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Sample records for liquid chromatographic fractions

  1. Liquid chromatographic fractionations of mixtures of polystyrene oligomers

    SciTech Connect

    Curtis, M A; Webb, J W; Warren, D C; Brandt, V O; Gerberich, F G; Raut, K B; Rogers, L B

    1980-05-24

    Oligomer mixtures of 800, 2200, and 4000 molecular weight polystyrene have been fractionated using silica and bonded phase columns under similar conditions of solvent gradient and flow rate. Using a hexane/tetrahydrofuran gradient, the silica and nitro phases were best in that they separated 41 and 43 oligomers, respectively. At the other extreme, a phenyl bonded phase column gave virtually no resolution using a water/THF gradient and a cyano bonded phase column, using the earlier hexane/tetrahydrofuran system, resolved only 10 oligomers. Amino and octadecyl bonded phase columns gave results intermediate between these two extremes. The strength of the solvent used to dissolve the sample was found to be of critical importance. Use of too good a sample solvent seriously degraded the attainable resolution. When number average and weight average molecular weights for an 800 molecular weight polystyrene sample were calculated from the oligomer distribution, the silica column gave values which were most consistent with those reported from other methods.

  2. Chromatographic methods of fractionation.

    PubMed

    Friesen, A D

    1987-01-01

    Chromatography's functional versatility, separation efficiency, gentle non-denaturing separating process and ease of automation and scale-up make it attractive for industrial scale protein purification. The Winnipeg Rh Institute's new Plasma Fractionation facility is an example of the use of chromatography for the large scale purification of plasma protein fractions. The fractionation facility has a capacity to process 800 litres of plasma per batch into blood clotting factor VIII and IX, albumin and intravenous immune serum globulin (i.v. ISG). Albumin and i.v. ISG are purified using ion exchange columns of DEAE-Sepharose (230 litre size), DEAE-Biogel (150 litre size) and CM-Sepharose (150 litre size). The chromatographic process is automated using a Modicon 584 Programmable Logic Controller to regulate valves, pumps and sensors which control plasma flow during fractionation. The stainless steel tanks and piping are automatically cleaned-in-place. The high degree of automation and cleaning provides efficient operation and sanitary processing. Chromatographic methods (DEAE-Sepharose and metal chelation) are also being used at the pilot scale to purify the human blood products superoxide dismutase and hemoglobin from outdated red blood cells. Characterization of the protein fractions produced by chromatography has shown them to be of equal or higher quality than fractions produced by other techniques.

  3. 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.

  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. 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.

  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. Fractionation of polyphenols in hawthorn into polymeric procyanidins, phenolic acids and flavonoids prior to high-performance liquid chromatographic analysis.

    PubMed

    Svedström, Ulla; Vuorela, Heikki; Kostiainen, Risto; Laakso, Into; Hiltunen, Raimo

    2006-04-21

    Polymeric procyanidins, phenolic carboxylic acids and flavonoids of hawthorn (Crataegus laevigata) were fractionated prior to HPLC analysis using column chromatography and solid-phase extraction (SPE). The flavonoid fraction also contained (-)-epicatechin. The three groups of phenolics, each with clearly different UV spectra, were examined by means of high-performance liquid chromatography-diode array detection (HPLC-DAD) analysis. The average repeatability of the method (RSD) was in the range of 8-13% for chlorogenic acid, (-)-epicatechin and hyperoside. The polymeric procyanidins of hawthorn flowers consisted mainly of (-)-epicatechin subunits, and their mean degree of polymerization (DP) was 22.2. The HPLC methods developed can be used for the qualitative and quantitative analysis of different phenolic compounds in hawthorn plant material and their extracts.

  9. Phenytoin free fraction determination: comparison of an improved direct serum injection high-performance liquid chromatographic method to ultrafiltration coupled with fluorescence polarization immunoassay.

    PubMed

    Gurley, B J; Marx, M; Olsen, K

    1995-08-18

    Recent developments in restricted-access media (RAM) liquid chromatography make the simultaneous determination of total and free phenytoin concentrations possible by direct injection of drug-containing serum samples. A comparison of phenytoin free fraction determination by ultrafiltration coupled with fluorescence polarization immunoassay (TDX) to an improved direct injection RAM-HPLC method is presented. Our improved method differs from those previously reported with regard to column type, mobile-phase composition, and column temperature. Replicate samples analyzed by each method yielded similar values for serum phenytoin free fraction. PMID:8548029

  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. Relating feedstock composition to product slate and composition in catalytic cracking: 1. Bench scale experiments with liquid chromatographic fractions from Wilmington, CA, >650{degree}F resid

    SciTech Connect

    Green, J.B.; Zagula, E.J.; Reynolds, J.W.; Wandke, H.H.; Young, L.L.; Chew, H.

    1993-09-01

    The catalytic cracking behavior of compound types in the >650{degree}F resid from a Wilmington, CA, 14.2{degree} API crude was investigated. Liquid Chromatography (LC) was used to separate the resid into eight fractions. These fractions were used as feedstocks for a bench scale fluidized catalytic cracking (FCC) unit. Gasoline was produced almost exclusively from neutral (65 % of whole resid) components. Acidic and basic types were partially converted to coke plus small amounts of C{sub l} and C{sub 2} gases, with the balance primarily carrying over as heavy liquid products. Gasoline composition depended on the type and quantity of polar compounds present in the feed because both acidic and basic compounds inhibited cracking reactions ({beta}-scission, hydrogen transfer, etc.) to varying degrees. In accordance with prior work, basic nitrogen compounds exhibited the largest inhibitory effect on cracking. Their effect is dependent on concentrations up to a limiting value which may correspond to saturation of susceptible catalyst sites. On an equal weight basis, the effect of high boiling (high molecular weight) bases was less than those occurring in the 650--1000{degree}F distillate range. Partitioning of nitrogen present in acidic (e.g. carbazole) forms in the feed into liquid products was greater than for basic nitrogen. Thiophenic forms of sulfur partitioned more into liquid and less into gaseous (H{sub 2}S) products than sulfide-type sulfur. Coke yield was approximately proportional to microcarbon residue test results for all feeds. Ongoing work with additional feedstocks has indicated behavior similar to that of Wilmington. Selected Wilmington liquid products are undergoing detailed analysis in order to determine relationships between feed versus product composition, particularly with respect to acidic and basic types.

  12. A multi-dimensional high performance liquid chromatographic method for fingerprinting polycyclic aromatic hydrocarbons and their alkyl-homologs in the heavy gas oil fraction of Alaskan North Slope crude.

    PubMed

    Saravanabhavan, Gurusankar; Helferty, Anjali; Hodson, Peter V; Brown, R Stephen

    2007-07-13

    We report an offline multi-dimensional high performance liquid chromatography (HPLC) technique for the group separation and analysis of PAHs in a heavy gas oil fraction (boiling range 287-481 degrees C). Waxes present in the heavy gas oil fraction were precipitated using cold acetone at -20 degrees C. Recovery studies showed that the extract contained 93% (+/-1%; n=3) of the PAHs that were originally present while the wax residue contained only 6% (+/-0.5%; n=3). PAHs present in the extract were fractionated, based on number of rings, into five fractions using a semi-preparative silica column (normal-phase HPLC). These fractions were analyzed using reverse-phase HPLC (RP-HPLC) coupled to a diode array detector (DAD). The method separated alkyl and un-substituted PAHs on two reverse-phase columns in series using an acetonitrile/water mobile phase. UV spectra of the chromatographic peaks were used to differentiate among PAH groups. Further characterization of PAHs within a given group to determine the substituent alkyl carbon number used retention time matching with a suite of alkyl-PAH standards. Naphthalene, dibenzothiophene, phenanthrene and fluorene and their C1-C4 alkyl isomers were quantified. The concentrations of these compounds obtained using the current method were compared with that of a GC-MS analysis obtained from an independent oil chemistry laboratory. PMID:17482627

  13. 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".

  14. 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.

  15. Combined liquid and gas chromatographic characterisation of polyglycerol fatty acid esters.

    PubMed

    De Meulenaer, B; Van Royen, G; Vanhoutte, B; Huyghebaert, A

    2000-10-27

    In the present study a combined liquid and gas chromatographic technique is described for the analysis of polyglycerol fatty acid esters. Liquid chromatographic fractionation of samples resulted in pure standards of monoesters of di- and triglycerols and diesters of di- and triglycerols. Confirmation of their identity was achieved by LC-MS analysis. Moreover, a chromatographic identification of the mono- and diesters of cyclic diglycerol was proposed. From the isolation of pure esters and their gas chromatographic analysis, it was revealed that co-elution of several compounds occurred. Thus it was shown that prefractionation of the sample using a simplified liquid chromatographic separation, was necessary in order to characterise the esters correctly. In combination with some other chemical analyses, a complete profile of the chemical composition of polyglycerol fatty acid esters can be obtained.

  16. 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.

  17. 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.

  18. Emergency gas-chromatographic assay of phenobarbital and phenytoin and liquid-chromatographic assay of theophylline.

    PubMed

    Shihabi, Z K

    1978-09-01

    Phenobarbital and phenytoin are extracted and concentrated in a single step, without solvent evaporation, followed by on-column methylation and gas-chromatographic quanitation. A similar extraction step for the assay of theophylline by high-pressure liquid chromatography is described. The extraction step can be completed in less than 2 min, the chromatographic step in less than 8 min. This extraction method yields clean chromatograms, avoids evaporating health-hazardous solvents, and is applicable to other drugs.

  19. Chromatographic analysis of olopatadine in hydrophilic interaction liquid chromatography.

    PubMed

    Maksić, Jelena; Jovanović, Marko; Rakić, Tijana; Popović, Igor; Ivanović, Darko; Jančić-Stojanović, Biljana

    2015-01-01

    In this paper, chromatographic analysis of active substance olopatadine hydrochloride, which is used in eye drops as antihistaminic agent, and its impurity E isomer by hydrophilic interaction liquid chromatography (HILIC) and application of design of experiments (DoE) methodology are presented. In addition, benzalkonium chloride is very often used as a preservative in eye drops. Therefore, the evaluation of its chromatographic behavior in HILIC was carried out as well. In order to estimate chromatographic behavior and set optimal chromatographic conditions, DoE methodology was applied. After the selection of important chromatographic factors, Box-Behnken design was utilized, and on the basis of the obtained models factor effects were examined. Then, multi-objective robust optimization is performed aiming to obtain chromatographic conditions that comply with several quality criteria simultaneously: adequate and robust separation of critical peak pair and maximum retention of the first eluting peak. The optimal conditions are identified by using grid point search methodology. The experimental verification confirmed the adequacy of the defined optimal conditions. Finally, under optimal chromatographic conditions, the method was validated and applicability of the proposed method was confirmed.

  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. [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

  2. [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.

  3. 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.

  4. [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.

  5. Liquid chromatographic analysis of coal surface properties

    SciTech Connect

    Kwon, K.C.

    1991-01-01

    The main objectives of this proposed research 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 floatability of various treated coals in conjunction with surface properties of coals. Alcohols such as methanol, ethanol, isopropanol, isobutanol, tert-butanol, heptanol, 1-hexadecanol, 2-methyl-pentanol, 4-methyl-2-penthanol (methylisobutyl carbinol), n-octanol, s-octanol, and cyclohexanol as probe compounds are utilized to evaluate hydrophilicity of coals and coal minerals. N-alkanes such as hexane, heptane and octane, and stearic acid are employed as probe compounds to evaluate hydrophobicity of coals and coal minerals. Aromatic compounds such as benzene and toluene as probe compounds are used to examine aromaticity of coal surface. Aromatic acids such as o-cresol, m-cresol, p-cresol, phenol and B-naphthol are used to detect aromatic acidic sites of coal surface. Hydrophilicity, hydrophobicity and aromaticity of surfaces for either raw coals or treated coals in water are relatively determined by evaluating both equilibrium physical/chemical adsorption and dynamic adsorption of probe compounds on various raw coals and treated coals to compare affinities of coals for water.

  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.

  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. Liquid chromatographic determination of ethylenethiourea using pulsed amperometric detection.

    PubMed

    Doerge, D R; Yee, A B

    1991-11-01

    A liquid chromatographic method was developed using pulsed amperometric detection at a gold working electrode to measure residue levels of ethylenethiourea (ETU) in crops and groundwater. Use of the sequential pulsing program eliminates electrode fouling while preserving the sensitive and selective detection of ETU. Minimum detection limits in crops were 5-10 ppb (1.25-2.5 ng on-column) and 5 ppb (0.5 ng) in groundwater. The commercial availability of the pulsed electrochemical detector and its gold working electrode that remains functional with a minimum of conditioning is an improvement in method simplicity.

  9. Fundulus heteroclitus gonadotropins.5: Small scale chromatographic fractionation of pituitary extracts into components with different steroidogenic activities using homologous bioassays

    PubMed Central

    Lin, Yu-Wai Peter; Petrino, Teresa R; Wallace, Robin A

    2004-01-01

    Fractionation and characterization of gonadotropins (GtH) from Fundulus heteroclitus pituitary extracts were carried out using a biocompatible liquid chromatographic procedure (Pharmacia FPLC system). Chromatographic fractions were monitored for gonadotropic activities (induction of oocyte maturation and steroid production) using homologous follicle bioassays in vitro. Size-exclusion chromatography eluted gonadotropic activity in one major protein peak (Mr ~ 30,000). Anion-exchange and hydrophobic-interaction chromatography (HIC) yielded two distinct peaks of 17beta-estradiol (E2)- and 17alpha-hydroxy,20beta-dihydroprogesterone (DHP)-promoting activity with associated oocyte maturation. Two-dimensional chromatography (chromatofocusing followed by HIC) resolved pituitary extracts into two active fractions; both induced E2 synthesis, but one was relatively poor in eliciting DHP and testosterone production. Thus, using homologous bioassays, at least two quantitatively different gonadotropic (steroidogenic) activities: an E2-promoting gonadotropin (GtH I-like) and a DHP-promoting gonadotropin (GtH II-like), which has a lower isoelectric point but greater hydrophobicity than the former, can be distinguished from F. heteroclitus pituitaries by a variety of chromatographic procedures. This study complements previous biochemical and molecular data in F. heteroclitus and substantiates the duality of GtH function in a multiple-spawning teleost. PMID:15040801

  10. Liquid chromatographic determination of vitamin B-6 in foods.

    PubMed

    Vanderslice, J T; Brownlee, S R; Cortissoz, M E

    1984-01-01

    Chromatographic analysis for vitamin B-6 in complex samples imposes certain requirements on the analyst, who must extract completely the bound, unstable vitamers without loss, remove interfering compounds, and provide clean extracts for analysis. The analyst also has to contend with the problems inherent in all methods, such as sample collection, storage, preparation, and homogenization. However, chromatography provides a means of identifying and quantitating all forms of the vitamin, and thus provides the possibility of addressing the problem of the bioavailability of specific vitamers. It also allows automation, which is absolutely essential in coping with the large numbers of samples that are generated in areas such as quality control. These factors are all addressed here, and chromatographic results for various meat and other food products are presented to illustrate the variations in vitamin content that occur from sample to sample, the agreement with microbiological results, and that liquid chromatography (LC) has come of age in dealing with complex biological samples, such as food and food products.

  11. Liquid chromatographic determination of carminic acid in yogurt.

    PubMed

    Jalón, M; Peña, M J; Rivas, J C

    1989-01-01

    A reverse-phase liquid chromatographic method is described for the determination of carminic acid in yogurt. A C18 column is used with acetonitrile-1.19M formic acid (19 + 81) as mobile phase and diode array detection. Sample preparation includes deproteinization with papain and purification in a polyamide column. The relative standard deviation for repeated determinations of carminic acid in a commercial strawberry-flavored yogurt was 3.0%. Recoveries of carminic acid added to a natural-flavored yogurt ranged from 87.2 to 95.3% with a mean of 90.2%. The method permits measurement of amounts as low as 0.10 mg/kg. PMID:2708269

  12. 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.

  13. Liquid chromatographic determination of amphotericin B in different pharmaceuticals.

    PubMed

    Lue, Louis P; Hadman, Susan T; Vancura, Ales

    2002-01-01

    Amphotericin B (AmB) is one of the most potent antifungal agents and the drug of choice in the treatment of serious fungal infections. A liquid chromatographic (LC) method was developed to determine AmB in pharmaceutical formulations for injection, tissue culture, cream, and lotion. pBondapak C18 reversed-phase column and a simple mobile phase consisting of acetonitrile-water-acetic acid (40 + 54 + 6, v/v) was used. The flow rate was 1.8 mL/min and the effluent was monitored at 405 nm. The developed LC method uses piroxicam as an internal standard and has a limit of detection of 10 ng/mL, a limit of quantitation of 30 ng/mL, and the assay is linear from 0.01 to 100 microg/mL. AmB and piroxicam elute with retention times of 12.4 and 4.0 min, respectively, and the resolution between AmB and piroxicam was 10.6. In comparison with the official United States Pharmacopeia microbial assay for AmB, this LC method is more rapid, selective, sensitive, and offers positive identification.

  14. Reverse phase liquid chromatographic determination of some food additives.

    PubMed

    Veerabhadrarao, M; Narayan, M S; Kapur, O

    1987-01-01

    Liquid chromatographic methods are described for the separation and determination of non-nutritive sweeteners, namely, acesulfame, aspartame, saccharin, and dulcin; preservatives such as benzoic acid and p-hydroxybenzoic acid; and caffeine and vanillin in ready-to-serve beverages, ice candy, ice cream, squash beverage, tomato sauce, and dry beverage mix samples. These additives are separated on a muBondapak C18 column using methanol-acetic acid-water (20 + 5 + 75) as mobile phase and detected by UV absorption at 254 nm. Caffeine, vanillin, dulcin, and benzoic acid can be analyzed quickly by using a mobile phase of methanol-acetic acid-water (35 + 5 + 60). Aspartame can be separated in the presence of caffeine and vanillin by using the mobile phase pH 3 acetate buffer-methanol (95 + 5). Retention factors and minimum detectable limits are described. The percentage error and the percent relative standard deviation for 6 replicate samples ranged from 0.3 to 2.8 and from 1.64 to 3.60, respectively. Recovery of additives added to the foods named and analyzed by the direct method and by extraction ranged from 98.0 to 100.6% and from 91.6 to 101.8%, respectively. The proposed LC techniques are simple, rapid, and advantageous because all the additives can be detected in a single step, which makes it useful for the routine analysis of various food products.

  15. 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.

  16. HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC SEPARATION OF THE ENANTIOMERS OF ORGANOPHOSPHORUS PESTICIDES ON POLYSACCHARIDE CHIRAL STATIONARY PHASES

    EPA Science Inventory

    High-performance liquid chromatographic separation of the individual enantiomers of 12 organophosphorus pesticides (OPs) was obtained on polysaccharide enantioselective HPLC columns using alkane-alcohol mobile phase. The OP pesticides were crotoxyphos, dialifor, fonofos, fenamiph...

  17. 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.

  18. Liquid chromatographic determination of benzo(a)pyrene in natural, synthetic, and refined crudes

    SciTech Connect

    Tomkins, B.A.; Reagan, R.R.; Caton, J.E.; Griest, W.H.

    1981-07-01

    Benzo(a)pyrene (BaP) is isolated and quantitated by using a sequential high-pressure liquid chromatographic (HPLC) procedure. The sample is first injected onto a semipreparative HPLC column containing a bonded polar aminocyano (PAC) packing material, from which a BaP-enriched fraction is obtained. This isolate is then reinjected onto a Zorbax ODS reversed-phase analytical-scale column, and fluorescence detection is used to quantitate BaP. This procedure is applicable to samples with BaP concentrations ranging from 0.02 to 500 ..mu..g/g. The precision is nominally +- 6% (relative standard deviation), and the accuracy compares favorably with that displayed by more tedious methods. Recoveries, as determined by counting a radioactive BaP tracer, usually exceed 95%. Two samples may be processed per person-day.

  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. Holographic Metals and the Fractionalized Fermi Liquid

    SciTech Connect

    Sachdev, Subir

    2010-10-08

    We show that there is a close correspondence between the physical properties of holographic metals near charged black holes in anti-de Sitter (AdS) space, and the fractionalized Fermi liquid phase of the lattice Anderson model. The latter phase has a ''small'' Fermi surface of conduction electrons, along with a spin liquid of local moments. This correspondence implies that certain mean-field gapless spin liquids are states of matter at nonzero density realizing the near-horizon, AdS{sub 2}xR{sup 2} physics of Reissner-Nordstroem black holes.

  1. Holographic metals and the fractionalized fermi liquid.

    PubMed

    Sachdev, Subir

    2010-10-01

    We show that there is a close correspondence between the physical properties of holographic metals near charged black holes in anti-de Sitter (AdS) space, and the fractionalized Fermi liquid phase of the lattice Anderson model. The latter phase has a "small" Fermi surface of conduction electrons, along with a spin liquid of local moments. This correspondence implies that certain mean-field gapless spin liquids are states of matter at nonzero density realizing the near-horizon, AdS₂ × R² physics of Reissner-Nordström black holes. PMID:21230891

  2. 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.

  3. Measurement uncertainty of liquid chromatographic analyses visualized by Ishikawa diagrams.

    PubMed

    Meyer, Veronika R

    2003-09-01

    Ishikawa, or cause-and-effect diagrams, help to visualize the parameters that influence a chromatographic analysis. Therefore, they facilitate the set up of the uncertainty budget of the analysis, which can then be expressed in mathematical form. If the uncertainty is calculated as the Gaussian sum of all uncertainty parameters, it is necessary to quantitate them all, a task that is usually not practical. The other possible approach is to use the intermediate precision as a base for the uncertainty calculation. In this case, it is at least necessary to consider the uncertainty of the purity of the reference material in addition to the precision data. The Ishikawa diagram is then very simple, and so is the uncertainty calculation. This advantage is given by the loss of information about the parameters that influence the measurement uncertainty.

  4. 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...

  5. High-performance liquid chromatographic-fluorometric determination of cinnamaldehyde in perfume, cologne and toilet water.

    PubMed

    Wisneski, H H; Yates, R L; Davis, H M

    1984-12-28

    A high-performance liquid chromatographic (HPLC)-fluorometric method is described for the determination of trans-cinnamaldehyde in fragrances. The fragrance is added to isooctane and extracted with an aqueous solution of the sodium salt of 6-aminocaproic acid to isolate the aldehyde fraction. After dilution with water, an aliquot of the extract is added to a solution of 1,2-diaminonaphthalene monosulfate in dilute formic acid. The fluorescent derivative of cinnamaldehyde, 2-styrylnaphth[1,2-d]imidazole, is prepared by incubating and then cooling the solution and adding pyridine. Aliquots of the fluorophore solution are analyzed on a reversed-phase C18 HPLC column by using a buffered tetrahydrofuran-water eluent. Cinnamaldehyde is quantitated by comparing fluorescence emission intensity with that of a standard. Recoveries from samples of various commercial fragrances, spiked with cinnamaldehyde at the 0.01, 0.05 and 0.1% levels, ranged from 94 to 112% with a mean of 103% and a standard deviation of 5.3. The limit of detection is approximately 1 ng.

  6. Acrylamide analysis in food by liquid chromatographic and gas chromatographic methods.

    PubMed

    Elbashir, Abdalla A; Omar, Mei M Ali; Ibrahim, Wan Aini Wan; Schmitz, Oliver J; Aboul-Enein, Hassan Y

    2014-01-01

    Acrylamide (AA) is a compound classified as carcinogenic to humans by the International Agency for Research on Cancer. It was first discovered to be present in certain heated processed food by the Swedish National Food Administration (SNFA) and University of Stockholm in early 2002. The major pathway for AA formation in food is the Maillard reaction between reducing sugar and the amino acid asparagine at high temperature. Since the discovery of AA's presence in food, many analytical methods have been developed for determination of AA contents in different food matrices. Also, several studies have been conducted to develop extraction procedures for AA from difficult food matrices. AA is a small, highly polar molecule, which makes its extraction and analysis challenging. Many articles and reviews have been published dealing with AA in food. The aim of the review is to discuss AA formation in food, the factors affecting AA formation and removal, AA exposure assessment, AA extraction and cleanup from food samples, and analytical methods used in AA determination, such as high-performance liquid chromatography (HPLC) and gas chromatography (GC). Special attention is given to sample extraction and cleanup procedures and analytical techniques used for AA determination.

  7. 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

  8. 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

  9. 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.

  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.

  11. 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)

  12. 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...

  13. 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.

  14. 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.

  15. Combination of MS protein identification and bioassay of chromatographic fractions to identify biologically active substances from complex protein sources.

    PubMed

    Kuromitsu, Sadao; Yokota, Hiroyuki; Hiramoto, Masashi; Yuri, Masatoshi; Naitou, Masanori; Nakamura, Naoto; Kawabata, Shigeki; Kobori, Masato; Katoh, Masao; Furuchi, Kiyoshi; Mita, Haruhisa; Yamada, Tetsuo

    2009-06-01

    Purification of biologically active proteins from complex biological sources is a difficult task, usually requiring large amounts of sample and many separation steps. We found an active substance in a serum response element-dependent luciferase reporter gene bioassay in interstitial cystitis urine that we attempted to purify with column chromatography and the bioassay. With anion-exchange Mono Q and C4 reversed-phase columns, apparently sharp active peaks were obtained. However, more than 20 kinds of proteins were identified from the active fractions with MS, indicating that the purification was not complete. As further purification was difficult, we chose a candidate molecule by means of studying the correlation between MS protein identification scores and bioassay responses of chromatographic fractions near the active peaks. As a result, epidermal growth factor (EGF) was nominated as a candidate molecule among the identified proteins because the elution profile of EGF was consistent with that of the bioassay, and the correlation coefficient of EGF between MS protein identification scores and bioassay responses was the highest among all the identified proteins. With recombinant EGF and anti-EGF and anti-EGF receptor antibodies, EGF was confirmed to be the desired substance in interstitial cystitis urine. This approach required only 20 ml of urine sample and two column chromatographic steps. The combination of MS protein identification and bioassay of chromatographic fractions may be useful for identifying biologically active substances from complex protein sources.

  16. Liquid chromatographic determination of beta-cyclodextrin derivatives based on fluorescence enhancement after inclusion complexation.

    PubMed

    Reeuwijk, H J; Irth, H; Tjaden, U R; Merkus, F W; van der Greef, J

    1993-04-21

    A liquid chromatographic method using fluorescence detection for the determination of beta-cyclodextrin (beta CD) and its derivatives is presented. The chromatographic system is based on size-exclusion chromatography with the addition of the fluorophoric compound 1-naphthol to the mobile phase. Detection is based on fluorescence enhancement caused by the formation of inclusion complexes. By incorporating 10(-4) M 1-naphthol in the mobile phase, detection limits of 90, 27, 370 and 37 pmol were obtained for beta CD, hydroxypropyl-beta CD, trimethyl-beta CD and dimethyl-beta CD, respectively. The method was applied to the determination of dimethyl-beta CD in urine: the minimum detectable concentration was 0.2 microgram/ml after preconcentration of 10 ml of urine.

  17. High-performance liquid chromatographic assay for cinnarizine in human plasma.

    PubMed

    Nowacka-Krukowska, Hanna; Rakowska, Monika; Neubart, Kinga; Kobylińska, Maria

    2007-01-01

    The high performance liquid chromatography for the determination of cinnarizine in human plasma is described. The procedure involves liquid-liquid extraction followed by reversed phase high-performance chromatographic analysis with fluorometric detection. The method was validated for accuracy, precision, specificity, linearity, sensitivity, recovery, and stability. No endogenous compounds were found to interfere. The absolute extraction recovery of cinnarizine and clocinizine (internal standard) from plasma samples were 97% and 89%, respectively. The linearity was assessed in the range 1-100 ng/mL. The intra-day and inter-day relative standard deviations were less than 10%, and the accuracy of the assay expressed by bias was in the range 0.14-2.37%. The method was proved to be suitable for human pharmacokinetic studies following single oral dose. PMID:18540159

  18. 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

  19. Determinations of gas-liquid partition coefficients using capillary chromatographic columns. Alkanols in squalane.

    PubMed

    Tascon, Marcos; Romero, Lílian M; Acquaviva, Agustín; Keunchkarian, Sonia; Castells, Cecilia

    2013-06-14

    This study focused on an investigation into the experimental quantities inherent in the determination of partition coefficients from gas-liquid chromatographic measurements through the use of capillary columns. We prepared several squalane - (2,6,10,15,19,23-hexamethyltetracosane) - containing columns with very precisely known phase ratios and determined solute retention and hold-up times at 30, 40, 50 and 60°C. We calculated infinite dilution partition coefficients from the slopes of the linear regression of retention factors as a function of the reciprocal of the phase ratio by means of fundamental chromatographic equations. In order to minimize gas-solid and liquid-solid interface contributions to retention, the surface of the capillary inner wall was pretreated to guarantee a uniform coat of stationary phase. The validity of the proposed approach was first tested by estimating the partition coefficients of n-alkanes between n-pentane and n-nonane, for which compounds data from the literature were available. Then partition coefficients of sixteen aliphatic alcohols in squalane were determined at those four temperatures. We deliberately chose these highly challenging systems: alcohols in the reference paraffinic stationary phase. These solutes exhibited adsorption in the gas-liquid interface that contributed to retention. The corresponding adsorption constant values were estimated. We fully discuss here the uncertainties associated with each experimental measurement and how these fundamental determinations can be performed precisely by circumventing the main drawbacks. The proposed strategy is reliable and much simpler than the classical chromatographic method employing packed columns.

  20. 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.

  1. High-performance liquid chromatographic determination of dimethyldithiocarbamate residues in some agricultural products.

    PubMed

    Brandsteterová, E; Lehotay, J; Liska, O; Garaj, J

    1986-02-28

    Dimethyldithiocarbamates are widely used in agriculture as active fungicides. The degradation of dimethyldithiocarbamates (ferbam, thiram) confirmed the fact that they are not stable and decompose very rapidly. The aim of this work was to apply the results obtained in high-performance liquid chromatographic quantitative analysis of residues of dithiocarbamate fungicides in some agricultural products (strawberries, maize, tobacco). The developed method enables very simple control analysis of low concentrations of dimethyldithiocarbamate residues in very short time. All limits of detection correspond with the criteria of FAO (Codex Alimentarius).

  2. Stereoselective high-performance liquid chromatographic determination of flurbiprofen in human plasma.

    PubMed

    Geisslinger, G; Menzel-Soglowek, S; Schuster, O; Brune, K

    1992-01-01

    An enantioselective high-performance liquid chromatographic assay for the quantitation of the enantiomers of flurbiprofen in human plasma is described. The procedure involved extraction of flurbiprofen from acidified plasma into hexane-diethyl ether (8:2, v/v). Stereoselective separation was achieved with a prepacked alpha 1-acid glycoprotein column without any derivatization procedure. A second assay using a conventional reversed-phase column to determine racemic flurbiprofen is also described. The detection wavelength was set at 246 nm. The limit of quantification was found to be 50 ng/ml for both assays. The method was demonstrated to be sufficiently sensitive for stereoselective pharmacokinetic studies of flurbiprofen.

  3. On-line sample cleanup in the liquid chromatographic analysis of pharmaceuticals for citrate content.

    PubMed

    Burke, E; Zimmerman, S R; Brown, D S; Jenke, D R

    1988-10-01

    Matrix interferents are removed from pharmaceutical samples via an on-line, automated column switching process in which the difference in hydrophobicity between the analyte and the interferents allows these species to be isolated in different parts of the chromatographic system. In this case, the interferents are trapped on a cleanup column and are flushed to waste as the analyte undergoes additional separation on an analytical column. The utility of this approach is demonstrated by the quantitation of citrate in pharmaceutical samples by ion suppression, reversed-phase liquid chromatography. The performance of this system is statistically equivalent to that of a manual pretreatment method employing disposable, solid-phase extraction cartridges.

  4. A liquid chromatographic method for determination of theophylline in serum and capillary blood--a comparison.

    PubMed

    Gartzke, J; Jäger, H; Vins, I

    1991-01-01

    A simple, fast and reliable liquid chromatographic method for the determination of theophylline in serum and capillary blood after a solid phase extraction is described for therapeutic drug monitoring. The employment of capillary blood permits the determination of an individual drug profile and other pharmacokinetic studies in neonates and infants. There were no differences in venous- and capillary-blood levels but these values compared poorly with those in serum. An adjustment of the results by correction of the different volumes of serum and blood by haematocrit was unsuccessful. Differences in the binding of theophylline to erythrocytes could be an explanation for the differences in serum at blood levels of theophylline.

  5. 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%.

  6. Two high-performance liquid chromatographic methods for quantitation of theophylline in plasma.

    PubMed

    Park, Y H; Goshorn, C; Hinsvark, O

    1985-10-11

    Two high-performance liquid chromatographic methods are described for the assay of theophylline in plasma. Both allowed the separation of theophylline from the caffeine metabolites, theobromine and 1,7-dimethylxanthine. Method A, using 8-chlorotheophylline as internal standard, involved back extraction of theophylline from organic extract with 0.1 M sodium hydroxide. Method B used generally accepted solvent extraction followed by evaporation and beta-hydroxyethyltheophylline as internal standard. High-performance liquid chromatographic analyses were performed on reversed-phase phenyl columns (25 X 0.46 and 25 X 0.41 cm) using 20% methanol in 20 mM phosphate buffer at pH 5.6 for Method A and 2% acetonitrile and 8% methanol in 20 mM phosphate buffer for Method B. The column effluent was monitored at UV 273 nm. Standard curves for both Methods A and B were fitted by linear regression (r greater than 0.999) in the concentration range of 0.05-50 micrograms/ml. Either method was selective, accurate and reproducible over the concentration range 0.08-26 micrograms/ml. However, compared with Method B, Method A provided significant advantages in terms of simplicity, speed and efficiency.

  7. Determination of metal ions by high-performance liquid chromatographic separation of their hydroxamic acid chelates

    SciTech Connect

    Palmieri, M.D.; Fritz, J.S.

    1987-09-15

    Metal ions are determined by adding N-methylfurohydroxamic acid to an aqueous sample and then separating the metal chelates by direct injection onto a liquid chromatographic column. Separations on a C/sub 8/ silica column and a polystyrene-divinylbenzene column are compared, with better separations seen on the polymeric column. The complexes formed at low pH values are cationic and are separated by an ion pairing mechanism. Retention times and selectivity of the metal complexes can be varied by changing the pH. Several metal ions can be separated and quantified; separation conditions, linear calibration curve ranges, and detection limits are presented for Zr(IV), Hf(IV), Fe(III), Nb(V), Al(III), and Sb(III). Interferences due to the presence of other ions in solution are investigated. Finally, an antiperspirant sample is analyzed for zirconium by high-performance liquid chromatography.

  8. Gas-liquid chromatographic headspace technique for determination of vinyl chloride in corn oil and three food-simulating solvents.

    PubMed

    Diachenko, G W; Breder, C V; Brown, M E; Dennison, J L

    1977-05-01

    A gas-liquid chromatographic headspace technique for the determination of vinyl chloride (VC) in corn oil, 50% ethanol, 3% acetic acid, and n-heptane is described. These food-simulating solvents and the corn oil are placed in septum-sealed bottles and heated to 90 degrees C, and aliquots of headspace vapor are injected into a gas-liquid chromatograph equipped with a flame ionization detector. VC may be quantitated at concentrations of 1 ppb or less. This technique was used to measure the migration of VC into corn oil and 50% ethanol from 2 unplasticized polyvinyl chloride sheets containing 0.28 and 0.44 ppm residual monomer.

  9. Multi-channel open tubular traps for headspace sampling, gas chromatographic fraction collection and olfactory assessment of milk volatiles.

    PubMed

    Naudé, Yvette; van Aardt, Marleen; Rohwer, Egmont Richard

    2009-04-01

    A headspace sampling method is described for concentrating milk volatiles onto a multi-channel open tubular silicone rubber trap (MCT) for thermal desorption into a GC-FID. Sections of the chromatographic profile, single peaks or combinations of compounds are recaptured with secondary MCTs during a subsequent run. The recaptured aroma is released in a controlled manner by heating the MCT in a portable heating device. An aroma release window of several minutes allows up to six people the opportunity to sniff each aroma fraction more than once. Olfactory results suggest that a synergistic combination of 2-heptanone and 2-nonanone could be responsible for a pungent cheese, sour milk-like aroma. MCTs containing single components or fractions can be desorbed into a GC-MS for compound identification.

  10. 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

  11. Liquid Chromatographic Determination of Linagliptin in Bulk, in Plasma and in its Pharmaceutical Preparation

    PubMed Central

    El-Bagary, Ramzia I.; Elkady, Ehab F.; Ayoub, Bassam M.

    2012-01-01

    In this work, two reversed-phase liquid chromatographic (RP-LC) methods have been developed for the determination of linagliptin (LNG) based on isocratic elution using a mobile phase consisting of potassium dihydrogen phosphate buffer pH (4.6)-acetonitrile(20:80, v/v) at a flow rate of 1 mL min−1. Two detection techniques have been applied either UV detection at 299 nm in the first method or fluorometric detection at 239 nm for excitation and 355 nm for emission in the second method. Chromatographic separation in the two methods was achieved on a Symmetry® cyanide column (150 mm × 4.6 mm, 5 μm). Linearity, accuracy and precision were found to be acceptable over the concentration ranges of 2.5-80 μg mL−1 for LNG in bulk and 2.5-15 μg mL−1 for LNG in plasma with the first method and 5-160 μg mL−1 for LNG in bulk with the second method. The optimized methods were validated and proved to be specific, robust and accurate for the quality control of the cited drug in its pharmaceutical preparation. PMID:23675275

  12. Development and Validation of Reversed-Phase High Performance Liquid Chromatographic Method for Hydroxychloroquine Sulphate

    PubMed Central

    Singh, A.; Roopkishora; Singh, C. L.; Gupta, R.; Kumar, S.; Kumar, M.

    2015-01-01

    In the present work new, simple reversed-phase high performance liquid chromatographic method was developed and validated for the determination of hydroxychloroquine sulphate in blood plasma. Chloroquine sulphate was used as an internal standard. The chromatographic separation was achieved with octadecyl silane Hypersil C18 column (250×6 mm, 5 μm) using water and organic (acetonitrile:methanol: 50:50, v/v) mobile phase in 75:25 v/v ratio, with sodium 1-pentanesulfonate and phosphoric acid. This organic phase was maintained at pH 3.0 by orthophosphoric acid. The flow rate of 2.0 ml/min. with detection at 343 nm was used in the analysis. The calibration curve of standard hydroxychloroquine sulphate was linear in range 0.1-20.0 μg/ml. The method was validated with respected to linearity, range, precision, accuracy, specificity and robustness studies according to ICH guidelines. The method was found to be accurate and robust to analyze the hydroxychloroquine sulphate in plasma samples. PMID:26798174

  13. Development and Validation of Reversed-Phase High Performance Liquid Chromatographic Method for Hydroxychloroquine Sulphate.

    PubMed

    Singh, A; Roopkishora; Singh, C L; Gupta, R; Kumar, S; Kumar, M

    2015-01-01

    In the present work new, simple reversed-phase high performance liquid chromatographic method was developed and validated for the determination of hydroxychloroquine sulphate in blood plasma. Chloroquine sulphate was used as an internal standard. The chromatographic separation was achieved with octadecyl silane Hypersil C18 column (250×6 mm, 5 μm) using water and organic (acetonitrile:methanol: 50:50, v/v) mobile phase in 75:25 v/v ratio, with sodium 1-pentanesulfonate and phosphoric acid. This organic phase was maintained at pH 3.0 by orthophosphoric acid. The flow rate of 2.0 ml/min(.) with detection at 343 nm was used in the analysis. The calibration curve of standard hydroxychloroquine sulphate was linear in range 0.1-20.0 μg/ml. The method was validated with respected to linearity, range, precision, accuracy, specificity and robustness studies according to ICH guidelines. The method was found to be accurate and robust to analyze the hydroxychloroquine sulphate in plasma samples. PMID:26798174

  14. Validation of a liquid chromatographic method for determination of tacrolimus in pharmaceutical dosage forms.

    PubMed

    Moyano, María A; Simionato, Laura D; Pizzorno, María T; Segall, Adriana I

    2006-01-01

    An accurate, simple, and reproducible liquid chromatographic method was developed and validated for the determination of tacrolimus in capsules. The analysis is performed at room temperature on a reversed-phase C18 column with UV detection at 210 nm. The mobile phase is methanol-water (90 + 10) at a constant flow rate of 0.8 mL/min. The method was validated in terms of linearity, precision, accuracy, and specificity by forced decomposition of tacrolimus, using acid, base, water, hydrogen peroxide, heat, and light. The response was linear in the range of 0.09-0.24 mg/mL (r2 = 0.9997). The relative standard deviation values for intra- and interday precision studies were 1.28 and 2.91%, respectively. Recoveries ranged from 98.06 to 102.52%.

  15. Gas-liquid chromatographic properties of positional isomers of methyl thia, selena, and tellura laurate analogs.

    PubMed

    Jie, M S; Bakare, O; Cheung, Y K; Chau, S H

    1997-06-01

    Gas-liquid chromatographic analyses of three complete series of synthetic positional isomers of methyl thia, selena, and tellura laurate analogs were carried on a nonpolar (SE-30) and a polar (SP-2330) stationary phase. The average ECL (equivalent chain length) values of the thia, selena, and tellura laurate on SE-30 stationary phase were 13.8, 14.8, and 15.7, respectively, while on SP-2330 the average values for the same series were 17.1, 19.0, and 19.1, respectively. Positional isomers with the heteroatom at the 2-position exhibited the lowest ECL values, while those with the heteroatom at the omega-1 position gave the highest ECL values and were readily separated from the other positional isomers of the same series of analogs by this technique.

  16. Solid-phase extraction and liquid chromatographic quantitation of quinfamide in biological samples.

    PubMed

    Morales, J M; Jung, C H; Alarcón, A; Barreda, A

    2000-09-15

    This paper describes a high-performance liquid chromatographic method for the assay of quinfamide and its main metabolite, 1-(dichloroacetyl)-1,2,3,4,-tetrahydro-6-quinolinol, in plasma, urine and feces. It requires 1 ml of biological fluid, an extraction using Sep-Pack cartridges and acetonitrile for drug elution. Analysis was performed on a CN column (5 microm) using water-acetonitrile-methanol (40:50:10) as a mobile phase at 269 nm. Results showed that the assay was linear in the range between 0.08 and 2.0 microg/ml. The limit of quantitation was 0.08 microg/ml. Maximum assay coefficient of variation was 14%. Recovery obtained in plasma, urine and feces ranged from 82% to 98%.

  17. Liquid chromatographic-fluorometric determination of cinnamyl alcohol in perfumes, colognes, and toilet waters.

    PubMed

    Wisneski, H H; Yates, R L; Wenninger, J A

    1988-01-01

    A liquid chromatographic (LC) method is described for the determination of cinnamyl alcohol (3-phenyl-2-propen-1-ol) in fragrance compositions. The fragrance product is partially cleaned up by diluting the fragrance with a 95% ethanol-water mixture and passing it through a short column containing RP-8 packing. An aliquot of the effluent is then analyzed by LC using an RP-18 column interfaced to a spectrophotofluorometer equipped with double monochromators. The fluorescence emission intensity of the eluted cinnamyl alcohol is measured and compared with that of a standard to calculate the amount of cinnamyl alcohol present. Recoveries from fragrance products fortified with cinnamyl alcohol at levels ranging from 0.0020 to 0.060 mg/mL ranged from 85 to 105% with a mean of 94%. The lowest level of determination was 0.0005 mg/mL.

  18. 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

  19. Uncertainty in liquid chromatographic analysis of pharmaceutical product: influence of various uncertainty sources.

    PubMed

    Leito, Signe; Mölder, Kadi; Künnapas, Allan; Herodes, Koit; Leito, Ivo

    2006-07-14

    An ISO GUM measurement uncertainty estimation procedure was developed for a liquid-chromatographic drug quality control method-assay of simvastatin in drug formulation. In quantification of uncertainty components several practical approaches for including difficult-to-estimate uncertainty sources (such as uncertainty due to peak integration, uncertainty due to nonlinearity of the calibration curve, etc.) have been presented. Detailed analysis of contributions of the various uncertainty sources was carried out. The results were calculated based on different definitions of the measurand and it was demonstrated that unequivocal definition of the measurand is essential in order to get rigorous uncertainty estimate. Two different calibration methods - single-point (1P) and five-point (5P) - were used and the obtained uncertainties and uncertainty budgets were compared. Results calculated using 1P and 5P calibrations agree very well. The uncertainty estimate for 1P is only slightly larger than with 5P calibration. PMID:16756985

  20. 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.

  1. Liquid chromatographic determination of toxigenic secondary metabolites produced by Fusarium strains.

    PubMed

    Mateo, J J; Mateo, R; Hinojo, M J; Llorens, A; Jiménez, M

    2002-05-10

    Various liquid chromatographic methods used in the analysis of mycotoxins (zearalenone, trichothecenes and fumonisins) produced by Fusarium species were compared in this work. The results demonstrate the suitability of modern clean-up procedures employing multifunctional MycoSep and immunoaffinity columns although these methods are more expensive than conventional methodologies for clean-up. HPLC with both fluorescence and photodiode array detection is a suitable technique for the analysis of toxic secondary metabolites produced by Fusarium species; different derivatisation strategies have been studied to improve the sensitivity of the technique because of the low concentration of these metabolites in contaminated food. The utility of the proposed methodology was assessed in cereal cultures of various Fusarium strains.

  2. Reverse phase liquid chromatographic determination of aspartame in beverages and beverage mixes.

    PubMed

    Webb, N G; Beckman, D D

    1984-01-01

    A method is described for determining the artificial sweetener aspartame in beverages and beverage mixes by liquid chromatography. Aspartame is separated on a microC18 column, using a mobile phase of acetic acid, water, and isopropyl alcohol at pH 3.0 and UV detection at 254 nm. Beverages are filtered through 0.45 micron filters and injected directly into the chromatograph. Aspartame is eluted in approximately 7 min. Detection of aspartame is confirmed by a UV scan of the trapped peak. Aspartame is quantitated in the presence of other beverage additives such as saccharin, caffeine, sodium benzoate, artificial colors, and artificial flavors. Results are presented for spiked soda beverages, beverages from fruit-flavored mixes, instant tea, reconstituted presweetened drink mixes, and a powdered tabletop sweetener.

  3. Reverse-phase liquid chromatographic determination of benzoic and sorbic acids in foods.

    PubMed

    Bui, L V; Cooper, C

    1987-01-01

    An isocratic liquid chromatographic (LC) technique is described for the determination of benzoic acid and sorbic acid in foods such as beverages, fruits, seafood, vegetables, sauces, and dairy, bakery, and confectionery products. A C18 column is used with methanol-phosphate buffer (5 + 95) as mobile phase and 4-hydroxyacetanilide or 3,5-dinitrobenzoic acid as internal standard. Sample preparation is simple, rapid, and produces a sample extract that has a minimum effect on the column performance and life. Specificity of the method was checked against common food additives such as L-ascorbic acid, caffeine, artificial sweeteners (saccharin, cyclamate, aspartame), antioxidants (BHT, BHA) and artificial colors. Also described are 2 procedures for confirmation of the preservatives, using either redox reaction of sorbic acid with potassium permanganate or gas chromatography/mass spectrometry. Mean recoveries of 90-105% were obtained with a precision of 1-6% and a detection limit of 20 mg/kg for the 2 preservatives.

  4. High-performance liquid chromatographic separation of the enantiomers of unusual alpha-amino acid analogues.

    PubMed

    Péter, A; Olajos, E; Casimir, R; Tourwé, D; Broxterman, Q B; Kaptein, B; Armstrong, D W

    2000-02-25

    The direct and indirect stereochemical resolution of the enantiomers of ring- and alpha-methyl-substituted phenylalanines and phenylalanine amides was attempted by high-performance liquid chromatographic methods. The direct separation was carried out on two chiral stationary phases, the crown-ether-based Crownpak CR(+), and the teicoplanin-based Chirobiotic T, while the indirect resolution was performed by applying pre-column derivatization with 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl isothiocyanate (GITC) and Nalpha-(2,4-dinitro-5-fluorophenyl)-L-alanine amide (Marfey's reagent, FDAA). The Chirobiotic T column was efficient in the separation of ring- and alpha-methyl-substituted phenylalanine analogues, but was ineffective for the amides of these analogues. The Crownpak CR(+) column separated the ring-substituted phenylalanines and amides, whereas the alpha-methylated analogues were coeluted. Of the two indirect methods, GITC derivatization seemed more effective than FDAA derivatization.

  5. Thiopurine methyl transferase activity: new extraction conditions for high-performance liquid chromatographic assay.

    PubMed

    Ganiere-Monteil, C; Pineau, A; Kergueris, M F; Azoulay, C; Bourin, M

    1999-04-30

    A new liquid-liquid extraction is described for thiopurine methyl transferase (TPMT, EC 2.1.1.67) activity determination: the use of a pH 9.5 NH4Cl buffer solution, before adding the solvent mixture, allows more rapid extraction, avoiding a centrifugation step, and reduces the global cost of analysis. After the extraction step, 6-methylmercaptopurine, synthesised during the enzymatic reaction, is determined by a liquid chromatographic assay. Analytical performance of the assay was tested on spiked erythrocyte lysates. The linear concentration range was 5-250 ng ml(-1) (r> or =0.997, slope=1.497, intercept=-0.367). The recoveries were 82.8, 89.9 and 82.2% for 75, 125 and 225 ng ml(-1), respectively. The coefficients of variation were < or =6.1% for within-day assay (n=6) and < or =9.5% for between-day assay precision (n=6; 14 days). TPMT activity was determined in a French adult Caucasian population (7 =70). The results ranged from 7.8 to 27.8 nmol h(-1) ml(-1) packed red blood cells and the frequency distribution histogram is similar to that previously published.

  6. 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.

  7. 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.

  8. Quantum liquid with deconfined fractional excitations in three dimensions.

    PubMed

    Sikora, Olga; Pollmann, Frank; Shannon, Nic; Penc, Karlo; Fulde, Peter

    2009-12-11

    Excitations which carry "fractional" quantum numbers are known to exist in one dimension in polyacetylene, and in two dimensions, in the fractional quantum Hall effect. Fractional excitations have also been invoked to explain the breakdown of the conventional theory of metals in a wide range of three-dimensional materials. However, the existence of fractional excitations in three dimensions remains highly controversial. In this Letter we report direct numerical evidence for the existence of an extended quantum liquid phase supporting fractional excitations in a concrete, three-dimensional microscopic model-the quantum dimer model on a diamond lattice. We demonstrate explicitly that the energy cost of separating fractional monomer excitations vanishes in this liquid phase, and that its energy spectrum matches that of the Coulomb phase in (3+1)-dimensional quantum electrodynamics.

  9. 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.

  10. Liquid chromatographic enantioseparation of aryl alpha-amino ketones on a crown ether-based chiral stationary phase.

    PubMed

    Ho Hyun, Myung; Tan, Guanghui; Cho, Yoon Jae

    2005-04-01

    A liquid chromatographic chiral stationary phase based on (3,3'-diphenyl-1,1'-binaphthyl)-20-crown-6 covalently bonded to silica gel was applied in the resolution of aryl alpha-amino ketones including cathinone, the main psychoactive alkaloid found in the leaves of the khat plant. The resolution was excellent, the separation factors ranging between 1.72 and 8.58 and the resolution factors (R(S)) ranging between 2.60 and 11.10. The chromatographic resolution behaviour was dependent on the type and the content of organic and acidic modifiers and the ammonium acetate concentration in aqueous mobile phase and the column temperature.

  11. Fractionalized spin-wave continuum in kagome spin liquids

    NASA Astrophysics Data System (ADS)

    Mei, Jia-Wei; Wen, Xiao-Gang

    Motivated by spin-wave continuum (SWC) observed in recent neutron scattering experiments in Herbertsmithite, we use Gutzwiller-projected wave functions to study dynamic spin structure factor S (q , ω) of spin liquid states on the kagome lattice. Spin-1 excited states in spin liquids are represented by Gutzwiller-projected two-spinon excited wave functions. We investigate three different spin liquid candidates, spinon Fermi-surface spin liquid (FSL), Dirac spin liquid (DSL) and random-flux spin liquid (RSL). FSL and RSL have low energy peaks in S (q , ω) at K points in the extended magnetic Brillouin zone, in contrast to experiments where low energy peaks are found at M points. There is no obviuos contradiction between DSL and neutron scattering measurements. Besides a fractionalized spin (i.e. spin-1/2), spinons in DSL carry a fractionalized crystal momentum which is potentially detectable in SWC in the neutron scattering measurements.

  12. 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.

  13. Ionic liquids in chromatographic and electrophoretic techniques: toward additional improvements in the separation of natural compounds

    PubMed Central

    Freire, Carmen S. R.; Coutinho, João A. P.; Silvestre, Armando J. D.; Freire, Mara G.

    2016-01-01

    Due to their unique properties, in recent years, ionic liquids (ILs) have been largely investigated in the field of analytical chemistry. Particularly during the last sixteen years, they have been successfully applied in the chromatographic and electrophoretic analysis of value-added compounds extracted from biomass. Considering the growing interest in the use of ILs in this field, this critical review provides a comprehensive overview on the improvements achieved using ILs as constituents of mobile or stationary phases in analytical techniques, namely in capillary electrophoresis and its different modes, in high performance liquid chromatography, and in gas chromatography, for the separation and analysis of natural compounds. The impact of the IL chemical structure and the influence of secondary parameters, such as the IL concentration, temperature, pH, voltage and analysis time (when applied), are also critically addressed regarding the achieved separation improvements. Major conclusions on the role of ILs in the separation mechanisms and the performance of these techniques in terms of efficiency, resolution and selectivity are provided. Based on a critical analysis of all published results, some target-oriented ILs are suggested. Finally, current drawbacks and future challenges in the field are highlighted. In particular, the design and use of more benign and effective ILs as well as the development of integrated (and thus more sustainable) extraction–separation processes using IL aqueous solutions are suggested within a green chemistry perspective. PMID:27667965

  14. Ionic liquids in chromatographic and electrophoretic techniques: toward additional improvements in the separation of natural compounds

    PubMed Central

    Freire, Carmen S. R.; Coutinho, João A. P.; Silvestre, Armando J. D.; Freire, Mara G.

    2016-01-01

    Due to their unique properties, in recent years, ionic liquids (ILs) have been largely investigated in the field of analytical chemistry. Particularly during the last sixteen years, they have been successfully applied in the chromatographic and electrophoretic analysis of value-added compounds extracted from biomass. Considering the growing interest in the use of ILs in this field, this critical review provides a comprehensive overview on the improvements achieved using ILs as constituents of mobile or stationary phases in analytical techniques, namely in capillary electrophoresis and its different modes, in high performance liquid chromatography, and in gas chromatography, for the separation and analysis of natural compounds. The impact of the IL chemical structure and the influence of secondary parameters, such as the IL concentration, temperature, pH, voltage and analysis time (when applied), are also critically addressed regarding the achieved separation improvements. Major conclusions on the role of ILs in the separation mechanisms and the performance of these techniques in terms of efficiency, resolution and selectivity are provided. Based on a critical analysis of all published results, some target-oriented ILs are suggested. Finally, current drawbacks and future challenges in the field are highlighted. In particular, the design and use of more benign and effective ILs as well as the development of integrated (and thus more sustainable) extraction–separation processes using IL aqueous solutions are suggested within a green chemistry perspective.

  15. 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.

  16. Micellar liquid chromatographic determination of arbutin and hydroquinone in medicinal plant extracts and commercial cosmetic products.

    PubMed

    Thogchai, W; Liawruangrath, B

    2013-06-01

    A simple micellar liquid chromatographic (MLC) procedure for simultaneous determination of arbutin and hydroquinone in medicinal plant extracts and commercial cosmetic products was proposed. This method was developed and validated. The chromatographic conditions were also optimized. All analyses were performed at room temperature in an isocratic mode, using a mixture of 1% (v/v) acetonitrile and 0.006 mol L⁻¹ Brij 35 (pH 6.0) as a mobile phase. The flow rate was set at 1.0 mL min⁻¹. The analytical column was a 150 × 3.9 mm Nova-Pak C-18 column. The effluent from the analytical column was monitored by UV detection at 280 nm. Under the optimum conditions, arbutin and hydroquinone could be determined within a concentration range of 2-50 μg mL⁻¹ of arbutin, and hydroquinone was obtained with the regression equations; y = 0.045x + 0.042 (r² = 0.9923) and y = 0.091x + 0.050 (r² = 0.9930) respectively. The limits of detection were found to be 0.51 μg mL⁻¹ and 0.37 μg mL⁻¹ for arbutin and hydroquinone respectively. The proposed MLC method was applied for the determination of arbutin and hydroquinone contents in medicinal plant extracts and commercial cosmetic products. This proposed MLC method is thus suitable for routine analysis of arbutin and hydroquinone in the pharmaceutical formulations, cosmetic products and raw medicinal plant extracts.

  17. [Scale-up of conical column with 10 degree opening angle as preparative liquid chromatographic column].

    PubMed

    Lu, Liejuan; Chen, Jie; Guan, Yafeng

    2009-05-01

    A preparative scale liquid chromatographic column with the conical shape of 10 degrees opening angle was constructed and evaluated. The column was designed with the inlet/outlet diameters of 54/27 mm, the column length of 150 mm and the column volume of 200 mL, and packed with the spherical C18 bonded silica with the particle size of 40-75 microm and the aperture of 11 nm. The mobile phase in the conical column showed a plug like flow profile and plug like chromatographic band shape. For naphthalene, the reduced plate height was about 2.11; the maximum sample load was 2.1 mg or 1.7 mL (10% reduction of plate number), which is 20%, 16% and 19% higher than that of cylindrical one of the same length and volume. As the injection mass increased from 2. 4 mg up to 12 mg, the resolution of ethyl paraben/butyl (R, ) reduced from 2. 14 down to 1.71, and the butyl paraben/naphthalene (Rs3) from 2.91 down to 2.52; the injection volume increased from 3 mL up to 19 mL, Rs2, reduced from 2.23 down to 1.28, and Rs3 from 2.95 down to 2.30, while the peaks were still in symmetric shape without tailing. This characteristic of the column shall benefit for the separation of trace components from matrix. This demonstrated the conical shaped preparative columns would have a broad practical applicability for obtaining pure compounds. PMID:19803133

  18. [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.

  19. [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

  20. Determination of melengestrol acetate in feedstuffs with liquid chromatographic preparatory column cleanup and quantitative analysis.

    PubMed

    Weigand, J L; Dille, D S

    1988-01-01

    Melengestrol acetate (MGA) is determined by liquid chromatography using a fraction from preparatory LC as a means of sample cleanup for feedstuffs, both dry and liquid. Dry ground feed is Soxhlet extracted with hexane and passed through a 2% deactivated alumina column for initial cleanup. The eluate is evaporated, redissolved in methanol, filtered, and injected onto a preparatory LC column. The fraction containing MGA is separated from the remaining matrix, evaporated to dryness, dissolved in methanol, and quantitated by LC analysis. Liquid supplements are extracted in methanol, and the extract is evaporated to near dryness. The residue is diluted with water, extracted with chloroform, passed through sodium sulfate, and evaporated to dryness. The remaining sample is dissolved in methanol prior to preparative LC and quantitative LC. Recoveries for 2 laboratory-fortified commercial feeds, one dry and one liquid, containing 0.39 and 0.40 mg/lb, were 98.3% +/- 4.4 and 95.8% +/- 4.3, respectively. Results compare favorably with existing methods. Up to a 4-fold time savings was realized by this method without automation.

  1. pH-dependence of single-protein adsorption and diffusion at a liquid chromatographic interface.

    PubMed

    Kisley, Lydia; Poongavanam, Mohan-Vivekanandan; Kourentzi, Katerina; Willson, Richard C; Landes, Christy F

    2016-02-01

    pH is a common mobile phase variable used to control protein separations due to the tunable nature of amino acid and adsorbent charge. Like other column variables such as column density and ligand loading density, pH is usually optimized empirically. Single-molecule spectroscopy extracts molecular-scale data to provide a framework for mechanistic optimization of pH. The adsorption and diffusion of a model globular protein, α-lactalbumin, was studied by single-molecule microscopy at a silica-aqueous interface analogous to aqueous normal phase and hydrophilic interaction chromatography and capillary electrophoresis interfaces at varied pH. Electrostatic repulsion resulting in free diffusion was observed at pH above the isoelectric point of the protein. In contrast, at low pH strong adsorption and surface diffusion with either no (D ∼ 0.01 μm(2) /s) or translational (D ∼ 0.3 μm(2) /s) motion was observed where the protein likely interacted with the surface through electrostatic, hydrophobic, and hydrogen bonding forces. The fraction of proteins immobilized could be increased by lowering the pH. These results show that retention of proteins at the silica interface cannot be viewed solely as an adsorption/desorption process and that the type of surface diffusion, which ultimately leads to ensemble chromatographic separations, can be controlled by tuning long-range electrostatic and short-range hydrophobic and hydrogen bonding forces with pH.

  2. 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

  3. Chromatographic molecular weight measurements for heparin, its fragments and fractions, and other glycosaminoglycans.

    PubMed

    Mulloy, Barbara; Hogwood, John

    2015-01-01

    Glycosaminoglycan samples are usually polydisperse, consisting of molecules with differing length and differing sequence. Methods for measuring the molecular weight of heparin have been developed to assure the quality and consistency of heparin products for medicinal use, and these methods can be applied in other laboratory contexts. In the method described here, high-performance gel permeation chromatography is calibrated using appropriate heparin molecular weight markers or a single broad standard calibrant, and used to characterize the molecular weight distribution of polydisperse samples or the peak molecular weight of monodisperse, or approximately monodisperse, heparin fractions. The same technology can be adapted for use with other glycosaminoglycans.

  4. 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.

  5. Liquid chromatographic determination of free glutamic acid in soup, meat product, and Chinese food: interlaboratory study.

    PubMed

    Beljaars, P R; van Dijk, R; Bisschop, E; Spiegelenberg, W M

    1996-01-01

    An interlaboratory study of the liquid chromatographic (LC) determination of free glutamic acid in soup, meat product, and Chinese food was performed. Homogenized food samples were extracted with hot water, filtered, and diluted. Aliquot portions were treated with N,N-dimethyl-2-mer-capto-ethyl-ammonium chloride (DMMAC) and o-phtaldialdehyde (OPA) to convert glutamic acid to a stable fluorescent complex. After LC separation on a reversed-phase C18 column with acetonitrile-phosphate buffer (pH 7.0)-water (80 + 180 + 740, v/v) as mobile phase, glutamic acid peaks were measured fluorometrically (excitation, 340 nm, and emission, 389 and/or 440 nm). Homocysteic acid was used as internal standard. Twelve samples (6 blind duplicates) containing about 0.3-1.3% (w/w) of glutamic acid were analyzed singly by 12 laboratories. Results from one participant were excluded. Repeatability relative standard deviations (RSDr) varied from 1.3 to 4.5%, and reproducibility relative standard deviations (RSDR) ranged from 4.1 to 7.1%. Average recovery of glutamic acid determined at 6 levels was 101.5% (range, 98-106%).

  6. Computer monitoring, capture and analysis of gas/liquid chromatograph traces.

    PubMed

    Bulleid, N; Schofield, J

    1986-12-01

    The work described here is effectively the computerization of a gas/liquid chromatograph of the pen recorder type using a BBC microcomputer. The output from the g.l.c. can be captured by the computer in accordance with a series of parameters. The sampling rate can be altered, as can an averaging facility to reduce noise, and a threshold level to eliminate the storage of irrelevant and space-consuming data. The unprocessed readings are initially stored on the computer's floppy disk, then later retrieved and cut into smaller sections to allow maximum resolution for on-screen analysis. In the main analysis stage of the system all processing is shown graphically on the computer monitor at all stages. The principal steps in analysis involve the mathematical modelling and elimination of the solvent peak, the fixing of the retention time for each subsequent peak and its disentangling from any following peaks, and finally the calculation of the area under each individual peak. Several alternative methods are made available for disentangling peaks, which can be tried successively on a single peak then each printed out with comments for comparison later. All readings and results in table form and screen dumps of all trace images are available via a dot matrix printer.

  7. Liquid chromatographic determination of histamine in fish, sauerkraut, and wine: interlaboratory study.

    PubMed

    Beljaars, P R; Van Dijk, R; Jonker, K M; Schout, L J

    1998-01-01

    An interlaboratory study of the liquid chromatographic (LC) determination of histamine in fish, sauerkraut, and wine was conducted. Diminuted and homogenized samples were suspended in water followed by clarification of extracts with perchloric acid, filtration, and dilution with water. After LC separation on a reversed-phase C18 column with phosphate buffer (pH 3.0)--acetonitrile (875 + 125, v/v) as mobile phase, histamine was measured fluorometrically (excitation, 340 nm; emission, 455 nm) in samples and standards after postcolumn derivatization with o-phthaldialdehyde (OPA). Fourteen samples (including 6 blind duplicates and 1 split level) containing histamine at about 10-400 mg/kg or mg/L were analyzed singly according to the proposed procedure by 11 laboratories. Results from one participant were excluded from statistical analysis. For all samples analyzed, repeatability relative standard deviations varied from 2.1 to 5.6%, and reproducibility relative standard deviations ranged from 2.2 to 7.1%. Averaged recoveries of histamine for this concentration range varied from 94 to 100%.

  8. 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.

  9. Liquid chromatographic and ultraviolet spectrophotometric determination of bevantolol and hydrochlorothiazide in feeds.

    PubMed

    Spurlock, C H; Schneider, H G

    1984-01-01

    Separate assay methods have been developed for the 2 components of an 80 + 20 drug blend of bevantolol and hydrochlorothiazide (HCT) in admixtures with animal feed. Drug/diet admixtures are extracted with methanol for reverse phase ion-pair liquid chromatographic (LC) assay of bevantolol, and with acetonitrile for ultraviolet spectrophotometric assay of HCT. Bevantolol, a cardioselective beta blocker, is separated from soluble feed components with an RP-18 column, using methanol-water-acetic acid (60 + 40 + 1) containing 0. 005M octane-sulfonic acid, sodium salt, as ion-pairing reagent. HCT is determined spectrophotometrically in acetonitrile extracts, using a suitable blank extract as reference. Average recovery of HCT from an admixture of 0.5 mg blend/g diet is 94.5% +/- 4.3 RSD and at 2.0 mg/g, 101.5% +/- 3.5 RSD. Bevantolol recovery from the same admixtures is 101.8% +/- 2.7 RSD and 99.0% +/- 3.5 RSD, respectively, using the method as described.

  10. Micellar Liquid Chromatographic Determination of Carbaryl and 1-Naphthol in Water, Soil, and Vegetables

    PubMed Central

    Chin-Chen, Mei-Liang; Rambla-Alegre, Maria; Durgbanshi, Abhilasha; Bose, Devasish; Mourya, Sandeep K.; Esteve-Romero, Josep; Carda-Broch, Samuel

    2012-01-01

    A liquid chromatographic procedure has been developed for the determination of carbaryl, a phenyl-N-methylcarbamate, and its main metabolite 1-naphthol, using a C18 column (250 mm  ×  4.6 mm) with a micellar mobile phase and fluorescence detection at maximum excitation/emission wavelengths of 225/333 nm, respectively. In the optimization step, surfactants sodium dodecyl sulphate (SDS), Brij-35 and N-cetylpyridinium chloride monohydrate, and organic solvents propanol, butanol, and pentanol were considered. The selected mobile phase was 0.15 M SDS-6% (v/v)-pentanol-0.01 M NaH2PO4 buffered at pH 3. Validation studies, according to the ICH Tripartite Guideline, included linearity (r > 0.999), limit of detection (5 and 18 ng mL−1, for carbaryl and 1-naphthol, resp.), and limit of quantification (15 and 50 ng mL−1, for carbaryl and 1-naphthol, resp.), with intra- and interday precisions below 1%, and robustness parameters below 3%. The results show that the procedure was adequate for the routine analysis of these two compounds in water, soil, and vegetables samples. PMID:22505922

  11. 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

  12. Peak distortion in the column liquid chromatographic determination of omeprazole dissolved in borax buffer.

    PubMed

    Arvidsson, T; Collijn, E; Tivert, A M; Rosén, L

    1991-11-22

    Injection of a sample containing omeprazole dissolved in borax buffer (pH 9.2) into a reversed-phase liquid chromatographic system consisting of a mixture of acetonitrile and phosphate buffer (pH 7.6) as the mobile phase and a C18 surface-modified silica as the solid phase resulted under special conditions in split peaks of omeprazole. The degree of peak split and the retention time of omeprazole varied with the concentration of borax in the sample solution and the ionic strength of the mobile phase buffer as well as with the column used. Borax is eluted from the column in a broad zone starting from the void volume of the column. The retention is probably due to the presence of polyborate ions. The size of the zone varies with the concentration of borax in the sample injected. In the borax zone the pH is increased compared with the pH of the mobile phase, and when omeprazole (a weak acid) is co-eluting in the borax zone its retention is affected. In the front part and in the back part of the borax zone, pH gradients are formed, and these gradients can induce the peak splitting. When the dissolving medium is changed to a phosphate buffer or an ammonium buffer at pH 9 no peak distortion of omeprazole is observed.

  13. 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.

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

    PubMed

    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.

  15. Automated two-dimensional liquid chromatographic system for mapping proteins in highly complex mixtures.

    PubMed

    Isobe, T; Uchida, K; Taoka, M; Shinkai, F; Manabe, T; Okuyama, T

    1991-12-27

    An automated two-dimensional liquid chromatographic system was developed for systematic protein separations which could serve for analytical mapping and preparative separations of proteins. The system applies the principles of the column-switching technique, and consists of two different columns connected in tandem through an electrical column switching valve, two pumping systems to operate each column independently and a system controller to perform sequential chromatography on the two columns. A protein mixture is applied to the first-dimensional anion-exchange column and is separated by stepwise elution with an increasing sodium chloride concentration. The eluent is introduced directly to the second-dimensional reversed-phase column, and is further separated by gradient elution with an increasing acetonitrile concentration. The two elution stages are synchronized by a computer program. By this system, very complex protein mixtures such as crude cerebellar extracts were resolved reproducibly into ca. 200 peaks within 12 h. The method can be used for the total analysis of proteins in various tissues and cells without complicated premanupulation of samples, and allows the simultaneous analysis of a protein isolated by chromatography. The isolated protein is most suitable for use in the strategy of protein and gene sequence analysis.

  16. Isocratic liquid chromatographic determination of theophylline, acetaminophen, chloramphenicol, caffeine, anticonvulsants, and barbiturates in serum.

    PubMed

    Meatherall, R; Ford, D

    1988-01-01

    An isocratic reverse-phase high-performance liquid chromatographic system is described for resolving theophylline, acetaminophen, caffeine, chloramphenicol, ethosuximide, primidone, phenobarbital, phenytoin, and carbamazepine within 7 min. A procedure for routinely measuring these drugs in serum is validated and has been extended to include the quantification of N-desmethylmethsuximide, barbital, amobarbital, secobarbital, pentobarbital, mephobarbital, and thiopental. A 250 x 4.6 mm column packed with trimethylsilyl (C-1)-coated 5-microns particles is used. The mobile phase is phosphate buffer (10 mmol/L, pH 6.3):methanol:acetonitrile, 65:17.5:17.5. A common solvent extraction procedure is used for all of these drugs. The extractant is chloroform:isopropanol (95:5), containing three internal standards: 3-isobutyl-l-methylxanthine (IMX), tolybarb, and methsuximide. Theophylline, acetaminophen, caffeine, and chloramphenicol are quantified at 273 nm with IMX as the internal standard. With two exceptions, the rest of the drugs are quantified at 204 nm using tolybarb as the internal standard; ethosuximide is quantified at 204 nm using methsuximide as the internal standard, and thiopental is quantified at 285 nm using IMX as the internal standard.

  17. 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%).

  18. 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

  19. 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

  20. 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

  1. A high-performance liquid chromatographic assay for clindamycin phosphate and its principal degradation product in bulk drug and formulations.

    PubMed

    Munson, J W; Kubiak, E J

    1985-01-01

    A high-performance liquid chromatography method has been developed for the analysis of clindamycin phosphate and clindamycin, the principal degradation product. The method is quantitative, precise and is able to separate a variety of closely related molecules. The method has been applied to bulk drug, topical and sterile solutions, and experimental cream, lotion and gel formulations. The method gives results that are in good agreement with the official gas chromatographic method but is much less time-consuming.

  2. 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...

  3. 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.

  4. Retention Projection Enables Accurate Calculation of Liquid Chromatographic Retention Times Across Labs and Methods

    PubMed Central

    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.

    2015-01-01

    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

  5. [High performance liquid chromatographic determination of reducing sugars in fruit juices with laser resonance Raman detection].

    PubMed

    Ding, M; Koizumi, H; Suzuki, Y

    1997-07-01

    A liquid chromatographic method using semi-microcolumn separation combined with laser resonance Raman detection was developed for the determination of monosaccharides in fruit juices. Reducing sugars (galactose, glucose, mannose, arabinose, xylose and ribose) were derivatized with 4-dimethylaminoazobenzene-4'-sulfonyl (DABSYL) hydrazine. The derivatives of the monosaccharides exhibited strong resonance Raman scattering at 1136 cm(-1) when Ar+ laser emission line 488.0 nm was used. A semi-microcolumn Inertsil ODS-2 (250 mm x 1.5 mm i.d.) was used to the separation of the monosaccharide derivatives. The saccharides eluted within 25 min. However the excess DABSYL hydrazine was retained strongly with a retention time of about 60 min. In order to reduce the longer analysis time, the excess DABSYL hydrazine was removed by adding glyoxylic acid and then Na2CO3 aqueous solution when the derivation reaction was finished. As a result, the analysis time was reduced to about a half of its initial run time. The sensitivity of resonance Raman detection greater two orders of magnitude than refractive index (RI) detection. The detection limit of glucose is 10 ng (5.5 pmol). The high selectivity of Raman detection came from the facts that only the interested compounds in a given sample was derived with the Raman labeling reagent and that only the characteristic Raman bands of the derivatives were selectively detected. In this work, in spite of the coexisting large quantities of organic acids in fruit juice, the determined values of glucose agreed well with those obtained by RI detection without any derivatization procedure.

  6. Simple automated liquid chromatographic system for splitless nano column gradient separations.

    PubMed

    Sesták, Jozef; Duša, Filip; Moravcová, Dana; Kahle, Vladislav

    2013-02-01

    A simple splitless gradient liquid chromatographic system for micro and nano column separations has been assembled and tested. It consists of an OEM programmable syringe pump equipped with a glass microsyringe and ten-port selector valve. Gradient of mobile phase was created in the syringe barrel due to turbulent mixing. Capability of suggested system to create various gradient profiles was verified using 50-μl, 100-μl, and 250-μl glass syringes. Acetone, thiourea, and uracil were tested as gradient markers and finally, uracil was proved to be an excellent way of water-acetonitrile gradient tracing. It was found that up to 80% of the total syringe volume is available as a linear gradient section. In context to micro and nano column chromatography, the best results were obtained using the 100-μl syringe. Separations were performed on the capillary monolithic column Chromolith CapRod RP-18e (150mm×0.1mm) and system performance was evaluated using a test mixture of six alkylphenones as well as tryptic digest of bovine serum albumin. Results proved that suggested system is able to create uniform gradients with high repeatability of retention times of test solutes (RSD<0.3%). Repeatability of injection of sample volumes in the range of 0.1-3μl was evaluated using on-column preconcentration technique which means that sample was diluted in mobile phase of low eluting strength. Repeatability of the peak areas was measured and statistically evaluated (RSD<5%).

  7. 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.

  8. Analysis of pharmaceutical dosage forms for oxfendazole: I. Reverse phase liquid chromatographic determination of oxfendazole in swine premix.

    PubMed

    Fleitman, J; Neu, D; Visor, G

    1986-01-01

    A reverse phase liquid chromatographic (LC) procedure is described for quantitating oxfendazole (2-(methoxycarbonylamino)-5-phenylsulfinylbenzimidazole] in swine premix. Sample preparation consists of extracting oxfendazole with an acetone-methanol mixture. An aliquot of the extract is then centrifuged to separate undissolved premix excipients. Internal standard is added to the supernate and the sample is further diluted with water-acetonitrile-phosphoric acid (80 + 20 + 1). Oxfendazole is quantitatively determined using a Partisil-5-ODS-3 column with acetonitrile-0.01 M phosphate buffer (pH 6.0) as the mobile phase. The method is stability specific and yields a mean recovery of 101.1 +/- 0.4% for the 1.35% premix formulation. The dependence of chromatographic performance characteristics on mobile phase organic content, pH, and buffer concentration is also reported.

  9. Analysis of pharmaceutical dosage forms for oxfendazole: II. Simultaneous liquid chromatographic determination of oxfendazole and trichlorfon in equine paste.

    PubMed

    Fleitman, J; Neu, D; Benjamin, E

    1986-01-01

    A reverse phase liquid chromatographic procedure is described for the simultaneous determination of oxfendazole [2-(methoxycarbonylamino)-5-phenylsulfinylbenzimidazole] and trichlorfon [(2,2,2-trichloro-1-hydroxyethyl)phosphonic acid dimethyl ester] in equine paste. The sample is extracted by sonication in methanol. Insoluble excipients are removed by centrifugation and an aliquot plus internal standard are diluted with dilution solvent (water-acetonitrile-phosphoric acid, 80 + 20 + 1). The samples are filtered and injected onto a Partisil-5 ODS-3 column with acetonitrile-0.01 M phosphate buffer pH 6.0 (20 + 80) as mobile phase. Method specificity is confirmed using an absorbance rationing technique. The method yields mean recoveries of 100.9 and 100.0% for trichlorfon and oxfendazole, respectively. Dependence of chromatographic performance characteristics on mobile phase organic content, pH, and buffer concentration is also reported.

  10. Development of a liquid chromatographic assay for an anti-HIV tablet containing lamivudine, zidovudine and TMC278.HCL.

    PubMed

    Pendela, M; Van Gyseghem, E; Van den Mooter, G; Baert, L; Rosier, J; Hoogmartens, J; Adams, E

    2009-02-20

    A liquid chromatographic method was developed to analyse a tablet containing three anti-human immunodeficiency virus (HIV) compounds: lamivudine, zidovudine and a compound with the code name TMC278.HCl. Due to the presence of UV absorbing chromophores in the three active components, a single LC method with UV detection was developed. A Hypersil BDS C(18) column was used as stationary phase and the assay was performed with gradient elution using mobile phases containing acetonitrile, 0.2M potassium dihydrogen phosphate and water. The sample pretreatment is performed by treating the formulation with dimethyl sulfoxide-water (1:1) followed by filtration. After method development, the influence of the different chromatographic parameters on the separation, the interference of other active compounds and excipients, the repeatability and the linearity were investigated. The method was shown to be robust, selective, linear and repeatable. Finally, the content of the compounds in the tablet was determined.

  11. A validated stability indicating high performance reverse phase liquid chromatographic method for the determination of cilostazol in bulk drug substance.

    PubMed

    Jadhav, A S; Pathare, D B; Shingare, M S

    2007-02-01

    A simple, rapid and accurate reverse phase high-performance liquid chromatographic (RP-HPLC) method was developed for the quantitative determination of cilostazol. The developed method is also applicable for the related substance determination in bulk drugs. The chromatographic separation was achieved on reversed-phase C-18 column. Eluents were monitored on photo-diode array detector at a wavelength of 210 nm using a mixture (50:50) of water and acetonitrile. Solution concentrations were quantified by external calibration. In the developed HPLC method, resolution between cilostazol and its potential impurities, namely Imp-A, Imp-B, and Imp-C were found greater than two. The drug was subjected to stress condition of hydrolysis, oxidation, photolysis and thermal degradation. Considerable degradation was found to occur in alkaline medium stress condition. The developed RP-HPLC method was validated with respect to linearity, accuracy, precision, stability of analytical solutions, and robustness.

  12. The Application of Chemical Derivatization in Forensic Drug Chemistry for Gas and High-Performance Liquid Chromatographic Methods of Analysis.

    PubMed

    Moore, J M

    1990-12-01

    The analyses of solid-dosage forensic drug samples can be enhanced by chemical derivatization followed by gas chromatography or high-performance liquid chromatography. Using these techniques permits improved detection and chromatography of some illicit drugs and their manufacturing by-products. This review focuses on the use of chemical derivatization in conjunction with gas chromatography-flame ionization detection, gas chromatography-electron capture detection, gas chromatography-mass spectrometry, high-performance liquid chromatography-ultraviolet detection and high-performance liquid chromatography-fluorescence detection in the analysis of illicit drug samples. These drugs include the amphetamines, barbiturates, cannabis, fentanyls, opium, and hallucinogens. Discussion on sensitivity enhancement and determination of enantiomeric composition using gas chromatography and high-performance liquid chromatography is included. An entire section is devoted to the chemical derivatization and chromatographic analyses of manufacturing by-products found in illicit amphetamine and methamphetamine, heroin, and cocaine samples. This review also includes a section that describes practical elements and experimental design associated with chemical derivatization-chromatographic analyses..

  13. 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

  14. 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.

  15. 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.

  16. High-yield resin fractionation using a liquid/liquid centrifuge

    NASA Astrophysics Data System (ADS)

    Wanat, Stan F.; Rahman, M. D.; Narasimhan, Balaji; McKenzie, Douglas S.; Cook, Michelle M.

    2000-06-01

    Resins used in photoresist manufacturing are often relatively expensive once processing steps (fractionation e.g.) and yield losses are factored into the net cost. We have previously reported on the merits of using an economically more attractive fractionation process using a liquid/liquid centrifuge. Further refinements of this method indicate that waste streams could be reduced by recycling the extractant phase and that lower molecular weight fractions removed from the starting resin might be used in making other resist ingredients [speed enhancers, photoactive compound (PAC) backbones e.g.]. Both of these improvements would reduce the overall manufacturing costs of making resist raw materials and the final products made with them.

  17. Comparison of two gas-liquid chromatograph columns for the analysis of fatty acids in ruminant meat.

    PubMed

    Alves, Susana P; Bessa, Rui J B

    2009-06-26

    Two gas-liquid chromatograph capillary columns for the analysis of fatty acids (FA) in ruminant fat are compared. Those columns are the CP-Sil 88 of 100 m long with a highly polar stationary phase and the Omegawax 250 of 30 m long with a stationary phase of intermediate polarity. Fatty acid methyl ester (FAME) patterns of branched-chain, cis and trans octadecenoate isomers, as well as conjugated and non-conjugated 18:2 and 18:3 isomers are fairly different between columns, even though most of the FAME could be separated on either column. However, the CP-Sil 88 showed better resolution of 18:1 isomers than Omegawax 250. The analysis of 96 samples of ruminant meat fat in both chromatographic systems showed that averages obtained for total FA content and for most of the individual FA did not differ between columns. Moreover, regression analysis of Omegawax and CP-Sil 88 data is highly correlated. Quantitative differences between chromatographic systems were detected for samples containing more than 66 mg fatty acids per gram of muscle dry matter.

  18. High-performance liquid chromatographic determination with photodiode array detection of ellagic acid in fresh and processed fruits.

    PubMed

    Amakura, Y; Okada, M; Tsuji, S; Tonogai, Y

    2000-10-27

    A high-performance liquid chromatographic (HPLC) procedure based on an isocratic elution with photodiode array detection has been developed for a simple and rapid determination of ellagic acid (EA) in fresh and processed fruits. The homogenized sample was refluxed with methanol and then the extract was refined using a solid-phase cartridge before HPLC. We analyzed EA in 40 kinds of fresh fruits and 11 kinds of processed fruits by the developed method. EA was found in several berries, fueijoa, pineapple and pomegranate. This is the first occurrence of the detection of EA in bayberry, fueijoa and pineapple.

  19. High-performance liquid chromatographic analysis of neomycin in petrolatum-based ointments and in veterinary formulations.

    PubMed

    Binns, R B; Tsuji, K

    1984-01-01

    A high-performance liquid chromatographic (HPLC) method has been developed for the assay of neomycin in petrolatum-based ophthalmic and topical ointments and in veterinary formulations. Neomycin assay interferences from drugs, such as bacitracin and polymyxin B and inactive components, e.g. wax, were eliminated by a methanol wash and/or a partitioning method. The extracted neomycin was derivatized with 2,4-dinitrofluorobenzene followed by normal-phase HPLC with detection at 254 nm. The average recovery of neomycin from spiked samples was approximately 100% with a relative standard deviation of less than 1%.

  20. 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%.

  1. Real-space imaging of fractional quantum Hall liquids.

    PubMed

    Hayakawa, Junichiro; Muraki, Koji; Yusa, Go

    2013-01-01

    Electrons in semiconductors usually behave like a gas--as independent particles. However, when confined to two dimensions under a perpendicular magnetic field at low temperatures, they condense into an incompressible quantum liquid. This phenomenon, known as the fractional quantum Hall (FQH) effect, is a quantum-mechanical manifestation of the macroscopic behaviour of correlated electrons that arises when the Landau-level filling factor is a rational fraction. However, the diverse microscopic interactions responsible for its emergence have been hidden by its universality and macroscopic nature. Here, we report real-space imaging of FQH liquids, achieved with polarization-sensitive scanning optical microscopy using trions (charged excitons) as a local probe for electron spin polarization. When the FQH ground state is spin-polarized, the triplet/singlet intensity map exhibits a spatial pattern that mirrors the intrinsic disorder potential, which is interpreted as a mapping of compressible and incompressible electron liquids. In contrast, when FQH ground states with different spin polarization coexist, domain structures with spontaneous quasi-long-range order emerge, which can be reproduced remarkably well from the disorder patterns using a two-dimensional random-field Ising model. Our results constitute the first reported real-space observation of quantum liquids in a class of broken symmetry state known as the quantum Hall ferromagnet.

  2. 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 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 (53)Cr/(52)Cr (μ(53)Cr* of 5.2 ppm) and (54)Cr/(52)Cr (μ(54)Cr* 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 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

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. Fractionalized Fermi liquid in a Kondo-Heisenberg model

    NASA Astrophysics Data System (ADS)

    Tsvelik, A. M.

    2016-10-01

    The Kondo-Heisenberg model is used as a controllable tool to demonstrate the existence of a peculiar metallic state with unbroken translational symmetry where the Fermi surface volume is not controlled by the total electron density. I use a nonperturbative approach where the strongest interactions are taken into account by means of exact solution, and corrections are controllable. In agreement with the general requirements formulated by T. Senthil et al. [Phys. Rev. Lett. 90, 216403 (2003), 10.1103/PhysRevLett.90.216403], the resulting metallic state represents a fractionalized Fermi liquid where well defined quasiparticles coexist with gapped fractionalized collective excitations. The system undergoes a phase transition to an ordered phase (charge density wave or superconducting), at the transition temperature which is parametrically small in comparison to the quasiparticle Fermi energy.

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. [A simple preparation method of an electric heating apparatus for heating capillary chromatographic columns and its application in liquid chromatography-mass spectrometry system].

    PubMed

    Jin, Zuyao; Lü, Yayao; Zhou, Shanshan; Hao, Feiran; Fu, Bin; Ying, Wantao; Qian, Xiaohong; Zhang, Yangjun

    2015-06-01

    For deep coverage of proteome, especially in performing qualitative identification and quantitative analysis of low-abundance proteins, the most commonly used method is the application of a longer capillary chromatographic column or a capillary column packed with smaller particle sizes. However, this causes another problem, the very high back pressure which results in liquid leaks in some connection parts in a liquid chromatograph. To solve this problem, an electric heating apparatus was developed to raise the temperature of a capillary column for reducing its back pressure, which was further applied in a capillary high performance liquid chromatography-tandem mass spectrometry system (cHPLC-MS/MS), and evaluated in the terms of chromatographic column back pressure and chromatographic column efficiency using bovine serum albumin (BSA) tryptic digests and yeast tryptic digests, separately. The results showed that at the optimum current, our electric heating apparatus could reduce the column pressure of a capillary column packed with 3 µm packing materials by at least 50% during the separation of BSA tryptic digestion and yeast tryptic digestion, compared with that without electric heating. The column efficiency was also increased slightly. This suggested that the electric heating apparatus can significantly reduce the column pressure, which provides an efficient way to use capillary chromatographic columns packed with smaller sizes of particles at a lower pressure.

  17. 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.

  18. 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

  19. A high performance liquid chromatographic assay of Mefloquine in saliva after a single oral dose in healthy adult Africans

    PubMed Central

    2012-01-01

    Background Mefloquine-artesunate is a formulation of artemisinin based combination therapy (ACT) recommended by the World Health Organization and historically the first ACT used clinically. The use of ACT demands constant monitoring of therapeutic efficacies and drug levels, in order to ensure that optimum drug exposure is achieved and detect reduced susceptibility to these drugs. Quantification of anti-malarial drugs in biological fluids other than blood would provide a more readily applicable method of therapeutic drug monitoring in developing endemic countries. Efforts in this study were devoted to the development of a simple, field applicable, non-invasive method for assay of mefloquine in saliva. Methods A high performance liquid chromatographic method with UV detection at 220 nm for assaying mefloquine in saliva was developed and validated by comparing mefloquine concentrations in saliva and plasma samples from four healthy volunteers who received single oral dose of mefloquine. Verapamil was used as internal standard. Chromatographic separation was achieved using a Hypersil ODS column. Results Extraction recoveries of mefloquine in plasma or saliva were 76-86% or 83-93% respectively. Limit of quantification of mefloquine was 20 ng/ml. Agreement between salivary and plasma mefloquine concentrations was satisfactory (r = 0.88, p < 0.001). Saliva:plasma concentrations ratio was 0.42. Conclusion Disposition of mefloquine in saliva paralleled that in plasma, making salivary quantification of mefloquine potentially useful in therapeutic drug monitoring. PMID:22369125

  20. Development of a validated liquid chromatographic method for determination of related substances of telmisartan in bulk drugs and formulations.

    PubMed

    Rao, R Nageswara; Guru Prasad, K; Gangu Naidu, Ch; Maurya, Pawan K

    2011-11-01

    A simple and rapid reversed phase liquid chromatographic method for separation and determination of the related substances of telmisartan (TLM) was developed and validated. The chromatographic separation was achieved on Lichrospher RP-18 column (250 × 4.6 mm, 5 μm), using 20 mM ammonium acetate containing 0.1% (v/v) triethylamine (pH adjusted to 3.0 with trifluoroacetic acid) and acetonitrile as mobile phase at 25°C. The detection was performed at 254 nm. The method was validated and found to be robust, precise, specific and linear between 0.37 and 500 μg/mL. The limits of detection and quantification of telmisartan were 0.11 and 0.37 μg/mL, respectively. The method was successfully applied to quantify related substances and assay of TLM in bulk drugs and commercial tablets. The related substances relate to a novel synthetic route and different from those A-H impurities reported by European Pharmacopeia.

  1. 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

  2. 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

  3. High-performance liquid chromatographic separation of the enantiomers of organophosphorus pesticides on polysaccharide chiral stationary phases.

    PubMed

    Ellington, J J; Evans, J J; Prickett, K B; Champion, W L

    2001-09-14

    High-performance liquid chromatographic separation of the individual enantiomers of 12 organophosphorus pesticides (OPs) was obtained on polysaccharide enantioselective HPLC columns using alkane-alcohol mobile phase. The OP pesticides were crotoxyphos, dialifor, fonofos, fenamiphos, fensulfothion, isofenphos, malathion, methamidophos, profenofos, crufomate, prothiophos and trichloronate. The enantiomers of fenamiphos, fensulfothion, profenofos and crufomate were separated on CHIRALPAK AD; the enantiomers of fenamiphos were also separated on CHIRALPAK AS; the enantiomers of methamidophos, crufomate and trichloronate were separated on CHIRALCEL OD; the enantiomers of crotoxyphos, dialifor, fonofos, malathion, prothiophos and trichloronate were separated on CHIRALCEL OJ; and the enantiomers of isofenphos were separated on CHIRALCEL OG. Baseline or partial separation of the enantiomers of six of these OP pesticides was obtained on CHIRALCEL OJ. In continued method development, the separation of the enantiomers of the 12 OPs was investigated more extensively on CHIRALCEL OJ to determine whether the mobile phase composition, flow-rate and column temperature could be optimized to yield at least partial separation of the enantiomers. Chromatographic conditions were found that gave either baseline or near baseline separations of the enantiomers of the 12 OPs on the CHIRALCEL OJ column. PMID:11587332

  4. Pretreatment and fractionation of wheat straw using various ionic liquids.

    PubMed

    Lopes, André M da Costa; João, Karen G; Bogel-Łukasik, Ewa; Roseiro, Luísa B; Bogel-Łukasik, Rafał

    2013-08-21

    Pretreatment of lignocellulosic biomass with ionic liquids (ILs) is a promising and challenging process for an alternative method of biomass processing. The present work emphasizes the examination of wheat straw pretreatment using ILs, namely, 1-butyl-3-methylimidazolium hydrogensulfate ([bmim][HSO4]), 1-butyl-3-methylimidazolium thiocyanate ([bmim][SCN]), and 1-butyl-3-methylimidazolium dicyanamide ([bmim][N(CN)2]). Only [bmim][HSO4] was found to achieve a macroscopic complete dissolution of wheat straw during pretreatment. The fractionation process demonstrated to be dependent on the IL used. Using [bmim][SCN], a high-purity lignin-rich material was obtained. In contrast, [bmim][N(CN)2] was a good solvent to produce high-purity carbohydrate-rich fractions. When [bmim][HSO4] was used, a different behavior was observed, exhibiting similarities to an acid hydrolysis pretreatment, and no hemicellulose-rich material was recovered during fractionation. A capillary electrophoresis (CE) technique allowed for a better understanding of this phenomenon. Hydrolysis of carbohydrates was confirmed, although an extended degradation of monosaccharides to furfural and hydroxymethylfurfural (HMF) was observed.

  5. Stability-Indicating High-Performance Liquid Chromatographic Determination of Apixaban in the Presence of Degradation Products

    PubMed Central

    Prabhune, Swarup Suresh; Jaguste, Rajendra Shankar; Kondalkar, Prakash Laxman; Pradhan, Nitin Sharadchandra

    2014-01-01

    Abstract A simple, robust, and stability-indicating reversed-phase high-performance liquid chromatographic (HPLC) method for the analysis of apixaban and its related substances has been successfully developed. Chromatography was performed on a 250 mm × 4.6 mm, 5 μm C18 column with a gradient mixture of a phosphate buffer–methanol 60:40 (v/v) at 1.0 mL min-1. Ultraviolet detection of apixaban was at 220 nm. The method was validated for linearity, precision, repeatability, sensitivity, and selectivity. Selectivity was validated by subjecting apixaban solution to photolytic, acidic, basic, oxidative, and thermal degradation. The peaks from the degradation products did not interfere with that from apixaban. The method was used to quantify the related substances in apixaban in the bulk drug and can be used for routine quality control purposes. PMID:26171323

  6. Simultaneous high-performance liquid chromatographic determination of paracetamol, phenylephrine HCl, and chlorpheniramine maleate in pharmaceutical dosage forms.

    PubMed

    Senyuva, Hamide; Ozden, Tuncel

    2002-02-01

    A rapid, precise, and specific high-performance liquid chromatographic method is described for the simultaneous determination of paracetamol, phenylephrine HCI, and chlorpheniramine maleate in combined pharmaceutical dosage forms. The method involves the use of a microBondapak CN RP analytical column (125 A, 10 microm, 3.9 x 150 mm) at 22 degrees C as the stationary phase with the mixture of acetonitrile and phosphate buffer (pH 6.22, 78:22) as the mobile phase. Derivatization of the drugs is not required. The method is applied to commercial pediatric cough-cold syrups, tablets, and capsules marketed in Turkey. The relative standard deviation for 10 replicate measurements of each drug in the medicaments is always less than 2%.

  7. High-performance liquid chromatographic determination of oxolinic acid in the plasma of seabass (Dicentrarchus labrax) anaesthetized with 2-phenoxyethanol.

    PubMed

    Loussouarn, S; Pouliquen, H; Armand, F

    1997-09-26

    A high-performance liquid chromatographic (HPLC) method for the determination of oxolinic acid (OA) in the plasma of seabass (Dicentrarchus labrax) anaesthetized with 2-phenoxyethanol is described. The samples were extracted and cleaned up by a solid-phase extraction procedure using C18 extraction cartridges. After the eluent was evaporated, the dry residue was dissolved in 1/15 M phosphate buffer. OA was determined by using an isocratic HPLC method with UV detection at 340 nm. Seabass drug-free plasma samples were spiked with OA at 0.2, 1.0, 5.0 and 25.0 microg/ml. Validation of the method showed good precision and accuracy. The mean recovery was 92.2%, with a relative standard deviation lower than 5%. The quantification limit was 0.2 microg/ml. The method was tested on 300 plasma samples of OA-treated seabass.

  8. Liquid chromatographic determination of aspartame in dry beverage bases and sweetener tablets with confirmation by thin layer chromatography.

    PubMed

    Daniels, D H; Joe, F L; Warner, C R; Fazio, T

    1984-01-01

    A liquid chromatographic method is described for the determination of aspartame in dry beverage bases and sweetener tablets. The sample was mixed with the mobile phase, the pH was adjusted to within +/- 0.1 pH unit of the mobile phase, and the sample was diluted to volume with the mobile phase. The solution was filtered and a 10 microL aliquot was injected onto a C18 reverse phase column. Aspartame was quantitated with an ultraviolet detector. Recoveries of aspartame ranged from 94 to 111%. The dry beverage bases contained 5-13% aspartame and the sweetener tablets contained 19% aspartame. The presence of aspartame was confirmed by using thin layer chromatography.

  9. 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.

  10. 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.

  11. 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

  12. [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

  13. [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.

  14. 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

  15. Extraction of ranitidine and nizatidine with using imidazolium ionic liquids prior spectrophotometric and chromatographic detection.

    PubMed

    Kiszkiel, Ilona; Starczewska, Barbara; Leśniewska, Barbara; Późniak, Patrycja

    2015-03-15

    A new extraction medium was proposed for liquid-liquid extraction of the histamine H2 receptor antagonists ranitidine (RNT) and nizatidine (NZT). The ionic liquids with low vapor pressure and favorable solvating properties for a range of compounds such as 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6] and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C4mim][Tf2N] were tested for isolation of analytes. The extraction parameters of RNT and NZT, namely, amount of ionic liquid, pH of sample solution, shaking and centrifugation time were optimized. The isolation processes were performed with 1 mL of the ionic liquids. The extracted samples (pH values near 4) were shaken at 1750 rpm. The influence of interfering substances on the efficiency of extraction process was also studied. Methods for the histamine H2 receptor antagonists (ranitidine and nizatidine) determination after their separation using imidazolium ionic liquids by high performance liquid chromatography (HPLC) combined with UV spectrophotometry were developed. The application of ionic liquids in extraction step allows for selective isolation of analytes from aqueous matrices and their preconcentration. The above methods were applied to the determination of RNT and NZT in environmental samples (river water and wastewater after treatment).

  16. 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.

  17. 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

  18. A high-performance liquid chromatographic assay for the enantiomers of bevantolol in human plasma.

    PubMed

    Rose, S E; Randinitis, E J

    1991-06-01

    A method was developed and validated for the simultaneous analysis of (+)- and (-)-bevantolol in human plasma. The assay involves plasma protein precipitation, derivatization of racemic bevantolol to its diastereomeric thioureas with 2,3,4,5-tetra-o-acetyl-alpha-D-glucopyranosyl isothiocyanate, and solid-phase extraction of the diastereomers from 0.5 ml human plasma. Chromatographic separation was accomplished under isocratic conditions using a reversed-phase C-18 analytical column and mobile phase consisting of equal parts of 75 mM dibasic ammonium phosphate buffer (adjusted to pH 3.5 with phosphoric acid) and acetonitrile, with a detection wavelength of 220 nm. The absolute peak-height method was employed for quantitation. Retention times for the diastereomers of (+)- and (-)-bevantolol were 7.4 and 6.4 min, respectively. The method is suitable for the quantification of the enantiomers over a concentration range of 40 to 800 ng/ml per enantiomer.

  19. High performance liquid chromatographic procedure for the simultaneous determination of theophylline, caffeine, and phenobarbital in neonates.

    PubMed

    Soto-Otero, R; Mendez-Alvarez, E; Sierra-Marcuño, G

    1985-05-01

    A sensitive HPLC method is reported for the simultaneous determination of theophylline, caffeine, and phenobarbital in 100 microliters of plasma. After a single extraction of the drugs with chloroform/isopropanol (90 + 10 by volume) at low pH in the presence of an excess of ammonium sulphate they are resolved and quantified using a reversed-phase column (Spherisorb 5 ODS). The drugs are eluted with a binary-solvent gradient system (acetonitrile/phosphate buffer pH 4.6) at room temperature and monitored at 204 nm. Quantitation is based on peak-height ratio of analyte to interval standard (8-chlorotheophylline). Complete chromatographic resolution of all drugs is achieved within 15 min. The method is linear to 40 mg/l of theophylline and caffeine, and to 80 mg/l of phenobarbital. Numerous drugs and xanthine metabolites tested do not interfere.

  20. 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...

  1. Liquid Chromatographic Determination of Nitroanilines: An Experiment for the Quantitative Analysis Laboratory.

    ERIC Educational Resources Information Center

    Cantwell, Frederick F.; Brown, David W.

    1981-01-01

    Describes a three-hour liquid chromatography experiment involving rapid separation of colored compounds in glass columns packed with a nonpolar absorbent. Includes apparatus design, sample preparation, experimental procedures, and advantages for this determination. (SK)

  2. Two tools for applying chromatographic retention data to the mass-based identification of peptides during hydrogen/deuterium exchange experiments by nano-liquid chromatography/matrix-assisted laser desorption/ionization mass spectrometry.

    PubMed

    Gershon, P D

    2010-12-15

    Two tools are described for integrating LC elution position with mass-based data in hydrogen-deuterium exchange (HDX) experiments by nano-liquid chromatography/matrix-assisted laser desorption/ionization mass spectrometry (nanoLC/MALDI-MS, a novel approach to HDX-MS). The first of these, 'TOF2H-Z Comparator', highlights peptides in HDX experiments that are potentially misidentified on the basis of mass alone. The program first calculates normalized values for the organic solvent concentration responsible for the elution of ions in nanoLC/MALDI HDX experiments. It then allows the solvent gradients for the multiple experiments contributing to an MS/MS-confirmed peptic peptide library to be brought into mutual alignment by iteratively re-modeling variables among LC parameters such as gradient shape, solvent species, fraction duration and LC dead time. Finally, using the program, high-probability chromatographic outliers can be flagged within HDX experimental data. The role of the second tool, 'TOF2H-XIC Comparator', is to normalize the LC chromatograms corresponding to all deuteration timepoints of all HDX experiments of a project, to a common reference. Accurate normalization facilitates the verification of chromatographic consistency between all ions whose spectral segments contribute to particular deuterium uptake plots. Gradient normalization in this manner revealed chromatographic inconsistencies between ions whose masses were either indistinguishable or separated by precise isotopic increments.

  3. High-performance liquid chromatographic column packings with different particle sizes: chromatographic behavior for the quality analysis of HuanglianShangqing pill.

    PubMed

    Yang, Dongzhi; Li, Ying; Yang, Fangxiu; Du, Yan; Li, Yinjie; Zheng, Xiaoxiao; Tang, Daoquan

    2015-02-01

    The chromatographic separation of traditional Chinese medicines is still a highly challenging task in analytical science with respect to its hundreds and thousands of chemical compounds, while increase of separation efficiency can greatly improve the separation power of chromatographic column for traditional Chinese medicine. In this study, 13 bioactive components in HuanglianShangqing pill were selected as an index to optimize the separation conditions and evaluate the system suitability of three commercially available columns packed with 1.8, 3.5, and 5.0 μm particles. The chromatographic separations were obtained by the most appropriate Eclipse Plus C18 column (100 × 2.1 mm, 3.5 μm) within 45 min using gradient elution with aqueous-ammonium acetate (10 mmol/L, pH 5.0) and acetonitrile, at a flow rate of 0.3 mL/min and an operating temperature of 30°C. The quality of HuanglianShangqing pill was assessed through combining simultaneous quantification of 13 compounds with fingerprint analysis. For the qualitative analysis, mass spectrometry was used to confirm the 13 compounds. All the validation data conformed to the acceptable requirements. For the fingerprint analysis, 32 peaks were selected as the common peaks at 254 nm to evaluate the similarities among HuanglianShangqing pills obtained from ten manufacturers.

  4. Flash chromatography on cartridges for the separation of plant extracts: rules for the selection of chromatographic conditions and comparison with medium pressure liquid chromatography.

    PubMed

    Weber, Petra; Hamburger, Matthias; Schafroth, Nina; Potterat, Olivier

    2011-03-01

    Empirical rules for the selection of chromatographic conditions on flash chromatography cartridges were developed, with an emphasis on gradient mode. These rules were then tested with separation of extracts from important medicinal plants including Curcuma xanthorrhiza, Piper nigrum and Salvia milthiorrhiza. Sepacore® cartridges enabled a good separation of compounds with a broad range of polarity, as typically found in plant extracts. The chromatographic resolution remained, however, lower than that achieved on classical columns packed with material of smaller particle size. For poorly soluble extracts, solid introduction gave better results than liquid injection.

  5. 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)).

  6. Transition metal-induced degradation of a pharmaceutical compound in reversed-phase liquid chromatographic analysis.

    PubMed

    Wang, Qinggang; He, Brian Lingfeng; Zhang, Jin; Huang, Yande; Kleintop, Brent; Raglione, Thomas

    2015-01-01

    Drug degradation that occurs in HPLC analysis, during either sample preparation or chromatographic separation, can greatly impact method robustness and result accuracy. In this work, we report a case study of drug dimerization in HPLC analysis where proximate causes were attributed to either the LC columns or the HPLC instrument. Solution stress studies indicated that the same pseudo-dimeric degradants could also be formed rapidly when the compound was exposed to certain oxidative transition metal ions, such as Cu(II) and Fe(III). Two pseudo-dimeric degradants were isolated from transition metal stressed samples and their structures were elucidated. A degradation pathway was proposed, whereby the degradation was initiated through transition metal-induced single electron transfer oxidation. Further studies confirmed that the dimerization was induced by trace transition metals in the HPLC flow path, which could arise from either the stainless steel frits in the LC column or stainless steel tubing in the HPLC instrument. Various procedures to prevent transition metal-induced drug degradation were explored, and a general strategy to mitigate such risks is briefly discussed.

  7. 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

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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)

  13. Analysis of amide compounds in different parts of Piper ovatum Vahl by high-performance liquid chromatographic

    PubMed Central

    Silva, Daniel R.; Brenzan, Mislaine A.; Kambara, Lauro M.; Cortez, Lucia E. R.; Cortez, Diógenes A. G.

    2013-01-01

    Background: Piper ovatum (Piperaceae) has been used in traditional medicine for the treatment of inflammations and as an analgesic. Previous studies have showed important biological activities of the extracts and amides from P. ovatum leaves. Objective: In this study, a high-performance liquid chromatographic (HPLC) method was developed and validated for quantitative determination of the amides in different parts of Piper ovatum. Materials and Methods: The analysis was carried out on a Metasil ODS column (150 × 4.6 mm, 5μm) at room temperature. HPLC conditions were as follows: acetonitrile (A), and water (B), 1.0% acetic acid. The gradient elution used was 0–30 min, 0-60% A; 30–40 min, 60% A. Flow rate used was 1.0mL/min, and detection at 280nm. Results: The validation using piperlonguminine, as the standard, demonstrated that the method shows linearity (linear correlation coefficient = 0.998), precision (relative standard deviation <5%) and accuracy (mean recovery = 103.78%) in the concentration range 31.25 – 500μg/mL. The limit of detection and quantification were 1.21 and 4.03μg/mL, respectively. This method allowed the identification and quantification of piperlonguminine and piperovatine in the hydroethanolic extracts of P. ovatum obtained from the leaves, stems and roots. All the extracts showed the same chromatographic profile. The leaves and roots contained the highest concentrations of piperlonguminine and the stems and leaves showed the most concentrations of piperovatine. Conclusion: This HPLC method is suitable for routine quantitative analysis of amides in extracts of Piper ovatum and phytopharmaceuticals containing this herb. PMID:24174818

  14. Liquid chromatographic determination of sitagliptin either alone or in ternary mixture with metformin and sitagliptin degradation product.

    PubMed

    El-Bagary, Ramzia I; Elkady, Ehab F; Ayoub, Bassam M

    2011-07-15

    Two reversed-phase liquid chromatographic (RP-LC) methods have been developed for the determination of sitagliptin phosphate monohydrate (STG). The first method comprised the determination of STG alone in bulk and plasma; and in its pharmaceutical preparation. This method was based on isocratic elution of STG using a mobile phase consisting of potassium dihydrogen phosphate buffer pH (7.8)-acetonitrile (70:30, v/v) at a flow rate of 1 mL min(-1) with flourometric detection. The flourometric detector was operated at 267 nm for excitation and 575 nm for emission. In the second method, the simultaneous determination of STG and metformin (MET) in the presence of sitagliptin alkaline degradation product (SDP) has been developed. In this method, the ternary mixture of STG, MET and SDP was separated using a mobile phase consisting of potassium dihydrogen phosphate buffer pH (4.6)-acetonitrile-methanol (30:50:20, v/v/v) at a flow rate of 1 mL min(-1) with UV detection at 220 nm. Chromatographic separation in the two methods was achieved on a Symmetry(®) Waters C18 column (150 mm×4.6 mm, 5 μm). Linearity, accuracy and precision were found to be acceptable over the concentration ranges of 0.25-200 μg mL(-1) for STG with the first method and 5-160 μg mL(-1), 25-800 μg mL(-1) for STG and MET, respectively with the second method. The optimized methods were validated and proved to be specific, robust and accurate for the quality control of the cited drugs in pharmaceutical preparations.

  15. 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…

  16. 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%.

  17. 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...

  18. 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

  19. Rapid, fluorimetric-liquid chromatographic determination of malondialdehyde in biological samples.

    PubMed

    Agarwal, Rajiv; Chase, Shawn D

    2002-07-25

    Current chromatographic methods of estimation of malondialdehyde, a marker of oxidative lipid injury, often require extensive extraction procedures, column cleaning or specialized equipment. A rapid and sensitive HPLC method is described for the determination of MDA in plasma and urine. The mobile phase consisted of 40:60 ratio (v/v) of methanol to 50 mM potassium monobasic phosphate at pH 6.8, pumped at a rate of 1.0 ml/min on a Hewlett-Packard Hypersil 5 micro ODS 100 x 4.6 mm placed in a column warmer set to 37 degrees C. Samples of plasma and urine were treated with the antioxidant, butylated hydroxytoluene and heat derivatized at 100 degrees C for 1 h with thiobarbituric acid at an acid pH. Samples were extracted with n-butanol and 10 microl of the extract was injected at 1 min intervals using an autosampler. The Hewlett-Packard model 1046A programmable fluorescence detector was set at excitation of 515 nm and emission of 553 nm. Retention time was 1.87 min, however absence of interfering peaks, allowed analysis to be carried out in increments of 1 min per sample. Within day variability in estimation was between 8.6% and 10.3%. Between days variability was 3.6-7.9%. Recovery was between 88 and 101%. Samples of urine and plasma from ten normotensive volunteers were 1.94 +/- 0.79 micromol/g creatinine and 0.69 +/- 0.13 micromol/l respectively and were similar to those reported in the literature. MDA degrades at room temperature at a rate of 10% per hour. It is therefore, suggested that the total assay time be limited to 1 h beginning with sample preparation.

  20. Evaluation of the phase ratio for three C18 high performance liquid chromatographic columns.

    PubMed

    Caiali, Edvin; David, Victor; Aboul-Enein, Hassan Y; Moldoveanu, Serban C

    2016-02-26

    For a chromatographic column, phase ratio Φ is defined as the ratio between the volume of the stationary phase Vst and the void volume of the column V0, and it is an important parameter characterizing the HPLC process. Although apparently simple, the evaluation of Φ presents difficulties because there is no sharp boundary between the mobile phase and the stationary phase. In addition, the boundary depends not only on the nature of the stationary phase, but also on the composition of the mobile phase. In spite of its importance, phase ratio is seldom reported for commercially available HPLC columns and the data typically provided by the vendors about the columns do not provide key information that would allow the calculation of Φ based on Vst and V0 values. A different procedure for the evaluation of Φ is based on the following formula: log k'j=a log Kow,j+log Φ, where k'j is the retention factor for a compound j that must be a hydrocarbon, Kow,j is the octanol/water partition coefficient, and a is a proportionality constant. Present study describes the experimental evaluation of Φ based on the measurement of k'j for the compounds in the homologous series between benzene and butylbenzene for three C18 columns: Gemini C18, Luna C18 both with 5 μm particles, and a Chromolith Performance RP-18. The evaluation was performed for two mobile phase systems at different proportions of methanol/water and acetonitrile/water. The octanol/water partition coefficients were obtained from the literature. The results obtained in the study provide further support for the new procedure for the evaluation of phase ratio.

  1. Application of Screening Experimental Designs to Assess Chromatographic Isotope Effect upon Isotope-Coded Derivatization for Quantitative Liquid Chromatography–Mass Spectrometry

    PubMed Central

    2015-01-01

    Isotope effect may cause partial chromatographic separation of labeled (heavy) and unlabeled (light) isotopologue pairs. Together with a simultaneous matrix effect, this could lead to unacceptable accuracy in quantitative liquid chromatography–mass spectrometry assays, especially when electrospray ionization is used. Four biologically relevant reactive aldehydes (acrolein, malondialdehyde, 4-hydroxy-2-nonenal, and 4-oxo-2-nonenal) were derivatized with light or heavy (d3-, 13C6-, 15N2-, or 15N4-labeled) 2,4-dinitrophenylhydrazine and used as model compounds to evaluate chromatographic isotope effects. For comprehensive assessment of retention time differences between light/heavy pairs under various gradient reversed-phase liquid chromatography conditions, major chromatographic parameters (stationary phase, mobile phase pH, temperature, organic solvent, and gradient slope) and different isotope labelings were addressed by multiple-factor screening using experimental designs that included both asymmetrical (Addelman) and Plackett–Burman schemes followed by statistical evaluations. Results confirmed that the most effective approach to avoid chromatographic isotope effect is the use of 15N or 13C labeling instead of deuterium labeling, while chromatographic parameters had no general influence. Comparison of the alternate isotope-coded derivatization assay (AIDA) using deuterium versus 15N labeling gave unacceptable differences (>15%) upon quantifying some of the model aldehydes from biological matrixes. On the basis of our results, we recommend the modification of the AIDA protocol by replacing d3-2,4-dinitrophenylhydrazine with 15N- or 13C-labeled derivatizing reagent to avoid possible unfavorable consequences of chromatographic isotope effects. PMID:24922593

  2. Application of screening experimental designs to assess chromatographic isotope effect upon isotope-coded derivatization for quantitative liquid chromatography-mass spectrometry.

    PubMed

    Szarka, Szabolcs; Prokai-Tatrai, Katalin; Prokai, Laszlo

    2014-07-15

    Isotope effect may cause partial chromatographic separation of labeled (heavy) and unlabeled (light) isotopologue pairs. Together with a simultaneous matrix effect, this could lead to unacceptable accuracy in quantitative liquid chromatography-mass spectrometry assays, especially when electrospray ionization is used. Four biologically relevant reactive aldehydes (acrolein, malondialdehyde, 4-hydroxy-2-nonenal, and 4-oxo-2-nonenal) were derivatized with light or heavy (d3-, (13)C6-, (15)N2-, or (15)N4-labeled) 2,4-dinitrophenylhydrazine and used as model compounds to evaluate chromatographic isotope effects. For comprehensive assessment of retention time differences between light/heavy pairs under various gradient reversed-phase liquid chromatography conditions, major chromatographic parameters (stationary phase, mobile phase pH, temperature, organic solvent, and gradient slope) and different isotope labelings were addressed by multiple-factor screening using experimental designs that included both asymmetrical (Addelman) and Plackett-Burman schemes followed by statistical evaluations. Results confirmed that the most effective approach to avoid chromatographic isotope effect is the use of (15)N or (13)C labeling instead of deuterium labeling, while chromatographic parameters had no general influence. Comparison of the alternate isotope-coded derivatization assay (AIDA) using deuterium versus (15)N labeling gave unacceptable differences (>15%) upon quantifying some of the model aldehydes from biological matrixes. On the basis of our results, we recommend the modification of the AIDA protocol by replacing d3-2,4-dinitrophenylhydrazine with (15)N- or (13)C-labeled derivatizing reagent to avoid possible unfavorable consequences of chromatographic isotope effects. PMID:24922593

  3. Decoding glycome of Astragalus membranaceus based on pressurized liquid extraction, microwave-assisted hydrolysis and chromatographic analysis.

    PubMed

    Lv, G P; Hu, D J; Cheong, K L; Li, Z Y; Qing, X M; Zhao, J; Li, S P

    2015-08-28

    Carbohydrates in herbs are a relatively untapped source of new drugs and health beneficial ingredients. Their analysis has been developed as a novel aspect in quality control and herbal glycomics. In this study, glycome of Astragalus membranaceus was decoded based on optimized pressurized liquid extraction (PLE), microwave-assisted acidic hydrolysis (MAAH) and comprehensive chromatographic approaches. Twelve saccharides including sucrose, galacturonic acid, mannitol, fructose, rhamnose, ribose, arabinose, fucose, xylose, mannose, glucose and galactose were quantitatively analyzed by GC-MS and HPLC-CAD (charged aerosol detectors). Different columns, including Prevail Carbohydrate ES, XBridge Amide and CARBOSep CHO-820 CA for HPLC-CAD analysis, were compared for evaluation of oligosaccharides. The polysaccharides in water extract of Astragalus membranaceus were characterized by high performance size exclusive chromatography (HPSEC) combined with multiple angle light scattering detection (MALSD) and refractive index detection (RID). The results showed that A. membranaceus contained more than 108.5mgg(-1) free sucrose and small amounts of glucose 9.6-26.0mgg(-1) and fructose 8.7-22.9mgg(-1). While its polymeric carbohydrates were composed of glucose 71.0-162.3mgg(-1), galacturonic acid 52.0-113.4mgg(-1), arabinose 22.8-54.4mgg(-1) and small amounts of galactose, rhamnose, xylose and mannose. CARBOSep CHO-820 CA showed its potential in simultaneously analyzing oligosaccharides and uronic acid, especially only the environment-friendly water mobile phase was used. HPSEC-MALSD-RID showed that there were three different molecular weight distributions of polysaccharides in A. membranaceus and the average molecular weight were 21901.1, 2038.5, and 353.4kDa. Hierarchical clustering analysis and principal component analysis demonstrated that A. membranaceus from different regions showed variations both in free and polymeric carbohydrates, which indicated that carbohydrates

  4. 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

  5. Liquid-phase cavity ring-down spectroscopy and its application as a chromatographic detector

    NASA Astrophysics Data System (ADS)

    Bechtel, Kate L.

    A new liquid-phase absorption detector is developed that demonstrates a minimum detectable absorbance of 10-8 absorbance units (AU). This value is more than 40 times lower than commercially available UV-Vis detectors. This new detector is a result of the extension of cavity ring-down spectroscopy (CRDS), a primarily gas-phase technique, to the liquid phase. Liquid-phase CRDS is accomplished by incorporating a specially designed flow cell into the ring-down cavity. The flow cell minimizes optical losses by allowing p-polarized light to refract through the cell interfaces at Brewster's angle. This flow cell has been coupled to the output of an HPLC separation, enabling the detection of analytes by CRDS. This technique was initially demonstrated by the separation and detection of a series of anthraquinones using a pulsed laser source at 470 nm. Ring-down time constants with the Brewster's angle flow cell, having an interior optical pathlength of 0.3 mm, were up to 2.5 mus in a 1-m cavity. The baseline noise level (rms) of this system was 3.2 x 10-6 AU, rivaling the best commercial UV-Vis detector, which exhibits a baseline noise of 3.0 x 10-6 AU. The CRDS detector performance, while notable, was limited in this case because of the nature of the light source: excitation of multiple cavity modes resulted in a 1% shot-to-shot variation in the ring-down time constant. The detection limit of the liquid-phase CRDS detector was improved through the use of a single-mode continuous-wave (cw) laser source at 488 nm. Its narrow linewidth enabled excitation of a single cavity mode, resulting in shot-to-shot variations in the ring-down time constant as low as 0.04%. Furthermore, through improved cell characterization, ring-down time constants with the same flow cell and cavity length were nearly 6 mus. The baseline noise (rms) for this system during an HPLC separation of the same analytes was 6.7 x 10-8 AU. These results clearly illustrate the value of liquid-phase CRDS and its

  6. 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.

  7. 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

  8. 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.

  9. 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

  10. Liquid chromatographic analysis of coal surface properties. Quarterly progress report, September--December 1991

    SciTech Connect

    Kwon, K.C.

    1991-12-31

    The main objectives of this proposed research 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 floatability of various treated coals in conjunction with surface properties of coals. Alcohols such as methanol, ethanol, isopropanol, isobutanol, tert-butanol, heptanol, 1-hexadecanol, 2-methyl-pentanol, 4-methyl-2-penthanol (methylisobutyl carbinol), n-octanol, s-octanol, and cyclohexanol as probe compounds are utilized to evaluate hydrophilicity of coals and coal minerals. N-alkanes such as hexane, heptane and octane, and stearic acid are employed as probe compounds to evaluate hydrophobicity of coals and coal minerals. Aromatic compounds such as benzene and toluene as probe compounds are used to examine aromaticity of coal surface. Aromatic acids such as o-cresol, m-cresol, p-cresol, phenol and B-naphthol are used to detect aromatic acidic sites of coal surface. Hydrophilicity, hydrophobicity and aromaticity of surfaces for either raw coals or treated coals in water are relatively determined by evaluating both equilibrium physical/chemical adsorption and dynamic adsorption of probe compounds on various raw coals and treated coals to compare affinities of coals for water.

  11. Rapid liquid chromatographic-mass spectrometric assay for oxymetazoline in whole rat blood.

    PubMed

    Hayes, F J; Baker, T R; Dobson, R L; Tsueda, M S

    1995-02-10

    A rapid HPLC-electrospray mass spectrometric assay for the quantitation of oxymetazoline in whole rat blood has been developed. Sample preparation was a single liquid-liquid extraction after addition of a deuterated internal standard (IS) and pH adjustment. An aliquot of reconstituted extract was injected onto a narrow-bore octadecyl reversed-phase column at a flow-rate of 400 microliters/min. Using a 20:1 post-column split, 5% of the eluent was introduced into the mass spectrometer interface. Elution of the analyte and IS occurred in less than 2 min. This rapid separation was made possible because of the sample cleanup and the selectivity of the mass spectrometric detection. The [M+H]+ ions for oxymetazoline (m/z 261) and [2H9]oxymetazoline (m/z 270) were detected using selected ion monitoring. The linear range of the assay was 0.67-167 ng/g of blood and the limit of quantitation with a 0.30-g sample was 1.0 ng/g. The assay permitted the analysis of nine samples per hour with the requisite sensitivity and selectivity and was used to determine the blood pharmacokinetics of oxymetazoline in rats dosed via intravenous and intranasal routes.

  12. Liquid chromatographic method for determination of patulin in clear and cloudy apple juices and apple puree: collaborative study.

    PubMed

    MacDonald, S; Long, M; Gilbert, J; Felgueiras, I

    2000-01-01

    A collaborative trial was conducted to validate the effectiveness of a liquid chromatographic (LC) procedure for determination of patulin in both clear and cloudy apple juices and apple puree. The test portion of clear apple juice was directly extracted with ethyl acetate; cloudy apple juice and apple puree were treated with pectinase enzyme before extraction. After back-extraction into sodium carbonate to remove interfering acidic compounds, the extract was dried and concentrated, and patulin was determined by LC with UV detection. Clear and cloudy apple juices, apple puree test samples naturally contaminated with patulin, and blank test samples for spiking with patulin were sent to 14 collaborators in 12 different European countries. Test portions of each of the 3 test sample types were spiked with patulin at 75 ng/g. Recoveries of patulin ranged from 80 to 92%. Based on the results for spiked test samples (blind pairs) and naturally contaminated test samples (blind pairs at 3 levels), the relative standard deviations for repeatability (RSDr) and reproducibility (RSDR) ranged from 8 to 35% and 11 to 36%, respectively. Although HORRAT values of <1.4 were obtained for all 3 matrixes at patulin levels ranging from 26 to 121 ng/g, better performance values (RSDr values 6-10% and RSDR values 11-25%) were obtained for clear and cloudy apple juice spiked above 50 ng/g, which is either the statutory limit or the advisory level for patulin contamination in apple juices in many countries.

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

    PubMed

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

    2015-05-01

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

  14. 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.

  15. Chromatographic characterization of hydrophilic interaction liquid chromatography stationary phases: hydrophilicity, charge effects, structural selectivity, and separation efficiency.

    PubMed

    Kawachi, Yuusuke; Ikegami, Tohru; Takubo, Hirotaka; Ikegami, Yuka; Miyamoto, Masatoshi; Tanaka, Nobuo

    2011-09-01

    Fourteen commercially available particle-packed columns and a monolithic column for hydrophilic interaction liquid chromatography (HILIC) were characterized in terms of the degree of hydrophilicity, the selectivity for hydrophilic-hydrophobic substituents, the selectivity for the regio and configurational differences in hydrophilic substituents, the selectivity for molecular shapes, the evaluation of electrostatic interactions, and the evaluation of the acidic-basic nature of the stationary phases using nucleoside derivatives, phenyl glucoside derivatives, xanthine derivatives, sodium p-toluenesulfonate, and trimethylphenylammonium chloride as a set of samples. Principal component analysis based on the data of retention factors could separate three clusters of the HILIC phases. The column efficiency and the peak asymmetry factors were also discussed. These data on the selectivity for partial structural differences were summarized as radar-shaped diagrams. This method of column characterization is helpful to classify HILIC stationary phases on the basis of their chromatographic properties, and to choose better columns for targets to be separated. Judging from the retention factor for uridine, these HILIC columns could be separated into two groups: strongly retentive and weakly retentive stationary phases. Among the strongly retentive stationary phases, zwitterionic and amide functionalities were found to be the most selective on the basis of partial structural differences. The hydroxyethyl-type stationary phase showed the highest retention factor, but with low separation efficiency. Weakly retentive stationary phases generally showed lower selectivity for partial structural differences. PMID:21782195

  16. 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

  17. 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.

  18. Liquid chromatographic separation and fluorometric determination of cis- and trans-isoeugenol in perfumes, colognes, and toilet waters.

    PubMed

    Wisneski, H H; Yates, R L; Wenninger, J A

    1988-01-01

    A liquid chromatographic (LC)-fluorometric method is described for the determination of cis- and trans-isoeugenol (2-methoxy-4-propenylphenol) in perfumes, colognes, and toilet waters. A test portion of the product is added to diethyl ether, and the isoeugenol isomers are extracted with sodium hydroxide solution. The basic extract is then acidified, and the isoeugenol isomers are extracted with isooctane. Aliquots of the isooctane extract are analyzed by using a silver ion cation exchange LC column interfaced to a spectrophotofluorometer. Each isomer in the product is determined by comparing its fluorescence emission intensity with that of an external standard consisting of a mixture of both isomers in which the relative concentration of each has been determined. Average recoveries from various commercial fragrances fortified with a mixture of cis- and trans-isoeugenol with total isoeugenol content of 0.1, 0.5, and 4.0 mg/mL ranged from 87 to 105% for the trans-isomer (SD = 4.6%) and from 83 to 113% for the cis-isomer (SD = 6.7%). The limit of determination is approximately 0.002 mg/mL.

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. 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

  4. Liquid chromatographic method for the micro-quantitative determination of clodinafop in soil, wheat and Phalaris minor.

    PubMed

    Roy, Sugata; Singh, Shashi Bala

    2005-02-18

    A liquid chromatographic method was developed for the determination of clodinafop-propargyl herbicide. Clodinafop-propargyl was converted to clodinafop acid by alkaline hydrolysis as clodinafop-propargyl rapidly forms bioactive clodinafop acid in soil and plant environment. Recovery methods for both the acid and ester from different matrices were standardized. The sensitivity of the method for ester and acid was 5 and 2 ng, respectively, with limits of detection of 0.5 and 0.1 microg ml(-1). The method was standardized for the determination of clodinafop residues in soil and plant samples using HPLC. The recovery of clodinafop from soil and plant samples with ethyl acetate was significantly higher (78-83%) than those with dichloromethane, toluene and methanol (60-70%). The limit of determination of clodinafop in soil and plant samples ranged between 1 and 1.2 ng g(-1). In field soil, residues of clodinafop dissipated with a half-life of 3.44 days.

  5. [A reversed-phase high performance liquid chromatographic method for the determination of pinoresinol diglucopyranoside in Eucommia Ulmoides Oliv].

    PubMed

    Qi, X; Zhang, S

    1998-03-01

    A reversed-phase high performance liquid chromatographic method for the determination of (+)-pinoresinol-di-O-beta-D-glucopyranoside in the bark of Eucommia Ulmoides was established. The air-dried bark of E. Ulmoides was ground into powder and extracted continuously with methanol. The extract was evaporated under reduced pressure, then suspended in water. This suspension being subjected to column chromatography was eluted successively with water, 30%, 50% and 90% aqueous solution of ethanol. The 30% EtOH eluate was concentrated and then injected into HPLC system. The conditions of HPLC were: YWG-C18 column (250 mm x 4.6 mm i.d. 10 microns); 28%(V/V) methanol mobile phase and UV detector at 232 nm. The calibration curve was linear in the range of 0.068 microgram-0.68 microgram of(+)-pinoresinol-di-O-beta-D-glucopyranoside with correlation coefficient of 0.9999. The coefficient of variation and average recovery were 0.50%-0.74% (n = 5) and 99.22% (n = 3) respectively.

  6. Reversed-phase liquid chromatographic profile of free amino acids in strawberry-tree (Arbutus unedo L.) honey.

    PubMed

    Spano, Nadia; Piras, Irene; Ciulu, Marco; Floris, Ignazio; Panzanelli, Angelo; Pilo, Maria I; Piu, Paola C; Sanna, Gavino

    2009-01-01

    The typical profile of the free amino acids contained in strawberry-tree (Arbutus unedo L.) honey is reported for the first time. An optimized reversed-phase liquid chromatographic (RP-LC) method with phenyl isothiocyanate precolumn derivatization was used. Fourteen free amino acids were identified and quantified in 16 analytical samples. Proline (65.63%) was found to be the most abundant free amino acid, followed by glutamic acid (6.49%), arginine (5.21%), alanine (5.17%), and phenylalanine (4.97%). The total free amino acid content of strawberry-tree honey (average value, 436 mg/kg) was found to be low in comparison to amounts cited in the literature concerning unifloral honeys. The analytical method was optimized and fully validated in terms of detection and quantitation limits, precision (by testing repeatability and reproducibility), linearity, and bias (by means of recovery tests). The acceptability of the validation protocol results was verified using Horwitz's mathematical model and AOAC guidelines. PMID:19714983

  7. Single-walled carbon nanotube-based polymer monoliths for the enantioselective nano-liquid chromatographic separation of racemic pharmaceuticals.

    PubMed

    Ahmed, Marwa; Yajadda, Mir Massoud Aghili; Han, Zhao Jun; Su, Dawei; Wang, Guoxiu; Ostrikov, Kostya Ken; Ghanem, Ashraf

    2014-09-19

    Single-walled carbon nanotubes were encapsulated into different polymer-based monolithic backbones. The polymer monoliths were prepared via the copolymerization of 20% monomers, glycidyl methacrylate, 20% ethylene glycol dimethacrylate and 60% porogens (36% 1-propanol, 18% 1,4-butanediol) or 16.4% monomers (16% butyl methacrylate, 0.4% sulfopropyl methacrylate), 23.6% ethylene glycol dimethacrylate and 60% porogens (36% 1-propanol, 18% 1,4-butanediol) along with 6% single-walled carbon nanotubes aqueous suspension. The effect of single-walled carbon nanotubes on the chiral separation of twelve classes of pharmaceutical racemates namely; α- and β-blockers, antiinflammatory drugs, antifungal drugs, dopamine antagonists, norepinephrine-dopamine reuptake inhibitors, catecholamines, sedative hypnotics, diuretics, antihistaminics, anticancer drugs and antiarrhythmic drugs was investigated. The enantioselective separation was carried out under multimodal elution to explore the chiral recognition capabilities of single-walled carbon nanotubes using reversed phase, polar organic and normal phase chromatographic conditions using nano-liquid chromatography. Baseline separation was achieved for celiprolol, chlorpheniramine, etozoline, nomifensine and sulconazole under multimodal elution conditions. Satisfactory repeatability was achieved through run-to-run, column-to-column and batch-to-batch investigations. Our findings demonstrate that single-walled carbon nanotubes represent a promising stationary phase for the chiral separation and may open the field for a new class of chiral selectors.

  8. Liquid chromatographic analysis of phosphoamino acids at femtomole level using chemical derivatization with N-hydroxysuccinimidyl fluorescein-O-acetate.

    PubMed

    Deng, Ying-Hua; Li, Rong-Jun; Zhang, Hua-Shan; Du, Xiao-Lan; Wang, Hong

    2007-10-01

    Phosphorylation of amino acid residues in proteins plays a major role in biological systems. In this paper, a reversed-phase high performance liquid chromatographic (HPLC) method based on chemical derivatization has been described for the separation and quantification of phosphoamino acids at femtomole level, using fluorimetric detection (FLD). The protocol involved pre-column derivatization of phosphoamino acids with N-hydroxysuccinimidyl fluorescein-O-acetate (SIFA) and subsequent separation on ZORBAX Eclipse XDB-C8 column. Several experimental factors that influenced derivatization and separation were carefully investigated. The derivatization was performed at 40 degrees C for 40 min in borate buffer (pH 8.5). Under the optimum conditions, phosphoserine (P-Ser), phosphothreonine (P-Thr) and phosphotyrosine (P-Tyr) were satisfactorily separated in 8 min. The detection limits (signal-to-noise ratio=3) for the phosphoamino acids could reach 10-20 fmol, which was the lowest value reported for HPLC methods and comparable to those obtained by capillary electrophoresis with laser-induced fluorescence (CE-LIF) detection methods. The proposed method has been validated and used to characterize the phosphoamino acids in the hydrolyzed phosphorylated protein samples. The results clearly demonstrated the potential of this technique to study phosphoamino acids as well as provided a new analytical methodology that should be applicable to the study of phosphorylation of protein in biological system.

  9. Improved liquid chromatographic method for determination of organic acids in leaves, pulp, fruits, and rinds of Garcinia.

    PubMed

    Jayaprakasha, Guddadarangavvanahally K; Jena, Bhabani S; Sakariah, Kunnumpurath K

    2003-01-01

    An improved liquid chromatographic (LC) method was developed for determination of organic acids in leaves, pulp, fruits, and rinds of Garcinia. At present, the commonly used LC method for analysis of organic acids in Garcinia extracts uses direct application of the extracts on the column. This practice gradually reduces efficiency of the column and shortens its life. In the improved method, the interfering substances such as pigments and xanthones were effectively removed by passing the aqueous extract through an ODS cartridge. With subsequent injection on a C18 reversed-phase column, using 6.0 mM phosphoric acid as the mobile phase with a flow rate of 1.0 mL/min and UV detection at 210 nm, the organic acids were determined in the extracts. The major organic acid was (-)-hydroxycitric acid at the level of 2.5, 0.8, 3.0, and 20.1% in leaf, pulp, fresh fruit, and dried rinds, respectively. Minor quantities of hydroxycitric acid lactone, oxalic acid, and citric acid were also identified. Limits of detection and recoveries were 0.9-1.5 microg and 93.9-99.8%, respectively. This is the first report on the composition of organic acids from Garcinia pedunculata.

  10. A salt-free isocratic high-pressure liquid chromatographic method for the quantitation of benzodiazepines in serum.

    PubMed

    Tai, H L; Osiewicz, R J; Bofinger, D P

    1993-06-01

    A simple, rapid high-pressure liquid chromatography (HPLC) method was developed for detecting and quantifying benzodiazepines in serum. Seven major benzodiazepines were extracted from spiked serum samples using solid-phase extraction with prazepam as the internal standard. The eluted drugs were then resolved isocratically by HPLC within 11 min using a reversed-phase C8 column with a mobile phase consisting of acetonitrile, methanol, water, and perchloric acid. All drugs gave responses that varied linearly with concentration over the ranges studied. Within-day imprecision (CV) varied from 3.9 to 14.9%, day-to-day CV from 4.8 to 17.0%, absolute recoveries from 67% to 114%, and detection limits from 10 to 110 ng/mL. Tricyclic antidepressants did not interfere, and clinical results were in good agreement with those obtained by a gas chromatographic method. The advantage of this method is that it uses a salt-free isocratic mobile phase that can be easily manipulated to effect difficult benzodiazepine separations.

  11. Fifteen years of operation of a high-performance liquid chromatographic assay for prednisolone, cortisol and prednisone in plasma.

    PubMed

    Jusko, W J; Pyszczynski, N A; Bushway, M S; D'Ambrosio, R; Mis, S M

    1994-08-01

    A high-performance liquid chromatographic (HPLC) assay first described in 1979 has been modified and revalidated for the simultaneous determination of prednisone, cortisol and prednisolone in human plasma using betamethasone as an internal standard. Revisions include: mobile phase composition; use of a precolumn, automated injector, integrator, and computer software; improved sensitivity and quantitation; thorough investigation of stability, variation, and specimen type; and inclusion of suggested quality control criteria. Plasma-based drug standards are extracted with methylene chloride and washed with sodium hydroxide followed by a water wash. After evaporation of solvent and reconstitution with mobile phase, the extracts are then injected onto a silica gel column (Zorbax SIL) for chromatography with UV absorbance at 254 nm. Calculated limits of quantitation are 10 ng/ml and limits of detection are less than 5 ng/ml. Intra- and inter-day coefficients of variation for quality control samples for all three corticosteroids are less than 11.2%. Recovery and stability data are also provided. Several drugs that may be coadministered do not interfere with the analysis.

  12. Gas chromatographic separation of fatty acid esters of cholesterol and phytosterols on an ionic liquid capillary column.

    PubMed

    Hammann, Simon; Vetter, Walter

    2015-12-15

    Steryl esters are high molecular weight compounds (600-700g/mol) regularly present as a minor lipid class in animal and plant lipids. Different sterol backbones (e.g., cholesterol, β-sitosterol and brassicasterol) which can be esterified with various fatty acids can result in highly complex steryl ester patterns in food samples. The gas chromatographic (GC) analysis of intact steryl esters is challenging, since high elution temperatures are required for their elution. On nonpolar GC phases, steryl esters with fatty acids with differing degree of unsaturation (e.g., oleate and linoleate) cannot be separated and there are only few polar columns available with sufficient temperature stability. In this study, we used gas chromatography with mass spectrometry (GC/MS) and analyzed intact steryl esters on a commercial room temperature ionic liquid (RTIL) column which was shortened to a length of 12m. The column separated the steryl esters both by total carbon number and by degree of unsaturation of the fatty acid. For instance, cholesteryl esters with stearic acid (18:0), oleic acid (18:1n-9), linoleic acid (18:2n-6) and α-linolenic acid (18:3n-3) could be resolved (R≥1.3) from each other. By analysis of synthesized standard substances, the elution orders for different steryl backbones and different fatty acids on a given sterol backbone could be determined. Analysis of spreads and plant oils allowed to determine retention times for 37 steryl esters, although a few co-elutions were observed. The ionic liquid column proved to be well-suited for the analysis of intact steryl esters.

  13. Chromatographic purification and characterization of B-phycoerythrin from Porphyridium cruentum. Semipreparative high-performance liquid chromatographic separation and characterization of its subunits.

    PubMed

    Bermejo, R; Talavera, E M; Alvarez-Pez, J M

    2001-05-11

    A fast preparative two-step chromatographic method for purification of B-phycoerythrin from Porphyridium cruentum is described. This biliprotein was homogeneous as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis yielding three closely migrating bands corresponding to its three subunits. Baseline separation of its alpha-, beta- and gamma-subunits was achieved by a reversed-phase HPLC gradient semipreparative method with a C4 large-pore column and a solvent system consisting of 0.05% trifluoroacetic acid (TFA) in water and 0.05% TFA in acetonitrile. B-Phycoerythrin in different aggregation states and its subunits have been spectroscopically characterized. Hexameric B-phycoerythrin has similar secondary and tertiary structure than dissociated B-phycoerythrin determined by circular dichroism.

  14. High-performance liquid chromatographic analysis of chemical stability of 5-aza-2'-deoxycytidine.

    PubMed

    Lin, K T; Momparler, R L; Rivard, G E

    1981-11-01

    The chemical stability of 5-aza-2'-deoxycytidine (I) in acidic, neutral, and alkaline solutions was analyzed by high-performance liquid chromatography. In alkaline solution, I underwent rapid reversible decomposition to N-(formylamidino)-N'-beta-D-2-deoxyribofuranosylurea (II), which decomposed irreversibly to form 1-beta-D-2'-deoxyribofuranosyl-3-guanylurea (III). The pseudo-first-order rate constants for this reaction were determined. The decomposition of I in alkaline solution was identical to that reported previously for the related analog, 5-aza-cytidine. However, in neutral solution (or water), there was a marked difference in the decomposition of I and 5-azacytidine. The same decomposition products were formed from 5-azacytidine in neutral solution as in alkaline solution. However, in neutral solution, I decomposed to II and three unknown compounds that were chromophoric at 254 nm. Compound I was most stable when stored in neutral solution at low temperature.

  15. 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.

  16. 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

  17. Sensitive high-performance liquid chromatographic determination of chlorpheniramine in human serum using column switching.

    PubMed

    Yamaguchi, M; Monji, H; Yamashita, K; Aoki, I; Yashiki, T

    1994-11-01

    A sensitive method for the determination of chlorpheniramine in human serum was developed using column-switching high-performance liquid chromatography (HPLC) with ultraviolet detection at 210 nm. The analyte was extracted with diethyl ether from alkalinized serum. After evaporation of the organic layer, the reconstituted residue was analyzed by HPLC using a heart-cut technique. Good recoveries of the analyte from spiked human serum samples were obtained with a coefficient of variation below 7%. A good linear response was obtained for the concentration range 0.5-50 ng/ml, with a correlation coefficient higher than 0.999. The lower limit of quantitation for chlorpheniramine in human serum was 0.5 ng/ml. The method was satisfactorily applied to the determination of chlorpheniramine in human serum after oral administration of chlorpheniramine maleate.

  18. Self-immobilization of poly(methyloctylsiloxane) on high-performance liquid chromatographic silica.

    PubMed

    Collins, Kenneth E; Bottoli, Carla B G; Vigna, Camila R M; Bachmann, Stefan; Albert, Klaus; Collins, Carol H

    2004-03-12

    Poly(methyloctylsiloxane) (PMOS) was deposited on HPLC silica by a solvent evaporation procedure and this material was then extracted, using a good solvent for the PMOS, after different time periods, to remove unretained liquid polymer. Solvent extraction data reveal changes which occur at ambient temperature as a function of the time interval between particle loading and extraction. The quantity of PMOS remaining on the silica after extraction, as determined by elemental analysis for carbon, is attributed to strongly adsorbed polymer. This phenomenon is termed self-immobilization. Solid-state 29Si NMR spectra indicate the formation of a silicon species with a different chemical shift than the original PMOS. These new signals are attributed to a combination of different adsorbed and chemically bonded groups.

  19. High-performance liquid chromatographic method of photoactive compounds based on diazonaphthoquinone for positive photoresists.

    PubMed

    Kim, Byoung-Hyoun; Kim, Yon Hee; Moon, Dong Cheul

    2013-02-01

    An analytical method for the compositional and quantitative analysis of photoactive compounds (PACs) in positive photoresist (Posi PR) has been developed by high-performance liquid chromatography (HPLC). Under optimum HPLC conditions, various types of PACs consisting of a mixture of isomers were satisfactorily separated with no interference. This method was applied to the quantitative analysis of PACs in Posi PR. All correlation coefficients were better than or equal to 0.998. The precision and accuracy showed no significant deviation and were measured with acceptable values. The intra-batch precision and accuracy (%) of quality control samples ranged from 0.80 to 1.46% and from 101.7 to 102.8%. Consequently, the method was demonstrated to be acceptable for the analysis of PACs in Posi PR. We believe that the HPLC method developed in this work can be used for the compositional and quantitative analysis of PACs in Posi PR.

  20. Reverse-phase liquid chromatographic determination of clioquinol in cream and ointment preparations: collaborative study.

    PubMed

    Wojtowicz, E J

    1989-01-01

    Seven laboratories participated in a collaborative study to analyze, in duplicate, 2 synthetic formulations and 2 commercial preparations, labeled to contain 3% clioquinol. Clioquinol is determined as its nickel (II) complex by reverse-phase liquid chromatography on a phenyl-bonded column with a mobile phase of acetonitrile-methanol-water, containing ammonium acetate and nickel chloride. Detection is at 273 nm and diphenylamine is added as an internal standard. Mean recoveries were 99.1 and 101.1%, respectively, for the ointment and cream synthetic preparations and 96.7 and 99.7%, respectively, for the commercial ointment and cream. All results are consistent with the variability of other methods at this concentration range. The method has been approved interim official first action.

  1. 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)

  2. Direct high-performance liquid chromatographic enantioseparation of free α-, β- and γ-aminophosphonic acids employing cinchona-based chiral zwitterionic ion exchangers.

    PubMed

    Gargano, Andrea F G; Kohout, Michal; Macíková, Pavla; Lämmerhofer, Michael; Lindner, Wolfgang

    2013-10-01

    We report a chiral high-performance liquid chromatographic enantioseparation method for free α-aminophosphonic, β-aminophosphonic, and γ-aminophosphonic acids, aminohydroxyphosphonic acids, and aromatic aminophosphinic acids with different substitution patterns. Enantioseparation of these synthons was achieved by means of high-performance liquid chromatography on CHIRALPAK ZWIX(+) and ZWIX(-) (cinchona-based chiral zwitterionic ion exchangers) under polar organic chromatographic elution conditions. Mobile phase characteristics such as acid-to-base ratio, type of counterion, and solvent composition were systematically varied in order to investigate their effect on the separation performance and to achieve optimal separation conditions for the set of analytes. Under the optimized conditions, 32 of 37 racemic aminophosphonic acids studied reached baseline separation when we employed a single generic mass-spectrometry-compatible mobile phase, with reversal of the elution order when we used (+) and (-) versions of the chiral stationary phase.

  3. Direct high-performance liquid chromatographic enantioseparation of free α-, β- and γ-aminophosphonic acids employing cinchona-based chiral zwitterionic ion exchangers.

    PubMed

    Gargano, Andrea F G; Kohout, Michal; Macíková, Pavla; Lämmerhofer, Michael; Lindner, Wolfgang

    2013-10-01

    We report a chiral high-performance liquid chromatographic enantioseparation method for free α-aminophosphonic, β-aminophosphonic, and γ-aminophosphonic acids, aminohydroxyphosphonic acids, and aromatic aminophosphinic acids with different substitution patterns. Enantioseparation of these synthons was achieved by means of high-performance liquid chromatography on CHIRALPAK ZWIX(+) and ZWIX(-) (cinchona-based chiral zwitterionic ion exchangers) under polar organic chromatographic elution conditions. Mobile phase characteristics such as acid-to-base ratio, type of counterion, and solvent composition were systematically varied in order to investigate their effect on the separation performance and to achieve optimal separation conditions for the set of analytes. Under the optimized conditions, 32 of 37 racemic aminophosphonic acids studied reached baseline separation when we employed a single generic mass-spectrometry-compatible mobile phase, with reversal of the elution order when we used (+) and (-) versions of the chiral stationary phase. PMID:23748643

  4. Ultra-performance liquid chromatographic determination of tocopherols and retinol in human plasma.

    PubMed

    Bell, Edward C; John, Mathew; Hughes, Rodney J; Pham, Thu

    2014-10-01

    A rapid, selective and sensitive ultra-performance liquid chromatography method has been developed for the detection and quantification of tocopherols and retinol in human plasma. Alpha-tocopherol, gamma-tocopherol and retinol are assayed using fluorescence detection. Excitation/emission wavelengths are 295/330 nm and 325/470 nm for the analysis of both tocopherols and retinol, respectively. Retinol acetate is employed as the internal standard. The reversed-phase method incorporates gradient elution with a mobile phase consisting of methanol and acetonitrile. Separation of vitamin compounds is achieved using a bridged ethyl hybrid C18 column. The retention times for retinol, retinol acetate, gamma-tocopherol and alpha-tocopherol are 1.6, 1.8, 3.9 and 4.3 min, respectively. The limits of quantification for retinol, gamma-tocopherol and alpha-tocopherol were 0.02, 0.02 and 0.1 µg/mL, respectively. The assay method is suitable for the analysis of tocopherols and retinol in human plasma. The method may be applied following the ingestion of foods fortified with these fat-soluble vitamins.

  5. 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

  6. 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

  7. Development of high-performance liquid chromatographic for quality and authenticity control of Chinese propolis.

    PubMed

    Cui-ping, Zhang; Shuai, Huang; Wen-ting, Wei; Shun, Ping; Xiao-ge, Shen; Ya-jing, Li; Fu-liang, Hu

    2014-07-01

    A RP-high-performance liquid chromatography (HPLC) method was developed for quality control of Chinese propolis by simultaneous analysis of 12 flavonoids and 8 phenolic acids. The results showed that vanillic acid, rutin, myricetin, and luteolin were not detected in all of the analyzed propolis and poplar tree gum samples. The caffeic acid, ferulic acid and p-coumaric acid were not detected in poplar tree gum but were detected in propolis, which suggest that they are practical indexes of distinguishing propolis from poplar tree gum. The flavonoid profiles of poplar tree gum were found to be similar to those of propolis, which are dominated by pinobanksin, pinocembrin, 3-O-acetylpinobanksin, chrysin, and galangin. Therefore, the proposed method could be applied to exclude poplar tree gum from propolis with cafferic acid, ferulic acid, and p-coumaric acid as qualitative markers, and distinguish poplar source resin from other illegal substances, and evaluate the quality grading of poplar-type propolis with pinobanksin, pinocembrin, 3-O-acetylpinobanksin, chrysin, and galangin as qualitative and quantitative markers.

  8. 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

  9. 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

  10. High-performance liquid chromatographic determination of linoleic acid peroxide-derived radicals using electrochemical detection.

    PubMed

    Iwahashi, H

    2000-12-29

    High-performance liquid chromatography-electrochemical detection (HPLC-ED) was applied to detect 13-hydroperoxide octadecadienoic acid (13-HPODE)-derived radicals such as the pentyl radical and octanoic acid radical. The 13-HPODE-derived radicals were successfully detected using HPLC-ED by the combined use of the spin-trapping technique with alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN). The 4-POBN-pentyl radical adduct was detected at the retention time of 18.2 +/- 0.3 min on the elution profile of HPLC-ED with an ODS column (15 cm x 4.6 mm I.D.) using a flow-rate of 1.0 ml/min with 50 mM ammonium acetate in 29% (v/v) aqueous acetonitrile. The 4-POBN-octanoic acid radical adduct was also detected at the retention time of 13.7 +/- 0.7 min using a flow-rate of 1.0 ml/min with 50 mM ammonium acetate in 14% (v/v) aqueous acetonitrile. The concentrations of the 4-POBN radical adducts were determined using HPLC-ED without an internal standard. HPLC-ED is 100 times as sensitive as HPLC-electron spin resonance (ESR) under the ESR and ED conditions employed here. Even 1.8 pmol of the 4-POBN-pentyl (or octanoic acid) radical adduct was detectable using PMID:11204234

  11. 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

  12. Sensitive high performance liquid chromatographic assay for assessment of doxorubicin pharmacokinetics in mouse plasma and tissues.

    PubMed

    Urva, Shweta R; Shin, Beom Soo; Yang, Victor C; Balthasar, Joseph P

    2009-03-15

    A sensitive high performance liquid chromatography method (HPLC) has been developed for the quantification of doxorubicin in mouse plasma and tissues. Samples of serum or tissue homogenates, 20 microl, were analyzed following a single step protein precipitation using perchloric acid (35%, v/v). Doxorubicin was separated from the internal standard, daunorubicin, on a Zorbax 300SB C(18) column at 35 degrees C. Mobile phase was comprised of acetonitrile and water (25:75) containing 0.1% triethylamine, and was adjusted to pH 3 with phosphoric acid. Peaks eluting from the column were detected with a fluorescence detector with excitation and emission wavelengths of 480 and 560 nm, respectively. Standard curves were linear in the range 5-1000 ng/ml, and correlation coefficients were typically greater than 0.999. Intra-assay recoveries ranged from 94.7 to 99.9%, and inter-assay recoveries were in the range of 95.2-101%. The associated coefficient of variation (CV) was less than 10% in all cases. The method was successfully applied to investigate doxorubicin plasma pharmacokinetics and tissue distribution in athymic Fox(nu) mice.

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

    PubMed

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

    2014-03-25

    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.

  14. 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.

  15. 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.

  16. Chemometric processing of second-order liquid chromatographic data with UV-vis and fluorescence detection. A comparison of multivariate curve resolution and parallel factor analysis 2.

    PubMed

    Bortolato, Santiago A; Olivieri, Alejandro C

    2014-09-01

    Second-order liquid chromatographic data with multivariate spectral (UV-vis or fluorescence) detection usually show changes in elution time profiles from sample to sample, causing a loss of trilinearity in the data. In order to analyze them with an appropriate model, the latter should permit a given component to have different time profiles in different samples. Two popular models in this regard are multivariate curve resolution-alternating least-squares (MCR-ALS) and parallel factor analysis 2 (PARAFAC2). The conditions to be fulfilled for successful application of the latter model are discussed on the basis of simple chromatographic concepts. An exhaustive analysis of the multivariate calibration models is carried out, employing both simulated and experimental chromatographic data sets. The latter involve the quantitation of benzimidazolic and carbamate pesticides in fruit and juice samples using liquid chromatography with diode array detection, and of polycyclic aromatic hydrocarbons in water samples, in both cases in the presence of potential interferents using liquid chromatography with fluorescence spectral detection, thereby achieving the second-order advantage. The overall results seem to favor MCR-ALS over PARAFAC2, especially in the presence of potential interferents.

  17. Calculation of Retention Time Tolerance Windows with Absolute Confidence from Shared Liquid Chromatographic Retention Data

    PubMed Central

    Boswell, Paul G.; Abate-Pella, Daniel; Hewitt, Joshua T.

    2015-01-01

    Compound identification by liquid chromatography-mass spectrometry (LC-MS) is a tedious process, mainly because authentic standards must be run on a user’s system to be able to confidently reject a potential identity from its retention time and mass spectral properties. Instead, it would be preferable to use shared retention time/index data to narrow down the identity, but shared data cannot be used to reject candidates with an absolute level of confidence because the data are strongly affected by differences between HPLC systems and experimental conditions. However, a technique called “retention projection” was recently shown to account for many of the differences. In this manuscript, we discuss an approach to calculate appropriate retention time tolerance windows for projected retention times, potentially making it possible to exclude candidates with an absolute level of confidence, without needing to have authentic standards of each candidate on hand. In a range of multi-segment gradients and flow rates run among seven different labs, the new approach calculated tolerance windows that were significantly more appropriate for each retention projection than global tolerance windows calculated for retention projections or linear retention indices. Though there were still some small differences between the labs that evidently were not taken into account, the calculated tolerance windows only needed to be relaxed by 50% to make them appropriate for all labs. Even then, 42% of the tolerance windows calculated in this study without standards were narrower than those required by WADA for positive identification, where standards must be run contemporaneously. PMID:26292624

  18. Preparation and chromatographic evaluation of a cysteine-bonded zwitterionic hydrophilic interaction liquid chromatography stationary phase.

    PubMed

    Shen, Aijin; Guo, Zhimou; Cai, Xiaoming; Xue, Xingya; Liang, Xinmiao

    2012-03-01

    orthogonality between Click TE-Cys and TSK Amide-80 system was 21.4%, i.e. the selectivity was similar but slightly different from each other. The successful separation of protein digests indicated the great potential of Click TE-Cys stationary phase in the separation of complex samples and applicability in two-dimensional liquid chromatography (2D-LC).

  19. The selection of suitable columns for a reversed-phase liquid chromatographic separation of beta-lactam antibiotics and related substances via chromatographic column parameters.

    PubMed

    Zhang, Wei-qing; Hu, Qiu-xin; Zhang, Xia; Li, Ya-ping; Wang, Ming-juan; Hu, Chang-qin

    2014-01-01

    The selection of RP-LC columns suitable for a particular analysis in official compendia is difficult as only a general description of the stationary phase in the description of a LC method is given. General methods to characterize RP-LC columns often assume that each of the column parameters is equally important. This can cause the user to select columns inappropriate for particular analyses. This paper focuses on the relationship between the critical peak pairs and the column parameters (H, S, A, B, and C) in the Snyder/Dolan column characterization methodology to find the key parameters influencing real separations. Some varieties of β-lactam antibiotics and their related compounds were used as test compounds. We found column parameter A to be the most important factor affecting their separation. Parameters B and C also played an important role in some separation processes. This indicated that the hydrogen bonding of column and solute can directly affect the separation of β-lactam antibiotics. Choosing columns for which column parameter A is near 0.1 can facilitate the ideal separations of impurities from β-lactam antibiotics. The most suitable column for any common pharmaceutical analysis could be selected easily if the key column parameters would be given in the description of the chromatographic method. For these reasons, key column parameters should be listed in the monographs of official compendia.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. High-performance liquid chromatographic separation of paclitaxel intermediate phenylisoserine derivatives on macrocyclic glycopeptide and cyclofructan-based chiral stationary phases.

    PubMed

    Ilisz, István; Grecsó, Nóra; Forró, Enikő; Fülöp, Ferenc; Armstrong, Daniel W; Péter, Antal

    2015-10-10

    High-performance liquid chromatographic methods were developed for the separation of enantiomers of four unnatural paclitaxel precursor phenylisoserine analogs on chiral stationary phases containing macrocyclic glycopeptides and cyclofructans as chiral selectors. The effects of the mobile phase composition, the nature and concentration of different mobile phase additives (alcohols, amines and acids) in different chromatographic modes, temperature and the structures of the analytes on the separations were investigated. Separations were carried out at constant mobile phase compositions in the temperature range 10-50°C on macrocyclic antibiotic-based and 5-35°C on cyclofructan-based columns and the changes in enthalpy, Δ(ΔH°), entropy, Δ(ΔS°), and free energy, Δ(ΔG°), were calculated. The elution sequence was determined in most cases; no general rule could be observed.

  6. Fractionalized Fermi liquid on the surface of a topological Kondo insulator

    NASA Astrophysics Data System (ADS)

    Thomson, Alex; Sachdev, Subir

    2016-03-01

    We argue that topological Kondo insulators can also have "intrinsic" topological order associated with fractionalized excitations on their surfaces. The hybridization between the local moments and conduction electrons can weaken near the surface, and this enables the local moments to form spin liquids. This coexists with the conduction electron surface states, realizing a surface fractionalized Fermi liquid. We present mean-field solutions of a Kondo-Heisenberg model in two spatial dimensions which display such surfaces.

  7. Fractional Wigner Crystal in the Helical Luttinger Liquid.

    PubMed

    Traverso Ziani, N; Crépin, F; Trauzettel, B

    2015-11-13

    The properties of the strongly interacting edge states of two dimensional topological insulators in the presence of two-particle backscattering are investigated. We find an anomalous behavior of the density-density correlation functions, which show oscillations that are neither of Friedel nor of Wigner type: they, instead, represent a Wigner crystal of fermions of fractional charge e/2, with e the electron charge. By studying the Fermi operator, we demonstrate that the state characterized by such fractional oscillations still bears the signatures of spin-momentum locking. Finally, we compare the spin-spin correlation functions and the density-density correlation functions to argue that the fractional Wigner crystal is characterized by a nontrivial spin texture.

  8. Isolation and recovery of selected polybrominated diphenyl ethers from human serum and sheep serum: coupling reversed-phase solid-phase disk extraction and liquid-liquid extraction techniques with a capillary gas chromatographic electron capture negative ion mass spectrometric determinative technique.

    PubMed

    Loconto, Paul R; Isenga, David; O'Keefe, Michael; Knottnerus, Mark

    2008-01-01

    Polybrominated diphenyl ethers (PBDEs) are isolated and recovered with acceptable percent recoveries from human serum via liquid-liquid extraction and column chromatographic cleanup and fractionation with quantitation using capillary gas chromatography-mass spectrometry with electron capture negative ion and selected ion monitoring. PBDEs are found in unspiked serum. An alternative sample preparation approach is developed using sheep serum that utilizes a formic acid pre-treatment followed by reversed-phase solid-phase disk extraction and normal-phase solid-phase cleanup using acidified silica gel that yields>50% recoveries. When these percent recoveries are combined with a minimized phase ratio for human serum and very low instrument detection limits, method detection limits below 500 parts-per-trillion are realized.

  9. High performance liquid chromatographic-mass spectrometric assay for the quantitation of BMS-204352 in dog K(3)EDTA plasma.

    PubMed

    Yao, Ming; Mantha, Subbarao; Shah, Vinod R; Vachharajani, Nimish N; Arnold, Mark E; Pursley, Janice M; Srinivas, Nuggehally R

    2002-05-01

    A high performance liquid chromatographic-mass spectrometric (LC/MS) assay was developed and validated for the determination of BMS-204352 in dog K(3)EDTA plasma. A 0.5 mL aliquot of control plasma was spiked with BMS-204352 and internal standard (IS) and buffered with 1 mL of 5 mM ammonium acetate. The mixture was then extracted with 3 mL of toluene. After separation and evaporation of the organic phase to dryness using nitrogen at 40 degrees C, the residue was reconstituted in the mobile phase and 25 microL of the sample were injected onto a Hypersil C(18) column (2 x 50 mm; 3 microm) at a flow rate of 0.5 mL/min. The mobile phase was consisted of two solvent mixtures (A and B). Solvent A was composed of 5 mM ammonium acetate and 0.1% triethylamine in 75:25 v/v water:methanol, pH adjusted to 5.5 with glacial acetic acid, and solvent B was 5 mM ammonium acetate in methanol. A linear gradient system was used to elute the analytes. The mass spectrometer was programmed to admit the de-protonated molecules at m/z 352.7 (IS) and m/z 357.9 (BMS-204352). Standard curves of BMS-204352 were linear (r(2) > or = 0.998) over the concentration range of 0.5-1000 ng/mL. The mean predicted quality control (QC) concentrations deviated less than 5.1% from the corresponding nominal values (ie 4, 80, 400 and 2000 ng/mL); the within- and between-assay precision of the assay were within 5.5% relative standard deviation. Stability of BMS-204352 was confirmed after at least three freeze/thaw cycles and BMS-204532 was stable in dog plasma when stored frozen at or below -20 degrees C for at least 16 weeks in spiked QC samples and for at least 4 1/2 weeks for in vivo study samples. BMS-204352 and IS were stable in the injection solvent at room temperature for at least 24 h. The assay was applied to delineate the pharmacokinetic disposition of BMS-204352 in dogs following a single intravenous dose administration. In conclusion, the assay is accurate, precise, specific, sensitive and

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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

    2016-04-30

    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.

  15. A validated high performance liquid chromatograph-photodiode array method for simultaneous determination of 10 bioactive components in compound hongdoushan capsule

    PubMed Central

    Zhu, Liancai; Yang, Xian; Tan, Jun; Wang, Bochu; Zhang, Xue

    2014-01-01

    Background: The compound Hongdoushan capsule (CHC) is widely known as compound herbal preparation and is often used to treat ovarian cancer and breast cancer, and to enhance the body immunity, etc., in clinical practice. Objective: To determine simultaneously 10 bioactive components from CHC, namely glycyrrhetinic acid, liquiritin, glycyrrhizin, baccatin III, 10-deacetylbaccatin III, cephalomannine, taxol, ginsenoside Rg1, ginsenoside Re, and ginsenoside Rb1. Materials and Methods: A high performance liquid chromatograph method coupled with photodiode array detector was developed and validated for the 1st time. Chromatographic analysis was performed on a SHIMADZU C18 by utilizing a gradient elution program. The mobile phase was acetonitrile (A)-water (B) at a flow rate of 0.8 mL/min. Results: The calibration curve was linear over the investigated concentration ranges with the values of r2 higher than 0.9993 for all the 10 bioactive components. The average recovery rates range from 98.4% to 100.5% with relative standard deviations ≤2.9%. The developed method was successfully applied to analyze 10 compounds in six CHC samples from different batches. In addition, the herbal sources of 32 chromatographic peaks were identified through comparative studying on chromatograms of standard, the respective extracts of Hongdoushan, RenShen, GanCao, and CHC. Conclusion: All the results imply that the accurate and reproducible method developed has high separation rate and enables the determination of 10 bioactive components in a single run for the quality control of CHC. PMID:24696551

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. Development and validation of a stability-indicating high performance liquid chromatographic (HPLC) assay for biperiden in bulk form and pharmaceutical dosage forms.

    PubMed

    Mohammadi, A; Mehramizi, A; Moghaddam, F Aghaee; Jabarian, L Erfani; Pourfarzib, M; Kashani, H N

    2007-07-01

    Current compendial (USP) methods of assay for the analysis of biperiden in bulk form and pharmaceutical dosage forms involve the use of titrimetric and spectrophotometric procedures, respectively. These are non-selective and non-stability-indicating techniques. In this work, a stability-indicating high performance liquid chromatographic assay procedure has been developed and validated for biperiden. The liquid chromatographic separation was achieved isocratically on a symmetry C8 column (150 mm x 3.9 mm i.d., 5 microm particle size) using a mobile phase containing methanol-buffer (50:50, v/v, pH 2.50) at a flow rate of 1 ml/min and UV detection at 205 nm. The buffer was composed of sodium dihydrogen phosphate (50 mM) and 1-heptanesulfonic acid sodium salt (5 mM). The method was linear over the concentration range of 0.5-25 microg/ml (r=0.9998) with a limit of detection and quantitation 0.03 and 0.1 microg/ml, respectively. The method has the requisite accuracy, selectivity, sensitivity and precision to assay biperiden in bulk form and pharmaceutical dosage forms. Degradation products resulting from the stress studies did not interfere with the detection of biperiden and the assay is thus stability-indicating.

  1. Concerted derivatization and concentration method with dispersive liquid-liquid microextraction for liquid chromatographic analysis of 5-hydroxyindoles in human serum.

    PubMed

    Hayama, Tadashi; Yabuuchi, Yurika; Iwamatsu, Tomomi; Tamashima, Erina; Kawami, Yusuke; Itoyama, Miki; Yoshida, Hideyuki; Yamaguchi, Masatoshi; Nohta, Hitoshi

    2013-12-15

    We developed a concerted derivatization and concentration method based on dispersive liquid-liquid microextraction (DLLME) for the liquid chromatography (LC) determination of 5-hydroxyindoles (5-HIs; serotonin, 5-hydroxyindole-3-acetic acid, N-acetylserotonin, and 5-hydroxytryptohol). Concerted derivatization and concentration could be affected by adding a mixture of an ionic liquid (1-hexyl-3-methylimidazolium hexafluorophosphate, extraction solvent), methanol (disperser), and water containing fluorescence derivatization reagents [benzylamine and potassium hexacyanoferrate(III)] into the sample. The resulting sedimented phase was injected into a reversed-phase LC column using a mixture of acetonitrile and 250 mM acetate buffer (pH 4.3) as the mobile phase for gradient elution, and the derivatives obtained were fluorometrically detected at excitation and emission wavelengths of 345 nm and 452 nm, respectively. The derivatization (reagent concentrations and pH) and extraction (extraction and disperser solvent type) conditions were optimized simultaneously. The limits of detection of the 5-HIs were in the range of 0.08-0.33 nM. The method was validated for 10 and 50 pmol/mL human serum levels, and the recovery of 5-HIs was between 66% and 98%, within a relative standard deviation of 9.5%. The proposed method is well suited for the highly sensitive analysis of trace amounts of 5-HIs in human serum samples. PMID:24209305

  2. 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.

  3. Non-invasive measurement of void fraction and liquid temperature in microchannel flow boiling

    NASA Astrophysics Data System (ADS)

    Fogg, David; David, Milnes; Goodson, Kenneth

    2009-04-01

    Past thermometry research for two-phase microfluidic systems made much progress regarding wall temperature distributions, yet the direct measurement of fluid temperature has received little attention. This paper uses a non-invasive two-dye/two-color fluorescent technique to capture fluid temperature along with local liquid fraction in a two-phase microflow generated by injecting air into a heated microchannel. The fluorescent emission of Rhodamine 110 and Rhodamine B, measured with photodiodes, is used to obtain local liquid temperature (±3°C) and void fraction (±2% full-scale) over a temperature range from 45 to 100°C. Arrays of these sensors can significantly expand the set of measurable flow parameters to include bubble/slug frequency, size, velocity, and growth rates in addition to mapping the local liquid temperature and void fraction.

  4. Fractional topological liquids with time-reversal symmetry and their lattice realization

    NASA Astrophysics Data System (ADS)

    Neupert, Titus; Santos, Luiz; Ryu, Shinsei; Chamon, Claudio; Mudry, Christopher

    2011-10-01

    We present a class of time-reversal-symmetric fractional topological liquid states in two dimensions that support fractionalized excitations. These are incompressible liquids made of electrons, for which the charge Hall conductance vanishes and the spin Hall conductance needs not be quantized. We then analyze the stability of edge states in these two-dimensional topological fluids against localization by disorder. We find a Z2 stability criterion for whether or not there exists a Kramers pair of edge modes that is robust against disorder. We also introduce an interacting electronic two-dimensional lattice model based on partially filled flattened bands of a Z2 topological band insulator, which we study using numerical exact diagonalization. We show evidence for instances of the fractional topological liquid phase as well as for a time-reversal symmetry broken phase with a quantized (charge) Hall conductance in the phase diagram for this model.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. Chromatographic background drift correction coupled with parallel factor analysis to resolve coelution problems in three-dimensional chromatographic data: quantification of eleven antibiotics in tap water samples by high-performance liquid chromatography coupled with a diode array detector.

    PubMed

    Yu, Yong-Jie; Wu, Hai-Long; Fu, Hai-Yan; Zhao, Juan; Li, Yuan-Na; Li, Shu-Fang; Kang, Chao; Yu, Ru-Qin

    2013-08-01

    Chromatographic background drift correction has been an important field of research in chromatographic analysis. In the present work, orthogonal spectral space projection for background drift correction of three-dimensional chromatographic data was described in detail and combined with parallel factor analysis (PARAFAC) to resolve overlapped chromatographic peaks and obtain the second-order advantage. This strategy was verified by simulated chromatographic data and afforded significant improvement in quantitative results. Finally, this strategy was successfully utilized to quantify eleven antibiotics in tap water samples. Compared with the traditional methodology of introducing excessive factors for the PARAFAC model to eliminate the effect of background drift, clear improvement in the quantitative performance of PARAFAC was observed after background drift correction by orthogonal spectral space projection.

  10. Synthesis and Characterization of Liquid Chromatographic Columns Containing the Immobilized Ligand Binding Domain of the Estrogen Related Receptor α and Estrogen Related Receptor γ

    PubMed Central

    Sanghvi, M.; Moaddel, R.; Frazier, C.; Wainer, I.W.

    2010-01-01

    The ligand binding domains of the estrogen related receptors, ERRα and ERRγ were covalently immobilized onto the surface of an aminopropyl silica liquid chromatography stationary phase to create the ERRα-silica and ERRγ-silica columns and onto the surface of open tubular capillaries to create the ERRα-OT and ERRγ-OT columns. The ERR-silica and ERR-OT columns were characterized using frontal chromatographic techniques with diethylstibesterol and the binding affinities, Kd values, to the immobilized receptors were consistent with the values obtained by a radioligand binding assay. The ERRγ-silica column was also characterized using non-linear chromatographic techniques using a series of tamoxifen derivatives. The relative Kd values obtained for the derivatives were consistent with the relative ability of the compounds to inhibit the cellular proliferation of the human-derived T98G glioma cell line, expressed as IC50 values. The results indicate that the columns containing immobilized ERRα and ERRγ can be created and used to characterize the binding of compounds to the immobilized receptors and that the relative retention of compounds on these columns reflects the magnitude of their inhibitory activity. PMID:20542653

  11. Stability-indicating liquid chromatographic method for determination of saxagliptin and structure elucidation of the major degradation products using LC-MS.

    PubMed

    Abdel-Ghany, Maha F; Abdel-Aziz, Omar; Ayad, Miriam F; Tadros, Mariam M

    2015-04-01

    A new, simple, selective, reproducible and sensitive stability-indicating liquid chromatographic method was developed and subsequently validated for the determination of saxagliptin (SXG). SXG was subjected to oxidation, thermal, acid hydrolysis, alkali hydrolysis and photodegradation according to ICH guidelines. The major degradation products were separated from the pure drug and the proposed structures' elucidation was performed, using an LC-MS technique. Isocratic chromatographic elution was achieved on a Symmetry(®) C18 column (150 × 4.6 mm, 5 µm), using a mobile phase of potassium dihydrogen phosphate buffer (pH 4.6)-acetonitrile-methanol (40 : 30 : 30, v/v/v) at a flow rate of 1 mL min(-1) with UV detection at 208 nm. Linearity, accuracy and precision were found to be acceptable over the concentration range of 25-400 µg mL(-1). All the results were statistically compared with the reference method, using one-way analysis of variance. The developed method was validated and proved to be specific and accurate for quality control of SXG in pharmaceutical dosage form.

  12. Development and validation of a simple stability-indicating high performance liquid chromatographic method for the determination of miconazole nitrate in bulk and cream formulations.

    PubMed

    De Zan, María M; Cámara, María S; Robles, Juan C; Kergaravat, Silvina V; Goicoechea, Héctor C

    2009-08-15

    A simple and stability-indicating high performance liquid chromatographic method was developed and validated for the determination of miconazole nitrate in bulk and cream preparations. The extraction step for cream samples consisted in a warming, cooling and centrifugation procedure that assures the elimination of the lipophilic matrix component, in order to avoid further precipitation in the chromatographic system. Separation was achieved on a ZORBAX Eclipse XDB - C18 (4.6 mm x 150 mm, 5 microm particle size) column, using a mobile phase consisting of water, methanol and acetonitrile, in a flow and solvent gradient elution for 15 min. The column was maintained at 25 degrees C and 10 microL of solutions were injected. UV detection was performed at 232 nm, although employment of a diode array detector allowed selectivity confirmation by peak purity evaluation. The method was validated reaching satisfactory results for selectivity, precision and accuracy. Degradation products in naturally aged samples could be simultaneously evaluated, without interferences in the quantitative analysis.

  13. 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

  14. Development and validation of a stability-indicating high performance liquid chromatographic (HPLC) method for the determination of related substances of micafungin sodium in drug substances.

    PubMed

    Zhu, Shengsheng; Meng, Xiang; Su, Xin; Luo, Yongwei; Sun, Zuyue

    2013-10-24

    An isocratic, sensitive and stability-indicating high performance liquid chromatographic (HPLC) method for separation and determination of the related substances of micafungin sodium was developed. The chromatographic separation was achieved on Agilent Zorbax SB-C18 column (250 × 4.6 mm, 5 μm). Forced degradation study confirmed that the newly developed method was specific and selective to the degradation products. The performance of the method was validated according to the present ICH guidelines for specificity, linearity, accuracy, precision and robustness. Regression analysis showed correlation coefficient value greater than 0.999 for micafungin sodium and its six impurities. Limit of detection of impurities was in the range of 0.006%-0.013% indicating the high sensitivity of the newly developed method. Accuracy of the method was established based on the recovery obtained between 98.2% and 102.0% for all impurities. RSD obtained for the repeatability and intermediate precision experiments, was less than 1.0%. The method was successfully applied to quantify related substances of micafungin sodium in bulk drugs.

  15. Development and Validation of a Stability-Indicating High Performance Liquid Chromatographic (HPLC) Method for the Determination of Related Substances of Micafungin Sodium in Drug Substances

    PubMed Central

    Zhu, Shengsheng; Meng, Xiang; Su, Xin; Luo, Yongwei; Sun, Zuyue

    2013-01-01

    An isocratic, sensitive and stability-indicating high performance liquid chromatographic (HPLC) method for separation and determination of the related substances of micafungin sodium was developed. The chromatographic separation was achieved on Agilent Zorbax SB-C18 column (250 × 4.6 mm, 5 μm). Forced degradation study confirmed that the newly developed method was specific and selective to the degradation products. The performance of the method was validated according to the present ICH guidelines for specificity, linearity, accuracy, precision and robustness. Regression analysis showed correlation coefficient value greater than 0.999 for micafungin sodium and its six impurities. Limit of detection of impurities was in the range of 0.006%–0.013% indicating the high sensitivity of the newly developed method. Accuracy of the method was established based on the recovery obtained between 98.2% and 102.0% for all impurities. RSD obtained for the repeatability and intermediate precision experiments, was less than 1.0%. The method was successfully applied to quantify related substances of micafungin sodium in bulk drugs. PMID:24284389

  16. Supercharging Reagent for Enhanced Liquid Chromatographic Separation and Charging of Sialylated and High-Molecular-Weight Glycopeptides for NanoHPLC-ESI-MS/MS Analysis.

    PubMed

    Lin, Chia-Wei; Haeuptle, Micha A; Aebi, Markus

    2016-09-01

    Recent developments in proteomic techniques have led to the development of mass spectrometry (MS)-based methods to characterize site-specific glycosylation of proteins. However, appropriate analytical tools to characterize acidic and high-molecular-weight (hMW) glycopeptides are still lacking. In this study, we demonstrate that the addition of supercharging reagent, m-nitrobenzyl alcohol (m-NBA), into mobile phases greatly facilitates the analysis of acidic and hMW glycopeptides. Using commercial glycoproteins, we demonstrated that in the presence of m-NBA the charge state of sialylated glycopeptides increased and the chromatographic separation of neutral and acidic glycopeptides revealed a remarkable improvement. Next, we applied this system to the characterization of a glycoconjugate vaccine candidate consisting of a genetically detoxified exotoxin A of Pseudomonas aeruginosa covalently linked to Shigella flexneri type 2a O-antigen (Sf2E) produced by engineered Escherichia coli. The addition of m-NBA, allowed us to identify peptides with glycan chains of unprecedented size, up to 20 repeat units (98 monosaccharides). Our results indicated that incorporation of m-NBA into reversed-phase liquid chromatography (LC) solvents improves sensitivity, charging, and chromatographic resolution for acidic and hMW glycopeptides. PMID:27487254

  17. 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

  18. Supercharging Reagent for Enhanced Liquid Chromatographic Separation and Charging of Sialylated and High-Molecular-Weight Glycopeptides for NanoHPLC-ESI-MS/MS Analysis.

    PubMed

    Lin, Chia-Wei; Haeuptle, Micha A; Aebi, Markus

    2016-09-01

    Recent developments in proteomic techniques have led to the development of mass spectrometry (MS)-based methods to characterize site-specific glycosylation of proteins. However, appropriate analytical tools to characterize acidic and high-molecular-weight (hMW) glycopeptides are still lacking. In this study, we demonstrate that the addition of supercharging reagent, m-nitrobenzyl alcohol (m-NBA), into mobile phases greatly facilitates the analysis of acidic and hMW glycopeptides. Using commercial glycoproteins, we demonstrated that in the presence of m-NBA the charge state of sialylated glycopeptides increased and the chromatographic separation of neutral and acidic glycopeptides revealed a remarkable improvement. Next, we applied this system to the characterization of a glycoconjugate vaccine candidate consisting of a genetically detoxified exotoxin A of Pseudomonas aeruginosa covalently linked to Shigella flexneri type 2a O-antigen (Sf2E) produced by engineered Escherichia coli. The addition of m-NBA, allowed us to identify peptides with glycan chains of unprecedented size, up to 20 repeat units (98 monosaccharides). Our results indicated that incorporation of m-NBA into reversed-phase liquid chromatography (LC) solvents improves sensitivity, charging, and chromatographic resolution for acidic and hMW glycopeptides.

  19. 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.

  20. 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.

  1. Selection of reversed-phase liquid chromatographic columns with diverse selectivity towards the potential separation of impurities in drugs.

    PubMed

    Van Gyseghem, E; Jimidar, M; Sneyers, R; Redlich, D; Verhoeven, E; Massart, D L; Vander Heyden, Y

    2004-07-01

    To select appropriate stationary phases from the continuously expanding supply of potentially suitable HPLC columns, the properties of 28 frequently applied stationary phases were determined by measuring several chromatographic parameters. From these results, based on chromatographic expertise, eight stationary phases with different properties and selectivities were selected. The aim of this study is to apply chemometric tools to evaluate the initially selected set of columns, i.e. a more systematic approach for making such a selection is examined. Starting from the information obtained on the 28 stationary phases, the re-evaluation was performed independently based on the chemometric techniques Pareto-optimality, principal component analysis (PCA), and Derringer's desirability functions. The aim was to select a set of efficient columns exhibiting large selectivity differences. The chemometrically selected stationary phases were divided in groups based on hydrophobicity, a critical retention-determining property in reversed-phase chromatography. This allowed to further reducing the selection to three columns. It is demonstrated that the selection by the chemometric approaches in general is fairly comparable with the initial selection.

  2. 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

  3. Rapid fractionation of collagen chains and peptides by high-performance liquid chromatography.

    PubMed

    Bateman, J F; Mascara, T; Chan, D; Cole, W G

    1986-04-01

    A strategy was developed, using a Pharmacia Fast Protein Liquid chromatography (FPLC) system, for the rapid preparation of the alpha-chains, cyanogen bromide peptides and tryptic peptides of type I collagen obtained from tissues and cultured fibroblasts. Collagen alpha-chains were prepared using a C18 PEP-RPC reverse-phase column and volatile solvents. Preliminary Superose 6 gel permeation chromatography was used to separate the crosslinked beta- and gamma-chains from the alpha-chains of tissue collagen samples. A Mono S cation-exchange column was used to resolve all of the major type I collagen cyanogen bromide peptides including the alpha 1(I)CB7 and CB8 peptides, which have not been well resolved by previously published methods. Collagen tryptic peptides were chromatographed on the PEP-RPC reverse-phase column.

  4. 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

  5. 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.

  6. Fractionalized charge excitations in a spin liquid on partially filled pyrochlore lattices.

    PubMed

    Chen, Gang; Kee, Hae-Young; Kim, Yong Baek

    2014-11-01

    We study the Mott transition from a metal to cluster Mott insulators in the 1/4- and 1/8-filled pyrochlore lattice systems [corrected]. It is shown that such Mott transitions can arise due to charge localization in clusters or in tetrahedron units, driven by the nearest-neighbor repulsive interaction. The resulting cluster Mott insulator is a quantum spin liquid with a spinon Fermi surface, but at the same time a novel fractionalized charge liquid with charge excitations carrying half the electron charge. There exist two emergent U(1) gauge fields or "photons" that mediate interactions between spinons and charge excitations, and between fractionalized charge excitations themselves, respectively. In particular, it is suggested that the emergent photons associated with the fractionalized charge excitations can be measured in x-ray scattering experiments. Various other experimental signatures of the exotic cluster Mott insulator are discussed in light of candidate materials with partially filled bands on the pyrochlore lattice.

  7. 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

  8. 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.

  9. 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

  10. High performance liquid chromatographic separation and pH-dependent electrochemical properties of pyrroloquinoline quinone and three closely related isomeric analogues.

    PubMed

    Zhang, Z; Tillekeratne, L M; Kirchhoff, J R; Hudson, R A

    1995-07-01

    Pyrroloquinoline quinone 1 (PQQ, methoxatin, 4,5-dihydro-4,5-dioxo-1H-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylic acid) is a novel coenzyme. Closely related isomeric analogues of PQQ may be formed in nature and may possess PQQ-like functions. Here, the electrochemical pH-dependent properties and the high performance liquid chromatographic (HPLC) separation protocols are reported for three major isomeric PQQ analogues likely to be formed in nature. The electrochemical data (cyclic voltammetry) provided the pKas of the five ionizable groups in each isomeric PQQ. The HPLC protocols provide the means of investigating the formation of PQQ and the PQQ isomers reported here during the normal turnover of eukaryotic amine oxidases containing integral topaquinone residues, as well as from direct enzyme-mediated reactions which remain to be characterized.

  11. Isocratic non-aqueous reversed-phase high-performance liquid chromatographic separation of capsanthin and capsorubin in red peppers (Capsicum annuum L.), paprika and oleoresin.

    PubMed

    Weissenberg, M; Schaeffler, I; Menagem, E; Barzilai, M; Levy, A

    1997-01-01

    A simple, rapid high-performance liquid chromatography method has been devised in order to separate and quantify the xanthophylls capsorubin and capasanthin present in red pepper (Capsicum annuum L.) fruits and preparations made from them (paprika and oleoresin). A reversed-phase isocratic non-aqueous system allows the separation of xanthophylls within a few minutes, with detection at 450 nm, using methyl red as internal standard to locate the various carotenoids and xanthophylls found in plant extracts. The selection of extraction solvents, mild saponification conditions, and chromatographic features is evaluated and discussed. The method is proposed for rapid screening of large plant populations, plant selection, as well as for paprika products and oleoresin, and also for nutrition and quality control studies.

  12. A liquid chromatographic-tandem mass spectrometric method for the determination of YM466, a novel Factor Xa inhibitor, in rat plasma.

    PubMed

    Mano, Yuji; Usui, Takashi; Kamimura, Hidetaka

    2004-11-19

    A sensitive and selective method for the determination of YM466, a novel Factor Xa inhibitor, in rat plasma was developed and validated using liquid chromatography-mass spectrometry with electrospray ionization. Plasma samples were pretreated by solid-phase extraction and chromatographed on a C18 column (75 mm x 4.6 mm i.d.) with a mobile phase consisting of 0.1% formic acid-methanol (70:30 (v/v)), and detected using selected reaction monitoring in the positive-ion mode. The lower limit of quantification was 0.4 ng/ml, and good precision and accuracy were achieved. The validated method allowed analysis of samples for the determination of pharmacokinetic profiles of YM466 in rats. PMID:15533684

  13. Liquid chromatographic determination of the glycoalkaloids alpha-solanine and alpha-chaconine in potato tubers: NMKL Interlaboratory Study. Nordic Committee on Food Analysis.

    PubMed

    Hellenäs, K E; Branzell, C

    1997-01-01

    Twelve laboratories participated in a collaborative study to evaluate precision parameters of a liquid chromatographic method for analysis of the glycoalkaloids alpha-solanine and alpha-chaconine in potato tubers. Samples consisted of frozen potato tuber homogenates distributed as 3 blind duplicates and 3 split-level pairs. The analytical method included aqueous extraction, workup on disposable solid-phase extraction cartridges, and reversed-phase chromatography with photometric detection at 202 nm. Results for alpha-solanine and alpha-chaconine were received from 10 and 9 laboratories, respectively. Relative standard deviations for reproducibility for alpha-solanine and alpha-chaconine were similar, ranging from 8 to 13% in the applied concentration range of 12 to 260 mg/kg fresh weight.

  14. Development and validation of a liquid chromatographic method for monitoring of process-related synthetic organic impurities of profenofos in technical products.

    PubMed

    Nageswara Rao, R; Naga Raju, D; Venkateswarlu, N; Vittal Rao, B; Parvathi, N; Manjula, A; Reddy, G N; Gawali, P B; Sreekanth, M; Nageswara Rao, P

    2003-09-01

    A simple and rapid reversed-phase high-performance liquid chromatographic method for the monitoring of process-related synthetic organic impurities of profenofos (PFS) is developed. Impurities are separated and determined on a reversed-phase Hypersil C(18) column using gradient elution of 50 mM ammonium formate buffer-acetonitrile as a mobile phase and detection at 230 nm at ambient temperature. The method is validated with respect to accuracy, precision, linearity, and limits of detection and quantitation. The method is found to be suitable not only for monitoring the reactions involved in the process development of PFS, but also quality assurance, as it can detect impurities at the level of 1.5 x 10(-8) g. PMID:14558934

  15. 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

  16. 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

  17. 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

  18. 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.

  19. Application of liquid chromatographic/tandem mass spectrometric method to a urinary excretion study of subutinib and active metabolite in human urine.

    PubMed

    Ding, Li-kun; Yang, Lin; Gao, Xiao-hua; Chen, Su-ning; Jia, Na; Li, Xue-qing; Zhou, Lun; Hang, Tai-jun; Wen, Ai-dong

    2016-04-01

    A novel and selective liquid chromatographic-mass spectrometric method (LC-MS/MS) has been established and validated for simultaneous determination of subutinib and active metabolite in human urine. Urine samples were extracted by liquid-liquid extraction with ethyl acetate and separated on a Wondasil C18 (150 × 2.1 mm, 3.5 µm), with methanol-0.2% formic acid solution (73:27, v/v) as mobile phase at flow rate of 0.2 mL/min. The linear range was 0.5000-200.0 ng/mL for subutinib and active metabolite, with a lower limit of quantitation of 0.5000 ng/mL. Intra- and inter-run precisions were all <11.8 and 14.3%, and the accuracies were all <4.5 and 5.4%, with the extraction recoveries 88.8-97.5 and 93.8-99.4% for the two analytes, respectively. The carryover values were all <15% for the two anayltes. The method was successfully applied to study urinary excretion of subutinib and active metabolite in human after oral administration of subutinib maleate capsules in fed and fasting states.

  20. 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

  1. 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.

  2. 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.

  3. Method for the chromatographic separation of cations from aqueous samples

    DOEpatents

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

    1997-07-29

    An extraction chromatographic material is described for extracting metal cations from a liquid stream. The extraction chromatographic material is prepared by adsorbing a diesterified methanediphosphonic acid on an inert particulate support. 7 figs.

  4. Method for the chromatographic separation of cations from aqueous samples

    DOEpatents

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

    1998-12-22

    An extraction chromatographic material is described for extracting metal cations from a liquid stream. The extraction chromatographic material is prepared by adsorbing a diesterified methane-diphosphonic acid on an inert particulate support. 7 figs.

  5. Method for the chromatographic separation of cations from aqueous samples

    DOEpatents

    Horwitz, E. Philip; Chiarizia, Renato; Dietz, Mark L.

    1998-12-22

    An extraction chromatographic material for extracting metal cations from a liquid stream. The extraction chromatographic material is prepared by adsorbing a diesterified methanediphosphonic acid on an inert particulate support.

  6. 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.

  7. 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

  8. Superficially porous particles vs. fully porous particles for bonded high performance liquid chromatographic chiral stationary phases: isopropyl cyclofructan 6.

    PubMed

    Spudeit, Daniel A; Dolzan, Maressa D; Breitbach, Zachary S; Barber, William E; Micke, Gustavo A; Armstrong, Daniel W

    2014-10-10

    This work reports a comparison of HPLC separations of enantiomers with chiral stationary phases (CSPs) prepared by chemically bonding cyclofructan-6, functionalized with isopropyl carbamate groups on fully and superficially porous particles (SPPs). The chromatographic performance of the superficially porous CSP based column was compared with columns packed with 5 μm and 3 μm fully porous particles (FPPs). At a flow rate of 3.0 mL/min the number of plates on column afforded by the SPP column was ∼7× greater than the number of plates on column (same length) obtained when using the 5 μm FPP based column. The flow rate providing the highest efficiency separation was ∼1.0 mL/min for the SPP column while it was ∼0.5 mL/min for both FPP columns. It was found that the selectivity and resolution of the separations were comparable between fully porous and superficially porous based columns (under constant mobile phase conditions), even though the SPP column contained lower absolute amounts of chiral selector. When tested under constant retention conditions, the SPP based CSP greatly improved resolution compared to the FPP based columns. At high flow rates the efficiency gained by using superficially porous CSP was accentuated. The advantages of columns based on SPPs become more obvious from the viewpoint of plate numbers and resolution per analysis time.

  9. High-pressure liquid chromatographic assay of theophylline in dog feces following oral administration of sustained-release products.

    PubMed

    Chow, A T; Meek, P D; Jusko, W J

    1993-09-01

    A solid-phase-extraction reversed-phase HPLC assay is described for the determination of theophylline embedded in dog feces as powder, sustained-release tablets, or capsules. The feces is extracted with 5% isopropyl alcohol in chloroform in the presence of beta-hydroxypropyl-theophylline as the internal standard. Separation and quantitation are achieved with a C18 analytical column. UV absorbance is monitored at 280 nm. Recovery of theophylline was > 50%. The assay is linear between 10 and 400 mg amounts of theophylline in 50 g of feces. Inter- and intraday coefficients of variation of the chromatographic assay were < 3%, and the extraction procedure was highly reproducible with coefficients of variation of < 10% at amounts of drug from 10 to 400 mg. By keeping the stool/solvent extraction ratio constant, the method is equally effective in extracting theophylline from different sizes of stool samples (50 versus 200 g of stool). The assay was applied to evaluate the theophylline content in feces following oral administration of the drug to dogs as tablet (Theo-Dur) and capsule (Slo-Bid) dosage forms. The resulting fecal recovery values of each product were inversely related to the corresponding bioavailability values obtained from the literature.

  10. Residual biogas potential from the storage tanks of non-separated digestate and digested liquid fraction.

    PubMed

    Gioelli, F; Dinuccio, E; Balsari, P

    2011-11-01

    Biogas plants daily produce enormous volumes of digestate that can be handled in its raw form or after mechanical separation. In Italy, effluents are usually stored within aboveground, uncovered tanks, which make them potential emitters of biogas into the atmosphere. The purpose of this study was to estimate the amount of biogas emitted to the atmosphere during the storage phase of non-separated digestate and digested liquid fraction. The trials were performed at two northwest Italy 1 MWel. biogas plants. A floating system for the residual biogas recovery, and a set of three wind tunnels for NH3 emission measurement were used. The experiment demonstrated significant loss to the atmosphere for each of the gases; specifically, on average, 19.5 and 7.90 N m3 biogas MWhel.(-1) were emitted daily from the storage tanks of non-separated digestate and digested liquid fraction, respectively.

  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. 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.

  13. Reversed-phase ion-pair liquid chromatographic determination of chlorophacinone and diphacinone in steam-rolled oat baits and steam-rolled oat/wax baits.

    PubMed

    Primus, T M; Griffin, D L; Volz, S A; Johnston, J J

    1998-01-01

    A reversed-phase ion-pair liquid chromatographic (LC) method was developed for analysis of steam-rolled oat (SRO) baits fortified with either chlorophacinone or diphacinone. Baits were prepared with and without paraffin wax. Chlorophacinone or diphacinone was extracted from wax-free SRO baits with 5 mM tetrabutylammonium phosphate methanolic ion-pairing solution. Wax baits were initially extracted with petroleum ether and then cleaned up by liquid extraction into methanolic ion-pairing solution containing 20% water. SRO extracts were analyzed with reversed-phase ion-pair LC. Chlorophacinone and diphacinone were quantified by UV absorption at 325 nm. Recoveries from SRO fortified with chlorophacinone at 25 and 150 micrograms/g were 90.7 and 90.8%, respectively, whereas for diphacinone at the same levels, recoveries were 93.5 and 92.3%, respectively. Recoveries from wax baits fortified at 25 and 75 micrograms/g chlorophacinone were 98.5 and 100%, respectively, whereas for diphacinone at the same levels, recoveries were 93.6 and 98.0%, respectively. Method limits of detection for chlorophacinone and diphacinone in SRO baits were estimated to be 1.0 and 0.76 micrograms/g, respectively. Method limits of detection for chlorophacinone and diphacinone in wax baits were estimated to be 4.2 and 2.8 micrograms/g, respectively. PMID:9549068

  14. 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.

  15. A reliable and environmentally-friendly liquid-chromatographic method for multi-class determination of fat-soluble UV filters in cosmetic products.

    PubMed

    Chisvert, Alberto; Tarazona, Isuha; Salvador, Amparo

    2013-08-01

    An environmentally-friendly analytical method for the simultaneous determination of 15 fat-soluble ultraviolet (UV) filters currently authorized by the European Union regulation on cosmetic products has been developed. The determination was performed by liquid chromatography with UV spectrophotometric detection. Different parameters, such as type of column, oven temperature, mobile phase composition and flow rate were studied. The best chromatographic separation was obtained under the following conditions: C18 column set at 60°C and gradient ethanol:water (containing 1% formic acid and 20mM of 2-hydroxypropyl-β-cyclodextrin) as mobile phase pumped at 1mL min(-1). 2-Hydroxypropyl-β-cyclodextrin was added as mobile phase modifier to achieve the complete resolution of some of the chromatographic peaks. The 15 target compounds were separated in less than 30min. The method was satisfactorily validated by analyzing three laboratory-made cosmetic samples besides of eleven commercially available cosmetic products containing different combination of the target UV filters. Good accordance of the found levels compared with those of the laboratory-made samples and those of the commercial samples (when available) was achieved. Moreover, excellent recoveries (97-104%) and good intra-day and inter-day precision values at different concentration levels, besides limits of detection values below the μg mL(-1) level, were obtained. These good analytical features, as well as their environmentally-friendly characteristics, make the presented method suitable not only for routine analysis in cosmetics industries, but also as candidate reference method for sunscreen analysis.

  16. 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

  17. 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

  18. 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.

  19. [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

  20. Determination of high-molecular weight polycyclic aromatic hydrocarbons in high performance liquid chromatography fractions of coal tar standard reference material 1597a via solid-phase nanoextraction and laser-excited time-resolved Shpol'skii spectroscopy.

    PubMed

    Wilson, Walter B; Alfarhani, Bassam; Moore, Anthony F T; Bisson, Cristina; Wise, Stephen A; Campiglia, Andres D

    2016-02-01

    This article presents an alternative approach for the analysis of high molecular weight - polycyclic aromatic hydrocarbons (HMW-PAHs) with molecular mass 302 Da in complex environmental samples. This is not a trivial task due to the large number of molecular mass 302 Da isomers with very similar chromatographic elution times and similar, possibly even virtually identical, mass fragmentation patterns. The method presented here is based on 4.2K laser-excited time-resolved Shpol'skii spectroscopy, a high resolution spectroscopic technique with the appropriate selectivity for the unambiguous determination of PAHs with the same molecular mass. The potential of this approach is demonstrated here with the analysis of a coal tar standard reference material (SRM) 1597a. Liquid chromatography fractions were submitted to the spectroscopic analysis of five targeted isomers, namely dibenzo[a,l]pyrene, dibenzo[a,e]pyrene, dibenzo[a,i]pyrene, naphtho[2,3-a]pyrene and dibenzo[a,h]pyrene. Prior to analyte determination, the liquid chromatographic fractions were pre-concentrated with gold nanoparticles. Complete analysis was possible with microliters of chromatographic fractions and organic solvents. The limits of detection varied from 0.05 (dibenzo[a,l]pyrene) to 0.24 µg L(-1) (dibenzo[a,e]pyrene). The excellent analytical figures of merit associated to its non-destructive nature, which provides ample opportunity for further analysis with other instrumental methods, makes this approach an attractive alternative for the determination of PAH isomers in complex environmental samples.

  1. 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...

  2. Pretreatment of lignocellulosic biomass with renewable cholinium ionic liquids: Biomass fractionation, enzymatic digestion and ionic liquid reuse.

    PubMed

    An, Yan-Xia; Zong, Min-Hua; Wu, Hong; Li, Ning

    2015-09-01

    Pretreatment of lignocelluloses is a key step in the biorefinery for production of biofuels and valuable platform chemicals. In this work, various lignocelluloses were pretreated using cholinium ionic liquids (ILs) that are wholly composed of biomaterials, and fractionated into carbohydrate-rich materials (CRMs) and lignin-rich materials (LRMs). Cholinium ILs were found to be effective pretreatment solvents for grass lignocelluloses as well as eucalyptus, resulting in significant improvements in the glucose yields (58-75%) in subsequent enzymatic hydrolysis, while they were inefficient to make pine susceptible to biodegradation. Approximately 46% of lignin in native rice straw was fractionated as LRM after pretreatment using cholinium argininate ([Ch][Arg]). [Ch][Arg] showed excellent recyclability, and the total recovery was as high as 75% after reused for 8 cycles. Besides, rice straw pretreated by the recycled IL remained highly digestible, and good glucose yields (63-75%) were achieved after its enzymatic hydrolysis.

  3. Pretreatment of lignocellulosic biomass with renewable cholinium ionic liquids: Biomass fractionation, enzymatic digestion and ionic liquid reuse.

    PubMed

    An, Yan-Xia; Zong, Min-Hua; Wu, Hong; Li, Ning

    2015-09-01

    Pretreatment of lignocelluloses is a key step in the biorefinery for production of biofuels and valuable platform chemicals. In this work, various lignocelluloses were pretreated using cholinium ionic liquids (ILs) that are wholly composed of biomaterials, and fractionated into carbohydrate-rich materials (CRMs) and lignin-rich materials (LRMs). Cholinium ILs were found to be effective pretreatment solvents for grass lignocelluloses as well as eucalyptus, resulting in significant improvements in the glucose yields (58-75%) in subsequent enzymatic hydrolysis, while they were inefficient to make pine susceptible to biodegradation. Approximately 46% of lignin in native rice straw was fractionated as LRM after pretreatment using cholinium argininate ([Ch][Arg]). [Ch][Arg] showed excellent recyclability, and the total recovery was as high as 75% after reused for 8 cycles. Besides, rice straw pretreated by the recycled IL remained highly digestible, and good glucose yields (63-75%) were achieved after its enzymatic hydrolysis. PMID:26026293

  4. 1.1 μm superficially porous particles for liquid chromatography: part II: column packing and chromatographic performance.

    PubMed

    Blue, Laura E; Jorgenson, James W

    2015-02-01

    The predicted advantages of superficially porous particles over totally porous particles are decreased eddy dispersion, longitudinal diffusion, and resistance to mass transfer contributions to the theoretical plate height. While sub-2 micron superficially porous particles are commercially available, further improvements in performance are predicted by decreasing the particle diameter and decreasing the porous layer thickness. 1.1 μm superficially porous particles with 187Å pores have been synthesized using a layer-by-layer method tuned for production of smaller diameter particles. Following synthesis, these particles were packed into 30 μm i.d. capillary columns and their chromatographic performance evaluated using electrochemical detection. Based on the initial studies, the column efficiency did not meet theory, but was similar to the commercially available products tested. It is believed that the column packing process plays a critical role in the sub-par column performance. To determine if column efficiency could be predicted by solvent-particle interactions, in-solution optical microscopy and sedimentation velocity of particles in various slurry solvents were investigated and compared to column performance. Aggregating slurry solvents, such as methanol were found to produce columns with increased efficiency. The hmin for a column packed with an acetone slurry and a methanol slurry at 3mg/mL were found to be 6.3 and 3.5, respectively. Increasing the slurry concentration to 25mg/mL further improved the efficiency, producing a column with an hmin of 2.6. These efficiency results were accurately predicted by in-solution optical microscopy.

  5. Fractionation of sugarcane bagasse using a combined process of dilute acid and ionic liquid treatments.

    PubMed

    Diedericks, Danie; van Rensburg, Eugéne; Görgens, Johann F

    2012-08-01

    Biorefineries processing lignocellulose will produce chemicals and fuels from chemical constituents, cellulose, hemicelluloses, and lignin to replace fossil-derived products. Fractionation of sugarcane bagasse into three pure streams of chemical constituents was addressed through dissolution of constituents with the ionic liquids, 1-ethyl-3-methylimidazolium acetate ([EMiM]CH(3)COO) or 1-butyl-3-methylimidazolium methyl sulfate ([BMiM]MeSO(4)). Constituents were isolated from the reaction mixture with the anti-solvents acetone (Ā), acetone-water (AW), and sodium hydroxide (NaOH). Delignification was enhanced by NaOH, although resulting in impure product streams. Xylose pre-extraction (75 % w/w) by dilute acid pretreatment, prior to ionic liquid treatment, improved lignin purity after anti-solvent separation. Fractionation efficiency of the combined process was maximized (84 %) by ionic liquid treatment at 125 °C for 120 min, resulting in 80.2 % (w/w) lignin removal and 76.5 % (w/w) lignin recovery. Ionic liquids achieved similar degrees of delignification, although fully digestible cellulose-rich solids were produced only by [EMiM]CH(3)COO treatment.

  6. 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

  7. Reversed-phase high-performance liquid chromatographic determination of enoxacin and 4-oxo-enoxacin in human plasma and prostatic tissue. Application to a pharmacokinetic study.

    PubMed

    Hamel, B; Audran, M; Costa, P; Bressolle, F

    1998-07-01

    A simple high-performance liquid chromatographic method has been developed for the simultaneous determination of enoxacin and 4-oxo-enoxacin in plasma and prostatic tissue. The work-up procedure involves a liquid-liquid extraction step followed by isocratic chromatography on a reversed-phase analytical column, with ultraviolet absorbance detection (lambda = 340 nm). Using a mobile phase of 20.9% (v/v) acetonitrile buffer (pH 2.1), adequate retention time and separation among the analytes has been obtained using tetrabutylammonium hydroxide included in the eluent. Retention times are 5.2 min for enoxacin, 6.8 min for pefloxacin and 12 min for 4-oxo-enoxacin. For plasma and prostatic tissue, the precision of the assay was below 9%. The percent recovery from the nominal values for accuracy ranged from 94 to 108%. The limits of quantitation were 20 ng/ml for plasma and 50 ng/g for tissue (precision < 18%). The detection limits were 10 ng/ml and 25 ng/g, respectively. The calibration curves were linear from 20 to 1000 ng/ml for plasma and from 50 to 2500 ng/g for tissue. In plasma, the extraction recoveries averaged 52% for enoxacin and 63% for 4-oxo-enoxacin. In prostatic tissue, they were 57 and 76% for the two analytes, respectively. This method has been employed for the determination of enoxacin and 4-oxo-enoxacin in plasma and prostatic tissue samples from patients following repeated oral administration of enoxacin (400 mg twice a day for four days).

  8. Comparison of gravimetric and gas chromatographic methods for assessing performance of textile materials against liquid pesticide penetration.

    PubMed

    Shaw, Anugrah; Abbi, Ruchika

    2004-01-01

    Penetration of liquid pesticides through textile materials is a criterion for determining the performance of protective clothing used by pesticide handlers. The pipette method is frequently used to apply liquid pesticides onto textile materials to measure penetration. Typically, analytical techniques such as Gas Chromatography (GC) are used to measure percentage penetration. These techniques are labor intensive and costly. A simpler gravimetric method was developed, and tests were conducted to compare the gravimetric and GC methods of analysis. Three types of pesticide formulations and 4 fabrics were used for the study. Diluted pesticide formulations were pipetted onto the test specimens and percentage penetration was measured using the 2 methods. For homogeneous formulation, the results of the two methods were fairly comparable. However, due to the filtering action of the textile materials, there were differences in the percentage penetration between the 2 methods for formulations that were not homogeneous.

  9. 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.

  10. 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.

  11. Indole-3-acetic Acid Levels of Plant Tissue as Determined by a New High Performance Liquid Chromatographic Method 1

    PubMed Central

    Sweetser, Philip B.; Swartzfager, Dennis G.

    1978-01-01

    A method for the analysis of indole-3-acetic acid (IAA) in plant extracts has been developed based on high performance liquid chromatography separation of IAA on a microparticulate strong anion exchange column followed by quantitation with two selective detectors: an electrochemical, carbon paste amperometric detector and/or a fluorescence detector. The detection limit for IAA is less than 1 nanogram with the fluorescence detector and less than 50 picograms with the electrochemical detector. The IAA levels are reported for various tissues of wheat, pinto beans, soybeans, cotton, and corn. PMID:16660271

  12. A SURVEY OF LIQUID CHROMATOGRAPHIC-MASS SPECTROMETRIC ANALYSIS OF MERCAPTURIC ACID BIOMARKERS IN OCCUPATIONAL AND ENVIRONMENTAL EXPOSURE MONITORING

    PubMed Central

    Mathias, Patricia I.; B’Hymer, Clayton

    2015-01-01

    High-performance liquid chromatography/mass spectrometry (HPLC/MS) is sensitive and specific for targeted quantitative analysis and is readily utilized for small molecules from biological matricies. This brief review describes recent selected HPLC/MS methods for the determination of urinary mercapturic acids (mercapturates) which are useful as biomarkers in characterizing human exposure to electrophilic industrial chemicals in occupational and environmental studies. Electrophilic compounds owing to their reactivity are used in chemical and industrial processes. They are present in industrial emissions, are combustion products of fossil fuels, and are components in tobacco smoke. Their presence in both the industrial and general environment are of concern for human and environmental health. Urinary mercapturates which are the products of metabolic detoxification of reactive chemicals provide a non-invasive tool to investigate human exposure to electrophilic toxicants. Selected recent mercapturate quantification methods are summarized and specific cases are presented. The biological formation of mercapturates is introduced and their use as biomarkers of metabolic processing of electrophilic compounds is discussed. Also, the use of liquid chromatography/tandem mass spectrometry in simultaneous determinations of the mercapturates of multiple parent compounds in a single determination is considered, as well as future trends and limitations in this area of research. PMID:24746702

  13. Two-step microextraction combined with high performance liquid chromatographic analysis of pyrethroids in water and vegetable samples.

    PubMed

    Mukdasai, Siriboon; Thomas, Chunpen; Srijaranai, Supalax

    2014-03-01

    Dispersive liquid microextraction (DLME) combined with dispersive µ-solid phase extraction (D-µ-SPE) has been developed as a new approach for the extraction of four pyrethroids (tetramethrin, fenpropathrin, deltamethrin and permethrin) prior to the analysis by high performance liquid chromatography (HPLC) with UV detection. 1-Octanol was used as the extraction solvent in DLME. Magnetic nanoparticles (Fe3O4) functionalized with 3-aminopropyl triethoxysilane (APTS) were used as the dispersive in DLME and as the adsorbent in D-µ-SPE. The extracted pyrethroids were separated within 30 min using isocratic elution with acetonitrile:water (72:28). The factors affecting the extraction efficiency were investigated. Under the optimum conditions, the enrichment factors were in the range of 51-108. Linearity was obtained in the range 0.5-400 ng mL(-1) (tetramethrin) and 5-400 ng mL(-1) (fenpropathrin, deltamethrin and permethrin) with the correlation coefficients (R(2)) greater than 0.995. Detection limits were 0.05-2 ng mL(-1) (water samples) and 0.02-2.0 ng g(-1) (vegetable samples). The relative standard deviations of peak area varied from 1.8 to 2.5% (n=10). The extraction recoveries of the four pyrethroids in field water and vegetable samples were 91.7-104.5%. The proposed method has high potential for use as a sensitive method for determination of pyrethroid residues in water and vegetable samples.

  14. Microemulsion liquid chromatographic method for simultaneous separation and determination of six flavonoids of Apocynum venetum leaf extract.

    PubMed

    Song, Rui juan; Zhou, Jun

    2015-07-15

    A simple, cost-effective, and efficient method was developed for the rapid simultaneous separation and determination of six flavonoids (rutin, hyperoside, quercetin-3-O-sophoroside, isoquercitrin, astragalin and quercetin) of Apocynum venetum leaf extract by reversed phase high performance liquid chromatography using a microemulsion system mixture as the mobile phase. Separations were performed on the Zorbax Extend-C18 column with UV detection at 360nm. The flow rate was 0.8mLmin(-1). The optimized microemulsion mobile phase consisted of 2.5% (v/v) n-butanol, 1.2% (v/v) of Genapol X-080, 0.5% (v/v) ethyl acetate and 95.8% (w/v) of aqueous 20mM phosphoric acid, pH adjusted to 6.0 with 0.3% triethylamine. Under the optimized conditions, the calibration curve for six flavonoids was linear in the range of 5-1000μgmL(-1) with the correlation coefficients greater than 0.9994. The intra-day and inter-day precision (RSD) were below 8.11% and the limits of detection (LOD) for the six flavonoids were 1.7-6.0μgmL(-1) (S/N=3). The microemulsion liquid chromatography (MELC) method was successfully applied to separate and determine the six flavonoids of A. venetum leaf extract.

  15. A survey of liquid chromatographic-mass spectrometric analysis of mercapturic acid biomarkers in occupational and environmental exposure monitoring.

    PubMed

    Mathias, Patricia I; B'Hymer, Clayton

    2014-08-01

    High-performance liquid chromatography/mass spectrometry (HPLC/MS) is sensitive and specific for targeted quantitative analysis and is readily utilized for small molecules from biological matrices. This brief review describes recent selected HPLC/MS methods for the determination of urinary mercapturic acids (mercapturates) which are useful as biomarkers in characterizing human exposure to electrophilic industrial chemicals in occupational and environmental studies. Electrophilic compounds owing to their reactivity are used in chemical and industrial processes. They are present in industrial emissions, are combustion products of fossil fuels, and are components in tobacco smoke. Their presence in both the industrial and general environments are of concern for human and environmental health. Urinary mercapturates which are the products of metabolic detoxification of reactive chemicals provide a non-invasive tool to investigate human exposure to electrophilic toxicants. Selected recent mercapturate quantification methods are summarized and specific cases are presented. The biological formation of mercapturates is introduced and their use as biomarkers of metabolic processing of electrophilic compounds is discussed. Also, the use of liquid chromatography/tandem mass spectrometry in simultaneous determinations of the mercapturates of multiple parent compounds in a single determination is considered, as well as future trends and limitations in this area of research.

  16. 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.

  17. 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

  18. 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.

  19. 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%.

  20. 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)

  1. 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.

  2. 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

  3. 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).

  4. Development and validation of a stability-indicating micellar liquid chromatographic method for the determination of timolol maleate in the presence of its degradation products.

    PubMed

    Rizk, Mohamed S; Merey, Hanan A; Tawakkol, Shereen M; Sweilam, Mona N

    2015-04-01

    A stability-indicating micellar liquid chromatographic (MLC) method was developed and validated for the quantitative determination of timolol maleate (TM) in the presence of its degradation products resulting from accelerated degradation in a run time not more than 8 min. TM was subjected to stress conditions of hydrolysis (including alkaline, acidic and thermal hydrolysis) and oxidation. An isocratic, rapid and mobile phase saving the micellar LC method was developed with a BioBasic phenyl column (150 × 1.0 mm, 5 µm particle size) and a micellar mobile phase composed of 0.1 M sodium dodecyl sulfate, 10% of 1-propanol and 0.1% of triethylamine in 0.035 M ortho-phosphoric acid. The flow rate of the mobile phase was 0.1 mL/min. UV detection was adjusted at 298 nm and performed at room temperature. The method has been validated according to the International Conference on Harmonisation guidelines. The method is successfully applied for the determination of TM in bulk powder and pharmaceutical dosage form.

  5. Incorporating high-pressure electroosmotic pump and a nano-flow gradient generator into a miniaturized liquid chromatographic system for peptide analysis.

    PubMed

    Chen, Apeng; Lynch, Kyle B; Wang, Xiaochun; Lu, Joann J; Gu, Congying; Liu, Shaorong

    2014-09-24

    We integrate a high-pressure electroosmotic pump (EOP), a nanoflow gradient generator, and a capillary column into a miniaturized liquid chromatographic system that can be directly coupled with a mass spectrometer for proteomic analysis. We have recently developed a low-cost high-pressure EOP capable of generating pressure of tens of thousands psi, ideal for uses in miniaturized HPLC. The pump worked smoothly when it was used for isocratic elutions. When it was used for gradient elutions, generating reproducible gradient profiles was challenging; because the pump rate fluctuated when the pump was used to pump high-content organic solvents. This presents an issue for separating proteins/peptides since high-content organic solvents are often utilized. In this work, we solve this problem by incorporating our high-pressure EOP with a nano-flow gradient generator so that the EOP needs only to pump an aqueous solution. With this combination, we develop a capillary-based nano-HPLC system capable of performing nano-flow gradient elution; the pump rate is stable, and the gradient profiles are reproducible and can be conveniently tuned. To demonstrate its utility, we couple it with either a UV absorbance detector or a mass spectrometer for peptide separations.

  6. 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

  7. 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.

  8. 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.

  9. Chaotropic salts in liquid chromatographic method development for the determination of pramipexole and its impurities following quality-by-design principles.

    PubMed

    Vemić, Ana; Rakić, Tijana; Malenović, Anđelija; Medenica, Mirjana

    2015-01-01

    The aim of this paper is to present a development of liquid chromatographic method when chaotropic salts are used as mobile phase additives following the QbD principles. The effect of critical process parameters (column chemistry, salt nature and concentration, acetonitrile content and column temperature) on the critical quality attributes (retention of the first and last eluting peak and separation of the critical peak pairs) was studied applying the design of experiments-design space methodology (DoE-DS). D-optimal design is chosen in order to simultaneously examine both categorical and numerical factors in minimal number of experiments. Two ways for the achievement of quality assurance were performed and compared. Namely, the uncertainty originating from the models was assessed by Monte Carlo simulations propagating the error equal to the variance of the model residuals and propagating the error originating from the model coefficients' calculation. The baseline separation of pramipexole and its five impurities is achieved fulfilling all the required criteria while the method validation proved its reliability.

  10. 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

  11. 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

  12. 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

  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. 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

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. Development and validation of a high-performance liquid chromatographic method for the determination of clomazone residues in surface water.

    PubMed

    Zanella, R; Primel, E G; Gonçalves, F F; Martins, A F

    2000-12-29

    A method is described for the determination of clomazone residues in surface water by high-performance liquid chromatography with UV detection. The method involves solid-phase extraction with C18 extraction tubes. Clomazone was separated on a C18 column with a mobile phase of methanol-water (65:35, v/v) at pH 4.0 and a flow-rate of 1.0 ml/min. After optimization of the extraction and separation conditions, the method was validated. The method developed can be used for determination of clomazone in surface water, at the limit of 0.1 mcirog/l set by the European Union drinking water directive, with a 400-fold preconcentration.

  1. Characterization of organotin species using microbore and capillary liquid chromatographic techniques with an epifluorescence microscope as a novel imaging detector.

    PubMed

    Blair, W R; Parks, E J; Olson, G J; Brinckman, F E; Valeiras-Price, M C; Bellama, J M

    1987-12-11

    The novel application of a UV epifluorescence microscope as an imaging detector for microbore and capillary high-performance liquid chromatography (HPLC) is reported. The microscope is focused on an in-line quartz flow cell incorporated down stream of a microbore HPLC column or directly on an optically clear portion of fused-silica capillary columns for analyte detection. The effect of different fluorescent ligand to analyte ratios on detection limits is also reported, as well as the effect of different image volume sizes produced by changes in microscope objective lens magnification power. Determination of relative sensitivities an detection limits for methyl- and butyltin compounds, complexed with fluorescent dyes, reveals that the organotins show decreasing sensitivity as the number of alkyl substituents on the tin atom increases, with minimum detectable amounts of 6-160 pg of analyte-ligand complex.

  2. High performance liquid chromatographic separations of gas oil samples and their hydrotreated products using commercial normal phases.

    PubMed

    Oro, Nicole E; Lucy, Charles A

    2011-10-28

    Three commercially available high performance liquid chromatography columns are used in normal phase or quasi-normal phase mode for the separation of gas oil samples. The columns are tested with 20 analytical standards to determine their suitability for separations of petroleum samples and their ability to separate the nitrogen group-types (pyrrole and pyridine) found in petroleum. The columns studied are polymeric hypercrosslinked polystyrene (HGN), a biphenyl phase, and a Chromegabond "DNAP" column from ES Industries. The HGN column separates gas oils based on both ring structure and heteroatom, while the biphenyl phase has low retention of most compounds studied in quasi-normal phase mode. The "DNAP" column is selective for nitrogen-containing compounds, separating them from PAHs as well as oxygen and sulphur compounds. Retention data of standards on all three columns is shown, along with chromatograms of gas oil samples on the HGN and "DNAP" columns.

  3. 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

  4. 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

  5. Automated direct high-performance liquid chromatographic assay for estetrol, estriol, cortisone and cortisol in serum and amniotic fluid.

    PubMed

    Noma, J; Hayashi, N; Sekiba, K

    1991-07-17

    An automated direct assay for the simultaneous determination of unconjugated estetrol, estriol, cortisone and cortisol in serum and amniotic fluid, using high-performance liquid chromatography with electrochemical detection and ultraviolet detection, has been developed. The analysis time is ca. 1 h. This system offers good reproducibility with low coefficients of variation (estetrol, 2.3%; estriol, 2.3%; cortisone, 2.6%; cortisol, 1.9%). Detection limits are low enough for routine determinations (estetrol and estriol, 150 pg; cortisone and cortisol, 5 ng). Comparison of the values measured by the present method and by radioimmunoassay revealed significant correlations for estetrol (r = 0.787, p less than 0.01), estriol (r = 0.957, p less than 0.01), cortisone (r = 0.956, p less than 0.01) and cortisol (r = 0.865, p less than 0.01). This system proved to be valuable in monitoring feto-placental function. PMID:1770108

  6. Biocompatible chiral monolithic stationary phase synthesized via atom transfer radical polymerization for high performance liquid chromatographic analysis.

    PubMed

    Wang, Huai-Song; Feng, Xia-Yi; Wei, Ji-Ping

    2015-08-28

    Novel biocompatible chiral monolithic stationary phase was prepared by reverse and direct atom transfer radical polymerization (ATRP) methods. By taking advantages of the controlled/living property of ATRP method, the chiral monolith was prepared by reverse ATRP (RATRP) firstly. An attractive feature of RATRP is the prepared polymer containing a terminal radically transferable atom that can initiate another post-polymerization reaction by direct ATRP. Then, the biocompatible poly(hydroxyethyl methacrylate) (PHEMA) was grafted on the surface of the chiral monolith by direct ATRP as a diffusion barrier for proteins. This biocompatible chiral monolith was successfully used as restricted access stationary phase for determination of enantiomers in biological samples with direct injection by high-performance liquid chromatography (HPLC). PMID:26199103

  7. 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

  8. Liquid phase microextraction using knitting wool as the extractant phase holder before chromatographic analysis: a new approach for trace analysis.

    PubMed

    Zhang, Yufeng; Lee, Hian Kee

    2013-01-18

    In this paper, a novel liquid phase microextraction (LPME) approach was developed in which a piece of knitting wool was used as the extractant solvent holder. Owing to the absorbability of the wool, the extractant could be easily held within the material. When the wool containing the organic solvent was exposed to the sample solution, analytes could directly diffuse from the sample solution to the solvent. Ultraviolet (UV) filters ([2,4-dihydroxybenzophenone (BP-1), benzophenone (BP) and 2-hydroxy-4-methoxybenzophenone (BP-3)]) were used as model analytes to evaluate the procedure. Parameters that affect the extraction efficiency (selection of organic solvent, volume of the extractant, agitation speed, extraction time, salt concentration and pH) were investigated. The proposed method in combination with liquid chromatography-UV detection, provided good enrichment factors up to 366, with relative standard deviations of between 0.6% and 4.2% on the same piece of wool, and good linearity from 0.1 ng/ml to 100 ng/ml for all the analytes with regression coefficients of between 0.9998 and 0.9999. The limits of quantification of these compounds, calculated at S/N=10, were 0.1 ng/ml, 0.07 ng/ml and 0.1 ng/ml for BP-1, BP, BP-3, respectively. The method was applied to the determination of BP-type UV filters in swimming pool water. This is the first report of an application of knitting wool as a solvent holder for LPME. The procedure is cost-effective, and easy to operate. PMID:23276647

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. [Surface-active agents from the group of polyoxyethylated glycerol esters of fatty acids. Part II. Chromatographic analysis and basic viscosity parameters as a estimate criterion of efficiency of catalytic oxyethylation of Lard's fractions (Adeps suillus FP VII)].

    PubMed

    Piotrowska, Jowita Barbara; Nachajski, Michał Jakub; Lukosek, Marek; Kosno, Jacek; Zgoda, Marian Mikołaj

    2011-01-01

    The catalytic oxyethylation products of Lard's fractions and Tweens--as a reference products, were analised by chromatographic analysis HPLC and GPC. The above part was determination average molecular weights dispersion (Mw I Mn) and the content of polyethylene glycols (PEG), which are obtained during catalytic oxyethylation, and determination iodine value of the product (L(J2)). Viscosity measurements were carried out by Ubelohde method and enabled determination of basic viscosity and hydrodynamic parameters. The obtained results indicate that, comparing reference products--polysorbates, Tweens, products of triglycerides oxyethylation contain significantly less, in some cases very small amount of polyethylene glycols (PEG), and also maintained a high amount of unsaturated fatty acids (oleic acid), which is proven by the iodine value. Numerical value n(s) /H2O/ confirms important disparity of micells palisad structure, which are created based on oxyethylated triglycerides nTE = 40. That indicates significant solubilization possibilities of their aqueous solutions Cexp < or = Cmc.

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. 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

  2. High-performance liquid chromatographic determination of azaarenes and their metabolites in groundwater affected by creosote wood preservatives.

    PubMed

    Ondrus, M G; Steinheimer, T R

    1990-06-01

    Polynuclear azaheterocyclic compounds (azaarenes) are nitrogen-containing analogs of polycyclic aromatic hydrocarbons (PAHs). The nitrogen atom in the ring system causes these compounds to be slightly polar and considerably more water soluble than related PAHs. A method using a solid-surface sorption technique to extract and concentrate azaarenes and their principle metabolites present in groundwater that contains creosote waste is described. Analyte isolation and concentration is accomplished by solid-phase extraction on n-octadecyl cartridges followed by instrumental determination involving high-performance liquid chromatography. Separations and detection are achieved using flexible-walled, wide-bore columns with ultraviolet and fluorescence photometric detectors connected in series. Fluorescence detection alone is insufficient because the fluorescence response produced by two-ring azaarenes is limited. Short wavelength (229 nm) absorbance detection provides improved sensitivity for these compounds and peak rationing for more definitive identification. In this study, oxygen-containing metabolites of quinoline, isoquinoline, and acridine are detected in groundwater from hazardous waste sites in Pensacola, Florida and St. Louis Park, Minnesota. Concentrations ranging from mg/L to ng/L are measured. The dependence of measured octanol-water partition coefficients on pH is discussed in the context of the isolation chemistry. As a direct bacterial degradation product of acridine with a relatively long environmental persistence, 9-acridinone may serve as a biogenic marker signaling creosote contamination of groundwater.

  3. 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

  4. 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

  5. Determination of descriptors for polycyclic aromatic hydrocarbons and related compounds by chromatographic methods and liquid-liquid partition in totally organic biphasic systems.

    PubMed

    Ariyasena, Thiloka C; Poole, Colin F

    2014-09-26

    Retention factors on several columns and at various temperatures using gas chromatography and from reversed-phase liquid chromatography on a SunFire C18 column with various mobile phase compositions containing acetonitrile, methanol and tetrahydrofuran as strength adjusting solvents are combined with liquid-liquid partition coefficients in totally organic biphasic systems to calculate descriptors for 23 polycyclic aromatic hydrocarbons and eighteen related compounds of environmental interest. The use of a consistent protocol for the above measurements provides descriptors that are more self consistent for the estimation of physicochemical properties (octanol-water, air-octanol, air-water, aqueous solubility, and subcooled liquid vapor pressure). The descriptor in this report tend to have smaller values for the L and E descriptors and random differences in the B and S descriptors compared with literature sources. A simple atom fragment constant model is proposed for the estimation of descriptors from structure for polycyclic aromatic hydrocarbons. The new descriptors show no bias in the prediction of the air-water partition coefficient for polycyclic aromatic hydrocarbons unlike the literature values.

  6. 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

  7. 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.

  8. Comparison of chromatographic band profiles obtained under microwave irradiated and non-irradiated reversed-phase liquid chromatography column.

    PubMed

    Galinada, Wilmer A; Guiochon, Georges

    2005-10-28

    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 degrees C, respectively.

  9. The effect of sulfur on vapor liquid fractionation of metals in hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Pokrovski, Gleb S.; Borisova, Anastassia Yu.; Harrichoury, Jean-Claude

    2008-02-01

    Despite the growing evidence that the vapor phase, formed through magma degassing and ore fluid boiling, can selectively concentrate and transport metals, the effects of major volatile components like sulfur, chlorine or carbon dioxide on the metal vapor-liquid fractionation and vapor-phase transport under magmatic-hydrothermal conditions remain poorly known. We performed systematic experiments to investigate the effect of sulfur ligands on metal vapor-liquid partitioning in model H 2O-S-NaCl-KCl-NaOH systems at temperatures from 350 to 500 °C. Results show that at acidic-to-neutral conditions, vapor-liquid equilibrium distribution coefficients, Km = mvapor / mliquid, where m is the mass concentration of the metal in corresponding phase, of metalloids (As, Sb) and base metals (Zn, Fe, Pb, Ag) are in the range 0.1-1.0 and 0.001-0.1, respectively, and are not significantly affected by the presence of geologically common sulfur concentrations, up to 1-3 wt.% S. In contrast, the partitioning of Cu, Au, and Pt into the vapor increases by a factor of 100 in comparison to the S-free water-salt system, yielding Km values of 0.5-1.0, 1-10, and 10-20, respectively, due to formation of volatile neutral complexes with H 2S and, possibly, SO 2. In neutral-to-basic systems, Zn, Pb, Fe and Ag show 10-100-fold increase of their partition coefficients, whereas Cu, Au and Pt exhibit Km values of up to several orders of magnitude lower, compared to acidic conditions at similar temperature, pressure and sulfur contents. These vapor-liquid distribution patterns result from combined effects of i) formation of volatile species with reduced sulfur ligands in the vapor phase, ii) changes in the metal speciation in the coexisting liquid phase as a function of pH, and iii) solute-solvent interactions in both phases. Our data explain the vapor-liquid fractionation trends for many metals as inferred in coexisting brine and vapor inclusions from magmatic-hydrothermal deposits, and provide a

  10. Experimental determination of the Mo isotope fractionation factor between metal and silicate liquids

    NASA Astrophysics Data System (ADS)

    Hin, R. C.; Burkhardt, C.; Schmidt, M. W.; Bourdon, B.

    2011-12-01

    The conditions and chemical consequences of core formation have mainly been reconstructed from experimentally determined element partition coefficients between metal and silicate liquids. However, first order questions such as the mode of core formation or the nature of the light element(s) in the Earth's core are still debated [1]. In addition, the geocentric design of most experimental studies leaves the conditions of core formation on other terrestrial planets and asteroids even more uncertain than for Earth. Through mass spectrometry, records of mass-dependent stable isotope fractionation during high-temperature processes such as metal-silicate segregation are detectable. Stable isotope fractionation may thus yield additional constrains on core formation conditions and its consequences for the chemical evolution of planetary objects. Experimental investigations of equilibrium mass-dependent stable isotope fractionation have shown that Si isotopes fractionate between metal and silicate liquids at temperatures of 1800°C and pressures of 1 GPa, while Fe isotopes leave no resolvable traces of core formation processes [2,3]. Molybdenum is a refractory and siderophile trace element in the Earth, and thus much less prone to complications arising from mass balancing core and mantle and from potential volatile behaviour than other elements. To determine equilibrium mass-dependent Mo isotope fractionation during metal-silicate segregation, we have designed piston cylinder experiments with a basaltic silicate composition and an iron based metal with ~8 wt% Mo, using both graphite and MgO capsules. Metal and silicate phases are completely segregated by the use of a centrifuging piston cylinder at ETH Zurich, thus preventing analysis of mixed metal and silicate signatures. Molybdenum isotope compositions were measured using a Nu Instruments 1700 MC-ICP-MS at ETH Zurich. To ensure an accurate correction of analytical mass fractionation a 100Mo-97Mo double spike was admixed

  11. 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.

  12. Determining orthogonal and similar chromatographic systems from the injection of mixtures in liquid chromatography-diode array detection and the interpretation of correlation coefficients color maps.

    PubMed

    Van Gyseghem, E; Crosiers, I; Gourvénec, S; Massart, D L; Vander Heyden, Y

    2004-02-13

    Generic orthogonal chromatographic systems might be helpful tools as potential starting points in the development of methods to separate impurities and the active substance in drugs with unknown impurity profiles. The orthogonality of 38 chromatographic systems was evaluated from weighted-average-linkage dendrograms and color maps, both based on the correlation coefficients between the retention factors on the different systems. On each chromatographic system, 68 drug substances were injected as mixtures of three or four components to increase the throughput. The (overlapping) peaks were identified and resolved with a peak purity algorithm, orthogonal projection approach (OPA). The visualization techniques applied allowed a simple evaluation of orthogonal and (groups of) similar systems.

  13. Extraction of carbamate pesticides in fruit samples by graphene reinforced hollow fibre liquid microextraction followed by high performance liquid chromatographic detection.

    PubMed

    Ma, Xiaoxing; Wang, Juntao; Wu, Qiuhua; Wang, Chun; Wang, Zhi

    2014-08-15

    Graphene reinforced hollow fibre liquid phase microextraction combined with high performance liquid chromatography-diode array detection was developed for the determination of some carbamate pesticides (metolcarb, carbaryl, isoprocarb, and diethofencarb) in fruit samples. The main parameters that affect the extraction efficiency for the carbamates were investigated. Under the optimum conditions, a good linearity was observed in the range of 1.0-100.0 ng g(-1) for carbaryl and 3.0-100.0 ng g(-1) for the other three analytes, with the correlation coefficients (r) of 0.9965-0.9993. The limits of detection of the method ranged from 0.2 to 1.0 ng g(-1). The relative standard deviations were in the range from 6.2% to 7.8%. The results indicated that the developed method is sensitive and efficient for the determination of the carbamate pesticides in fruit samples.

  14. 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

  15. 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

  16. 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.

  17. Application of a liquid chromatographic/tandem mass spectrometric method to a urinary excretion study of rabeprazole and two of its metabolites in healthy human urine.

    PubMed

    Lu, Chengtao; Jia, Yanyan; Song, Ying; Li, Xueqing; Sun, Yuan; Zhao, Jinyi; Wang, Shan; Shi, Lei; Wen, Aidong; Ding, Li

    2015-04-15

    To study urinary excretion properties of rabeprazole and two of its metabolites, i.e. rabeprazole thioether and desmethyl rabeprazole thioether in human urine, a sensitive, selective, accurate and precise method for the quantification of rabeprazole and two of its metabolites using a liquid chromatographic/tandem mass spectrometric method has been developed and validated. Starting with a 200 μL urine aliquot, a general sample preparation was performed using protein precipitation with methanol. Analytes were separated on a Dikma Inspire™ C18 column (150 mm × 2.1mm, 5 μm) using a mixture of methanol and aqueous 10mM ammonium acetate buffer containing 0.05% formic acid (55:45, v/v) as mobile phase. Linearity was obtained over the concentration range of 0.1446-96.38 ng/mL, 0.3198-319.8 ng/mL and 0.05160-82.53 ng/mL for rabeprazole, rabeprazole thioether, desmethyl rabeprazole thioether in human urine, respectively. The fully validated method was applied to a urine excretion study of rabeprazole sodium administered as a 30 min intravenous infusion for the first time. The calculated cumulative urinary recovery just reached 0.04745‰, 1.272‰ and 0.1631‰ of dose within 24h post-dose for rabeprazole, rabeprazole thioether, and desmethyl rabeprazole thioether, respectively, after intravenous infusion administration, indicating that rabeprazole and its two main metabolites undergo substantial non-renal elimination in healthy Chinese volunteers. PMID:25755073

  18. [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.

  19. A multiresidue liquid chromatographic/tandem mass spectrometric method for the detection and quantitation of 15 nonsteroidal anti-inflammatory drugs (NSAIDs) in bovine meat and milk.

    PubMed

    van Pamel, Els; Daeseleire, Els

    2015-06-01

    This study concerns a validated liquid chromatographic/tandem mass spectrometric (LC-MS/MS) multiresidue method for the simultaneous detection, identification, and quantitation of 15 nonsteroidal anti-inflammatory drugs (NSAIDs) in bovine meat and milk. The NSAIDs considered are carprofen, diclofenac, flufenamic acid, flunixin (5-hydroxyflunixin as marker metabolite in milk), ketoprofen, mefenamic acid, meloxicam, 4-methylaminoantipyrine (marker metabolite of metamizole in meat and milk), naproxen, niflumic acid, phenylbutazone (and metabolite oxyphenbutazone), ramifenazone, salicylic acid, and tolfenamic acid. These compounds were chosen as representatives of different chemical subclasses of NSAIDs. Flunixin-d3, diclofenac-d4, 4-aminoantipyrine-d3, and phenylbutazone-d10 were used as internal standards. Performance characteristics were validated according to the Commission Decision 2002/657/EC (Off J Eur Communities, L221: 8-36). Recovery percentages varied between 81 and 114% for bovine meat and between 79 and 118% for milk. Repeatability percentages were within the range of 1-12% for meat and between 1 and 17% for milk, whereas the intralaboratory reproducibility varied between 3 and 19% for meat and between 3 and 23% for milk. The decision limit and the detection capability for bovine meat were within the range of 0.5-579 μg kg(-1)and 0.6-642 μg kg(-1), respectively. Those for milk were within the range of 0.12-55 μg kg(-1) and 0.14-61 μg kg(-1), respectively. The methods developed were successfully applied for proficiency test samples and routine samples analyzed in the laboratory. The methodology concerns fast, user-friendly, and sensitive methods, which can be easily extended for other compounds and matrices. In general, such multiresidue methods contribute to the reduction of human exposure to these veterinary drug residues by consumption of contaminated bovine-derived products such as meat and milk.

  20. 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

  1. Stability-indicating reversed-phase liquid chromatographic method for simultaneous determination of atorvastatin and ezetimibe from their combination drug products.

    PubMed

    Chaudhari, Bharat G; Patel, Natvarlal M; Shah, Paresh B; Patel, Laxman J; Patel, Vipul P

    2007-01-01

    A simple, precise, and rapid stability-indicating reversed-phase column liquid chromatographic (RP-LC) method has been developed and subsequently validated for simultaneous estimation of atorvastatin (ATV) and ezetimibe (EZE) from their combination drug product. The proposed RP-LC method utilizes a LiChrospher 100 C18, 5 microm, 250 x 4.0 mm id column at ambient temperature; the optimum mobile phase consists of acetonitrile-water-methanol (45 + 40 + 15, v/v/v) with apparent pH adjusted to 4.0 +/- 0.1; mobile phase flow rate of 1.0 mL/min; and UV detection at 250 nm. ATV, EZE, and their combination drug product were exposed to thermal, photolytic, hydrolytic, and oxidative stress conditions, and the stressed samples were analyzed by the proposed method. There were no other coeluting, interfering peaks from excipients, impurities, or degradation products due to variable stress conditions, and the method is specific for the estimation of ATV and EZE in the presence of degradation products. The response was linear over the concentration range of 1-80 microg/mL for ATV and EZE. The mean recoveries were 99.27 and 98.5% for ATV and EZE, respectively. The intermediate precision data were obtained under different experimental conditions, and the calculated value of the coefficient of variation was found to be less than the critical value. The proposed method can be useful in the quality control of bulk manufacturing and pharmaceutical dosage forms.

  2. 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

  3. 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

  4. 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

  5. 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.

  6. 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

  7. 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.

  8. 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 0.024-0.057 µg/L and 0.08-0.19 µg/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.

  9. Liquid chromatographic resolution of 1-aryl-1,2,3,4-tetrahydroisoquinolines on a chiral stationary phase based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid.

    PubMed

    Lee, Areum; Choi, Hee Jung; Jin, Kab Bong; Hyun, Myung Ho

    2011-07-01

    A liquid chromatographic chiral stationary phase (CSP) based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid was applied for the first time to the resolution of biologically important 1-aryl-1,2,3,4-tetrahydroisoquinolines. The unusual resolution of cyclic secondary amino compounds on a chiral crown ether-based CSP was quite successful with the use of a mixture of methanol-acetonitrile-triethylamine at a ratio of 30/70/0.5 (v/v/v) as a mobile phase. From the chromatographic behaviours for the resolution of seven 1-aryl-1,2,3,4-tetrahydroisoquinolines, the steric bulkiness of the 1-phenyl ring at the chiral center of analytes was concluded to play an important role in the chiral recognition.

  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

    2016-01-27

    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.

  11. 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.

  12. 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.

  13. 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.

  14. Magnetic resonance imaging of velocity fields, the void fraction and gas dynamics in a cavitating liquid

    NASA Astrophysics Data System (ADS)

    Mastikhin, Igor V.; Arbabi, Aidin; Newling, Benedict; Hamza, Abdelhaq; Adair, Alexander

    2012-01-01

    In acoustic cavitation, the relationship between the bubble dynamics on the microscale and the flow properties on the macroscale is critical in determining sonochemical reaction kinetics. A new technique was developed to measure the void fraction and estimate water mobility in the vicinity of cavitating bubbles using phase-encoded magnetic resonance imaging with short characteristic measurement timescales (0.1-1 ms). The exponential behavior of the NMR signal decay indicated the fast diffusion regime, with the relationship between local mechanical dispersion D mix and the average bubble radius R, D_mix≫ 2R^2/10^{-4s}, resulting in dispersion of orders of magnitude greater than diffusion in quiescent water. For two different samples (water and a surfactant solution), the independent measurements of three-dimensional void fraction and velocity fields permitted the calculation of compressibility, divergence and vorticity of the cavitating medium. The measured dynamics of the dissolved gas, compared with that of the surrounding liquid, reflected the difference in the bubble coalescence and lifetimes and correlated with the macroscopic flow parameters.

  15. A strategy for the systematic development of a liquid chromatographic mass spectrometric screening method for polymer electrolyte membrane degradation products using isocratic and gradient phase optimized liquid chromatography.

    PubMed

    Zedda, M; Tuerk, J; Teutenberg, T; Peil, S; Schmidt, T C

    2009-12-18

    Within the scope of research for target and non-target LC-MS/MS analysis of membrane degradation products of polymer electrolyte membrane fuel cells, a systematic method development for the separation of structurally similar compounds was performed by phase optimized liquid chromatography. Five different stationary phases with different selectivities were used. Isocratic separation for 4-hydroxybenzoic acid, isophthalic acid, terephthalic acid, 4-hydroxybenzaldehyde and 4-formylbenzoic acid was achieved on a C18 and a Phenyl phase. Using the PRISMA model the separation efficiency was optimized. This was achieved on a serially connected mixed stationary phase composed of 30 mm C18, 150 mm Phenyl and 60 mm C30. For the LC-MS screening of unknown degradation products from polymer electrolyte membranes in the product water of a fuel cell, a solvent gradient is mandatory for less polar or later eluting compounds. By means of 4-mercaptobenzoic acid it could be shown that a solvent gradient can be applied in order to elute later eluting compounds in a short time. The adaptability of this method for the qualitative analysis by target and non-target LC-MS/MS screening has been shown by means of 4-hydroxybenzoic acid. The combination of solvent gradient and isocratic conditions makes this approach attractive for the purpose of a screening method for known and unknown analytes in a water sample.

  16. 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

  17. 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.

  18. 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

  19. 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

  20. Simultaneous liquid chromatographic determination of metals and organic compounds in pharmaceutical and food-supplement formulations using evaporative light scattering detection.

    PubMed

    Spacil, Zdenek; Folbrova, Jana; Megoulas, Nikolaos; Solich, Petr; Koupparis, Michael

    2007-02-01

    A novel method for the non-derivatization liquid chromatographic determination of metals (potassium, aluminium, calcium and magnesium) and organic compounds (ascorbate and aspartate) was developed and validated based on evaporative light scattering detection (ELSD). Separation of calcium, magnesium and aluminium was achieved by the cation exchange column Dionex CS-14 and an aqueous TFA mobile phase according to the following time program: 0-6 min TFA 0.96 mL L(-1), 6-7 min linear gradient from TFA 0.96-6.4 mL L(-1). Separation of potassium, magnesium and aspartate was achieved by the lipophilic C18 Waters Spherisorb column and isocratic aqueous 0.2 mL L(-1) TFA mobile phase. Separation of sodium, magnesium, ascorbate and citrate was also achieved by the C18 analytical column, according to the following elution program: 0-2.5 min aqueous nonafluoropentanoic acid (NFPA) 0.5 mL L(-1); 2.5-3.5 min linear gradient from 0.5 mL L(-1) NFPA to 1.0 mL L(-1) TFA. In all cases, evaporation temperature was 70 degrees C, pressure of the nebulizing gas (nitrogen) 3.5 bar, gain 11 and the flow rate 1.0 mL min(-1). Resolution among calcium and magnesium was 1.8, while for all other separations was > or = 3.2. Double logarithmic calibration curves were obtained within various ranges from 3-24 to 34-132 microg mL(-1), and with good correlation (r>0.996). Asymmetry factor ranged from 0.9 to 1.9 and limit of detection from 1.3 (magnesium) to 17 microg mL(-1) (ascorbate). The developed method was applied for the assay of potassium, magnesium, calcium, aluminium, aspartate and ascorbate in pharmaceuticals and food-supplements. The accuracy of the method was evaluated using spiked samples (%recovery 95-105%, %R.S.D. < 2) and the absence of constant or proportional errors was confirmed by dilution experiments.

  1. Development and validation of a liquid chromatographic method to quantify sucrose, glucose, and fructose in tubers of Solanum tuberosum Group Phureja.

    PubMed

    Duarte-Delgado, Diana; Narváez-Cuenca, Carlos-Eduardo; Restrepo-Sánchez, Luz-Patricia; Kushalappa, Ajjamada; Mosquera-Vásquez, Teresa

    2015-01-15

    A High Performance Liquid Chromatography (HPLC) method was developed and validated to quantify sucrose (non-reducing sugar), glucose, and fructose (reducing sugars) in raw tubers of Solanum tuberosum Group Phureja. Chromatographic analysis was performed using an AMINEX HPX 87H column, at 18 °C, linked to a refraction index detector, at 35 °C. The eluent was 10mM sulfuric acid. The conditions established for the method provided an optimum separation of sugars, citric acid, and malic acid, with resolution values higher or equal to one. Among the four sugar extraction methods tested, the double 50% (v/v) aqueous methanol extraction gave the highest level of analytes. Recovery of this extraction method ranged between 94.14 and 99.77%. The HPLC method was validated for repeatability, reproducibility, linearity, and limits of detection, and quantification. Relative standard deviation was found to be lower than five, when testing repeatability and reproducibility, which is suitable considering a range of acceptability from 5.3 to 7.3. Additionally, the regression analyses supported the method linearity in a range of quantification from 3 to 100 mg/L with regression coefficients values greater than 0.998 for the three analytes. Limits of detection were 3.0 mg/L for the three sugars and limits of quantification were 2.0 mg/L for sucrose and 3.0 mg/L for glucose and fructose. Four Colombian commercial cultivars (Criolla Guaneña, Criolla Paisa, Criolla Galeras, and Criolla Colombia) and five landrace accessions from the Colombian Core Collection of Group Phureja were grown in the district of Usme (Bogotá) fields to analyze their sugar contents. Sucrose, glucose, and fructose contents were found ranging from 0.93 to 3.11 g/100 g tuber dried weight (DW), from 0.25 to 4.53 g/100 g tuber DW, and from 0.10 to 1.49 g/100 g tuber DW, respectively. Therefore, a high range in the variability of sugar contents was found among genotypes. However, the variability was low among

  2. 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

  3. Simultaneous liquid chromatographic determination of metals and organic compounds in pharmaceutical and food-supplement formulations using evaporative light scattering detection.

    PubMed

    Spacil, Zdenek; Folbrova, Jana; Megoulas, Nikolaos; Solich, Petr; Koupparis, Michael

    2007-02-01

    A novel method for the non-derivatization liquid chromatographic determination of metals (potassium, aluminium, calcium and magnesium) and organic compounds (ascorbate and aspartate) was developed and validated based on evaporative light scattering detection (ELSD). Separation of calcium, magnesium and aluminium was achieved by the cation exchange column Dionex CS-14 and an aqueous TFA mobile phase according to the following time program: 0-6 min TFA 0.96 mL L(-1), 6-7 min linear gradient from TFA 0.96-6.4 mL L(-1). Separation of potassium, magnesium and aspartate was achieved by the lipophilic C18 Waters Spherisorb column and isocratic aqueous 0.2 mL L(-1) TFA mobile phase. Separation of sodium, magnesium, ascorbate and citrate was also achieved by the C18 analytical column, according to the following elution program: 0-2.5 min aqueous nonafluoropentanoic acid (NFPA) 0.5 mL L(-1); 2.5-3.5 min linear gradient from 0.5 mL L(-1) NFPA to 1.0 mL L(-1) TFA. In all cases, evaporation temperature was 70 degrees C, pressure of the nebulizing gas (nitrogen) 3.5 bar, gain 11 and the flow rate 1.0 mL min(-1). Resolution among calcium and magnesium was 1.8, while for all other separations was > or = 3.2. Double logarithmic calibration curves were obtained within various ranges from 3-24 to 34-132 microg mL(-1), and with good correlation (r>0.996). Asymmetry factor ranged from 0.9 to 1.9 and limit of detection from 1.3 (magnesium) to 17 microg mL(-1) (ascorbate). The developed method was applied for the assay of potassium, magnesium, calcium, aluminium, aspartate and ascorbate in pharmaceuticals and food-supplements. The accuracy of the method was evaluated using spiked samples (%recovery 95-105%, %R.S.D. < 2) and the absence of constant or proportional errors was confirmed by dilution experiments. PMID:17386552

  4. Liquid chromatographic mass spectrometric (LC/MS/MS) determination of plasma hydroxocobalamin and cyanocobalamin concentrations after hydroxocobalamin antidote treatment for cyanide poisoning.

    PubMed

    Schwertner, Harvey A; Valtier, Sandra; Bebarta, Vikhyat S

    2012-09-15

    Cyanide poisoning occurs in individuals after fire smoke inhalation and after oral ingestion of cyanide. Hydroxocobalamin (HOCbl), a hydroxylated form of vitamin B(12), is often used as an antidote to treat cyanide toxicity. It has a high affinity for cyanide and rapidly removes cyanide from tissue by forming cyanocobalamin (CNCbl). Little information is available on the pharmacokinetics of HOCbl and CNCbl largely because of the lack of analytical methods for analyzing HOCbl and CNCbl. In this study, we developed a new liquid chromatographic mass spectrometric (LC/MS/MS) method for the quantitative analysis of plasma HOCbl and CNCbl in the porcine (Sus scrofa) model. The method uses on-column extraction, reversed phase gradient chromatography, and multiple reaction monitoring (MRM) for quantitation. MRM transitions monitored were 664.7→147.3 and 664.7→359.2 for HOCbl and 678.8→147.3, 678.8→359.1 678.8→457.1 for CNCbl. The limit of detection (LOD) and the lower limit of quantitation (LLOQ) were 1.0 and 1.0 μmole/L, respectively, for plasma HOCbl and 0.1 and 0.5 μmole/L for plasma CNCbl. The within-day and between-day CVs were 4.3 and 6.4% for plasma HOCbl at 500.0 μmole/L and 5.5 and 5.7% for CNCbl at 100.0 μmole/L (n=6). The plasma HOCbl and CNCbl calibrations curves were linear from 100.0 to 2000.0 and 50.0 to 500.0 μmole/L, respectively. Based on 6 separate calibration curves the average linear regression coefficient (R(2)) for both HOCbl and CNCbl was 0.992. The LC/M/MS method was found to be accurate and precise and has been validated by determining the plasma HOCbl and CNCbl concentrations in 11 pigs that were treated with HOCbl for cyanide poisoning.

  5. Liquid chromatographic determination of benzo[a]pyrene at part-per-billion concentrations in highly refined coal- and petroleum-derived fuels.

    PubMed

    Tomkins, B A; Griest, W H

    1987-01-16

    Benzo[a]pyrene (BaP), a well-known carcinogen, is frequently measured as an "indicator" of the potential dermal tumorigenicity of a sample. The present sequential high-performance liquid chromatography--high-performance liquid chromatography method overcomes problems in trace-level sample enrichment and recovery corrections encountered earlier. An amount of 5 g of naphtha or fuel oil is diluted to 10 ml with dichloromethane and spiked with a small quantity (ca. 0.25 micrograms) of 14C-labeled BaP tracer. A BaP-enriched fraction is obtained from a 1-ml aliquot of this sample by semipreparative chromatography on a Partisil PAC 10 column with dichloromethane-hexane (10:90) as the eluent, and concentrated to exactly 0.3, 0.5, or 1.0 ml in acetonitrile. Quantitation is performed using a reversed-phase Vydac 201 TP 5415 column with acetonitrile-water (75:25) as eluent and a Waters Model 420 E/420 AC fluorescence detector, employing an excitation/emission filter pair of 360/425 nm. The recovery of the radiolabeled tracer is evaluated by combustion of 50 microliter of the final isolate in pure oxygen, collection of the liberated 14CO2 in an alkaline desorber, and liquid scintillation counting. The recovery of BaP normally exceeded 90%, but values as low as ca. 50% were occasionally observed. Potential matrix interferences in the recovery determination were eliminated by sample combustion. The nominal precision of the overall method is approximately +/- 30% relative standard deviation at a BaP concentration of 30 ppb. The nominal analysis time for a single sample is approximately 4 h. PMID:3558598

  6. High-performance liquid chromatographic separation of rolipram, bupivacaine and omeprazole using a tartardiamide-based stationary phase influence of flow rate and temperature on the enantioseparation.

    PubMed

    da Silva Junior, Ivanildo José; Sartor, João Paulo; Rosa, Paulo César Pires; de Veredas, Vinícius; Barreto Júnior, Amaro Gomes; Santana, Cesar Costapinto

    2007-08-24

    Chromatographic separation of the chiral drugs rolipram, bupivacaine and omeprazole on a tartardiamide-based stationary phase commercially named Kromasil CHI-TBB is shown in this work. The effect of temperature on the chromatographic separation of the chiral drugs using the Kromasil CHI-TBB stationary phase was determined quantitatively so as to contribute toward the design for the racemic mixtures of the named compound by using chiral columns. A decrease in the retention and selectivity factors was observed, when the column temperature increased. Van't Hoff plots provided the thermodynamic data. The variation of the thermodynamic parameters enthalpy and entropy are clearly negative meaning that the separation is enthalpy controlled.

  7. Characterization of the volatile fraction emitted by Pinus spp. by one- and two-dimensional chromatographic techniques with mass spectrometric detection.

    PubMed

    Mateus, E; Barata, R C; Zrostlíková, Jitka; Gomes da Silva, M D R; Paiva, M R

    2010-03-12

    The chemical composition of the needles of P. pinea, P. pinaster, P. halepensis, P. nigra, P. brutia, P. patula, P. radiata, P. taeda, P. elliotti, P. kesiya, P. sylvestris and P. eldarica was investigated. Headspace solid-phase microextraction and steam distillation extraction were used to collect the volatile fractions. Samples were analyzed using one-dimensional gas chromatography (1D-GC) and comprehensive two-dimensional gas chromatography (GCxGC) associated with a quadrupole and a time-of-flight mass detectors. Results showed that the analytical capabilities of 1D-GC are partially limited by the separation power of the columns. The higher sensibility and the absence of peak skewing of the time-of-flight mass analyzer, with the use of automated peak finding and deconvolution algorithms, allowed for the detection of trace components with qualitative full spectra and the extraction of true mass spectra from coeluting compounds, promoting their reliable identification and thus significantly improving results obtained by 1D-GC/MS, when using a quadrupole mass analyzer. The use of GC x GC resulted in enhanced separation efficiency and increased signal to noise ratio (sensitivity) of the analytes, maximizing mass spectra quality and improving compound detection and identification. This work shows the use of 1D-GC/ToFMS for the analysis of pine needles volatiles, achieving the detection of 177 compounds, that is more than twice the number previously identified by standard 1D-GC/MS. The analysis by GC x GC for the same sample allowed the detection of 212 compounds. The enantioselective GC x GC analysis performed for all the Pinus spp. under study achieved the detection of 422 different compounds. Cross-over phenomena according to operational conditions are highlighted and discussed.

  8. On-farm treatment of swine manure based on solid-liquid separation and biological nitrification-denitrification of the liquid fraction.

    PubMed

    Riaño, B; García-González, M C

    2014-01-01

    In some regions, intensive pig farming has led to soil and water pollution due to the over-application of manure as an organic fertilizer, thereby necessitating alternative treatment technologies to help manage the large amounts of manure generated. The present study seeks to determine the effectiveness of an on-farm swine manure treatment plant consisting of a solid-liquid separation phase using screw pressing followed by a coagulation-flocculation process, and nitrification-denitrification of the liquid fraction. Each treatment unit was evaluated for its contribution towards reducing the raw manure concentration of solids, organic matter, nutrients (nitrogen and phosphorous), metals, and pathogens. The overall system presented high removal efficiencies of up to 71% of TS (total solids) and 97% of TCOD (total chemical oxygen demand). Approximately 97% TKN (total Kjeldahl nitrogen) and 89% TP (total phosphorous) removal was achieved. Metals (copper and zinc) diminished in the liquid fraction to non-detectable concentrations (<1.0 mg L(-1)). As regards microbial removal, total concentration reductions of 3.6 log10 for Escherichia coli and 1.8 log10 for Salmonella were achieved. Finally, the system was evaluated from a financial standpoint. Results indicate that screw pressing and coagulation-flocculation for solid-liquid separation and nitrification-denitrification of the liquid fraction is a technological alternative for reducing the environmental impact of intensive pig farming in a given area.

  9. 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

  10. 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

  11. Simulation of light attenuation within fluorescent microspheres used for liquid fraction separation recorded by a CSLM

    NASA Astrophysics Data System (ADS)

    Liljeborg, Anders

    1996-04-01

    In order to separate different proteins, liquid chromatography is often used. The sample is pumped through a column filled with microspheres. The velocity of the proteins are depending on their interaction with the microspheres. The proteins could be labelled with a fluorescent marker and the distribution of the protein within the sphere can be recorded using a CSLM. When collecting optical sections using a CSLM the detected intensity decreases the deeper in the specimen the section is collected. This is due to absorption, scattering and bleaching. For the special case of a single microsphere it is of interest to find out how this combined effect is distributed within the sphere for a certain distribution of the fluorescent stain. When this distribution is known the attenuation can be compensated for. In the simulation the distribution of the stain is supposed to be the result of a diffusion process and all attenuation is supposed to arise from absorption only. The attenuation for a certain volume element (voxel) is supposed to occur from absorption in the voxels above, within the cone formed by the focused excitation light beam. A basic assumption is that the attenuation within each voxel is a fraction of the fluorescent intensity within that same voxel. A simulation program has been written where the parameters of the diffusion process within the microsphere can be controlled. Also the parameters for the attenuation calculation can be set, e.g. the assumed fraction of fluorescent intensity that act as attenuation. 3D datasets can be generated for visualization. Also intensity profiles can be generated along a diameter of the simulated sphere in the depth direction, since the intensity distribution is circularly symmetric in the lateral directions. Some comparisons are made to real microspheres, and the parameters are adjusted for closest resemblance. This adjustment can be done manually but an implementation using non-linear fitting of data is also presented. The

  12. 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

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. C₁₈-bound porous silica monolith particles as a low-cost high-performance liquid chromatography stationary phase with an excellent chromatographic performance.

    PubMed

    Ali, Faiz; Cheong, Won Jo

    2014-12-01

    Ground porous silica monolith particles with an average particle size of 2.34 μm and large pores (363 Å) exhibiting excellent chromatographic performance have been synthesized on a relatively large scale by a sophisticated sol-gel procedure. The particle size distribution was rather broad, and the d(0.1)/d(0.9) ratio was 0.14. The resultant silica monolith particles were chemically modified with chlorodimethyloctadecylsilane and end-capped with a mixture of hexamethyldisilazane and chlorotrimethylsilane. Very good separation efficiency (185,000/m) and chromatographic resolution were achieved when the C18 -bound phase was evaluated for a test mixture of five benzene derivatives after packing in a stainless-steel column (1.0 mm × 150 mm). The optimized elution conditions were found to be 70:30 v/v acetonitrile/water with 0.1% trifluoroacetic acid at a flow rate of 25 μL/min. The column was also evaluated for fast analysis at a flow rate of 100 μL/min, and all the five analytes were eluted within 3.5 min with reasonable efficiency (ca. 60,000/m) and resolution. The strategy of using particles with reduced particle size and large pores (363 Å) combined with C18 modification in addition to partial-monolithic architecture has resulted in a useful stationary phase (C18 -bound silica monolith particles) of low production cost showing excellent chromatographic performance.

  19. Development and validation of an ultra high-performance liquid chromatographic method for the determination of a diastereomeric impurity in (+)-pinoresinol diglucoside chemical reference substance.

    PubMed

    Song, Jing-Zheng; Cheung, Lok Man; Liu, Xin; Qiao, Chun-Feng; Zhou, Yan; Li, Song-Lin; Chen, Shi-Lin; Xu, Hong-Xi

    2010-07-01

    (+)-Pinoresinol 4,4'-di-O-beta-D-glucopyranoside ((+)-PDG) is one of the major lignans with various pharmacological activities which could be isolated from Duzhong and other plant species. In this study, a diastereomeric impurity, (-)-pinoresinol 4,4'-di-O-beta-D-glucopyranoside ((-)-PDG), the main impurity was identified in (+)-PDG chemical reference substance (CRS) and a reliable chromatographic method for rapid purity determination of (+)-PDG CRS was firstly developed. The optimal chromatographic condition was found to be using ACN/1,4-dioxane-water (2.5:6:91.5, v/v/v) as mobile phase on a Waters Acquity UPLC HSS T3 column (2.1 mm x 100 mm, 1.8 microm) with column temperature of 37 degrees C. The method was validated and applied to determine the chromatographic purity of five (+)-PDG CRS samples. The content of (-)-PDG in four commercial (+)-PDG CRS was 8.47-20.30%, whereas no (-)-PDG was detected in our in-house prepared (+)-PDG CRS in which purity was confirmed to be 99.80%. The above results confirmed that this method is fast and highly efficient for purity determination of the (+)-PDG CRS.

  20. 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.

  1. Fractional Spin Fluctuations as a Precursor of Quantum Spin Liquids: Majorana Dynamical Mean-Field Study for the Kitaev Model

    NASA Astrophysics Data System (ADS)

    Yoshitake, Junki; Nasu, Joji; Motome, Yukitoshi

    2016-10-01

    Experimental identification of quantum spin liquids remains a challenge, as the pristine nature is to be seen in asymptotically low temperatures. We here theoretically show that the precursor of quantum spin liquids appears in the spin dynamics in the paramagnetic state over a wide temperature range. Using the cluster dynamical mean-field theory and the continuous-time quantum Monte Carlo method, which are newly developed in the Majorana fermion representation, we calculate the dynamical spin structure factor, relaxation rate in nuclear magnetic resonance, and magnetic susceptibility for the honeycomb Kitaev model whose ground state is a canonical example of the quantum spin liquid. We find that dynamical spin correlations show peculiar temperature and frequency dependence even below the temperature where static correlations saturate. The results provide the experimentally accessible symptoms of the fluctuating fractionalized spins evincing the quantum spin liquids.

  2. Rapid screening of mycotoxins in liquid milk and milk powder by automated size-exclusion SPE-UPLC-MS/MS and quantification of matrix effects over the whole chromatographic run.

    PubMed

    Wang, Xiupin; Li, Peiwu

    2015-04-15

    An automated, size-exclusion solid phase extraction (SPE)-UPLC-MS/MS protocol without pre-treatment of samples was developed to screen for four mycotoxins (OTA, ZEN, AFB1, and AFM1) in liquid milk and milk powder. Firstly, a mixed macropore-silica gel cartridge was established as a size-exclusion SPE column. The proposed methodology could be a candidate in green analytical chemistry because it saves on manpower and organic solvent. Permanent post-column infusion of mycotoxin standards was used to quantify matrix effects throughout the chromatographic run. Matrix-matched calibration could effectively compensate for matrix effects, which may be caused by liquid milk or milk powder matrix. Recovery of the four mycotoxins in fortified liquid milk was in the range 89-120% and RSD 2-9%. The LOD for the four mycotoxins in liquid milk and milk powder were 0.05-2 ng L(-1) and 0.25-10 ng kg(-1), respectively. The LOQ for the four mycotoxins in liquid milk and milk powder were 0.1-5 ng L(-1) and 0.5-25 ng kg(-1), respectively.

  3. Chromatographic methods in the study of autism.

    PubMed

    Żurawicz, Ewa; Kałużna-Czaplińska, Joanna; Rynkowski, Jacek

    2013-10-01

    Research into biomarkers of autism is a new means of medical intervention in this disease. Chromatographic techniques, especially coupled with mass spectrometry, are widely used in determination of biomarkers and assessment of effectiveness of autism therapy owing to their sensitivity and selectivity. Among the chromatographic techniques gas chromatography and liquid chromatography, especially high-performance liquid chromatography, have found application in clinical trials. The high-performance liquid chromatography technique allows an analysis of liquid samples with a wide range of molecules, small and large, providing an opportunity to perform advanced assays within a short time frame. Gas chromatography with the appropriate preparation of samples (gaseous and liquid) and a selection of analysis conditions enables the separation of thermally stable, volatile and non-volatile organic substances in short runtimes. The chromatographic techniques that are currently used in metabolic studies in autism are designed to identify abnormalities in three areas: the metabolism of neurotransmitters, nutritional and metabolic status and manifestations of oxidative stress. This review presents a necessary theoretical introduction and examples of applications of chromatographic studies of disorder markers in autism.

  4. Microbial communities in liquid and fiber fractions of food waste digestates are differentially resistant to inhibition by ammonia.

    PubMed

    Peng, Wei; Lü, Fan; Shao, Liming; He, Pinjing

    2015-04-01

    The effect of different concentrations of ammonia (1.0-7.0 g/L) during mesophilic anaerobic digestion with fiber or liquid digestate as inoculum was examined. Evolution of microbial community within fiber and liquid digestates was quantitatively assessed by the intact lipid analysis methods and qualitatively by DNA fingerprint methods in order to determine their resistance to ammonia inhibition. The results showed that an increased level of total ammonia nitrogen prolonged the lag phase of fiber digestates while reduced the metabolic rate of liquid digestates. Fiber digestates had 19.6-50.9-fold higher concentrations of phospholipid fatty acids (PLFA) compared to liquid digestates, whereas concentrations of phospholipid ether lipids (PLEL) in the fiber digestates were only 2.91-17.6-fold higher compared to liquid digestates. Although the cell concentration in liquid fraction was far lower than that in the fiber one, the ammonia-resistant ability and the methanization efficiency of the liquid digestate was superior to the fiber digestate. The bacterial profiles were affected more by the type of digestate inoculum compared to the concentration of ammonia. Principal component analysis indicated that the lipids technique was superior to the DNA technique for bacterial quantification but detected less archaeal diversity. PMID:25661818

  5. 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.

  6. UPLC and LC-MS studies on degradation behavior of irinotecan hydrochloride and development of a validated stability-indicating ultra-performance liquid chromatographic method for determination of irinotecan hydrochloride and its impurities in pharmaceutical dosage forms.

    PubMed

    Kumar, Navneet; Sangeetha, Dhanaraj; Reddy, Sunil P

    2012-10-01

    The objective of the current investigation was to study the degradation behavior of irinotecan hydrochloride under different International Conference on Harmonization (ICH) recommended stress conditions using ultra-performance liquid chromatography and liquid chromatography-mass spectrometry and to establish a validated stability-indicating reverse-phase ultra-performance liquid chromatographic method for the quantitative determination of irinotecan hydrochloride and its seven impurities and degradation products in pharmaceutical dosage forms. Irinotecan hydrochloride was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Irinotecan hydrochloride was found to degrade significantly in oxidative and base hydrolysis and photolytic degradation conditions. The degradation products were well resolved from the main peak and its impurities, thus proving the stability-indicating power of the method. Chromatographic separation was achieved on a Waters Acquity BEH C8 (100 × 2.1 mm) 1.7-µm column with a mobile phase containing a gradient mixture of solvent A (0.02M KH(2)PO(4) buffer, pH 3.4) and solvent B (a mixture of acetonitrile and methanol in the ratio of 62:38 v/v). The mobile phase was delivered at a flow rate of 0.3 mL/min with ultraviolet detection at 220 nm. The run time was 8 min, within which irinotecan and its seven impurities and degradation products were satisfactorily separated. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. This method was also suitable for the assay determination of irinotecan hydrochloride in pharmaceutical dosage forms.

  7. Liquid chromatographic enantioseparation of (RS)-mexiletine and (RS)-fluoxetine using chiral derivatizing reagents synthesized with (S)-naproxen moiety.

    PubMed

    Batra, Sonika; Bhushan, Ravi

    2014-06-01

    Enantiomeric separation of racemic mexiletine and fluoxetine was achieved using three chiral derivatizing reagents (CDRs) based on (S)-naproxen. Diastereomers were synthesized by reaction of mexiletine or fluoxetine with the CDRs and were separated on a C18 column under reversed-phase conditions using a binary mixture of acetonitrile and triethylammonium phosphate/water, with UV detection at 230 and 226 nm. The results obtained for enantioseparation of the two drugs using the three CDRs were compiled and compared. The conditions for derivatization and chromatographic separation were optimized. The method was validated for linearity, repeatability, limit of detection and limit of quantification. PMID:24861749

  8. 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.

  9. Gas-liquid chromatographic detection an determination of diacetyl tartaric acid ester of diglyceride in dairy and nondairy coffee cream powders.

    PubMed

    Inoue, T; Iwaida, M; Ito, Y; Tonogai, Y

    1981-03-01

    Diacetyl tartaric acid ester of diglyceride was directly extracted from dairy or nondairy coffee cream powder under acidic conditions with ethyl acetate; then the extract was saponified with methanolic potash. After acidification with HCl, free fatty acid was removed with ether and the reaction mixture was absorbed on an anion exchange column. Tartaric acid was eluted with 2N HCl-acetone (1+1). An aliquot of the trimethylsilyl (TMS) derivative of the eluate was injected into a gas chromatograph with flame ionization detection, and a 1.5% SE-30 column. Recoveries of diacetyl tartaric acid ester of diglyceride at 50, 200, and 2000 ppm were 85.6-99.5%.

  10. 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.

  11. 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.

  12. 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

  13. Liquid collection in sidewall crystallization of magma: A comment on ``liquid fractionation. Part I'', by A.R. McBirney, B.H. Baker and R.H. Nilson

    NASA Astrophysics Data System (ADS)

    Morse, S. A.

    1986-11-01

    The term liquid fractionation is inappropriate for a process driven by crystallization; liquid collection is proposed instead. The amount of evolved residual liquid produced by sidewall crystallization is not greater than that produced by any perfect fractional crystallization process and the fractionation products must be balanced somewhere by less evolved crystal deposits. There is no free lunch in petrology. Sidewall heating limits the local duration of liquid collection and the complementary crystal products should be sought in conduits. Flux ratios rather than diffusivities control the differences between thermal and chemical boundary layers.

  14. 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.

  15. Investigation on the preparation and chromatographic behavior of a new para-tert-butylcalix[4]arene-1,2-crown-4 stationary phase for high performance liquid chromatography.

    PubMed

    Hu, Kai; Zhao, Wenjie; Wen, Fuyong; Liu, Junwei; Zhao, Xiaolan; Xu, Zhanhui; Niu, Bailin; Ye, Baoxian; Wu, Yangjie; Zhang, Shusheng

    2011-07-15

    In the present work, a new para-tert-butylcalix[4]arene-1,2-crown-4 bonded silica stationary phase (CBS4-4) was synthesized, structurally characterized, and employed to separate polycyclic aromatic hydrocarbons (PAHs), phenols, aromatic amines, benzoic acid and its derivatives. The chromatographic behaviors of the prepared stationary phase were investigated and compared with ODS. The effects of methanol concentrations on the retention index show that CBS4-4 exhibits high selectivity for the above analytes. The separation mechanisms based on the different interactions between calixarene and the analytes were discussed. With the assistance of quantum chemistry calculation, the interaction Gibbs free energy change ΔG(solv) (in the mobile phase) of p, m and o-phenylenediamine positional isomers and para-tert-butylcalix[4]arene-1,2-crown-4 were obtained. The ΔG(solv) values were consistent with the retention behavior of p, m and o-phenylenediamine on the CBS4-4. According to the chromatographic data, it can be concluded that the selectivity of CBS4-4 for analytes is mainly ascribed to hydrophobic interaction, accompanied by other effects such as hydrogen bonding interaction, π-π and inclusion interaction. The CBS4-4 column has been successfully employed for the analysis of benzoic acid in Sprite drink. PMID:21645705

  16. Multi-wavelength high-performance liquid chromatographic fingerprints and chemometrics to predict the antioxidant activity of Turnera diffusa as part of its quality control.

    PubMed

    Lucio-Gutiérrez, J Ricardo; Garza-Juárez, Aurora; Coello, J; Maspoch, S; Salazar-Cavazos, M L; Salazar-Aranda, Ricardo; Waksman de Torres, Noemi

    2012-04-27

    The determination of the antioxidant activity of Turnera diffusa using partial least squares regression (PLSR) on chromatographic data is presented. The chromatograms were recorded with a diode array detector and, for each sample, an enhanced fingerprint was constructed by compiling into a single data vector the chromatograms at four wavelengths (216, 238, 254 and 345 nm). The wavelengths were selected from a contour plot, in order to obtain the greater number of peaks at each of the wavelengths. A further pretreatment of the data that included baseline correction, scaling and correlation optimized warping was performed. Optimal values of the parameters used in the warping were found by means of simplex optimization. A PLSR model with four latent variables (LV) explained 52.5% of X variance and 98.4% of Y, with a root mean square error for cross validation of 6.02. To evaluate its reliability, it was applied to an external prediction set, retrieving a relative standard error for prediction of 7.8%. The study of the most important variables for the regression indicated the chromatographic peaks related to antioxidant activity at the used wavelengths. PMID:22405537

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. Improved high-performance liquid chromatographic method for the determination of domoic acid and analogues in shellfish: effect of pH.

    PubMed

    López-Rivera, A; Suárez-Isla, B A; Eilers, P P; Beaudry, C G; Hall, S; Fernández Amandi, M; Furey, A; James, K J

    2005-04-01

    Domoic acid (DA) is a naturally-occurring amino acid that causes a form of human intoxication called amnesic shellfish poisoning (ASP) following the consumption of shellfish. A rapid and sensitive HPLC-UV method has been developed for analysis of DA and analogues in shellfish without the need for SPE clean-up. Isocratic chromatographic separation of DA and its isomers from shellfish matrix interferences and from the prevalent amino acid, tryptophan, was achieved by careful control of the mobile phase pH. The optimised pH was found to be 2.5 when using a Luna(2) C18 column. Sample extraction was verified with control extracts from shellfish spiked at 5.0 and 10.0 microg/g of DA and with certified reference material. The average extraction efficiency was 98.5%. The calibration, based on mussel tissue spiked with DA standard, was linear in the range 0.05-5.0 microg/ml (r = 0.9999) and the detection limit (signal:noise 3:1) was better than 25 ng/ml. The DA assay achieved good precision; %RSD = 1.63 (intra-day, n = 6) and %RSD = 3.7 (inter-day, n = 8). This method was successfully applied to a variety of shellfish species, allowing the rapid screening of a large number of samples per day (20-30), without the need for SPE clean-up. Quantitative data were obtained for shellfish samples containing domoic acid in the concentration range 0.25-330 microg/g. Using the same chromatographic conditions, LC-MS3 was used to determine DA and its isomers, isodomoic acid D and epi-domoic acid, in scallop tissues. PMID:15770470

  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. High-performance liquid chromatography of amino acids, peptides and proteins. CXXIX. Ceramic-based particles as chemically stable chromatographic supports.

    PubMed

    Wirth, H J; Eriksson, K O; Holt, P; Aguilar, M; Hearn, M T

    1993-08-27

    Porous zirconia based particles have been modified using different derivatisation procedures. The modified particles were characterised in terms of their accessible surface areas and degree of surface coverage of the bounded or physicoated phases utilising the strong and specific adsorption of phosphate ions to the zirconia surface. The hydroxyl group density was determined by a 1H NMR technique. The particles were modified by immobilising different silanes to introduce either hydrophobic ligands or reactive groups onto the zirconia surface. In the latter case, various ligands were then covalently attached to the activated supports. Using this type of modification, n-octadecyl- (C18), carbohydrate- and Cibacron Blue F3GA-modified zirconia particles were produced. Furthermore, polymeric coated particles were prepared either by using polybutadiene or by cross-linking the carbohydrate modified sorbents. The pH stability of the different sorbents were determined in batch experiments and under chromatographic conditions. The leakage of ligands was monitored by UV absorption and by employing radioactively labelled ligands. The performance of the C18 reversed-phase modified zirconia in packed columns was also used as an indicator of changes in the surface chemistry following pH stability tests. The experimental results indicate that the Cibacron Blue F3GA dye-modified sorbent was stable up to pH 10.5, the C18 reversed-phase packing up to pH 13 and the carbohydrate-bonded phase up to pH 12. These investigations substantiate the favourable chemical and physical characteristics anticipated for surface modified zirconias for potential use as chromatographic adsorbents. PMID:8408421

  7. 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.

  8. 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

  9. 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.

  10. Half-width plots, a simple tool to predict peak shape, reveal column kinetics and characterise chromatographic columns in liquid chromatography: state of the art and new results.

    PubMed

    Baeza-Baeza, J J; Ruiz-Ángel, M J; García-Álvarez-Coque, M C; Carda-Broch, S

    2013-11-01

    Peak profiles in chromatography are characterised by their height, position, width and asymmetry; the two latter depend on the values of the left and right peak half-widths. Simple correlations have been found between the peak half-widths and the retention times. The representation of such correlations has been called half-width plots. For isocratic elution, the plots are parabolic, although often, the parabolas can be approximated to straight-lines. The plots can be obtained with the half-widths/retention time data for a set of solutes experiencing the same kinetics, eluted with a mobile phase at fixed or varying composition. When the analysed solutes experience different resistance to mass transfer, the plots will be solute dependent, and should be obtained with the data for each solute eluted with mobile phases at varying composition. The half-width plots approach is a simple tool that facilitates the prediction of peak shape (width and asymmetry) with optimisation purposes, reveal the interaction kinetics of solutes in different columns, and characterise chromatographic columns. This work shows half-width plots for different situations in isocratic elution, including the use of different flows, the effect of temperature, the modification of the stationary phase surface by an additive, the existence of specific interactions within the column, and the comparison of columns. The adaptation to gradient elution is also described. Previous knowledge on half-width plots is structured and analysed, to which new results are added.

  11. Chromatographic efficiency comparison of polyhedral oligomeric silsesquioxanes-containing hybrid monoliths via photo- and thermally-initiated free-radical polymerization in capillary liquid chromatography for small molecules.

    PubMed

    Wang, Hongwei; Ou, Junjie; Liu, Zhongshan; Lin, Hui; Peng, Xiaojun; Zou, Hanfa

    2015-09-01

    Monolithic poly(methacrylate epoxy cyclosiloxane-co-polyhedral oligomeric silsesquioxanes) (epoxy-MA-POSS) capillary columns have been prepared via either photo- or thermally-initiated polymerization of the corresponding monomers using a 1-propanol/PEG 400 mixture as porogens. Photochemical polymerization was accomplished by irradiation of the UV-transparent capillary for 10min at room temperature, while thermal polymerization was performed at 55°C, 60°C or 65°C for 18h. The evaluation of chromatographic property for two hybrid epoxy-MA-POSS monoliths was carried out. The results indicate that hybrid monoliths fabricated by photochemical initiation exhibit higher column efficiency (97,000-98,400plates/m) than those synthesized by thermal polymerization (41,100-48,000plates/m) in cLC. The higher efficiency of photo-initiated hybrid monoliths is closely related to lower eddy dispersion (A-term) and mass transfer resistance (C-term).

  12. 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.

  13. 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.

  14. High-performance liquid chromatographic assay to determine the plasma levels of HIV-protease inhibitors (amprenavir, indinavir, nelfinavir, ritonavir and saquinavir) and the non-nucleoside reverse transcriptase inhibitor (nevirapine) after liquid-liquid extraction.

    PubMed

    Dailly, E; Thomas, L; Kergueris, M F; Jolliet, P; Bourin, M

    2001-07-15

    A single HPLC assay was developed for therapeutic drug monitoring of 5 HIV protease inhibitors (indinavir, amprenavir, saquinavir, ritonavir, nelfinavir) and a non-nucleoside reverse transcriptase inhibitor (nevirapine) in human plasma. After liquid-liquid extraction in a mixture ethyl acetate-hexane, compounds are separated on a C18 column with a gradient elution of solvent A [acetonitrile and 0.025 M tetramethylammonium perchlorate in 0.2% aqueous trifluoroacetic acid (55:45 (v/v))] and solvent B [methanol and 0.025 M tetramethylammonium perchlorate in 0.2% aqueous trifluoroacetic acid (55:45 (v/v))]. The compounds are detected at various wavelengths: 320 nm (nevirapine), 259 nm (indinavir), 254 nm (amprenavir, nelfinavir, saquinavir) and 239 nm (ritonavir). The intra-day and inter-day precision and accuracy are lower than 15%. The limits of quantitation are 0.05 mg/l (amprenavir), 0.2 mg/l (indinavir, saquinavir, nelfinavir) and 0.4 mg/l (ritonavir, nevirapine). This method which allows to estimate simultaneously plasma levels of protease inhibitors and nevirapine can be used for therapeutic drug monitoring.

  15. 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

  16. Combined use of algorithms for peak picking, peak tracking and retention modelling to optimize the chromatographic conditions for liquid chromatography-mass spectrometry analysis of fluocinolone acetonide and its degradation products.

    PubMed

    Fredriksson, Mattias J; Petersson, Patrik; Axelsson, Bengt-Olof; Bylund, Dan

    2011-10-17

    A strategy for rapid optimization of liquid chromatography column temperature and gradient shape is presented. The optimization as such is based on the well established retention and peak width models implemented in software like e.g. DryLab and LC simulator. The novel part of the strategy is a highly automated processing algorithm for detection and tracking of chromatographic peaks in noisy liquid chromatography-mass spectrometry (LC-MS) data. The strategy is presented and visualized by the optimization of the separation of two degradants present in ultraviolet (UV) exposed fluocinolone acetonide. It should be stressed, however, that it can be utilized for LC-MS analysis of any sample and application where several runs are conducted on the same sample. In the application presented, 30 components that were difficult or impossible to detect in the UV data could be automatically detected and tracked in the MS data by using the proposed strategy. The number of correctly tracked components was above 95%. Using the parameters from the reconstructed data sets to the model gave good agreement between predicted and observed retention times at optimal conditions. The area of the smallest tracked component was estimated to 0.08% compared to the main component, a level relevant for the characterization of impurities in the pharmaceutical industry.

  17. 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

  18. Oxygen Isotope Fractionation During Evaporation of Mg- and Si-rich CMAS-Liquids in Vacuum

    NASA Astrophysics Data System (ADS)

    Mendybaev, R. A.; Richter, F. M.; Spicuzza, M. J.; Valley, J. W.; Davis, A. M.

    2010-03-01

    We report oxygen isotope data for the residues produced by evaporation of Mg- and Si-rich CMAS-liquids. The results on oxygen together with Mg- and Si-isotopes in the experimental run products are used to estimate the isotopic compositions of natural FUN CAIs.

  19. A transient method for measuring the gas volume fraction in a mixed gas-liquid flow using acoustic resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Dehua; Wang, Xiuming; Che, Chengxuan; Cong, Jiansheng; Xu, Delong; Wang, Xiaomin

    2010-08-01

    In this paper, the feasibility of measuring the gas volume fraction in a mixed gas-liquid flow by using an acoustic resonant spectroscopy (ARS) method in a transient way is studied theoretically and experimentally. Firstly, the effects of sizes and locations of a single air bubble in a cylindrical cavity with two open ends on resonant frequencies are investigated numerically. Then, a transient measurement system for ARS is established, and the trends of the resonant frequencies (RFs) and resonant amplitudes (RAs) in the cylindrical cavity with gas flux inside are investigated experimentally. The measurement results by the proposed transient method are compared with those by steady-state ones and numerical ones. The numerical results show that the RFs of the cavity are highly sensitive to the volume of the single air bubble. A tiny bubble volume perturbation may cause a prominent RF shift even though the volume of the air bubble is smaller than 0.1% of that of the cavity. When the small air bubble moves, the RF shift will change and reach its maximum value as it is located at the middle of the cavity. As the gas volume fraction of the two-phase flow is low, both the RFs and RAs from the measurement results decrease dramatically with the increasing gas volume, and this decreasing trend gradually becomes even as the gas volume fraction increases further. These experimental results agree with the theoretical ones qualitatively. In addition, the transient method for ARS is more suitable for measuring the gas volume fraction with randomness and instantaneity than the steady-state one, because the latter could not reflect the random and instant characteristics of the mixed fluid due to the time consumption for frequency sweeping. This study will play a very important role in the quantitative measurement of the gas volume fraction of multiphase flows.

  20. 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.