Microchip-based Integration of Cell Immobilization, Electrophoresis, Post-column Derivatization, and Fluorescence Detection for Monitoring the Release of Dopamine from PC 12 Cells

PubMed Central

Li, Michelle W.; Martin, R. Scott

2008-01-01

In this paper, we describe the fabrication and evaluation of a multilayer microchip device that can be used to quantitatively measure the amount of catecholamines released from PC 12 cells immobilized within the same device. This approach allows immobilized cells to be stimulated on-chip and, through rapid actuation of integrated microvalves, the products released from the cells are repeatedly injected into the electrophoresis portion of the microchip, where the analytes are separated based upon mass and charge and detected through post-column derivatization and fluorescence detection. Following optimization of the post-column derivatization detection scheme (using naphthalene-2,3-dicarboxaldehyde and 2-β-mercaptoethanol), off-chip cell stimulation experiments were performed to demonstrate the ability of this device to detect dopamine from a population of PC 12 cells. The final 3-dimensional device that integrates an immobilized PC 12 cell reactor with the bilayer continuous flow sampling/electrophoresis microchip was used to continuously monitor the on-chip stimulated release of dopamine from PC 12 cells. Similar dopamine release was seen when stimulating on-chip versus off-chip yet the on-chip immobilization studies could be carried out with 500 times fewer cells in a much reduced volume. While this paper is focused on PC 12 cells and neurotransmitter analysis, the final device is a general analytical tool that is amenable to immobilization of a variety of cell lines and analysis of various released analytes by electrophoretic means. PMID:18810283

Low pressure ion chromatography with a low cost paired emitter-detector diode based detector for the determination of alkaline earth metals in water samples.

PubMed

Barron, Leon; Nesterenko, Pavel N; Diamond, Dermot; O'Toole, Martina; Lau, King Tong; Paull, Brett

2006-09-01

The use of a low pressure ion chromatograph based upon short (25 mm x 4.6 mm) surfactant coated monolithic columns and a low cost paired emitter-detector diode (PEDD) based detector, for the determination of alkaline earth metals in aqueous matrices is presented. The system was applied to the separation of magnesium, calcium, strontium and barium in less than 7min using a 0.15M KCl mobile phase at pH 3, with post-column reaction detection at 570 nm using o-cresolphthalein complexone. A comparison of the performance of the PEDD detector with a standard laboratory absorbance detector is shown, with limits of detection for magnesium and calcium using the low cost PEDD detector equal to 0.16 and 0.23 mg L(-1), respectively. Finally, the developed system was used for the determination of calcium and magnesium in a commercial spring water sample.

Nano-LC/MALDI-MS using a column-integrated spotting probe for analysis of complex biomolecule samples.

PubMed

Hioki, Yusaku; Tanimura, Ritsuko; Iwamoto, Shinichi; Tanaka, Koichi

2014-03-04

Nanoflow liquid chromatography (nano-LC) is an essential technique for highly sensitive analysis of complex biological samples, and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is advantageous for rapid identification of proteins and in-depth analysis of post-translational modifications (PTMs). A combination of nano-LC and MALDI-MS (nano-LC/MALDI-MS) is useful for highly sensitive and detailed analysis in life sciences. However, the existing system does not fully utilize the advantages of each technique, especially in the interface of eluate transfer from nano-LC to a MALDI plate. To effectively combine nano-LC with MALDI-MS, we integrated a nano-LC column and a deposition probe for the first time (column probe) and incorporated it into a nano-LC/MALDI-MS system. Spotting nanoliter eluate droplets directly from the column onto the MALDI plate prevents postcolumn diffusion and preserves the chromatographic resolution. A DHB prespotted plate was prepared to suit the fabricated column probe to concentrate the droplets of nano-LC eluate. The performance of the advanced nano-LC/MALDI-MS system was substantiated by analyzing protein digests. When the system was coupled with multidimensional liquid chromatography (MDLC), trace amounts of glycopeptides that spiked into complex samples were successfully detected. Thus, a nano-LC/MALDI-MS direct-spotting system that eliminates postcolumn diffusion was constructed, and the efficacy of the system was demonstrated through highly sensitive analysis of the protein digests or spiked glycopeptides.

Measurement of bromate in bread by liquid chromatography with post-column flow reactor detection.

PubMed

Himata, K; Noda, M; Ando, S; Yamada, Y

2000-01-01

This method is suitable for the determination of bromate residues in a variety of baked goods. The peer-verified method trial was performed on white bread, multigrain bread, and coffee cake spiked with known levels of potassium bromate. The analytical portion is extracted with deionized water to remove bromate from the bulk of the baked product. The aqueous extract is carried through a series of steps to remove co-extractives that would interfere with the liquid chromatography (LC) in the determinative step or hasten the deterioration of the LC column. The extract is filtered before passing it through a reversed-phase solid-phase extraction (SPE) column and a cation-exchange column in the silver form to remove lipids and chloride, respectively. Ultrafiltration is then used to remove proteins with molecular weights of >30,000 daltons. Finally, a cation-exchange column in the sodium form is used to remove silver ions from the extract. The determinative step uses LC with a reversed-phase column and an ion-pairing agent in the mobile phase. Detection is based on the post-column reaction of bromate with o-dianisidine to form an oxidation product that is quantitated spectrophotometrically at 450 nm. Overall agreement between the submitting and peer laboratories was quite good. For bromate levels of 10-52 ppb, overall mean recoveries were 76.9 and 78.8% for the submitting and peer laboratories, respectively. The standard deviations were higher for the results of the peer laboratory, probably because of the generally higher level of baseline noise present in the chromatograms. The results demonstrate that the method provides adequate accuracy with low-fat as well as high-fat foods. Bromate at levels as low as 5 ppb (ng/g) can be detected with the method.

Application of response surface methodology (RSM) to the optimization of a post-column luminol chemiluminescence analysis of silyl peroxides.

PubMed

Baj, Stefan; Słupska, Roksana; Krawczyk, Tomasz

2013-01-15

The possibility of the utilization of chemiluminescence post-column luminol oxidation (CL) in a HPLC system for silyl peroxides analysis has been investigated. The conditions of HPLC separation for 12 silyl peroxides, representing bissilyl and alkyl-silyl peroxides, as well as their potential impurities, were established. Optimal chemiluminescent post-column reaction conditions were found using central composite design (CCD) and response surface methodology (RSM). The interaction effects of four of the most important operating variables - the concentrations of luminol, hemin, sodium hydroxide and the post-column solution flow rate - on the light intensity were evaluated. The optimized conditions for analysis were the same for bissilyl and alkyl-silyl peroxides for the base concentration (0.03 M), the luminol concentration (0.4 g L(-1)) and the hemin concentration (0.3 g L(-1)). The only differences occurred in a reagent flow rate (for bissilyl peroxide -0.3 mL min(-1) and for alkyl-silyl peroxides -0.9 mL min(-1)). Under optimal conditions, the detection limits were in the 0.07-0.16 nM range for bissilyl, and 0.53-1.01 for alkyl-silyl peroxides. The calibration curves were linear in the 0.25-3 nM range for bissilyl and the 2.5-25 range for alkyl-silyl peroxides. Intra-day and inter-day precision was lower than 5.5% for each tested concentration level. A mechanism of luminol oxidation by silyl peroxides involving a hydrolysis step with the formation of hydrogen peroxide or hydroperoxide was proposed. Copyright © 2012 Elsevier B.V. All rights reserved.

Simultaneous multi-mycotoxin determination in nutmeg by ultrasound-assisted solid-liquid extraction and immunoaffinity column clean-up coupled with liquid chromatography and on-line post-column photochemical derivatization-fluorescence detection.

PubMed

Kong, Wei-Jun; Liu, Shu-Yu; Qiu, Feng; Xiao, Xiao-He; Yang, Mei-Hua

2013-05-07

A simple and sensitive analytical method based on ultrasound-assisted solid-liquid extraction and immunoaffinity column clean-up coupled with high performance liquid chromatography and on-line post-column photochemical derivatization-fluorescence detection (USLE-IAC-HPLC-PCD-FLD) has been developed for simultaneous multi-mycotoxin determination of aflatoxins B1, B2, G1, G2 (AFB1, AFB2, AFG1, AFG2) and ochratoxin A (OTA) in 13 edible and medicinal nutmeg samples marketed in China. AFs and OTA were extracted from nutmeg samples by ultrasonication using a methanol : water (80 : 20, v/v) solution, followed by an IAC clean-up step. Different USL extraction conditions, pre-processing ways for nutmeg sample and clean-up columns for mycotoxins, as well as HPLC-PCD-FLD parameters (mobile phase, column temperature, elution procedure, excitation and emission wavelengths) were optimized. This method, which was appraised for analyzing nutmeg samples, showed satisfactory results with reference to limits of detection (LODs) (from 0.02 to 0.25 μg kg(-1)), limits of quantification (LOQs) (from 0.06 to 0.8 μg kg(-1)), linear ranges (up to 30 ng mL(-1) for AFB1, AFG1 and OTA and 9 ng mL(-1) for AFB2 and AFG2), intra- and inter-day variability (all <2%) and average recoveries (from 79.6 to 90.8% for AFs and from 93.6 to 97.3% for OTA, respectively). The results of the application of developed method in nutmeg samples have elucidated that four samples were detected with contamination of AFs and one with OTA. AFB1 was the most frequently found mycotoxin in 30.8% of nutmeg samples at contamination levels of 0.73-16.31 μg kg(-1). At least two different mycotoxins were co-occurred in three samples, and three AFs were simultaneously detected in one sample.

Gas chromatography fractionation platform featuring parallel flame-ionization detection and continuous high-resolution analyte collection in 384-well plates.

PubMed

Jonker, Willem; Clarijs, Bas; de Witte, Susannah L; van Velzen, Martin; de Koning, Sjaak; Schaap, Jaap; Somsen, Govert W; Kool, Jeroen

2016-09-02

Gas chromatography (GC) is a superior separation technique for many compounds. However, fractionation of a GC eluate for analyte isolation and/or post-column off-line analysis is not straightforward, and existing platforms are limited in the number of fractions that can be collected. Moreover, aerosol formation may cause serious analyte losses. Previously, our group has developed a platform that resolved these limitations of GC fractionation by post-column infusion of a trap solvent prior to continuous small-volume fraction collection in a 96-wells plate (Pieke et al., 2013 [17]). Still, this GC fractionation set-up lacked a chemical detector for the on-line recording of chromatograms, and the introduction of trap solvent resulted in extensive peak broadening for late-eluting compounds. This paper reports advancements to the fractionation platform allowing flame ionization detection (FID) parallel to high-resolution collection of a full GC chromatograms in up to 384 nanofractions of 7s each. To this end, a post-column split was incorporated which directs part of the eluate towards FID. Furthermore, a solvent heating device was developed for stable delivery of preheated/vaporized trap solvent, which significantly reduced band broadening by post-column infusion. In order to achieve optimal analyte trapping, several solvents were tested at different flow rates. The repeatability of the optimized GC fraction collection process was assessed demonstrating the possibility of up-concentration of isolated analytes by repetitive analyses of the same sample. The feasibility of the improved GC fractionation platform for bioactivity screening of toxic compounds was studied by the analysis of a mixture of test pesticides, which after fractionation were subjected to a post-column acetylcholinesterase (AChE) assay. Fractions showing AChE inhibition could be unambiguously correlated with peaks from the parallel-recorded FID chromatogram. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of ion chromatographic methods based on conductivity detection, post-column-reaction and on-line-coupling IC-ICP-MS for the determination of bromate.

PubMed

Schminke, G; Seubert, A

2000-02-01

An established method for the determination of the disinfection by-product bromate is ion chromatography (IC). This paper presents a comparison of three IC methods based on either conductivity detection (IC-CD), a post-column-reaction (IC-PCR-VIS) or the on-line-coupling with inductively coupled plasma mass spectrometry (IC-ICP-MS). Main characteristics of the methods such as method detection limits (MDL), time of analysis and sample pretreatment are compared and applicability for routine analysis is critically discussed. The most sensitive and rugged method is IC-ICP-MS, followed by IC-PCR-VIS. The photometric detection is subject to a minor interference in real world samples, presumably caused by carbonate. The lowest sensitivity is shown by the IC-CD method as slowest method compared, which, in addition, requires a sample pretreatment. The highest amount of information is delivered by IC-PCR-VIS, which allows the simultaneous determination of the seven standard anions and bromate.

Aqueous Reversed-Phase HPLC/FT-IR Using Diffuse Reflectance Detections

NASA Astrophysics Data System (ADS)

Kalasinsky, Victor F.; Pai, T. H.; Kenton, R. C.; Kalasinsky, Kathryn S.

1989-12-01

Solvent-elimination HPLC/FT-IR has become a viable combination of two important techniques, and we have been developing a system which is adaptable to both normal and reversed-phase liquid chromatography. The interface involves the deposition of HPLC eluites onto a KCI-laden train with subsequent analysis via diffuse reflectance spectroscopy, and with minor modifications, the system can be used with microbore and analytical columns. With aqueous solvents, the water is converted to methanol and acetone in a post-column reaction with 2,2-dimethoxypropane before the eluites are deposited. A number of different samples have been used to demonstrate the interface and its flexibility. Steroids, analgesics, and other pharmaceutical preparations have been separated with reverse-phase solvents and identified by their infrared spectra. For some of the compounds studied, different infrared spectra of a given compound have been found to exhibit intensity variations, which arise from different crystalline states. The differences can be concentration dependent and may be useful in obtaining semi-quantitative information from the infrared spectra. Applications involving both gradient elution and isocratic separations have been successful. The former provides the same advantages for HPLC/FT-IR as one finds in conventional HPLC. More recent work has been applied to the use of buffers such as those frequently used in bioanalytical separations. In trying to simplify the post-column reaction with water, we have immobilized dehydration reagents onto silica particles and packed these materials into a column which is inserted in-line after the analytical column. Of the reagents utilized to date, 3,3-dimethoxypropyltrimethoxysilane has been found to perform most efficiently. It has advantages over the simpler reagents because it can be regenerated in the reaction column. Results and the efficiency of the dehydration process and its relation to the type of reagent and its coverage will be discussed.

High sensitivity detection of bisphenol A using liposome chromatography.

PubMed

Liu, Xue-Ying; Nakamura, Chikashi; Tanimoto, Itsuro; Miyake, Shiro; Nakamura, Noriyuki; Hirano, Takashi; Miyake, Jun

2006-09-18

An antibody column in tandem with a fluorescent dye entrapped liposome column was developed for highly sensitive detection of an endocrine disruptor, bisphenol A (BPA). Anti-BPA antibody was immobilized in a protein G column with orientation control. A derivative of BPA was conjugated to phospholipase A2 (PLA2). BPA sample solutions mixed with the BPA-PLA2 conjugates were injected on to the anti-BPA antibody column and competitive binding occurred in the antibody column. The amount of the free conjugate was proportional to the concentration of the BPA sample. The eluted conjugates were injected on to the second column gel on which calcein-entrapped liposomes were immobilized and the PLA2-catalyzed hydrolysis of liposomal phospholipids causing fluorescent dye leakage as a signal amplification. In this system, the mixture of BPA and BPA-PLA2 conjugate were incubated for 60 min in the anti-BPA column, and then the collected solution was applied to the liposome column. The BPA detection range of 0.02-140 ng mL(-1) was wider than 0.03-6.6 ng mL(-1) obtained by the method of competitive ELISA using the same antibody. Moreover, this system could be adapted to an HPLC system resulting in almost the same detection limit in online detection. The method could be applied to environmental samples, river water and soil extracts. The BPA concentration of 0.1 ng mL(-1) and 10 ng g(-1) was detectable in water and soil extract, respectively.

Paired emitter-detector diode detection with dual wavelength monitoring for enhanced sensitivity to transition metals in ion chromatography with post-column reaction.

PubMed

O' Toole, Martina; Barron, Leon; Shepherd, Roderick; Paull, Brett; Nesterenko, Pavel; Diamond, Dermot

2009-01-01

The combination of post-column derivatisation and visible detection are regularly employed in ion chromatography (IC) to detect poorly absorbing species. Although this mode is often highly sensitive, one disadvantage is the increase in repeating baseline artifacts associated with out-of-sync pumping systems. The work presented here will demonstrate the use of a second generation design paired emitter-detector diode (PEDD-II) detection mode offering enhanced sensitivity to transition metals in IC by markedly reducing this problem and also by improving signal noise. First generation designs demonstrated the use of a single integrated PEDD detector cell as a simple, small (15 x 5 mm), highly sensitive, low cost photometric detector for the detection of metals in IC. The basic principle of this detection mode lies in the employment of two linear light emitting diodes (LEDs), one operating in normal mode as a light source and the other in reverse bias serving as a light detector. The second generation PEDD-II design showed increased sensitivity for Mn(II)- and Co(II)-2-(pyridylazo)resorcinol (PAR) complexes as a result of two simultaneously acquiring detection cells--one analytical PEDD cell and one reference PEDD cell. Therefore, the PEDD-II employs two wavelengths whereby one monitors the analyte reaction product and the second monitors a wavelength close to the isosbestic point. The optimum LED wavelength to be used for the analytical cell was investigated to maximise peak response. The fabrication process for both the analytical and reference PEDD cells was validated by determining the reproducibility of detectors within a batch. The reproducibility and sensitivity of the PEDD-II detector was then investigated using signals obtained from both intra- and inter-day chromatograms.

29 CFR 1926.751 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... brakes, rolls, or other methods to shape steel into desired cross sections at room temperature. Column means a load-carrying vertical member that is part of the primary skeletal framing system. Columns do..., such as a wall or column and work with both hands free while leaning. Post means a structural member...

29 CFR 1926.751 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... brakes, rolls, or other methods to shape steel into desired cross sections at room temperature. Column means a load-carrying vertical member that is part of the primary skeletal framing system. Columns do..., such as a wall or column and work with both hands free while leaning. Post means a structural member...

29 CFR 1926.751 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... brakes, rolls, or other methods to shape steel into desired cross sections at room temperature. Column means a load-carrying vertical member that is part of the primary skeletal framing system. Columns do..., such as a wall or column and work with both hands free while leaning. Post means a structural member...

Signal Enhancement in HPLC/Micro-Coil NMR Using Automated Column Trapping

PubMed Central

Djukovic, Danijel; Liu, Shuhui; Henry, Ian; Tobias, Brian; Raftery, Daniel

2008-01-01

A new HPLC-NMR system is described that performs analytical separation, pre-concentration, and NMR spectroscopy in rapid succession. The central component of our method is the online pre-concentration sequence that improves the match between post-column analyte peak volume and the micro-coil NMR detection volume. Separated samples are collected on to a C18 guard column with a mobile phase composed of 90% D2O/10% acetonitrile-D3, and back-flashed to the NMR micro-coil probe with 90% acetonitrile-D3/10% D2O. In order to assess the performance of our unit, we separated a standard mixture of 1 mM ibuprofen, naproxen, and phenylbutazone using a commercially available C18 analytical column. The S/N measurements from the NMR acquisitions indicated that we achieved signal enhancement factors up to 10.4 (±1.2)-fold. Furthermore, we observed that pre-concentration factors increased as the injected amount of analyte decreased. The highest concentration enrichment of 14.7 (±2.2)-fold was attained injecting 100 μL solution of 0.2 mM (~4 μg) ibuprofen. PMID:17037915

Ten-year monitoring of high-rise building columns using long-gauge fiber optic sensors

NASA Astrophysics Data System (ADS)

Glisic, B.; Inaudi, D.; Lau, J. M.; Fong, C. C.

2013-05-01

A large-scale lifetime building monitoring program was implemented in Singapore in 2001. The monitoring aims of this unique program were to increase safety, verify performance, control quality, increase knowledge, optimize maintenance costs, and evaluate the condition of the structures after a hazardous event. The first instrumented building, which has now been monitored for more than ten years, is presented in this paper. The long-gauge fiber optic strain sensors were embedded in fresh concrete of ground-level columns, thus the monitoring started at the birth of both the construction material and the structure. Measurement sessions were performed during construction, upon completion of each new story and the roof, and after the construction, i.e., in-service. Based on results it was possible to follow and evaluate long-term behavior of the building through every stage of its life. The results of monitoring were analyzed at a local (column) and global (building) level. Over-dimensioning of one column was identified. Differential settlement of foundations was detected, localized, and its magnitude estimated. Post-tremor analysis was performed. Real long-term behavior of concrete columns was assessed. Finally, the long-term performance of the monitoring system was evaluated. The researched monitoring method, monitoring system, rich results gathered over approximately ten years, data analysis algorithms, and the conclusions on the structural behavior and health condition of the building based on monitoring are presented in this paper.

High-performance liquid chromatography post-column derivatization with fluorescence detection to study the influence of ambroxol on dipalmitoylphosphatidylcholine levels in rabbit eustachian tube washings.

PubMed

Kitsos, M; Gandini, C; Massolini, G; De Lorenzi, E; Caccialanza, G

1991-08-16

In this work an appropriate high-performance liquid chromatography method was set up to guarantee specificity, sensitivity, precision and accuracy in analyzing dipalmitoylphosphatidylcholine (DPPC) in rabbit eustachian tube washings, as well as to determine its varying levels after administration of ambroxol chloride. The procedure is based on a post-column derivatization with fluorescence detection using 1,6-diphenyl-1,3,5-hexatriene which exhibits increased fluorescence in a lipid environment. DPPC was chromatographed on a Hypersil C18. The mobile phase for the isocratic elution consisted of 40 mmol/l choline chloride in methanol-tetrahydrofuran (97:3). Ambroxol was given to a group of New Zealand white rabbits at a dose of 30 mg/kg. A second group receiving vehicle only acted as controls.

Demonstration of motionless Knudsen pump based micro-gas chromatography featuring micro-fabricated columns and on-column detectors.

PubMed

Liu, Jing; Gupta, Naveen K; Wise, Kensall D; Gianchandani, Yogesh B; Fan, Xudong

2011-10-21

This paper reports the investigation of a micro-gas chromatography (μGC) system that utilizes an array of miniaturized motionless Knudsen pumps (KPs) as well as microfabricated separation columns and optical detectors. A prototype system was built to achieve a flow rate of 1 mL min(-1) and 0.26 mL min(-1) for helium and dry air, respectively, when they were used as carrier gas. This system was then employed to evaluate GC performance compromises and demonstrate the ability to separate and detect gas mixtures containing analytes of different volatilities and polarities. Furthermore, the use of pressure programming of the KP array was demonstrated to significantly shorten the analysis time while maintaining a high detection resolution. Using this method, we obtained a high resolution detection of 5 alkanes of different volatilities within 5 min. Finally, we successfully detected gas mixtures of various polarities using a tandem-column μGC configuration by installing two on-column optical detectors to obtain complementary chromatograms.

Numerical simulation of CFRP-repaired reinforced concrete columns.

DOT National Transportation Integrated Search

2014-07-01

The overarching goal of this study was to investigate the influence of repair to individual reinforced concrete bridge columns on the : post-repair seismic performance of the bridge system. A method was developed to rapidly repair an earthquake-damag...

Differential coulometric oxidation following post column-switching high pressure liquid chromatography for fluorescence measurement of unmetabolized folic acid in human plasma.

PubMed

Bailey, Steven W; Ayling, June E

2013-11-08

Although many countries have fortified their grain supplies with folic acid (FA) to decrease the incidence of neural tube defects, others have not due to concerns that this synthetic folate might have some adverse effects. Persistent unmetabolized FA has been found even in plasma from fasted subjects. To facilitate measurement of low levels of folic acid in human plasma, post-column coulometric oxidative cleavage was used to convert poorly fluorescent FA into a highly fluorescent compound determined to be 6-formyl-pterin. To minimize sample work-up and maximize recovery, column-switching HPLC transferred a window of eluate containing the FA from the first column (C8) onto a second column (phenyl-hexyl). The pH of two mobile phases were adjusted to be above and then below a pK of the FA α-carboxyl group, thus promoting separation from compounds coeluting from the C8-column. This permitted sample preparation using only a simple high recovery protein precipitation. Definitive identification of FA in human plasma was accomplished by duplicate injections of sample with the electrochemical voltage set above and below its half-potential. The LOD (S/N=3) was 0.10 nM. The intra- and inter-assay CV's were 2.3% and 5%, respectively. Comparison of these results with those obtained by HPLC/MS/MS with stable isotope internal standard showed a slope of 1.00 ± 0.019. This simple, sensitive, and repeatable assay facilitates a more thorough investigation of the response of various human populations to folic acid intake. Post-column differential coulometric electrochemistry can expand the variety of compounds amenable to fluorescence detection. Copyright © 2013 Elsevier B.V. All rights reserved.

Device to improve detection in electro-chromatography

DOEpatents

Garguilo, Michael G.; Paul, Phillip H.; Rakestraw, David J.

2000-01-01

Apparatus and method for improving the resolution of non-pressure driven capillary chromatographic systems, and particularly for capillary electrochromatography (CEC) systems. By reducing the cross-sectional area of a packed capillary column by means of a second open capillary contiguous with the outlet end of a packed capillary column, where the packed capillary column has a cross sectional area of between about 2 and 5 times that of the open capillary column, the phenomenon of band broadening in the transition region between the open capillary and the packed capillary column, where the individual components of the mixture are analyzed, can be eliminated, thereby providing for a significant improvement in resolution and more accurate detection and analysis.

Device to improve detection in electro-chromatography

DOEpatents

Garguilo, Michael G.; Paul, Phillip H.; Rakestraw, David J.

2002-01-01

Apparatus and method for improving the resolution of non-pressure driven capillary chromatographic systems, and particularly for capillary electrochromatography (CEC) systems. By reducing the cross-sectional area of a packed capillary column by means of a second open capillary contiguous with the outlet end of a packed capillary column, where the packed capillary column has a cross sectional area of between about 2 and 5 times that of the open capillary column, the phenomenon of band broadening in the transition region between the open capillary and the packed capillary column, where the individual components of the mixture are analyzed, can be eliminated, thereby providing for a significant improvement in resolution and more accurate detection and analysis.

Simple gas chromatographic system for analysis of microbial respiratory gases

NASA Technical Reports Server (NTRS)

Carle, G. C.

1972-01-01

Dual column ambient temperature system, consisting of pair of capillary columns, microbead thermistor detector and micro gas-sampling valve, is used in remote life-detection equipment for space experiments. Performance outweighs advantage gained by utilizing single-column systems to reduce weight, conserve carrier gas and operate at lower power levels.

Post-column reaction for simultaneous analysis of chromatic and leuco forms of malachite green and crystal violet by high-performance liquid chromatography with photometric detection

USGS Publications Warehouse

Allen, J.L.; Meinertz, J.R.

1991-01-01

The chromatic and leuco forms of malachite green and crystal violet were readily separated and detected by a sensitive and selective high-performance liquid chromatographic procedure. The chromatic and leuco forms of the dyes were separated within 11 min on a C18 column with a mobile phase of 0.05 M sodium acetate and 0.05 M acetic acid in water (19%) and methanol (81%). A reaction chamber, containing 10% PbO2 in Celite 545, was placed between the column and the spectrophotometric detector to oxidize the leuco forms of the dyes to their chromatic forms. Chromatic and leuco malachite green were quantified by their absorbance at 618 nm; and chromatic and leuco Crystal Violet by their absorbance at 588 nm. Detection limits for chromatic and leuco forms of both dyes ranged from 0.12 to 0.28 ng. A linear range of 1 to 100 ng was established for both forms of the dyes.

Sensitivity improvement in hydrophilic interaction chromatography negative mode electrospray ionization mass spectrometry using 2-(2-methoxyethoxy)ethanol as a post-column modifier for non-targeted metabolomics.

PubMed

Koch, Wendelin; Forcisi, Sara; Lehmann, Rainer; Schmitt-Kopplin, Philippe

2014-09-26

The application of ammonia acetate buffered liquid chromatography (LC) eluents is known to concomitantly lead to ion suppression when electrospray ionization mass spectrometry (ESI-MS) detection is used. In negative ESI mode, post column infusion of 2-(2-methoxyethoxy)ethanol (2-MEE) was shown in the literature to help to compensate this adverse effect occurring in reversed phase liquid chromatography mass spectrometry (RP-LC-MS) analyses. Here a setup of direct infusion and hydrophilic interaction chromatography (HILIC) post-column infusion experiments was established in order to investigate systematically the beneficial effects of 2-MEE. We demonstrate that, 2-MEE can help to improve ESI-MS sensitivity in HILIC too and reveal analyte structure specific behaviors. Our study indicates that 2-MEE especially improves ESI response for small and polar molecules. The ESI response of stable isotope labeled amino acids spiked into biological matrices increases up to 50-fold (i.e. D5-l-glutamic acid) when post column infusion of 2-MEE is applied. A non-targeted analysis of a pooled urine sample via HILIC-ESI-QTOF-MS supports this hypothesis. In direct infusion, the combined application of an ammonia acetate buffered solution together with 2-MEE results in an improved ESI response compared to a non-buffered solution. We observed up to 60-fold increased ESI response of l-lysine. We propose this effect is putatively caused by the formation of smaller ESI droplets and stripping of positive charge from ESI droplets due to evaporation of acetic acid anions. In summary, post-column infusion of 2-MEE especially enhances ESI response of small and polar molecules. Therefore it can be regarded as a valuable add-on in targeted or non-targeted metabolomic HILIC-MS studies since this method sets a focus on this molecule category. Copyright © 2014 Elsevier B.V. All rights reserved.

Optimization of post-column reactor radius in capillary high performance liquid chromatography Effect of chromatographic column diameter and particle diameter

PubMed Central

Xu, Hongjuan; Weber, Stephen G.

2006-01-01

A post-column reactor consisting of a simple open tube (Capillary Taylor Reactor) affects the performance of a capillary LC in two ways: stealing pressure from the column and adding band spreading. The former is a problem for very small radius reactors, while the latter shows itself for large reactor diameters. We derived an equation that defines the observed number of theoretical plates (Nobs) taking into account the two effects stated above. Making some assumptions and asserting certain conditions led to a final equation with a limited number of variables, namely chromatographic column radius, reactor radius and chromatographic particle diameter. The assumptions and conditions are that the van Deemter equation applies, the mass transfer limitation is for intraparticle diffusion in spherical particles, the velocity is at the optimum, the analyte’s retention factor, k′, is zero, the post-column reactor is only long enough to allow complete mixing of reagents and analytes and the maximum operating pressure of the pumping system is used. Optimal ranges of the reactor radius (ar) are obtained by comparing the number of observed theoretical plates (and theoretical plates per time) with and without a reactor. Results show that the acceptable reactor radii depend on column diameter, particle diameter, and maximum available pressure. Optimal ranges of ar become narrower as column diameter increases, particle diameter decreases or the maximum pressure is decreased. When the available pressure is 4000 psi, a Capillary Taylor Reactor with 12 μm radius is suitable for all columns smaller than 150 μm (radius) packed with 2–5 μm particles. For 1 μm packing particles, only columns smaller than 42.5 μm (radius) can be used and the reactor radius needs to be 5 μm. PMID:16494886

[Determination of fumonisins B1 and B2 in corn by high performance liquid chromatography with post-column derivatization method].

PubMed

Zhang, Xiaoxu; Xiao, Zhiyong; Zhang, Hongyan; Yang, Lili; Ma, Liyan

2012-08-01

A high performance liquid chromatography-fluorescence detection with post-column derivatization method was developed to detect fumonisin B1 (FB1) and fumonisin B2 (FB2) in corn. Several factors, such as the pH of derivatization buffer, concentration and flow rate of derivatization reagents, excitation wavelength, emission wavelength, which affected the detection of fumonisins were optimized. The separation was performed on a ZORBAX SB C18 column operated at 40 degrees C with the gradient elution by two mobile phases of 0.1 mol/L sodium dihydrogen phosphate solution (pH 3.3) and methanol at a flow rate of 0.8 mL/min. The derivatization was performed at ambient temperature. The o-phthalaldehyde (OPA) flow rate was 0.4 mL/min. The results showed that the optimum conditions were pH 10.5 of the derivatization reagent, OPA concentration at 2 g/L, and excitation wavelength of 335 nm, emission wavelength of 440 nm. The linear plots of FB1 and FB2 were obtained between 0.2 to 20 mg/L, with the correlation coefficients above 0.999 for both FB1 and FB2. The limits of detection of fumonisins B1 and B2 were 0.02 mg/kg. The mean recoveries at the three spiked levels of 0.1 - 4.0 mg/kg were 82.5% - 89.8%. This method is accurate, simple, rapid and suitable for the determination of fumonisins B1 and B2 in corn.

Detection biomarkers of lung cancer using mini-GC-PID system integrated with micro GC column and micro pre-concentrator

PubMed Central

2014-01-01

The survival rate of lung cancer can be significantly improved by monitoring biomarkers in exhaled air that indicate diseases in early stage, so it is very important to develop micro analytical systems which can offer a fast, on-site, real-time detecting biomarkers in exhaled air. In this paper, a mini-gas chromatography (GC)-photo-ionization detector (PID) system integrated with a micro GC column and a micro pre-concentrator was developed for forming an inexpensive, fast, and non-invasive diagnostic tool for lung cancer. This system has very strong concentrate ability owing to its integrated micro pre-concentrator, which make the detection of trace components in exhaled air very easy. In addition, the integrated micro GC column can separate complex mixtures, which overcome low resolution and poor anti-interference ability of other instruments. The results indicated that the mini-GC-PID system can effectively separate and detect the biomarkers at parts-per-billion (ppb) level. PMID:25339856

Development of a microcapillary column for detecting targeted messenger RNA molecules.

PubMed

Ohnishi, Michihiro

2006-03-24

A capillary column in a rapid-flow system has been developed for detecting targeted messenger RNA (mRNA) molecules. The column has a structure made of two beds-one bed of porous microbeads and one bed of microbeads with a polythymidine base sequence. The targeted eukaryotic mRNA molecules are detected by two-step hybridization (sandwich hybridization) composed of polyadenosine selection of mRNA molecules and formation of a probe-target (targeted mRNA) hybrid. The sandwich hybridization, which is accomplished within 1 h, was tested using synthetic polydeoxynucleotides. Ten picomoles of the targeted polydeoxynucleotide were detected.

Determination of carbon isotope ratios for honey samples by means of a liquid chromatography/isotope ratio mass spectrometry system coupled with a post-column pump.

PubMed

Kawashima, Hiroto; Suto, Momoka; Suto, Nana

2018-05-20

Liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) has been used to authenticate and trace products such as honey, wine, and lemon juice, and compounds such as caffeine and pesticides. However, LC/IRMS has several disadvantages, including the high cost of the CO 2 membrane and blocking by solidified sodium persulfate. Here, we developed an improved system for determining carbon isotope ratios by LC/IRMS. The main improvement was the use of a post-column pump. Using the improved system, we determined δ 13 C values for glucose with high accuracy and precision (0.1‰ and 0.1‰, respectively; n = 3). The glucose, fructose, disaccharide, trisaccharide, and organic acid constituents of the honey samples were analyzed by LC/IRMS. The δ 13 C values for glucose, fructose, disaccharides, trisaccharides, and organic acids ranged from -27.0 to -24.2‰, -26.8 to -24.0‰, -28.8 to -24.0‰, -27.8 to -22.8‰, and -30.6 to -27.4‰, respectively. The analysis time was 1/3-1/2 the times required for analysis by previously reported methods. The column flow rate could be arbitrarily adjusted with the post-column pump. We applied the improved method to 26 commercial honey samples. Our results can be expected to be useful for other researchers who use LC/IRMS. This article is protected by copyright. All rights reserved.

The effect of dilution and the use of a post-extraction nucleic acid purification column on the accuracy, precision, and inhibition of environmental DNA samples

USGS Publications Warehouse

Mckee, Anna M.; Spear, Stephen F.; Pierson, Todd W.

2015-01-01

Isolation of environmental DNA (eDNA) is an increasingly common method for detecting presence and assessing relative abundance of rare or elusive species in aquatic systems via the isolation of DNA from environmental samples and the amplification of species-specific sequences using quantitative PCR (qPCR). Co-extracted substances that inhibit qPCR can lead to inaccurate results and subsequent misinterpretation about a species’ status in the tested system. We tested three treatments (5-fold and 10-fold dilutions, and spin-column purification) for reducing qPCR inhibition from 21 partially and fully inhibited eDNA samples collected from coastal plain wetlands and mountain headwater streams in the southeastern USA. All treatments reduced the concentration of DNA in the samples. However, column purified samples retained the greatest sensitivity. For stream samples, all three treatments effectively reduced qPCR inhibition. However, for wetland samples, the 5-fold dilution was less effective than other treatments. Quantitative PCR results for column purified samples were more precise than the 5-fold and 10-fold dilutions by 2.2× and 3.7×, respectively. Column purified samples consistently underestimated qPCR-based DNA concentrations by approximately 25%, whereas the directional bias in qPCR-based DNA concentration estimates differed between stream and wetland samples for both dilution treatments. While the directional bias of qPCR-based DNA concentration estimates differed among treatments and locations, the magnitude of inaccuracy did not. Our results suggest that 10-fold dilution and column purification effectively reduce qPCR inhibition in mountain headwater stream and coastal plain wetland eDNA samples, and if applied to all samples in a study, column purification may provide the most accurate relative qPCR-based DNA concentrations estimates while retaining the greatest assay sensitivity.

High-performance liquid chromatography study of gatifloxacin and sparfloxacin using erythrosine as post-column resonance Rayleigh scattering reagent and mechanism study.

PubMed

Pan, Ziyu; Peng, Jingdong; Zang, Xu; Peng, Huanjun; Xiao, Huan; Bu, Lingli; Chen, Fang; He, Yan; Chen, Yu; Wang, Xiang; Li, Shiyu; Chen, Yi

2018-03-01

Herein, a highly selective high-performance liquid chromatography (HPLC) coupled with resonance Rayleigh scattering (RRS) method was developed to detect gatifloxacin (GFLX) and sparfloxacin (SPLX). GFLX and SPLX were first separated by HPLC, then, in pH 4.4 Britton-Robinson (BR) buffer medium, protonic quaternary ammonia cation of GFLX and SPLX reacted with erythrosine (ERY) to form 1:1 ion-association complexes, which resulted in a significant enhancement of RRS signal. The experimental conditions of HPLC and post-column RRS have been investigated, including detection wavelength, flow rate, pH, reacting tube length and reaction temperature. Reaction mechanism were studied in detail by calculating the distribution fraction. The maximum RRS signals for GFLX and SPLX were recorded at λ ex  = λ em  = 330 nm. The detection limits were 3.8 ng ml -1 for GFLX and 17.5 ng ml -1 for SPLX at a signal-to-noise ratio of 3. The developed method was successfully applied to the determination of GFLX and SPLX in water samples. Recoveries from spiked water samples were 97.56-98.85%. Copyright © 2017 John Wiley & Sons, Ltd.

Analysis of alkyl phosphates in petroleum samples by comprehensive two-dimensional gas chromatography with nitrogen phosphorus detection and post-column Deans switching.

PubMed

Nizio, Katie D; Harynuk, James J

2012-08-24

Alkyl phosphate based gellants used as viscosity builders for fracturing fluids used in the process of hydraulic fracturing have been implicated in numerous refinery-fouling incidents in North America. In response, industry developed an inductively coupled plasma optical emission spectroscopy (ICP-OES) based method for the analysis of total volatile phosphorus in distillate fractions of crude oil; however, this method is plagued by poor precision and a high limit of detection (0.5±1μg phosphorus mL(-1)). Furthermore this method cannot provide speciation information, which is critical for developing an understanding of the challenge of alkyl phosphates at a molecular level. An approach using comprehensive two-dimensional gas chromatography with nitrogen phosphorus detection (GC×GC-NPD) and post-column Deans switching is presented. This method provides qualitative and quantitative profiles of alkyl phosphates in industrial petroleum samples with increased precision and at levels comparable to or below those achievable by ICP-OES. A recovery study in a fracturing fluid sample and a profiling study of alkyl phosphates in four recovered fracturing fluid/crude oil mixtures (flowback) are also presented. Copyright © 2012 Elsevier B.V. All rights reserved.

Liquid chromatography coupled to on-line post column derivatization for the determination of organic compounds: a review on instrumentation and chemistries.

PubMed

Zacharis, Constantinos K; Tzanavaras, Paraskevas D

2013-10-10

Analytical derivatization either in pre or post column modes is one of the most widely used sample pretreatment techniques coupled to liquid chromatography. In the present review article we selected to discuss the post column derivatization mode for the analysis of organic compounds. The first part of the review focuses to the instrumentation of post-column setups including not only fundamental components such as pumps and reactors but also less common parts such as static mixers and back-pressure regulators; the second part of the article discusses the most popular "chemistries" that are involved in post column applications, including reagent-less approaches and new sensing platforms such as the popular gold nanoparticles. Some representative recent applications are also presented as tables. Copyright © 2013 Elsevier B.V. All rights reserved.

Analysis of linear and cyclic oligomers in polyamide-6 without sample preparation by liquid chromatography using the sandwich injection method. II. Methods of detection and quantification and overall long-term performance.

PubMed

Mengerink, Y; Peters, R; Kerkhoff, M; Hellenbrand, J; Omloo, H; Andrien, J; Vestjens, M; van der Wal, S

2000-05-05

By separating the first six linear and cyclic oligomers of polyamide-6 on a reversed-phase high-performance liquid chromatographic system after sandwich injection, quantitative determination of these oligomers becomes feasible. Low-wavelength UV detection of the different oligomers and selective post-column reaction detection of the linear oligomers with o-phthalic dicarboxaldehyde (OPA) and 3-mercaptopropionic acid (3-MPA) are discussed. A general methodology for quantification of oligomers in polymers was developed. It is demonstrated that the empirically determined group-equivalent absorption coefficients and quench factors are a convenient way of quantifying linear and cyclic oligomers of nylon-6. The overall long-term performance of the method was studied by monitoring a reference sample and the calibration factors of the linear and cyclic oligomers.

Simple determination of aflatoxins in rice by ultra-high performance liquid chromatography coupled to chemical post-column derivatization and fluorescence detection.

PubMed

Huertas-Pérez, José Fernando; Arroyo-Manzanares, Natalia; Hitzler, Dominik; Castro-Guerrero, Francisco Germán; Gámiz-Gracia, Laura; García-Campaña, Ana M

2018-04-15

A fast and simple analytical method was developed and characterized for the determination of aflatoxins (B 1 , B 2 , G 1 and G 2 ) in rice. The procedure is based on a simple solid-liquid extraction without further clean-up, and analysis by ultra-high performance liquid chromatography coupled with fluorescence detection. Fluorescence emission of aflatoxins B 1 and G 1 was enhanced by post-column chemical derivatization using pyridinium bromide perbromide. The analytical method was satisfactorily characterized in white and brown rice. Under optimum conditions, external calibration in solvent could be used for quantification purposes and limits of quantification were below the maximum contents established by the European Union regulation for these contaminants/commodity group combination (0.07-0.14 µg/kg for white rice and 0.20-0.28 µg/kg for brown rice). Recovery studies carried out at three different concentration levels (0.5, 2 and 5 µg/kg) showed values in the range of 84.5-105.3%, and RSDs ≤ 5%. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rapid, Sensitive Detection of Botulinum Toxin on a Flexible Microfluidics Platform

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

Warner, Marvin G.; Dockendorff, Brian P.; Feldhaus, Michael J.

2004-10-30

In this paper we will describe how high affinity reagents and a sensor configuration enabling rapid mass transport can be combined for rapid, sensitive biodetection. The system that we have developed includes a renewable surface immunoassay, which involves on-column detection of a fluorescently labeled secondary antibody in a sandwich immunoassay. Yeast display and directed molecular evolution were used to create high affinity antibodies to the botulinum toxin heavy chain receptor binding domain, AR1 and 3D12. A rotating rod renewable surface microcolumn was used to form a microliter-sized column containing beads functionalized with the capture antibody (AR1). The column was perfusedmore » with sample, wash solutions, and a fluorescently labeled secondary antibody (3D12) while the on-column fluorescence was monitored. Detection was accomplished in less than 5 minutes, with a total processing time of about 10 minutes. On-column detection of botulinum toxin was more sensitive and much faster than flow cytometry analysis on microbeads using the same reagents.« less

First measurement of H I 21 cm emission from a GRB host galaxy indicates a post-merger system

NASA Astrophysics Data System (ADS)

Arabsalmani, Maryam; Roychowdhury, Sambit; Zwaan, Martin A.; Kanekar, Nissim; Michałowski, Michał J.

2015-11-01

We report the detection and mapping of atomic hydrogen in H I 21 cm emission from ESO 184-G82, the host galaxy of the gamma-ray burst 980425. This is the first instance where H I in emission has been detected from a galaxy hosting a gamma-ray burst (GRB). ESO 184-G82 is an isolated galaxy and contains a Wolf-Rayet region close to the location of the GRB and the associated supernova, SN 1998bw. This is one of the most luminous H II regions identified in the local Universe, with a very high inferred density of star formation. The H I 21 cm observations reveal a high H I mass for the galaxy, twice as large as the stellar mass. The spatial and velocity distribution of the H I 21 cm emission reveals a disturbed rotating gas disc, which suggests that the galaxy has undergone a recent minor merger that disrupted its rotation. We find that the Wolf-Rayet region and the GRB are both located in the highest H I column density region of the galaxy. We speculate that the merger event has resulted in shock compression of the gas, triggering extreme star formation activity, and resulting in the formation of both the Wolf-Rayet region and the GRB. The high H I column density environment of the GRB is consistent with the high H I column densities seen in absorption in the host galaxies of high-redshift GRBs.

Semi-automated hydrophobic interaction chromatography column scouting used in the two-step purification of recombinant green fluorescent protein.

PubMed

Stone, Orrin J; Biette, Kelly M; Murphy, Patrick J M

2014-01-01

Hydrophobic interaction chromatography (HIC) most commonly requires experimental determination (i.e., scouting) in order to select an optimal chromatographic medium for purifying a given target protein. Neither a two-step purification of untagged green fluorescent protein (GFP) from crude bacterial lysate using sequential HIC and size exclusion chromatography (SEC), nor HIC column scouting elution profiles of GFP, have been previously reported. Bacterial lysate expressing recombinant GFP was sequentially adsorbed to commercially available HIC columns containing butyl, octyl, and phenyl-based HIC ligands coupled to matrices of varying bead size. The lysate was fractionated using a linear ammonium phosphate salt gradient at constant pH. Collected HIC eluate fractions containing retained GFP were then pooled and further purified using high-resolution preparative SEC. Significant differences in presumptive GFP elution profiles were observed using in-line absorption spectrophotometry (A395) and post-run fluorimetry. SDS-PAGE and western blot demonstrated that fluorometric detection was the more accurate indicator of GFP elution in both HIC and SEC purification steps. Comparison of composite HIC column scouting data indicated that a phenyl ligand coupled to a 34 µm matrix produced the highest degree of target protein capture and separation. Conducting two-step protein purification using the preferred HIC medium followed by SEC resulted in a final, concentrated product with >98% protein purity. In-line absorbance spectrophotometry was not as precise of an indicator of GFP elution as post-run fluorimetry. These findings demonstrate the importance of utilizing a combination of detection methods when evaluating purification strategies. GFP is a well-characterized model protein, used heavily in educational settings and by researchers with limited protein purification experience, and the data and strategies presented here may aid in development other of HIC-compatible protein purification schemes.

Evolution in miniaturized column liquid chromatography instrumentation and applications: An overview.

PubMed

Nazario, Carlos E D; Silva, Meire R; Franco, Maraíssa S; Lanças, Fernando M

2015-11-20

The purpose of this article is to underline the miniaturized LC instrumental system and describe the evolution of commercially available systems by discussing their advantages and drawbacks. Nowadays, there are already many miniaturized LC systems available with a great variety of pump design, interface and detectors as well as efficient columns technologies and reduced connections devices. The solvent delivery systems are able to drive the mobile phase without flow splitters and promote gradient elution using either dual piston reciprocating or syringe-type pumps. The mass spectrometry as detection system is the most widely used detection system; among many alternative ionization sources direct-EI LC-MS is a promising alternative to APCI. In addition, capillary columns are now available showing many possibilities of stationary phases, inner diameters and hardware materials. This review provides a discussion about miniaturized LC demonstrating fundamentals and instrumentals' aspects of the commercially available miniaturized LC instrumental system mainly nano and micro LC formats. This review also covers the recent developments and trends in instrumentation, capillary and nano columns, and several applications of this very important and promising field. Copyright © 2015 Elsevier B.V. All rights reserved.

A novel thermal biosensor based on enzyme reaction for pesticides measurement.

PubMed

Zheng, Yi-Hu; Hua, Tse-Chao; Xu, Fei

2005-01-01

A novel thermal biosensor based on enzyme reaction for pesticides detection has been developed. This biosensor is a flow injection analysis system and consists of two channels with enzyme reaction column and identical reference column, which is set for eliminating the unspecific heat. The enzyme reaction takes place in the enzyme reaction column at a constant temperature (40 degrees C) realized by a thermoelectric thermostat. Thermosensor based on the thermoelectric module containing 127 serial BiTe-thermocouples is used to monitor the temperature difference between two effluents from enzyme reaction column and reference column. The ability of this biosensor to detect pesticides is demonstrated by the decreased degree of the hydrolytic heat in two types of thermosensor mode. The hydrolytic reaction is inhibited by 36% at 1 mg/L DDVP and 50% at 10 mg/L DDVP when cell-typed thermosensor is used. The percent inhibition is 30% at 1 mg/L DDVP and 42% at 10 mg/L DDVP in tube-typed thermosensor mode. The detection for real sample shows that this biosensor can be used for detection of organophosphate pesticides residue.

Determination of free formaldehyde in cosmetics containing formaldehyde-releasing preservatives by reversed-phase dispersive liquid-liquid microextraction and liquid chromatography with post-column derivatization.

PubMed

Miralles, Pablo; Chisvert, Alberto; Alonso, M José; Hernandorena, Sandra; Salvador, Amparo

2018-03-30

An analytical method for the determination of traces of formaldehyde in cosmetic products containing formaldehyde-releasing preservatives has been developed. The method is based on reversed-phase dispersive liquid-liquid microextraction (RP-DLLME), that allows the extraction of highly polar compounds, followed by liquid chromatography-ultraviolet/visible (LC-UV/vis) determination with post-column derivatization. The variables involved in the RP-DLLME process were studied to provide the best enrichment factors. Under the selected conditions, a mixture of 500 μL of acetonitrile (disperser solvent) and 50 μL of water (extraction solvent) was rapidly injected into 5 mL of toluene sample solution. The extracts were injected into the LC-UV/vis system using phosphate buffer 6 mmol L -1 at pH 2 as mobile phase. After chromatographic separation, the eluate merged with a flow stream of pentane-2,4-dione in ammonium acetate solution as derivatizing reagent and passed throughout a post-column reactor at 85 °C in order to derivatize formaldehyde into 3,5-diacetyl-1,4-dihydrolutidine, according to Hantzsch reaction, which was finally measured spectrophotometrically at 407 nm. The method was successfully validated showing good linearity, an enrichment factor of 86 ± 2, limits of detection and quantification of 0.7 and 2.3 ng mL -1 , respectively, and good repeatability (RSD < 9.2%). Finally, the proposed analytical method was applied to the determination of formaldehyde in different commercial cosmetic samples containing formaldehyde-releasing preservatives, such as bronopol, diazolidinyl urea, imidazolidinyl urea, and DMDM hydantoin, with good relative recovery values (91-113%) thus showing that matrix effects were negligible. The good analytical features of the proposed method besides of its simplicity and affordability, make it useful to carry out the quality control of cosmetic products containing formaldehyde-releasing preservatives. Copyright © 2018 Elsevier B.V. All rights reserved.

Sensitive method for the quantitation of droloxifene in plasma and serum by high-performance liquid chromatography employing fluorimetric detection.

PubMed

Tess, D A; Cole, R O; Toler, S M

1995-12-15

A simple and highly sensitive reversed-phase fluorimetric HPLC method for the quantitation of droloxifene from rat, monkey, and human plasma as well as human serum is described. This assay employs solid-phase extraction and has a dynamic range of 25 to 10,000 pg/ml. Sample extraction (efficiencies > 86%) was accomplished using a benzenesulfonic acid (SCX) column with water and methanol rinses. Droloxifene and internal standard were eluted with 1 ml of 3.5% (v/v) ammonium hydroxide (30%) in methanol. Samples were quantitated using post-column UV-photochemical cyclization coupled with fluorimetric detection with excitation and emission wavelengths of 260 nm and 375 nm, respectively. Relative ease of sample extraction and short run times allow for the analysis of approximately 100 samples per day.

Analysis of illegal peptide drugs via HILIC-DAD-MS.

PubMed

Janvier, Steven; De Sutter, Evelien; Wynendaele, Evelien; De Spiegeleer, Bart; Vanhee, Celine; Deconinck, Eric

2017-11-01

Biopharmaceuticals have established themselves as highly efficient medicines, and are still one of the fastest growing parts of the health-product industry. Unfortunately, the introduction of these promising new drugs went hand in hand with the creation of a black market for illegal and counterfeit biotechnology drugs. Particularly popular are the lyophilised peptides with a molecular weight of less than 5kDa. Most of them are meant for subcutaneous injection and are easily accessible via the internet. In recent years, different methods based on reversed phase liquid chromatography have been developed to detect and quantify these peptides. The emerging of more polar peptides however requires the introduction of other separation techniques. Therefore, we set out to develop and validate an analytical method based on hydrophilic interaction liquid chromatography (HILIC) to identify and quantify the most frequently encountered illegal peptides on the European market. For this objective, five different HILIC columns were selected and screened for their chromatographic performance. Among those columns, the ZIC HILIC column showed the best performance under the tested screening conditions in terms of resolution and symmetry factor for the targeted peptide set. Hence, the operational conditions were further optimised for the identification of illegal preparations via mass spectrometry (MS) and quantification via UV. Validation was performed via accuracy profiles based on the ISO 17025 guideline. The obtained validated HILIC-method allows for the detection and quantification of the most frequently encountered illegal peptides on the internet in a total run time of 35min including post gradient equilibration and online cleaning step. Combined with a previously developed RPLC-method, the ZIC HILIC system allows for the detection and quantification of a wide spectrum of illicit peptide drugs available on the internet. Furthermore, the developed method could also be envisaged for the detection of new emerging polar peptide drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of thimerosal in pharmaceutical industry effluents and river waters by HPLC coupled to atomic fluorescence spectrometry through post-column UV-assisted vapor generation.

PubMed

Acosta, Gimena; Spisso, Adrián; Fernández, Liliana P; Martinez, Luis D; Pacheco, Pablo H; Gil, Raúl A

2015-03-15

A high performance liquid chromatography coupled with atomic fluorescence spectrometry method for the determination of thimerosal (sodium ethylmercury thiosalicylate, C9H9HgNaO2S), ethylmercury, and inorganic mercury is proposed. Mercury vapor is generated by the post-column reduction of mercury species in formic acid media using UV-radiation. Thimerosal is quantitatively converted to Hg(II) followed by the reduction of Hg(II) to Hg(0). This method is applied to the determination of thimerosal (THM), ethylmercury (EtHg) and inorganic Hg in samples of a pharmaceutical industry effluent, and in waters of the San Luis River situated in the west side of San Luis city (Middle West, Argentine) where the effluents are dumped. The limit of detections, calculated on the basis of the 3σ criterion, where 0.09, 0.09 and 0.07 μg L(-1) for THM, EtHg(II) and for Hg(II), respectively. Linearity was attained from levels close to the detection limit up to at least 100 μg L(-1). Copyright © 2014 Elsevier B.V. All rights reserved.

Acoustic mapping of shallow water gas releases using shipborne multibeam systems

NASA Astrophysics Data System (ADS)

Urban, Peter; Köser, Kevin; Weiß, Tim; Greinert, Jens

2015-04-01

Water column imaging (WCI) shipborne multibeam systems are effective tools for investigating marine free gas (bubble) release. Like single- and splitbeam systems they are very sensitive towards gas bubbles in the water column, and have the advantage of the wide swath opening angle, 120° or more allowing a better mapping and possible 3D investigations of targets in the water column. On the downside, WCI data are degraded by specific noise from side-lobe effects and are usually not calibrated for target backscattering strength analysis. Most approaches so far concentrated on manual investigations of bubbles in the water column data. Such investigations allow the detection of bubble streams (flares) and make it possible to get an impression about the strength of detected flares/the gas release. Because of the subjective character of these investigations it is difficult to understand how well an area has been investigated by a flare mapping survey and subjective impressions about flare strength can easily be fooled by the many acoustic effects multibeam systems create. Here we present a semi-automated approach that uses the behavior of bubble streams in varying water currents to detect and map their exact source positions. The focus of the method is application of objective rules for flare detection, which makes it possible to extract information about the quality of the seepage mapping survey, perform automated noise reduction and create acoustic maps with quality discriminators indicating how well an area has been mapped.

Gas chromatographic column for the storage of sample profiles

NASA Technical Reports Server (NTRS)

Dimandja, J. M.; Valentin, J. R.; Phillips, J. B.

1994-01-01

The concept of a sample retention column that preserves the true time profile of an analyte of interest is studied. This storage system allows for the detection to be done at convenient times, as opposed to the nearly continuous monitoring that is required by other systems to preserve a sample time profile. The sample storage column is essentially a gas chromatography column, although its use is not the separation of sample components. The functions of the storage column are the selective isolation of the component of interest from the rest of the components present in the sample and the storage of this component as a function of time. Using octane as a test substance, the sample storage system was optimized with respect to such parameters as storage and readout temperature, flow rate through the storage column, column efficiency and storage time. A 3-h sample profile was collected and stored at 30 degrees C for 20 h. The profile was then retrieved, essentially intact, in 5 min at 130 degrees C.

Extraction and determination of biogenic amines in fermented sausages and other meat products using reversed-phase-HPLC.

PubMed

Straub, B; Schollenberger, M; Kicherer, M; Luckas, B; Hammes, W P

1993-09-01

A convenient method is described for the analysis of biogenic amines (BA) by means of reversed-phase-HPLC. The method is characterized by multi-channel UV detection (diodearray), subsequent post-column derivatization with o-phthaldialdehyde and 3-mercaptopropionic acid, and fluorescence detection. For the analysis of meat products and especially fermented sausages an optimized perchloric acid extraction process was introduced to determine putrescine, cadaverine, histamine, tyramine and 2-phenylethylamine. BA recoveries from meat ranged between 96 and 113% with a detection limit for amines of 0.5 mg/kg.

Gallium metal affinity capture tandem mass spectrometry for the selective detection of phosphopeptides in complex mixtures

PubMed Central

Blacken, Grady R.; Sadílek, Martin; Tureček, František

2008-01-01

Metal affinity capture tandem mass spectrometry (MAC-MSMS) is evaluated in a comparative study of a lysine-derived nitrilotriacetic acid (Nα, Nα-bis-(carboxymethyl)lysine, LysNTA) and an aspartic-acid-related iminodiacetic acid (N-(4-aminobutyl)aspartic acid, AspIDA) as selective phosphopeptide detection reagents. Both LysNTA and AspIDA spontaneously form ternary complexes with GaIII and phosphorylated amino acids and phosphopeptides upon mixing in solution. Collision-induced dissociation of positive complex ions produced by electrospray produces common fragments (LysNTA + H)+ or (AspIDA + H)+ at m/z 263 and 205, respectively. MSMS precursor scans using these fragments as reporter ions allow one to selectively detect multiple charge states of phosphopeptides in mixtures. It follows from this comparative study that LysNTA is superior to AspIDA in detecting phosphopeptides, possibly because of the higher coordination number and greater stability constant for GaIII – phosphopeptide complexation of the former reagent. In a continuing development of MAC-MSMS for proteomics applications, we demonstrate its utility in a post-column reaction format. Using a simple post-column-reaction ‘T’ and syringe pump to deliver our chelating reagents, α-casein tryptic phosphopeptides can be selectively analyzed from a solution containing a twofold molar excess of bovine serum albumin. The MAC-MSMS method is shown to be superior to the commonly used neutral loss scan for the common loss of phosphoric acid. PMID:18265438

Automated clean-up, separation and detection of polycyclic aromatic hydrocarbons in particulate matter extracts from urban dust and diesel standard reference materials using a 2D-LC/2D-GC system.

PubMed

Ahmed, Trifa M; Lim, Hwanmi; Bergvall, Christoffer; Westerholm, Roger

2013-10-01

A multidimensional, on-line coupled liquid chromatographic/gas chromatographic system was developed for the quantification of polycyclic aromatic hydrocarbons (PAHs). A two-dimensional liquid chromatographic system (2D-liquid chromatography (LC)), with three columns having different selectivities, was connected on-line to a two-dimensional gas chromatographic system (2D-gas chromatography (GC)). Samples were cleaned up by combining normal elution and column back-flush of the LC columns to selectively remove matrix constituents and isolate well-defined, PAH enriched fractions. Using this system, the sequential removal of polar, mono/diaromatic, olefinic and alkane compounds from crude extracts was achieved. The LC/GC coupling was performed using a fused silica transfer line into a programmable temperature vaporizer (PTV) GC injector. Using the PTV in the solvent vent mode, excess solvent was removed and the enriched PAH sample extract was injected into the GC. The 2D-GC setup consisted of two capillary columns with different stationary phase selectivities. Heart-cutting of selected PAH compounds in the first GC column (first dimension) and transfer of these to the second GC column (second dimension) increased the baseline resolutions of closely eluting PAHs. The on-line system was validated using the standard reference materials SRM 1649a (urban dust) and SRM 1975 (diesel particulate extract). The PAH concentrations measured were comparable to the certified values and the fully automated LC/GC system performed the clean-up, separation and detection of PAHs in 16 extracts in less than 24 h. The multidimensional, on-line 2D-LC/2D-GC system eliminated manual handling of the sample extracts and minimised the risk of sample loss and contamination, while increasing accuracy and precision.

Implications of soil mixing for NAPL source zone remediation: Column studies and modeling of field-scale systems

NASA Astrophysics Data System (ADS)

Olson, Mitchell R.; Sale, Tom C.

2015-06-01

Soil remediation is often inhibited by subsurface heterogeneity, which constrains contaminant/reagent contact. Use of soil mixing techniques for reagent delivery provides a means to overcome contaminant/reagent contact limitations. Furthermore, soil mixing reduces the permeability of treated soils, thus extending the time for reactions to proceed. This paper describes research conducted to evaluate implications of soil mixing on remediation of non-aqueous phase liquid (NAPL) source zones. The research consisted of column studies and subsequent modeling of field-scale systems. For column studies, clean influent water was flushed through columns containing homogenized soils, granular zero valent iron (ZVI), and trichloroethene (TCE) NAPL. Within the columns, NAPL depletion occurred due to dissolution, followed by either column-effluent discharge or ZVI-mediated degradation. Complete removal of TCE NAPL from the columns occurred in 6-8 pore volumes of flow. However, most of the TCE (> 96%) was discharged in the column effluent; less than 4% of TCE was degraded. The low fraction of TCE degraded is attributed to the short hydraulic residence time (< 4 days) in the columns. Subsequently, modeling was conducted to scale up column results. By scaling up to field-relevant system sizes (> 10 m) and reducing permeability by one-or-more orders of magnitude, the residence time could be greatly extended, potentially for periods of years to decades. Model output indicates that the fraction of TCE degraded can be increased to > 99.9%, given typical post-mixing soil permeability values. These results suggest that remediation performance can be greatly enhanced by combining contaminant degradation with an extended residence time.

Dual-wavelength light-emitting diode-based ultraviolet absorption detector for nano-flow capillary liquid chromatography.

PubMed

Xie, Xiaofeng; Tolley, Luke T; Truong, Thy X; Tolley, H Dennis; Farnsworth, Paul B; Lee, Milton L

2017-11-10

The design of a miniaturized LED-based UV-absorption detector was significantly improved for on-column nanoflow LC. The detector measures approximately 27mm×24mm×10mm and weighs only 30g. Detection limits down to the nanomolar range and linearity across 3 orders of magnitude were obtained using sodium anthraquinone-2-sulfonate as a test analyte. Using two miniaturized detectors, a dual-detector system was assembled containing 255nm and 275nm LEDs with only 216nL volume between the detectors A 100μm slit was used for on-column detection with a 150μm i.d. packed capillary column. Chromatographic separation of a phenol mixture was demonstrated using the dual-detector system, with each detector producing a unique chromatogram. Less than 6% variation in the ratios of absorbances measured at the two wavelengths for specific analytes was obtained across 3 orders of magnitude concentration, which demonstrates the potential of using absorption ratio measurements for target analyte detection. The dual-detector system was used for simple, but accurate, mobile phase flow rate measurement at the exit of the column. With a flow rate range from 200 to 2000nL/min, less than 3% variation was observed. Copyright © 2017 Elsevier B.V. All rights reserved.

Measurement of Menadione in Urine by HPLC

PubMed Central

Rajabi, Ala Al; Peterson, James; Choi, Sang Woon; Suttie, John; Barakat, Susan; Booth, Sarah L

2010-01-01

Menadione is a metabolite of vitamin K that is excreted in urine. A high performance liquid chromatography (HPLC) method using a C30 column, post-column zinc reduction and fluorescence detection was developed to measure urinary menadione. The mobile phase was composed of 95% methanol with 0.55% aqueous solution and 5% DI H2O. Menaquinone-2 (MK-2) was used as an internal standard. The standard calibration curve was linear with a correlation coefficient (R2) of 0.999 for both menadione and MK-2. The lower limit of quantification (LLOQ) was 0.3 pmole menadione/mL urine. Sample preparation involved hydrolysis of menadiol conjugates and oxidizing the released menadiol to menadione. Using this method, urinary menadione was shown to increase in response to 3 years of phylloquinone supplementation. This HPLC method is a sensitive and reproducible way to detect menadione in urine. Research support: USDA ARS Cooperative Agreement 58-1950-7-707. PMID:20719580

Measurement of menadione in urine by HPLC.

PubMed

Al Rajabi, Ala; Peterson, James; Choi, Sang-Woon; Suttie, John; Barakat, Susan; Booth, Sarah L

2010-09-15

Menadione is a metabolite of vitamin K that is excreted in urine. A high performance liquid chromatography (HPLC) method using a C(30) column, post-column zinc reduction and fluorescence detection was developed to measure urinary menadione. The mobile phase was composed of 95% methanol with 0.55% aqueous solution and 5% DI H(2)O. Menaquinone-2 (MK-2) was used as an internal standard. The standard calibration curve was linear with a correlation coefficient (R(2)) of 0.999 for both menadione and MK-2. The lower limit of quantification (LLOQ) was 0.3pmole menadione/mL urine. Sample preparation involved hydrolysis of menadiol conjugates and oxidizing the released menadiol to menadione. Using this method, urinary menadione was shown to increase in response to 3 years of phylloquinone supplementation. This HPLC method is a sensitive and reproducible way to detect menadione in urine. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Integrated enzyme reactor and high resolving chromatography in "sub-chip" dimensions for sensitive protein mass spectrometry.

PubMed

Hustoft, Hanne Kolsrud; Brandtzaeg, Ole Kristian; Rogeberg, Magnus; Misaghian, Dorna; Torsetnes, Silje Bøen; Greibrokk, Tyge; Reubsaet, Léon; Wilson, Steven Ray; Lundanes, Elsa

2013-12-16

Reliable, sensitive and automatable analytical methodology is of great value in e.g. cancer diagnostics. In this context, an on-line system for enzymatic cleavage of proteins, subsequent peptide separation by liquid chromatography (LC) with mass spectrometric detection has been developed using "sub-chip" columns (10-20 μm inner diameter, ID). The system could detect attomole amounts of isolated cancer biomarker progastrin-releasing peptide (ProGRP), in a more automatable fashion compared to previous methods. The workflow combines protein digestion using an 20 μm ID immobilized trypsin reactor with a polymeric layer of 2-hydroxyethyl methacrylate-vinyl azlactone (HEMA-VDM), desalting on a polystyrene-divinylbenzene (PS-DVB) monolithic trap column, and subsequent separation of resulting peptides on a 10 μm ID (PS-DVB) porous layer open tubular (PLOT) column. The high resolution of the PLOT columns was maintained in the on-line system, resulting in narrow chromatographic peaks of 3-5 seconds. The trypsin reactors provided repeatable performance and were compatible with long-term storage.

Development of at-line assay to monitor charge variants of MAbs during production.

PubMed

St Amand, M M; Ogunnaike, B A; Robinson, A S

2014-01-01

One major challenge currently facing the biopharmaceutical industry is to understand how MAb microheterogeneity affects therapeutic efficacy, potency, immunogenicity, and clearance. MAb micro-heterogeneity can result from post-translational modifications such as sialylation, galactosylation, C-terminal lysine cleavage, glycine amidation, and tryptophan oxidation, each of which can generate MAb charge variants; such heterogeneity can affect pharmacokinetics (PK) considerably. Implementation of appropriate on-line quality control strategies may help to regulate bioprocesses, thus enabling more homogenous material with desired post-translational modifications and PK behavior. However, one major restriction to implementation of quality control strategies is the availability of techniques for obtaining on-line or at-line measurements of these attributes. In this work, we describe the development of an at-line assay to separate MAb charge variants in near real-time, which could ultimately be used to implement on-line quality control strategies for MAb production. The assay consists of a 2D-HPLC method with sequential in-line Protein A and WCX-10 HPLC column steps. To perform the 2D-HPLC assay at-line, the two columns steps were integrated into a single method using a novel system configuration that allowed parallel flow over column 1 or column 2 or sequential flow from column 1 to column 2. A bioreactor system was also developed such that media samples could be removed automatically from bioreactor vessels during production and delivered to the 2D-HPLC for analysis. With this at-line HPLC assay, we have demonstrated that MAb microheterogeneity occurs throughout the cell cycle whether the host cell line is grown under different or the same nominal culture conditions. © 2013 American Institute of Chemical Engineers.

Enzymatic amplification of a flow-injected thermometric enzyme-linked immunoassay for human insulin.

PubMed

Mecklenburg, M; Lindbladh, C; Li, H; Mosbach, K; Danielsson, B

1993-08-01

A flow-injected thermometric enzyme linked immunoassay for human insulin which employs the lactate dehydrogenase/lactate oxidase (LDH/LOD) substrate recycling system for signal amplification is described. The system is composed of two columns, an immunosorbent column containing immobilized anti-insulin antibodies for sensing and a recycling column containing immobilized LDH/LOD/Catalase for detection. The effect of flow rates, conjugate concentrations, and chromatographic support material upon the sensitivity of the assay are investigated. The assay has a detection limit of 0.025 microgram/ml and a linear range from 0.05 to 2 micrograms/ml. This corresponds to a 10-fold increase in sensitivity over the unamplified system. A recombinant human insulin-proinsulin conjugate was also tested. The results show that enzymatic amplification can be employed to increase the sensitivity and reproducibility of flow injection assay-based biosensors. The implications of these results upon on-line analysis are discussed.

Development of gas chromatography-flame ionization detection system with a single column and liquid nitrogen-free for measuring atmospheric C2-C12 hydrocarbons.

PubMed

Liu, Chengtang; Mu, Yujing; Zhang, Chenglong; Zhang, Zhibo; Zhang, Yuanyuan; Liu, Junfeng; Sheng, Jiujiang; Quan, Jiannong

2016-01-04

A liquid nitrogen-free GC-FID system equipped with a single column has been developed for measuring atmospheric C2-C12 hydrocarbons. The system is consisted of a cooling unit, a sampling unit and a separation unit. The cooling unit is used to meet the temperature needs of the sampling unit and the separation unit. The sampling unit includes a dehydration tube and an enrichment tube. No breakthrough of the hydrocarbons was detected when the temperature of the enrichment tube was kept at -90 °C and sampling volume was 400 mL. The separation unit is a small round oven attached on the cooling column. A single capillary column (OV-1, 30 m × 0.32 mm I.D.) was used to separate the hydrocarbons. An optimal program temperature (-60 ∼ 170 °C) of the oven was achieved to efficiently separate C2-C12 hydrocarbons. There were good linear correlations (R(2)=0.993-0.999) between the signals of the hydrocarbons and the enrichment amount of hydrocarbons, and the relative standard deviation (RSD) was less than 5%, and the method detection limits (MDLs) for the hydrocarbons were in the range of 0.02-0.10 ppbv for sampling volume of 400 mL. Field measurements were also conducted and more than 50 hydrocarbons from C2 to C12 were detected in Beijing city. Copyright © 2015 Elsevier B.V. All rights reserved.

Dog erythrocyte antigens 1.1, 1.2, 3, 4, 7, and Dal blood typing and cross-matching by gel column technique.

PubMed

Kessler, Rebecca J; Reese, Jessica; Chang, Denise; Seth, Mayank; Hale, Anne S; Giger, Urs

2010-09-01

Testing for canine blood types other than dog erythrocyte antigen 1.1 (DEA 1.1) is controversial and complicated by reagent availability and methodology. The objectives of this study were to use available gel column technology to develop an extended blood-typing method using polyclonal reagents for DEA 1.1, 1.2, 3, 4, 7, and Dal and to assess the use of gel columns for cross-matching. Dogs (43-75) were typed for DEA 1.1, 1.2, 3, 4, 7, and Dal. METHODS included tube agglutination (Tube) using polyclonal reagents, a commercially available DEA 1.1 gel column test kit (Standard-Gel) using monoclonal reagent, and multiple gel columns (Extended-Gel) using polyclonal reagents. Blood from 10 recipient and 15 donor dogs was typed as described above and cross-matched using the gel column technique. Of 43 dogs typed for DEA 1.1, 23, 25, and 20 dogs were positive using Standard-Gel, Extended-Gel, and Tube, respectively. Typing for DEA 1.2 was not achievable with Extended-Gel. For 75 dogs typed for DEA 3, 4, and 7, concordance of Extended-Gel with Tube was 94.7%, 100%, and 84%, respectively. Dal, determined only by Extended-Gel, was positive for all dogs. Post-transfusion major cross-matches were incompatible in 10 of 14 pairings, but none were associated with demonstrable blood type incompatibilities. Gel column methodology can be adapted for use with polyclonal reagents for detecting DEA 1.1, 3, 4, 7, and Dal. Agglutination reactions are similar between Extended-Gel and Tube, but are more easily interpreted with Extended-Gel. When using gel columns for cross-matching, incompatible blood cross-matches can be detected following sensitization by transfusion, although in this study incompatibilities associated with any tested DEA or Dal antigens were not found. ©2010 American Society for Veterinary Clinical Pathology.

Column CO2 Measurement From an Airborne Solid-State Double-Pulsed 2-Micron Integrated Path Differential Absorption Lidar

NASA Technical Reports Server (NTRS)

Singh, U. N.; Yu, J.; Petros, M.; Refaat, T. F.; Remus, R.; Fay, J.; Reithmaier, K.

2014-01-01

NASA LaRC is developing and integrating a double-Pulsed 2-micron direct detection IPDA lidar for CO2 column measurement from an airborne platform. The presentation will describe the development of the 2-micrometers IPDA lidar system and present the airborne measurement of column CO2 and will compare to in-situ measurement for various ground target of different reflectivity.

Implications of soil mixing for NAPL source zone remediation: Column studies and modeling of field-scale systems.

PubMed

Olson, Mitchell R; Sale, Tom C

2015-01-01

Soil remediation is often inhibited by subsurface heterogeneity, which constrains contaminant/reagent contact. Use of soil mixing techniques for reagent delivery provides a means to overcome contaminant/reagent contact limitations. Furthermore, soil mixing reduces the permeability of treated soils, thus extending the time for reactions to proceed. This paper describes research conducted to evaluate implications of soil mixing on remediation of non-aqueous phase liquid (NAPL) source zones. The research consisted of column studies and subsequent modeling of field-scale systems. For column studies, clean influent water was flushed through columns containing homogenized soils, granular zero valent iron (ZVI), and trichloroethene (TCE) NAPL. Within the columns, NAPL depletion occurred due to dissolution, followed by either column-effluent discharge or ZVI-mediated degradation. Complete removal of TCE NAPL from the columns occurred in 6-8 pore volumes of flow. However, most of the TCE (>96%) was discharged in the column effluent; less than 4% of TCE was degraded. The low fraction of TCE degraded is attributed to the short hydraulic residence time (<4 days) in the columns. Subsequently, modeling was conducted to scale up column results. By scaling up to field-relevant system sizes (>10 m) and reducing permeability by one-or-more orders of magnitude, the residence time could be greatly extended, potentially for periods of years to decades. Model output indicates that the fraction of TCE degraded can be increased to >99.9%, given typical post-mixing soil permeability values. These results suggest that remediation performance can be greatly enhanced by combining contaminant degradation with an extended residence time. Copyright © 2015 Elsevier B.V. All rights reserved.

Semi-Automated Hydrophobic Interaction Chromatography Column Scouting Used in the Two-Step Purification of Recombinant Green Fluorescent Protein

PubMed Central

Murphy, Patrick J. M.

2014-01-01

Background Hydrophobic interaction chromatography (HIC) most commonly requires experimental determination (i.e., scouting) in order to select an optimal chromatographic medium for purifying a given target protein. Neither a two-step purification of untagged green fluorescent protein (GFP) from crude bacterial lysate using sequential HIC and size exclusion chromatography (SEC), nor HIC column scouting elution profiles of GFP, have been previously reported. Methods and Results Bacterial lysate expressing recombinant GFP was sequentially adsorbed to commercially available HIC columns containing butyl, octyl, and phenyl-based HIC ligands coupled to matrices of varying bead size. The lysate was fractionated using a linear ammonium phosphate salt gradient at constant pH. Collected HIC eluate fractions containing retained GFP were then pooled and further purified using high-resolution preparative SEC. Significant differences in presumptive GFP elution profiles were observed using in-line absorption spectrophotometry (A395) and post-run fluorimetry. SDS-PAGE and western blot demonstrated that fluorometric detection was the more accurate indicator of GFP elution in both HIC and SEC purification steps. Comparison of composite HIC column scouting data indicated that a phenyl ligand coupled to a 34 µm matrix produced the highest degree of target protein capture and separation. Conclusions Conducting two-step protein purification using the preferred HIC medium followed by SEC resulted in a final, concentrated product with >98% protein purity. In-line absorbance spectrophotometry was not as precise of an indicator of GFP elution as post-run fluorimetry. These findings demonstrate the importance of utilizing a combination of detection methods when evaluating purification strategies. GFP is a well-characterized model protein, used heavily in educational settings and by researchers with limited protein purification experience, and the data and strategies presented here may aid in development other of HIC-compatible protein purification schemes. PMID:25254496

3D-printed lab-on-valve for fluorescent determination of cadmium and lead in water.

PubMed

Mattio, Elodie; Robert-Peillard, Fabien; Vassalo, Laurent; Branger, Catherine; Margaillan, André; Brach-Papa, Christophe; Knoery, Joël; Boudenne, Jean-Luc; Coulomb, Bruno

2018-06-01

In recent years, the development of 3D printing in flow analysis has allowed the creation of new systems with various applications. Up to now, 3D printing was mainly used for the manufacture of small units such as flow detection cells, preconcentration units or mixing systems. In the present study, a new 3D printed lab-on-valve system was developed to selectively quantify lead and cadmium in water. Different technologies were compared for lab-on-valve 3D printing. Printed test units have shown that stereolithography or digital light processing are satisfactory techniques for creating complex lab-on-valve units. The lab-on-valve system was composed of two columns, eight peripheral ports and a central port, and a coil integrating baffles to increase mixing possibilities. A selective extraction of lead was first carried out by TrisKem Pb™ Resin column. Then, cadmium not retained on the first column was extracted on a second column of Amberlite® IR 120 resin. In a following step, lead and cadmium were eluted with ammonium oxalate and potassium iodide, respectively. Finally, the two metals were sequentially detected by the same Rhod-5N™ fluorescent reagent. This 3D printed lab-on-valve flow system allowed us to quantify lead and cadmium with a linear response from 0.2 to 15 µg L -1 and detection limits of 0.17 and 0.20 µg L -1 for lead and cadmium, respectively, which seems adapted for natural water analysis. Copyright © 2018 Elsevier B.V. All rights reserved.

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.

Design, Development, and Testing of a Network Frequency Selection Service (NFSS)

DTIC Science & Technology

1994-02-14

mercial simulation software (Sim++), word processor ( FrameMaker ), editor (Gnu Emacs), software ver- sion control (Revision Control System (RCS)), system...of FrameMaker ".mif" files. When viewed using FrameMaker or a PostScript reader, each page of results appears as two columns by four rows of graphics

Glass-silicon column

DOEpatents

Yu, Conrad M.

2003-12-30

A glass-silicon column that can operate in temperature variations between room temperature and about 450.degree. C. The glass-silicon column includes large area glass, such as a thin Corning 7740 boron-silicate glass bonded to a silicon wafer, with an electrode embedded in or mounted on glass of the column, and with a self alignment silicon post/glass hole structure. The glass/silicon components are bonded, for example be anodic bonding. In one embodiment, the column includes two outer layers of silicon each bonded to an inner layer of glass, with an electrode imbedded between the layers of glass, and with at least one self alignment hole and post arrangement. The electrode functions as a column heater, and one glass/silicon component is provided with a number of flow channels adjacent the bonded surfaces.

Seismic testing of precast segmental bridges, Phase III : bridge system test.

DOT National Transportation Integrated Search

2005-06-01

This report discusses the main findings of a test examining the seismic behavior of a precast, post-tensioned, segmental bridge : superstructure with a cast-in-place, hollow, rectangular column. The half-scale specimen modeled a prototype bridge from...

Nondestructive evaluation of the preservation state of stone columns in the Hospital Real of Granada

NASA Astrophysics Data System (ADS)

Moreno de Jong van Coevorden, C.; Cobos Sánchez, C.; Rubio Bretones, A.; Fernández Pantoja, M.; García, Salvador G.; Gómez Martín, R.

2012-12-01

This paper describes the results of the employment of two nondestructive evaluation methods for the diagnostic of the preservation state of stone elements. The first method is based on ultrasonic (US) pulses while the second method uses short electromagnetic pulses. Specifically, these methods were applied to some columns, some of them previously restored. These columns are part of the architectonic heritage of the University of Granada, in particular they are located at the patio de la capilla del Hospital Real of Granada. The objective of this work was the application of systems based on US pulses (in transmission mode) and the ground-penetrating radar systems (electromagnetic tomography) in the diagnosis and detection of possible faults in the interior of columns.

Quantitative analysis of cell columns in the cerebral cortex.

PubMed

Buxhoeveden, D P; Switala, A E; Roy, E; Casanova, M F

2000-04-01

We present a quantified imaging method that describes the cell column in mammalian cortex. The minicolumn is an ideal template with which to examine cortical organization because it is a basic unit of function, complete in itself, which interacts with adjacent and distance columns to form more complex levels of organization. The subtle details of columnar anatomy should reflect physiological changes that have occurred in evolution as well as those that might be caused by pathologies in the brain. In this semiautomatic method, images of Nissl-stained tissue are digitized or scanned into a computer imaging system. The software detects the presence of cell columns and describes details of their morphology and of the surrounding space. Columns are detected automatically on the basis of cell-poor and cell-rich areas using a Gaussian distribution. A line is fit to the cell centers by least squares analysis. The line becomes the center of the column from which the precise location of every cell can be measured. On this basis several algorithms describe the distribution of cells from the center line and in relation to the available surrounding space. Other algorithms use cluster analyses to determine the spatial orientation of every column.

Two fatal intoxication cases with imidacloprid: LC/MS analysis.

PubMed

Proença, Paula; Teixeira, Helena; Castanheira, Fernando; Pinheiro, João; Monsanto, Paula V; Marques, Estela P; Vieira, Duarte Nuno

2005-10-04

Imidacloprid [1-(6-chloro-3pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine] is a new and potent nitromethylene insecticide with high insecticidal activity at very low application rates. It is the first highly effective insecticide that, like nicotine, acts on the nervous system, causing blockage of postsynaptic nicotinergic acetylcholine receptors. Two fatal cases with this insecticide in two male individuals, of 33 and 66 years old, are presented. An LC/MS with electrospray method for measuring imidacloprid and its metabolites in post-mortem samples is described. In the chromatographic separation, a reverse-phase column XTerra MS C18 (2.1mm i.d.x 150 mm, 5 microm) was used and the mobile phase composed with acetonitrile and 0.1% formic acid (15:85), at a 0.25 mL/min flow rate. Samples were prepared with a liquid-liquid extraction procedure with dichloromethane. Calibration curves for imidacloprid in blood and urine samples were linear from 0.2 to 15 microg/mL. The mean recovery was 86% with a coefficient of variation of +/-5.9%. The detection limit was 0.002 microg/mL. Quantitative results were obtained for all post-mortem matrices available of the two fatal cases: blood, urine, stomach contents, lung, liver and kidney. The imidacloprid blood concentrations found in two-cases were 12.5 and 2.05 microg/mL. The authors validated a method to detect and quantify imidacloprid in post-mortem samples, and to our knowledge for the first time a post-mortem tissue distribution was performed on various samples for this insecticide.

One-pot preparation of a mixed-mode organic-silica hybrid monolithic capillary column and its application in determination of endogenous gibberellins in plant tissues.

PubMed

Zhang, Zheng; Hao, Yan-Hong; Ding, Jun; Xu, Sheng-Nan; Yuan, Bi-Feng; Feng, Yu-Qi

2015-10-16

A newly improved one-pot method, based on "thiol-ene" click chemistry and sol-gel approach in microemulsion system, was developed for the preparation of C8/PO(OH)2-silica hybrid monolithic capillary column. The prepared monolith possesses large specific surface area, narrow mesopore size distribution and high column efficiency. The monolithic column was demonstrated to have cation exchange/reversed-phase (CX/RP) mixed-mode retention for analytes on nano-liquid chromatography (nano-LC). On the basis of the developed nano-LC system with MS detector coupled to pipette tip solid phase extraction (PT-SPE) and derivatization process, we then realized simultaneous determination of 10 gibberellins (GAs) with low limits of detection (LODs, 0.003-0.025 ng/mL). Furthermore, 6 endogenous GAs in only 5mg rice leaves (fresh weight) were successfully detected and quantified. The developed PT-SPE-nano-LC-MS strategy may offer promising applications in the determination of low abundant bioactive molecules from complex matrix. Copyright © 2015 Elsevier B.V. All rights reserved.

The differences in matrix effect between supercritical fluid chromatography and reversed phase liquid chromatography coupled to ESI/MS.

PubMed

Svan, Alfred; Hedeland, Mikael; Arvidsson, Torbjörn; Pettersson, Curt E

2018-02-13

For many sample matrices, matrix effects are a troublesome phenomenon using the electrospray ionization source. The increasing use of supercritical fluid chromatography with CO 2 in combination with the electrospray ionization source for MS detection is therefore raising questions: is the matrix effect behaving differently using SFC in comparison with reversed phase LC? This was investigated using urine, plasma, influent- and effluent-wastewater as sample matrices. The matrix effect was evaluated using the post-extraction addition method and through post-column infusions. Matrix effect profiles generated from the post-column infusions in combination with time of flight-MS detection provided the most valuable information for the study. The combination of both qualitative and semi-quantitative information with the ability to use HRMS-data for identifying interfering compounds from the same experiment was very useful, and has to the authors' knowledge not been used this way before. The results showed that both LC and SFC are affected by matrix effects, however differently depending on sample matrix. Generally, both suppressions and enhancements were seen, with a higher amount of enhancements for LC, where 65% of all compounds and all sample matrices were enhanced, compared to only 7% for SFC. Several interferences were tentatively identified, with phospholipids, creatinine, and metal ion clusters as examples of important interferences, with different impact depending on chromatographic technique. SFC needs a different strategy for limiting matrix interferences, owing to its almost reverse retention order compared to RPLC. Copyright © 2017 Elsevier B.V. All rights reserved.

Radionuclide Sensors and Systems for Monitoring Technetium-99 and Strontium-90 in Groundwater at the Hanford Site

NASA Astrophysics Data System (ADS)

Grate, J. W.; O'Hara, M. J.; Egorov, O. B.; Burge, S. R.

2009-12-01

We have developed automated sensor and analyzer devices for detection and monitoring of trace radionuclides in water, using preconcentrating columns and radiometric detection. The preconcentrating minicolumn sensor concept combines selective capture and detection in a single functional unit, where the column contains tens to hundreds of milligrams of selectively sorbent material, and the entire column content is monitored with a radiometric detector. Compared to thin film sensors with a few microgram of sorbent, this approach achieves tremendous preconcentration with efficient mass transport via pumping. Furthermore, in an equilibration-based mode of operation, the preconcentration by the sensor is maximized while eliminating the need for consumable reagents to regenerate the column; it can simply be re-equilibrated. We have demonstrated quantification of radionuclides such as technetium-99 to levels below drinking water standards in an equilibration-based process that produces steady state signals, signal proportional to concentration, and easy re-equilibration to new concentration levels. Alternatively, analyzers can be developed with separate separation and detection units that are fluidically linked. We have demonstrated detection of strontium-90 to levels below drinking water standards by this approach. We are developing autonomous systems for at-site monitoring on the Hanford Site in Washington State, using the fluidic sensor and analyzer methods, with the aim of monitoring natural and accelerated attenuation processes, remediation and barrier performance, and contaminant fluxes in the environment. Figure 1. The strontium-90 monitoring method deployed as part of the Burge Environmental Universal Sensor Platform, shown on the shores of the Columbia River on the Hanford site in Washington State.

Determination of Aflatoxins and Ochratoxin A in Traditional Turkish Concentrated Fruit Juice Products by Multi-Immunoaffinity Column Cleanup and LC Fluorescence Detection: Single-Laboratory Validation.

PubMed

Kaymak, Tugrul; Türker, Levent; Tulay, Hüseyin; Stroka, Joerg

2018-04-27

Background : Pekmez and pestil are traditional Turkish foods made from concentrated grapejuice, which can be contaminated with mycotoxins such as aflatoxins and ochratoxin A (OTA). Objective : To carry out a single-laboratory validation of a method to simultaneously determine aflatoxins B 1 , B₂, G 1 , and G₂ and ochratoxin A in pekmez and pestil. Methods : The homogenized sample is extracted with methanol-water (80 + 20) using a high-speed blender. The (sample) extract is filtered, diluted with phosphate-buffered saline solution, and applied to a multi-immunoaffinity column (AFLAOCHRA PREP®). Aflatoxins and ochratoxin A are removed with (neat) methanol and then directly analyzed by reversed-phase LC with fluorescence detection using post-column bromination (Kobra cell®). Results : Test portions of blank pekmez and pestil were spiked with a mixture of aflatoxins and ochratoxin A to give levels ranging from 2.6 to 10.4 μg/kg and 1.0-4.0 μg/kg, respectively. Recoveries for total aflatoxins and ochratoxin A ranged from 84 to 106% and 80-97%, respectively, for spiked samples. Based on results for spiked pekmez and pestil (30 replicates each at three levels), the repeatability RSD ranged from 1.6 to 12% and 2.7-11% for total aflatoxins and ochratoxin A, respectively. Conclusions : The method performance in terms of recovery, repeatability, and detection limits has been demonstrated to be suitable for use as an Official Method. Highlights : First immunoaffinity column method validated for simultaneous analysis of aflatoxins and ochratoxin A in pekmez and pestil. Suitability for use for official purposes in Turkey, demonstrated by single-laboratory validation. Co-occurrence of aflatoxins and OTA in mulberry and carob pekmez reported for the first time.

Development of High Precision Metal Micro-Electro-Mechanical-Systems Column for Portable Surface Acoustic Wave Gas Chromatograph

NASA Astrophysics Data System (ADS)

Iwaya, Takamitsu; Akao, Shingo; Sakamoto, Toshihiro; Tsuji, Toshihiro; Nakaso, Noritaka; Yamanaka, Kazushi

2012-07-01

In the field of environmental measurement and security, a portable gas chromatograph (GC) is required for the on-site analysis of multiple hazardous gases. Although the gas separation column has been downsized using micro-electro-mechanical-systems (MEMS) technology, an MEMS column made of silicon and glass still does not have sufficient robustness and a sufficiently low fabrication cost for a portable GC. In this study, we fabricated a robust and inexpensive high-precision metal MEMS column by combining diffusion-bonded etched stainless-steel plates with alignment evaluation using acoustic microscopy. The separation performance was evaluated using a desktop GC with a flame ionization detector and we achieved the high separation performance comparable to the best silicon MEMS column fabricated using a dynamic coating method. As an application, we fabricated a palm-size surface acoustic wave (SAW) GC combining this column with a ball SAW sensor and succeeded in separating and detecting a mixture of volatile organic compounds.

Dispersal of post-larval macrobenthos in subtidal sedimentary habitats: Roles of vertical diel migration, water column, bedload transport and biological traits' expression

NASA Astrophysics Data System (ADS)

Pacheco, Aldo S.; Uribe, Roberto A.; Thiel, Martin; Oliva, Marcelo E.; Riascos, Jose M.

2013-03-01

Post-larval dispersal along the sediment-water interface is an important process in the dynamics of macrobenthic populations and communities in marine sublittoral sediments. However, the modes of post-larval dispersal in low energy sublittoral habitats have been poorly documented. Herein we examined the specific dispersal mechanisms (diel vertical migration, water column, and bedload transport) and corresponding biological traits of the dispersing assemblage. At two sublittoral sites (sheltered and exposed) along the northern coast of Chile, we installed different trap types that capture benthic organisms with specific modes of dispersal (active emergence and passive water column drifting) and also by a combination of mechanisms (bedload transport, passive suspension and settlement from the water column). Our results show that even though there were common species in all types of traps, the post-larval macrobenthic assemblage depended on specific mechanisms of dispersal. At the sheltered site, abundant emerging taxa colonized sediments that were placed 0.5 m above the bottom and bedload-transported invertebrates appeared to be associated to the passive drifting of macroalgae. At the exposed site, assemblage dispersal was driven by specific mechanisms e.g. bedload transport and active emergence. At both sites the biological traits "small size, swimming, hard exoskeleton, free living and surface position" were associated to water column and bedload dispersal. This study highlights the importance of (i) the water-sediment interface for dispersal of post-larvae in sublittoral soft-bottom habitat, and (ii) a specific set of biological traits when dispersing either along the bottom or through the water column.

Algorithms used in the Airborne Lidar Processing System (ALPS)

USGS Publications Warehouse

Nagle, David B.; Wright, C. Wayne

2016-05-23

The Airborne Lidar Processing System (ALPS) analyzes Experimental Advanced Airborne Research Lidar (EAARL) data—digitized laser-return waveforms, position, and attitude data—to derive point clouds of target surfaces. A full-waveform airborne lidar system, the EAARL seamlessly and simultaneously collects mixed environment data, including submerged, sub-aerial bare earth, and vegetation-covered topographies.ALPS uses three waveform target-detection algorithms to determine target positions within a given waveform: centroid analysis, leading edge detection, and bottom detection using water-column backscatter modeling. The centroid analysis algorithm detects opaque hard surfaces. The leading edge algorithm detects topography beneath vegetation and shallow, submerged topography. The bottom detection algorithm uses water-column backscatter modeling for deeper submerged topography in turbid water.The report describes slant range calculations and explains how ALPS uses laser range and orientation measurements to project measurement points into the Universal Transverse Mercator coordinate system. Parameters used for coordinate transformations in ALPS are described, as are Interactive Data Language-based methods for gridding EAARL point cloud data to derive digital elevation models. Noise reduction in point clouds through use of a random consensus filter is explained, and detailed pseudocode, mathematical equations, and Yorick source code accompany the report.

Trace-Level Automated Mercury Speciation Analysis

PubMed Central

Taylor, Vivien F.; Carter, Annie; Davies, Colin; Jackson, Brian P.

2011-01-01

An automated system for methyl Hg analysis by purge and trap gas chromatography (GC) was evaluated, with comparison of several different instrument configurations including chromatography columns (packed column or capillary), detector (atomic fluorescence, AFS, or inductively coupled plasma mass spectrometry, ICP-MS, using quadrupole and sector field ICP- MS instruments). Method detection limits (MDL) of 0.042 pg and 0.030 pg for CH3Hg+ were achieved with the automated Hg analysis system configured with AFS and ICPMS detection, respectively. Capillary GC with temperature programming was effective in improving resolution and decreasing retention times of heavier Hg species (in this case C3H7Hg+) although carryover between samples was increased. With capillary GC, the MDL for CH3Hg+ was 0.25 pg for AFS detection and 0.060 pg for ICP-MS detection. The automated system was demonstrated to have high throughput (72 samples analyzed in 8 hours) requiring considerably less analyst time than the manual method for methyl mercury analysis described in EPA 1630. PMID:21572543

Enhanced capabilities of separation in Sequential Injection Chromatography--fused-core particle column and its comparison with narrow-bore monolithic column.

PubMed

Chocholouš, Petr; Kosařová, Lucie; Satínský, Dalibor; Sklenářová, Hana; Solich, Petr

2011-08-15

In the Sequential Injection Chromatography (SIC) only monolithic columns for chromatographic separations have been used so far. This article presents the first use of fused-core particle packed column in an attempt to extend of the chromatographic capabilities of the SIC system. A new fused-core particle column (2.7 μm) Ascentis(®) Express C18 (Supelco™ Analytical) 30 mm × 4.6 mm brings high separation efficiency within flow rates and pressures comparable to monolithic column Chromolith(®) Performance RP-18e 100-3 (Merck(®)) 100 mm × 3 mm. Both columns matches the conditions of the commercially produced SIC system - SIChrom™ (8-port high-pressure selection valve and medium-pressure Sapphire™ syringe pump with 4 mL reservoir - maximal work pressure 1000 PSI) (FIAlab(®), USA). The system was tested by the separation of four estrogens with similar structure and an internal standard - ethylparaben. The mobile phase composed of acetonitrile/water (40/60 (v/v)) was pumped isocratic at flow rate 0.48 mL min(-1). Spectrophotometric detection was performed at wavelength of 225 nm and injected volume of sample solutions was 10 μL. The chromatographic characteristics of both columns were compared. Obtained results and conclusions have shown that both fused-core particle column and longer narrow shaped monolithic column bring benefits into the SIC method. Copyright © 2011 Elsevier B.V. All rights reserved.

Experimental and Analytical Seismic Studies of a Four-Span Bridge System with Innovative Materials

NASA Astrophysics Data System (ADS)

Cruz Noguez, Carlos Alonso

As part of a multi-university project utilizing the NSF Network for Earthquake Engineering Simulation (NEES), a quarter-scale model of a four-span bridge incorporating plastic hinges with different advanced materials was tested to failure on the three shake table system at the University of Nevada, Reno (UNR). The bridge was the second test model in a series of three 4-span bridges, with the first model being a conventional reinforced-concrete (RC) structure. The purpose of incorporating advanced materials was to improve the seismic performance of the bridge with respect to two damage indicators: (1) column damage and (2) permanent deformations. The goals of the study presented in this document were to (1) evaluate the seismic performance of a 4-span bridge system incorporating SMA/ECC and built-in rubber pad plastic hinges as well as post-tensioned piers, (2) quantify the relative merit of these advanced materials and details compared to each other and to conventional reinforced concrete plastic hinges, (3) determine the influence of abutment-superstructure interaction on the response, (4) examine the ability of available elaborate analytical modeling techniques to model the performance of advanced materials and details, and (5) conduct an extensive parametric study of different variations of the bridge model to study several important issues in bridge earthquake engineering. The bridge model included six columns, each pair of which utilized a different advanced detail at bottom plastic hinges: shape memory alloys (SMA), special engineered cementitious composites (ECC), elastomeric pads embedded into columns, and post-tensioning tendons. The design of the columns, location of the bents, and selection of the loading protocol were based on pre-test analyses conducted using computer program OpenSees. The bridge model was subjected to two-horizontal components of simulated earthquake records of the 1994 Northridge earthquake. Over 340 channels of data were collected. The test results showed the effectiveness of the advanced materials in reducing damage and permanent displacements. The damage was minimal in plastic hinges with SMA/ECC and those with built-in elastomeric pads. Conventional RC plastic hinges were severely damaged due to spalling of concrete and rupture of the longitudinal and transverse reinforcement. Extensive post-test analytical studies were conducted and it was determined that a computational model of the bridge that included bridge-abutment interaction using OpenSees was able to provide satisfactory estimations of key structural parameters such as superstructure displacements and base shears. The analytical model was also used to conduct parametric studies on single-column and bridge-system response under near-fault ground motions. The effects of vertical excitations and transverse shear-keys at the bridge abutments on the superstructure displacement and column drifts were also explored.

Simultaneous modelling of X-ray emission and optical polarization of intermediate polars: the case of V405 Aur

NASA Astrophysics Data System (ADS)

J. Lima, I.; Vilega Rodrigues, C.; Medeiros Gomes Silva, K.; Luna, G.; D Amico, F.; Goulart Coelho, J.

2017-10-01

Intermediate polars are compact binaries in which mass transfer occurs from a low-mass star onto a magnetic white dwarf. A shock structure is formed in the magnetic accretion column nearby the white-dwarf surface. High-energy emission is produced in the post-shock region and the main physical process envolved is bremsstrahlung and line emission. Some systems show optical polarization, which may be also originated in the post-shock region. Our main goal is to study the magnetic structure of intermediate polars by simultaneously modelling optical polarimetry and X-ray data using the CYCLOPS code. This code was developed by our group to peform multi-wavelength fitting of the accretion column flux. It considers cyclotron and free-free emission from a 3D post-shock region, which is non-homogeneous in terms of density, temperature, and magnetic field. In this study, we present our modelling of the optical polarization and X-ray emission of V405 Aurigae, the intermediate polar that has the highest magnetic field. Previous studies of this system were not successful in proposing a geometry that explains both the optical and X-ray emissions.

Rapid determination of five antibiotic residues in swine wastewater by online solid-phase extraction-high performance liquid chromatography-tandem mass spectrometry.

PubMed

Tagiri-Endo, Misako; Suzuki, Shigeru; Nakamura, Tomoyuki; Hatakeyama, Takashi; Kawamukai, Kazuo

2009-02-01

A simple and quick online solid-phase extraction (SPE) coupled to liquid chromatography (LC)/tandem mass spectrometry (MS/MS) for the determination of the five antibiotics (florfenicol, FF; lincomycin, LCM; oxytetracyclin, OTC; tylosin, TS; valnemulin, VLM) in swine wastewater has been developed. After filtration, aliquots (100 microl) of wastewater samples were directly injected to a column-switching LC system. Some matrix interference was removed by washing up SPE column with 0.2% formic acid solution and acetonitrile. Antibiotics eluted from SPE column were separated on analytical column by converting switching valve and were detected by MS/MS. Calibration curves using the method of standard addition had very good correlation coefficients (r > 0.99) in the range of 0.1 to 2 ng/ml. The intra-day precision of the method was less than 12% and the inter-day precision was between 6 to 17%. The detection limits were 0.01-0.1 ng/ml. When this method was applied to wastewater samples in swine facilities, four compounds (LCM, OTC, TS, and VLM) were detected.

78 FR 52607 - Unified Registration System

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-23

...'' and click ``Search.'' Next, click ``Open Docket Folder'' in the ``Actions'' column. Finally, in the... comments received are posted without change to http://www.regulations.gov . Anyone is able to search the... License CFR Code of Federal Regulations CMV Commercial Motor Vehicle CR Compliance Review CSA Compliance...

Automated Hydrophobic Interaction Chromatography Column Selection for Use in Protein Purification

PubMed Central

Murphy, Patrick J. M.; Stone, Orrin J.; Anderson, Michelle E.

2011-01-01

In contrast to other chromatographic methods for purifying proteins (e.g. gel filtration, affinity, and ion exchange), hydrophobic interaction chromatography (HIC) commonly requires experimental determination (referred to as screening or "scouting") in order to select the most suitable chromatographic medium for purifying a given protein 1. The method presented here describes an automated approach to scouting for an optimal HIC media to be used in protein purification. HIC separates proteins and other biomolecules from a crude lysate based on differences in hydrophobicity. Similar to affinity chromatography (AC) and ion exchange chromatography (IEX), HIC is capable of concentrating the protein of interest as it progresses through the chromatographic process. Proteins best suited for purification by HIC include those with hydrophobic surface regions and able to withstand exposure to salt concentrations in excess of 2 M ammonium sulfate ((NH4)2SO4). HIC is often chosen as a purification method for proteins lacking an affinity tag, and thus unsuitable for AC, and when IEX fails to provide adequate purification. Hydrophobic moieties on the protein surface temporarily bind to a nonpolar ligand coupled to an inert, immobile matrix. The interaction between protein and ligand are highly dependent on the salt concentration of the buffer flowing through the chromatography column, with high ionic concentrations strengthening the protein-ligand interaction and making the protein immobile (i.e. bound inside the column) 2. As salt concentrations decrease, the protein-ligand interaction dissipates, the protein again becomes mobile and elutes from the column. Several HIC media are commercially available in pre-packed columns, each containing one of several hydrophobic ligands (e.g. S-butyl, butyl, octyl, and phenyl) cross-linked at varying densities to agarose beads of a specific diameter 3. Automated column scouting allows for an efficient approach for determining which HIC media should be employed for future, more exhaustive optimization experiments and protein purification runs 4. The specific protein being purified here is recombinant green fluorescent protein (GFP); however, the approach may be adapted for purifying other proteins with one or more hydrophobic surface regions. GFP serves as a useful model protein, due to its stability, unique light absorbance peak at 397 nm, and fluorescence when exposed to UV light 5. Bacterial lysate containing wild type GFP was prepared in a high-salt buffer, loaded into a Bio-Rad DuoFlow medium pressure liquid chromatography system, and adsorbed to HiTrap HIC columns containing different HIC media. The protein was eluted from the columns and analyzed by in-line and post-run detection methods. Buffer blending, dynamic sample loop injection, sequential column selection, multi-wavelength analysis, and split fraction eluate collection increased the functionality of the system and reproducibility of the experimental approach. PMID:21968976

Technical Note: Detection of gas bubble leakage via correlation of water column multibeam images

NASA Astrophysics Data System (ADS)

Schneider von Deimling, J.; Papenberg, C.

2011-07-01

Hydroacoustic detection of natural gas release from the seafloor has been conducted in the past by using singlebeam echosounders. In contrast modern multibeam swath mapping systems allow much wider coverage, higher resolution, and offer 3-D spatial correlation. However, up to the present, the extremely high data rate hampers water column backscatter investigations. More sophisticated visualization and processing techniques for water column backscatter analysis are still under development. We here present such water column backscattering data gathered with a 50 kHz prototype multibeam system. Water column backscattering data is presented in videoframes grabbed over 75 s and a "re-sorted" singlebeam presentation. Thus individual gas bubbles rising from the 24 m deep seafloor clearly emerge in the acoustic images and rise velocities can be determined. A sophisticated processing scheme is introduced to identify those rising gas bubbles in the hydroacoustic data. It applies a cross-correlation technique similar to that used in Particle Imaging Velocimetry (PIV) to the acoustic backscatter images. Tempo-spatial drift patterns of the bubbles are assessed and match very well measured and theoretical rise patterns. The application of this processing scheme to our field data gives impressive results with respect to unambiguous bubble detection and remote bubble rise velocimetry. The method can identify and exclude the main driver for misinterpretations, i.e. fish-mediated echoes. Even though image-based cross-correlation techniques are well known in the field of fluid mechanics for high resolution and non-inversive current flow field analysis, this technique was never applied in the proposed sense for an acoustic bubble detector.

Determination of Amino Acids in Cell Culture and Fermentation Broth Media Using Anion-Exchange Chromatography with Integrated Pulsed Amperometric Detection

PubMed Central

Hanko, Valoran P.; Heckenberg, Andrea; Rohrer, Jeffrey S.

2004-01-01

Anion-exchange chromatography with integrated pulsed amperometric detection (AE-IPAD) separates and directly detects amino acids, carbohydrates, alditols, and glycols in the same injection without pre- or post-column derivatization. These separations use a combination of NaOH and NaOH/sodium acetate eluents. We previously published the successful use of this technique, also known as AAA-Direct, to determine free amino acids in cell culture and fermentation broth media. We showed that retention of carbohydrates varies with eluent NaOH concentration differently than amino acids, and thus separations can be optimized by varying the initial NaOH concentration and its duration. Unfortunately, some amino acids eluting in the acetate gradient portion of the method were not completely resolved from system-related peaks and from unknown peaks in complex cell culture and fermentation media. In this article, we present changes in method that improve amino acid resolution and system ruggedness. The success of these changes and their compatibility with the separations previously designed for fermentation and cell culture are demonstrated with yeast extract-peptone-dextrose broth, M199, Dulbecco’s modified Eagle’s (with F-12), L-15 (Leibovitz), and McCoy’s 5A cell culture media. PMID:15585828

Integrating a post-column makeup pump into preparative supercritical fluid chromatography systems to address stability and recovery issues during purifications.

PubMed

Bajpai, Lakshmikant; Naidu, Harshavardhan; Asokan, Kathiravan; Shaik, Khaja Mohiddin; Kaspady, Mahammed; Arunachalam, Piramanayagam; Wu, Dauh-Rurng; Mathur, Arvind; Sarabu, Ramakanth

2017-08-18

Purification of many pharmaceutical compounds by supercritical fluid chromatography (SFC) has always been challenging because of degradation of compound during the isolation step in the presence of acidic or basic modifiers in the mobile phase. Stability of such acid or base-sensitive compounds could be improved by post-column addition of a solvent containing base or acid modifier as counter ion through a make-up pump respectively to neutralize the compound fraction without affecting the resolution. One such case study has been presented in this work where the stability of a base-sensitive compound was addressed by the addition of acidic co-solvent through the make-up pump. Details of this setup and the investigation of degradation of the in-house base-sensitive compound are discussed in this paper. In addition, poor retentivity and low recovery of many non-polar compounds in SFC eluting under low co-solvent percentage is another major concern. Even though the desired separation could be achieved with low percentage of co-solvent, it's difficult to get the proper recovery after purification due to precipitation of the sample and significant aerosol formation inside the cyclone. We have demonstrated the first-time use of a post-column make-up pump on SFC 350 system to introduce additional solvent prior to cyclone to avoid the precipitation, reduce the aerosol formation and thus improve the recovery of non-polar compounds eluting under less than 10% of co-solvent. Copyright © 2017 Elsevier B.V. All rights reserved.

High-performance liquid chromatography coupled with post-column dual-bioactivity assay for simultaneous screening of xanthine oxidase inhibitors and free radical scavengers from complex mixture.

PubMed

Li, D Q; Zhao, J; Li, S P

2014-06-06

Xanthine oxidase (XO) can catalyze hypoxanthine and xanthine to generate uric acid and reactive oxygen species (ROS), including superoxide anion radical (O₂(•-)) and hydrogen peroxide. XO inhibitors and free radical scavengers are beneficial to the treatment of gout and many related diseases. In the present study, an on-line high-performance liquid chromatography (HPLC) coupled with post-column dual-bioactivity assay was established and successfully applied to simultaneously screening of XO inhibitors and free radical scavengers from a complex mixture, Oroxylum indicum extract. The integrated system of HPLC separation, bioactivity screening and mass spectrometry identification was proved to be simple and effective for rapid and sensitive screening of individual bioactive compounds in complex mixtures. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of citrus limonoid glucosides by high performance liquid chromatography coupled to post-column reaction with Ehrlich’s Reagent

USDA-ARS?s Scientific Manuscript database

A method for the identification and quantification of citrus limonoid glucosides in juices based upon high performance liquid chromatography (HPLC) separation coupled to post-column reaction with Ehrlichs’s reagent has been developed. This method utilizes a phenyl stationary phase and an isocratic ...

Water quality monitoring of Jialing-River in Chongqing using advanced ion chromatographic system.

PubMed

Tanaka, Kazuhiko; Shi, Chao-Hong; Nakagoshi, Nobukazu

2012-04-01

The water quality monitoring operation to evaluate the water quality of polluted river is an extremely important task for the river-watershed management/control based on the environmental policy. In this study, the novel, simple and convenient water quality monitoring of Jialing-River in Chongqing, China was carried out using an advanced ion chromatography (IC) consisting of ion-exclusion/cation-exchange chromatography (IEC/CEC) with conductivity detection for determining simultaneously the common anions such as SO4(2-), Cl(-), and NO3(-) and the cations such as Na+, NH4+, K+, Mg2+, and Ca2+, the ion-exclusion chromatography (IEC) with visible detection for determining simultaneously the nutrient components such as phosphate and silicate ions, and the IEC with the enhanced conductivity detection using a post column of K+-form cation-exchange resin for determining HCO3(-)-alkalinity as an inorganic-carbon source for biomass synthesis in biological reaction process under the aerobic conditions. According to the ionic balance theory between the total equivalent concentrations of anions and cations, the water quality evaluation of the Jialing-River waters taking at different sampling sites in Chongqing metropolitan area was carried out using the advanced IC system. As a result, the effectiveness of this novel water quality monitoring methodology using the IC system was demonstrated on the several practical applications to a typical biological sewage treatment plant on Jialing-River of Chongqing.

Simple determination of betaine, l-carnitine and choline in human urine using self-packed column and column-switching ion chromatography with nonsuppressed conductivity detection.

PubMed

Wei, Dan; Zhu, Yan; Guo, Ming

2018-02-01

A sequential online extraction, clean-up and separation system for the determination of betaine, l-carnitine and choline in human urine using column-switching ion chromatography with nonsuppressed conductivity detection was developed in this work. A self-packed pretreatment column (50 × 4.6 mm, i.d.) was used for the extraction and clean-up of betaine, l-carnitine and choline. The separation was achieved using self-packed cationic exchange column (150 × 4.6 mm, i.d.), followed by nonsuppressed conductivity detection. Under optimized experimental conditions, the developed method presented good analytical performance, with excellent linearity in the range of 0.60-100 μg mL -1 for betaine, 0.75-100 μg mL -1 for l-carnitine and 0.50-100 μg mL -1 for choline, with all correlation coefficients (R 2 ) >0.99 in urine. The limits of detection were 0.15 μg mL -1 for betaine, 0.20 μg mL -1 for l-carnitine and 0.09 μg mL -1 for choline. The intra- and inter-day accuracy and precision for all quality controls were within ±10.32 and ±9.05%, respectively. Satisfactory recovery was observed between 92.8 and 102.0%. The validated method was successfully applied to the detection of urinary samples from 10 healthy people. The values detected in human urine using the proposed method showed good agreement with the measurement reported previously. Copyright © 2017 John Wiley & Sons, Ltd.

Comparison of Rotavirus and Norovirus transport in standardised and natural soil-water systems

NASA Astrophysics Data System (ADS)

Gamazo, P. A.; Schijven, J. F.; Victoria, M.; Alvareda, E.; Lopez, F.; Ramos, J.; Lizasoain, A.; Sapriza-Azuri, G.; Castells, M.; Colina, R.

2016-12-01

Rotavirus and Norovirus are waterborne viruses that are major causes of diarrhea and others symptoms of acute gastroenteritis. An important pathway of these viruses is groundwater. In Uruguay, as in many developed and developing countries, there are areas where the only source of water for human consumption is groundwater. In the rural area of the Salto district, groundwater is commonly used without any treatment, as it is traditionally considered as a safe source. However, virus contamination have been detected in several wells in the area. The most probable source of contamination are nearby septic systems, since the sewer coverage is scarce. This work aims to evaluate and compare the virus transport processes for a standardised soil-water systems and for the Salto aquifer system. For this, the transport of Rotavirus and Norovirus from clinic samples was studied in two sets of column experiments: 6.7 cm columns with quartz sand under saturated conditions (ionic strength 1mM, pH 7.0) and with sand from the Salto aquifer (Uruguay) (9,2% coarse sand, 47,8% medium sand, 40,5% fine sand, magnesium/calcium bicarbonate water, Ionic strength 15.1 mM, pH 7.2). Both viruses were seeded for 2 pore volumes on the columns. Samples were collected at the column outlet and viruses were enumerated by Q-PRCR. Breakthrough curves were constructed and fitted to a two-site kinetic attachment/detachment model, including blocking using Hydrus-1D. In the quartz sand column, both Rotavirus and Norovirus were removed two orders in magnitude. In the Salto sand column, Rotavirus was removed 2 log10 as well, but Norovirus was removed 4 log10. The fitting of the breakthrough curves indicated that blocking played a role for Rotavirus in the Salto sand column. These results are consistent with field observation where only Rotavirus was detected in the Salto aquifer, while similar concentrations in Salto sewer effluent was measured for these two viruses. This work, besides reporting actual parameters values for human virus transport modelling, shows the significant differences in transport that human viruses can have in standardised and natural soil-water systems.

Using Gas Phase Reactions of Hexamethylene Triperoxide Diamine (HMTD) to Improve Detection in Mass Spectrometry

NASA Astrophysics Data System (ADS)

Colizza, Kevin; Yevdokimov, Alexander; McLennan, Lindsay; Smith, James L.; Oxley, Jimmie C.

2018-01-01

Our efforts to lower the detection limits of hexamethylene triperoxide diamine (HMTD) have uncovered previously unreported gas-phase reactions of primary and secondary amines with one of the six methylene carbons. The reaction occurs primarily in the atmospheric pressure chemical ionization (APCI) source and is similar to the behavior of alcohols with HMTD [1]. However, unlike alcohols, the amine reaction conserves the hydrogen peroxide on the intact product. Furthermore, with or without amines, HMTD is oxidized to tetramethylene diperoxide diamine dialdehyde (TMDDD) in a temperature-dependent fashion in the APCI source. Synthesized TMDDD forms very strong adducts (not products) to ammonium and amine ions in the electrospray ionization (ESI) source. Attempts to improve HMTD detection by generating TMDDD in the APCI source with post-column addition of amines were not successful. Signal intensity of the solvent related HMTD product in methanol, [HMTD+MeOH2-H2O2]+ (m/z 207.0975), was understandably related to the amount of methanol in the HMTD environment as it elutes into the source. With conditions optimized for this product, the detection of 100 pg on column was accomplished with a robust analysis of 300 pg (1.44 pmol) routinely performed on the Orbitrap mass spectrometers. [Figure not available: see fulltext.

[Synchronous extraction and determination of phenoxy acid herbicides in water by on-line monolithic solid phase microextraction-high performance liquid chromatography].

PubMed

Wang, Jiabin; Wu, Fangling; Zhao, Qi

2015-08-01

A C18 monolithic capillary column was utilized as the solid phase microextraction column to construct an in-tube SPME-HPLC system which was used to simultaneously extract and detect five phenoxy acid herbicides, including 2,4-dichlorophenoxyacetic acid (2,4-D), 2- (2-chloro)-phenoxy propionic acid (2,2-CPPA), 2-(3-chloro)-phenoxy propionic acid (2,3- CPPA), phenoxy propionic acid (PPA) and 2-(2,4-dichlorophenoxy) propionic acid (2,4-DP). The operating parameters of the in-tube SPME-HPLC system, including the length of the monolithic column, the sampling flow rate, the sampling time, the elution flow rate and the elution time, had been investigated in detail. The optimized operating parameters of the in-tube SPME-HPLC system were as follow: the length of the monolithic column was 20 cm, the sampling flow rate was 0. 04 mL/min, sampling time was 13 min; the elution flow rate was 0.02 mL/min, elution time was 5 min. Under the optimized conditions, the detection limits of the five phenoxy acid herbicides were as follows: 9 µg/L for PPA, 4 µg/L for 2,2-CPPA, 4 µg/L for 2,3-CPPA, 5 µg/L for 2,4-D, 5 µg/L for 2,4-DP. Compared with the HPLC method with direct injection, the combined system showed a good enrichment factors to the analytes. The recoveries of the five phenoxy acid herbicides were between 79.0% and 98.0% (RSD ≤ 3.9%). This method was successfully used to detect the five phenoxy acid herbicides in water samples with satisfactory results.

Seep Detection using E/V Nautilus Integrated Seafloor Mapping and Remotely Operated Vehicles on the United States West Coast

NASA Astrophysics Data System (ADS)

Gee, L. J.; Raineault, N.; Kane, R.; Saunders, M.; Heffron, E.; Embley, R. W.; Merle, S. G.

2017-12-01

Exploration Vessel (E/V) Nautilus has been mapping the seafloor off the west coast of the United States, from Washington to California, for the past three years with a Kongsberg EM302 multibeam sonar. This system simultaneously collects bathymetry, seafloor and water column backscatter data, allowing an integrated approach to mapping to more completely characterize a region, and has identified over 1,000 seafloor seeps. Hydrographic multibeam sonars like the EM302 were designed for mapping the bathymetry. It is only in the last decade that major mapping projects included an integrated approach that utilizes the seabed and water column backscatter information in addition to the bathymetry. Nautilus mapping in the Eastern Pacific over the past three years has included a number of seep-specific expeditions, and utilized and adapted the preliminary mapping guidelines that have emerged from research. The likelihood of seep detection is affected by many factors: the environment: seabed geomorphology, surficial sediment, seep location/depth, regional oceanography and biology, the nature of the seeps themselves: size variation, varying flux, depth, and transience, the detection system: design of hydrographic multibeam sonars limits use for water column detection, the platform: variations in the vessel and operations such as noise, speed, and swath overlap. Nautilus integrated seafloor mapping provided multiple indicators of seep locations, but it remains difficult to assess the probability of seep detection. Even when seeps were detected, they have not always been located during ROV dives. However, the presence of associated features (methane hydrate and bacterial mats) serve as evidence of potential seep activity and reinforce the transient nature of the seeps. Not detecting a seep in the water column data does not necessarily indicate that there is not a seep at a given location, but with multiple passes over an area and by the use of other contextual data, an area may be classified as likely or unlikely to host seeps.

A thermal biosensor based on enzyme reaction.

PubMed

Zheng, Yi-Hua; Hua, Tse-Chao; Xu, Fei

2005-01-01

Application of the thermal biosensor as analytical tool is promising due to advantages as universal, simplicity and quick response. A novel thermal biosensor based on enzyme reaction has been developed. This biosensor is a flow injection analysis system and consists of two channels with enzyme reaction column and reference column. The reference column, which is set for eliminating the unspecific heat, is inactived on special enzyme reaction of the ingredient to be detected. The special enzyme reaction takes places in the enzyme reaction column at a constant temperature realizing by a thermoelectric thermostat. Thermal sensor based on the thermoelectric module containing 127 serial BiTe-thermocouples is used to monitor the temperature difference between two streams from the enzyme reaction column and the reference column. The analytical example for dichlorvos shows that this biosensor can be used as analytical tool in medicine and biology.

On the radiation beaming of bright X-ray pulsars and constraints on neutron star mass-radius relation

NASA Astrophysics Data System (ADS)

Mushtukov, Alexander A.; Verhagen, Patrick A.; Tsygankov, Sergey S.; van der Klis, Michiel; Lutovinov, Alexander A.; Larchenkova, Tatiana I.

2018-03-01

The luminosity of accreting magnetized neutron stars can largely exceed the Eddington value due to appearance of accretion columns. The height of the columns can be comparable to the neutron star radius. The columns produce the X-rays detected by the observer directly and illuminate the stellar surface, which reprocesses the X-rays and causes additional component of the observed flux. The geometry of the column and the illuminated part of the surface determine the radiation beaming. Curved space-time affects the angular flux distribution. We construct a simple model of the beam patterns formed by direct and reflected flux from the column. We take into account the possibility of appearance of accretion columns, whose height is comparable to the neutron star radius. We argue that depending on the compactness of the star, the flux from the column can be either strongly amplified due to gravitational lensing, or significantly reduced due to column eclipse by the star. The eclipses of high accretion columns result in specific features in pulse profiles. Their detection can put constraints on the neutron star radius. We speculate that column eclipses are observed in X-ray pulsar V 0332+53, leading us to the conclusion of large neutron star radius in this system (˜15 km if M ˜ 1.4 M⊙). We point out that the beam pattern can be strongly affected by scattering in the accretion channel at high luminosity, which has to be taken into account in the models reproducing the pulse profiles.

Analysis of 6-mercaptopurine in human plasma with a high-performance liquid chromatographic method including post-column derivatization and fluorimetric detection.

PubMed

Jonkers, R E; Oosterhuis, B; ten Berge, R J; van Boxtel, C J

1982-12-10

A relatively simple assay with improved reliability and sensitivity for measuring levels of 6-mercaptopurine in human plasma is presented. After extraction of the compound and the added internal standard with phenyl mercury acetate, samples were separated by ion-pair reversed-phase high-performance liquid chromatography. On-line the analytes were oxidized to fluorescent products and detected in a flow-fluorimeter. The within-day coefficient of variation was 3.8% at a concentration of 25 ng/ml. The lower detection limit was 2 ng/ml when 1.0 ml of plasma was used. Mercaptopurine concentration versus time curves of two subjects after a single oral dose of azathioprine are shown.

Airborne 2-Micron Double-Pulsed Integrated Path Differential Absorption Lidar for Column CO2 Measurement

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Refaat, Tamer F.; Remus, Ruben G.; Fay, James J.; Reithmaier, Karl

2014-01-01

Double-pulse 2-micron lasers have been demonstrated with energy as high as 600 millijouls and up to 10 Hz repetition rate. The two laser pulses are separated by 200 microseconds and can be tuned and locked separately. Applying double-pulse laser in DIAL system enhances the CO2 measurement capability by increasing the overlap of the sampled volume between the on-line and off-line. To avoid detection complicity, integrated path differential absorption (IPDA) lidar provides higher signal-to-noise ratio measurement compared to conventional range-resolved DIAL. Rather than weak atmospheric scattering returns, IPDA rely on the much stronger hard target returns that is best suited for airborne platforms. In addition, the IPDA technique measures the total integrated column content from the instrument to the hard target but with weighting that can be tuned by the transmitter. Therefore, the transmitter could be tuned to weight the column measurement to the surface for optimum CO2 interaction studies or up to the free troposphere for optimum transport studies. Currently, NASA LaRC is developing and integrating a double-Pulsed 2-micron direct detection IPDA lidar for CO2 column measurement from an airborne platform. The presentation will describe the development of the 2-micron IPDA lidar system and present the airborne measurement of column CO2 and will compare to in-situ measurement for various ground target of different reflectivity.

NASA combined file postings statistics based on NASA Thesaurus, January 1968 - January 1991

NASA Technical Reports Server (NTRS)

1991-01-01

The NASA Combined File Postings Statistics is published semiannually (January and July). This alphabetical listing of postable subject terms contained in the NASA Thesaurus is used to display the number of postings (documents) indexed by each subject term from 1968 to data. The postings totals per term are separated by announcement or other media into STAR, IAA, NLN, and OTHER columnar entries covering the NASA document collection (1968 to date). Over 595,000 book postings for NALNET Books held by NASA Libraries are included under the NLN column. CSTAR postings as well as some previously unreported series are listed under the 'other' column. The distribution of 18,748,083 postings among the 17,304 Thesaurus terms is tabulated on the last page of Combined File Postings Statistics.

Effectiveness of a computer-aided neuroanatomy program for entry-level physical therapy students: anatomy and clinical examination of the dorsal column-medial lemniscal system.

PubMed

McKeough, D Michael; Mattern-Baxter, Katrin; Barakatt, Edward

2010-01-01

The purpose of this study was to determine if a computer-aided instruction learning module improves students' knowledge of the neuroanatomy/physiology and clinical examination of the dorsal column-medial lemniscal (DCML) system. Sixty-one physical therapy students enrolled in a clinical neurology course in entry-level PT educational programs at two universities participated in the study. Students from University-1 (U1;) had not had a previous neuroanatomy course, while students from University-2 (U2;) had taken a neuroanatomy course in the previous semester. Before and after working with the learning module, students took a paper-and-pencil test on the neuroanatomy/physiology and clinical examination of the DCML system. Kruskal-Wallis one-way ANOVA and Mann-Whitney tests were used to determine if differences existed between neuroanatomy/physiology examination scores and clinical examination scores before and after taking the learning module, and between student groups based on university attended. For students from U1, neuroanatomy/physiology post-test scores improved significantly over pre-test scores (p < 0.001), while post-test scores of students from U2 did not (p = 0.60). Neuroanatomy/physiology pre-test scores from U2 were significantly better than those from U1 (p < 0.001); there was no significant difference in post-test scores (p = 0.062). Clinical examination pre-test and post-test scores from U2 were significantly better than those from U1 (p < 0.001). Clinical examination post-test scores improved significantly from the pre-test scores for both U1 (p < 0.001) and U2 (p < 0.001).

Spot restoration for GPR image post-processing

DOEpatents

Paglieroni, David W; Beer, N. Reginald

2014-05-20

A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

Semiconductor radiation detector

DOEpatents

Bell, Zane W.; Burger, Arnold

2010-03-30

A semiconductor detector for ionizing electromagnetic radiation, neutrons, and energetic charged particles. The detecting element is comprised of a compound having the composition I-III-VI.sub.2 or II-IV-V.sub.2 where the "I" component is from column 1A or 1B of the periodic table, the "II" component is from column 2B, the "III" component is from column 3A, the "IV" component is from column 4A, the "V" component is from column 5A, and the "VI" component is from column 6A. The detecting element detects ionizing radiation by generating a signal proportional to the energy deposited in the element, and detects neutrons by virtue of the ionizing radiation emitted by one or more of the constituent materials subsequent to capture. The detector may contain more than one neutron-sensitive component.

Measurement of H2S in Crude Oil and Crude Oil Headspace Using Multidimensional Gas Chromatography, Deans Switching and Sulfur-selective Detection

PubMed Central

Heshka, Nicole E.; Hager, Darcy B.

2015-01-01

A method for the analysis of dissolved hydrogen sulfide in crude oil samples is demonstrated using gas chromatography. In order to effectively eliminate interferences, a two dimensional column configuration is used, with a Deans switch employed to transfer hydrogen sulfide from the first to the second column (heart-cutting). Liquid crude samples are first separated on a dimethylpolysiloxane column, and light gases are heart-cut and further separated on a bonded porous layer open tubular (PLOT) column that is able to separate hydrogen sulfide from other light sulfur species. Hydrogen sulfide is then detected with a sulfur chemiluminescence detector, adding an additional layer of selectivity. Following separation and detection of hydrogen sulfide, the system is backflushed to remove the high-boiling hydrocarbons present in the crude samples and to preserve chromatographic integrity. Dissolved hydrogen sulfide has been quantified in liquid samples from 1.1 to 500 ppm, demonstrating wide applicability to a range of samples. The method has also been successfully applied for the analysis of gas samples from crude oil headspace and process gas bags, with measurement from 0.7 to 9,700 ppm hydrogen sulfide. PMID:26709594

Preliminary post-emplacement safety analysis of the subseabed disposal of high-level nuclear waste

NASA Astrophysics Data System (ADS)

Kaplan, M. F.; Koplik, C. M.; Klett, R. D.

1984-09-01

The radiological hazard from the disposal of high-level nuclear waste within the deep ocean sediments is evaluated, on a preliminary basis, for locations in the central North Pacific and in the northwestern Atlantic. Radio-nuclide transport in the sediment and water column and by marine organisms is considered. Peak doses to an individual are approximately five orders of magnitude below background levels for both sites. Sensitivity analyses for most aspects of the post-emplacement systems models are included.

Separation of actinides using capillary extraction chromatography-inductively coupled plasma mass spectrometry.

PubMed

Peterson, Dominic S; Montoya, Velma M

2009-08-01

Trace levels of actinides have been separated on capillary extraction chromatography columns. Detection of the actinides was achieved using an inductively coupled plasma mass spectrometer, which was coupled with the extraction chromatography system. In this study, we compare 30-cm long, 4.6 mm i.d. columns to capillary columns (750 microm i.d.) with lengths from 30 cm up to 150 cm. The columns that were tested were packed with TRU resin. We were able to separate a mixture of five actinides ((232)Th, (238)U, (237)Np, (239)Pu, and (241)Am). This work has application to rapid bioassay as well as automated separations of actinide materials.

High-field fMRI unveils orientation columns in humans.

PubMed

Yacoub, Essa; Harel, Noam; Ugurbil, Kâmil

2008-07-29

Functional (f)MRI has revolutionized the field of human brain research. fMRI can noninvasively map the spatial architecture of brain function via localized increases in blood flow after sensory or cognitive stimulation. Recent advances in fMRI have led to enhanced sensitivity and spatial accuracy of the measured signals, indicating the possibility of detecting small neuronal ensembles that constitute fundamental computational units in the brain, such as cortical columns. Orientation columns in visual cortex are perhaps the best known example of such a functional organization in the brain. They cannot be discerned via anatomical characteristics, as with ocular dominance columns. Instead, the elucidation of their organization requires functional imaging methods. However, because of insufficient sensitivity, spatial accuracy, and image resolution of the available mapping techniques, thus far, they have not been detected in humans. Here, we demonstrate, by using high-field (7-T) fMRI, the existence and spatial features of orientation- selective columns in humans. Striking similarities were found with the known spatial features of these columns in monkeys. In addition, we found that a larger number of orientation columns are devoted to processing orientations around 90 degrees (vertical stimuli with horizontal motion), whereas relatively similar fMRI signal changes were observed across any given active column. With the current proliferation of high-field MRI systems and constant evolution of fMRI techniques, this study heralds the exciting prospect of exploring unmapped and/or unknown columnar level functional organizations in the human brain.

Pesticide dissipation and microbial community changes in a biopurification system: influence of the rhizosphere.

PubMed

Diez, M C; Elgueta, S; Rubilar, O; Tortella, G R; Schalchli, H; Bornhardt, C; Gallardo, F

2017-12-01

The dissipation of atrazine, chlorpyrifos and iprodione in a biopurification system and changes in the microbial and some biological parameters influenced by the rhizosphere of Lolium perenne were studied in a column system packed with an organic biomixture. Three column depths were analyzed for residual pesticides, peroxidase, fluorescein diacetate activity and microbial communities. Fungal colonization was analyzed by confocal laser scanning microscopy to assess the extent of its proliferation in wheat straw. The L. perenne rhizosphere enhanced pesticide dissipation and negligible pesticide residues were detected at 20-30 cm column depth. Atrazine, chlorpyrifos and iprodione removal was 82, 89 and 74% respectively in the first 10 cm depth for columns with vegetal cover. The presence of L. perenne in contaminated columns stimulated peroxidase activity in all three column depth sections. Fluorescein diacetate activity decreased over time in all column sections with the highest values in biomixtures with vegetal cover. Microbial communities, analyzed by PCR-DGGE, were not affected by the pesticide mixture application, presenting high values of similarity (>65%) with and without vegetal cover. Microbial abundance of Actinobacteria varied according to treatment and no clear link was observed. However, bacterial abundance increased over time and was similar with and without vegetal cover. On the other hand, fungal abundance decreased in all sections of columns after 40 days, but an increase was observed in response to pesticide application. Fungal colonization and straw degradation during pesticide dissipation were verified by monitoring the lignin autofluorescence loss.

Tuning a Parallel Segmented Flow Column and Enabling Multiplexed Detection.

PubMed

Pravadali-Cekic, Sercan; Kocic, Danijela; Hua, Stanley; Jones, Andrew; Dennis, Gary R; Shalliker, R Andrew

2015-12-15

Active flow technology (AFT) is new form of column technology that was designed to overcome flow heterogeneity to increase separation performance in terms of efficiency and sensitivity and to enable multiplexed detection. This form of AFT uses a parallel segmented flow (PSF) column. A PSF column outlet end-fitting consists of 2 or 4 ports, which can be multiplexed to connect up to 4 detectors. The PSF column not only allows a platform for multiplexed detection but also the combination of both destructive and non-destructive detectors, without additional dead volume tubing, simultaneously. The amount of flow through each port can also be adjusted through pressure management to suit the requirements of a specific detector(s). To achieve multiplexed detection using a PSF column there are a number of parameters which can be controlled to ensure optimal separation performance and quality of results; that is tube dimensions for each port, choice of port for each type of detector and flow adjustment. This protocol is intended to show how to use and tune a PSF column functioning in a multiplexed mode of detection.

40 CFR 141.131 - Analytical requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... chromatography 300.1 D 6581-00 Ion chromatography & post column reaction 317.0 Rev 2.0 6, 326.0 6 IC/ICP-MS 321.8... sample collection. 6 Ion chromatography & post column reaction or IC/ICP-MS must be used for monitoring... study between a maximum and minimum acceptance limit of ±50% and ±15% of the study mean. (iii) Beginning...

The Application of TD/GC/NICI-MS with an Al2O3-PLOT-S Column for the Determination of Perfluoroalkylcycloalkanes in the Atmosphere.

PubMed

Ren, Yu; Schlager, Hans; Martin, Damien

2014-01-01

A modified method for the quantitative determination of atmospheric perfluoroalkylcycloalkanes (PFCs) using thermal desorption coupled with gas chromatography and detection by negative ion chemical ionization-mass spectrometry was developed. Using an optimized analytical system, a commercially available Al 2 O 3 porous layer open tubular (PLOT) capillary column (30 m × 0.25 mm) deactivated with Na 2 SO 4 was used for separation of PFCs. Improvements in the separation of PFCs, the corresponding identification and the limit of detection of PFCs using this method and column are presented. The method was successfully applied to determine the atmospheric background concentrations of a range of PFCs from a number of samples collected at a rural site in Germany. The results of this study suggest that the method outlined using the Al 2 O 3 -PLOT-S capillary column has good sensitivity and selectivity, and that it can be deployed in a routine laboratory process for the analysis of PFCs in the future research work. In addition, the ability of this column to separate the isomers of one of the lower boiling PFCs (perfluorodimethylcyclobutane) and its ability to resolve perfluoroethylcyclohexane offer the opportunity for single-column analysis for multiple PFCs.

Leaching behaviour of azoxystrobin and metabolites in soil columns.

PubMed

Ghosh, Rakesh Kumar; Singh, Neera

2009-09-01

Azoxystrobin [methyl (E)-2-{2-[6-(2-cyanophenoxy)pyrimidin-4-yloxy]phenyl}-3-methoxyacrylate], a strobilurin fungicide, is a broad-spectrum, systemic and soil-applied fungicide. Azoxystrobin has been registered for rice cultivation in India, but no information is available on its leaching behaviour in Indian soils. Therefore, leaching behaviour of azoxystrobin was studied in packed and intact soil columns under different irrigation regimes. Azoxystrobin did not leach out of the 300 mm long columns after 126 and 362 mm rainfall. After percolating water equivalent to 362 mm rainfall, azoxystrobin leached down to 10-15 cm (packed columns) and 15-20 cm (intact columns) depth. Azoxystrobin was not detected in the leachate from the packed column leached with 94.5 mL water every week (140 mm rainfall per month) during the 28 weeks of the study period. However, azoxystrobin acid, formed by azoxystrobin degradation, was detected in the leachate after 18 weeks. At the end of the study, azoxystrobin had leached down to 5-10 cm depth, and only 60% of initially applied azoxystrobin was recovered from the soil. The results indicate that azoxystrobin is fairly immobile in sandy loam soil, but azoxystrobin acid, a major metabolite of azoxystrobin, is quite mobile and may pose a threat of soil and groundwater contamination. Copyright 2009 Society of Chemical Industry.

Simultaneous determination of byak-angelicin and oxypeucedanin hydrate in rat plasma by column-switching high-performance liquid chromatography with ultraviolet detection.

PubMed

Ishihara, K; Fukutake, M; Asano, T; Mizuhara, Y; Wakui, Y; Yanagisawa, T; Kamei, H; Ohmori, S; Kitada, M

2001-04-05

A simple and sensitive column-switching HPLC method was developed for the simultaneous determination of two furocoumarin compounds, byak-angelicin and oxypeucedanin hydrate, which are the main components of hot water extract of Angelica dahurica root (AE), in rat plasma. Plasma sample was simply deproteinated with perchloric acid. After centrifugation, the supernatant was injected into a column-switching HPLC system consisting of a clean-up column (Symmetry Shield RP 8, 20x3.9 mm I.D.) and analytical column (Symmetry C18, 75x4.6 mm I.D.) which were connected with a six-port switching valve. The flow-rate of the mobile phase (acetonitrile-water, 20:80) was maintained at 1 ml/min. Detection was carried out at wavelength 260 nm with a UV detector. The column temperature was maintained at 40 degrees C. The calibration curves of byak-angelicin and oxypeucedanin hydrate were linear over the ranges 19.6 to 980 ng/ml (r2>0.997). The accuracy of these analytes was less than 4.4%. The intra- and inter-day relative standard deviations of byak-angelicin and oxypeucedanin hydrate were within 12.0% and 12.7%, respectively. The present method was applied for the analysis of plasma concentration from rats after administration of AE.

HPLC column-switching technique for sample preparation and fluorescence determination of propranolol in urine using fused-core columns in both dimensions.

PubMed

Satínský, Dalibor; Havlíková, Lucie; Solich, Petr

2013-08-01

A new and fast high-performance liquid chromatography (HPLC) column-switching method using fused-core columns in both dimensions for sample preconcentration and determination of propranolol in human urine has been developed. On-line sample pretreatment and propranolol preconcentration were performed on an Ascentis Express RP-C-18 guard column (5 × 4.6 mm), particle size, 2.7 μm, with mobile phase acetonitrile/water (5:95, v/v) at a flow rate of 2.0 mL min(-1) and at a temperature of 50 °C. Valve switch from pretreatment column to analytical column was set at 4.0 min in a back-flush mode. Separation of propranolol from other endogenous urine compounds was achieved on the fused-core column Ascentis Express RP-Amide (100 × 4.6 mm), particle size, 2.7 μm, with mobile phase acetonitrile/water solution of 0.5% triethylamine, pH adjusted to 4.5 by means of glacial acetic acid (25:75, v/v), at a flow rate of 1.0 mL min(-1) and at a temperature of 50 °C. Fluorescence excitation/emission detection wavelengths were set at 229/338 nm. A volume of 1,500 μL of filtered urine sample solution was injected directly into the column-switching HPLC system. The total analysis time including on-line sample pretreatment was less than 8 min. The experimentally determined limit of detection of the method was found to be 0.015 ng mL(-1).

Optimization of a two-dimensional liquid chromatography-supercritical fluid chromatography-mass spectrometry (2D-LC-SFS-MS) system to assess "in-vivo" inter-conversion of chiral drug molecules.

PubMed

Goel, Meenakshi; Larson, Eli; Venkatramani, C J; Al-Sayah, Mohammad A

2018-05-01

Enantioselective analysis is an essential requirement during the pharmaceutical development of chiral drug molecules. In pre-clinical and clinical studies, the Food and Drug Administration (FDA) mandates the assessment of "in vivo" inter-conversion of chiral drugs to determine their physiological effects. In-vivo analysis of the active pharmaceutical ingredient (API) and its potential metabolites could be quite challenging due to their low abundance (ng/mL levels) and matrix interferences. Therefore, highly selective and sensitive analytical techniques are required to separate the API and its metabolites from the matrix components and one another. Additionally, for chiral APIs, further analytical separation is required to resolve the API and its potential metabolites from their corresponding enantiomers. In this work, we demonstrate the optimization of our previously designed two-dimensional liquid chromatography-supercritical fluid chromatography-mass spectrometry (2D-LC-SFC -MS) system to achieve 10 ng/mL detection limit [1]. The first LC dimension, used as a desalting step, could efficiently separate the API from its potential metabolites and matrix components. The API and its metabolites were then trapped/focused on small trapping columns and transferred onto the second SFC dimension for chiral separation. Detection can be achieved by ultra-violet (UV) or MS detection. Different system parameters such as column dimensions, transfer volumes, trapping column stationary phase, system tubing internal diameter (i.d.), and detection techniques, were optimized to enhance the sensitivity of the 2D-LC-SFC-MS system. The limit of detection was determined to be 10 ng/mL. An application is described where a mouse hepatocyte treated sample was analyzed using the optimized 2D-LC-SFC-MS system with successful assessment of the ratio of API to its metabolite (1D-LC), as well as the corresponding enantiomeric excess values (% e.e.) of each (2D-SFC). Copyright © 2018 Elsevier B.V. All rights reserved.

Spatially assisted down-track median filter for GPR image post-processing

DOEpatents

Paglieroni, David W; Beer, N Reginald

2014-10-07

A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

Simultaneous Analysis of Monovalent Anions and Cations with a Sub-Microliter Dead-Volume Flow-Through Potentiometric Detector for Ion Chromatography

PubMed Central

Dumanli, Rukiye; Attar, Azade; Erci, Vildan; Isildak, Ibrahim

2016-01-01

A microliter dead-volume flow-through cell as a potentiometric detector is described in this article for sensitive, selective and simultaneous detection of common monovalent anions and cations in single column ion chromatography for the first time. The detection cell consisted of less selective anion- and cation-selective composite membrane electrodes together with a solid-state composite matrix reference electrode. The simultaneous separation and sensitive detection of sodium (Na+), potassium (K+), ammonium (NH4+), chloride (Cl−) and nitrate (NO3−) in a single run was achieved by using 98% 1.5 mM MgSO4 and 2% acetonitrile eluent with a mixed-bed ion-exchange separation column without suppressor column system. The separation and simultaneous detection of the anions and cations were completed in 6 min at the eluent flow-rate of 0.8 mL/min. Detection limits, at S/N = 3, were ranged from 0.2 to 1.0 µM for the anions and 0.3 to 3.0 µM for the cations, respectively. The developed method was successfully applied to the simultaneous determination of monovalent anions and cations in several environmental and biological samples. PMID:26786906

Rapid chiral separation of atenolol, metoprolol, propranolol and the zwitterionic metoprolol acid using supercritical fluid chromatography-tandem mass spectrometry - Application to wetland microcosms.

PubMed

Svan, Alfred; Hedeland, Mikael; Arvidsson, Torbjörn; Jasper, Justin T; Sedlak, David L; Pettersson, Curt E

2015-08-28

A method for enantiomeric separation of the three β-blocking agents atenolol, metoprolol, propranolol and the zwitterionic metoprolol acid, a major metabolite of both metoprolol and in environmental matrices also atenolol, has been developed. By use of supercritical fluid chromatography and the polysaccharide-based Chiralpak(®) IB-3, all four compounds were simultaneously enantiomerically separated (Rs>1.5) within 8min. Detection was performed using tandem mass spectrometry, and to avoid isobaric interference between the co-eluting metoprolol and metoprolol acid, the achiral column Acquity(®) UPC(2) BEH 2-EP was attached ahead of to the chiral column. Carbon dioxide with 18% methanol containing 0.5% (v/v) of the additives trifluoroacetic acid and ammonia in a 2:1 molar ratio were used as mobile phase. A post column make-up flow (0.3mL/min) of methanol containing 0.1% (v/v) formic acid was used to enhance the positive electrospray ionization. Detection was carried out using a triple quadrupole mass spectrometer operating in the selected reaction monitoring mode, using one transition per analyte and internal standard. The method was successfully applied for monitoring the enantiomeric fraction change over time in a laboratory scale wetland degradation study. It showed good precision, recovery, sensitivity and low effect of the sample matrix. Copyright © 2015. Published by Elsevier B.V.

Aliphatic long chain quaternary ammonium compounds analysis by ion-pair chromatography coupled with suppressed conductivity and UV detection in lysing reagents for blood cell analysers.

PubMed

Giovannelli, D; Abballe, F

2005-08-26

A method has been developed which allows simultaneous determination of three linear alkyl trimethylammonium salts. Dodecyltrimethylammonium chloride, tetradecyltrimethylammonium bromide and hexadecyltrimethylammonium chloride are widely used as main active ingredients of lysing reagents for blood cell analyzers which perform white blood cells differential determination into two or more sub-populations by impedance analysis. The ion-pair on styrene-divinyl benzene chromatographic phase looks like a suitable, reliable and long term stable tool for separation of such quaternary compounds. The detection based on suppressed conductivity was chosen because of the lack of significance chromophores. A micromembrane suppressor device compatible with high solvent concentration (up to 80%) was used in order to minimize the conductivity background before the detection. In the present work we show how the chemical post column derivatization makes the alkyl chain detectable also by UV direct detection at 210 nm.

On the mechanical modeling of tensegrity columns subject to impact loading

NASA Astrophysics Data System (ADS)

Amendola, Ada; Favata, Antonino; Micheletti, Andrea

2018-04-01

A physical model of a tensegrity columns is additively manufactured in a titanium alloy. After removing sacrificial supports, such a model is post-tensioned through suitable insertion of Spectra cables. The wave dynamics of the examined system is first experimentally investigated by recording the motion through high-speed cameras assisted by a digital image correlation algorithm, which returns time-histories of the axial displacements of the bases of each prism of the column. Next, the experimental response is mechanically simulated by means of two different models: a stick-and-spring model accounting for the presence of bending-stiff connections between the 3D-printed elements (mixed bending-stretching response), and a tensegrity model accounting for a purely stretching response. The comparison of theory and experiment reveals that the presence of bending-stiff connections weakens the nonlinearity of the wave dynamics of the system. A stretching-dominated response instead supports highly compact solitary waves in the presence of small prestress and negligible bending stiffness of connections.

Adaption of Ehrlich’s Reagent to a HPLC post-column reaction system for the quantification of limonoid glucosides (abstract)

USDA-ARS?s Scientific Manuscript database

Citrus limonoid glucosides are found in large quantities in citrus fruits and seeds. Characterization and quantification of these compounds is important because they contribute to citrus quality and are reported to be biologically active. Unlike other bioactive compounds (e.g., flavonoids) present...

Monitoring of streptomycin and dihydrostreptomycin residual levels in porcine meat press juice and muscle via solid-phase fluorescence immunoassay and confirmatory analysis by liquid chromatography after post-column derivatization.

PubMed

Pyun, Chang-Won; Abd El-Aty, A M; Hashim, M M M; Shim, Jae-Han; Lee, Si-Kyung; Choi, Kang-Duk; Park, Kwan-Ha; Shin, Ho-Chul; Lee, Chiho

2008-03-01

A solid-phase fluorescence immunoassay (SPFIA) that was primarily developed for detection of antibiotic residues in milk was qualitatively applied for the pre-screening of the residues of aminoglycoside antibiotics, streptomycin and dihydrostreptomycin, in meat press juice. The confirmation of both analytes was performed using a validated method of highperformance liquid chromatography with post-column derivatization. The analytical performance was demonstrated by the analysis of pork meat samples spiked at three concentration levels, ranging from 0.25 to 2.5 ppm for each analyte. In general, the recoveries ranged from 80.4 to 81.5% and from 79.6 to 84.4% for streptomycin and dihydrostreptomycin, respectively, with relative standard deviations lower than 6%. The limits of detection were 0.1 and 0.15 ppm for streptomycin and dihydrostreptomycin, respectively, and the limits of quantification of 0.35 and 0.5 ppm are below the maximum residue limits of Codex, the European Union, and the Korean Food and Drug Administration (ranging from 0.5 to 0.6 ppm). Eight real samples collected from the Seoul area were first monitored using SPFIA, and none of them were found positive. These findings are in good accordance with those observed by HPLC analysis. To the best of our knowledge, this is the first report to monitor the aminoglycoside residues in pork meat press juice using SPFIA.

Evaluating Rotavirus and Norovirus transport processes in standardised and natural soil-water columns experiments

NASA Astrophysics Data System (ADS)

Gamazo, Pablo; Schijven, Jack; Victoria, Matias; Alvareda, Elena; López Tort, Fernando; Ramos, Julián; Lizasoain, Andrés; Sapriza, Gonzalo; Castells, Matias; Colina, Rodney

2017-04-01

In Uruguay, as in many developed and developing countries, rotavirus and norovirus are major causes of diarrhea and others symptoms of acute gastroenteritis. In some areas of Uruguay, groundwater is the only source of water for human consumption. In the rural area of the Salto district, virus contamination has been detected in several groundwater wells. Because sewer coverage is low, the most probable sources of contamination are nearby septic systems. This work aims to evaluate the transport of rotavirus and norovirus from clinic samples in two sets of column experiments under saturated conditions: 6.7-cm columns with quartz sand (ionic strength 1mM, pH 7.0) and with sand from the Salto aquifer (Uruguay) (9,2% coarse sand, 47,8% medium sand, 40,5% fine sand, magnesium/calcium bicarbonate water, Ionic strength 15.1 mM, pH 7.2). Both viruses were seeded for 2 pore volumes onto the columns. Samples were collected at the column outlet and viruses were enumerated by Q-PRCR. Breakthrough curves were constructed and fitted to a two-site kinetic attachment/detachment model, including blocking using Hydrus-1D. In the quartz sand column, both rotavirus and norovirus were removed two orders in magnitude. In the Salto sand column, rotavirus was removed 2 log10 as well, but norovirus was removed 4 log10. The fitting of the breakthrough curves indicated that blocking played a role for rotavirus in the Salto sand column. These results are consistent with the field observation where only rotavirus was detected in the Salto aquifer, while similar concentrations in Salto sewer effluent were measured for both viruses. This work, besides reporting actual parameters values for human virus transport modelling, shows the significant differences in transport that human viruses can have in standardised and natural soil-water systems.

Evaluation of a hydrophilic interaction liquid chromatography design space for sugars and sugar alcohols.

PubMed

Hetrick, Evan M; Kramer, Timothy T; Risley, Donald S

2017-03-17

Based on a column-screening exercise, a column ranking system was developed for sample mixtures containing any combination of 26 sugar and sugar alcohol analytes using 16 polar stationary phases in the HILIC mode with acetonitrile/water or acetone/water mobile phases. Each analyte was evaluated on the HILIC columns with gradient elution and the subsequent chromatography data was compiled into a statistical software package where any subset of the analytes can be selected and the columns are then ranked by the greatest separation. Since these analytes lack chromophores, aerosol-based detectors, including an evaporative light scattering detector (ELSD) and a charged aerosol detector (CAD) were employed for qualitative and quantitative detection. Example qualitative applications are provided to illustrate the practicality and efficiency of this HILIC column ranking. Furthermore, the design-space approach was used as a starting point for a quantitative method for the trace analysis of glucose in trehalose samples in a complex matrix. Knowledge gained from evaluating the design-space led to rapid development of a capable method as demonstrated through validation of the following parameters: specificity, accuracy, precision, linearity, limit of quantitation, limit of detection, and range. Copyright © 2017 Elsevier B.V. All rights reserved.

Nepem-211 ion exchange conductive membrane immobilized tris(2,2´-bipyridyl) ruthenium(II) electrogenerated chemiluminescence flow sensor for high-performance liquid chromatography and its application.

PubMed

Li, Yongbo; Zhang, Zhujun

2013-01-01

We developed a sensitive and robust electrogenerated chemiluminescence (ECL) flow sensor based on Ru(bpy)3(2+) immobilized with a Nepem-211 perfluorinated ion exchange conductance membrane, which has robustness and stability under a wide range of chemical and physical conditions, good electrical conductivity, isotropy and a high exchange capacity for immobilization of Ru(bpy)3(2+). The flow sensor has been used as a post-column detector in high-performance liquid chromatography for determination of erythromycin and clarithromycin in honey and pork, and tricyclic antidepressant drugs in human urine. Under optimal conditions, the linear ranges were 0.03-26 ng/μL and 0.01-1 ng/μL for macrolides and tricyclic antidepressant drugs, respectively. The detection limits were 0.02, 0.01, 0.01, 0.06 and 0.003 ng/μL for erythromycin, clarithromycin, doxepin, amitriptyline and clomipramine, respectively. There is no post-column reagent addition. In addition to the conservation expensive reagents, the experimental setup was simplified. The flow sensor was used for 2 years with high sensitivity and stability. Copyright © 2013 John Wiley & Sons, Ltd.

Renewable surface fluorescence sandwich immunoassay biosensor for rapid sensitive botulinum toxin detection in an automated fluidic format.

PubMed

Grate, Jay W; Warner, Marvin G; Ozanich, Richard M; Miller, Keith D; Colburn, Heather A; Dockendorff, Brian; Antolick, Kathryn C; Anheier, Norman C; Lind, Michael A; Lou, Jianlong; Marks, James D; Bruckner-Lea, Cynthia J

2009-05-01

A renewable surface biosensor for rapid detection of botulinum neurotoxin serotype A is described based on fluidic automation of a fluorescence sandwich immunoassay, using a recombinant protein fragment of the toxin heavy chain ( approximately 50 kDa) as a structurally valid simulant. Monoclonal antibodies AR4 and RAZ1 bind to separate non-overlapping epitopes of the full botulinum holotoxin ( approximately 150 kDa). Both of the targeted epitopes are located on the recombinant fragment. The AR4 antibody was covalently bound to Sepharose beads and used as the capture antibody. A rotating rod flow cell was used to capture these beads delivered as a suspension by a sequential injection flow system, creating a 3.6 microL column. After perfusing the bead column with sample and washing away the matrix, the column was perfused with Alexa 647 dye-labeled RAZ1 antibody as the reporter. Optical fibers coupled to the rotating rod flow cell at a 90 degrees angle to one another delivered excitation light from a HeNe laser (633 nm) using one fiber and collected fluorescent emission light for detection with the other. After each measurement, the used Sepharose beads are released and replaced with fresh beads. In a rapid screening approach to sample analysis, the toxin simulant was detected to concentrations of 10 pM in less than 20 minutes using this system.

Pre- and Post-Transfusion Alloimmunization in Dogs Characterized by 2 Antiglobulin-Enhanced Cross-match Tests.

PubMed

Goy-Thollot, I; Giger, U; Boisvineau, C; Perrin, R; Guidetti, M; Chaprier, B; Barthélemy, A; Pouzot-Nevoret, C; Canard, B

2017-09-01

When dogs are transfused, blood compatibility testing varies widely but may include dog erythrocyte antigen (DEA) 1 typing and rarely cross-matching. Prospective study to examine naturally occurring alloantibodies against red blood cells (RBCs) and alloimmunization by transfusion using 2 antiglobulin-enhanced cross-match tests. Eighty client-owned anemic, 72 donor, and 7 control dogs. All dogs were typed for DEA 1 and some also for DEA 4 and DEA 7. Major cross-match tests with canine antiglobulin-enhanced immunochromatographic strip and gel columns were performed 26-129 days post-transfusion (median, 39 days); some dogs had an additional early evaluation 11-22 days post-transfusion (median, 16 days). Plasma from alloimmunized recipients was cross-matched against RBCs from 34 donor and control dogs. The 2 cross-match methods gave entirely concordant results. All 126 pretransfusion cross-match results for the 80 anemic recipients were compatible, but 54 dogs died or were lost to follow up. Among the 26 recipients with follow-up, 1 dog accidently received DEA 1-mismatched blood and became cross-match-incompatible post-transfusion. Eleven of the 25 DEA 1-matched recipients (44%) became incompatible against other RBC antigens. No naturally occurring anti-DEA 7 alloantibodies were detected in DEA 7- dogs. The antiglobulin-enhanced immunochromatographic strip cross-match and laboratory gel column techniques identified no naturally occurring alloantibodies against RBC antigens, but a high degree of post-transfusion alloimmunization in dogs. Cross-matching is warranted in any dog that has been previously transfused independent of initial DEA 1 typing and cross-matching results before the first transfusion event. Copyright © 2017 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

Determination of aflatoxins and ochratoxin A in high-sugar-content traditional Turkish foods by affinity column cleanup and LC fluorescence detection.

PubMed

Senyuva, Hamide Z; Cimen, Dilek; Gilbert, John

2009-01-01

The effectiveness of an affinity column cleanup procedure followed by LC with fluorescence detection was established for the determination of aflatoxins and ochratoxin A in high-sugar-content traditional Turkish foods. Traditional foods, such as baklava (finely layered pastry filled with nuts and steeped in syrup), halvah (containing sesame paste and pistachios), cevizli sucuk (a confection made of grape juice boiled and dried on strings of nuts), Turkish delight (containing hazelnuts, pistachios, or walnuts), and pişmaniye (candy made of sugar, butter, and flour), were tested, and the performance of the method was established with spiked samples. To examine the robustness of the methodology, baklava was prepared from raw materials and spiked at the initial stage of dry ingredients and through subsequent stages of preparation of dough, after cooking, and after addition of syrup and nuts. For all products, the analytical method required grinding the composite foodstuff under liquid nitrogen to form a fine powder, which was then thoroughly mixed before subsampling. After vortex extraction into methanol-water (aflatoxins) and aqueous sodium bicarbonate (ochratoxin A), the sample was filtered, diluted with phosphate-buffered saline, and then passed through either an aflatoxin or ochratoxin A affinity column before HPLC analysis with fluorescence detection (using post-column bromination for the aflatoxins). In all the traditional Turkish products, the recovery of aflatoxin B1 ranged from 77 to 98%, and LODs were <0.1 microg/kg. For ochratoxin A, the recoveries were from 88 to 93% and LODs were similarly <0.1 microLg/kg. Despite the complex nature of these traditional Turkish foods, which frequently contain products from sugar caramelization, there was no evidence of any interfering co-extractives, and the method has proved to be robust enough to be used for food control purposes.

Persistence of 2,4-D and its effects on benthic macroinvertebrates following spring treatment of Eurasian Watermilfoil, Myriophyllum spicatum L. in two lakes in southeastern Wisconsin, USA.

PubMed

Harrahy, E A; Edwards, D S; Hedman, C J

2014-04-01

The purpose of this study was to determine the persistence of 2,4-dichlorophenoxyacetic acid (2,4-D) applied to two lakes (one mesotrophic and one eutrophic) for the control of Eurasian watermilfoil (EWM), and to determine the impacts of 2,4-D on benthic macroinvertebrates in one of the lakes. One lake was treated with a liquid formulation, and the other with a slow release granular formulation of 2,4-D. Concentrations of 2,4-D in the water column were highest 1 and 2 days post-treatment and declined to below detection limits by 7 and 10 days post-treatment. We observed negative correlations between days post-treatment and taxa richness, and between days post-treatment and abundance of three of 12 taxonomic groups of macroinvertebrates. Lake managers need to balance control of EWM with possible impacts of 2,4-D to nontarget organisms.

One simple DNA extraction device and its combination with modified visual loop-mediated isothermal amplification for rapid on-field detection of genetically modified organisms.

PubMed

Zhang, Miao; Liu, Yinan; Chen, Lili; Quan, Sheng; Jiang, Shimeng; Zhang, Dabing; Yang, Litao

2013-01-02

Quickness, simplicity, and effectiveness are the three major criteria for establishing a good molecular diagnosis method in many fields. Herein we report a novel detection system for genetically modified organisms (GMOs), which can be utilized to perform both on-field quick screening and routine laboratory diagnosis. In this system, a newly designed inexpensive DNA extraction device was used in combination with a modified visual loop-mediated isothermal amplification (vLAMP) assay. The main parts of the DNA extraction device included a silica gel membrane filtration column and a modified syringe. The DNA extraction device could be easily operated without using other laboratory instruments, making it applicable to an on-field GMO test. High-quality genomic DNA (gDNA) suitable for polymerase chain reaction (PCR) and isothermal amplification could be quickly isolated from plant tissues using this device within 15 min. In the modified vLAMP assay, a microcrystalline wax encapsulated detection bead containing SYBR green fluorescent dye was introduced to avoid dye inhibition and cross-contaminations from post-LAMP operation. The system was successfully applied and validated in screening and identification of GM rice, soybean, and maize samples collected from both field testing and the Grain Inspection, Packers, and Stockyards Administration (GIPSA) proficiency test program, which demonstrated that it was well-adapted to both on-field testing and/or routine laboratory analysis of GMOs.

Progress on development of an airborne two-micron IPDA lidar for water vapor and carbon dioxide column measurements

NASA Astrophysics Data System (ADS)

Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Yu, Jirong; Antill, Charles W.; Taylor, Bryant D.; Bowen, Stephen C.; Welters, Angela M.; Remus, Ruben G.; Wong, Teh-Hwa; Reithmaier, Karl; Lee, Jane; Ismail, Syed

2017-09-01

An airborne 2-μm triple-pulse integrated path differential absorption (IPDA) lidar is currently under development at NASA Langley Research Center (LaRC). This lidar targets both atmospheric carbon dioxide (CO2) and water vapor (H2O) column measurements, simultaneously. Advancements in the development of this IPDA lidar are presented in this paper. Updates on advanced two-micron triple-pulse high-energy laser transmitter will be given including packaging and lidar integration status. In addition, receiver development updates will also be presented. This includes a state-of-the-art detection system integrated at NASA Goddard Space Flight Center. This detection system is based on a newly developed HgCdTe (MCT) electron-initiated avalanche photodiode (e-APD) array. Future plan for IPDA lidar system for ground integration, testing and flight validation will be discussed.

Progress on Development of an Airborne Two-Micron IPDA Lidar for Water Vapor and Carbon Dioxide Column Measurements

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Yu, Jirong; Antill, Charles W.; Taylor, Bryant D.; Bowen, Stephen C.; Welters, Angela M.; Remus, Ruben G.; Wong, Teh-Hwa;

The simultaneous detection of trivalent & hexavalent chromium in exhaled breath condensate: A feasibility study comparing workers and controls.

PubMed

Leese, Elizabeth; Morton, Jackie; Gardiner, Philip H E; Carolan, Vikki A

2017-04-01

The analytical method outlined in this feasibility study has been used to show that trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)) can be detected and measured in exhaled breath condensate (EBC) samples. EBC samples and urine samples were collected from a cohort of 58 workers occupationally exposed to hexavalent chromium compounds and 22 unexposed volunteers (control group). Levels of Cr(III) and Cr(VI) were determined in EBC samples and total chromium levels were determined in urine samples. Pre and post working week samples for both EBC and urine were collected in tandem. Total chromium in urine samples was analysed by inductively coupled plasma mass spectrometry (ICP-MS). Analysis of Cr(III) and Cr(VI) in EBC samples used a hyphenated micro liquid chromatography (μLC) system coupled to an ICP-MS. Separation was achieved using an anion exchange micro-sized column. The results showed that the occupationally exposed workers had significantly higher levels of Cr(III) and Cr(VI) in their EBC samples than the control group, as well as higher levels of total chromium in their urine samples. However, for the exposed workers no significant difference was found between pre and post working week EBC samples for either Cr(III) or Cr(VI). This study has established that Cr(III) and Cr(VI) can simultaneously be detected and measured in 'real' EBC samples and will help in understanding inhalation exposure. Crown Copyright © 2016. Published by Elsevier GmbH. All rights reserved.

Interstellar C2, CH, and CN in translucent molecular clouds

NASA Technical Reports Server (NTRS)

Black, John H.; Van Dishoeck, Ewine F.

1989-01-01

Optical absorption-line techniques have been applied to the study of a number of translucent molecular clouds in which the total column densities are large enough that substantial molecular abundances can be maintained. Results are presented for a survey of absorption lines of interstellar C2, CH, and CN. Detections of CN through the A 2Pi-X 2Sigma(+) (1,O) and (2,O) bands of the red system are reported and compared with observations of the violet system for one line of sight. The population distributions in C2 provide diagnostic information on temperature and density. The measured column densities of the three species can be used to test details of the theory of molecule formation in clouds where photoprocesses still play a significant role. The C2 and CH column densities are strongly correlated with each other and probably also with the H2 column density. In contrast, the CN column densities are found to vary greatly from cloud to cloud. The observations are discussed with reference to detailed theoretical models.

Microfluidic chip for peptide analysis with an integrated HPLC column, sample enrichment column, and nanoelectrospray tip.

PubMed

Yin, Hongfeng; Killeen, Kevin; Brennen, Reid; Sobek, Dan; Werlich, Mark; van de Goor, Tom

2005-01-15

Current nano-LC/MS systems require the use of an enrichment column, a separation column, a nanospray tip, and the fittings needed to connect these parts together. In this paper, we present a microfabricated approach to nano-LC, which integrates these components on a single LC chip, eliminating the need for conventional LC connections. The chip was fabricated by laminating polyimide films with laser-ablated channels, ports, and frit structures. The enrichment and separation columns were packed using conventional reversed-phase chromatography particles. A face-seal rotary valve provided a means for switching between sample loading and separation configurations with minimum dead and delay volumes while allowing high-pressure operation. The LC chip and valve assembly were mounted within a custom electrospray source on an ion-trap mass spectrometer. The overall system performance was demonstrated through reversed-phase gradient separations of tryptic protein digests at flow rates between 100 and 400 nL/min. Microfluidic integration of the nano-LC components enabled separations with subfemtomole detection sensitivity, minimal carryover, and robust and stable electrospray throughout the LC solvent gradient.

Flow injection amperometric sensor with a carbon nanotube modified screen printed electrode for determination of hydroquinone.

PubMed

Upan, Jantima; Reanpang, Preeyaporn; Chailapakul, Orawon; Jakmunee, Jaroon

2016-01-01

Flow injection amperometric (FI-Amp) sensor was developed for sensitive and selective determination of hydroquinone. A simple screen printed carbon electrode (SPCE) was modified with various nanomaterials for improvement of sensitivity on the determination of quinone. As a result, the appropriate sensitivity is obtained from the SPCE modified with carbon nanotube (CNT) which indicated that CNT contributed to the transfer of electron to quinone. The reproducibility (n=9) and repeatability (n=111) of SPCE-CNT were obtained at 4.4% and 3.6%RSD, respectively. The SPCE-CNT electrode and enzymatic column were incorporated to the FI-Amp system to determine hydroquinone. Laccase was immobilized on silica gel using a cross-linking method by glutaraldehyde modification and then packed in the column. The laccase column has high efficiency for catalytic oxidation of hydroquinone to quinone, which further detects by amperometric detection. Parameters affecting response of the proposed sensor, i.e., pH, ionic strength, and temperature have been optimized. The proposed system provided a wide linear range between 1 and 50 µM with detection limit of 0.1 µM. Satisfactory recoveries in the range of 91.2-103.8% were obtained for the analysis of water sample. Copyright © 2015 Elsevier B.V. All rights reserved.

Automatic and integrated micro-enzyme assay (AIμEA) platform for highly sensitive thrombin analysis via an engineered fluorescence protein-functionalized monolithic capillary column.

PubMed

Lin, Lihua; Liu, Shengquan; Nie, Zhou; Chen, Yingzhuang; Lei, Chunyang; Wang, Zhen; Yin, Chao; Hu, Huiping; Huang, Yan; Yao, Shouzhuo

2015-04-21

Nowadays, large-scale screening for enzyme discovery, engineering, and drug discovery processes require simple, fast, and sensitive enzyme activity assay platforms with high integration and potential for high-throughput detection. Herein, a novel automatic and integrated micro-enzyme assay (AIμEA) platform was proposed based on a unique microreaction system fabricated by a engineered green fluorescence protein (GFP)-functionalized monolithic capillary column, with thrombin as an example. The recombinant GFP probe was rationally engineered to possess a His-tag and a substrate sequence of thrombin, which enable it to be immobilized on the monolith via metal affinity binding, and to be released after thrombin digestion. Combined with capillary electrophoresis-laser-induced fluorescence (CE-LIF), all the procedures, including thrombin injection, online enzymatic digestion in the microreaction system, and label-free detection of the released GFP, were integrated in a single electrophoretic process. By taking advantage of the ultrahigh loading capacity of the AIμEA platform and the CE automatic programming setup, one microreaction column was sufficient for many times digestion without replacement. The novel microreaction system showed significantly enhanced catalytic efficiency, about 30 fold higher than that of the equivalent bulk reaction. Accordingly, the AIμEA platform was highly sensitive with a limit of detection down to 1 pM of thrombin. Moreover, the AIμEA platform was robust and reliable to detect thrombin in human serum samples and its inhibition by hirudin. Hence, this AIμEA platform exhibits great potential for high-throughput analysis in future biological application, disease diagnostics, and drug screening.

Column compression strength of tubular packaging forms made from paper

Treesearch

Thomas J. Urbanik; Sung K. Lee; Charles G. Johnson

2006-01-01

Tubular packaging forms fabricated and shaped from rolled paper are used as reinforcing corner posts for major appliances packaged in corrugated containers. Tests of column compression strength simulate the expected performance loads from appliances stacked in warehouses. Column strength depends on tube geometry, paper properties, basis weight, and number of...

Evolution of the Pinatubo volcanic aerosol column above Pasadena, California observed with a mid-infrared backscatter lidar

NASA Technical Reports Server (NTRS)

Tratt, David M.; Menzies, Robert T.

1995-01-01

The evolution of the volcanic debris plume originating from the June 1991 eruption of Mt. Pinatubo has been monitored since its genesis using a ground-based backscatter lidar facility sited at the Jet Propulsion Laboratory (JPL). Both absolute and relative pre- and post-Pinatubo backscatter observations are in accord with Mie scattering projections based on measured aerosol particle size distributions reported in the literature. The post-Pinatubo column-integrated backscatter coefficient peaked approximately 400 days after the eruption, and the observed upper boundary of the aerosol column subsided at a rate of approximately 200 m/mon.

Quantification of cyclamate and cyclohexylamine in urine samples using high-performance liquid chromatography with trinitrobenzenesulfonic acid pre-column derivatization.

PubMed

Casals, I; Reixach, M; Amat, J; Fuentes, M; Serra-Majem, L

1996-10-25

An HPLC isocratic method with pre-column derivatization and UV detection for the quantification of cyclamate and cyclohexylamine in urine samples is described. The method requires very little sample preparation. Free cyclohexylamine is analysed in a first run and subsequently cyclamate is analysed as cyclohexylamine, after the simple process of oxidation of the sample by means of hydrogen peroxide. Cycloheptylamine is used as internal standard. Trinitrobenzenesulfonic acid (TNBS) appears to be a good reagent for the pre-column derivatization. The time per run is 15 min; the coefficients of variation of the assays range from 1.1 to 5.5%; the limits of detection are 0.09 and 0.11 ppm for cyclohexylamine and cyclamate anion, respectively. The system described has always performed efficiently, with a high degree of stability, in daily routine work.

Renewable Surface Fluorescence Sandwich Immunoassay Biosensor for Rapid Sensitive Botulinum Toxin Detection in an Automated Fluidic Format

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

Grate, Jay W.; Warner, Marvin G.; Ozanich, Richard M.

2009-03-05

A renewable surface biosensor for rapid detection of botulinum toxin is described based on fluidic automation of a fluorescence sandwich immunoassay, using a recombinant fragment of the toxin heavy chain as a structurally valid simulant. Monoclonal antibodies AR4 and RAZ1 bind to separate epitopes of both this fragment and the holotoxin. The AR4 antibody was covalently bound to Sepharose beads and used as the capture antibody. A rotating rod flow cell was used to capture these beads delivered as a suspension by the sequential injection flow system, creating a 3.6 microliter column. After perfusing the bead column with sample andmore » washing away the matrix, the column was perfused with Alexa 647 dye-labeled RAZ1 antibody as the reporter. Optical fibers coupled to the rotating rod flow cell at a 90 degree angle to one another delivered excitation light from a HeNe laser and collected fluorescent emission light for detection. After each measurement, the used sepharose beads are released and replaced with fresh beads. In a rapid screening approach to sample analysis, the toxin simulant was detected to concentrations of 10 pM in less than 20 minutes.« less

Determination of nitrite, nitrate, bromide, and iodide in seawater by ion chromatography with UV detection using dilauryldimethylammonium-coated monolithic ODS columns and sodium chloride as an eluent.

PubMed

Ito, Kazuaki; Nomura, Ryosuke; Fujii, Takuya; Tanaka, Masahito; Tsumura, Tomoaki; Shibata, Hiroyuki; Hirokawa, Takeshi

2012-11-01

A method was developed for determination of inorganic anions, including nitrite (NO(2)(-)), nitrate (NO(3)(-)), bromide (Br(-)), and iodide (I(-)), in seawater by ion chromatography (IC). The IC system used two dilauryldimethylammonium bromide (DDAB)-coated monolithic ODS columns (50 × 4.6 mm i.d. and 100 × 4.6 mm i.d.) connected in series for separation of the ions. Aqueous NaCl (0.5 mol/L; flow rate, 3 mL/min) containing 5 mmol/L phosphate buffer (pH 5) was used as the eluent, and detection was with a UV detector at 225 nm. The monolithic ODS columns were coated and equilibrated with a 1-mmol/L DDAB solution (in H(2)O/methanol, 90:10 v/v). The hydrophilic ions (NO(2)(-), NO(3)(-), and Br(-)) were separated within 3 min and the retention time of I(-) was 16 min. No interferences from matrix ions, such as chloride and sulfate ions, were observed in 35 ‰ artificial seawater. The detection limits were 0.6 μg/L for NO(2)(-), 1.1 μg/L for NO(3)(-), 70 μg/L for Br(-), and 1.6 μg/L for I(-) with a 200-μL sample injection. The performance of the coated columns was maintained without addition of DDAB in the eluent. The IC system was successfully applied to real seawater samples with recovery rates of 94-108 % for all ions.

Comparative reduction of Norwalk virus, poliovirus type 1, F+ RNA coliphage MS2 and Escherichia coli in miniature soil columns.

PubMed

Meschke, J S; Sobsey, M D

2003-01-01

Norwalk-like viruses (NLVs) are important agents of waterborne illness and have been linked to several groundwater-related outbreaks. The presence of human enteric viruses, in particular the presence of NLVs, is difficult to detect in the environment. Consequently, surrogate organisms are typically used as indicators of viruses from faecal contamination. Whether traditional bacterial indicators are reliable indicators for viral pathogens remains uncertain. Few studies have directly compared mobility and reduction of bacterial indicators (e.g. coliforms, Escherichia coli) and other surrogate indicators (coliphages) with pathogenic human viruses in soil systems. In this study the mobility and comparative reduction of the prototype NLV, Norwalk Virus (NV), was compared to poliovirus 1 (PV1), a bacterial indicator (E coli, EC) and a viral indicator (coliphage MS2) through miniature soil columns. Replicate, 10 cm deep, miniature columns were prepared using three soils representing a range of soil textures (sand, organic muck, and clay). Columns were initially conditioned, then incubated at 10-14 degrees C, dosed twice weekly for 8 weeks with one column pore volume of virus-seeded groundwater per dose, followed by 8 weeks of dosing with one column pore volume per dose of unseeded, simulated rainwater. Columns were allowed to drain after each dosing until an effluent volume equivalent to an applied dose was collected. Column effluents and doses were assayed for all viruses and EC. Rapid mobility with minimal reduction was observed for all organisms in the sand. Similar reductions were observed in organic muck for most organisms but NV showed a greater reduction. No organisms were shown to pass through the clay columns. Elution of viruses, in particular PV1, from the columns was gradual. After cessation of microbe dosing, E. coli was less detectable than viruses in column effluents and, therefore, unreliable as a virus indicator.

Integrated multiplexed capillary electrophoresis system

DOEpatents

Yeung, Edward S.; Tan, Hongdong

2002-05-14

The present invention provides an integrated multiplexed capillary electrophoresis system for the analysis of sample analytes. The system integrates and automates multiple components, such as chromatographic columns and separation capillaries, and further provides a detector for the detection of analytes eluting from the separation capillaries. The system employs multiplexed freeze/thaw valves to manage fluid flow and sample movement. The system is computer controlled and is capable of processing samples through reaction, purification, denaturation, pre-concentration, injection, separation and detection in parallel fashion. Methods employing the system of the invention are also provided.

Liquid Chromatography with Post-Column Reagent Addition of Ammonia in Methanol Coupled to Negative Ion Electrospray Ionization Tandem Mass Spectrometry for Determination of Phenoxyacid Herbicides and their Degradation Products in Surface Water

PubMed Central

Raina, Renata; Etter, Michele L.

2010-01-01

A new liquid chromatography (LC)-negative ion electrospray ionization (ESI−)–tandem mass spectrometry (MS/MS) method with post-column addition of ammonia in methanol has been developed for the analysis of acid herbicides: 2,4-dichlorophenoxy acetic acid, 4-chloro-o-tolyloxyacetic acid, 2-(2-methyl-4-chlorophenoxy)butyric acid, mecoprop, dichlorprop, 4-(2,4-dichlorophenoxy) butyric acid, 2,4,5-trichlorophenoxy propionic acid, dicamba and bromoxynil, along with their degradation products: 4-chloro-2-methylphenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol and 3,5-dibromo-4-hydroxybenzoic acid. The samples were extracted from the surface water matrix using solid-phase extraction (SPE) with a polymeric sorbent and analyzed with LC ESI− with selected reaction monitoring (SRM) using a three-point confirmation approach. Chromatography was performed on a Zorbax Eclipse XDB-C18 (50 × 4.6 mm i.d., 1.8 μm) with a gradient elution using water-methanol with 2 mM ammonium acetate mobile phase at a flow rate of 0.15 mL/min. Ammonia in methanol (0.8 M) was added post-column at a flow rate of 0.05 mL/min to enhance ionization of the degradation products in the MS source. One SRM transition was used for quantitative analysis while the second SRM along with the ratio of SRM1/SRM2 within the relative standard deviation determined by standards for each individual pesticide and retention time match were used for confirmation. The standard deviation of ratio of SRM1/SRM2 obtained from standards run on the day of analysis for different phenoxyacid herbicides ranged from 3.9 to 18.5%. Limits of detection (LOD) were between 1 and 15 ng L−1 and method detection limits (MDL) with strict criteria requiring <25% deviation of peak area from best-fit line for both SRM1 and SRM2 ranged from 5 to 10 ng L−1 for acid ingredients (except dicamba at 30 ng L−1) and from 2 to 30 ng L−1 for degradation products. The SPE-LC-ESI− MS/MS method permitted low nanogram-per-liter determination of pesticides and degradation products for surface water samples. PMID:20212919

Detection of Oil in Water Column: Sensor Design

DTIC Science & Technology

2013-02-01

rivers , and initiating dispersant application or oil recovery operations. Challenges in detecting oil within the water column include poor...facility and along transects in the Delaware River . However, all readings were at background, even when there was visible oil on the water surface...levels for extremely high CDOM rich rivers . Detection of Oil in Water Column: Sensor Design 14 UNCLAS//Public | CG-926 RDC | Fitzpatrick, et al

Derringer desirability and kinetic plot LC-column comparison approach for MS-compatible lipopeptide analysis.

PubMed

D'Hondt, Matthias; Verbeke, Frederick; Stalmans, Sofie; Gevaert, Bert; Wynendaele, Evelien; De Spiegeleer, Bart

2014-06-01

Lipopeptides are currently re-emerging as an interesting subgroup in the peptide research field, having historical applications as antibacterial and antifungal agents and new potential applications as antiviral, antitumor, immune-modulating and cell-penetrating compounds. However, due to their specific structure, chromatographic analysis often requires special buffer systems or the use of trifluoroacetic acid, limiting mass spectrometry detection. Therefore, we used a traditional aqueous/acetonitrile based gradient system, containing 0.1% (m/v) formic acid, to separate four pharmaceutically relevant lipopeptides (polymyxin B 1 , caspofungin, daptomycin and gramicidin A 1 ), which were selected based upon hierarchical cluster analysis (HCA) and principal component analysis (PCA). In total, the performance of four different C18 columns, including one UPLC column, were evaluated using two parallel approaches. First, a Derringer desirability function was used, whereby six single and multiple chromatographic response values were rescaled into one overall D -value per column. Using this approach, the YMC Pack Pro C18 column was ranked as the best column for general MS-compatible lipopeptide separation. Secondly, the kinetic plot approach was used to compare the different columns at different flow rate ranges. As the optimal kinetic column performance is obtained at its maximal pressure, the length elongation factor λ ( P max / P exp ) was used to transform the obtained experimental data (retention times and peak capacities) and construct kinetic performance limit (KPL) curves, allowing a direct visual and unbiased comparison of the selected columns, whereby the YMC Triart C18 UPLC and ACE C18 columns performed as best. Finally, differences in column performance and the (dis)advantages of both approaches are discussed.

Capillary liquid chromatographic analysis of fat-soluble vitamins and beta-carotene in combination with in-tube solid-phase microextraction.

PubMed

Xu, Hui; Jia, Li

2009-01-01

A capillary liquid chromatography (CLC) system with UV/vis detection was coupled with an in-tube solid-phase microextraction (SPME) device for the analysis of fat-soluble vitamins and beta-carotene. A monolithic silica-ODS column was used as the extraction medium. An optical-fiber flow cell with a long light path in the UV/vis detector was utilized to further enhance the detection sensitivity. In the in-tube SPME/CLC system, the pre-condition of the extraction column and the effect of the injection volume were investigated. The detection limits (LOD) for the fat-soluble vitamins and beta-carotene were in the range from 1.9 to 173 ng/mL based on the signal-to-noise ratio of 3 (S/N=3). The relative standard deviations of migration time and peak area for each analyte were less than 5.0%. The method was applied to the analysis of fat-soluble vitamins and beta-carotene contents in corns.

Unbonded Prestressed Columns for Earthquake Resistance

DOT National Transportation Integrated Search

2012-05-01

Modern structures are able to survive significant shaking caused by earthquakes. By implementing unbonded post-tensioned tendons in bridge columns, the damage caused by an earthquake can be significantly lower than that of a standard reinforced concr...

Evaluation of an ODS column modified with zwitterionic/nonionic mixed surfactants and its application to direct injection determination of inorganic anions.

PubMed

Hasegawa, Takuya; Umemura, Tomonari; Koide, Akira; Chiba, Koichi; Ueki, Yuji; Tsunoda, Kin-ichi; Haraguchi, Hiroki

2005-08-01

An octadecylsilica (ODS) column modified with zwitterionic/nonionic mixed surfactants was evaluated for the direct injection determination of inorganic anions in biological fluids by ion chromatography. A zwitterionic surfactant (sulfobetaine-type) and a nonionic surfactant (polyoxyethylene-type) were used for a stationary-phase modification. When aqueous electrolyte solutions with concentrations of sub-mM to several mM were used as a mobile phase, the zwitterionic surfactant coated on the ODS surface exhibited unique separation selectivity for ionic species, while the nonionic surfactant coated on the ODS might have formed a hydrophilic network over the ODS surface and restricted matrix proteins from adsorbing on the stationary phase. Consequently, the mixed surfactant-modified column system allowed an efficient ion chromatographic separation of inorganic anions as well as a size-exclusive removal of column-fouling proteins. This separation system was applied to the direct injection determination of UV-absorbing anions in human saliva. The detection limits for nitrite, nitrate, iodide and thiocyanate were 3.1, 2.7, 4.5 and 25 microM, respectively, with UV detection at 210 nm (injection volume; 20 microl), and their relative standard deviations for 5 replicate measurements of saliva samples spiked with 100 microM each of those anions were 1.4, 0.9, 2.2 and 5.5%, respectively.

Determination of doxorubicin in plasma by using CE coupled with in-column tapered optic-fiber light-emitting diode induced fluorescence detection.

PubMed

Yang, Xiupei; Qian, Fan; Xie, Linxiang; Yang, Xiaocui; Cheng, Xiumei; Choi, Martin M F

2014-03-01

This paper proposes a novel strategy to enhance detection of doxorubicin in human plasma, using homemade CE combined with normal stacking mode (NSM). The detection system of CE named as in-column tapered optic-fiber light-emitting diode induced fluorescence detection system is economic and more sensitive that has been demonstrated in our previous work. The influence of sample matrix, BGE, applied voltage, and injection time on the efficiency of NSM were systematically investigated. The clean extracts were subjected to CE separation with optimal experimental conditions: Ethanol-water (1:1, v/v) was used as sample matrix, pH 4.12 15 mM sodium phosphate buffer solution containing 70% v/v ACN, applied voltage 23 kV and 45 s hydrodynamic injection at a height of 20 cm. The detection system displayed linear dynamic range from 6.4 to 1.13 × 10(3) ng/mL with a correlation coefficient of 0.9990 and LOD 2.2 ng/mL for doxorubicin (DOX). The proposed CE method has been successfully applied to determine DOX in human plasma which the recoveries of standard DOX added to human plasma were found to been the range of 93.8-104.6%. The results obtained demonstrate that our detection system combined with NSM is a good idea to enhance sensitivity in CE for routine determination of DOX in some biological specimens. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis of pharmaceutical impurities using multi-heartcutting 2D LC coupled with UV-charged aerosol MS detection.

PubMed

Zhang, Kelly; Li, Yi; Tsang, Midco; Chetwyn, Nik P

2013-09-01

To overcome challenges in HPLC impurity analysis of pharmaceuticals, we developed an automated online multi-heartcutting 2D HPLC system with hyphenated UV-charged aerosol MS detection. The first dimension has a primary column and the second dimension has six orthogonal columns to enhance flexibility and selectivity. The two dimensions were interfaced by a pair of switching valves equipped with six trapping loops that allow multi-heartcutting of peaks of interest in the first dimension and also allow "peak parking." The hyphenated UV-charged aerosol MS detection provides comprehensive detection for compounds with and without UV chromophores, organics, and inorganics. It also provides structural information for impurity identification. A hidden degradation product that co-eluted with the drug main peak was revealed by RP × RP separation and thus enabled the stability-indicating method development. A poorly retained polar component with no UV chromophores was analyzed by RP × hydrophilic interaction liquid chromatography separation with charged aerosol detection. Furthermore, using this system, the structures of low-level impurities separated by a method using nonvolatile phosphate buffer were identified and tracked by MS in the second dimension. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Water column imaging on hydrothermal vent in Central Indian Ridge

NASA Astrophysics Data System (ADS)

Koh, J.; Park, Y.

2017-12-01

Water column imaging with Multibeam echosounder systems (MBES) is recently becoming of increasing interest for oceanographic studies. Especially gas bubbles and hot water exposed from hydrothermal vents make acoustic impedance anomalies in cold seawater, water column imaging is very useful for the researchers who want to detect some kinds of hydrothermal activity. We conducted a hydrothermal exploration program, called "INVENT17", using the MBES system, KONGBERG EM122 (12kHz, 1°×1°), mounted on R/V ISABU and we deployed other equipments including video guided hydraulic grab, tow-yo CTD and general CTD with MAPR (Miniature Autonomous Plume Recorder) in 2017. First, to evaluate its capabilities of detection of hydrothermal vent, the surveys using the MBES were conducted at the Solitaire Field, previously identified hydrothermal area of the Central Indian Ridge. The bathymetric data obtained from MBES provided information about detailed morphology of seafloor, but we were not able to achieve the information from the water column imaging data. But the clue of existence of active hydrothermal vent was detected through the values of ΔNTU, dEh/dt, and OPR gained from MAPR, the data means that the hydrothermal activity affects 100m from the seafloor. It could be the reason that we can't find the hydrothermal activity because the range resolution of water column imaging is pretty rough so that the size of 100m-scaled activity has low possibility to distinguish from seafloor. The other reason is there are no sufficient objects to cause strong scattering like as CO2 bubbles or droplets unlike in the mid-Okinawa Trough. And this suggests that can be a important standard to identify properties of hydrothermal vent sites depending on the presence of scattering objects in water mass. To justify this, we should perform more chemical analysis of hot water emanating from hydrothermal vent and collected several bottles of water sample to do that.

High-sensitivity direct analysis of aflatoxins in peanuts and cereal matrices by ultra-performance liquid chromatography with fluorescence detection involving a large volume flow cell.

PubMed

Oulkar, Dasharath; Goon, Arnab; Dhanshetty, Manisha; Khan, Zareen; Satav, Sagar; Banerjee, Kaushik

2018-04-03

This paper reports a sensitive and cost effective method of analysis for aflatoxins B1, B2, G1 and G2. The sample preparation method was primarily optimised in peanuts, followed by its validation in a range of peanut-processed products and cereal (rice, corn, millets) matrices. Peanut slurry [12.5 g peanut + 12.5 mL water] was extracted with methanol: water (8:2, 100 mL), cleaned through an immunoaffinity column and thereafter measured directly by ultra-performance liquid chromatography-fluorescence (UPLC-FLD) detection, within a chromatographic runtime of 5 minutes. The use of a large volume flow cell in the FLD nullified the requirement of any post-column derivatisation and provided the lowest ever reported limits of quantification of 0.025 for B1 and G1 and 0.01 μg/kg for B2 and G2. The single laboratory validation of the method provided acceptable selectivity, linearity, recovery and precision for reliable quantifications in all the test matrices as well as demonstrated compliance with the EC 401/2006 guidelines for analytical quality control of aflatoxins in foodstuffs.

Distribution of tetrodotoxin in the body of the blue-ringed octopus (Hapalochlaena maculosa).

PubMed

Yotsu-Yamashita, Mari; Mebs, Dietrich; Flachsenberger, Wolfgang

2007-03-01

Tetrodotoxin (TTX) was quantitatively assayed in six specimens of semi-adult blue-ringed octopus, Hapalochlaena maculosa, by a post-column fluorescent-HPLC system. TTX was found to be present in all body parts, e.g. in high concentrations in the arms followed by the abdomen and cephalothorax. The toxin is not associated exclusively with the posterior salivary gland.

Effect of load eccentricity on the buckling of thin-walled laminated C-columns

NASA Astrophysics Data System (ADS)

Wysmulski, Pawel; Teter, Andrzej; Debski, Hubert

2018-01-01

The study investigates the behaviour of short, thin-walled laminated C-columns under eccentric compression. The tested columns are simple-supported. The effect of load inaccuracy on the critical and post-critical (local buckling) states is examined. A numerical analysis by the finite element method and experimental tests on a test stand are performed. The samples were produced from a carbon-epoxy prepreg by the autoclave technique. The experimental tests rest on the assumption that compressive loads are 1.5 higher than the theoretical critical force. Numerical modelling is performed using the commercial software package ABAQUS®. The critical load is determined by solving an eigen problem using the Subspace algorithm. The experimental critical loads are determined based on post-buckling paths. The numerical and experimental results show high agreement, thus demonstrating a significant effect of load inaccuracy on the critical load corresponding to the column's local buckling.

Trace analysis of impurities in bulk gases by gas chromatography-pulsed discharge helium ionization detection with "heart-cutting" technique.

PubMed

Weijun, Yao

2007-10-12

A method has been developed for the detection of low-nL/L-level impurities in bulk gases such as H(2), O(2), Ar, N(2), He, methane, ethylene and propylene, respectively. The solution presented here is based upon gas chromatography-pulsed discharge helium ionization detection (GC-PDHID) coupled with three two-position valves, one two-way solenoid valve and four packed columns. During the operation, the moisture and heavy compounds are first back-flushed via a pre-column. Then the trace impurities (except CO(2) which is diverted to a separate analytical column for separation and detection) together with the matrix enter onto a main column, followed by the heart-cut of the impurities onto a longer analytical column for complete separation. Finally the detection is performed by PDHID. This method has been applied to different bulk gases and the applicability of detecting impurities in H(2), Ar, and N(2) are herewith demonstrated. As an example, the resulting detection limit of 100 nL/L and a dynamic range of 100-1000 nL/L have been obtained using an Ar sample containing methane.

Contactless Inductive Bubble Detection in a Liquid Metal Flow

PubMed Central

Gundrum, Thomas; Büttner, Philipp; Dekdouk, Bachir; Peyton, Anthony; Wondrak, Thomas; Galindo, Vladimir; Eckert, Sven

2016-01-01

The detection of bubbles in liquid metals is important for many technical applications. The opaqueness and the high temperature of liquid metals set high demands on the measurement system. The high electrical conductivity of the liquid metal can be exploited for contactless methods based on electromagnetic induction. We will present a measurement system which consists of one excitation coil and a pickup coil system on the opposite sides of the pipe. With this sensor we were able to detect bubbles in a sodium flow inside a stainless steel pipe and bubbles in a column filled with a liquid Gallium alloy. PMID:26751444

Column switching combined with hydrophilic interaction chromatography-tandem mass spectrometry for the analysis of saxitoxin analogues, and their biosynthetic intermediates in dinoflagellates.

PubMed

Cho, Yuko; Tsuchiya, Shigeki; Yoshioka, Renpei; Omura, Takuo; Konoki, Keiichi; Oshima, Yasukatsu; Yotsu-Yamashita, Mari

2016-11-25

Hydrophilic-interaction chromatography (HILIC) is reportedly useful for the analysis of saxitoxin (STX) analogues, collectively known as paralytic shellfish toxins. Column switching and two-step gradient elution using HILIC combined with mass spectrometry enabled the simultaneous analysis of the 15 primary STX analogues and their biosynthetic intermediates, arginine, Int-A', and Int-C'2, and the shunt product, Cyclic-C'. Crude extracts of toxin-producing dinoflagellates can be injected without any treatment except filtration. Enrichment of the compounds using this method was highly reproducible with respect to retention times (% RSD was under 1%) and highly sensitive (limits of detection (LODs) were in the range 0.9 (Int-C'2) - 116 (C3) μM) in terms of avoiding matrix effects associated with co-eluting substances. Validation studies demonstrated acceptable performance of this method for specificity, repeatability, linearity and recovery. A comparison of the quantitative results for STX analogues in Alexandrium tamarense using HPLC with post-column fluorescent derivatization and the column-switching HILIC-MS method revealed good agreement. The presence of Int-A', Int-C'2, and Cyclic-C' in toxic dinoflagellate species with different toxin profiles was confirmed using this method. Our data support the hypothesis that the early stages of the STX biosynthesis and shunt pathways are the same in dinoflagellates and cyanobacteria. Copyright © 2016 Elsevier B.V. All rights reserved.

A 780 × 800 μm2 Multichannel Digital Silicon Photomultiplier With Column-Parallel Time-to-Digital Converter and Basic Characterization

NASA Astrophysics Data System (ADS)

Mandai, Shingo; Jain, Vishwas; Charbon, Edoardo

2014-02-01

This paper presents a digital silicon photomultiplier (SiPM) partitioned in columns, whereas each column is connected to a column-parallel time-to-digital converter (TDC), in order to improve the timing resolution of single-photon detection. By reducing the number of pixels per TDC using a sharing scheme with three TDCs per column, the pixel-to-pixel skew is reduced. We report the basic characterization of the SiPM, comprising 416 single-photon avalanche diodes (SPADs); the characterization includes photon detection probability, dark count rate, afterpulsing, and crosstalk. We achieved 264-ps full-width at half maximum timing resolution of single-photon detection using a 48-fold column-parallel TDC with a temporal resolution of 51.8 ps (least significant bit), fully integrated in standard complementary metal-oxide semiconductor technology.

Aldicarb poisoning: one case report.

PubMed

Proença, Paula; Teixeira, Helena; de Mendonça, M C; Castanheira, Fernando; Marques, Estela P; Corte-Real, Francisco; Nuno Vieira, Duarte

2004-12-02

The carbamate aldicarb (Temik) is a highly toxic (LD50 = 0.9 mg/kg oral in rats) insecticide often used in agriculture. The authors present a fatal intoxication case with aldicarb, in a 24-year-old male, under police custody in the island of S. Tome and Prince (STP), in Africa. He was found 3 h after his arrest, lying on the floor of his cell, unconscious, frothing at the mouth, and entered into the hospital already dead. Aldicarb analysis was carried out by high-performance liquid chromatography, with a post-column derivatization system (with o-phthaldialdehyde and 2-mercaptoethanol, under alkaline conditions at 80 degrees C) with fluorescence detection at lambda(ex)= 339 nm and lambda(em) = 445 nm. The toxicological analysis revealed toxic concentrations of aldicarb in the post-mortem samples: blood (6.2 microg/ml), stomach (48.9 microg/g), liver (0.80 microg/g), kidney (8.10 microg/g), heart (6.70 microg/g) and urine (17.50 microg/ml). It was also detected to be the same substance in a grey granulate powder supplied by criminal authorities of that country, as a probable substance ingested by the victim. The toxicological analysis results, the autopsy findings and the information given, allowed us to conclude that death occurred due to an aldicarb acute intoxication. Although the case suggested a suicide, particularly based on the known information and on the high aldicarb concentration found in the stomach, it was not possible to indicate precisely its etiology (suicide or homicide).

Plastic buckling. [post-bifurcation and imperfection sensitivity

NASA Technical Reports Server (NTRS)

Hutchinson, J. W.

1974-01-01

The present article is concerned mainly with the post-bifurcation and imperfection-sensitivity aspects of plastic buckling. A simple two-degree-of-freedom model is used to introduce post-bifurcation behavior and a second model illustrates features of the behavior of continuous solids and structures. Hill's bifurcation criterion for a class of three-dimensional solids is applied to the Donnell-Mushtari-Vlasov (DMV) theory of plates and shells. A general treatment of the initial post-bifurcation behavior of plates and shells is given within the context of the DMV theory. This is illustrated by problems involving columns and circular plates under radial compression. Numerical results are given for a column under axial compression, a circular plate under radial compression, and spherical and cylindrical shells.

Biomechanical investigation of two plating systems for medial column fusion in foot

PubMed Central

Simons, Paul; Sommerer, Theresia; Zderic, Ivan; Wahl, Dieter; Lenz, Mark; Skulev, Hristo; Knobe, Matthias; Gueorguiev, Boyko; Richards, R. Geoff; Klos, Kajetan

2017-01-01

Background Arthrodesis of the medial column (navicular, cuneiform I and metatarsal I) is performed for reasons such as Charcot arthropathy, arthritis, posttraumatic reconstruction or severe pes planus. However, the complication rate is still high and mainly resulting from inadequate fixation. Special plates, designed for medial column arthrodesis, seem to offer potential to reduce the complication rate. The aim of this study was to investigate biomechanically plantar and dorsomedial fusion of the medial column using two new plating systems. Methods Eight matched pairs of human cadaveric lower legs were randomized in two groups and medial column fusion was performed using either plantar or dorsomedial variable-angle locking compression plates. The specimens were biomechanically tested under cyclic progressively increasing axial loading with physiological profile of each cycle. In addition to the machine data, mediolateral x-rays were taken every 250 cycles and motion tracking was performed to determine movements at the arthrodesis site. Statistical analysis of the parameters of interest was performed at a level of significance p = 0.05. Results Displacement of the talo-navicular joint after 1000, 2000 and 4000 cycles was significantly lower for plantar plating (p≤0.039) while there was significantly less movement in the naviculo-cuneiform I joint for dorsal plating post these cycle numbers (p<0.001). Displacements in all three joints of the medial column, as well as angular and torsional deformations between the navicular and metatarsal I increased significantly for each plating technique between 1000, 2000 and 4000 cycles (p≤0.021). The two plating systems did not differ significantly with regard to stiffness and cycles to failure (p≥0.171). Conclusion From biomechanical point of view, although dorsomedial plating showed less movement than plantar plating in the current setup under dynamic loading, there was no significant difference between the two plating systems with regard to stiffness and cycles to failure. Both tested techniques for dorsomedial and plantar plating appear to be applicable for arthrodesis of the medial column of the foot and other considerations, such as access morbidity, associated deformities or surgeon's preference, may also guide the choice of plating pattern. Further clinical studies are necessary before definitive recommendations can be given. PMID:28222170

Biomechanical investigation of two plating systems for medial column fusion in foot.

PubMed

Simons, Paul; Sommerer, Theresia; Zderic, Ivan; Wahl, Dieter; Lenz, Mark; Skulev, Hristo; Knobe, Matthias; Gueorguiev, Boyko; Richards, R Geoff; Klos, Kajetan

2017-01-01

Arthrodesis of the medial column (navicular, cuneiform I and metatarsal I) is performed for reasons such as Charcot arthropathy, arthritis, posttraumatic reconstruction or severe pes planus. However, the complication rate is still high and mainly resulting from inadequate fixation. Special plates, designed for medial column arthrodesis, seem to offer potential to reduce the complication rate. The aim of this study was to investigate biomechanically plantar and dorsomedial fusion of the medial column using two new plating systems. Eight matched pairs of human cadaveric lower legs were randomized in two groups and medial column fusion was performed using either plantar or dorsomedial variable-angle locking compression plates. The specimens were biomechanically tested under cyclic progressively increasing axial loading with physiological profile of each cycle. In addition to the machine data, mediolateral x-rays were taken every 250 cycles and motion tracking was performed to determine movements at the arthrodesis site. Statistical analysis of the parameters of interest was performed at a level of significance p = 0.05. Displacement of the talo-navicular joint after 1000, 2000 and 4000 cycles was significantly lower for plantar plating (p≤0.039) while there was significantly less movement in the naviculo-cuneiform I joint for dorsal plating post these cycle numbers (p<0.001). Displacements in all three joints of the medial column, as well as angular and torsional deformations between the navicular and metatarsal I increased significantly for each plating technique between 1000, 2000 and 4000 cycles (p≤0.021). The two plating systems did not differ significantly with regard to stiffness and cycles to failure (p≥0.171). From biomechanical point of view, although dorsomedial plating showed less movement than plantar plating in the current setup under dynamic loading, there was no significant difference between the two plating systems with regard to stiffness and cycles to failure. Both tested techniques for dorsomedial and plantar plating appear to be applicable for arthrodesis of the medial column of the foot and other considerations, such as access morbidity, associated deformities or surgeon's preference, may also guide the choice of plating pattern. Further clinical studies are necessary before definitive recommendations can be given.

Advanced Weapon System (AWS) Sensor Prediction Techniques Study. Volume I

DTIC Science & Technology

1981-09-01

row and column rather than random. The efficiency of the aigorithm depends on the fact that the grid coordinate system is aligned with the viewray ...pixels. Since the viewscreen is aligned with data base coordinates, the viewray intersections with a row of elevation posts are equally spaced at any...Surface Topography If a viewray strikes but a single terrain face, the viewray will be assigned the color of the face. If the viewray strikes two or

Randomized subspace-based robust principal component analysis for hyperspectral anomaly detection

NASA Astrophysics Data System (ADS)

Sun, Weiwei; Yang, Gang; Li, Jialin; Zhang, Dianfa

2018-01-01

A randomized subspace-based robust principal component analysis (RSRPCA) method for anomaly detection in hyperspectral imagery (HSI) is proposed. The RSRPCA combines advantages of randomized column subspace and robust principal component analysis (RPCA). It assumes that the background has low-rank properties, and the anomalies are sparse and do not lie in the column subspace of the background. First, RSRPCA implements random sampling to sketch the original HSI dataset from columns and to construct a randomized column subspace of the background. Structured random projections are also adopted to sketch the HSI dataset from rows. Sketching from columns and rows could greatly reduce the computational requirements of RSRPCA. Second, the RSRPCA adopts the columnwise RPCA (CWRPCA) to eliminate negative effects of sampled anomaly pixels and that purifies the previous randomized column subspace by removing sampled anomaly columns. The CWRPCA decomposes the submatrix of the HSI data into a low-rank matrix (i.e., background component), a noisy matrix (i.e., noise component), and a sparse anomaly matrix (i.e., anomaly component) with only a small proportion of nonzero columns. The algorithm of inexact augmented Lagrange multiplier is utilized to optimize the CWRPCA problem and estimate the sparse matrix. Nonzero columns of the sparse anomaly matrix point to sampled anomaly columns in the submatrix. Third, all the pixels are projected onto the complemental subspace of the purified randomized column subspace of the background and the anomaly pixels in the original HSI data are finally exactly located. Several experiments on three real hyperspectral images are carefully designed to investigate the detection performance of RSRPCA, and the results are compared with four state-of-the-art methods. Experimental results show that the proposed RSRPCA outperforms four comparison methods both in detection performance and in computational time.

Ultraperformance convergence chromatography-high resolution tandem mass spectrometry for lipid biomarker profiling and identification.

PubMed

Jones, Jace W; Carter, Claire L; Li, Fei; Yu, Jianshi; Pierzchalski, Keely; Jackson, Isabel L; Vujaskovic, Zeljko; Kane, Maureen A

2017-03-01

Lipids represent biologically ubiquitous and highly dynamic molecules in terms of abundance and structural diversity. Whereas the potential for lipids to inform on disease/injury is promising, their unique characteristics make detection and identification of lipids from biological samples analytically demanding. We report the use of ultraperformance convergence chromatography (UPC 2 ), a variant of supercritical fluid chromatography, coupled to high-resolution, data-independent tandem mass spectrometry for characterization of total lipid extracts from mouse lung tissue. The UPC 2 platform resulted in lipid class separation and when combined with orthogonal column chemistries yielded chromatographic separation of intra-class species based on acyl chain hydrophobicity. Moreover, the combined approach of using UPC 2 with orthogonal column chemistries, accurate mass measurements, time-aligned low- and high-collision energy total ion chromatograms, and positive and negative ion mode product ion spectra correlation allowed for confident lipid identification. Of great interest was the identification of differentially expressed ceramides that were elevated 24 h post whole thorax lung irradiation. The identification of lipids that were elevated 24 h post-irradiation signifies a unique opportunity to investigate early mechanisms of action prior to the onset of clinical symptoms in the whole thorax lung irradiation mouse model. Copyright © 2016 John Wiley & Sons, Ltd.

Impacts of CO2 Leakage on a Shallow Aquifer System: Laboratory Column Experiments and Reactive Transport Modeling

NASA Astrophysics Data System (ADS)

Ha, Jong Heon; Jeen, Sung-Wook

2017-04-01

Groundwater quality change due to the leakage of CO2 in a shallow aquifer system is an important aspect of environmental impact assessment in a carbon dioxide capture and storage (CCS) site. This study evaluated geochemical changes in a shallow aquifer system resulting from leakage of CO2 through laboratory column experiments and reactive transport modeling. In the column experiments, two columns were set up and filled with the sediment from the Environmental Impact Test (EIT) facility of the Korea CO2 Storage Environmental Management (K-COSEM) Research Center. Groundwater, also collected form the EIT site, was purged with CO2 or Ar gases, and was pumped into the columns with the pumping rates of 200-1000 mL day-1 (0.124-0.62 m day-1). Profile and time-series effluent samplings were conducted to evaluate the spatial and temporal geochemical changes in the aquifer materials upon contact with CO2. The experimental results showed that after injecting CO2-purged groundwater, the pH was decreased, and alkalinity, electrical conductivity (EC) and concentrations of major cations were increased. The spatial and temporal geochemical changes from the column experiments indicate that dissolution of aquifer materials in contact with dissolved CO2 is the major contributor to the changes in groundwater geochemistry. The reactive transport modeling has been conducted to reproduce these geochemical changes in the aquifer system by incorporating dissolution of the dominant aluminosilicate minerals in the aquifer such as microcline, anorthite, albite, and biotite. This study suggests that pH, alkalinity, EC and concentrations of major cations are important monitoring parameters for detecting CO2 leakage in a shallow groundwater aquifer system.

High speed infrared imaging system and method

DOEpatents

Zehnder, Alan T.; Rosakis, Ares J.; Ravichandran, G.

2001-01-01

A system and method for radiation detection with an increased frame rate. A semi-parallel processing configuration is used to process a row or column of pixels in a focal-plane array in parallel to achieve a processing rate up to and greater than 1 million frames per second.

Buried object detection in GPR images

DOEpatents

Paglieroni, David W; Chambers, David H; Bond, Steven W; Beer, W. Reginald

2014-04-29

A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

Field and Laboratory Application of a Gas Chromatograph Low Thermal Mass Resistively Heated Column System in Detecting Traditional and Non-Traditional Chemical Warfare Agents Using Solid Phase Micro-Extraction

DTIC Science & Technology

2005-02-01

followed by extensive sample preparation procedures that are performed in a laboratory. Analysis is typically conducted by injecting a liquid or gas sample...Alfentanil, Remifentanil , Sufentanil, and Carfentanil) in a laboratory. (5) Quantitatively determine a maximum temperature ramping rate at which the LTM...RHT Column combined with a GC-MS can separate and analyze a mixture of non- traditional CWAs (i.e. Fentanyl, Alfentanil, Remifentanil , Sufentanil

Development of a passive doas system to retrieve atmospheric pollution columns in the 200 to 355 nm region.

PubMed

Mejía, Rubén Galicia; Vázquez, Josémanueldelarosa; Isakina, Suren Stolik; García, Edgard Moreno; Iglesias, Gustavo Sosa

2013-01-08

In recent years several techniques have been developed to measure and monitor the pollution of the air. Among these techniques, remote sensing using optical methods stands out due to several advantages for air quality control applications. A Passive Differential Optical Absorption Spectroscopy system that uses the ultraviolet region from 200 to 355 nm of the solar radiation is presented. The developed system is portable; therefore it is practical for real time and in situ measurements. The enhanced wavelength range of the system is intended to detect the ultraviolet light penetration in the Mexican Valley considering the solar zenith angle and the altitude. The system was applied to retrieve atmospheric SO2 columns emitted either by anthropogenic (power plant) or natural sources (volcano), reaching a detection limit of about 1 ppm. The measurement of the penetrating solar radiation on the earth surface at the UVC range is presented and the possibility to measure pollution traces of some contaminants as O3, NO2 and aromatic compounds in real time and in situ in the ultraviolet region is discussed.

Development of a passive doas system to retrieve atmospheric pollution columns in the 200 to 355 nm region

PubMed Central

2013-01-01

In recent years several techniques have been developed to measure and monitor the pollution of the air. Among these techniques, remote sensing using optical methods stands out due to several advantages for air quality control applications. A Passive Differential Optical Absorption Spectroscopy system that uses the ultraviolet region from 200 to 355 nm of the solar radiation is presented. The developed system is portable; therefore it is practical for real time and in situ measurements. The enhanced wavelength range of the system is intended to detect the ultraviolet light penetration in the Mexican Valley considering the solar zenith angle and the altitude. The system was applied to retrieve atmospheric SO2 columns emitted either by anthropogenic (power plant) or natural sources (volcano), reaching a detection limit of about 1 ppm. The measurement of the penetrating solar radiation on the earth surface at the UVC range is presented and the possibility to measure pollution traces of some contaminants as O3, NO2 and aromatic compounds in real time and in situ in the ultraviolet region is discussed. PMID:23369629

Analysis of perfluorinated carboxylic acids in soils II: optimization of chromatography and extraction.

PubMed

Washington, John W; Henderson, W Matthew; Ellington, J Jackson; Jenkins, Thomas M; Evans, John J

2008-02-15

With the objective of detecting and quantitating low concentrations of perfluorinated carboxylic acids (PFCAs), including perfluorooctanoic acid (PFOA), in soils, we compared the analytical suitability of liquid chromatography columns containing three different stationary phases, two different liquid chromatography-tandem mass spectrometry (LC/MS/MS) systems, and eight combinations of sample-extract pretreatments, extractions and cleanups on three test soils. For the columns and systems we tested, we achieved the greatest analytical sensitivity for PFCAs using a column with a C(18) stationary phase in a Waters LC/MS/MS. In this system we achieved an instrument detection limit for PFOA of 270 ag/microL, equating to about 14 fg of PFOA on-column. While an elementary acetonitrile/water extraction of soils recovers PFCAs effectively, natural soil organic matter also dissolved in the extracts commonly imparts significant noise that appears as broad, multi-nodal, asymmetric peaks that coelute with several PFCAs. The intensity and elution profile of this noise is highly variable among soils and it challenges detection of low concentrations of PFCAs by decreasing the signal-to-noise contrast. In an effort to decrease this background noise, we investigated several methods of pretreatment, extraction and cleanup, in a variety of combinations, that used alkaline and unbuffered water, acetonitrile, tetrabutylammonium hydrogen sulfate, methyl-tert-butyl ether, dispersed activated carbon and solid-phase extraction. For the combined objectives of complete recovery and minimization of background noise, we have chosen: (1) alkaline pretreatment; (2) extraction with acetonitrile/water; (3) evaporation to dryness; (4) reconstitution with tetrabutylammonium-hydrogen-sulfate ion-pairing solution; (5) ion-pair extraction to methyl-tert-butyl ether; (6) evaporation to dryness; (7) reconstitution with 60/40 acetonitrile/water (v/v); and (8) analysis by LC/MS/MS. Using this method, we detected in all three of our test soils, endogenous concentrations of all of our PFCA analytes, C(6) through C(10)-the lowest concentrations being roughly 30 pg/g of dry soil for perfluorinated hexanoic and decanoic acids in an agricultural soil.

[Detection of rifampicin concentration in cerebrospinal fluid by online enrichment and restricted-access media coupled with high-performance liquid chromatography].

PubMed

Yang, Xiaoping; Zhang, Xiaohui; Huang, Yanping; Wang, Rong; Xia, Hua; Li, Wenbin; Guo, YouMin

2015-11-01

To establish a method for detecting rifampicin in human cerebrospinal fluid (CSF) with restricted access media coupled with high-performance liquid chromatography that allows online direct sample injection and enrichment. We used the column of restricted access media as the pre-treatment column and a C18 column as the analytical column. The mobile phase of pre-treatment column was water-methanol (95:5,V/V) and the flow rate was 1 mL/min; the mobile phase of the analytical column was methanol-acetonitrile-10 mmol/L ammonuium acetate (volume ratio of 60:5:35). The detection wavelength was 254 nm and the column temperature was set at 25 degrees celsius;. For an injection volume of 100 µL, the peak area of rifampicin was 5.33 times that for an injection volume of 20 µL, and the limit of detection was effectively improved. The calibration curve showed an excellent linear relationship (r=0.9997) between rifampicin concentrations and peak areas within the concentration range of 0.25 to 8 µg/mL in CSF. The limits of detection and quantification was 0.07 µg/mL and 0.25 µg/mL, respecetively, with intra-day and inter-day assay precisions and relative standard deviation (RSD%) all below 5%. The recoveries of rifampicin at 3 blank spiked levels (low, medium, and high) ranged from 87.69% to 102.11%. In patients taking oral rifampicin at the dose of 10 mg/kg, the average rifampicin concentration was 0.29 in the CSF at 2 h after medication. The method we established is simple and fast for detecting rifampicin in CSF and allows direct online injection and enrichment with good detection precisions and accuracies.

Design of a portable gas chromatography with a conducting polymer nanocomposite detector device and a method to analyze a gas mixture.

PubMed

Pirsa, Sajad

2017-04-01

A portable chromatography device and a method were developed to analyze a gas mixture. The device comprises a chromatographic column for separating components of a sample of the gas mixture. It has an air pump coupled to the inlet of a chromatographic column for pumping air and an injector coupled to the inlet of chromatographic column for feeding the sample using the air as a carrier gas. A detector is arranged downstream from and coupled to the outlet of the chromatographic column. The detector is a nanostructure semiconductive microfiber. The device further comprises an evaluation unit arranged and configured to evaluate each detected component to determine the concentration. The designed portable system was used for simultaneous detection of amines. The possibility of applying dispersive liquid-liquid microextraction for the determination of analytes in trace levels is demonstrated. The reproducibility of this method is acceptable, and good standard deviations were obtained. The relative standard deviation value is less than 6% for all analytes. Finally, the method was successfully applied to the extraction and determination of analytes in water samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Real-time system for imaging and object detection with a multistatic GPR array

DOEpatents

Paglieroni, David W; Beer, N Reginald; Bond, Steven W; Top, Philip L; Chambers, David H; Mast, Jeffrey E; Donetti, John G; Mason, Blake C; Jones, Steven M

2014-10-07

A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

Isoelectric focusing of proteins and peptides

NASA Technical Reports Server (NTRS)

Egen, N.

1979-01-01

Egg-white solution was chosen as the reference solution in order to assess the effects of operational parameters (voltage, flow rate, ampholine pH range and concentration, and protein concentration) of the RIEF apparatus on protein resolution. Topics of discussion include: (1) comparison of RIEF apparatus to conventional IEF techniques (column and PAG) with respect to resolution and throughput; (2) peptide and protein separation (AHF, Thymosin - Fraction 5, vasoactive peptide, L-asparaginase and ACP); and (3) detection of peptides - dansyl derivatives of amino acids and peptides, post-focusing fluorescent labeling of amino acids, peptides and proteins, and ampholine extraction from focused gels.

Determination of folates by HPLC-chemiluminescence using a ruthenium(II)-cerium(IV) system, and its application to pharmaceutical preparations and supplements.

PubMed

Ikeda, Rie; Ichiyama, Kosuke; Tabuchi, Naoto; Wada, Mitsuhiro; Kuroda, Naotaka; Nakashima, Kenichiro

2014-11-01

A chemiluminescence (CL) reaction of folic acid (FA) with ruthenium (II) and cerium (IV) was applied to quantify FA-related compounds such as FA, dihydrofolic acid, tetrahydrofolic acid, 5-methyltetrahydrofolic acid, 5-formyltetrahydrofolic acid and methotrexate (MTX). Among the FAs, 5-methyltetrahydrofolic acid provided the highest CL intensity. HPLC-CL detection of FA was applied to quantify FA in pharmaceutical preparations and supplements. Analytical samples were separated on a semi-micro ODS column with a mixture of 20 mM phosphate buffer (pH 5.7) and acetonitrile (94 : 6, v/v %). The separated samples were mixed with a post-column CL reagent consisting of 1.5 mM Ru(bipy)3 (2+) and 1.0 mM Ce(SO4)2 , then the generated CL was monitored. The calibration range for FA was 10-100 μM and the limit of detection was 1.34 μM (signal-to-noise ratio of 3). Repeatabilities were 4.2, 4.6 and 5.0 RSD% (10, 25, 50 μM), and the recoveries for FA supplement, vitamin B complex supplement and FA-containing medication (tablet) were 102.4 ± 10.5, 103.3 ± 13.3 and 100.3 ± 8.5%, respectively. The described method is robust against changes in the chromatographic parameters of ± 3.3 or ± 1.5%. The measured FA content corresponded well to the labeled content of FA-containing products (100.6-104.9%), demonstrating the precision and accuracy of this method for the evaluation of FA pharmaceutical preparations. Copyright © 2014 John Wiley & Sons, Ltd.

Estimating phosphorus concentrations following alum treatment using apparent settling velocity

USGS Publications Warehouse

Panuska, John; Robertson, Dale M.

2009-01-01

he apparent settling velocity (Vs) is a term used in empirical, steady-state, mass-balance lake models to represent the net phosphorus flux from the water column. The Vollenweider (1969) mixed-reactor lake model was rearranged and used to calculate Vs values for total phosphorus (TP) for three lakes treated with alum to reduce the internal flux of P to the water column (Delavan Lake, Wisconsin; Lake Morey, Vermont; and West Twin Lake, Ohio). An analysis of Vs values was conducted using data from these three lakes for both the pre- and post-alum treated conditions. Analysis of Vs values for both the pre- and post-alum conditions in Lake Morey and West Twin Lake resulted in a post-treatment mean Vs value of 7 ± 2.0 m·yr−1. The effect of the alum treatment, although short-lived in Delavan Lake, resulted in a mean post-treatment Vs value of 3.4 ± 0.3 m·yr−1. The consistency in the post-treatment Vs values in Lake Morey and West Twin Lake is used to demonstrate a predictive analysis method for water column TP concentrations in lakes following a successful treatment of the anoxic sediment area with alum. Additional pre- and post-alum in-lake and watershed loading data are needed to advance this concept into a management model.

NASA combined file postings statistics based on NASA thesaurus, Jan. 1968 - July 1988

NASA Technical Reports Server (NTRS)

1988-01-01

The NASA Combined File Postings Statistics is published semiannually (January and July). This alphabetical listing of postable subject terms contained in the NASA Thesaurus is used to display the numbers of postings (documents) indexed by each subject term from 1968 to date. The postings total per term are separated by announcement or other media into STAR, IAA, NLN, and OTHER columnar entries covering the NASA document collection (1968 to date). Nearly 594,000 book postings for NALNET Books held by NASA libraries are now included under the NLN column. CSTAR postings as well as some previously unreported series are now listed under the other column. File postings statistics for the Alternate Data Base covering the NASA collection from 1962 through 1967 were published on a one-time basis in September 1975. Subject terms for the Alternate Data Base are derived from the Subject Authority List, reprinted in 1985, which is available on request. The distribution of 16,919,195 postings among the 17,105 Thesaurus terms is tabulated on the last page of Combined File Postings Statistics.

Preparative electrophoresis with on-column optical fiber monitoring and direct elution into a minimized volume.

PubMed

Jackson, George W; Willson, Richard

2005-11-01

A "column-format" preparative electrophoresis device which obviates the need for gel extraction or secondary electro-elution steps is described. Separated biomolecules are continuously detected and eluted directly into a minimal volume of free solution for subsequent use. An optical fiber allows the species of interest to be detected just prior to elution from the gel column, and a small collection volume is created by addition of an ion-exchange membrane near the end of the column.

Mini-column assay for rapid detection of malachite green in fish.

PubMed

Shalaby, Ali R; Emam, Wafaa H; Anwar, Mervat M

2017-07-01

A simple, rapid and economical mini-column method for detecting malachite green (MG) residue in fish was developed. The method used a column with 2mm ID that was tightly packed with silica gel followed by alumina. Detection of MG was performed by viewing the developed mini-column at visible light by naked eye; where MG was seen as compact green band at the confluence of the silica gel layer with alumina layer. The limit of detection of the assay was 2ng which conform the minimum required performance limit (MRPL). Evaluation utility of the method indicated that all blank and spiked samples at levels below MRPL were assessed as accepted. The intensity of the green band increased whenever MG level in the extract increased; indicated that suggested mini-column technique could be used for semi-quantitative determination of MG in fish samples. The method can be used to select the questionable samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

Microfluidic integration of parallel solid-phase liquid chromatography.

PubMed

Huft, Jens; Haynes, Charles A; Hansen, Carl L

2013-03-05

We report the development of a fully integrated microfluidic chromatography system based on a recently developed column geometry that allows for robust packing of high-performance separation columns in poly(dimethylsiloxane) microfluidic devices having integrated valves made by multilayer soft lithography (MSL). The combination of parallel high-performance separation columns and on-chip plumbing was used to achieve a fully integrated system for on-chip chromatography, including all steps of automated sample loading, programmable gradient generation, separation, fluorescent detection, and sample recovery. We demonstrate this system in the separation of fluorescently labeled DNA and parallel purification of reverse transcription polymerase chain reaction (RT-PCR) amplified variable regions of mouse immunoglobulin genes using a strong anion exchange (AEX) resin. Parallel sample recovery in an immiscible oil stream offers the advantage of low sample dilution and high recovery rates. The ability to perform nucleic acid size selection and recovery on subnanogram samples of DNA holds promise for on-chip genomics applications including sequencing library preparation, cloning, and sample fractionation for diagnostics.

Sequential injection system with in-line solid phase extraction and soil mini-column for determination of zinc and copper in soil leachates.

PubMed

Paluch, Justyna; Mesquita, Raquel B R; Cerdà, Víctor; Kozak, Joanna; Wieczorek, Marcin; Rangel, António O S S

2018-08-01

A sequential injection (SI) system equipped with in-line solid phase extraction column and in-line soil mini-column is proposed for determination of zinc and copper in soil leachates. The spectrophotometric determination (560 nm) is based on the reaction of both analytes with 1-(2-Pyridylazo)-2-naphthol (PAN). Zinc is determined after retaining copper on a cationic resin (Chelex100) whereas copper is determined from the difference of the absorbance measured for both analytes, introduced into the system with the use of a different channel, and zinc absorbance. The influence of several potential interferences was studied. Using the developed method, zinc and copper were determined within the concentration ranges of 0.005-0.300 and 0.011-0.200 mg L -1 , and with a relative standard deviation lower than 6.0% and 5.1%, respectively. The detection limits are 1.4 and 3.0 µg/L for determination of zinc and copper, respectively. The developed SI method was verified by the determination of both analytes in synthetic and certified reference materials of water samples, and applied to the determination of the analytes in rain water and soil leachates from laboratory scale soil core column and in-line soil mini-column. Copyright © 2018 Elsevier B.V. All rights reserved.

Achiral-chiral two-dimensional chromatography of free amino acids in milk: A promising tool for detecting different levels of mastitis in cows.

PubMed

Ianni, Federica; Sardella, Roccaldo; Lisanti, Antonella; Gioiello, Antimo; Cenci Goga, Beniamino Terzo; Lindner, Wolfgang; Natalini, Benedetto

2015-12-10

In two-dimensional HPLC (2D-HPLC) "heart-cut" applications, two columns are connected in series via a switching valve and volume fractions from the "primary" column are re-injected on the "secondary" column. The heart-cut 2D-HPLC system here described was implemented by connecting a reversed-phase (RP) column (first dimension) to a chiral column (second dimension) containing a quinidine-based chiral stationary phase. The system was used to evaluate the change in the enantiomeric excess value of dansylated (Dns) amino acids (AAs) in milk samples from two cows with different "California Mastitis Test" scores: negative test for sample 1, positive for sample 2. Apart from the co-elution of Dns-Arg/Dns-Gly and the reduced chemoselectivity for Dns-Leu/Dns-allo-Ile, the optimized achiral RP method distinguished the remaining standard Dns-AAs. Dns-AAs were identified in the chromatograms of the real samples, and in higher concentration Dns-Ala, Dns-Arg, Dns-Asp, Dns-Glu, Dns-Ile, Dns-Leu, Dns-Phe and Dns-Val. Except Dns-Arg, the chiral column enabled the RP enantioseparation of all the other compounds (α and RS values up to 1.65 and 8.63, respectively, for Dns-Phe). In sample 2, the amounts of Dns-d-AAs were rather elevated, in particular for Dns-Ala and Dns-Asp. Instead, for sample 1, D-isomers were detected for Dns-Ala, Dns-Glu and Dns-Leu. The proposed 2D-HPLC method could be useful for the identification of clinical mastitis difficult to be diagnosed. Moreover, the eventual progressive reduction of D-AAs levels with the degree of sub-clinical mastitis could allow the building of mathematical models to use for the diagnosis of early stages of mastitis. Copyright © 2014 Elsevier B.V. All rights reserved.

An automated online turboflow cleanup LC/MS/MS method for the determination of 11 plasticizers in beverages and milk.

PubMed

Ates, Ebru; Mittendorf, Klaus; Senyuva, Hamide

2013-01-01

An automated sample preparation technique involving cleanup and analytical separation in a single operation using an online coupled TurboFlow (RP-LC system) is reported. This method eliminates time-consuming sample preparation steps that can be potential sources for cross-contamination in the analysis of plasticizers. Using TurboFlow chromatography, liquid samples were injected directly into the automated system without previous extraction or cleanup. Special cleanup columns enabled specific binding of target compounds; higher MW compounds, i.e., fats and proteins, and other matrix interferences with different chemical properties were removed to waste, prior to LC/MS/MS. Systematic stepwise method development using this new technology in the food safety area is described. Selection of optimum columns and mobile phases for loading onto the cleanup column followed by transfer onto the analytical column and MS detection are critical method parameters. The method was optimized for the assay of 10 phthalates (dimethyl, diethyl, dipropyl, butyl benzyl, diisobutyl, dicyclohexyl, dihexyl, diethylhexyl, diisononyl, and diisododecyl) and one adipate (diethylhexyl) in beverages and milk.

Evaluation of an International Pharmacopoeia method for the analysis of nelfinavir mesilate by liquid chromatography.

PubMed

Yekkala, Raja Satyanarayana; Vandenwayenberg, Stephanie; Hoogmartens, Jos; Adams, Erwin

2006-11-17

A gradient LC method for the determination of related substances in nelfinavir mesilate (NFVM) has been recently published in the International Pharmacopoeia. The method uses a base deactivated reversed phase C18 column (25 cm x 4.6 mm I.D.), 5 microm kept at a temperature of 35 degrees C. The mobile phases consist of acetonitrile, methanol, phosphate buffer pH 3.4 and water. The flow rate is 1.0 ml/min. UV detection is performed at 225 nm. A system suitability test (SST) is described to govern the quality of the separation. The separation towards NFVM components was investigated on 18 C18 columns and correlation was made with the column classification system developed in our laboratory. The method was evaluated using a Hypersil BDS C18 column (25 cm x 4.6 mm I.D.), 5 microm. A two level fractional factorial design was applied to examine the robustness of the method. The method shows good selectivity, precision, linearity and sensitivity. Seven commercial samples were examined using this method.

High Strength Concrete Columns under Axial Compression Load: Hybrid Confinement Efficiency of High Strength Transverse Reinforcement and Steel Fibers

PubMed Central

Perceka, Wisena; Liao, Wen-Cheng; Wang, Yo-de

2016-01-01

Addition of steel fibers to high strength concrete (HSC) improves its post-peak behavior and energy absorbing capability, which can be described well in term of toughness. This paper attempts to obtain both analytically and experimentally the efficiency of steel fibers in HSC columns with hybrid confinement of transverse reinforcement and steel fibers. Toughness ratio (TR) to quantify the confinement efficiency of HSC columns with hybrid confinement is proposed through a regression analysis by involving sixty-nine TRs of HSC without steel fibers and twenty-seven TRs of HSC with hybrid of transverse reinforcement and steel fibers. The proposed TR equation was further verified by compression tests of seventeen HSC columns conducted in this study, where twelve specimens were reinforced by high strength rebars in longitudinal and transverse directions. The results show that the efficiency of steel fibers in concrete depends on transverse reinforcement spacing, where the steel fibers are more effective if the spacing transverse reinforcement becomes larger in the range of 0.25–1 effective depth of the section column. Furthermore, the axial load–strain curves were developed by employing finite element software (OpenSees) for simulating the response of the structural system. Comparisons between numerical and experimental axial load–strain curves were carried out. PMID:28773391

Development and validation of a high-performance liquid chromatography method with post-column derivatization for the detection of aflatoxins in cereals and grains.

PubMed

Asghar, Muhammad Asif; Iqbal, Javed; Ahmed, Aftab; Khan, Mobeen Ahmed; Shamsuddin, Zuzzer Ali; Jamil, Khalid

2016-06-01

A novel, reliable and rapid high-performance liquid chromatography (HPLC) method with post-column derivatization was developed and validated. The HPLC method was used for the simultaneous determination of aflatoxin B1 (AFB1), B2 (AFB2), G1 (AFG1) and G2 (AFG2) in various cereals and grains. Samples were extracted with 80:20 (v/v) methanol:water and purified using C18 (40-63 μm) solid-phase extraction cartridges. AFs were separated using a LiChroCART-RP-18 (5 μm, 250 × 4.0 mm(2)) column. The mobile phase consisted of methanol:acetonitrile:buffer (17.5:17.5:65 v/v) (pH 7.4) delivered at the flow rate of 1.0 mL min(-1) The fluorescence of each AF was detected at λex = 365 nm and λem = 435 nm. All four AFs were properly resolved within the total run time of 20 min. The established method was extensively validated as a final verification of the method development by the evaluation of selectivity (AFB1, AFB2, AFG1 and AFG2), linearity (R(2) ≥ 0.9994), precision (average SD ≤ 2.79), accuracy (relative mean error ≤ -5.51), robustness (p < 0.0080), ruggedness (p < 0.0100) and average recoveries (89.2-97.8%). The limits of quantification of AFB1, AFB2, AFG1 and AFG2 were 0.080, 0.073, 0.062 and 0.066 ng g(-1), respectively. Finally, the developed method was applied for the analysis of AFs in 45 samples comprising rice (n = 20), wheat (n = 15) and maize (n = 10). The results showed that 65% of rice, 20% of wheat and 80% of maize samples were found contaminated with AFs. Thus, according to the achieved results, it is suggested that the newly developed HPLC method could be effectively applied for the routine analysis of the AFs in different cereals and grains. © The Author(s) 2014.

26 CFR 1.167(l)-2 - Public utility property; election as to post-1969 property representing growth in capacity.

Code of Federal Regulations, 2011 CFR

2011-04-01

... Capacity as of Jan. 1, 1970, plus amounts in column 7 for years prior to the year for which determination is being made. 2 Column 6 minus column 5. (v) The qualified portion of the basis for depreciation (as defined in section 167(g)) of each asset or group of assets (if group or composite accounting is used by...

26 CFR 1.167(l)-2 - Public utility property; election as to post-1969 property representing growth in capacity.

Code of Federal Regulations, 2012 CFR

2012-04-01

... Capacity as of Jan. 1, 1970, plus amounts in column 7 for years prior to the year for which determination is being made. 2 Column 6 minus column 5. (v) The qualified portion of the basis for depreciation (as defined in section 167(g)) of each asset or group of assets (if group or composite accounting is used by...

26 CFR 1.167(l)-2 - Public utility property; election as to post-1969 property representing growth in capacity.

Code of Federal Regulations, 2014 CFR

2014-04-01

... Capacity as of Jan. 1, 1970, plus amounts in column 7 for years prior to the year for which determination is being made. 2 Column 6 minus column 5. (v) The qualified portion of the basis for depreciation (as defined in section 167(g)) of each asset or group of assets (if group or composite accounting is used by...

26 CFR 1.167(l)-2 - Public utility property; election as to post-1969 property representing growth in capacity.

Code of Federal Regulations, 2013 CFR

2013-04-01

... Capacity as of Jan. 1, 1970, plus amounts in column 7 for years prior to the year for which determination is being made. 2 Column 6 minus column 5. (v) The qualified portion of the basis for depreciation (as defined in section 167(g)) of each asset or group of assets (if group or composite accounting is used by...

26 CFR 1.167(l)-2 - Public utility property; election as to post-1969 property representing growth in capacity.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Capacity as of Jan. 1, 1970, plus amounts in column 7 for years prior to the year for which determination is being made. 2 Column 6 minus column 5. (v) The qualified portion of the basis for depreciation (as defined in section 167(g)) of each asset or group of assets (if group or composite accounting is used by...

Determination of 3-hydroxypropylmercapturic acid in urine by three column-switching high-performance liquid chromatography with electrochemical detection using a diamond electrode.

PubMed

Higashi, Kyohei; Shibasaki, Mana; Kuni, Kyoshiro; Uemura, Takeshi; Waragai, Masaaki; Uemura, Kenichi; Igarashi, Kazuei; Toida, Toshihiko

2017-09-29

A three column-switching high-performance liquid chromatography (HPLC) using an electrochemical detector (ECD) equipped with a diamond electrode was established to determine 3-hydroxypropylmercapturic acid (3-HPMA) in urine. An extracted urine sample was consecutively fractionated using a strong anion-exchange column (first column) and a C8 column (second column) via a switching valve before application on an Octa Decyl Silyl (ODS) column (third column), followed by ECD analysis. The% recovery of 3-HPMA standard throughout the three-column process and limit of detection (LOD) were 94±1% and 0.1pmol, respectively. A solid phase extraction step is required for the sensitive analysis of 3-HPMA in urine by column-switching HPLC-ECD despite a decreased% recovery (55%) of urine sample spiked with 100pmol of 3-HPMA. To test the utility of our column-switching HPLC-ECD method, 3-HPMA levels of 27 urine samples were determined, and the correlation between HPLC-ECD and LC-Electrospray ionization (ESI)-MS/MS method was examined. As a result, the median values of μmol 3-HPMA/g Creatinine (Cre) in urine obtained by column-switching HPLC-ECD and LC-MS/MS were 2.19±2.12μmol/g Cre and 2.13±3.38μmol/g Cre, respectively, and the calibration curve (y=1.5171x-1.007) exhibited good linearity within a defined range (r 2 =0.907). These results indicate that the combination of column-switching HPLC and ECD is a powerful tool for the specific, reliable detection of 3-HPMA in urine. Copyright © 2017 Elsevier B.V. All rights reserved.

40 CFR 61.242-2 - Standards: Pumps.

Code of Federal Regulations, 2011 CFR

2011-07-01

... fluid degassing reservoir that is routed to a process or fuel gas system or connected by a closed-vent..., is not in VOC service. (3) Each barrier fluid system is equipped with a sensor that will detect... employ a gas chromatography column to limit the response of the monitor to VHAP, at the option of the...

40 CFR 61.242-2 - Standards: Pumps.

Code of Federal Regulations, 2010 CFR

2010-07-01

... fluid degassing reservoir that is routed to a process or fuel gas system or connected by a closed-vent..., is not in VOC service. (3) Each barrier fluid system is equipped with a sensor that will detect... employ a gas chromatography column to limit the response of the monitor to VHAP, at the option of the...

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.

Separation methods applicable to urinary creatine and creatinine.

PubMed

Smith-Palmer, Truis

2002-12-05

Urinary creatinine has been analyzed for many years as an indicator of glomerular filtration rate. More recently, interest in studying the uptake of creatine as a result of creatine supplementation, a practice increasingly common among bodybuilders and athletes, has lead to a need to measure urinary creatine concentrations. Creatine levels are of the same order of magnitude as creatinine levels when subjects have recently ingested creatine, while somewhat elevated urinary creatine concentrations in non-supplementing subjects can be an indication of a degenerative disease of the muscle. Urinary creatine and creatinine can be analyzed by HPLC using a variety of columns. Detection methods include absorption, fluorescence after post-column derivatization, and mass spectrometry, and some methods have been automated. Capillary zone electrophoresis and micellar electrokinetic capillary chromatography have also been used to analyze urinary creatine and creatinine. Creatine and creatinine have also been analyzed in serum and tissue using HPLC and CE, and many of these separations could also be applicable to urinary analysis.

A simple and rapid technique for radiochemical separation of iodine radionuclides from irradiated tellurium using an activated charcoal column.

PubMed

Chattopadhyay, Sankha; Saha Das, Sujata

2009-10-01

A simple and inexpensive method for the separation of medically useful no-carrier-added (nca) iodine radionuclides from bulk amounts of irradiated tellurium dioxide (TeO(2)) target was developed. The beta(-) emitting (131)I radionuclide, produced by the decay of (131)Te through the (nat)Te(n, gamma)(131)Te nuclear reaction, was used for standardization of the radiochemical separation procedure. The radiochemical separation was performed by precipitation followed by column (activated charcoal) chromatography. Quantitative post-irradiation recovery of the TeO(2) target material (98-99%), in a form suitable for reuse in future irradiations, was achieved. The overall radiochemical yield for the complete separation of (131)I was 75-85% (n=8). The separated nca (131)I was of high, approximately 99%, radionuclidic and radiochemical purities and did not contain detectable amounts of the target material. This method can be adopted for the radiochemical separation of other different iodine radionuclides produced from tellurium matrices through cyclotron as well as reactor irradiation.

Determination of penicillamine in pharmaceuticals and human plasma by capillary electrophoresis with in-column fiber optics light-emitting diode induced fluorescence detection.

PubMed

Yang, Xiupei; Yuan, Hongyan; Wang, Chunling; Su, Xiaodong; Hu, Li; Xiao, Dan

2007-10-18

In this paper, a capillary electrophoresis (CE) system with in-column fiber optics light-emitting diode (LED) induced fluorescence detection was developed for the determination of penicillamine (PA). The influence of buffer concentration, buffer pH, applied voltage and injection time was systematically investigated. Optimum separation conditions were obtained with 10 mM borate buffer at pH 9.1, applied voltage 20 kV and 8 s hydrodynamic injection at 30 mbar. The detection system displayed linear dynamic range from 3.2 x 10(-7) to 4.8 x 10(-5) mol L(-1) with a correlation coefficient of 0.9991 and good repeatability (R.S.D.=2.46%). The method was applied to the determination of PA in commercial tablets and human plasma, which the recoveries of standard PA added to tablets and human plasma sample were found to be in the range of 96.26-102.68 and 91.10-99.35%, respectively. The proposed method is cheap, rapid, easy, and accurate, and can be successfully applied to the formulation analysis and bioanalysis.

Comprehensive Detection of Gas Plumes from Multibeam Water Column Images with Minimisation of Noise Interferences

PubMed Central

Zhao, Jianhu; Zhang, Hongmei; Wang, Shiqi

2017-01-01

Multibeam echosounder systems (MBES) can record backscatter strengths of gas plumes in the water column (WC) images that may be an indicator of possible occurrence of gas at certain depths. Manual or automatic detection is generally adopted in finding gas plumes, but frequently results in low efficiency and high false detection rates because of WC images that are polluted by noise. To improve the efficiency and reliability of the detection, a comprehensive detection method is proposed in this paper. In the proposed method, the characteristics of WC background noise are first analyzed and given. Then, the mean standard deviation threshold segmentations are respectively used for the denoising of time-angle and depth-angle images, an intersection operation is performed for the two segmented images to further weaken noise in the WC data, and the gas plumes in the WC data are detected from the intersection image by the morphological constraint. The proposed method was tested by conducting shallow-water and deepwater experiments. In these experiments, the detections were conducted automatically and higher correct detection rates than the traditional methods were achieved. The performance of the proposed method is analyzed and discussed. PMID:29186014

Natural hydrocarbon seeps observation with underwater gliders and UV fluorescence sensor

NASA Astrophysics Data System (ADS)

Rochet, V.

2016-02-01

Hydrocarbons may leak to the near-surface from subsurface accumulations, from mature source rock, or by buoyancy along major cross-strata routes. The presence of migrating near-surface hydrocarbons can provide strong evidence for the presence of a working petroleum system, as well as valuable information on source, maturity, and migration pathways. Detection and characterization of hydrocarbons in the water column may then help to de-risk hydrocarbon plays at a very preliminary stage of an exploration program. In order to detect hydrocarbons in the water column, an underwater glider survey was conducted in an offshore frontier area. Driven by buoyancy variation, underwater gliders enable collecting data autonomously along the water column for weeks to months. Underwater gliders are regularly piloted from shore by satellite telemetry and do not require a surface supervising vessel resulting in substantial operational costs savings. The data compiled, over 700m depth of the water column, included temperature, salinity, pressure, dissolved oxygen and hydrocarbon components (phenanthrene and naphthalene) measured by "MINIFLUO" sensors to particularly target representative crude oil compounds Two gliders were deployed at sea, one from coast in shallow water and the other one offshore on the survey area. Both accurately squared the survey area following pre-defined lines and cross lines. Data files were transmitted by satellite telemetry in near real time during the performance of the mission for real time observations and appropriate re-positioning of the gliders. Using rechargeable underwater gliders increased reliability reducing the risk of leakage and associated logistics during operation at sea. Despite strong evidences of seabed seepages such as pockmarks, faults, etc, over the area of interest, no hydrocarbon indices were detected in the water column, which was confirmed later by seabed sample analysis. The use of glider platforms for hydrocarbon detection has been demonstrated, and they can nowadays be utilized as a proven and efficient technology for hydrocarbon exploration purposes beyond their classical oceanology uses.

X ray spectra of cataclysmic variables

NASA Technical Reports Server (NTRS)

Patterson, Joseph; Halpern, Jules

1990-01-01

X ray spectral parameters of cataclysmic variables observed with the 'Einstein' imaging proportional counter were determined by fitting an optically thin, thermal bremsstrahlung spectrum to the raw data. Most of the sources show temperatures of order a few keV, while a few sources exhibit harder spectra with temperatures in excess of 10 keV. Estimated 0.1 to 3.5 keV luminosities are generally in the range from 10(exp 30) to 10(exp 32) erg/sec. The results are consistent with the x rays originating in a disk/white dwarf boundary layer of non-magnetic systems, or in a hot, post-shock region in the accretion column of DQ Her stars, with a negligible contribution from the corona of the companion. In a few objects column densities were found that are unusually high for interstellar material. It was suggested that the absorption occurs in the system itself.

Flow-Cell-Induced Dispersion in Flow-through Absorbance Detection Systems: True Column Effluent Peak Variance.

PubMed

Dasgupta, Purnendu K; Shelor, Charles Phillip; Kadjo, Akinde Florence; Kraiczek, Karsten G

2018-02-06

Following a brief overview of the emergence of absorbance detection in liquid chromatography, we focus on the dispersion caused by the absorbance measurement cell and its inlet. A simple experiment is proposed wherein chromatographic flow and conditions are held constant but a variable portion of the column effluent is directed into the detector. The temporal peak variance (σ t,obs 2 ), which increases as the flow rate (F) through the detector decreases, is found to be well-described as a quadratic function of 1 / F . This allows the extrapolation of the results to zero residence time in the detector and thence the determination of the true variance of the peak prior to the detector (this includes contribution of all preceding components). This general approach should be equally applicable to detection systems other than absorbance. We also experiment where the inlet/outlet system remains the same but the path length is varied. This allows one to assess the individual contributions of the cell itself and the inlet/outlet system.to the total observed peak. The dispersion in the cell itself has often been modeled as a flow-independent parameter, dependent only on the cell volume. Except for very long path/large volume cells, this paradigm is simply incorrect.

Preparation of clenbuterol imprinted monolithic polymer with hydrophilic outer layers by reversible addition-fragmentation chain transfer radical polymerization and its application in the clenbuterol determination from human serum by on-line solid-phase extraction/HPLC analysis.

PubMed

Li, Xiaobing; Zhou, Man; Turson, Mamat; Lin, Shen; Jiang, Ping; Dong, Xiangchao

2013-05-21

A novel imprinted monolithic material with the ability of protein exclusion was developed for the selective extraction of clenbuterol (CLE) from biological samples by direct injection in the HPLC analysis. The material has an imprinted inner structure and hydrophilic outer layer. The reversible addition-fragmentation chain transfer (RAFT) polymerization was employed in the material preparation by a two-step procedure. In the first step, clenbuterol imprinted monolithic polymer was synthesized by combining the molecular imprinting and the RAFT polymerization techniques. The resulting monolithic polymer has a RAFT chain transfer agent (trithioester groups) in its structure, which was used to graft poly(glycerol mono-methacrylate) [pGMMA] in the second step by post-RAFT polymerization. The hydrophilic pGMMA layers grafted on the surface of the imprinted monolith created barriers for protein diffusion. More than 90% of bovine serum albumin can be excluded from the pGMMA coated monolithic column. Meanwhile the clenbuterol was retained selectively with a large retention factor. The result indicated that the column, denoted as RA-MIM, has both the merits of a molecularly imprinted polymer and restricted access material. By using RA-MIM as the solid-phase extraction pre-column, an on-line column-switching HPLC method for the determination of clenbuterol in human serum has been established and validated. The recoveries of clenbuterol from the serum were 87.3-96.9% in the spiked level 2-1000 ng mL(-1). Both good linearity (R = 0.999) and acceptable reproducibility (RSD < 7.0%) were obtained. The limit of detection and the limit of quantitation were 0.7 ng mL(-1) and 2.0 ng mL(-1) respectively, which is sensitive in terms of UV detection. The results have demonstrated that the RAFT polymerization can be used to synthesize bi-functional monolithic columns by using its living reaction property. The resulting RA-MIM in this research can be used for efficient clenbuterol determination by HPLC from biological samples.

Site-directed immobilization of a genetically engineered anti-methotrexate antibody via an enzymatically introduced biotin label significantly increases the binding capacity of immunoaffinity columns.

PubMed

Davenport, Kaitlynn R; Smith, Christopher A; Hofstetter, Heike; Horn, James R; Hofstetter, Oliver

2016-05-15

In this study, the effect of random vs. site-directed immobilization techniques on the performance of antibody-based HPLC columns was investigated using a single-domain camelid antibody (VHH) directed against methotrexate (MTX) as a model system. First, the high flow-through support material POROS-OH was activated with disuccinimidyl carbonate (DSC), and the VHH was bound in a random manner via amines located on the protein's surface. The resulting column was characterized by Frontal Affinity Chromatography (FAC). Then, two site-directed techniques were explored to increase column efficiency by immobilizing the antibody via its C-terminus, i.e., away from the antigen-binding site. In one approach, a tetra-lysine tail was added, and the antibody was immobilized onto DSC-activated POROS. In the second site-directed approach, the VHH was modified with the AviTag peptide, and a biotin-residue was enzymatically incorporated at the C-terminus using the biotin ligase BirA. The biotinylated antibody was subsequently immobilized onto NeutrAvidin-derivatized POROS. A comparison of the FAC analyses, which for all three columns showed excellent linearity (R(2)>0.999), revealed that both site-directed approaches yield better results than the random immobilization; the by far highest efficiency, however, was determined for the immunoaffinity column based on AviTag-biotinylated antibody. As proof of concept, all three columns were evaluated for quantification of MTX dissolved in phosphate buffered saline (PBS). Validation using UV-detection showed excellent linearity in the range of 0.04-12μM (R(2)>0.993). The lower limit of detection (LOD) and lower limit of quantification (LLOQ) were found to be independent of the immobilization strategy and were 40nM and 132nM, respectively. The intra- and inter-day precision was below 11.6%, and accuracy was between 90.7% and 112%. To the best of our knowledge, this is the first report of the AviTag-system in chromatography, and the first application of immunoaffinity chromatography for the analysis of MTX. Copyright © 2016 Elsevier B.V. All rights reserved.

Tropospheric ozone enhancement during post-harvest crop-residue fires at two downwind sites of the Indo-Gangetic Plain.

PubMed

Kumari, Sonal; Verma, Nidhi; Lakhani, Anita; Tiwari, Suresh; Kandikonda, Maharaj Kumari

2018-05-01

In the present study, surface ozone (O 3 ), nitrogen oxides (NO x ), and carbon monoxide (CO) levels were measured at two sites downwind of fire active region in the Indo-Gangetic Plain (IGP): Agra (27.16° N, 78.08° E) and Delhi (28.37° N, 77.12° E) to study the impact of post-harvest crop-residue fires. The study period was classified into two groups: Pre-harvest period and Post-harvest period. During the post-harvest period, an enhancement of 17.3 and 31.7 ppb in hourly averaged O 3 mixing ratios was observed at Agra and Delhi, respectively, under similar meteorological conditions. The rate of change of O 3 was also higher in the post-harvest period by 56.2% in Agra and 39.5% in Delhi. Relatively higher O 3 episodic days were observed in the post-harvest period. Fire hotspots detected by Moderate Resolution Imaging Spectroradiometer (MODIS) along with backward air-mass trajectory analysis suggested that the enhanced O 3 and CO levels at the study sites during the post-harvest period could be attributed to crop-residue burning over the North-West IGP (NW-IGP). Satellite observations of surface CO mixing ratios and tropospheric formaldehyde (HCHO) column also showed higher levels during the post-harvest period. Graphical abstract.

Radar signal pre-processing to suppress surface bounce and multipath

DOEpatents

Paglieroni, David W; Mast, Jeffrey E; Beer, N. Reginald

2013-12-31

A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes that return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

Spatially adaptive migration tomography for multistatic GPR imaging

DOEpatents

Paglieroni, David W; Beer, N. Reginald

2013-08-13

A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

Synthetic aperture integration (SAI) algorithm for SAR imaging

DOEpatents

Chambers, David H; Mast, Jeffrey E; Paglieroni, David W; Beer, N. Reginald

2013-07-09

A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

Zero source insertion technique to account for undersampling in GPR imaging

DOEpatents

Chambers, David H; Mast, Jeffrey E; Paglieroni, David W

2014-02-25

A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

Post-synthetic modification of MIL-101(Cr) with pyridine for high-performance liquid chromatographic separation of tocopherols.

PubMed

Yang, Fang; Yang, Cheng-Xiong; Yan, Xiu-Ping

2015-05-01

Effective separation of tocopherols is challenging and significant due to their structural similarity and important biological role. Here we report the post-synthetic modification of metal-organic framework (MOF) MIL-101(Cr) with pyridine for high-performance liquid chromatographic (HPLC) separation of tocopherols. Baseline separation of four tocopherols was achieved on a pyridine-grafted MIL-101(Cr) packed column within 10 min using hexane/isopropanol (96:4, v/v) as the mobile phase at a flow rate of 0.5 mL min(-1). The pyridine-grafted MIL-101(Cr) packed column gave high column efficiency (85,000 plates m(-1) for δ-tocopherol) and good precision (0.2-0.3% for retention time, 1.8-3.4% for peak area, 2.6-2.7% for peak height), and also offered much better performance than unmodified MIL-101(Cr) and commercial amino-bonded silica packed column for HPLC separation of tocopherols. The results not only show the promising application of pyridine-grafted MIL-101(Cr) as a novel stationary phase for HPLC separation of tocopherols, but also reveal a facile post-modification of MOFs to expand the application of MOFs in separation sciences. Copyright © 2015 Elsevier B.V. All rights reserved.

Two-dimensional gas chromatographic analysis of ambient light hydrocarbons.

PubMed

Liao, Wei-Chen; Ou-Yang, Cheng-Feng; Wang, Chieh-Heng; Chang, Chih-Chung; Wang, Jia-Lin

2013-06-14

Ambient level hydrocarbons lighter than C6 were analyzed by the Deans switch-modulated comprehensive two-dimensional gas chromatography (GC×GC) method with flame ionization detection (FID). A thermal desorption (TD) device built in-house connects the GC×GC system to pre-concentrate the target compounds at ambient levels prior to GC analysis. Because the conventional orthogonality based on polarity difference for normal GC×GC separation does not provide sufficient retention for the target compounds of extremely high volatility, the orthogonality of non-polar vs. adsorptive force was adopted instead. The system employed a 100% polydimethyl siloxane column serving as the first-dimension column to provide separation based on dispersive interaction, with a short PLOT column serving as the second-dimension column to provide the needed retention based on gas-solid adsorption interactions. The shortest possible length of the PLOT column was tested to minimize the modulation period (PM) and wraparound and, at the same time, to maintain the desired resolution. The tests led to the final optimal parameters of 1.1m for the PLOT column length, 9s for the PM, 0.013 for the modulation duty cycle (DC) and a modulation ratio (MR) of 3.7 with minimal wraparound. Important criteria for quality assurance of precision and linearity are reported. The low cost and ease of construction and operation make the in-house Deans switch TD-GC×GC-FID system practical and useful for the analysis of light hydrocarbons in urban or industrial environments. Copyright © 2013 Elsevier B.V. All rights reserved.

Multiple-channel ultra-violet absorbance detector for two-dimensional chromatographic separations.

PubMed

Lynch, Kyle B; Yang, Yu; Ren, Jiangtao; Liu, Shaorong

2018-05-01

In recent years, much research has gone into developing online comprehensive two-dimensional liquid chromatographic systems allowing for high peak capacities in comparable separation times to that of one-dimensional liquid chromatographic systems. However, the speed requirements in the second dimension (2nd-D) still remain one challenge for complex biological samples due to the current configuration of two column/two detector systems. Utilization of multiple 2nd-D columns can mitigate this challenge. To adapt this approach, we need a multiple channel detector. Here we develop a versatile multichannel ultraviolet (UV) light absorbance detector that is capable of simultaneously monitoring separations in 12 columns. The detector consists of a deuterium lighthouse, a flow cell assembly (a 13-channel flow cell fitted with a 13-photodiode-detection system), and a data acquisition and monitoring terminal. Through the use of a custom high optical quality furcated fiber to improve light transmission, precise machining of a flow cell to reduce background stray light through precision alignment, and sensitive electronic circuitry to reduce electronic noise through an active low pass filter, the background noise level is measured in the tens of µAU. We obtain a linear dynamic range of close to three orders of magnitude. Compared to a commercialized multichannel UV light absorbance detector like the Waters 2488 UV/Vis, our device provides an increase in channel detection while residing within the same noise region and linear range. Copyright © 2018 Elsevier B.V. All rights reserved.

Analysis of Breakthrough Profiles Based on Gamma Ray Emission Along Loaded Packed Bed Columns: Comparative Evaluation of Ionsiv IE-911 and Chabazite Zeolite for the Removal of Radiostrontium and Cesium from Groundwater

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

Bostick, D.T.; DePaoli, S.M.; Lucero, A.J.

1999-10-18

A gamma counting system has been assembled that can profile the breakthrough fronts of gamma-emitting radioisotopes longitudinally and axially along a loaded column. This profiling technique has been particularly useful in columns studies such as those performed with IONSP IE-911, a crystalline silicotitanate (CST) manufactured by UOP, in which unusually long operating times are required to observe cesium breakthrough in column effluent. The length of the mass transfer zone and extent of column saturation can be detected early in a column study by viewing the relative emission of gamma emitters along I the length of the column. In this study,more » gamma scans were used to analyze loaded CST and zeolite columns used in the treatment of process wastewater simulant and actual groundwater. Results indicate good run-to-run reproductibility in acquiring the scans. The longitudinal gamma scans for both {sup 90}Sr and {sup 137}Cs conformed with breakthrough results reported on the basis of column effluent activity. Although not obvious from data obtained by monitoring effluent activity, the gamma scans indicated that both cesium and strontium in the saturated zone of the CST column are slowly displaced by the higher levels of groundwater cations and are then resorbed further down the column. This displacement phenomenon identified by gamma scans was verified using data from a zeolite column, in which both the gamma scan and column effluent data exhibited radionuclide displacement by groundwater cations. The gamma emission intensities from the CST column runs are used to quantitate and compare the distribution coefficient and loading capacity of {sup 137}Cs on CST versus zeolite.« less

Post-Flight Back Pain Following International Space Station Missions: Evaluation of Spaceflight Risk Factors

NASA Technical Reports Server (NTRS)

Laughlin, Mitzi S.; Murray, Jocelyn D.; Wear, Mary L.; Van Baalen, Mary

2016-01-01

Back pain during spaceflight has often been attributed to the lengthening of the spinal column due to the absence of gravity during both short and long-duration missions. Upon landing and re-adaptation to gravity, the spinal column reverts back to its original length thereby causing some individuals to experience pain and muscular spasms, while others experience no ill effects. With International Space Station (ISS) missions, cases of back pain and injury are more common post-flight, but little is known about the potential risk factors.

High-throughput determination of faropenem in human plasma and urine by on-line solid-phase extraction coupled to high-performance liquid chromatography with UV detection and its application to the pharmacokinetic study.

PubMed

Xie, Rui; Wen, Jun; Wei, Hua; Fan, Guorong; Zhang, Dabing

2010-05-01

An automated system using on-line solid-phase extraction and HPLC with UV detection was developed for the determination of faropenem in human plasma and urine. Analytical process was performed isocratically with two reversed-phase columns connected by a switching valve. After simple pretreatment for plasma and urine with acetonitrile, a volume of 100microl upper layer of the plasma or urine samples was injected for on-line SPE column switching HPLC-UV analysis. The analytes were retained on the self-made trap column (Lichrospher C(18), 4.6mmx37mm, 25microm) with the loading solvent (20mM NaH(2)PO(4) adjusted pH 3.5) at flow rate of 2mlmin(-1), and most matrix materials were removed from the column to waste. After 0.5min washing, the valve was switched to another position so that the target analytes could be eluted from trap column to analytical column in the back-flush mode by the mobile phase (acetonitrile-20mM NaH(2)PO(4) adjusted pH 3.5, 16:84, v/v) at flow rate of 1.5mlmin(-1), and then separated on the analytical column (Ultimate XB-C(18), 4.6mmx50mm, 5microm).The complete cycle of the on-line SPE preconcentration purification and HPLC separation of the analytes was 5min. Calibration curves with good linearities (r=0.9994 for plasma sample and r=0.9988 for urine sample) were obtained in the range 0.02-5microgml(-1) in plasma and 0.05-10microg ml(-1) in urine for faropenem. The optimized method showed good performance in terms of specificity, linearity, detection and quantification limits, precision and accuracy. The method was successfully utilized to quantify faropenem in human plasma and urine to support the clinical pharmacokinetic studies. Copyright 2009 Elsevier B.V. All rights reserved.

Analysis of selected antibiotics in surface freshwater and seawater using direct injection in liquid chromatography electrospray ionization tandem mass spectrometry.

PubMed

Bayen, Stéphane; Yi, Xinzhu; Segovia, Elvagris; Zhou, Zhi; Kelly, Barry C

2014-04-18

Emerging contaminants such as antibiotics have received recent attention as they have been detected in natural waters and health concerns over potential antibiotic resistance. With the purpose to investigate fast and high-throughput analysis, and eventually the continuous on-line analysis of emerging contaminants, this study presents results on the analysis of seven selected antibiotics (sulfadiazine, sulfamethazine, sulfamerazine, sulfamethoxazole, chloramphenicol, lincomycin, tylosin) in surface freshwater and seawater using direct injection of a small sample volume (20μL) in liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Notably, direct injection of seawater in the LC-ESI-MS/MS was made possible on account of the post-column switch on the system, which allows diversion of salt-containing solutions flushed out of the column to the waste. Mean recoveries based on the isotope dilution method average 95±14% and 96±28% amongst the compounds for spiked freshwater and seawater, respectively. Linearity across six spiking levels was assessed and the response was linear (r(2)>0.99) for all compounds. Direct injection concentrations were compared for real samples to those obtained with the conventional SPE-based analysis and both techniques concurs on the presence/absence and levels of the compounds in real samples. These results suggest direct injection is a reliable method to detect antibiotics in both freshwater and seawater. Method detection limits for the direct injection technique (37pg/L to 226ng/L in freshwater, and from 16pg/to 26ng/L in seawater) are sufficient for a number of environmental applications, for example the fast screening of water samples for ecological risk assessments. In the present study of real samples, this new method allowed for example the positive detection of some compounds (e.g. lincomycin) down to the sub ng/L range. The direct injection method appears to be relatively cheaper and faster, requires a smaller sample size, and is more robust to equipment cross-contamination as compared to the conventional SPE-based method. Copyright © 2014 Elsevier B.V. All rights reserved.

Environmental controls on the speciation and distribution of mercury in surface sediments of a tropical estuary, India.

PubMed

Chakraborty, Parthasarathi; Babu, P V Raghunadh

2015-06-15

Distribution and speciation of mercury (Hg) in the sediments from a tropical estuary (Godavari estuary) was influenced by the changing physico-chemical parameters of the overlying water column. The sediments from the upstream and downstream of the estuary were uncontaminated but the sediments from the middle of the estuary were contaminated by Hg. The concentrations of Hg became considerably less during the monsoon and post monsoon period. Total Hg concentrations and its speciation (at the middle of the estuary) were dependent on the salinity of the overlying water column. However, salinity had little or no effect on Hg association with organic phases in the sediments at downstream. Increasing pH of the overlying water column corresponded with an increase in the total Hg content in the sediments. Total organic carbon in the sediments played an important role in controlling Hg partitioning in the system. Uncomplexed Hg binding ligands were available in the sediments. Copyright © 2015 Elsevier Ltd. All rights reserved.

Reversed-phase HPLC analysis of levetiracetam in tablets using monolithic and conventional C18 silica columns.

PubMed

Can, Nafiz O; Arli, Goksel

2010-01-01

Development and validation of an RP-HPLC method for determination of levetiracetam in pharmaceutical tablets is described. The separation and quantification of levetiracetam and caffeine (internal standard) were performed using a single analytical procedure with two different types of stationary phases, conventional Phenomenex Gemini C18 (100 x 4.6 mm, 5 microm) and Merck Chromolith Performance RP18e (100 x 4.6 mm, macropore size 2 mm, micropore size 13 nm) monolithic silica. Five-microliter aliquots of samples were injected into the system and eluted using water-acetonitrile (90 + 10, v/v) mobile phase pumped at the rate of 1 mL/min. The analyte peaks were detected at 200 nm using a diode array detector with adequate resolution. Validation studies were performed using the method recommended by the International Conference on Harmonization, the U.S. Pharmacopeia, and AOAC INTERNATIONAL, which includes accuracy, precision, range, limits, robustness, and system suitability parameters. Levetiracetam and caffeine were detected in about 7 min using the conventional column, whereas less than 5 min was required when the monolithic column was used. Calibration plots had r values close to unity in the range of 0.8-8.0 microg/mL. Assay of levetiracetam in a tablet formulation was demonstrated as an application to real samples.

HPLC-MS-MS Determination of ZCZ-011, A Novel Pharmacological Tool for Investigation of the Cannabinoid Receptor in Mouse Brain Using Clean Screen FASt™ Column Extraction.

PubMed

Poklis, Justin L; Clay, Deborah J; Ignatowska-Jankowska, Bogna M; Zanato, Chiara; Ross, Ruth A; Greig, Iain R; Abdullah, Rehab A; Mustafa, Mohammed A; Lichtman, Aron H; Poklis, Alphonse

2015-06-01

A high-performance liquid chromatography tandem mass spectrometry method was developed for the detection and quantification of 6-methyl-3-(2-nitro-1-(thiophen-2-yl)propyl)-2-phenyl-1H-indole (ZCZ-011) using 2-phenylindole as the internal standard (ISTD). ZCZ-011 was synthesized as a possible positive allosteric modulator with the CB1 cannabinoid receptor. The analytical method employs a rapid extraction technique using Clean Screen FASt™ columns with a Positive Pressure Manifold. FASt™ columns were originally developed for urine drug analysis but we have successfully adapted them to the extraction of brain tissue. Chromatographic separation was performed on a Restek Allure Biphenyl 5 µ, 100 × 3.2 mm column (Bellefonte, PA). The mobile phase consisted of 1:9 deionized water with 10 mmol ammonium acetate and 0.1% formic acid-methanol. The following transition ions (m/z) were monitored for ZCZ-011: 363 > 207 and 363 > 110 and for the ISTD: 194 > 165 and 194 > 89. The FASt™ columns lowered and stabilized the ion suppression over the linear range of the assay (40-4,000 ng/g). The method was evaluated for recovery, ion suppression, accuracy/bias, intraday and interday precision, bench-top stability, freeze-thaw and post-preparative stability. The method was successfully applied to brain tissue from C57BL/6J mice that received intraperitoneal (i.p.) injections with 40 mg/kg of ZCZ-011 or vehicle. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Simultaneous determination of aflatoxin B₁, B₂, G₁, and G₂ in corn powder, edible oil, peanut butter, and soy sauce by liquid chromatography with tandem mass spectrometry utilizing turbulent flow chromatography.

PubMed

Fan, Sufang; Li, Qiang; Zhang, Xiaoguang; Cui, Xiaobin; Zhang, Dongsheng; Zhang, Yan

2015-05-01

A novel fully automated method based on dual column switching using turbulent flow chromatography followed by liquid chromatography with tandem mass spectrometry was developed for the determination of aflatoxin B1 , B2 , G1 , and G2 in corn powder, edible oil, peanut butter, and soy sauce samples. After ultrasound-assisted extraction, samples were directly injected to the chromatographic system and the analytes were concentrated into the clean-up loading column. Through purge switching, the analytes were transferred to the analytical column for subsequent detection by mass spectrometry. Different types of TurboFlow(TM) columns, transfer flow rate, transfer time were optimized. The limits of detection and quantification of this method ranged between 0.2-2.0 and 0.5-4.0 μg/kg for aflatoxins in different matrixes, respectively. Recoveries of aflatoxins were in range of 83-108.1% for all samples, matrix effects were in range of 34.1-104.7%. The developed method has been successfully applied in the analysis of aflatoxin B1 , B2 , G1 , and G2 in real samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Observing Ocean Ecosystems with Sonar

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

Matzner, Shari; Maxwell, Adam R.; Ham, Kenneth D.

2016-12-01

We present a real-time processing system for sonar to detect and track animals, and to extract water column biomass statistics in order to facilitate continuous monitoring of an underwater environment. The Nekton Interaction Monitoring System (NIMS) is built to connect to an instrumentation network, where it consumes a real-time stream of sonar data and archives tracking and biomass data.

Identification and Quantitative Measurements of Chemical Species by Mass Spectrometry

NASA Technical Reports Server (NTRS)

Zondlo, Mark A.; Bomse, David S.

2005-01-01

The development of a miniature gas chromatograph/mass spectrometer system for the measurement of chemical species of interest to combustion is described. The completed system is a fully-contained, automated instrument consisting of a sampling inlet, a small-scale gas chromatograph, a miniature, quadrupole mass spectrometer, vacuum pumps, and software. A pair of computer-driven valves controls the gas sampling and introduction to the chromatographic column. The column has a stainless steel exterior and a silica interior, and contains an adsorbent of that is used to separate organic species. The detection system is based on a quadrupole mass spectrometer consisting of a micropole array, electrometer, and a computer interface. The vacuum system has two miniature pumps to maintain the low pressure needed for the mass spectrometer. A laptop computer uses custom software to control the entire system and collect the data. In a laboratory demonstration, the system separated calibration mixtures containing 1000 ppm of alkanes and alkenes.

75 FR 4728 - Occupational Injury and Illness Recording and Reporting Requirements

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-29

... and aggregate results available for both research and for public information. BLS only publishes... stores, and shipyards, the information from that column would have provided baseline and post... absence of the column, a person interested in MSD incidence must study every entry on the log to determine...

Open tubular lab-on-column/mass spectrometry for targeted proteomics of nanogram sample amounts.

PubMed

Hustoft, Hanne Kolsrud; Vehus, Tore; Brandtzaeg, Ole Kristian; Krauss, Stefan; Greibrokk, Tyge; Wilson, Steven Ray; Lundanes, Elsa

2014-01-01

A novel open tubular nanoproteomic platform featuring accelerated on-line protein digestion and high-resolution nano liquid chromatography mass spectrometry (LC-MS) has been developed. The platform features very narrow open tubular columns, and is hence particularly suited for limited sample amounts. For enzymatic digestion of proteins, samples are passed through a 20 µm inner diameter (ID) trypsin + endoproteinase Lys-C immobilized open tubular enzyme reactor (OTER). Resulting peptides are subsequently trapped on a monolithic pre-column and transferred on-line to a 10 µm ID porous layer open tubular (PLOT) liquid chromatography LC separation column. Wnt/ß-catenein signaling pathway (Wnt-pathway) proteins of potentially diagnostic value were digested+detected in targeted-MS/MS mode in small cell samples and tumor tissues within 120 minutes. For example, a potential biomarker Axin1 was identifiable in just 10 ng of sample (protein extract of ∼1,000 HCT15 colon cancer cells). In comprehensive mode, the current OTER-PLOT set-up could be used to identify approximately 1500 proteins in HCT15 cells using a relatively short digestion+detection cycle (240 minutes), outperforming previously reported on-line digestion/separation systems. The platform is fully automated utilizing common commercial instrumentation and parts, while the reactor and columns are simple to produce and have low carry-over. These initial results point to automated solutions for fast and very sensitive MS based proteomics, especially for samples of limited size.

Diviner Lunar Radiometer observations of the LCROSS impact.

PubMed

Hayne, Paul O; Greenhagen, Benjamin T; Foote, Marc C; Siegler, Matthew A; Vasavada, Ashwin R; Paige, David A

2010-10-22

The Lunar Reconnaissance Orbiter (LRO) Diviner instrument detected a thermal emission signature 90 seconds after the Lunar Crater Observation and Sensing Satellite (LCROSS) Centaur impact and on two subsequent orbits. The impact heated a region of 30 to 200 square meters to at least 950 kelvin, providing a sustained heat source for the sublimation of up to ~300 kilograms of water ice during the 4 minutes of LCROSS post-impact observations. Diviner visible observations constrain the mass of the sunlit ejecta column to be ~10(-6) to 10(-5) kilograms per square meter, which is consistent with LCROSS estimates used to derive the relative abundance of the ice within the regolith.

Development of an Ultrasonication-Assisted Extraction Based HPLC With a Fluorescence Method for Sensitive Determination of Aflatoxins in Highly Acidic Hibiscus sabdariffa

PubMed Central

Liu, Xiaofei; Ying, Guangyao; Sun, Chaonan; Yang, Meihua; Zhang, Lei; Zhang, Shanshan; Xing, Xiaoyan; Li, Qian; Kong, Weijun

2018-01-01

The high acidity and complex components of Hibiscus sabdariffa have provided major challenges for sensitive determination of trace aflatoxins. In this study, sample pretreatment of H. sabdariffa was systematically developed for sensitive high performance liquid chromatography-fluorescence detection (HPLC-FLD) after ultrasonication-assisted extraction, immunoaffinity column (IAC) clean-up and on-line post-column photochemical derivatization (PCD). Aflatoxins B1, B2, G1, G2 were extracted from samples by using methanol/water (70:30, v/v) with the addition of NaCl. The solutions were diluted 1:8 with 0.1 M phosphate buffer (pH 8.0) to negate the issues of high acidity and matrix interferences. The established method was validated with satisfactory linearity (R > 0.999), sensitivity (limits of detection (LODs) and limits of quantitation (LOQs) of 0.15–0.65 and 0.53–2.18 μg/kg, respectively), precision (RSD <11%), stability (RSD of 0.2–3.6%), and accuracy (recovery rates of 86.0–102.3%), which all met the stipulated analytical requirements. Analysis of 28 H. sabdariffa samples indicated that one sample incubated with Aspergillus flavus was positive with aflatoxin B1 (AFB1) at 3.11 μg/kg. The strategy developed in this study also has the potential to reliably extract and sensitively detect more mycotoxins in other complex acidic matrices, such as traditional Chinese medicines, foodstuffs, etc. PMID:29681848

Development of an Ultrasonication-Assisted Extraction Based HPLC With a Fluorescence Method for Sensitive Determination of Aflatoxins in Highly Acidic Hibiscus sabdariffa.

PubMed

Liu, Xiaofei; Ying, Guangyao; Sun, Chaonan; Yang, Meihua; Zhang, Lei; Zhang, Shanshan; Xing, Xiaoyan; Li, Qian; Kong, Weijun

2018-01-01

The high acidity and complex components of Hibiscus sabdariffa have provided major challenges for sensitive determination of trace aflatoxins. In this study, sample pretreatment of H. sabdariffa was systematically developed for sensitive high performance liquid chromatography-fluorescence detection (HPLC-FLD) after ultrasonication-assisted extraction, immunoaffinity column (IAC) clean-up and on-line post-column photochemical derivatization (PCD). Aflatoxins B 1 , B 2 , G 1 , G 2 were extracted from samples by using methanol/water (70:30, v/v ) with the addition of NaCl. The solutions were diluted 1:8 with 0.1 M phosphate buffer (pH 8.0) to negate the issues of high acidity and matrix interferences. The established method was validated with satisfactory linearity ( R > 0.999), sensitivity (limits of detection (LODs) and limits of quantitation (LOQs) of 0.15-0.65 and 0.53-2.18 μg/kg, respectively), precision (RSD <11%), stability (RSD of 0.2-3.6%), and accuracy (recovery rates of 86.0-102.3%), which all met the stipulated analytical requirements. Analysis of 28 H. sabdariffa samples indicated that one sample incubated with Aspergillus flavus was positive with aflatoxin B 1 (AFB 1 ) at 3.11 μg/kg. The strategy developed in this study also has the potential to reliably extract and sensitively detect more mycotoxins in other complex acidic matrices, such as traditional Chinese medicines, foodstuffs, etc.

Occurrence of aflatoxins in milk thistle herbal supplements.

PubMed

Tournas, V H; Sapp, C; Trucksess, M W

2012-01-01

Milk thistle (MT) dietary supplements are widely consumed due to their possible liver-health-promoting properties. As botanicals they can be contaminated with a variety of fungi and their secondary metabolites, mycotoxins. The aflatoxigenic fungus Aspergillus flavus has been previously isolated from these commodities. Currently, there is no published method for determining aflatoxins (AFs) in MT. Therefore, a liquid chromatography (LC) method validated for aflatoxin analysis in botanicals was evaluated and applied to MT. The method consisted of acetonitrile/water extraction, immunoaffinity column clean-up, LC separation, post-column photochemical reaction derivatisation and fluorescence detection. The average recoveries for AFs added to MT seeds, herb, oil-based liquid extract and alcohol-based liquid extract were 76% or higher. The mean relative standard deviation was <10%. The limit of detection (LOD) was 0.01 µg kg(-1) and the limit of quantification (LOQ) was 0.03 µg kg(-1). The method was used to conduct a small survey. A total of 83 MT samples from the US market were analysed. AFs were detected in 19% of the samples with levels ranging from 0.04 to 2.0 µg kg(-1). Additionally, an aflatoxigenic A. flavus strain from ATTC and an A. parasiticus strain isolated from MT herb powder were found to produce high amounts of aflatoxins (11,200 and 49,100 µg kg(-1), respectively) when cultured in MT seed powder. This is the first study reporting on aflatoxin contamination of MT botanical supplements and identifying methodology for AF analysis of these commodities.

Operational Test of a Sensor to Detect Aqueous Film Forming Foam (AFFF) in Ship Bilge Water

DTIC Science & Technology

2001-06-01

aqueous film forming foam ( AFFF ) in bilge water off-loaded from a ship to a shore-side wastewater treatment plant. The foam sensor uses a combination of...A sensor system was developed to detect the presence of foam producing chemicals. The sensor was primarily developed to detect the presence of...photo-optical and acoustic range measuring devices to determine the density and height of a column of foam produced by aeration of the wastewater sample

Development of On-Line High Performance Liquid Chromatography (HPLC)-Biochemical Detection Methods as Tools in the Identification of Bioactives

PubMed Central

Malherbe, Christiaan J.; de Beer, Dalene; Joubert, Elizabeth

2012-01-01

Biochemical detection (BCD) methods are commonly used to screen plant extracts for specific biological activities in batch assays. Traditionally, bioactives in the most active extracts were identified through time-consuming bio-assay guided fractionation until single active compounds could be isolated. Not only are isolation procedures often tedious, but they could also lead to artifact formation. On-line coupling of BCD assays to high performance liquid chromatography (HPLC) is gaining ground as a high resolution screening technique to overcome problems associated with pre-isolation by measuring the effects of compounds post-column directly after separation. To date, several on-line HPLC-BCD assays, applied to whole plant extracts and mixtures, have been published. In this review the focus will fall on enzyme-based, receptor-based and antioxidant assays. PMID:22489144

Perfluorinated acids as ion-pairing agents in the determination of monoamine transmitters and some prominent metabolites in rat brain by high-performance liquid chromatography with amperometric detection.

PubMed

Patthy, M; Gyenge, R

1988-09-30

The behaviour of trifluoroacetate and heptafluorobutyrate as pairing ions for the reversed-phase ion-pair separation of monoamine transmitters and related metabolites was studied. The performance of systems with the perfluorinated acids was compared with that of systems containing sodium octyl sulphonate and was found to be better in terms of peak resolution combined with total analysis time, day-to-day reproducibility and the time required for attaining initial chromatographic equilibrium. Rat brain samples were deproteinized in the acidified mobile phase, injected directly on to a high-performance liquid chromatographic column and quantitated using an amperometric detector. Sample run times were 6-8 min, at a relatively low flow-rate. The detection limits achieved are fairly uncommon with conventional bore columns. The two perfluorinated acids studied differ in the dominant mechanisms of ion-pair formation and show selectivity differences as a result.

The Trace Analysis of DEET in Water using an On-line Preconcentration Column and Liquid Chromatography with UV Photodiode Array Detection

EPA Science Inventory

A method for the detection of trace levels of N,N-diethyl-m-toluamide (DEET) in water is discussed. The method utilizes an on-line preconcentration column in series with high performance liquid chromatography (HPLC) and UV photodiode array detection. DEET, a common insect repel...

Source, impact and removal of malodour from soiled clothing.

PubMed

Denawaka, Chamila J; Fowlis, Ian A; Dean, John R

2016-03-18

Static headspace--multi-capillary column--gas chromatography--ion mobility spectrometry (SHS-MCC-GC-IMS) has been applied to the analysis of malodour compounds from soiled clothing (socks and T-shirts), pre- and post washing, at low temperature (20°C). Six volatile compounds (VCs) (i.e. butyric acid, dimethyl disulfide, dimethyl trisulfide, 2-heptanone, 2-nonanone and 2-octanone) were identified. After sensory evaluation of soiled garments they were subjected to laundering with non-perfumed washing powder. The efficiency of the laundering process was evaluated by determining the reduction of each detected volatile compound (VC) post-wash (damp) for socks and T-shirts; VC concentration reductions of between 16 and 100% were noted, irrespective of sample type. Additionally the T-shirt study considered the change in VC concentration post-wash (dry) i.e. after the drying process at ambient temperature. Overall VC concentration reductions of between 25 and 98% were noted for T-shirt samples pre-wash to post-wash (dry). Finally, a potential biochemical metabolic pathway for the formation of malodour compounds associated with bacteria in axillary sweat is proposed. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Pixelated gamma detector

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

Dolinsky, Sergei Ivanovich; Yanoff, Brian David; Guida, Renato

2016-12-27

A pixelated gamma detector includes a scintillator column assembly having scintillator crystals and optical transparent elements alternating along a longitudinal axis, a collimator assembly having longitudinal walls separated by collimator septum, the collimator septum spaced apart to form collimator channels, the scintillator column assembly positioned adjacent to the collimator assembly so that the respective ones of the scintillator crystal are positioned adjacent to respective ones of the collimator channels, the respective ones of the optical transparent element are positioned adjacent to respective ones of the collimator septum, and a first photosensor and a second photosensor, the first and the secondmore » photosensor each connected to an opposing end of the scintillator column assembly. A system and a method for inspecting and/or detecting defects in an interior of an object are also disclosed.« less

Narrow-field-of-view bathymetrical lidar: theory and field test

NASA Astrophysics Data System (ADS)

Feygels, Viktor I.; Wright, C. Wayne; Kopilevich, Yuri I.; Surkov, Alexey I.

2003-11-01

The purpose of this paper is to derive a reliable theory to predict the performance of a narrow-FOV bathymetric lidar. A fundamental discrepancy between the theoretical estimate and experimental results was the inspiration for the work presented here Meeting oceanographic mapping requirements is a critically important goal for littoral laser bathymetry. In contrast to traditional airborne lidar system which are optimized for recovering signals from the deepest possible waters , the above challenge may be met with a radical narrowing to the lidar transmit beam and receiver field of view (FOV) employed in EAARL (Experimental Advanced Airborne Research Lidar, NASA). In this paper we discuss theoretical analysis carried out on the basis of a sophisticated "multiple-forward scattering and single-backscattering model" for lidar return signals allows a quantitative estimation of the advantages of a narrow-FOV system over traditional bathymetric lidars (SHOALS-400, SHOALS-100, LADS Mk II) when used in clear shallow-water cases. Some of those advantages are: ¸ Increase in bottom definition (or reduced false-alarm probability) due to the enhanced contrast of the bottom return over the background backscatter from the water column, ¸ Enhancement in depth measurement accuracy resulting from narrower bottom return pulse width, ¸ Reduction of post-surface return effects in the lidar photo-multiplier detector due to a more rapid decay of water column backscatter, ¸ Greatly improved rejection of ambient light permitting lidar operations in all zenith sun angles and flight directions. The model computations make it possible to estimate the maximal operational depth for the system under consideration by the implementation of statistical theory of detectability. These computations depend on the prevailing seawater optical properties and lidar parameters. The theoretical predictions are compared with results obtained in the field test of the EAARL system carried out in Florida Keys in 2001.

Assay of free and glycine- and taurine-conjugated bile acids in serum by high-pressure liquid chromatography by using post-column reaction after group separation.

PubMed Central

Onishi, S; Itoh, S; Ishida, Y

1982-01-01

An accurate and sensitive method that involves the group separations of serum bile acids (i.e. free and glycine- and taurine-conjugated bile acid fractions) by ion-exchange chromatography on piperidinohydroxypropyl-Sephadex LH-20 is described. Each group was then analysed by high-pressure liquid chromatography by using the post-column reaction technique with immobilized 3 alpha-hydroxy steroid dehydrogenase. The bile acid patterns in the umbilical venous serum samples were analysed by this method. Taurochenodeoxycholate predominated in the umbilical blood. PMID:6956336

Advantages of core-shell particle columns in Sequential Injection Chromatography for determination of phenolic acids.

PubMed

Chocholouš, Petr; Vacková, Jana; Srámková, Ivana; Satínský, Dalibor; Solich, Petr

2013-01-15

Currently, for Sequential Injection Chromatography (SIC), only reversed phase C18 columns have been used for chromatographic separations. This article presents the first use of three different stationary phases: three core-shell particle-packed reversed phase columns in flow systems. The aim of this work was to extend the chromatographic capabilities of the SIC system. Despite the particle-packed columns reaching system pressures of ≤ 610 PSI, their conditions matched those of a commercially produced and optimised SIC system (SIChrom™ (FIAlab(®), USA)) with a 8-port high-pressure selection valve and medium-pressure Sapphire™ syringe pump with a 4 mL reservoir and maximum system pressure of ≤ 1000 PSI. The selectivity of each of the tested columns, Ascentis(®) Express RP-Amide, Ascentis(®) Express Phenyl-Hexyl and Ascentis(®) Express C18 (30 mm × 4.6mm, core-shell particle size 2.7 μm), was compared by their ability to separate seven phenolic acids that are secondary metabolite substances widely distributed in plants. The separations of all of the components were performed by isocratic elution using binary mobile phases composed of acetonitrile and 0.065% phosphoric acid at pH 2.4 (a specific ratio was used for each column) at a flow-rate of 0.60 mL/min. The volume of the mobile phase was 3.8 mL for each separation. The injection volume of the sample was 10 μL for each separation. The UV detection wavelengths were set to 250, 280 and 325 nm. The RP-Amide column provided the highest chromatographic resolution and allowed for complete baseline separation of protocatechuic, syringic, vanillic, ferulic, sinapinic, p-coumaric and o-coumaric acids. The Phenyl-Hexyl and C18 columns were unable to completely separate the tested mixture, syringic and vanillic acid and ferulic and sinapinic acids could not be separated from one another. The analytical parameters were a LOD of 0.3 mg L(-1), a LOQ of 1.0 mg L(-1), a calibration range of 1.0-50.0 (100.0) mg L(-1) (r>0.997) and a system precision of 10 mg L(-1) with a RSD ≤ 1.65%. The high performance of the chromatography process with the RP-Amide column under optimised conditions was highlighted and well documented (HETP values ≤ 10 μm, peak symmetry ≤ 1.33, resolution ≥ 1.87 and time for one analysis <8.0 min). The results of these experiments confirmed the benefits of extending chromatographic selectivity using core-shell particle column technology in a SIC manifold. Copyright © 2012 Elsevier B.V. All rights reserved.

Field Results for an Arctic AUV Designed for Characterizing Circulation and Ice Thickness

NASA Astrophysics Data System (ADS)

Bellingham, J. G.; Kirkwood, W. J.; Tervalon, N.; Cokelet, E.; Thomas, H.; Sibenac, M.; Gashler, D.; McEwen, R.; Henthorn, R.; Shane, F.; Osborn, D. J.; Johnson, K.; Overland, J.; Stein, P.; Bahlavouni, A.; Anderson, D.

2002-12-01

An Autonomous Underwater Vehicle designed for operation at high latitudes and under ice completed its first Arctic field tests from the USCGC Healy in fall of 2001. The ALTEX AUV has been under development since 1998, and is being created to provide: unprecedented endurance, ability to navigate at high latitudes, a depth rating of 1500 to 4500 meters depending on payload, and the capability to relay data through the ice to satellites via data buoys. The AUV's initial applications are focused on tracking the warm Atlantic Layer inflow - the primary source of seawater to the Arctic Ocean. Consequently the primary payloads are twin pumped CTD systems. Oxygen and nitrate sensors provide the ability to use NO as a tracer. An ice profiling sonar allows the AUV to estimate the ice thickness in real-time and is designed to generate high quality post-processed ice draft data comparable to that collected through the SCICEX program. The experiments in October aboard the USCGC Healy generated numerous water column and under-ice data sets. Traditional ship-based CTD operations were used to provide a comparison data set for AUV water column measurements. The post-processed ice draft results show reasonable ice profiles and have the potential, when combined with other science data collected, to shed some additional light on upper water column processes in ice-covered regions. Cruise results include: operating the AUV from the USCGC Healy in the ice pack, demonstrating inertial navigation system performance, obtaining oceanographic sections with the AUV, obtaining ice draft measurements with an AUV born sonar, and testing the data-buoy system. This work is supported by the National Science Foundation under grant NSF-OPP 9910290. The Packard Foundation and the Office of Naval Research have also provided support. The project was initiated under the National Ocean Partnership Program under contract N00014-98-1-0814.

Sequential Injection Chromatography with an Ultra-short Monolithic Column for the Low-Pressure Separation of α-Tocopherol and γ-Oryzanol in Vegetable Oils and Nutrition Supplements.

PubMed

Thaithet, Sujitra; Kradtap Hartwell, Supaporn; Lapanantnoppakhun, Somchai

2017-01-01

A low-pressure separation procedure of α-tocopherol and γ-oryzanol was developed based on a sequential injection chromatography (SIC) system coupled with an ultra-short (5 mm) C-18 monolithic column, as a lower cost and more compact alternative to the HPLC system. A green sample preparation, dilution with a small amount of hexane followed by liquid-liquid extraction with 80% ethanol, was proposed. Very good separation resolution (R s = 3.26), a satisfactory separation time (10 min) and a total run time including column equilibration (16 min) were achieved. The linear working range was found to be 0.4 - 40 μg with R 2 being more than 0.99. The detection limits of both analytes were 0.28 μg with the repeatability within 5% RSD (n = 7). Quantitative analyses of the two analytes in vegetable oil and nutrition supplement samples, using the proposed SIC method, agree well with the results from HPLC.

Monitoring/Verification using DMS: TATP Example

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

Stephan Weeks; Kevin Kyle

Field-rugged and field-programmable differential mobility spectrometry (DMS) networks provide highly selective, universal monitoring of vapors and aerosols at detectable levels from persons or areas involved with illicit chemical/biological/explosives (CBE) production. CBE sensor motes used in conjunction with automated fast gas chromatography with DMS detection (GC/DMS) verification instrumentation integrated into situational operations management systems can be readily deployed and optimized for changing application scenarios. The feasibility of developing selective DMS motes for a 'smart dust' sampling approach with guided, highly selective, fast GC/DMS verification analysis is a compelling approach to minimize or prevent the use of explosives or chemical and biologicalmore » weapons in terrorist activities. Two peroxide-based liquid explosives, triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD), are synthesized from common chemicals such as hydrogen peroxide, acetone, sulfuric acid, ammonia, and citric acid (Figure 1). Recipes can be readily found on the Internet by anyone seeking to generate sufficient quantities of these highly explosive chemicals to cause considerable collateral damage. Detection of TATP and HMTD by advanced sensing systems can provide the early warning necessary to prevent terror plots from coming to fruition. DMS is currently one of the foremost emerging technologies for the separation and detection of gas-phase chemical species. This is due to trace-level detection limits, high selectivity, and small size. DMS separates and identifies ions at ambient pressures by utilizing the non-linear dependence of an ion's mobility on the radio frequency (rf) electric field strength. GC is widely considered to be one of the leading analytical methods for the separation of chemical species in complex mixtures. Advances in the technique have led to the development of low-thermal-mass fast GC columns. These columns are capable of completing runs in less than 3 minutes. Fast GC columns are also more compact than their traditional counterparts. An earlier collaborative effort involving these authors optimized a handheld, fast GC/DMS, equipped with a non-rad ionization source, for the detection of TATP (Figure 2). The unit combines the separation capabilities of GC with the selectivity of DMS. Analytes are identified both by their elution time from the column and by the characteristic response in the DMS spectrum. Analysis times required to obtain results for these analytes are approximately 80 seconds for TATP and 160 seconds for HMTD (Figure 3). The limit of detection for both TATP and HMTD is approximately 1 ng/{micro}L. Substances that could interfere with the detection of peroxide-based explosives have been studied. Both the GC elution time and the DMS spectral peak locations were unique and do not hinder the detection of either TATP or HMTD.« less

Evaluating Precipitation Observed in Complex Terrain During GPM Field Campaigns with the SIMBA Data-Fusion Tool

NASA Astrophysics Data System (ADS)

Wingo, S. M.; Petersen, W. A.; Gatlin, P. N.; Marks, D. A.; Wolff, D. B.; Pabla, C. S.

2017-12-01

The versatile SIMBA (System for Integrating Multi-platform data to Build the Atmospheric column) precipitation data-fusion framework produces an atmospheric column data product with multi-platform observations set into a common 3-D grid, affording an efficient starting point for multi-sensor comparisons and analysis that can be applied to any region. Supported data sources include: ground-based scanning and profiling radars (S-, X-, Ku-, K-, and Ka-band), multiple types of disdrometers and rain gauges, the GPM Core Observatory's Microwave Imager (GMI, 10-183 GHz) and Dual-frequency Precipitation Radar (DPR, Ka/Ku-band), as well as thermodynamic soundings and the Multi-Radar/Multi-Sensor QPE product. SIMBA column data files provide a unique way to evaluate the complete vertical profile of precipitation. Two post-launch (GPM Core in orbit) field campaigns focused on different facets of the GPM mission: the Olympic Mountains Experiment (OLYMPEX) was geared toward winter season (November-February) precipitation in Pacific frontal systems and their transition from the coastal to mountainous terrain of northwest Washington, while the Integrated Precipitation and Hydrology Experiment (IPHEx) sampled warm season (April-June) precipitation and supported hydrologic applications in the southern Appalachians and eastern North Carolina. Both campaigns included multiple orographic precipitation enhancement episodes. SIMBA column products generated for select OLYMPEX and IPHEx events will be used to evaluate spatial variability and vertical profiles of precipitation and drop size distribution parameters derived and/or observed by space- and ground-based sensors. Results will provide a cursory view of how well the space-based measurements represent what is observed from the ground below and an indication to how the terrain in both regions impacts the characteristics of precipitation within the column and reaching the ground.

Evaluating Precipitation Observed in Complex Terrain During GPM Field Campaigns with the SIMBA Data-Fusion Tool

NASA Astrophysics Data System (ADS)

Wingo, S. M.; Petersen, W. A.; Gatlin, P. N.; Marks, D. A.; Wolff, D. B.; Pabla, C. S.

2016-12-01

The versatile SIMBA (System for Integrating Multi-platform data to Build the Atmospheric column) precipitation data-fusion framework produces an atmospheric column data product with multi-platform observations set into a common 3-D grid, affording an efficient starting point for multi-sensor comparisons and analysis that can be applied to any region. Supported data sources include: ground-based scanning and profiling radars (S-, X-, Ku-, K-, and Ka-band), multiple types of disdrometers and rain gauges, the GPM Core Observatory's Microwave Imager (GMI, 10-183 GHz) and Dual-frequency Precipitation Radar (DPR, Ka/Ku-band), as well as thermodynamic soundings and the Multi-Radar/Multi-Sensor QPE product. SIMBA column data files provide a unique way to evaluate the complete vertical profile of precipitation. Two post-launch (GPM Core in orbit) field campaigns focused on different facets of the GPM mission: the Olympic Mountains Experiment (OLYMPEX) was geared toward winter season (November-February) precipitation in Pacific frontal systems and their transition from the coastal to mountainous terrain of northwest Washington, while the Integrated Precipitation and Hydrology Experiment (IPHEx) sampled warm season (April-June) precipitation and supported hydrologic applications in the southern Appalachians and eastern North Carolina. Both campaigns included multiple orographic precipitation enhancement episodes. SIMBA column products generated for select OLYMPEX and IPHEx events will be used to evaluate spatial variability and vertical profiles of precipitation and drop size distribution parameters derived and/or observed by space- and ground-based sensors. Results will provide a cursory view of how well the space-based measurements represent what is observed from the ground below and an indication to how the terrain in both regions impacts the characteristics of precipitation within the column and reaching the ground.

Technical Note: Detection of gas bubble leakage via correlation of water column multibeam images

NASA Astrophysics Data System (ADS)

Schneider von Deimling, J.; Papenberg, C.

2012-03-01

Hydroacoustic detection of natural gas release from the seafloor has been conducted in the past by using singlebeam echosounders. In contrast, modern multibeam swath mapping systems allow much wider coverage, higher resolution, and offer 3-D spatial correlation. Up to the present, the extremely high data rate hampers water column backscatter investigations and more sophisticated visualization and processing techniques are needed. Here, we present water column backscatter data acquired with a 50 kHz prototype multibeam system over a period of 75 seconds. Display types are of swath-images as well as of a "re-sorted" singlebeam presentation. Thus, individual and/or groups of gas bubbles rising from the 24 m deep seafloor clearly emerge in the acoustic images, making it possible to estimate rise velocities. A sophisticated processing scheme is introduced to identify those rising gas bubbles in the hydroacoustic data. We apply a cross-correlation technique adapted from particle imaging velocimetry (PIV) to the acoustic backscatter images. Temporal and spatial drift patterns of the bubbles are assessed and are shown to match very well to measured and theoretical rise patterns. The application of this processing to our field data gives clear results with respect to unambiguous bubble detection and remote bubble rise velocimetry. The method can identify and exclude the main source of misinterpretations, i.e. fish-mediated echoes. Although image-based cross-correlation techniques are well known in the field of fluid mechanics for high resolution and non-inversive current flow field analysis, we present the first application of this technique as an acoustic bubble detector.

Design of five-layer gold nanoparticles self-assembled in a liquid open tubular column for ultrasensitive nano-LC-MS/MS proteomic analysis of 80 living cells.

PubMed

Shao, Xi; Zhang, Xiangmin

2017-04-01

In this work, for the first time, a liquid open tubular column modified by five-layer gold nanoparticles and linked with C 18 (GNPs@C 18 ) was designed and fabricated for nano-LC-MS/MS analysis of 80 living cells. Sixty nanometer gold nanoparticles were self-assembled layer by layer on the inner wall of a 20 μm id fused-silica capillary. C 18 was then linked on the gold nanoparticles to make the liquid open tubular column show hydrophobic character. Enough loading capacities for analysis of 80 living cells, ∼100 fmol for pk-10 and ∼30 fmol for insulin, were obtained with the 2 m × 20 μm id five-layer GNPs@C 18 open tubular column. The open tubular column was used in an online pretreatment and direct nano-LC-MS/MS analysis system to analyze 80 living HepG2 cells. In total, 650 proteins were identified in triplicate runs. The subcellular localization of the identified proteins showed that our system had no bias toward different cellular compartments. Protein copy number per cell of the identified proteins showed that the detection limit could reach 50 zmol and the abundance of the identified proteins could cover a dynamic range of 6 orders. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multidimensional gas chromatography for the characterization of permanent gases and light hydrocarbons in catalytic cracking process.

PubMed

Luong, J; Gras, R; Cortes, H J; Shellie, R A

2013-01-04

An integrated gas chromatographic system has been successfully developed and implemented for the measurement of oxygen, nitrogen, carbon monoxide, carbon dioxide and light hydrocarbons in one single analysis. These analytes are frequently encountered in critical industrial petrochemical and chemical processes like catalytic cracking of naphtha or diesel fuel to lighter components used in gasoline. The system employs a practical, effective configuration consisting of two three-port planar microfluidic devices in series with each other, having built-in fluidic gates, and a mid-point pressure source. The use of planar microfluidic devices offers intangible advantages like in-oven switching with no mechanical moving parts, an inert sample flow path, and a leak-free operation even with multiple thermal cycles. In this way, necessary features such as selectivity enhancement, column isolation, column back-flushing, and improved system cleanliness were realized. Porous layer open tubular capillary columns were employed for the separation of hydrocarbons followed by flame ionization detection. After separation has occurred, carbon monoxide and carbon dioxide were converted to methane with the use of a nickel-based methanizer for detection with flame ionization. Flow modulated thermal conductivity detection was employed to measure oxygen and nitrogen. Separation of all the target analytes was achieved in one single analysis of less than 12 min. Reproducibility of retention times for all compounds were found to be less than 0.1% (n=20). Reproducibility of area counts at two levels, namely 100 ppm(v) and 1000 ppm(v) over a period of two days were found to be less than 5.5% (n=20). Oxygen and nitrogen were found to be linear over a range from 20 ppm(v) to 10,000 ppm(v) with correlation coefficients of at least 0.998 and detection limits of less than 10 ppm(v). Hydrocarbons of interest were found to be linear over a range from 200 ppb(v) to 1000 ppm(v) with correlation coefficients of greater than 0.999 and detection limits of less than 100 ppb(v). Copyright © 2012 Elsevier B.V. All rights reserved.

Simultaneous determination of quinolones in fish by liquid chromatography coupled with fluorescence detection: comparison of sub-2 microm particles and conventional C18 columns.

PubMed

Zhang, Hong; Chen, Si; Lu, Yanbin; Dai, Zhiyuan

2010-07-01

A simple and effective multi-residue analysis method is presented for the extraction and determination of eleven quinolones (pipemidic acid, enoxacin, norfloxacin, ciprofloxacin, lomefloxacin, enrofloxacin, gatifloxacin, difloxacin, oxolinic acid, nalidixic acid and flumequine) in fish tissues. In this study, multi-residue separations on four columns packed with 5 microm or sub-2 microm particles were simultaneously developed for the purpose of comparison. Various gradients were optimized and best resolutions were achieved on each column. A short and sub-2 microm particle-sized HPLC column was chosen for its advantages in analysis time and column performance. Additionally, considering the matrix effect of the complex crude fish tissue, an effective extraction protocol was also established for sample pre-treatment procedure. Good recoveries (71-98%) were obtained from samples fortified with a mix of eleven quinolones at three levels, with satisfactory relative standard deviations and limits of detection. As a result, the sub-2 microm HPLC column and proposed analytical procedures have been evaluated and applied to the analysis of different fish tissues. Detectable residues were observed in 8 of 30 samples, at concentrations ranging from 4.74 to 23.27 microg/kg.

Pressurized capillary electrochromatographic analysis of water-soluble vitamins by combining with on-line concentration technique.

PubMed

Jia, Li; Liu, Yaling; Du, Yanyan; Xing, Da

2007-06-22

A pressurized capillary electrochromatography (pCEC) system was developed for the separation of water-soluble vitamins, in which UV absorbance was used as the detection method and a monolithic silica-ODS column as the separation column. The parameters (type and content of organic solvent in the mobile phase, type and concentration of electrolyte, pH of the electrolyte buffer, applied voltage and flow rate) affecting the separation resolution were evaluated. The combination of two on-line concentration techniques, namely, solvent gradient zone sharpening effect and field-enhanced sample stacking, was utilized to improve detection sensitivity, which proved to be beneficial to enhance the detection sensitivity by enabling the injection of large volumes of samples. Coupling electrokinetic injection with the on-line concentration techniques was much more beneficial for the concentration of positively charged vitamins. Comparing with the conventional injection mode, the enhancement in the detection sensitivities of water-soluble vitamins using the on-line concentration technique is in the range of 3 to 35-fold. The developed pCEC method was applied to evaluate water-soluble vitamins in corns.

Two-column sequential injection chromatography--new approach for fast and effective analysis and its comparison with gradient elution chromatography.

PubMed

Chocholous, Petr; Satínský, Dalibor; Sklenárová, Hana; Solich, Petr

2010-05-23

This work presents novel approach in low-pressure chromatography flow systems--two-column Sequential Injection Chromatography (2-C SIC) and its comparison with gradient elution chromatography on the same instrument. The system was equipped with two different chromatographic columns (connected to selection valve in parallel design) for isocratic separation and determination of all components in composed anti-inflammatory pharmaceutical preparation (tablets). The sample was first injected on the first column of length 30 mm where less retained analytes were separated and then the sample was injected on the second column of length 10 mm where more retained analytes were separated. The SIC system was based on a commercial SIChrom manifold (8-port high-pressure selection valve and medium-pressure syringe pump with 4 mL reservoir) (FIAlab, USA) with two commercially available monolithic columns the "first column" Chromolith Flash RP-18e (25 mm x 4.6 mm i.d. with guard column 5 mm x 4.6 mm i.d.) and the "second column" Chromolith RP-18e (10 mm x 4.6 mm i.d.) and CCD UV-vis detector USB 4000 with micro-volume 1.0 cm Z flow cell. Two mobile phases were used for analysis (one for each column). The mobile phase 1 used for elution of paracetamol, caffeine and salicylic acid (internal standard) was acetonitrile/water (10:90, v/v, the water part of pH 3.5 adjusted with acetic acid), flow rate was 0.9 mL min(-1) (volume 3.0 mL of mobile phase per analysis). The mobile phase 2 used for elution of propyphenazone was acetonitrile/water (30:70, v/v); flow rate was 1.2 mL min(-1) (volume 1.5 mL of mobile phase per analysis). Absorbance was monitored at 210 nm. Samples were prepared by dissolving of one tablet in 30% acetonitrile and 10 microL of filtered supernatant was injected on each column (2 x 10 microL). The chromatographic resolution between all compounds was >1.45 and analysis time was 5.5 min under the optimal conditions. Limits of detection were determined at 0.4 microg mL(-1) for paracetamol, at 0.5 microg mL(-1) for caffeine and at 0.7 microg mL(-1) for propyphenazone. The new two-column chromatographic set-up developed as an alternative approach to gradient elution chromatography shows evident advantages (time and solvent reduction more than one-third) as compared with single-column gradient SIC method with Chromolith Flash RP-18 (25 mm x 4.6 mm i.d. with guard column 5 mm x 4.6 mm i.d.). Copyright 2010 Elsevier B.V. All rights reserved.

Recovery of Phenanthrene-Degrading Bacteria After Simulated In Situ Persulfate Oxidation in Contaminated Soil

PubMed Central

Richardson, Stephen D.; Lebron, Benjamin L.; Miller, Cass T.; Aitken, Michael D.

2010-01-01

A continuous-flow column study was conducted to investigate the long-term effects of persulfate oxidation on the abundance and activity of the indigenous microbial community and phenanthrene-degrading bacteria in contaminated soil from a former manufactured gas plant (MGP) site. Approximately six pore volumes of a 20 g/L persulfate solution were introduced into the column, followed by simulated groundwater for 500 d. Soil samples were collected from the surface of the soil bed and along the column length immediately before and after persulfate injection and up to 500 d following injection. Exposure to persulfate led to a two- to three-log reduction in total bacterial 16S rRNA genes, severe inhibition of 14C-acetate mineralization (as a measure of general microbial activity), and a decrease in community diversity. However, relatively rapid recovery of both bacterial gene abundance and activity was observed within 30 d after persulfate exposure. Mineralization of 14C-phenanthrene was also inhibited but did not recover until 100 d post-oxidation. Known phenanthrene-degrading bacterial groups decreased to below detection limits throughout the column, with recovery times from 100 d to 500 d after persulfate injection. These findings suggest that coupling biological processes with persulfate oxidation is possible, although recovery of specific contaminant degraders may occur much later than the general microbial community recovers. Furthermore, the use of total bacterial quantity or non-specific measures of activity as a surrogate for the recovery of contaminant degraders may be inappropriate for evaluating the compatibility of chemical treatment with subsequent bioremediation. PMID:21162560

Very high pressure liquid chromatography using fully porous particles: quantitative analysis of fast gradient separations without post-run times.

PubMed

Stankovich, Joseph J; Gritti, Fabrice; Stevenson, Paul G; Beaver, Lois Ann; Guiochon, Georges

2014-01-10

Using a column packed with fully porous particles, four methods for controlling the flow rates at which gradient elution runs are conducted in very high pressure liquid chromatography (VHPLC) were tested to determine whether reproducible thermal conditions could be achieved, such that subsequent analyses would proceed at nearly the same initial temperature. In VHPLC high flow rates are achieved, producing fast analyses but requiring high inlet pressures. The combination of high flow rates and high inlet pressures generates local heat, leading to temperature changes in the column. Usually in this case a post-run time is input into the analytical method to allow the return of the column temperature to its initial state. An alternative strategy involves operating the column without a post-run equilibration period and maintaining constant temperature variations for subsequent analysis after conducting one or a few separations to bring the column to a reproducible starting temperature. A liquid chromatography instrument equipped with a pressure controller was used to perform constant pressure and constant flow rate VHPLC separations. Six replicate gradient separations of a nine component mixture consisting of acetophenone, propiophenone, butyrophenone, valerophenone, hexanophenone, heptanophenone, octanophenone, benzophenone, and acetanilide dissolved in water/acetonitrile (65:35, v/v) were performed under various experimental conditions: constant flow rate, two sets of constant pressure, and constant pressure operation with a programmed flow rate. The relative standard deviations of the response factors for all the analytes are lower than 5% across the methods. Programming the flow rate to maintain a fairly constant pressure instead of using instrument controlled constant pressure improves the reproducibility of the retention times by a factor of 5, when plotting the chromatograms in time. Copyright © 2013 Elsevier B.V. All rights reserved.

The value of automated gel column agglutination technology in the identification of true inherited D blood types in massively transfused patients.

PubMed

Summers, Thomas; Johnson, Viviana V; Stephan, John P; Johnson, Gloria J; Leonard, George

2009-08-01

Massive transfusion of D- trauma patients in the combat setting involves the use of D+ red blood cells (RBCs) or whole blood along with suboptimal pretransfusion test result documentation. This presents challenges to the transfusion service of tertiary care military hospitals who ultimately receive these casualties because initial D typing results may only reflect the transfused RBCs. After patients are stabilized, mixed-field reaction results on D typing indicate the patient's true inherited D phenotype. This case series illustrates the utility of automated gel column agglutination in detecting mixed-field reactions in these patients. The transfusion service test results, including the automated gel column agglutination D typing results, of four massively transfused D- patients transfused D+ RBCs is presented. To test the sensitivity of the automated gel column agglutination method in detecting mixed-field agglutination reactions, a comparative analysis of three automated technologies using predetermined mixtures of D+ and D- RBCs is also presented. The automated gel column agglutination method detected mixed-field agglutination in D typing in all four patients and in the three prepared control specimens. The automated microwell tube method identified one of the three prepared control specimens as indeterminate, which was subsequently manually confirmed as a mixed-field reaction. The automated solid-phase method was unable to detect any mixed fields. The automated gel column agglutination method provides a sensitive means for detecting mixed-field agglutination reactions in the determination of the true inherited D phenotype of combat casualties transfused massive amounts of D+ RBCs.

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of chlorinated pesticides in aquatic tissue by capillary-column gas chromatography with electron-capture detection

USGS Publications Warehouse

Leiker, Thomas J.; Madsen, J.E.; Deacon, J.R.; Foreman, W.T.

1995-01-01

A method for the determination of chlorinated organic compounds in aquatic tissue by dual capillary-column gas chromatography with electron-capture detection is described. Whole-body-fish or corbicula tissue is homogenized, Soxhlet extracted, lipid removed by gel permeation chromatography, and fractionated using alumina/silica adsorption chromatography. The extracts are analyzed by dissimilar capillary-column gas chromatography with electron-capture detection. The method reporting limits are 5 micrograms per kilogram (μg/kg) for chlorinated compounds, 50 μg/kg for polychlorinated biphenyls, and 200 μg/kg for toxaphene.

Vertebral bending mechanics and xenarthrous morphology in the nine-banded armadillo (Dasypus novemcinctus).

PubMed

Oliver, Jillian D; Jones, Katrina E; Hautier, Lionel; Loughry, W J; Pierce, Stephanie E

2016-10-01

The vertebral column has evolved to accommodate the broad range of locomotor pressures found across vertebrate lineages. Xenarthran (armadillos, sloths and anteaters) vertebral columns are characterized by xenarthrous articulations, novel intervertebral articulations located in the posterior trunk that are hypothesized to stiffen the vertebral column to facilitate digging. To determine the degree to which xenarthrous articulations impact vertebral movement, we passively measured compliance and range of motion during ventroflexion, dorsiflexion and lateral bending across the thoracolumbar region of the nine-banded armadillo, Dasypus novemcinctus Patterns of bending were compared with changes in vertebral morphology along the column to determine which morphological features best predict intervertebral joint mechanics. We found that compliance was lower in post-diaphragmatic, xenarthrous vertebrae relative to pre-xenarthrous vertebrae in both sagittal and lateral planes of bending. However, we also found that range of motion was higher in this region. These changes in mechanics are correlated with the transition from pre-xenarthrous to xenarthrous vertebrae, as well as with the transition from thoracic to lumbar vertebrae. Our results thus substantiate the hypothesis that xenarthrous articulations stiffen the vertebral column. Additionally, our data suggest that xenarthrous articulations, and their associated enlarged metapophyses, also act to increase the range of motion of the post-diaphragmatic region. We propose that xenarthrous articulations perform the dual role of stiffening the vertebral column and increasing mobility, resulting in passively stable vertebrae that are capable of substantial bending under appropriate loads. © 2016. Published by The Company of Biologists Ltd.

An on-line SPE-HPLC method for effective sample preconcentration and determination of fenoxycarb and cis, trans-permethrin in surface waters.

PubMed

Šatínský, Dalibor; Naibrtová, Linda; Fernández-Ramos, Carolina; Solich, Petr

2015-09-01

A new on-line SPE-HPLC method using fused-core columns for on-line solid phase extraction and large volume sample injection for increasing the sensitivity of detection was developed for the determination of insecticides fenoxycarb and cis-, trans-permethrin in surface waters. The separation was carried out on fused-core column Phenyl-Hexyl (100×4.6 mm), particle size 2.7 µm with mobile phase acetonitrile:water in gradient mode at flow rate 1.0 mL min(-1), column temperature 45°C. Large volume sample injection (1500 µL) to the extraction dimension using short precolumn Ascentis Express RP C-18 (5×4.6 mm); fused-core particle size 2.7 µm allowed effective sample preconcentration and efficient ballast sample matrix removal. The washing mobile phase consisting of a mixture of acetonitrile:water; 30:70, (v/v) was pumped at flow rate of 0.5 mL min(-1) through the extraction precolumn to the waste. Time of the valve switch for transferring the preconcentrated sample zone from the extraction to the separation column was set at 3rd min. Elution of preconcentrated insecticides from the extraction precolumn and separation on the analytical column was performed in gradient mode. Linear gradient elution started from 40% of acetonitrile at time of valve switch from SPE column (3rd min) to 95% of acetonitrile at 7th min. Synthetic dye sudan I was chosen as an internal standard. UV detection at wavelength 225 nm was used and the method reached the limits of detection (LOD) at ng mL(-1) levels for both insecticides. The method showing on-line sample pretreatment and preconcentration with highly sensitive determination of insecticides was applied for monitoring of fenoxycarb and both permethrin isomers in different surface water samples in Czech Republic. The time of whole analysis including on-line extraction, interferences removal, chromatography separation and system equilibration was less than 8 min. Copyright © 2015 Elsevier B.V. All rights reserved.

AIRIS Wide Area Detection System

DTIC Science & Technology

2003-07-01

herbicola, the chemical stimulant SF6, as well as the interferents kaolin clay dust, Dugway road dust, and diesel soot. In this paper we will report on...the SF6 column density of approximately 200 ppmv-m. In future work we hope to correlate this measurement with a Gaussian plume dispersion model of

An on-line coupling of nanofibrous extraction with column-switching high performance liquid chromatography - A case study on the determination of bisphenol A in environmental water samples.

PubMed

Háková, Martina; Chocholoušová Havlíková, Lucie; Chvojka, Jiří; Solich, Petr; Šatínský, Dalibor

2018-02-01

Polyamide 6 nanofiber polymers were used as modern sorbents for on-line solid phase extraction (SPE) coupled with liquid chromatography. The on-line SPE system was tested for the determination of bisphenol A in river water samples. Polyamide nanofibers were prepared using needleless electrospinning, inserted into a mini-column cartridge (5 × 4.6mm) and coupled with HPLC. The effect of column packing and the amount of polyamide 6 on extraction efficiency was tested and the packing process was optimized. The proposed method was performed using a 50-µL sample injection followed by an on-line nanofibrous extraction procedure. The influence of the washing mobile phase on the retention of bisphenol A during the extraction procedure was evaluated. Ascentis ® Express C18 (10cm × 4.6mm) core-shell column was used as an analytical column. Fluorescence detection wavelengths (λ ex = 225nm and λ em = 320nm) were used for identification and quantification of Bisphenol A in river waters. The linearity was tested in the range from 2 to 500µgL -1 (using nine calibration points). The limits of detection and quantification were 0.6 and 2µgL -1 , respectively. The developed method was successfully used for the determination of bisphenol A in various samples of river waters in the Czech Republic (The Ohře, Labe, Nisa, Úpa, and Opava Rivers). Copyright © 2017 Elsevier B.V. All rights reserved.

Constraining the H2 column density distribution at z ˜ 3 from composite DLA spectra

NASA Astrophysics Data System (ADS)

Balashev, S. A.; Noterdaeme, P.

2018-07-01

We present the detection of the average H2 absorption signal in the overall population of neutral gas absorption systems at z˜ 3 using composite absorption spectra built from the Sloan Digital Sky Survey-III damped Lyman α catalogue. We present a new technique to directly measure the H2 column density distribution function f_H_2(N) from the average H2 absorption signal. Assuming a power-law column density distribution, we obtain a slope β = -1.29 ± 0.06(stat) ± 0.10 (sys) and an incidence rate of strong H2 absorptions [with N(H2) ≳ 1018 cm-2] to be 4.0 ± 0.5(stat) ± 1.0 (sys) per cent in H I absorption systems with N(H I) ≥1020 cm-2. Assuming the same inflexion point where f_H_2(N) steepens as at z = 0, we estimate that the cosmological density of H2 in the column density range log N(H_2) (cm^{-2})= 18{-}22 is {˜ } 15 per cent of the total. We find one order of magnitude higher H2 incident rate in a sub-sample of extremely strong damped Lyman α absorption systems (DLAs) [log N(H I) (cm^{-2}) ≥ 21.7], which, together with the derived shape of f_H_2(N), suggests that the typical H I-H2 transition column density in DLAs is log N(H)(cm-2) ≳ 22.3 in agreement with theoretical expectations for the average (low) metallicity of DLAs at high-z.

Comparison of a novel passive sampler to standard water-column sampling for organic contaminants associated with wastewater effluents entering a New Jersey stream

USGS Publications Warehouse

Alvarez, D.A.; Stackelberg, P.E.; Petty, J.D.; Huckins, J.N.; Furlong, E.T.; Zaugg, S.D.; Meyer, M.T.

2005-01-01

Four water samples collected using standard depth and width water-column sampling methodology were compared to an innovative passive, in situ, sampler (the polar organic chemical integrative sampler or POCIS) for the detection of 96 organic wastewater-related contaminants (OWCs) in a stream that receives agricultural, municipal, and industrial wastewaters. Thirty-two OWCs were identified in POCIS extracts whereas 9-24 were identified in individual water-column samples demonstrating the utility of POCIS for identifying contaminants whose occurrence are transient or whose concentrations are below routine analytical detection limits. Overall, 10 OWCs were identified exclusively in the POCIS extracts and only six solely identified in the water-column samples, however, repetitive water samples taken using the standard method during the POCIS deployment period required multiple trips to the sampling site and an increased number of samples to store, process, and analyze. Due to the greater number of OWCs detected in the POCIS extracts as compared to individual water-column samples, the ease of performing a single deployment as compared to collecting and processing multiple water samples, the greater mass of chemical residues sequestered, and the ability to detect chemicals which dissipate quickly, the passive sampling technique offers an efficient and effective alternative for detecting OWCs in our waterways for wastewater contaminants.

HPLC determination of cefprozil in tablets using monolithic and C18 silica columns.

PubMed

Can, Nafiz O

2011-08-01

Cefprozil (CPZ) is a second-generation semi-synthetic cephalosporin antibiotic that commonly exists as the mixture of Z and E diastereoisomers, at the ratio of approximately 9:1. A novel reversed-phase HPLC method for the determination of CPZ in tablets was described. The separation of CPZ diastereoisomers and caffeine (internal standard) was carried out by applying the same analytical and instrumental conditions on two stationary phases, which have different surface chemistries. The columns used in the study were monolithic silica Merck Chromolith Performance RP-18e and conventional C18 silica Phenomenex Synergi Hydro RP columns. In total, 10 μL aliquots of samples were injected into the system and eluted using water-acetonitrile (90:10, v/v) solution, which was pumped through the column at a flow rate of 1.0 mL/min. The analyte peaks were detected at 200 nm using diode array detector with high specificity. CPZ diastereoisomers and caffeine were measured within 13 min using the C18 column, whereas <5 min was required for the monolithic one. Validation studies were performed according to official recommendations. Value of a monolithic column for the assay of diastereoisomers in pharmaceutical tablets was evaluated for the first time and found as a powerful alternative to highly efficient C18 columns. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pretreatment method for immunoassay of polychlorinated biphenyls in transformer oil using multilayer capillary column and microfluidic liquid-liquid partitioning.

PubMed

Aota, Arata; Date, Yasumoto; Terakado, Shingo; Ohmura, Naoya

2013-01-01

Polychlorinated biphenyls (PCBs) are persistent organic pollutants that are present in the insulating oil inside a large number of transformers. To aid in eliminating PCB-contaminated transformers, PCBs in oil need to be measured using a rapid and cost-effective analytical method. We previously reported a pretreatment method for the immunoassay of PCBs in oil using a large-scale multilayer column and a microchip with multiple microrecesses, which permitted concentrated solvent extraction. In this paper, we report on a more rapid and facile pretreatment method, without an evaporation process, by improving the column and the microchip. In a miniaturized column, the decomposition and separation of oil were completed in 2 min. PCBs can be eluted from the capillary column at concentrations seven-times higher than those from the previous column. The total volume of the microrecesses was increased by improving the microrecess structure, the enabling extraction of four-times the amount of PCBs achieved with the previous system. By interfacing the capillary column with the improved microchip, PCBs in the eluate from the column were extracted into dimethyl sulfoxide in microrecesses with high enrichment and without the need for evaporation. Pretreatment was completed within 20 min. The pretreated oil was analyzed using a flow-based kinetic exclusion immunoassay. The limit of detection of PCBs in oil was 0.15 mg kg(-1), which satisfies the criterion set in Japan of 0.5 mg kg(-1).

Remote calorimetric detection of urea via flow injection analysis

PubMed Central

Gaddes, David E.; Demirel, Melik C.; Reeves, W. Brian; Tadigadapa, Srinivas

2017-01-01

The design and development of a calorimetric biosensing system enabling relatively high throughput sample analysis are reported. The calorimetric biosensor system consists of a thin (~20 μm) micromachined Y-cut quartz crystal resonator (QCR) as a temperature sensor placed in close proximity to a fluidic chamber packed with an immobilized enzyme. Layer by layer enzyme immobilization of urease is demonstrated and its activity as a function of the number of layers, pH, and time has been evaluated. This configuration enables a sensing system where a transducer element is physically separated from the analyte solution of interest and is thereby free from fouling effects typically associated with biochemical reactions occuring on the sensor surface. The performance of this biosensing system is demonstrated by detection of 1–200 mM urea in phosphate buffer via a flow injection analysis (FIA) technique. Miniaturized fluidic systems were used to provide continuous flow through a reaction column. Under this configuration the biosensor has an ultimate resolution of less than 1 mM urea and showed a linear response between 0–50 mM. This work demonstrates a sensing modality in which the sensor itself is not fouled or contaminated by the solution of interest and the enzyme immobilized Kapton® fluidic reaction column can be used as a disposable cartridge. Such a system enables reuse and reliability for long term sampling measurements. Based on this concept a biosensing system is envisioned which can perform rapid measurements to detect biomarkers such as glucose, creatinine, cholesterol, urea and lactate in urine and blood continuously over extended periods of time. PMID:26479269

Remote calorimetric detection of urea via flow injection analysis.

PubMed

Gaddes, David E; Demirel, Melik C; Reeves, W Brian; Tadigadapa, Srinivas

2015-12-07

The design and development of a calorimetric biosensing system enabling relatively high throughput sample analysis are reported. The calorimetric biosensor system consists of a thin (∼20 μm) micromachined Y-cut quartz crystal resonator (QCR) as a temperature sensor placed in close proximity to a fluidic chamber packed with an immobilized enzyme. Layer by layer enzyme immobilization of urease is demonstrated and its activity as a function of the number of layers, pH, and time has been evaluated. This configuration enables a sensing system where a transducer element is physically separated from the analyte solution of interest and is thereby free from fouling effects typically associated with biochemical reactions occuring on the sensor surface. The performance of this biosensing system is demonstrated by detection of 1-200 mM urea in phosphate buffer via a flow injection analysis (FIA) technique. Miniaturized fluidic systems were used to provide continuous flow through a reaction column. Under this configuration the biosensor has an ultimate resolution of less than 1 mM urea and showed a linear response between 0-50 mM. This work demonstrates a sensing modality in which the sensor itself is not fouled or contaminated by the solution of interest and the enzyme immobilized Kapton® fluidic reaction column can be used as a disposable cartridge. Such a system enables reuse and reliability for long term sampling measurements. Based on this concept a biosensing system is envisioned which can perform rapid measurements to detect biomarkers such as glucose, creatinine, cholesterol, urea and lactate in urine and blood continuously over extended periods of time.

Separation and Detection of Toxic Gases with a Silicon Micromachined Gas Chromatography System

NASA Technical Reports Server (NTRS)

Kolesar, Edward S.; Reston, Rocky R.

1995-01-01

A miniature gas chromatography (GC) system was designed and fabricated using silicon micromachining and integrated circuit (IC) processing techniques. The silicon micromachined gas chromatography system (SMGCS) is composed of a miniature sample injector that incorporates a 10 microliter sample loop; a 0.9 meter long, rectangular shaped (300 micrometer width and 10 micrometer height) capillary column coated with a 0.2 micrometer thick copper phthalocyanine (CuPc) stationary phase; and a dual detector scheme based upon a CuPc-coated chemiresistor and a commercially available 125 micrometer diameter thermal conductivity detector (TCD) bead. Silicon micromachining was employed to fabricate the interface between the sample injector and the GC column, the column itself, and the dual detector cavity. A novel IC thin-film processing technique was developed to sublime the CuPc stationary phase coating on the column walls that were micromachined in the host silicon wafer substrate and Pyrex (r) cover plate, which were then electrostatically bonded together. The SMGCS can separate binary gas mixtures composed of parts-per-million (ppm) concentrations of ammonia (NH3) and nitrogen dioxide (NO2) when isothermally operated (55-80 degrees C). With a helium carrier gas and nitrogen diluent, a 10 microliter sample volume containing ammonia and nitrogen dioxide injected at 40 psi ((2.8 x 10(exp 5)Pa)) can be separated in less than 30 minutes.

RP-HPLC ANALYSIS OF ACIDIC AND BASIC DRUGS IN SYSTEMS WITH DIETHYLAMINE AS ELUENTS ADDITIVE.

PubMed

Petruczynik, Anna; Wroblewski, Karol; Strozek, Szymon; Waksmundzka-Hajnos, Monika

2016-11-01

The chromatographic behavior of some basic and acidic drugs was studied on Cl 8, Phenyl-Hexyl and Polar RP columns with methanol or acetonitrile as organic modifiers of aqueous mobile phases containing addition of diethylamine. Diethylamine plays a double function of silanol blocker reagent in analysis of basic drugs and ion-pair reagent in analysis of acidic drugs. Most symmetrical peaks and highest system efficiency were obtained on Phenyl-Hexyl and Polar RP columns in tested mobile phase systems compared to results obtained on C18 column. A new rapid, simple, specific and accurate reverse phase liquid chromatographic method was developed for the simultaneous determination of atorvastatin - antihyperlipidemic drug and amlodipine - calcium channel blocker in one pharmaceutical formulation. Atorvastatin is an acidic compounds while amlodipine is a basic substance. The chromatographic separation was carried out on Phenyl-Hexyl column by gradient elution mode with acetonitrile as organic modifier, acetate buffer at pH 3.5 and Q.025 M/L diethylamine. The proposed method was validated for specificity, precision, accuracy, linearity, and robustness. The linearity range of atorvastatin and amlodipine for 5 - 100 μg/mL was obtained with limits of-detection (LOD) 3.2750 gg/mL and 3.2102 μg/mL, respectively. The proposed method made use of DAD as a tool for peak identity and purity confirmation.

The hippocampal system as the cortical resource manager: a model connecting psychology, anatomy and physiology.

PubMed

Coward, L Andrew

2010-01-01

A model is described in which the hippocampal system functions as resource manager for the neocortex. This model is developed from an architectural concept for the brain as a whole within which the receptive fields of neocortical columns can gradually expand but with some limited exceptions tend not to contract. The definition process for receptive fields is constrained so that they overlap as little as possible, and change as little as possible, but at least a minimum number of columns detect their fields within every sensory input state. Below this minimum, the receptive fields of some columns are expanded slightly until the minimum level is reached. The columns in which this expansion occurs are selected by a competitive process in the hippocampal system that identifies those in which only a relatively small expansion is required, and sends signals to those columns that trigger the expansion. These expansions in receptive fields are the information record that forms the declarative memory of the input state. Episodic memory activates a set of columns in which receptive fields expanded simultaneously at some point in the past, and the hippocampal system is therefore the appropriate source for information guiding access to such memories. Semantic memory associates columns that are often active (with or without expansions in receptive fields) simultaneously. Initially, the hippocampus can guide access to such memories on the basis of initial information recording, but to avoid corruption of the information needed for ongoing resource management, access control shifts to other parts of the neocortex. The roles of the mammillary bodies, amygdala and anterior thalamic nucleus can be understood as modulating information recording in accordance with various behavioral priorities. During sleep, provisional physical connectivity is created that supports receptive field expansions in the subsequent wake period, but previously created memories are not affected. This model matches a wide range of neuropsychological observation better than alternative hippocampal models. The information mechanisms required by the model are consistent with known brain anatomy and neuron physiology.

The applicability of animal health surveillance systems for post-market monitoring of potential adverse effects of genetically modified (GM) feed.

PubMed

Vince, L; Kleter, G A; Kostov, K; Pfeiffer, D U; Guitian, J

2018-04-20

A facultative post market monitoring of potential health impacts of genetically modified (GM) feedstuffs on livestock consuming these feeds after pre-market risk assessment is under ongoing consideration. Within the IPAFEED database, scientific studies on health effects beyond performance in livestock and the results of a systematic search for evidence of outcome effects due to GM feed are consolidated. These outcomes were reviewed and checked for consistency in order to identify plausible syndromes suitable for conducting surveillance. The 24 selected studies showed no consistent changes in any health parameter. There were no repeated studies in any species by GM crop type and animal species. As such, there is insufficient evidence to inform the design of surveillance systems for detecting known adverse effects. Animal health surveillance systems have been proposed for the post market monitoring of potential adverse effects in animals. Such systems were evaluated for their applicability to the detection of hypothetical adverse effects and their strengths and weaknesses to detect syndromes of concern are presented. For known adverse effects, applied controlled post-market studies may yield conclusive and high-quality evidence. For detecting unknown adverse effects, the use of existing surveillance systems may still be of interest. A simulation tool developed within the project can be adapted and applied to existing surveillance systems to explore their applicability to the detection of potential adverse effects of GM feed. Copyright © 2018. Published by Elsevier Ltd.

An automated HPLC method for the fractionation of polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans in fish tissue on a porous graphitic carbon column

USGS Publications Warehouse

Echols, Kathy R.; Gale, Robert W.; Tillitt, Donald E.; Schwartz, Ted R.; O'Laughlin, Jerome

1997-01-01

The Ah (aryl-hydrocarbon) hydroxylase-receptor active polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were fractionated by an automated high-performance liquid chromatography (HPLC) system using the Hypercarb™ porous graphitic carbon (PGC) column. This commercially available column was used to fractionate the di-, mono-, and non-ortho PCBs into three fractions for gas chromatography (GC)/electron capture detection analysis, and a fourth fraction containing the PCDDs/PCDFs for GC/mass spectrometry analysis. The recoveries of the PCBs ranged from 68 to 96%, and recoveries of the PCDDs/PCDFs ranged from 74 to 123%. The PGC column has the advantage of faster separations (110 min versus 446 min) and less solvent use (275 ml versus 1,100 ml) compared with automated fractionation of these compounds on activated carbon (PX-21), while still affording good separation of the classes. The PGC column may have an advantage over the pyrenyl-based HPLC method because it has a greater loading capacity (400 μg total PCBs versus 250 μg). Overall, the PGC is a standard column that provides reproducible fractionation of PCDD/PCDFs and PCBs for analytical measurement in environmental samples.

Measurement of trace nitrate concentrations in seawater by ion chromatography with valve switching

NASA Astrophysics Data System (ADS)

Du, Juan; Fa, Yun; Zheng, Yue; Li, Xuebing; Du, Fanglin; Yang, Haiyan

2014-05-01

An ion chromatographic method with a valve switching facility was developed to determine trace nitrate concentrations in seawater using two pumps, two different suppressors, and two columns. A carbohydrate membrane desalter was used to reduce the high concentrations of sodium salts in samples. In this method, trace nitrate was eluted from the concentrator column to the analytical columns, while the matrix fl owed to waste. Neither chemical pre-treatment nor sample dilution was required. In the optimized separation conditions, the method showed good linearity ( R >0.99) in the 0.05 and 50 mg/L concentration range, and satisfactory repeatability (RSD<5%, n =6). The limit of detection for nitrate was 0.02 mg/L. Results showed that the valve switching system was suitable and practical for the determination of trace nitrate in seawater.

Imaging, Mapping and Monitoring Environmental Radionuclide Transport Using Compton-Geometry Gamma Camera

NASA Astrophysics Data System (ADS)

Bridge, J. W.; Dormand, J.; Cooper, J.; Judson, D.; Boston, A. J.; Bankhead, M.; Onda, Y.

2014-12-01

The legacy to-date of the nuclear disaster at Fukushima Dai-ichi, Japan, has emphasised the fundamental importance of high quality radiation measurements in soils and plant systems. Current-generation radiometers based on coded-aperture collimation are limited in their ability to locate sources of radiation in three dimensions, and require a relatively long measurement time due to the poor efficiency of the collimation system. The quality of data they can provide to support biogeochemical process models in such systems is therefore often compromised. In this work we report proof-of-concept experiments demonstrating the potential of an alternative approach in the measurement of environmentally-important radionuclides (in particular 137Cs) in quartz sand and soils from the Fukushima exclusion zone. Compton-geometry imaging radiometers harness the scattering of incident radiation between two detectors to yield significant improvements in detection efficiency, energy resolution and spatial location of radioactive sources in a 180° field of view. To our knowledge we are reporting its first application to environmentally-relevant systems at low activity, dispersed sources, with significant background radiation and, crucially, movement over time. We are using a simple laboratory column setup to conduct one-dimensional transport experiments for 139Ce and 137Cs in quartz sand and in homogenized repacked Fukushima soils. Polypropylene columns 15 cm length with internal diameter 1.6 cm were filled with sand or soil and saturated slowly with tracer-free aqueous solutions. Radionuclides were introduced as 2mL pulses (step-up step-down) at the column inlet. Data were collected continuously throughout the transport experiment and then binned into sequential time intervals to resolve the total activity in the column and its progressive movement through the sand/soil. The objective of this proof-of-concept work is to establish detection limits, optimise image reconstruction algorithms, and develop a novel approach to time-lapse quantification of radionuclide dynamics in the soil-plant system. The aim is to underpin the development of a new generation of Compton radiometers equipped to provide high resolution, dynamic measurements of radionuclides in terrestrial biogeochemical environments.

CO-dark molecular gas at high redshift: very large H2 content and high pressure in a low-metallicity damped Lyman alpha system

NASA Astrophysics Data System (ADS)

Balashev, S. A.; Noterdaeme, P.; Rahmani, H.; Klimenko, V. V.; Ledoux, C.; Petitjean, P.; Srianand, R.; Ivanchik, A. V.; Varshalovich, D. A.

2017-09-01

We present a detailed analysis of an H2-rich, extremely strong intervening damped Ly α absorption system (DLA) at zabs = 2.786 towards the quasar J 0843+0221, observed with the Ultraviolet and Visual Echelle Spectrograph on the Very Large Telescope. The total column density of molecular (resp. atomic) hydrogen is log N(H2) = 21.21 ± 0.02 (resp. log N(H I) = 21.82 ± 0.11), making it to be the first case in quasar absorption line studies with H2 column density as high as what is seen in 13CO-selected clouds in the Milky Way. We find that this system has one of the lowest metallicity detected among H2-bearing DLAs, with [Zn/H] = -1.52^{+0.08}_{-0.10}. This can be the reason for the marked differences compared to systems with similar H2 column densities in the local Universe: (I) the kinetic temperature, T ˜ 120 K, derived from the J = 0, 1 H2 rotational levels is at least twice higher than expected; (II) there is little dust extinction with AV < 0.1; (III) no CO molecules are detected, putting a constraint on the XCO factor XCO > 2 × 1023 cm-2/(km s-1 K), in the very low metallicity gas. Low CO and high H2 contents indicate that this system represents 'CO-dark/faint' gas. We investigate the physical conditions in the H2-bearing gas using the fine-structure levels of C I, C II, Si II and the rotational levels of HD and H2. We find the number density to be about n ˜ 260-380 cm-3, implying a high thermal pressure of 3-5 × 104 cm-3 K. We further identify a trend of increasing pressure with increasing total hydrogen column density. This independently supports the suggestion that extremely strong DLAs (with log N(H) ˜22) probe high-z galaxies at low impact parameters.

Cyclic performance of concrete-filled steel batten built-up columns

NASA Astrophysics Data System (ADS)

Razzaghi, M. S.; Khalkhaliha, M.; Aziminejad, A.

2016-03-01

Steel built-up batten columns are common types of columns in Iran and some other parts of the world. They are economic and have acceptable performance due to gravity loads. Although several researches have been conducted on the behavior of the batten columns under axial loads, there are few available articles about their seismic performance. Experience of the past earthquakes, particularly the 2003 Bam earthquake in Iran, revealed that these structural members are seismically vulnerable. Thus, investigation on seismic performance of steel batten columns due to seismic loads and providing a method for retrofitting them are important task in seismic-prone areas. This study aims to investigate the behavior of concrete-filled batten columns due to combined axial and lateral loads. To this end, nonlinear static analyses were performed using ANSYS software. Herein, the behaviors of the steel batten columns with and without concrete core were compared. The results of this study showed that concrete-filled steel batten columns, particularly those filled with high-strength concrete, may cause significant increases in energy absorption and capacity of the columns. Furthermore, concrete core may improve post-buckling behavior of steel batten columns.

Evaluation of long-term prestress losses in post-tensioned box-girder bridges.

DOT National Transportation Integrated Search

2011-03-01

Most of the recent highway bridges built in California have post-tensioned, cast-in-place, concrete box-girder superstructures rigidly connected to bridge columns. However, methods provided in the current (2007 and 2010) AASHTO LRFD Bridge Design Spe...

A novel approach to signal normalisation in atmospheric pressure ionisation mass spectrometry.

PubMed

Vogeser, Michael; Kirchhoff, Fabian; Geyer, Roland

2012-07-01

The aim of our study was to test an alternative principle of signal normalisation in LC-MS/MS. During analyses, post column infusion of the target analyte is done via a T-piece, generating an "area under the analyte peak" (AUP). The ratio of peak area to AUP is assessed as assay response. Acceptable analytical performance of this principle was found for an exemplary analyte. Post-column infusion may allow normalisation of ion suppression not requiring any additional standard compound. This approach can be useful in situations where no appropriate compound is available for classical internal standardisation. Copyright © 2012 Elsevier B.V. All rights reserved.

Spin and Flux Evolution of the New Magnetar Swift J1822.3-1606

NASA Astrophysics Data System (ADS)

Ng, Stephen C.-Y.; Kaspi, Victoria; Cumming, Andrew; Livingstone, Margaret; Scholz, Paul; Archibald, Robert

2012-07-01

On 2011 July 14, a transient X-ray source, Swift J1822.3-1606, was first detected by Swift BAT via its burst activities. It was subsequently identified as a new magnetar upon the detection of a pulse period of 8.4s. Using follow-up RXTE, Swift, and Chandra observations, we determined a spin-down rate of ~1.6e-13, giving a dipole magnetic field of ~3.8e13G, second lowest among known magnetars. The post-outburst flux evolution can be model by a double exponential decay with timescales of 11 and 58 days. We found an absorption column density similar to that of the open cluster M17 at 16' away, arguing a comparable distance of ~1.6kpc for Swift J1823.3-1606. If confirmed, this will be the nearest magnetar observed. We also discuss the possibility that the magnetar progenitor was born in M17.

The new magnetar Swift J1822.3-1606

NASA Astrophysics Data System (ADS)

Scholz, P.; Ng, C.-Y.; Livingstone, M. A.; Kaspi, V. M.; Cumming, A.; Archibald, R.

2013-03-01

On 2011 July 14, a transient X-ray source, Swift J1822.3-1606, was detected by Swift BAT via its burst activities. It was subsequently identified as a new magnetar upon the detection of a pulse period of 8.4 s. Using follow-up RXTE, Swift, and Chandra observations, we have determined a spin-down rate of Ṗ ~ 3 × 10-13, implying a dipole magnetic field of ~ 5 × 1013 G, second lowest among known magnetars, although our timing solution is contaminated by timing noise. The post-outburst flux evolution is well modelled by surface cooling resulting from heat injection in the outer crust, although we cannot rule out other models. We measure an absorption column density similar to that of the open cluster M17 at 10' away, arguing for a comparable distance of ~1.6 kpc. If confirmed, this could be the nearest known magnetar.

Rapid determination of collagen in meat-based foods by microwave hydrolysis of proteins and HPAEC-PAD analysis of 4-hydroxyproline.

PubMed

Messia, M C; Di Falco, T; Panfili, G; Marconi, E

2008-10-01

A rapid microwave procedure for protein hydrolysis coupled with High Performance Anion Exchange Chromatography and Pulsed Amperometric Detection (HPAEC-PAD) was developed to quantify the amino acid 4-hydroxyproline in meat and meat-based products. This innovative approach was successfully applied to determine collagen content (4-hydroxyproline×8) as the index quality of meat material employed in the preparation of typical meat sausages ("Mortadella di Bologna PGI" and "Salamini italiani alla cacciatora PDO") and fresh filled pastas. Microwave hydrolysis showed a precision and accuracy similar to traditional hydrolysis (RSD% from 0.0 to 6.4; relative error 1.4-10.0%) with a reduction in the hydrolysis time from 24h to 20min. HPAEC-PAD allowed detection of 4-hydroxyproline without pre or post-column derivatization and the use of non-toxic eluents.

An active acoustic tripwire for simultaneous detection and localization of multiple underwater intruders.

PubMed

Folegot, Thomas; Martinelli, Giovanna; Guerrini, Piero; Stevenson, J Mark

2008-11-01

An algorithm allowing simultaneous detection and localization of multiple submerged targets crossing an acoustic tripwire based on forward scattering is described and then evaluated based upon data collected at sea. This paper quantifies the agreement between the theoretical performance and the results obtained from processing data gathered at sea for crossings at several depths and ranges. Targets crossing the acoustic field produce shadows on each side of the barrier, for specific sensors and for specific acoustic paths. In post-processing, a model is invoked to associate expected paths with the observed shadows. This process allows triangulation of the target's position inside the acoustic field. Precise localization is achieved by taking advantage of the multipath propagation structure of the received signal, together with the diversity of the source and receiver locations. Environmental robustness is demonstrated using simulations and can be explained by the use of an array of sources spatially distributed through the water column.

Very high pressure liquid chromatography using core-shell particles: quantitative analysis of fast gradient separations without post-run times.

PubMed

Stankovich, Joseph J; Gritti, Fabrice; Stevenson, Paul G; Beaver, Lois A; Guiochon, Georges

2014-01-17

Five methods for controlling the mobile phase flow rate for gradient elution analyses using very high pressure liquid chromatography (VHPLC) were tested to determine thermal stability of the column during rapid gradient separations. To obtain rapid separations, instruments are operated at high flow rates and high inlet pressure leading to uneven thermal effects across columns and additional time needed to restore thermal equilibrium between successive analyses. The purpose of this study is to investigate means to minimize thermal instability and obtain reliable results by measuring the reproducibility of the results of six replicate gradient separations of a nine component RPLC standard mixture under various experimental conditions with no post-run times. Gradient separations under different conditions were performed: constant flow rates, two sets of constant pressure operation, programmed flow constant pressure operation, and conditions which theoretically should yield a constant net heat loss at the column's wall. The results show that using constant flow rates, programmed flow constant pressures, and constant heat loss at the column's wall all provide reproducible separations. However, performing separations using a high constant pressure with programmed flow reduces the analysis time by 16% compared to constant flow rate methods. For the constant flow rate, programmed flow constant pressure, and constant wall heat experiments no equilibration time (post-run time) was required to obtain highly reproducible data. Copyright © 2013 Elsevier B.V. All rights reserved.

HPLC-DAD-FLD Method for Simultaneous Determination of Mycotoxins in Wheat Bran.

PubMed

Irakli, Maria N; Skendi, Adriana; Papageorgiou, Maria D

2017-08-01

Aflatoxins, deoxynivalenol, ochratoxin A and zearalenone are the most important mycotoxins that everyone on its own, in groups or simultaneously contaminate cereals. The external layers of cereal grains (bran) apart from health promoting ingredients are also the most contaminated part with reference to mycotoxin's presence. Therefore, consumption of a high fiber wheat-based diet represent an increased risk to consumer's health. The objective of this study was to develop a simple and reliable high performance liquid chromatography method for the simultaneous determination of these mycotoxins in wheat bran (WB). A double extraction was applied with phosphate buffered saline/methanol and for the clean-up a multi-immunoaffinity column was utilized. The detection was carried out with diode-array and fluorescence detectors linked with a post-column photochemical reactor. After optimization of the chromatographic conditions, all mycotoxins were eluted within ~26 min. Limits of detection for each mycotoxin (0.12-12.58 µg/kg) were below the maximum levels provisioned by European Union regulations. Good linearity was observed for the analytes (r2 ≥ 0.9980). The recovery of analyzed mycotoxins ranged from 70.2 to 105.8%, with a relative standard deviation <12%. The method was successfully applied to quantify mycotoxins in 34 WB samples obtained after pearling of grains that were collected from different regions of Greece. © Crown copyright 2017.

In-depth analyses of native N-linked glycans facilitated by high-performance anion exchange chromatography-pulsed amperometric detection coupled to mass spectrometry.

PubMed

Szabo, Zoltan; Thayer, James R; Agroskin, Yury; Lin, Shanhua; Liu, Yan; Srinivasan, Kannan; Saba, Julian; Viner, Rosa; Huhmer, Andreas; Rohrer, Jeff; Reusch, Dietmar; Harfouche, Rania; Khan, Shaheer H; Pohl, Christopher

2017-05-01

Characterization of glycans present on glycoproteins has become of increasing importance due to their biological implications, such as protein folding, immunogenicity, cell-cell adhesion, clearance, receptor interactions, etc. In this study, the resolving power of high-performance anion exchange chromatography with pulsed amperometric detection (HPAE-PAD) was applied to glycan separations and coupled to mass spectrometry to characterize native glycans released from different glycoproteins. A new, rapid workflow generates glycans from 200 μg of glycoprotein supporting reliable and reproducible annotation by mass spectrometry (MS). With the relatively high flow rate of HPAE-PAD, post-column splitting diverted 60% of the flow to a novel desalter, then to the mass spectrometer. The delay between PAD and MS detectors is consistent, and salt removal after the column supports MS. HPAE resolves sialylated (charged) glycans and their linkage and positional isomers very well; separations of neutral glycans are sufficient for highly reproducible glycoprofiling. Data-dependent MS 2 in negative mode provides highly informative, mostly C- and Z-type glycosidic and cross-ring fragments, making software-assisted and manual annotation reliable. Fractionation of glycans followed by exoglycosidase digestion confirms MS-based annotations. Combining the isomer resolution of HPAE with MS 2 permitted thorough N-glycan annotation and led to characterization of 17 new structures from glycoproteins with challenging glycan profiles.

Degradation of Triphenyltin by a Fluorescent Pseudomonad

PubMed Central

Inoue, Hiroyuki; Takimura, Osamu; Fuse, Hiroyuki; Murakami, Katsuji; Kamimura, Kazuo; Yamaoka, Yukiho

2000-01-01

Triphenyltin (TPT)-degrading bacteria were screened by a simple technique using a post-column high-performance liquid chromatography using 3,3′,4′,7-tetrahydroxyflavone as a post-column reagent for determination of TPT and its metabolite, diphenyltin (DPT). An isolated strain, strain CNR15, was identified as Pseudomonas chlororaphis on the basis of its morphological and biochemical features. The incubation of strain CNR15 in a medium containing glycerol, succinate, and 130 μM TPT resulted in the rapid degradation of TPT and the accumulation of approximately 40 μM DPT as the only metabolite after 48 h. The culture supernatants of strain CNR15, grown with or without TPT, exhibited a TPT degradation activity, whereas the resting cells were not capable of degrading TPT. TPT was stoichiometrically degraded to DPT by the solid-phase extract of the culture supernatant, and benzene was detected as another degradation product. We found that the TPT degradation was catalyzed by low-molecular-mass substances (approximately 1,000 Da) in the extract, termed the TPT-degrading factor. The other fluorescent pseudomonads, P. chlororaphis ATCC 9446, Pseudomonas fluorescens ATCC 13525, and Pseudomonas aeruginosa ATCC 15692, also showed TPT degradation activity similar to strain CNR15 in the solid-phase extracts of their culture supernatants. These results suggest that the extracellular low-molecular-mass substance that is universally produced by the fluorescent pseudomonad could function as a potent catalyst to cometabolite TPT in the environment. PMID:10919812

Application of an online post-column derivatization HPLC-DPPH assay to detect compounds responsible for antioxidant activity in Sonchus oleraceus L. leaf extracts.

PubMed

Ou, Zong-Quan; Schmierer, David M; Rades, Thomas; Larsen, Lesley; McDowell, Arlene

2013-02-01

To use an online assay to identify key antioxidants in Sonchus oleraceus leaf extracts and to investigate the effect of leaf position and extraction conditions on antioxidant concentration and activity. Separation of phytochemicals and simultaneous assessment of antioxidant activity were performed online using HPLC and post-column reaction with a free-radical reagent (2, 2-diphenylpicrylhydrazyl, DPPH). Active compounds were identified using nuclear magnetic resonance spectroscopy and mass spectrometry. We applied the online HPLC-DPPH radical assay to evaluate antioxidants in leaves from different positions on the plant and to assess the effect of pre-treatment of leaves with liquid N(2) before grinding, extraction time, extraction temperature and method of concentrating extracts. Key antioxidants identified in S. oleraceus leaf extracts were caftaric acid, chlorogenic acid and chicoric acid. Middle leaves contained the highest total amount of the three key antioxidant compounds, consisting mainly of chicoric acid. Pre-treatment with liquid N(2), increasing the extraction temperature and time and freeze-drying the extract did not enhance the yield of the key antioxidants. The online HPLC-DPPH radical assay was validated as a useful screening tool for investigating individual antioxidants in leaf extracts. Optimized extraction conditions were middle leaves pre-treated with liquid N(2), extraction at 25°C for 0.5 h and solvent removal by rotary evaporation. © 2012 The Authors. JPP © 2012. Royal Pharmaceutical Society.

Analytical applications of enhanced drug luminescence.

PubMed

Baeyens, W R; Ling, B L

1989-01-01

Luminescence emission from drugs is strongly dependent on their physicochemical environment. Several biomedically and environmentally important compounds and pharmaceuticals exhibit sufficient intrinsic luminescence properties to allow their determination by high-performance liquid chromatography (HPLC) with fluorimetric, chemiluminescence or room temperature phosphorimetric detection. In the case of weakly fluorescing compounds it is possible to use the dependence of the emitted radiation on the molecular environment at the moment of measurement. The composition of the eluent, i.e. solvents, added salts and buffers, pH and ionic strength, oxygen content and temperature, are of the highest importance for the luminescence detection of drugs in solution (e.g. in liquid chromatography) or adsorbed onto solid surfaces (e.g. in thin-layer chromatography). Post-column or post-plate acid-base manipulation and the use of specific reagents may remarkably enhance the observed luminescence of several molecules. The term "enhancement" of luminescence comprises various sample treatments leading to an increase of the emitted radiation. These treatments include the addition of non-fluorescent compounds to, or the creation of organized media (surfactants, cyclodextrins, heavy atoms) in, the sample to be measured. They may also involve changes in molecular environment, pH, the application of excessive drying conditions, the removal of oxygen, the protection of adsorbed compounds against non-radiative decay mechanisms by means of specific spraying or dipping conditions, amongst others. The use of organized media in luminescence spectroscopy is growing. Many of the recent studies have involved micelles for enhancing the fluorescence, room temperature phosphorescence and chemiluminescence of several chemicals. Cyclodextrins are increasingly used for various analytical applications. Liquid paraffin, triethanolamine, dodecane, Triton X-100 and Fomblin Y-Vac are commonly used fluorescence enhancers in chromatographic assays. Examples of these systems in drug analysis are presented.

Thermal barrier and support for nuclear reactor fuel core

DOEpatents

Betts, Jr., William S.; Pickering, J. Larry; Black, William E.

1987-01-01

A thermal barrier/core support for the fuel core of a nuclear reactor having a metallic cylinder secured to the reactor vessel liner and surrounded by fibrous insulation material. A top cap is secured to the upper end of the metallic cylinder that locates and orients a cover block and post seat. Under normal operating conditions, the metallic cylinder supports the entire load exerted by its associated fuel core post. Disposed within the metallic cylinder is a column of ceramic material, the height of which is less than that of the metallic cylinder, and thus is not normally load bearing. In the event of a temperature excursion beyond the design limits of the metallic cylinder and resulting in deformation of the cylinder, the ceramic column will abut the top cap to support the fuel core post.

[Implementation of a post-discharge surgical site infection system in herniorrhaphy and mastectomy procedures].

PubMed

San Juan Sanz, Isabel; Díaz-Agero-Pérez, Cristina; Robustillo-Rodela, Ana; Pita López, María José; Oliva Iñiguez, Lourdes; Monge-Jodrá, Vicente

2014-10-01

Monitoring surgical site infection (SSI) performed during hospitalization can underestimate its rates due to the shortening in hospital stay. The aim of this study was to determine the actual rates of SSI using a post-discharge monitoring system. All patients who underwent herniorraphy or mastectomy in the Hospital Universitario Ramón y Cajal from 1 January 2011 to 31 December 2011 were included. SSI data were collected prospectively according to the continuous quality improvement indicators (Indicadores Clinicos de Mejora Continua de la Calidad [INCLIMECC]) monitoring system. Post-discharge follow-up was conducted by telephone survey. A total of 409patients were included in the study, of whom 299 underwent a herniorraphy procedure, and 110 underwent a mastectomy procedure. For herniorrhaphy, the SSI rate increased from 6.02% to 7.6% (the post-discharge survey detected 21.7% of SSI). For mastectomy, the SSI rate increased from 1.8% to 3.6% (the post-discharge survey detected 50% of SSI). Post-discharge monitoring showed an increased detection of SSI incidence. Post-discharge monitoring is useful to analyze the real trend of SSI, and evaluate improvement actions. Post-discharge follow-up methods need to standardised. Copyright © 2013 Elsevier España, S.L.U. y Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Performance of the fixed-bed of granular activated carbon for the removal of pesticides from water supply.

PubMed

Alves, Alcione Aparecida de Almeida; Ruiz, Giselle Louise de Oliveira; Nonato, Thyara Campos Martins; Müller, Laura Cecilia; Sens, Maurício Luiz

2018-02-26

The application of a fixed bed adsorption column of granular activated carbon (FBAC-GAC), in the removal of carbaryl, methomyl and carbofuran at a concentration of 25 μg L -1 for each carbamate, from the public water supply was investigated. For the determination of the presence of pesticides in the water supply, the analytical technique of high-performance liquid chromatography with post-column derivatization was used. Under conditions of constant diffusivity, the FBAC-GAC was saturated after 196 h of operation on a pilot scale. The exhaust rate of the granular activated carbon (GAC) in the FBAC-GAC until the point of saturation was 0.02 kg GAC m -3 of treated water. By comparing a rapid small-scale column test and FBAC-GAC, it was confirmed that the predominant intraparticle diffusivity in the adsorption column was constant diffusivity. Based on the results obtained on a pilot scale, it was possible to estimate the values to be applied in the FBAC-GAC (full scale) to remove the pesticides, which are particle size with an average diameter of 1.5 mm GAC; relationship between the internal diameter of the column and the average diameter of GAC ≥50 in order to avoid preferential flow near the adsorption column wall; surface application rate 240 m 3  m -2  d -1 and an empty bed contact time of 3 min. BV: bed volume; CD: constant diffusivity; EBCT: empty bed contact time; FBAC-GAC: fixed bed adsorption column of granular activated carbon; GAC: granular activated carbon; MPV: maximum permitted values; NOM: natural organic matter; PD: proportional diffusivity; pH PCZ : pH of the zero charge point; SAR: surface application rate; RSSCT: rapid small-scale column test; WTCS: water treated conventional system.

Smart-aggregate-based damage detection of fiber-reinforced-polymer-strengthened columns under reversed cyclic loading

NASA Astrophysics Data System (ADS)

Howser, Rachel; Moslehy, Yashar; Gu, Haichang; Dhonde, Hemant; Mo, Y. L.; Ayoub, Ashraf; Song, Gangbing

2011-07-01

Structural health monitoring is an important aspect of the maintenance of large civil infrastructures, especially for bridge columns in areas of high seismic activity. In this project, recently developed innovative piezoceramic-based sensors were utilized to perform the health monitoring of a shear-critical reinforced concrete (RC) bridge column subjected to reversed cyclic loading. After the column failed, it was wrapped with fiber reinforced polymer (FRP) sheets, commonly used to retrofit seismically damaged structures. The FRP-strengthened column was retested under the same reversed cyclic loading pattern. Innovative piezoceramic-based sensors, called 'smart aggregates', were utilized as transducers for health monitoring purposes. On the basis of the smart aggregates developed, an active-sensing approach and an impact-hammer-based approach were used to evaluate the health status of the RC column during the loading procedure. Wave transmission energy is attenuated by the existence of cracks during the loading procedure, and this attenuation phenomenon alters the curve of the transfer function between the actuator and sensor. To detect the damage occurrence and evaluate the damage severity, transfer function curves were compared with those obtained during the period of healthy status. A transfer-function-based damage index matrix was developed to demonstrate the damage severity at different locations. Experimental results verified the effectiveness of the smart aggregates in health monitoring of the FRP-strengthened column as well as the unstrengthened column. The experimental results show that the proposed smart-aggregate-based approach can successfully detect damage occurrence and evaluate its severity.

Determination of ambroxol hydrochloride, methylparaben and benzoic acid in pharmaceutical preparations based on sequential injection technique coupled with monolithic column.

PubMed

Satínský, Dalibor; Huclová, Jitka; Ferreira, Raquel L C; Montenegro, Maria Conceição B S M; Solich, Petr

2006-02-13

The porous monolithic columns show high performance at relatively low pressure. The coupling of short monoliths with sequential injection technique (SIA) results in a new approach to implementation of separation step to non-separation low-pressure method. In this contribution, a new separation method for simultaneous determination of ambroxol, methylparaben and benzoic acid was developed based on a novel reversed-phase sequential injection chromatography (SIC) technique with UV detection. A Chromolith SpeedROD RP-18e, 50-4.6 mm column with 10 mm precolumn and a FIAlab 3000 system with a six-port selection valve and 5 ml syringe were used for sequential injection chromatographic separations in our study. The mobile phase used was acetonitrile-tetrahydrofuran-0.05M acetic acid (10:10:90, v/v/v), pH 3.75 adjusted with triethylamine, flow rate 0.48 mlmin(-1), UV-detection was at 245 nm. The analysis time was <11 min. A new SIC method was validated and compared with HPLC. The method was found to be useful for the routine analysis of the active compounds ambroxol and preservatives (methylparaben or benzoic acid) in various pharmaceutical syrups and drops.

Reduction of Solvent Effect in Reverse Phase Gradient Elution LC-ICP-MS

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

Sullivan, Patrick Allen

2005-12-17

Quantification in liquid chromatography (LC) is becoming very important as more researchers are using LC, not as an analytical tool itself, but as a sample introduction system for other analytical instruments. The ability of LC instrumentation to quickly separate a wide variety of compounds makes it ideal for analysis of complex mixtures. For elemental speciation, LC is joined with inductively coupled plasma mass spectrometry (ICP-MS) to separate and detect metal-containing, organic compounds in complex mixtures, such as biological samples. Often, the solvent gradients required to perform complex separations will cause matrix effects within the plasma. This limits the sensitivity ofmore » the ICP-MS and the quantification methods available for use in such analyses. Traditionally, isotope dilution has been the method of choice for LC-ICP-MS quantification. The use of naturally abundant isotopes of a single element in quantification corrects for most of the effects that LC solvent gradients produce within the plasma. However, not all elements of interest in speciation studies have multiple naturally occurring isotopes; and polyatomic interferences for a given isotope can develop within the plasma, depending on the solvent matrix. This is the case for reverse phase LC separations, where increasing amounts of organic solvent are required. For such separations, an alternative to isotope dilution for quantification would be is needed. To this end, a new method was developed using the Apex-Q desolvation system (ESI, Omaha, NE) to couple LC instrumentation with an ICP-MS device. The desolvation power of the system allowed greater concentrations of methanol to be introduced to the plasma prior to destabilization than with direct methanol injection into the plasma. Studies were performed, using simulated and actual linear methanol gradients, to find analyte-internal standard (AIS) pairs whose ratio remains consistent (deviations {+-} 10%) over methanol concentration ranges of 5%-35% (simulated) and 8%-32% (actual). Quadrupole (low resolution) and sector field (high resolution) ICP-MS instrumentation were utilized in these studies. Once an AIS pair is determined, quantification studies can be performed. First, an analysis is performed by adding both elements of the AIS pair post-column while performing the gradient elution without sample injection. A comparison of the ratio of the measured intensities to the atomic ratio of the two standards is used to determine a correction factor that can be used to account for the matrix effects caused by the mobile phase. Then, organic and/or biological molecules containing one of the two elements in the AIS pair are injected into the LC column. A gradient method is used to vary the methanol-water mixture in the mobile phase and to separate out the compounds in a given sample. A standard solution of the second ion in the AIS pair is added continuously post-column. By comparing the ratio of the measured intensities to the atomic ratio of the eluting compound and internal standard, the concentration of the injected compound can be determined.« less

Water column and bed-sediment core samples collected from Brownlee Reservoir near Oxbow, Oregon, 2012

USGS Publications Warehouse

Fosness, Ryan L.; Naymik, Jesse; Hopkins, Candice B.; DeWild, John F.

2013-01-01

The U.S. Geological Survey, in cooperation with Idaho Power Company, collected water-column and bed-sediment core samples from eight sites in Brownlee Reservoir near Oxbow, Oregon, during May 5–7, 2012. Water-column and bed-sediment core samples were collected at each of the eight sites and analyzed for total mercury and methylmercury. Additional bed-sediment core samples, collected from three of the eight sites, were analyzed for pesticides and other organic compounds, trace metals, and physical characteristics, such as particle size. Total mercury and methylmercury were detected in each of the water column and bed-sediment core samples. Only 17 of the 417 unique pesticide and organic compounds were detected in bed-sediment core samples. Concentrations of most organic wastewater compounds detected in bed sediment were less than the reporting level. Trace metals detected were greater than the reporting level in all the bed-sediment core samples submitted for analysis. The particle size distribution of bed-sediment core samples was predominantly clay mixed with silt.

Methane fluxes and their controlling processes in the Baltic Sea

NASA Astrophysics Data System (ADS)

Rehder, G. J.; Fossing, H.; Lapham, L.; Endler, R.; Spiess, V.; Bruchert, V.; Nguyen, T.; Gülzow, W.; Schneider von Deimling, J.; Conley, D. J.; Jorgensen, B.

2010-12-01

The Baltic Sea is an ideal natural laboratory to study the methane cycle in the framework of diagenetic processes. With its brackish character and a gradient from nearly marine to almost limnic conditions, a strong permanent haline stratification leading to large vertical redox gradients in the water column, and a sedimentation history which resulted in the deposition of organic-rich young post-glacial sediments over older glacial and post-glacial strata with very low organic content, the Baltic allows to study the role of a variety of key parameters for early diagenetic processes including the methane cycle. Within the BONUS + Project “Baltic Gas”, a 3.5 week scientific expedition of RV Maria S. Merian in August 2010 was dedicated to study the methane cycle in the various basins of the Baltic Sea, with strong emphasis on the metabolic reactions of early diagenesis and the occurrence of shallow gas deposits. Various subbottom profiling systems were used to map the thickness and structure of organic-rich deposits and build the base for a detailed coring program for biogeochemical analysis, including methane, sulfur compounds, iron, and other compounds. Methane gradients in connection with the information of the areal extend of organic-rich deposits are used to estimate the diffusive flux from the sediments into the water column and the rate of methane oxidation, with changing importance of sulfate as oxidant along the salinity gradient. On selected key stations, rate measurements of methanogenic and methanotrophic reactions were executed. The methane distribution in the water column was comprehensively assessed, revealing amongst other findings a drastic increase in bottom water methane concentration between the post bloom summer situation and the situation in the winter of 2009, in connection to the occurrence of a benthic nepheloid layer. Air-sea flux measurements were executed along the ship’s track comprising all major basins of the Baltic. The talk gives an interdisciplinary overview of the first results of this research campaign.

[Simultaneous analysis of trehalose, glucose and maltose in biotransformation samples by high performance anion exchange chromatography with pulsed ampere detection].

PubMed

Xu, Ying; Zang, Ying; Jiang, Ting; Zheng, Zhaojuan; Quyang, Jia

2014-12-01

An analytical method for the determination of trehalose, maltose, and glucose in biotransformation samples was developed by using high performance anion exchange chromatography coupled with pulsed ampere detection (HPAEC-PAD). The analysis was performed on a CarboPac™ 10 column (250 mm x 2 mm) with the gradient elution of NaOH-NaAc as the mobile phase. The column temperature was set at 30 °C, the flow rate was 0. 30 mL/min. The results showed that trehalose, maltose, and glucose in biotransformation system were completely separated and determined in 15 min. The linear ranges and the working curves were determined by using standard samples. The correlation coefficients of three kinds of carbohydrates were over 0. 9998 . The detection limits (LODs) were 0. 010 - 0. 100 mg/L. Under the optimized separation conditions, the recoveries of saccharides in the transformation system at three different spiked levels ranged from 89. 4% to 103. 2%. In biotransformation system, 50 IU trehalose synthase were added into 200 g/L maltose for reaction of 8 h at 37 °C, pH 8. 0. Under the above conditions, the concentration of trehalose in biotransformation sample was 101. 084 g/L, and the conversion rate of trehalose reached 50. 5%. The method can be applied to determine the composition in the transformation system with the advantages of simplicity and convenience.

Chlorophyll-a thin layers in the Magellan fjord system: The role of the water column stratification

NASA Astrophysics Data System (ADS)

Ríos, Francisco; Kilian, Rolf; Mutschke, Erika

2016-08-01

Fjord systems represent hotspots of primary productivity and organic carbon burial. However, the factors which control the primary production in mid-latitude fjords are poorly understood. In this context, results from the first fine-scale measurements of bio-oceanographic features in the water column of fjords associated with the Strait of Magellan are presented. A submersible fluorescence probe (FP) was used to measure the Chlorophyll-a (Chl-a) concentration in situ, along with conductivity, temperature, hydrostatic pressure (depth) and dissolved oxygen (CTD-O2) of the water column. The Austral spring results of 14 FP-CTD-O2 profiles were used to define the vertical and horizontal patches of the fluorescent pigment distribution and their spatial relations with respect to the observed hydrographic features. Three zones with distinct water structures were defined. In all zones, the 'brown' spectral group (diatoms and dinoflagellates) predominated accounting for >80 wt% of the phytoplankton community. Thin layers with high Chl-a concentration were detected in 50% of the profiles. These layers harbored a substantial amount (30-65 wt%) of the phytoplankton biomass. Stratification was positively correlated to the occurrence of Chl-a thin layers. In stable and highly stratified water columns the integrated Chl-a concentration was higher and frequently located within thin layers whereas well mixed water columns displayed lower values and more homogeneous vertical distribution of Chl-a. These results indicate that mixing/stability processes are important factors accounting to the vertical distribution of Chl-a in Magellan fjords.

Gas Chromatograph Method Optimization Trade Study for RESOLVE: 20-meter Column v. 8-meter Column

NASA Technical Reports Server (NTRS)

Huz, Kateryna

2014-01-01

RESOLVE is the payload on a Class D mission, Resource Prospector, which will prospect for water and other volatile resources at a lunar pole. The RESOLVE payload's primary scientific purpose includes determining the presence of water on the moon in the lunar regolith. In order to detect the water, a gas chromatograph (GC) will be used in conjunction with a mass spectrometer (MS). The goal of the experiment was to compare two GC column lengths and recommend which would be best for RESOLVE's purposes. Throughout the experiment, an Inficon Fusion GC and an Inficon Micro GC 3000 were used. The Fusion had a 20m long column with 0.25mm internal diameter (Id). The Micro GC 3000 had an 8m long column with a 0.32mm Id. By varying the column temperature and column pressure while holding all other parameters constant, the ideal conditions for testing with each column length in their individual instrument configurations were determined. The criteria used for determining the optimal method parameters included (in no particular order) (1) quickest run time, (2) peak sharpness, and (3) peak separation. After testing numerous combinations of temperature and pressure, the parameters for each column length that resulted in the most optimal data given my three criteria were selected. The ideal temperature and pressure for the 20m column were 95 C and 50psig. At this temperature and pressure, the peaks were separated and the retention times were shorter compared to other combinations. The Inficon Micro GC 3000 operated better at lower temperature mainly due to the shorter 8m column. The optimal column temperature and pressure were 70 C and 30psig. The Inficon Micro GC 3000 8m column had worse separation than the Inficon Fusion 20m column, but was able to separate water within a shorter run time. Therefore, the most significant tradeoff between the two column lengths was peak separation of the sample versus run time. After performing several tests, it was concluded that better detection via good peak separation with a longer run time is a better asset than moderate peak separation with a shorter run time. Even given that RESOLVE is highly interested in water and that mission timeline is of significant importance given the short seven-to-ten-day mission timeline, worse detection with an 8m column may lead to overlooking other substances existing on the moon that could advance planetary science. Thus, I recommend the 20m column. However, if mission timeline and water separation are deemed the highest priority, the 8m column should be selected due to its ability to separate water within a shorter run time than the 20m column.

A programmable palm-size gas analyzer for use in micro-autonomous systems

NASA Astrophysics Data System (ADS)

Gordenker, Robert J. M.; Wise, Kensall D.

2012-06-01

Gas analysis systems having small size, low power, and high selectivity are badly needed for defense (detection of explosives and chemical warfare agents), homeland security, health care, and environmental applications. This paper presents a palm-size gas chromatography system having analysis times of 5-50sec, detection limits less than 1ppb, and an average power dissipation less than one watt. It uses no consumables. The three-chip fluidic system consists of a preconcentrator, a 25cm-3m separation column, and a chemi-resistive detector and is supported by a microcomputer and circuitry for programmable temperature control. The entire system, including the mini-pump and battery, occupies less than 200cc and is configured for use on autonomous robotic vehicles.

Optimization of microfabricated nanoliter-scale solid-phase extraction device for detection of gel-separated proteins in low abundance by matrix-assisted laser desorption/ionization mass spectrometry.

PubMed

Chen, Wenzhang; Shen, Jing; Yin, Xuefeng; Yu, Yingnian

2007-01-01

A nano-scale solid-phase extraction (SPE) device was developed for the detection of gel-separated proteins in low abundance by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) with a simplified microfabrication technology. By using SU-8 photoresist instead of epoxy glue to connect the microchannel and transfer capillary, polymeric contaminant signals in MS analysis were significantly reduced. Micro SPE columns with different capacities and geometric characteristics were investigated in order to increase the detection sensitivity and decrease spot size for MALDI-TOF-MS analysis. It is shown that enhancements in sensitivities for the detection of proteins in low abundance were correlated with the reduction in column capacity and increase in column aspect ratio. Fifty nanoliters of matrix solution were sufficient to elute the sample completely from the optimized micro SPE column with 3.5 nL capacity. The mass spectrum of a 5 fmol in-gel tryptic digest of bovine serum albumin (BSA), processed by the micro SPE column, demonstrated that 29 peptides matched the protein giving a sequence coverage of 51%, which was better than that obtained from analysis of 25 fmol of the same sample prepared by the dried-droplet method. With the micro SPE column treatment of 2 microL of digestion supernatant of a gel spot of the IQGAP1 protein, 15 peptides were detected from the mass spectrum with the highest individual score of 111, while, with a ZipTip procedure, only nine peaks were detected with the highest individual score of 71. Analytical results demonstrated that this approach greatly improved the sequence coverage and identification specificity for the tested protein. It can serve as a very useful tool in proteomics studies, especially for low abundance proteins. Copyright (c) 2006 John Wiley & Sons, Ltd.

Mobile autonomous robotic apparatus for radiologic characterization

DOEpatents

Dudar, Aed M.; Ward, Clyde R.; Jones, Joel D.; Mallet, William R.; Harpring, Larry J.; Collins, Montenius X.; Anderson, Erin K.

1999-01-01

A mobile robotic system that conducts radiological surveys to map alpha, beta, and gamma radiation on surfaces in relatively level open areas or areas containing obstacles such as stored containers or hallways, equipment, walls and support columns. The invention incorporates improved radiation monitoring methods using multiple scintillation detectors, the use of laser scanners for maneuvering in open areas, ultrasound pulse generators and receptors for collision avoidance in limited space areas or hallways, methods to trigger visible alarms when radiation is detected, and methods to transmit location data for real-time reporting and mapping of radiation locations on computer monitors at a host station. A multitude of high performance scintillation detectors detect radiation while the on-board system controls the direction and speed of the robot due to pre-programmed paths. The operators may revise the preselected movements of the robotic system by ethernet communications to remonitor areas of radiation or to avoid walls, columns, equipment, or containers. The robotic system is capable of floor survey speeds of from 1/2-inch per second up to about 30 inches per second, while the on-board processor collects, stores, and transmits information for real-time mapping of radiation intensity and the locations of the radiation for real-time display on computer monitors at a central command console.

Mobile autonomous robotic apparatus for radiologic characterization

DOEpatents

Dudar, A.M.; Ward, C.R.; Jones, J.D.; Mallet, W.R.; Harpring, L.J.; Collins, M.X.; Anderson, E.K.

1999-08-10

A mobile robotic system is described that conducts radiological surveys to map alpha, beta, and gamma radiation on surfaces in relatively level open areas or areas containing obstacles such as stored containers or hallways, equipment, walls and support columns. The invention incorporates improved radiation monitoring methods using multiple scintillation detectors, the use of laser scanners for maneuvering in open areas, ultrasound pulse generators and receptors for collision avoidance in limited space areas or hallways, methods to trigger visible alarms when radiation is detected, and methods to transmit location data for real-time reporting and mapping of radiation locations on computer monitors at a host station. A multitude of high performance scintillation detectors detect radiation while the on-board system controls the direction and speed of the robot due to pre-programmed paths. The operators may revise the preselected movements of the robotic system by ethernet communications to remonitor areas of radiation or to avoid walls, columns, equipment, or containers. The robotic system is capable of floor survey speeds of from 1/2-inch per second up to about 30 inches per second, while the on-board processor collects, stores, and transmits information for real-time mapping of radiation intensity and the locations of the radiation for real-time display on computer monitors at a central command console. 4 figs.

Particle detector spatial resolution

DOEpatents

Perez-Mendez, V.

1992-12-15

Method and apparatus for producing separated columns of scintillation layer material, for use in detection of X-rays and high energy charged particles with improved spatial resolution is disclosed. A pattern of ridges or projections is formed on one surface of a substrate layer or in a thin polyimide layer, and the scintillation layer is grown at controlled temperature and growth rate on the ridge-containing material. The scintillation material preferentially forms cylinders or columns, separated by gaps conforming to the pattern of ridges, and these columns direct most of the light produced in the scintillation layer along individual columns for subsequent detection in a photodiode layer. The gaps may be filled with a light-absorbing material to further enhance the spatial resolution of the particle detector. 12 figs.

Particle detector spatial resolution

DOEpatents

Perez-Mendez, Victor

1992-01-01

Method and apparatus for producing separated columns of scintillation layer material, for use in detection of X-rays and high energy charged particles with improved spatial resolution. A pattern of ridges or projections is formed on one surface of a substrate layer or in a thin polyimide layer, and the scintillation layer is grown at controlled temperature and growth rate on the ridge-containing material. The scintillation material preferentially forms cylinders or columns, separated by gaps conforming to the pattern of ridges, and these columns direct most of the light produced in the scintillation layer along individual columns for subsequent detection in a photodiode layer. The gaps may be filled with a light-absorbing material to further enhance the spatial resolution of the particle detector.

Automated in-line gel filtration for native state mass spectrometry.

PubMed

Waitt, Greg M; Xu, Robert; Wisely, G Bruce; Williams, Jon D

2008-02-01

Characterization of protein-ligand complexes by nondenaturing mass spectrometry provides direct evidence of drug-like molecules binding with potential therapeutic targets. Typically, protein-ligand complexes to be analyzed contain buffer salts, detergents, and other additives to enhance protein solubility, all of which make the sample unable to be analyzed directly by electrospray ionization mass spectrometry. This work describes an in-line gel-filtration method that has been automated and optimized. Automation was achieved using commercial HPLC equipment. Gel column parameters that were optimized include: column dimensions, flow rate, packing material type, particle size, and molecular weight cut-off. Under optimal conditions, desalted protein ions are detected 4 min after injection and the analysis is completed in 20 min. The gel column retains good performance even after >200 injections. A demonstration for using the in-line gel-filtration system is shown for monitoring the exchange of fatty acids from the pocket of a nuclear hormone receptor, peroxisome proliferator activator-delta (PPARdelta) with a tool compound. Additional utilities of in-line gel-filtration mass spectrometry system will also be discussed.

Contribution of benthic microalgae to the temporal variation in phytoplankton assemblages in a macrotidal system.

PubMed

Hernández Fariñas, Tania; Ribeiro, Lourenço; Soudant, Dominique; Belin, Catherine; Bacher, Cédric; Lampert, Luis; Barillé, Laurent

2017-10-01

Suspended marine benthic microalgae in the water column reflect the close relationship between the benthic and pelagic components of coastal ecosystems. In this study, a 12-year phytoplankton time-series was used to investigate the contribution of benthic microalgae to the pelagic system at a site along the French-Atlantic coast. Furthermore, all taxa identified were allocated into different growth forms in order to study their seasonal patterns. The highest contribution of benthic microalgae was observed during the winter period, reaching up to 60% of the carbon biomass in the water column. The haptobenthic growth form showed the highest contribution in terms of biomass, dominant in the fall-winter period when the turbidity and the river flow were high. The epipelic growth form did not follow any seasonal pattern. The epiphytic diatom Licmophora was most commonly found during summer. As benthic microalgae were found in the water column throughout the year, the temporal variation detected in the structure of pelagic assemblages in a macrotidal ecosystem was partly derived from the differentiated contribution of several benthic growth forms. © 2017 Phycological Society of America.

Determination of hexavalent chromium concentration in industrial waste incinerator stack gas by using a modified ion chromatography with post-column derivatization method.

PubMed

Miyake, Yuichi; Tokumura, Masahiro; Iwazaki, Yuta; Wang, Qi; Amagai, Takashi; Horii, Yuichi; Otsuka, Hideyuki; Tanikawa, Noboru; Kobayashi, Takeshi; Oguchi, Masahiro

2017-06-16

An ion chromatography with post-column derivatization with 1,5-diphenylcarbazide (IC-DPC) analytical method was modified to enable measurement of trace-level hexavalent chromium (Cr(VI)) in air. One of the difficulties in determining trace levels of Cr(VI) in air with conventional IC-DPC methods is co-elution of the solvent and ion peaks due to high concentrations of ionic compounds in the extract. However, by using gradient elution rather than isocratic elution we were able to fully resolve the Cr(VI) ion peak from the solvent peak without the need for diluting the extract, which would have reduced the minimum quantifiable level of the method. With this method, we were able to detect Cr(VI) in air at concentrations of 5.3ng/m 3 (assuming a sampling volume of 1m 3 and a final solution volume of 10mL). Recovery tests at three different concentrations of Cr(VI) (50, 250, 1000ng) were performed with or without fly ash; recovery rates at all the concentrations of Cr(VI), with or without fly ash, ranged from 68% to 110% (mean±relative standard deviation, 96%±11%), and there were no differences in recovery rates with respect to the presence or absence of fly ash. Finally, we used the developed method to determine the concentration of Cr(VI) in stack gases collected from eight industrial waste incinerators located in Japan. The concentration of Cr(VI) in the stack gases ranged from below the method quantification limit to 3100ng/m 3 . The highest concentrations of Cr(VI) detected in the stack gases were two to three orders of magnitude higher than that in ambient air in Japan. Copyright © 2017 Elsevier B.V. All rights reserved.

Rugged large volume injection for sensitive capillary LC-MS environmental monitoring

NASA Astrophysics Data System (ADS)

Roberg-Larsen, Hanne; Abele, Silvija; Demir, Deniz; Dzabijeva, Diana; Amundsen, Sunniva F.; Wilson, Steven R.; Bartkevics, Vadims; Lundanes, Elsa

2017-08-01

A rugged and high throughput capillary column (cLC) LC-MS switching platform using large volume injection and on-line automatic filtration and filter back-flush (AFFL) solid phase extraction (SPE) for analysis of environmental water samples with minimal sample preparation is presented. Although narrow columns and on-line sample preparation are used in the platform, high ruggedness is achieved e.g. injection of 100 non-filtrated water samples would did not result in a pressure rise/clogging of the SPE/capillary columns (inner diameter 300 µm). In addition, satisfactory retention time stability and chromatographic resolution were also features of the system. The potential of the platform for environmental water samples was demonstrated with various pharmaceutical products, which had detection limits (LOD) in the 0.05 - 12.5 ng/L range. Between-day and within-day repeatability of selected analytes were < 20% RSD.

Potential of capillary-column-switching liquid chromatography-tandem mass spectrometry for the quantitative trace analysis of small molecules. Application to the on-line screening of drugs in water.

PubMed

Pitarch, Elena; Hernandez, Felix; ten Hove, Jan; Meiring, Hugo; Niesing, Willem; Dijkman, Ellen; Stolker, Linda; Hogendoorn, Elbert

2004-03-26

We have investigated the potential of capillary-column-switching liquid chromatography coupled to tandem mass spectrometry (cLC-MS-MS) for the quantitative on-line trace analysis of target compounds in aqueous solutions. The technical design of the nano-scale cLC system developed at our Institute for peptide and protein identification has been tested and evaluated for the direct trace analysis of drugs in water samples. Sulphametoxazole, bezafibrate, metoprolol, carbamazepine and bisoprolol occurring frequently in Dutch waters, were selected as test compounds. Adequate conditions for trapping, elution and MS-MS detection were investigated by employing laboratory made 200 microm i.d. capillary columns packed with 5 microm aqua C18 material. In the final cLC-MS-MS conditions, a 1 cm length trapping column and a 4 cm length analytical column were selected. Under these conditions, the target compounds could be directly determined in water down to a level of around 50 ng/l employing only 25 microl of water sample. Validation was done by recovery experiments in ground-, surface- and drinking-water matrices as well as by the analysis of water samples with incurred residues and previously analyzed with a conventional procedure involving off-line solid-phase extraction and narrow-bore LC with MS-MS detection. The new methodology provided recoveries (50-500 ng/l level) between 50 and 114% with RSDs (n = 3, each level) below 20% for most of the compounds. Despite the somewhat less analytical performance in comparison to the conventional procedure, the on-line approach of the new methodology is very suitable for screening of drugs in aqueous samples.

Effect of Polyphosphate-accumulating Organisms on Phosphorus Mobility in Variably Saturated Sand Columns

NASA Astrophysics Data System (ADS)

Stockton, M.; Rojas, C.; Regan, J. M.; Saia, S. M.; Buda, A. R.; Carrick, H. J.; Walter, M. T.

2016-12-01

Excessive application of phosphorus-containing fertilizer along with incomplete knowledge about the factors affecting phosphorus transport and mobility has allowed for a growing number of cases of eutrophication in water bodies. Previous research on enhanced biological phosphorus removal (EBPR) systems used in wastewater treatment plants (WWTPs) has identified polyphosphate-accumulating organisms (PAOs) that are known to accumulate and release phosphorus depending on aerobic/anaerobic conditions. Under anaerobic conditions, intracellular polyphosphate (poly-P) bodies are hydrolyzed releasing phosphate, while under aerobic conditions phosphate is taken up and poly-P inclusions are reformed. The presence of PAOs outside of WWTPs has been shown, but their potential impact on phosphorus mobility in other contexts is not as well known. To study that potential impact, sand columns were subjected to alternating cycles of saturation and unsaturation to mimic variably saturated soils and the resultant anaerobic and aerobic conditions that select for PAOs in a WWTP. Pore water samples collected from sterile control columns and columns inoculated with PAOs from a WWTP were compared during each cycle to monitor changes in dissolved inorganic phosphate and total phosphorus concentrations. In addition, continuous redox data were collected to confirm reducing conditions developed during periods of saturation. Sand particles will be subjected to FISH and DAPI staining to visualize PAOs using probes developed for PAOs in EBPR processes and to determine if changes in intracellular poly-P are detectable between the two cycles in the inoculated columns. Studying the effects of PAOs on phosphorus mobility in these controlled column experiments can contribute to understanding phosphorus retention and release by naturally occurring PAOs in terrestrial system, which ultimately can improve the development of management practices that mitigate phosphorus pollution of water bodies.

Validation of an HPLC method for the determination of fleroxacin and its photo-degradation products in pharmaceutical forms.

PubMed

Djurdjevic, Predrag; Laban, Aleksandra; Jelikic-Stankov, Milena

2004-01-01

HPLC determination of fleroxacin in dosage forms was carried out using either reversed-phase column YMC pack ODS-AQ or Supelco LC Hisep shielded hydrophobic phase column, with UV detection at 280 nm. The mobile phase for ODS column consisted of 50:50:0.5 v/v/v and for Hisep column 15:85:0.5 v/v/v acetonitrile-water-triethylamine. The pH of the mobile phase was adjusted to 6.30 for ODS column and to 6.85 for Hisep column, with H3PO4. Linear response was obtained in the concentration range of fleroxacin between 0.01 and 1.30 micrograms/mL. Detection limit was 4.8 ng/mL. Recovery test in the determination of fleroxacin in "Quinodis" tablets (Hoffmann La Roche, nominal mass 400 or 200 mg) was 98-101% for both columns. The effect of the composition and pH of the mobile phase on spectra, retention time and dissociation constants of fleroxacin was discussed. The proposed method could be also used for separation of the photo-degradation products of fleroxacin. Ten degradation products were separated on the ODS-AQ column, thus confirming the suitability of the proposed method for stability study of fleroxacin in pharmaceuticals.

Numerical Study on Section Constitutive Relations of Members Reinforced by Steel-BFRP Composite Bars

NASA Astrophysics Data System (ADS)

Xiao, Tongliang; Qiu, Hongxing

2017-06-01

Steel-Basalt FRP Composite Bar (S-BFCB) is a new kind of substitute material for longitudinal reinforcement, with high elastic modulus, stable post-yield stiffness and excellent corrosive resistance. Based on mechanical properties of S-BFCB and the plane cross-section assumption, the moment-curvature curves of beam and column members are simulated. Some parameters such as equivalent rebar ratio, postyeild stiffness, concrete strength and axial compression ratio of column were discussed. Results show that the constitutive relation of the cross section is similar with RC member in elastic and cracking stages, while different in post-yield stage. With the increase of postyeild stiffness ratio of composite bar, the ultimate bearing capacity of component improved observably, member may turn out over-reinforced phenomenon, concrete crushing may appear before the fibersarefractured. The effect of concrete strength increase in lower postyeild stiffness ratio is not obvious than in higher. The increase of axial compression ratio has actively influence on bearing capacity of column, but decreases on the ductility.

The ability of endotoxin adsorption during a longer duration of direct hemoperfusion with a polymyxin B-immobilized fiber column in patients with septic shock.

PubMed

Shimizu, Tomoharu; Obata, Toru; Sonoda, Hiromichi; Akabori, Hiroya; Tabata, Takahisa; Eguchi, Yutaka; Endo, Yoshihiro; Tani, Tohru

2013-12-01

The patients' hemodynamic conditions of septic shock due to intra-abdominal infection were improved by the longer duration of direct hemoperfusion with a polymyxin B-immobilized fiber column (PMX), reducing plasma endotoxins measured by the novel endotoxin detection method, named endotoxin scattering photometry (ESP) method; however, turbidimetric method could not detect endotoxins. We also observed the reduction in the endotoxin after passing through column by ESP method even after the longer duration of PMX. ESP method may more sensitively detect endotoxins than the ordinary turbidimetric method. Moreover, we demonstrated the ability of endotoxin adsorption in spite of the longer duration of PMX. Copyright © 2013 Elsevier Ltd. All rights reserved.

The analysis of carbohydrates in milk powder by a new "heart-cutting" two-dimensional liquid chromatography method.

PubMed

Ma, Jing; Hou, Xiaofang; Zhang, Bing; Wang, Yunan; He, Langchong

2014-03-01

In this study, a new"heart-cutting" two-dimensional liquid chromatography method for the simultaneous determination of carbohydrate contents in milk powder was presented. In this two dimensional liquid chromatography system, a Venusil XBP-C4 analysis column was used in the first dimension ((1)D) as a pre-separation column, a ZORBAX carbohydrates analysis column was used in the second dimension ((2)D) as a final-analysis column. The whole process was completed in less than 35min without a particular sample preparation procedure. The capability of the new two dimensional HPLC method was demonstrated in the determination of carbohydrates in various brands of milk powder samples. A conventional one dimensional chromatography method was also proposed. The two proposed methods were both validated in terms of linearity, limits of detection, accuracy and precision. The comparison between the results obtained with the two methods showed that the new and completely automated two dimensional liquid chromatography method is more suitable for milk powder sample because of its online cleanup effect involved. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

Chip-based molecularly imprinted monolithic capillary array columns coated GO/SiO2 for selective extraction and sensitive determination of rhodamine B in chili powder.

PubMed

Zhai, Haiyun; Huang, Lu; Chen, Zuanguang; Su, Zihao; Yuan, Kaisong; Liang, Guohuan; Pan, Yufang

2017-01-01

A novel solid-phase extraction chip embedded with array columns of molecularly imprinted polymer-coated silanized graphene oxide (GO/SiO2-MISPE) was established to detect trace rhodamine B (RB) in chili powder. GO/SiO2-MISPE monolithic columns for RB detection were prepared by optimizing the supporting substrate, template, and polymerizing monomer under mild water bath conditions. Adsorption capacity and specificity, which are critical properties for the application of the GO/SiO2-MISPE monolithic column, were investigated. GO/SiO2-MIP was examined by scanning electron microscopy (SEM) and Fourier transform-infrared spectroscopy. The recovery and the intraday and interday relative standard deviations for RB ranged from 83.7% to 88.4% and 2.5% to 4.0% and the enrichment factors were higher than 110-fold. The chip-based array columns effectively eliminated impurities in chili powder, indicating that the chip-based GO/SiO2-MISPE method was reliable for RB detection in food samples using high-performance liquid chromatography. Accordingly, this method has direct applications for monitoring potentially harmful dyes in processed food. Copyright © 2016 Elsevier Ltd. All rights reserved.

Virus movement in soil columns flooded with secondary sewage effluent.

PubMed Central

Lance, J C; Gerba, C P; Melnick, J L

1976-01-01

Secondary sewage effluent containing about 3 X 10(4) plaque-forming units of polio virus type 1 (LSc) per ml was passed through columns 250 cm in length packed with calcareous sand from an area in the Salt River bed used for ground-water recharge of secondary sewage effluent. Viruses were not detected in 1-ml samples extracted from the columns below the 160-cm level. However, viruses were detected in 5 of 43 100-ml samples of the column drainage water. Most of the viruses were adsorbed in the top 5 cm of soil. Virus removal was not affected by the infiltration rate, which varied between 15 and 55 cm/day. Flooding a column continuosly for 27 days with the sewage water virus mixture did not saturate the top few centimeters of soil with viruses and did not seem to affect virus movement. Flooding with deionized water caused virus desorption from the soil and increased their movement through the columns. Adding CaCl2 to the deionized water prevented most of the virus desorption. Adding a pulse of deionized water followed by sewage water started a virus front moving through the columns, but the viruses were readsorbed and none was detected in outflow samples. Drying the soil for 1 day between applying the virus and flooding with deionized water greatly reduced desorption, and drying for 5 days prevented desorption. Large reductions (99.99% or more) of virus would be expected after passage of secondary sewage effluent through 250 cm of the calcareous sand similar to that used in our laboratory columns unless heavy rains fell within 1 day after the application of sewage stopped. Such virus movement could be minimized by the proper management of flooding and drying cycles. PMID:185960

Preparation of epoxy-based macroporous monolithic columns for the fast and efficient immunofiltration of Staphylococcus aureus.

PubMed

Ott, Sonja; Niessner, Reinhard; Seidel, Michael

2011-08-01

Macroporous epoxy-based monolithic columns were used for immunofiltration of bacteria. The prepared monolithic polymer support is hydrophilic and has large pore sizes of 21 μm without mesopores. A surface chemistry usually applied for immobilization of antibodies on glass slides is successfully transferred to monolithic columns. Step-by-step, the surface of the epoxy-based monolith is hydrolyzed, silanized, coated with poly(ethylene glycol diamine) and activated with the homobifunctional crosslinker di(N-succinimidyl)carbonate for immobilization of antibodies on the monolithic columns. The functionalization steps are characterized to ensure the coating of each monolayer. The prepared antibody-immobilized monolithic column is optimized for immunofiltration to enrich Staphylococcus aureus as an important food contaminant. Different kinds of geometries of monolithic columns, flow rates and elution buffers are tested with the goal to get high recoveries in the shortest enrichment time as possible. An effective capture of S. aureus was achieved at a flow rate of 7.0 mL/min with low backpressures of 20.1±5.4 mbar enabling a volumetric enrichment of 1000 within 145 min. The bacteria were quantified by flow cytometry using a double-labeling approach. After immunofiltration the sensitivity was significantly increased and a detection limit of the total system of 42 S. aureus/mL was reached. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Systems for column-based separations, methods of forming packed columns, and methods of purifying sample components

DOEpatents

Egorov, Oleg B.; O'Hara, Matthew J.; Grate, Jay W.; Chandler, Darrell P.; Brockman, Fred J.; Bruckner-Lea, Cynthia J.

2000-01-01

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber. In another aspect, the invention includes a system for column-based separations, comprising: a) a fluid passageway, the fluid passageway comprising a column chamber and a flow path in fluid communication with the column chamber, the flow path being obstructed by a retaining material permeable to a carrier fluid and impermeable to a column matrix material suspended in the carrier fluid, the flow path extending through the column chamber and through the retaining material, the flow path being configured to form a packed column within the column chamber when a suspension of the fluid and the column matrix material is flowed along the flow path; and b) the fluid passageway extending through a valve intermediate the column chamber and the retaining material.

Systems For Column-Based Separations, Methods Of Forming Packed Columns, And Methods Of Purifying Sample Components

DOEpatents

Egorov, Oleg B.; O'Hara, Matthew J.; Grate, Jay W.; Chandler, Darrell P.; Brockman, Fred J.; Bruckner-Lea, Cynthia J.

2006-02-21

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber. In another aspect, the invention includes a system for column-based separations, comprising: a) a fluid passageway, the fluid passageway comprising a column chamber and a flow path in fluid communication with the column chamber, the flow path being obstructed by a retaining material permeable to a carrier fluid and impermeable to a column matrix material suspended in the carrier fluid, the flow path extending through the column chamber and through the retaining material, the flow path being configured to form a packed column within the column chamber when a suspension of the fluid and the column matrix material is flowed along the flow path; and b) the fluid passageway extending through a valve intermediate the column chamber and the retaining material.

Systems For Column-Based Separations, Methods Of Forming Packed Columns, And Methods Of Purifying Sample Components.

DOEpatents

Egorov, Oleg B.; O'Hara, Matthew J.; Grate, Jay W.; Chandler, Darrell P.; Brockman, Fred J.; Bruckner-Lea, Cynthia J.

2004-08-24

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber. In another aspect, the invention includes a system for column-based separations, comprising: a) a fluid passageway, the fluid passageway comprising a column chamber and a flow path in fluid communication with the column chamber, the flow path being obstructed by a retaining material permeable to a carrier fluid and impermeable to a column matrix material suspended in the carrier fluid, the flow path extending through the column chamber and through the retaining material, the flow path being configured to form a packed column within the column chamber when a suspension of the fluid and the column matrix material is flowed along the flow path; and b) the fluid passageway extending through a valve intermediate the column chamber and the retaining material.

Derivative spectrum chromatographic method for the determination of trimethoprim in honey samples using an on-line solid-phase extraction technique.

PubMed

Uchiyama, Kazuhisa; Kondo, Mari; Yokochi, Rika; Takeuchi, Yuri; Yamamoto, Atsushi; Inoue, Yoshinori

2011-07-01

A simple, selective and rapid analytical method for determination of trimethoprim (TMP) in honey samples was developed and validated. This method is based on a SPE technique followed by HPLC with photodiode array detection. After dilution and filtration, aliquots of 500 μL honey samples were directly injected to an on-line SPE HPLC system. TMP was extracted on an RP SPE column, and separated on a hydrophilic interaction chromatography column during HPLC analysis. At the first detection step, the noise level of the photodiode array data was reduced with two-dimensional equalizer filtering, and then the smoothed data were subjected to derivative spectrum chromatography. On the second-derivative chromatogram at 254 nm, the limit of detection and the limit of quantification of TMP in a honey sample were 5 and 10 ng/g, respectively. The proposed method showed high accuracy (60-103%) with adequate sensitivity for TMP monitoring in honey samples. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Non-detection of HC11N towards TMC-1: constraining the chemistry of large carbon-chain molecules

NASA Astrophysics Data System (ADS)

Loomis, Ryan A.; Shingledecker, Christopher N.; Langston, Glen; McGuire, Brett A.; Dollhopf, Niklaus M.; Burkhardt, Andrew M.; Corby, Joanna; Booth, Shawn T.; Carroll, P. Brandon; Turner, Barry; Remijan, Anthony J.

2016-12-01

Bell et al. reported the first detection of the cyanopolyyne HC11N towards the cold dark cloud TMC-1; no subsequent detections have been reported towards any source. Additional observations of cyanopolyynes and other carbon-chain molecules towards TMC-1 have shown a log-linear trend between molecule size and column density, and in an effort to further explore the underlying chemical processes driving this trend, we have analysed Green Bank Telescope observations of HC9N and HC11N towards TMC-1. Although we find an HC9N column density consistent with previous values, HC11N is not detected and we derive an upper limit column density significantly below that reported in Bell et al. Using a state-of-the-art chemical model, we have investigated possible explanations of non-linearity in the column density trend. Despite updating the chemical model to better account for ion-dipole interactions, we are not able to explain the non-detection of HC11N, and we interpret this as evidence of previously unknown carbon-chain chemistry. We propose that cyclization reactions may be responsible for the depleted HC11N abundance, and that products of these cyclization reactions should be investigated as candidate interstellar molecules.

[Immunoaffinity columns and determination of ochratoxin A in cereals by HPLC. Part I.: Evaluation of extraction using methanol/water].

PubMed

Czerwiecki, Ludwik; Czyzyk, Kamila; Kwiecień, Agnieszka; Wilczyńska, Grazyna

2004-01-01

The method for ochratoxin A determination in cereals (wheat, rye) was described. Application of immunoaffinity columns (IAC) for clean-up of extracts was investigated. The ochratoxin A content was determined by high-performance liquid chromatography using C18 column and fluorimetric detection at 330 nm (excitation) and 460 nm (emission). The mean recovery of ochratoxin A was 65-78%. The limits of detection (LOD) and quantification (LOQ) were 0.015 and 0.025 microg/kg, respectively. The positive results were confirmed by reaction with BF3 complex in methanol.

FRACTIONATING COLUMN PRODUCT COLLECTOR CONTROL

DOEpatents

Paxson, G.D. Jr.

1964-03-10

Means for detecting minute fluid products from a chemical separation column and for advancing a collector tube rack in order to automatically separate and collect successive fractionated products are described. A charge is imposed on the forming drops at the column orifice to create an electric field as the drop falls in the vicinity of a sensing plate. The field is detected by an electrometer tube coupled to the plate causing an output signal to actuate rotation of a collector turntable rack, thereby positioning new collectors under the orifice. The invention provides reliable automatic collection independent of drop size, rate of fall, or chemical composition. (AEC)

Investigating the real translucency of the endodontic fiber posts

NASA Astrophysics Data System (ADS)

Camilotti, Fernando; Bonardi, Cláudia; Somer, Aloisi; Novatski, Andressa; Szesz, Anna Luiza; Loguércio, Alessandro Dourado; Kniphoff da Cruz, Gerson

2018-02-01

Researchers have been investigating the light intensity scattered by a translucent fiber post with application in dentistry by different methods. In this work, we introduce a new system capable to record a light scattered profile, step-by-step, as a function of the length of the translucent fiber post. To support our studies, an extensive characterization of the system was carried out and this is presented and discussed here. The system was implemented using the phase sensitive detection. The equipment measures the light scattered without the need of any preparing parts and the fiber post is fixed directly in the fiber post holder becoming ready for measurement. Measures can be recorded with a spatial resolution smaller than 0.01 mm throughout the length of the fiber post being investigated. The system was implemented by using a photomultiplier tube that improves sensitivity for the optical detection. The recorded result is a signal directly proportional to the scattered light and it allows us to obtain a normalized profile that can be used as a map of the scattered light of the fiber post in study. Furthermore, we are able to demonstrate a low intensity of light in the tip region of the fiber post, along with the dependency of the light attenuation with the fiber post body volume and shape. This new system will certainly contribute to achieve better results in fiber post designing and in restoration of endodontic treated teeth because it provides a more well-founded choice of the fiber post to be used, and of the time of exposure to the curing light.

40 CFR 264.310 - Closure and post-closure care.

Code of Federal Regulations, 2010 CFR

2010-07-01

... settling, subsidence, erosion, or other events; (2) Continue to operate the leachate collection and removal system until leachate is no longer detected; (3) Maintain and monitor the leak detection system in...

40 CFR 264.310 - Closure and post-closure care.

Code of Federal Regulations, 2012 CFR

2012-07-01

... settling, subsidence, erosion, or other events; (2) Continue to operate the leachate collection and removal system until leachate is no longer detected; (3) Maintain and monitor the leak detection system in...

40 CFR 264.310 - Closure and post-closure care.

Code of Federal Regulations, 2013 CFR

2013-07-01

... settling, subsidence, erosion, or other events; (2) Continue to operate the leachate collection and removal system until leachate is no longer detected; (3) Maintain and monitor the leak detection system in...

40 CFR 264.310 - Closure and post-closure care.

Code of Federal Regulations, 2014 CFR

2014-07-01

... settling, subsidence, erosion, or other events; (2) Continue to operate the leachate collection and removal system until leachate is no longer detected; (3) Maintain and monitor the leak detection system in...

40 CFR 264.310 - Closure and post-closure care.

Code of Federal Regulations, 2011 CFR

2011-07-01

... settling, subsidence, erosion, or other events; (2) Continue to operate the leachate collection and removal system until leachate is no longer detected; (3) Maintain and monitor the leak detection system in...

Stereospecific analysis of loxoprofen in plasma by chiral column liquid chromatography with a circular dichroism-based detector.

PubMed

Kanazawa, Hideko; Tsubayashi, Akane; Nagata, Yoshiko; Matsushima, Yoshikazu; Mori, Chiharu; Kizu, Junko; Higaki, Megumu

2002-03-01

The chiral separation of loxoprofen was achieved on a chiral column with UV and circular dichroism (CD) detection. The good resolution of four loxoprofen stereoisomers was obtained. The column used for the chiral separation was Chiralcel OJ column (250 x 4.6 mm) using hexane-2-propanol-trifluoroacetic acid (95:5:0.1), as an eluent. The flow-rate was 1.0 ml/min and the detection was at 225 nm. In addition, CD and UV spectra were obtained by stopped flow scanning. The method allows the determination of the stereoisomers of loxoprofen in human plasma after the administration of therapeutic dose of the racemic drug, thus HPLC with CD detector is useful for the stereospecific determination of loxoprofen products in biological samples.

Recent advances in liquid and gas chromatography methodology for extending coverage of the metabolome.

PubMed

Haggarty, Jennifer; Burgess, Karl Ev

2017-02-01

The metabolome is the complete complement of metabolites (small organic biomolecules). In order to comprehensively understand the effect of stimuli on a biological system, it is important to detect as many of the metabolites within that system as possible. This review briefly describes some new advances in liquid and gas chromatography to improve coverage of the metabolome, including the serial combination of two columns in tandem, column switching and different variations of two-dimensional chromatography. Supercritical fluid chromatography could provide complimentary data to liquid and gas chromatography. Although there have been many recent advancements in the field of metabolomics, it is evident that a combination, rather than a single method, is required to approach full coverage of the metabolome. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Phototoxicity testing by online irradiation and HPLC.

PubMed

Schröder, Sven; Surmann, J P

2006-11-01

A high-performance liquid chromatography (HPLC) system was developed for the determination of drug photostability and phototoxicity based on an automated column-switching system with aqueous online UV-A irradiation and hyphenated organic separation of the drug and its photoproducts. The photoreactor is built with an poly(ethylene-co-tetrafluoroethylene) (ETFE) reaction coil knitted around a UV-A light source. The chromatographic separation was performed with two special C18 columns, which are also suitable for using with pure water as eluent. Degradation of chlorpromazine (CPZ) by ultraviolet light was investigated at pH 7 and pH 3. Furthermore chlorpromazine was irradiated in the presence of guanosine-5-monophosphate (GMP) in pH 7 buffered solution, leading to a new photoproduct. In the pH 3 irradiation studies of CPZ and GMP, no reaction was detected between the molecules.

Do pharmaceuticals, pathogens, and other organic waste water compounds persist when waste water is used for recharge?

USGS Publications Warehouse

Cordy, Gail E.; Duran, Norma L.; Bouwer, Herman; Rice, Robert C.; Furlong, Edward T.; Zaugg, Steven D.; Meyer, Michael T.; Barber, Larry B.; Kolpin, Dana W.

2004-01-01

A proof-of-concept experiment was devised to determine if pharmaceuticals and other organic waste water compounds (OWCs), as well as pathogens, found in treated effluent could be transported through a 2.4 m soil column and, thus, potentially reach ground water under recharge conditions similar to those in arid or semiarid climates. Treated effluent was applied at the top of the 2.4 m long, 32.5 cm diameter soil column over 23 days, Samples of the column inflow were collected from the effluent storage tank at the beginning (Tbegin) and end (Tend) of the experiment, and a sample of the soil column drainage at the base of the column (Bend) was collected at the end of the experiment. Samples were analyzed for 131 OWCs including veterinary and human antibiotics, other prescription and nonprescription drugs, widely used household and industrial chemicals, and steroids and reproductive hormones, as well as the pathogens Salmonella and Legionella. Analytical results for the two effluent samples taken at the beginning (Tbegin) and end (Tend) of the experiment indicate that the number of OWCs detected in the column inflow decreased by 25% (eight compounds) and the total concentration of OWCs decreased by 46% while the effluent was in the storage tank during the 23-day experiment. After percolating through the soil column, an additional 18 compounds detected in Tend (67% of OWCs) were no longer detected in the effluent (Bend) and the total concentration of OWCs decreased by more than 70%. These compounds may have been subject to transformation (biotic and abiotic), adsorption, and (or) volatilization in the storage tank and during travel through the soil column. Eight compounds—carbamazapine; sulfamethoxazole; benzophenone; 5-methyl-1H-benzotriazole; N,N-diethyltoluamide; tributylphosphate; tri(2-chloroethyl) phosphate; and cholesterol—were detected in all three samples indicating they have the potential to reach ground water under recharge conditions similar to those in arid and semiarid climates. Results from real-time polymerase chain reactions demonstrated the presence of Legionella in all three samples. Salmonella was detected only in Tbegin, suggesting that the bacteria died off in the effluent storage tank over the period of the experiment. This proof-of-concept experiment demonstrates that, under recharge conditions similar to those in arid or semiarid climates, some pharmaceuticals, pathogens, and other OWCs can persist in treated effluent after soil-aquifer treatment.

SU-E-J-81: Beveled Needle Tip Detection Error in Ultrasound-Guided Prostate Brachytherapy.

PubMed

Leu, S; Ruiz, B; Podder, T

2012-06-01

To quantify the needle tip detection errors in ultrasound images due to bevel-tip orientation in relation to the location on template grid. Transrectal ultrasound (TRUS) system (BK Medical) with physical template grid and 18-gauge bevel-tip (20-deg beveled angle) brachytherapy needle (Bard Medical, Covington, GA) were used. The TRUS was set at 6.5MHz in water phantom at 40°C and measurements were taken with 50% and 100% TRUS gains. Needles were oriented with bevel-tip facing up (0-degree) and inserted through template grid-holes. Reference needle depths were measured when needle tip image intensity was bright enough for potentially consistent readings. High-resolution digital vernier caliper was used to measure needle depth. Needle bevel-tip orientation was then changed to bevel down (by rotating 180-degree) and needle depth was adjusted by retracting so that the needle-tip image intensity appeared similar to when the needle bevel-tip was at 0-degree orientation. Clinically relevant locations were considered for needle placement on the template grids (1st row to 9th row, and 'a-f' columns). For 50% TRUS gain, bevel tip detection errors/differences were 0.69±0.30mm (1st row) to 3.23±0.22mm (9th row) and 0.78±0.71mm (1st row) to 4.14±0.56mm (9th row) in columns 'a' and 'D', respectively. The corresponding errors for 100% TRUS gain were 0.57±0.25mm to 5.24±0.36mm and 0.84±0.30mm to 4.2±0.20mm in columns 'a' and 'D', respectively. These errors/differences varied linearly for grid-hole locations on the rows and columns in between, smaller to large depending on distance from the TRUS probe. Observed no effect of gains (50% vs. 100%) along 'D' column, which was directly above the TRUS probe. Experiment results revealed that the beveled needle tip orientation could significantly impact the detection accuracy of the needle tips, based on which the seeds might be delivered. These errors may lead to considerable dosimetric deviations in prostate brachytherapy seed implantation. © 2012 American Association of Physicists in Medicine.

C(18) columns for the simultaneous determination of oxytetracycline and its related substances by reversed-phase high performance liquid chromatography and UV detection.

PubMed

Smyrniotakis, C G; Archontaki, Helen A

2007-01-17

Simultaneous determination of oxytetracycline, 4-epioxytetracycline, alpha-apooxytetracycline, tetracycline and beta-apooxytetracycline on C(18) columns has been accomplished using a high performance liquid chromatographic method with UV detection. Separation was achieved on a Hypersil BDS RP-C(18) column (250 mm x 4.6 mm) and on a Waters C(18) Symmetry column (150 mm x 3.9mm), 5 microm particle size each. These columns were equilibrated with mobile phases consisted of methanol-acetonitrile-0.1M phosphate buffer pH 8.0 (12.5:12.5:75, v/v/v) and (15:15:70, v/v/v), respectively. The flow rate was 1.0 ml/min and the total elution time was 15 and 5 min, respectively. Both methods were applied to oxytetracycline raw material, human and veterinary formulations, where the excipients did not interfere. External standard calibration curves were linear for 4-epioxytetracycline, oxytetracycline, alpha-apooxytetracycline, tetracycline and beta-apooxytetracycline in the concentration range of 0.27-200 microM, 0.05-200 microM, 0.03-200 microM, 0.35-200 microM and 0.20-200 microM on column A and 0.08-200 microM, 0.15-200 microM, 0.09-200 microM, 0.25-200 microM and 0.47-200 microM on column B, respectively. Day-to-day relative standard deviation of the determination for every component was less than 3%. Concerning the first column, limits of detection and quantification of the above compounds were in the concentration ranges of 10-106 nM and 30-352 nM, respectively, whereas on the second column these ranges became 27-144 nM and 81-475 nM, respectively. Recovery of the separated compounds was 95-105%.

On the Unreasonable Effectiveness of post-Newtonian Theory in Gravitational-Wave Physics

ScienceCinema

Will, Clifford M.

2017-12-22

The first indirect detection of gravitational waves involved a binary system of neutron stars.  In the future, the first direct detection may also involve binary systems -- inspiralling and merging binary neutron stars or black holes. This means that it is essential to understand in full detail the two-body system in general relativity, a notoriously difficult problem with a long history. Post-Newtonian approximation methods are thought to work only under slow motion and weak field conditions, while numerical solutions of Einstein's equations are thought to be limited to the final merger phase.  Recent results have shown that post-Newtonian approximations seem to remain unreasonably valid well into the relativistic regime, while advances in numerical relativity now permit solutions for numerous orbits before merger.  It is now possible to envision linking post-Newtonian theory and numerical relativity to obtain a complete "solution" of the general relativistic two-body problem.  These solutions will play a central role in detecting and understanding gravitational wave signals received by interferometric observatories on Earth and in space.

Comparison of twin-cell centrifugal partition chromatographic columns with different cell volume.

PubMed

Goll, Johannes; Audo, Gregoire; Minceva, Mirjana

2015-08-07

Two twin-cell centrifugal partition chromatographic columns (SCPC 250 and SCPE-250-BIO, Armen Instrument, France) with the same column volume but different cell size and number were compared in terms of stationary phase retention and column efficiency. The columns were tested with two types of solvent systems: a commonly used organic solvent based biphasic system from the ARIZONA solvent system family and a polymer/salt based aqueous two phase system (ATPS). The efficiency of the columns was evaluated by pulse injection experiments of two benzenediols (pyrocatechol and hydroquinone) in the case of the ARIZONA system and a protein mixture (myoglobin and lysozyme) in the case of the ATPS. As result of high stationary phase retention, the column with the lower number of larger twin-cells (SCPE-250-BIO) is suitable for protein separations using ATPS. On the other hand, due to higher column efficiency, the column with the greater number of smaller cells (SCPC 250) is superior for batch elution separations performed with standard liquid-liquid chromatography organic solvent based biphasic systems. Copyright © 2015 Elsevier B.V. All rights reserved.

Comparison of salivary collection and processing methods for quantitative HHV-8 detection.

PubMed

Speicher, D J; Johnson, N W

2014-10-01

Saliva is a proved diagnostic fluid for the qualitative detection of infectious agents, but the accuracy of viral load determinations is unknown. Stabilising fluids impede nucleic acid degradation, compared with collection onto ice and then freezing, and we have shown that the DNA Genotek P-021 prototype kit (P-021) can produce high-quality DNA after 14 months of storage at room temperature. Here we evaluate the quantitative capability of 10 collection/processing methods. Unstimulated whole mouth fluid was spiked with a mixture of HHV-8 cloned constructs, 10-fold serial dilutions were produced, and samples were extracted and then examined with quantitative PCR (qPCR). Calibration curves were compared by linear regression and qPCR dynamics. All methods extracted with commercial spin columns produced linear calibration curves with large dynamic range and gave accurate viral loads. Ethanol precipitation of the P-021 does not produce a linear standard curve, and virus is lost in the cell pellet. DNA extractions from the P-021 using commercial spin columns produced linear standard curves with wide dynamic range and excellent limit of detection. When extracted with spin columns, the P-021 enables accurate viral loads down to 23 copies μl(-1) DNA. The quantitative and long-term storage capability of this system makes it ideal for study of salivary DNA viruses in resource-poor settings. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Development of capillary electrophoresis methods for quantitative determination of taurine in vehicle system and biological media.

PubMed

da Silva, Dayse L P; Rüttinger, Hans H; Mrestani, Yahia; Baum, Walter F; Neubert, Reinhard H H

2006-06-01

CE methods have been developed for the determination of taurine in pharmaceutical formulation (microemulsion) and in biological media such as sweat. The CE system with end-column pulsed amperometric detection has been found to be an interesting method in comparison with UV and fluorescence detection for its simplicity and rapidity. A gold-disk electrode of 100 mm diameter was used as the working electrode. The effects of a field decoupler at the end of the capillary, separation voltage, injection and pressure times were investigated. A detection limit of 4 x 10(-5) mol/L was reached using integrated pulsed amperometric detection, a method successfully applied to taurine analysis of the biological samples such as sweat. For taurine analysis of oil-in-water microemulsion, fluorescence detector was the favored method, the detection limit of which was 4 x 10(-11) mol/L.

Development and application of a high-performance liquid chromatography method using monolithic columns for the analysis of ecstasy tablets.

PubMed

Mc Fadden, Kim; Gillespie, John; Carney, Brian; O'Driscoll, Daniel

2006-07-07

A rapid and selective HPLC method using monolithic columns was developed for the separation and quantification of the principal amphetamines in ecstasy tablets. Three monolithic (Chromolith RP18e) columns of different lengths (25, 50 and 100 mm) were assessed. Validation studies including linearity, selectivity, precision, accuracy and limit of detection and quantification were carried out using the Chromolith SpeedROD, RP-18e, 50 mm x 4.6 mm column. Column backpressure and van Deemter plots demonstrated that monolithic columns provide higher efficiency at higher flow rates when compared to particulate columns without the loss of peak resolution. Application of the monolithic column to a large number of ecstasy tablets seized in Ireland ensured its suitability for the routine analysis of ecstasy tablets.

Rapid quantification of underivatized amino acids in plasma by hydrophilic interaction liquid chromatography (HILIC) coupled with tandem mass-spectrometry.

PubMed

Prinsen, Hubertus C M T; Schiebergen-Bronkhorst, B G M; Roeleveld, M W; Jans, J J M; de Sain-van der Velden, M G M; Visser, G; van Hasselt, P M; Verhoeven-Duif, N M

2016-09-01

Amino acidopathies are a class of inborn errors of metabolism (IEM) that can be diagnosed by analysis of amino acids (AA) in plasma. Current strategies for AA analysis include cation exchange HPLC with post-column ninhydrin derivatization, GC-MS, and LC-MS/MS-related methods. Major drawbacks of the current methods are time-consuming procedures, derivative problems, problems with retention, and MS-sensitivity. The use of hydrophilic interaction liquid chromatography (HILIC) columns is an ideal separation mode for hydrophilic compounds like AA. Here we report a HILIC-method for analysis of 36 underivatized AA in plasma to detect defects in AA metabolism that overcomes the major drawbacks of other methods. A rapid, sensitive, and specific method was developed for the analysis of AA in plasma without derivatization using HILIC coupled with tandem mass-spectrometry (Xevo TQ, Waters). Excellent separation of 36 AA (24 quantitative/12 qualitative) in plasma was achieved on an Acquity BEH Amide column (2.1×100 mm, 1.7 μm) in a single MS run of 18 min. Plasma of patients with a known IEM in AA metabolism was analyzed and all patients were correctly identified. The reported method analyzes 36 AA in plasma within 18 min and provides baseline separation of isomeric AA such as leucine and isoleucine. No separation was obtained for isoleucine and allo-isoleucine. The method is applicable to study defects in AA metabolism in plasma.

Information or resolution: Which is required from an SEM to study bulk inorganic materials?: Evaluate SEMs’ practical performance

DOE PAGES

Xing, Q.

2016-07-11

Significant technological advances in scanning electron microscopy (SEM) have been achieved over the past years. Different SEMs can have significant differences in functionality and performance. This work presents the perspectives on selecting an SEM for research on bulk inorganic materials. Understanding materials demands quantitative composition and orientation information, and informative and interpretable images that reveal subtle differences in chemistry, orientation/structure, topography, and electronic structure. The capability to yield informative and interpretable images with high signal-to-noise ratios and spatial resolutions is an overall result of the SEM system as a whole, from the electron optical column to the detection system. Themore » electron optical column determines probe performance. The roles of the detection system are to capture, filter or discriminate, and convert signal electrons to imaging information. The capability to control practical operating parameters including electron probe size and current, acceleration voltage or landing voltage, working distance, detector selection, and signal filtration is inherently determined by the SEM itself. As a platform for various accessories, e.g. an energydispersive spectrometer and an electron backscatter diffraction detector, the properties of the electron optical column, specimen chamber, and stage greatly affect the performance of accessories. Ease-of-use and ease-of-maintenance are of practical importance. It is practically important to select appropriate test specimens, design suitable imaging conditions, and analyze the specimen chamber geometry and dimensions to assess the overall functionality and performance of an SEM. Finally, for an SEM that is controlled/operated with a computer, the stable software and user-friendly interface significantly affect the usability of the SEM.« less

Annotation of the human serum metabolome by coupling three liquid chromatography methods to high-resolution mass spectrometry.

PubMed

Boudah, Samia; Olivier, Marie-Françoise; Aros-Calt, Sandrine; Oliveira, Lydie; Fenaille, François; Tabet, Jean-Claude; Junot, Christophe

2014-09-01

This work aims at evaluating the relevance and versatility of liquid chromatography coupled to high resolution mass spectrometry (LC/HRMS) for performing a qualitative and comprehensive study of the human serum metabolome. To this end, three different chromatographic systems based on a reversed phase (RP), hydrophilic interaction chromatography (HILIC) and a pentafluorophenylpropyl (PFPP) stationary phase were used, with detection in both positive and negative electrospray modes. LC/HRMS platforms were first assessed for their ability to detect, retain and separate 657 metabolite standards representative of the chemical families occurring in biological fluids. More than 75% were efficiently retained in either one LC-condition and less than 5% were exclusively retained by the RP column. These three LC/HRMS systems were then evaluated for their coverage of serum metabolome. The combination of RP, HILIC and PFPP based LC/HRMS methods resulted in the annotation of about 1328 features in the negative ionization mode, and 1358 in the positive ionization mode on the basis of their accurate mass and precise retention time in at least one chromatographic condition. Less than 12% of these annotations were shared by the three LC systems, which highlights their complementarity. HILIC column ensured the greatest metabolome coverage in the negative ionization mode, whereas PFPP column was the most effective in the positive ionization mode. Altogether, 192 annotations were confirmed using our spectral database and 74 others by performing MS/MS experiments. This resulted in the formal or putative identification of 266 metabolites, among which 59 are reported for the first time in human serum. Copyright © 2014 Elsevier B.V. All rights reserved.

Information or resolution: Which is required from an SEM to study bulk inorganic materials?

PubMed

Xing, Q

2016-11-01

Significant technological advances in scanning electron microscopy (SEM) have been achieved over the past years. Different SEMs can have significant differences in functionality and performance. This work presents the perspectives on selecting an SEM for research on bulk inorganic materials. Understanding materials demands quantitative composition and orientation information, and informative and interpretable images that reveal subtle differences in chemistry, orientation/structure, topography, and electronic structure. The capability to yield informative and interpretable images with high signal-to-noise ratios and spatial resolutions is an overall result of the SEM system as a whole, from the electron optical column to the detection system. The electron optical column determines probe performance. The roles of the detection system are to capture, filter or discriminate, and convert signal electrons to imaging information. The capability to control practical operating parameters including electron probe size and current, acceleration voltage or landing voltage, working distance, detector selection, and signal filtration is inherently determined by the SEM itself. As a platform for various accessories, e.g. an energy-dispersive spectrometer and an electron backscatter diffraction detector, the properties of the electron optical column, specimen chamber, and stage greatly affect the performance of accessories. Ease-of-use and ease-of-maintenance are of practical importance. It is practically important to select appropriate test specimens, design suitable imaging conditions, and analyze the specimen chamber geometry and dimensions to assess the overall functionality and performance of an SEM. For an SEM that is controlled/operated with a computer, the stable software and user-friendly interface significantly improve the usability of the SEM. SCANNING 38:864-879, 2016. © 2016 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

Determination of available phosphorus in soils by using a new extraction procedure and a flow injection amperometric system.

PubMed

Jakmunee, Jaroon; Junsomboon, Jaroon

2009-09-15

A new extraction procedure based on an off-line extraction column was proposed for extracting of available phosphorus from soils. The column was fabricated from a plastic syringe fitted at the bottom with a cotton wool and a piece of filter paper to support a soil sample. An aliquot (50 mL) of extracting solution (0.05 M HCl+0.0125 M H(2)SO(4)) was used to extract the sample under gravity flow and the eluate was collected in a polyethylene bottle. The extract was then analyzed for phosphorus contents by a simple flow injection amperometric system, employing a set of three-way solenoid valves as an injection valve. The method is based on the electrochemical reduction of 12-molybdophosphate which is produced on-line by the reaction of orthophosphate with acidic molybdate and the electrical current produced was directly proportional to the concentration of phosphate in range of 0.1-10.0 mg L(-1) PO(4)-P, with a detection limit of 0.02 mg L(-1). Relative standard for 11 replicate injections of 5 mg L(-1) PO(4)-P was 0.5%. A sample through put of 35 h(-1) was achieved, with consumption of 14 mg KCl, 10mg ammonium molybdate and 0.05 mL H(2)SO(4) per analysis. The detection system does not suffer from the interferences that are encountered in the photometric method such as colored substances, colloids, metal ions, silicate and refractive index effect (Schlieren effect). The results obtained by the column extraction procedure were well correlated with those obtained by the steady-state extraction procedure, but showed slightly higher extraction efficiency.

Information or resolution: Which is required from an SEM to study bulk inorganic materials?: Evaluate SEMs’ practical performance

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

Xing, Q.

Significant technological advances in scanning electron microscopy (SEM) have been achieved over the past years. Different SEMs can have significant differences in functionality and performance. This work presents the perspectives on selecting an SEM for research on bulk inorganic materials. Understanding materials demands quantitative composition and orientation information, and informative and interpretable images that reveal subtle differences in chemistry, orientation/structure, topography, and electronic structure. The capability to yield informative and interpretable images with high signal-to-noise ratios and spatial resolutions is an overall result of the SEM system as a whole, from the electron optical column to the detection system. Themore » electron optical column determines probe performance. The roles of the detection system are to capture, filter or discriminate, and convert signal electrons to imaging information. The capability to control practical operating parameters including electron probe size and current, acceleration voltage or landing voltage, working distance, detector selection, and signal filtration is inherently determined by the SEM itself. As a platform for various accessories, e.g. an energydispersive spectrometer and an electron backscatter diffraction detector, the properties of the electron optical column, specimen chamber, and stage greatly affect the performance of accessories. Ease-of-use and ease-of-maintenance are of practical importance. It is practically important to select appropriate test specimens, design suitable imaging conditions, and analyze the specimen chamber geometry and dimensions to assess the overall functionality and performance of an SEM. Finally, for an SEM that is controlled/operated with a computer, the stable software and user-friendly interface significantly affect the usability of the SEM.« less

Separation and characterization of chemical constituents in Ginkgo biloba extract by off-line hydrophilic interaction×reversed-phase two-dimensional liquid chromatography coupled with quadrupole-time of flight mass spectrometry.

PubMed

Ji, Shuai; He, Dan-Dan; Wang, Tian-Yun; Han, Jie; Li, Zheng; Du, Yan; Zou, Jia-Hui; Guo, Meng-Zhe; Tang, Dao-Quan

2017-11-30

Ginkgo biloba extract (GBE), derived from the leaves of Ginkgo biloba L., is one of the most widely used traditional Chinese medicines worldwide. Due to high structural diversity and low abundance of chemical constituents in GBE, conventional reversed-phase liquid chromatography has limited power to meet the needs of its quality control. In this study, an off-line hydrophilic interaction×reversed-phase two-dimensional liquid chromatography (HILIC×RP 2D-LC) system coupled with diode array detection (DAD) and quadrupole time-of-flight mass spectrometry (qTOF-MS) was established to comprehensively analyze the chemical constituents of GBE. After optimizing the chromatographic columns and mobile phase of 2D-LC, a Waters XBridge Amide column using acetonitrile/water/formic acid as the mobile phase was selected as the first dimension to fractionate GBE, and the obtained fractions were further separated on an Agilent Zorbax XDB-C18 column with methanol/water/formic acid as the mobile phase. As a result, a total of 125 compounds were detected in GBE. The orthogonality of the 2D-LC system was 69.5%, and the practical peak capacity was 3864 and 2994, respectively, calculated by two different methods. The structures of 104 compounds were tentatively characterized by qTOF-MS analysis, and 21 of them were further confirmed by comparing with reference standards. This established HILIC×RP 2D-LC-qTOF/MS system can greatly improve the separation and characterization of natural products in GBE or other complicated herbal extracts. Copyright © 2017 Elsevier B.V. All rights reserved.

Constraining the H2 column density distribution at z˜3 from composite DLA spectra

NASA Astrophysics Data System (ADS)

Balashev, S. A.; Noterdaeme, P.

2018-04-01

We present the detection of the average H2 absorption signal in the overall population of neutral gas absorption systems at z ˜ 3 using composite absorption spectra built from the Sloan Digital Sky Survey-III damped Lyman-α catalogue. We present a new technique to directly measure the H2 column density distribution function f_H_2(N) from the average H2 absorption signal. Assuming a power-law column density distribution, we obtain a slope β = -1.29 ± 0.06(stat) ± 0.10 (sys) and an incidence rate of strong H2 absorptions (with N(H2) ≳ 1018 cm-2) to be 4.0 ± 0.5(stat) ± 1.0 (sys) % in H I absorption systems with N(H I)≥1020 cm-2. Assuming the same inflexion point where f_H_2(N) steepens as at z = 0, we estimate that the cosmological density of H2 in the column density range log N(H_2) (cm^{-2})= 18-22 is ˜15% of the total. We find one order of magnitude higher H2 incident rate in a sub-sample of extremely strong DLAs (log N(H I) (cm^{-2}) ≥ 21.7), which, together with the the derived shape of f_H_2(N), suggests that the typical H I-H2 transition column density in DLAs is log N(H)(cm-2) ≳ 22.3 in agreement with theoretical expectations for the average (low) metallicity of DLAs at high-z.

Simultaneous determination of D-aspartic acid and D-glutamic acid in rat tissues and physiological fluids using a multi-loop two-dimensional HPLC procedure.

PubMed

Han, Hai; Miyoshi, Yurika; Ueno, Kyoko; Okamura, Chieko; Tojo, Yosuke; Mita, Masashi; Lindner, Wolfgang; Zaitsu, Kiyoshi; Hamase, Kenji

2011-11-01

For a metabolomics study focusing on the analysis of aspartic and glutamic acid enantiomers, a fully automated two-dimensional HPLC system employing a microbore-ODS column and a narrowbore-enantioselective column was developed. By using this system, a detailed distribution of D-Asp and D-Glu besides L-Asp and L-Glu in mammals was elucidated. For the total analysis concept, the amino acids were first pre-column derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) to be sensitively and fluorometrically detected. For the non-stereoselective separation of the analytes in the first dimension a monolithic ODS column (750 mm × 0.53 mm i.d.) was adopted, and a self-packed narrowbore-Pirkle type enantioselective column (Sumichiral OA-2500S, 250 mm × 1.5 mm i.d.) was selected for the second dimension. In the rat plasma, RSD values for intra-day and inter-day precision were less than 6.8%, and the accuracy ranged between 96.1% and 105.8%. The values of LOQ of D-Asp and D-Glu were 5 fmol/injection (0.625 nmol/g tissue). The present method was successfully applied to the simultaneous determination of free aspartic acid and glutamic acid enantiomers in 7 brain areas, 11 peripheral tissues, plasma and urine of Wistar rats. Biologically significant D-Asp values were found in various tissue samples whereas for D-Glu the values were very low possibly indicating less significance. Copyright © 2011 Elsevier B.V. All rights reserved.

Using the liquid nature of the stationary phase in countercurrent chromatography. IV. The cocurrent CCC method.

PubMed

Berthod, Alain; Hassoun, Mahmoud

2006-05-26

The retention volumes of solutes in countercurrent chromatography (CCC) are directly proportional to their distribution coefficients, K(D) in the biphasic liquid system used as mobile and stationary phase in the CCC column. The cocurrent CCC method consists in putting the liquid "stationary" phase in slow motion in the same direction as the mobile phase. A mixture of five steroid compounds of widely differing polarities was used as a test mixture to evaluate the capabilities of the method with the biphasic liquid system made of water/methanol/ethyl acetate/heptane 6/5/6/5 (v/v) and a 53 mL CCC column of the coil planet centrifuge type. It is shown that the chromatographic resolution obtained in cocurrent CCC is very good because the solute band broadening is minimized as long as the solute is located inside the "stationary" phase. Pushing the method at its limits, it is demonstrated that the five steroids can still be (partly) separated when the flow rate of the two liquid phases is the same (2 mL/min). This is due to the higher volume of upper phase (72% of the column volume) contained inside the CCC column producing a lower linear speed compared to the aqueous lower phase linear speed. The capabilities of the cocurrent CCC method compare well with those of the gradient elution method in HPLC. Continuous detection is a problem due to the fact that two immiscible liquid phases elute from the column. It was partly solved using an evaporative light scattering detector.

Damage Detection of a Concrete Column Subject to Blast Loads Using Embedded Piezoceramic Transducers.

PubMed

Xu, Kai; Deng, Qingshan; Cai, Lujun; Ho, Siuchun; Song, Gangbing

2018-04-28

Some of the most severe structural loadings come in the form of blast loads, which may be caused by severe accidents or even terrorist activities. Most commonly after exposure to explosive forces, a structure will suffer from different degrees of damage, and even progress towards a state of collapse. Therefore, damage detection of a structure subject to explosive loads is of importance. This paper proposes a new approach to damage detection of a concrete column structure subjected to blast loads using embedded piezoceramic smart aggregates (SAs). Since the sensors are embedded in the structure, the proposed active-sensing based approach is more sensitive to internal or through cracks than surface damage. In the active sensing approach, the embedded SAs act as actuators and sensors, that can respectively generate and detect stress waves. If the stress wave propagates across a crack, the energy of the wave attenuates, and the reduction of the energy compared to the healthy baseline is indicative of a damage. With a damage index matrix constructed by signals obtained from an array of SAs, cracks caused by blast loads can be detected throughout the structure. Conventional sensing methods such as the measurement of dynamic strain and acceleration were included in the experiment. Since columns are critical elements needed to prevent structural collapse, knowledge of their integrity and damage conditions is essential for safety after exposure to blast loads. In this research, a concrete column with embedded SAs was chosen as the specimen, and a series of explosive tests were conducted on the column. Experimental results reveal that surface damages, though appear severe, cause minor changes in the damage index, and through cracks result in significant increase of the damage index, demonstrating the effectiveness of the active sensing, enabled by embedded SAs, in damage monitoring of the column under blast loads, and thus providing a reliable indication of structural integrity in the event of blast loads.

Damage Detection of a Concrete Column Subject to Blast Loads Using Embedded Piezoceramic Transducers

PubMed Central

Deng, Qingshan; Cai, Lujun; Ho, Siuchun; Song, Gangbing

2018-01-01

Some of the most severe structural loadings come in the form of blast loads, which may be caused by severe accidents or even terrorist activities. Most commonly after exposure to explosive forces, a structure will suffer from different degrees of damage, and even progress towards a state of collapse. Therefore, damage detection of a structure subject to explosive loads is of importance. This paper proposes a new approach to damage detection of a concrete column structure subjected to blast loads using embedded piezoceramic smart aggregates (SAs). Since the sensors are embedded in the structure, the proposed active-sensing based approach is more sensitive to internal or through cracks than surface damage. In the active sensing approach, the embedded SAs act as actuators and sensors, that can respectively generate and detect stress waves. If the stress wave propagates across a crack, the energy of the wave attenuates, and the reduction of the energy compared to the healthy baseline is indicative of a damage. With a damage index matrix constructed by signals obtained from an array of SAs, cracks caused by blast loads can be detected throughout the structure. Conventional sensing methods such as the measurement of dynamic strain and acceleration were included in the experiment. Since columns are critical elements needed to prevent structural collapse, knowledge of their integrity and damage conditions is essential for safety after exposure to blast loads. In this research, a concrete column with embedded SAs was chosen as the specimen, and a series of explosive tests were conducted on the column. Experimental results reveal that surface damages, though appear severe, cause minor changes in the damage index, and through cracks result in significant increase of the damage index, demonstrating the effectiveness of the active sensing, enabled by embedded SAs, in damage monitoring of the column under blast loads, and thus providing a reliable indication of structural integrity in the event of blast loads. PMID:29710807

Differential subsidence in Mexico City and implications to its Collective Transport System (Metro).

NASA Astrophysics Data System (ADS)

Solano Rojas, D. E.; Wdowinski, S.; Cabral-Cano, E.; Osmanoglu, B.

2017-12-01

Mexico City is one of the fastest subsiding metropolis in the world. At displacement rates ranging from 0 to -380 [mm/yr], the complex geological setting is subjected to differential subsidence, which has led to damage, operation interruptions, and accidents to the Collective Transport System, or Metro. The Metro plays a critical role in Mexico City, carrying more than four million passengers per day. However, no previous study has focused on the deformation monitoring along the 93 km of the Metro surface railways, mainly because of the limitations of the traditional geodetic techniques. In this study, we use high-resolution Interferometric Synthetic Aperture Radar (InSAR) observations to monitor land subsidence throughout the city and quantify differential subsidence along surface Metro lines. Our analysis is based on 34 TerraSAR-X StripMap scenes acquired from May 2011 to June 2013 and 36 COSMO-SkyMed Stripmap scenes acquired from June 2011 to June 2012. The data were processed using the StaMPS InSAR time series technique, obtaining point densities of up to 4827 points/km2. Our post-processing methodologies include the following two components: (1) Detection of differential subsidence along the metro lines by calculating subsidence gradients, and (2) Detection of apparent uplift—areas subsiding slower than their surroundings—by using spatial frequency filtering. The two analyses allow us to recognize four main consequences of differential subsidence in the Metro system: 1. Deflection in elevated railways, 2. Deflection in street-level railways, 3. Columns with decreased loading capacity, and 4. Apparent uplift affecting surrounding infrastructure. Our results aim at shortening the large gap between scientific geodetic studies and applicable engineering parameters that can be used by local authorities in the city for maintenance and new lines development.

Highly sensitive assay for tyrosine hydroxylase activity by high-performance liquid chromatography.

PubMed

Nagatsu, T; Oka, K; Kato, T

1979-07-21

A highly sensitive assay for tyrosine hydroxylase (TH) activity by high-performance liquid chromatography (HPLC) with amperometric detection was devised based on the rapid isolation of enzymatically formed DOPA by a double-column procedure, the columns fitted together sequentially (the top column of Amberlite CG-50 and the bottom column of aluminium oxide). DOPA was adsorbed on the second aluminium oxide column, then eluted with 0.5 M hydrochloric acid, and assayed by HPLC with amperometric detection. D-Tyrosine was used for the control. alpha-Methyldopa was added to the incubation mixture as an internal standard after incubation. This assay was more sensitive than radioassays and 5 pmol of DOPA formed enzymatically could be measured in the presence of saturating concentrations of tyrosine and 6-methyltetrahydropterin. The TH activity in 2 mg of human putamen could be easily measured, and this method was found to be particularly suitable for the assay of TH activity in a small number of nuclei from animal and human brain.

Instant Integrated Ultradeep Quantitative-structural Membrane Proteomics Discovered Post-translational Modification Signatures for Human Cys-loop Receptor Subunit Bias*

PubMed Central

Zhang, Xi

2016-01-01

Neurotransmitter ligand-gated ion channels (LGICs) are widespread and pivotal in brain functions. Unveiling their structure-function mechanisms is crucial to drive drug discovery, and demands robust proteomic quantitation of expression, post-translational modifications (PTMs) and dynamic structures. Yet unbiased digestion of these modified transmembrane proteins—at high efficiency and peptide reproducibility—poses the obstacle. Targeting both enzyme-substrate contacts and PTMs for peptide formation and detection, we devised flow-and-detergent-facilitated protease and de-PTM digestions for deep sequencing (FDD) method that combined omni-compatible detergent, tandem immobilized protease/PNGase columns, and Cys-selective reduction/alkylation, to achieve streamlined ultradeep peptide preparation within minutes not days, at high peptide reproducibility and low abundance-bias. FDD transformed enzyme-protein contacts into equal catalytic travel paths through enzyme-excessive columns regardless of protein abundance, removed products instantly preventing inhibition, tackled intricate structures via sequential multiple micro-digestions along the flow, and precisely controlled peptide formation by flow rate. Peptide-stage reactions reduced steric bias; low contamination deepened MS/MS scan; distinguishing disulfide from M oxidation and avoiding gain/loss artifacts unmasked protein-endogenous oxidation states. Using a recent interactome of 285-kDa human GABA type A receptor, this pilot study validated FDD platform's applicability to deep sequencing (up to 99% coverage), H/D-exchange and TMT-based structural mapping. FDD discovered novel subunit-specific PTM signatures, including unusual nontop-surface N-glycosylations, that may drive subunit biases in human Cys-loop LGIC assembly and pharmacology, by redefining subunit/ligand interfaces and connecting function domains. PMID:27073180

In Situ Monitoring of Dispersion in the Water Column, Final Product for the Detection and Mitigation of Oil within the Water Column Project

DTIC Science & Technology

2018-01-31

properties in the presence of oil, such as conductivity, temperature , and turbidity (Battelle, 2014). The National Response Team (NRT) divides subsea...monitoring of oil and conditions (conductivity, temperature , salinity) in the water column, and discrete sampling and analysis (Battelle, 2014). Sensors

Rapid determination of polycyclic aromatic hydrocarbons in rainwater by liquid-liquid microextraction and LC with core-shell particles column and fluorescence detection.

PubMed

Vinci, Giuliana; Antonelli, Marta L; Preti, Raffaella

2013-02-01

Liquid-liquid microextraction coupled to LC with fluorescence detection for the determination of Environmental Protection Agency's 16 priority pollutant polycyclic aromatic hydrocarbons in rainwater has been developed. The optimization of the extraction method has involved several parameters, including the comparison between an ultrasonic bath and a magnetic stirrer as extractant apparatus, the choice of the extractant solvent, and the optimization of the extraction time. Liquid-liquid microextraction gave good results in terms of recoveries (from 73.6 to 102.8% in rainwater) and repeatability, with a very simple procedure and low solvent consumption. The reported chromatographic method uses a Core-Shell technology column, with particle size <3 μm instead of classical 5-μm particles column. The resulting backpressure was below 300 bar, allowing the use of a conventional HPLC system rather than the more expensive ultrahigh performance LC (UHPLC). An average decrease of 59% in run time and 75% in eluent consumption has been obtained, compared to classical HPLC methods, keeping good separation, sensitivity, and repeatability. The proposed conditions were successfully applied to the determinations of polycyclic aromatic hydrocarbons in genuine rainwater samples. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rapid detection of economic adulterants in fresh milk by liquid chromatography-tandem mass spectrometry.

PubMed

Abernethy, Grant; Higgs, Kerianne

2013-05-03

A method to aid in the detection of the economically driven adulteration of fresh milk with a range of small, nitrogen containing compounds, including melamine, ammeline, ammelide, cyanuric acid, allantoin, thiourea, urea, biuret, triuret, semicarbazide, aminotriazine, 3- and 4-aminotriazole, cyanamide, dicyandiamide, guanidine, choline, hydroxyproline, nitrate, and a range of amino acids, has been developed. (15)N2-Urea is used as an internal standard. The adulteration of milk with exogenous urea has previously been difficult to detect because of the variation in the naturally occurring levels of urea in milk. However, by monitoring the contaminants biuret and triuret, which comprise up to 1% of synthetic urea, the adulteration of milk with urea-based fertilizer can be detected. We estimate that to be economically viable, adulteration of the order of 90-4000ppm of the above adulterants would need to be added to fresh milk. For most of the compounds, an arbitrary detection threshold of 2ppm is therefore more than sufficient. For biuret, a lower detection threshold, better than 0.5ppm, is desirable and the sensitivity for biuret and triuret can be improved by the post-column addition of lithium to create lithium adducts under electrospray ionisation. Sample handling involves a two-step solvent precipitation method that is deployed in a 96-well plate format, and the hydrophilic interaction liquid chromatography uses a rapid gradient (1.2min). Three separate injections, to detect the positively charged compounds, the negatively charged compounds and amino acids and finally the lithium adducts, are used. This rapid and qualitative survey method may be deployed as a second tier screening method to quickly reduce sample numbers indicated as irregular by an FTIR based screening system, and to direct analysis to appropriate quantification methods. Copyright © 2013 Elsevier B.V. All rights reserved.

Application of a simple column-switching ion chromatography technique for removal of matrix interferences and sensitive fluorescence determination of acidic compounds (pharmaceutical drugs) in complex samples.

PubMed

Muhammad, Nadeem; Subhani, Qamar; Wang, Fenglian; Guo, Dandan; Zhao, Qiming; Wu, Shuchao; Zhu, Yan

2017-09-15

This work illustrates the introduction of a simple, rugged and flexible column-switching ion chromatography (IC) technique for an automated on-line QuEChERS extracted samples extracts washing followed by sensitive fluorescence (FLD) determination of five acidic pharmaceutical drugs namely; clofibric acid (CLO), ibuprofen (IBU), aspirin (ASP), naproxen (NAP) and flurobrofen (FLU) in three complex samples (spinach, apple and hospital sewage sludge). An old anion exchange column IonPac ® AS11-HC was utilized as a pre-treatment column for on-line washing of inorganic and organic interferences followed by isocratic separation of five acidic drugs with another anion exchange IonPac ® AS12A analytical column by exploiting the column-switching technique. This novel method exhibited good linearity with correlation coefficients (r 2 ) for all drugs were in the range 0.976-0.996. The limit of detection and quantification of all five acidic drugs were in the range 0.024μg/kg to 8.70μg/kg and 0.082μg/kg to 0.029mg/kg, respectively, and better recoveries in the range 81.17-112.5% with percentage relative standard deviations (RSDs) less than 17.8% were obtained. This on-line sample pre-treatment method showed minimum matrix effect in the range of 0.87-1.25 except for aspirin. This simple rugged and flexible column-switching system required only 28min for maximum elimination of matrices and interferences in three complex samples extracts, isocratic separation of five acidic drugs and for the continuous regeneration of pre-treatment column prior to every subsequent analysis. Finally, this simple automated IC system was appeared so rugged and flexible, which can eliminate and wash out most of interference, impurities and matrices in complex samples, simply by adjusting the NaOH and acetonitrile concentration in washing mobile phase with maximum recoveries of acidic analytes of interest. Copyright © 2017. Published by Elsevier B.V.

Rapid regulation of brain-derived neurotrophic factor mRNA within eye-specific circuits during ocular dominance column formation.

PubMed

Lein, E S; Shatz, C J

2000-02-15

The neurotrophin brain-derived neurotrophic factor (BDNF) has emerged as a candidate retrograde signaling molecule for geniculocortical axons during the formation of ocular dominance columns. Here we examined whether neuronal activity can regulate BDNF mRNA in eye-specific circuits in the developing cat visual system. Dark-rearing throughout the critical period for ocular dominance column formation decreases levels of BDNF mRNA within primary visual cortex, whereas short-term (2 d) binocular blockade of retinal activity with tetrodotoxin (TTX) downregulates BDNF mRNA within the lateral geniculate nucleus (LGN) and visual cortical areas. Brief (6 hr to 2 d) monocular TTX blockade during the critical period and also in adulthood causes downregulation in appropriate eye-specific laminae in the LGN and ocular dominance columns within primary visual cortex. Monocular TTX blockade at postnatal day 23 also downregulates BDNF mRNA in a periodic fashion, consistent with recent observations that ocular dominance columns can be detected at these early ages by physiological methods. In contrast, 10 d monocular TTX during the critical period does not cause a lasting decrease in BDNF mRNA expression in columns pertaining to the treated eye, consistent with the nearly complete shift in physiological response properties of cortical neurons in favor of the unmanipulated eye known to result from long-term monocular deprivation. These observations demonstrate that BDNF mRNA levels can provide an accurate "molecular readout" of the activity levels of cortical neurons and are consistent with a highly local action of BDNF in strengthening and maintaining active synapses during ocular dominance column formation.

[Rapid determination of trace iodate using monolithic column ion-pair chromatography coupled with direct conductivity detection].

PubMed

Liu, Yuzhen; Yu, Hong; Li, Siwen

2011-10-01

A method was developed on a monolithic column for the fast determination of trace iodate (IO(3)- ) by ion-pair chromatography with direct conductivity detection. The analytes were separated using a mobile phase of tetrabutylammonium hydroxide (TBA)-phthalic acid-acetonitrile on a reversed-phase silica-based monolithic column. The effects of eluent, flow rate and column temperature on the retention of iodate were investigated. The optimized chromatographic conditions for the determination of the anion were as follows: 0. 25 mmol/L TBA-0. 18 mmol/L phthalic acid-3% acetonitrile (pH 5.5) as mobile phase, a flow rate of 4.0 mL/min and a column temperature of 30 degrees C. Under the optimal conditions, retention time of iodate was less than 0. 5 min and the baseline separation of iodate was achieved without any interference by other anions (Cl-, NO , SO4(2)-, I- ). The detection limit (S/N= 3) was 0.36 mg/L for IO(3)- . Relative standard deviation (RSD, n = 5) of chromatographic peak area and retention time were 0. 35% and 0. 28%, respectively. The proposed method was applied to the determination of trace iodate in iodized medicine. The spiked recovery of iodate was 96. 4%. The method is rapid, simple, accurate, reliable, and practical.

Determination of phenolic acids and flavonoids in Taraxacum formosanum Kitam by liquid chromatography-tandem mass spectrometry coupled with a post-column derivatization technique.

PubMed

Chen, Hung-Ju; Inbaraj, Baskaran Stephen; Chen, Bing-Huei

2012-01-01

A liquid chromatography-tandem mass spectrometry method (LC-MS/MS) was developed for the determination of phenolic acids and flavonoids in a medicinal Chinese herb Taraxacum formosanum Kitam. Initially, both phenolic acids and flavonoids were extracted with 50% ethanol in a water-bath at 60 °C for 3 h and eventually separated into acidic fraction and neutral fraction by using a C(18) cartridge. A total of 29 compounds were separated within 68 min by employing a Gemini C(18) column and a gradient solvent system of 0.1% formic acid and acetonitrile at a flow rate of 1.0 mL/min. Based on the retention behavior as well as absorption and mass spectra, 19 phenolic acids and 10 flavonoids were identified and quantified in T. formosanum, with the former ranging from 14.1 μg/g to 10,870.4 μg/g, and the latter from 9.9 μg/g to 325.8 μg/g. For further identification of flavonoids, a post-column derivatization method involving shift reagents such as sodium acetate or aluminum chloride was used and the absorption spectral characteristics without or with shift reagents were compared. An internal standard syringic acid was used for quantitation of phenolic acids, whereas (±) naringenin was found suitable for quantitation of flavonoids. The developed LC-MS/MS method showed high reproducibility, as evident from the relative standard deviation (RSD) values for intra-day and inter-day variability being 1.0-6.8% and 2.0-7.7% for phenolic acids and 3.7-7.4% and 1.5-8.1% for flavonoids, respectively, and thus may be applied for simultaneous determination of phenolic acids and flavonoids in Chinese herb and nutraceuticals.

Neutron camera employing row and column summations

DOEpatents

Clonts, Lloyd G.; Diawara, Yacouba; Donahue, Jr, Cornelius; Montcalm, Christopher A.; Riedel, Richard A.; Visscher, Theodore

2016-06-14

For each photomultiplier tube in an Anger camera, an R.times.S array of preamplifiers is provided to detect electrons generated within the photomultiplier tube. The outputs of the preamplifiers are digitized to measure the magnitude of the signals from each preamplifier. For each photomultiplier tube, a corresponding summation circuitry including R row summation circuits and S column summation circuits numerically add the magnitudes of the signals from preamplifiers for each row and for each column to generate histograms. For a P.times.Q array of photomultiplier tubes, P.times.Q summation circuitries generate P.times.Q row histograms including R entries and P.times.Q column histograms including S entries. The total set of histograms include P.times.Q.times.(R+S) entries, which can be analyzed by a position calculation circuit to determine the locations of events (detection of a neutron).

VizieR Online Data Catalog: Gamma Ray Bursts detected by Swift (2004-2015) (Buchner+, 2017)

NASA Astrophysics Data System (ADS)

Buchner, J.; Schulze, S.; Bauer, F.

2016-04-01

Gamma Ray Bursts (GRB) typically show intrinsic LOS column densities of 1021-23cm2. We performed a thorough statistical analysis of all available X-ray spectra of Swift-detected GRBs. In the associated paper we use sub-samples to analyse the population properties of LGRB and concluded that the obscuration is due to large-scale gas inside the GRB host galaxy, due to the shape of the column density distribution and its correlation with host stellar mass. This catalogue presents X-ray spectral analysis of all Swift-detected GRBs. It includes information about the GRB (ID, Swift Trigger ID, duration, RA/Dec in J2000, galactic coordinates, Milky Way column density). Those properties are taken from the http://www.swift.ac.uk/ and http://gcn.gsfc.nasa.gov/ websites. We removed prompt emission and flares, leaving only a certain time interval for spectral extraction. We use two models to analyse X-ray spectra: TBABS and SPHERE. Both include updated abundances and cross-sections as compared to previous works. The latter includes the effects of Compton-scattering and FeKa fluorescence relevant at high column densities. Columns list the posterior mean, standard deviation, 10% and 90% quantiles. Note that the column densities are converted to hydrogen assuming local ISM abundances, but are derived primarily from photo-electric absorption of e.g. Fe and O, and therefore primarily measure metal gas. (2 data files).

Column-coupling strategies for multidimensional electrophoretic separation techniques.

PubMed

Kler, Pablo A; Sydes, Daniel; Huhn, Carolin

2015-01-01

Multidimensional electrophoretic separations represent one of the most common strategies for dealing with the analysis of complex samples. In recent years we have been witnessing the explosive growth of separation techniques for the analysis of complex samples in applications ranging from life sciences to industry. In this sense, electrophoretic separations offer several strategic advantages such as excellent separation efficiency, different methods with a broad range of separation mechanisms, and low liquid consumption generating less waste effluents and lower costs per analysis, among others. Despite their impressive separation efficiency, multidimensional electrophoretic separations present some drawbacks that have delayed their extensive use: the volumes of the columns, and consequently of the injected sample, are significantly smaller compared to other analytical techniques, thus the coupling interfaces between two separations components must be very efficient in terms of providing geometrical precision with low dead volume. Likewise, very sensitive detection systems are required. Additionally, in electrophoretic separation techniques, the surface properties of the columns play a fundamental role for electroosmosis as well as the unwanted adsorption of proteins or other complex biomolecules. In this sense the requirements for an efficient coupling for electrophoretic separation techniques involve several aspects related to microfluidics and physicochemical interactions of the electrolyte solutions and the solid capillary walls. It is interesting to see how these multidimensional electrophoretic separation techniques have been used jointly with different detection techniques, for intermediate detection as well as for final identification and quantification, particularly important in the case of mass spectrometry. In this work we present a critical review about the different strategies for coupling two or more electrophoretic separation techniques and the different intermediate and final detection methods implemented for such separations.

Investigations on mobility of carbon colloid supported nanoscale zero-valent iron (nZVI) in a column experiment and a laboratory 2D-aquifer test system.

PubMed

Busch, Jan; Meißner, Tobias; Potthoff, Annegret; Oswald, Sascha E

2014-09-01

Nanoscale zero-valent iron (nZVI) has recently gained great interest in the scientific community as in situ reagent for installation of permeable reactive barriers in aquifer systems, since nZVI is highly reactive with chlorinated compounds and may render them to harmless substances. However, nZVI has a high tendency to agglomerate and sediment; therefore it shows very limited transport ranges. One new approach to overcome the limited transport of nZVI in porous media is using a suited carrier colloid. In this study we tested mobility of a carbon colloid supported nZVI particle "Carbo-Iron Colloids" (CIC) with a mean size of 0.63 μm in a column experiment of 40 cm length and an experiment in a two-dimensional (2D) aquifer test system with dimensions of 110 × 40 × 5 cm. Results show a breakthrough maximum of 82 % of the input concentration in the column experiment and 58 % in the 2D-aquifer test system. Detected residuals in porous media suggest a strong particle deposition in the first centimeters and few depositions in the porous media in the further travel path. Overall, this suggests a high mobility in porous media which might be a significant enhancement compared to bare or polyanionic stabilized nZVI.

Optimal Artificial Boundary Condition Configurations for Sensitivity-Based Model Updating and Damage Detection

DTIC Science & Technology

2010-09-01

matrix is used in many methods, like Jacobi or Gauss Seidel , for solving linear systems. Also, no partial pivoting is necessary for a strictly column...problems that arise during the procedure, which in general, converges to the solving of a linear system. The most common issue with the solution is the... iterative procedure to find an appropriate subset of parameters that produce an optimal solution commonly known as forward selection. Then, the

P39-T Analysis of Oligosaccharides by Capillary-Scale High-Performance Anion-Exchange Chromatography with Pulsed Amperometric Detection (CHPAEC-PAD) and On-Line Electrospray-Ionization Ion-Trap Mass Spectrometry (CHPAEC-ITMS)

PubMed Central

Bruggink, C.; Koeleman, C.; Barreto, V.; Lui, Y.; Pohl, C.; Ingendoh, A.; Wuhrer, M.; Hokke, C.; Deelder, A.

2007-01-01

High-pH anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) is an established technique for selective separation and analysis of underivatized carbohydrates. The miniaturization of chromatographic techniques by means of capillary columns, and on-line coupling to mass spectrometry are critical to the further development of glycan analysis methods that are compatible with the current requirements in clinical settings. A system has been developed based on the Dionex BioLC equipped with a microbore gradient pump with PEEK flow splitter, a FAMOS micro autosampler, a modified electrochemical cell for on-line capillary PAD, and a capillary column (380 μm i.d.) packed with a new type of anion-exchange resin. This system operates with sensitivity in the low femtomol range. In addition, an on-line capillary desalter has been developed to allow direct coupling to the Bruker Esquire 3000 ion-trap mass spectrometer with electrospray ionization interface (ESI-IT-MS). Both systems have been evaluated using oligosaccharide standards as well as urine samples exhibiting various lysosomal oligosaccharide storage diseases. Initial data indicate that the robust and selective anion-exchange system, in combination with ESI-IT-MS for structure confirmation and analysis, provides a powerful platform that complements existing nano/capillary LC-MS methods for analytical determination of oligosaccharides in biological matrices.

Electronic drive and acquisition system for mass spectrometry

NASA Technical Reports Server (NTRS)

Schaefer, Rembrandt Thomas (Inventor); Chutjian, Ara (Inventor); Tran, Tuan (Inventor); Madzunkov, Stojan M. (Inventor); Thomas, John L. (Inventor); Mojarradi, Mohammad (Inventor); MacAskill, John (Inventor); Blaes, Brent R. (Inventor); Darrach, Murray R. (Inventor); Burke, Gary R. (Inventor)

2010-01-01

The present invention discloses a mixed signal RF drive electronics board that offers small, low power, reliable, and customizable method for driving and generating mass spectra from a mass spectrometer, and for control of other functions such as electron ionizer, ion focusing, single-ion detection, multi-channel data accumulation and, if desired, front-end interfaces such as pumps, valves, heaters, and columns.

Detection, manipulation and post processing of circulating tumor cells using optical techniques

NASA Astrophysics Data System (ADS)

Bakhtiaridoost, Somayyeh; Habibiyan, Hamidreza; Ghafoorifard, Hassan

2015-12-01

Circulating tumor cells (CTCs) are malignant cells that are derived from a solid tumor in the metastasis stage and are shed into the blood stream. These cells hold great promise to be used as liquid biopsy that is less aggressive than traditional biopsy. Recently, detection and enumeration of these cells has received ever-increasing attention from researchers as a way of early detection of cancer metastasis, determining the effectiveness of treatment and studying the mechanism of formation of secondary tumors. CTCs are found in blood at low concentration, which is a major limitation of isolation and detection of these cells. Over the last few years, multifarious research studies have been conducted on accurate isolation and detection and post processing of CTCs. Among all the proposed systems, microfluidic systems seem to be more attractive for researchers due to their numerous advantages. On the other hand, recent developments in optical methods have made the possibility of cellular studies at single-cell level. Thus, accuracy and efficiency of separation, detection and manipulation of CTCs can be improved using optical techniques. In this review, we describe optical methods that have been used for CTC detection, manipulation and post processing.

Automated metal-free multiple-column nanoLC for improved phosphopeptide analysis sensitivity and throughput

PubMed Central

Zhao, Rui; Ding, Shi-Jian; Shen, Yufeng; Camp, David G.; Livesay, Eric A.; Udseth, Harold; Smith, Richard D.

2009-01-01

We report on the development and characterization of automated metal-free multiple-column nanoLC instrumentation for sensitive and high-throughput analysis of phosphopeptides with mass spectrometry analysis. The system implements a multiple-column capillary LC fluidic design developed for high-throughput analysis of peptides (Anal. Chem. 2001, 73, 3011–3021), incorporating modifications to achieve broad and sensitive analysis of phosphopeptides. The integrated nanoLC columns (50 µm i.d. × 30 cm containing 5 µm C18 particles) and the on-line solid phase extraction columns (150 µm i.d. × 4 cm containing 5 µm C18 particles) were connected to automatic switching valves with non-metal chromatographic accessories, and other modifications to avoid the exposure of the analyte to any metal surfaces during handling, separation, and electrospray ionization. The nanoLC developed provided a separation peak capacity of ∼250 for phosphopeptides (and ∼400 for normal peptides). A detection limit of 0.4 fmol was obtained when a linear ion trap tandem mass spectrometer (Finnegan LTQ) was coupled to a 50-µm i.d. column of the nanoLC. The separation power and sensitivity provided by the nanoLC-LTQ enabled identification of ∼4600 phosphopeptide candidates from ∼60 µg COS-7 cell tryptic digest followed by IMAC enrichment and ∼520 tyrosine phosphopeptides from ∼2 mg of human T cells digests followed by phosphotyrosine peptide immunoprecipitation. PMID:19217835

Model study of enhanced oil recovery by flooding with aqueous surfactant solution and comparison with theory.

PubMed

Fletcher, Paul D I; Savory, Luke D; Woods, Freya; Clarke, Andrew; Howe, Andrew M

2015-03-17

With the aim of elucidating the details of enhanced oil recovery by surfactant solution flooding, we have determined the detailed behavior of model systems consisting of a packed column of calcium carbonate particles as the porous rock, n-decane as the trapped oil, and aqueous solutions of the anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT). The AOT concentration was varied from zero to above the critical aggregation concentration (cac). The salt content of the aqueous solutions was varied to give systems of widely different, post-cac oil-water interfacial tensions. The systems were characterized in detail by measuring the permeability behavior of the packed columns, the adsorption isotherms of AOT from the water to the oil-water interface and to the water-calcium carbonate interface, and oil-water-calcium carbonate contact angles. Measurements of the percent oil recovery by pumping surfactant solutions into calcium carbonate-packed columns initially filled with oil were analyzed in terms of the characterization results. We show that the measured contact angles as a function of AOT concentration are in reasonable agreement with those calculated from values of the surface energy of the calcium carbonate-air surface plus the measured adsorption isotherms. Surfactant adsorption onto the calcium carbonate-water interface causes depletion of its aqueous-phase concentration, and we derive equations which enable the concentration of nonadsorbed surfactant within the packed column to be estimated from measured parameters. The percent oil recovery as a function of the surfactant concentration is determined solely by the oil-water-calcium carbonate contact angle for nonadsorbed surfactant concentrations less than the cac. For surfactant concentrations greater than the cac, additional oil removal occurs by a combination of solubilization and emulsification plus oil mobilization due to the low oil-water interfacial tension and a pumping pressure increase.

Parallel computation of level set method for 500 Hz visual servo control

NASA Astrophysics Data System (ADS)

Fei, Xianfeng; Igarashi, Yasunobu; Hashimoto, Koichi

2008-11-01

We propose a 2D microorganism tracking system using a parallel level set method and a column parallel vision system (CPV). This system keeps a single microorganism in the middle of the visual field under a microscope by visual servoing an automated stage. We propose a new energy function for the level set method. This function constrains an amount of light intensity inside the detected object contour to control the number of the detected objects. This algorithm is implemented in CPV system and computational time for each frame is 2 [ms], approximately. A tracking experiment for about 25 s is demonstrated. Also we demonstrate a single paramecium can be kept tracking even if other paramecia appear in the visual field and contact with the tracked paramecium.

Fabry-Perot Interferometer for Column CO2

NASA Technical Reports Server (NTRS)

Heaps, William S.; Kawa, Randolph; Bhartia, P. K. (Technical Monitor)

2002-01-01

Global atmospheric CO2 measurements are essential to resolving significant discrepancies in our understanding of the global carbon budget and, hence, humankind's role in global climate change. The science measurement requirements for CO2 are extremely demanding (precision approx. 0.3%). No atmospheric chemical species has ever been measured from space with this precision. We are developing a novel application of a Fabry-Perot interferometer to detect spectral absorption of reflected sunlight by CO2 and O2 in the atmosphere. Preliminary design studies indicate that the method will be able to achieve the sensitivity and signal-to-noise detection required to measure column CO2 at the target specification. The objective of this program is to construct a prototype instrument for deployment on an aircraft to test the instrument performance and our ability to retrieve the data in the real atmosphere. To date we have assembled a laboratory bench system to begin testing the optical and electronic components. We are also measuring signal and noise levels in actual sunlight to evaluate component performance.

[Study on HPLC fingerprint of 11 Taraxacum species in northeast of China].

PubMed

Zhu, Dan; Zhao, Xin; Xu, Qiao; Ning, Wei

2011-04-01

To study the RP-HPLC fingerprints of 11 plants in the genus Taraxacum for their quality control. The fingerprints were determined using an Agilent 1100 series instrument system. Chromatographic analyses were performed on a Kromasil 100-5 C18 (4.6 mm x 250 mm, 5 microm) analytical column,eluted with methanol and water containing 0.5% acetic acid as the mobile phases in gradient elution at the flow rate of 1.0 mL x min(-1). The detection wavelength was 323 nm. The temperature of column was 35 degrees C. Eleven species of Taraxacum in northeast of China were detected respectively. Twenty-five common peaks existed in 11 RP-HPLC fingerprints. By comparing the retention time and the on-line UV spectra, peaks No. 10, No. 12, No. 16 and No. 25 were identified as chlorogenic acid, caffeic acid, p-coumaroy acid and luteolin respectively. The analytical method with good precision and reproducibility can be useful in the quality control of Taraxacum plants.

Effects of expected-value information and display format on recognition of aircraft subsystem abnormalities

NASA Technical Reports Server (NTRS)

Palmer, Michael T.; Abbott, Kathy H.

1994-01-01

This study identifies improved methods to present system parameter information for detecting abnormal conditions and to identify system status. Two workstation experiments were conducted. The first experiment determined if including expected-value-range information in traditional parameter display formats affected subject performance. The second experiment determined if using a nontraditional parameter display format, which presented relative deviation from expected value, was better than traditional formats with expected-value ranges included. The inclusion of expected-value-range information onto traditional parameter formats was found to have essentially no effect. However, subjective results indicated support for including this information. The nontraditional column deviation parameter display format resulted in significantly fewer errors compared with traditional formats with expected-value-ranges included. In addition, error rates for the column deviation parameter display format remained stable as the scenario complexity increased, whereas error rates for the traditional parameter display formats with expected-value ranges increased. Subjective results also indicated that the subjects preferred this new format and thought that their performance was better with it. The column deviation parameter display format is recommended for display applications that require rapid recognition of out-of-tolerance conditions, especially for a large number of parameters.

Bioactive amines in sorghum: method optimisation and influence of line, tannin and hydric stress.

PubMed

Paiva, Caroline Liboreiro; Evangelista, Warlley Pinheiro; Queiroz, Valéria Aparecida Vieira; Glória, Maria Beatriz Abreu

2015-04-15

The profile and levels of bioactive amines in different sorghum lines were reported for the first time. The amines were quantified by ion-pair HPLC, post-column derivatisation with o-phthalaldehyde and fluorimetric detection. The extraction procedure was optimised: 420 μm particle size, extraction with 5% trichloroacetic acid and three extractions. The screening of 22 sorghum lines showed that four of the ten amines investigated were detected. Spermine and spermidine were the prevalent amines (100%), followed by putrescine (77%) and cadaverine (14%). Total amines ranged from 5.8 to 41.4 mg/100 g, and the polyamines represented 60-100% of the total. Sorghum without tannin had higher amines levels compared to sorghum with tannin and cadaverine was specific to samples without tannin. Hydric stress caused accumulation of spermidine in the grains and affected the levels of other amines at rates depending on the presence or not of tannin. Sorghum is a significant source of polyamines. Copyright © 2014 Elsevier Ltd. All rights reserved.

Water-quality assessment of the Rio Grande Valley, Colorado, New Mexico, and Texas; occurrence and distribution of selected pesticides and nutrients at selected surface-water sites in the Mesilla Valley, 1994-95

USGS Publications Warehouse

Healy, D.F.

1996-01-01

The Rio Grande Valley study unit of the U.S. Geological Survey National Water-Quality Assessment Program conducted a two-phase synoptic study of the occurrence and distribution of pesticides and nutrients in the surface water of the Mesilla Valley, New Mexico and Texas. Phase one, conducted in April-May 1994 during the high-flow irrigation season, consisted of a 6-week time- series sampling event during which 17 water-column samples were collected at 3 main-stem sites on the Rio Grande and a synoptic irrigation-run sampling event during which 19 water-column samples were collected at 7 main-stem sites, 10 drain sites, and 2 sites at the discharges of wastewater-treatment plants. Three samples are included in both the time-series and irrigation-run events. Phase two, conducted in January 1995 during the low-flow non-irrigation season, consisted of a non-irrigation synoptic sampling event during which 18 water-column samples were collected at seven main-stem sites, nine drain sites, and two sites at the discharges of wastewater-treatment plants and a bed- material sampling event during which 6 bed-material samples were collected at six sites near the mouths of drains that discharge to the Rio Grande. The 51 water-column samples were analyzed for 78 pesticides and metabolites and 8 nutrients along with other constituents. The six bed-material samples were analyzed for 21 pesticides and metabolites, gross polychlorinated biphenyls, and gross polychlorinated naphthalenes. The presence of dissolved pesticides in the surface water of the Mesilla Valley is erratic. A total of 100 detections of 17 different pesticides were detected in 44 of the water-column samples. As many as 38 percent of these detections may be attributed to pesticide use upstream from the valley or to nonagricultural pesticide use within the valley. There were 29 detections of 10 different pesticides in 17 samples during the irrigation run and 41 detections of 13 pesticides in 16 samples during the non-irrigation run. Nine pesticides were detected during both phases of the study. The most commonly detected pesticides in the water-column samples were DCPA, which was detected in 29 samples, and metolachlor, which was detected in 17 of the samples. DCPA was detected throughout the Mesilla Valley, whereas metolachlor was detected mainly in the northern and central parts of the valley. The maximum pesticide concentration found during the study was 0.75 microgram per liter of carbofuran, which was detected at the East Side Drain site during the irrigation run. No water-column pesticide concentration exceeded U.S. Environmental Protection Agency's drinking-water standards or any applicable Federal or State criteria or guidelines. A total of 21 occurrences of six pesticides and metabolites were found in the bed-material samples. Chlordane, diazinon, and methyl parathion were detected once each, whereas DDD, DDE, and DDT were detected at all six bed-material sites. Water-column samples for the analysis of nutrient concentrations were collected at all sampling sites during both phases of the study. The concentrations of each nutrient ranged from at or below the individual minimum reporting level to as much as two or three orders of magnitude larger than the minimum reporting level. The concentration of each nutrient was left skewed with most of the values toward the lower end of the range. The larger concentrations of each nutrient, except dissolved nitrite plus nitrate, were associated with wastewater-treatment- plant sites 4 and 16. The larger concentrations of dissolved nitrite plus nitrate were generally associated with the non- irrigation run; however, the largest concentration was at site 4 during the irrigation run. During this study, the Mesilla Valley as a unit was a source of nutrients to the Rio Grande. Wi

Comparison of UHPLC and HPLC in benzodiazepines analysis of postmortem samples: a case-control study.

PubMed

Behnoush, Behnam; Sheikhazadi, Ardeshir; Bazmi, Elham; Fattahi, Akbar; Sheikhazadi, Elham; Saberi Anary, Seyed Hossein

2015-04-01

The aim of this study was to compare system efficiency and analysis duration regarding the solvent consumption and system maintenance in high-pressure liquid chromatography (HPLC) and ultra high-pressure liquid chromatography (UHPLC). In a case-control study, standard solutions of 7 benzodiazepines (BZs) and 73 biological samples such as urine, tissue, stomach content, and bile that screened positive for BZs were analyzed by HPLC and UHPLC in laboratory of forensic toxicology during 2012 to 2013. HPLC analysis was performed using a Knauer by 100-5 C-18 column (250 mm × 4.6 mm) and Knauer photodiode array detector (PAD). UHPLC analysis was performed using Knauer PAD detector with cooling autosampler and Eurospher II 100-3 C-18 column (100 mm × 3 mm) and also 2 pumps. The mean retention time, standard deviation, flow rate, and repeatability of analytical results were compared by using 2 methods. Routine runtimes in HPLC and UHPLC took 40 and 15 minutes, respectively. Changes in mobile phase composition of the 2 methods were not required. Flow rate and solvent consumption in UHPLC decreased. Diazepam and flurazepam were detected more frequently in biological samples. In UHPLC, small particle size and short length of column cause effective separation of BZs in a very short time. Reduced flow rate, solvent consumption, and injection volume cause more efficiency and less analysis costs. Thus, in the detection of BZs, UHPLC is an accurate, sensitive, and fast method with less cost of analysis.

Comparison of UHPLC and HPLC in Benzodiazepines Analysis of Postmortem Samples

PubMed Central

Behnoush, Behnam; Sheikhazadi, Ardeshir; Bazmi, Elham; Fattahi, Akbar; Sheikhazadi, Elham; Saberi Anary, Seyed Hossein

2015-01-01

Abstract The aim of this study was to compare system efficiency and analysis duration regarding the solvent consumption and system maintenance in high-pressure liquid chromatography (HPLC) and ultra high-pressure liquid chromatography (UHPLC). In a case–control study, standard solutions of 7 benzodiazepines (BZs) and 73 biological samples such as urine, tissue, stomach content, and bile that screened positive for BZs were analyzed by HPLC and UHPLC in laboratory of forensic toxicology during 2012 to 2013. HPLC analysis was performed using a Knauer by 100-5 C-18 column (250 mm × 4.6 mm) and Knauer photodiode array detector (PAD). UHPLC analysis was performed using Knauer PAD detector with cooling autosampler and Eurospher II 100-3 C-18 column (100 mm × 3 mm) and also 2 pumps. The mean retention time, standard deviation, flow rate, and repeatability of analytical results were compared by using 2 methods. Routine runtimes in HPLC and UHPLC took 40 and 15 minutes, respectively. Changes in mobile phase composition of the 2 methods were not required. Flow rate and solvent consumption in UHPLC decreased. Diazepam and flurazepam were detected more frequently in biological samples. In UHPLC, small particle size and short length of column cause effective separation of BZs in a very short time. Reduced flow rate, solvent consumption, and injection volume cause more efficiency and less analysis costs. Thus, in the detection of BZs, UHPLC is an accurate, sensitive, and fast method with less cost of analysis. PMID:25860209

Determination of josamycin residues in porcine tissues using high-performance liquid chromatography with pre-column derivatization and spectrofluorimetric detection.

PubMed

Leroy, P; Decolin, D; Nicolas, A; Archimbault, P

1994-12-01

A simple, selective and sensitive high-performance liquid chromatographic (HPLC) method has been developed for the measurement of josamycin residues in four porcine tissues (i.e., muscle, liver, kidney and fat). The sample preparation consisted of a homogenization step in an acetonitrile-10 mmol l-1 phosphate buffer mixture, pH 6.0 (35 + 65), centrifugation and a liquid-liquid extractive clean-up of the resulting supernatant with isooctane. Pre-column derivatization of josamycin was performed using cyclohexa-1,3-dione in ammonium acetate buffer, pH 5.0 (90 degrees C for 2 h). The derivative was chromatographed in an isocratic reversed-phase HPLC system. A LiChrospher RP 18 end-capped (5 microns) column was eluted with an acetonitrile-methanol-10 mmol l-1 phosphate buffer mixture, pH 6.0 (45 + 5 + 50). The capacity factor of the josamycin derivative was 17.5. Detection was achieved using spectrofluorimetry (lambda ex = 375 nm; lambda em = 450 nm). The structure of the derivative was assessed by using mass spectrometry. Full selectivity was obtained in the HPLC system versus other macrolide antibiotics (tylosin, spiramycin and erythromycin), aldehydes (formaldehyde, acetaldehyde and benzaldehyde) and endogenous compounds. Linearity and repeatability were tested. Correlation coefficients, for calibration curves in the range of 0.1-3.2 micrograms g-1, were greater than 0.999 for all tissues and the relative standard deviation (S(r)) was 4.9% (1.6 micrograms g-1; n = 6); recovery was higher than 88%.

Distributed cable sensors with memory feature for post-disaster damage assessment

NASA Astrophysics Data System (ADS)

Chen, Genda; McDaniel, Ryan D.; Pommerenke, David J.; Sun, Shishuang

2005-05-01

A new design of distributed crack sensors is presented for the condition assessment of reinforced concrete (RC) structures during and immediately after an earthquake event. This study is mainly focused on the performance of cable sensors under dynamic loading, particularly their ability to memorize the crack history of an RC member. This unique memory feature enables the post-earthquake condition assessment of structural members such as RC columns, in which the earthquake-induced cracks are closed immediately after an earthquake event due to gravity loads and they are visually undetectable. Factors affecting the onset of the memory feature were investigated experimentally with small-scale RC beams under cyclic loading. Test results indicated that both crack width and the number of loading cycles were instrumental in the onset of the memory feature of cable sensors. Practical issues related to dynamic acquisition with the sensors were discussed. The sensors were proven to be fatigue resistant from the shake table tests of RC columns. They continued to show useful signal after the columns can no longer support additional loads.

A Simplified Method for Sampling and Analysis of High Volume Surface Water for Organic Contaminants Using XAD-2

USGS Publications Warehouse

Datta, S.; Do, L.V.; Young, T.M.

2004-01-01

A simple compressed-gas driven system for field processing and extracting water for subsequent analyses of hydrophobic organic compounds is presented. The pumping device is a pneumatically driven pump and filtration system that can easily clarify at 4L/min. The extraction device uses compressed gas to drive filtered water through two parallel XAD-2 resin columns, at about 200 mL/min. No batteries or inverters are required for water collection or processing. Solvent extractions were performed directly in the XAD-2 glass columns. Final extracts are cleaned-up on Florisil cartridges without fractionation and contaminants analyzed by GC-MS. Method detection limits (MDLs) and recoveries for dissolved organic contaminants, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and pesticides are reported along with results of surface water analysis for the San Francisco Bay, CA.

Fabrication and investigation of electrochromatographic columns with a simplex configuration.

PubMed

Liu, Qing; Yang, Lijun; Wang, Qiuquan; Zhang, Bo

2014-07-04

Duplex capillary columns with a packed and an open section are widely used in electrochromatography (CEC). The duplex column configuration leads to non-uniform voltage drop, electrical field distribution and separation performance. It also adds to the complexity in understanding and optimizing electrochromatographic process. In this study, we introduced a simplex column configuration based on single particle fritting technology. The new column configuration has an essentially uniform packed bed through the entire column length, with only 1mm length left unpacked serving as the optical detection window. The study shows that a simplex column has higher separation efficiency than a duplex column, especially at the high voltage range, due to the consistent distribution of electrical field over the column length. In comparison to the duplex column, the simplex column presented a lower flow rate at the same applied voltage, suggesting that an open section may support a higher speed than a packed section. In practice, the long and short ends of the simplex column could be used as independent CEC columns respectively. This "two-in-one" bi-functional column configuration provided extra flexibilities in selecting and optimizing electrochromatographic conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

A high-throughput urinalysis of abused drugs based on a SPE-LC-MS/MS method coupled with an in-house developed post-analysis data treatment system.

PubMed

Cheng, Wing-Chi; Yau, Tsan-Sang; Wong, Ming-Kei; Chan, Lai-Ping; Mok, Vincent King-Kuen

2006-10-16

A rapid urinalysis system based on SPE-LC-MS/MS with an in-house post-analysis data management system has been developed for the simultaneous identification and semi-quantitation of opiates (morphine, codeine), methadone, amphetamines (amphetamine, methylamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA) and 3,4-methylenedioxymethamphetamine (MDMA)), 11-benzodiazepines or their metabolites and ketamine. The urine samples are subjected to automated solid phase extraction prior to analysis by LC-MS (Finnigan Surveyor LC connected to a Finnigan LCQ Advantage) fitted with an Alltech Rocket Platinum EPS C-18 column. With a single point calibration at the cut-off concentration for each analyte, simultaneous identification and semi-quantitation for the above mentioned drugs can be achieved in a 10 min run per urine sample. A computer macro-program package was developed to automatically retrieve appropriate data from the analytical data files, compare results with preset values (such as cut-off concentrations, MS matching scores) of each drug being analyzed and generate user-defined Excel reports to indicate all positive and negative results in batch-wise manner for ease of checking. The final analytical results are automatically copied into an Access database for report generation purposes. Through the use of automation in sample preparation, simultaneous identification and semi-quantitation by LC-MS/MS and a tailored made post-analysis data management system, this new urinalysis system significantly improves the quality of results, reduces the post-data treatment time, error due to data transfer and is suitable for high-throughput laboratory in batch-wise operation.

Development of an ion-pair HPLC method for investigation of energy charge changes in cerebral ischemia of mice and hypoxia of Neuro-2a cell line.

PubMed

Chen, Yunyun; Xing, Dongming; Wang, Wei; Ding, Yi; Du, Lijun

2007-06-01

The determination of adenine nucleotides and energy charge (EC) has great importance in the characterization of cerebral ischemic injury and post-ischemic recovery. An IP-HPLC method was developed for the quantification of AMP, ADP, ATP and EC in cerebral ischemia and hypoxia of the Neuro-2a cell line. The chromatographic conditions were: a Zorbax SB-C18 reversed-phase column; mobile phase 100 mM KH(2)PO(4), 1 mM tetrabutylammonium hydroxide, and 2.5% acetonitrile, brought to pH 7.0 with potassium hydroxide (4 M), filtered through a 0.45 microm Millipore filter and degassed prior to use. The flow-rate was 1.0 mL/min. The injection volume was 20 microL. Detection was performed at a wavelength of 254 nm under a constant temperature (27 +/- 1 degrees C). The method was validated by means of linearity, using calibration curves constructed with five concentration levels of each compound. The limit of detection was also determined. The system precision was calculated as the coefficient of variation for five injections for each compound tested. Cerebral tissue was homogenized (4 degrees C) in 1 mL of an ice-cold 6% trichloroacetic acid that contained ATPase inhibitor and obtained good recovery (>90%). The results show that the described method for the determination of adenine nucleotides by HPLC has good linearity, limit of detection, precision and specificity, and is simple and rapid to perform. Copyright 2007 John Wiley & Sons, Ltd.

A new estimation of HD/2H2 at high redshift using the spectrum of the quasar J 2123-0050

NASA Astrophysics Data System (ADS)

Klimenko, V. V.; Balashev, S. A.; Ivanchik, A. V.; Varshalovich, D. A.

2015-12-01

We present a new analysis of the quasar spectrum J 2123-0050 obtained using VLT/UVES. The H2/HD absorption system at z = 2.059 was analysed. This system consists of two subsystems with zA = 2.05933 and zB = 2.05955. The HD lines have been detected only in subsystem A with the column density of log N = 13.87 ± 0.06. We have determined the column density of H2 in this subsystem, log N = 17.93 ± 0.01, which is about three times larger than estimation derived early from analyses of quasar spectrum obtained using KECK/HIRES [1]. The derived ratio HD/2H2 = (4.28 ± 0.60) × 10-5 is the largest in quasar spectra, nevertheless it coincides with the primordial deuterium abundance within 2σ error. Additionally, we have found some evidence in the partial covering effect for the H2 system.

A flow-through column electrolytic cell for supercritical fluid chromatography.

PubMed

Yamamoto, Kazuhiro; Ueki, Tatsuya; Higuchi, Naoyuki; Takahashi, Kouji; Kotani, Akira; Hakamata, Hideki

2017-10-01

A novel flow-through column electrolytic cell was proposed as a detector to obtain current signals for supercritical fluid chromatography. The electrochemical cell consisted of two electrodes and its holder, and a working and a counter electrode were fabricated from 192 carbon strings, which were composed of 400 carbon fibers of 10 μm in diameter filled into a heat-shrinkable tube. These electrodes were placed in the center of a holder made from polyether ether ketone blocks and they were separated by polytetrafluoroethylene membrane filters. To evaluate the sensitivity of this cell, a standard solution of ferrocene was injected into the supercritical fluid chromatography system connected to the electrolytic cell. The ferrocene was eluted through a silica gel column using a mixture of a mobile phase of supercritical CO 2 and a modifier of methanol containing ammonium acetate. The current peak area of ferrocene correlated to the ferrocene concentration in the range of 10-400 μmol/L (r = 0.999). Moreover, the limit of detection on the column estimated from a signal-to-noise ratio of 3 was 9.8  × 10 -13  mol. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Overview of ISS U.S. Fire Detection and Suppression System

NASA Technical Reports Server (NTRS)

Whitaker, Alana

2003-01-01

This paper presents a general overview of the International Space Station's Fire Detection and Suppression System. The topics include: 1) Introduction to Fire Detection and Suppression (FDS); 2) Description of (FDS) Subsystems; 3) FDS System Component Location and Status; 4) FDS System Capabilities; 5) FDS Automatic and Manual Response; 6) Post Fire Atmosphere Restoration and Air Quality Assessment; and 7) FDS Research Needs. This paper is in viewgraph form.

New reversed phase-high performance liquid chromatographic method for selective separation of yttrium from all rare earth elements employing nitrilotriacetate complexes in anion exchange mode.

PubMed

Dybczyński, Rajmund S; Kulisa, Krzysztof; Pyszynska, Marta; Bojanowska-Czajka, Anna

2015-03-20

Separation of Y from other rare earth elements (REE) is difficult because of similarity of its ionic radius to ionic radii of Tb, Dy and Ho. In the new RP-HPLC system with C18 column, tetra-n-butyl ammonium hydroxide (TBAOH) as an ion interaction reagent (IIR), nitrilotriacetic acid (NTA) as a complexing agent at pH=2.8-3.5, and post column derivatization with Arsenazo III, yttrium is eluted in the region of light REE, between Nd and Sm and is base line separated from Nd and Sm and even from promethium. Simple model employing literature data on complex formation of REE with NTA and based on anion exchange mechanism was developed to foresee the order of elution of individual REE. The model correctly predicted that lanthanides up to Tb will be eluted in the order of increasing Atomic Number (At.No.) but all heavier REE will show smaller retention factors than Tb. Concurrent UV/VIS detection at 658nm and the use of radioactive tracers together with γ-ray spectrometric measurements made possible to establish an unique elution order of elution of REE: La, Ce, Pr, Nd, Pm, Y, Sm, Er, Ho, Tm, Yb, Eu, Lu, Dy+Gd, Tb, Sc. The real place of Y however, in this elution series differs from that predicted by the model (Y between Sm and Eu). The method described in this work enables selective separation of Y from La, Ce, Pr, Nd, Pm, Sm and all heavier REE treated as a group. Copyright © 2015 Elsevier B.V. All rights reserved.

Automation of an ion chromatograph for precipitation analysis with computerized data reduction

USGS Publications Warehouse

Hedley, Arthur G.; Fishman, Marvin J.

1982-01-01

Interconnection of an ion chromatograph, an autosampler, and a computing integrator to form an analytical system for simultaneous determination of fluoride, chloride, orthophosphate, bromide, nitrate, and sulfate in precipitation samples is described. Computer programs provided with the integrator are modified to implement ionchromatographic data reduction and data storage. The liquid-flow scheme for the ion chromatograph is changed by addition of a second suppressor column for greater analytical capacity. An additional vave enables selection of either suppressor column for analysis, as the other column is regenerated and stabilized with concentrated eluent.Minimum limits of detection and quantitation for each anion are calculated; these limits are a function of suppressor exhaustion. Precision for replicate analyses of six precipitation samples for fluoride, chloride, orthophosphate, nitrate, and sulfate ranged from 0.003 to 0.027 milligrams per liter. To determine accuracy of results, the same samples were spiked with known concentrations of the above mentioned anions. Average recovery was 108 percent.

Optrode for sensing hydrocarbons

DOEpatents

Miller, Holly; Milanovich, Fred P.; Hirschfeld, Tomas B.; Miller, Fred S.

1987-01-01

A two-phase system employing the Fujiwara reaction is provided for the fluorometric detection of halogenated hydrocarbons. A fiber optic is utilized to illuminate a column of pyridine trapped in a capillary tube coaxially attached at one end to the illuminating end of the fiber optic. A strongly alkaline condition necessary for the reaction is maintained by providing a reservoir of alkali in contact with the column of pyridine, the surface of contact being adjacent to the illuminating end of the fiber optic. A semipermeable membrane caps the other end of the capillary tube, the membrane being preferentially permeable to the halogenated hydrocarbon and but preferentially impermeable to water and pyridine. As the halogenated hydrocarbon diffuses through the membrane and into the column of pyridine, fluorescent reaction products are formed. Light propagated by the fiber optic from a light source, excites the fluorescent products. Light from the fluorescence emission is also collected by the same fiber optic and transmitted to a detector. The intensity of the fluorescence gives a measure of the concentration of the halogenated hydrocarbons.

Optrode for sensing hydrocarbons

DOEpatents

Miller, H.; Milanovich, F.P.; Hirschfeld, T.B.; Miller, F.S.

1987-05-19

A two-phase system employing the Fujiwara reaction is provided for the fluorometric detection of halogenated hydrocarbons. A fiber optic is utilized to illuminate a column of pyridine trapped in a capillary tube coaxially attached at one end to the illuminating end of the fiber optic. A strongly alkaline condition necessary for the reaction is maintained by providing a reservoir of alkali in contact with the column of pyridine, the surface of contact being adjacent to the illuminating end of the fiber optic. A semipermeable membrane caps the other end of the capillary tube, the membrane being preferentially permeable to the halogenated hydrocarbon but preferentially impermeable to water and pyridine. As the halogenated hydrocarbon diffuses through the membrane and into the column of pyridine, fluorescent reaction products are formed. Light propagated by the fiber optic from a light source, excites the fluorescent products. Light from the fluorescence emission is also collected by the same fiber optic and transmitted to a detector. The intensity of the fluorescence gives a measure of the concentration of the halogenated hydrocarbons. 6 figs.

Optrode for sensing hydrocarbons

DOEpatents

Miller, H.; Milanovich, F.P.; Hirschfeld, T.B.; Miller, F.S.

1988-09-13

A two-phase system employing the Fujiwara reaction is provided for the fluorometric detection of halogenated hydrocarbons. A fiber optic is utilized to illuminate a column of pyridine trapped in a capillary tube coaxially attached at one end to the illuminating end of the fiber optic. A strongly alkaline condition necessary for the reaction is maintained by providing a reservoir of alkali in contact with the column of pyridine, the surface of contact being adjacent to the illuminating end of the fiber optic. A semipermeable membrane caps the other end of the capillary tube, the membrane being preferentially permeable to the halogenated hydrocarbon and but preferentially impermeable to water and pyridine. As the halogenated hydrocarbon diffuses through the membrane and into the column of pyridine, fluorescent reaction products are formed. Light propagated by the fiber optic from a light source, excites the fluorescent products. Light from the fluorescence emission is also collected by the same fiber optic and transmitted to a detector. The intensity of the fluorescence gives a measure of the concentration of the halogenated hydrocarbons. 5 figs.

Optrode for sensing hydrocarbons

DOEpatents

Miller, Holly; Milanovich, Fred P.; Hirschfeld, Tomas B.; Miller, Fred S.

1988-01-01

A two-phase system employing the Fujiwara reaction is provided for the fluorometric detection of halogenated hydrocarbons. A fiber optic is utilized to illuminate a column of pyridine trapped in a capillary tube coaxially attached at one end to the illuminating end of the fiber optic. A strongly alkaline condition necessary for the reaction is maintained by providing a reservoir of alkali in contact with the column of pyridine, the surface of contact being adjacent to the illuminating end of the fiber optic. A semipermeable membrane caps the other end of the capillary tube, the membrane being preferentially permeable to the halogenated hydrocarbon and but preferentially impermeable to water and pyridine. As the halogenated hydrocarbon diffuses through the membrane and into the column of pyridine, fluorescent reaction products are formed. Light propagated by the fiber optic from a light source, excites the fluorescent products. Light from the fluorescence emission is also collected by the same fiber optic and transmitted to a detector. The intensity of the fluorescence gives a measure of the concentration of the halogenated hydrocarbons.

A new tool for the rapid remote detection of leaks from subsea pipelines during remotely operated vehicle inspections

NASA Astrophysics Data System (ADS)

McStay, D.; McIlroy, J.; Forte, A.; Lunney, F.; Greenway, T.; Thabeth, K.; Dean, G.

2005-06-01

A new 2000 m depth rated subsea sensor that can effectively, rapidly and remotely detect leaks of fluorescein dye, leak detection chemicals and hydraulic fluids from underwater structures is reported. The system utilizes ultra-bright LED technology to project a structured beam of light, at a wavelength suitable to excite the fluorescence of the target material, into the water column. The resultant fluorescence is collected and digital signal processing used to extract the intensity. The system is capable of detecting ppm concentrations of fluorescein at a range of 2.5 m in water in real time. The ability to stand-off from subsea structures, while rapidly detecting the chemicals makes the system highly suited to subsea leak inspections with remotely operated vehicles or autonomous underwater vehicles, as it allows the vehicles to be flown quickly and safely over the structure to be inspected. This increases both the speed and effectiveness of the inspection. The remote detection capability is also highly effective for probing complex underwater structures. The system has been successfully used in real subsea survey applications and has been found to be effective, user friendly and to dramatically reduce inspection times and hence costs.

Influence of detergent formulation on nutrient movement through sand columns simulating mound and conventional septic system drainfields

NASA Astrophysics Data System (ADS)

Alhajjar, Bashar J.; Linn Gould, C.; Chesters, Gordon; Harkin, John M.

1990-12-01

The effects of phosphate (P) and zeolite (Z) -built detergents on leaching of N and P through sand columns simulating septic system drainfields were examined in laboratory columns. To simulate mound septic system drainfields, paired sets of columns were dosed intermittently with septic tank effluent from households using P- or Z-built detergent. Two other paired sets of columns were flooded with P- or Z-effluent to simulate new conventional septic system drainfields; after clogging mats or "crusts" developed at infiltration surface, the subsurfaces of the columns were aerated to simulate mature (crusted) conventional septic system drainfields. NO 3 loading in leachate was 1.1 times higher and ortho-P loading was 4.3 times lower when columns were dosed with Z- than with P-effluent. Dosed columns removed P poorly; total phosphorus (TP) loading in leachate was 81 and 19 g m -2 yr -1 with P- and Z-effluent, respectively. In flooded columns 1.3, 2.0 and 1.8 times more NH 4, organic nitrogen (ON) and total nitrogen (TN) respectively, were leached with Z- than with P-effluent; NO 3 leaching was similar. Flooded columns removed P efficiently; TP leached through flooded systems was 2.5 and 1.4 g m -2 yr -1 with P- and Z effluent, respectively. Crusted columns fed Z-effluent leached 1.2, 2.6, 1.4 and 2.1 times more NH 4, NO 3, ON and TN, respectively, than those with P-effluent but 1.8 times less TP. Crusted columns removed P satisfactorily: 8.2 and 4.6 g m -2 yr -1 TP with P- and Z-effluent, respectively. The P-built detergent substantially improves the efficiency of N removal with satisfactory P removal in columns simulating conventional septic system drainfield. Simultaneous removal of N and P under flooded conditions might be explained by precipitation of struvite-type minerals. Dosed system drainfields were less efficient in removing N and P compared to flooded and crusted system drainfelds.

Prediction of shear critical behavior of high-strength reinforced concrete columns using finite element methods

NASA Astrophysics Data System (ADS)

Alrasyid, Harun; Safi, Fahrudin; Iranata, Data; Chen-Ou, Yu

2017-11-01

This research shows the prediction of shear behavior of High-Strength Reinforced Concrete Columns using Finite-Element Method. The experimental data of nine half scale high-strength reinforced concrete were selected. These columns using specified concrete compressive strength of 70 MPa, specified yield strength of longitudinal and transverse reinforcement of 685 and 785 MPa, respectively. The VecTor2 finite element software was used to simulate the shear critical behavior of these columns. The combination axial compression load and monotonic loading were applied at this prediction. It is demonstrated that VecTor2 finite element software provides accurate prediction of load-deflection up to peak at applied load, but provide similar behavior at post peak load. The shear strength prediction provide by VecTor 2 are slightly conservative compare to test result.

Glycolipid class profiling by packed-column subcritical fluid chromatography.

PubMed

Deschamps, Frantz S; Lesellier, Eric; Bleton, Jean; Baillet, Arlette; Tchapla, Alain; Chaminade, Pierre

2004-06-18

The potential of packed-column subcritical fluid chromatography (SubFC) for the separation of lipid classes has been assessed in this study. Three polar stationary phases were checked: silica, diol, and poly(vinyl alcohol). Carbon dioxide (CO2) with methanol as modifier was used as mobile phase and detection performed by evaporative light scattering detection. The influence of methanol content, temperature, and pressure on the chromatographic behavior of sphingolipids and glycolipids were investigated. A complete separation of lipid classes from a crude wheat lipid extract was achieved using a modifier gradient from 10 to 40% methanol in carbon dioxide. Solute selectivity was improved using coupled silica and diol columns in series. Because the variation of eluotropic strength depending on the fluid density changes, a normalized separation factor product (NSP) was used to select the nature, the number and the order of the columns to reach the optimum glycolipid separation.

Distillation Column Flooding Predictor

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

George E. Dzyacky

2010-11-23

The Flooding Predictor™ is a patented advanced control technology proven in research at the Separations Research Program, University of Texas at Austin, to increase distillation column throughput by over 6%, while also increasing energy efficiency by 10%. The research was conducted under a U. S. Department of Energy Cooperative Agreement awarded to George Dzyacky of 2ndpoint, LLC. The Flooding Predictor™ works by detecting the incipient flood point and controlling the column closer to its actual hydraulic limit than historical practices have allowed. Further, the technology uses existing column instrumentation, meaning no additional refining infrastructure is required. Refiners often push distillationmore » columns to maximize throughput, improve separation, or simply to achieve day-to-day optimization. Attempting to achieve such operating objectives is a tricky undertaking that can result in flooding. Operators and advanced control strategies alike rely on the conventional use of delta-pressure instrumentation to approximate the column’s approach to flood. But column delta-pressure is more an inference of the column’s approach to flood than it is an actual measurement of it. As a consequence, delta pressure limits are established conservatively in order to operate in a regime where the column is never expected to flood. As a result, there is much “left on the table” when operating in such a regime, i.e. the capacity difference between controlling the column to an upper delta-pressure limit and controlling it to the actual hydraulic limit. The Flooding Predictor™, an innovative pattern recognition technology, controls columns at their actual hydraulic limit, which research shows leads to a throughput increase of over 6%. Controlling closer to the hydraulic limit also permits operation in a sweet spot of increased energy-efficiency. In this region of increased column loading, the Flooding Predictor is able to exploit the benefits of higher liquid/vapor traffic that produce increased contact area and lead to substantial increases in separation efficiency – which translates to a 10% increase in energy efficiency on a BTU/bbl basis. The Flooding Predictor™ operates on the principle that between five to sixty minutes in advance of a flooding event, certain column variables experience an oscillation, a pre-flood pattern. The pattern recognition system of the Flooding Predictor™ utilizes the mathematical first derivative of certain column variables to identify the column’s pre-flood pattern(s). This pattern is a very brief, highly repeatable, simultaneous movement among the derivative values of certain column variables. While all column variables experience negligible random noise generated from the natural frequency of the process, subtle pre-flood patterns are revealed among sub-sets of the derivative values of column variables as the column approaches its hydraulic limit. The sub-set of column variables that comprise the pre-flood pattern is identified empirically through in a two-step process. First, 2ndpoint’s proprietary off-line analysis tool is used to mine historical data for pre-flood patterns. Second, the column is flood-tested to fine-tune the pattern recognition for commissioning. Then the Flooding Predictor™ is implemented as closed-loop advanced control strategy on the plant’s distributed control system (DCS), thus automating control of the column at its hydraulic limit.« less

Big Data Analysis of Manufacturing Processes

NASA Astrophysics Data System (ADS)

Windmann, Stefan; Maier, Alexander; Niggemann, Oliver; Frey, Christian; Bernardi, Ansgar; Gu, Ying; Pfrommer, Holger; Steckel, Thilo; Krüger, Michael; Kraus, Robert

2015-11-01

The high complexity of manufacturing processes and the continuously growing amount of data lead to excessive demands on the users with respect to process monitoring, data analysis and fault detection. For these reasons, problems and faults are often detected too late, maintenance intervals are chosen too short and optimization potential for higher output and increased energy efficiency is not sufficiently used. A possibility to cope with these challenges is the development of self-learning assistance systems, which identify relevant relationships by observation of complex manufacturing processes so that failures, anomalies and need for optimization are automatically detected. The assistance system developed in the present work accomplishes data acquisition, process monitoring and anomaly detection in industrial and agricultural processes. The assistance system is evaluated in three application cases: Large distillation columns, agricultural harvesting processes and large-scale sorting plants. In this paper, the developed infrastructures for data acquisition in these application cases are described as well as the developed algorithms and initial evaluation results.

Chromatographic column evaluation for the untargeted profiling of glucosinolates in cauliflower by means of ultra-high performance liquid chromatography coupled to high resolution mass spectrometry.

PubMed

Capriotti, Anna Laura; Cavaliere, Chiara; La Barbera, Giorgia; Montone, Carmela Maria; Piovesana, Susy; Zenezini Chiozzi, Riccardo; Laganà, Aldo

2018-03-01

The untargeted profiling is a promising approach for the characterization of secondary metabolites in biological matrices. Thanks to the recent rapid development of high-resolution mass spectrometry (HRMS) instrumentations, the number of applications by untargeted approaches for biological samples profiling has widely increased in the recent years. Despite the high potentialities of HRMS, however, a major issue in natural products analysis often arises in the upstream process of compounds separation. A separation technique is necessary to avoid phenomena such as signal suppression, and it is especially needed in the presence of isomeric metabolites, which are otherwise indistinguishable. Glucosinolates (GLSs), a group of secondary metabolites widely distributed among plants, resulted to be associated to the prevention of some serious diseases, such as cancer. This led to the development of several methods for the analysis of GLSs in vegetables tissues. The issue of GLSs chromatographic separation has been widely studied in the past because of the difficulty in the analysis of this highly polar and variable class of compounds. Several alternatives to reversed phase (RP) chromatography, sometimes not compatible with the coupling of liquid chromatography with mass spectrometry, have been tested for the analysis of intact GLSs. However, the availability of new stationary phases, in the last years, could allow the re-evaluation of RP chromatography for the analysis of intact GLSs. In this work, a thorough evaluation of four RP chromatographic columns for the analysis of GLSs in cauliflower (Brassica oleracea L. var. botrytis) extracts by an ultra-high performance liquid chromatographic system coupled via electrospray source to a hybrid quadrupole-Orbitrap mass spectrometer is presented. The columns tested were the following: one column Luna Omega polar C 18 , one column Kinetex Biphenyl, one column Kinetex core-shell XB-C 18 , two columns Kinetex core-shell XB-C 18 . After a previous optimization of the extraction method, cauliflower extracts were analyzed testing four different mobile phases onto the four columns for a total of sixteen different chromatographic conditions. The chromatographic systems were evaluated based on the number of detected and tentatively identified GLSs. Luna Polar stationary phase resulted to be the most suitable for the analysis of GLSs compared to Kinetex XB and Kinetex Biphenyl columns stationary phase. However, two in series Kinetex XB columns increased the number of tentatively identified GLSs compared to one Kinetex XB, showing the importance of column length in the analysis of complex mixtures. The data obtained with the best chromatographic system were deeply analyzed by MS/MS investigation for the final identification. Fiflty-one GLSs were tentatively identified, 24 of which have never been identified in cauliflower. Finally the linearity of the analytes response over the analyzed range of concentration was checked, suggesting that the developed method is suitable for both qualitative and quantitative analysis of GLSs in phytochemical mixtures. Copyright © 2017 Elsevier B.V. All rights reserved.

Silver-modified mobile phase for normal-phase liquid chromatographic determination of prostaglandins and their 5,6-trans isomers in prostaglandin bulk drugs and triacetin solutions.

PubMed

Kissinger, L D; Robins, R H

1985-03-15

A silver-modified, normal-phase, high-performance liquid chromatographic system has been developed for prostaglanding bulk drugs and triacetin solutions. Silver nitrate present in the mobile phase results in high selectivity for cis/trans isomers with conventional silica columns. Prostaglandins were esterified with alpha-bromo-2'-acetonaphthone prior to chromatography to provide high detectability at 254 nm. For dilute triacetin solutions, a sample preparation scheme based on gravity-flow chromatography with silica columns was developed to isolate the prostaglandin from triacetin prior to derivatization. The analytical technique was applied to triacetin solutions containing as little as 10 micrograms/ml arbaprostil [15-(R)-methyl-PGE2].

Supramolecular Affinity Chromatography for Methylation-Targeted Proteomics.

PubMed

Garnett, Graham A E; Starke, Melissa J; Shaurya, Alok; Li, Janessa; Hof, Fraser

2016-04-05

Proteome-wide studies of post-translationally methylated species using mass spectrometry are complicated by high sample diversity, competition for ionization among peptides, and mass redundancies. Antibody-based enrichment has powered methylation proteomics until now, but the reliability, pan-specificity, polyclonal nature, and stability of the available pan-specific antibodies are problematic and do not provide a standard, reliable platform for investigators. We have invented an anionic supramolecular host that can form host-guest complexes selectively with methyllysine-containing peptides and used it to create a methylysine-affinity column. The column resolves peptides on the basis of methylation-a feat impossible with a comparable commercial cation-exchange column. A proteolyzed nuclear extract was separated on the methyl-affinity column prior to standard proteomics analysis. This experiment demonstrates that such chemical methyl-affinity columns are capable of enriching and improving the analysis of methyllysine residues from complex protein mixtures. We discuss the importance of this advance in the context of biomolecule-driven enrichment methods.

Automation of nanoflow liquid chromatography-tandem mass spectrometry for proteome analysis by using a strong cation exchange trap column.

PubMed

Jiang, Xiaogang; Feng, Shun; Tian, Ruijun; Han, Guanghui; Jiang, Xinning; Ye, Mingliang; Zou, Hanfa

2007-02-01

An approach was developed to automate sample introduction for nanoflow LC-MS/MS (microLC-MS/MS) analysis using a strong cation exchange (SCX) trap column. The system consisted of a 100 microm id x 2 cm SCX trap column and a 75 microm id x 12 cm C18 RP analytical column. During the sample loading step, the flow passing through the SCX trap column was directed to waste for loading a large volume of sample at high flow rate. Then the peptides bound on the SCX trap column were eluted onto the RP analytical column by a high salt buffer followed by RP chromatographic separation of the peptides at nanoliter flow rate. It was observed that higher performance of separation could be achieved with the system using SCX trap column than with the system using C18 trap column. The high proteomic coverage using this approach was demonstrated in the analysis of tryptic digest of BSA and yeast cell lysate. In addition, this system was also applied to two-dimensional separation of tryptic digest of human hepatocellular carcinoma cell line SMMC-7721 for large scale proteome analysis. This system was fully automated and required minimum changes on current microLC-MS/MS system. This system represented a promising platform for routine proteome analysis.

Sulfur speciation and sulfide oxidation in the water column of the Black Sea

NASA Astrophysics Data System (ADS)

Luther, George W., III; Church, Thomas M.; Powell, David

We have applied sulfur speciation techniques to understand the chemistry and cycling of sulfur in Black Sea waters. The only reduced dissolved inorganic sulfur species detected (above the low minimum detection limits of the voltammetric methods employed) in the water column was hydrogen sulfide. The maximum concentration of sulfide (423 μM) is similar to previous reports. Using a cathodic stripping square wave voltammetry (CSSWV) method for nanomolar levels of sulfide, we determined the precise boundary between the "free" hydrogen sulfide (sulfidic) zone and the upper (oxic/suboxic) water column at the two stations studied. This boundary has apparently moved up by about 50 m in the past 20 years. Our results help demonstrate three chemically distinct zones of water in the central basin of the Black Sea: (1) the oxic [0-65 m], (2) the anoxic/nonsulfidic [65-100 m] and (3) the sulfidic [>100 m]. Sulfide bound to metals ("complexed" sulfide) is observed in both the oxic and anoxic/nonsulfidic zones of the water column. This supports previous studies on metal sulfide forms. From the electrochemical data, it is possible to estimate the strength of the complexation of sulfide to metals (log K = 10 to 11). Thiosulfate and sulfite were below our minimum detectable limit (MDL) of 50 nM using CSSWV. Elemental sulfur (MDL 5 nM) was detected below the onset of the hydrogen sulfide zone (90-100 m) with a maximum of 30-60 nM near 120 m. The sulfur speciation results for the Black Sea are lower by one order of magnitude or more than other marine systems such as the Cariaco Trench and salt marshes. New HPLC techniques were applied to detect thiols at submicromolar levels. The presence of thiols (2-mercaptoethylamine, 2-mercaptoethanol, N-acetylcysteine and glutathione) is correlated with the remineralization of organic matter at the oxic and anoxic/nonsulfidic interface. Water samples collected from the upper 50 m of the sulfidic zone showed significant sulfide oxidation on storage onboard ship even though they were filtered (0.2 μm) and handled to exclude oxygen contamination. Chemical additives such as formaldehyde, glutaraldehyde, hydroxylamine and ascorbic acid prevented or retarded the sulfide loss. Thiosulfate and azide did not inhibit sulfide loss. These studies suggest an anaerobic chemical oxidation of sulfide rather than a biological oxidation on stored and filtered samples.

Rapid, direct determination of polyphenols in tea by reversed-phase column liquid chromatography.

PubMed

Ding, M; Yang, H; Xiao, S

1999-07-23

Column liquid chromatography on a C18-bonded silica column with water-methanol-acetic acid as eluent was used to determine polyphenols and caffeine in tea. Without any pretreatment, catechin, epicatechin gallate, epigallocatechin gallate, epigallocatechin, epicatechin and caffeine were separated successfully within 15 min. The detection limits (S/N = 3) of polyphenols studied were 1.8-24 mg/l at a detection wavelength 270 nm. The linear range of the peak area calibration curves for the analytes were over two orders of magnitude with a correlation coefficient of 0.996-0.999. Using this method, some Chinese tea samples were analyzed with a good reproducibility (RSD are below 5%).

Environmental monitoring of bleached kraft pulp mill chlorophenolic compounds in a northern Canadian river system.

PubMed

Owens, J W; Swanson, S M; Birkholz, D A

1994-07-01

The environmental transport of pulp mill effluent compounds and the exposure of two fish species has been monitored by parallel analyses of effluent, water column and suspended sediment samples, and fish bile and muscle. Compounds analyzed included over 20 chlorophenolic compounds and 12 fatty and resin acids. The concentration of chlorophenols varied with seasonal river flows and mill process changes such as the substitution of chlorine dioxide (ClO2) for chlorine gas (Cl2) in the bleach plant. At 100% (ClO2) substitution, the effluent and the water column concentrations of most chlorophenolics approached the analytical detection limits of 0.1-1 parts per billion. Chlorophenolic and fatty/resin acid compounds were detected in the bile of both mountain whitefish (Prosopium williamsoni) and longnose sucker (Catostomus catostomus), but were rarely detected in fillets. Fish bile concentrations were observed in an apparent spatial gradient as far as 230 km downstream of the mill. A depuration experiment with fish held in uncontaminated water for eight days indicated a rapid decrease in chlorophenol levels. These observations corroborate previous investigations that chlorophenolic compounds are rapidly excreted and can be used as sensitive markers for recent exposure to mill effluents.

Suspension column for recovery and separation of substances using ultrasound-assisted retention of bead sorbents.

PubMed

Spivakov, Boris Ya; Shkinev, Valeriy M; Danilova, Tatiana V; Knyazkov, Nikolai N; Kurochkin, Vladimir E; Karandashev, Vasiliy K

2012-12-15

A novel approach to sorption recovery and separation of different substances is proposed which is based on the use of suspended bead sorbents instead of conventional packed beds of such sorbents. This makes it possible to employ small-sized beads which are trapped in a low-pressure column due to ultrasound-assisted retention, without any frits to hold the sorption material. A flow system including a separation mini-column, named herein a suspension column, has been developed and tested by the studies of solid phase extraction (SPE) of trace metals from bi-distilled water and sea water using a 150-μL column with a silica-based sorbent containing iminodiacetic groups (DIAPAK IDA) and having a grain size of 6 μm. The adsorption properties of DIAPAK IDA suspension (9.5mg) were evaluated through adsorption/desorption experiments, where the effect of solution pH and eluent on the SPE of trace metals were examined by ICP-MS or ICP-AES measurements. When sample solution was adjusted to pH 8.0 and 1 mol L(-1) nitric acid was used as eluent, very good recoveries of more than 90% were obtained for a number of elements in a single-step extraction. To demonstrate the versatility of the approach proposed and to show another advantage of ultrasonic field (acceleration of sorbate/sorbent interaction), a similar system was used for heterogeneous immunoassays of some antigens in ultrasonic field using agarose sorbents modified by corresponding antibodies. It has been shown that immunoglobulins, chlamidia, and brucellos bacteria can be quantitatively adsorbed on 15-μm sorbent (15 particles in 50 μL) and directly determined in a 50-μL mini-chamber using fluorescence detection. Copyright © 2012 Elsevier B.V. All rights reserved.

Determination of thiopental in urine sample with high-performance liquid chromatography using iodine-azide reaction as a postcolumn detection system.

PubMed

Zakrzewski, Robert; Ciesielski, Witold

2005-09-25

The reaction between iodine and azide ions induced by thiopental was utilized as a postcolumn reaction for chromatographic determination of thiopental. The method is based on the separation of thiopental on an Nova-Pak CN HP column with an acetonitrile-aqueous solution of sodium azide as a mobile phase, followed by spectrophotometric measurement of the residual iodine (lambda=350 nm) from the postcolumn iodine-azide reaction induced by thiopental after mixing an iodine solution containing iodide ions with the column effluent containing azide ions and thiopental. Chromatograms obtained for thiopental showed negative peaks as a result of the decrease in background absorbance. The detection limit (defined as S/N=3) was 20 nM (0.4 pmol injected amount) for thiopental. Calibration graphs, plotted as peak area versus concentrations, were linear from 40 nM. The elaborated method was applied to determine thiopental in urine samples. The detection limit (defined as S/N=3) was 0.025 nmol/ml urine. Calibration graphs, plotted as peak area versus concentrations, were linear from 0.05 nmol/ml urine. Authentic urine samples were analyzed, thiopental was determined at nmol/ml urine level.

In Situ Repair of Deteriorated Concrete in Hydraulic Structures: Feasibility Study

DTIC Science & Technology

1987-05-01

because of its severe deterioration. Examination of the structure had revealed extensive cracking in the beams , columns , and walls as well as pockets of...used extensively in hydraulic structures, such as dams, spill- ways, lock chambers, and bridge support columns and piers. The Corps of Engineers...Figure 6. Repair of crack by post reinforcement. lli FORM KEY WITH PRECAST CONCRETE OR MORTAR PLUGS SET IN BITI.MEN, HoLE DRILLED IN STEM OF WALL

An Ultra-Trace Analysis Technique for SF6 Using Gas Chromatography with Negative Ion Chemical Ionization Mass Spectrometry.

PubMed

Jong, Edmund C; Macek, Paul V; Perera, Inoka E; Luxbacher, Kray D; McNair, Harold M

2015-07-01

Sulfur hexafluoride (SF6) is widely used as a tracer gas because of its detectability at low concentrations. This attribute of SF6 allows the quantification of both small-scale flows, such as leakage, and large-scale flows, such as atmospheric currents. SF6's high detection sensitivity also facilitates greater usage efficiency and lower operating cost for tracer deployments by reducing quantity requirements. The detectability of SF6 is produced by its high molecular electronegativity. This property provides a high potential for negative ion formation through electron capture thus naturally translating to selective detection using negative ion chemical ionization mass spectrometry (NCI-MS). This paper investigates the potential of using gas chromatography (GC) with NCI-MS for the detection of SF6. The experimental parameters for an ultra-trace SF6 detection method utilizing minimal customizations of the analytical instrument are detailed. A method for the detection of parts per trillion (ppt) level concentrations of SF6 for the purpose of underground ventilation tracer gas analysis was successfully developed in this study. The method utilized a Shimadzu gas chromatography with negative ion chemical ionization mass spectrometry system equipped with an Agilent J&W HP-porous layer open tubular column coated with an alumina oxide (Al2O3) S column. The method detection limit (MDL) analysis as defined by the Environmental Protection Agency of the tracer data showed the method MDL to be 5.2 ppt. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Portable, lightweight, low power, ion chromatographic system with open tubular capillary columns.

PubMed

Kiplagat, Isaac K; Kubán, Petr; Pelcová, Pavlína; Kubán, Vlastimil

2010-07-30

Basic operation principles of a lightweight, low power, low cost, portable ion chromatograph utilizing open tubular ion chromatography in capillary columns coated with multi-layer polymeric stationary phases are demonstrated. A minimalistic configuration of a portable IC instrument was developed that does not require any chromatographic eluent delivery system, nor sample injection device as it uses gravity-based eluent flow and hydrodynamic sample injection adopted from capillary electrophoresis. As a detection device, an inexpensive commercially available capacitance sensor is used that has been shown to be a suitable substitute for contactless conductivity detection in capillary separation systems. The built-in temperature sensor allows for baseline drift correction typically encountered in conductivity/capacitance measurements without thermostating device. The whole instrument does not require any power supply for its operation, except the detection and data acquisition part that is provided by a USB port of a Netbook computer. It is extremely lightweight, its total weight including the Netbook computer is less than 2.5kg and it can be continuously operated for more than 8h. Several parameters of the instrument, such as detection cell design, eluent delivery systems and data treatment were optimized as well as the composition of eluent for non-suppressed ion chromatographic analysis of common inorganic cations (Na(+), NH(4)(+), K(+), Cs(+), Ca(2+), Mg(2+), transition metals). Low conductivity eluents based on weakly complexing organic acids such as tartaric, oxalic or pyridine-2,6-dicarboxylic acids were used with contactless capacitance detection for simultaneous separation of mono- and divalent cations. Separation of Na(+) and NH(4)(+) cations was optimized by addition of 18-crown-6 to the eluent. The best separation of 6 metal cations commonly present in various environmental samples was accomplished in less than 30min using a 1.75mM pyridine-2,6-dicarboxylic acid and 3mM 18-crown-6 eluent with excellent repeatability (below 2%) and detection limits in the low micromolar range. The analysis of field samples is demonstrated; the concentrations of common inorganic cations in river water, mineral water and snow samples were determined.

The separation of leukotrienes and hydroxyeicosatetraenoic acid metabolites of arachidonic acid by high performance liquid chromatography (HPLC).

PubMed

Osborne, D J; Peters, B J; Meade, C J

1983-11-01

The following high performance liquid chromatography system was found suitable for separating most lipoxygenase metabolites of arachidonic acid: Techsphere 5-C18 column, eluting solvent methanol:water:acetic acid (65:35:0.06 v/v), pH 5.3. Comparisons with other packing materials and solvent systems are described. The method could be used to identify lipoxygenase products released from mouse macrophage cells stimulated with gamma-hexachlorocyclohexane. Detection limits between 1 and 10 ng were obtained.

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

Mahmood, U; Dauer, L; Erdi, Y

Purpose: Our goal was to evaluate low contrast detectability (LCD) for abdominal CT protocols across two CT scanner manufacturers, while producing a similar noise texture and CTDIvol for acquired images. Methods: A CIRS tissue equivalent LCD phantom containing three columns of 7 spherical targets, ranging from 10 mm to 2.4 mm, that are 5, 10, and 20 HU below the background matrix (HUBB) was scanned using two a GE HD750 64 slice scanner and a Siemens Somatom Definition AS 64 slice scanner. Protocols were designed to deliver a CTDIvol of 12.26 mGy and images were reconstructed with FBP, ASIR andmore » Sapphire. Comparisons were made with those algorithms that had matching noise power spectrum peaks (NPS). NPS information was extracted from a previously published article that matched NPS peak frequencies across manufacturers by calculating the NPS from uniform phantom images reconstructed with several IR algorithms. Results: The minimum detectable lesion size in the 20 HUBB and 10 HUBB column was 6.3 mm, and 10 mm in the 5 HUBB column for the GE HD 750 scanner. The minimum detectable lesion size in the 20 HUBB column was 4.8 mm, in the 10 HUBB column, 9.5 mm, and the 5 HUBB column, 10 mm for the Siemens Somatom Definition AS. Conclusion: Reducing radiation dose while improving or maintaining LCD is possible with application of IR. However, there are several different IR algorithms, with each generating a different resolution and noise texture. In multi-manufacturer settings, matching only the CTDIvol between manufacturers may Result in a loss of clinically relevant information.« less

Ion chromatography for determination of nitrite and nitrate in seawater using monolithic ODS columns.

PubMed

Ito, Kazuaki; Takayama, Yohichi; Makabe, Nobuyuki; Mitsui, Ryo; Hirokawa, Takeshi

2005-08-12

A fast and highly sensitive ion chromatographic method using monolithic ODS columns was developed for the determination of nitrite (NO2-) and nitrate (NO3-) in seawater. Two monolithic ODS columns (50 mm x 4.6 mm i.d. + 100 mm x 4.6 mm i.d.) connected in series were coated and equilibrated with 5 mM cetyltrimethylammonium chloride (CTAC) aqueous solution. The column efficiency with 0.5 M NaCl as the mobile phase did not decrease in spite of the increase in flow rate of the mobile phase. Thus, good chromatograms were obtained within 3 minutes for NO2- and NO3 in artificial seawater without interferences by coexisting ions. The detection limit (S/N = 3) with UV detection at 225 nm was 0.8 and 1.6 microg/L for NO2- and NO3-, respectively. The characteristics of the monolithic CTA(+)-coated ODS columns were discussed. The present method was successfully applied to the fast and sensitive determination of NO2- and NO3- in real seawater samples.

Polymeric monolith column composited with multiwalled carbon nanotubes-β-cyclodextrin for the selective extraction of psoralen and isopsoralen.

PubMed

Ling, Xu; Zou, Li; Chen, Zilin

2017-09-01

A polymeric column that contains multiwalled carbon nanotubes-β-cyclodextrin composite was developed. The composite was wrapped into the poly(butyl methacrylate-ethylene dimethacrylate) monolith column (0.76 mm id and 10 cm in length). The column was then applied for the online solid-phase microextraction of psoralen and isopsoralen from Fructus Psoraleae. Following microextraction, the coumarins were quantified by high-performance liquid chromatography with C 18 separation column and UV detection. The effects of sample flow rate, sample volume, and pH value were optimized. The method showed low limits of detection (20 pg/mL, S/N = 3) for both psoralen and isopsoralen. Finally the method was successfully applied to the determination of psoralen and isopsoralen in spiked herb extracts and rat plasma where it gave recoveries that ranged between 93.2 and 102.1%. The empty hydrophobic cavities of β-cyclodextrin and the hydrophobicity of multiwalled carbon nanotubes provided specific extraction capability for psoralen and isopsoralen. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quantification of low molecular weight selenium metabolites in human plasma after treatment with selenite in pharmacological doses by LC-ICP-MS.

PubMed

Flouda, Konstantina; Dersch, Julie Maria; Gabel-Jensen, Charlotte; Stürup, Stefan; Misra, Sougat; Björnstedt, Mikael; Gammelgaard, Bente

2016-03-01

The paper presents an analytical method for quantification of low molecular weight (LMW) selenium compounds in human plasma based on liquid chromatography inductively coupled plasma mass spectrometry (LC-ICP-MS) and post column isotope dilution-based quantification. Prior to analysis, samples were ultrafiltrated using a cut-off value of 3000 Da. The method was validated in aqueous solution as well as plasma using standards of selenomethionine (SeMet), Se-methylselenocysteine (MeSeCys), selenite, and the selenosugar Se-methylseleno-N-acetylgalactosamine (SeGal) for linearity, precision, recoveries, and limits of detection and quantitation with satisfactory results. The method was applied for analysis of a set of plasma samples from cancer patients receiving selenite treatment in a clinical trial. Three LMW selenium compounds were observed. The main compounds, SeGal and selenite were tentatively identified by retention time matching with standards in different chromatographic systems, while the third minor compound was not identified. The identity of the selenosugar was verified by ESI-MS-MS product ion scanning, while selenite was identified indirectly as the glutathione (GSH) reaction product, GS-Se-SG.

Automatic small target detection in synthetic infrared images

NASA Astrophysics Data System (ADS)

Yardımcı, Ozan; Ulusoy, Ä.°lkay

2017-05-01

Automatic detection of targets from far distances is a very challenging problem. Background clutter and small target size are the main difficulties which should be solved while reaching a high detection performance as well as a low computational load. The pre-processing, detection and post-processing approaches are very effective on the final results. In this study, first of all, various methods in the literature were evaluated separately for each of these stages using the simulated test scenarios. Then, a full system of detection was constructed among available solutions which resulted in the best performance in terms of detection. However, although a precision rate as 100% was reached, the recall values stayed low around 25-45%. Finally, a post-processing method was proposed which increased the recall value while keeping the precision at 100%. The proposed post-processing method, which is based on local operations, increased the recall value to 65-95% in all test scenarios.

[Examples for using capillary gas chromatography with wide bore columns in occupational health].

PubMed

Frank, H; Senf, L; Welsch, T

1990-12-01

Wide bore capillary columns (0.4-0.75 mm ID) can be easily and inexpensively installed in packed column GCs. The analytical advantages cause an expanding market for such capillaries and interconverting hardware kits. It is illustrated with some examples that often individual exposition levels can be determined exactly only by using capillary columns: ethylbenzene may be separated from the C8-isomers also in complex mixtures, the marker PBN for rubber smoke expositions can be determined with 30 min sampling time, the detection sensitivity of the FID is sufficient also for chlorinated pesticides and the analyses of high-boiling compounds profit by the high phase ratio of wide bore capillary columns. A single capillary column substitutes a variety of different packed columns, so saving time and money and protecting the analyst from failures and frustrating compromises.

The O VI Mystery: Mismatch between X-Ray and UV Column Densities

NASA Astrophysics Data System (ADS)

Mathur, S.; Nicastro, F.; Gupta, A.; Krongold, Y.; McLaughlin, B. M.; Brickhouse, N.; Pradhan, A.

2017-12-01

The UV spectra of Galactic and extragalactic sightlines often show O VI absorption lines at a range of redshifts, and from a variety of sources from the Galactic circumgalactic medium to active galactic nuclei (AGN) outflows. Inner shell O VI absorption is also observed in X-ray spectra (at λ =22.03 Å), but the column density inferred from the X-ray line was consistently larger than that from the UV line. Here we present a solution to this discrepancy for the z = 0 systems. The O II Kβ line {}4{S}0\\to {(}3D)3{p}4P at 562.40 eV (≡22.04 Å) is blended with the O VI Kα line in X-ray spectra. We estimate the strength of this O II line in two different ways, and show that in most cases the O II line accounts for the entire blended line. The small amount of O VI equivalent width present in some cases has column density entirely consistent with the UV value. This solution to the O VI discrepancy, however, does not apply to high column-density systems like AGN outflows. We discuss other possible causes to explain their UV/X-ray mismatch. The O VI and O II lines will be resolved by gratings on board the proposed mission Arcus and the concept mission Lynx, and would allow the detection of weak O VI lines not just at z = 0, but also at higher redshift.

PLIF in thoracolumbar trauma: technique and radiological results

PubMed Central

Dietmar, Krappinger; Peter, Seykora; Michael, Blauth; Anton, Kathrein

2010-01-01

Patients with fractures from the 11th thoracic to the 5th lumbar vertebra had a reconstruction of the anterior column with monocortical iliac crest autograft by using a single dorsal approach. The loss of correction was observed using X-rays pre- and post-operatively, at 3 months and after implant removal (IR). Successful fusion was assessed using computed tomography after the implant removal. To assess the loss of correction and intervertebral fusion rate of this technique. There are still controversial discussions about the treatment modalities of spine lesions, especially in cases of burst fractures. Dorsal, combined and ventral procedures are reported with different assets and drawbacks. We want to present a method to restore the weight-bearing capability of the anterior column using a single dorsal approach. From 2001 to 2005, a total of 100 patients was treated with this technique at our department. Follow-up examination was possible in 82 patients. The X-rays and CT scans were proofed for loss of correction and fusion rate. The anterior column has been restored using a monocortical strut graft via a partial resection of the lamina and the apophyseal joint on one side to access the disc space. The dorsal reduction has been achieved using an angular stable pedicle screw system. The mean follow-up time was 15 months (range 8–39); 67 patients had a CT scan at follow-up and 83% showed a 360° fusion. The average post-operative loss of correction was 3.3° (range 0–21). The average duration of operation was 192 min (range 120–360) and the mean blood loss was 790 ml (range 300–3,400 ml). Regarding the complications we did not have any deep wound infections. We had two epidural haematomas postoperatively with a neurological deterioration that had to be revised. We were able to decompress the neurological structures and restore the weight-bearing capability of the anterior column in a one-stage procedure. So we think that this technique can be an alternative procedure to combined operations regarding the presented radiological results of successful fusion and loss of correction. PMID:20217152

The determination of psilocin and psilocybin in hallucinogenic mushrooms by HPLC utilizing a dual reagent acidic potassium permanganate and tris(2,2'-bipyridyl)ruthenium(II) chemiluminescence detection system.

PubMed

Anastos, Nicole; Lewis, Simon W; Barnett, Neil W; Sims, D Noel

2006-01-01

This paper describes a procedure for the determination of psilocin and psilocybin in mushroom extracts using high-performance liquid chromatography with postcolumn chemiluminescence detection. A number of extraction methods for psilocin and psilocybin in hallucinogenic mushrooms were investigated, with a simple methanolic extraction being found to be most effective. Psilocin and psilocybin were extracted from a variety of hallucinogenic mushrooms using methanol. The analytes were separated on a C12 column using a (95:5% v/v) methanol:10 mM ammonium formate, pH 3.5 mobile phase with a run time of 5 min. Detection was realized through a dual reagent chemiluminescence detection system of acidic potassium permanganate and tris(2,2'-bipyridyl)ruthenium(II). The chemiluminescence detection system gave improved detectability when compared with UV absorption at 269 nm, with detection limits of 1.2 x 10(-8) and 3.5 x 10(-9) mol/L being obtained for psilocin and psilocybin, respectively. The procedure was applied to the determination of psilocin and psilocybin in three Australian species of hallucinogenic mushroom.

Development of life prediction capabilities for liquid propellant rocket engines. Post-fire diagnostic system for the SSME system architecture study

NASA Technical Reports Server (NTRS)

Gage, Mark; Dehoff, Ronald

1991-01-01

This system architecture task (1) analyzed the current process used to make an assessment of engine and component health after each test or flight firing of an SSME, (2) developed an approach and a specific set of objectives and requirements for automated diagnostics during post fire health assessment, and (3) listed and described the software applications required to implement this system. The diagnostic system described is a distributed system with a database management system to store diagnostic information and test data, a CAE package for visual data analysis and preparation of plots of hot-fire data, a set of procedural applications for routine anomaly detection, and an expert system for the advanced anomaly detection and evaluation.

Combining UASB technology and advanced oxidation processes (AOPs) to treat food processing wastewaters.

PubMed

Sigge, G O; Britz, J; Fourie, P C; Barnardt, C A; Strydom, R

2002-01-01

UASB treatment of fruit cannery and winery effluents was shown to be feasible. However, the treated effluents still have residual COD levels well above the legal limit of 75 mg.l(-1) for direct discharge to a water system and a form of post-treatment is necessary to reduce the COD further. Ozone and ozone/hydrogen peroxide were used in combination with a granular activated carbon contacting column to assess the effectiveness as a post-treatment option for the UASB treated fruit cannery and winery effluent. Colour reduction in the effluents ranged from 66 to 90% and COD reductions of 27-55% were achieved. The combination of ozone and hydrogen peroxide gave better results than ozonation alone. Significant progress was thus made in achieving the legal limit of 75 mg.l(-1).

Forest Fire Advanced System Technology (FFAST): A Conceptual Design for Detection and Mapping

Treesearch

J. David Nichols; John R. Warren

1987-01-01

The Forest Fire Advanced System Technology (FFAST) project is developing a data system to provide near-real-time forest fire information to fire management at the fire Incident Command Post (ICP). The completed conceptual design defined an integrated forest fire detection and mapping system that is based upon technology available in the 1990's. System component...

[Isolation and determination of the seeds of Pachyrrhizus errosus protein by high performance gel filtration chromatography (GFC)].

PubMed

Wu, H; Hao, B; Tang, G; Lin, Y

1997-03-01

From the seeds of Pachyrrhizus errosus, three protein constituents, namel PE1, PE2 and PE3, have been isolated and purified by extraction with 5mmol/L phosphate saline (0.9% NaCl) buffer (PB) at pH 7.2, and S-Sepharose Fast Flow Column (2.6cm x 15cm) chromatography which eluted with 5mmol/L phosphate buffer (pH 7.0) containing 1mmol/L NaCl. Three proteins were burther separated on two connected Protein-Pak 60+Protein-Pak 125 [7.5mm x 39cm, 10microm] columns with mobile phase of 0.2mol/L phosphate buffer (pH 6.5). The flow rate was kept constant at 0.8mL/min by YSB-2 type high press pump. The effluent was monitored at a wavelength of 280nm on photodiode array detector. These three proteins are proved to be homogeneous by SDS-PAGE, IEF and HPGFC experiments, and all present the typical absorption spectra in ultraviolet region. The moleculer weights of the three proteins are approxiamtely 33000D, 14500D and 14000D respectively by SDS-PAGE. But as using HPGFC analysis, the MW value of PE2 is 28000D. This indicates PE2 may be composed of two chains joined by disulfide bond, which is further proved from the latter amino acid composition analysis. The isoelectric points of three proteins are 4.5, 6.5 and 7.5 respectively by using IEF. The amion acids compositions of the three proteins were determined with OPA post-column derivatization/fluorescence detection.

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

Liu, Ying

My graduate research has focused on separation science and bioanalytical analysis, which emphasized in method development. It includes three major areas: enantiomeric separations using high performance liquid chromatography (HPLC), Super/subcritical fluid chromatography (SFC), and capillary electrophoresis (CE); drug-protein binding behavior studies using CE; and carbohydrate analysis using liquid chromatograph-electrospray ionization mass spectrometry (LC-ESI-MS). Enantiomeric separations continue to be extremely important in the pharmaceutical industry. An in-depth evaluation of the enantiomeric separation capabilities of macrocyclic glycopeptides CSPs with SFC mobile phases was investigated using a set of over 100 chiral compounds. It was found that the macrocyclic based CSPs were ablemore » to separate enantiomers of various compounds with different polarities and functionalities. Seventy percent of all separations were achieved in less than 4 min due to the high flow rate (4.0 ml/min) that can be used in SFC. Drug-protein binding is an important process in determining the activity and fate of a drug once it enters the body. Two drug/protein systems have been studied using frontal analysis CE method. More sensitive fluorescence detection was introduced in this assay, which overcame the problem of low sensitivity that is common when using UV detection for drug-protein studies. In addition, the first usage of an argon ion laser with 257 nm beam coupled with CCD camera as a frontal analysis detection method enabled the simultaneous observation of drug fluorescence as well as the protein fluorescence. LC-ESI-MS was used for the separation and characterization of underivatized oligosaccharide mixtures. With the limits of detection as low as 50 picograms, all individual components of oligosaccharide mixtures (up to 11 glucose-units long) were baseline resolved on a Cyclobond I 2000 column and detected using ESI-MS. This system is characterized by high chromatographic resolution, high column stability, and high sensitivity. In addition, this method showed potential usefulness for the sensitive and quick analysis of hydrolysis products of polysaccharides, and for trace level analysis of individual oligosaccharides or oligosaccharide isomers from biological systems.« less

40 CFR 265.228 - Closure and post-closure care.

Code of Federal Regulations, 2010 CFR

2010-07-01

... detection system in accordance with §§ 264.221(c)(2)(iv) and (3) of this chapter and 265.226(b) and comply with all other applicable leak detection system requirements of this part; (3) Maintain and monitor the... or operator must: (1) Remove or decontaminate all waste residues, contaminated containment system...

Analyses via automated mass spectrometry (MS/DS)

NASA Technical Reports Server (NTRS)

Koenig, T.

1985-01-01

New or improved uses of the Finnigan 4000 quadrupole mass spectrometer (MS) with its associated INCOS data system (DS) were investigated. The first phase involved an evaluative activity in which specific problems with miscalibration and gas chromatographic column conditioning were identified. This also revealed one solution to the problem of detection of substances not visible in the gas chromatography detection mode. A second phase was to seek useful applications of the direct inlet systems. This mode of sample introduction has not been previously utilized on the existing equipment and was successfully applied to the analysis of the components of TONOX 60/40 and in the thermal degradation products of some polymeric materials. Suggestions are made for improving and expanding the use of the MS/DS system in materials development and testing.

Identification of Successive ``Unobservable'' Cyber Data Attacks in Power Systems Through Matrix Decomposition

NASA Astrophysics Data System (ADS)

Gao, Pengzhi; Wang, Meng; Chow, Joe H.; Ghiocel, Scott G.; Fardanesh, Bruce; Stefopoulos, George; Razanousky, Michael P.

2016-11-01

This paper presents a new framework of identifying a series of cyber data attacks on power system synchrophasor measurements. We focus on detecting "unobservable" cyber data attacks that cannot be detected by any existing method that purely relies on measurements received at one time instant. Leveraging the approximate low-rank property of phasor measurement unit (PMU) data, we formulate the identification problem of successive unobservable cyber attacks as a matrix decomposition problem of a low-rank matrix plus a transformed column-sparse matrix. We propose a convex-optimization-based method and provide its theoretical guarantee in the data identification. Numerical experiments on actual PMU data from the Central New York power system and synthetic data are conducted to verify the effectiveness of the proposed method.

Determination of flavonoids and saponins in Gynostemma pentaphyllum (Thunb.) Makino by liquid chromatography-mass spectrometry.

PubMed

Kao, T H; Huang, S C; Inbaraj, B Stephen; Chen, B H

2008-09-26

Gynostemma pentaphyllum (Thunb.) Makino, a traditional Chinese herb possessing antitumor and antioxidant activities, has been shown to contain several functional components like saponins and flavonoids. However, their identities remain uncertain. The objectives of this study were to develop an appropriate extraction, purification and HPLC-MS method to determine saponins and flavonoids in G. pentaphyllum. Both flavonoids and saponins were extracted with methanol, followed by purification with a C18 cartridge to elute the former with 50% methanol and the latter with 100% methanol. A total of 34 saponins were separated within 40 min by a Gemini C18 column and a gradient mobile phase of acetonitrile and 0.1% formic acid in water, in which 18 saponins were identified by LC-MS with ESI mode and Q-TOF (LC/MS/MS). Similarly, a total of eight flavonoids were separated within 45 min by the same column and a gradient solvent system of methanol and 0.1% formic acid in water, with identification being carried out by a post-column derivatization method and LC-MS with ESI mode. The amounts of flavonoids in G. pentaphyllum ranged from 170.7 to 2416.5 mug g(-1), whereas saponins were from 491.0 to 89,888.9 mug g(-1).

Floating treatment wetlands for domestic wastewater treatment.

PubMed

Faulwetter, J L; Burr, M D; Cunningham, A B; Stewart, F M; Camper, A K; Stein, O R

2011-01-01

Floating islands are a form of treatment wetland characterized by a mat of synthetic matrix at the water surface into which macrophytes can be planted and through which water passes. We evaluated two matrix materials for treating domestic wastewater, recycled plastic and recycled carpet fibers, for chemical oxygen demand (COD) and nitrogen removal. These materials were compared to pea gravel or open water (control). Experiments were conducted in laboratory scale columns fed with synthetic wastewater containing COD, organic and inorganic nitrogen, and mineral salts. Columns were unplanted, naturally inoculated, and operated in batch mode with continuous recirculation and aeration. COD was efficiently removed in all systems examined (>90% removal). Ammonia was efficiently removed by nitrification. Removal of total dissolved N was ∼50% by day 28, by which time most remaining nitrogen was present as NO(3)-N. Complete removal of NO(3)-N by denitrification was accomplished by dosing columns with molasses. Microbial communities of interest were visualized with denaturing gradient gel electrophoresis (DGGE) by targeting specific functional genes. Shifts in the denitrifying community were observed post-molasses addition, when nitrate levels decreased. The conditioning time for reliable nitrification was determined to be approximately three months. These results suggest that floating treatment wetlands are a viable alternative for domestic wastewater treatment.

Automated and sensitive method for the determination of formoterol in human plasma by high-performance liquid chromatography and electrochemical detection.

PubMed

Campestrini, J; Lecaillon, J B; Godbillon, J

1997-12-19

An automated high-performance liquid chromatography (HPLC) method for the determination of formoterol in human plasma with improved sensitivity has been developed and validated. Formoterol and CGP 47086, the internal standard, were extracted from plasma (1 ml) using a cation-exchange solid-phase extraction (SPE) cartridge. The compounds were eluted with pH 6 buffer solution-methanol (70:30, v/v) and the eluate was further diluted with water. An aliquot of the extract solution was injected and analyzed by HPLC. The extraction, dilution, injection and chromatographic analysis were combined and automated using the automate (ASPEC) system. The chromatographic separations were achieved on a 5 microm, Hypersil ODS analytical column (200 mm x 3 mm I.D.), using (pH 6 phosphate buffer, 0.035 M + 20 mg/l EDTA)-MeOH-CH3CN (70:25:5, v/v/v) as the mobile phase at a flow-rate of 0.4 ml/min. The analytes were detected with electrochemical detection at an operating potential of +0.63 V. Intra-day accuracy and precision were assessed from the relative recoveries of calibration/quality control plasma samples in the concentration range of 7.14 to 238 pmol/l of formoterol base. The accuracy over the entire concentration range varied from 81 to 105%, and the precision (C.V.) ranged from 3 to 14%. Inter-day accuracy and precision were assessed in the concentration range of 11.9 to 238 pmol/l of formoterol base in plasma. The accuracy over the entire concentration range varied from 98 to 109%, and precision ranged from 8 to 19%. At the limit of quantitation (LOQ) of 11.9 pmol/l for inter-day measurements, the recovery value was 109% and C.V. was 19%. As shown from intra-day accuracy and precision results, favorable conditions (a newly used column, a newly washed detector cell and moderate residual cell current level) allowed us to reach a LOQ of 7.14 pmol/l of formoterol base (3 pg/ml of formoterol fumarate dihydrate). Improvement of the limit of detection by a factor of about 10 was reached as compared to the previously described methods. The method has been applied for quantifying formoterol in plasma after 120 microg drug inhalation to volunteers. Formoterol was still measurable at 24 h post-dosing in most subjects and a slow elimination of formoterol from plasma beyond 6-8 h after inhalation was demonstrated for the first time thanks to the sensitivity of the method.

The Swift Burst Alert Telescope Detected Seyfert 1 Galaxies: X-Ray Broadband Properties and Warm Absorbers

NASA Technical Reports Server (NTRS)

Winter, Lisa M.; Veilleux, Sylvain; McKernan, Barry; Kallman, T.

2012-01-01

We present results from an analysis of the broadband, 0.3-195 keV, X-ray spectra of 48 Seyfert 1-1.5 sources detected in the very hard X-rays with the Swift Burst Alert Telescope (BAT). This sample is selected in an all-sky survey conducted in the 14-195 keV band. Therefore, our sources are largely unbiased toward both obscuration and host galaxy properties. Our detailed and uniform model fits to Suzaku/BAT and XMM-Newton/BAT spectra include the neutral absorption, direct power-law, reflected emission, soft excess, warm absorption, and narrow Fe I K[alpha] emission properties for the entire sample. We significantly detect O VII and O VIII edges in 52% of our sample. The strength of these detections is strongly correlated with the neutral column density measured in the spectrum. Among the strongest detections, X-ray grating and UV observations, where available, indicate outflowing material. The ionized column densities of sources with O VII and O VIII detections are clustered in a narrow range with Nwarm [approx] 1021 cm-2, while sources without strong detections have column densities of ionized gas an order of magnitude lower. Therefore, we note that sources without strong detections likely have warm ionized outflows present but at low column densities that are not easily probed with current X-ray observations. Sources with strong complex absorption have a strong soft excess, which may or may not be due to difficulties in modeling the complex spectra of these sources. Still, the detection of a flat [Gamma] [approx] 1 and a strong soft excess may allow us to infer the presence of strong absorption in low signal-to-noise active galactic nucleus spectra. Additionally, we include a useful correction from the Swift BAT luminosity to bolometric luminosity, based on a comparison of our spectral fitting results with published spectral energy distribution fits from 33 of our sources.

Effects of liquid post-column addition in electrospray ionization performance in supercritical fluid chromatography-mass spectrometry.

PubMed

Akbal, Laura; Hopfgartner, Gérard

2017-09-29

In supercritical fluid chromatography coupled to atmospheric pressure ionization mass spectrometry (SFC-MS), the use of a make-up post-column is almost mandatory to avoid analyte precipitation, especially when using low percentage of modifier (<5%) in the mobile phase. Due to the specific nature of gaseous CO 2 , the tuning of the make-up conditions in electrospray becomes an important factor and can be used to tune analyte sensitivity. Neither a dilution effect (loss of signal) nor a relevant degradation of chromatographic performances is observed with the addition of a make-up at various flow-rates, up to 0.7mL/min. From supercritical conditions (1mL/min 40°C, 150bar) to gaseous state (room temperature, atmospheric pressure), the CO 2 expands around 430 times, contributing to almost 5% of the nebulizing process. In positive mode, the presence of ammonium ions either in the mobile phase or in the make-up did significantly increase the MS signal, even at basic apparent pH. The ionization performance of electrospray is influenced by the acidic buffer power of the carbon dioxide, and was found to be restricted in the apparent pH range of 3.8-7.2 in the various conditions investigated. This may challenge sensitive detection in negative mode, as illustrated for bosentan. The use of DMSO as make-up additive (up to 30%) showed a simplification of the full scan spectrum regarding the adducts. Finally, the optimization of make-up composition leads to an enhancement up to a factor of 69 on the electrospray MS response signal, for the SFC-SRM/MS analysis of HIV protease inhibitors in plasma extracted from Dried Plasma Spots. Copyright © 2017 Elsevier B.V. All rights reserved.

Instant Integrated Ultradeep Quantitative-structural Membrane Proteomics Discovered Post-translational Modification Signatures for Human Cys-loop Receptor Subunit Bias.

PubMed

Zhang, Xi

2016-12-01

Neurotransmitter ligand-gated ion channels (LGICs) are widespread and pivotal in brain functions. Unveiling their structure-function mechanisms is crucial to drive drug discovery, and demands robust proteomic quantitation of expression, post-translational modifications (PTMs) and dynamic structures. Yet unbiased digestion of these modified transmembrane proteins-at high efficiency and peptide reproducibility-poses the obstacle. Targeting both enzyme-substrate contacts and PTMs for peptide formation and detection, we devised flow-and-detergent-facilitated protease and de-PTM digestions for deep sequencing (FDD) method that combined omni-compatible detergent, tandem immobilized protease/PNGase columns, and Cys-selective reduction/alkylation, to achieve streamlined ultradeep peptide preparation within minutes not days, at high peptide reproducibility and low abundance-bias. FDD transformed enzyme-protein contacts into equal catalytic travel paths through enzyme-excessive columns regardless of protein abundance, removed products instantly preventing inhibition, tackled intricate structures via sequential multiple micro-digestions along the flow, and precisely controlled peptide formation by flow rate. Peptide-stage reactions reduced steric bias; low contamination deepened MS/MS scan; distinguishing disulfide from M oxidation and avoiding gain/loss artifacts unmasked protein-endogenous oxidation states. Using a recent interactome of 285-kDa human GABA type A receptor, this pilot study validated FDD platform's applicability to deep sequencing (up to 99% coverage), H/D-exchange and TMT-based structural mapping. FDD discovered novel subunit-specific PTM signatures, including unusual nontop-surface N-glycosylations, that may drive subunit biases in human Cys-loop LGIC assembly and pharmacology, by redefining subunit/ligand interfaces and connecting function domains. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Simultaneous determination of gallic acid and gentisic acid in organic anion transporter expressing cells by liquid chromatography-tandem mass spectrometry.

PubMed

Wang, Li; Halquist, Matthew S; Sweet, Douglas H

2013-10-15

In order to elucidate the role of organic anion transporters (OATs) in the renal elimination of gallic acid and gentisic acid, a new, rapid, and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the simultaneous determination of gallic acid and gentisic acid in cell lysate, using Danshensu as the internal standard (IS). After a simple liquid-liquid extraction, the analytes were detected in negative ESI mode using selected reaction monitoring. The precursor-to-product ion transitions (m/z) were 169.0→125.0, 153.1→108.0, and 196.8→135.2 for gallic acid, gentisic acid, and the IS, respectively. Chromatographic separation was achieved on a C18 column using mobile phases consisting of water with 0.1% acetic acid (A) and acetonitrile with 0.05% formic acid. (B) The total run time was 3min and calibration curves were linear over the concentrations of 0.33-2400ng/mL for both compounds (r(2)>0.995). Good precision (between 3.11% and 14.1% RSD) and accuracy (between -12.7% and 11% bias) was observed for quality controls at concentrations of 0.33 (lower limit of quantification), 1, 50, and 2000ng/mL. The mean extraction recovery of gallic acid and gentisic acid was 80.7% and 83.5%, respectively. Results from post-column infusion and post-extraction methods indicated that the analytical method exhibited negligible matrix effects. Finally, this validated assay was successfully applied in a cellular uptake study to determine the intracellular concentrations of gallic acid and gentisic acid in OAT expressing cells. Copyright © 2013 Elsevier B.V. All rights reserved.

Liquid chromatographic-tandem mass spectrometric method for the simultaneous determination of alkylphenols polyethoxylates, alkylphenoxy carboxylates and alkylphenols in wastewater and surface-water.

PubMed

Ciofi, L; Ancillotti, C; Chiuminatto, U; Fibbi, D; Checchini, L; Orlandini, S; Del Bubba, M

2014-10-03

Four different pellicular stationary phases (i.e. octadecylsilane, octasilane, Phenyl-Hexyl and pentafluorophenyl) were investigated for the chromatographic resolution of alkylphenols (APs), alkylphenols polyethoxylates (APnEOs) and alkylphenoxy carboxylates (APECs) using mixtures of water and organic solvents (i.e. methanol, acetonitrile and tetrahydrofuran) as eluents, in order to obtain their determination by a single LC-MS/MS run. In fact, alkylphenols and alkylphenoxy carboxylates must be analysed in negative ion mode, whereas alkylphenols polyethoxylates undergo ionisation only in positive ion mode, and therefore, two distinct LC-MS/MS analysis are commonly adopted. The best resolution among the aforementioned target analytes was achieved on the pentafluorophenyl column, eluting with an acidified water-acetonitrile-tetrahydrofuran mixture and using the post column addition of an ammonia solution in methanol for the detection of positively ionisable compounds. Under these optimized chromatographic conditions the investigated compounds were determined via a single chromatographic run, with only one polarity switch, in 15min, achieving the following instrumental detection limits: 600pg for AP1EOs, 0.8-14pg for AP2EOs, 10.4-150pg for APs and 4.4-4.8pg for APECs. The chromatographic method was coupled with solid-phase extraction and clean-up procedures and successfully applied to the analysis of wastewater and surface water samples, highlighting mean concentration ranging from 6ng/L for 4-t-OP1EC to 1434ng/L for 4-NP1121EC, depending on the sample analysed. Copyright © 2014 Elsevier B.V. All rights reserved.

The aquatic fate of triclopyr in whole-pond treatments

USGS Publications Warehouse

Petty, D.G.; Skogerboe, J.G.; Getsinger, K.D.; Foster, D.R.; Houtman, B.A.; Fairchild, J.F.; Anderson, L.W.

2001-01-01

The aquatic fate of the triethylamine salt formulation of triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid) was determined in whole-pond applications in closed (no water exchange) systems in California, Missouri and Texas in two studies conducted in 1995 and 1996. These studies determined dissipation rates of triclopyr and its principal metabolites, 3,5,6-trichloropyridinol (tcp) and 3,5,6-trichloro-2-methoxypyridine (tmp) in water, sediment and finfish. Ponds at each site containing a healthy biological community were treated at 2.5 mg AE litre-1 triclopyr. Water and sediment samples were collected through 12 weeks post-treatment, and non-target animals were collected through 4 weeks post-treatment. Dissipation rates for triclopyr, TCP and TMP were similar at each of the study sites, despite differences in weather, water quality, biotic community, light transmission and geographic location. Half-lives of triclopyr in water ranged from 5.9 to 7.5 days, while those of TCP and TMP ranged from 4 to 8.8 and 4 to 10 days, respectively. Levels of triclopyr and TCP declined in sediments at half-lives ranging from 2.8 to 4.6 days and 3.8 to 13.3 days, respectively. No TMP was detected in sediment. Triclopyr and TCP cleared from fish in relation to concentrations found in the water column. TMP levels in fish were generally an order of magnitude higher than levels of triclopyr and TCP, particularly in the visceral portion of the animals. No adverse effects on water quality or on the non-target biotic community were found following triclopyr applications. Results of these studies were comparable to those of triclopyr dissipation studies conducted in reservoirs, lakes and riverine systems in Georgia, Florida, Minnesota and Washington, indicating that the degradation and dissipation of triclopyr and its metabolites are similar in representative systems throughout the USA. ?? 2001 Society of Chemical Industry.

Development and Validation of a Method for Alcohol Analysis in Brain Tissue by Headspace Gas Chromatography with Flame Ionization Detector

PubMed Central

Chun, Hao-Jung; Poklis, Justin L.; Poklis, Alphonse; Wolf, Carl E.

2016-01-01

Ethanol is the most widely used and abused drug. While blood is the preferred specimen for analysis, tissue specimens such as brain serve as alternative specimens for alcohol analysis in post-mortem cases where blood is unavailable or contaminated. A method was developed using headspace gas chromatography with flame ionization detection (HS-GC-FID) for the detection and quantification of ethanol, acetone, isopropanol, methanol and n-propanol in brain tissue specimens. Unfixed volatile-free brain tissue specimens were obtained from the Department of Pathology at Virginia Commonwealth University. Calibrators and controls were prepared from 4-fold diluted homogenates of these brain tissue specimens, and were analyzed using t-butanol as the internal standard. The chromatographic separation was performed with a Restek BAC2 column. A linear calibration was generated for all analytes (mean r2 > 0.9992) with the limits of detection and quantification of 100–110 mg/kg. Matrix effect from the brain tissue was determined by comparing the slopes of matrix prepared calibration curves with those of aqueous calibration curves; no significant differences were observed for ethanol, acetone, isopropanol, methanol and n-propanol. The bias and the CVs for all volatile controls were ≤10%. The method was also evaluated for carryover, selectivity, interferences, bench-top stability and freeze-thaw stability. The HS-GC-FID method was determined to be reliable and robust for the analysis of ethanol, acetone, isopropanol, methanol and n-propanol concentrations in brain tissue, effectively expanding the specimen options for post-mortem alcohol analysis. PMID:27488829

Proteome-wide detection and quantitative analysis of irreversible cysteine oxidation using long column UPLC-pSRM.

PubMed

Lee, Chia-Fang; Paull, Tanya T; Person, Maria D

2013-10-04

Reactive oxygen species (ROS) play an important role in normal biological functions and pathological processes. ROS is one of the driving forces for oxidizing proteins, especially on cysteine thiols. The labile, transient, and dynamic nature of oxidative modifications poses enormous technical challenges for both accurate modification site determination and quantitation of cysteine thiols. The present study describes a mass spectrometry-based approach that allows effective discovery and quantification of irreversible cysteine modifications. The utilization of a long reverse phase column provides high-resolution chromatography to separate different forms of modified cysteine thiols from protein complexes or cell lysates. This Fourier transform mass spectrometry (FT-MS) approach enabled detection and quantitation of ataxia telangiectasia mutated (ATM) complex cysteine sulfoxidation states using Skyline MS1 filtering. When we applied the long column ultra high pressure liquid chromatography (UPLC)-MS/MS analysis, 61 and 44 peptides from cell lysates and cells were identified with cysteine modifications in response to in vitro and in vivo H2O2 oxidation, respectively. Long column ultra high pressure liquid chromatography pseudo selected reaction monitoring (UPLC-pSRM) was then developed to monitor the oxidative level of cysteine thiols in cell lysate under varying concentrations of H2O2 treatment. From UPLC-pSRM analysis, the dynamic conversion of sulfinic (S-O2H) and sulfonic acid (S-O3H) was observed within nucleoside diphosphate kinase (Nm23-H1) and heat shock 70 kDa protein 8 (Hsc70). These methods are suitable for proteome-wide studies, providing a highly sensitive, straightforward approach to identify proteins containing redox-sensitive cysteine thiols in biological systems.

Advances in High Energy Solid-State Pulsed 2-Micron Lidar Development for Ground and Airborne Wind, Water Vapor and CO2 Measurements

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Kavaya, Michael J.; Remus, Ruben

2015-01-01

NASA Langley Research Center has a long history of developing 2-micron lasers. From fundamental spectroscopy research, theoretical prediction of new materials, laser demonstration and engineering of lidar systems, it has been a very successful program spanning around two decades. Successful development of 2-micron lasers has led to development of a state-of-the-art compact lidar transceiver for a pulsed coherent Doppler lidar system for wind measurement with an unprecedented laser pulse energy of 250 millijoules in a rugged package. This high pulse energy is produced by a Ho:Tm:LuLiF laser with an optical amplifier. While the lidar is meant for use as an airborne instrument, ground-based tests were carried out to characterize performance of the lidar. Atmospheric measurements will be presented, showing the lidar's capability for wind measurement in the atmospheric boundary layer and free troposphere. Lidar wind measurements are compared to a balloon sonde, showing good agreement between the two sensors. Similar architecture has been used to develop a high energy, Ho:Tm:YLF double-pulsed 2-micron Integrated Differential Absorption Lidar (IPDA) instrument based on direct detection technique that provides atmospheric column CO2 measurements. This instrument has been successfully used to measure atmospheric CO2 column density initially from a ground mobile lidar trailer, and then it was integrated on B-200 plane and 20 hours of flight measurement were made from an altitude ranging 1500 meters to 8000 meters. These measurements were compared to in-situ measurements and National Oceanic and Atmospheric Administration (NOAA) airborne flask measurement to derive the dry mixing ratio of the column CO2 by reflecting the signal by various reflecting surfaces such as land, vegetation, ocean surface, snow and sand. The lidar measurements when compared showed a very agreement with in-situ and airborne flask measurement. NASA Langley Research Center is currently developing a triple-pulsed 2-micron Integrated Differential Absorption Lidar (IPDA) instrument for simultaneous measurement of water vapor and carbon-dioxide column density measurement from an air-borne platform. This presentation will give an overview of the 2 decades of 2-micron coherent and direction detection of laser/lidar development at NASA Langley Research Center and will present the ground and airborne wind and column CO2 measurement intercomparison with in-situ, balloon and flask measurements.

Observations of Al, Fe and Ca(+) in Mercury's Exosphere

NASA Technical Reports Server (NTRS)

Bida, Thomas A.; Killen, Rosemary M.

2011-01-01

We report 5-(sigma) tangent column detections of Al and Fe, and strict 3-(sigma) tangent column upper limits for Ca(+) in Mercury's exosphere obtained using the HIRES spectrometer on the Keck I telescope. These are the first direct detections of Al and Fe in Mercury's exosphere. Our Ca(-) observation is consistent with that reported by The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft.

Approach for ochratoxin A fast screening in spices using clean-up tandem immunoassay columns with confirmation by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS).

PubMed

Goryacheva, I Yu; De Saeger, S; Lobeau, M; Eremin, S A; Barna-Vetró, I; Van Peteghem, C

2006-09-01

An approach for ochratoxin A (OTA) fast cost-effective screening based on clean-up tandem immunoassay columns was developed and optimized for OTA detection with a cut-off level of 10 microg kg(-1) in spices. Two procedures were tested and applied for OTA detection. Column with bottom detection immunolayer was optimized for OTA determination in Capsicum ssp. spices. A modified clean-up tandem immunoassay procedure with top detection immunolayer was successfully applied for all tested spices. Its main advantages were decreasing of the number of analysis steps and quantity of antibody and also minimizing of matrix effects. The total duration of the extraction and analysis was about 40 min for six samples. Chilli, red pepper, pili-pili, cayenne, paprika, nutmeg, ginger, white pepper and black pepper samples were analyzed for OTA contamination by the proposed clean-up tandem immunoassay procedures. Clean-up tandem immunoassay results were confirmed by HPLC-MS/MS with immunoaffinity column clean-up. Among 17 tested Capsicum ssp. spices, 6 samples (35%) contained OTA in a concentration exceeding the 10 microg kg(-1) limit discussed by the European Commission. All tested nutmeg (n=8), ginger (n=5), white pepper (n=7) and black pepper (n=6) samples did not contain OTA above this action level.

Systematic evaluation of commercially available ultra-high performance liquid chromatography columns for drug metabolite profiling: optimization of chromatographic peak capacity.

PubMed

Dubbelman, Anne-Charlotte; Cuyckens, Filip; Dillen, Lieve; Gross, Gerhard; Hankemeier, Thomas; Vreeken, Rob J

2014-12-29

The present study investigated the practical use of modern ultra-high performance liquid chromatography (UHPLC) separation techniques for drug metabolite profiling, aiming to develop a widely applicable, high-throughput, easy-to-use chromatographic method, with a high chromatographic resolution to accommodate simultaneous qualitative and quantitative analysis of small-molecule drugs and metabolites in biological matrices. To this end, first the UHPLC system volume and variance were evaluated. Then, a mixture of 17 drugs and various metabolites (molecular mass of 151-749Da, logP of -1.04 to 6.7), was injected on six sub-2μm particle columns. Five newest generation core shell technology columns were compared and tested against one column packed with porous particles. Two aqueous (pH 2.7 and 6.8) and two organic mobile phases were evaluated, first with the same flow and temperature and subsequently at each column's individual limit of temperature and pressure. The results demonstrated that pre-column dead volume had negligible influence on the peak capacity and shape. In contrast, a decrease in post-column volume of 57% resulted in a substantial (47%) increase in median peak capacity and significantly improved peak shape. When the various combinations of stationary and mobile phases were used at the same flow rate (0.5mL/min) and temperature (45°C), limited differences were observed between the median peak capacities, with a maximum of 26%. At higher flow though (up to 0.9mL/min), a maximum difference of almost 40% in median peak capacity was found between columns. The finally selected combination of solid-core particle column and mobile phase composition was chosen for its selectivity, peak capacity, wide applicability and peak shape. The developed method was applied to rat hepatocyte samples incubated with the drug buspirone and demonstrated to provide a similar chromatographic resolution, but a 6 times higher signal-to-noise ratio than a more traditional UHPLC metabolite profiling method using a fully porous particle packed column, within one third of the analysis time. In conclusion, a widely applicable, selective and fast chromatographic method was developed that can be applied to perform drug metabolite profiling in the timeframe of a quantitative analysis. It is envisioned that this method will in future be used for simultaneous qualitative and quantitative analysis and can therefore be considered a first important step in the Quan/Qual workflow. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of dissolved bromate in drinking water by ion chromatography and post column reaction: interlaboratory study.

PubMed

Cordeiro, Fernando; Robouch, Piotr; de la Calle, Maria Beatriz; Emteborg, Håkan; Charoud-Got, Jean; Schmitz, Franz

2011-01-01

A collaborative study, International Evaluation Measurement Programme-25a, was conducted in accordance with international protocols to determine the performance characteristics of an analytical method for the determination of dissolved bromate in drinking water. The method should fulfill the analytical requirements of Council Directive 98/83/EC (referred to in this work as the Drinking Water Directive; DWD). The new draft standard method under investigation is based on ion chromatography followed by post-column reaction and UV detection. The collaborating laboratories used the Draft International Organization for Standardization (ISO)/Draft International Standard (DIS) 11206 document. The existing standard method (ISO 15061:2001) is based on ion chromatography using suppressed conductivity detection, in which a preconcentration step may be required for the determination of bromate concentrations as low as 3 to 5 microg/L. The new method includes a dilution step that reduces the matrix effects, thus allowing the determination of bromate concentrations down to 0.5 microg/L. Furthermore, the method aims to minimize any potential interference of chlorite ions. The collaborative study investigated different types of drinking water, such as soft, hard, and mineral water. Other types of water, such as raw water (untreated), swimming pool water, a blank (named river water), and a bromate standard solution, were included as test samples. All test matrixes except the swimming pool water were spiked with high-purity potassium bromate to obtain bromate concentrations ranging from 1.67 to 10.0 microg/L. Swimming pool water was not spiked, as this water was incurred with bromate. Test samples were dispatched to 17 laboratories from nine different countries. Sixteen participants reported results. The repeatability RSD (RSD(r)) ranged from 1.2 to 4.1%, while the reproducibility RSD (RSDR) ranged from 2.3 to 5.9%. These precision characteristics compare favorably with those of ISO 15601. A thorough comparison of the performance characteristics is presented in this report. All method performance characteristics obtained in the frame of this collaborative study indicate that the draft ISO/DIS 11206 standard method meets the requirements set down by the DWD. It can, therefore, be considered to fit its intended analytical purpose.

NASA GPM GV Science Implementation

NASA Technical Reports Server (NTRS)

Petersen, W. A.

2009-01-01

Pre-launch algorithm development & post-launch product evaluation: The GPM GV paradigm moves beyond traditional direct validation/comparison activities by incorporating improved algorithm physics & model applications (end-to-end validation) in the validation process. Three approaches: 1) National Network (surface): Operational networks to identify and resolve first order discrepancies (e.g., bias) between satellite and ground-based precipitation estimates. 2) Physical Process (vertical column): Cloud system and microphysical studies geared toward testing and refinement of physically-based retrieval algorithms. 3) Integrated (4-dimensional): Integration of satellite precipitation products into coupled prediction models to evaluate strengths/limitations of satellite precipitation producers.

Detection and Estimation of 2-D Distributions of Greenhouse Gas Source Concentrations and Emissions over Complex Urban Environments and Industrial Sites

NASA Astrophysics Data System (ADS)

Zaccheo, T. S.; Pernini, T.; Dobler, J. T.; Blume, N.; Braun, M.

2017-12-01

This work highlights the use of the greenhouse-gas laser imaging tomography experiment (GreenLITETM) data in conjunction with a sparse tomography approach to identify and quantify both urban and industrial sources of CO2 and CH4. The GreenLITETM system provides a user-defined set of time-sequenced intersecting chords or integrated column measurements at a fixed height through a quasi-horizontal plane of interest. This plane, with unobstructed views along the lines of sight, may range from complex industrial facilities to a small city scale or urban sector. The continuous time phased absorption measurements are converted to column concentrations and combined with a plume based model to estimate the 2-D distribution of gas concentration over extended areas ranging from 0.04-25 km2. Finally, these 2-D maps of concentration are combined with ancillary meteorological and atmospheric data to identify potential emission sources and provide first order estimates of their associated fluxes. In this presentation, we will provide a brief overview of the systems and results from both controlled release experiments and a long-term system deployment in Paris, FR. These results provide a quantitative assessment of the system's ability to detect and estimate CO2 and CH4 sources, and demonstrate its ability to perform long-term autonomous monitoring and quantification of either persistent or sporadic emissions that may have both health and safety as well as environmental impacts.

Determination of erythromycin in human plasma, using column liquid chromatography with a polymeric packing material, alkaline mobile phase and amperometric detection.

PubMed

Nilsson, L G; Walldorf, B; Paulsen, O

1987-12-25

A method based on column liquid chromatography was developed for determination of plasma concentrations of erythromycin. PRP-1, a polymeric type of packing material suitable for chromatography and amperometric detection at high pH, was used. The effect of pH on the column performance and on the electrochemical response was studied. A pH of ca. 10 was found to be optimal. After extraction with tert.-butyl methyl ether, plasma concentrations down to 0.2 mumol/l could be measured, using automated sample injection. Oleandomycin was used as internal standard. The method was used for determination of plasma concentrations in a pharmacokinetic study under steady-state conditions.

Biological conversion system

DOEpatents

Scott, C.D.

A system for bioconversion of organic material comprises a primary bioreactor column wherein a biological active agent (zymomonas mobilis) converts the organic material (sugar) to a product (alcohol), a rejuvenator column wherein the biological activity of said biological active agent is enhanced, and means for circulating said biological active agent between said primary bioreactor column and said rejuvenator column.

Determination of cocaine and metabolites in hair by column-switching LC-MS-MS analysis.

PubMed

Alves, Marcela Nogueira Rabelo; Zanchetti, Gabriele; Piccinotti, Alberto; Tameni, Silvia; De Martinis, Bruno Spinosa; Polettini, Aldo

2013-07-01

A method for rapid, selective, and robust determination of cocaine (CO) and metabolites in 5-mg hair samples was developed and fully validated using a column-switching liquid chromatography-tandem mass spectrometry system (LC-MS-MS). Hair samples were decontaminated, segmented, incubated overnight in diluted HCl, and centrifuged, and the diluted (1:10 with distilled water) extracts were analyzed in positive ionization mode monitoring two reactions per analyte. Quantifier transitions were: m/z 304.2→182.2 for CO, m/z 290.1→168.1 for benzoylecgonine (BE), and m/z 318.2→196.2 for cocaethylene (CE). The lower limit of quantification (LLOQ) was set at 0.05 ng/mg for CO and CE, and 0.012 ng/mg for BE. Imprecision and inaccuracy at LLOQ were lower than 20 % for all analytes. Linearity ranged between 0.05 and 50.0 ng/mg for CO and CE and 0.012 and 12.50 ng/mg for BE. Selectivity, matrix effect, process efficiency, recovery, carryover, cross talk, and autosampler stability were also evaluated during validation. Eighteen real hair samples and five samples from a commercial proficiency testing program were comparatively examined with the proposed multidimensional chromatography coupled with tandem mass spectrometry procedure and our reference gas chromatography coupled to mass spectrometry (GC-MS) method. Compared with our reference GC-MS method, column-switching technique and the high sensitivity of the tandem mass spectrometry detection system allowed to significantly reduce sample amount (×10) with increased sensitivity (×2) and sample throughput (×4), to simplify sample preparation, and to avoid that interfering compounds and ions impaired the ionization and detection of the analytes and deteriorate the performance of the ion source.

In situ quantitative characterisation of the ocean water column using acoustic multibeam backscatter data

NASA Astrophysics Data System (ADS)

Lamarche, G.; Le Gonidec, Y.; Lucieer, V.; Lurton, X.; Greinert, J.; Dupré, S.; Nau, A.; Heffron, E.; Roche, M.; Ladroit, Y.; Urban, P.

2017-12-01

Detecting liquid, solid or gaseous features in the ocean is generating considerable interest in the geoscience community, because of their potentially high economic values (oil & gas, mining), their significance for environmental management (oil/gas leakage, biodiversity mapping, greenhouse gas monitoring) as well as their potential cultural and traditional values (food, freshwater). Enhancing people's capability to quantify and manage the natural capital present in the ocean water goes hand in hand with the development of marine acoustic technology, as marine echosounders provide the most reliable and technologically advanced means to develop quantitative studies of water column backscatter data. This is not developed to its full capability because (i) of the complexity of the physics involved in relation to the constantly changing marine environment, and (ii) the rapid technological evolution of high resolution multibeam echosounder (MBES) water-column imaging systems. The Water Column Imaging Working Group is working on a series of multibeam echosounder (MBES) water column datasets acquired in a variety of environments, using a range of frequencies, and imaging a number of water-column features such as gas seeps, oil leaks, suspended particulate matter, vegetation and freshwater springs. Access to data from different acoustic frequencies and ocean dynamics enables us to discuss and test multifrequency approaches which is the most promising means to develop a quantitative analysis of the physical properties of acoustic scatterers, providing rigorous cross calibration of the acoustic devices. In addition, high redundancy of multibeam data, such as is available for some datasets, will allow us to develop data processing techniques, leading to quantitative estimates of water column gas seeps. Each of the datasets has supporting ground-truthing data (underwater videos and photos, physical oceanography measurements) which provide information on the origin and chemistry of the seep content. This is of first importance when assessing the physical properties of water column scatterers from backscatter acoustic measurement.

Transient changes in bacterioplankton communities induced by the submarine volcanic eruption of El Hierro (Canary Islands).

PubMed

Ferrera, Isabel; Arístegui, Javier; González, José M; Montero, María F; Fraile-Nuez, Eugenio; Gasol, Josep M

2015-01-01

The submarine volcanic eruption occurring near El Hierro (Canary Islands) in October 2011 provided a unique opportunity to determine the effects of such events on the microbial populations of the surrounding waters. The birth of a new underwater volcano produced a large plume of vent material detectable from space that led to abrupt changes in the physical-chemical properties of the water column. We combined flow cytometry and 454-pyrosequencing of 16S rRNA gene amplicons (V1-V3 regions for Bacteria and V3-V5 for Archaea) to monitor the area around the volcano through the eruptive and post-eruptive phases (November 2011 to April 2012). Flow cytometric analyses revealed higher abundance and relative activity (expressed as a percentage of high-nucleic acid content cells) of heterotrophic prokaryotes during the eruptive process as compared to post-eruptive stages. Changes observed in populations detectable by flow cytometry were more evident at depths closer to the volcano (~70-200 m), coinciding also with oxygen depletion. Alpha-diversity analyses revealed that species richness (Chao1 index) decreased during the eruptive phase; however, no dramatic changes in community composition were observed. The most abundant taxa during the eruptive phase were similar to those in the post-eruptive stages and to those typically prevalent in oceanic bacterioplankton communities (i.e. the alphaproteobacterial SAR11 group, the Flavobacteriia class of the Bacteroidetes and certain groups of Gammaproteobacteria). Yet, although at low abundance, we also detected the presence of taxa not typically found in bacterioplankton communities such as the Epsilonproteobacteria and members of the candidate division ZB3, particularly during the eruptive stage. These groups are often associated with deep-sea hydrothermal vents or sulfur-rich springs. Both cytometric and sequence analyses showed that once the eruption ceased, evidences of the volcano-induced changes were no longer observed.

Transient Changes in Bacterioplankton Communities Induced by the Submarine Volcanic Eruption of El Hierro (Canary Islands)

PubMed Central

Ferrera, Isabel; Arístegui, Javier; González, José M.; Montero, María F.; Fraile-Nuez, Eugenio; Gasol, Josep M.

2015-01-01

The submarine volcanic eruption occurring near El Hierro (Canary Islands) in October 2011 provided a unique opportunity to determine the effects of such events on the microbial populations of the surrounding waters. The birth of a new underwater volcano produced a large plume of vent material detectable from space that led to abrupt changes in the physical-chemical properties of the water column. We combined flow cytometry and 454-pyrosequencing of 16S rRNA gene amplicons (V1–V3 regions for Bacteria and V3–V5 for Archaea) to monitor the area around the volcano through the eruptive and post-eruptive phases (November 2011 to April 2012). Flow cytometric analyses revealed higher abundance and relative activity (expressed as a percentage of high-nucleic acid content cells) of heterotrophic prokaryotes during the eruptive process as compared to post-eruptive stages. Changes observed in populations detectable by flow cytometry were more evident at depths closer to the volcano (~70–200 m), coinciding also with oxygen depletion. Alpha-diversity analyses revealed that species richness (Chao1 index) decreased during the eruptive phase; however, no dramatic changes in community composition were observed. The most abundant taxa during the eruptive phase were similar to those in the post-eruptive stages and to those typically prevalent in oceanic bacterioplankton communities (i.e. the alphaproteobacterial SAR11 group, the Flavobacteriia class of the Bacteroidetes and certain groups of Gammaproteobacteria). Yet, although at low abundance, we also detected the presence of taxa not typically found in bacterioplankton communities such as the Epsilonproteobacteria and members of the candidate division ZB3, particularly during the eruptive stage. These groups are often associated with deep-sea hydrothermal vents or sulfur-rich springs. Both cytometric and sequence analyses showed that once the eruption ceased, evidences of the volcano-induced changes were no longer observed. PMID:25671714

Fluorescence quenching as an indirect detection method for nitrated explosives.

PubMed

Goodpaster, J V; McGuffin, V L

2001-05-01

A novel approach based on fluorescence quenching is presented for the analysis of nitrated explosives. Seventeen common explosives and their degradation products are shown to be potent quenchers of pyrene, having Stern-Volmer constants that generally increase with the degree of nitration. Aromatic explosives such as 2,4,6-trinitrotoluene (2,4,6-TNT) are more effective quenchers than aliphatic or nitramine explosives. In addition, nitroaromatic explosives are found to have unique interactions with pyrene that lead to a wavelength dependence of their Stern-Volmer constants. This phenomenon allows for their differentiation from other nitrated explosives. The fluorescence quenching method is then applied to the determination of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazine(HMX), 2,4,6-TNT, nitromethane, and ammonium nitrate in various commercial explosive samples. The samples are separated by capillary liquid chromatography with post-column addition of the pyrene solution and detection by laser-induced fluorescence. The indirect fluorescence quenching method shows increased sensitivity and selectivity over traditional UV-visible absorbance as well as the ability to detect a wider range of organic and inorganic nitrated compounds.

Blood detection in the spinal column of whole cooked chicken using an optical fibre based sensor system

NASA Astrophysics Data System (ADS)

Sheridan, C.; O'Farrell, M.; Lyons, W. B.; Lewis, E.; Flanagan, C.; Jackman, N.

2005-01-01

An optical fibre based sensor has been developed to aid the quality assurance of food cooked in industrial ovens by monitoring the product in situ as it cooks. The sensor measures the product colour as it cooks by examining the reflected visible light from the surface as well as the core of the product. This paper examines the use of the sensor for the detection of blood in the spinal area of cooked whole chickens. The results presented here show that the sensor can be successfully used for this purpose.

Use of on-line supercritical fluid extraction-supercritical fluid chromatography/tandem mass spectrometry to analyze disease biomarkers in dried serum spots compared with serum analysis using liquid chromatography/tandem mass spectrometry.

PubMed

Suzuki, Makoto; Nishiumi, Shin; Kobayashi, Takashi; Sakai, Arata; Iwata, Yosuke; Uchikata, Takato; Izumi, Yoshihiro; Azuma, Takeshi; Bamba, Takeshi; Yoshida, Masaru

2017-05-30

The analytical stability and throughput of biomarker assays based on dried serum spots (DSS) are strongly dependent on the extraction process and determination method. In the present study, an on-line system based on supercritical fluid extraction-supercritical fluid chromatography coupled with tandem mass spectrometry (SFE-SFC/MS/MS) was established for analyzing the levels of disease biomarkers in DSS. The chromatographic conditions were investigated using the ODS-EP, diol, and SIL-100A columns. Then, we optimized the SFE-SFC/MS/MS method using the diol column, focusing on candidate biomarkers of oral, colorectal, and pancreatic cancer that were identified using liquid chromatography (LC)/MS/MS. By using this system, four hydrophilic metabolites and 17 hydrophobic metabolites were simultaneously detected within 15 min. In an experiment involving clinical samples, PC 16:0-18:2/16:1-18:1 exhibited 93.8% sensitivity and 64.3% specificity, whereas PC 17:1-18:1/17:0-18:2 showed 81.3% sensitivity and 92.9% specificity for detecting oral cancer. In addition, assessments of the creatine levels demonstrated 92.3% sensitivity and 78.6% specificity for detecting colorectal cancer. The results of this study indicate that our method has great potential for clinical diagnosis and would be suitable for large-scale screening. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Total 25-Hydroxyvitamin D Determination by an Entry Level Triple Quadrupole Instrument: Comparison between Two Commercial Kits

PubMed Central

Cocci, Andrea; Zuppi, Cecilia; Persichilli, Silvia

2013-01-01

Objective. 25-hydroxyvitamin D2/D3 (25-OHD2/D3) determination is a reliable biomarker for vitamin D status. Liquid chromatography-tandem mass spectrometry was recently proposed as a reference method for vitamin D status evaluation. The aim of this work is to compare two commercial kits (Chromsystems and PerkinElmer) for 25-OHD2/D3 determination by our entry level LC-MS/MS. Design and Methods. Chromsystems kit adds an online trap column to an HPLC column and provides atmospheric pressure chemical ionization, isotopically labeled internal standard, and 4 calibrator points. PerkinElmer kit uses a solvent extraction and protein precipitation method. This kit can be used with or without derivatization with, respectively, electrospray and atmospheric pressure chemical ionization. For each analyte, there are isotopically labeled internal standards and 7 deuterated calibrator points. Results. Performance characteristics are acceptable for both methods. Mean bias between methods calculated on 70 samples was 1.9 ng/mL. Linear regression analysis gave an R 2 of 0.94. 25-OHD2 is detectable only with PerkinElmer kit in derivatized assay option. Conclusion. Both methods are suitable for routine. Chromsystems kit minimizes manual sample preparation, requiring only protein precipitation, but, with our system, 25-OHD2 is not detectable. PerkinElmer kit without derivatization does not guarantee acceptable performance with our LC-MS/MS system, as sample is not purified online. Derivatization provides sufficient sensitivity for 25-OHD2 detection. PMID:23555079

Simple interface of high-performance liquid chromatography-atomic fluorescence spectrometry hyphenated system for speciation of mercury based on photo-induced chemical vapour generation with formic acid in mobile phase as reaction reagent.

PubMed

Yin, Yongguang; Liu, Jingfu; He, Bin; Shi, Jianbo; Jiang, Guibin

2008-02-15

Photo-induced chemical vapour generation (CVG) with formic acid in mobile phase as reaction reagent was developed as interface to on-line couple HPLC with atomic fluorescence spectrometry for the separation and determination of inorganic mercury, methylmercury (MeHg), ethylmercury (EtHg) and phenylmercury (PhHg). In the developed procedure, formic acid in mobile phase was used to decompose organomercuries and reduce Hg(2+) to mercury cold vapour under UV irradiation. Therefore, no post-column reagent was used and the flow injection system in traditional procedure is omitted. A number of operating parameters including pH of mobile phase, concentration of formate, flow rate of mobile phase, length of PTFE reaction coil, flow rate of carrier gas and Na(2)S(2)O(3) in sample matrix were optimized. The limits of detection at the optimized conditions were 0.085, 0.033, 0.029 and 0.038 microg L(-1) for inorganic mercury, MeHg, EtHg and PhHg, respectively. The developed method was validated by determination of certified reference material DORM-2 and was further applied in analyses of seafood samples from Yantai port, China. The UV-CVG with formic acid simplifies the instrumentation and reduces the analytical cost significantly.

[Osteological development of the vertebral column and caudal complex of Lujanus guttatus (Perciformes: Lutjanidae) larvae under rearing conditions].

PubMed

Rodríguez-Ibarra, Luz Estela; Abdo-de la Parra, María Isabel; Aguilar-Zárate, Gabriela; Valasco-Blanco, Gabriela; Ibarra-Castro, Leonardo

2015-03-01

The spotted rose snapper (Lutjanus guttatus) is an important commercial species in Mexico with good culture potential. The osteological study at early stages in this species is an important tool to confirm normal bone structure and for the detection of malformations that may occur during early development. This study was carried out in order to evaluate and describe the normal osteological development of the vertebral column and caudal complex of this species grown under controlled conditions. For this, a total of 540 larvae of L. guttatus, between 2.1 and 17.5 mm of total length (TL), were cultured during 36 days; culture conditions were 28 degrees C, 5.74 mg/L oxygen and 32.2 ups salinity with standard feeding rates. To detect growth changes, a sample of 15 organisms was daily taken from day one until day 36 of post-hatch (DPH). Samples were processed following standard techniques of clearing, and cartilage (alcian blue) and bone staining (alizarin red). Results showed that the vertebral column is composed of ten vertebrae in the abdominal region, and 14 vertebrae including the urostyle in the caudal region. The development of the axial skeleton starts with the neural arches and haemal arches at 3.8 mm TL. Caudal elements such as the hypurals and parahypural began to develop at 4.1 mm TL. Pre-flexion and flexion of the notochord and the formation of all hypurals were observed between 5.3 and 5.8 mm TL. Ossification of the vertebrae in the abdominal region and in some neural arches initiated at 9.5mm TL. In the caudal region, all the neural and haemal arches ossified at 10.2 mm TL. All the abdominal vertebrae and their respective neural arches and parapophyses ossified at 11.2 mm TL, while the elements of the caudal complex that ossified were the hypurals, parahypurals and modified haemal spines. All caudal fm rays, 12 neural spines and 3 haemal arches were ossified by 15.5 mm. The complete ossification process of this specie under laboratory culture conditions was observed when larvae reached 17.3 mm TL on 36 DPH. Detailed analysis of the osteological structures will allow a reference description to evaluate and detect malformations that may occur during the larval culture of the spotted rose snapper.

Study of different HILIC, mixed-mode, and other aqueous normal-phase approaches for the liquid chromatography/mass spectrometry-based determination of challenging polar pesticides.

PubMed

Vass, Andrea; Robles-Molina, José; Pérez-Ortega, Patricia; Gilbert-López, Bienvenida; Dernovics, Mihaly; Molina-Díaz, Antonio; García-Reyes, Juan F

2016-07-01

The aim of the study was to evaluate the performance of different chromatographic approaches for the liquid chromatography/mass spectrometry (LC-MS(/MS)) determination of 24 highly polar pesticides. The studied compounds, which are in most cases unsuitable for conventional LC-MS(/MS) multiresidue methods were tested with nine different chromatographic conditions, including two different hydrophilic interaction liquid chromatography (HILIC) columns, two zwitterionic-type mixed-mode columns, three normal-phase columns operated in HILIC-mode (bare silica and two silica-based chemically bonded columns (cyano and amino)), and two standard reversed-phase C18 columns. Different sets of chromatographic parameters in positive (for 17 analytes) and negative ionization modes (for nine analytes) were examined. In order to compare the different approaches, a semi-quantitative classification was proposed, calculated as the percentage of an empirical performance value, which consisted of three main features: (i) capacity factor (k) to characterize analyte separation from the void, (ii) relative response factor, and (iii) peak shape based on analytes' peak width. While no single method was able to provide appropriate detection of all the 24 studied species in a single run, the best suited approach for the compounds ionized in positive mode was based on a UHPLC HILIC column with 1.8 μm particle size, providing appropriate results for 22 out of the 24 species tested. In contrast, the detection of glyphosate and aminomethylphosphonic acid could only be achieved with a zwitterionic-type mixed-mode column, which proved to be suitable only for the pesticides detected in negative ion mode. Finally, the selected approach (UHPLC HILIC) was found to be useful for the determination of multiple pesticides in oranges using HILIC-ESI-MS/MS, with limits of quantitation in the low microgram per kilogram in most cases. Graphical Abstract HILIC improves separation of multiclass polar pesticides.

Separation of amino acids and antibiotics by narrow-bore and normal-bore high-performance liquid chromatography with pre-column derivatization.

PubMed

Fiedler, H P; Plaga, A

1987-01-16

The selectivity, efficiency and lifetime of normal- and narrow-bore columns for high-performance liquid chromatography were investigated for the separation and quantification of amino acids and the amino acid-like antibiotics phosphinothricin and phosphinothricylalanylalanine in biological samples. These compounds were determined by an automated pre-column derivatization with o-phthalaldehyde-2-mercaptoethanol reagent and UV detection at 338 nm.

Technetium-99m generator system

DOEpatents

Mirzadeh, Saed; Knapp, Jr., Furn F.; Collins, Emory D.

1998-01-01

A .sup.99 Mo/.sup.99m Tc generator system includes a sorbent column loaded with a composition containing .sup.99 Mo. The sorbent column has an effluent end in fluid communication with an anion-exchange column for concentrating .sup.99m Tc eluted from the sorbent column. A method of preparing a concentrated solution of .sup.99m Tc includes the general steps of: a. providing a sorbent column loaded with a composition containing .sup.99 Mo, the sorbent column having an effluent end in fluid communication with an anion-exchange column; b. eluting the sorbent column with a salt solution to elute .sup.99m Tc from the sorbent and to trap and concentrate the eluted .sup.99m Tc on the ion-exchange column; and c. eluting the concentrated .sup.99m Tc from the ion-exchange column with a solution comprising a reductive complexing agent.

Technetium-99m generator system

DOEpatents

Mirzadeh, S.; Knapp, F.F. Jr.; Collins, E.D.

1998-06-30

A {sup 99}Mo/{sup 99m}Tc generator system includes a sorbent column loaded with a composition containing {sup 99}Mo. The sorbent column has an effluent end in fluid communication with an anion-exchange column for concentrating {sup 99m}Tc eluted from the sorbent column. A method of preparing a concentrated solution of {sup 99m}Tc includes the general steps of: (a) providing a sorbent column loaded with a composition containing {sup 99}Mo, the sorbent column having an effluent end in fluid communication with an anion-exchange column; (b) eluting the sorbent column with a salt solution to elute {sup 99m}Tc from the sorbent and to trap and concentrate the eluted {sup 99m}Tc on the ion-exchange column; and (c) eluting the concentrated {sup 99m}Tc from the ion-exchange column with a solution comprising a reductive complexing agent. 1 fig.

Development of High Pressure Liquid Chromatographic Techniques

DTIC Science & Technology

1976-05-01

Silver tungstate was prepared by precipitation from equimolar solutions of sodium tungsten oxide (Na^Oj and silver nitrate {AgN03). The precipitate ...electro- chemical detector based on this observation. Various approaches were used. Silver iodide- tungstate was prepared in the following manner...Lamers, B. J. M., and Gerding, M. H., "A New Highly Sensitive Detection System for Peptides and Proteins in Column Effluents," J. Chrom., 66, 1972

Review of Advances in Cobb Angle Calculation and Image-Based Modelling Techniques for Spinal Deformities

NASA Astrophysics Data System (ADS)

Giannoglou, V.; Stylianidis, E.

2016-06-01

Scoliosis is a 3D deformity of the human spinal column that is caused from the bending of the latter, causing pain, aesthetic and respiratory problems. This internal deformation is reflected in the outer shape of the human back. The golden standard for diagnosis and monitoring of scoliosis is the Cobb angle, which refers to the internal curvature of the trunk. This work is the first part of a post-doctoral research, presenting the most important researches that have been done in the field of scoliosis, concerning its digital visualisation, in order to provide a more precise and robust identification and monitoring of scoliosis. The research is divided in four fields, namely, the X-ray processing, the automatic Cobb angle(s) calculation, the 3D modelling of the spine that provides a more accurate representation of the trunk and the reduction of X-ray radiation exposure throughout the monitoring of scoliosis. Despite the fact that many researchers have been working on the field for the last decade at least, there is no reliable and universal tool to automatically calculate the Cobb angle(s) and successfully perform proper 3D modelling of the spinal column that would assist a more accurate detection and monitoring of scoliosis.

Liquid chromatography-electrospray mass spectrometry of beta-carotene and xanthophylls. Validation of the analytical method.

PubMed

Careri, M; Elviri, L; Mangia, A

1999-08-27

The investigation of beta-carotene and the xanthophylls beta-cryptoxanthin, lutein, zeaxanthin, canthaxanthin and astaxanthin using reversed-phase liquid chromatography-electrospray mass spectrometry interfaced with TurboIonspray (LC-TurboISP-MS) is described. Two narrow-bore C18 columns connected in series and an isocratic solvent system containing acetonitrile-methanol (0.1 M ammonium acetate)-dichloromethane at a flow-rate of 300 microl/min (without splitting) were used. Operating in the positive-ion mode over m/z 500-650, the effects on the formation of the molecular ion species or adduct ions and the MS detector response were investigated for carotenoids, varying the orifice plate voltage, the ring voltage and the ISP voltage. Both conventional ISP and TurboISP were performed; using the TurboISP-MS system, ionization efficiency increased with respect to ISP-MS, particularly at the highest temperature (500 degrees C). Good results were particularly obtained for beta-carotene, which was detectable at the low ng level, without the use of solution-phase oxidants. Using LC columns and acquiring in single-ion monitoring mode, detection limits were estimated to be in the 0.1-1 ng range; dynamic range was established between one- and two-orders of magnitude. Better sensitivity under positive-ion than negative-ion conditions was demonstrated.

A fast automatic target detection method for detecting ships in infrared scenes

NASA Astrophysics Data System (ADS)

Özertem, Kemal Arda

2016-05-01

Automatic target detection in infrared scenes is a vital task for many application areas like defense, security and border surveillance. For anti-ship missiles, having a fast and robust ship detection algorithm is crucial for overall system performance. In this paper, a straight-forward yet effective ship detection method for infrared scenes is introduced. First, morphological grayscale reconstruction is applied to the input image, followed by an automatic thresholding onto the suppressed image. For the segmentation step, connected component analysis is employed to obtain target candidate regions. At this point, it can be realized that the detection is defenseless to outliers like small objects with relatively high intensity values or the clouds. To deal with this drawback, a post-processing stage is introduced. For the post-processing stage, two different methods are used. First, noisy detection results are rejected with respect to target size. Second, the waterline is detected by using Hough transform and the detection results that are located above the waterline with a small margin are rejected. After post-processing stage, there are still undesired holes remaining, which cause to detect one object as multi objects or not to detect an object as a whole. To improve the detection performance, another automatic thresholding is implemented only to target candidate regions. Finally, two detection results are fused and post-processing stage is repeated to obtain final detection result. The performance of overall methodology is tested with real world infrared test data.

[HPLC fingerprint of Calendula officinalis flower].

PubMed

Xing, Zhan-Fen; Cheng, Hong-Da; Zhang, Ping-Ping; Gong, Lei; Ma, Li-Ya

2014-07-01

To establish an HPLC fingerprint of Calendula officinalis flower for its quality control. Hypersil ODS C18 column (250 mm x 4.6 mm, 5 μm) was used with acetonitrile and water as mobile phase in a gradient mode at the flow rate of 1.0 mL/min. The detection wavelength was 220 nm and the temperature of column was set at 35 degrees C. The similarity was analyzed with the Estimating System of Similarity on the Chinese Medicine Fingerprint Chromatogram. The HPLC fingerprint of Calendula officinalis flower containing eleven peaks was set up. The similarity of Calendula officinalis flower from different habitats was greater than 0.90. This method is easy and reliable, which can be used to judge the habitat and control the quality of Calendula officinalis flower.

Experimental feasibility of the airborne measurement of absolute oil fluorescence spectral conversion efficiency

NASA Technical Reports Server (NTRS)

Hoge, F. E.; Swift, R. N.

1983-01-01

Airborne lidar oil spill experiments carried out to determine the practicability of the AOFSCE (absolute oil fluorescence spectral conversion efficiency) computational model are described. The results reveal that the model is suitable over a considerable range of oil film thicknesses provided the fluorescence efficiency of the oil does not approach the minimum detection sensitivity limitations of the lidar system. Separate airborne lidar experiments to demonstrate measurement of the water column Raman conversion efficiency are also conducted to ascertain the ultimate feasibility of converting such relative oil fluorescence to absolute values. Whereas the AOFSCE model is seen as highly promising, further airborne water column Raman conversion efficiency experiments with improved temporal or depth-resolved waveform calibration and software deconvolution techniques are thought necessary for a final determination of suitability.

Estimating the coordinates of pillars and posts in the parking lots for intelligent parking assist system

NASA Astrophysics Data System (ADS)

Choi, Jae Hyung; Kuk, Jung Gap; Kim, Young Il; Cho, Nam Ik

2012-01-01

This paper proposes an algorithm for the detection of pillars or posts in the video captured by a single camera implemented on the fore side of a room mirror in a car. The main purpose of this algorithm is to complement the weakness of current ultrasonic parking assist system, which does not well find the exact position of pillars or does not recognize narrow posts. The proposed algorithm is consisted of three steps: straight line detection, line tracking, and the estimation of 3D position of pillars. In the first step, the strong lines are found by the Hough transform. Second step is the combination of detection and tracking, and the third is the calculation of 3D position of the line by the analysis of trajectory of relative positions and the parameters of camera. Experiments on synthetic and real images show that the proposed method successfully locates and tracks the position of pillars, which helps the ultrasonic system to correctly locate the edges of pillars. It is believed that the proposed algorithm can also be employed as a basic element for vision based autonomous driving system.

Evaluation of mobile phase characteristics on three zwitterionic columns in hydrophilic interaction liquid chromatography mode for liquid chromatography-high resolution mass spectrometry based untargeted metabolite profiling of Leishmania parasites.

PubMed

Zhang, Rong; Watson, David G; Wang, Lijie; Westrop, Gareth D; Coombs, Graham H; Zhang, Tong

2014-10-03

It has been reported that HILIC column chemistry has a great effect on the number of detected metabolites in LC-HRMS-based untargeted metabolite profiling studies. However, no systematic investigation has been carried out with regard to the optimisation of mobile phase characteristics. In this study using 223 metabolite standards, we explored the retention mechanisms on three zwitterionic columns with varied mobile phase composition, demonstrated the interference from poor chromatographic peak shapes on the output of data extraction, and assessed the quality of chromatographic signals and the separation of isomers under each LC condition. As expected, on the ZIC-cHILIC column the acidic metabolites showed improved chromatographic performance at low pH which can be attributed to the opposite arrangement of the permanently charged groups on this column in comparison with the ZIC-HILIC column. Using extracts from the protozoan parasite Leishmania, we compared the numbers of repeatedly detected LC-HRMS features under different LC conditions with putative identification of metabolites not amongst the standards being based on accurate mass (±3ppm). Besides column chemistry, the pH of the mobile phase plays a key role in not only determining the retention mechanisms of solutes but also the output of the LC-HRMS data processing. Fast evaporation of ammonium carbonate produced less ion suppression in ESI source and consequently improved the detectability of the metabolites in low abundance in comparison with other ammonium salts. Our results show that the combination of a ZIC-pHILIC column with an ammonium carbonate mobile phase, pH 9.2, at 20mM in the aqueous phase or 10mM in both aqueous and organic mobile phase components, provided the most suitable LC conditions for LC-HRMS-based untargeted metabolite profiling of Leishmania parasite extracts. The signal reliability of the mass spectrometer used in this study (Exactive Orbitrap) was also investigated. Copyright © 2014 Elsevier B.V. All rights reserved.

Ion chromatographic methods for the detection of starch hydrolysis products in ruminal digesta.

PubMed

Barsuhn, K; Kotarski, S F

1991-06-21

Dionex high-performance ion chromatographic methods were evaluated for separation and quantitation of plant sugars and starch digestion products in the ruminal digesta of cattle. Mono- and disaccharides were eluted from a Dionex CarboPac PA1 column with sodium hydroxide used isocratically or as a pH gradient. Maltooligosaccharides which had a degree of polymerization (DP) less than 30 glucose residues were eluted in 60 min by a sodium hydroxide eluent containing a sodium acetate gradient. Carbohydrates were detected amperometrically. Responses were linear (r2 greater than 0.99) for glucose, disaccharides and maltooligosaccharides (DP less than 8). Precipitation and solid-phase extraction methods were evaluated for clean-up of samples of feedstuffs, ruminal contents, and bacterial culture fluids. Perchloric acid precipitation hydrolyzed sucrose but did not affect recoveries of cellobiose, isomaltose or maltose. Ethanol in concentrations of 79 and 86% precipitated maltooligosaccharides having chain lengths larger than 14 and 9 glucose residues, respectively. Maltooligosaccharide recoveries from solid-phase extraction columns varied with maltooligosaccharide size and column packing. Recoveries were greater than 94% for short chains (DP less than 6) eluted from phenyl-substituted columns and variable for all oligosaccharides eluted from C18 columns. Applications of these methods are presented and include: (1) detection of sugars in ruminant feed, (2) monitoring changes in ruminal sugars after feeding and (3) monitoring changes in extracellular sugars and oligosaccharides in the culture fluids of the ruminal bacterium, Bacteroides ruminicola.

Removal of Cr(VI) from groundwater by Fe(0)

NASA Astrophysics Data System (ADS)

Gao, Yanjiao; Liu, Rui

2017-11-01

This research was conducted to investigate the treatment of hexavalent chromium (Cr(VI)) by iron powder (Fe(0)) columns of simulated permeable reactive barriers with and without calcium carbonate (CaCO3). Two columns filled with Fe(0) were used as Cr(VI) removal equipment running at a flow velocity of 10 ml/min at room temperature. After 200 days running of the two columns, the results showed that Fe(0) was an effective material for Cr(VI) reduction with an average removal rate of above 84.6%. The performance of Column 2 with CaCO3 was better than Column 1 without CaCO3 in terms of average Cr(VI) removal rate. The presence of CaCO3 buffered the increasing pH caused by Fe(0) corrosion in Column 2 and enhanced the removal rate of Column 2. Scanning Electron Microscopy (SEM) images of Fe(0) in the three stages of running of the two columns illustrated that the coat layer of Column 1 was a little thicker than that of Column 2. Energy-dispersive spectrometry (EDS) results showed that the surface of Fe(0) of Column 2 contained more chromium elements. Raman spectroscopy found that all iron oxide was generated on the Fe(0) surface of Column 1 and Column 2 and chromium class objects were only detected on Fe(0) surface in Column 2.

Novel and sensitive reversed-phase high-pressure liquid chromatography method with electrochemical detection for the simultaneous and fast determination of eight biogenic amines and metabolites in human brain tissue.

PubMed

Van Dam, Debby; Vermeiren, Yannick; Aerts, Tony; De Deyn, Peter Paul

2014-08-01

A fast and simple RP-HPLC method with electrochemical detection (ECD) and ion pair chromatography was developed, optimized and validated in order to simultaneously determine eight different biogenic amines and metabolites in post-mortem human brain tissue in a single-run analytical approach. The compounds of interest are the indolamine serotonin (5-hydroxytryptamine, 5-HT), the catecholamines dopamine (DA) and (nor)epinephrine ((N)E), as well as their respective metabolites, i.e. 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), 5-hydroxy-3-indoleacetic acid (5-HIAA) and 3-methoxy-4-hydroxyphenylglycol (MHPG). A two-level fractional factorial experimental design was applied to study the effect of five experimental factors (i.e. the ion-pair counter concentration, the level of organic modifier, the pH of the mobile phase, the temperature of the column, and the voltage setting of the detector) on the chromatographic behaviour. The cross effect between the five quantitative factors and the capacity and separation factors of the analytes were then analysed using a Standard Least Squares model. The optimized method was fully validated according to the requirements of SFSTP (Société Française des Sciences et Techniques Pharmaceutiques). Our human brain tissue sample preparation procedure is straightforward and relatively short, which allows samples to be loaded onto the HPLC system within approximately 4h. Additionally, a high sample throughput was achieved after optimization due to a total runtime of maximally 40min per sample. The conditions and settings of the HPLC system were found to be accurate with high intra and inter-assay repeatability, recovery and accuracy rates. The robust analytical method results in very low detection limits and good separation for all of the eight biogenic amines and metabolites in this complex mixture of biological analytes. Copyright © 2014 Elsevier B.V. All rights reserved.

Fipronil mobility and transformation in undisturbed soil columns.

PubMed

Chatterjee, Niladri Sekhar; Gupta, Suman

2010-08-01

The downward movement of fipronil and its two toxic metabolites i.e. sulfone and desulfinyl were studied in undisturbed soil columns. Mobility behavior of two different formulations of fipronil viz granular and suspension concentrate were also studied. The undisturbed columns containing sandy loam soil were leached with water equivalent to 400 mm rainfall. Results revealed that although majority of the fipronil (approximately 80%) remained in top 0-5 cm layer, substantial amount (approximately 15%) moved to 5-10 cm depth. In case of metabolites sulfone and desulfinyl >90% of the residues remained in 0-5 cm core indicating low mobility of these metabolites in comparison to fipronil. Results of mobility behavior of fipronil in granular and SC formulations revealed low mobility in granular formulation. Sulfide was detected as the major degradation product in both the formulations and was found to be distributed throughout the column. A little amount of sulfone (0.1% of the total recovered) was also detected upto 10 cm depth.

Development of a Fabry-Perot Interferometer for Ultra-Precise Measurements of Column CO2

NASA Technical Reports Server (NTRS)

Wilson, Emily L.; Georgieva, Elena M.; Heaps, William S.

2005-01-01

A passive Fabry-Perot based instrument is described for detecting column CO2 through absorption measurements at 1.58 microns . In this design, solar flux reaches the instrument platform and is directed through two channels. In the first channel, transmittance fi5nges from a Fabry-Perot interferometer are aligned with CO2 absorption lines so that absorption due to CO2 is primarily detected. The second channel encompasses the same frequency region as the first, but is comparatively more sensitive to changes in the solar flux than absorption due to CO2. The ratio of these channels is sensitive to changes in the total CO2 column, but not to changes in solar flux. This inexpensive instrument will offer high precision measurements (error 4%) in a compact package. Design of this instrument and preliminary ground-based measurements of column CO2 are presented here as well as strategies for deployment on aircraft and satellite platforms.

Direct probing of chromatography columns by laser-induced fluorescence

NASA Astrophysics Data System (ADS)

McGuffin, V. L.

1992-12-01

This report summarizes the progress and accomplishments of this research project from 1 Sep. 1989 to 28 Feb. 1993. During this period, we have accomplished all of the primary scientific objectives of the research proposal: (1) constructed and evaluated a laser-induced fluorescence detection system that allows direct examination of the chromatographic column, (2) examined nonequilibrium processes that occur upon solute injection and elution, (3) examined solute retention in liquid chromatography as a function of temperature and pressure, (4) examined solute zone dispersion in liquid chromatography as a function of temperature and pressure, and (5) developed appropriate theoretical models to describe these phenomena. In each of these studies, substantial knowledge has been gained of the fundamental processes that are responsible for chromatographic separations. In addition to these primary research objectives, we have made significant progress in three related areas: (1) examined pyrene as a fluorescent polarity probe in supercritical fluids and liquids as a function of temperature and pressure, (2) developed methods for the class-selective identification of polynuclear aromatic hydrocarbons in coal-derived fluids by microcolumn liquid chromatography with fluorescence quenching detection, and (3) developed methods for the determination of saturated and unsaturated (including omega-3) fatty acids in fish oil extracts by microcolumn liquid chromatography with laser-induced fluorescence detection. In these studies, the advanced separation and detection techniques developed in our laboratory are applied to practical problems of environmental and biomedical significance.