reaction with pentafluorobenzyl bromide in aqueous solution, followed by the separation and identification of the resultant pentafluorobenzyl esters by means of headspace (HS)-solid-phase microextraction (SPME) combined with gas chromatography (GC) and electron capture detection (ECD). Detection limits in the microg/m(3) range are reached, with relative standard deviation (RSD) less than 10% and linear response (R(2) > 0.99) over two orders of magnitude. The analytical methodology for aldehydes is based on SPME with simultaneous derivatization of the analytes on the fiber, by reaction with pentafluorophenylhydrazine. The derivatization reagent is previously deposited on the SPME fiber, which is then exposed to the gaseous matrix or the HS of the sample solution. The pentafluorophenyl hydrazones formed on the fiber are analyzed selectively by means of GC-ECD, with detection limits in the ng/m(3) range, RSD less than 10%, and linear response (R(2) > 0.99) over two orders of magnitude.

Study of weathering effects on the distribution of aromatic steroid hydrocarbons in crude oils and oil residues.

PubMed

Wang, Chuanyuan; Chen, Bing; Zhang, Baiyu; Guo, Ping; Zhao, Mingming

2014-01-01

The composition and distribution of triaromatic steroid hydrocarbons in oil residues after biodegradation and photo-oxidation processes were detected, and the diagnostic ratios for oil spill identification were developed and evaluated based on the relative standard deviation (RSD) and the repeatability limit. The preferential loss of C27 methyl triaromatic steranes (MTAS) relative to C28 MTAS and C29 MTAS was shown during the photo-oxidation process. In contrast to the photochemical degradation, the MTAS with the original 20R biological configuration was preferentially degraded during the biodegradation process. The RSD of most of the diagnostic ratios of MTAS ranged from 9 to 84% during the photo-oxidation process. However, the RSDs of such ratios derived from MTAS were all <5% even in high biodegradation, and such parameters may also provide new methods on oil spill identification. The parameters of monoaromatic sterane and monoaromatic sterane are not used well for oil spill identification after photo-oxidation. The triaromatic steroid hydrocarbons retained their molecular compositions after biodegradation and photo-oxidation and most of the diagnostic ratios derived from them could be efficiently used in oil spill identification.

Quantitation of Thioprolines in Grape Wine by Isotope Dilution-Liquid Chromatography-Tandem Mass Spectrometry.

PubMed

Liu, Jingjing; Meng, Xiangpeng; Chan, Wan

2016-02-17

Cysteine reacts with reactive carbonyls to form thioprolines, which have been demonstrated to possess various pharmaceutical properties. Therefore, thioproline formation is considered as a major detoxification pathway for carcinogenic reactive carbonyls. In this study, we report the initial identification of thiazolidine-4-carboxylic acid (1) and 2-methylthiazolidine-4-carboxylic acid (2), two very common thioprolines, formed by reacting formaldehyde and acetaldehyde with cysteine in grape wine samples. We have developed an isotope dilution-liquid chromatography-tandem mass spectrometry method featuring high sensitivity (limit of detection of ≤1.5 ng/mL) and selectivity to quantitate compounds 1 and 2. The method after validated to be highly accurate (recovery of ≥92%) and precise [intraday relative standard deviation (RSD) of ≤4.1% and interday RSD of ≤9.7%] was applied to determine the varying compound 1 and 2 contents in grape wine samples. Results revealed the grape type and storage duration-dependent formation of thioprolines in grape wines. Overall, the results are expected to facilitate compound-dependent investigations of the health benefits of grape wine, and our findings could be adopted to predict the age of grape wine.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patikoglou,G.; Westblade, L.; Campbell, E.

The Escherichia coli Rsd protein binds tightly and specifically to the RNA polymerase (RNAP) {sigma}{sup 70} factor. Rsd plays a role in alternative {sigma} factor-dependent transcription by biasing the competition between {sigma}{sup 70} and alternative {sigma} factors for the available core RNAP. Here, we determined the 2.6 {angstrom}-resolution X-ray crystal structure of Rsd bound to {sigma}{sup 70} domain 4 ({sigma}{sup 70}{sub 4}), the primary determinant for Rsd binding within {sigma}{sup 70}. The structure reveals that Rsd binding interferes with the two primary functions of {sigma}{sup 70}{sub 4}, core RNAP binding and promoter -35 element binding. Interestingly, the most highly conservedmore » Rsd residues form a network of interactions through the middle of the Rsd structure that connect the {sigma}{sup 70}{sub 4}-binding surface with three cavities exposed on distant surfaces of Rsd, suggesting functional coupling between {sigma}{sup 70}{sub 4} binding and other binding surfaces of Rsd, either for other proteins or for as yet unknown small molecule effectors. These results provide a structural basis for understanding the role of Rsd, as well as its ortholog, AlgQ, a positive regulator of Pseudomonas aeruginosa virulence, in transcription regulation.« less

Co-sputter deposited nickel-copper bimetallic nanoalloy embedded carbon films for electrocatalytic biomarker detection

NASA Astrophysics Data System (ADS)

Shiba, Shunsuke; Kato, Dai; Kamata, Tomoyuki; Niwa, Osamu

2016-06-01

We report the fabrication of a nickel (Ni)-copper (Cu) bimetallic nanoalloy (~3 nm) embedded carbon film electrode with the unbalanced magnetron (UBM) co-sputtering technique, which requires only a one-step process at room temperature. Most of each nanoalloy body was firmly embedded in a chemically stable carbon matrix with an atomically flat surface (Ra: 0.21 nm), suppressing the aggregation and/or detachment of the nanoalloy from the electrode surface. The nanoalloy size and composition can be controlled simply by individually controlling the target powers of carbon, Ni and Cu, which also makes it possible to localize the nanoalloys near the electrode surface. This electrode exhibited excellent electrocatalytic activity for d-mannitol, which should be detected with a low detection limit in urine samples for the diagnosis of severe intestinal diseases. With a Ni/Cu ratio of around 64/36, the electrocatalytic current per metal area was 3.4 times larger than that of an alloy film electrode with a similar composition (~70/30). This improved electrocatalytic activity realized higher stability (n = 60, relative standard deviation (RSD): 4.6%) than the alloy film (RSD: 32.2%) as demonstrated by continuous measurements of d-mannitol.We report the fabrication of a nickel (Ni)-copper (Cu) bimetallic nanoalloy (~3 nm) embedded carbon film electrode with the unbalanced magnetron (UBM) co-sputtering technique, which requires only a one-step process at room temperature. Most of each nanoalloy body was firmly embedded in a chemically stable carbon matrix with an atomically flat surface (Ra: 0.21 nm), suppressing the aggregation and/or detachment of the nanoalloy from the electrode surface. The nanoalloy size and composition can be controlled simply by individually controlling the target powers of carbon, Ni and Cu, which also makes it possible to localize the nanoalloys near the electrode surface. This electrode exhibited excellent electrocatalytic activity for d-mannitol, which should be detected with a low detection limit in urine samples for the diagnosis of severe intestinal diseases. With a Ni/Cu ratio of around 64/36, the electrocatalytic current per metal area was 3.4 times larger than that of an alloy film electrode with a similar composition (~70/30). This improved electrocatalytic activity realized higher stability (n = 60, relative standard deviation (RSD): 4.6%) than the alloy film (RSD: 32.2%) as demonstrated by continuous measurements of d-mannitol. Electronic supplementary information (ESI) available: The concept of UBM co-sputtering for fabricating nanoalloy embedded carbon films. HRTEM images of the NiNP and Ni32Cu68 nanoalloy embedded carbon films. The experimental conditions for sputter deposition, HRTEM, HAADF-STEM, STEM-EDS measurements and continuous flow injection analysis. XPS analysis of the nanoalloy embedded carbon film. Repeated CVs of both the nanoalloy embedded carbon film and the alloy film. Amperometric detection of d-mannitol in the presence of chloride ions. See DOI: 10.1039/c6nr02287a

Determination of Oversulphated Chondroitin Sulphate and Dermatan Sulphate in unfractionated heparin by (1)H-NMR - Collaborative study for quantification and analytical determination of LoD.

PubMed

McEwen, I; Mulloy, B; Hellwig, E; Kozerski, L; Beyer, T; Holzgrabe, U; Wanko, R; Spieser, J-M; Rodomonte, A

2008-12-01

Oversulphated Chondroitin Sulphate (OSCS) and Dermatan Sulphate (DS) in unfractionated heparins can be identified by nuclear magnetic resonance spectrometry (NMR). The limit of detection (LoD) of OSCS is 0.1% relative to the heparin content. This LoD is obtained at a signal-to-noise ratio (S/N) of 2000:1 of the heparin methyl signal. Quantification is best obtained by comparing peak heights of the OSCS and heparin methyl signals. Reproducibility of less than 10% relative standard deviation (RSD) has been obtained. The accuracy of quantification was good.

Determination of the Cryolite Ratio of KF-NaF-AlF3 Electrolyte by Conductivity Method

NASA Astrophysics Data System (ADS)

Yan, Hengwei; Yang, Jianhong; Liu, Zhanwei; Wang, Chengzhi; Ma, Wenhui

2018-05-01

The cryolite ratio (CR) is an important parameter for the electrolyte in aluminum reduction cells. The measurement method for the CR of the KF-NaF-AlF3 system acid (CR < 3) electrolyte by means of electrical conductivity was initially developed, and the formula for calculating the CR was deduced. This method has the advantages of simple operation and high precision. In addition, the relative standard deviations (RSD) of the measurement are < 1.2 pct, and the analysis error of the NaF or KF content has little effect on the determination of the CR.

Inclusion of 1-naphthylacetic acid and 2-(1-naphthyl)acetamide into three typical multiresidue methods for LC/MS/MS analysis of tomatoes and zucchini.

PubMed

Lozano, Ana; Pérez-Parada, Andrés; Heinzen, Horacio; Fernández-Alba, Amadeo R

2012-01-01

In spite of high plant growth regulator application rates, little has been reported in the literature on determination of their residues in fruits and vegetables. This would be useful in monitoring good manufacturing practices and overall safety through the enforcement of maximum residue levels (MRLs). The present work describes method validation for the determination of 1-naphthylacetic acid (NAA) and 2(1-naphthyl)acetamide (NAAm) in tomato and zucchini using the mini-Luke, ethyl acetate (EtOAc) and acetate-buffered quick, easy, cheap, effective, rugged, and safe (QuEChERS) methods. Samples were spiked at two different levels: 50 and 100 pg/kg for NAA and 20 and 100 pg/kg for NAAm. These compounds were analyzed within the same chromatographic run with LC coupled to triple quadrupole MS (LC/(QqQ)MS/MS) in positive and negative electrospray ionization [ESI(+) and ESI(-)] modes for NAAm and NAA, respectively. For analyte confirmation, LC/ESI(-)QTOF-MS was also investigated given that NAA has only one multiple reaction monitoring transition (185.1-*140.9 m/z). These three common methods were used to determine linearity, recoveries, precision (RSD), matrix effects, repeatability, and reproducibility (n = 5) for the selected matrixes. In terms of the Directorate-General for Health and Consumers (DG-SANCO) guidelines, only insignificant differences were found for the multiresidue methods tested, regardless of the commodity. Matrix-matched calibration was used, and LODs were below 10.1 pg/kg for NAA and 6.0 pg/kg for NAAm, which were lower than the MRLs established in current European Union legislation for these compounds. Obtained recoveries for NAA ranged from 87 to 107% with RSD values below 10% for mini-Luke, 83 to 107% with RSD <11% for EtOAc, and 76 to 85% with RSD <7% for QuEChERS. NAAm recoveries ranged from 74 to 102% with RSD 5 15% for mini-Luke, 76 to 97% with RSD <4% for EtOAc, and 76 to 93% with RSD < 5% for QuEChERS. The linearity of the response over two orders of magnitude was demonstrated (r2 > 0.996) for all methods used. Good repeatability and reproducibility in terms of RSD were obtained (11.3-17.8%) for these analytical methods. The results were acceptable within the studied ranges for both analytes in all methods. As these multiresidue methods are used at the present time in many laboratories, this survey indicates that these analytes should be included in their monitoring scope.

UFLC-ESI-MS/MS analysis of multiple mycotoxins in medicinal and edible Areca catechu.

PubMed

Liu, Hongmei; Luo, Jiaoyang; Kong, Weijun; Liu, Qiutao; Hu, Yichen; Yang, Meihua

2016-05-01

A robust, sensitive and reliable ultra fast liquid chromatography combined with electrospray ionization tandem mass spectrometry (UFLC-ESI-MS/MS) was optimized and validated for simultaneous identification and quantification of eleven mycotoxins in medicinal and edible Areca catechu, based on one-step extraction without any further clean-up. Separation and quantification were performed in both positive and negative modes under multiple reaction monitoring (MRM) in a single run with zearalanone (ZAN) as internal standard. The chromatographic conditions and MS/MS parameters were carefully optimized. Matrix-matched calibration was recommended to reduce matrix effects and improve accuracy, showing good linearity within wide concentration ranges. Limits of quantification (LOQ) were lower than 50 μg kg(-1), while limits of detection (LOD) were in the range of 0.1-20 μg kg(-1). The accuracy of the developed method was validated for recoveries, ranging from 85% to 115% with relative standard deviation (RSD) ≤14.87% at low level, from 75% to 119% with RSD ≤ 14.43% at medium level and from 61% to 120% with RSD ≤ 13.18% at high level, respectively. Finally, the developed multi-mycotoxin method was applied for screening of these mycotoxins in 24 commercial samples. Only aflatoxin B2 and zearalenone were found in 2 samples. This is the first report on the application of UFLC-ESI(+/-)-MS/MS for multi-class mycotoxins in A. catechu. The developed method with many advantages of simple pretreatment, rapid determination and high sensitivity is a proposed candidate for large-scale detection and quantification of multiple mycotoxins in other complex matrixes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Protocol proposal for, and evaluation of, consistency in nicotine delivery from the liquid to the aerosol of electronic cigarettes atomizers: regulatory implications.

PubMed

Farsalinos, Konstantinos E; Yannovits, Nikoletta; Sarri, Theoni; Voudris, Vassilis; Poulas, Konstantinos

2016-06-01

To propose a protocol and evaluate the consistency in nicotine delivery to the aerosol of different types of electronic cigarette (EC) atomizers, as required by regulatory authorities. Three cartomizer and four tank-type atomizer products were tested (three samples per product). The aerosol from three 20-puff sessions from each sample was collected using a smoke machine. Three cartridges from a nicotine inhaler and three tobacco cigarettes were also tested. Analytical laboratory in Greece. Aerosol nicotine levels were measured. Relative standard deviation (RSD, i.e. coefficient of variation) was calculated separately for each cartomizer and replacement atomizer head sample (intrasample RSD) and between different samples (intersample RSD). The percentage difference from the mean, which is used to assess the quality of medicinal nebulizers, was also calculated. The aerosol nicotine levels were 1.01-10.61 mg/20 puffs for ECs, 0.12-0.18 mg/20 puffs for the nicotine inhaler and 1.76-2.20 mg/cigarette for the tobacco cigarettes. The intrasample RSDs were 3.7-12.5% for ECs and 14.3% for the nicotine inhaler and 11.1% for the tobacco cigarettes. The intersample RSDs were higher in cartomizers (range: 6.9-37.8%) compared with tank systems (range: 6.4-9.3%). All tank-type atomizers and one cartomizer were within 75-125% of the mean, as dictated for medicinal nebulizers. Electronic cigarettes that use tank-type atomizers appear to deliver nicotine in more consistent quantities (within the acceptable limits for medicinal nebulizers and similar to the nicotine inhaler) than electronic cigarettes that use cartomizers. The protocol for testing nicotine delivery consistency described in this paper could be used effectively for regulatory purposes. © 2016 Society for the Study of Addiction.

Precise and accurate isotope ratio measurements by ICP-MS.

PubMed

Becker, J S; Dietze, H J

2000-09-01

The precise and accurate determination of isotope ratios by inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS (LA-ICP-MS) is important for quite different application fields (e.g. for isotope ratio measurements of stable isotopes in nature, especially for the investigation of isotope variation in nature or age dating, for determining isotope ratios of radiogenic elements in the nuclear industry, quality assurance of fuel material, for reprocessing plants, nuclear material accounting and radioactive waste control, for tracer experiments using stable isotopes or long-lived radionuclides in biological or medical studies). Thermal ionization mass spectrometry (TIMS), which used to be the dominant analytical technique for precise isotope ratio measurements, is being increasingly replaced for isotope ratio measurements by ICP-MS due to its excellent sensitivity, precision and good accuracy. Instrumental progress in ICP-MS was achieved by the introduction of the collision cell interface in order to dissociate many disturbing argon-based molecular ions, thermalize the ions and neutralize the disturbing argon ions of plasma gas (Ar+). The application of the collision cell in ICP-QMS results in a higher ion transmission, improved sensitivity and better precision of isotope ratio measurements compared to quadrupole ICP-MS without the collision cell [e.g., for 235U/238U approximately 1 (10 microg x L(-1) uranium) 0.07% relative standard deviation (RSD) vs. 0.2% RSD in short-term measurements (n = 5)]. A significant instrumental improvement for ICP-MS is the multicollector device (MC-ICP-MS) in order to obtain a better precision of isotope ratio measurements (with a precision of up to 0.002%, RSD). CE- and HPLC-ICP-MS are used for the separation of isobaric interferences of long-lived radionuclides and stable isotopes by determination of spallation nuclide abundances in an irradiated tantalum target.

Preparation and utilization of molecularly imprinted polymer for chlorsulfuron extraction from water, soil, and wheat plant.

PubMed

Fu, Xu Wei; Wu, Yan Jiao; Qu, Jin Rong; Yang, Hong

2012-07-01

A molecularly imprinted polymer (MIP) was prepared using chlorsulfuron (CS), a herbicide as a template molecule, methacrylic acid as a functional monomer, ethylene glycol dimethacrylate (EDMA) as a cross-linker, methanol and toluene as a porogen, and 2,2-azobisisobutyronitrile as an initiator. The binding behaviors of the template chlorsulfuron and its analog on MIP were evaluated by equilibrium adsorption experiments, which showed that the MIP particles had specific affinity for the template CS. Solid-phase extraction (SPE) with the chlorsulfuron molecularly imprinted polymer as an adsorbent was investigated. The optimum loading, washing, and eluting conditions for chlorsulfuron molecularly imprinted polymer solid-phase extraction (CS-MISPE) were established. The optimized CS-MISPE procedure was developed to enrich and clean up the chlorsulfuron residue in water, soils, and wheat plants. Concentrations of chlorsulfuron in the samples were analyzed by HPLC-UVD. The average recoveries of CS spiked standard at 0.05~0.2 mg L(-1) in water were 90.2~93.3%, with the relative standard deviation (RSD) being 2.0~3.9% (n=3). The average recoveries of 1.0 mL CS spiked standard at 0.1~0.5 mg L(-1) in 10 g soil were 91.1~94.7%, with the RSD being 3.1~5.6% (n=3). The average recoveries of 1.0 mL CS spiked standard at 0.1~0.5 mg L(-1) in 5 g wheat plant were 82.3~94.3%, with the RSD being 2.9~6.8% (n=3). Overall, our study provides a sensitive and cost-effective method for accurate determination of CS residues in water, soils, and plants.

Development of a comprehensive screening method for more than 300 organic chemicals in water samples using a combination of solid-phase extraction and liquid chromatography-time-of-flight-mass spectrometry.

PubMed

Chau, Hong Thi Cam; Kadokami, Kiwao; Ifuku, Tomomi; Yoshida, Yusuke

2017-12-01

A comprehensive screening method for 311 organic compounds with a wide range of physicochemical properties (log Pow -2.2-8.53) in water samples was developed by combining solid-phase extraction with liquid chromatography-high-resolution time-of-flight mass spectrometry. Method optimization using 128 pesticides revealed that tandem extraction with styrene-divinylbenzene polymer and activated carbon solid-phase extraction cartridges at pH 7.0 was optimal. The developed screening method was able to extract 190 model compounds with average recovery of 80.8% and average relative standard deviations (RSD) of 13.5% from spiked reagent water at 0.20 μg L -1 , and 87.1% recovery and 10.8% RSD at 0.05 μg L -1 . Spike-recovery testing (0.20 μg L -1 ) using real sewage treatment plant effluents resulted in an average recovery and average RSD of 190 model compounds of 77.4 and 13.1%, respectively. The method was applied to the influent and effluent of five sewage treatment plants in Kitakyushu, Japan, with 29 out of 311 analytes being observed at least once. The results showed that this method can screen for a large number of chemicals with a wide range of physicochemical properties quickly and at low operational cost, something that is difficult to achieve using conventional analytical methods. This method will find utility in target screening of hazardous chemicals with a high risk in environmental waters, and for confirming the safety of water after environmental incidents.

Determination of aliskiren in tablet dosage forms by a validated stability-indicating RP-LC method.

PubMed

Wrasse-Sangoi, M; Sangoi, M S; Oliveira, P R; Secretti, L T; Rolim, C M B

2011-02-01

A reversed-phase liquid chromatography (RP-LC) method is validated for the determination of aliskiren in tablet dosage form. The LC method is carried out on a Waters XBridge C(18) column (150 × 4.6 mm i.d.), maintained at 25°C. The mobile phase consisted of acetonitrile:water (95:5, v/v)/phosphoric acid (25 mM, pH 3.0) (40:60, v/v), run at a flow rate of 1.0 mL/min, with photodiode array detector set at 229 nm. The chromatographic separation is obtained with aliskiren retention time of 3.68 min, and it is linear in the range of 10-300 μg/mL (r = 0.9999). The limits of detection and quantitation are 2.38 and 7.93 μg/mL, respectively. The specificity and stability-indicating capability of the method are proven through degradation studies, which also showed that there is no interference of the formulation excipients, showing that peak is free from any coeluting peak. The method showed adequate precision, with a relative standard deviation (RSD) values lower than 0.92%. Good values of accuracy were also obtained, with a mean value of 99.55%. Experimental design is used during validation to calculate method robustness. The proposed method is applied for the analysis of the tablet dosage forms, contributing to improve the quality control and to assure the therapeutic efficacy.

Inflammatory Bowel Diseases (Crohn´s Disease and Ulcerative Colitis): Cost of Treatment in Serbia and the Implications.

PubMed

Kostić, Marina; Djakovic, Ljiljan; Šujić, Raša; Godman, Brian; Janković, Slobodan M

2017-02-01

Although the costs of treating inflammatory bowel disease (IBD) in developed countries are well established, they remain largely unknown in countries with recent histories of socio-economic transition including Serbia. To estimate the costs of treatment including the resources used by patients with IBD in Serbia from a societal perspective. This includes both Crohn's disease and ulcerative colitis. This cost-of-illness study was conducted to identify direct, indirect and out-of-pocket costs of treating patients with IBD in Serbia. Patients with IBD (n = 112) completed a semi-structured questionnaire with data concerning their utilisation of heath-care resources and illness-related expenditures. All costs were calculated in Republic of Serbia dinars (RSD) at a 1-year level (2014) and subsequently converted to Euros. Median values and ranges were reported to avoid potential distortions associated with mean costs. Median total direct costs and total indirect costs per patient per year in patients with Crohn's disease were 192,614.32RSD (€1602.97) and 28,014.00RSD (€233.13) and 142,267.15RSD (€1183.97) and 21,436.00RSD (€178.39), respectively, in patients with ulcerative colitis. In both groups, the greatest component of direct costs was hospitalisation. Costs of IBD in Serbia are lower than in more developed countries for two reasons. These include the fact that expensive biological therapy is currently under-utilised in Serbia and prices of health services are largely controlled by the State at a low level. The under-utilisation of biologicals may change with the advent of biosimilars at increasingly lower prices.

A study on raindrop size distribution variability in before and after landfall precipitations of tropical cyclones observed over southern India

NASA Astrophysics Data System (ADS)

Janapati, Jayalakshmi; seela, Balaji Kumar; Reddy M., Venkatrami; Reddy K., Krishna; Lin, Pay-Liam; Rao T., Narayana; Liu, Chian-Yi

2017-06-01

Raindrop size distribution (RSD) characteristics in before landfall (BLF) and after landfall (ALF) of three tropical cyclones (JAL, THANE, and NILAM) induced precipitations are investigated by using a laser-based (PARticleSIze and VELocity - PARSIVEL) disdrometer at two different locations [Kadapa (14.47°N, 78.82°E) and Gadanki (13.5°N, 79.2°E)] in semi-arid region of southern India. In both BLF and ALF precipitations of these three cyclones, convective precipitations have higher mass weighted mean diameter (Dm) and lower normalized intercept parameter (log10Nw) values than stratiform precipitations. The radar reflectivity (Z) and rain rate (R) relations (Z=A*Rb) showed distinct variations in BLF and ALF precipitations of three cyclones. BLF precipitation of JAL cyclone has a higher Dm than ALF precipitation. Whereas, for THANE and NILAM cyclones ALF precipitations have higher Dm than BLF. The Dm values of three cyclones (both in BLF and ALF) are smaller than the Dm values of the other (Atlantic and Pacific) oceanic cyclones. Interaction of different regions (eyewall, inner rainbands, and outer rainbands) of cyclones with the environment and underlying surface led to RSD variations between BLF and ALF precipitations through different microphysical (collision-coalescence, breakup, evaporation, and riming) processes. The immediate significance of the present work is that (i) it contributes to our understanding of cyclone RSD in BLF and ALF precipitations, and (ii) it provides the useful information for quantitative estimation of rainfall from Doppler weather radar observations.

Transcriptional organization and in vivo role of the Escherichia coli rsd gene, encoding the regulator of RNA polymerase sigma D.

PubMed

Jishage, M; Ishihama, A

1999-06-01

The regulator of sigma D (Rsd) was identified as an RNA polymerase sigma70-associated protein in stationary-phase Escherichia coli with the inhibitory activity of sigma70-dependent transcription in vitro (M. Jishage and A. Ishihama, Proc. Natl. Acad. Sci. USA 95:4953-4958, 1998). Primer extension analysis of rsd mRNA indicated the presence of two promoters, sigmaS-dependent P1 and sigma70-dependent P2 with the gearbox sequence. To get insight into the in vivo role of Rsd, the expression of a reporter gene fused to either the sigma70- or sigmaS-dependent promoter was analyzed in the absence of Rsd or the presence of overexpressed Rsd. In the rsd null mutant, the sigma70- and sigmaS-dependent gene expression was increased or decreased, respectively. On the other hand, the sigma70- or sigmaS-dependent transcription was reduced or enhanced, respectively, after overexpression of Rsd. The repression of the sigmaS-dependent transcription in the rsd mutant is overcome by increased production of the sigmaS subunit. Together these observations support the prediction that Rsd is involved in replacement of the RNA polymerase sigma subunit from sigma70 to sigmaS during the transition from exponential growth to the stationary phase.

Changes in the soil microbial community after reductive soil disinfestation and cucumber seedling cultivation.

PubMed

Huang, Xinqi; Liu, Liangliang; Wen, Teng; Zhang, Jinbo; Wang, Fenghe; Cai, Zucong

2016-06-01

Reductive soil disinfestation (RSD) has been proven to be an effective and environmentally friendly way to control many soilborne pathogens and diseases. In this study, the RSDs using ethanol (Et-RSD) and alfalfa (Al-RSD) as organic carbons were performed in a Rhizoctonia solani-infected soil, and the dissimilarities of microbial communities during the RSDs and after planting two seasons of cucumber seedlings in the RSDs-treated soil were respectively investigated by MiSeq pyrosequencing. The results showed that, as for bacteria, Coprococcus, Flavisolibacter, Rhodanobacter, Symbiobacterium, and UC-Ruminococcaceae became the dominant bacterial genera at the end of Al-RSD. In contrast, Et-RSD soil involved more bacteria belonging to Firmicutes, such as Sedimentibacter, UC-Gracilibacteraceae, and Desulfosporosinus. For fungi, Chaetomium significantly increased at the end of RSDs, while Rhizoctonia and Aspergillus significantly decreased. After planting two seasons of cucumber seedlings, those bacteria belonging to Firmicutes significantly decreased, but Lysobacter and Rhodanobacter belonging to the phylum Proteobacteria as well as UC-Sordariales and Humicola belonging to Ascomycota alternatively increased in Al- and Et-RSD-treated soils. Besides, some nitrification, denitrification, and nitrogen fixation genes were apparently increased in the RSD-treated soils, but the effect was more profound in Al-RSD than Et-RSD. Overall, Et-RSD could induced more antagonists belonging to Firmicutes under anaerobic condition, whereas Al-RSD could continuously stimulate some functional microorganisms (Lysobacter and Rhodanobacter) and further improve nitrogen transformation activities in the soil at the coming cropping season.

The Escherichia coli regulator of sigma 70 protein, Rsd, can up-regulate some stress-dependent promoters by sequestering sigma 70.

PubMed

Mitchell, Jennie E; Oshima, Taku; Piper, Sarah E; Webster, Christine L; Westblade, Lars F; Karimova, Gouzel; Ladant, Daniel; Kolb, Annie; Hobman, Jon L; Busby, Stephen J W; Lee, David J

2007-05-01

The Escherichia coli Rsd protein forms complexes with the RNA polymerase sigma(70) factor, but its biological role is not understood. Transcriptome analysis shows that overexpression of Rsd causes increased expression from some promoters whose expression depends on the alternative sigma(38) factor, and this was confirmed by experiments with lac fusions at selected promoters. The LP18 substitution in Rsd increases the Rsd-dependent stimulation of these promoter-lac fusions. Analysis with a bacterial two-hybrid system shows that the LP18 substitution in Rsd increases its interaction with sigma(70). Our experiments support a model in which the role of Rsd is primarily to sequester sigma(70), thereby increasing the levels of RNA polymerase containing the alternative sigma(38) factor.

The E. coli Anti-Sigma Factor Rsd: Studies on the Specificity and Regulation of Its Expression

PubMed Central

Hofmann, Nina; Wurm, Reinhild; Wagner, Rolf

2011-01-01

Background Among the seven different sigma factors in E. coli σ70 has the highest concentration and affinity for the core RNA polymerase. The E. coli protein Rsd is regarded as an anti-sigma factor, inhibiting σ70-dependent transcription at the onset of stationary growth. Although binding of Rsd to σ70 has been shown and numerous structural studies on Rsd have been performed the detailed mechanism of action is still unknown. Methodology/Principal Findings We have performed studies to unravel the function and regulation of Rsd expression in vitro and in vivo. Cross-linking and affinity binding revealed that Rsd is able to interact with σ70, with the core enzyme of RNA polymerase and is able to form dimers in solution. Unexpectedly, we find that Rsd does also interact with σ38, the stationary phase-specific sigma factor. This interaction was further corroborated by gel retardation and footprinting studies with different promoter fragments and σ38- or σ70-containing RNA polymerase in presence of Rsd. Under competitive in vitro transcription conditions, in presence of both sigma factors, a selective inhibition of σ70-dependent transcription was prevailing, however. Analysis of rsd expression revealed that the nucleoid-associated proteins H-NS and FIS, StpA and LRP bind to the regulatory region of the rsd promoters. Furthermore, the major promoter P2 was shown to be down-regulated in vivo by RpoS, the stationary phase-specific sigma factor and the transcription factor DksA, while induction of the stringent control enhanced rsd promoter activity. Most notably, the dam-dependent methylation of a cluster of GATC sites turned out to be important for efficient rsd transcription. Conclusions/Significance The results contribute to a better understanding of the intricate mechanism of Rsd-mediated sigma factor specificity changes during stationary phase. PMID:21573101

The E. coli anti-sigma factor Rsd: studies on the specificity and regulation of its expression.

PubMed

Hofmann, Nina; Wurm, Reinhild; Wagner, Rolf

2011-05-06

Among the seven different sigma factors in E. coli σ(70) has the highest concentration and affinity for the core RNA polymerase. The E. coli protein Rsd is regarded as an anti-sigma factor, inhibiting σ(70)-dependent transcription at the onset of stationary growth. Although binding of Rsd to σ(70) has been shown and numerous structural studies on Rsd have been performed the detailed mechanism of action is still unknown. We have performed studies to unravel the function and regulation of Rsd expression in vitro and in vivo. Cross-linking and affinity binding revealed that Rsd is able to interact with σ(70), with the core enzyme of RNA polymerase and is able to form dimers in solution. Unexpectedly, we find that Rsd does also interact with σ(38), the stationary phase-specific sigma factor. This interaction was further corroborated by gel retardation and footprinting studies with different promoter fragments and σ(38)- or σ(70)-containing RNA polymerase in presence of Rsd. Under competitive in vitro transcription conditions, in presence of both sigma factors, a selective inhibition of σ(70)-dependent transcription was prevailing, however. Analysis of rsd expression revealed that the nucleoid-associated proteins H-NS and FIS, StpA and LRP bind to the regulatory region of the rsd promoters. Furthermore, the major promoter P2 was shown to be down-regulated in vivo by RpoS, the stationary phase-specific sigma factor and the transcription factor DksA, while induction of the stringent control enhanced rsd promoter activity. Most notably, the dam-dependent methylation of a cluster of GATC sites turned out to be important for efficient rsd transcription. The results contribute to a better understanding of the intricate mechanism of Rsd-mediated sigma factor specificity changes during stationary phase.

Repeated social defeat-induced neuroinflammation, anxiety-like behavior and resistance to fear extinction were attenuated by the cannabinoid receptor agonist WIN55,212-2.

PubMed

Lisboa, Sabrina Francesca; Niraula, Anzela; Resstel, Leonardo Barbosa; Guimaraes, Francisco Silveira; Godbout, Jonathan P; Sheridan, John F

2018-04-17

Psychosocial stress contributes to the development of psychiatric disorders. Repeated social defeat (RSD) is a murine stressor that causes a release of inflammatory monocytes into circulation. Moreover, RSD-induced anxiety-like behavior is dependent on the recruitment of these monocytes to the brain. Activation of the endocannabinoid (ECB) system may modulate both neuroendocrine and inflammatory responses mediated by stress. Therefore, we hypothesized that a cannabinoid receptor agonist would attenuate RSD-induced inflammation, anxiety, and stress sensitization. To test this hypothesis, mice received an injection of the synthetic cannabinoid 1/2 receptor agonist, WIN55,212-2 (WIN; 1 mg/kg, intraperitoneally) daily for six consecutive days, 30 min before each exposure to RSD. Anxiety-like behavior, immune activation, neuroinflammation, and microglial reactivity were determined 14 h after RSD. RSD-induced anxiety-like behavior in the open field and in the EPM was reversed by WIN55,212-2. Moreover, WIN55,212-2 reduced the accumulation of inflammatory monocytes in circulation and brain after RSD and attenuated RSD-induced interleukin-1β (IL-1β) messenger RNA (mRNA) expression in microglia/macrophages. Increased ex vivo reactivity of microglia/monocytes to lipopolysaccharides (LPS) after RSD was also attenuated by WIN55,212-2. Next, fear expression, extinction, and recall were evaluated 24 and 48 h, respectively, after contextual fear conditioning, which took place 7 days after RSD. Here, RSD caused prolonged fear expression and impaired fear extinction recall, which was associated with increased IL-1β mRNA in the brain. Moreover, these stress-induced effects were reversed by WIN55,212-2. In conclusion, activation of cannabinoid receptors limited the immune and neuroinflammatory responses to RSD and reversed the short-term and long-term behavioral deficits associated with RSD.

Design of ultraviolet wavelength and standard solution concentrations in relative response factors for simultaneous determination of multi-components with single reference standard in herbal medicines.

PubMed

Yang, Ting-Wen; Zhao, Chao; Fan, Yong; Qi, Lian-Wen; Li, Ping

2015-10-10

Single standard to determine multi-components (SSDMC) is a practical pattern for quality evaluation of herbal medicines (HMs). However, it remains challenging because of potential inconsistency of relative response factors (RRF) on different instruments. In this work, the effects of two key roles, i.e., ultraviolet (UV) wavelength and standard solution concentrations, on reproducibility of RRF were investigated. The effect of UV wavelength on reproducibility of RRF was studied by plotting the relationship of the peak area ratios (internal standard vs analyte) to wavelengths. The preferable wavelength should be set at the flat parts of the curve. Optimized 300 nm produced a 0.38% RSD for emodin/emodin-8-O-β-D-glucopyranoside on five instruments, much lower than 2.80% obtained from the maximum wavelength at 290 nm. Next, the effects of standard solution concentrations of emodin on its response factor (RF) were investigated. For one single point method, low concentration less than 49 b/k resulted in significant variations in RF. For emodin, when the concentration is higher than 7.00 μg mL(-1), a low standard deviation (SD) value at 0.13 was obtained, while lower than 7.00 μg mL(-1), a high SD at 3.71 was obtained. The developed SSDMC method was then applied to determination of target components in 10 Polygonum cuspidatum samples and showed comparable accuracy to conventional calibration methods with deviation less than 1%. Copyright © 2015 Elsevier B.V. All rights reserved.

Analysis of L-citrulline and L-arginine in Ficus deltoidea leaf extracts by reverse phase high performance liquid chromatography

PubMed Central

Shafaei, Armaghan; Aisha, Abdalrahim F. A.; Siddiqui, Mohammad Jamshed Ahmad; Ismail, Zhari

2015-01-01

Background: Ficus deltoidea (FD) is one of the native plants widely distributed in several countries in Southeast Asia. Previous studies have shown that FD leaf possess antinociceptive, wound healing and antioxidant properties. These beneficial effects have been attributed to the presence of primary and secondary metabolites such as polyphenols, amino acids and flavonoids. Objective: The aim was to develop a reverse phase high-performance liquid chromatography method with ultraviolet detection that involves precolumn derivatisation with O-phthaladehyde for simultaneous analysis of two amino acids L-citrulline and L-arginine in FD leaf extracts. Materials and Methods: An isocratic elution program consisting of methanol: acetonitrile: Water at 45:45:10 v/v (solvent A) and 0.1 M phosphate buffer pH 7.5 (solvent B) at A: B v/v ratio of 80:20 on Zorbax Eclipse C18 SB-Aq column (250 × 4.6 mm, 5 μm) were used. The flow rate was set at 1 ml/min and detection was carried out at 338 nm with 30 min separation time. Results: Good linearity for L-citrulline and L-arginine was obtained in the range 0.1-1000 μg/ml at R2 ≥ 0.998. The limit of detection and limit of quantification values for both L-citrulline and L-arginine were 1 and 5 μg/ml, respectively. The average of recoveries was in the range 94.94-101.95%, with relative standard deviation (%RSD) less than 3%. Intra- and inter-day precision was in the range 96.36-102.43% with RSD less than 2%. Conclusion: All validation parameters of the developed method indicate the method is reliable and efficient for simultaneous determination of L-citrulline and L-arginine for routine analysis of FD. PMID:25598632

The performance and the characterization of laser ablation aerosol particle time-of-flight mass spectrometry (LAAP-ToF-MS)

NASA Astrophysics Data System (ADS)

Gemayel, Rachel; Hellebust, Stig; Temime-Roussel, Brice; Hayeck, Nathalie; Van Elteren, Johannes T.; Wortham, Henri; Gligorovski, Sasho

2016-05-01

Hyphenated laser ablation-mass spectrometry instruments have been recognized as useful analytical tools for the detection and chemical characterization of aerosol particles. Here we describe the performances of a laser ablation aerosol particle time-of-flight mass spectrometer (LAAP-ToF-MS) which was designed for aerodynamic particle sizing using two 405 nm scattering lasers and characterization of the chemical composition of single aerosol particle via ablation/ionization by a 193 nm excimer laser and detection in a bipolar time-of-flight mass spectrometer with a mass resolving power of m/Δm > 600.

We describe a laboratory based optimization strategy for the development of an analytical methodology for characterization of atmospheric particles using the LAAP-ToF-MS instrument in combination with a particle generator, a differential mobility analyzer and an optical particle counter. We investigated the influence of particle number concentration, particle size and particle composition on the detection efficiency. The detection efficiency is a product of the scattering efficiency of the laser diodes and the ionization efficiency or hit rate of the excimer laser. The scattering efficiency was found to vary between 0.6 and 1.9 % with an average of 1.1 %; the relative standard deviation (RSD) was 17.0 %. The hit rate exhibited good repeatability with an average value of 63 % and an RSD of 18 %. In addition to laboratory tests, the LAAP-ToF-MS was used to sample ambient air during a period of 6 days at the campus of Aix-Marseille University, situated in the city center of Marseille, France. The optimized LAAP-ToF-MS methodology enables high temporal resolution measurements of the chemical composition of ambient particles, provides new insights into environmental science, and a new investigative tool for atmospheric chemistry and physics, aerosol science and health impact studies.

Tantala-based sol-gel coating for capillary microextraction on-line coupled to high-performance liquid chromatography.

PubMed

Tran, MinhPhuong; Turner, Erica B; Segro, Scott S; Fang, Li; Seyyal, Emre; Malik, Abdul

2017-11-03

A sol-gel organic-inorganic hybrid sorbent, consisting of chemically integrated tantalum (V) ethoxide (TaEO) and polypropylene glycol methacrylate (PPGM), was developed for capillary microextraction (CME). The sol-gel sorbent was synthesized within a fused silica capillary through hydrolytic polycondensation of TaEO and chemical incorporation of PPGM into the evolving sol-gel tantala network. A part of the organic-inorganic hybrid sol-gel network evolving in the vicinity of the capillary walls had favorable conditions to get chemically bonded to the silanol groups on the capillary surface forming a surface-bonded coating. The newly developed sol-gel sorbent was employed to isolate and enrich a variety of analytes from aqueous samples for on-line analysis by high-performance liquid chromatography (HPLC) equipped with a UV detector. CME was performed on aqueous samples containing trace concentrations of analytes representing polycyclic aromatic hydrocarbons, ketones, alcohols, amines, nucleosides, and nucleotides. This sol-gel hybrid coating provided efficient extraction with CME-HPLC detection limits ranging from 4.41pM to 28.19 pM. Due to direct chemical bonding between the sol-gel sorbent coating and the fused silica capillary inner surface, this sol-gel sorbent exhibited enhanced solvent stability. The sol-gel tantala-based sorbent also exhibited excellent pH stability over a wide pH range (pH 0-pH 14). Furthermore, it displayed great performance reproducibility in CME-HPLC providing run-to-run HPLC peak area relative standard deviation (RSD) values between 0.23% and 3.83%. The capillary-to-capillary RSD (n=3), characterizing capillary preparation method reproducibility, ranged from 0.24% to 4.11%. The results show great performance consistency and application potential for the sol-gel tantala-PPGM sorbent in various fields including biomedical, pharmaceutical, and environmental areas. Copyright © 2017 Elsevier B.V. All rights reserved.

Identification of homemade inorganic explosives by ion chromatographic analysis of post-blast residues.

PubMed

Johns, Cameron; Shellie, Robert A; Potter, Oscar G; O'Reilly, John W; Hutchinson, Joseph P; Guijt, Rosanne M; Breadmore, Michael C; Hilder, Emily F; Dicinoski, Greg W; Haddad, Paul R

2008-02-29

Anions and cations of interest for the post-blast identification of homemade inorganic explosives were separated and detected by ion chromatographic (IC) methods. The ionic analytes used for identification of explosives in this study comprised 18 anions (acetate, benzoate, bromate, carbonate, chlorate, chloride, chlorite, chromate, cyanate, fluoride, formate, nitrate, nitrite, perchlorate, phosphate, sulfate, thiocyanate and thiosulfate) and 12 cations (ammonium, barium(II), calcium(II), chromium(III), ethylammonium, magnesium(II), manganese(II), methylammonium, potassium(I), sodium(I), strontium(II), and zinc(II)). Two IC separations are presented, using suppressed IC on a Dionex AS20 column with potassium hydroxide as eluent for anions, and non-suppressed IC for cations using a Dionex SCS 1 column with oxalic acid/acetonitrile as eluent. Conductivity detection was used in both cases. Detection limits for anions were in the range 2-27.4ppb, and for cations were in the range 13-115ppb. These methods allowed the explosive residue ions to be identified and separated from background ions likely to be present in the environment. Linearity (over a calibration range of 0.05-50ppm) was evaluated for both methods, with r(2) values ranging from 0.9889 to 1.000. Reproducibility over 10 consecutive injections of a 5ppm standard ranged from 0.01 to 0.22% relative standard deviation (RSD) for retention time and 0.29 to 2.16%RSD for peak area. The anion and cation separations were performed simultaneously by using two Dionex ICS-2000 chromatographs served by a single autoinjector. The efficacy of the developed methods was demonstrated by analysis of residue samples taken from witness plates and soils collected following the controlled detonation of a series of different inorganic homemade explosives. The results obtained were also confirmed by parallel analysis of the same samples by capillary electrophoresis (CE) with excellent agreement being obtained.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoegg, Edward D.; Barinaga, Charles J.; Hager, George J.

Abstract The continued development of the liquid sampling-atmospheric pressure glow discharge (LS-APGD) microplasma as an ion source for diverse, elemental/isotopic analysis applications continues. To this end, characterization of the capabilities in performing precise and accurate isotope ratio (IR) determinations is essential. Based on past experience with the Thermo Exactive Orbitrap mass analyzer, the LS-APGD was interfaced with this instrument for these tests. While the Orbitrap platform has demonstrated excellent mass resolution and accuracy in “organic” mass spectrometry (MS) applications, work using an Orbitrap for IR analysis is very sparse. These efforts build off previous work in this coupling, where themore » importance of a few of the LS-APGD discharge parameters and Orbitrap data acquisition methods on IR precision and accuracy were probed. Presented here are the results of a study that evaluated the analytical precision for natural uranium sample (assumed 235U/238U = 0.0072) determinations. The instrumental parameters evaluated include the number of microscans and scans making up a data acquisition set, uranium concentration/signal level, sample make-up, and Fourier transform digitization window. Ultimately, a precision of 0.41% relative standard deviation (RSD) can be achieved for a single determination, with a reproducibility of 1.63 %RSD over 10 separate analytical measurements. A preliminary study of matrix effects on IR measurements of U is presented, highlighting the importance of pre-mass selection before injection into the Orbitrap. The analytical system sensitivity is suggested with the ability to produce a calibration function having an R2 value of >0.99 over a range of 4 orders of magnitude of concentration (~1 – 1000 ng mL-1). These efforts demonstrate the very promising pairing of the LS-APGD ionization source and the Orbitrap, pointing as well to definitive paths forward to better utilize both components in high quality isotope ratio mass spectrometry (IRMS).« less

Mapping of the Rsd Contact Site on the Sigma 70 Subunit of Escherichia coli RNA Polymerase

PubMed Central

Jishage, Miki; Dasgupta, Dipak; Ishihama, Akira

2001-01-01

Rsd (regulator of sigma D) is an anti-sigma factor for the Escherichia coli RNA polymerase ς70 subunit. The contact site of Rsd on ς70 was analyzed after mapping of the contact-dependent cleavage sites by Rsd-tethered iron-p-bromoacetamidobenzyl EDTA and by analysis of the complex formation between Ala-substituted ς70 and Rsd. Results indicate that the Rsd contact site is located downstream of the promoter −35 recognition helix-turn-helix motif within region 4, overlapping with the regions involved in interaction with both core enzyme and ς70 contact transcription factors. PMID:11292818

Mapping of the Rsd contact site on the sigma 70 subunit of Escherichia coli RNA polymerase.

PubMed

Jishage, M; Dasgupta, D; Ishihama, A

2001-05-01

Rsd (regulator of sigma D) is an anti-sigma factor for the Escherichia coli RNA polymerase sigma(70) subunit. The contact site of Rsd on sigma(70) was analyzed after mapping of the contact-dependent cleavage sites by Rsd-tethered iron-p-bromoacetamidobenzyl EDTA and by analysis of the complex formation between Ala-substituted sigma(70) and Rsd. Results indicate that the Rsd contact site is located downstream of the promoter -35 recognition helix-turn-helix motif within region 4, overlapping with the regions involved in interaction with both core enzyme and sigma(70) contact transcription factors.

Studies of the Escherichia coli Rsd-sigma70 complex.

PubMed

Westblade, Lars F; Ilag, Leopold L; Powell, Andrew K; Kolb, Annie; Robinson, Carol V; Busby, Stephen J W

2004-01-16

Escherichia coli Rsd protein was previously identified on the basis of its binding to the RNA polymerase sigma(70) subunit. The Rsd-sigma(70) complex has been studied using different methods. Our data show that Rsd associates with sigma(70) to form a complex with a stoichiometry of 1:1. Alanine scanning and deletion mutagenesis were used to locate regions of sigma(70) that are required for the formation of the Rsd-sigma(70) complex.

The C2H2 Transcription Factor REGULATOR OF SYMBIOSOME DIFFERENTIATION Represses Transcription of the Secretory Pathway Gene VAMP721a and Promotes Symbiosome Development in Medicago truncatula[W][OPEN

PubMed Central

Sinharoy, Senjuti; Torres-Jerez, Ivone; Bandyopadhyay, Kaustav; Kereszt, Attila; Pislariu, Catalina I.; Nakashima, Jin; Benedito, Vagner A.; Kondorosi, Eva; Udvardi, Michael K.

2013-01-01

Transcription factors (TFs) are thought to regulate many aspects of nodule and symbiosis development in legumes, although few TFs have been characterized functionally. Here, we describe REGULATOR OF SYMBIOSOME DIFFERENTIATION (RSD) of Medicago truncatula, a member of the Cysteine-2/Histidine-2 (C2H2) family of plant TFs that is required for normal symbiosome differentiation during nodule development. RSD is expressed in a nodule-specific manner, with maximal transcript levels in the bacterial invasion zone. A tobacco (Nicotiana tabacum) retrotransposon (Tnt1) insertion rsd mutant produced nodules that were unable to fix nitrogen and that contained incompletely differentiated symbiosomes and bacteroids. RSD protein was localized to the nucleus, consistent with a role of the protein in transcriptional regulation. RSD acted as a transcriptional repressor in a heterologous yeast assay. Transcriptome analysis of an rsd mutant identified 11 genes as potential targets of RSD repression. RSD interacted physically with the promoter of one of these genes, VAMP721a, which encodes vesicle-associated membrane protein 721a. Thus, RSD may influence symbiosome development in part by repressing transcription of VAMP721a and modifying vesicle trafficking in nodule cells. This establishes RSD as a TF implicated directly in symbiosome and bacteroid differentiation and a transcriptional regulator of secretory pathway genes in plants. PMID:24082011

The C2H2 transcription factor regulator of symbiosome differentiation represses transcription of the secretory pathway gene VAMP721a and promotes symbiosome development in Medicago truncatula.

PubMed

Sinharoy, Senjuti; Torres-Jerez, Ivone; Bandyopadhyay, Kaustav; Kereszt, Attila; Pislariu, Catalina I; Nakashima, Jin; Benedito, Vagner A; Kondorosi, Eva; Udvardi, Michael K

2013-09-01

Transcription factors (TFs) are thought to regulate many aspects of nodule and symbiosis development in legumes, although few TFs have been characterized functionally. Here, we describe regulator of symbiosome differentiation (RSD) of Medicago truncatula, a member of the Cysteine-2/Histidine-2 (C2H2) family of plant TFs that is required for normal symbiosome differentiation during nodule development. RSD is expressed in a nodule-specific manner, with maximal transcript levels in the bacterial invasion zone. A tobacco (Nicotiana tabacum) retrotransposon (Tnt1) insertion rsd mutant produced nodules that were unable to fix nitrogen and that contained incompletely differentiated symbiosomes and bacteroids. RSD protein was localized to the nucleus, consistent with a role of the protein in transcriptional regulation. RSD acted as a transcriptional repressor in a heterologous yeast assay. Transcriptome analysis of an rsd mutant identified 11 genes as potential targets of RSD repression. RSD interacted physically with the promoter of one of these genes, VAMP721a, which encodes vesicle-associated membrane protein 721a. Thus, RSD may influence symbiosome development in part by repressing transcription of VAMP721a and modifying vesicle trafficking in nodule cells. This establishes RSD as a TF implicated directly in symbiosome and bacteroid differentiation and a transcriptional regulator of secretory pathway genes in plants.

The Escherichia coli Regulator of Sigma 70 Protein, Rsd, Can Up-Regulate Some Stress-Dependent Promoters by Sequestering Sigma 70▿

PubMed Central

Mitchell, Jennie E.; Oshima, Taku; Piper, Sarah E.; Webster, Christine L.; Westblade, Lars F.; Karimova, Gouzel; Ladant, Daniel; Kolb, Annie; Hobman, Jon L.; Busby, Stephen J. W.; Lee, David J.

2007-01-01

The Escherichia coli Rsd protein forms complexes with the RNA polymerase σ70 factor, but its biological role is not understood. Transcriptome analysis shows that overexpression of Rsd causes increased expression from some promoters whose expression depends on the alternative σ38 factor, and this was confirmed by experiments with lac fusions at selected promoters. The LP18 substitution in Rsd increases the Rsd-dependent stimulation of these promoter-lac fusions. Analysis with a bacterial two-hybrid system shows that the LP18 substitution in Rsd increases its interaction with σ70. Our experiments support a model in which the role of Rsd is primarily to sequester σ70, thereby increasing the levels of RNA polymerase containing the alternative σ38 factor. PMID:17351046

Solid-phase extraction-gas chromatography and solid-phase extraction-gas chromatography-mass spectrometry determination of corrosion inhibiting long-chain primary alkyl amines in chemical treatment of boiler water in water-steam systems of power plants.

PubMed

Kusch, Peter; Knupp, Gerd; Hergarten, Marcus; Kozupa, Marian; Majchrzak, Maria

2006-04-28

Gas chromatography with simultaneous flame-ionization detection (FID) and a nitrogen-phosphorus detection (NPD) as well as gas chromatography-mass spectrometry (GC/MS) has been used to characterize long-chain primary alkyl amines after derivatization with trifluoroacetic anhydride (TFAA). Electron impact ionization- (EI) and negative chemical ionization (NCI) mass spectra of trifluoroacetylated derivatives of the identified tert-octadecylamines are presented for the first time. The corrosion inhibiting alkyl amines were applied in a water-steam circuit of energy systems in the power industry. Solid-phase extraction (SPE) with octadecyl bonded silica (C18) sorbents followed by gas chromatography were used for quantification of the investigated tert-octadecylamines in boiler water, superheated steam and condensate samples from the power plant. The estimated values were: 89 microg l(-1)(n = 5, RSD = 7.8%), 45 microg l(-1) (n = 5, RSD = 5.4%) and 37 microg l(-1)(n = 5, RSD = 2.3%), respectively.

[Determination of 27 elements in Maca nationality's medicine by microwave digestion ICP-MS].

PubMed

Yu, Gui-fang; Zhong, Hai-jie; Hu, Jun-hua; Wang, Jing; Huang, Wen-zhe; Wang, Zhen-zhong; Xiao, Wei

2015-12-01

An analysis method has been established to test 27 elements (Li, Be, B, Mg, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Sr, Mo, Cd, Sn, Sb, Ba, La, Hg, Pb, Bi) in Maca nationality's medicine with microwave digestion-ICP-MS. Sample solutions were analyzed by ICP-MS after microwave digestion, and the contents of elements were calculated according to their calibration curves, and internal standard method was adopted to reduce matrix effect and other interference effects. The experimental results showed that the linear relations of all the elements were very good; the correlation coefficient (r) was 0.9994-1.0000 (Hg was 0.9982) ; the limits of detection were 0.003-2.662 microg x L(-1); the relative standard deviations for all elements of reproducibility were lower than 5% (except the individual elements); the recovery rate were 78.5%-123.7% with RSD lower than 5% ( except the individual elements). The analytical results of standard material showed acceptable agreement with the certified values. This method was applicable to determinate the contents of multi-elements in Maca which had a high sensitivity, good specificity and good repeatability, and provide basis for the quality control of Maca.

Quantitative 31P NMR for Simultaneous Trace Analysis of Organophosphorus Pesticides in Aqueous Media Using the Stir Bar Sorptive Extraction Method

NASA Astrophysics Data System (ADS)

Ansari, S.; Talebpour, Z.; Molaabasi, F.; Bijanzadeh, H. R.; Khazaeli, S.

2016-09-01

The analysis of pesticides in water samples is of primary concern for quality control laboratories due to the toxicity of these compounds and their associated public health risk. A novel analytical method based on stir bar sorptive extraction (SBSE), followed by 31P quantitative nuclear magnetic resonance (31P QNMR), has been developed for simultaneously monitoring and determining four organophosphorus pesticides (OPPs) in aqueous media. The effects of factors on the extraction efficiency of OPPs were investigated using a Draper-Lin small composite design. An optimal sample volume of 4.2 mL, extraction time of 96 min, extraction temperature of 42°C, and desorption time of 11 min were obtained. The results showed reasonable linearity ranges for all pesticides with correlation coefficients greater than 0.9920. The limit of quantification (LOQ) ranged from 0.1 to 2.60 mg/L, and the recoveries of spiked river water samples were from 82 to 94% with relative standard deviation (RSD) values less than 4%. The results show that this method is simple, selective, rapid, and can be applied to other sample matrices.

Synergy Effect of Nanocrystalline Cellulose for the Biosensing Detection of Glucose

PubMed Central

Esmaeili, Chakavak; Abdi, Mahnaz M.; Mathew, Aji P.; Jonoobi, Mehdi; Oksman, Kristiina; Rezayi, Majid

2015-01-01

Integrating polypyrrole-cellulose nanocrystal-based composites with glucose oxidase (GOx) as a new sensing regime was investigated. Polypyrrole-cellulose nanocrystal (PPy-CNC)-based composite as a novel immobilization membrane with unique physicochemical properties was found to enhance biosensor performance. Field emission scanning electron microscopy (FESEM) images showed that fibers were nanosized and porous, which is appropriate for accommodating enzymes and increasing electron transfer kinetics. The voltammetric results showed that the native structure and biocatalytic activity of GOx immobilized on the PPy-CNC nanocomposite remained and exhibited a high sensitivity (ca. 0.73 μA·mM−1), with a high dynamic response ranging from 1.0 to 20 mM glucose. The modified glucose biosensor exhibits a limit of detection (LOD) of (50 ± 10) µM and also excludes interfering species, such as ascorbic acid, uric acid, and cholesterol, which makes this sensor suitable for glucose determination in real samples. This sensor displays an acceptable reproducibility and stability over time. The current response was maintained over 95% of the initial value after 17 days, and the current difference measurement obtained using different electrodes provided a relative standard deviation (RSD) of 4.47%. PMID:26404269

A partial least squares based spectrum normalization method for uncertainty reduction for laser-induced breakdown spectroscopy measurements

NASA Astrophysics Data System (ADS)

Li, Xiongwei; Wang, Zhe; Lui, Siu-Lung; Fu, Yangting; Li, Zheng; Liu, Jianming; Ni, Weidou

2013-10-01

A bottleneck of the wide commercial application of laser-induced breakdown spectroscopy (LIBS) technology is its relatively high measurement uncertainty. A partial least squares (PLS) based normalization method was proposed to improve pulse-to-pulse measurement precision for LIBS based on our previous spectrum standardization method. The proposed model utilized multi-line spectral information of the measured element and characterized the signal fluctuations due to the variation of plasma characteristic parameters (plasma temperature, electron number density, and total number density) for signal uncertainty reduction. The model was validated by the application of copper concentration prediction in 29 brass alloy samples. The results demonstrated an improvement on both measurement precision and accuracy over the generally applied normalization as well as our previously proposed simplified spectrum standardization method. The average relative standard deviation (RSD), average of the standard error (error bar), the coefficient of determination (R2), the root-mean-square error of prediction (RMSEP), and average value of the maximum relative error (MRE) were 1.80%, 0.23%, 0.992, 1.30%, and 5.23%, respectively, while those for the generally applied spectral area normalization were 3.72%, 0.71%, 0.973, 1.98%, and 14.92%, respectively.

Determination of mercury by multisyringe flow injection system with cold-vapor atomic absorption spectrometry.

PubMed

Leal, L O; Elsholz, O; Forteza, R; Cerdà, V

2006-07-28

A new software-controlled time-based multisyringe flow injection system for mercury determination by cold-vapor atomic absorption spectrometry is proposed. Precise known volumes of sample, reducing agent (1.1% SnCl2 in 3% HCl) and carrier (3% HCl) are dispensed into a gas-liquid separation cell with a multisyringe burette coupled with one three-way solenoid valve. An argon flow delivers the reduced mercury to the spectrometer. The optimization of the system was carried out testing reaction coils and gas-liquid separators of different design as well as changing parameters, such as sample and reagents volumes, reagent concentrations and carrier gas flow rate, among others. The analytical curves were obtained within the range 50-5000 ng L(-1). The detection limit (3sigma(b)/S) achieved is 5 ng L(-1). The relative standard deviation (R.S.D.) was 1.4%, evaluated from 16 successive injections of 250 ng L(-1) Hg standard solution. The injection and sample throughput per hour were 44 and 11, respectively. This technique was validated by means of solid and water reference materials with good agreement with the certified values and was successfully applied to fish samples.

Synergy Effect of Nanocrystalline Cellulose for the Biosensing Detection of Glucose.

PubMed

Esmaeili, Chakavak; Abdi, Mahnaz M; Mathew, Aji P; Jonoobi, Mehdi; Oksman, Kristiina; Rezayi, Majid

2015-09-24

Integrating polypyrrole-cellulose nanocrystal-based composites with glucose oxidase (GOx) as a new sensing regime was investigated. Polypyrrole-cellulose nanocrystal (PPy-CNC)-based composite as a novel immobilization membrane with unique physicochemical properties was found to enhance biosensor performance. Field emission scanning electron microscopy (FESEM) images showed that fibers were nanosized and porous, which is appropriate for accommodating enzymes and increasing electron transfer kinetics. The voltammetric results showed that the native structure and biocatalytic activity of GOx immobilized on the PPy-CNC nanocomposite remained and exhibited a high sensitivity (ca. 0.73 μA·mM(-1)), with a high dynamic response ranging from 1.0 to 20 mM glucose. The modified glucose biosensor exhibits a limit of detection (LOD) of (50 ± 10) µM and also excludes interfering species, such as ascorbic acid, uric acid, and cholesterol, which makes this sensor suitable for glucose determination in real samples. This sensor displays an acceptable reproducibility and stability over time. The current response was maintained over 95% of the initial value after 17 days, and the current difference measurement obtained using different electrodes provided a relative standard deviation (RSD) of 4.47%.

In vivo study on the neurotransmitters and their metabolites change in depressive disorder rat plasma by ultra high performance liquid chromatography coupled to tandem mass spectrometry.

PubMed

Zhao, Longshan; Zheng, Shuning; Su, Guangyue; Lu, Xiumei; Yang, Jingyu; Xiong, Zhili; Wu, Chunfu

2015-04-15

A sensitive and versatile, ultra-high performance, liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method coupled to pre-column derivatization for the simultaneous determination of 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), dopamine (DA), norepinephrine (NE), homovanillic acid (HVA), γ-aminobutyric acid (GABA) and glutamic acid (Glu) was developed and validated in rat plasma. The analytes were dansylated under strong alkaline conditions after protein precipitation extraction, which were analyzed on a BEH C18 column using a gradient elution. The lower limit of quantification (LLOQ) values for 5-HT, 5-HIAA, DA, NE, HVA, GABA and Glu were 1.00, 1.00, 0.991, 0.992, 1.02, 1000, and 5030 pmol/mL, respectively. Good linearity was obtained (r > 0.99) and the intra- and inter-day precisions of the method (relative standard deviation, RSD%) were lower than 12%. The method was novel, sensitive and specific which can provide an alternative method for the quantification of neurotransmitters and their metabolites in plasma samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of selected non-authorized insecticides in peppers by liquid chromatography time-of-flight mass spectrometry and tandem mass spectrometry.

PubMed

Mezcua, Milagros; Ferrer, Carmen; García-Reyes, Juan F; Martínez-Bueno, María Jesús; Albarracín, Micaela; Claret, María; Fernández-Alba, Amadeo R

2008-05-01

In this work, two analytical methods based on liquid chromatography coupled to electrospray time-of-flight mass spectrometry (LC/ESI-TOFMS) and tandem mass spectrometry (LC/ESI-MS/MS) are described for the identification, confirmation and quantitation of three insecticides non-authorized in the European Union (nitenpyram, isocarbophos and isofenphos-methyl) but detected in recent monitoring programmes in pepper samples. The proposed methodologies involved a sample extraction procedure using liquid-liquid partition with acetonitrile followed by a cleanup step based on dispersive solid-phase extraction. Recovery studies performed on peppers spiked at different fortification levels (10 and 50 microg kg(-1)) yielded average recoveries in the range 76-100% with relative standard deviation (RSD) (%) values below 10%. Identification, confirmation and quantitation were carried out by LC/TOFMS and LC/MS/MS using a hybrid triple quadrupole linear ion trap (QqLIT) instrument in multiple-reaction monitoring (MRM) mode. The obtained limits of quantitation (LOQs) were in the range 0.1-5 microg kg(-1), depending on each individual technique. Finally, the proposed methods were successfully applied to the analysis of suspected pepper samples. Copyright (c) 2008 John Wiley & Sons, Ltd.

Gas chromatographic sulphur speciation in heavy crude oil using a modified standard D5623 method and microfluidic Deans switching.

PubMed

Heshka, Nicole E; Choy, Joanne M; Chen, Jinwen

2017-12-29

A modification to American Society for Testing and Materials (ASTM) method D5623 is proposed to enable successful and repeatable analysis of heavy crude oil samples. A two-dimensional gas chromatography configuration was implemented, with separation of sulphur compounds occurring on two columns. A Deans switch is used to enable heart-cutting of volatile sulphur compounds onto a DB-Sulfur stationary phase, and separation occurs concurrently with the backflushing of the primary column. The use of a sulphur-selective detector increases selectivity, and 22 volatile sulphur species are quantified in less than 15min, which is almost half the time of the original ASTM method. Samples ranging from light distillation cuts to whole crudes (boiling from 100°C to >750°C) were analyzed with minimal sample preparation. The calculated limit of detection was 0.7mg/kg, repeatability was 3% relative standard deviation (RSD), and a linear range of 1-250mg/kg was obtained, with an R 2 value of 0.994 or better, depending on the compound. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Dispersive liquid-liquid microextraction for the determination of nitrophenols in soils by microvial insert large volume injection-gas chromatography-mass spectrometry.

PubMed

Cacho, J I; Campillo, N; Viñas, P; Hernández-Córdoba, M

2016-07-22

A rapid and sensitive procedure for the determination of six NPs in soils by gas chromatography and mass spectrometry (GC-MS) is proposed. Ultrasound assisted extraction (UAE) is used for NP extraction from soil matrices to an organic solvent, while the environmentally friendly technique dispersive liquid-liquid microextraction (DLLME) is used for the preconcentration of the resulting UAE extracts. NPs were derivatized by applying an "in-situ" acetylation procedure, before being injected into the GC-MS system using microvial insert large volume injection (LVI). Several parameters affecting UAE, DLLME, derivatization and injection steps were investigated. The optimized procedure provided recoveries of 86-111% from spiked samples. Precision values of the procedure (expressed as relative standard deviation, RSD) lower than 12%, and limits of quantification ranging from 1.3 to 2.6ngg(-1), depending on the compound, were obtained. Twenty soil samples, obtained from military, industrial and agricultural areas, were analyzed by the proposed method. Two of the analytes were quantified in two of the samples obtained from industrial areas, at concentrations in the 4.8-9.6ngg(-1) range. Copyright © 2016 Elsevier B.V. All rights reserved.

Simultaneous gas chromatographic determination of chlorpyrifos and its impurity sulfotep in liquid pesticide formulations.

PubMed

Płonka, Marlena; Walorczyk, Stanisław; Miszczyk, Marek; Kronenbach-Dylong, Dorota

2016-11-01

An analytical method for simultaneous determination of the active substance (chlorpyrifos) and its relevant impurity (sulfotep) in commercial pesticide formulations has been developed and validated. The proposed method entails extraction of the analytes from samples by sonication with acetone and analysis by gas chromatography-flame ionization detection (GC-FID). The proposed method was characterized by satisfactory accuracy and precision. The repeatability expressed as relative standard deviation (RSD) was lower than the acceptable values calculated from the modified Horwitz equation whereas individual recoveries were in the range of 98-102% and 80-120% for chlorpyrifos and sulfotep, respectively. The limit of quantification (LOQ) for the impurity (sulfotep) was 0.003 mg mL(-1) corresponding to the maximum permitted level according to Food and Agricultural Organization of the United Nations (FAO) specifications for the active substance (chlorpyrifos) being 3 g kg(-1) of the chlorpyrifos content found. The main advantage of the proposed method was a considerable reduction in the analysis time since both analytes were determined based on a single injection into the GC-FID. Analysis of real samples of commercial pesticide formulations confirmed fitness-for-purpose of the proposed method.

[Fast separation and analysis of water-soluble vitamins in spinach by capillary electrophoresis with high voltage].

PubMed

Hu, Xiaoqin; You, Huiyan

2009-11-01

In capillary electrophoresis, 0-40 kV (even higher) voltage can be reached by a connecting double-model high voltage power supply. In the article, water-soluble vitamins, VB1, VB2, VB6, VC, calcium D-pantothenate, D-biotin, nicotinic acid and folic acid in vegetable, were separated by using the high voltage power supply under the condition of electrolyte water solution as running buffer. The separation conditions, such as voltage, the concentration of buffer and pH value etc. , were optimized during the experiments. The results showed that eight water-soluble vitamins could be baseline separated in 2.2 min at 40 kV applied voltage, 25 mmol/L sodium tetraborate buffer solution (pH 8.8). The water-soluble vitamins in spinach were quantified and the results were satisfied. The linear correlation coefficients of the water-soluble vitamins ranged from 0.9981 to 0.9999. The detection limits ranged from 0.2 to 0.3 mg/L. The average recoveries ranged from 88.0% to 100.6% with the relative standard deviations (RSD) range of 1.15%-4.13% for the spinach samples.

On-line preconcentration/determination of lead in Ilex paraguariensis samples (mate tea) using polyurethane foam as filter and USN-ICP-OES.

PubMed

Marchisio, P F; Sales, A; Cerutti, S; Marchevski, E; Martinez, L D

2005-09-30

The present paper proposes an on-line preconcentration procedure for lead determination in Ilex paraguariensis (St. Hilaire) samples by ultrasonic nebulization associated to inductively coupled plasma optical emission spectrometry (USN-ICP-OES). It is based on the precipitation of lead(II) ion on a minicolumn packed with polyurethane foam using 2-(5-bromo-2-pyridilazo)-5-diethylaminophenol (5-Br-PADAP) as precipitating reagent. The collected analyte precipitate was quantitatively eluted from the minicolumn with 20% (v/v) nitric acid. An enhancement factor of 225-fold was obtained (15 for USN and 15 for preconcentration). The detection limit (DL) value for the preconcentration of 10.0 ml of sample was 40.0 ng/l. The relative standard deviation (R.S.D.) was 3.0% for a Pb concentration of 1 microg/l, calculated from the peak heights obtained. The calibration graph using the preconcentration system for lead was linear with a correlation coefficient of 0.9997, at levels near the detection limits up to at least 100 microg/l. The preconcentration procedure was successfully applied to the determination of lead in mate tea samples.

The Relation Between Reflex Sympathetic Dystrophy Syndrome and Trauma Severity in Patients With Distal Tibia Fracture

PubMed Central

Bahador, Reza; Mirbolook, Ahmadreza; Arbab, Sara; Derakhshan, Pooya; Gholizadeh, Amirmohammad; Abedi, Sadegh

2016-01-01

Background Reflex sympathetic dystrophy (RSD) syndrome is a multifactorial disorder with clinical features of neurogenic inflammation that causes hypersensitivity to pain or severe allodynia as well as blood flow problems, swelling, skin discoloration and maladaptive neuroplasticity due to vasomotor disorders. Patients with major trauma are prone to homeostasis leading to inflammatory response syndrome and multiple organ distress syndrome. Several studies have investigated the etiology of this condition, but the cause remains unknown. The role of associated factors such as the limb immobilization technique and genetics has been reported in the development of this complication, but, so far, there is no information regarding the effect of trauma severity on the risk of RSD occurrence. Objectives Given the importance of diagnosing and treating this condition, we aimed to study the effect of trauma severity on the prevalence of RSD. Patients and Methods In this cross-sectional study, we examined patients with distal tibial fracture who visited Rasht Poursina hospital from 2010 to 2013. Exclusion criteria included associated fractures, underlying musculoskeletal diseases and mental and cognitive problems. To assess the severity of the initial injury in patients, the Hannover Fracture Scale 98 (HFS98) scoring checklist was used. The diagnosis of RSD was made on the basis of the IASP criterion. Demographic data, HFS98 scores, and information regarding RSD prevalence were analyzed using SPSS version 20. The Mann Whitney U nonparametric test was used for variables that were not normally distributed; the chi-square test was used to compare the qualitative variables. Results Among the 488 patients, 292 (59.83%) were male. The mean age of the study population was 44 ± 9.82 years. During the 6-month follow-up, RSD occurred in 45 patients, of whom 28 (62.22%) were female and 17 (37.77%) were male; there was thus a significant difference in the prevalence of RSD in terms of gender (P = 0.00; chi square test). The mean HFS98 score in patients without and with RSD was 3.081 ± 4.083 and 4.080 ± 4.622, respectively, and the difference was not statistically significant (P = 0.363; Mann Whitney U test). Analyses of the eight items of HFS98 shows that local circulation in patients with RSD is significantly better than that in patients without RDS (0.683 ± 0.822 vs. 0.528 ± 0.629, respectively). Statistical analysis showed that the odds ratio for RSD for patients with HFS95 score > 0 was 1.079 (confidence interval [CI]: 0.898 - 1.333). Moreover, the odds ratio for RSD was 1.100 (CI: 795 - 1.531) in patients with an injury severity score higher than the calculated mean score in patients without RSD (> 4.083). Conclusions The results suggest no significant relationship between the severity of injury and risk of RSD occurrence, although the mean injury severity score was higher in patients with RSD than in those without RSD in this study population. The lower score of local circulation in patients with RSD than in those without RSD is a statistically significant finding and can be attributed to changes in the antioxidant levels at the injury site, which is one of the main mechanisms for the onset of RSD. Wound contamination was also justifiably higher in patients with RSD, although the difference was not statistically significant. In summary, the severity of injury alone cannot be a determining factor for predicting the probability of RSD. PMID:27626009

The Relation Between Reflex Sympathetic Dystrophy Syndrome and Trauma Severity in Patients With Distal Tibia Fracture.

PubMed

Bahador, Reza; Mirbolook, Ahmadreza; Arbab, Sara; Derakhshan, Pooya; Gholizadeh, Amirmohammad; Abedi, Sadegh

2016-05-01

Reflex sympathetic dystrophy (RSD) syndrome is a multifactorial disorder with clinical features of neurogenic inflammation that causes hypersensitivity to pain or severe allodynia as well as blood flow problems, swelling, skin discoloration and maladaptive neuroplasticity due to vasomotor disorders. Patients with major trauma are prone to homeostasis leading to inflammatory response syndrome and multiple organ distress syndrome. Several studies have investigated the etiology of this condition, but the cause remains unknown. The role of associated factors such as the limb immobilization technique and genetics has been reported in the development of this complication, but, so far, there is no information regarding the effect of trauma severity on the risk of RSD occurrence. Given the importance of diagnosing and treating this condition, we aimed to study the effect of trauma severity on the prevalence of RSD. In this cross-sectional study, we examined patients with distal tibial fracture who visited Rasht Poursina hospital from 2010 to 2013. Exclusion criteria included associated fractures, underlying musculoskeletal diseases and mental and cognitive problems. To assess the severity of the initial injury in patients, the Hannover Fracture Scale 98 (HFS98) scoring checklist was used. The diagnosis of RSD was made on the basis of the IASP criterion. Demographic data, HFS98 scores, and information regarding RSD prevalence were analyzed using SPSS version 20. The Mann Whitney U nonparametric test was used for variables that were not normally distributed; the chi-square test was used to compare the qualitative variables. Among the 488 patients, 292 (59.83%) were male. The mean age of the study population was 44 ± 9.82 years. During the 6-month follow-up, RSD occurred in 45 patients, of whom 28 (62.22%) were female and 17 (37.77%) were male; there was thus a significant difference in the prevalence of RSD in terms of gender (P = 0.00; chi square test). The mean HFS98 score in patients without and with RSD was 3.081 ± 4.083 and 4.080 ± 4.622, respectively, and the difference was not statistically significant (P = 0.363; Mann Whitney U test). Analyses of the eight items of HFS98 shows that local circulation in patients with RSD is significantly better than that in patients without RDS (0.683 ± 0.822 vs. 0.528 ± 0.629, respectively). Statistical analysis showed that the odds ratio for RSD for patients with HFS95 score > 0 was 1.079 (confidence interval [CI]: 0.898 - 1.333). Moreover, the odds ratio for RSD was 1.100 (CI: 795 - 1.531) in patients with an injury severity score higher than the calculated mean score in patients without RSD (> 4.083). The results suggest no significant relationship between the severity of injury and risk of RSD occurrence, although the mean injury severity score was higher in patients with RSD than in those without RSD in this study population. The lower score of local circulation in patients with RSD than in those without RSD is a statistically significant finding and can be attributed to changes in the antioxidant levels at the injury site, which is one of the main mechanisms for the onset of RSD. Wound contamination was also justifiably higher in patients with RSD, although the difference was not statistically significant. In summary, the severity of injury alone cannot be a determining factor for predicting the probability of RSD.

[Is the suicidal risk assessment scale RSD of predictive value?].

PubMed

Ducher, J L; Terra, J L

2006-10-01

A part (60% to 70%) of those who are going to act out their suicide consult a doctor the month before. Studies have shown the need to improve the practitioner's capacity to diagnose depression. The assessment of the suicidal risk is crucial. The search for suicidal risk factors helps to define the populations at risk. However, it doesn't provide information concerning the possibility of acting out in the short term. And how does one react when faced with those who do not present any of the risk factors? Psychometric instruments attempt to help the therapist in his/her reasoning. SUICIDAL RISK ASSESSMENT: Among them, the suicidal risk assessment scale RSD should be mentioned. Its objective is to estimate the seriousness of the suicidal risk, with 11 levels. It is built around a possible will to commit suicide rather than a single assessment of the frequency of suicidal ideas. Its construction in hierarchical order permits the progressive assessment of the suicidal risk, in the form of a semi-structured interview. Hence, the suicidal risk assessment scale RSD looks for the existence of death wishes (levels 1-2), of suicide ideations and its frequency (levels 3-4-5), and of a passive desire to die (level 6). Level 7 shows the onset of a decision making process, except that the patient is still inhibited by various important factors in his/her life. More often, the fear of inflicting immense suffering to his/her loved ones or for religious beliefs, is found. From level 8, determination has made way to hesitation. An active death wish exists, and although the plan remains undefined, the act is decided on. At level 9 the methods of application are developed and a plan is established. The ultimate level exists when there is a start in the preparation of the act of suicide (level 10). This hierarchical order has been confirmed by some epidemiological studies. The inclusion of the suicidal risk assessment scale RSD in a double-blind, placebo-controlled study, which tested the efficacy of fluvoxamine in reducing the risk of recurrence of depression over 18 months, appears of particular interest. In this multicentre study, patients of both sexes were included, aged between 18 and 70 years, presenting a major depressive episode with a MADRS equal to a minimum of 25, and having had a minimum of two episodes of major depression within the last five years. The resulting analysis carried out on 103 patients showed a satisfactory concurrent validity between the suicidal risk assessment scale RSD and the items "suicide" of the MADRS (rho=0.79; p=0.0001) and the Hamilton Depression Scale (rho=0.70; p=0.0001), and fairly satisfactory concurrent validity with the depression degree assessed by the MADRS overall score (rho=0.40; p=0.0001). The short-term follow-up under treatment revealed enhanced sensitivity of the RSD versus the MADRS. The improvement in suicidal risk, assessed by the RSD, was faster than the improvement in depression, which is interesting from a clinical point of view. The medium-term follow-up tested the predictive validity of RSD and confirmed a greater level of suicidal risk from a score of 7 on the RSD, with the death by suicide of 2 subjects among the 15 who exhibited a score between 7 and 10 on the RSD on inclusion. On the other hand, no acting out, no attempted suicides, and no suicides were noted in the group of 88 subjects whose RSD was lower or equal to 6 on inclusion (p=0.02 using Fisher's exact test). Thus, the RSD appears of interest, from a clinical point of view, by providing a -diagnostic, or a scientific approach.

KEY COMPARISON: Final report on CCQM-K63.a,b: Non-peptide hormones in serum: cortisol and progesterone

NASA Astrophysics Data System (ADS)

S-C Tai, Susan; Duewer, David L.

2010-01-01

Hormones are chemical messengers that regulate many life functions. Deviations from normal hormone levels can have serious health consequences. Accurate measurement of hormone levels in serum can be beneficial in diagnosing, monitoring, and treating a number of diseases. Two steroid hormones, cortisol and progesterone, were selected by the Organic Analysis Working Group (OAWG) to evaluate its member Institutes' measurement capabilities for this important class of measurand. Serum concentrations of cortisol range from 30 ng/mL to 230 ng/mL. Serum concentrations of progesterone in adult females range from 0.15 ng/mL to 25 ng/mL but can rise to approx230 ng/mL during pregnancy. The ability to measure cortisol is indicative of a laboratory's ability to measure steroid hormones at concentration levels similar to cortisol. The ability to measure progesterone is indicative of a laboratory's ability to measure steroid hormones with similar functional groups and concentration levels, such as testosterone. Pilot studies CCQM-P77.a and CCQM-P77.b on the determination of cortisol and progesterone in human serum were completed in 2006. There was good agreement among the results reported by participants who used isotope dilution/mass spectrometry (ID/MS) with either gas chromatography (GC) or liquid chromatography (LC). In 2007 the OAWG decided to proceed with key comparison (KC) CCQM-K63.a, cortisol in human serum, and CCQM-K63.b, progesterone in human serum. Thus, following established OAWG procedure, only results from participants that (1) used an ID/MS-based method, (2) participated in the relevant pilot study, and (3) used a metrologically traceable primary standard were to be eligible for use in calculating the key comparison reference value (KCRV) for each measurand. Six laboratories participated in CCQM-K63.a and eight laboratories participated in CCQM-K63.b. The same pooled frozen female serum material was used in both of the KCs. The mean value for the six ID/MS-based cortisol results is 100.4 ng/g with a relative standard deviation (%RSD) of 1.1%. The mean value for the seven ID/MS-based progesterone originally reported results is 2.83 with a %RSD of 1.8%. While a number of the reported results were not eligible to be used in establishing the KCRVs, the KCRVs as estimated from just the eligible results agree very well with these means. The excellent among-participant agreement indicates that ID/MS-based measurement procedures can provide precise and true results for steroid hormones at levels greater than about 1 ng/g. The progesterone result reported by a laboratory using a non-isotopically labelled internal standard was about 11% larger than the KCRV. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Rsd family proteins make simultaneous interactions with regions 2 and 4 of the primary sigma factor

PubMed Central

Yuan, Andy H.; Gregory, Brian D.; Sharp, Josh S.; McCleary, Katherine D.; Dove, Simon L.; Hochschild, Ann

2008-01-01

Summary Bacterial anti-σ factors typically regulate σ factor function by restricting the access of their cognate σ factors to the RNA polymerase (RNAP) core enzyme. The E. coli Rsd protein forms a complex with the primary σ factor, σ70, inhibits σ70-dependent transcription in vitro, and has been proposed to function as a σ70-specific anti-σ factor, thereby facilitating the utilization of alternative σ factors. In prior work, Rsd has been shown to interact with conserved region 4 of σ70, but it is not known whether this interaction suffices to account for the regulatory functions of Rsd. Here we show that Rsd and the Rsd ortholog AlgQ, a global regulator of gene expression in P. aeruginosa, interact with conserved region 2 of σ70. We show further that Rsd and AlgQ can interact simultaneously with regions 2 and 4 of σ70. Our findings establish that the abilities of Rsd and AlgQ to interact with σ70 region 2 are important determinants of their in vitro and in vivo activities. PMID:18826409

Rsd family proteins make simultaneous interactions with regions 2 and 4 of the primary sigma factor.

PubMed

Yuan, Andy H; Gregory, Brian D; Sharp, Josh S; McCleary, Katherine D; Dove, Simon L; Hochschild, Ann

2008-12-01

Bacterial anti-sigma factors typically regulate sigma factor function by restricting the access of their cognate sigma factors to the RNA polymerase (RNAP) core enzyme. The Escherichia coli Rsd protein forms a complex with the primary sigma factor, sigma(70), inhibits sigma(70)-dependent transcription in vitro, and has been proposed to function as a sigma(70)-specific anti-sigma factor, thereby facilitating the utilization of alternative sigma factors. In prior work, Rsd has been shown to interact with conserved region 4 of sigma(70), but it is not known whether this interaction suffices to account for the regulatory functions of Rsd. Here we show that Rsd and the Rsd orthologue AlgQ, a global regulator of gene expression in Pseudomonas aeruginosa, interact with conserved region 2 of sigma(70). We show further that Rsd and AlgQ can interact simultaneously with regions 2 and 4 of sigma(70). Our findings establish that the abilities of Rsd and AlgQ to interact with sigma(70) region 2 are important determinants of their in vitro and in vivo activities.

Development and Application of an HPLC–UV Procedure to Determine Multiple Flavonoids and Phenolics in Acanthopanax Leaf Extracts

PubMed Central

Zhang, Xiaodan; Zhou, Xinqi; Liu, Xiangqian; Li, Xiaolong; Whang, Wankyunn

2016-01-01

Acanthopanax species are used in traditional medicine to treat numerous diseases. A simultaneous high-performance liquid chromatography (HPLC) method was developed and validated for the determination of the flavonoid and phenolic content of Acanthopanax leaves. HPLC analysis was performed on an AKZO NOBEL Kromasil 100-5C18 column (250 × 4.6 mm, 5 µm) using a gradient elution of acetonitrile–water containing 0.2% formic acid with a flow rate of 1.0 mL/min, monitored at 320 nm. The method was linear over the range 1–500 µg/mL (determination coefficients R2 > 0.999). Satisfactory intraday and interday precision was achieved, with the relative standard deviation (RSD) <2.99%. The mean recoveries measured at the three concentrations were in the range of 90.11–104.83%, with RSD <2.91% for the targets. Twenty-four samples of Acanthopanax leaves from different species and locations were examined using this analytical method, and their chemical profiles provided information for the chemotaxonomic investigation. The established method is simple, rapid and reliable for the quality control of Acanthopanax leaves of various species from different collections. The complete phenolic and flavonoid profiles of Acanthopanax leaves of various species have been established. PMID:26711585

Development of a Rapid LC-MS/MS Method for the Determination of Emerging Fusarium mycotoxins Enniatins and Beauvericin in Human Biological Fluids

PubMed Central

Serrano, Ana Belén; Capriotti, Anna Laura; Cavaliere, Chiara; Piovesana, Susy; Samperi, Roberto; Ventura, Salvatore; Laganà, Aldo

2015-01-01

A novel method for the simultaneous determination of enniatins A, A1, B and B1 and beauvericin, both in human urine and plasma samples, was developed and validated. The method consisted of a simple and easy pretreatment, specific for each matrix, followed by solid phase extraction (SPE) and detection by high performance liquid chromatography-tandem mass spectrometry with an electrospray ion source. The optimized SPE method was performed on graphitized carbon black cartridges after suitable dilution of the extracts, which allowed high mycotoxin absolute recoveries (76%–103%) and the removal of the major interferences from the matrix. The method was extensively evaluated for plasma and urine samples separately, providing satisfactory results in terms of linearity (R2 of 0.991–0.999), process efficiency (>81%), trueness (recoveries between 85% and 120%), intra-day precision (relative standard deviation, RSD < 18%), inter-day precision (RSD < 21%) and method quantification limits (ranging between 20 ng·L−1 and 40 ng·L−1 in plasma and between 5 ng·L−1 and 20 ng·L−1 in urine). Finally, the highly sensitive validated method was applied to some urine and plasma samples from different donors. PMID:26371043

Investigation of the binding of AuNPs-6-mercaptopurine and the sensitive detection of 6-mercaptopurine using resonance Rayleigh light scattering.

PubMed

Li, Zhihong; Bi, Shuyun; Wang, Tianjiao; Wang, Yu; Zhou, Huifeng; Wu, Jun

2017-06-01

A highly sensitive method for the detection of 6-mercaptopurine (MP) by resonance Rayleigh light scattering (RLS) method was developed. Gold nanoparticles (AuNPs) were synthesized by a modified seed method and characterized using transmission electron microscopy (TEM). AuNPs were bound to MP via covalent bonding to form the MP-AuNPs complex, which increased the RLS intensity of MP at 347 nm (increased by 65.7%). Under optimum conditions, the magnitude of the enhanced RLS intensity for MP-AuNPs was proportional to MP concentration in the range 0.0681-1.702 μg mL -1 . The linear regression equation was represented as follows: ΔI RLS  = 9.31 + 82.42c (r = 0.9948). The limit of detection (LOD, 3σ) was 3.32 ng mL -1 . The system was applied successfully to detect MP in pharmaceuticals. MP recoveries were 99.9-101.7% with a relative standard deviation (RSD) (n = 5) of 0.59-0.77% for three synthetic samples, and 97.5-110.0% with an RSD of 0.98-2.10% (n = 5) for tablet samples. Copyright © 2016 John Wiley & Sons, Ltd.

A naturally occurring diatom frustule as a SERS substrate for the detection and quantification of chemicals

NASA Astrophysics Data System (ADS)

Chamuah, Nabadweep; Chetia, Lakhi; Zahan, Nashrat; Dutta, Sibasish; Ahmed, Gazi A.; Nath, Pabitra

2017-05-01

Naturally occurring photonic crystal structures play an important role in different fields of application. Herein, we exploit the periodic pore pattern of a diatom frustule and demonstrate surface-enhanced Raman scattering (SERS) using its structure as a template for the SERS substrate. Gold nanoparticles (AuNPs) were initially allowed to self-assemble on the surface and inside the pores of the diatoms. The enhancement in the localized surface plasmon resonance (LSPR) field magnitude for the assembled AuNPs on the diatom frustule were studied using simulation software. For the proposed SERS substrate, an average field enhancement of the order of 108 magnitude was observed. We demonstrate the operation of the designed substrate for the detection and quantification of Raman signals from two Raman active samples, namely malachite green (MG) and fluoride concentrations in drinking water. Using the proposed SERS substrate, an MG concentration as low as 1 nM with a relative standard deviation (RSD) of 7.57% and a fluoride concentration of 100 nM with an RSD of 17.26% could be measured with the Raman spectrometer. We envision that the proposed technique could emerge as an inexpensive alternative fabrication method of SERS substrates which can produce an enhanced LSPR field magnitude and scatter intense Raman signals from Raman active samples.

Simultaneous detection of imidacloprid and parathion by the dual-labeled time-resolved fluoroimmunoassay.

PubMed

Shi, Haiyan; Sheng, Enze; Feng, Lu; Zhou, Liangliang; Hua, Xiude; Wang, Minghua

2015-10-01

A highly sensitive direct dual-labeled time-resolved fluoroimmunoassay (TRFIA) to detect parathion and imidacloprid simultaneously in food and environmental matrices was developed. Europium (Eu(3+)) and samarium (Sm(3+)) were used as fluorescent labels by coupling separately with L1-Ab and A1P1-Ab. Under optimal assay conditions, the half-maximal inhibition concentration (IC50) and limit of detection (LOD, IC10) were 10.87 and 0.025 μg/L for parathion and 7.08 and 0.028 μg/L for imidacloprid, respectively. The cross-reactivities (CR) were negligible except for methyl-parathion (42.4 %) and imidaclothiz (103.4 %). The average recoveries of imidacloprid ranged from 78.9 to 104.2 % in water, soil, rice, tomato, and Chinese cabbage with a relative standard deviation (RSD) of 2.4 to 11.6 %, and those of parathion were from 81.5 to 110.9 % with the RSD of 3.2 to 10.5 %. The results of TRFIA for the authentic samples were validated by comparison with gas chromatography (GC) analyses, and satisfactory correlations (parathion: R (2) = 0.9918; imidacloprid: R (2) = 0.9908) were obtained. The results indicate that the dual-labeled TRFIA is convenient and reliable to detect parathion and imidacloprid simultaneously in food and environmental matrices.

Sample preparation for total reflection X-ray fluorescence analysis using resist pattern technique

NASA Astrophysics Data System (ADS)

Tsuji, K.; Yomogita, N.; Konyuba, Y.

2018-06-01

A circular resist pattern layer with a diameter of 9 mm was prepared on a glass substrate (26 mm × 76 mm; 1.5 mm thick) for total reflection X-ray fluorescence (TXRF) analysis. The parallel cross pattern was designed with a wall thickness of 10 μm, an interval of 20 μm, and a height of 1.4 or 0.8 μm. This additional resist layer did not significantly increase background intensity on the XRF peaks in TXRF spectra. Dotted residue was obtained from a standard solution (10 μL) containing Ti, Cr, Ni, Pb, and Ga, each at a final concentration of 10 ppm, on a normal glass substrate with a silicone coating layer. The height of the residue was more than 100 μm, where self-absorption in the large residue affected TXRF quantification (intensity relative standard deviation (RSD): 12-20%). In contrast, from a droplet composed of a small volume of solution dropped and cast on the resist pattern structure, the obtained residue was not completely film but a film-like residue with a thickness less than 1 μm, where self-absorption was not a serious problem. In the end, this sample preparation was demonstrated to improve TXRF quantification (intensity RSD: 2-4%).

Whole air canister sampling coupled with preconcentration GC/MS analysis of part-per-trillion levels of trimethylsilanol in semiconductor cleanroom air.

PubMed

Herrington, Jason S

2013-08-20

The costly damage airborne trimethylsilanol (TMS) exacts on optics in the semiconductor industry has resulted in the demand for accurate and reliable methods for measuring TMS at trace levels (i.e., parts per trillion, volume per volume of air [ppt(v)] [~ng/m(3)]). In this study I developed a whole air canister-based approach for field sampling trimethylsilanol in air, as well as a preconcentration gas chromatography/mass spectrometry laboratory method for analysis. The results demonstrate clean canister blanks (0.06 ppt(v) [0.24 ng/m(3)], which is below the detection limit), excellent linearity (a calibration relative response factor relative standard deviation [RSD] of 9.8%) over a wide dynamic mass range (1-100 ppt(v)), recovery/accuracy of 93%, a low selected ion monitoring method detection limit of 0.12 ppt(v) (0.48 ng/m(3)), replicate precision of 6.8% RSD, and stability (84% recovery) out to four days of storage at room temperature. Samples collected at two silicon wafer fabrication facilities ranged from 10.0 to 9120 ppt(v) TMS and appear to be associated with the use of hexamethyldisilazane priming agent. This method will enable semiconductor cleanroom managers to monitor and control for trace levels of trimethylsilanol.

Determination of benzimidazole anthelmintics in milk and honey by monolithic fiber-based solid-phase microextraction combined with high-performance liquid chromatography-diode array detection.

PubMed

Zhang, Yong; Huang, Xiaojia; Yuan, Dongxing

2015-01-01

A porous poly(methacrylic acid-co-ethylene dimethacrylate) monolithic fiber (MEMF) for solid-phase microextraction (SPME) of five benzimidazole anthelmintics was prepared by in-situ polymerization. The effect of polymerization conditions on SPME of the target analytes was studied thoroughly. The physicochemical properties of the monolith were characterized by infrared spectroscopy, elemental analysis, scanning electron microscopy, and mercury intrusion porosimetry. Several conditions affecting the extraction efficiency were investigated and, under the optimized conditions, a simple and sensitive method for the determination of trace benzimidazoles residues in milk and honey was established by coupling MEMF-SPME with high-performance liquid chromatography-diode array detection (MEMF-SPME-HPLC-DAD). Under the optimum experimental conditions, the limits of detection (S/N = 3) of the method were 0.11-0.30 μg L(-1) for milk and 0.086-0.28 μg L(-1) for honey. Evaluation of intra-day and inter-day precision showed reproducibility was satisfactory-relative standard deviations (RSD) for both were <10 %. Finally, the method was successfully used for determination of benzimidazole residues in milk and honey. Recoveries obtained for determination of benzimidazole anthelmintics in spiked samples ranged from 72.3 to 121 %, with RSD always <11 %.

Changes of serum neurohormone after renal sympathetic denervation in dogs with pacing-induced heart failure.

PubMed

Zhao, Qingyan; Huang, He; Wang, Xule; Wang, Xiaozhan; Dai, Zixuan; Wan, Peixing; Guo, Zongwen; Yu, Shengbo; Tang, Yanhong; Huang, Congxin

2014-01-01

Neurohormonal activation is a commonly cited array of phenomena in the body's physiologic response to heart failure (HF). The aim of the present study was to determine the change law of serum neurohormones after renal sympathetic denervation (RSD) in dogs with pacing-induced HF. Twenty-eight beagles were randomly divided into control group, RSD group, HF group and HF + RSD group. The control group was implanted pacemakers without pacing; the RSD group underwent renal artery ablation without pacing; the HF group was implanted pacemakers with ventricular pacing at 240 bpm for 3 weeks; and HF + RSD group underwent renal artery ablation and with ventricular pacing at 240 bpm for 3 weeks. Blood samples were taken at baseline, and 3, 6, 9, 12, 15, 18, 21 days in all the dogs for neurohormones measurement. After 3 weeks, the systolic femoral artery pressures in the HF and HF + RSD groups were reduced after pacing 3 weeks. There was an increase significantly in BNP, angiotensin II, aldosterone, endothelin-1 and decrease in renalase after 3 weeks when compared with baseline in HF group. RSD significantly suppressed the changes of plasma neurohormones concentration in experimental HF, but RSD had not obviously impact on the levels of plasma neurohormones during 3 weeks in RSD group. RSD attenuates the changes of levels of plasma neurohormones in the activated renin-angiotensin-aldosterone system (RAAS) but had not obviously effect in the normal physiology of RAAS.

Efficacy and Safety of Renal Sympathetic Denervation on Dogs with Pressure Overload-Induced Heart Failure.

PubMed

Chen, Pingan; Leng, Shuilong; Luo, Yishan; Li, Shaonan; Huang, Zicheng; Liu, Zhenxi; Liu, Zhen; Wang, Jie; Lei, Xiaoming

2017-02-01

In dogs with heart failure (HF) induced by overload pressure, the role of renal sympathetic denervation (RSD) on heart failure and in the renal artery is unclear. Therefore, we investigated the efficacy and safety of RSD in dogs with pressure overload-induced heart failure. Twenty mongrel dogs were divided into a sham-operated group, an HF group and an HF + RSD group. In the sham-operated group, the abdominal aorta was located but was not constricted, in the HF group, the abdominal aorta was constricted without RSD, and the HF+RSD group underwent RSD with constriction of the abdominal aorta after 10 weeks. Blood sampling assays, echocardiography, intravascular ultrasound (IVUS) measurement and histopathological examination were performed. Renal sympathetic denervation caused a significant reduction in the levels of noradrenaline (166.62±6.84 vs. 183.48±13.66 pg/ml, P<0.05), plasma renin activity (1.93±0.12 vs. 2.10±0.13 ng/mlh, P<0.05) and B-type natriuretic peptide (71.14±3.86 vs. 83.15±5.73 pg/ml, P<0.05) at eight weeks after RSD in the HF+RSD group. Compared with the HF group at eight weeks, the left ventricular internal dimension at end-diastole and end-systole were lower and the left ventricular ejection fraction was higher (all P<0.05) at eight weeks after RSD in the HF+RSD group. Intravenous ultrasound images showed no changes in the renal artery lumen, and intimal hyperplasia and vascular lumen stenosis were not observed after RSD. Renal sympathetic denervation could improve cardiac function in dogs with HF induced by pressure overload; RSD had no adverse influence on the renal artery. Copyright © 2016 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

Stereospecific analysis of sakuranetin by high-performance liquid chromatography: pharmacokinetic and botanical applications.

PubMed

Takemoto, Jody K; Remsberg, Connie M; Yáñez, Jaime A; Vega-Villa, Karina R; Davies, Neal M

2008-11-01

A stereospecific method for analysis of sakuranetin was developed. Separation was accomplished using a Chiralpak AD-RH column with UV (ultraviolet) detection at 288 nm. The stereospecific linear calibration curves ranged from 0.5 to 100 microg/mL. The mean extraction efficiency was >98%. Precision of the assay was <12% (relative standard deviation (R.S.D.)%), and within 10% at the limit of quantitation (0.5 microg/mL). Bias of the assay was lower than 10%, and within 5% at the limit of quantitation. The assay was applied successfully to pharmacokinetic quantification in rats, and the stereospecific quantification in oranges, grapefruit juice, and matico (Piper aduncum L.).

Application of blood cadmium determination to industry using a punched disc technique.

PubMed Central

Cernik, A A; Sayers, M P

1975-01-01

A paper disc flameless atomic absorption spectroscopy (AAS) method is described for the determination of cadmium (Cd) in blood, enabling difficulties in sample preparation to be minimized. By control of the ashing step the matrix can be removed without loss of cadmium. Problems with the fast signal response during atomization can be met by spectral band width and temperature control. At the 106 pg level (471 nmol Cd/1 blood; 5-3 mug/100 ml) the relative standard deviation (RSD) was 0-06. Results in four industrial situations are reported. This description of the method should facilitate further investigation of its application to industry using capillary or venous blood. PMID:1131342

Development of an LC-MS/MS method for the determination of endogenous cortisol in hair using (13)C3-labeled cortisol as surrogate analyte.

PubMed

Binz, Tina M; Braun, Ueli; Baumgartner, Markus R; Kraemer, Thomas

2016-10-15

Hair cortisol levels are increasingly applied as a measure for stress in humans and mammals. Cortisol is an endogenous compound and is always present within the hair matrix. Therefore, "cortisol-free hair matrix" is a critical point for any analytical method to accurately quantify especially low cortisol levels. The aim of this project was to modify current methods used for hair cortisol analysis to more accurately determine low endogenous cortisol concentrations in hair. For that purpose, (13)C3-labeled cortisol, which is not naturally present in hair (above 13C natural abundance levels), was used for calibration and comparative validation applying cortisol versus (13)C3-labeled cortisol. Cortisol was extracted from 20mg hair (standard sample amount) applying an optimized single step extraction protocol. An LC-MS/MS method was developed for the quantitative analysis of cortisol using either cortisol or (13)C3-cortisol as calibrators and D7-cortisone as internal standard (IS). The two methods (cortisol/(13)C3-labeled cortisol) were validated in a concentration range up to 500pg/mg and showed good linearity for both analytes (cortisol: R(2)=0.9995; (13)C3-cortisol R(2)=0.9992). Slight differences were observed for limit of detection (LOD) (0.2pg/mg/0.1pg/mg) and limit of quantification (LOQ) (1pg/mg/0.5pg/mg). Precision was good with a maximum deviation of 8.8% and 10% for cortisol and (13)C3-cortisol respectively. Accuracy and matrix effects were good for both analytes except for the quality control (QC) low cortisol. QC low (2.5pg/mg) showed matrix effects (126.5%, RSD 35.5%) and accuracy showed a deviation of 26% when using cortisol to spike. These effects are likely to be caused by the unknown amount of endogenous cortisol in the different hair samples used to determine validation parameters like matrix effect, LOQ and accuracy. No matrix effects were observed for the high QC (400pg/mg) samples. Recovery was good with 92.7%/87.3% (RSD 9.9%/6.2%) for QC low and 102.3%/82.1% (RSD 5.8%/11.4%) for QC high. After successful validation the applicability of the method could be proven. The study shows that the method is especially useful for determining low endogenous cortisol concentrations as they occur in cow hair for example. Copyright © 2016 Elsevier B.V. All rights reserved.

Assessment of visual distortions in age-related macular degeneration: emergence of new approaches

PubMed Central

Vazquez, Noelia Pitrelli; Knox, Paul C.

2016-01-01

Aims With the arrival of effective treatments for neovascular age-related macular degeneration (nvAMD) there is a need to find improved tests that would allow early detection. Ideally, these tests would allow monitoring of vision by patients themselves from home. The aim of this review is to discuss the available evidence for two recently developed vision tests designed for this purpose: the Preferential Hyperacuity Perimeter (PHP) test and the Radial Shape Discrimination (RSD) test. Methods Articles that investigated detection of nvAMD were reviewed. The methodology of the clinical evidence, where available, was judged for bias and applicability of the results to the general population using the QUADAS-2 quality assessment tool. Results The PHP test has proved to be good at detecting nvAMD but many studies assessed in this review were biased in the selection of patients, restricting the results to only those patients who can use the test and produce reliable results. On the other hand the RSD test is a simple test, well accepted by elderly patients with AMD. However, clinical studies to determine its value in the detection of early signs of nvAMD are still required. Conclusions To date, more studies have investigated the utility of the PHP test compared with the RSD test for detection of nvAMD. Both tests show promise but further evidence is needed to determine the real generalisability of the PHP test and the sensitivity of the RSD test. PMID:27738450

A global view of Escherichia coli Rsd protein and its interactions.

PubMed

Piper, Sarah E; Mitchell, Jennie E; Lee, David J; Busby, Stephen J W

2009-12-01

The Escherichia coli Rsd protein forms 1 : 1 complexes with sigma(70) protein, which is the major factor in determining promoter recognition by RNA polymerase. Here we describe measurements of the levels of Rsd, RNA polymerase, sigma(70) and the alternative sigma(38) factor. Rsd levels are sufficient to sequester a significant proportion of sigma(70) and immunoaffinity pull-down experiments show that this occurs in stationary phase but not in exponentially growing cells. Rsd expression is controlled by two promoters, P1 and P2. Experiments with lac fusions show that the P2 promoter is stronger than P1, that P2 is active in all phases of growth, and that this accounts for the high levels of Rsd.

Estimation of chemical carcass composition from 8th rib characteristics with Belgian blue double-muscled bulls.

PubMed

De Campeneere, S; Fiems, L O; Van de Voorde, G; Vanacker, J M; Boucque, C V; Demeyer, D I

1999-01-01

Characteristics from the 8th rib cut: chemical composition, tissue composition after dissection, specific gravity (SG) and m. longissimus thoracis (LT) composition, collected on 17 Belgian Blue double-muscled fattening bulls were used to generate equations for predicting chemical carcass composition. Carcass composition was best predicted from chemical analysis of the 8th rib cut and the empty body weight (EBW) of the bull. Carcass chemical fat content (CCF, kg) was predicted from the 8th rib cut fat content (ether extract, 8RF, kg) by the following regression: CCF=1.94+27.37 8RF (R(2)=0.957, RSD =9.89%). A higher coefficient was found for carcass water (CCW, kg) predicted from 8RF and EBW: CCW=-2.26+0.28 EBW-34.28 8RF (R(2)=0.997, RSD=1.48%). No parameter was found to improve the prediction of CCP from EBW solely: CCP=-0.86+0.08 EBW (R(2) =0.992, RSD=2.61%). Prediction equations based solely on LT composition had low R(2) values of between 0.38 and 0.67, whereas no significant equations were found using SG. However, equations based on EBW had R(2) values between 0.78 and 0.99. Chemical components of the 8th rib cut in combination with EBW are most useful in predicting the chemical composition of the carcass of Belgian-Blue double-muscled bulls.

Vocational rehabilitation considerations for people with reflex sympathetic dystrophy.

PubMed

Smith, T S; Genoff, M C

1997-01-01

Reflex sympathetic dystrophy (RSD) is identified by the existence of pain, trophic changes, vasomotor instability, limited range of motion and swelling of an extremity. RSD is difficult to treat and prognosis is often poor. Although widely noted in the medical literature, the vocational rehabilitation literature has failed to address the potential role of vocational rehabilitation professionals in the social and economic employment outcome for people with RSD. Vocational rehabilitation professionals are defined as those performing vocational assessments, assessing transferable skills, determining adaptive skills, certifying residual work-related capacities, conducting vocational interest testing, coordinating efforts with pre-injury employers to assist in work reentry efforts, or performing other activities to assist in the placement or retraining of individuals with RSD. The sources used for this article include a review of the literature and observations of the authors. A vocational rehabilitation primer is provided. The following topics are addressed: the anatomical and physiological basis of RSD, treatment protocols, difficulties in accurately diagnosing RSD, influence of litigation, job placement considerations and vocational planning. As the vocational rehabilitation counsellor faces a greater number of people either diagnosed with RSD, or exhibiting RSD symptoms, he/she will be challenged to: (1) increase one's knowledge base about the etiology and treatment of RSD; (2) coordinate personal efforts with other professionals; and (3) provide personal counselling to address lifestyle and motivational factors.

Preprocedural Anxiety and Pain Perception Following Root Surface Debridement in Chronic Periodontitis Patients.

PubMed

Naik, Vanaja Krishna; Balasundaram, Aruna; Appukuttan, Devapriya; Nainar, Deepavalli Arumuga; Milward, Michael Robert; Victor, Dhayanand John; Junaid, Mohammed

2018-01-01

The aim of this study was to evaluate and compare preprocedural dental anxiety levels and postprocedural pain perception in chronic periodontitis patients during conventional-staged root surface debridement (RSD) and single-stage RSD. Thirty-seven adult generalized chronic periodontitis patients requiring RSD were recruited in this study. Preprocedural anxiety levels were assessed using a self-reported questionnaire and postprocedural pain perceptions were assessed using 0-10 cm visual analog scale. The subject population was divided into two groups: staged RSD ( n = 18) and single-stage RSD ( n = 19). Staged RSD patients visited four times as opposed to single-stage RSD patients. Data were subjected to Pearson Chi-square test, Mann-Whitney U-test, and Spearman's rank correlation. There was no statistically significant difference in dental anxiety levels or pain perceptions in both the groups. Within Group 1, there was statistical significant difference in dental anxiety levels between visit 4 and visit 3 ( P = 0.037) and pain perception between visit 3 and visit 1 ( P = 0.005), visit 4 and visit 1 ( P = 0.002), and visit 4 and visit 2 (0.04) was statistically significant. There was a positive correlation of anxiety questionnaire (Q1-Q4) to the pain score in Group 1 which was statistically significant and in single-stage RSD. Conventional quadrant-wise RSD tends to cognitively condition the anxiety experience thus influencing pain experience.

Rapid Development and Validation of Improved Reversed-Phase High-performance Liquid Chromatography Method for the Quantification of Mangiferin, a Polyphenol Xanthone Glycoside in Mangifera indica

PubMed Central

Naveen, P.; Lingaraju, H. B.; Prasad, K. Shyam

2017-01-01

Mangiferin, a polyphenolic xanthone glycoside from Mangifera indica, is used as traditional medicine for the treatment of numerous diseases. The present study was aimed to develop and validate a reversed-phase high-performance liquid chromatography (RP-HPLC) method for the quantification of mangiferin from the bark extract of M. indica. RP-HPLC analysis was performed by isocratic elution with a low-pressure gradient using 0.1% formic acid: acetonitrile (87:13) as a mobile phase with a flow rate of 1.5 ml/min. The separation was done at 26°C using a Kinetex XB-C18 column as stationary phase and the detection wavelength at 256 nm. The proposed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification, and robustness by the International Conference on Harmonisation guidelines. In linearity, the excellent correlation coefficient more than 0.999 indicated good fitting of the curve and also good linearity. The intra- and inter-day precision showed < 1% of relative standard deviation of peak area indicated high reliability and reproducibility of the method. The recovery values at three different levels (50%, 100%, and 150%) of spiked samples were found to be 100.47, 100.89, and 100.99, respectively, and low standard deviation value < 1% shows high accuracy of the method. In robustness, the results remain unaffected by small variation in the analytical parameters, which shows the robustness of the method. Liquid chromatography–mass spectrometry analysis confirmed the presence of mangiferin with M/Z value of 421. The assay developed by HPLC method is a simple, rapid, and reliable for the determination of mangiferin from M. indica. SUMMARY The present study was intended to develop and validate an RP-HPLC method for the quantification of mangiferin from the bark extract of M. indica. The developed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification and robustness by International Conference on Harmonization guidelines. This study proved that the developed assay by HPLC method is a simple, rapid and reliable for the quantification of the mangiferin from M. indica. Abbreviations Used: M. indica: Mangifera indica, RP-HPLC: Reversed-phase high-performance liquid chromatography, M/Z: Mass to charge ratio, ICH: International conference on harmonization, % RSD: Percentage of relative standard deviation, ppm: Parts per million, LOD: Limit of detection, LOQ: Limit of quantification. PMID:28539748

Rapid Development and Validation of Improved Reversed-Phase High-performance Liquid Chromatography Method for the Quantification of Mangiferin, a Polyphenol Xanthone Glycoside in Mangifera indica.

PubMed

Naveen, P; Lingaraju, H B; Prasad, K Shyam

2017-01-01

Mangiferin, a polyphenolic xanthone glycoside from Mangifera indica , is used as traditional medicine for the treatment of numerous diseases. The present study was aimed to develop and validate a reversed-phase high-performance liquid chromatography (RP-HPLC) method for the quantification of mangiferin from the bark extract of M. indica . RP-HPLC analysis was performed by isocratic elution with a low-pressure gradient using 0.1% formic acid: acetonitrile (87:13) as a mobile phase with a flow rate of 1.5 ml/min. The separation was done at 26°C using a Kinetex XB-C18 column as stationary phase and the detection wavelength at 256 nm. The proposed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification, and robustness by the International Conference on Harmonisation guidelines. In linearity, the excellent correlation coefficient more than 0.999 indicated good fitting of the curve and also good linearity. The intra- and inter-day precision showed < 1% of relative standard deviation of peak area indicated high reliability and reproducibility of the method. The recovery values at three different levels (50%, 100%, and 150%) of spiked samples were found to be 100.47, 100.89, and 100.99, respectively, and low standard deviation value < 1% shows high accuracy of the method. In robustness, the results remain unaffected by small variation in the analytical parameters, which shows the robustness of the method. Liquid chromatography-mass spectrometry analysis confirmed the presence of mangiferin with M/Z value of 421. The assay developed by HPLC method is a simple, rapid, and reliable for the determination of mangiferin from M. indica . The present study was intended to develop and validate an RP-HPLC method for the quantification of mangiferin from the bark extract of M. indica . The developed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification and robustness by International Conference on Harmonization guidelines. This study proved that the developed assay by HPLC method is a simple, rapid and reliable for the quantification of the mangiferin from M. indica . Abbreviations Used: M. indica : Mangifera indica , RP-HPLC: Reversed-phase high-performance liquid chromatography, M/Z: Mass to charge ratio, ICH: International conference on harmonization, % RSD: Percentage of relative standard deviation, ppm: Parts per million, LOD: Limit of detection, LOQ: Limit of quantification.

Trace analysis of three fungicides in animal origin foods with a modified QuEChERS method and liquid chromatography-tandem mass spectrometry.

PubMed

Mu, Zhaobin; Feng, Xiaoxiao; Zhang, Yun; Zhang, Hongyan

2016-02-01

A multi-residue method based on modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) sample preparation, followed by liquid chromatography tandem mass spectrometry (LC-MS/MS), was developed and validated for the determination of three selected fungicides (propiconazole, pyraclostrobin, and isopyrazam) in seven animal origin foods. The overall recoveries at the three spiking levels of 0.005, 0.05, and 0.5 mg kg(-1) spanned between 72.3 and 101.4% with relative standard deviation (RSD) values between 0.7 and 14.9%. The method shows good linearity in the concentrations between 0.001 and 1 mg L(-1) with the coefficient of determination (R (2)) value >0.99 for each target analyte. The limit of detections (LODs) for target analytes were between 0.04 and 1.26 μg kg(-1), and the limit of quantifications (LOQs) were between 0.13 and 4.20 μg kg(-1). The matrix effect for each individual compound was evaluated through the study of ratios of the areas obtained in solvent and matrix standards. The optimized method provided a negligible matrix effect for propiconazole within 20%, whereas for pyraclostrobin and isopyrazam, the matrix effect was relatively significant with a maximum value of 49.8%. The developed method has been successfully applied to the analysis of 210 animal origin samples obtained from 16 provinces of China. The results suggested that the developed method was satisfactory for trace analysis of three fungicides in animal origin foods.

Quantification of maltol in Korean ginseng (Panax ginseng) products by high-performance liquid chromatography-diode array detector

PubMed Central

Jeong, Hyun Cheol; Hong, Hee-Do; Kim, Young-Chan; Rhee, Young Kyoung; Choi, Sang Yoon; Kim, Kyung-Tack; Kim, Sung Soo; Lee, Young-Chul; Cho, Chang-Won

2015-01-01

Background: Maltol, as a type of phenolic compounds, is produced by the browning reaction during the high-temperature treatment of ginseng. Thus, maltol can be used as a marker for the quality control of various ginseng products manufactured by high-temperature treatment including red ginseng. For the quantification of maltol in Korean ginseng products, an effective high-performance liquid chromatography-diode array detector (HPLC-DAD) method was developed. Materials and Methods: The HPLC-DAD method for maltol quantification coupled with a liquid-liquid extraction (LLE) method was developed and validated in terms of linearity, precision, and accuracy. An HPLC separation was performed on a C18 column. Results: The LLE methods and HPLC running conditions for maltol quantification were optimized. The calibration curve of the maltol exhibited good linearity (R2 = 1.00). The limit of detection value of maltol was 0.26 μg/mL, and the limit of quantification value was 0.79 μg/mL. The relative standard deviations (RSDs) of the data of the intra- and inter-day experiments were <1.27% and 0.61%, respectively. The results of the recovery test were 101.35–101.75% with an RSD value of 0.21–1.65%. The developed method was applied successfully to quantify the maltol in three ginseng products manufactured by different methods. Conclusion: The results of validation demonstrated that the proposed HPLC-DAD method was useful for the quantification of maltol in various ginseng products. PMID:26246746

Comparison of two microextraction methods based on solidification of floating organic droplet for the determination of multiclass analytes in river water samples by liquid chromatography tandem mass spectrometry using Central Composite Design.

PubMed

Asati, Ankita; Satyanarayana, G N V; Patel, Devendra K

2017-09-01

Two low density organic solvents based liquid-liquid microextraction methods, namely Vortex assisted liquid-liquid microextraction based on solidification of floating organic droplet (VALLME-SFO) and Dispersive liquid-liquid microextraction based on solidification of floating organic droplet(DLLME-SFO) have been compared for the determination of multiclass analytes (pesticides, plasticizers, pharmaceuticals and personal care products) in river water samples by using liquid chromatography tandem mass spectrometry (LC-MS/MS). The effect of various experimental parameters on the efficiency of the two methods and their optimum values were studied with the aid of Central Composite Design (CCD) and Response Surface Methodology(RSM). Under optimal conditions, VALLME-SFO was validated in terms of limit of detection, limit of quantification, dynamic linearity range, determination of coefficient, enrichment factor and extraction recovery for which the respective values were (0.011-0.219ngmL -1 ), (0.035-0.723ngmL -1 ), (0.050-0.500ngmL -1 ), (R 2 =0.992-0.999), (40-56), (80-106%). However, when the DLLME-SFO method was validated under optimal conditions, the range of values of limit of detection, limit of quantification, dynamic linearity range, determination of coefficient, enrichment factor and extraction recovery were (0.025-0.377ngmL -1 ), (0.083-1.256ngmL -1 ), (0.100-1.000ngmL -1 ), (R 2 =0.990-0.999), (35-49), (69-98%) respectively. Interday and intraday precisions were calculated as percent relative standard deviation (%RSD) and the values were ≤15% for VALLME-SFO and DLLME-SFO methods. Both methods were successfully applied for determining multiclass analytes in river water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Expert diagnosis of plus disease in retinopathy of prematurity from computer-based image analysis

PubMed Central

Campbell, J. Peter; Ataer-Cansizoglu, Esra; Bolon-Canedo, Veronica; Bozkurt, Alican; Erdogmus, Deniz; Kalpathy-Cramer, Jayashree; Patel, Samir N.; Reynolds, James D.; Horowitz, Jason; Hutcheson, Kelly; Shapiro, Michael; Repka, Michael X.; Ferrone, Phillip; Drenser, Kimberly; Martinez-Castellanos, Maria Ana; Ostmo, Susan; Jonas, Karyn; Chan, R.V. Paul; Chiang, Michael F.

2016-01-01

Importance Published definitions of “plus disease” in retinopathy of prematurity (ROP) reference arterial tortuosity and venous dilation within the posterior pole based on a standard published photograph. One possible explanation for limited inter-expert reliability for plus disease diagnosis is that experts deviate from the published definitions. Objective To identify vascular features used by experts for diagnosis of plus disease through quantitative image analysis. Design We developed a computer-based image analysis system (Imaging and Informatics in ROP, i-ROP), and trained the system to classify images compared to a reference standard diagnosis (RSD). System performance was analyzed as a function of the field of view (circular crops 1–6 disc diameters [DD] radius) and vessel subtype (arteries only, veins only, or all vessels). The RSD was compared to the majority diagnosis of experts. Setting Routine ROP screening in neonatal intensive care units at 8 academic institutions. Participants A set of 77 digital fundus images was used to develop the i-ROP system. A subset of 73 images was independently classified by 11 ROP experts for validation. Main Outcome Measures The primary outcome measure was the percentage accuracy of i-ROP system classification of plus disease with the RSD as a function of field-of-view and vessel type. Secondary outcome measures included the accuracy of the 11 experts compared to the RSD. Results Accuracy of plus disease diagnosis by the i-ROP computer based system was highest (95%, confidence interval [CI] 94 – 95%) when it incorporated vascular tortuosity from both arteries and veins, and with the widest field of view (6 disc diameter radius). Accuracy was ≤90% when using only arterial tortuosity (P<0.001), and ≤85% using a 2–3 disc diameter view similar to the standard published photograph (p<0.001). Diagnostic accuracy of the i-ROP system (95%) was comparable to that of 11 expert clinicians (79–99%). Conclusions and Relevance ROP experts appear to consider findings from beyond the posterior retina when diagnosing plus disease, and consider tortuosity of both arteries and veins, in contrast to published definitions. It is feasible for a computer-based image analysis system to perform comparably to ROP experts, using manually segmented images. PMID:27077667

Expert Diagnosis of Plus Disease in Retinopathy of Prematurity From Computer-Based Image Analysis.

PubMed

Campbell, J Peter; Ataer-Cansizoglu, Esra; Bolon-Canedo, Veronica; Bozkurt, Alican; Erdogmus, Deniz; Kalpathy-Cramer, Jayashree; Patel, Samir N; Reynolds, James D; Horowitz, Jason; Hutcheson, Kelly; Shapiro, Michael; Repka, Michael X; Ferrone, Phillip; Drenser, Kimberly; Martinez-Castellanos, Maria Ana; Ostmo, Susan; Jonas, Karyn; Chan, R V Paul; Chiang, Michael F

2016-06-01

Published definitions of plus disease in retinopathy of prematurity (ROP) reference arterial tortuosity and venous dilation within the posterior pole based on a standard published photograph. One possible explanation for limited interexpert reliability for a diagnosis of plus disease is that experts deviate from the published definitions. To identify vascular features used by experts for diagnosis of plus disease through quantitative image analysis. A computer-based image analysis system (Imaging and Informatics in ROP [i-ROP]) was developed using a set of 77 digital fundus images, and the system was designed to classify images compared with a reference standard diagnosis (RSD). System performance was analyzed as a function of the field of view (circular crops with a radius of 1-6 disc diameters) and vessel subtype (arteries only, veins only, or all vessels). Routine ROP screening was conducted from June 29, 2011, to October 14, 2014, in neonatal intensive care units at 8 academic institutions, with a subset of 73 images independently classified by 11 ROP experts for validation. The RSD was compared with the majority diagnosis of experts. The primary outcome measure was the percentage of accuracy of the i-ROP system classification of plus disease, with the RSD as a function of the field of view and vessel type. Secondary outcome measures included the accuracy of the 11 experts compared with the RSD. Accuracy of plus disease diagnosis by the i-ROP computer-based system was highest (95%; 95% CI, 94%-95%) when it incorporated vascular tortuosity from both arteries and veins and with the widest field of view (6-disc diameter radius). Accuracy was 90% or less when using only arterial tortuosity and 85% or less using a 2- to 3-disc diameter view similar to the standard published photograph. Diagnostic accuracy of the i-ROP system (95%) was comparable to that of 11 expert physicians (mean 87%, range 79%-99%). Experts in ROP appear to consider findings from beyond the posterior retina when diagnosing plus disease and consider tortuosity of both arteries and veins, in contrast with published definitions. It is feasible for a computer-based image analysis system to perform comparably with ROP experts, using manually segmented images.

Comparison of the Characteristics and Performance of Flurbiprofen 8.75 mg Spray for Sore Throat.

PubMed

Veale, David; Shephard, Adrian; Adams, Verity; Lidster, Charlotte

2017-01-01

Sore throat sprays provide targeted relief by delivering the active ingredient directly to the site of pain. Different sprays vary in characteristics, thus affecting delivery of the active ingredient to the throat, which can impact compliance. The characteristics and performance of FLURBIPROFEN 8.75 mg SPRAY were compared with 12 other sprays. Parameters assessed included spray angle and pattern, droplet size distribution, shot weight uniformity and shot weight throughout life. Among all sprays tested WICK Sulagil Halsspray had the smallest spray angle (46°) and also the smallest diameter spray pattern (X=32.8 mm; Y=34.4 mm). Thiovalone® Buccal Spray Suspension had both the largest spray angle (82°) and largest diameter spray pattern (X=62.6 mm; Y=78.0 mm). Hasco Sept® Aerosol Spray had the smallest droplet size (Dv90=118.4 μm) whereas OKi infiammazione e dolore® 0.16% spray had the largest (Dv90=214.34 μm). In terms of shot weight uniformity, TANTUM® VERDE GOLA 0.25% spray showed the least variation (2% RSD) between shots and UNIBEN Aerosol Spray the most (23.4% RSD). Shot weight throughout life studies showed that FLURBIPROFEN 8.75 mg SPRAY had the least deviation from shot weight (1.77%) whereas OKi infiammazione e dolore® 0.16% spray deviated the most (44.9%). FLURBIPROFEN 8.75 mg SPRAY had the second smallest spray angle/pattern and droplet size distribution and also the least variation in shot weight. Different sore throat sprays vary in different attributes, affecting delivery of the active ingredient. FLURBIPROFEN 8.75 mg SPRAY performed well overall, ranking first among all sprays tested, and providing a dose which is targeted and uniformly delivered throughout the life of the bottle. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Sympathetic Release of Splenic Monocytes Promotes Recurring Anxiety Following Repeated Social Defeat.

PubMed

McKim, Daniel B; Patterson, Jenna M; Wohleb, Eric S; Jarrett, Brant L; Reader, Brenda F; Godbout, Jonathan P; Sheridan, John F

2016-05-15

Neuroinflammatory signaling may contribute to the pathophysiology of chronic anxiety disorders. Previous work showed that repeated social defeat (RSD) in mice promoted stress-sensitization that was characterized by the recurrence of anxiety following subthreshold stress 24 days after RSD. Furthermore, splenectomy following RSD prevented the recurrence of anxiety in stress-sensitized mice. We hypothesize that the spleen of RSD-exposed mice became a reservoir of primed monocytes that were released following neuroendocrine activation by subthreshold stress. Mice were subjected to subthreshold stress (i.e., single cycle of social defeat) 24 days after RSD, and immune and behavioral measures were taken. Subthreshold stress 24 days after RSD re-established anxiety-like behavior that was associated with egress of Ly6C(hi) monocytes from the spleen. Moreover, splenectomy before RSD blocked monocyte trafficking to the brain and prevented anxiety-like behavior following subthreshold stress. Splenectomy, however, had no effect on monocyte accumulation or anxiety when determined 14 hours after RSD. In addition, splenocytes cultured 24 days after RSD exhibited a primed inflammatory phenotype. Peripheral sympathetic inhibition before subthreshold stress blocked monocyte trafficking from the spleen to the brain and prevented the re-establishment of anxiety in RSD-sensitized mice. Last, β-adrenergic antagonism also prevented splenic monocyte egress after acute stress. The spleen served as a unique reservoir of primed monocytes that were readily released following sympathetic activation by subthreshold stress that promoted the re-establishment of anxiety. Collectively, the long-term storage of primed monocytes in the spleen may have a profound influence on recurring anxiety disorders. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Illumina MiSeq investigations on the changes of microbial community in the Fusarium oxysporum f.sp. cubense infected soil during and after reductive soil disinfestation.

PubMed

Huang, Xinqi; Liu, Liangliang; Wen, Teng; Zhu, Rui; Zhang, Jinbo; Cai, Zucong

2015-12-01

Although reductive soil disinfestation (RSD) is increasingly used for the control of soil-borne diseases, its impact on the soil microbial community during and after RSD remains poorly understood. MiSeq pyrosequencing, real-time PCR and denaturing gradient gel electrophoresis were performed to investigate the changes of microbial community in the Fusarium oxysporum f. sp. cubense (FOC) infected soil during RSD and at the simulative banana cultivation after RSD. The results showed that RSD significantly increased soil microbial populations and a different microbial community with the pathogenic soil was established after RSD. Specifically, the number of Firmicutes mainly containing Ruminococcus and Coprococcus followed by a small part of Clostridium which were the dominant bacterial genera significantly increased during RSD. In contrast, Symbiobacterium and Flavisolibacter were the dominant genera in the flooding soil. When the soils were recovered under aerobic condition, the relative abundances of the bacteria belonging to the phylum Bacteroidetes, Acidobacteria, Planctomycetes increased as alternatives to the reducing Firmicutes. For fungi, the population of F. oxysporum significantly decreased during RSD accompanied with the pH decline, which resulted in the significant decrease of relative abundance in the phylum Ascomycota. Alternatively, the relative abundances of some other fungal species increased, such as Chaetomium spp. and Penicillium spp. belonging to Ascomycota and the family Clavulinaceae belonging to Basidiomycota. Then, the relative abundance of Ascomycota re-increased after RSD with Podospora and Zopfiella as dominant genera, whereas the relative abundance of Fusarium further decreased. Overall, the microbial populations and community re-established by RSD made the soil more disease-suppressive and beneficial to the soil nutrient cycling and plant growth compared with the previous pathogenic soil. Copyright © 2015 Elsevier GmbH. All rights reserved.

Effects of renal sympathetic denervation on the atrial electrophysiology in dogs with pacing-induced heart failure.

PubMed

Wang, Xiaozhan; Zhao, Qingyan; Deng, Hongping; Wang, Xule; Guo, Zongwen; Dai, Zixuan; Xiao, Jinping; Wan, Peixing; Huang, Congxin

2014-10-01

Heart failure (HF) and atrial fibrillation (AF) are associated with sympathetic activation. Renal sympathetic denervation (RSD) can suppress AF vulnerability. The impact of RSD on atrial electrophysiology in experimental HF is unclear. Twenty-two beagles were randomized into control, HF, and HF + RSD groups. Control dogs were implanted cardiac pacemakers without pacing. Dogs in the HF group underwent right ventricular pacing for 3 weeks at 240 beats/min to induce HF. The dogs in the HF + RSD group received RSD and underwent the same HF-inducing procedure. The P-wave dispersion was higher in HF dogs than in the control and HF + RSD dogs (19 ± 3.1 ms vs 13 ± 2.3 ms, 15 ± 2.9 ms, P = 0.04). Conduction time within the interatrium was significantly longer in the HF dogs than that in the control and HF + RSD dogs (39 ± 4 ms vs 31 ± 3 ms, 33 ± 4 ms; P = 0.03). Window of vulnerability (WOV) of AF was widened in the HF dogs than in the HF + RSD dogs (37 ± 5 ms vs 14 ± 3 ms; P < 0.01), while AF could not be induced (WOV = 0) in the control dogs during S1 S2 stimulation. The voltage in the threshold for AF inducibility was lower during ganglionated plexi stimulation in the HF dogs than in the control and HF + RSD dogs (1.8 ± 0.6 V vs 2.5 ± 0.6 V, 2.4 ± 0.4 V; P = 0.04). RSD could reverse the atrial electrical remodeling and decrease AF inducibility in dogs with pacing-induced HF. ©2014 Wiley Periodicals, Inc.

Sympathetic Release of Splenic Monocytes Promotes Recurring Anxiety Following Repeated Social Defeat

PubMed Central

McKim, Daniel B.; Patterson, Jenna M.; Wohleb, Eric S.; Jarrett, Brant; Reader, Brenda; Godbout, Jonathan P.; Sheridan, John F.

2015-01-01

Background Neuroinflammatory signaling may contribute to the pathophysiology of chronic anxiety disorders. Previous work showed that repeated social defeat (RSD) in mice promoted stress-sensitization that was characterized by the recurrence of anxiety following sub-threshold stress 24 days after RSD. Furthermore, splenectomy following RSD prevented the recurrence of anxiety in stress-sensitized (SS) mice. We hypothesize that the spleen of RSD-exposed mice became a reservoir of primed monocytes that were released following neuroendocrine activation by sub-threshold stress. Methods Mice were subjected to sub-threshold stress (i.e., single cycle of social defeat) 24 days after RSD, and immune and behavioral measures were taken. Results Sub-threshold stress 24 days after RSD re-established anxiety-like behavior that was associated with egress of Ly6Chi monocytes from the spleen. Moreover, splenectomy prior to RSD blocked monocyte trafficking to the brain and prevented anxiety-like behavior following sub-threshold stress. Splenectomy, however, had no effect on monocyte accumulation or anxiety when determined 14 hours after RSD. In addition, splenocytes cultured 24 days after RSD exhibited a primed inflammatory phenotype. Peripheral sympathetic inhibition prior to sub-threshold stress blocked monocyte trafficking from the spleen to the brain and prevented the re-establishment of anxiety in RSD-sensitized mice. Last, β-adrenergic antagonism also prevented splenic monocyte egress after acute stress. Conclusion The spleen served as a unique reservoir of primed monocytes that were readily released following sympathetic activation by sub-threshold stress that promoted the re-establishment of anxiety. Collectively, the long-term storage of primed monocytes in the spleen may have a profound influence on recurring anxiety disorders. PMID:26281717

Application of a microplate-based ORAC-pyrogallol red assay for the estimation ofantioxidant capacity: First Action 2012.03.

PubMed

Ortiz, Rocío; Antilén, Mónica; Speisky, Hernán; Aliaga, Margarita E; López-Alarcón, Camilo; Baugh, Steve

2012-01-01

A method was developed for microplate-based oxygen radicals absorbance capacity (ORAC) using pyrogallol red (PGR) as probe (ORAC-PGR). The method was evaluated for linearity, precision, and accuracy. In addition, the antioxidant capacity of commercial beverages, such as wines, fruit juices, and iced teas, was measured. Linearity of the area under the curve (AUC) versus Trolox concentration plots was [AUC = (845 +/- 110) + (23 +/- 2) [Trolox, microM]; R = 0.9961, n = 19]. Analyses showed better precision and accuracy at the highest Trolox concentration (40 microM) with RSD and recovery (REC) values of 1.7 and 101.0%, respectively. The method also showed good linearity for red wine [AUC = (787 +/- 77) + (690 +/- 60) [red wine, microL/mL]; R = 0.9926, n = 17], precision and accuracy with RSD values from 1.4 to 8.3%, and REC values that ranged from 89.7 to 103.8%. Red wines showed higher ORAC-PGR values than white wines, while the ORAC-PGR index of fruit juices and iced teas presented a wide range of results, from 0.6 to 21.6 mM of Trolox equivalents. Product-to-product variability was also observed for juices of the same fruit, showing the differences between brands on the ORAC-PGR index.

Telltale Signs and Symptoms of CRPS/RSD

MedlinePlus

... Living With CRPS/RSD Symptoms of CRPS/RSD Definition of CRPS Diagnosed: Now What? Coping Strategies Caregivers CRPS Comfortable Clothing For Youth Stories of Hope Research/Medical Clinical Guidelines Treatments Educational Presentations RSDSA Videos Accredited Course ...

Spectroscopic study of the reaction mechanism of buspirone interaction with iodine and tetracyanoethylene reagents and its applications.

PubMed

Zayed, M A; El-Habeeb, Abeer A

2009-06-01

The reactions between the drug buspirone (busp) in its base form and iodine amphoteric reagent (n-donor and/or sigma-acceptor) and with tetracyanoethylene as a pi-acceptor reagent (TCNE) have been studied spectrophotometrically at different reactant concentrations, time intervals, temperatures, and with different solvents and wavelengths, with the aim of selecting the conditions that give the most suitable molar extinction coefficients. This study aims chiefly to throw light on the nature of these reactions and to select the most proper conditions for spectrophotometric application of these reagents to determine this biologically active drug used in treating different diseases. The reaction mechanism involves the formation of busp-I(2) outer and inner sphere complexes. The separated busp-I(2) solid product obtained was investigated using elemental analyses, FT-IR, thermal analyses (TA) and electron ionization mass spectrometry (EI-MS) and was found to be biologically active. The reaction mechanism of busp-TCNE involves the formation of a charge transfer (CT) complex. The analytical parameters of the proposed spectrophotometric procedures were calculated. These procedures were applied in the analysis of busp in its formulations as a drug used to treat psychiatric illnesses. The values of the Sandell sensitivity, standard deviation (SD), relative standard deviation (RSD) and recovery percentage show the high sensitivity of these procedures. This study also presents a promising new busp-I(2) drug derivative that can be used more efficiently for the same purposes as its parent. It gives a clear idea about the possible metabolites and metabolic pathways of busp and its derivative that may occur in vivo. Copyright 2009 John Wiley & Sons, Ltd.

Sequential determination of fat- and water-soluble vitamins in Rhodiola imbricata root from trans-Himalaya with rapid resolution liquid chromatography/tandem mass spectrometry.

PubMed

Tayade, Amol B; Dhar, Priyanka; Kumar, Jatinder; Sharma, Manu; Chaurasia, Om P; Srivastava, Ravi B

2013-07-30

A rapid method was developed to determine both types of vitamins in Rhodiola imbricata root for the accurate quantification of free vitamin forms. Rapid resolution liquid chromatography/tandem mass spectrometry (RRLC-MS/MS) with electrospray ionization (ESI) source operating in multiple reactions monitoring (MRM) mode was optimized for the sequential analysis of nine water-soluble vitamins (B1, B2, two B3 vitamins, B5, B6, B7, B9, and B12) and six fat-soluble vitamins (A, E, D2, D3, K1, and K2). Both types of vitamins were separated by ion-suppression reversed-phase liquid chromatography with gradient elution within 30 min and detected in positive ion mode. Deviations in the intra- and inter-day precision were always below 0.6% and 0.3% for recoveries and retention time. Intra- and inter-day relative standard deviation (RSD) values of retention time for water- and fat-soluble vitamin were ranged between 0.02-0.20% and 0.01-0.15%, respectively. The mean recoveries were ranged between 88.95 and 107.07%. Sensitivity and specificity of this method allowed the limits of detection (LOD) and limits of quantitation (LOQ) of the analytes at ppb levels. The linear range was achieved for fat- and water-soluble vitamins at 100-1000 ppb and 10-100 ppb. Vitamin B-complex and vitamin E were detected as the principle vitamins in the root of this adaptogen which would be of great interest to develop novel foods from the Indian trans-Himalaya. Copyright © 2013 Elsevier B.V. All rights reserved.

Long-term reproducibility of relative sensitivity factors obtained with CAMECA Wf

NASA Astrophysics Data System (ADS)

Gui, D.; Xing, Z. X.; Huang, Y. H.; Mo, Z. Q.; Hua, Y. N.; Zhao, S. P.; Cha, L. Z.

2008-12-01

As the wafer size continues to increase and the feature size of the integrated circuits (IC) continues to shrink, process control of IC manufacturing becomes ever more important to reduce the cost of failures caused by the drift of processes or equipments. Characterization tools with high precision and reproducibility are required to capture any abnormality of the process. Although Secondary ion mass spectrometry (SIMS) has been widely used in dopant profile control, it was reported that magnetic sector SIMS, compared to quadrupole SIMS, has lower short-term repeatability and long-term reproducibility due to the high extraction field applied between sample and extraction lens. In this paper, we demonstrate that CAMECA Wf can deliver high long-term reproducibility because of its high-level automation and improved design of immersion lens. The relative standard deviation (R.S.D.) of the relative sensitivity factors (RSF) of three typical elements, i.e., boron (B), phosphorous (P) and nitrogen (N), over 3 years are 3.7%, 5.5% and 4.1%, respectively. The high reproducibility results have a practical implication that deviation can be estimated without testing the standards.

Validation of a quantitative NMR method for suspected counterfeit products exemplified on determination of benzethonium chloride in grapefruit seed extracts.

PubMed

Bekiroglu, Somer; Myrberg, Olle; Ostman, Kristina; Ek, Marianne; Arvidsson, Torbjörn; Rundlöf, Torgny; Hakkarainen, Birgit

2008-08-05

A 1H-nuclear magnetic resonance (NMR) spectroscopy method for quantitative determination of benzethonium chloride (BTC) as a constituent of grapefruit seed extract was developed. The method was validated, assessing its specificity, linearity, range, and precision, as well as accuracy, limit of quantification and robustness. The method includes quantification using an internal reference standard, 1,3,5-trimethoxybenzene, and regarded as simple, rapid, and easy to implement. A commercial grapefruit seed extract was studied and the experiments were performed on spectrometers operating at two different fields, 300 and 600 MHz for proton frequencies, the former with a broad band (BB) probe and the latter equipped with both a BB probe and a CryoProbe. The concentration average for the product sample was 78.0, 77.8 and 78.4 mg/ml using the 300 BB probe, the 600MHz BB probe and CryoProbe, respectively. The standard deviation and relative standard deviation (R.S.D., in parenthesis) for the average concentrations was 0.2 (0.3%), 0.3 (0.4%) and 0.3mg/ml (0.4%), respectively.

Renal sympathetic denervation attenuates hypertension and vascular remodeling in renovascular hypertensive rats.

PubMed

Li, Peng; Huang, Pei-Pei; Yang, Yun; Liu, Chi; Lu, Yan; Wang, Fang; Sun, Wei; Kong, Xiang-Qing

2017-01-01

Li P, Huang P, Yang Y, Liu C, Lu Y, Wang F, Sun W, Kong X. Renal sympathetic denervation attenuates hypertension and vascular remodeling in renovascular hypertensive rats. J Appl Physiol 122: 121-129, 2017. First published October 14, 2016; doi:10.1152/japplphysiol.01019.2015-Sympathetic activity is enhanced in patients with essential or secondary hypertension, as well as in various hypertensive animal models. Therapeutic targeting of sympathetic activation is considered an effective antihypertensive strategy. We hypothesized that renal sympathetic denervation (RSD) attenuates hypertension and improves vascular remodeling and renal disease in the 2-kidney, 1-clip (2K1C) rat model. Rats underwent 2K1C modeling or sham surgery; then rats underwent RSD or sham surgery 4 wk later, thus resulting in four groups (normotensive-sham, normotensive-RSD, 2K1C-sham, and 2K1C-RSD). Norepinephrine was measured by ELISA. Echocardiography was used to assess heart function. Fibrosis and apoptosis were assessed by Masson and TUNEL staining. Changes in mean arterial blood pressure in response to hexamethonium and plasma norepinephrine levels were used to evaluate basal sympathetic nerve activity. The 2K1C modeling success rate was 86.8%. RSD reversed the elevated systolic blood pressure induced by 2K1C, but had no effect on body weight. Compared with rats in the 2K1C-sham group, rats in the 2K1C-RSD group showed lower left ventricular mass/body weight ratio, interventricular septal thickness in diastole, left ventricular end-systolic diameter, and left ventricular posterior wall thickness in systole, whereas fractional shortening and ejection fraction were higher. Right kidney apoptosis and left kidney hypertrophy were not changed by RSD. Arterial fibrosis was lower in animals in the 2K1C-RSD group compared with those in the 2K1C-sham group. RSD reduced plasma norepinephrine and basal sympathetic activity in rats in the 2K1C-RSD group compared with rats in the 2K1C-sham group. These results suggest a possible clinical efficacy of RSD for renovascular hypertension. The effects of renal sympathetic denervation (RSD) on hypertension, cardiac function, vascular fibrosis, and renal apoptosis were studied in the 2K1C rat model. Results showed that RSD attenuated hypertension, improved vascular remodeling, and reduced vascular fibrosis through decreased sympathetic activity in the 2K1C rat model, but it did not change the kidney size, renal apoptosis, or renal caspase-3 expression. These results could suggest possible clinical efficacy of RSD for renovascular hypertension. Copyright © 2017 the American Physiological Society.

Fast and high-efficiency magnetic surface imprinting based on microwave-accelerated reversible addition fragmentation chain transfer polymerization for the selective extraction of estrogen residues in milk.

PubMed

Chen, Fangfang; Wang, Jiayu; Lu, Ruicong; Chen, Huiru; Xie, Xiaoyu

2018-08-10

A novel microwave-accelerated reversible addition fragmentation chain transfer (RAFT) polymerization strategy has been introduced to shorten reaction time and improved polymerization efficiency of the conventional molecularly imprinting technology based on RAFT. Magnetic molecular imprinted polymers (MMIPs) were successfully synthesized much more efficiently using 17β-estradiol (E2) as a template for the determination of estrogen residues. The resultant MMIPs had well-defined thin imprinted film, favoring the fast mass transfer. Moreover, the reaction time, which was just 1/24 of the time taken by conventional heating, was significantly decreased, improving the reaction efficiency and reducing the probability of side reactions. Meanwhile, the obtained polymers have good capacity of 6.67 mg g -1 and satisfactory selectivity to template molecule with the imprinting factor of 5.11. As a result, a method combination of the resultant MMIPs as solid phase extraction sorbents and high-performance liquid chromatography was successfully set up to determinate three estrogen residues in milk samples. For E2, estrone, and estriol, the limit of detections were calculated to be 0.03, 0.08, and 0.06 ng mL -1 , respectively, and the limit of quantifications were 0.11, 0.27, and 0.21 ng mL -1 , respectively. At the spiked level of 1, 5, and 10 ng mL -1 , the recoveries of the three estrogens were ranged from 69.1% to 91.9% and the intra-day relative standard deviation (RSD) was less than 5.7%. In addition, the resultant MMIPs exhibited good reproducibility and reusability with the inter-batch RSD of 5.3% and the intra-batch RSD of 6.2%, respectively. Overall, the realization of this strategy facilitates the preparation of MMIPs with good architecture and high reaction efficiencies for the analysis of complicated real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Novel ion imprinted magnetic mesoporous silica for selective magnetic solid phase extraction of trace Cd followed by graphite furnace atomic absorption spectrometry detection

NASA Astrophysics Data System (ADS)

Zhao, Bingshan; He, Man; Chen, Beibei; Hu, Bin

2015-05-01

Determination of trace Cd in environmental, biological and food samples is of great significance to toxicological research and environmental pollution monitoring. While the direct determination of Cd in real-world samples is difficult due to its low concentration and the complex matrix. Herein, a novel Cd(II)-ion imprinted magnetic mesoporous silica (Cd(II)-II-MMS) was prepared and was employed as a selective magnetic solid-phase extraction (MSPE) material for extraction of trace Cd in real-world samples followed by graphite furnace atomic absorption spectrometry (GFAAS) detection. Under the optimized conditions, the detection limit of the proposed method was 6.1 ng L- 1 for Cd with the relative standard deviation (RSD) of 4.0% (c = 50 ng L- 1, n = 7), and the enrichment factor was 50-fold. To validate the proposed method, Certified Reference Materials of GSBZ 50009-88 environmental water, ZK018-1 lyophilized human urine and NIES10-b rice flour were analyzed and the determined values were in a good agreement with the certified values. The proposed method exhibited a robust anti-interference ability due to the good selectivity of Cd(II)-II-MMS toward Cd(II). It was successfully employed for the determination of trace Cd(II) in environmental water, human urine and rice samples with recoveries of 89.3-116%, demonstrating that the proposed method has good application potential in real world samples with complex matrix.

Determination of pesticide residues in samples of green minor crops by gas chromatography and ultra performance liquid chromatography coupled to tandem quadrupole mass spectrometry.

PubMed

Walorczyk, Stanisław; Drożdżyński, Dariusz; Kierzek, Roman

2015-01-01

A method was developed for pesticide analysis in samples of high chlorophyll content belonging to the group of minor crops. A new type of sorbent, known as ChloroFiltr, was employed for dispersive-solid phase extraction cleanup (dispersive-SPE) to reduce the unwanted matrix background prior to concurrent analysis by gas chromatography and ultra-performance liquid chromatography coupled to tandem quadrupole mass spectrometry (GC-MS/MS and UPLC-MS/MS). Validation experiments were carried out on green, unripe plants of lupin, white mustard and sorghum. The overall recoveries at the three spiking levels of 0.01, 0.05 and 0.5 mg kg(-1) fell in the range between 68 and 120% (98% on average) and 72-104% (93% on average) with relative standard deviation (RSD) values between 2 and 19% (7% on average) and 3-16% (6% on average) by GC-MS/MS and UPLC-MS/MS technique, respectively. Because of strong enhancement or suppression matrix effects (absolute values >20%) which were exhibited by about 80% of the pesticide and matrix combinations, acceptably accurate quantification was achieved by using matrix-matched standards. Up to now, the proposed method has been successfully used to study the dissipation patterns of pesticides after application on lupin, white mustard, soya bean, sunflower and field bean in experimental plot trials conducted in Poland. Copyright © 2014 Elsevier B.V. All rights reserved.

A highly selective and sensitive ultrasonic assisted dispersive liquid phase microextraction based on deep eutectic solvent for determination of cadmium in food and water samples prior to electrothermal atomic absorption spectrometry.

PubMed

Zounr, Rizwan Ali; Tuzen, Mustafa; Deligonul, Nihal; Khuhawar, Muhammad Yar

2018-07-01

A simple, fast, green, sensitive and selective ultrasonic assisted deep eutectic solvent liquid-phase microextraction technique was used for preconcentration and extraction of cadmium (Cd) in water and food samples by electrothermal atomic absorption spectrometry (ETAAS). In this technique, a synthesized reagent (Z)-N-(3,5-diphenyl-1H-pyrrol-2-yl)-3,5-diphenyl-2H-pyrrol-2-imine (Azo) was used as a complexing agent for Cd. The main factors effecting the pre-concentration and extraction of Cd such as effect of pH, type and composition of deep eutectic solvent (DES), volume of DES, volume of complexing agent, volume of tetrahydrofuran (THF) and ultrasonication time have been examined in detail. At optimum conditions the value of pH and molar ratio of DES were found to be 6.0 and 1:4 (ChCl:Ph), respectively. The detection limit (LOD), limit of quantification (LOQ), relative standard deviation (RSD) and preconcentration factor (PF) were observed as 0.023 ng L -1 , 0.161 ng L -1 , 3.1% and 100, correspondingly. Validation of the developed technique was observed by extraction of Cd in certified reference materials (CRMs) and observed results were successfully compared with certified values. The developed procedure was practiced to various food, beverage and water samples. Copyright © 2018 Elsevier Ltd. All rights reserved.

Determination of water-soluble vitamins in infant milk and dietary supplement using a liquid chromatography on-line coupled to a corona-charged aerosol detector.

PubMed

Márquez-Sillero, Isabel; Cárdenas, Soledad; Valcárcel, Miguel

2013-10-25

A simple and rapid method for the simultaneous determination of seven water-soluble vitamins (thiamine, folic acid, nicotinic acid, ascorbic acid, pantothenic acid, pyridoxine and biotin) was developed by high performance liquid chromatographic separation and corona-charged aerosol detection. The water-soluble vitamins were separated on a Lichrosorb RP-C18 column under isocratic conditions with a mobile phase consisting of 0.05 M ammonium acetate:methanol 90:10 (v/v) at the flow rate 0.5 mL min(-1). The vitamins were extracted from the infant milk (liquid and powder format) using a precipitation step with 2.5 M acetic acid remaining the analyte in the supernatant. As far as dietary supplements are concerned, only a dilution with distilled water was required. The detection limits ranged from 0.17 to 0.62 mg L(-1) for dietary supplements and 1.7 to 6.5 mg L(-1) for milk samples. The precision of the method was evaluated in terms of relative standard deviation (%, RSD) under repeatability and reproducibility conditions, being the average values for each parameter 2.6 and 2.7 for dietary supplements and 4.3 and 4.6 for milk samples. The optimized method was applied to different infant milk samples and dietary supplements. The results of the analysis were in good agreement with the declared values. Copyright © 2013 Elsevier B.V. All rights reserved.

Simultaneous determination of diclofenac and oxybuprocaine in human aqueous humor with HPLC and electrochemical detection.

PubMed

Kuhlmann, O; Stoldt, G; Struck, H G; Krauss, G J

1998-09-01

A sensitive and selective bioanalytical method for simultaneous determination of diclofenac and oxybuprocaine in human aqueous humor using reversed-phase HPLC and electrochemical detection is described. Chromatographic separation was achieved by using a Regis SPS 100 RP-8 column (5 microns; 150 x 4.6 mm I.D.). This support is coated with a hydrophilic polyoxyethylenepolymer. It allows protein-containing samples to be injected directly onto the column. The electrochemical detector permit a detection limit of 500 pg diclofenac per ml (daily relative standard deviation 6.3%) and 50 ng oxybuprocaine per ml (daily R.S.D. 2.6%), respectively. Results of administered and measured drug-concentrations in time dependent decrease are presented.

A dosimetric study of cardiac dose sparing using the reverse semi-decubitus technique for left breast and internal mammary chain irradiation.

PubMed

Niglas, Mark; McCann, Claire; Keller, Brian M; Makhani, Nadiya; Presutti, Joseph; Vesprini, Danny; Rakovitch, Eileen; Elzibak, Alyaa; Mashouf, Shahram; Lee, Justin

2016-01-01

Breath-hold techniques can reduce cardiac dose in breast radiotherapy. The reverse semi-decubitus (RSD) technique is an alternative free-breathing method used at our centre. This study compares the dosimetry of free-breathing supine, RSD and moderate deep inspiration breath-hold (mDIBH) techniques. Twelve patients with left-sided breast cancer who were simulated using standard supine, RSD and mDIBH techniques were identified retrospectively. New plans using standard breast tangents and techniques for internal mammary chain (IMC) nodal coverage were assessed. Using standard tangents, mean heart dose, heart V25Gy and mean left anterior descending artery (LAD) dose were found to be significantly lower for RSD and mDIBH when compared to free-breathing supine (p ⩽ 0.03). Using wide-tangents, the maximum LAD point dose was also lower for RSD and mDIBH (p ⩽ 0.02). There were no statistically significant dosimetric differences found between the RSD and mDIBH simulation techniques for standard breast-tangent plans, though organ-at-risk doses were lower for mDIBH in wide-tangent plans. There was no improvement in cardiac dosimetry between RSD and free-breathing supine when using an electron field IMC plan. For patients unable to tolerate breath-hold, the RSD technique is an alternative approach that can reduce cardiac dose. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Structural basis for the sequestration of the anti-σ(70) factor Rsd from σ(70) by the histidine-containing phosphocarrier protein HPr.

PubMed

Park, Young Ha; Um, Si Hyeon; Song, Saemee; Seok, Yeong Jae; Ha, Nam Chul

2015-10-01

Histidine-containing phosphocarrier protein (HPr) is a general component of the bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) involved in the phosphorylation-coupled transport of numerous sugars called PTS sugars. HPr mainly exists in a dephosphorylated form in the presence of PTS sugars in the medium, while its phosphorylation increases in the absence of PTS sugars. A recent study revealed that the dephosphorylated form of HPr binds and antagonizes the function of the antisigma factor Rsd. This anti-sigma factor sequesters the housekeeping sigma factor σ(70) to facilitate switching of the sigma subunit on RNA polymerase from σ(70) to the stress-responsive sigma factor σ(S) in stationary-phase cells. In this study, the structure of the complex of Rsd and HPr was determined at 2.1 Å resolution and revealed that the binding site for HPr on the surface of Rsd partly overlaps with that for σ(70). The localization of the phosphorylation site on HPr at the binding interface for Rsd explains why phosphorylation of HPr abolishes its binding to Rsd. The mutation of crucial residues involved in the HPr-Rsd interaction significantly influenced the competition between HPr and σ(70) for binding to Rsd both in vitro and in vivo. The results provide a structural basis for the linkage of global gene regulation to nutrient availability in the external environment.

Effect of renal sympathetic denervation on atrial substrate remodeling in ambulatory canines with prolonged atrial pacing.

PubMed

Wang, Xule; Zhao, Qingyan; Huang, He; Tang, Yanhong; Xiao, Jinping; Dai, Zixuan; Yu, Shengbo; Huang, Congxin

2013-01-01

We have previously demonstrated that catheter-based renal sympathetic denervation (RSD) could suppress atrial fibrillation (AF) in canines with short-time rapid right atrial pacing (RAP). However, the role of renal denervation on atrial remodeling is unclear. The aim of the present study was to explore the long-term effect of RSD on the atrial remodeling during prolonged RAP. Twenty mongrel dogs were implanted with a high-frequency cardiac pacemaker with a transvenous lead inserted into the right atrial appendage. The dogs were divided into three groups: a sham-operated group (n = 6), the chronic RAP (CRAP) group (n = 7), and the CRAP+RSD group (n = 7). In the CRAP+RSD group, a pacemaker was implanted 6 weeks after RSD was performed bilaterally for recovery. RAP was maintained for 5 weeks in CRAP group and CRAP+RSD group. The plasma levels of Angiotensin II and aldosterone were significantly increased in CRAP group compared with sham-operated group, but the increasing trend was inhibited in CRAP+RSD group compared with CRAP group (P<0.05). Similarly, RSD suppressed the increasing trend that prolonged RAP produced in the left atrial levels of ANP, TNF-α and IL-6. Compared with the sham-operated group, the CRAP group had significantly increased levels of caspase-3, bax and Cx40 whereas the level of Bcl-2 decreased (P<0.05). RSD markedly reduced the upregulation of caspase-3, bax and Cx40 and the downregulation of Bcl-2 expression compared with the CRAP group (P<0.05). Picric acid-sirius red staining study suggested that RSD could markedly alleviate the lesion degree of cardic fibrosis induced by CRAP (P<0.05). Immunohistochemistry results showed that the densities of TH- and GAP43- positive nerves were significantly elevated in the CRAP group compared with the sham-operated group, while RSD operation signicantly inhibited the these changes produced by CRAP. These findings suggest that renal denervation could suppress the atrial remodeling after prolonged RAP in ambulatory canines.

Effect of Renal Sympathetic Denervation on Atrial Substrate Remodeling in Ambulatory Canines with Prolonged Atrial Pacing

PubMed Central

Wang, Xule; Zhao, Qingyan; Huang, He; Tang, Yanhong; Xiao, Jinping; Dai, Zixuan; Yu, Shengbo; Huang, Congxin

2013-01-01

We have previously demonstrated that catheter-based renal sympathetic denervation (RSD) could suppress atrial fibrillation (AF) in canines with short-time rapid right atrial pacing (RAP). However, the role of renal denervation on atrial remodeling is unclear. The aim of the present study was to explore the long-term effect of RSD on the atrial remodeling during prolonged RAP. Twenty mongrel dogs were implanted with a high-frequency cardiac pacemaker with a transvenous lead inserted into the right atrial appendage. The dogs were divided into three groups: a sham-operated group (n = 6), the chronic RAP (CRAP) group (n = 7), and the CRAP+RSD group (n = 7). In the CRAP+RSD group, a pacemaker was implanted 6 weeks after RSD was performed bilaterally for recovery. RAP was maintained for 5 weeks in CRAP group and CRAP+RSD group. The plasma levels of Angiotensin II and aldosterone were significantly increased in CRAP group compared with sham-operated group, but the increasing trend was inhibited in CRAP+RSD group compared with CRAP group (P<0.05). Similarly, RSD suppressed the increasing trend that prolonged RAP produced in the left atrial levels of ANP, TNF-α and IL-6. Compared with the sham-operated group, the CRAP group had significantly increased levels of caspase-3, bax and Cx40 whereas the level of Bcl-2 decreased (P<0.05). RSD markedly reduced the upregulation of caspase-3, bax and Cx40 and the downregulation of Bcl-2 expression compared with the CRAP group (P<0.05). Picric acid–sirius red staining study suggested that RSD could markedly alleviate the lesion degree of cardic fibrosis induced by CRAP (P<0.05). Immunohistochemistry results showed that the densities of TH- and GAP43- positive nerves were significantly elevated in the CRAP group compared with the sham-operated group, while RSD operation signicantly inhibited the these changes produced by CRAP. These findings suggest that renal denervation could suppress the atrial remodeling after prolonged RAP in ambulatory canines. PMID:23724069

A simple sample preparation for simultaneous determination of chloramphenicol and its succinate esters in food products using high-performance liquid chromatography/high-resolution mass spectrometry.

PubMed

Amelin, Vasiliy; Korotkov, Anton

2017-02-01

A simple method is described for the determination of chloramphenicol and its succinate esters in food products. Examination of food products using high-performance liquid chromatography/high-resolution mass spectrometry showed the presence not only of chloramphenicol but also of its succinate forms. A scheme is proposed for determining chloramphenicol and its succinate esters (calculated as chloramphenicol) in meat (beef, pork, poultry), milk, liver, kidney, eggs, fish and honey. Analytes are extracted from a 1.0 g sample with 5 ml acetonitrile. It was found that using the method of standard addition and diluting the extract with water leads to the elimination of matrix effects and also eliminates errors associated with peak splitting due to the separate elution of the differing forms of the analyte. Validation results were satisfactory, with recoveries from 85% to 111% (meat, milk, liver, kidney, eggs, fish and honey) and a relative standard deviation (RSD) lower than 13% for spiked levels of 0.3, 1.0 and 5 µg kg - 1 . The limits of detection and quantification (calculated as chloramphenicol for all forms) were 0.1 and 0.3 µg kg - 1 , respectively. The RSD of the results of the analysis was < 10%. The duration of the analysis was less than 1 h.

pH-controlled quaternary ammonium herbicides capture/release by carboxymethyl-β-cyclodextrin functionalized magnetic adsorbents: Mechanisms and application.

PubMed

Liu, Chang; Wang, Peng; Shen, Zhigang; Liu, Xueke; Zhou, Zhiqiang; Liu, Donghui

2015-12-11

In our work, the pH-controlled magnetic solid phase extraction for the determination of paraquat and diquat was introduced firstly. Furthermore, to clarify the mechanism of carboxymethyl-β-cyclodextrin functionalized magnetic adsorbents, we studied the pH-responsive supramolecular interaction between carboxymethyl-β-cyclodextrin (CM-β-CD) and paraquat/diquat by ultraviolet-visible (UV-vis) spectroscopy and nuclear magnetic resonance (NMR) experiment, and the energy-minimized structures were also obtained. Then, the functional group CM-β-CD was modified on the surface of magnetic materials to synthesize the adsorbent. The Fourier transform infrared spectrum (FT-IR) results proved the successful modification of CM-β-CD. Thus, this absorbent was applied for the determination of paraquat and diquat in water. Under the optimal condition, limits of detection (LODs) of paraquat and diquat were 0.8 μg L(-1) and 0.9 μg L(-1), relative standard deviations (RSD) and recoveries varied 0.7-4.6% and 86.5-106.6%, respectively. Good recoveries (70.2-100.0%) and low RSD (1.7-9.6%) were achieved in analyzing spiked water samples. Furthermore, with the capillary electrophoresis (CE) as the analyser, the whole analytical process did not need the attendance of organic solvents. Copyright © 2015 Elsevier B.V. All rights reserved.

Rapid determination of nitrites in food using a diffuse UV-visible reflectance method.

PubMed

Khan, S; Vila, M M D C; Tubino, M

2012-08-01

A simple, low-cost, sensitive and selective method for the determination of trace quantities of nitrite in foods such as cheese and cured meat using diffuse ultraviolet-visible reflectance was developed. It is based on the reaction of nitrite with sulphadiazine and α-naphthol, which produces a coloured product in basic medium. The reaction is carried out directly in the measuring cell. For cheese the limit of detection (LOD), expressed as NaNO₂, was estimated to be about 2.0 × 10⁻²mg l⁻¹ (2.9 × 10⁻⁷mol l⁻¹) in the final measuring solution and 0.17 mg kg⁻¹ in cheese (2.5 × 10⁻⁶mol kg⁻¹). The relative standard deviation (RSD) varied from 5% to 8% depending on the sample. For meat the LOD was estimated to be about 2.0 × 10⁻²mg l⁻¹ (2.9 × 10⁻⁷mol l⁻¹) in the final measuring solution and 0.13 mg kg⁻¹ in meat (1.9 × 10⁻⁶mol kg⁻¹). The RSD varied from 3% to 6% depending on the sample. The results of the proposed method were also compared with those obtained with the official method using the statistical Student's t-test and F-test procedures.

A sensitive determination method for carbendazim and thiabendazole in apples by solid-phase microextraction-high performance liquid chromatography with fluorescence detection.

PubMed

Hu, Yanxue; Yang, Xiumin; Wang, Chun; Zhao, Jin; Li, Weining; Wang, Zhi

2008-03-01

A new analytical method for the determination of carbendazim (MBC) and thiabendazole (TBZ) in apples is reported, based on solid-phase microextraction (SPME) coupling HPLC with fluorescence detection. The main SPME and HPLC experimental conditions were optimized. The apples were first blended and centrifuged. Then, an aliquot of the resulting solution was subjected to SPME on a 60 microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre for 35 min at room temperature with the solution being stirred at 1100 rev min(-1). The extracted pesticides on the SPME fibre were desorbed in the mobile phase into the SPME/HPLC interface for HPLC analysis. The method was linear over the range 0.01-1 mg kg(-1) in apples for both MBC and TBZ, with detection limits of 0.005 and 0.003 mg kg(-1) and correlation coefficients of 0.9995 and 0.9998, respectively. The average recoveries for MBC and TBZ were 91.5 and 92.3% with the relative standard deviations (RSD) of 4.7 and 4.1% at the 0.1 mg kg(-1) level, and 94.6 and 96.1% with RSD of 3.3 and 3.8% at the 0.5 mg kg(-1) level, respectively. The method is simple, sensitive, organic solvent-free and is suitable for the determination of MBC and TBZ in apples.

A Novel Micellar Electrokinetic Chromatographic Method for Separation of Metal-DDTC Complexes

PubMed Central

Mallah, Arfana; Memon, Saima Q.; Solangi, Amber R.; Memon, Najma; Abbassi, Kulsoom; Khuhawar, Muhammad Yar

2012-01-01

Micellar electrokinetic chromatography (MEKC) was examined for the separation and determination of Mo(VI), Cr(VI), Ni(II), Pd(II), and Co(III) as diethyl dithiocarbamate (DDTC) chelates. The separation was achieved from fused silica capillary (52 cm × 75 μm id) with effective length 40 cm, background electrolyte (BGE) borate buffer pH 9.1 (25 mM), CTAB 30% (100 mM), and 1% butanol in methanol (70 : 30 : 5 v/v/v) with applied voltage of −10 kV using reverse polarity. The photodiode array detection was achieved at 225 nm. The linear calibration for each of the element was obtained within 0.16–10 μg/mL with a limit of detection (LOD) 0.005–0.0167 μg/mL. The separation and determination was repeatable with relative standard deviation (RSD) within 2.4–3.3% (n = 4) in terms of migration time and peak height/peak area. The method was applied for the determination of Mo(VI) from potatoes and almond, Ni(II) from hydrogenated vegetable oil, and Co(III) from pharmaceutical preparations with RSD within 3.9%. The results obtained were checked by standard addition and rechecked by atomic absorption spectrometry. PMID:22649320

Absolute Enumeration of Probiotic Strains Lactobacillus acidophilus NCFM® and Bifidobacterium animalis subsp. lactis Bl-04 ® via Chip-Based Digital PCR.

PubMed

Hansen, Sarah J Z; Morovic, Wesley; DeMeules, Martha; Stahl, Buffy; Sindelar, Connie W

2018-01-01

The current standard for enumeration of probiotics to obtain colony forming units by plate counts has several drawbacks: long time to results, high variability and the inability to discern between bacterial strains. Accurate probiotic cell counts are important to confirm the delivery of a clinically documented dose for its associated health benefits. A method is described using chip-based digital PCR (cdPCR) to enumerate Bifidobacterium animalis subsp. lactis Bl-04 and Lactobacillus acidophilus NCFM both as single strains and in combination. Primers and probes were designed to differentiate the target strains against other strains of the same species using known single copy, genetic differences. The assay was optimized to include propidium monoazide pre-treatment to prevent amplification of DNA associated with dead probiotic cells as well as liberation of DNA from cells with intact membranes using bead beating. The resulting assay was able to successfully enumerate each strain whether alone or in multiplex. The cdPCR method had a 4 and 5% relative standard deviation (RSD) for Bl-04 and NCFM, respectively, making it more precise than plate counts with an industry accepted RSD of 15%. cdPCR has the potential to replace traditional plate counts because of its precision, strain specificity and the ability to obtain results in a matter of hours.

Deep Eutectic Solvent-Based Microwave-Assisted Method for Extraction of Hydrophilic and Hydrophobic Components from Radix Salviae miltiorrhizae.

PubMed

Chen, Jue; Liu, Mengjun; Wang, Qi; Du, Huizhi; Zhang, Liwei

2016-10-17

Deep eutectic solvents (DESs) have attracted significant attention as a promising green media. In this work, twenty-five kinds of benign choline chloride-based DESs with microwave-assisted methods were applied to quickly extract active components from Radix Salviae miltiorrhizae . The extraction factors, including temperature, time, power of microwave, and solid/liquid ratio, were investigated systematically by response surface methodology. The hydrophilic and hydrophobic ingredients were extracted simultaneously under the optimized conditions: 20 vol% of water in choline chloride/1,2-propanediol (1:1, molar ratio) as solvent, microwave power of 800 W, temperature at 70 °C, time at 11.11 min, and solid/liquid ratio of 0.007 g·mL -1 . The extraction yield was comparable to, or even better than, conventional methods with organic solvents. The microstructure alteration of samples before and after extraction was also investigated. The method validation was tested as the linearity of analytes ( r ² > 0.9997 over two orders of magnitude), precision (intra-day relative standard deviation (RSD) < 2.49 and inter-day RSD < 2.96), and accuracy (recoveries ranging from 95.04% to 99.93%). The proposed DESs combined with the microwave-assisted method provided a prominent advantage for fast and efficient extraction of active components, and DESs could be extended as solvents to extract and analyze complex environmental and pharmaceutical samples.

SPME-Based Ca-History Method for Measuring SVOC Diffusion Coefficients in Clothing Material.

PubMed

Cao, Jianping; Liu, Ningrui; Zhang, Yinping

2017-08-15

Clothes play an important role in dermal exposure to indoor semivolatile organic compounds (SVOCs). The diffusion coefficient of SVOCs in clothing material (D m ) is essential for estimating SVOC sorption by clothing material and subsequent dermal exposure to SVOCs. However, few studies have reported the measured D m for clothing materials. In this paper, we present the solid-phase microextraction (SPME) based C a -history method. To the best of our knowledge, this is the first try to measure D m with known relative standard deviation (RSD). A thin sealed chamber is formed by a circular ring and two pieces of flat SVOC source materials that are tightly covered by the targeted clothing materials. D m is obtained by applying an SVOC mass transfer model in the chamber to the history of gas-phase SVOC concentrations (C a ) in the chamber measured by SPME. D m 's of three SVOCs, di-iso-butyl phthalate (DiBP), di-n-butyl phthalate (DnBP), and tris(1-chloro-2-propyl) phosphate (TCPP), in a cotton T-shirt can be obtained within 16 days, with RSD less than 3%. This study should prove useful for measuring SVOC D m in various sink materials. Further studies are expected to facilitate application of this method and investigate the effects of temperature, relative humidity, and clothing material on D m .

Identification and Quantification of Dimethylamylamine in Geranium by Liquid Chromatography Tandem Mass Spectrometry

PubMed Central

Li, J.S.; Chen, M.; Li, Z.C.

2012-01-01

A sensitive and reliable method of liquid chromatography–electrospray ionization/tandem mass spectrometry (LC-ESI/MS/ MS) was developed and validated for determining 1,3-dimethylamylamine (1,3-DMAA) and 1,4-dimethylamylamine (1,4-DMAA) in geranium plants (Pelargonium graveolens). The sample was extracted with 0.5 M HCl and purified by liquid-liquid partition with hexane. The parameters for reverse-phase (C18) LC and positive ESI/MS/MS were optimized. The matrix effect, specificity, linearity, precision, accuracy and reproducibility of the method were determined and evaluated. The method was linear over a range of 0.10–10.00 ng/mL examined, with R2 of 0.99 for both 1,3-DMAA and 1,4-DMAA. The recoveries from spiked concentrations between 5.00–40.00 ng/g were 85.1%–104.9% for 1,3-DMAA, with relative standard deviation (RSD) of 2.9%–11.0%, and 82.9%–101.8% for 1,4-DMAA, with RSD of 3.2%–11.7%. The instrument detection limit was 1–2 pg for both DMAAs. The quantification limit was estimated to be 1–2 ng/g for the plant sample. This method was successfully applied to the quantitative determination of 1,3- and 1,4-DMAA in both geranium plant and geranium oil. PMID:22915838

Simultaneous determination of multi drug components Theophylline, Etofylline, Guaiphenesine and Ambroxol Hydrochloride by validated RP-HPLC method in liquid dosage form.

PubMed

Jain, Jainendra Kumar; Prakash, M S; Mishra, Rajnish K; Khandhar, Amit P

2008-04-01

The RP-HPLC (reverse phase high performance liquid chromatography) method was developed and validated for simultaneous determination of Multi drug components i.e., Theophylline, Etofylline, Guaiphenesine and Ambroxol Hydrochloride in a liquid dosage form. Chromatographic separation of the four drugs was performed on a Hypersil Phenyl BDS (25cmX4.6mm, 5mm). The mobile phase constituted of triethylamine pH 3.0 buffer: methanol (85:15) v/v was delivered at the flow rate 1.5 mL/min. Detection was performed at 235 nm. The peak purity of Theophylline, Etofylline, Guaiphenesine and Ambroxol Hydrochloride were 0.99970, 0.99979, 0.99986 and 0.99949 respectively. Calibration curves were linear with correlation coefficient between 0.99995 to 0.99997 over a concentration range of 5 to 37 microg/mL for Theophylline, 19 to 140 microg/mL for Etofylline, 20 to 149 microg/mL for Guaiphenesine and 6 to 45 microg/mL for Ambroxol hydrochloride. The relative standard deviation (RSD) was found < 2.0%. The percentage recovery was found between the range of 98.6% and 100.5% at three different levels. Robustness and ruggedness were performed and result found within the RSD of 2%. All the parameters of validation were found in the acceptance range of ICH guideline.

Effect of renal sympathetic denervation on the progression of paroxysmal atrial fibrillation in canines with long-term intermittent atrial pacing.

PubMed

Wang, Xule; Huang, Congxin; Zhao, Qingyan; Huang, He; Tang, Yanhong; Dai, Zixuan; Wang, Xiaozhan; Guo, Zongwen; Xiao, Jinping

2015-04-01

The aim of the present study was to explore the effect of renal sympathetic denervation (RSD) on the progression of paroxysmal atrial fibrillation (AF) in canines with long-term intermittent atrial pacing. Nineteen beagles were randomly divided into sham-operated group (six dogs), control group (six dogs), and RSD group (seven dogs). Sham-operated group were implanted with pacemakers without pacing; control group were implanted with pacemakers with long-term intermittent atrial pacing; and RSD group underwent catheter-based RSD bilaterally and were simultaneously implanted with pacemakers. Atrial pacing was maintained for 8 h a day and a total of 12 weeks in the control group and RSD group. Echocardiography showed that the left atrial structure and function were significantly improved in the RSD group compared with the control group (P < 0.05). Compared with the control group, the RSD group had fewer incidences of AF and a shorter duration of AF (P < 0.05) after long-term intermittent atrial pacing. In addition to increased atrial effective refractory period (AERP) and AF cycle length, AERP dispersion and P-wave duration and dispersion were significantly decreased in the RSD group compared with the control group (P < 0.05). Atrial morphological evaluation suggested that fibrosis and ultrastructural changes induced by long-term intermittent atrial pacing were markedly suppressed in the RSD dogs compared with controls (P < 0.05). Immunohistochemistry results showed that connexin 43 distribution in RSD mid-myocardial was significantly fewer heterogeneous than that in control mid-myocardial (P < 0.05). Renal denervation inhibits the progression of paroxysmal AF, which might be related to the suppression of atrial electrophysiology and structural heterogeneity. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

Handgrip strength deficits best explain limitations in performing bimanual activities after stroke.

PubMed

Basílio, Marluce Lopes; de Faria-Fortini, Iza; Polese, Janaine Cunha; Scianni, Aline A; Faria, Christina Dcm; Teixeira-Salmela, Luci Fuscaldi

2016-04-01

[Purpose] To evaluate the relationships between residual strength deficits (RSD) of the upper limb muscles and the performance in bimanual activities and to determine which muscular group would best explain the performance in bimanual activities of chronic stroke individuals. [Subjects and Methods] Strength measures of handgrip, wrist extensor, elbow flexor/extensor, and shoulder flexor muscles of 107 subjects were obtained and expressed as RSD. The performance in bimanual activities was assessed by the ABILHAND questionnaire. [Results] The correlations between the RSD of handgrip and wrist extensor muscles with the ABILHAND scores were negative and moderate, whereas those with the elbow flexor/extensor and shoulder flexor muscles were negative and low. Regression analysis showed that the RSD of handgrip and wrist extensor muscles explained 38% of the variance in the ABILHAND scores. Handgrip RSD alone explained 33% of the variance. [Conclusion] The RSD of the upper limb muscles were negatively associated with the performance in bimanual activities and the RSD of handgrip muscles were the most relevant variable. It is possible that stroke subjects would benefit from interventions aiming at improving handgrip strength, when the goal is to increase the performance in bimanual activities.

Miniaturised electrically actuated high pressure injection valve for portable capillary liquid chromatography.

PubMed

Li, Yan; Pace, Kirsten; Nesterenko, Pavel N; Paull, Brett; Stanley, Roger; Macka, Mirek

2018-04-01

A miniaturised high pressure 6-port injection valve has been designed and evaluated for its performance in order to facilitate the development of portable capillary high performance liquid chromatography (HPLC). The electrically actuated valve features a very small size (65 × 19 × 19mm) and light weight (33g), and therefore can be easily integrated in a miniaturised modular capillary LC system suited for portable field analysis. The internal volume of the injection valve was determined as 98 nL. The novel conical shape of the stator and rotor and the spring-loaded rotor performed well up to 32MPa (4641psi), the maximum operating pressure investigated. Suitability for application was demonstrated using a miniaturised capillary LC system applied to the chromatographic separation of a mixture of biogenic amines and common cations. The RSD (relative standard deviation) values of retention times and peak areas of 6 successive runs were 0.5-0.7% and 1.8-2.8% for the separation of biogenic amines, respectively, and 0.1-0.2% and 2.1-3.0% for the separation of cations, respectively. This performance was comparable with bench-top HPLC systems thus demonstrating the applicability of the valve for use in portable and miniaturised capillary HPLC systems. Copyright © 2017 Elsevier B.V. All rights reserved.

Atmospherically Deposited PBDEs, Pesticides, PCBs, and PAHs in Western US National Park Fish: Concentrations and Consumption Guidelines

PubMed Central

Ackerman, Luke K.; Schwindt, Adam R.; Simonich, Staci L.; Koch, Dan C.; Blett, Tamara F.; Schreck, Carl B.; Kent, Michael L.; Landers, Dixon H.

2014-01-01

Concentrations of polybrominated diphenyl ethers (PBDEs), pesticides, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons were measured in 136 fish from 14 remote lakes in 8 western US National Parks/Preserves between 2003 and 2005 and compared to human and wildlife contaminant health thresholds. A sensitive (median detection limit −18 pg/g wet weight), efficient (61% recovery at 8 ng/g), reproducible (4.1 %RSD), and accurate (7 % deviation from SRM) analytical method was developed and validated for these analyses. Concentrations of PCBs, hexachlorobenzene, hexachlorocyclohexanes, DDTs and chlordanes in western US fish were comparable to or lower than mountain fish recently collected from Europe, Canada, and Asia. Dieldrin and PBDE concentrations were higher than recent measurements in mountain fish and Pacific Ocean salmon. Concentrations of most contaminants in western US fish were 1–6 orders of magnitude below calculated recreational fishing contaminant health thresholds. However, contaminant concentrations exceeded subsistence fishing cancer screening values in 8 of 14 lakes. Average contaminant concentrations in fish exceeded wildlife contaminant health thresholds for piscivorous mammals in 5 lakes, and piscivorous birds in all 14 lakes. These results indicate that atmospherically deposited organic contaminants can accumulate in high elevation fish, reaching concentrations relevant to human and wildlife health. PMID:18504962

Determination of Tangeretin in Rat Plasma: Assessment of Its Clearance and Absolute Oral Bioavailability.

PubMed

Elhennawy, Mai Gamal; Lin, Hai-Shu

2017-12-29

Tangeretin (TAN) is a dietary polymethoxylated flavone that possesses a broad scope of pharmacological activities. A simple high-performance liquid chromatography (HPLC) method was developed and validated in this study to quantify TAN in plasma of Sprague-Dawley rats. The lower limit of quantification (LLOQ) was 15 ng/mL; the intra- and inter-day assay variations expressed in the form of relative standard deviation (RSD) were all less than 10%; and the assay accuracy was within 100 ± 15%. Subsequently, pharmacokinetic profiles of TAN were explored and established. Upon single intravenous administration (10 mg/kg), TAN had rapid clearance ( Cl = 94.1 ± 20.2 mL/min/kg) and moderate terminal elimination half-life ( t 1/2 λz = 166 ± 42 min). When TAN was given as a suspension (50 mg/kg), poor but erratic absolute oral bioavailability (mean value < 3.05%) was observed; however, when TAN was given in a solution prepared with randomly methylated-β-cyclodextrin (50 mg/kg), its plasma exposure was at least doubled (mean bioavailability: 6.02%). It was obvious that aqueous solubility hindered the oral absorption of TAN and acted as a barrier to its oral bioavailability. This study will facilitate further investigations on the medicinal potentials of TAN.

Rapid column heating method for subcritical water chromatography.

PubMed

Fogwill, Michael O; Thurbide, Kevin B

2007-01-19

A novel resistive heating method is presented for subcritical water chromatography (SWC) that provides higher column heating rates than those conventionally obtained from temperature-programmed gas chromatography (GC) convection ovens. Since the polarity of water reduces dramatically with increasing temperature, SWC employs column heating to achieve gradient elution. As such, the rate at which the mobile phase is heated directly impacts the magnitude of such gradients applied in SWC. Data from the current study demonstrate that the maximum column heating rate attainable in a typical SWC apparatus (i.e. using a GC convection oven) is around 10 degrees C/min, even at instrument oven settings of over three times this value. Conversely, by wrapping the separation column with ceramic insulation and a resistively heated wire, the column heating rates are increased five-fold. As a result, elution times can be greatly decreased in SWC employing gradients. Separations of standard alcohol test mixtures demonstrate that the retention time of the latest eluting component decreases by 35 to 50% using the prototype method. Additionally, solute retention times in this mode deviate by less than 1% RSD over several trials, which compares very well to those obtained using a conventional GC convection oven. Results suggest that the developed method can be a useful alternative heating technique in SWC.

Extraction and analysis methods for the determination of pyrethroid insecticides in surface water, sediments and biological tissues at environmentally relevant concentrations.

PubMed

Mekebri, A; Crane, D B; Blondina, G J; Oros, D R; Rocca, J L

2008-05-01

The aim of this study was to develop and validate chemical methods for measuring pyrethroid insecticides at environmentally relevant concentrations in different matrices. The analytes included six synthetic pyrethroids with the highest agricultural and commercial structural uses in California: bifenthrin, cyfluthrin, cypermethrin, esfenvalerate/fenvalerate, lambda-cyhalothrin, permethrin, and their corresponding stereoisomers, which includes enantiomers, diastereomers and racemic mixtures. Fortified water samples were extracted for analysis of synthetic pyrethroids using liquid-liquid extraction, while fortified sediment and fish tissue samples were extracted using pressurized fluid extraction followed by gel permeation chromatography (GPC) to remove matrix interferences. A florisil column was used for additional cleanup and fractionation of sediment and tissue extracts. Extracts were analyzed using dual column high resolution gas chromatography with electron capture detection (GC/ECD) and confirmation was obtained with gas chromatography mass spectrometry using a quadrupole ion trap detector in MS-MS mode. Method detection limits (MDLs) have been established for water (1-3 ng/L), sediment (0.5-4 ng/g dry weight) and tissue (1-3 ng/g fresh weight). Mean percent recoveries of fortified blanks and samples ranged from 75 to 115% with relative standard deviation (RSD) values less than 20% for all target compounds.

A multisyringe flow-based system for kinetic-catalytic determination of cobalt(II).

PubMed

Chaparro, Laura; Ferrer, Laura; Leal, Luz; Cerdà, Víctor

2015-02-01

A kinetic-catalytic method for cobalt determination based on the catalytic effect of cobalt(II) on the oxidative coupling of 1,2-dihydroxyanthraquinone (alizarin) was automated exploiting multisyringe flow injection analysis (MSFIA). The proposed method was performed at pH 9.2, resulting in a discoloration process in the presence of hydrogen peroxide. The fixed-time approach was employed for analytical signal measurement. The spectrophotometric detection was used exploiting a liquid waveguide capillary cell (LWCC), of 1m optical length at 465 nm. The optimization was carried out by a multivariate approach, reaching critical values of 124 µmol L(-1) and 0.22 mol L(-1) for alizarin and hydrogen peroxide, respectively, and 67°C of reagent temperature. A sample volume of 150 µL was used allowing a sampling rate of 30h(-1). Under optimal conditions, calibration curve was linear in the range of 1-200 µg L(-1) Co, achieving a DL of 0.3 µg L(-1) Co. The repeatability, expressed as relative standard deviation (RSD) was lower than 1%. The proposed analytical procedure was applied to the determination of cobalt in cobalt gluconate and different forms of vitamin B12, cyanocobalamin and hydroxicobalamin with successful results showing recoveries around 95%. Copyright © 2014 Elsevier B.V. All rights reserved.

Preconcentration and speciation of ultra-trace Se (IV) and Se (VI) in environmental water samples with nano-sized TiO2 colloid and determination by HG-AFS.

PubMed

Fu, Jiaqi; Zhang, Xu; Qian, Shahua; Zhang, Lin

2012-05-30

A united method for speciation analysis of Se (IV) and Se (VI) in environmental water samples was developed using nano-sized TiO(2) colloid as adsorbent and hydride generation atomic fluorescence spectrometry (HG-AFS) as determination means. When the pH values of bulk solution were between 6.0 and 7.0, successful adsorption onto 1 mL nano-sized TiO(2) colloid (0.2%) was achieved for more than 97.0% of Se (IV) while Se (VI) barely got adsorbed. Therefore, the method made it possible to preconcentrate and determine Se (IV) and Se (VI) separately. The precipitated TiO(2) with concentrated selenium was directly converted to colloid without desorption. Selenium in the resulting colloid was then determined by HG-AFS. The detection limits (3σ) and relative standard deviations (R.S.D) of this method were 24 ng/L and 42 ng/L, 7.8% (n=6) and 7.0% (n=6) for Se (IV) and Se (VI), respectively. This simple, sensitive, and united method was successfully applied to the separation and speciation of ultra-trace Se (IV) and Se (VI) in environmental water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

[Analysis of methylmercury in biological guano by the optimized atomic fluorescence spectrometry coupled with microwave assisted extraction].

PubMed

Chen, Qian-Qian; Liu, Xiao-Dong; Sun, Li-Guang; Jiang, Shan; Yan, Hong; Liu, Yi; Luo, Yu-Han; Huang, Jing

2011-01-01

The analytical method for the determination of methylmercury in seabird excrements was established using atomic fluorescence spectrometry coupled with microwave-assisted extraction In general, temperature and hydrochloric amount are the most important influencing factors on the extraction of MeHg in the samples, and the present paper optimized these two parameters. The result showed that 120 degrees C and 200 microL 6 mol x L(-1) hydrochloric acid are the best extraction conditions. Under these experimental conditions, the relative standard deviation (RSD) values of reduplicative analyses on standard reference material (human hair powder) and the same seabird excrement sample were 0.74% and 6.61% respectively, and their percent recoveries were over 90%. The combination of microwave-assisted extraction and atomic fluorescence spectrometry has many advantages such as simple operation, high sensitivity, low detection limit and low cost, therefore, it is suitable for rapid separation and analysis of trace methylmercury composition in the biological guanos. Using this method, we analyzed the methylmercury contents in the ancient and fresh seabird droppings taken from Xisha Islands of South China Sea, and the result showed that the Xisha guanos were rich in methylmercury and the large input of seabird guanos will cause serious environmental contamination in the remote island ecosystem of Xisha Islands.

Aluminium sensitized spectrofluorimetric determination of fluoroquinolones in milk samples coupled with salting-out assisted liquid-liquid ultrasonic extraction

NASA Astrophysics Data System (ADS)

Xia, Qinghai; Yang, Yaling; Liu, Mousheng

2012-10-01

An aluminium sensitized spectrofluorimetric method coupled with salting-out assisted liquid-liquid ultrasonic extraction for the determination of four widely used fluoroquinolones (FQs) namely norfloxacin (NOR), ofloxacin (OFL), ciprofloxacin (CIP) and gatifloxacin (GAT) in bovine raw milk was described. The analytical procedure involves the fluorescence sensitization of aluminium (Al3+) by complexation with FQs, salting-out assisted liquid-liquid ultrasonic extraction (SALLUE), followed by spectrofluorometry. The influence of several parameters on the extraction (the salt species, the amount of salt, pH, temperature and phase volume ratio) was investigated. Under optimized experimental conditions, the detection limits of the method in milk varied from 0.009 μg/mL for NOR to 0.016 μg/mL for GAT (signal-to-noise ratio (S/N) = 3). The relative standard deviations (RSD) values were found to be relatively low (0.54-2.48% for four compounds). The calibration graph was linear from 0.015 to 2.25 μg/mL with coefficient of determinations not less than 0.9974. The methodology developed was applied to the determination of FQs in bovine raw milk samples. The main advantage of this method is simple, accurate and green. The method showed promising applications for analyzing polar analytes especially polar drugs in various sample matrices.

Ionic liquid based vortex assisted liquid-liquid microextraction combined with liquid chromatography mass spectrometry for the determination of bisphenols in thermal papers with the aid of response surface methodology.

PubMed

Asati, Ankita; Satyanarayana, G N V; Panchal, Smita; Thakur, Ravindra Singh; Ansari, Nasreen G; Patel, Devendra K

2017-08-04

A sensitive, rapid and efficient ionic liquid-based vortex assisted liquid-liquid microextraction (IL-VALLME) with Liquid Chromatography Mass spectrometry (LC-MS/MS) method is proposed for the determination of bisphenols in thermal paper. Extraction factors were systematically optimized by response surface methodology. Experimental factors showing significant effects on the analytical responses were evaluated using design of experiment. The limit of detection for Bisphenol-A (BPA) and Bisphenol-S (BPS) in thermal paper were 1.25 and 0.93μgkg -1 respectively. The dynamic linearity range for BPA was between 4 and 100μgkg -1 and the determination of coefficient (R 2 ) was 0.996. The values of the same parameters were 3-100μgkg -1 and 0.998 for BPS. The extraction recoveries of BPA and BPS in thermal paper were 101% and 99%. Percent relative standard deviation (% RSD) for matrix effect and matrix match effects were not more than 10%, for both bisphenols. The proposed method uses a statistical approach for the analysis of bisphenols in environmental samples, and is easy, rapid, requires minimum organic solvents and efficient. Copyright © 2017 Elsevier B.V. All rights reserved.

Development of a LC-MS method for simultaneous determination of amoxicillin and metronidazole in human serum using hydrophilic interaction chromatography (HILIC).

PubMed

Kathriarachchi, Udani L; Vidhate, Sagar S; Al-Tannak, Naser; Thomson, Alison H; da Silva Neto, Michael J J; Watson, David G

2018-07-01

A method was developed for the determination of amoxicillin and metronidazole in human serum. The procedure used was hydrophilic interaction chromatography (HILIC) followed by mass spectrometric (MS) detection. Chromatographic separation was achieved on a ZIC-HILIC column and the mobile phase consisted of a mixture of 0.1% (v/v) formic acid in water and 0.1% (v/v) formic acid in acetonitrile. The method was validated with regard to selectivity, accuracy, precision, calibration, lower limit of quantification (LOQ), extraction recovery and matrix effect. The LOQs were 0.0138 and 0.008 μg/ml for amoxicillin and metronidazole respectively, while for quantification purposes linearity was achieved in the range of 0.1 μg/ml to 6.4 μg/ml for both drugs with correlation coefficients >0.9990. The intraday precision (expressed as %RSD) and the accuracy (expressed as the % deviation from the nominal value) was <15% for both antibiotics at all QC levels. Extraction recoveries for both drugs and internal standards were >80%, while a considerable matrix effect (<60%) was observed for amoxicillin. Finally, the method was applied to the determination of amoxicillin and metronidazole concentrations in serum for 20 patients. Copyright © 2018 Elsevier B.V. All rights reserved.

Quantitative Analysis of Therapeutic Drugs in Dried Blood Spot Samples by Paper Spray Mass Spectrometry: An Avenue to Therapeutic Drug Monitoring

NASA Astrophysics Data System (ADS)

Manicke, Nicholas Edward; Abu-Rabie, Paul; Spooner, Neil; Ouyang, Zheng; Cooks, R. Graham

2011-09-01

A method is presented for the direct quantitative analysis of therapeutic drugs from dried blood spot samples by mass spectrometry. The method, paper spray mass spectrometry, generates gas phase ions directly from the blood card paper used to store dried blood samples without the need for complex sample preparation and separation; the entire time for preparation and analysis of blood samples is around 30 s. Limits of detection were investigated for a chemically diverse set of some 15 therapeutic drugs; hydrophobic and weakly basic drugs, such as sunitinib, citalopram, and verapamil, were found to be routinely detectable at approximately 1 ng/mL. Samples were prepared by addition of the drug to whole blood. Drug concentrations were measured quantitatively over several orders of magnitude, with accuracies within 10% of the expected value and relative standard deviation (RSD) of around 10% by prespotting an internal standard solution onto the paper prior to application of the blood sample. We have demonstrated that paper spray mass spectrometry can be used to quantitatively measure drug concentrations over the entire therapeutic range for a wide variety of drugs. The high quality analytical data obtained indicate that the technique may be a viable option for therapeutic drug monitoring.

Simple and Rapid Quantitative Determination of Thiol-Containing Toxicants Using Silver Nanoparticles as an Affinity Probe

NASA Astrophysics Data System (ADS)

Sharma, A.; Tapadia, K.

2017-01-01

A rapid and low-cost nano-drop spectrophotometric method using citrate-modified silver nanoparticles (Ag NPs) for the determination of thiol-containing toxicants was developed. The introduction of thioglycolic acid (TGA) and thiourea (TU) reduced the overall surface charge of Ag NPs, resulting in aggregation of Ag NPs, and a colorimetric response that was individually correlated with the concentration of TGA and TU. Under optimum experimental conditions, the maximum molar absorptivity values for TGA and TU were 1.04 × 105 and 2.13 × 105 L × mol-1 × cm-1, respectively, at λmax of 415 nm. The linear range used was 0.5-2.5 mg/L for TGA, and 0.3-1.5 mg/L for TU. The detection limits (3S) and % relative standard deviation (RSD) for the method were found to be 3 ppb, 2 ppb, and ±1.13%, ±0.96% for TGA and TU, respectively. This new chromogenic method provided a facile and sensitive scheme for the determination of TGA and TU, and could be applied for the determination of thiol-containing biomolecules. This scheme was tested for the analysis of real samples such as urine, blood, and environmental samples.

Determination of mercury in agroindustrial samples by flow-injection cold vapor atomic absorption spectrometry using ion exchange and reductive elution.

PubMed

Gomes Neto, J A; Zara, L F; Rocha, J C; Santos, A; Dakuzaku, C S; Nóbrega, J A

2000-03-06

A flow-injection system with a Chelite-S(R) cationic resin packed minicolumn is proposed for the determination of trace levels of mercury in agroindustrial samples by cold vapor atomic absorption spectrometry. Improved sensitivity and selectivity are attained since mercuric ions are on-line concentrated whereas other potential interferents are discarded. With on-line reductive elution procedure, concentrated hydrochloric acid could be replaced by 10% w/v SnCl(2), in 6 M HCl as eluent. The reversed-intermittent stream either carries the atomic mercury to the flow cell in the forward direction or removes the residue from reactor/gas-liquid separator to a discarding flask in the opposite direction. Concentration and volume of reagent, acidity, flow rates, commutation times and potential interfering species were investigated. For 120 s preconcentration time, the proposed system handles about 25 samples h(-1) (50.0-500 ng l(-1)), consuming about 10 ml sample and 5 mg SnCl(2) per determination. The detection limit is 0.8 ng l(-1) and the relative standard deviation (RSD) (n=12) of a 76.7 ng l(-1) sample is about 5%. Results are in agreement with certified value of standard materials at 95% confidence level and good recoveries (97-128%) of spiked samples were found.

Rapid analysis of caffeine in various coffee samples employing direct analysis in real-time ionization-high-resolution mass spectrometry.

PubMed

Danhelova, Hana; Hradecky, Jaromir; Prinosilova, Sarka; Cajka, Tomas; Riddellova, Katerina; Vaclavik, Lukas; Hajslova, Jana

2012-07-01

The development and use of a fast method employing a direct analysis in real time (DART) ion source coupled to high-resolution time-of-flight mass spectrometry (TOFMS) for the quantitative analysis of caffeine in various coffee samples has been demonstrated in this study. A simple sample extraction procedure employing hot water was followed by direct, high-throughput (<1 min per run) examination of the extracts spread on a glass rod under optimized conditions of ambient mass spectrometry, without any prior chromatographic separation. For quantification of caffeine using DART-TOFMS, an external calibration was used. Isotopically labeled caffeine was used to compensate for the variations of the ion intensities of caffeine signal. Recoveries of the DART-TOFMS method were 97% for instant coffee at the spiking levels of 20 and 60 mg/g, respectively, while for roasted ground coffee, the obtained values were 106% and 107% at the spiking levels of 10 and 30 mg/g, respectively. The repeatability of the whole analytical procedure (expressed as relative standard deviation, RSD, %) was <5% for all tested spiking levels and matrices. Since the linearity range of the method was relatively narrow (two orders of magnitude), an optimization of sample dilution prior the DART-TOFMS measurement to avoid saturation of the detector was needed.

Validation and Uncertainty Estimation of an Ecofriendly and Stability-Indicating HPLC Method for Determination of Diltiazem in Pharmaceutical Preparations

PubMed Central

Sadeghi, Fahimeh; Navidpour, Latifeh; Bayat, Sima; Afshar, Minoo

2013-01-01

A green, simple, and stability-indicating RP-HPLC method was developed for the determination of diltiazem in topical preparations. The separation was based on a C18 analytical column using a mobile phase consisted of ethanol: phosphoric acid solution (pH = 2.5) (35 : 65, v/v). Column temperature was set at 50°C and quantitation was achieved with UV detection at 240 nm. In forced degradation studies, the drug was subjected to oxidation, hydrolysis, photolysis, and heat. The method was validated for specificity, selectivity, linearity, precision, accuracy, and robustness. The applied procedure was found to be linear in diltiazem concentration range of 0.5–50 μg/mL (r 2 = 0.9996). Precision was evaluated by replicate analysis in which % relative standard deviation (RSD) values for areas were found below 2.0. The recoveries obtained (99.25%–101.66%) ensured the accuracy of the developed method. The degradation products as well as the pharmaceutical excipients were well resolved from the pure drug. The expanded uncertainty (5.63%) of the method was also estimated from method validation data. Accordingly, the proposed validated and sustainable procedure was proved to be suitable for routine analyzing and stability studies of diltiazem in pharmaceutical preparations. PMID:24163778

Renal sympathetic denervation improves rate control in patients with symptomatic persistent atrial fibrillation and hypertension.

PubMed

Qiu, Min; Shan, Qijun; Chen, Chun; Geng, Jie; Guo, Jiqun; Zhou, Xiujuan; Qian, Weichong; Tang, Lijun; Yin, Yuehui

2016-02-01

The aim of this study was to investigate whether renal sympathetic denervation (RSD) improves ventricular heart rate (HR) control in patients with persistent atrial fibrillation (AF). Twenty-one patients (aged 57.5 ± 10.2 years, 76.2% male) with persistent AF and hypertension underwent RSD and completed 7-days follow-up evaluations, including 24-hour Holter monitoring (Holter), blood pressure (BP), 24-hour ambulatory BP monitoring (ABPM). Patients were grouped into tertiles of average HR at baseline Holter recording for evaluation of RSD effects on atrioventricular (AV) node (group 1: HR ≧ 90 bpm; group 2: 80 bpm ≦ HR < 90 bpm; group 3: HR < 80 bpm). All patients successfully underwent RSD without any complications. The clinical and procedural characteristics were similar in all groups of patients. No significant changes in BP were observed in the three groups before and after RSD. Compared with baseline, the average HR (Holter) of patients in group 1, 2 and 3 had a reduction of 22.6 ± 13.2 bpm (83.3 ± 4.9 vs 106.0 ± 14.6, P = 0.004), 9.7 ± 7.8 bpm (75.7 ± 7.6 vs 85.4 ± 3.7, P = 0.017) and 2.3 ± 2.9 bpm (71.4 ± 4.0 vs 73.7 ± 4.7, P = 0.089) at 7 days after RSD, respectively. RSD could improve ventricular HR control in patients with persistent AF. RSD slowed AV node conduction in baseline HR-dependent manner. RSD may become an alternative non-pharmaceutical tool for rate control in patients with persistent AF.

Re-establishment of Anxiety in Stress-Sensitized Mice Is Caused by Monocyte Trafficking from the Spleen to the Brain

PubMed Central

Wohleb, Eric S.; McKim, Daniel B.; Shea, Daniel T.; Powell, Nicole D.; Tarr, Andrew J.; Sheridan, John F.; Godbout, Jonathan P.

2014-01-01

Background Persistent anxiety-like symptoms may have an inflammatory-related pathophysiology. Our previous work using repeated social defeat (RSD) in mice showed that recruitment of peripheral myeloid cells to the brain is required for the development of anxiety. Here, we aimed to determine if 1) RSD promotes prolonged anxiety through redistribution of myeloid cells and 2) prior exposure to RSD sensitizes the neuroimmune axis to secondary subthreshold stress. Methods Mice were subjected to RSD and several immune and behavioral parameters were determined 0.5, 8, or 24 days later. In follow-up studies, control and RSD mice were subjected to subthreshold stress at 24 days. Results Repeated social defeat-induced macrophage recruitment to the brain corresponded with development and maintenance of anxiety-like behavior 8 days after RSD, but neither remained at 24 days. Nonetheless, social avoidance and an elevated neuroinflammatory profile were maintained at 24 days. Subthreshold social defeat in RSD-sensitized mice increased peripheral macrophage trafficking to the brain that promoted re-establishment of anxiety. Moreover, subthreshold social defeat increased social avoidance in RSD-sensitized mice compared with naïve mice. Stress-induced monocyte trafficking was linked to redistribution of myeloid progenitor cells in the spleen. Splenectomy before subthreshold stress attenuated macrophage recruitment to the brain and prevented anxiety-like behavior in RSD-sensitized mice. Conclusions These data indicate that monocyte trafficking from the spleen to the brain contributes re-establishment of anxiety in stress-sensitized mice. These findings show that neuroinflammatory mechanisms promote mood disturbances following stress-sensitization and outline novel neuroimmune interactions that underlie recurring anxiety disorders such as posttraumatic stress disorder. PMID:24439304

Pulmonary vein isolation alone and combined with renal sympathetic denervation in chronic kidney disease patients with refractory atrial fibrillation.

PubMed

Kiuchi, Márcio G; Chen, Shaojie; E Silva, Gustavo R; Paz, Luis M R; Kiuchi, Tetsuaki; de Paula Filho, Ary G; Souto, Gladyston L L

2016-12-01

Atrial fibrillation (AF) commonly occurs in association with chronic kidney disease (CKD), resulting in adverse outcomes. Combining pulmonary vein isolation (PVI) and renal sympathetic denervation (RSD) may reduce the recurrence of AF in patients with CKD and hypertension. We considered that RSD could reduce the recurrence of AF in patients with CKD by modulating sympathetic hyperactivity. Our goal was to compare the impact of PVI + RSD with that of PVI alone in patients with concurrent AF and CKD. This was a single-center, prospective, longitudinal, randomized, double-blind study. Forty-five patients with controlled hypertension, symptomatic paroxysmal AF and/or persistent AF, stage 2 or 3 CKD, and a dual-chamber pacemaker were enrolled from January 2014 to January 2015. We assessed the 30-second recurrence of AF recorded by the pacemaker, 24-hour ambulatory blood pressure measurements, estimated glomerular filtration rate, albuminuria, echocardiographic parameters, and safety of RSD. No patient developed procedural or other complications. The ambulatory blood pressure measurements did not differ within the PVI + RSD group or between the PVI + RSD and PVI groups throughout the study. Significantly more patients in the PVI + RSD group than in the PVI group were free of AF at the 12-month follow-up evaluation. The PVI group had an unacceptable response to ablation with respect to changes in echocardiographic parameters, whereas these parameters improved in the PVI + RSD group. PVI + RSD were associated with a lower AF recurrence rate than PVI alone; it also improved renal function and some echocardiographic parameters. These encouraging data will serve as baseline information for further long-term studies on larger patient populations.

Renal sympathetic denervation modulates ventricular electrophysiology and has a protective effect on ischaemia-induced ventricular arrhythmia.

PubMed

Huang, Bing; Yu, Lilei; He, Bo; Lu, Zhibing; Wang, Songyun; He, Wenbo; Yang, Kang; Liao, Kai; Zhang, Ling; Jiang, Hong

2014-11-01

Recently, a beneficial effect of renal sympathetic denervation (RSD) has been seen in patients with ventricular electrical storm. However, the effect of RSD on ventricular electrophysiology remains unclear. Thirty-three mongrel dogs were included in the present study. Renal sympathetic denervation was performed by radiofrequency ablation of the adventitial surface of the renal artery. In group 1 (n = 8), programmed stimulation was performed before and after RSD to determine the ventricular effective refractory period (ERP) and action potential duration (APD) restitution properties. The same parameters were measured in five other animals that underwent sham RSD to serve as controls. In group 2 (n = 10), acute myocardial ischaemia (AMI) was induced by ligating the proximal left anterior descending coronary artery after the performance of RSD, and the incidence of ventricular arrhythmia (VA) was calculated during 1 h of recording. In another 10 dogs (group 3), AMI was induced and VA was measured with sham RSD. In group 1, RSD significantly prolonged ventricular ERP and APD, reduced the maximal slope (Smax) of the restitution curve and suppressed APD alternans at each site. Renal sympathetic denervation also significantly decreased the spatial dispersion of ERP, APD and Smax. In the five control animals, no significant electrophysiological change was detected after sham RSD. The occurrence of spontaneous VA during 1 h of AMI in group 2 was significantly lower than that in group 3. These data suggest that RSD stabilizes ventricular electrophysiological properties in normal hearts and reduces the occurrence of VA in hearts experiencing AMI. © 2014 The Authors. Experimental Physiology © 2014 The Physiological Society.

Re-establishment of anxiety in stress-sensitized mice is caused by monocyte trafficking from the spleen to the brain.

PubMed

Wohleb, Eric S; McKim, Daniel B; Shea, Daniel T; Powell, Nicole D; Tarr, Andrew J; Sheridan, John F; Godbout, Jonathan P

2014-06-15

Persistent anxiety-like symptoms may have an inflammatory-related pathophysiology. Our previous work using repeated social defeat (RSD) in mice showed that recruitment of peripheral myeloid cells to the brain is required for the development of anxiety. Here, we aimed to determine if 1) RSD promotes prolonged anxiety through redistribution of myeloid cells and 2) prior exposure to RSD sensitizes the neuroimmune axis to secondary subthreshold stress. Mice were subjected to RSD and several immune and behavioral parameters were determined .5, 8, or 24 days later. In follow-up studies, control and RSD mice were subjected to subthreshold stress at 24 days. Repeated social defeat-induced macrophage recruitment to the brain corresponded with development and maintenance of anxiety-like behavior 8 days after RSD, but neither remained at 24 days. Nonetheless, social avoidance and an elevated neuroinflammatory profile were maintained at 24 days. Subthreshold social defeat in RSD-sensitized mice increased peripheral macrophage trafficking to the brain that promoted re-establishment of anxiety. Moreover, subthreshold social defeat increased social avoidance in RSD-sensitized mice compared with naïve mice. Stress-induced monocyte trafficking was linked to redistribution of myeloid progenitor cells in the spleen. Splenectomy before subthreshold stress attenuated macrophage recruitment to the brain and prevented anxiety-like behavior in RSD-sensitized mice. These data indicate that monocyte trafficking from the spleen to the brain contributes re-establishment of anxiety in stress-sensitized mice. These findings show that neuroinflammatory mechanisms promote mood disturbances following stress-sensitization and outline novel neuroimmune interactions that underlie recurring anxiety disorders such as posttraumatic stress disorder. Copyright © 2014 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Real time quantitative colourimetric test for methamphetamine detection using digital and mobile phone technology.

PubMed

Choodum, Aree; Parabun, Kaewalee; Klawach, Nantikan; Daeid, Niamh Nic; Kanatharana, Proespichaya; Wongniramaikul, Worawit

2014-02-01

The Simon presumptive color test was used in combination with the built-in digital camera on a mobile phone to detect methamphetamine. The real-time Red-Green-Blue (RGB) basic color data was obtained using an application installed on the mobile phone and the relationship profile between RGB intensity, including other calculated values, and the colourimetric product was investigated. A wide linear range (0.1-2.5mg mL(-1)) and a low detection limit (0.0110±0.0001-0.044±0.002mg mL(-1)) were achieved. The method also required a small sample size (20μL). The results obtained from the analysis of illicit methamphetamine tablets were comparable to values obtained from gas chromatograph-flame ionization detector (GC-FID) analysis. Method validation indicated good intra- and inter-day precision (2.27-4.49%RSD and 2.65-5.62%RSD, respectively). The results suggest that this is a powerful real-time mobile method with the potential to be applied in field tests. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Ultrasound-assisted extraction of amino acids from grapes.

PubMed

Carrera, Ceferino; Ruiz-Rodríguez, Ana; Palma, Miguel; Barroso, Carmelo G

2015-01-01

Recent cultivar techniques on vineyards can have a marked influence on the final nitrogen content of grapes, specifically individual amino acid contents. Furthermore, individual amino acid contents in grapes are related to the final aromatic composition of wines. A new ultrasound-assisted method for the extraction of amino acids from grapes has been developed. Several extraction variables, including solvent (water/ethanol mixtures), solvent pH (2-7), temperature (10-70°C), ultrasonic power (20-70%) and ultrasonic frequency (0.2-1.0s(-)(1)), were optimized to guarantee full recovery of the amino acids from grapes. An experimental design was employed to optimize the extraction parameters. The surface response methodology was used to evaluate the effects of the extraction variables. The analytical properties of the new method were established, including limit of detection (average value 1.4mmolkg(-)(1)), limit of quantification (average value 2.6mmolkg(-)(1)), repeatability (average RSD=12.9%) and reproducibility (average RSD=15.7%). Finally, the new method was applied to three cultivars of white grape throughout the ripening period. Copyright © 2014 Elsevier B.V. All rights reserved.

Mass spectrometry of Escherichia coli RNA polymerase: interactions of the core enzyme with sigma70 and Rsd protein.

PubMed

Ilag, Leopold L; Westblade, Lars F; Deshayes, Caroline; Kolb, Annie; Busby, Stephen J W; Robinson, Carol V

2004-02-01

The E. coli RNA polymerase core enzyme is a multisubunit complex of 388,981 Da. To initiate transcription at promoters, the core enzyme associates with a sigma subunit to form holo RNA polymerase. Here we have used nanoflow electrospray mass spectrometry, coupled with tandem mass spectrometry, to probe the interaction of the RNA polymerase core enzyme with the most abundant sigma factor, sigma70. The results show remarkably well-resolved spectra for both the core and holo RNA polymerases. The regulator of sigma70, Rsd protein, has previously been identified as a protein that binds to free sigma70. We show that Rsd also interacts with core enzyme. In addition, by adding increasing amounts of Rsd, we show that sigma70 is displaced from holo RNA polymerase, resulting in complexes of Rsd with core and sigma70. The results argue for a model in which Rsd not only sequesters sigma70, but is also an effector of core RNA polymerase.

HPr antagonizes the anti-σ70 activity of Rsd in Escherichia coli.

PubMed

Park, Young-Ha; Lee, Chang-Ro; Choe, Mangyu; Seok, Yeong-Jae

2013-12-24

The bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) is a multicomponent system that participates in a variety of physiological processes in addition to the phosphorylation-coupled transport of numerous sugars. In Escherichia coli and other enteric bacteria, enzyme IIA(Glc) (EIIA(Glc)) is known as the central processing unit of carbon metabolism and plays multiple roles, including regulation of adenylyl cyclase, the fermentation/respiration switch protein FrsA, glycerol kinase, and several non-PTS transporters, whereas the only known regulatory role of the E. coli histidine-containing phosphocarrier protein HPr is in the activation of glycogen phosphorylase. Because HPr is known to be more abundant than EIIA(Glc) in enteric bacteria, we assumed that there might be more regulatory mechanisms connected with HPr. The ligand fishing experiment in this study identified Rsd, an anti-sigma factor known to complex with σ(70) in stationary-phase cells, as an HPr-binding protein in E. coli. Only the dephosphorylated form of HPr formed a tight complex with Rsd and thereby inhibited complex formation between Rsd and σ(70). Dephosphorylated HPr, but not phosphorylated HPr, antagonized the inhibitory effect of Rsd on σ(70)-dependent transcriptions both in vivo and in vitro, and also influenced the competition between σ(70) and σ(S) for core RNA polymerase in the presence of Rsd. Based on these data, we propose that the anti-σ(70) activity of Rsd is regulated by the phosphorylation state-dependent interaction of HPr with Rsd.

Imipramine attenuates neuroinflammatory signaling and reverses stress-induced social avoidance.

PubMed

Ramirez, Karol; Shea, Daniel T; McKim, Daniel B; Reader, Brenda F; Sheridan, John F

2015-05-01

Psychosocial stress is associated with altered immunity, anxiety and depression. Previously we showed that repeated social defeat (RSD) promoted microglia activation and social avoidance behavior that persisted for 24days after cessation of RSD. The aim of the present study was to determine if imipramine (a tricyclic antidepressant) would reverse RSD-inducedsocial avoidance and ameliorate neuroinflammatory responses. To test this, C57BL/6 mice were divided into treatment groups. One group from RSD and controls received daily injections of imipramine for 24days, following 6 cycles of RSD. Two other groups were treated with saline. RSD mice spent significantly less time in the interaction zone when an aggressor was present in the cage. Administration of imipramine reversed social avoidance behavior, significantly increasing the interaction time, so that it was similar to that of control mice. Moreover, 24days of imipramine treatment in RSD mice significantly decreased stress-induced mRNA levels for IL-6 in brain microglia. Following ex vivo LPS stimulation, microglia from mice exposed to RSD, had higher mRNA expression of IL-6, TNF-α, and IL-1β, and this was reversed by imipramine treatment. In a second experiment, imipramine was added to drinking water confirming the reversal of social avoidant behavior and decrease in mRNA expression of IL-6 in microglia. These data suggest that the antidepressant imipramine may exert its effect, in part, by down-regulating microglial activation. Copyright © 2015 Elsevier Inc. All rights reserved.

Complex regional pain syndrome type I (RSD): pathology of skeletal muscle and peripheral nerve.

PubMed

van der Laan, L; ter Laak, H J; Gabreëls-Festen, A; Gabreëls, F; Goris, R J

1998-07-01

Reflex sympathetic dystrophy (RSD) (recently reclassified as complex regional pain syndrome type I) is a syndrome occurring in extremities and, when chronic, results in severe disability and untractable pain. RSD may be accompanied by neurologic symptoms even when there is no previous neurologic lesion. There is no consensus as to the pathogenic mechanism involved in RSD. To gain insight into the pathophysiology of RSD, we studied histopathology of skeletal muscle and peripheral nerve from patients with chronic RSD in a lower extremity. In eight patients with chronic RSD, an above-the-knee amputation was performed because of a nonfunctional limb. Specimens of sural nerves, tibial nerves, common peroneal nerves, gastrocnemius muscles, and soleus muscles were obtained from the amputated legs and analyzed by light and electron microscopy. In all patients, the affected leg showed similar neurologic symptoms such as spontaneous pain, hyperpathy, allodynia, paresis, and anesthesia dolorosa. The nerves showed no consistent abnormalities of myelinated fibers. In four patients, the C-fibers showed electron microscopic pathology. In all patients, the gastrocnemius and soleus muscle specimens showed a decrease of type I fibers, an increase of lipofuscin pigment, atrophic fibers, and severely thickened basal membrane layers of the capillaries. In chronic RSD, efferent nerve fibers were histologically unaffected; from afferent fibers, only C-fibers showed histopathologic abnormalities. Skeletal muscle showed a variety of histopathologic findings, which are similar to the histologic abnormalities found in muscles of patients with diabetes.

HPr antagonizes the anti-σ70 activity of Rsd in Escherichia coli

PubMed Central

Park, Young-Ha; Lee, Chang-Ro; Choe, Mangyu; Seok, Yeong-Jae

2013-01-01

The bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) is a multicomponent system that participates in a variety of physiological processes in addition to the phosphorylation-coupled transport of numerous sugars. In Escherichia coli and other enteric bacteria, enzyme IIAGlc (EIIAGlc) is known as the central processing unit of carbon metabolism and plays multiple roles, including regulation of adenylyl cyclase, the fermentation/respiration switch protein FrsA, glycerol kinase, and several non-PTS transporters, whereas the only known regulatory role of the E. coli histidine-containing phosphocarrier protein HPr is in the activation of glycogen phosphorylase. Because HPr is known to be more abundant than EIIAGlc in enteric bacteria, we assumed that there might be more regulatory mechanisms connected with HPr. The ligand fishing experiment in this study identified Rsd, an anti-sigma factor known to complex with σ70 in stationary-phase cells, as an HPr-binding protein in E. coli. Only the dephosphorylated form of HPr formed a tight complex with Rsd and thereby inhibited complex formation between Rsd and σ70. Dephosphorylated HPr, but not phosphorylated HPr, antagonized the inhibitory effect of Rsd on σ70-dependent transcriptions both in vivo and in vitro, and also influenced the competition between σ70 and σS for core RNA polymerase in the presence of Rsd. Based on these data, we propose that the anti-σ70 activity of Rsd is regulated by the phosphorylation state-dependent interaction of HPr with Rsd. PMID:24324139

Imipramine attenuates neuroinflammatory signaling and reverses stress-induced social avoidance

PubMed Central

Ramirez, Karol; Shea, Daniel T.; McKim, Daniel B.; B.F., Reader; Sheridan, John F.

2015-01-01

Psychosocial stress is associated with altered immunity, anxiety and depression. Previously we showed that repeated social defeat (RSD) promoted microglia activation and social avoidance behavior that persisted for 24 days after cessation of RSD. The aim of the present study was to determine if imipramine (a tricyclic antidepressant) would reverse RSD-induced social avoidance and ameliorate neuroinflammatory responses. To test this, C57BL/6 mice were divided into treatment groups. One group from RSD and controls received daily injections of imipramine for 24 days, following 6 cycles of RSD. Two other groups were treated with saline. RSD mice spent significantly less time in the interaction zone when an aggressor was present in the cage. Administration of imipramine reversed social avoidance behavior, significantly increasing the interaction time, so that it was similar to that of control mice. Moreover, 24 days of imipramine treatment in RSD mice significantly decreased stress-induced mRNA levels for IL-6 in brain microglia. Following ex vivo LPS stimulation, microglia from mice exposed to RSD, had higher mRNA expression of IL-6, TNF-α, and IL-1β, and this was reversed by imipramine treatment. In a second experiment, imipramine was added to drinking water confirming the reversal of social avoidant behavior and decrease in mRNA expression of IL-6 in microglia. These data suggest that the antidepressant imipramine may exert its effect, in part, by down-regulating microglial activation. PMID:25701613

Development of Conductivity Method as an Alternative to Titration for Hydrolytic Resistance Testing Used for Evaluation of Glass Vials Used in Pharmaceutical Industry.

PubMed

Fujimori, Kiyoshi; Lee, Hans; Phillips, Joseph; Nashed-Samuel, Yasser

The European Pharmacopeia surface test to analyze the hydrolytic resistance is a common industrial method to understand and ensure the quality of produced glass vials. Hydrolytic resistance is evaluated by calculating the alkalinity of water extract from autoclaved vials by titration. As an alternative to this titration technique, a conductivity technique was assessed, which directly measures the ions in the water extract. A conductivity meter with a 12 mm diameter electrode was calibrated with a 100 μS/cm conductivity standard and carryover minimized by rinsing the probe in a water beaker per analysis. The limit of quantification at 1 μS/cm was determined as having a signal-to-noise ratio of 3 compared with the water blank. The conductivity method was selective for glass-composing elements (boron, sodium, aluminum, silicon, potassium, and calcium) within the vial extract. Accuracies of spiked conductivity standard within the range of 1 to 100 μS/cm were ±7% and had linearity with coefficient of determination (R 2 ) of ≥0.9999. Intraday precision had a relative standard deviation (RSD) (n = 5) of ≤6% for spiked conductivity standard within the range of 1 to 100 μS/cm. Interday precision had a RSD (n = 4) of ≤6% for 10 vials from three glass vial lots. Conductivity of water extracts from nine sets of seven lots of glass vials had a precise linear relationship [R 2 = 0.9876, RSD = 1% (n = 9)] with titration volumes of the same lots. Conductivity results in μS/cm could be converted to titration volumes in milliliters by a conversion factor of 0.0275. The simplicity, sample stability, and individual vial analysis of the conductivity technique were more advantageous than the current titration technique. The quality of glass vials used as primary containers in the pharmaceutical industry is of concern due to recent observations of glass flake-like delamination, or lamellae, under specific storage conditions. The current European Pharmacopoeia method to assess glass vial quality utilizes acid titration of vial extract pools to determine hydrolytic resistance or alkalinity. As an alternative to the European Pharmacopoeia method, the vial extracts were analyzed for conductivity, which directly determines the level of ions that were readily extracted from the vial surfaces. Lower quality glass would have greater surface defects that lead to higher ions extracted and higher conductivity value. The conductivity method was found to be suitable to measure the ions in water extracts and showed strong correlation with alkalinity. The advantage of the conductivity method over the alkalinity method was greater ease, lower volume requirements, stability, and flexibility in analysis. © PDA, Inc. 2017.

Modelling the large-scale redshift-space 3-point correlation function of galaxies

NASA Astrophysics Data System (ADS)

Slepian, Zachary; Eisenstein, Daniel J.

2017-08-01

We present a configuration-space model of the large-scale galaxy 3-point correlation function (3PCF) based on leading-order perturbation theory and including redshift-space distortions (RSD). This model should be useful in extracting distance-scale information from the 3PCF via the baryon acoustic oscillation method. We include the first redshift-space treatment of biasing by the baryon-dark matter relative velocity. Overall, on large scales the effect of RSD is primarily a renormalization of the 3PCF that is roughly independent of both physical scale and triangle opening angle; for our adopted Ωm and bias values, the rescaling is a factor of ˜1.8. We also present an efficient scheme for computing 3PCF predictions from our model, important for allowing fast exploration of the space of cosmological parameters in future analyses.

A Comparison Study of Summer Season Raindrop Size Distribution Between Palau and Taiwan, Two Islands in Western Pacific

NASA Astrophysics Data System (ADS)

Seela, Balaji Kumar; Janapati, Jayalakshmi; Lin, Pay-Liam; Reddy, K. Krishna; Shirooka, Ryuichi; Wang, Pao K.

2017-11-01

Raindrop size distribution (RSD) characteristics in summer season rainfall of two observational sites (Taiwan (24°58'N, 121°10'E) and Palau (7°20'N, 134°28'E)) in western Pacific are studied by using five years of impact type disdrometer data. In addition to disdrometer data, Tropical Rainfall Measuring Mission, Moderate Resolution Imaging Spectroradiometer, and ERA-Interim data sets are used to illustrate the dynamical and microphysical characteristics associated with summer season rainfall of Taiwan and Palau. Taiwan and Palau's raindrop spectra showed a significant difference, with a higher concentration of middle and large drops in Taiwan than Palau rainfall. RSD stratified on the basis of rain rate showed a higher mass-weighted mean diameter (Dm) and a lower normalized intercept parameter (log10Nw) in Taiwan than Palau rainfall. Precipitation classification into stratiform and convective regimes showed higher Dm values in Taiwan than Palau. Furthermore, for both the locations, the convective precipitation has a higher Dm value than stratiform precipitation. The radar reflectivity-rain rate relations (Z = A*Rb) of Taiwan and Palau showed a clear variation in the coefficient and a less variation in exponent values. Terrain-influenced clouds extended to higher altitudes over Taiwan resulted with higher Dm and lower log10Nw values as compared to Palau.

Spectrophotometric determination of ofloxacin in pharmaceuticals by redox reaction

NASA Astrophysics Data System (ADS)

Ramesh, P. J.; Basavaiah, K.; Rajendraprasad, N.; Devi, O. Zenita; Vinay, K. B.

2011-07-01

Two simple spectrophotometric methods have been developed to analyze ofloxacin (OFX) in pharmaceuticals. The methods are based on the oxidation of OFX by a measured excess of cerium(IV) sulfate in H2SO4 medium. This was followed by the determination of the unreacted oxidant by reacting it with either p-toluidine ( p-TD) and measuring the absorbance at 525 nm (method A) or o-dianisidine ( o-DA) and measuring the absorbance at 470 nm (method B). In both methods, the amount of cerium(IV) sulfate reacted corresponds to the amount of OFX. Calibration graphs were linear over the ranges of 0-120 and 0-4 g/ml OFX for methods A and B, respectively. The calculated molar absorptivity (2.34ṡ103 and 5.99ṡ104), Sandell sensitivity, and limit of quantification for the methods are reported. The intra-day precision (%RSD) and accuracy (%RE) were < 8.0 and ≤ 4.0%, respectively, and the inter-day RSD and RE values were within 5 and 4.0%, respectively. The applicability of the methods was demonstrated by determining OFX in tablets with an accuracy (%RE) of < 3% and precision (%RSD) of ≤2.65%. The accuracy of the methods was further ascertained by recovery experiments via a standard-addition procedure.

Endomembrane-associated RSD-3 is important for RNAi induced by extracellular silencing RNA in both somatic and germ cells of Caenorhabditis elegans

PubMed Central

Imae, Rieko; Dejima, Katsufumi; Kage-Nakadai, Eriko; Arai, Hiroyuki; Mitani, Shohei

2016-01-01

RNA silencing signals in C. elegans spread among cells, leading to RNAi throughout the body. During systemic spread of RNAi, membrane trafficking is thought to play important roles. Here, we show that RNAi Spreading Defective-3 (rsd-3), which encodes a homolog of epsinR, a conserved ENTH (epsin N-terminal homology) domain protein, generally participates in cellular uptake of silencing RNA. RSD-3 is previously thought to be involved in systemic RNAi only in germ cells, but we isolated several deletion alleles of rsd-3, and found that these mutants are defective in the spread of silencing RNA not only into germ cells but also into somatic cells. RSD-3 is ubiquitously expressed, and intracellularly localized to the trans-Golgi network (TGN) and endosomes. Tissue-specific rescue experiments indicate that RSD-3 is required for importing silencing RNA into cells rather than exporting from cells. Structure/function analysis showed that the ENTH domain alone is sufficient, and membrane association of the ENTH domain is required, for RSD-3 function in systemic RNAi. Our results suggest that endomembrane trafficking through the TGN and endosomes generally plays an important role in cellular uptake of silencing RNA. PMID:27306325

Endomembrane-associated RSD-3 is important for RNAi induced by extracellular silencing RNA in both somatic and germ cells of Caenorhabditis elegans.

PubMed

Imae, Rieko; Dejima, Katsufumi; Kage-Nakadai, Eriko; Arai, Hiroyuki; Mitani, Shohei

2016-06-16

RNA silencing signals in C. elegans spread among cells, leading to RNAi throughout the body. During systemic spread of RNAi, membrane trafficking is thought to play important roles. Here, we show that RNAi Spreading Defective-3 (rsd-3), which encodes a homolog of epsinR, a conserved ENTH (epsin N-terminal homology) domain protein, generally participates in cellular uptake of silencing RNA. RSD-3 is previously thought to be involved in systemic RNAi only in germ cells, but we isolated several deletion alleles of rsd-3, and found that these mutants are defective in the spread of silencing RNA not only into germ cells but also into somatic cells. RSD-3 is ubiquitously expressed, and intracellularly localized to the trans-Golgi network (TGN) and endosomes. Tissue-specific rescue experiments indicate that RSD-3 is required for importing silencing RNA into cells rather than exporting from cells. Structure/function analysis showed that the ENTH domain alone is sufficient, and membrane association of the ENTH domain is required, for RSD-3 function in systemic RNAi. Our results suggest that endomembrane trafficking through the TGN and endosomes generally plays an important role in cellular uptake of silencing RNA.

Design of a compressed air modulator to be used in comprehensive multidimensional gas chromatography and its application in the determination of pesticide residues in grapes.

PubMed

Pizzutti, Ionara R; Vreuls, René J J; de Kok, André; Roehrs, Rafael; Martel, Samile; Friggi, Caroline A; Zanella, Renato

2009-04-10

In this study, a new modulator that is simple, robust and presents low operation costs, was developed. This modulator uses compressed air to cool two small portions in the first centimeters of the second chromatographic column of a comprehensive multidimensional gas chromatography (GCxGC) system. The results show a variation in the peak area less than 3 and 5% to alkanes and pesticides, respectively. The standard deviations for the retention times in the first and second dimension are around 0.05 min and 0.05s for all the compounds. The system was optimized with n-alkanes. The GCxGC system proposed was applied in the determination of pyrethroid pesticides (bifenthrin, cypermethrin, deltamethrin, fenvalerate, esfenvalerate, cis- and trans-permethrin) in grape samples. Samples were extracted by the mini-Luke modified method and pesticides were quantified by comprehensive multidimensional gas chromatography with micro electron-capture detection (microECD). The values of method limit of quantification (LOQ) were 0.01-0.02 mg kg(-1) for all studied pyrethroid and the values of recovery were between 94.3 and 115.2%, with good precision (RSD<18.4%), demonstrating that the performance of the total method consisting of a modified Luke extraction method and determination by GCxGC-microECD are satisfactory. This study also showed that the system using a modulator with a double jet of compressed air has the potential for application in the analysis of a wider range of pesticide residues in other commodities since it provides low values of LOQ with acceptable accuracy and precision.

Application of derivative ratio spectrophotometry for determination of β-carotene and astaxanthin from Phaffia rhodozyma extract*

PubMed Central

Ni, Hui; He, Guo-qing; Ruan, Hui; Chen, Qi-he; Chen, Feng

2005-01-01

A derivative ratio spectrophotometric method was used for the simultaneous determination of β-carotene and astaxanthin produced from Phaffia rhodozyma. Absorbencies of a series of the standard carotenoids in the range of 441 nm to 490 nm demonstrated that their absorptive spectra accorded with Beer’s law and that the additivity when the concentrations of β-carotene and astaxanthin and their mixture were within the range of 0 to 5 µg/ml, 0 to 6 µg/ml, and 0 to 6 µg/ml, respectively. When the wavelength interval (Δλ) at 2 nm was selected to calculate the first derivative ratio spectra values, the first derivative amplitudes at 461 nm and 466 nm were suitable for quantitatively determining β-carotene and astaxanthin, respectively. Effect of divisor on derivative ratio spectra could be neglected; any concentration used as divisor in range of 1.0 to 4.0 µg/ml is ideal for calculating the derivative ratio spectra values of the two carotenoids. Calibration graphs were established for β-carotene within 0–6.0 µg/ml and for astaxanthin within 0–5.0 µg/ml with their corresponding regressive equations in: y=−0.0082x−0.0002 and y=0.0146x−0.0006, respectively. R-square values in excess of 0.999 indicated the good linearity of the calibration graphs. Sample recovery rates were found satisfactory (>99%) with relative standard deviations (RSD) of less than 5%. This method was successfully applied to simultaneous determination of β-carotene and astaxanthin in the laboratory-prepared mixtures and the extract from the Phaffia rhodozyma culture. PMID:15909336

Fast determination of pesticides and other contaminants of emerging concern in treated wastewater using direct injection coupled to highly sensitive ultra-high performance liquid chromatography-tandem mass spectrometry.

PubMed

Campos-Mañas, Marina Celia; Plaza-Bolaños, Patricia; Sánchez-Pérez, José Antonio; Malato, Sixto; Agüera, Ana

2017-07-21

It is well known that wastewater treatment plant (WWTP) effluents usually contain micropollutants such as pharmaceuticals (or their transformation products, TPs) or pesticides, which is a major issue when evaluating their possible reuse (e.g. for irrigation in agriculture). In search for an improved accuracy and simplicity, methods based on the direct injection of the sample (DI) represent a recent trend taking advantage of the increasing sensitivity of new mass spectrometry (MS) instruments. Thus, the present study shows the development and validation of a DI-based method by ultra-high-performance liquid chromatography quadrupole-linear ion trap analyser (UHPLC-QqLIT-MS/MS). The proposed method was applied to the monitoring of 115 organic microcontaminants (including pharmaceuticals, TPs and pesticides) at the ngL -1 /μgL -1 level in wastewater effluents from urban WWTPs. Sample pre-treatment was reduced to acetonitrile addition and filtration of the mixture previous to LC-MS analysis. Total analysis time was <15min. A subsequent validation protocol was carried out in treated WW (TWW), following indications of SANTE and Eurachem Guidelines. Linearity and matrix effect were evaluated in the range of 10-1000ngL -1 . 70% of the analytes showed a moderate matrix effect (≤25%). Trueness (expressed as recovery) and precision (calculated as relative standard deviation, RSD) were evaluated at four concentration levels (20, 50, 500 and 1000ngL -1 ) in TWW samples. The LODs ranged from 1 to 357ngL -1 and the LOQs from 10 to 500ngL -1 . 92% of the compounds showed limits of quantification ≤100ngL -1 . In most cases, mean recoveries were in the range 70-120%, and RSD values were ≤20%. The validated method was successfully applied to the analysis of 10 TWW samples, demonstrating the occurrence of 67 target compounds at concentration levels from 26705ngL -1 (4-aminoantipyrine) to 10ngL -1 (tebuconazole and bezafibrate). Copyright © 2017 Elsevier B.V. All rights reserved.

Stress-induced recruitment of bone marrow-derived monocytes to the brain promotes anxiety-like behavior.

PubMed

Wohleb, Eric S; Powell, Nicole D; Godbout, Jonathan P; Sheridan, John F

2013-08-21

Social stress is associated with altered immunity and higher incidence of anxiety-related disorders. Repeated social defeat (RSD) is a murine stressor that primes peripheral myeloid cells, activates microglia, and induces anxiety-like behavior. Here we show that RSD-induced anxiety-like behavior corresponded with an exposure-dependent increase in circulating monocytes (CD11b(+)/SSC(lo)/Ly6C(hi)) and brain macrophages (CD11b(+)/SSC(lo)/CD45(hi)). Moreover, RSD-induced anxiety-like behavior corresponded with brain region-dependent cytokine and chemokine responses involved with myeloid cell recruitment. Next, LysM-GFP(+) and GFP(+) bone marrow (BM)-chimeric mice were used to determine the neuroanatomical distribution of peripheral myeloid cells recruited to the brain during RSD. LysM-GFP(+) mice showed that RSD increased recruitment of GFP(+) macrophages to the brain and increased their presence within the perivascular space (PVS). In addition, RSD promoted recruitment of GFP(+) macrophages into the PVS and parenchyma of the prefrontal cortex, amygdala, and hippocampus of GFP(+) BM-chimeric mice. Furthermore, mice deficient in chemokine receptors associated with monocyte trafficking [chemokine receptor-2 knockout (CCR2(KO)) or fractalkine receptor knockout (CX3CR1(KO))] failed to recruit macrophages to the brain and did not develop anxiety-like behavior following RSD. Last, RSD-induced macrophage trafficking was prevented in BM-chimeric mice generated with CCR2(KO) or CX3CR1(KO) donor cells. These findings indicate that monocyte recruitment to the brain in response to social stress represents a novel cellular mechanism that contributes to the development of anxiety.

Stress-Induced Recruitment of Bone Marrow-Derived Monocytes to the Brain Promotes Anxiety-Like Behavior

PubMed Central

Wohleb, Eric S.; Powell, Nicole D.

2013-01-01

Social stress is associated with altered immunity and higher incidence of anxiety-related disorders. Repeated social defeat (RSD) is a murine stressor that primes peripheral myeloid cells, activates microglia, and induces anxiety-like behavior. Here we show that RSD-induced anxiety-like behavior corresponded with an exposure-dependent increase in circulating monocytes (CD11b+/SSClo/Ly6Chi) and brain macrophages (CD11b+/SSClo/CD45hi). Moreover, RSD-induced anxiety-like behavior corresponded with brain region-dependent cytokine and chemokine responses involved with myeloid cell recruitment. Next, LysM-GFP+ and GFP+ bone marrow (BM)-chimeric mice were used to determine the neuroanatomical distribution of peripheral myeloid cells recruited to the brain during RSD. LysM-GFP+ mice showed that RSD increased recruitment of GFP+ macrophages to the brain and increased their presence within the perivascular space (PVS). In addition, RSD promoted recruitment of GFP+ macrophages into the PVS and parenchyma of the prefrontal cortex, amygdala, and hippocampus of GFP+ BM-chimeric mice. Furthermore, mice deficient in chemokine receptors associated with monocyte trafficking [chemokine receptor-2 knockout (CCR2KO) or fractalkine receptor knockout (CX3CR1KO)] failed to recruit macrophages to the brain and did not develop anxiety-like behavior following RSD. Last, RSD-induced macrophage trafficking was prevented in BM-chimeric mice generated with CCR2KO or CX3CR1KO donor cells. These findings indicate that monocyte recruitment to the brain in response to social stress represents a novel cellular mechanism that contributes to the development of anxiety. PMID:23966702

Post-Planck constraints on interacting vacuum energy

NASA Astrophysics Data System (ADS)

Wang, Yuting; Wands, David; Zhao, Gong-Bo; Xu, Lixin

2014-07-01

We present improved constraints on an interacting vacuum model using updated astronomical observations including the first data release from Planck. We consider a model with one dimensionless parameter, α, describing the interaction between dark matter and vacuum energy (with fixed equation of state w=-1). The background dynamics correspond to a generalized Chaplygin gas cosmology, but the perturbations have a zero sound speed. The tension between the value of the Hubble constant, H0, determined by Planck data plus WMAP polarization (Planck +WP) and that determined by the Hubble Space Telescope (HST) can be alleviated by energy transfer from dark matter to vacuum (α>0). A positive α increases the allowed values of H0 due to parameter degeneracy within the model using only cosmic microwave background data. Combining with additional data sets of including supernova type Ia (SN Ia) and baryon acoustic oscillation (BAO), we can significantly tighten the bounds on α. Redshift-space distortions (RSD), which constrain the linear growth of structure, provide the tightest constraints on vacuum interaction when combined with Planck+WP, and prefer energy transfer from vacuum to dark matter (α<0) which suppresses the growth of structure. Using the combined data sets of Planck +WP+Union2.1+BAO+RSD, we obtain the constraint on α to be -0.083<α<-0.006 (95% C.L.), allowing low H0 consistent with the measurement from 6dF Galaxy survey. This interacting vacuum model can alleviate the tension between RSD and Planck +WP in the ΛCDM model for α <0, or between HST measurements of H0 and Planck+WP for α>0, but not both at the same time.

A comparative study of three detection techniques for Leifsonia xyli subsp. xyli, the causal pathogen of sugarcane ratoon stunting disease

USDA-ARS?s Scientific Manuscript database

Ratoon stunting disease (RSD), which is caused by the bacterium Leifsonia xyli subsp. xyli (Lxx), is now recognized worldwide as the most economically devastating disease impacting sugarcane. RSD causes significant yield losses and variety degradation. Diagnosis of RSD is challenging because it does...

Isolation and characterization of resistant gene analogs from RSD resistant and susceptible sugarcane clones: A progress report

USDA-ARS?s Scientific Manuscript database

Ratoon stunting disease (RSD) can decrease sugarcane yield by 5 to 15% if not properly managed. Currently, the disease is primarily managed by two approaches: breeding for RSD resistance and through sanitation, i.e., cleaning equipment and a clean seed program. Understanding the molecular basis of...

40 CFR 266.106 - Standards to control metals emissions.

Code of Federal Regulations, 2013 CFR

2013-07-01

...-specific doses (RSDs) are listed for the carcinogenic metals. The RSD for a metal is the acceptable ambient... RSD as described in paragraph (d)(3) of this section. (3) Carcinogenic metals. For the carcinogenic... person resides on site) to the risk-specific dose (RSD) for all carcinogenic metals emitted shall not...

40 CFR 266.106 - Standards to control metals emissions.

Code of Federal Regulations, 2012 CFR

2012-07-01

...-specific doses (RSDs) are listed for the carcinogenic metals. The RSD for a metal is the acceptable ambient... RSD as described in paragraph (d)(3) of this section. (3) Carcinogenic metals. For the carcinogenic... person resides on site) to the risk-specific dose (RSD) for all carcinogenic metals emitted shall not...

40 CFR 266.106 - Standards to control metals emissions.

Code of Federal Regulations, 2014 CFR

2014-07-01

...-specific doses (RSDs) are listed for the carcinogenic metals. The RSD for a metal is the acceptable ambient... RSD as described in paragraph (d)(3) of this section. (3) Carcinogenic metals. For the carcinogenic... person resides on site) to the risk-specific dose (RSD) for all carcinogenic metals emitted shall not...

Regulation of Global Transcription in Escherichia coli by Rsd and 6S RNA

PubMed Central

Lal, Avantika; Krishna, Sandeep; Seshasayee, Aswin Sai Narain

2018-01-01

In Escherichia coli, the sigma factor σ70 directs RNA polymerase to transcribe growth-related genes, while σ38 directs transcription of stress response genes during stationary phase. Two molecules hypothesized to regulate RNA polymerase are the protein Rsd, which binds to σ70, and the non-coding 6S RNA which binds to the RNA polymerase-σ70 holoenzyme. Despite multiple studies, the functions of Rsd and 6S RNA remain controversial. Here we use RNA-Seq in five phases of growth to elucidate their function on a genome-wide scale. We show that Rsd and 6S RNA facilitate σ38 activity throughout bacterial growth, while 6S RNA also regulates widely different genes depending upon growth phase. We discover novel interactions between 6S RNA and Rsd and show widespread expression changes in a strain lacking both regulators. Finally, we present a mathematical model of transcription which highlights the crosstalk between Rsd and 6S RNA as a crucial factor in controlling sigma factor competition and global gene expression. PMID:29686109

Regulation of Global Transcription in Escherichia coli by Rsd and 6S RNA.

PubMed

Lal, Avantika; Krishna, Sandeep; Seshasayee, Aswin Sai Narain

2018-05-31

In Escherichia coli , the sigma factor σ 70 directs RNA polymerase to transcribe growth-related genes, while σ 38 directs transcription of stress response genes during stationary phase. Two molecules hypothesized to regulate RNA polymerase are the protein Rsd, which binds to σ 70 , and the non-coding 6S RNA which binds to the RNA polymerase-σ 70 holoenzyme. Despite multiple studies, the functions of Rsd and 6S RNA remain controversial. Here we use RNA-Seq in five phases of growth to elucidate their function on a genome-wide scale. We show that Rsd and 6S RNA facilitate σ 38 activity throughout bacterial growth, while 6S RNA also regulates widely different genes depending upon growth phase. We discover novel interactions between 6S RNA and Rsd and show widespread expression changes in a strain lacking both regulators. Finally, we present a mathematical model of transcription which highlights the crosstalk between Rsd and 6S RNA as a crucial factor in controlling sigma factor competition and global gene expression. Copyright © 2018 Lal et al.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tandon, Lav; Colletti, Lisa M.; Drake, Lawrence R.

This report discusses the process used to prove in the SRNL-Rev.2 coulometer for isotopic data analysis used in the special plutonium material project. In May of 2012, the PAR 173 coulometer system that had been the workhorse of the Plutonium Assay team since the early 1970s became inoperable. A new coulometer system had been purchased from Savannah River National Laboratory (SRNL) and installed in August of 2011. Due to funding issues the new system was not qualified at that time. Following the failure of the PAR 173, it became necessary to qualify the new system for use in Process 3401a,more » Plutonium Assay by Controlled Coulometry. A qualification plan similar to what is described in PQR -141a was followed. Experiments were performed to establish a statistical summary of the performance of the new system by monitoring the repetitive analysis of quality control sample, PEOL, and the assay of plutonium metals obtained from the Plutonium Exchange Program. The data for the experiments was acquired using work instructions ANC125 and ANC195. Figure 1 shows approximately 2 years of data for the PEOL material obtained using the PAR 173. The required acceptance criteria for the sample are that it returns the correct value for the quality control material of 88.00% within 2 sigma (95% Confidence Interval). It also must meet daily precision standards that are set from the historical data analysis of decades of data. The 2 sigma value that is currently used is 0.146 % as evaluated by the Statistical Science Group, CCS-6. The average value of the PEOL quality control material run in 10 separate days on the SRNL-03 coulometer is 87.98% with a relative standard deviation of 0.04 at the 95% Confidence interval. The date of data acquisition is between 5/23/2012 to 8/1/2012. The control samples are run every day experiments using the coulometer are carried out. It is also used to prove an instrument is in statistical control before any experiments are undertaken. The total number of replicate controls run with the new coulometer to date, is n=18. This value is identical to that calculated by the LANL statistical group for this material from data produced by the PAR 173 system over the period of October 2007 to May 2011. The final validation/verification test was to run a blind sample over multiple days. AAC participates in a plutonium exchange program which supplies blind Pu metal samples to the group on a regular basis. The Pu material supplied for this study was ran using the PAR 173 in the past and more recently with the new system. Table 1a contains the values determined through the use of the PAR 173 and Table 1b contains the values obtained with the new system. The Pu assay value obtained on the SRNL system is for paired analysis and had a value of 98.88+/-0.07% RSD at 95% CI. The Pu assay value (decay corrected to July 2012) of the material determined in prior measurements using the PAR173 is 99.05 +/- 0.06 % RSD at 95% CI. We believe that the instrument is adequate to meet the needs of the program.« less

Simultaneous determination of flubendiamide its metabolite desiodo flubendiamide residues in cabbage, tomato and pigeon pea by HPLC.

PubMed

Paramasivam, M; Banerjee, Hemanta

2011-10-01

A sensitive and simple method for simultaneous analysis of flubendiamide and its metabolite desiodo flubendiamide in cabbage, tomato and pigeon pea has been developed. The residues were extracted with QuEChERS method followed by dispersive solid-phase extraction with primary secondary amine sorbent to remove co extractives, prior to analysis by HPLC coupled with UV-Vis detector. The recoveries of flubendiamide and desiodo flubendiamide were ranged from 85.1 to 98.5% and 85.9 to 97.1% respectively with relative standard deviations (RSD) less than 5% and sensitivity of 0.01 μg g(-1). The method offers a less expensive and safer alternative to the existing residue analysis methods for vegetables. © Springer Science+Business Media, LLC 2011

Rapid quantitative detection of glucose content in glucose injection by reaction headspace gas chromatography.

PubMed

Xie, Wei-Qi; Gong, Yi-Xian; Yu, Kong-Xian

2017-10-20

This work investigates an automated technique for rapid detecting the glucose content in glucose injection by reaction headspace gas chromatography (HS-GC). This method is based on the oxidation reaction of glucose in glucose injection with potassium dichromate. The carbon dioxide (CO 2 ) formed from the oxidation reaction can be quantitatively detected by GC. The results show that the relative standard deviation (RSD) of the present method was within 2.91%, and the measured glucose contents in glucose injection closely match those quantified by the reference method (relative differences <6.45%). The new HS-GC technique is rapid, practical and can be used to the batch detection of the glucose content in glucose injection related applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Plant tissue-based chemiluminescence biosensor for ethanol.

PubMed

Huang, Yuming; Wu, Fangqiong

2006-07-01

A plant tissue-based chemiluminescence biosensor for ethanol based on using mushroom (Agaricus bisporus) tissue as the recognition element is proposed in this paper. The principle for ethanol sensing relies on the luminol-potassium hexacyanoferrate(III)-hydrogen peroxide transducer reaction, in which hydrogen peroxide is produced from the ethanol enzymatic catalytic oxidation by oxygen under the catalysis of alcohol oxidase in the tissue column. Under optimum conditions, the method allowed the measurement of ethanol in the range of 0.001 - 2 mmol/l with a detection limit (3 sigma) of 0.2 micromol/l. The relative standard deviation (RSD) was 4.14% (n = 11) for 0.05 mmol/l ethanol. The proposed method has been applied to the determination of ethanol in biological fluids and beverages with satisfactory results.

Application of ion chromatography to the determination of water-soluble inorganic and organic ions in atmospheric aerosols.

PubMed

Yu, Xue-Chun; He, Ke-Bin; Ma, Yong-Liang; Yang, Fu-Mo; Duan, Feng-Kui; Zheng, Ai-Hua; Zhao, Cheng-Yi

2004-01-01

A simple, sensitive and convenient ion chromatography(IC) method was established for the simultaneous determination of twelve water-soluble inorganic anions(F- , Cl- , NO2(-), NO3(-), SO3(2-), SO4(2-) , PO4(3-)), and fifteen water-soluble organic ions(formate, acetate, MSA, oxalate, malonate, succinate, phthalates, etc.) in atmospheric aerosols. The linear concentrations ranged from 0.005 microg/m3 to 500 microg/m3 ( r = 0.999-0.9999). The relative standard deviation (RSD) were 0.43%-2.00% and the detection limits were from 2.7 ng/m3 to 88 ng/m3. The proposed method was successfully applied to the simultaneous determination of those inorganic ions and organic ions in PM2.5 of Beijing.

Development and application of a sol-gel immunosorbent-based method for the determination of isoproturon in surface water.

PubMed

Zhang, Xiuli; Martens, Dieter; Krämer, Petra M; Kettrup, Antonius A; Liang, Xinmiao

2006-01-13

An immunosorbent was fabricated by encapsulation of monoclonal anti-isoproturon antibodies in sol-gel matrix. The immunosorbent-based loading, rinsing and eluting processes were optimized. Based on these optimizations, the sol-gel immunosorbent (SG-IS) selectively extracted isoproturon from an artificial mixture of 68 pesticides. In addition to this high selectivity, the SG-IS proved to be reusable. The SG-IS was combined with liquid chromatography-tandem mass spectrometry (LC-MS-MS) to determine isoproturon in surface water, and the linear range was up to 2.2 microg/l with correlation coefficient higher than 0.99 and relative standard deviation (RSD) lower than 5% (n=8). The limit of quantitation (LOQ) for 25-ml surface water sample was 5 ng/l.

Shared and Unique Risk Factors Underlying Mathematical Disability and Reading and Spelling Disability.

PubMed

Slot, Esther M; van Viersen, Sietske; de Bree, Elise H; Kroesbergen, Evelyn H

2016-01-01

High comorbidity rates have been reported between mathematical learning disabilities (MD) and reading and spelling disabilities (RSD). Research has identified skills related to math, such as number sense (NS) and visuospatial working memory (visuospatial WM), as well as to literacy, such as phonological awareness (PA), rapid automatized naming (RAN) and verbal short-term memory (Verbal STM). In order to explain the high comorbidity rates between MD and RSD, 7-11-year-old children were assessed on a range of cognitive abilities related to literacy (PA, RAN, Verbal STM) and mathematical ability (visuospatial WM, NS). The group of children consisted of typically developing (TD) children (n = 32), children with MD (n = 26), children with RSD (n = 29), and combined MD and RSD (n = 43). It was hypothesized that, in line with the multiple deficit view on learning disorders, at least one unique predictor for both MD and RSD and a possible shared cognitive risk factor would be found to account for the comorbidity between the symptom dimensions literacy and math. Secondly, our hypotheses were that (a) a probabilistic multi-factorial risk factor model would provide a better fit to the data than a deterministic single risk factor model and (b) that a shared risk factor model would provide a better fit than the specific multi-factorial model. All our hypotheses were confirmed. NS and visuospatial WM were identified as unique cognitive predictors for MD, whereas PA and RAN were both associated with RSD. Also, a shared risk factor model with PA as a cognitive predictor for both RSD and MD fitted the data best, indicating that MD and RSD might co-occur due to a shared underlying deficit in phonological processing. Possible explanations are discussed in the context of sample selection and composition. This study shows that different cognitive factors play a role in mathematics and literacy, and that a phonological processing deficit might play a role in the occurrence of MD and RSD.

A new perspective on the raindrop size distribution and its implications for retrievals of light rainfall

NASA Astrophysics Data System (ADS)

Gatlin, P. N.; Thurai, M.; Petersen, W. A.; Bringi, V. N.

2017-12-01

As GPM facilitates precipitation estimation at higher latitudes where light rainfall is more common it becomes more important that we can fully describe the raindrop size distribution (RSD) across the continuum of observed raindrop sizes. An adequate understanding and the capability to represent the RSD in light rain and drizzle extends from GPM radar algorithms into radiometer-based algorithms, where auto-conversion from cloud to rainwater contents and size distributions becomes important for light rain/drizzle estimation. This study provides insights into the effect of small raindrops on our ability to accurately map rainfall. The RSD has been widely defined using a gamma distribution—the assumption often being verified and approach being reinforced using measurements that imperfectly measure the small end of the RSD. However, we find that the gamma model as it is applied in its current form, to include commonly used disdrometer measurements to define it, is not capable of accurately describing the small raindrops we have observed during light rainfall. We demonstrate the difficulty encountered at light rain rates (e.g., 0.5 mm/hr or less) and for drops typically < 0.6 - 0.7 mm in diameter using a disdrometer with a pixel resolution of 50 microns operated alongside a 2DVD, with both instruments inside a small DFIR wind fence. Measurements were made in two locations with different climates—Greely, Colorado and Huntsville, Alabama. The resultant comparison reveals that the gamma RSD model overestimates the characteristic raindrop diameter (Dm), especially for light rainfall. A generalized gamma distribution provides a closer fit to the RSD observations across the continuum of raindrop sizes and highlights a drizzle mode of the RSD exists that would otherwise not be described with the commonly used gamma RSD model. Our analysis also suggests that RSD-based separation of stratiform and convective rainfall requires special consideration for light rainfall cases, especially those with small mass-weighted mean diameters (Dm < 0.6 mm).

Ropivacaine and Bupivacaine prevent increased pain sensitivity without altering neuroimmune activation following repeated social defeat stress.

PubMed

Sawicki, Caroline M; Kim, January K; Weber, Michael D; Jarrett, Brant L; Godbout, Jonathan P; Sheridan, John F; Humeidan, Michelle

2018-03-01

Mounting evidence indicates that stress influences the experience of pain. Exposure to psychosocial stress disrupts bi-directional communication pathways between the central nervous system and peripheral immune system, and can exacerbate the frequency and severity of pain experienced by stressed subjects. Repeated social defeat (RSD) is a murine model of psychosocial stress that recapitulates the immune and behavioral responses to stress observed in humans, including activation of stress-reactive neurocircuitry and increased pro-inflammatory cytokine production. It is unclear, however, how these stress-induced neuroimmune responses contribute to increased pain sensitivity in mice exposed to RSD. Here we used a technique of regional analgesia with local anesthetics in mice to block the development of mechanical allodynia during RSD. We next investigated the degree to which pain blockade altered stress-induced neuroimmune activation and depressive-like behavior. Following development of a mouse model of regional analgesia with discrete sensory blockade over the dorsal-caudal aspect of the spine, C57BL/6 mice were divided into experimental groups and treated with Ropivacaine (0.08%), Liposomal Bupivacaine (0.08%), or Vehicle (0.9% NaCl) prior to exposure to stress. This specific region was selected for analgesia because it is the most frequent location for aggression-associated pain due to biting during RSD. Mechanical allodynia was assessed 12 h after the first, third, and sixth day of RSD after resolution of the sensory blockade. In a separate experiment, social avoidance behavior was determined after the sixth day of RSD. Blood, bone marrow, brain, and spinal cord were collected for immunological analyses after the last day of RSD in both experiments following behavioral assessments. RSD increased mechanical allodynia in an exposure-dependent manner that persisted for at least one week following cessation of the stressor. Mice treated with either Ropivacaine or Liposomal Bupivacaine did not develop mechanical allodynia following exposure to stress, but did develop social avoidance behavior. Neither drug affected stress-induced activation of monocytes in the bone marrow, blood, or brain. Neuroinflammatory responses developed in all treatment groups, as evidenced by elevated IL-1β mRNA levels in the brain and spinal cord after RSD. In this study, psychosocial stress was associated with increased pain sensitivity in mice. Development of mechanical allodynia with RSD was blocked by regional analgesia with local anesthetics, Ropivacaine or Liposomal Bupivacaine. Despite blocking mechanical allodynia, these anesthetic interventions did not prevent neuroimmune activation or social avoidance associated with RSD. These data suggest that stress-induced neuroinflammatory changes are not associated with increased sensitivity to pain following RSD. Thus, blocking peripheral nociception was effective in inhibiting enhanced pain signaling without altering stress-induced immune or behavioral responses. Copyright © 2017 Elsevier Inc. All rights reserved.

Discipline for Students with Disabilities in the Recovery School District (RSD) of New Orleans

ERIC Educational Resources Information Center

Jeffers, Elizabeth K.

2014-01-01

This article focuses on special education in New Orleans post Hurricane Katrina. After Hurricane Katrina, Louisiana's Recovery School District (RSD) took over 102 of the city's 128 schools with the stated goal of creating a "choice district" for parents. This "choice distric"' is made up of RSD direct-run schools, Orleans…

Effects of renal sympathetic denervation on cardiac sympathetic activity and function in patients with therapy resistant hypertension.

PubMed

van Brussel, Peter M; Eeftinck Schattenkerk, Daan W; Dobrowolski, Linn C; de Winter, Robbert J; Reekers, Jim A; Verberne, Hein J; Vogt, Liffert; van den Born, Bert-Jan H

2016-01-01

Renal sympathetic denervation (RSD) is currently being investigated in multiple studies of sympathetically driven cardiovascular diseases such as heart failure and arrhythmias. Our aim was to assess systemic and cardiac sympatholytic effects of RSD by the measurement of cardiac sympathetic activity and cardiovascular parameters. A total of 21 consecutive patients with refractory hypertension (daytime ambulatory blood pressure (BP)≥150/100 mmHg despite the use of 3 or more antihypertensive drugs), no evidence for secondary hypertension and normal renovascular anatomy were included. RSD was performed with the Medtronic Symplicity renal denervation catheter with an average of 4.2 (range 3-6) ablations per renal artery. To assess cardiac sympathetic activity, 123I-mIBG cardiac scintigraphy was performed before and 6 weeks after. In addition, the effect of RSD on peripheral BP and cardiac hemodynamics were assessed non-invasively. 123I-mIBG uptake before and after RSD was 1.7±0.4% vs. 1.7±0.5% at 15 min. and 1.4±0.4% vs. 1.5±0.5% after 4 h. As a consequence, washout rate was similar before (33.7±11.7%) and after RSD (30.1±12.6%, p=0.27). In line with earlier RSD studies, a significant drop in systolic office BP (-12.2 mmHg, p=0.04) was detected, whereas the decrease in ambulatory BP was not significant. No changes were seen in heart rate, stroke volume or left ventricular contractility, both in supine position and after standing. In concert with previous reports, RSD leads to a significant drop in office BP. However, a reduction in sympathetic activity could not be demonstrated on a cardiac level. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Selective molecularly imprinted polymer combined with restricted access material for in-tube SPME/UHPLC-MS/MS of parabens in breast milk samples.

PubMed

Souza, Israel D; Melo, Lidervan P; Jardim, Isabel C S F; Monteiro, Juliana C S; Nakano, Ana Marcia S; Queiroz, Maria Eugênia C

2016-08-17

A new molecularly imprinted polymer modified with restricted access material (a hydrophilic external layer), (MIP-RAM) was synthesized via polymerization in situ in an open fused silica capillary. This stationary phase was used as sorbent for in-tube solid phase microextraction (in-tube SPME) to determine parabens in breast milk samples by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Scanning electron micrographs (SEM) illustrate MIP surface modification after glycerol dimethacrylate (hydrophilic monomer) incorporation. The interaction between parabens and MIP-RAM was investigated by Fourier-transform infrared (FTIR) spectroscopy. The Scatchard plot for MIP-RAM presented two linear parts with different slopes, illustrating binding sites with high- and low-affinity. Endogenous compounds exclusion from the MIP-RAM capillary was demonstrated by in-tube SPME/LC-UV assays carried out with blank milk samples. The in-tube SPME/UHPLC-MS/MS method presented linear range from 10 ng mL(-1) (LLOQ) to 400 ng mL(-1) with coefficients of determination higher than 0.99, inter-assay precision with coefficient of variation (CV) values ranging from 2 to 15%, and inter-assay accuracy with relative standard deviation (RSD) values ranging from -1% to 19%. Analytical validation parameters attested that in-tube SPME/UHPLC-MS/MS is an appropriate method to determine parabens in human milk samples to assess human exposure to these compounds. Analysis of breast milk samples from lactating women demonstrated that the proposed method is effective. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of a short path thermal desorption-gas chromatography/mass spectrometry method for the determination of polycyclic aromatic hydrocarbons in indoor air.

PubMed

Li, Yingjie; Xian, Qiming; Li, Li

2017-05-12

Polycyclic aromatic hydrocarbons (PAHs) are present in petroleum based products and are combustion by-products of organic matters. Determination of levels of PAHs in the indoor environment is important for assessing human exposure to these chemicals. A new short path thermal desorption (SPTD) gas chromatography/mass spectrometry (GC/MS) method for determining levels of PAHs in indoor air was developed. Thermal desorption (TD) tubes packed with glass beads, Carbopack C, and Carbopack B in sequence, were used for sample collection. Indoor air was sampled using a small portable pump over 7 days at 100ml/min. Target PAHs were thermally released and introduced into the GC/MS for analysis through the SPTD unit. During tube desorption, PAHs were cold trapped (-20°C) at the front end of the GC column. Thermal desorption efficiencies were 100% for PAHs with 2 and 3 rings, and 99-97% for PAHs with 4-6 rings. Relative standard deviation (RSD) values among replicate samples spiked at three different levels were around 10-20%. The detection limit of this method was at or below 0.1μg/m 3 except for naphthalene (0.61μg/m 3 ), fluorene (0.28μg/m 3 ) and phenanthrene (0.35μg/m 3 ). This method was applied to measure PAHs in indoor air in nine residential homes. The levels of PAHs in indoor air found in these nine homes are similar to indoor air values reported by others. Copyright © 2017 Elsevier B.V. All rights reserved.

[Improvement of the method for methylmercury determination in aquatic products using liquid chromatography online coupled with atomic fluorescence spectrometry].

PubMed

Shang, Xiaohong; Zhao, Yunfeng; Zhang, Lei; Li, Xiaowei; Wu, Yongning

2011-07-01

The improvement method was developed for methylmercury determination using liquid chromatography online coupled with cold vapor atomic fluorescence spectrometry (LC-CV-AFS). Cysteine was used as complexing agent in mobile phase instead of mercaptoethanol. Under the optimized conditions, baseline separation of mercury species could be achieved within 8 min on a C18 column with a mobile phase of 5% (v/v) acetonitrile-1 g/L L-cysteine-50 mmol/L ammonium acetate aqueous solution. The linear range of calibration curve of methylmercury was 1-50 microg/L and the limit of detection (S/N = 3) for methylmercury was 0.3 microg/L. Ultrasonication assisted hydrochloric acid extraction was used to extract methylmercury from seafood samples. The sample extract was cleaned up by a C18 solid phase extraction (SPE) cartridge. For validation of the method, certified reference materials and spiked seafood samples were analyzed. The determined methylmercury contents of certified reference materials NIST1566b, BCR464 and GBW10029 agreed well with the certified values. The determined methylmercury values for Food Analysis Performance Assessment Scheme (FAPAS) sample 07115 were satisfied. The recoveries of methylmercury in seafood samples at three spiked levels (10, 50 and 500 microg/kg) ranged from 89% to 112%, including cooked seafood food. The precision of the method based on relative standard deviation (RSD) was not more than 7%. The present method of LC-CV-AFS is accurate, sensitive, simple, and can meet the demand of methylmercury determination in seafood.

Simultaneous determination of four neuroprotective compounds of Tilia amurensis by high performance liquid chromatography coupled with diode array detector

PubMed Central

Lee, Bohyung; Weon, Jin Bae; Yun, Bo-Ra; Lee, Jiwoo; Eom, Min Rye; Ma, Choong Je

2014-01-01

Background: Tilia amurensis consists of various compounds, such as flavonoids and terpenoids. Objective: A simple and reliable high performance liquid chromatography (HPLC) coupled with the diode array detector (DAD) method has been established for simultaneous determination of epicatechin, nudiposide, lyoniside, and scopoletin isolated from Tilia amurensis. Materials and Methods: Optimum separations were obtained with a SHISEIDO C18 column by gradient eluton, with 0.1% Trifluoroacetic acid (TFA) water-methanol as the mobile phase. The gradient elution system was completed within 40 minutes. The flow rate and detection wavelength were 1 mL/minute, 205 nm, 250 nm, and 280 nm, respectively. Results: Validation of the analytical method was evaluated by linearity, precision, and the accuracy test. The calibration curve was linear over the established range with R2 > 0.997. The limit of detection (LOD) and limit of quantification (LOQ) ranged from 0.01-15.20 μg/mL and 0.03-46.06 μg/mL. The method exhibited an intraday and interday precision range of 96.25-105.66% and 93.52-109.92%, respectively (RSD <2.80%). The recoveries and relative standard deviation (RSD) of the four compounds in Tilia amurensis were in the range of 90.42-104.84% and 0.2-2.58%. Conclusion: This developed method was accurate and reliable for the quality evaluation of the four compounds isolated from Tilia amurensis. PMID:25210303

Confirmatory analysis of 17beta-boldenone, 17alpha-boldenone and androsta-1,4-diene-3,17-dione in bovine urine by liquid chromatography-tandem mass spectrometry.

PubMed

Draisci, Rosa; Palleschi, Luca; Ferretti, Emanuele; Lucentini, Luca; delli Quadri, Fernanda

2003-06-15

A sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS-MS) method for confirmatory analysis of 17beta-boldenone (17beta-BOL), 17alpha-boldenone (17alpha-BOL) and androsta-1,4-diene-3,17-dione (ADD) in bovine urine was developed. [2H(2)]17beta-Testosterone (17beta-T-d(2)) was used as the internal standard. Sample preparation involved enzymatic hydrolysis and purification on a C(18) solid-phase extraction column. Chromatographic separation of the analytes was obtained using an RP-C(18) HPLC column. LC-MS-MS detection was carried out with an atmospheric pressure chemical ionisation (APCI) source equipped with a heated nebulizer (HN) interface operating in the positive ion mode. For unambiguous hormone confirmation, three analyte precursor-product ion combinations were monitored during multiple-reaction monitoring (MRM) LC-MS-MS analysis. Overall recovery (%), repeatability (relative standard deviations, RSD, %) and within-laboratory reproducibility (RSD, %) ranged from 92.2 to 97.7%, from 6.50 to 2.94% and from 13.50 to 5.04%, respectively, for all analytes. The limit of quantification in bovine urine was 0.20 ng ml(-1) for 17beta-BOL and ADD and 0.50 ng ml(-1) for 17alpha-BOL. The validated method was successfully applied for determination of 17beta-BOL, 17alpha-BOL and ADD in a large number of bovine urine samples collected within the national Official Residue Control Program.

Simultaneous Determination of Soyasaponins and Isoflavones in Soy (Glycine max L.) Products by HPTLC-densitometry-Multiple Detection.

PubMed

Shawky, Eman; Sallam, Shaimaa M

2017-11-01

A new high-throughput method was developed for the simultaneous analysis of isoflavones and soyasaponnins in Soy (Glycine max L.) products by high-performance thin-layer chromatography with densitometry and multiple detection. Silica gel was used as the stationary phase and ethyl acetate:methanol:water:acetic acid (100:20:16:1, v/v/v/v) as the mobile phase. After chromatographic development, multi-wavelength scanning was carried out by: (i) UV-absorbance measurement at 265 nm for genistin, daidzin and glycitin, (ii) Vis-absorbance measurement at 650 nm for Soyasaponins I and III, after post-chromatographic derivatization with anisaldehyde/sulfuric acid reagent. Validation of the developed method was found to meet the acceptance criteria delineated by ICH guidelines with respect to linearity, accuracy, precision, specificity and robustness. Calibrations were linear with correlation coefficients of >0.994. Intra-day precisions relative standard deviation (RSD)% of all substances in matrix were determined to be between 0.7 and 0.9%, while inter-day precisions (RSD%) ranged between 1.2 and 1.8%. The validated method was successfully applied for determination of the studied analytes in soy-based infant formula and soybean products. The new method compares favorably to other reported methods in being as accurate and precise and in the same time more feasible and cost-effective. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Determination of (2)H-enrichment of rat brain interstitial fluid and rat plasma by headspace-gas-chromatography - quadrupole-mass-spectrometry.

PubMed

Eberl, Anita; Altendorfer-Kroath, Thomas; Kollmann, Denise; Birngruber, Thomas; Sinner, Frank; Raml, Reingard; Magnes, Christoph

2016-09-15

(2)H2O as nonradioactive, stable marker substance is commonly used in preclinical and clinical studies and the precise determination of (2)H2O concentration in biological samples is crucial. However, aside from isotope ratio mass spectrometry (IRMS), only a very limited number of methods to accurately measure the (2)H2O concentration in biological samples are routinely established until now. In this study, we present a straightforward method to accurately measure (2)H-enrichment of rat brain interstitial fluid (ISF) and rat plasma to determine the relative recovery of a cerebral open flow microperfusion (cOFM) probe, using headspace-gas-chromatography - quadrupole-mass-spectrometry. This method is based on basic-catalyzed hydrogen/deuterium exchange in acetone and detects the (2)H-labelled acetone directly by the headspace GC-MS. Small sample volumes and limited number of preparation steps make this method highly competitive. It has been fully validated. (2)H enriched to 8800 ppm in plasma showed an accuracy of 98.9% and %Relative Standard Deviation (RSD) of 3.1 with n = 18 over three days and with two operators. Similar performance was obtained for cerebral ISF enriched to 1100 ppm (accuracy: 96.5%, %RSD: 3.1). With this highly reproducible method we demonstrated the successful employment of (2)H2O as performance marker for a cOFM probe. Copyright © 2016. Published by Elsevier Inc.

Development and validation of an improved method for the determination of chloropropanols in paperboard food packaging by GC-MS.

PubMed

Mezouari, S; Liu, W Yun; Pace, G; Hartman, T G

2015-01-01

The objective of this study was to develop an improved analytical method for the determination of 3-chloro-1,2-propanediol (3-MCPD) and 1,3-dichloropropanol (1,3-DCP) in paper-type food packaging. The established method includes aqueous extraction, matrix spiking of a deuterated surrogate internal standard (3-MCPD-d₅), clean-up using Extrelut solid-phase extraction, derivatisation using a silylation reagent, and GC-MS analysis of the chloropropanols as their corresponding trimethyl silyl ethers. The new method is applicable to food-grade packaging samples using European Commission standard aqueous extraction and aqueous food stimulant migration tests. In this improved method, the derivatisation procedure was optimised; the cost and time of the analysis were reduced by using 10 times less sample, solvents and reagents than in previously described methods. Overall the validation data demonstrate that the method is precise and reliable. The limit of detection (LOD) of the aqueous extract was 0.010 mg kg(-1) (w/w) for both 3-MCPD and 1,3-DCP. Analytical precision had a relative standard deviation (RSD) of 3.36% for 3-MCPD and an RSD of 7.65% for 1,3-DCP. The new method was satisfactorily applied to the analysis of over 100 commercial paperboard packaging samples. The data are being used to guide the product development of a next generation of wet-strength resins with reduced chloropropanol content, and also for risk assessments to calculate the virtual safe dose (VSD).

Development of a method for the simultaneous determination of multi-class pesticides in earthworms by liquid chromatography coupled to tandem electrospray mass spectrometry.

PubMed

Daniele, Gaëlle; Lafay, Florent; Pelosi, Céline; Fritsch, Clémentine; Vulliet, Emmanuelle

2018-06-04

Agricultural intensification, and in particular the use of pesticides, leads over the years to a loss of biodiversity and a decline of ecosystem services in cultivated zones and agricultural landscapes. Among the animal communities involved in the functioning of agro-ecosystems, earthworms are ubiquitous and recognized as indicators of land uses and cultural practices. However, little data is available on the levels of pesticides in such organisms in natura, which would allow estimating their actual exposure and the potentially resulting impacts. Thus, the objective of this study was to develop a sensitive analytical methodology to detect and quantify 27 currently used pesticides in earthworms (Allolobophora chlorotica). A modified QuEChERS extraction was implemented on individual earthworms. This step was followed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The whole analytical method was validated on spiked earthworm blank samples, with regard to linearity (from 1 to 100 method limit of quantification, r 2  > 0.95), intra-day precision (relative standard deviation (RSD) < 15%), inter-day precision (RSD < 20%), recoveries (mainly in the range 70-110%), and limits of detection and of quantification (inferior to 5 ng/g for most of the pesticides). The developed method was successfully applied to determine the concentrations of pesticides in nine individuals collected in natura. Up to five of the selected pesticides have been detected in one individual. Graphical abstract.

Simultaneous determination of gingerols and shogaol using capillary liquid chromatography and its application in discrimination of three ginger varieties from Indonesia.

PubMed

Rafi, Mohamad; Lim, Lee Wah; Takeuchi, Toyohide; Darusman, Latifah Kosim

2013-01-15

A new method using reversed phase capillary liquid chromatography was developed for simultaneous determination of four bioactive compounds found in ginger (Zingiber officinale) namely, 6-, 8-, 10-gingerol, and 6-shogaol. The separation of these four compounds was performed using C30 as the stationary phase and 60% acetonitrile as the mobile phase in isocratic elution mode with a flow rate of 5 μL/min. All four compounds were separated within 25 min with good resolution. As the evaluation of method validation, a linear regression of the four compounds was obtained within the tested range with correlation coefficients ≥ 0.9995. The limits of detection and quantitation were between 0.034-0.039 μg/mL and 0.112-0.129 μg/mL, respectively. Intra- and inter-day precision expressed as relative standard deviations (RSD) were less than 3.1%, and the accuracy based on recovery test was ranging from 97% to 105%. Stability of the analytes within 1 day was found in the range between 1.34% and 2.93% (RSD). In addition, based on the amount of these four compounds combining with the discriminant analysis, a reliable and accurate method was developed for discrimination of three ginger varieties found in Indonesia. The results indicated that the developed method could be used as quality control for ginger raw material and its related products. Copyright © 2012 Elsevier B.V. All rights reserved.

[Correlations between Beck's suicidal ideation scale, suicidal risk assessment scale RSD and Hamilton's depression rating scale].

PubMed

Ducher, J-L; Dalery, J

2008-04-01

Most of the people who will attempt suicide, talk about it beforehand. Therefore, recognition of suicidal risk is not absolutely impossible. Beck's suicidal ideation scale and Ducher's suicidal risk assessment scale (RSD) are common tools to help practicians in this way. These scales and the Hamilton's depression scale were included in an international multicentric, phase IV, double-blind study, according to two parallel groups who had been administered a fixed dose of fluvoxamin or fluoxetin for six weeks. This allowed examination of the correlations between these scales and the relations, which could possibly exist between suicidal risk, depression and anxiety. (a) Relationships between the Beck's suicidal ideation scale, the suicidal risk assessment scale RSD and Hamilton's depression before treatment. Before treatment, the analysis was conducted with 108 male and female depressive outpatients, aged 18 or over. Results revealed a significant positive correlation (with a Pearson's correlation coefficient r equal to 0.69 and risk p<0.0001) between Beck's suicidal ideation scale and the suicidal risk assessment scale RSD. These scales correlate less consistently with Hamilton's depression (Beck/Hamilton's depression: r=0.34; p=0.0004-RSD/Hamilton's depression: r=0.35; p=0.0002). We observed that the clinical anxiety scale by Snaith is also strongly correlated to these two suicidal risk assessment scales (Beck/CAS: r=0.48; p<0.0001-RSD/CAS: r=0.35; p=0.0005). Besides, the item "suicide" of Hamilton's depression scale accounts for more than a third of the variability of Beck's suicidal ideation scale and the suicidal risk assessment scale RSD. According to these results, the suicidal risk evaluated by these two scales seems to be significantly correlated with anxiety as much as with depression. On the other hand, the Clinical Global Impression is fairly significantly correlated with Beck's suicidal ideation scale (r=0.22; p=0.02), unlike the suicidal risk assessment scale RSD (r=0.42; p<0.0001) and Hamilton's depression scale (r=0.58; p<0.0001); (b) Relationships between Beck's suicidal ideation scale, the suicidal risk assessment scale RSD and Hamilton's depression under treatment. The follow-up under treatment (fluvoxamin or fluoxetin) during six weeks revealed the significantly better sensitivity of the RSD in comparison with Beck's suicidal ideation scale and Hamilton's depression scale, showing the significantly faster improvement in the RSD (p<0.0001). There was no significant difference between the evolution of Beck's suicidal ideation scale and Hamilton's depression scale. So, under treatment with fluvoxamin or fluoxetin, the improvement in suicidal risk appears to be as rapid as the improvement in depression. If we look at the treatment prescribed, only the suicidal risk assessment scale RSD revealed a significant difference between the two molecules, with more rapid improvement with fluvoxamin (p=0.015) from D14. In conclusion, the results of this study hypothesize that the suicidal risk, as assessed by Beck's suicidal ideation scale and the suicidal risk assessment scale RSD, appears to be consistently correlated with both the level of anxiety and depression. The study also suggests that all antidepressants may not be equally effective on suicidal risk.

Tire traces - discrimination and classification of pyrolysis-GC/MS profiles.

PubMed

Gueissaz, Line; Massonnet, Geneviève

2013-07-10

Tire traces can be observed on several crime scenes as vehicles are often used by criminals. The tread abrasion on the road, while braking or skidding, leads to the production of small rubber particles which can be collected for comparison purposes. This research focused on the statistical comparison of Py-GC/MS profiles of tire traces and tire treads. The optimisation of the analytical method was carried out using experimental designs. The aim was to determine the best pyrolysis parameters regarding the repeatability of the results. Thus, the pyrolysis factor effect could also be calculated. The pyrolysis temperature was found to be five time more important than time. Finally, a pyrolysis at 650°C during 15s was selected. Ten tires of different manufacturers and models were used for this study. Several samples were collected on each tire, and several replicates were carried out to study the variability within each tire (intravariability). More than eighty compounds were integrated for each analysis and the variability study showed that more than 75% presented a relative standard deviation (RSD) below 5% for the ten tires, thus supporting a low intravariability. The variability between the ten tires (intervariability) presented higher values and the ten most variant compounds had a RSD value above 13%, supporting their high potential of discrimination between the tires tested. Principal Component Analysis (PCA) was able to fully discriminate the ten tires with the help of the first three principal components. The ten tires were finally used to perform braking tests on a racetrack with a vehicle equipped with an anti-lock braking system. The resulting tire traces were adequately collected using sheets of white gelatine. As for tires, the intravariability for the traces was found to be lower than the intervariability. Clustering methods were carried out and the Ward's method based on the squared Euclidean distance was able to correctly group all of the tire traces replicates in the same cluster than the replicates of their corresponding tire. Blind tests on traces were performed and were correctly assigned to their tire source. These results support the hypothesis that the tested tires, of different manufacturers and models, can be discriminated by a statistical comparison of their chemical profiles. The traces were found to be not differentiable from their source but differentiable from all the other tires present in the subset. The results are promising and will be extended on a larger sample set. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Optimisation of an analytical method and results from the inter-laboratory comparison of the migration of regulated substances from food packaging into the new mandatory European Union simulant for dry foodstuffs.

PubMed

Jakubowska, Natalia; Beldì, Giorgia; Peychès Bach, Aurélie; Simoneau, Catherine

2014-01-01

This paper presents the outcome of the development, optimisation and validation at European Union level of an analytical method for using poly(2,6-diphenyl phenylene oxide--PPPO), which is stipulated in Regulation (EU) No. 10/2011, as food simulant E for testing specific migration from plastics into dry foodstuffs. Two methods for fortifying respectively PPPO and a low-density polyethylene (LDPE) film with surrogate substances that are relevant to food contact were developed. A protocol for cleaning the PPPO and an efficient analytical method were developed for the quantification of butylhydroxytoluene (BHT), benzophenone (BP), diisobutylphthalate (DiBP), bis(2-ethylhexyl) adipate (DEHA) and 1,2-cyclohexanedicarboxylic acid, diisononyl ester (DINCH) from PPPO. A protocol for a migration test from plastics using small migration cells was also developed. The method was validated by an inter-laboratory comparison (ILC) with 16 national reference laboratories for food contact materials in the European Union. This allowed for the first time data to be obtained on the precision and laboratory performance of both migration and quantification. The results showed that the validation ILC was successful even when taking into account the complexity of the exercise. The results showed that the method performance was 7-9% repeatability standard deviation (rSD) for most substances (regardless of concentration), with 12% rSD for the high level of BHT and for DiBP at very low levels. The reproducibility standard deviation results for the 16 European Union laboratories were in the range of 20-30% for the quantification from PPPO (for the three levels of concentrations of the five substances) and 15-40% from migration experiments from the fortified plastic at 60°C for 10 days and subsequent quantification. Considering the lack of data previously available in the literature, this work has demonstrated that the validation of a method is possible both for migration from a film and for quantification into a corresponding simulant for specific migration.

Multi-class method for determination of veterinary drug residues and other contaminants in infant formula by ultra performance liquid chromatography-tandem mass spectrometry.

PubMed

Zhan, Jia; Zhong, Ying-ying; Yu, Xue-jun; Peng, Jin-feng; Chen, Shubing; Yin, Ju-yi; Zhang, Jia-Jie; Zhu, Yan

2013-06-01

A rapid, simple and generic analytical method which was able to simultaneously determine 220 undesirable chemical residues in infant formula had been developed. The method comprised of extraction with acetonitrile, clean-up by low temperature and water precipitation, and analysis by ultra performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS-MS) using multiple reaction monitoring (MRM) mode. Most fat materials in acetonitrile extract were eliminated by low temperature clean-up. The water precipitation, providing a necessary and supplementary cleanup, could avoid losses of hydrophobic analytes (avermectins, ionophores). Average recoveries for spiked infant formula were in the range from 57% to 147% with associated RSD values between 1% and 28%. For over 80% of the analytes, the recoveries were between 70% and 120% with RSD values in the range of 1-15%. The limits of quantification (LOQs) were from 0.01 to 5 μg/kg, which were usually sufficient to verify the compliance of products with legal tolerances. Application of this method in routine monitoring programs would imply a drastic reduction of both effort and time. Copyright © 2012 Elsevier Ltd. All rights reserved.

Rapid Quantification of N-Methyl-2-pyrrolidone in Polymer Matrices by Thermal Desorption-GC/MS.

PubMed

Kim, Young-Min; Kim, Jae Woo; Moon, Hye Mi; Lee, Min-Jin; Hosaka, Akihiko; Watanabe, Atsushi; Teramae, Norio; Park, Young-Kwon; Myung, Seung-Woon

2017-01-01

Analysis of a residual solvent in polymeric materials has become an important issue due to the increased regulations and standards for its use. N-Methyl-2-pyrrolidone (NMP) is a solvent widely used in many industries and restricted as one of the chemicals under EU REACH regulations due to its potential harmful effects. In this study, thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) is applied for the quantitative analysis of NMP with the use of a polymer-coated sample cup. By using the polymer-coated sample cup, the vaporization of NMP was prevented during waiting time before TD-GC/MS analysis. The calibration curve for the TD method showed good linearity (correlation coefficient, r 2 = 0.9998) and precision values (below 5.3% RSD). NMP recovery rates in different polymer matrices (PS, PMMA and PVC) were in the range of 98.8 to 106.6% with RSD values below 5.0%. The quantification result (600 mg NMP/kg PVC) for the blind NMP carrying sample in a PVC matrix by TD-GC/MS was higher than that (532 mg NMP/kg PVC) by solvent extraction-GC/MS method.

Simultaneous determination of organophosphorus pesticides in fruits and vegetables using atmospheric pressure gas chromatography quadrupole-time-of-flight mass spectrometry.

PubMed

Cheng, Zhipeng; Dong, Fengshou; Xu, Jun; Liu, Xingang; Wu, Xiaohu; Chen, Zenglong; Pan, Xinglu; Gan, Jay; Zheng, Yongquan

2017-09-15

This paper describes the application of atmospheric pressure gas chromatography quadrupole-time-of-flight mass spectrometry for the simultaneous determination of organophosphorus pesticides in apple, pear, tomato, cucumber and cabbage. Soft ionization with atmospheric pressure ionization source was compared with traditional electron impact ionization (EI). The sensitivity of GC coupled to atmospheric pressure ionization (APGC) for all the analytes was enhanced by 1.0-8.2 times. The ionization modes with atmospheric pressure ionization source was studied by comparing the charge-transfer and proton-transfer conditions. The optimized QuEChERs method was used to pretreat the samples. The calibration curves were found linear from 10 to 1000μg/L, obtaining correlation coefficients higher than 0.9845. Satisfactory mean recovery values, in the range of 70.0-115.9%, and satisfactory precision, with all RSD r <19.7% and all RSD R values <19.5% at the three fortified concentration levels for all the fifteen OPPs. The results demonstrate the potential of APGC-QTOF-MS for routine quantitative analysis of organophosphorus pesticide in fruits and vegetables. Copyright © 2017 Elsevier Ltd. All rights reserved.

An efficient repeating signal detector to investigate earthquake swarms

NASA Astrophysics Data System (ADS)

Skoumal, Robert J.; Brudzinski, Michael R.; Currie, Brian S.

2016-08-01

Repetitive earthquake swarms have been recognized as key signatures in fluid injection induced seismicity, precursors to volcanic eruptions, and slow slip events preceding megathrust earthquakes. We investigate earthquake swarms by developing a Repeating Signal Detector (RSD), a computationally efficient algorithm utilizing agglomerative clustering to identify similar waveforms buried in years of seismic recordings using a single seismometer. Instead of relying on existing earthquake catalogs of larger earthquakes, RSD identifies characteristic repetitive waveforms by rapidly identifying signals of interest above a low signal-to-noise ratio and then grouping based on spectral and time domain characteristics, resulting in dramatically shorter processing time than more exhaustive autocorrelation approaches. We investigate seismicity in four regions using RSD: (1) volcanic seismicity at Mammoth Mountain, California, (2) subduction-related seismicity in Oaxaca, Mexico, (3) induced seismicity in Central Alberta, Canada, and (4) induced seismicity in Harrison County, Ohio. In each case, RSD detects a similar or larger number of earthquakes than existing catalogs created using more time intensive methods. In Harrison County, RSD identifies 18 seismic sequences that correlate temporally and spatially to separate hydraulic fracturing operations, 15 of which were previously unreported. RSD utilizes a single seismometer for earthquake detection which enables seismicity to be quickly identified in poorly instrumented regions at the expense of relying on another method to locate the new detections. Due to the smaller computation overhead and success at distances up to ~50 km, RSD is well suited for real-time detection of low-magnitude earthquake swarms with permanent regional networks.

Impacts of rapeseed dregs on Cd availability in contaminated acid soil and Cd translocation and accumulation in rice plants.

PubMed

Yang, Wen-Tao; Gu, Jiao-Feng; Zou, Jia-Ling; Zhou, Hang; Zeng, Qing-Ru; Liao, Bo-Han

2016-10-01

The objective of the present study was to investigate the effects of rapeseed dregs (RSD, a commonly organic fertilizer in rural China) at application rates of 0, 0.75, 1.5, and 3.0 % on Cd availability in soil and its accumulation in rice plants (Oryza sativa L., Xiangwanxian 12 # , and Weiyou 46 # ) by means of a pot experiment. The results showed that application of RSD resulted in a sharp decrease in the soil TCLP-extractable Cd content. However, the soil TCLP-extractable Cd content in amended soil gradually increased during the rice growing period. Application of RSD significantly increased Cd transport from root to shoot and the amount of Cd accumulated in the aerial part. RSD was an effective organic additive for increasing rice grain yield, but total Cd content in rice grain was also increased. At an application rate of 1.5-3.0 % RSD, the total Cd content in Weiyou 46 # brown rice was 0.27-0.31 mg kg -1 , which exceeded the standard safe limit (0.2 mg kg -1 ) and was also higher than that of Xiangwanxian 12 # (0.04-0.14 mg kg -1 ). Therefore, Weiyou 46 # had a higher dietary risk than Xiangwanxian 12 # with RSD application. We do not recommend planting Weiyou 46 # and applying more than 0.75 % RSD in Cd-contaminated paddy fields.

Simultaneous Determination of Gallic Acid, Ellagic Acid, and Eugenol in Syzygium aromaticum and Verification of Chemical Antagonistic Effect by the Combination with Curcuma aromatica Using Regression Analysis

PubMed Central

Seo, Chang-Seob; Kim, Seong-Sil; Ha, Hyekyung

2013-01-01

This study was designed to perform simultaneous determination of three reference compounds in Syzygium aromaticum (SA), gallic acid, ellagic acid, and eugenol, and to investigate the chemical antagonistic effect when combining Curcuma aromatica (CA) with SA, based on chromatographic analysis. The values of LODs and LOQs were 0.01–0.11 μg/mL and 0.03–0.36 μg/mL, respectively. The intraday and interday precisions were <3.0 of RSD values, and the recovery was in the range of 92.19–103.24%, with RSD values <3.0%. Repeatability and stability were 0.38–0.73% and 0.49–2.24%, respectively. Compared with the content of reference and relative peaks in SA and SA combined with CA (SAC), the amounts of gallic acid and eugenol were increased, while that of ellagic acid was decreased in SAC (compared with SA), and most of peak areas in SA were reduced in SAC. Regression analysis of the relative peak areas between SA and SAC showed r 2 values >0.87, indicating a linear relationship between SA and SAC. These results demonstrate that the components contained in CA could affect the extraction of components of SA mainly in a decreasing manner. The antagonistic effect of CA on SA was verified by chemical analysis. PMID:23878761

Analytical parameters of the microplate-based ORAC-pyrogallol red assay.

PubMed

Ortiz, Rocío; Antilén, Mónica; Speisky, Hernán; Aliaga, Margarita E; López-Alarcón, Camilo

2011-01-01

The analytical parameters of the microplate-based oxygen radicals absorbance capacity (ORAC) method using pyrogallol red (PGR) as probe (ORAC-PGR) are presented. In addition, the antioxidant capacity of commercial beverages, such as wines, fruit juices, and iced teas, is estimated. A good linearity of the area under the curve (AUC) versus Trolox concentration plots was obtained [AUC = (845 +/- 110) + (23 +/- 2) [Trolox, microM], R = 0.9961, n = 19]. QC experiments showed better precision and accuracy at the highest Trolox concentration (40 microM) with RSD and REC (recuperation) values of 1.7 and 101.0%, respectively. When red wine was used as sample, the method also showed good linearity [AUC = (787 +/- 77) + (690 +/- 60) [red wine, microL/mL]; R = 0.9926, n = 17], precision and accuracy with RSD values from 1.4 to 8.3%, and REC values that ranged from 89.7 to 103.8%. Additivity assays using solutions containing gallic acid and Trolox (or red wine) showed an additive protection of PGR given by the samples. Red wines showed higher ORAC-PGR values than white wines, while the ORAC-PGR index of fruit juices and iced teas presented a great variability, ranging from 0.6 to 21.6 mM of Trolox equivalents. This variability was also observed for juices of the same fruit, showing the influence of the brand on the ORAC-PGR index. The ORAC-PGR methodology can be applied in a microplate reader with good linearity, precision, and accuracy.

Renal sympathetic denervation alleviates myocardial fibrosis following isoproterenol-induced heart failure.

PubMed

Wang, Neng; Zheng, Xiaoxin; Qian, Jin; Yao, Wei; Bai, Lu; Hou, Guo; Qiu, Xuan; Li, Xiaoyan; Jiang, Xuejun

2017-10-01

The aim of the present study was to determine if renal sympathetic denervation (RSD) may alleviate isoproterenol-induced left ventricle remodeling, and to identify the underlying mechanism. A total of 70 rats were randomly divided into control (n=15), sham operation (n=15), heart failure (HF) with sham operation (HF + sham; n=20) and HF with treatment (HF + RSD; n=20) groups. The HF model was established by subcutaneous injection of isoproterenol; six weeks later, 1eft ventricular internal diameter at end‑systole (LVIDs), left ventricular systolic posterior wall thickness (LVPWs), 1eft ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) were measured. Plasma norepinephrine (NE), angiotensin II (Ang II) and aldosterone (ALD) levels were measured by ELISA. Myocardial collagen volume fraction (CVF) was determined by Masson's staining. Reverse transcription‑quantitative polymerase chain reaction was used to determine the mRNA expression levels of ventricular transforming growth factor‑β (TGF‑β), connective tissue growth factor (CTGF) and microRNAs (miRs), including miR‑29b, miR‑30c and miR‑133a. The results demonstrated that LVIDs and LVPWs in the HF + RSD group were significantly decreased compared with the HF + sham group. By contrast, LVFS and LVEF in the HF + RSD group were significantly increased compared with the HF + sham group. RSD significantly reduced the levels of plasma NE, Ang II and ALD. CVF in the HF + RSD group was reduced by 38.1% compared with the HF + sham group. Expression levels of TGF‑β and CTGF were decreased, whereas those of miR‑29b, miR‑30c and miR‑133a were increased, in the HF + RSD group compared with the HF + sham group. These results indicated that RSD alleviates isoproterenol‑induced left ventricle remodeling potentially via downregulation of TGF‑β/CTGF and upregulation of miR‑29b, miR‑30c and miR‑133a. RSD may therefore be an effective non‑drug therapy for the treatment of heart failure.

Renal sympathetic denervation alleviates myocardial fibrosis following isoproterenol-induced heart failure

PubMed Central

Wang, Neng; Zheng, Xiaoxin; Qian, Jin; Yao, Wei; Bai, Lu; Hou, Guo; Qiu, Xuan; Li, Xiaoyan; Jiang, Xuejun

2017-01-01

The aim of the present study was to determine if renal sympathetic denervation (RSD) may alleviate isoproterenol-induced left ventricle remodeling, and to identify the underlying mechanism. A total of 70 rats were randomly divided into control (n=15), sham operation (n=15), heart failure (HF) with sham operation (HF + sham; n=20) and HF with treatment (HF + RSD; n=20) groups. The HF model was established by subcutaneous injection of isoproterenol; six weeks later, 1eft ventricular internal diameter at end-systole (LVIDs), left ventricular systolic posterior wall thickness (LVPWs), 1eft ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) were measured. Plasma norepinephrine (NE), angiotensin II (Ang II) and aldosterone (ALD) levels were measured by ELISA. Myocardial collagen volume fraction (CVF) was determined by Masson's staining. Reverse transcription-quantitative polymerase chain reaction was used to determine the mRNA expression levels of ventricular transforming growth factor-β (TGF-β), connective tissue growth factor (CTGF) and microRNAs (miRs), including miR-29b, miR-30c and miR-133a. The results demonstrated that LVIDs and LVPWs in the HF + RSD group were significantly decreased compared with the HF + sham group. By contrast, LVFS and LVEF in the HF + RSD group were significantly increased compared with the HF + sham group. RSD significantly reduced the levels of plasma NE, Ang II and ALD. CVF in the HF + RSD group was reduced by 38.1% compared with the HF + sham group. Expression levels of TGF-β and CTGF were decreased, whereas those of miR-29b, miR-30c and miR-133a were increased, in the HF + RSD group compared with the HF + sham group. These results indicated that RSD alleviates isoproterenol-induced left ventricle remodeling potentially via downregulation of TGF-β/CTGF and upregulation of miR-29b, miR-30c and miR-133a. RSD may therefore be an effective non-drug therapy for the treatment of heart failure. PMID:28849013

Qualitative and quantitative measurement of cannabinoids in cannabis using modified HPLC/DAD method.

PubMed

Patel, Bhupendra; Wene, Daniel; Fan, Zhihua Tina

2017-11-30

This study presents an accurate and high throughput method for the quantitative determination of various cannabinoids in cannabis plant material using high pressure liquid chromatography (HPLC) with a diode array detector (DAD). Sample extraction and chromatographic analysis conditions for the measurement of cannabinoids in the complex cannabis plant material matrix were optimized. The Agilent Poroshell 120 SB-C18 column provided high resolution for all target analytes with a short run time (10minutes) given the core shell technology. The aqueous buffer mobile phase was optimized with ammonium acetate at pH 4.75. The change in the mobile phase and the new column ensured a separation between cannabidiol (CBD and cannabigerol (CBG) along with cannabigerol and tetrahydrocannabinolic acid (THCA), which were not well separated by previous publications, improved buffering capacity, and provided analytical performance stability. Moreover, baseline drifting was significantly minimized by the use of a low concentration buffer solution (25mM ammonium acetate). In addition, evaporation and reconstitution of the sample residue with a methanol-organic pure (OP) water solution (65:35) significantly reduced the matrix interference. The modified extraction produced good recoveries (>91%) for each of the eight cannabinoids. The optimized method was validated for specificity, linearity, sensitivity, precision, accuracy, and stability. The combined relative standard deviation (%RSD) for intra-day and inter-day precision for all eight analytes varied from 2.5% to 5.2% and 0.28% to 5.5%, respectively. The %RSD for the repeatability study varied from 1.1% to 5.5%. The recoveries from spiked cannabis matrix samples were greater than 90% for all analytes, except delta-8-tetrahydrocannabinol (Δ 8 -THC), which was 80%. The recoveries varied from 81% to 107% with a precision of 0.7-8.1%RSD. Delta-9-tetrahydrocannabinol (Δ 9 -THC) in all of the cannabis samples (n=635) was less than 10%, which is in compliance with the NJ Medicinal Marijuana regulation. Analysis of samples from two cultivars, which included ten individual samples, four composite samples, seven calibration standards, and four quality control standards, can be performed within 24hours by this high throughput method. Published by Elsevier B.V.

Possible mechanism by which renal sympathetic denervation improves left ventricular remodelling after myocardial infarction.

PubMed

Zheng, Xiao-Xin; Li, Xiao-Yan; Lyu, Yong-Nan; He, Yi-Yu; Wan, Wei-Guo; Zhu, Hong-Ling; Jiang, Xue-Jun

2016-02-01

What is the central question of this study? The enzyme system that is responsible for extracellular matrix (ECM) turnover is the matrix metalloproteinases (MMPs), which can be blocked by the tissue inhibitors of MMPs (TIMPs). Whether renal sympathetic denervation (RSD) is able to ameliorate post-myocardial infarction left ventricular remodelling through attenuation of ECM via regulation of MMP activity and/or the MMP-TIMP complex remains unknown. What is the main finding and its importance? Renal sympathetic denervation has therapeutic effects on post-myocardial infarction left ventricular remodelling, probably by attenuating the ECM through regulation of the MMP9-TIMP1 complex in the transforming growth factor-β1 (a profibrotic cytokine that accelerates ECM remodelling after ischaemia) signalling pathway. Whether renal sympathetic denervation (RSD) is able to ameliorate post-myocardial infarction (post-MI) left ventricular (LV) remodelling by attenuation of the extracellular matrix via regulation of matrix metalloproteinase (MMP) activity and/or the MMP-tissue inhibitor of matrix metalloproteinase (TIMP) complex remains unknown. Sixty-five Sprague-Dawley rats were randomly divided into the following four groups: normal (N, n = 15), RSD (RSD, n = 15), myocardial infarction (MI, n = 15) and RSD 3 days after MI (MI3d+RSD, n = 20). The bilateral renal nerves were surgically denervated 3 days after MI had been induced by coronary artery ligation. Left ventricular function was assessed using echocardiography and a Millar catheter at 6 weeks post-MI. Plasma noradrenaline, angiotensin II and aldosterone, collagen volume fraction, transforming growth factor-β1 (TGF-β1), MMP2, MMP9 and TIMP1 in heart tissue were measured 6 weeks after MI. In rats with MI3d+RSD compared with MI rats, RSD improved systolic and diastolic function, resulting in an improvement in ejection fraction (P < 0.05), fractional shortening (P < 0.05) and LV internal dimension in systole (P < 0.05) and diastole (P < 0.05). Additionally, RSD treatment decreased left ventricular end-diastolic pressure (P < 0.05) and increased LV systolic pressure (P < 0.05) and maximal and minimal rate of LV pressure (both P < 0.05). Meanwhile, RSD reduced collagen content (P < 0.01). TIMP1 was upregulated (P < 0.05), whereas MMP2, MMP9 and TGF-β1 were downregulated in the LV of RSD-treated animals (P < 0.05). Renal sympathetic denervation has therapeutic effects on post-MI LV remodelling, probably owing to effects on the extracellular matrix by regulation of the MMP9-TIMP1 balance in the TGF-β1 signalling pathway. Renal sympathetic denervation may be considered as a non-pharmacological approach for the improvement of post-MI cardiac dysfunction. © 2015 The Authors. Experimental Physiology © 2015 The Physiological Society.

Analysis of drug content and weight uniformity for half-tablets of 6 commonly split medications.

PubMed

Hill, Shaynan W; Varker, Andrew S; Karlage, Kelly; Myrdal, Paul B

2009-04-01

Cost savings can be achieved with the practice of tablet splitting. Previous research has shown weight nonuniformity within tablet halves. However, limited research to date has found that the potential dose inaccuracy resulting from splitting tablets does not significantly affect clinical outcomes. To determine the drug content and weight in split half-tablets of 6 commonly split medications using drug assay analysis. This study was performed by 2 fourth-year pharmacy students using 30 randomly selected tablets of each of the following 6 medications: warfarin sodium 5 milligrams (mg), simvastatin 80 mg, metoprolol succinate 200 mg, metoprolol tartrate 25 mg, citalopram 40 mg, and lisinopril 40 mg. A randomly selected half of the tablets were split by a single pharmacy student using a tablet cutter, and the remaining tablets were kept whole. Drug content was analyzed for 15 whole tablets and 30 half-tablets for each of the 6 drugs using high performance liquid chromatography, an analytical tool used to identify and quantify substances in solution. Drug content uniformity was assessed by comparing drug content within half-tablets with one-half of the drug content mean found for all whole tablets in the sample. Weight uniformity was assessed by comparing half-tablet weights, as determined by a Mettler analytical balance, with one-half of the mean weight for whole tablets in the sample. The percentages by which each whole tablet's or half-tablet's drug content and weight differed from sample mean values were compared with proxy United States Pharmacopeia (USP) specification ranges for drug content (95%-105% for warfarin sodium and 90%-110% for the other 5 drugs). Additionally, these outcomes were compared for nonscored versus scored tablets. The percent relative standard deviation (%RSD, ratio of the standard deviation to the mean), a commonly used measure of the repeatability and precision of assays used to analyze drug content, was also calculated in order to determine whether the drugs met proxy USP specification for %RSD (less than 6% for all drugs studied). A total of 43 of 180 half-tablets (23.9%) differed from sample mean values by a percentage that fell outside of proxy USP specification for drug content; warfarin sodium (11 of 30 half-tablets, 36.7%), simvastatin (3 of 30 half-tablets, 10.0%) metoprolol succinate (10 of 30 half-tablets, 33.3%), metoprolol tartrate (4 of 30 half-tablets, 13.3%), citalopram (5 of 30 half-tablets, 16.7%), and lisinopril (10 of 30 half-tablets, 33.3%). Half-tablets outside of proxy USP specification for weight included warfarin sodium (10 of 30 half-tablets, 33.3%), metoprolol succinate (6 of 30 half-tablets, 20%), and lisinopril (7 of 30 half-tablets, 23.3%). The %RSDs for drug content and weight fell outside of the proxy USP specification for %RSD for metoprolol succinate (drug content = 8.98%, weight = 7.70%) and lisinopril (drug content = 10.41%, weight = 8.13%). Mean percent weight loss after splitting was less than 1% for all drugs except lisinopril, which had an average weight loss of 1.25%. The total numbers of scored (nonscored) tablet halves that fell outside of proxy USP specification were 20 (23) for drug content and 10 (13) for weight. When measuring drug content, the numbers of out-of-range half-tablets for scored (nonscored) drugs were 36 (44) at 95%-105%, 9 (23) at 90%-110%, 0 (10) at 85%-115%, and 0 (1) at 75%-125%. When measuring weight, the numbers of out-of-range half-tablets for scored (nonscored) drugs were 28 (38) at 95%-105%, 0 (14) at 90%-110%, 0 (3) at 85%-115%, and 0 (0) at 75%-125%. Dose variation exceeded a proxy USP specification for more than one-third of sampled half-tablets of warfarin sodium, metoprolol succinate, and lisinopril and appeared to be greater for nonscored tablets as compared with scored tablets. Drug content variation in half-tablets appeared to be attributable primarily to weight variation occurring when tablets powder or fragment during the splitting process. Therefore, equal daily doses will be determined by the ability of patients to split tablets perfectly in half.

Sol-gel electrospinning preparation of hybrid carbon silica nanofibers for extracting organophosphorus pesticides prior to analyzing them by gas chromatography-ion mobility spectrometry.

PubMed

Jafari, Mohammad T; Saraji, Mohammad; Kermani, Mansoure

2018-07-13

Carbon-silica hybrid nanofibers as high performance coatings for solid-phase microextraction fibers were used for analyzing some pesticides by using gas chromatography-corona discharge ion mobility spectrometry. To that end, the fibers were prepared by carbonizing sol-gel based on electrospun polyacrylonitrile and tetraethyl orthosilicate nanofibers as carbon and silica precursors, respectively. Different parameters affecting the electrospinning and the extraction processes including spinning distance, voltage, feeding rate, stirring rate, salt concentration, temperature and extraction time were optimized by response surface methodology. The method involved deionized water samples spiked with pesticides at different concentration levels. The calibration curves were linear in the ranges of 0.1-20 and 0.05-20 μg L -1 with determination coefficients (R 2 ) of 0.9976 and 0.9928 for malathion and chlorpyrifos, respectively. The limits of detection of 0.032 and 0.019 μg L -1 and the limits of quantification of 0.1 and 0.05 μg L -1 were found for malathion and chlorpyrifos, respectively. Acceptable reproducibility values were obtained with relative standard deviations (RSD, n = 3) lower than 6 and 15%, for intra-day and inter-day precision, respectively. Finally, the relative recoveries of the proposed method were calculated in the range of 80-111% for real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

A sustainable on-line CapLC method for quantifying antifouling agents like irgarol-1051 and diuron in water samples: Estimation of the carbon footprint.

PubMed

Pla-Tolós, J; Serra-Mora, P; Hakobyan, L; Molins-Legua, C; Moliner-Martinez, Y; Campins-Falcó, P

2016-11-01

In this work, in-tube solid phase microextraction (in-tube SPME) coupled to capillary LC (CapLC) with diode array detection has been reported, for on-line extraction and enrichment of booster biocides (irgarol-1051 and diuron) included in Water Frame Directive 2013/39/UE (WFD). The analytical performance has been successfully demonstrated. Furthermore, in the present work, the environmental friendliness of the procedure has been quantified by means of the implementation of the carbon footprint calculation of the analytical procedure and the comparison with other methodologies previously reported. Under the optimum conditions, the method presents good linearity over the range assayed, 0.05-10μg/L for irgarol-1051 and 0.7-10μg/L for diuron. The LODs were 0.015μg/L and 0.2μg/L for irgarol-1051 and diuron, respectively. Precision was also satisfactory (relative standard deviation, RSD<3.5%). The proposed methodology was applied to monitor water samples, taking into account the EQS standards for these compounds. The carbon footprint values for the proposed procedure consolidate the operational efficiency (analytical and environmental performance) of in-tube SPME-CapLC-DAD, in general, and in particular for determining irgarol-1051 and diuron in water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Multianalyte imaging in one-shot format sensors for natural waters.

PubMed

Lapresta-Fernández, A; Huertas, Rafael; Melgosa, Manuel; Capitán-Vallvey, L F

2009-03-23

A one-shot multisensor based on ionophore-chromoionophore chemistry for optical monitoring of potassium, magnesium and hardness in water is presented. The analytical procedure uses a black and white non-cooled CCD camera for image acquisition of the one-shot multisensor after reaction, followed by data treatment for quantitation using the grey value pixel average from a defined region of interest from each sensing area to build the analytical parameter 1-alpha. In optimised experimental conditions, the procedure shows a large linear range, up to 6 orders using the linearised model and good detection limits: 9.92 x 10(-5)mM, 1.86 x 10(-3)mM and 1.30 x 10(-2)mgL(-1) of CaCO(3) for potassium, magnesium and hardness, respectively. This analysis system exhibits good precision in terms of relative standard deviation (RSD%) from 2.3 to 3.8 for potassium, from 5.0 to 6.8 for magnesium and from 5.4 to 5.9 for hardness. The trueness of this multisensor procedure was demonstrated comparing it with results obtained by a DAD spectrophotometer used as a reference. Finally, it was satisfactorily applied to the analysis of these analytes in miscellaneous samples, such as water and beverage samples from different origins, validating the results against atomic absorption spectrometry (AAS) as the reference procedure.

Development and optimization of a reversed-phase high-performance liquid chromatographic method for the determination of acetaminophen and its major metabolites in rabbit plasma and urine after a toxic dose.

PubMed

Vertzoni, M V; Archontaki, H A; Galanopoulou, P

2003-07-14

A reversed-phase high-performance liquid chromatographic method with detection at 242 nm was developed, optimized and validated for the determination of acetaminophen (A) and its major metabolites glucuronide (AG) and sulfate (AS) conjugates in rabbit plasma and urine after a toxic dose. m-Aminophenol was used as internal standard (IS). A Hypersil BDS RP-C18 column (250 x 4.6 mm), 5 microm particle size, was equilibrated with a mobile phase composed of aqueous buffer solution of KH2PO4 0.05 M containing 1% CH3COOH (pH 6.5) and methanol (95:5, v/v). Its flow rate was 1.5 ml/min. Calibration curves of A, AG and AS were linear in the concentration ranges of 0.5-250, 1-200, 0.5-100 microg/ml in plasma and 1-200, 0.5-150, 0.5-100 microg/ml in urine matrix, respectively. Limits of detection and quantitation were calculated in all cases and extensive recovery studies were also performed. Intra-day relative standard deviation (R.S.D.) for A, AG and AS in plasma was less than 5, 4, 2% and in urine less than 4, 7, 4%, respectively, while the corresponding inter-day values were 7, 6, 4% and 5, 8, 6%, respectively.

Magnetic solid-phase extraction using nanoporous three dimensional graphene hybrid materials for high-capacity enrichment and simultaneous detection of nine bisphenol analogs from water sample.

PubMed

Wang, Lingling; Zhang, Zhenzhen; Zhang, Jing; Zhang, Lei

2016-09-09

The synthesis of a magnetic nanoporous three dimensional graphene (3DG)/ZnFe2O4 composite has been achieved. Through formation of graphene hydrogel, ZnFe2O4 magnetic particles was successfully introduced into the nanoporous 3DG, resulting in a magnetic porous carbon material. The morphology, structure, and magnetic behavior of the as-prepared 3DG/ZnFe2O4 were characterized by using the techniques of SEM, XRD, BET, VSM, FTIR, Raman and TGA. The 3DG/ZnFe2O4 has a high specific surface area and super paramagnetism. Its performance was evaluated by the magnetic solid-phase extraction of nine bisphenol analogs (BPs) from water samples followed by HPLC analysis, and showed excellent adsorption capability for the nine target compounds. Under optimized condition, the lower method detection limits (0.05-0.18ngmL(-1)), the higher enrichment factors (800 fold) and good recoveries (95.1-103.8%) with relative standard deviation (RSD) values less than 6.2% were achieved. The results indicated that the developed method based on the use of 3DG/ZnFe2O4 as the magnetic adsorbent has the advantages of convenience and high efficiency, and can be successfully applied to detect the nine BPs in real water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Highly crosslinked polymeric monoliths for reversed-phase capillary liquid chromatography of small molecules.

PubMed

Liu, Kun; Tolley, H Dennis; Lee, Milton L

2012-03-02

Seven crosslinking monomers, i.e., 1,3-butanediol dimethacrylate (1,3-BDDMA), 1,4-butanediol dimethacrylate (1,4-BDDMA), neopentyl glycol dimethacrylate (NPGDMA), 1,5-pentanediol dimethacrylate (1,5-PDDMA), 1,6-hexanediol dimethacrylate (1,6-HDDMA), 1,10-decanediol dimethacrylate (1,10-DDDMA), and 1,12-dodecanediol dimethacrylate (1,12-DoDDMA), were used to synthesize highly cross-linked monolithic capillary columns for reversed-phase liquid chromatography (RPLC) of small molecules. Dodecanol and methanol were chosen as "good" and "poor" porogenic solvents, respectively, for these monoliths, and were investigated in detail to provide insight into the selection of porogen concentration using 1,12-DoDDMA. Isocratic elution of alkylbenzenes at a flow rate of 300 nL/min was conducted for all of the monoliths. Gradient elution of alkylbenzenes and alkylparabens provided high resolution separations. Optimized monoliths synthesized from all seven crosslinking monomers showed high permeability. Several of the monoliths demonstrated column efficiencies in excess of 50,000 plates/m. Monoliths with longer alkyl-bridging chains showed very little shrinking or swelling in solvents of different polarities. Column preparation was highly reproducible; the relative standard deviation (RSD) values (n=3) for run-to-run and column-to-column were less than 0.25% and 1.20%, respectively, based on retention times of alkylbenzenes. Copyright © 2012 Elsevier B.V. All rights reserved.

Direct analysis of human breath ammonia using corona discharge ion mobility spectrometry.

PubMed

Jazan, Elham; Mirzaei, Hadi

2014-01-01

In this study, ammonia in human breath was directly determined using corona discharge ionization ion mobility spectrometry (CD-IMS) technique with several important advantages including high sensitivity, low cost, high speed, and ease of maintenance. The temperature effect on the ammonia signal was evaluated too. The results indicated that the best temperature for the investigation of breath ammonia was 150°C. The analytical results showed that the linear dynamic range was between 12 and 810ppb and the detection limit was 6.6ppb. The relative standard deviation (RSD) was obtained to be 5, 3, and 3 for 290, 348, and 522ppb, respectively. The amounts of ammonia in breath of eight healthy volunteers were measured. The values were between 236 and 1218ppb. Also, the inequality in breath ammonia levels was scrutinized over a 6h working day for three healthy volunteers. The results showed a drop in breath ammonia from the morning amount to the mid-day measurement and then, a progressive increase while the day continued. In addition, the amounts of ammonia were determined to be 1494-1553ppb in exhaled breath of two renal failure patients. The results obtained in this work revealed that the method was conveniently established without any considerable sample pretreatment for direct analysis of ammonia in human breath. Copyright © 2013 Elsevier B.V. All rights reserved.

[Determination of Fe, Ti and V in vanadium and titanium magnetite by ICP-OES and microwave-assisted digestion].

PubMed

Zhu, Xia-ping; Yin, Ji-xian; Chen, Wei-dong; Hu, Zi-Wen; Liang, Qing-xun; Chen, Tie-yao

2010-08-01

The method of determination of iron, titanium and vanadium in indissolvable vanadium and titanium magnetite has been established by inductively coupled plasma atomic emission spectroscopy through adding the complexant A and using microwave-assisted digestion. The optimal conditions are confirmed by orthogonal experiment: 0.1 g vanadium and titanium magnetite, 0.04 g complexant A, 12 mL concentrated HC1, 10 min digestion time, and 385 W microwave power. The newly-established method has been applied to digest vanadium and titanium magnetite of Panzhihua Iron and Steel Institute (GBW07226). The iron, titanium and vanadium were detected by ICP-OES, and both comparative error (Er%) and comparative standard deviation (RSD%) met the demand of analytical chemistry, and the complexant A can significantly accelerate the dissolution of vanadium and titanium magnetite through the complexation with the dissolved metal ions, and making the surface of sample and hydrochloric acid medium to update constantly. The determination of the main and trace elements of digestion solution at the same time was achieved by ICP-OES. The method has the advantages of less use of reagents, economy, rapidness, and being friendly to environment, and it meets the requirement for rapid and volume determination. So the method has the value of practical application for the entry-exit inspection and quarantine department of the state and other relevant inspection units.

Ultrasound-assisted dispersive magnetic solid phase extraction for preconcentration and determination of trace amount of Hg (II) ions from food samples and aqueous solution by magnetic graphene oxide (Fe3O4@GO/2-PTSC): Central composite design optimization.

PubMed

Keramat, Akram; Zare-Dorabei, Rouholah

2017-09-01

In this work, the synthesis of the magnetic graphene oxide modified by 2-pyridinecarboxaldehyde thiosemicarbazone groups (Fe 3 O 4 @GO/2-PTSC) was utilized for preconcentration and determination of mercuric ions in a trace amount by inductively coupled plasma-optical emission spectrometry (ICP-OES). Characterization of the adsorbent was performed using various techniques, such as FT-IR, VSM, SEM and XRD analysis. Central composite design (CCD) under response surface methodology (RSM) was used for obtaining the most important parameters and probable interactions in variables. The variables such as adsorbent dosage, pH, desorption time, and eluent volume was optimized. These values were 8mg, 5.4min, 0.5mL (HCl, 0.1M), respectively. Sonication had an important role in shortening the adsorption time of Hg (II) ions by enhancing the dispersion of adsorbent in solution. Under the optimal conditions, the proposed method presented high enrichment factor of 193, an extraction percentage of 96.5, a detection limit of 0.0079µgL -1 and a relative standard deviation (RSD %) of 1.63%. Finally, the application of the synthesized material was evaluated for preconcentration and determination of mercuric ions from foods and environmental waters samples. Copyright © 2017 Elsevier B.V. All rights reserved.

A digital PCR method for identifying and quantifying adulteration of meat species in raw and processed food

PubMed Central

Ren, Junan; Deng, Tingting; Huang, Wensheng; Chen, Ying; Ge, Yiqiang

2017-01-01

Meat adulteration is a worldwide concern. In this paper, a new droplet digital PCR (ddPCR) method was developed for the quantitative determination of the presence of chicken in sheep and goat meat products. Meanwhile, a constant (multiplication factor) was introduced to transform the ratio of copy numbers to the proportion of meats. The presented ddPCR method was also proved to be more accurate (showing bias of less than 9% in the range from 5% to 80%) than real-time PCR, which has been widely used in this determination. The method exhibited good repeatability and stability in different thermal treatments and at ultra-high pressure. The relative standard deviation (RSD) values of 5% chicken content was less than 5.4% for ultra-high pressure or heat treatment. Moreover, we confirmed that different parts of meat had no effect on quantification accuracy of the ddPCR method. In contrast to real-time PCR, we examined the performance of ddPCR as a more precise, sensitive and stable analytical strategy to overcome potential problems of discrepancies in amplification efficiency discrepancy and to obtain the copy numbers directly without standard curves. The method and strategy developed in this study can be applied to quantify the presence and to confirm the absence of adulterants not only to sheep but also to other kinds of meat and meat products. PMID:28319152

Halloysite nanotubes as a solid sorbent in ultrasound-assisted dispersive micro solid-phase extraction for the determination of bismuth in water samples using high-resolution continuum source graphite-furnace atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Krawczyk-Coda, Magdalena

2017-03-01

In this research, a simple, accurate, and inexpensive preconcentration procedure was developed for the determination of bismuth in water samples, using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR CS GFAAS). During the preconcentration step, halloysite nanotubes (HNTs) were used as a solid sorbent in ultrasound-assisted dispersive micro solid-phase extraction (USA DMSPE). The influence of the pH of the sample solution, amount of HNTs, and extraction time, as well as of the main parameters of HR CS GFAAS, on absorbance was investigated. The limit of detection was 0.005 μg L- 1. The preconcentration factor achieved for bismuth was 32. The relative standard deviation (RSD) was 4%. The accuracy of this method was validated by analyses of NIST SRM 1643e (Trace elements in water) and TMDA-54.5 (A high level fortified sample for trace elements) certified reference materials. The measured bismuth contents in these certified reference materials were in satisfactory agreement with the certified values according to the t-test for a 95% confidence level. The proposed method has been successfully applied to the determination of bismuth in five different real water samples (seawater, lake water, river water, stream water and rain water).

[Determination of thyreostats in bovine urine using ultra-high performance liquid chromatography-tandem mass spectrometry].

PubMed

Lech, Rodziewicz; Jolanta, MasŁOwiecka; Anna, Sadowska; Halina, Car

2017-10-08

Five thyreostats (TSs), namely tapazole, thiouracil, methylthiouracil, propylthiouracil, and phenylthiouracil, were determined in bovine urine using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in positive electrospray ionization mode. Extraction and clean-up were achieved using a ChemElut cartridge with tert -butyl methyl ether, without a derivatization step. Separation was achieved on an Acquity UPLC SS T3 column. The mobile phase was acetonitrile and water containing 0.2% (v/v) formic acid. The mass spectrometer was operated in multiple reaction monitoring mode. Urine samples were spiked with TS solution at levels corresponding to 5, 10, 15, and 20 μg/L. The accuracy (internal standard corrected) ranged from 92% to 107%, with a repeatability precision (relative standard deviation, RSD) less than 15% for all five analytes. The RSDs within-laboratory reproducibility was less than 26%. The decision limits (CCα) and detection capabilities (CCβ) were obtained from a calibration curve and were in the ranges of 3.1-6.1 μg/L and 4.0-7.4 μg/L, respectively. The CCα and CCβ values were below the recommended concentration, which was set at 10 μg/L. The results show that the described method is suitable for the direct detection of TSs in bovine urine. This method can also be used to determine TSs in porcine urine.

A colorimetric probe based on desensitized ionene-stabilized gold nanoparticles for single-step test for sulfate ions.

PubMed

Arkhipova, Viktoriya V; Apyari, Vladimir V; Dmitrienko, Stanislava G

2015-03-15

Desensitized ionene-stabilized gold nanoparticles have been prepared and applied as a colorimetric probe for the single-step test for sulfate ions at the relatively high concentration level. The approach is based on aggregation of the nanoparticles leading to the change in absorption spectra and color of the solution. These nanoparticles are characterized by the decreased sensitivity due to both electrostatic and steric stabilization, which allows for simple, and rapid direct single-step determination of sulfate at the relatively high concentration level in real water samples without sample pretreatment or dilution. Influence of different factors (the time of interaction, pH, the concentrations of sulfate ions and the nanoparticles) on the aggregation and analytical performance of the procedure was investigated. The method allows for the determination of sulfate ions in the mass range of 0.2-0.4 mg with RSD of 5% from the sample volume of less than 2 mL. It has a sharp dependence of the colorimetric response on the concentration of sulfate, which makes it prospective for indicating deviations of the sulfate concentration regarding some declared value chosen within the above range. The time of the analysis is 2 min. The method was applied to the analysis of mineral water samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Inductively coupled plasma atomic fluorescence spectrometric determination of cadmium, copper, iron, lead, manganese and zinc

USGS Publications Warehouse

Sanzolone, R.F.

1986-01-01

An inductively coupled plasma atomic fluorescence spectrometric method is described for the determination of six elements in a variety of geological materials. Sixteen reference materials are analysed by this technique to demonstrate its use in geochemical exploration. Samples are decomposed with nitric, hydrofluoric and hydrochloric acids, and the residue dissolved in hydrochloric acid and diluted to volume. The elements are determined in two groups based on compatibility of instrument operating conditions and consideration of crustal abundance levels. Cadmium, Cu, Pb and Zn are determined as a group in the 50-ml sample solution under one set of instrument conditions with the use of scatter correction. Limitations of the scatter correction technique used with the fluorescence instrument are discussed. Iron and Mn are determined together using another set of instrumental conditions on a 1-50 dilution of the sample solution without the use of scatter correction. The ranges of concentration (??g g-1) of these elements in the sample that can be determined are: Cd, 0.3-500; Cu, 0.4-500; Fe, 85-250 000; Mn, 45-100 000; Pb, 5-10 000; and Zn, 0.4-300. The precision of the method is usually less than 5% relative standard deviation (RSD) over a wide concentration range and acceptable accuracy is shown by the agreement between values obtained and those recommended for the reference materials.

Development of a laser ablation-hollow cathode glow discharge emission source and the application to the analysis of steel samples.

PubMed

Naeem, Tariq M; Matsuta, Hideyuki; Wagatsuma, Kazuaki

2004-12-01

A novel atomic emission spectrometry comprising laser ablation as a sampling source and hollow cathode plasma for the excitation of ablated sample atoms is proposed. In this arrangement, a conventional Grimm-type discharge lamp is employed, but the polarity of the power supply is reversed so that the cylindrical hollow tube acts as a cathode and the glow discharge plasma is produced within this tube. A laser is irradiated to introduce sample atoms into the discharge plasma. Ablated atoms are excited by collisions with electrons and gas species, and emit characteristic radiation upon de-excitation. The experiments were conducted only in an atmosphere of helium gas so as to avoid a rapid erosion of the cathode hollow tube. Phase-sensitive detection with a lock-in amplifier was utilized to reject the continuous background emission of the plasma gas and emissions of sputtered atoms from the tube material. The unique feature of this technique is that the sampling and excitation processes can be controlled independently. The proposed technique was employed for the determination of Cr, Mn, and Ni in low-alloyed steel samples. The obtained concentrations are in good agreement with the reported values. The relative standard deviation (RSD), a measure of the analytical precision, was estimated to be 2-9% for Cr, 3-4% for Mn, and 4-11% for Ni determination.

Low-Cost, Disposable, Flexible and Highly Reproducible Screen Printed SERS Substrates for the Detection of Various Chemicals

PubMed Central

Wu, Wei; Liu, Li; Dai, Zhigao; Liu, Juhua; Yang, Shuanglei; Zhou, Li; Xiao, Xiangheng; Jiang, Changzhong; Roy, Vellaisamy A.L.

2015-01-01

Ideal SERS substrates for sensing applications should exhibit strong signal enhancement, generate a reproducible and uniform response, and should be able to fabricate in large-scale and low-cost. Herein, we demonstrate low-cost, highly sensitive, disposable and reproducible SERS substrates by means of screen printing Ag nanoparticles (NPs) on a plastic PET (Polyethylene terephthalate) substrates. While there are many complex methods for the fabrication of SERS substrates, screen printing is suitable for large-area fabrication and overcomes the uneven radial distribution. Using as-printed Ag substrates as the SERS platform, detection of various commonly known chemicals have been done. The SERS detection limit of Rhodamine 6G (R6G) is higher than the concentration of 1 × 10−10 M. The relative standard deviation (RSD) value for 784 points on the detection of R6G and Malachite green (MG) is less than 20% revealing a homogeneous SERS distribution and high reproducibility. Moreover, melamine (MA) is detected in fresh liquid-milk without additional pretreatment, which may accelerate the application of rapid on-line detection of MA in liquid milk. Our screen printing method highlights the use of large-scale printing strategies for the fabrication of well-defined functional nanostructures with applications well beyond the field of SERS sensing. PMID:25974125

Highly Sensitive and Wide-Dynamic-Range Multichannel Optical-Fiber pH Sensor Based on PWM Technique.

PubMed

Khan, Md Rajibur Rahaman; Kang, Shin-Won

2016-11-09

In this study, we propose a highly sensitive multichannel pH sensor that is based on an optical-fiber pulse width modulation (PWM) technique. According to the optical-fiber PWM method, the received sensing signal's pulse width changes when the optical-fiber pH sensing-element of the array comes into contact with pH buffer solutions. The proposed optical-fiber PWM pH-sensing system offers a linear sensing response over a wide range of pH values from 2 to 12, with a high pH-sensing ability. The sensitivity of the proposed pH sensor is 0.46 µs/pH, and the correlation coefficient R² is approximately 0.997. Additional advantages of the proposed optical-fiber PWM pH sensor include a short/fast response-time of about 8 s, good reproducibility properties with a relative standard deviation (RSD) of about 0.019, easy fabrication, low cost, small size, reusability of the optical-fiber sensing-element, and the capability of remote sensing. Finally, the performance of the proposed PWM pH sensor was compared with that of potentiometric, optical-fiber modal interferometer, and optical-fiber Fabry-Perot interferometer pH sensors with respect to dynamic range width, linearity as well as response and recovery times. We observed that the proposed sensing systems have better sensing abilities than the above-mentioned pH sensors.

Highly Sensitive and Wide-Dynamic-Range Multichannel Optical-Fiber pH Sensor Based on PWM Technique

PubMed Central

Khan, Md. Rajibur Rahaman; Kang, Shin-Won

2016-01-01

In this study, we propose a highly sensitive multichannel pH sensor that is based on an optical-fiber pulse width modulation (PWM) technique. According to the optical-fiber PWM method, the received sensing signal’s pulse width changes when the optical-fiber pH sensing-element of the array comes into contact with pH buffer solutions. The proposed optical-fiber PWM pH-sensing system offers a linear sensing response over a wide range of pH values from 2 to 12, with a high pH-sensing ability. The sensitivity of the proposed pH sensor is 0.46 µs/pH, and the correlation coefficient R2 is approximately 0.997. Additional advantages of the proposed optical-fiber PWM pH sensor include a short/fast response-time of about 8 s, good reproducibility properties with a relative standard deviation (RSD) of about 0.019, easy fabrication, low cost, small size, reusability of the optical-fiber sensing-element, and the capability of remote sensing. Finally, the performance of the proposed PWM pH sensor was compared with that of potentiometric, optical-fiber modal interferometer, and optical-fiber Fabry–Perot interferometer pH sensors with respect to dynamic range width, linearity as well as response and recovery times. We observed that the proposed sensing systems have better sensing abilities than the above-mentioned pH sensors. PMID:27834865

Determination and identification of malathion, ethion and dichlorovos using ion mobility spectrometry.

PubMed

Jafari, Mohammad T

2006-07-15

Positive ion mobility spectra of different organophosphorus pesticides such as malathion (s-(1,2-dicarb-ethoxyethyl) o,o-dimethyl dithiophosphate), ethion (o,o,o',o'-tetraethyl s,s'-methylene bis(phosphorodithioate)) and dichlorovos (2,2-dichlorovinyl dimethyl phosphate) have been studied in air at ambient pressure using ion mobility spectrometry method with (63)Ni ionization source. The limits of quantification (LOQs) were 1.0 x 10(-9), 1.0 x 10(-9) and 5.0 x 10(-9)g for malathion, ethion and dichlorovos, respectively. The working range of these compounds was about three orders of magnitude and the relative standard deviation (R.S.D.) of repeatability at the 5 microg ml(-1) level were all below 15%. Furthermore, in this study, the influences of IMS cell temperature on the ion mobility spectra of these compounds were investigated.

Quantitative sensory studies in complex regional pain syndrome type 1/RSD.

PubMed

Tahmoush, A J; Schwartzman, R J; Hopp, J L; Grothusen, J R

2000-12-01

Patients with complex regional pain syndrome type I (CRPSD1) may have thermal allodynia after application of a non-noxious thermal stimulus to the affected limb. We measured the warm, cold, heat-evoked pain threshold and the cold-evoked pain threshold in the affected area of 16 control patients and patients with complex regional pain syndrome type 1/RSD to test the hypothesis that allodynia results from an abnormality in sensory physiology. A contact thermode was used to apply a constant 1 degrees C/second increasing (warm and heat-evoked pain) or decreasing (cold and cold-evoked pain) thermal stimulus until the patient pressed the response button to show that a temperature change was felt by the patient. Student t test was used to compare thresholds in patients and control patients. The cold-evoked pain threshold in patients with CRPSD1/RSD (p <0.001) was significantly decreased when compared with the thresholds in control patients (i.e., a smaller decrease in temperature was necessary to elicit cold-pain in patients with CRPSD1/RSD than in control patients). The heat-evoked pain threshold in patients with CRPS1/RSD was (p <0.05) decreased significantly when compared with thresholds in control patients. The warm- and cold-detection thresholds in patients with CRPS1/RSD were similar to the thresholds in control patients. This study suggests that thermal allodynia in patients with CRPS1/RSD results from decreased cold-evoked and heat-evoked pain thresholds. The thermal pain thresholds are reset (decreased) so that non-noxious thermal stimuli are perceived to be pain (allodynia).

Proof of concept study: renal sympathetic denervation for treatment of polymorphic premature ventricular complexes.

PubMed

Kiuchi, Márcio Galindo; E Silva, Gustavo Ramalho; Paz, Luis Marcelo Rodrigues; Chen, Shaojie; Souto, Gladyston Luiz Lima

2016-11-01

Polymorphic premature ventricular complexes (PVCs) are very common, appearing most frequently in patients with hypertension, obesity, sleep apnea, and structural heart disease. Sympathetic hyperactivity plays a critical role in the development, maintenance, and aggravation of ventricular arrhythmias. Recently, the relevance of sympathetic activation in patients with ventricular arrhythmias was reported, and this finding suggested a potential role for catheter-based renal sympathetic denervation in reducing the arrhythmic burden. We evaluated the effectiveness of the renal sympathetic denervation (RSD) in comparison to antiarrhythmic pharmacologic therapy in reducing polymorphic PVCs refractory to medication therapy and cardiac parameters assessed by 24-h Holter monitoring and cardiac magnetic resonance (CRM), respectively, in patients with structurally normal heart. Thirty-four patients were included in this study, 14 served as control, and 20 were treated with an ablation cardiac catheter with open irrigated tip. RSD was performed by a single operator following the standard technique. All the patients included had polymorphic PVCs and structurally normal heart. Data were obtained at baseline at the 12th month of follow-up (sixth month after RSD or adjustment of antiarrhythmic dosage). In RSD group, we observed a significant decrease in the number of polymorphic PVCs from baseline 36,091 ± 3327 to 3, 6, 7 (first month after RSD, without drugs), and 12 months (sixth month after RSD, without drugs) of follow-up, 31,009 ± 3251, 20,411 ± 3820, 7701 ± 1549, and 1274 ± 749, respectively, in all patients, P < 0.0001 to all the comparisons between the mean of each time point with the mean of every other time point. No changes in mean 24-h ABPM and renal function in both groups were observed at 12th month of follow-up. However, 24-h Holter mean heart rate decreased in control group at 12th month of follow-up, which did not happen with the RSD group. At the sixth month post-RSD in comparison to baseline, a significant reduction in the number of polymorphic PVCs (∆ = -34,817 ± 3590, P < 0.0001) was observed, as well as, in CRM parameters such as left ventricular mass/body surface area (∆ = -5.4 ± 2.1 g/m 2 , P < 0.0001) and left ventricular ejection fraction (∆ = +3.0 ± 1.8 %, P < 0.0001). In comparison to control group at the same time point, these findings were statistically superior in RSD group (P > 0.05). A significant correlation was found between the Δ number of polymorphic PVCs at the sixth month (r = -0.6723, P = 0.0012) after the RSD and the total number of RSD ablated spots. Polymorphic PVCs refractory to medication therapy may be modifiable by RSD in patients without structural heart disease. Although encouraging, our data are preliminary and need to be validated in a large population and in long term.

Renal sympathetic denervation guided by renal nerve stimulation to treat ventricular arrhythmia in CKD patients with ICD

PubMed Central

Kiuchi, Márcio Galindo; Chen, Shaojie; Rodrigues Paz, Luis Marcelo; Pürerfellner, Helmut

2017-01-01

Chronic kidney disease (CKD) patients on stage 4 present greater risk rates for malignant ventricular arrhythmia events. This study examined patients with CKD in stages 1, 2, 3 and 4, left ventricular dysfunction and automatic implantable cardioverter-defibrillator (ICD). Our goal was to record the appropriate therapies, “Anti-tachycardia Therapy Pacing” (ATP) and shock events during the 18 months of follow-up and compare the incidence and severity of these at different stages of CKD, mainly in patients with CKD stage 4 underwent renal sympathetic denervation (RSD) guided by renal nerve stimulation (RNS). One hundred and fifteen patients were evaluated once every three months till 18 months of follow-up. The arrhythmic events were assessed at each follow-up visit. Comparing the groups, we can see the number of ATP and shock events recorded by ICD during 18 months of follow-up, and differences in the number of therapeutic events between the various stages of CKD. The hazard ratio (HR), 95% confidence interval (CI) and P value for ATP and shock events between all the CKD stages were evaluated by the log-rank/Mantel-Haenszel test. At the 18th month of follow-up, 75% of patients with CKD stage 4 received ATP, and 70% were treated with shock while only 20% of the subjects with CKD stage 4 that were submitted to RSD received ATP and 20% were treated with shock, P<0.0001 and P=0.0002, respectively. In our study, a decline occurred in the incidence of arrhythmias, and therefore, appropriate ICD therapies in advanced stages of CKD, reducing the risk rates for these events in patients with CKD on stage 4 after RSD guided by RNS in comparison to the other CKD stages. Our results suggest that RSD can control the higher incidence of malignant arrhythmias in advanced CKD stages. PMID:28415795

40 CFR Appendix A to Subpart A of... - Switcher Locomotives

Code of Federal Regulations, 2010 CFR

2010-07-01

... 6-539. S11 6-539. S12 6-539T. S13 6-251C. RSD-1 6-539. RSC-13 6-539. RSC-24 12-244 RS1 6-539T. RS2 1 12-244. RS3 1 12-244. RS10 1 12-244. RSC-2 1 12-244. RS3 1 12-244. RSD-4 1 12-244. RSD-5 1 12-244. T6...

40 CFR Appendix A to Subpart A of... - Switcher Locomotives

Code of Federal Regulations, 2011 CFR

2011-07-01

... 6-539. S11 6-539. S12 6-539T. S13 6-251C. RSD-1 6-539. RSC-13 6-539. RSC-24 12-244 RS1 6-539T. RS2 1 12-244. RS3 1 12-244. RS10 1 12-244. RSC-2 1 12-244. RS3 1 12-244. RSD-4 1 12-244. RSD-5 1 12-244. T6...

40 CFR Appendix A to Subpart A of... - Switcher Locomotives

Code of Federal Regulations, 2013 CFR

2013-07-01

... 6-539. S11 6-539. S12 6-539T. S13 6-251C. RSD-1 6-539. RSC-13 6-539. RSC-24 12-244 RS1 6-539T. RS2 1 12-244. RS3 1 12-244. RS10 1 12-244. RSC-2 1 12-244. RS3 1 12-244. RSD-4 1 12-244. RSD-5 1 12-244. T6...

40 CFR Appendix A to Subpart A of... - Switcher Locomotives

Code of Federal Regulations, 2012 CFR

2012-07-01

... 6-539. S11 6-539. S12 6-539T. S13 6-251C. RSD-1 6-539. RSC-13 6-539. RSC-24 12-244 RS1 6-539T. RS2 1 12-244. RS3 1 12-244. RS10 1 12-244. RSC-2 1 12-244. RS3 1 12-244. RSD-4 1 12-244. RSD-5 1 12-244. T6...

40 CFR Appendix A to Subpart A of... - Switcher Locomotives

Code of Federal Regulations, 2014 CFR

2014-07-01

... 6-539. S11 6-539. S12 6-539T. S13 6-251C. RSD-1 6-539. RSC-13 6-539. RSC-24 12-244 RS1 6-539T. RS2 1 12-244. RS3 1 12-244. RS10 1 12-244. RSC-2 1 12-244. RS3 1 12-244. RSD-4 1 12-244. RSD-5 1 12-244. T6...

Quantification of the multi-streaming effect in redshift space distortion

NASA Astrophysics Data System (ADS)

Zheng, Yi; Zhang, Pengjie; Oh, Minji

2017-05-01

Both multi-streaming (random motion) and bulk motion cause the Finger-of-God (FoG) effect in redshift space distortion (RSD). We apply a direct measurement of the multi-streaming effect in RSD from simulations, proving that it induces an additional, non-negligible FoG damping to the redshift space density power spectrum. We show that, including the multi-streaming effect, the RSD modelling is significantly improved. We also provide a theoretical explanation based on halo model for the measured effect, including a fitting formula with one to two free parameters. The improved understanding of FoG helps break the fσ8-σv degeneracy in RSD cosmology, and has the potential of significantly improving cosmological constraints.

Retrograde Suction Decompression with an Inahara Carotid Shunt for Clipping a Large Distal Internal Carotid Artery Aneurysm.

PubMed

Park, Yong Sook; Nam, Taek Kyun

2017-03-01

We describe a technique to clip a large internal carotid artery (ICA) aneurysm via a retrograde suction decompression (RSD). A large aneurysm in the right distal ICA involving the bifurcation region measuring 1.2×1.1×0.7 cm with posterior projection was managed with assisted RSD technique. The anterior choroidal artery emerged from the side wall of the aneurysm. An Inahara shunt was inserted into the ICA with neck dissection, and RSD was applied after completely clipping the aneurysm. RSD with an Inahara carotid shunt is useful for complete visualization of the aneurysm, including its surrounding structures, and for proximal control of the parent vessels, subsequently achieving satisfactory clip placement.

A statistical approach to quantification of genetically modified organisms (GMO) using frequency distributions.

PubMed

Gerdes, Lars; Busch, Ulrich; Pecoraro, Sven

2014-12-14

According to Regulation (EU) No 619/2011, trace amounts of non-authorised genetically modified organisms (GMO) in feed are tolerated within the EU if certain prerequisites are met. Tolerable traces must not exceed the so-called 'minimum required performance limit' (MRPL), which was defined according to the mentioned regulation to correspond to 0.1% mass fraction per ingredient. Therefore, not yet authorised GMO (and some GMO whose approvals have expired) have to be quantified at very low level following the qualitative detection in genomic DNA extracted from feed samples. As the results of quantitative analysis can imply severe legal and financial consequences for producers or distributors of feed, the quantification results need to be utterly reliable. We developed a statistical approach to investigate the experimental measurement variability within one 96-well PCR plate. This approach visualises the frequency distribution as zygosity-corrected relative content of genetically modified material resulting from different combinations of transgene and reference gene Cq values. One application of it is the simulation of the consequences of varying parameters on measurement results. Parameters could be for example replicate numbers or baseline and threshold settings, measurement results could be for example median (class) and relative standard deviation (RSD). All calculations can be done using the built-in functions of Excel without any need for programming. The developed Excel spreadsheets are available (see section 'Availability of supporting data' for details). In most cases, the combination of four PCR replicates for each of the two DNA isolations already resulted in a relative standard deviation of 15% or less. The aims of the study are scientifically based suggestions for minimisation of uncertainty of measurement especially in -but not limited to- the field of GMO quantification at low concentration levels. Four PCR replicates for each of the two DNA isolations seem to be a reasonable minimum number to narrow down the possible spread of results.

Effects of repeated social defeat on adolescent mice on cocaine-induced CPP and self-administration in adulthood: integrity of the blood-brain barrier.

PubMed

Rodríguez-Arias, Marta; Montagud-Romero, Sandra; Rubio-Araiz, Ana; Aguilar, María A; Martín-García, Elena; Cabrera, Roberto; Maldonado, Rafael; Porcu, Francesca; Colado, María Isabel; Miñarro, José

2017-01-01

Social stress in adulthood enhances cocaine self-administration, an effect that has been related with an increase in extracellular signal-regulated kinase and p38α mitogen-activated protein kinase phosphorylation. A detrimental effect of cocaine on blood-brain barrier (BBB) integrity has also been reported. This study evaluates the effects of repeated social defeat (RSD) during adolescence on the reinforcing and motivational effects of cocaine in adult mice and the changes induced by RSD on BBB permeability. Cocaine self-administration, conditioned place preference and quantitative analysis of claudin-5, laminin, collagen-IV and IgG immunoreactivity took place 3 weeks after RSD. Mice socially defeated during adolescence developed conditioned place preference and exhibited reinstated preference with a non-effective dose of cocaine (1 mg/kg). RSD mice needed significantly more sessions than control animals for the preference induced by 25 mg/kg of cocaine to be extinguished. However, acquisition of cocaine self-administration (0.5 mg/kg per injection) was delayed in the RSD group. Mice exposed to RSD displayed significant changes in BBB structure in adulthood, with a marked reduction in expression of the tight junction protein claudin-5 and an increase in basal laminin degradation (reflected by a decrease in laminin and collagen-IV expression) in the nucleus accumbens and hippocampus. The detrimental effect induced by cocaine (25 mg/kg) on collagen-IV expression in the hippocampus was more pronounced in RSD mice. In summary, our findings suggest that stress and cocaine can increase the long-term vulnerability of the brain to subsequent environmental insults as a consequence of a sustained disruption of the BBB. © 2015 Society for the Study of Addiction.

Differential mechanisms of binding of anti-sigma factors Escherichia coli Rsd and bacteriophage T4 AsiA to E. coli RNA polymerase lead to diverse physiological consequences.

PubMed

Sharma, Umender K; Chatterji, Dipankar

2008-05-01

Anti-sigma factors Escherichia coli Rsd and bacteriophage T4 AsiA bind to the essential housekeeping sigma factor, sigma(70), of E. coli. Though both factors are known to interact with the C-terminal region of sigma(70), the physiological consequences of these interactions are very different. This study was undertaken for the purpose of deciphering the mechanisms by which E. coli Rsd and bacteriophage T4 AsiA inhibit or modulate the activity of E. coli RNA polymerase, which leads to the inhibition of E. coli cell growth to different amounts. It was found that AsiA is the more potent inhibitor of in vivo transcription and thus causes higher inhibition of E. coli cell growth. Measurements of affinity constants by surface plasmon resonance experiments showed that Rsd and AsiA bind to sigma(70) with similar affinity. Data obtained from in vivo and in vitro binding experiments clearly demonstrated that the major difference between AsiA and Rsd is the ability of AsiA to form a stable ternary complex with RNA polymerase. The binding patterns of AsiA and Rsd with sigma(70) studied by using the yeast two-hybrid system revealed that region 4 of sigma(70) is involved in binding to both of these anti-sigma factors; however, Rsd interacts with other regions of sigma(70) as well. Taken together, these results suggest that the higher inhibition of E. coli growth by AsiA expression is probably due to the ability of the AsiA protein to trap the holoenzyme RNA polymerase rather than its higher binding affinity to sigma(70).

Pulmonary vein isolation combined with spironolactone or renal sympathetic denervation in patients with chronic kidney disease, uncontrolled hypertension, paroxysmal atrial fibrillation, and a pacemaker.

PubMed

Kiuchi, Márcio Galindo; Chen, Shaojie; Hoye, Neil Alexander; Pürerfellner, Helmut

2018-01-01

Atrial fibrillation (AF) commonly occurs in chronic kidney disease (CKD), occasioning adverse outcomes. Merging pulmonary vein isolation (PVI) and renal sympathetic denervation (RSD) may decrease the recurrence of AF in subjects with CKD and uncontrolled hypertension. We considered that RSD could reduce the recurrence of AF in patients with CKD by modulating sympathetic hyperactivity. We aimed to evaluate the impact of RSD or spironolactone 50 mg/day associated with PVI in reducing systolic blood pressure (BP), AF recurrence, and AF burden in patients with a history of paroxysmal AF and mild CKD. This was a single-center, prospective, longitudinal, randomized, double-blind study. The individuals were randomly divided into two groups (PVI + spironolactone, n = 36, and PVI + RSD, n = 33). All of them were followed for exactly 1 year to assess maintenance of sinus rhythm and to monitor the other variables. Ambulatory BP measurements were reduced in both groups and at the 12th month also differed between groups. Significantly more patients in the PVI + RSD (61%) than in the PVI + spironolactone group (36%) were AF-free at the 12th month of follow-up, P = 0.0242. Toward the end of the study, the mean AF burden was lower in the PVI + RSD group as compared to PVI + spironolactone group, at the 9th month: ∆ = - 10% (P < 0.0001), and at the 12th month: ∆ = - 12% (P < 0.0001), respectively. PVI + RSD is safe and appears to be superior to PVI + spironolactone in BP reduction, augmentation of AF event-free rate, reduction of AF burden, and improvement of renal function.

Differential Mechanisms of Binding of Anti-Sigma Factors Escherichia coli Rsd and Bacteriophage T4 AsiA to E. coli RNA Polymerase Lead to Diverse Physiological Consequences▿

PubMed Central

Sharma, Umender K.; Chatterji, Dipankar

2008-01-01

Anti-sigma factors Escherichia coli Rsd and bacteriophage T4 AsiA bind to the essential housekeeping sigma factor, σ70, of E. coli. Though both factors are known to interact with the C-terminal region of σ70, the physiological consequences of these interactions are very different. This study was undertaken for the purpose of deciphering the mechanisms by which E. coli Rsd and bacteriophage T4 AsiA inhibit or modulate the activity of E. coli RNA polymerase, which leads to the inhibition of E. coli cell growth to different amounts. It was found that AsiA is the more potent inhibitor of in vivo transcription and thus causes higher inhibition of E. coli cell growth. Measurements of affinity constants by surface plasmon resonance experiments showed that Rsd and AsiA bind to σ70 with similar affinity. Data obtained from in vivo and in vitro binding experiments clearly demonstrated that the major difference between AsiA and Rsd is the ability of AsiA to form a stable ternary complex with RNA polymerase. The binding patterns of AsiA and Rsd with σ70 studied by using the yeast two-hybrid system revealed that region 4 of σ70 is involved in binding to both of these anti-sigma factors; however, Rsd interacts with other regions of σ70 as well. Taken together, these results suggest that the higher inhibition of E. coli growth by AsiA expression is probably due to the ability of the AsiA protein to trap the holoenzyme RNA polymerase rather than its higher binding affinity to σ70. PMID:18359804

Distinct impacts of reductive soil disinfestation and chemical soil disinfestation on soil fungal communities and memberships.

PubMed

Zhao, Jun; Zhou, Xing; Jiang, Anqi; Fan, Juanzi; Lan, Tao; Zhang, Jinbo; Cai, Zucong

2018-06-21

Soil disinfestation is an important agricultural practice to conquer soil-borne diseases and thereby ensure crop productivity. Reductive soil disinfestation (RSD) had been developed as an environmentally friendly alternative to chemical soil disinfestation (CSD). However, the differences between CSD and RSD on soil-borne pathogen suppression and fungal community structure remain poorly understood. In this work, five treatments, i.e., untreated soil (CK), CSD with 0.5 t ha -1 dazomet (DZ), RSD with 10 t ha -1 ethanol (ET), 15 t ha -1 sugarcane bagasse (SB), and 15 t ha -1 bean dregs (BD), were performed to investigate their influences on disinfestation efficiency, fungal abundance, diversity, and community structure via quantitative PCR and high-throughput sequencing. RSD-related treatments, especially the BD treatment, effectively alleviated soil acidification and salinization. The fungal abundance and microbial activity considerably increased in the BD treatment and significantly declined in the DZ treatment as compared to the CK treatment. Moreover, both CSD and RSD-related treatments significantly inhibited the population of Fusarium oxysporum and the relative abundance of genus Fusarium. Fungal community structure was notably altered by CSD and RSD practices. Furthermore, both CSD and RSD harbored a distinct unique microbiome, with the DZ treatment dominated by the genus Mortierella and BD treatment predominated by the genera Zopfiella, Chaetomium, and Penicillium. Taken together, these results indicate that the BD treatment could considerably alleviate the soil deterioration, improve soil microbial activity, and reassemble a non-pathogen unique microbiome that have more disease-suppressive agents and thus might be a promising disinfestation practice to control soil-borne disease in monoculture system.

Synthesis of magnetic molecularly imprinted polymers for the selective separation and determination of metronidazole in cosmetic samples.

PubMed

Liu, Min; Li, Xiao-Yan; Li, Jun-Jie; Su, Xiao-Meng; Wu, Zong-Yuan; Li, Peng-Fei; Lei, Fu-Hou; Tan, Xue-Cai; Shi, Zhan-Wang

2015-05-01

In this study, novel magnetic molecularly imprinted polymers (MMIPs) were developed as a sorbent for solid-phase extraction (SPE) and used for the selective separation of metronidazole (MNZ) in cosmetics; MNZ was detected by high-performance liquid chromatography (HPLC). First, magnetic Fe3O4 nanoparticles (NPs) were prepared by the co-precipitation of Fe(2+)and Fe(3+) ions in an ammonia solution; then oleic acid (OA) was modified onto the surface of Fe3O4NPs. Finally, the MMIP was prepared by aqueous suspension polymerization, involving the copolymerization of Fe3O4NPs@OA with MNZ as the template molecule, methacrylic acid (MAA) as the functional monomer, ethylene glycol maleic rosinate acrylate (EGMRA) as the cross-linking agent, and 2,2-azobisisobutyronitrile (AIBN) as the initiator. The MMIP materials showed high selective adsorption capacity and fast binding kinetics for MNZ; the maximum adsorption amount of the MMIP to MNZ was 46.7 mg/g. The assay showed a linear range from 0.1 to 20.0 μg/mL for MNZ with the correlation coefficient 0.999. The relative standard deviations (RSD) of intra- and inter-day ranging from 0.71 to 2.45% and from 1.06 to 5.20% were obtained. The MMIP can be applied to the enrichment and determination of MNZ in cosmetic products with the recoveries of spiked toner, powder, and cream cosmetic samples ranging from 90.6 to 104.2, 84.1 to 91.4, and 90.3 to 100.4%, respectively, and the RSD was <3.54%.

Magnetic mesoporous molecularly imprinted polymers based on surface precipitation polymerization for selective enrichment of triclosan and triclocarban.

PubMed

Wang, Xuemei; Huang, Pengfei; Ma, Xiaomin; Du, Xinzhen; Lu, Xiaoquan

2018-02-16

Novel magnetic mesoporous molecularly imprinted polymers (MMIPs) were prepared based on surface precipitation polymerization using Triclosan (TCS) as template and methacrylic acid as functional monomer. The synthesized MMIPs-TCS were applied to the adsorbent of magnetic solid-phase extraction (MSPE) coupled with HPLC for the enrichment and determination of TCS. The MMIPs-TCS were characterized by fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N 2 adsorption-desorption transmission, and vibrating sample magnetometry. Under the optimum condition, the MMIPs-TCS-MSPE-HPLC method shows low limits of detection (LODs) (0.20-0.90 μg L -1 ) and limits of quantification detection (LOQs) (0.66-2.97 μg L -1 ), wide linear ranges from 10.0 to 1000 μg L -1 for each compound with exception of 2,4,6-TCP from 20.0 to 1000 μg L -1 , and acceptable reproducibility (relative standard deviation, RSD <6.6% for intra-day, RSD <8.1% for inter-day). The satisfactory recoveries were in the range of 89.5%-108.4% with good RSDs less than 8.0% at the three spiked levels of 20, 50 and 80 μg L -1 . Moreover, the adsorption experiments show the MMIPs-TCS possess rapid binding affinity, excellent magnetic response, specific selectivity and high adsorption capacity toward TCS with a maximum adsorption capacity of 1955.8 μg g -1 . Copyright © 2018 Elsevier B.V. All rights reserved.

Simultaneous stereoselective analysis by capillary electrophoresis of tramadol enantiomers and their main phase I metabolites in urine.

PubMed

Rudaz, S; Veuthey, J L; Desiderio, C; Fanali, S

1999-06-18

Capillary zone electrophoresis was successfully applied to the enantiomeric resolution of racemic tramadol and its six phase I metabolites using carboxymethylated beta-cyclodextrin (CMB) added to the background electrolyte (BGE). Baseline resolution of tramadol and its metabolites was obtained in less than 30 min using a 50 mM phosphate buffer (pH 2.5) containing 5 mM of CMB. Chiral determinations of tramadol and its main three metabolites, O-demethyltramadol (M1), N-demethyltramadol (M2) and O-demethyl-N-demethyltramadol (M5), were performed in urine after a simple double liquid-liquid extraction of 200 microliters of biological material. In the tested concentration range (0.5-20 micrograms/ml, except for M2: 0.5-10 micrograms/ml) coefficients of correlation superior than 0.994 were obtained. Within-day variation determined on three different concentrations for each enantiomers showed accuracies ranging from 95.4% to 103.2%. The relative standard deviation (RSD) of these assays was determined to be less than 10.0%. Day-to-day variation presented accuracies ranging from 96.3% to 106.5% with a RSD less than 9.0%. After oral administration of 100 mg of tramadol hydrochloride to an healthy volunteer, the urinary excretion was monitored during 30 h. About 15% of the dose was excreted as unchanged tramadol. The enantiomeric ratios of all the excreted analytes, T, M1, M2 and M5, were found to be very different to 1.0, showing that a stereoselective metabolism of tramadol clearly occurred.

Development and validation of rapid and simultaneous method for determination of 12 hair-growth compounds in adulterated products by UHPLC-MS/MS.

PubMed

Park, Han Na; Lee, Ji Hyun; Park, Sung-Kwan; Baek, Sun Young; Lee, Yong-Moon; Kang, Hoil

2018-03-01

Synthetic hair-growth compounds have been illegally used in diverse products to enhance the short-term efficacy of these products. In this study, a rapid and simultaneous method for the determination of hair-growth compounds in adulterated products based on ultra high pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed and validated. The limit of detection (LOD) and limit of quantitation (LOQs) of the method were 0.08-43.6ng/mL and 0.27-145ng/mL for the solid-, liquid-, and cream-type samples, respectively. Good calibration linearity for all compounds was demonstrated with a correlation coefficient (r 2 ) higher than 0.997. The intra- and inter-assay precisions were within 11%. The corresponding accuracies were 86-117% and 81-113%, respectively. The mean recoveries obtained for the solid-, liquid, and cream-type samples ranged from 87 to 114%, with a relative standard deviation (RSD) within 6%. The RSD of the stability evaluated at 4°C for 48h was less than 6%. The established method was used to screen 76 samples advertised as hair-growth treatments, from online and offline markets, over the course of two years. In 10% of the samples, four compounds, including triaminodil, minoxidil, finasteride, methyltestosterone, and testosterone-propionate were detected. The concentrations were in the range of 0.5-16.4mg/g. This technique provides a reliable platform for technical analysis for continuous monitoring of adulterated products to protect public health. Copyright © 2018 Elsevier B.V. All rights reserved.

Procedures for determination of detection limits: application to high-performance liquid chromatography analysis of fat-soluble vitamins in human serum.

PubMed

Browne, Richard W; Whitcomb, Brian W

2010-07-01

Problems in the analysis of laboratory data commonly arise in epidemiologic studies in which biomarkers subject to lower detection thresholds are used. Various thresholds exist including limit of detection (LOD), limit of quantification (LOQ), and limit of blank (LOB). Choosing appropriate strategies for dealing with data affected by such limits relies on proper understanding of the nature of the detection limit and its determination. In this paper, we demonstrate experimental and statistical procedures generally used for estimating different detection limits according to standard procedures in the context of analysis of fat-soluble vitamins and micronutrients in human serum. Fat-soluble vitamins and micronutrients were analyzed by high-performance liquid chromatography with diode array detection. A simulated serum matrix blank was repeatedly analyzed for determination of LOB parametrically by using the observed blank distribution as well as nonparametrically by using ranks. The LOD was determined by combining information regarding the LOB with data from repeated analysis of standard reference materials (SRMs), diluted to low levels; from LOB to 2-3 times LOB. The LOQ was determined experimentally by plotting the observed relative standard deviation (RSD) of SRM replicates compared with the concentration, where the LOQ is the concentration at an RSD of 20%. Experimental approaches and example statistical procedures are given for determination of LOB, LOD, and LOQ. These quantities are reported for each measured analyte. For many analyses, there is considerable information available below the LOQ. Epidemiologic studies must understand the nature of these detection limits and how they have been estimated for appropriate treatment of affected data.

Polypyrrole-magnetite dispersive micro-solid-phase extraction combined with ultraviolet-visible spectrophotometry for the determination of rhodamine 6G and crystal violet in textile wastewater.

PubMed

Kamaruddin, Amirah Farhan; Sanagi, Mohd Marsin; Wan Ibrahim, Wan Aini; Md Shukri, Dyia S; Abdul Keyon, Aemi S

2017-11-01

Polypyrrole-magnetite dispersive micro-solid-phase extraction method combined with ultraviolet-visible spectrophotometry was developed for the determination of selected cationic dyes in textile wastewater. Polypyrrole-magnetite was used as adsorbent due to its thermal stability, magnetic properties, and ability to adsorb Rhodamine 6G and crystal violet. Dispersive micro-solid-phase extraction parameters were optimized, including sample pH, adsorbent amount, extraction time, and desorption solvent. The optimum polypyrrole-magnetite dispersive micro-solid phase-extraction conditions were sample pH 8, 60 mg polypyrrole-magnetite adsorbent, 5 min of extraction time, and acetonitrile as the desorption solvent. Under the optimized conditions, the polypyrrole-magnetite dispersive micro-solid-phase extraction with ultraviolet-visible method showed good linearity in the range of 0.05-7 mg/L (R 2  > 0.9980). The method also showed a good limit of detection for the dyes (0.05 mg/L) and good analyte recoveries (97.4-111.3%) with relative standard deviations < 10%. The method was successfully applied to the analysis of dyes in textile wastewater samples where the concentration found was 1.03 mg (RSD ±7.9%) and 1.13 mg/L (RSD ± 4.6%) for Rhodamine 6G and crystal violet, respectively. It can be concluded that this method can be adopted for the rapid extraction and determination of dyes at trace concentration levels. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Developing analytical approaches to explore the connection between endocrine-active pharmaceuticals in water to effects in fish

USGS Publications Warehouse

Jones-Lepp, Tammy L.; Taniguchi-Fu, Randi L.; Morgan, Jade; Nance Jr., Trevor; Ward, Matthew; Alvarez, David A.; Mills, Lesley

2015-01-01

The emphasis of this research project was to develop and optimize a solid-phase extraction method and highperformance liquid chromatography-electrospray ionizationmass spectrometry method, such that a linkage between the detection of endocrine-active pharmaceuticals (EAPs) in the aquatic environment and subsequent effects on fish populations could eventually be studied. Four EAPs were studied: tamoxifen (TAM), exemestane (EXE), letrozole (LET), anastrozole (ANA); and three TAM metabolites: 4- hydroxytamoxifen, e/z endoxifen, and n-desmethyl tamoxifen. In aqueous matrices, the use of isotopically labeled standards for the EAPs allowed for the generation of good recoveries, greater than 80 %, and low relative standard deviations (% RSDs) (3 to 27 %). TAM metabolites had lower recoveries in the spiked water matrices: 35 to 93 % in waste/source water compared to 58 to 110 % in DI water. The precision in DI water was acceptable ranging from 8 to 38 % RSD. However, the precision in real environmental wastewaters could be poor, ranging from 15 to 120 % RSD, dependent upon unique matrix effects. In plasma, the overall recoveries of the EAPs were acceptable: 88 to 110 %, with %RSDs of 6 to 18 % (Table 3). The spiked recoveries of the TAM metabolites from plasma were good, ranging from 77 to 120 %, with %RSDs ranging from 27 to 32 %. Two of the TAM metabolites, 4- hydroxytamoxifen and n-desmethyl tamoxifen, were confirmed in most of the environmental aqueous samples. The discovery of TAM metabolites demonstrates that the source of the TAM metabolites, TAM, is constant, introducing a pseudo-persistence of this chemical into the environment.

Electrothermal atomic absorption spectrometric determination of arsenic in essential lavender and rose oils.

PubMed

Karadjova, Irina B; Lampugnani, Leonardo; Tsalev, Dimiter L

2005-02-28

Analytical procedures for electrothermal atomic absorption spectrometric (ETAAS) determination of arsenic in essential oils from lavender (Lavendula angustifolia) and rose (Rosa damascena) are described. For direct ETAAS analysis, oil samples are diluted with ethanol or i-propanol for lavender and rose oil, respectively. Leveling off responses of four different arsenic species (arsenite, arsenate, monomethylarsonate and dimethylarsinate) is achieved by using a composite chemical modifier: l-cysteine (0.05gl(-1)) in combination with palladium (2.5mug) and citric acid (100mug). Transverse-heated graphite atomizer (THGA) with longitudinal Zeeman-effect background correction and 'end-capped' graphite tubes with integrated pyrolytic graphite platforms, pre-treated with Zr-Ir for permanent modification are employed as most appropriate atomizer. Calibration with solvent-matched standard solutions of As(III) is used for four- and five-fold diluted samples of lavender and rose oil, respectively. Lower dilution factors required standard addition calibration by using aqueous (for lavender oil) or i-propanol (for rose oil) solutions of As(III). The limits of detection (LOD) for the whole analytical procedure are 4.4 and 4.7ngg(-1) As in levender and rose oil, respectively. The relative standard deviation (R.S.D.) for As at 6-30ngg(-1) levels is between 8 and 17% for both oils. As an alternative, procedure based on low temperature plasma ashing in oxygen with ETAAS, providing LODs of 2.5 and 2.7ngg(-1) As in levender and rose oil, respectively, and R.S.D. within 8-12% for both oils has been elaborated. Results obtained by both procedures are in good agreement.

Spectrophotometric determination of flucloxacillin and dicloxacillin in pure and dosage forms.

PubMed

El-Dien, F A Nour; Mohamed, Gehad G; Farag, Eman Y Z A

2006-05-01

A simple, rapid and accurate spectrophotometric method for the determination of antibiotic drugs, flucloxacillin (Fluclox) and dicloxacillin (Diclox), in pure form and different pharmaceutical preparations has been developed. The charge transfer (CT) reactions between Fluclox and Diclox as electron donors and 7,7,8,8-tetracyanoquinodimethane (TCNQ) and tetracyanoethylene (TCNE) as pi-acceptors to give highly coloured complex species have been spectrophotometrically studied. The optimum experimental conditions for these CT reactions have been studied carefully. Beer's law is obeyed over the concentration ranges of 4-180 microg mL(-1) and 4-70 microg mL(-1) for Fluclox and Diclox drugs using TCNQ and TCNE reagents, respectively. The Sandell sensitivities (S) are found to be 0.016-0.035 microg cm(-2) and 0.011-0.016 microg cm(-2) for Fluclox and Diclox, respectively, which indicate the high sensitivity of the proposed method. The relative standard deviations (R.S.D.: 0.08-0.49 and 0.15-0.80) for the determination of Fluclox and (R.S.D.: 0.05-0.75 and 0.13-0.75) for Diclox were obtained for four to six replicates using TCNQ and TCNE reagents, respectively, refer to the high accuracy and precision of the proposed method. These results are also confirmed by the between-day precision and the percent recovery of 99.90-100.1 and 99.60-100.4 for Fluclox and 99.90-100.5 and 99.40-100.1 for Diclox using TNCQ and TCNE reagents, respectively. The results obtained for the two reagents are comparable with those obtained by the official method.

Extemporaneous procedures for dissolving risedronate tablets for oral administration and for feeding tubes.

PubMed

Dansereau, Richard J; Crail, Debbie J

2005-01-01

Risedronate (Actonel, Procter & Gamble Pharmaceuticals) is commercially available only as film-coated tablets. Extemporaneous procedures for dissolving tablets for feeding tubes and for preparation of an oral liquid have not previously been evaluated. To evaluate procedures for dissolving risedronate sodium tablets for administration in liquid form and drug recovery following dissolution in cups and following passage through different types of feeding tubes. Tablets (5 and 35 mg) were individually dispersed in 2 oz of water. After 2 minutes, the solution was stirred for 30 seconds, dispensed, and rinsed with an additional 4 oz of water. The sample was filtered and analyzed by HPLC. Ten replicates were performed using the various cups. Gastrostomy and nasoenteric tubes were flushed with 1 oz of water. Individual tablets were dispersed in 2 oz of water; after 2 minutes, the solution was stirred for 30 seconds and poured through the tube and flushed with 1 oz of water. Samples were filtered and analyzed by HPLC. Ten replicates were performed for each type of feeding tube. For cups, the mean amount of drug recovered ranged from 95.7% to 100.5% of the label claim, with a relative standard deviation (RSD) range of 1.1-6.3%. For gastrostomy and nasoenteric tubes, the mean amount of drug recovered ranged from 98.3% to 101.9% of label claim, with an RSD range of 0.9-3.3%. A simple and accurate procedure was developed for dissolving risedronate tablets in water to prepare a liquid formulation for administration orally or through feeding tubes.

Increased efficacy for in-house validation of real-time PCR GMO detection methods.

PubMed

Scholtens, I M J; Kok, E J; Hougs, L; Molenaar, B; Thissen, J T N M; van der Voet, H

2010-03-01

To improve the efficacy of the in-house validation of GMO detection methods (DNA isolation and real-time PCR, polymerase chain reaction), a study was performed to gain insight in the contribution of the different steps of the GMO detection method to the repeatability and in-house reproducibility. In the present study, 19 methods for (GM) soy, maize canola and potato were validated in-house of which 14 on the basis of an 8-day validation scheme using eight different samples and five on the basis of a more concise validation protocol. In this way, data was obtained with respect to the detection limit, accuracy and precision. Also, decision limits were calculated for declaring non-conformance (>0.9%) with 95% reliability. In order to estimate the contribution of the different steps in the GMO analysis to the total variation variance components were estimated using REML (residual maximum likelihood method). From these components, relative standard deviations for repeatability and reproducibility (RSD(r) and RSD(R)) were calculated. The results showed that not only the PCR reaction but also the factors 'DNA isolation' and 'PCR day' are important factors for the total variance and should therefore be included in the in-house validation. It is proposed to use a statistical model to estimate these factors from a large dataset of initial validations so that for similar GMO methods in the future, only the PCR step needs to be validated. The resulting data are discussed in the light of agreed European criteria for qualified GMO detection methods.

MMSE and MoCA in Parkinson’s disease and dementia with Lewy bodies: a multicenter 1-year follow-up study

PubMed Central

Weis, L.; Bostantjopoulou, S.; Stefanova, E.; Falup-Pecurariu, C.; Kramberger, M. G.; Geurtsen, G. J.; Antonini, A.; Weintraub, D.; Aarsland, D.

2016-01-01

The Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA) are the most commonly used scales to test cognitive impairment in Lewy body disease (LBD), but there is no consensus on which is best suited to assess cognition in clinical practice and most sensitive to cognitive decline. Retrospective cohort study of 265 LBD patients [Parkinson’s disease (PD) without dementia (PDnD, N = 197), PD with dementia (PDD, N = 40), and dementia with Lewy bodies (DLB, N = 28)] from an international consortium who completed both the MMSE and MoCA at baseline and 1-year follow-up (N = 153). Percentage of relative standard deviation (RSD%) at baseline was the measure of inter-individual variance, and estimation of change (Cohen’s d) over time was calculated. RSD% for the MoCA (21 %) was greater than for the MMSE (13 %) (p = 0.03) in the whole group. This difference was significant only in PDnD (11 vs. 5 %, p < 0.01), but not in PDD (30 vs. 19 %, p = 0.37) or DLB (15 vs. 14 %, p = 0.78). In contrast, the 1-year estimation of change did not differ between the two tests in any of the groups (Cohen’s effect <0.20 in each group). MMSE and MoCA are equal in measuring the rate of cognitive changes over time in LBD. However, in PDnD, the MoCA is a better measure of cognitive status as it lacks both ceiling and floor effects. PMID:26852137

Determination of the Marker Diarylheptanoid Phytoestrogens in Curcuma comosa Rhizomes and Selected Herbal Medicinal Products by HPLC-DAD.

PubMed

Yingngam, Bancha; Brantner, Adelheid; Jinarat, Damrongsak; Kaewamatawong, Rawiwun; Rungseevijitprapa, Wandee; Suksamrarn, Apichart; Piyachaturawat, Pawinee; Chokchaisiri, Ratchanaporn

2018-01-01

A method for quantification of diarylheptanoids in Curcuma comosa rhizomes and selected pharmaceutical preparations was established by using HPLC-diode array detector (DAD). The chromatographic separation of three diarylheptanoids [(3S)-1-(3,4-dihydroxy-phenyl)-7-phenyl-(6E)-6-hepten-3-ol (1), (3R)-1,7-diphenyl-(4E,6E)-4,6-heptadien-3-ol (2), and (3S)-1,7-diphenyl-(6E)-6-hepten-3-ol (3)] was performed on a Luna C 18 analytical column using gradient elution with 0.5% acetic acid in water and acetonitrile with a flow rate of 1 mL/min and a column temperature of 35°C. The calibration curves for the analytes showed good linearity (R 2 >0.999), high precision (relative standard deviation (RSD) <2%) and acceptable recovery (98.35-103.90%, RSD <2%). The limit of detection (LOD) and limit of quantification (LOQ) were 0.06-0.22 and 0.18-0.69 µg/mL, respectively. The results of all validated parameters were within the limits according to the International Conference on Harmonization (ICH) Guidelines. The established method was successfully applied for qualitative and quantitative determination of the three constituents in different samples of C. comosa and some commercial products in capsules. The simplicity, rapidity, and reliability of the method could be useful for the fingerprint analysis and standardization of diarylheptanoids, which are responsible for the estrogenic activity in raw materials and herbal medicinal products of C. comosa.

Design of an optically stable pH sensor based on immobilization of Giemsa on triacetylcellulose membrane.

PubMed

Khodadoust, Saeid; Kouri, Narges Cham; Talebiyanpoor, Mohammad Sharif; Deris, Jamile; Pebdani, Arezou Amiri

2015-12-01

In this work a simple, inexpensive, and sensitive optical sensor based on triacetylcellulose membrane as solid support was developed by using immobilization of Giemsa indicator for pH measurement. In this method, the influence variables on the membrane performance including pH concentration of indicator, response time, ionic strength, and reversibility were investigated. At optimum values of all variables the response of optical pH sensor is linear in the pH range of 3.0-12.0. This optical sensor was produced through simultaneous binding of the Giemsa on the activated triacetylcellulose membrane which responded to the pH changes in a broader linear range within less than 2.0 min and suitable reproducibility (RSD<5%). Stability results showed that this sensor was stable after 6 months of storage in the water/ethanol (50:50, v/v) solution without any measurable divergence in response properties (less than 5% RSD). Copyright © 2015 Elsevier B.V. All rights reserved.

Development of a SPME-GC-MS method for the determination of volatile compounds in Shanxi aged vinegar and its analytical characterization by aroma wheel.

PubMed

Zhu, Hong; Zhu, Jie; Wang, Lili; Li, Zaigui

2016-01-01

A solid-phase microextraction followed by gas chromatography-mass spectrometry method was developed to determine the volatile compounds in Shanxi aged vinegar. The optimal extraction conditions were: 50 °C for 20 min with a PDMS/DVB fiber. This analytical method was validated and showed satisfactory repeatability (0.5 %

Determination of volatile corrosion inhibitors by capillary electrophoresis.

PubMed

Pereira, Elisabete A; Tavares, Marina F M

2004-10-08

In this work, a capillary electrophoresis (CE) method using indirect UV detection (214nm) for the simultaneous determination of monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), diethylethanolamine (DEEA), monocyclohexylamine (MCHA) and dicyclohexylamine (DCHA) in water/ethanol extracts of wrapping materials containing volatile corrosion inhibitors (VCIs) was described. A running buffer consisting of 0.010 molL(-1) imidazole, 0.010 molL(-1) 2-hydroxyisobutyric acid (HIBA) and 0.010 molL(-1) 18-crown-6 ether enabled separation of the analytes in less than 7 min. A few method validation parameters were determined revealing good migration time repeatability (<0.7% RSD) and area repeatability (< 1.8% RSD). Limits of detection were in the range of 0.52-1.54 mg L(-1). Recovery values were in the range of 94.8-100.9%. The methodology was successfully applied to the analysis of three commercial products (VCI treated paper, foam and plastic). The concentration of amines in these materials varied from 0.050 to 22.3% (w/w).

Validated method for the analysis of goji berry, a rich source of zeaxanthin dipalmitate.

PubMed

Karioti, Anastasia; Bergonzi, Maria Camilla; Vincieri, Franco F; Bilia, Anna Rita

2014-12-31

In the present study an HPLC-DAD method was developed for the determination of the main carotenoid, zeaxanthin dipalmitate, in the fruits of Lycium barbarum. The aim was to develop and optimize an extraction protocol to allow fast, exhaustive, and repeatable extraction, suitable for labile carotenoid content. Use of liquid N2 allowed the grinding of the fruit. A step of ultrasonication with water removed efficiently the polysaccharides and enabled the exhaustive extraction of carotenoids by hexane/acetone 50:50. The assay was fast and simple and permitted the quality control of a large number of commercial samples including fruits, juices, and a jam. The HPLC method was validated according to ICH guidelines and satisfied the requirements. Finally, the overall method was validated for precision (% RSD ranging between 3.81 and 4.13) and accuracy at three concentration levels. The recovery was between 94 and 107% with RSD values <2%, within the acceptable limits, especially if the difficulty of the matrix is taken into consideration.

Quantification of the multi-streaming effect in redshift space distortion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Yi; Oh, Minji; Zhang, Pengjie, E-mail: yizheng@kasi.re.kr, E-mail: zhangpj@sjtu.edu.cn, E-mail: minjioh@kasi.re.kr

Both multi-streaming (random motion) and bulk motion cause the Finger-of-God (FoG) effect in redshift space distortion (RSD). We apply a direct measurement of the multi-streaming effect in RSD from simulations, proving that it induces an additional, non-negligible FoG damping to the redshift space density power spectrum. We show that, including the multi-streaming effect, the RSD modelling is significantly improved. We also provide a theoretical explanation based on halo model for the measured effect, including a fitting formula with one to two free parameters. The improved understanding of FoG helps break the f σ{sub 8}−σ {sub v} degeneracy in RSD cosmology,more » and has the potential of significantly improving cosmological constraints.« less

Development and validation of a generic high-performance liquid chromatography for the simultaneous separation and determination of six cough ingredients: Robustness study on core-shell particles.

PubMed

Yehia, Ali Mohamed; Essam, Hebatallah Mohamed

2016-09-01

A generally applicable high-performance liquid chromatographic method for the qualitative and quantitative determination of pharmaceutical preparations containing phenylephrine hydrochloride, paracetamol, ephedrine hydrochloride, guaifenesin, doxylamine succinate, and dextromethorphan hydrobromide is developed. Optimization of chromatographic conditions was performed for the gradient elution using different buffer pH values, flow rates and two C18 stationary phases. The method was developed using a Kinetex® C18 column as a core-shell stationary phase with a gradient profile using buffer pH 5.0 and acetonitrile at 2.0 mL/min flow rate. Detection was carried out at 220 nm and linear calibrations were obtained for all components within the studied ranges. The method was fully validated in agreement with ICH guidelines. The proposed method is specific, accurate and precise (RSD% < 3%). Limits of detection are lower than 2.0 μg/mL. Qualitative and quantitative responses were evaluated using experimental design to assist the method robustness. The method was proved to be highly robust against 10% change in buffer pH and flow rate (RSD% < 10%), however, the flow rate may significantly influence the quantitative responses of phenylephrine, paracetamol, and doxylamine (RSD% > 10%). Satisfactory results were obtained for commercial combinations analyses. Statistical comparison between the proposed chromatographic and official methods revealed no significant difference. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Trace analysis of glyphosate in water by capillary electrophoresis on a chip with high sample volume loadability.

PubMed

Horčičiak, Michal; Masár, Marián; Bodor, Róbert; Danč, Ladislav; Bel, Peter

2012-03-01

A new method for the determination of trace glyphosate (GLYP), non-selective pesticide, by CZE with online ITP pre-treatment of drinking waters on a column-coupling (CC) chip has been developed. CC chip was equipped with two injection channels of 0.9 and 9.9 μL volumes, two separation channels of 9.3 μL total volume and a pair of conductivity detectors. A very effective ITP sample clean-up performed in the first channel at low pH (3.2) was introduced for quick CZE resolution and detection of GLYP carried out at higher pH (6.1) in the second channel on the CC chip. The LOD for GLYP was estimated at 2.5 μg/L (15 nmol/L) using a 9.9 |mL volume of the injection channel. ITP-CZE analyses of model and real samples have provided very favorable intra-day (0.1-1.2% RSD) and inter-day (2.9% RSD) repeatabilities of the migration time for GLYP while 0.2-6.9% RSD values were typical for the peak area data. Recoveries of GLYP in spiked drinking water varied in the range of 99-109%. A minimum pre-treatment of drinking water (degassing and dilution) and a short analysis time (ca. 10 min) were distinctive features of ITP-CZE determinations of GLYP on the CC chip with high sample volume loaded, as well. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Rapid determination of the components in ternary blended edible oil using near infrared transmission spectroscopy].

PubMed

Liu, Fu-Li; Chen, Hua-Cai

2009-08-01

The FT-NIR transmission spectra of ternary blended edible oil samples were collected over 10 000-4 200 cm(-1). After being pretreated with different methods, the calibration models of quantitative analysis of soybean oil, peanut oil and corn oil contents in ternary blended edible oil were established using partial least square (PLS) regression. The accuracy and precision of the models for the predicted sample set were examined to make sure of the practicability of the models. After being pretreated with first derivative and multiplicative signal correction (FD+MSC), the optimal soybean oil NIR model was built over 5 450.1-4 597.7 cm(-1). The best prediction model for peanut oil was established between 7 521.3 and 6 098.1 cm(-1) after using first derivative with straight line subtraction (FD+SLS) preprocess method. The best pretreated method and the best spectrum range for corn oil content model were first derivative (FD) and 9 993.7-7 498.2 cm(-1), respectively. The best correlation coefficients (R2) of the three prediction models were 99.89%, 99.88% and 99.76%, respectively. The RMSEP of the soybean oil content model was 1.09%, while the peanut oil prediction model's RMSEP was 1.17%, and 1.48% for the corn oil prediction model. The values of the t-test were between 0.007 9 and 0.371 9, and all values of the relative standard deviation (RSD) were less than 1.50%. The results showed that NIR could be an ideal tool for fast determination of the soybean oil, peanut oil and corn oil contents in ternary blended edible oil.

Enantioseparation and determination of the chiral fungicide furametpyr enantiomers in rice, soil, and water by high-performance liquid chromatography.

PubMed

Dong, Fengshou; Chen, Xiu; Xu, Jun; Liu, Xingang; Chen, Zenglong; Li, Yuanbo; Zhang, Hongjun; Zheng, Yongquan

2013-12-01

The chiral fungicide furametpyr is widely used in the rice field to control rice sheath blight; however, furametpyr enantiomers are treated as just one compound in traditional achiral analysis, which gives only partial information. An effective chiral analytical method was developed for the resolution and determination of the fungicide furametpyr enantiomers in rice, soil, and water samples. Furametpyr enantiomers were excellently separated and determined on a Chiralpak AD-H column with n-hexane/ethanol (90:10, v/v) as mobile phase at a flow rate of 0.8 mL min(-1) with UV detection at 220 nm. The resolution was up to 8.85. The first eluted enantiomer was (+)-furametpyr and the second eluted one was (-)-furametpyr. The effects of mobile-phase composition and column temperature on the enantioseparation were evaluated. The method was validated for linearity, repeatability, accuracy, limit of detection (LOD), and limit of quantification LOQ. LOD was 2.0 µg kg(-1) in water, 0.02 mg kg(-1) in soil, and 0.07 mg kg(-1) in rice with an LOQ of 6.7 µg kg(-1) in water, 0.07 mg kg(-1) in soil, and 0.23 mg kg(-1) in rice. The average recoveries of the pesticide in all matrices ranged from 73.1 to 101.8% for all fortification levels. The precision values associated with the analytical method, expressed as relative standard deviation (RSD) values, were below 14.0% in all matrices. The methodology was successfully applied for the enantioselective analysis of furametpyr enantiomers in real samples. © 2013 Wiley Periodicals, Inc.

United Nations Environment Programme Capacity Building Pilot Project--training and interlaboratory study on persistent organic pollutant analysis under the Stockholm Convention.

PubMed

de Boer, J; Leslie, H; van Leeuwen, S P J; Wegener, J-W; van Bavel, B; Lindström, G; Lahoutifard, N; Fiedler, H

2008-06-09

Within the framework of a United Nations Environment Programme (UNEP) Capacity Building Project for training of laboratory staff in developing countries on persistent organic pollutant (POP) analysis, an interlaboratory study was organised following an initial evaluation of the performance of laboratories (reality check) and a series of training sessions. The target compounds were polychlorinated biphenyls (PCB) and organochlorine pesticides (OCP). Seven laboratories from five countries (Ecuador, Uruguay, Kenya, Moldova, and Fiji) participated. Most of the laboratories had no experience in determining PCBs. Although chromatograms improved considerably after the training and installation of new gas chromatographic (GC) columns at participating laboratories, the level of performance in the interlaboratory study was essentially on par with the moderate performance level achieved by European POP laboratories in the 1980s. Only some individual results were within +/-20% of the target values. The relative standard deviations (R.S.D.s) in POP concentrations determined by laboratories in a sediment sample were >200% in a number of cases. The results for a certified herring sample were better with at least some R.S.D. values below 50% and most below 100%. Clean up was as one of the main sources of error. After inspection it was ascertained that training of laboratory staff and investments in simple consumables such as glassware and GC columns would help to improve the quality of the analysis more than major investments in expensive instrumentation. Creating an effective network of POP laboratories at different continents together with a series of interlaboratory studies and workshops is suggested to improve the measurements of POPs in these countries.

Multiway analysis applied to time-resolved chemiluminescence for simultaneous determination of paracetamol and codeine in pharmaceuticals.

PubMed

Mokhtari, Ali; Jafari Delouei, Nastaran; Keyvanfard, Mohsen; Abdolhosseini, Mohammad

2016-09-01

This method is based on the enhancing effect of codeine (COD) and paracetamol (PAR) on the chemiluminescence (CL) reaction of Ru(phen)3 (2+) with Ce(IV). In the batch mode, COD gives a relatively sharp peak with the highest CL intensity at 4.0 s, whereas the maximum CL intensity of the PAR appears at ~60 s after injection of Ce(IV) solution. Whole CL time profiles allowed use of the time-resolved CL data in combination with multiway calibration techniques, as multiway partial least squares (N-PLS), for the quantitative determination of both COD and PAR in binary mixtures. In this work, we found that the impact of Ce(IV) concentration on the CL intensity was different for COD and PAR. Therefore, a Ce(IV) concentration mode was added to the time and sample modes to obtain 3D data. The percent relative standard deviation (%RSD) values for 10 determinations of 1.0 × 10(-5)  mol/L of COD and 1.0 × 10(-4)  mol/L of PAR were 6.1% and 8.7%, respectively. The limit of detection (LOD) values (S/N = 3) were 0.9 × 10(-8)  mol/L and 1.0 × 10(-6)  mol/L for COD and PAR, respectively. The proposed method was successfully applied to the determination of PAR and COD in commercial pharmaceutical formulations. Acceptable recoveries (90-110%) were obtained for the quantification of these drugs in the real samples. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Stability studies of crude plant material of Bacopa monnieri and quantitative determination of bacopaside I and bacoside A by HPLC.

PubMed

Srivastava, Pratibha; Raut, Hema N; Puntambekar, Hemalata M; Desai, Anagha C

2012-01-01

Bacopa monnieri (BM) contains several dammarane-type triterpenoid saponins including bacopaside I and bacoside A. These bioactive compounds may be used as chemical markers for the quality control of different BM products used for promoting mental health and intellect. Quantification of bacopaside I and bacoside A in crude plant material of BM stored under the stability study conditions by HPLC. Crude BM samples were stored at long-term (LS; 30°C and 65% RH), accelerated (AS; 40°C and 75% RH) and real-time (RT) study conditions. HPLC of BM extracts was carried out using a LiChroCART Purospher® STAR RP-18 endcapped column along with a guard column, Purospher STAR RP 18e 4.0 4.0 mm 5 µm using a gradient of acetonitrile (A) and water containing 0.05% (v/v) orthophosphoric acid (B) at a flow rate 1.5 mL/min with UV detection at 205 nm. The linear range of bacopaside I and bacoside A was 0.2 to 1 mg/mL. With the help of a regression equation the coefficient of determination (r²) values for bacopaside I and bacoside A were found to be > 0.999 and > 0.994 respectively. Relative standard deviation (RSD) values were < 4.0 for all the concentrations injected (n = 3). The HPLC study indicated that BM samples kept under LS condition are rich in saponin contents as compared with the samples stored under AS and RT study conditions. The study indicated that BM plant material should be used fresh to obtain maximum concentration of active saponins or it should be stored under LS conditions up to 3 months. Copyright © 2012 John Wiley & Sons, Ltd.

Determination of organophosphorus pesticides in bovine tissue by an on-line coupled matrix solid-phase dispersion-solid phase extraction-high performance liquid chromatography with diode array detection method.

PubMed

Gutiérrez Valencia, Tania M; García de Llasera, Martha P

2011-09-28

A miniaturized method based on matrix solid-phase dispersion coupled to solid phase extraction and high performance liquid chromatography with diode array detection (MSPD-SPE-HPLC/DAD) was developed for the trace simultaneous determination of the following organophosphorus pesticides (OPPs) in bovine tissue: parathion-methyl, fenitrothion, parathion, chlorfenvinphos, diazinon, ethion, fenchlorphos, chlorpyrifos and carbophenothion. To perform the coupling between MSPD and SPE, 0.05 g of sample was dispersed with 0.2 g of C(18) silica sorbent and packed into a stainless steel cartridge containing 0.05 g of silica gel in the bottom. After a clean-up of high and medium polarity interferences with water and an acetonitrile:water mixture, the OPPs were desorbed from the MSPD cartridge with pure acetonitrile and directly transferred to a dynamic mixing chamber for dilution with water and preconcentration into an SPE 20 mm × 2.0 mm I.D. C(18) silica column. Subsequently, the OPPs were eluted on-line with the chromatographic mobile phase to the analytical column and the diode array detector for their separation and detection, respectively. The method was validated and yielded recovery values between 91% and 101% and precision values, expressed as relative standard deviations (RSD), which were less than or equal to 12%. Linearity was good and ranged from 0.5 to 10 μg g(-1), and the limits of detection of the OPPs were in the range of 0.04-0.25 μg g(-1). The method was satisfactorily applied to the analysis of real samples and is recommended for food control, research efforts when sample amounts are limited, and laboratories that have ordinary chromatographic instrumentation. Copyright © 2011 Elsevier B.V. All rights reserved.

Low gas flow inductively coupled plasma optical emission spectrometry for the analysis of food samples after microwave digestion.

PubMed

Nowak, Sascha; Gesell, Monika; Holtkamp, Michael; Scheffer, Andy; Sperling, Michael; Karst, Uwe; Buscher, Wolfgang

2014-11-01

In this work, the recently introduced low flow inductively coupled plasma optical emission spectrometry (ICP-OES) with a total argon consumption below 0.7 L/min is applied for the first time to the field of food analysis. One goal is the investigation of the performance of this low flow plasma compared to a conventional ICP-OES system when non-aqueous samples with a certain matrix are introduced into the system. For this purpose, arsenic is determined in three different kinds of fish samples. In addition several nutrients (K, Na, Mg, Ca) and trace metals (Co, Cu, Mn, Cd, Pb, Zn, Fe, and Ni) are determined in honey samples (acacia) after microwave digestion. The precision of the measurements is characterized by relative standard deviations (RSD) and compared to the corresponding precision values achieved using the conventional Fassel-type torch of the ICP. To prove the accuracy of the low flow ICP-OES method, the obtained data from honey samples are validated by a conventional ICP-OES. For the measurements concerning arsenic in fish, the low flow ICP-OES values are validated by conventional Fassel-type ICP-OES. Furthermore, a certified reference material was investigated with the low gas flow setup. Limits of detection (LOD), according to the 3σ criterion, were determined to be in the low microgram per liter range for all analytes. Recovery rates in the range of 96-106% were observed for the determined trace metal elements. It was proven that the low gas flow ICP-OES leads to results that are comparable with those obtained with the Fassel-type torch for the analysis of food samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Accurate determination of sulfur in gasoline and related fuel samples using isotope dilution ICP-MS with direct sample injection and microwave-assisted digestion.

PubMed

Heilmann, Jens; Boulyga, Sergei F; Heumann, Klaus G

2004-09-01

Inductively coupled plasma isotope-dilution mass spectrometry (ICP-IDMS) with direct injection of isotope-diluted samples into the plasma, using a direct injection high-efficiency nebulizer (DIHEN), was applied for accurate sulfur determinations in sulfur-free premium gasoline, gas oil, diesel fuel, and heating oil. For direct injection a micro-emulsion consisting of the corresponding organic sample and an aqueous 34S-enriched spike solution with additions of tetrahydronaphthalene and Triton X-100, was prepared. The ICP-MS parameters were optimized with respect to high sulfur ion intensities, low mass-bias values, and high precision of 32S/34S ratio measurements. For validation of the DIHEN-ICP-IDMS method two certified gas oil reference materials (BCR 107 and BCR 672) were analyzed. For comparison a wet-chemical ICP-IDMS method was applied with microwave-assisted digestion using decomposition of samples in a closed quartz vessel inserted into a normal microwave system. The results from both ICP-IDMS methods agree well with the certified values of the reference materials and also with each other for analyses of other samples. However, the standard deviation of DIHEN-ICP-IDMS was about a factor of two higher (5-6% RSD at concentration levels above 100 mircog g(-1)) compared with those of wet-chemical ICP-IDMS, mainly due to inhomogeneities of the micro-emulsion, which causes additional plasma instabilities. Detection limits of 4 and 18 microg g(-1) were obtained for ICP-IDMS in connection with microwave-assisted digestion and DIHEN-ICP-IDMS, respectively, with a sulfur background of the used Milli-Q water as the main limiting factor for both methods.

Atmospherically deposited PBDEs, pesticides, PCBs, and PAHs in western U.S. National Park fish: Concentrations and consumption guidelines

USGS Publications Warehouse

Ackerman, L.K.; Schwindt, A.R.; Simonich, S.L.M.; Koch, D.C.; Blett, T.F.; Schreck, C.B.; Kent, M.L.; Landers, D.H.

2008-01-01

Concentrations of polybrominated diphenyl ethers (PBDEs), pesticides, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons were measured in 136 fish from 14 remote lakes in 8 western U.S. National Parks/Preserves between 2003 and 2005 and compared to human and wildlife contaminant health thresholds. A sensitive (median detection limit, -18 pg/g wet weight), efficient (61% recovery at 8 ng/g), reproducible (4.1% relative standard deviation (RSD)), and accurate (7% deviation from standard reference material (SRM)) analytical method was developed and validated for these analyses. Concentrations of PCBs, hexachlorobenzene, hexachlorocyclohexanes, DDTs, and chlordanes in western U.S. fish were comparable to or lower than mountain fish recently collected from Europe, Canada, and Asia. Dieldrin and PBDE concentrations were higher than recent measurements in mountain fish and Pacific Ocean salmon. Concentrations of most contaminants in western U.S. fish were 1-6 orders of magnitude below calculated recreational fishing contaminant health thresholds. However, lake average contaminant concentrations in fish exceeded subsistence fishing cancer thresholds in 8 of 14 lakes and wildlife contaminant health thresholds for piscivorous birds in 1of 14 lakes. These results indicate that atmospherically deposited organic contaminants can accumulate in high elevation fish, reaching concentrations relevant to human and wildlife health. ?? 2008 American Chemical Society.

Neuroinflammatory Dynamics Underlie Memory Impairments after Repeated Social Defeat

PubMed Central

McKim, Daniel B.; Niraula, Anzela; Tarr, Andrew J.; Wohleb, Eric S.

2016-01-01

Repeated social defeat (RSD) is a murine stressor that recapitulates key physiological, immunological, and behavioral alterations observed in humans exposed to chronic psychosocial stress. Psychosocial stress promotes prolonged behavioral adaptations that are associated with neuroinflammatory signaling and impaired neuroplasticity. Here, we show that RSD promoted hippocampal neuroinflammatory activation that was characterized by proinflammatory gene expression and by microglia activation and monocyte trafficking that was particularly pronounced within the caudal extent of the hippocampus. Because the hippocampus is a key area involved in neuroplasticity, behavior, and cognition, we hypothesize that stress-induced neuroinflammation impairs hippocampal neurogenesis and promotes cognitive and affective behavioral deficits. We show here that RSD caused transient impairments in spatial memory recall that resolved within 28 d. In assessment of neurogenesis, the number of proliferating neural progenitor cells (NPCs) and the number of young, developing neurons were not affected initially after RSD. Nonetheless, the neuronal differentiation of NPCs that proliferated during RSD was significantly impaired when examined 10 and 28 d later. In addition, social avoidance, a measure of depressive-like behavior associated with caudal hippocampal circuitry, persisted 28 d after RSD. Treatment with minocycline during RSD prevented both microglia activation and monocyte recruitment. Inhibition of this neuroinflammatory activation in turn prevented impairments in spatial memory after RSD but did not prevent deficits in neurogenesis nor did it prevent the persistence of social avoidance behavior. These findings show that neuroinflammatory activation after psychosocial stress impairs spatial memory performance independent of deficits in neurogenesis and social avoidance. SIGNIFICANCE STATEMENT Repeated exposure to stress alters the homeostatic environment of the brain, giving rise to various cognitive and mood disorders that impair everyday functioning and overall quality of life. The brain, previously thought of as an immune-privileged organ, is now known to communicate extensively with the peripheral immune system. This brain–body communication plays a significant role in various stress-induced inflammatory conditions, also characterized by psychological impairments. Findings from this study implicate neuroimmune activation rather than impaired neurogenesis in stress-induced cognitive deficits. This idea opens up possibilities for novel immune interventions in the treatment of cognitive and mood disturbances, while also adding to the complexity surrounding the functional implications of adult neurogenesis. PMID:26937001

Different Role of CA1 5HT3 Serotonin Receptors on Memory Acquisition Deficit Induced by Total (TSD) and REM Sleep Deprivation (RSD).

PubMed

Eydipour, Zainab; Vaezi, Gholamhassan; Nasehi, Mohammad; Haeri-Rouhani, Seyed-Ali; Zarrindast, Mohammad-Reza

2017-09-01

Serotonin receptors such as 5-HT3 plays critical role in regulation of sleep, wake cycle and cognitive process. Thus, we investigated the role of CA1 5HT3 serotonin receptors in memory acquisition deficit induced by total sleep deprivation (TSD; for 24 hour) and REM sleep deprivation (RSD; for 24 hour). Pain perception and locomotor activity were also assessed as factors that may affect the memory process. Modified water box and multi-platform apparatus were used to induce TSD or RSD, respectively. Passive avoidance, hot plate and open field devices were used for assessment of memory acquisition, pain and locomotor activity, respectively. Totally, 152 male Wistar rats were used in the study. Pre-training, intra-CA1 injection of 5-HT3 receptor agonist Chlorophenylbiguanide (Mchl; 0.01 and 0.001 µg/rat; P < 0.001) and antagonist Y-25130 (0.1 µg/rat; P < 0.001) reduced memory acquisition and did not alter pain response, while higher dose of both drugs increased locomotor activity in normal rats. Both TSD and RSD reduced memory acquisition (P < 0.001) and did not alter locomotor activity, while TSD (P < 0.001) but not RSD induced analgesia effect. The amnesia induced by TSD was restored by subthreshold dose of Y25130 (0.001 µg/rat; P < 0.001) but not Mchl (0.0001 µg/rat), while both drugs reversed TSD-induced analgesia effect (P < 0.01 for Mchl and P < 0.05 for Y25130), and Y25130 increased locomotor activity in TSD rats (P < 0.05). In RSD rats, subthreshold dose of both drugs did not alter memory acquisition deficit and increased locomotor activity (P < 0.001 for Mchl and P < 0.01 for Y25130), while the Y25130 (P < 0.001), but not Mchl induced analgesia in the RSD rats. Based on the above data, CA1 5HT3 receptors seem to play a critical role in cognitive and non-cognitive behaviors induced by TSD and RSD.

An electrochemical sensor prepared by sonochemical one-pot synthesis of multi-walled carbon nanotube-supported cobalt nanoparticles for the simultaneous determination of paracetamol and dopamine.

PubMed

Kutluay, Aysegul; Aslanoglu, Mehmet

2014-08-11

Multi-walled carbon nanotubes (MWCNTs) functionalized by cobalt nanoparticles were obtained using a single step chemical deposition method in an ultrasonic bath. The composite material was characterized using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The electroactivity of the cobalt-functionalized MWCNTs was assessed in respect to the electrooxidation of paracetamol (PAR) and dopamine (DA). It was found that the carbon nanotube supported cobalt nanoparticles have significantly higher catalytic properties. The proposed electrode has been applied for the simultaneous determination of PAR and DA. The modified electrode could resolve the overlapped voltammetric waves of PAR and DA into two well-defined voltammetric peaks with peak to peak separation of about 203 mV. On the other hand, the presence of potential drug interfering compounds AA and UA did not affect the voltammetric responses of PAR and DA. The current of oxidation peaks showed a linear dependent on the concentrations of PAR and DA in the range of 5.2×10(-9)-4.5×10(-7) M (R(2)=0.9987) and 5.0×10(-8)-3.0×10(-6) M (R(2)=0.9999), respectively. The detection limits of 1.0×10(-9) M and 1.5×10(-8) M were obtained for PAR and DA, respectively. The proposed electrode showed good stability (peak current change: 4.9% with and RSD of 2.6% for PAR; 5.5% with and RSD of 3.0% for DA over 3 weeks), reproducibility (RSD 2.3% for PAR and RSD 1.5% for DA), repeatability (RSD 2.25% for PAR and RSD 2.50% for DA) and high recovery (99.7% with an RSD of 1.3% for PAR; 100.8% with an RSD of 1.8% for DA). The proposed method was successfully applied to the determination of PAR and DA in pharmaceuticals. Copyright © 2014. Published by Elsevier B.V.

Molecular mechanisms of repeated social defeat-induced glucocorticoid resistance: Role of microRNA.

PubMed

Jung, Seung Ho; Wang, Yufen; Kim, Taewan; Tarr, Andrew; Reader, Brenda; Powell, Nicole; Sheridan, John F

2015-02-01

Glucocorticoid (GC) resistance is a severe problem associated with various inflammatory diseases. Previous studies have shown that repeated social stress induces GC resistance in innate immune cells, but the underlying molecular mechanisms have not been fully elucidated. Therefore, the purpose of this study was to examine potential underlying molecular mechanism(s) of repeated social defeat (RSD) stress on GC resistance in splenic macrophages. It was hypothesized that mRNA expression of receptors for GC and nuclear translocating-associated regulators in splenic macrophages would be affected by RSD, and that these changes would be associated with epigenetic modification. The data showed that the mRNA expression of GC and mineralocorticoid receptors were significantly decreased in splenic macrophages by RSD. RSD also induced a significantly decreased mRNA expression in FK506-binding protein 52 (FKBP52), consequently resulting in a significantly increased ratio of FKBP51 to FKBP52. Moreover, DNA methyltransferases 3a and 3b showed a significant decrease in their mRNA expression in the RSD group as did mRNA expression of histone deacetyltransferase 2. The RSD group also showed a significantly reduced quantity of methylated DNA in splenic macrophages. Based on microRNA (miRNA) profiling data, it was determined that RSD induced significantly increased expression of 9 different miRNAs that were predicted to interact with mRNAs of the GC receptor (6 miRNAs), mineralocorticoid receptor (3 miRNAs) and FKBP52 (2 miRNAs). Spearman correlation analysis revealed significantly strong correlations between the expression of 2 miRNAs and their target mRNA expression for GC receptors. Among these miRNAs, we verified direct effects of miRNA-29b and -340 overexpression on mRNA expression of GC receptors in L929 cells. The overexpression of miRNA-29b or -340 in L929 cells significantly reduced LPS-induced overexpression of GC receptors. In conclusion, this study provides evidence that epigenetic regulation, such as DNA methylation and miRNA expression, may play a role in the RSD-induced GC resistance that we have observed in splenic macrophages. Copyright © 2014 Elsevier Inc. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shedlock, Daniel; Dugan, Edward T.; Jacobs, Alan M.

X-ray backscatter radiography by selective detection (RSD) is a field tested and innovative approach to non-destructive evaluation (NDE). RSD is an enhanced single-side x-ray Compton backscatter imaging (CBI) technique which selectively detects scatter components to improve image contrast and quality. Scatter component selection is accomplished through a set of specially designed detectors with fixed and movable collimators. Experimental results have shown that this NDE technique can be used to detect boric acid deposition on a metallic plate through steel foil reflective insulation commonly covering reactor pressure vessels. The current system is capable of detecting boric acid deposits with sub-millimeter resolution,more » through such insulating materials. Industrial systems have been built for Lockheed Martin Space Co. and NASA. Currently the x-ray backscatter RSD scanning systems developed by the University of Florida are being used to inspect the spray-on foam insulation (SOFI) used on the external tank of the space shuttle. RSD inspection techniques have found subsurface cracking in the SOFI thought to be responsible for the foam debris which separated from the external tank during the last shuttle launch. These industrial scanning systems can be customized for many applications, and a smaller, lighter, more compact unit design is being developed. The smaller design is approximately four inches wide, three inches high, and about 12 inches in length. This smaller RSD system can be used for NDE of areas that cannot be reached with larger equipment. X-ray backscatter RSD is a proven technology that has been tested on a wide variety of materials and applications. Currently the system has been used to inspect materials such as aluminum, plastics, honeycomb laminates, reinforced carbon composites, steel, and titanium. The focus of RSD is for one-sided detection for applications where conventional non-destructive examination methods either will not work or give poor results. Acquired images have clearly shown, for a variety of conditions, that proper selection of x-ray field scatter components leads to a significant improvement in image quality and contrast. Improvements are significant enough in some cases that objects not visible to conventional CBI or transmission radiography become readily discernable with RSD. (authors)« less

Critical role of CA1 muscarinic receptors on memory acquisition deficit induced by total (TSD) and REM sleep deprivation (RSD).

PubMed

Javad-Moosavi, Bibi-Zahra; Vaezi, Gholamhassan; Nasehi, Mohammad; Haeri-Rouhani, Seyed-Ali; Zarrindast, Mohammad-Reza

2017-10-03

Despite different theories regarding sleep physiological function, an overall census indicates that sleep is useful for neural plasticity which eventually strengthens cognition and brain performance. Different studies show that sleep deprivation (SD) leads to impaired learning and hippocampus dependent memory. According to some studies, cholinergic system plays an important role in sleep (particularly REM sleep), learning, memory, and its retrieval. So this study has been designed to investigate the effect of CA1 Cholinergic Muscarinic Receptors on memory acquisition deficit induced by total sleep deprivation (TSD) and REM sleep deprivation (RSD). A modified water box (locomotor activity may be provide a limiting factor in this method of SD) or multiple platforms were used for induction of TSD or RSD, respectively. Inhibitory passive avoidance apparatus has been used to determine the effects of SD and its changes by physostigmine (as cholinesterase inhibitor) or scopolamine (muscarinic receptor antagonist) on memory formation. Because locomotor activity and pain perception induce critical roles in passive avoidance memory formation, we also measured these factors by open field and hot-plate instruments, respectively. The results showed that TSD and RSD for 24 hours impaired memory formation but they did not alter locomotor activity. TSD also induced analgesia effect, but RSD did not alter it. Intra-CA1 injection of physostigmine (0.0001μg/rat) and scopolamine (0.01μg/rat) did not alter memory acquisition in the sham-TSD or sham-RSD, by themselves. Moreover, intra-CA1 injection of sub-threshold dose of physostigmine (0.0001μg/rat) and scopolamine (0.01μg/rat) could restore the memory acquisition deficit induced by RSD, while scopolamine could restore TSD-induced amnesia. Both drugs reversed analgesia induced by TSD. None of previous interventions altered locomotor activity. According to this study, CA1 cholinergic muscarinic receptors play an important role in amnesia induced by both TSD and RSD. However further studies are needed for showing cellular and molecular mechanisms of surprising result of similar pharmacological effects using compounds with opposite profiles. Copyright © 2016. Published by Elsevier Inc.

Molecular Mechanisms of Repeated Social Defeat-Induced Glucocorticoid Resistance: Role of microRNA

PubMed Central

Jung, Seung Ho; Wang, Yufen; Kim, Taewan; Tarr, Andrew; Reader, Brenda; Powell, Nicole; Sheridan, John F.

2014-01-01

Glucocorticoid (GC) resistance is a severe problem associated with various inflammatory diseases. Previous studies have shown that repeated social stress induces GC resistance in innate immune cells, but the underlying molecular mechanisms have not been fully elucidated. Therefore, the purpose of this study was to examine potential underlying molecular mechanism(s) of repeated social defeat (RSD) stress on GC resistance in splenic macrophages. It was hypothesized that mRNA expression of receptors for GC and nuclear translocating-associated regulators in splenic macrophages would be affected by RSD, and that these changes would be associated with epigenetic modification. The data showed that the mRNA expression of GC and mineralocorticoid receptors were significantly decreased in splenic macrophages by RSD. RSD also induced a significantly decreased mRNA expression in FK506-binding protein 52 (FKBP52), consequently resulting in a significantly increased ratio of FKBP51 to FKBP52. Moreover, DNA methyltransferases 3a and 3b showed a significant decrease in their mRNA expression in the RSD group as did mRNA expression of histone deacetyltransferase 2. The RSD group also showed a significantly reduced quantity of methylated DNA in splenic macrophages. Based on microRNA (miRNA) profiling data, it was determined that RSD induced significantly increased expression of 9 different miRNAs that were predicted to interact with mRNAs of the GC receptor (6 miRNAs), mineralocorticoid receptor (3 miRNAs) and FKBP52 (2 miRNAs). Spearman correlation analysis revealed significantly strong correlations between the expression of 2 miRNAs and their target mRNA expression for GC receptors. Among these miRNAs, we verified direct effects of miRNA-29b and -340 overexpression on mRNA expression of GC receptors in L929 cells. The overexpression of miRNA-29b or -340 in L929 cells significantly reduced LPS-induced overexpression of GC receptors. In conclusion, this study provides evidence that epigenetic regulation, such as DNA methylation and miRNA expression, may play a role in the RSD-induced GC resistance that we have observed in splenic macrophages. PMID:25317829

The rationale for the optimum efficiency of columns packed with new 1.9μm fully porous Titan-C18 particles-a detailed investigation of the intra-particle diffusivity.

PubMed

Gritti, Fabrice; Guiochon, Georges

2014-08-15

In a previous report, it was reported that columns packed with fully porous 1.9μm Titan-C18 particles provided a minimum reduced plate height as small as 1.7 for the most retained compound (n-octanophenone) under RPLC conditions. These particles are characterized by a relatively narrow size distribution with a relative standard deviation (RSD) of only 10%. A column packed with classical 5μm Symmetry-C18 particles, used as a reference RPLC column, generated a minimum reduced plate height of 2.1 for the same retained compound. This work demonstrates that this was due to an unusually low intra-particle diffusivity across these particles, which leads to a small longitudinal diffusion coefficient along the column. The demonstration is based on the combination of accurate measurements of the height equivalent to a theoretical plate (HETP), inverse size exclusion chromatography (ISEC), peak parking (PP), and minor disturbance method (MDM) experiments. The experimental results show that the reduced eddy dispersion HETP term (A=0.8 for a reduced velocity of 5), the internal particle porosity (ϵp=0.35), and the enrichment of acetonitrile in the pore volume (75% acetonitrile in the bulk, 85% inside the mesoporous volume) are identical on both the Titan-C18 and Symmetry-C18 columns. The difference between the internal structures of these two brands of RPLC-C18 fully porous particles lies in the values of the internal obstruction factor γp, which is 0.42 for the Symmetry-C18 but only 0.26 for the Titan-C18 particles. This is in part related to the diffusion hindrance due to the small average pore size of the Titan-C18 particles, around 59Å versus 77Å for Symmetry-C18 particles. A simple model of constriction along diffusion paths having the shape of a truncated cone suggests that the width of the pore size distribution (RSD of 30% and 20% for Titan-C18 and Symmetry-C18 particles) is mostly responsible for the difference in their obstruction factors. Copyright © 2014 Elsevier B.V. All rights reserved.

Facile LC-UV methods for simultaneous monitoring of ciprofloxacin and rosuvastatin in API, formulations and human serum.

PubMed

Arayne, M Saeed; Sultana, Najma; Tabassum, Arman

2015-02-01

An efficient, selective and cost-effective liquid chromatographic assay was developed and validated for the simultaneous quantification of ciprofloxacin and rosuvastatin in Active Pharmaceutical Ingredients (API), pharmaceutical formulations and in human serum. The chromatographic system consisted of mobile phase methanol-water, 90:10 v/v at pH 3.0 adjusted with o-phosphoric acid, pumped at 1.0 mL/min through a prepacked Purospher Star C18 (5 µm, 25 × 0.46 cm) column and effluent was monitored at the isosbestic point (255 nm) as well as at the λmax of individual drugs (243 and 271 nm). The method was validated over a linear concentration range of 0.25-15 µg/mL for ciprofloxacin and 0.33-20 µg/mL for rosuvastatin (r(2)  ≥ 0.999). The ranges of reliable response (limits of detection and quantitation) for ciprofloxacin were 3-15 and 9-45 ng/mL and 17-29 and 52-88 ng/mL, respectively, for rosuvastatin in all API, pharmaceutical formulations and human serum. Analytical recovery from human serum was >98% and relative standard deviation (RSD) was <2. The accuracies were 97.13-102.55 and 97.41-101.31% and precisions in RSD were 0.04-1.90 and 0.02-1.23% for ciprofloxacin and rosuvastatin, respectively. No matrix interferences, ion suppression/enhancement and carry-over were detected. The total assay run time was less than 5 min. In another study, for optimum performance the detector was programmed for multiwavelength scanning at the absorption maxima of each component. Consequently, the linearity range was improved and limit of detection and quantitation values were down to 1-4 and 4-12 ng/mL for ciprofloxacin and 3-5 and 9-15 ng/mL for rosuvastatin, respectively. The validation parameters fitted ICH guidelines through the isosbestic and individual λmax approach. The small sample volume and simplicity of preparation make this method suitable for use in human serum samples, pharmaceutical formulations, quality control, drug-drug interaction studies, clinical laboratories, drug research centers and forensic medical centers. Copyright © 2014 John Wiley & Sons, Ltd.

Determination of total and electrolabile copper in agricultural soil by using disposable modified-carbon screen-printed electrodes.

PubMed

Faucher, Stéphane; Cugnet, Cyril; Authier, Laurent; Lespes, Gaëtane

2014-02-01

The objective of the study is to evaluate modified-carbon screen-printed working electrodes (SPE) combined with square wave anodic stripping voltammetry (SWASV) to determine electrolabile and total copper in soils with the perspective to assess the environmental hazard resulting from copper anthropogenic contamination. The voltammetric method was investigated using a mineralized certified reference soil such that it can be assumed that the copper was totally under electrolabile form in the solution of mineralized soil. In optimal conditions, a copper recovery of 97% and a relative standard deviation (RSD) of 9% were found. The limits of detection and quantification for copper were 0.4 and 1.3 μg L(-1), respectively. Finally, the method was applied on soil leachates, which allowed evaluating the cupric transfer from the soil to the leachates and quantifying the electrolabile copper part in leachates.

Post-chemiluminescence determination of chloramphenicol based on luminol-potassium periodate system.

PubMed

Yang, Xiao Feng; Li, Nian Bing; Luo, Hong Qun

2012-01-01

A post-chemiluminescence (PCL) phenomenon was observed when chloramphenicol was injected into a mixture of luminol and potassium periodate after the chemiluminescence (CL) reaction of luminol-potassium periodate had finished. The possible reaction mechanism was proposed based on studies of the CL kinetic characteristics, the CL spectra, the fluorescence spectra and the UV-vis absorption spectra of the related substances. Based on the PCL reaction, a rapid and sensitive method for the determination of chloramphenicol was established. The linear response range was 6.0 × 10(-7) -1.0 × 10(-5) mol/L, with a correlation coefficient of 0.9986. The relative standard deviation (RSD) for 5.0 × 10(-6) mol/L chloramphenicol was 2.3% (n = 11). The detection limit was 1.6 × 10(-7) mol/L. The method has been applied to the determination of chloramphenicol in pharmaceutical samples with satisfactory results. Copyright © 2011 John Wiley & Sons, Ltd.

Detection of Scopolamine Hydrobromide via Surface-enhanced Raman Spectroscopy.

PubMed

Bao, Lin; Sha, Xuan-Yu; Zhao, Hang; Han, Si-Qin-Gao-Wa; Hasi, Wu-Li-Ji

2017-01-01

Surface-enhanced Raman spectroscopy (SERS) was used to measure scopolamine hydrobromide. First, the Raman characteristic peaks of scopolamine hydrobromide were assigned, and the characteristic peaks were determined. The optimal aggregation agent was potassium iodide based on a comparative experimental study. Finally, the SERS spectrum of scopolamine hydrobromide was detected in aqueous solution, and the semi-quantitative analysis and the recovery rate were determined via a linear fitting. The detection limit of scopolamine hydrobromide in aqueous solution was 0.5 μg/mL. From 0 - 10 μg/mL, the curve of the intensity of the Raman characteristic peak of scopolamine hydrobromide at 1002 cm -1 is y = 4017.76 + 642.47x. The correlation coefficient was R 2 = 0.983, the recovery was 98.5 - 109.7%, and the relative standard deviation (RSD) was about 5.5%. This method is fast, accurate, non-destructive and simple for the detection of scopolamine hydrobromide.

Carboxylated multiwalled carbon nanotubes/polydimethylsiloxane, a new coating for 96-blade solid-phase microextraction for determination of phenolic compounds in water.

PubMed

Kueseng, Pamornrat; Pawliszyn, Janusz

2013-11-22

A new thin-film, carboxylated multiwalled carbon nanotubes/polydimethylsiloxane (MWCNTs-COOH/PDMS) coating was developed for 96-blade solid-phase microextraction (SPME) system followed by high performance liquid chromatography with ultraviolet detection (HPLC-UV). The method provided good extraction efficiency (64-90%) for three spiked levels, with relative standard deviations (RSD)≤6%, and detection limits between 1 and 2 μg/L for three phenolic compounds. The MWCNTs-COOH/PDMS 96-blade SPME system presents advantages over traditional methods due to its simplicity of use, easy coating preparation, low cost and high sample throughput (2.1 min per sample). The developed coating is reusable for a minimum of 110 extractions with good extraction efficiency. The coating provided higher extraction efficiency (3-8 times greater) than pure PDMS coatings. Copyright © 2013 Elsevier B.V. All rights reserved.

Automated solid-phase extraction workstations combined with quantitative bioanalytical LC/MS.

PubMed

Huang, N H; Kagel, J R; Rossi, D T

1999-03-01

An automated solid-phase extraction workstation was used to develop, characterize and validate an LC/MS/MS method for quantifying a novel lipid-regulating drug in dog plasma. Method development was facilitated by workstation functions that allowed wash solvents of varying organic composition to be mixed and tested automatically. Precision estimates for this approach were within 9.8% relative standard deviation (RSD) across the calibration range. Accuracy for replicate determinations of quality controls was between -7.2 and +6.2% relative error (RE) over 5-1,000 ng/ml(-1). Recoveries were evaluated for a wide variety of wash solvents, elution solvents and sorbents. Optimized recoveries were generally > 95%. A sample throughput benchmark for the method was approximately equal 8 min per sample. Because of parallel sample processing, 100 samples were extracted in less than 120 min. The approach has proven useful for use with LC/MS/MS, using a multiple reaction monitoring (MRM) approach.

On-line concentration and determination of all-trans- and 13-cis- retinoic acids in rabbit serum by application of sweeping technique in micellar electrokinetic chromatography.

PubMed

Zhao, Yongxi; Kong, Yu; Wang, Bo; Wu, Yayan; Wu, Hong

2007-03-30

A simple and rapid micellar electrokinetic chromatography (MEKC) method with UV detection was developed for the simultaneous separation and determination of all-trans- and 13-cis-retinoic acids in rabbit serum by on-line sweeping concentration technique. The serum sample was simply deproteinized and centrifuged. Various parameters affecting sample enrichment and separation were systematically investigated. Under optimal conditions, the analytes could be well separated within 17min, and the relative standard deviations (RSD) of migration times and peak areas were less than 3.4%. Compared with the conventional MEKC injection method, the 18- and 19-fold improvements in sensitivity were achieved, respectively. The proposed method has been successfully applied to the determination of all-trans- and 13-cis-retinoic acids in serum samples from rabbits and could be feasible for the further pharmacokinetics study of all-trans-retinoic acid.

[Study on the determination of 14 inorganic elements in coffee by inductively coupled plasma mass spectrometry].

PubMed

Nie, Xi-Du; Fu, Liang

2013-07-01

Samples of coffee were digested by microwave digestion, and inorganic elements amounts of Na, Mg, P, Ca, Cr, Mn, Fe, Co, Cu, Zn, As, Se, Mo and Pb in sample solutions were determined by inductively coupled plasma mass spectrometry (ICP-MS). HNO3 + H2O2 was used to achieve the complete decomposition of the organic matrix in a closed-vessel microwave oven. The working parameters of the instrument were optimized. The results showed that the relative standard deviation (RSD) was less than 3.84% for all the elements, and the recovery was found to be 92.00% -106.52% by adding standard recovery experiment. This method was simple, sensitive and precise and can perform simultaneous multi-elements determination of coffee, which could satisfy the sample examination request and provide scientific rationale for determining inorganic elements of coffee.

Analysis of polycyclic aromatic hydrocarbons in water and beverages using membrane-assisted solvent extraction in combination with large volume injection-gas chromatography-mass spectrometric detection.

PubMed

Rodil, Rosario; Schellin, Manuela; Popp, Peter

2007-09-07

Membrane-assisted solvent extraction (MASE) in combination with large volume injection-gas chromatography-mass spectrometry (LVI-GC-MS) was applied for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. The MASE conditions were optimized for achieving high enrichment of the analytes from aqueous samples, in terms of extraction conditions (shaking speed, extraction temperature and time), extraction solvent and composition (ionic strength, sample pH and presence of organic solvent). Parameters like linearity and reproducibility of the procedure were determined. The extraction efficiency was above 65% for all the analytes and the relative standard deviation (RSD) for five consecutive extractions ranged from 6 to 18%. At optimized conditions detection limits at the ng/L level were achieved. The effectiveness of the method was tested by analyzing real samples, such as river water, apple juice, red wine and milk.

Highly sensitive surface enhanced Raman scattering substrates based on Ag decorated Si nanocone arrays and their application in trace dimethyl phthalate detection

NASA Astrophysics Data System (ADS)

Zuo, Zewen; Zhu, Kai; Ning, Lixin; Cui, Guanglei; Qu, Jun; Cheng, Ying; Wang, Junzhuan; Shi, Yi; Xu, Dongsheng; Xin, Yu

2015-01-01

Wafer-scale three-dimensional (3D) surface enhancement Raman scattering (SERS) substrates were prepared using the plasma etching and ion sputtering methods that are completely compatible with well-established silicon device technologies. The substrates are highly sensitive with excellent uniformity and reproducibility, exhibiting an enhancement factor up to 1012 with a very low relative standard deviation (RSD) around 5%. These are attributed mainly to the uniform-distributed, multiple-type high-density hot spots originating from the structural characteristics of Ag nanoparticles (NPs) decorated Si nanocone (NC) arrays. We demonstrate that the trace dimethyl phthalate (DMP) at a concentration of 10-7 M can be well detected using this SERS substrate, showing that the AgNPs-decorated SiNC arrays can serve as efficient SERS substrates for phthalate acid esters (PAEs) detection with high sensitivity.

Rapid and simple preparation of rhodamine 6G loaded HY zeolite for highly selective nitrite detection

NASA Astrophysics Data System (ADS)

Viboonratanasri, Duangkamon; Pabchanda, Suwat; Prompinit, Panida

2018-05-01

In this study, a simple, rapid and relatively less toxic method for rhodamine 6G dye adsorption on hydrogen-form Y-type zeolite for highly selective nitrite detection was demonstrated. The adsorption behavior was described by Langmuir isotherm and the adsorption process reached the equilibrium promptly within a minute. The developed test papers characterized by fluorescence technique display high sensing performance with wide working range (0.04-20.0 mg L-1) and high selectivity. The test papers show good reproducibility with relative standard deviation (RSD) of 7% for five replicated determinations of 3 mg L-1 of nitrite. The nitrite concentration determined by using the test paper was in the same range as using ion chromatography within a 95% confidence level. The test papers offer advantages in terms of low cost and practical usage enabling them to be a promising candidate for nitrite sensor in environmental samples, food, and fertilizers.

Development and characterization of a FIA system for selective assay of L-ascorbic acid in food samples.

PubMed

Vig, Attila; Igloi, Attila; Adanyi, Nora; Gyemant, Gyongyi; Csutoras, Csaba; Kiss, Attila

2010-10-01

An amperometric detector and an enzymatic reaction were combined for the measurement of L-ascorbic acid. The enzyme cell (containing immobilized ascorbate oxidase) was connected to a flow injection analyzer (FIA) system with a glassy carbon electrode as an amperometric detector. During optimization and measurements two sample injectors were used, one before and one after the enzyme cell, thus eliminating the background interferences. Subtraction of the signal area given in the presence of enzyme from the one given in the absence of enzyme was applied for measuring analyte concentrations and calibration at 400 mV. Analysis capacity of system is 25 samples/hour. The relative standard deviation (RSD) was below 5% (5 times repeated, 400 μmol/L conc.), linearity up to 400 μmol/L, limit of detection (LOD) 5 μmol/L, fitting of calibration curve in 25-400 μmol/L range was R (2) = 0.99.

Optimization of β-cyclodextrin cross-linked polymer for monitoring of quercetin

NASA Astrophysics Data System (ADS)

Zhu, Xiashi; Ping, Wenhui

2014-11-01

A novel method for the separation/analysis of quercetin was described, which was based on the investigation of the inclusion interactions of β-cyclodextrin cross-linked polymer (β-CDCP) with quercetin (Qu) and the adsorption behavior of Qu on β-CDCP. The inclusion interaction of β-CDCP with Qu was studied through FTIR, TGA and 13C NMR. Under the optimum conditions, the preconcentration factor of the proposed method was approximately 8.8, the β-CDCP could be used repeatedly for 30 times and offered better recovery. The linear range, limit of detection (LOD) and the relative standard deviation (RSD) was found to be 0.10-12.0 μg mL-1, 4.6 ng mL-1 and 3.10% (n = 3, c = 2.0 μg mL-1) respectively. This technique had been successfully applied to the determination of Qu in real samples.

Gas chromatographic analysis of fatty acid methyl esters of milk fat by an ionic liquid derived from L-phenylalanine as the stationary phase.

PubMed

Mendoza, Laura González; González-Álvarez, Jaime; Gonzalo, Carla Fernández; Arias-Abrodo, Pilar; Altava, Belén; Luis, Santiago V; Burguete, Maria Isabel; Gutiérrez-Álvarez, María Dolores

2015-10-01

A Gas Chromatography (GC) method has been developed for the separation and characterization of the different fatty acids in anhydrous milk fat (AMF) by means of an ionic liquid stationary phase, characterized by a monocationic imidazolium salt derived from L-phenylalanine. The inner surface of a fused silica capillary column was modified using this ionic liquid functionality and 3-aminopropyldiethoxymethyl silane. This coated GC column, which exhibited good thermal stability (270°C) and good efficiency (2700 plates/m), has been characterized using the Abraham solvation parameter model. The intra-day and inter-day precision of the method have been evaluated, obtaining relative standard deviations (RSD) from 0.99% to 4.0% and from 2.8% to 9.2%, respectively. Furthermore, recoveries from 90% and 99% have been achieved. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthesis and application of acrylamide-maleic anhydride copolymer for solid phase extraction

NASA Astrophysics Data System (ADS)

Teng, Xiaoxiao; Niu, Yabo; Xie, Zhihai; Cai, Qing

2018-03-01

A new absorbent of acrylamide-maleic anhydride copolymer (PAMMA) for preconcentration of metal ions was synthesized. This PAMMA was applied for enrichment and determination of Al3+, Cu2+, Cd2+ and Pb2+ in table salt by ICP-OES. The maximum uptake capacities of PAMMA were 6.49, 5.84, 5.34 and 7.49 mg g‑1 for Al3+, Cu2+, Cd2+ and Pb2+, respectively. The limit of detection was 0.31, 0.26, 0.43, and 0.12 μg L‑1, and the RSD (relative standard deviations, n=6) was 1.5%, 3.7%, 3.0% and 2.6% for Al3+, Cu2+, Cd2+ and Pb2+, respectively. The presented method was used for simultaneous detecting of Al3+, Cu2+, Cd2+ and Pb2+ in table salt with the recoveries from 95.0% to 103%.

Application of catalytic adsorptive stripping voltammetry of the cobalt-alpha-benzil dioxime complex to analysis of cobalt traces in metallic zinc.

PubMed

Bobrowski, A

1994-05-01

The catalytic adsorptive stripping voltammetric method with alpha-benzil dioxime and nitrite affords numerous advantages in cobalt determination. The detailed conditions of the determination of the cobalt traces in metallic zinc by catalytic adsorptive stripping voltammetry have been investigated. Both the linear sweep and the differential pulse stripping modes can be used with similar sensitivity. Possible interferences by Mn, Pb, Cu, Ni and Fe are evaluated. In the presence of 5 x 10(5) fold excess of Zn the linear dependence of the cobalt CASV peak current on concentration ranged from 0.05 mug/l to 3 mug/l. Optimal conditions include the accumulation potential of -0.65 V and the accumulation time of 10 sec. The results of the determination of 10(-5)% level of Co in the metallic zinc showed good reproducibility (relative standard deviation, RSD = 0.07) and reliability.

Speciation of organic and inorganic selenium in selenium-enriched rice by graphite furnace atomic absorption spectrometry after cloud point extraction.

PubMed

Sun, Mei; Liu, Guijian; Wu, Qianghua

2013-11-01

A new method was developed for the determination of organic and inorganic selenium in selenium-enriched rice by graphite furnace atomic absorption spectrometry detection after cloud point extraction. Effective separation of organic and inorganic selenium in selenium-enriched rice was achieved by sequentially extracting with water and cyclohexane. Under the optimised conditions, the limit of detection (LOD) was 0.08 μg L(-1), the relative standard deviation (RSD) was 2.1% (c=10.0 μg L(-1), n=11), and the enrichment factor for selenium was 82. Recoveries of inorganic selenium in the selenium-enriched rice samples were between 90.3% and 106.0%. The proposed method was successfully applied for the determination of organic and inorganic selenium as well as total selenium in selenium-enriched rice. Copyright © 2013 Elsevier Ltd. All rights reserved.

Determination of anionic surface active agents using silica coated magnetite nanoparticles modified with cationic surfactant aggregates.

PubMed

Pena-Pereira, Francisco; Duarte, Regina M B O; Trindade, Tito; Duarte, Armando C

2013-07-19

The development of a novel methodology for extraction and preconcentration of the most commonly used anionic surface active agents (SAAs), linear alkylbenzene sulfonates (LAS), is presented herein. The present method, based on the use of silica-magnetite nanoparticles modified with cationic surfactant aggregates, was developed for determination of C10-C13 LAS homologues. The proposed methodology allowed quantitative recoveries of C10-C13 LAS homologues by using a reduced amount of magnetic nanoparticles. Limits of detection were in the range 0.8-1.9μgL(-1) for C10-C13 LAS homologues, while the repeatability, expressed as relative standard deviation (RSD), ranged from 2.0 to 3.9% (N=6). Finally, the proposed method was successfully applied to the analysis of a variety of natural water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Individual Component Map of Rotatory Strength (ICM-RS) and Rotatory Strength Density (RSD) plots as analysis tools of circular dicroism spectra of complex systems.

PubMed

Chang, Le; Baseggio, Oscar; Sementa, Luca; Cheng, Daojian; Fronzoni, Giovanna; Toffoli, Daniele; Aprà, Edoardo; Stener, Mauro; Fortunelli, Alessandro

2018-06-13

We introduce Individual Component Maps of Rotatory Strength (ICM-RS) and Rotatory Strength Density (RSD) plots as analysis tools of chiro-optical linear response spectra deriving from time-dependent density functional theory (TDDFT) simulations. ICM-RS and RSD allow one to visualize the origin of chiro-optical response in momentum or real space, including signed contributions and therefore highlighting cancellation terms that are ubiquitous in chirality phenomena, and should be especially useful in analyzing the spectra of complex systems. As test cases, we use ICM-RS and RSD to analyze circular dichroism spectra of selected (Ag-Au)30(SR)18 monolayer-protected metal nanoclusters, showing the potential of the proposed tools to derive insight and understanding, and eventually rational design, in chiro-optical studies of complex systems.

Impact of three-phase bone scintigraphy on the diagnosis and treatment of complex regional pain syndrome type I or reflex sympathetic dystrophy.

PubMed

Shehab, Dia; Elgazzar, Abdelhamid; Collier, B David; Naddaf, Sleiman; Al-Jarallah, Khalid; Omar, Abdelmoneim; Al-Mutairy, Moudi

2006-01-01

To determine the impact of three-phase bone scintigraphy (TPBS) on the diagnosis and management of complex regional pain syndrome type I (CRPSI) or reflex sympathetic dystrophy (RSD). Twenty consecutive patients with a recent clinical evidence of CRPSI were referred for TPBS as part of their routine management plan. All patients underwent neurological examinations with special attention to the evaluation of clinical features of vasomotor, sudomotor, motor and sensory dysfunction. Patients were followed prospectively. When both the clinical and TPBS results supported the diagnosis of CRPSI, patients were started on treatment. Of the 20 patients, TPBS supported the diagnosis of RSD in 9 who were treated with steroids and physiotherapy. Complete follow-up was available for 7 of them and all had a satisfactory response to treatment. For the remaining 11 patients RSD was diagnosed clinically but not confirmed by TPBS. On follow-up there was no evidence that TPBS failed to identify RSD in these 11 patients. The results indicate that TPBS confirmed the clinical diagnosis of RSD, and, more importantly, had a significant impact on its management.

Social defeat promotes a reactive endothelium in a brain region-dependent manner with increased expression of key adhesion molecules, selectins and chemokines associated with the recruitment of myeloid cells to the brain.

PubMed

Sawicki, C M; McKim, D B; Wohleb, E S; Jarrett, B L; Reader, B F; Norden, D M; Godbout, J P; Sheridan, J F

2015-08-27

Repeated social defeat (RSD) in mice causes myeloid cell trafficking to the brain that contributes to the development of prolonged anxiety-like behavior. Myeloid cell recruitment following RSD occurs in regions where neuronal and microglia activation is observed. Thus, we hypothesized that crosstalk between neurons, microglia, and endothelial cells contributes to brain myeloid cell trafficking via chemokine signaling and vascular adhesion molecules. Here we show that social defeat caused an exposure- and brain region-dependent increase in several key adhesion molecules and chemokines involved in the recruitment of myeloid cells. For example, RSD induced distinct patterns of adhesion molecule expression that may explain brain region-dependent myeloid cell trafficking. VCAM-1 and ICAM-1 mRNA expression were increased in an exposure-dependent manner. Furthermore, RSD-induced VCAM-1 and ICAM-1 protein expression were localized to the vasculature of brain regions implicated in fear and anxiety responses, which spatially corresponded to previously reported patterns of myeloid cell trafficking. Next, mRNA expression of additional adhesion molecules (E- and P-selectin, PECAM-1) and chemokines (CXCL1, CXCL2, CXCL12, CCL2) were determined in the brain. Social defeat induced an exposure-dependent increase in mRNA levels of E-selectin, CXCL1, and CXCL2 that increased with additional days of social defeat. While CXCL12 was unaffected by RSD, CCL2 expression was increased by six days of social defeat. Last, comparison between enriched CD11b(+) cells (microglia/macrophages) and enriched GLAST-1(+)/CD11b(-) cells (astrocytes) revealed RSD increased mRNA expression of IL-1β, CCL2, and CXCL2 in microglia/macrophages but not in astrocytes. Collectively, these data indicate that key mediators of leukocyte recruitment were increased in the brain vasculature following RSD in an exposure- and brain region-dependent manner. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

Knockdown of Interleukin-1 Receptor Type-1 on Endothelial Cells Attenuated Stress-Induced Neuroinflammation and Prevented Anxiety-Like Behavior

PubMed Central

Wohleb, Eric S.; Patterson, Jenna M.; Sharma, Vikram; Quan, Ning

2014-01-01

Interleukin-1β (IL-1β) is an inflammatory cytokine that plays a prominent role in stress-induced behavioral changes. In a model of repeated social defeat (RSD), elevated IL-1β expression in the brain was associated with recruitment of primed macrophages that were necessary for development of anxiety-like behavior. Moreover, microglia activation and anxiety-like behavior associated with RSD did not occur in IL-1 receptor type-1 knock-out (IL-1R1KO) mice. Therefore, the objective of this study was to examine the role of IL-1 signaling in RSD-induced macrophage trafficking to the brain and anxiety-like behavior. Initial studies revealed that RSD did not increase circulating myeloid cells in IL-1R1KO mice, resulting in limited macrophage trafficking to the brain. In addition, IL-1R1KO bone marrow-chimera mice showed that IL-1R1 expression was essential for macrophage trafficking into the brain. To differentiate cellular mediators of stress-induced IL-1 signaling, endothelial-specific IL-1R1 knock-down (eIL-1R1kd) mice were used. Both wild-type (WT) and eIL-1R1kd mice had increased circulating monocytes, recruitment of macrophages to the brain, and altered microglia activation after RSD. Nonetheless, RSD-induced expression of IL-1β, TNF-α, and IL-6 mRNA in brain CD11b+ cells was attenuated in eIL-1R1kd mice compared with WT. Moreover, anxiety-like behavior did not develop in eIL-1R1kd mice. Collectively, these findings demonstrated that there was limited RSD-induced priming of myeloid cells in IL-1R1KO mice and disrupted propagation of neuroinflammatory signals in the brain of eIL-1R1kd mice. Furthermore, these data showed that transduction of IL-1 signaling by endothelial cells potentiates stress-induced neuroinflammation and promotes anxiety-like behavior. PMID:24523548

Renal sympathetic denervation improves myocardial apoptosis in rats with isoproterenol-induced heart failure by downregulation of tumor necrosis factor-α and nuclear factor-κB.

PubMed

Yao, Wei; Wang, Neng; Qian, Jin; Bai, Lu; Zheng, Xiaoxin; Hou, Guo; Qiu, Xuan; Yang, Bo

2017-11-01

Chronic congestive heart failure (CHF) is the end outcome of organic heart diseases and one of the major diseases harmful to human health. Renal sympathetic denervation (RSD) is the anatomical basis of transcatheter renal sympathetic nerve ablation within the renal artery. To date, the roles of norepinephrine and angiotensin II (Ang II) in myocardial apoptosis and their underlying mechanisms have not been well explored. The aim of the present study was to verify the hypothesis that RSD is likely to inhibit myocardial apoptosis by inhibiting the release of norepinephrine and Ang II. An isoproterenol-induced CHF rat model was established, and the effects of RSD on myocardial apoptosis were examined using flow cytometry and TUNEL staining. The expression of factors associated with myocardial apoptosis, including p53, tumor necrosis factor-α (TNF-α), nuclear factor-κB (NF-κB), caspase-2 and -3, were measured using quantitative polymerase chain reaction and western blot analysis. The results indicated that the mRNA levels of p53, TNF-α, NF-κB, caspase-2 and -3 were significantly reduced in the myocardial tissues of rats in the CHF+RSD group when compared with the levels in the CHF+sham group (P<0.01 for all). In addition, the protein levels of p53, TNF-α, NF-κB and caspases-2 and -3 were decreased by 42.6, 41.3, 46.7, 30.0 and 35.8%, respectively, in myocardial tissues of rats in the CHF+RSD group in comparison with the CHF+sham group (P<0.01 for all). Furthermore, myocardial apoptosis was improved in rats in the CHF+RSD group compared with that in the CHF+sham group (P<0.01). In conclusion, the present study provides a theoretical basis for application of RSD in the treatment of CHF.

Renal sympathetic denervation improves myocardial apoptosis in rats with isoproterenol-induced heart failure by downregulation of tumor necrosis factor-α and nuclear factor-κB

PubMed Central

Yao, Wei; Wang, Neng; Qian, Jin; Bai, Lu; Zheng, Xiaoxin; Hou, Guo; Qiu, Xuan; Yang, Bo

2017-01-01

Chronic congestive heart failure (CHF) is the end outcome of organic heart diseases and one of the major diseases harmful to human health. Renal sympathetic denervation (RSD) is the anatomical basis of transcatheter renal sympathetic nerve ablation within the renal artery. To date, the roles of norepinephrine and angiotensin II (Ang II) in myocardial apoptosis and their underlying mechanisms have not been well explored. The aim of the present study was to verify the hypothesis that RSD is likely to inhibit myocardial apoptosis by inhibiting the release of norepinephrine and Ang II. An isoproterenol-induced CHF rat model was established, and the effects of RSD on myocardial apoptosis were examined using flow cytometry and TUNEL staining. The expression of factors associated with myocardial apoptosis, including p53, tumor necrosis factor-α (TNF-α), nuclear factor-κB (NF-κB), caspase-2 and −3, were measured using quantitative polymerase chain reaction and western blot analysis. The results indicated that the mRNA levels of p53, TNF-α, NF-κB, caspase-2 and −3 were significantly reduced in the myocardial tissues of rats in the CHF+RSD group when compared with the levels in the CHF+sham group (P<0.01 for all). In addition, the protein levels of p53, TNF-α, NF-κB and caspases-2 and −3 were decreased by 42.6, 41.3, 46.7, 30.0 and 35.8%, respectively, in myocardial tissues of rats in the CHF+RSD group in comparison with the CHF+sham group (P<0.01 for all). Furthermore, myocardial apoptosis was improved in rats in the CHF+RSD group compared with that in the CHF+sham group (P<0.01). In conclusion, the present study provides a theoretical basis for application of RSD in the treatment of CHF. PMID:29104628

Social defeat promotes a reactive endothelium in a brain region-dependent manner with increased expression of key adhesion molecules, selectins and chemokines associated with the recruitment of myeloid cells to the brain

PubMed Central

Sawicki, Caroline M.; McKim, Daniel B.; Wohleb, Eric S.; Jarrett, Brant L.; Reader, Brenda F.; Norden, Diana M.; Godbout, Jonathan P.; Sheridan, John F.

2014-01-01

Repeated social defeat (RSD) in mice causes myeloid cell trafficking to the brain that contributes to the development of prolonged anxiety-like behavior. Myeloid cell recruitment following RSD occurs in regions where neuronal and microglia activation is observed. Thus, we hypothesized that crosstalk between neurons, microglia, and endothelial cells contributes to brain-myeloid cell trafficking via chemokine signaling and vascular adhesion molecules. Here we show that social defeat caused an exposure- and brain region-dependent increase in several key adhesion molecules and chemokines involved in the recruitment of myeloid cells. For example, RSD induced distinct patterns of adhesion molecule expression that may explain brain region-dependent myeloid cell trafficking. VCAM-1 and ICAM-1 mRNA expression were increased in an exposure-dependent manner. Furthermore, RSD-induced VCAM-1 and ICAM-1 protein expression were localized to the vasculature of brain regions implicated in fear and anxiety responses, which spatially corresponded to previously reported patterns of myeloid cell trafficking. Next, mRNA expression of additional adhesion molecules (E- and P-selectin, PECAM-1) and chemokines (CXCL1, CXCL2, CXCL12, CCL2) were determined in the brain. Social defeat induced an exposure-dependent increase in mRNA levels of E-selectin, CXCL1, and CXCL2 that increased with additional days of social defeat. While CXCL12 was unaffected by RSD, CCL2 expression was increased by six days of social defeat. Last, comparison between enriched CD11b+ cells (microglia/macrophages) and enriched GLAST-1+/CD11b− cells (astrocytes) revealed RSD increased mRNA expression of IL-1β, CCL2, and CXCL2 in microglia/macrophages but not in astrocytes. Collectively, these data indicate that key mediators of leukocyte recruitment were increased in the brain vasculature following RSD in an exposure- and brain-region dependent manner. PMID:25445193

ASD-RSD; To Merge or Not to Merge

ERIC Educational Resources Information Center

Sinclair, Dorothy

1971-01-01

This paper clarifies the history of the proposal, and comments on some of the issues involved in the merger of the Reference Services Division (RSD) and the Adult Services Division (ASD) of the American Library Association. (MF)

Sensitivity of geographic information system outputs to errors in remotely sensed data

NASA Technical Reports Server (NTRS)

Ramapriyan, H. K.; Boyd, R. K.; Gunther, F. J.; Lu, Y. C.

1981-01-01

The sensitivity of the outputs of a geographic information system (GIS) to errors in inputs derived from remotely sensed data (RSD) is investigated using a suitability model with per-cell decisions and a gridded geographic data base whose cells are larger than the RSD pixels. The process of preparing RSD as input to a GIS is analyzed, and the errors associated with classification and registration are examined. In the case of the model considered, it is found that the errors caused during classification and registration are partially compensated by the aggregation of pixels. The compensation is quantified by means of an analytical model, a Monte Carlo simulation, and experiments with Landsat data. The results show that error reductions of the order of 50% occur because of aggregation when 25 pixels of RSD are used per cell in the geographic data base.

Characteristics and sources of atmospheric mercury speciation in a coastal city, Xiamen, China.

PubMed

Xu, Lingling; Chen, Jinsheng; Yang, Liming; Niu, Zhenchuan; Tong, Lei; Yin, Liqian; Chen, Yanting

2015-01-01

Semi-continental monitoring of gaseous elemental mercury (GEM), particulate mercury (Hgp), and reactive gaseous mercury (RGM) was conducted in the Institute of Urban Environment, CAS in Xiamen, China from March 2012 to February 2013. The average concentrations and relative standard deviations (RSD) were 3.50 (34.6%) ng m(-3), 174.41 (160.9%) pg m(-3), and 61.05 (113.7%) pg m(-3) for GEM, Hgp, and RGM, respectively. The higher concentrations of GEM and Hgp were observed in spring and winter months, indicating the combustion source, while RGM showed the different seasonal variation with highest concentration in spring and the minimum value in winter. The concentrations of Hg species were generally elevated in nighttime and low in daytime to reflect the diurnal changes in meteorology, especially the mixing condition of the air masses. The high Hg concentrations were observed in SWW-NW sectors due to calm wind while the low levels in NE-SE due to high speed wind, and the amplitude was much larger for Hgp and RGM. Backward trajectories calculation indicated that summer air masses were much more from ocean with lower Hg while the air masses were mainly from inland area in other seasons. Principal component analysis suggested that combustion and road traffic emissions were the dominant anthropogenic mercury sources for the study area, and the temporal distribution of atmospheric mercury was mainly the result of climatological change. Copyright © 2014 Elsevier Ltd. All rights reserved.

Use of gas chromatography-mass spectrometry for the assessment of the contamination caused by small concentrations of nitrophenols in soils and sediments

NASA Astrophysics Data System (ADS)

Cacho, Juan-Ignacio; Campillo, Natalia; Viñas, Pilar; Hernandez-Cordoba, Manuel

2015-04-01

Nitrophenols (NPs) are widely distributed environmental contaminants that can be present in soils and sediments due to the degradation of some pesticides (parathion and fenitrothion) or by accidental spilling in ammunition plants or storage places. This communication reports a rapid and sensitive procedure for the determination of the most common NPs in soils by using gas chromatography coupled to mass spectrometry (GC-MS) as the analytical technique. Ultrasound assisted extraction (UAE) was employed for the extraction of the NPs from the soil samples to an organic solvent. Next, the resulting UAE extracts were submitted to dispersive liquid-liquid microextraction (DLLME) for achieving an effective preconcentration. DLLME is an easy-to-carry out, environmentally friendly separation technique involving minimal amounts of organic solvents. Since the volatility of NPs is low, as a previous stage to the GC-MS measurement the compounds were derivatized using a simple "in-situ" acetylation procedure. The main parameters affecting the UAE stage, as well as the DLLME and derivatization steps, were investigated looking for maximum analytical signals. The optimized procedure provided extraction recoveries in the 72-86% range, with precision values (expressed as relative standard deviation, RSD) ≤ 12%, and detection limits ranging from 1.3 and 3.3 ng g-1, depending on the compound. 20 soil and sediment samples, from military, industrial and agricultural areas were analyzed by the studied procedure in order to check its applicability.

Determination of Os by isotope dilution-inductively coupled plasma-mass spectrometry with the combination of laser ablation to introduce chemically separated geological samples

NASA Astrophysics Data System (ADS)

Sun, Yali; Ren, Minghao; Xia, Xiaoping; Li, Congying; Sun, Weidong

2015-11-01

A method was developed for the determination of trace Os in geological samples by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) with the combination of chemical separation and preconcentration. Samples are digested using aqua regia in Carius tubes, and the Os analyte is converted into volatile OsO4, which is distilled and absorbed with HBr. The HBr solution is concentrated for further Os purification using the microdistillation technique. The purified Os is dissolved in 10 μl of 0.02% sucrose-0.005% H3PO4 solution and then evaporated on pieces of perfluoroalkoxy (PFA) film, resulting in the formation of a tiny object (< 3 × 104 μm2 superficial area). Using LA-ICP-MS measurements, the object can give Os signals at least 100 times higher than those provided by routine solution-ICP-MS while successfully avoiding the memory effect. The procedural blank and detection limit in the developed technique are 3.0 pg and 1.8 pg for Os, respectively when 1 g of samples is taken. Reference materials (RM) are analyzed, and their Os concentrations obtained by isotope dilution are comparable to reference or literature values. Based on the individual RM results, the precision is estimated within the range of 0.6 to 9.4% relative standard deviation (RSD), revealing that this method is applicable to the determination of trace Os in geological samples.

Fast Determination of Ingredients in Solid Pharmaceuticals by Microwave-Enhanced In-Source Decay of Microwave Plasma Torch Mass Spectrometry.

PubMed

Su, Rui; Wang, Xinchen; Hou, Changming; Yang, Meiling; Huang, Keke; Chen, Huanwen

2017-09-01

Rapid qualitative and quantitative analysis of solid samples (e.g., pharmaceutical preparations) by using a small and low-resolution mass spectrometer without MS/MS function is still a challenge in ambient pressure ionization mass spectrometric analysis. Herein, a practically efficient method termed microwave-enhanced in-source decay (MEISD) using microwave plasma torch desorption ionization coupled with time-of-flight mass spectrometry (MPTDI-TOF MS) was developed for fast analysis of pharmaceutical tablets using a miniature TOF mass spectrometer without tandem mass function. The intensity of ISD fragmentation was evaluated under different microwave power values. Several factors, including desorption distance and time that might affect the signal intensity and fragmentation, were systematically investigated. It was observed that both the protonated molecular ions and major fragment ions from the active ingredients in tablets could be found in the full-scan mass spectra in positive ion mode, which were comparable to those obtained by a commercial LTQ-XL ion trap mass spectrometer. The structures of the ingredients could be elucidated in detail using the MEISD method, which promotes our understanding of the desorption/ionization processes in microwave plasma torch (MPT). Quantitative analysis of 10 tablets was achieved by full-scan MPTDI-TOF MS with low limit of detection (LOD, 0.763 mg/g), acceptable relative standard deviation (RSD < 7.33%, n =10), and 10 s for each tablet, showing promising applications in high throughput screening of counterfeit drugs. Graphical Abstract ᅟ.