Rapid and sensitive determination of major polyphenolic components in Euphoria longana Lam. seeds using matrix solid-phase dispersion extraction and UHPLC with hybrid linear ion trap triple quadrupole mass spectrometry.

PubMed

Rathore, Atul S; Sathiyanarayanan, L; Deshpande, Shreekant; Mahadik, Kakasaheb R

2016-11-01

A rapid and sensitive method for the extraction and determination of four major polyphenolic components in Euphoria longana Lam. seeds is presented for the first time based on matrix solid-phase dispersion extraction followed by ultra high performance liquid chromatography with hybrid triple quadrupole linear ion trap mass spectrometry. Matrix solid-phase dispersion method was designed for the extraction of Euphoria longana seed constituents and compared with microwave-assisted extraction and ultrasonic-assisted extraction methods. An Ultra high performance liquid chromatography with hybrid triple quadrupole linear ion-trap mass spectrometry method was developed for quantitative analysis in multiple-reaction monitoring mode in negative electrospray ionization. The chromatographic separation was accomplished using an ACQUITY UPLC BEH C 18 (2.1 mm × 50 mm, 1.7 μm) column with gradient elution of 0.1% aqueous formic acid and 0.1% formic acid in acetonitrile. The developed method was validated with acceptable linearity (r 2 > 0.999), precision (RSD ≤ 2.22%) and recovery (RSD ≤ 2.35%). The results indicated that matrix solid-phase dispersion produced comparable extraction efficiency compared with other methods nevertheless was more convenient and time-saving with reduced requirements on sample and solvent volumes. The proposed method is rapid and sensitive in providing a promising alternative for extraction and comprehensive determination of active components for quality control of Euphoria longana products. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydride Generation for Headspace Solid-Phase Extraction with CdTe Quantum Dots Immobilized on Paper for Sensitive Visual Detection of Selenium.

PubMed

Huang, Ke; Xu, Kailai; Zhu, Wei; Yang, Lu; Hou, Xiandeng; Zheng, Chengbin

2016-01-05

A low-cost, simple, and highly selective analytical method was developed for sensitive visual detection of selenium in human urine both outdoors and at home, by coupling hydride generation with headspace solid-phase extraction using quantum dots (QDs) immobilized on paper. The visible fluorescence from the CdTe QDs immobilized on paper was quenched by H2Se from hydride generation reaction and headspace solid-phase extraction. The potential mechanism was investigated by using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) as well as Density Functional Theory (DFT). Potential interferences from coexisting ions, particularly Ag(+), Cu(2+), and Zn(2+), were eliminated. The selectivity was significantly increased because the selenium hydride was effectively separated from sample matrices by hydride generation. Moreover, due to the high sampling efficiency of hydride generation and headspace solid phase extraction, the sensitivity and the limit of detection (LOD) were significantly improved compared to conventional methods. A LOD of 0.1 μg L(-1) and a relative standard deviation (RSD, n = 7) of 2.4% at a concentration of 20 μg L(-1) were obtained when using a commercial spectrofluorometer as the detector. Furthermore, a visual assay based on the proposed method was developed for the detection of Se, 5 μg L(-1) of selenium in urine can be discriminated from the blank solution with the naked eye. The proposed method was validated by analysis of certified reference materials and human urine samples with satisfactory results.

Comparing the catalytic oxidation of ethanol at the solid-gas and solid-liquid interfaces over size-controlled Pt nanoparticles: striking differences in kinetics and mechanism.

PubMed

Sapi, Andras; Liu, Fudong; Cai, Xiaojun; Thompson, Christopher M; Wang, Hailiang; An, Kwangjin; Krier, James M; Somorjai, Gabor A

2014-11-12

Pt nanoparticles with controlled size (2, 4, and 6 nm) are synthesized and tested in ethanol oxidation by molecular oxygen at 60 °C to acetaldehyde and carbon dioxide both in the gas and liquid phases. The turnover frequency of the reaction is ∼80 times faster, and the activation energy is ∼5 times higher at the gas-solid interface compared to the liquid-solid interface. The catalytic activity is highly dependent on the size of the Pt nanoparticles; however, the selectivity is not size sensitive. Acetaldehyde is the main product in both media, while twice as much carbon dioxide was observed in the gas phase compared to the liquid phase. Added water boosts the reaction in the liquid phase; however, it acts as an inhibitor in the gas phase. The more water vapor was added, the more carbon dioxide was formed in the gas phase, while the selectivity was not affected by the concentration of the water in the liquid phase. The differences in the reaction kinetics of the solid-gas and solid-liquid interfaces can be attributed to the molecular orientation deviation of the ethanol molecules on the Pt surface in the gas and liquid phases as evidenced by sum frequency generation vibrational spectroscopy.

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

Urtiew, P A; Forbes, J W; Tarver, C M

LX-04 is a widely used HMX-based plastic bonded explosive, which contains 85 weight % HMX and 15 weight % Viton binder. The sensitivity of LX-04 to a single stimulus such as heat, impact, and shock has been previously studied. However, hazard scenarios can involve multiple stimuli, such as heating to temperatures close to thermal explosion conditions followed by fragment impact, producing a shock in the hot explosive. The sensitivity of HMX at elevated temperatures is further complicated by the beta to delta solid-state phase transition, which occurs at approximately 165 C. This paper presents the results of shock initiation experimentsmore » conducted with LX-04 preheated to 190 C, as well as density measurements and small scale safety test results of the {delta} phase HMX at room temperature. This work shows that LX-04 at 190 C is more shock sensitive than LX-04 at 150 C or 170 C due to the volume increase during the {beta} to {delta} solid phase transition, which creates more hot spots, and the faster growth of reaction during shock compression.« less

Porous organic polymers with different pore structures for sensitive solid-phase microextraction of environmental organic pollutants.

PubMed

Huang, Zhoubing; Liu, Shuqin; Xu, Jianqiao; Yin, Li; Zheng, Juan; Zhou, Ningbo; Ouyang, Gangfeng

2017-10-09

Adsorption capacity is the major sensitivity-limited factor in solid-phase microextraction. Due to its light-weight properties, large specific surface area and high porosity, especially tunable pore structures, the utilization of porous organic polymers as solid-phase microextraction adsorbents has attracting researchers' attentions. However, these works mostly concentrated on the utilization of specific porous organic polymers for preparing high-performance solid-phase microextraction coatings. The relationship between pore structures and adsorption performance of the porous organic polymers still remain unclear. Herein, three porous organic polymers with similar properties but different pore distributions were prepared by condensation polymerization reaction of phloroglucinol and terephthalaldehyde, which were fabricated as solid-phase microextraction coatings subsequently. The adsorption capacity of the porous organic polymers-coated fibers were evaluated by using benzene and its derivatives (i.e.,benzene, toluene, ethylbenzene and m-xylene) and polycyclic aromatic hydrocarbons as the target analytes. The results showed that the different adsorption performance of these porous organic polymers was mainly caused by their different pore volumes instead of their surface areas or pore sizes. Finally, the proposed method by using the mesoporous organic polymer coating was successfully applied to the determination of benzene and its derivatives in environmental water samples. As for analytical performance, high pre-concentration factors (74-2984), satisfactory relative recoveries (94.5 ± 18.5-116.9 ± 12.5%), intraday precision (2.44-5.34%), inter-day precision (4.62-7.02%), low limit of detections (LODs, 0.10-0.29 ng L -1 ) and limit of quantifications (LOQs, 0.33-0.96 ng L -1 ) were achieved under the optimal conditions. This study provides an important idea in the rational design of porous organic polymers for solid-phase microextraction or other adsorption applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Solid-phase fullerene-like nanostructures as singlet oxygen photosensitizers in liquid media

NASA Astrophysics Data System (ADS)

Belousova, I. M.; Danilov, O. B.; Kiselev, V. M.; Kislyakov, I. M.; Kris'ko, T. K.; Murav'eva, T. D.; Videnichev, D. A.

2007-04-01

Singlet oxygen generation by fullerene and astralen containing surfaces and powders under visible irradiation was studied in water and organic liquids by means of 1Δ g state luminescence and chemical scavenger transmittance measurements. The chemical method, pioneered for solid photosensitizers of 10 II, allowed to measure the singlet oxygen concentration in the aqueous medium down to 10 8 cm -3. The singlet oxygen sensitizing by the solid-phase fullerene-containing systems was found to be 100 times less effective then by fullerene in solution. The results obtained confirm the applicability of these structures in biology and medicine.

Interfacial chemistry and the design of solid-phase nucleic acid hybridization assays using immobilized quantum dots as donors in fluorescence resonance energy transfer.

PubMed

Algar, W Russ; Krull, Ulrich J

2011-01-01

The use of quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET) offer several advantages for the development of multiplexed solid-phase QD-FRET nucleic acid hybridization assays. Designs for multiplexing have been demonstrated, but important challenges remain in the optimization of these systems. In this work, we identify several strategies based on the design of interfacial chemistry for improving sensitivity, obtaining lower limits of detection (LOD) and enabling the regeneration and reuse of solid-phase QD-FRET hybridization assays. FRET-sensitized emission from acceptor dyes associated with hybridization events at immobilized QD donors provides the analytical signal in these assays. The minimization of active sensing area reduces background from QD donor PL and allows the resolution of smaller amounts of acceptor emission, thus lowering the LOD. The association of multiple acceptor dyes with each hybridization event can enhance FRET efficiency, thereby improving sensitivity. Many previous studies have used interfacial protein layers to generate selectivity; however, transient destabilization of these layers is shown to prevent efficient regeneration. To this end, we report a protein-free interfacial chemistry and demonstrate the specific detection of as little as 2 pmol of target, as well as an improved capacity for regeneration.

Interfacial Chemistry and the Design of Solid-Phase Nucleic Acid Hybridization Assays Using Immobilized Quantum Dots as Donors in Fluorescence Resonance Energy Transfer

PubMed Central

Algar, W. Russ; Krull, Ulrich J.

2011-01-01

The use of quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET) offer several advantages for the development of multiplexed solid-phase QD-FRET nucleic acid hybridization assays. Designs for multiplexing have been demonstrated, but important challenges remain in the optimization of these systems. In this work, we identify several strategies based on the design of interfacial chemistry for improving sensitivity, obtaining lower limits of detection (LOD) and enabling the regeneration and reuse of solid-phase QD-FRET hybridization assays. FRET-sensitized emission from acceptor dyes associated with hybridization events at immobilized QD donors provides the analytical signal in these assays. The minimization of active sensing area reduces background from QD donor PL and allows the resolution of smaller amounts of acceptor emission, thus lowering the LOD. The association of multiple acceptor dyes with each hybridization event can enhance FRET efficiency, thereby improving sensitivity. Many previous studies have used interfacial protein layers to generate selectivity; however, transient destabilization of these layers is shown to prevent efficient regeneration. To this end, we report a protein-free interfacial chemistry and demonstrate the specific detection of as little as 2 pmol of target, as well as an improved capacity for regeneration. PMID:22163951

Rapid and Sensitive Quantification of Vibrio cholerae and Vibrio mimicus Cells in Water Samples by Use of Catalyzed Reporter Deposition Fluorescence In Situ Hybridization Combined with Solid-Phase Cytometry

PubMed Central

Schauer, Sonja; Sommer, Regina; Farnleitner, Andreas H.

2012-01-01

A new protocol for rapid, specific, and sensitive cell-based quantification of Vibrio cholerae/Vibrio mimicus in water samples was developed. The protocol is based on catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH) in combination with solid-phase cytometry. For pure cultures, we were able to quantify down to 6 V. cholerae cells on one membrane with a relative precision of 39% and down to 12 cells with a relative precision of 17% after hybridization with the horseradish peroxidase (HRP)-labeled probe Vchomim1276 (specific for V. cholerae and V. mimicus) and signal amplification. The corresponding position of the probe on the 16S rRNA is highly accessible even when labeled with HRP. For the first time, we were also able to successfully quantify V. cholerae/V. mimicus via solid-phase cytometry in extremely turbid environmental water samples collected in Austria. Cell numbers ranged from 4.5 × 101 cells ml−1 in the large saline lake Neusiedler See to 5.6 × 104 cells ml−1 in an extremely turbid shallow soda lake situated nearby. We therefore suggest CARD-FISH in combination with solid-phase cytometry as a powerful tool to quantify V. cholerae/V. mimicus in ecological studies as well as for risk assessment and monitoring programs. PMID:22885749

Er:Yb phosphate glass laser with nonlinear absorber for phase-sensitive optical time domain reflectometry

NASA Astrophysics Data System (ADS)

Zhirnov, A. A.; Pnev, A. B.; Svelto, C.; Norgia, M.; Pesatori, A.; Galzerano, G.; Laporta, P.; Shelestov, D. A.; Karasik, V. E.

2017-11-01

A novel laser for phase-sensitive optical time-domain reflectometry (Φ-OTDR) is presented. The advantages of a compact solid-state laser are listed, current problems are shown. Experiments with a microchip single-optical-element laser, from setup construction to usage in Φ-OTDR system, are presented. New laser scheme with two-photon intracavity absorber is suggested and its advantages are described.

A chemometric strategy for optimization of solid-phase microextraction: determination of bisphenol A and 4-nonylphenol with HPLC.

PubMed

Liu, Xiaoyan; Zhang, Xiaoyun; Zhang, Haixia; Liu, Mancang

2008-08-01

A sensitive method for the analysis of bisphenol A and 4-nonylphenol is developed by means of the optimization of solid-phase microextraction using Uniform Experimental Design methodology followed by high-performance liquid chromatographic analysis with fluorescence detection. The optimal extraction conditions are determined based on the relationship between parameters and the peak area. The curve calibration plots are linear (r2>or=0.9980) over the concentration range of 1.25-125 ng/mL for bisphenol A and 2.59-202.96 ng/mL for 4-nonylphenol, respectively. The detection limits, based on a signal-to-noise ratio of 3, are 0.097 ng/mL for bisphenol A and 0.27 ng/mL for 4-nonylphenol, respectively. The validity of the proposed method is demonstrated by the analysis of the investigated analytes in real water samples and sensitivity of the optimized method is verified by comparing results with those obtained by previous methods using the same commercial solid-phase microextraction fiber.

A Novel Phase Sensitive Quantum Well Nanostructure Scheme for Controlling Optical Bistability

NASA Astrophysics Data System (ADS)

Raheli, Ali

2018-04-01

A novel four-level lambda-type quantum well (QW) nanostructure is proposed based on phase sensitive optical bistability (OB) and multistability (OM) with a closed-loop configuration. The influence of controlling parameters of the system on OB and OM is investigated. In particular, it is found that the OB behavior is strongly sensitive to the relative phase of applied fields. It is also shown that under certain parametric conditions, the OB can be switched to OM or vice versa. The controllability of OB/OM in such a QW nanostructure may bring some new possibilities for technological applications in solid-state quantum information science and optoelectronics.

Solid-Solid Phase Transition Kinetics of FOX-7

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

Burnham, A K; Weese, R K; Wang, R

Since it was developed in the late 1990s, 1,1-diamino-2,2-dinitroethene (FOX-7), with lower sensitivity and comparable performance to RDX, has received increasing interest. This paper will present our results for the phase changes of FOX-7 using DSC and HFC (Heat Flow Calorimetry). DSC thermal curves recorded at linear heating rates of 0.10, 0.35 and 1.0 C min{sup -1} show two endothermic peaks and two exothermic peaks. The two endothermic peaks represent solid-solid phase transitions, which have been observed in the literature at 114 C ({beta}-{gamma}) and 159 C ({gamma}-{delta}) by both DSC and XPD (X-ray powder diffraction) measurements. The first transitionmore » shifts from 114.5 to 115.8 C as the heating rate increases from 0.10 to 1.0 C min{sup -1}, while the second transition shifts from 158.5 to 160.4 C. Cyclical heating experiments show the endotherms and exotherms for a first heating through the {gamma} phase to the {delta} phase, a cooling and reversion to the {alpha} or {beta} phase, and a second heating to the {gamma} and {delta} phases. The data are interpreted using kinetic models with thermodynamic constraints.« less

SELECTIVE TRACE ENRICHMENT BY IMMUNOAFFINITY CAPILLARY ELECTROCHROMATOGRAPHY ON-LINE WITH CAPILLARY ZONE ELECTROPHORESIS - LASER-INDUCED FLUORESCENCE

EPA Science Inventory

Limited by the lack of a sensitive, universal detector, many capillary-based liquid-phase separation techniques might benefit from techniques that overcome modest concentration sensitivity by preconcentrating large injection volumes. The work presented employs selective solid-ph...

Comparison of HPMC based polymers performance as carriers for manufacture of solid dispersions using the melt extruder.

PubMed

Ghosh, Indrajit; Snyder, Jennifer; Vippagunta, Radha; Alvine, Marilyn; Vakil, Ronak; Tong, Wei-Qin; Vippagunta, Sudha

2011-10-31

Preparation of amorphous solid dispersions using hot-melt extrusion process for poorly water soluble compounds which degrade on melting remains a challenge due to exposure to high temperatures. The aim of this study was to develop a physically and chemically stable amorphous solid dispersion of a poorly water-soluble compound, NVS981, which is highly thermal sensitive and degrades upon melting at 165 °C. Hydroxypropyl Methyl Cellulose (HPMC) based polymers; HPMC 3cps, HPMC phthalate (HPMCP) and HPMC acetyl succinate (HPMCAS) were selected as carriers to prepare solid dispersions using hot melt extrusion because of their relatively low glass transition temperatures. The solid dispersions were compared for their ease of manufacturing, physical stability such as recrystallization potential, phase separation, molecular mobility and enhancement of drug dissolution. Two different drug loads of 20 and 50% (w/w) were studied in each polymer system. It was interesting to note that solid dispersions with 50% (w/w) drug load were easier to process in the melt extruder compared to 20% (w/w) drug load in all three carriers, which was attributed to the plasticizing behavior of the drug substance. Upon storage at accelerated stability conditions, no phase separation was observed in HPMC 3cps and HPMCAS solid dispersions at the lower and higher drug load, whereas for HPMCP, phase separation was observed at higher drug load after 3 months. The pharmaceutical performance of these solid dispersions was evaluated by studying drug dissolution in pH 6.8 phosphate buffer. Drug release from solid dispersion prepared from polymers used for enteric coating, i.e. HPMCP and HPMCAS was faster compared with the water soluble polymer HPMC 3cps. In conclusion, of the 3 polymers studied for preparing solid dispersions of thermally sensitive compound using hot melt extrusion, HPMCAS was found to be the most promising as it was easily processible and provided stable solid dispersions with enhanced dissolution. Copyright © 2011 Elsevier B.V. All rights reserved.

Derivatization of peptides as quaternary ammonium salts for sensitive detection by ESI-MS.

PubMed

Cydzik, Marzena; Rudowska, Magdalena; Stefanowicz, Piotr; Szewczuk, Zbigniew

2011-06-01

A series of model peptides in the form of quaternary ammonium salts at the N-terminus was efficiently prepared by the solid-phase synthesis. Tandem mass spectrometric analysis of the peptide quaternary ammonium derivatives was shown to provide sequence confirmation and enhanced detection. We designed the 2-(1,4-diazabicyclo[2.2.2] octylammonium)acetyl quaternary ammonium group which does not suffer from neutral losses during MS/MS experiments. The presented quaternization of 1,4-diazabicyclo[2.2.2]octane (DABCO) by iodoacetylated peptides is relatively easy and compatible with standard solid-phase peptide synthesis. This methodology offers a novel sensitive approach to analyze peptides and other compounds. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.

Phase transition detection by surface photo charge effect in liquid crystals

NASA Astrophysics Data System (ADS)

Ivanov, O.; Petrov, M.; Naradikian, H.; Perez-Diaz, J. L.

2018-05-01

The surface photo charge effect (SPCE) was applied for the first time at structure and phase transitions study of hydrogen bonded in dimer liquid crystals (HBDLCs). Due to the high sensitivity of this method, besides first-order phase transitions, characteristic for the p,n-octyloxibenzoic acids (8OBA), an order transition was definitely detected within the nematic range. We state that the SPCE, arising at the solid-HBDLCs interface due to the double electrical layer, is invariably concomitant with solid surface-liquid interfaces, and indicates that the changes of the characteristics of this layer, under incident optical irradiation, induce surface charge rearrangement and alternating potential difference. A mechanism of induction of the SPCE at the interface of solid surface-anisotropic liquids is proposed. We also indicate that this mechanism can be adapted for solid surface-isotropic liquid interface, including colloids (milk) and fog (aerosols)-condensed medium.

Analysis of imazaquin in soybeans by solid-phase extraction and high-performance liquid chromatography.

PubMed

Guo, C; Hu, J-Y; Chen, X-Y; Li, J-Z

2008-02-01

An analytical method for the determination imazaquin residues in soybeans was developed. The developed liquid/liquid partition and strong anion exchange solid-phase extraction procedures provide the effective cleanup, removing the greatest number of sample matrix interferences. By optimizing mobile-phase pH water/acetonitrile conditions with phosphoric acid, using a C-18 reverse-phase chromatographic column and employing ultraviolet detection, excellent peak resolution was achieved. The combined cleanup and chromatographic method steps reported herein were sensitive and reliable for determining the imazaquin residues in soybean samples. This method is characterized by recovery >88.4%, precision <6.7% CV, and sensitivity of 0.005 ppm, in agreement with directives for method validation in residue analysis. Imazaquin residues in soybeans were further confirmed by high performance liquid chromatography-mass spectrometry (LC-MS). The proposed method was successfully applied to the analysis of imazaquin residues in soybean samples grown in an experimental field after treatments of imazaquin formulation.

Solid state SPS microwave generation and transmission study. Volume 2, phase 2: Appendices

NASA Technical Reports Server (NTRS)

Maynard, O. E.

1980-01-01

The solid state sandwich concept for SPS was further defined. The design effort concentrated on the spacetenna, but did include some system analysis for parametric comparison reasons. Basic solid state microwave devices were defined and modeled. An initial conceptual subsystems and system design was performed as well as sidelobe control and system selection. The selected system concept and parametric solid state microwave power transmission system data were assessed relevant to the SPS concept. Although device efficiency was not a goal, the sensitivities to design of this efficiency were parametrically treated. Sidelobe control consisted of various single step tapers, multistep tapers and Gaussian tapers. A hybrid concept using tubes and solid state was evaluated. Thermal analyses are included with emphasis on sensitivities to waste heat radiator form factor, emissivity, absorptivity, amplifier efficiency, material and junction temperature.

Simultaneous determination of azathioprine and 6-mercaptopurine by high-performance liquid chromatography.

PubMed

Van Os, E C; McKinney, J A; Zins, B J; Mays, D C; Schriver, Z H; Sandborn, W J; Lipsky, J J

1996-04-26

A specific, sensitive, single-step solid-phase extraction and reversed-phase high-performance liquid chromatographic method for the simultaneous determination of plasma 6-mercaptopurine and azathioprine concentrations is reported. Following solid-phase extraction, analytes are separated on a C18 column with mobile phase consisting of 0.8% acetonitrile in 1 mM triethylamine, pH 3.2, run on a gradient system. Quantitation limits were 5 ng/ml and 2 ng/ml for azathioprine and 6-mercaptopurine, respectively. Peak heights correlated linearly to known extracted standards for 6-mercaptopurine and azathioprine (r = 0.999) over a range of 2-200 ng/ml. No chromatographic interferences were detected.

Mechanism and microstructures in Ga2O3 pseudomartensitic solid phase transition.

PubMed

Zhu, Sheng-Cai; Guan, Shu-Hui; Liu, Zhi-Pan

2016-07-21

Solid-to-solid phase transition, although widely exploited in making new materials, challenges persistently our current theory for predicting its complex kinetics and rich microstructures in transition. The Ga2O3α-β phase transformation represents such a common but complex reaction with marked change in cation coordination and crystal density, which was known to yield either amorphous or crystalline products under different synthetic conditions. Here we, via recently developed stochastic surface walking (SSW) method, resolve for the first time the atomistic mechanism of Ga2O3α-β phase transformation, the pathway of which turns out to be the first reaction pathway ever determined for a new type of diffusionless solid phase transition, namely, pseudomartensitic phase transition. We demonstrate that the sensitivity of product crystallinity is caused by its multi-step, multi-type reaction pathway, which bypasses seven intermediate phases and involves all types of elementary solid phase transition steps, i.e. the shearing of O layers (martensitic type), the local diffusion of Ga atoms (reconstructive type) and the significant lattice dilation (dilation type). While the migration of Ga atoms across the close-packed O layers is the rate-determining step and yields "amorphous-like" high energy intermediates, the shearing of O layers contributes to the formation of coherent biphase junctions and the presence of a crystallographic orientation relation, (001)α//(201[combining macron])β + [120]α//[13[combining macron]2]β. Our experiment using high-resolution transmission electron microscopy further confirms the theoretical predictions on the atomic structure of biphase junction and the formation of (201[combining macron])β twin, and also discovers the late occurrence of lattice expansion in the nascent β phase that grows out from the parent α phase. By distinguishing pseudomartensitic transition from other types of mechanisms, we propose general rules to predict the product crystallinity of solid phase transition. The new knowledge on the kinetics of pseudomartensitic transition complements the theory of diffusionless solid phase transition.

Variables controlling the recovery of ignitable liquid residues from simulated fire debris samples using solid-phase microextraction/gas chromatography

NASA Astrophysics Data System (ADS)

Furton, Kenneth G.; Almirall, Jose R.; Wang, Jing

1999-02-01

In this paper, we present data comparing a variety of different conditions for extracting ignitable liquid residues from simulated fire debris samples in order to optimize the conditions for using Solid Phase Microextraction. A simulated accelerant mixture containing 30 components, including those from light petroleum distillates, medium petroleum distillates and heavy petroleum distillates were used to study the important variables controlling Solid Phase Microextraction (SPME) recoveries. SPME is an inexpensive, rapid and sensitive method for the analysis of volatile residues from the headspace over solid debris samples in a container or directly from aqueous samples followed by GC. The relative effects of controllable variables, including fiber chemistry, adsorption and desorption temperature, extraction time, and desorption time, have been optimized. The addition of water and ethanol to simulated debris samples in a can was shown to increase the sensitivity when using headspace SPME extraction. The relative enhancement of sensitivity has been compared as a function of the hydrocarbon chain length, sample temperature, time, and added ethanol concentrations. The technique has also been optimized to the extraction of accelerants directly from water added to the fire debris samples. The optimum adsorption time for the low molecular weight components was found to be approximately 25 minutes. The high molecular weight components were found at a higher concentration the longer the fiber was exposed to the headspace (up to 1 hr). The higher molecular weight components were also found in higher concentrations in the headspace when water and/or ethanol was added to the debris.

On-line solid-phase microextraction of triclosan, bisphenol A, chlorophenols, and selected pharmaceuticals in environmental water samples by high-performance liquid chromatography-ultraviolet detection.

PubMed

Kim, Dalho; Han, Jungho; Choi, Yongwook

2013-01-01

A method using on-line solid-phase microextraction (SPME) on a carbowax-templated fiber followed by liquid chromatography (LC) with ultraviolet (UV) detection was developed for the determination of triclosan in environmental water samples. Along with triclosan, other selected phenolic compounds, bisphenol A, and acidic pharmaceuticals were studied. Previous SPME/LC or stir-bar sorptive extraction/LC-UV for polar analytes showed lack of sensitivity. In this study, the calculated octanol-water distribution coefficient (log D) values of the target analytes at different pH values were used to estimate polarity of the analytes. The lack of sensitivity observed in earlier studies is identified as a lack of desorption by strong polar-polar interactions between analyte and solid-phase. Calculated log D values were useful to understand or predict the interaction between analyte and solid phase. Under the optimized conditions, the method detection limit of selected analytes by using on-line SPME-LC-UV method ranged from 5 to 33 ng L(-1), except for very polar 3-chlorophenol and 2,4-dichlorophenol which was obscured in wastewater samples by an interfering substance. This level of detection represented a remarkable improvement over the conventional existing methods. The on-line SPME-LC-UV method, which did not require derivatization of analytes, was applied to the determination of TCS including phenolic compounds and acidic pharmaceuticals in tap water and river water and municipal wastewater samples.

Sensitive determination of three aconitum alkaloids and their metabolites in human plasma by matrix solid-phase dispersion with vortex-assisted dispersive liquid-liquid microextraction and HPLC with diode array detection.

PubMed

Wang, Xiaozhong; Li, Xuwen; Li, Lanjie; Li, Min; Liu, Ying; Wu, Qian; Li, Peng; Jin, Yongri

2016-05-01

A simple and sensitive method for determination of three aconitum alkaloids and their metabolites in human plasma was developed using matrix solid-phase dispersion combined with vortex-assisted dispersive liquid-liquid microextraction and high-performance liquid chromatography with diode array detection. The plasma sample was directly purified by matrix solid-phase dispersion and the eluate obtained was concentrated and further clarified by vortex-assisted dispersive liquid-liquid microextraction. Some important parameters affecting the extraction efficiency, such as type and amount of dispersing sorbent, type and volume of elution solvent, type and volume of extraction solvent, salt concentration as well as sample solution pH, were investigated in detail. Under optimal conditions, the proposed method has good repeatability and reproducibility with intraday and interday relative standard deviations lower than 5.44 and 5.75%, respectively. The recoveries of the aconitum alkaloids ranged from 73.81 to 101.82%, and the detection limits were achieved within the range of 1.6-2.1 ng/mL. The proposed method offered the advantages of good applicability, sensitivity, simplicity, and feasibility, which makes it suitable for the determination of trace amounts of aconitum alkaloids in human plasma samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sensitivity enhancement for nitrophenols using cationic surfactant-modified activated carbon for solid-phase extraction surface-assisted laser desorption/ionization mass spectrometry.

PubMed

Chen, Y C; Tsai, M F

2000-01-01

Previous work has demonstrated that a combination of solid-phase extraction with surface-assisted laser desorption/ionization (SPE-SALDI) mass spectrometry can be applied to the determination of trace nitrophenols in water. An improved method to lower the detection limit of this hyphenated technique is described in this present study. Activated carbon powder is used as both the SPE adsorbent and the SALDI solid in the analysis by SPE-SALDI. The surface of the activated carbon is modified by passing an aqueous solution of a cationic surfactant through the SPE cartridge. The results demonstrate that the sensitivity for nitrophenols in the analysis by SPE-SALDI can be improved by using cationic surfactants to modify the surface of the activated carbon. The detection limit for nitrophenols is about 25 ppt based on a signal-to-noise ratio of 3 by sampling from 100 mL of solution. Copyright 2000 John Wiley & Sons, Ltd.

Solid state SPS microwave generation and transmission study. Volume 1: Phase 2

NASA Technical Reports Server (NTRS)

Maynard, O. E.

1980-01-01

The solid state sandwich concept for Solar Power Station (SPS) was investigated. The design effort concentrated on the spacetenna, but did include some system analysis for parametric comparison reasons. The study specifically included definition and math modeling of basic solid state microwave devices, an initial conceptual subsystems and system design, sidelobe control and system selection, an assessment of selected system concept and parametric solid state microwave power transmission system data relevant to the SPS concept. Although device efficiency was not a goal, the sensitivities to design of this efficiency were parametrically treated. Sidelobe control consisted of various single step tapers, multistep tapers, and Gaussian tapers. A preliminary assessment of a hybrid concept using tubes and solid state is also included. There is a considerable amount of thermal analysis provided with emphasis on sensitivities to waste heat radiator form factor, emissivity, absorptivity, amplifier efficiency, material and junction temperature.

Criteria for the selection of a solid phase to be used in immunoassays.

PubMed

Delagneau, J F; Masseyeff, R

1990-01-01

Heterogeneous immunoassays are very sensitive and only limited in terms of performance by non specific binding. They require separation of free from bound fractions and concomitant use of a solid phase coated with an immunoreactive component (i.e. immunosorbent). The improvement of these key immunosorbents is crucial and involves a great deal of expertise and capabilities. Specifications differ according to procedure (e.g. capture or competitive assay). Each routinely used solid phase, such as polystyrene wells, porous membrane or dispersible microbeads, presents specific performance characteristics, advantages, and drawbacks. Among the tasks to be implemented are optimization of the spatial orientation of immunological reagents, selection of the surface neutral hydrophilic support, acceleration of reactions by increasing the reactive surface area of the supports, streamlining and simplification of procedural steps. These various aspects are abundantly described and emphasized here.

Development and Validation of HPLC Method for Determination of Crocetin, a constituent of Saffron, in Human Serum Samples.

PubMed

Mohammadpour, Amir Hooshang; Ramezani, Mohammad; Tavakoli Anaraki, Nasim; Malaekeh-Nikouei, Bizhan; Amel Farzad, Sara; Hosseinzadeh, Hossein

2013-01-01

The present study reports the development and validation of a sensitive and rapid extraction method beside high performance liquid chromatographic method for the determination of crocetin in human serum. The HPLC method was carried out by using a C18 reversed-phase column and a mobile phase composed of methanol/water/acetic acid (85:14.5:0.5 v/v/v) at the flow rate of 0.8 ml/min. The UV detector was set at 423 nm and 13-cis retinoic acid was used as the internal standard. Serum samples were pretreated with solid-phase extraction using Bond Elut C18 (200mg) cartridges or with direct precipitation using acetonitrile. The calibration curves were linear over the range of 0.05-1.25 µg/ml for direct precipitation method and 0.5-5 µg/ml for solid-phase extraction. The mean recoveries of crocetin over a concentration range of 0.05-5 µg/ml serum for direct precipitation method and 0.5-5 µg/ml for solid-phase extraction were above 70 % and 60 %, respectively. The intraday coefficients of variation were 0.37- 2.6% for direct precipitation method and 0.64 - 5.43% for solid-phase extraction. The inter day coefficients of variation were 1.69 - 6.03% for direct precipitation method and 5.13-12.74% for solid-phase extraction, respectively. The lower limit of quantification for crocetin was 0.05 µg/ml for direct precipitation method and 0.5 µg/ml for solid-phase extraction. The validated direct precipitation method for HPLC satisfied all of the criteria that were necessary for a bioanalytical method and could reliably quantitate crocetin in human serum for future clinical pharmacokinetic study.

Development and Validation of HPLC Method for Determination of Crocetin, a constituent of Saffron, in Human Serum Samples

PubMed Central

Mohammadpour, Amir Hooshang; Ramezani, Mohammad; Tavakoli Anaraki, Nasim; Malaekeh-Nikouei, Bizhan; Amel Farzad, Sara; Hosseinzadeh, Hossein

2013-01-01

Objective(s): The present study reports the development and validation of a sensitive and rapid extraction method beside high performance liquid chromatographic method for the determination of crocetin in human serum. Materials and Methods: The HPLC method was carried out by using a C18 reversed-phase column and a mobile phase composed of methanol/water/acetic acid (85:14.5:0.5 v/v/v) at the flow rate of 0.8 ml/min. The UV detector was set at 423 nm and 13-cis retinoic acid was used as the internal standard. Serum samples were pretreated with solid-phase extraction using Bond Elut C18 (200mg) cartridges or with direct precipitation using acetonitrile. Results: The calibration curves were linear over the range of 0.05-1.25 µg/ml for direct precipitation method and 0.5-5 µg/ml for solid-phase extraction. The mean recoveries of crocetin over a concentration range of 0.05-5 µg/ml serum for direct precipitation method and 0.5-5 µg/ml for solid-phase extraction were above 70 % and 60 %, respectively. The intraday coefficients of variation were 0.37- 2.6% for direct precipitation method and 0.64 - 5.43% for solid-phase extraction. The inter day coefficients of variation were 1.69 – 6.03% for direct precipitation method and 5.13-12.74% for solid-phase extraction, respectively. The lower limit of quantification for crocetin was 0.05 µg/ml for direct precipitation method and 0.5 µg/ml for solid-phase extraction. Conclusion: The validated direct precipitation method for HPLC satisfied all of the criteria that were necessary for a bioanalytical method and could reliably quantitate crocetin in human serum for future clinical pharmacokinetic study. PMID:23638292

Photoluminescent Metal–Organic Frameworks for Gas Sensing

PubMed Central

Lin, Rui‐Biao; Liu, Si‐Yang; Ye, Jia‐Wen; Li, Xu‐Yu

2016-01-01

Luminescence of porous coordination polymers (PCPs) or metal–organic frameworks (MOFs) is sensitive to the type and concentration of chemical species in the surrounding environment, because these materials combine the advantages of the highly regular porous structures and various luminescence mechanisms, as well as diversified host‐guest interactions. In the past few years, luminescent MOFs have attracted more and more attention for chemical sensing of gas‐phase analytes, including common gases and vapors of solids/liquids. While liquid‐phase and gas‐phase luminescence sensing by MOFs share similar mechanisms such as host‐guest electron and/or energy transfer, exiplex formation, and guest‐perturbing of excited‐state energy level and radiation pathways, via various types of host‐guest interactions, gas‐phase sensing has its unique advantages and challenges, such as easy utilization of encapsulated guest luminophores and difficulty for accurate measurement of the intensity change. This review summarizes recent progresses by using luminescent MOFs as reusable sensing materials for detection of gases and vapors of solids/liquids especially for O2, highlighting various strategies for improving the sensitivity, selectivity, stability, and accuracy, reducing the materials cost, and developing related devices. PMID:27818903

Clinical cytometry and progress in HLA antibody detection.

PubMed

Bray, Robert A; Tarsitani, Christine; Gebel, Howard M; Lee, Jar-How

2011-01-01

For most solid organ and selected stem cell transplants, antibodies against mismatched HLA antigens can lead to early and late graft failure. In recognition of the clinical significance of these antibodies, HLA antibody identification is one of the most critical functions of histocompatibility laboratories. Early methods employed cumbersome and insensitive complement-dependent cytotoxicity assays with a visual read-out. A little over 20 years ago flow cytometry entered the realm of antibody detection with the introduction of the flow cytometric crossmatch. Cytometry's increased sensitivity and objectivity quickly earned it popularity as a preferred crossmatch method especially for sensitized recipients. Although a sensitive method, the flow crossmatch was criticized as being "too sensitive" as false positive reactions were a know drawback. In part, the shortcomings of the flow crossmatch were due to the lack of corresponding sensitive and specific HLA antibody screening assays. However, in the mid 1990s, solid phase assays, capable of utilizing standard flow cytometers, were developed. These assays used microparticles coated with purified HLA molecules. Hence, the era of solid-phase, microparticle technology for HLA antibody detection was born permitting the sensitive and specific detection of HLA antibody. It was now possible to provide better correlation between HLA antibody detection and the flow cytometric crossmatch. This flow-based technology was soon followed by adaptation to the Luminex platform permitting a mutltiplexed approach for the identification and characterization of HLA antibodies. It is hoped that these technologies will ultimately lead to the identification of parameters that best correlate with and/or predict transplant outcomes. Copyright © 2011 Elsevier Inc. All rights reserved.

Ligand-Sensitized Lanthanide Nanocrystals: Merging Solid-State Photophysics and Molecular Solution Chemistry

DOE PAGES

Agbo, Peter; Abergel, Rebecca J.

2016-06-30

To date, the breadth of scientific research that has been devoted to investigating the photochemical and photophysical behavior of the lanthanide elements has generally fallen into one of two camps: solution studies of luminescent lanthanide metal-ligand complexes or investigations of solid-state nanoparticles, composed primarily of, or doped with, lanthan ide lumiphores. In the latter case, most research of lanthanide nanocolloids has precluded any investigations regarding the use of organic ligands to overcome the difficulties associated with f-f excitation of lanthanides. Instead, most work on condensed-phase lanthanide luminescence has centered on strategies such as d-f charge separation in divalent lanthanides andmore » the sensitization of lanthanide excited states using quantum dots. Current work now aims at bridging the camps of condensed-phase lanthanide photophysics and the solution chemistry of ligand-lanthanide molecular complexes. Some recent efforts have partly focused on the fundamental characterization of NaGd 1-x Ln x F 4 nanoparticles featuring surface display of the sensitizer ligand 3,4,3-LI(1,2-HOPO), showing these structures to be capable of converting absorbed UV light into luminescence from Eu 3+ and Tb 3+ ions. Our results suggest such a use of the ligand sensitization as a tool of choice to overcome the constraints of UV solar spectrum/semiconductor band-gap mismatch and low absorption cross sections in solid-state lanthanide systems.« less

Solid-Phase Microextraction Coupled to Capillary Atmospheric Pressure Photoionization-Mass Spectrometry for Direct Analysis of Polar and Nonpolar Compounds.

PubMed

Mirabelli, Mario F; Zenobi, Renato

2018-04-17

A novel capillary ionization source based on atmospheric pressure photoionization (cAPPI) was developed and used for the direct interfacing between solid-phase microextraction (SPME) and mass spectrometry (MS). The efficiency of the source was evaluated for direct and dopant-assisted photoionization, analyzing both polar (e.g., triazines and organophosphorus pesticides) and nonpolar (polycyclic aromatic hydrocarbons, PAHs) compounds. The results show that the range of compound polarity, which can be addressed by direct SPME-MS can be substantially extended by using cAPPI, compared to other sensitive techniques like direct analysis in real time (DART) and dielectric barrier discharge ionization (DBDI). The new source delivers a very high sensitivity, down to sub parts-per-trillion (ppt), making it a viable alternative when compared to previously reported and less comprehensive direct approaches.

Sensitive determination of RDX, nitroso-RDX metabolites, and other munitions in ground water by solid-phase extraction and isotope dilution liquid chromatography-atmospheric pressure electro-spray [correction of chemical] ionization mass spectrometry.

PubMed

Cassada, D A; Monson, S J; Snow, D D; Spalding, R F

1999-06-04

Recent improvements in the LC-MS interface have increased the sensitivity and selectivity of this instrument in the analysis of polar and thermally-labile aqueous constituents. Determination of RDX, nitroso-RDX metabolites, and other munitions was enhanced using LC-MS with solid-phase extraction, 15N3-RDX internal standard, and electrospray ionization (ESI) in negative ion mode. ESI produced a five-fold increase in detector response over atmospheric pressure chemical ionization (APCI) for the nitramine compounds, while the more energetic APCI produced more than twenty times the ESI response for nitroaromatics. Method detection limits in ESI for nitramines varied from 0.03 microgram l-1 for MNX to 0.05 microgram l-1 for RDX.

[Simultaneous determination of 15 industrial synthetic dyes in condiment by solid phase extraction-high performance liquid chromatography].

PubMed

Liu, Min; Li, Xiaolin; Bie, Wei; Wang, Minglin; Feng, Qian

2011-02-01

A new method was established for the determination of 15 industrial synthetic dyes in condiment by solid phase extraction-high performance liquid chromatography (SPE-HPLC). The samples were extracted by methanol-water (1:1, v/v) and purified by a solid phase extraction column. Then, the chromatographic separation was achieved on a Luna C18 column by linear gradient elution. The mobile phase was 10 mmol/L ammonium acetate-acetonitrile (containing 1% acetic acid). The results showed that the 15 industrial synthetic dyes can be separated efficiently. The recoveries of the 15 industrial synthetic dyes spiked in condiment were between 84.6% and 114.2% with the relative standard deviations of 0.9% - 10.3%. The limits of detection of this method was 0.05 - 0.18 mg/kg for the 15 industrial synthetic dyes. The method is simple, sensitive, accurate, repeatable and can be used for simultaneous determination of the 15 illegally added industrial synthetic dyes.

Detection of HLA Antibodies in Organ Transplant Recipients – Triumphs and Challenges of the Solid Phase Bead Assay

PubMed Central

Tait, Brian D.

2016-01-01

This review outlines the development of human leukocyte antigen (HLA) antibody detection assays and their use in organ transplantation in both antibody screening and crossmatching. The development of sensitive solid phase assays such as the enzyme-linked immunosorbent assay technique, and in particular the bead-based technology has revolutionized this field over the last 10–15 years. This revolution however has created a new paradigm in clinical decision making with respect to the detection of low level pretransplant HLA sensitization and its clinical relevance. The relative sensitivities of the assays used are discussed and the relevance of conflicting inter-assay results. Each assay has its advantages and disadvantages and these are discussed. Over the last decade, the bead-based assay utilizing the Luminex® fluorocytometer instrument has become established as the “gold standard” for HLA antibody testing. However, there are still unresolved issues surrounding this technique, such as the presence of denatured HLA molecules on the beads which reveal cryptic epitopes and the issue of appropriate fluorescence cut off values for positivity. The assay has been modified to detect complement binding (CB) in addition to non-complement binding (NCB) HLA antibodies although the clinical relevance of the CB and NCB IgG isotypes is not fully resolved. The increase sensitivity of the Luminex® bead assay over the complement-dependent cytotoxicity crossmatch has permitted the concept of the “virtual crossmatch” whereby the crossmatch is predicted to a high degree of accuracy based on the HLA antibody specificities detected by the solid phase assay. Dialog between clinicians and laboratory staff on an individual patient basis is essential for correct clinical decision making based on HLA antibody results obtained by the various techniques. PMID:28018342

Temperature-Controlled High-Speed AFM: Real-Time Observation of Ripple Phase Transitions.

PubMed

Takahashi, Hirohide; Miyagi, Atsushi; Redondo-Morata, Lorena; Scheuring, Simon

2016-11-01

With nanometer lateral and Angstrom vertical resolution, atomic force microscopy (AFM) has contributed unique data improving the understanding of lipid bilayers. Lipid bilayers are found in several different temperature-dependent states, termed phases; the main phases are solid and fluid phases. The transition temperature between solid and fluid phases is lipid composition specific. Under certain conditions some lipid bilayers adopt a so-called ripple phase, a structure where solid and fluid phase domains alternate with constant periodicity. Because of its narrow regime of existence and heterogeneity ripple phase and its transition dynamics remain poorly understood. Here, a temperature control device to high-speed atomic force microscopy (HS-AFM) to observe dynamics of phase transition from ripple phase to fluid phase reversibly in real time is developed and integrated. Based on HS-AFM imaging, the phase transition processes from ripple phase to fluid phase and from ripple phase to metastable ripple phase to fluid phase could be reversibly, phenomenologically, and quantitatively studied. The results here show phase transition hysteresis in fast cooling and heating processes, while both melting and condensation occur at 24.15 °C in quasi-steady state situation. A second metastable ripple phase with larger periodicity is formed at the ripple phase to fluid phase transition when the buffer contains Ca 2+ . The presented temperature-controlled HS-AFM is a new unique experimental system to observe dynamics of temperature-sensitive processes at the nanoscopic level. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sequential, solid-phase assay for biotin in physiologic fluids that correlates with expected biotin status

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

Mock, D.M.; DuBois, D.B.

1986-03-01

Interest in accurate measurement of biotin concentrations in plasma and urine has been stimulated by recent advances in the understanding of biotin-responsive inborn errors of metabolism and by several reports describing acquired biotin deficiency during parenteral alimentation. This paper presents a biotin assay utilizing radiolabeled avidin in a sequential, solid-phase method; the assay has increased sensitivity compared to previous methods (greater than or equal to 10 fmol/tube), correlates with expected trends in biotin concentrations in blood and urine in a rat model of biotin deficiency, and can utilize commercially available radiolabeled avidin.

[Improvement of the determination method of benzene, toluene, ethylbenzene and xylene(BTEX) in water using activated carbon fiber solid-phase microextraction/gas chromatography-mass spectrometry(GC-MS)].

PubMed

Jia, Jin-ping; Feng, Xue; Fang, Neng-hu; Huang, Jia-liang

2002-01-01

The methods of direct injection, carbon disulfide extraction and activated carbon fiber solid-phase microextraction/GC-MS, usually used in the determination of BTEX in water matrix, are compared and discussed. Experimental data of linearity, precision and limit of detection illustrate that the last one is better than the two other methods. This method was tested by the practical sample experiments and expected to be a simple and sensitive new method for the analysis of BTEX in water.

Rapid solid-phase immunoassay for 6-keto prostaglandin F1 alpha on microplates

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

Schramm, W.; Smith, R.H.; Jackson, T.M.

1990-03-01

We describe, for the measurement of 6-keto prostaglandin F1 alpha in biological media, a solid-phase immunoassay with immobilized antibodies that requires a total processing time of less than 2 h with hands-on time less than 30 min for 40 samples. The method combines the convenience of the microplate format with the sensitivity of radiolabeled prostaglandin derivatives as tracers in a competitive immunoassay. The intra- and interassay variations at 50% displacement of the radiolabeled prostaglandin derivative as tracer were 9.0% and 11.8%, respectively. At 50% displacement of the radiolabeled tracer, the sensitivity is about 20 pg per well. Optimal incubation timemore » is between 60 and 90 min. Nonspecific binding was less than 1% if about 8 pg of tracer (approximately 25,000 counts/min per well) was used. Inhibition curves of samples in different dilutions were parallel to standard curves. The variation of bound radiolabeled prostaglandin derivative within the wells of one microplate (n = 96) was less than 3%. Human plasma samples and medium from tissue culture assayed for 6-keto prostaglandin F1 alpha correlated well with results obtained with a solid-phase assay based on use of magnetic particles (r = 0.99, n = 24) for culture-medium samples; r = 0.99; n = 26 for plasma samples.« less

Preparation and application of a polythiophene solid-phase microextraction fiber for the determination of endocrine-disruptor pesticides in well waters.

PubMed

Pelit, Levent; Dizdaş, Tuğberk Nail

2013-10-01

A robust solid-phase microextraction fiber was fabricated by electropolymerization of thiophene on a stainless steel wire. This fiber was applied for the determination of endocrine-disruptor pesticides, namely, chlorpyrifos, penconazole, procymidone, bromopropylate, and λ-cyhalothrin in well waters by a headspace solid-phase microextraction procedure. Operational parameters, namely, pH, sample volume, adsorption temperature and time, desorption temperature, stirring rate, and salt amount were optimized as 7.0, 8 mL, 70°C and 20 min, 250°C, 600 rpm, and 0.3 g/mL, respectively. The separation power of GC was coupled with the excellent sensitivity of the developed fiber enabling us to determine pesticide mixtures simultaneously in a ng/mL range. The LOD was in the range of 0.02-0.64 ng/mL. The method was successfully applied for the selective and sensitive determination of target pesticides in well water samples with acceptable recovery values (92-110%). The polythiophene fiber gives satisfactory results compared with commercial fibers. Commonly used pesticides with different polarities were chosen as representative compounds to search the applicability of the fiber for well water analysis collected from vineyards. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of transition dipole phase on high-order-harmonic generation in solid materials

NASA Astrophysics Data System (ADS)

Jiang, Shicheng; Wei, Hui; Chen, Jigen; Yu, Chao; Lu, Ruifeng; Lin, C. D.

2017-11-01

High-order harmonic spectra from solid materials driven by single-color multicycle laser fields sometimes contain even harmonics. In this work we attribute the appearance of even harmonics to the nonzero transition dipole phase (TDP) when the solid system has broken symmetry. By calculating the harmonic efficiency from graphene and gapped graphene by using the semiconductor Bloch equations under the tight-binding approximation, we demonstrate the role of the TDP, which has been ignored for a long time. When the crystal has inversion symmetry, or reflection symmetry with the symmetry plane perpendicular to the laser polarization direction, the TDP can be neglected. Without such symmetry, however, the TDP will lead to the appearance of even harmonics. We further show that the TDP is sensitive to the crystal geometry. To extract the structure information from the harmonic spectra of a solid the TDP cannot be ignored.

Carbon nanotube enhanced label-free detection of microRNAs based on hairpin probe triggered solid-phase rolling-circle amplification

NASA Astrophysics Data System (ADS)

Tian, Qianqian; Wang, Ying; Deng, Ruijie; Lin, Lei; Liu, Yang; Li, Jinghong

2014-12-01

The detection of microRNAs (miRNAs) is imperative for gaining a better understanding of the functions of these biomarkers and has great potential for the early diagnosis of human disease. High sensitivity and selectivity for miRNA detection brings new challenges. Herein, an ultrasensitive protocol for electrochemical detection of miRNA is designed through carbon nanotube (CNT) enhanced label-free detection based on hairpin probe triggered solid-phase rolling-circle amplification (RCA). Traditionally, RCA, widely applied for signal enhancement in the construction of a variety of biosensors, has an intrinsic limitation of ultrasensitive detection, as it is difficult to separate the enzymes, templates, and padlock DNAs from the RCA products in the homogeneous solution. We purposely designed a solid-phase RCA strategy, using CNTs as the solid substrate, integrated with a hairpin structured probe to recognize target miRNA. In the presence of miRNA the stem-loop structure will be unfolded, triggering the CNT based RCA process. Due to the efficient blocking effect originating from the polymeric RCA products, the label-free assay of miRNA exhibits an ultrasensitive detection limit of 1.2 fM. Furthermore, the protocol possesses excellent specificity for resolving lung cancer-related let-7 family members which have only one-nucleotide variations. The high sensitivity and selectivity give the method great potential for applications in online diagnostics and in situ detection in long-term development.The detection of microRNAs (miRNAs) is imperative for gaining a better understanding of the functions of these biomarkers and has great potential for the early diagnosis of human disease. High sensitivity and selectivity for miRNA detection brings new challenges. Herein, an ultrasensitive protocol for electrochemical detection of miRNA is designed through carbon nanotube (CNT) enhanced label-free detection based on hairpin probe triggered solid-phase rolling-circle amplification (RCA). Traditionally, RCA, widely applied for signal enhancement in the construction of a variety of biosensors, has an intrinsic limitation of ultrasensitive detection, as it is difficult to separate the enzymes, templates, and padlock DNAs from the RCA products in the homogeneous solution. We purposely designed a solid-phase RCA strategy, using CNTs as the solid substrate, integrated with a hairpin structured probe to recognize target miRNA. In the presence of miRNA the stem-loop structure will be unfolded, triggering the CNT based RCA process. Due to the efficient blocking effect originating from the polymeric RCA products, the label-free assay of miRNA exhibits an ultrasensitive detection limit of 1.2 fM. Furthermore, the protocol possesses excellent specificity for resolving lung cancer-related let-7 family members which have only one-nucleotide variations. The high sensitivity and selectivity give the method great potential for applications in online diagnostics and in situ detection in long-term development. Electronic supplementary information (ESI) available: Preparation of the chemically modified multi-walled carbon nanotubes (CNTs), characterization of the CNTs and modified CNTs, preparation of the circular probe, gel electrophoresis of the RCA products, and DNA probes as noted in the text. See DOI: 10.1039/c4nr05243a

Phase-sensitive terahertz spectroscopy with backward-wave oscillators in reflection mode.

PubMed

Pronin, A V; Goncharov, Yu G; Fischer, T; Wosnitza, J

2009-12-01

In this article we describe a method which allows accurate measurements of the complex reflection coefficient r = absolute value(r) x exp(i phi(R)) of a solid at frequencies of 1-50 cm(-1) (30 GHz-1.5 THz). Backward-wave oscillators are used as sources for monochromatic coherent radiation tunable in frequency. The amplitude of the complex reflection (the reflectivity) is measured in a standard way, while the phase shift, introduced by the reflection from the sample surface, is measured using a Michelson interferometer. This method is particular useful for nontransparent samples, where phase-sensitive transmission measurements are not possible. The method requires no Kramers-Kronig transformation in order to extract the sample's electrodynamic properties (such as the complex dielectric function or complex conductivity). Another area of application of this method is the study of magnetic materials with complex dynamic permeabilities different from unity at the measurement frequencies (for example, colossal-magnetoresistance materials and metamaterials). Measuring both the phase-sensitive transmission and the phase-sensitive reflection allows for a straightforward model-independent determination of the dielectric permittivity and magnetic permeability of such materials.

Phase-sensitive terahertz spectroscopy with backward-wave oscillators in reflection mode

NASA Astrophysics Data System (ADS)

Pronin, A. V.; Goncharov, Yu. G.; Fischer, T.; Wosnitza, J.

2009-12-01

In this article we describe a method which allows accurate measurements of the complex reflection coefficient r̂=|r̂|ṡexp(iφR) of a solid at frequencies of 1-50 cm-1 (30 GHz-1.5 THz). Backward-wave oscillators are used as sources for monochromatic coherent radiation tunable in frequency. The amplitude of the complex reflection (the reflectivity) is measured in a standard way, while the phase shift, introduced by the reflection from the sample surface, is measured using a Michelson interferometer. This method is particular useful for nontransparent samples, where phase-sensitive transmission measurements are not possible. The method requires no Kramers-Kronig transformation in order to extract the sample's electrodynamic properties (such as the complex dielectric function or complex conductivity). Another area of application of this method is the study of magnetic materials with complex dynamic permeabilities different from unity at the measurement frequencies (for example, colossal-magnetoresistance materials and metamaterials). Measuring both the phase-sensitive transmission and the phase-sensitive reflection allows for a straightforward model-independent determination of the dielectric permittivity and magnetic permeability of such materials.

The Albedo of Kepler's Small Worlds

NASA Astrophysics Data System (ADS)

Jansen, Tiffany; Kipping, David

2018-01-01

The study of exoplanet phase curves has been established as a powerful tool for measuring the atmospheric properties of other worlds. To first order, phase curves have the same amplitude as occultations, yet far greater temporal baselines enabling substantial improvements in sensitivity. Even so, only a relatively small fraction of Kepler planets have detectable phase curves, leading to a population dominated by hot-Jupiters. One way to boost sensitivity further is to stack different planets of similar types together, giving rise to an average phase curve for a specific ensemble. In this work, we measure the average albedo, thermal redistribution efficiency, and greenhouse boosting factor from the average phase curves of 115 Neptunian and 50 Terran (solid) worlds. We construct ensemble phase curve models for both samples accounting for the reflection and thermal components and regress our models assuming a global albedo, redistribution factor and greenhouse factor in a Bayesian framework. We find modest evidence for a detected phase curve in the Neptunian sample, although the albedo and thermal properties are somewhat degenerate meaning we can only place an upper limit on the albedo of Ag < 0.23 and greenhouse factor of f < 1.40 to 95% confidence. As predicted theoretically, this confirms hot-Neptunes are darker than Neptune and Uranus. Additionally, we place a constraint on the albedo of solid, Terran worlds of Ag < 0.42 and f < 1.60 to 95% confidence, compatible with a dark Lunar-like surface.

Solid-phase single molecule biosensing using dual-color colocalization of fluorescent quantum dot nanoprobes

NASA Astrophysics Data System (ADS)

Liu, Jianbo; Yang, Xiaohai; Wang, Kemin; Wang, Qing; Liu, Wei; Wang, Dong

2013-10-01

The development of solid-phase surface-based single molecule imaging technology has attracted significant interest during the past decades. Here we demonstrate a sandwich hybridization method for highly sensitive detection of a single thrombin protein at a solid-phase surface based on the use of dual-color colocalization of fluorescent quantum dot (QD) nanoprobes. Green QD560-modified thrombin binding aptamer I (QD560-TBA I) were deposited on a positive poly(l-lysine) assembled layer, followed by bovine serum albumin blocking. It allowed the thrombin protein to mediate the binding of the easily detectable red QD650-modified thrombin binding aptamer II (QD650-TBA II) to the QD560-TBA I substrate. Thus, the presence of the target thrombin can be determined based on fluorescent colocalization measurements of the nanoassemblies, without target amplification or probe separation. The detection limit of this assay reached 0.8 pM. This fluorescent colocalization assay has enabled single molecule recognition in a separation-free detection format, and can serve as a sensitive biosensing platform that greatly suppresses the nonspecific adsorption false-positive signal. This method can be extended to other areas such as multiplexed immunoassay, single cell analysis, and real time biomolecule interaction studies.The development of solid-phase surface-based single molecule imaging technology has attracted significant interest during the past decades. Here we demonstrate a sandwich hybridization method for highly sensitive detection of a single thrombin protein at a solid-phase surface based on the use of dual-color colocalization of fluorescent quantum dot (QD) nanoprobes. Green QD560-modified thrombin binding aptamer I (QD560-TBA I) were deposited on a positive poly(l-lysine) assembled layer, followed by bovine serum albumin blocking. It allowed the thrombin protein to mediate the binding of the easily detectable red QD650-modified thrombin binding aptamer II (QD650-TBA II) to the QD560-TBA I substrate. Thus, the presence of the target thrombin can be determined based on fluorescent colocalization measurements of the nanoassemblies, without target amplification or probe separation. The detection limit of this assay reached 0.8 pM. This fluorescent colocalization assay has enabled single molecule recognition in a separation-free detection format, and can serve as a sensitive biosensing platform that greatly suppresses the nonspecific adsorption false-positive signal. This method can be extended to other areas such as multiplexed immunoassay, single cell analysis, and real time biomolecule interaction studies. Electronic supplementary information (ESI) available: Absorbance and fluorescence spectra of quantum dot nanoprobes, electrophoresis analysis, and experimental setup for fluorescence imaging with dual channels. See DOI: 10.1039/c3nr03291d

The Effect of Molecular Orientation to Solid-Solid and Melting Transitions

NASA Astrophysics Data System (ADS)

Yazici, Mustafa; Özgan, Şükrü

The thermodynamics of solid-solid and solid-liquid transitions are investigated with an account of the number of molecular orientation. The variations of the positional and orientational orders with the reduced temperature are studied. It is found out that orientational order parameter is very sensitive to the number of allowed orientation. The reduced transition temperatures, volume changes and entropy changes of the phase transitions and theoretical phase diagrams are obtained. The entropy changes of melting transitions for different numbers of allowed orientation of the present model are compared with the theoretical results and some experimental data. The quantitative predictions of the model are compared with experimental results for plastic crystals and agreement between predictions of the model and the experimental results are approximately good. Also, different numbers of allowed orientation D correspond to different experimental results HI, HBr, H2S for D = 2; HBr, CCl4, HI for D = 4; C2H12 for D = 6; CH4, PH3 for D = 20.

Effect of Strengthening Mechanism on Strain-Rate Related Tensile Properties of Low-Carbon Sheet Steels for Automotive Application

NASA Astrophysics Data System (ADS)

Das, Anindya; Biswas, Pinaki; Tarafder, S.; Chakrabarti, D.; Sivaprasad, S.

2018-05-01

In order to ensure crash resistance of the steels used in automotive components, the ensile deformation behavior needs to be studied and predicted not only under quasi-static condition, but also under dynamic loading rates. In the present study, tensile tests have been performed on four different automobile grade sheet steels, namely interstitial free steel, dual-phase 600 and 800, and a carbon manganese steel over the strain rate regime of 0.001-800/s. Apart from the variation in strength (which always increased with strain rate), the effect of strengthening mechanism on strain rate sensitivity and strain hardening behavior has been evaluated. Strain rate sensitivity was found to increase at high-strain rate regime for all the steels. Contribution of solid solution hardening on strain rate sensitivity at lower plastic strains was found to be higher compared to dislocation strengthening and second-phase hardening. However, precipitation hardening coupled with solid solution hardening produced the highest strain rate sensitivity, in C-Mn-440 steel at high strain rates. Different strain-rate-sensitive models which take into account the change in yield stress and strain hardening behavior with strain rate for ductile materials were used to predict the flow behavior of these sheet steels at strain rates up to 800/s.

Evidence of two-stage melting of Wigner solids

NASA Astrophysics Data System (ADS)

Knighton, Talbot; Wu, Zhe; Huang, Jian; Serafin, Alessandro; Xia, J. S.; Pfeiffer, L. N.; West, K. W.

2018-02-01

Ultralow carrier concentrations of two-dimensional holes down to p =1 ×109cm-2 are realized. Remarkable insulating states are found below a critical density of pc=4 ×109cm-2 or rs≈40 . Sensitive dc V-I measurement as a function of temperature and electric field reveals a two-stage phase transition supporting the melting of a Wigner solid as a two-stage first-order transition.

Rapid and sensitive analysis of phthalate metabolites, bisphenol A, and endogenous steroid hormones in human urine by mixed-mode solid-phase extraction, dansylation, and ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry.

PubMed

Wang, He-xing; Wang, Bin; Zhou, Ying; Jiang, Qing-wu

2013-05-01

Steroid hormone levels in human urine are convenient and sensitive indicators for the impact of phthalates and/or bisphenol A (BPA) exposure on the human steroid hormone endocrine system. In this study, a rapid and sensitive method for determination of 14 phthalate metabolites, BPA, and ten endogenous steroid hormones in urine was developed and validated on the basis of ultra-performance liquid chromatography coupled with electrospray ionization triple quadrupole mass spectrometry. The optimized mixed-mode solid phase-extraction separated the weakly acidic or neutral BPA and steroid hormones from acidic phthalate metabolites in urine: the former were determined in positive ion mode with a methanol/water mobile phase containing 10 mM ammonium formate; the latter were determined in negative ion mode with a acetonitrile/water mobile phase containing 0.1 % acetic acid, which significantly alleviated matrix effects for the analysis of BPA and steroid hormones. Dansylation of estrogens and BPA realized simultaneous and sensitive analysis of the endogenous steroid hormones and BPA in a single chromatographic run. The limits of detection were less than 0.84 ng/mL for phthalate metabolites and less than 0.22 ng/mL for endogenous steroid hormones and BPA. This proposed method had satisfactory precision and accuracy, and was successfully applied to the analyses of human urine samples. This method could be valuable when investigating the associations among endocrine-disrupting chemicals, endogenous steroid hormones, and relevant adverse outcomes in epidemiological studies.

A simplified radiometabolite analysis procedure for PET radioligands using a solid phase extraction with micellar medium.

PubMed

Nakao, Ryuji; Halldin, Christer

2013-07-01

A solid phase extraction method has been developed for simple and high-speed direct determination of PET radioligands in plasma. This methodology makes use of a micellar medium and a solid-phase extraction cartridge for displacement of plasma protein bound radioligand and separation of PET radioligands from their radiometabolites without significant preparation. The plasma samples taken from monkey or human during PET measurements were mixed with a micellar eluent containing an anionic surfactant sodium dodecyl sulphate and loaded onto SPE cartridges. The amount of radioactivity corresponding to parent radioligand (retained on the cartridge) and its radioactive metabolites (eluted with micellar eluent) was measured. Under the optimized conditions, excellent separation of target PET radioligands from their radiometabolites was achieved with a single elution and short run-time of 1 min. This method was successfully applied to study the metabolism for (11)C-labelled radioligands in human or monkey plasma. The amount of parent PET radioligands estimated by micellar solid phase extraction strongly corresponded with that determined by radio-LC. The improved throughput permitted the analysis of a large number of plasma samples (up to 13 samples per one PET study) for accurate estimation of metabolite-corrected input function during quantitative PET imaging studies. Solid phase extraction together with micellar medium is fast, sensitive and easy to use, and therefore it is an attractive alternative method to determine relative composition of PET radioligands in plasma. Copyright © 2013 Elsevier Inc. All rights reserved.

Solid-phase reductive amination for glycomic analysis.

PubMed

Jiang, Kuan; Zhu, He; Xiao, Cong; Liu, Ding; Edmunds, Garrett; Wen, Liuqing; Ma, Cheng; Li, Jing; Wang, Peng George

2017-04-15

Reductive amination is an indispensable method for glycomic analysis, as it tremendously facilitates glycan characterization and quantification by coupling functional tags at the reducing ends of glycans. However, traditional in-solution derivatization based approach for the preparation of reductively aminated glycans is quite tedious and time-consuming. Here, a simpler and more efficient strategy termed solid-phase reductive amination was investigated. The general concept underlying this new approach is to streamline glycan extraction, derivatization, and purification on non-porous graphitized carbon sorbents. Neutral and sialylated standard glycans were utilized to test the feasibility of the solid-phase method. As results, almost complete labeling of those glycans with four common labels of aniline, 2-aminobenzamide (2-AB), 2-aminobenzoic acid (2-AA) and 2-amino-N-(2-aminoethyl)-benzamide (AEAB) was obtained, and negligible desialylation occurred during sample preparation. The labeled glycans derived from glycoproteins showed excellent reproducibility in high performance liquid chromatography (HPLC) and matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis. Direct comparisons based on fluorescent absorbance and relative quantification using isotopic labeling demonstrated that the solid-phase strategy enabled 20-30% increase in sample recovery. In short, the solid-phase strategy is simple, reproducible, efficient, and sensitive for glycan analysis. This method was also successfully applied for N-glycan profiling of HEK 293 cells with MALDI-TOF MS, showing its attractive application in the high-throughput analysis of mammalian glycome. Published by Elsevier B.V.

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

Chen, S.-S.; IGE Therapeutics, Inc., Cellular and Cancer Immunology, 6370 Lusk Boulevard, F109, San Diego, CA 92121; Yang Yongmin

GFP-C{kappa} fusion protein was previously shown selectable on ribosome display platform with solid phase antibodies against GFP determinant [Y.-M. Yang, T.J. Barankiewicz, M. He, M. Taussig, S.-S. Chen, Selection of antigenic markers on a GFP-C{kappa} fusion scaffold with high sensitivity by eukaryotic ribosome display, Biochem. Biophys. Res. Commun. 359 (2007) 251-257]. Herein, we show that members of aptameric peptide library constructed within the site 6 and site 8/9 loops of GFP of the ribosome display construct are selectable upon binding to the solid phase IgE antigen. An input of 1.0 {mu}g of the dual site aptameric GFP library exhibiting amore » diversity of 7.5 x 10{sup 11} was transcribed, translated and incubated with solid phase IgE. RT-PCR products were amplified from mRNA of the aptamer-ribosome-mRNA (ARM) complex captured on the solid phase IgE. Clones of aptameric GFP were prepared from RT-PCR product of ARM complex following repetitive selection. Recombinant aptameric GFP proteins from the selected clones bind IgE coated on the 96-well plate, and the binding was abrogated by incubation with soluble human IgE but not human IgG. Selected aptameric GFP proteins also exhibit binding to three different sources of human IgE (IgE PS, BED, and JW8) but not irrelevant proteins. These observations indicate that appropriately selected aptameric GFP on a solid phase ligand by ribosome display may serve as an affinity reagent for blocking reactivity of a biological ligand.« less

Attosecond control of electrons emitted from a nanoscale metal tip.

PubMed

Krüger, Michael; Schenk, Markus; Hommelhoff, Peter

2011-07-06

Attosecond science is based on steering electrons with the electric field of well controlled femtosecond laser pulses. It has led to the generation of extreme-ultraviolet pulses with a duration of less than 100 attoseconds (ref. 3; 1 as = 10(-18) s), to the measurement of intramolecular dynamics (by diffraction of an electron taken from the molecule under scrutiny) and to ultrafast electron holography. All these effects have been observed with atoms or molecules in the gas phase. Electrons liberated from solids by few-cycle laser pulses are also predicted to show a strong light-phase sensitivity, but only very small effects have been observed. Here we report that the spectra of electrons undergoing photoemission from a nanometre-scale tungsten tip show a dependence on the carrier-envelope phase of the laser, with a current modulation of up to 100 per cent. Depending on the carrier-envelope phase, electrons are emitted either from a single sub-500-attosecond interval of the 6-femtosecond laser pulse, or from two such intervals; the latter case leads to spectral interference. We also show that coherent elastic re-scattering of liberated electrons takes place at the metal surface. Owing to field enhancement at the tip, a simple laser oscillator reaches the peak electric field strengths required for attosecond experiments at 100-megahertz repetition rates, rendering complex amplified laser systems dispensable. Practically, this work represents a simple, extremely sensitive carrier-envelope phase sensor, which could be shrunk in volume to about one cubic centimetre. Our results indicate that the attosecond techniques developed with (and for) atoms and molecules can also be used with solids. In particular, we foresee subfemtosecond, subnanometre probing of collective electron dynamics (such as plasmon polaritons) in solid-state systems ranging in scale from mesoscopic solids to clusters and to single protruding atoms. ©2011 Macmillan Publishers Limited. All rights reserved

Pressure-induced fcc to hcp phase transition in Ni-based high entropy solid solution alloys

DOE PAGES

Zhang, Fuxiang; Zhao, Shijun; Jin, Ke; ...

2017-01-04

In this research, pressure-induced phase transition from the fcc to a hexagonal close-packed (hcp) structure wasfound in NiCoCrFe solid solution alloy starting at 13.5 GPa. The phase transition is very sluggish and the transition did not complete at ~ 40 GPa. The hcp structure is quenchable to ambient pressure. Only a very small amount (<5%) of hcp phase was found in the isostructural NiCoCr ternary alloy up to the pressure of 45 GPa and no obvious hcp phase was found in NiCoCrFePd system till to 74 GPa. Ab initio Gibbs free energy calculations indicated the energy differences between the fccmore » and the hcp phases for the three alloys are very small, but they are sensitive to temperature. Finally, the critical transition pressure in NiCoCrFe varies from 1 GPa at room temperature to 6 GPa at 500 K.« less

Pressure-induced fcc to hcp phase transition in Ni-based high entropy solid solution alloys

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

Zhang, F. X.; Zhao, Shijun; Jin, Ke

2017-01-04

A pressure-induced phase transition from the fcc to a hexagonal close-packed (hcp) structure was found in NiCoCrFe solid solution alloy starting at 13.5 GPa. The phase transition is very sluggish and the transition did not complete at ~40 GPa. The hcp structure is quenchable to ambient pressure. Only a very small amount (<5%) of hcp phase was found in the isostructural NiCoCr ternary alloy up to the pressure of 45 GPa and no obvious hcp phase was found in NiCoCrFePd system till to 74 GPa. Ab initio Gibbs free energy calculations indicated the energy differences between the fcc and themore » hcp phases for the three alloys are very small, but they are sensitive to temperature. The critical transition pressure in NiCoCrFe varies from ~1 GPa at room temperature to ~6 GPa at 500 K.« less

[Study on solid phase extraction spectrophotometric determination of zinc with 2-(2-quinolylazo)-5-dimthylaminophenol].

PubMed

Zhou, Shi-ping; Duan, Chang-qun; Liu, Hong-cheng; Hu, Qiu-fen

2005-10-01

A highly sensitive, selective and rapid method for the determination of zinc based on the rapid reaction of zinc(II) with 2-(2-quinolylazo)-5-dimthylaminophenol (QADMAP) and the solid phase extraction of zinc ion with anion exchange resin cartridge was developed. In the presence of pH 8.5 buffer solution and Triton X-100 medium, QADMAP can react with zinc(II) to form a stable 2 :1 complex (QADMAP:Zn(II)). The molar absorptivity is 1.22 x 10(5)L x moL(-1) x cm(-1) at 590 nm. Beer's law is obeyed in the range of 0-1.0 microg x mL(-1). The zinc ions in the samples can be enriched and separated by solid phase extraction with anion exchange resincartridge. Testing results show that recovery for zinc(II) was from 95% to 104%, and RSD was below 3%. This method was applied to the determination of zinc in water and food with good results.

Simultaneous detection of seventeen drugs of abuse and metabolites in hair using solid phase micro extraction (SPME) with GC/MS.

PubMed

Aleksa, Katarina; Walasek, Paula; Fulga, Netta; Kapur, Bhushan; Gareri, Joey; Koren, Gideon

2012-05-10

The analysis of pediatric and adult hair is a useful non-invasive biomarker to effectively detect long term exposure to various xenobiotics, specifically drugs of abuse such as cocaine, opiates and amphetamines. Very often individuals are using, or are exposed to multiple drugs simultaneously and therefore it is important to be able to detect them in the same analysis. We have developed a sensitive and specific solid phase micro extraction (SPME) coupled with gas chromatography mass spectrometry (GC/MS) to detect 17 different analytes in hair using a single extraction method. Five milligrams of hair is extracted overnight, subjected to solid phase extraction (SPE) and then to SPME-GC/MS. The aimed analytes include amphetamine, methamphetamine, MDA, MDMA, cocaine, benzoylecognine, norcocaine, cocaethylene, methadone, codeine, morphine, 6-AM, oxycodone, oxymorphone, hydrocodone, hydromorphone and meperidone. The following are the LOD of the various drugs: 0.2ng/mg hair for amphetamine, methamphetamine, MDA, MDMA, morphine, codeine, 6-AM, oxycodone, oxymorphone, hydromorphone, hydrocodone, meperidine and 0.13ng/mg hair for cocaine, benzoylecognine, cocaethylene, norcocaine and methadone. This GC/MS method is sensitive and specific to detect the presence of these 17 analytes in as little as 5mg of hair and is especially useful for newborn and child hair analysis where the amount of hair is often very limited. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Benefit of computer-aided detection analysis for the detection of subsolid and solid lung nodules on thin- and thick-section CT.

PubMed

Godoy, Myrna C B; Kim, Tae Jung; White, Charles S; Bogoni, Luca; de Groot, Patricia; Florin, Charles; Obuchowski, Nancy; Babb, James S; Salganicoff, Marcos; Naidich, David P; Anand, Vikram; Park, Sangmin; Vlahos, Ioannis; Ko, Jane P

2013-01-01

The objective of our study was to evaluate the impact of computer-aided detection (CAD) on the identification of subsolid and solid lung nodules on thin- and thick-section CT. For 46 chest CT examinations with ground-glass opacity (GGO) nodules, CAD marks computed using thin data were evaluated in two phases. First, four chest radiologists reviewed thin sections (reader(thin)) for nodules and subsequently CAD marks (reader(thin) + CAD(thin)). After 4 months, the same cases were reviewed on thick sections (reader(thick)) and subsequently with CAD marks (reader(thick) + CAD(thick)). Sensitivities were evaluated. Additionally, reader(thick) sensitivity with assessment of CAD marks on thin sections was estimated (reader(thick) + CAD(thin)). For 155 nodules (mean, 5.5 mm; range, 4.0-27.5 mm)-74 solid nodules, 22 part-solid (part-solid nodules), and 59 GGO nodules-CAD stand-alone sensitivity was 80%, 95%, and 71%, respectively, with three false-positives on average (0-12) per CT study. Reader(thin) + CAD(thin) sensitivities were higher than reader(thin) for solid nodules (82% vs 57%, p < 0.001), part-solid nodules (97% vs 81%, p = 0.0027), and GGO nodules (82% vs 69%, p < 0.001) for all readers (p < 0.001). Respective sensitivities for reader(thick), reader(thick) + CAD(thick), reader(thick) + CAD(thin) were 40%, 58% (p < 0.001), and 77% (p < 0.001) for solid nodules; 72%, 73% (p = 0.322), and 94% (p < 0.001) for part-solid nodules; and 53%, 58% (p = 0.008), and 79% (p < 0.001) for GGO nodules. For reader(thin), false-positives increased from 0.64 per case to 0.90 with CAD(thin) (p < 0.001) but not for reader(thick); false-positive rates were 1.17, 1.19, and 1.26 per case for reader(thick), reader(thick) + CAD(thick), and reader(thick) + CAD(thin), respectively. Detection of GGO nodules and solid nodules is significantly improved with CAD. When interpretation is performed on thick sections, the benefit is greater when CAD marks are reviewed on thin rather than thick sections.

Control of composition and crystallinity in hydroxyapatite films deposited by electron cyclotron resonance plasma sputtering

NASA Astrophysics Data System (ADS)

Akazawa, Housei; Ueno, Yuko

2014-01-01

Hydroxyapatite (HAp) films were deposited by electron cyclotron resonance plasma sputtering under a simultaneous flow of H2O vapor gas. Crystallization during sputter-deposition at elevated temperatures and solid-phase crystallization of amorphous films were compared in terms of film properties. When HAp films were deposited with Ar sputtering gas at temperatures above 460 °C, CaO byproducts precipitated with HAp crystallites. Using Xe instead of Ar resolved the compositional problem, yielding a single HAp phase. Preferentially c-axis-oriented HAp films were obtained at substrate temperatures between 460 and 500 °C and H2O pressures higher than 1×10-2 Pa. The absorption signal of the asymmetric stretching mode of the PO43- unit (ν3) in the Fourier-transform infrared absorption (FT-IR) spectra was the narrowest for films as-crystallized during deposition with Xe, but widest for solid-phase crystallized films. While the symmetric stretching mode of PO43- (ν1) is theoretically IR-inactive, this signal emerged in the FT-IR spectra of solid-phase crystallized films, but was absent for as-crystallized films, indicating superior crystallinity for the latter. The Raman scattering signal corresponding to ν1 PO43- sensitively reflected this crystallinity. The surface hardness of as-crystallized films evaluated by a pencil hardness test was higher than that of solid-phase crystallized films.

A Phase Separation Route to Synthesize α-Fe2O3 Porous Nanofibers via Electrospinning for Ultrafast Ethanol Sensing

NASA Astrophysics Data System (ADS)

Dong, Shuwen; Yan, Shuang; Gao, Wenyuan; Liu, Guishan; Hao, Hongshun

2018-07-01

A facile and economic procedure was provided to synthesize α-Fe2O3 nanofibers. In this procedure, porous α-Fe2O3 nanofibers were obtained by a single-polymer/binary-solvent system, while solid α-Fe2O3 nanofibers were prepared by a single-polymer/single-solvent system. The crystal structure and morphology of both samples were characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption/desorption isotherms. The formation mechanism of porous structure was based on solvent evaporation-induced phase separation by the use of mixed solvents with different volatility. Furthermore, ethanol-sensing performance of the porous α-Fe2O3 nanofibers was evaluated and compared with solid α-Fe2O3 nanofibers. Results from gas-sensing measurements reveal that porous α-Fe2O3 nanofibers exhibit higher sensitivity and slightly longer recovery time than solid α-Fe2O3 nanofibers. Over all, the gas sensor based on porous α-Fe2O3 nanofibers shows excellent ethanol-sensing capability with high sensitivity and ultrafast response/recovery behaviors, indicating its potential application as a real-time monitoring gas sensor.

A Phase Separation Route to Synthesize α-Fe2O3 Porous Nanofibers via Electrospinning for Ultrafast Ethanol Sensing

NASA Astrophysics Data System (ADS)

Dong, Shuwen; Yan, Shuang; Gao, Wenyuan; Liu, Guishan; Hao, Hongshun

2018-04-01

A facile and economic procedure was provided to synthesize α-Fe2O3 nanofibers. In this procedure, porous α-Fe2O3 nanofibers were obtained by a single-polymer/binary-solvent system, while solid α-Fe2O3 nanofibers were prepared by a single-polymer/single-solvent system. The crystal structure and morphology of both samples were characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption/desorption isotherms. The formation mechanism of porous structure was based on solvent evaporation-induced phase separation by the use of mixed solvents with different volatility. Furthermore, ethanol-sensing performance of the porous α-Fe2O3 nanofibers was evaluated and compared with solid α-Fe2O3 nanofibers. Results from gas-sensing measurements reveal that porous α-Fe2O3 nanofibers exhibit higher sensitivity and slightly longer recovery time than solid α-Fe2O3 nanofibers. Over all, the gas sensor based on porous α-Fe2O3 nanofibers shows excellent ethanol-sensing capability with high sensitivity and ultrafast response/recovery behaviors, indicating its potential application as a real-time monitoring gas sensor.

Flexibility transition and guest-driven reconstruction in a ferroelastic metal-organic framework†Electronic supplementary information (ESI) available: Atomic coordinates and lattice parameter data. CCDC 1016797. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4ce01572jClick here for additional data file.

PubMed

Hunt, Sarah J; Cliffe, Matthew J; Hill, Joshua A; Cairns, Andrew B; Funnell, Nicholas P; Goodwin, Andrew L

2015-01-14

The metal-organic framework copper(i) tricyanomethanide, Cu(tcm), undergoes a ferroelastic transition on cooling below T f = 240 K. Thermal expansion measurements reveal an order-of-magnitude variation in framework flexibility across T f . The low-temperature phase α-Cu(tcm) exhibits colossal positive and negative thermal expansion that is the strongest ever reported for a framework material. On exposure to acetonitrile, Cu(tcm) undergoes a reconstructive solid-phase transition to acetonitrilocopper(i) tricyanomethanide. This transition can be reversed by heating under vacuum. Infrared spectroscopy measurements are sensitive to the phase change, suggesting that Cu(tcm) may find application in solid-phase acetonitrile sensing.

Geochemical, mineralogical and microbiological characteristics of sediment from a naturally reduced zone in a uranium-contaminated aquife

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

Campbell, K M; K Kukkadapu, R K; Qafoku, N P

2012-05-23

Localized zones or lenses of naturally reduced sediments have the potential to play a significant role in the fate and transport of redox-sensitive metals and metalloids in aquifers. To assess the mineralogy, microbiology and redox processes that occur in these zones, several cores from a region of naturally occurring reducing conditions in a U-contaminated aquifer (Rifle, CO) were examined. Sediment samples from a transect of cores ranging from oxic/suboxic Rifle aquifer sediment to naturally reduced sediment were analyzed for U and Fe content, oxidation state, and mineralogy; reduced S phases; and solid-phase organic C content using a suite of analyticalmore » and spectroscopic techniques on bulk sediment and size fractions. Solid-phase U concentrations were higher in the naturally reduced zone, with a high proportion of the U present as U(IV). The sediments were also elevated in reduced S phases and Fe(II), indicating it is very likely that U(VI), Fe(III), and SO4 reduction has occurred or is occurring in the sediment. The microbial community was assessed using lipid- and DNA-based techniques, and statistical redundancy analysis was performed to determine correlations between the microbial community and the geochemistry. Increased concentrations of solid-phase organic C and biomass in the naturally reduced sediment suggests that natural bioreduction is stimulated by a zone of increased organic C concentration associated with fine-grained material and lower permeability to groundwater flow. Characterization of the naturally bioreduced sediment provides an understanding of the natural processes that occur in the sediment under reducing conditions and how they may impact natural attenuation of radionuclides and other redox sensitive materials. Results also suggest the importance of recalcitrant organic C for maintaining reducing conditions and U immobilization.« less

Geochemical, mineralogical and microbiological characteristics of sediment from a naturally reduced zone in a uranium-contaminated aquifer

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

Campbell, Kate M.; Kukkadapu, Ravi K.; Qafoku, Nikolla

2012-05-23

Localized zones or lenses of naturally reduced sediments have the potential to play a significant role in the fate and transport of redox-sensitive metals and metalloids in aquifers. To assess the mineralogy, microbiology, and redox processes that occur in these zones, we examined several cores from a region of naturally occurring reducing conditions in a uranium-contaminated aquifer (Rifle, CO). Sediment samples from a transect of cores ranging from oxic/suboxic Rifle aquifer sediment to naturally reduced sediment were analyzed for uranium and iron content, oxidation state, and mineralogy, reduced sulfur phases, and solid phase organic carbon content using a suite ofmore » analytical and spectroscopic techniques on bulk sediment and size fractions. Solid-phase uranium concentrations were higher in the naturally reduced zone, with a high proportion of the uranium present as reduced U(IV). The sediments were also elevated in reduced sulfur phases and Fe(II), indicating it is very likely that U(VI), Fe(III), and sulfate reduction occurred or is occurring in the sediment. The microbial community was assessed using lipid- and DNA-based techniques, and statistical redundancy analysis was performed to determine correlations between the microbial community and the geochemistry. Increased concentration of solid phase organic carbon and biomass in the naturally reduced sediment suggests that natural bioreduction is stimulated by a zone of increased organic carbon concentration associated with fine-grained material and lower permeability to groundwater flow. Characterization of the naturally bioreduced sediment provides an understanding of the natural processes that occur in the sediment under reducing conditions and how they may impact natural attenuation of radionuclides and other redox sensitive materials. Results also suggest the importance of recalcitrant organic carbon for maintaining reducing conditions and uranium immobilization.« less

Geochemical, mineralogical and microbiological characteristics of sediment from a naturally reduced zone in a uranium-contaminated aquifer

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

Campbell, K. M.; Kukkadapu, R. K.; Qafoku, N. P.

2012-08-01

Localized zones or lenses of naturally reduced sediments have the potential to play a significant role in the fate and transport of redox-sensitive metals and metalloids in aquifers. To assess the mineralogy, microbiology and redox processes that occur in these zones, several cores from a region of naturally occurring reducing conditions in a U-contaminated aquifer (Rifle, CO) were examined. Sediment samples from a transect of cores ranging from oxic/suboxic Rifle aquifer sediment to naturally reduced sediment were analyzed for U and Fe content, oxidation state, and mineralogy; reduced S phases; and solid-phase organic C content using a suite of analyticalmore » and spectroscopic techniques on bulk sediment and size fractions. Solid-phase U concentrations were higher in the naturally reduced zone, with a high proportion of the U present as U(IV). The sediments were also elevated in reduced S phases and Fe(II), indicating it is very likely that U(VI), Fe(III), and SO 4 reduction has occurred or is occurring in the sediment. The microbial community was assessed using lipid- and DNA-based techniques, and statistical redundancy analysis was performed to determine correlations between the microbial community and the geochemistry. Increased concentrations of solid-phase organic C and biomass in the naturally reduced sediment suggests that natural bioreduction is stimulated by a zone of increased organic C concentration associated with fine-grained material and lower permeability to groundwater flow. Characterization of the naturally bioreduced sediment provides an understanding of the natural processes that occur in the sediment under reducing conditions and how they may impact natural attenuation of radionuclides and other redox sensitive materials. Results also suggest the importance of recalcitrant organic C for maintaining reducing conditions and U immobilization.« less

A comparison of Redlich-Kister polynomial and cubic spline representations of the chemical potential in phase field computations

DOE PAGES

Teichert, Gregory H.; Gunda, N. S. Harsha; Rudraraju, Shiva; ...

2016-12-18

Free energies play a central role in many descriptions of equilibrium and non-equilibrium properties of solids. Continuum partial differential equations (PDEs) of atomic transport, phase transformations and mechanics often rely on first and second derivatives of a free energy function. The stability, accuracy and robustness of numerical methods to solve these PDEs are sensitive to the particular functional representations of the free energy. In this communication we investigate the influence of different representations of thermodynamic data on phase field computations of diffusion and two-phase reactions in the solid state. First-principles statistical mechanics methods were used to generate realistic free energymore » data for HCP titanium with interstitially dissolved oxygen. While Redlich-Kister polynomials have formed the mainstay of thermodynamic descriptions of multi-component solids, they require high order terms to fit oscillations in chemical potentials around phase transitions. Here, we demonstrate that high fidelity fits to rapidly fluctuating free energy functions are obtained with spline functions. As a result, spline functions that are many degrees lower than Redlich-Kister polynomials provide equal or superior fits to chemical potential data and, when used in phase field computations, result in solution times approaching an order of magnitude speed up relative to the use of Redlich-Kister polynomials.« less

Combination of sawdust from teak wood and rice husk activated carbon as adsorbent of Pb(II) ion and its analysis using solid-phase spectrophotometry (sps)

NASA Astrophysics Data System (ADS)

Saputro, S.; Mahardiani, L.; Wulandari, D. A.

2018-03-01

This research aimed to know the usage of sawdust of teak wood and rice husk waste as Pb (II) ion adsorbents in simulated liquid waste, the combined optimum mass required adsorbent to adsorb Pb(II) ion, the sensitivity of the solid-phase spectrophotometry (sps) method in determining the decrease of Pb (II) metal ion levels in the μg/L level. This research was conducted by experimental method in laboratory. Adsorbents used in this study were charcoal of sawdust sawdust activated using 15% ZnCl2 solution and activated rice husk using 2 N NaOH solution. The adsorption processes of sawdust and rice husk with Pb(II) solution was done by variation of mass combination with a ratio of 1: 0; 0: 1; 1: 1; 1: 2; and 2: 1. Analysis of Pb(II) ion concentration using SPS and characterization of sawdust and rice husk adsorbent ads using FTIR. The results showed that activated charcoal from sawdust of teak wood and rice husks can be used as Pb (II) metal ion adsorbents with adsorption capacity of 0.86 μg/L, charcoal from sawdust of teak wood and rice husk adsorbent with a combination of optimum mass contact of sawdust and rice husk is 2:1 as much as 3 grams can adsorb 42.80 μg/L. Solid-phase spectophotometry is a sensitive method for analysis of concentration decreasing levels of Pb(II) ion, after it was absorbed by sawdust of teak wood and rice husk with high sensitivity and has the limit of detection (LOD) of 0.06 μg/L.

A novel lab-on-chip platform with integrated solid phase PCR and Supercritical Angle Fluorescence (SAF) microlens array for highly sensitive and multiplexed pathogen detection.

PubMed

Hung, Tran Quang; Chin, Wai Hoe; Sun, Yi; Wolff, Anders; Bang, Dang Duong

2017-04-15

Solid-phase PCR (SP-PCR) has become increasingly popular for molecular diagnosis and there have been a few attempts to incorporate SP-PCR into lab-on-a-chip (LOC) devices. However, their applicability for on-line diagnosis is hindered by the lack of sensitive and portable on-chip optical detection technology. In this paper, we addressed this challenge by combining the SP-PCR with super critical angle fluorescence (SAF) microlens array embedded in a microchip. We fabricated miniaturized SAF microlens array as part of a microfluidic chamber in thermoplastic material and performed multiplexed SP-PCR directly on top of the SAF microlens array. Attribute to the high fluorescence collection efficiency of the SAF microlens array, the SP-PCR assay on the LOC platform demonstrated a high sensitivity of 1.6 copies/µL, comparable to off-chip detection using conventional laser scanner. The combination of SP-PCR and SAF microlens array allows for on-chip highly sensitive and multiplexed pathogen detection with low-cost and compact optical components. The LOC platform would be widely used as a high-throughput biosensor to analyze food, clinical and environmental samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Phase Behavior Modeling of Asphaltene Precipitation for Heavy Crudes: A Promising Tool Along with Experimental Data

NASA Astrophysics Data System (ADS)

Tavakkoli, M.; Kharrat, R.; Masihi, M.; Ghazanfari, M. H.; Fadaei, S.

2012-12-01

Thermodynamic modeling is known as a promising tool for phase behavior modeling of asphaltene precipitation under different conditions such as pressure depletion and CO2 injection. In this work, a thermodynamic approach is used for modeling the phase behavior of asphaltene precipitation. The precipitated asphaltene phase is represented by an improved solid model, while the oil and gas phases are modeled with an equation of state. The PR-EOS was used to perform flash calculations. Then, the onset point and the amount of precipitated asphaltene were predicted. A computer code based on an improved solid model has been developed and used for predicting asphaltene precipitation data for one of Iranian heavy crudes, under pressure depletion and CO2 injection conditions. A significant improvement has been observed in predicting the asphaltene precipitation data under gas injection conditions. Especially for the maximum value of asphaltene precipitation and for the trend of the curve after the peak point, good agreement was observed. For gas injection conditions, comparison of the thermodynamic micellization model and the improved solid model showed that the thermodynamic micellization model cannot predict the maximum of precipitation as well as the improved solid model. The non-isothermal improved solid model has been used for predicting asphaltene precipitation data under pressure depletion conditions. The pressure depletion tests were done at different levels of temperature and pressure, and the parameters of a non-isothermal model were tuned using three onset pressures at three different temperatures for the considered crude. The results showed that the model is highly sensitive to the amount of solid molar volume along with the interaction coefficient parameter between the asphaltene component and light hydrocarbon components. Using a non-isothermal improved solid model, the asphaltene phase envelope was developed. It has been revealed that at high temperatures, an increase in the temperature results in a lower amount of asphaltene precipitation and also it causes the convergence of lower and upper boundaries of the asphaltene phase envelope. This work illustrates successful application of a non-isothermal improved solid model for developing the asphaltene phase envelope of heavy crude which can be helpful for monitoring and controlling of asphaltene precipitation through the wellbore and surface facilities during heavy oil production.

New effects in Langmuir and Langmuir-Blodgett monolayers from fluorescently labelled phospholipids and their possible use for water quality control

NASA Astrophysics Data System (ADS)

Ivanov, G. R.; Geshev, N. I.

2016-02-01

Secondary water contamination poses significant challenges to the sensitivity and selectivity of sensors used for its detection and monitoring. Currently only lab tests can detect these contaminants and by the time this happens the contaminated water has entered the city water supply system. Fluorescent chromophore NitroBenzoxaDiazole (NBD) is very suitable and had been successfully used in biosensor applications due to its high sensitivity to close proximity polarity of the medium. Over the years we have discovered 3 new effects in NBD- labelled phospholipids which can significantly improve the performance of biosensors. The phospholipid matrix provides flexible biocompatible environment for immobilization of selectively reacting enzymes, microorganisms, DNA, immunoagents, whole cells. Use of single layer (3.1 nm thickness) films at the air-water interface (Langmuir films) or deposited on solid support as Langmuir-Blodgett (LB) film gives fast response times for real time monitoring (no slow diffusion processes) and precise molecule ordering and orientation. The first new effect was fluorescence self-quenching in Langmuir and LB films. In the liquid phase films exhibit normal fluorescence. Upon transition to solid phase fluorescence intensity is almost completely self-quenched and fluorescence lifetimes in the nanosecond region decrease 2 times. This is easily measured. Usually large heavy metal atoms quench fluorescence. We observed the opposite new effect when LB film is deposited in the solid phase from a subphase containing heavy metals. The third new effect is the obtaining of nanosized cylinders with bilayer thickness, which remain stable at least for months, when LB monolayer is deposited in the phase coexistence region at thermodynamic equilibrium. This greatly increases reacting surface and sensitivity of possible sensors. Almost all possible optical experimental methods were used for this research. This includes polarized ATR FTIR and polarized UV-VIS spectroscopies, Fluorescence Lifetime Imaging Microscopy (FLIM), Scanning Near-field Optical Microscopy (SNOM).

A quantitative headspace-solid-phase microextraction-gas chromatography-flame ionization detector method to analyze short chain free fatty acids in rat feces.

PubMed

Fiorini, Dennis; Boarelli, Maria Chiara; Gabbianelli, Rosita; Ballini, Roberto; Pacetti, Deborah

2016-09-01

This study sought to develop and validate a quantitative method to analyze short chain free fatty acids (SCFAs) in rat feces by solid-phase microextraction and gas chromatography (SPME-GC) using the salt mixture ammonium sulfate and sodium dihydrogen phosphate as salting out agent. Conditioning and extraction time, linearity, limits of detection and quantification, repeatability, and recovery were evaluated. The proposed method allows quantification with improved sensitivity as compared with other methods exploiting SPME-GC. The method has been applied to analyze rat fecal samples, quantifying acetic, propionic, isobutyric, butyric, isopentanoic, pentanoic, and hexanoic acids. Copyright © 2016 Elsevier Inc. All rights reserved.

Charged derivatization and on-line solid phase extraction to measure extremely low cortisol and cortisone levels in human saliva with liquid chromatography-tandem mass spectrometry.

PubMed

Magda, Balázs; Dobi, Zoltán; Mészáros, Katalin; Szabó, Éva; Márta, Zoltán; Imre, Tímea; Szabó, Pál T

2017-06-05

The aim of this study was to develop a sensitive, reliable and high-throughput liquid chromatography - electrospray ionization - mass spectrometric (LC-ESI-MS/MS) method for the simultaneous quantitation of cortisol and cortisone in human saliva. Derivatization with 2-hydrazino-1-methylpyridine (HMP) was one of the most challenging aspects of the method development. The reagent was reacting with cortisol and cortisone at 60°C within 1h, giving mono- and bis-hydrazone derivatives. Investigation of derivatization reaction and sample preparation was detailed and discussed. Improvement of method sensitivity was achieved with charged derivatization and use of on-line solid phase extraction (on-line SPE). The lower limit of quantitation (LLOQ) was 5 and 10pg/ml for cortisol and cortisone, respectively. The developed method was subsequently applied to clinical laboratory measurement of cortisol and cortisone in human saliva. Copyright © 2017 Elsevier B.V. All rights reserved.

Adjusted active carbon fibers for solid phase microextraction.

PubMed

Jia, Jinping; Feng, Xue; Fang, Nenghu; Wang, Yalin; Chen, Hongjin; Dan, Wu

2002-01-01

Adjusted active carbon fiber (AACF) was evaluated for Solid Phase Microextraction (SPME), which showed higher sensitivity and stability than traditional coating fibers. The characteristics of AACF result from two different activation methods (chemical and water vapor) and from variable activation conditions (temperature and time). The fiber treated by water vapor appears to have stronger affinity to polar compounds, while that treated by chemical activation appears to have stronger affinity to non-polar compounds. For different target compounds ranged from non-polar to polar, AACF design could be effective with specific selections and sensitivities. As applications in this paper, benzoic acid in soy sauce was extracted onto water-vapor-activated-fiber, then analyzed using gas chromatograph-mass spectrometer (GC-MS). The chemical-activated-fiber SPME was applied in the analysis of benzene series compounds (BTEX) in water matrix. Compared with standard carbon disulfide extraction method, chemical-activated-fiber SPME is more convenient due to its simple process and turns to be of relative low detection limits.

Sol-gel titania-coated needles for solid phase dynamic extraction-GC/MS analysis of desomorphine and desocodeine.

PubMed

Su, Chi-Ju; Srimurugan, Sankarewaran; Chen, Chinpiao; Shu, Hun-Chi

2011-01-01

Novel sol-gel titania film coated needles for solid-phase dynamic extraction (SPDE)-GC/MS analysis of desomorphine and desocodeine are described. The high thermal stability of titania film permits efficient extraction and analysis of poorly volatile opiate drugs. The influences of sol-gel reaction time, coating layer, extraction and desorption time and temperature on the SPDE needle performance were investigated. The deuterium labeled internal standard was introduced either during the extraction of analyte or directly injected to GC after the extraction process. The latter method was shown to be more sensitive for the analysis of water and urine samples containing opiate drugs. The proposed conditions provided a wide linear range (from 5-5000 ppb), and satisfactory linearity, with R(2) values from 0.9958 to 0.9999, and prominent sensitivity, LOQs (1.0-5.0 ng/g). The sol-gel titania film coated needle with SPDE-GC/MS will be a promising technique for desomorphine and desocodeine analysis in urine.

Constant frequency pulsed phase-locked-loop instrument for measurement of ultrasonic velocity

NASA Technical Reports Server (NTRS)

Yost, William T.; Cantrell, John H.; Kushnick, Peter W.

1991-01-01

A new instrument based on a constant-frequency pulsed phase-locked-loop (CFPPLL) concept has been developed to accurately measure the ultrasonic wave velocity in liquids and changes in ultrasonic wave velocity in solids and liquids. An analysis of the system shows that it is immune to many of the frequency-dependent effects that plague other techniques. Measurements of the sound velocity in ultrapure water are used to confirm the analysis. The results are in excellent agreement with values from the literature, and establish that the CFPPLL provides a reliable, accurate way to measure velocities, as well as for monitoring small changes in velocity without the sensitivity to frequency-dependent phase shifts common to other measurement systems. The estimated sensitivity to phase changes is better than a few parts in 10 to the 7th.

Microscale reconstruction of biogeochemical substrates using multimode X-ray tomography and scanning electron microscopy

NASA Astrophysics Data System (ADS)

Miller, M.; Miller, E.; Liu, J.; Lund, R. M.; McKinley, J. P.

2012-12-01

X-ray computed tomography (CT), scanning electron microscopy (SEM), electron microprobe analysis (EMP), and computational image analysis are mature technologies used in many disciplines. Cross-discipline combination of these imaging and image-analysis technologies is the focus of this research, which uses laboratory and light-source resources in an iterative approach. The objective is to produce images across length scales, taking advantage of instrumentation that is optimized for each scale, and to unify them into a single compositional reconstruction. Initially, CT images will be collected using both x-ray absorption and differential phase contrast modes. The imaged sample will then be physically sectioned and the exposed surfaces imaged and characterized via SEM/EMP. The voxel slice corresponding to the physical sample surface will be isolated computationally, and the volumetric data will be combined with two-dimensional SEM images along CT image planes. This registration step will take advantage of the similarity between the X-ray absorption (CT) and backscattered electron (SEM) coefficients (both proportional to average atomic number in the interrogated volume) as well as the images' mutual information. Elemental and solid-phase distributions on the exposed surfaces, co-registered with SEM images, will be mapped using EMP. The solid-phase distribution will be propagated into three-dimensional space using computational methods relying on the estimation of compositional distributions derived from the CT data. If necessary, solid-phase and pore-space boundaries will be resolved using X-ray differential phase contrast tomography, x-ray fluorescence tomography, and absorption-edge microtomography at a light-source facility. Computational methods will be developed to register and model images collected over varying scales and data types. Image resolution, physically and dynamically, is qualitatively different for the electron microscopy and CT methodologies. Routine CT images are resolved at 10-20 μm, while SEM images are resolved at 10-20 nm; grayscale values vary according to collection time and instrument sensitivity; and compositional sensitivities via EMP vary in interrogation volume and scale. We have so far successfully registered SEM imagery within a multimode tomographic volume and have used standard methods to isolate pore space within the volume. We are developing a three-dimensional solid-phase identification and registration method that is constrained by bulk-sample X-ray diffraction Rietveld refinements. The results of this project will prove useful in fields that require the fine-scale definition of solid-phase distributions and relationships, and could replace more inefficient methods for making these estimations.

The effect of solute additions on the steady-state creep behavior of dispersion-strengthened aluminum.

NASA Technical Reports Server (NTRS)

Reynolds, G. H.; Lenel, F. V.; Ansell, G. S.

1971-01-01

The effect of solute additions on the steady-state creep behavior of coarse-grained dispersion-strengthened aluminum alloys was studied. Recrystallized dispersion-strengthened solid solutions were found to have stress and temperature sensitivities quite unlike those observed in single-phase solid solutions having the same composition and grain size. The addition of magnesium or copper to the matrix of a recrystallized dispersion-strengthened aluminum causes a decrease in the steady-state creep rate which is much smaller than that caused by similar amounts of solute in single-phase solid solutions. All alloys exhibited essentially a 4.0 power stress exponent in agreement with the model of Ansell and Weertman. The activation energy for steady-state creep in dispersion-strengthened Al-Mg alloys, as well as the stress dependence, was in agreement with the physical model of dislocation climb over the dispersed particles.

Rapid detection of HSO4- in water: Novel immobilized azo-azomethine colorimetric anion receptors on solid supports

NASA Astrophysics Data System (ADS)

Hezaveh, Saba Mahdavi; Khanmohammadi, Hamid; Zendehdel, Mojgan

2018-06-01

The immobilized azo-azomethine receptors on amorphous SiO2, S-B, SiO2 nanoparticles, S-NPs, and NaY zeolite, S-ZY, have been prepared and applied as solid phase sensors for detection of HSO4-, over other interfering anions, in 100% aqueous media. Remarkably, S-B and S-ZY show unique and rapid sensitivity towards HSO4-, which could it easily visualized through naked eye detection even at 5 × 10-4 mol L-1 and 4 × 10-4 mol L-1, respectively. The fabricated solid phase sensors were characterized using powder XRD diffraction, TGA-DTA, FE-SEM and also FT-IR techniques. Moreover, the related molecular anion receptor, HL, has been prepared and used for naked eye detection of F- and AcO-, in dry DMSO. The anions recognition ability of HL was also evaluated using UV-Vis and 1H NMR spectroscopic methods.

Multiresidue determination of 114 multiclass pesticides in flue-cured tobacco by solid-phase extraction coupled with gas chromatography and tandem mass spectrometry.

PubMed

Cao, Jianmin; Sun, Na; Yu, Weisong; Pang, Xueli; Lin, Yingnan; Kong, Fanyu; Qiu, Jun

2016-12-01

A sensitive and robust multiresidue method for the simultaneous analysis of 114 pesticides in tobacco was developed based on solid-phase extraction coupled with gas chromatography and tandem mass spectrometry. In this strategy, tobacco samples were extracted with acetonitrile and cleaned up with a multilayer solid-phase extraction cartridge Cleanert TPT using acetonitrile/toluene (3:1) as the elution solvent. Two internal standards of different polarity were used to meet simultaneous pesticides quantification demands in the tobacco matrix. Satisfactory linearity in the range of 10-500 ng/mL was obtained for all 114 pesticides with linear regression coefficients higher than 0.994. The limit of detection and limit of quantification values were 0.02-5.27 and 0.06-17.6 ng/g, respectively. For most of the pesticides, acceptable recoveries in the range of 70-120% and repeatabilities (relative standard deviation) of <11% were achieved at spiking levels of 20, 100, and 400 ng/g. Compared with the reported multiresidue analytical method, the proposed method provided a cleaner test solution with smaller amounts of pigments, fatty acids as well as other undesirable interferences. The development and validation of the high sensitivity, high selectivity, easy automation, and high-throughput analytical method meant that it could be successfully used for the determination of pesticides in tobacco samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Facts and Fallacies of Kidd Antibodies: Experience in a Tertiary Care Hospital in North India.

PubMed

Makroo, R N; Nayak, Sweta; Chowdhry, Mohit; Karna, Prashant

2017-06-01

We have analyzed the method used in our laboratory to detect the most elusive, clinically significant alloantibody: the Kidd alloantibodies and find the most convenient procedure. A retrospective analysis of the method used in our laboratory for determining Kidd alloantibodies from January 2013 to May 2015 was conducted. The details of the event that sensitized the patient for red cell antibody formation and procedure used to detect the alloantibody were retrieved from the departmental records. Of 405 red cell antibody identification cases, 24 (5.9 %) had Kidd antibody (anti-Jka in 12: 50 % cases; anti-Jkb in 4: 16.7 % cases; multiple antibodies in 8: 32 % cases). Thirteen of 24 patients (54.2 %) had autocontrol positive of which 6 cases needed adsorption procedures whereas antibody/ies could be identified without adsorption procedure in the remaining 7 cases. All the 7 cases had autocontrol of 1+ strength. Of the 11 patients (45.8 %) with autocontrol negative, the antibody was identified using solid phase in 7 cases whereas tube panels were also used in the remaining 4 cases. Kidd alloantibodies though deceptive can be identified by sensitive techniques like the solid phase and simple but laborious techniques using the tube cell panels. Depending upon the reaction strength of the autocontrol, the routine autoadsorption process may be skipped and tube cell enzyme treated cells or solid phase techniques be used to get the results.

Magnetic covalent triazine-based frameworks as magnetic solid-phase extraction adsorbents for sensitive determination of perfluorinated compounds in environmental water samples.

PubMed

Ren, Ji-Yun; Wang, Xiao-Li; Li, Xiao-Li; Wang, Ming-Lin; Zhao, Ru-Song; Lin, Jin-Ming

2018-02-01

Covalent organic frameworks (COFs), which are a new type of carbonaceous polymeric material, have attracted great interest because of their large surface area and high chemical and thermal stability. However, to the best of our knowledge, no work has reported the use of magnetic COFs as adsorbents for magnetic solid-phase extraction (MSPE) to enrich and determine environmental pollutants. This work aims to investigate the feasibility of using covalent triazine-based framework (CTF)/Fe 2 O 3 composites as MSPE adsorbents to enrich and analyze perfluorinated compounds (PFCs) at trace levels in water samples. Under the optimal conditions, the method developed exhibited low limits of detection (0.62-1.39 ng·L -1 ), a wide linear range (5-4000 ng L -1 ), good repeatability (1.12-9.71%), and good reproducibility (2.45-7.74%). The new method was successfully used to determine PFCs in actual environmental water samples. MSPE based on CTF/Fe 2 O 3 composites exhibits potential for analysis of PFCs at trace levels in environmental water samples. Graphical abstract Magnetic covalent triazine-based frameworks (CTFs) were used as magnetic solid-phase extraction adsorbents for the sensitive determination of perfluorinated compounds in environmental water samples. PFBA perfluorobutyric acid, PFBS perfluorobutane sulfonate, PFDA perfluorodecanoic acid, PFDoA perfluorododecanoic acid, PFHpA perfluoroheptanoic acid, PFHxA perfluorohexanoic acid, PFHxS perfluorohexane sulfonate, PFNA perfluorononanoic acid, PFOA perfluorooctanoic acid, PFPeA perfluoropentanoic acid, PFUdA Perfluoroundecanoic acid.

A new approach for downscaling of electromembrane extraction as a lab on-a-chip device followed by sensitive Red-Green-Blue detection.

PubMed

Baharfar, Mahroo; Yamini, Yadollah; Seidi, Shahram; Arain, Muhammad Balal

2018-05-30

A new design of electromembrane extraction (EME) as a lab on-a-chip device was proposed for the extraction and determination of phenazopyridine as the model analyte. The extraction procedure was accomplished by coupling of EME and the packing of a sorbent. The analyte was extracted under the applied electrical field across a membrane sheet impregnated by nitrophenyl octylether (NPOE) into an acceptor phase. It was followed by the absorption of the analyte on strong cation exchanger as a sorbent. The designed chip contained separate spiral channels for donor and acceptor phases featuring embedded platinum electrodes to enhance extraction efficiency. The selected donor and acceptor phases were 0 mM HCl and 100 mM HCl, respectively. The on-chip electromembrane extraction was carried out under the voltage level of 70 V for 50 min. The analysis was carried out by two modes of a simple Red-Green-Blue (RGB) image analysis tool and a conventional HPLC-UV system. After the absorption of the analyte on the solid phase, its color changed and a digital picture of the sorbent was taken for the RGB analysis. The effective parameters on the performance of the chip device, comprising the EME and solid phase microextraction steps, were distinguished and optimized. The accumulation of the analyte on the solid phase showed excellent sensitivity and a limit of detection (LOD) lower than 1.0 μg L-1 achieved by an image analysis using a smartphone. This device also offered acceptable intra- and inter-assay RSD% (<10%). The calibration curves were linear within the range of 10-1000 μg L-1 and 30-1000 μg L-1 (r2 > 0.9969) for HPLC-UV and RGB analysis, respectively. To investigate the applicability of the method in complicated matrices, urine samples of patients being treated with phenazopyridine were analyzed.

Sensitive method for the quantitative determination of bromocriptine in human plasma by liquid chromatography-tandem mass spectrometry.

PubMed

Salvador, Arnaud; Dubreuil, Didier; Denouel, Jannick; Millerioux, L

2005-06-25

A sensitive LC-MS-MS assay for the quantitative determination of bromocriptine has been developed and validated and is described in this work. The assay involved the extraction of the analyte from 1 ml of human plasma using a solid phase extraction on Oasis MCX cartridges. Chromatography was performed on a Symmetry C18 (2.1 mm x 100 mm, 3.5 microm) column using a mobile phase consisting of 25:75:01 acetonitrile-water-formic acid with a flow rate of 250 microl/min. The linearity was within the concentration range of 2-500 pg/ml. The lower limit of quantification was 2 pg/ml. This method has been demonstrated to be an improvement over existing methods due to its greater sensitivity and specificity.

New Dioxaborolane Chemistry Enables [18F]-Positron-Emitting, Fluorescent [18F]-Multimodality Biomolecule Generation from the Solid Phase

PubMed Central

Crisp, Jessica L.; Vera, David R.; Tsien, Roger Y.; Ting, Richard

2016-01-01

New protecting group chemistry is used to greatly simplify imaging probe production. Temperature and organic solvent-sensitive biomolecules are covalently attached to a biotin-bearing dioxaborolane, which facilitates antibody immobilization on a streptavidin-agarose solid-phase support. Treatment with aqueous fluoride triggers fluoride-labeled antibody release from the solid phase, separated from unlabeled antibody, and creates [18F]-trifluoroborate-antibody for positron emission tomography and near-infrared fluorescent (PET/NIRF) multimodality imaging. This dioxaborolane-fluoride reaction is bioorthogonal, does not inhibit antigen binding, and increases [18F]-specific activity relative to solution-based radiosyntheses. Two applications are investigated: an anti-epithelial cell adhesion molecule (EpCAM) monoclonal antibody (mAb) that labels prostate tumors and Cetuximab, an anti-epidermal growth factor receptor (EGFR) mAb (FDA approved) that labels lung adenocarcinoma tumors. Colocalized, tumor-specific NIRF and PET imaging confirm utility of the new technology. The described chemistry should allow labeling of many commercial systems, diabodies, nanoparticles, and small molecules for dual modality imaging of many diseases. PMID:27064381

New Dioxaborolane Chemistry Enables [(18)F]-Positron-Emitting, Fluorescent [(18)F]-Multimodality Biomolecule Generation from the Solid Phase.

PubMed

Rodriguez, Erik A; Wang, Ye; Crisp, Jessica L; Vera, David R; Tsien, Roger Y; Ting, Richard

2016-05-18

New protecting group chemistry is used to greatly simplify imaging probe production. Temperature and organic solvent-sensitive biomolecules are covalently attached to a biotin-bearing dioxaborolane, which facilitates antibody immobilization on a streptavidin-agarose solid-phase support. Treatment with aqueous fluoride triggers fluoride-labeled antibody release from the solid phase, separated from unlabeled antibody, and creates [(18)F]-trifluoroborate-antibody for positron emission tomography and near-infrared fluorescent (PET/NIRF) multimodality imaging. This dioxaborolane-fluoride reaction is bioorthogonal, does not inhibit antigen binding, and increases [(18)F]-specific activity relative to solution-based radiosyntheses. Two applications are investigated: an anti-epithelial cell adhesion molecule (EpCAM) monoclonal antibody (mAb) that labels prostate tumors and Cetuximab, an anti-epidermal growth factor receptor (EGFR) mAb (FDA approved) that labels lung adenocarcinoma tumors. Colocalized, tumor-specific NIRF and PET imaging confirm utility of the new technology. The described chemistry should allow labeling of many commercial systems, diabodies, nanoparticles, and small molecules for dual modality imaging of many diseases.

Simple fabrication of solid phase microextraction fiber employing nitrogen-doped ordered mesoporous polymer by in situ polymerization.

PubMed

Zheng, Juan; Liang, Yeru; Liu, Shuqin; Jiang, Ruifen; Zhu, Fang; Wu, Dingcai; Ouyang, Gangfeng

2016-01-04

A combination of nitrogen-doped ordered mesoporous polymer (NOMP) and stainless steel wires led to highly sensitive, selective, and stable solid phase microextraction (SPME) fibers by in situ polymerization for the first time. The ordered structure of synthesized NOMP coating was illustrated by transmission electron microscopy (TEM) and X-ray diffraction (XRD), and microscopy analysis by scanning electron microscopy (SEM) confirmed a homogenous morphology of the NOMP-coated fiber. The NOMP-coated fiber was further applied for the extraction of organochlorine pesticides (OCPs) with direct-immersion solid-phase microextraction (DI-SPME) method followed by gas chromatography-mass spectrometry (GC-MS) quantification. Under the optimized conditions, low detection limits (0.023-0.77 ng L(-1)), a wide linear range (9-1500 ng L(-1)), good repeatability (3.5-8.1%, n=6) and excellent reproducibility (1.5-8.3%, n=3) were achieved. Moreover, the practical feasibility of the proposed method was evaluated by determining OCPs in environmental water samples with satisfactory recoveries. Copyright © 2015 Elsevier B.V. All rights reserved.

Molecularly imprinted solid-phase extraction for the determination of ten macrolide drugs residues in animal muscles by liquid chromatography-tandem mass spectrometry.

PubMed

Song, Xuqin; Zhou, Tong; Liu, Qingying; Zhang, Meiyu; Meng, Chenying; Li, Jiufeng; He, Limin

2016-10-01

A simple and sensitive method based on molecularly imprinted solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry was developed for the determination of the residues of ten macrolide drugs in swine, cattle and chicken muscles samples. The molecularly imprinted polymers (MIPs) were synthesized using tylosin as a template and methacrylic acid as a functional monomer. Samples were extracted with sodium borate buffer solution and ethyl acetate, and purified by the MIP cartridge. The results showed that the cartridge exhibited good recognition performance for macrolides, and better purification effect than the traditional solid-phase extraction cartridges. Recoveries of analytes at three spiking levels 1, 5 and 20μgkg(-1) ranged from 60.7% to 100.3% with the relative standard deviations less than 14%. The limits of detection of the method were between 0.1 and 0.4μgkg(-1). The method is useful for the routine monitoring of the residues of macrolide drugs in animal muscles. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Effect of organic and inorganic toxic compounds on luminescence of luminous fungi].

PubMed

Vydriakova, G A; Gusev, A A; Medvedeva, S E

2011-01-01

The possibility of the development of the solid phase bioluminescent biotest using aerial mycelium of the luminous fungi was investigated. Effect of organic and inorganic toxic compounds (TC) at concentrations from 10(-6) to 1 mg/ml on luminescence of aerial mycelia of four species of luminous fungi-Armillaria borealis (Culture Collection of the Institute of Forest, Siberian Branch, Russian Academy of Sciences), A. mellea, A. gallica, and Lampteromyces japonicus (Fungi Collection of the Botanical Institute, Russian Academy of Sciences)--has been studied. Culture of A. mellea was shown to be most sensitive to solutions of the model TC. It was demonstrated that the sensitivity of the luminous fungi is comparable with the sensitivity of the bacteria that are used for environmental monitoring. Use of the aerial mycelium of the luminous fungi on the solid support as a test object is a promising approach in biotesting for the development of continuous biosensors for air monitoring.

[Simultaneous determination of nine estrogens in eel by ultrafast liquid chromatography-tandem mass spectrometry with isotope dilution technique and solid-phase extraction].

PubMed

Chen, Xiaohong; Yao, Shanshan; Li, Xiaoping; Zhao, Yonggang; Jin, Micong

2012-11-01

Developing a rapid and sensitive analytical method based on ultrafast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) with solid-phase extraction (SPE) for the simultaneous determination of nine estrogens (dienestrol, diethylstilbestrol, estrone, hexestrol, 17-alpha-estradiol, 17-beta-estradiol, estriol, 17alpha-ethinylestradiol and estradiol valerate) in eel. After the sample was extracted by acetonitrile and cleaned by Waters Oasis HLB solid-phase extraction cartridge, the UFLC separation was performed on a Shim-pack XR-ODS II column (100 mm x 2.0 mm, 2.2 microm) with a linear gradient elution program of methanol solution containing 0.04% ammonia (v/v) and 0.04% ammonia aqueous solution (v/v) as the mobile phase. Electrospray ionization was applied and operated in the negative multiple reaction monitoring (MRM) mode. The quantitation was used by isotope internal standard dilution technique. The results showed that the limits of quantitation (LOQs, S/N(10) were in the range of 0.07-0.4 microg/kg, the calibration curves were in good linearities for the nine analytes in the range of 0.5-50.0 microg/L with the correlative coefficients (r2) more than 0.998, the recoveries were between 81.0% and 110.0% with the relative standard deviations (RSDs) of 1.92%-8.24%. Additional, the mass spectra characterization of the nine estrogens was discussed and the fragmentation pathways were speculated. The developed method is rapid, sensitive, specific and reproducible, and adapts not only to the simultaneous determination of the nine trace estrogens including the epimer of 17-alpha-estradiol and 17-beta-estradiol but also to the identified detection in other fish tissues.

Optimization and application of parallel solid-phase extraction coupled with ultra-high performance liquid chromatography-tandem mass spectrometry for the determination of 11 aminoglycoside residues in honey and royal jelly.

PubMed

Wang, Xinran; Yang, Shupeng; Li, Yi; Zhang, Jinzhen; Jin, Yue; Zhao, Wen; Zhang, Yongxin; Huang, Jingping; Wang, Peng; Wu, Cuiling; Zhou, Jinhui

2018-03-23

A robust and sensitive method of solid-phase extraction followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was established and performed for the simultaneous determination of eleven aminoglycosides (AGs) in royal jelly and honey. After sample extraction by a phosphate buffer containing trichloroacetic acid (TCA) and ethylenediaminetetracetic acid disodium salt (Na 2 EDTA), the extraction solution was subjected to a parallel solid-phase extraction for clean-up prior to the LC-MS/MS analysis. The same method was applied to analyze two completely different matrices, honey and royal jelly. Good sensitivity, repeatability, and recovery were obtained by using the mobile phase without an ion-pairing reagent such as heptafluorobutyric acid (HFBA) or sodium heptanesulfonate. The calibration curves of the honey and royal jelly samples exhibited a good linear response (R 2  > 0.99) at six concentrations in the range of 10-1000 μg/mL. The limit of quantification (LOQ) of the AGs ranged from 10 to 25 μg/kg in the honey and from 12.5 to 25 μg/kg in the royal jelly. The recoveries of the AGs for the honey and royal jelly samples were in the range of 79.48% to 108.95% and 74.61% to 113.70% respectively and the relative standard deviations (RSDs) were between 1.23% and 9.59%, and between 1.51% and 9.98%, respectively. The proposed approach has been allowed in China as a reference method for the simultaneous determination of eleven AGs in honey and royal jelly. Copyright © 2018 Elsevier B.V. All rights reserved.

Determination of quaternary ammonium compounds in seawater samples by solid-phase extraction and liquid chromatography-mass spectrometry.

PubMed

Bassarab, P; Williams, D; Dean, J R; Ludkin, E; Perry, J J

2011-02-04

A method for the simultaneous determination of two biocidal quaternary ammonium compounds; didecyldimethylammonium chloride (didecyldimethyl quat) and dodecylbenzyldimethylammonium chloride (benzyl quat), in seawater by solid phase extraction (SPE) followed by liquid chromatography-mass spectrometry (LC-MS) was developed. The optimised procedure utilised off-line extraction of the analytes from seawater using polymeric (Strata-X) SPE cartridges. Recoveries ranged from 80 to 105%, with detection limits at the low parts-per-trillion (ng/l) level for both analytes. To demonstrate sensitivity, environmental concentrations were measured at three different locations along the North East coast of England with measured values in the range 120-270ng/l. Copyright © 2010 Elsevier B.V. All rights reserved.

Analysis of Volatile Fragrance and Flavor Compounds by Headspace Solid Phase Microextraction and GC-MS: An Undergraduate Instrumental Analysis Experiment

NASA Astrophysics Data System (ADS)

Galipo, Randolph C.; Canhoto, Alfredo J.; Walla, Michael D.; Morgan, Stephen L.

1999-02-01

A senior-level undergraduate laboratory experiment that demonstrates the use of solid-phase microextraction (SPME) and capillary gas chromatography-mass spectrometry (GC-MS) was developed for the identification of volatile compounds in consumer products. SPME minimizes sample preparation and concentrates volatile analytes in a solvent-free manner. Volatile flavor and fragrance compounds were extracted by SPME from the headspace of vials containing shampoos, chewing gums, and perfumes and analyzed by GC-MS. Headspace SPME was shown to be more sensitive than conventional headspace analysis of similar samples performed with an airtight syringe. Analysis times were less than 30 min, allowing multiple analyses to be performed in a typical laboratory class period.

Super-sensitive time-resolved fluoroimmunoassay for thyroid-stimulating hormone utilizing europium(III) nanoparticle labels achieved by protein corona stabilization, short binding time, and serum preprocessing.

PubMed

Näreoja, Tuomas; Rosenholm, Jessica M; Lamminmäki, Urpo; Hänninen, Pekka E

2017-05-01

Thyrotropin or thyroid-stimulating hormone (TSH) is used as a marker for thyroid function. More precise and more sensitive immunoassays are needed to facilitate continuous monitoring of thyroid dysfunctions and to assess the efficacy of the selected therapy and dosage of medication. Moreover, most thyroid diseases are autoimmune diseases making TSH assays very prone to immunoassay interferences due to autoantibodies in the sample matrix. We have developed a super-sensitive TSH immunoassay utilizing nanoparticle labels with a detection limit of 60 nU L -1 in preprocessed serum samples by reducing nonspecific binding. The developed preprocessing step by affinity purification removed interfering compounds and improved the recovery of spiked TSH from serum. The sensitivity enhancement was achieved by stabilization of the protein corona of the nanoparticle bioconjugates and a spot-coated configuration of the active solid-phase that reduced sedimentation of the nanoparticle bioconjugates and their contact time with antibody-coated solid phase, thus making use of the higher association rate of specific binding due to high avidity nanoparticle bioconjugates. Graphical Abstract We were able to decrease the lowest limit of detection and increase sensitivity of TSH immunoassay using Eu(III)-nanoparticles. The improvement was achieved by decreasing binding time of nanoparticle bioconjugates by small capture area and fast circular rotation. Also, we applied a step to stabilize protein corona of the nanoparticles and a serum-preprocessing step with a structurally related antibody.

Ultra-sensitive speciation analysis of mercury by CE-ICP-MS together with field-amplified sample stacking injection and dispersive solid-phase extraction.

PubMed

Chen, YiQuan; Cheng, Xian; Mo, Fan; Huang, LiMei; Wu, Zujian; Wu, Yongning; Xu, LiangJun; Fu, FengFu

2016-04-01

A simple dispersive solid-phase extraction (DSPE) used to extract and preconcentrate ultra-trace MeHg, EtHg and Hg(2+) from water sample, and a sensitive method for the simultaneous analysis of MeHg, EtHg and Hg(2+) by using capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS) with field-amplified sample stacking injection (FASI) were first reported in this study. The DSPE used thiol cotton particles as adsorbent, and is simple and effective. It can be used to extract and preconcentrate ultra-trace mercury compounds in water samples within 30 min with a satisfied recovery and no mercury species alteration during the process. The FASI enhanced the sensitivity of CE-ICP-MS with 25-fold, 29-fold and 27-fold for MeHg, EtHg and Hg(2+) , respectively. Using FASI-CE-ICP-MS together with DSPE, we have successfully determined ultra-trace MeHg, EtHg and Hg(2+) in tap water with a limits of quantification (LOQs) of 0.26-0.45 pg/mL, an RSD (n = 3) < 6% and a recovery of 92-108%. Ultra-high sensitivity, as well as much less sample and reagent consumption and low operating cost, make our method a valuable technique to the speciation analysis of ultra-trace mercury. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel hybrid metal-organic framework-polymeric monolith for solid-phase microextraction.

PubMed

Lin, Chen-Lan; Lirio, Stephen; Chen, Ya-Ting; Lin, Chia-Her; Huang, Hsi-Ya

2014-03-17

This study describes the fabrication of a novel hybrid metal-organic framework- organic polymer (MOF-polymer) for use as a stationary phase in fritless solid-phase microextraction (SPME) for validating analytical methods. The MOF-polymer was prepared by using ethylene dimethacrylate (EDMA), butyl methacrylate (BMA), and an imidazolium-based ionic liquid as porogenic solvent followed by microwave-assisted polymerization with the addition of 25 % MOF. This novel hybrid MOF-polymer was used to extract penicillin (penicillin G, penicillin V, oxacillin, cloxacillin, nafcillin, dicloxacillin) under different conditions. Quantitative analysis of the extracted penicillin samples using the MOF-organic polymer for SPME was conducted by using capillary electrochromatography (CEC) coupled with UV analysis. The penicillin recovery was 63-96.2 % with high reproducibility, sensitivity, and reusability. The extraction time with the proposed fabricated SPME was only 34 min. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simultaneous determination of all-trans and 13-cis retinoic acids and their 4-oxo metabolites by adsorption liquid chromatography after solid-phase extraction.

PubMed

Lefebvre, P; Agadir, A; Cornic, M; Gourmel, B; Hue, B; Dreux, C; Degos, L; Chomienne, C

1995-04-07

All-trans retinoic acid (all-trans RA), the active metabolite of vitamin A, has been demonstrated to be an efficient alternative to chemotherapy in the treatment of acute promyelocytic leukemia (APL), the AML3 subtype of the FAB cytological classification. Complete remission is obtained by inducing terminal granulocytic differentiation of the leukemic cells. To study all-trans RA pharmacokinetics in patients with APL, a rapid, precise and selective high-performance liquid chromatographic (HPLC) assay was developed. This method is easy and shows good repeatability (C.V. = 8.41-12.44%), reproducibility (C.V. = 9.19-14.73%), accuracy (C.V. = 3.5-11%) and sensitivity with a detection limit of 5 pmol/ml. The analysis is performed using normal-phase HPLC in an isocratic mode with UV detection after solid-phase extraction on octadecyl (C18) columns. The mobile phase is hexane-dichloromethane-dioxane (78:18:4, v/v) containing 1% acetic acid.

Solid-phase proximity ligation assays for individual or parallel protein analyses with readout via real-time PCR or sequencing.

PubMed

Nong, Rachel Yuan; Wu, Di; Yan, Junhong; Hammond, Maria; Gu, Gucci Jijuan; Kamali-Moghaddam, Masood; Landegren, Ulf; Darmanis, Spyros

2013-06-01

Solid-phase proximity ligation assays share properties with the classical sandwich immunoassays for protein detection. The proteins captured via antibodies on solid supports are, however, detected not by single antibodies with detectable functions, but by pairs of antibodies with attached DNA strands. Upon recognition by these sets of three antibodies, pairs of DNA strands brought in proximity are joined by ligation. The ligated reporter DNA strands are then detected via methods such as real-time PCR or next-generation sequencing (NGS). We describe how to construct assays that can offer improved detection specificity by virtue of recognition by three antibodies, as well as enhanced sensitivity owing to reduced background and amplified detection. Finally, we also illustrate how the assays can be applied for parallel detection of proteins, taking advantage of the oligonucleotide ligation step to avoid background problems that might arise with multiplexing. The protocol for the singleplex solid-phase proximity ligation assay takes ~5 h. The multiplex version of the assay takes 7-8 h depending on whether quantitative PCR (qPCR) or sequencing is used as the readout. The time for the sequencing-based protocol includes the library preparation but not the actual sequencing, as times may vary based on the choice of sequencing platform.

Persistent dopants and phase segregation in organolead mixed-halide perovskites

DOE PAGES

Rosales, Bryan A.; Men, Long; Cady, Sarah D.; ...

2016-07-25

Organolead mixed-halide perovskites such as CH 3NH 3PbX 3–aX' a (X, X' = I, Br, Cl) are interesting semiconductors because of their low cost, high photovoltaic power conversion efficiencies, enhanced moisture stability, and band gap tunability. Using a combination of optical absorption spectroscopy, powder X-ray diffraction (XRD), and, for the first time, 207Pb solid state nuclear magnetic resonance (ssNMR), we probe the extent of alloying and phase segregation in these materials. Because 207Pb ssNMR chemical shifts are highly sensitive to local coordination and electronic structure, and vary linearly with halogen electronegativity and band gap, this technique can provide the truemore » chemical speciation and composition of organolead mixed-halide perovskites. We specifically investigate samples made by three different preparative methods: solution phase synthesis, thermal annealing, and solid phase synthesis. 207Pb ssNMR reveals that nonstoichiometric dopants and semicrystalline phases are prevalent in samples made by solution phase synthesis. We show that these nanodomains are persistent after thermal annealing up to 200 °C. Further, a novel solid phase synthesis that starts from the parent, single-halide perovskites can suppress phase segregation but not the formation of dopants. Our observations are consistent with the presence of miscibility gaps and spontaneous spinodal decomposition of the mixed-halide perovskites at room temperature. This underscores how strongly different synthetic procedures impact the nanostructuring and composition of organolead halide perovskites. In conclusion, better optoelectronic properties and improved device stability and performance may be achieved through careful manipulation of the different phases and nanodomains present in these materials.« less

Persistent dopants and phase segregation in organolead mixed-halide perovskites

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

Rosales, Bryan A.; Men, Long; Cady, Sarah D.

Organolead mixed-halide perovskites such as CH 3NH 3PbX 3–aX' a (X, X' = I, Br, Cl) are interesting semiconductors because of their low cost, high photovoltaic power conversion efficiencies, enhanced moisture stability, and band gap tunability. Using a combination of optical absorption spectroscopy, powder X-ray diffraction (XRD), and, for the first time, 207Pb solid state nuclear magnetic resonance (ssNMR), we probe the extent of alloying and phase segregation in these materials. Because 207Pb ssNMR chemical shifts are highly sensitive to local coordination and electronic structure, and vary linearly with halogen electronegativity and band gap, this technique can provide the truemore » chemical speciation and composition of organolead mixed-halide perovskites. We specifically investigate samples made by three different preparative methods: solution phase synthesis, thermal annealing, and solid phase synthesis. 207Pb ssNMR reveals that nonstoichiometric dopants and semicrystalline phases are prevalent in samples made by solution phase synthesis. We show that these nanodomains are persistent after thermal annealing up to 200 °C. Further, a novel solid phase synthesis that starts from the parent, single-halide perovskites can suppress phase segregation but not the formation of dopants. Our observations are consistent with the presence of miscibility gaps and spontaneous spinodal decomposition of the mixed-halide perovskites at room temperature. This underscores how strongly different synthetic procedures impact the nanostructuring and composition of organolead halide perovskites. In conclusion, better optoelectronic properties and improved device stability and performance may be achieved through careful manipulation of the different phases and nanodomains present in these materials.« less

Nonstoichiometry of ZnGeP 2 crystals probed by static tensimetric method

NASA Astrophysics Data System (ADS)

Vasilyeva, I. G.; Nikolaev, R. E.; Verozubova, G. A.

2010-09-01

The nonstoichiometry of ZnGeP 2 has been determined based on the p-T dependences measured above ZnP 2-Ge samples in the temperature range of 980-1225 K by a high-sensitive and precise tensimetric static method with a quartz Bourdon gauge. Scanning of the compositional range 49-51 mol% ZnP 2 in the closed system and construction of the p-T dependences were possible due to incongruent evaporation of ZnGeP 2 and formation of volatile species Zn(g), P 4(g) and P 2(g). The maximum homogeneity range of the solid ZnGeP 2 was determined between 50.03 and 49.61 mol% ZnP 2 at a temperature of 1128 K, based on the inflection points on the p-T dependences, corresponding to transitions of the three-phase (solid-solid-vapor) equilibrium to a two-phase (solid-vapor) one and vice visa. The nonstoichiometry as the overall concentration of defects is considered to gain a better insight into the defect chemistry of ZnGeP 2.

A stable perovskite electrolyte in moist air for Li-ion batteries.

PubMed

Li, Yutao; Xu, Henghui; Chien, Po-Hsiu; Wu, Nan; Xin, Sen; Xue, Leigang; Park, Kyusung; Hu, Yan-Yan; Goodenough, John B

2018-05-07

Solid-oxide Li+ electrolytes of a rechargeable cell are generally sensitive to moisture in the air, H+ exchanges for the mobile Li+ of the electrolyte and forms insulating surface phases at the electrolyte interfaces and in the grain boundaries of a polycrystalline membrane. These surface phases dominate the total interfacial resistance of a conventional rechargeable cell having a solid-electrolyte separator. We report a new perovskite Li+ solid electrolyte, Li0.38Sr0.44Ta0.7Hf0.3O2.95F0.05, having a Li-ion conductivity σLi = 4.8×10-4 S cm-1 at 25 oC that does not react with water having 3≤pH≤14. The solid electrolyte with a thin Li+-conducting polymer on its surface to prevent reduction of Ta5+ is wet by metallic lithium and provides low-impedance dendrite-free plating/stripping of a lithium anode. It is also stable on contact with a composite polymer cathode. With this solid electrolyte, we demonstrate excellent cycling performance of an all-solid-state Li/LiFePO4 cell, a Li-S cell with a polymer-gel cathode, and a supercapacitor. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hyperbranched quasi-1D nanostructures for solid-state dye-sensitized solar cells.

PubMed

Passoni, Luca; Ghods, Farbod; Docampo, Pablo; Abrusci, Agnese; Martí-Rujas, Javier; Ghidelli, Matteo; Divitini, Giorgio; Ducati, Caterina; Binda, Maddalena; Guarnera, Simone; Li Bassi, Andrea; Casari, Carlo Spartaco; Snaith, Henry J; Petrozza, Annamaria; Di Fonzo, Fabio

2013-11-26

In this work we demonstrate hyperbranched nanostructures, grown by pulsed laser deposition, composed of one-dimensional anatase single crystals assembled in arrays of high aspect ratio hierarchical mesostructures. The proposed growth mechanism relies on a two-step process: self-assembly from the gas phase of amorphous TiO2 clusters in a forest of tree-shaped hierarchical mesostructures with high aspect ratio; oriented crystallization of the branches upon thermal treatment. Structural and morphological characteristics can be optimized to achieve both high specific surface area for optimal dye uptake and broadband light scattering thanks to the microscopic feature size. Solid-state dye sensitized solar cells fabricated with arrays of hyperbranched TiO2 nanostructures on FTO-glass sensitized with D102 dye showed a significant 66% increase in efficiency with respect to a reference mesoporous photoanode and reached a maximum efficiency of 3.96% (among the highest reported for this system). This result was achieved mainly thanks to an increase in photogenerated current directly resulting from improved light harvesting efficiency of the hierarchical photoanode. The proposed photoanode overcomes typical limitations of 1D TiO2 nanostructures applied to ss-DSC and emerges as a promising foundation for next-generation high-efficiency solid-state devices comprosed of dyes, polymers, or quantum dots as sensitizers.

Surface-Accelerated Decomposition of δ-HMX.

PubMed

Sharia, Onise; Tsyshevsky, Roman; Kuklja, Maija M

2013-03-07

Despite extensive efforts to study the explosive decomposition of HMX, a cyclic nitramine widely used as a solid fuel, explosive, and propellant, an understanding of the physicochemical processes, governing the sensitivity of condensed HMX to detonation initiation is not yet achieved. Experimental and theoretical explorations of the initiation of chemistry are equally challenging because of many complex parallel processes, including the β-δ phase transition and the decomposition from both phases. Among four known polymorphs, HMX is produced in the most stable β-phase, which transforms into the most reactive δ-phase under heat or pressure. In this study, the homolytic NO2 loss and HONO elimination precursor reactions of the gas-phase, ideal crystal, and the (100) surface of δ-HMX are explored by first principles modeling. Our calculations revealed that the high sensitivity of δ-HMX is attributed to interactions of surfaces and molecular dipole moments. While both decomposition reactions coexist, the exothermic HONO-isomer formation catalyzes the N-NO2 homolysis, leading to fast violent explosions.

Multi-residue determination of 171 pesticides in cowpea using modified QuEChERS method with multi-walled carbon nanotubes as reversed-dispersive solid-phase extraction materials.

PubMed

Han, Yongtao; Song, Le; Zou, Nan; Chen, Ronghua; Qin, Yuhong; Pan, Canping

2016-09-15

A rapid and sensitive method for the determination of 171 pesticides in cowpea was developed using multi-walled carbon nanotubes (MWCNTs) as reversed-dispersive solid-phase (r-DSPE) extraction materials. The clean-up performance of MWCNTs was proved to be obviously superior to PSA and GCB. This method was validated on cowpea spiked at 0.01 and 0.1mgkg(-1) with five replicates. The mean recoveries for 169 pesticides ranged from 74% to 129% with relative standard deviations (RSDs) (n=5) lower than 16.4%, except diflufenican and quizalofop-ethyl. Good linearity for all pesticides was obtained with the calibration curve coefficients (R(2)) larger than 0.9970. The limit of detection (LODs) and limit of quantification (LOQs) for the 171 pesticides ranged from 0.001 to 0.003mgkg(-1) and from 0.002 to 0.009mgkg(-1), respectively. The method was demonstrated to be reliable and sensitive for the routine monitoring of the 171 pesticides in cowpea samples. Copyright © 2016 Elsevier B.V. All rights reserved.

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

PubMed

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

2005-06-01

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

Evaluation of the solid phase competition ELISA for detecting antibodies against the six foot-and-mouth disease virus non-O serotypes.

PubMed

Li, Yanmin; Swabey, Kate G; Gibson, Debi; Keel, Phil J; Hamblin, Pip; Wilsden, Ginette; Corteyn, Mandy; Ferris, Nigel P

2012-08-01

The solid-phase competition ELISA (SPCE) has been evaluated in both screening and titration assay formats for detecting antibodies against foot-and-mouth disease virus (FMDV) for the six non-O serotypes A, C, SAT 1, SAT 2, SAT 3 and Asia 1. Cut-off values were determined as a percentage inhibition of 40 for the SAT serotypes and 50 for serotypes A, C and Asia 1, which gave rise to specificity values ranging from 99.41% to 99.9% for the different serotypes. The relative sensitivity between the SPCE and LPBE/virus neutralisation test was 100%/109%. Antiserum titres derived by the SPCE for samples of serotypes O, A(22) and Asia 1 were more than 11, 1 and 5 times of those determined by virus neutralisation test, respectively. This study indicated that the non-type O SPCEs have sufficient sensitivities and specificities for use as serological diagnostic tests for the qualitative and quantitative detection of antibodies against FMDV. Copyright © 2012 Elsevier B.V. All rights reserved.

Determination of thallium at ultra-trace levels in water and biological samples using solid phase spectrophotometry

NASA Astrophysics Data System (ADS)

Amin, Alaa S.; El-Sharjawy, Abdel-Azeem M.; Kassem, Mohammed A.

2013-06-01

A new simple, very sensitive, selective and accurate procedure for the determination of trace amounts of thallium(III) by solid-phase spectrophotometry (SPS) has been developed. The procedure is based on fixation of Tl(III) as quinalizarin ion associate on a styrene-divinylbenzene anion-exchange resin. The absorbance of resin sorbed Tl(III) ion associate is measured directly at 636 and 830 nm. Thallium(I) was determined by difference measurements after oxidation of Tl(I) to Tl(III) with bromine. Calibration is linear over the range 0.5-12.0 μg L-1 of Tl(III) with relative standard deviation (RSD) of 1.40% (n = 10). The detection and quantification limits are 150 and 495 ng L-1 using 0.6 g of the exchanger. The molar absorptivity and Sandell sensitivity are also calculated and found to be 1.31 × 107 L mol-1 cm-1 and 0.00156 ng cm-2, respectively. The proposed procedure has been successfully applied to determine thallium in water, urine and serum samples.

Determination of thallium at ultra-trace levels in water and biological samples using solid phase spectrophotometry.

PubMed

Amin, Alaa S; El-Sharjawy, Abdel-Azeem M; Kassem, Mohammed A

2013-06-01

A new simple, very sensitive, selective and accurate procedure for the determination of trace amounts of thallium(III) by solid-phase spectrophotometry (SPS) has been developed. The procedure is based on fixation of Tl(III) as quinalizarin ion associate on a styrene-divinylbenzene anion-exchange resin. The absorbance of resin sorbed Tl(III) ion associate is measured directly at 636 and 830 nm. Thallium(I) was determined by difference measurements after oxidation of Tl(I) to Tl(III) with bromine. Calibration is linear over the range 0.5-12.0 μg L(-1) of Tl(III) with relative standard deviation (RSD) of 1.40% (n=10). The detection and quantification limits are 150 and 495 ng L(-1) using 0.6 g of the exchanger. The molar absorptivity and Sandell sensitivity are also calculated and found to be 1.31×10(7) L mol(-1)cm(-1) and 0.00156 ng cm(-2), respectively. The proposed procedure has been successfully applied to determine thallium in water, urine and serum samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Improved micromethod for mezlocillin quantitation in serum and urine by high-pressure liquid chromatography.

PubMed Central

Fiore, D; Auger, F A; Drusano, G L; Dandu, V R; Lesko, L J

1984-01-01

A rapid, sensitive, and specific method of analysis for mezlocillin in serum and urine by high-pressure liquid chromatography is described. A solid-phase extraction column was used to remove interfering substances from samples before chromatography. Quantitation included the use of an internal standard, nafcillin. Mezlocillin was chromatographed with a phosphate buffer-acetonitrile (73:27) mobile phase and a C-18 reverse-phase column and detected at a wavelength of 220 nm. The assay had a sensitivity of 1.6 micrograms/ml and a linearity of up to 600 micrograms/ml and 16 mg/ml in serum and urine, respectively, with only 0.1 ml of sample. The interday and intraday coefficients of variation for replicate analyses of spiked serum and urine specimens were less than 6.5%. PMID:6517560

Analysis of four toxic metals in a single rice seed by matrix solid phase dispersion -inductively coupled plasma mass spectrometry

NASA Astrophysics Data System (ADS)

He, Xiufen; Chen, Lixia; Chen, Xin; Yu, Huamei; Peng, Lixu; Han, Bingjun

2016-12-01

Toxic metals in rice pose great risks to human health. Metal bioaccumulation in rice grains is a criterion of breeding. Rice breeding requires a sensitive method to determine metal content in single rice grains to assist the variety selection. In the present study, four toxic metals of arsenic (As), cadmium (Cd), chromium (Cr) and lead (Pb) in a single rice grain were determined by a simple and rapid method. The developed method is based on matrix solid phase dispersion using multi-wall carbon nanotubes (MWCNTs) as dispersing agent and analyzed by inductively coupled plasma mass spectrometry. The experimental parameters were systematically investigated. The limits of detection (LOD) were 5.0, 0.6, 10 and 2.1 ng g-1 for As, Cd, Cr, and Pb, respectively, with relative standard deviations (n = 6) of <7.7%, demonstrating the good sensitivity and precision of the method. The results of 30 real world rice samples analyzed by this method agreed well with those obtained by the standard microwave digestion. The amount of sample required was reduced approximately 100 fold in comparison with the microwave digestion. The method has a high application potential for other sample matrices and elements with high sensitivity and sample throughput.

Analysis of four toxic metals in a single rice seed by matrix solid phase dispersion -inductively coupled plasma mass spectrometry.

PubMed

He, Xiufen; Chen, Lixia; Chen, Xin; Yu, Huamei; Peng, Lixu; Han, Bingjun

2016-12-06

Toxic metals in rice pose great risks to human health. Metal bioaccumulation in rice grains is a criterion of breeding. Rice breeding requires a sensitive method to determine metal content in single rice grains to assist the variety selection. In the present study, four toxic metals of arsenic (As), cadmium (Cd), chromium (Cr) and lead (Pb) in a single rice grain were determined by a simple and rapid method. The developed method is based on matrix solid phase dispersion using multi-wall carbon nanotubes (MWCNTs) as dispersing agent and analyzed by inductively coupled plasma mass spectrometry. The experimental parameters were systematically investigated. The limits of detection (LOD) were 5.0, 0.6, 10 and 2.1 ng g -1 for As, Cd, Cr, and Pb, respectively, with relative standard deviations (n = 6) of <7.7%, demonstrating the good sensitivity and precision of the method. The results of 30 real world rice samples analyzed by this method agreed well with those obtained by the standard microwave digestion. The amount of sample required was reduced approximately 100 fold in comparison with the microwave digestion. The method has a high application potential for other sample matrices and elements with high sensitivity and sample throughput.

Simultaneous extraction and determination of phthalate esters in aqueous solution by yolk-shell magnetic mesoporous carbon-molecularly imprinted composites based on solid-phase extraction coupled with gas chromatography-mass spectrometry.

PubMed

Yang, Rui; Liu, Yuxin; Yan, Xiangyang; Liu, Shaomin

2016-12-01

A rapid, sensitive and accurate method for the simultaneous extraction and determination of five types of trace phthalate esters (PAEs) in environmental water and beverage samples using magnetic molecularly imprinted solid-phase extraction (MMIP-SPE) coupled with gas chromatography-mass spectrometry (GC-MS) was developed. A novel type of molecularly imprinted polymers on the surface of yolk-shell magnetic mesoporous carbon (Fe 3 O 4 @void@C-MIPs) was used as an efficient adsorbent for selective adsorption of phthalate esters based on magnetic solid-phase extraction (MSPE). The real samples were first preconcentrated by Fe 3 O 4 @void@C-MIPs, subsequently extracted by eluent and finally determined by GC-MS after magnetic separation. Several variables affecting the extraction efficiency of the analytes, including the type and volume of the elution solvent, amount of adsorbent, extraction time, desorption time and pH of the sample solution, were investigated and optimized. Validation experiments indicated that the developed method presented good linearity (R 2 >0.9961), satisfactory precision (RSD<6.7%), and high recovery (86.1-103.1%). The limits of detection ranged from 1.6ng/L to 5.2ng/L and the enrichment factor was in the range of 822-1423. The results indicated that the novel method had the advantages of convenience, good sensitivity, and high efficiency, and it could also be successfully applied to the analysis of PAEs in real samples. Copyright © 2016. Published by Elsevier B.V.

Vapor-phase infrared spectroscopy on solid organic compounds with a pulsed resonant photoacoustic detection scheme

NASA Astrophysics Data System (ADS)

Bartlome, Richard; Fischer, Cornelia; Sigrist, Markus W.

2005-08-01

There is a great need for a low cost and sensitive method to measure infrared spectra of solid organic compounds in the gas phase. To record such spectra, we propose an optical parametric generator-based photoacoustic spectrometer, which emits in the mid-infrared fingerprint region between 3 and 4 microns. In this system, the sample is heated in a vessel before entering a home built photoacoustic cell, where the gaseous molecules are excited by a tunable laser source with a frequency repetition rate that matches the first longitudinal resonance frequency of the photocaoustic cell. In a first phase, we have focused on low-melting point stimulants such as Nikethamide, Mephentermine sulfate, Methylephedrine, Ephedrine and Pseudoephedrine. The vapor-phase spectra of these doping substances were measured between 2800 and 3100 cm-1, where fundamental C-H stretching vibrations take place. Our spectra show notable differences with commercially available condensed phase spectra. Our scheme enables to measure very low vapor pressures of low-melting point (<160 °C) solid organic compounds. Furthermore, the optical resolution of 8 cm-1 is good enough to distinguish closely related chemical structures such as the Ephedra alkaloids Ephedrine and Methylephedrine, but doesn't allow to differentiate diastereoisomeric pairs such as Ephedrine and Pseudoephedrine, two important neurotransmitters which reveal different biological activities. Therefore, higher resolution and a system capable of measuring organic compounds with higher melting points are required.

Solid-phase extraction assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplet to determine sildenafil and its analogues in dietary supplements.

PubMed

Li, Jing; Roh, Si Hun; Shaodong, Jia; Hong, Ji Yeon; Lee, Dong-Kyu; Shin, Byong-Kyu; Park, Jeong Hill; Lee, Jeongmi; Kwon, Sung Won

2017-08-01

A novel analytical method for the simultaneous determination of the concentration of sildenafil and its five analogues in dietary supplements using solid-phase extraction assisted reversed-phase dispersive liquid-liquid microextraction based on solidification of floating organic droplet combined with ion-pairing liquid chromatography with an ultraviolet detector was developed. Parameters that affect extraction efficiency were systematically investigated, including the type of solid-phase extraction cartridge, pH of the extraction environment, and the type and volume of extraction and dispersive solvent. The method linearity was in the range of 5.0-100 ng/mL for sildenafil, homosildenafil, udenafil, benzylsildenafil, and thiosildenafil and 10-100 ng/mL for acetildenafil. The coefficients of determination were ≥0.996 for all regression curves. The sensitivity values expressed as limit of detection were between 2.5 and 7.5 ng/mL. Furthermore, intraday and interday precisions expressed as relative standard deviations were less than 5.7 and 9.9%, respectively. The proposed method was successfully applied to the analysis of sildenafil and its five analogues in complex dietary supplements. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison between solid phase microextraction (SPME) and hollow fiber liquid phase microextraction (HFLPME) for determination of extractables from post-consumer recycled PET into food simulants.

PubMed

Oliveira, Éder Costa; Echegoyen, Yolanda; Cruz, Sandra Andrea; Nerin, Cristina

2014-09-01

Hollow fiber liquid phase microextraction (HFLPME) and solid phase microextraction (SPME) methods for pre-concentration of contaminants (toluene, benzophenone, tetracosane and chloroform) in food simulants were investigated. For HFLPME 1-heptanol, 2-octanone and dibutyl-ether were studied as extracting solvents. Analysis by gas chromatography coupled to mass spectrometry (GC-MS), flame ionization (GC-FID) and electron capture detectors (GC-ECD) were carried out. In addition, the methods were employed to evaluate the safety in use of a PET material after the recycling process (comprising washing, extrusion and solid state polymerization (SSP)) through extractability studies of the contaminants using 10% (v/v) ethanol in deionized water and 3% (w/v) acetic acid in deionized water as food simulants in different conditions: 10 days at 40°C and 2h at 70°C. The HFLPME preconcentration method provided increased sensitivity when compared to the SPME method and allowed to analyze concentration levels below 10 µg surrogate per kg food simulant. The results of the extractability studies showed considerable reductions after the extrusion and SSP processes and indicated the compliance with regulations for using recycled PET in contact with food. Copyright © 2014 Elsevier B.V. All rights reserved.

Development of a sensitive methodology for the analysis of chlorobenzenes in air by combination of solid-phase extraction and headspace solid-phase microextraction.

PubMed

Barro, Ruth; Ares, Sergio; Garcia-Jares, Carmen; Llompart, Maria; Cela, Rafael

2004-08-06

In this study, a combination of solid-phase extraction (SPE) and solid-phase microextraction (SPME) has been used to determine chlorobenzenes in air. Analytes were sampled by pumping a known volume of air through a porous polymer (Tenax TA). Then, the adsorbent was transferred into a glass vial and SPME was performed. The quantification was carried out using gas chromatography (GC)-electron-capture detection or GC-MS. Several SPME coatings (100 microm poly(dimethylsiloxane) (PDMS), 75 microm Carboxen (CAR)-PDMS, 65 microm PDMS-divinylbenzene (DVB), 65 microm PDMS-DVB and 85 microm polyacrylate (PA) were evaluated, obtaining the highest responses with Carbowax (CW)- PDMS for the most volatile chlorobenzenes, and with PDMS-DVB or CW-DVB fibers for the semivolatile compounds. To optimize some other factors that could affect the SPME step, a factorial design was used. Kinetic studies of the SPME process were also performed. Concerning the SPE step, breakthrough was studied, showing that 2.5 m3 of air could be processed without losses of the most volatile compounds. The performance of the method was evaluated. External calibration, which does not require the complete sampling process, demonstrated to be suitable, obtaining good linearity (R2 > 0.99) for all chlorobenzenes. Recovery studies were performed at two concentration levels (4 and 40 ng/m3), obtaining quantitative recoveries (>80%). Limits of detection at the sub ng/m3 were achieved for all the target compounds.

Shape and Symmetry Determine Two-Dimensional Melting Transitions of Hard Regular Polygons

NASA Astrophysics Data System (ADS)

Anderson, Joshua A.; Antonaglia, James; Millan, Jaime A.; Engel, Michael; Glotzer, Sharon C.

2017-04-01

The melting transition of two-dimensional systems is a fundamental problem in condensed matter and statistical physics that has advanced significantly through the application of computational resources and algorithms. Two-dimensional systems present the opportunity for novel phases and phase transition scenarios not observed in 3D systems, but these phases depend sensitively on the system and, thus, predicting how any given 2D system will behave remains a challenge. Here, we report a comprehensive simulation study of the phase behavior near the melting transition of all hard regular polygons with 3 ≤n ≤14 vertices using massively parallel Monte Carlo simulations of up to 1 ×106 particles. By investigating this family of shapes, we show that the melting transition depends upon both particle shape and symmetry considerations, which together can predict which of three different melting scenarios will occur for a given n . We show that systems of polygons with as few as seven edges behave like hard disks; they melt continuously from a solid to a hexatic fluid and then undergo a first-order transition from the hexatic phase to the isotropic fluid phase. We show that this behavior, which holds for all 7 ≤n ≤14 , arises from weak entropic forces among the particles. Strong directional entropic forces align polygons with fewer than seven edges and impose local order in the fluid. These forces can enhance or suppress the discontinuous character of the transition depending on whether the local order in the fluid is compatible with the local order in the solid. As a result, systems of triangles, squares, and hexagons exhibit a Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) predicted continuous transition between isotropic fluid and triatic, tetratic, and hexatic phases, respectively, and a continuous transition from the appropriate x -atic to the solid. In particular, we find that systems of hexagons display continuous two-step KTHNY melting. In contrast, due to symmetry incompatibility between the ordered fluid and solid, systems of pentagons and plane-filling fourfold pentilles display a one-step first-order melting of the solid to the isotropic fluid with no intermediate phase.

Using Environment-Sensitive Fluorescent Probes to Characterize Liquid-Liquid Phase Separation in Supersaturated Solutions of Poorly Water Soluble Compounds.

PubMed

Raina, Shweta A; Alonzo, David E; Zhang, Geoff G Z; Gao, Yi; Taylor, Lynne S

2015-11-01

Highly supersaturated aqueous solutions of poorly soluble compounds can undergo liquid-liquid phase separation (LLPS) when the concentration exceeds the "amorphous solubility". This phenomenon has been widely observed during high throughput screening of new molecular entities as well as during the dissolution of amorphous solid dispersions. In this study, we have evaluated the use of environment-sensitive fluorescence probes to investigate the formation and properties of the non-crystalline drug-rich aggregates formed in aqueous solutions as a result of LLPS. Six different environment-sensitive fluorophores were employed to study LLPS in highly supersaturated solutions of several model compounds, all dihydropyridine derivatives. Each fluoroprobe exhibited a large hypsochromic shift with decreasing environment polarity. Upon drug aggregate formation, the probes partitioned into the drug-rich phase and exhibited changes in emission wavelength and intensity consistent with sensing a lower polarity environment. The LLPS onset concentrations determined using the fluorescence measurements were in good agreement with light scattering measurements as well as theoretically estimated amorphous solubility values. Environment-sensitive fluorescence probes are useful to help understand the phase behavior of highly supersaturated aqueous solutions, which in turn is important in the context of developing enabling formulations for poorly soluble compounds.

End-Member Formulation of Solid Solutions and Reactive Transport

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

Lichtner, Peter C.

2015-09-01

A model for incorporating solid solutions into reactive transport equations is presented based on an end-member representation. Reactive transport equations are solved directly for the composition and bulk concentration of the solid solution. Reactions of a solid solution with an aqueous solution are formulated in terms of an overall stoichiometric reaction corresponding to a time-varying composition and exchange reactions, equivalent to reaction end-members. Reaction rates are treated kinetically using a transition state rate law for the overall reaction and a pseudo-kinetic rate law for exchange reactions. The composition of the solid solution at the onset of precipitation is assumed tomore » correspond to the least soluble composition, equivalent to the composition at equilibrium. The stoichiometric saturation determines if the solid solution is super-saturated with respect to the aqueous solution. The method is implemented for a simple prototype batch reactor using Mathematica for a binary solid solution. Finally, the sensitivity of the results on the kinetic rate constant for a binary solid solution is investigated for reaction of an initially stoichiometric solid phase with an undersaturated aqueous solution.« less

Microvolume trace environmental analysis using peak-focusing online solid-phase extraction-nano-liquid chromatography-high-resolution mass spectrometry.

PubMed

Stravs, Michael A; Mechelke, Jonas; Ferguson, P Lee; Singer, Heinz; Hollender, Juliane

2016-03-01

Online solid-phase extraction was combined with nano-liquid chromatography coupled to high-resolution mass spectrometry (HRMS) for the analysis of micropollutants in environmental samples from small volumes. The method was validated in surface water, Microcystis aeruginosa cell lysate, and spent Microcystis growth medium. For 41 analytes, quantification limits of 0.1-28 ng/L (surface water) and 0.1-32 ng/L (growth medium) were obtained from only 88 μL of sample. In cell lysate, quantification limits ranged from 0.1-143 ng/L or 0.33-476 ng/g dry weight from a sample of 88 μL, or 26 μg dry weight, respectively. The method matches the sensitivity of established online and offline solid-phase extraction-liquid chromatography-mass spectrometry methods but requires only a fraction of the sample used by those techniques, and is among the first applications of nano-LC-MS for environmental analysis. The method was applied to the determination of bioconcentration in Microcystis aeruginosa in a laboratory experiment, and the benefit of coupling to HRMS was demonstrated in a transformation product screening.

Sensitive Quantification of Cannabinoids in Milk by Alkaline Saponification-Solid Phase Extraction Combined with Isotope Dilution UPLC-MS/MS.

PubMed

Wei, Binnian; McGuffey, James E; Blount, Benjamin C; Wang, Lanqing

2016-01-01

Maternal exposure to marijuana during the lactation period-either active or passive-has prompted concerns about transmission of cannabinoids to breastfed infants and possible subsequent adverse health consequences. Assessing these health risks requires a sensitive analytical approach that is able to quantitatively measure trace-level cannabinoids in breast milk. Here, we describe a saponification-solid phase extraction approach combined with ultra-high-pressure liquid chromatography-tandem mass spectrometry for simultaneously quantifying Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabinol (CBN) in breast milk. We demonstrate for the first time that constraints on sensitivity can be overcome by utilizing alkaline saponification of the milk samples. After extensively optimizing the saponification procedure, the validated method exhibited limits of detections of 13, 4, and 66 pg/mL for THC, CBN, and CBD, respectively. Notably, the sensitivity achieved was significantly improved, for instance, the limits of detection for THC is at least 100-fold more sensitive compared to that previously reported in the literature. This is essential for monitoring cannabinoids in breast milk resulting from passive or nonrecent active maternal exposure. Furthermore, we simultaneously acquired multiple reaction monitoring transitions for 12 C- and 13 C-analyte isotopes. This combined analysis largely facilitated data acquisition by reducing the repetitive analysis rate for samples exceeding the linear limits of 12 C-analytes. In addition to high sensitivity and broad quantitation range, this method delivers excellent accuracy (relative error within ±10%), precision (relative standard deviation <10%), and efficient analysis. In future studies, we expect this method to play a critical role in assessing infant exposure to cannabinoids through breastfeeding.

Ultrafast electron and energy transfer in dye-sensitized iron oxide and oxyhydroxide nanoparticles.

PubMed

Gilbert, Benjamin; Katz, Jordan E; Huse, Nils; Zhang, Xiaoyi; Frandsen, Cathrine; Falcone, Roger W; Waychunas, Glenn A

2013-10-28

An emerging area in chemical science is the study of solid-phase redox reactions using ultrafast time-resolved spectroscopy. We have used molecules of the photoactive dye 2',7'-dichlorofluorescein (DCF) anchored to the surface of iron(III) oxide nanoparticles to create iron(II) surface atoms via photo-initiated interfacial electron transfer. This approach enables time-resolved study of the fate and mobility of electrons within the solid phase. However, complete analysis of the ultrafast processes following dye photoexcitation of the sensitized iron(III) oxide nanoparticles has not been reported. We addressed this topic by performing femtosecond transient absorption (TA) measurements of aqueous suspensions of uncoated and DCF-sensitized iron oxide and oxyhydroxide nanoparticles, and an aqueous iron(III)-dye complex. Following light absorption, excited state relaxation times of the dye of 115-310 fs were found for all samples. Comparison between TA dynamics on uncoated and dye-sensitized hematite nanoparticles revealed the dye de-excitation pathway to consist of a competition between electron and energy transfer to the nanoparticles. We analyzed the TA data for hematite nanoparticles using a four-state model of the dye-sensitized system, finding electron and energy transfer to occur on the same ultrafast timescale. The interfacial electron transfer rates for iron oxides are very close to those previously reported for DCF-sensitized titanium dioxide (for which dye-oxide energy transfer is energetically forbidden) even though the acceptor states are different. Comparison of the alignment of the excited states of the dye and the unoccupied states of these oxides showed that the dye injects into acceptor states of different symmetry (Ti t2gvs. Fe eg).

TANK48 CFD MODELING ANALYSIS

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

Lee, S.

2011-05-17

The process of recovering the waste in storage tanks at the Savannah River Site (SRS) typically requires mixing the contents of the tank to ensure uniformity of the discharge stream. Mixing is accomplished with one to four dual-nozzle slurry pumps located within the tank liquid. For the work, a Tank 48 simulation model with a maximum of four slurry pumps in operation has been developed to estimate flow patterns for efficient solid mixing. The modeling calculations were performed by using two modeling approaches. One approach is a single-phase Computational Fluid Dynamics (CFD) model to evaluate the flow patterns and qualitativemore » mixing behaviors for a range of different modeling conditions since the model was previously benchmarked against the test results. The other is a two-phase CFD model to estimate solid concentrations in a quantitative way by solving the Eulerian governing equations for the continuous fluid and discrete solid phases over the entire fluid domain of Tank 48. The two-phase results should be considered as the preliminary scoping calculations since the model was not validated against the test results yet. A series of sensitivity calculations for different numbers of pumps and operating conditions has been performed to provide operational guidance for solids suspension and mixing in the tank. In the analysis, the pump was assumed to be stationary. Major solid obstructions including the pump housing, the pump columns, and the 82 inch central support column were included. The steady state and three-dimensional analyses with a two-equation turbulence model were performed with FLUENT{trademark} for the single-phase approach and CFX for the two-phase approach. Recommended operational guidance was developed assuming that local fluid velocity can be used as a measure of sludge suspension and spatial mixing under single-phase tank model. For quantitative analysis, a two-phase fluid-solid model was developed for the same modeling conditions as the single-phase model. The modeling results show that the flow patterns driven by four pump operation satisfy the solid suspension requirement, and the average solid concentration at the plane of the transfer pump inlet is about 12% higher than the tank average concentrations for the 70 inch tank level and about the same as the tank average value for the 29 inch liquid level. When one of the four pumps is not operated, the flow patterns are satisfied with the minimum suspension velocity criterion. However, the solid concentration near the tank bottom is increased by about 30%, although the average solid concentrations near the transfer pump inlet have about the same value as the four-pump baseline results. The flow pattern results show that although the two-pump case satisfies the minimum velocity requirement to suspend the sludge particles, it provides the marginal mixing results for the heavier or larger insoluble materials such as MST and KTPB particles. The results demonstrated that when more than one jet are aiming at the same position of the mixing tank domain, inefficient flow patterns are provided due to the highly localized momentum dissipation, resulting in inactive suspension zone. Thus, after completion of the indexed solids suspension, pump rotations are recommended to avoid producing the nonuniform flow patterns. It is noted that when tank liquid level is reduced from the highest level of 70 inches to the minimum level of 29 inches for a given number of operating pumps, the solid mixing efficiency becomes better since the ratio of the pump power to the mixing volume becomes larger. These results are consistent with the literature results.« less

SOLID PHASE EXTRACTION AND HIGH PERFORMANCE LIQUID CHROMATOGRAPHY WITH PHOTODIODE ARRAY DETECTION OF CHEMICAL INDICATORS OF HUMAN FECAL CONTAMINATION IN WATER

EPA Science Inventory

Faster and more sensitive analysis of water that is contaminated by human fecal matter is very important for health. The current microbiological methods to assess water quality do not meet this need. Alternate non-microbial human fecal indicators have been proposed by various r...

ON SITE SOLID-PHASE EXTRACTION AND LABORATORY ANALYSIS OF ULTRA-TRACE SYNTHETIC MUSKS IN MUNICIPAL SEWAGE EFFLUENT USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY. FULL-SCAN MODE

EPA Science Inventory

Fragrance materials such as synthetic musks in aqueous samples, are normally determined by gas chromatography/mass spectrometry in the selected ion monitoring (SIM) mode to provide maximum sensitivity after liquid-liquid extraction of I -L samples. Full-scan mass spectra are requ...

Transient Numerical Modeling of Catalytic Channels

NASA Technical Reports Server (NTRS)

Struk, Peter M.; Dietrich, Daniel L.; Miller, Fletcher J.; T'ien, James S.

2007-01-01

This paper presents a transient model of catalytic combustion suitable for isolated channels and monolith reactors. The model is a lumped two-phase (gas and solid) model where the gas phase is quasi-steady relative to the transient solid. Axial diffusion is neglected in the gas phase; lateral diffusion, however, is accounted for using transfer coefficients. The solid phase includes axial heat conduction and external heat loss due to convection and radiation. The combustion process utilizes detailed gas and surface reaction models. The gas-phase model becomes a system of stiff ordinary differential equations while the solid phase reduces, after discretization, into a system of stiff ordinary differential-algebraic equations. The time evolution of the system came from alternating integrations of the quasi-steady gas and transient solid. This work outlines the numerical model and presents some sensitivity studies on important parameters including internal transfer coefficients, catalytic surface site density, and external heat-loss (if applicable). The model is compared to two experiments using CO fuel: (1) steady-state conversion through an isothermal platinum (Pt) tube and (2) transient propagation of a catalytic reaction inside a small Pt tube. The model requires internal mass-transfer resistance to match the experiments at lower residence times. Under mass-transport limited conditions, the model reasonably predicted exit conversion using global mass-transfer coefficients. Near light-off, the model results did not match the experiment precisely even after adjustment of mass-transfer coefficients. Agreement improved for the first case after adjusting the surface kinetics such that the net rate of CO adsorption increased compared to O2. The CO / O2 surface mechanism came from a sub-set of reactions in a popular CH4 / O2 mechanism. For the second case, predictions improved for lean conditions with increased external heat loss or adjustment of the kinetics as in the first case. Finally, the results show that different initial surface-species distribution leads to different steady-states under certain conditions. These results demonstrate the utility of a lumped two-phase model of a transient catalytic combustor with detailed chemistry.

Non-invasive analysis of swelling in polymer dispersions by means of time-domain(TD)-NMR.

PubMed

Nestle, Nikolaus; Häberle, Karl

2009-11-03

In this contribution, we discuss the potential of low-field time-domain(TD)-NMR to study the swelling of (aqueous) polymer dispersions by a volatile solvent. Due to the sensitivity of transverse relaxation times (T2) to swelling-induced changes in the molecular dynamics of the polymer component, the effects of swelling can be measured without spectral resolution. The measurement is performed on polymer dispersions in native state with solids contents around 50% in a non-invasive way without separating the polymeric phase and the water phase from each other. Using acetone in two polyurethane (PU) dispersions with different hard phase contents, we explore the sensitivity of the method and present a data evaluation strategy based on multicomponent fitting and proton balancing. Furthermore, we report exchange continualization as a further effect that needs to be taken into account for correct interpretation of the data.

A simple, sensitive determination of ganciclovir in infant plasma by high-performance liquid chromatography with fluorescence detection.

PubMed

Yoshida, Terumitsu; Takahashi, Ryohei; Imai, Koichi; Uchida, Hiroshi; Arai, Yasutoshi; Oh-ishi, Tsutomu

2010-03-01

This study developed a simple and sensitive method using reversed-phase high-performance liquid chromatography (HPLC) for ganciclovir (GCV) plasma concentrations in cytomegalovirus infectious infants with hearing loss. The method involves a simple protein precipitation procedure that uses no solid-phase or liquid-liquid extraction. The HPLC separation was carried out on a Cadenza CD-C(18) column (3 microm, 4.6 mm x 150 mm) with phosphate buffer (pH 2.5, 25 mM) containing 1% methanol-acetonitrile mixture (4:3, v/v) as a mobile phase at a 0.7 mL/min flow rate. GCV was detected using a fluorescence detection (lambdaex/em: 265/380 nm). The quantification limit was 0.025 microg/mL for 100 microL of plasma sample at which good intra- and inter-assay coefficient of variation values (< 4.96%) and recoveries (94.9-96.5%) were established.

Experimental limits on the fidelity of adiabatic geometric phase gates in a single solid-state spin qubit

DOE PAGES

Zhang, Kai; Nusran, N. M.; Slezak, B. R.; ...

2016-05-17

While it is often thought that the geometric phase is less sensitive to fluctuations in the control fields, a very general feature of adiabatic Hamiltonians is the unavoidable dynamic phase that accompanies the geometric phase. The effect of control field noise during adiabatic geometric quantum gate operations has not been probed experimentally, especially in the canonical spin qubit system that is of interest for quantum information. We present measurement of the Berry phase and carry out adiabatic geometric phase gate in a single solid-state spin qubit associated with the nitrogen-vacancy center in diamond. We manipulate the spin qubit geometrically bymore » careful application of microwave radiation that creates an effective rotating magnetic field, and observe the resulting Berry phase signal via spin echo interferometry. Our results show that control field noise at frequencies higher than the spin echo clock frequency causes decay of the quantum phase, and degrades the fidelity of the geometric phase gate to the classical threshold after a few (~10) operations. This occurs in spite of the geometric nature of the state preparation, due to unavoidable dynamic contributions. In conclusion, we have carried out systematic analysis and numerical simulations to study the effects of the control field noise and imperfect driving waveforms on the quantum phase gate.« less

Experimental limits on the fidelity of adiabatic geometric phase gates in a single solid-state spin qubit

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

Zhang, Kai; Nusran, N. M.; Slezak, B. R.

While it is often thought that the geometric phase is less sensitive to fluctuations in the control fields, a very general feature of adiabatic Hamiltonians is the unavoidable dynamic phase that accompanies the geometric phase. The effect of control field noise during adiabatic geometric quantum gate operations has not been probed experimentally, especially in the canonical spin qubit system that is of interest for quantum information. We present measurement of the Berry phase and carry out adiabatic geometric phase gate in a single solid-state spin qubit associated with the nitrogen-vacancy center in diamond. We manipulate the spin qubit geometrically bymore » careful application of microwave radiation that creates an effective rotating magnetic field, and observe the resulting Berry phase signal via spin echo interferometry. Our results show that control field noise at frequencies higher than the spin echo clock frequency causes decay of the quantum phase, and degrades the fidelity of the geometric phase gate to the classical threshold after a few (~10) operations. This occurs in spite of the geometric nature of the state preparation, due to unavoidable dynamic contributions. In conclusion, we have carried out systematic analysis and numerical simulations to study the effects of the control field noise and imperfect driving waveforms on the quantum phase gate.« less

Determination of Trace Available Heavy Metals in Soil Using Laser-Induced Breakdown Spectroscopy Assisted with Phase Transformation Method.

PubMed

Yi, Rongxing; Yang, Xinyan; Zhou, Ran; Li, Jiaming; Yu, Huiwu; Hao, Zhongqi; Guo, Lianbo; Li, Xiangyou; Lu, Yongfeng; Zeng, Xiaoyan

2018-05-18

To detect available heavy metals in soil using laser-induced breakdown spectroscopy (LIBS) and improve its poor detection sensitivity, a simple and low cost sample pretreatment method named solid-liquid-solid transformation was proposed. By this method, available heavy metals were extracted from soil through ultrasonic vibration and centrifuging and then deposited on a glass slide. Utilization of this solid-liquid-solid transformation method, available Cd and Pb elements in soil were detected successfully. The results show that the regression coefficients of calibration curves for soil analyses reach to more than 0.98. The limits of detection could reach to 0.067 and 0.94 ppm for available Cd and Pb elements in soil under optimized conditions, respectively, which are much better than those obtained by conventional LIBS.

Transient Catalytic Combustor Model With Detailed Gas and Surface Chemistry

NASA Technical Reports Server (NTRS)

Struk, Peter M.; Dietrich, Daniel L.; Mellish, Benjamin P.; Miller, Fletcher J.; Tien, James S.

2005-01-01

In this work, we numerically investigate the transient combustion of a premixed gas mixture in a narrow, perfectly-insulated, catalytic channel which can represent an interior channel of a catalytic monolith. The model assumes a quasi-steady gas-phase and a transient, thermally thin solid phase. The gas phase is one-dimensional, but it does account for heat and mass transfer in a direction perpendicular to the flow via appropriate heat and mass transfer coefficients. The model neglects axial conduction in both the gas and in the solid. The model includes both detailed gas-phase reactions and catalytic surface reactions. The reactants modeled so far include lean mixtures of dry CO and CO/H2 mixtures, with pure oxygen as the oxidizer. The results include transient computations of light-off and system response to inlet condition variations. In some cases, the model predicts two different steady-state solutions depending on whether the channel is initially hot or cold. Additionally, the model suggests that the catalytic ignition of CO/O2 mixtures is extremely sensitive to small variations of inlet equivalence ratios and parts per million levels of H2.

Preparation of a novel hyperbranched carbosilane-silica hybrid coating for trace amount detection by solid phase microextraction/gas chromatography.

PubMed

Chen, Guowen; Li, Wenjie; Zhang, Chen; Zhou, Chuanjian; Feng, Shengyu

2012-09-21

Phenyl-ended hyperbranched carbosilane (HBC) is synthesized and immobilized onto the inner wall of a fused silica capillary column using a sol-gel process. The hybrid coating layer formed is used as a stationary phase for gas chromatography (GC) and as an adsorption medium for solid phase microextraction (SPME). Trifluoroacetic acid, as a catalyst in this process, helps produce a homogeneous hybrid coating layer. This result is beneficial for better column chromatographic performances, such as high efficiency and high resolution. Extraction tests using the novel hybrid layer show an extraordinarily large adsorption capacity and specific adsorption behavior for aromatic compounds. A 1 ppm trace level detectability is obtained with the SPME/GC work model when both of the stationary phase and adsorption layer bear a hyperbranched structure. A large amount of phenyl groups and a low viscosity of hyperbranched polymers contribute to these valuable properties, which are important to environment and safety control, wherein detection sensitivity and special adsorption behavior are usually required. Copyright © 2012 Elsevier B.V. All rights reserved.

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

Vasilyeva, I.G., E-mail: kamarz@niic.nsc.r; Nikolaev, R.E.; Verozubova, G.A.

Abstracts: The nonstoichiometry of ZnGeP{sub 2} has been determined based on the p-T dependences measured above ZnP{sub 2}-Ge samples in the temperature range of 980-1225 K by a high-sensitive and precise tensimetric static method with a quartz Bourdon gauge. Scanning of the compositional range 49-51 mol% ZnP{sub 2} in the closed system and construction of the p-T dependences were possible due to incongruent evaporation of ZnGeP{sub 2} and formation of volatile species Zn(g), P{sub 4}(g) and P{sub 2}(g). The maximum homogeneity range of the solid ZnGeP{sub 2} was determined between 50.03 and 49.61 mol% ZnP{sub 2} at a temperature ofmore » 1128 K, based on the inflection points on the p-T dependences, corresponding to transitions of the three-phase (solid-solid-vapor) equilibrium to a two-phase (solid-vapor) one and vice visa. The nonstoichiometry as the overall concentration of defects is considered to gain a better insight into the defect chemistry of ZnGeP{sub 2}. - Graphical abstract: The nonstoichiometry of ZnGeP{sub 2} on the T-x diagram of the ZnP{sub 2}-Ge system.« less

A sensitive analytical procedure for monitoring acrylamide in environmental water samples by offline SPE-UPLC/MS/MS.

PubMed

Togola, Anne; Coureau, Charlotte; Guezennec, Anne-Gwenaëlle; Touzé, Solène

2015-05-01

The presence of acrylamide in natural systems is of concern from both environmental and health points of view. We developed an accurate and robust analytical procedure (offline solid phase extraction combined with UPLC/MS/MS) with a limit of quantification (20 ng L(-1)) compatible with toxicity threshold values. The optimized (considering the nature of extraction phases, sampling volumes, and solvent of elution) solid phase extraction (SPE) was validated according to ISO Standard ISO/IEC 17025 on groundwater, surface water, and industrial process water samples. Acrylamide is highly polar, which induces a high variability during the SPE step, therefore requiring the use of C(13)-labeled acrylamide as an internal standard to guarantee the accuracy and robustness of the method (uncertainty about 25 % (k = 2) at limit of quantification level). The specificity of the method and the stability of acrylamide were studied for these environmental media, and it was shown that the method is suitable for measuring acrylamide in environmental studies.

Determination of some volatile compounds in alcoholic beverage by headspace solid-phase microextraction gas chromatography - mass spectrometry

NASA Astrophysics Data System (ADS)

Schmutzer, G.; Avram, V.; Feher, I.; David, L.; Moldovan, Z.

2012-02-01

The volatile composition of alcoholic beverage was studied by headspace solid-phase microextraction (HSSPME) method and gas chromatography - mass spectrometry (GC-MS). Some volatile compounds, such as alcohols, esters, terpenes and other are mainly responsible for the flavor of fortified wines and their amounts specify the quality of the alcoholic beverages. From this perspective it is interesting to develop a rapid, selective and sensitive analytical method suitable for simultaneous quantification of the main molecules being responsible for the organoleptic characteristic of alcoholic beverages. Vermouth fortified drink was analyzed in order to characterize the volatile profile. Using the HS-SPME/GC-MS a number of twenty-six volatile compounds from a commercial market alcoholic beverage were identified. The most abundant compounds were m-thymol, o-thymol and eugenol, alongside of the ethyl ester compounds.

Determination of Low Concentrations of Acetochlor in Water by Automated Solid-Phase Extraction and Gas Chromatography with Mass-Selective Detection

USGS Publications Warehouse

Lindley, C.E.; Stewart, J.T.; Sandstrom, M.W.

1996-01-01

A sensitive and reliable gas chromatographic/mass spectrometric (GC/MS) method for determining acetochlor in environmental water samples was developed. The method involves automated extraction of the herbicide from a filtered 1 L water sample through a C18 solid-phase extraction column, elution from the column with hexane-isopropyl alcohol (3 + 1), and concentration of the extract with nitrogen gas. The herbicide is quantitated by capillary/column GC/MS with selected-ion monitoring of 3 characteristic ions. The single-operator method detection limit for reagent water samples is 0.0015 ??g/L. Mean recoveries ranged from about 92 to 115% for 3 water matrixes fortified at 0.05 and 0.5 ??g/L. Average single-operator precision, over the course of 1 week, was better than 5%.

Solid-phase microextraction technology for in vitro and in vivo metabolite analysis

PubMed Central

Zhang, Qihui; Zhou, Liandi; Chen, Hua; Wang, Chong-Zhi; Xia, Zhining; Yuan, Chun-Su

2016-01-01

Analysis of endogenous metabolites in biological samples may lead to the identification of biomarkers in metabolomics studies. To achieve accurate sample analysis, a combined method of continuous quick sampling and extraction is required for online compound detection. Solid-phase microextraction (SPME) integrates sampling, extraction and concentration into a single solvent-free step for chemical analysis. SPME has a number of advantages, including simplicity, high sensitivity and a relatively non-invasive nature. In this article, we reviewed SPME technology in in vitro and in vivo analyses of metabolites after the ingestion of herbal medicines, foods and pharmaceutical agents. The metabolites of microorganisms in dietary supplements and in the gastrointestinal tract will also be examined. As a promising technology in biomedical and pharmaceutical research, SPME and its future applications will depend on advances in analytical technologies and material science. PMID:27695152

Optimization of total vaporization solid-phase microextraction (TV-SPME) for the determination of lipid profiles of Phormia regina, a forensically important blow fly species.

PubMed

Kranz, William; Carroll, Clinton; Dixon, Darren; Picard, Christine; Goodpaster, John

2017-11-01

A new method has been developed for the determination of fatty acids, sterols, and other lipids which naturally occur within pupae of the blow fly Phormia regina. The method relies upon liquid extraction in non-polar solvent, followed by derivatization using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) w/ 1% trimethylchlorsilane (TMCS) carried out inside the sample vial. The analysis is facilitated by total vaporization solid-phase microextraction (TV-SPME), with gas chromatography-mass spectrometry (GC-MS) serving as the instrumentation for analysis. The TV-SPME delivery technique is approximately a factor of five more sensitive than traditional liquid injection, which may alleviate the need for rotary evaporation, reconstitution, collection of high performance liquid chromatography fractions, and many of the other pre-concentration steps that are commonplace in the current literature. Furthermore, the ability to derivatize the liquid extract in a single easy step while increasing sensitivity represents an improvement over current derivatization methods. The most common lipids identified in fly pupae were various saturated and unsaturated fatty acids ranging from lauric acid (12:0) to arachinoic acid (20:4), as well as cholesterol. The concentrations of myristic acid (14:0), palmitelaidic acid (16:2), and palmitoleic acid (16:1) were the most reliable indicators of the age of the pupae. Graphical abstract Blow fly pupae were extracted prior to emerging as adults. The extracts were analyzed via total vaporization solid-phase microextraction (TV-SPME), revealing a complex mixture of lipids that could be associated with the age of the insect. This information may assist in determining a post-mortum interval (PMI) in a death investigation.

In-line micro-matrix solid-phase dispersion extraction for simultaneous separation and extraction of Sudan dyes in different spices.

PubMed

Rajabi, Maryam; Sabzalian, Sedigheh; Barfi, Behruz; Arghavani-Beydokhti, Somayeh; Asghari, Alireza

2015-12-18

A novel, simple, fast, and miniaturized method, termed in-line micro-matrix solid-phase dispersion (in-line MMSPD), coupled with high performance liquid chromatography (HPLC) was developed for the simultaneous extraction and determination of Sudan dyes (i.e. Sudan I-IV, Sudan orange G, Sudan black B, and Sudan red G) with the aid of an experimental design strategy. In this method, a matrix solid-phase dispersion (MSPD) column including a suitable mixture of polar sorbents was inserted in the mobile phase pathway, and while the interfering compounds were retained, the analytes were eluted and entered into the analytical column. In this way, the extraction, elution, and separation of the analytes were performed sequentially. Under the optimal experimental conditions (including the amount of sample, 0.0426g; amount of dispersant phase, 0.0216g of florisil, 0.0227g of silica, 0.0141g of alumina; and blending time, 112s), the limits of detection (LODs), limits of quantification, linear dynamic ranges, and recoveries were obtained to be 0.3-15.3μgkg(-1), 1-50μgkg(-1), 50-28,000μgkg(-1), and 94.5-99.1%, respectively. The results obtained showed that determination of the selected Sudan dyes in food samples using an enough sensitive and a simple analytically validated method like in-line MMSPD may offer a suitable screening method, which could be useful for food analysis and adulteration. Copyright © 2015 Elsevier B.V. All rights reserved.

Automated solid-phase extraction of phenolic acids using layered double hydroxide-alumina-polymer disks.

PubMed

Ghani, Milad; Palomino Cabello, Carlos; Saraji, Mohammad; Manuel Estela, Jose; Cerdà, Víctor; Turnes Palomino, Gemma; Maya, Fernando

2018-01-26

The application of layered double hydroxide-Al 2 O 3 -polymer mixed-matrix disks for solid-phase extraction is reported for the first time. Al 2 O 3 is embedded in a polymer matrix followed by an in situ metal-exchange process to obtain a layered double hydroxide-Al 2 O 3 -polymer mixed-matrix disk with excellent flow-through properties. The extraction performance of the prepared disks is evaluated as a proof of concept for the automated extraction using sequential injection analysis of organic acids (p-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid, gallic acid) following an anion-exchange mechanism. After the solid-phase extraction, phenolic acids were quantified by reversed-phase high-performance liquid chromatography with diode-array detection using a core-shell silica-C18 stationary phase and isocratic elution (acetonitrile/0.5% acetic acid in pure water, 5:95, v/v). High sensitivity and reproducibility were obtained with limits of detection in the range of 0.12-0.25 μg/L (sample volume, 4 mL), and relative standard deviations between 2.9 and 3.4% (10 μg/L, n = 6). Enrichment factors of 34-39 were obtained. Layered double hydroxide-Al 2 O 3 -polymer mixed-matrix disks had an average lifetime of 50 extractions. Analyte recoveries ranged from 93 to 96% for grape juice and nonalcoholic beer samples. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A sensitive and accurate method for the determination of perfluoroalkyl and polyfluoroalkyl substances in human serum using a high performance liquid chromatography-online solid phase extraction-tandem mass spectrometry.

PubMed

Yu, Chang Ho; Patel, Bhupendra; Palencia, Marilou; Fan, Zhihua Tina

2017-01-13

A selective, sensitive, and accurate analytical method for the measurement of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in human serum, utilizing LC-MS/MS (liquid chromatography-tandem mass spectrometry), was developed and validated according to the Centers for Disease Control and Prevention (CDC) guidelines for biological sample analysis. Tests were conducted to determine the optimal analytical column, mobile phase composition and pH, gradient program, and cleaning procedure. The final analytical column selected for analysis was an extra densely bonded silica-packed reverse-phase column (Agilent XDB-C 8 , 3.0×100mm, 3.5μm). Mobile phase A was an aqueous buffer solution containing 10mM ammonium acetate (pH=4.3). Mobile phase B was a mixture of methanol and acetonitrile (1:1, v/v). The gradient program was programmed by initiating a fast elution (%B, from 40 to 65%) between 1.0 and 1.5min, followed by a slow elution (%B: 65-80%) in the period of 1.5-7.5min. The cleanup procedures were augmented by cleaning with (1) various solvents (isopropyl alcohol, methanol, acetonitrile, and reverse osmosis-purified water); (2) extensive washing steps for the autosampler and solid phase extraction (SPE) cartridge; and (3) a post-analysis cleaning step for the whole system. Under the above conditions, the resolution and sensitivity were significantly improved. Twelve target PFASs were baseline-separated (2.5-7.0min) within a 10-min of acquisition time. The limits of detection (LODs) were 0.01ng/mL or lower for all of the target compounds, making this method 5 times more sensitive than previously published methods. The newly developed method was validated in the linear range of 0.01-50ng/mL, and the accuracy (recovery between 80 and 120%) and precision (RSD<20%) were acceptable at three spiked levels (0.25, 2.5, and 25ng/mL). The method development and validation results demonstrated that this method was precise, accurate, and robust, with high-throughput (∼10min per sample); thus suitable for large-scale epidemiological studies. Published by Elsevier B.V.

[Simultaneous determination of sixteen perfluorinated organic compounds in surface water by solid phase extraction and ultra performance liquid chromatography with electrospray ionization tandem mass spectrometry].

PubMed

Zhang, Ming; Tang, Fangliang; Yu, Yayun; Chen, Feng; Xu, Jianfen; Ye, Yonggen

2014-05-01

A high-throughput detection method has been developed for the determination of sixteen perfluorinated organic compounds (PFCs) in surface water by solid phase extraction-ultra performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (SPE-UPLC-ESI-MS/MS). The water samples were concentrated and purified through WAX solid phase extraction cartridges. The UPLC separation was performed on an ACQUITY UPLC BEH C18 column utilizing a gradient elution program of methanol (containing 2 mmol/L ammonium acetate) and water (containing 2 mmol/L ammonium acetate) as the mobile phases at a flow rate of 0.4 mL/min. The MS/MS detection was performed under negative electrospray ionization ( ESI ) in multiple reaction monitoring (MRM) mode. Good linearities were observed in the range of 0.5-100 gg/L or 1.0 - 100 microg/L with correlation coefficients from 0.998 7 to 0.999 9. The limits of detection (LODs) for the sixteen perfluorinated organic compounds were in the range of 0.06-0.46 ng/L. The recoveries ranged from 67.6% to 103% with the relative standard deviations between 2.94% and 12.0%. This method was characterized by high sensitivity and precision, extensive range and high speed, and can be applied for the analysis of PFC contaminants in surface water.

[Determination of wilforine in honey using solid phase extraction purification and ultra performance liquid chromatography-tanden mas spectrometry].

PubMed

Lei, Meikang; Peng, Fang; Ding, Tao; Zhu, Zitong; Xu, Jiawen; Wu, Xiaoqin

2015-01-01

A method based on solid phase extraction and ultra performance liquid chromatography coupled with tandem mass spectrometry (SPE-UPLC-MS/MS) has been proposed for the determination of wilforine residue in honey. After the sample was dissolved with water, concentrated and purified by an HLB solid phase extraction cartridge, the UPLC separation was performed on a Hypersil GOLD C18 column (50 mm x 2.1 mm, 1.9 microm) utilizing a gradient elution program of methanol (containing 0.15% formic acid) and water as mobile phases at a flow rate of 0. 25 mL/min. The determination was carried out with electrospray ion source in the positive mode (ESI) and multiple reaction monitoring (MRM) mode. The mass concentration of wilforine in the range of 0.01-2 microg/L was linearly correlated with the peak area, and the correlation coefficients was greater than 0.998. The limit of quantification (S/N>10) for wilforine was 0.01 microg/kg. The recoveries were 76.1% to 96.2% in the spiked levels of 0.01, 0.05 and 0.5 microg/kg with the relative standard deviations (RSD, n=6) lower than 10%. The results indicate that the method is rapid, sensitive and accurate, and can be applied for the qualitative and quantitative analysis of wilforine in honey.

[Simultaneous determination of nine perfluorinated compound precursors in atmospheric precipitation by solid phase extraction and ultra performance liquid chromatography with tandem mass spectrometry].

PubMed

Zhang, Ming; Tang, Fangliang; Xu, Jianfen; Yu, Bo; Zhang, Wei; Yao, Jianliang; Hu, Minhua

2017-10-08

A high-throughput detection method has been developed for the determination of nine perfluorinated compound precursors (PFCPs) in atmospheric precipitation by solid phase extraction-ultra performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (SPE-UPLC-ESI-MS/MS). The atmospheric precipitation samples were concentrated and purified with HLB solid phase extraction cartridges. The UPLC separation was performed on an HSS T 3 column (100 mm×2.1 mm, 1.7 μm) utilizing a gradient elution program of methanol and water as the mobile phases at a flow rate of 0.2 mL/min. The MS/MS detection was performed under negative electrospray ionization (ESI - ) in multiple reaction monitoring (MRM) mode. Good linearity was observed in the range of 0.05-5.00 μg/L, 0.50-50.0 μg/L or 5.00-500 μg/L with correlation coefficients from 0.9921 to 0.9995. The limits of detection (LODs) for the nine perfluorinated compound precursors were in the ranges of 0.05-7.9 ng/L. The recoveries ranged from 76.0% to 106% with the relative standard deviations between 0.72% and 13.7%. This method is characterized by high sensitivity and precision, extensive analytical range and quick analytical rate, and can be applied for the analysis of perfluorinated compound precursors in atmospheric precipitation.

Validated high-performance liquid chromatographic method utilizing solid-phase extraction for the simultaneous determination of naringenin and hesperetin in human plasma.

PubMed

Kanaze, Feras Imad; Kokkalou, Eugene; Georgarakis, Manolis; Niopas, Ioannis

2004-03-05

Naringenin and hesperetin, the aglycones of the flavanone glucosides naringin and hesperidin occur naturally in citrus fruits. They exert a variety of pharmacological effects such as antioxidant, blood lipid-lowering, anticarcinogenic and inhibit selected cytochrome P-450 enzymes resulting in drug interactions. A specific, sensitive, precise, and accurate solid-phase extraction high-performance liquid chromatographic (HPLC) assay for the simultaneous determination of naringenin and hesperetin in human plasma was developed and validated. After addition of 7-ethoxycoumarin as internal standard, plasma samples were incubated with beta-glucuronidase/sulphatase, and the analytes were isolated from plasma by solid-phase extraction using C(18) cartridges and separated on a C(8) reversed phase column with methanol/water/acetic acid (40:58:2, v/v/v) as the eluent at 45 degrees C. The method was linear in the 10-300 ng/ml concentration range for both naringenin and hesperetin (r>0.999). Recovery for naringenin, hesperetin and internal standard was greater than 76.7%. Intra- and inter-day precision for naringenin ranged from 1.4 to 4.2% and from 1.9 to 5.2%, respectively, and for hesperetin ranged from 1.3 to 4.1% and from 1.7 to 5.1%, respectively. Accuracy was better than 91.5 and 91.3% for naringenin and hesperetin, respectively.

[Determination of deoxynivalenol in grain and its products by solid-phase extraction coupled with high performance liquid chromatography-tandem mass spectrometry].

PubMed

Huang, Juan; Chen, Guosong; Zhang, Xiaoyan; Shen, Chongyu; Lü, Chen; Wu, Bin; Liu, Yan; Chen, Huilan; Ding, Tao

2012-11-01

A method was established for the determination of deoxynivalenol (vomitoxin) in grain and its products based on solid-phase extraction coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The sample was firstly extracted by acetonitrile-water (84:16, v/v). The extract was then cleaned-up by an HLB solid phase extraction cartridge. The separation was carried out on a Phenomenex Kinetex C18 column (100 mm x4. 6 mm, 2.6 microm) with a gradient elution using 0.3% per hundred ammonia solution-acetonitrile as mobile phases. The analysis of deoxynivalenol was performed under electrospray negative ionization mode. The limit of detection (LOD, S/N= 3) and the limit of quantification (LOQ, S/N = 10) were 20 microg/kg and 50 microg/kg, respectively. A good linearity (r > 0.99) was achieved for the target compound over the range of 20-1000 pg/L. The recoveries at the three spiked levels (50, 100, 500 microg/kg) in the blank matrices such as flour, barley, soybean, rice, cornmeal, cassava and wheat, were varied from 75.6% to 111.0% with the relative standard deviations no more than 13. 0%. The method is accurate, efficient, sensitive and practical. The cost of pretreatment is obviously reduced by replacing immunoaffinity columns and Mycosep columns with HLB columns which have the same purification effect.

Solid phase extraction and spectrophotometric determination of Au(III) with 5-(2-hydroxy-5-nitrophenylazo)thiorhodanine.

PubMed

Hu, Qiufen; Chen, Xiubin; Yang, Xiangjun; Huang, Zhangjie; Chen, Jing; Yang, Guangyu

2006-04-01

A new chromogenic reagent, 5-(2-hydroxy-5-nitrophenylazo)thiorhodanine (HNATR) was synthesized. A highly sensitive, selective and rapid method for the determination microg l(-1) level of Au(III) based on the rapid reaction of Au(III) with HNATR and the solid phase extraction of the colored complex with a reversed phase polymer-based C(18) cartridge have been developed. The HNATR reacted with Au(III) to form a red complex of a molar ratio 1:2 (Au(III) to HNATR) in the presence of 0.05 - 0.5 mol l(-1) of phosphoric acid solution and emulsifier-OP medium. This complex was enriched by the solid phase extraction with a polymer-based C(18) cartridge. The enrichment factor of 100 was achieved. The molar absorptivity of the complex is 1.37 x 10(5) l mol(-1) cm(-1) at 520 nm in the measured solution. The system obeys Beer's law in the range of 0.01 - 3 microg ml(-1). The relative standard deviation for eleven replicates sample of 0.5 microg l(-1) level is 2.18%. The detection limit, based on the three times of standard deviation is 0.02 microg l(-1) in the original sample. This method was applied to the determination of gold in water and ore with good results.

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

PubMed

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

2008-03-01

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

Extraction of toxic compounds from saliva by magnetic-stirring-assisted micro-solid-phase extraction step followed by headspace-gas chromatography-ion mobility spectrometry.

PubMed

Criado-García, Laura; Arce, Lourdes

2016-09-01

A new sample extraction procedure based on micro-solid-phase extraction (μSPE) using a mixture of sorbents of different polarities (polymeric reversed-phase sorbent HLB, silica-based sorbent C18, and multiwalled carbon nanotubes) was applied to extract benzene, toluene, butyraldehyde, benzaldehyde, and tolualdehyde present in saliva to avoid interference from moisture and matrix components and enhance sensitivity and selectivity of the ion mobility spectrometry (IMS) methodology proposed. The extraction of target analytes from saliva samples by using μSPE were followed by the desorption step carried out in the headspace vials placed in the autosampler of the IMS device. Then, 200 μL of headspace was injected into the GC column coupled to the IMS for its analysis. The method was fully validated in terms of sensitivity, precision, and recovery. The LODs and LOQs obtained, when analytes were dissolved in saliva samples to consider the matrix effect, were within the range of 0.38-0.49 and 1.26-1.66 μg mL(-1), respectively. The relative standard deviations were <3.5 % for retention time and drift time values, which indicate that the method proposed can be applied to determine toxic compounds in saliva samples. Graphical abstract Summary of steps followed in the experimental set up of this work.

Liquid chromatographic determination of florfenicol in the plasma of multiple species of fish

USGS Publications Warehouse

Vue, C.; Schmidt, L.J.; Stehly, G.R.; Gingerich, W.H.

2002-01-01

A simple method was developed for determining florfenicol concentration in a small volume (250 mul) of plasma from five phylogenetically diverse species of freshwater fish. Florfenicol was isolated from the plasma matrix through C-18 solid-phase extraction and quantified by reversed-phase high-performance liquid chromatography with UV detection. The accuracy (84-104%), precision (%RSDless than or equal to8), and sensitivity (quantitation limit <30 ng/ml) of the method indicate its usefulness for conducting pharmacokinetic studies on a variety of freshwater fish. Published by Elsevier Science B.V.

IN SITU SOLID-PHASE EXTRACTION AND ANALYSIS OF ULTRA-TRACE SYNTHETIC MUSKS IN MUNICIPAL SEWAGE EFFLUENT USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY, FULL-SCAN MODE

EPA Science Inventory

Fragrance materials, such as synthetic musks in aqueous samples, are normally analyzed by GC/MS in the selected ion monitoring (SIM) mode to provide maximum sensitivity after liquid-liquid extraction of 1-L samples. A 1-L sample, however, usually provides too little ana...

ON-SITE SOLID-PHASE EXTRACTION AND LABORATORY ANALYSIS OF ULTRA-TRACE SYNTHETIC MUSKS IN MUNICIPAL SEWAGE EFFLUENT USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY IN THE FULL-SCAN MODE

EPA Science Inventory

Fragrance materials such as synthetic musks in aqueous samples, are normally determined by gas chromatography/mass spectrometry in the selected ion monitoring (SIM) mode to provide maximum sensitivity after liquid-liquid extraction of I -L samples. Full-scan mass spectra are requ...

Rapid quantification of viable Legionella in nuclear cooling tower waters using filter cultivation, fluorescent in situ hybridization and solid-phase cytometry.

PubMed

Baudart, J; Guillaume, C; Mercier, A; Lebaron, P; Binet, M

2015-05-01

To develop a rapid and sensitive method to quantify viable Legionella spp. in cooling tower water samples. A rapid, culture-based method capable of quantifying as few as 600 Legionella microcolonies per litre within 2 days in industrial waters was developed. The method combines a short cultivation step of microcolonies on GVPC agar plate, specific detection of Legionella cells by a fluorescent in situ hybridization (FISH) approach, and a sensitive enumeration using a solid-phase cytometer. Following optimization of the cultivation conditions, the qualitative and quantitative performance of the method was assessed and the method was applied to 262 nuclear power plant cooling water samples. The performance of this method was in accordance with the culture method (NF-T 90-431) for Legionella enumeration. The rapid detection of viable Legionella in water is a major concern to the effective monitoring of this pathogenic bacterium in the main water sources involved in the transmission of legionellosis infection (Legionnaires' disease). The new method proposed here appears to be a robust, efficient and innovative means for rapidly quantifying cultivable Legionella in cooling tower water samples within 48 h. © 2015 The Society for Applied Microbiology.

[Determination of paraquat and diquat in drinking water and environmental water by high performance liquid chromatography coupled with on-line clean-up and solid phase extraction].

PubMed

Chen, Jing; Liu, Zhaojin; An, Baochao; Lu, Yan; Xu, Qun

2012-10-01

An on-line solid phase extraction (SPE) system was used to eliminate the interferences sufficiently and fulfill the simple and sensitive determination of diquat and paraquat in tap and pond water. This on-line SPE system used two SPE cartridges. One was an Acclaim Mixed-Mode WAX-1 cartridge for the elimination of anionic interferences; the other one was an Acclaim Mixed-Mode WCX-1 cartridge for the enrichment of diquat and paraquat and the elimination of co-enriched cationic interferences. The baseline separation of diquat and paraquat was achieved on an Acclaim Trinity P1 column. A dual-gradient high performance liquid chromatographic (HPLC) system provided an efficient platform to fulfill the on-line SPE and separation, and the system operated under automatic control of chromatography data system software. The complete analysis only required 16 min, and the detection limits of the method were 0.12 microg/L for diquat and 0.10 microg/L for paraquat. The method is simple, rapid and sensitive, and can be applied to the determination of diquat and paraquat in drinking water and environmental water.

Solid-phase microextraction coupled to gas chromatography for the determination of 2,3-dimethyl-2,3-dinitrobutane as a marking agent for explosives.

PubMed

Li, Xiujuan; Zeng, Zhaorui; Zeng, Yi

2007-06-15

This paper investigates the detection of 2,3-dimethyl-2,3-dinitrobutane (DMNB), a marking agent in explosives, by gas chromatography (GC) with electron capture detection using solid-phase microextraction (SPME) as a sample preparation technique. The 25,27-dihydroxy-26,28-oxy (2',7'-dioxo-3',6'-diazaoctyl) oxy-p-tert-butylcalix[4]arene/hydroxy-terminated silicone oil coated fiber was highly sensitive to trap DMNB from ammonium nitrate matrix. The analysis was performed by extracting 2g of explosives for 30s at room temperature and then immediately introducing into the heated GC injector for 1min of thermal desorption. The method showed good linearity in the range from 0.01 to 1.0mug/g. The relative standard deviations for these extractions were <8%. The calculated limit of detection for DMNB (S/N=3) was 4.43x10(-4)mug/g, which illustrates that the proposed systems are suitable for explosive detection at trace level. This is the first report of an SPME-GC system shown to extract marking agent in explosives for subsequent detection in a simple, rapid, sensitive, and inexpensive manner.

On-cartridge derivatisation using a calixarene solid-phase extraction sorbent for facile, sensitive and fast determination of formaldehyde in beer.

PubMed

Deng, Zhifen; Hu, Kai; Zhang, Yongming; Zhao, Wenjie; Wang, Fei; Guo, Ling; Zhang, Wenfen; He, Juan; Huang, Yanjie; Zhang, Shusheng

2016-11-15

This work demonstrates the successful application of an on-cartridge derivatisation procedure for facile, fast and sensitive determination of formaldehyde in beer by HPLC-UV. The derivatisation and solid-phase extraction (SPE) were integrated into a novel calixarene SPE sorbent: tetraazacalix[2]arene[2]triazine bonded silica gel. Specifically, 2,4-dinitrophenylhydrazine was adsorbed onto the sorbent in advance, based on the charge-transfer interaction between the macrocyclic molecule and nitrobenzenes. The method was optimised and validated: under the optimal conditions of derivatisation, SPE and HPLC separation, good linearity was obtained in the range of 0.080-3.2μgmL(-1) with a correlation coefficient of 0.9939, the limit of detection was 3.0ngmL(-1) (S/N=3), the limit of quantification was 10ngmL(-1) (S/N=10), and the recovery level using this method was desirable at 75-84%. The developed method was successfully applied to determine formaldehyde content in real beer samples; the results were in the range of 0.11-1.1μgmL(-1). Copyright © 2016. Published by Elsevier Ltd.

Solid phase microextraction and gas chromatography-mass spectrometry methods for residual solvent assessment in seized cocaine and heroin.

PubMed

Cabarcos, Pamela; Herbello-Hermelo, Paloma; Álvarez-Freire, Iván; Moreda-Piñeiro, Antonio; Tabernero, María Jesús; Bermejo, Ana María; Bermejo-Barrera, Pilar

2016-09-01

A simple sample pre-treatment method based on solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) has been optimized and validated for the assessment of 15 residual solvents (2-propanol, 2-methylpentane, 3-methylpentane, acetone, ethyl acetate, benzene, hexane, methylcyclohexane, methylcyclopentane, m-xylene, propyl acetate, toluene, 1,2,4-trimethylbenzene, dichloromethane, and ethylbenzene) in seized illicit cocaine and heroin. DMSO and DMF as sample diluents were found to offer the best residual solvent transference to the head space for further adsorption onto the SPME fiber, and the developed method therefore showed high sensitivity and analytical recovery. Variables affecting SPME were fully evaluated by applying an experimental design approach. Best conditions were found when using an equilibration time of 5 min at 70 °C and headspace sampling of residual solvents at the same temperature for 15 min. Method validation, performed within the requirements of international guidelines, showed excellent sensitivity, as well as intra- and inter-day precision and accuracy. The proposed methodology was applied to 96 cocaine samples and 14 heroin samples seized in Galicia (northwestern Spain) within 2013 and 2014.

Isotope dilution gas chromatography with mass spectrometry for the analysis of 4-octyl phenol, 4-nonylphenol, and bisphenol A in vegetable oils.

PubMed

Wu, Pinggu; Zhang, Liqun; Yang, Dajin; Zhang, Jing; Hu, Zhengyan; Wang, Liyuan; Ma, Bingjie

2016-03-01

By the combination of solid-phase extraction as well as isotope dilution gas chromatography with mass spectrometry, a sensitive and reliable method for the determination of endocrine-disrupting chemicals including bisphenol A, 4-octylphenol, and 4-nonylphenol in vegetable oils was established. The application of a silica/N-(n-propyl)ethylenediamine mixed solid-phase extraction cartridge achieved relatively low matrix effects for bisphenol A, 4-octylphenol, and 4-nonylphenol in vegetable oils. Experiments were designed to evaluate the effects of derivatization, and the extraction parameters were optimized. The estimated limits of detection and quantification for bisphenol A, 4-octylphenol, and 4-nonylphenol were 0.83 and 2.5 μg/kg, respectively. In a spiked experiment in vegetable oils, the recovery of the added bisphenol A was 97.5-110.3%, recovery of the added 4-octylphenol was 64.4-87.4%, and that of 4-nonylphenol was 68.2-89.3%. This sensitive method was then applied to real vegetable oil samples from Zhejiang Province of China, and none of the target compounds were detected. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solid phase extraction of amoxicillin using dibenzo-18-crown-6 modified magnetic-multiwalled carbon nanotubes prior to its spectrophotometric determination.

PubMed

Ahmadi, Mazaher; Madrakian, Tayyebeh; Afkhami, Abbas

2016-01-01

This work reports on a method for selective extraction and sensitive determination of amoxicillin drug (AMX). The method is based on solid phase extraction of AMX by a novel modified magnetic nanoadsorbent prior to spectrophotometric determination of AMX using a procedure based on formation a colored azo-derivative of the investigated drug. The nanoadsorbent has been synthesized by modification of magnetic-multiwalled carbon nanotube with dibenzo-18-crown-6 moieties. The synthesized nanoparticles were characterized using TEM, XRD and FT-IR measurements. At the next step, various factors that could potentially affect adsorption and desorption efficiencies of AMX, have been optimized. The results showed that under the optimized conditions, sensitive and selective determination of the investigated drug in concentration range of 5.0-1000.0 ng mL(-1) with the limit of detection of 3.0 ng mL(-1) was achievable. Furthermore, the real sample analysis (i.e. amoxicillin capsules and human urine samples) results indicated that a reliable promising candidate method has been developed for the determination of AMX in the investigated real samples. Copyright © 2015 Elsevier B.V. All rights reserved.

End-to-end system test for solid-state microdosemeters.

PubMed

Pisacane, V L; Dolecek, Q E; Malak, H; Dicello, J F

2010-08-01

The gold standard in microdosemeters has been the tissue equivalent proportional counter (TEPC) that utilises a gas cavity. An alternative is the solid-state microdosemeter that replaces the gas with a condensed phase (silicon) detector with microscopic sensitive volumes. Calibrations of gas and solid-state microdosemeters are generally carried out using radiation sources built into the detector that impose restrictions on their handling, transportation and licensing in accordance with the regulations from international, national and local nuclear regulatory bodies. Here a novel method is presented for carrying out a calibration and end-to-end system test of a microdosemeter using low-energy photons as the initiating energy source, thus obviating the need for a regulated ionising radiation source. This technique may be utilised to calibrate both a solid-state microdosemeter and, with modification, a TEPC with the higher average ionisation energy of a gas.

Determination of trace iron in the boiler water used in power generation plants by solid-phase spectrophotometry.

PubMed

Sarenqiqige; Maeda, Akihiro; Yoshimura, Kazuhisa

2014-01-01

A sensitive, simple and low-cost determination method for the total iron concentration in boiler water systems of power generation plants was developed by solid phase spectrometry (SPS) using 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPTZ) as a coloring agent. The reagents and 0.08 cm(3) of a cation exchanger were added to a 50-cm(3) boiler water sample, then mixed for 30 min to adsorb/concentrate the produced Fe(TPTZ)2(2+) colored complex on the solid beads, resulting in a 625 times concentration of the target analyte without any other procedure. The detection limit of 0.1 μg dm(-3) was obtained, and the optimum conditions for the digestion procedure and color developing reaction was investigated and reported. According to the application of this method to real samples, the present SPS method is the best one because of the shorter analysis time, simpler operation and use of very low-cost equipment compared to the conventional methods, such as TPTZ solution spectrophotometric method after a 16 times concentration, ICP-MS and AAS.

Determination of solid-liquid partition coefficients (Kd) for the herbicides isoproturon and trifluralin in five UK agricultural soils.

PubMed

Cooke, Cindy M; Shaw, George; Collins, Chris D

2004-12-01

Isoproturon and trifluralin are herbicides of contrasting chemical characters and modes of action. Standard batch sorption procedures were carried out to investigate the individual sorption behaviour of 14C-isoproturon and 14C-trifluralin in five agricultural soils (1.8-4.2% OC), and the soil solid-liquid partition coefficients (Kd values) were determined. Trifluralin exhibited strong partitioning to the soil solid phase (Kd range 106-294) and low desorption potential, thus should not pose a threat to sensitive waters via leaching, although particle erosion and preferential flow pathways may facilitate transport. For isoproturon, soil adsorption was low (Kd range 1.96-5.75) and desorption was high, suggesting a high leaching potential, consistent with isoproturon being the most frequently found pesticide in UK surface waters. Soil partitioning was directly related to soil organic carbon (OC) content. Accumulation isotherms were modelled using a dual-phase adsorption model to estimate adsorption and desorption rate coefficients. Associations between herbicides and soil humic substances were also shown using gel filtration chromatography.

Simultaneous Determination of Parathion, Malathion, Diazinon, and Pirimiphos Methyl in Dried Medicinal Plants Using Solid-Phase Microextraction Fibre Coated with Single-Walled Carbon Nanotubes

PubMed Central

Ahmadkhaniha, Reza; Samadi, Nasrin; Salimi, Mona; Sarkhail, Parisa; Rastkari, Noushin

2012-01-01

A reliable and sensitive headspace solid-phase microextraction gas chromatography-mass spectrometry method for simultaneous determination of different organophosphorus pesticides in dried medicinal plant samples is described. The analytes were extracted by single-walled carbon nanotubes as a new solid-phase microextraction adsorbent. The developed method showed good performance. For diazinon and pirimiphos methyl calibration, curves were linear (r 2 ≥ 0.993) over the concentration ranges from 1.5 to 300 ng g−1, and the limit of detection at signal-to-noise ratio of 3 was 0.3 ng g−1. For parathion and malathion, the linear range and limit of detection were 2.5–300 (r 2 ≥ 0.991) and 0.5 ng g−1, respectively. In addition, a comparative study between the single-walled carbon nanotubes and a commercial polydimethylsiloxane fibre for the determination of target analytes was carried out. Single-walled carbon nanotubes fibre showed higher extraction capacity, better thermal stability (over 350°C), and longer lifespan (over 250 times) than the commercial polydimethylsiloxane fibre. The developed method was successfully applied to determine target organophosphorus pesticides in real samples. PMID:22645439

Thermal decomposition of solid phase nitromethane under various heating rates and target temperatures based on ab initio molecular dynamics simulations.

PubMed

Xu, Kai; Wei, Dong-Qing; Chen, Xiang-Rong; Ji, Guang-Fu

2014-10-01

The Car-Parrinello molecular dynamics simulation was applied to study the thermal decomposition of solid phase nitromethane under gradual heating and fast annealing conditions. In gradual heating simulations, we found that, rather than C-N bond cleavage, intermolecular proton transfer is more likely to be the first reaction in the decomposition process. At high temperature, the first reaction in fast annealing simulation is intermolecular proton transfer leading to CH3NOOH and CH2NO2, whereas the initial chemical event at low temperature tends to be a unimolecular C-N bond cleavage, producing CH3 and NO2 fragments. It is the first time to date that the direct rupture of a C-N bond has been reported as the first reaction in solid phase nitromethane. In addition, the fast annealing simulations on a supercell at different temperatures are conducted to validate the effect of simulation cell size on initial reaction mechanisms. The results are in qualitative agreement with the simulations on a unit cell. By analyzing the time evolution of some molecules, we also found that the time of first water molecule formation is clearly sensitive to heating rates and target temperatures when the first reaction is an intermolecular proton transfer.

Gas chromatographic detection of some nitro explosive compounds in soil samples after solid-phase microextraction with carbon ceramic copper nanoparticle fibers.

PubMed

Farhadi, Khalil; Bochani, Shayesteh; Hatami, Mehdi; Molaei, Rahim; Pirkharrati, Hossein

2014-07-01

In this research, a new solid-phase microextraction fiber based on carbon ceramic composites with copper nanoparticles followed by gas chromatography with flame ionization detection was applied for the extraction and determination of some nitro explosive compounds in soil samples. The proposed method provides an overview of trends related to synthesis of solid-phase microextraction sorbents and their applications in preconcentration and determination of nitro explosives. The sorbents were prepared by mixing of copper nanoparticles with a ceramic composite produced by mixture of methyltrimethoxysilane, graphite, methanol, and hydrochloric acid. The prepared sorbents were coated on copper wires by dip-coating method. The prepared nanocomposites were evaluated statistically and provided better limits of detection than the pure carbon ceramic. The limit of detection of the proposed method was 0.6 μg/g with a linear response over the concentration range of 2-160 μg/g and square of correlation coefficient >0.992. The new proposed fiber has been demonstrated to be a suitable, inexpensive, and sensitive candidate for extraction of nitro explosive compounds in contaminated soil samples. The constructed fiber can be used more than 100 times without the need for surface generation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Application of a novel cold activated carbon fiber-solid phase microextraction for analysis of organochlorine pesticides in soil.

PubMed

Chai, Xiaolan; Jia, Jinping; Sun, Tonghua; Wang, Yalin; Liao, Liyan

2007-08-01

A novel and simple analytical procedure using cold activated carbon fiber-solid phase microextraction (CACF-SPME) was applied to determine organochlorine pesticides (OCs) in soil samples. The pesticides in this study consist of alpha -, beta -, gamma -, and delta -hexachlorocyclohexane (HCH). By heating the sample while cooling the fiber, the developed method not only provides better performance in terms of sensitivity, linearity and recovery but also offers shorter adsorption procedure than that of traditional headspace-solid phase microextraction (HS-SPME). The experimental conditions such as the amount of water, adsorption time and adsorption temperature were optimized. Matrix effects were investigated with different types of soils. We concluded that using the standard addition method was required for quantification purposes. The limits of detection obtained using the proposed method range from 0.01 to 0.05 ng/g, and the recoveries for CACF-SPME are in the range of 80.01% to 89.68% with relative standard deviation (RSDs) better than 8.60%. The proposed method was further applied to determine OCs in real agricultural soil. The results are in good agreement with those obtained using traditional ultrasonic extraction. The research demonstrates the suitability of the CACF-SPME for the analysis of OCs in soil.

Reaction mechanism studies towards effective fabrication of lithium-rich anti-perovskites Li 3OX (X=Cl, Br)

DOE PAGES

Li, Shuai; Zhu, Jinlong; Wang, Yonggang; ...

2015-12-10

Lithium-rich Anti-perovskite (LiRAP), with general formula Li 3OX (X = Cl, Br, I), and recently reported as superionic conductors with 3-dimensional Li + migrating channels, is emerging as a promising candidate for solid electrolyte of all-solid-state LIBs. But, it is still difficult to fabricate pure LiRAP due to the difficulty of the phase formation and moisture-sensitive nature of the products. In this work, we thoroughly studied the formation mechanism of Li 3OCl and Li 3OBr in various solid state reaction routes. We developed different experimental strategies in order to improve the syntheses, in purposes of improved phase stability and large-scalemore » production of LiRAP. One feasible method is to use strongly reductive agents Li metal or LiH to eliminate OH species. The results show that LiH is more effective than Li metal because of negatively charged H - and uniform reaction. The other well-established method is using Li 2O and LiX mixture as reagents to preventing OH phase at the beginning, and using protected ball milling to make fine powders and hence active the reaction. Finally, IR spectroscopy, thermal analyses and first-principle calculation were performed to give indications on the reaction pathway.« less

Molecularly imprinted solid-phase extraction combined with electrochemical oxidation fluorimetry for the determination of methotrexate in human serum and urine

NASA Astrophysics Data System (ADS)

Chen, Suming; Zhang, Zhujun

2008-06-01

The method of synthesis and evaluation of molecularly imprinted polymers was reported. As a selective solid-phase extraction sorbent, the polymers were coupled with electrochemical fluorimetry detection for the efficient determination of methotrexate in serum and urine. Methotrexate was preconcentrated in the molecularly imprinted solid-phase extraction microcolumn packed with molecularly imprinted polymers, and then eluted. The eluate was detected by fluorescence spectrophotometer after electrochemical oxidation. The conditions of preconcentration, elution, electrochemical oxidation and determination were carefully studied. Under the selected experimental conditions, the calibration graph of the fluorescence intensity versus methotrexate concentration was linear from 4 × 10 -9 g mL -1 to 5 × 10 -7 g mL -1, and the detection limit was 8.2 × 10 -10 g mL -1 (3 σ). The relative standard deviation was 3.92% ( n = 7) for 1 × 10 -7 g mL -1 methotrexate. The experiments showed that the selectivity and sensitivity of fluorimetry could be greatly improved by the proposed method. This method has been successfully applied to the determination of methotrexate. At the same time, the binding characteristics of the polymers to the methotrexate were evaluated by batch and dynamic methods.

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

Preston, Daniel N; Peterson, Paul D; Kien - Yin, Lee

Structural damage in energetic materials plays a significant role in the probability of nonshock initiation events. Damage may occur in the form of voids or cracks either within crystals or in binder-rich regions between crystals. These cracks affect whether hotspots generated by impact will quench or propagate under non-shock insult. For this study, we have separately engineered intracrystalline and inter-crystalline cracks in to the HMX-based PBX 9501. Intra-crystalline cracks were created by subjecting HMX to forward and reverse solid-to-solid phase transformations prior to formulation. Inter-crystalline cracks were induced by compressing formulated samples of PBX 9501 at an average strain ratemore » of 0.00285 S{sup -1}. Both sets of pre-damaged explosives were then impact tested using the LANL Type 12 Drop Weight-Impact Machine and their sensitivities compared to nondamaged PBX 9501. Results of these tests clearly show significant differences in sensitivity between damaged and non-damaged PBX 9501.« less

A whole-cell bioreporter assay for quantitative genotoxicity evaluation of environmental samples.

PubMed

Jiang, Bo; Li, Guanghe; Xing, Yi; Zhang, Dayi; Jia, Jianli; Cui, Zhisong; Luan, Xiao; Tang, Hui

2017-10-01

Whole-cell bioreporters have emerged as promising tools for genotoxicity evaluation, due to their rapidity, cost-effectiveness, sensitivity and selectivity. In this study, a method for detecting genotoxicity in environmental samples was developed using the bioluminescent whole-cell bioreporter Escherichia coli recA::luxCDABE. To further test its performance in a real world scenario, the E. coli bioreporter was applied in two cases: i) soil samples collected from chromium(VI) contaminated sites; ii) crude oil contaminated seawater collected after the Jiaozhou Bay oil spill which occurred in 2013. The chromium(VI) contaminated soils were pretreated by water extraction, and directly exposed to the bioreporter in two phases: aqueous soil extraction (water phase) and soil supernatant (solid phase). The results indicated that both extractable and soil particle fixed chromium(VI) were bioavailable to the bioreporter, and the solid-phase contact bioreporter assay provided a more precise evaluation of soil genotoxicity. For crude oil contaminated seawater, the response of the bioreporter clearly illustrated the spatial and time change in genotoxicity surrounding the spill site, suggesting that the crude oil degradation process decreased the genotoxic risk to ecosystem. In addition, the performance of the bioreporter was simulated by a modified cross-regulation gene expression model, which quantitatively described the DNA damage response of the E. coli bioreporter. Accordingly, the bioluminescent response of the bioreporter was calculated as the mitomycin C equivalent, enabling quantitative comparison of genotoxicities between different environmental samples. This bioreporter assay provides a rapid and sensitive screening tool for direct genotoxicity assessment of environmental samples. Copyright © 2017. Published by Elsevier Ltd.

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

Harris, J.M.

Chemical phenomena occurring at boundaries between insulating solids and liquids (adsorption, partition, monolayer self-assembly, catalysis, and chemical reactions) are important to energy-related analytical chemistry. These phenomena are central to chromatography, solid-phase extraction, immobilized analytical reagents, and optical sensors. Chemical interactions in these processes cannot generally be identified solely by equilibrium surface concentrations, since the steady-state behavior does not reveal the mechanism or rates of surface reactions. Goal therefore is to develop surface-sensitive spectroscopies by which chemical kinetics at liquid/solid interfaces can be observed on time-scales from nanoseconds to seconds. In the first year, we have used Joule-discharge heating kinetics tomore » study pore structure of silica gels; effects of pore diameter, particle size, and chemical modification on pore connectivity were investigated. Temperature-jump relaxation measurements of sorption/desorption kinetics at liquid/solid interfaces were also carried out using Joule heating; kinetic barriers to sorption of ions from solution were found for both C18 and Cl surfaces. Through a collaboration with Fritz-Haber Institute in Berlin, we were able to acquire laser temperature-jump data on kinetics at liquid/solid interfaces using a colloidal sample. We also quantified the rate of migration of covalently attached ligands on silica surfaces; from the temperature dependence, the large energy barrier to migration was estimated. A review of applications of electronic spectroscopy (absorption and fluorescence) to reversed-phase chromatographic interfaces was published.« less

[Possibility of the species identification using blood stains located on the material evidences and bone fragments with the method of solid phase enzyme immunoassay with "IgG general-EIA-BEST" kit and human immunoglobulin G].

PubMed

Sidorov, V L; Shvetsova, I V; Isakova, I V

2007-01-01

The authors give the comparative analysis of Russian and foreign forensic medical methods of species character identification of the blood from the stains on the material evidences and bone fragments. It is shown that for this purpose it is feasible to apply human immunoglobulin G (IgG) and solid phase enzyme immunoassay (EIA) with the kit "IgG general-EIA-BEST". In comparison with the methods used in Russia this method is more sensitive, convenient for objective registration and computer processing. The results of experiments shown that it is possible to use the kit "IgG general-EIA-BEST" in forensic medicine for the species character identification of the blood from the stains on the material evidences and bone fragments.

Determination of acrylamide in brewed coffee and coffee powder using polymeric ionic liquid-based sorbent coatings in solid-phase microextraction coupled to gas chromatography-mass spectrometry.

PubMed

Cagliero, Cecilia; Ho, Tien D; Zhang, Cheng; Bicchi, Carlo; Anderson, Jared L

2016-06-03

This study describes a simple and rapid sampling method employing a polymeric ionic liquid (PIL) sorbent coating in direct immersion solid-phase microextraction (SPME) for the trace-level analysis of acrylamide in brewed coffee and coffee powder. The crosslinked PIL sorbent coating demonstrated superior sensitivity in the extraction of acrylamide compared to all commercially available SPME coatings. A spin coating method was developed to evenly distribute the PIL coating on the SPME support and reproducibly produce fibers with a large film thickness. Ninhydrin was employed as a quenching reagent during extraction to inhibit the production of interfering acrylamide. The PIL fiber produced a limit of quantitation for acrylamide of 10μgL(-1) and achieved comparable results to the ISO method in the analysis of six coffee powder samples. Copyright © 2016 Elsevier B.V. All rights reserved.

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

PubMed

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

2003-05-02

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

Solid phase microextraction applied to the analysis of organophosphorus insecticides in fruits.

PubMed

Fytianos, K; Raikos, N; Theodoridis, G; Velinova, Z; Tsoukali, H

2006-12-01

Trace amounts of organophosphorus pesticides (OPs) were determined in various fruits by headspace solid phase microextraction (HS-SPME) and gas chromatography-nitrogen phosphorous detection (GC-NPD). Sampling from the headspace enhanced method selectivity, whereas at the same time improved fiber life time and method sensitivity. Diazinon, parathion, methyl parathion, malathion and fenithrothion were determined in various fruits: more than 150 samples of 21 types of fruits were studied. SPME-GC-NPD provided a useful and very efficient analytical tool: method linearity ranged from 1.2 to 700 ng/ml. Limits of detection (LODs) and quantitation (LOQs) ranged from 0.03 to 3 ng/ml and 0.12 to 10 ng/ml respectively, values well below the residue limits set by the EU. Less than 2% of the samples were found positive containing amounts higher than the EU limits. The effect of fruit peeling and washing was also investigated.

Determination of cocaine, benzoylecgonine and cocaethylene in human hair by solid-phase microextraction and gas chromatography-mass spectrometry.

PubMed

de Toledo, Fernanda Crossi Pereira; Yonamine, Mauricio; de Moraes Moreau, Regina Lucia; Silva, Ovandir Alves

2003-12-25

The present work describes a highly precise and sensitive method developed to detect cocaine (COC), benzoylecgonine (BE, its main metabolite) and cocaethylene (CE, transesterification product of the coingestion of COC with ethanol) in human head hair samples. The method was based on an alkylchloroformate derivatization of benzoylecgonine and the extraction of the analytes by solid-phase microextraction (SPME). Gas chromatography-mass spectrometry (GC-MS) was used to identify and quantify the analytes in selected ion monitoring mode (SIM). The limits of quantification and detection (LOQ and LOD) were: 0.1 ng/mg for COC and CE, and 0.5 ng/mg for BE. Good inter- and intra-assay precision was observed. The dynamic range of the assay was 0.1-50 ng/mg. The method is not time consuming and was shown to be easy to perform.

Coherent diffractive imaging of solid state reactions in zinc oxide crystals

NASA Astrophysics Data System (ADS)

Leake, Steven J.; Harder, Ross; Robinson, Ian K.

2011-11-01

We investigated the doping of zinc oxide (ZnO) microcrystals with iron and nickel via in situ coherent x-ray diffractive imaging (CXDI) in vacuum. Evaporated thin metal films were deposited onto the ZnO microcrystals. A single crystal was selected and tracked through annealing cycles. A solid state reaction was observed in both iron and nickel experiments using CXDI. A combination of the shrink wrap and guided hybrid-input-output phasing methods were applied to retrieve the electron density. The resolution was 33 nm (half order) determined via the phase retrieval transfer function. The resulting images are nevertheless sensitive to sub-angstrom displacements. The exterior of the microcrystal was found to degrade dramatically. The annealing of ZnO microcrystals coated with metal thin films proved an unsuitable doping method. In addition the observed defect structure of one crystal was attributed to the presence of an array of defects and was found to change upon annealing.

Determination of trace quaternary ammonium surfactants in water by combining solid-phase extraction with surface-assisted laser desorption/ionization mass spectrometry.

PubMed

Chen, Y C; Sun, M C

2001-01-01

This study demonstrates the feasibility of combining solid-phase extraction (SPE) with surface-assisted laser desorption/ionization (SALDI) mass spectrometry to determine trace quaternary ammonium surfactants in water. The trace surfactants in water were directly concentrated on the surface of activated carbon sorbent in SPE. The activated carbon sorbent was then mixed with the SALDI liquid for SALDI analysis. No SPE elution procedure was necessary. Experimental results indicate that the surfactants with longer chain alkyl groups exhibit higher sensitivities than those with shorter chain alkyl groups in SPE-SALDI analysis. The detection limit for hexadecyltrimethylammonium bromide is around 10 ppt in SPE-SALDI analysis by sampling 100 mL of aqueous solution, while that of tetradecyltrimethylammonium bromide is about 100 ppt. The detection limit for decyltrimethylammonium bromide and dodecyltrimethylammonium bromide is in the low-ppb range. Copyright 2001 John Wiley & Sons, Ltd.

Determination of azoxystrobin and chlorothalonil using a methacrylate-based polymer modified with gold nanoparticles as solid-phase extraction sorbent.

PubMed

Catalá-Icardo, Mónica; Gómez-Benito, Carmen; Simó-Alfonso, Ernesto Francisco; Herrero-Martínez, José Manuel

2017-01-01

This paper describes a novel and sensitive method for extraction, preconcentration, and determination of two important widely used fungicides, azoxystrobin, and chlorothalonil. The developed methodology is based on solid-phase extraction (SPE) using a polymeric material functionalized with gold nanoparticles (AuNPs) as sorbent followed by high-performance liquid chromatography (HPLC) with diode array detector (DAD). Several experimental variables that affect the extraction efficiency such as the eluent volume, sample flow rate, and salt addition were optimized. Under the optimal conditions, the sorbent provided satisfactory enrichment efficiency for both fungicides, high selectivity and excellent reusability (>120 re-uses). The proposed method allowed the detection of 0.05 μg L -1 of the fungicides and gave satisfactory recoveries (75-95 %) when it was applied to drinking and environmental water samples (river, well, tap, irrigation, spring, and sea waters).

Vibrational Action Spectroscopy of Solids: New Surface-Sensitive Technique

NASA Astrophysics Data System (ADS)

Wu, Zongfang; Płucienik, Agata; Feiten, Felix E.; Naschitzki, Matthias; Wachsmann, Walter; Gewinner, Sandy; Schöllkopf, Wieland; Staemmler, Volker; Kuhlenbeck, Helmut; Freund, Hans-Joachim

2017-09-01

Vibrational action spectroscopy employing infrared radiation from a free-electron laser has been successfully used for many years to study the vibrational and structural properties of gas phase aggregates. Despite the high sensitivity of this method no relevant studies have yet been conducted for solid sample surfaces. We have set up an experiment for the application of this method to such targets, using infrared light from the free-electron laser of the Fritz Haber Institute. In this Letter, we present first results of this technique with adsorbed argon and neon atoms as messengers. We were able to detect surface-located vibrations of a thin V2O3(0 0 0 1 ) film on Au(111) as well as adsorbate vibrations, demonstrating that this method is highly surface sensitive. We consider that the dominant channel for desorption of the messenger atoms is direct inharmonic vibrational coupling, which is essentially insensitive to subsurface or bulk vibrations. Another channel is thermal desorption due to sample heating by absorption of infrared light. The high surface sensitivity of the nonthermal channel and its insensitivity to subsurface modes makes this technique an ideal tool for the study of surface-located vibrations.

Vibrational Action Spectroscopy of Solids: New Surface-Sensitive Technique.

PubMed

Wu, Zongfang; Płucienik, Agata; Feiten, Felix E; Naschitzki, Matthias; Wachsmann, Walter; Gewinner, Sandy; Schöllkopf, Wieland; Staemmler, Volker; Kuhlenbeck, Helmut; Freund, Hans-Joachim

2017-09-29

Vibrational action spectroscopy employing infrared radiation from a free-electron laser has been successfully used for many years to study the vibrational and structural properties of gas phase aggregates. Despite the high sensitivity of this method no relevant studies have yet been conducted for solid sample surfaces. We have set up an experiment for the application of this method to such targets, using infrared light from the free-electron laser of the Fritz Haber Institute. In this Letter, we present first results of this technique with adsorbed argon and neon atoms as messengers. We were able to detect surface-located vibrations of a thin V_{2}O_{3}(0001) film on Au(111) as well as adsorbate vibrations, demonstrating that this method is highly surface sensitive. We consider that the dominant channel for desorption of the messenger atoms is direct inharmonic vibrational coupling, which is essentially insensitive to subsurface or bulk vibrations. Another channel is thermal desorption due to sample heating by absorption of infrared light. The high surface sensitivity of the nonthermal channel and its insensitivity to subsurface modes makes this technique an ideal tool for the study of surface-located vibrations.

Modified sedimentation-dispersion model for solids in a three-phase slurry column

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

Smith, D.N.; Ruether, J.A.; Shah, Y.T.

1986-03-01

Solids distribution data for a three-phase, batch-fluidized slurry bubble column (SBC) are presented, using air as the gas phase, pure liquids and solutions as the liquid phase, and glass beads and carborundum catalyst powder as the solid phase. Solids distribution data for the three-phase SBC operated in a continuous mode of operation are also presented, using nitrogen as the gas phase, water as the liquid phase, and glass beads as the solid phase. A new model to provide a reasonable approach to predict solids concentration distributions for systems containing polydispersed solids is presented. The model is a modification of standardmore » sedimentation-dispersion model published earlier. Empirical correlations for prediction of hindered settling velocity and solids dispersion coefficient for systems containing polydispersed solids are presented. A new method of evaluating critical gas velocity (CGV) from concentrations of the sample withdrawn at the same port of the SBC is presented. Also presented is a new mapping for CGV which separates the two regimes in the SBC, namely, incomplete fluidization and complete fluidization.« less

Using the Space-Borne NASA Scatterometer (NSCAT) to Determine The Frozen and Thawed Seasons of a Boreal Landscape

NASA Technical Reports Server (NTRS)

Frolking, S.; McDonald, K. C.; Kimball, J. S.; Way, J. B.; Zimmermann, R.; Running, S. W.

1998-01-01

We hypothesize that the strong sensitivity of radar backscatter to surface dielectric properties, and hence to the phase (solid or liquid) of any water near the surface, should make space-borne radar observations a powerful tool for large-scale spatial monitoring of the freeze/thaw state of the land surface, and thus ecosystem growing season length.

How to distinguish various components of the SHG signal recorded from the solid/liquid interface?

NASA Astrophysics Data System (ADS)

Gassin, Pierre-Marie; Martin-Gassin, Gaelle; Prelot, Benedicte; Zajac, Jerzy

2016-11-01

Second harmonic generation (SHG) may be an important tool to probe buried solid/liquid interfaces because of its inherent surface sensitivity. A detailed interpretation of dye adsorption onto Si-SiO2 wafer is not straightforward because both adsorbent and adsorbate contribute to the overall SHG signal. The polarization resolved SHG analysis points out that the adsorbent and adsorbate contributions are out of phase by π/2 in the present system. The surface nonlinear susceptibility χ(2) represents thus a complex tensor in which its real part is related to the adsorbent contribution and its imaginary part to the adsorbate one.

A novel DNA/histone H4 peptide complex detects autoantibodies in systemic lupus erythematosus sera.

PubMed

Panza, Filomena; Alcaro, Maria Claudia; Petrelli, Fiorella; Angelotti, Francesca; Pratesi, Federico; Rovero, Paolo; Migliorini, Paola

2016-10-04

The detection of anti-dsDNA antibodies is critical for the diagnosis and follow-up of systemic lupus erythematosus (SLE) patients. The presently available assays are characterized by a non-optimal specificity (solid phase assays) or sensitivity (Crithidia Luciliae immunofluorescence test (CLIFT)). To overcome the limits of CLIFT and solid phase chromatin assays, we explored the diagnostic potential of an assay based on plasmid DNA containing a highly bent fragment of 211 bp from Crithidia Luciliae minicircles, complexed with histone peptides. Electrically neutral complexes of PK201/CAT plasmid (PK) DNA and histone 4 (H4) peptides were evaluated by electromobility shift assay. Complexes of H4 peptides and PK were absorbed to the solid phase to detect specific immunoglobulin G (IgG) in sera. Sera from 109 SLE patients, 100 normal healthy subjects, and 169 disease controls were tested. H4(14-34) containing the consensus sequence for DNA binding interacts with PK, retarding its migration. H4(14-34)/PK complexes were used to test sera by ELISA. Anti-H4-PK antibodies were detected in 56 % of SLE sera (more frequently in patients with skin or joint involvement) versus 5.9 % in disease controls; inhibition assays show that sera react with epitopes present on DNA or on the complex, not on the peptide. Antibody titer is correlated with European Consensus Lupus Activity Measurement (ECLAM) score and anti-complement component 1q (C1q) antibodies, negatively with C3 levels. Anti-H4-PK antibodies compared with CLIFT and solid phase dsDNA assays display moderate concordance. The H4/PK assay is a simple and reliable test which is useful for the differential diagnosis and evaluation of disease activity in SLE patients.

A new approach to phosphoserine and phosphothreonine analysis in peptides and proteins: chemical modification, enrichment via solid-phase reversible binding, and analysis by mass spectrometry.

PubMed

Thaler, Florian; Valsasina, Barbara; Baldi, Rosario; Xie, Jin; Stewart, Albert; Isacchi, Antonella; Kalisz, Henryk M; Rusconi, Luisa

2003-06-01

beta-Elimination of the phosphate group on phosphoserine and phosphothreonine residues and addition of an alkyldithiol is a useful tool for analysis of the phosphorylation states of proteins and peptides. We have explored the influence of several conditions on the efficiency of this PO(4)(3-) elimination reaction upon addition of propanedithiol. In addition to the described influence of different bases, the solvent composition was also found to have a major effect on the yield of the reaction. In particular, an increase in the percentage of DMSO enhances the conversion rate, whereas a higher amount of protic polar solvents, such as water or isopropanol, induces the opposite effect. We have also developed a protocol for enrichment of the modified peptides, which is based on solid-phase covalent capture/release with a dithiopyridino-resin. The procedure for beta-elimination and isolation of phosphorylated peptides by solid-phase capture/release was developed with commercially available alpha-casein. Enriched peptide fragments were characterized by MALDI-TOF mass spectrometric analysis before and after alkylation with iodoacetamide, which allowed rapid confirmation of the purposely introduced thiol moiety. Sensitivity studies, carried out in order to determine the detection limit, demonstrated that samples could be detected even in the low picomolar range by mass spectrometry. The developed solid-phase enrichment procedure based on reversible covalent binding of the modified peptides is more effective and significantly simpler than methods based on the interaction between biotin and avidin, which require additional steps such as tagging the modified peptides and work-up of the samples prior to the affinity capture step.

Magnetic-field sensing with quantum error detection under the effect of energy relaxation

NASA Astrophysics Data System (ADS)

Matsuzaki, Yuichiro; Benjamin, Simon

2017-03-01

A solid state spin is an attractive system with which to realize an ultrasensitive magnetic field sensor. A spin superposition state will acquire a phase induced by the target field, and we can estimate the field strength from this phase. Recent studies have aimed at improving sensitivity through the use of quantum error correction (QEC) to detect and correct any bit-flip errors that may occur during the sensing period. Here we investigate the performance of a two-qubit sensor employing QEC and under the effect of energy relaxation. Surprisingly, we find that the standard QEC technique to detect and recover from an error does not improve the sensitivity compared with the single-qubit sensors. This is a consequence of the fact that the energy relaxation induces both a phase-flip and a bit-flip noise where the former noise cannot be distinguished from the relative phase induced from the target fields. However, we have found that we can improve the sensitivity if we adopt postselection to discard the state when error is detected. Even when quantum error detection is moderately noisy, and allowing for the cost of the postselection technique, we find that this two-qubit system shows an advantage in sensing over a single qubit in the same conditions.

Characterization of Pharmaceutical Cocrystals and Salts by Dynamic Nuclear Polarization-Enhanced Solid-State NMR Spectroscopy

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

Zhao, Li; Hanrahan, Michael P.; Chakravarty, Paroma

Multicomponent solids such as cocrystals have emerged as a way to control and engineer the stability, solubility and manufacturability of solid active pharmaceutical ingredients (APIs). Cocrystals are typically formed by solution- or solid-phase reactions of APIs with suitable cocrystal coformers, which are often weak acids. One key structural question about a given multicomponent solid is whether it should be classified as a salt, where the basic API is protonated by the acid, or as a cocrystal, where the API and coformer remain neutral and engage in hydrogen bonding interactions. It has previously been demonstrated that solid-state NMR spectroscopy is amore » powerful probe of structure in cocrystals and salts of APIs, however, the poor sensitivity of solid-state NMR spectroscopy usually restricts the types of experiments that can be performed. Here relayed dynamic nuclear polarization (DNP) was applied to reduce solid-state NMR experiments by one to two orders of magnitude for salts and cocrystals of a complex API. The large sensitivity gains from DNP facilitates rapid acquisition of natural isotopic abundance 13C and 15N solid-state NMR spectra. Critically, DNP enables double resonance 1H-15N solid-state NMR experiments such as 2D 1H-15N HETCOR, 1H-15N CP-build up, 15N{1H} J-resolved/attached proton tests, 1H-15N DIPSHIFT and 1H-15N PRESTO. The latter two experiments allow 1H-15N dipolar coupling constants and H-N bond lengths to be accurately measured, providing an unambiguous assignment of nitrogen protonation state and definitive classification of the multi-component solids as cocrystals or salts. In conclusion, these types of measurements should also be extremely useful in the context of polymorph discrimination, NMR crystallography structure determination and for probing hydrogen bonding in a variety of organic materials.« less

Characterization of Pharmaceutical Cocrystals and Salts by Dynamic Nuclear Polarization-Enhanced Solid-State NMR Spectroscopy

DOE PAGES

Zhao, Li; Hanrahan, Michael P.; Chakravarty, Paroma; ...

2018-02-15

Multicomponent solids such as cocrystals have emerged as a way to control and engineer the stability, solubility and manufacturability of solid active pharmaceutical ingredients (APIs). Cocrystals are typically formed by solution- or solid-phase reactions of APIs with suitable cocrystal coformers, which are often weak acids. One key structural question about a given multicomponent solid is whether it should be classified as a salt, where the basic API is protonated by the acid, or as a cocrystal, where the API and coformer remain neutral and engage in hydrogen bonding interactions. It has previously been demonstrated that solid-state NMR spectroscopy is amore » powerful probe of structure in cocrystals and salts of APIs, however, the poor sensitivity of solid-state NMR spectroscopy usually restricts the types of experiments that can be performed. Here relayed dynamic nuclear polarization (DNP) was applied to reduce solid-state NMR experiments by one to two orders of magnitude for salts and cocrystals of a complex API. The large sensitivity gains from DNP facilitates rapid acquisition of natural isotopic abundance 13C and 15N solid-state NMR spectra. Critically, DNP enables double resonance 1H-15N solid-state NMR experiments such as 2D 1H-15N HETCOR, 1H-15N CP-build up, 15N{1H} J-resolved/attached proton tests, 1H-15N DIPSHIFT and 1H-15N PRESTO. The latter two experiments allow 1H-15N dipolar coupling constants and H-N bond lengths to be accurately measured, providing an unambiguous assignment of nitrogen protonation state and definitive classification of the multi-component solids as cocrystals or salts. In conclusion, these types of measurements should also be extremely useful in the context of polymorph discrimination, NMR crystallography structure determination and for probing hydrogen bonding in a variety of organic materials.« less

Liquid chromatographic determination of benzocaine and N-acetylbenzocaine in the edible fillet tissue from rainbow trout

USGS Publications Warehouse

Meinertz, J.R.; Stehly, G.R.; Hubert, T.D.; Bernardy, J.A.

1999-01-01

A method was developed for determining benzocaine and N-acetylbenzocaine concentrations in fillet tissue of rainbow trout. The method involves extracting the analytes with acetonitrile, removing lipids or hydrophobic compounds from the extract with hexane, and providing additional clean-up with solid-phase extraction techniques. Analyte concentrations are determined using reversed-phase high-performance liquid chromatographic techniques with an isocratic mobile phase and UV detection. The accuracy (range, 92 to 121%), precision (R.S.D., <14%), and sensitivity (method quantitation limit, <24 ng/g) for each analyte indicate the usefulness of this method for studies characterizing the depletion of benzocaine residues from fish exposed to benzocaine. Copyright (C) 1999.

Universality away from critical points in a thermostatistical model

NASA Astrophysics Data System (ADS)

Lapilli, C. M.; Wexler, C.; Pfeifer, P.

Nature uses phase transitions as powerful regulators of processes ranging from climate to the alteration of phase behavior of cell membranes to protect cells from cold, building on the fact that thermodynamic properties of a solid, liquid, or gas are sensitive fingerprints of intermolecular interactions. The only known exceptions from this sensitivity are critical points. At a critical point, two phases become indistinguishable and thermodynamic properties exhibit universal behavior: systems with widely different intermolecular interactions behave identically. Here we report a major counterexample. We show that different members of a family of two-dimensional systems —the discrete p-state clock model— with different Hamiltonians describing different microscopic interactions between molecules or spins, may exhibit identical thermodynamic behavior over a wide range of temperatures. The results generate a comprehensive map of the phase diagram of the model and, by virtue of the discrete rotors behaving like continuous rotors, an emergent symmetry, not present in the Hamiltonian. This symmetry, or many-to-one map of intermolecular interactions onto thermodynamic states, demonstrates previously unknown limits for macroscopic distinguishability of different microscopic interactions.

Different Results of IgE Binding- and Crosslinking-Based Allergy Tests Caused by Allergen Immobilization.

PubMed

Okamoto-Uchida, Yoshimi; Nakamura, Ryosuke; Matsuzawa, Yumiko; Soma, Megumi; Kawakami, Hiroshi; Ishii-Watabe, Akiko; Nishimaki-Mogami, Tomoko; Teshima, Reiko; Saito, Yoshiro

2016-01-01

The physicochemical nature of allergen molecules differ from the liquid phase to the solid phase. However, conventional allergy tests are based on the detection of immunoglobulin (Ig)E binding to immobilized allergens. We recently developed an in vitro allergy testing method using a luciferase-reporting humanized rat mast cell line to detect IgE crosslinking-induced luciferase expression (EXiLE test). The aim of the present study was to evaluate the effects of antigen immobilization on the results of different in vitro allergy tests using two anti-ovalbumin (OVA) antibodies (Abs), E-C1 and E-G5, with different properties in the OVA-induced allergic reaction. Both Abs showed clear binding to OVA with an enzyme-linked immunosorbent assay and by BIAcore analysis. However, only E-C1 potentiated EXiLE response for the liquid-phase OVA. On the other hand, OVA immobilized on solid-phase induced EXiLE responses in both E-C1 Ab- and E-G5 Ab-sensitized mast cells. Western blotting of OVA indicated that E-C1 Ab binds both to OVA monomers and dimers, unlike E-G5 Ab, which probably binds only to the OVA dimer. These results suggest that antigen immobilization enhanced IgE crosslinking ability through multimerization of allergen molecules in the solid phase, resulting in an increase in false positives in IgE binding-based conventional in vitro allergy tests. These findings shed light on the physicochemical nature of antigens as an important factor for the development and evaluation of in vitro allergy tests and suggest that mast cell activation-based allergy testing with liquid-phase allergens is a promising strategy to evaluate the physiological interactions of IgE and allergens.

Miscibility and Phase Behavior of N-Acylethanolamine/Diacylphosphatidylethanolamine Binary Mixtures of Matched Acyl Chainlengths (n = 14, 16)

PubMed Central

Kamlekar, Ravi Kanth; Satyanarayana, S.; Marsh, Derek; Swamy, Musti J.

2007-01-01

The miscibility and phase behavior of hydrated binary mixtures of two N-acylethanolamines (NAEs), N-myristoylethanolamine (NMEA), and N-palmitoylethanolamine (NPEA), with the corresponding diacyl phosphatidylethanolamines (PEs), dimyristoylphosphatidylethanolamine (DMPE), and dipalmitoylphosphatidylethanolamine (DPPE), respectively, have been investigated by differential scanning calorimetry (DSC), spin-label electron spin resonance (ESR), and 31P-NMR spectroscopy. Temperature-composition phase diagrams for both NMEA/DMPE and NPEA/DPPE binary systems were established from high sensitivity DSC. The structures of the phases involved were determined by 31P-NMR spectroscopy. For both systems, complete miscibility in the fluid and gel phases is indicated by DSC and ESR, up to 35 mol % of NMEA in DMPE and 40 mol % of NPEA in DPPE. At higher contents of the NAEs, extensive solid-fluid phase separation and solid-solid immiscibility occur depending on the temperature. Characterization of the structures of the mixtures formed with 31P-NMR spectroscopy shows that up to 75 mol % of NAE, both DMPE and DPPE form lamellar structures in the gel phase as well as up to at least 65°C in the fluid phase. ESR spectra of phosphatidylcholine spin labeled at the C-5 position in the sn-2 acyl chain present at a probe concentration of 1 mol % exhibit strong spin-spin broadening in the low-temperature region for both systems, suggesting that the acyl chains pack very tightly and exclude the spin label. However, spectra recorded in the fluid phase do not exhibit any spin-spin broadening and indicate complete miscibility of the two components. The miscibility of NAE and diacyl PE of matched chainlengths is significantly less than that found earlier for NPEA and dipalmitoylphosphatidylcholine, an observation that is consistent with the notion that the NAEs are most likely stored as their precursor lipids (N-acyl PEs) and are generated only when the system is subjected to membrane stress. PMID:17369415

A phase 1 dose-escalation study of the oral histone deacetylase inhibitor abexinostat in combination with standard hypofractionated radiotherapy in advanced solid tumors

PubMed Central

Deutsch, Eric; Moyal, Elizabeth Cohen-Jonathan; Gregorc, Vanesa; Zucali, Paolo Andrea; Menard, Jean; Soria, Jean-Charles; Kloos, Ioana; Hsu, Jeff; Luan, Ying; Liu, Emily; Vezan, Remus; Graef, Thorsten; Rivera, Sofia

2017-01-01

Current treatments for advanced solid tumors tend to be only palliative. Although radiotherapy is administered with a curative intent, radioresistance and dose-limiting toxicities pose limitations to treatment. Abexinostat, an oral pan-histone deacetylase inhibitor, demonstrated enhanced sensitivity to radiation in various solid tumor cell lines. We conducted an exploratory, phase 1, dose-escalation study of abexinostat in combination with standard hypofractionated radiotherapy in patients with advanced solid tumors treated in a palliative setting. Among 58 treated patients, the median age was 61.5 years (range, 20-82); 47% of the patients had M1 stage disease, and 95% had received previous chemotherapy alone or chemotherapy in combination with surgery and/or radiotherapy. The recommended phase 2 dose was determined to be 90 mg/m2 (140 mg). Of the 51 patients evaluable for response, best overall response was 8% (1 complete response [CR], 3 partial responses [PRs]), and best loco-regional response was 12% (1 CR and 5 PRs) at a median follow-up of 16 weeks. Of note, patients with target or non-target brain lesions showed encouraging responses, with 1 patient achieving a best loco-regional response of CR. Treatment-emergent grade ≥3 adverse events (AEs) were few, with most common being thrombocytopenia (17%), lymphopenia (12%), and hypokalemia (7%). Six patients (10%) discontinued treatment due to AEs. No grade ≥3 prolongation of the QTc interval was observed, with no treatment discontinuations due to this AE. Oral abexinostat combined with radiotherapy was well tolerated in patients with advanced solid tumors. The combination may have potential for treatment of patients with brain lesions. PMID:28915584

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.

Phase behavior of dioleyphosphatidylethanolamine molecules in the presence of components of pH-sensitive liposomes and paclitaxel.

PubMed

Monteiro, Liziane O F; Lopes, Sávia C A; Barros, André Luís B; Magalhães-Paniago, Rogério; Malachias, Ângelo; Oliveira, Mônica C; Leite, Elaine A

2016-08-01

Paclitaxel is a potent antimicrotubule chemotherapeutic agent widely used for clinical treatment of a variety of solid tumors. However, the low solubility of the drug in aqueous medium and the toxic effects of the commercially available formulation, Taxol(®), has hindered its clinical application. To overcome these paclitaxel-related disadvantages, several drug delivery approaches have been thoroughly investigated. In this context, our research group has developed long-circulating and pHsensitive liposomes containing paclitaxel composed of dioleylphosphatidylethanolamine, cholesterylhemisuccinate and distearoylphosphatidylethanolamine-polyethylene glycol2000, which have shown to be very promising carriers for this taxane. For the destabilization of pH-sensitive liposomal systems and the release of the encapsulated drug in the cytoplasm of tumor cells, the occurrence of a phase transition from a lamellar to a non-lamellar phase of dioleylphosphatidylethanolamine molecules is essential. Two techniques, differential scanning calorimetry and small angle X-ray scattering, were used to investigate the influence of the liposomal components and paclitaxel in the phase transition process of dioleylphosphatidylethanolamine molecules and to evaluate the pH-sensitivity of the formulation under low hydration conditions. The findings clearly evidence the phase transition of dioleylphosphatidylethanolamine molecules in the presence and absence of PTX indicating that the introduction of the drug in the system does not bring damage to the pH-sensitivity of the system, which resulting in liposome destabilization at low pH regions and encapsulated paclitaxel release preferentially in a desired target tissue. Copyright © 2016 Elsevier B.V. All rights reserved.

Molecularly imprinted coated graphene oxide solid-phase extraction monolithic capillary column for selective extraction and sensitive determination of phloxine B in coffee bean.

PubMed

Zhai, Haiyun; Su, Zihao; Chen, Zuanguang; Liu, Zhenping; Yuan, Kaisong; Huang, Lu

2015-03-20

A method was developed to sensitively determine phloxine B in coffee bean by molecularly imprinted polymers (MIPs) coated graphene oxide (GO) solid-phase extraction (GO-MISPE) coupled with high-performance liquid chromatography and laser-induced fluorescence detection (HPLC-LIF). The GO-MISPE capillary monolithic column was prepared by water-bath in situ polymerization, using GO as supporting material, phloxine B, methacrylic acid (MAA), and ethylene dimethacrylate (EDMA) as template, functional monomer, and cross-linker, respectively. The properties of the homemade GO-MISPE capillary monolithic column, including capacity and specificity, were investigated under optimized conditions. The GO-MIPs were characterized by scanning electron microscopy (SEM) and Fourier transform-infrared spectroscopy (FT-IR). The mean recoveries of phloxine B in coffee bean ranged from 89.5% to 91.4% and the intra-day and inter-day relative standard deviation (RSD) values all ranged from 3.6% to 4.7%. Good linearity was obtained over 0.001-2.0 μg mL(-1) (r=0.9995) with the detection limit (S/N=3) of 0.075 ng mL(-1). Under the selected conditions, enrichment factors of over 90-fold were obtained and extraction on the monolithic column effectively cleaned up the coffee bean matrix. The results demonstrated that the proposed GO-MISPE HPLC-LIF method can be applied to sensitively determine phloxine B in coffee bean. Copyright © 2015 Elsevier B.V. All rights reserved.

Sample preparation techniques for the determination of trace residues and contaminants in foods.

PubMed

Ridgway, Kathy; Lalljie, Sam P D; Smith, Roger M

2007-06-15

The determination of trace residues and contaminants in complex matrices, such as food, often requires extensive sample extraction and preparation prior to instrumental analysis. Sample preparation is often the bottleneck in analysis and there is a need to minimise the number of steps to reduce both time and sources of error. There is also a move towards more environmentally friendly techniques, which use less solvent and smaller sample sizes. Smaller sample size becomes important when dealing with real life problems, such as consumer complaints and alleged chemical contamination. Optimal sample preparation can reduce analysis time, sources of error, enhance sensitivity and enable unequivocal identification, confirmation and quantification. This review considers all aspects of sample preparation, covering general extraction techniques, such as Soxhlet and pressurised liquid extraction, microextraction techniques such as liquid phase microextraction (LPME) and more selective techniques, such as solid phase extraction (SPE), solid phase microextraction (SPME) and stir bar sorptive extraction (SBSE). The applicability of each technique in food analysis, particularly for the determination of trace organic contaminants in foods is discussed.

Sensitivity of Imaging Materials to Electron Beam Irradiation

DTIC Science & Technology

1991-04-01

solvent/nonsolvent ratio, and in the solid state by applying mechanical stresses. The terms thermochromism , solvatochromism, and mechanochromism have been...these examples, the thermochromic phase transitions that occur in solution are reversible [101. The changes in optical absorption for solutions of 3BCMU...three-dimensional perspective, as would be observed in a monomolecular layer of an LB film. Flanking this view are both a side view (14a) and a front

Solid-phase microextraction method development for headspace analysis of volatile flavor compounds.

PubMed

Roberts, D D; Pollien, P; Milo, C

2000-06-01

Solid-phase microextraction (SPME) fibers were evaluated for their ability to adsorb volatile flavor compounds under various conditions with coffee and aqueous flavored solutions. Experiments comparing different fibers showed that poly(dimethylsiloxane)/divinylbenzene had the highest overall sensitivity. Carboxen/poly(dimethylsiloxane) was the most sensitive to small molecules and acids. As the concentrations of compounds increased, the quantitative linear range was exceeded as shown by competition effects with 2-isobutyl-3-methoxypyrazine at concentrations above 1 ppm. A method based on a short-time sampling of the headspace (1 min) was shown to better represent the equilibrium headspace concentration. Analysis of coffee brew with a 1-min headspace adsorption time was verified to be within the linear range for most compounds and thus appropriate for relative headspace quantification. Absolute quantification of volatiles, using isotope dilution assays (IDA), is not subject to biases caused by excess compound concentrations or complex matrices. The degradation of coffee aroma volatiles during storage was followed by relative headspace measurements and absolute quantifications. Both methods gave similar values for 3-methylbutanal, 4-ethylguaiacol, and 2,3-pentanedione. Acetic acid, however, gave higher values during storage upon relative headspace measurements due to concurrent pH decreases that were not seen with IDA.

Solid-phase microextraction fiber development for sampling and analysis of volatile organohalogen compounds in air.

PubMed

Attari, Seyed Ghavameddin; Bahrami, Abdolrahman; Shahna, Farshid Ghorbani; Heidari, Mahmoud

2014-01-01

A green, environmental friendly and sensitive method for determination of volatile organohalogen compounds was described in this paper. The method is based on a homemade sol-gel single-walled carbon nanotube/silica composite coated solid-phase microextraction to develop for sampling and analysis of Carbon tetrachloride, Benzotrichloride, Chloromethyl methyl ether and Trichloroethylene in air. Application of this method was investigated under different laboratory conditions. Predetermined concentrations of each analytes were prepared in a home-made standard chamber and the influences of experimental parameters such as temperature, humidity, extraction time, storage time, desorption temperature, desorption time and the sorbent performance were investigated. Under optimal conditions, the use of single-walled carbon nanotube/silica composite fiber showed good performance, high sensitive and fast sampling of volatile organohalogen compounds from air. For linearity test the regression correlation coefficient was more than 98% for analyte of interest and linear dynamic range for the proposed fiber and the applied Gas Chromatography-Flame Ionization Detector technique was from 1 to 100 ngmL(-1). Method detection limits ranged between 0.09 to 0.2 ngmL(-1) and method quantification limits were between 0.25 and 0.7 ngmL(-1). Single-walled carbon nanotube/silica composite fiber was highly reproducible, relative standard deviations were between 4.3 to 11.7 percent.

Are metal-organic frameworks able to provide a new generation of solid-phase microextraction coatings? - A review.

PubMed

Rocío-Bautista, Priscilla; Pacheco-Fernández, Idaira; Pasán, Jorge; Pino, Verónica

2016-10-05

Solid-phase microextraction (SPME) is a powerful technique commonly used in sample preparation for extraction/preconcentration of analytes from a wide variety of samples. Among the trends in improving SPME applications, current investigations are focused on the development of novel coatings able to improve the extraction efficiency, sensitivity, and thermal and mechanical stability, within other properties, of current commercial SPME fibers. Metal-organic frameworks (MOFs) merit to be highlighted as promising sorbent materials in SPME schemes. MOFs are porous hybrid materials composed by metal ions and organic linkers, presenting the highest surface areas known, with ease synthesis and high tuneability, together with adequate chemical and thermal stability. For MOF based-SPME fibers, it results important to pretreat adequately the SPME supports to ensure the correct formation of the MOF onto the fiber or the attachment MOF-support. This, in turn, will increase the final stability of the fiber while generating uniform coatings. This review provides a critical overview of the current state of the use of MOFs as SPME coatings, not only highlighting the advantages of these materials versus commercial SPME coatings in terms of stability, selectivity, and sensitivity; but also insightfully describing the current methods to obtain reproducible MOF-based SPME coatings. Copyright © 2016 Elsevier B.V. All rights reserved.

Attosecond transient absorption instrumentation for thin film materials: Phase transitions, heat dissipation, signal stabilization, timing correction, and rapid sample rotation.

PubMed

Jager, Marieke F; Ott, Christian; Kaplan, Christopher J; Kraus, Peter M; Neumark, Daniel M; Leone, Stephen R

2018-01-01

We present an extreme ultraviolet (XUV) transient absorption apparatus tailored to attosecond and femtosecond measurements on bulk solid-state thin-film samples, specifically when the sample dynamics are sensitive to heating effects. The setup combines methodology for stabilizing sub-femtosecond time-resolution measurements over 48 h and techniques for mitigating heat buildup in temperature-dependent samples. Single-point beam stabilization in pump and probe arms and periodic time-zero reference measurements are described for accurate timing and stabilization. A hollow-shaft motor configuration for rapid sample rotation, raster scanning capability, and additional diagnostics are described for heat mitigation. Heat transfer simulations performed using a finite element analysis allow comparison of sample rotation and traditional raster scanning techniques for 100 Hz pulsed laser measurements on vanadium dioxide, a material that undergoes an insulator-to-metal transition at a modest temperature of 340 K. Experimental results are presented confirming that the vanadium dioxide (VO 2 ) sample cannot cool below its phase transition temperature between laser pulses without rapid rotation, in agreement with the simulations. The findings indicate the stringent conditions required to perform rigorous broadband XUV time-resolved absorption measurements on bulk solid-state samples, particularly those with temperature sensitivity, and elucidate a clear methodology to perform them.

Attosecond transient absorption instrumentation for thin film materials: Phase transitions, heat dissipation, signal stabilization, timing correction, and rapid sample rotation

NASA Astrophysics Data System (ADS)

Jager, Marieke F.; Ott, Christian; Kaplan, Christopher J.; Kraus, Peter M.; Neumark, Daniel M.; Leone, Stephen R.

2018-01-01

We present an extreme ultraviolet (XUV) transient absorption apparatus tailored to attosecond and femtosecond measurements on bulk solid-state thin-film samples, specifically when the sample dynamics are sensitive to heating effects. The setup combines methodology for stabilizing sub-femtosecond time-resolution measurements over 48 h and techniques for mitigating heat buildup in temperature-dependent samples. Single-point beam stabilization in pump and probe arms and periodic time-zero reference measurements are described for accurate timing and stabilization. A hollow-shaft motor configuration for rapid sample rotation, raster scanning capability, and additional diagnostics are described for heat mitigation. Heat transfer simulations performed using a finite element analysis allow comparison of sample rotation and traditional raster scanning techniques for 100 Hz pulsed laser measurements on vanadium dioxide, a material that undergoes an insulator-to-metal transition at a modest temperature of 340 K. Experimental results are presented confirming that the vanadium dioxide (VO2) sample cannot cool below its phase transition temperature between laser pulses without rapid rotation, in agreement with the simulations. The findings indicate the stringent conditions required to perform rigorous broadband XUV time-resolved absorption measurements on bulk solid-state samples, particularly those with temperature sensitivity, and elucidate a clear methodology to perform them.

Natural abundance high-resolution solid state 2 H NMR spectroscopy

NASA Astrophysics Data System (ADS)

Aliev, Abil E.; Harris, Kenneth D. M.; Apperley, David C.

1994-08-01

We report for the first time an approach for natural abundance solid state 2 H NMR spectroscopy involving magic angle sample spinning (MAS), high-power 1 H decoupling (HPPD) and 1 H- 2 H cross polarization (CP). Taking tetrakis(trimethylsilyl)silane (TTMSS), adamantane, 1-chloroadamantane, hexamethylbenzene (HMB), 2,2-dimethyl-1,3-propanediol (DMPD) and 2-hydroxymethyl-2-methyl-1,3-propanediol (HMPD) as examples, it has been shown that the combination of HPPD and MAS can be applied readily to study rotator phase solids, allowing isotropic peaks arising from chemically inequivalent 2 H nuclei to be resolved. For natural abundance samples of TTMSS and chloroadamantane, it has been shown that 2 H CP/HPPD/MAS NMR experiments, involving polarization transfer from 1 H to 2 H, may provide considerable sensitivity enhancement in comparison with single pulse experiments.

Natural abundance high-resolution solid state 2 H NMR spectroscopy

NASA Astrophysics Data System (ADS)

Aliev, Abil E.; Harris, Kenneth D. M.; Apperley, David C.

1994-08-01

We report for the first time an approach for natural abundance solid state 2H NMR spectroscopy involving magic angle sample spinning (MAS), high-power 1H decoupling (HPPD) and 1H- 2H cross polarization (CP). Taking tetrakis(trimethylsilyl)silane (TTMSS), adamantane, 1-chloroadamantane, hexamethylbenzene (HMB), 2,2-dimethyl-1,3-propanediol (DMPD) and 2-hydroxymethyl-2-methyl-1,3-propanediol (HMPD) as examples, it has been shown that the combination of HPPD and MAS can be applied readily to study rotator phase solids, allowing isotropic peaks arising from chemically inequivalent 2H nuclei to be resolved. For natural abundance samples of TTMSS and chloroadamantane, it has been shown that 2H CP/HPPD/MAS NMR experiments, involving polarization transfer from 1H to 2H, may provide considerable sensitivity enhancement in comparison with single pulse experiments.

A new magnetic nanodiamond/graphene oxide hybrid (Fe3O4@ND@GO) material for pre-concentration and sensitive determination of sildenafil in alleged herbal aphrodisiacs by HPLC-DAD system.

PubMed

Yilmaz, Erkan; Ulusoy, Halil İbrahim; Demir, Özge; Soylak, Mustafa

2018-05-01

A sensitive analytical methodology was investigated to concentrate and determine of sildenafil citrate (SLC) present at trace level in herbal supplementary products. The proposed method is based on simple and sensitive pre-concentration of SLC by using magnetic solid phase extraction with new developed magnetic nanodiamond/graphene oxide hybrid (Fe 3 O 4 @ND@GO) material as a sorbent. Experimental variables affecting the extraction efficiency of SLC like; pH, sample volume, eluent type and volume, extraction time and amount of adsorbent were studied and optimized in detail. Determination of sildenafil citrate after magnetic solid phase extraction (MSPE) was carried out by HPLC-DAD system. The morphology, composition, and properties of the synthesized hybrid material was characterized by Fourier transform infrared spectrometry (FT-IR), Raman spectrometry (Raman), X-ray diffraction spectrometry (XRD), scanning electron microscopy (SEM), mapping photographs, zeta potential analyzer, and BET surface area analysis. Under optimized conditions, linear range was ranged from 5.00 to 250.00 ng mL -1 with R 2 of 0.9952. The limit of detection (LOD) was 1.49 ng mL -1 and the recoveries at two spiked levels were ranged from 94.0 to 104.1% with the relative standard deviation (RSD) < 7.1% (n = 5). The enhancement factor (EF) was 86.9. The results show that the combination MSPE with HPLC-DAD is a suitable and sensitive method for the determination of SLC in real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Pharmaceutical Applications of Relaxation Filter-Selective Signal Excitation Methods for ¹⁹F Solid-State Nuclear Magnetic Resonance: Case Study With Atorvastatin in Dosage Formulation.

PubMed

Asada, Mamiko Nasu; Nemoto, Takayuki; Mimura, Hisashi

2016-03-01

We recently developed several new relaxation filter-selective signal excitation (RFS) methods for (13)C solid-state nuclear magnetic resonance (NMR) that allow (13)C signal extraction of the target components from pharmaceuticals. These methods were successful in not only qualification but also quantitation over the wide range of 5% to 100%. Here, we aimed to improve the sensitivity of these methods and initially applied them to (19)F solid-state NMR, on the basis that the fluorine atom is one of the most sensitive NMR-active nuclei. For testing, we selected atorvastatin calcium (ATC), an antilipid BCS class II drug that inhibits 3-hydroxy-3-methylglutaryl-coenzyme A reductase and is marketed in crystalline and amorphous forms. Tablets were obtained from 2 generic drug suppliers, and the ATC content occurred mainly as an amorphous form. Using the RFS method with (19)F solid-state NMR, we succeeded in qualifying trace amounts (less than 0.5% w/w level) of crystalline phase (Form I) of ATC in the tablets. RFS methods with (19)F solid-state NMR are practical and time efficient and can contribute not only to the study of pharmaceutical drugs, including those with small amounts of a highly potent active ingredient within a formulated product, but also to the study of fluoropolymers in material sciences. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

40 CFR 227.32 - Liquid, suspended particulate, and solid phases of a material.

Code of Federal Regulations, 2010 CFR

2010-07-01

... solid phases of a material. 227.32 Section 227.32 Protection of Environment ENVIRONMENTAL PROTECTION... MATERIALS Definitions § 227.32 Liquid, suspended particulate, and solid phases of a material. (a) For the... obtained above prior to centrifugation and filtration. The solid phase includes all material settling to...

40 CFR 227.32 - Liquid, suspended particulate, and solid phases of a material.

Code of Federal Regulations, 2011 CFR

2011-07-01

... solid phases of a material. 227.32 Section 227.32 Protection of Environment ENVIRONMENTAL PROTECTION... MATERIALS Definitions § 227.32 Liquid, suspended particulate, and solid phases of a material. (a) For the... obtained above prior to centrifugation and filtration. The solid phase includes all material settling to...

Impact of the volume of gaseous phase in closed reactors on ANC results and modelling

NASA Astrophysics Data System (ADS)

Drapeau, Clémentine; Delolme, Cécile; Lassabatere, Laurent; Blanc, Denise

2016-04-01

The understanding of the geochemical behavior of polluted solid materials is often challenging and requires huge expenses of time and money. Nevertheless, given the increasing amounts of polluted solid materials and related risks for the environment, it is more and more crucial to understand the leaching of majors and trace metals elements from these matrices. In the designs of methods to quantify pollutant solubilization, the combination of experimental procedures with modeling approaches has recently gained attention. Among usual methods, some rely on the association of ANC and geochemical modeling. ANC experiments - Acid Neutralization Capacity - consists in adding known quantities of acid or base to a mixture of water and contaminated solid materials at a given liquid / solid ratio in closed reactors. Reactors are agitated for 48h and then pH, conductivity, redox potential, carbon, majors and heavy metal solubilized are quantified. However, in most cases, the amounts of matrix and water do not reach the total volume of reactors, leaving some space for air (gaseous phase). Despite this fact, no clear indication is given in standard procedures about the effect of this gaseous phase. Even worse, the gaseous phase is never accounted for when exploiting or modeling ANC data. The gaseous phase may exchange CO2 with the solution, which may, in turn, impact both pH and element release. This study lies within the most general framework for the use of geochemical modeling for the prediction of ANC results for the case of pure phases to real phase assemblages. In this study, we focus on the effect of the gaseous phase on ANC experiments on different mineral phases through geochemical modeling. To do so, we use PHREEQC code to model the evolution of pH and element release (including majors and heavy metals) when several matrices are put in contact with acid or base. We model the following scenarios for the gaseous phase: no gas, contact with the atmosphere (open system) and real reactors conditions (semi-closed systems). The solid phases tested are pure phases (calcite, sulfides, etc.) and synthetic assemblages mimicking complex polluted matrices. The modeling clearly shows that the systems are sensitive to the opening to the atmosphere. If the open system and the system with no gas are entirely different, "real" reactors also differ significantly from the other systems. Apparently, the presence of the gaseous phase in reactors greatly impacts pH and element release. This parameter should be accounted for in ANC experimental procedures and modeling. In addition to this numerical study, experimental results, previously obtained for urban polluted sediments, are analyzed in lights of the findings of the numerical study. This step allows us to strengthen conclusions and to pinpoint at the necessity to account for the gaseous phase when performing and modeling ANC experiments.

Development of sensitive determination method for fungicides from environmental water samples with Titanate nanotube array micro-solid phase extraction prior to high performance liquid chromatography.

PubMed

Huang, Yunrui; Zhou, Qingxiang; Xie, Guohong

2013-01-01

Fungicides have been widely used throughout the world, and the resulted pollution has absorbed great attention in recent years. Present study described an effective measurement technique for fungicides including thiram, metalaxyl, diethofencarb, myclobutanil and tebuconazole in environmental water samples. A micro-solid phase extraction (μSPE) was developed utilizing ordered TiO(2) nanotube array for determination of target fungicides prior to a high performance liquid chromatography (HPLC). The experimental results indicated that TiO(2) nanotube arrays demonstrated excellent merits on the preconcentration of fungicides, and excellent linear relationship between peak area and the concentration of fungicides was obtained in the range of 0.1-50 μg L(-1). The detection limits for the targeted fungicides were in the range of 0.016-0.086 μg L(-1) (S/N=3). Four real environmental water samples were used to validate the applicability of the proposed method, and good spiked recoveries in the range of 73.9-114% were achieved. A comparison of present method with conventional solid phase extraction was made and the results exhibited that proposed method resulted in better recoveries. The results demonstrated that this μ-SPE technique was a viable alternative for the analysis of fungicides in complex samples. Copyright © 2012 Elsevier Ltd. All rights reserved.

Determination of Three Organochlorine Pesticides in Aqueous Samples by Solid-Phase Extraction Based on Natural Nano Diatomite in Packed Syringe Coupled to Gas Chromatography-Mass Spectrometry.

PubMed

Taghani, Abdollah; Goudarzi, Nasser; Bagherian, Ghadamali; Chamjangali, Mansour Arab

2017-01-01

A rapid, simple, and sensitive technique is proposed based on a miniaturized solid-phase extraction method named mictroextraction in a packed syringe coupled with gas chromatography-mass spectrometry for the preconcentration and determination of three organochlorine pesticides. These include hexachlorobenzene, heptachlor and aldrine in aqueous samples. For the first time, the natural nano diatomite is used a sorbent. Based on this technique, 6.0 mg of the nano sorbent is inserted in a syringe between two polypropylene frits. The analytes would be adsorbed on the solid phase, and would subsequently be eluted using organic solvents. The influence of some important parameters, such as the solution pH, type and volume of the organic desorption solvent, and amount of sorbent on the extraction efficiency of the selected pesticides, is investigated. The proposed method shows good linearity in the range of 0.1 - 40.0 μg L -1 , and at low limits of detection in the range of 0.02 - 0.13 μg L -1 using the selected ion-monitoring mode. The reproducibility of this method was found to be in the range of 3.5 - 11.1% for the understudied pesticides. In order to evaluate the matrix effect, the developed method is also applied to the preconcentration and determination of the selected pesticides in different water samples.

Rapid solid-phase microwave synthesis of highly photoluminescent nitrogen-doped carbon dots for Fe3+ detection and cellular bioimaging

NASA Astrophysics Data System (ADS)

He, Guili; Xu, Minghan; Shu, Mengjun; Li, Xiaolin; Yang, Zhi; Zhang, Liling; Su, Yanjie; Hu, Nantao; Zhang, Yafei

2016-09-01

Recently, carbon dots (CDs) have been playing an increasingly important role in industrial production and biomedical field because of their excellent properties. As such, finding an efficient method to quickly synthesize a large scale of relatively high purity CDs is of great interest. Herein, a facile and novel microwave method has been applied to prepare nitrogen doped CDs (N-doped CDs) within 8 min using L-glutamic acid as the sole reaction precursor in the solid phase condition. The as-prepared N-doped CDs with an average size of 1.64 nm are well dispersed in aqueous solution. The photoluminescence of N-doped CDs is pH-sensitive and excitation-dependent. The N-doped CDs show a strong blue fluorescence with relatively high fluorescent quantum yield of 41.2%, which remains stable even under high ionic strength. Since the surface is rich in oxygen-containing functional groups, N-doped CDs can be applied to selectively detect Fe3+ with the limit of detection of 10-5 M. In addition, they are also used for cellular bioimaging because of their high fluorescent intensity and nearly zero cytotoxicity. The solid-phase microwave method seems to be an effective strategy to rapidly obtain high quality N-doped CDs and expands their applications in ion detection and cellular bioimaging.

Highly selective solid-phase extraction and large volume injection for the robust gas chromatography-mass spectrometric analysis of TCA and TBA in wines.

PubMed

Insa, S; Anticó, E; Ferreira, V

2005-09-30

A reliable solid-phase extraction (SPE) method for the simultaneous determination of 2,4,6-trichloroanisole (TCA) and 2,4,6-tribromoanisole (TBA) in wines has been developed. In the proposed procedure 50 mL of wine are extracted in a 1 mL cartridge filled with 50 mg of LiChrolut EN resins. Most wine volatiles are washed up with 12.5 mL of a water:methanol solution (70%, v/v) containing 1% of NaHCO3. Analytes are further eluted with 0.6 mL of dichloromethane. A 40 microL aliquot of this extract is directly injected into a PTV injector operated in the solvent split mode, and analysed by gas chromatography (GC)-ion trap mass spectrometry using the selected ion storage mode. The solid-phase extraction, including sample volume and rinsing and elution solvents, and the large volume GC injection have been carefully evaluated and optimized. The resulting method is precise (RSD (%) < 6% at 100 ng L(-1)), sensitive (LOD were 0.2 and 0.4 ng/L for TCA and TBA, respectively), robust (the absolute recoveries of both analytes are higher than 80% and consistent wine to wine) and friendly to the GC-MS system (the extract is clean, simple and free from non-volatiles).

Analysis of volatile organic compounds in pleural effusions by headspace solid-phase microextraction coupled with cryotrap gas chromatography and mass spectrometry.

PubMed

Huang, Zhongping; Zhang, Jie; Zhang, Peipei; Wang, Hong; Pan, Zaifa; Wang, Lili

2016-07-01

Headspace solid-phase microextraction coupled with cryotrap gas chromatography and mass spectrometry was applied to the analysis of volatile organic compounds in pleural effusions. The highly volatile organic compounds were separated successfully with high sensitivity by the employment of a cryotrap device, with the construction of a cold column head by freezing a segment of metal capillary with liquid nitrogen. A total of 76 volatile organic compounds were identified in 50 pleural effusion samples (20 malignant effusions and 30 benign effusions). Among them, 34 more volatile organic compounds were detected with the retention time less than 8 min, by comparing with the normal headspace solid-phase microextraction coupled with gas chromatography and mass spectrometry method. Furthermore, 24 volatile organic compounds with high occurrence frequency in pleural effusion samples, 18 of which with the retention time less than 8 min, were selected for the comparative analysis. The results of average peak area comparison and box-plot analysis showed that except for cyclohexanone, 2-ethyl-1-hexanol, and tetramethylbenzene, which have been reported as potential cancer biomarkers, cyclohexanol, dichloromethane, ethyl acetate, n-heptane, ethylbenzene, and xylene also had differential expression between malignant and benign effusions. Therefore, the proposed approach was valuable for the comprehensive characterization of volatile organic compounds in pleural effusions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of solid-phase microextraction coupled with liquid chromatography for analysis of tramadol in brain tissue using its molecularly imprinted polymer.

PubMed

Habibi-Khorasani, Monireh; Mohammadpour, Amir Hooshang; Mohajeri, Seyed Ahmad

2017-02-01

In this work, performance of a molecularly imprinted polymer (MIP) as a selective solid-phase microextraction sorbent for the extraction and enrichment of tramadol in aqueous solution and rabbit brain tissue, is described. Binding properties of MIPs were studied in comparison with their nonimprinted polymer (NIP). Ten milligrams of the optimized MIP was then evaluated as a sorbent, for preconcentration, in molecularly imprinted solid-phase microextraction (MISPME) of tramadol from aqueous solution and rabbit brain tissue. The analytical method was calibrated in the range of 0.004 ppm (4 ng mL -1 ) and 10 ppm (10 μg mL -1 ) in aqueous media and in the ranges of 0.01 and 10 ppm in rabbit brain tissue, respectively. The results indicated significantly higher binding affinity of MIPs to tramadol, in comparison with NIP. The MISPME procedure was developed and optimized with a recovery of 81.12-107.54% in aqueous solution and 76.16-91.20% in rabbit brain tissue. The inter- and intra-day variation values were <8.24 and 5.06%, respectively. Finally the calibrated method was applied for determination of tramadol in real rabbit brain tissue samples after administration of a lethal dose. Our data demonstrated the potential of MISPME for rapid, sensitive and cost-effective sample analysis. Copyright © 2016 John Wiley & Sons, Ltd.

Biological treatment of soils contaminated with hydrophobic organics using slurry- and solid-phase techniques

NASA Astrophysics Data System (ADS)

Cassidy, Daniel H.; Irvine, Robert L.

1995-10-01

Both slurry-phase and solid-phase bioremediation are effective ex situ soil decontamination methods. Slurrying is energy intensive relative to solid-phase treatment, but provides homogenization and uniform nutrient distribution. Limited contaminant bioavailability at concentrations above the required cleanup level reduces biodegradation rates and renders solid phase bioremediation more cost effective than complete treatment in a bio-slurry reactor. Slurrying followed by solid-phase bioremediation combines the advantages and minimizes the weaknesses of each treatment method when used alone. A biological treatment system consisting of slurrying followed by aeration in solid phase bioreactors was developed and tested in the laboratory using a silty clay loam contaminated with diesel fuel. The first set of experiments was designed to determine the impact of the water content and mixing time during slurrying on the rate an extent of contaminant removal in continuously aerated solid phase bioreactors. The second set of experiments compared the volatile and total diesel fuel removal in solid phase bioreactors using periodic and continuous aeration strategies. Results showed that slurrying for 1.5 hours at a water content less than saturation markedly increased the rate and extent of contaminant biodegradation in the solid phase bioreactors compared with soil having no slurry pretreatment. Slurrying the soil at or above its saturation moisture content resulted in lengthy dewatering times which prohibited aeration, thereby delaying the onset of biological treatment in the solid phase bioreactors. Results also showed that properly operated periodic aeration can provide less volatile contaminant removal and a grater fraction of biological contaminant removal than continuous aeration.

Quantitative analysis of flavanones from citrus fruits by using mesoporous molecular sieve-based miniaturized solid phase extraction coupled to ultrahigh-performance liquid chromatography and quadrupole time-of-flight mass spectrometry.

PubMed

Cao, Wan; Ye, Li-Hong; Cao, Jun; Xu, Jing-Jing; Peng, Li-Qing; Zhu, Qiong-Yao; Zhang, Qian-Yun; Hu, Shuai-Shuai

2015-08-07

An analytical procedure based on miniaturized solid phase extraction (SPE) and ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry was developed and validated for determination of six flavanones in Citrus fruits. The mesoporous molecular sieve SBA-15 as a solid sorbent was characterised by Fourier transform-infrared spectroscopy and scanning electron microscopy. Additionally, compared with reported extraction techniques, the mesoporous SBA-15 based SPE method possessed the advantages of shorter analysis time and higher sensitivity. Furthermore, considering the different nature of the tested compounds, all of the parameters, including the SBA-15 amount, solution pH, elution solvent, and the sorbent type, were investigated in detail. Under the optimum condition, the instrumental detection and quantitation limits calculated were less than 4.26 and 14.29ngmL(-1), respectively. The recoveries obtained for all the analytes were ranging from 89.22% to 103.46%. The experimental results suggested that SBA-15 was a promising material for the purification and enrichment of target flavanones from complex citrus fruit samples. Copyright © 2015 Elsevier B.V. All rights reserved.

A Convenient Method for Extraction and Analysis with High-Pressure Liquid Chromatography of Catecholamine Neurotransmitters and Their Metabolites.

PubMed

Xie, Li; Chen, Liqin; Gu, Pan; Wei, Lanlan; Kang, Xuejun

2018-03-01

The extraction and analysis of catecholamine neurotransmitters in biological fluids is of great importance in assessing nervous system function and related diseases, but their precise measurement is still a challenge. Many protocols have been described for neurotransmitter measurement by a variety of instruments, including high-pressure liquid chromatography (HPLC). However, there are shortcomings, such as complicated operation or hard-to-detect multiple targets, which cannot be avoided, and presently, the dominant analysis technique is still HPLC coupled with sensitive electrochemical or fluorimetric detection, due to its high sensitivity and good selectivity. Here, a detailed protocol is described for the pretreatment and detection of catecholamines with high pressure liquid chromatography with electrochemical detection (HPLC-ECD) in real urine samples of infants, using electrospun composite nanofibers composed of polymeric crown ether with polystyrene as adsorbent, also known as the packed-fiber solid phase extraction (PFSPE) method. We show how urine samples can be easily precleaned by a nanofiber-packed solid phase column, and how the analytes in the sample can be rapidly enriched, desorbed, and detected on an ECD system. PFSPE greatly simplifies the pretreatment procedures for biological samples, allowing for decreased time, expense, and reduction of the loss of targets. Overall, this work illustrates a simple and convenient protocol for solid-phase extraction coupled to an HPLC-ECD system for simultaneous determination of three monoamine neurotransmitters (norepinephrine (NE), epinephrine (E), dopamine (DA)) and two of their metabolites (3-methoxy-4-hydroxyphenylglycol (MHPG) and 3,4-dihydroxy-phenylacetic acid (DOPAC)) in infants' urine. The established protocol was applied to assess the differences of urinary catecholamines and their metabolites between high-risk infants with perinatal brain damage and healthy controls. Comparative analysis revealed a significant difference in urinary MHPG between the two groups, indicating that the catecholamine metabolites may be an important candidate marker for early diagnosis of cases at risk for brain damage in infants.

Rapid determination of six carcinogenic primary aromatic amines in mainstream cigarette smoke by two-dimensional online solid phase extraction combined with liquid chromatography tandem mass spectrometry.

PubMed

Bie, Zhenying; Lu, Wei; Zhu, You; Chen, Yusong; Ren, Hubo; Ji, Lishun

2017-01-27

A fully automated, rapid, and reliable method for simultaneous determination of six carcinogenic primary aromatic amines (AAs), including o-toluidine (o-TOL), 2, 6-dimethylaniline (2, 6-DMA), o-anisidine (o-ASD), 1-naphthylamine (1-ANP), 2-naphthylamine (2-ANP), and 4-aminobiphenyl (4-ABP), in mainstream cigarette smoke was established. The proposed method was based on two-dimensional online solid phase extraction combined with liquid chromatography tandem mass spectrometry (SPE/LC-MS/MS). The particulate phase of the mainstream cigarette smoke was collected on a Cambridge filter pad and pretreated via ultrasonic extraction with 2% formic acid (FA), while the gas phase was trapped by 2% FA without pretreatment for determination. The two-dimensional online SPE comprised of two cartridges with different absorption characteristics was applied for sample pretreatment. Analysis was performed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) under multiple reaction monitoring mode. Each sample required about 0.5h for solid phase extraction and analysis. The limit of detections (LODs) for six AAs ranged from 0.04 to 0.58ng/cig and recoveries were within 84.5%-122.9%. The relative standard deviations of intra- and inter-day tests for 3R4F reference cigarette were less than 6% and 7%, respectively, while no more than 7% and 8% separately for a type of Virginia cigarette. The proposed method enabled minimum sample pretreatment, full automation, and high throughput with high selectivity, sensitivity, and accuracy. As a part of the validation procedure, fifteen brands of cigarettes were tested by the designed method. Copyright © 2016 Elsevier B.V. All rights reserved.

In Situ Solid-State Reactions Monitored by X-ray Absorption Spectroscopy: Temperature-Induced Proton Transfer Leads to Chemical Shifts.

PubMed

Stevens, Joanna S; Walczak, Monika; Jaye, Cherno; Fischer, Daniel A

2016-10-24

The dramatic colour and phase alteration with the solid-state, temperature-dependent reaction between squaric acid and 4,4'-bipyridine has been probed in situ with X-ray absorption spectroscopy. The electronic and chemical sensitivity to the local atomic environment through chemical shifts in the near-edge X-ray absorption fine structure (NEXAFS) revealed proton transfer from the acid to the bipyridine base through the change in nitrogen protonation state in the high-temperature form. Direct detection of proton transfer coupled with structural analysis elucidates the nature of the solid-state process, with intermolecular proton transfer occurring along an acid-base chain followed by a domino effect to the subsequent acid-base chains, leading to the rapid migration along the length of the crystal. NEXAFS thereby conveys the ability to monitor the nature of solid-state chemical reactions in situ, without the need for a priori information or long-range order. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photoelectric characterization of fabricated dye-sensitized solar cell using dye extracted from red Siahkooti fruit as natural sensitizer

NASA Astrophysics Data System (ADS)

Mozaffari, Sayed Ahmad; Saeidi, Mahsa; Rahmanian, Reza

2015-05-01

Natural dye extracted from Siahkooti fruit with/without purification by solid phase extraction (SPE) technique was used in the fabrication of DSSC as natural sensitizer. The UV-Vis absorption spectroscopy and Fourier transform infrared (FTIR) were employed to indicate the presence of anthocyanins in the fruit of red Siahkooti. The photoelectrochemical performance and the efficiency of assembled DSSC using Siahkooti fruit dye extract were evaluated and efficiency enhancement was obtained by a preliminary purification of extracted dye. The efficiency and fill factor of the DSSC using purified Siahkooti fruit dye were 0.32% and 0.73%, respectively. The results successfully showed that the DSSC, using Siahkooti fruit extract as a dye sensitizer, is useful for the preparation of environmentally friendly, low-cost, renewable and clean sources of energy.

Microchannel plate special nuclear materials sensor

NASA Astrophysics Data System (ADS)

Feller, W. B.; White, P. L.; White, P. B.; Siegmund, O. H. W.; Martin, A. P.; Vallerga, J. V.

2011-10-01

Nova Scientific Inc., is developing for the Domestic Nuclear Detection Office (DNDO SBIR #HSHQDC-08-C-00190), a solid-state, high-efficiency neutron detection alternative to 3He gas tubes, using neutron-sensitive microchannel plates (MCPs) containing 10B and/or Gd. This work directly supports DNDO development of technologies designed to detect and interdict nuclear weapons or illicit nuclear materials. Neutron-sensitized MCPs have been shown theoretically and more recently experimentally, to be capable of thermal neutron detection efficiencies equivalent to 3He gas tubes. Although typical solid-state neutron detectors typically have an intrinsic gamma sensitivity orders of magnitude higher than that of 3He gas detectors, we dramatically reduce gamma sensitivity by combining a novel electronic coincidence rejection scheme, employing a separate but enveloping gamma scintillator. This has already resulted in a measured gamma rejection ratio equal to a small 3He tube, without in principle sacrificing neutron detection efficiency. Ongoing improvements to the MCP performance as well as the coincidence counting geometry will be described. Repeated testing and validation with a 252Cf source has been underway throughout the Phase II SBIR program, with ongoing comparisons to a small commercial 3He gas tube. Finally, further component improvements and efforts toward integration maturity are underway, with the goal of establishing functional prototypes for SNM field testing.

Synthesis and study on the luminescence properties of cadmium borate phosphors

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

Annalakshmi, O.; Jose, M.T., E-mail: mtjosein@yahoo.co.in; Venkatraman, B.

2014-02-01

Highlights: • Cadmium borate synthesized by solid state sintering technique. • Neutron sensitivity of the material ten times that of TLD-600. • Gamma sensitivity is found to be twice that of TLD-100. • Gamma response is linear from 0.1 to 10{sup 3} mGy. - Abstract: Cadmium borate compound prepared through wet chemical reaction from the starting chemicals followed by high temperature solid state synthesis below the melting point to get the final TL phosphor powder. Phase purity and bond details of cadmium borate crystals are characterized using X-ray diffraction technique and infrared spectroscopy. Feasibility of these materials for radiation dosimetrymore » applications was studied after gamma and neutron irradiation. Gamma irradiation of undoped phosphors show a single peak around 185 °C whereas doping with gadolinium and silver, new more intense peak observed at 290 °C. Irradiation to thermal neutrons revealed single peak around 170 °C for all the phosphors. TL emission spectra and photoluminescence (PL) studies were also carried out on the phosphors. These borate materials are found to be highly sensitive to neutrons and hence can be used for neutron detection. Neutron sensitivity of the material is about ten times that of TLD-600.« less

Transitiometric analysis of solid II/solid I transition in anhydrous theophylline.

PubMed

Legendre, Bernard; Randzio, Stanislaw L

2007-10-01

For the first time, with the use of a high sensitivity, low heating rate, scanning transitiometry, it was possible to distinguish and characterise the polymorphic equilibrium transition between forms II and I in anhydrous theophylline. In this manner it was univocally proved, that forms II and I in theophylline are enantiotropically related. The temperature and enthalpy for that transition are as follows: T(trs)(II/I)=536.8+/-2.2K; Delta(trs)H(II/I)=1.99+/-0.09 kJ/mol. Making use of advantages of very slow heating rate and of a high energetic sensitivity of the transitiometer it was possible to observe in detail the polymorphic transition followed by melting of high temperature form I and to stop the solid I-liquid transition at a desired point of equilibrium. Such a solid I-liquid equilibrium could be stabilised and then displaced back to the crystallisation of form I with an adequate use of a precise temperature programming. In such a way a pure single phase of form I of theophylline was prepared. This fact was confirmed by X-ray powder diffraction patterns and calorimetric traces of fusion of the crystallised product. The temperature and enthalpy of the form I-liquid transition are as follows: T(fus)(I)=546.5+/-0.2K and Delta(fus)H(I)=29.37+/-0.29 kJ/mol.

Formation of pH-sensitive cationic liposomes from a binary mixture of monoalkylated primary amine and cholesterol.

PubMed

Cui, Zhong-Kai; Bouisse, Anne; Cottenye, Nicolas; Lafleur, Michel

2012-09-25

It has been shown that mixtures of monoalkylated amphiphiles and sterols can form liquid-ordered (lo) lamellar phases. These bilayers can be extruded using conventional methods to obtain large unilamellar vesicles (LUVs) that have very low permeability and a specific response to a given stimulus. For example, pH variations can trigger the release from LUVs formed with palmitic acid and sterols. In the present work, the possibility to form non phospholipid liposomes with mixtures of stearylamine (SA) and cholesterol (Chol) was investigated. The phase behavior of these mixtures was characterized by differential scanning calorimetry, infrared, and (2)H NMR spectroscopy. It is found that this particular mixture can form a lo lamellar phase that is pH-sensitive as the system undergoes a transition from a lo phase to a solid state when pH is increased from 5.5 to 12. LUVs have been successfully extruded from equimolar SA/Chol mixtures. Release experiments as a function of time revealed the relatively low permeability of these systems. The fact that the stability of these liposomes is pH dependent implies that these LUVs display an interesting potential as new cationic carriers for pH-triggered release. This is the first report of non phospholipid liposomes with high sterol content combining an overall positive charge and pH-sensitivity.

Sensitive analysis of blonanserin, a novel antipsychotic agent, in human plasma by ultra-performance liquid chromatography-tandem mass spectrometry.

PubMed

Ogawa, Tadashi; Hattori, Hideki; Kaneko, Rina; Ito, Kenjiro; Iwai, Masayo; Mizutani, Yoko; Arinobu, Tetsuya; Ishii, Akira; Suzuki, Osamu; Seno, Hiroshi

2010-01-01

A rapid and sensitive method for analysis of blonanserin in human plasma by ultra-performance liquid chromatography-tandem mass spectrometry is presented. After pretreatment of a plasma sample by solid-phase extraction, blonanserin was analyzed by the system with a C(18) column. This method gave satisfactory recovery rates, reproducibility, and good linearity of calibration curve in the range of 0.01-10.0 ng/mL for quality control samples spiked with blonanserin. The detection limit was as low as 1 pg/mL. This method seems very useful in forensic and clinical toxicology and pharmacokinetic studies.

A simple and sensitive quantitation of N,N-dimethyltryptamine by gas chromatography with surface ionization detection.

PubMed

Ishii, A; Seno, H; Suzuki, O; Hattori, H; Kumazawa, T

1997-01-01

A simple and sensitive method for determination of N,N-dimethyltryptamine (DMT) by gas chromatography (GC) with surface ionization detection (SID) is presented. Whole blood or urine, containing DMT and gramine (internal standard), was subjected to solid-phase extraction with a Sep-Pak C18 cartridge before analysis by GC-SID. The calibration curve was linear in the DMT range of 1.25-20 ng/mL blood or urine. The detection limit of DMT was about 0.5 ng/mL (10 pg on-column). The recovery of both DMT and gramine spiked in biological fluids was above 86%.

An enzyme immunoassay for rat growth hormone - Applications to the study of growth hormone variants

NASA Technical Reports Server (NTRS)

Farrington, Marianne A.; Hymer, W. C.

1987-01-01

A sensitive and specific competitive enzyme immunoassay for rat growth hormone (GH) is described and its use in the detection of GH variants is demonstrated. In the present assay, soluble GH and GH adsorbed to a solid-phase support compete for monkey anti-GH antibody binding sites. The immobilized antibody-GH complex is detected and quantified using goat antimonkey immunoglobin G covalently conjugated to horseradish peroxidase. It is noted that the assay can be performed in 27 hours and that sensitivities in the range of 0.19 to 25 ng can be obtained in the region of 10 to 90 percent binding.

Seasonal multiphase equilibria in the atmospheres of Titan and Pluto

NASA Astrophysics Data System (ADS)

Tan, S. P.; Kargel, J. S.

2017-12-01

At the extremely low temperatures in Titan's upper troposphere and on Pluto's surface, the atmospheres as a whole are subject to freeze into solid solutions, not pure ices. The presence of the solid phases introduces conditions with rich phase equilibria upon seasonal changes, even if the temperature undergoes only small changes. For the first time, the profile of atmospheric methane in Titan's troposphere will be reproduced complete with the solid solutions. This means that the freezing point, i.e. the altitude where the first solid phase appears, is determined. The seasonal change will also be evaluated both at the equator and the northern polar region. For Pluto, also for the first time, the seasonal solid-vapor equilibria will be evaluated. The fate of the two solid phases, the methane-rich and carbon-monoxide-rich solid solutions, will be analyzed upon temperature and pressure changes. Such investigations are enabled by the development of a molecular-based thermodynamic model for cryogenic chemical systems, referred to as CRYOCHEM, which includes solid solutions in its phase-equilibria calculations. The atmospheres of Titan and Pluto are modeled as ternary gas mixtures: nitrogen-methane-ethane and nitrogen-methane-carbon monoxide, respectively. Calculations using CRYOCHEM can provide us with compositions not only in two-phase equilibria, but also that in three-phase equilibria. Densities of all phases involved will also be calculated. For Titan, density inversion between liquid and solid phases will be identified and presented. In the inversion, the density of solid phase is less than that in the liquid phase. The method and results of this work will be useful for further investigations and modeling on the atmospheres of Titan, Pluto, and other bodies with similar conditions in the Solar System and beyond.

Leukotriene B4 catabolism: quantitation of leukotriene B4 and its omega-oxidation products by reversed-phase high-performance liquid chromatography.

PubMed

Shak, S

1987-01-01

LTB4 and its omega-oxidation products may be rapidly, sensitively, and specifically quantitated by the methods of solid-phase extraction and reversed-phase high-performance liquid chromatography (HPLC), which are described in this chapter. Although other techniques, such as radioimmunoassay or gas chromatography-mass spectrometry, may be utilized for quantitative analysis of the lipoxygenase products of arachidonic acid, only the technique of reversed-phase HPLC can quantitate as many as 10 metabolites in a single analysis, without prior derivatization. In this chapter, we also reviewed the chromatographic theory which we utilized in order to optimize reversed-phase HPLC analysis of LTB4 and its omega-oxidation products. With this information and a gradient HPLC system, it is possible for any investigator to develop a powerful assay for the potent inflammatory mediator, LTB4, or for any other lipoxygenase product of arachidonic acid.

Materials research for passive solar systems: Solid-state phase-change materials

NASA Astrophysics Data System (ADS)

Benson, D. K.; Webb, J. D.; Burrows, R. W.; McFadden, J. D. O.; Christensen, C.

1985-03-01

A set of solid-state phase-change materials is being evaluated for possible use in passive solar thermal energy storage systems. The most promising materials are organic solid solutions of pentaerythritol (C5H12O4), pentaglycerinve (C5H12O3), and neopentyl glycol (C5H12O2). Solid solution mixtures of these compounds can be tailored so that they exhibit solid-to-solid phase transformations at any desired temperature between 25 C and 188 C, and have latent heats of transformation etween 20 and 70 cal/g. Transformation temperatures, specific heats, and latent heats of transformation have been measured for a number of these materials. Limited cyclic experiments suggest that the solid solutions are stable. These phase-change materials exhibit large amounts of undercooling; however, the addition of certain nucleating agents as particulate dispersions in the solid phase-change material greatly reduces this effect. Computer simulations suggest that the use of an optimized solid-state phase-change material in a Trombe wall could provide better performance than a concrete Trombe wall four times thicker and nine times heavier.

Application of carbon nanotubes modified with a Keggin polyoxometalate as a new sorbent for the hollow-fiber micro-solid-phase extraction of trace naproxen in hair samples with fluorescence spectrophotometry using factorial experimental design.

PubMed

Naddaf, Ezzat; Ebrahimi, Mahmoud; Es'haghi, Zarrin; Bamoharram, Fatemeh Farrash

2015-07-01

A sensitive technique to determinate naproxen in hair samples was developed using hollow-fiber micro-solid-phase combined with fluorescence spectrophotometry. The incorporation of multi-walled carbon nanotubes modified with a Keggin polyoxometalate into a silica matrix prepared by the sol-gel method was reported. In this research, the Keggin carbon nanotubes /silica composite was used in the pores and lumen of a hollow fiber as the hollow-fiber micro-solid-phase extraction device. The device was used for the microextraction of the analyte from hair and water samples under the optimized conditions. An orthogonal array experimental design with an OA24 (4(6) ) matrix was employed to optimize the conditions. The effect of six factors influencing the extraction efficiency was investigated: pH, salt, volume of donor and desorption phase, extraction and desorption time. The effect of each factor was estimated using individual contributions as response functions in the screening process. Analysis of variance was employed for estimating the main significant factors and their contributions in the extraction. Calibration curve plot displayed linearity over a range of 0.2-10 ng/mL with detection limits of 0.072 and 0.08 ng/mL for hair and aqueous samples, respectively. The relative recoveries in the hair and aqueous matrices ranged from 103-95%. The relative standard deviation for fiber-to-fiber repeatability was 3.9%. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Utility of solid phase extraction for spectrophotometric determination of gold in water, jewel and ore samples.

PubMed

Amin, Alaa S

2010-12-01

A highly sensitive, selective and rapid method for the determination μg L(-1) level of Au(III) based on the rapid reaction of Au(III) with 2,3-dichloro-6-(3-carboxy-2-hydroxy-1-naphthylazo)quinoxaline (DCHNAQ) and the solid phase extraction of the colored complex with a reversed phase polymer-based C18 cartridge have been developed. The DCHNAQ reacted with Au(III) to form a violet complex of a molar ratio 3:1 [DCHNAQ to Au(III)] in the presence of 5.0 M of phosphoric acid solution and Triton X-100 medium. This complex was enriched by the solid phase extraction with a polymer-based C18 cartridge. The enrichment factor of 100 was achieved. The molar absorptivity of the complex is 2.73×10(5) l mol(-1) cm(-1) at 633 nm in the measured solution. The system obeys Beer's law in the range of 0.02-1.30 μg ml(-1), whereas the optimum concentration ranges obtained from Ringbom plot was 0.08-1.24 μg ml(-1). The relative standard deviation for ten replicates sample of 0.6 μg ml(-1) level is 1.28%. The detection and quantification limits, are 6.1 and 19.5 ng ml(-1) in the original sample. This method was applied to the determination of gold in water, jewel and ore samples with good results comparing to the GFAAS method. Copyright © 2010 Elsevier B.V. All rights reserved.

Solid deuterated water in space: detection constraints from laboratory experiments

NASA Astrophysics Data System (ADS)

Urso, R. G.; Palumbo, M. E.; Baratta, G. A.; Scirè, C.; Strazzulla, G.

2018-06-01

The comparison between astronomical spectra and laboratory experiments is fundamental to spread light on the structure and composition of ices found in interstellar dense molecular clouds and in Solar System bodies. Water is among the most abundant solid-phase species observed in these environments, and several attempts have been made to investigate the presence of its solid-phase isotopologues. In particular, the detection of the O-D stretching mode band at 4.1 μm due to both D2O and HDO within icy grain mantles is still under debate, and no detection have been reported about the presence of these species within icy bodies in the Solar System yet. In the near future, an important contribution could derive from the data acquired in the O-D stretching mode spectral range by the sensitive instruments on board the James Webb Space Telescope. With this in mind, we performed several laboratory experiments to study the O-D stretching mode band in solid mixtures containing water and deuterated water deposited in the temperature range between 17 and 155 K, in order to simulate astrophysical relevant conditions. Furthermore, samples have been studied at various temperature and irradiated with energetic ions (200 keV H+) in order to study the effects induced by both thermal and energetic processing. Our results provide some constraints on the detection of the 4.1 μm band in astronomical environments.

Sensitized Liquid Hydrazine Detonation Studies

NASA Technical Reports Server (NTRS)

Rathgeber, K. A.; Keddy, C. P.; Bunker, R. L.

1999-01-01

Vapor-phase hydrazine (N2H4) is known to be very sensitive to detonation while liquid hydrazine is very insensitive to detonation, theoretically requiring extremely high pressures to induce initiation. A review of literature on solid and liquid explosives shows that when pure explosive substances are infiltrated with gas cavities, voids, and/or different phase contaminants, the energy or shock pressure necessary to induce detonation can decrease by an order of magnitude. Tests were conducted with liquid hydrazine in a modified card-gap configuration. Sensitization was attempted by bubbling helium gas through and/or suspending ceramic microspheres in the liquid. The hydrazine was subjected to the shock pressure from a 2 lb (0.9 kg) Composition C-4 explosive charge. The hydrazine was contained in a 4 in. (10.2 cm) diameter stainless steel cylinder with a 122 in(sup 3) (2 L) volume and sealed with a polyethylene cap. Blast pressures from the events were recorded by 63 high speed pressure transducers located on three radial legs extending from 4 to 115 ft (1.2 to 35.1 in) from ground zero. Comparison of the neat hydrazine and water baseline tests with the "sensitized" hydrazine tests indicates the liquid hydrazine did not detonate under these conditions.

A simple and sensitive enzymatic method for cholesterol quantification in macrophages and foam cells

PubMed Central

Robinet, Peggy; Wang, Zeneng; Hazen, Stanley L.; Smith, Jonathan D.

2010-01-01

A precise and sensitive method for measuring cellular free and esterified cholesterol is required in order to perform studies of macrophage cholesterol loading, metabolism, storage, and efflux. Until now, the use of an enzymatic cholesterol assay, commonly used for aqueous phase plasma cholesterol assays, has not been optimized for use with solid phase samples such as cells, due to inefficient solubilization of total cholesterol in enzyme compatible solvents. We present an efficient solubilization protocol compatible with an enzymatic cholesterol assay that does not require chemical saponification or chromatographic separation. Another issue with enzyme compatible solvents is the presence of endogenous peroxides that interfere with the enzymatic cholesterol assay. We overcame this obstacle by pretreatment of the reaction solution with the enzyme catalase, which consumed endogenous peroxides resulting in reduced background and increased sensitivity in our method. Finally, we demonstrated that this method for cholesterol quantification in macrophages yields results that are comparable to those measured by stable isotope dilution gas chromatography with mass spectrometry detection. In conclusion, we describe a sensitive, simple, and high-throughput enzymatic method to quantify cholesterol in complex matrices such as cells. PMID:20688754

A reversible transition in liquid Bi under pressure.

PubMed

Emuna, M; Matityahu, S; Yahel, E; Makov, G; Greenberg, Y

2018-01-21

The electrical resistance of solid and liquid Bi has been measured at high pressures and temperatures using a novel experimental design for high sensitivity measurements utilizing a "Paris-Edinburgh" toroid large volume press. An anomalous sharp decrease in resistivity with increasing temperature at constant pressures was observed in the region beyond melting which implies a possible novel transition in the melt. The proposed transition was observed across a range of pressures both in heating and cooling cycles of the sample demonstrating its reversibility. From the measurements it was possible to determine a "phase-line" of this transition on the Bi pressure-temperature phase diagram terminating at the melting curve.

A Model to Simulate Titanium Behavior in the Iron Blast Furnace Hearth

NASA Astrophysics Data System (ADS)

Guo, Bao-Yu; Zulli, Paul; Maldonado, Daniel; Yu, Ai-Bing

2010-08-01

The erosion of hearth refractory is a major limitation to the campaign life of a blast furnace. Titanium from titania addition in the burden or tuyere injection can react with carbon and nitrogen in molten pig iron to form titanium carbonitride, giving the so-called titanium-rich scaffold or buildup on the hearth surface, to protect the hearth from subsequent erosion. In the current article, a mathematical model based on computational fluid dynamics is proposed to simulate the behavior of solid particles in the liquid iron. The model considers the fluid/solid particle flow through a packed bed, conjugated heat transfer, species transport, and thermodynamic of key chemical reactions. A region of high solid concentration is predicted at the hearth bottom surface. Regions of solid formation and dissolution can be identified, which depend on the local temperature and chemical equilibrium. The sensitivity to the key model parameters for the solid phase is analyzed. The model provides an insight into the fundamental mechanism of solid particle formation, and it may form a basic model for subsequent development to study the formation of titanium scaffold in the blast furnace hearth.

Benzocaine polymorphism: pressure-temperature phase diagram involving forms II and III.

PubMed

Gana, Inès; Barrio, Maria; Do, Bernard; Tamarit, Josep-Lluís; Céolin, René; Rietveld, Ivo B

2013-11-18

Understanding the phase behavior of an active pharmaceutical ingredient in a drug formulation is required to avoid the occurrence of sudden phase changes resulting in decrease of bioavailability in a marketed product. Benzocaine is known to possess three crystalline polymorphs, but their stability hierarchy has so far not been determined. A topological method and direct calorimetric measurements under pressure have been used to construct the topological pressure-temperature diagram of the phase relationships between the solid phases II and III, the liquid, and the vapor phase. In the process, the transition temperature between solid phases III and II and its enthalpy change have been determined. Solid phase II, which has the highest melting point, is the more stable phase under ambient conditions in this phase diagram. Surprisingly, solid phase I has not been observed during the study, even though the scarce literature data on its thermal behavior appear to indicate that it might be the most stable one of the three solid phases. Copyright © 2013 Elsevier B.V. All rights reserved.

Magnetic graphene dispersive solid phase extraction combining high performance liquid chromatography for determination of fluoroquinolones in foods.

PubMed

He, Xin; Wang, Geng Nan; Yang, Kun; Liu, Hui Zhi; Wu, Xia Jun; Wang, Jian Ping

2017-04-15

In this study, a magnetic graphene-based dispersive solid phase extraction method was developed that was combined with high performance liquid chromatography to determine the residues of fluoroquinolone drugs in foods of animal origin. During the experiments, several parameters possible influencing the extraction performance were optimized (amount of magnetic graphene, sample pH, extraction time and elution solution). This extraction method showed high absorption capacities (>6800ng) and high enrichment factors (68-79-fold) for seven fluoroquinolones. Furthermore, this absorbent could be reused for at least 40 times. The limits of detection were in the range of 0.05-0.3ng/g, and the recoveries from the standards fortified blank samples (bovine milk, chicken muscle and egg) were in the range of 82.4-108.5%. Therefore, this method could be used as a simple and sensitive tool to determine the residues of fluoroquinolones in foods of animal origin. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Developments in preparation and experimental method of solid phase microextraction fibers].

PubMed

Yi, Xu; Fu, Yujie

2004-09-01

Solid phase microextraction (SPME) is a simple and effective adsorption and desorption technique, which concentrates volatile or nonvolatile compounds from liquid samples or headspace of samples. SPME is compatible with analyte separation and detection by gas chromatography, high performance liquid chromatography, and other instrumental methods. It can provide many advantages, such as wide linear scale, low solvent and sample consumption, short analytical times, low detection limits, simple apparatus, and so on. The theory of SPME is introduced, which includes equilibrium theory and non-equilibrium theory. The novel development of fiber preparation methods and relative experimental techniques are discussed. In addition to commercial fiber preparation, different newly developed fabrication techniques, such as sol-gel, electronic deposition, carbon-base adsorption, high-temperature epoxy immobilization, are presented. Effects of extraction modes, selection of fiber coating, optimization of operating conditions, method sensitivity and precision, and systematical automation, are taken into considerations in the analytical process of SPME. A simple perspective of SPME is proposed at last.

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.

kepler's dark worlds: A low albedo for an ensemble of Neptunian and Terran exoplanets

NASA Astrophysics Data System (ADS)

Jansen, Tiffany; Kipping, David

2018-05-01

Photometric phase curves provide an important window onto exoplanetary atmospheres and potentially even their surfaces. With similar amplitudes to occultations but far longer baselines, they have a higher sensitivity to planetary photons at the expense of a more challenging data reduction in terms of long-term stability. In this work, we introduce a novel non-parametric algorithm dubbed phasma to produce clean, robust exoplanet phase curves and apply it to 115 Neptunian and 50 Terran exoplanets observed by kepler. We stack the signals to further improve signal-to-noise, and measure an average Neptunian albedo of Ag < 0.23 to 95% confidence, indicating a lack of bright clouds consistent with theoretical models. Our Terran sample provides the first constraint on the ensemble albedo of exoplanets which are most likely solid, constraining Ag < 0.42 to 95% confidence. In agreement with our constraint on the greenhouse effect, our work implies that kepler's solid planets are unlikely to resemble cloudy Venusian analogs, but rather dark Mercurian rocks.

Application of molecularly imprinted polymer based matrix solid phase dispersion for determination of fluoroquinolones, tetracyclines and sulfonamides in meat.

PubMed

Wang, Geng Nan; Zhang, Lei; Song, Yi Ping; Liu, Ju Xiang; Wang, Jian Ping

2017-10-15

In this study, a type of novel mixed-template molecularly imprinted polymer was synthesized that was able to recognize 8 fluoroquinolones, 8 sulfonamides and 4 tetracyclines simultaneously with recoveries higher than 92%. Then the polymer was used to develop a matrix solid phase dispersion method for simultaneous extraction of the 20 drugs in pork followed by determination with ultra performance liquid chromatography. During the experiments, the MMIP amount, washing solvent and elution solvent were optimized respectively. The limits of detection of this method for the 20 drugs in pork were in the range of 0.5-3.0ngg -1 , and the intra-day and inter-day recoveries from the fortified blank samples were in the range of 74.5%-102.7%. Therefore, this method could be used as a rapid, simple, specific and sensitive method for multi-determination of the residues of the three classes of drugs in meat. Copyright © 2017 Elsevier B.V. All rights reserved.

The global phase diagram of the Gay-Berne model

NASA Astrophysics Data System (ADS)

de Miguel, Enrique; Vega, Carlos

2002-10-01

The phase diagram of the Gay-Berne model with anisotropy parameters κ=3, κ'=5 has been evaluated by means of computer simulations. For a number of temperatures, NPT simulations were performed for the solid phase leading to the determination of the free energy of the solid at a reference density. Using the equation of state and free energies of the isotropic and nematic phases available in the existing literature the fluid-solid equilibrium was calculated for the temperatures selected. Taking these fluid-solid equilibrium results as the starting points, the fluid-solid equilibrium curve was determined for a wide range of temperatures using Gibbs-Duhem integration. At high temperatures the sequence of phases encountered on compression is isotropic to nematic, and then nematic to solid. For reduced temperatures below T=0.85 the sequence is from the isotropic phase directly to the solid state. In view of this we locate the isotropic-nematic-solid triple point at TINS=0.85. The present results suggest that the high-density phase designated smectic B in previous simulations of the model is in fact a molecular solid and not a smectic liquid crystal. It seems that no thermodynamically stable smectic phase appears for the Gay-Berne model with the choice of parameters used in this work. We locate the vapor-isotropic liquid-solid triple point at a temperature TVIS=0.445. Considering that the critical temperatures is Tc=0.473, the Gay-Berne model used in this work presents vapor-liquid separation over a rather narrow range of temperatures. It is suggested that the strong lateral attractive interactions present in the Gay-Berne model stabilizes the layers found in the solid phase. The large stability of the solid phase, particularly at low temperatures, would explain the unexpectedly small liquid range observed in the vapor-liquid region.

Simultaneous determination of cadmium, lead and mercury ions at trace level by magnetic solid phase extraction with Fe@Ag@Dimercaptobenzene coupled to high performance liquid chromatography.

PubMed

Zhou, Qingxiang; Lei, Man; Liu, Yongli; Wu, Yalin; Yuan, Yongyong

2017-12-01

Pollution resulted from heavy metal ions have absorbed much attention, and it is of great importance to develop sensitive and simultaneous determination method for them with common technologies without highly sensitive instruments. We prepared a new and functional core-shell magnetic nano-material, Fe@Ag@dimercaptobenzene (Fe@Ag@DMB), by a one-step method with sodium borohydride as the reducing agent and transmission electron microscopy (TEM) and energy dispersive spectrometer (EDS) were used for characterisation. The mercapto functional groups on the newly synthesised magnetic nanoparticles could interact with Cd 2+ , Pb 2+ , and Hg 2+ ions in water samples and then efficient extraction for Cd 2+ , Pb 2+ , and Hg 2+ ions was achieved. DDTC-Na solution was a good elutent for elution of these ions from Fe@Ag@DMB nanoparticles. Based on these, a sensitive method was developed for simultaneous preconcentration and determination of the aforementioned ions using magnetic Fe@Ag@DMB nanoparticles as the magnetic solid phase extraction adsorbent prior to high performance liquid chromatography coupled with variable wavelength detection. Under the optimal conditions, the detection limits of the three metal ions were in the range of 0.011-0.031μgL -1 , and precisions were below 2.37% (n=6). The proposed method was evaluated with real water samples, and excellent spiked recoveries achieved indicated that the developed method would be a promising tool for monitoring these heavy metal ions in water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

A sensitive method for the determination of Sulfonamides in seawater samples by Solid Phase Extraction and UV-Visible spectrophotometry

NASA Astrophysics Data System (ADS)

Errayess, Sophia Ait; Lahcen, Abdellatif Ait; Idrissi, Laila; Marcoaldi, Caterina; Chiavarini, Salvatore; Amine, Aziz

2017-06-01

The authors have developed a sensitive spectrophotometric method for determination of sulfonamide derivatives such as sulfanilamide (SAA), sulfadiazine (SDZ), sulfacetamide (SCT) sulfamethoxazole (SMX), sulfamerazine (SMR), sulfadimethoxine (SDX), sulfamethiazole (SMT) and Sulfathiazole (STZ). This method is based on the Bratton-Marshall reaction, which involves the diazotization of sulfonamides with sodium nitrite under acidic conditions, followed by coupling with N-(1-naphtyl) ethylenediamine dihydrochloride (NED) to form a pink colored compound. Therefore, the Bratton-Marshall method was modified by optimizing the reaction conditions, which allows us to determine a low concentration range of sulfonamides compared to the reported methods. The limits of detection and quantification obtained were 0.019-0.05 and 0.06-0.16 μg mL- 1, respectively. In comparison with other reported methods using different coupling agents, the proposed method was found to be the most simple and sensitive for sulfonamides determination. In this paper, the modified method was successfully employed for the determination of sulfonamides in drinking water, seawater and pharmaceutical and veterinary formulations. The purpose of this work is to optimize and develop a simple method for extraction and concentration of sulfonamides present as residues in seawater and their quantification with the recommended spectrophotometric method. Solid phase extraction (SPE) of sulfonamides from seawater samples was evaluated using Oasis HLB cartridges (3 mL, 540 mg). The recovery efficiency was investigated in the sulfonamides concentration range comprised between 0.19 and 126 ng mL- 1. The ease of use of this extraction method makes it very useful for routine laboratory work.

Kinetics of steel slag leaching: Batch tests and modeling

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

De Windt, Laurent, E-mail: laurent.dewindt@mines-paristech.fr; Chaurand, Perrine; Rose, Jerome

2011-02-15

Reusing steel slag as an aggregate for road construction requires to characterize the leaching kinetics and metal releases. In this study, basic oxygen furnace (BOF) steel slag were subjected to batch leaching tests at liquid to solid ratios (L/S) of 10 and 100 over 30 days; the leachate chemistry being regularly sampled in time. A geochemical model of the steel slag is developed and validated from experimental data, particularly the evolution with leaching of mineralogical composition of the slag and trace element speciation. Kinetics is necessary for modeling the primary phase leaching, whereas a simple thermodynamic equilibrium approach can bemore » used for secondary phase precipitation. The proposed model simulates the kinetically-controlled dissolution (hydrolysis) of primary phases, the precipitation of secondary phases (C-S-H, hydroxide and spinel), the pH and redox conditions, and the progressive release of major elements as well as the metals Cr and V. Modeling indicates that the dilution effect of the L/S ratio is often coupled to solubility-controlled processes, which are sensitive to both the pH and the redox potential. A sensitivity analysis of kinetic uncertainties on the modeling of element releases is performed.« less

Studies of phase transitions in the aripiprazole solid dosage form.

PubMed

Łaszcz, Marta; Witkowska, Anna

2016-01-05

Studies of the phase transitions in an active substance contained in a solid dosage form are very complicated but essential, especially if an active substance is classified as a BCS Class IV drug. The purpose of this work was the development of sensitive methods for the detection of the phase transitions in the aripiprazole tablets containing initially its form III. Aripiprazole exhibits polymorphism and pseudopolymorphism. Powder diffraction, Raman spectroscopy and differential scanning calorimetry methods were developed for the detection of the polymorphic transition between forms III and I as well as the phase transition of form III into aripiprazole monohydrate in tablets. The study involved the initial 10 mg and 30 mg tablets, as well as those stored in Al/Al blisters, a triplex blister pack and HDPE bottles (with and without desiccant) under accelerated and long term conditions. The polymorphic transition was not observed in the initial and stored tablets but it was visible on the DSC curve of the Abilify(®) 10 mg reference tablets. The formation of the monohydrate was observed in the diffractograms and Raman spectra in the tablets stored under accelerated conditions. The monohydrate phase was not detected in the tablets stored in the Al/Al blisters under long term conditions. The results showed that the Al/Al blisters can be recommended as the packaging of the aripiprazole tablets containing form III. Copyright © 2015 Elsevier B.V. All rights reserved.

Diagnostic criteria for hepatocellular carcinoma ⩽3 cm with hepatocyte-specific contrast-enhanced magnetic resonance imaging.

PubMed

Choi, Sang Hyun; Byun, Jae Ho; Lim, Young-Suk; Yu, Eunsil; Lee, So Jung; Kim, So Yeon; Won, Hyung Jin; Shin, Yong Moon; Kim, Pyo Nyun

2016-05-01

Current diagnostic imaging criteria for hepatocellular carcinoma (HCC) are dedicated to imaging with nonspecific extracellular contrast agents. This study aimed to evaluate diagnostic criteria for HCC ⩽3 cm on magnetic resonance imaging (MRI) with a hepatocyte-specific contrast agent through an inception cohort study. Of 291 patients with chronic liver disease and new nodules of 1-3 cm in diameter at surveillance ultrasonography, 295 solid nodules (194 HCCs, 98 benign nodules, and three other malignancies) in 198 patients with a confirmed final diagnosis or ⩾24 months follow-up were evaluated on gadoxetic acid-enhanced MRI. Through univariate and multivariate logistic regression analyses, various diagnostic criteria were developed by combining significant MRI findings for diagnosing HCC. The diagnostic performance of each criterion was compared with that of the European Association for the Study of the Liver (EASL) criteria. Four MRI findings (arterial-phase hyperintensity, transitional-phase hypointensity, hepatobiliary-phase hypointensity, and rim enhancement) were independently significant for diagnosis of HCC ⩽3 cm. For whole nodules, EASL criteria showed the best performance for diagnosing HCC (sensitivity, 83.5%; specificity, 81.2%). For nodules ⩽2 cm in diameter, a new criterion (arterial-phase hyperintensity and hepatobiliary-phase hypointensity) showed a significantly higher sensitivity than that of the EASL criteria (83.0% vs. 74.5%, p=0.008), without a significantly different specificity (76.7% vs. 81.1%, p=0.125). EASL criteria exhibit the best diagnostic performance for HCC ⩽3 cm on hepatocyte-specific contrast-enhanced MRI. A newly identified criterion (arterial-phase hyperintensity and hepatobiliary-phase hypointensity) may increase the diagnostic sensitivity of small (⩽2 cm) HCC. Copyright © 2016 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

Apparatus and method for noninvasive particle detection using doppler spectroscopy

DOEpatents

Sinha, Dipen N.

2016-05-31

An apparatus and method for noninvasively detecting the presence of solid particulate matter suspended in a fluid flowing through a pipe or an oil and gas wellbore are described. Fluid flowing through a conduit containing the particulate solids is exposed to a fixed frequency (>1 MHz) of ultrasonic vibrations from a transducer attached to the outside of the pipe. The returning Doppler frequency shifted signal derived from the scattering of sound from the moving solid particles is detected by an adjacent transducer. The transmitted signal and the Doppler signal are combined to provide sensitive particulate detection. The magnitude of the signal and the Doppler frequency shift are used to determine the particle size distribution and the velocity of the particles. Measurement of the phase shift between the applied frequency and the detected Doppler shifted may be used to determine the direction of motion of the particles.

Development and validation of a high-performance liquid chromatography method for determination of lisinopril in human plasma by magnetic solid-phase extraction and pre-column derivatization.

PubMed

Rastkari, Noushin; Ahmadkhaniha, Reza

2018-03-01

A sensitive, reliable and simple HPLC method was developed for the determination of lisinopril in human plasma. The method consists of extraction and clean-up steps based on magnetic solid-phase extraction and pre-column derivatization with a fluorescent reagent. The mobile phase consisted of a mixture of methanol-sodium dihydrogen phosphate (pH 3.0; 0.005 m; 75:25, v/v). The flow rate was set at 0.7 mL/min. Fluorescence detection was performed at 470nm excitation and 530nm emission wavelengths. Total chromatography run time was 5 min. The average extraction recovery of lisinopril and fluvoxamine (internal standard) was ≥82.8%. The limits of detection and quantification were determined as 1 and 3 ng/mL respectively. The method exhibited a linear calibration line over the concentration range of 3-1000 ng/mL with coefficient of determination (r 2 ) of ≥0.98. The within-run and between-run precisions were satisfactory with values of CV of 1.8-12.8% (accuracy from 99.2 to 94.7%) and 2.4-13.7% (accuracy from 99.5 to 92.2%), respectively. These developments led to considerable improvement in method sensitivity and reliability. The method was validated according to the US Food and Drug Administration guidelines. Therefore, it can be considered as a suitable method for determination of lisinopril in plasma samples. Copyright © 2017 John Wiley & Sons, Ltd.

Dispersive solid-phase extraction based on oleic acid-coated magnetic nanoparticles followed by gas chromatography-mass spectrometry for UV-filter determination in water samples.

PubMed

Román, Iván P; Chisvert, Alberto; Canals, Antonio

2011-05-06

A sensitive analytical method to concentrate and determine extensively used UV filters in cosmetic products at (ultra)trace levels in water samples is presented. The method is based on a sample treatment using dispersive solid-phase extraction (dSPE) with laboratory-made chemisorbed oleic acid-coated cobalt ferrite (CoFe(2)O(4)@oleic acid) magnetic nanoparticles (MNPs) as optimized sorbent for the target analytes. The variables involved in dSPE were studied and optimized in terms of sensitivity, and the optimum conditions were: mass of sorbent, 100mg; donor phase volume, 75 mL; pH, 3; and sodium chloride concentration, 30% (w/v). After dSPE, the MNPs were eluted twice with 1.5 mL of hexane, and then the eluates were evaporated to dryness and reconstituted with 50 μL of N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) for the injection into the gas chromatography-mass spectrometry (GC-MS). Under the optimized experimental conditions the method provided good levels of repeatability with relative standard deviations below 16% (n=5, at 100 ng L(-1) level). Limit of detection values ranged between 0.2 and 6.0 ng L(-1), due to the high enrichment factors achieved (i.e., 453-748). Finally, the proposed method was applied to the analysis of water samples of different origin (tap, river and sea). Recovery values showed that the matrices under consideration do not significantly affect the extraction process. Copyright © 2011 Elsevier B.V. All rights reserved.

On-line solid phase extraction coupled to capillary LC-ESI-MS for determination of fluoxetine in human blood plasma.

PubMed

Saber, Amr L

2009-04-15

An instrumental setup including on-line solid phased extraction coupled to capillary liquid chromatography-electrospray ionization-mass spectrometry (SPE-capLC-ESI-MS) has been constructed to improve the sensitivity for quantification of fluoxetine hydrochloride in human plasma. Prior to injection, 0.5 mL of plasma spiked with metronidazole (internal standard) was mixed with ammonium formate buffer for effective chloroform liquid-liquid extraction. The method was validated in the range 5-60 ng mL(-1) fluoxetine, yielding a correlation coefficient of 0.999 (r(2)). The within-assay and between-assay precisions were between (8.5 and 11%) and (6.6 and 7.5%), respectively. The method was used to determine the amount of fluoxetine in a healthy male 14 h after an intake of one capsule of the antidepressant and anorectic Flutin, which contains 20mg fluoxetine per each capsule. Fluoxetine was detected, and the concentration was calculated to 9.0 ng mL(-1) plasma. In the preliminary experiments, conventional LC-UV instrumentation was employed. However, it was found that employing a capillary column with an inner diameter of (0.3mm I.D. x 50 mm, Zorbax C(18)) increased the sensitivity by a factor of approximately 100, when injecting the same mass of analyte. Incorporating an easily automated C(18) reversed phase column switching system with SPE (1.0mm I.D. x 5.0mm, 5 microm) made it possible to inject up to 100 microL of solution, and the total analysis time was 5.5 min.

Combustion modeling of RDX, HMX and GAP with detailed kinetics

NASA Astrophysics Data System (ADS)

Davidson, Jeffrey Edward

A one-dimensional, steady-state numerical model of the combustion of homogeneous solid propellant has been developed. The combustion processes is modeled in three regions: solid, two-phase (liquid and gas) and gas. Conservation of energy and mass equations are solved in the two-phase and gas regions and the eigenvalue of the system (the mass burning rate) is converged by matching the heat flux at the interface of these two regions. The chemical reactions of the system are modeled using a global kinetic mechanism in the two-phase region and an elementary kinetic mechanism in the gas region. The model has been applied to RDX, HMX and GAP. There is very reasonable agreement between experimental data and model predictions for burning rate, temperature sensitivity, surface temperature, adiabatic flame temperature, species concentration profiles and melt-layer thickness. Many of the similarities and differences in the combustion of RDX and HMX are explained from sensitivity analysis results. The combustion characteristics of RDX and HMX are similar because of their similar chemistry. Differences in combustion characteristics arise due to differences in melting temperature, vapor pressure and initial decomposition steps. A reduced mechanism consisting of 18 species and 39 reactions was developed from the Melius-Yetter RDX mechanism (45 species, 232 reactions). This reduced mechanism reproduces most of the predictions of the full mechanism but is 7.5 times faster. Because of lack of concrete thermophysical property data for GAP, the modeling results are preliminary but indicate what type of experimental data is necessary before GAP can be modeled with more certainty.

Body composition in remission of childhood cancer

NASA Astrophysics Data System (ADS)

Tseytlin, G. Ja; Anisimova, A. V.; Godina, E. Z.; Khomyakova, I. A.; Konovalova, M. V.; Nikolaev, D. V.; Rudnev, S. G.; Starunova, O. A.; Vashura, A. Yu

2012-12-01

Here, we describe the results of a cross-sectional bioimpedance study of body composition in 552 Russian children and adolescents aged 7-17 years in remission of various types of cancer (remission time 0-15 years, median 4 years). A sample of 1500 apparently healthy individuals of the same age interval was used for comparison. Our data show high frequency of malnutrition in total cancer patients group depending on type of cancer. 52.7% of patients were malnourished according to phase angle and percentage fat mass z-score with the range between 42.2% in children with solid tumors located outside CNS and 76.8% in children with CNS tumors. The body mass index failed to identify the proportion of patients with malnutrition and showed diagnostic sensitivity 50.6% for obesity on the basis of high percentage body fat and even much less so for undernutrition - 13.4% as judged by low phase angle. Our results suggest an advantage of using phase angle as the most sensitive bioimpedance indicator for the assessment of metabolic alterations, associated risks, and the effectiveness of rehabilitation strategies in childhood cancer patients.

Sensitized chemiluminescence of 2-phenyl-4,5-di(2-furyl)-1H-imidazole/K₃Fe(CN)₆/propyl gallate system combining with solid-phase extraction for the determination of propyl gallate in edible oil.

PubMed

Kang, Jing; Han, Lu; Chen, Zhonglin; Shen, Jimin; Nan, Jun; Zhang, Yihua

2014-09-15

In this paper, a novel chemiluminescence (CL) method has been developed for the determination of propyl gallate (PG). The proposed method was based on the enhancing effect of PG on the CL signal of 2-phenyl-4,5-di(2-furyl)-1H-imidazole (PDFI) and K3Fe(CN)6 reaction in an alkaline solution. Under the optimum conditions, the enhanced CL intensity was linearly related to the concentration of PG. The linear range of the calibration curve was 0.05-8 μg/mL, and the corresponding detection limit (3σ) was 0.036 μg/mL. The relative standard deviation for determining 1.0 μg/mL PG was 2.8% (n=11). The proposed method has been successfully applied to the determination of PG in edible oil. The edible oil samples were prepared by the solid-phase extraction (SPE) with a C18 column served as the stationary phase. Furthermore, the possible CL mechanism was also discussed briefly based on the photoluminescence (PL) and CL spectra. Copyright © 2014 Elsevier Ltd. All rights reserved.

Method optimization for non-equilibrium solid phase microextraction sampling of HAPs for GC/MS analysis

NASA Astrophysics Data System (ADS)

Zawadowicz, M. A.; Del Negro, L. A.

2010-12-01

Hazardous air pollutants (HAPs) are usually present in the atmosphere at pptv-level, requiring measurements with high sensitivity and minimal contamination. Commonly used evacuated canister methods require an overhead in space, money and time that often is prohibitive to primarily-undergraduate institutions. This study optimized an analytical method based on solid-phase microextraction (SPME) of ambient gaseous matrix, which is a cost-effective technique of selective VOC extraction, accessible to an unskilled undergraduate. Several approaches to SPME extraction and sample analysis were characterized and several extraction parameters optimized. Extraction time, temperature and laminar air flow velocity around the fiber were optimized to give highest signal and efficiency. Direct, dynamic extraction of benzene from a moving air stream produced better precision (±10%) than sampling of stagnant air collected in a polymeric bag (±24%). Using a low-polarity chromatographic column in place of a standard (5%-Phenyl)-methylpolysiloxane phase decreased the benzene detection limit from 2 ppbv to 100 pptv. The developed method is simple and fast, requiring 15-20 minutes per extraction and analysis. It will be field-validated and used as a field laboratory component of various undergraduate Chemistry and Environmental Studies courses.

Simultaneous analysis of carotenoids and tocopherols in botanical species using one step solid-liquid extraction followed by high performance liquid chromatography.

PubMed

Valdivielso, Izaskun; Bustamante, María Ángeles; Ruiz de Gordoa, Juan Carlos; Nájera, Ana Isabel; de Renobales, Mertxe; Barron, Luis Javier R

2015-04-15

Carotenoids and tocopherols from botanical species abundant in Atlantic mountain grasslands were simultaneously extracted using one-step solid-liquid phase. A single n-hexane/2-propanol extract containing both types of compounds was injected twice under two different sets of HPLC conditions to separate the tocopherols by normal-phase chromatography and carotenoids by reverse-phase mode. The method allowed reproducible quantification in plant samples of very low amounts of α-, β-, γ- and δ-tocopherols (LOD from 0.0379 to 0.0720 μg g(-1) DM) and over 15 different xanthophylls and carotene isomers. The simplified one-step extraction without saponification significantly increased the recovery of tocopherols and carotenoids, thereby enabling the determination of α-tocopherol acetate in plant samples. The two different sets of chromatographic analysis provided near baseline separation of individual compounds without interference from other lipid compounds extracted from plants, and a very sensitive and accurate detection of tocopherols and carotenoids. The detection of minor individual components in botanical species from grasslands is nowadays of high interest in searching for biomarkers for foods derived from grazing animals. Copyright © 2014 Elsevier Ltd. All rights reserved.

Application of solid phase microextraction followed by liquid chromatography-mass spectrometry in the determination of antibiotic drugs and their metabolites in human whole blood and tissue samples.

PubMed

Szultka-Mlynska, Malgorzata; Pomastowski, Pawel; Buszewski, Boguslaw

2018-06-01

A sensitive, rapid and specific analytical method using high performance liquid chromatography coupled with mass spectrometry (HPLC-QqQ-MS) was developed to determine selected antibiotic drugs and their metabolites (amoxicillin, cefotaxime, ciprofloxacin, clindamycin and metronidazole; amoxycilloic acid, 4-hydroxyphenyl glycyl amoxicillin, desacetyl cefotaxime, 3-desacetyl cefotaxime lactone, ciprofloxacin N-oxide, N-demethylclindamycin, clindamycin sulfoxide, and hydroxy metronidazole) in human whole blood and vascularized tissue after single oral administration. The samples were prepared by solid phase microextraction with C18 fibers (SPME C18 ) and determined on a GRACE analytical C18 column, Vision HT (50 × 2 mm, 1.5 μm) at the flow rate of 0.4 mL min -1 using water and acetonitrile (containing 0.1% formic acid) as the mobile phase. The proposed method was successfully applied in a pharmacokinetic study of the selected antibiotic drugs and their metabolites in real human samples. Additionally, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI/TOF-MS) was used for identification and qualification analysis of the target compounds. Copyright © 2018 Elsevier B.V. All rights reserved.

Solid phase extraction of magnetic carbon doped Fe3O4 nanoparticles.

PubMed

Yang, Jing; Li, Jia-yuan; Qiao, Jun-qin; Lian, Hong-zhen; Chen, Hong-yuan

2014-01-17

Carbon decorated Fe3O4 nanoparticles (Fe3O4/C) are promising magnetic solid-phase extraction (MSPE) sorbents in environmental and biological analysis. Fe3O4/C based MSPE method shows advantages of easy operation, rapidness, high sensitivity, and environmental friendliness. In this paper, the MSPE mechanism of Fe3O4/C nanoparticles has been comprehensively investigated, for the first time, through the following three efforts: (1) the comparison of extraction efficiency for polycyclic aromatic hydrocarbons (PAHs) between the Fe3O4/C sorbents and activated carbon; (2) the chromatographic retention behaviors of hydrophobic and hydrophilic compounds on Fe3O4/C nanoparticles as stationary phase; (3) related MSPE experiments for several typical compounds such as pyrene, naphthalene, benzene, phenol, resorcinol, anisole and thioanisole. It can be concluded that there are hybrid hydrophobic interaction and hydrogen bonding interaction or dipole-dipole attraction between Fe3O4/C sorbents and analytes. It is the existence of carbon and oxygen-containing functional groups coated on the surface of Fe3O4/C nanoparticles that is responsible for the effective extraction process. Copyright © 2013 Elsevier B.V. All rights reserved.

Tailor Made Synthesis of T-Shaped and π-STACKED Dimers in the Gas Phase: Concept for Efficient Drug Design and Material Synthesis

NASA Astrophysics Data System (ADS)

Kumar, Sumit; Das, Aloke

2013-06-01

Non-covalent interactions play a key role in governing the specific functional structures of biomolecules as well as materials. Thus molecular level understanding of these intermolecular interactions can help in efficient drug design and material synthesis. It has been found from X-ray crystallography that pure hydrocarbon solids (i.e. benzene, hexaflurobenzene) have mostly slanted T-shaped (herringbone) packing arrangement whereas mixed solid hydrocarbon crystals (i.e. solid formed from mixtures of benzene and hexafluorobenzene) exhibit preferentially parallel displaced (PD) π-stacked arrangement. Gas phase spectroscopy of the dimeric complexes of the building blocks of solid pure benzene and mixed benzene-hexafluorobenzene adducts exhibit similar structural motifs observed in the corresponding crystal strcutures. In this talk, I will discuss about the jet-cooled dimeric complexes of indole with hexafluorobenzene and p-xylene in the gas phase using Resonant two photon ionzation and IR-UV double resonance spectroscopy combined with quantum chemistry calculations. In stead of studying benzene...p-xylene and benzene...hexafluorobenzene dimers, we have studied corresponding indole complexes because N-H group is much more sensitive IR probe compared to C-H group. We have observed that indole...hexafluorobenzene dimer has parallel displaced (PD) π-stacked structure whereas indole...p-xylene has slanted T-shaped structure. We have shown here selective switching of dimeric structure from T-shaped to π-stacked by changing the substituent from electron donating (-CH3) to electron withdrawing group (fluorine) in one of the complexing partners. Thus, our results demonstrate that efficient engineering of the non-covalent interactions can lead to efficient drug design and material synthesis.

Precipitation in Al–Mg solid solution prepared by solidification under high pressure

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

Jie, J.C., E-mail: jiejc@dlut.edu.cn; School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001; Wang, H.W.

2014-01-15

The precipitation in Al–Mg solid solution containing 21.6 at.% Mg prepared by solidification under 2 GPa was investigated. The results show that the γ-Al{sub 12}Mg{sub 17} phase is formed and the β′ phase cannot be observed in the solid solution during ageing process. The precipitation of γ and β phases takes place in a non-uniform manner during heating process, i.e. the γ and β phases are first formed in the interdendritic region, which is caused by the inhomogeneous distribution of Mg atoms in the solid solution solidified under high pressure. Peak splitting of X-ray diffraction patterns of Al(Mg) solid solutionmore » appears, and then disappears when the samples are aged at 423 K for different times, due to the non-uniform precipitation in Al–Mg solid solution. The direct transformation from the γ to β phase is observed after ageing at 423 K for 24 h. It is considered that the β phase is formed through a peritectoid reaction of α + γ → β which needs the diffusion of Mg atoms across the interface of α/γ phases. - Highlights: • The γ phase is formed and the β′ phase is be observed in Al(Mg) solid solution. • Peak splitting of XRD pattern of Al(Mg) solid solution appears during aged at 150 °C. • The β phase is formed through a peritectoid reaction of α + γ → β.« less

Sensitive Detection of α-Conotoxin GI in Human Plasma Using a Solid-Phase Extraction Column and LC-MS/MS.

PubMed

Yu, Shuo; Yang, Bo; Yan, Liangping; Dai, Qiuyun

2017-07-28

α-conotoxin GI, a short peptide toxin in the venom of Conus geographus , is composed of 13 amino acids and two disulfide bonds. It is the most toxic component of Conus geographus venom with estimated lethal doses of 0.029-0.038 mg/kg for humans. There is currently no reported analytical method for this toxin. In the present study, a sensitive detection method was developed to quantify GI in human plasma using a solid-phase extraction (SPE) column (polystyrene-divinyl benzene copolymer) combined with liquid chromatography/electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) in the multiple reaction monitoring (MRM) mode. The plasma samples were treated with a protein precipitating solvent (methanol: acetonitrile = 50:50, v / v ). GI in the solvent was efficiently extracted with an SPE column and was further separated by a Grace Alltima HP C 18 (50 × 2.1 mm, 5 μm) column at a flow rate of 0.4 mL/min. Water (with 2% methanol) acetonitrile (with 0.1% acetic acid) was selected as the mobile phase combination used in a linear gradient system. α-Conotoxin GI was analyzed by an API 4000 triple quadrupole mass spectrometer. In the method validation, the linear calibration curve in the range of 2.0 to 300.0 ng/mL had correlation coefficients ( r ) above 0.996. The recovery was 57.6-66.8% for GI and the internal standard. The lower limit of quantification (LLOQ) was 2 ng/mL. The intra- and inter-batch precisions were below 6.31% and 8.61%, respectively, and the accuracies were all within acceptance. GI was stable in a bench-top autosampler through long-term storage and freeze/thaw cycles. Therefore, this method is specific, sensitive and reliable for quantitative analysis of α-conotoxin GI in human plasma.

Sorptive thin film microextraction followed by direct solid state spectrofluorimetry: A simple, rapid and sensitive method for determination of carvedilol in human plasma.

PubMed

Karimi, Shima; Talebpour, Zahra; Adib, Noushin

2016-06-14

A poly acrylate-ethylene glycol (PA-EG) thin film is introduced for the first time as a novel polar sorbent for sorptive extraction method coupled directly to solid-state spectrofluorimetry without the necessity of a desorption step. The structure, polarity, fluorescence property and extraction performance of the developed thin film were investigated systematically. Carvedilol was used as the model analyte to evaluate the proposed method. The entire procedure involved one-step extraction of carvedilol from plasma using PA-EG thin film sorptive phase without protein precipitation. Extraction variables were studied in order to establish the best experimental conditions. Optimum extraction conditions were the followings: stirring speed of 1000 rpm, pH of 6.8, extraction temperature of 60 °C, and extraction time of 60 min. Under optimal conditions, extraction of carvedilol was carried out in spiked human plasma; and the linear range of calibration curve was 15-300 ng mL(-1) with regression coefficient of 0.998. Limit of detection (LOD) for the method was 4.5 ng mL(-1). The intra- and inter-day accuracy and precision of the proposed method were evaluated in plasma sample spiked with three concentration levels of carvedilol; yielding a recovery of 91-112% and relative standard deviation of less than 8%, respectively. The established procedure was successfully applied for quantification of carvedilol in plasma sample of a volunteer patient. The developed PA-EG thin film sorptive phase followed by solid-state spectrofluorimetric method provides a simple, rapid and sensitive approach for the analysis of carvedilol in human plasma. Copyright © 2016 Elsevier B.V. All rights reserved.

Ion-exchange solid-phase extraction combined with liquid chromatography-tandem mass spectrometry for the determination of veterinary drugs in organic fertilizers.

PubMed

Zhao, Zhiyong; Zhang, Yanmei; Xuan, Yanfang; Song, Wei; Si, Wenshuai; Zhao, Zhihui; Rao, Qinxiong

2016-06-01

The analysis of veterinary drugs in organic fertilizers is crucial for an assessment of potential risks to soil microbial communities and human health. We develop a robust and sensitive method to quantitatively determine 19 veterinary drugs (amantadine, sulfonamides and fluoroquinolones) in organic fertilizers. The method involved a simple solid-liquid extraction step using the combination of acetonitrile and McIlvaine buffer as extraction solvent, followed by cleanup with a solid-phase extraction cartridge containing polymeric mixed-mode anion-exchange sorbents. Ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was used to separate and detect target analytes. We particularly focused on the optimization of sample clean-up step: different diluents and dilution factors were tested. The developed method was validated in terms of linearity, recovery, precision, sensitivity and specificity. The recoveries of all the drugs ranged from 70.9% to 112.7% at three concentration levels, with the intra-day and inter-day relative standard deviation lower than 15.7%. The limits of quantification were between 1.0 and 10.0μg/kg for all the drugs. Matrix effect was minimized by matrix-matched calibration curves. The analytical method was successfully applied for the survey of veterinary drugs contamination in 20 compost samples. The results indicated that fluoroquinolones had higher incidence rate and mean concentration levels ranging from 31.9 to 308.7μg/kg compared with other drugs. We expect the method will provide the basis for risk assessment of veterinary drugs in organic fertilizers. Copyright © 2016 Elsevier B.V. All rights reserved.

A fast and sensitive method for the simultaneous analysis of a wide range of per- and polyfluoroalkyl substances in indoor dust using on-line solid phase extraction-ultrahigh performance liquid chromatography-time-of-flight-mass spectrometry.

PubMed

Padilla-Sánchez, Juan Antonio; Haug, Line Småstuen

2016-05-06

A fast and sensitive method for simultaneous determination of 18 traditional and 6 alternative per- and polyfluoroalkyl substances (PFASs) using solid-liquid extraction (SLE), off-line clean-up using activated carbon and on-line solid phase extraction-ultrahigh performance liquid chromatography-time-of-flight-mass spectrometry (on-line SPE-UHPLC-TOF-MS) was developed. The extraction efficiency was studied and recoveries in range the 58-114% were obtained. Extraction and injection volumes were also optimized to 2mL and 400μL, respectively. The method was validated by spiking dust from a vacuum cleaner bag that had been found to contain low levels of the PFASs in focus. Low method detection limits (MDLs) and method quantification limits (MQLs) in the range 0.008-0.846ngg(-1) and 0.027-2.820ngg(-1) were obtained, respectively. For most of the PFASs, the accuracies were between 70 and 125% in the range from 2 to100ngg(-1) dust. Intra-day and inter-day precisions were in general well below 30%. Analysis of a Standard Reference Material (SRM 2585) showed high accordance with results obtained by other laboratories. Finally, the method was applied to seven indoor dust samples, and PFAS concentrations in the range 0.02-132ngg(-1) were found. The highest median concentrations were observed for some of the alternative PFASs, such as 6:2-diPAP (25ngg(-1)), 8:2-diPAP (49ngg(-1)), and PFOPA (23ngg(-1)), illustrating the importance of inclusion of new PFASs in the analytical methods. Copyright © 2016 Elsevier B.V. All rights reserved.

Pleurotus eryngii immobilized Amberlite XAD-16 as a solid-phase biosorbent for preconcentrations of Cd2+ and Co2+ and their determination by ICP-OES.

PubMed

Özdemir, Sadin; Okumuş, Veysi; Kılınç, Ersin; Bilgetekin, Havin; Dündar, Abdurrahman; Ziyadanogˇulları, Berrin

2012-09-15

This article reports a method that is used for the preconcentration and determination of Cd(2+) and Co(2+) in vegetables, using Pleurotus eryngii immobilized Amberlite XAD-16 as a solid-phase biosorbent. The concentrations of metals were determined by inductively coupled plasma-optical spectrometry (ICP-OES). Critical parameters, such as the pH of the solution, flow rate, the amount of biosorbent, type and volume of eluent, and the sample volume, that affect the solid-phase extraction (SPE) procedure were optimized. The optimum extraction conditions were determined as being a pH of 6.0 for Cd(2+) and of 5.0 for Co(2+); a sample flow rate of 2.0 mL min(-1); 200.0mg of biosorbent; and 5.0 mL of 1.0 mol L(-1) HCl as eluent. The capacities of the biosorbent for metal uptake were found to be 11.3 and 9.8 mg g(-1) for Cd(2+) and Co(2+) ions, respectively. Limit of quantitations (LOQs) were found to be 0.67 and 0.82 ng mL(-1), respectively, for Cd(2+) and Co(2+). The linear working curves were observed to be in the linear range from 1.0 to 50.0 ng mL(-1), and possessed high correlation coefficients. The use of the SPE method showed 50.7- and 35.7-fold improvements in the sensitivities of ICP-OES. The developed method was successfully applied to NCS ZC-73014 (a certified reference tea sample). Relative standard deviations (RSD) were lower than 5.0%. The Cd(2+) and Co(2+) concentrations in the different parts (leave, root, stem, and fruit) of purslane, onion, rocket, okra, and aubergine were determined after microwave digestion and solid-phase extraction by P. eryngii immobilized on Amberlite XAD-16. Copyright © 2012 Elsevier B.V. All rights reserved.

Metal organic chemical vapor deposition of 111-v compounds on silicon

DOEpatents

Vernon, Stanley M.

1986-01-01

Expitaxial composite comprising thin films of a Group III-V compound semiconductor such as gallium arsenide (GaAs) or gallium aluminum arsenide (GaAlAs) on single crystal silicon substrates are disclosed. Also disclosed is a process for manufacturing, by chemical deposition from the vapor phase, epitaxial composites as above described, and to semiconductor devices based on such epitaxial composites. The composites have particular utility for use in making light sensitive solid state solar cells.

Detection of anticentromere antibodies using cloned autoantigen CENP-B.

PubMed

Rothfield, N; Whitaker, D; Bordwell, B; Weiner, E; Senecal, J L; Earnshaw, W

1987-12-01

A solid-phase enzyme-linked immunosorbent assay has been established using a cloned fusion protein, CtermCENP-B [beta-gal], as antigen. The fusion protein carries the major epitope of CENP-B, the major centromeric autoantigen. The enzyme-linked immunosorbent assay was more sensitive than immunofluorescence techniques in detecting anticentromere antibodies in patients with scleroderma or Raynaud's disease, and was weakly positive in 3% of normal controls and in 3% of 70 patients with other connective tissue diseases.

Scalability, Scintillation Readout and Charge Drift in a Kilogram Scale Solid Xenon Particle Detector

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

Yoo, J.; Cease, H.; Jaskierny, W. F.

2014-10-23

We report a demonstration of the scalability of optically transparent xenon in the solid phase for use as a particle detector above a kilogram scale. We employ a liquid nitrogen cooled cryostat combined with a xenon purification and chiller system to measure the scintillation light output and electron drift speed from both the solid and liquid phases of xenon. Scintillation light output from sealed radioactive sources is measured by a set of high quantum efficiency photomultiplier tubes suitable for cryogenic applications. We observed a reduced amount of photons in solid phase compared to that in liquid phase. We used amore » conventional time projection chamber system to measure the electron drift time in a kilogram of solid xenon and observed faster electron drift speed in the solid phase xenon compared to that in the liquid phase.« less

Fuel spill identification using solid-phase extraction and solid-phase microextraction. 1. Aviation turbine fuels.

PubMed

Lavine, B K; Brzozowski, D M; Ritter, J; Moores, A J; Mayfield, H T

2001-12-01

The water-soluble fraction of aviation jet fuels is examined using solid-phase extraction and solid-phase microextraction. Gas chromatographic profiles of solid-phase extracts and solid-phase microextracts of the water-soluble fraction of kerosene- and nonkerosene-based jet fuels reveal that each jet fuel possesses a unique profile. Pattern recognition analysis reveals fingerprint patterns within the data characteristic of fuel type. By using a novel genetic algorithm (GA) that emulates human pattern recognition through machine learning, it is possible to identify features characteristic of the chromatographic profile of each fuel class. The pattern recognition GA identifies a set of features that optimize the separation of the fuel classes in a plot of the two largest principal components of the data. Because principal components maximize variance, the bulk of the information encoded by the selected features is primarily about the differences between the fuel classes.

One-pot preparation of magnetic carbon adsorbent derived from pomelo peel for magnetic solid-phase extraction of pollutants in environmental waters.

PubMed

Huang, Youfang; Peng, Jinghe; Huang, Xiaojia

2018-04-20

In this work, magnetic carbon material derived from pomelo peels (MCMPs) was conveniently fabricated utilizing one-pot synthesis method and employed as adsorbent of magnetic solid-phase extraction (MSPE). Several characterized measures including infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometer were used to investigate the morphology, spectroscopic and magnetic properties of prepared adsorbent. Apolar parabens and polar fluoroquinolones (FQs) were used to investigate the extraction performance of MCMPs. Under the optimized extraction conditions, the MCMPs displayed satisfactory extraction performance for target analytes. At the same time, the MCMPs/MSPE was combined with HPLC-DAD for the sensitive determination of parabens and FQs in real-life water samples. Results showed that the limits of detection (S/N = 3) for parabens and FQs were in the ranges of 0.011-0.053 μg/L and 0.012-0.46 μg/L, respectively. The spiked recoveries were in the range of 76.6-116% for parabens and 80.2-114% for FQs with good repeatability (relative standard deviations less than 10%). In comparison to reported methods, the developed MCMPs/MSPE-HPLC-DAD showed some merits including low-cost, simplicity, satisfactory sensitivity and green non-pollution. Copyright © 2018 Elsevier B.V. All rights reserved.

Ionic liquid-assisted multiwalled carbon nanotube-dispersive micro-solid phase extraction for sensitive determination of inorganic As species in garlic samples by electrothermal atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Grijalba, Alexander Castro; Escudero, Leticia B.; Wuilloud, Rodolfo G.

2015-08-01

A highly sensitive dispersive micro-solid phase extraction (D-μ-SPE) method combining an ionic liquid (IL) and multi-walled carbon nanotubes (MWCNTs) for inorganic As species (As(III) and As(V)) species separation and determination in garlic samples by electrothermal atomic absorption spectrometry (ETAAS) was developed. Trihexyl(tetradecil)phosphonium chloride IL was used to form an ion pair with the arsenomolybdate complex obtained by reaction of As(V) with molybdate ion. Afterwards, 1.0 mg of MWCNTs was dispersed for As(V) extraction and the supernatant was separated by centrifugation. MWCNTs were re-dispersed with tetradecyltrimethylammonium bromide surfactant and ultrasound followed by direct injection into the graphite furnace of ETAAS for As determination. Pyrolysis and atomization conditions were carefully studied for complete decomposition of MWCNTs and IL matrices. Under optimum conditions, an extraction efficiency of 100% and a preconcentration factor of 70 were obtained with 5 mL of garlic extract. The detection limit was 7.1 ng L- 1 and the relative standard deviations (RSDs) for six replicate measurements at 5 μg L- 1 of As were 5.4% and 4.8% for As(III) and As(V), respectively. The proposed D-μ-SPE method allowed the efficient separation and determination of inorganic As species in a complex matrix such as garlic extract.

Optimization of a sensitive method for the determination of nitro musk fragrances in waters by solid-phase microextraction and gas chromatography with micro electron capture detection using factorial experimental design.

PubMed

Polo, Maria; Garcia-Jares, Carmen; Llompart, Maria; Cela, Rafael

2007-08-01

A solid-phase microextraction method (SPME) followed by gas chromatography with micro electron capture detection for determining trace levels of nitro musk fragrances in residual waters was optimized. Four nitro musks, musk xylene, musk moskene, musk tibetene and musk ketone, were selected for the optimization of the method. Factors affecting the extraction process were studied using a multivariate approach. Two extraction modes (direct SPME and headspace SPME) were tried at different extraction temperatures using two fiber coatings [Carboxen-polydimethylsiloxane (CAR/PDMS) and polydimethylsiloxane-divinylbenzene (PDMS/DVB)] selected among five commercial tested fibers. Sample agitation and the salting-out effect were also factors studied. The main effects and interactions between the factors were studied for all the target compounds. An extraction temperature of 100 degrees C and sampling the headspace over the sample, using either CAR/PDMS or PDMS/DVB as fiber coatings, were found to be the experimental conditions that led to a more effective extraction. High sensitivity, with detection limits in the low nanogram per liter range, and good linearity and repeatability were achieved for all nitro musks. Since the method proposed performed well for real samples, it was applied to different water samples, including wastewater and sewage, in which some of the target compounds (musk xylene and musk ketone) were detected and quantified.

Determination of polychlorinated biphenyls in transformer oil using various adsorbents for solid phase extraction.

PubMed

Na, Yun-Cheol; Kim, Kang-Jin; Hong, Jongki; Seo, Jung-Ju

2008-08-01

Various adsorbents for a solid phase extraction (SPE) method were used to study their ability to separate PCBs from transformer oil to rapidly determine their sub-ppm concentration in the transformer oil. Approximately 90% of the transformer oil could be removed from the PCBs by using a hydrophilic-lipophilic balanced copolymer (HLB) adsorbent, but the recovery of deca-chlorobiphenyl (deca-CB) used as a surrogate was only 24.5% due to lose during this cleanup process. The use of a silica adsorbent gave good results with 89.9% recovery of the deca-CB. The recovery of Aroclor 1242 and 1260 were 95.4 and 90.3% on silica, and 98.9 and 83.5% on HLB, respectively. Acid treatment was an essential step in removing the ambiguous interference peaks to help identify the PCBs. A decreased sensitivity of the electron capture detection (ECD) for PCBs was observed due to the presence of the remaining trace oil after the workup procedure. This loss in sensitivity was allowed for by using tetrachloroxylene as an internal standard, and this was found to be reliable for the criteria of quality control by employing an experiment in which LCS was spiked with 2mg/l of Aroclor 1260 and analyzed each day over a 25 day period. The MDL for the analytical method established in this study is 0.05 mg/l.

Field method for the determination of hexavalent chromium by ultrasonication and strong anion-exchange solid-phase extraction.

PubMed

Wang, J; Ashley, K; Marlow, D; England, E C; Carlton, G

1999-03-01

A simple, fast, sensitive, and economical field method was developed and evaluated for the determination of hexavalent chromium (CrVI) in environmental and workplace air samples. By means of ultrasonic extraction in combination with a strong anion-exchange solid-phase extraction (SAE-SPE) technique, the filtration, isolation, and determination of CrVI in the presence of trivalent chromium (CrIII) and potential interferents was achieved. The method entails (1) ultrasonication in basic ammonium buffer solution to extract CrVI from environmental matrixes; (2) SAE-SPE to separate CrVI from CrIII and interferences; (3) elution/acidification of the eluate; (4) complexation of chromium with 1,5-diphenylcarbazide; and (5) spectrophotometric determination of the colored chromium-diphenylcarbazone complex. Several critical parameters were optimized in order to effect the extraction of both soluble (K2CrO4) and insoluble (PbCrO4) forms of CrVI without inducing CrIII oxidation or CrVI reduction. The method allowed for the dissolution and purification of CrVI from environmental and workplace air sample matrixes for up to 24 samples simultaneously in less than 90 min (including ultrasonication). The results demonstrated that the method was simple, fast, quantitative, and sufficiently sensitive for the determination of occupational exposures of CrVI. The method is applicable for on-site monitoring of CrVI in environmental and industrial hygiene samples.

Selection of antigenic markers on a GFP-C{kappa} fusion scaffold with high sensitivity by eukaryotic ribosome display

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

Yang Yongmin; IgE Therapeutics, Inc., San Diego, CA 92121-2233; Barankiewicz, Teresa J.

2007-07-27

Ribosome display is a cell-free system permitting gene selection through the physical association of genetic material (mRNA) and its phenotypic (protein) product. While often used to select single-chain antibodies from large libraries by panning against immobilized antigens, we have adapted ribosome display for use in the 'reverse' format in order to select high affinity antigenic determinants against solid-phase antibody. To create an antigenic scaffold, DNA encoding green fluorescent protein (GFP) was fused to a light chain constant domain (C{kappa}) with stop codon deleted, and with 5' signals (T7 promoter, Kozak) enabling coupled transcription/translation in a eukaryotic cell-free system. Epitopes onmore » either GFP (5') or C{kappa} (3') were selected by anti-GFP or anti-C{kappa} antibodies, respectively, coupled to magnetic beads. After selection, mRNA was amplified directly from protein-ribosome-mRNA (PRM) complexes by in situ PCR followed by internal amplification and reassembly PCR. As little as 10 fg of the 1 kb DNA construct, i.e. approximately 7500 molecules, could be recovered following a single round of interaction with solid-phase anti-GFP antibody. This platform is highly specific and sensitive for the antigen-antibody interaction and may permit selection and reshaping of high affinity antigenic variants of scaffold proteins.« less

Photoelectric characterization of fabricated dye-sensitized solar cell using dye extracted from red Siahkooti fruit as natural sensitizer.

PubMed

Mozaffari, Sayed Ahmad; Saeidi, Mahsa; Rahmanian, Reza

2015-05-05

Natural dye extracted from Siahkooti fruit with/without purification by solid phase extraction (SPE) technique was used in the fabrication of DSSC as natural sensitizer. The UV-Vis absorption spectroscopy and Fourier transform infrared (FTIR) were employed to indicate the presence of anthocyanins in the fruit of red Siahkooti. The photoelectrochemical performance and the efficiency of assembled DSSC using Siahkooti fruit dye extract were evaluated and efficiency enhancement was obtained by a preliminary purification of extracted dye. The efficiency and fill factor of the DSSC using purified Siahkooti fruit dye were 0.32% and 0.73%, respectively. The results successfully showed that the DSSC, using Siahkooti fruit extract as a dye sensitizer, is useful for the preparation of environmentally friendly, low-cost, renewable and clean sources of energy. Copyright © 2015 Elsevier B.V. All rights reserved.

Heterogeneous to homogeneous melting transition visualized with ultrafast electron diffraction

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

None

The ultrafast laser excitation of matters leads to non-equilibrium states with complex solid-liquid phase transition dynamics. We used electron diffraction at mega-electronvolt energies to visualize the ultrafast melting of gold on the atomic scale length. For energy densities approaching the irreversible melting regime, we first observed heterogeneous melting on time scales of 100 ps to 1000 ps, transitioning to homogeneous melting that occurs catastrophically within 10-20 ps at higher energy densities. We showed evidence for the heterogeneous coexistence of solid and liquid. We determined the ion and electron temperature evolution and found superheated conditions. Our results constrain the electron-ion couplingmore » rate, determine the Debye temperature and reveal the melting sensitivity to nucleation seeds.« less

Solid-solid phase change thermal storage application to space-suit battery pack

NASA Astrophysics Data System (ADS)

Son, Chang H.; Morehouse, Jeffrey H.

1989-01-01

High cell temperatures are seen as the primary safety problem in the Li-BCX space battery. The exothermic heat from the chemical reactions could raise the temperature of the lithium electrode above the melting temperature. Also, high temperature causes the cell efficiency to decrease. Solid-solid phase-change materials were used as a thermal storage medium to lower this battery cell temperature by utilizing their phase-change (latent heat storage) characteristics. Solid-solid phase-change materials focused on in this study are neopentyl glycol and pentaglycerine. Because of their favorable phase-change characteristics, these materials appear appropriate for space-suit battery pack use. The results of testing various materials are reported as thermophysical property values, and the space-suit battery operating temperature is discussed in terms of these property results.

Determination of trace metals in drinking water using solid-phase extraction disks and X-ray fluorescence spectrometry.

PubMed

Hou, Xiandeng; Peters, Heather L; Yang, Zheng; Wagner, Karl A; Batchelor, James D; Daniel, Meredith M; Jones, Bradley T

2003-03-01

A convenient method is described for monitoring Cd, Ni, Cu, and Pb at trace levels in drinking water samples. These metals are preconcentrated on a chelating solid-phase extraction disk and then determined by X-ray fluorescence spectrometry. The method tolerates a wide pH range (pH 6-14) and a large amount of alkaline and alkaline earth elements. The preconcentration factor is well over 1600, assuming a 1 L water sample volume. The limits of detection for Cd, Ni, Cu, and Pb are 3.8, 0.6, 0.4, and 0.3 ng/mL, respectively. These are well below the federal maximum contaminant level values, which are 5, 100, 1300, and 15 ng/mL, respectively. The proposed method has many advantages including ease of operation, multielement capability, nondestructiveness, high sensitivity, and relative cost efficiency. The solid-phase extraction step can be conducted in the field and then the disks can be mailed to a laboratory for the analysis, eliminating the cost of transporting large volumes of water samples. Furthermore, the color of the used extraction disk provides an initial estimate of the degree of contamination for some transition metals (for example, Ni and Cu). Thus, the overall cost for analysis of metals in drinking water can be minimized by implementing the method, and small water supply companies with limited budgets will be better able to comply with the Safe Drinking Water Act.

Selective capture and rapid identification of Panax notoginseng metabolites in rat faeces by the integration of magnetic molecularly imprinted polymers and high-performance liquid chromatography coupled with orbitrap mass spectrometry.

PubMed

Cai, Qizhi; Yang, Zaiyue; Chen, Ning; Zhou, Xuemin; Hong, Junli

2016-07-15

In the present work, an advanced pretreatment method magnetic molecular imprinted polymers-dispersive solid phase extraction (MMIPs-DSPE) combined with the high sensitivity LTQ-Orbitrap mass spectrometry was applied to the complicated metabolites analysis of Traditional Chinese Medicines (TCMs) in complex matrices. The ginsenoside Rb1 magnetic molecular imprinted polymers (Rb1-MMIPs) were successfully synthesized for specific recognition and selective enrichment of Panax notoginseng saponin metabolites in rat faeces. The polymers were prepared by using Fe3O4@SiO2 as the supporting material, APTES as the functional monomer and TEOS as the cross-linker. The Rb1-MMIPs showed quick separation (10.8 emu/g), large adsorption capacity (636μmol/g), high selectivity and fast binding kinetics (25min). Dispersion solid-phase extraction using Rb1-MMIPs (Rb1-MMIPs-DSPE) integrated with LTQ-Orbitrap MS was applied to fish out and identify saponin metabolites from rat faeces, and totally 58 related compounds were detected within 20min, including 26 PPD-group and 32 PPT-group notoginsenoside metabolites. Parallel tests showed that Rb1-MMIPs-DSPE obtained the lowest matrix effects of 0.98-14.84% and captured the largest number of structural analogues compared with traditional pretreatment methods organic solvent extraction (OSE) and solid phase extraction (SPE). Copyright © 2016 Elsevier B.V. All rights reserved.

Inorganic-organic hybrid coating material for the online in-tube solid-phase microextraction of monohydroxy polycyclic aromatic hydrocarbons in urine.

PubMed

Wang, ShuLing; Xu, Hui

2016-12-01

An inorganic-organic hybrid nanocomposite (zinc oxide/polypyrrole) that represents a novel kind of coating for in-tube solid-phase microextraction is reported. The composite coating was prepared by a facile electrochemical polymerization strategy on the inner surface of a stainless-steel tube. Based on the coated tube, a novel online in-tube solid-phase microextraction with liquid chromatography and mass spectrometry method was developed and applied for the extraction of three monohydroxy polycyclic aromatic hydrocarbons in human urine. The coating displayed good extraction ability toward monohydroxy polycyclic aromatic hydrocarbons. In addition, long lifespan, excellent stability, and good compression resistance were also obtained for the coating. The experimental conditions affecting the extraction were optimized systematically. Under the optimal conditions, the limits of detection and quantification were in the range of 0.039-0.050 and 0.130-0.167 ng/mL, respectively. Good linearity (0.2-100 ng/mL) was obtained with correlation coefficients larger than 0.9967. The repeatability, expressed as relative standard deviation, ranged between 2.5% and 9.4%. The method offered the advantage of process simplicity, rapidity, automation, and sensitivity in the analysis of human urinary monohydroxy polycyclic aromatic hydrocarbons in two different cities of Hubei province. An acceptable recovery of monohydroxy polycyclic aromatic hydrocarbons (64-122%) represented the additional attractive features of the method in real urine analysis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of type A trichothecenes in coix seed by magnetic solid-phase extraction based on magnetic multi-walled carbon nanotubes coupled with ultra-high performance liquid chromatography-tandem mass spectrometry.

PubMed

Dong, Maofeng; Si, Wenshuai; Wang, Weimin; Bai, Bing; Nie, Dongxia; Song, Weiguo; Zhao, Zhihui; Guo, Yirong; Han, Zheng

2016-09-01

Magnetic solid-phase extraction (m-SPE) is a promising sample preparation approach due to its convenience, speed, and simplicity. For the first time, a rapid and reliable m-SPE approach using magnetic multi-walled carbon nanotubes (m-MWCNTs) as the adsorbent was proposed for purification of type A trichothecenes including T-2 toxins (T2), HT-2 toxins (HT-2), diacetoxyscirpenol (DAS), and neosolaniol (NEO) in coix seed. The m-MWCNTs were synthesized by assembling the magnetic nanoparticles (Fe3O4) with MWCNTs by sonication through an aggregation wrap mechanism, and characterized by transmission electron microscope. Several key parameters affecting the performance of the procedure were extensively investigated including extraction solutions, desorption solvents, and m-MWCNT amounts. Under the optimal sample preparation conditions followed by analysis with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), high sensitivity (limit of quantification in the range of 0.3-1.5 μg kg(-1)), good linearity (R (2) > 0.99), satisfactory recovery (73.6-90.6 %), and acceptable precision (≤2.5 %) were obtained. The analytical performance of the developed method has also been successfully evaluated in real coix seed samples. Graphical Abstract Flow chart of determination of type A trichothecenes in coix seed by magnetic solid-phase extraction coupled with ultra-high performance liquid chromatography-tandem mass spectrometry.

An accessible protocol for solid-phase extraction of N-linked glycopeptides through reductive amination by amine-functionalized magnetic nanoparticles.

PubMed

Zhang, Ying; Kuang, Min; Zhang, Lijuan; Yang, Pengyuan; Lu, Haojie

2013-06-04

In light of the significance of glycosylation for wealthy biological events, it is important to prefractionate glycoproteins/glycopeptides from complex biological samples. Herein, we reported a novel protocol of solid-phase extraction of glycopeptides through a reductive amination reaction by employing the easily accessible 3-aminopropyltriethoxysilane (APTES)-functionalized magnetic nanoparticles. The amino groups from APTES, which were assembled onto the surface of the nanoparticles through a one-step silanization reaction, could conjugate with the aldehydes from oxidized glycopeptides and, therefore, completed the extraction. To the best of our knowledge, this is the first example of applying the reductive amination reaction into the isolation of glycopeptides. Due to the elimination of the desalting step, the detection limit of glycopeptides was improved by 2 orders of magnitude, compared to the traditional hydrazide chemistry-based solid phase extraction, while the extraction time was shortened to 4 h, suggesting the high sensitivity, specificity, and efficiency for the extraction of N-linked glycopeptides by this method. In the meantime, high selectivity toward glycoproteins was also observed in the separation of Ribonuclease B from the mixtures contaminated with bovine serum albumin. What's more, this technique required significantly less sample volume, as demonstrated in the successful mapping of glycosylation of human colorectal cancer serum with the sample volume as little as 5 μL. Because of all these attractive features, we believe that the innovative protocol proposed here will shed new light on the research of glycosylation profiling.

Preparation of acryloyl β-cyclodextrin-silica hybrid monolithic column and its application in pipette tip solid-phase extraction and HPLC analysis of methyl parathion and fenthion.

PubMed

Chen, Ling; Dang, Xueping; Ai, Youhong; Chen, Huaixia

2018-05-07

An acryloyl β-cyclodextrin-silica hybrid monolithic column for pipette tip solid-phase extraction and high-performance liquid chromatography determination of methyl parathion and fenthion have been prepared through a sol-gel polymerization method. The synthesis conditions, including the volume of cross-linker and the ratio of inorganic solution to organic solution, were optimized. The prepared monolithic column was characterized by thermogravimetric analysis, scanning electron microscopy and Fourier transform infrared spectroscopy. The eluent type, volume and flow rate, sample volume, flow rate, acidity and ionic strength were optimized in detail. Under the optimized conditions, a simple and sensitive pipette tip solid-phase extraction with high-performance liquid chromatography method was developed for the determination of methyl parathion and fenthion in lettuce. The method yielded a linear calibration curve in the concentration ranges of 15-400 μg/kg for methyl parathion and 20-400 μg/kg for fenthion with correlation coefficients of above 0.9957. The limits of detection were 4.5 μg/kg for methyl parathion and 6.0 μg/kg for fenthion, respectively. The recoveries of methyl parathion and fenthion spiked in lettuce ranged from 96.0 to 104.2% with relative standard deviations less than 8.4%. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Lipid phase behavior studied with a quartz crystal microbalance: A technique for biophysical studies with applications in screening

NASA Astrophysics Data System (ADS)

Peschel, Astrid; Langhoff, Arne; Uhl, Eva; Dathathreyan, Aruna; Haindl, Susanne; Johannsmann, Diethelm; Reviakine, Ilya

2016-11-01

Quartz crystal microbalance (QCM) is emerging as a versatile tool for studying lipid phase behavior. The technique is attractive for fundamental biophysical studies as well applications because of its simplicity, flexibility, and ability to work with very small amounts of material crucial for biomedical studies. Further progress hinges on the understanding of the mechanism, by which a surface-acoustic technique such as QCM, senses lipid phase changes. Here, we use a custom-built instrument with improved sensitivity to investigate phase behavior in solid-supported lipid systems of different geometries (adsorbed liposomes and bilayers). We show that we can detect a model anesthetic (ethanol) through its effect on the lipid phase behavior. Further, through the analysis of the overtone dependence of the phase transition parameters, we show that hydrodynamic effects are important in the case of adsorbed liposomes, and viscoelasticity is significant in supported bilayers, while layer thickness changes make up the strongest contribution in both systems.

Synthesis of a Novel Energetic Heterocyclic Oxidizer with Higher Energy and Lower Sensitivity (Phase 2) Final Report CRADA No. TC02125.0

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

Pagoria, P. F.; Racoveanu, A.

2017-09-08

This project was a continuation of work originally performed under a Phase 1 of the Small Business Technology Transfer (STIR). The success of the Phase 1 led to the award of a Phase 2 of the STIR. In Phase 1 of the STIR, the target energetic compound, 3,4-bis(4-nitro-l,2,5- oxadiazol-3yl)-1,2,5-oxadiazole-l-oxide (DNTF), was synthesized at the 5g scale and small-scale safety tests were performed. DNTF showed promising performance· and safety properties. DNTF was shown to be relatively insensitive while performing better than the current industry standard, H1vIX, in solid propellant formulations. Because of the successful research and development project involving PSI, LLNLmore » and Aerojet in Phase I of the STIR, the sponsors wanted to obtain larger quantities of DNTF for further testing.« less

Energy and Resource Saving of Steelmaking Process: Utilization of Innovative Multi-phase Flux During Dephosphorization Process

NASA Astrophysics Data System (ADS)

Matsuura, Hiroyuki; Hamano, Tasuku; Zhong, Ming; Gao, Xu; Yang, Xiao; Tsukihashi, Fumitaka

2014-09-01

An increase in the utilization efficiency of CaO, one of the major fluxing agents used in various steelmaking processes, is required to reduce the amount of discharged slag and energy consumption of the process. The authors have intensively focused on the development of innovative dephosphorization process by using so called "multi-phase flux" composed of solid and liquid phases. This article summarizes the research on the above topic done by the authors, in which the formation mechanisms of P2O5-containing phase during CaO or 2CaO·SiO2 dissolution into molten slag, the phase relationship between solid and liquid phases at equilibrium, and thermodynamic properties of P2O5-containing phase have been clarified. The reactions between solid CaO or 2CaO·SiO2 and molten CaO-FeO x -SiO2-P2O5 slag were observed by dipping solid specimen in the synthesized slag at 1573 K or 1673 K. The formation of the CaO-FeO layer and dual-phase layer of solid 2CaO·SiO2 and FeO x -rich liquid phase was observed around the interface from the solid CaO side toward the bulk slag phase side. Condensation of P2O5 into 2CaO·SiO2 phase as 2CaO·SiO2-3CaO·P2O5 solid solution was observed in both cases of CaO and 2CaO·SiO2 as solid specimens. Measurement of the phase relationship for the CaO-FeO x -SiO2-P2O5 system confirmed the condensation of P2O5 in solid phase at low oxygen partial pressure. The thermodynamics of 2CaO·SiO2-3CaO·P2O5 solid solution are to be clarified to quantitatively simulate the dephosphorization process, and the current results are also introduced. Based on the above results, the reduction of CaO consumption, the discharged slag curtailment, and energy-saving effects have been discussed.

Crystallization process

DOEpatents

Adler, Robert J.; Brown, William R.; Auyang, Lun; Liu, Yin-Chang; Cook, W. Jeffrey

1986-01-01

An improved crystallization process is disclosed for separating a crystallizable material and an excluded material which is at least partially excluded from the solid phase of the crystallizable material obtained upon freezing a liquid phase of the materials. The solid phase is more dense than the liquid phase, and it is separated therefrom by relative movement with the formation of a packed bed of solid phase. The packed bed is continuously formed adjacent its lower end and passed from the liquid phase into a countercurrent flow of backwash liquid. The packed bed extends through the level of the backwash liquid to provide a drained bed of solid phase adjacent its upper end which is melted by a condensing vapor.

Feasibility of using microencapsulated phase change materials as filler for improving low temperature performance of rubber sealing materials.

PubMed

Tiwari, Avinash; Shubin, Sergey N; Alcock, Ben; Freidin, Alexander B; Thorkildsen, Brede; Echtermeyer, Andreas T

2017-11-01

The feasibility of a novel composite rubber sealing material to improve sealing under transient cooling (in a so-called blowdown scenario) is investigated here. A composite of hydrogenated nitrile butadiene rubber (HNBR) filled with Micro Encapsulated Phase Change Materials (MEPCM) is described. The fillers contain phase change materials that release heat during the phase transformation from liquid to solid while cooling. This exotherm locally heats the rubber and may improve the function of the seal during a blowdown event. A representative HNBR-MEPCM composite was made and the critical thermal and mechanical properties were obtained by simulating the temperature distribution during a blowdown event. Simulations predict that the MEPCM composites can delay the temperature decrease in a region of the seal during the transient blowdown. A sensitivity analysis of material properties is also presented which highlights possible avenues of improvement of the MEPCMs for sealing applications.

Dramatically different kinetics and mechanism at solid/liquid and solid/gas interfaces for catalytic isopropanol oxidation over size-controlled platinum nanoparticles.

PubMed

Wang, Hailiang; Sapi, Andras; Thompson, Christopher M; Liu, Fudong; Zherebetskyy, Danylo; Krier, James M; Carl, Lindsay M; Cai, Xiaojun; Wang, Lin-Wang; Somorjai, Gabor A

2014-07-23

We synthesize platinum nanoparticles with controlled average sizes of 2, 4, 6, and 8 nm and use them as model catalysts to study isopropanol oxidation to acetone in both the liquid and gas phases at 60 °C. The reaction at the solid/liquid interface is 2 orders of magnitude slower than that at the solid/gas interface, while catalytic activity increases with the size of platinum nanoparticles for both the liquid-phase and gas-phase reactions. The activation energy of the gas-phase reaction decreases with the platinum nanoparticle size and is in general much higher than that of the liquid-phase reaction which is largely insensitive to the size of catalyst nanoparticles. Water substantially promotes isopropanol oxidation in the liquid phase. However, it inhibits the reaction in the gas phase. The kinetic results suggest different mechanisms between the liquid-phase and gas-phase reactions, correlating well with different orientations of IPA species at the solid/liquid interface vs the solid/gas interface as probed by sum frequency generation vibrational spectroscopy under reaction conditions and simulated by computational calculations.

Shock initiation of an ɛ-CL-20-estane formulation

NASA Astrophysics Data System (ADS)

Tarver, C. M.; Simpson, R. L.; Urtiew, P. A.

1996-05-01

The shock sensitivity of a pressed solid explosive formulation, LX-19, containing 95.2% by weight epsilon phase 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (HNIW) and 4.8% Estane binder, was determined using the wedge test and embedded manganin pressure gauge techniques. This formulation was shown to be slightly more sensitive than LX-14, which contains 95.5% HMX and 4.5% Estane binder. The measured pressure histories for LX-19 were very similar to those obtained using several HMX-inert binder formulations. An Ignition and Growth reactive flow model for LX-19 was developed which differed from those for HMX-inert binder formulations only by a 25% higher hot spot growth rate.

Simple and sensitive method for quantification of fluorescent enzymatic mature and senescent crosslinks of collagen in bone hydrolysate using single-column high performance liquid chromatography.

PubMed

Viguet-Carrin, S; Gineyts, E; Bertholon, C; Delmas, P D

2009-01-01

A rapid high performance liquid chromatographic method was developed including an internal standard for the measurement of mature and senescent crosslinks concentration in non-demineralized bone hydrolysates. To avoid the demineralization which is a tedious step, we developed a method based on the use of a solid-phase extraction procedure to clean-up the samples. It resulted in sensitive and accurate measurements: the detection limits as low as 0.2 pmol for the pyridimium crosslinks and 0.02 pmol for the pentosidine. The inter- and intra-assay coefficients of variation were as low as 5% and 2%, respectively, for all crosslinks.

UV plasmonic device for sensing ethanol and acetone

NASA Astrophysics Data System (ADS)

Honda, Mitsuhiro; Ichikawa, Yo; Rozhin, Alex G.; Kulinich, Sergei A.

2018-01-01

In the present study, we demonstrate efficient detection of volatile organic vapors with improved sensitivity, exploiting the localized surface plasmon resonance of indium nanograins in the UV range (UV-LSPR). The sensitivity of deep-UV-LSPR measurements toward ethanol was observed to be 0.004 nm/ppm, which is 10 times higher than that of a previously reported visible-LSPR device based on Ag nanoprisms [Sensors 11, 8643 (2011)]. Although practical issues such as improving detection limits are still remaining, the results of the present study suggest that the new approach based on UV-LSPR may open new avenues to the detection of organic molecules in solid, liquid, and gas phases using plasmonic sensors.

Validation of the shake test for detecting freeze damage to adsorbed vaccines.

PubMed

Kartoglu, Umit; Ozgüler, Nejat Kenan; Wolfson, Lara J; Kurzatkowski, Wiesław

2010-08-01

To determine the validity of the shake test for detecting freeze damage in aluminium-based, adsorbed, freeze-sensitive vaccines. A double-blind crossover design was used to compare the performance of the shake test conducted by trained health-care workers (HCWs) with that of phase contrast microscopy as a "gold standard". A total of 475 vials of 8 different types of World Health Organization prequalified freeze-sensitive vaccines from 10 different manufacturers were used. Vaccines were kept at 5 degrees C. Selected numbers of vials from each type were then exposed to -25 degrees C and -2 degrees C for 24-hour periods. There was complete concordance between HCWs and phase-contrast microscopy in identifying freeze-damaged vials and non-frozen samples. Non-frozen samples showed a fine-grain structure under phase contrast microscopy, but freeze-damaged samples showed large conglomerates of massed precipitates with amorphous, crystalline, solid and needle-like structures. Particles in the non-frozen samples measured from 1 microm (vaccines against diphtheria-tetanus-pertussis; Haemophilus influenzae type b; hepatitis B; diphtheria-tetanus-pertussis-hepatitis B) to 20 microm (diphtheria and tetanus vaccines, alone or in combination). By contrast, aggregates in the freeze-damaged samples measured up to 700 microm (diphtheria-tetanus-pertussis) and 350 microm on average. The shake test had 100% sensitivity, 100% specificity and 100% positive predictive value in this study, which confirms its validity for detecting freeze damage to aluminium-based freeze-sensitive vaccines.

Solidification and solid-state transformation sciences in metals additive manufacturing

DOE PAGES

Kirka, Michael M.; Nandwana, Peeyush; Lee, Yousub; ...

2017-02-11

Additive manufacturing (AM) of metals is rapidly emerging as an established manufacturing process for metal components. Unlike traditional metals fabrication processes, metals fabricated via AM undergo localized thermal cycles during fabrication. As a result, AM presents the opportunity to control the liquid-solid phase transformation, i.e. material texture. But, thermal cycling presents challenges from the standpoint of solid-solid phase transformations. We will discuss the opportunities and challenges in metals AM in the context of texture control and associated solid-solid phase transformations in Ti-6Al-4V and Inconel 718.

Microwave spectroscopic observation of distinct electron solid phases in wide quantum wells

NASA Astrophysics Data System (ADS)

Hatke, A. T.; Liu, Yang; Magill, B. A.; Moon, B. H.; Engel, L. W.; Shayegan, M.; Pfeiffer, L. N.; West, K. W.; Baldwin, K. W.

2014-06-01

In high magnetic fields, two-dimensional electron systems can form a number of phases in which interelectron repulsion plays the central role, since the kinetic energy is frozen out by Landau quantization. These phases include the well-known liquids of the fractional quantum Hall effect, as well as solid phases with broken spatial symmetry and crystalline order. Solids can occur at the low Landau-filling termination of the fractional quantum Hall effect series but also within integer quantum Hall effects. Here we present microwave spectroscopy studies of wide quantum wells that clearly reveal two distinct solid phases, hidden within what in d.c. transport would be the zero diagonal conductivity of an integer quantum-Hall-effect state. Explanation of these solids is not possible with the simple picture of a Wigner solid of ordinary (quasi) electrons or holes.

Extinguishment of a Diffusion Flame Over a PMMA Cylinder by Depressurization in Reduced-Gravity

NASA Technical Reports Server (NTRS)

Goldmeer, Jeffrey Scott

1996-01-01

Extinction of a diffusion flame burning over horizontal PMMA (Polymethyl methacrylate) cylinders in low-gravity was examined experimentally and via numerical simulations. Low-gravity conditions were obtained using the NASA Lewis Research Center's reduced-gravity aircraft. The effects of velocity and pressure on the visible flame were examined. The flammability of the burning solid was examined as a function of pressure and the solid-phase centerline temperature. As the solid temperature increased, the extinction pressure decreased, and with a centerline temperature of 525 K, the flame was sustained to 0.1 atmospheres before extinguishing. The numerical simulation iteratively coupled a two-dimensional quasi-steady, gas-phase model with a transient solid-phase model which included conductive heat transfer and surface regression. This model employed an energy balance at the gas/solid interface that included the energy conducted by the gas-phase to the gas/solid interface, Arrhenius pyrolysis kinetics, surface radiation, and the energy conducted into the solid. The ratio of the solid and gas-phase conductive fluxes Phi was a boundary condition for the gas-phase model at the solid-surface. Initial simulations modeled conditions similar to the low-gravity experiments and predicted low-pressure extinction limits consistent with the experimental limits. Other simulations examined the effects of velocity, depressurization rate and Phi on extinction.

SOLID-LIQUID PHASE TRANSFER CATALYZED SYNTHESIS OF CINNAMYL ACETATE-KINETICS AND ANALYSIS OF FACTORS AFFECTING THE REACTION IN A BATCH REACTOR

EPA Science Inventory

The use of solid-liquid phase transfer catalysis has an advantage of carrying out reaction between two immiscible substrates, one in solid phase and the other in liquid phase, with high selectivity and at relatively low temperatures. In this study we investigated the synthesis ci...

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

Renlund, Anita Mariana; Tappan, Alexander Smith; Miller, Jill C.

The HMX {beta}-{delta} solid-solid phase transition, which occurs as HMX is heated near 170 C, is linked to increased reactivity and sensitivity to initiation. Thermally damaged energetic materials (EMs) containing HMX therefore may present a safety concern. Information about the phase transition is vital to predictive safety models for HMX and HMX-containing EMs. We report work on monitoring the phase transition with real-time Raman spectroscopy aimed towards obtaining a better understanding of physical properties of HMX through the phase transition. HMX samples were confined in a cell of minimal free volume in a displacement-controlled or load-controlled arrangement. The cell wasmore » heated and then cooled at controlled rates while real-time Raman spectroscopic measurements were performed. Raman spectroscopy provides a clear distinction between the phases of HMX because the vibrational transitions of the molecule change with conformational changes associated with the phase transition. Temperature of phase transition versus load data are presented for both the heating and cooling cycles in the load-controlled apparatus, and general trends are discussed. A weak dependence of the temperature of phase transition on load was discovered during the heating cycle, with higher loads causing the phase transition to occur at a higher temperature. This was especially true in the temperature of completion of phase transition data as opposed to the temperature of onset of phase transition data. A stronger dependence on load was observed in the cooling cycle, with higher loads causing the reverse phase transitions to occur at a higher cooling temperature. Also, higher loads tended to cause the phase transition to occur over a longer period of time in the heating cycle and over a shorter period of time in the cooling cycle. All three of the pure HMX phases ({alpha}, {beta} and {delta}) were detected on cooling of the heated samples, either in pure form or as a mixture.« less

Synthesis of nano-scale fast ion conducting cubic Li7La3Zr2O12.

PubMed

Sakamoto, Jeff; Rangasamy, Ezhiylmurugan; Kim, Hyunjoung; Kim, Yunsung; Wolfenstine, Jeff

2013-10-25

A solution-based process was investigated for synthesizing cubic Li7La3Zr2O12 (LLZO), which is known to exhibit the unprecedented combination of fast ionic conductivity, and stability in air and against Li. Sol-gel chemistry was developed to prepare solid metal-oxide networks consisting of 10 nm cross-links that formed the cubic LLZO phase at 600 ° C. Sol-gel LLZO powders were sintered into 96% dense pellets using an induction hot press that applied pressure while heating. After sintering, the average LLZO grain size was 260 nm, which is 13 times smaller compared to LLZO prepared using a solid-state technique. The total ionic conductivity was 0.4 mS cm(-1) at 298 K, which is the same as solid-state synthesized LLZO. Interestingly, despite the same room temperature conductivity, the sol-gel LLZO total activation energy is 0.41 eV, which 1.6 times higher than that observed in solid-state LLZO (0.26 eV). We believe the nano-scale grain boundaries give rise to unique transport phenomena that are more sensitive to temperature when compared to the conventional solid-state LLZO.

Comparison of solid-phase bioassays and ecoscores to evaluate the toxicity of contaminated soils.

PubMed

Lors, Christine; Ponge, Jean-François; Martínez Aldaya, Maite; Damidot, Denis

2010-08-01

Five bioassays (inhibition of lettuce germination and growth, earthworm mortality, inhibition of springtail population growth, avoidance by springtails) were compared, using four coke factory soils contaminated by PAHs and trace elements, before and after biotreatment. For each bioassay, several endpoints were combined in an 'ecoscore', a measure of test sensitivity. Ecoscores pooled over all tested bioassays revealed that most organisms were highly sensitive to the concentration of 3-ring PAHs. When four soils were combined, behavioural tests using the springtail Folsomia candida showed higher ecoscores, i.e. they were most sensitive to soil contamination. However, despite overall higher sensitivity of behavioural tests, which could be used for cheap and rapid assessment of soil toxicity, especially at low levels of contamination, some test endpoints were more sensitive than others, and this may differ from a soil to another, pointing to the need for a battery of bioassays when more itemized results are expected. Copyright 2010 Elsevier Ltd. All rights reserved.

Misalignment sensitivity in an intra-cavity coherently combined crossed-Porro resonator configuration

NASA Astrophysics Data System (ADS)

Alperovich, Z.; Buchinsky, O.; Greenstein, S.; Ishaaya, A. A.

2017-08-01

We investigate the misalignment sensitivity in a crossed-Porro resonator configuration when coherently combining two pulsed multimode Nd:YAG laser channels. To the best of our knowledge, this is the first reported study of this configuration. The configuration is based on a passive intra-cavity interferometric combiner that promotes self-phase locking and coherent combining. Detailed misalignment sensitivity measurements are presented, examining both translation and angular deviations of the end prisms and combiner, and are compared to the results for standard flat end-mirror configurations. The results show that the most sensitive parameter in the crossed-Porro resonator configuration is the angular tuning of the intra-cavity interferometric combiner, which is ~±54 µrad. In comparison, with the flat end mirror configuration, the most sensitive parameter in the resonator is the angular tuning of the output coupler, which is ~±11 µrad. Thus, with the crossed-Porro configuration, we obtain significantly reduced sensitivity. This ability to reduce the misalignment sensitivity in coherently combined solid-state configurations may be beneficial in paving their way into practical use in a variety of demanding applications.

Numerical modelling of biomass combustion: Solid conversion processes in a fixed bed furnace

NASA Astrophysics Data System (ADS)

Karim, Md. Rezwanul; Naser, Jamal

2017-06-01

Increasing demand for energy and rising concerns over global warming has urged the use of renewable energy sources to carry a sustainable development of the world. Bio mass is a renewable energy which has become an important fuel to produce thermal energy or electricity. It is an eco-friendly source of energy as it reduces carbon dioxide emissions. Combustion of solid biomass is a complex phenomenon due to its large varieties and physical structures. Among various systems, fixed bed combustion is the most commonly used technique for thermal conversion of solid biomass. But inadequate knowledge on complex solid conversion processes has limited the development of such combustion system. Numerical modelling of this combustion system has some advantages over experimental analysis. Many important system parameters (e.g. temperature, density, solid fraction) can be estimated inside the entire domain under different working conditions. In this work, a complete numerical model is used for solid conversion processes of biomass combustion in a fixed bed furnace. The combustion system is divided in to solid and gas phase. This model includes several sub models to characterize the solid phase of the combustion with several variables. User defined subroutines are used to introduce solid phase variables in commercial CFD code. Gas phase of combustion is resolved using built-in module of CFD code. Heat transfer model is modified to predict the temperature of solid and gas phases with special radiation heat transfer solution for considering the high absorptivity of the medium. Considering all solid conversion processes the solid phase variables are evaluated. Results obtained are discussed with reference from an experimental burner.

Theory of amorphous ices.

PubMed

Limmer, David T; Chandler, David

2014-07-01

We derive a phase diagram for amorphous solids and liquid supercooled water and explain why the amorphous solids of water exist in several different forms. Application of large-deviation theory allows us to prepare such phases in computer simulations. Along with nonequilibrium transitions between the ergodic liquid and two distinct amorphous solids, we establish coexistence between these two amorphous solids. The phase diagram we predict includes a nonequilibrium triple point where two amorphous phases and the liquid coexist. Whereas the amorphous solids are long-lived and slowly aging glasses, their melting can lead quickly to the formation of crystalline ice. Further, melting of the higher density amorphous solid at low pressures takes place in steps, transitioning to the lower-density glass before accessing a nonequilibrium liquid from which ice coarsens.

Standoff detection of trace amounts of solids by nonlinear Raman spectroscopy using shaped femtosecond pulses

NASA Astrophysics Data System (ADS)

Katz, O.; Natan, A.; Silberberg, Y.; Rosenwaks, S.

2008-04-01

We demonstrate a single-beam, standoff (>10m) detection and identification of various materials including minute amounts of explosives under ambient light conditions. This is obtained by multiplex coherent anti-Stokes Raman scattering spectroscopy (CARS) using a single femtosecond phase-shaped laser pulse. We exploit the strong nonresonant background for amplification of the backscattered resonant CARS signals by employing a homodyne detection scheme. The simple and highly sensitive spectroscopic technique has a potential for hazardous materials standoff detection applications.

Efficient methods for attaching non-radioactive labels to the 5' ends of synthetic oligodeoxyribonucleotides.

PubMed Central

Agrawal, S; Christodoulou, C; Gait, M J

1986-01-01

The syntheses are described of two types of linker molecule useful for the specific attachment of non-radioactive labels such as biotin and fluorophores to the 5' terminus of synthetic oligodeoxyribonucleotides. The linkers are designed such that they can be coupled to the oligonucleotide as a final step in solid-phase synthesis using commercial DNA synthesis machines. Increased sensitivity of biotin detection was possible using an anti-biotin hybridoma/peroxidase detection system. PMID:3748808

Complex-formation-enhanced fluorescence quenching effect for efficient detection of picric acid.

PubMed

Ding, Aixiang; Yang, Longmei; Zhang, Yuyang; Zhang, Gaobin; Kong, Lin; Zhang, Xuanjun; Tian, Yupeng; Tao, Xutang; Yang, Jiaxiang

2014-09-15

Amine-functionalized α-cyanostilbene derivatives (Z)-2-(4-aminophenyl)-3-(4-butoxyphenyl)acrylonitrile (ABA) and (Z)-3-(4-butoxyphenyl)-2-[4-(butylamino)phenyl]acrylonitrile (BBA) were designed for specific recognition of picric acid (PA), an environmental and biological pollutant. The 1:1 host-guest complexes formed between the chemosensors and PA enhanced fluorescence quenching, thus leading to sensitive and selective detection in aqueous media and the solid phase. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Kirka, Michael M.; Nandwana, Peeyush; Lee, Yousub

Additive manufacturing (AM) of metals is rapidly emerging as an established manufacturing process for metal components. Unlike traditional metals fabrication processes, metals fabricated via AM undergo localized thermal cycles during fabrication. As a result, AM presents the opportunity to control the liquid-solid phase transformation, i.e. material texture. But, thermal cycling presents challenges from the standpoint of solid-solid phase transformations. We will discuss the opportunities and challenges in metals AM in the context of texture control and associated solid-solid phase transformations in Ti-6Al-4V and Inconel 718.

Sensitive characterization of polyphenolic antioxidants in Polygonatum odoratum by selective solid phase extraction and high performance liquid chromatography-diode array detector-quadrupole time-of-flight tandem mass spectrometry.

PubMed

Hu, Xin; Zhao, Huading; Shi, Shuyun; Li, Hui; Zhou, Xiaoling; Jiao, Feipeng; Jiang, Xinyu; Peng, Dongming; Chen, Xiaoqin

2015-08-10

The complexity of natural products always leads to the co-elution of interfering compounds with bioactive compounds, which then has a detrimental effect on structural elucidation. Here, a new method, based on selective solid phase extraction combined with 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) spiking and high performance liquid chromatography-diode array detector-quadrupole time-of-flight tandem mass spectrometry (HPLC-DAD-QTOF-MS/MS), is described for sensitive screening, selective extraction and identification of polyphenolic antioxidants in Polygonatum odoratum. First, 25 polyphenolic antioxidants (1-25) were screened by DPPH spiking with HPLC. Second, polydopamine coated Fe3O4 microspheres (Fe3O4@PDA) were prepared to selectively extract target antioxidants with extraction efficiency from 55% to 100% when the amount of Fe3O4@PDA, extraction time, desorption solvent and time were 10mg, 20 min, acetonitrile, and 5 min. Third, 25 antioxidants (10 cinnamides and 15 homoisoflavanones) were identified by HPLC-DAD-QTOF-MS/MS. Furthermore, the DPPH scavenging activities of purified compounds (IC50, 1.6-32.8 μg/mL) validated the method. Among the identified antioxidants, four of them (12, 13, 18 and 19) were new compounds, four of them (2, 4, 8 and 14) were first obtained from family Liliaceae, five of them (1, 3, 5, 7 and 9) were first reported in genus Polygonatum, while one compound (24) was first identified in this species. The results indicated that the proposed method was an efficient and sensitive approach to explore polyphenolic antioxidants from complex natural products. Copyright © 2015 Elsevier B.V. All rights reserved.

On-chip multiplexed solid-phase nucleic acid hybridization assay using spatial profiles of immobilized quantum dots and fluorescence resonance energy transfer.

PubMed

Noor, M Omair; Tavares, Anthony J; Krull, Ulrich J

2013-07-25

A microfluidic based solid-phase assay for the multiplexed detection of nucleic acid hybridization using quantum dot (QD) mediated fluorescence resonance energy transfer (FRET) is described herein. The glass surface of hybrid glass-polydimethylsiloxane (PDMS) microfluidic channels was chemically modified to assemble the biorecognition interface. Multiplexing was demonstrated using a detection system that was comprised of two colors of immobilized semi-conductor QDs and two different oligonucleotide probe sequences. Green-emitting and red-emitting QDs were paired with Cy3 and Alexa Fluor 647 (A647) labeled oligonucleotides, respectively. The QDs served as energy donors for the transduction of dye labeled oligonucleotide targets. The in-channel assembly of the biorecognition interface and the subsequent introduction of oligonucleotide targets was accomplished within minutes using a combination of electroosmotic flow and electrophoretic force. The concurrent quantification of femtomole quantities of two target sequences was possible by measuring the spatial coverage of FRET sensitized emission along the length of the channel. In previous reports, multiplexed QD-FRET hybridization assays that employed a ratiometric method for quantification had challenges associated with lower analytical sensitivity arising from both donor and acceptor dilution that resulted in reduced energy transfer pathways as compared to single-color hybridization assays. Herein, a spatial method for quantification that is based on in-channel QD-FRET profiles provided higher analytical sensitivity in the multiplexed assay format as compared to single-color hybridization assays. The selectivity of the multiplexed hybridization assays was demonstrated by discrimination between a fully-complementary sequence and a 3 base pair sequence at a contrast ratio of 8 to 1. Copyright © 2013 Elsevier B.V. All rights reserved.

Phase relations in the system NaCl-KCl-H2O: V. Thermodynamic-PTX analysis of solid-liquid equilibria at high temperatures and pressures

USGS Publications Warehouse

Sterner, S.M.; Chou, I.-Ming; Downs, R.T.; Pitzer, Kenneth S.

1992-01-01

The Gibbs energies of mixing for NaCl-KCl binary solids and liquids and solid-saturated NaCl-KCl-H2O ternary liquids were modeled using asymmetric Margules treatments. The coefficients of the expressions were calibrated using an extensive array of binary solvus and solidus data, and both binary and ternary liquidus data. Over the PTX range considered, the system exhibits complete liquid miscibility among all three components and extensive solid solution along the anhydrous binary. Solid-liquid and solid-solid phase equilibria were calculated by using the resulting equations and invoking the equality of chemical potentials of NaCl and KCl between appropriate phases at equilibrium. The equations reproduce the ternary liquidus and predict activity coefficients for NaCl and KCl components in the aqueous liquid under solid-saturation conditions between 673 and 1200 K from vapor saturation up to 5 kbar. In the NaCl-KCl anhydrous binary system, the equations describe phase equilibria and predict activity coefficients of the salt components for all stable compositions of solid and liquid phases between room temperature and 1200 K and from 1 bar to 5 kbar. ?? 1992.

[Comparative sensitivity of different solid-phase immunoassays for detecting HBsAg and anti-HCV in blood].

PubMed

León, P; López, J A; Domingo, C J; Echevarría, J M

1992-10-01

The sensitivities of seven methods of enzyme-immunoassay for HBsAg detection, as well as of twelve immunoassays for detecting antibody to HCV, were compared, in an attempt to evaluate the need for an official technical validation of such methods prior to its commercialization in Spain. Significant differences were seen for the sensitivities of these methods, which may influence the proficiency of blood bank screening for HBsAg and anti-HCV for preventing cases of post-transfusional viral hepatitis. As a conclusion, it is recommended to establish legal regulations for pre-marketing validation of such assays in Spain, as well as to take the results obtained in these evaluation studies as the basis for selecting those tests which may be more convenient for screening purposes at the blood banks.

Phase diagram of two-dimensional hard ellipses.

PubMed

Bautista-Carbajal, Gustavo; Odriozola, Gerardo

2014-05-28

We report the phase diagram of two-dimensional hard ellipses as obtained from replica exchange Monte Carlo simulations. The replica exchange is implemented by expanding the isobaric ensemble in pressure. The phase diagram shows four regions: isotropic, nematic, plastic, and solid (letting aside the hexatic phase at the isotropic-plastic two-step transition [E. P. Bernard and W. Krauth, Phys. Rev. Lett. 107, 155704 (2011)]). At low anisotropies, the isotropic fluid turns into a plastic phase which in turn yields a solid for increasing pressure (area fraction). Intermediate anisotropies lead to a single first order transition (isotropic-solid). Finally, large anisotropies yield an isotropic-nematic transition at low pressures and a high-pressure nematic-solid transition. We obtain continuous isotropic-nematic transitions. For the transitions involving quasi-long-range positional ordering, i.e., isotropic-plastic, isotropic-solid, and nematic-solid, we observe bimodal probability density functions. This supports first order transition scenarios.

Binary Solid-Liquid Phase Diagram of Phenol and t-Butanol: An Undergraduate Physical Chemistry Experiment

ERIC Educational Resources Information Center

Xu, Xinhua; Wang, Xiaogang; Wu, Meifen

2014-01-01

The determination of the solid-liquid phase diagram of a binary system is always used as an experiment in the undergraduate physical chemistry laboratory courses. However, most phase diagrams investigated in the lab are simple eutectic ones, despite the fact that complex binary solid-liquid phase diagrams are more common. In this article, the…

Phase transitions of amorphous solid acetone in confined geometry investigated by reflection absorption infrared spectroscopy.

PubMed

Shin, Sunghwan; Kang, Hani; Kim, Jun Soo; Kang, Heon

2014-11-26

We investigated the phase transformations of amorphous solid acetone under confined geometry by preparing acetone films trapped in amorphous solid water (ASW) or CCl4. Reflection absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD) were used to monitor the phase changes of the acetone sample with increasing temperature. An acetone film trapped in ASW shows an abrupt change in the RAIRS features of the acetone vibrational bands during heating from 80 to 100 K, which indicates the transformation of amorphous solid acetone to a molecularly aligned crystalline phase. Further heating of the sample to 140 K produces an isotropic solid phase, and eventually a fluid phase near 157 K, at which the acetone sample is probably trapped in a pressurized, superheated condition inside the ASW matrix. Inside a CCl4 matrix, amorphous solid acetone crystallizes into a different, isotropic structure at ca. 90 K. We propose that the molecularly aligned crystalline phase formed in ASW is created by heterogeneous nucleation at the acetone-water interface, with resultant crystal growth, whereas the isotropic crystalline phase in CCl4 is formed by homogeneous crystal growth starting from the bulk region of the acetone sample.

Jet formation in cerium metal to examine material strength

DOE PAGES

Jensen, B. J.; Cherne, F. J.; Prime, M. B.; ...

2015-11-18

Examining the evolution of material properties at extreme conditions advances our understanding of numerous high-pressure phenomena from natural events like meteorite impacts to general solid mechanics and fluid flow behavior. Some recent advances in synchrotron diagnostics coupled with dynamic compression platforms have introduced new possibilities for examining in-situ, spatially resolved material response with nanosecond time resolution. In this work, we examined jet formation from a Richtmyer-Meshkov instability in cerium initially shocked into a transient, high-pressure phase, and then released to a low-pressure, higher-temperature state. Cerium's rich phase diagram allows us to study the yield stress following a shock induced solid-solidmore » phase transition. X-ray imaging was used to obtain images of jet formation and evolution with 2–3 μm spatial resolution. And from these images, an analytic method was used to estimate the post-shock yield stress, and these results were compared to continuum calculations that incorporated an experimentally validated equation-of-state (EOS) for cerium coupled with a deviatoric strength model. Reasonable agreement was observed between the calculations and the data illustrating the sensitivity of jet formation on the yield stress values. Finally, the data and analysis shown here provide insight into material strength during dynamic loading which is expected to aid in the development of strength aware multi-phase EOS required to predict the response of matter at extreme conditions.« less

Sensitive and selective determination of polycyclic aromatic hydrocarbons in mainstream cigarette smoke using a graphene-coated solid-phase microextraction fiber prior to GC/MS.

PubMed

Wang, Xiaoyu; Wang, Yuan; Qin, Yaqiong; Ding, Li; Chen, Yi; Xie, Fuwei

2015-08-01

A simple method has been developed for the simultaneous determination of 16 polycyclic aromatic hydrocarbons (PAHs) in mainstream cigarette smoke. The procedure is based on employing a homemade graphene-coated solid-phase microextraction (SPME) fiber for extraction prior to GC/MS. In comparison to commercial 100-μm poly(dimethyl siloxane) (PDMS) fiber, the graphene-coated SPME fiber exhibits advantageous cleanup and preconcentration efficiencies. By collecting the particulate phase 5 cigarettes, the LODs and LOQs of 16 target PAHs were 0.02-0.07 and 0.07-0.22 ng/cigarette, respectively, and all of the linear correlation efficiencies were larger than 0.995. The validation results also indicate that the method has good repeatability (RSD between 4.2% and 9.5%) and accuracy (spiked recoveries between 80% and 110%). The developed method was applied to analyze two Kentucky reference cigarettes (1R5F and 3R4F) and six Chinese brands of cigarettes. In addition, the PAH concentrations in the particulate phase of the smoke from the 1R5F Kentucky cigarettes were in good agreement with recently reported results. Due to easy operation and good validation results, this SPME-GC/MS method may be an excellent alternative for trace analysis of PAHs in cigarette smoke. Copyright © 2015 Elsevier B.V. All rights reserved.

Metal-organic framework MIL-101 as sorbent based on double-pumps controlled on-line solid-phase extraction coupled with high-performance liquid chromatography for the determination of flavonoids in environmental water samples.

PubMed

Liu, Yue; Hu, Jia; Li, Yan; Li, Xiao-Shuang; Wang, Zhong-Liang

2016-10-01

A novel method with high sensitivity for the rapid determination of chrysin, apigenin and luteolin in environment water samples was developed by double-pumps controlled on-line solid-phase extraction (SPE) coupled with high-performance liquid chromatography (HPLC). In the developed technique, metal organic framework MIL-101 was synthesized and applied as a sorbent for SPE. The as-synthesized MIL-101 was characterized by scanning electron microscope, X-ray diffraction spectrometry, thermal gravimetric analysis and micropore physisorption analysis. The MIL-101 behaved as a fast kinetics in the adsorption of chrysin, apigenin and luteolin. On-line SPE of chrysin, apigenin and luteolin was processed by loading a sample solution at a flow rate of 1.0 mL/min for 10 min. The extracted analytes were subsequently eluted into a ZORBAX Bonus-RP analytical column (25 cm long × 4.6 mm i.d.) for HPLC separation under isocratic condition with a mobile phase (MeOH: ACN: 0.02 M H 3 PO 4 = 35:35:30) at a flow rate of 1.0 mL/min. Experimental conditions, including ionic strength, sample pH, sample loading rates, sample loading time and desorption analytes time, were further optimized to obtain efficient preconcentration and high-precision determination of the analytes mentioned above. The method achieved the merits of simplicity, rapidity, sensitivity, wide linear range and high sample throughput. The possible mechanism for the adsorption of flavonoids on MIL-101 was proposed. The developed method has been applied to determine trace chrysin, apigenin and luteolin in a variety of environmental water samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fully automated analysis of four tobacco-specific N-nitrosamines in mainstream cigarette smoke using two-dimensional online solid phase extraction combined with liquid chromatography-tandem mass spectrometry.

PubMed

Zhang, Jie; Bai, Ruoshi; Yi, Xiaoli; Yang, Zhendong; Liu, Xingyu; Zhou, Jun; Liang, Wei

2016-01-01

A fully automated method for the detection of four tobacco-specific nitrosamines (TSNAs) in mainstream cigarette smoke (MSS) has been developed. The new developed method is based on two-dimensional online solid-phase extraction-liquid chromatography-tandem mass spectrometry (SPE/LC-MS/MS). The two dimensional SPE was performed in the method utilizing two cartridges with different extraction mechanisms to cleanup disturbances of different polarity to minimize sample matrix effects on each analyte. Chromatographic separation was achieved using a UPLC C18 reversed phase analytical column. Under the optimum online SPE/LC-MS/MS conditions, N'-nitrosonornicotine (NNN), N'-nitrosoanatabine (NAT), N'-nitrosoanabasine (NAB), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) were baseline separated with good peak shapes. This method appears to be the most sensitive method yet reported for determination of TSNAs in mainstream cigarette smoke. The limits of quantification for NNN, NNK, NAT and NAB reached the levels of 6.0, 1.0, 3.0 and 0.6 pg/cig, respectively, which were well below the lowest levels of TSNAs in MSS of current commercial cigarettes. The accuracy of the measurement of four TSNAs was from 92.8 to 107.3%. The relative standard deviations of intra-and inter-day analysis were less than 5.4% and 7.5%, respectively. The main advantages of the method developed are fairly high sensitivity, selectivity and accuracy of results, minimum sample pre-treatment, full automation, and high throughput. As a part of the validation procedure, the developed method was applied to evaluate TSNAs yields for 27 top-selling commercial cigarettes in China. Copyright © 2015 Elsevier B.V. All rights reserved.

Metal-organic frameworks for analytical chemistry: from sample collection to chromatographic separation.

PubMed

Gu, Zhi-Yuan; Yang, Cheng-Xiong; Chang, Na; Yan, Xiu-Ping

2012-05-15

In modern analytical chemistry researchers pursue novel materials to meet analytical challenges such as improvements in sensitivity, selectivity, and detection limit. Metal-organic frameworks (MOFs) are an emerging class of microporous materials, and their unusual properties such as high surface area, good thermal stability, uniform structured nanoscale cavities, and the availability of in-pore functionality and outer-surface modification are attractive for diverse analytical applications. This Account summarizes our research on the analytical applications of MOFs ranging from sampling to chromatographic separation. MOFs have been either directly used or engineered to meet the demands of various analytical applications. Bulk MOFs with microsized crystals are convenient sorbents for direct application to in-field sampling and solid-phase extraction. Quartz tubes packed with MOF-5 have shown excellent stability, adsorption efficiency, and reproducibility for in-field sampling and trapping of atmospheric formaldehyde. The 2D copper(II) isonicotinate packed microcolumn has demonstrated large enhancement factors and good shape- and size-selectivity when applied to on-line solid-phase extraction of polycyclic aromatic hydrocarbons in water samples. We have explored the molecular sieving effect of MOFs for the efficient enrichment of peptides with simultaneous exclusion of proteins from biological fluids. These results show promise for the future of MOFs in peptidomics research. Moreover, nanosized MOFs and engineered thin films of MOFs are promising materials as novel coatings for solid-phase microextraction. We have developed an in situ hydrothermal growth approach to fabricate thin films of MOF-199 on etched stainless steel wire for solid-phase microextraction of volatile benzene homologues with large enhancement factors and wide linearity. Their high thermal stability and easy-to-engineer nanocrystals make MOFs attractive as new stationary phases to fabricate MOF-coated capillaries for high-resolution gas chromatography (GC). We have explored a dynamic coating approach to fabricate a MOF-coated capillary for the GC separation of important raw chemicals and persistent organic pollutants with high resolution and excellent selectivity. We have combined a MOF-coated fiber for solid-phase microextraction with a MOF-coated capillary for GC separation, which provides an effective MOF-based tandem molecular sieve platform for selective microextraction and high-resolution GC separation of target analytes in complex samples. Microsized MOFs with good solvent stability are attractive stationary phases for high-performance liquid chromatography (HPLC). These materials have shown high resolution and good selectivity and reproducibility in both the normal-phase HPLC separation of fullerenes and substituted aromatics on MIL-101 packed columns and position isomers on a MIL-53(Al) packed column and the reversed-phase HPLC separation of a wide range of analytes from nonpolar to polar and acidic to basic solutes. Despite the above achievements, further exploration of MOFs in analytical chemistry is needed. Especially, analytical application-oriented engineering of MOFs is imperative for specific applications.

A sensitive high-pressure liquid chromatography/particle beam/mass spectrometry assay for the determination of all-trans-retinoic acid and 13-cis-retinoic acid in human plasma.

PubMed

Lehman, P A; Franz, T J

1996-03-01

A highly sensitive assay for the measurement of all-trans-retinoic acid (tretinoin) and 13-cis-retinoic acid (isotretinoin) has been developed. Collected plasma samples were protein precipitated with 2-propanol followed by solid phase extraction. The retinoic acids were subsequently derivatized to their pentafluorobenzyl esters followed by separation and isolation by reverse phase high-pressure liquid chromatography. The HPLC eluate was directed to a mass spectrometer via a particle beam interface. Selected ion monitoring (299 m/z) for the retinoic acid's carboxylate anion produced by negative chemical ionization using methane reagent gas achieved minimum detection limits of 25 pg injected. Endogenous blood levels in 19 male and 9 female subjects were measured. It was found that females have significantly more all-trans-retinoic acid than males and that both sexes demonstrate significantly more all-trans-retinoic acid then 13-cis-retinoic acid.

Quasi-molecular bosonic complexes-a pathway to SQUID with controlled sensitivity

NASA Astrophysics Data System (ADS)

Safavi-Naini, Arghavan; Capogrosso-Sansone, Barbara; Kuklov, Anatoly; Penna, Vittorio

2016-02-01

Recent experimental advances in realizing degenerate quantum dipolar gases in optical lattices and the flexibility of experimental setups in attaining various geometries offer the opportunity to explore exotic quantum many-body phases stabilized by anisotropic, long-range dipolar interaction. Moreover, the unprecedented control over the various physical properties of these systems, ranging from the quantum statistics of the particles, to the inter-particle interactions, allow one to engineer novel devices. In this paper, we consider dipolar bosons trapped in a stack of one-dimensional optical lattice layers, previously studied in (Safavi-Naini et al 2014 Phys. Rev. A 90 043604). Building on our prior results, we provide a description of the quantum phases stabilized in this system which include composite superfluids (CSFs), solids, and supercounterfluids, most of which are found to be threshold-less with respect to the dipolar interaction strength. We also demonstrate the effect of enhanced sensitivity to rotations of a SQUID-type device made of two CSF trapped in a ring-shaped optical lattice layer with weak links.

Solid electrolyte-electrode system for an electrochemical cell

DOEpatents

Tuller, Harry L.; Kramer, Steve A.; Spears, Marlene A.

1995-01-01

An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is also provided.

Two-dimensional solid-phase extraction strategy for the selective enrichment of aminoglycosides in milk.

PubMed

Shen, Aijin; Wei, Jie; Yan, Jingyu; Jin, Gaowa; Ding, Junjie; Yang, Bingcheng; Guo, Zhimou; Zhang, Feifang; Liang, Xinmiao

2017-03-01

An orthogonal two-dimensional solid-phase extraction strategy was established for the selective enrichment of three aminoglycosides including spectinomycin, streptomycin, and dihydrostreptomycin in milk. A reversed-phase liquid chromatography material (C 18 ) and a weak cation-exchange material (TGA) were integrated in a single solid-phase extraction cartridge. The feasibility of two-dimensional clean-up procedure that experienced two-step adsorption, two-step rinsing, and two-step elution was systematically investigated. Based on the orthogonality of reversed-phase and weak cation-exchange procedures, the two-dimensional solid-phase extraction strategy could minimize the interference from the hydrophobic matrix existing in traditional reversed-phase solid-phase extraction. In addition, high ionic strength in the extracts could be effectively removed before the second dimension of weak cation-exchange solid-phase extraction. Combined with liquid chromatography and tandem mass spectrometry, the optimized procedure was validated according to the European Union Commission directive 2002/657/EC. A good performance was achieved in terms of linearity, recovery, precision, decision limit, and detection capability in milk. Finally, the optimized two-dimensional clean-up procedure incorporated with liquid chromatography and tandem mass spectrometry was successfully applied to the rapid monitoring of aminoglycoside residues in milk. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transformation toughened ceramics for the heavy duty diesel engine technology program, phase 2

NASA Technical Reports Server (NTRS)

Musikant, S.; Samanta, S. C.; Architetto, P.; Feingold, E.

1985-01-01

The objective of this program is to develop an insulating structural ceramic for application in a heavy duty adiabatic diesel engine. The approach is to employ transformation toughening (TT) by additions of zirconia-hafnia solid solution (ZHSS). The feasibility of using ZHSS as a toughening agent in mullite and alumina has been demonstrated in Phase 1 of this work. Based on Phase 1 results, a decision was made to concentrate the Phase 2 effort on process optimization of the TT mullite. A strong factor in that decision was the low thermal conductivity and high thermal shock resistance of the mullite. Results of the Phase 2 effort indicate that optimum toughening of mullite by additions of ZHSS is difficult to achieve due to apparent sensitivity to morphology. The 48 ksi room temperature modulus-of-rupture (MOR) achieved in selected specimens is approximately 50% of the original strength target. The MOR deteriorated to 34 ksi at 800 C.

Quantitative x-ray phase imaging at the nanoscale by multilayer Laue lenses

PubMed Central

Yan, Hanfei; Chu, Yong S.; Maser, Jörg; Nazaretski, Evgeny; Kim, Jungdae; Kang, Hyon Chol; Lombardo, Jeffrey J.; Chiu, Wilson K. S.

2013-01-01

For scanning x-ray microscopy, many attempts have been made to image the phase contrast based on a concept of the beam being deflected by a specimen, the so-called differential phase contrast imaging (DPC). Despite the successful demonstration in a number of representative cases at moderate spatial resolutions, these methods suffer from various limitations that preclude applications of DPC for ultra-high spatial resolution imaging, where the emerging wave field from the focusing optic tends to be significantly more complicated. In this work, we propose a highly robust and generic approach based on a Fourier-shift fitting process and demonstrate quantitative phase imaging of a solid oxide fuel cell (SOFC) anode by multilayer Laue lenses (MLLs). The high sensitivity of the phase to structural and compositional variations makes our technique extremely powerful in correlating the electrode performance with its buried nanoscale interfacial structures that may be invisible to the absorption and fluorescence contrasts. PMID:23419650

Adsorption of the Three-phase Emulsion on Various Solid Surfaces.

PubMed

Enomoto, Yasutaka; Imai, Yoko; Tajima, Kazuo

2017-07-01

The present study investigates the adsorption of the three-phase emulsion on various solid/water interfaces. Vesicles can be used as emulsifiers in the three-phase emulsions and act as an independent phase unlike the surfactant used in conventional emulsions; therefore, it is expected that the three-phase emulsion formed by the adhesion of vesicles to the oil/water interface will adsorb on various solid/water interfaces. The cationic three-phase emulsion was prepared to encourage emulsion adsorption on negatively charged solid substrates in water. The emulsifier polyoxyethylene-(10) hydrogenated castor oil was rendered cationic by mixing with the surfactant cetyltrimethylammonium bromide and then used to prepare the cationic three-phase emulsion of hexadecane-in-water. Three solid substrates (silicon, glass, and copper) were dipped in the cationic emulsion and the emulsion was found to adsorb on the solid substrates while maintaining its structure. The amount of hexadecane adsorbed on the various surfaces was investigated by gas chromatography and found to increase with increasing hexadecane concentration in the emulsion and eventually plateaued just like molecular adsorption. The maximum surface coverage of the emulsion on the substrates was approximately 80%. However, even the equivalent nonionic three-phase emulsion was found to adsorb on the three solid surfaces. This was attributed to a novel mechanism of irreversible adhesion via the van der Waals attractive force.

Manual Solid-Phase Peptide Synthesis of Metallocene-Peptide Bioconjugates

ERIC Educational Resources Information Center

Kirin, Srecko I.; Noor, Fozia; Metzler-Nolte, Nils; Mier, Walter

2007-01-01

A simple and relatively inexpensive procedure for preparing a biologically active peptide using solid phase peptide synthesis (SPPS) is described. Fourth-year undergraduate students have gained firsthand experience from the solid-phase synthesis techniques and they have become familiar with modern analytical techniques based on the particular…

Effect of solid-meal caloric content on gastric emptying kinetics of solids and liquids.

PubMed

Urbain, J L; Siegel, J A; Mortelmans, L; van Cutsem, E; van den Maegdenbergh, V; de Roo, M

1989-08-01

In this study, we have evaluated the effect of the caloric content of a physiological test meal on the gastric emptying kinetics of solids and liquids. 22 healthy male volunteers were studied in two groups matched for age. After an overnight fast, each volunteer underwent the same test procedure; in the first group (G I), 10 volunteers received a meal consisting of bread, 111In-DTPA water and 1 scrambled egg labeled with 99mTc-labelled sulphur colloid; in the second group (G II) 12 volunteers were given the same meal but with 2 labeled eggs in order to increase the caloric content of the solid phase meal. Simultaneous anterior and posterior images were recorded using a dual-headed gamma camera. Solid and liquid geometric mean data were analyzed to determine the lag phase, the emptying rate and the half-emptying time for both solids and liquids. Solid and liquid gastric half-emptying times were significantly prolonged in G II compared to G I volunteers. For the solid phased, the delay was accounted for by a longer lag phase and a decrease in the equilibrium emptying rate. The emptying rate of the liquid phase was significantly decreased in G II compared to G I. Within each group, no statistically significant difference was observed between solid and liquid emptying rates. We conclude that the caloric content of the solid portion of a meal not only alters the emptying of the solid phase but also affects the emptying of the liquid component of the meal.

Theory of amorphous ices

PubMed Central

Limmer, David T.; Chandler, David

2014-01-01

We derive a phase diagram for amorphous solids and liquid supercooled water and explain why the amorphous solids of water exist in several different forms. Application of large-deviation theory allows us to prepare such phases in computer simulations. Along with nonequilibrium transitions between the ergodic liquid and two distinct amorphous solids, we establish coexistence between these two amorphous solids. The phase diagram we predict includes a nonequilibrium triple point where two amorphous phases and the liquid coexist. Whereas the amorphous solids are long-lived and slowly aging glasses, their melting can lead quickly to the formation of crystalline ice. Further, melting of the higher density amorphous solid at low pressures takes place in steps, transitioning to the lower-density glass before accessing a nonequilibrium liquid from which ice coarsens. PMID:24858957

Electron drift in a large scale solid xenon

DOE PAGES

Yoo, J.; Jaskierny, W. F.

2015-08-21

A study of charge drift in a large scale optically transparent solid xenon is reported. A pulsed high power xenon light source is used to liberate electrons from a photocathode. The drift speeds of the electrons are measured using a 8.7 cm long electrode in both the liquid and solid phase of xenon. In the liquid phase (163 K), the drift speed is 0.193 ± 0.003 cm/μs while the drift speed in the solid phase (157 K) is 0.397 ± 0.006 cm/μs at 900 V/cm over 8.0 cm of uniform electric fields. Furthermore, it is demonstrated that a factor twomore » faster electron drift speed in solid phase xenon compared to that in liquid in a large scale solid xenon.« less

Determination of aflatoxins in food samples by automated on-line in-tube solid-phase microextraction coupled with liquid chromatography-mass spectrometry.

PubMed

Nonaka, Y; Saito, K; Hanioka, N; Narimatsu, S; Kataoka, H

2009-05-15

A simple and sensitive automated method for determination of aflatoxins (B1, B2, G1, and G2) in nuts, cereals, dried fruits, and spices was developed consisting of in-tube solid-phase microextraction (SPME) coupled with liquid chromatography-mass spectrometry (LC-MS). Aflatoxins were separated within 8 min by high-performance liquid chromatography using a Zorbax Eclipse XDB-C8 column with methanol/acetonitrile (60/40, v/v): 5mM ammonium formate (45:55) as the mobile phase. Electrospray ionization conditions in the positive ion mode were optimized for MS detection of aflatoxins. The pseudo-molecular ions [M+H](+) were used to detect aflatoxins in selected ion monitoring (SIM) mode. The optimum in-tube SPME conditions were 25draw/eject cycles of 40 microL of sample using a Supel-Q PLOT capillary column as an extraction device. The extracted aflatoxins were readily desorbed from the capillary by passage of the mobile phase, and no carryover was observed. Using the in-tube SPME LC-MS with SIM method, good linearity of the calibration curve (r>0.9994) was obtained in the concentration range of 0.05-2.0 ng/mL using aflatoxin M1 as an internal standard, and the detection limits (S/N=3) of aflatoxins were 2.1-2.8 pg/mL. The in-tube SPME method showed >23-fold higher sensitivity than the direct injection method (10 microL injection volume). The within-day and between-day precision (relative standard deviations) at the concentration of 1 ng/mL aflatoxin mixture were below 3.3% and 7.7% (n=5), respectively. This method was applied successfully to analysis of food samples without interference peaks. The recoveries of aflatoxins spiked into nuts and cereals were >80%, and the relative standard deviations were <11.2%. Aflatoxins were detected at <10 ng/g in several commercial food samples.

High pressure dielectric studies on the structural and orientational glass.

PubMed

Kaminska, E; Tarnacka, M; Jurkiewicz, K; Kaminski, K; Paluch, M

2016-02-07

High pressure dielectric studies on the H-bonded liquid D-glucose and Orientationally Disordered Crystal (ODIC) 1,6-anhydro-D-glucose (levoglucosan) were carried out. It was shown that in both compounds, the structural relaxation is weakly sensitive to compression. It is well reflected in the low pressure coefficient of the glass transition and orientational glass transition temperatures which is equal to 60 K/GPa for both D-glucose and 1,6-anhydro-D-glucose. Although it should be noted that ∂Tg(0)/∂p evaluated for the latter compound seems to be enormously high with respect to other systems forming ODIC phase. We also found that the shape of the α-loss peak stays constant for the given relaxation time independently on the thermodynamic condition. Consequently, the Time Temperature Pressure (TTP) rule is satisfied. This experimental finding seems to be quite intriguing since the TTP rule was shown to work well in the van der Waals liquids, while in the strongly associating compounds, it is very often violated. We have also demonstrated that the sensitivity of the structural relaxation process to the temperature change measured by the steepness index (mp) drops with pressure. Interestingly, this change is much more significant in the case of D-glucose with respect to levoglucosan, where the fragility changes only slightly with compression. Finally, kinetics of ODIC-crystal phase transition was studied at high compression. It is worth mentioning that in the recent paper, Tombari and Johari [J. Chem. Phys. 142, 104501 (2015)] have shown that ODIC phase in 1,6-anhydro-D-glucose is stable in the wide range of temperatures and there is no tendency to form more ordered phase at ambient pressure. On the other hand, our isochronal measurements performed at varying thermodynamic conditions indicated unquestionably that the application of pressure favors solid (ODIC)-solid (crystal) transition in 1,6-anhydro-D-glucose. This result mimics the impact of pressure on the crystallization of fully disordered supercooled van der Waals liquids.

Grain Floatation During Equiaxed Solidification of an Al-Cu Alloy in a Side-Cooled Cavity: Part II—Numerical Studies

NASA Astrophysics Data System (ADS)

Kumar, Arvind; Walker, Mike J.; Sundarraj, Suresh; Dutta, Pradip

2011-08-01

In this article, a single-phase, one-domain macroscopic model is developed for studying binary alloy solidification with moving equiaxed solid phase, along with the associated transport phenomena. In this model, issues such as thermosolutal convection, motion of solid phase relative to liquid and viscosity variations of the solid-liquid mixture with solid fraction in the mobile zone are taken into account. Using the model, the associated transport phenomena during solidification of Al-Cu alloys in a rectangular cavity are predicted. The results for temperature variation, segregation patterns, and eutectic fraction distribution are compared with data from in-house experiments. The model predictions compare well with the experimental results. To highlight the influence of solid phase movement on convection and final macrosegregation, the results of the current model are also compared with those obtained from the conventional solidification model with stationary solid phase. By including the independent movement of the solid phase into the fluid transport model, better predictions of macrosegregation, microstructure, and even shrinkage locations were obtained. Mechanical property prediction models based on microstructure will benefit from the improved accuracy of this model.

Solid phase pegylation of hemoglobin.

PubMed

Suo, Xiaoyan; Zheng, Chunyang; Yu, Pengzhan; Lu, Xiuling; Ma, Guanghui; Su, Zhiguo

2009-01-01

A solid phase conjugation process was developed for attachment of polyethylene glycol to hemoglobin molecule. Bovine hemoglobin was loaded onto an ion exchange chromatography column and adsorbed by the solid medium. Succinimidyl carbonate mPEG was introduced in the mobile phase after the adsorption. Pegylation took place between the hemoglobin on the solid phase, and the pegylation reagent in the liquid phase. A further elution was carried out to separate the pegylated and the unpegylated protein. Analysis by HPSEC, SDS-PAGE, and MALLS demonstrated that the fractions eluted from the solid phase contained well-defined components. Pegylated hemoglobin with one PEG chain was obtained with the yield of 75%, in comparison to the yield of 30% in the liquid phase pegylation. The P(50) values of the mono-pegylated hemoglobin, prepared with SC-mPEG 5 kDa, 10 kDa and 20 kDa, were 19.97, 20.23 and 20.54 mmHg, which were much closer to the value of red blood cells than that of pegylated hemoglobin prepared with the conventional method.

Mechanism of Formation of Li 7 P 3 S 11 Solid Electrolytes through Liquid Phase Synthesis

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

Wang, Yuxing; Lu, Dongping; Bowden, Mark

Crystalline Li7P3S11 is a promising solid electrolyte for all solid state lithium/lithium ion batteries. A controllable liquid phase synthesis of Li7P3S11 is more desirable compared to conventional mechanochemical synthesis, but recent attempts suffer from reduced ionic conductivities. Here we elucidate the formation mechanism of crystalline Li7P3S11 synthesized in the liquid phase (acetonitrile, or ACN). We conclude that the crystalline Li7P3S11 forms through a two-step reaction: 1) formation of solid Li3PS4∙ACN and amorphous Li2S∙P2S5 phases in the liquid phase; 2) solid-state conversion of the two phases. The implication of this two-step reaction mechanism to the morphology control and the transport propertiesmore » of liquid phase synthesized Li7P3S11 is identified and discussed.« less

Evolution from successive phase transitions to "morphotropic phase boundary" in BaTiO3-based ferroelectrics

NASA Astrophysics Data System (ADS)

Zhou, Chao; Ke, Xiaoqin; Yao, Yonggang; Yang, Sen; Ji, Yuanchao; Liu, Wenfeng; Yang, Yaodong; Zhang, Lixue; Hao, Yanshuang; Ren, Shuai; Zhang, Le; Ren, Xiaobing

2018-04-01

Obtaining superior physical properties for ferroic materials by manipulating the phase transitions is a key concern in solid state physics. Here, we investigated the dielectric permittivity, piezoelectric coefficient d33, storage modulus, and crystal symmetry of (1-x)Ba(Ti0.8Zr0.2)O3-x(Ba1-yCay)TiO3 (BZT-xBCyT) systems to demonstrate the gradual evolution process from successive phase transitions in BaTiO3 to the morphotropic phase boundary (MPB) regime in BZT-xBC0.3T. Furthermore, we analysed with a Landau-type theoretical model to show that the high field-sensitive response (dielectric permittivity) originates from a small polarization anisotropy and low energy barrier at the quadruple point. Together, the intermediate orthorhombic phase regime and the tetragonal-orthorhombic and orthorhombic-rhombohedral phase boundaries constitute the MPB. Our work not only reconciles the arguments regarding whether the structural state around the MPB corresponds to a single-phase regime or a multiple-phase-coexistence regime but also suggests an effective method to design high-performance functional ferroic materials by tailoring the successive phase transitions.

Electropolymerized fluorinated aniline-based fiber for headspace solid-phase microextraction and gas chromatographic determination of benzaldehyde in injectable pharmaceutical formulations.

PubMed

Mohammadi, Ali; Mohammadi, Somayeh; Bayandori Moghaddam, Abdolmajid; Masoumi, Vahideh; Walker, Roderick B

2014-10-01

In this study, a simple method was developed and validated to detect trace levels of benzaldehyde in injectable pharmaceutical formulations by solid-phase microextraction coupled with gas chromatography-flame ionization detector. Polyaniline was electrodeposited on a platinum wire in trifluoroacetic acid solvent by cyclic voltammetry technique. This fiber shows high thermal and mechanical stability and high performance in extraction of benzaldehyde. Extraction and desorption time and temperature, salt effect and gas chromatography parameters were optimized as key parameters. At the optimum conditions, the fiber shows good linearity between peak area ratio of benzaldehyde/3-chlorobenzaldehyde and benzaldehyde concentration in the range of 50-800 ng/mL with percent relative standard deviation values ranging from 0.75 to 8.64% (n = 3). The limits of quantitation and detection were 50 and 16 ng/mL, respectively. The method has the requisite selectivity, sensitivity, accuracy and precision to assay benzaldehyde in injectable pharmaceutical dosage forms. © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A simple solid phase, peptide-based fluorescent assay for the efficient and universal screening of HRV 3C protease inhibitors.

PubMed

Schünemann, Katrin; Connelly, Stephen; Kowalczyk, Renata; Sperry, Jonathan; Wilson, Ian A; Fraser, John D; Brimble, Margaret A

2012-08-01

With over a 100 different serotypes, the human rhinovirus (HRV) is the major aetiological agent for the common cold, for which only symptomatic treatment is available. HRV maturation and replication is entirely dependent on the activity of a virally encoded 3C protease that represents an attractive target for the development of therapeutics to treat the common cold. Although a variety of small molecules and peptidomimetics have been found to inhibit HRV 3C protease, no universally compatible assay exists to reliably quantify the activity of the enzyme in vitro. Herein we report the development of a universal and robust solid phase peptide assay that utilizes the full HRV-14 3C protease recognition sequence and the release of 5(6)-carboxyfluorescein to sensitively quantify protease activity. This novel assay overcomes several limitations of existing assays allowing for the simple and efficient analysis of HRV-14 3C protease activity facilitating both high-throughput screening and the accurate kinetic study of HRV-14 3C protease inhibitors. Copyright © 2012 Elsevier Ltd. All rights reserved.

Application of solid-phase microextraction to the quantitative analysis of 1,8-cineole in blood and expired air in a Eucalyptus herbivore, the brushtail possum (Trichosurus vulpecula).

PubMed

Boyle, Rebecca R; McLean, Stuart; Brandon, Sue; Pass, Georgia J; Davies, Noel W

2002-11-25

We have developed two solid-phase microextraction (SPME) methods, coupled with gas chromatography, for quantitatively analysing the major Eucalyptus leaf terpene, 1,8-cineole, in both expired air and blood from the common brushtail possum (Trichosurus vulpecula). In-line SPME sampling (5 min at 20 degrees C room temperature) of excurrent air from an expiratory chamber containing a possum dosed orally with 1,8-cineole (50 mg/kg) allowed real-time semi-quantitative measurements reflecting 1,8-cineole blood concentrations. Headspace SPME using 50 microl whole blood collected from possums dosed orally with 1,8-cineole (30 mg/kg) resulted in excellent sensitivity (quantitation limit 1 ng/ml) and reproducibility. Blood concentrations ranged between 1 and 1380 ng/ml. Calibration curves were prepared for two concentration ranges (0.05-10 and 10-400 ng/50 microl) for the analysis of blood concentrations. Both calibration curves were linear (r(2)=0.999 and 0.994, respectively) and the equations for the two concentration ranges were consistent. Copyright 2002 Elsevier Science B.V.

Determination of polychlorinated biphenyls in ocean water and bovine milk using crosslinked polymeric ionic liquid sorbent coatings by solid-phase microextraction.

PubMed

Joshi, Manishkumar D; Ho, Tien D; Cole, William T S; Anderson, Jared L

2014-01-01

Crosslinked polymeric ionic liquid (PIL)-based sorbent coatings were employed in the extraction of 21 polychlorinated biphenyls (PCBs) from ocean water and bovine milk using solid-phase microextraction (SPME). The extraction temperature, time, and concentration of sodium chloride added to the matrix were optimized in order to determine the best extraction conditions for the extraction of PCBs. The analytical performance of the crosslinked PIL-based SPME fibers was compared with a commercial 7 µm polydimethylsiloxane (PDMS) fiber using gas chromatography (GC) employing an electron capture detector (ECD) and mass spectrometric detection (MS). Higher sensitivities for PCBs were achieved using PIL-based fibers when compared to PDMS fiber due to the incorporation of benzyl moieties into the PIL structures. The limits of detection (LOD) for all PCBs were determined to be in the low ng L(-1) range using the three studied coatings. Recovery studies were performed for PCBs in ocean water and bovine milk to validate the applicability of the current SPME method. © 2013 Published by Elsevier B.V.

On-chip sample pretreatment using a porous polymer monolithic column for solid-phase microextraction and chemiluminescence determination of catechins in green tea.

PubMed

Lin, Ling; Chen, Hui; Wei, Huibin; Wang, Feng; Lin, Jin-Ming

2011-10-21

A porous polymer monolithic column for solid-phase microextraction and chemiluminescence detection was integrated into a simple microfluidic chip for the extraction and determination of catechins in green tea. The porous polymer was prepared by poly(glycidyl methacrylate-co-ethylene dimethacrylate) and modified with ethylenediamine. Catechins can be concentrated in the porous polymer monolithic column and react with potassium permanganate to give chemiluminescence. The microfluidic chip is reusable with high sensitivity and very low reagent consumption. The on-line preconcentration and detection can be realized without an elution step. The enrichment factor was calculated to be about 20 for catechins. The relative chemiluminescence intensity increased linearly with concentration of catechin from 5.0 × 10(-9) to 1.0 × 10(-6) M and the limit of detection was 1.0 × 10(-9) M. The proposed method was applied to determine catechin in green tea. The recoveries are from 90% to 110% which benefits the actual application for green tea samples.

Miniaturized solid-phase extraction of macrolide antibiotics in honey and bovine milk using mesoporous MCM-41 silica as sorbent.

PubMed

Du, Li-Jing; Yi, Ling; Ye, Li-Hong; Chen, Yu-Bo; Cao, Jun; Peng, Li-Qing; Shi, Yu-Ting; Wang, Qiu-Yan; Hu, Yu-Han

2018-02-16

A simple and effective method of miniaturized solid-phase extraction (mini-SPE) was developed for the simultaneous purification and enrichment of macrolide antibiotics (MACs) (i.e. azithromycin, clarithromycin, erythromycin, lincomycin and roxithromycin) from honey and skim milk. Mesoporous MCM-41 silica was synthesized and used as sorbent in mini-SPE. Several key parameters affecting the performance of mini-SPE procedure were thoroughly investigated, including sorbent materials, amount of sorbent and elution solvents. Under the optimized condition, satisfactory linearity (r 2  > 0.99), acceptable precision (RSDs, 0.3-7.1%), high sensitivity (limit of detection in the range of 0.01-0.76 μg/kg), and good recoveries (83.21-105.34%) were obtained. With distinct advantages of simplicity, reliability and minimal sample requirement, the proposed mini-SPE procedure coupled with ultrahigh performance liquid chromatography and quadrupole time-of-flight tandem mass spectrometry could become an alternative tool to analyze the residues of MACs in complex food matrixes. Copyright © 2018 Elsevier B.V. All rights reserved.

Detection and quantification of cocaine and benzoylecgonine in meconium using solid phase extraction and UPLC/MS/MS.

PubMed

Gunn, Josh; Kriger, Scott; Terrell, Andrea R

2010-01-01

The simultaneous determination and quantification of cocaine and its major metabolite, benzoylecgonine, in meconium using UPLC-MS/MS is described. Ultra-performance liquid chromatography (UPLC) is an emerging analytical technique which draws upon the principles of chromatography to run separations at higher flow rates for increased speed, while simultaneously achieving superior resolution and sensitivity. Extraction of cocaine and benzoylecgonine from the homogenized meconium matrix was achieved with a preliminary protein precipitation or protein 'crash' employing cold acetonitrile, followed by a mixed mode solid phase extraction (SPE). Following elution from the SPE cartridge, eluents were dried down under nitrogen, reconstituted in 200 microL of DI water:acetonitrile (ACN) (75:25), and injected onto the UPLC/MS/MS for analysis. The increased speed and separation efficiency afforded by UPLC, allowed for the separation and subsequent quantification of both analytes in less than 2 min. Analytes were quantified using multiple reaction monitoring (MRM) and six-point calibration curves constructed in negative blood. Limits of detection for both analytes were 3 ng/g and the lower limit of quantitation (LLOQ) was 30 ng/g.

Application of solid phase extraction on multiwalled carbon nanotubes of some heavy metal ions to analysis of skin whitening cosmetics using ICP-AES.

PubMed

Alqadami, Ayoub A; Abdalla, Mohammad Abulhassan; AlOthman, Zeid A; Omer, Kamal

2013-01-14

A novel and highly sensitive method for the determination of some heavy metals in skin whitening cosmetics creams using multiwalled carbon nanotubes MWCNTs as solid phase extraction sorbent for the preconcentration of these heavy metals prior to their determination by inductively coupled plasma atomic emission spectrometry is described. Different practical parameters have been thoroughly investigated and the optimum experimental conditions were employed. The developed method was then applied for the determination of arsenic, bismuth, cadmium, mercury, lead and titanium in samples of skin whitening cosmetics. The detection limits under these conditions for As, Bi, Cd, Pb, Hg and Ti were 2.4, 4.08, 0.3, 2.1, 1.8, and 1.8 ng·mL-1, respectively. The relative standard deviations (RSDs) were found to be less than 2.0%. For validation, a certified reference material of NIST SRM 1570a spinach leaves was analyzed and the determined values were in good agreement with the certified values. The recoveries for spiked samples were found to be in the range of 89.6-104.4%.

Application of solid-phase microextraction for in vivo laboratory and field sampling of pharmaceuticals in fish.

PubMed

Zhou, Simon Ningsun; Oakes, Ken D; Servos, Mark R; Pawliszyn, Janusz

2008-08-15

Previous field studies utilizing solid-phase microextraction (SPME) predominantly focused on volatile and semivolatile compounds in air or water. Earlier in vivo sampling studies utilizing SPME were limited to the liquid matrix (blood). The present study has expanded the SPME technique to semisolid tissues under laboratory and field conditions through the investigation of both theoretical and applied experimental approaches. Pre-equilibrium extraction and desorption were performed in vivo in two separate animals. Excellent linearity was found between the amounts extracted by SPME from the muscle of living fish and the waterborne concentrations of pharmaceuticals. A simple SPME method is also described to simultaneously determine free and total analyte concentrations in living tissue. The utility of in vivo SPME sampling was evaluated in wild fish collected from a number of different river locations under varying degrees of influence from municipal wastewater effluents. Diphenhydramine and diltiazem were detected in the muscle of fish downstream of a local wastewater treatment plant. Based on this study, SPME demonstrated several important advantages such as simplicity, sensitivity, and robustness under laboratory and in vivo field sampling conditions.

Determination of furfural and hydroxymethylfurfural from baby formula using headspace solid phase microextraction based on nanostructured polypyrrole fiber coupled with ion mobility spectrometry.

PubMed

Kamalabadi, Mahdie; Ghaemi, Elham; Mohammadi, Abdorreza; Alizadeh, Naader

2015-08-15

Furfural (Fu) and hydroxymethylfurfural (HMFu) are extracted using a dodecylbenzenesulfonate-doped polypyrrole coating as a fiber for headspace solid phase microextraction (HS-SPME) method in baby formula samples and detected using ion mobility spectrometry (IMS). Sample pH, salt effect, extraction time and temperature were investigated and optimized as effective parameters in HS-SPME. The calibration curves were linear in the range of 20-300 ng g(-1) (R(2)>0.99). Limits of detection for Fu and HMFu were 6 ng g(-1) and 5 ng g(-1), respectively. The RSD% of Fu and HMFu for five analyses was 4.4 and 4.9, respectively. The proposed method was successfully applied to determine of Fu and HMFu in the different baby formula samples with satisfactory result. The results were in agreement with those obtained using HPLC analysis. The HS-SPME-IMS is precise, selective and sensitive analytical method for determination of Fu and HMFu in baby formula samples, without any derivatization process. Copyright © 2015 Elsevier Ltd. All rights reserved.

Determination of phthalate esters from environmental water samples by micro-solid-phase extraction using TiO2 nanotube arrays before high-performance liquid chromatography.

PubMed

Zhou, Qingxiang; Fang, Zhi; Liao, Xiangkun

2015-07-01

We describe a highly sensitive micro-solid-phase extraction method for the pre-concentration of six phthalate esters utilizing a TiO2 nanotube array coupled to high-performance liquid chromatography with a variable-wavelength ultraviolet visible detector. The selected phthalate esters included dimethyl phthalate, diethyl phthalate, dibutyl phthalate, butyl benzyl phthalate, bis(2-ethylhexyl)phthalate and dioctyl phthalate. The factors that would affect the enrichment, such as desorption solvent, sample pH, salting-out effect, extraction time and desorption time, were optimized. Under the optimum conditions, the linear range of the proposed method was 0.3-200 μg/L. The limits of detection were 0.04-0.2 μg/L (S/N = 3). The proposed method was successfully applied to the determination of six phthalate esters in water samples and satisfied spiked recoveries were achieved. These results indicated that the proposed method was appropriate for the determination of trace phthalate esters in environmental water samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preconcentration and solid phase extraction method for the determination of Co, Cu, Ni, Zn and Cd in environmental and biological samples using activated carbon by FAAS.

PubMed

Kiran, K; Suresh Kumar, K; Suvardhan, K; Janardhanam, K; Chiranjeevi, P

2007-08-17

2-{[1-(2-Hydroxynaphthyl) methylidene] amino} benzoic acid (HNMABA) was synthesized for solid phase extraction (SPE) to the determination of Co, Cu, Ni, Zn and Cd in environmental and biological samples by flame atomic absorption spectrophotometry (FAAS). These metals were sorbed as HNMABA complexes on activated carbon (AC) at the pH range of 5.0+/-0.2 and eluted with 6 ml of 1M HNO3 in acetone. The effects of sample volume, eluent volume and recovery have been investigated to enhance the sensitivity and selectivity of proposed method. The effect of interferences on the sorption of metal ions was studied. The concentration of the metal ions detected after preconcentration was in agreement with the added amount. The detection limits for the metals studied were in the range of 0.75-3.82 microg ml(-1). The proposed system produced satisfactory results for the determination of Co, Cu, Ni, Zn and Cd metals in environmental and biological samples.

[Determination of 3-monochloropropane-1,2-diol in grease food by solid phase extraction-derivatization-gas chromatography-mass spectrometry].

PubMed

Xiang, Xiaoling; Wang, Liyuan; Shen, Xianghong; Li, Chunsong; Shen, Jianfu; Wu, Pinggu

2017-09-01

To establish the method of determination of 3-monochloropropane-1,2-diol( 3-MCPD) in grease food by gas chromatography-mass spectrometry( GC-MS). 3-MCPD in grease food represented by bean paste was extracted by ultrasound,purified by alkaline earth solid phase extraction column,derivatived using phenylboronic acid( PBA) and detected by GC-MS. The linearity of 3-MCPD ranged from 1-100 ng/mL,with correlation coefficient at 0. 9993.The limits of quantitation( LOQ) in soy sauce,bean paste,pepper oil were 0. 6,0. 5 and7. 0 μg/kg and limits of detection( LOD) were 1. 9,1. 6 and 18. 8 μg/kg,respectively.Average recovery rate and relative standard deviation was 78. 3%-106. 7% and 1. 9%-11. 6%( n = 6), when 3-MCPD was added in grease food at 2. 5-1000 μg/kg. The method has good purification effect and the detection sensitivity and accuracy,and can be used for the determination of 3-MCPD in grease food.

Enrichment and determination of octylphenol and nonylphenol in environmental water samples by solid-phase microextraction with carboxylated carbon nano-spheres coating prior to gas chromatography-mass spectrometry.

PubMed

Gong, Sheng-Xiang; Wang, Xia; Li, Lei; Wang, Ming-Lin; Zhao, Ru-Song

2015-11-01

In this paper, a novel and simple method for the sensitive determination of endocrine disrupter compounds octylphenol (OP) and nonylphenol (NP) in environmental water samples has been developed using solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry. Carboxylated carbon nano-spheres (CNSs-COOH) are used as a novel SPME coating via physical adhesion. The CNSs-COOH fiber possessed higher adsorption efficiency than 100 μm polydimethysiloxane (PDMS) fiber and was similar to 85 μm polyacrylate (PA) fiber for the two analytes. Important parameters, such as extraction time, pH, agitation speed, ionic strength, and desorption temperature and time, were investigated and optimized in detail. Under the optimal parameters, the developed method achieved low limits of detection of 0.13~0.14 ng·L(-1) and a wide linear range of 1~1000 ng·(-1) for OP and NP. The novel method was validated with several real environmental water samples, and satisfactory results were obtained.

Monolithic molecular imprinted polymer fiber for recognition and solid phase microextraction of ephedrine and pseudoephedrine in biological samples prior to capillary electrophoresis analysis.

PubMed

Deng, Dong-Li; Zhang, Ji-You; Chen, Chen; Hou, Xiao-Ling; Su, Ying-Ying; Wu, Lan

2012-01-06

A novel capillary electrophoresis (CE) method coupled with monolithic molecular imprinted polymer (MIP) fiber based solid phase microextraction (SPME) was developed for selective and sensitive determination of ephedrine (E) and pseudoephedrine (PE). With in situ polymerization in a silica capillary mold and E as template, the MIP fibers could be produced in batch reproducibly and each fiber was available for 50 extraction cycles without significant decrease in extraction ability. Using the MIP fiber under optimized extraction conditions, CE detection limits of E and PE were greatly lowered from 0.20 to 0.00096 μg/mL and 0.12 to 0.0011 μg/mL, respectively. Analysis of urine and serum samples by the MIP-SPME-CE method was also performed, with results indicating that E and PE could be selectively extracted. The recoveries and relative standard deviations (RSDs) for sample analysis were found in the range of 91-104% and 3.8-9.1%, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

Ionic liquids in solid-phase microextraction: a review.

PubMed

Ho, Tien D; Canestraro, Anthony J; Anderson, Jared L

2011-06-10

Solid-phase microextraction (SPME) has undergone a surge in popularity within the field of analytical chemistry in the past two decades since its introduction. Owing to its nature of extraction, SPME has become widely known as a quick and cost-effective sample preparation technique. Although SPME has demonstrated extraordinary versatility in sampling capabilities, the technique continues to experience a tremendous growth in innovation. Presently, increasing efforts have been directed towards the engineering of novel sorbent material in order to expand the applicability of SPME for a wider range of analytes and matrices. This review highlights the application of ionic liquids (ILs) and polymeric ionic liquids (PILs) as innovative sorbent materials for SPME. Characterized by their unique physico-chemical properties, these compounds can be structurally-designed to selectively extract target analytes based on unique molecular interactions. To examine the advantages of IL and PIL-based sorbent coatings in SPME, the field is reviewed by gathering available experimental data and exploring the sensitivity, linear calibration range, as well as detection limits for a variety of target analytes in the methods that have been developed. Copyright © 2011 Elsevier B.V. All rights reserved.

Determination of acidic herbicides in surface water by solid-phase extraction followed by capillary zone electrophoresis.

PubMed

Qin, Weidong; Wei, Hongping; Li, Sam Fong Yau

2002-08-01

A rapid solid-phase extraction-capillary zone electrophoresis (CZE) method for determining 2,4-dichlorophenoxyacetic acid, 4-(2,4-dichlorophenoxy) butyric acid, and 2,4,5-trichlorophenoxyacetic acid in real water samples is described. Factors affecting the recoveries and detection of the targets are investigated. With samples being acidified to pH 2 and salted by sodium sulfate to 2% (w/w), an average recovery of greater than 85% is obtained using ethyl acetate as the eluent on an octadecylsilane-bonded silica cartridge. A running buffer of 5 mM sodium tetraborate in a water-acetonitrile mixture (70:30, v/v) adjusted to pH 9 is employed in the CZE analysis, and the targets can be analyzed within 7 min with good reproducibility and acceptable sensitivity. The method is suitable for detecting herbicide residues of sub-parts-per-billion levels in surface water. A local pond water is analyzed, and the concentrations of 2,4-dichlorophenoxyacetic acid and 4-(2,4-dichlorophenoxy) butyric acid are detected to be 0.27 +/- 0.03 ppb and 0.61 +/- 0.08 ppb, respectively.

Preparation of the very acid-sensitive Fmoc-Lys(Mtt)-OH. Application in the synthesis of side-chain to side-chain cyclic peptides and oligolysine cores suitable for the solid-phase assembly of MAPs and TASPs.

PubMed

Aletras, A; Barlos, K; Gatos, D; Koutsogianni, S; Mamos, P

1995-05-01

N alpha-9-Fluorenylmethoxycarbonyl-N epsilon-4=methyltrityl-lysine, [Fmoc-Lys(Mtt)-OH], was prepared in two steps from lysine, in 42% overall yield. The N epsilon-Mtt function can be quantitatively removed upon treatment with 1% TFA in dichloromethane or with a 1:2:7 mixture of acetic acid/trifluoroethanol/dichloromethane for 30 min and 1 h at room temperature, respectively. Under these conditions, groups of the tert-butyl type and peptide ester bonds to TFA-labile resins, such as the 2-chlorodiphenylmethyl- and the Wang-resin, remained intact. The utility of the new derivative in peptide synthesis has been exemplified with the synthesis of a cyclic cholecystokinin analog. As an example of further application, five types of lysine cores suitable for the solid-phase synthesis of one, two or three epitopes containing antigenic peptides or template-assembled synthetic proteins have been synthesized on Merrifield, Wang and 2-chlorodiphenylmethyl resin.

Simultaneous determination of sulfonamides, tetracyclines and tiamulin in swine wastewater by solid-phase extraction and liquid chromatography-mass spectrometry.

PubMed

Ben, Weiwei; Qiang, Zhimin; Adams, Craig; Zhang, Heqing; Chen, Liping

2008-08-22

Little is known about the contamination level of antibiotics in swine wastewater in China. The highly complex matrix of swine wastewater, which generally has a chemical oxygen demand (COD) concentration as high as 15,000 mg/L, makes it difficult to detect antibiotics at trace levels. In this work, a highly selective and sensitive analytical method was developed for simultaneous determination of three classes of commonly used veterinary antibiotics including five sulfonamides, three tetracyclines and one macrolide in swine wastewater using solid-phase extraction (SPE) and liquid chromatography-mass spectrometry (LC-MS). The method detection limits (MDL) in the swine wastewater were determined to be between 5 and 91 ng/L, depending on specific antibiotics. Except sulfamethizole, all the other eight antibiotics were detected in the swine wastewaters collected from three concentrated swine feeding plants located in the Beijing (China) area, showing a concentration range of 0.62-32.67 microg/L. These results reveal the representative concentration levels of selected antibiotics in the swine wastewaters of Beijing area.

Astragalin from Cassia alata Induces DNA Adducts in Vitro and Repairable DNA Damage in the Yeast Saccharomyces cerevisiae

PubMed Central

Saito, Samuel; Silva, Givaldo; Santos, Regineide Xavier; Gosmann, Grace; Pungartnik, Cristina; Brendel, Martin

2012-01-01

Reverse phase-solid phase extraction from Cassia alata leaves (CaRP) was used to obtain a refined extract. Higher than wild-type sensitivity to CaRP was exhibited by 16 haploid Saccharomyces cerevisiae mutants with defects in DNA repair and membrane transport. CaRP had a strong DPPH free radical scavenging activity with an IC50 value of 2.27 μg mL−1 and showed no pro-oxidant activity in yeast. CaRP compounds were separated by HPLC and the three major components were shown to bind to DNA in vitro. The major HPLC peak was identified as kampferol-3-O-β-d-glucoside (astragalin), which showed high affinity to DNA as seen by HPLC-UV measurement after using centrifugal ultrafiltration of astragalin-DNA mixtures. Astragalin-DNA interaction was further studied by spectroscopic methods and its interaction with DNA was evaluated using solid-state FTIR. These and computational (in silico) docking studies revealed that astragalin-DNA binding occurs through interaction with G-C base pairs, possibly by intercalation stabilized by H-bond formation. PMID:22489129

Astragalin from Cassia alata induces DNA adducts in vitro and repairable DNA damage in the yeast Saccharomyces cerevisiae.

PubMed

Saito, Samuel; Silva, Givaldo; Santos, Regineide Xavier; Gosmann, Grace; Pungartnik, Cristina; Brendel, Martin

2012-01-01

Reverse phase-solid phase extraction from Cassia alata leaves (CaRP) was used to obtain a refined extract. Higher than wild-type sensitivity to CaRP was exhibited by 16 haploid Saccharomyces cerevisiae mutants with defects in DNA repair and membrane transport. CaRP had a strong DPPH free radical scavenging activity with an IC(50) value of 2.27 μg mL(-1) and showed no pro-oxidant activity in yeast. CaRP compounds were separated by HPLC and the three major components were shown to bind to DNA in vitro. The major HPLC peak was identified as kampferol-3-O-β-d-glucoside (astragalin), which showed high affinity to DNA as seen by HPLC-UV measurement after using centrifugal ultrafiltration of astragalin-DNA mixtures. Astragalin-DNA interaction was further studied by spectroscopic methods and its interaction with DNA was evaluated using solid-state FTIR. These and computational (in silico) docking studies revealed that astragalin-DNA binding occurs through interaction with G-C base pairs, possibly by intercalation stabilized by H-bond formation.

Engineered glass seals for solid-oxide fuel cells

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

Surdoval, Wayne; Lara-Curzio, Edgar; Stevenson, Jeffry

2017-02-07

A seal for a solid oxide fuel cell includes a glass matrix having glass percolation therethrough and having a glass transition temperature below 650.degree. C. A deformable second phase material is dispersed in the glass matrix. The second phase material can be a compliant material. The second phase material can be a crushable material. A solid oxide fuel cell, a precursor for forming a seal for a solid oxide fuel cell, and a method of making a seal for a solid oxide fuel cell are also disclosed.

Solid electrolyte-electrode system for an electrochemical cell

DOEpatents

Tuller, H.L.; Kramer, S.A.; Spears, M.A.

1995-04-04

An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is also provided. 17 figures.

Rapid determination of the volatile components in tobacco by ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction with gas chromatography-mass spectrometry.

PubMed

Yang, Yanqin; Chu, Guohai; Zhou, Guojun; Jiang, Jian; Yuan, Kailong; Pan, Yuanjiang; Song, Zhiyu; Li, Zuguang; Xia, Qian; Lu, Xinbo; Xiao, Weiqiang

2016-03-01

An ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction was first employed to determine the volatile components in tobacco samples. The method combined the advantages of ultrasound, microwave, and headspace solid-phase microextraction. The extraction, separation, and enrichment were performed in a single step, which could greatly simplify the operation and reduce the whole pretreatment time. In the developed method, several experimental parameters, such as fiber type, ultrasound power, and irradiation time, were optimized to improve sampling efficiency. Under the optimal conditions, there were 37, 36, 34, and 36 components identified in tobacco from Guizhou, Hunan, Yunnan, and Zimbabwe, respectively, including esters, heterocycles, alkanes, ketones, terpenoids, acids, phenols, and alcohols. The compound types were roughly the same while the contents were varied from different origins due to the disparity of their growing conditions, such as soil, water, and climate. In addition, the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction method was compared with the microwave-assisted extraction coupled to headspace solid-phase microextraction and headspace solid-phase microextraction methods. More types of volatile components were obtained by using the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction method, moreover, the contents were high. The results indicated that the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction technique was a simple, time-saving and highly efficient approach, which was especially suitable for analysis of the volatile components in tobacco. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optimization of a method for preparing solid complexes of essential clove oil with β-cyclodextrins.

PubMed

Hernández-Sánchez, Pilar; López-Miranda, Santiago; Guardiola, Lucía; Serrano-Martínez, Ana; Gabaldón, José Antonio; Nuñez-Delicado, Estrella

2017-01-01

Clove oil (CO) is an aromatic oily liquid used in the food, cosmetics and pharmaceutical industries for its functional properties. However, its disadvantages of pungent taste, volatility, light sensitivity and poor water solubility can be solved by applying microencapsulation or complexation techniques. Essential CO was successfully solubilized in aqueous solution by forming inclusion complexes with β-cyclodextrins (β-CDs). Moreover, phase solubility studies demonstrated that essential CO also forms insoluble complexes with β-CDs. Based on these results, essential CO-β-CD solid complexes were prepared by the novel approach of microwave irradiation (MWI), followed by three different drying methods: vacuum oven drying (VO), freeze-drying (FD) or spray-drying (SD). FD was the best option for drying the CO-β-CD solid complexes, followed by VO and SD. MWI can be used efficiently to prepare essential CO-β-CD complexes with good yield on an industrial scale. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Liquid-phase and solid-phase microwave irradiations for reduction of graphite oxide

NASA Astrophysics Data System (ADS)

Zhao, Na; Wen, Chen-Yu; Zhang, David Wei; Wu, Dong-Ping; Zhang, Zhi-Bin; Zhang, Shi-Li

2014-12-01

In this paper, two microwave irradiation methods: (i) liquid-phase microwave irradiation (MWI) reduction of graphite oxide suspension dissolved in de-ionized water and N, N-dimethylformamide, respectively, and (ii) solid-phase MWI reduction of graphite oxide powder have been successfully carried out to reduce graphite oxide. The reduced graphene oxide products are thoroughly characterized by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectral analysis, Raman spectroscopy, UV-Vis absorption spectral analysis, and four-point probe conductivity measurements. The results show that both methods can efficiently remove the oxygen-containing functional groups attached to the graphite layers, though the solid-phase MWI reduction method can obtain far more efficiently a higher quality-reduced graphene oxide with fewer defects. The I(D)/I(G) ratio of the solid-phase MWI sample is as low as 0.46, which is only half of that of the liquid-phase MWI samples. The electrical conductivity of the reduced graphene oxide by the solid method reaches 747.9 S/m, which is about 25 times higher than that made by the liquid-phase method.

Organic Matter Transformation in the Peat Column at Marcell Experimental Forest: Humification and Vertical Stratification

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

Tfaily, Malak; Cooper, Bill; Kostka,

2014-01-01

A large-scale ecosystem manipulation (Spruce and Peatland Responses under Climatic and Environmental Change, SPRUCE) is being constructed in the Marcell Experimental Forest, Minnesota, USA, to determine the effects of climatic forcing on ecosystem processes in northern peatlands. Prior to the initiation of the manipulation, we characterized the solid-phase peat to a depth of 2 meters using a variety of techniques, including peat C:N ratios, 13C and 15N isotopic composition, Fourier Transform Infrared (FT IR), and 13C Nuclear Magnetic Resonance spectroscopy (13C NMR). FT IR determined peat humification-levels increased rapidly between and 75 cm, indicating a highly reactive zone. We observedmore » a rapid drop in the abundance of O-alkyl-C, carboxyl-C, and other oxygenated functionalities within this zone and a concomitant increase in the abundance of alkyl- and nitrogen-containing compounds. Below 75-cm, minimal change was observed except that aromatic functionalities accumulated with depth. Incubation studies revealed the highest methane production rates and greatest CH4:CO2 ratios within this and 75 cm zone. Hydrology and surface vegetation played a role in belowground carbon cycling. Radiocarbon signatures of microbial respiration products in deeper porewaters resembled the signatures of dissolved organic carbon rather than solid phase peat, indicating that more recently photosynthesized organic matter fueled the bulk of subsurface microbial respiration. Oxygen-containing functionalities, especially O-alkyl-C, appear to serve as an excellent proxy for soil decomposition rate, and in addition should be a sensitive indicator of the response of the solid phase peat to the climatic manipulation.« less

Fast determination of octinoxate and oxybenzone uv filters in swimming pool waters by gas chromatography/mass spectrometry after solid-phase microextraction.

PubMed

Yılmazcan, Ö; Kanakaki, C; Izgi, B; Rosenberg, E

2015-07-01

A fast gas chromatography/mass spectrometry method was developed and validated for the analysis of the potential endocrine disrupters octinoxate and oxybenzone in swimming pool water samples based on the solvent-free solid-phase microextraction technique. The low-pressure gas chromatography/mass spectrometry method used for the fast identification of UV filter substances was compared to a conventional method in terms of sensitivity and speed. The fast method proposed resulted in 2 min runs, leading to an eightfold decrease in the total analysis time and a sevenfold improvement in detection limits. The main parameters affecting the solid-phase microextraction process were also studied in detail and the optimized conditions were as follows: fiber coating, polyacrylate; extraction mode, direct immersion; extraction temperature, 25°C; sample volume, 5 mL; extraction time 45 min; pH 6.5. Under the optimized conditions, a linear response was obtained in the concentration range of 0.5-25 μg/L with correlation coefficients in the range 0.990-0.999. The limits of detection were 0.17-0.29 μg/L, and the recoveries were 80-83%. Combined method uncertainty was assessed and found to be less than 7% for both analytes for concentrations equal to or higher than 5 μg/L. Pool water samples were analyzed to demonstrate the applicability of the proposed method. Neither octinoxate nor oxybenzone were detected in the swimming pool water samples at concentrations above the respective limits of detection. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Paper-based solid-phase nucleic acid hybridization assay using immobilized quantum dots as donors in fluorescence resonance energy transfer.

PubMed

Noor, M Omair; Shahmuradyan, Anna; Krull, Ulrich J

2013-02-05

A paper-based solid-phase assay is presented for transduction of nucleic acid hybridization using immobilized quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET). The surface of paper was modified with imidazole groups to immobilize QD-probe oligonucleotide conjugates that were assembled in solution. Green-emitting QDs (gQDs) were FRET-paired with Cy3 acceptor. Hybridization of Cy3-labeled oligonucleotide targets provided the proximity required for FRET-sensitized emission from Cy3, which served as an analytical signal. The assay exhibited rapid transduction of nucleic acid hybridization within minutes. Without any amplification steps, the limit of detection of the assay was found to be 300 fmol with the upper limit of the dynamic range at 5 pmol. The implementation of glutathione-coated QDs for the development of nucleic acid hybridization assay integrated on a paper-based platform exhibited excellent resistance to nonspecific adsorption of oligonucleotides and showed no reduction in the performance of the assay in the presence of large quantities of noncomplementary DNA. The selectivity of nucleic acid hybridization was demonstrated by single-nucleotide polymorphism (SNP) detection at a contrast ratio of 19 to 1. The reuse of paper over multiple cycles of hybridization and dehybridization was possible, with less than 20% reduction in the performance of the assay in five cycles. This work provides an important framework for the development of paper-based solid-phase QD-FRET nucleic acid hybridization assays that make use of a ratiometric approach for detection and analysis.

Double-disk solid-phase extraction--Simultaneous cleanup and trace enrichment of herbicides and metabolites from environmental samples

USGS Publications Warehouse

Ferrar, Imma; Barceló, Damià; Thurman, E.M.

1999-01-01

Phenylurea and triazine herbicides, including some metabolites, were isolated from water and soil extracts by solid-phase extraction using a layered system of two extraction disks, a method called double-disk solid-phase extraction. The first disk consisted of strong anion exchange (SAX) of 10-μm styrene divinylbenzene (SDB) particles embedded in Teflon, and the second disk was a C18 disk of 10-μm particles also embedded in Teflon. A volume of 500 mL of water or aqueous soil extract is passed through the layered system with the SAX disk first. The purpose of the SAX disk is to remove the humic and fulvic acids from the water or aqueous soil extract by ion exchange through their carboxyl groups. Even during methanol elution of herbicides, the humic substances remain bound to the SAX disk with >85% retention. Elution with methanol results in more than 90% recovery of the herbicides from the layered extraction disks. Removal of the humic and fulvic acids results in greater sensitivity for diode array detection quantitation (0.05 μg/L for herbicides) by substantially reducing the absorbance of the humic peak on the LC chromatogram. The herbicides adsorb to the SAX disk either through hydrogen bonding to the anion-exchange sites or by hydrophobic interaction with the SDB surface of the anion-exchange disk. The method was tested for the analysis of natural water samples from the Mississippi Embayment, a cotton-growing area of the southeastern United States.

Headspace-Solid Phase Microextraction Approach for Dimethylsulfoniopropionate Quantification in Solanum lycopersicum Plants Subjected to Water Stress

PubMed Central

Catola, Stefano; Kaidala Ganesha, Srikanta Dani; Calamai, Luca; Loreto, Francesco; Ranieri, Annamaria; Centritto, Mauro

2016-01-01

Dimethylsulfoniopropionate (DMSP) and dimethyl sulphide (DMS) are compounds found mainly in marine phytoplankton and in some halophytic plants. DMS is a globally important biogenic volatile in regulating of global sulfur cycle and planetary albedo, whereas DMSP is involved in the maintenance of plant-environment homeostasis. Plants emit minute amounts of DMS compared to marine phytoplankton and there is a need for hypersensitive analytic techniques to enable its quantification in plants. Solid Phase Micro Extraction from Head Space (HS-SPME) is a simple, rapid, solvent-free and cost-effective extraction mode, which can be easily hyphenated with GC-MS for the analysis of volatile organic compounds. Using tomato (Solanum lycopersicum) plants subjected to water stress as a model system, we standardized a sensitive and accurate protocol for detecting and quantifying DMSP pool sizes, and potential DMS emissions, in cryoextracted leaves. The method relies on the determination of DMS free and from DMSP pools before and after the alkaline hydrolysis via Headspace-Solid Phase Micro Extraction-Gas Chromatography-Mass Spectrometry (HS-SPME-GC-MS). We found a significant (2.5 time) increase of DMSP content in water-stressed leaves reflecting clear stress to the photosynthetic apparatus. We hypothesize that increased DMSP, and in turn DMS, in water-stressed leaves are produced by carbon sources other than direct photosynthesis, and function to protect plants either osmotically or as antioxidants. Finally, our results suggest that SPME is a powerful and suitable technique for the detection and quantification of biogenic gasses in trace amounts. PMID:27602039

Multiple monolithic fiber solid-phase microextraction based on a polymeric ionic liquid with high-performance liquid chromatography for the determination of steroid sex hormones in water and urine.

PubMed

Liao, Keren; Mei, Meng; Li, Haonan; Huang, Xiaojia; Wu, Cuiqin

2016-02-01

The development of a simple and sensitive analytical approach that combines multiple monolithic fiber solid-phase microextraction with liquid desorption followed by high-performance liquid chromatography with diode array detection is proposed for the determination of trace levels of seven steroid sex hormones (estriol, 17β-estradiol, testosterone, ethinylestradiol, estrone, progesterone and mestranol) in water and urine matrices. To extract the target analytes effectively, multiple monolithic fiber solid-phase microextraction based on a polymeric ionic liquid was used to concentrate hormones. Several key extraction parameters including desorption solvent, extraction and desorption time, pH value and ionic strength in sample matrix were investigated in detail. Under the optimal experimental conditions, the limits of detection were found to be in the range of 0.027-0.12 μg/L. The linear range was 0.10-200 μg/L for 17β-estradiol, 0.25-200 μg/L estriol, ethinylestradiol and estrone, and 0.50-200 μg/L for the other hormones. Satisfactory linearities were achieved for analytes with the correlation coefficients above 0.99. Acceptable method reproducibility was achieved by evaluating the repeatability and intermediate precision with relative standard deviations of both less than 8%. The enrichment factors ranged from 54- to 74-fold. Finally, the proposed method was successfully applied to the analysis of steroid sex hormones in environmental water samples and human urines with spiking recoveries ranged from 75.6 to 116%. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Direct magnetic field estimation based on echo planar raw data.

PubMed

Testud, Frederik; Splitthoff, Daniel Nicolas; Speck, Oliver; Hennig, Jürgen; Zaitsev, Maxim

2010-07-01

Gradient recalled echo echo planar imaging is widely used in functional magnetic resonance imaging. The fast data acquisition is, however, very sensitive to field inhomogeneities which manifest themselves as artifacts in the images. Typically used correction methods have the common deficit that the data for the correction are acquired only once at the beginning of the experiment, assuming the field inhomogeneity distribution B(0) does not change over the course of the experiment. In this paper, methods to extract the magnetic field distribution from the acquired k-space data or from the reconstructed phase image of a gradient echo planar sequence are compared and extended. A common derivation for the presented approaches provides a solid theoretical basis, enables a fair comparison and demonstrates the equivalence of the k-space and the image phase based approaches. The image phase analysis is extended here to calculate the local gradient in the readout direction and improvements are introduced to the echo shift analysis, referred to here as "k-space filtering analysis." The described methods are compared to experimentally acquired B(0) maps in phantoms and in vivo. The k-space filtering analysis presented in this work demonstrated to be the most sensitive method to detect field inhomogeneities.

Packed in-tube solid phase microextraction with graphene oxide supported on aminopropyl silica: Determination of target triazines in water samples.

PubMed

De Toffoli, Ana L; Fumes, Bruno H; Lanças, Fernando M

2018-02-22

On-line in-tube solid phase microextraction (in-tube SPME) coupled to high performance liquid chromatography and tandem mass spectrometry (HPLC-MS/MS) was successfully applied to the determination of selected triazines in water samples. The method based on the employment of a packed column containing graphene oxide (GO) supported on aminopropyl silica (Si) showed that the extraction phase has a high potential for triazines extraction aiming to its physical-chemical properties including ultrahigh specific surface area, good mechanical and thermal stability and high fracture strength. Injection volume and loading time were both investigated and optimized. The method validation using Si-GO to extract and concentrate the analytes showed satisfactory results, good sensitivity, good linearity (0.2-4.0 µg L -1 ) and low detection limits (1.1-2.9 ng L -1 ). The high extraction efficiency was determined with enrichment factors ranging from 1.2-2.9 for the lowest level, 1.3-4.9 intermediate level and 1.2-3.0 highest level (n = 3). Although the analytes were not detected in the real samples evaluated, the method has demonstrated to be efficient through its application in the analysis of spiked triazines in ground and mineral water samples.

Estimating production and consumption of solid reactive Fe phases in marine sediments from concentration profiles

EPA Science Inventory

1D diffusion models may be used to estimate rates of production and consumption of dissolved metabolites in marine sediments, but are applied less often to the solid phase. Here we used a numerical inverse method to estimate solid phase Fe(III) and Fe(II) consumption and product...

Volatile fingerprints of seeds of four species indicate the involvement of alcoholic fermentation, lipid peroxidation, and Maillard reactions in seed deterioration during ageing and desiccation stress

PubMed Central

Colville, Louise

2012-01-01

The volatile compounds released by orthodox (desiccation-tolerant) seeds during ageing can be analysed using gas chromatography–mass spectrometry (GC-MS). Comparison of three legume species (Pisum sativum, Lathyrus pratensis, and Cytisus scoparius) during artificial ageing at 60% relative humidity and 50 °C revealed variation in the seed volatile fingerprint between species, although in all species the overall volatile concentration increased with storage period, and changes could be detected prior to the onset of viability loss. The volatile compounds are proposed to derive from three main sources: alcoholic fermentation, lipid peroxidation, and Maillard reactions. Lipid peroxidation was confirmed in P. sativum seeds through analysis of malondialdehyde and 4-hydroxynonenal. Volatile production by ageing orthodox seeds was compared with that of recalcitrant (desiccation-sensitive) seeds of Quercus robur during desiccation. Many of the volatiles were common to both ageing orthodox seeds and desiccating recalcitrant seeds, with alcoholic fermentation forming the major source of volatiles. Finally, comparison was made between two methods of analysis; the first used a Tenax adsorbent to trap volatiles, whilst the second used solid phase microextraction to extract volatiles from the headspace of vials containing powdered seeds. Solid phase microextraction was found to be more sensitive, detecting a far greater number of compounds. Seed volatile analysis provides a non-invasive means of characterizing the processes involved in seed deterioration, and potentially identifying volatile marker compounds for the diagnosis of seed viability loss. PMID:23175670

Confirmatory and quantitative analysis of fatty acid esters of hydroxy fatty acids in serum by solid phase extraction coupled to liquid chromatography tandem mass spectrometry.

PubMed

López-Bascón, María Asunción; Calderón-Santiago, Mónica; Priego-Capote, Feliciano

2016-11-02

A novel class of endogenous mammalian lipids endowed with antidiabetic and anti-inflammatory properties has been recently discovered. These are fatty acid esters of hydroxy fatty acids (FAHFAs) formed by condensation between a hydroxy fatty acid and a fatty acid. FAHFAs are present in human serum and tissues at low nanomolar concentrations. Therefore, high sensitivity and selectivity profiling analysis of these compounds in clinical samples is demanded. An automated qualitative and quantitative method based on on-line coupling between solid phase extraction and liquid chromatography-tandem mass spectrometry has been here developed for determination of FAHFAs in serum with the required sensitivity and selectivity. Matrix effects were evaluated by preparation of calibration models in serum and methanol. Recovery factors ranged between 73.8 and 100% in serum. The within-day variability ranged from 7.1 to 13.8%, and the between-days variability varied from 9.3 to 21.6%, which are quite acceptable values taking into account the low concentration levels at which the target analytes are found. The method has been applied to a cohort of human serum samples to estimate the concentrations profiles as a function of the glycaemic state and obesity. Statistical analysis revealed three FAHFAs with levels significantly different depending on the glycaemic state or the body mass index. This automated method could be implemented in high-throughput analysis with minimum user assistance. Copyright © 2016 Elsevier B.V. All rights reserved.

Total and Viable Legionella pneumophila Cells in Hot and Natural Waters as Measured by Immunofluorescence-Based Assays and Solid-Phase Cytometry ▿†

PubMed Central

Parthuisot, N.; Binet, M.; Touron-Bodilis, A.; Pougnard, C.; Lebaron, P.; Baudart, J.

2011-01-01

A new method was developed for the rapid and sensitive detection of viable Legionella pneumophila. The method combines specific immunofluorescence (IF) staining using monoclonal antibodies with a bacterial viability marker (ChemChrome V6 cellular esterase activity marker) by means of solid-phase cytometry (SPC). IF methods were applied to the detection and enumeration of both the total and viable L. pneumophila cells in water samples. The sensitivity of the IF methods coupled to SPC was 34 cells liter−1, and the reproducibility was good, with the coefficient of variation generally falling below 30%. IF methods were applied to the enumeration of total and viable L. pneumophila cells in 46 domestic hot water samples as well as in cooling tower water and natural water samples, such as thermal spring water and freshwater samples. Comparison with standard plate counts showed that (i) the total direct counts were always higher than the plate counts and (ii) the viable counts were higher than or close to the plate counts. With domestic hot waters, when the IF assay was combined with the viability test, SPC detected up to 3.4 × 103 viable but nonculturable L. pneumophila cells per liter. These direct IF methods could be a powerful tool for high-frequency monitoring of domestic hot waters or for investigating the occurrence of viable L. pneumophila in both man-made water systems and environmental water samples. PMID:21742913

Rapid and sensitive detection of the phenoxy acid herbicides in environmental water samples by magnetic solid-phase extraction combined with liquid chromatography-tandem mass spectrometry.

PubMed

Peng, Mao-Min; Han, Ya-Quan; Xia, Hong; Hu, Xi-Zhou; Zhou, You-Xiang; Peng, Li-Jun; Peng, Xi-Tian

2018-05-01

Phenoxy acid herbicides are widely used herbicides that play an important role in improving the yield and quality of crops. However, some research has shown that this kind of herbicide is poisonous to human and animals. In this study, a rapid and sensitive method was developed for the detection of seven phenoxy acid herbicides in water samples based on magnetic solid-phase extraction followed by liquid chromatography and tandem mass spectrometry. Magnetic amino-functionalized multiwalled carbon nanotubes were prepared by mixing bare magnetic Fe 3 O 4 nanoparticles with commercial amino-functionalized multiwalled carbon nanotubes in water. Then the amino-functionalized multiwalled carbon nanotubes were used to enrich phenoxy acid herbicides from water samples based on hydrophobic and ionic interactions. The effects of experimental variables on the extraction efficiency have been studied in detail. Under the optimized conditions, the method validation was performed. Good linearities for seven phenoxy acid herbicides were obtained with squared regression coefficients ranging from 0.9971 to 0.9989. The limits of detection ranged from 0.01 to 0.02 μg/L. The method recoveries of seven phenoxy acid herbicides spiked at three concentration levels in a blank sample were from 92.3 to 103.2%, with inter- and intraday relative standard deviations less than 12.6%. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Towards the determination of sulfonamides in meat samples: A magnetic and mesoporous metal-organic framework as an efficient sorbent for magnetic solid phase extraction combined with high-performance liquid chromatography.

PubMed

Xia, Lian; Liu, Lijie; Lv, Xiaoxia; Qu, Fei; Li, Guoliang; You, Jinmao

2017-06-02

A magnetic, mesoporous core/shell structured Fe 3 O 4 @JUC-48 nanocomposite was synthesized and employed as a magnetic solid phase extraction (MSPE) sorbent for the determination of trace sulfonamides (SAs) in meat samples. The synthesized nanocomposite was characterized by X-ray diffraction, Fourier transform infrared spectra, transmission electron microscopy, scanning electron microscopy, Brunner-Emmet-Teller, and vibrating sample magnetometry; the Fe 3 O 4 @JUC-48 nanocomposite exhibited a distinctive morphology, large surface area, high magnetism, open adsorption sites, and high chemical stability. By combining the optimized MSPE conditions with high performance liquid chromatography diode array detection, an accurate and sensitive method for the determination of 5 SAs, including sulfadiazine (SDZ), sulfathiazole (STZ), sulfamerazine (SMR), sulfamethazine (SMZ), and sulfamethoxypyridazine (SMP), was developed. The method exhibited good linearity in the range of 3.97-1000ng/g with R ranging from 0.9991 to 0.9994, high sensitivity with LODs ranging from 1.73 to 5.23ng/g, adequate recoveries between 76.1 and 102.6% with low relative standard deviations ranging from 2.1 to 6.4%, and high precision with RSD<4.5%. The Fe 3 O 4 @JUC-48 magnetic nanocomposite is a promising sorbent for the rapid and efficient extraction of SAs from complex biological samples such as chicken, pork, and shrimp. Copyright © 2017 Elsevier B.V. All rights reserved.

Stress-induced phase sensitivity of small diameter polarization maintaining solid-core photonic crystal fibre

NASA Astrophysics Data System (ADS)

Zhang, Zhihao; Zhang, Chunxi; Xu, Xiaobin

2017-09-01

Small diameter (cladding and coating diameter of 100 and 135 μm) polarization maintaining photonic crystal fibres (SDPM-PCFs) possess many unique properties and are extremely suitable for applications in fibre optic gyroscopes. In this study, we have investigated and measured the stress characteristics of an SDPM-PCF using the finite-element method and a Mach-Zehnder interferometer, respectively. Our results reveal a radial and axial sensitivity of 0.315 ppm/N/m and 25.2 ppm per 1 × 105 N/m2, respectively, for the SDPM-PCF. These values are 40% smaller than the corresponding parameters of conventional small diameter (cladding and coating diameter of 80 and 135 μm) panda fibres.

Modulated structure and molecular dissociation of solid chlorine at high pressures

NASA Astrophysics Data System (ADS)

Li, Peifang; Gao, Guoying; Ma, Yanming

2012-08-01

Among diatomic molecular halogen solids, high pressure structures of solid chlorine (Cl2) remain elusive and least studied. We here report first-principles structural search on solid Cl2 at high pressures through our developed particle-swarm optimization algorithm. We successfully reproduced the known molecular Cmca phase (phase I) at low pressure and found that it remains stable up to a high pressure 142 GPa. At 150 GPa, our structural searches identified several energetically competitive, structurally similar, and modulated structures. Analysis of the structural results and their similarity with those in solid Br2 and I2, it was suggested that solid Cl2 adopts an incommensurate modulated structure with a modulation wave close to 2/7 in a narrow pressure range 142-157 GPa. Eventually, our simulations at >157 GPa were able to predict the molecular dissociation of solid Cl2 into monatomic phases having body centered orthorhombic (bco) and face-centered cubic (fcc) structures, respectively. One unique monatomic structural feature of solid Cl2 is the absence of intermediate body centered tetragonal (bct) structure during the bco → fcc transition, which however has been observed or theoretically predicted in solid Br2 and I2. Electron-phonon coupling calculations revealed that solid Cl2 becomes superconductors within bco and fcc phases possessing a highest superconducting temperature of 13.03 K at 380 GPa. We further probed the molecular Cmca → incommensurate phase transition mechanism and found that the softening of the Ag vibrational (rotational) Raman mode in the Cmca phase might be the driving force to initiate the transition.

Solid-solution CrCoCuFeNi high-entropy alloy thin films synthesized by sputter deposition

DOE PAGES

An, Zhinan; Jia, Haoling; Wu, Yueying; ...

2015-05-04

The concept of high configurational entropy requires that the high-entropy alloys (HEAs) yield single-phase solid solutions. However, phase separations are quite common in bulk HEAs. A five-element alloy, CrCoCuFeNi, was deposited via radio frequency magnetron sputtering and confirmed to be a single-phase solid solution through the high-energy synchrotron X-ray diffraction, energy-dispersive spectroscopy, wavelength-dispersive spectroscopy, and transmission electron microscopy. The formation of the solid-solution phase is presumed to be due to the high cooling rate of the sputter-deposition process.

Method for making an electrochemical cell

DOEpatents

Tuller, Harry L.; Kramer, Steve A.; Spears, Marlene A.; Pal, Uday B.

1996-01-01

An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is provided.

Influences of pressure on methyl group, elasticity, sound velocity and sensitivity of solid nitromethane

NASA Astrophysics Data System (ADS)

Zhong, Mi; Liu, Qi-Jun; Qin, Han; Jiao, Zhen; Zhao, Feng; Shang, Hai-Lin; Liu, Fu-Sheng; Liu, Zheng-Tang

2017-06-01

First-principles calculations were employed to investigate the influences of pressure on methyl group, elasticity, sound velocity and sensitivity of solid nitromethane. The obtained structural parameters based on the GGA-PB E +G calculations are in good agreement with theoretical and experimental data. The rotation of methyl group appears under pressure, which influences the mechanical, thermal properties and sensitivity of solid NM. The anisotropy of elasticity, sound velocity and Debye temperature under pressure have been shown, which are related to the thermal properties of solid NM. The enhanced sensitivity with the increasing pressure has been discussed and the change of the most likely transition path is associated with methyl group.

Pressure induced solid-solid reconstructive phase transition in LiGa O2 dominated by elastic strain

NASA Astrophysics Data System (ADS)

Hu, Qiwei; Yan, Xiaozhi; Lei, Li; Wang, Qiming; Feng, Leihao; Qi, Lei; Zhang, Leilei; Peng, Fang; Ohfuji, Hiroaki; He, Duanwei

2018-01-01

Pressure induced solid-solid reconstructive phase transitions for graphite-diamond, and wurtzite-rocksalt in GaN and AlN occur at significantly higher pressure than expected from equilibrium coexistence and their transition paths are always inconsistent with each other. These indicate that the underlying nucleation and growth mechanism in the solid-solid reconstructive phase transitions are poorly understood. Here, we propose an elastic-strain dominated mechanism in a reconstructive phase transition, β -LiGa O2 to γ -LiGa O2 , based on in situ high-pressure angle dispersive x-ray diffraction and single-crystal Raman scattering. This mechanism suggests that the pressure induced solid-solid reconstructive phase transition is neither purely diffusionless nor purely diffusive, as conventionally assumed, but a combination. The large elastic strains are accumulated, with the coherent nucleation, in the early stage of the transition. The elastic strains along the 〈100 〉 and 〈001 〉 directions are too large to be relaxed by the shear stress, so an intermediate structure emerges reducing the elastic strains and making the transition energetically favorable. At higher pressures, when the elastic strains become small enough to be relaxed, the phase transition to γ -LiGa O2 begins and the coherent nucleation is substituted with a semicoherent one with Li and Ga atoms disordered.

Comparison of the solid-phase extraction efficiency of a bounded and an included cyclodextrin-silica microporous composite for polycyclic aromatic hydrocarbons determination in water samples.

PubMed

Mauri-Aucejo, Adela; Amorós, Pedro; Moragues, Alaina; Guillem, Carmen; Belenguer-Sapiña, Carolina

2016-08-15

Solid-phase extraction is one of the most important techniques for sample purification and concentration. A wide variety of solid phases have been used for sample preparation over time. In this work, the efficiency of a new kind of solid-phase extraction adsorbent, which is a microporous material made from modified cyclodextrin bounded to a silica network, is evaluated through an analytical method which combines solid-phase extraction with high-performance liquid chromatography to determine polycyclic aromatic hydrocarbons in water samples. Several parameters that affected the analytes recovery, such as the amount of solid phase, the nature and volume of the eluent or the sample volume and concentration influence have been evaluated. The experimental results indicate that the material possesses adsorption ability to the tested polycyclic aromatic hydrocarbons. Under the optimum conditions, the quantification limits of the method were in the range of 0.09-2.4μgL(-1) and fine linear correlations between peak height and concentration were found around 1.3-70μgL(-1). The method has good repeatability and reproducibility, with coefficients of variation under 8%. Due to the concentration results, this material may represent an alternative for trace analysis of polycyclic aromatic hydrocarbons in water trough solid-phase extraction. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of tylosin residues in pig tissues using high-performance liquid chromatography.

PubMed

De Liguoro, M; Anfossi, P; Angeletti, R; Montesissa, C

1998-06-01

In accordance with the maximum residue limit of 100 micrograms kg-1 established by EU legislation, a simple and sensitive high-performance liquid chromatographic (HPLC) method was developed for the measurement of tylosin residues in pig tissues (fat, kidney, liver and muscle). Tylosin, a macrolide antibiotic, is extracted with water-methanol and cleaned-up by solid-phase extraction (SPE) on cation-exchange cartridges using methanol elution. Tylosin was determined by reversed-phase HPLC with UV detection at 280 nm and the mean recovery from pig tissues fortified in the range 50-200 micrograms kg-1 was 70-85%, with intra- and inter-day RSDs in the ranges 3.4-9.1 and 3.9-10.1% respectively.

New solid surface fluorescence methodology for lead traces determination using rhodamine B as fluorophore and coacervation scheme: Application to lead quantification in e-cigarette refill liquids.

PubMed

Talio, María C; Zambrano, Karen; Kaplan, Marcos; Acosta, Mariano; Gil, Raúl A; Luconi, Marta O; Fernández, Liliana P

2015-10-01

A new environmental friendly methodology based on fluorescent signal enhancement of rhodamine B dye is proposed for Pb(II) traces quantification using a preconcentration step based on the coacervation phenomenon. A cationic surfactant (cetyltrimethylammonium bromide, CTAB) and potassium iodine were chosen for this aim. The coacervate phase was collected on a filter paper disk and the solid surface fluorescence signal was determined in a spectrofluorometer. Experimental variables that influence on preconcentration step and fluorimetric sensitivity have been optimized using uni-variation assays. The calibration graph using zero th order regression was linear from 7.4×10(-4) to 3.4 μg L(-1) with a correlation coefficient of 0.999. Under the optimal conditions, a limit of detection of 2.2×10(-4) μg L(-1) and a limit of quantification of 7.4×10(-4) μg L(-1) were obtained. The method showed good sensitivity, adequate selectivity with good tolerance to foreign ions, and was applied to the determination of trace amounts of Pb(II) in refill solutions for e-cigarettes with satisfactory results validated by ICP-MS. The proposed method represents an innovative application of coacervation processes and of paper filters to solid surface fluorescence methodology. Copyright © 2015 Elsevier B.V. All rights reserved.

The Iron-Iron Carbide Phase Diagram: A Practical Guide to Some Descriptive Solid State Chemistry.

ERIC Educational Resources Information Center

Long, Gary J.; Leighly, H. P., Jr.

1982-01-01

Discusses the solid state chemistry of iron and steel in terms of the iron-iron carbide phase diagram. Suggests that this is an excellent way of introducing the phase diagram (equilibrium diagram) to undergraduate students while at the same time introducing the descriptive solid state chemistry of iron and steel. (Author/JN)

Sensitivity of solid explosives: Minimum energy of a dangerous impact

NASA Technical Reports Server (NTRS)

Afanasyev, G. T.

1986-01-01

A method which uses initiating explosives for determining the sensitivity of solid explosives is described. The energy index of sensitivity is determined by the mechanical properties of the explosives. The results of the calculations are discussed.

An Investigation into the Polymorphism and Crystallization of Levetiracetam and the Stability of its Solid Form.

PubMed

Xu, Kailin; Xiong, Xinnuo; Guo, Liuqi; Wang, Lili; Li, Shanshan; Tang, Peixiao; Yan, Jin; Wu, Di; Li, Hui

2015-12-01

Levetiracetam (LEV) crystals were prepared using different solvents at different temperatures. The LEV crystals were systematically characterized by X-ray powder diffraction (XRPD) and morphological analysis. The results indicated that many kinds of crystal habits exist in a solid form of LEV. To investigate the effects of LEV concentration, crystallization temperature, and crystallization type on crystallization and solid phase transformation of LEV, multiple methods were performed for LEV aqueous solution to determine if a new solid form exists in solid-state LEV. However, XRPD data demonstrate that the LEV solid forms possess same spatial arrangements that are similar to the original solid form. This result indicates that the LEV concentration, crystallization temperature, and crystallization type in aqueous solution have no influence on the crystallization and solid phase transformation of LEV. Moreover, crystallization by sublimation, melt cooling, and quench cooling, as well as mechanical effect, did not result in the formation of new LEV solid state. During melt cooling, the transformation of solid form LEV is a direct process from melting amorphous phase to the original LEV crystal phase, and the conversion rate is very quick. In addition, stability investigation manifested that LEV solid state is very stable under various conditions. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Determination of Chlorinated Hydrocarbons in Water Using Highly Sensitive Mid-Infrared Sensor Technology

NASA Astrophysics Data System (ADS)

Lu, Rui; Mizaikoff, Boris; Li, Wen-Wei; Qian, Chen; Katzir, Abraham; Raichlin, Yosef; Sheng, Guo-Ping; Yu, Han-Qing

2013-08-01

Chlorinated aliphatic hydrocarbons and chlorinated aromatic hydrocarbons (CHCs) are toxic and carcinogenic contaminants commonly found in environmental samples, and efficient online detection of these contaminants is still challenging at the present stage. Here, we report an advanced Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) sensor for in-situ and simultaneous detection of multiple CHCs, including monochlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, trichloroethylene, perchloroethylene, and chloroform. The polycrystalline silver halide sensor fiber had a unique integrated planar-cylindric geometry, and was coated with an ethylene/propylene copolymer membrane to act as a solid phase extractor, which greatly amplified the analytical signal and contributed to a higher detection sensitivity compared to the previously reported sensors. This system exhibited a high detection sensitivity towards the CHCs mixture at a wide concentration range of 5~700 ppb. The FTIR-ATR sensor described in this study has a high potential to be utilized as a trace-sensitive on-line device for water contamination monitoring.

Determination of Chlorinated Hydrocarbons in Water Using Highly Sensitive Mid-Infrared Sensor Technology

PubMed Central

Lu, Rui; Mizaikoff, Boris; Li, Wen-Wei; Qian, Chen; Katzir, Abraham; Raichlin, Yosef; Sheng, Guo-Ping; Yu, Han-Qing

2013-01-01

Chlorinated aliphatic hydrocarbons and chlorinated aromatic hydrocarbons (CHCs) are toxic and carcinogenic contaminants commonly found in environmental samples, and efficient online detection of these contaminants is still challenging at the present stage. Here, we report an advanced Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) sensor for in-situ and simultaneous detection of multiple CHCs, including monochlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, trichloroethylene, perchloroethylene, and chloroform. The polycrystalline silver halide sensor fiber had a unique integrated planar-cylindric geometry, and was coated with an ethylene/propylene copolymer membrane to act as a solid phase extractor, which greatly amplified the analytical signal and contributed to a higher detection sensitivity compared to the previously reported sensors. This system exhibited a high detection sensitivity towards the CHCs mixture at a wide concentration range of 5~700 ppb. The FTIR-ATR sensor described in this study has a high potential to be utilized as a trace-sensitive on-line device for water contamination monitoring. PMID:23982222

Determination of chlorinated hydrocarbons in water using highly sensitive mid-infrared sensor technology.

PubMed

Lu, Rui; Mizaikoff, Boris; Li, Wen-Wei; Qian, Chen; Katzir, Abraham; Raichlin, Yosef; Sheng, Guo-Ping; Yu, Han-Qing

2013-01-01

Chlorinated aliphatic hydrocarbons and chlorinated aromatic hydrocarbons (CHCs) are toxic and carcinogenic contaminants commonly found in environmental samples, and efficient online detection of these contaminants is still challenging at the present stage. Here, we report an advanced Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) sensor for in-situ and simultaneous detection of multiple CHCs, including monochlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, trichloroethylene, perchloroethylene, and chloroform. The polycrystalline silver halide sensor fiber had a unique integrated planar-cylindric geometry, and was coated with an ethylene/propylene copolymer membrane to act as a solid phase extractor, which greatly amplified the analytical signal and contributed to a higher detection sensitivity compared to the previously reported sensors. This system exhibited a high detection sensitivity towards the CHCs mixture at a wide concentration range of 5~700 ppb. The FTIR-ATR sensor described in this study has a high potential to be utilized as a trace-sensitive on-line device for water contamination monitoring.

Quantitative mass spectrometry methods for pharmaceutical analysis

PubMed Central

Loos, Glenn; Van Schepdael, Ann

2016-01-01

Quantitative pharmaceutical analysis is nowadays frequently executed using mass spectrometry. Electrospray ionization coupled to a (hybrid) triple quadrupole mass spectrometer is generally used in combination with solid-phase extraction and liquid chromatography. Furthermore, isotopically labelled standards are often used to correct for ion suppression. The challenges in producing sensitive but reliable quantitative data depend on the instrumentation, sample preparation and hyphenated techniques. In this contribution, different approaches to enhance the ionization efficiencies using modified source geometries and improved ion guidance are provided. Furthermore, possibilities to minimize, assess and correct for matrix interferences caused by co-eluting substances are described. With the focus on pharmaceuticals in the environment and bioanalysis, different separation techniques, trends in liquid chromatography and sample preparation methods to minimize matrix effects and increase sensitivity are discussed. Although highly sensitive methods are generally aimed for to provide automated multi-residue analysis, (less sensitive) miniaturized set-ups have a great potential due to their ability for in-field usage. This article is part of the themed issue ‘Quantitative mass spectrometry’. PMID:27644982

Building of Equations of State with Numerous Phase Transitions — Application to Bismuth

NASA Astrophysics Data System (ADS)

Heuzé, Olivier

2006-07-01

We propose an algorithm to build complete equation of state EOS including several solid/solid or solid/liquid phase transitions. Each phase has its own EOS and independent parameters. The phase diagram is deduced from the thermodynamic equilibrium assumption. Until now, such an approach was used in simple cases and limited to 2 or 3 phases. We have applied it in the general case to bismuth for which up to 13 phases have been identified. This study shows the great influence of binary mixtures and triple points properties in released isentropes after shock waves.

Density-functional theory for fluid-solid and solid-solid phase transitions.

PubMed

Bharadwaj, Atul S; Singh, Yashwant

2017-03-01

We develop a theory to describe solid-solid phase transitions. The density functional formalism of classical statistical mechanics is used to find an exact expression for the difference in the grand thermodynamic potentials of the two coexisting phases. The expression involves both the symmetry conserving and the symmetry broken parts of the direct pair correlation function. The theory is used to calculate phase diagram of systems of soft spheres interacting via inverse power potentials u(r)=ε(σ/r)^{n}, where parameter n measures softness of the potential. We find that for 1/n<0.154 systems freeze into the face centered cubic (fcc) structure while for 1/n≥0.154 the body-centred-cubic (bcc) structure is preferred. The bcc structure transforms into the fcc structure upon increasing the density. The calculated phase diagram is in good agreement with the one found from molecular simulations.

Multiplexed interfacial transduction of nucleic acid hybridization using a single color of immobilized quantum dot donor and two acceptors in fluorescence resonance energy transfer.

PubMed

Algar, W Russ; Krull, Ulrich J

2010-01-01

A multiplexed solid-phase assay for the detection of nucleic acid hybridization was developed on the basis of a single color of immobilized CdSe/ZnS quantum dot (QD) as a donor in fluorescence resonance energy transfer (FRET). This work demonstrated that two channels of detection did not necessitate two different QD donors. Two probe oligonucleotides were coimmobilized on optical fibers modified with QDs, and a sandwich assay was used to associate the acceptor dyes with interfacial hybridization events without target labeling. FRET-sensitized acceptor emission provided an analytical signal that was concentration dependent down to 10 nM. Changes in the ratio of coimmobilized probe oligonucleotides were found to yield linear changes in the relative amounts of acceptor emission. These changes were compared to previous studies that used mixed films of two QD donors for two detection channels. The analysis indicated that probe dilution effects were primarily driven by changes in acceptor number density and that QD dilution effects or changes in mean donor-acceptor distance were secondary. Hybridization kinetics were found to be consistent between different ratios of coimmobilized probes, suggesting that hybridization in this type of system occurred via the accepted model for solid-phase hybridization, where adsorption and then diffusion at the solid interface drove hybridization.

Mass balance evaluation of polybrominated diphenyl ethers in landfill leachate and potential for transfer from e-waste.

PubMed

Danon-Schaffer, Monica N; Mahecha-Botero, Andrés; Grace, John R; Ikonomou, Michael

2013-09-01

Previous research on brominated flame retardants (BFRs), including polybrominated diphenyl ethers (PBDEs) has largely focussed on their concentrations in the environment and their adverse effects on human health. This paper explores their transfer from waste streams to water and soil. A comprehensive mass balance model is developed to track polybrominated diphenyl ethers (PBDEs), originating from e-waste and non-e-waste solids leaching from a landfill. Stepwise debromination is assumed to occur in three sub-systems (e-waste, aqueous leachate phase, and non-e-waste solids). Analysis of landfill samples and laboratory results from a solid-liquid contacting chamber are used to estimate model parameters to simulate an urban landfill system, for past and future scenarios. Sensitivity tests to key model parameters were conducted. Lower BDEs require more time to disappear than high-molecular weight PBDEs, since debromination takes place in a stepwise manner, according to the simplified reaction scheme. Interphase mass transfer causes the decay pattern to be similar in all three sub-systems. The aqueous phase is predicted to be the first sub-system to eliminate PBDEs if their input to the landfill were to be stopped. The non-e-waste solids would be next, followed by the e-waste sub-system. The model shows that mass transfer is not rate-limiting, but the evolution over time depends on the kinetic degradation parameters. Experimental scatter makes model testing difficult. Nevertheless, the model provides qualitative understanding of the influence of key variables. Copyright © 2013 Elsevier B.V. All rights reserved.

Effects of Chlorine Promoted Oxidation on Arsenic Release from Sulfide Minerals

NASA Astrophysics Data System (ADS)

West, N.; Schreiber, M.; Gotkowitz, M.

2007-12-01

High arsenic concentrations (>100 ppb) have been measured in wells completed in the Ordovician St. Peter sandstone aquifer of eastern Wisconsin. The primary source of arsenic is As-bearing sulfide minerals within the aquifer. Periodic disinfection of wells by chlorination may facilitate arsenic release to groundwater by increasing the rate of sulfide mineral oxidation. During typical well disinfection procedures, aquifer solids exposed along uncased portions of wells remain in direct contact with chlorine disinfection solutions for up to twenty-four hours. Due to the redox sensitivity of arsenic mobility in groundwater, it is important to evaluate the effect of repeatedly adding oxidizers to an arsenic impacted aquifer system. This study focuses on abiotic processes that mobilize arsenic from the solid phase during controlled exposure to chlorinated solutions. Two St. Peter samples with As concentrations of 21 and 674 ppm were selected for the experiments. Before reaction, the aquifer mineralogy is characterized using scanning electron microscopy (SEM) and electron microprobe analysis (EMPA). The samples are then reacted with solutions of 60 mg/L free chlorine, 1200 mg/L free chlorine, or nanopure water (control) at pH 7.0 and pH 8.5. These parameters represent typical solution chemistries present within the wells after disinfection. Solutions are sampled periodically during the experiments and analyzed for As, Fe, other trace metals such as Co, Mo, Cr, and Ni, and sulfate. Analysis of the post-reaction solids using SEM, EMPA, laser ablation ICP-MS and Raman techniques are used to document the changes in mineralogy due to chlorination and to document which solid phases contain As.

Preconcentration of Trace Neonicotinoid Insecticide Residues Using Vortex-Assisted Dispersive Micro Solid-Phase Extraction with Montmorillonite as an Efficient Sorbent.

PubMed

Moyakao, Khwankaew; Santaladchaiyakit, Yanawath; Srijaranai, Supalax; Vichapong, Jitlada

2018-04-11

In this work, we investigated montmorillonite for adsorption of neonicotinoid insecticides in vortex-assisted dispersive micro-solid phase extraction (VA-d-μ-SPE). High-performance liquid chromatography with photodiode array detection was used for quantification and determination of neonicotinoid insecticide residues, including thiamethoxam, clothianidin, imidacloprid, acetamiprid, and thiacloprid. In this method, the solid sorbent was dispersed into the aqueous sample solution and vortex agitation was performed to accelerate the extraction process. Finally, the solution was filtered from the solid sorbent with a membrane filter. The parameters affecting the extraction efficiency of the proposed method were optimized, such as amount of sorbent, sample volume, salt addition, type and volume of extraction solvent, and vortex time. The adsorbing results show that montmorillonite could be reused at least 4 times and be used as an effective adsorbent for rapid extraction/preconcentration of neonicotinoid insecticide residues. Under optimum conditions, linear dynamic ranges were achieved between 0.5 and 1000 ng mL -1 with a correlation of determination ( R² ) greater than 0.99. Limit of detection (LOD) ranged from 0.005 to 0.065 ng mL -1 , while limit of quantification (LOQ) ranged from 0.008 to 0.263 ng mL -1 . The enrichment factor (EF) ranged from 8 to 176-fold. The results demonstrated that the proposed method not only provided a more simple and sensitive method, but also can be used as a powerful alternative method for the simultaneous determination of insecticide residues in natural surface water and fruit juice samples.

Two-phase anaerobic digestion of vegetable market waste fraction of municipal solid waste and development of improved technology for phase separation in two-phase reactor.

PubMed

Majhi, Bijoy Kumar; Jash, Tushar

2016-12-01

Biogas production from vegetable market waste (VMW) fraction of municipal solid waste (MSW) by two-phase anaerobic digestion system should be preferred over the single-stage reactors. This is because VMW undergoes rapid acidification leading to accumulation of volatile fatty acids and consequent low pH resulting in frequent failure of digesters. The weakest part in the two-phase anaerobic reactors was the techniques applied for solid-liquid phase separation of digestate in the first reactor where solubilization, hydrolysis and acidogenesis of solid organic waste occur. In this study, a two-phase reactor which consisted of a solid-phase reactor and a methane reactor was designed, built and operated with VMW fraction of Indian MSW. A robust type filter, which is unique in its implementation method, was developed and incorporated in the solid-phase reactor to separate the process liquid produced in the first reactor. Experiments were carried out to assess the long term performance of the two-phase reactor with respect to biogas production, volatile solids reduction, pH and number of occurrence of clogging in the filtering system or choking in the process liquid transfer line. The system performed well and was operated successfully without the occurrence of clogging or any other disruptions throughout. Biogas production of 0.86-0.889m 3 kg -1 VS, at OLR of 1.11-1.585kgm -3 d -1 , were obtained from vegetable market waste, which were higher than the results reported for similar substrates digested in two-phase reactors. The VS reduction was 82-86%. The two-phase anaerobic digestion system was demonstrated to be stable and suitable for the treatment of VMW fraction of MSW for energy generation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Thermodynamic Investigation of the Effect of Interface Curvature on the Solid-Liquid Equilibrium and Eutectic Point of Binary Mixtures.

PubMed

Liu, Fanghui; Zargarzadeh, Leila; Chung, Hyun-Joong; Elliott, Janet A W

2017-10-12

Thermodynamic phase behavior is affected by curved interfaces in micro- and nanoscale systems. For example, capillary freezing point depression is associated with the pressure difference between the solid and liquid phases caused by interface curvature. In this study, the thermal, mechanical, and chemical equilibrium conditions are derived for binary solid-liquid equilibrium with a curved solid-liquid interface due to confinement in a capillary. This derivation shows the equivalence of the most general forms of the Gibbs-Thomson and Ostwald-Freundlich equations. As an example, the effect of curvature on solid-liquid equilibrium is explained quantitatively for the water/glycerol system. Considering the effect of a curved solid-liquid interface, a complete solid-liquid phase diagram is developed over a range of concentrations for the water/glycerol system (including the freezing of pure water or precipitation of pure glycerol depending on the concentration of the solution). This phase diagram is compared with the traditional phase diagram in which the assumption of a flat solid-liquid interface is made. We show the extent to which nanoscale interface curvature can affect the composition-dependent freezing and precipitating processes, as well as the change in the eutectic point temperature and concentration with interface curvature. Understanding the effect of curvature on solid-liquid equilibrium in nanoscale capillaries has applications in the food industry, soil science, cryobiology, nanoporous materials, and various nanoscience fields.

Suppressing the cellular breakdown in silicon supersaturated with titanium

NASA Astrophysics Data System (ADS)

Liu, Fang; Prucnal, S.; Hübner, R.; Yuan, Ye; Skorupa, W.; Helm, M.; Zhou, Shengqiang

2016-06-01

Hyper doping Si with up to 6 at.% Ti in solid solution was performed by ion implantation followed by pulsed laser annealing and flash lamp annealing. In both cases, the implanted Si layer can be well recrystallized by liquid phase epitaxy and solid phase epitaxy, respectively. Cross-sectional transmission electron microscopy of Ti-implanted Si after liquid phase epitaxy shows the so-called growth interface breakdown or cellular breakdown owing to the occurrence of constitutional supercooling in the melt. The appearance of cellular breakdown prevents further recrystallization. However, the out-diffusion and cellular breakdown can be effectively suppressed by solid phase epitaxy during flash lamp annealing due to the high velocity of amorphous-crystalline interface and the low diffusion velocity for Ti in the solid phase.

An Integrated Instrumentation System for Velocity, Concentration and Mass Flow Rate Measurement of Solid Particles Based on Electrostatic and Capacitance Sensors.

PubMed

Li, Jian; Kong, Ming; Xu, Chuanlong; Wang, Shimin; Fan, Ying

2015-12-10

The online and continuous measurement of velocity, concentration and mass flow rate of pneumatically conveyed solid particles for the high-efficiency utilization of energy and raw materials has become increasingly significant. In this paper, an integrated instrumentation system for the velocity, concentration and mass flow rate measurement of dense phase pneumatically conveyed solid particles based on electrostatic and capacitance sensorsis developed. The electrostatic sensors are used for particle mean velocity measurement in combination with the cross-correlation technique, while the capacitance sensor with helical surface-plate electrodes, which has relatively homogeneous sensitivity distribution, is employed for the measurement of particle concentration and its capacitance is measured by an electrostatic-immune AC-based circuit. The solid mass flow rate can be further calculated from the measured velocity and concentration. The developed instrumentation system for velocity and concentration measurement is verified and calibrated on a pulley rig and through static experiments, respectively. Finally the system is evaluated with glass beads on a gravity-fed rig. The experimental results demonstrate that the system is capable of the accurate solid mass flow rate measurement, and the relative error is within -3%-8% for glass bead mass flow rates ranging from 0.13 kg/s to 0.9 kg/s.

Direct measurement of the glucuronide conjugate of 1-hydroxypyrene in human urine by using liquid chromatography with tandem mass spectrometry.

PubMed

Kakimoto, Kensaku; Toriba, Akira; Ohno, Takanori; Ueno, Mariko; Kameda, Takayuki; Tang, Ning; Hayakawa, Kazuichi

2008-05-15

To evaluate human exposure to polycyclic aromatic hydrocarbons (PAHs), we developed a rapid, simple and sensitive method for determining 1-hydroxypyrene-glucuronide (1-OHP-G) in human urine. To improve precision, a deuterated glucuronide was used as an internal standard. The method requires only 1 mL of urine. The urine was treated with a mixed-mode anion-exchange and reversed-phase solid-phase extraction cartridge (Oasis MAX). The analytes were analyzed with a C(18) reversed-phase column with a gradient elution, followed by tandem mass spectrometry with electrospray ionization in negative ion mode. The detection limit of 1-OHP-G (corresponding to a signal-to-noise ratio of 3) was 0.13 fmol/injection. Urinary concentrations of 1-OHP-G determined by this method were strongly correlated (r(2)=0.961) with concentrations of 1-hydroxypyrene by conventional HPLC with fluorescence detection.

Determination of flunixin residues in bovine muscle tissue by liquid chromatography with UV detection.

PubMed

Asea, P A; Patterson, J R; Korsrud, G O; Dowling, P M; Boison, J O

2001-01-01

A new and sensitive liquid chromatography-ultra violet method with a detection limit of 6 ng/g (ppb) and a limit of quantification of 15 ng/g was developed for the determination of flunixin residues in bovine muscle tissue. Flunixin in homogenized animal tissue was extracted with acetonitrile after enzyme digestion. The tissue digest (extract) was then cleaned up on a solid-phase extraction cartridge and eluted with acidified hexane. After the eluate was evaporated to dryness under nitrogen at 55 degrees C, the residue was reconstituted in 1 mL mobile phase solution and analyzed by reversed-phase gradient chromatography with UV detection at 285 nm. The method was then applied in a survey study of slaughter animals to determine whether flunixin is being used in an off-label manner for veal and beef production in Canada.

A High-Throughput Process for the Solid-Phase Purification of Synthetic DNA Sequences

PubMed Central

Grajkowski, Andrzej; Cieślak, Jacek; Beaucage, Serge L.

2017-01-01

An efficient process for the purification of synthetic phosphorothioate and native DNA sequences is presented. The process is based on the use of an aminopropylated silica gel support functionalized with aminooxyalkyl functions to enable capture of DNA sequences through an oximation reaction with the keto function of a linker conjugated to the 5′-terminus of DNA sequences. Deoxyribonucleoside phosphoramidites carrying this linker, as a 5′-hydroxyl protecting group, have been synthesized for incorporation into DNA sequences during the last coupling step of a standard solid-phase synthesis protocol executed on a controlled pore glass (CPG) support. Solid-phase capture of the nucleobase- and phosphate-deprotected DNA sequences released from the CPG support is demonstrated to proceed near quantitatively. Shorter than full-length DNA sequences are first washed away from the capture support; the solid-phase purified DNA sequences are then released from this support upon reaction with tetra-n-butylammonium fluoride in dry dimethylsulfoxide (DMSO) and precipitated in tetrahydrofuran (THF). The purity of solid-phase-purified DNA sequences exceeds 98%. The simulated high-throughput and scalability features of the solid-phase purification process are demonstrated without sacrificing purity of the DNA sequences. PMID:28628204

Nanostructured lipid carriers: effect of solid phase fraction and distribution on the release of encapsulated materials.

PubMed

Dan, Nily

2014-11-25

Emulsions, solid lipid nanoparticles (SLN), and nanostructured lipid carriers (NLC) containing a mix of liquid and solid domains are of interest as encapsulation vehicles for hydrophobic compounds. Studies of the release rate from these particles yield contradictory results: Some find that increasing the fraction of solid phase increases the rate of release and others the opposite. In this paper we study the release of encapsulated materials from lipid-based nanoparticles using Monte Carlo simulations. We find that, quite surprisingly, the release rate is largely insensitive to the size of solid domains or the fraction of solid phase. However, the distribution of the domains significantly affects the rate of release: Solid domains located at the interface with the surrounding solution inhibit transport, while nanoparticles where the solid domains are concentrated in the center enhance it. The latter can lead to release rates in NLCs that are faster than in the equivalent emulsions. We conclude that controlling the release rate from NLCs requires the ability to determine the location and distribution of the solid phase, which may be achieved through choice of the surfactants stabilizing the particles, incorporation of nucleation sites, and/or the cooling rates and temperatures.

Solid phase stability of molybdenum under compression: Sound velocity measurements and first-principles calculations

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

Zhang, Xiulu; Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology, 621010 Mianyang, Sichuan; Liu, Zhongli

2015-02-07

The high-pressure solid phase stability of molybdenum (Mo) has been the center of a long-standing controversy on its high-pressure melting. In this work, experimental and theoretical researches have been conducted to check its solid phase stability under compression. First, we performed sound velocity measurements from 38 to 160 GPa using the two-stage light gas gun and explosive loading in backward- and forward-impact geometries, along with the high-precision velocity interferometry. From the sound velocities, we found no solid-solid phase transition in Mo before shock melting, which does not support the previous solid-solid phase transition conclusion inferred from the sharp drops of themore » longitudinal sound velocity [Hixson et al., Phys. Rev. Lett. 62, 637 (1989)]. Then, we searched its structures globally using the multi-algorithm collaborative crystal structure prediction technique combined with the density functional theory. By comparing the enthalpies of body centered cubic structure with those of the metastable structures, we found that bcc is the most stable structure in the range of 0–300 GPa. The present theoretical results together with previous ones greatly support our experimental conclusions.« less

Solid- and vapor-phase antimicrobial activities of six essential oils: susceptibility of selected foodborne bacterial and fungal strains.

PubMed

López, P; Sánchez, C; Batlle, R; Nerín, C

2005-08-24

The antimicrobial activity of essential oils (EOs) of cinnamon (Cinnamon zeylanicum), clove (Syzygium aromaticum), basil (Ocimum basillicum), rosemary (Rosmarinus officinalis), dill (Anethum graveolens), and ginger (Zingiber officinalis) was evaluated over a range of concentrations in two types of contact tests (solid and vapor diffusion). The EOs were tested against an array of four Gram-positive bacteria (Staphylococcus aureus, Bacillus cereus, Enterococcus faecalis, and Listeria monocytogenes), four Gram-negative bacteria (Escherichia coli, Yersinia enterocolitica, Salmonella choleraesuis, and Pseudomonas aeruginosa), and three fungi (a yeast, Candida albicans, and two molds, Penicillium islandicum and Aspergillus flavus). The rationale for this work was to test the possibility of creating a protective atmosphere by using natural compounds that could extend the shelf life of packaged foodstuffs while minimizing organoleptic alterations. In the solid diffusion tests, cinnamon and clove gave the strongest (and very similar) inhibition, followed by basil and rosemary, with dill and ginger giving the weakest inhibition. The fungi were the most sensitive microorganisms, followed by the Gram-positive bacterial strains. The Gram-negative strain P. aeruginosa was the least inhibited. The composition of the atmosphere generated by the EOs, and their minimum inhibitory concentrations (MICs), were determined using a disk volatilization method, in which no inhibition from rosemary or basil was observed. Cinnamon and clove, once again, gave similar results for every microorganism. As a general rule, MIC (fungi) < MIC (bacteria) with no clear differences between Gram-positive or -negative strains except for P. aeruginosa, which was not inhibited by any of the EOs in the vapor phase. The atmosphere generated from the EOs was analyzed by means of solid-phase microextraction combined with gas chromatography-ion trap mass spectrometry. Differences among the volatiles in the EOs, which may be responsible for the differences in their antimicrobial performances, were found.

Characterization of the temperature and humidity-dependent phase diagram of amorphous nanoscale organic aerosols.

PubMed

Rothfuss, Nicholas E; Petters, Markus D

2017-03-01

Atmospheric aerosols can exist in amorphous semi-solid or glassy phase states. These states are determined by the temperature (T) and relative humidity (RH). New measurements of viscosity for amorphous semi-solid nanometer size sucrose particles as a function of T and RH are reported. Viscosity is measured by inducing coagulation between two particles and probing the thermodynamic states that induce the particle to relax into a sphere. It is shown that the glass transition temperature can be obtained by extrapolation to 10 12 Pa s from the measured temperature-dependent viscosity in the 10 6 to 10 7 Pa s range. The experimental methodology was refined to allow isothermal probing of RH dependence and to increase the range of temperatures over which the dry temperature dependence can be studied. Several experiments where one monomer was sodium dodecyl sulfate (SDS), which remains solid at high RH, are also reported. These sucrose-SDS dimers were observed to relax into a sphere at T and RH similar to those observed in sucrose-sucrose dimers, suggesting that amorphous sucrose will flow over an insoluble particle at a viscosity similar to that characteristic of coalescence between two sucrose particles. Possible physical and analytical implications of this observation are considered. The data reported here suggest that semi-solid viscosity between 10 4 and 10 12 Pa s can be modelled over a wide range of T and RH using an adapted Vogel-Fulcher-Tammann equation and the Gordon-Taylor mixing rule. Sensitivity of modelled viscosity to variations in dry glass transition temperature, Gordon-Taylor constant, and aerosol hygroscopicity are explored, along with implications for atmospheric processes such as ice nucleation of glassy organic aerosols in the upper free troposphere. The reported measurement and modelling framework provides a template for characterizing the phase diagram of other amorphous aerosol systems, including secondary organic aerosols.

Communication: phase transitions, criticality, and three-phase coexistence in constrained cell models.

PubMed

Nayhouse, Michael; Kwon, Joseph Sang-Il; Orkoulas, G

2012-05-28

In simulation studies of fluid-solid transitions, the solid phase is usually modeled as a constrained system in which each particle is confined to move in a single Wigner-Seitz cell. The constrained cell model has been used in the determination of fluid-solid coexistence via thermodynamic integration and other techniques. In the present work, the phase diagram of such a constrained system of Lennard-Jones particles is determined from constant-pressure simulations. The pressure-density isotherms exhibit inflection points which are interpreted as the mechanical stability limit of the solid phase. The phase diagram of the constrained system contains a critical and a triple point. The temperature and pressure at the critical and the triple point are both higher than those of the unconstrained system due to the reduction in the entropy caused by the single occupancy constraint.

Modeling of Shock Waves with Multiple Phase Transitions in Condensed Materials

NASA Astrophysics Data System (ADS)

Missonnier, Marc; Heuzé, Olivier

2006-07-01

When a shock wave crosses a solid material and subjects it to solid-solid or solid-liquid phase transition, related phenomena occur: shock splitting, and the corresponding released shock wave after reflection. Modelling of these phenomena raises physical and numerical issues. After shock loading, such materials can reach different kinds of states: single-phase states, binary-phase states, and triple points. The thermodynamic path can be studied and easily understood in the (V,E) or (V,S) planes. In the case of 3 phase tin (β,γ, and liquid) submitted to shock waves, seven states can occur: β,γ, liquid, β-γ, β-liquid, γ-liquid, and β-γ-liquid. After studying the thermodynamic properties with a complete 3-phase Equation of State, we show the existence of these seven states with a hydrodynamic simulation.

Optimization of the β-Elimination/Michael Addition Chemistry on Reversed-Phase Supports for Mass Spectrometry Analysis of O-Linked Protein Modifications

PubMed Central

Nika, Heinz; Nieves, Edward; Hawke, David H.; Angeletti, Ruth Hogue

2013-01-01

We previously adapted the β-elimination/Michael addition chemistry to solid-phase derivatization on reversed-phase supports, and demonstrated the utility of this reaction format to prepare phosphoseryl peptides in unfractionated protein digests for mass spectrometric identification and facile phosphorylation-site determination. Here, we have expanded the use of this technique to β-N-acetylglucosamine peptides, modified at serine/threonine, phosphothreonyl peptides, and phosphoseryl/phosphothreonyl peptides, followed in sequence by proline. The consecutive β-elimination with Michael addition was adapted to optimize the solid-phase reaction conditions for throughput and completeness of derivatization. The analyte remained intact during derivatization and was recovered efficiently from the silica-based, reversed-phase support with minimal sample loss. The general use of the solid-phase approach for enzymatic dephosphorylation was demonstrated with phosphoseryl and phosphothreonyl peptides and was used as an orthogonal method to confirm the identity of phosphopeptides in proteolytic mixtures. The solid-phase approach proved highly suitable to prepare substrates from low-level amounts of protein digests for phosphorylation-site determination by chemical-targeted proteolysis. The solid-phase protocol provides for a simple, robust, and efficient tool to prepare samples for phosphopeptide identification in MALDI mass maps of unfractionated protein digests, using standard equipment available in most biological laboratories. The use of a solid-phase analytical platform is expected to be readily expanded to prepare digest from O-glycosylated- and O-sulfonated proteins for mass spectrometry-based structural characterization. PMID:23997661

Equations of State and Phase Diagrams of Ammonia

ERIC Educational Resources Information Center

Glasser, Leslie

2009-01-01

We present equations of state relating the phases and a three-dimensional phase diagram for ammonia with its solid, liquid, and vapor phases, based on fitted authentic experimental data and including recent information on the high-pressure solid phases. This presentation follows similar articles on carbon dioxide and water published in this…

Topology optimisation for natural convection problems

NASA Astrophysics Data System (ADS)

Alexandersen, Joe; Aage, Niels; Andreasen, Casper Schousboe; Sigmund, Ole

2014-12-01

This paper demonstrates the application of the density-based topology optimisation approach for the design of heat sinks and micropumps based on natural convection effects. The problems are modelled under the assumptions of steady-state laminar flow using the incompressible Navier-Stokes equations coupled to the convection-diffusion equation through the Boussinesq approximation. In order to facilitate topology optimisation, the Brinkman approach is taken to penalise velocities inside the solid domain and the effective thermal conductivity is interpolated in order to accommodate differences in thermal conductivity of the solid and fluid phases. The governing equations are discretised using stabilised finite elements and topology optimisation is performed for two different problems using discrete adjoint sensitivity analysis. The study shows that topology optimisation is a viable approach for designing heat sink geometries cooled by natural convection and micropumps powered by natural convection.

Offline solid-phase extraction for preconcentration of pharmaceuticals and personal care products in environmental water and their simultaneous determination using the reversed phase high-performance liquid chromatography method.

PubMed

G Archana; Dhodapkar, Rita; Kumar, Anupama

2016-09-01

The present study reports a precise and simple offline solid-phase extraction (SPE) coupled with reversed-phase high-performance liquid chromatography (RP-HPLC) method for the simultaneous determination of five representative and commonly present pharmaceuticals and personal care products (PPCPs), a new class of emerging pollutants in the aquatic environment. The target list of analytes including ciprofloxacin, acetaminophen, caffeine benzophenone and irgasan were separated by a simple HPLC method. The column used was a reversed-phase C18 column, and the mobile phase was 1 % acetic acid and methanol (20:80 v/v) under isocratic conditions, at a flow rate of 1 mL min(-1). The analytes were separated and detected within 15 min using the photodiode array detector (PDA). The linearity of the calibration curves were obtained with correlation coefficients 0.98-0.99.The limit of detection (LOD), limit of quantification (LOQ), precision, accuracy and ruggedness demonstrated the reproducibility, specificity and sensitivity of the developed method. Prior to the analysis, the SPE was performed using a C18 cartridge to preconcentrate the targeted analytes from the environmental water samples. The developed method was applied to evaluate and fingerprint PPCPs in sewage collected from a residential engineering college campus, polluted water bodies such as Nag river and Pili river and the influent and effluent samples from a sewage treatment plant (STP) situated at Nagpur city, in the peak summer season. This method is useful for estimation of pollutants present in microquantities in the surface water bodies and treated sewage as compared to nanolevel pollutants detected by mass spectrometry (MS) detectors.

Development of water-phase derivatization followed by solid-phase microextraction and gas chromatography/mass spectrometry for fast determination of valproic acid in human plasma.

PubMed

Deng, Chunhui; Li, Ning; Ji, Jie; Yang, Bei; Duan, Gengli; Zhang, Xiangmin

2006-01-01

In this study, a simple, rapid, and sensitive method was developed and validated for the quantification of valproic acid (VPA), an antiepileptic drug, in human plasma, which was based on water-phase derivatization followed by headspace solid-phase microextraction (HS-SPME) and gas chromatography/mass spectrometry (GC/MS). In the proposed method, VPA in plasma was rapidly derivatized with a mixture of isobutyl chloroformate, ethanol and pyridine under mild conditions (room temperature, aqueous medium), and the VPA ethyl ester formed was headspace-extracted and simultaneously concentrated using the SPME technique. Finally, the analyte extracted on SPME fiber was analyzed by GC/MS. The experimental parameters and method validations were studied. The optimal conditions were obtained: PDMS fiber, stirring rate of 1100 rpm, sample temperature of 80 degrees C, extraction time of 20 min, NaCl concentration of 30%. The proposed method had a limit of quantification (0.3 microg/mL), good recovery (89-97%) and precision (RSD value less than 10%). Because the proposed method combined a rapid water-phase derivatization with a fast, simple and solvent-free sample extraction and concentration technique of SPME, the sample preparation time was less than 25 min. This much shortens the whole analysis time of VPA in plasma. The validated method has been successfully used to analyze VPA in human plasma samples for application in pharmacokinetic studies. All these results show that water-phase derivatization followed by HS-SPME and GC/MS is an alternative and powerful method for fast determination of VPA in biological fluids. Copyright 2006 John Wiley & Sons, Ltd.

Phase Composition and Disorder in La2(Sn,Ti)2O7 Ceramics: New Insights from NMR Crystallography.

PubMed

Fernandes, Arantxa; McKay, David; Sneddon, Scott; Dawson, Daniel M; Lawson, Sebastian; Veazey, Richard; Whittle, Karl R; Ashbrook, Sharon E

2016-09-15

An NMR crystallographic approach, involving the combination of 119 Sn NMR spectroscopy, XRD, and DFT calculations, is demonstrated for the characterization of La 2 Sn 2- x Ti x O 7 ceramics. A phase change from pyrochlore (La 2 Sn 2 O 7 ) to a layered perovskite phase (La 2 Ti 2 O 7 ) is predicted (by radius ratio rules) to occur when x ≈ 0.95. However, the sensitivity of NMR spectroscopy to the local environment is able to reveal a significant two-phase region is present, extending from x = 1.8 to ∼0.2, with limited solid solution at the two extremes, in broad agreement with powder XRD measurements. DFT calculations reveal that there is preferential site substitution of Sn in La 2 Ti 2 O 7 , with calculated shifts for Sn substitution onto Ti1 and Ti2 sites (in the "bulk" perovskite layers) in better agreement with experiment than those for Ti3 and Ti4 ("edge" sites). Substitution onto these two sites also produces structural models with lower relative enthalpy. As the Sn content decreases, there is a further preference for substitution onto Sn2. In contrast, the relative intensities of the spectral resonances suggest that Ti substitution into the pyrochlore phase is random, although only a limited solid solution is observed (up to ∼7% Ti). DFT calculations predict very similar 119 Sn shifts for Sn substitution into the two proposed models of La 2 Ti 2 O 7 (monoclinic ( P 2 1 ) and orthorhombic ( Pna 2 1 )), indicating it is not possible to distinguish between them. However, the relative energy of the Sn-substituted orthorhombic phase was higher than that of substituted monoclinic cells, suggesting that the latter is the more likely structure.

Numerical Computation of Flame Spread over a Thin Solid in Forced Concurrent Flow with Gas-phase Radiation

NASA Technical Reports Server (NTRS)

Jiang, Ching-Biau; T'ien, James S.

1994-01-01

Excerpts from a paper describing the numerical examination of concurrent-flow flame spread over a thin solid in purely forced flow with gas-phase radiation are presented. The computational model solves the two-dimensional, elliptic, steady, and laminar conservation equations for mass, momentum, energy, and chemical species. Gas-phase combustion is modeled via a one-step, second order finite rate Arrhenius reaction. Gas-phase radiation considering gray non-scattering medium is solved by a S-N discrete ordinates method. A simplified solid phase treatment assumes a zeroth order pyrolysis relation and includes radiative interaction between the surface and the gas phase.

Phase III gross solids removal devices pilot study, 2002-2005.

DOT National Transportation Integrated Search

2005-12-01

The objective of the Phase III Gross Solids Removal Devices (GSRDs) Pilot study was to : evaluate the performance of non-proprietary devices that can capture gross solids and that can be : incorporated into existing highway drainage systems or implem...

Three-phase boundary length in solid-oxide fuel cells: A mathematical model

NASA Astrophysics Data System (ADS)

Janardhanan, Vinod M.; Heuveline, Vincent; Deutschmann, Olaf

A mathematical model to calculate the volume specific three-phase boundary length in the porous composite electrodes of solid-oxide fuel cell is presented. The model is exclusively based on geometrical considerations accounting for porosity, particle diameter, particle size distribution, and solids phase distribution. Results are presented for uniform particle size distribution as well as for non-uniform particle size distribution.

Platanus acerifolia pollinosis and food allergy.

PubMed

Enrique, E; Cisteró-Bahíma, A; Bartolomé, B; Alonso, R; San Miguel-Moncín, M M; Bartra, J; Martínez, A

2002-04-01

In Mediterranean areas, oral allergy syndrome (OAS) occurs independently of an associated birch pollinosis; moreover, on occasions it presents with no other associated pollinosis. The aim of this study was to assess the possible association of OAS with Platanus acerifolia pollinosis. We evaluated consecutive patients seen for pollinosis in an allergy department. Seven hundred and twenty patients were selected on the basis of seasonal or perennial rhinitis, or asthma, or both. Respiratory and food allergies were studied in all patients. Clinical history was recorded and examinations and skin prick tests were performed with a battery of available common inhalant allergens and plant-derived food allergens. Specific IgE levels to P. acerifolia pollen extract and food allergens tested were measured. Molecular masses of the IgE-binding proteins and cross-reactivity among the P. acerifolia pollen and different food extracts were also determined. Of the 720 patients evaluated, 61 (8.48%) were sensitized to P. acerifolia pollen. Food allergy was observed in 32 (52.45%) of the 61 patients sensitized to P. acerifolia pollen. Food allergens most frequently implicated were hazelnuts, peach, apple, peanuts, maize, chickpea and lettuce. Enzyme allergosorbent (EAST)-inhibition showed high inhibition values when P. acerifolia pollen extract was used as free phase. On the contrary low inhibition was observed when plant-derived food allergens were used as free phase and P. acerifolia pollen extract as solid phase. Cross-reactivity was observed among P. acerifolia pollen and plant-derived foods. OAS in these patients may have been caused by primary respiratory sensitization.

Simultaneous estimation of liquid and solid gastric emptying using radiolabelled egg and water in supine normal subjects.

PubMed

Kris, M G; Yeh, S D; Gralla, R J; Young, C W

1986-01-01

To develop an additional method for the measurement of gastric emptying in supine subjects, 10 normal subjects were given a test meal containing 99Tc-labelled scrambled egg as the "solid" phase marker and 111In in tapwater as the marker for the "liquid" phase. The mean time for emptying 50% of the "solid" phase (t1/2) was 85 min and 29 min for the "liquid" phase. Three individuals were restudied with a mean difference between the two determinations of 10.8% for the "solid" phase and 6.5% for the "liquid" phase. Twenty-six additional studies attempted have been successfully completed in symptomatic patients with advanced cancer. This method provides a simple and reproducible procedure for the determination of gastric emptying that yields results similar to those reported for other test meals and can be used in debilitated patients.

Thermal shock resistance ceramic insulator

DOEpatents

Morgan, Chester S.; Johnson, William R.

1980-01-01

Thermal shock resistant cermet insulators containing 0.1-20 volume % metal present as a dispersed phase. The insulators are prepared by a process comprising the steps of (a) providing a first solid phase mixture of a ceramic powder and a metal precursor; (b) heating the first solid phase mixture above the minimum decomposition temperature of the metal precursor for no longer than 30 minutes and to a temperature sufficiently above the decomposition temperature to cause the selective decomposition of the metal precursor to the metal to provide a second solid phase mixture comprising particles of ceramic having discrete metal particles adhering to their surfaces, said metal particles having a mean diameter no more than 1/2 the mean diameter of the ceramic particles, and (c) densifying the second solid phase mixture to provide a cermet insulator having 0.1-20 volume % metal present as a dispersed phase.

Phase IV gross solids removal devices pilot study, 2004-2005.

DOT National Transportation Integrated Search

2005-12-01

The objective of the Phase IV Gross Solids Removal Device (GSRD) Pilot study was to evaluate : the performance of one non-proprietary device that can capture gross solids and that can be : incorporated into existing highway drainage systems or implem...

Characterization of the Solid-Phase Behavior of n-Nonylammonium Tetrachlorocuprate by Fourier Transform Infrared Spectroscopy

NASA Astrophysics Data System (ADS)

Ning, Guo

1995-06-01

The solid-phase behavior of [n-C9H19NH3]2CuCl4 was investigated by infrared spectroscopy. The nature of the three solid phases (phase I, phase II, and phase III) is discussed. A temperature-dependent study of infrared spectra provides evidence for the occurrence of structural phase transitions related to the dynamics of the alkyl chains and -NH3 polar heads. The phase transition at Tc1 (22°C) arises from variation in the interaction and packing structure of the chain. The phase transition at Tc2 (34°C) is related to variation in partial conformational order-disorder at the intramolecular level. The GTG or GTG‧ and small concentration of TG structures near the CH3 group are generated in phase III (above 38°C).

Role of Precursor-Conversion Chemistry in the Crystal-Phase Control of Catalytically Grown Colloidal Semiconductor Quantum Wires.

PubMed

Wang, Fudong; Buhro, William E

2017-12-26

Crystal-phase control is one of the most challenging problems in nanowire growth. We demonstrate that, in the solution-phase catalyzed growth of colloidal cadmium telluride (CdTe) quantum wires (QWs), the crystal phase can be controlled by manipulating the reaction chemistry of the Cd precursors and tri-n-octylphosphine telluride (TOPTe) to favor the production of either a CdTe solute or Te, which consequently determines the composition and (liquid or solid) state of the Bi x Cd y Te z catalyst nanoparticles. Growth of single-phase (e.g., wurtzite) QWs is achieved only from solid catalysts (y ≪ z) that enable the solution-solid-solid growth of the QWs, whereas the liquid catalysts (y ≈ z) fulfill the solution-liquid-solid growth of the polytypic QWs. Factors that affect the precursor-conversion chemistry are systematically accounted for, which are correlated with a kinetic study of the composition and state of the catalyst nanoparticles to understand the mechanism. This work reveals the role of the precursor-reaction chemistry in the crystal-phase control of catalytically grown colloidal QWs, opening the possibility of growing phase-pure QWs of other compositions.

Ultrasensitive Speciation Analysis of Mercury in Rice by Headspace Solid Phase Microextraction Using Porous Carbons and Gas Chromatography-Dielectric Barrier Discharge Optical Emission Spectrometry.

PubMed

Lin, Yao; Yang, Yuan; Li, Yuxuan; Yang, Lu; Hou, Xiandeng; Feng, Xinbin; Zheng, Chengbin

2016-03-01

Rice consumption is a primary pathway for human methylmercury (MeHg) exposure in inland mercury mining areas of Asia. In addition, the use of iodomethane, a common fumigant that significantly accelerates the methylation of mercury in soil under sunlight, could increase the MeHg exposure from rice. Conventional hyphenated techniques used for mercury speciation analysis are usually too costly for most developing countries. Consequently, there is an increased interest in the development of sensitive and inexpensive methods for the speciation of mercury in rice. In this work, gas chromatography (GC) coupled to dielectric barrier discharge optical emission spectrometry (DBD-OES) was developed for the speciation analysis of mercury in rice. Prior to GC-DBD-OES analysis, mercury species were derivatized to their volatile species with NaBPh4 and preconcentrated by headspace solid phase microextraction using porous carbons. Limits of detection of 0.5 μg kg(-1) (0.16 ng), 0.75 μg kg(-1) (0.24 ng), and 1.0 μg kg(-1) (0.34 ng) were obtained for Hg(2+), CH3Hg(+), and CH3CH2Hg(+), respectively, with relative standard deviations (RSDs) better than 5.2% and 6.8% for one fiber or fiber-to-fiber mode, respectively. Recoveries of 90-105% were obtained for the rice samples, demonstrating the applicability of the proposed technique. Owing to the small size, low power, and low gas consumption of DBD-OES as well as efficient extraction of mercury species by porous carbons headspace solid phase micro-extraction, the proposed technique provides several advantages including compactness, cost-effectiveness, and potential to couple with miniature GC to accomplish the field speciation of mercury in rice compared to conventional hyphenated techniques.

Atomistic simulation of solid-liquid coexistence for molecular systems: application to triazole and benzene.

PubMed

Eike, David M; Maginn, Edward J

2006-04-28

A method recently developed to rigorously determine solid-liquid equilibrium using a free-energy-based analysis has been extended to analyze multiatom molecular systems. This method is based on using a pseudosupercritical transformation path to reversibly transform between solid and liquid phases. Integration along this path yields the free energy difference at a single state point, which can then be used to determine the free energy difference as a function of temperature and therefore locate the coexistence temperature at a fixed pressure. The primary extension reported here is the introduction of an external potential field capable of inducing center of mass order along with secondary orientational order for molecules. The method is used to calculate the melting point of 1-H-1,2,4-triazole and benzene. Despite the fact that the triazole model gives accurate bulk densities for the liquid and crystal phases, it is found to do a poor job of reproducing the experimental crystal structure and heat of fusion. Consequently, it yields a melting point that is 100 K lower than the experimental value. On the other hand, the benzene model has been parametrized extensively to match a wide range of properties and yields a melting point that is only 20 K lower than the experimental value. Previous work in which a simple "direct heating" method was used actually found that the melting point of the benzene model was 50 K higher than the experimental value. This demonstrates the importance of using proper free energy methods to compute phase behavior. It also shows that the melting point is a very sensitive measure of force field quality that should be considered in parametrization efforts. The method described here provides a relatively simple approach for computing melting points of molecular systems.

Solid-phase microextraction with temperature-programmed desorption for the analysis of iodination disinfection byproducts.

PubMed

Frazey, P A; Barkley, R M; Sievers, R E

1998-02-01

An analytical approach for the determination of chlorination and iodination disinfection byproducts based on solid-phase microextraction (SPME) was developed. Solid-phase microextraction presents a simple, rapid, sensitive, and solvent-free approach to sample preparation in which analytes in either air or water matrixes are extracted into the polymeric coating of an optical fiber. Analytes are subsequently thermally desorbed in the injection port of a gas chromatograph for separation, detection, and quantitation. Thermal degradation of iodoform was observed during desorption from a polyacrylate fiber in initial GC/MS and GC/ECD experiments. Experiments were designed to determine SPME conditions that would allow quantification without significant degradation of analytes. Isothermal and temperature-programmed thermal desorptions were evaluated for efficacy in transferring analytes with wide-ranging volatilities and thermal stabilities into chromatographic analysis columns. A temperature-programmed desorption (TPD) (120-200 degrees C at 5 degrees C/min with an on-column injection port or 150-200 degrees C at 25 degrees C/min with a split/splitless injection port) was able to efficiently remove analytes with wide-ranging volatilities without causing thermal degradation. The SPME-TPD method was linear over 2-3 orders of magnitude with an electron capture detector and detection limits were in the submicrogram per liter range. Precision and detection limits for selected trihalomethanes were comparable to those of EPA method 551. Extraction efficiencies were not affected by the presence of 10 mg/L soap, 15 mg/L sodium iodide, and 6000 mg/L sodium thiosulfate. The SPME-TPD technique was applied to the determination of iodination disinfection byproducts from individual precursor compounds using GC/MS and to the quantitation of iodoform at trace levels in a water recycle system using GC/ECD.

Tandem solid-phase extraction followed by HPLC-ESI/QTOF/MS/MS for rapid screening and structural identification of trace diterpenoids in flowers of Rhododendron molle.

PubMed

Zou, Hong-Yan; Luo, Jun; Xu, De-Ran; Kong, Ling-Yi

2014-01-01

'Naoyanghua', composed of the flowers of Rhododendron molle G. Don, is a traditional Chinese medicine that is widely known for its toxicity. Grayanane-type diterpenoids are the main active ingredients in R. molle, as well as possibly their toxicity: they are, however, difficult to isolate and analyse using common chromatographic methods, due to their small amounts and absence of conjugated groups, such as phenyl and α, β-unsaturated ketone. To establish a highly sensitive, selective and reliable method for the qualitative evaluation of trace diterpenoids in the flowers of R. molle by using tandem solid-phase extraction followed by high-performance liquid chromatography with electrospray ionisation quadrupole-time-of-flight mass spectrometry (HPLC-ESI/QTOF/MS/MS). Tandem solid phase extraction (SPE) was undertaken using a polyamide cartridge and a C18E cartridge in succession to enrich the trace diterpenoids. HPLC-ESI/QTOF/MS/MS was used to determine the fragmentation patterns of diterpenoids and to tentatively characterise their fragmentation pathways. HPLC-ESI/QTOF/MS/MS detected a total of 14 diterpenoids, eight of which were identified by comparison with literature sources and six based on fragmentation analysis. Among the latter six, rhodojaponin VI-3-glucoside was tentatively identified as a new diterpenoid glycoside and rhodojaponin VII, rhodojaponin IV and rhodojaponin I were reported from R. molle for the first time. By qualitative research of diterpenoids in this plant by HPLC-ESI/QTOF/MS/MS, a reliable methodology for the analysis of these active constituents of R. molle was established for the first time. Copyright © 2014 John Wiley & Sons, Ltd.

Solid-liquid critical behavior of water in nanopores.

PubMed

Mochizuki, Kenji; Koga, Kenichiro

2015-07-07

Nanoconfined liquid water can transform into low-dimensional ices whose crystalline structures are dissimilar to any bulk ices and whose melting point may significantly rise with reducing the pore size, as revealed by computer simulation and confirmed by experiment. One of the intriguing, and as yet unresolved, questions concerns the observation that the liquid water may transform into a low-dimensional ice either via a first-order phase change or without any discontinuity in thermodynamic and dynamic properties, which suggests the existence of solid-liquid critical points in this class of nanoconfined systems. Here we explore the phase behavior of a model of water in carbon nanotubes in the temperature-pressure-diameter space by molecular dynamics simulation and provide unambiguous evidence to support solid-liquid critical phenomena of nanoconfined water. Solid-liquid first-order phase boundaries are determined by tracing spontaneous phase separation at various temperatures. All of the boundaries eventually cease to exist at the critical points and there appear loci of response function maxima, or the Widom lines, extending to the supercritical region. The finite-size scaling analysis of the density distribution supports the presence of both first-order and continuous phase changes between solid and liquid. At around the Widom line, there are microscopic domains of two phases, and continuous solid-liquid phase changes occur in such a way that the domains of one phase grow and those of the other evanesce as the thermodynamic state departs from the Widom line.

Simultaneous determination of flubendiamide its metabolite desiodo flubendiamide residues in cabbage, tomato and pigeon pea by HPLC.

PubMed

Paramasivam, M; Banerjee, Hemanta

2011-10-01

A sensitive and simple method for simultaneous analysis of flubendiamide and its metabolite desiodo flubendiamide in cabbage, tomato and pigeon pea has been developed. The residues were extracted with QuEChERS method followed by dispersive solid-phase extraction with primary secondary amine sorbent to remove co extractives, prior to analysis by HPLC coupled with UV-Vis detector. The recoveries of flubendiamide and desiodo flubendiamide were ranged from 85.1 to 98.5% and 85.9 to 97.1% respectively with relative standard deviations (RSD) less than 5% and sensitivity of 0.01 μg g(-1). The method offers a less expensive and safer alternative to the existing residue analysis methods for vegetables. © Springer Science+Business Media, LLC 2011

Sensitive Voltammetric Determination of Natural Flavonoid Quercetin on a Disposable Graphite Lead

PubMed Central

Vu, Dai Long; Žabčíková, Simona; Ertek, Bensu; Dilgin, Yusuf

2015-01-01

Summary In this paper, a pencil graphite electrode was pretreated using chronoamperometry technique in phosphate buffer solution (pH=7.0) for sensitive determination of quercetin. Oxidation of quercetin was investigated using pretreated pencil graphite electrode and anodic stripping differential pulse voltammetry. Under optimal conditions, the anodic current of quercetin exhibited linear response to its concentration in the range from 0.001 to 1.5 µmol/L with the limit of detection of 0.3·10–3 µmol/L. The proposed method was successfully applied for the determination of quercetin in cranberry and blackcurrant juices with recovery rate from 93.2 to 94.7%. Solid-phase extraction was found to be necessary prior to voltammetric determination of quercetin in fruit juice samples using pretreated pencil graphite electrode. PMID:27904372

Comparison of solid-phase and eluate assays to gauge the ecotoxicological risk of organic wastes on soil organisms.

PubMed

Domene, Xavier; Alcañiz, Josep M; Andrés, Pilar

2008-02-01

Development of methodologies to assess the safety of reusing polluted organic wastes in soil is a priority in Europe. In this study, and coupled with chemical analysis, seven organic wastes were subjected to different aquatic and soil bioassays. Tests were carried out with solid-phase waste and three different waste eluates (water, methanol, and dichloromethane). Solid-phase assays were indicated as the most suitable for waste testing not only in terms of relevance for real situations, but also because toxicity in eluates was generally not representative of the chronic effects in solid-phase. No general correlations were found between toxicity and waste pollutant burden, neither in solid-phase nor in eluate assays, showing the inability of chemical methods to predict the ecotoxicological risks of wastes. On the contrary, several physicochemical parameters reflecting the degree of low organic matter stability in wastes were the main contributors to the acute toxicity seen in collembolans and daphnids.

Molecular Simulation of the Free Energy for the Accurate Determination of Phase Transition Properties of Molecular Solids

NASA Astrophysics Data System (ADS)

Sellers, Michael; Lisal, Martin; Brennan, John

2015-06-01

Investigating the ability of a molecular model to accurately represent a real material is crucial to model development and use. When the model simulates materials in extreme conditions, one such property worth evaluating is the phase transition point. However, phase transitions are often overlooked or approximated because of difficulty or inaccuracy when simulating them. Techniques such as super-heating or super-squeezing a material to induce a phase change suffer from inherent timescale limitations leading to ``over-driving,'' and dual-phase simulations require many long-time runs to seek out what frequently results in an inexact location of phase-coexistence. We present a compilation of methods for the determination of solid-solid and solid-liquid phase transition points through the accurate calculation of the chemical potential. The methods are applied to the Smith-Bharadwaj atomistic potential's representation of cyclotrimethylene trinitramine (RDX) to accurately determine its melting point (Tm) and the alpha to gamma solid phase transition pressure. We also determine Tm for a coarse-grain model of RDX, and compare its value to experiment and atomistic counterpart. All methods are employed via the LAMMPS simulator, resulting in 60-70 simulations that total 30-50 ns. Approved for public release. Distribution is unlimited.

Analytical possibilities of different X-ray fluorescence systems for determination of trace elements in aqueous samples pre-concentrated with carbon nanotubes

NASA Astrophysics Data System (ADS)

Marguí, E.; Zawisza, B.; Skorek, R.; Theato, T.; Queralt, I.; Hidalgo, M.; Sitko, R.

2013-10-01

This study was aimed to achieve improved instrumental sensitivity and detection limits for multielement determination of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Se, Pb and Cd in liquid samples by using different X-ray fluorescence (XRF) configurations (a benchtop energy-dispersive X-ray fluorescence spectrometer, a benchtop polarised energy-dispersive X-ray fluorescence spectrometer and a wavelength-dispersive X-ray fluorescence spectrometer). The preconcentration of metals from liquid solutions consisted on a solid-phase extraction using carbon nanotubes (CNTs) as solid sorbents. After the extraction step, the aqueous sample was filtered and CNTs with the absorbed elements were collected onto a filter paper which was directly analyzed by XRF. The calculated detection limits in all cases were in the low ng mL- 1 range. Nevertheless, results obtained indicate the benefits, in terms of sensitivity, of using polarized X-ray sources using different secondary targets in comparison to conventional XRF systems, above all if Cd determination is required. The developed methodologies, using the aforementioned equipments, have been applied for multielement determination in water samples from an industrial area of Poland.

Polymer coating behavior of Rayleigh-SAW resonators with gold electrode structure for gas sensor applications.

PubMed

Avramov, Ivan D; Länge, Kerstin; Rupp, Swen; Rapp, Bastian; Rapp, Michael

2007-01-01

Results from systematic polymer coating experiments on surface acoustic wave (SAW) resonators and coupled resonator filters (CRF) on ST-cut quartz with a corrosion-proof electrode structure entirely made of gold (Au) are presented and compared with data from similar SAW devices using aluminium (Al) electrodes. The recently developed Au devices are intended to replace their earlier Al counterparts in sensor systems operating in highly reactive chemical gas environments. Solid parylene C and soft poly[chlorotrifluoroethylene-co-vinylidene fluoride] (PCFV) polymer films are deposited under identical conditions onto the surface of Al and Au devices. The electrical performance of the Parylene C coated devices is monitored online during film deposition. The PCVF coated devices are evaluated after film deposition. The experimental data show that the Au devices can stand up to 40% thicker solid films for the same amount of loss increase than the Al devices and retain better resonance and phase characteristics. The frequency sensitivities of Au and Al devices to parylene C deposition are nearly identical. After coating with soft PCFV sensing film, the Au devices provide up to two times higher gas sensitivity when probed with cooling agent, octane, or tetrachloroethylene.

Phase transition thermodynamics of bisphenols.

PubMed

Costa, José C S; Dávalos, Juan Z; Santos, Luís M N B F

2014-10-16

Herein we have studied, presented, and analyzed the phase equilibria thermodynamics of a bisphenols (BP-A, BP-E, BP-F, BP-AP, and BP-S) series. In particular, the heat capacities, melting temperatures, and vapor pressures at different temperatures as well as the standard enthalpies, entropies, and Gibbs energies of phase transition (fusion and sublimation) were experimentally determined. Also, we have presented the phase diagrams of each bisphenol derivative and investigated the key parameters related to the thermodynamic stability of the condensed phases. When all the bisphenol derivatives are compared at the same conditions, solids BP-AP and BP-S present lower volatilities (higher Gibbs energy of sublimation) and high melting temperatures due to the higher stability of their solid phases. Solids BP-A and BP-F present similar stabilities, whereas BP-E is more volatile. The introduction of -CH3 groups in BP-F (giving BP-E and BP-A) leads an entropic differentiation in the solid phase, whereas in the isotropic liquids the enthalpic and entropic differentiations are negligible.

Binary Solid-Liquid Phase Equilibria

ERIC Educational Resources Information Center

Ellison, Herbert R.

1978-01-01

Indicates some of the information that may be obtained from a binary solid-liquid phase equilibria experiment and a method to write a computer program that will plot an ideal phase diagram to which the experimental results may be compared. (Author/CP)

Purification of Derivatized Oligosaccharides by Solid Phase Extraction for Glycomic Analysis

PubMed Central

Zhang, Qiwei; Li, Henghui; Feng, Xiaojun; Liu, Bi-Feng; Liu, Xin

2014-01-01

Profiling of glycans released from proteins is very complex and important. To enhance the detection sensitivity, chemical derivatization is required for the analysis of carbohydrates. Due to the interference of excess reagents, a simple and reliable purification method is usually necessary for the derivatized oligosaccharides. Various SPE based methods have been applied for the clean-up process. To demonstrate the differences among these methods, seven types of self-packed SPE cartridges were systematically compared in this study. The optimized conditions were determined for each type of cartridge and it was found that microcrystalline cellulose was the most appropriate SPE material for the purification of derivatized oligosaccharide. Normal phase HPLC analysis of the derivatized maltoheptaose was realized with a detection limit of 0.12 pmol (S N−1 = 3) and a recovery over 70%. With the optimized SPE method, relative quantification analysis of N-glycans from model glycoproteins were carried out accurately and over 40 N-glycans from human serum samples were determined regardless of the isomers. Due to the high stability and sensitivity, microcrystalline cellulose cartridge showed potential applications in glycomics analysis. PMID:24705408

Role of lattice distortion on diffuse phase transition temperatures in Bi0.5Na0.5TiO3-BaTiO3 [BNBTO] solid solutions

NASA Astrophysics Data System (ADS)

Pradhan, Lagen Kumar; Pandey, Rabichandra; Kumar, Sunil; Supriya, Sweety; Kar, Manoranjan

2018-04-01

Effect of lattice distortion on diffuse phase transition in BNBTO solid solutions near Morphotropic phase boundary (MPB) has been investigated. Solid solutions of (Bi0.5Na0.5)1-xBaxTiO3 (with mole % of x= 0.04, 0.05, 0.06, 0.07 and 0.08) were prepared by the planetary ball mill method in ethanol medium. Rietveld refinement technique with rhombohedral (R3c) and tetragonal (P4bm) crystal symmetry has been employed for structural as well as phase analysis of the solid solutions. Both rhombohedral and tetragonal lattice distortion (c/a) tends toward the pseudo-cubic crystal symmetry with the increase of mole fraction of Ba2+ near MPB (x= 6 mole %). Also, the average crystallite size and grain size decrease with increase of mole fraction of Ba2+ in BNT ceramic are due to larger ionic radius of Ba2+ and grain boundary pinning process in the solid solutions respectively. Additionally, depolarization temperature (Td) and maximum temperature (Tm) reduces due to the lattice distortion of both the phases in BNBTO solid solutions, which is explained extensively. Significant increase of dielectric constant has been observed near MPB composition (x=6%) in BNBTO solid solutions.

Simultaneous analysis of gemfibrozil, morphine, and its two active metabolites in different mouse brain structures using solid-phase extraction with ultra-high performance liquid chromatography and tandem mass spectrometry with a deuterated internal standard.

PubMed

Yang, Zizhao; Wang, Lu; Xu, Mingcheng; Gu, Jingkai; Yu, Lushan; Zeng, Su

2016-06-01

A rapid and sensitive bioassay was established and validated to simultaneously determine gemfibrozil, morphine, morphine-3β-glucuronide, and morphine-6β-glucuronide in mouse cerebrum, epencephalon, and hippocampus based on ultra-high performance liquid chromatography and tandem mass spectrometry. The deuterated internal standard, M6G-d3, was mixed with the prepared samples at 10 ng/mL as the final concentration. The samples were transferred into the C18 solid-phase extraction columns with gradient elution for solid-phase extraction. The mobile phase consisted of methanol and 0.05% formic acid (pH 3.2). Multiple reaction monitoring has been applied to analyze gemfibrozil (m/z 249.0 → 121.0) in anion mode, and M6G-d3 (m/z 465.1 → 289.1), morphine (m/z 286.0 → 200.9), and M3G and M6G (m/z 462.1 → 286.1) in the positive ion mode. The method has a linear calibration range from 0.05 to 10 ng for gemfibrozil, morphine, and M3G and M6G with correlation coefficients >0.993. The lower limit of quantitation for all four analytes was 0.05 ng/mL, relative standard deviation of intra- and interday precision was less than 10.5%, and the relative error of accuracy was from -8.2 to 8.3% at low, medium, and high concentrations for all the analytes. In conclusion, gemfibrozil can influence the morphine antinociception after coronary heart disease induced chronic angina by the change in one of morphine metabolites', M3G, distribution in mouse brain. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of calcium on microbial reduction of solid phase uranium(VI).

PubMed

Liu, Chongxuan; Jeon, Byong-Hun; Zachara, John M; Wang, Zheming

2007-08-15

The effect of calcium on the dissolution and microbial reduction of a representative solid phase uranyl [U(VI)], sodium boltwoodite (NaUO(2)SiO(3)OH . 1.5H(2)O), was investigated to evaluate the rate-limiting step of microbial reduction of the solid phase U(VI). Microbial reduction experiments were performed in a culture of a dissimilatory metal-reducing bacterium (DMRB), Shewanella oneidensis strain MR-1, in a bicarbonate medium with lactate as electron donor at pH 6.8 buffered with PIPES. Calcium increased the rate of Na-boltwoodite dissolution and U(VI) bioavailability by increasing its solubility through the formation of a ternary aqueous calcium-uranyl-carbonate species. The ternary species, however, decreased the rates of microbial reduction of aqueous U(VI). Laser-induced fluorescence spectroscopy (LIFS) and transmission electron microscopy (TEM) collectively revealed that microbial reduction of solid phase U(VI) was a sequentially coupled process of Na-boltwoodite dissolution, U(VI) aqueous speciation, and microbial reduction of dissolved U(VI) to U(IV) that accumulated on bacterial surfaces/periplasm. Under studied experimental conditions, the overall rate of microbial reduction of solid phase U(VI) was limited by U(VI) dissolution reactions in solutions without calcium and limited by microbial reduction in solutions with calcium. Generally, the overall rate of microbial reduction of solid phase U(VI) was determined by the coupling of solid phase U(VI) dissolution, U(VI) aqueous speciation, and microbial reduction of dissolved U(VI) that were all affected by calcium. (c) 2007 Wiley Periodicals, Inc.

Multi-Component Profiling of Trace Volatiles in Blood by Gas Chromatography/Mass Spectrometry with Dynamic Headspace Extraction

PubMed Central

Kakuta, Shoji; Yamashita, Toshiyuki; Nishiumi, Shin; Yoshida, Masaru; Fukusaki, Eiichiro; Bamba, Takeshi

2015-01-01

A dynamic headspace extraction method (DHS) with high-pressure injection is described. This dynamic extraction method has superior sensitivity to solid phase micro extraction, SPME and is capable of extracting the entire gas phase by purging the headspace of a vial. Optimization of the DHS parameters resulted in a highly sensitive volatile profiling system with the ability to detect various volatile components including alcohols at nanogram levels. The average LOD for a standard volatile mixture was 0.50 ng mL−1, and the average LOD for alcohols was 0.66 ng mL−1. This method was used for the analysis of volatile components from biological samples and compared with acute and chronic inflammation models. The method permitted the identification of volatiles with the same profile pattern as in vitro oxidized lipid-derived volatiles. In addition, the concentration of alcohols and aldehydes from the acute inflammation model samples were significantly higher than that for the chronic inflammation model samples. The different profiles between these samples could also be identified by this method. Finally, it was possible to analyze alcohols and low-molecular-weight volatiles that are difficult to analyze by SPME in high sensitivity and to show volatile profiling based on multi-volatile simultaneous analysis. PMID:26819905

Multi-Component Profiling of Trace Volatiles in Blood by Gas Chromatography/Mass Spectrometry with Dynamic Headspace Extraction.

PubMed

Kakuta, Shoji; Yamashita, Toshiyuki; Nishiumi, Shin; Yoshida, Masaru; Fukusaki, Eiichiro; Bamba, Takeshi

2015-01-01

A dynamic headspace extraction method (DHS) with high-pressure injection is described. This dynamic extraction method has superior sensitivity to solid phase micro extraction, SPME and is capable of extracting the entire gas phase by purging the headspace of a vial. Optimization of the DHS parameters resulted in a highly sensitive volatile profiling system with the ability to detect various volatile components including alcohols at nanogram levels. The average LOD for a standard volatile mixture was 0.50 ng mL(-1), and the average LOD for alcohols was 0.66 ng mL(-1). This method was used for the analysis of volatile components from biological samples and compared with acute and chronic inflammation models. The method permitted the identification of volatiles with the same profile pattern as in vitro oxidized lipid-derived volatiles. In addition, the concentration of alcohols and aldehydes from the acute inflammation model samples were significantly higher than that for the chronic inflammation model samples. The different profiles between these samples could also be identified by this method. Finally, it was possible to analyze alcohols and low-molecular-weight volatiles that are difficult to analyze by SPME in high sensitivity and to show volatile profiling based on multi-volatile simultaneous analysis.

Determination of herbicides in mineral and stagnant waters at ng/L levels using capillary electrophoresis and UV detection combined with solid-phase extraction and sample stacking.

PubMed

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

2005-04-08

In this work, the combined use of solid-phase extraction (SPE) and on-line preconcentration strategies as normal stacking mode (NSM) and stacking with matrix removal (SWMR) for the ultrasensitive and simultaneous capillary electrophoresis-ultraviolet analysis (CE-UV) of five triazolopyrimidine sulfonanilide pesticides (i.e., diclosulam, cloransulam-methyl, flumetsulam, metosulam and florasulam) in different types of water is investigated. An adequate separation electrolyte for the separation and stacking of these pesticides was obtained, considering also its compatibility with MS detection, which consisted of 24 mM formic acid and 16 mM ammonium carbonate at pH 6.4. It was observed that the use of this running buffer together with the SWMR preconcentration method provided the best results in terms of sensitivity (between 6.54 and 11.9 microg/L) and peak efficiency (up to 550000 theoretical plates per meter, NTP/m). When this on-line preconcentration procedure was combined with an off-line sample preconcentration step as SPE using C18 cartridges, the selected herbicides could be detected in the ng/L range. The optimized SPE-SWMR-CE-UV method was applied to the determination of the selected group of pesticides in spiked and non-spiked mineral and stagnant waters. Recoveries ranged between 55 and 110% and limits of detection between 131 and 342 ng/L. This work shows the great possibilities of the combined use of SPE-SWMR-CE-UV to overcome the sensitivity problems usually linked to CE analysis.

A rapid and sensitive assay of perfluorocarboxylic acids in aqueous matrices by headspace solid phase microextraction-gas chromatography-triple quadrupole mass spectrometry.

PubMed

Monteleone, Marcello; Naccarato, Attilio; Sindona, Giovanni; Tagarelli, Antonio

2012-08-17

The work aims at developing a rapid and sensitive method for the quantification of perfluorocarboxylic acids in aqueous matrices. The proposed analytical approach is based on the use of solid phase microextraction in headspace mode after a fast derivatization of the carboxylate function by propylchloroformate/propanol mixture. Several fibers were evaluated and the optimization of the parameters affecting the SPME process was carried out using a central composite design. The optimum working conditions in terms of response values were achieved by performing analysis with CAR/PDMS fiber at room temperature, without addition of NaCl, with a sample volume of 6 ml and an extraction time of 10 min. Assay of PFCAs was performed by using a gas chromatography-triple quadrupole mass spectrometry (GC-QqQ MS) system in negative chemical ionization mode with ammonia as reagent gas. An overall evaluation of all analytical parameters shows that the proposed method provides satisfactory results. In particular, the observed accuracies, ranging from 84.4% to 116.8%, and the RSD values in the range 0.4% and 14.5% confirm the effectiveness of the developed protocol in the assay of PFCAs content in aqueous matrices. Moreover, LOD and LOQ values ranging from 0.08 to 6.6 ng l(-1) and from 0.17 to 14.3 ng l(-1), respectively, can be considered very satisfactory. None of the compounds were detected in six samples of river collected in Calabria. Copyright © 2012 Elsevier B.V. All rights reserved.

Determination of doping peptides via solid-phase microelution and accurate-mass quadrupole time-of-flight LC-MS.

PubMed

Cuervo, Darío; Loli, Cynthia; Fernández-Álvarez, María; Muñoz, Gloria; Carreras, Daniel

2017-10-15

A complete analytical protocol for the determination of 25 doping-related peptidic drugs and 3 metabolites in urine was developed by means of accurate-mass quadrupole time-of-flight (Q-TOF) LC-MS analysis following solid-phase extraction (SPE) on microplates and conventional SPE pre-treatment for initial testing and confirmation, respectively. These substances included growth hormone releasing factors, gonadotropin releasing factors and anti-diuretic hormones, with molecular weights ranging from 540 to 1320Da. Optimal experimental conditions were stablished after investigation of different parameters concerning sample preparation and instrumental analysis. Weak cation exchange SPE followed by C18 HPLC chromatography and accurate mass detection provided the required sensitivity and selectivity for all the target peptides under study. 2mg SPE on 96-well microplates can be used in combination with full scan MS detection for the initial testing, thus providing a fast, cost-effective and high-throughput protocol for the processing of a large batch of samples simultaneously. On the other hand, extraction on 30mg SPE cartridges and subsequent target MS/MS determination was the protocol of choice for confirmatory purposes. The methodology was validated in terms of selectivity, recovery, matrix effect, precision, sensitivity (limit of detection, LOD), cross contamination, carryover, robustness and stability. Recoveries ranged from 6 to 70% (microplates) and 17-95% (cartridges), with LODs from 0.1 to 1ng/mL. The suitability of the method was assessed by analyzing different spiked or excreted urines containing some of the target substances. Copyright © 2017 Elsevier B.V. All rights reserved.

Development of a sensitive and selective liquid chromatography-mass spectrometry method for high throughput analysis of paralytic shellfish toxins using graphitised carbon solid phase extraction.

PubMed

Boundy, Michael J; Selwood, Andrew I; Harwood, D Tim; McNabb, Paul S; Turner, Andrew D

2015-03-27

Routine regulatory monitoring of paralytic shellfish toxins (PST) commonly employs oxidative derivitisation and complex liquid chromatography fluorescence detection methods (LC-FL). The pre-column oxidation LC-FL method is currently implemented in New Zealand and the United Kingdom. When using this method positive samples are fractionated and two different oxidations are required to confirm the identity and quantity of each PST analogue present. There is a need for alternative methods that are simpler, provide faster turnaround times and have improved detection limits. Hydrophilic interaction liquid chromatography (HILIC) HPLC-MS/MS analysis of PST has been used for research purposes, but high detection limits and substantial sample matrix issues have prevented it from becoming a viable alternative for routine monitoring purposes. We have developed a HILIC UPLC-MS/MS method for paralytic shellfish toxins with an optimised desalting clean-up procedure on inexpensive carbon solid phase extraction cartridges for reduction of matrix interferences. This represents a major technical breakthrough and allows sensitive, selective and rapid analysis of paralytic shellfish toxins from a variety of sample types, including many commercially produced bivalve molluscan shellfish species. Additionally, this analytical approach avoids the need for complex calculations to determine sample toxicity, as unlike other methods each PST analogue is able to be quantified as a single resolved peak. This article presents the method development and optimisation information. A thorough single laboratory validation study has subsequently been performed and this data will be presented elsewhere. Copyright © 2015 Elsevier B.V. All rights reserved.

Combined solid-phase extraction and gas chromatography-mass spectrometry used for determination of chloropropanols in water.

PubMed

González, Paula; Racamonde, Inés; Carro, Antonia M; Lorenzo, Rosa A

2011-10-01

A sensitive and rapid derivatization method for the simultaneous determination of 1,3-dichloro-2-propanol (1,3-DCP) and 3-chloropropane-1,2-diol (3-MCPD) in water samples has been developed. The aim was to research the optimal conditions of the derivatization process for two selected reagents. A central composite design was used to determine the influence of derivatization time, derivatization temperature and reagent volume. A global desirability function was applied for multi-response optimization. The analysis was performed by gas chromatography-mass spectrometry. During the optimization of the extraction procedure, four different types of solid-phase extraction (SPE) columns were tested. It was demonstrated that the Oasis HLB cartridge produced the best recoveries of the target analytes. The pH value and the salinity were investigated using a Doehlert design. The best results for the SPE of both analytes were obtained with 1.5 g of NaCl and pH 6. The proposed method provides high sensitivity, good linearity (R(2)≥0.999) and repeatability (relative standard deviations % between 2.9 and 3.4%). Limits of detection and quantification were in the range of 1.4-11.2 ng/mL and 4.8-34.5 ng/mL, respectively. Recoveries obtained for water samples were ca. 100% for 1,3-DCP and 3-MCPD. The method has been successfully applied to the analysis of different samples including commercially bottled water, an influent and effluent sewage. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison of the solid-phase fragment condensation and phase-change approaches in the synthesis of salmon I calcitonin.

PubMed

Gatos, D; Tzavara, C

2001-02-01

Salmon I calcitonin was synthesized using both phase-change and conventional solid-phase fragment condensation (SPFC) approaches, utilizing the Rink amide linker (Fmoc-amido-2,4-dimethoxybenzyl-4-phenoxyacetic acid) combined with 2-chlorotrityl resin and the Fmoc/tBu(Trt)-based protection scheme. Phase-change synthesis, performed by the selective detachment of the fully protected C-terminal 22-mer peptide-linker from the resin and subsequent condensation in solution with the N-terminal 1-10 fragment, gave a product of slightly less purity (85 vs. 92%) than the corresponding synthesis on the solid-phase. In both cases salmon I calcitonin was easily obtained in high purity.

[Simultaneous determination of five synthetic sweeteners in food by solid phase extraction-high performance liquid chromatography-evaporative light scattering detection].

PubMed

Liu, Fang; Wang, Yan; Wang, Yuhong; Zhou, Junyi; Yan, Chao

2012-03-01

A high performance liquid chromatographic method with evaporative light scattering detection (HPLC-ELSD) was developed for the simultaneous determination of five synthetic sweeteners (acesulfame-K, saccharin sodium, sodium cyclamate, sucralose and aspartame) in food. The sweeteners were extracted by 0.1% (v/v) formic acid buffer solution. The extract of sample was cleaned up and concentrated with solid phase extraction (SPE) cartridge. Then the sweeteners were separated on a C18 column (3 microm) using 0.1% (v/v) formic acid buffer (adjusted to pH = 3.5 with aqueous ammonia solution)-methanol (61: 39, v/v) as mobile phase, and finally detected by ELSD. The results showed that the reasonable linearity was achieved for all the analytes over the range of 30 - 1000 mg/L with the correlation coefficients (r) greater than 0.997. The recoveries for the five sweeteners ranged from 85.6% to 109.0% at three spiked concentrations with the relative standard deviations (RSDs) lower than 4.0%. The limits of detection (LODs, S/N = 3) were 2.5 mg/L for both acesulfame-K and sucralose, 3 mg/L for saccharin sodium, 10 mg/L for sodium cyclamate, and 5 mg/L for aspartame. The method is simple, sensitive and low cost, and has been successfully applied to the simultaneous determination of the five synthetic sweeteners in food.

The Potential of Graphene as an Adsorbent for Five Pesticides from Different Classes in Rape Oil Samples Using Dispersive Solid-Phase Extraction.

PubMed

Madej, Katarzyna; Janiga, Katarzyna; Piekoszewski, Wojciech

2018-01-01

Isolation conditions for five pesticides (metazachlor, tebuconazole, λ -cyhalothrin, chlorpyrifos, and deltamethrin) from rape oil samples were examined using the dispersive solid-phase graphene extraction technique. To determine the optimal extraction conditions, a number of experimental factors (amount of graphene, amount of salt, type and volume of the desorbing solvent, desorption time with and without sonication energy, and temperature during desorption) were studied. The compounds of interest were separated and detected by an HPLC-UV employing a Kinetex XB-C18 column and a mobile phase consisting of acetonitrile and water flowing in a gradient mode. The optimized extraction conditions were: the amount of graphene 15 mg, desorbing solvent (acetonitrile) 5 mL, time desorption 10 min at 40°C, and amount of NaCl 1 g. The detection limit for metazachlor, tebuconazole, λ -cyhalothrin, and chlorpyrifos was 62.5 ng·g -1 , and for deltamethrin, it was 500 ng·g -1 . The obtained results lead to the conclusion that graphene may be successfully used for the isolation of the five pesticides from rape oil. However, their determination at low concentration levels, as they occur in real oil samples, requires the employment of appropriately highly sensitive analytical methods, as well as a more suitable graphene form (e.g., magnetically modified graphene).

Quantitation of promethazine and metabolites in urine samples using on-line solid-phase extraction and column-switching

NASA Technical Reports Server (NTRS)

Song, Q.; Putcha, L.; Harm, D. L. (Principal Investigator)

2001-01-01

A chromatographic method for the quantitation of promethazine (PMZ) and its three metabolites in urine employing on-line solid-phase extraction and column-switching has been developed. The column-switching system described here uses an extraction column for the purification of PMZ and its metabolites from a urine matrix. The extraneous matrix interference was removed by flushing the extraction column with a gradient elution. The analytes of interest were then eluted onto an analytical column for further chromatographic separation using a mobile phase of greater solvent strength. This method is specific and sensitive with a range of 3.75-1400 ng/ml for PMZ and 2.5-1400 ng/ml for the metabolites promethazine sulfoxide, monodesmethyl promethazine sulfoxide and monodesmethyl promethazine. The lower limits of quantitation (LLOQ) were 3.75 ng/ml with less than 6.2% C.V. for PMZ and 2.50 ng/ml with less than 11.5% C.V. for metabolites based on a signal-to-noise ratio of 10:1 or greater. The accuracy and precision were within +/- 11.8% in bias and not greater than 5.5% C.V. in intra- and inter-assay precision for PMZ and metabolites. Method robustness was investigated using a Plackett-Burman experimental design. The applicability of the analytical method for pharmacokinetic studies in humans is illustrated.

Navigating the Waters of Unconventional Crystalline Hydrates

PubMed Central

2015-01-01

Elucidating the crystal structures, transformations, and thermodynamics of the two zwitterionic hydrates (Hy2 and HyA) of 3-(4-dibenzo[b,f][1,4]oxepin-11-yl-piperazin-1-yl)-2,2-dimethylpropanoic acid (DB7) rationalizes the complex interplay of temperature, water activity, and pH on the solid form stability and transformation pathways to three neutral anhydrate polymorphs (Forms I, II°, and III). HyA contains 1.29 to 1.95 molecules of water per DB7 zwitterion (DB7z). Removal of the essential water stabilizing HyA causes it to collapse to an amorphous phase, frequently concomitantly nucleating the stable anhydrate Forms I and II°. Hy2 is a stoichiometric dihydrate and the only known precursor to Form III, a high energy disordered anhydrate, with the level of disorder depending on the drying conditions. X-ray crystallography, solid state NMR, and H/D exchange experiments on highly crystalline phase pure samples obtained by exquisite control over crystallization, filtration, and drying conditions, along with computational modeling, provided a molecular level understanding of this system. The slow rates of many transformations and sensitivity of equilibria to exact conditions, arising from its varying static and dynamic disorder and water mobility in different phases, meant that characterizing DB7 hydration in terms of simplified hydrate classifications was inappropriate for developing this pharmaceutical. PMID:26075319

Speciation of selenium in environmental samples by solid-phase spectrophotometry using 2,3-dichloro-6-(2,7-dihydroxy-naphthylazo)quinoxaline.

PubMed

Amin, Alaa S

2014-01-01

Solid-phase spectrophotometry was applied to determination of trace amounts of selenium (Se) in water, soil, plant materials, human hair, and a cosmetic preparation (lipstick). Se(IV) was sorbed in a dextran type lipophilic gel as a complex with 2,3-dichloro-6-(2,7-dihydroxy-naphthylazo)quinoxaline (DCDHNAQ), whereas Se(VI) was determined after boiling in HCI for 10 min to convert Se(VI) to Se(IV). Resin phase absorbances at 588 and 800 nm were measured directly, which allowed the determination of Se in the range of 0.2-3.3 microg/L with an RSD of 1.22%. The influences of analytical parameters including pH of the aqueous solution, amounts of DCDHNAQ, and sample volume were investigated. The molar absorptivities were found to be 1.09 x 10(6), 4.60 x 10(6), and 1.23 x 10(7) L/mol cm for 100, 500, and 1000 mL, respectively. The LOD and LOQ of the 500 mL sample method were 110 and 360 ng/L, respectively, when using 50 mg dextran type lipophilic gel. For a 1000 mL sample, the LOD and LOQ were 60 and 200 ng/L, respectively, using 50 mg of the exchanger. Increasing the sample volume enhanced the sensitivity. No considerable interferences were observed from other investigated anions and cations on the Se determination.

Separation and quantitation of three acidic herbicide residues in tobacco and soil by dispersive solid-phase extraction and UPLC-MS/MS.

PubMed

Xiong, Wei; Tao, Xiaoqiu; Pang, Su; Yang, Xue; Tang, GangLing; Bian, Zhaoyang

2014-01-01

A method for the determination of three acidic herbicides, dicamba, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in tobacco and soil has been developed based on the use of liquid-liquid extraction and dispersive solid-phase extraction (dispersive-SPE) followed by UPLC-MS/MS. Two percentage of (v/v) formic acid in acetonitrile as the extraction helped partitioning of analytes into the acetonitrile phase. The extract was then cleaned up by dispersive-SPE using primary secondary amine as selective sorbents. Quantitative analysis was done in the multiple-reaction monitoring mode using stable isotope-labeled internal standards for each compound. A separate internal standard for each analyte is required to minimize sample matrix effects on each analyte, which can lead to poor analyte recoveries and decreases in method accuracy and precision. The total analysis time was <4 min. The linear range of the method was from 1 to 100 ng mL(-1) with a limit of detection of each herbicide varied from 0.012 to 0.126 ng g(-1). The proposed method is faster, more sensitive and selective than the traditional methods and more accurate and robust than the published LC-MS/MS methods. © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Open-Label, Multicenter, Phase 1/2 Study of Tazemetostat (EZH2 Histone Methyl Transferase [HMT] Inhibitor) as a Single Agent in Subjects With Adv. Solid Tumors or With B-cell Lymphomas and Tazemetostat in Combination With Prednisolone in Subjects With DLBCL

ClinicalTrials.gov

2018-05-31

B-cell Lymphomas (Phase 1); Advanced Solid Tumors (Phase 1); Diffuse Large B-cell Lymphoma (Phase 2); Follicular Lymphoma (Phase 2); Transformed Follicular Lymphoma; Primary Mediastinal Large B-Cell Lymphoma

Simultaneous determination of 29 pharmaceuticals in fish muscle and plasma by ultrasonic extraction followed by SPE-UHPLC-MS/MS.

PubMed

Liu, You-Yu; Hu, Xia-Lin; Bao, Yi-Fan; Yin, Da-Qiang

2018-02-12

A confirmatory method for the simultaneous detection of 29 pharmaceuticals in fish muscle and plasma was developed by using solid-phase extraction combined with ultra high performance liquid chromatography and tandem mass spectrometry. Fish samples were extracted with methanol and enriched using Oasis HLB solid-phase extraction columns in one step. Twenty-nine target pharmaceuticals were quantified by the internal standard method and the calibration curves showed good linearity in a wide range with determination coefficients of greater than 0.913. The detection limits of the pharmaceuticals ranged from 0.01 to 2.00 μg/kg (μg/L). The applicability of the method was checked by precision and recovery experiments. The average recoveries of the 29 pharmaceuticals were between 61 and 111%, and all the relative standard deviations were below 25%. Our reported method has been demonstrated to be sensitive, convenient, rapid and reliable for the simultaneous determination of 29 pharmaceuticals in fish muscle and plasma. Real sample determination showed that 25 and 9 of the 29 compounds were detected in fish muscle and plasma, respectively. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Validated Method for the Quantification of Baclofen in Human Plasma Using Solid-Phase Extraction and Liquid Chromatography–Tandem Mass Spectrometry

PubMed Central

Nahar, Limon Khatun; Cordero, Rosa Elena; Nutt, David; Lingford-Hughes, Anne; Turton, Samuel; Durant, Claire; Wilson, Sue; Paterson, Sue

2016-01-01

Abstract A highly sensitive and fully validated method was developed for the quantification of baclofen in human plasma. After adjusting the pH of the plasma samples using a phosphate buffer solution (pH 4), baclofen was purified using mixed mode (C8/cation exchange) solid-phase extraction (SPE) cartridges. Endogenous water-soluble compounds and lipids were removed from the cartridges before the samples were eluted and concentrated. The samples were analyzed using triple-quadrupole liquid chromatography–tandem mass spectrometry (LC–MS-MS) with triggered dynamic multiple reaction monitoring mode for simultaneous quantification and confirmation. The assay was linear from 25 to 1,000 ng/mL (r2 > 0.999; n = 6). Intraday (n = 6) and interday (n = 15) imprecisions (% relative standard deviation) were <5%, and the average recovery was 30%. The limit of detection of the method was 5 ng/mL, and the limit of quantification was 25 ng/mL. Plasma samples from healthy male volunteers (n = 9, median age: 22) given two single oral doses of baclofen (10 and 60 mg) on nonconsecutive days were analyzed to demonstrate method applicability. PMID:26538544

Facile synthesis of poly(ionic liquid)-bonded magnetic nanospheres as a high-performance sorbent for the pretreatment and determination of phenolic compounds in water samples.

PubMed

Bi, Wentao; Wang, Man; Yang, Xiaodi; Row, Kyung Ho

2014-07-01

Poly(ionic liquid)-bonded magnetic nanospheres were easily synthesized and applied to the pretreatment and determination of phenolic compounds in water samples, which have detrimental effects on water quality and the health of living beings. The high affinity of poly(ionic liquid)s toward the target compounds as well as the magnetic behavior of Fe3 O4 were combined in this material to provide an efficient and simple magnetic solid-phase extraction approach. The adsorption behavior of the poly(ionic liquid)-bonded magnetic nanospheres was examined to optimize the synthesis. Different parameters affecting the magnetic solid-phase extraction of phenolic compounds were assessed in terms of adsorption and recovery. Under the optimal conditions, the proposed method showed excellent detection sensitivity with limits of detection in the range of 0.3-0.8 ng/mL and precision in the range of 1.2-3.3%. This method was also applied successfully to the analysis of real water samples; good spiked recoveries over the range of 82.5-99.2% were obtained. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optimization of a new method for extraction of cyanidin chloride and pelargonidin chloride anthocyanins with magnetic solid phase extraction and determination in fruit samples by HPLC with central composite design.

PubMed

Yari, Abdollah; Rashnoo, Saba

2017-11-01

Here, we are reporting a sensitive, simple and rapid method for the analysis of cyanidin chloride and pelargonidin chloride anthocyanins in cherry, sour cherry, pomegranate and barberry produced in Iran. The analytes were extracted with acetonitrile-hydrochloric acid (1% v/v) mixture under optimized pretreatment conditions. Clean-up of the extract from fruits was conducted by magnetic solid phase extraction using salicylic acid functionalized silica-coated magnetite nanoparticles (SCMNPs) as the adsorbent. The optimized conditions searched with central composite design. Working under optimum conditions specified as: SCMNPs modified with salicylic acid, sorbent contact time and sample 10min, mechanical stirring time 57.3min. HPLC with UV-detection was used for determination of the analytes. The limit of detection, LOD, obtained for the two anthocyanins were 0.02 and 0.03μgg -1 , respectively. The ranges of the spiked recoveries were 80.0-97.6 and 72.9-97.2%, with the relative standard deviations (RSD) of 2.1 and 2.5%, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of Bile Acids in Piglet Bile by Solid Phase Extraction and Liquid Chromatography-Electrospray Tandem Mass Spectrometry.

PubMed

Mi, Si; Lim, David W; Turner, Justine M; Wales, Paul W; Curtis, Jonathan M

2016-03-01

An LC/MS/MS-based method was developed for the determination of individual bile acids (BA) and their conjugates in porcine bile samples. The C18-based solid-phase extraction (SPE) procedure was optimized so that all 19 target BA and their glycine and taurine conjugates were collected with high recoveries for standards (89.1-100.2%). Following this, all 19 compounds were separated and quantified in a single 12 min chromatographic run. The method was validated in terms of linearity, sensitivity, accuracy, precision, and recovery. An LOD in the low ppb range with measured precisions in the range of 0.5-9.3% was achieved. The recoveries for all of the 19 analytes in bile samples were all >80%. The validated method was successfully applied to the profiling of BA and their conjugates in the bile from piglets treated with exogenous glucagon-like peptide-2 (GLP-2) in a preclinical model of neonatal parenteral nutrition-associated liver disease (PNALD). The method developed is rapid and could be easily implemented for routine analysis of BA and their conjugates in other biofluids or tissues.

Efficient and Stable Photovoltaic Characteristics of Quasi-Solid State DSSC using Polymer Gel Electrolyte Based on Ionic Liquid in Organosiloxane Polymer Gels

NASA Astrophysics Data System (ADS)

Pujiarti, H.; Arsyad, W. S.; Shobih; Muliani, L.; Hidayat, R.

2018-04-01

Dye-Sensitized Solar Cell (DSSC) is still one of the promising solar cell types among the third generation of solar cells because of easiness of fabrication and variety of available materials. In this type of solar cell, the electrolyte is one of the important components for regenerating excited dyes and transporting electric charge carriers to the counter electrode. Indeed, the power conversion efficiency of DSSC can be then significantly affected by the chemical and physical properties of the electrolyte. The simplest electrolyte system of an I-/I3 - redox couple in an organic solvent, however, has some drawbacks due to corrosive properties, volatile and leakage problem. Use of solid phase or gel phase electrolyte may overcome those problems, but it is often considered to suppress the efficiency due to low ion diffusion. Here, we report the photovoltaic characteristics of DSSC using polymer gel electrolyte (PGE), which is composed of ionic liquid and an organosiloxane polymer gel. The better cell performance with power conversion efficiency of about 6% has been obtained by optimizing the mesoporous size of the TiO2 layer and the PGE viscosity.

Molecularly imprinted solid-phase extraction for determination of tilmicosin in feed using high performance liquid chromatography.

PubMed

Zheng, Yaqiu; Liu, Yahong; Guo, Hongbin; He, Limin; Fang, Binghu; Zeng, Zhenling

2011-04-01

A simple, sensitive and reproducible molecularly imprinted solid-phase extraction (MISPE) coupled with high performance liquid chromatographic method was developed for monitoring tilmicosin in feeds. The polymers were prepared using tylosin as mimic template molecule, methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross-linking monomer, and chloroform as a solvent by bulk polymerization. Under the optimum MISPE conditions, the novel polymer sorbent can selectively extract and enrich tilmicosin from variety of feeds. The MISPE cartridge was better than non-imprinted, C(18) and HLB cartridges in terms of both recovery and precision. Mean recoveries of tilmicosin from five kinds of feeds spiked at 1, 10 and 50 mg kg(-1) ranged from 76.9% to 95.6%, with intra-day and inter-day relative standard deviation less than 7.6%. The linearity was ranged from 1.0 to 100 mg L(-1) for matrix standard solution (r=0.9990). The limit of detection was approximately 0.35 mg kg(-1) and the limit of quantification was approximately 0.98 mg kg(-1). There was cleaner chromatogram by using MISPE than C(18) and HLB SPE. Copyright © 2011 Elsevier B.V. All rights reserved.

Study on the temperature gradient evolution of large size nonlinear crystal based on the fluid-solid coupling theory

NASA Astrophysics Data System (ADS)

Sun, F. Z.; Zhang, P.; Liang, Y. C.; Lu, L. H.

2014-09-01

In the non-critical phase-matching (NCPM) along the Θ =90° direction, ADP and DKDP crystals which have many advantages, including a large effective nonlinear optical coefficient, a small PM angular sensitivity and non beam walk-off, at the non-critical phase-matching become the competitive candidates in the inertial confinement fusion(ICF) facility, so the reasonable temperature control of crystals has become more and more important .In this paper, the fluid-solid coupling models of ADP crystal and DKDP crystal which both have anisotropic thermal conductivity in the states of vacuum and non-vacuum were established firstly, and then simulated using the fluid analysis software Fluent. The results through the analysis show that the crystal surface temperature distribution is a ring shape, the temperature gradients in the direction of the optical axis both the crystals are 0.02°C and 0.01°C due to the air, the lowest temperature points of the crystals are both at the center of surface, and the temperatures are lower than 0.09°C and 0.05°C compared in the vacuum and non-vacuum environment, then propose two designs for heating apparatus.

Solid-phase micro-extraction procedure for the determination of 1,3-dichloro-2-propanol in water by on-fibre derivatisation with bis(trimethylsilyl)trifluoroacetamide.

PubMed

Carro, Antonia María; González, Paula; Fajar, Noelia; Lorenzo, Rosa Antonia; Cela, Rafael

2009-06-01

The headspace solid-phase micro-extraction technique with on-fibre derivatisation followed by gas chromatography-tandem mass spectrometry has been evaluated for the analysis of 1,3-dichloro-2-propanol in water. An asymmetric factorial design has been performed to study the influence of five experimental factors: extraction time and temperature, derivatisation time and temperature and pH. The best extraction performance is achieved in the headspace mode, with 5 mL stirred water samples (pH 4) containing 1.3 g of NaCl, equilibrated for 30 min at 25 degrees C, using divinylbenzene-carboxen-polydimethylsiloxane as the fibre coating. On-fibre derivatisation has been used for the first time with 50 microL of bis(trimethylsilyl)trifluoroacetamide at 25 degrees C during 15 min, leading to effective yields. The proposed method provides high sensitivity, good linearity and repeatability (relative standard deviation of 5.1% for 10 ng mL(-1) and n = 5). The limits of detection and quantification were 0.4 and 1.4 ng mL(-1), respectively. Analytical recoveries obtained for different water samples were approx. 100%.

An efficient method for the simultaneous determination of furan, 2-methylfuran and 2-pentylfuran in fruit juices by headspace solid phase microextraction and gas chromatography-flame ionisation detector.

PubMed

Hu, Gaofei; Zhu, Yan; Hernandez, Marta; Koutchma, Tatiana; Shao, Suqin

2016-02-01

A headspace solid phase microextraction (HS-SPME) procedure followed by gas chromatography-flame ionisation detector (GC-FID) analysis was developed and validated for the simultaneous analysis of furan, 2-methylfuran and 2-pentylfuran from juice samples. Extraction at 32 °C for 20 min with stirring at 600 rpm and NaCl concentration 15% (W/V) was the optimal HS-SPME condition for all the three compounds by using a carboxen/polydimethylsiloxane fused silica fibre (75 μm). The extracted compounds were base line separated on a SPB-1 GC column within 12 min. The relative standard deviations of all analytes were less than 6.7%. The recovery rates were between 90.2% and 110.1%. The limits of detection and limits of quantification were 0.056-0.23 ng/mL and 0.14-0.76 ng/mL, respectively. The results showed that the developed method was sensitive, precise, accurate and robust for the determination of furan, 2-methylfuran and 2-pentylfuran in complex matrices without interferences from other components. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

A method to detect diphenylamine contamination of apple fruit and storages using headspace solid phase micro-extraction and gas chromatography/mass spectroscopy.

PubMed

Song, Jun; Forney, Charles F; Jordan, Michael A

2014-10-01

Analysis of headspace concentrations of diphenylamine using solid phase micro-extraction (SPME) was examined for its suitability to detect DPA contamination and off-gassing in apple (Malus domestica) fruit, storage rooms and storage materials. Four SPME fibre coatings including polydimethylsiloxane (PDMS, 100 μm), PDMS/divinylbenzene (PDMS/DVB), Polyacrylate (PA) and PDMS 7 μm were evaluated. The average limits of detection and of quantification for head space DPA ranged from 0.13 to 0.72 μg L(-1) and 0.42 to 2.35 μg L(-1), respectively. Polyacrylate was identified to be the most suitable and compatible fibre for DPA analysis in apple samples, because of its high sensitivity to DPA and low fruit volatile interferences. SPME techniques were further applied to study contamination of DPA in apples, storage rooms and packaging materials. DPA was found in the air of storage rooms containing apples that were not treated with DPA. Wood and plastic bin material, bin liners, and foam insulation all adsorbed and off-gassed DPA and could be potential sources of contamination of untreated apples. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

Simultaneous determination of cyanogen chloride and cyanogen bromide in treated water at sub-microg/L levels by a new solid-phase microextraction-gas chromatographic-electron-capture detection method.

PubMed

Cancho, B; Ventur, F; Galceran, M

2000-11-03

A headspace solid-phase microextraction (HS-SPME) procedure has been developed and applied for the determination of cyanogen halides in treated water samples at microg/L concentrations. Several SPME coatings were tested, the divinylbenzene-Carboxen-polydimethylsiloxane fiber being the most appropriate coating. GC-electron-capture detection was used for separation and quantitation. Experimental parameters such as sample volume, addition of a salt, extraction time and desorption conditions were studied. The optimized method has an acceptable linearity, good precision, with RSD values <10% for both compounds, and it is sufficiently sensitive to detect ng/L levels. HS-SPME was compared with liquid-liquid microextraction (US Environmental Protection Agency Method 551.1) for the analysis of spiked ultrapure and granular activated carbon filtered water samples. There was good agreement between the results from both methods. Finally, the optimized procedure was applied to determine both compounds at the Barcelona water treatment plant (N.E. Spain). Cyanogen chloride in treated water was <1.0 microg/L and cyanogen bromide ranged from 3.2 to 6.4 microg/L.

Simultaneous Determination of Oleanolic Acid and Ursolic Acid by in Vivo Microdialysis via UHPLC-MS/MS Using Magnetic Dispersive Solid Phase Extraction Coupling with Microwave-Assisted Derivatization and Its Application to a Pharmacokinetic Study of Arctiumlappa L. Root Extract in Rats.

PubMed

Zheng, Zhenjia; Zhao, Xian-En; Zhu, Shuyun; Dang, Jun; Qiao, Xuguang; Qiu, Zhichang; Tao, Yanduo

2018-04-18

Simultaneous detection of oleanolic acid and ursolic acid in rat blood by in vivo microdialysis can provide important pharmacokinetics information. Microwave-assisted derivatization coupled with magnetic dispersive solid phase extraction was established for the determination of oleanolic acid and ursolic acid by liquid chromatography tandem mass spectrometry. 2'-Carbonyl-piperazine rhodamine B was first designed and synthesized as the derivatization reagent, which was easily adsorbed onto the surface of Fe 3 O 4 /graphene oxide. Simultaneous derivatization and extraction of oleanolic acid and ursolic acid were performed on Fe 3 O 4 /graphene oxide. The permanent positive charge of the derivatization reagent significantly improved the ionization efficiencies. The limits of detection were 0.025 and 0.020 ng/mL for oleanolic acid and ursolic acid, respectively. The validated method was shown to be promising for sensitive, accurate, and simultaneous determination of oleanolic acid and ursolic acid. It was used for their pharmacokinetics study in rat blood after oral administration of Arctiumlappa L. root extract.