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Sample records for liquid chromatographic fractions

  1. Synthesis, liquid chromatographic fractionation and partial characterization of polybrominated dibenzofuran congeners.

    PubMed

    Gallistl, Christoph; Vetter, Walter

    2016-04-15

    Polybrominated dibenzofurans (PBDFs) are a class of highly toxic environmental contaminants which comprises 135 structurally different congeners. While the gas chromatographic separation and analysis of the most polychlorinated dibenzofurans (PCDFs) are well-documented, comparably little data is currently available in the case of PBDFs. In this study dibenzofuran was brominated to give a mixture of ∼40 PBDFs with one to seven bromine atoms. This synthesis mixture was fractionated by both countercurrent chromatography (CCC) with the solvent system n-hexane/toluene/acetonitrile and non-aqueous reversed-phase high performance liquid chromatography (RP-HPLC) with acetonitrile as the mobile phase. All together 80 consecutive CCC fractions and 40 HPLC fractions were taken and analyzed for PBDFs by gas chromatography coupled to mass spectrometry (GC/MS). CCC and RP-HPLC offered orthogonal separation of the PBDF mixture. As a consequence, selected CCC fractions were further fractionated by RP-HPLC. In this way, eight PBDFs could be isolated and the structures of twelve PBDFs were elucidated by proton magnetic resonance spectroscopy ((1)H NMR). PMID:26993783

  2. High performance liquid chromatographic hydrocarbon group-type analyses of mid-distillates employing fuel-derived fractions as standards

    NASA Technical Reports Server (NTRS)

    Seng, G. T.; Otterson, D. A.

    1983-01-01

    Two high performance liquid chromatographic (HPLC) methods have been developed for the determination of saturates, olefins and aromatics in petroleum and shale derived mid-distillate fuels. In one method the fuel to be analyzed is reacted with sulfuric acid, to remove a substantial portion of the aromatics, which provides a reacted fuel fraction for use in group type quantitation. The second involves the removal of a substantial portion of the saturates fraction from the HPLC system to permit the determination of olefin concentrations as low as 0.3 volume percent, and to improve the accuracy and precision of olefins determinations. Each method was evaluated using model compound mixtures and real fuel samples.

  3. Liquid chromatographic extraction medium

    DOEpatents

    Horwitz, E.P.; Dietz, M.L.

    1994-09-13

    A method and apparatus are disclosed for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water. 1 fig.

  4. Liquid chromatographic extraction medium

    DOEpatents

    Horwitz, E. Philip; Dietz, Mark L.

    1994-01-01

    A method and apparatus for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column is described. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water.

  5. Analysis of anthocyanin pigments in Lonicera (Caerulea) extracts using chromatographic fractionation followed by microcolumn liquid chromatography-mass spectrometry.

    PubMed

    Myjavcová, Renáta; Marhol, Petr; Křen, Vladimír; Simánek, Vilím; Ulrichová, Jitka; Palíková, Irena; Papoušková, Barbora; Lemr, Karel; Bednář, Petr

    2010-12-17

    Anthocyanins from the fruit Lonicera caerulea L. var. kamtschatica (blueberry honeysuckle, Caprifoliaceae) were studied via (semi)preparative chromatographic fractionation followed by MS and μLC/MS analysis. The extraction procedure was optimized with respect to analytical purposes as well as its potential use for the preparation of nutraceuticals. The highest yield of anthocyanins was obtained using acidified methanol as the extraction medium. A comparable total anthocyanin content was obtained using a mixture of methanol and acetone. However, when Lonicera anthocyanins were in contact with acetone, a condensation reaction occurred to a large extent and related 5-methylpyranoanthocyanins were found. The effect of other extraction media, including ethanol as a "green" solvent, is also discussed. The potential of two fractionation procedures for extract purification differing in their chromatographic selectivity and scale was studied (i.e. using a Sephadex LH-20 gel column and a reversed phase). Fractions obtained by both procedures were used for a detailed analysis. MS and μLC/MS(2) methods were used for monitoring anthocyanin and 5-methylpyranoderivatives content as well as identifying less common and more complex dyes (dimer of cyanidin-3-hexoside, cyanidin-ethyl-catechin-hexosides, etc.). These more complex dyes are most likely formed during fruit treatment. PMID:21111888

  6. Dual liquid and gas chromatograph system

    DOEpatents

    Gay, Don D.

    1985-01-01

    A chromatographic system that utilizes one detection system for gas chromatographic and micro-liquid chromatographic determinations. The detection system is a direct-current, atmospheric-pressure, helium plasma emission spectrometer. The detector utilizes a non-transparent plasma source unit which contains the plasma region and two side-arms which receive effluents from the micro-liquid chromatograph and the gas chromatograph. The dual nature of this chromatographic system offers: (1) extreme flexibility in the samples to be examined; (2) extremely low sensitivity; (3) element selectivity; (4) long-term stability; (5) direct correlation of data from the liquid and gas samples; (6) simpler operation than with individual liquid and gas chromatographs, each with different detection systems; and (7) cheaper than a commercial liquid chromatograph and a gas chromatograph.

  7. Dual liquid and gas chromatograph system

    DOEpatents

    Gay, D.D.

    A chromatographic system is described that utilizes one detection system for gas chromatographic and micro-liquid chromatographic determinations. The detection system is a direct-current, atmospheric-pressure, helium plasma emission spectrometer. The detector utilizes a nontransparent plasma source unit which contains the plasma region and two side-arms which receive effluents from the micro-liquid chromatograph and the gas chromatograph. The dual nature of this chromatographic system offers: (1) extreme flexibility in the samples to be examined; (2) extreme low sensitivity; (3) element selectivity; (4) long-term stability; (5) direct correlation of data from the liquid and gas samples; (6) simpler operation than with individual liquid and gas chromatographs, each with different detection systems; and (7) cheaper than a commercial liquid chromatograph and a gas chromatograph.

  8. Liquid chromatographic enantioseparation of the brominated flame retardant 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE) and enantiomer fractions in seal blubber.

    PubMed

    Vetter, Walter; Recke, Roland von der; Ostrowicz, Patrizia; Rosenfelder, Natalie

    2010-01-01

    Enantioselective analyses of the chiral brominated flame retardant 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE) are the focus of this work. High performance liquid chromatography (HPLC) equipped with a column that had a chiral stationary phase consisting of a modified cellulose derivative allowed for the fractionation of the enantiomers of DPTE. The enantiomeric excess was 98.2% for enantiomer 1 and 99% for enantiomer 2. Polarimetric measurements verified that the first eluting enantiomer originated from (-)-DPTE and the second peak originated from (+)-DPTE. Two gas chromatographic columns allowed for the direct enantioresolution of DPTE. The elution order of DPTE enantiomers was the same as observed in the chiral HPLC system ((-)-DPTE before (+)-DPTE). The best enantioseparation was achieved on a Chirasil-DEX CB column, which was used to analyze the enantiomer fractions of DPTE in blubber and brain samples of hooded seals (Cystophora cristata) and harp seals (Phoca groenlandica) from the Barents and Greenland Seas. Analyses were carried out by means of gas chromatography/electron capture negative ion mass spectrometry operated in the selected ion monitoring (GC/ECNI-MS-SIM) mode. In both matrices, only minute deviations from the racemate were observed (maximum +/-3% excess of (-)-DPTE). However, the samples from the Barents Sea were either racemic or showed a slight excess of (+)-DPTE (up to 2.5%), whereas all samples from the Greenland Sea contained a slight excess (up to 4%) of (-)-DPTE. PMID:19863996

  9. AUTOMATED MEASUREMENTS OF INFRARED SPECTRA OF CHROMATOGRAPHICALLY SEPARATED FRACTIONS

    EPA Science Inventory

    The rapid identification of trace organic pollutants in water presents one of the more severe problems for environmental analytical chemists today. Spectroscopic identifications of chromatographically separated fractions, preferably without trapping each sample, yields more certa...

  10. Micro-column plasma emission liquid chromatograph

    DOEpatents

    Gay, Don D.

    1984-01-01

    In a direct current plasma emission spectrometer for use in combination with a micro-column liquid chromatograph, an improved plasma source unit. The plasma source unit includes a quartz capillary tube having an inlet means, outlet off gas means and a pair of spaced electrodes defining a plasma region in the tube. The inlet means is connected to and adapted to receive eluant of the liquid chromatograph along with a stream of plasma-forming gas. There is an opening through the wall of the capillary tube penetrating into the plasma region. A soft glass capillary light pipe is disposed at the opening, is connected to the spectrometer, and is adapted to transmit light passing from the plasma region to the spectrometer. There is also a source of electromotive force connected to the electrodes sufficient to initiate and sustain a plasma in the plasma region of the tube.

  11. High-pressure liquid chromatographic gradient mixer

    DOEpatents

    Daughton, C.G.; Sakaji, R.H.

    1982-09-08

    A gradient mixer effects the continuous mixing of any two miscible solvents without excessive decay or dispersion of the resultant isocratic effluent or of a linear or exponential gradient. The two solvents are fed under low or high pressure by means of two high performance liquid chromatographic pumps. The mixer comprises a series of ultra-low dead volume stainless steel tubes and low dead volume chambers. The two solvent streams impinge head-on at high fluxes. This initial nonhomogeneous mixture is then passed through a chamber packed with spirally-wound wires which cause turbulent mixing thereby homogenizing the mixture with minimum band-broadening.

  12. High pressure liquid chromatographic gradient mixer

    DOEpatents

    Daughton, Christian G.; Sakaji, Richard H.

    1985-01-01

    A gradient mixer which effects the continuous mixing of any two miscible solvents without excessive decay or dispersion of the resultant isocratic effluent or of a linear or exponential gradient. The two solvents are fed under low or high pressure by means of two high performance liquid chromatographic pumps. The mixer comprises a series of ultra-low dead volume stainless steel tubes and low dead volume chambers. The two solvent streams impinge head-on at high fluxes. This initial nonhomogeneous mixture is then passed through a chamber packed with spirally-wound wires which cause turbulent mixing thereby homogenizing the mixture with minimum "band-broadening".

  13. Interface for liquid chromatograph-mass spectrometer

    DOEpatents

    Andresen, Brian D.; Fought, Eric R.

    1989-01-01

    A moving belt interface for real-time, high-performance liquid chromatograph (HPLC)/mass spectrometer (MS) analysis which strips away the HPLC solvent as it emerges from the end of the HPLC column and leaves a residue suitable for mass-spectral analysis. The interface includes a portable, stand-alone apparatus having a plural stage vacuum station, a continuous ribbon or belt, a drive train magnetically coupled to an external drive motor, a calibrated HPLC delivery system, a heated probe tip and means located adjacent the probe tip for direct ionization of the residue on the belt. The interface is also capable of being readily adapted to fit any mass spectrometer.

  14. Interface for liquid chromatograph-mass spectrometer

    DOEpatents

    Andresen, B.D.; Fought, E.R.

    1989-09-19

    A moving belt interface is described for real-time, high-performance liquid chromatograph (HPLC)/mass spectrometer (MS) analysis which strips away the HPLC solvent as it emerges from the end of the HPLC column and leaves a residue suitable for mass-spectral analysis. The interface includes a portable, stand-alone apparatus having a plural stage vacuum station, a continuous ribbon or belt, a drive train magnetically coupled to an external drive motor, a calibrated HPLC delivery system, a heated probe tip and means located adjacent the probe tip for direct ionization of the residue on the belt. The interface is also capable of being readily adapted to fit any mass spectrometer. 8 figs.

  15. Chromatographic method for determining fouling tendency of liquid hydrocarbons

    SciTech Connect

    Dickakian, G.B.

    1988-06-21

    A method is described for determining the tendency of a liquid hydrocarbon stream to foul equipment comprising the steps of: (a) depositing a sample of liquid hydrocarbon from a liquid hydrocarbon stream onto a surface of a thin film in the presence of an asphaltene antisolvent, wherein the thin film is made up of a chromatographic separation material; (b) letting the sample of liquid hydrocarbon migrate radially outward within the film for sufficient time so that hydrocarbon compatible fractions in the sample separate from any hydrocarbon-incompatible asphaltenes in the sample, wherein the hydrocarbon compatible fractions form a matrix portion in the film and any hydrocarbon-incompatible asphaltenes form a dark ring within the matrix portion and wherein any ring formed is disposed within a central region of the matrix portion and is distinguished from the matrix portion by a dark area having a boundary with respect to a lighter area; and (c) determining the tendency of the liquid hydrocarbon stream to fuel equipment by comparing the matrix portion with any dark ring formed from any hydrocarbon-incompatible asphaltenes in the sample, wherein the area and intensity of any ring formed in relation to the matrix portion provides an indication of the tendency of the liquid hydrocarbon stream to foul equipment.

  16. NEW LIQUID CHROMATOGRAPHIC DETECTION SYSTEM FOR ENVIRONMENTAL POLLUTANTS

    EPA Science Inventory

    Resonance enhanced coherent anti-Stokes Raman spectrometry (CARS) has been demonstrated as a specific identification system for liquid chromatography for water pollution identification. To achieve this, liquid chromatographic preconcentration and separation and computer control o...

  17. Liquid chromatographic assay for dicloxacillin in plasma.

    PubMed

    Alderete, Oscar; González-Esquivel, Dinora F; Del Rivero, L Misael; Castro Torres, Nelly

    2004-06-15

    A simple high-performance liquid chromatographic method for the determination of dicloxacillin in plasma has been developed. The method only requires 0.5 ml of plasma, phosphate buffer solution (pH = 4.7), acidification with 0.5N hydrochloride acid and liquid extraction with dichloromethane. Posterior evaporation of organic under nitrogen steam and redissolution in mobile phase is carried out. The analysis was performed on a Spherisorb C18 (5 microm) column, using methanol -0.05 M phosphate buffer, pH = 4.7 (75:25; v/v) as mobile phase, with ultraviolet detection at 220 nm. Results showed that the assay is sensitive: 0.5 microg/ml. The response is linear in the range of 0.5 - 10 microg/ml. Maximum inter-day coefficient of variation was 12.4%. Mean extraction recovery obtained was 96.95%. Stability studies showed that the loss was not higher than 10%, samples are stable at room temperature for 6 h, at -20 Celsius for 2 months, processed samples were stable at least for 24 h and also after two freeze-thaw cycles. The method has been used to perform pharmacokinetic and bioequivalence studies in humans. PMID:15135112

  18. Liquid chromatographic determination of nicarbazin in feeds.

    PubMed

    Krabel, B J; Dickson, D A; Zimmermann, A G; Coleman, M R

    2000-01-01

    A new liquid chromatographic method has been developed for determination of nicarbazin in feeds. Approximately 40 g feed is extracted with 200 mL acetonitrile-water (80 + 20, v/v). An aliquot of the extract is filtered and assayed using a reversed-phase isocratic method that measures the 4,4'-dinitrocarbanilide moiety of nicarbazin at a wavelength of 340 nm. For medicated feeds, the method uses a standard linear range of 5 to 100 microg/mL. For lower levels, a linear range of 50 to 150 ng/mL can be used. The method has a limit of detection of 250 ng/g and a limit of quantitation of 500 ng/g in a 40 g feed sample. Recovery was 99.1%, with a range of 95.2 to 101.8%. In the typical U.S. dosing range of 27 to 113.5 g/ton, the precision of the method based on one analyst, one day, and 2 weighings ranged from 2.8% (113.5 g/ton) to 4.7% (27 g/ton). PMID:11048841

  19. Comparison of enzymatic and liquid chromatographic chloramphenicol assays

    SciTech Connect

    Weber, A.F.; Opheim, K.E.; Koup, J.R.; Smith, A.L.

    1981-02-01

    A radioenzymatic assay and a ''high-performance'' liquid chromatographic assay for chloramphenicol were compared by using 52 patient specimens, 24 mock unknowns, and 13 quality control samples. Both methods were found to be rapid, precise, accurate, and sensitive, and either would be suitable for monitoring chloramphenicol concentrations in small volumes of serum. Linear regression analysis of serum chloramphenicol concentrations in patients receiving chloramphenicol succinate yielded a regression equation of Y . 1.04X + 0.274 (X . high-performance liquid chromatographic assay; Y . radioenzymatic assay), with a correlation coefficient of 0.971.

  20. Gas-liquid chromatographic determination of morphine, heroin, and cocaine.

    PubMed

    Prager, M J; Harrington, S M; Governo, T F

    1979-03-01

    Morphine, heroin, and cocaine are quantitatively determined with the same gas-liquid chromatographic system. The compounds are separated on a 6 ft X 2 mm id glass column packed with a 1:1 mixture of 5% SE-30 on 80--100 mesh Chromosorb W and 3% OV-17 on 80--100 mesh Varaport 30. The column is temperature-programmed. Flame ionization detector responses are measured with a computer-based data system. Heroin and cocaine are chromatographed directly; morphine is derivatized first. The procedure was evaluated with previously analyzed commercial and forensic samples. Accuracy and precision were 5 and 3%, respectively. PMID:447602

  1. Combined liquid chromatograph/mass spectrometer for involatile biological samples.

    PubMed

    Blakley, C R; Carmody, J C; Vestal, M L

    1980-09-01

    A new liquid chromatograph/mass spectrometer has been developed in our laboratory for application to analysis of biological molecules of extremely low volatility. Oxyhydrogen flames rapidly vaporize the total liquid-chromatographic effluent, and molecular and particle beam techniques are used to efficiently transfer the sample to the ionization source of the mass spectrometer. This new instrument is comparable in cost and complexity to a combined gas chromatograph/mass spectrometer, but extends the capabilities of combined chromatography/mass spectrometry to a broad range of compounds not previously accessible. We are currently testing biologically significant samples with this instrument, using reversed-phase liquid-chromatographic separation and both positive and negative ion chemical-ionization mass spectrometry. Results have been obtained from mixtures of nucleic acid components--bases, nucleosides, and nucleotides--and from amino acids, peptides, saccharides, fatty acids, vitamins, and antibiotics. In all cases investigated to date, ions indicative of molecular mass are obtained in at least one of the operating modes available. Detection limits are typically in the 1-10 ng range for full mass scans (about 80-600 amu); sub-nanogram quantities are usually detectable with single-ion monitoring. PMID:7408175

  2. Liquid chromatographic analysis of coal surface properties

    SciTech Connect

    Kwon, K.C.

    1992-04-07

    The main objectives of this proposed research work are to refine further the inverse liquid chromatography technique for the study of surface properties of raw coals, treated coals and coal minerals in water, to evaluate relatively surface properties of raw coals, treated coals and coal minerals by inverse liquid chromatography, and to evaluate flotability of various treated coals in conjunction with surface properties of coals. Coals such as Pittsburgh seam coal, Illinois No. 6 coal, Wyodak coal are chosen as representatives of high-rank bituminous coal, high volatile bituminous coal and subbituminous coal, respectively. Coal minerals such as pyrite and dolomite are chosen as representative coal minerals.

  3. [Chromatographic analysis of low molecular weight fraction of cerebrospinal fluid in children with acute neuroinfections].

    PubMed

    Alekseeva, L A; Shatik, S V; Sorokina, M N; Karasev, V V

    2002-05-01

    Low molecular-weight (oligopeptide) fraction of the cerebrospinal fluid was analyzed by high-performance reversed phase liquid chromatography in 30 children with bacterial and viral neuroinfections. The incidence and height of chromathoraphic peaks in bacterial meningitis depended on the disease etiology, stage, and severity. Qualitative and quantitative composition of low molecular-weight fraction of the liquor varied in patients with viral neuroinfections, depending on the severity of the cerebral parenchyma involvement. Differences in chromatographic profiles in complicated and uneventful course of neuroinfections indicate a possible damaging, protective, or regulatory effect of the liquor peptides. These data focus the attention on the role of oligopeptides in the genesis of neuroinfectious process, significance of search for peptide markers, their further isolation, identification, and development of test systems available for clinical application. PMID:12085699

  4. Liquid chromatographic determination of benzo(a)pyrene in total particulate matter of cigarette smoke

    SciTech Connect

    Tomkins, B.A.; Jenkins, R.A.; Griest, W.H.; Reagan, R.R.; Holladay, S.K.

    1985-09-01

    The benzo(a)pyrene (BaP) delivery of reference and commercially available tobacco cigarettes, as well as reference and placebo marijuana cigarettes, is determined using a sequential liquid chromatographic/liquid chromatographic procedure. The total particulate matter of sample cigarette smoke is collected using a Cambridge filter pad, which is ultrasonically extracted with acetone. The resulting extract is filtered, then fractionated using semipreparative-scale normal phase liquid chromatography (LC). Quantitative determination is achieved using analytical-scale reverse phase LC equipped with a fluorescence detector. The method is precise (+/- 10-15% relative standard deviation) and yields 85% or better BaP recovery at the ng/cig. level. A single pad may be analyzed in 8 person-hours, while a more typical lot of 12 pads (6 pads each for 2 cigarette brands) may be analyzed in 10 person-days.

  5. [Development of online conventional array-based two-dimensional liquid chromatographic system for proteins separation in human plasma].

    PubMed

    Huang, Zhi; Hong, Guangfeng; Gao, Mingxia; Zhang, Xiangmin

    2014-04-01

    Human plasma is one of the proteins-containing samples most difficult to characterize on account of the wide dynamic concentration range of its intact proteins. Herein, we developed a high-throughput conventional array-based two-dimensional liquid chromatographic system for proteins separation in human plasma in online mode. In the system, a conventional strong-anion exchange chromatographic column was used as the first separation dimension and eight parallel conventional reversed-phase liquid chromatographic columns were integrated as the second separation dimension. The fractions from the first dimension were sequentially transferred into the corresponding reversed-phase liquid chromatographic precolumns for retention and enrichment using a 10-port electrically actuated multi-position valve. The second dimensional solvent flow was directly and identically split into 8 channels. The fractions were concurrently back-flushed from the precolumns into the 8 conventional RP columns and were separated simultaneously. An 8-channel fraction collector was refitted to collect the reversed-phase liquid chromatographic fractions for further investigation. Bicinchoninic acid (BCA) dyein solution was conveniently used for high-abundance protein location. Two separation dimensions were relatively independent parts, as well as each channel of the second dimensional array separation. Therefore, the new system could improve the separation throughput and total peak capacity. The system was successfully applied for the separation of human plasma intact proteins. The results indicated the established system is an effective method for removing high abundance proteins in plasma and in-depth research in plasma proteomics. PMID:25069321

  6. Hand-portable liquid chromatographic instrumentation.

    PubMed

    Sharma, Sonika; Tolley, Luke T; Tolley, H Dennis; Plistil, Alex; Stearns, Stanley D; Lee, Milton L

    2015-11-20

    Over the last four decades, liquid chromatography (LC) has experienced an evolution to smaller columns and particles, new stationary phases and low flow rate instrumentation. However, the development of person-portable LC has not followed, mainly due to difficulties encountered in miniaturizing pumps and detectors, and in reducing solvent consumption. The recent introduction of small, non-splitting pumping systems and UV-absorption detectors for use with capillary columns has finally provided miniaturized instrumentation suitable for high-performance hand-portable LC. Fully integrated microfabricated LC still remains a significant challenge. Ion chromatography (IC) has been successfully miniaturized and applied for field analysis; however, applications are mostly limited to inorganic and small organic ions. This review covers advancements that make possible more rapid expansion of portable forms of LC and IC. PMID:26592464

  7. Micro-column plasma emission liquid chromatograph. [Patent application

    DOEpatents

    Gay, D.D.

    1982-08-12

    In a direct current plasma emission spectrometer for use in combination with a microcolumn liquid chromatograph, an improved plasma source unit is claimed. The plasma source unit includes a quartz capillary tube having an inlet means, outlet off gas means and a pair of spaced electrodes defining a plasma region in the tube. The inlet means is connected to and adapted to receive eluant of the liquid chromatograph along with a stream of plasma-forming gas. There is an opening through the wall of the capillary tube penetrating into the plasma region. A soft glass capillary light pipe is disposed at the opening, is connected to the spectrometer, and is adapted to transmit light passing from the plasma region to the spectrometer. There is also a source of electromotive force connected to the electrodes sufficient to initiate and sustain a plasma in the plasma region of the tube.

  8. Basicity of aromatic amines from liquid chromatographic behavior

    NASA Technical Reports Server (NTRS)

    Young, P. R.; Mcnair, H. M.

    1975-01-01

    A liquid chromatographic investigation was conducted to determine whether the adsorption of weakly basic aromatic amines on slightly acidic silica gel adsorbents could be used to study their relative basicity. Under proper conditions, a linear correlation between pKb and log of capacity factor was observed. This finding may prove useful in helping to predict the relative basicity of closely related aromatic diamines, especially new amines being synthesized for polymer synthesis.

  9. Fractionalized gapless quantum vortex liquids

    NASA Astrophysics Data System (ADS)

    Wang, Chong; Senthil, T.

    2015-05-01

    The standard theoretical approach to gapless spin liquid phases of two-dimensional frustrated quantum antiferromagnets invokes the concept of fermionic slave particles into which the spin fractionalizes. As an alternate we explore different kinds of gapless spin liquid phases in frustrated quantum magnets with X Y anisotropy where the vortex of the spin fractionalizes into gapless itinerant fermions. The resulting gapless fractionalized vortex liquid phases are studied within a slave particle framework that is dual to the usual one. We demonstrate the stability of some such phases and describe their properties. We give an explicit construction in an X Y -spin-1 system on triangular lattice, and interpret it as a critical phase in the vicinity of spin-nematic states.

  10. High-performance liquid chromatographic analysis of ampicillin.

    PubMed

    Tsuji, K; Robertson, J H

    1975-09-01

    A high-pressure liquid chromatographic method for the analysis of ampicillin is described. The method uses a 1-m long stainless steel column packed with anionic exchange resin, with a mobile phase of 0.02 M NaNO3 in 0.01 M pH 9.15 borate buffer at a flow rate of 0.45 ml/min. The degradation products of ampicillin, penicillenic and penicilloic acids of ampicillin, can be separated and quantitated in less than 12 min of chromatographic time. The relative standard deviation for the analysis of ampicillin is less than 1%, and the method is sensitive to approximately 20 ng of ampicillin/sample injected. The method was applied to the analysis of various pharmaceutical preparations of ampicillin. It is also applicable, with a slight modification, for the analysis of penicillins G and V. PMID:1185575

  11. Liquid chromatographic determination of carbadox residues in animal feed.

    PubMed

    Roybal, J E; Munns, R K; Shimoda, W

    1985-01-01

    A liquid chromatographic (LC) method for determining residues of carbadox in the 0.01-10 ppm range in swine feed is described. Carbadox is extracted from ground feed with 25% acidified methanol-CHCl3, removed from emulsion-forming coextractables via an alumina column, separated from highly colored pigments by acid-base liquid-liquid partitioning, and finally isolated from interferences on a second alumina column. Isocratic reverse phase LC at 305 nm is used for quantitation. The average overall recovery at the 0.1, 0.5, and 1.0 ppm spike levels was 83.0% with a standard deviation of 2.04% and a coefficient of variation of 2.46%. PMID:4030635

  12. Liquid chromatographic determination of clobetasone-17-butyrate in ointments.

    PubMed

    Patel, A G; Patel, R B; Patel, M R

    1990-01-01

    A liquid chromatographic (LC) method has been developed for determination of clobetasone-17-butyrate in ointment using clobetasone propionate as an internal standard. Separation was carried out on a C18 reverse-phase column using water-methanol as a mobile phase. Methylparaben and propylparaben (both sodium salt) used as preservatives did not interfere with separation. Compounds are detected photometrically at 235 nm. Mean assay results for 0.05% commercial ointments were 100.36% (n = 5). Mean recovery of clobetasone-17-butyrate added to commercial ointment was 99.89%. PMID:2289922

  13. Liquid chromatographic determination and liquid chromatographic-thermospray mass spectrometric confirmation of nicarbazin in chicken tissues: interlaboratory study.

    PubMed

    Leadbetter, M G; Matusik, J E

    1993-01-01

    The U.S. Food and Drug Administration sponsored an interlaboratory study of a liquid chromatographic determination with ultraviolet detection of nicarbazin in chicken liver and muscle tissues. The method determined the 4,4'-dinitrocarbanilide (DNC) portion of nicarbazin. The interlaboratory study of the determinative method was successful for nicarbazin at the 4 ppm level. Results showed good reproducibility for the fortified liver and muscle samples. Mean interlaboratory recoveries and percent coefficients of variation at about 4 ppm were 87.1 and 10.9%, respectively, for muscle and 87.4 and 7.5%, respectively, for liver. The interlaboratory analyses of the dosed liver and muscle tissues produced concentration levels similar to those obtained by the sponsor. The confirmatory procedure, which identified DNC in purified tissue extracts, used liquid chromatography-thermospray/mass spectrometry. The confirmatory procedure was successfully evaluated by one FDA laboratory. PMID:8471868

  14. Chromatographic fractionation of fullerenes containing noble gas atoms

    NASA Astrophysics Data System (ADS)

    Saunders, M.; Khong, A.; Shimshi, R.; Jiménez-Vázquez, H. A.; Cross, R. J.

    1996-01-01

    Buckminsterfullerence containing krypton atoms inside the cage was partially separated from empty fullerene via column chromatography. The krypton content of portions of the peak emerging from the column was determined by the pyrolytic release of the krypton followed by mass spectrometry. It was found that material emerging more slowly is about 30% enriched over a faster fraction.

  15. Liquid Chromatographic Determination of Amnesic Shellfish Poison in Mussels

    NASA Astrophysics Data System (ADS)

    Duxbury, Mark

    2000-10-01

    A simple, rapid, high-performance liquid chromatographic experiment suitable for undergraduate students is described for determining amnesic shellfish poison in mussels. The poison itself is an unusual naturally occurring amino acid, domoic acid, that has been found in seafood, particularly shellfish, worldwide. The symptoms of poisoning include amnesia (memory loss), loss of balance, mental confusion, nausea, vomiting, diarrhea, coma, and in extreme cases death. The domoic acid is extracted from homogenized mussel tissue by boiling in water for 5 minutes. The homogenate is cooled and centrifuged, and an aliquot of the supernatant is diluted and analyzed by isocratic HPLC using a C18 column and an acetonitrile-water mobile phase at pH 2.5 with UV detection at 242 nm.

  16. Liquid chromatographic determination of tetracycline residues in animal feeds.

    PubMed

    Martinez, E E; Shimoda, W

    1988-01-01

    A liquid chromatographic method for the multiresidue determination of tetracyclines (TCs) in feeds is described. The levels of quantitation were 10 ppm each for tetracycline-HCl (TC), oxytetracycline (OTC), and chlortetracycline-HCl (CTC); the detection limit was 40 ppb for each. The calibration curves were linear between 2.5 and 100 ppm. The procedure involved double extraction with pH 2.0 and pH 4.5 McIlvain buffers, cleanup on a Sephadex LH-20 column, separation on a Nova-Pak C18 column, and detection at 370 nm. Recoveries of 10 micrograms/g of each TC in multiresidue feed samples ranged from 55.8 to 75.5% for OTC, 71.6 to 100% for TC, and 22.4 to 60.6% for CTC. The identities of the TCs were confirmed by thin layer chromatography. PMID:3391942

  17. Comprehensive two-dimensional liquid chromatographic analysis of poloxamers.

    PubMed

    Malik, Muhammad Imran; Lee, Sanghoon; Chang, Taihyun

    2016-04-15

    Poloxamers are low molar mass triblock copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), having number of applications as non-ionic surfactants. Comprehensive one and two-dimensional liquid chromatographic (LC) analysis of these materials is proposed in this study. The separation of oligomers of both types (PEO and PPO) is demonstrated for several commercial poloxamers. This is accomplished at the critical conditions for one of the block while interaction for the other block. Reversed phase LC at CAP of PEO allowed for oligomeric separation of triblock copolymers with regard to PPO block whereas normal phase LC at CAP of PPO renders oligomeric separation with respect to PEO block. The oligomeric separation with regard to PEO and PPO are coupled online (comprehensive 2D-LC) to reveal two-dimensional contour plots by unconventional 2D IC×IC (interaction chromatography) coupling. The study provides chemical composition mapping of both PEO and PPO, equivalent to combined molar mass and chemical composition mapping for several commercial poloxamers. PMID:26994923

  18. Liquid-chromatographic determination of sarafloxacin residues in channel catfish muscle-tissue

    USGS Publications Warehouse

    Meinertz, J.R.; Dawson, V.K.; Gingerich, W.H.; Cheng, B.; Tubergen, M.M.

    1994-01-01

    A liquid chromatographic method is described for the determination of sarafloxacin hydrochloride residues i n channel catfish (ictalurus punctatus) fillets. Sarafloxacin was extracted from fillet tissue with acetonitrile=water (1 + 1). The extract was centrifuged and the supernatant was partitioned with hexane. The aqueous fraction was filtered through a 0.45 Mum filter and evaporated to dryness. The sample was redissolved with 20% acetonitrile-methanol (3 + 2) and 80% trifluoroacetic acid (0.1%), Centrifuged, and filtered to remove proteins. Samples were analyzed by chromatography with gradient elution on a c18 column and with fluorescence detection (excitation at 280 nm and emission above 389 nm). Mean recoveries ranged from 85.4 To 104%, and relative standard deviations ranged from 1.06 To 5.58% In samples spiked at concentrations of 10.0-863.8 Ng/g. The method detection limit for sarafloxacin was 1.4 Ng/g.

  19. Method for liquid chromatographic extraction of strontium from acid solutions

    DOEpatents

    Horwitz, E. Philip; Dietz, Mark L.

    1992-01-01

    A method and apparatus for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column is described. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water.

  20. Cefaclor pharmacokinetic parameters: serum concentrations determined by a new high-performance liquid chromatographic technique.

    PubMed

    Rotschafer, J C; Crossley, K B; Lesar, T S; Zaske, D; Miller, K

    1982-01-01

    Pharmacokinetic parameters of cefaclor were studied in eight patients after an oral dose of 250 mg. Serum samples were obtained before and on 19 occasions after oral administration. Cefaclor serum concentrations were determined by a new high-performance liquid chromatographic technique. PMID:7081972

  1. High Performance Liquid Chromatographic Analysis of Phytoplankton Pigments Using a C16-Amide Column

    EPA Science Inventory

    A reverse-phase high performance liquid chromatographic (RP-HPLC) method was developed to analyze in a single run, most polar and non-polar chlorophylls and carotenoids from marine phytoplankton. The method is based on a RP-C16-Amide column and a ternary gradient system consistin...

  2. Three radioactivity detectors for liquid-chromatographic systems compared

    SciTech Connect

    Frey, B.M.; Frey, F.J.

    1982-04-01

    Three radioactivity detectors coupled to a ''high-performance'' liquid-chromatography system are compared with regard to static efficiency, dynamic efficiency, background measurements, and within- and between-day variabilities. Their advantages and disadvantages are discussed.

  3. Process for stabilization of coal liquid fractions

    DOEpatents

    Davies, Geoffrey; El-Toukhy, Ahmed

    1987-01-01

    Coal liquid fractions to be used as fuels are stabilized against gum formation and viscosity increases during storage, permitting the fuel to be burned as is, without further expensive treatments to remove gums or gum-forming materials. Stabilization is accomplished by addition of cyclohexanol or other simple inexpensive secondary and tertiary alcohols, secondary and tertiary amines, and ketones to such coal liquids at levels of 5-25% by weight with respect to the coal liquid being treated. Cyclohexanol is a particularly effective and cost-efficient stabilizer. Other stabilizers are isopropanol, diphenylmethanol, tertiary butanol, dipropylamine, triethylamine, diphenylamine, ethylmethylketone, cyclohexanone, methylphenylketone, and benzophenone. Experimental data indicate that stabilization is achieved by breaking hydrogen bonds between phenols in the coal liquid, thereby preventing or retarding oxidative coupling. In addition, it has been found that coal liquid fractions stabilized according to the invention can be mixed with petroleum-derived liquid fuels to produce mixtures in which gum deposition is prevented or reduced relative to similar mixtures not containing stabilizer.

  4. A rapid and sensitive high performance liquid chromatographic analysis of clofazimine in plasma.

    PubMed

    Krishnan, T R; Abraham, I

    1992-12-01

    The high performance liquid chromatographic (HPLC) method of Gidoh, et al. has been modified substantially to provide a simple, rapid, and relatively inexpensive procedure for measuring clofazimine in plasma. The modification involves the use of commonly available laboratory reagents instead of custom-made ones. It also employs a solid phase system for efficient extraction instead of the conventional, less efficient and more labor intensive, liquid-liquid extraction. The inclusion of an internal standard (salicylic acid) improves the precision and reproducibility. It is demonstrated that the method can be used to monitor in vivo clofazimine levels as may be required in formal pharmacokinetic studies or therapeutic drug monitoring. PMID:1299710

  5. Liquid chromatographic analysis and characterization of inorganic nanoclusters

    SciTech Connect

    Wilcoxon, J.P.; Craft, S.A.

    1996-07-01

    We describe the application of the techniques of high pressure liquid chromatography (HPLC) to analyze and characterize various types of inorganic nanoclusters. Both metal and semiconductor nanoclusters were grown in inverse micelles and we demonstrate how the nanoclusters can be separated from the surfactants and other byproducts of the reaction by using a variety of HPLC columns. We also discuss passivation of the cluster surface to prevent aggregation. The HPLC columns separate the clusters based upon a combination of size exclusion and chemical affinity mechanisms and the optical properties of the purified clusters are determined on- line using a variety of detectors. These include a photodiode array for collecting absorbance spectra, a fluorescence detector to monitor luminescence, and a conductivity detector to monitor surface charge on the nanoclusters. We illustrate the analysis of nanoclusters using HPLC by showing data from semiconductor Si, MoS{sub 2} nanoclusters and Au nanoclusters. An extremely novel luminescence was observed from very small metal nanoclusters.

  6. High-pressure liquid chromatographic method for the determination of patulin in apple butter.

    PubMed

    Ware, G M

    1975-07-01

    Patulin is extracted from apple butter samples with ethyl acetate and the extract is cleaned up on a silica gel column, using benzene-ethyl acetate (75+25) as the eluant. High-pressure liquid chromatography, using a 25 cm ZorbaxSil column, isooctane-ethyl ether-acetic acid (750+250+0.5) as the mobile solvent, and a 254 nm ultraviolet detector, is used for the determinative step. Under these conditions, patulin is eluted before 5-hydroxymethylfurfural, a component of apple butter which interferes with other liquid chromatographic and thin layer chromatographic methods. Recoveries of patulin added at levels of 34.6, 138.4, and 276.8 mug/kg ranged from 89.0 to 112.1%. PMID:168176

  7. Red-green-blue fluorescent hollow carbon nanoparticles isolated from chromatographic fractions for cellular imaging

    NASA Astrophysics Data System (ADS)

    Gong, Xiaojuan; Hu, Qin; Paau, Man Chin; Zhang, Yan; Shuang, Shaomin; Dong, Chuan; Choi, Martin M. F.

    2014-06-01

    An as-synthesised hollow carbon nanoparticle (HC-NP) sample has been proved to be a relatively complex mixture, and its complexity can be reduced significantly by high-performance liquid chromatography. An unprecedented reduction in such complexity can reveal fractions of HC-NP with unique luminescence properties. While the UV-vis absorption profile for the HC-NP mixture is featureless, the HC-NP fractions do possess unique absorption bands and specific emission wavelengths. The HC-NP fractions are fully anatomised by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry, displaying their fragmentation mass ion features. The shell thickness and crystal lattices of the selected HC-NP fractions are determined as 6.13, 8.31, 2.22, and 8.66 nm, and 0.37, 0.35, 0.33, and 0.32 nm by transmission electron microscopy, respectively. The fractionated HC-NP show profound differences in emission quantum yield, allowing for brighter HC-NP to be isolated from an apparent low quantum yield mixture. Finally, red, green and blue emissive HC-NP are isolated from the as-synthesised HC-NP sample. They show good photostability and have been demonstrated to be excellent probes for cellular imaging.An as-synthesised hollow carbon nanoparticle (HC-NP) sample has been proved to be a relatively complex mixture, and its complexity can be reduced significantly by high-performance liquid chromatography. An unprecedented reduction in such complexity can reveal fractions of HC-NP with unique luminescence properties. While the UV-vis absorption profile for the HC-NP mixture is featureless, the HC-NP fractions do possess unique absorption bands and specific emission wavelengths. The HC-NP fractions are fully anatomised by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry, displaying their fragmentation mass ion features. The shell thickness and crystal lattices of the selected HC-NP fractions are determined as 6.13, 8.31, 2.22, and 8.66 nm, and 0

  8. A validated high performance liquid chromatographic method for the analysis of Goldenseal.

    PubMed

    Li, Wenkui; Fitzloff, John F

    2002-03-01

    Goldenseal (Hydrastis canadensis L.) has emerged as one of the top ten herbal supplements on the worldwide market. A rapid, simple and validated high performance liquid chromatographic method, with photodiode array detection, has been developed for the analysis of commercial Goldenseal products. Samples were treated by sonication with acidified methanol/water. The method was validated for LOD, LOQ, linearity, reproducibility and recovery with good results. PMID:11902811

  9. Deep liquid-chromatographic purification of uranium extract from technetium

    SciTech Connect

    Volk, V.; Dvoeglazov, K; Podrezova, L.; Vidanov, V.; Pavlyukevich, E.

    2013-07-01

    The recycling of uranium in the nuclear fuel cycle requires the removal of a number of radioactive and stable impurities like {sup 99}Tc from spent fuels. In order to improve the grade of uranium extract purification from technetium the method of liquid chromatography and the apparatus for its performance have been developed. Process of technetium extraction and concentrating in aqueous solution containing reducing agent has been studied on simulated solutions (U-Tc-HNO{sub 3}-30% TBP-isoparM). The dynamic tests of the method have been carried out on the laboratory unit. Solution of diformyl-hydrazine in nitric acid was used as a stationary phase. Silica gel with specific surface of 186 m{sup 2}/g was used as a carrier of the stationary phase. It is shown that the volume of purified extract increases as the solution temperature increases, concentration of reducing agent increases and extract flow rate decreases. It is established that the technetium content in uranium by this method could achieve a value below 0.3 ppm. Some variants of overload and composition of the stationary phase containing the extracted technetium have been offered and tested. It is defined that the method provides reduction of processing medium-active wastes by more than 10 times during finish refining process. (authors)

  10. Liquid chromatographic determination of oxfendazole in swine feeds.

    PubMed

    Shah, G; Bradley, D; Shek, E

    1984-01-01

    A relatively simple analytical method is presented for determination of oxfendazole (2-(methoxycarbonylamino)-5-phenylsulfinyl-benzimidazole) at levels as low as 0.012% in swine feeds, using cation exchange liquid chromatography (LC). The sample was extracted with a solvent mixture of methanol-glacial acetic acid (90 + 10) at 45 degrees C, using a gyrorotory shaker. Plant pigments and other feed excipients were removed using zinc acetate treatment and pH-controlled extraction. Oxfendazole was further separated from the remaining interferences and quantitatively determined by LC on a Partisil SCX column with acetonitrile-0.01M phosphate buffer as mobile phase. The method is stability-specific, linear, precise, and accurate at 80-120% labeled strength (relative standard deviation 0.9-1.7 with mean recovery of 98-99%). Supporting data at a level of 0.0135% oxfendazole in swine feed indicated that this method is capable of complete recovery of oxfendazole from medicated swine feeds. PMID:6469900

  11. CHROMATOGRAPHIC ALTERATION OF A NONIONIC SURFACTANT MIXTURE DURING TRANSPORT IN DENSE NONAQUEOUS PHASE LIQUID CONTAMINATED SEDIMENT (R826650)

    EPA Science Inventory

    Chromatographic alteration of a nonionic surfactant mixture during transport through DNAPL-contaminated aquifer sediment may occur due to differential loss of oligomers to sediment and to dense nonaqueous phase liquid (DNAPL). These losses may significantly alter the solubilizing...

  12. High-performance liquid-chromatographic separation of subcomponents of antimycin-A

    USGS Publications Warehouse

    Abidi, S.L.

    1988-01-01

    Using a reversed-phase high-performance liquid chromatographic (HPLC) technique, a mixture of antimycins A was separated into eight hitherto unreported subcomponents, Ala, Alb, A2a, A2b, A3a, A3b, A4a, and A4b. Although a base-line resolution of the known four major antimycins Al, A2, A3, and A4 was readily achieved with mobile phases containing acetate buffers, the separation of the new antibiotic subcomponents was highly sensitive to variation in mobile phase conditions. The type and composition of organic modifiers, the nature of buffer salts, and the concentration of added electrolytes had profound effects on capacity factors, separation factors, and peak resolution values. Of the numerous chromatographic systems examined, a mobile phase consisting of methanol-water (70:30) and 0.005 M tetrabutylammonium phosphate at pH 3.0 yielded the most satisfactory results for the separation of the subcomponents. Reversed-phase gradient HPLC separation of the dansylated or methylated antibiotic compounds produced superior chromatographic characteristics and the presence of added electrolytes was not a critical factor for achieving separation. Differences in the chromatographic outcome between homologous and structural isomers were interpretated based on a differential solvophobic interaction rationale. Preparative reversed-phase HPLC under optimal conditions enabled isolation of pure samples of the methylated antimycin subcomponents for use in structural studies.

  13. Evaluation of coverage, retention patterns, and selectivity of seven liquid chromatographic methods for metabolomics.

    PubMed

    Wernisch, Stefanie; Pennathur, Subramaniam

    2016-09-01

    Liquid chromatography-mass spectrometry-based metabolomics studies require highly selective and efficient chromatographic techniques. Typically employed reversed-phase (RP) methods fail to target polar metabolites, but the introduction of hydrophilic interaction liquid chromatography (HILIC) is slow due to perceived issues of reproducibility and ruggedness and a limited understanding of the complex retention mechanisms. In this study, we present a comparison of the chromatographic performance of a traditional RP-C18 column with zwitterionic, amide-, alkyl diol-, and aminoalkyl-based HILIC and mixed-mode columns. Our metabolite library represents one of the largest analyte sets available and consists of 764 authentic metabolite standards, including amino acids, nucleotides, sugars, and other metabolites, representing all major biological pathways and commonly observed exogenous metabolites (drugs). The coverage, retention patterns, and selectivity of the individual methods are highly diverse even between conceptually related HILIC methods. Furthermore, we show that HILIC sorbents having highly orthogonal selectivity and specificity enhance the coverage of major metabolite groups in (semi-) targeted applications compared to RP. Finally, we discuss issues encountered in the analysis of biological samples based on the results obtained with human plasma extracts. Our results demonstrate that fast and highly reproducible separations on zwitterionic columns are feasible, but knowledge of analyte properties is essential to avoid chromatographic bias and exclusion of key analytes in metabolomics studies. Graphical Abstract The chromatographic parameters of 764 authentic metabolite standards provide the basis for a comparison of coverage, selectivity and orthogonality of 7 reversed-phase (RP), mixed-mode (MM) and hydrophilic interaction liquid chromatography (HILIC) methods. PMID:27370688

  14. GAS CHROMATOGRAPH-BASED SYSTEM FOR MEASURING THE METHANE FRACTION OF DIESEL ENGINE HYDROCARBON EMISSIONS

    EPA Science Inventory

    An instrument has been developed (termed the 'methane analytical system') enabling diesel methane emissions to be quatified separately from total unburned hydrocarbon emissions. The instrument employed gas chromatographic principles whereby a molecular sieve column operating isot...

  15. Liquid chromatographic method for the determination of rizatriptan in human plasma.

    PubMed

    Chen, Jun; Jiang, Xinguo; Jiang, Wenming; Mei, Ni; Gao, Xiaoling; Zhang, Qizhi

    2004-06-01

    A high-performance liquid chromatographic (HPLC) method with fluorescence detection has been developed for the determination of rizatriptan in human plasma. Following a single-step liquid-liquid extraction with methyl tertiarybutyl ether, the analytes were separated using a mobile phase consisting of 0.05% (v/v) triethylamine in water (adjusting to pH 2.75 with 85% phosphoric acid) and acetonitrile (92:8, v/v). Fluorescence detection was performed at an excitation wavelength of 225nm and an emission wavelength of 360nm. The linearity for rizatriptan was within the concentration range of 0.5-50ng/ml. The intra- and inter-day precisions of the method were not more than 8.0%. The lower limit of quantification (LLOQ) was 0.5ng/ml for rizatriptan. The method was sensitive, simple and repeatable enough to be used in pharmacokinetic studies. PMID:15113554

  16. Gas and liquid chromatographic analyses of nimodipine calcium antagonist in blood plasma and cerebrospinal fluid.

    PubMed

    Krol, G J; Noe, A J; Yeh, S C; Raemsch, K D

    1984-01-13

    Gas (GC) and liquid chromatographic (LC) assay procedures were developed for analysis of nimodipine (1,4-dihydropyridine calcium antagonist, BAY e 9736) in blood plasma at low nanogram concentration levels. To avoid decomposition during gas chromatography, nimodipine was oxidized to nimodipine pyridine (P) analogue before it was chromatographed on the OV-17 column and quantitated using an electron-capture detector. In contrast, the LC procedure involved chromatographic separation and quantitation of the underivatized nimodipine and of the endogenous P analogue using a 3-micron Spherisorb ODS column and UV detection. The same plasma extract and three alternative internal standards were used for both assays. Taking into consideration the fact that the GC assay result includes endogenous P analogue as well as nimodipine, good correlation between GC and LC assay data was obtained. Comparison of the results observed with the two procedures confirmed the accuracy of each procedure and provided an alternative when one of the assay results was subject to patient plasma constituent interference. The LC assay was also used for analysis of the demethylated metabolites of nimodipine. To detect sub-nanogram concentrations of nimodipine in cerebrospinal fluid a combined LC-GC procedure using an LC clean-up step and a GC quantitation step was also developed. The above GC and LC procedures were used to obtain preliminary pharmacokinetic data. PMID:6707134

  17. Application of Sigmoidal Transformation Functions in Optimization of Micellar Liquid Chromatographic Separation of Six Quinolone Antibiotics.

    PubMed

    Hadjmohammadi, Mohammadreza; Salary, Mina

    2016-03-01

    A chemometrics approach has been used to optimize the separation of six quinolone compounds by micellar liquid chromatography (MLC). A Derringer's desirability function, a multicriteria decision-making (MCDM) method, was tested for evaluation of two different measures of chromatographic performance (resolution and analysis time). The effect of three experimental parameters on a chromatographic response function (CRF) expressed as a product of two sigmoidal desirability functions was investigated. The sigmoidal functions were used to transform the optimization criteria, resolution and analysis time into the desirability values. The factors studied were the concentration of sodium dodecyl sulfate, butanol content and pH of the mobile phase. The experiments were done according to the face-centered cube central composite design, and the calculated CRF values were fitted to a polynomial model to correlate the CRF values with the variables and their interactions. The developed regression model showed good descriptive and predictive ability (R(2) = 0.815, F = 6.919, SE = 0.038, [Formula: see text]) and used, by a grid search algorithm, to optimize the chromatographic conditions for the separation of the mixture. The efficiency of prediction of polynomial model was confirmed by performing the experiment under the optimal conditions. PMID:26590234

  18. High-performance liquid chromatographic characterization of some medical plant extracts used in cosmetic formulas.

    PubMed

    Schulz, H; Albroscheit, G

    1988-06-17

    Rapid and reliable methods are presented for the characterization of biologically active and/or characteristic constituents in aqueous extracts of Hamamelis virginiana, Matricaria chamomilla, Achillea millefolium, Thymus vulgaris, Althaea officinalis and Cinchonia spp. Prior to high-performance liquid chromatographic (HPLC) separation a clean-up step was performed using a solid-phase extraction system. The purified extracts were analysed by HPLC coupled with a diode-array detector and a fluorescence detector. In some instances, previously unreported components of the aqueous plant extracts were found. PMID:3417826

  19. Reversed-phase high-performance liquid chromatographic method for the assay of oxytetracycline.

    PubMed

    Barnes, W N; Ray, A; Bates, L J

    1985-10-25

    The British Pharmacopoeia monograph for oxytetracycline calcium describes an high-performance liquid chromatographic (HPLC) assay which requires packing of the column by the analyst. Presented in this report is an HPLC method for the assay of oxytetracycline which employs a commercially available reversed-phase column and a solvent system which gives improved separation of the antibiotic from common impurities. Results obtained using this method for both bulk and dosage forms of oxytetracycline are in accord with the results of the microbiological assays. PMID:4086631

  20. A trade off between separation, detection and sustainability in liquid chromatographic fingerprinting.

    PubMed

    Funari, Cristiano S; Carneiro, Renato L; Cavalheiro, Alberto J; Hilder, Emily F

    2014-08-01

    It is now recognized that analytical chemistry must also be a target for green principles, in particular chromatographic methods which typically use relatively large volumes of hazardous organic solvents. More generally, high performance liquid chromatography (HPLC) is employed routinely for quality control of complex mixtures in various industries. Acetonitrile and methanol are the most commonly used organic solvents in HPLC, but they generate an impact on the environment and can have a negative effect on the health of analysts. Ethanol offers an exciting alternative as a less toxic, biodegradable solvent for HPLC. In this work we demonstrate that replacement of acetonitrile with ethanol as the organic modifier for HPLC can be achieved without significantly compromising analytical performance. This general approach is demonstrated through the specific example analysis of a complex plant extract. A benchmark method employing acetonitrile for the analysis of Bidens pilosa extract was statistically optimized using the Green Chromatographic Fingerprinting Response (GCFR) which includes factors relating to separation performance and environmental parameters. Methods employing ethanol at 30 and 80°C were developed and compared with the reference method regarding their performance of separation (GCFR) as well as by a new metric, Comprehensive Metric to Compare Liquid Chromatography Methods (CM). The fingerprint with ethanol at 80°C was similar to or better than that with MeCN according to GCFR and CM. This demonstrates that temperature may be used to replace harmful solvents with greener ones in HPLC, including for solvents with significantly different physiochemical properties and without loss in separation performance. This work offers a general approach for the chromatographic analysis of complex samples without compromising green analytical chemistry principles. PMID:24952659

  1. Decomposition of pilocarpine eye drops assessed by a highly efficient high pressure liquid chromatographic method.

    PubMed

    Kuks, P F; Weekers, L E; Goldhoorn, P B

    1990-10-19

    A rapid high-resolution high pressure liquid chromatographic method was developed for assaying pilocarpine. Pilocarpine in ophthalmic solutions decomposes fairly rapidly to give isopilocarpine, pilocarpic acid and isopilocarpic acid. The quality of an ophthalmic solution can be assessed by assaying these decomposition products. Existing high pressure liquid chromatographic methods suffer from long analysis times and poor resolution. The new method uses as the mobile phase 6 ml/l of triethylamine in water (pH 2.3, adjusted with 85% phosphoric acid) at a flow of 1.5 ml/min and as the stationary phase a C18-silica 125 x 4.6 mm column. 2-Amino-1-phenyl-1,3-propanediol is used as an internal standard. Complete separation was obtained within 8 min. Pilocarpine eye drops were stored under different conditions and then analysed for decomposition products. During heat treatment, decomposition to isopilocarpine predominated over decomposition to pilocarpic or isopilocarpic acid. However, when stored at room temperature or in a refrigerator, formation of pilocarpic acid clearly prevailed. Thus, from assessment of decomposition products, the cause of decomposition can be established. PMID:2255589

  2. Fully automated high-performance liquid chromatographic assay for the analysis of free catecholamines in urine.

    PubMed

    Said, R; Robinet, D; Barbier, C; Sartre, J; Huguet, C

    1990-08-24

    A totally automated and reliable high-performance liquid chromatographic method is described for the routine determination of free catecholamines (norepinephrine, epinephrine and dopamine) in urine. The catecholamines were isolated from urine samples using small alumina columns. A standard automated method for pH adjustment of urine before the extraction step has been developed. The extraction was performed on an ASPEC (Automatic Sample Preparation with Extraction Columns, Gilson). The eluate was collected in a separate tube and then automatically injected into the chromatographic column. The catecholamines were separated by reversed-phase ion-pair liquid chromatography and quantified by fluorescence detection. No manual intervention was required during the extraction and separation procedure. One sample may be run every 15 min, ca. 96 samples in 24 h. Analytical recoveries for all three catecholamines are 63-87%, and the detection limits are 0.01, 0.01, and 0.03 microM for norepinephrine, epinephrine and dopamine, respectively, which is highly satisfactory for urine. Day-to-day coefficients of variation were less than 10%. PMID:2277100

  3. Determination of calcium stearate in polyolefin samples by gas chromatographic technique after performing dispersive liquid-liquid microextraction.

    PubMed

    Ranji, Ali; Ghorbani Ravandi, Mahboobeh; Farajzadeh, Mir Ali

    2008-05-01

    In this study, a gas chromatographic method is presented for the determination of calcium stearate after its conversion to stearic acid in a polymeric matrix. A solution of hydrochloric acid in 2-propanol is used as an extracting solvent of calcium stearate and its converter to stearic acid. For stearic acid preconcentration before its injection to a separation system, a recently presented extraction method, dispersive liquid-liquid microextraction, using carbon tetrachloride as an extracting solvent is used. Finally, 1 microL of the organic phase collected at the bottom of a conical test tube after centrifuging is injected into a gas chromatograph (GC) for quantification. This method has a relatively broad linear dynamic range (50 - 2000 mg/L) with a limit of detection (LOD) of 15 mg/L for stearic acid in solution. The LOD of the proposed method in a polymeric sample using 10 mg of polymer is 60 ppm as calcium stearate. Some effective parameters, such as the time and temperature of heating, the concentration of hydrochloric acid and the volume of distilled water, were studied. PMID:18469468

  4. Simple high-performance liquid chromatographic method for the determination of medroxyprogesterone acetate in human plasma.

    PubMed

    Read, J; Mould, G; Stevenson, D

    1985-06-14

    The high-performance liquid chromatographic (HPLC) method was developed as a simple, reliable alternative to available methods for measuring plasma concentrations of medroxyprogesterone acetate (MPA). The HPLC method has been successfully automated and is suitable for the rapid, inexpensive analysis of large batches of plasma samples. The best approach involves a solvent extraction followed by HPLC separation and analysis. MPA can be efficiently extracted, at all pH values, by nonpolar solvents. The Spherisorb 5-ODS2 HPLC column provides excellent separation of MPA from endogenous steroids of similar structure and from extraneous plasma blank peaks. A batch of 30-40 samples can be prepared by HPLC analysis in 2-3 hours, with a chromatographic run time of 10 minutes/sample. Calibration curves between 5-250 ng/ml show a good correlation between peak height ratio and MPA concentration, even at low levels. Plasma concentrations of MPA in patients receiving 1 g/day were between 12.6-270 ng/ml in this study, suggesting that the sensitivity of this method, 10 ng/ml, is sufficient for monitoring therapeutic concentrations of MPA. The results show a wide individual variation in plasma concentrations following similar dosing schedules--a finding reported by other workers. PMID:3161906

  5. Mass spectrometric and high-performance liquid chromatographic studies of medroxyprogesterone acetate metabolites in human plasma.

    PubMed

    Sturm, G; Häberlein, H; Bauer, T; Plaum, T; Stalker, D J

    1991-01-01

    Medroxyprogesterone acetate (MPA) treatment has been shown to exert several beneficial effects in cancer patients. It has been suggested that such effects are due in part to the metabolites derived from MPA in vivo. The first results are reported on the identification of 2 alpha-hydroxy- and 21-hydroxy-MPA, 20-dihydro-MPA, 17 alpha-acetoxy-2 alpha,3 beta-dihydroxy-6 alpha-methylpregn-1,4-dien-20-one and two X,21-dihydroxy-MPAs, one of them presumably being 6 alpha-hydroxymethyl-21-hydroxy-MPA, in patient's plasma by high-performance liquid chromatographic (HPLC), gas chromatographic-mass spectrometric and NMR methods. Additionally, the presence of other metabolites such as di- and tetrahydro-MPAs and 6,21-dihydroxy-MPA, found in urine and other samples, was demonstrated in plasma. For routine clinical examinations an HPLC method is described for determination of, e.g., the unreduced MPA metabolite group in Sep-Pak-ODS column extracts of patients' plasma. PMID:1827448

  6. Direct zonal liquid chromatographic method for the kinetic study of actinomycin-DNA binding.

    PubMed

    Vidal-Madjar, Claire; Florentina, Cañada-Cañada; Gherghi, Ioanna; Jaulmes, Alain; Pantazaki, Anastasia; Taverna, Myriam

    2004-07-01

    The binding of an anticancer drug (actinomycin D or ACTD) to double-stranded DNA (dsDNA) was studied by means of high-performance liquid chromatography (HPLC). ACTD is an antitumor antibiotic containing one chromophore group and two pentapeptidic lactone cycles that binds dsDNA. Incubations of ACTD with DNA were performed at physiological pH. The complexed and free ligand concentrations of the mixture were quantified at 440 nm from their separation on a size-exclusion chromatographic (SEC) column using the same buffer for the elution and the sample incubation. The DNA and the ACTD-DNA complexes were eluted at the column exclusion volume while the ligand was retained on the support. An apparent binding curve was obtained by plotting the amount emerging at the exclusion column volume against that eluted at free ACTD retention volume. A dissociating effect was evidenced and the binding parameters were significantly different from those obtained at equilibrium by visible absorbance titration. The equilibrium binding parameters determined by absorption spectroscopy were used as starting data in the numerical simulations of the chromatographic process. The results showed a strong dependency of the apparent binding parameters on the reaction kinetics. Finally the comparison of the apparent binding curve obtained from the HPLC experiments and from the numerical simulations permitted an evaluation of the dissociation rate constant (kd = 0.004 s(-1)). PMID:15296384

  7. Liquid chromatographic determination of residual hydrogen peroxide in pharmaceutical excipients using platinum and wired enzyme electrodes.

    PubMed

    Huang, Tiehua; Garceau, Michelle E; Gao, Ping

    2003-04-10

    Hydrogen peroxide (H(2)O(2)) is a chemically reactive reagent that can oxidize and degrade many pharmaceutical compounds under normal conditions. Unfortunately, H(2)O(2) is often introduced into pharmaceutical excipients during manufacturing and it may significantly affect the chemical stability of drugs in formulations. Thus, a sensitive analytical method for determination of residual H(2)O(2) in excipients is of importance in formulation development and product quality control. A liquid chromatographic system with a dual channel electrochemical detector (LCEC) was equipped with either a platinum electrode or a wired peroxidase electrode for determination of H(2)O(2). The excipient (0.1 g) was dissolved in 10 ml of mobile phase and 5 microl of the dissolved solution was directly injected. The chromatographic run time for each sample was 1 min with a detection limit of 10 ng/ml (S/N=5) using the platinum electrode and 1 ng/ml (S/N=5) using the wired enzyme coated electrode, respectively. The peak purity was assured by comparing the peak ratios at different potentials for both the standard and the samples. The H(2)O(2) levels in different batches of PVP, PEG, and other surfactants from different manufacturers were determined and the values ranged from 0 to 244 ppm. The LCEC method is exceptionally fast, accurate and convenient for quantitation of low levels of residual H(2)O(2) in pharmaceutical formulation excipients. PMID:12667936

  8. Quantitative Metabolome Analysis Based on Chromatographic Peak Reconstruction in Chemical Isotope Labeling Liquid Chromatography Mass Spectrometry.

    PubMed

    Huan, Tao; Li, Liang

    2015-07-21

    Generating precise and accurate quantitative information on metabolomic changes in comparative samples is important for metabolomics research where technical variations in the metabolomic data should be minimized in order to reveal biological changes. We report a method and software program, IsoMS-Quant, for extracting quantitative information from a metabolomic data set generated by chemical isotope labeling (CIL) liquid chromatography mass spectrometry (LC-MS). Unlike previous work of relying on mass spectral peak ratio of the highest intensity peak pair to measure relative quantity difference of a differentially labeled metabolite, this new program reconstructs the chromatographic peaks of the light- and heavy-labeled metabolite pair and then calculates the ratio of their peak areas to represent the relative concentration difference in two comparative samples. Using chromatographic peaks to perform relative quantification is shown to be more precise and accurate. IsoMS-Quant is integrated with IsoMS for picking peak pairs and Zero-fill for retrieving missing peak pairs in the initial peak pairs table generated by IsoMS to form a complete tool for processing CIL LC-MS data. This program can be freely downloaded from the www.MyCompoundID.org web site for noncommercial use. PMID:26086729

  9. Reverse phase liquid chromatographic assay for calcium pantothenate in multivitamin preparations and raw materials.

    PubMed

    Timmons, J A; Meyer, J C; Steible, D J; Assenza, S P

    1987-01-01

    A reverse phase liquid chromatographic (LC) method has been developed for the assay of calcium pantothenate in commercial multivitamin tablet formulations and raw materials. The assay was validated according to the Pharmaceutical Manufacturers Association Quality Control HPLC Committee guidelines. The chromatographic system includes a C-18 column and a mobile phase consisting of 0.25M sodium phosphate buffer, pH 2.5, and acetonitrile (97 + 3 v/v). The column effluent is monitored by UV detection at 205 nm. The sample preparation involves only extraction in water followed by filtration. The method is stability-indicating with a detection limit of approximately 50 ng/mL of the calcium pantothenate in the samples. The system is linear from at least 0.02 to 0.10 mg/mL. The mean recovery of spiked placebos ranged from 98.7 to 99.8%. The within-day precision of the assay on finished products (N = 6) ranged from 0.3 to 2.0% CV. A system suitability criterion for resolution is based on the separation between calcium pantothenate and 2 closely eluting compounds, saccharin and a saccharin degradation product, 2-sulfamoylbenzoic acid. PMID:3610964

  10. Rapid gas-liquid chromatographic method for determination of sulfathiazole in swine feed.

    PubMed

    Munns, R K; Roybal, J E

    1983-03-01

    A gas-liquid chromatographic (GLC) method for determining residues of sulfathiazole (STZ) in swine feed has been developed. Feed is extracted first with acetone and then with ammonia-acetone. STZ is isolated from other feed extractives on a Sephadex LH-20 column with methanol-toluene. The sulfa residues are methylated with diazomethane, and the eluate is evaporated to dryness. A solution containing an internal standard of methyl sulfasymazine is used to dilute the sample before injection onto an OV-25 GLC column. The precision of the method was determined by assaying 10 sets of feed spiked at 0.5, 1, 2, and 5 ppm STZ. The mean recoveries and coefficients of variation were 90.2 (5.90), 89.5 (4.67), 87.4 (5.62), and 87.7% (4.29), respectively. The critical steps of the method, including the stability of STZ, were also determined. PMID:6853414

  11. Rapid gas-liquid chromatographic method for determination of sulfamethazine in swine feed.

    PubMed

    Munns, R K; Roybal, J E

    1982-09-01

    A gas-liquid chromatographic method is described for the quantitative determination of trace amounts of sulfamethazine in swine feed. Sulfamethazine is extracted in ammoniated acetone and isolated from other extractants on a Sephadex LH-20 column. The eluate is methylated with diazomethane and evaporated to dryness. The residue is dissolved in a solvent containing an internal standard of methyl sulfasymazine before being injected onto an OV-25 GLC column. An estimation of precision was established by assaying 10 sets of swine feed fortified with 0.5, 1,2, and 5 ppm SMZ. Mean recoveries were 96.0, 94.3, 93.5, and 94.0%, respectively, with an average coefficient of variation of 3.07%. The critical steps and ruggedness of the method were also determined. PMID:7130074

  12. Liquid chromatographic determination of five benzoylurea insecticides in fruit and vegetables.

    PubMed

    Gamón, M; Saez, A; Pelegrí, R; Peris, I; de la Cuadra, J G; Coscollá, R

    1998-01-01

    A liquid chromatographic (LC) method was developed to determine 5 benzoylureas--diflubenzuron, hexaflumuron, teflubenzuron, flufenozuron, and lufenuron--in peppers, tomatoes, eggplants, cucumbers, and oranges. Preparation of samples involve extraction with acetone and partitioning into dichloromethane-petroleum ether. A portion of this extract is cleaned up with a solid-phase extraction aminopropyl disposable column. With LC analysis using an RP-8-DB microbore column, acetonitrile-water (70 + 30, v/v) as mobile phase, and photodiode array detection at 254 nm, recovery and repeatability data were collected for the 5 benzoylureas on 4 vegetables and citrus in the range 0.04-2.0 mg/kg. Validated limits of detection and quantitation were 0.01 and 0.04 mg/kg, respectively. The method is reliable for routine analysis of vegetables and fruits. PMID:9772746

  13. High-performance liquid chromatographic determination of methyl anthranilate, hydroxymethylfurfural and related compounds in honey.

    PubMed

    Nozal, M J; Bernal, J L; Toribio, L; Jiménez, J J; Martín, M T

    2001-05-11

    A high-performance liquid chromatographic method for determining 5-hydroxymethyl-2-furaldehyde (hydroxymethylfurfural), 2-furaldehyde (furfural), furan-2-carboxylic acid (2-furoic acid), furan-3-carboxylic acid (3-furoic acid), furan-3-carboxaldehyde (3-furaldehyde) and 2-aminobenzoic acid methyl ester (methyl anthranilate) in honey and honeydew samples is described. To prevent matrix interference and to isolate the compounds, a clean-up step which implies a solid-phase extraction on polymeric cartridges and an elution with 0.5 ml methanol is recommended. The compounds are separated on a reversed-phase column with a gradient of (A) 1% aqueous acetic acid-acetonitrile (97:3, v/v) and (B) acetonitrile-water (50:50, v/v), with UV detection at 250 nm. The method is applied to the analysis of samples from different botanical origin. PMID:11403496

  14. Liquid chromatographic determination of residual isocyanate monomers in plastics intended for food contact use.

    PubMed

    Damant, A P; Jickells, S M; Castle, L

    1995-01-01

    A liquid chromatographic (LC) method was developed for the analysis of 10 isocyanates in polyurethane articles and laminates intended for food use. Residual isocyanates are extracted by dichloromethane with concurrent derivatization by 9-(methylaminomethyl)anthracene. The resultant derivatives are analyzed by reversed-phase LC with fluorescence detection. Separation of the isocyanates was studied and optimized. Quantitation uses 1-naphthyl isocyanate as internal standard and standard addition to the food package. Validation demonstrated the method to have good precision (+/- 2-5%) and recovery (83-95%) for samples spiked with isocyanates at 0.1 mg/kg. The limit of detection was 0.03 mg/kg. Analysis of 19 commercial polyurethane or laminate food packages demonstrated that the method was not prone to interferences. Residues of diphenylmethane-4,4'-diisocyanate were detected in 5 packages and ranged from 0.14 to 1.08 mg/kg. PMID:7756886

  15. High-performance liquid chromatographic determination of naltrexone in plasma of hemodialysis patients.

    PubMed

    Kambia, K; Bah, S; Dine, T; Azar, R; Odou, P; Gressier, B; Luyckx, M; Brunet, C; Ballester, L; Cazin, M; Cazin, J C

    2000-05-01

    A simple, sensitive, selective and reliable reversed-phase high-performance liquid chromatographic (HPLC) method with UV detection is described for the determination of naltrexone in plasma samples. Naltrexone and the internal standard, naloxone, were isolated from plasma either with a liquid-liquid extraction method using ethyl acetate or with a solid-phase extraction method using Sep-Pack C18 cartridge before chromatography. The extracts were dried under a stream of nitrogen and the samples were reconstituted in the mobile phase, then 20 microL were injected on a Waters Symmetry C18 column (5 microm particle size, 4.6 x 150 mm). The mobile phase consisted of 0.06% triethylamine (pH 2.8)-acetonitrile (92:8, v/v) pumped at 1 mL/min. The peak-area ratio versus plasma concentration was linear over the range of 10-500 ng/mL and the detection limit was less than 8 ng/mL. Quantification was by ultra-violet detection at 204 nm. The present method was applied to the determination of the plasma concentration of naltrexone in dialyzed patients. Patients (n = 8) with severe generalized pruritus received 50 mg of naltrexone orally per day for 2 weeks. The variability in the therapeutic response in treated patients required plasma concentration investigations of this opioid antagonist. PMID:10850617

  16. Simultaneous liquid-chromatographic determination of vitamin K1 and vitamin E in serum.

    PubMed

    Cham, B E; Roeser, H P; Kamst, T W

    1989-12-01

    We describe a high-performance liquid chromatographic procedure for the simultaneous measurement of vitamins K1 and E in human serum. Delipidated human serum (free of vitamins K1 and E) was used to make standard solutions of these vitamins, and cetyl naphthoate and alpha-tocopheryl acetate were the internal standards for vitamin K1 and vitamin E, respectively. A simple, novel separation method utilizing liquid-liquid partition chromatography was used as a preparative "clean-up" procedure. Cetyl naphthoate and vitamin K1 (after post-column reduction) were detected by fluorescence, alpha-tocopheryl acetate and vitamin E by ultraviolet absorption. Sensitivity (detection limit) of the assay was 30 pg for vitamin K1 and 5 ng for vitamin E per injection. The method is specific, precise, and more rapid than previously described procedures. Within- and between-assay CVs were 8.1% and 12.9%, respectively, for vitamin K1; 3.5% and 6.0%, respectively, for vitamin E. Analytical recoveries of vitamins K1 and E were 80% and 93%, respectively, from serum and from delipidated serum (standards). The average neonatal serum concentration of vitamin K1 was 83 ng/L, 2.5 mg/L for vitamin E; for normolipidemic adults, the values were 343 ng/L and 7.9 mg/L, respectively, and for hyperlipidemic adults, 541 ng/L and 11.1 mg/L, respectively. PMID:2591045

  17. Liquid chromatographic method for determination of water in soils and the optimization of anion separations by capillary zone electrophoresis

    SciTech Connect

    Benz, N.

    1994-10-01

    A liquid chromatographic method for the determination of water in soil or clay samples is presented. In a separate study, the optimization of electrophoretic separation of alkylated phenolate ions was optimized by varying the pH and acetonitrile concentration of the buffer solutions.

  18. INTERFACE OF A REVERSE-PHASE HIGH-PERFORMANCE LIQUID CHROMATOGRAPH WITH A DIFFUSE REFLECTANCE FOURIER TRANSFORM INFRARED SPECTROMETER

    EPA Science Inventory

    An approach to the interface of a reverse-phase high-performance liquid chromatograph and a Fourier transform infrared spectrometer has been developed in which the solutes eluting from the column are continuously extracted into dichloromethane. The application of both flow cell a...

  19. Development and validation of a hydrophilic interaction liquid chromatographic method for determination of aromatic amines in environmental water

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A simple, precise, and accurate hydrophilic interaction liquid chromatographic (HILIC) method has been developed for the determination of 5 aromatic amines in environmental water samples. Chromatography was carried out on a bare silica column, using a mixture of acetonitrile: phosphate buffer (10 mM...

  20. 34 GHz EPR FTIR spectra of chromatographically separated Boscan asphaltene fractions

    SciTech Connect

    Malhotra, V.M. ); Buckmaster, H.A. )

    1989-03-01

    The authors report on their re-examination of the 34 GHz and Fourier transform infrared (FTIR) measurements on three fractions of Boxcan asphaltene separated by the gel permeation chromatography (GPC) technique. The authors attempted to determine various types of vanadium coordination in GPC fractions by their partial combustion and subsequent EPR AND FTIR measurements.

  1. Application of Analytical Quality by Design concept for bilastine and its degradation impurities determination by hydrophilic interaction liquid chromatographic method.

    PubMed

    Terzić, Jelena; Popović, Igor; Stajić, Ana; Tumpa, Anja; Jančić-Stojanović, Biljana

    2016-06-01

    This paper deals with the development of hydrophilic interaction liquid chromatographic (HILIC) method for the analysis of bilastine and its degradation impurities following Analytical Quality by Design approach. It is the first time that the method for bilastine and its impurities is proposed. The main objective was to identify the conditions where an adequate separation in minimal analysis duration could be achieved within a robust region. Critical process parameters which have the most influence on method performance were defined as acetonitrile content in the mobile phase, pH of the aqueous phase and ammonium acetate concentration in the aqueous phase. Box-Behnken design was applied for establishing a relationship between critical process parameters and critical quality attributes. The defined mathematical models and Monte Carlo simulations were used to identify the design space. Fractional factorial design was applied for experimental robustness testing and the method is validated to verify the adequacy of selected optimal conditions: the analytical column Luna(®) HILIC (100mm×4.6mm, 5μm particle size); mobile phase consisted of acetonitrile-aqueous phase (50mM ammonium acetate, pH adjusted to 5.3 with glacial acetic acid) (90.5:9.5, v/v); column temperature 30°C, mobile phase flow rate 1mLmin(-1), wavelength of detection 275nm. PMID:27131148

  2. Rayleigh light scattering detection of three α1-adrenoceptor antagonists coupled with high performance liquid chromatograph

    NASA Astrophysics Data System (ADS)

    Li, Ai Ping; Peng, Huanjun; Peng, Jing Dong; Zhou, Ming Qiong; Zhang, Jing

    2015-08-01

    Herein, a Rayleigh light-scattering (RLS) detection method combined with high performance liquid chromatograph (HPLC) without any post-column probe was developed for the separation and determination of three α1-adrenoceptor antagonists. The quantitative analysis is benefiting from RLS signal enhancement upon addition of methanol which induced molecular aggregation to form an hydrophobic interface between aggregates and water that produce a sort of superficial enhanced scattering effect. A good chromatographic separation among the compounds was achieved using a Gemini 5u C18 reversed phase column (250 mm × 4.6 mm; 4 μm) with a mobile phase consisting of methanol and ammonium acetate-formic acid buffer solution (25 mM; pH = 3.0) at the flow rate of 0.7 mL min-1. The RLS signal was monitored at λex = λem = 354 nm. A limit of detection (LOD) of 0.065-0.70 μg L-1 was reached and a linear range was found between peak height and concentration in the range of 0.75-15 μg L-1 for doxazosin mesylate (DOX), 0.075-3.0 μg L-1 for prazosin hydrochloride (PRH), and 0.25-5 μg L-1 for terazosin hydrochloride (TEH), with linear regression coefficients all above 0.999. Recoveries from spiked urine samples were 88.4-99.0% which is within acceptable limits. The proposed method is convenient, reliable and sensitive which has been used successfully in human urine samples.

  3. A high-performance liquid chromatographic determination of major phenolic compounds in tobacco smoke

    SciTech Connect

    Risner, C.H.; Cash, S.L. )

    1990-05-01

    A high-performance liquid chromatographic (HPLC) method is developed that simultaneously quantifies the dihydroxy compounds hydroquinone, resorcinol, and catechol and the monohydroxy compounds phenol, m + p-cresol and o-cresol in cigarette smoke. Particulate matter samples collected on Cambridge pads and in impingers by conventional trapping techniques are simply (no derivatization required) subjected to reversed-phase gradient liquid chromatography. Samples of both mainstream and sidestream smoke can be analyzed. Selective fluorescence detection is used to monitor the mobile phase effluent, by which these phenolic compounds are detected in the nanogram range. The detector response is linear, overall precision is good, and recoveries are greater than 95 percent. The total run time, excluding extraction, is one hour. The procedure has been applied to tobacco products whose smoke contains varying amounts of these phenols. Kentucky Reference Cigarette 1R4F was found to contain substantially more of these compounds than a new cigarette that heats but does not burn tobacco (New Cigarette). The method is compared with other procedures used to determine phenolics in cigarette smoke.

  4. Comprehensive two-dimensional liquid chromatographic analysis of rooibos (Aspalathus linearis) phenolics.

    PubMed

    Beelders, Theresa; Kalili, Kathithileni M; Joubert, Elizabeth; de Beer, Dalene; de Villiers, André

    2012-07-01

    Rooibos tea is an unique beverage prepared from unfermented and fermented plant material of the endemic Cape fynbos plant, Aspalathus linearis. The well-known health-promoting benefits of rooibos are partly attributed to its phenolic composition. Detailed investigation of the minor phenolic constituents of rooibos is, however, hampered by the limitations associated with conventional HPLC methods used for its analysis. In this study, the applicability of comprehensive two-dimensional liquid chromatographic methods for the in-depth analysis of rooibos phenolics was investigated. Phenolic compounds were separated according to polarity by hydrophilic interaction chromatography (HILIC) in the first dimension, whilst reversed-phase liquid chromatography (RP-LC) provided separation according to hydrophobicity in the second dimension. Ultraviolet photodiode array and electrospray ionisation mass spectrometry were used to identify phenolic compounds. Comprehensive HILIC × RP-LC demonstrated its applicability for the analysis of a diverse range of phenolic compounds in unfermented and fermented rooibos samples, in which large qualitative differences in the phenolic composition were established. The combination of these orthogonal separations provided a significant improvement in resolution, as exemplified by practical peak capacities in excess of 2000 and 500 for off-line and on-line methods, respectively. PMID:22807363

  5. High-performance liquid chromatographic assays for protoporphyrinogen oxidase and ferrochelatase in human leucocytes.

    PubMed

    Guo, R; Lim, C K; Peters, T J

    1991-05-31

    Rapid, sensitive and specific high-performance liquid chromatographic assays are described for protoporphyrinogen oxidase and ferrochelatase in human leucocytes. The enzyme reaction products were separated and quantitated by reversed-phase high-performance liquid chromatography with fluorescence detection. The optimal pH for the protoporphyrinogen oxidase assay was 8.6 and the Michaelis constant for protoporphyrinogen IX was 9.78 +/- 0.96 microM (mean +/- S.D.). The mean (+/- S.D.) activity of protoporphyrinogen oxidase in fourteen apparently healthy subjects was 0.146 +/- 0.023 nmol protoporphyrin IX per min per mg protein. In one patient with variegate porphyria, the activity was 0.028 nmol protoporphyrin IX per min per mg protein. The optimal pH for ferrochelatase was 7.4 and with protoporphyrin and Zn2+ as substrates, the Michaelis constants were 1.49 and 8.33 microM, respectively. The mean activity of ferrochelatase in ten control subjects was 0.24 nM Zn-protoporphyrin or 2.05 nM Zn-mesoporphyrin formed per h per mg protein. PMID:1939451

  6. [Development of an automatic vacuum liquid chromatographic device and its application in the separation of the components from Schisandra chinensis (Turz) Baill].

    PubMed

    Zhu, Jingbo; Liu, Baoyue; Shan, Shibo; Ding, Yanl; Kou, Zinong; Xiao, Wei

    2015-08-01

    In order to meet the needs of efficient purification of products from natural resources, this paper developed an automatic vacuum liquid chromatographic device (AUTO-VLC) and applied it to the component separation of petroleum ether extracts of Schisandra chinensis (Turcz) Baill. The device was comprised of a solvent system, a 10-position distribution valve, a 3-position changes valve, dynamic axis compress chromatographic columns with three diameters, and a 10-position fraction valve. The programmable logic controller (PLC) S7- 200 was adopted to realize the automatic control and monitoring of the mobile phase changing, column selection, separation time setting and fraction collection. The separation results showed that six fractions (S1-S6) of different chemical components from 100 g Schisandra chinensis (Turcz) Baill. petroleum ether phase were obtained by the AUTO-VLC with 150 mm diameter dynamic axis compress chromatographic column. A new method used for the VLC separation parameters screened by using multiple development TLC was developed and confirmed. The initial mobile phase of AUTO-VLC was selected by taking Rf of all the target compounds ranging from 0 to 0.45 for fist development on the TLC; gradient elution ratio was selected according to k value (the slope of the linear function of Rf value and development times on the TLC) and the resolution of target compounds; elution times (n) were calculated by the formula n ≈ ΔRf/k. A total of four compounds with the purity more than 85% and 13 other components were separated from S5 under the selected conditions for only 17 h. Therefore, the development of the automatic VLC and its method are significant to the automatic and systematic separation of traditional Chinese medicines. PMID:26749864

  7. Gas chromatograph-based system for measuring the methane fraction of diesel-engine hydrocarbon emissions

    SciTech Connect

    Hoffman, J.S.; Geyer, S.M.; Lestz, S.S.; Black, F.M.

    1987-03-01

    An instrument has been developed (termed the methane analytical system) enabling diesel methane emissions to be quatified separately from total unburned hydrocarbon emissions. The instrument employed gas-chromatographic principles whereby a molecular-sieve column operating isothermally separated methane from the nonmethane hydrocarbons. Direct on-line sampling occurred via constant-volume sample loops. The effluent was monitored with a flame ionization detector. The instrument was fully calibrated (i.e., extremely linear response over a large concentration range) for use with diesel engines as part of an on-going alternative-fuels research program. Methane emissions from a light-duty, multi-cylinder, indirect-injected diesel engine fumigated with natural gas were measured on-line using the methane analytical system. Methane emissions were found to range from as low as 250 ppm to a high of nearly 2%. The nonmethane hydrocarbon emissions were determined by subtracting the methane level from the total unburned hydrocarbon level. In the event that the federal engine certification procedures are changed to be based on nonmethane hydrocarbon emissions, a methane analytical system such as the one described here would have great utility.

  8. Anaerobic digestion of the liquid fraction of dairy manure

    SciTech Connect

    Haugen, V.; Dahlberg, S.; Lindley, J.A.

    1983-06-01

    The authors tested several solid liquid separation systems suitable for processing dairy manure prior to anaerobic digestion. None of the systems tried have completely satisfied the requirements. Evaluated effects of separation on biogas production. Unseparated dairy manure produced more biogas than the liquid fraction.

  9. Systematic Robustness Testing of a Liquid Chromatographic Method: A Case Study.

    PubMed

    Mannemala, Sai Sandeep; Kannappan, Valliappan

    2015-01-01

    Robustness testing of a method plays a crucial role in establishing its reliability. It examines the potential sources of variability in one or more responses of the proposed method. In this study, the robustness testing of a method proposed for simultaneous determination of warfarin and its two process related impurities was evaluated by using two level, fractional factorial design. Factors that are sensitive to a variation during method transfer were selected as independent variables [aqueous content (range: 39-43%, v/v), concentration of acetic acid (range: 0.08-0.12%, v/v), flow rate (range: 0.93-1.33 mL/min), and wavelength (range: 218-222 nm)]. Variables that determine the quality of separation, viz., retention factor of the first peak, resolution between the critical peak pair, tailing factor of warfarin, and total analysis time were selected as responses. Robustness was assessed by graphical (half normal probability and Pareto plots) and statistical (analysis of variance) methods. It was found that, among the studied variables, aqueous content had a significant effect on capacity factor and analysis time. Furthermore, non-significant intervals for significant factors were established by contour profiling. This study demonstrated the significance of experimental design and other statistical tools in understanding the effects of investigating factors of the chromatographic system and in defining their limits. PMID:26651591

  10. Spectrophotometric and liquid chromatographic determination of trimebutine maleate in the presence of its degradation products.

    PubMed

    El-Gindy, Alaa; Emara, Samy; Hadad, Ghada M

    2003-09-19

    Three methods are presented for the determination of trimebutine maleate (TM) in the presence of its degradation products. The first method was based on a high performance liquid chromatographic (HPLC) separation of TM from its degradation products using an ODS column at ambient temperature with a mobile phase consisting of acetonitrile-5 mM heptane sulfonic acid disodium salt (45:55, v/v, pH 4) with UV detection at 215 nm. The second method depends on using first derivative spectrophotometry (1D) by measurement of the amplitude at 252.2 nm. The third method depends on using first derivative of the ratio spectrophotometry (1DD) by measurement of the amplitude at 282.4 nm where a normalized spectrum of 3,4,5-trimethoxy benzoic acid is used as divisor. The proposed HPLC and 1D methods were used to investigate the kinetics of acidic and alkaline degradation processes. The pH-rate profile of degradation of TM in Britton-Robinson buffer solutions within the pH range 2-11.9 was studied. PMID:12972088

  11. Liquid chromatographic determination of para-substituted N,N-dialkylaniline N-oxides.

    PubMed

    Seto, Y; Guengerich, F P

    1993-09-01

    A high-performance liquid chromatographic method for the determination of p-substituted N,N-dialkylaniline N-oxides [N,N-dimethylaniline N-oxide (DMANO), N,N-dimethyl-p-toluidine N-oxide, N,N-diethylaniline N-oxide, N-ethyl-N-methylaniline N-oxide (EMANO), p-cyano-N,N-dimethylaniline N-oxide (pCNDMANO), and N-phenylpyrrolidine N-oxide (PPNO)] has been developed. It uses an octadecylsilica column, a mobile phase of methanol-phosphate buffer (pH 7.0, adjusted by triethylamine) and ultraviolet detection. N-Oxides were eluted in the order of hydrophilicity except for PPNO, which eluted between DMANO and EMANO. The number of theoretical plates and the detection limit under optimized conditions were between 2400 (DMANO) and 5400 (pCNDMANO) and between 2.3 microM (pCNDMANO) and 30 microM (PPNO), respectively. The concentration of N-oxides recovered from enzyme reaction mixtures by solid-phase extraction using Sep-Pak C18 (prior to chromatography) was also optimized with regard to the sensitivity and interference. PMID:8245165

  12. Liquid chromatographic determination of folate monoglutamates in fish, meat, egg, and dairy products consumed in Finland.

    PubMed

    Vahteristo, L T; Ollilainen, V; Varo, P

    1997-01-01

    A liquid chromatographic (LC) method with fluorescence and UV detection was used to determine the folate contents of fish, meat, fish and meat products, chicken, eggs, and milk consumed in Finland. 5-Methyltetrahydrofolate, tetrahydrofolate, 5-formyltetrahydrofolate, 10-formylfolic acid, and folic acid from 24 commodities obtained from supermarkets, retail stores, and different outlets in the Helsinki area were analyzed. Pooled samples were extracted at pH 6.0 in the presence of antioxidants and deconjugated with hog kidney deconjugase. Very low levels of folates were detected in meat and meat products. Fresh fish, fish sticks, and chicken meat contained reasonable amounts (3-13 micrograms/100 g) of tetrahydrofolate and 5-methyltetrahydrofolate. Egg yolk contained high concentrations of 5-methyltetrahydrofolate (140-150 micrograms/100 g); 10-formylfolic acid was also detected (14-17 micrograms/100 g). Between-species differences in folate monoglutamate distributions were observed. The highest levels of tetrahydrofolate, > 5 micrograms/100 g, were found in chicken meat and fillets of rainbow trout, whitefish, and baltic herring. Tetrahydrofolate was most abundant in fresh fish. LC was well suited for analyzing folate compositions of meat, fish, and other foods of animal origin. Recovery of added folates ranged from 49 to 96%. PMID:9086593

  13. Group-type hydrocarbon standards for high-performance liquid chromatographic analysis of middistillate fuels

    NASA Technical Reports Server (NTRS)

    Otterson, D. A.; Seng, G. T.

    1984-01-01

    A new high-performance liquid chromatographic (HPLC) method for group-type analysis of middistillate fuels is described. It uses a refractive index detector and standards that are prepared by reacting a portion of the fuel sample with sulfuric acid. A complete analysis of a middistillate fuel for saturates and aromatics (including the preparation of the standard) requires about 15 min if standards for several fuels are prepared simultaneously. From model fuel studies, the method was found to be accurate to within 0.4 vol% saturates or aromatics, and provides a precision of + or - 0.4 vol%. Olefin determinations require an additional 15 min of analysis time. However, this determination is needed only for those fuels displaying a significant olefin response at 200 nm (obtained routinely during the saturated/aromatics analysis procedure). The olefin determination uses the responses of the olefins and the corresponding saturates, as well as the average value of their refractive index sensitivity ratios (1.1). Studied indicated that, although the relative error in the olefins result could reach 10 percent by using this average sensitivity ratio, it was 5 percent for the fuels used in this study. Olefin concentrations as low as 0.1 vol% have been determined using this method.

  14. Liquid chromatographic determination of safrole in sassafras-derived herbal products.

    PubMed

    Carlson, M; Thompson, R D

    1997-01-01

    A liquid chromatographic (LC) method was developed for determining safrole in herbal products derived from sassafras (Sassafras albidum), as well as related compounds such as isosafrole and dihydrosafrole. The procedure involves solvent extraction and isolation of analyte by reversed-phase LC with UV detection at 235 nm. Safrole is resolved from related compounds and other sample constituents including thymol, a component of thyme. A linear concentration range of 0.003-0.200 mg/mL was obtained for safrole, isosafrole, and dihydrosafrole. Limits of detection (LOD) and quantitation (LOQ) were e0.0015 and 0.0051 micrograms/mL for safrole, 0.0018 and 0.0061 micrograms/mL for isosafrole, and 0.0038 and 0.0125 micrograms/mL for dihydrosafrole, respectively. Intraday relative standard deviations (RSDs) for safrole (n = 5) from various samples ranged from 1.30 to 5.39% at analyte levels of 0.01-1.5%. Safrole contents of 26 samples including root bark powder, leaves, oils, tea concentrate, herbal extract tinctures, and herbal powder capsules ranged from < LOD for most leaf samples to 92.4% for an oil. Recoveries of safrole from fortified samples ranged from 83.6% for an oil to 117.2% for a tincture preparation. Safrole contents of 0.09-4.66 mg/cup were found for brewed teas prepared from sassafras root bark powders and tinctures. PMID:9325580

  15. Selective and sensitive liquid chromatographic determination method of 5-hydroxyindoles with fluorous and fluorogenic derivatization.

    PubMed

    Sakaguchi, Yohei; Ikenaga, Jun; Yoshida, Hideyuki; Hayama, Tadashi; Itoyama, Miki; Todoroki, Kenichiro; Imakyure, Osamu; Yamaguchi, Masatoshi; Nohta, Hitoshi

    2015-10-10

    A liquid chromatographic (LC) method with improved selectivity for the simultaneous determination of 5-hydroxyindoles (5-HIs; 5-hydroxytryptophan, 5-hydroxytryptamine, N-acetyl-5-hydroxytryptamine, 5-hydroxyindole-3-acetic acid, and 5-hydroxytryptophol) is described. This method involves precolumn derivatization with 4-(3',3',4',4',5',5',6',6',7',7',8',8',9',9',10',10',10'-heptadecafluorodecyl)benzylamine (HFBA) and separation of the derivatives using a fluorous LC column. In this study, stable benzoxazole derivatives of 5-HIs with HFBA have been obtained by a simple derivatization procedure; their fluorescent properties enabled highly sensitive detection. In addition, only the HFBA derivatives of 5-HIs has been selectively retained on the fluorous LC column via fluorous interaction whereby perfluoroalkyl compounds show affinities with each other, while the non-fluorous compounds did not. The HFBA derivatives were separated within 30 min and the detection limits for 5-HIs in a 20-μL injection volume were 1.2-14 fmol (S/N=3). Furthermore, this method was applied to the analysis of 5-HIs in the human plasma from healthy subjects. PMID:26112924

  16. High-performance liquid chromatographic-fluorescence determination of traces of selenium in biological materials.

    PubMed

    Hawkes, W C; Kutnink, M A

    1996-10-15

    An improved method for the determination of selenium in biological materials has been developed. This work both extends and validates the procedure of Vézina and Bleau (J. Chromatog. 426, 385-391, 1988) which is based on high-performance liquid chromatographic determination of the fluorophore formed by reaction of Se(IV) with 2,3-diaminonaphthalene. The mass detection limit is 48 pg selenium (3 sigma) and the concentration detection limits are 48 parts per trillion in biological fluids and 120 to 480 parts per trillion in dried biological materials. The linear dynamic range of the method has been extended up to approximately 800 ng. Relative standard deviations of 9.4 to 2.7% were observed in repeated analyses of standards in the range of 0.5 to 500 ng. The proposed method was validated with respect to 23 biological reference materials spanning an 1800-fold range of selenium concentrations and was found to be free of significant constant or proportional biases despite greatly different matrix compositions. This method offers an unsurpassed combination of sensitivity, accuracy, linear dynamic range, and freedom from matrix interferences and may be considered a reference method for the reliable determination of selenium in biological materials. PMID:8921189

  17. Liquid chromatographic determination of oxytetracycline in edible fish fillets from six species of fish

    USGS Publications Warehouse

    Meinertz, J.R.; Stehly, G.R.; Gingerich, W.H.

    1998-01-01

    The approved use of oxytetracycline (OTC) in U.S. Aquaculture is limited to specific diseases in salmonids and channel catfish. OTC may also be effective in controlling diseases in other fish species important to public aquaculture, but before approved use of OTC can be augmented, an analytical method for determining OTC in fillet tissue from multiple species of fish will be required to support residue depletion studies. The objective of this study was to develop and validate a liquid chromatographic (LC) method that is accurate, precise, and sensitive for OTC in edible fillets from multiple species of fish. Homogenized fillet tissues from walleye, Atlantic salmon, striped bass, white sturgeon, rainbow trout, and channel catfish were fortified with OTC at nominal concentrations of 10, 20, 100, 1000, and 5000 ng/g. In tissues fortified with OTC at 100, 1000, and 5000 ng/g, mean recoveries ranged from 83 to 90%, and relative standard deviations (RSDs) ranged from 0.9 to 5.8%. In all other tissues, mean recoveries ranged from 59 to 98%, and RSDs ranged from 3.3 to 20%. Method quantitation limits ranged from 6 to 22 ng/g for the 6 species. The LC parameters produced easily integratable OTC peaks without coelution of endogenous compounds. The method is accurate, precise, and sensitive for OTC in fillet tissue from 6 species of fish from 5 phylogenetically diverse groups.

  18. High-performance liquid chromatographic determination of triclosan and triclocarban in cosmetic products.

    PubMed

    Liu, T; Wu, D

    2012-10-01

    A high-performance liquid chromatographic (HPLC) method for the determination of triclosan and triclocarban in cosmetic products was developed. Triclosan and triclocarban quantities in 168 of cosmetics were investigated and statistical analyzed with this method. The optimal condition are as follows: An Agilent SB-C8 analytical column (250 × 4.6 mm, 5μm) was utilized, and mixed buffer solution of methanol and 0.01 mol L(-1) phosphate (pH 3.0) (72 : 28, V/V) were used for isocratic elution at a total flow rate of 1.0 mL min(-1) . It is found the calibration curves had a good linear regression with UV detection (280 nm) within test range of 0-110 μg mL(-1) with the correlation coefficients of 0.999 in all cases. This method is simple, selective, convenient, and reproducible for the determination of triclosan and triclocarban in commercial cosmetic products. PMID:22809056

  19. High-pressure liquid chromatographic analysis of aztreonam in sera and urine.

    PubMed Central

    Pilkiewicz, F G; Remsburg, B J; Fisher, S M; Sykes, R B

    1983-01-01

    Aztreonam (SQ 26,776) is a new synthetic monocyclic beta-lactam antibiotic which is specifically active against aerobic gram-negative bacteria. High-pressure liquid chromatographic (HPLC) systems were developed for the quantitative analysis of aztreonam in human, monkey, rat, mouse, and rabbit sera and urine. The HPLC conditions employed for these analyses were a muBondapak C18 column, a mobile phase made up of 0.005 M tetrabutylammonium hydrogen sulfate at pH 3.0 and acetonitrile or methanol, UV detection at 293 nm, and a flow rate of 2.0 ml/min. For human sera and urine, the mobile phase was 80% 0.005 M tetrabutylammonium hydrogen sulfate-0.005M (NH4)2SO4 and 20% acetonitrile (vol/vol). For the range of sera and urine, HPLC analyses were shown to have excellent detector linearity of aztreonam over a concentration range of 1.0 mg/ml to 0.5 microgram/ml. Correlation coefficients for plots of aztreonam peak area versus its concentration were greater than or equal to 0.990. The detection limit of aztreonam was 1.0 micrograms/ml in sera and 5.0 micrograms/ml in urine. HPLC and microbiological assays of aztreonam in human sera and urine were in good agreement. PMID:6684412

  20. Rapid liquid chromatographic determination of dimetridazole and ipronidazole in swine feed.

    PubMed

    Roybal, J E; Munns, R K; Hurlbut, J A; Shimoda, W; Morrison, T R; Vieira, C L

    1987-01-01

    A simple and rapid method is described for the determination of dimetridazole (DMZ) and ipronidazole (IPR) in swine feeds at various levels (0.11-110 ppm). The drugs are released from feed by prewetting with a buffer, followed by extraction with either methanol or methylene chloride, depending on the drug level; if necessary, an acid-base cleanup is used before the liquid chromatographic analysis. The analytes are separated on a C18 column and monitored at 320 nm for detection and quantitation. Recoveries of DMZ from several feed formulations averaged 108% at the 92.8 ppm level with a standard deviation (SD) of 4.00% and a coefficient of variation (CV) of 3.70%, 101% at the 11.2 ppm level with an SD of 11.9% and a CV of 11.8%, and 100% at the 0.112 ppm level with an SD of 9.27% and a CV of 9.25%. Recoveries of IPR averaged 77.1% at the 12.9 ppm level with an SD of 1.75% and a CV of 2.27%; IPR recoveries averaged 35.2% at the 0.129 ppm level with an SD of 3.39% and a CV of 9.63%. PMID:3624165

  1. The gas-liquid chromatograph and the electron capture detection in equine drug testing.

    PubMed Central

    Blake, J. W.; Tobin, T.

    1976-01-01

    Three gas-liquid chromatographic (G.L.C.) procedures discussed have been designed around the four "esses" of detection tests--speed, sensitivity, simplicity, and specificity. These techniques are admirably applicable to the very low plasma drug levels encountered in blood testing under pre-race conditions. The methods are equally applicable to post-race testing procedures, where both blood and urine samples are tested. Drugs can only rarely be detected by the electron capture detector (E.C.D.) without a prior derivatization step, which conveys to the drug(s) high electron affinity. Because of broad applicability, two derivatizing agents, heptafluorobutyric (HFBA) and pentafluorpropionic (PFPA) anhydrides are employed. The three techniques, allowing broad coverage of various drug classes are: 1) direct derivatization of drugs to form strongly electron capturing amides and esters. 2) reductive fragmentation of drugs with lithium aluminum hydride to form alcohols, with conversion to ester derivatives. 3) oxidative fragmentation of drugs with potassium dichromate to form derivatizable groups, followed by direct derivatization. PMID:1000157

  2. Liquid chromatographic method for determining the concentration of bisazir in water

    USGS Publications Warehouse

    Scholefield, Ronald J.; Slaght, Karen S.; Allen, John L.

    1997-01-01

    Barrier dams, traps, and lampricides are the techniques currently used by the Great Lakes Fishery Commission to control sea lampreys (Petromyzon marinus) in the Great Lakes. To augment these control techniques, a sterile-male-release research program was initiated at the Lake Huron Biological Station. Male sea lampreys were sterilized by intraperitoneal injection of the chemical sterilant P,P-bis(1-aziridinyl)-N-methylphosphinothioic amide (bisazir). An analytical method was needed to quantitate the concentration of bisazir in water and to routinely verify that bisazir (>25 μg/L) does not persist in the treated effluent discharged from the sterilization facility to Lake Huron. A rapid, accurate, and sensitive liquid chromatographic (LC) method was developed for determining bisazir in water. Bisazir was dissolved in Lake Huron water; extracted and concentrated on a C18 solid-phase extraction column; eluted with methanol; and quantitated by reversed-phase LC using a C18 column, a mobile phase of 70% water and 30% methanol (v/v), and UV detection (205 nm). Bisazir retention time was 7-8 min; total run time was about 20 min. Method detection limit for bisazir dissolved in Lake Huron water was about 15 μg/L. Recovery from Lake Huron water fortified with bisazir at 100 μg/L was 94% (95% confidence interval, 90.2-98.2%).

  3. Method modification for liquid chromatographic determination of thiamine, riboflavin, and pyridoxine in medical foods.

    PubMed

    Chase, G W; Landen, W O; Soliman, A G; Eitenmiller, R R

    1993-01-01

    A reversed-phased ion pair liquid chromatographic method developed for the simultaneous determination of thiamine (B1), riboflavin (B2), and pyridoxine (B6) in perchloric acid extracts of infant formulas was modified to include medical foods. UV detection of B1 and B2 was replaced by fluorescence detection, which resulted in improved sensitivity and specificity. B1 was detected by fluorescence after conversion to thiochrome by a postcolumn reaction with sodium hydroxide and potassium ferricyanide. The method uses a mobile phase of water, acetonitrile, hexanesulfonic acid sodium salt, ammonium hydroxide, and phosphoric acid adjusted to pH 3.6. The column is a 300 x 3.9 mm Nova Pak C18. Limits of detection were 0.05 microgram/mL for B1 and B2 and 0.01 microgram/mL for B6 by fluorescence detection. The system reproducibility was evaluated by completing 10 repetitive determinations on a medical food that gave a coefficient of variation of 5.9, 6.0, and 10.7% for B1, B2, and B6, respectively. Mean recoveries (n = 10) were 111, 96.3, and 113% for B1, B2, and B6, respectively. The results compared favorably with those by AOAC Official Methods 942.23, 940.33, and 961.15 for B1, B2, and B6, respectively. PMID:8286968

  4. Development and Validation of Liquid Chromatographic Method for Estimation of Naringin in Nanoformulation

    PubMed Central

    Musmade, Kranti P.; Trilok, M.; Dengale, Swapnil J.; Bhat, Krishnamurthy; Reddy, M. S.; Musmade, Prashant B.; Udupa, N.

    2014-01-01

    A simple, precise, accurate, rapid, and sensitive reverse phase high performance liquid chromatography (RP-HPLC) method with UV detection has been developed and validated for quantification of naringin (NAR) in novel pharmaceutical formulation. NAR is a polyphenolic flavonoid present in most of the citrus plants having variety of pharmacological activities. Method optimization was carried out by considering the various parameters such as effect of pH and column. The analyte was separated by employing a C18 (250.0 × 4.6 mm, 5 μm) column at ambient temperature in isocratic conditions using phosphate buffer pH 3.5: acetonitrile (75 : 25% v/v) as mobile phase pumped at a flow rate of 1.0 mL/min. UV detection was carried out at 282 nm. The developed method was validated according to ICH guidelines Q2(R1). The method was found to be precise and accurate on statistical evaluation with a linearity range of 0.1 to 20.0 μg/mL for NAR. The intra- and interday precision studies showed good reproducibility with coefficients of variation (CV) less than 1.0%. The mean recovery of NAR was found to be 99.33 ± 0.16%. The proposed method was found to be highly accurate, sensitive, and robust. The proposed liquid chromatographic method was successfully employed for the routine analysis of said compound in developed novel nanopharmaceuticals. The presence of excipients did not show any interference on the determination of NAR, indicating method specificity. PMID:26556205

  5. Chromatogram Handler: A unique computer program that efficiently processes data generated in liquid chromatographic investigations of organic ligand adsorption on mineral surfaces

    NASA Astrophysics Data System (ADS)

    Kreller, David I.; Young, Stephen P.; Mendez, Eladio A.; McGunigale, Samantha L.

    2012-09-01

    We describe a unique C# computer program developed in our laboratory to efficiently manipulate data generated when a novel liquid chromatographic (LC) 'pulsed addition' technique is used to study organic ligand interactions with mineral surfaces. We are not aware of the existence of a program of this nature elsewhere. Geochemically-relevant ligands studied include dissolved organic matter (DOM) mixtures and single component low molecular weight organic acids. Although our LC system has three optical (absorbance and fluorescence) detection channels, the utility can process data from experiments in which data was collected in one, two or three detection channels. If not automated, data management and processing for the technique is prohibitively complex and time-consuming, due large data volumes and the number of operations involved. The input for the utility in a processing run is the set of detector output files generated during an LC experiment. During processing, the utility generates an MS Excel output file within which, for each detection channel: (i) chromatographic peak areas and peak retention times are determined, (ii) area-normalized per-injection and cumulative adsorption densities are calculated, and (iii) graphical representations of various quantities calculated from the raw data are automatically generated. When processing data from experiments with multiple detection channels, the utility additionally prepares graphs that compare recovery values calculated from data in different detection channels, and calculates (and plots) spectroscopic/chromatographic indices which are ratios of signals in various detection channels. The utility was programmed to perform these additional operations on data from multi-channel experiments because (i) 'Interchannel' comparisons of recovery provide insight into the differing surface behavior of distinct DOM sub-fractions, and (ii) the spectroscopic indices provide a useful new form of data that provides insight into

  6. Performance characteristics of bioassay, radioenzymatic assay, homogeneous enzyme immunoassay, and high-performance liquid chromatographic determination of serum gentamicin

    SciTech Connect

    Delaney, C.J.; Opheim, K.E.; Smith, A.L.; Plorde, J.J.

    1982-01-01

    We compared the accuracy, precision, and between-method error of the microbiological assay, the radioenzymatic assay, the homogeneous enzyme immunoassay, and the high-performance liquid chromatographic assay for the quantitation of gentamicin in serum. Precision and accuracy were evaluated by reference samples prepared to contain 0.0 to 32.7 micrograms of gentamicin per ml. Correlations between the methods utilized patient sera with gentamicin concentrations ranging from 0.6 to 13.3 micrograms/ml. All methods were reliable within acceptable limits for routine clinical use; intermethod correlation coefficients exceeded 0.96. Relative to the microbiological assay, the alternative methods offer the advantage of rapid analysis. The elapsed times for acquiring data on a set of 10 specimens under routine operating conditions were 0.5 h by the enzyme immunoassay, 4 h by the radioenzymatic assay, 5 h by the high-performance liquid chromatographic assay, and 10 h by the microbiological assay.

  7. Performance characteristics of bioassay, radioenzymatic assay, homogeneous enzyme immunoassay, and high-performance liquid chromatographic determination of serum gentamicin.

    PubMed Central

    Delaney, C J; Opheim, K E; Smith, A L; Plorde, J J

    1982-01-01

    We compared the accuracy, precision, and between-method error of the microbiological assay, the radioenzymatic assay, the homogeneous enzyme immunoassay, and the high-performance liquid chromatographic assay for the quantitation of gentamicin in serum. Precision and accuracy were evaluated by reference samples prepared to contain 0.0 to 32.7 micrograms of gentamicin per ml. Correlations between the methods utilized patient sera with gentamicin concentrations ranging from 0.6 to 13.3 micrograms/ml. All methods were reliable within acceptable limits for routine clinical use; intermethod correlation coefficients exceeded 0.96. Relative to the microbiological assay, the alternative methods offer the advantage of rapid analysis. The elapsed times for acquiring data on a set of 10 specimens under routine operating conditions were 0.5 h by the enzyme immunoassay, 4 h by the radioenzymatic assay, 5 h by the high-performance liquid chromatographic assay, and 10 h by the microbiological assay. PMID:7044297

  8. Liquid chromatographic determination of methylxanthines and catechins in herbal preparations containing guaraná.

    PubMed

    Carlson, M; Thompson, R D

    1998-01-01

    Herbal preparations derived from the dried seeds of guaraná (Paullinia cupana) have become a popular nutritional supplement used for stimulatory purposes. Once considered a drug substance in the United States, guaraná currently is classified as a food additive and dietary supplement. The pharmacological activity of guaraná-containing products is primarily due to methylxanthine alkaloids. For guaraná preparations, methylxanthine levels and, more significantly, the presence of several polyphenol compounds (i.e., catechins) provide phytochemical markers of authenticity. Methylxanthines and polyphenols are extracted from sample matrix with a heated phosphate buffer-methanol solution, the cooled extract is filtered, and the extract is injected into the liquid chromatographic (LC) system. A Nova-Pak C18 column eluted with phosphate buffer-methanol mobile phase (pH = 3.50) and monitored at 272 nm gave satisfactory resolution for the methylxanthines theobromine, theophylline, caffeine and the polyphenols (+)-catechin and (-)-epicatechin. Twenty-four products including dried seeds, dried paste, seed powders, tablets, and capsule formulations were assayed and conclusions were drawn about their authenticity. The LC system responded linearly to methylxanthines over the 100-fold range in concentration from 0.043 to 4.30 micrograms/mL for theobromine and caffeine and from 0.041 to 4.10 micrograms/mL for theophylline. Precision data for the 3 methylxanthines obtained from 10 different products (n = 5) gave relative standard deviation (RSD) values of 1.18-15.52% within a concentration range of 0.01-52.28 mg/g. Recoveries of methylxanthines from fortified products varied from 87.5 to 120.0%. The response for catechins was linear over a 200-fold range in concentration of 0.05-10.0 micrograms/mL. Precision data from 5 products (n = 5) gave RSD values of 1.08-5.54% within a concentration range of 0.34-32.65 mg/g. Recoveries from these products ranged from 87.7 to 109.7%. Results

  9. High performance liquid chromatographic method for the determination of cinepazide maleate and its application to a pharmacokinetic study in rats.

    PubMed

    Zhao, Jinyi; Song, Ying; Wang, Hujun; Sun, Yuan; Liu, Meiyou; Lu, Chengtao; Li, Yan; Wang, Shan; Zhu, Xiaohe; Hai, Wenli; Wen, Aidong; Jia, Yanyan

    2014-04-15

    A simple and reliable high performance liquid chromatographic (HPLC) method has been developed and validated to quantify cinepazide maleate, a calcium blocker, in rat plasma. Cinepazide maleate and Tinidazole (internal standard) have been extracted by a simple liquid-liquid extraction before injection into chromatographic system. Chromatographic separation was achieved on a reversed phase C18 column with a mobile phase consisted of a water mixture of 10mM potassium dihydrogen phosphate (pH=4.5):methanol (40:60, v/v), pumped at flow rate of 1.0mL/min, and detected at 303nm. The method exhibited a linear range of 0.12-120μg/mL in blank rat plasma, with the lower detection limit of 0.06μg/mL. The method was statistically validated for linearity, accuracy, precision, selectivity and stability following FDA guidelines. The intra- and inter-assay coefficients of variation did not exceed ±15% from the nominal concentration. The accuracy of cinepazide maleate was within ±15% of the theoretical value. The assay has been applied successfully in a pharmacokinetic study of cinepazide maleate after a single intravenous at three doses in rat. And cinepazide maleate injection can improve the bioavailability of cinepazide maleate greatly, and has a dose-dependence profile in rats. PMID:24674989

  10. LIQUID CHROMATOGRAPHIC SEPARATION OF THE ENANTIOMERS OF TRANS-CHLORDANE, CIS-CHLORDANE, HEPTACHLOR, HEPTACHLOR EPOXIDE AND ALPHA-HEXACHLOROCYCLOHEXANE WITH APPLICATION TO SMALL-SCALE PREPARATIVE SEPARATION

    EPA Science Inventory

    Analytical high-performance liquid chromatographic separations of the individual enantiomers of five polychlorinated compounds were obtained on polysaccharide stereoselective HPLC columns. The enantiomers of the pesticides trans-chlordane, cis-chlordane and heptachlor were separa...

  11. Solvated liquid-lignin fractions from a Kraft black liquor.

    PubMed

    Velez, Julian; Thies, Mark C

    2013-11-01

    A softwood Kraft black liquor was acidified with carbon dioxide at 115°C and 6.2 bar over a pH range of 13.6-9.5, resulting in the precipitation of liquefied-lignin fractions as a separate phase. Seven such "liquid-lignin" fractions were produced, with each fraction being phase-separated within a narrow pH band of 0.5 units. The fractions were found to be highly hydrated phases, containing 32.3-48.2 wt.% water; as a result, their measured melting points were quite low, 90.7-110.5°C. In contrast, no melting point was detected up to 375°C for any of the lignin fractions after drying. Significant reductions in metals content were observed for the lignin fractions compared to the original black-liquor feed. PMID:24054066

  12. Retention projection enables accurate calculation of liquid chromatographic retention times across labs and methods.

    PubMed

    Abate-Pella, Daniel; Freund, Dana M; Ma, Yan; Simón-Manso, Yamil; Hollender, Juliane; Broeckling, Corey D; Huhman, David V; Krokhin, Oleg V; Stoll, Dwight R; Hegeman, Adrian D; Kind, Tobias; Fiehn, Oliver; Schymanski, Emma L; Prenni, Jessica E; Sumner, Lloyd W; Boswell, Paul G

    2015-09-18

    Identification of small molecules by liquid chromatography-mass spectrometry (LC-MS) can be greatly improved if the chromatographic retention information is used along with mass spectral information to narrow down the lists of candidates. Linear retention indexing remains the standard for sharing retention data across labs, but it is unreliable because it cannot properly account for differences in the experimental conditions used by various labs, even when the differences are relatively small and unintentional. On the other hand, an approach called "retention projection" properly accounts for many intentional differences in experimental conditions, and when combined with a "back-calculation" methodology described recently, it also accounts for unintentional differences. In this study, the accuracy of this methodology is compared with linear retention indexing across eight different labs. When each lab ran a test mixture under a range of multi-segment gradients and flow rates they selected independently, retention projections averaged 22-fold more accurate for uncharged compounds because they properly accounted for these intentional differences, which were more pronounced in steep gradients. When each lab ran the test mixture under nominally the same conditions, which is the ideal situation to reproduce linear retention indices, retention projections still averaged 2-fold more accurate because they properly accounted for many unintentional differences between the LC systems. To the best of our knowledge, this is the most successful study to date aiming to calculate (or even just to reproduce) LC gradient retention across labs, and it is the only study in which retention was reliably calculated under various multi-segment gradients and flow rates chosen independently by labs. PMID:26292625

  13. High-performance liquid chromatographic determination of memantine hydrochloride in rat plasma using sensitive fluorometric derivatization.

    PubMed

    Xie, Mei-Fen; Zhou, Wei; Tong, Xin-Yi; Chen, Yi-Le; Cai, Yi; Li, Yan; Duan, Geng-Li

    2011-02-01

    In this study, we investigated a simple, sensitive and reliable liquid chromatography-fluorescence detection method for the determination of memantine hydrochloride in rat plasma which was based on derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl). For the first time, FMOC-Cl was introduced into derivatization of memantine hydrochloride in rat plasma. The amino groups of memantine hydrochloride and amantadine hydrochloride (internal standard) were trapped with FMOC-Cl to form memantine hydrochloride-FMOC-Cl and amantadine hydrochloride-FMOC-Cl compositions, which can be very compatible for LC-FLD. Precipitation of plasma proteins by acetonitrile was followed by vortex mixing and centrifugation. Chromatographic separation was performed on a C(18) column (DIAMONSIL 150 × 4.6 mm, id 5 μm) with a mobile phase consisting of acetonitrile and water at a flow rate of 1.0 mL/min. The retention times of memantine hydrochloride-FMOC-Cl and amantadine hydrochloride-FMOC-Cl compositions were 23.69 and 40.27 min, respectively. Optimal conditions for the derivatization of memantine hydrochloride were also described. The limit of quantification (LOQ) was 25 ng/mL for memantine hydrochloride in plasma, the linear range was 0.025-5.0 μg/mL in plasma with a correlation coefficient (r) of 0.9999. The relative standard deviations (RSDs) of intra-day and inter-day assays were 4.46-12.19 and 5.23-11.50%, respectively. The validated method was successfully applied to the determination of memantine hydrochloride in rat plasma samples. PMID:21268245

  14. Pharmacokinetics of mitomycin C in dogs: application of a high-performance liquid chromatographic assay.

    PubMed

    Barbhaiya, R H; Papp, E A; Van Harken, D R; Smyth, R D

    1984-09-01

    A normal-phase high-performance liquid chromatographic (HPLC) assay was developed for the determination of mitomycin C in plasma and urine. The method involves extraction of mitomycin C from plasma or urine into ethyl acetate-2-propanol-chloroform (70:15:15) with UV detection at 365 nm. Quantitation was performed with an internal standard (porfiromycin) by the peak height ratio method. Excellent correlation was obtained between the HPLC assay and the established microbiological cup-plate bioassay. The pharmacokinetics of mitomycin C were investigated in beagle dogs following a 1-mg/kg iv (22-mg/m2) bolus dose. The plasma mitomycin C concentration versus time data were analyzed by using an open three-compartment model. The average volume of distribution was 1.90 L or 17% of body weight for the central compartment and 7.7 L or 68% of body weight for the terminal elimination phase. The volumes of distribution at steady state, calculated by model-dependent and -independent methods, compared very well with each other and were 6.5 L or 58% of body weight. Total body clearance averaged 112 mL/min, and the mean terminal plasma half-life was 53 min. The 0-24-h urinary excretion of intact mitomycin C accounted for 19% of the dose. The terminal half-life and percent urinary recovery of mitomycin C in dogs is similar to that in humans. Based on these observations, the dog appears to be a good model for studying the disposition of mitomycin C. PMID:6436466

  15. Determination of formate in natural waters by a coupled enzymatic/high-performance liquid chromatographic technique

    SciTech Connect

    Kieber, D.J.; Vaughan, G.M.; Mopper, K.

    1988-09-01

    An enzymatic method was developed to quantify formic acid in natural water samples at submicromolar concentrations. The method is based on the oxidation of formate by formate dehydrogenase with corresponding reduction of ..beta..-nicotinamide adenine dinucleotide (..beta..-NAD/sup +/) to reduced ..beta..-NAD/sup +/ (..beta..-NADH); ..beta..-NADH is quantified by reversed-phase high-performance liquid chromatography with fluorometric detection. An important feature of this method is that the enzymatic reaction occurs directly in aqueous media, even sea water, and does not require sample pretreatment other than sample filtration. The reaction proceeds at room temperature at a slightly alkaline pH (7.5 - 8.5) and is specific for formate with a detection limit of 0.5 ..mu..M (S/N = 4) for a 200-..mu..L injection. The precision of the method was 4.6% relative standard deviation (n = 6) for a 0.6 ..mu..M standard addition of formate to Sargasso sea water. Average recoveries of 2 ..mu..M additions of formate to sea water, pore water, or rain were 103, 103, and 87%, respectively. Intercalibration with a Dionex ion chromatographic system showed an excellent agreement of 98%. Concentrations of formate present in natural samples ranged from 0.2 to 0.8 ..mu..M for Biscayne Bay sea water, 0.4 to 10.0 ..mu..M for Miami rain, and 0.9 to 8.4 ..mu..M for Biscayne Bay sediment pore water.

  16. Liquid chromatographic determination of para-toluenesulfonamide in edible fillet tissues from three species of fish

    USGS Publications Warehouse

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

    1999-01-01

    Chloramine-T (N-sodium-N-chloro-p-toluene-sulfonamide) is a candidate therapeutic drug for treating bacterial gill disease, a predominant disease of a variety of fish species. Research has been initiated to obtain the U.S. Food and Drug Administration's (FDA) approval for the use of chloramine-T on a variety of fish species. An attribute of a therapeutic aquaculture drug that must be characterized before the FDA approves its use is depletion of the drug's marker residue (the drug's parent compound or metabolite of highest concentration in an edible tissue). Para-Toluenesulfonamide (p-TSA) is the primary degradation product and marker residue for chloramine-T in rainbow trout. To conduct residue depletion studies for chloramine-T in fish, a robust analytical method sensitive and specific for p-TSA residues in edible fillet tissue from a variety of fish was required. Homogenized fillet tissues from rainbow trout (Oncorhynchus mykiss), walleye (Stizostedion vitreum), and channel catfish (Ictalurus punctatus) were fortified at nominal p-TSA concentrations of 17, 67, 200, 333, and 1000 ng/g. Samples were analyzed by isocratic reversed-phase liquid chromatography (LC) with absorbance detection at 226 nm. Mean recoveries of p-TSA ranged from 77 to 93.17%; relative standard deviations ranged from 1.5 to 14%; method quantitation limits ranged from 13 to 18 ng/g; and method detection limits ranged from 3.8 to 5.2 ng/g. The LC parameters produced p-TSA peaks without coelution of endogenous compounds and excluded chromatographic interference from at least 20 chemicals and drugs of potential use in aquaculture.

  17. Liquid chromatographic-electrochemical determination of ethylenethiourea in foods by revised official method.

    PubMed

    Krause, R T

    1989-01-01

    AOAC official method 29.119-29.125 was revised to determine ethylenethiourea (ETU) directly by a liquid chromatographic-electrochemical (LC-EC) determinative technique and to improve ETU recovery. ETU is extracted from food products with a methanol-aqueous sodium acetate solution. A portion of the concentrated filtrate is added to a column of diatomaceous earth, and ETU is eluted with 2% methanol in methylene chloride to separate it from food coextractives, which are retained on the column. The eluate is collected in a siliconized flask and evaporated, the residue is dissolved in water, and 20 microL of solution is injected onto an LC graphitized carbon column. ETU is eluted from the LC column with a mobile phase of acetonitrile-aqueous 0.1M phosphoric acid-water (5 + 25 + 70), and the eluted ETU is detected by using an amperometric electrochemical detector equipped with a gold/mercury working electrode. Recovery data were obtained by fortifying 13 food products with ETU: baked potatoes; canned applesauce, mushrooms, creamed spinach, green beans, spinach, and tomatoes; cooked fresh cabbage and frozen collards; fresh celery and lettuce; grape jelly; and powdered sugar cake donuts. Raw celery was found to cause low ETU recoveries. Average percent recoveries of ETU from the other 12 food products were 92 with a standard deviation of 12 for the low (0.05 and 0.1 ppm) fortification levels and 90 with a standard deviation of 6 for the higher (0.5 and 1 ppm) fortification levels. The limits of quantitation were 0.01 and 0.02 ppm for food products with low and high sugar content, respectively. PMID:2592320

  18. Computer assisted optimization of liquid chromatographic separations of small molecules using mixed-mode stationary phases.

    PubMed

    Ordoñez, Edgar Y; Benito Quintana, José; Rodil, Rosario; Cela, Rafael

    2012-05-18

    Mixed-mode stationary phases are gaining adepts in liquid chromatography (LC) as more and more applications are published and new commercial columns appear in the market ought to their ability to retain and separate analytes with multiple functionalities. The increased number of adjustable variables gives these columns an enhanced value for the chromatographer, but, on the other hand, it complicates the process of developing satisfactory separations when complex samples must be analyzed. Thus, the availability of computer assisted methods development (CAMD) tools is highly desirable in this field. Therefore, the first specific tool for the CAMD of LC separations in mixed-mode columns is presented. The tool consists in two processes. The first one develops a retention model for peaks in a predefined experimental domain of pH and buffer concentration. In this domain, the retention as a function of the proportion of organic modifier is modeled using a two-stage re-calibration process departing from isocratic retention data and then, from gradient elutions. With this two-stage approach, reliability is gained. In the second process, the model is finally interpolated and used for the unattended optimization of the different possible elution modes available in these columns. This optimization process is driven by an evolutionary algorithm. The development and application of this new chemometrics tool is demonstrated by the optimization of a mixture of neutral and ionizable compounds. Hence, several different types of gradients were generated, showing a good agreement between simulated and experimental data, with retention time errors lower than 5% in most cases. On the other hand, classical CAMD tools, such as design of experiments, were unable to efficiently deal with mixed-mode optimizations, rendering errors above 30% for several compounds. PMID:22494641

  19. QbD-oriented development and validation of a bioanalytical method for nevirapine with enhanced liquid-liquid extraction and chromatographic separation.

    PubMed

    Beg, Sarwar; Chaudhary, Vandna; Sharma, Gajanand; Garg, Babita; Panda, Sagar Suman; Singh, Bhupinder

    2016-06-01

    The present studies describe the systematic quality by design (QbD)-oriented development and validation of a simple, rapid, sensitive and cost-effective reversed-phase HPLC bioanalytical method for nevirapine in rat plasma. Chromatographic separation was carried out on a C18 column using isocratic 68:9:23% v/v elution of methanol, acetonitrile and water (pH 3, adjusted by orthophosphoric acid) at a flow rate of 1.0 mL/min using UV detection at 230 nm. A Box-Behnken design was applied for chromatographic method optimization taking mobile phase ratio, pH and flow rate as the critical method parameters (CMPs) from screening studies. Peak area, retention time, theoretical plates and peak tailing were measured as the critical analytical attributes (CAAs). Further, the bioanalytical liquid-liquid extraction process was optimized using an optimal design by selecting extraction time, centrifugation speed and temperature as the CMPs for percentage recovery of nevirapine as the CAA. The search for an optimum chromatographic solution was conducted through numerical desirability function. Validation studies performed as per the US Food and Drug Administration requirements revealed results within the acceptance limit. In a nutshell, the studies successfully demonstrate the utility of analytical QbD approach for the rational development of a bioanalytical method with enhanced chromatographic separation and recovery of nevirapine in rat plasma. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26352459

  20. Liquid chromatographic determination of hydralazine in human plasma with 2-hydroxy-1-naphthaldehyde pre-column derivatization.

    PubMed

    Mañes, J; Mari, J; Garcia, R; Font, G

    1990-01-01

    A selective and sensitive high-performance liquid chromatographic method is described for determination of hydralazine and its metabolites in human plasma. The method involves pre-column derivatization with 2-hydroxy-1-naphthaldehyde at pH 1.2. The reaction product and Methyl Red used as internal standard are extracted into dichloromethane and chromatographed in the reversed-phase mode on an ODS-2 column using acetonitrile-aqueous triethylamine phosphate buffer (80:20, v/v) at pH 3 as eluent. The plasma calibration curve of hydralazine is linear in the concentration range 10-500 ng ml-1. The detection limit is 1 ng ml-1 and the relative standard deviation is less than 2.4. In vivo pharmacokinetics of hydralazine in two volunteers after oral administration of 50 mg of the drug is studied using the proposed LC method. PMID:2100625

  1. Quantitative liquid chromatographic determination of cefatrizine in serum and urine by fluorescence detection after post-column derivatization.

    PubMed

    Crombez, E; Van der Weken, G; Van den Bossche, W; De Moerloose, P

    1979-09-21

    A fast, specific and sensitive high-performance liquid chromatographic procedure for the determination of cefatrizine, an orally active cephalosporin, in serum and urine is proposed. The drug is determined by the internal standard method, using cephradine as the internal standard. The separation is carried out on a reversed-phase column, filled with octadecylsilane chemically bonded microparticles. The eluent is a mixture of acetonitrile with 0.025 M sodium phosphate buffer (pH 7). Quantitation is effected by fluorescence detection of the fluorophores formed after post-column derivatization with fluorescamine in a packed-bed reactor. The chromatographic conditions and the conditions for the post-column derivatization are discussed. The method has been applied to serum and urine samples, which were analysed after deproteinization with trichloroacetic acid and injection of the clear supernatant. The accuracy and reproducibility of the procedure were investigated by the determination of the cefatrizine content in spiked serum and urine samples. PMID:528641

  2. Storing of Extracts in Polypropylene Microcentrifuge Tubes Yields Contaminant Peak During Ultra-flow Liquid Chromatographic Analysis

    PubMed Central

    Kshirsagar, Parthraj R.; Hegde, Harsha; Pai, Sandeep R.

    2016-01-01

    Background and Aim: This study was designed to understand the effect of storage in polypropylene microcentrifuge tubes and glass vials during ultra-flow liquid chromatographic (UFLC) analysis. Materials and Methods: One ml of methanol was placed in polypropylene microcentrifuge tubes (PP material, Autoclavable) and glass vials (Borosilicate) separately for 1, 2, 4, 8, 10, 20, 40, and 80 days intervals stored at −4°C. Results: Contaminant peak was detected in methanol stored in polypropylene microcentrifuge tubes using UFLC analysis. The contaminant peak detected was prominent, sharp detectable at 9.176 ± 0.138 min on a Waters 250–4.6 mm, 4 μ, Nova-Pak C18 column with mobile phase consisting of methanol:water (70:30). Conclusion: It was evident from the study that long-term storage of biological samples prepared using methanol in polypropylene microcentrifuge tubes produce contaminant peak. Further, this may mislead in future reporting an unnatural compound by researchers. SUMMARY Long-term storage of biological samples prepared using methanol in polypropylene microcentrifuge tubes produce contaminant peakContamination peak with higher area under the curve (609993) was obtained in ultra-flow liquid chromatographic run for methanol stored in PP microcentrifuge tubesContamination peak was detected at retention time 9.113 min with a lambda max of 220.38 nm and 300 mAU intensity on the given chromatographic conditionsGlass vials serve better option over PP microcentrifuge tubes for storing biological samples. Abbreviations used: UFLC: Ultra Flow Liquid Chromatography; LC: Liquid Chromatography; MS: Mass spectrometry; AUC: Area Under Curve. PMID:27563216

  3. Column performance study of different variants of liquid chromatographic technique: an application on pharmaceutical ternary mixtures containing tetryzoline.

    PubMed

    Salem, Hesham; Hassan, Nagiba Y; Lotfy, Hayam M; Saleh, Sarah S

    2015-01-01

    High-performance liquid chromatography (HPLC), ultra-performance liquid chromatography (UPLC) and rapid resolution liquid chromatographic (RRLC) methods have been developed and validated for the separation and quantitation of both or either of two ternary mixtures present in ophthalmic solutions. The first mixture contains chloramphenicol, dexamethasone sodium phosphate and tetryzoline HCl (TZH); while the second one contains ofloxacin, prednisolone acetate and TZH. Both preparations contain benzalkonium chloride as a preservative. The columns used were a HPLC column (C18 5 µm particle size), a RRLC column (C18 2.6 µm particle size) and a UPLC column (C18 1.7 µm particle size). A comparative study was conducted to illustrate the effect of the change in column particle size and dimensions on the other chromatographic conditions, backpressure and the separation of both ternary mixtures. The methods were validated as per ICH guidelines where accuracy, repeatability, interday precision and robustness were found to be within the acceptable limits. The RRLC column provided shorter run time and better resolution than HPLC, while the UPLC column gave the shortest run time for all columns. The RRLC column resulted in minimum backpressure, so it could be used with any HPLC instrument, which makes the method more practical and economic. The results obtained from the proposed methods were statistically compared with official ones where no significant difference was observed. PMID:25217705

  4. Multiresidue chromatographic method for the determination of macrolide residues in muscle by high-performance liquid chromatography with UV detection.

    PubMed

    Juhel-Gaugain, M; Anger, B; Laurentie, M

    1999-01-01

    A high-performance liquid chromatographic (HPLC) method for the simultaneous determination of tilmicosin, tylosin, spiramycin, and its major metabolite neospiramycin was developed that is suitable for porcine, bovine, and poultry muscles. Macrolide residues were extracted from muscle with acetonitrile, fat was removed by liquid-liquid extraction with isooctane, and the extract was then cleaned on Bond Elut C18 cartridges. The HPLC separation was performed on an Inertsil ODS3 C18 column (150 x 4 mm) with 0.05% trifluoroacetic acid-acetonitrile in a gradient mode. Two different chromatographic gradients were used for tilmicosin-tylosin and spiramycin-neospiramycin, and the detection wavelengths were 287 and 232 nm, respectively. The method was validated from 1/2 the maximum residue limit (MRL) to 4 times the MRL with pork muscle samples. Mean recoveries were 60, 63.5, 51, and 42% for tilmicosin, tylosin, spiramycin, and neospiramycin, respectively. The detection limits are 15 micrograms/kg for tilmicosin and tylosin, 30 micrograms/kg for spiramycin, and 25 micrograms/kg for neospiramycin. Linearity, precision, and accuracy of the method were also tested. PMID:10513006

  5. A general static-headspace gas chromatographic method for determination of residual benzene in oral liquid pharmaceutical products.

    PubMed

    Liu, Hui; Tang, Qinglin; Markovich, Robert J; Rustum, Abu M

    2011-01-25

    Sodium benzoate is used in oral liquid pharmaceutical products for its anti-microbial properties. The benzoate salts present in liquid pharmaceutical products can potentially generate residual levels of free benzene during manufacturing of the drug product and or during the shelf-life of the product under its storage conditions. To ensure the safety and quality of the pharmaceutical products (containing benzoate in the formulation), a selective and sensitive analytical method is required to monitor residual benzene in oral liquid pharmaceutical products. In this paper, we report the development and validation of a general static-headspace gas chromatographic (SH-GC) method to determine residual benzene in oral liquid pharmaceutical products. The liquid pharmaceutical drug product sample is dissolved in dimethylsulfoxide (DMSO) in a GC headspace vial. A DB-624 capillary column (30 m x 0.32 mm I.D. and 1.8 μm film thickness) was used under isothermal conditions with a flame ionization detection (FID). The benzene peak was well separated from all other volatile compounds that are present in the formulation of a number of liquid drug products. This method was successfully validated using a representative oral liquid pharmaceutical drug product. The limit of detection of the method for benzene is 0.5 ppm which met the 2 ppm limit of current ICH guideline for residual benzene in pharmaceutical products. PMID:20926217

  6. High-performance liquid chromatographic determination of L-aspartyl-L-phenylalanine methyl ester in various food products and formulations.

    PubMed

    Fox, L; Anthony, G D; Lau, E P

    1976-09-01

    A simple, rapid, and specific high-performance liquid chromatographic (HPLC) procedure is described for the analysis of the chemical sweetener L-aspartyl-L-phenylalanine methyl ester (aspartame). Using a strong cation exchange column and pressures less than 1000 psig, an analysis can be performed in less than 15 min. The technique has been applied to a wide range of food products and formulations. No interferences were found in the samples studied. Recoveries are quantitative, and the coefficients of variation for replicate analyses are less than or equal to 2.5%. PMID:965327

  7. High performance liquid chromatographic separation of polycyclic aromatic hydrocarbons on microparticulate pyrrolidone and application to the analysis of shale oil

    SciTech Connect

    Mourey, T.H.; Siggia, S.; Uden, P.C.; Crowley, R.J.

    1980-05-01

    A chemically bonded pyrrolidone substrate is used for the high performance liquid chromatographic separation of polycyclic aromatic hydrocarbons. The cyclic amide phase interacts electronically with the polycyclic aromatic hydrocarbons in both the normal and reversed phase modes. Separation is effected according to the number of aromatic rings and the type of ring condensation. Information obtained is very different from that observed on hydrocarbon substrates, and thus these phases can be used in a complementary fashion to give a profile of polycyclic aromatics in shale oil samples. 7 figures, 1 table.

  8. Fractional Consumption of Liquid Hydrogen and Liquid Oxygen During the Space Shuttle Program

    NASA Technical Reports Server (NTRS)

    Partridge, Jonathan K.

    2011-01-01

    The Space Shuttle uses the propellants, liquid hydrogen and liquid oxygen, to meet part of the propulsion requirements from ground to orbit. The Kennedy Space Center procured over 25 million kilograms of liquid hydrogen and over 250 million kilograms of liquid oxygen during the 3D-year Space Shuttle Program. Because of the cryogenic nature of the propellants, approximately 55% of the total purchased liquid hydrogen and 30% of the total purchased liquid oxygen were used in the Space Shuttle Main Engines. The balance of the propellants were vaporized during operations for various purposes. This paper dissects the total consumption of liqUid hydrogen and liqUid oxygen and determines the fraction attributable to each of the various processing and launch operations that occurred during the entire Space Shuttle Program at the Kennedy Space Center.

  9. Fractional consumption of liquid hydrogen and liquid oxygen during the space shuttle program

    NASA Astrophysics Data System (ADS)

    Partridge, Jonathan K.

    2012-06-01

    The Space Shuttle uses the propellants, liquid hydrogen and liquid oxygen, to meet part of the propulsion requirements from ground to orbit. The Kennedy Space Center procured over 350 million liters of liquid hydrogen and over 200 million liters of liquid oxygen during the 30-year Space Shuttle Program. Because of the nature of the cryogenic propellants, approximately 54% of the total purchased liquid hydrogen and 32% of the total purchased liquid oxygen were used in the Space Shuttle Main Engines. The balance of the propellants were vaporized during operations for various purposes. This paper dissects the total consumption of liquid hydrogen and liquid oxygen and determines the fraction attributable to each of the various processing and launch operations that occurred during the entire Space Shuttle Program at the Kennedy Space Center.

  10. Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis

    PubMed Central

    Larsen, K.K.; Wielandt, D.; Schiller, M.; Bizzarro, M.

    2016-01-01

    Chromatographic purification of chromium (Cr), which is required for high-precision isotope analysis, is complicated by the presence of multiple Cr-species with different effective charges in the acid digested sample aliquots. The differing ion exchange selectivity and sluggish reaction rates of these species can result in incomplete Cr recovery during chromatographic purification. Because of large mass-dependent inter-species isotope fractionation, incomplete recovery can affect the accuracy of high-precision Cr isotope analysis. Here, we demonstrate widely differing cation distribution coefficients of Cr(III)-species (Cr3+, CrCl2+ and CrCl2+) with equilibrium mass-dependent isotope fractionation spanning a range of ~1‰/amu and consistent with theory. The heaviest isotopes partition into Cr3+, intermediates in CrCl2+ and the lightest in CrCl2+/CrCl3°. Thus, for a typical reported loss of ~25% Cr (in the form of Cr3+) through chromatographic purification, this translates into 185 ppm/amu offset in the stable Cr isotope ratio of the residual sample. Depending on the validity of the mass-bias correction during isotope analysis, this further results in artificial mass-independent effects in the mass-bias corrected 53Cr/52Cr (μ53 Cr* of 5.2 ppm) and 54Cr/52Cr (μ54Cr* of 13.5 ppm) components used to infer chronometric and nucleosynthetic information in meteorites. To mitigate these fractionation effects, we developed strategic chemical sample pre-treatment procedures that ensure high and reproducible Cr recovery. This is achieved either through 1) effective promotion of Cr3+ by >5 days exposure to HNO3 —H2O2 solutions at room temperature, resulting in >~98% Cr recovery for most types of sample matrices tested using a cationic chromatographic retention strategy, or 2) formation of Cr(III)-Cl complexes through exposure to concentrated HCl at high temperature (>120 °C) for several hours, resulting in >97.5% Cr recovery using a chromatographic elution strategy that

  11. Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis.

    PubMed

    Larsen, K K; Wielandt, D; Schiller, M; Bizzarro, M

    2016-04-22

    Chromatographic purification of chromium (Cr), which is required for high-precision isotope analysis, is complicated by the presence of multiple Cr-species with different effective charges in the acid digested sample aliquots. The differing ion exchange selectivity and sluggish reaction rates of these species can result in incomplete Cr recovery during chromatographic purification. Because of large mass-dependent inter-species isotope fractionation, incomplete recovery can affect the accuracy of high-precision Cr isotope analysis. Here, we demonstrate widely differing cation distribution coefficients of Cr(III)-species (Cr(3+), CrCl(2+) and CrCl2(+)) with equilibrium mass-dependent isotope fractionation spanning a range of ∼1‰/amu and consistent with theory. The heaviest isotopes partition into Cr(3+), intermediates in CrCl(2+) and the lightest in CrCl2(+)/CrCl3°. Thus, for a typical reported loss of ∼25% Cr (in the form of Cr(3+)) through chromatographic purification, this translates into 185ppm/amu offset in the stable Cr isotope ratio of the residual sample. Depending on the validity of the mass-bias correction during isotope analysis, this further results in artificial mass-independent effects in the mass-bias corrected (53)Cr/(52)Cr (μ(53)Cr* of 5.2ppm) and (54)Cr/(52)Cr (μ(54)Cr* of 13.5ppm) components used to infer chronometric and nucleosynthetic information in meteorites. To mitigate these fractionation effects, we developed strategic chemical sample pre-treatment procedures that ensure high and reproducible Cr recovery. This is achieved either through 1) effective promotion of Cr(3+) by >5 days exposure to HNO3H2O2 solutions at room temperature, resulting in >∼98% Cr recovery for most types of sample matrices tested using a cationic chromatographic retention strategy, or 2) formation of Cr(III)-Cl complexes through exposure to concentrated HCl at high temperature (>120°C) for several hours, resulting in >97.5% Cr recovery using a

  12. High-Performance Liquid Chromatographic and High-Performance Thin-Layer Chromatographic Method for the Quantitative Estimation of Dolutegravir Sodium in Bulk Drug and Pharmaceutical Dosage Form.

    PubMed

    Bhavar, Girija B; Pekamwar, Sanjay S; Aher, Kiran B; Thorat, Ravindra S; Chaudhari, Sanjay R

    2016-01-01

    Simple, sensitive, precise, and specific high-performance liquid chromategraphic (HPLC) and high-performance thin-layer chromatographic (HPTLC) methods for the determination of dolutegravir sodium in bulk drug and pharmaceutical dosage form were developed and validated. In the HPLC method, analysis of the drug was carried out on the ODS C18 column (150 × 4.6 mm, 5 μm particle size) using a mixture of acetonitrile: water (pH 7.5) in the ratio of 80:20 v/v as the mobile phase at the flow rate 1 mL/min at 260 nm. This method was found to be linear in the concentration range of 5-35 μg/mL. The peak for dolutegravir sodium was observed at 3.0 ± 0.1 minutes. In the HPTLC method, analysis was performed on aluminum-backed plates pre-coated with silica gel G60 F254 using methanol: chloroform: formic acid in the proportion of 8:2:0.5 v/v/v as the mobile phase. This solvent system was found to give compact spots for dolutegravir sodium with the Rf value 0.77 ± 0.01. Densitometric analysis of dolutegravir sodium was carried out in the absorbance mode at 265 nm. Linear regression analysis showed good linearity with respect to peak area in the concentration range of 200-900 ng/spot. The methods were validated for precision, limit of detection (LOD), limit of quantitation (LOQ), accuracy, and specificity. Statistical analysis showed that both of the methods are repeatable and specific for the estimation of the said drug. The methods can be used for routine quality control analysis of dolutegravir sodium. PMID:27222606

  13. High-Performance Liquid Chromatographic and High-Performance Thin-Layer Chromatographic Method for the Quantitative Estimation of Dolutegravir Sodium in Bulk Drug and Pharmaceutical Dosage Form

    PubMed Central

    Bhavar, Girija B.; Pekamwar, Sanjay S.; Aher, Kiran B.; Thorat, Ravindra S.; Chaudhari, Sanjay R.

    2016-01-01

    Simple, sensitive, precise, and specific high-performance liquid chromategraphic (HPLC) and high-performance thin-layer chromatographic (HPTLC) methods for the determination of dolutegravir sodium in bulk drug and pharmaceutical dosage form were developed and validated. In the HPLC method, analysis of the drug was carried out on the ODS C18 column (150 × 4.6 mm, 5 μm particle size) using a mixture of acetonitrile: water (pH 7.5) in the ratio of 80:20 v/v as the mobile phase at the flow rate 1 mL/min at 260 nm. This method was found to be linear in the concentration range of 5–35 μg/mL. The peak for dolutegravir sodium was observed at 3.0 ± 0.1 minutes. In the HPTLC method, analysis was performed on aluminum-backed plates pre-coated with silica gel G60 F254 using methanol: chloroform: formic acid in the proportion of 8:2:0.5 v/v/v as the mobile phase. This solvent system was found to give compact spots for dolutegravir sodium with the Rf value 0.77 ± 0.01. Densitometric analysis of dolutegravir sodium was carried out in the absorbance mode at 265 nm. Linear regression analysis showed good linearity with respect to peak area in the concentration range of 200–900 ng/spot. The methods were validated for precision, limit of detection (LOD), limit of quantitation (LOQ), accuracy, and specificity. Statistical analysis showed that both of the methods are repeatable and specific for the estimation of the said drug. The methods can be used for routine quality control analysis of dolutegravir sodium. PMID:27222606

  14. Simple and rapid high-performance liquid chromatographic method for the determination of aspartame and its metabolites in foods.

    PubMed

    Gibbs, B F; Alli, I; Mulligan, C N

    1996-02-23

    A method for the determination of aspartame (N-L-alpha-aspartyl-L-phenylalanine methyl ester) and its metabolites, applicable on a routine quality assurance basis, is described. Liquid samples (diet Coke, 7-Up, Pepsi, etc.) were injected directly onto a mini-cartridge reversed-phase column on a high-performance liquid chromatographic system, whereas solid samples (Equal, hot chocolate powder, pudding, etc.) were extracted with water. Optimising chromatographic conditions resulted in resolved components of interest within 12 min. The by-products were confirmed by mass spectrometry. Although the method was developed on a two-pump HPLC system fitted with a diode-array detector, it is straightforward and can be transformed to the simplest HPLC configuration. Using a single-piston pump (with damper), a fixed-wavelength detector and a recorder/integrator, the degradation of products can be monitored as they decompose. The results obtained were in harmony with previously reported tedious methods. The method is simple, rapid, quantitative and does not involve complex, hazardous or toxic chemistry. PMID:8900578

  15. Development and Validation of a Stability-Indicating Liquid Chromatographic Method for Estimating Olmesartan Medoxomil Using Quality by Design.

    PubMed

    Beg, Sarwar; Sharma, Gajanand; Katare, O P; Lohan, Shikha; Singh, Bhupinder

    2015-08-01

    The current studies entail systematic quality by design (QbD)-based development of a simple, rapid, sensitive and cost-effective stability-indicating method for the estimation of olmesartan medoxomil. Quality target method profile was defined and critical analytical attributes (CAAs) for the reverse-phase liquid chromatography method earmarked. Chromatographic separation accomplished on a C18 column using acetonitrile and water (containing 0.1% orthophosphoric acid, pH 3.5) in 40 : 60 (v/v) as mobile phase at a flow rate of 1.0 mL/min with UV detection at 243 nm. Risk assessment studies and screening studies facilitated comprehensive understanding of the factors affecting CAAs. The mobile phase ratio and flow rate were identified as critical method parameters (CMPs) and were systematically optimized using face-centered cubic design, evaluating for CAAs, namely peak area, retention time, theoretical plates and peak tailing. Statistical modelization was accomplished followed by response surface analysis for comprehending plausible interaction(s) among CMPs. Search for optimum solution was conducted through numerical and graphical optimization for demarcating the design space. Analytical method validation and subsequent forced degradation studies corroborated the method to be highly efficient for routine analysis of drug and its degradation products. The studies successfully demonstrate the utility of QbD approach for developing the highly sensitive liquid chromatographic method with enhanced method performance. PMID:25583970

  16. Gas-liquid chromatographic determination of total cholesterol in multicomponent foods.

    PubMed

    Punwar, J K

    1975-07-01

    A method is described for the determination of total cholesterol in multicomponent foods and also other products such as nonfat dry milk, dried whole egg solids, and certain candy bars. The lipid is extracted from the sample by a mixed solvent and saponified. The unsaponifiable fraction which contains the cholesterol and other sterols is extracted with benzene. An aliquot is evaporated to dryness and the residue is dissolved in dimethylformamide. The sterols are derivatized to form trimethylsilyl (TMS) ethers. The TMS-cholesterol derivative is quantitatively determined by gas-liquid chromatography, using 5alpha-cholestane as an internal standard. Nine laboratories participated in a collaborative study of the determination of total cholesterol in deviled ham sandwich spread, vegetable beef stew, corned beef hash, frozen chicken pot pie, pizza pepperoni, fish sticks, breaded shrimp, chocolate-covered candy bars, dried whole egg solids, and nonfat dry milk and the results are reported here. The coefficient of variation ranged from 5.64 to 23.2%, with an average coefficient of variation of 14.8%. PMID:1173811

  17. High-performance liquid chromatographic method for the determination of occupational exposure to the pesticide abamectin.

    PubMed

    Jongen, M J; Engel, R; Leenheers, L H

    1991-10-01

    As part of a survey of occupational exposure to pesticides in greenhouses for growing ornamentals, analytical methods were developed and validated for the measurement of exposure of workers to the pesticide abamectin. Abamectin consists of a mixture of avermectin-B1a and avermectin-B1b, which are members of a class of fermentation products of the soil microorganism Streptomyces Avermitilis. Because of the high molecular weight of the avermectins (greater than 800 daltons), high-performance liquid chromatography (HPLC) was the analytical method of choice. Previously described HPLC methods that used fluorescence detection were adapted and validated for the determination of dermal exposure by the analysis of cotton gloves and foliar dislodgeable residue. IOM samplers (developed at the Institute of Occupational Medicine, Edinburgh, U.K.) for collecting the inspirable fraction of dust or aerosols were tested for the determination of airborne abamectin concentrations in greenhouses. An analytical procedure considerably simpler than published methods appeared suitable for the determination of abamectin residues on cotton gloves and on greenhouse foliage. Analytical recovery from cotton gloves, solutions of foliar dislodgeable residues, and air-sampling filters was essentially complete. However, air concentrations of abamectin could not be reliably measured by using the IOM sampling device because of breakdown during sampling. Between-day coefficients of variation for solutions of dislodgeable residue and cotton glove extracts were between 3% and 6% for abamectin concentrations between 5 and 140 micrograms/L. PMID:1951054

  18. Organics Analyzer for Sampling Icy Surfaces: A liquid chromatograph-mass spectrometer for future in situ small body missions

    NASA Astrophysics Data System (ADS)

    Getty, Stephanie A.; Dworkin, Jason P.; Glavin, Daniel P.; Martin, Mildred; Zheng, Yun; Balvin, Manuel; Southard, Adrian E.; Feng, Steven; Ferrance, Jerome; Kotecki, Carl; Malespin, Charles; Mahaffy, Paul R.

    Liquid chromatography mass spectrometry (LC-MS) is an important laboratory technique for the detection and analysis of organic molecules with high sensitivity and selectivity. This approach has been especially fruitful in the analysis of nucleobases, amino acids, and measuring amino acid enantiomeric ratios in extraterrestrial materials. We are developing OASIS, Organics Analyzer for Sampling Icy Surfaces, for in situ analysis on future landed missions to astrochemically important icy bodies, such as asteroids, comets, and icy moons. The OASIS design employs a microfabricated, on-chip analytical column to chromatographically separate liquid analytes using known LC stationary phase chemistries. The elution products are then interfaced through spray ionization and analyzed by a time-of-flight mass spectrometer (TOF-MS). A particular advantage of our design is its suitability for microgravity environments, such as for a primitive small body.

  19. Chromatographic behaviour of steroidal saponins studied by high-performance liquid chromatography-mass spectrometry.

    PubMed

    Kite, Geoffrey C; Porter, Elaine A; Simmonds, Monique S J

    2007-05-01

    The chromatographic behaviour of steroidal saponins found in Anemarrhena asphodeloides, Asparagus officinalis, Convallaria majalis, Digitalis purpurea and Ruscus aculeatus was studied by HPLC-MS using a C-18 reversed-phase column and aqueous acetonitrile or aqueous methanol mobile phase gradients, with or without the addition of 1% acetic acid. The behaviour was compared to that of triterpene saponins found in Aesculus hippocastanum, Centella asiatica, Panax notoginseng and Potentilla tormentilla. Inclusion of methanol in the mobile phase under acidic conditions was found to cause furostanol saponins hydroxylated at C-22 to chromatograph as broad peaks, whereas the peak shapes of the spirostanol saponins and triterpene saponins studied remained acceptable. In aqueous methanol mobile phases without the addition of acid, furostanol saponins chromatographed with good peak shape, but each C-22 hydroxylated furostanol saponin was accompanied by a second chromatographic peak identified as its C-22 methyl ether. Methanolic extracts analysed in non-acidified aqueous acetonitrile mobile phases also resolved pairs of C-22 hydroxy and C-22 methoxy furostanol saponins. The C-22 methyl ether of deglucoruscoside was found to convert to deglucoruscoside during chromatography in acidified aqueous acetonitrile, or by dissolving in water. Poor chromatography of furostanol saponins in acidified aqueous methanol is due to the interconversion of the C-22 hydroxy and C-22 methoxy forms. It is recommended that initial analysis of saponins by HPLC-MS using a C-18 stationary phase is performed using acidified aqueous acetonitrile mobile phase gradients. The existence of naturally-occurring furostanol saponins methoxylated at C-22 can be investigated with aqueous acetonitrile mobile phases and avoiding methanol in the extraction solvent. PMID:17391684

  20. Evaluation and application of a mixed-mode chromatographic stationary phase in two-dimensional liquid chromatography for the separation of traditional Chinese medicine.

    PubMed

    Wei, Zhishen; Fu, Qing; Cai, Jianfeng; Huan, Liyun; Zhao, Jianchao; Shi, Hui; Jin, Yu; Liang, Xinmiao

    2016-06-01

    In this study, two mixed-mode chromatography stationary phases (C8SAX and C8SCX) were evaluated and used to establish a two-dimensional liquid chromatography system for the separation of traditional Chinese medicine. The chromatographic properties of the mixed-mode columns were systematically evaluated by comparing with other three columns of C8, strong anion exchanger, and strong cation exchanger. The result showed that C8SAX and C8SCX had a mixed-mode retention mechanism including electrostatic interaction and hydrophobic interaction. Especially, they were suitable for separating acidic and/or basic compounds and their separation selectivities could be easily adjusted by changing pH value. Then, several off-line 2D-LC systems based on the C8SAX in the first dimension and C8SAX, C8SCX, or C8 columns in the second dimension were developed to analyze a traditional Chinese medicine-Uncaria rhynchophylla. The two-dimensional liquid chromatography system of C8SAX (pH 3.0) × C8SAX (pH 6.0) exhibited the most effective peak distribution. Finally, fractions of U. rhynchophylla prepared from the first dimension were successfully separated on the C8SAX column with a gradient pH. Thus, the mixed-mode stationary phase could provide a platform to separate the traditional Chinese medicine in practical applications. PMID:27159545

  1. Fractional Josephson current through a Luttinger liquid with topological excitations

    SciTech Connect

    Wang, Rui; Wang, Baigeng Xing, D.Y.

    2015-07-15

    Recently, the Majorana fermion has received great attentions due to its promising application in the fault-tolerant quantum computation. This application requires more accessible methods to detect the motion and braiding of the Majorana fermions. We use a Luttinger liquid ring to achieve this goal, where the ring geometry is nontrivial in the sense that it leads to fermion-parity-dependent topological excitations. First, we briefly review the essential physics of the Luttinger liquid and the Majorana fermion, in order to give an introduction of the general framework used in the following main work. Then, we theoretically investigated the DC Josephson effect between two topological superconductors via a Luttinger liquid ring. A low-energy effective Hamiltonian is derived to show the existence of the fractional Josephson current. Also, we find that the amplitude of the Josephson current, which is determined by the correlation function of Luttinger liquid, exhibits different behaviors in terms of the parity of Luttinger liquid due to the topological excitations. Our results suggest a possible method to detect the Majorana fermions and their tunneling process.

  2. Simple, Fast and Reliable Liquid Chromatographic and Spectrophotometric Methods for the Determination of Theophylline in Urine, Saliva and Plasma Samples

    PubMed Central

    Charehsaz, Mohammad; Gürbay, Aylin; Aydin, Ahmet; Şahin, Gönül

    2014-01-01

    In this study, a high-performance liquid chromatographic method (HPLC) and UV spectrophotometric method were developed, validated and applied for the determination of theophylline in biological fluids. Liquid- liquid extraction is performed for isolation of the drug and elimination of plasma and saliva interferences. Urine samples were applied without any extraction. The chromatographic separation was achieved on a C18 column by using 60:40 methanol:water as mobile phase under isocratic conditions at a flow rate of 0.75 mL/min with UV detection at 280 nm in HPLC method. UV spectrophotometric analysis was performed at 275 nm. The results of HPLC analysis were as follows: the limit of quantification: 1.1 µg/mL for urine, 1.9 µg/mL for saliva, 3.1 µg/mL for plasma; recovery: 94.85% for plasma, 100.45% for saliva, 101.39% for urine; intra-day precision: 0.22–2.33%, inter-day precision: 3.17-13.12%. Spectrophotometric analysis results were as follows: the limit of quantitation: 5.23 µg/mL for plasma, 8.7 µg/mL for urine; recovery: 98.27% for plasma, 95.25% for urine; intra-day precision: 2.37 – 3.00%, inter-day precision: 5.43-7.91%. It can be concluded that this validated HPLC method is easy, precise, accurate, sensitive and selective for determination of theophylline in biological samples. Also spectrophotometric analysis can be used where it can be applicable. PMID:25237338

  3. Comparison of nano and conventional liquid chromatographic methods for the separation of (+)-catechin-ethyl-malvidin-3-glucoside diastereoisomers.

    PubMed

    Kučera, Lukáš; Fanali, Salvatore; Aturki, Zeineb; Pospíšil, Tomáš; Bednář, Petr

    2016-01-01

    Nano-liquid chromatography and conventional HPLC were used for the separation of diastereomers of (+)-catechin-ethyl-malvidin-3-glucoside. Those bridged anthocyanin dyes were obtained by reaction of (+)-catechin with malvidin-3-glucoside in the presence of acetaldehyde. Both diastereomers were isolated with semipreparative chromatography and their structures were confirmed by nuclear magnetic resonance and mass spectrometry. In-laboratory prepared capillary columns packed with fully porous particles Chromosphere C18, dp=3μm, core-shell particles Kinetex C18, dp=2.6μm (100μm i.d.) and monolithic column Chromolith CapRod (100μm i.d.) were used for the separation of (+)-catechin, malvidin-3-glucoside and both diastereomers. Chromosphere C18 stationary phase provided the best chromatographic performance. Mobile phase containing water:acetonitrile (80:20) acidified with trifluoroacetic acid (0.1%, v/v/v) was used in an isocratic elution mode with a flow rate of 360nLmin(-1). Separation of studied compounds was achieved in less than 7min under optimized conditions. The nano-liquid chromatographic method and a conventional HPLC one using the same fully porous particles (Chromosphere C18, 3μm, 100mm×4.6mm) were compared providing higher separation efficiency with the first analytical method and similar selectivity. A better peak symmetry and higher resolution of the studied diastereomers was achieved by conventional chromatography. Nevertheless, nano-liquid chromatography appeared to be useful for the separation of complex anthocyanin dyes and can be utilized for their analysis in plant and food micro-samples. The developed method was used for analysis of red wine grape pomace. PMID:26433264

  4. Fractionation of sugar cane with hot, compressed, liquid water

    SciTech Connect

    Allen, S.G.; Kam, L.C.; Zemann, A.J.; Antal, M.J. Jr.

    1996-08-01

    Sugar-cane bagasse and leaves (10--15 g oven-dry basis) were fractionated without size reduction by a rapid (45 s to 4 min), immersed percolation using only hot (190--230 C), compressed (P > P{sub sat}), liquid water (0.6--1.2 kg). Over 50% of the biomass could be solubilized. All of the hemicellulose, together with much of the acid-insoluble lignin in the bagasse (>60%), was solubilized, while less than 10% of the cellulose entered the liquid phase. Moreover, recovery of the hemicellulose as monomeric sugars (after a mild posthydrolysis) exceeded 80%. Less than 5% of the hemicellulose was converted to furfural. Percolation beyond that needed to immerse the biomass in hot liquid water did not result in increased solubilization. The yield of lignocellulosic residue was also not sensitive to the form of the sugar cane used (bagasse or leaves) or its moisture content (8--50%). Commercial applications for this fractionation process include the pretreatment of lignocellulosics for bioconversion to ethanol and the production of pulp and paper products.

  5. Classification of gasoline by octane number and light gas condensate fractions by origin with using dielectric or gas-chromatographic data and chemometrics tools.

    PubMed

    Rudnev, Vasiliy A; Boichenko, Alexander P; Karnozhytskiy, Pavel V

    2011-05-15

    The approach for classification of gasoline by octane number and light gas condensate fractions by origin with using dielectric permeability data has been proposed and compared with classification of same samples on the basis of gas-chromatographic data. The precision of dielectric permeability measurements was investigated by using ANOVA. The relative standard deviation of dielectric permeability was in the range from 0.3 to 0.5% for the range of dielectric permeability from 1.8 to 4.4. The application of exploratory chemometrics tools (cluster analysis and principal component analysis) allow to explicitly differentiate the gasoline and light gas condensate fractions into groups of samples related to specific octane number or origin. The neural networks allow to perfectly classifying the gasoline and light gas condensate fractions. PMID:21482310

  6. New reagents for enhanced liquid chromatographic separation and charging of intact protein ions for electrospray ionization mass spectrometry.

    PubMed

    Valeja, Santosh G; Tipton, Jeremiah D; Emmett, Mark R; Marshall, Alan G

    2010-09-01

    Electrospray ionization produces multiply charged ions, thereby lowering the mass-to-charge ratio for peptides and small proteins to a range readily accessed by quadrupole ion trap, orbitrap, and ion cyclotron resonance (ICR) mass analyzers (m/z = 400-2000). For Fourier transform mass analyzers (orbitrap and ICR), higher charge also improves signal-to-noise ratio, mass resolution, and mass accuracy. Addition of m-nitrobenzyl alcohol (m-NBA) or sulfolane has previously been shown to increase the charge states of proteins. Moreover, polar aprotic dimethylformamide (DMF) improves chromatographic separation of proteolytic peptides for mass analysis of solution-phase protein hydrogen/deuterium exchange for improved (78-96%) sequence coverage. Here, we show that addition of each of the various modifiers (DMF, thiodiglycol, dimethylacetamide, dimethylsulfoxide, and N-methylpyrrolidone) can significantly increase the charge states of proteins up to 78 kDa. Moreover, incorporation of the same modifiers into reversed-phase liquid chromatography solvents improves sensitivity, charging, and chromatographic resolution for intact proteins. PMID:20704305

  7. Development and validation of a liquid chromatographic-tandem mass spectrometric method for determination of eleven coccidiostats in milk.

    PubMed

    Nász, Szilárd; Debreczeni, Lajos; Rikker, Tamás; Eke, Zsuzsanna

    2012-07-15

    A reversed phase liquid chromatographic-tandem mass spectrometric method with simple solvent extraction and purification by solid phase extraction (SPE) has been developed for the determination of coccidiostats in milk. For sample preparation matrix solid phase dispersion, extraction by organic solvent and SPE with different cartridges were also tested. The compounds determined include lasalocid, narasin, salinomycin, monensin, semduramicin, maduramicin, robenidine, decoquinate, halofuginone, nicarbazin and diclazuril. Main steps of the method are addition of acetonitrile to the milk samples, centrifugation, removal of matrix by SPE, concentration by evaporation and LC-MS-MS determination. During a 15 min time segmented chromatographic run compounds are ionised either positively or negatively. Calculated recoveries range between 77.1% and 118.2%. Maximum levels are in the range of 1-20 μg/kg. The developed method was validated in line with the requirements of Commission Decision 2002/657/EC (2002). It is applicable for control of coccidiostat residues in milk as indicated in Regulation 124/2009/EC (2009). PMID:25683430

  8. Application of a sensitive liquid chromatographic/tandem mass spectrometric method to pharmacokinetic study of nalmefene in humans.

    PubMed

    Li, Ping; Chen, Xiaoyan; Dai, Xiaojian; Wen, Aidong; Zhang, Yifan; Zhong, Dafang

    2007-06-01

    A sensitive, specific and rapid liquid chromatographic/tandem mass spectrometric (LC/MS/MS) method was developed and validated for quantification of nalmefene in human plasma. An aliquot of 200 microL plasma sample was simply precipitated by 400 microL methanol. Separation of nalmefene and the internal standard hydromorphone from the interferences was achieved on a C(18) column followed by MS/MS detection. The analytes were monitored in the positive ionization mode with a TurboIonspray source. The method had a total chromatographic run time of 4.5 min and linear calibration curves over the concentration range of 10-5000 pg/mL. The lower limit of quantification (LLOQ) was 10 pg/mL. The intra- and inter-day precision was less than 10.1% determined from QC samples at concentrations of 30, 300 and 4500 pg/mL, and the accuracy was within +/-3.4%. As the method was more sensitive (10 times higher) than those reported previously, we investigated the pharmacokinetics of nalmefene in healthy volunteers after a single intravenous injection of low dose (30 microg) of nalmefene hydrochloride for the first time. PMID:17329173

  9. High-performance liquid chromatographic strategies for the determination and confirmation of anticoagulant rodenticide residues in animal tissues.

    PubMed

    Hunter, K

    1985-03-15

    A comprehensive approach to the analysis of anticoagulant rodenticide residues in animal tissues based on high-performance liquid chromatography (HPLC) has been developed. Residues of warfarin, coumatetralyl, difenacoum, brodifacoum, bromadiolone, diphacinone and chlorophacinone were extracted with chloroformacetone (1:1, v/v). Extracts were cleaned-up by an integrated gel permeation and adsorption chromatographic procedure which divided the rodenticides into two groups. Residues were then determined and confirmed using normal-phase, ion-pair and weak ion-exchange HPLC techniques. Ion-pair gradient separation resolved all seven rodenticides in a single chromatographic analysis. UV detection methods were employed for all seven rodenticides. Use of a diode array detection system permitted additional confirmation of residues down to 0.1 mg kg-1 by matching UV spectra and derivatives of spectra. Sensitive fluorescence detection was possible for the coumarin-based rodenticides but not for diphacinone and chlorophacinone. Post-column pH-switching fluorescence detection methods were shown to be superior to other methods of fluorescence detection of coumarin-based rodenticides. Recoveries from spiked liver tissue were around 90% at levels from 0.05 to 1 mg kg-1. Detection limits of around 0.002 mg kg-1 for most rodenticides and of 0.01 mg kg-1 for warfarin could be achieved with animal tissue extracts. PMID:3988841

  10. Determination of Cefadroxil in Tablet/Capsule formulations by a validated Reverse Phase High Performance Liquid Chromatographic method.

    PubMed

    Rahim, Najia; Naqvi, Syed Baqir-Shyum; Shakeel, Sadia; Iffat, Wajiha; Muhammad, Iyad Naeem

    2015-07-01

    An innovative, selective and rapid reversed phase High Performance Liquid Chromatographic (RP-HPLC) method for the analysis of cefadroxil in bulk material and oral solid dosage forms has been developed and validated. The chromatographic system consisted of Sil-20A auto sampler, LC-20A pump and SPD-20A UV/visible detector. The separation was achieved by C18 column at ambient temperature with a mobile phase consisting of methanol: Phosphate buffer (10: 90) at a flow rate of 1.5 ml/min. The method is reproducible, repeatable (%RSD for intra-day and inter-day ranged between 1.75-5.33% and 0.58-2.69%) and linear (R2=0.9935). The LOD and LOQ of the method were 0.5 and 1.0 μg/ml, respectively. The present RP-HPLC method was found to be sensitive, accurate, precise, rapid and cost effective that can be efficiently used in QC/QA laboratories for routine analysis of the raw materials as well as oral dosage formulations of cefadroxil. PMID:26142506

  11. Evaluation of the retention pattern on ionic liquid columns for gas chromatographic analyses of fatty acid methyl esters.

    PubMed

    Lin, Chen-Chen; Wasta, Ziar; Mjøs, Svein A

    2014-07-11

    Fatty acid methyl esters from marine sources were analyzed by gas chromatography-mass spectrometry on three ionic liquid columns, SLB-IL61, SLB-IL82 and SLB-IL100 (Supelco). Retention indices (equivalent chain lengths) are reported for more than 100 compounds and the overlap patterns are evaluated from these data. The influence of chromatographic conditions on the retention indices of unsaturated fatty acid methyl esters is also evaluated. Compared to typical alternative phases the retention patterns on all three columns are highly dependent on the conditions. The SLB-IL61 phase had overlaps between nutritionally important fatty acids that could not be resolved by changing the chromatographic conditions. This column is therefore regarded as unsuitable for clinical and nutritional studies of the fatty acid composition, but similar overlaps may be avoided on IL82 and IL100. On all three columns double bonds close to the carboxyl group in the analytes contribute with limited retention, which makes it challenging to predict the retention of polyunsaturated fatty acid methyl esters. PMID:24873965

  12. Differential chemical derivatization integrated with chromatographic separation for analysis of isomeric sialylated N-glycans: a nano-hydrophilic interaction liquid chromatography-MS platform.

    PubMed

    Tousi, Fateme; Bones, Jonathan; Hancock, William S; Hincapie, Marina

    2013-09-01

    MS analysis of sialylated glycans is challenging due to their low ionization efficiency in positive ion mode as well as the possibility of in-source fragmentation. Chemical derivatization strategies have been developed to address this issue focused on removal of the labile acidic proton prior to MS analysis. Highly sialylated negatively charged glycans also exhibit high retention and unsatisfactory separation efficiency when analyzed by hydrophilic interaction liquid chromatography (HILIC) due to their high polarity. Here, we combined linkage specific derivatization of sialic acids by reaction with the condensation reagent 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM) in methanol with nanoscale liquid chromatographic separation prior to accurate mass Orbitrap MS analysis. Coupling DMT-MM charge neutralization of sialic acids with nano-HILIC-Orbitrap-MS not only allows for linkage specific characterization of sialylated glycans directly from the precursor mass but also improves the preceding HILIC separation by increasing the hydrophobicity and altering the selectivity of the oligosaccharide analytes. We focused on the trisialylated N-glycan fraction from haptoglobin and human plasma, enriched using weak anion exchange chromatography, as this trisialylated fraction has been linked with cancer associated changes in the serum N-glycome. The developed methodology was applied to investigate whether structural alterations in this oligosaccharide pool, enriched from the sera of pathological stage and sex matched patients bearing lung, breast, ovarian, pancreatic, or gastric cancer, demonstrate any degree of cancer specificity or whether changes in expression levels are purely cancer associated. The results of this pilot study indicate limited degrees of cancer specificity, particularly for pancreatic cancer, based on alterations in the relative abundance of specific trisialylated isomers. PMID:23901877

  13. High-performance liquid chromatographic procedure for the simultaneous determination of norfloxacin, fenbufen and felbinac in rat plasma.

    PubMed

    Katagiri, Y; Naora, K; Ichikawa, N; Hayashibara, M; Iwamoto, K

    1989-10-01

    A high-performance liquid chromatographic method for the simultaneous determination of norfloxacin, fenbufen and felbinac extracted from 50 microliters of rat plasma is described. Chromatography was performed on a reversed-phase column with ultraviolet detection. By the present method, quantitative and reproducible determinations were possible for norfloxacin, fenbufen and felbinac over the concentration ranges of 0.2-20, 0.2-120 and 0.4-40 micrograms/ml, respectively. The recoveries of norfloxacin, fenbufen and felbinac added to plasma were nearly 100% with a coefficient of variation of less than 8.0%. This method was found to be applicable to pharmacokinetic studies of each drug after the concomitant administration of norfloxacin and fenbufen. PMID:2611947

  14. High-performance liquid chromatographic determination of loracarbef, a potential metabolite, cefaclor and cephalexin in human plasma, serum and urine.

    PubMed

    Kovach, P M; Lantz, R J; Brier, G

    1991-06-14

    A high-performance liquid chromatographic (HPLC) method is reported for the determination of a new carbacephem antibiotic, loracarbef, a hydroxylated analogue, and two cephalosporins, cefaclor and cephalexin, in plasma, serum, and urine. The antibiotics are extracted from plasma by means of C18 solid-phase cartridges. Urine samples are diluted with water and directly injected on the HPLC system. The HPLC system utilizes a Supelcosil LC-18-DB (250 mm x 4.6 mm I.D.) reversed-phase column and ultraviolet detection at 265 nm. The limit of quantitation is 0.5 micrograms/ml for each compound. Excellent correlation of plasma concentrations is shown between results determined by HPLC and those obtained by microbiological agar-well diffusion assays. Stability studies of loracarbef in human plasma show the antibiotic to be stable for at least 24 h at room temperature and for at least twelve months at -20 degrees C. PMID:1918240

  15. 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.

  16. Development and validation of a high-performance liquid chromatographic method for the analysis of propylthiouracil in pharmaceuticals.

    PubMed

    Abdul-Fattah, A M; Bhargava, H N

    2001-09-01

    A simple, rapid, and stability-indicating high-performance liquid chromatographic (HPLC) method was developed and validated for the assay of propylthiouracil (PTU). The method was used to quantify PTU in topical formulations and in tablets. Excellent linearity was observed between PTU concentration and the peak area (R2= 0.999). The limit of detection was 1 ng, and the limit of quantitation was 1.2 ng. The method proved to be selective. Selectivity was validated by subjecting a stock solution of PTU to acidic, basic, and oxidative degradations. The peaks of the degradation products did not interfere with the peak of PTU. Excipients present in the dosage forms did not interfere with the analysis, and the recovery of PTU from each dosage form was quantitative. PMID:11699835

  17. [Diol column as stationary phase for high performance liquid chromatographic analysis of carbohydrates in drinks with evaporative light scattering detection].

    PubMed

    Wei, Y; Guo, L; Ding, M Y

    2001-11-01

    A high performance liquid chromatographic method with a diol column and evaporative light scattering detector (ELSD) was established for the direct analysis of fructose, glucose, sucrose, maltose and raffinose in mixture. A separation column (Lichrospher 100 Diol, 250 mm x 4.0 mm i.d., 5 microns, Hewlett-Packard, USA) and a guard column (Zorbax Rx-SIL, 12.5 mm x 4.6 mm i.d., 5 microns) were used. The mobile phase was a mixture of dichloromethane-methanol (3.2:1, volume ratio). Regression equations revealed linear relationship (correlation coefficients: 0.995-0.999) between the mass of carbohydrates injected and the peak area of carbohydrates detected by ELSD. The detection limits of ELSD (S/N = 3) were about 0.20 microgram for all carbohydrates. This system could be used for the routine analysis of simple carbohydrates in some common drinks on market. PMID:12545463

  18. [Preparation and chromatographic performance of a eugenol-bonded silica gel stationary phase for high performance liquid chromatography].

    PubMed

    Xu, Lili; Zhong, Minghua; Chen, Xiaojing

    2015-05-01

    A eugenol-bonded silica gel stationary phase (EGSP) for high performance liquid chromatography ( HPLC) has been synthesized by the solid-liquid successive reaction method. The preparation process included two steps: firstly, γ-glycidoxypropyltrimethoxy-silane (KH-560) was covalently attached to the surface of spherical silica gel. Then the bonded silica gel continued to react with eugenol ligand, which was a plant active component, and obtained EGSP. The structure of EGSP was characterized by elemental analysis, thermogravimetric analysis and Fourier transform infrared spectroscopy. Using naphthalene as a probe, the column efficiency was tested under the mobile phase of acetonitrile-water (35:65, v/v) at a flow rate of 0.8 mL/min. The chromatographic properties and the retention mechanism of EGSP were evaluated by using neutral, basic and acidic analytes as solute probes. Meanwhile, the comparative study with C18 column and phenyl column was also carried out under the same chromatographic conditions. The result showed that the eugenol ligand was successfully bonded to the surface of silica gel with a 0.28 mmol/g of bonded amount, and the theoretical plate number of EGSP column was about 24 707 N/m. The EGSP appeared to be a kind of excellent reversed-phase stationary phase with suitable hydrophobicity and various synergistic sites. The eugenol ligand bonded on silica gel could first provide π-π interaction sites for different analytes because of its benzene ring and alkenyl. In addition, the methoxy groups of eugenol were responsible for dipole-dipole and hydrogen-bonding interactions between the ligand and solutes in the effective separation process. Comparing with traditional C18 column and phenyl column, EGSP has an advantage in the fast separation of polar compounds under simple experimental conditions. PMID:26387202

  19. Simultaneous derivatisation and preconcentration of parabens in food and other matrices by isobutyl chloroformate and dispersive liquid-liquid microextraction followed by gas chromatographic analysis.

    PubMed

    Jain, Rajeev; Mudiam, Mohana Krishna Reddy; Chauhan, Abhishek; Ch, Ratnasekhar; Murthy, R C; Khan, Haider A

    2013-11-01

    A simple, rapid and economical method has been proposed for the quantitative determination of parabens (methyl, ethyl, propyl and butyl paraben) in different samples (food, cosmetics and water) based on isobutyl chloroformate (IBCF) derivatisation and preconcentration using dispersive liquid-liquid microextraction in single step. Under optimum conditions, solid samples were extracted with ethanol (disperser solvent) and 200 μL of this extract along with 50 μL of chloroform (extraction solvent) and 10 μL of IBCF was rapidly injected into 2 mL of ultra-pure water containing 150 μL of pyridine to induce formation of a cloudy state. After centrifugation, 1 μL of the sedimented phase was analysed using gas chromatograph-flame ionisation detector (GC-FID) and the peaks were confirmed using gas chromatograph-positive chemical ionisation-mass spectrometer (GC-PCI-MS). Method was found to be linear over the range of 0.1-10 μg mL(-1) with square of correlation coefficient (R(2)) in the range of 0.9913-0.9992. Limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.029-0.102 μg mL(-1) and 0.095-0.336 μg mL(-1) with a signal to noise ratio of 3:1 and 10:1, respectively. PMID:23768377

  20. LIQUID AND GAS CHROMATOGRAPHIC ANALYSIS OF DIETHYL PHTHALATE IN WATER AND SEDIMENT

    EPA Science Inventory

    Diethyl phthalate was determined in water and sediment by high performance liquid chromatography (HPLC) and in water by gas-liquid chromatography with electron capture detection (GLC-ECD). Water samples were extracted with hexane, using a high-speed homogenizer-ultrasonic apparat...

  1. Polyanionic and polyzwitterionic azobenzene ionic liquid-functionalized silica materials and their chromatographic applications.

    PubMed

    Qiu, Hongdeng; Jiang, Shengxiang; Takafuji, Makoto; Ihara, Hirotaka

    2013-03-25

    New polyanionic and polyzwitterionic azobenzene ionic liquid-functionalized silica materials were designed based on the preparation of a new polymerizable azobenzene anionic monomer and either its cation-exchange with alkylimidazolium after grafting or the formation of an ionic liquid monomer pair before grafting onto silica. PMID:23417018

  2. Determination of rizatriptan in human plasma by liquid chromatographic-eletrospray tandem mass spectrometry: application to a pharmacokinetic study.

    PubMed

    Guo, Ji-fen; Zhang, Ai-jun; Zhao, Ling; Sun, Xiao-hong; Zhao, Yi-min; Gao, Hong-zhi; Liu, Ze-yuan; Qiao, Shan-yi

    2006-01-01

    A sensitive liquid chromatographic-tandem mass spectrometry(LC-MS/MS) method was developed for the determination of rizatriptan in human plasma. The analytes were extracted from plasma samples by liquid-liquid extraction, separated on a Zorbax XDB C8 column (150 x 4.6 mm i.d.) and detected by tandem mass spectrometry with an electrospray ionization interface. Zomitriptan was used as the internal standard. The method had a lower limit of quantitation of 50 pg/mL for rizatriptan, which showed more sensitivity and speed of analysis compared with reported methods. The within- and between-day precision was measured to be below 11.71% and accuracy between -5.87 and 0.86% for all quality control samples. This quantitation method was successfully applied to the evaluation of the pharmacokinetic profiles of rizatriptan after single oral administration of 5, 10 and 15 mg rizatriptan tablets to 10 healthy volunteers (five males and five females). PMID:15954161

  3. Fractionation in Gay-Berne liquid crystal mixtures

    NASA Astrophysics Data System (ADS)

    Moreno-Razo, J. Antonio; Díaz-Herrera, Enrique; Klapp, Sabine H. L.

    2007-10-01

    We present a constant-pressure molecular dynamics simulation study of the phase behavior of binary (50:50) Gay-Berne liquid crystal mixtures consisting of elongated particles with different lengths (LA>LB) and equal diameters. We focus on systems at dense liquid-state conditions. Considering three mixtures characterized by different values of LA(B) and different length ratios q=LB/LA<1 , we find complex fluid-fluid phase behavior resulting from the interplay between nematic, smectic- A -type, or smectic- B -type orientational ordering, on the one hand, and demixing into two phases of different composition (fractionation), on the other hand. The driving “forces” of demixing transitions are the temperature and the length ratio. Indeed, in the system characterized by the largest value of q (q=0.86) orientational order occurs already in mixed states, whereas full fractionation is found at q=0.71 . The two resulting states are either of type smectic- B -nematic (intermediate temperatures) or smectic- B -smectic- B (low temperatures). In the intermediate case q=0.80 we observe a stepwise ordering and demixing behavior on cooling the system from high temperatures. Moreover, our results show that the stability range of (partially) nematic structures in mixtures of sufficiently small q can be significantly larger than in the pure counterparts, in qualitative agreement with experimental observations.

  4. Fractionation in Gay-Berne liquid crystal mixtures.

    PubMed

    Moreno-Razo, J Antonio; Díaz-Herrera, Enrique; Klapp, Sabine H L

    2007-10-01

    We present a constant-pressure molecular dynamics simulation study of the phase behavior of binary (50:50) Gay-Berne liquid crystal mixtures consisting of elongated particles with different lengths (LA>LB) and equal diameters. We focus on systems at dense liquid-state conditions. Considering three mixtures characterized by different values of LA(B) and different length ratios q=LB/LA<1, we find complex fluid-fluid phase behavior resulting from the interplay between nematic, smectic-A-type, or smectic-B-type orientational ordering, on the one hand, and demixing into two phases of different composition (fractionation), on the other hand. The driving "forces" of demixing transitions are the temperature and the length ratio. Indeed, in the system characterized by the largest value of q (q=0.86) orientational order occurs already in mixed states, whereas full fractionation is found at q=0.71. The two resulting states are either of type smectic-B-nematic (intermediate temperatures) or smectic-B-smectic-B (low temperatures). In the intermediate case q=0.80 we observe a stepwise ordering and demixing behavior on cooling the system from high temperatures. Moreover, our results show that the stability range of (partially) nematic structures in mixtures of sufficiently small q can be significantly larger than in the pure counterparts, in qualitative agreement with experimental observations. PMID:17995009

  5. INTERLABORATORY STUDY OF A THERMOSPRAY-LIQUID CHROMATOGRAPHIC/MASS SPECTROMETRIC METHOD FOR SELECTED N-METHYL CARBAMATES, N-METHYL CARBAMOYLOXIMES, AND SUBSTITUTED UREA PESTICIDES

    EPA Science Inventory

    A thermospray-liquid chromatographic/mass spectrometric (TS-LC/MS) method was evaluated in an interlaboratory study for determining 3 N-methyl carbamates (bendiocarb, carbaryl, and carbofuran), 3-N-methyl carbamoyloximes (aldicarb, methomyl, and oxamyl), 2 substituted urea pestic...

  6. Chromatographic sample collection from two-phase (gas+liquid) flows.

    PubMed

    Bruno, Thomas J; Windom, Bret C

    2011-12-01

    A particularly challenging sample presentation in analytical chemistry is a flowing stream that consists of both a gas and liquid phase, combined with the common situation in which a reliable analysis is needed for both phases, separately. In these cases, the vapor and liquid must be physically separated (without change to either), before the individual phases can be collected and analyzed. It is not possible to analyze two-phase flows otherwise. Although the two phases are at equilibrium, it is imperative that no liquid contaminate the vapor, and no vapor be entrained in the liquid at a given temperature and pressure. In this paper, we describe a simple on-line device that can individually separate and collect the vapor and liquid phases of a two-phase flow. The apparatus, which we call P(2)SC, uses an adaptation of the branch point separator, with vapor collection done downstream in a metal bellows. The liquid collection is done in a length of Teflon tube. The separated vapor and liquid phases are then easily transferred into any desired analytical instrument with a syringe, although any sample introduction method, such as a valve, could be used as well. We discuss the application of this device with a stream of thermally stressed rocket kerosene. PMID:22036084

  7. Experimental determination of the Si isotope fractionation factor between liquid metal and liquid silicate

    NASA Astrophysics Data System (ADS)

    Hin, Remco C.; Fitoussi, Caroline; Schmidt, Max W.; Bourdon, Bernard

    2014-02-01

    The conditions of core formation and the abundances of the light elements in Earth's core remain debated. Silicon isotope fractionation provides a tool contributing to this subject. We present experimentally determined Si isotope fractionation factors between liquid metal and liquid silicate at 1450 °C and 1750 °C, which allow calibrating the temperature dependence of Si isotope fractionation. Experiments were performed in a centrifuging piston cylinder at 1 GPa, employing both graphite and MgO capsules. Tin was used to lower the melting temperature of the metal alloys for experiments performed at 1450 °C. Tests reveal that neither Sn nor C significantly affects Si isotope fractionation. An alkaline fusion technique was employed to dissolve silicate as well as metal phases prior to ion exchange chemistry and mass spectrometric analysis. The results show that metal is consistently enriched in light isotopes relative to the silicate, yielding average metal-silicate fractionation factors of -1.48±0.08‰ and -1.11±0.14‰ at 1450 °C and 1750 °C, respectively. The temperature dependence of equilibrium Si isotope fractionation between metal and silicate can thus be described as Δ30SiMetal-Silicate=-4.42(±0.05)×106/T2. The Si isotope equilibrium fractionation is thus about 1.7 times smaller than previously proposed on the basis of experiments. A consequence of this smaller fractionation is that the calculated difference between the Si isotope composition of the bulk Earth and that of the bulk silicate Earth generated by core formation is smaller than previously thought. It is therefore increasingly difficult to match the Si isotope composition of the bulk silicate Earth with that of chondrites for metal-silicate equilibration temperatures above ∼2500 K. This suggests that Si isotopes were more sensitive to the early stages of core formation when low oxygen fugacities allowed significant incorporation of Si into metal.

  8. Glycosylated haemoglobin: high-performance liquid chromatographic determination of 5-(hydroxymethyl)-2-furfuraldehyde after haemoglobin hydrolysis.

    PubMed

    Ménez, J F; Berthou, F; Meskar, A; Picart, D; Le Bras, R; Bardou, L G

    1984-08-01

    A specific and accurate method for the quantitation of the azomethine linkage present in non-enzymatically glycosylated haemoglobin is described. This protein is hydrolysed for 5 h in 1 M oxalic acid at 100 degrees C to yield 5-(hydroxymethyl)-2-furfur-aldehyde (5-HMF), known as a specific degradation product of hexoses linked to the protein. 5-HMF is then purified through a Sep-Pak C18 cartridge and measured by its absorption at 280 nm after separation on a C18 reversed-phase silica column. Quantitation is made accurate by using 1-methylxanthine as internal standard throughout the whole procedure. The identity and the purity of the 5-HMF chromatographic peak was ascertained by UV spectroscopy, gas chromatography on a glass capillary column and mass spectrometry. The method has been successfully used for 5-HMF determinations in monitoring diabetes mellitus patients. The mean values, expressed as nmol of 5-HMF per mg of haemoglobin were 0.64 +/- 0.13 (S.D.) for 27 controls and 1.32 +/- 0.39 for 78 diabetic patients. Unlike the usually employed thiobarbituric acid assay, the present procedure is truly specific for the 5-HMF determination. PMID:6490766

  9. Liquid chromatographic analysis of glucosamine in commercial dietary supplements using indirect fluorescence detection.

    PubMed

    Shen, Xiaoxuan; Yang, Min; Tomellini, Sterling A

    2007-02-01

    A method of using indirect fluorescence detection is evaluated for the analysis of glucosamine in commercial dietary supplements following chromatographic separation. In this method, the eluting analyte, glucosamine, was detected by monitoring an increase in the fluorescence signal for L-tryptophan (L-Trp) or DL-5-methoxytryptophan (5-MTP) after glucosamine complexed with a copper(II) ion and released either L-Trp or 5-MTP from a copper(II) complex, which is introduced postcolumn. The fluorescence of L-Trp and 5-MTP are quenched when complexed with the copper(II) ion. The results obtained using indirect fluorescence detection are compared with the results obtained for precolumn derivatization with phenylisothiocyanate. Statistical analysis is performed to compare the results obtained for the two postcolumn interaction components, Cu(L-Trp)2 and Cu(5-MTP)2, as well as the results obtained using the indirect fluorescence detection method and a precolumn derivatization method. The indirect fluorescence detection method provided an alternative to precolumn derivatization for determining the concentration of glucosamine in commercial dietary supplements. The stability of the glucosamine-o-phthalaldehyde-3-mercaptopropionic acid derivative is also evaluated to investigate the applicability of the popular precolumn derivatization reagent, o-phthalaldehyde-3-mercaptopropionic acid, for this analysis. PMID:17425135

  10. Quantitative Analysis of Resorcinol from Marketed Hair Tonic Using Liquid Chromatographic Technique

    PubMed Central

    De, Amit Kumar; Chowdhury, Partha Pratim; Chattapadhyay, Shyamaprasad

    2014-01-01

    Quantitative estimation of resorcinol from marketed pharmaceutical formulation has been reported in this study. Resorcinol as a pharmaceutical ingredient has a broad spectrum of application but its application is limited due to its toxic side effects. Method for the accurate estimation of resorcinol is therefore essential. In the current study we have developed a chromatographic technique for its estimation from a marketed hair tonic meant for the treatment of several dermatological diseases of the scalp. A stainless steel column 25 cm in length and 4 mm internal diameter packed with octadecylsilane (5 µm) was used for this purpose. The mobile phase was a mixture of phosphate buffer of pH 2.8 and acetonitrile. The flow rate was 0.6 mL·min−1 and the detection wavelength was 280 nm. The method was found to be linear between concentration range 10.28 µg·mL−1 to 71.96 µg·mL−1 with r2 value 0.999. The accuracy of the method and the intraday and interday precession study presents the applicability of the method for the estimation of resorcinol from any pharmaceutical and cosmetic product containing resorcinol. PMID:27379340

  11. High Performance Liquid Chromatographic Analysis of Almotriptan Malate in Bulk and Tablets

    PubMed Central

    Lavudu, Petikam; Rani, Avula Prameela; Divya, Chepuri; Sekharan, Chandra Bala

    2013-01-01

    Purpose: A simple RP-HPLC method has been developed and validated for the determination of almotriptan malate (ATM) in bulk and tablets. Methods: Chromatographic separation of ATM was achieved by using a Thermo Scientific C18 column. A Mobile phase containing a mixture of methanol, water and acetic acid (4:8:0.1 v/v) was pumped at the flow rate of 1 mL/min. Detection was performed at 227 nm. According to ICH guidelines, the method was validated. Results: The calibration curve was linear in the concentration range 5–60 µg/mL for the ATM with regression coefficient 0.9999. The method was precise with RSD <1.2%. Excellent recoveries of 99.60 - 100.80% proved the accuracy of the method. The limits of detection and quantification were found to be 0.025 and 0.075 µg/mL, respectively. Conclusion: The method was successfully applied for the quantification of ATM in tablets with acceptable accuracy and precision. PMID:24312833

  12. Liquid chromatographic resolution of mexiletine and its analogs on crown ether-based chiral stationary phases.

    PubMed

    Jin, Kab Bong; Kim, Hee Eun; Hyun, Myung Ho

    2014-05-01

    Mexiletine, an effective class IB antiarrhythmic agent, and its analogs were resolved on three different crown ether-based chiral stationary phases (CSPs), one (CSP 1) of which is based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid and the other two (CSP 2 and CSP 3) are based on (3,3'-diphenyl-1,1'-binaphthyl)-20-crown-6. Mexiletine was resolved with a resolution (R(S)) of greater than 1.00 on CSP 1 and CSP 3 containing residual silanol group-protecting n-octyl groups on the silica surface, but with a resolution (R(S)) of less than 1.00 on CSP 2. The chromatographic behaviors for the resolution of mexiletine analogs containing a substituted phenyl group at the chiral center on the three CSPs were quite dependent on the phenoxy group of analytes. Namely, mexiletine analogs containing 2,6-dimethylphenoxy, 3,4-dimethylphenoxy, 3-methylphenoxy, 4-methylphenoxy, and a simple phenoxy group were resolved very well on the three CSPs even though the chiral recognition efficiencies vary with the CSPs. However, mexiletine analogs containing 2-methylphenoxy group were not resolved at all or only slightly resolved. Among the three CSPs, CSP 3 was found to show the highest chiral recognition efficiencies for the resolution of mexiletine and its analogs, especially in terms of resolution (R(S)). PMID:24677299

  13. Characterization and multi-mode liquid chromatographic application of 4-propylaminomethyl benzoic acid bonded silica--a zwitterionic stationary phase.

    PubMed

    Wijekoon, A; Gangoda, M E; Gregory, R B

    2012-12-28

    solvent content in the aqueous mobile phase. An increase in retention with decreasing water content in the mobile phase was observed, consistent with a hydrophilic interaction liquid chromatographic (HILIC) mode of separation. PMID:23200307

  14. High performance liquid chromatographic determination of aflatoxins in chilli, peanut and rice using silica based monolithic column.

    PubMed

    Khayoon, Wejdan Shakir; Saad, Bahruddin; Lee, Tien Ping; Salleh, Baharuddin

    2012-07-15

    A simple and rapid high performance liquid chromatographic with fluorescence detection method for the determination of the aflatoxin B1, B2, G1 and G2 in peanuts, rice and chilli was developed. The sample was extracted using acetonitrile:water (90:10, v/v%) and then purified by using ISOLUTE® multimode solid phase extraction. After the pre-column derivatisation, the analytes were separated within 3.7 min using Chromolith® performance RP-18e (100-4.6mm) monolithic column. To assess the possible effects of endogenous components in the food items, matrix-matched calibration was used for the quantification and validation. The recoveries of aflatoxins that were spiked into food samples were 86.38-104.5% and RSDs were <4.4%. The method was applied to the determination of aflatoxins in peanut (9), rice (5) and chilli (10) samples. Liquid chromatography-tandem mass spectrometry analysis using triple quadruple analyser and operated in the multiple reaction monitoring modes on the contaminated samples was performed for confirmation. PMID:25683424

  15. Ultra-high performance liquid chromatographic determination of antioxidants in teas using inkjet-printed graphene-polyaniline electrode.

    PubMed

    Bardpho, Chayanee; Rattanarat, Poomrat; Siangproh, Weena; Chailapakul, Orawon

    2016-02-01

    A development of ultra-high performance liquid chromatographic coupled with a novel inkjet-printed conductive ink-modified electrode for a fast and simultaneous determination of polyphenolic antioxidants was achieved. Two printing techniques were selected for fabrication and modification including (i) an in-house screen-printing method and (ii) an inkjet-printing method, respectively. A conductive ink containing graphene and polyaniline nanocomposite (G-PANI) was precisely casted onto the surface of screen-printed carbon electrode (SPCE) using a dimatix inkjet material printer. Compared to a bare SPCE, the G-PANI-modified screen-printed carbon electrode (G-PANI/SPCE) exhibited higher electrochemical sensitivity with increase (2-4 times) of peak current of each antioxidant. Moreover, four antioxidants were successfully separated and determined within 3 min using a reverse phase ultra-high performance liquid chromatography (UHPLC) with a mobile phase containing phosphate buffer and acetonitrile (90:10 v/v). Under an optimal detection potential at +1.2V vs. Ag/AgCl, linear calibrations and limits of detection (S/N=3) for antioxidants were found to be 0.01-10 µg mL(-1) and 1.38-1.94 ng mL(-1), respectively. Finally, this proposed method has been successfully used for the determination of antioxidants in tea samples, the results obtained from our presented method were within a highly good agreement those obtained from a standard UHPLC-UV method. PMID:26653500

  16. Characterization of Chinese rice wine taste attributes using liquid chromatographic analysis, sensory evaluation, and an electronic tongue.

    PubMed

    Yu, HaiYan; Zhao, Jie; Li, Fenghua; Tian, Huaixiang; Ma, Xia

    2015-08-01

    To evaluate the taste characteristics of Chinese rice wine, wine samples sourced from different vintage years were analyzed using liquid chromatographic analysis, sensory evaluation, and an electronic tongue. Six organic acids and seventeen amino acids were measured using high performance liquid chromatography (HPLC). Five monosaccharides were measured using anion-exchange chromatography. The global taste attributes were analyzed using an electronic tongue (E-tongue). The correlations between the 28 taste-active compounds and the sensory attributes, and the correlations between the E-tongue response and the sensory attributes were established via partial least square discriminant analysis (PLSDA). E-tongue response data combined with linear discriminant analysis (LDA) were used to discriminate the Chinese rice wine samples sourced from different vintage years. Sensory evaluation indicated significant differences in the Chinese rice wine samples sourced from 2003, 2005, 2008, and 2010 vintage years in the sensory attributes of harmony and mellow. The PLSDA model for the taste-active compounds and the sensory attributes showed that proline, fucose, arabinose, lactic acid, glutamic acid, arginine, isoleucine, valine, threonine, and lysine had an influence on the taste characteristic of Chinese rice wine. The Chinese rice wine samples were all correctly classified using the E-tongue and LDA. The electronic tongue was an effective tool for rapid discrimination of Chinese rice wine. PMID:26113454

  17. Matrix solid-phase dispersion (MSPD) isolation and liquid chromatographic determination of oxytetracycline, tetracycline, and chlortetracycline in milk.

    PubMed

    Long, A R; Hsieh, L C; Malbrough, M S; Short, C R; Barker, S A

    1990-01-01

    A multiresidue method for the isolation and liquid chromatographic determination of oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC) antibiotics in milk is presented. Blank and tetracycline (OTC, TC, and CTC) fortified milk samples (0.5 mL) were blended with octadecylsilyl (C18, 40 microns, 18% load, endcapped, 2 g) derivatized silica packing material containing 0.05 g each of oxalic acid and disodium ethylenediaminetetraacetic. A column made from the C18/milk matrix was first washed with hexane (8 mL), following which the tetracyclines were eluted with ethyl acetate-acetonitrile (1 + 3; v/v). The eluate contained tetracycline analytes that were free from interfering compounds when analyzed by liquid chromatography with UV detection (photodiode array, 365 nm). Correlation coefficients of standards curves for individual tetracycline isolated from fortified samples were linear (from 0.982 +/- 0.009 to 0.996 +/- 0.004) with average percentage recoveries from 63.5 to 93.3 for the concentration range (100, 200, 400, 800, 1600, and 3200 ng/mL) examined. The inter-assay variability ranged from 8.5 +/- 2.4% to 20.7 +/- 13.0% with an intra-assay variability of 1.0-9.3%. PMID:2115861

  18. Accessing topological order in fractionalized liquids with gapped edges

    NASA Astrophysics Data System (ADS)

    Iadecola, Thomas; Neupert, Titus; Chamon, Claudio; Mudry, Christopher

    2015-03-01

    We consider manifestations of topological order in time-reversal-symmetric fractional topological liquids (TRS-FTLs), defined on planar surfaces with holes. We derive a formula for the topological ground state degeneracy of such a TRS-FTL, which applies to cases where the edge modes on each boundary are fully gapped by appropriate backscattering terms. The degeneracy is exact in the limit of infinite system size, and is given by qNh, where Nh is the number of holes and q is an integer that is determined by the topological field theory. When the degeneracy is lifted by finite-size effects, the holes realize a system of Nh coupled spin-like q-state degrees of freedom. In particular, we provide examples where Zqquantum clock models are realized on the low-energy manifold of states. We also investigate the possibility of measuring the topological ground state degeneracy with calorimetry.

  19. Liquid chromatographic analysis of coal surface properties. Quarterly progress report, January--March 1992

    SciTech Connect

    Kwon, K.C.

    1992-04-07

    The main objectives of this proposed research work are to refine further the inverse liquid chromatography technique for the study of surface properties of raw coals, treated coals and coal minerals in water, to evaluate relatively surface properties of raw coals, treated coals and coal minerals by inverse liquid chromatography, and to evaluate flotability of various treated coals in conjunction with surface properties of coals. Coals such as Pittsburgh seam coal, Illinois No. 6 coal, Wyodak coal are chosen as representatives of high-rank bituminous coal, high volatile bituminous coal and subbituminous coal, respectively. Coal minerals such as pyrite and dolomite are chosen as representative coal minerals.

  20. High Speed Liquid Chromatographic Determination of Total Aromatics in Enamel and Lacquer Solvents.

    ERIC Educational Resources Information Center

    Esposito, G. G.

    Aromatic solvents possess the strongest solvency of the hydrogen types, but various air pollution control districts have established maximum limits on the amount that may be present in organic coatings. In the proposed procedure, high efficiency liquid chromatography is used to determine total aromatics in enamels and lacquer thinners, their…

  1. Matrix solid-phase dispersion for the liquid chromatographic determination of phenolic acids in Melissa officinalis.

    PubMed

    Ziaková, Alica; Brandsteterová, Eva; Blahová, Eva

    2003-01-01

    Matrix solid-phase dispersion (MSPD) was used for sample preparation of plant material (Melissa officinalis, Lemon Balm) prior to liquid chromatography of rosmarinic, caffeic and protocatechuic acids, phenolic compounds present in this herb. Different MSPD sorbents and various elution agents were tested and the optimal extraction conditions determined with the aim to obtain extraction recoveries greater than 90% for all analytes. PMID:12568390

  2. Acetone as a greener alternative to acetonitrile in liquid chromatographic fingerprinting.

    PubMed

    Funari, Cristiano Soleo; Carneiro, Renato Lajarim; Khandagale, Manish M; Cavalheiro, Alberto José; Hilder, Emily F

    2015-05-01

    A considerable amount of chemical waste from liquid chromatography analysis is generated worldwide. Acetonitrile is the most employed solvent in liquid chromatography analyses since it exhibits favorable physicochemical properties for separation and detection, but it is an unwelcome solvent from an environmental point of view. Acetone might be a much greener alternative to replace acetonitrile in reversed-phase liquid chromatography, since both share similar physicochemical properties, but its applicability with ultraviolet absorbance-based detectors is limited. In this work, a reference method using acetonitrile and high-performance liquid chromatography coupled to an ultraviolet photodiode array detector coupled to a corona charged aerosol detector system was developed to fingerprint a complex sample. The possibility of effectively substituting acetonitrile with acetone was investigated. Design of experiments was adopted to maximize the number of peaks acquired in both fingerprint developments. The methods with acetonitrile or acetone were successfully optimized and proved to be statistically similar when only the number of peaks or peak capacity was taken into consideration. However, the superiority of the latter was evidenced when parameters of separation and those related to greenness were heuristically combined. A green, comprehensive, time- and resource-saving approach is presented here, which is generic and applicable to other complex matrices. Furthermore, it is in line with environmental legislation and analytical trends. PMID:25708832

  3. Liquid Chromatographic Detection of Permethrin from Filter Paper Wipes of White-tailed Deer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A simple, small-scale method for the determination of the presence or absence of permethrin on the hair coat of white-tailed deer, Odocoileus virginianus (Zimmermann), by high performance liquid chromatography was developed. White-tailed deer in South Texas and the northeastern U.S. are routinely tr...

  4. Ion-pair high-performance liquid chromatographic analysis of aspartame and related products.

    PubMed

    Verzella, G; Bagnasco, G; Mangia, A

    1985-12-01

    A simple and accurate quantitative determination of aspartame (L-alpha-aspartyl-L-phenylalanine methyl ester), a new artificial sweetener, is described. The method, which is based on ion-pair high-performance liquid chromatography, allows the determination of aspartame in finished bulk and dosage forms, and the detection of a few related products at levels down to 0.1%. PMID:4086646

  5. Liquid chromatographic and spectrophotometric determination of diflucortolone valerate and isoconazole nitrate in creams.

    PubMed

    Karacan, Elif; Cağlayan, Mehmet Gokhan; Palabiyik, Ismail Murat; Onur, Feyyaz

    2011-01-01

    A new RP-LC method and two new spectrophotometric methods, principal component regression (PCR) and first derivative spectrophotometry, are proposed for simultaneous determination of diflucortolone valerate (DIF) and isoconazole nitrate (ISO) in cream formulations. An isocratic system consisting of an ACE C18 column and a mobile phase composed of methanol-water (95 + 5, v/v) was used for the optimal chromatographic separation. In PCR, the concentration data matrix was prepared by using synthetic mixtures containing these drugs in methanol-water (3 + 1, v/v). The absorbance data matrix corresponding to the concentration data matrix was obtained by measuring the absorbances at 29 wavelengths in the range of 242-298 nm for DIF and ISO in the zero-order spectra of their combinations. In first derivative spectrophotometry, dA/dlambda values were measured at 247.8 nm for DIF and at 240.2 nm for ISO in first derivative spectra of the solution of DIF and ISO in methanol-water (3 + 1, v/v). The linear ranges were 4.00-48.0 microg/mL for DIF and 50.0-400 microg/mL for ISO in the LC method, and 2.40-40.0 microg/mL for DIF and 60.0-260 microg/mL for ISO in the PCR and first derivative spectrophotometric methods. These methods were validated by analyzing synthetic mixtures. These three methods were successfully applied to two pharmaceutical cream preparations. PMID:21391489

  6. [Gas-liquid chromatographic determination of etofenamate/ Determination, method and use in biological material (author's transl)].

    PubMed

    Dell, H D; Fiedler, J; Jacobi, H; Kolle, J

    1981-01-01

    Etofenamate in biological specimen can be determined by gas-liquid chromatography with etofenamate benzyl ether as internal standard. Determination in urine is done directly after extraction and concentration, whereas plasma and homogenates from organs have to be prepurified by thin-layer chromatography. Unchanged etofenamate is found in small amounts in human urine (0--4, 6--6, 6--8 h p. appl.). Inflamed rat paws after local application contain up to 75 microgram etofenamate/g in comparison to only 2 microgram flufenamic acid/g tissue. Both compounds are also found in non-inflamed paws, contents being only 3--4% as compared to the inflamed tissue. Elimination of etofenamate from the inflamed area occurs with a half-life of approx. 8.5 h. These results from gas-liquid chromatography correspond to results from t.l.c./fluorescence measurements. PMID:6971109

  7. High-performance liquid chromatographic-amperometric determination of naloxone hydrochloride injection.

    PubMed

    Wilson, T D

    1984-08-17

    Naloxone hydrochloride has been measured in the injectable dosage form at 0.4 and 0.02 mg/ml using high-performance liquid chromatography with amperometric detection. This method was contrasted with an ultraviolet detection method at 229 nm and found to provide comparable recovery and linearity results. At the electrochemical detection limit of 0.1 ng injected a signal-to-noise ratio of 10.4 was found. PMID:6480748

  8. Development and evaluation of gas and liquid chromatographic methods for the analysis of fatty amines.

    PubMed

    Breitbach, Zachary S; Weatherly, Choyce A; Woods, Ross M; Xu, Chengdong; Vale, Glenda; Berthod, Alain; Armstrong, Daniel W

    2014-03-01

    In contrast to the plethora of publications on the separation of fatty acids, analogous studies involving fatty amines are scarce. A recently introduced ionic-liquid-based capillary column for GC was used to separate trifluoroacetylated fatty amines focusing on the analysis of a commercial sample. Using the ionic liquid column (isothermal mode at 200 °C) it was possible to separate linear primary fatty amines from C12 to C22 chain length in less 25 min with MS identification. The log of the amine retention factors are linearly related to the alkyl chain length with a methylene selectivity of 0.117 kcal/mol for the saturated amines and 0.128 kcal/mol for the mono-unsaturated amines. The sp2 selectivity for unsaturated fatty amines also could be calculated as 0.107 kcal/mol for the ionic liquid column. The commercial sample was quantified by GC with flame ionization detection (FID). An LC method also was developed with a reversed phase gradient separation using acetonitrile/formate buffer mobile phases and ESI-MS detection. Native amines could be detected and identified by their single ion monitoring chromatograms even when partial coelution was observed. The analysis of the commercial sample returned results coherent with those obtained by GC-FID and with the manufacturer's data. PMID:24415651

  9. High performance liquid chromatographic method fo pyrantel tartrate in swine feeds and supplements.

    PubMed

    Goras, J T

    1981-11-01

    A new method for the determination of pyrantel tartrate in swine feed an supplements has been developed because the current official AOAC method is not applicable to feeds co-medicated with tylosin. The new method involves: (a) leaching of drug from feed with methanolic NaCl solution, (b) removal of interfering substances by ion pair liquid-liquid extraction and high performance liquid chromatography, and (c) quantitation of pyrantel tartrate by monitoring the ultraviolet absorption of the effluent stream at 313nm. The method of standard addition is used to compensate for the effect of the feed matrix on drug recovery. No interference is encountered from tylosin, carbadox, lincomycin, non-drug components of feeds and supplements, or potential degradation products of pyrantel tartrate, i.e., cis isomer of pyrantel tartrate and (E)-N-(3-methylaminopropyl)-2-thiopheneacrylamide. Results for the assay of 3 lots each of feeds and supplements containing 0.0106 and 0.106% pyrantel tartrate, respectively, were within +/-4% of label claim. Coefficients of variation ranged from 1.6 to 1.8% for feeds and from 1.9 to 3.9% for supplements. PMID:7309651

  10. [Transfer possibilities of the mobile phases between different liquid chromatographic techniques for the analysis and isolation of compounds of biological matrices].

    PubMed

    Nyiredy, S

    1999-01-01

    After the survey and characterisation of the solid/liquid chromatographic methods, the author summarized the features of overpressure layer chromatography; the disturbing zone and the multi-front effect as well as the elimination of their influence. In light of these effects, the strategy of the mobile phase transfer possibilities is demonstrated between the various analytical and preparative liquid chromatographic methods, with the OPLC playing a central role. The main point of this strategy is that the examination of biological matrices is always begun with unsaturated TLC chamber, in which the compounds to be separated are placed between the Rf values of 0.3 and 0.8. The optimized TLC mobile phase is transferred without changes to the OPLC technique where a prerun is applied. For separation of nonpolar compounds, the prerun can be performed with hexane; for separation of polar substances the prerun can be performed with any component of the mobile phase in which the components are unable to migrate. The selection of this solvent might be considered during optimization of the mobile phase. Using HPTLC chromatoplate and analytical OPLC technique, highly effective separation can be achieved. The scaling-up for the various preparative chromatographic systems can be performed on basis of the applied chromatographic circumstances. The dry-filled preparative (FC, LPLC, MPLC) columns can be equilibrated with the solvent used for the prerun in analytical OPLC, while in case of filling with slurry technique, the slurry has to be prepared using the same solvent as was used for the prerun of OPLC. The air bubbles can be eliminated in both cases by pumping over the appropriate quantity of the solvent used for prerun, afterwards the preparative separation can be started with the optimized unsaturated TLC mobile phase. The author deals separately with the mobile phase transfer possibilities between the different analytical and preparative planar (OPLC and RPC with various

  11. An Interactive Computer Program for Simulating the Effects of Olivine Fractionation from Basaltic and Ultrabasic Liquids.

    ERIC Educational Resources Information Center

    Pearce, Thomas H.

    1983-01-01

    Describes interactive computer program (listing available from author) which simulates olivine fractionation from basaltic/ultrabasic liquid. The menu-driven nature of the program (for Apple II microcomputer) allows students to select ideal Rayleigh fractionation or equilibrium crystallization. (JN)

  12. Gas-liquid chromatographic determination of 3-trifluoromethyl-4-nitrophenol in natural waters.

    PubMed

    Coburn, J A; Chau, A S

    1976-07-01

    A procedure for the analysis of 3-trifluoromethyl-4-nitrophenol (TFM) in natural waters is described. The lampricide is extracted from acidified water samples on the macroreticular resin XAD-7 and eluted from the column with ethyl ether. The ether extract is dried, concentrated, and partitioned with potassium carbonate. TFM is acetylated in the aqueous alkaline solution and the acetate derivative is extracted into benzene for analysis by electron capture gas-liquid chromatography. Recoveries of TFM from natural waters exceeded 90% and as little as 0.01 mug TFM can be quantitated in a 1 L sample. PMID:939751

  13. Capillary liquid chromatographic fingerprint used for discrimination of Zingiber montanum from related species.

    PubMed

    Rafi, Mohamad; Lim, Lee Wah; Takeuchi, Toyohide; Darusman, Latifah Kosim

    2013-08-01

    Fingerprint analysis using capillary liquid chromatography (CLC) has been developed for discrimination of Zingiber montanum (ZM) from related species, for example Z. americans (ZA) and Z. zerumbet (ZZ). By comparing the fingerprint chromatograms of ZM, ZA, and ZZ we could identify ZM samples and discriminate them from ZA and ZZ by using their marker peaks. We also combined CLC fingerprint with multivariate analysis, including principal-component analysis (PCA) and canonical variate analysis (CVA); all three species were discriminated successfully. This result indicates that CLC fingerprint analysis in combination with PCA and CVA can be used for discrimination of ZM samples from samples of related species. PMID:23760136

  14. 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.

  15. Gas-liquid chromatographic determination of 3-trifluoromethyl-4-nitrophenol residues in fish

    USGS Publications Warehouse

    Allen, J.L.; Sills, J.B.

    1974-01-01

    A procedure for the determination of 3-mftuormethyl-4-nitrophenol (TFM) in fish tissues is described. Homogenized tissues are extracted with hexane-ethyl ether; the extract is cleaned up by partitioning the TFM from the extracting solvent into O.IN NaOB, acidifying the aqueous solution, and partitioning again with hexaneethyl ether. The TFM is methylated with diazomethane and analyzed by gas-liquid chromatography, using electron capture detection. Recoveries ranged from 75 to 1000/., from fish muscles that were spiked with 0.01-2.00 JA#g TFM/g.

  16. High-Performance Liquid Chromatographic Determination of Rivastigmine in Human Plasma for Application in Pharmacokinetic Studies

    PubMed Central

    Amini, Hossein; Ahmadiani, Abolhassan

    2010-01-01

    A simple and reproducible HPLC method with spectrophotometric detection was developed for determination of rivastigmine in human plasma. Liquid-liquid extraction of rivastigmine and donepezil (as internal standard) from plasma samples was performed with 1-butanol/n-hexane (2:98 v/v) in alkaline condition followed by back-extraction into diluted acetic acid. Chromatography was carried out using a Silica column (250 mm × 4.6 mm, 5 μm) under isocratic elution with acetonitrile-50 mM aqueous sodium dihydrogen phosphate (17: 83 v/v, pH 3.1. Analyses were run at a flow-rate of 1.3 mL/min at of 50°C. The recovery was 90.8% and 95.7% for rivastigmine and the internal standard donepezil, respectively. The precision of the method was 2.6% to 9.1% over the concentration range of 0.5-16 ng/mL for rivastigmine in plasma with a linearity greater than 0.999. The method was specific and sensitive, with a quantification limit of 0.5 ng/mL and a detection limit of 0.2 ng/mL in plasma. The method was used for a bioequivalence study in healthy subjects. PMID:24363716

  17. Comparison of ultraviolet detection and charged aerosol detection methods for liquid-chromatographic determination of protoescigenin.

    PubMed

    Filip, Katarzyna; Grynkiewicz, Grzegorz; Gruza, Mariusz; Jatczak, Kamil; Zagrodzki, Bogdan

    2014-01-01

    Escin, a complex mixture of pentacyclic triterpene saponins obtained from horse chestnut seeds extract (HCSE; Aesculus hippocastanum L.), constitutes a traditional herbal active substance of preparations (drugs) used for a treatment of chronic venous insufficiency and capillary blood vessel leakage. A new approach to exploitation of pharmacological potential of this saponin complex has been recently proposed, in which the β-escin mixture is perceived as a source of a hitherto unavailable raw material, pentacyclic triterpene aglycone-protoescigenin. Although many liquid chromatography methods are described in the literature for saponins determination, analysis of protoescigenin is barely mentioned. In this work, a new ultra-high performance liquid chromatography (UHPLC) method developed for protoescigenin quantification has been described. CAD (charged aerosol detection), as a relatively new detection method based on aerosol charging, has been applied in this method as an alternative to ultraviolet (UV) detection. The influence of individual parameters on CAD response and sensitivity was studied. The detection was performed using CAD and UV (200 nm) simultaneously and the results were compared with reference to linearity, accuracy, precision and limit of detection. PMID:25745765

  18. Chromatographic determination of biogenic amines in wines after treatment with ionic liquids as novel media.

    PubMed

    Jiang, Hai-Liang; Ying, Li-Yan; Zhou, Sai-Chun; Ying, Min; Shen, Wei; Qiu, Dong-He

    2011-05-01

    Room temperature ionic liquids (RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4) MIM][PF(6) ]), were used as the novel media for derivatization, extraction and preconcentration of biogenic amines (BAs) in wines. Six BAs, tryptamine (Try), phenylethylamine (Phe), putrescine (Put), cadaverine (Cad), tyramine (Tyr) and spermine (Spe) were selected as the model compounds and dansyl chloride (Dns-Cl) as the derivatizing reagent. The derivatizations of amines were conducted in water-IL two-phase system, in which the partition property of related substance in the IL was investigated and the mechanism (http://www.iciba.com/mechanism/) of derivation and extraction of amines was discussed. The influencing factors, including sample volume, derivatizing reagent concentration, pH value and ultrasound reaction time, were optimized. The Dns-amines were separated by high-performance liquid chromatography (HPLC), and detected with UVD at 254 nm. For each of the tested amines, a good linearity was obtained in the concentration range of 0.1-20 mg/L with the correlation coefficient (R) of 0.9814-0.9930. The limits of detection reached μg/L level and the relative standard deviations (RSD, n=3) were between 3.2 and 8.1%. Satisfactory recovery for each BA was obtained, ranging from 82.3 to 114.0%. The developed method was successfully applied to determine six BAs in red wines and Chinese yellow wine. PMID:21416603

  19. Ultra-performance liquid chromatographic determination of L-ergothioneine in commercially available classes of cow milk.

    PubMed

    Sotgia, Salvatore; Pisanu, Elisabetta; Cambedda, Debora; Pintus, Gianfranco; Carru, Ciriaco; Zinellu, Angelo

    2014-09-01

    A new efficient and sensitive precolumn hydrophilic interaction ultra-performance liquid chromatography (HILIC-UPLC) method was established for the quantitative determination of L-ergothioneine (ERT) in milk. After derivatization of ERT with 7-diethylamino-3-[4-(iodoacetamido)phenyl]-4-methylcoumarin, chromatographic separation was achieved in a fairly short time, less than 5 min, on a 100 × 2.1 mm Waters Cortecs UPLC HILIC 1.6-μm column, by using a mixture of 30 mmol/L ammonium acetate/acetonitrile (10:90, v/v) as a mobile phase flowing isocratically at 0.9 mL/min. Limit of detection and the limit of quantification were 0.03 and 0.10 μmol/L, respectively. The method exhibited linearity in a concentration range of 0.16 and 5.08 μmol/L. Mean recovery was 106.66%, whereas intra- and interassay precisions were determined to be within 6 RSD%. On average, ERT concentration in different commercially available classes of cow milk was found to be 0.442 ± 0.191 μmol/L, with the highest levels in the ultra-high temperature milks and low values in the unprocessed and HTST whole milks. In this light, our experiments suggest that ERT could be used as a marker for the heat treatment of milk. PMID:25154712

  20. Sensitive and convenient high-performance liquid chromatographic method for the determination of mitomycin C in human plasma.

    PubMed

    Joseph, G; Biederbick, W; Woschée, U; Theisohn, M; Klaus, W

    1997-09-26

    An improved high-performance liquid chromatographic assay for the cytostatic drug mitomycin C in plasma is presented. The principal steps are precipitation of plasma proteins with acetonitrile, lyophilization of the supernatant and reversed-phase chromatography on a Hypersil ODS 5 microm column with 0.01 M NaH2PO4 buffer (pH 6.5)-methanol (70:30, v/v) in isocratic mode. At a flow-rate of 1.3 ml/min a column pressure of 180-220 bar resulted. Porfiromycin served as internal standard. UV detection was performed at 365 nm. Quantitation limit based on a coefficient of variation <10% in intra- and inter-day assay was 5 microg/l mitomycin C, detection limit based on a signal-to-noise ratio of 3 was 1 microg/l. Recovery was 100% and linearity was shown for the whole range of concentration (1-500 microg/l). None of the five drugs used during chemoembolisation interfered with the assay in vitro. The assay meets the requirements for pharmacokinetic studies of mitomycin C in patients as regards sensitivity and ease of use. PMID:9367216

  1. High-performance liquid chromatographic assay for the simultaneous determination of ipratropium bromide, fenoterol, salbutamol and terbutaline in nebulizer solution.

    PubMed

    Jacobson, G A; Peterson, G M

    1994-06-01

    A reversed-phase ion-pair high-performance liquid chromatography assay was developed for the simultaneous determination of ipratropium bromide, fenoterol hydrobromide, salbutamol sulphate and terbutaline sulphate in nebulizer solution. Chromatographic separation was achieved with a Nova-Pak C18 4 microns 10 cm x 8 mm i.d. Radial-pak cartridge inside a Waters RCM 8 x 10 compression module using ternary gradient analysis. Detection was performed using UV detection at 220 nm. The standard curves were linear over the following ranges: ipratropium bromide 20.8-250.0 micrograms ml-1, fenoterol hydrobromide 27.8-500.0 micrograms ml-1, salbutamol sulphate 34.7-2500.0 micrograms ml-1 and terbutaline sulphate 69.5-2500 micrograms ml-1. Inter-day and intra-day relative standard deviations for each compound ranged from 4.5-5.2% and 3.5-3.9%, respectively. The assay procedure was developed to allow the accurate determination of constituents in various combinations of nebulizer solution, as well as for stability indicating purposes. This provides a convenient means of testing long-term compatibility and stability following the post-manufacture mixing of commonly used nebulized preparations. PMID:7918785

  2. Chromatographic performance of synthetic polycrystalline diamond as a stationary phase in normal phase high performance liquid chromatography.

    PubMed

    Peristyy, Anton; Paull, Brett; Nesterenko, Pavel N

    2015-04-24

    The chromatographic properties of high pressure high temperature synthesised diamond (HPHT) are investigated in normal phase mode of high performance liquid chromatography. Purified nonporous irregular shape particles of average particles size 1.2 μm and specific surface area 5.1 m(2) g(-1) were used for packing 100×4.6 mm ID or 50×4.6 mm ID stainless steel columns. The retention behaviour of several classes of compounds including alkyl benzenes, polyaromatic hydrocarbons (PAH), alkylphenylketones, phenols, aromatic acids and bases were studied using n-hexane-2-propanol mixtures as mobile phase. The results are compared with those observed for microdispersed sintered detonation nanodiamond (MSDN) and porous graphitic carbon (PGC). HPHT diamond revealed distinctive separation selectivity, which is orthogonal to that observed for porous graphitic carbon; while selectivities of HPHT diamond and microdispersed sintered detonation nanodiamonds are similar. Owing to non-porous particle nature, columns packed with high pressure high temperature diamond exhibited excellent mass transfer and produce separations with maximum column efficiency of 128,200 theoretical plates per meter. PMID:25777051

  3. Combined column-mobile phase mixture statistical design optimization of high-performance liquid chromatographic analysis of multicomponent systems.

    PubMed

    Breitkreitz, Márcia C; Jardim, Isabel C S F; Bruns, Roy E

    2009-02-27

    A statistical approach for the simultaneous optimization of the mobile and stationary phases used in reversed-phase liquid chromatography is presented. Mixture designs using aqueous mixtures of acetonitrile (ACN), methanol (MeOH) and tetrahydrofuran (THF) organic modifiers were performed simultaneously with column type optimization, according to a split-plot design, to achieve the best separation of compounds in two sample sets: one containing 10 neutral compounds with similar retention factors and another containing 11 pesticides. Combined models were obtained by multiplying a linear model for column type, C8 or C18, by quadratic or special cubic mixture models. Instead of using an objective response function, combined models were built for elementary chromatographic criteria (retention factors, resolution and relative retention) of each solute or pair of solutes and, after their validation, the global separation was accomplished by means of Derringer's desirability functions. For neutral compounds a 37:12:8:43 (v/v/v/v) percentage mixture of ACN:MeOH:THF:H2O with the C18 column and for pesticides a 15:15:70 (v/v/v) ACN:THF:H2O mixture with the C8 column provide excellent resolution of all peaks. PMID:19167715

  4. Ion-pair ultra-high performance liquid chromatographic analysis of monoamines: peak-splitting at high flow rates.

    PubMed

    Van Schoors, Jolien; Brouwer, Hendrik-Jan; Maes, Katrien; Michotte, Yvette; Van Eeckhaut, Ann

    2013-12-20

    The use of ion-pair ultra-high performance liquid chromatography (UHPLC) coupled with electrochemical detection (ECD) is of great interest for the fast and sensitive determination of the monoamine neurotransmitters dopamine, noradrenaline and serotonin in microdialysis samples. However, when applying high flow rates in ion-pair UHPLC, other peaks than the initial compound peaks appear on the chromatogram. This peak-splitting phenomenon is caused by disturbed ion-pair retention mechanisms. The influence of several chromatographic parameters is investigated. Peak-splitting is delayed to higher flow rates when increasing the concentration of ion-pair reagent or buffering agent in the mobile phase, when decreasing the percentage of organic modifier in the mobile phase, when applying a stationary phase with a smaller amount of packing material or when increasing the separation temperature. One or a combination of these conditions can be applied to analyze the monoamine neurotransmitters using ion-pair UHPLC-ECD at high flow rates. PMID:24238712

  5. Development and Validation of Stability-indicating High Performance Liquid Chromatographic Method for the Estimation of Everolimus in Tablets

    PubMed Central

    Sharmila, D.; Rao, A. Lakshmana; Kalyani, L.

    2015-01-01

    The present study depicts the development of a validated reversed-phase high performance liquid chromatographic method for the determination of the everolimus in presence of degradation products or pharmaceutical excipients. Stress study was performed on everolimus and it was found that it degrade sufficiently in oxidizing and acidic conditions but less degradation was found in alkaline, neutral, thermal and photolytic conditions. The separation was carried out on Hypersil BDS C18 column (100×4.6 mm, 5 μ) column having particle size 5 μ using acetate buffer:acetonitrile (50:50 v/v) with pH 6.5 adjusted with orthophosphoric acid as mobile phase at flow rate of 1 ml/min. The wavelength of the detection was 280 nm. A retention time (Rt) nearly 3.110 min was observed. The calibration curve for everolimus was linear (r2=0.999) from range of 25-150 μg/ml with limit of detection and limit of quantification of 0.036 μg/ml and 0.109 μg/ml, respectively. Analytical validation parameters such as selectivity, specificity, linearity, accuracy and precision were evaluated and relative standard deviation value for all the key parameters were less than 2.0%. The recovery of the drug after standard addition was found to be 100.55%. Thus, the developed RP-HPLC method was found to be suitable for the determination of everolimus in tablets containing various excipients. PMID:26798176

  6. Development of a high-performance-liquid-chromatographic method for the determination of biapigenin in biorelevant media.

    PubMed

    Schulte-Löbbert, S; Westerhoff, K; Wilke, A; Schubert-Zsilavecz, M; Wurglics, M

    2003-09-15

    A new precise, rapid and selective high-performance-liquid-chromatographic (HPLC) method has been developed to quantify biapigenin in St. John's Wort (SJW) preparations and to investigate its release characteristics in the dissolution test using both compendial and biorelevant media. Experiments were carried out on a LiChroCart 125-4, RP-18 (5 microm) column, using gradient elution at a flow rate of 1 ml/min. The binary mobile phase consisted of solvent A (acetic acid, 5:100, w:w) and B (a mixture of acetonitrile and methanol (3:1, v:v)). Detection was performed at a wavelength of 270 nm using a photodiodearray detector. The limit of detection was 0.05 microg/ml, the injection volume 20 microl. Five SJW preparations were chosen to determine the amount of biapigenin in the dosage form and to investigate their release characteristics. Best results in terms of release as well as discriminating the tested products were obtained, using fed state simulated intestinal fluid (FeSSIF), where over 80% of biapigenin was dissolved after 20 min comparing to 70% using simulated gastric fluid sine pepsin (SGF(sp)) as compendial medium. Experiments in fasted state simulated intestinal fluid (FaSSIF) show 80% release of biapigenin within 80 min. PMID:12946531

  7. Triazolines. XXIII. High-performance liquid chromatographic assay in rat blood for a novel triazoline anticonvulsant (ADD17014).

    PubMed

    Stevenson, P J; Hamelijnck, M A; Kadaba, P K; Damani, L A

    1991-02-15

    A sensitive and specific high-performance liquid chromatographic (HPLC) method for the analysis of 1-(4-chlorophenyl)-5-(4-pyridyl)-delta 2-1,2,3-triazoline (ADD17014, I), a novel anticonvulsant agent, in rat blood is described. Compound I and the internal standard (dipyridamole) were extracted into diethyl ether (5 ml) from alkalinised blood (0.25 ml of blood plus 0.75 ml of pH 10.7 buffer), with extractability nearing 100% under these conditions. The assay is based on reversed-phase HPLC (25 cm x 0.46 cm I.D. Spherisorb 5-ODS) using a mobile phase of methanol-acetonitrile-McIlvaine's citric acid-phosphate buffer (pH 8.0, 0.005 M) (30:30:40, v/v) and ultraviolet detection at 290 nm. Calibration curves were linear and reproducible (correlation coefficient greater than 0.999). Measurement of I in rat blood (250 microliters sample size) was linear in the range 0-40 microgram/ml and the coefficient of variation was less than 5%. The minimum detectable level was about 0.1 microgram/ml; however, a larger blood sample size (1-2 ml) allowed measurement of levels as low as 10 ng/ml, especially for estimation of drug levels in samples withdrawn at later time points (24 h). PMID:2056006

  8. Validation and application of a liquid-chromatographic/enzymatic assay for individual bile acids in the serum of rats.

    PubMed

    Thompson, M B; Blair, P C; Morris, R W; Neptun, D A; Deyo, D F; Popp, J A

    1987-10-01

    A liquid-chromatographic technique with a post-column enzymatic reaction and fluorescence detection was validated for analysis of individual bile acids in the serum of rats. Extraction recoveries averaged 91.1% (SD 6.9%) for all bile acids. The assay was sensitive (minimum detection of 16.8 pmol per 100-microL injection), linear (r greater than 0.999 for concentrations ranging between 45 and 112,500 pmol per 100-microL injection), and reproducible (mean CVs for three different concentrations of standards and a serum pool ranged from 4.4% to 12.2%). In rats treated for three days with either neomycin, carbon tetrachloride, alpha-naphthylisothiocyanate, or total bile-duct ligation (five animals per group), total concentrations of bile acids were significantly increased (P less than 0.004). Concentrations of 16 of 17 individual bile acids differed significantly between groups (P less than 0.04). Examination of the relative concentrations (percent of total) of individual bile acids by canonical discriminant analysis placed each animal into the appropriate treatment or control group. Use of this technique in toxicological studies can help detect and identify specific types of disruptions in the enterohepatic circulation of bile acids. PMID:3665040

  9. Development and validation of a reversed phase liquid chromatographic method for analysis of oxytetracycline and related impurities.

    PubMed

    Kahsay, Getu; Shraim, Fairouz; Villatte, Philippe; Rotger, Jacques; Cassus-Coussère, Céline; Van Schepdael, Ann; Hoogmartens, Jos; Adams, Erwin

    2013-03-01

    A simple, robust and fast high-performance liquid chromatographic method is described for the analysis of oxytetracycline and its related impurities. The principal peak and impurities are all baseline separated in 20 min using an Inertsil C₈ (150 mm × 4.6 mm, 5 μm) column kept at 50 °C. The mobile phase consists of a gradient mixture of mobile phases A (0.05% trifluoroacetic acid in water) and B (acetonitrile-methanol-tetrahydrofuran, 80:15:5, v/v/v) pumped at a flow rate of 1.3 ml/min. UV detection was performed at 254 nm. The developed method was validated for its robustness, sensitivity, precision and linearity in the range from limit of quantification (LOQ) to 120%. The limits of detection (LOD) and LOQ were found to be 0.08 μg/ml and 0.32 μg/ml, respectively. This method allows the separation of oxytetracycline from all known and 5 unknown impurities, which is better than previously reported in the literature. Moreover, the simple mobile phase composition devoid of non-volatile buffers made the method suitable to interface with mass spectrometry for further characterization of unknown impurities. The developed method has been applied for determination of related substances in oxytetracycline bulk samples available from four manufacturers. The validation results demonstrate that the method is reliable for quantification of oxytetracycline and its impurities. PMID:23277151

  10. Liquid chromatographic determination of chloramine-T and its primary degradation product, p-toluenesulfonamide, in water

    USGS Publications Warehouse

    Dawson, Verdel K.; Davis, Ruth A.

    1997-01-01

    N-sodium-N-chloro-rho-toluenesulfonamide (chloramine-T) effectively controls bacterial gill disease (BGD) in cultured fishes, BGD, a common disease of hatchery-reared salmonids, causes more fish losses than any other disease among these species. This study describes a liquid chromatographic (LC) method that is capable of direct, simultaneous analysis of chloramine-T and its primary degradation product, rho-toluenesulfonamide (rho-TSA), in water. The procedure involves reversed-phase (C-18) LC analysis with ion suppression, using 0.01 M phosphate buffer at pH 3. The mobile phase is phosphate buffer-acetonitrile (60 + 40) at 1 mL/min. Both chemicals can be detected with a UV spectrophotometer at 229 nm; the method is linear up to 40 mg, chloramine-T or rho-TSA/L. Mean recoveries were 96.4 +/- 6.1% for water samples fortified with 0.03 mg chloramine-T/L and 95.3 +/- 4.6% for water samples fortified with 0.005 mg rho-TSA/L. Limits of detection without sample enrichment for chloramine-T and rho-TSA are 0.01 mg/L and 0.001 mg/L, respectively.

  11. Liquid chromatographic determination of chloramine-T and its primary degradation product, p-toluenesulfonamide, in water

    USGS Publications Warehouse

    Dawson, V.K.; Davis, R.A.

    1997-01-01

    N-sodium-N-chloro-rho-toluenesulfonamide (chloramine-T) effectively controls bacterial gill disease (BGD) in cultured fishes, BGD, a common disease of hatchery-reared salmonids, causes more fish losses than any other disease among these species, This study describes a liquid chromatographic (LC) method that is capable of direct, simultaneous analysis of chloramine-T and its primary degradation product, rho-toluenesulfonamide (rho-TSA), in water. The procedure involves reversed-phase (C-18) LC analysis with ion suppression, using 0.01 M phosphate buffer at pH 3. The mobile phase is phosphate buffer-acetonitrile (60 + 40) at 1 mL/min. Both chemicals can be detected with a UV spectrophotometer at 229 nm; the method is linear up to 40 mg, chloramine-T or rho-TSA/L. Mean recoveries were 96.4 +/- 6.1% for water samples fortified with 0.03 mg chloramine-T/L and 95.3 +/- 4.6% for water samples fortified with 0.005 mg rho-TSA/L. Limits of detection without sample enrichment for chloramine-T and rho-TSA are 0.01 mg/L and 0.001 mg/L, respectively.

  12. Comparison of three liquid chromatographic methods with FDA optimized Monier-Williams method for determination of total sulfite in foods.

    PubMed

    Lawrence, J F; Chadha, R K; Ménard, C

    1990-01-01

    Three liquid chromatographic (LC) methods employing amperometric detection were compared with the collaboratively studied FDA optimized Monier-Williams distillation method for the determination of total sulfite in 5 food types. The foods included lemon juice, white wine, instant mashed potatoes, golden raisins, and onion flakes. Two of the LC methods (one employing headspace sampling and the other direct injection) used ion-exchange chromatography with a basic mobile phase (pH about 10.8) and a glassy carbon electrode; the third (employing direct injection) used ion-exclusion chromatography with an acidic mobile phase (pH about 2) and a platinum electrode. All 4 methods produced similar results for the wine, lemon juice, and raisins. Results were different for instant mashed potatoes and onion flakes. The headspace-LC method and direct ion-exclusion LC method, both of which employed an alkaline sample extraction, yielded significantly higher values for sulfite in instant potatoes than did the other 2 methods. A large interfering peak with both direct LC methods prevented quantitation of sulfite in the onion flakes. All methods can detect sulfite as low as about 1 microgram/g in 4 of 5 food types examined. PMID:2312516

  13. Development and validation of column high-performance liquid chromatographic and ultraviolet spectrophotometric methods for citalopram in tablets.

    PubMed

    Menegola, Júlia; Steppe, Martin; Schapoval, Elfrides E S

    2008-01-01

    Column high-performance liquid chromatographic (LC) and UV spectrophotometric methods for the quantitative determination of citalopram, a potent and selective serotonin reuptake inhibitor, in tablets were developed. The parameters linearity, precision, accuracy, specificity, robustness, limit of detection, and limit of quantitation were studied according to International Conference on Harmonization guidelines. Chromatography was carried out by the reversed-phase technique on an ACE C18 column with a mobile phase composed of 0.30% triethylamine solution-acetonitrile (55 + 45, v/v) adjusted to pH 6.6 with 10% ortho-phosphoric acid at a flow rate of 1.0 mL/min and 25 degrees C. The UV spectrophotometric method was performed at 239 nm. The linearity of the LC method was in the range of 10.00-70.00 microg/mL, and 2.50-17.50 microg/mL for the UV spectrophotometric method. The interday and intraday assay precision was < 1.5% (relative standard deviation) for the LC and UV spectrophotometric methods. The recoveries were in the range 100.70-101.35% for the LC method and 98.48-98.65% for the UV spectrophotometric method. Statistical analysis by Student's t-test showed no significant difference between the results obtained by the 2 methods. The proposed methods are highly sensitive, precise, and accurate and can be used for the reliable quantitation of citalopram in tablets. PMID:18376585

  14. Development and Validation of Stability-indicating High Performance Liquid Chromatographic Method for the Estimation of Everolimus in Tablets.

    PubMed

    Sharmila, D; Rao, A Lakshmana; Kalyani, L

    2015-01-01

    The present study depicts the development of a validated reversed-phase high performance liquid chromatographic method for the determination of the everolimus in presence of degradation products or pharmaceutical excipients. Stress study was performed on everolimus and it was found that it degrade sufficiently in oxidizing and acidic conditions but less degradation was found in alkaline, neutral, thermal and photolytic conditions. The separation was carried out on Hypersil BDS C18 column (100×4.6 mm, 5 μ) column having particle size 5 μ using acetate buffer:acetonitrile (50:50 v/v) with pH 6.5 adjusted with orthophosphoric acid as mobile phase at flow rate of 1 ml/min. The wavelength of the detection was 280 nm. A retention time (Rt) nearly 3.110 min was observed. The calibration curve for everolimus was linear (r(2)=0.999) from range of 25-150 μg/ml with limit of detection and limit of quantification of 0.036 μg/ml and 0.109 μg/ml, respectively. Analytical validation parameters such as selectivity, specificity, linearity, accuracy and precision were evaluated and relative standard deviation value for all the key parameters were less than 2.0%. The recovery of the drug after standard addition was found to be 100.55%. Thus, the developed RP-HPLC method was found to be suitable for the determination of everolimus in tablets containing various excipients. PMID:26798176

  15. Development and Validation of a Liquid Chromatographic Method for Estimation of Dicyclomine Hydrochloride, Mefenamic Acid and Paracetamol in Tablets

    PubMed Central

    Shah, D. A.; Rana, Jainika P.; Chhalotiya, Usmangani K.; Baldania, S. L.; Bhatt, K. K.

    2014-01-01

    Liquid chromatographic method was developed for simultaneous quantitative determination of dicyclomine hydrochloride, mefenamic acid and paracetamol in their combined dosage form. The separation was achieved using a C18 column (250×4.6 mm id, 5 μm) using acetonitrile:20 mM potassium dihydrogen phosphate 70:30 (v/v) adjusted to pH 4 using orthophosphoric acid as mobile phase at a flow rate of 1 ml/min and detection at 220 nm. Separation was completed within 12 min. The retention times of dicyclomine hydrochloride, mefenamic acid and paracetamol were 3.8, 9.3 and 2.5 minutes respectively. The proposed method was found to have linearity in concentration range of 10–100 μg/ml for dicyclomine hydrochloride, 0.05-10 μg/ml for mefenamic acid and 0.1−20 μg/ml for paracetamol. The developed method has been statistically validated and was found to be simple, precise, reproducible and accurate. The developed and validated method was successfully used for the quantitative analysis of commercially available dosage form. PMID:25593386

  16. Simultaneous quantification of related substances of perindopril tert-butylamine using a novel stability indicating liquid chromatographic method.

    PubMed

    Szabó, Zoltán-István; Réti, Zenkő-Zsuzsánna; Gagyi, László; Kis, Erika Lilla; Sipos, Emese

    2015-03-01

    A novel stability indicating gradient reverse-phased high-performance liquid chromatographic method has been developed for the quantification of impurities of perindopril tert-butylamine (PER) in pharmaceutical dosage form. Separation of the active substance and its known (Impurities B, C, D, E, F) and unknown impurities was achieved on a BDS Hypersil C18 column (250 mm × 4.6 mm, 5 µm), thermostated at 70°C, using a mobile phase comprised of aqueous solution of sodium 1-heptanesulfonate adjusted to pH 2 with perchloric acid and acetonitrile. The flow rate was maintained at 1.5 mL min(-1), injection volume of 20 µL was utilized and detection of analytes was performed at 215 nm. The developed method was validated in accordance with current ICH Guidelines for all suggested parameters, including forced degradation studies and proved to be linear, accurate, precise and suitable for the impurity testing of PER, being subsequently applied during on-going stability studies of a newly developed generic formulation. PMID:25616989

  17. Rapid reversed-phase liquid chromatographic determination of patulin in apple juice.

    PubMed

    Gökmen, V; Acar, J

    1996-04-12

    A rapid, simple and economical method using a limited amount of organic solvent is described for the determination of patulin in apple juice. The sample was extracted with ethyl acetate and the extract was cleaned up by extraction with sodium carbonate solution. Patulin was then determined by reversed-phase liquid chromatography using a MicroPack C18 column and a variable-wavelength UV-Vis detector set at 276 nm. Patulin and 5-hydroxymethylfurfural were completely resolved by using water-acetonitrile (99:1, v/v) as the mobile phase at a flow-rate of 1.0 ml/min. The detection limit was < 5 micrograms/l and the recovery was 98%. PMID:8680596

  18. Liquid chromatographic tandem mass spectrometric determination of five coccidiostats in poultry eggs and feed.

    PubMed

    Mortier, Leen; Daeseleire, Els; Van Peteghem, Carlos

    2005-06-25

    A method is described which permits the quantitative detection of the chemical coccidiostats halofuginone, robenidine, diclazuril, nicarbazin and dimetridazole and its main metabolite 2-hydroxydimetridazole in poultry eggs and feed. Sample preparations were kept very simple and are based upon extraction with an organic solvent. Sample extracts were injected into the liquid chromatography tandem mass spectrometry (LC-MS/MS) system on a C18 column and a gradient elution was performed. Dimetridazole-D3 and diclazuril-bis, a structural analogue of diclazuril, were used as internal standards. Detection was performed on a triple quadrupole mass spectrometer in the selected reaction monitoring mode after ionisation in the positive or negative electrospray ionisation mode. Argon was applied as collision gas for collision induced dissociation. Validation of the methods was performed based on Commission Decision 2002/657/EC [Official Journal of the European Communities L221 (2002) 8]. PMID:15893963

  19. Sample preparation and liquid chromatographic determination of vitamin D in food products.

    PubMed

    Bui, M H

    1987-01-01

    Vitamin D in different fortified foods is determined by using liquid chromatography (LC). Sample preparation is described for fortified skim milk, infant formulas, chocolate drink powder, and diet food. The procedure involves 2 main steps: saponification of the sample followed by extraction, and quantitation by LC analysis. Depending on the sample matrix, additional steps are necessary, i.e., enzymatic digestion for hydrolyzing the starch in the sample and cartridge purification before LC injection. An isocratic system consisting of 0.5% water in methanol (v/v) on two 5 microns ODS Hypersil, 12 X 0.4 cm id columns is used. Recovery of vitamin D added to unfortified skim milk is 98%. The results of vitamin D determination in homogenized skim milk, fortified milk powder, fortified milk powder with soybean, chocolate drink powder, and sports diet food are given. PMID:3680113

  20. A Simple, Inexpensive, High Pressure Liquid Chromatographic Method for Separating Cytokinins in Plant Extracts

    PubMed Central

    Thomas, Tudor H.; Carroll, James E.; Isenberg, Francis M. R.; Pendergrass, Ann; Howell, Lydia

    1975-01-01

    Separation of a mixture of the main cytokinins occurring naturally in plant tissues was achieved by high pressure liquid chromatography using insoluble polyvinylpyrrolidone as the solid support. The separation of each cytokinin was first assessed over a range of salt and l-butanol concentrations and pH using a mixture of borate buffer and l-butanol as the mobile phase to determine the conditions necessary for optimum resolution. A discrete separation of zeatin, N-6-(Δ-2-isopentenyl)adenine, their related ribonucleosides, and kinetin was achieved using a simple isocratic elution with 0.025 m borate buffer at pH 6.8 and 4% (v/v) l-butanol. A number of cytokinin-active compounds were detected in cabbage extracts by the Amaranthus betacyanin bioassay using this separation technique. PMID:16659314

  1. Liquid chromatographic determination of sugar alcohols in beverages and foods after nitrobenzoylation.

    PubMed

    Nojiri, S; Saito, K; Taguchi, N; Oishi, M; Maki, T

    1999-01-01

    Use of p-nitrobenzoyl chloride (PNBC) to form an ultraviolet-absorbing derivative was attempted to determine the sugar alcohols meso-erythritol, xylitol, D-sorbitol, and D-mannitol by liquid chromatography (LC). LC determination of derivatives was performed on an ODS column with acetonitrile-water (65 + 35) as mobile phase. Calibration curves were linear in the concentration range 0.01-100 micrograms/mL. Method sensitivity is 10 to 1000 times higher than that of LC with refractive index detection and gas chromatography with flame ionization detection. Recoveries of sugars added to various foods at 0.1 and 1% ranged from 91 to 102% for meso-erythritol, 75 to 115% for xylitol, 81 to 105% for D-sorbitol, and 81 to 108% for D-mannitol. PMID:10028682

  2. High-performance liquid chromatographic assay for the determination of Aloe Emodin in mouse plasma.

    PubMed

    Zaffaroni, M; Mucignat, C; Pecere, T; Zagotto, G; Frapolli, R; D'Incalci, M; Zucchetti, M

    2003-10-25

    An isocratic high-performance liquid chromatography (HPLC) method was developed and validated to determine Aloe Emodin (AE) in mouse plasma. The analysis required 0.3 ml of plasma and involves extraction with dichloromethane. The HPLC separation was carried out on Symmetry Shield RP18, a mobile phase of methanol-water-acetic acid (65:35:0.2) and fluorescence detection at lambda(ex)=410 nm and lambda(em)=510 nm. The retention time of AE was 11.7 min. The assay was linear from 10 to 1,000 ng/ml (r2 > or = 0.999), showed intra- and inter-day precision within 7.8 and 4.7%, and accuracy of 87.3-105.7%. Detection limit (LOD) and quantification limit (LOQ) were 4.5 and 5 ng/ml, respectively. The method was applied to determine for the first time the pharmacokinetic of AE in mice. PMID:14552822

  3. Gas-liquid chromatographic determination of kepone in field-collected avian tissues and eggs

    USGS Publications Warehouse

    Stafford, C.J.; Reichel, W.L.; Swineford, D.M.; Prouty, R.M.; Gay, M.L.

    1978-01-01

    A procedure is described for determining Kepone (decachlorooctahydro-1,3,4-metheno-2H-cyclobuta [cd] pentalene-2-one) residues in avian egg, liver, and tissue. Samples were extracted with benzene-isopropanol, and the extract was cleaned up with fuming H2SO4-concentrated H2SO4. Kepone was separated from organochlorine pesticides and polychlorinated biphenyls on a Florisil column and analyzed by electron capture gas-liquid chromatography (GLC). The average recovery from spiked tissues was 86%. The analyses performed on 14 bald eagle carcasses and livers, 3 bald eagle eggs, and 14 osprey eggs show measurable levels which indicate that Kepone accumulates in the tissues of fish-eating birds. Residues were confirmed by GLC-mass spectrometry.

  4. Simultaneous high-pressure liquid chromatographic determination of acetaminophen, guaifenesin, and dextromethorphan hydrobromide in cough syrup.

    PubMed

    McSharry, W O; Savage, I V

    1980-02-01

    Acetaminophen (I), guaifenesin (II), and dextromethorphan hydrobromide (III) were separated and quantitated simultaneously in cough syrup by high-pressure liquid chromatography. A chemically bonded octadecylsilane stationary phase was used with a mobile phase of 48% (v/v) aqueous methanol. The mobile phase pH was stabilized to 4.2 by adding formic acid--ammonium formate buffer (approximately 0.4%). The internal standard was o-dinitrobenzene. Retention volumes were 4 ml for I, 6 ml for II, 11 ml for the internal standard, and 20 ml for III. Inactive syrup components did not interfere, permitting direct diluted sample injection. Results on active ingredients were essentially 100% of the claim, with standard deviations of +/- 1.5, 1.2, and 2.1% for I, II, and III, respectively. PMID:7359328

  5. High pressure liquid chromatographic determination of carbadox and pyrantel tartrate in swine feed and supplements.

    PubMed

    Lowie, D M; Teague, R T; Quick, F E; Foster, C L

    1983-05-01

    A rapid yet reliable procedure for the simultaneous extraction and assay of carbadox and pyrantel tartrate is described. The feed is extracted with water-acetonitrile-methanol and cleaned up on a short alumina column. The eluant is separated by high pressure liquid chromatography and the compounds are detected at different wavelengths. The drugs of interest are well resolved in all feeds studied. The procedure has also been applied to a wide range of feeds which contained either one of the drugs or both in combination. No significant interferences were observed. Spiked sample recoveries were 97% for carbadox and 101% for pyrantel tartrate. Ruggedness test coefficients of variation were 2.0% for carbadox and 2.1% for pyrantel tartrate. PMID:6863181

  6. Comparison of liquid chromatographic and bioassay procedures for determining depletion of intramuscularly injected tylosin.

    PubMed

    Moats, W A; Harris, E W; Steele, N C

    1985-01-01

    Crossbred pigs weighing 80-110 kg were injected intramuscularly in the ham with 8.8 mg/kg tylosin. Animals were slaughtered in groups of 3 at intervals of 4 h, and 1, 2, 4, and 8 days after injection, and samples of blood, injected muscle, uninjected muscle, liver, and kidney were analyzed by liquid chromatography (LC) and by bioassay using Sarcina lutea as the test organism. The LC method was far more sensitive with a detection limit of less than 0.1 ppm, while the detection limit by bioassay was about 0.5 ppm in tissue. Results by bioassay and LC sometimes differed considerably for tissue samples. Residues in all tissues were below the tolerance limit of 0.2 ppm at 24 h, except in the injected muscle in one animal. Residues were not detected in any tissue of any animal at 48 h after treatment. PMID:4019360

  7. Liquid chromatographic-photodiode array mass spectrometric analysis of dietary phytoestrogens from human urine and blood.

    PubMed

    Franke, Adrian A; Custer, Laurie J; Wilkens, Lynne R; Le Marchand, Loïc Le; Nomura, Abraham M Y; Goodman, Marc T; Kolonel, Laurence N

    2002-09-25

    Dietary phytoestrogens have been implicated in the prevention of chronic diseases. However, it is uncertain whether the phytoestrogens or the foods associated with phytoestrogens account for the observed effects. We report here a new liquid chromatography photodiode array mass spectrometry (LC-PDA-MS) assay for the determination of nanomolar amounts of the most prominent dietary phytoestrogens (genistein, dihydrogenistein, daidzein, dihydrodaidzein, glycitein, O-desmethylangolensin, hesperetin, naringenin, quercetin, enterodiol, enterolactone) in human plasma or serum and urine. This assay was found to be suitable for the assessment of quercetin exposure in an onion intervention study by measuring urinary quercetin levels. Other successful applications of this assay in clinical and epidemiologic studies validated the developed method and confirmed previous results on the negative association between urinary isoflavone excretion and breast cancer risk. PMID:12270199

  8. Characterization of Gas Chromatographic Liquid Phases Using McReynolds Constants. An Experiment for Instrumental Analysis Laboratory.

    ERIC Educational Resources Information Center

    Erskine, Steven R.; And Others

    1986-01-01

    Describes a laboratory experiment that is designed to aid in the understanding of the fundamental process involved in gas chromatographic separations. Introduces the Kovats retention index system for use by chemistry students to establish criteria for the optimal selection of gas chromatographic stationary phases. (TW)

  9. Simultaneous liquid chromatographic determination of carotenoids, retinoids, and tocopherols in human buccal mucosal cells.

    PubMed

    Peng, Y S; Peng, Y M

    1992-01-01

    Epidemiological and experimental data have suggested that some micronutrients, including various carotenoids, retinoids, and alpha-tocopherol, may have chemopreventive activity against certain types of human cancer. In order to define the role of these micronutrients in cancer prevention, it is necessary to measure their concentrations in the target tissues, since these are critical to the chemopreventive effect. We have developed a sensitive and reproducible high-performance liquid chromatography procedure for the simultaneous determination of lutein, zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, beta-carotene, cis-beta-carotene, retinol, retinyl palmitate, alpha-tocopherol, and gamma-tocopherol in an easily accessible human target tissue, the buccal mucosal cells. This procedure used a gradient of two mobile phases which consisted of acetonitrile, tetrahydrofuran, methanol, 1% ammonium acetate, and butylated hydroxytoluene (in v/v/v/v/w): mobile phase A, 85:5:5:5:0.05; mobile phase B, 55:35:5:5:0.05. The run time, including reequilibration, was 47 min: from 100% A to 100% B in 27 min, remaining at that mobile phase for 10 min, then back to 100% A at 43 min at a constant flow rate of 1.3 ml/min. The high-performance liquid chromatography effluent was monitored at 300, 325, and 452 nm for tocopherols, retinoids, and carotenoids, respectively, with a photodiode array detector. The average recovery was 83% for lycopene and > 92% for others. The precision of the assay for all the compounds was less than 10% in a 1-month period. The micronutrients were extracted by incubating the cells with protease, followed by vortex mixing with 1% sodium dodecyl sulfate in ethanol containing 0.1% butylated hydroxytoluene, and, finally, hexane extraction.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1305470

  10. High-performance liquid chromatographic assay for 4-nitrophenol hydroxylation, a putative cytochrome P-4502E1 activity, in human liver microsomes.

    PubMed

    Tassaneeyakul, W; Veronese, M E; Birkett, D J; Miners, J O

    1993-06-23

    A high-performance liquid chromatographic method which measures formation of product 4-nitrocatechol (4NC) has been developed and applied to the study of human liver microsomal 4-nitrophenol (4NP) hydroxylation. Following diethyl ether extraction, 4NC and the assay internal standard (salicylamide) were separated by reversed-phase (C18) liquid chromatography. Extraction efficiencies of 4NC and internal standard were both > 90%. The assay, which has a limit of detection of 15 pmol injected (or an incubation 4NC concentration of 0.25 microM), is accurate, reproducible and straightforward. With a chromatographic time of 12 min, 40-50 samples may be analyzed per day. Rates of 4NC formation were linear with time and protein concentration to 50 min and 0.5 mg/ml, respectively. Preliminary studies of 4NP hydroxylation showed that this reaction followed single enzyme Michaelis-Menten kinetics in human liver microsomes. PMID:8376495

  11. Accessing topological order in fractionalized liquids with gapped edges

    NASA Astrophysics Data System (ADS)

    Iadecola, Thomas; Neupert, Titus; Chamon, Claudio; Mudry, Christopher

    2014-11-01

    We consider manifestations of topological order in time-reversal-symmetric fractional topological liquids (TRS-FTLs), defined on planar surfaces with holes. We derive a formula for the topological ground-state degeneracy of such a TRS-FTL, which applies to cases where the edge modes on each boundary are fully gapped by appropriate backscattering terms. The degeneracy is exact in the limit of infinite system size, and is given by qNh, where Nh is the number of holes and q is an integer that is determined by the topological field theory. When the degeneracy is lifted by finite-size effects, the holes realize a system of Nh coupled spinlike q -state degrees of freedom. In particular, we provide examples where Zq quantum clock models are realized on the low-energy manifold of states. We also investigate the possibility of measuring the topological ground-state degeneracy with calorimetry, and briefly revisit the notion of topological order in s -wave BCS superconductors.

  12. High-performance liquid chromatographic analysis of the unusual pathway of oxidation of L-arginine to citrulline and nitric oxide in mammalian cells.

    PubMed

    Chenais, B; Yapo, A; Lepoivre, M; Tenu, J P

    1991-02-22

    A very unusual pathway of the oxidation of L-arginine to citrulline and nitric oxide has been discovered recently in cytotoxic macrophages. In an attempt to detect molecules generated through this metabolic pathway, a fast radio high-performance liquid chromatographic method was developed to analyse the whole set of radiolabelled L-arginine-derived metabolites produced by mammalian cells after appropriate induction. A new intermediate which might be NG-hydroxy-L-arginine was found. PMID:2045453

  13. Chromatographic behaviour of ionic liquid cations in view of quantitative structure-retention relationship.

    PubMed

    Molíková, M; Markuszewski, M J; Kaliszan, R; Jandera, P

    2010-02-19

    The availability of ionic liquids (ILs) in wide areas of application often results in the requirement on their determination. The attention is also often focused on the knowledge of hydrophobicity as it plays a key role in the biological effects, in the assessment of environmental risk and in the prediction of the fate of chemicals in the environment and of its influence on retention in RP HPLC. One can get information regarding hydrophobicity and retention mechanism if quantitative structure-retention relationships (QSRRs) are identified. The QSRRs were derived for logarithms of retention factors extrapolated to a pure water (or aqueous buffer) eluent, log k(w), determined for the pyridinium and imidazolium ionic liquid (IL) cations on two C8 (Supelcosil LC-8-DB, Symmetry C8) and two C18 (ACE 5 C18, Symmetry C18) stationary phases with isocratic elution by a mobile phase consisting of acetonitrile/40 mM phosphate buffer. The analyses of ILs were performed at a flow rate of 1 mL min(-1) with UV detection at 218 nm. The QSRRs were derived based on the retention parameters determined experimentally and the structural descriptors of test analytes from molecular modeling. Separations of ILs were obtained with aqueous acetonitrile buffered at pH 3.55 mobile phases. The statistically most significant two-parameter QSRR regression equations related log k(w) to the solvent accessible surface (SAS) of the analytes and the differences in the energies of the highest occupied and the lowest unoccupied molecular orbitals (diffHL). These equations were especially good in case of columns with the highest carbon loads and larger specific surface areas, i.e. Symmetry C18 and Symmetry C8. On the other hand, the column ACE 5 C18 appeared to produce the best quality separations of the ILs studied. The QSRRs derived in the research shed light on the molecular mechanism of HPLC separation of ILs and helped to predict their relative separations. PMID:20060528

  14. Ionic liquids as mobile phase additives for the high-performance liquid chromatographic analysis of fluoroquinolone antibiotics in water samples.

    PubMed

    Herrera-Herrera, Antonio V; Hernández-Borges, Javier; Rodríguez-Delgado, Miguel Angel

    2008-12-01

    In this work, four ionic liquids differing in the length of the alkyl chain on the imidazolium cation and one ionic liquid containing tetraethylammonium, all with the same counterion, (i.e. 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIm-BF(4)), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIm-BF(4)), 1-hexyl-3-methylimidazolium tetrafluoroborate (HMIm-BF(4)), 1-methyl-3-octylimidazolium tetrafluoroborate (MOIm-BF(4)), and tetraethylammonium tetrafluroborate (Et(4)N-BF(4))) were tested as mobile phase additives for HPLC separation of a group of seven basic fluoroquinolone (FQ) antibiotics for human and veterinary use (i.e. fleroxacin, ciprofloxacin, lomefloxacin, danofloxacin, enrofloxacin, sarafloxacin, and difloxacin) using a conventional reversed-phase Nova-Pak C(18) column. Fluorescence detection was used. Among the ionic liquids selected, use of BMIm-BF(4) enabled effective separation of these compounds with relatively low analysis time (14 min). The best separation was achieved by isocratic elution at 1 mL min(-1) with 5 mmol L(-1) BMIm-BF(4) and 10 mmol L(-1) ammonium acetate at pH 3.0 with 13% (v/v) acetonitrile. Limits of detection (LODs) for fluorescence detection were in the range 0.5-11 microg L(-1). The method was tested by analyzing several water samples after the optimization of a suitable solid-phase extraction (SPE) procedure using Oasis HLB cartridges. Mean recovery values were above 84% for all analytes with LODs in the range 1-29 ng L(-1). PMID:18854988

  15. High-performance liquid chromatographic procedure for routine residue monitoring of seven sulfonamides in milk.

    PubMed

    Furusawa, N; Kishida, K

    2001-12-01

    A simplified method for routine monitoring of 7 residual sulfonamides (SAs) (sulfadiazine (SDZ), sulfamerazine (SMR), sulfadimidine (SDD), sulfamonomethoxine (SMM), sulfamethoxazole (SMX), sulfadimethoxine (SDM), and sulfaquinoxaline (SQ)) in milk using high-performance liquid chromatography (HPLC) with a photodiode array detector is described. The spiked and blank samples were cleaned up by using an Ultrafree-MC/PL centrifugal ultrafiltration unit. For determination/identification, a Mightysil RP-4 GP column and a mobile phase of 25% (v/v) ethanol in water with a photodiode array detector were used. Average recoveries from milk samples spiked with 0.05, 0.1, 0.2, and 0.5 microg mL(-1) of each drug were >82%. The inter- and intra-assay variabilities were 2.0-3.1%. The practical detection limits for 7 SAs were 0.005-0.02 microg mL(-1). The total time and amount of solvent required for the analysis of one sample were <40 min and <6 mL of ethanol, respectively. No toxic solvents were used. PMID:11769794

  16. Spectrophotometric and high performance liquid chromatographic methods for sensitive determination of bisphenol A

    NASA Astrophysics Data System (ADS)

    Zhuang, Yafeng; Zhou, Meng; Gu, Jia; Li, Xiangmei

    2014-03-01

    A new spectrophotometric method for the determination of trace amounts of bisphenol A based on a diazotization-coupling reaction was developed. In acidic solution, clenbuterol was first diazotized with sodium nitrite, then coupled with bisphenol A to from an azo-compound [I] in NH3-NH4Cl buffer, which shows a maximum absorption at 410 nm. The effects of the amount of sodium nitrite, diazo reaction time, the amount of clenbuterol, coupling reaction time and coupling reaction temperature have been examined. Under the optional conditions, the determination of the linear range of bisphenol A is 0.24-8.4 μg/mL, correlation coefficient is 0.9905 and detection limit of this method is 0.15 μg/mL. The spectrophotometric method is simple, rapid, high sensitivity with better accuracy. High performance liquid chromatography (HPLC) technique combined with this new spectrophotometric method has been also developed for the measurement of bisphenol A. The analysis was achieved on a C18 column using water and methanol as a mobile phase and the detection was done spectrophotometrically at 410 nm. These reported methods were applied to the determination of bisphenol A in hot water in contact with commercially available table-water bottle samples.

  17. Gas-liquid chromatographic determination of nifursol in frozen turkey tissues to ten parts per billion.

    PubMed

    Frahm, L J; George, G M; McDonnell, J P

    1975-07-01

    Nifursol (3,5-dinitrosalicylic acid (5-nitrofurfurylidene) hydrazide) is extracted into ethyl acetate from 10 g tissue in the presence of sodium sulfate. Tissue interferences are removed from the tissue extract by washing with petroleum ether after the extract has been transferred into an aqueous solution by evaporation of ethyl acetate. The drug is hydrolyzed under acid conditions to form 5-nitro-2-furaldehyde (5NF). After partition of 5NF from the aqueous phase into benzene the extract is further cleaned up on a Florisil column. The 5NF is eluted from the Florisil column with benzeneethyl acetate. Electron capture gas-liquid chromatography of a 10 mul injection of the concentrated column eluate is the determinative step. Quantitation is accomplished by comparison of the peak height of the sample to the peak height of the standard which is carried through the method simultaneously. Studies of method performance on turkey muscle, liver, kidney, and skin tissues fortified to contain 10 ppb nifursol show a recovery range of 87.4-95.0% and a coefficent of variation range of 5.7-11.2%. PMID:1150608

  18. A sensitive high performance liquid chromatographic method for determining small amounts of glycosylproteins.

    PubMed

    Sampietro, T; Lenzi, S; Giampietro, O; Cecchetti, P; Masoni, A; Navalesi, R

    1987-01-01

    We developed a simple isocratic high performance liquid chromatography (HPLC) method for the quantitative determination of 5-hydroxymethyl-2-furfuraldehyde (5-HMF) liberated by mild hydrolysis of small amounts of glycosyl proteins. The absorbance of hydrolysate components after HPLC separation was recorded at 280 nm. To detect substances possibly interfering with the 5-HMF peak we always recorded the ratio of the peak heights A280 nm/A254 nm which was a constant value of 4.4. For each sample the blank was obtained by reduction with NaBH4 before hydrolysis with oxalic acid 1 mol/l. The best NaBH4/protein ratio was found to be 4 mg/mg. With this method we measured the nonenzymatic glycosylation (glycation) as 5-HMF in samples with a protein concentration as low as 0.8 mg/ml. 5-HMF produced per milligram of protein was independent from protein concentration for a wide range (0.8-10 mg/ml). The mean coefficient of variation for within assay and between precision was 6.8 and 11.6%, respectively. The 5-HMF measured on plasma proteins from normal subjects (n = 7) was 0.16 +/- 0.04 nmol/mg. Protein from insulin-dependent diabetic patients was 0.31 +/- 0.07 nmol/mg. With this method we succeeded in detecting an excessive glycation of platelet membrane proteins in 13 type-I diabetic patients. PMID:3581652

  19. Liquid chromatographic assay for metronidazole and tinidazole: pharmacokinetic and metabolic studies in human subjects.

    PubMed Central

    Nilsson-Ehle, I; Ursing, B; Nilsson-Ehle, P

    1981-01-01

    We developed methods for measuring metronidazole, its two major metabolites, and tinidazole in serum and urine. After treatment of each sample with an equal volume of 5% perchloric acid, the drugs were separated by reverse-phase high-pressure liquid chromatography (retention times, 6 to 18 min). Quantitation was based on spectrometry at 320 nm. These assays were sensitive, rapid, and specific, and recoveries from biological samples were quantitative. Metronidazole and tinidazole were given as rapid intravenous infusions to four healthy human volunteers. The biological half-lives of these two compounds were 5.4 and 11.1 h, respectively. The hydroxy metabolite of metronidazole appeared quickly in serum and was eliminated at a slow rate. The acetic acid metabolite of metronidazole was detected in serum at very low levels and only for a limited time. No metabolic products of tinidazole were found in serum samples. In urine, 43.7% of the administered dose of metronidazole was recovered over a period of 24 h (24.1% of the dose as the hydroxy metabolite, 12.0% as the acetic acid metabolite, and 7.6% as unchanged drug). Only 18.4% of the infused dose of tinidazole was eliminated in urine over a period of 72 h, and no metabolic products were detected. PMID:7294765

  20. Capillary zone electrophoresis and packed capillary column liquid chromatographic analysis of recombinant human interleukin-4.

    PubMed

    Bullock, J

    1993-02-24

    Capillary zone electrophoresis (CZE) and packed capillary column liquid chromatography (micro-LC) have been applied to the analysis of the recombinant human protein interleukin-4 (rhIL-4). Separations for both the parent protein and its enzymatic digest were developed for the purpose of characterizing protein purity and identity. CZE separations of the intact protein were investigated over the pH range of 4.5 to 8.0 using uncoated fused silica capillaries. Gradient reversed-phase micro-LC was performed using 0.32 mm packed capillary columns at flow-rates of 5-6 microliters/min. Emphasis was placed on the ability of these methods to separate close structural variants and degradation products of the protein. Peptide mapping of the tryptic digest of rhIL-4 using a combination of CZE and micro-LC provided complimentary high resolution methods for establishing protein identity. Reproducible separations were achieved using sub-picomol amounts of sample. The advantages and problems encountered with these two techniques for characterizing rhIL-4 were assessed. PMID:8450025

  1. Chromatographic analysis of Polygalae Radix by online hyphenating pressurized liquid extraction

    NASA Astrophysics Data System (ADS)

    Song, Yuelin; Song, Qingqing; Li, Jun; Shi, Shepo; Guo, Liping; Zhao, Yunfang; Jiang, Yong; Tu, Pengfei

    2016-06-01

    Practicing “green analytical chemistry” is of great importance when profiling the chemical composition of complex matrices. Herein, a novel hybrid analytical platform was developed for direct chemical analysis of complex matrices by online hyphenating pressurized warm water extraction followed by turbulent flow chromatography coupled with high performance liquid chromatography-tandem mass spectrometry (PWWE-TFC-LC-MS/MS). Two parallel hollow guard columns acted as extraction vessels connected to a long narrow polyether ether ketone tube, while warm water served as extraction solvent and was delivered at a flow rate of 2.5 mL/min to generate considerable back pressure at either vessel. A column oven heated both the solvent and crude materials. A TFC column, which is advantageous for the comprehensive trapping of small molecular substances from fluids under turbulent flow conditions, was employed to transfer analytes from the PWWE module to LC-MS/MS. Two electronic valves alternated each vessel between extraction and elution phases. As a proof-of-concept, a famous herbal medicine for the treatment of neurodegenerative disorders, namely Polygalae Radix, was selected for the qualitative and quantitative analyses. The results suggest that the hybrid platform is advantageous in terms of decreasing time, material, and solvent consumption and in its automation, versatility, and environmental friendliness.

  2. High-Performance Liquid Chromatographic Resolution of Neutral and Cationic Hetero[6]Helicenes.

    PubMed

    Labrador, Geraldine M; Bosson, Johann; Breitbach, Zachary S; Lim, Yeeun; Francotte, Eric R; Sabia, Rocchina; Villani, Claudio; Armstrong, Daniel W; Lacour, Jérôme

    2016-04-01

    Cationic hetero[6]helicenes , and have been recently disclosed. Herein we report on their enantiomeric separation using high-performance liquid chromatography. Separation of the antipodes can be achieved in preparative scale on neutral adducts with Chiralcel OD-I or Chiralpak ID CSP. Selectivity factors of 1.90, 1.67, and 1.96 were obtained for , , and , respectively. Separation can also be performed on the carbenium ions on regular Chiralpak IA CSP using water-containing eluents, thus allowing for enantiomeric purity determinations in aqueous environments. Resolution of neutral and cationic helicenes is also achieved on more recently developed LARIHC columns. The versatility of the cyclofructan phases allows for baseline separations for both cases and their loading capabilities are demonstrated. Finally, the configurational stability of , , and was measured. For each replacement of an oxygen atom by an amino group, the racemization barrier increases significantly (ΔG(‡)  = 29.8, 36.3 and >37 kcal mol(-1) for , , and respectively). Chirality 28:282-289, 2016. © 2016 Wiley Periodicals, Inc. PMID:26901116

  3. Liquid chromatographic method for toxic biogenic amines in foods using a chaotropic salt.

    PubMed

    Zhong, Jian-Jun; Liao, Ningbo; Ding, Tian; Ye, Xingqian; Liu, Dong-Hong

    2015-08-01

    Direct separation of biogenic amines by reversed-phase liquid chromatography (RPLC) is not an easy task because their basic and hydrophilic characteristics can lead to poor retention, column overloading, peak tailing, and hence low efficiency. Rather than routinely resorting to derivatization or using classical hydrophobic ion-pair reagents (IPR), this work proposes a new RPLC method making use of the chaotropic salt KPF6 as inorganic additive to an acidic acetonitrilic eluent to remedy the difficulties. Amine retention, overload behavior, peak shape, and column efficiency were significantly improved. The use of excess KPF6 led to a very slight decrease of amine retention. Depending on amine, the dependence of the logarithmic retention factor on the volume percent of acetonitrile could be reasonably linear or quite convex. Coupled with UV detection, the method was applied to trace analysis for six biogenic, aromatic or heterocyclic amines in three types of food after a sample cleanup, as necessary, by ion-pair extraction. The reliability of the whole analysis was demonstrated to be satisfactory. The proposed method outperforms existing methods in that it eliminates the need for long and cumbersome derivatization procedures without losing sensitivity; it also represents a good surrogate for classical ion-pair chromatography (IPC) because of the desirable hydrophilicity of chaotropic salts. PMID:26141272

  4. Chromatographic analysis of Polygalae Radix by online hyphenating pressurized liquid extraction

    PubMed Central

    Song, Yuelin; Song, Qingqing; Li, Jun; Shi, Shepo; Guo, Liping; Zhao, Yunfang; Jiang, Yong; Tu, Pengfei

    2016-01-01

    Practicing “green analytical chemistry” is of great importance when profiling the chemical composition of complex matrices. Herein, a novel hybrid analytical platform was developed for direct chemical analysis of complex matrices by online hyphenating pressurized warm water extraction followed by turbulent flow chromatography coupled with high performance liquid chromatography-tandem mass spectrometry (PWWE-TFC-LC-MS/MS). Two parallel hollow guard columns acted as extraction vessels connected to a long narrow polyether ether ketone tube, while warm water served as extraction solvent and was delivered at a flow rate of 2.5 mL/min to generate considerable back pressure at either vessel. A column oven heated both the solvent and crude materials. A TFC column, which is advantageous for the comprehensive trapping of small molecular substances from fluids under turbulent flow conditions, was employed to transfer analytes from the PWWE module to LC-MS/MS. Two electronic valves alternated each vessel between extraction and elution phases. As a proof-of-concept, a famous herbal medicine for the treatment of neurodegenerative disorders, namely Polygalae Radix, was selected for the qualitative and quantitative analyses. The results suggest that the hybrid platform is advantageous in terms of decreasing time, material, and solvent consumption and in its automation, versatility, and environmental friendliness. PMID:27272557

  5. Chromatographic analysis of Polygalae Radix by online hyphenating pressurized liquid extraction.

    PubMed

    Song, Yuelin; Song, Qingqing; Li, Jun; Shi, Shepo; Guo, Liping; Zhao, Yunfang; Jiang, Yong; Tu, Pengfei

    2016-01-01

    Practicing "green analytical chemistry" is of great importance when profiling the chemical composition of complex matrices. Herein, a novel hybrid analytical platform was developed for direct chemical analysis of complex matrices by online hyphenating pressurized warm water extraction followed by turbulent flow chromatography coupled with high performance liquid chromatography-tandem mass spectrometry (PWWE-TFC-LC-MS/MS). Two parallel hollow guard columns acted as extraction vessels connected to a long narrow polyether ether ketone tube, while warm water served as extraction solvent and was delivered at a flow rate of 2.5 mL/min to generate considerable back pressure at either vessel. A column oven heated both the solvent and crude materials. A TFC column, which is advantageous for the comprehensive trapping of small molecular substances from fluids under turbulent flow conditions, was employed to transfer analytes from the PWWE module to LC-MS/MS. Two electronic valves alternated each vessel between extraction and elution phases. As a proof-of-concept, a famous herbal medicine for the treatment of neurodegenerative disorders, namely Polygalae Radix, was selected for the qualitative and quantitative analyses. The results suggest that the hybrid platform is advantageous in terms of decreasing time, material, and solvent consumption and in its automation, versatility, and environmental friendliness. PMID:27272557

  6. A simple high-performance liquid chromatographic practical approach for determination of flurbiprofen

    PubMed Central

    Akhlaq, Muhammad; Khan, Gul Majid; Wahab, Abdul; Khan, Arshad; Hussain, Abid; Nawaz, Asif; Abdelkader, Hamdy

    2011-01-01

    A simple, rapid, sensitive, and specific high-performance liquid chromatography (HPLC) assay for flurbiprofen has been developed and validated practically. The chromatography was conducted using Gemini C18 column (5 μm; 4.6 mm × 250 mm, Phenomenex, California, USA). The mobile phase containing disodium hydrogen phosphate solution (30 mM) pH 7.0 and acetonitrile (50:50); and the isocratic flow rate of 1.0 ml/min were used in the current study. Detection was made at 247 nm. The calibration curve was linear (r ≥ 0.9996) over the concentration range of 5-50 μm/ml. Mean percentage (%) recovery ± % relative standard deviation (RSD) ranged from 97.07 ± 0.008 to 103.66 ± 0.013. Within-day and between-day precision were also in acceptable range of 98.83 ± 0.004 to 104.56 ± 0.009. In order to confirm the practical applicability of the method developed, flurbiprofen controlled release matrix tablets were subjected to the dissolution studies and the release rate was analyzed. The reported HPLC for flurbiprofen provides several advantages of simplicity, high specificity, accuracy, and very short run-cycle time. It is suggested that the method should be used for the routine quality control analysis of flurbiprofen pure drug and its dosage forms. PMID:22171311

  7. Liquid chromatographic method for nicarbazin in broiler feeds and premixtures: development, validation, and interlaboratory study.

    PubMed

    de Jong, Jacob; Tomassen, Marinka; Driessen, Jaap; Keukens, Henk; Hans-Artur, Putzka; Brambilla, Glanfranco

    2004-01-01

    A reversed-phase liquid chromatography method for nicarbazin in broiler feeds and premixtures was developed, validated, and interlaboratory studied. The extraction solvent was an acetonitrile-methanol (1 + 1) mixture. For feedingstuffs, water was also added. The 4,4'-dinitrocarbanilide moiety of nicarbazin was detected at a wavelength of 350 nm. Recovery was > or =87%. At 20 mg/kg, the repeatability was 0.7% and the within-laboratory reproducibility was 2.7%. The limit of determination was <20 mg/kg. Other feed additives did not interfere in the assay that proved to be applicable to broiler feeds from different European Union countries. In an interlaboratory study, 4 positive broiler feeds, 1 blank pig feed, and 1 broiler premixture were analyzed by 19 laboratories using the method developed in this study. The relative standard deviation for repeatability (RSDr) of the feedingstuffs (20-240 mg/kg) varied between 2.6 and 10.2%. The HORRAT ranged between 0.70 and 1.22. Recoveries were 91-108%. Three laboratories detected small signals in the blind blank samples, ranging from 0.4 to 2 mg/kg. For the premixture, acceptable results for reproducibility could only be obtained after the sample weight and volume of extraction had been doubled. To avoid excessive dilution of the extracts, the range of the calibration curve had also been doubled. With this modified method, the RSDr was 5.7% and the HORRAT was 1.95 (10 laboratories). PMID:15675436

  8. Liquid chromatographic analysis of coal surface properties. Final report, September 1991--February 1995

    SciTech Connect

    Kwon, K.C.

    1996-03-01

    Experiments on equilibrium adsorption loadings of various probe compounds on 60-200 mesh Illinois {number_sign}6 coal (PSOC-1539), Adaville {number_sign}1 coal (PSOC-1544), Wyodak coal (PSOC-1545) and Pittsburgh {number_sign}8 coal (PSOC-1549) were performed. the probe compounds include m-cresol, p-cresol, o-cresol, phenol, n-octanol, n-heptanol, n-propanol, isopropanol n-butanol, s-butanol, 2-butanol, t-butanol, 2-naphthol, cyclohexanol, 2-methyl-1-pentanol (2M1P), 4-methyl-2-pentanol (4M2P), benzene and toluene. Equilibrium adsorption of various probe compounds on the coals were measured with the inverse liquid chromatography method. Experiments on flotation of various 60-200 mesh treated coals such as Illinois {number_sign}6 coal (PSOC-1539), Adaville {number_sign}1 coal (PSOC-1544), Wyodak coal (PSOC-1545) and Pittsburgh {number_sign}8 coal (PSOC-1549) were performed. The chosen coals were treated with steam, nitrogen and air at 1 atm and 125-225{degrees}C for 24 hours. The coals were treated with water as well as 20-1000 ppm aqueous alcohol solutions for 3-24 hours at 150-225{degrees}C. The coals also were treated with 20-ppm alcohol aqueous solutions for 1-24 hours at the 0.002-g/min mass flow rate of alcohol aqueous solutions and at 225{degrees}C. Flotation experiments were conducted with a 500-cm{sup 3} batch-type micro flotation apparatus, introducing nitrogen at the bottom of the apparatus. This final report was prepared with the experimental data obtained during the period of September 1991-March 1994.

  9. Simultaneous determination of piracetam and vincamine by spectrophotometric and high-performance liquid chromatographic methods.

    PubMed

    El-Saharty, Yasser Shaker Ibrahim

    2008-01-01

    A mixture of piracetam and vincamine was determined by 3 different methods. The first was the determination of piracetam and vincamine using the ratio-spectra first-derivative (DD1) spectrophotometric technique at 209 and 293 nm in concentration ranges of 10-45 and 2-14 microg/mL with mean recoveries of 99.22 +/- 0.72 and 99.67 +/- 0.79%, respectively. The second method was based on the resolution of the 2 components by bivariate calibration depending on a mathematic algorithm that provides simplicity and rapidity. The method depended on quantitative evaluation of the absorbencies at 210 and 225 nm in concentration ranges of 5-45 and 2-14 microg/mL, with mean recoveries of 100.33 +/- 0.54 and 100.44 +/- 0.98% for piracetam and vincamine, respectively. The third method was reversed-phase liquid chromatography using 0.05 M potassium dihydrogen phosphate-methanol (50 + 50, v/v) as the mobile phase, with the pH adjusted to 3.5 with phosphoric acid. The eluent was monitored at 215 nm in concentration ranges of 5-100 and 2-200 microg/mL, with mean recoveries of 99.62 +/- 0.67 and 99.32 +/- 0.85% for piracetam and vincamine, respectively. The suggested procedures were checked using laboratory-prepared mixtures and were successfully applied for the analysis of their pharmaceutical preparation. The methods retained their accuracy and precision when applying the standard addition technique. The results obtained by applying the proposed methods were statistically analyzed and compared with those obtained by the manufacturer's method. PMID:18476342

  10. A high-performance liquid chromatographic method for the determination of hypoxanthine, xanthine, uric acid and allantoin in serum.

    PubMed

    Kock, R; Delvoux, B; Greiling, H

    1993-05-01

    A method was developed for the simultaneous determination of hypoxanthine, xanthine, uric acid and allantoin based on isocratic reversed-phase chromatography. This HPLC-method additionally allows the direct determination with UV-detection of inosine-5'-phosphate, uridine, thymine, orotic acid, allopurinol and oxipurinol, besides hypoxanthine, xanthine and uric acid in the same chromatographic run. Allantoin elutes in this system near the void volume and a fraction is collected covering the retention time range for this substance. After hydrolysis allantoin is converted to glyoxylate-2,4-dinitrophenylhydrazone, rechromatographed and detected at 360 nm. The coefficient of variation for this method does not exceed 5.0% for a serum concentration of 0.3 mumol/l hypoxanthine and is not greater than 5.3% for a xanthine concentration of 0.3 mumol/l serum. Recoveries were 90-110% for both hypoxanthine and xanthine. The determination of uric acid had an imprecision and inaccuracy not exceeding 1.45% in the concentration range of 103-568 mumol/l. Due to the more complex procedure required for the determination of allantoin, the coefficient of variation between days was 13.6% for a sample containing 0.8 mumol/l allantoin and the recoveries for this analyte were in the range of 86-93%. Reference ranges (mean +/- SD) determined on 171 serum samples from healthy adults were 12.7 +/- 6.6 mumol/l for hypoxanthine, 3.3 +/- 1.4 mumol/l for xanthine, and 15.7 +/- 7.9 mumol/l for allantoin. No significant age or sex dependence was observed. Uric acid concentrations were 320 +/- 55 mumol/l serum for men and 206 +/- 55 mumol/l for women. PMID:8357939

  11. High-performance liquid chromatographic determination of arbutin in skin-whitening creams and medicinal plant extracts.

    PubMed

    Thongchai, Wisanu; Liawruangrath, Boonsom; Liawruangrath, Saisunee

    2007-01-01

    A high-performance liquid chromatographic method was developed for quantitative analysis of arbutin. The arbutin was separated on an ODS Hypersil C(18) column with a mobile phase of water:methanol:0.1 M hydrochloric acid (89:10:1, v/v/v). The level of arbutin was measured by means of UV detection at 222 nm. The optimum conditions for arbutin quantitative analysis were investigated. The calibration curve was found to be linear up to 1,000 microg/ml(-1) of arbutin concentration, and the working calibration curve for arbutin determination over the range 0.5-30.0 microg/ml(-1) of arbutin (r(2)=0.9999) was established. The relative standard deviations for intraday and interday were found to be 0.98% and 1.15%, respectively. A detection limit (3sigma) and quantitation limit (10sigma) of 0.02 microg/ml(-1) and 0.2 microg/ml(-1), respectively, and a mean percentage recovery of the spiked arbutin of 99.88 +/- 1.12% were obtained. The proposed method has been applied to the determination of arbutin in commercial skin-whitening creams (Arbuwhite cream, Super Whitening cream, and Shiseido cream) with average contents of 7.60, 5.30, and 57.90 mg/g(-1), respectively. It was also applied to the determination of arbutin in medicinal plant extracts from Betula alnoides Buch. Ham., Clerodendrum petasites S. Moore, Curculigo latifolia Dryand. Var. latifolia, and Hesperethusa crenulata (Roxb.) Roem, levels of which were found to be 3.50, 1.50, 1.10, and 0.12 microg/g(-1), respectively (no article reported in the literature about arbutin analysis). The proposed HPLC method is rapid, simple, and selective for routine analysis. PMID:17342266

  12. Determination of diphenamide, napropamide and metolachlor in tobacco by gel permeation chromatographic clean-up and high performance liquid chromatography.

    PubMed

    Liu, Hongxia; Dang, Yuanlin; Zhang, Shusheng; Liu, Huimin; Qu, Lingbo; Liao, Xincheng; Zhao, Yufen; Wu, Yangjie

    2005-05-01

    Diphenamide, napropamide and metolachlor (FIG. 1) are selective, pre-emergence arylamide herbicides used to control the growth of annual grasses and broadleaf weeds in a variety of fields, e.g. fruit trees, nuts, corns, green crops, etc. They possess high activity and moderate toxicity. For food and environment safety, the detailed investigations on their residues and metabolism are very important. Diphenamide, napropamide and metolachlor in the pesticide products, serum, urine, soil, environmental water, fruits and wine have been widely analyzed by ELISA, fluorescence, phosphorescence, capillary electrophoresis, high performance liquid chromatography (HPLC), gas chromatography(GC) and GC mass spectrometry (GC-MS). However, to our knowledge, simultaneous residue analysis of diphenamide, napropamide and metolachlor in tobacco samples has not been extensively documented. Tobacco is greatly consumed by smokers throughout the world. The pesticide residue in tobaccos might be potentially harmful to smokers' health. With this in mind the residue determination and control of diphenamide, napropamide and metolachlor in the tobacco leaves are very important for tobacco products and consumers. For these three herbicides, the tolerable maximum residue limits (MRLs) have been limited ranging from 0.05 (for tobacco products) to 5 mg/kg (for tobacco leaves) in different European countries. For the complex tobacco samples, the GC and HPLC with UV detection suffer from matrix interference making quantification and identification of these herbicides difficult. In such cases the removal of the matrix effects and identification of the target compounds are of great importance. The present work reports the extraction and clean up procedures, as well as, the chromatographic conditions developed for the simultaneous determination of diphenamide, napropamide and metolachlor residues in the fluecured tobacco leaves, from the different sources using HPLC-UV method. PMID:16477944

  13. Optimization of a liquid chromatographic method for determination of malachite green and its metabolites in fish tissues

    USGS Publications Warehouse

    Plakas, S.M.; ELSaid, K.R.; Stehly, G.R.; Roybal, J.E.

    1995-01-01

    A liquid chromatographic (LC) method was adapted and optimized for the determination of malachite green and its metabolites in fish plasma and muscle, Residues in plasma were extracted with acetonitrile, the extract was evaporated to dryness, and residues were resolubilized for LC analysis, Residues in muscle were extracted with an acetonitrile-acetate buffer mixture, reextracted with acetonitrile, and partitioned into methylene chloride with final cleanup on alumina and propylsulfonic acid solid-phase extraction columns, Residue levels were determined by using an LC cyano column with a PbO2 postcolumn and visible detection (618 nm). Overall mean recoveries of parent malachite green (MG-C) and its major metabolite, leucomalachite green (MG-L), from plasma were 93 and 87%, respectively, at fortification levels ranging from 25 to 250 ppb, Overall mean recoveries of MG-C and MG-L from muscle were 85 and 95%, respectively, at fortification levels ranging from 5 to 100 ppb, Relative standard deviations (RSDs) of recoveries at all fortification levels ranged from 3.9 to 7.0% for plasma and from 2.1 to 5.2% for muscle, The method was applied to incurred residues in tissues sampled from catfish after waterborne exposure to [C-14]MG-C. Mean recoveries of total radioactive residues in plasma and muscle throughout the extraction and cleanup process were 88 and 87%, respectively, and corresponding RSDs for MG-C and MG-L were in the same range as those for fortified tissues, MG-L, was confirmed as the major metabolite of MG-C in catfish.

  14. Spectrophotometric, difference spectroscopic, and high-performance liquid chromatographic methods for the determination of cefixime in pharmaceutical formulations.

    PubMed

    Shah, Paresh B; Pundarikakshudu, Kilambi

    2006-01-01

    Three simple and sensitive spectrophotometric, difference spectroscopic, and liquid chromatographic (LC) methods are described for the determination of cefixime. The first method is based on the oxidative coupling reaction of cefixime with 3-methyl-2-benzothiazolinon hydrazone HCI in presence of ferric chloride. The absorbance of reaction product was measured at the maximum absorbance wavelength (wavelength(max)), 630 nm. The difference spectroscopic method is based on the measurement of absorbance of cefixime at the absorbance maximum, 268 nm, and minimum, 237 nm. The measured value was the amplitude of maxima and minima between 2 equimolar solutions of the analyte in different chemical forms, which exhibited different spectral characteristics. The conditions were optimized, and Beer's law was obeyed for cefixime at 1 to 16 microg/mL and 10 to 50 microg/mL, respectively. The third method, high-performance LC, was developed for the determination of cefixime using 50 mM potassium dihydrogen phosphate (pH 3.0)-methanol (78 + 22, v/v) as the mobile phase and measuring the response at wavelength(max) 286 nm. The analysis was performed on a Lichrospher RPC18 column. The calibration curve was obtained for cefixime at 5 to 250 microg/mL, and the mean recovery was 99.71 +/- 0.01%. The methods were validated according to the guidelines of the U.S. Pharmacopoeia and also assessed by applying the standard addition technique. The results obtained in the analysis of dosage forms agreed well with the contents stated on the labels. PMID:16915834

  15. Quantification of bovine casein fractions by direct chromatographic analysis of milk. Approaching the application to a real production context.

    PubMed

    Bonizzi, Ivan; Buffoni, Joanna Natalia; Feligini, Maria

    2009-01-01

    The ability to quantify the casein content by an exact and cost-effective approach represents an issue of crucial importance in the dairy industry as the natural variations in milk protein concentration can markedly affect the yield of the cheesemaking processes, thus causing a direct and significant economic impact on the producers. In this work, the separation and quantification of alpha(s1)-, alpha(s2)-, kappa- and beta-casein was carried out by direct RP-HPLC analysis of milk. The identification of each casein was established by electrospray ionization mass spectrometry. The data show that this method is able to effectively separate the bovine casein fractions, it provides simplified analytical conditions (with special regard to mobile phase composition and gradient profile) and faster separation while ensuring adequate precision to achieve reliable quantifications in milk samples from dairy production. PMID:19062022

  16. Capillary liquid chromatography fraction collection and postcolumn reaction using segmented flow microfluidics.

    PubMed

    Nie, Jing; Kennedy, Robert T

    2013-11-01

    A challenge for capillary LC (cLC) is fraction collection and the manipulation of fractions from microscale columns. An emerging approach is the use of segmented flow or droplet technology to perform such tasks. In this work, a fraction collection and postcolumn reaction system based on segmented flow was developed for the gradient cLC of proteins. In the system, column effluent and immiscible oil are pumped into separate arms of a tee resulting in regular fractions of effluent segmented by oil. Fractions were generated at 1 Hz corresponding to 5 nL volumes. The fraction collection rate was high enough to generate over 30 fractions per peak and preserve chromatographic resolution achieved for a five-protein test mixture. The resulting fractions could be stored and subsequently derivatized for fluorescence detection by pumping them into a second tee where naphthalene dicarboxyaldehyde, a fluorogenic reagent, was pumped into a second arm and added to each fraction. Proteins were derivatized within the droplets enabling postcolumn fluorescence detection of the proteins. The experiments demonstrate that fraction collection from cLC by segmented flow can be extended to proteins. Further, they illustrate a potential workflow for protein analysis based on postcolumn derivatization for fluorescence detection. PMID:24039151

  17. Development of post-column enzymic reactors with immobilized alcohol oxidase for use in the high-performance liquid chromatographic assay of alcohols with electrochemical detection.

    PubMed

    Tagliaro, F; Schiavon, G; Dorizzi, R; Marigo, M

    1991-01-18

    The development of a very sensitive, direct injection high-performance liquid chromatographic method, using a post-column reactor with immobilized alcohol oxidase, was undertaken with the aim of determining methanol and ethanol levels in microlitre volumes of biological samples. After reversed-phase chromatography to separate methanol and ethanol, the analytes were enzymically converted into the respective aldehydes with formation of stoichiometric amounts of hydrogen peroxide, which could be measured via electrochemical oxidation at a platinum electrode. Some problems were encountered in the development of solid-phase enzymic reactors, using a delicate enzyme, that is prone to lose activity, such as alcohol oxidase. Owing to the slightly alkaline pH required for the optimum activity of alcohol oxidase, polymeric columns seemed to be preferable for the chromatography. HEMA copolymer was chosen as the stationary phase, but the methanol and ethanol peaks eluted close together and posed severe problems of limiting post-column band spreading. Reactors based on coarse supports for enzyme immobilization gave unacceptable band spreading, causing the methanol and ethanol peaks to overlap. On the other hand high-performance liquid chromatographic packings maintained the efficiency of the chromatographic separation, quite independently of the reactor volume. Polymeric supports proved superior to silicas in maintaining the enzyme activity. However, relevant changes in the enzyme substrate specificity were observed after immobilization. PMID:2061376

  18. Development and validation of a reversed-phase liquid chromatographic method for analysis of estradiol valerate and medroxyprogesterone acetate in a tablet formulation.

    PubMed

    Segall, A; Hormaechea, F; Vitale, M; Perez, V; Pizzorno, M T

    1999-04-01

    A simple and accurate liquid chromatographic method was developed for estimation of estradiol valerate and medroxyprogesterone acetate in pharmaceuticals. Drugs were chromatographed on a reverse phase C18 column, using a mixture (30:70) of ammonium nitrate buffer and acetonitrile and eluants monitored at a wavelength of 280 nm. Solution concentrations were measured on a weight basis to avoid the use of an internal standard. The method was statistically validated for its linearity, accuracy, precision and selectivity. Due to its simplicity and accuracy, the authors believe that the method may be used for routine quality control analysis. It does not require any specific sample preparation except the use of a column guard before the analytical column and suitable prefilter attached to the syringe prior to injection. PMID:10698544

  19. Liquid chromatographic determination of aniline in table-top sweeteners based on pre-column derivatization with 1,2-naphthoquinone-4-sulfonate.

    PubMed

    Hernando, D; Saurina, J; Hernández-Cassou, S

    1999-10-29

    A liquid chromatographic method for the determination of aniline in cyclamate sweeteners based on a pre-column derivatization with 1,2-naphthoquinone-4-sulfonate (NQS) is proposed. Aniline traces were extracted from the cyclamate samples using dichloromethane. After solvent evaporation, the dry residue was derivatized with NQS at pH 9.5 and 85 degrees C for 1 min. The aniline derivative, which was extracted from the reacting mixture, was redissolved in the eluent solution and injected into the chromatographic system. The separation of aniline derivative from other amine impurities was carried out in a C18 column using a 2% acetic acid-methanol (40:60, v/v) mobile phase. Results from the analysis of aniline in the sweetener samples with the proposed method were compared with those from the standard method. A good concordance between the two methods was observed. PMID:10574215

  20. Composition and thermal characteristics of Madhuca longifolia seed fat and its solid and liquid fractions.

    PubMed

    Marikkar, J M N; Ghazali, H M; Long, K

    2010-01-01

    This study was to characterize the seed fat from Madhuca longifolia known as Mee fat and its solid and liquid fractions with the objective of distinguishing them. A sample of Mee fat was partitioned into solid and liquid fractions using acetone as the solvent medium. The isolated fractions were compared to the native Mee fat sample with respect to various physico-chemical parameters using standard chemical methods as well as instrumental techniques such as, gas liquid chromatography (GLC), reversed-phase high performance liquid chromatography (RP-HPLC), and differential scanning calorimetry (DSC). Basic analyses indicated that there were wide variations between the native sample and its fractions with respect to iodine value (IV), and slip melting point (SMP). The cloud point (CP) of the liquid fraction was found to be 10.5 degrees C. Fatty acid compositional analyses showed that the proportion of saturated fatty acids (SFA) such as palmitic and stearic went up in the high-melting fraction (HMF) while in low-melting fraction (LMF) the proportion of unsaturated fatty acid (USFA) such as oleic and lenoleic increased. According to the HPLC analyses, Mee fat had a tiacyl glycerol (TAG) sequence similar to that of palm oil. After fractionation, the solid and liquid fractions obtained were found to have TAG profiles very much different from the native sample. Thermal analyses by DSC showed that Mee fat had two-widely separated high and low melting thermal transitions, a feature which was beneficial for the effective separation of solid and liquid fractions. The thermal profiles displayed by the fractions were clearly distinguishable from that of the native sample. PMID:20032594

  1. Indirect reversed-phase high-performance liquid chromatographic and direct thin-layer chromatographic enantioresolution of (R,S)-Cinacalcet.

    PubMed

    Bhushan, Ravi; Dubey, Rituraj

    2011-06-01

    Enantioresolution of the calcimimetic drug (R,S)-Cinacalcet was achieved using both indirect and direct approaches. Six chiral variants of Marfey's reagent having L-Ala-NH(2), L-Phe-NH(2), L-Val-NH(2), L-Leu-NH(2), L-Met-NH(2) and D-Phg-NH(2) as chiral auxiliaries were used as derivatizing reagents under microwave irradiation. Derivatization conditions were optimized. Reversed-phase high-performance liquid chromatography was successful using binary mixtures of aqueous trifluoroacetic acid and acetonitrile for separation of diastereomeric pairs with detection at 340 nm. Thin silica gel layers impregnated with optically pure L-histidine and L-arginine were used for direct resolution of enantiomers. The limit of detection was found to be 60 pmol in HPLC while in TLC it was found to be in the range of 0.26-0.28 µg for each enantiomers. PMID:20737655

  2. Identification of humic-like substances (HULIS) in oxygenated organic aerosols using NMR and AMS factor analyses and liquid chromatographic techniques

    NASA Astrophysics Data System (ADS)

    Paglione, M.; Kiendler-Scharr, A.; Mensah, A. A.; Finessi, E.; Giulianelli, L.; Sandrini, S.; Facchini, M. C.; Fuzzi, S.; Schlag, P.; Piazzalunga, A.; Tagliavini, E.; Henzing, J. S.; Decesari, S.

    2013-06-01

    The atmospheric organic aerosol composition is characterized by a great diversity of functional groups and chemical species challenging simple classification schemes. Traditional off-line chemical methods identified chemical classes based on the retention behavior on chromatographic columns and absorbing beds. Such approach led to the isolation of complex mixtures of compounds such as the humic-like substances (HULIS). More recently, on-line aerosol mass spectrometry (AMS) was employed to identify chemical classes by extracting fragmentation patterns from experimental data series using statistical methods (factor analysis), providing simplified schemes for oxygenated organic aerosols (OOAs) classification on the basis of the distribution of oxygen-containing functionalities. The analysis of numerous AMS datasets suggested the occurrence of very oxidized OOAs which were postulated to correspond to the HULIS. However, only a few efforts were made to test the correspondence of the AMS classes of OOAs with the traditional classification from the off-line methods. In this paper, we consider a case study representative for polluted continental regional background environments. We examine the AMS factors for OOAs identified by positive matrix factorization (PMF) and compare to chemical classes of water-soluble organic carbon (WSOC) analysed off-line on a set of filters collected in parallel. WSOC fractionation was performed by means of factor analysis applied to H-NMR spectroscopic data, and by applying an ion-exchange chromatographic method for direct quantification of HULIS. Results show that the very oxidized low-volatility OOAs from AMS correlate with the NMR factor showing HULIS features and also with true "chromatographic" HULIS. On the other hand, UV/VIS-absorbing polyacids (or HULIS sensu stricto) isolated on ion-exchange beds were only a fraction of the AMS and NMR organic carbon fractions showing functional groups attributable to highly substituted carboxylic

  3. Identification of humic-like substances (HULIS) in oxygenated organic aerosols using NMR and AMS factor analyses and liquid chromatographic techniques

    NASA Astrophysics Data System (ADS)

    Paglione, M.; Kiendler-Scharr, A.; Mensah, A. A.; Finessi, E.; Giulianelli, L.; Sandrini, S.; Facchini, M. C.; Fuzzi, S.; Schlag, P.; Piazzalunga, A.; Tagliavini, E.; Henzing, J. S.; Decesari, S.

    2014-01-01

    The atmospheric organic aerosol composition is characterized by a great diversity of functional groups and chemical species, challenging simple classification schemes. Traditional offline chemical methods identify chemical classes based on the retention behaviour on chromatographic columns and absorbing beds. Such an approach led to the isolation of complex mixtures of compounds such as the humic-like substances (HULIS). More recently, online aerosol mass spectrometry (AMS) was employed to identify chemical classes by extracting fragmentation patterns from experimental data series using statistical methods (factor analysis), providing simplified schemes for the classification of oxygenated organic aerosols (OOAs) on the basis of the distribution of oxygen-containing functionalities. The analysis of numerous AMS data sets suggested the occurrence of very oxidized OOAs which were postulated to correspond to HULIS. However, only a few efforts were made to test the correspondence of the AMS classes of OOAs with the traditional classifications from the offline methods. In this paper, we consider a case study representative of polluted continental regional background environments. We examine the AMS factors for OOAs identified by positive matrix factorization (PMF) and compare them to chemical classes of water-soluble organic carbon (WSOC) analysed offline on a set of filters collected in parallel. WSOC fractionation was performed by means of factor analysis applied to proton nuclear magnetic resonance (NMR) spectroscopic data, and by applying an ion-exchange chromatographic method for direct quantification of HULIS. Results show that the very oxidized low-volatility OOAs from AMS correlate with the NMR factor showing HULIS features and also with true "chromatographic" HULIS. On the other hand, UV/VIS-absorbing polyacids (or HULIS {sensu stricto}) isolated on ion-exchange beds were only a fraction of the AMS and NMR organic carbon fractions showing functional groups

  4. Laser videofluorometer system for real-time characterization of high-performance liquid chromatographic eluate. [3-hydroxy-benzo(a)pyrene

    SciTech Connect

    Skoropinski, D.B.; Callis, J.B.; Danielson, J.D.S.; Christian, G.D.

    1986-11-01

    A second generation videofluorometer has been developed for real-time characterization of high-performance liquid chromatographic eluate. The instrument features a nitrogen-laser-pumped dye laser as excitation source and quarter meter polychromator/microchannel plate-intensified diode array as fluorescence detector. The dye laser cavity is tuned with a moving-iron galvanometer scanner grating drive, permitting the laser output to be changed to any wavelength in its range in less than 40 ms. Thus, the optimum excitation wavelength can be chosen for each chromatographic region. A minimum detection limit of 13 pptr has been obtained for 3-hydroxy-benzo(a)pyrene in a conventional fluorescence cuvette with a 30-s data acquisition. For the same substance eluted chromatographically, a minimum detection limit of 50 pg has been obtained, and a linear dynamic range of greater than 3 orders of magnitude observed. An extract of soil that had been contaminated with polyaromatic hydrocarbons was analyzed as a practical test of the system, permitting the quantitation of three known species, and the identification and quantitation of a previously unknown fourth compound.

  5. Development of Chromatographic Fingerprints of Eurycoma longifolia (Tongkat Ali) Roots Using Online Solid Phase Extraction-Liquid Chromatography (SPE-LC).

    PubMed

    Zaini, Nor Nasriah; Osman, Rozita; Juahir, Hafizan; Saim, Norashikin

    2016-01-01

    E. longifolia is attracting interest due to its pharmacological properties and pro-vitality effects. In this study, an online SPE-LC approach using polystyrene divinyl benzene (PSDVB) and C18 columns was developed in obtaining chromatographic fingerprints of E. longifolia. E. longifolia root samples were extracted using pressurized liquid extraction (PLE) technique prior to online SPE-LC. The effects of mobile phase compositions and column switching time on the chromatographic fingerprint were optimized. Validation of the developed method was studied based on eurycomanone. Linearity was in the range of 5 to 50 µg∙mL(-1) (r² = 0.997) with 3.2% relative standard deviation of peak area. The developed method was used to analyze 14 E. longifolia root samples and 10 products (capsules). Selected chemometric techniques: cluster analysis (CA), discriminant analysis (DA), and principal component analysis (PCA) were applied to the fingerprint datasets of 37 selected peaks to evaluate the ability of the chromatographic fingerprint in classifying quality of E. longifolia. Three groups were obtained using CA. DA yielded 100% correlation coefficient with 19 discriminant compounds. Using PCA, E. longifolia root samples were clearly discriminated from the products. This study showed that the developed online SPE-LC method was able to provide comprehensive evaluation of E. longifolia samples for quality control purposes. PMID:27144555

  6. Chemometrics-assisted high performance liquid chromatography-diode array detection strategy to solve varying interfering patterns from different chromatographic columns and sample matrices for beverage analysis.

    PubMed

    Yin, Xiao-Li; Wu, Hai-Long; Gu, Hui-Wen; Hu, Yong; Wang, Li; Xia, Hui; Xiang, Shou-Xia; Yu, Ru-Qin

    2016-02-26

    This work reports a chemometrics-assisted high performance liquid chromatography-diode array detection (HPLC-DAD) strategy to solve varying interfering patterns from different chromatographic columns and sample matrices for the rapid simultaneous determination of six synthetic colorants in five kinds of beverages with little sample pretreatment. The investigation was performed using two types of LC columns under the same elution conditions. Although analytes using different columns have different co-elution patterns that appear more seriously in complex backgrounds, all colorants were properly resolved by alternating trilinear decomposition (ATLD) method and accurate chromatographic elution profiles, spectral profiles as well as relative concentrations were obtained. The results were confirmed by those obtained from traditional HPLC-UV method at a particular wavelength and the results of both methods were consistent with each other. All results demonstrated that the proposed chemometrics-assisted HPLC-DAD method is accurate, economical and universal, and can be promisingly applied to solve varying interfering patterns from different chromatographic columns and sample matrices for the analysis of complex food samples. PMID:26830638

  7. Simultaneous high performance liquid chromatographic determination of vanadium, nickel, iron and copper in crude petroleum oils using bis(acetylpivalylmethane)ethylenediimine as a complexing reagent.

    PubMed

    Khuhawar, M Y; Lanjwani, S N

    1996-05-01

    A method is described for the simultaneous high performance liquid chromatographic (HPLC) determination of copper, iron, nickel and vanadium, based on complexation of analytes by bis(acetylpivalylmethane)ethylenediimine (H(2)APM(2)en) followed by solvent extraction and HPLC separation on a reversed-phase. C-18, 5 microm column with UV detection at 260 nm. The method has been applied to the determination of metals in crude petroleum oils collected from the South Indus Basin oil fields. The results obtained are compared with those obtained by flame atomic absorption spectrometry. PMID:18966546

  8. Fractional shot noise in partially gapped Tomonaga-Luttinger liquids

    NASA Astrophysics Data System (ADS)

    Cornfeld, Eyal; Neder, Izhar; Sela, Eran

    2015-03-01

    We depict a family of one-dimensional systems where one can create and detect fractional charges. These charges are produced via interacting one-dimensional conductors connected to noninteracting leads. At certain electron densities, some distinct modes develop an energy gap due to electron-electron interactions. This gap allows for tunneling events inside the conductor, which generate electric current noise. The resulting fractional noise's Fano factor depends only on the identification of the gapped mode, and is insensitive to additional interactions in the conductor. These effects can be realized in either quantum wires or edges of quantum Hall systems.

  9. Rapid flow fractionation of particles combining liquid and particulate dielectrophoresis

    NASA Technical Reports Server (NTRS)

    King, Michael R. (Inventor); Lomakin, Oleg (Inventor); Jones, Thomas B. (Inventor); Ahmed, Rajib (Inventor)

    2007-01-01

    Rapid, size-based, deposition of particles from liquid suspension is accomplished using a nonuniform electric field created by coplanar microelectrode strips patterned on an insulating substrate. The scheme uses the dielectrophoretic force both to distribute aqueous liquid containing particles and, simultaneously, to separate the particles. Size-based separation is found within nanoliter droplets formed along the structure after voltage removal. Bioparticles or macromolecules of similar size can also be separated based on subtle differences in dielectric property, by controlling the frequency of the AC current supplied to the electrodes.

  10. ACOUSTIC MONITOR FOR LIQUID-SOLID SLURRIES MEASUREMENTS AT LOW WEIGHT FRACTIONS

    EPA Science Inventory

    The principal objective of the project is to develop an acoustic probe for determining the weight fraction of particles in a flowing suspension. The suspension can be solid-liquid (S-L) or solid-gas-liquid (S-G-L). The work will include testing the theory of acoustic wave propaga...

  11. Chromatographic methods enabling the characterization of stationary phases and retention prediction in high-performance liquid chromatography and supercritical fluid chromatography.

    PubMed

    Sykora, David; Vozka, Jiri; Tesarova, Eva

    2016-01-01

    In the scope of the present review, the current status of high-performance liquid chromatography/ultra-high performance liquid chromatography and supercritical fluid chromatography is briefly provided. These techniques and their retention mechanisms are compared. Various alternative approaches utilized for the determination and description of the retention processes in these two systems are mapped. Two frequently used concepts, linear-free energy relationships, and hydrophobic subtraction models, used for the characterization of the retention interactions, are discussed. Principles and selected applications of the both methods are also covered. Then the models applied for the prediction of retention behavior of solutes on stationary phases are outlined. The procedures utilized for the sorbent/column classification are also covered. Simple chromatographic tests frequently used for the basic characterization and mutual comparison of stationary phases are summarized and briefly commented on. The importance of a statistical evaluation of complex retention data obtained from the chromatographic measurements is outlined. Finally, computer simulations aiming at the facilitation of the quest to optimize separation conditions for a given mixture of analytes are touched upon. PMID:26497150

  12. Validated Stability-indicating High-performance Liquid Chromatographic Method for Estimation of Degradation Behaviour of Eberconazole Nitrate and Mometasone Furoate in Cream Formulation.

    PubMed

    Sharma, N; Rao, S S; Vaghela, B

    2013-01-01

    The objective of current investigation was to study the degradation behaviour of eberconazole nitrate and mometasone furoate under different International Conference on harmonisation recommended stress condition using reverse phase high performance liquid chromatographic method and to establish validated stability-indicating high performance liquid chromatographic method to determine purity of eberconazole nitrate and mometasone furoate in presence of its impurities, forced degradation products and placebo in pharmaceutical dosage forms. The method was developed using Hypersil BDS, C18, 150Χ4.6 mm, 5 μ as stationary phase with mobile phase containing a gradient mixture of solvent A and B. 0.01 M phosphate buffer with 0.1% triethyl amine, adjusted pH 7.0 with phosphoric acid was used as buffer. Buffer pH 7.0 was used as solvent A and methanol:acetonitrile in 150:850 v/v ratios were used as solvent B. The eluted compounds were monitored at 240 nm. The run time was 50 min. The developed method was validated as per international conference on harmonization guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. PMID:23901164

  13. Phosphorus fractionation diagram as a quantitative indicator of crystallization differentiation of basaltic liquids

    USGS Publications Warehouse

    Anderson, A.T.; Greenland, L.P.

    1969-01-01

    Distribution factors of phosphorus (P in mineral/P in liquid) between phenocryst minerals and coexisting basaltic groundmass are: olivine (Fa20: 0.04 to 0.02; orthopyroxene (Fs20): 0.01; augite: 0.02 to 0.01; plagioclase: 0.02; ilmenite: 0.04. Because of the smallness of these distribution factors the ratio of phosphorus in the initial liquid to that in the residual liquid (phosphorus ratio) ideally equals the mass fraction of residual liquid minus 0.00 -0.04. The phosphorus ratio facilitates, therefore, quantitative comparison of the variation of major and minor elements with crystallization of basaltic liquids. A phosphorus fractionation diagram is a log-log graph of the wt. % of any chemical element or oxide vs. the phosphorus ratio. The slopes of variation curves on such a fractionation diagram approximately equal unity minus the crystal aggregate/liquid distribution factor. Knowledge of the individual mineral/liquid distribution factors makes it possible to estimate the relative proportions of crystallizing minerals from the slopes of curves on a phosphorus fractionation diagram prior to the crystallization of apatite or other phosphorus-rich mineral. This was done fairly successfully for the Alae Lava Lake, Hawaii. ?? 1969.

  14. In situ ionic liquid dispersive liquid-liquid microextraction and direct microvial insert thermal desorption for gas chromatographic determination of bisphenol compounds.

    PubMed

    Cacho, Juan Ignacio; Campillo, Natalia; Viñas, Pilar; Hernández-Córdoba, Manuel

    2016-01-01

    A new procedure based on direct insert microvial thermal desorption injection allows the direct analysis of ionic liquid extracts by gas chromatography and mass spectrometry (GC-MS). For this purpose, an in situ ionic liquid dispersive liquid-liquid microextraction (in situ IL DLLME) has been developed for the quantification of bisphenol A (BPA), bisphenol Z (BPZ) and bisphenol F (BPF). Different parameters affecting the extraction efficiency of the microextraction technique and the thermal desorption step were studied. The optimized procedure, determining the analytes as acetyl derivatives, provided detection limits of 26, 18 and 19 ng L(-1) for BPA, BPZ and BPF, respectively. The release of the three analytes from plastic containers was monitored using this newly developed analytical method. Analysis of the migration test solutions for 15 different plastic containers in daily use identified the presence of the analytes at concentrations ranging between 0.07 and 37 μg L(-1) in six of the samples studied, BPA being the most commonly found and at higher concentrations than the other analytes. PMID:26476920

  15. Concentration and fractionation of hydrophobic organic acid constituents from natural waters by liquid chromatography

    USGS Publications Warehouse

    Thurman, E.M.; Malcolm, R.L.

    1979-01-01

    A scheme is presented which used adsorption chromatography with pH gradient elution and size-exclusion chromatography to concentrate and separate hydrophobic organic acids from water. A review of chromatographic processes involved in the flow scheme is also presented. Organic analytes which appear in each aqueous fraction are quantified by dissolved organic carbon analysis. Hydrophobic organic acids in a water sample are concentrated on a porous acrylic resin. These acids usually constitute approximately 30-50 percent of the dissolved organic carbon in an unpolluted water sample and are eluted with an aqueous eluent (dilute base). The concentrate is then passed through a column of polyacryloylmorpholine gel, which separates the acids into high- and low-molecular-weight fractions. The high- and low-molecular-weight eluates are reconcentrated by adsorption chromatography, then are eluted with a pH gradient into strong acids (predominately carboxylic acids) and weak acids (predominately phenolic compounds). For standard compounds and samples of unpolluted waters, the scheme fractionates humic substances into strong and weak acid fractions that are separated from the low molecular weight acids. A new method utilizing conductivity is also presented to estimate the acidic components in the methanol fraction.

  16. Enhancing Extraction and Detection of Veterinary Antibiotics in Solid and Liquid Fractions of Manure.

    PubMed

    Wallace, Joshua S; Aga, Diana S

    2016-03-01

    Analysis of veterinary antibiotics in separated liquid and solid fractions of animal manures is vital because of wide variations in the composition of agriculturally applied manure. Differentiation of antibiotic concentrations is important between liquid and solid manures, as their sorption onto the solid fraction depends on physicochemical properties of each antibiotic and manure composition (e.g., organic content, pH) and because each fraction may be treated and reused differently. Here, an efficient and sensitive method for the analysis of 22 veterinary antibiotics in the liquid and solid fractions of manure is reported. Tetracycline (TC), macrolide, and sulfonamide antibiotics were extracted from liquid manure by liquid-liquid extraction (LLE) with methanol following acidification with acetic acid. Extraction from solids was performed by sonication with acetonitrile, methanol, and 0.1 M EDTA-McIlvaine buffer. Cleanup of extracts was achieved by solid-phase extraction with hydrophilic-lipophilic balance (HLB) cartridges or tandem amino (NH2) and HLB cartridges. Quantification of antibiotics was performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) under wrong-way-round (WWR) ionization for sulfonamides and TCs and right-way-round ionization for macrolides. Recoveries of 58 to 94.7% and 62 to 94.3% were obtained in liquid and solid manure, respectively. Method detection limits range from 1.2 to 12 ng L and 0.5 to 7.9 μg kg dry wt. in liquids and solids, respectively. This method allows for extraction and analysis of both mobile antibiotics in liquid phase and hydrophobic antibiotics adsorbed on the solids. Without separate analysis, antibiotic concentrations may be improperly estimated by analyzing whole manure, as reported in many studies to date. PMID:27065393

  17. Final Report for Fractionation and Separation of Polydisperse Nanoparticles into Distinct Monodisperse Fractions Using CO2 Expanded Liquids

    SciTech Connect

    Chistopher Roberts

    2007-08-31

    The overall objective of this project was to facilitate efficient fractionation and separation of polydisperse metal nanoparticle populations into distinct monodisperse fractions using the tunable solvent properties of gas expanded liquids. Specifically, the dispersibility of ligand-stabilized nanoparticles in an organic solution was controlled by altering the ligand-solvent interaction (solvation) by the addition of carbon dioxide (CO{sub 2}) gas as an antisolvent (thereby tailoring the bulk solvent strength) in a custom high pressure apparatus developed in our lab. This was accomplished by adjusting the CO{sub 2} pressure over the liquid dispersion, resulting in a simple means of tuning the nanoparticle precipitation by size. Overall, this work utilized the highly tunable solvent properties of organic/CO{sub 2} solvent mixtures to selectively size-separate dispersions of polydisperse nanoparticles (ranging from 1 to 20 nm in size) into monodisperse fractions ({+-}1nm). Specifically, three primary tasks were performed to meet the overall objective. Task 1 involved the investigation of the effects of various operating parameters (such as temperature, pressure, ligand length and ligand type) on the efficiency of separation and fractionation of Ag nanoparticles. In addition, a thermodynamic interaction energy model was developed to predict the dispersibility of different sized nanoparticles in the gas expanded liquids at various conditions. Task 2 involved the extension of the experimental procedures identified in task 1 to the separation of other metal particles used in catalysis such as Au as well as other materials such as semiconductor particles (e.g. CdSe). Task 3 involved using the optimal conditions identified in tasks 1 and 2 to scale up the process to handle sample sizes of greater than 1 g. An experimental system was designed to allow nanoparticles of increasingly smaller sizes to be precipitated sequentially in a vertical series of high pressure vessels by

  18. Alternative solvent-based methyl benzoate vortex-assisted dispersive liquid-liquid microextraction for the high-performance liquid chromatographic determination of benzimidazole fungicides in environmental water samples.

    PubMed

    Santaladchaiyakit, Yanawath; Srijaranai, Supalax

    2014-11-01

    Vortex-assisted dispersive liquid-liquid microextraction using methyl benzoate as an alternative extraction solvent for extracting and preconcentrating three benzimidazole fungicides (i.e., carbendazim, thiabendazole, and fluberidazole) in environmental water samples before high-performance liquid chromatographic analysis has been developed. The selected microextraction conditions were 250 μL of methyl benzoate containing 300 μL of ethanol, 1.0% w/v sodium acetate, and vortex agitation speed of 2100 rpm for 30 s. Under optimum conditions, preconcentration factors were 14.5-39.0 for the target fungicides. Limits of detection were obtained in the range of 0.01-0.05 μg/L. The proposed method was then applied to surface water samples and the recovery evaluations at three spiked concentration levels of 5, 30, and 50 μg/L were obtained in the range of 77.4-110.9% with the relative standard deviation <7.4%. The present method was simple, rapid, low cost, sensitive, environmentally friendly, and suitable for the trace analysis of the studied fungicides in environmental water samples. PMID:25156324

  19. Ultrafast Liquid Chromatographic Method Development and its Validation for Quantification of Telaprevir in Pharmaceutical Dosage Form by Using Quality by Design Approach.

    PubMed

    Panda, Sagar Suman; Bera, Venkata Varaha Ravi Kumar; Beg, Sarwar; Sahu, Sunil Kumar

    2015-08-01

    Quality by design (QbD) approach thrives to achieve an assured and predicted quality product. A stability-indicating reversed phase ultrafast liquid chromatographic method was developed using the principles of QbD to quantify telaprevir (TEL) in pharmaceutical dosage form. A Box-Behnken experimental design was employed for identifying optimum chromatographic conditions by assessing the method robustness by selecting organic phase composition (%), mobile phase flow rate (mL/min) and pH of the borate buffer as the factors, to study their effect on the responses like retention time, theoretical plate count and tailing factor. Chromatographic separation was achieved on Enable-C18G (250 × 4.6 mm i.d., 5 µm) column using methanol: borate buffer of pH 9.0 (90 : 10, v/v) as mobile phase at a flow rate of 1.2 mL/min and PDA detection at 270 nm. Establishment of calibration curve yielded linearity in the range of 5-70 µg/mL along with values of accuracy and precision within the acceptance limit of mean percent recoveries between 98.9 and 100.7%. Limit of detection and limit of quantitation were found to be 1.60 and 4.75 µg/mL. Analysis of system suitability yielded high degree of method reproducibility and robustness. The developed method showed high specificity for TEL and its degradation products formed during forced degradation conditions. The developed method also demonstrated suitability for routine analysis of TEL in bulk drug and pharmaceutical dosage forms. PMID:25644812

  20. Reversed-phase liquid chromatographic determination of two manufacturing intermediates in D&C Red No. 34 and its lakes.

    PubMed

    Harp, Bhakti Petigara; Barrows, Julie N

    2009-01-01

    A reversed-phase LC method was developed to determine two manufacturing intermediates in the monosulfo monoazo color additive D&C Red No. 34 and its lakes. The analytes are 2-amino-1-naphthalenesulfonic acid (Tobias acid) and 3-hydroxy-2-naphthalenecarboxylic acid (3-hydroxy-2-naphthoic acid). This method can be used for batch certification of the color additives by the U.S. Food and Drug Administration to ensure that each lot meets published specifications for coloring drugs and cosmetics. The new method uses lithium oxalate in methanol-water to dissolve the color additives for analysis. The analytes were identified by comparison of their LC retention times and UV absorption spectra with those of standards. Peak area calibrations were generally linear (R > 0.999) and recoveries were 105% for Tobias acid and 103% for 3-hydroxy-2-naphthoic acid. The limits of determination (LOD) were 0.01% for Tobias acid and 0.03% for 3-hydroxy-2-naphthoic acid. The RSDs at the specification levels were 0.9% for Tobias acid and 3.2% for 3-hydroxy-2-naphthoic acid. Survey analyses of 14 samples of certified D&C Red No. 34 straight colors and lakes from six domestic and foreign manufacturers yielded results for Tobias acid that generally agreed with results previously obtained by using a gravity elution column chromatographic method. Nine of the results for 3-hydroxy-2-naphthoic acid were 2 to 5 times higher than the results obtained using the column chromatographic method. We attribute the lower accuracy of the column chromatographic method to incomplete solubility of the samples using the method conditions and difficulty with interpreting the UV spectrophotometric results. PMID:20166580

  1. Lipophilicity indices derived from the liquid chromatographic behavior observed under bimodal retention conditions (reversed phase/hydrophilic interaction): application to a representative set of pyridinium oximes.

    PubMed

    Voicu, Victor; Sârbu, Costel; Tache, Florentin; Micăle, Florina; Rădulescu, Ştefan Flavian; Sakurada, Koichi; Ohta, Hikoto; Medvedovici, Andrei

    2014-05-01

    The liquid chromatographic behavior observed under bimodal retention conditions (reversed phase and hydrophilic interaction) offers a new basis for the determination of some derived lipophilicity indices. The experiments were carried out on a representative group (30 compounds) of pyridinium oximes, therapeutically tested in acetylcholinesterase reactivation, covering a large range of lipophilic character. The chromatographic behavior was observed on a mixed mode acting stationary phase, resulting from covalent functionalization of high purity spherical silica with long chain alkyl groups terminated by a polar environment created through the vicinal diol substitution at the lasting carbon atoms (Acclaim Mixed Mode HILIC 1 column). Elution was achieved by combining different proportions of 5 mM ammonium formiate solutions in water and acetonitrile. The derived lipophilicity indices were compared with logP values resulting from different computational algorithms. The correlations between experimental and computed data sets are significant. To obtain a better insight on the transition from reversed phase to hydrophilic interaction retention mechanisms, the variation of the thermodynamic parameters determined through the van׳t Hoff approach was also discussed. PMID:24720980

  2. Development and validation of a reversed-phase liquid chromatographic method for separation and simultaneous determination of COX-2 inhibitors in pharmaceuticals and its application to biological fluids.

    PubMed

    Rao, R Nageswara; Meena, S; Nagaraju, D; Rao, A Raghu Ram

    2005-06-01

    An isocratic reversed-phase high-performance liquid chromatographic method has been developed for separation and simultaneous determination of COX-2 inhibitors, viz., celecoxib, rofecoxib, valdecoxib, nimesulide and nabumetone, using 4-chloro-2-nitroaniline as internal standard. Good chromatographic separation was achieved using a reversed-phase Inertsil C(18) column with mobile phase consisting of methanol and 0.05% aqueous glacial acetic acid (68:32 v/v) using photodiode array (PDA) detector at 230 nm. It was validated with respect to accuracy, precision, linearity, limit of detection and quantification. The linearity range was found to be 1.0--20 microg/mL and the percentage recoveries were between 97.55 and 100.14. The method is suitable not only for the estimation of active ingredients in pharmaceutical dosage forms but also in vitro estimations in human plasma. It is simple, rapid, selective and capable of detecting and determining COX-2 inhibitors with a detection limit of 0.127--1.040 microg/mL simultaneously. PMID:15627281

  3. Development and validation of an high-performance liquid chromatographic, and a ultraviolet spectrophotometric method for determination of Ambroxol hydrochloride in pharmaceutical preparations.

    PubMed

    Muralidharan, Selvadurai; Kumar, Jaya Raja; Dhanara, Sokkalingam Arumugam

    2013-01-01

    A high-performance liquid chromatographic (HPLC) and ultraviolet (UV) methods were developed and validated for the quantitative determination of Ambroxol hydrochloride (AMH) in pharmaceutical dosage form. HPLC was carried out by reversed phase (RP) technique on an RP-18 column with a mobile phase composed of acetonitrile and water (pH 3.5 adjusted with orthophosphoric acid [60:40, v/v]). UV method was performed with the λmax at 250 nm. Both the methods showed good linearity, reproducibility, and precision. No spectral or chromatographic interferences from the tablet excipients were found in UV and HPLC. The method was successfully applied to commercial tablets. Validation parameters such as linearity, precision, accuracy, and specificity were determined. The HPLC Limit of detection (LOD) and Limit of quantification (LOQ) for Ambroxol were found to be 1 and 5 ng/ml, respectively. The UV LOD and LOQ for Ambroxol were found to be 1 and 4 μg/ml, respectively. The results were statistically compared using one-way analysis of variance. The proposed economical method could be applicable for routine analysis of AMH and monitoring of the quality of marketed drugs. PMID:23662284

  4. Liquid Chromatographic Method for Simultaneous Quantitation of Clopidogrel, Aspirin and Atorvastatin in Rat Plasma and Its Application to the Pharmacokinetic Study.

    PubMed

    Porwal, Pawan K; Akhalaque Ahmad, R A; Chhajed, Santosh S; Chatpalliwar, Vivekanand A

    2015-08-01

    A simple and robust analytical reversed-phase high-performance liquid chromatography method was developed and validated for simultaneous chromatographic elution of three cardiovascular drugs, namely clopidogrel, aspirin (ASP) and atorvastatin. The method was developed in rat plasma and dosage formulation with high-quality chromatographic separation between the drug peaks by using a stainless steel analytical column thermo beta-basic, C18 (25 × 0.46 cm, 5 µm). The system was operated at 25°C using a mobile phase consisting of acetonitrile and phosphate buffer (pH 3.0) in the gradient ratio at a flow rate of 1 mL min(-1) with ultraviolet detection monitored at 232 nm. The parametric statistics, i.e., correlation coefficient of 0.999, was assessed for all the drugs having linearity over the tested concentration range (10-10,000 ng mL(-1)) in rat plasma using an unweighted calibration curve. The accuracy of samples for six replicate measurements at lower limit of quantitation level was within limit. The method was applicable for the quality control of the mentioned drugs in raw material, bulk drug and pharmaceutical formulations as well as in pharmacokinetic studies. PMID:25609600

  5. Development and validation of an high-performance liquid chromatographic, and a ultraviolet spectrophotometric method for determination of Ambroxol hydrochloride in pharmaceutical preparations

    PubMed Central

    Muralidharan, Selvadurai; Kumar, Jaya Raja; Dhanara, Sokkalingam Arumugam

    2013-01-01

    A high-performance liquid chromatographic (HPLC) and ultraviolet (UV) methods were developed and validated for the quantitative determination of Ambroxol hydrochloride (AMH) in pharmaceutical dosage form. HPLC was carried out by reversed phase (RP) technique on an RP-18 column with a mobile phase composed of acetonitrile and water (pH 3.5 adjusted with orthophosphoric acid [60:40, v/v]). UV method was performed with the λmax at 250 nm. Both the methods showed good linearity, reproducibility, and precision. No spectral or chromatographic interferences from the tablet excipients were found in UV and HPLC. The method was successfully applied to commercial tablets. Validation parameters such as linearity, precision, accuracy, and specificity were determined. The HPLC Limit of detection (LOD) and Limit of quantification (LOQ) for Ambroxol were found to be 1 and 5 ng/ml, respectively. The UV LOD and LOQ for Ambroxol were found to be 1 and 4 μg/ml, respectively. The results were statistically compared using one-way analysis of variance. The proposed economical method could be applicable for routine analysis of AMH and monitoring of the quality of marketed drugs. PMID:23662284

  6. High-performance liquid chromatographic method for the determination of the anthelmintic nitroxynil in cattle muscle tissue with on-line anion-exchange clean-up.

    PubMed

    Tarbin, J A; Shearer, G

    1993-04-01

    A high-performance liquid chromatographic method for the determination of the anthelmintic nitroxynil has been developed. The drug was extracted from cattle muscle tissue with 1% triethylamine in acetonitrile. The extract was evaporated to dryness and taken up in 0.1 M ammonium acetate-acetonitrile (50:50, v/v). The extract was then injected onto a polymeric anion-exchange precolumn. After clean-up with 0.1 M ammonium acetate-acetonitrile (50:50, v/v) for 5 min, the precolumn was eluted with 1% aqueous trifluoroacetic acid-acetonitrile (50:50, v/v) onto a PLRP-S polymer column and chromatographed with a mobile phase of 0.01 M phosphate pH 7-acetonitrile (80:20, v/v). Detection was by ultraviolet at 273 nm. Average recoveries at four levels from 0.005 to 1.000 mg kg-1 were > 88%. The limit of determination was 0.005 mg kg-1. PMID:8491824

  7. A very simple high-performance liquid chromatographic method with fluorescence detection for the determination of gemifloxacin in human breast milk.

    PubMed

    Sagirli, Olcay; Demirci, Seda; Önal, Armağan

    2015-12-01

    A high-performance liquid chromatographic method with fluorescence detection was developed and validated for the determination of gemifloxacin in human breast milk. The proposed method allows the determination of gemifloxacin in breast milk samples without complex sample preparation. The samples were mixed with a mobile phase and filtered with a 0.45 µm polytetrafluoroethylene filter before analysis. Chromatographic separation was carried out on a C18 column (150 × 4.6 mm, 5 µm I.D.) using methanol:50 mM ortho-phosphoric acid solution (40:60) as the mobile phase with a 1.0 mL/min flow rate. Quantitation was performed using fluorescence detection with an excitation wavelength at 272 nm and an emission wavelength at 395 nm. The linear range was found to be 0.1-2.5 µg/mL. The method was applied successfully for the determination of gemifloxacin in breast milk obtained from a breastfeeding mother after oral administration of a single tablet that included 320 mg gemifloxacin per gemifloxacin tablet. PMID:25808579

  8. Liquid chromatographic resolution of 3-amino-1,4-benzodiazepin-2-ones on crown ether-based chiral stationary phases.

    PubMed

    Park, Je Young; Jin, Kab Bong; Hyun, Myung Ho

    2012-05-01

    3-Amino-5-phenyl (or 5-methyl)-1,4-benzodiazepin-2-ones, which are chiral precursors of anti-respiratory syncytial virus active agents, were resolved on three different chiral stationary phases (CSPs) based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid or (3,3'-diphenyl-1,1'-binaphthyl)-20-crown-6. Among the three CSPs, the CSP that is based on (3,3'-diphenyl-1,1'-binaphthyl)-20-crown-6 and containing residual silanol group-protecting n-octyl groups on the silica surface was found to be most effective with the use of 80% ethanol in water containing perchloric acid (10 mM) and ammonium acetate (1.0 mM) as a mobile phase. The separation factors (α) and resolutions (R(S) ) were in the range of 1.90-3.21 and 2.79-5.96, respectively. From the relationship between the analyte structure and the chromatographic resolution behavior, the chiral recognition mechanism on the CSP based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid was proposed to be different from that on the CSP based on (3,3'-diphenyl-1,1'-binaphthyl)-20-crown-6. In addition, the chromatographic resolution behavior of the most effective CSP was investigated as a function of the composition of aqueous mobile phase containing organic and acidic modifier and ammonium acetate. PMID:22508444

  9. Apparatus for measuring the local void fraction in a flowing liquid containing a gas

    DOEpatents

    Dunn, Patrick F.

    1981-01-01

    The local void fraction in liquid containing a gas is measured by placing an impedance-variation probe in the liquid, applying a controlled voltage or current to the probe, and measuring the probe current or voltage. A circuit for applying the one electrical parameter and measuring the other includes a feedback amplifier that minimizes the effect of probe capacitance and a digitizer to provide a clean signal. Time integration of the signal provides a measure of the void fraction, and an oscilloscope display also shows bubble size and distribution.

  10. Apparatus for measuring the local void fraction in a flowing liquid containing a gas

    DOEpatents

    Dunn, P.F.

    1979-07-17

    The local void fraction in liquid containing a gas is measured by placing an impedance-variation probe in the liquid, applying a controlled voltage or current to the probe, and measuring the probe current or voltage. A circuit for applying the one electrical parameter and measuring the other includes a feedback amplifier that minimizes the effect of probe capacitance and a digitizer to provide a clean signal. Time integration of the signal provides a measure of the void fraction, and an oscilloscope display also shows bubble size and distribution.

  11. Systematic evaluation of commercially available ultra-high performance liquid chromatography columns for drug metabolite profiling: optimization of chromatographic peak capacity.

    PubMed

    Dubbelman, Anne-Charlotte; Cuyckens, Filip; Dillen, Lieve; Gross, Gerhard; Hankemeier, Thomas; Vreeken, Rob J

    2014-12-29

    The present study investigated the practical use of modern ultra-high performance liquid chromatography (UHPLC) separation techniques for drug metabolite profiling, aiming to develop a widely applicable, high-throughput, easy-to-use chromatographic method, with a high chromatographic resolution to accommodate simultaneous qualitative and quantitative analysis of small-molecule drugs and metabolites in biological matrices. To this end, first the UHPLC system volume and variance were evaluated. Then, a mixture of 17 drugs and various metabolites (molecular mass of 151-749Da, logP of -1.04 to 6.7), was injected on six sub-2μm particle columns. Five newest generation core shell technology columns were compared and tested against one column packed with porous particles. Two aqueous (pH 2.7 and 6.8) and two organic mobile phases were evaluated, first with the same flow and temperature and subsequently at each column's individual limit of temperature and pressure. The results demonstrated that pre-column dead volume had negligible influence on the peak capacity and shape. In contrast, a decrease in post-column volume of 57% resulted in a substantial (47%) increase in median peak capacity and significantly improved peak shape. When the various combinations of stationary and mobile phases were used at the same flow rate (0.5mL/min) and temperature (45°C), limited differences were observed between the median peak capacities, with a maximum of 26%. At higher flow though (up to 0.9mL/min), a maximum difference of almost 40% in median peak capacity was found between columns. The finally selected combination of solid-core particle column and mobile phase composition was chosen for its selectivity, peak capacity, wide applicability and peak shape. The developed method was applied to rat hepatocyte samples incubated with the drug buspirone and demonstrated to provide a similar chromatographic resolution, but a 6 times higher signal-to-noise ratio than a more traditional UHPLC

  12. FINGERPRINTING INORGANIC ARSENIC AND ORGANOARSENIC COMPOUNDS IN IN SITU OIL SHALE RETORT AND PROCESS VOTERS USING A LIQUID CHROMATOGRAPH COUPLED WITH AN ATOMIC ABSORPTION SPECTROMETER AS A DETECTOR

    SciTech Connect

    Fish, Richard H.; Brinckman, Frederick E.; Jewett, Kenneth L.

    1981-07-01

    Inorganic arsenic and organoarsenic compounds were speciated in seven oil shale retort and process waters, including samples from simulated, true and modified in situ processes, using a high performance liquid chromatograph automatically coupled to a graphite furnace atomic absorption detector. The molecular forms of arsenic at ppm levels (({micro}g/mL) in these waters are identified for the first time, and shown to include arsenate, methylarsonic acid and phenylarsonic acid. An arsenic-specific fingerprint chromatogram of each retort or process water studied has significant impliestions regarding those arsenical species found and those marginally detected, such as dimethylarsinic acid and the suspected carcinogen arsenite. The method demonstrated suggests future means for quantifying environmental impacts of bioactive organometal species involved in oil shale retorting technology.

  13. High-performance liquid chromatographic method for rapid and highly sensitive determination of histidine using postcolumn fluorescence detection with o-phthaldialdehyde.

    PubMed

    Tateda, N; Matsuhisa, K; Hasebe, K; Kitajima, N; Miura, T

    1998-11-01

    A high-performance liquid chromatographic method was developed for the rapid and sensitive determination of histidine. The method is based on separation by reversed-phase ion-pair chromatography followed by highly selective fluorescence derivatization of histidine with o-phthaldialdehyde. A linear calibration curve was obtained over the range of 0.25-200 pmol per injection (10 microl) with the coefficient of variation of 0.9% at 2 pmol (n=10) and with the detection limit (SIN=8) of 25 fmol. The method was applicable to the assay of histidine in human serum. Serum histidine values obtained by the present method were in good agreement with values obtained with an amino acid analyzer. PMID:9840433

  14. Reversed-phase high-performance liquid chromatographic approach to determine total lymphocyte concentrations of 6-thioguanine, methylmercaptopurine and methylthioguanine in humans.

    PubMed

    Erdmann, G R; Steury, J C; Carleton, B C; Stafford, R J; Bostrom, B C; Canafax, D M

    1991-11-15

    A reversed-phase high-performance liquid chromatographic (HPLC) procedure was developed to quantify intracellular lymphocyte 6-thioguanine, methylmercaptopurine and methylthioguanine. The free base of each metabolite was obtained by acid hydrolysis, which allowed for a total determination of thiopurine metabolites. 6-Thioguanine was analyzed on an octadecylsilane column using acetonitrile-10 mM sodium phosphate (11:89), pH 7, containing 0.06% tetrabutylammonium chloride. 6-Thioguanine was oxidized with potassium permanganate, and fluorescence was measured at 330 nm excitation and 410 nm emission. Methylmercaptopurine and methylthioguanine were separated on a cyanopropylsilane column using methanol-40 mM sodium phosphate (22:78), pH 2.7, and detected by ultraviolet absorbance at 314 and 290 nm, respectively. PMID:1810943

  15. Nanofluid of zinc oxide nanoparticles in ionic liquid for single drop liquid microextraction of fungicides in environmental waters prior to high performance liquid chromatographic analysis.

    PubMed

    Amde, Meseret; Tan, Zhi-Qiang; Liu, Rui; Liu, Jing-Fu

    2015-05-22

    Using a nanofluid obtained by dispersing ZnO nanoparticles (ZnO NPs) in 1-hexyl-3-methylimidazolium hexafluorophosphate, new single drop microextraction method was developed for simultaneous extraction of three fungicides (chlorothalonil, kresoxim-methyl and famoxadone) in water samples prior to their analysis by high performance liquid chromatography (HPLC-VWD). The parameters affecting the extraction efficiency such as amount of ZnO NPs in the nanofluid, solvent volume, extraction time, stirring rate, pH and ionic strength of the sample solution were optimized. Under the optimized conditions, the limits of detection were in the range of 0.13-0.19ng/mL, the precision of the method assessed with intra-day and inter-day relative standard deviations were <4.82% and <7.04%, respectively. The proposed method was successfully applied to determine the three fungicides in real water samples including lake water, river water, as well as effluent and influent of wastewater treatment plant, with recoveries in the range of 74.94-96.11% at 5ng/mL spiking level. Besides to being environmental friendly, the high enrichment factor and the data quality obtained with the proposed method demonstrated its potential for application in multi residue analysis of fungicides in actual water samples. PMID:25857539

  16. Analysis of time-fractional hunter-saxton equation: a model of neumatic liquid crystal

    NASA Astrophysics Data System (ADS)

    Atangana, Abdon; Baleanu, Dumitru; Alsaedi, Ahmed

    2016-04-01

    In this work, a theoretical study of diffusion of neumatic liquid crystals was done using the concept of fractional order derivative. This version of fractional derivative is very easy to handle and obey to almost all the properties satisfied by the conventional Newtonian concept of derivative. The mathematical equation underpinning this physical phenomenon was solved analytically via the so-called homotopy decomposition method. In order to show the accuracy of this iteration method, we constructed a Hilbert space in which we proved its stability for the time-fractional Hunder-Saxton equation.

  17. Measurement of Water Fraction in Liquid Hydro-Carbons Using ECT Sensor

    NASA Astrophysics Data System (ADS)

    Bukhari, Syed Faisal Ahmed; Ismail, Idris; Yang, Wuqiang

    2007-06-01

    In the oil industry, it is important to measure the water fraction in liquid hydrocarbons in oil pipelines for optimising operation and transportation, e.g. loading/unloading of oil tankers, where the flow rate is variable. As a feasibility study an electrical capacitance tomography (ECT) sensor has been used for on-line water fraction measurement. Data from different electrode combinations, e.g. adjacent electrodes and opposite electrodes are combined. Preliminary results indicate that ECT can be used for measuring the fraction of water in oil with 0.05% error in a range of water-in-oil up to 10%.

  18. Ultra-high performance liquid chromatographic determination of levofloxacin in human plasma and prostate tissue with use of experimental design optimization procedures.

    PubMed

    Szerkus, O; Jacyna, J; Wiczling, P; Gibas, A; Sieczkowski, M; Siluk, D; Matuszewski, M; Kaliszan, R; Markuszewski, M J

    2016-09-01

    Fluoroquinolones are considered as gold standard for the prevention of bacterial infections after transrectal ultrasound guided prostate biopsy. However, recent studies reported that fluoroquinolone- resistant bacterial strains are responsible for gradually increasing number of infections after transrectal prostate biopsy. In daily clinical practice, antibacterial efficacy is evaluated only in vitro, by measuring the reaction of bacteria with an antimicrobial agent in culture media (i.e. calculation of minimal inhibitory concentration). Such approach, however, has no relation to the treated tissue characteristics and might be highly misleading. Thus, the objective of this study was to develop, with the use of Design of Experiments approach, a reliable, specific and sensitive ultra-high performance liquid chromatography- diode array detection method for the quantitative analysis of levofloxacin in plasma and prostate tissue samples obtained from patients undergoing prostate biopsy. Moreover, correlation study between concentrations observed in plasma samples vs prostatic tissue samples was performed, resulting in better understanding, evaluation and optimization of the fluoroquinolone-based antimicrobial prophylaxis during transrectal ultrasound guided prostate biopsy. Box-Behnken design was employed to optimize chromatographic conditions of the isocratic elution program in order to obtain desirable retention time, peak symmetry and resolution of levofloxacine and ciprofloxacine (internal standard) peaks. Fractional Factorial design 2(4-1) with four center points was used for screening of significant factors affecting levofloxacin extraction from the prostatic tissue. Due to the limited number of tissue samples the prostatic sample preparation procedure was further optimized using Central Composite design. Design of Experiments approach was also utilized for evaluation of parameter robustness. The method was found linear over the range of 0.030-10μg/mL for human

  19. Thermal pretreatments of superficially porous silica particles for high-performance liquid chromatography: Surface control, structural characterization and chromatographic evaluation.

    PubMed

    Mignot, Mélanie; Sebban, Muriel; Tchapla, Alain; Mercier, Olivier; Cardinael, Pascal; Peulon-Agasse, Valérie

    2015-11-01

    This study reports the impact of thermal pretreatment between 400 and 1100°C on superficially porous silica particles (e.g. core-shell, fused-core; here abbreviated as SPP silica). The different thermally pretreated SPP silica (400°C, 900°C and 1100°C) were chemically bonded with an octadecyl chain under microwave irradiation. The bare SPP silica, thermally untreated and pretreated, as well as the chemically bonded phases (CBPs) were fully characterized by elemental analysis, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), and solid state cross polarization magic angle spinning (CP-MAS) (29)Si NMR. The chromatographic properties of the overall set of C18-thermally pretreated SPP silica stationary phases were determined using the Tanaka test. Complementary, the simplified Veuthey test was used to deeply study the silanol activity, considering a set of 7 basic solutes with various physicochemical properties. Both tests were also performed on different commercial SPP silica columns and different types of bonding chemistry (C18, Phenyl-hexyl, RP-amide, C30, aQ). Multivariate data analyses (hierarchical cluster analysis and principal component analysis) were carried out to define groups of stationary phases with similar chromatographic properties and situate them in relation to those commercially available. These different C18-thermally pretreated SPP silicas represented a wide range of stationary phases as they were spread out along the score plot. Moreover, this study highlighted that the thermal pretreatment improved the chemical stability of the SPP silica compare to untreated SPP silica and untreated porous silica. Consequently, higher thermal pretreatment can be applied (up to 900°C) before functionalization without destruction of the silica matrix. Indeed, a significantly lower dissolution of the thermally pretreated SPP silica under aggressive conditions could allow the use of the corresponding functionalized stationary phases at high

  20. Chromatographic methods for the isolation, separation and characterisation of dissolved organic matter.

    PubMed

    Sandron, Sara; Rojas, Alfonso; Wilson, Richard; Davies, Noel W; Haddad, Paul R; Shellie, Robert A; Nesterenko, Pavel N; Kelleher, Brian P; Paull, Brett

    2015-09-01

    This review presents an overview of the separation techniques applied to the complex challenge of dissolved organic matter characterisation. The review discusses methods for isolation of dissolved organic matter from natural waters, and the range of separation techniques used to further fractionate this complex material. The review covers both liquid and gas chromatographic techniques, in their various modes, and electrophoretic based approaches. For each, the challenges that the separation and fractionation of such an immensely complex sample poses is critically reviewed. PMID:26290053

  1. Rapid differentiation of Ralstonia solanacearum avirulent and virulent strains by cell fractioning of an isolate using high performance liquid chromatography.

    PubMed

    Zheng, Xuefang; Zhu, Yujing; Liu, Bo; Yu, Qian; Lin, Naiquan

    2016-01-01

    Ralstonia solanacearum is one of the most destructive plant bacterial pathogens worldwide. The population dynamics and genetic stability are important issues, especially when an avirulent strain is used for biocontrol. In this study, we developed a rapid method to differentiate the virulent and avirulent strains of R. solanacearum and to predict the biocontrol efficiency of an avirulent strain using high performance liquid chromatography (HPLC). Three chromatographic peaks P1, P2 and P3 were observed on the HPLC spectra among 68 avirulent and 28 virulent R. solanacearum strains. Based on the HPLC peaks, 96 strains total were assigned to three categories. For avirulent strains, the intense peak is P1, while for virulent strains, P3 is the majority. Based on the HLPC spectra of R. solanacearum strains, a chromatography titer index (CTI) was established as CTIi = Si/(S1+S2+S3) × 100% (i represents an individual HPLC peak; S1, S2 and S3 represent peak areas of P1, P2 and P3, respectively). The avirulent strains had high values of CTI1 ranging from 63.6 to 100.0%, while the virulent strains displayed high values of CTI3 ranging from 90.2 to 100.0%. Biological inoculation studies of 68 avirulent strains revealed that the biocontrol efficacy was the best when CTI1 = 100%. The purity and genetic stability of R. solanacearum strains were confirmed in the P1 fraction of avirulent strain FJAT-1957 and P3 fraction of virulent strain FJAT-1925 after 30 generations of consecutive subculture. These results confirmed that fractioning by HPLC and their deduced CTI can be used for rapid and efficient evaluation and prediction of an isolate of R. solanacearum. To the best of our knowledge, this is the first report that HPLC fractioning can be used for rapid differentiation of virulent and avirulent strains of R. solanacearum. PMID:26606869

  2. Anaerobic digestion of acidified slurry fractions derived from different solid-liquid separation methods.

    PubMed

    Sutaryo, Sutaryo; Ward, Alastair James; Møller, Henrik Bjarne

    2013-02-01

    Batch assays investigating the ultimate methane yields (B(0)) of acidified slurry fractions produced with different solid-liquid slurry separation techniques were done. The result showed that the anaerobic digestion (AD) process was inhibited when raw and liquid fractions of sow, pig and dairy cow acidified slurry are digested, but AD treating solid fractions (SF) acidified slurry showed no sulphide inhibition. The B(0) of SF acidified sow slurry increased significantly with increasing screen size in the screw press. No significant effect of acidification processes on B(0) of SF dairy cow slurry (DCS) was observed. The ultimate methane yields of SF acidified DCS and SF non acidified DCS were 278±13 and 289±1LkgVS(-1), while in term of fresh weigh substrate were 59±2.8 and 59±0.3Lkgsubstrate(-1), respectively. PMID:23313767

  3. Thermal conductivity of simple liquids: Origin of temperature and packing fraction dependences

    NASA Astrophysics Data System (ADS)

    Ishii, Yoshiki; Sato, Keisuke; Salanne, Mathieu; Madden, Paul A.; Ohtori, Norikazu

    2014-03-01

    The origin of both weak temperature dependence and packing fraction dependence of T1/4η3/2 in the thermal conductivity of the simple Lennard-Jones (LJ) liquid is explored. In order to discuss the relative contributions from attractive or repulsive part of the interaction potential separately, the thermal conductivity of a series of Weeks-Chandler-Anderson (WCA) fluids is calculated by molecular dynamics simulations. The results show that the repulsive part plays the main role in the heat conduction, while the attractive part has no direct effect on the thermal conductivity for a given packing fraction. By investigating WCA fluids with potentials of varying softness, we explain the difference observed between the LJ liquids such as argon and Coulombic liquids such as NaCl.

  4. High performance liquid chromatographic measurement of iothalamate in human serum and urine for evaluation of glomerular filtration rate.

    PubMed

    Bi, Daoqin; Leary, Kevin J; Weitz, Julie A; Cherstniakova, Svetlana A; Reil, Michael A; Roy, Michael J; Cantilena, Louis R

    2007-09-01

    A simple and sensitive HPLC-UV assay was developed for the measurement of iothalamate (IOT) in human serum and urine. Chromatographic separation was achieved using an embedded-carbamate-group bonded RP18 column and mobile phase consisting of 50 mM monobasic sodium phosphate and methanol (90:10, v/v) without the addition of ion-pair reagents. The assay demonstrated a high analytical reliability within the IOT concentration range of 1-150 microg/ml in serum and 25-1500 microg/ml in urine. The relative standard deviations (RSDs) for intra- and inter-day analysis were less than 5.1% in all cases. This method has been used for the evaluation of glomerular filtration rate (GFR) in subjects participating in a phase I clinical trial of a novel antimalarial medicine. The average baseline GFR was 100.41+/-19.99 ml/min/1.73 m(2) in 119 healthy volunteers. The assay may also allow the simultaneous measurements of p-aminohippuric acid (PAH), N-acetyl PAH (aPAH), and IOT with some modification. PAH, IOT, aPAH, and beta-hydroxyethyl-theophylline internal standard peaks appeared approximately at 2.5, 3.7, 5.9, and 11.8 min, respectively, in an isocratic run. PMID:17599846

  5. A Stability-indicating High Performance Liquid Chromatographic Assay for the Simultaneous Determination of Atenolol and Lercanidipine Hydrochloride in Tablets

    PubMed Central

    Kaila, H. O.; Ambasana, M. A.; Thakkar, R. S.; Saravaia, H. T.; Shah, A. K.

    2011-01-01

    A simple, rapid, precise and accurate isocratic reversed phase stability indicating HPLC method was developed and validated for the simultaneous determination of atenolol and lercanidipine hydrochloride in commercial tablets. The chromatographic separation was achieved on phenomenex Gemini C18 (250×4.6 mm, 5 μm) column using a mobile phase consisting of acetonitrile and buffer (20 mM potassium dihydrogen phosphate pH 3.5) in the ratio of (55:45, v/v) at a flow rate of 1.0 ml/min and UV detection at 235 nm. The linearity of the proposed method was investigated in the range of 40-160 μg/ml (r2=0.9995) for atenolol and 8-32 μg/ml (r2=0.9993) for lercanidipine. Degradation products produced as a result of stress studies did not interfere with the detection of atenolol and lercanidipine and the assay can thus be considered stability-indicating. PMID:22707819

  6. Development of liquid chromatographic enantiomer separation methods and validation for the estimation of (R)-enantiomer in eslicarbazepine acetate.

    PubMed

    Mone, Mahesh Kumar; Chandrasekhar, K B

    2011-01-01

    Chiral separation method development was carried out for eslicarbazepine acetate and its (R)-enantiomer on diverse chiral stationary phases. Better chiral selectivity was observed on cellulose tris-(3,5-dichlorophenylcarbamate) immobilized column (Chiralpak IC-3). Under polar organic mode (POM), with 100% acetonitrile as mobile phase and 0.5 ml/min flow, a resolution close to three was achieved. With normal phase (NP) mobile phase consisting dichloromethane:ethanol (90:10, v/v) and 1.0 ml/min flow, a resolution close to six was achieved. Detection was done by UV at 220 and 240 nm respectively. Both the methods were found to be robust and were validated with respect to robustness, precision, linearity, limit of detection, limit of quantification and accuracy. The proposed methods are suitable for the accurate estimation of (R)-enantiomer in bulk drug samples up to 0.1% when a 1mg/ml analyte test solution is chromatographed. PMID:20832962

  7. Determination of piceid in rat plasma and tissues by high-performance liquid chromatographic method with UV detection.

    PubMed

    Lv, Chunyan; Zhang, Lantong; Wang, Qiao; Liu, Weina; Wang, Chunying; Jing, Xiujuan; Liu, Yang

    2006-11-01

    A rapid, sensitive and selective HPLC method was developed and validated for determination of piceid in rat plasma and tissues. The drug was isolated from plasma and tissues by a simple protein precipitation procedure. Chromatographic separation was performed on a C(18) column with acetonitrile-water (26:74, v/v) as mobile phase. The method was successfully applied to the pharmacokinetics and tissue distribution research after oral administration of a 50 mg/kg dose of piceid to healthy male Wistar rats. The pharmacokinetic parameters showed that piceid was quickly absorbed, distributed and eliminated within 4 h after oral administration. The tissue distribution results showed that, at 10 min, the concentrations of piceid in most tissues reached peak level except in heart and testis. The highest level of piceid was found in stomach, then in small intestine, spleen, lung, brain, testis, liver, kidney and heart. The amount of piceid in testis and heart reached the peak level at 30 min. At 120 min, the amount of piceid in all tissues decreased to a low percentage of the initial concentration. Piceid was absorbed throughout the gastrointestinal tract with considerable absorption taking place in the stomach and small intestine. There was no long-term accumulation of piceid in rat tissues. PMID:16883546

  8. High-performance liquid chromatographic method for the quantification of Mitragyna inermis alkaloids in order to perform pharmacokinetic studies.

    PubMed

    Sinou, Veronique; Fiot, Julien; Taudon, Nicolas; Mosnier, Joël; Martelloni, Maryse; Bun, Sok S; Parzy, Daniel; Ollivier, Evelyne

    2010-06-01

    In Africa, Mitragyna inermis (Willd.) O. Kuntze (Rubiaceae) is commonly used in traditional medicine to treat malaria. Antimalarial activity is mostly due to the hydromethanolic extract of M. inermis leaves and especially to the main alkaloids, uncarine D and isorhynchophilline. In the present study, we describe for the first time an HPLC method for the simultaneous quantification of uncarine D and isorhynchophylline in biological matrices. SPE was used to extract the components and the internal standard naphthalene from human and pig plasma samples. Chromatographic separation was performed on a C-18 reversed column at a flow rate of 1 mL/min, using methanol-phosphate buffer (10:90, pH 7), as a mobile phase. Good linearity was observed over the concentration ranges of 0.0662-3.31 microg/mL for uncarine D and 0.0476-2.38 microg/mL for isorynchophylline. The precision was less than 12% and the accuracy was from 86 to 107% without any discrepancy between the two species. Uncarine D and isorhynchophylline recoveries were over 80%. These results allowed the quantification of both uncarine D and isorhynchophylline in pig plasma after intravenous administration of M. inermis extract. PMID:20437411

  9. Sensitive high-performance liquid chromatographic method for profiling phytoestrogens using coulometric electrode array detection: application to plasma analysis.

    PubMed

    Nurmi, T; Adlercreutz, H

    1999-10-01

    An HPLC method for profiling 13 phytoestrogens and their metabolites using coulometric electrode array detection was developed. Sensitivity of the method was slightly less than that of our GC-MS method, but significantly higher compared to the HPLC methods using diode-array or UV detection. Detection limits varied from 3.4 (secoisolariciresinol) to 40.3 (genistin) pg on column. Signal linearities ranged from the detection limits to 61 ng on column. Resolution values for the peak pairs varied from 1.1 (O-desmethylangolensin-anhydrosecoisolariciresinol) to 16 (daidzin-genistin). Intra- and interassay retention time variations were negligible and detector response variation was eliminated by frequent calibration. Chromatographic method was applied to plasma analyses and 6 of the 13 compounds were detected. Method accuracy for those six analytes varied from 69% (enterodiol) to 118% (genistein). Intraassay precision CVs ranged from 1.5% (enterolactone, 12.4 nmol/liter) to 14% (genistein, 245 nmol/liter) and interassay precision CVs ranged from 9.9% (daidzein, 67.4 nmol/liter) to 44% (enterodiol, 1.20 nmol/liter). PMID:10527503

  10. Development and validation of a stability-indicating reverse phase ultra performance liquid chromatographic method for the estimation of nebivolol impurities in active pharmaceutical ingredients and pharmaceutical formulation.

    PubMed

    Thummala, Veera Raghava Raju; Lanka, Mohana Krishna

    2015-10-01

    A sensitive, stability-indicating gradient reverse phase ultra performance liquid chromatographic method has been developed for the quantitative estimation of nebivolol impurities in active pharmaceutical ingredient (API) and pharmaceutical formulation. Efficient chromatographic separation was achieved on an Acquity BEH C18 column (100 mm x 2.1 mm, 1.7 μm) with mobile phase of a gradient mixture. The flow rate of the mobile phase was 0.18 mL/min with column temperature of 30 degrees C and detection wavelength of 281 nm. The relative response factor values of (R*)-2-( benzylamino)-1-((S*)-6-fluorochroman-2-yl) ethanol ((R x S*) NBV-), (R)-1-((R)-6-fluorochroman-2-yl)-2-((S)-2-((S)-6-fluoro-chroman-2-yl)-2-hydroxyethyl-amino) ethanol ((RRSS) NBV-3), 1-(chroman-2-yl)-2-(2-(6-fluorochroman-2-yl)-2-hydroxyethyl amino) ethanol (monodesfluoro impurity), (S)-1-((R)-6-fluorochroman-2-yl)-2-((R)-2 (S*)-6-fluoro-chroman-2-yl)-2-hydroxyethylamino) ethanol hydrochloride ((RSRS) NBV-3) and (R*)-1-((S*)-6-fluorochroman-2-yl)-2-((S*)-2-((S*)-6-fluoro-chroman-2-yl)-2-hydroxyethylamino) ethanol ((R* S* S* S*) NBV-2) were 0.65, 0.91, 0.68, 0.92 and 0.91 respectively. Nebivolol formulation sample was subjected to the stress conditions of acid, base, oxidative, hydrolytic, thermal, humidity and photolytic degradation. Nebivolol was found to degrade significantly under peroxide stress condition. The degradation products were well resolved from nebivolol and its impurities. The peak purity test results confirmed that the nebivolol peak was homogenous and pure in all stress samples and the mass balance was found to be more than 98%, thus proving the stability-indicating power of the method. The developed method was validated according to International Conference on Hormonization (ICH) guidelines with respect to specificity, linearity, limits of detection and quantification, accuracy, precision and robustness. PMID:26930962

  11. A new direct laser photo-induced fluorescence method coupled on-line with liquid chromatographic separation for the simultaneous determination of anilides pesticides.

    PubMed

    Mbaye, O M A; Maroto, A; Gaye-Seye, M D; Stephan, L; Deschamps, L; Aaron, J J; Giamarchi, P

    2015-01-01

    A new direct laser photo-induced fluorescence high performance liquid chromatography (DL-PIF-HPLC) method is developed for the simultaneous determination of three anilide pesticides, namely carboxin, monalide and propanil. DL-PIF-HPLC uses a tunable Nd:YAG-OPO laser to obtain fluorescent photoproduct(s) and to simultaneously analyze their fluorescence in a short acquisition time with an intensified CCD camera, which improves the selectivity (by choosing the suitable excitation wavelength), increases the sensitivity (due to the high energy of the laser beam) and reduces the time of analysis, relative to the classical PIF methods. However, one of the main drawbacks of PIF methods is the presence of interferences with other compounds, such as other pesticides from the same group yielding similar fluorescent photoproducts, which reduces their selectivity. The analytical interest of DL-PIF-HPLC to avoid these interferences is demonstrated. The DL-PIF spectra, chromatographic conditions and analytical performances of DL-PIF-HPLC are presented for the simultaneous determination of three anilide pesticides. The calibration curves are linear over one order of magnitude and the limits of detection are in the ng mL(-1) range. The new DL-PIF-HPLC system has the advantage to combine the performances of both techniques, DL-PIF and liquid chromatography, and to improve the analysis selectivity. PMID:25476396

  12. Binary chromatographic fingerprinting for quality evaluation of Radix Ophiopogonis by high-performance liquid chromatography coupled with ultraviolet and evaporative light-scattering detectors.

    PubMed

    Liu, Li; Lu, Yun; Shao, Qing; Cheng, Yi-Yu; Qu, Hai-Bin

    2007-11-01

    Radix Ophiopogonis is a widely used traditional Chinese medicine. The quality of Radix Ophiopogonis available in the market varies, and some confusing or fake herbs exist. In order to improve the quality control of Radix Ophiopogonis, a novel fingerprinting method was established using HPLC coupled with UV and evaporative light-scattering detectors (ELSDs). Extraction with methanol and liquid-liquid extraction with water-saturated n-butanol were employed for the preparation of the sample solution. Chromatographic separation was performed on a Lichrospher C(18) column (250x4.6 mm id, 5.0 microm particle size) with a linear gradient elution program. UV detection at 280 nm and evaporative light-scattering detection were utilized to obtain two subfingerprinting chromatograms. A novel protocol for data processing was proposed, in order to identify and remove redundant data obtained by the two detectors, and balance the weight of the two subfingerprints on the similarity values. The method was validated and applied to quality evaluation of 16 samples of Radix Ophiopogonis and related herbs. PMID:17874416

  13. A bridging study for oxytetracycline in the edible fillet of rainbow trout: Analysis by a liquid chromatographic method and the official microbial inhibition assay

    USGS Publications Warehouse

    Stehly, G.R.; Gingerich, W.H.; Kiessling, C.R.; Cutting, J.H.

    1999-01-01

    Oxytetracycline (OTC) is a drug approved by the U.S. Food and Drug Administration (FDA) to control certain diseases in salmonids and catfish. OTC is also a likely control agent for diseases of other fish species and for other diseases of salmonids and catfish not currently on the label. One requirement for FDA to extend and expand the approval of this antibacterial agent to other fish species is residue depletion studies. The current regulatory method for OTC in fish tissue, based on microbial inhibition, lacks sensitivity and specificity. To conduct residue depletion studies for OTC in fish with a liquid chromatographic method, a bridging study was required to determine its relationship with the official microbial inhibition assay. Triplicate samples of rainbow trout fillet tissue fortified with OTC at 0.3, 0.6, 1.2, 2.4, 4.8, and 9.6 ppm and fillet tissue with incurred OTC at approximately 0.75, 1.5, and 3.75 ppm were analyzed by high-performance liquid chromatography (HPLC) and the microbial inhibition assay. The results indicated that the 2 methods are essentially identical in the tested range, with mean coefficients of variation of 1.05% for the HPLC method and 3.94% for the microbial inhibition assay.

  14. Catalytic two-stage coal hydrogenation process using extinction recycle of heavy liquid fraction

    DOEpatents

    MacArthur, James B.; Comolli, Alfred G.; McLean, Joseph B.

    1989-01-01

    A process for catalytic two-stage hydrogenation and liquefaction of coal with selective extinction recycle of all heavy liquid fractions boiling above a distillation cut point of about 600.degree.-750.degree. F. to produce increased yields of low-boiling hydrocarbon liquid and gas products. In the process, the particulate coal feed is slurried with a process-derived liquid solvent normally boiling above about 650.degree. F. and fed into a first stage catalytic reaction zone operated at conditions which promote controlled rate liquefaction of the coal, while simultaneously hydrogenating the hydrocarbon recycle oils. The first stage reactor is maintained at 710.degree.-800.degree. F. temperature, 1000-4000 psig hydrogen partial pressure, and 10-90 lb/hr per ft.sup.3 catalyst space velocity. Partially hydrogenated material withdrawn from the first stage reaction zone is passed directly to the second stage catalytic reaction zone maintained at 760.degree.-860.degree. F. temperature for further hydrogenation and hydroconversion reactions. A 600.degree.-750.degree. F..sup.+ fraction containing 0-20 W % unreacted coal and ash solids is recycled to the coal slurrying step. If desired, the cut point lower boiling fraction can be further catalytically hydrotreated. By this process, the coal feed is successively catalytically hydrogenated and hydroconverted at selected conditions, to provide significantly increased yields of desirable low-boiling hydrocarbon liquid products and minimal production of hydrocarbon gases, and no net production of undesirable heavy oils and residuum materials.

  15. Catalytic two-stage coal hydrogenation process using extinction recycle of heavy liquid fraction

    DOEpatents

    MacArthur, J.B.; Comolli, A.G.; McLean, J.B.

    1989-10-17

    A process is described for catalytic two-stage hydrogenation and liquefaction of coal with selective extinction recycle of all heavy liquid fractions boiling above a distillation cut point of about 600--750 F to produce increased yields of low-boiling hydrocarbon liquid and gas products. In the process, the particulate coal feed is slurried with a process-derived liquid solvent normally boiling above about 650 F and fed into a first stage catalytic reaction zone operated at conditions which promote controlled rate liquefaction of the coal, while simultaneously hydrogenating the hydrocarbon recycle oils. The first stage reactor is maintained at 710--800 F temperature, 1,000--4,000 psig hydrogen partial pressure, and 10-90 lb/hr per ft[sup 3] catalyst space velocity. Partially hydrogenated material withdrawn from the first stage reaction zone is passed directly to the second stage catalytic reaction zone maintained at 760--860 F temperature for further hydrogenation and hydroconversion reactions. A 600--750 F[sup +] fraction containing 0--20 W % unreacted coal and ash solids is recycled to the coal slurrying step. If desired, the cut point lower boiling fraction can be further catalytically hydrotreated. By this process, the coal feed is successively catalytically hydrogenated and hydroconverted at selected conditions, to provide significantly increased yields of desirable low-boiling hydrocarbon liquid products and minimal production of hydrocarbon gases, and no net production of undesirable heavy oils and residuum materials. 2 figs.

  16. Method development for liquid chromatographic/triple quadrupole mass spectrometric analysis of trace level perfluorocarboxylic acids in articles of commerce

    EPA Science Inventory

    An analytical method to identify and quantify trace levels of C5 to C12 perfluorocarboxylic acids (PFCAs) in articles of commerce (AOC) is developed and rigorously validated. Solid samples were extracted in methanol, and liquid samples were diluted with a solvent consisting of 60...

  17. Experimental evidence for Mo isotope fractionation between metal and silicate liquids

    NASA Astrophysics Data System (ADS)

    Hin, Remco C.; Burkhardt, Christoph; Schmidt, Max W.; Bourdon, Bernard; Kleine, Thorsten

    2013-10-01

    Stable isotope fractionation of siderophile elements may inform on the conditions and chemical consequences of core-mantle differentiation in planetary objects. The extent to which Mo isotopes fractionate during such metal-silicate segregation, however, is so far unexplored. We have therefore investigated equilibrium fractionation of Mo isotopes between liquid metal and liquid silicate to evaluate the potential of Mo isotopes as a new tool to study core formation. We have performed experiments at 1400 and 1600 °C in a centrifuging piston cylinder. Tin was used to lower the melting temperature of the Fe-based metal alloys to <1400 °C, while variable Fe-oxide contents were used to vary oxygen fugacity in graphite and MgO capsules. Isotopic analyses were performed using a double spike technique. In experiments performed at 1400 °C, the 98Mo/95Mo ratio of silicate is 0.19±0.03‰ (95% confidence interval) heavier than that of metal. This fractionation is not significantly affected by the presence or absence of carbon. Molybdenum isotope fractionation is furthermore independent of oxygen fugacity in the range IW -1.79 to IW +0.47, which are plausible values for core formation. Experiments at 1600 °C show that, at equilibrium, the 98Mo/95Mo ratio of silicate is 0.12±0.02‰ heavier than that of metal and that the presence or absence of Sn does not affect this fractionation. Equilibrium Mo isotope fractionation between liquid metal and liquid silicate as a function of temperature can therefore be described as ΔMoMetal-Silicate98/95=-4.70(±0.59)×105/T2. Our experiments show that Mo isotope fractionation may be resolvable up to metal-silicate equilibration temperatures of about 2500 °C, rendering Mo isotopes a novel tool to investigate the conditions of core formation in objects ranging from planetesimals to Earth sized bodies.

  18. Two high performance liquid chromatographic methods for the determination of alpha-tocopherol in serum compared to isotope dilution-gas chromatography-mass spectrometry.

    PubMed

    Kock, R; Seitz, S; Delvoux, B; Greiling, H

    1997-05-01

    Two high performance liquid chromatographic methods (HPLC) with isocratic reversed-phase separation are presented for the determination of alpha-tocopherol (vitamin E) in serum. In the first method alpha-tocopherol acetate is used as internal standard, detection of absorbance is performed at 284 nm. In the second method tocol is used as internal standard, detection of fluorescence is performed with an excitation wavelength of 292 nm and emission wavelength of 325 nm. Both methods require a liquid-liquid extraction as sample preparation. The results of both HPLC methods have been tested by method comparison for n = 25 serum samples versus an isotope dilution-gas chromatography-mass spectrometry (ID-GC-MS) method using alpha-tocopherol-d6 as internal standard. The imprecision within-run was lower than 2.5% for the UV method and lower than 1% for the fluorescence method for both standards and serum pools. The between-run imprecision, obtained for serum pools, was below 5% for the UV method and not higher than 1.5% for the fluorescence method and not higher 1.8% for the ID-GC-MS. Recovery experiments performed by spiking pool sera with alpha-tocopherol showed recoveries between 98.5% and 100.6% for all methods studied. The result of the method comparison was a coefficient of correlation of r = 0.998 for the HPLC method with fluorescence detection to the ID-GC-MS reference method and a coefficient of correlation of r = 0.981 for the HPLC method with UV detection to the ID-GC-MS reference method. Both methods presented are useful for the analysis of alpha-tocopherol in patient samples. If detection of fluorescence is used, imprecision and inaccuracy of the HPLC method are comparable to the ID-GC-MS chosen as reference method. PMID:9189742

  19. Recent development in chromatographic techniques

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chromatographic techniques play a significant role in the determination of analytes in complex matrices, separating individual sample components prior to their detection. In the analysis of contaminants and chemical residues in foods, gas chromatography (GC) and liquid chromatography (LC) are two m...

  20. An eight-month sample of marine stratocumulus cloud fraction, albedo, and integrated liquid water

    NASA Technical Reports Server (NTRS)

    Fairall, C. W.; Hare, J. E.; Snider, J. B.

    1990-01-01

    Surface-meteorology and shortwave/longwave irradiance measurements taken on the northwest tip of San Nicolas Island off the coast of Southern California from March through October 1987 are analyzed. Experimental details are summarized, and shortwave cloud-radiation parameterization is outlined with emphasis on a shortwave algorithm. Frequency distributions indicate the stratocumulus clouds at the island have a cloud base on the order of 400 m, an integrated liquid water content of 75 g/sq m, and an albedo of 0.55 with substantial diurnal variations. The longwave parameterization for cloud fraction is also considered, and it is noted that using these models for downward longwave and shortwave irradiances, cloud fraction, integrated liquid water content, and albedo are deduced from the data.

  1. Chromatographic behavior of small organic compounds in low-temperature high-performance liquid chromatography using liquid carbon dioxide as the mobile phase.

    PubMed

    Motono, Tomohiro; Nagai, Takashi; Kitagawa, Shinya; Ohtani, Hajime

    2015-07-01

    Low-temperature high-performance liquid chromatography, in which a loop injector, column, and detection cell were refrigerated at -35ºC, using liquid carbon dioxide as the mobile phase was developed. Small organic compounds (polyaromatic hydrocarbons, alkylbenzenes, and quinones) were separated by low-temperature high-performance liquid chromatography at temperatures from -35 to -5ºC. The combination of liquid carbon dioxide mobile phase with an octadecyl-silica (C18 ) column provided reversed phase mode separation, and a bare silica-gel column resulted in normal phase mode separation. In both the cases, nonlinear behavior at approximately -15ºC was found in the relationship between the temperature and the retention factors of the analytes (van't Hoff plots). In contrast to general trends in high-performance liquid chromatography, the decrease in temperature enhanced the separation efficiency of both the columns. PMID:25917311

  2. CN-GELFrEE - Clear Native Gel-eluted Liquid Fraction Entrapment Electrophoresis.

    PubMed

    Melani, Rafael D; Seckler, Henrique S; Skinner, Owen S; Do Vale, Luis H F; Catherman, Adam D; Havugimana, Pierre C; Valle de Sousa, Marcelo; Domont, Gilberto B; Kelleher, Neil L; Compton, Philip D

    2016-01-01

    Protein complexes perform an array of crucial cellular functions. Elucidating their non-covalent interactions and dynamics is paramount for understanding the role of complexes in biological systems. While the direct characterization of biomolecular assemblies has become increasingly important in recent years, native fractionation techniques that are compatible with downstream analysis techniques, including mass spectrometry, are necessary to further expand these studies. Nevertheless, the field lacks a high-throughput, wide-range, high-recovery separation method for native protein assemblies. Here, we present clear native gel-eluted liquid fraction entrapment electrophoresis (CN-GELFrEE), which is a novel separation modality for non-covalent protein assemblies. CN-GELFrEE separation performance was demonstrated by fractionating complexes extracted from mouse heart. Fractions were collected over 2 hr and displayed discrete bands ranging from ~30 to 500 kDa. A consistent pattern of increasing molecular weight bandwidths was observed, each ranging ~100 kDa. Further, subsequent reanalysis of native fractions via SDS-PAGE showed molecular-weight shifts consistent with the denaturation of protein complexes. Therefore, CN-GELFrEE was proved to offer the ability to perform high-resolution and high-recovery native separations on protein complexes from a large molecular weight range, providing fractions that are compatible with downstream protein analyses. PMID:26967310

  3. Gas-liquid Phase Distribution and Void Fraction Measurements Using the MRI

    NASA Technical Reports Server (NTRS)

    Daidzic, N. E.; Schmidt, E.; Hasan, M. M.; Altobelli, S.

    2004-01-01

    We used a permanent-magnet MRI system to estimate the integral and spatially- and/or temporally-resolved void-fraction distributions and flow patterns in gas-liquid two-phase flows. Air was introduced at the bottom of the stagnant liquid column using an accurate and programmable syringe pump. Air flow rates were varied between 1 and 200 ml/min. The cylindrical non-conducting test tube in which two-phase flow was measured was placed in a 2.67 kGauss MRI with MRT spectrometer/imager. Roughly linear relationship has been obtained for the integral void-fraction, obtained by volume-averaging of the spatially-resolved signals, and the air flow rate in upward direction. The time-averaged spatially-resolved void fraction has also been obtained for the quasi-steady flow of air in a stagnant liquid column. No great accuracy is claimed as this was an exploratory proof-of-concept type of experiment. Preliminary results show that MRI a non-invasive and non-intrusive experimental technique can indeed provide a wealth of different qualitative and quantitative data and is especially well suited for averaged transport processes in adiabatic and diabatic multi-phase and/or multi-component flows.

  4. [Effects of carrier liquid and flow rate on the separation in gravitational field-flow fractionation].

    PubMed

    Guo, Shuang; Zhu, Chenqi; Gao-Yang, Yaya; Qiu, Bailing; Wu, Di; Liang, Qihui; He, Jiayuan; Han, Nanyin

    2016-02-01

    Gravitational field-flow fractionation is the simplest field-flow fractionation technique in terms of principle and operation. The earth' s gravity is its external field. Different sized particles are injected into a thin channel and carried by carrier fluid. The different velocities of the carrier liquid in different places results in a size-based separation. A gravitational field-flow fractionation (GrFFF) instrument was designed and constructed. Two kinds of polystyrene (PS) particles with different sizes (20 µm and 6 µm) were chosen as model particles. In this work, the separation of the sample was achieved by changing the concentration of NaN3, the percentage of mixed surfactant in the carrier liquid and the flow rate of carrier liquid. Six levels were set for each factor. The effects of these three factors on the retention ratio (R) and plate height (H) of the PS particles were investigated. It was found that R increased and H decreased with increasing particle size. On the other hand, the R and H increased with increasing flow rate. The R and H also increased with increasing NaN3 concentration. The reason was that the electrostatic repulsive force between the particles and the glass channel wall increased. The force allowed the samples approach closer to the channel wall. The results showed that the resolution and retention time can be improved by adjusting the experimental conditions. These results can provide important values to the further applications of GrFFF technique. PMID:27382718

  5. Online Peptide Fractionation Using a Multiphasic Microfluidic Liquid Chromatography Chip Improves Reproducibility and Detection Limits for Quantitation in Discovery and Targeted Proteomics*

    PubMed Central

    Krisp, Christoph; Yang, Hao; van Soest, Remco; Molloy, Mark P

    2015-01-01

    Comprehensive proteomic profiling of biological specimens usually requires multidimensional chromatographic peptide fractionation prior to mass spectrometry. However, this approach can suffer from poor reproducibility because of the lack of standardization and automation of the entire workflow, thus compromising performance of quantitative proteomic investigations. To address these variables we developed an online peptide fractionation system comprising a multiphasic liquid chromatography (LC) chip that integrates reversed phase and strong cation exchange chromatography upstream of the mass spectrometer (MS). We showed superiority of this system for standardizing discovery and targeted proteomic workflows using cancer cell lysates and nondepleted human plasma. Five-step multiphase chip LC MS/MS acquisition showed clear advantages over analyses of unfractionated samples by identifying more peptides, consuming less sample and often improving the lower limits of quantitation, all in highly reproducible, automated, online configuration. We further showed that multiphase chip LC fractionation provided a facile means to detect many N- and C-terminal peptides (including acetylated N terminus) that are challenging to identify in complex tryptic peptide matrices because of less favorable ionization characteristics. Given as much as 95% of peptides were detected in only a single salt fraction from cell lysates we exploited this high reproducibility and coupled it with multiple reaction monitoring on a high-resolution MS instrument (MRM-HR). This approach increased target analyte peak area and improved lower limits of quantitation without negatively influencing variance or bias. Further, we showed a strategy to use multiphase LC chip fractionation LC-MS/MS for ion library generation to integrate with SWATHTM data-independent acquisition quantitative workflows. All MS data are available via ProteomeXchange with identifier PXD001464. PMID:25850434

  6. Online Peptide fractionation using a multiphasic microfluidic liquid chromatography chip improves reproducibility and detection limits for quantitation in discovery and targeted proteomics.

    PubMed

    Krisp, Christoph; Yang, Hao; van Soest, Remco; Molloy, Mark P

    2015-06-01

    Comprehensive proteomic profiling of biological specimens usually requires multidimensional chromatographic peptide fractionation prior to mass spectrometry. However, this approach can suffer from poor reproducibility because of the lack of standardization and automation of the entire workflow, thus compromising performance of quantitative proteomic investigations. To address these variables we developed an online peptide fractionation system comprising a multiphasic liquid chromatography (LC) chip that integrates reversed phase and strong cation exchange chromatography upstream of the mass spectrometer (MS). We showed superiority of this system for standardizing discovery and targeted proteomic workflows using cancer cell lysates and nondepleted human plasma. Five-step multiphase chip LC MS/MS acquisition showed clear advantages over analyses of unfractionated samples by identifying more peptides, consuming less sample and often improving the lower limits of quantitation, all in highly reproducible, automated, online configuration. We further showed that multiphase chip LC fractionation provided a facile means to detect many N- and C-terminal peptides (including acetylated N terminus) that are challenging to identify in complex tryptic peptide matrices because of less favorable ionization characteristics. Given as much as 95% of peptides were detected in only a single salt fraction from cell lysates we exploited this high reproducibility and coupled it with multiple reaction monitoring on a high-resolution MS instrument (MRM-HR). This approach increased target analyte peak area and improved lower limits of quantitation without negatively influencing variance or bias. Further, we showed a strategy to use multiphase LC chip fractionation LC-MS/MS for ion library generation to integrate with SWATH(TM) data-independent acquisition quantitative workflows. All MS data are available via ProteomeXchange with identifier PXD001464. PMID:25850434

  7. A Versatile, Automatic Chromatographic Column Packing Device

    ERIC Educational Resources Information Center

    Barry, Eugene F.; And Others

    1977-01-01

    Describes an inexpensive apparatus for packing liquid and gas chromatographic columns of high efficiency. Consists of stainless steel support struts, an Automat Getriebmotor, and an associated three-pulley system capable of 10, 30, and 300 rpm. (MLH)

  8. Gas chromatograph injection port protective device

    NASA Technical Reports Server (NTRS)

    Robertson, M. D.; Welz, E. A.

    1969-01-01

    To prevent samples containing foreign matter from poisoning the gas chromatographic columns, a pre-filter insertion is placed in the injection port. The packing becomes a variable reactant, for example, acids are removed by using an alkaline liquid.

  9. Development and validation of reversed-phase column high-performance liquid chromatographic and first-derivative UV spectrophotometric methods for estimation of voriconazole in oral suspension powder.

    PubMed

    Prajapati, Arun M; Patel, Satish A; Patel, Natvarlal J; Patel, Dipti B; Patel, Sejal K

    2008-01-01

    This research paper describes validated reversed-phase high-performance column liquid chromatographic (RP-HPLC) and first-derivative UV spectrophotometric methods for the estimation of voriconazole (VOR) in oral suspension powder. The RP-HPLC separation was achieved on Phenomenex C18 column (250 x 4.6 mm id, 5 microm particle size) using water-acetonitrile (40 + 60, v/v; pH adjusted to 4.5 +/- 0.02 with acetic acid) as the mobile phase at a flow rate of 1.4 mL/min and ambient temperature. Quantification was achieved with photodiode array detection at 255 nm over the concentration range of 0.1-1 microg/mL with mean recovery of 99.49 +/- 0.83% for VOR by the RP-HPLC method. Quantification was achieved with UV detection at 266 nm over the concentration range of 8-20 microg/mL with mean recovery of 99.74 +/- 0.664% for VOR by the first-derivative UV spectrophotometric method. These methods are simple, precise, and sensitive, and they are applicable for the determination of VOR in oral suspension powder. PMID:18980120

  10. A novel liquid chromatographic method with fluorescence detection for quantitation of tadalafil and dapoxetine hydrochloride in pharmaceutical dosage form and human plasma.

    PubMed

    Maha, Hegazy; Amira, Kessiba; Mohamed, Abdelkawy; Ahmed Emad, El Gindy

    2015-07-01

    Tadalafil (TAD) and dapoxetine HCl (DAP) are recently co-formulated and both show native fluorescence. Therefore, a novel, accurate, specific and sensitive reversed-phase high performance liquid chromatographic method with fluorescence detection was developed and validated for their separation and quantitation in dosage form and human plasma using avanafil as an internal standard (IS). Separation was achieved using isocratic elution within 7.0 min on C18 column and acetonitrile-0.15% triethylamine (40:60, v/v; pH 4) as a mobile phase. The flow rate was 1.0 mL/min and the detection was time-programmed at 330, 410 and 370 nm for TAD, DAP and IS, respectively, after excitation at 236 nm. The linear ranges from 0.01 to 30.00 μg/mL for each drug with the limits of detection of 4.20 and 7.20 ng/mL for TAD and DAP, respectively. The method was validated in accordance to the International Conference on Harmonization (ICH) guidelines and was successfully applied to spiked human plasma with mean recoveries of 98.17% and 98.83% for TAD and DAP respectively. PMID:26672207

  11. High-performance liquid chromatographic resolution of reverse isomers of 1,2-diacyl-rac-glycerols as 3,5-dinitrophenylurethanes.

    PubMed

    Itabashi, Y; Myher, J J; Kuksis, A

    2000-10-01

    The resolution of reverse isomers remains a major unsolved problem in glycerolipid chromatography. We have investigated the separation of the reverse isomers of 1,2-diacyl-rac-glycerols under a variety of high-performance liquid chromatography (HPLC) conditions. The reverse isomers of diacylglycerols having various pairs of acyl groups including short and highly unsaturated chains, which were prepared by partial Grignard degradation of the corresponding triacylglycerols, were chromatographed as 3,5-dinitrophenylurethanes. Excellent resolution was achieved for the reverse isomers of very different pairs of acyl groups, such as acetate-palmitate and docosahexaenoate-palmitate, by chiral-phase HPLC on columns containing (R)- and (S)-1-(1-naphthyl)ethylamine polymeric phases, reversed-phase HPLC on a highly efficient C18 column (4 microm particle size) and silver ion HPLC on a silver loaded cation-exchange column. The chiral-phase HPLC also permitted complete enantiomer resolution for all the reverse isomers examined. No satisfactory resolution by any of the HPLC methods, however, was obtained for the reverse isomers possessing minor differences in chain lengths and degree of unsaturation, such as laurate-palmitate and oleate-linoleate. The limitations of resolution and characteristics of elution are described. PMID:11073297

  12. Limits of detections for the determination of mono- and dicarboxylic acids using gas and liquid chromatographic methods coupled with mass spectrometry

    PubMed Central

    Št’ávová, Jana; Beránek, Josef; Nelson, Eric P.; Diep, Bonnie A.; Kubátová, Alena

    2011-01-01

    The chromatographic separation and instrumental limits of detection (LODs) were obtained for a broad range of C1-C18 monocarboxylic (MCAs) and C2-C14 dicarboxylic acids (DCAs) employing either chemical derivatization followed by gas chromatography-mass spectrometry and flame ionization detection (GC-MS/FID) or direct analysis with liquid chromatography high resolution MS and tandem MS (LC-MS). Suitability, efficiency and stability of reaction products for several derivatization agents used for esterification (BF3/butanol), and trimethysilylation, including trimethylsilyl-N-N-dimethylcarbamate (TMSDMC) and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) were evaluated. The lowest limits of detection for the majority of compounds below 10 pg (with the exception of acetic acid) were obtained for derivatization with BF3/butanol followed by GC-MS in the total ion current (TIC) mode. Further improvements were achieved when applying either selected ion monitoring (SIM), which decreased the LODs to 1–4 pg or a combination of SIM and TIC (SITI) (2–5 pg). GC-FID provided LODs comparable to those obtained by GC-MS TIC. Both trimethylsilylation (followed by GC-MS) and direct LC-MS/MS analysis yielded LODs of 5– 40 pg for most of the acids. For volatile acids the LODs were higher, e.g., 25 and 590 ng for TMSDMC and BSTFA derivatized formic acid, respectively whereas the LC-MS methods did not allow for the analysis of formic acid at all. PMID:21185238

  13. Determination and pharmacokinetics of a new diorganotin(IV) complex dibutyldi(4-chlorobenzohydroxamato)tin(IV) in rat plasma by a high performance liquid chromatographic method.

    PubMed

    Li, Yunlan; Liu, Jinjie; Li, Yong; Li, Qingshan

    2009-05-01

    Dibutyldi(4-chlorobenzohydroxamato)tin(IV) is a new diorganotin(IV) arylhydroxamate complex with 4-chloro-benzohydroxamic acid as ligand which shows high in vivo and in vitro antitumor activity. A high performance liquid chromatographic (HPLC) method using a Diamonsil ODS column was first validated in the pharmacokinetic studies in rat plasma. The plasma was deproteinized with methanol that contained acetanilide as the internal standard. The mobile phase was a mixture of methanol and 0.5% trifluoroacetic acid (TFA) in water (30:70) (pH 3.0). The detection wavelength was set at 238 nm. A linear curve over the concentration range 0.1-25 microg/ml (r = 0.9992) was obtained. The method was used to determine the concentration-time profiles for dibutyldi(4-chlorobenzohydroxamato)tin(IV) in the plasma after a single intravenous dose of 2, 5, and 12 mg/kg to rats. The pharmacokinetics parameter calculations and modeling were carried out using the 3p97 pharmacokinetics software. A nonlinear pharmacokinetics was found in rats at doses from 2 to 12 mg/kg. The results showed that the concentration-time curves of dibutyldi(4-chlorobenzohydroxamato)-tin(IV) in rat plasma could be fitted to two-compartment model. PMID:19430156

  14. Validation of a Stability-Indicating Hydrophilic Interaction Liquid Chromatographic Method for the Quantitative Determination of Vitamin K3 (Menadione Sodium Bisulfite) in Injectable Solution Formulation

    PubMed Central

    Ghanem, Mashhour M.; Abu-Lafi, Saleh A.; Hallak, Hussein O.

    2013-01-01

    A simple, specific, accurate, and stability-indicating method was developed and validated for the quantitative determination of menadione sodium bisulfite in the injectable solution formulation. The method is based on zwitterionic hydrophilic interaction liquid chromatography (ZIC-HILIC) coupled with a photodiode array detector. The desired separation was achieved on the ZIC-HILIC column (250 mm × 4.6 mm, 5 μm) at 25°C temperature. The optimized mobile phase consisted of an isocratic solvent mixture of 200mM ammonium acetate (NH4AC) solution and acetonitrile (ACN) (20:80; v/v) pH-adjusted to 5.7 by glacial acetic acid. The mobile phase was fixed at 0.5 ml/min and the analytes were monitored at 261 nm using a photodiode array detector. The effects of the chromatographic conditions on the peak retention, peak USP tailing factor, and column efficiency were systematically optimized. Forced degradation experiments were carried out by exposing menadione sodium bisulfite standard and the injectable solution formulation to thermal, photolytic, oxidative, and acid-base hydrolytic stress conditions. The degradation products were well-resolved from the main peak and the excipients, thus proving that the method is a reliable, stability-indicating tool. The method was validated as per ICH and USP guidelines (USP34/NF29) and found to be adequate for the routine quantitative estimation of menadione sodium bisulfite in commercially available menadione sodium bisulfite injectable solution dosage forms. PMID:24106670

  15. Validated and optimized high-performance liquid chromatographic determination of tizoxanide, the main active metabolite of nitazoxanide in human urine, plasma and breast milk.

    PubMed

    Hadad, Ghada M; Abdel Salam, Randa A; Emara, Samy

    2012-07-01

    A high-performance liquid chromatographic method was optimized and validated for the determination of desacetyl nitazoxanide (tizoxanide), the main active metabolite of nitazoxanide in human plasma, urine and breast milk. The proposed method used a CN column with mobile phase consisting of acetonitrile-12mM ammonium acetate-diethylamine in the ratio of 30:70:0.1 (v/v/v) and buffered at pH 4.0 with acetic acid, with a flow rate of 1.5 mL/min. Quantitation was achieved with UV detection at 260 nm using nifuroxazide as internal standard. A simplified direct injection of urine samples without extraction in addition to the urinary excretion pattern were calculated using the proposed method. Also, the effectiveness of protein precipitation and a clean-up procedure were investigated for biological plasma and human breast milk samples. The validation study of the proposed method was successfully carried out in an assay range between 0.2 and 20 µg/mL. PMID:22525879

  16. High-performance liquid chromatographic method for profiling 2-oxo acids in urine and its application in evaluating vitamin status in rats.

    PubMed

    Shibata, Katsumi; Nakata, Chifumi; Fukuwatari, Tsutomu

    2016-01-01

    B-group vitamins are involved in the catabolism of 2-oxo acids. To identify the functional biomarkers of B-group vitamins, we developed a high-performance liquid chromatographic method for profiling 2-oxo acids in urine and applied this method to urine samples from rats deficient in vitamins B1 and B6 and pantothenic acid. 2-Oxo acids were reacted with 1,2-diamino-4,5-methylenebenzene to produce fluorescent derivatives, which were then separated using a TSKgel ODS-80Ts column with 30 mmol/L of KH2PO4 (pH 3.0):acetonitrile (7:3) at a flow rate of 1.0 mL/min. Vitamin B1 deficiency increased urinary levels of all 2-oxo acids, while vitamin B6 deficiency only increased levels of sum of 2-oxaloacetic acid and pyruvic acid, and pantothenic acid deficiency only increased levels of 2-oxoisovaleric acid. Profiles of 2-oxo acids in urine samples might be a non-invasive way of clarifying the functional biomarker of B-group vitamins. PMID:26745680

  17. Stability-Indicating Liquid Chromatographic Method for the Quantification of the New Antipsychotic Agent Asenapine in Bulk and in Pharmaceutical Formulation

    PubMed Central

    Chhalotiya, Usmangani K.; Bhatt, Kashyap K.; Shah, Dimal A.; Patel, Jigar R.

    2012-01-01

    A simple, specific and stability-indicating reversed phase high performance liquid chromatographic method was developed for the quantitative determination of asenapine in tablet dosage form. A SunFire C18, 5 μm column having 250×4.6 mm i.d. in isocratic mode, with mobile phase containing 0.02 M potassium dihydrogen phosphate: acetonitrile (95:05, v/v, pH 3.5 adjusted with 1% o-phosphoric acid) was used. The flow rate was 1.0 mL min−1 and effluents were monitored at 232 nm. The retention time of asenapine was 5.51 min. The linearity for asenapine was in the range of 0.1–20 μg/ml. The recoveries obtained for asenapine were 98.31–101.51%. Asenapine stock solutions were subjected to acid and alkali hydrolysis, chemical oxidation, sunlight and dry heat degradation. The degraded product peaks were well resolved from the pure drug peak with significant difference in their retention time values. Stressed samples were assayed using developed LC method. The proposed method was validated with respect to linearity, accuracy, precision and robustness. The method was successfully applied to the estimation of asenapine in tablet dosage form. PMID:22896826

  18. Cell bioassay for paralytic shellfish poisoning (PSP): comparison with postcolumn derivatization liquid chromatographic analysis and application to the monitoring of PSP in shellfish.

    PubMed

    Hayashi, Rumiko; Saito, Hiroshi; Okumura, Masanao; Kondo, Fumio

    2006-01-25

    We performed a neuroblastoma cell (Neuro2a) culture assay modified slightly from a method reported previously to provide a simple and sensitive evaluation of paralytic shellfish poisoning (PSP) toxicity in shellfish. The cell bioassay was just as sensitive for C-toxins as for gonyautoxins. The sensitivity of our cell bioassay was 4 times that of the current standard mouse bioassay. Using the cell bioassay, we evaluated PSP toxicity in 361 shellfish samples collected from Mikawa Bay and Ise Bay, Aichi Prefecture, Japan, from April 1999-March 2002. The results were compared with those obtained in a postcolumn derivatization liquid chromatographic analysis. PSP toxins were detected in 236/361 samples by both assays, and there was a fairly good correlation (r = 0.9001, n = 236, p < 0.001) between the results from the two assays. We applied this cell bioassay when short-necked clams in the bay turned poisonous in 2001. The chronological changes in PSP toxicity in the short-necked clams were analyzed and compared with those of the cell density of poisonous plankton (Alexandrium tamarense) occurring in the bay. The PSP toxicity in shellfish peaked 2 weeks after the cell density reached a maximum. We recommend using the cell bioassay for routine monitoring of PSP toxicity in shellfish living in natural marine environments. PMID:16417278

  19. Chromatographic comparison of atenolol separation in reaction media on cellulose tris-(3,5-dimethylphenylcarbamate) chiral stationary phase using ultra fast liquid chromatography.

    PubMed

    Agustian, Joni; Kamaruddin, Azlina Harun; Aboul-Enein, Hassan Y

    2012-05-01

    Because chiral liquid chromatography (LC) could become a powerful tool to estimate racemic atenolol quantity, excellent enantiomeric separation should be produced during data acquisition for satisfactory observation of atenolol concentrations throughout the racemic resolution processes. Selection of chiral LC column and analytical protocol that fulfill demands of the ultra fast LC analysis is essential. This article describes the characteristics of atenolol chromatographic separation that resulted from different resolution media and analytical protocols with the use of a Chiralcel® OD column. The chromatograms showed quite different characteristics of the separation process. The single enantiomer and racemic atenolol could be recognized by the Chiralcel® OD column in less than 20 min. Symmetrical peaks were obtained; however, several protocols produced peaks with wide bases and slanted baselines. Observations showed that efficient enantioresolution of racemic atenolol was obtained at slow mobile phase flow rate, decreased concentration of amine-type modifier but increased alcohol content in mobile phase and highest ultraviolet detection wavelength were required. The optimal ultra fast LC protocol enables to reduce and eliminate the peaks of either the atenolol solvent or the buffers and provided the highest peak intensities of both atenolol enantiomers. PMID:22517322

  20. Development and validation of a liquid chromatographic method for purity control of clopidogrel-acetylsalicylic acid in combined oral dosage forms.

    PubMed

    Kahsay, Getu; Van Schepdael, Ann; Adams, Erwin

    2012-03-01

    A reversed phase liquid chromatographic method with UV detection for the simultaneous determination of clopidogrel and acetylsalicylic acid and their related substances in combined oral formulations was developed and validated. Good separation was achieved on a Luna C18 column (150 mm × 4.6 mm, 3 μm) using gradient elution at a flow rate of 1 mL/min and a column temperature of 35 °C. UV detection was performed at 220 nm. The validation was performed according to the ICH guidelines. The method proved to be specific, sensitive (LOQ=0.975 μg/mL and 0.0384 μg/mL for clopidogrel and acetylsalicylic acid, respectively), linear in the concentration range from LOQ to 325 μg/mL for clopidogrel and from LOQ to 650 μg/mL for acetylsalicylic acid, precise (RSD values for intermediate precision <1%) and accurate with mean recovery values of 100.7% and 100.2% for clopidogrel and acetylsalicylic acid, respectively. Moreover, the solution stability and method robustness were examined. The method gives satisfactory separation of impurities of clopidogrel and acetylsalicylic acid and so it is suitable for quantification of the related substances as well as for the assay of the actives. PMID:22226416

  1. Validated stability-indicating liquid chromatographic method for the determination of ribavirin in the presence of its degradation products: application to degradation kinetics.

    PubMed

    Belal, Fathalla; Sharaf El-Din, Mohie K; Eid, Manal I; El-Gamal, Rania M

    2015-04-01

    Ribavirin was found to be liable to acidic, alkaline, oxidative and photolytic degradation. Hence, a simple, sensitive and stability-indicating reversed-phase liquid chromatographic method was developed and validated for the determination of ribavirin in the presence of its degradation products. The analysis was carried out on an ODS C18 (250 × 4.6 mm i.d.) stainless steel column using a mobile phase consisting of 0.02 M potassium dihydrogen phosphate. The analysis was performed at ambient temperature with a flow rate of 1 mL/min and UV detection at 207 nm. Pyridoxine hydrochloride was used as an internal standard. The method showed good linearity over the concentration range of 2.0-40 µg/mL with limit of detection of 0.34 µg/mL and limit of quantification of 1.03 µg/mL. The suggested method was successfully applied for the analysis of ribavirin in its commercial capsules. Statistical evaluation and comparison of the data obtained by the proposed and comparison method revealed good accuracy and precision of the proposed method. The drug was exposed to forced alkaline, acidic, oxidative and photolytic degradation according to the ICH guidelines. Moreover, the method was utilized to investigate the kinetics of alkaline and acidic degradation of the drug. The apparent first-order rate constants, half-life times and activation energies of the degradation process were calculated. PMID:25092904

  2. New validated liquid chromatographic and chemometrics-assisted UV spectroscopic methods for the determination of two multicomponent cough mixtures in syrup.

    PubMed

    Hadad, Ghada M; El-Gindy, Alaa; Mahmoud, Waleed M M

    2008-01-01

    Multivariate spectrophotometric calibration and liquid chromatographic (LC) methods were applied to the determination of 2 multicomponent mixtures containing diprophylline, guaiphenesin, methylparaben, and propylparaben (Mixture 1), or clobutinol, orciprenaline, saccharin sodium, and sodium benzoate (Mixture 2). For the multivariate spectrophotometric calibration methods, principal component regression (PCR) and partial least-squares regression (PLS-1), a calibration set of the mixtures consisting of the components of each mixture was prepared in 0.1 M HCl. Analytical figures of merit such as sensitivity, selectivity, limit of quantitation, and limit of detection were determined for both PLS-1 and PCR. The LC separation was achieved on a reversed-phase C18 analytical column by using isocratic elution with 20 mM potassium dihydrogen phosphate, pH 3.3-acetonitrile (55 + 45, v/v) as the mobile phase and UV detection at 260 and 220 nm for Mixture 1 and Mixture 2, respectively. The proposed methods were validated and successfully applied to the analysis of pharmaceutical formulations and laboratory-prepared mixtures containing the 2 multicomponent combinations. PMID:18376584

  3. Spectrophotometric and reversed-phase high-performance liquid chromatographic methods for simultaneous determination of escitalopram oxalate and clonazepam in combined tablet dosage form.

    PubMed

    Gandhi, Santosh Vilashchand; Dhavale, Nilesh Dnyandev; Jadhav, Vijay Yeshawantrao; Sabnis, Shweta Sadanand

    2008-01-01

    Simple, accurate, precise, and sensitive ultraviolet spectrophotometric and reversed-phase high-performance liquid chromatographic (RP-HPLC) methods for simultaneous estimation of escitalopram oxalate (ESC) and clonazepam (CLO) in combined tablet dosage form have been developed and validated. The spectroscopic method employs an absorbance correction method using 238.6 and 308 nm as 2 wavelengths for estimation with methanol and water as solvents. Beer's law is obeyed in the concentration range of 10.0-50.0 and 0.5-3.0 micro/mL for ESC and CLO, respectively. The RP-HPLC method uses a Jasco HPLC system with HiQ SiL C18 column (250 x 4.6 mm id) acetonitrile-0.005 M tetrabutylammonium hydrogen sulfate (55 + 45, v/v) as the mobile phase, and satranidazole as an internal standard. The detection was carried out using an ultraviolet detector set at 287 nm. For the HPLC method, Beer's law is obeyed in the concentration range of 10.0-60.0 and 0.5-3.0 microg/mL for ESC and CLO, respectively. Both methods have been successfully applied for the analysis of the drugs in a pharmaceutical formulation. Results of analysis were validated statistically and by recovery studies. PMID:18376583

  4. Stereospecific determination of an HIV aspartyl protease inhibitor, PNU-103017, in rat, dog and human plasma using a Pirkle-concept high-performance liquid chromatographic column.

    PubMed

    Williams, M G; Zhong, W Z

    1997-06-20

    A sensitive stereospecific high-performance liquid chromatographic assay for the quantitation of the enantiomers of 4-cyano-N-(3-(cyclopropyl-(5,6,7,8,9,10-hexahydro-4-hydroxy-2-oxo-2H- cycloocta(b)pyran-3-yl)methyl)phenyl)benzenesulfonamide (PNU-103017) (I), an HIV protease inhibitor, in plasma of rat, dog and human was developed. The procedure involved an acetonitrile-aided protein precipitation followed by solid-phase extraction (SPE) of I from plasma into ethanol. Stereospecific separation was accomplished on a Pirkle-concept chiral column (Regis S,S-Whelk-01, 250x4.6 mm I.D.) with a mobile phase of absolute ethanol-0.1% acetic acid in hexane (30:70, v/v). The eluate was monitored by UV absorbance (295 nm). Linear calibration curves were obtained in the range of 0.2 to 500 microM, with a lower limit of quantitation of 0.1-0.2 microM for both enantiomers in either rat, dog or human plasma. Intra- and inter-assay precision and assay accuracy were demonstrated to be acceptable for the stereoselective pharmacokinetic analysis of I in plasma. PMID:9234860

  5. High-performance liquid chromatographic enantioseparation of cyclic β-aminohydroxamic acids on zwitterionic chiral stationary phases based on Cinchona alkaloids.

    PubMed

    Lajkó, Gyula; Orosz, Tímea; Grecsó, Nóra; Fekete, Beáta; Palkó, Márta; Fülöp, Ferenc; Lindner, Wolfgang; Péter, Antal; Ilisz, István

    2016-05-19

    Cyclic β-aminohydroxamic acid enantiomer pairs were stereoselectively separated by high-performance liquid chromatography on the recently developed Cinchona alkaloid-based zwitterionic chiral stationary phases Chiralpak ZWIX(+)™, ZWIX(-)™, ZWIX(+A) and ZWIX(-A). The results of variation of the applied chromatographic conditions, such as the bulk solvent composition, the concentrations and ratio of the acid and base additives, the presence of water as mobile phase additive and the counter-ion concentration furnished a better understanding of the retention mechanism. A thermodynamic study in the temperature range 5-50 °C revealed enthalpy-controlled enantiodiscrimination in all cases. The structure-selectivity relationships clearly indicated the importance of the strereochemistry of the functional groups. From an enantiorecognition aspect, the diexo position of the functional groups always proved more favorable than the diendo position. The elution sequence was determined in all cases and was found to reversed when ZWIX(+)™ was changed to ZWIX(-)™ or ZWIX(+A) to ZWIX(-A). PMID:27126793

  6. A rapid high-performance liquid chromatographic method for the simultaneous quantitation of aspirin, salicylic acid, and caffeine in effervescent tablets.

    PubMed

    Sawyer, MaryJean; Kumar, Vimal

    2003-09-01

    A rapid reversed-phase high-performance liquid chromatographic procedure is developed and validated for the simultaneous quantitation of aspirin, salicylic acid, and caffeine extracted from an effervescent tablet. The method uses a Hypersil C18 column (5 micro m, 15 cm x 4.6 mm) for an isocratic elution in a water-methanol-acetic acid mobile phase at a wavelength of 275 nm. The tablets' buffering effects and acid neutralizing capacity require an extraction solvent of methanol-formic acid. The range of linearity for aspirin is 0.5-1.25 mg/mL, caffeine 0.065-0.195 mg/mL, and salicylic acid 0.4-6.0% of aspirin. The overall recovery is 100.2%, 100.7%, and 99.2% for aspirin, caffeine, and salicylic acid, respectively. Under the conditions of the method, aspirin, caffeine, and salicylic acid are adequately resolved with proper peak symmetry in less than 7 min. PMID:14558930

  7. Validated high performance liquid chromatographic method for simultaneous determination of rosiglitazone, cilostazol, and 3,4-dehydro-cilostazol in rat plasma and its application to pharmacokinetics.

    PubMed

    Varanasi, V S Kanthi Kiran; Veeraraghavan, Sridhar; Potharaju, Suresh; Thappali, R S Satheeshmanikandan; Raghavan, Rashmi; Vakkalanka, V S Swaroop Kumar

    2008-01-01

    A high performance liquid chromatographic (HPLC) method for simultaneous determination of rosiglitazone, CAS 122320-73-4, RSG), cilostazol (CAS 73963-72-1, CLZ) and its active metabolite 3, 4-dehydro-cilostazol (DCLZ), using pioglitazone (PIO) as internal standard (IS), in rat plasma is described. The plasma was extracted with methyl t-butyl ether, the dry extract was reconstituted in mobile phase and the aliquot was injected. The eluent drugs were detected by UV at dual wavelength of 226 nm (RSG and DCLZ) and 257 nm (CLZ). The mobile phase consisting of acetonitrile:potassium di-hydrogen phosphate buffer (35:65 v/v) was used at the flow rate of 1.2 ml/min on a reverse phase C18 column. The absolute recovery was above 90% of all analytes over the concentration range of 25-2500 ng/ml for RSG and CLZ and 20-2000 ng/ ml for DCLZ. The relative standard deviation (RSD) of the inter-day and intra-day precision ranged from 2.8 to 8.4% and 0.9 to 5.9%, respectively. The method is simple, rapid, accurate and sensitive and was applied to pharmacokinetic studies. PMID:18677971

  8. Quality by Design approach in the development of hydrophilic interaction liquid chromatographic method for the analysis of iohexol and its impurities.

    PubMed

    Jovanović, Marko; Rakić, Tijana; Tumpa, Anja; Jančić Stojanović, Biljana

    2015-06-10

    This study presents the development of hydrophilic interaction liquid chromatographic method for the analysis of iohexol, its endo-isomer and three impurities following Quality by Design (QbD) approach. The main objective of the method was to identify the conditions where adequate separation quality in minimal analysis duration could be achieved within a robust region that guarantees the stability of method performance. The relationship between critical process parameters (acetonitrile content in the mobile phase, pH of the water phase and ammonium acetate concentration in the water phase) and critical quality attributes is created applying design of experiments methodology. The defined mathematical models and Monte Carlo simulation are used to evaluate the risk of uncertainty in models prediction and incertitude in adjusting the process parameters and to identify the design space. The borders of the design space are experimentally verified and confirmed that the quality of the method is preserved in this region. Moreover, Plackett-Burman design is applied for experimental robustness testing and method is fully validated to verify the adequacy of selected optimal conditions: the analytical column ZIC HILIC (100 mm × 4.6 mm, 5 μm particle size); mobile phase consisted of acetonitrile-water phase (72 mM ammonium acetate, pH adjusted to 6.5 with glacial acetic acid) (86.7:13.3) v/v; column temperature 25 °C, mobile phase flow rate 1 mL min(-1), wavelength of detection 254 nm. PMID:25796982

  9. Gas-liquid chromatographic and gas-liquid-mass spectometric determination of fenvalerate and permethrin residues in grasshoppers and duck tissue samples

    USGS Publications Warehouse

    Reichel, W.L.; Kolbe, E.J.; Stafford, C.J.

    1981-01-01

    A procedure is described for determining fenvalerate and permethrin residues in grasshoppers and duck tissues. Samples are Soxhlet-extracted with hexane and cleaned up by gel permeation chromatography with an in-line alumina column. Samples are analyzed by gas-liquid chromatography with electron capture detection, and confirmed by gas-liquid chromatography-mass spectrometry. The average recovery from fortified tissues was 97%.

  10. Validation of a Chiral Liquid Chromatographic Method for the Degradation Behavior of Flumequine Enantiomers in Mariculture Pond Water.

    PubMed

    Wang, Yan-Fei; Gao, Xiao-Feng; Jin, Huo-Xi; Wang, Yang-Guang; Wu, Wei-Jian; Ouyang, Xiao-Kun

    2016-09-01

    In this work, flumequine (FLU) enantiomers were separated using a Chiralpak OD-H column, with n-hexane-ethanol (20:80, v/v) as the mobile phase at a flow rate of 0.6 mL/min. Solid phase extraction (SPE) was used for cleanup and enrichment. The limit of detection, limit of quantitation, linearity, precision, and intra/interday variation of the chiral high-performance liquid chromatography (HPLC) method were determined. The developed method was then applied to investigate the degradation behavior of FLU enantiomers in mariculture pond water samples. The results showed that the degradation of FLU enantiomers under natural, sterile, or dark conditions was not enantioselective. Chirality 28:649-655, 2016. © 2016 Wiley Periodicals, Inc. PMID:27483447

  11. MSPD sample preparation approach for reversed-phase liquid chromatographic analysis of pesticide residues in stem of coconut palm.

    PubMed

    Ferreira, Jordana Alves; Santos, Luís Fabrício Santana; Souza, Nicaellen Roberta da Silva; Navickiene, Sandro; de Oliveira, Frederico Alberto; Talamini, Viviane

    2013-08-01

    A method was developed using matrix solid-phase dispersion, together with liquid chromatography with ultraviolet diode array detector for determination of carbofuran, difenoconazole, β-cyfluthrin, spirodiclofen and thiophanate-methyl in stem of coconut palm. The best results were obtained using 2.0 g of stem, 1.6 g of Florisil as sorbent and cyclohexane:acetone mixture (4:1). The method was validated using stem samples spiked with pesticides at four concentration levels (0.05-2.0 μg/g). Average recoveries ranged from 70 % to 114.3 %, with relative standard deviations between 1.2 % and 19.2 %. Detection and quantification limits were in the ranges 0.02-0.03 and 0.05-0.1 μg/g, respectively. PMID:23722654

  12. High-performance liquid chromatographic, capillary electrophoretic and capillary electrophoretic-electrospray ionisation mass spectrometric analysis of selected alkaloid groups.

    PubMed

    Stöckigt, Joachim; Sheludk, Yuri; Unger, Matthias; Gerasimenko, Irina; Warzecha, Heribert; Stöckigt, Detlef

    2002-08-16

    Systems for efficient separation of selected alkaloid groups by high performance liquid chromatography (HPLC), capillary electrophoresis (CE) and capillary electrophoresis coupled with electrospray ionisation mass spectrometry (CE-ESI-MS) are described. The optimized HPLC system was applied for the separation of 23 standard indole alkaloids as well as for qualitative and quantitative analyses of crude alkaloid extracts of Rauvolfia serpentina X Rhazya stricta hybrid cell cultures. The developed conditions for CE analysis proved to be efficient for separation of mixtures of standard indole and beta-carboline alkaloids. The described buffer system is also applicable in the combination of CE with electrospray ionisation mass spectrometry. This analytical technique allowed the separation and identification of components of standard indole alkaloid mixture as well as crude extracts of R. serpentina roots, R. serpentina cell suspension cultures and cortex of Aspidosperma quebracho-blanco. The influence of buffer composition and analyte structures on separation is discussed. PMID:12219932

  13. Comparison of four C18 columns for the liquid chromatographic determination of deoxynivalenol in naturally contaminated wheat.

    PubMed

    Abdel-Aal, El-Sayed M; Miah, Kaddus; Young, J Christopher; Rabalski, Iwona

    2007-01-01

    Three long and 1 short reversed-phase C18 columns were compared for separation of deoxynivalenol (DON) in extracts of naturally contaminated wheat samples using liquid chromatography with ultraviolet detection and liquid chromatography/mass spectrometry (LC/MS). Among the 3 long columns used, a Symmetry C18 column with an isocratic solvent mixture of water-acetonitrile-methanol (90 + 5 + 5, v/v/v) gave the best separation for DON without interferences from other compounds in the wheat extracts. The Symmetry short (75 mm) column was comparable with the long column (250 mm) in resolving DON but significantly reduced retention time (i.e., 5.8 versus 16.3 min). Increasing the column temperature from 25 to 45 degrees C resulted in a further reduction in retention time. Identity of DON in the wheat extracts and standard solutions was confirmed by LC/MS in the positive ion mode, whereby DON appeared with an (M+1)+ ion at a mass-to-charge ratio of 297 plus fragment ions associated with loss of water and/or a 30 atomic mass unit (amu) CH2O fragment. The Symmetry short column was also capable of separating a mixture of the mycotoxins DON, 15-acetyl-DON, nivalenol, and zearalenone by use of a combination of an isocratic and gradient solvent system. The overall method showed high precision, exhibiting a relative standard deviation of 4.8%, limit of detection of 50 ng/g, and limit of quantitation of 165 ng/g. It was significantly correlated with enzyme-linked immunosorbent assay analysis, indicating its appropriateness for safety and quality assurance of wheat and related grains. PMID:17760337

  14. Coal liquefaction process streams characterization and evaluation: Application of liquid chromatographic separation methods to THF-soluble portions of integrated two-stage coal liquefaction resids

    SciTech Connect

    Green, J.B.; Pearson, C.D.; Young, L.L.; Green, J.A. )

    1992-05-01

    This study demonstrated the feasibility of using non-aqueous ion exchange liquid chromatography (NIELC) for the examination of the tetrahydrofuran (THF)-soluble distillation resids and THF-soluble whole oils derived from direct coal liquefaction. The technique can be used to separate the material into a number of acid, base, and neutral fractions. Each of the fractions obtained by NIELC was analyzed and then further fractionated by high-performance liquid chromatography (HPLC). The separation and analysis schemes are given in the accompanying report. With this approach, differences can be distinguished among samples obtained from different process streams in the liquefaction plant and among samples obtained at the same sampling location, but produced from different feed coals. HPLC was directly applied to one THF-soluble whole process oil without the NIELC preparation, with limited success. The direct HPLC technique used was directed toward the elution of the acid species into defined classes. The non-retained neutral and basic components of the oil were not analyzable by the direct HPLC method because of solubility limitations. Sample solubility is a major concern in the application of these techniques.

  15. Methods for describing airborne fractions of free fall spills of powders and liquids

    SciTech Connect

    Ballinger, M.Y.; Buck, J.W.; Owczarski, P.C.; Ayer, J.E.

    1988-01-01

    Pacific Northwest Laboratory developed calculational methods to characterize aerosols produced in hypothetical spill accidents. These methods were developed for the US Nuclear Regulatory Commission to use when evaluating the consequence of postulated accidents for safety analyses and environmental impact statements. Basic physical properties and mechanistic descriptions of spill events were used as a basis for the methods. Source term models consist of equations that can be used to estimate the mass airborne and particle size distribution of aerosols produced by spills of powders and solutions. Experimental data from Sutter et al. (1981) and Ballinger and Hodgson (1986) were emphasized in the models. Parameter ranges for this data were spill height 1 to 3 m, powder mass 25 to 1000 g, and liquid volume 125 to 1000 ml. Liquids spilled included slurries and solutions of varying viscosities. Liquid spills differed from powders in that an aerosol was produced on impact instead of during the fall. The fraction airborne from liquid spills (including viscous solutions and slurries) correlated well with three dimensionless numbers: the Archimedes number, the Froude number, and a density ratio. Liquid aerosol parameters were statistical descriptions of the log-normal distributions. A computer code was developed to model powder spills. In the code, the mass airborne was assumed proportional to the drag force on the power as it falls. The proportionality factor was empirically found to be a function of a dimensionless number, the Galileo number. 16 refs., 2 figs., 13 tabs.

  16. Microextraction by packed sorbent-high-pressure liquid chromatographic-ultra violet analysis of endocrine disruptor pesticides in various matrices.

    PubMed

    Kaur, Manpreet; Rani, Susheela; Malik, Ashok Kumar; Aulakh, Jatinder Singh

    2014-10-01

    Microextraction by a packed sorbent (MEPS) is the miniaturized version of solid-phase extraction whereby sample volumes as small as 10 μL can be used. A syringe (100-250 μL) is used in MEPS technique, which generally contains 4 mg of solid packing material inserted as a plug. The sample preparation occurs on the surface of this bed which can be modified to provide varied sampling conditions. In the present work, MEPS has been employed as a sample preparation technique for the analysis of endocrine disruptor (ED) and suspected ED pesticides in biological and environmental samples. The pesticides aldicarb, dimethoate, propazine and terbutryn have been successfully separated by high performance liquid chromatography-ultra violet (HPLC-UV) system with acetonitrile/water as the mobile phase in the ratio 60/40. Several factors affecting the performance of MEPS technique such as the number of extraction cycles, type of washing and elution solvent were optimized. This method has been applied to the analysis of these pesticides in urine, soil and tap water samples with good recoveries in the range of 81.4-97.8%. The detection limit ranged between 0.05 and 0.6 ng mL for the analyzed pesticides. PMID:24046162

  17. A high-performance liquid chromatographic assay with improved selectivity for cisplatin and active platinum (II) complexes in plasma ultrafiltrate.

    PubMed

    Andrews, P A; Wung, W E; Howell, S B

    1984-11-15

    cis-Diamminedichloroplatinum(II) (DDP) was measured in plasma ultrafiltrate following derivatization with sodium diethyldithiocarbamate (DDTC) by quantitation against a nickel chloride internal standard. A chloroform extract containing the Pt(DDTC)2 and Ni(DDTC)2 complexes was separated by reversed-phase high-performance liquid chromatography on a C18 radial compression column. The complex was eluted with methanol/water, 4/1, at a flow rate of 1.5 ml/min, and was detected at 254 nm. The limit of sensitivity was 0.1 microgram/ml DDP in the ultrafiltrate. This analytical approach was validated by comparison to graphite furnace atomic absorption spectrophotometric determinations of duplicate samples. There was clearly a component of the ultrafiltrable platinum present that was resistant to derivatization by DDTC. Evidence is presented that this component, presumably Pt(II) complexed with endogenous small molecules, is non cytotoxic and, hence, that this method may be selective for "active Pt(II)." This method offers an advantage over atomic absorption determination of total platinum in ultrafiltrate which does not discriminate between active and inactive forms, and over off-line FAA detection of parent DDP in HPLC eluates which ignores other active forms. Using this technique we have measured the pharmacokinetics of DDTC-reactive Pt(II) in humans after either i.v. infusion or infusion of DDP into the peritoneal cavity of patients with ovarian carcinoma. PMID:6099065

  18. Novel stereoselective high-performance liquid chromatographic method for simultaneous determination of guaifenesin and ketorolac enantiomers in human plasma.

    PubMed

    Maher, Hadir M; Al-Taweel, Shorog M; Alshehri, Mona M; Alzoman, Nourah Z

    2014-10-01

    A novel method was developed for the simultaneous determination of guaifenesin (GUA) and ketorolac tromethamine (KET) enantiomers in plasma samples. Since GUA probably increases the absorption of coadministered drugs (e.g., KET), it would be extremely important to monitor KET plasma levels for the purpose of dose adjustment with a subsequent decrease in the side effects. Enantiomeric resolution was achieved on a polysaccharide-based chiral stationary phase, amylose-2, as a chiral selector under the normal phase (NP) mode and using ornidazole (ORN) as internal standard. This innovative method has the advantage of the ease and reliability of sample preparation for plasma samples. Sample clean-up was based on simply using methanol for protein precipitation followed by direct extraction of drug residues using ethanol. Both GUA and KET enantiomers were separated using an isocratic mobile phase composed of hexane/isopropanol/trifluoroacetic acid, 85:15:0.05 v/v/v. Peak area ratios were linear over the range 0.05-20 µg/mL for the four enantiomers S (+) GUA, R (-) GUA, R (+) KET, and S (-) KET. The method was fully validated according to the International Conference on Harmonization (ICH) guidelines in terms of system suitability, specificity, accuracy, precision, robustness, and solution stability. Finally, this procedure was innovative to apply the rationale of developing a chiral high-performance liquid chromatography (HPLC) procedure for the simultaneous quantitative analysis of drug isomers in clinical samples. PMID:25043279

  19. Matrix solid-phase dispersion extraction and high-performance liquid chromatographic determination of residual sulfonamides in chicken.

    PubMed

    Kishida, K; Furusawa, N

    2001-12-01

    Simultaneous determination of the six sulfonamides (SAs) sulfadiazine, sulfadimidine, sulfamonomethoxine, sulfamethoxazole, sulfadimethoxine and sulfaquinoxaline in chicken using matrix solid-phase dispersion (MSPD) with neutral aluminium oxide as an MSPD sorbent and high-performance liquid chromatography (HPLC) is presented. In the present MSPD, six SAs could be isolated by only one step, elution with a 70% (v/v) aqueous ethanol solution, without the sorbent conditioning and the sorbent-tissue matrix washing. For the HPLC determination, a LiChrospher 100 RP-8 and a mixture of 1% acetic acid solution (pH 3.0, in water)-acetonitrile-N,N-dimethylformamide (78:22:5, v/v/v) as the mobile phase with a photodiode array detector were used. Average recoveries were greater than 87.6% with relative standard deviations between 0.5 and 8.6%. The total time and amount of solvent required for the analysis of one sample were <1.5 h and <12 ml, respectively. PMID:11765084

  20. Supercritical fluid carbon dioxide extraction and liquid chromatographic separation with electrochemical detection of methylmercury from biological samples

    USGS Publications Warehouse

    Simon, N.S.

    1997-01-01

    Using the coupled methods presented in this paper, methylmercury can be accurately and rapidly extracted from biological samples by modified supercritical fluid carbon dioxide and quantitated using liquid chromatography with reductive electrochemical detection. Supercritical fluid carbon dioxide modified with methanol effectively extracts underivatized methylmercury from certified reference materials Dorm-1 (dogfish muscle) and Dolt-2 (dogfish liver). Calcium chloride and water, with a ratio of 5:2 (by weight), provide the acid environment required for extracting methylmercury from sample matrices. Methylmercury chloride is separated from other organomercury chloride compounds using HPLC. The acidic eluent, containing 0.06 mol L-1 NaCl, insures the presence of methylmercury chloride and facilitates the reduction of mercury on a glassy carbon electrode. If dual glassy carbon electrodes are used, a positive peak is observed at -0.65 to -0.70 V and a negative peak is observed at -0.90V with the organomercury compounds that were tested. The practical detection limit for methylmercury is 5 X 10-8 mol L-1 (1 X 10-12 tool injected) when a 20 ??L injection loop is used.

  1. Liquid chromatographic profiles of major carotenoid esters in commercially processed California Navel and Valencia orange juice concentrates.

    PubMed

    Philip, T; Chen, T S; Nelson, D B

    1988-06-17

    A procedure for establishing profiles of major carotenoid esters in commercially processed Valencia and Navel orange juice concentrates by reversed-phase liquid chromatography (LC) using Sudan 1 as internal standard is described. The procedure involved conversion of 5,6-epoxides in heat concentrated citrus juices to more stable 5,8-epoxides by treatment of extracted carotenoids with hydrochloric acid followed by dual wavelength analyses at 400 and 465 nm using LC. The esters of 5,8-furanoids (auroxanthin and mutatoxanthin) were approximately quantitated at 400 nm without interference from other carotenoids. Cryptoxanthin esters and free cryptoxanthin, lutein esters, citraurin esters and carotenes were approximately quantitated at 465 nm without interference from auroxanthin esters. The furanoid esters varied from 60 to 75% of the total carotenoids in the concentrates. The cryptoxanthin esters varied from 5 to 10% of the total carotenoids in Valencia orange juice concentrates and from 10 to 15% of the total carotenoids in Navel orange juice concentrates. Citraurin esters were present only in Navel orange juice concentrates and beta-carotene content was less than 5% of the total carotenoids in both concentrates. The total carotenoids and individual carotenoids increased with the advance in season in Navel orange juice concentrates which had less than half the amount of total carotenoids of Valencia orange juice concentrates. PMID:3417817

  2. High-Performance Liquid Chromatographic Determination of Propofol in Human Plasma: Comparison of Different Heteroscedastic Calibration Curve Models

    PubMed Central

    Taghavi Moghaddam, Pooria; Pipelzadeh, Mohammad Reza; Nesioonpour, Sholeh; Saki, Nader; Rezaee, Saeed

    2014-01-01

    Purpose: The aim of this study was to select the best calibration model for determination of propofol plasma concentration by high-performance liquid chromatography method. Methods: Determination of propofol in plasma after deproteinization with acetonitrile containing thymol (as internal standard) was carried out on a C18 column with a mixture of acetonitrile and trifluoroacetic acid 0.1% (60:40) as mobile phase which delivered at the flow rate of 1.2 mL/minute . Fluorescence detection was done at the excitation and emission wavelengths of 276 and 310 nm, respectively. After fitting different equations to the calibration data using weighted regression, the adequacy of models were assessed by lack-of-fit test, significance of all model parameters, adjusted coefficient of determination (R2adjusted) and by measuring the predictive performance with median relative prediction error and median absolute relative prediction error of the validation data set. Results: The best model was a linear equation without intercept with median relative prediction error and median absolute relative prediction error of 4.0 and 9.4%, respectively in the range of 10-5000 ng/mL. The method showed good accuracy and precision. Conclusion: The presented statistical framework could be used to choose the best model for heteroscedastic calibration data for analytes like propofol with wide range of expected concentration. PMID:25436190

  3. Liquid chromatographic determination of tilmicosin in swine feed at 200-400 mg/kg level: interlaboratory study.

    PubMed

    Readnour, R S; Coleman, M R; Leadbetter, M G

    1997-01-01

    An analytical method for the determination of tilmicosin at 200-400 mg/kg, the intended use concentration range, was evaluated in an interlaboratory study involving 5 laboratories, including the sponsor. The interlaboratory study evaluated the intra- and interlaboratory precision and accuracy of a tilmicosin feed method. The method procedure involved extracting tilmicosin from feed by adding 200 mL extractant to 20 g feed and shaking for 1 h. The extract is filtered and analyzed by gradient liquid chromatography which separates tilmicosin from feed matrix in 30 min. Each laboratory assayed 5 replicates of fortified feed at concentrations of 0, 100, 200, 400, and 600 mg/kg. The mean recovery among fortified samples ranged from 81.4 to 98.8%, with a percent coefficient of variation (%CV) ranging from 0.3 to 4.0%. For all blank control feed samples no significant interferences were observed. In addition, each laboratory assayed 5 replicates of medicated feed samples prepared at 2 levels (200 and 400 mg/kg) with either a horizontal or vertical mixer. Along with the medicated feed samples were included 5 replicates of a blank control feed. The identities of the medicated and blank control feed samples were blinded to the analysts. The results for the medicated feed samples ranged from 95.8 to 106% of label claim, with a %CV ranging from 2.1 to 6.7%. PMID:9419853

  4. High performance liquid chromatographic analysis and anticancer potential of Oplopanax horridus: Comparison of stem and berry extracts

    PubMed Central

    Wang, Chong-Zhi; Aung, Han H.; Mehendale, Sangeeta R.; Shoyama, Yukihiro; Yuan, Chun-Su

    2009-01-01

    Oplopanax horridus or devil’s club is a herbal medicine distributed in North America. The constituents and pharmacological activities of O. horridus (OPH) are largely unknown. In this study, we assayed OPH stem and berry extracts using high performance liquid chromatography (HPLC). The anticancer potentials of extracts on different human cancer cell lines (SW-480, HCT-116, HT-29, MCF-7 and NSCLC) were determined by MTS method. The effect of stem extract on cancer cell cycle, expression of cyclin A, and apoptosis were assayed using flow cytometry. HPLC data showed that the composition of OPH stem extract is more complicated than the berry extract. The wavelength of maximum absorption of the major constituent in stem and berry is 196.0 nm and 201.9 nm, respectively. Compared to the berry extract, the stem extract showed significant potent antiproliferative effect on all the studied cell lines. The stem extract at 0.1 mg/ml arrested cancer cells in S- and G2/M-phases, and significantly induced expression of cyclin A. After treatment with 0.1 mg/ml of stem extract for 72 h, apoptotic cells were increased to 45.2%, while control was 9.6%. The cell cycle arrest and induction of apoptosis may play a critical role in cancer chemoprevention by Oplopanax horridus stem extract. PMID:19686820

  5. Determination of stimulants in a single human hair sample by high-performance liquid chromatographic method with chemiluminescence detection.

    PubMed

    Takayama, N; Tanaka, S; Hayakawa, K

    1997-01-01

    Stimulants that are controlled by the Stimulant Drug Control Law of Japan are methamphetamine (MA) and amphetamine (AP). MA is used by most stimulant addicts, and AP is detected as its main metabolite. We have developed a high-performance liquid chromatography method with chemiluminescence detection (CL-HPLC), for determining trace levels of MA and its metabolites in a single human hair sample, in which bis(2,4,6-trichlorophenyl)oxalate and hydrogen peroxide are the postcolumn reagents. After washing a single hair sample with water and methanol, it was cut into pieces, extracted with a mixed solution of methanol and hydrochloric acid for 1 h under ultra-sonication and allowed to stand at room temperature overnight. Then the organic phase was evaporated to dryness. To the residues, 0.1 mL of carbonate buffer and 0.1 mL of dansyl chloride solution were added and the solution was heated at 45 degrees C for 1 h. An aliquot of the reaction mixture was then subjected to HPLC. MA and AP were chemiluminogenically detected as their dansyl derivatives from a sample of only a single hair. The detection limit was about 2 pg in an injected volume (20 microliters), and about 20 pg in a single hair sample. This detection limit was smaller than that by the gas chromatography/mass spectrometry (selective ion monitoring) method. Our method was useful as a screening test for stimulant users. PMID:9051212

  6. High performance liquid chromatographic determination of vitamin A in margarine, milk, partially skimmed milk, and skimmed milk.

    PubMed

    Thompson, J N; Hatina, G; Maxwell, W B

    1980-07-01

    Saponification and subsequent evaporation of extracts can cause losses of vitamin A during analysis and thus cause erratic results. These steps were therefore avoided by measuring retinyl palmitate and beta-carotene directly in hexane extracts of milk and margarine. Extracts were purified before high performance liquid chromatography (HPLC) by washing with aqueous alcohol. Retinyl palmitate was measured at 325 nm after chromatography on LiChrosorb Si60, 5 micrometer, using ethyl ether-hexane (2+98) as the solvent system. Milk (2 mL) was shaken with absolute ethanol (5 mL) and hexane (5 mL). Water (3 mL) was added and, after mixing and centrifugation, 100 microL hexane hexane layer was injected. Margarine (5 g) was dissolved in hexane (100 mL). After 5 mL of the hexane solution was washed with 60% ethanol and centrifuged, a 50 microL aliquot was injected. The results of the retinyl palmitate estimation in milk agreed with those obtained by a fluorometric method; the results in margarine agreed with those obtained by saponification, extraction, and HPLC. The coefficients of variation on analysis of 10 replicate samples of milk and margarine were 3 and 4.5%, respectively. The analysis of margarine for vitamin A was completed by measuring beta-carotene with a detector set at 453 nm; the coefficient of variation of this measurement was 3% (10 replicates). PMID:7400091

  7. Development and validation of a high-performance liquid chromatographic method for the determination of cyproterone acetate in human skin.

    PubMed

    Henry de Hassonville, Sandrine; Chiap, Patrice; Liégeois, Jean-François; Evrard, Brigitte; Delattre, Luc; Crommen, Jacques; Piel, Géraldine; Hubert, Philippe

    2004-09-21

    In the framework of a preliminary study on the transdermal penetration of cyproterone acetate (CPA), a simple and rapid procedure involving an extraction step coupled to a HPLC-UV determination has been developed for the separation and quantification of CPA in the two main skin layers-epidermis and dermis-after local application. The separation of epidermis and dermis layers was carefully carried out by means of a sharp spatula after skin immersion in heated water at 65 degrees C. The two skin layers were then treated separately according to the same process: (1) sample homogenization by vibration after freezing with liquid nitrogen in a Mikro-Dismembrator; (2) CPA extraction with methanol after addition of the internal standard (betamethasone dipropionate); (3) centrifugation; (4) evaporation of a supernatant aliquot; (5) dissolution of the dry residue in methanol and addition of water; (6) centrifugation; (7) injection of a supernatant aliquot into the HPLC system. The separation was achieved on octadecylsilica stationary phase using a mobile phase consisting in a mixture of acetonitrile and water (40:60 (v/v)). The method was then validated using a new approach based on accuracy profiles over a CPA concentration range from 33 to 667 ng/ml for each skin layer. Finally, the method was successfully applied to the determination of CPA to several skin samples after topical application of different gel formulations containing CPA. PMID:15351057

  8. Improvement of the chromatographic separation performance of an imidazolium ionic liquid functionalized silica column by in situ anion-exchange with dodecyl sulfonate and dodecylbenzene sulfonate anions.

    PubMed

    Sun, Min; Feng, Juanjuan; Chen, Wenjie; Li, Leilei; Duan, Huimin; Luo, Chuannan

    2014-06-01

    The anionic part of ionic liquids can provide additional interactions during chromatographic separations. In this work, the chromatographic separation performance of a silica column functionalized with 1-propyl-3-methylimidazolium chloride ionic liquid was improved by in situ anion-exchange from chloride anions to dodecyl sulfonate anions and dodecylbenzene sulfonate anions. The separation performances of these ionic liquid functionalized phases were investigated and compared with each other using polycyclic aromatic hydrocarbons, phthalates, parabens, and phenols as model compounds. Results indicated that the new columns presented a better chromatographic separation than the original one. This was ascribed retention mechanism from organic anions. The introduction of dodecyl sulfonate anions increased the hydrophobicity of stationary phase. Furthermore, the phenyl groups of dodecylbenzene sulfonate anions could provide an enhanced selectivity to aromatic compounds such as polycyclic aromatic hydrocarbons by π-π interactions. Analysis repeatability of the new columns was satisfactory (RSD of retention time, 0.10-0.40%; RSD of peak area, 0.66-0.84%). PMID:24616155

  9. Liquid-Vapor Equilibrium Isotopic Fractionation of Water. How well can classical water models predict it?

    SciTech Connect

    Chialvo, Ariel A; Horita, Juske

    2009-01-01

    The liquid-vapor equilibrium isotopic fractionation of water is determined by molecular-based simulation, via Gibbs Ensemble Monte Carlo and isothermal-isochoric molecular dynamics involving two radically different but realistic models, the extended simple point charge (SPC/E) and the Gaussian charge polarizable (GCP) models. The predicted temperature dependence of the liquid-vapor equilibrium isotopic fractionation factors for H 2 18O / H 2 16O, H 2 17O / H 2 16O, and 2H 1H 16O / 1H 2 16O are compared against the most accurate experimental datasets to assess the ability of these intermolecular potential models to describe quantum effects according to the Kirkwood-Wigner free energy perturbation ! 2 !expansion. Predictions of the vapor pressure isotopic effect for the H 2 18O / H 2 16O and H 2 17O / H 2 16O pairs are also presented in comparison with experimental data and two recently proposed thermodynamic modeling approaches. Finally, the simulation results are used to discuss some approximations behind the microscopic interpretation of isotopic fractionation based on the underlying roto-translational coupling.

  10. Chemical class fractionation and thermophysical property measurements of solvent refined coal liquids

    SciTech Connect

    Hewitt, J.D.; Rodgers, B.R.

    1980-01-01

    Coal liquids are a potpourri of organic molecules and inorganic particles; they cannot be considered as a single entity because of variations in coals and processing conditions during conversion to liquids. A method of solubility class fractionation originally developed for petroleum asphalts was adapted to coal liquids. The component classes - asphaltols, asphaltenes, resins, and oils - were separated according to their solubilities in benzene, pentane, and propane. Important physical and thermodynamic properties (viscosity, density, dielectric constant, and conductivity) of these fractions were determined as a function of temperature. In many cases these are the only values currently available to other investigators and are much in demand. We observed that density was most affected by the solids, as expected; however, the dielectric constant was most affected by the asphaltols, the viscosity by the resins (closely followed by the asphaltenes), and the conductivity by the resins. This led to the conclusion that the asphaltols contain the most polarizable material and the resins the most ionizable material. The conductivity remaining after all these materials were removed (10/sup -9/ mho/cm) and the dielectric constant (4.5) are still significantly higher than the corresponding values for most pure hydrocarbons and are important characteristics of these materials.

  11. Emergent Chiral Spin Liquid: Fractional Quantum Hall Effect in a Kagome Heisenberg Model

    PubMed Central

    Gong, Shou-Shu; Zhu, Wei; Sheng, D. N.

    2014-01-01

    The fractional quantum Hall effect (FQHE) realized in two-dimensional electron systems under a magnetic field is one of the most remarkable discoveries in condensed matter physics. Interestingly, it has been proposed that FQHE can also emerge in time-reversal invariant spin systems, known as the chiral spin liquid (CSL) characterized by the topological order and the emerging of the fractionalized quasiparticles. A CSL can naturally lead to the exotic superconductivity originating from the condense of anyonic quasiparticles. Although CSL was highly sought after for more than twenty years, it had never been found in a spin isotropic Heisenberg model or related materials. By developing a density-matrix renormalization group based method for adiabatically inserting flux, we discover a FQHE in a isotropic kagome Heisenberg model. We identify this FQHE state as the long-sought CSL with a uniform chiral order spontaneously breaking time reversal symmetry, which is uniquely characterized by the half-integer quantized topological Chern number protected by a robust excitation gap. The CSL is found to be at the neighbor of the previously identified Z2 spin liquid, which may lead to an exotic quantum phase transition between two gapped topological spin liquids. PMID:25204626

  12. Emergent Chiral Spin Liquid: Fractional Quantum Hall Effect in a Kagome Heisenberg Model

    NASA Astrophysics Data System (ADS)

    Gong, Shou-Shu; Zhu, Wei; Sheng, D. N.

    2014-09-01

    The fractional quantum Hall effect (FQHE) realized in two-dimensional electron systems under a magnetic field is one of the most remarkable discoveries in condensed matter physics. Interestingly, it has been proposed that FQHE can also emerge in time-reversal invariant spin systems, known as the chiral spin liquid (CSL) characterized by the topological order and the emerging of the fractionalized quasiparticles. A CSL can naturally lead to the exotic superconductivity originating from the condense of anyonic quasiparticles. Although CSL was highly sought after for more than twenty years, it had never been found in a spin isotropic Heisenberg model or related materials. By developing a density-matrix renormalization group based method for adiabatically inserting flux, we discover a FQHE in a isotropic kagome Heisenberg model. We identify this FQHE state as the long-sought CSL with a uniform chiral order spontaneously breaking time reversal symmetry, which is uniquely characterized by the half-integer quantized topological Chern number protected by a robust excitation gap. The CSL is found to be at the neighbor of the previously identified Z2 spin liquid, which may lead to an exotic quantum phase transition between two gapped topological spin liquids.

  13. Quantification of rifapentine, a potent antituberculosis drug, from dried blood spot samples using liquid chromatographic-tandem mass spectrometric analysis.

    PubMed

    Parsons, Teresa L; Marzinke, Mark A; Hoang, Thuy; Bliven-Sizemore, Erin; Weiner, Marc; Mac Kenzie, William R; Dorman, Susan E; Dooley, Kelly E

    2014-11-01

    The quantification of antituberculosis drug concentrations in multinational trials currently requires the collection of modest blood volumes, centrifugation, aliquoting of plasma, freezing, and keeping samples frozen during shipping. We prospectively enrolled healthy individuals into the Tuberculosis Trials Consortium Study 29B, a phase I dose escalation study of rifapentine, a rifamycin under evaluation in tuberculosis treatment trials. We developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantifying rifapentine in whole blood on dried blood spots (DBS) to facilitate pharmacokinetic/pharmacodynamic analyses in clinical trials. Paired plasma and whole-blood samples were collected by venipuncture, and whole blood was spotted on Whatman protein saver 903 cards. The methods were optimized for plasma and then validated for DBS. The analytical measuring range for quantification of rifapentine and its metabolite was 50 to 80,000 ng/ml in whole-blood DBS. The analyte was stable on the cards for 11 weeks with a desiccant at room temperature and protected from light. The method concordance for paired plasma and whole-blood DBS samples was determined after correcting for participant hematocrit or population-based estimates of bias from Bland-Altman plots. The application of either correction factor resulted in acceptable correlation between plasma and whole-blood DBS (Passing-Bablok regression corrected for hematocrit; y = 0.98x + 356). Concentrations of rifapentine may be determined from whole-blood DBS collected via venipuncture after normalization in order to account for the dilutional effects of red blood cells. Additional studies are focused on the application of this methodology to capillary blood collected by finger stick. The simplicity of processing, storage, shipping, and low blood volume makes whole-blood DBS attractive for rifapentine pharmacokinetic evaluations, especially in international and pediatric trials. PMID:25182637

  14. Comparison of chromatographic band profiles obtained under microwave irradiated and non-irradiated reversed-phase liquid chromatography column

    SciTech Connect

    Galinada, Wilmer; Guiochon, Georges A

    2005-08-01

    The possible influence of the application of microwave energy to a reversed-phase liquid chromatography column on the mass transfer kinetics and the thermodynamics of equilibrium between mobile and stationary phases was examined. Chromatograms of propylbenzene and phenol were recorded under the same experimental conditions, on the same column, successively irradiated and not. The effect of microwave irradiation on the mass transfer kinetics was determined by measuring the second moment of small pulses of propylbenzene in a 70:30 (v/v) solution of methanol in water and microwave outputs of 15 and 30 W. The effect of microwave irradiation on the equilibrium thermodynamics was determined by measuring the elution time of breakthrough curves of phenol at high concentrations in a 20:80 (v/v) solution of methanol and water and microwave outputs of 15, 50, and 150 W. A qualitative comparison of the profiles of the propylbenzene peaks obtained with and without irradiation suggests that this irradiation affects significantly the peak shapes. However, a qualitative comparison of the profiles of the breakthrough curves of phenol obtained with and without irradiation suggests that this irradiation has no significant effect on their shapes. The peak sharpening observed may be due to an increase in the diffusivity, resulting from the dielectric polarization under microwave irradiation. This effect is directly related to an increase of the rate of mass transfers in the column. In contrast, the similarity of the overloaded band profiles at high concentrations suggests that the equilibrium thermodynamics is unaffected by microwave irradiation. This may be explained by the transparence of the stationary phase to microwaves at 2.45 GHz. The column temperature was measured at the column outlet under irradiation powers of 15, 30, 50, and 150 W. It increases with increasing power, the corresponding effluent temperatures being 25 {+-} 1, 30 {+-} 1, 35 {+-} 1, and 45 {+-} 1 C, respectively.

  15. A fast liquid chromatographic tandem mass spectrometric method for the simultaneous determination of total homocysteine and methylmalonic acid.

    PubMed

    Hempen, Christel; Wanschers, Harry; van der Sluijs Veer, Gertjan

    2008-05-01

    A liquid chromatography(LC)/electrospray ionization tandem mass spectrometry (MS) method for the quantitative determination of total homocysteine and methylmalonic acid and the monitoring of methionine, homocystine and succinic acid in plasma has been developed. The analytes are determined under the presence of the deuterated internal standards methylmalonic acid-d (3) and homocystine-d (8). Although methylmalonic acid can be determined directly, a reduction step has to be carried out to ensure the measurement of total homocysteine. Ultrafiltration was applied afterwards to deproteinize the samples prior to LC/MS injection. LC/MS analysis is carried out isocratically using a mobile phase consisting of 5% methanol and 95% of a 0.06 M formic acid solution on a reversed-phase C18 column at a flow rate of 0.5 mL/min. The MS measurement was separated into several periods: homocysteine, homocystine and methionine were determined in the positive-ion mode, whereas the determinations of methylmalonic acid and succinic acid were carried out in the negative-ion mode. The intraday coefficients of variation (CVs) were 2.9% or less and 3.2% or less for homocysteine and methylmalonic acid, respectively. Interday CVs ranged from 3.8 to 5.9% for homocysteine and from 3.5 to 6.3% for methylmalonic acid. Analyte concentrations could reliably be determined, also far below the reference values. Furthermore, the linearity was determined and a correlation study with respect to the existing homocysteine and methylmalonic acid methods at Medisch Spectrum Twente Hospital was carried out. PMID:18368393

  16. Quantification of Rifapentine, a Potent Antituberculosis Drug, from Dried Blood Spot Samples Using Liquid Chromatographic-Tandem Mass Spectrometric Analysis

    PubMed Central

    Parsons, Teresa L.; Marzinke, Mark A.; Hoang, Thuy; Bliven-Sizemore, Erin; Weiner, Marc; Mac Kenzie, William R.; Dorman, Susan E.

    2014-01-01

    The quantification of antituberculosis drug concentrations in multinational trials currently requires the collection of modest blood volumes, centrifugation, aliquoting of plasma, freezing, and keeping samples frozen during shipping. We prospectively enrolled healthy individuals into the Tuberculosis Trials Consortium Study 29B, a phase I dose escalation study of rifapentine, a rifamycin under evaluation in tuberculosis treatment trials. We developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantifying rifapentine in whole blood on dried blood spots (DBS) to facilitate pharmacokinetic/pharmacodynamic analyses in clinical trials. Paired plasma and whole-blood samples were collected by venipuncture, and whole blood was spotted on Whatman protein saver 903 cards. The methods were optimized for plasma and then validated for DBS. The analytical measuring range for quantification of rifapentine and its metabolite was 50 to 80,000 ng/ml in whole-blood DBS. The analyte was stable on the cards for 11 weeks with a desiccant at room temperature and protected from light. The method concordance for paired plasma and whole-blood DBS samples was determined after correcting for participant hematocrit or population-based estimates of bias from Bland-Altman plots. The application of either correction factor resulted in acceptable correlation between plasma and whole-blood DBS (Passing-Bablok regression corrected for hematocrit; y = 0.98x + 356). Concentrations of rifapentine may be determined from whole-blood DBS collected via venipuncture after normalization in order to account for the dilutional effects of red blood cells. Additional studies are focused on the application of this methodology to capillary blood collected by finger stick. The simplicity of processing, storage, shipping, and low blood volume makes whole-blood DBS attractive for rifapentine pharmacokinetic evaluations, especially in international and pediatric trials. PMID:25182637

  17. Chromatographic evaluation of a newly designed peptide-silica stationary phase in reverse phase liquid chromatography and hydrophilic interaction liquid chromatography: mixed mode behavior.

    PubMed

    Ray, Sudipta; Takafuji, Makoto; Ihara, Hirotaka

    2012-11-30

    The short peptide Boc-Phe-Aib-Phe-OH was synthesized and immobilized onto porous silica using grafting methodology. The resulting peptide-bonded silica was characterized using DRIFT-mode FT-IR, elemental analysis, thermogravimetric analysis, solid state C(13) NMR spectroscopy and the successful immobilization of the peptide on the silica support was confirmed. This grafted phase was packed into a stainless steel column and used for mixed-mode chromatography such as reversed-phase high-performance liquid chromatography and hydrophilic interaction liquid chromatography for the efficient separation of hydrophobic compounds, small polar molecules, and drug molecules. Compared with ODS and phenyl columns, this new stationary phase shows considerably higher molecular-planarity selectivity towards polyaromatic hydrocarbons and also available for separation of nucleo-analytes and sulfa-drug molecules in a hydrophilic interaction liquid chromatography mode. The multiple interactions induced by polar carbonyl group and hydrophobic phenyl group allow this peptide-modified silica to serve as a multi-mode stationary phase in high performance liquid chromatography. PMID:23116801

  18. Acoustic wave absorption as a probe of dynamical geometrical response of fractional quantum Hall liquids

    NASA Astrophysics Data System (ADS)

    Yang, Kun

    2016-04-01

    We show that an acoustic crystalline wave gives rise to an effect similar to that of a gravitational wave to an electron gas. Applying this idea to a two-dimensional electron gas in the fractional quantum Hall regime, this allows for experimental study of its intra-Landau level dynamical response in the long-wavelength limit. To study such response we generalize Haldane's geometrical description of fractional quantum Hall states to situations where the external metric is time dependent. We show that such time-dependent metric (generated by acoustic wave) couples to collective modes of the system, including a quadrapolar mode at long wavelength, and magnetoroton at finite wavelength. Energies of these modes can be revealed in spectroscopic measurements, controlled by strain-induced Fermi velocity anisotropy. We argue that such geometrical probe provides a potentially highly useful alternative probe of quantum Hall liquids, in addition to the usual electromagnetic response.

  19. Serodiagnosis of fasciolosis by fast protein liquid chromatography-fractionated excretory/secretory antigens.

    PubMed

    Mokhtarian, Kobra; Akhlaghi, Lame; Meamar, Ahmad Reza; Razmjou, Elham; Manouchehri Naeini, Kourosh; Gholami, Samaneh; Najafi Samei, Masoomeh; Falak, Reza

    2016-08-01

    In several studies, different antigenic preparations and diverse immunological tests were applied for serodiagnosis of Fasciola hepatica infections. Most of these preparations showed cross-reactivity with proteins of other parasites. Application of purified antigens might reduce these cross-reactivities. Here, we used fast protein liquid chromatography (FPLC)-fractionated extracts of F. hepatica excretory/secretory antigens (E/S Ags) for serodiagnosis of human and sheep fasciolosis. To develop an improved diagnostic method, we fractionated F. hepatica E/S Ags by anion exchange chromatography on a Sepharose CL-6B column and then tested the serodiagnostic values of the fractions. We used sera from F. hepatica-infected human and sheep as positive controls. Sera from patients with hydatidosis and strongyloidiasis were used for cross-reactivity studies. Enzyme-linked immunosorbent assays (ELISA) of the second FPLC peak, containing 20, 25, and 70 kDa proteins, discriminated between F. hepatica-infected and uninfected human and sheep samples. Fractionation of F. hepatica E/S Ags by FPLC is a fast and reproducible way of obtaining antigens useful for serodiagnosis of human and sheep fasciolosis with acceptable sensitivity and specificity. Graphical abstract ᅟ. PMID:27130320

  20. Observation of Fractional Stokes-Einstein Behavior in the Simplest Hydrogen-bonded Liquid

    SciTech Connect

    Herwig, Kenneth W; Molaison, Jamie J; Fernandez-Alonso, F.; Bermejo, F. J.; Turner, John F. C.; McLain, Sylvia E.

    2007-01-01

    Quasielastic neutron scattering has been used to investigate the single-particle dynamics of hydrogen fluoride across its entire liquid range at ambient pressure. For T > 230 K, translational diffusion obeys the celebrated Stokes-Einstein relation, in agreement with nuclear magnetic resonance studies. At lower temperatures, we find significant deviations from the above behavior in the form of a power law with exponent xi = -0.71+/-0.05. More striking than the above is a complete breakdown of the Debye-Stokes-Einstein relation for rotational diffusion. Our findings provide the first experimental verification of fractional Stokes-Einstein behavior in a hydrogen-bonded liquid, in agreement with recent computer simulations.

  1. Liquid chromatographic-mass spectrometric method for simultaneous determination of small organic acids potentially contributing to acidosis in severe malaria.

    PubMed

    Sriboonvorakul, Natthida; Leepipatpiboon, Natchanun; Dondorp, Arjen M; Pouplin, Thomas; White, Nicholas J; Tarning, Joel; Lindegardh, Niklas

    2013-12-15

    Acidosis is an important cause of mortality in severe falciparum malaria. Lactic acid is a major contributor to metabolic acidosis, but accounts for only one-quarter of the strong anion gap. Other unidentified organic acids have an independent strong prognostic significance for a fatal outcome. In this study, a simultaneous bio-analytical method for qualitative and quantitative assessment in plasma and urine of eight small organic acids potentially contributing to acidosis in severe malaria was developed and validated. High-throughput strong anion exchange solid-phase extraction in a 96-well plate format was used for sample preparation. Hydrophilic interaction liquid chromatography (HILIC) coupled to negative mass spectroscopy was utilized for separation and detection. Eight possible small organic acids; l-lactic acid (LA), α-hydroxybutyric acid (aHBA), β-hydroxybutyric acid (bHBA), p-hydroxyphenyllactic acid (pHPLA), malonic acid (MA), methylmalonic acid (MMA), ethylmalonic acid (EMA) and α-ketoglutaric acid (aKGA) were analyzed simultaneously using a ZIC-HILIC column with an isocratic elution containing acetonitrile and ammonium acetate buffer. This method was validated according to U.S. Food and Drug Administration guidelines with additional validation procedures for endogenous substances. Accuracy for all eight acids ranged from 93.1% to 104.0%, and the within-day and between-day precisions (i.e. relative standard deviations) were lower than 5.5% at all tested concentrations. The calibration ranges were: 2.5-2500μg/mL for LA, 0.125-125μg/mL for aHBA, 7.5-375μg/mL for bHBA, 0.1-100μg/mL for pHPLA, 1-1000μg/mL for MA, 0.25-250μg/mL for MMA, 0.25-100μg/mL for EMA, and 30-1500μg/mL for aKGA. Clinical applicability was demonstrated by analyzing plasma and urine samples from five patients with severe falciparum malaria; five acids had increased concentrations in plasma (range LA=177-1169μg/mL, aHBA=4.70-38.4μg/mL, bHBA=7.70-38.0μg/mL, pHPLA=0.900-4.30

  2. Disclination Classes, Fractional Excitations, and the Melting of Quantum Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Gopalakrishnan, Sarang; Teo, Jeffrey C. Y.; Hughes, Taylor L.

    2013-07-01

    We consider how fractional excitations bound to a dislocation evolve as the dislocation is separated into a pair of disclinations. We show that some dislocation-bound excitations (such as Majorana modes and half-quantum vortices) are possible only if the elementary dislocation consists of two inequivalent disclinations, as is the case for stripes or square lattices but not for triangular lattices. The existence of multiple inequivalent disclination classes governs the two-dimensional melting of quantum liquid crystals (i.e., nematics and hexatics), determining whether superfluidity and orientational order can simultaneously vanish at a continuous transition.

  3. Thermal conductivity of simple liquids: temperature and packing-fraction dependence.

    PubMed

    Ohtori, Norikazu; Ishii, Yoshiki; Togawa, Yoshinori; Oono, Takuya; Takase, Keiichi

    2014-02-01

    The thermal conductivity of rare gases in liquid and dense fluid states has been evaluated using molecular dynamics simulation with the Lennard-Jones (LJ) potentials and the Green-Kubo (GK) formula. All the calculated thermal conductivities are in very good agreement with experimental results for a wide range of temperature and density. Special attention was paid to temperature and packing-fraction dependence which is nontrivial from dimensional analysis on the LJ potentials and the GK formula. First, the temperature dependence of T(1/4) was determined from the calculations at constant densities. Secondly, in order to obtain the dependence on packing fraction from that on number density separately, a scaling method of particle and/or cell size was introduced. The number density dependence of (N/V)(2/3) which is expected from the dimensional analysis of the GK formulas was confirmed and the packing-fraction dependence of η(3/2) was determined by using the scaling method. It turned out that the summarized functional form of m(-1/2)(N/V)(2/3)η(3/2)T(1/4) can well express both the calculated and experimental thermal conductivities for Ar, Kr, and Xe, where m is the atomic mass. The scaling method has also been applied to molten NaCl and KCl so that it has been found that the thermal conductivity has the packing-fraction dependence of η(2/3) which is much weaker than that of the simple LJ liquids. PMID:25353444

  4. Thermal conductivity of simple liquids: Temperature and packing-fraction dependence

    NASA Astrophysics Data System (ADS)

    Ohtori, Norikazu; Ishii, Yoshiki; Togawa, Yoshinori; Oono, Takuya; Takase, Keiichi

    2014-02-01

    The thermal conductivity of rare gases in liquid and dense fluid states has been evaluated using molecular dynamics simulation with the Lennard-Jones (LJ) potentials and the Green-Kubo (GK) formula. All the calculated thermal conductivities are in very good agreement with experimental results for a wide range of temperature and density. Special attention was paid to temperature and packing-fraction dependence which is nontrivial from dimensional analysis on the LJ potentials and the GK formula. First, the temperature dependence of T1/4 was determined from the calculations at constant densities. Secondly, in order to obtain the dependence on packing fraction from that on number density separately, a scaling method of particle and/or cell size was introduced. The number density dependence of (N/V)2/3 which is expected from the dimensional analysis of the GK formulas was confirmed and the packing-fraction dependence of η3/2 was determined by using the scaling method. It turned out that the summarized functional form of m-1/2(N/V)2/3η3/2T1/4 can well express both the calculated and experimental thermal conductivities for Ar, Kr, and Xe, where m is the atomic mass. The scaling method has also been applied to molten NaCl and KCl so that it has been found that the thermal conductivity has the packing-fraction dependence of η2/3 which is much weaker than that of the simple LJ liquids.

  5. Dynamic heterogeneity in crossover spin facilitated model of supercooled liquid and fractional Stokes-Einstein relation

    SciTech Connect

    Choi, Seo-Woo; Kim, Soree; Jung, YounJoon

    2015-06-28

    Kinetically constrained models have gained much interest as models that assign the origins of interesting dynamic properties of supercooled liquids to dynamical facilitation mechanisms that have been revealed in many experiments and numerical simulations. In this work, we investigate the dynamic heterogeneity in the fragile-to-strong liquid via Monte Carlo method using the model that linearly interpolates between the strong liquid-like behavior and the fragile liquid-like behavior by an asymmetry parameter b. When the asymmetry parameter is sufficiently small, smooth fragile-to-strong transition is observed both in the relaxation time and the diffusion constant. Using these physical quantities, we investigate fractional Stokes-Einstein relations observed in this model. When b is fixed, the system shows constant power law exponent under the temperature change, and the exponent has the value between that of the Frederickson-Andersen model and the East model. Furthermore, we investigate the dynamic length scale of our systems and also find the crossover relation between the relaxation time. We ascribe the competition between energetically favored symmetric relaxation mechanism and entropically favored asymmetric relaxation mechanism to the fragile-to-strong crossover behavior.

  6. Acoustic Monitor for Liquid-Solid Slurries Measurements at Low Weight Fractions

    SciTech Connect

    Dr. L.L. Tavlarides; Dr. A.S. Sangan

    2004-12-08

    The principle objective of the project was to develop an acoustic probe for determining the weight fraction of particles in a flowing suspension. The suspension can be solid-liquid (S-L) or solid-gas-liquid (S-G-L). The work accomplished during the first three years of DOE funding was devoted to the development of a rigorous theory for acoustic wave propagation through solid-liquid (S-L) and solid-gas-liquid (S-G-L). In the first funding period we developed an acoustic probe for S-G-L suspensions that has resulted in a theory, supported by our experiments, to describe small amplitude acoustic wave propagations in dilute suspensions (Norato, 1999; Spelter al., 1999, 2001: Norato et al. 2002). The theory agrees well with experimental data of sound attenuation over a wide range of particle sizes, frequencies, and weight percent solids. We have also completed theoretical and experimental investigation on the effect of entrained gas bubbles on the attenuation. This analysis permits us to determine the S-L weight percent in the presence of bubbles.

  7. Urine sample preparation of tricyclic antidepressants by means of a supported liquid membrane technique for high-performance liquid chromatographic analysis.

    PubMed

    Trocewicz, J

    2004-03-01

    Supported liquid membrane (SLM) technique for sample work-up and enrichment was used for determination of tricyclic antidepressant drugs in urine by high-performance liquid chromatography (HPLC) with UV detection. The studied antidepressant drugs were amitriptyline, opipramol, noxiptyline and additionally diethazine was used as possible internal standard. Alkaline phosphoric buffer with urine sample, as the donor solution, was passed over the liquid membrane into which investigated substances were extracted. On the other side of the membrane, analyzed compounds were trapped due to creating non-extractable form in acidic acceptor solution. Enriched and cleaned up drugs were then injected into a HPLC system with ultraviolet detection to analyze of their concentration in acceptor solution. Optimum extraction efficiency was determined by changing acceptor and donor solutions pH, application of different flow rates of donor solution and by using different solvents in the membrane. Also, donor solution volume, extraction time and concentration of analytes were varied to check the linearity of extraction process. The highest extraction efficiency: 43% for opipramol, 56% for noxiptyline, 43% for amitriptyline and 42% for diethazine (R.S.D. values were <6% and n=3) was achieved when 0.05 M phosphate buffer pH 4.0 and 9.5 were used as donor and acceptor solutions, respectively, n-undecane with 5% tri-n-octylphosphine oxide (TOPO) was used as liquid membrane. Limit of quantification (LOQ) for tricyclic antidepressants after enrichment of 100ml of urine sample was about 1 ng/ml. PMID:14751789

  8. Size Control and Fractionation of Ionic Liquid Filled Polymersomes with Glassy and Rubbery Bilayer Membranes.

    PubMed

    So, Soonyong; Lodge, Timothy P

    2016-05-17

    We demonstrate control over the size of ionic liquid (IL) filled polymeric vesicles (polymersomes) by three distinct methods: mechanical extrusion, cosolvent-based processing in an IL, and fractionation of polymersomes in a biphasic system of IL and water. For the representative ionic liquid (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([EMIM][TFSI])), the size and dispersity of polymersomes formed from 1,2-polybutadiene-b-poly(ethylene oxide) (PB-PEO) and polystyrene-b-poly(ethylene oxide) (PS-PEO) diblock copolymers were shown to be sensitive to assembly conditions. During mechanical extrusion through a polycarbonate membrane, the relatively larger polymersomes were broken up and reorganized into vesicles with mean size comparable to the membrane pore (100 nm radius); the distribution width also decreased significantly after only a few passes. Other routes were studied using the solvent-switch or cosolvent (CS) method, whereby the initial content of the cosolvent and the PEO block length of PS-PEO were systemically changed. The nonvolatility of the ionic liquid directly led to the desired concentration of polymersomes in the ionic liquid using a single step, without the dialysis conventionally used in aqueous systems, and the mean vesicle size depended on the amount of cosolvent employed. Finally, selective phase transfer of PS-PEO polymersomes based on size was used to extract larger polymersomes from the IL to the aqueous phase via interfacial tension controlled phase transfer. The interfacial tension between the PS membrane and the aqueous phase was varied with the concentration of sodium chloride (NaCl) in the aqueous phase; then the larger polymersomes were selectively separated to the aqueous phase due to differences in shielding of the hydrophobic core (PS) coverage by the hydrophilic corona brush (PEO). This novel fractionation is a simple separation process without any special apparatus and can help to prepare monodisperse polymersomes

  9. Comparison of ion-pairing and ion-suppressing liquid chromatographic methods for the determination of pyrimethamine and ormetoprim in chicken feed.

    PubMed

    Lin, Shih Yuh; Jeng, Shiow Lian

    2002-07-01

    A high-performance liquid chromatographic (HPLC) method is developed to simultaneously determine pyrimethamine (PYR) and ormetoprim (OMT) in chicken feed. In the ion-pairing HPLC determination of PYR and OMT, the relation between the retention factor (k') and the concentration of the organic phase (acetonitrile) shows a characteristic curve. The k' value first decreases and then increases slowly with increasing concentrations of acetonitrile, but then increases rapidly when the acetonitrile concentration increases to 90%. Resolutions (Rs) of PYR and OMT decrease gradually when the concentration of organic phase increases. Increasing the concentration of the pairing ion sodium 1-octanesulfonate (PIC B-8) can decrease the k' and Rs values. Optimum values of k' and Rs are obtained using 82% acetonitrile in 0.005 M PIC B-8. In ion-suppressing HPLC, varying the concentration of Na2HPO4 has little effect on either the k' or Rs values of PYR or OMT at pH 7.5. However, at pH 4.0, k' and Rs decline when the concentration of Na2HPO4 increases. In general, ion-pairing HPLC generates more satisfactory results than ion-suppressing HPLC. Using 82% acetonitrile in water containing 0.001M PIC B-8 as the mobile phase, linear calibration curves are obtained in the range from 1 to 5 mg/L of PYR and OMT. Sulfamonomethoxine, sulfadimethoxine, sulfaquinoxaline, trimethoprim, amprolium, clopidol, and nicarbazin do not interfere with the detection of PYR or OMT. The recoveries of PYR from spiked feed at 1 and 5 mg/Kg are 73.0% and 72.0%, respectively, and those of OMT from spiked feed at 3 and 7 mg/Kg are 50.3% and 53.6%, respectively. PMID:12137205

  10. A high-performance liquid chromatographic-atmospheric pressure chemical ionization-tandem mass spectrometric method for determination of risperidone and 9-hydroxyrisperidone in human plasma.

    PubMed

    Moody, David E; Laycock, John D; Huang, Wei; Foltz, Rodger L

    2004-09-01

    Risperidone, a benzisoxazole derivative, is an antipsychotic agent used for the treatment of schizophrenia. We developed a liquid chromatographic-atmospheric pressure chemical ionization-tandem mass spectrometric (LC-APCI-MS-MS) method with improved sensitivity, selectivity, and dynamic range for determination of risperidone and 9-hydroxyrisperidone in human plasma. A structural analogue of risperidone, RO68808 (5 ng/mL), is added as the internal standard to 1 mL of human plasma. Plasma is made basic, extracted with pentane/methylene chloride (3:1), the organic phase evaporated to dryness, and the residue is reconstituted in water with 0.1% formic acid/acetonitrile (20:1). For LC-MS-MS analysis, a Metachem Inertsel HPLC column (2.1 x 150 mm, 5-microm particle size) is connected to a Finnigan TSQ7000 tandem MS via the Finnigan API interface. Both electrospray (ESI) and APCI produced predominantly MH(+) ions for the two analytes and the internal standard. Ions detected by selected reaction monitoring correspond to the following transitions: m/z 411 to 191 for risperidone, m/z 427 to 207 for 9-hydroxyrisperidone, and m/z 421 to 201 for the internal standard. APCI provided a larger dynamic range (0.1 to 25 ng/mL) and better precision and accuracy than ESI. Intrarun accuracy and precision determined at 0.1, 0.25, 2.5, and 15 ng/mL were within 12% of target with %CVs not exceeding 10.9%. Interrun accuracy and precision determined at the same concentrations were within 9.6% of target with %CVs not exceeding 6.7%. Analytes were stable in plasma after 24 h at room temperature, 2 freeze-thaw cycles, and 490 days at -20 degrees C. PMID:15516302

  11. Development of a coupled-column liquid chromatographic-tandem mass spectrometric method for the direct determination of betamethasone in urine.

    PubMed

    Polettini, A; Marrubini Bouland, G; Montagna, M

    1998-08-25

    Different hyphenated liquid chromatographic (LC) and mass spectrometric (MS) techniques were investigated in order to set-up a method for the fast, direct analysis of betamethasone in hydrolysed and non-hydrolysed urine using large-volume sample injection. After the optimisation of the LC parameters using a traditional UV detector and of the thermospray and mass spectrometric parameters by flow injection, urine samples (0.5 ml) were submitted to analysis by either LC combined with tandem mass spectrometry (MS-MS), coupled-column LC (LC-LC) combined with single quadrupole MS, and LC-LC-MS-MS. Both the three-step configurations (LC-MS-MS and LC-LC-MS) did not provide satisfactory results: loss of sensitivity was noted in the case of LC-MS-MS (likely due to reduced efficiency in the ionisation of betamethasone in the thermospray owing to the presence of large amounts of matrix interference), while in the case of LC-LC-MS a high chemical noise resulting in insufficient selectivity of detection was observed. On the contrary, LC-LC-MS-MS analysis proved to meet the demand of high speed of analysis (sample throughput, 4.5 h(-1)), selectivity, and sensitivity (LOQ, 1 ng/ml; LOD, 0.2 ng/ml). Notwithstanding the complex analytical system adopted, the developed procedure was manageable and very robust, provided that at the beginning of each analytical session the performance of the system was controlled by checking the retention time of the analytes on the first analytical column with UV detection and by optimising vaporiser temperature of the thermospray by flow injection. PMID:9746249

  12. Novel characterization of Radix Angelicae Dahuricae before and after the sulfur-fumigation process by combining high performance liquid chromatographic fingerprint and multi-ingredients determination

    PubMed Central

    Liu, Xiao; Liu, Jingjing; Cai, Hao; Li, Songlin; Ma, Xiaoqing; Lou, Yajing; Qin, Kunming; Guan, Hongyue; Cai, Baochang

    2014-01-01

    Background: Harmful sulfur-fumigation processing method is abused during Radix Angelicae Dahuricae preparation. However, the analytical technique characterizing Radix Angelicae Dahuricae before and after the sulfur-fumigation process is absent. Materials and Methods: The high performance liquid chromatography (HPLC) technique was adopted to develop methods combining finger-print analysis and multi-ingredients simultaneous determination for quality evaluation of Radix Angelicae Dahuricae before and after the sulfur-fumigation process. The chromatographic fingerprint method was established for qualitative analysis coupled with statistical cluster analysis basing on Euclidean distance. Additionally, a determination method was developed for quantitative analysis, which was able to assay the concentrations of the major coumarins including imperatorin, isoimperatorin, xanthotoxin, xanthotoxol, isoimpinellin, oxypeucedanin, and bergapten in Radix Angelicae Dahuricae simultaneously. The separations of the two methods were both achieved on a Hypersil octadecylsilyl C18 column (250 mm × 4.6 mm, 5 μm) at 35°C under different strategic gradient elution programs. The detection wavelength was set at 254 nm all the time. Method validation data indicated that the methods were both reliable and applicable. They were then used to assay different Radix Angelicae Dahuricae samples collected from good agricultural practice (GAP) bases and local herbal markets. Results: The successful application demonstrated that the combination of HPLC fingerprint and simultaneous quantification of multi-ingredients offers an efficient approach for quality evaluation of Radix Angelicae Dahuricae before and after the sulfur-fumigation process. Conclusion: In order to discriminate Radix Angelicae Dahuricae before and after the sulfur-fumigation process, oxypeucedanin, and xanthotoxol were the most sensitive biomarkers and should be determined. PMID:25210323

  13. [Influences of ion-suppressors on retention behaviors of nine food additives in reversed-phase high performance liquid chromatographic separation].

    PubMed

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

    2011-10-01

    The influences of ion-suppressors on retention behaviors of nine food additives, i.e., acesulfame, saccharin, caffeine, aspartame, benzoic acid, sorbic acid, stevioside, dehydroacetic acid and neotame in reversed-phase high performance liquid chromatographic (RP-HPLC) separation were investigated. The organic modification effects of acids, i. e. , trifluoroacetic acid (TFA) and buffer salts, i. e. , TFA-ammonium acetate (AmAc) were studied emphatically. The relationships between retention factors of solutes and volume percentages of ion-suppressors in the mobile phase systems of acetonitrile-TFA aqueous solution and acetonitrile-TFA-AmAc aqueous solution were quantitatively established, separately. The separation of nine food additives was completed by a gradient elution with acetonitrile-TFA (0.01%, v/v)-AmAc (2. 5 mmol/L) aqueous solution as the mobile phases. An RP-HPLC method was established for the simultaneous determination of nine food additives in red wine. In the range of 10. 0 - 100. 0 mg/L, nine food additives showed good linearity with the correlation coefficients ( r2 ) larger than 0. 999 1. The limits of detection (LODs) were in the range of 0. 33 - 2. 36 mg/L and the limits of quantification (LOQs) were in the range of 1. 11 - 7. 80 mg/L. The spiked recoveries were between 87. 61% and 108. 4% with the relative standard deviations (RSDs) of 2. 2% -9. 4%. These results are of referential significance for the rapid establishment and accu- rate optimization of RP-HPLC separation for the simultaneous determination of food additives in other foods. PMID:22268355

  14. Analysis of anti-neoplastic drug in bacterial ghost matrix, w/o/w double nanoemulsion and w/o nanoemulsion by a validated 'green' liquid chromatographic method.

    PubMed

    Youssof, Abdullah M E; Salem-Bekhit, Mounir M; Shakeel, Faiyaz; Alanazi, Fars K; Haq, Nazrul

    2016-07-01

    The objective of the present investigation was to develop and validate a 'green' reversed phase high-performance liquid chromatography (RP-HPLC) method for rapid analysis of a cytotoxic drug 5-fluorouracil (5-FU) in bulk drug, marketed injection, water-in-oil (w/o) nanoemulsion, double water-in-oil-in-water (w/o/w) nanoemulsion and bacterial ghost (BG) matrix. The chromatography study was carried out at room temperature (25±1°C) using an HPLC system with the help of ultraviolet (UV)-visible detector. The chromatographic performance was achieved with a Nucleodur 150mm×4.6mm RP C8 column filled with 5µm filler as a static phase. The mobile phase consisted of ethyl acetate: methanol (7:3% v/v) which was delivered at a flow rate of 1.0mLmin(-1) and the drug was detected in UV mode at 254nm. The developed method was validated in terms of linearity (r(2)=0.998), accuracy (98.19-102.09%), precision (% RSD=0.58-1.17), robustness (% RSD=0.12-0.53) and sensitivity with satisfactory results. The efficiency of the method was demonstrated by the assay of the drug in marketed injection, w/o nanoemulsion, w/o/w nanoemulsion and BG with satisfactory results. The successful resolution of the drug along with its degradation products clearly established the stability-indicating nature of the proposed method. Overall, these results suggested that the proposed analytical method could be effectively applied to the routine analysis of 5-FU in bulk drug, various pharmaceutical dosage forms and BG. PMID:27154677

  15. A radiochemical high-performance liquid chromatographic method for the analysis of 2-fluoro-2-deoxy-D-glucose-derived metabolites in human chondrocytes.

    PubMed

    Fedders, G; Kock, R; Van de Leur, E; Greiling, H

    1993-05-15

    A high-performance liquid chromatography method with on-line radioactivity monitoring was developed for the measurement of 2-fluoro-2-deoxy-D-[U-14C]-glucose-derived metabolites in a cell culture system of human chondrocytes embedded in soft agarose. To optimize the chromatographic procedure, glucose-analogous substrates derived from 2-fluoro-2-deoxy-D-glucose by enzymatic synthesis in vitro were used. The synthesized metabolites could be separated by anion-exchange chromatography on a Partisil 10 SAX cartridge with a LiChrosorb RP 18-5 guard column eluted with a 35-min ion-strength/pH gradient performed from 15 mM NH4H2PO4, pH 3.8, to 0.75 M NH4H2PO4, pH 4.8, at a flow rate of 2 ml/min. Only by using an on-line radioactivity monitor instead of an off-line counting procedure was the resolution obtained sufficient for the determination of these intermediates. This method was applied to studying the metabolic pathway of 2-fluoro-2-deoxy-D-glucose in human chondrocytes. Due to the resistance of the chondrocytes embedded in soft agarose, the usual cell-lysing methods could not be used; therefore, an extraction procedure for acid-stable glucose metabolites, which may also be applied to other resistant cell lines or critical cell culture systems, was developed. With the procedure presented here, the existence of metabolites of 2-fluoro-2-deoxy-D-glucose resulting from enzymatic reactions following the hexokinase reaction could be proven.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8323040

  16. Disposable, enzymatically modified printed film carbon electrodes for use in the high-performance liquid chromatographic-electrochemical detection of glucose or hydrogen peroxide from immobilized enzyme reactors.

    PubMed

    Osborne, P G; Yamamoto, K

    1998-04-10

    Disposable screen-printed, film carbon electrodes (PFCE) were modified with cast-coated Osmium-polyvinylpyrridine-wired horse radish peroxidase gel polymer (Os-gel-HRP) to enable the detection of the reduction at 0 mV of hydrogen peroxide (H2O2) derived from a post-column immobilized enzyme reactor (IMER) containing acetylcholinesterase and choline oxidase. In another series of experiments PFCE were initially modified with cast-coated Os-gel-HRP and then treated with glucose oxidase in bovine serum albumin (BSA) and cross-linked with glutaraldehyde to form a bi-layer glucose-Os-gel-HRP PFCE. This bi-layer glucose-Os-gel-HRP PFCE generated a reduction current at 0 mV to H2O2 derived from the reaction of glucose oxidase and glucose in solution. These enzyme-modified PFCE were housed in a radial flow cell and coupled with cation-exchange liquid chromatographic methods to temporally separate substrates in solution for the determination of acetylcholine (ACh) and choline (Ch) in the first experimental series, or glucose in the second experimental series. These two disposable enzyme-modified PFCE exhibited linear current vs. substrate relations, were durable, being usable for approximately 40 determinations, and were sufficiently sensitive to be employed in biological sampling. Both assays utilized the same HPLC equipment. The limit of detection for ACh was 16 fmol/10 microl and that for glucose was 12 micromol/7.5 microl. ACh and Ch were measured from a microdialysate from the frontal cortex of a rat. Glucose in human urine was determined using the bi-layer glucose oxidase-Os-gel-HRP PFCE. PMID:9613927

  17. Preparation of monodispersed vinylpyridine-divinylbenzene porous copolymer resins and their application to high-performance liquid chromatographic separation of aromatic amines.

    PubMed

    Kitahara, Kei-Ichi; Okuya, Shuji; Yoshihama, Isao; Hanada, Takako; Nagashima, Kunio; Arai, Sadao

    2009-10-30

    For the separation of aromatic amines, two types of monodispersed porous polymer resins were prepared by the copolymerization of 2-vinylpyridine and 4-vinylpyridine with divinylbenzene in the presence of template silica gel particles (particle size 5 microm), followed by dissolution of the template silica gel in an alkaline solution. The transmission electron micrographs and the scanning electron micrograph revealed that these templated polymer resins have a spherical morphology with a good monodispersity and porous structure. Using these monodispersed polymer resins, the high-performance liquid chromatographic separation of aromatic amines in the mobile phases of pHs 2.0, 2.9, 4.1, 7.2 and 11.7 were carried out. The 2-vinylpyridine-divinylbenzene copolymer resins showed slightly stronger retentions for aromatic amines than the 4-vinylpyridine-divinylbenzene copolymer resins. Under acidic conditions (around pH 2.0), aniline and the toluidines showed no retention on these copolymer resins due to the repulsion between the cationic forms of these amines and pyridinium cations in the stationary phase, whereas less basic aromatic amines or non-basic acetanilide showed slight retentions. Above pH 4.1, the separation of aromatic amines with these polymer resins showed a typical reversed-phase mode separation. Therefore, the separation patterns of aromatic amines are effectively tunable by changing the pH value of the mobile phases. A good separation of eight aromatic amines was achieved at pH 2.9 using the 2-vinylpyridine-divinylbenzene copolymer resins. PMID:19442983

  18. Polarity-based fractionation in proteomics: hydrophilic interaction vs reversed-phase liquid chromatography.

    PubMed

    Jafari, M; Mirzaie, M; Khodabandeh, M; Rezadoost, H; Ghassempour, A; Aboul-Enein, H Y

    2016-07-01

    During recent decades, hydrophilic interaction liquid chromatography (HILIC) ahs been introduced to fractionate or purify especially polar solutes such as peptides and proteins while reversed-phase liquid chromatography (RPLC) is also a common strategy. RPLC is also a common dimension in multidimensional chromatography. In this study, the potential of HILIC vs RPLC chromatography was compared for proteome mapping of human peripheral blood mononuclear cell extract. In HILIC a silica-based stationary phase and for RPLC a C18 column were applied. Then separated proteins were eluted to an ion trap mass spectrometry system. Our results showed that the HILIC leads to more proteins being identified in comparison to RPLC. Among the total 181 identified proteins, 56 and 38 proteins were fractionated specifically by HILIC and RPLC, respectively. In order to demonstrate this, the physicochemical properties of identified proteins such as polarity and hydrophobicity were considered. This analysis indicated that polarity may play a major role in the HILIC separation of proteins vs RPLC. Using gene ontology enrichment analysis, it was also observed that differences in physicochemical properties conform to the cellular compartment and biological features. Finally, this study highlighted the potential of HILIC and the great orthogonality of RPLC in gel-free proteomic studies. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26555197

  19. Diagnosis of phase transitions in disordered fractional quantum Hall liquids using quantum entanglement

    NASA Astrophysics Data System (ADS)

    Liu, Zhao; Bhatt, R. N.

    The conventional method to study phase transitions from fractional quantum Hall (FQH) liquids to a localized phase induced by disorder has relied on the collapse of the mobility gap and Hall conductance. Here, we scrutinize this issue from the perspective of quantum entanglement. We consider electrons in the disordered lowest Landau level at Laughlin filling fractions ν = 1 / m with either Haldane's pseudopotentials or Coulomb interaction. We find that the derivative of the orbital-cut von-Neumann entropy with respect to the disorder strength has a sharp peak, which diverges with system size, providing a clear fingerprint of the transition from FQH liquids to a localized phase. Further, the fluctuation of the entropy with different cut boundaries is utilized to examine whether the ground states are localized in some region. We also investigate the level statistics of the entanglement spectrum, as well as the low-lying spectrum of the Hamiltonian to extract more information about the phase transition. Our method can be applied to study many-body localization in other topological systems. This work was supported by US Department of Energy, Office of Basic Energy Sciences, through Grant No. DE-SC0002140.

  20. Fractional distillation as a strategy for reducing the genotoxic potential of SRC-II coal liquids: a status report

    SciTech Connect

    Pelroy, R.A.; Wilson, B.W.

    1981-09-01

    This report presents results of studies on the effects of fractional distillation on the genotoxic potential of Solvent Refined Coal (SRC-II) liquids. SRC-II source materials and distilled liquids were provided by Pittsburg and Midway Coal Mining Co. Fractional distillations were conducted on products from the P-99 process development unit operating under conditions approximating those anticipated at the SRC-II demonstration facility. Distillation cuts were subjected to chemical fractionation, in vitro bioassay and initial chemical analysis. Findings are discussed as they relate to the temperature at which various distillate cuts were produced. This document is the first of two status reports scheduled for 1981 describing these studies.

  1. Sensitive determination of estrogens in environmental waters treated with polymeric ionic liquid-based stir cake sorptive extraction and liquid chromatographic analysis.

    PubMed

    Chen, Lei; Mei, Meng; Huang, Xiaojia; Yuan, Dongxing

    2016-05-15

    A simple, sensitive and environmentally friendly method using polymeric ionic liquid-based stir cake sorptive extraction followed by high performance liquid chromatography with diode array detection (HPLC/DAD) has been developed for efficient quantification of six selected estrogens in environmental waters. To extract trace estrogens effectively, a poly (1-ally-3-vinylimidazolium chloride-co-ethylene dimethacrylate) monolithic cake was prepared and used as the sorbent of stir cake sorptive extraction (SCSE). The effects of preparation conditions of sorbent and extraction parameters of SCSE for estrogens were investigated and optimized. Under optimal conditions, the developed method showed satisfactory analytical performance for targeted analytes. Low limits of detection (S/N=3) and quantification limits (S/N=10) were achieved within the range of 0.024-0.057µg/L and 0.08-0.19µg/L, respectively. Good linearity of method was obtained for analytes with the correlation coefficients (R(2)) above 0.99. At the same time, satisfactory method repeatability and reproducibility was achieved in terms of intra- and inter-day precisions, respectively. Finally, the established SCSE-HPLC/DAD method was successfully applied for the determination of estrogens in different environmental water samples. Recoveries obtained for the determination of estrogens in spiked samples ranged from 71.2% to 108%, with RSDs below 10% in all cases. PMID:26992499

  2. A fully automated effervescence-assisted switchable solvent-based liquid phase microextraction procedure: Liquid chromatographic determination of ofloxacin in human urine samples.

    PubMed

    Vakh, Christina; Pochivalov, Aleksei; Andruch, Vasil; Moskvin, Leonid; Bulatov, Andrey

    2016-02-11

    A novel fully automated effervescence-assisted switchable solvent-based liquid phase microextraction procedure has been suggested. In this extraction method, medium-chain saturated fatty acids were investigated as switchable hydrophilicity solvents. The conversion of fatty acid into hydrophilic form was carried out in the presence of sodium carbonate. The injection of sulfuric acid into the solution decreased the pH value of the solution, thus, microdroplets of the fatty acid were generated. Carbon dioxide bubbles were generated in-situ, and promoted the extraction process and final phase separation. The performance of the suggested approach was demonstrated by the determination of ofloxacin in human urine samples using high-performance liquid chromatography with fluorescence detection. This analytical task was used as a proof-of-concept example. Under the optimal conditions, the detector response of ofloxacin was linear in the concentration ranges of 3·10(-8)-3·10(-6) mol L(-1). The limit of detection, calculated from a blank test based on 3σ, was 1·10(-8) mol L(-1). The results demonstrated that the presented approach is highly cost-effective, simple, rapid and environmentally friendly. PMID:26803002

  3. Phosphorus, copper and zinc in solid and liquid fractions from full-scale and laboratory-separated pig slurry.

    PubMed

    Popovic, Olga; Hjorth, Maibritt; Jensen, Lars Stoumann

    2012-09-01

    Pig slurry separation is a slurry treatment technique that can reduce excess loads of P, Cu and Zn to the arable land. This study investigated the effects of different commercial and laboratory separation treatments for pig slurry on P, Cu and Zn distribution into solid and liquid fractions. Solid and liquid separation fractions were collected from two commercial separators installed on the farm. Five different separation treatments were performed (polymer flocculation and drainage; coagulation with iron sulphate addition and polymer flocculation and drainage; ozonation and centrifugation; centrifugation only; and natural sedimentation) on sow and suckling piglet raw slurry. Particle size fractionation was performed on raw slurry and all separation fractions by sequential wet sieving and P, Cu and Zn concentrations were then measured in the particle size classes. Dry matter and total P, Cu and Zn were separated with higher efficiency when chemical pretreatments with flocculants and coagulants were introduced before mechanical separation at both commercial and laboratory scale. When solid fractions are utilized as crop fertilizer (primarily as P fertilizer), the loads of Cu and Zn to the soils are not markedly different than the loads applied with raw slurry. When liquid fractions are used as crop fertilizer (primarily as N fertilizer), the loads of Cu and Zn are markedly lower than those supplied with raw slurry. The loads of Cu and Zn introduced to the soil were lowest on application of the liquid fraction produced by optimized separation treatments that included flocculation and coagulation. PMID:23240207

  4. Liquid chromatographic determination of water

    DOEpatents

    Fortier, N.E.; Fritz, J.S.

    1990-11-13

    A sensitive method for the determination of water in the presence of common interferences is presented. The detection system is based on the effect of water on the equilibrium which results from the reaction aryl aldehydes, such as cinnamaldehyde and methanol in the eluent to form cinnamaldehyde dimethylacetal, plus water. This equilibrium is shifted in a catalytic atmosphere of a hydrogen ion form past column reactor. The extent of the shift and the resulting change in absorbance are proportional to the amount of water present. 1 fig.

  5. Liquid chromatographic determination of water

    DOEpatents

    Fortier, Nancy E.; Fritz, James S.

    1990-11-13

    A sensitive method for the determination of water in the presence of common interferences is presented. The detection system is based on the effect of water on the equilibrium which results from the reaction aryl aldehydes, such as cinnamaldehyde and methanol in the eluent to form cinnamaldehyde dimethylacetal, plus water. This equilibrium is shifted in a catalytic atmosphere of a hydrogen ion form past column reactor. The extent of the shift and the resulting change in absorbance are proportional to the amount of water present.

  6. Mixed hemimicelles solid-phase extraction of cephalosporins in biological samples with ionic liquid-coated magnetic graphene oxide nanoparticles coupled with high-performance liquid chromatographic analysis.

    PubMed

    Wu, Jianrong; Zhao, Hongyan; Xiao, Deli; Chuong, Pham-Huy; He, Jia; He, Hua

    2016-07-01

    A novel mixed hemimicelles solid phase extraction based on magnetic graphene oxide (Fe3O4/GO) and ionic liquid (IL) was developed for the simultaneous extraction and determination of trace cephalosporins in spiked human urine. The high surface area and excellent adsorption capacity of the graphene oxide after modification with1-hexadecyl-3-methylmidazoliumbromide(C16mimBr) were utilized adequately in the solid phase extraction(SPE) process. A comprehensive study of the parameters affecting the extraction recovery, such as the zeta-potential of magnetic graphene oxide, amounts of magnetic graphene oxide and surfactant, pH of solution, ionic strength, extraction time, and desorption condition were optimized. A comparative study on the use of different surfacant-coated Fe3O4/GO NPs as sorbents was presented. Good linearity (R(2)>0.9987) for all calibration curves was obtained. The LODs were ranged between 0.6 and 1.9ng mL(-1) for the cephalosporins and the LOQs were 1.5 to 5.5, respectively. Satisfactory recoveries(84.3% to 101.7%)and low relative standard deviations from 1.7% to 6.3% in biological matrices were achieved. The mixed hemimicelles magnetic SPE (MSPE) method based on ILs and Fe3O4/GO NPs magnetic separation has ever been successfully used for pretreatment of complex biological samples. PMID:27266334

  7. High performance liquid chromatographic method for the determination of cetirizine and ambroxol in human plasma and urine--a boxcar approach.

    PubMed

    Dharuman, J; Vasudhevan, M; Ajithlal, T

    2011-09-01

    A column switching high performance liquid chromatographic method with estimable sensitivity and accuracy was developed for the determination of cetirizine and ambroxol in human plasma using nebivolol as the internal standard. Plasma samples were prepared by liquid-liquid extraction in methylene chloride and a mixture of diethylether (80:20, v/v). The extracted samples were injected into a multifunctional clean-up column Supelcosil LCABZ (50 mm × 4.6 mm, 5 μm particle size) using mobile phase 1 comprising acetonitrile-phosphate buffer (pH 3.5; 20 mM) (20:80, v/v). The eluate of cetirizine and ambroxol were separated to an analytical Kromasil C(8) micro bore column (50 mm × 0.3 mm, 5 μm particle size) via a column switching device. A Kromasil C(18) analytical column (250 mm × 2.1 mm, 5 μm particle size) was used as a separation column. Mobile phase 2 consisting acetonitrile-triethylamine (0.5%) in phosphate buffer (pH 3.5; 20mM) (55:45, v/v) was used for the compound elution. The eluents were detected at 230 nm with photodiode array detector. An aliquot of 150 μl of plasma sample was introduced into the pretreatment column via the auto sampler using mobile phase 1 at a flow rate of 0.5 ml/min, column switching valve being positioned at A. The pretreatment column retained cetirizine, ambroxol and nebivolol (IS) in the column leaving the residual proteins of plasma eluted in void volume and drained out. The switching valve was shifted to position B at 7.5 min. Cetirizine, ambroxol and IS were eluted from the pretreatment column between 7. 5 and 11.5 min and introduced to the concentration column. Finally, cetirizine, ambroxol and IS were introduced to the separation column by switching valve using mobile phase 2 at a flow rate of 0.4 ml/min. During the analysis the pretreatment column was washed for the next analysis and resume to the position A. The total run time was 25 min for a sample. The procedure was repeated for urine analysis also. The method was

  8. [A chromatographic and surface-activity analysis of the fractions of Rokopols, block copolymers of propylene oxide and ethylene oxide separated from the technical product].

    PubMed

    Zgoda, Marian Mikołaj; Nachajski, Michał Jakub

    2008-01-01

    A metod of refininig technical Rokopols, products of copolymerization of ethylene oxide and propylene oxide of 30p160, 30p27 and 30p10 type was developed. The course of the relation between R(f)(R(m)) and the number of oxyethylene segments n(TE) in the molecule of the homological series ofpolyethyleneglycols (PEG) was used to examine the content of n(TE) in the refined fractions of Rokopols. For the aqueous solutions of Rokopols weight-average molecular mass M(w) was calculated and the surface tension coefficient gamma25 was determined on the basis of the stalgmometric method. The value of the critical micellar concentration (cmc) and the thermodynamic potential for micelle formation (DeltaG(m)(0)), which facilitates the assessment of the solubilizing abilities of the investigated class of copolymers, were estimated. PMID:19137973

  9. High-performance liquid chromatographic-ultraviolet assay for the simultaneous quantitation of BMS-181101 and its putative hydroxy metabolites in rat and monkey plasma.

    PubMed

    Shah, V R; Srinivas, N R; Campbell, D A; Mantha, S; Duncan, G; Schuster, A; Whigan, D W; Shyu, W C

    1996-01-01

    A specific, accurate, precise, and reproducible High-performance liquid chromatographic-Ultraviolet (HPLC-UV) method was developed for the simultaneous quantitation of BMS-181101 (I), a new antidepressant, and its putative metabolites, 6'-hydroxy (II) and 7'-hydroxy (III) of BMS-181101 in rat and monkey plasma. The assay procedure involved solid-phase extraction of the three analytes and the internal standard (IS; BMY-42568) on 1 mL Bond Elut CN cartridge using an automated solid phase extraction controller (ASPEC) system. The final elution of the analytes was performed using 0.25% triethylamine in methanol. The eluate mixture was evaporated to dryness, the residue was reconstituted in the mobile phase and injected onto a Zorbax Phenyl column (4.6 x 250 mm; 5 microns) at a flow-rate of 1.2 mL/min. The mobile phase consisted of 20% acetonitrile, 10% methanol, 69% water and 1% 1.0 M ammonium phosphate and 1.0 M tetramethylammonium hydroxide mixture adjusted to pH 3 by phosphoric acid. An ultraviolet absorbance detector set at 287 nm was used to detect the analytes. The nominal retention times were 5, 8, 15, and 18 min for II, III, I, and IS, respectively. The standard curves for the three analytes were linear in the concentration range of 50-1000 ng/mL. The lower limit of quantitation was 50 ng/mL for each analyte. The analyses of quality control (QC) samples indicated that the nominal values could be predicted with an accuracy of (+/-) 10.5% for all three analytes in rat and monkey plasma. The precision values of the QC samples for all three analytes were within 12.7% RSD for rat and monkey plasma. All three analytes and the IS were stable in the autosampler for at least 38 h; freeze/thaw stability of the 3 analytes was established for three cycles. Stability of BMS-181101 was established for one month at -20 degrees C. The application of the assay to a pharmacokinetic study in monkey is described. PMID:8792865

  10. High-performance liquid chromatographic analysis of amphotericin B in plasma, blood, urine and tissues for pharmacokinetic and tissue distribution studies.

    PubMed

    Wang, L H; Smith, P C; Anderson, K L; Fielding, R M

    1992-09-01

    A sensitive and reproducible high-performance liquid chromatographic method was developed to assay ampherotericin B in plasma, blood, urine and various tissue samples. Amphotericin B was isolated from each sample matrix by solid-phase extraction (Bond-Elut). The eluate from Bond-Elut containing amphotericin B was injected onto a reversed-phase C18 column (Waters, mu Bondpak, 10 microns, 300 mm x 3.9 mm I.D.) with a mobile phase of 45% acetonitrile in 2.5 mM Na2EDTA at 1 ml/min. Detection of amphotericin B was by ultraviolet absorption at 382 nm. Blood and tissues were homogenized and extracted with methanol prior to Bond-Elut extraction. The extraction efficiencies of amphotericin B from plasma, blood and tissues were approximately 90, 70 and 75%, respectively. The sensitivity of the assay was less than or equal to 5 ng/ml for plasma, less than or equal to 25 ng/ml for blood, 2.5 ng/ml for urine and 50 ng/g for tissues. The linearity of the assay method was up to 2.5 micrograms/ml for plasma, 5 micrograms/ml for blood, 500 ng/ml for urine and 500 micrograms/g for tissues. The assay was reproducible with an intra-day coefficient of variation (C.V., n = 3) of less than 5% in general for plasma, blood and tissues. The inter-day C.V. of the assay was less than 5% for plasma (n = 5), less than 10% for blood (n = 4) and less than 5% for tissues (n = 3). The overall variability in the urine assay was generally less than 10%. This method has demonstrated significant improvement in the sensitivity and reproducibility in assaying amphotericin B in plasma and especially in blood, urine and tissues. We have employed this assay to compare the pharmacokinetic and tissue distribution profiles of amphotericin B in rats and dogs following administration of Fungizone and ABCD (amphotericin B-cholesteryl sulfate colloidal dispersion), a lipid-based dosage form. In addition, the assay method for plasma and urine samples can also be applied to pharmacokinetics studies of amphotericin B

  11. A high pH based reversed-phase high performance liquid chromatographic method for the analysis of aminoglycoside plazomicin and its impurities.

    PubMed

    Tan, Li; Wlasichuk, Kenneth B; Schmidt, Donald E; Campbell, Robert L; Hirtzer, Pam; Cheng, Lisa; Karr, Dane E

    2012-07-01

    A reversed-phase high performance liquid chromatographic (RP-HPLC) method has been developed for the aminoglycoside (AG) plazomicin (ACHN-490). This method employed a high pH mobile phase (pH>11) with a gradient of 0.25 M ammonium hydroxide in water and acetonitrile, an XBridge C(18) column and UV detection at 210 nm. Although the molar UV absorption of plazomicin is weak, the high pH conditions of this method allow for higher loadings, which compensates for the inherent low UV sensitivity. Under these high pH conditions, impurities and degradants were base line separated from plazomicin. The mobile phases used for this method allowed for on-line mass detection for the impurities and degradants. The RP-HPLC method has been validated in terms of specificity, linearity and range, accuracy, and precision. The analytical method met specificity requirements of a homogenous peak with no interferences from the blank or from the known impurities in plazomicin. The linearity of the method for the plazomicin impurity determination was excellent, with a coefficient of determination (r(2)) of 0.9993, over the freebase (FB) concentration range of 0.0025-3.0 mg/mL. The method is capable of detecting impurities down to 0.1% of the peak area of plazomicin. A single point standard at a concentration of 1.0 mg/mL FB was validated over the range of 50-150% for quantitation of the freebase content (the assay) in bulk drug substance. The mean recoveries of FB are in the range 98.6-102.0% with a mean RSD (relative standard deviation) <1.0%. The study also examined the method precision for purity, impurities and the assay with two instruments on two different days. The method showed adequate accuracy and precision for the intended use. This high pH method was successfully used to determine the impurity and measure the drug content in the final plazomicin drug substance. In addition, the method with an on-line mass spectrometry detector has been used to characterize the structures of the

  12. The Role of Oxygen Fugacity in Fractionating Parent-Daughter Pairs between Basaltic and Sulfidic Liquids

    NASA Astrophysics Data System (ADS)

    Mershon, R. B.; Jackson, C.; Fei, Y.; Elardo, S. M.; Bennett, N.

    2015-12-01

    Here we examine the effect of oxygen fugacity on trace element partitioning between basaltic and sulfidic liquids. We specifically focus on parent-daughter pairs (Sm-Nd, Re-Os, Lu-Hf, Hf-W, U-Pb, and Th-Pb), such that the isotopic effects associated with sulfide fractionation can be predicted. This work is motivated by recent experiments and observations that suggest Earth experienced massive sequestration of a sulfide liquid to its core during the accretion phase, possibly under extremely reduced conditions. Experiments were run in graphite capsules using a piston-cylinder apparatus (1500°C, 1GPa). Starting compositions comprised ~2/3 of a synthetic MORB and ~1/3 FeS by weight. Oxygen fugacity was varied by adding the Fe component of the MORB starting composition as either FeO or FeSi2. Trace elements were added either as solutions or metal powders. Run durations ranged between one and four hours. The recovered samples were polished using either water or ethanol for lubrication, and then carbon-coated prior to analysis. Major elements were analyzed using a combination of EDS and WDS techniques. Trace element analyses are currently underway. Experiments with iron added as FeSi2 have relatively lower concentrations of O in the sulfide, lower concentrations of Fe in the basalt, and higher concentrations of S in the basalt. These same experiments contained sub-micron CaS and MgS phases within the FeS phase. These observations are consistent with the achievement of very low oxygen fugacity for experiments with FeSi2 added compared to experiments with FeO added. Once trace element partition coefficients are determined, they will be coupled to radiogenic isotope evolution models associated with sulfide fractionation under varying redox conditions.

  13. Terminal Liquid Mass Fractions and Terminal Mean Droplet Sizes in He Free-Jet Expansions

    SciTech Connect

    Knuth, E. L.; Kornilov, O.; Toennies, J. P.

    2011-05-20

    The terminal liquid mass fraction in He free-jet expansions is deduced from time-of-flight measurements using conservation of energy. Both the present results and results from prior measurements are correlated using a scaling parameter which was used previously for correlating droplet size as a function of source conditions. Deduced values of the mass fraction range from 0.047 to 0.42. The terminal mean droplet size is determined using a novel technique based on a size-dependent attenuation of the beam droplets when impacted by electrons. The determined sizes are in agreement with sizes obtained previously by crossing the droplet beam with an atomic beam, confirming the suitability of the present technique, which is relatively simple in comparison with crossing the droplet beam with an atomic beam. Measured values of the terminal velocity of the droplets are compared with values calculated for a model in which real-fluid properties are used for the enthalpy in the source but conversion of heat of condensation into energy of directed motion is neglected. The deviations from perfect-gas behavior in free-jet expansions are shown to be due to real-fluid properties and condensation.

  14. Acoustic Monitor for Liquid-Solid Slurries Measurements at Low Weight Fractions

    SciTech Connect

    Tavlarides, Lawrence L.

    2005-06-01

    Our effort in this project is to develop an acoustic monitor for accurate, real-time characterization of the size and weight fractions of solids in slurries for process monitoring and to determine the optimal timing for slurry transfers. This capability will be valuable in the Savannah River Site accelerated clean-up program. Our scientific work during the first research period developed a theory, supported by experiments, to describe sound attenuation of solids in suspensions in the presence of bubbles, which permits us to determine the solid-liquid weight percent. Engineering developments during the second research period led to the design, construction, and demonstration, in our laboratories, of the Syracuse Acoustic Monitor (SAM) system that measures weight percent solids accurately in slurries of 0.5 to 8.0 weight percent on-line and in real-time. Also, we had shown the potential for these measurements in solid-gas-liquid slurries by removing the interference due to the presence of gas bubbles.

  15. Application of gamma densitometer for measurement of void fraction in liquid hydrogen moderator of HANARO cold neutron source

    NASA Astrophysics Data System (ADS)

    Kim, Myong-Seop; Choi, Jungwoon; Sun, Gwang-Min; Lee, Kye-Hong

    2009-06-01

    The void fraction in the liquid hydrogen used for the moderator of the HANARO cold neutron source (CNS) was measured by using a gamma densitometer technique. A mock-up of the HANARO CNS facility with an electric heating system as the heat source instead of radiations was constructed. The photon transmissions through the hydrogen moderator were simulated to search for an optimum experimental condition. From the simulation, it was confirmed that Am-241 was suitable for the measurement of the void fraction in the liquid hydrogen medium. A gamma densitometer using the Am-241 gamma-ray source was designed and installed at the mock-up of the CNS. The attenuation of 59.5 keV gamma-rays from the Am-241 through the hydrogen medium was measured by using an HPGe detector. The void fraction was determined using the amount of the gamma-ray attenuation. The void fractions in the hydrogen moderator were measured for stable thermo-siphon loops with several electric heat loads applied to the moderator cell of the CNS mock-up. The longitudinal distribution of the void fraction inside the moderator cell was also determined. The void fraction measured at a heat load of 720 W had values of 8-41% depending on the height from the bottom of the moderator cell. The overall void fraction was obtained by volume-weighted averaging of its longitudinal distribution. The void fraction at the nuclear heating power expected at the normal operation condition of the HANARO CNS facility was determined to be about 20%. The large uncertainty was expected in the void fraction determination by a gamma densitometer for the liquid hydrogen medium with the void fraction less than 10%. When the void fraction of the liquid hydrogen was near 20%, the uncertainty in the void fraction determination by using a gamma densitometer became relatively small, and it was regarded as an acceptable level. The measurements for the void fraction will be very useful for the design and operation of the HANARO CNS.

  16. Bioprospecting of microalgae: Proper extraction followed by high performance liquid chromatographic-high resolution mass spectrometric fingerprinting as key tools for successful metabolom characterization.

    PubMed

    Stranska-Zachariasova, Milena; Kastanek, Petr; Dzuman, Zbynek; Rubert, Josep; Godula, Michal; Hajslova, Jana

    2016-03-15

    Currently, the interest in microalgae as a source of biologically active components exploitable as supplementary ingredients to food/feed or in cosmetics continues to increase. Existing research mainly aims to focus on revealing and recovering the rare, cost competitive components of the algae metabolom. Because these components could be of very different physicochemical character, a universal approach for their isolation and characterization should be developed. This study demonstrates the systematic development of the extraction strategy that represents one of the key challenges in effective algae bioprospecting, which predefines their further industrial application. By using of Trachydiscus minutus as a model microalgae biomass, following procedures were tested and critically evaluated in order to develop the generic procedure for microalgae bioprospecting: (i) various ways of mechanical disintegration of algae cells enabling maximum extraction efficiency, (ii) the use of a wide range of extraction solvents/solvent mixtures suitable for optimal extraction yields of polar, medium-polar, and non-polar compounds, (iii) the use of consecutive extractions as a fractionation approach. Within the study, targeted screening of selected compounds representing broad range of polarities was realized by ultra-high performance liquid chromatography coupled with high resolution tandem mass spectrometric detection (UHPLC-HRMS/MS), to assess the effectiveness of undertaken isolation steps. As a result, simple and high-throughput extraction-fractionation strategy based on consecutive extraction with water-aqueous methanol-hexane/isopropanol was developed. Moreover, to demonstrate the potential of the UHPLC-HRMS/MS for the retrospective non-target screening and compounds identification, the collected mass spectra have been evaluated to characterize the pattern of extracted metabolites. Attention was focused on medium-/non-polar extracts and characterization of lipid species

  17. Validation of Ultraviolet-visible and High-performance Liquid Chromatographic Methods for the Determination of Sodium p-Aminosalicylate and m-Aminophenol in a New Pharmaceutical Formulation.

    PubMed

    Hergert, Lisandro Y; Ravetti, Soledad; Mazzieri, Maria R

    2016-01-01

    Sodium p-aminosalycilate is an orphan drug used in patients affected with Multidrug-resistant Tuberculosis. Two methods, high-performance liquid chromatographic and ultraviolet spectrophotometric for the quantitative determination of sodium p-aminosalycilate and its degradation product m-aminophenol in a new pharmaceutical formulation, powder for extemporaneous reconstitution, were developed in the present work. The parameters linearity, precision, accuracy, specificity, robustness, limit of detection, and limit of quantification were also studied. Chromatography was carried out by reverse-phase technique on an RP-18 column with a mobile phase composed of 50 mM monobasic/dibasic phosphate buffer and methanol (42.5:42.5:15 v/v/v) with 1.9 g of hidroxytetrabutylammonium ionic pare adjusted to pH 7.0 with orthophosphoric acid. The ultraviolet spectrophotometric method was performed at 254 nm and 280 nm for quantification of sodium p-aminosalycilate and m-aminophenol, respectively. The proposed methods are highly sensitive, precise, and accurate and can be used for the reliable quantification of sodium p-aminosalycilate in the new alternative formulation. High-performance liquid chromatographic approach demonstrated to be a stability-indicating method, therefore suitable for the investigation of the chemical stability of sodium p-aminosalycilate. PMID:27125056

  18. Multiobjective optimization strategy based on desirability functions used for the microemulsion liquid chromatographic separation and quantification of norfloxacin and tinidazole in plasma and formulations.

    PubMed

    Abou-Taleb, Noura Hemdan; El-Wasseef, Dalia Rashad; El-Sherbiny, Dina Tawfik; El-Ashry, Saadia Mohamed

    2015-03-01

    The aim of the present study was to optimize a microemulsion liquid chromatography method for the simultaneous determination of norfloxacin and tinidazole binary mixture using a chemometric protocol. Optimization experiments were conducted through a process of screening and optimization. A 2(7-4) fractional factorial design was used as screening design. While the location of optimum conditions was established by applying Derringer's desirability function. The optimal mobile phase composition was predicted to be: 3.5% w/v SDS, 10.03% v/v 1-propanol, 0.5% v/v 1-octanol, and 0.3% triethylamine in 0.02 M phosphoric acid at pH 6.5. The mobile phase was delivered isocratically at a flow rate of 1 mL/min with UV detection at 290 nm. Tinidazole and norfloxacin were eluted with retention times of 1.8 and 5.8 min, respectively. The calibration plots displayed good linear relationships in the concentration ranges of 0.5-50 and 0.75-75 μg/mL for norfloxacin and tinidazole, respectively. The method was successfully applied for determination of both drugs in pharmaceutical dosage forms and real human plasma. Where the accuracy was proved by the low values of % error and high values of recovery, also the relative standard deviation for the results did not exceed 1.5%, proving the precision of the method. PMID:25565679

  19. An eight-month climatology of marine stratocumulus cloud fraction, albedo, and integrated liquid water

    NASA Technical Reports Server (NTRS)

    Fairall, C. W.; Hare, J. E.; Snider, Jack B.

    1990-01-01

    As part of the FIRE/Extended Time Observations (ETO) program, extended time observations were made at San Nicolas Island (SNI) from March to October, 1987. Hourly averages of air temperature, relative humidity, wind speed and direction, solar irradiance, and downward longwave irradiance were recorded. The radiation sensors were standard Eppley pyranometers (shortwave) and pyrgeometers (longwave). The SNI data were processed in several ways to deduce properties of the stratocumulus covered marine boundary layer (MBL). For example, from the temperature and humidity the lifting condensation level, which is an estimate of the height of the cloud bottom, can be computed. A combination of longwave irradiance statistics can be used to estimate fractional cloud cover. An analysis technique used to estimate the integrated cloud liquid water content (W) and the cloud albedo from the measured solar irradiance is also described. In this approach, the cloud transmittance is computed by dividing the irradiance measured at some time by a clear sky value obtained at the same hour on a cloudless day. From the transmittance and the zenith angle, values of cloud albedo and W are computed using the radiative transfer parameterizations of Stephens (1978). These analysis algorithms were evaluated with 17 days of simultaneous and colocated mm-wave (20.6 and 31.65 GHz) radiometer measurements of W and lidar ceilometer measurements of cloud fraction and cloudbase height made during the FIRE IFO. The algorithms are then applied to the entire data set to produce a climatology of these cloud properties for the eight month period.

  20. An experimental design approach to optimization of the liquid chromatographic separation conditions for the determination of metformin and glibenclamide in pharmaceutical formulation.

    PubMed

    Demiralay, Ebru Çubuk

    2012-06-01

    An optimization methodology is introduced for investigating the retention behavior and the separation factor of metformin, gliclazide (I.S.) and glibenclamide. This investigation has been focused on studying the influence of pH value of the mobile phase, concentration of acetonitrile and column temperature, which affect a complete separation of the chromatographic peaks of these compounds. The significant factors were optimized using full factorial design. Retention factor and separation factor were chosen as dependent variable. Optimum RP-LC chromatographic conditions for the separation of metformin, glibenclamide and gliclazide were obtained using X Terra column (150 mm × 4.6 mm I.D., 5 µm). The results show that the percentage of acetonitrile are the most important to investigate and sspH of the mobile phase and column temperature do not significantly affect the experimental results. The procedure was validated for linearity, accuracy, precision and recovery. Quantitation was accomplished using internal standard method. PMID:24061246

  1. Improved high performance liquid chromatographic separation of anthocyanin compounds from grapes using a novel mixed-mode ion-exchange reversed-phase column.

    PubMed

    McCallum, Jason L; Yang, Raymond; Young, J Christopher; Strommer, Judith N; Tsao, Rong

    2007-04-27

    A novel mixed mode HPLC method using a column combining both ion-exchange and reversed-phase separation mechanisms has been developed to facilitate analysis of anthocyanins in grapes. Chromatographic performance and subsequent analysis of anthocyanidin diglucosides and acylated compounds are significantly improved using the new column, compared to those associated with conventional C18 reversed-phase methods. The mixed mode column produces a distinctive eluting pattern for the different anthocyanin subgroups, avoiding overlaps found with C18 columns. The enhanced chromatographic resolution provides nearly complete separation of 37 anthocyanin types, and permits detection of delphinidin 3-O-(6''-O-caffeoyl) beta-D-glucoside for the first time in extracts of skins from Concord grapes. PMID:17382950

  2. Liquid chromatographic-tandem mass spectrometric method for the simultaneous determination of alkylphenols polyethoxylates, alkylphenoxy carboxylates and alkylphenols in wastewater and surface-water.

    PubMed

    Ciofi, L; Ancillotti, C; Chiuminatto, U; Fibbi, D; Checchini, L; Orlandini, S; Del Bubba, M

    2014-10-01

    Four different pellicular stationary phases (i.e. octadecylsilane, octasilane, Phenyl-Hexyl and pentafluorophenyl) were investigated for the chromatographic resolution of alkylphenols (APs), alkylphenols polyethoxylates (APnEOs) and alkylphenoxy carboxylates (APECs) using mixtures of water and organic solvents (i.e. methanol, acetonitrile and tetrahydrofuran) as eluents, in order to obtain their determination by a single LC-MS/MS run. In fact, alkylphenols and alkylphenoxy carboxylates must be analysed in negative ion mode, whereas alkylphenols polyethoxylates undergo ionisation only in positive ion mode, and therefore, two distinct LC-MS/MS analysis are commonly adopted. The best resolution among the aforementioned target analytes was achieved on the pentafluorophenyl column, eluting with an acidified water-acetonitrile-tetrahydrofuran mixture and using the post column addition of an ammonia solution in methanol for the detection of positively ionisable compounds. Under these optimized chromatographic conditions the investigated compounds were determined via a single chromatographic run, with only one polarity switch, in 15min, achieving the following instrumental detection limits: 600pg for AP1EOs, 0.8-14pg for AP2EOs, 10.4-150pg for APs and 4.4-4.8pg for APECs. The chromatographic method was coupled with solid-phase extraction and clean-up procedures and successfully applied to the analysis of wastewater and surface water samples, highlighting mean concentration ranging from 6ng/L for 4-t-OP1EC to 1434ng/L for 4-NP1121EC, depending on the sample analysed. PMID:25171944

  3. Instantaneous Measurement of Local Concentration and Vapor Fraction in Liquid-Gas Mixtures by Laser-Induced Breakdown Spectroscopy

    NASA Astrophysics Data System (ADS)

    Kido, Akihiro; Hoshi, Kenji; Kusaka, Hiroto; Ogawa, Hideyuki; Miyamoto, Noboru

    Laser-induced breakdown spectroscopy (LIBS) with atomic emission excited with a focused high-energy ND: YAG laser was applied to quantify the concentration and the vapor fraction of liquid-gas mixtures. With LIBS it is possible to quantify local concentrations accurately even in liquid-gas mixtures as the ratio of the number of fuel-borne hydrogen atoms to nitrogen or oxygen atoms in the ambient gas. The ratio has a strong linear relation with the ratio of the peak emission intensities regardless of phase of the fuel. As the full width at half maximum (FWHM) of the emission peak from the fuel-borne hydrogen increases linearly with the liquid fraction due to the Doppler shift with micro-explosions, the FWHM yields the fuel vapor fraction. Simultaneous, high-resolution measurements of equivalence ratios and vapor fractions in an intermittent fuel spray in a pressurized atmosphere were obtained with this method. The results showed that the tip of the intermittent spray has a richer mixture with a lower vapor fraction.

  4. Membrane filtration of the liquid fraction from a solid-liquid separator for swine manure using a cationic polymer as flocculating agent.

    PubMed

    Masse, L; Mondor, M; Dubreuil, J

    2013-01-01

    The liquid fraction from a solid-liquid separator for swine manure, which used a cationic polymer to promote particle flocculation, was processed by one nanofiltration and two reverse osmosis spiral-wound membranes. Eight different liquid fraction batches (750 to 1750 L) were concentrated at volumetric concentration ratios (VCRs, initial to final volumes) ranging from 2.3 to 4.2. Membrane fouling intensity was highly variable, as water flux recovery after concentration cycles ranged from 13% to 88%. The most severe fouling was caused by a liquid fraction that had relatively low suspended solids (SS) (774 mg/L) and was concentrated at a low VCR of 2.6. Raw manure collected the same day also contained low SS, suggesting that fewer sites were available for polymer adsorption and thus more polymer remained in the liquid. However, because of the high opacity of the samples, residual polymer could not be detected in any feed or concentrate samples. Fouling was not totally irreversible as over 97% of membrane flux could be recovered by cleaning with acidic and alkaline solutions. Further tests with spiked liquid fractions indicated that fouling due to residual polymer in solution started to occur at a polymer concentration of 3 and 11 mg/L in initial and concentrated effluents, respectively. If a cationic polymer is used to pretreat manure, the amount of added polymer would have to be closely related to SS content as opposed to manure volume, in order to leave very little residual polymer in solution. PMID:23837317

  5. Fractionalization beyond Luttinger Liquid in the spectroscopy of Lithium Purple Bronze

    NASA Astrophysics Data System (ADS)

    Natalia, Lera; Jose, Alvarez

    We offer an interpretation for the departures of ARPES and STS spectroscopies experiments in quasi-one-dimensional Lithium Purple Bronze (LiPB) from single-band Luttinger Liquid (LL) theory. We base our calculation on a phenomenological description of the published data proposed in the original experiments and consider two bands crossing the Fermi level. We discuss the breakdown of the LL scaling relation η = α - 1 , the separation of the spinon edge and the holon peak, the phenomenological TL fit to the Energy Distribution Curves (EDC) and the survival of power-like density of states down to 4K. We consider non-critical fluctuations in one of the separated modes in which the electron fractionalize, and discuss under which conditions could be related with the upturn in the resistivity at 20-30K. We discuss the possibility of a gap in such separated mode and its role on the robust one-dimensional behavior. The connection with the proposed triplet superconductivity is at T = 1 . 4 K is also studied. We acknowledge financial support from MINECO FIS2012-37549-C05-03.

  6. Promoting anaerobic biogasification of corn stover through biological pretreatment by liquid fraction of digestate (LFD).

    PubMed

    Hu, Yun; Pang, Yunzhi; Yuan, Hairong; Zou, Dexun; Liu, Yanping; Zhu, Baoning; Chufo, Wachemo Akiber; Jaffar, Muhammad; Li, Xiujin

    2015-01-01

    A new biological pretreatment method by using liquid fraction of digestate (LFD) was advanced for promoting anaerobic biogasification efficiency of corn stover. 17.6% TS content and ambient temperature was appropriate for pretreatment. The results showed that C/N ratio decreased to about 30, while total lignin, cellulose, and hemicellulose (LCH) contents were reduced by 8.1-19.4% after pretreatment. 3-days pretreatment was considered to be optimal, resulting in 70.4% more biogas production, 66.3% more biomethane yield and 41.7% shorter technical digestion time compared with the untreated stover. The reductions on VS, cellulose, and hemicellulose were increased by 22.1-35.9%, 22.3-35.4%, and 19.8-27.2% for LFD-treated stovers. The promoted anaerobic biogasification efficiency was mainly attributed to the improved biodegradability due to the pre-decomposition role of the bacteria in LFD. The method proved to be an efficient and low cost approach for producing bioenergy from corn stover, meanwhile, reducing LFD discharge and minimizing its potential pollution. PMID:25459818

  7. Effects of various assumptions on the calculated liquid fraction in isentropic saturated equilibrium expansions

    NASA Technical Reports Server (NTRS)

    Bursik, J. W.; Hall, R. M.

    1980-01-01

    The saturated equilibrium expansion approximation for two phase flow often involves ideal-gas and latent-heat assumptions to simplify the solution procedure. This approach is well documented by Wegener and Mack and works best at low pressures where deviations from ideal-gas behavior are small. A thermodynamic expression for liquid mass fraction that is decoupled from the equations of fluid mechanics is used to compare the effects of the various assumptions on nitrogen-gas saturated equilibrium expansion flow starting at 8.81 atm, 2.99 atm, and 0.45 atm, which are conditions representative of transonic cryogenic wind tunnels. For the highest pressure case, the entire set of ideal-gas and latent-heat assumptions are shown to be in error by 62 percent for the values of heat capacity and latent heat. An approximation of the exact, real-gas expression is also developed using a constant, two phase isentropic expansion coefficient which results in an error of only 2 percent for the high pressure case.

  8. Microbial biodiversity of the liquid fraction of rumen content from lactating cows.

    PubMed

    Sandri, M; Manfrin, C; Pallavicini, A; Stefanon, B

    2014-04-01

    Host and dietary interactions with the rumen microbiome can affect the efficacy of supplements, and their effect on the composition of the bacterial population is still unknown. A 16S rRNA metagenomic approach and Next-Generation Sequencing (NGS) technology were used to investigate the bacterial microbiome composition in the liquid fraction of the rumen content collected via stomach tubing. To investigate biodiversity, samples were taken from three groups of four lactating dairy cows given a supplement of either 50 g of potato protein (Ctrl group), or 50 g of lyophilized Saccharomyces cerevisiae (LY group) or 50 g of dried S. cerevisiae (DY group) in a potato protein support. Rumen samples were collected after 15 days of dietary treatments and milk production was similar between the three groups. Taxonomic distribution analysis revealed a prevalence of the Firmicutes phylum in all cows (79.76%) and a significantly (P<0.05) higher presence of the genus Bacillus in the DY group. Volatile fatty-acid concentration was not significantly different between groups, possibly because of relatively high inter-animal variability or limited effect of the treatments or both, and the correlation analysis with bacterial taxa showed significant associations, in particular between many Firmicutes genera and butyrate. Limited differences were observed between dietary treatments, but the lack of microbiome data before yeast administration does not allow to draw firm conclusions on the effect of dietary treatments. PMID:24524278

  9. A New Void Fraction Measurement Method for Gas-Liquid Two-Phase Flow in Small Channels

    PubMed Central

    Li, Huajun; Ji, Haifeng; Huang, Zhiyao; Wang, Baoliang; Li, Haiqing; Wu, Guohua

    2016-01-01

    Based on a laser diode, a 12 × 6 photodiode array sensor, and machine learning techniques, a new void fraction measurement method for gas-liquid two-phase flow in small channels is proposed. To overcome the influence of flow pattern on the void fraction measurement, the flow pattern of the two-phase flow is firstly identified by Fisher Discriminant Analysis (FDA). Then, according to the identification result, a relevant void fraction measurement model which is developed by Support Vector Machine (SVM) is selected to implement the void fraction measurement. A void fraction measurement system for the two-phase flow is developed and experiments are carried out in four different small channels. Four typical flow patterns (including bubble flow, slug flow, stratified flow and annular flow) are investigated. The experimental results show that the development of the measurement system is successful. The proposed void fraction measurement method is effective and the void fraction measurement accuracy is satisfactory. Compared with the conventional laser measurement systems using standard laser sources, the developed measurement system has the advantages of low cost and simple structure. Compared with the conventional void fraction measurement methods, the proposed method overcomes the influence of flow pattern on the void fraction measurement. This work also provides a good example of using low-cost laser diode as a competent replacement of the expensive standard laser source and hence implementing the parameter measurement of gas-liquid two-phase flow. The research results can be a useful reference for other researchers’ works. PMID:26828488

  10. A New Void Fraction Measurement Method for Gas-Liquid Two-Phase Flow in Small Channels.

    PubMed

    Li, Huajun; Ji, Haifeng; Huang, Zhiyao; Wang, Baoliang; Li, Haiqing; Wu, Guohua

    2016-01-01

    Based on a laser diode, a 12 × 6 photodiode array sensor, and machine learning techniques, a new void fraction measurement method for gas-liquid two-phase flow in small channels is proposed. To overcome the influence of flow pattern on the void fraction measurement, the flow pattern of the two-phase flow is firstly identified by Fisher Discriminant Analysis (FDA). Then, according to the identification result, a relevant void fraction measurement model which is developed by Support Vector Machine (SVM) is selected to implement the void fraction measurement. A void fraction measurement system for the two-phase flow is developed and experiments are carried out in four different small channels. Four typical flow patterns (including bubble flow, slug flow, stratified flow and annular flow) are investigated. The experimental results show that the development of the measurement system is successful. The proposed void fraction measurement method is effective and the void fraction measurement accuracy is satisfactory. Compared with the conventional laser measurement systems using standard laser sources, the developed measurement system has the advantages of low cost and simple structure. Compared with the conventional void fraction measurement methods, the proposed method overcomes the influence of flow pattern on the void fraction measurement. This work also provides a good example of using low-cost laser diode as a competent replacement of the expensive standard laser source and hence implementing the parameter measurement of gas-liquid two-phase flow. The research results can be a useful reference for other researchers' works. PMID:26828488

  11. Derivatization and gas chromatographic-mass spectrometric detection of anabolic steroid residues isolated from edible muscle tissues.

    PubMed

    Daeseleire, E; De Guesquière, A; Van Peteghem, C

    1991-01-01

    A method was developed for the detection of anabolic steroid residues in edible muscle tissues. After enzymic digestion of the tissue and purification on disposable C18 solid-phase extraction columns, the extract was injected onto a C18 reversed-phase high-performance liquid chromatographic column. Three fractions or windows were collected, each containing specific analytes. After evaporation to dryness, the residues were subjected to a derivatization procedure which yielded suitable derivatives. After gas chromatographic-mass spectrometric analysis, both gas chromatographic retention data and mass spectral data were used for the detection and identification of nortestosterone, testosterone, estradiol, ethinylestradiol, trenbolone, methyltestosterone, chlormadinone acetate, medroxyprogesterone acetate and megestrol acetate. PMID:2026730

  12. Reversed-phase high-performance liquid chromatography of the stable electrophoretic fractions of soil humic acids

    NASA Astrophysics Data System (ADS)

    Trubetskoi, O. A.; Trubetskaya, O. E.

    2015-02-01

    Reversed-phase high-performance liquid chromatography (RP-HPLC) has been used for the hydrophobicity analysis of soil humic acids and their stable electrophoretic fractions A, B, and C + D preliminarily prepared by the combination of gel permeation chromatography on Sephadex with polyacrylamide gel electrophoresis. In two humic acid preparations of different genesis, the electrophoretic fraction A of the larger molecular size was the most hydrophobic (60-73% of the fraction was irreversibly adsorbed on a hydrophobic reversed-phase (RF) column C18), and the fraction C + D of the smallest molecular size was the most hydrophilic. The fraction B of medium size occupied an intermediate position (33-47% of the fraction was irreversibly adsorbed on the column). The use of RP-HPLC allowed for the first time detecting the hydrophobic electrophoretic fraction A of the largest molecular size mainly composed of aliphatic long-chained hydrocarbon, protein, and carbohydrate fragments in soil humic acids. Data on the degree of hydrophobicity and the earlier obtained physicochemical characteristics of stable electrophoretic fractions are discussed in terms of the supramolecular and macromolecular structure of soil humic acids.

  13. Electric Microdischarges in Liquids and Prospects of Their Use in Plasma Chemistry

    NASA Astrophysics Data System (ADS)

    Ganieva, G. R.; Ziganshin, D. I.; Aukhadeev, M. M.; Timerkaev, B. A.

    2014-05-01

    An original method of decomposition of heavy hydrocarbons into light fractions in the plasma of a microarc discharge initiated between electrodes submerged in a liquid is proposed. The characteristics of the microarc discharges between electrodes submerged in different liquids were investigated. A chromatographic analysis of the gases formed in this case has been performed.

  14. Total milk fat extraction and quantification of polar and neutral lipids of cow, goat, and ewe milk by using a pressurized liquid system and chromatographic techniques.

    PubMed

    Castro-Gómez, M P; Rodriguez-Alcalá, L M; Calvo, M V; Romero, J; Mendiola, J A; Ibañez, E; Fontecha, J

    2014-11-01

    Although milk polar lipids such as phospholipids and sphingolipids located in the milk fat globule membrane constitute 0.1 to 1% of the total milk fat, those lipid fractions are gaining increasing interest because of their potential beneficial effects on human health and technological properties. In this context, the accurate quantification of the milk polar lipids is crucial for comparison of different milk species, products, or dairy treatments. Although the official International Organization for Standardization-International Dairy Federation method for milk lipid extraction gives satisfactory results for neutral lipids, it has important disadvantages in terms of polar lipid losses. Other methods using mixtures of solvents such as chloroform:methanol are highly efficient for extracting polar lipids but are also associated with low sample throughput, long time, and large solvent consumption. As an alternative, we have optimized the milk fat extraction yield by using a pressurized liquid extraction (PLE) method at different temperatures and times in comparison with those traditional lipid extraction procedures using 2:1 chloroform:methanol as a mixture of solvents. Comparison of classical extraction methods with the developed PLE procedure were carried out using raw whole milk from different species (cows, ewes, and goats) and considering fat yield, fatty acid methyl ester composition, triacylglyceride species, cholesterol content, and lipid class compositions, with special attention to polar lipids such as phospholipids and sphingolipids. The developed PLE procedure was validated for milk fat extraction and the results show that this method performs a complete or close to complete extraction of all lipid classes and in less time than the official and Folch methods. In conclusion, the PLE method optimized in this study could be an alternative to carry out milk fat extraction as a routine method. PMID:25200790

  15. Simple method for the extraction and reversed-phase high-performance liquid chromatographic analysis of carotenoid pigments from red yeasts (Basidiomycota, Fungi).

    PubMed

    Weber, Roland W S; Anke, Heidrun; Davoli, Paolo

    2007-03-23

    A simple method for the extraction of carotenoid pigments from frozen wet cells of red yeasts (Basidiomycota) and their analysis by reversed-phase HPLC using a C(18) column and a water/acetone solvent system is described. Typical red yeast carotenoids belonging to an oxidative series from the monocyclic gamma-carotene to 2-hydroxytorularhodin and from the bicyclic beta-carotene to astaxanthin were separated. Pigment identity was confirmed by LC-atmospheric pressure chemical ionisation (APCI) mass spectrometry using similar chromatographic conditions. PMID:17266973

  16. A liquid chromatographic method for analysis of all-rac-alpha-tocopheryl acetate and retinyl palmitate in medical food using matrix solid-phase dispersion in conjunction with a zero reference material as a method development tool.

    PubMed

    Chase, G W; Eitenmiller, R R; Long, A R

    1999-01-01

    A liquid chromatographic method is described for analysis of all-rac-alpha-tocopheryl acetate and retinyl palmitate in medical food. The vitamins are extracted from medical food without saponification by matrix solid-phase dispersion and chromatographed by normal-phase chromatography with fluorescence detection. Retinyl palmitate and all-rac-alpha-tocopheryl acetate are quantitated isocratically with a mobile phase of 0.125% (v/v) and 0.5% (v/v) isopropyl alcohol in hexane, respectively. Results compared favorably with label declarations on retail medical foods. Recoveries determined on an analyte-fortified zero reference material for a milk-based medical food averaged 98.3% (n = 25) for retinyl palmitate spikes and 95.7% (n = 25) for all-rac-alpha-tocopheryl acetate spikes. Five concentrations were examined for each analyte, and results were linear (r2 = 0.995 for retinyl palmitate and 0.9998 for all-rac-alpha-tocopheryl acetate) over the concentration range examined, with coefficients of variation in the range 0.81-4.22%. The method provides a rapid, specific, and easily controlled assay for analysis of retinyl palmitate and all-rac-alpha-tocopheryl acetate in fortified medical foods. PMID:10028678

  17. Optimization by experimental design and artificial neural networks of the ion-interaction reversed-phase liquid chromatographic separation of twenty cosmetic preservatives.

    PubMed

    Marengo, E; Gianotti, V; Angioi, S; Gennaro, M C

    2004-03-12

    Particular attention are recently receiving antimicrobial agents added as preservatives in hygiene and cosmetics commercial products, since some of them are suspected to be harmful to the human health. The preservatives used belong to different classes of chemical species and are generally used in their mixtures. Multi-component methods able to simultaneously determinate species with different chemical structure are therefore highly required in quality control analysis. This paper presents an ion interaction RP-HPLC method for the simultaneous separation of the 20 typical antimicrobial agents most used in cosmetics and hygiene products, that are: benzoic acid, salicylic acid, 4-hydroxybenzoic acid, methyl-, ethyl-, propyl-, butyl-, benzyl-benzoate, methyl-, ethyl-, propyl-, butyl-, benzyl-paraben, o-phenyl-phenol, 4-chloro-m-cresol, triclocarban, dehydroacetic acid, bronopol, sodium pyrithione and chlorhexidine. For the development of the method and the optimization of the chromatographic conditions, an experimental design was planned and models were built by the use of artificial neural network to correlate the retention time of each analyte to the variables and their interactions. The neuronal models developed showed good predictive ability and were used, by a grid search algorithm, to optimize the chromatographic conditions for the separation of the mixture. PMID:15032350

  18. Microminiature gas chromatographic column

    NASA Technical Reports Server (NTRS)

    Donaldson, R. W., Jr.

    1972-01-01

    Techniques commonly used for fabrication of integrated circuits are utilized to produce long capillary tubes for microminiature chromatographs. Method involves bonding of flat silicon plate to top of spirally grooved silicon chip to close groove and form capillary column.

  19. Application of optically pure amines as chiral auxiliaries to develop trichloro-s-triazine-based new chiral derivatizing reagents for reversed-phase high-performance liquid chromatographic enantioseparation of DL-selenomethionine.

    PubMed

    Bhushan, Ravi; Lal, Manohar

    2013-08-01

    (R)-(+)-naphthylethyl amine and (S)-(+)-1-benzyl-3-aminopyrrolidine were incorporated as chiral auxiliaries, by nucleophilic substitution of chlorine atoms, in cyanuric chloride (CC) or its 6-butoxy derivative. There were obtained four new chiral derivatizing reagents (CDRs) as two dichloro and two monochloro triazine reagents. The CDRs so obtained were characterized and their optical purity was ascertained. Diastereomers of dl-selenomethionine were synthesized under microwave irradiation for 60 or 90 s (at 80% power of 800 W). Reversed-phase high-performance liquid chromatographic separation of diastereomers was carried out on a C18 column using mixtures of acetonitrile with aqueous trifluoroacetic acid as mobile phase. The detection was made at 230 nm using a photodiode array detector. The separation behaviors in terms of retention times and resolutions were compared. The separation method was validated for limit of detection, linearity, accuracy, precision, and recovery. PMID:23529857

  20. High performance liquid chromatographic determination of ultra traces of two tricyclic antidepressant drugs imipramine and trimipramine in urine samples after their dispersive liquid-liquid microextraction coupled with response surface optimization.

    PubMed

    Shamsipur, Mojtaba; Mirmohammadi, Mehrosadat

    2014-11-01

    Dispersive liquid-liquid microextraction (DLLME) coupled with high performance liquid chromatography by ultraviolet detection (HPLC-UV) as a fast and inexpensive technique was applied to the determination of imipramine and trimipramine in urine samples. Response surface methodology (RSM) was used for multivariate optimization of the effects of seven different parameters influencing the extraction efficiency of the proposed method. Under optimized experimental conditions, the enrichment factors and extraction recoveries were between 161.7-186.7 and 97-112%, respectively. The linear range and limit of detection for both analytes found to be 5-100ng mL(-1) and 0.6ng mL(-1), respectively. The relative standard deviations for 5ng mL(-1) of the drugs in urine samples were in the range of 5.1-6.1 (n=5). The developed method was successfully applied to real urine sample analyses. PMID:25178259

  1. An assessment of Salmonella survival in pig manure and its separated solid and liquid fractions during storage.

    PubMed

    McCarthy, Gemma; Lawlor, Peadar G; Gutierrez, Montserrat; O'Sullivan, Laurie; Murphy, Anne; Zhan, Xinmin; Gardiner, Gillian E

    2015-01-01

    The objective of this study was to examine Salmonella survival in pig manure and its separated fractions during storage. Salmonella declined, but significant reductions were not observed in the manure and liquid until day 56, whereas counts in the solids were lower by day 7. The Salmonella inoculum initially impacted counts but not after days 28-56. By day 112 Salmonella was undetectable in the manure and liquid but was recovered from the solids. There was no clear dominance of particular serotypes and antibiotic resistance transfer was not found. Storage duration and pH impacted Salmonella counts in all samples, with duration having the greatest effect. Of the nutrients, nitrate had the greatest impact in the manure and, together with phosphate, it also affected counts in the liquid fraction. This study demonstrates that if pig manure or its separated fractions are stored under controlled conditions at 10.5°C for 84-112 days Salmonella is reduced or eliminated, irrespective of the initial load. PMID:25587783

  2. Pre-treatment of lignocellulosic biomass using ionic liquids: wheat straw fractionation.

    PubMed

    da Costa Lopes, André M; João, Karen G; Rubik, Djonatam F; Bogel-Łukasik, Ewa; Duarte, Luís C; Andreaus, Jürgen; Bogel-Łukasik, Rafał

    2013-08-01

    This work is devoted to study pre-treatment methodologies of wheat straw with 1-ethyl-3-methylimidazolium acetate ([emim][CH3COO]) and subsequent fractionation to cellulose, hemicellulose and lignin. The method developed and described here allows the separation into high purity carbohydrate and lignin fractions and permits an efficient IL recovery. A versatility of the established method was confirmed by the IL reuse. The fractionation of completely dissolved biomass led to cellulose-rich and hemicellulose-rich fractions. A high purity lignin was also achieved. To verify the potential further applicability of the obtained carbohydrate-rich fractions, and to evaluate the pre-treatment efficiency, the cellulose fraction resulting from the treatment with [emim][CH3COO] was subjected to enzymatic hydrolysis. Results showed a very high digestibility of the cellulose samples and confirmed a high glucose yield for the optimized pre-treatment methodology. PMID:23735803

  3. Chromatographic alignment by warping and dynamic programming as a pre-processing tool for PARAFAC modelling of liquid chromatography-mass spectrometry data.

    PubMed

    Bylund, Dan; Danielsson, Rolf; Malmquist, Gunnar; Markides, Karin E

    2002-07-01

    Solutes analysed with LC-MS are characterised by their retention times and mass spectra, and quantified by the intensities measured. This highly selective information can be extracted by multiway modelling. However, for full use and interpretability it is necessary that the assumptions made for the model are valid. For PARAFAC modelling, the assumption is a trilinear data structure. With LC-MS, several factors, e.g. non-linear detector response and ionisation suppression may introduce deviations from trilinearity. The single largest problem, however, is the retention time shifts not related to the true sample variations. In this paper, a time warping algorithm for alignment of LC-MS data in the chromatographic direction has been examined. Several refinements have been implemented and the features are demonstrated for both simulated and real data. With moderate time shifts present in the data, pre-processing with this algorithm yields approximately trilinear data for which reasonable models can be made. PMID:12184621

  4. Secondary metabolites isolation in natural products chemistry: comparison of two semipreparative chromatographic techniques (high pressure liquid chromatography and high performance thin-layer chromatography).

    PubMed

    Do, Thi Kieu Tiên; Hadji-Minaglou, Francis; Antoniotti, Sylvain; Fernandez, Xavier

    2014-01-17

    Chemical investigations on secondary metabolites in natural products chemistry require efficient isolation techniques for characterization purpose as well as for the evaluation of their biological properties. In the case of phytochemical studies, the performance of the techniques is critical (resolution and yield) since the products generally present a narrow range of polarity and physicochemical properties. Several techniques are currently available, but HPLC (preparative and semipreparative) is the most widely used. To compare the performance of semipreparative HPLC and HPTLC for the isolation of secondary metabolites in different types of extracts, we have chosen carvone from spearmint essential oil (Mentha spicata L.), resveratrol from Fallopia multiflora (Thunb.) Haraldson, and rosmarinic acid from rosemary (Rosmarinus officinalis L.) extracts. The comparison was based on the chromatographic separation, the purity and quantity of isolated compounds, the solvent consumption, the duration and the cost of the isolation operations. The results showed that semipreparative HPTLC can in some case offer some advantages over conventional semipreparative HPLC. PMID:24377738

  5. Fast chromatographic method for the determination of dyes in beverages by using high performance liquid chromatography--diode array detection data and second order algorithms.

    PubMed

    Culzoni, María J; Schenone, Agustina V; Llamas, Natalia E; Garrido, Mariano; Di Nezio, Maria S; Band, Beatriz S Fernández; Goicoechea, Héctor C

    2009-10-16

    A fast chromatographic methodology is presented for the analysis of three synthetic dyes in non-alcoholic beverages: amaranth (E123), sunset yellow FCF (E110) and tartrazine (E102). Seven soft drinks (purchased from a local supermarket) were homogenized, filtered and injected into the chromatographic system. Second order data were obtained by a rapid LC separation and DAD detection. A comparative study of the performance of two second order algorithms (MCR-ALS and U-PLS/RBL) applied to model the data, is presented. Interestingly, the data present time shift between different chromatograms and cannot be conveniently corrected to determine the above-mentioned dyes in beverage samples. This fact originates the lack of trilinearity that cannot be conveniently pre-processed and can hardly be modelled by using U-PLS/RBL algorithm. On the contrary, MCR-ALS has shown to be an excellent tool for modelling this kind of data allowing to reach acceptable figures of merit. Recovery values ranged between 97% and 105% when analyzing artificial and real samples were indicative of the good performance of the method. In contrast with the complete separation, which consumes 10 mL of methanol and 3 mL of 0.08 mol L(-1) ammonium acetate, the proposed fast chromatography method requires only 0.46 mL of methanol and 1.54 mL of 0.08 mol L(-1) ammonium acetate. Consequently, analysis time could be reduced up to 14.2% of the necessary time to perform the complete separation allowing saving both solvents and time, which are related to a reduction of both the costs per analysis and environmental impact. PMID:19748097

  6. Superconductivity from a confinement transition out of a fractionalized Fermi liquid with Z2 topological and Ising-nematic orders

    NASA Astrophysics Data System (ADS)

    Chatterjee, Shubhayu; Qi, Yang; Sachdev, Subir; Steinberg, Julia

    2016-07-01

    The Schwinger boson theory of the frustrated square lattice antiferromagnet yields a stable, gapped Z2 spin liquid ground state with time-reversal symmetry, incommensurate spin correlations, and long-range Ising-nematic order. We obtain an equivalent description of this state using fermionic spinons (the fermionic spinons can be considered to be bound states of the bosonic spinons and the visons). Upon doping, the Z2 spin liquid can lead to a fractionalized Fermi liquid (FL*) with small Fermi pockets of electronlike quasiparticles, while preserving the Z2 topological and Ising-nematic orders. We describe a Higgs transition out of this deconfined metallic state into a confining superconducting state which is almost always of the Fulde-Ferrell-Larkin-Ovchinnikov type, with spatial modulation of the superconducting order.

  7. Experimental determination of Fe isotope fractionation between liquid metal, silicate and sulfide at high pressures and temperatures

    NASA Astrophysics Data System (ADS)

    Williams, H. M.; Wood, B. J.; Halliday, A. N.

    2007-12-01

    There is evidence for significant equilibrium Fe isotope fractionation (≤0.26‰/amu) between metal and troilite (FeS) in iron meteorites (Williams et al., EPSL (250) 2006) and a smaller fractionation (<0.1‰/amu) between metal and olivine in pallasites (Zhu et al., EPSL (200) 2002; Weyer et al., EPSL (240) 2005). Theory suggests that differences in iron oxidation state and coordination between metal, silicate and FeS will result in stable isotope fractionation (Polyakov and Mineev, GCA (64) 2000; Schauble et al., GCA (65) 2001). However, it is not yet clear if the apparent observed fractionations can be extrapolated to the pressure and temperature conditions of planetary core formation. We have investigated Fe isotope fractionation between silicate melt and liquid Fe-S alloys and between liquid iron and basaltic melt at pressure and temperature conditions of 2-2.5GPa and 1920-2150K using piston-cylinder partitioning experiments from previous studies (Kilburn and Wood EPSL (152) 1997; Gessmann and Wood, EPSL (200) 2002; Wood et al., EPSL (in revision) 2007). Metal, sulfide and silicate fractions were separated from mounted and sectioned experimental charges using a computer-controlled micromill (New Wave-Merchantek). Sample dissolution, Fe purification and isotopic analysis followed established procedures (Williams et al., EPSL (235) 2005). In agreement with another preliminary high-pressure experimental study (Poitrasson and Roskosz, LPSC XXXVIII 2007) we find no appreciable fractionation between liquid iron metal and basaltic melt. However, there is a resolvable Fe isotope fractionation between silicate melt and Fe-S alloy which ranges from 0.12±0.04 to 0.15±0.04‰/amu for separate experiments (errors are propagated based on the 2 SD errors of replicate analyses). The Fe isotope compositions of coexisting phases from these experiments define a positive linear relationship with a slope that is, within error, equal to unity, implying isotopic equilibrium. No

  8. Determination of bioactivity of chemical fractions of liquid wastes using freshwater and saltwater algae and crustaceans

    SciTech Connect

    Walsh, G.E.; Garnas, R.L.

    1983-03-01

    Complex wastes from industrial and municipal outfalls were fractionated chemically and tested for toxicity with freshwater and saltwater algae and crustaceans. The organic fraction of each waste was subfractionated into acid-, base-, and neutral-extractable portions, and the inorganic fraction was subfractionated into its anion and cation components. All wastes affected growth of the algae Skeletonema costatum (saltwater) and Monoraphidium capricornutum (freshwater) or survival of Mysidopsis bahia (saltwater) and Daphnia magna (freshwater). Usually, bioactivity was limited to one or two subfractions. In some cases, algal growth was stimulated by a fraction or subfraction, whereas stimulation was not detected in whole waste. It is suggested that fractionation must be done in order to estimate the full potential impact of complex wastes on aquatic systems. The method can also be used to identify toxic factors before application of cost-effective control technology.

  9. Liquid level, void fraction, and superheated steam sensor for nuclear-reactor cores. [PWR; BWR

    DOEpatents

    Tokarz, R.D.

    1981-10-27

    This disclosure relates to an apparatus for monitoring the presence of coolant in liquid or mixed liquid and vapor, and superheated gaseous phases at one or more locations within an operating nuclear reactor core, such as pressurized water reactor or a boiling water reactor.

  10. Synthesis, fractionation, and thin film processing of nanoparticles using the tunable solvent properties of carbon dioxide gas expanded liquids

    NASA Astrophysics Data System (ADS)

    Anand, Madhu

    Nanoparticles have received significant attention because of their unusual characteristics including high surface area to volume ratios. Materials built from nanoparticles possess unique chemical, physical, mechanical and optical properties. Due to these properties, they hold potential in application areas such as catalysts, sensors, semiconductors and optics. At the same time, CO 2 in the form of supercritical fluid or CO2 gas-expanded liquid mixtures has gained significant attention in the area of processing nanostructures. This dissertation focuses on the synthesis and processing of nanoparticles using CO2 tunable solvent systems. Nanoparticle properties depend heavily on their size and, as such, the ability to finely control the size and uniformity of nanoparticles is of utmost importance. Solution based nanoparticle formation techniques are attractive due to their simplicity, but they often result in the synthesis of particles with a wide size range. To address this limitation, a post-synthesis technique has been developed in this dissertation to fractionate polydisperse nanoparticles ( s . = 30%) into monodisperse fractions ( s . = 8%) using tunable physicochemical properties of CO 2 expanded liquids, where CO2 is employed as an antisolvent. This work demonstrates that by controlling the addition of CO2 (pressurization) to an organic dispersion of nanoparticles, the ligand stabilized nanoparticles can be size selectively precipitated within a novel high pressure apparatus that confines the particle precipitation to a specified location on a surface. Unlike current techniques, this CO2 expanded liquid approach provides faster and more efficient particle size separation, reduction in organic solvent usage, and pressure tunable size selection in a single process. To improve our fundamental understanding and to further refine the size separation process, a detailed study has been performed to identify the key parameters enabling size separation of various

  11. Mutagenicity testing of high performance liquid chromatography fractions from wood stove emission samples using a modified Salmonella assay requiring smaller sample volumes

    SciTech Connect

    Alfheim, I.; Becher, G.; Hongslo, J.K.; Ramdahl, T.

    1984-01-01

    Organic extracts of emissions from wood combustion have been fractionated by high performance liquid chromatography (HPLC) into 25-28 fractions. Each fraction was tested for mutagenic activity in a modified Ames Salmonella/microsome bioassay requiring one-third of the test volumes needed for the usual test. Direct mutagenic activity was noted predominantly in the most polar fractions, whereas indirect mutagenic activity was associated with the fractions containing polycyclic aromatic hydrocarbons (PAH) and with polar fractions probably consisting of aza-arenes and aromatic amines.

  12. Mutagenicity testing of high performance liquid chromatography fractions from wood stove emission samples using a modified Salmonella assay requiring smaller sample volumes

    SciTech Connect

    Alfheim, I.; Becher, G.; Hongslo, J.K.; Ramdahl, T.

    1984-01-01

    Organic extracts of emissions from wood combustion have been fractionated by high performance liquid chromatography (HPLC) into 25-28 fractions. Each fraction was tested for mutagenic activity in a modified Ames Salmonella/microsome bioassay requiring one-third of the test volumes needed for the ususal test. Direct mutagenic activity was noted predominantly in the most polar fractions, whereas indirect mutagenic activity was associated with the fractions containing polycyclic aromatic hydrocarbons (PAH) and with polar fractions probably consisting of aza-arenes and aromatic amines.

  13. Extraction and Chromatographic Determination of Shikimic Acid in Chinese Conifer Needles with 1-Benzyl-3-methylimidazolium Bromide Ionic Liquid Aqueous Solutions

    PubMed Central

    Chen, Fengli; Hou, Kexin; Li, Shuangyang; Zu, Yuangang; Yang, Lei

    2014-01-01

    An ionic liquids-based ultrasound-assisted extraction (ILUAE) method was successfully developed for extracting shikimic acid from conifer needles. Eleven 1-alkyl-3-methylimidazolium ionic liquids with different cations and anions were investigated and 1-benzyl-3-methylimidazolium bromide solution was selected as the solvent. The conditions for ILUAE, including the ionic liquid concentration, ultrasound power, ultrasound time, and liquid-solid ratio, were optimized. The proposed method had good recovery (99.37%–100.11%) and reproducibility (RSD, n = 6; 3.6%). ILUAE was an efficient, rapid, and simple sample preparation technique that showed high reproducibility. Based on the results, a number of plant species, namely, Picea koraiensis, Picea meyeri, Pinus elliottii, and Pinus banksiana, were identified as among the best resources of shikimic acid. PMID:24782942

  14. Pig slurry acidification and separation techniques affect soil N and C turnover and N2O emissions from solid, liquid and biochar fractions.

    PubMed

    Gómez-Muñoz, B; Case, S D C; Jensen, L S

    2016-03-01

    The combined effects of pig slurry acidification, subsequent separation techniques and biochar production from the solid fraction on N mineralisation and N2O and CO2 emissions in soil were investigated in an incubation experiment. Acidification of pig slurry increased N availability from the separated solid fractions in soil, but did not affect N2O and CO2 emissions. However acidification reduced soil N and C turnover from the liquid fraction. The use of more advanced separation techniques (flocculation and drainage > decanting centrifuge > screw press) increased N mineralisation from acidified solid fractions, but also increased N2O and CO2 emissions in soil amended with the liquid fraction. Finally, the biochar production from the solid fraction of pig slurry resulted in a very recalcitrant material, which reduced N and C mineralisation in soil compared to the raw solid fractions. PMID:26716355

  15. Simultaneous determination of the content of isoquinoline alkaloids in Dicranostigma leptopodum (Maxim) Fedde and the effective fractionation of the alkaloids by high-performance liquid chromatography with diode array detection.

    PubMed

    Chen, Yali; Li, Min; Liu, Jianjun; Yan, Qian; Zhong, Mei; Liu, Junxi; Di, Duolong; Liu, Jinxia

    2015-01-01

    A simple and efficient method was developed for the simultaneous determination of eight isoquinoline alkaloids in methanol extracts of Dicranostigma leptopodum (Maxim) Fedde and the effective fractionation of the alkaloids of D. leptopodum by high-performance liquid chromatography with diode array detection. The chromatographic conditions were optimized on a SinoChrom ODS-BP column to obtain a good separation of the four types of alkaloid analytes, including two aporphines (isocorydine, corydine), two protopines (protopine and allocryptopine), a morphine (sinoacutine), and three quaternary protoberberine alkaloids (berberrubine, 5-hydroxycoptisine, and berberine). The separation of these alkaloids was significantly affected by the composition of the mobile phase, and particularly by its pH value. Acetonitrile (A) and 0.2% phosphoric acid solution adjusted to pH 6.32 with triethylamine (B) were selected as the mobile phase with a gradient elution. With this method, a new quaternary protoberberine alkaloid was isolated and the two structural isomers (isocorydine and corydine) were baseline separated. The appropriate harvest period for D. leptopodum was also recommended based on our analysis. The method for the effective fraction of the alkaloids of D. leptopodum was optimized under this method with regard to the varying significant pharmacological activities of the alkaloids. PMID:25330407

  16. Development and validation of a reversed-phase column liquid chromatographic method for the determination of five cephalosporins in pharmaceutical preparations.

    PubMed

    Elkady, Ehab F; Abbas, Samah S

    2011-01-01

    A new, simple, rapid, and precise RP-HPLC method has been developed and validated for the determination of five cephalosporins, namely, cefalexin, cefoperazone, ceftriaxone, ceftazidime, and cefepime. The method has been applied successfully for simultaneous determination of cefalexin in a binary mixture with sodium benzoate in a suspension, and cefoperazone in a binary mixture with sulbactam in vials. Chromatographic separation was achieved on a Waters microBondapak C18 column (250 x 4.6 mm id, 10 pm particle size) using the mobile phase monobasic potassium phosphate (50 mM, pH 4.6)-acetonitrile (80 + 20, v/v) with UV detection. A flow rate of 1 mL/min was applied. Linearity, accuracy, and precision were found to be acceptable over the concentration range of 30-300, 3-30, and 15-120 microg/mL for the studied cephalosporins, sodium benzoate, and sulbactam, respectively. The optimized method proved to be specific, robust, and accurate for QC of the cited drugs in their pharmaceutical preparations. PMID:22165008

  17. A new hydrophilic interaction liquid chromatographic (HILIC) procedure for the simultaneous determination of pseudoephedrine hydrochloride (PSH), diphenhydramine hydrochloride (DPH) and dextromethorphan hydrobromide (DXH) in cough-cold formulations.

    PubMed

    Ali, Mohammed Shahid; Ghori, Mohsin; Rafiuddin, Syed; Khatri, Aamer Roshanali

    2007-01-01

    A new HILIC method has been developed for the simultaneous determination of pseudoephedrine hydrochloride (PSH), diphenhydramine hydrochloride (DPH) and dextromethorphan hydrobromide (DXH) in cough-cold syrup. Mobile phase consists of methanol:water (containing 6.0 g of ammonium acetate and 10 mL of triethylamine per liter, pH adjusted to 5.2 with orthophosphoric acid), 95:5 (v/v). Column containing porous silica particles (Supelcosil LC-Si, 25 cm x 4.6 mm, 5 microm) is used as stationary phase. Detection is carried out using a variable wavelength UV-vis detector at 254 nm for PSH and DPH, and at 280 nm for DXH. Solutions are injected into the chromatograph under isocratic condition at constant flow rate of 1.2 mL/min. Linearity range and percent recoveries for PSH, DPH and DXH were 150-600, 62.5-250, 75-300 microg/mL and 100.7%, 100.1% and 100.8%, respectively. Method is stability indicating and excipients like saccharin sodium, sodium citrate, flavour and sodium benzoate did not interfere in the analysis. Compounds elute in order of increasing ionization degree caused by cation-exchange mechanism in a run time of less than 15 min. Mobile phase pH is manipulated to regulate ionization and ion-exchange interaction and thereby retention of compounds. PMID:16887317

  18. Potential of liquid-isoelectric-focusing protein fractionation to improve phosphoprotein characterization of Pseudomonas aeruginosa PA14.

    PubMed

    Ouidir, Tassadit; Jarnier, Frédérique; Cosette, Pascal; Jouenne, Thierry; Hardouin, Julie

    2014-10-01

    Protein phosphorylation on serine, threonine, and tyrosine is known to be involved in a wide variety of cellular processes and signal transduction in bacteria. Bacterial-proteome analysis is required to determine which proteins have been conditionally expressed and whether any post-translational modifications are present. One of the greatest challenges of proteome analysis is the fractionation of these complex protein mixtures to detect low-abundance phosphoproteins. Liquid-phase isoelectric focusing (IEF) is a promising analytical tool in proteomics, but as far as we are aware no work has studied the reproducibility of this approach. In this study, we investigated the phosphoproteome of Pseudomonas aeruginosa strain PA14. We first tested in-solution IEF protein fractionation, and then used this technique to fractionate the proteins in the complex mixture. Next, phosphopeptides were enriched with titanium dioxide and analyzed by high-resolution, high-accuracy liquid chromatography-mass spectrometry. With this approach, we succeeded in characterizing 73 unique phosphorylated peptides belonging to 63 proteins. Interestingly, we observed a higher percentage of modified tyrosine, revealing the importance of this phosphorylated residue in bacteria. PMID:25096199

  19. Chromatographic hydrogen isotope separation

    DOEpatents

    Aldridge, F.T.

    Intermetallic compounds with the CaCu/sub 5/ type of crystal structure, particularly LaNiCo/sub 4/ and CaNi/sub 5/, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation column. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale multi-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen cn produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  20. Chromatographic hydrogen isotope separation

    DOEpatents

    Aldridge, Frederick T.

    1981-01-01

    Intermetallic compounds with the CaCu.sub.5 type of crystal structure, particularly LaNiCo.sub.4 and CaNi.sub.5, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation colum. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale mutli-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen can produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  1. Development and Bioanalytical Validation of a Liquid Chromatographic-Tandem Mass Spectrometric (LC-MS/MS) Method for the Quantification of the CCR5 Antagonist Maraviroc in Human Plasma

    PubMed Central

    Emory, Joshua F.; Seserko, Lauren A.; Marzinke, Mark A.

    2014-01-01

    Background Maraviroc is a CCR5 antagonist that has been utilized as a viral entry inhibitor in the management of HIV-1. Current clinical trials are pursuing maraviroc drug efficacy in both oral and topical formulations. Therefore, in order to fully understand drug pharmacokinetics, a sensitive method is required to quantify plasma drug concentrations. Methods Maraviroc-spiked plasma was combined with acetonitrile containing an isotopically-labeled internal standard, and following protein precipitation, samples were evaporated to dryness and reconstituted for liquid chromatographic-tandem mass spectrometric (LC-MS/MS) analysis. Chromatographic separation was achieved on a Waters BEH C8, 50 × 2.1 mm UPLC column, with a 1.7 μm particle size and the eluent was analyzed using an API 4000 mass analyzer in selected reaction monitoring mode. The method was validated as per FDA Bioanalytical Method Validation guidelines. Results The analytical measuring range of the LC-MS/MS method is 0.5-1000 ng/ml. Calibration curves were generated using weighted 1/x2 quadratic regression. Inter-and intra-assay precision was ≤ 5.38% and ≤ 5.98%, respectively; inter-and intra-assay accuracy (%DEV) was ≤ 10.2% and ≤ 8.44%, respectively. Additional studies illustrated similar matrix effects between maraviroc and its internal standard, and that maraviroc is stable under a variety of conditions. Method comparison studies with a reference LC-MS/MS method show a slope of 0.948 with a Spearman coefficient of 0.98. Conclusions Based on the validation metrics, we have generated a sensitive and automated LC-MS/MS method for maraviroc quantification in human plasma. PMID:24561264

  2. A validated liquid chromatographic method for the determination of polycyclic aromatic hydrocarbons in honey after homogeneous liquid-liquid extraction using hydrophilic acetonitrile and sodium chloride as mass separating agent.

    PubMed

    Koltsakidou, Anastasia; Zacharis, Constantinos K; Fytianos, Konstantinos

    2015-01-16

    In the present report, a simple and cost-effective method for the determination of twelve US EPA priority polycyclic aromatic hydrocarbons (PAHs) in honey samples after salting-assisted liquid-liquid extraction and UHPLC with fluorescence detection is proposed. The sample treatment is based on the usage of hydrophilic acetonitrile as extraction solvent and its phase separation under high salinity conditions. Due to the high sugar content of the samples the phase separation is promoted effortlessly. Several parameters affecting the extraction efficiency and method sensitivity including the concentration of the honey samples, the type and volume of the extraction solvent, the type and quantity of the inorganic salt, extraction time and centrifugation time was systematically investigated. The method was validated in-house according to the Commission Decision 2002/657/EC guidelines. The limit of detection (LOD) of the method lay between 0.02 and 0.04ngmL(-1) (corresponding to 0.08 and 0.16ngg(-1)) which are close to the quality criteria established by European Regulation (EC) 836/2011 concerning the PAHs in foodstuffs. The mean analytical bias (expressed as relative recoveries) in all spiking levels was acceptable being in the range of 54-118% while the relative standard deviation (RSD) was lower than 19%. The proposed method has been satisfactorily applied for the analysis of the selected PAHs residues in various honey samples obtained from Greek region. PMID:25543304

  3. Vortex- and CO2 -gas-assisted liquid-liquid microextraction with salt addition for the high-performance liquid chromatographic determination of furanic compounds in concentrated juices and dried fruits.

    PubMed

    Abu-Bakar, Nur-Bahiyah; Makahleh, Ahmad; Saad, Bahruddin

    2016-03-01

    A novel microextraction method based on vortex- and CO2 -assisted liquid-liquid microextraction with salt addition for the isolation of furanic compounds (5-hydroxymethyl-2-furaldehyde, 5-methyl-2-furaldehyde, 2-furaldehyde, 3-furaldehyde, 2-furoic and 3-furoic acids) was developed. Purging the sample with CO2 was applied after vortexing to enhance the phase separation and mass transfer of the analytes. The optimum extraction conditions were: extraction solvent (volume), propyl acetate (125 μL); sample pH, 2.4; vortexing time, 45 s; salt concentration, 25% w/v and purging time, 5 min. The analytes were separated using an ODS Hypersil C18 column (250×4.6 mm i.d, 5 μm) under gradient flow. The proposed method showed good linearities (r(2) >0.999), low detection limits (0.08-1.9 μg/L) and good recoveries (80.7-122%). The validated method was successfully applied for the determination of the furanic compounds in concentrated juice (mango, date, orange, pomegranate, roselle, mangosteen and soursop) and dried fruit (prune, date and apricot paste) samples. PMID:26718308

  4. /sup 57/Co-soap assay for plasma total non-esterified fatty acids compared with a gas-liquid chromatographic method

    SciTech Connect

    Turnell, D.C.; Price, C.P.; France, M.M.

    1980-12-01

    A relatively rapid radiochemical assay for determining plasma non-esterified fatty acids is described. Results correlated well with those by gas-liquid chromatography. The between-batch CV for 1.12 mmol of non-esterified fatty acids per liter was 7%.

  5. Measurement of two-phase refrigerant liquid-vapor mass flow rate. Part 1: Venturi and void fraction meters

    SciTech Connect

    Abdul-Razzak, A.; Shoukri, M.; Chang, J.S.

    1995-12-31

    The use of a venturi meter for the measurement of refrigerant liquid-vapor mass flow rate in a horizontal pipe is presented. Various models that utilize the output of the venturi flowmeter and the measured void fraction and/or quality to calculate the two-phase mass flow rate were examined. It was found that the applicability of the various models is dependent on the quality range. When the quality is less than 50%, the use of the momentum density model provides the best accuracy. For higher qualities, the use of the homogeneous equilibrium model is recommended.

  6. Protecting Gas Chromatographic Syringes

    NASA Astrophysics Data System (ADS)

    Ruekberg, Ben

    1995-12-01

    This article describes the construction of a device which protects gas chromatographic syringes. The device lessens the likelihood of syringes rolling off tables and breaking. If the syringe is dropped, the glass barrel is less apt to be struck and shattered.

  7. DETERMINATION OF BIOACTIVITY OF CHEMICAL FRACTIONS OF LIQUID WASTES USING FRESHWATER AND SALTWATER ALGAE AND CRUSTACEANS

    EPA Science Inventory

    A method is described for analysis of complex industrial and municipal wastes. The method uses chemical fractionation and subfractionation combined with laboratory toxicity tests on marine and freshwater algae and crustaceans to determine toxicity of whole waste and to identify i...

  8. OPTIMIZED DETERMINATION OF TRACE JET FUEL VOLATILE ORGANIC COMPOUNDS IN HUMAN BLOOD USING IN-FIELD LIQUID-LIQUID EXTRACTION WITH SUBSEQUENT LABORATORY GAS CHROMATOGRAPHIC-MASS SPECTROMETRIC ANALYSIS AND ON-COLUMN LARGE VOLUME INJECTION

    EPA Science Inventory

    A practical and sensitive method to assess volatile organic compounds (VOCs) from JP-8 jet fuel in human whole blood was developed by modifying previously established liquid-liquid extraction procedures, optimizing extraction times, solvent volume, specific sample processing te...

  9. Validation of high-performance liquid chromatographic methods for analysis of sustained-release preparations containing nitroglycerin, isosorbide dinitrate, or pentaerythritol tetranitrate.

    PubMed

    Gelber, L; Papas, A N

    1983-02-01

    The assay of sustained-release tablets or capsules containing nitroglycerin, isosorbide dinitrate, or pentaerythritol tetranitrate by high-performance liquid chromatography is described. Acetonitrile was found to be the sample preparation solvent with the most general applicability to these products. Anisole was used as an internal standard for nitroglycerin and pentaerythritol tetranitrate, while 4-chloroacetanilide was used for isosorbide dinitrate. The method, which uses a C18 bonded-phase column, a methanol-water mobile phase, and 214-nm detection, was shown to be accurate, linear, and reproducible. PMID:6403692

  10. Entrained liquid fraction calculation in adiabatic disperse-annular flows at low rate in film

    NASA Astrophysics Data System (ADS)

    Yagov, V. V.; Minko, M. V.

    2016-04-01

    In this work, we continue our study [1] and extend further an approach to low reduced pressures. An approximate model of droplets entrainment from the laminar film surface and an equation for calculating entrainment intensity are proposed. To carry out direct verification of this equation using experimental data is extremely difficult because the integral effect—liquid flow rate in a film at a dynamic equilibrium between entrainment and deposition—is usually measured in the experiments. The balance between flows of droplets entrainment and deposition corresponds to the dynamic equilibrium because of turbulent diffusion. The transcendental equation, which was obtained on the basis of this balance, contains one unknown numerical factor and allows one to calculate the liquid rate. Comparing calculation results with the experimental data for the water-air and water-helium flows at low reduced pressures (less than 0.03) has shown their good agreement at the universal value of a numerical constant, if an additional dimensionless parameter, a fourth root of vaporliquid densities ratio, is introduced. The criterion that determines the boundary of using methods of this work and that of [1] in calculations and that reflects effect of pressure and state of film surface on distribution of the liquid in the annular flow is proposed; the numerical value of this criterion has been determined.

  11. Catalytic cracking of the top phase fraction of bio-oil into upgraded liquid oil

    NASA Astrophysics Data System (ADS)

    Sunarno, Rochmadi, Mulyono, Panut; Budiman, Arief

    2016-06-01

    The energy consumption is increasing, while oil reserves as a primary energy resource are decreasing, so that is the reason seeking alternative energy source is inevitable. Biomass especially oil palm empty fruit bunches (EFB) which is abundant in Indonesia can be processed into bio-oil by pyrolysis process. The potential for direct substitution of bio-oil for petroleum may be limited due to the high viscosity, high oxygen content, low heating value, and corrosiveness. Consequently, upgrading of the bio-oil before use is inevitable to give a wider variety of applications of its liquid product. Furthermore, upgrading process to improve the quality of bio-oil by reduction of oxygenates involves process such as catalytic cracking. The objective of this research is to study the effect of operation temperature on yield and composition of upgraded liquid oil and to determine physical properties. Bio-oil derived from EFB was upgraded through catalytic cracking using series tubular reactor under atmospheric pressure on a silica-alumina catalyst. Results show that increasing temperature from 450 to 600 °C, resulting in decreasing of upgraded liquid oil (ULO) yield, decreasing viscosity and density of ULO, but increasing in calorimetric value of ULO. The increasing temperature of cracking also will increase the concentration of gasoline and kerosene in ULO.

  12. Hydrocarbon Liquid Production via Catalytic Hydroprocessing of Phenolic Oils Fractionated from Fast Pyrolysis of Red Oak and Corn Stover

    SciTech Connect

    Elliott, Douglas C.; Wang, Huamin; Rover, Majorie; Whitmer, Lysle; Smith, Ryan; Brown, Robert C.

    2015-04-13

    Phenolic oils were produced from fast pyrolysis of two different biomass feedstocks, red oak and corn stover and evaluated in hydroprocessing tests for production of liquid hydrocarbon products. The phenolic oils were produced with a bio-oil fractionating process in combination with a simple water wash of the heavy ends from the fractionating process. Phenolic oils derived from the pyrolysis of red oak and corn stover were recovered with yields (wet biomass basis) of 28.7 wt% and 14.9 wt%, respectively, and 54.3% and 58.6% on a carbon basis. Both precious metal catalysts and sulfided base metal catalyst were evaluated for hydrotreating the phenolic oils, as an extrapolation from whole bio-oil hydrotreatment. They were effective in removing heteroatoms with carbon yields as high as 81% (unadjusted for the 90% carbon balance). There was nearly complete heteroatom removal with residual O of only 0.4% to 5%, while N and S were reduced to less than 0.05%. Use of the precious metal catalysts resulted in more saturated products less completely hydrotreated compared to the sulfided base metal catalyst, which was operated at higher temperature. The liquid product was 42-52% gasoline range molecules and about 43% diesel range molecules. Particulate matter in the phenolic oils complicated operation of the reactors, causing plugging in the fixed-beds especially for the corn stover phenolic oil. This difficulty contrasts with the catalyst bed fouling and plugging, which is typically seen with hydrotreatment of whole bio-oil. This problem was substantially alleviated by filtering the phenolic oils before hydrotreating. More thorough washing of the phenolic oils during their preparation from the heavy ends of bio-oil or on-line filtration of pyrolysis vapors to remove particulate matter before condensation of the bio-oil fractions is recommended.

  13. Hydrocarbon Liquid Production via Catalytic Hydroprocessing of Phenolic Oils Fractionated from Fast Pyrolysis of Red Oak and Corn Stover

    DOE PAGESBeta

    Elliott, Douglas C.; Wang, Huamin; Rover, Majorie; Whitmer, Lysle; Smith, Ryan; Brown, Robert C.

    2015-04-13

    Phenolic oils were produced from fast pyrolysis of two different biomass feedstocks, red oak and corn stover and evaluated in hydroprocessing tests for production of liquid hydrocarbon products. The phenolic oils were produced with a bio-oil fractionating process in combination with a simple water wash of the heavy ends from the fractionating process. Phenolic oils derived from the pyrolysis of red oak and corn stover were recovered with yields (wet biomass basis) of 28.7 wt% and 14.9 wt%, respectively, and 54.3% and 58.6% on a carbon basis. Both precious metal catalysts and sulfided base metal catalyst were evaluated for hydrotreatingmore » the phenolic oils, as an extrapolation from whole bio-oil hydrotreatment. They were effective in removing heteroatoms with carbon yields as high as 81% (unadjusted for the 90% carbon balance). There was nearly complete heteroatom removal with residual O of only 0.4% to 5%, while N and S were reduced to less than 0.05%. Use of the precious metal catalysts resulted in more saturated products less completely hydrotreated compared to the sulfided base metal catalyst, which was operated at higher temperature. The liquid product was 42-52% gasoline range molecules and about 43% diesel range molecules. Particulate matter in the phenolic oils complicated operation of the reactors, causing plugging in the fixed-beds especially for the corn stover phenolic oil. This difficulty contrasts with the catalyst bed fouling and plugging, which is typically seen with hydrotreatment of whole bio-oil. This problem was substantially alleviated by filtering the phenolic oils before hydrotreating. More thorough washing of the phenolic oils during their preparation from the heavy ends of bio-oil or on-line filtration of pyrolysis vapors to remove particulate matter before condensation of the bio-oil fractions is recommended.« less

  14. Mesophilic and thermophilic anaerobic digestion of the liquid fraction of pressed biowaste for high energy yields recovery.

    PubMed

    Micolucci, Federico; Gottardo, Marco; Cavinato, Cristina; Pavan, Paolo; Bolzonella, David

    2016-02-01

    Deep separate collection of the organic fraction of municipal solid waste generates streams with relatively low content of inert material and high biodegradability. This material can be conveniently treated to recovery both energy and material by means of simplified technologies like screw-press and extruder: in this study, the liquid fraction generated from pressed biowaste from kerbside and door-to-door collection was anaerobically digested in both mesophilic and thermophilic conditions while for the solid fraction composting is suggested. Continuous operation results obtained both in mesophilic and thermophilic conditions indicated that the anaerobic digestion of pressed biowaste was viable at all operating conditions tested, with the greatest specific gas production of 0.92m(3)/kgVSfed at an organic loading rate of 4.7kgVS/m(3)d in thermophilic conditions. Based on calculations the authors found that the expected energy recovery is highly positive. The contents of heavy metals and pathogens of fed substrate and effluent digestates were analyzed, and results showed low levels (below End-of-Waste 2014 criteria limits) for both the parameters thus indicating the good quality of digestate and its possible use for agronomic purposes. Therefore, both energy and material were effectively recovered. PMID:26427935

  15. The validation of an analytical method for sulfentrazone residue determination in soil using liquid chromatography and a comparison of chromatographic sensitivity to millet as a bioindicator species.

    PubMed

    de Oliveira, Marcelo Antonio; Pires, Fábio Ribeiro; Ferraço, Mariana; Belo, Alessandra Ferreira

    2014-01-01

    Commonly used herbicides, such as sulfentrazone, pose the risk of soil contamination due to their persistence, bioaccumulation and toxicity. Phytoremediation by green manure species has been tested using biomarkers, but analytical data are now required to confirm the extraction of sulfentrazone from soil. Thus, the present work was carried out to analyze sulfentrazone residues in soil based on liquid chromatography with a comparison of these values to the sensitivity of the bioindicator Pennisetum glaucum. The soil samples were obtained after cultivation of Crotalaria juncea and Canavalia ensiformis at four seeding densities and with three doses of sulfentrazone. The seedlings were collected into pots, at two different depths, after 75 days of phytoremediator sowing and then were used to determine the herbicide persistence in the soil. A bioassay with P. glaucum was carried out in the same pot. High-performance liquid chromatography (HPLC), using UV-diode array detection (HPLC/UV-DAD), was used to determine the herbicide residues. The HPLC determination was optimized and validated according to the parameters of precision, accuracy, linearity, limit of detection and quantification, robustness and specificity. The bioindicator P. glaucum was more sensitive to sulfentrazone than residue determination by HPLC. Changes in sulfentrazone concentration caused by green manure phytoremediation were accurately identified by the bioindicator. However, a true correlation between the size of the species and the analyte content was not identified. PMID:25072201

  16. Determination of the phytoalexin resveratrol (3,5,4'-trihydroxystilbene) in peanuts and pistachios by high-performance liquid chromatographic diode array (HPLC-DAD) and gas chromatography-mass spectrometry (GC-MS).

    PubMed

    Tokuşoglu, Ozlem; Unal, Mustafa Kemal; Yemiş, Fadim

    2005-06-15

    The phytoalexin resveratrol (3,5,4'-trihydroxystilbene) in edible peanut (Arachis hypogaea L.) and pistachio (Pistacia vera L.) varieties grown in Turkey was analyzed by high-performance liquid chromatographic diode array and gas chromatography-mass spectrometric detection. trans-Resveratrol in six peanut varieties, five pistachio varieties, and four market samples ranged between 0.03 and 1.92 microg/g. The Cerezlik 5025 peanut (1.92 +/- 0.01 microg/g) and Ohadi pistachio genotype (1.67 +/- 0.01 microg/g) had significantly higher trans-resveratrol contents. Peanuts contained 0.03-1.92 microg/g (av = 0.84 microg/g) of trans-resveratrol, whereas pistachio contained 0.09-1.67 microg/g (av = 1.15 microg/g). With exposure to UV light for 1 min, trans-resveratrol concentrations of samples ranged from 0.02 to 1.47 microg/g and those of cis-resveratrol from 0.008 to 0.32 microg/g. The occurrence of resveratrol in peanut and pistachio was confirmed by total ion chromatograms (TIC) of bis[trimethylsilyl]trifluoroacetamide derivatives of resveratrol isomers and comparison of the mass spectral fragmentation data with those of a resveratrol standard. Formation of the cis-isomer in pistachios was higher than in peanuts. PMID:15941348

  17. Gradient liquid chromatographic retention time prediction for suspect screening applications: A critical assessment of a generalised artificial neural network-based approach across 10 multi-residue reversed-phase analytical methods.

    PubMed

    Barron, Leon P; McEneff, Gillian L

    2016-01-15

    For the first time, the performance of a generalised artificial neural network (ANN) approach for the prediction of 2492 chromatographic retention times (tR) is presented for a total of 1117 chemically diverse compounds present in a range of complex matrices and across 10 gradient reversed-phase liquid chromatography-(high resolution) mass spectrometry methods. Probabilistic, generalised regression, radial basis function as well as 2- and 3-layer multilayer perceptron-type neural networks were investigated to determine the most robust and accurate model for this purpose. Multi-layer perceptrons most frequently yielded the best correlations in 8 out of 10 methods. Averaged correlations of predicted versus measured tR across all methods were R(2)=0.918, 0.924 and 0.898 for the training, verification and test sets respectively. Predictions of blind test compounds (n=8-84 cases) resulted in an average absolute accuracy of 1.02±0.54min for all methods. Within this variation, absolute accuracy was observed to marginally improve for shorter runtimes, but was found to be relatively consistent with respect to analyte retention ranges (~5%). Finally, optimised and replicated network dependency on molecular descriptor data is presented and critically discussed across all methods. Overall, ANNs were considered especially suitable for suspects screening applications and could potentially be utilised in bracketed-type analyses in combination with high resolution mass spectrometry. PMID:26592605

  18. Emergence of Fractional Statistics for Tracer Particles in a Laughlin Liquid.

    PubMed

    Lundholm, Douglas; Rougerie, Nicolas

    2016-04-29

    We consider a thought experiment where two distinct species of 2D particles in a perpendicular magnetic field interact via repulsive potentials. If the magnetic field and the interactions are strong enough, one type of particles forms a Laughlin state and the other type couples to Laughlin quasiholes. We show that, in this situation, the motion of the second type of particles is described by an effective Hamiltonian, corresponding to the magnetic gauge picture for noninteracting anyons. The argument is in accord with, but distinct from, the Berry phase calculation of Arovas, Schrieffer, and Wilczek. It suggests possibilities to observe the influence of effective anyon statistics in fractional quantum Hall systems. PMID:27176506

  19. Emergence of Fractional Statistics for Tracer Particles in a Laughlin Liquid

    NASA Astrophysics Data System (ADS)

    Lundholm, Douglas; Rougerie, Nicolas

    2016-04-01

    We consider a thought experiment where two distinct species of 2D particles in a perpendicular magnetic field interact via repulsive potentials. If the magnetic field and the interactions are strong enough, one type of particles forms a Laughlin state and the other type couples to Laughlin quasiholes. We show that, in this situation, the motion of the second type of particles is described by an effective Hamiltonian, corresponding to the magnetic gauge picture for noninteracting anyons. The argument is in accord with, but distinct from, the Berry phase calculation of Arovas, Schrieffer, and Wilczek. It suggests possibilities to observe the influence of effective anyon statistics in fractional quantum Hall systems.

  20. Liquid chromatographic determination of 4,4'-dinitrocarbanilide, the active component of the infertility agent nicarbazin, in chicken, duck, goose, and snake eggs.

    PubMed

    Primus, Thomas M; Kohler, Dennis J; Goodall, Margaret A; Yoder, Christi; Mathies, Thomas; Miller, Lowell; Johnston, John J; Vercauteren, Kurt

    2003-01-01

    4,4'-Dinitrocarbanilide (DNC) was extracted from chicken, duck, goose, and snake eggs and isolated by reversed-phase liquid chromatography. DNC was detected by ultraviolet absorbance at 347 nm and quantitated by comparison with a calibration standard. Recoveries of DNC from fortified control chicken, duck, goose, and snake egg samples were determined for DNC levels of 0.16, 10, and 16 microg/g. The mean recoveries from chicken, duck, goose, and snake eggs were 92 +/- 4, 88 +/- 9, 87 +/- 7, and 95 +/- 6%, respectively. The method limits of detection for DNC in chicken, duck, goose, and snake eggs ranged from 0.015 to 0.035 microg/g. The reported method is much simpler than and equally efficient as previous methods developed for the determination of DNC residues in egg contents. PMID:14979695

  1. High-performance liquid chromatographic-electrospray ionization mass spectrometric analyses for the integration of natural products with modern high-throughput screening.

    PubMed

    Strege, M A

    1999-04-01

    Within the pharmaceutical industry, significant resources have been applied to the identification of new drug compound leads through the use of high-throughput screening (HTS). To meet the demand for rapid analytical characterization of biologically active samples identified by HTS, the technique of high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS) has been utilized, and the application of this technique specifically for the integration of natural product sample mixtures into modern HTS is reviewed. The high resolution provided by reversed-phase HPLC coupled with the gentle and relatively universal ionization facilitated by the electrospray process has had significant impact upon a variety of procedures associated with the HTS of natural products, including extract sample diversity evaluation, dereplication, structure elucidation, preparative isolation, and affinity-based biological activity evaluation. PMID:10226878

  2. A rapid high-performance liquid-chromatographic method for simultaneously determining the concentrations of TFM and Bayer 73 in water during lampricide treatments

    USGS Publications Warehouse

    Dawson, V.K.

    1982-01-01

    The high-performance liquid-chromatography (HPLC) procedure requires only minutes per sample, is specific, and is relatively sensitive (limit of detection 18 disposable cartridge. The cartridge adsorbs and retains both the lampricides and the internal standard. The quantitative elution of the three chemicals from the cartridge with a small volume of methanol effectively concentrates the sample and provides sample cleanup. The methanol extract is then analyzed directly by HPLC on an MCH 10 reverse phase column by using a methanol:0.01 mol/L acetate buffer (87:13, v:v) as the mobile phase at 2 mL/min and detected by ultraviolet spectrophotometry at 330 (or 254) nm. A microprocessor data system further facilitates the procedure by quantifying off-scale peaks and yielding results directly in units of concentration (mg/L).

  3. (S)-Naproxen as a platform to develop chiral derivatizing reagent for reversed-phase high-performance liquid chromatographic enantioseparation of analytes having a carbonyl functional group.

    PubMed

    Bhushan, Ravi; Lal, Manohar

    2012-12-01

    (S)-Naproxen was used to synthesize a chiral reagent, (S)-2-(6-methoxynaphthalen-2-yl)propanehydrazide, by itsreaction with hydrazine hydrate in the presence of dicyclohexylcarbodiimide as coupling agent. The reagent was characterized and its chiral purity was established. It was used as a chiral derivatizing reagent for the synthesis of hydrazone diastereomers, under microwave irradiation, of certain chiral aldehydes and ketones. The respective diastereomers were separated by reversed-phase high-performance liquid chromatography using a binary solvent combination containing trifluoroacetic acid. The diastereomers were detected at 231 nm. The method was validated for accuracy, precision, and limit of detection (LOD). For a series of hydrazones the LOD was found to be in the range 1.62-1.65 pmol/mL. PMID:22473802

  4. A Novel High Performance Liquid Chromatographic Method for Determination of Nystatin in Pharmaceutical Formulations by Box–Behnken Statistical Experiment Design

    PubMed Central

    Shokraneh, Farnaz; Asgharian, Ramin; Abdollahpour, Assem; Ramin, Mehdi; Montaseri, Ali; Mahboubi, Arash

    2015-01-01

    In this study a novel High Performance Liquid Chromatography for the assay of nystatin in oral and vaginal tablets were optimized and validated using Box–Behnken experimental design. The method was performed in the isocratic mode on a RP-18 column (30 °C) using a mobile phase consisting of ammonium acetate 0.05 M buffer/ Methanol mixture (30:70) and a flow-rate of 1.0 mL/min. The specificity, linearity, precision, accuracy, LOD and LOQ of the method were validated. The method was linear over the range of 5–500 µg/mL with an acceptable correlation coefficient (r2 = 0.9996). The method’s limit of detection (LOD) and quantification (LOQ) were 0.01 and 0.025 µg/mL respectively. The results indicate that this validated method can be used as an alternative method for assay of nystatin. PMID:26185504

  5. Improved method for the on-line metal chelate affinity chromatography-high-performance liquid chromatographic determination of tetracycline antibiotics in animal products.

    PubMed

    Cooper, A D; Stubbings, G W; Kelly, M; Tarbin, J A; Farrington, W H; Shearer, G

    1998-07-01

    An improved on-line metal chelate affinity chromatography-high-performance liquid chromatography (MCAC-HPLC) method for the determination of tetracycline antibiotics in animal tissues and egg has been developed. Extraction was carried out with ethyl acetate. The extract was then evaporated to dryness and reconstituted in methanol prior to on-line MCAC clean-up and HPLC-UV determination. Recoveries of tetracycline, oxytetracycline, demeclocycline and chlortetracycline in the range 42% to 101% were obtained from egg, poultry, fish and venison tissues spiked at 25 micrograms kg-1. Limits of detection less than 10 microgram kg-1 were estimated for all four analytes. This method has higher throughput, higher recovery and lower limits of detection than a previously reported on-line MCAC-HPLC method which involved aqueous extraction and solid-phase extraction clean-up. PMID:9691328

  6. Comparison of phenyl-type columns in the development of a fast liquid chromatographic system for eighteen opiates commonly found in forensic toxicology.

    PubMed

    Dams, R; Lambert, W E; Clauwaert, K M; De Leenheer, A P

    2000-10-27

    We report a precise and reliable method for the detection of 18 of the most commonly found opiates on the Belgian legal and illicit market, by ion-exchange, reversed-phase high-performance liquid chromatography, using a conventional phenyl-type analytical column (150x4.6 mm I.D., particle size 5 microm) and diode-array detection. We also describe a performance (efficiency and sensitivity) comparison of this column to a recently developed "high-speed" column (53x7.0 mm I.D., particle size 3 microm) packed with the same stationary phase, and used under slightly adjusted flow and gradient conditions. The final method, using the "high-speed" column, showed a significant reduction (55%) in analysis time without loss of resolution and sensitivity. PMID:11093666

  7. Reversed-phase liquid chromatographic purification and isolation of a radio-iodinated selective probe for mu opioid receptors in the brain.

    PubMed

    Miller, M M; Gould, B E; Joshi, D; Bennett, H P; James, S; Billiar, R B

    1992-02-01

    A Guard-PAK precolumn system was used for the reversed-phase liquid chromatography purification of a small, synthetic radiolabeled opioid peptide, FK 33-824 (D-Ala2, methyl-phe4, Met (O)ol5 enkephalin) (FK). This procedure involves trace enrichment of iodinated peptide onto the precolumn while iodination reagents are not retained. Radioactive contamination of high-performance liquid chromatography columns and injectors is thus avoided. Precolumn chromatography has sufficient resolving power to separate not only labeled from unlabeled peptide but also mono- from di-iodinated peptide. Purified 125I-labeled FK (estimated specific activity 85.9-153.7 Ci/mmol) showed high specific binding to mouse corpus striatum, neocortex, cingulate cortex, nucleus accumbens septi, diagonal band of Broca, nucleus medialis septi, area preopticus magnocellularis, and the nucleus of the caudate/putamen. Radioligand binding was inhibited by both antagonists (naloxone and naltrexone); and agonists D-Ala2, N-methyl-phe4, gly-ol5-enkephalin [DAGO]; FK; and beta-endorphin at all concentrations tested (1 x 10(-8) to 1 x 10(-4) M). Adrenocorticotropin hormone (ACTH) did not block ligand binding at any concentration tested. Distribution of mu opioid receptors was analyzed by light microscopic autoradiography. Sections incubated with 125I-labeled FK in the presence of agonists and antagonists demonstrated decreasing ligand binding with increasing doses of competitor. ACTH did not block ligand binding at any concentration tested. HPLC analyses of ligand which had been iodinated 1.5 half lives before the date of the experiment demonstrated a single peak similar to that of freshly iodinated ligand. Similar binding kinetics and autoradiographic labeling patterns were observed as compared to those obtained with freshly iodinated peptide.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1314320

  8. Chemical characterization and genotoxic potential related to boiling point for fractionally distilled SRC-I coal liquids

    SciTech Connect

    Wilson, B.W.; Pelroy, R.A.; Mahlum, D.D.

    1982-07-01

    This report summarizes selected research efforts oriented toward ameliorating the genotoxic potential of direct coal liquefaction materials through modification or optimization of process conditions. The studies described were conducted to evaluate the utility of optimized distillation for coal liquids from the SRC-I process. SRC-I process solvent was distilled into 50/sup 0/F-range boiling point (bp) cuts. Analysis of amino-PAH (APAH) showed that mutagenic APAHs containing 3 or more rings were found primarily in fractions boiling above 750/sup 0/F. Three microbial tester strains were used to screen for genetically active agents in the SRC-I distillate bp cuts. Reverse mutation with the Ames tester strain TA98 demonstrated that mutagens were concentrated in the bp cuts boiling above 700/sup 0/F. For this tester strain most of the genetic activity in these distillates was attributable to chemical fractions enriched in APAH having 3 or more rings. Mutagenicity data obtained with TA98 was in good agreement with sk in carcinogenesis results from the mouse-skin initiation/promotion (in vivo) test system. The strongest response in the forward mutation assay did not occur in the most carcinogenically active fractions. Results of initiation/promotion experiments used to measure the relative potency of bp cuts as initiators of mouse skin carcinogenesis again showed that fractions boiling above 750/sup 0/F. Compounds reaching their highest concentrations in the highest boiling and most carcinogenically active cut included known carcinogens such as benzo(a)pyrene and dimethyl benzanthracene. Thus, all biomedical test results indicate that consideration should be given to conducting distillation so as to minimize, in the distillate product, the concentrations of those biologically active compounds found in cuts boiling above 700/sup 0/C.

  9. Influence of a random field on particle fractionation and solidification in liquid-crystal colloid mixtures

    NASA Astrophysics Data System (ADS)

    Popa-Nita, V.; van der Schoot, P.; Kralj, S.

    2006-11-01

    The influence of a random-anisotropy (RA) type disorder on the phase separation of nematogen-colloid mixtures is studied theoretically by combining the phenomenological Landau-de Gennes, Carnahan-Starling, and hard-sphere crystal theories. We assume that the colloids enforce the RA disorder on the surrounding thermotropic liquid-crystal (LC) molecules. We adopt the Imry-Ma argument according to which the lower-temperature phase exhibits a domain-type pattern. The colloids impose a finite degree of orientational ordering even in the isotropic (paranematic) phase. In the ordered phase they give rise to a domain-type structure, resulting in the distorted nematic (speronematic) phase. The RA field opposes the phase separation tendency. With increasing disorder the difference between the paranematic and speronematic ordering decreases. Consequently there is a critical disorder, above which both phases become identical from the orientation point of view, but have different concentrations of colloids. We have also estimated another characteristic value of disorder above which the isotropic phase can exist only in a liquid state, the crystal phase being suppressed completely.

  10. Stability of arsenic peptides in plant extracts: off-line versus on-line parallel elemental and molecular mass spectrometric detection for liquid chromatographic separation.

    PubMed

    Bluemlein, Katharina; Raab, Andrea; Feldmann, Jörg

    2009-01-01

    The instability of metal and metalloid complexes during analytical processes has always been an issue of an uncertainty regarding their speciation in plant extracts. Two different speciation protocols were compared regarding the analysis of arsenic phytochelatin (As(III)PC) complexes in fresh plant material. As the final step for separation/detection both methods used RP-HPLC simultaneously coupled to ICP-MS and ES-MS. However, one method was the often used off-line approach using two-dimensional separation, i.e. a pre-cleaning step using size-exclusion chromatography with subsequent fraction collection and freeze-drying prior to the analysis using RP-HPLC-ICP-MS and/or ES-MS. This approach revealed that less than 2% of the total arsenic was bound to peptides such as phytochelatins in the root extract of an arsenate exposed Thunbergia alata, whereas the direct on-line method showed that 83% of arsenic was bound to peptides, mainly as As(III)PC(3) and (GS)As(III)PC(2). Key analytical factors were identified which destabilise the As(III)PCs. The low pH of the mobile phase (0.1% formic acid) using RP-HPLC-ICP-MS/ES-MS stabilises the arsenic peptide complexes in the plant extract as well as the free peptide concentration, as shown by the kinetic disintegration study of the model compound As(III)(GS)(3) at pH 2.2 and 3.8. But only short half-lives of only a few hours were determined for the arsenic glutathione complex. Although As(III)PC(3) showed a ten times higher half-life (23 h) in a plant extract, the pre-cleaning step with subsequent fractionation in a mobile phase of pH 5.6 contributes to the destabilisation of the arsenic peptides in the off-line method. Furthermore, it was found that during a freeze-drying process more than 90% of an As(III)PC(3) complex and smaller free peptides such as PC(2) and PC(3) can be lost. Although the two-dimensional off-line method has been used successfully for other metal complexes, it is concluded here that the fractionation and

  11. Trapped Melt in IIIAB Irons: Solid/Liquid Elemental Partitioning During the Fractionation of the IIIAB Magma

    NASA Technical Reports Server (NTRS)

    Wasson, John T.

    1999-01-01

    Group IIIAB, the largest iron-meteorite group, shows compositional trends (including a three-order-of-magnitude It concentration range) indicating that it formed by fractional crystallization of a metallic magma. Because about 200 irons are available, and all degrees of crystallization are well represented, IIIAB offers an excellent set of samples for the study of crystallization at all depths of the asteroidal core. On log-log Ir-Au, and Ir-As diagrams IIIAB forms a broad band; the breadth represents real meteorite-to-meteorite variations, far outside experimental or sampling uncertainties. A successful model must explain the width of this band; I suggest that it mainly resulted from the trapping of parental magma within the crystallizing solid. Because S is essentially insoluble in metal, the abundance of FeS is a measure of the fraction of trapped liquid. The trapped-melt model is supported by the observation that irons having higher S contents plot closer to the inferred composition of the magmatic parental liquid. The lowest S values are found in the irons occupying the left envelope of the IIIAB Ir-Au or Ir-As compositional fields, thus it is this set of irons that should be interpreted as the solid products of a fractionating magma. This simplifies the modeling of the crystallization process and allows inferences regarding the distribution ratios for other elements in the evolved IIIAB system. The large (multiton) Cape York irons show wide variations in their trapped-melt fractions; their compositions seem best understood in terms of a low initial S content of the IIIAB magma, about 20 mg/g. The inferred initial IIIAB distribution coefficient for Ir, 4.6, is much higher than published values based on laboratory studies of low-S systems; I suggest that low-S (and low-P) partition-ratio measurements tend to err in the direction of unity. In IIIAB distribution coefficients for Au, As, and Ni were still < 1 when the most evolved IIIAB irons formed, another

  12. High-performance liquid chromatographic method with amperometric detection employing boron-doped diamond electrode for the determination of sildenafil, vardenafil and their main metabolites in plasma.

    PubMed

    Bartošová, Zdenka; Jirovský, David; Horna, Aleš

    2011-11-01

    A simple, fast and sensitive HPLC method with electrochemical detection employing boron-doped diamond electrode (BDD) for the determination of sildenafil (Viagra™), vardenafil (Levitra™) and their main metabolites, N-desmethyl sildenafil and N-desethyl vardenafil in human plasma is presented. The assay involved drug extraction by tert-butyl methyl ether and isocratic reversed-phase liquid chromatography with amperometric detection. Complete separation of all analytes was achieved within 12 min. The mobile phase consisted of 20mM sodium dihydrogen phosphate with 40 mM sodium perchlorate/acetonitrile (70:30, v/v), pH 3.5. The electrode working potential was +1520 mV (vs. Pd/H(2)). Calibration curves were linear over the concentration range of 10-400 ng mL(-1). Phloretin was used as an internal standard. The limits of detection (LOD) and quantification (LOQ) for the studied analytes were within the range of 2-4 ng mL(-1) and 7.0-13.4 ng mL(-1), respectively. The developed method was applied to human plasma samples spiked with analytes at therapeutic concentrations. The study confirms the method's suitability for both pharmacokinetic studies and therapeutic monitoring. PMID:21943935

  13. High-performance liquid chromatographic mass spectrometric method for the determination of ursodeoxycholic acid and its glycine and taurine conjugates in human plasma.

    PubMed

    Tessier, E; Neirinck, L; Zhu, Z

    2003-12-25

    A novel sensitive high-performance liquid chromatography-electrospray mass spectrometry method has been developed for the determination of ursodeoxycholic acid (UDCA) and its glycine and taurine conjugates, glycoursodeoxycholic acid (GDCA) and tauroursodeoxycholic acid (TDCA). The procedure involved a solid phase extraction of UDCA, GDCA, TDCA and the internal standard, 23-nordeoxycholic acid from human plasma on a C18 Bond Elut cartridge. Chromatography was performed by isocratic reverse phase separation with methanol/25 mM ammonium acetate (40/60, v/v) containing 0.05% acetic acid on a C18 column with embedded polar functional group. Detection was achieved using an LC-MS/MS system. The standard curve was linear over a working range of 10-3000 ng/ml for all analytes and gave an average correlation coefficient of 0.9992 or better during validation. The absolute recovery for UDCA, GDCA, TDCA and the internal standard was 87.3, 83.7, 79.5 and 95.8%, respectively. This method is simple, sensitive and suitable for pharmacokinetics, bioequivalence or clinical studies. PMID:14643509

  14. Sorption and selective chromatographic properties of isomer-selective composite sorbent based on a eutectic mixture of nematic liquid crystals and perbenzoylated β-cyclodextrin

    NASA Astrophysics Data System (ADS)

    Onuchak, L. A.; Kapralova, T. S.; Kuraeva, Yu. G.; Belousova, Z. P.; Stepanova, R. F.

    2015-12-01

    Mesomorphic, sorption, and selective properties of a three-component sorbent based on a mixture of nematic ( N) liquid crystals of 4-methoxy-4'-ethoxyazoxybenzene (MEAB) and 4,4'-diethoxyazoxybenzene (azoxyphenetol, AOP) of an eutectic composition and heptakis-(2,3,6-tri- O-benzoyl)-β-cyclodextrin (Bz-β-CD) are studied. For 30 organic compounds of different classes with linear and cyclic molecular structures, including optical isomers of limonene, pinene, camphene, and butanediol-2,3, thermodynamic functions are determined for their gas-phase sorption using a three-component MEAB-AOP-Bz-β- CD sorbent (62: 28: 10 wt %). It is found that the investigated sorbent possesses high structural selectivity (αp/m = 1.128-1.059, 100-130°C, N) and moderate enantioselectivity (1.07-1.02) within a broad temperature range (95-170°C) including both mesomorphic and isotropic phases of the sorbent. It is shown that the enantioselectivity of the sorbent is apparent under conditions of both increasing retention when a chiral Bz-β-CD additive is introduced into the MEAB-AOP system (limonenes, pinenes, camphenes) and decreasing retention (butanediols-2,3).

  15. Use of ZIF-8-derived nanoporous carbon as the adsorbent for the solid phase extraction of carbamate pesticides prior to high-performance liquid chromatographic analysis.

    PubMed

    Hao, Lin; Liu, Xingli; Wang, Juntao; Wang, Chun; Wu, Qiuhua; Wang, Zhi

    2015-09-01

    In this work, a chemically and thermally robust and highly porous zeolite-type metal-organic framework, zeolitic imidazolate framework-8 (ZIF-8), was used as both a precursor and a template and furfuryl alcohol as a second precursor to synthesize a nanoporous carbon. The prepared ZIF-8-derived nanoporous carbon was used as the solid-phase extraction adsorbent for the extraction of carbamate pesticides from cabbage and water samples. The adsorbed analytes were eluted with acetonitrile for the determination by high performance liquid chromatography-ultraviolet detection. The high surface area, high porosity, good stability and fast adsorption/desorption kinetics of the material enabled it to have a high adsorption capacity and good adsorption performance. Under optimum conditions, good linearity for the analytes in the range of 0.5-100 ng g(-1) and 0.05-20 ng mL(-1) existed for cabbage and water samples with the correlation coefficients of 0.9968-0.9980 and 0.9990-0.9995, respectively. The limits of detection (S/N=3) for the analytes were in the range of 0.25-0.1 ng g(-1) and 0.01-0.02 ng mL(-1) for the cabbage and water samples, respectively. The relative standard deviations (RSDs) for intra-day and the inter-day determinations of the analytes were below 7.0% and 12.5%, respectively. PMID:26003698

  16. Improvement of the liquid-chromatographic analysis of protein tryptic digests by the use of long-capillary monolithic columns with UV and MS detection.

    PubMed

    van de Meent, M H M; de Jong, G J

    2007-05-01

    Optimisation of peak capacity is an important strategy in gradient liquid chromatography (LC). This can be achieved by using either long columns or columns packed with small particles. Monolithic columns allow the use of long columns at relatively low back-pressure. The gain in peak capacity using long columns was evaluated by the separation of a tryptic bovine serum albumin digest with an LC-UV-mass spectrometry (MS) system and monolithic columns of different length (150 and 750 mm). Peak capacities were determined from UV chromatograms and MS/MS data were used for Mascot database searching. Analyses with a similar gradient slope for the two columns produced ratios of the peak capacities that were close to the expected value of the square root of the column length ratio. Peak capacities of the short column were 12.6 and 25.0 with 3 and 15 min gradients, respectively, and 29.7 and 41.0 for the long column with 15 and 75 min gradients, respectively. Protein identification scores were also higher for the long column, 641 and 750 for the 3- and 15-min gradients with the short column and 1,376 and 993 for the 15- and 75-min gradients with the long column. Thus, the use of long monolithic columns provides improved peptide separation and increased reliability of protein identification. PMID:17393153

  17. Development of a liquid chromatographic method for the quantification of paromomycin. Application to in vitro release and ex vivo permeation studies

    NASA Astrophysics Data System (ADS)

    Pujol-Brugués, A.; Calpena-Campmany, A. C.; Riera-Lizandra, C.; Halbaut-Bellowa, L.; Clares-Naveros, B.

    2014-12-01

    We have developed a reversed phase high performance liquid chromatography pulsed amperometric detection (RPHPLC-PAD) method for the determination of paromomycin. It is sensitive, repeatable, and selective without the pretreatment step. Trifluoroacetic acid-water was utilized as the eluent and detected by PAD under NaOH alkaline conditions. The paromomycin detection limit (S/N = 3.3) was 2 μg mL-1 and the quantification limit (S/N = 10) was 6 μg mL-1. Coefficients of linear regression were higher than 0.99 for concentrations between 6.25 and 200 μg mL-1. The intra and inter-day precision (RSD) was less than 6.5%. The average recoveries were 97.53-102.01%. The proposed HPLC-PAD method presented advantageous performance characteristics and it can be considered suitable for the evaluation of paromomycin loaded nanogel formulation in ex vivo permeation and in vitro release studies.

  18. Liquid chromatographic determination of efficacy of incorporation of trimethoprim and sulfamethoxazole in brine shrimp (Artemia spp.) used for prophylactic chemotherapy of fish.

    PubMed

    Nelis, H J; Léger, F; Sorgeloos, P; De leenheer, A P

    1991-12-01

    The brine shrimp Artemia, an excellent live food source in aquaculture, has been studied as a carrier to deliver selected chemotherapeutic agents to fish for prophylactic treatment of infectious diseases. To monitor the efficiency of incorporation of trimethoprim and sulfamethoxazole in Artemia franciscana, a sensitive and specific analytical method was developed. It is based on homogenization of Artemia nauplii in methanol, extraction of lipids with hexane, solid-phase cleanup on C18 cartridges, and reversed-phase liquid chromatography with detection at 210 nm. The method is sensitive (detection limit, on the order of 3 micrograms/g with a sample quantity of 30 mg [dry weight]) and reproducible (coefficients of variation, 2.2 and 1.8% for trimethoprim and sulfamethoxazole at levels of 79.6 and 257 micrograms/g of body weight, respectively). Preliminary quantitative data indicated excellent uptake and persistence of both therapeutic agents in A. franciscana, with levels of 115 micrograms/g for trimethoprim and 277 micrograms/g for sulfamethoxazole. PMID:1810182

  19. Automated multi-plug filtration cleanup for liquid chromatographic-tandem mass spectrometric pesticide multi-residue analysis in representative crop commodities.

    PubMed

    Qin, Yuhong; Zhang, Jingru; Zhang, Yuan; Li, Fangbing; Han, Yongtao; Zou, Nan; Xu, Haowei; Qian, Meiyuan; Pan, Canping

    2016-09-01

    An automated multi-plug filtration cleanup (m-PFC) method on modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) extracts was developed. The automatic device was aimed to reduce labor-consuming manual operation workload in the cleanup steps. It could control the volume and the speed of pulling and pushing cycles accurately. In this work, m-PFC was based on multi-walled carbon nanotubes (MWCNTs) mixed with other sorbents and anhydrous magnesium sulfate (MgSO4) in a packed tip for analysis of pesticide multi-residues in crop commodities followed by liquid chromatography with tandem mass spectrometric (LC-MS/MS) detection. It was validated by analyzing 25 pesticides in six representative matrices spiked at two concentration levels of 10 and 100μg/kg. Salts, sorbents, m-PFC procedure, automated pulling and pushing volume, automated pulling speed, and pushing speed for each matrix were optimized. After optimization, two general automated m-PFC methods were introduced to relatively simple (apple, citrus fruit, peanut) and relatively complex (spinach, leek, green tea) matrices. Spike recoveries were within 83 and 108% and 1-14% RSD for most analytes in the tested matrices. Matrix-matched calibrations were performed with the coefficients of determination >0.997 between concentration levels of 10 and 1000μg/kg. The developed method was successfully applied to the determination of pesticide residues in market samples. PMID:27507726

  20. Diazepam sorption to PVC- and non-PVC-based tubes in administration sets with quantitative determination using a high-performance liquid chromatographic method.

    PubMed

    Jin, Su-Eon; You, Siwon; Jeon, Seungho; Hwang, Sung-Joo

    2016-06-15

    Diazepam is highly sorbed to the plastic materials of administration sets for intravenous infusion. This can be detrimental as it should be delivered to the patient at the administered amount for efficacy and safety. We report here the sorption levels of diazepam onto various types of tubes in administration sets. The tube materials of the administration sets included polyvinylchloride (PVC) and the non-PVC materials such as polyurethane (PU) and polyolefin (PO) were used. Two conditions of diazepam administered in preclinical and clinical settings were tested using an infusion pump. Injections were prepared by diluting diazepam to 20mg/500mL and 10mg/100mL in 5% dextrose. Diluted diazepam solutions at the concentrations of 10mg/100mL and 20mg/500mL were separately delivered through 1m of tubing at 1mL/min for 1.05 and 4.05h. Samples were analyzed using a high-performance liquid chromatography with UV detection. PVC- and PU-based tubes showed higher sorption of diazepam than did PO-based tubes. PO-based tubes delivered more than 90% of the administered diazepam. The results showed that PO-based tubes of administration sets have a promising potential to deliver hydrophobic drugs like diazepam with minimal sorption levels. In addition, the tube materials in administration sets may be one of the critical factors to ensure drug efficacy and safety. PMID:27091292