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Sample records for liquid chromatographic fractions

  1. Liquid chromatographic fractionation of small peptides from wine.

    PubMed

    Desportes, C; Charpentier, M; Duteurtre, B; Maujean, A; Duchiron, F

    2000-10-06

    Peptides are difficult to isolate from wine because they are present in a complex mixture together with non-peptidic compounds. A method for the isolation, separation and purity assessing of small peptides is proposed. Small peptides (Mr<3000) were isolated from wine by hollow fibre ultrafiltration followed by column chromatography using the gel matrix Sephadex LH20. Fractions obtained by gel filtration on Sephadex LH20 were subjected to HPLC on a porous graphitic carbon column in order to isolate small peptides. Peak purity was then analysed by capillary electrophoresis.

  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are also being used at the pilot scale to purify the human blood products superoxide dismutase and hemoglobin from outdated red blood cells.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. Using the liquid-chromatographic-fingerprint of sterols fraction to discriminate virgin olive from other edible oils.

    PubMed

    Bagur-González, M G; Pérez-Castaño, E; Sánchez-Viñas, M; Gázquez-Evangelista, D

    2015-02-06

    A method to discriminate virgin olive oil from other edible vegetable oils such as, sunflower, pomace olive, rapeseed, canola, corn and soybean, applying chemometric techniques to the liquid chromatographic representative fingerprint of sterols fraction, is proposed. After a pre-treatment of the LC chromatogram data - including baseline correction, smoothing signal and mean centering - different unsupervised and supervised pattern recognition procedures, such as principal component analysis (PCA), hierarchical cluster analysis (HCA), and partial least squares-discriminant analysis (PLSDA), have been applied. From the information obtained from PCA and HCA, two groups can be clearly distinguished (virgin olive and the rest of vegetable oils tested) which have been used to discriminate between two defined classes by means of a PLSDA model. Five latent variables (LVs) explained 76.88% of X-block variance and 95.47% of the defined classes block (γ-block) variance. A root mean square error for calibration and cross validation of 0.10 and 0.22 respectively, confirmed these results and a root mean square error for prediction of 0.15 evidences that the classification model proposed presents an adequate prediction capability. The contingency table also shows the good performance of the model, proving the capability of the LC-R-FpM, to discriminate virgin olive from other vegetable edible oils. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Microcarbon residue yield and heteroatom partitioning between volatiles and solids for whole vacuum resids and their liquid chromatographic fractions

    SciTech Connect

    Green, J.B.; Shay, J.Y.; Reynolds, J.W.; Green, J.A.; Young, L.L.; White, M.E.

    1993-10-01

    Five petroleum >1000{degrees}F resids were separated into compound type fractions using liquid chromatography. The coking tendency of each compound type was assessed using the microcarbon residue (MCR) test (ASTM D 4530). Heteroatom (N, S, Ni, V) partitioning between MCR solids versus volatiles was determined through analysis of the starting fractions and the corresponding MCR solids. The weighted sum of MCR solid yields over all compound types in a given resid was typically in good agreement with the MCR yield of the whole resid. This finding agrees with prior studies indicating coke yield to be an additive property. Sulfur partitioning was also an additive property, was predictable from MCR yield, and was nearly independent of the initial form (sulfide, thiophenic, sulfoxide) present. Nitrogen and nickel partitioning were nonadditive and therefore composition dependent. Partitioning of vanadium into solids was essentially quantitative for all resids and their fractions. MCR solid yield was generally dependent only on H/C ratio. However, there is some evidence indicating secondary dependence on hydrocarbon structure; i.e., that naphthenic rings reduce MCR in proportion to H/C by virtue of their effective hydrogen transfer properties. Deposition of N and Ni into MCR solids over the fractions was often appreciably less than that of the whole resids, thereby indicating that interaction among various compound types was required for maximum incorporation of those elements into coke.

  11. Liquid Chromatographic Analysis of Hydraulic Fluids.

    DTIC Science & Technology

    1979-11-01

    ADOO36 ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN 9* F/s 7/4 LIQUID CHROMATOGRAPHIC ANALYSIS OF HYDRAULIC FLUIDS. (U) I NOV 79 & L...HABNAUER, 9 M DOWSEI UNCLASSIFIED AMMRC-TR-79-57 ML 2.EhhhEh MOOSO fllllfffflllfff AMMRC TR 79-57 ALWI i e LIQUID CHROMATOGRAPHIC ANALYSIS o.;OF HYDRAULIC...methods Liquid chromatography Quality control Chemical analysis 20. ABSTRACT (Continue en reverse aidet it necoserr end identifly by block number) (SEE

  12. Isolation of polychlorinated dibenzodioxins and polychlorinated dibenzofurans from a complex organic mixture by two-step liquid chromatographic fractionation for quantitative analysis

    SciTech Connect

    Tong, H.Y.; Shore, D.L.; Karasek, F.W.

    1984-11-01

    Polychlorinated dibenzodioxins (PCDD) and polychlorinated dibenzofurans (PCDF) are present with several hundred organic compounds in raw fly ash extract. A first-step normal-phase semipreparative high-pressure liquid chromatography (HPLC) fractionation with a three-solvent gradient elution program separates PCDD and PCDF into a single fraction with about 100 other components. The PCDD and PCDF in this fraction are further isolated from the accompanying compounds by a second-step HPLC fractionation using a reverse-phase semipreparative column and a two-solvent gradient elution program. The distribution of PCDD and PCDF into five subfractions facilitates isomer identification and their quantitation. The separation of PCDD and PCDF by this procedure shows high recovery and good reproducibility.

  13. 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.

  14. 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.

  15. 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".

  16. 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.

  17. Liquid chromatographic determination of melamine in beverages.

    PubMed

    Ishiwata, H; Inoue, T; Yamazaki, T; Yoshihira, K

    1987-01-01

    A liquid chromatographic method is described for the determination of melamine in beverages. Melamine is separated by column chromatography using cation and anion exchange resin and determined by ion-pair liquid chromatography using an ODS column and a mixture of acetonitrile and 0.05M phosphate buffer (pH 3.0) containing 0.005M sodium 1-laurylsulfate (1 + 4, v/v) as mobile phase. Recoveries of melamine ranged between 90.3 +/- 7.8 and 102.1 +/- 5.6% at levels of 0.6 to 2.4 ppm in 4 kinds of beverages. The quantitation limit was 2.5 micrograms melamine in 50 mL beverage. The method was applied to the migration test of melamine from melamine-formaldehyde resin products to the beverages.

  18. 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.

  19. 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.

  20. Multiresidue determination of beta-lactam antibiotics in milk and tissues with the aid of high-performance liquid chromatographic fractionation for clean up.

    PubMed

    Moats, W A; Romanowski, R D

    1998-07-03

    Screening of milk shipments for beta-lactam antibiotic residues is mandatory in the USA and is widely used in other countries. Interpretation of positive screening test results has been difficult. Only six beta-lactam antibiotics are approved for use in food-producing animals in the USA but many others are used in other countries. A multiresidue procedure was developed for identification and quantitation of unknown beta-lactam antibiotics. The residues were extracted with acetonitrile and tetraethylammonium chloride. The extract was concentrated by evaporation and filtered. The concentrated extract was then loaded onto an HPLC column in 100% 0.01 M KH2PO4 and eluted with an acetonitrile gradient. Fractions corresponding to analytes of interest were collected and tested for antibiotics using rapid milk screening tests. Fractions testing positive were analyzed by HPLC. The identity of beta-lactams was confirmed by treating a replicate with beta-lactamase.

  1. Full and fractionated experimental designs for robustness testing in the high-performance liquid chromatographic analysis of codeine phosphate, pseudoephedrine hydrochloride and chlorpheniramine maleate in a pharmaceutical preparation.

    PubMed

    Ragonese, R; Mulholland, M; Kalman, J

    2000-02-18

    This paper describes the testing of a saturated factorial design using a full factorial design. Saturated factorial designs are often used to test the robustness of high-performance liquid chromatography (HPLC) methods, however they are based on several assumptions. A full factorial design relies on fewer assumptions and hence could be used to evaluate the effectiveness of the saturated design. Both designs were used to test a gradient HPLC method for the assay of codeine phosphate, pseudoephedrine hydrochloride and chlorpheniramine maleate. Six HPLC conditions, including wavelength, mobile phase pH and ion pairing reagent concentration were tested using the saturated design. Three of these factors were selected for full evaluation using a full factorial design. The results showed that the main effects calculated by each design were comparable. However, the saturated design showed higher standard errors, probably due to the effects of changing several more factors. One interaction effect was indicated as a confounding effect by the saturated design and this was confirmed by the calculation of the same interaction effect using the full design. Overall the method was shown to be robust under the variety of HPLC conditions tested.

  2. 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. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  3. Comparison of three liquid chromatographic methods for egg-white protein analysis.

    PubMed

    Awadé, A C; Efstathiou, T

    1999-02-19

    This paper describes and compares three chromatographic methods for the analysis of egg-white proteins. Gel-permeation chromatography allowed the separation of seven peaks from egg white, with an almost total protein recovery. A clean separation of ovomucin and lysozyme from the bulk of the proteins was obtained with this method. Reversed-phase high-performance liquid chromatography led to the fractionation of at least eight peaks. With this chromatographic method, the recovery was relatively poor. Approximately 30% of the ovalbumin was retained in the column after the elution. Finally, eleven chromatographic peaks were separated from egg white by high-performance liquid chromatography on an anion-exchange column. The recovery of proteins was almost total. The latter method afforded higher resolution.

  4. Quantitative liquid chromatographic analysis of anthracyclines in biological fluids.

    PubMed

    Maudens, Kristof E; Stove, Christophe P; Lambert, Willy E

    2011-09-01

    Anthracyclines are amongst the most widely used drugs in oncology, being part of the treatment regimen in most patients receiving systemic chemotherapy. This review provides a comprehensive summary of the sample preparation techniques and chromatographic methods that have been developed during the last two decades for the analysis of the 4 most administered anthracyclines, doxorubicin, epirubicin, daunorubicin and idarubicin in plasma, serum, saliva or urine, within the context of clinical and pharmacokinetic studies or for assessing occupational exposure. Following deproteinization, liquid-liquid extraction, solid phase extraction or a combination of these techniques, the vast majority of methods utilizes reversed-phase C18 stationary phases for liquid chromatographic separation, followed by fluorescence detection, or, more recently, tandem mass spectrometric detection. Some pros and cons of the different techniques are addressed, in addition to potential pitfalls that may be encountered in the analysis of this class of compounds. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Development of High Pressure Liquid Chromatographic Techniques

    DTIC Science & Technology

    1976-05-01

    grinding . 22 Table 1. Response of Beta-Induced Luminescence Detection System to Nitrogen- and Halogen-Containing Organic Compounds Liquid Sample...Haemopexin and Trans- ferrin," .’. of Chromatogr. , 84, 1973, pp. 87-94. Rao, G. H. R., jnd Anders, M. W., " Aflatoxin Detection by ^’igh-Speed Liq. Chrom

  6. 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.

  7. [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.

  8. 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.

  9. Basicity of aromatic amines from liquid chromatographic behavior

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  10. Isolation and Characterization of Fractions of Mycoplasma pneumoniae I. Chemical and Chromatographic Separation

    PubMed Central

    Prescott, B.; Sobeslavsky, O.; Caldes, G.; Chanock, R. M.

    1966-01-01

    Prescott, B. (National Institute of Allergy and Infectious Diseases, Bethesda, Md.), O. Sobeslavsky, G. Caldes, and R. M. Chanock. Isolation and characterization of fractions of Mycoplasma pneumoniae. I. Chemical and chromatographic separation. J. Bacteriol. 91:2117–2125. 1966.—Fractionation of Mycoplasma pneumoniae, cultured on a beef heart infusion-horse serum-yeast extract medium, was carried out by chemical and chromatographic procedures. The chemical method yielded eight fractions consisting of lipid, carbohydrates, and proteins. Four protein-rich fractions were isolated by chromatographing a supernatant fluid of sonically treated organisms on Sephadex G-25. The 12 fractions were tested for serological and antigenic activity in vitro and in vivo. The lipid fraction was serologically active and the relative order of activity of the protein fractions appeared to depend on the amount of lipid present in the molecule. The highly serologically active Sephadex G-25 protein fraction 1 prepared chromatographically contained 15% lipid in the molecule, whereas the less serologically active protein fraction 2 prepared by chemical means contained 2% lipid. The acetone-extracted lipid fraction was chromatographed on thin-layer chromatography plates and found to consist of nine fractions. Serological activity was associated with only the first three spots above the origin. Lipid extracted from the protein fractions seemed to be similar to the acetone-extracted lipid from the sediment of the sonically treated organisms. PMID:5943931

  11. [High-performance liquid chromatographic determination of propanidid and etomidate].

    PubMed

    Zawisza, P; Przyborowski, L

    1992-01-01

    High-performance reversed-phase liquid chromatographic determination of propanidid and etomidate was performed on ODS silica, after precipitation of the proteins in plasma with methanol, extraction of the drugs with diethyl ether, evaporation and dissolving in a mobile phase: acetonitrile-phosphate buffer pH 4.44 (7:3, v/v); UV detection at 254 nm. Dionine hydrochloride was used as an internal standard. Propanidid was determined in a range 5-25 microg/cm3 of plasma and etomidate in 0.1-0.5 microg/cm3 of plasma, thus enables the analysis of therapeutic levels of the drugs.

  12. Liquid chromatographic determination of pyrantel tartrate in medicated formulations.

    PubMed

    Konrardy, Joyce A; Burner, Mary A; Garner, Tommy W; Litchman, Mark A; Webster, Gregory K

    2003-01-01

    The validation of a novel liquid chromatographic (LC) method for the determination of pyrantel tartrate in feed is presented. The method provides a significant improvement over the efficiency and precision of AOAC Official Method 978.30. The method was shown to be accurate, precise, linear, and robust for medicated articles. Unlike the official method, the LC method was shown to be a superior stability-indicating method. After the method was validated by using laboratory blends, the effectiveness of the method was demonstrated with marketed product as well.

  13. Quantum Spin Liquids and Fractionalization

    NASA Astrophysics Data System (ADS)

    Misguich, Grégoire

    This chapter discusses quantum antiferromagnets which do not break any symmetries at zero temperature - also called "spin liquids" - and focuses on lattice spin models with Heisenberg-like (i.e. SU(2)-symmetric) interactions in dimensions larger than one. We begin by discussing the Lieb-Schultz-Mattis theorem and its recent extension to D > 1 by Hastings (2004), which establishes an important distinction between spin liquids with an integer and with a half-integer spin per unit cell. Spin liquids of the first kind, "band insulators", can often be understood by elementary means, whereas the latter, "Mott insulators", are more complex (featuring "topological order") and support spin-1/2 excitations (spinons). The fermionic formalism (Affleck and Marston, 1988) is described and the effect of fluctuations about mean-field solutions, such as the possible creation of instabilities, is discussed in a qualitative way. In particular, we explain the emergence of gauge modes and their relation to fractionalization. The concept of the projective symmetry group (X.-G. Wen, 2002) is introduced, with the aid of some examples. Finally, we present the phenomenology of (gapped) short-ranged resonating-valence-bond spin liquids, and make contact with the fermionic approach by discussing their description in terms of a fluctuating Z 2 gauge field. Some recent references are given to other types of spin liquid, including gapless ones.

  14. 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

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

    PubMed

    Martinez, E E; Shimoda, W

    1988-01-01

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

  16. High-pressure liquid chromatographic method for analysis of cephalosporins.

    PubMed Central

    Signs, S A; File, T M; Tan, J S

    1984-01-01

    A high-pressure liquid chromatographic method is described for the analysis of a wide range of cephalosporin congeners, using only three reagents for extraction and drug analysis. Plasma was treated with cold methanol-0.1 M sodium acetate to precipitate protein. Cephalosporins were resolved on a C-18 reverse-phase column, utilizing a mobile phase of various percentages of 0.01 M sodium acetate and acetonitrile-methanol. Compounds analyzed included cephalexin, cefamandole, cephalothin, cefotaxime, cefazolin, cephaloridine, cefoxitin, cefaclor, cephapirin, and cefoperazone. Each antibiotic demonstrated excellent linearity throughout the therapeutic range. The method of standard additions revealed recoveries of 93 to 101%, with detection limits ranging from 0.2 to 1.0 micrograms/ml for these drugs. Retention times ranged from 4 to 6 min. This method offers a rapid and simple means by which this group of cephalosporins may be reliably quantitated. PMID:6517553

  17. 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.

  18. Liquid chromatographic determination of sennosides in Cassia angustifolia leaves.

    PubMed

    Srivastava, Alpuna; Pandey, Richa; Verma, Ram K; Gupta, Madan M

    2006-01-01

    A simple liquid chromatographic method was developed for the determination of sennosides B and A in leaves of Cassia angustifolia. These compounds were extracted from leaves with a mixture of methanol-water (70 + 30, v/v) after defatting with hexane. Analyte separation and quantitation were achieved by gradient reversed-phase liquid chromatography and UV absorbance at 270 nm using a photodiode array detector. The method involves the use of an RP-18 Lichrocart reversed-phase column (5 microm, 125 x 4.0 mm id) and a binary gradient mobile-phase profile. The various other aspects of analysis, namely, peak purity, similarity, recovery, repeatability, and robustness, were validated. Average recoveries of 98.5 and 98.6%, with a coefficient of variation of 0.8 and 0.3%, were obtained by spiking sample solution with 3 different concentration solutions of standards (60, 100, and 200 microg/mL). Detection limits were 10 microg/mL for sennoside B and 35 microg/mL for sennoside A, present in the sample solution. The quantitation limits were 28 and 100 microg/mL. The analytical method was applied to a large number of senna leaf samples. The new method provides a reliable tool for rapid screening of C. angustifolia samples in large numbers, which is needed in breeding/genetic engineering and genetic mapping experiments.

  19. Comprehensive two-dimensional liquid chromatographic analysis of anthocyanins.

    PubMed

    Willemse, Chandré M; Stander, Maria A; Tredoux, Andreas G J; de Villiers, André

    2014-09-12

    Anthocyanins are naturally occurring plant pigments whose accurate analysis is hampered by their complexity and unique chromatographic behaviour associated with on-column conversion reactions. This paper reports the evaluation of off-line comprehensive two-dimensional liquid chromatography (LC×LC) for the analysis of anthocyanins. Hydrophilic interaction chromatography (HILIC) was used in the first dimension in combination with reversed phase liquid chromatography (RP-LC) in the second dimension. For the selective detection of anthocyanins, diode array detection was used, while high resolution quadrupole-time-of-flight mass spectrometry (Q-TOF) was used for compound identification. As application, the HILIC×RP-LC separation of diverse anthocyanins in blueberries, red radish, black beans, red grape skins and red cabbage is demonstrated. Off-line HILIC×RP-LC revealed information which could not be obtained by one-dimensional HPLC methods, while the structured elution order for the anthocyanins simplifies compound identification and facilitates the comparison of anthocyanin content of natural products by means of contour plots.

  20. Liquid chromatographic determination of RH-5992, an ecdysone agonist, in some forestry matrixes.

    PubMed

    Sundaram, K M; Zhu, J; Nott, R

    1993-01-01

    A liquid chromatographic method is described for the analysis of RH-5992 (N'-t-butyl-N'-[3,5-dimethyl-benzoyl]-N- [-ethylbenzoyl]hydrazine) from various terrestrial and aquatic forestry matrixes and stream water. The processed soils, litter, oak foliage, sediment, aquatic plants, and fish were extracted with a mixture of acetone and water; balsam fir needles were extracted with acidified methanol solution; stream water was extracted with dichloromethane. Aliquots of crude extracts were solvent partitioned, concentrated, and cleaned up by using Florisil or Prepsep-NH2 columns. After fractional elution of the columns with hexane-ethyl acetate as the eluent, the eluates were analyzed on a liquid chromatograph equipped with a diode-array UV detector set at 236 nm, using an RP-8, 10 microns column with a mobile phase of acetonitrile-dioxane-water. Fir needles required methanol in addition to the 3 solvents in the mobile phase mixture. Water samples did not require any column cleanup. Mean recoveries for the analyte ranged from 84 to 98%, with coefficients of variation from 5 to 10%. Limits of detection (LOD) and limits of quantitation (LOQ) ranged from 0.004 to 0.030 ppm and from 0.013 to 0.101 ppm, respectively, for various forestry matrixes. LOD and LOQ for natural waters were 0.050 and 0.166 ppb, respectively.

  1. Liquid chromatographic determination of progestogens in animal fat.

    PubMed

    Andresen, M T; Fesser, A C

    1996-01-01

    A liquid chromatographic method was developed for determination of 3 progestogens-melengestrol acetate, megestrol acetate, and chlormadinone acetate-found in edible tissue at concentrations between 10 and 1000 ppb. These progestogens are commonly used as feed additives to control herd estrus and to improve feed efficiency. Rendered fat was extracted with acetonitrile, washed with hexane, and dried. The remaining lipids were saponified with sodium hydroxide and precipitated with magnesium chloride. The progestogens were extracted from the basic solution with hexane, dried, and cleaned up on a cyanopropyl solid-phase extraction column in the normal-phase mode. The eluate was dried and reconstituted with acetonitrile-water (7 + 3, v/v). Chromatography was performed on a 5 microns high-carbon load C18 column with acetonitrile-water (7 + 3, v/v) at 1 mL/min and UV detection at 291 nm. Recoveries from fortified samples ranged from 84 to 116%. The limit of quantitation was 10 ppb for both beef and pork. The detection limit was 3 ppb.

  2. Liquid chromatographic determination of beta-naphthoxyacetic acid in tomatoes.

    PubMed

    Gökmen, V; Acar, J

    1998-03-06

    An alternative high-performance liquid chromatographic method for the determination of beta-naphthoxyacetic acid (BNOA) in tomatoes is described. BNOA was extracted from tomatoes with acetone-dichloromethane (2:1). The extract was cleaned up by Bio-Beads S-X3 gel-permeation chromatography and by partitioning. A reversed-phase C18 column was used for HPLC analysis. The mobile phase was acetonitrile-2% acetic acid in water (50:50, v/v) pumped at a flow-rate of 1.0 ml/min. Retention time of BNOA was ca. 7 min with a percentage coefficient of variation of 0.71. Resolution of BNOA was good on the column. Percentage recoveries of BNOA were 79.5 +/- 6.82, 94.8 +/- 2.70 and 86.4 +/- 16.43 for the corresponding spiking levels of 0.5, 1.0 and 2.0 micrograms per g tomato, respectively. Analysis of 10 greenhouse tomato samples from local markets in Ankara showed no BNOA residue.

  3. Liquid chromatographic analysis of oxytocin and its related substances.

    PubMed

    Ashenafi, Dunge; Van Hemelrijck, Elise; Chopra, Shruti; Hoogmartens, Jos; Adams, Erwin

    2010-01-05

    A selective gradient liquid chromatographic (LC) method for the determination of oxytocin (OT) and its related substances in bulk drugs has been developed. The method uses a reversed-phase C18 column (25 cm x 4.0 mm i.d.), 5 microm kept at 40 degrees C. The mobile phases consist of acetonitrile, dihydrogen phosphate solution pH 4.4 and water. The flow rate is 1.0 ml/min. UV detection is performed at 220 nm. A system suitability test (SST) was developed to govern the quality of the separation. The separation towards OT components was investigated on different C18 columns. The developed method was further validated with respect to robustness, precision, sensitivity and linearity. A central composite design was applied to examine the robustness of the method. The method shows good precision, sensitivity, linearity and robustness. Two commercial OT samples were examined using this method. Furthermore, the method proved to be successful when applied to analyze a marketed OT formulation for injection.

  4. 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...

  5. Reversed-phase liquid chromatographic determination of cromolyn sodium in drug substance and select dosage forms.

    PubMed

    Ng, L L

    1994-01-01

    This study, presented as a technical communication, describes a reversed-phase liquid chromatographic method for select commercial formulations, namely, inhalation solution, nasal solution, capsule and inhalation aerosol. Miscellaneous validation parameters are also discussed.

  6. Liquid chromatographic methods for biotransformation studies of ochratoxin A.

    PubMed

    Schaut, A; De Saeger, S; Sergent, T; Schneider, Y-J; Larondelle, Y; Pussemier, L; Blank, R; Van Peteghem, C

    2008-09-01

    Liquid chromatographic methods were used for the detection of ochratoxin A (OTA) and its metabolites ochratoxin alpha (OTalpha), 10-hydroxy OTA (10-OHOTA), 4R-hydroxy OTA (4R-OHOTA) and the ethyl ester of OTA (OTC) in in vitro samples, obtained with Caco-2 cell culture experiments and in in vivo urine samples from sheep. A high-performance liquid chromatography method with fluorescence detection (HPLC-FLD) and a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method were developed and validated for the detection of OTA and its metabolites OTalpha, 10-OHOTA, 4R-OHOTA and OTC, which was used as internal standard. The LOD/LOQ values for OTalpha, 4R-OHOTA and OTA were 0.63/2.11, 0.99/3.31 and 0.84/2.81 microg/L, respectively, for the HPLC-FLD method and 0.98/3.28, 1.11/3.72 and 0.88/2.96 microg/L, respectively for the LC-MS/MS method. Within-day and between-day precision were both <12% for the HPLC-FLD method, and <10% for the LC-MS/MS method. The recovery of OTA and its metabolites ranged between 71 and 111% for the HPLC-FLD method and between 79 and 110% for the LC-MS/MS method. In the first experiment only OTA was added to the Caco-2 cells while in the second experiment 3-methylcholanthrene (3MC) was also present in the cell culture systems. Besides OTA, which was recovered in all the samples, an unknown compound was also observed in the second experiment. When 3MC was added, the results showed that the OTA concentration in the basolateral samples was decreased by 50%. The methods were also implemented for the analysis of urine samples of sheep, fed increasing amounts of OTA. With the HPLC-FLD method it could be concluded that the concentration of OTA and OTalpha increased according to ingested amounts of OTA, with OTalpha being the most abundant compound. The results obtained with the LC-MS/MS method confirmed these results.

  7. 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.

  8. Estimation of the vapor pressure of petroleum distillate fractions from gas chromatographic data

    SciTech Connect

    Eggertsen, F.T.; Nygard, N.R.; Nickoley, L.D.

    1980-11-01

    The vapor pressure of petroleum distillate fractions is estimated conveniently by applying ideal gas and solution laws to gas chromatographic data. The vapor pressure is computed as a summation of the partial pressures for carbon number groups in the chromatogram, each partial pressure being derived as the product of mole fraction, determined from the chromatogram, and saturation pressure, calculated using the Antoine equation. A rapid method of computation with a programmable calculator was used. The method assumes approximate conformance to Raoult's and Dalton's laws relating to partial pressures from a solution. The results generally agree well with values obtained manometrically. Advantages of the method are the general availability of suitable gas chromatographic equipment, convenience and speed of the procedure and calculations, applicability over a wide range of volatility, freedom from temperature equilibration problems, and small sample requirement. 4 figures, 6 tables.

  9. Liquid chromatographic analysis of cinchona alkaloids in beverages.

    PubMed

    Horie, Masao; Oishi, Mitsuo; Ishikawa, Fusako; Shindo, Tetsuya; Yasui, Akiko; Ogino, Shuzo; Ito, Koichi

    2006-01-01

    A method for the determination of Cinchona extract (whose main components are the alkaloids cinchonine, cinchonidine, quinidine, and quinine) in beverages by liquid chromatography was developed. A beverage with an alcohol content of more than 10% was loaded onto an OASIS HLB solid-phase extraction cartridge, after it was adjusted to pH 10 with 28% ammonium hydroxide. Other beverages were centrifuged at 4000 rpm for 5 min, and the supernatant was loaded onto the cartridge. The cartridge was washed with water followed by 15% methanol, and the Cinchona alkaloids were eluted with methanol. The Cinchona alkaloids in the eluate were chromatographed on an L-column ODS (4.6 mm id x 150 mm) with methanol and 20 mmol/L potassium dihydrogen phosphate (3 + 7) as the mobile phase. Cinchona alkaloids were monitored with an ultraviolet (UV) detector at 230 nm, and with a fluorescence detector at 405 nm for cinchonine and cinchonidine and 450 nm for quinidine and quinine (excitation at 235 nm). The calibration curves for Cinchona alkaloids with the UV detector showed good linearity in the range of 2-400 microg/mL. The detection limit of each Cinchona alkaloid, taken to be the concentration at which the absorption spectrum could be identified, was 2 microg/mL. The recovery of Cinchona alkaloids added at a level of 100 microg/g to various kinds of beverages was 87.6-96.5%, and the coefficients of variation were less than 3.3%. A number of beverage samples, some labeled to contain bitter substances, were analyzed by the proposed method. Quinine was detected in 2 samples of carbonated beverage.

  10. Liquid chromatographic determination of seven antioxidants in dry food.

    PubMed

    Page, B D; Charbonneau, C F

    1989-01-01

    The liquid chromatographic determinative step of the official method for propyl gallate, trihydroxybutyrophenone, tert-butylhydroquinone, nordihydroguaiaretic acid, butylated hydroxyanisole (BHA), 3,5-di-tert-butyl-4-hydroxymethylphenol, and butylated hydroxytoluene (BHT) in fats and oils has been applied to their determination in a number of dry foods. A representative sample (10 g) is homogenized first with hexane (25 mL), then with 5 mL added water, and finally with 75 mL added acetonitrile. The hexane and acetonitrile are decanted, filtered, and separated; the hexane and rehydrated food are reextracted with 2 additional portions of acetonitrile, and the combined acetonitrile extracts are concentrated and diluted to 10 mL. An aliquot is analyzed as described in the official method, using a 150 x 4.6 mm 5 microns C-18 column. The need for rehydration to maximize the recovery of BHA and other antioxidants from marketplace dry food samples such as potato flakes, dry coffee whiteners, and dessert topping mixes was demonstrated. Rehydration was not required for cheese snacks, breakfast cereals, cake mixes, and some other foods. The need for rehydration should be determined by analyzing other foods with and without the addition of water. Potato and corn chips, popcorn and cheese snacks, breakfast cereals, dry beverage mixes, rice, potato flakes, french fried potatoes, and cake mixes were spiked with the above antioxidants at 10-50 ppm. Overall recoveries ranged from 64.3 to 105.6% and repeatabilities ranged from 0.7 to 10.8%. A total of 109 samples of the above foods were analyzed, and 64% contained detectable (greater than 1-2 ppm) antioxidants, mainly BHA and BHT.

  11. Liquid chromatographic determination of Alternaria toxins in carrots.

    PubMed

    Solfrizzo, Michele; De Girolamo, Annalisa; Vitti, Carolina; Visconti, Angelo; van den Bulk, Ruud

    2004-01-01

    A liquid chromatographic (LC) method was developed for the determination of Alternaria radicina and A. alternata toxins in carrots. Toxins were extracted from carrot with an acidified mixture of water-methanol-acetonitrile. The filtered extract was divided in 2 parts that were purified by solid-phase extraction on a C18 column for the analysis of radicinin (RAD), altertoxin-I (ATX-I), alternariol (AOH), and alternariol methyl ether (AME), and on a polymeric Oasis HLB column for tenuazonic acid (TeA). Toxins were quantified by reversed-phase LC with UV diode array detection by using 2 consecutive isocratic mixtures of acetonitrile-sodium dihydrogen phosphate solution. Mean recoveries of TeA, ATX-I, AME, RAD, and AOH from carrots spiked at levels between 0.5 and 3.0 microg/g were 69, 71, 90, 36, and 78%, with mean within-laboratory repeatability of 14, 5, 4, 6, and 18%, respectively. The mean between-laboratory reproducibilities for the determination of TeA, ATX-I, AME, and RAD in spiked samples were 25, 22, 6, and 12%, respectively. Limits of detection (signal-to-noise ratio of 3) for RAD, TeA, ATX-I, AME, and AOH were 0.006, 0.02, 0.02, 0.01, and 0.005 microg/g, respectively. RAD was detected (0.16-13.9 microg/g) in 3 out of 266 carrot samples produced under organic conditions in 3 European locations, whereas A. alternata mycotoxins were not found in any tested samples.

  12. Fractionalized Z_{2} Classical Heisenberg Spin Liquids.

    PubMed

    Rehn, J; Sen, Arnab; Moessner, R

    2017-01-27

    Quantum spin systems are by now known to exhibit a large number of different classes of spin liquid phases. By contrast, for classical Heisenberg models, only one kind of fractionalized spin liquid phase, the so-called Coulomb or U(1) spin liquid, has until recently been identified: This exhibits algebraic spin correlations and impurity moments, "orphan spins," whose size is a fraction of that of the underlying microscopic degrees of freedom. Here, we present two Heisenberg models exhibiting fractionalization in combination with exponentially decaying correlations. These can be thought of as a classical continuous spin version of a Z_{2} spin liquid. Our work suggests a systematic search and classification of classical spin liquids as a worthwhile endeavor.

  13. An electron-capture gas–liquid-chromatographic method for the determination of prostaglandin F2α in biological fluids

    PubMed Central

    Wickramasinghe, Asoka J. F.; Shaw, Robert S.

    1974-01-01

    A sensitive electron-capture gas–liquid-chromatographic method for the determination of sub-nanogram quantities of prostaglandin F2α was developed. The method is based on the sub-microgram scale conversion of the prostaglandin into the electron-capturing pentafluorobenzyl ester, and analysis of the latter as the tris-trimethylsilyl ether. The lower limit of detection was 12.5pg of the ester injected `on-column' as the silylated product. The method was successfully applied to the determination of prostaglandin F2α in monkey plasma. The specificity of the analytical procedure was increased by incorporating a thin-layer chromatographic fractionation before gas–liquid chromatography. The utility of the analytical methodology developed was demonstrated by its application to the determination of plasma concentrations of intact prostaglandin F2α in a Rhesus monkey, after subcutaneous administration of a single dose of prostaglandin F2α. The electron-capture gas–liquid-chromatographic assay is compared with the radioimmunoassay and the gas–liquid-chromatographic–mass-spectrometry assay for the determination of prostaglandin F2α. PMID:4218093

  14. 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.

  15. Fractionation and characterization of nano- and microparticles in liquid media.

    PubMed

    Fedotov, Petr S; Vanifatova, Nataliya G; Shkinev, Valery M; Spivakov, Boris Ya

    2011-06-01

    Submicron and micron particles present in liquid environmental, biological, and technological samples differ in their dimensions, shape, mass, chemical composition, and charge. Their properties cannot be reliably studied unless the particles are fractionated. Synthetic particles applied as components of analytical systems may also need preliminary fractionation and investigation. The review is focused on the methods for fractionation and characterization of nanoparticles and microparticles in liquid media, the most representative examples of their application, and the trends in developing novel approaches to the separation and investigation of particles. Among the separation techniques, the main attention is devoted to membrane filtration, field-flow fractionation, chromatographic, and capillary electrokinetic methods. Microfluidic systems employing the above-mentioned and other separation principles and providing a basis for the fabrication of lab-on-chip devices are also examined. Laser light scattering methods and other physical techniques for the characterization of particles are considered. Special attention is given to "hyphenated" techniques which enable the separation and characterization of particles to be performed in online modes.

  16. [Mutagenicity of 3 organic fractions of atmospheric dust and gas chromatographic analysis of the basic fraction].

    PubMed

    Gottlieb, A; Schleibinger, H; Ketseridis, G; Wullenweber, M; Rüden, H

    1983-01-01

    Suspended particulate matter (PM) with a Dae less than 0.4 micron was collected from July 1981 till January 1982. The ether/benzene soluble extract (EEOM) and the acidic, basic and neutral fractions were determined and investigated for their mutagenic activities in the Ames bioassay. In addition particles (Dae) less than 10.2 micron derived in January were investigated. Five compounds of the basic fraction were determined by gaschromatography. The following results were obtained: Suspended particulate matter (Dae less than 0.4 micron) and the ether/benzene extract increase from July to January. The lowest rates occur in July (PM: 16.9 micron/m3) and August (EEOM: 3.0 micrograms/m3), the highest in January (PM: 48.9 micrograms/m3, EEOM: 10.5 micrograms/m3). The ether/benzene soluble portion of the suspended particulate matter increases from the average rate of 16.3% (July-September) to 22.7% (November-January). The neutral fraction amounts to 44.9%, the acidic fraction to 27.3% and the basic fraction to 3.5% of the organic matter (on an average). In experiments with metabolic activation 99% of the total mutagenicity during the period of July till September can be demonstrated by summing up the mutagenicity of the three fractions on the other hand only 59.7% from November till January. The EEOMs derived from winter exhibit without metabolic activation (250 micrograms/plate) distinctively higher numbers of revertants than the single fractions. Dose-response curves of extracts derived from back-up filters (Dae less than 0.4 micron) in January show that the acidic fraction has a slightly higher mutagenic activity than the neutral fraction (mean values of tests with and without S9-mix). The basic fraction shows no mutagenicity without S9-mix, with activation the mutagenic activity is lower than that of the other fractions. Mutagenicity expressed as rev./m3 air shows, that the neutral fraction is most efficient. The number of revertants per plate reveals-in relation to

  17. Biodegradation kinetics of dissolved organic matter chromatographic fractions in an intermittent river

    NASA Astrophysics Data System (ADS)

    Catalán, N.; Casas-Ruiz, J. P.; von Schiller, D.; Proia, L.; Obrador, B.; Zwirnmann, E.; Marcé, R.

    2017-01-01

    Controls on the degradation of dissolved organic matter (DOM) are complex but key to understand the role of freshwaters in the carbon cycle. Both the origin and previous degradation history have been suggested to determine DOM reactivity, but it is still a major challenge to understand the links between DOM composition and biodegradation kinetics. An appropriate context to study these links are intermittent rivers, as summer drought naturally diversifies DOM sources and sinks. Here we investigated the biodegradation kinetics of DOM in the main aquatic environments present in a temporary river. During dark incubations we traced the dynamics of bulk DOM and its main chromatographic fractions defined using LC-OCD: high molecular weight substances (HMWS), low molecular weight substances (LMWS), and humic substances and building blocks. Bulk DOM decay patterns were successfully fitted to the reactivity continuum (RC) biodegradation model. The RC parameters depicted running waters as the sites presenting a more reactive DOM, and temporary pools, enriched in leaf litter, as the ones with slowest DOM decay. The decay patterns of each DOM fraction were consistent throughout sites. LMWS and HMWS decayed in all cases and could be modeled using the RC model. Notably, the dynamics of LMWS controlled the bulk DOM kinetics. We discuss the mechanistic basis for the chromatographic fractions' kinetics during biodegradation and the implications that preconditioning and summer drought can have for DOM biodegradation in intermittent rivers.

  18. [Optimization of two-dimensional high performance liquid chromatographic columns for highly efficient separation of intact proteins].

    PubMed

    Hong, Guangfeng; Gao, Mingxia; Yan, Guoquan; Guan, Xia; Tao, Qian; Zhang, Xiangmin

    2010-02-01

    In order to optimize two-dimensional liquid chromatographic (2D-LC) columns for highly efficient separation of proteins, several liquid chromatographic columns were investigated and evaluated. Weak anion-exchange (WAX) column was chosen as the first dimension because of its extensive protein separation power. By comparison of different WAX chromatographic columns for human liver protein separation, TSKgel DEAE-5PW column was selected as the first dimension of a 2D-LC system. For the second dimension, ten typical reversed-phase (RP) LC columns (250 mm x 4.6 mm, 5 microm, 30 nm) were investigated and evaluated. Their silica based RP stationary phases were butyl (C4), octyl (C8) or octadecyl (C18). To evaluate the retention behavior and non-specific protein adsorption ability of these ten columns, four neutral compounds (uracil, nitrobenzene, naphthalene and fluorene) and three standard proteins (cytochrome C, myoglobin and albumin from chicken egg white) were adopted and separated by RPLC. Meantime, WAX fractions were used to investigate the separation ability of different alkyl-bonded silica stationary phase columns for complex protein samples. By comparison of column separation efficiency, adsorption of intact proteins and sample analysis, Jupiter 300 C4 column was finally employed for its excellent separation ability. Optimization of WAX and RPLC columns offers reliable foundation for the construction of 2D-LC protein separation systems.

  19. Experimental Confirmation of Isotope Fractionation in Thiomolybdates Using Ion Chromatographic Separation and Detection by Multicollector ICPMS.

    PubMed

    Kerl, Carolin F; Lohmayer, Regina; Bura-Nakić, Elvira; Vance, Derek; Planer-Friedrich, Britta

    2017-03-07

    Molybdenum (98)Mo/(95)Mo isotope ratios are a sediment paleo proxy for the redox state of the ancient ocean. Under sulfidic conditions, no fractionation between seawater and sediment should be observed if molybdate (MoO4(2-)) is quantitatively transformed to tetrathiomolybdate (MoS4(2-)) and precipitated. However, quantum mechanical calculations previously suggested that incomplete sulfidation could be associated with substantial fractionation. To experimentally confirm isotope fractionation in thiomolybdates, a new approach for determination of isotope ratios of individual thiomolybdate species was developed that uses chromatography (HPLC-UV) to separate individual thiomolybdates, collecting each peak and analyzing isotope ratios with multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). Using commercially available MoO4(2-) and MoS4(2-) standards, the method was evaluated and excellent reproducibility and accuracy were obtained. For species with longer retention times, complete chromatographic peaks had to be collected to avoid isotope fractionation within peaks. Isotope fractionation during formation of thiomolybdates could be experimentally proven for the first time in the reaction of MoO4(2-) with 20-fold or 50-fold excess of sulfide. The previously calculated isotope fractionation for MoS4(2-) was confirmed, and the result for MoO2S2(2-) was in the predicted range. Isotopic fractionation during MoS4(2-) transformation with pressurized air was dominated by kinetic fractionation. Further optimization and online-coupling of the HPLC-MC-ICPMS approach for determination of low concentrations in natural samples will greatly help to obtain more accurate species-selective isotope information.

  20. 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.

  1. Simultaneous high-performance liquid chromatographic determination of suxibuzone and its metabolites in plasma and urine.

    PubMed

    Marunaka, T; Shibata, T; Minami, Y; Umeno, Y; Shindo, T

    1980-11-01

    A high-performance liquid chromatographic method is described for the simultaneous determination of the anti-inflammatory agent suxibuzone and its metabolites, 4-hydroxymethylphenylbutazone, phenylbutazone, oxyphenbutazone, and gamma-hydroxyphenylbutazone, in plasma and urine. Acidified plasma or urine is extracted with benzenecyclohexane (1:1). The organic extract is reduced to dryness and the resulting residue is redissolved in methanol. Aliquots of this solution are chromatographed on a reversed-phase column using a mobile phase of methanol--0.5 M KH2PO4 (linear gradient from 0 to 100% methanol at 8% min with a flow rate of 2.0 ml/min) on a high-performance liquid chromatograph equipped with a UV absorbance detector (254 nm). Detection is limited to 0.10 microgram/ml for suxibuzone and 4-hydroxymethylphenylbutazone and to 0.05 microgram/ml for the other metabolites.

  2. Reversed-phase liquid chromatographic separation and simultaneous profiling of steroidal glycoalkaloids and their aglycones.

    PubMed

    Kuronen, P; Väänänen, T; Pehu, E

    1999-11-19

    Improved and simplified reversed-phase liquid chromatographic conditions for the separation and simultaneous profiling of both steroidal glycoalkaloids and their aglycones, having solanidane- or spirosolane-type structures, are described. The most reproducible retention behavior for these ionizable compounds on C18 columns was achieved under isocratic and gradient elution conditions using acetonitrile in combination with triethylammonium phosphate buffer at pH 3.0, when basic functional groups of solutes and silanol groups on the silica are fully protonated minimizing ionic interactions. Gradient elution was the only feasible approach for the simultaneous separation of steroidal glycoalkaloids and their aglycones. A Zorbax SB C18 column, specially designed for low-pH separations, showed good performance in critical separations. The impurities of the commercial tomatine and tomatidine standards were studied and confirmed using mass spectrometric, liquid chromatographic and thin-layer chromatographic methods.

  3. Liquid chromatographic assay of diatrizoic acid and its diiodo degradation products in radio-opaque solutions

    SciTech Connect

    Farag, S.A.

    1995-03-01

    A liquid chromatographic method is described for the analysis of diatrizoic acid (2,4,6-triiodo-3,5-diacetamidobenzoic acid) and its 2,4- and 2,6-diiodo degradation products in radio-opaque injection solutions. The method is accurate, precise, and linear at a concentration range of 5-50 ppm. 12 refs., 6 figs., 5 tabs.

  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. Liquid chromatographic method for perphenazine and its sulfoxide in pharmaceutical dosage forms for determination of stability.

    PubMed

    Beaulieu, N; Lovering, E G

    1986-01-01

    A liquid chromatographic method is described for determination of perphenazine and perphenazine sulfoxide in representative dosage forms. Sulfoxide levels were nondetectable or less than 1% in tablets and in an injectable product. Sulfoxide levels increase with time in some syrup formulations and may be as high as 11% in syrup formulations before their expiration date.

  6. 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...

  7. Simultaneous liquid chromatographic determination of water-soluble vitamins, caffeine, and preservative in oral liquid tonics.

    PubMed

    Maeda, Y; Yamamoto, M; Owada, K; Sato, S; Masui, T; Nakazawa, H

    1989-01-01

    A rapid, simple, and reliable liquid chromatographic method has been developed for the simultaneous determination of nicotinamide (niacinamide), thiamine, riboflavin, riboflavin sodium phosphate, pyridoxine, caffeine, and sodium benzoate in commercial oral liquid tonics. The 7 components are separated on a reverse phase C18 column using a mobile phase of acetonitrile-0.01M potassium dihydrogen phosphate-triethylamine (8 + 91.5 + 0.5 v/v/v) containing 5mM sodium octanesulfonate and adjusted to pH 2.8 with phosphoric acid. Components are detected at 254 nm with attenuation 0.02 AUFS. Acetanilide is used as an internal standard. In addition to the 7 components mentioned, nicotinic acid (niacin), cyanocobalamin, and folic acid are also separated under the same conditions. Sample preparation involves only addition to internal standard solution and dilution with mobile phase and then filtration. Recoveries of the 7 components and cyanocobalamin from spiked preparations ranged from 97 to 104% with coefficients of variation of 0.9-4.2%.

  8. Quantitative high-performance liquid chromatographic determination of acrolein in plasma after derivatization with Luminarin 3.

    PubMed

    Paci, A; Rieutord, A; Guillaume, D; Traoré, F; Ropenga, J; Husson, H P; Brion, F

    2000-03-10

    A rapid, sensitive and specific high-performance liquid chromatographic method for the quantification of acrolein (1), one of the toxic metabolites of oxazaphosphorine alkylating agents (cyclophosphamide and ifosfamide) was developed. Condensation of acrolein with Luminarin 3 afforded a fluorescent derivative that could be specifically detected and quantified. Chromatographic conditions involved a C18 RP column Uptisphere and a gradient elution system to optimize resolution and time analysis. The method showed high sensitivity with a limit of detection of 100 pmol/ml and a limit of quantification of 300 pmol/ml. This technique is particularly suitable for pharmacokinetic studies on plasma of oxazaphosphorine-receiving patients.

  9. Liquid chromatographic profiles of individual compounds of technical toxaphene.

    PubMed

    Vetter, W; Costas, N P; Bartha, R; Martínez, A G; Luckas, B

    2000-07-21

    The elution orders of 20 hexa- to nonachlorobornanes and five hexa- to octachlorocamphenes were studied with normal-phase silica and amino phase HPLC, reversed-phase HPLC, as well as gel-permeation chromatography (GPC). Twenty-one compounds of technical toxaphene (CTTs) are commercially available and four were isolated from environmental samples. Structure-activity relationships and chromatographic properties were deduced from the data sets derived on these LC systems. The retention on silica (low-resolution LC and HPLC) increased with the polarity of the CTTs. The elution order of CTTs on amino normal-phase HPLC was, for the most part, the same as on silica normal-phase HPLC. The degree of chlorination determined the elution order of CTTs on C18 RP-HPLC. CTTs eluted from medium-pressure GPC with decreasing molecular size. Chlorobornanes with dichloro substituents on the six-membered ring eluted after the chloroboranes without geminal chlorine atoms on secondary carbons, indicating that these congeners are larger. Altogether, the results increase the knowledge of complex substance class and may serve as a tool in order to gain further standard components.

  10. A Gas-Liquid Chromatographic Examination of Stilbene Derivatives

    Treesearch

    Richard W. Hemingway; W. E. Hillis; K Burerton

    1970-01-01

    Trimethylsilyl ether derivatives of twenty hydroxystilbenes were separated by gas-liquid chromatography on Apiezon-L, OV-1, OV-17, and SE-54. Relative retention times were highly dependent upon the degree of hydroxylation and methoxylation, the positions of these groups and on cis-trans...

  11. 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.

  12. Separation and purification of uridine diphosphate-glucuronosyltransferases by chromatofocusing on a high-performance liquid chromatograph.

    PubMed

    Takanashi, H; Homma, H; Matsui, M

    1989-06-01

    A rapid method for the separation and purification of uridine diphosphate-glucuronosyltransferases (GT) was developed with the use of chromatofocusing on a high-performance liquid chromatograph. GT isoenzymes solubilized from hepatic microsomes of Wistar rats were separated on a Mono P column, a pre-packed column for chromatofocusing. Using 4-nitrophenol, testosterone and androsterone as substrates, four fractions with different GT activities were separated in a pH gradient from 9.5 to 7.0. Two isoenzymes, testosterone GT and androsterone GT were purified to apparent homogeneity. They were eluted at pH 8.9 and 8.0 and had subunit molecular weight values of 50000 and 52000, respectively. Approximately 10 mg of solubilized microsomal proteins was applied and the elution was completed within 2 h. Addition of N-nitrodiethylamine, an in vitro activator of GT activity, enhanced the GT activity toward 4-nitrophenol in the three fractions. This chromatographic analysis confirmed the absence of androsterone GT isoenzyme in LA Wistar rats, a mutant strain in terms of androsterone glucuronidation.

  13. 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.

  14. Chromatographic retention behaviour, modelling and separation optimisation of the quaternary ammonium salt isometamidium chloride and related compounds on a range of reversed-phase liquid chromatographic stationary phases.

    PubMed

    Schad, Gesa J; Euerby, Melvin R; Skellern, Graham G; Tettey, Justice N A

    2012-07-01

    This paper describes the reversed-phase liquid chromatographic behaviour of the trypanocidal quaternary ammonium salt isometamidium chloride and its related compounds on a range of liquid chromatographic phases possessing alkyl and phenyl ligands on the same inert silica. In a parallel study with various extended polar selectivity phases which possessed different hydrophobic/silanophilic (hydrogen bonding) activity ratios, the chromatographic retention/selectivities of the quaternary ammonium salts was shown to be due to a co-operative mechanism between hydrophobic and silanophilic interactions. The highly aromatic and planar isometamidium compounds were found to be substantially retained on stationary phases containing aromatic functionality via strong π-π interactions. The chemometric approach of principal component analysis was used to characterise the chromatographic behaviour of the isometamidium compounds on the differing phases and to help identify the dominant retention mechanism(s). Two-dimensional (temperature/gradient) retention modelling was employed to develop and optimise a rapid liquid chromatography method for the separation of the six quaternary ammonium salts within 2.5 min which would be suitable for bioanalysis using liquid chromatography-mass spectrometry. This is the first reported systematic study of the relationship between stationary phase chemistries and retention/selectivity for a group of quaternary ammonium salts.

  15. 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)

  16. Electroviscoelasticity of liquid/liquid interfaces: fractional-order model.

    PubMed

    Spasic, Aleksandar M; Lazarevic, Mihailo P

    2005-02-01

    A number of theories that describe the behavior of liquid-liquid interfaces have been developed and applied to various dispersed systems, e.g., Stokes, Reiner-Rivelin, Ericksen, Einstein, Smoluchowski, and Kinch. A new theory of electroviscoelasticity describes the behavior of electrified liquid-liquid interfaces in fine dispersed systems and is based on a new constitutive model of liquids. According to this model liquid-liquid droplet or droplet-film structure (collective of particles) is considered as a macroscopic system with internal structure determined by the way the molecules (ions) are tuned (structured) into the primary components of a cluster configuration. How the tuning/structuring occurs depends on the physical fields involved, both potential (elastic forces) and nonpotential (resistance forces). All these microelements of the primary structure can be considered as electromechanical oscillators assembled into groups, so that excitation by an external physical field may cause oscillations at the resonant/characteristic frequency of the system itself (coupling at the characteristic frequency). Up to now, three possible mathematical formalisms have been discussed related to the theory of electroviscoelasticity. The first is the tension tensor model, where the normal and tangential forces are considered, only in mathematical formalism, regardless of their origin (mechanical and/or electrical). The second is the Van der Pol derivative model, presented by linear and nonlinear differential equations. Finally, the third model presents an effort to generalize the previous Van der Pol equation: the ordinary time derivative and integral are now replaced with the corresponding fractional-order time derivative and integral of order p<1.

  17. Two-Dimensional Offline Chromatographic Fractionation for the Characterization of Humic-Like Substances in Atmospheric Aerosol Particles.

    PubMed

    Spranger, Tobias; van Pinxteren, Dominik; Herrmann, Hartmut

    2017-05-02

    Organic carbon in atmospheric particles comprises a large fraction of chromatographically unresolved compounds, often referred to as humic-like substances (HULIS), which influence particle properties and impact climate, human health, and ecosystems. To better understand its composition, a two-dimensional (2D) offline method combining size-exclusion (SEC) and reversed-phase liquid chromatography (RP-HPLC) using a new spiked gradient profile is presented. It separates HULIS into 55 fractions of different size and polarity, with estimated ranges of molecular weight and octanol/water partitioning coefficient (log P) from 160-900 g/mol and 0.2-3.3, respectively. The distribution of HULIS within the 2D size versus polarity space is illustrated with heat maps of ultraviolet absorption at 254 nm. It is found to strongly differ in a small example set of samples from a background site near Leipzig, Germany. In winter, the most intense signals were obtained for the largest molecules (>520 g/mol) with low polarity (log P ∼ 1.9), whereas in summer, smaller (225-330 g/mol) and more polar (log P ∼ 0.55) molecules dominate. The method reveals such differences in HULIS composition in a more detailed manner than previously possible and can therefore help to better elucidate the sources of HULIS in different seasons or at different sites. Analyzing Suwannee river fulvic acid as a common HULIS surrogate shows a similar polarity range, but the sizes are clearly larger than those of atmospheric HULIS.

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

    PubMed

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

    2014-07-21

    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.

  19. Fractionation of Gibberellins in plant extracts by reverse phase high performance liquid chromatography

    SciTech Connect

    Jones, M.G.; Metzger, J.D.; Zeevaart, J.A.D.

    1980-02-01

    In studies on endogenous plant gibberellins (GAs), reverse phase (Bondapak C/sub 18/) high performance liquid chromatography (HPLC) has proved to be a useful method for the fractionation of plant extracts. The behavior of 18 authentic GAs in such a chromatographic system is described. The main factors determining chromatographic behavior are the degree and the position of hydroxylation of the GA. As an illustration of the use of reverse phase HPLC, the endogeneous GAs of immature seeds of Pharbitis nil L., strain Violet, were reinvestigated. The presence of gibberellins A/sub 3/, A/sub 5/, A/sub 17/, A/sub 20/, and A/sub 29/ was confirmed by gas-liquid chromatography-mass spectrometry. In addition, two other GAs, A/sub 19/ and A/sub 44/, were also identified in extracts of this material.

  20. 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...

  1. High-performance liquid chromatographic determination of tilidine in pharmaceutical dosage forms.

    PubMed

    Zivanov-Stakić, D; Solomun, L J; Zivanović, L J

    1989-01-01

    A reversed-phase high performance liquid chromatographic method for the determination of tilidine in bulk drug and its liquid and solid dosage forms is described. The method uses reversed-phase column RP-8 with methanol -0.2% water solution of ammonium carbonate (75:25,v/v) as the mobile phase and UV detector. The time taken for separation is 6.17 min. The response is linear up to 3.6 mmol/l, with recovery levels ranging from 98.2 to 101.2%. The present method is rapid, simple and reproducible.

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

    PubMed

    Abidi, S L

    1988-08-05

    Using a reversed-phase high-performance liquid chromatographic (HPLC) technique, a mixture of antimycins A was separated into eight hitherto unreported subcomponents, A1a, A1b, A2a, A2b, A3a, A3b, A4a, and A4b. Although a base-line resolution of the known four major antimycins A1, 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 modifers, 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 interpreted 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.

  3. 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.

  4. Comparison of high-performance liquid chromatographic and thin-layer chromatographic methods for determination of aloin in herbal products containing Aloe vera.

    PubMed

    Ramírez Durón, Rosalba; Ceniceros Almaguer, Lucía; Cavazos Rocha, Norma Cecilia; Silva Flores, Perla Giovanna; De Torres, Noemí Waksman

    2008-01-01

    Aloe vera is a medicinal plant used worldwide to treat a variety of conditions and, as such, has important commercial value. Aloin is a principal component of aloe vera leaves and is used for quality control of products containing it. A semiquantitative thin-layer chromatographic (TLC) method for determining the concentration of aloin in aloe-based products was validated. The results were similar to those of a validated high-performance liquid chromatographic method; therefore, TLC, which is a simple, sensitive, specific, rapid, and cheap method, may be ideal for use in any laboratory for routine analysis of commercial products containing aloe vera.

  5. 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.

  6. An inverse gas chromatographic methodology for studying gas-liquid mass transfer.

    PubMed

    Paloglou, A; Martakidis, K; Gavril, D

    2017-01-13

    A novel methodology of reversed flow inverse gas chromatography (RF-IGC) is presented. It permits the simultaneous determination of mass transfer coefficients across the gas liquid interface as well as the respective solubility parameters and thermodynamic functions of dissolution of gases into liquids. The standard deviation of the experimentally determined parameters is estimated for first time, which combined with the successful comparison of the values of the present parameters with other literature ones ascertain the reliability of the methodology. Another novelty of the present work is that the chromatographic sampling of the physicochemical phenomena is done without performing the usual flow reversals procedure. Vinyl chloride monomer's (VCM) interaction with various composition liquid foods: orange juice, milk and olive oil was used as model system. The present transfer rates are controlled by the gas film at lower temperatures, but at higher temperatures the resistances in both films tend to become equal. The found liquid diffusivity values express the total mass transfer from the gas phase into the liquid's bulk and they decrease with rising temperature, as the solubilities of gases in liquids do. Solubility, expressed by Henry's law constant and the mean values of interfacial thickness are of the same order of magnitude to literature ones. From the thermodynamic point of view, VCM dissolution in all liquids is accompanied by significant heat release and it is a slightly non-spontaneous process, near equilibrium, while the entropy change values are negative. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Cucurbit(6)uril immobilized on silica: a novel high-performance liquid chromatographic stationary phase.

    PubMed

    Ma, Liyun; Liu, Simin; Wang, Qing; Yao, Lin; Xu, Li

    2015-04-01

    In the present study, one of the new generation of host molecules, cucurbit(6)uril (CB(6)), was immobilized onto silica (CB(6)/SiO2 ) by a sol-gel approach. CB(6)/SiO2 was characterized by NMR spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and elemental analysis. It was used as a high-performance liquid chromatographic stationary phase and its chromatographic performance was systematically investigated with different types of analytes as probes. The results revealed that the CB(6)/SiO2 stationary phase exhibited weak hydrophobic and strong hydrophilic properties. Hence, the variables for hydrophilic interaction liquid chromatography, including components and pH of the mobile phase, were further investigated to explore the retention mechanism of this CB(6)/SiO2 stationary phase. For less polar analytes, both hydrophobic and hydrophilic interactions could contribute to the retention, while for polar analytes, hydrophilic interaction may be predominant. Compared to the tetraethoxylsilane-coated SiO2 stationary phases, the CB(6)/SiO2 stationary phase exhibited a different retention behavior toward basic analytes with excellent stability. It is a novel promising hydrophilic interaction liquid chromatography stationary phase.

  8. Liquid chromatographic separation in metal-organic framework MIL-101: a molecular simulation study.

    PubMed

    Hu, Zhongqiao; Chen, Yifei; Jiang, Jianwen

    2013-02-05

    A molecular simulation study is reported to investigate liquid chromatographic separation in metal-organic framework MIL-101. Two mixtures are considered: three amino acids (Arg, Phe, and Trp) in aqueous solution and three xylene isomers (p-, m-, and o-xylene) dissolved in hexane. For the first mixture, the elution order is found to be Arg > Phe > Trp. The hydrophilic Arg has the strongest interaction with the polar mobile phase (water) and the weakest interaction with the stationary phase (MIL-101), and thus transports at the fastest velocity. Furthermore, Arg forms the largest number of hydrogen bonds with water and possesses the largest hydrophilic solvent-accessible surface area. For the second mixture, the elution order is p-xylene > m-xylene > o-xylene, consistent with available experimental observation. With the largest polarity as compared to p- and m-xylenes, o-xylene interacts the most strongly with the stationary phase and exhibits the slowest transport velocity. For both mixtures, the underlying separation mechanism is elucidated from detailed energetic and structural analysis. It is revealed that the separation can be attributed to the cooperative solute-solvent and solute-framework interactions. This simulation study, for the first time, provides molecular insight into liquid chromatographic separation in a MOF and suggests that MIL-101 might be an interesting material for the separation of industrially important liquid mixtures.

  9. High-performance liquid chromatographic determination of molluscicidal saponins from Phytolacca dodecandra (Phytolaccaceae).

    PubMed

    Slacanin, I; Marston, A; Hostettmann, K

    1988-09-02

    A high-performance liquid chromatographic method is described for the determination of oleanane saponins in Phytolacca dodecandra (Phytolaccaceae), a plant with potent molluscicidal properties. The molluscicidal monodesmosidic saponins of the berries were determined at 254 nm as their 4-bromophenacyl derivatives, whereas the non-derivatized bidesmosidic saponins, lacking a free carboxyl group, were determined at 206 nm. A comparison of different extraction procedures showed that with cold water predominantly monodesmosidic saponins were obtained, whereas hot water gave mainly bidesmosidic (non-molluscicidal) saponins.

  10. Quantitative high-performance liquid chromatographic determination of delta 4-3-ketosteroids in adrenocortical extracts.

    PubMed

    Ballerini, R; Chinol, M; Ghelardoni, M

    1980-05-30

    A high-performance liquid chromatographic method is described for the determination of seven steroids in adrenocortical extracts showing a delta 4-3-ketonic conjugated system. The seven steroids (cortisol, cortisone, 11-dehydrocorticosterone, corticosterone, 11-deoxycortisol, aldosterone and 11-deoxycorticosterone) were separated with a chloroform-methanol gradient on a 5-micron silica column and with a water-acetonitrile gradient on a 10-micron RP-8 column. Effluents were monitored by UV absorption at 242 nm. Quantitative analysis was performed by comparing peak areas, which are proportional to the amounts of the individual substances (external standard method). The method is rapid, sensitive, easy to perform and reproducible.

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

    PubMed

    Schulz, H; Albroscheit, G

    1988-06-17

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

  12. Column liquid chromatographic analysis of quinine in human plasma, saliva and urine.

    PubMed

    Babalola, C P; Bolaji, O O; Dixon, P A; Ogunbona, F A

    1993-06-23

    A new simple, selective and reproducible high-performance liquid chromatographic method for the determination of quinine in plasma, saliva and urine is described. The ion-pair method was carried out on a reversed-phase C18 column, using perchlorate ion as the counter ion and ultraviolet detection at 254 nm. Quinine was well resolved from its major metabolite, 3-hydroxyquinine, and the internal standard, primaquine. The limit of detection was 10 ng/ml and the recovery was greater than 90% from the three biological fluids.

  13. Validated liquid chromatographic-fluorescence method for the quantitation of gemifloxacin in human plasma.

    PubMed

    Al-Hadiya, Badraddin M H; Khady, Adnan A; Mostafa, Gamal A E

    2010-11-15

    A highly selective, sensitive and rapid high performance liquid chromatographic method has been developed and validated to quantify gemifloxacin in human plasma. The gemifloxacin and internal standard (ciprofloxacin) were extracted by ultrafiltration technique followed by injection into chromatographic system. Chromatographic separation was achieved on a reversed phase C(18) column with a mobile phase of acetonitrile:0.1% trifluoroacetic acid (20:80, v/v) using isocratic elution (at flow rate 1 mL min(-1)). The analytes were detected at 269 and 393 nm for excitation and emission, respectively. The assay exhibited a linear range of 25-5000 ng mL(-1) for gemifloxacin in human plasma. The lower limit of detection was 10 ng mL(-1). The method was statistically validated for linearity, accuracy, precision and selectivity following FDA guidelines. The intra- and inter-assay coefficients of variation did not exceed 7.6% deviation of the nominal concentration. The recovery of gemifloxacin from plasma was greater than 97.0%. Stability of gemifloxacin in plasma was excellent with no evidence of degradation during sample processing (auto-sampler) and at least 3 months storage in a freezer at -70 °C. This validation method is applied for clinical study of the gemifloxacin in human volunteers. Copyright © 2010 Elsevier B.V. All rights reserved.

  14. Development and validation of micellar liquid chromatographic methods for the determination of antibiotics in different matrixes.

    PubMed

    Rambla-Alegre, Maria; Esteve-Romero, Josep; Carda-Broch, Samuel

    2011-01-01

    Antibiotics are the most important bioactive and chemotherapeutic compounds to be produced by microbiological synthesis, and they have proved their worth in a variety of fields, such as medicinal chemistry, agriculture, and the food industry. Interest in antibiotics has grown in parallel with an increasingly high degree of productivity in the field of analytical applications. Therefore, it is necessary to develop chromatographic procedures capable of determining various drugs simultaneously in the shortest possible time. Micellar liquid chromatography (MLC) is an RP-HPLC technique that offers advantages over conventional HPLC as far as sample preparation, selectivity, and versatility are concerned. Its main advantage is that samples can be injected directly into the chromatographic system with no previous preparation step. This paper mainly focuses on the results of the authors' own recent research and reports the chromatographic conditions for determination of various antibiotics (penicillins, quinolones, and sulfonamides) in different matrixes (pharmaceuticals, biological fluids, and food). The work of other authors on MLC-based antibiotic determination has been included.

  15. 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.

  16. Reverse-phase high pressure liquid chromatographic analysis of harpagoside, scorodioside and verbascoside from Scrophularia scorodonia: quantitative determination of harpagoside.

    PubMed

    Díaz, A; Fernández, L; Ollivier, E; Martín, T; Villaescusa, L; Balansard, G

    1998-02-01

    A reversed-phase high performance liquid chromatographic method has been developed for the determination of the main compounds (harpagoside, scorodioside, and verbascoside) from different samples of Scrophularia scorodonia. The chromatographic method has been validated and applied for quantitative determination of harpagoside. The results show the highest levels of harpagoside in the leaf extract. The purity and identity of peaks were controlled by diode-array detection and comparison with standards.

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

    PubMed

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

    2014-08-08

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

  18. Gas-liquid chromatographic determination of sulfamethazine in swine and cattle tissues.

    PubMed

    Manuel, A J; Steller, W A

    1981-07-01

    A gas-liquid chromatographic (GLC) method is described for determining sulfonamide residues in animal tissues, with specificity for 7 sulfonamides. Residues are extracted from tissues with acetone-chloroform, fatty substances are removed, and the sulfonamide residue is methylated with diazomethane in acetone-ether to render it amenable to determination by gas-liquid chromatography on an all-glass column suitable for direct on-column injection and a Ni electron-capture detector. Quantitation is achieved by external standardization. The method has a validated limit of sensitivity of 0.10 ppm with the corresponding control values for all tissues being less than 0.01 ppm. Satisfactory recoveries have been obtained for sulfamethazine in swine and cattle tissues. Specificity for sulfamethazine in the presence of sulfathiazole, sulfaquinoxaline, sulfadimethoxine, sulfabromomethazine, sulfaethoxypyridazine, and sulfachloropyrazine is attained by resolution of the respective methyl derivatives on the GLC column.

  19. Ion-exchange liquid chromatographic determination of nitrate and nitrite in biological fluids.

    PubMed

    Lippsmeyer, B C; Tracy, M L; Möller, G

    1990-01-01

    A rapid, ion-exchange liquid chromatographic method for the determination of nitrate and nitrite in biological fluids is presented. Samples are deproteinated by ultrafiltration followed by removal of chloride using a silver form cation-exchange resin. Nitrate and nitrite are measured by ion-exchange liquid chromatography with conductivity detection. Recoveries from serum, ocular fluid, and water were determined for fortifications from 10 to 150 mg/L. Average recoveries ranged from 96 to 104% for nitrate and from 89 to 105% for nitrite. Pooled RSD values ranged between 1.5 and 1.9% for these analytes in all matrixes examined. The method of joint confidence hexagons was applied to the data to determine constant and relative bias of the method for each of the 3 matrixes in the study.

  20. 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.

  1. Simultaneous determination of tocopherols and tocotrienols in hazelnuts by a normal phase liquid chromatographic method.

    PubMed

    Amaral, Joana S; Casal, Susana; Torres, Duarte; Seabra, Rosa M; Oliveira, Beatriz P P

    2005-12-01

    A normal-phase high-performance liquid chromatography (NP-HPLC) method for the determination of tocopherols and tocotrienols in hazelnuts is reported. Three extraction procedures (with and without saponification) were assayed; the best results were obtained with a simple solid-liquid extraction procedure. Chromatographic separation was achieved using an Inertsil 5 SI column using isocratic elution with hexane/1,4-dioxane (95.5:4.5, v/v) at a flow rate of 0.7 mL/min. The effluent was monitored by a series arrangement of a diode-array followed by a fluorescence detector. All compounds were separated in a short period of time (17 min). The method proved to be rapid, sensitive, reproducible and accurate, allowing the simultaneous determination of all vitamin E homologues.

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

    PubMed

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

    1990-08-24

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

  3. Detection and quantification of affinity ligand leaching and specific antibody fragment concentration within chromatographic fractions using surface plasmon resonance.

    PubMed

    Thillaivinayagalingam, Pranavan; Newcombe, Anthony R; O'Donovan, Kieran; Francis, Richard; Keshavarz-Moore, Eli

    2007-12-01

    Rapid analyses of chromatographic steps within a biopharmaceutical manufacturing process are often desirable to evaluate column performance, provide mass balance data and to permit accurate calculations of yields and recoveries. Using SPR (surface plasmon resonance) biosensor (Biacore) technology, we have developed a sandwich immunoassay to quantify polyclonal anti-digoxin Fab fragments used for the production of the FDA (Food and Drug Administration)-approved biotherapeutic DigiFab. The results show that specific Fab may be quantified in all affinity process streams and accurate yield and mass balance data calculated. Control experiments using sheep Fab and Fc indicate that the assay is specific to DigiFab. The quantification of potential leached ligand within chromatographic fractions may also be technically challenging, particularly when low-molecular-mass ligands are covalently coupled with an affinity absorbent. Typical methods to assess ligand leakage such as DDMA (digoxin-dicarboxymethoxylamine; digoxin analogue) often involve the use of labelled ligands and relatively complex and labour-intensive analytical techniques. Using the same analytical methodologies, an assay to detect leached or eluted ligand off the column was developed. The results indicate minimal levels of leached ligand in all chromatographic fractions, with total levels of leached DDMA calculated to be 1.52 microg. This is less than 0.01% of the total amount of DDMA coupled with the laboratory-scale affinity column. The SPR methods described in the present study may be applicable for the rapid in-process analysis of specific polyclonal Fab fragments (within a polyclonal mixture) and to rapidly assess leakage of small molecule ligands covalently attached to chromatographic supports.

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

    PubMed

    Huan, Tao; Li, Liang

    2015-07-21

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

  5. Liquid chromatographic determination of tocopherols and tocotrienols in vegetable oils, formulated preparations, and biscuits.

    PubMed

    Bonvehi, J S; Coll, F V; Rius, I A

    2000-01-01

    A precise and selective liquid chromatographic procedure for determining tocopherol and tocotrienol isomers in vegetable oils, formulated preparations, and biscuits was developed and validated. The proposed method quantitates vitamin E in better conditions of recoverability and reproducibility than the standard saponification procedure. Tocopherols and tocotrienols were extracted in hexane from vegetable oils, passed through a silica Sep-pak, chromatographed on a mu-Bondapak C18 column with a mobile phase of methanol-water (95 + 5, v/v), identified at 292 nm, and detected with fluorescence procedure (excitation 296 nm, and emission 330 nm). The correlation coefficient on the calibration curve was 0.9995 over the range of 0.1 to 100 microg/mL. Overall recovery of vitamin E isomers was 93%; coefficients of variation for intra- and interday precision, < 2.25%. The results obtained from extraction methods 1 (with saponification) and 2 (without saponification) were compared by ANOVA test. Significant differences appeared between vitamin E isomers (p < or = 0.05).

  6. [Solid phase extraction and high performance liquid chromatographic determination of enalapril in human plasma].

    PubMed

    Tan, L; Yuan, Y S; Zhang, X; Zhao, F L

    1997-11-01

    A reversed phase high performance liquid chromatographic method utilizing solid phase extraction has been described for the determination of enalapril in human plasma. The C18 sorbent cartridges were conditioned and plasma samples were applied, washed with 20 mmol.L-1 HCl (2 x 0.5 ml) and petroleum ether (boiling range 60-90 degrees C) subsequently; and eluted with methanol (3 x 0.5 ml). The eluent was evaporated to dryness, reconstituted in 100 microliters mobile phase and injected. Chromatographic separation was achieved on a Spherisorb C8 column (200 mm x 4.6 mm, 5 microns), with ethanol--water--10% H3PO4--triethylamine (30:70:1.5:0.1) at a flow rate of 1.0 ml.min-1. UV detection was set at 215 nm. The calibration ranges were 2.5-150 ng.ml-1 with regression coefficient of 0.997 and detection limit of 1.5 ng.ml-1. The within-day RSD and between-day RSD were < 8.73%, the recovery of method > 91.6%. This method was applied to the pharmacokinetic analysis of enalapril in 8 human volunteers.

  7. High-efficiency high performance liquid chromatographic analysis of red wine anthocyanins.

    PubMed

    de Villiers, André; Cabooter, Deirdre; Lynen, Frédéric; Desmet, Gert; Sandra, Pat

    2011-07-22

    The analysis of anthocyanins in natural products is of significant relevance in recent times due to the recognised health benefits associated with their consumption. In red grapes and wines in particular, anthocyanins are known to contribute important properties to the sensory (colour and taste), anti-oxidant- and ageing characteristics. However, the detailed investigation of the alteration of these compounds during wine ageing is hampered by the challenges associated with the separation of grape-derived anthocyanins and their derived products. High performance liquid chromatography (HPLC) is primarily used for this purpose, often in combination with mass spectrometric (MS) detection, although conventional HPLC methods provide incomplete resolution. We have previously demonstrated how on-column inter-conversion reactions are responsible for poor chromatographic efficiency in the HPLC analysis of anthocyanins, and how an increase in temperature and decrease in particle size may improve the chromatographic performance. In the current contribution an experimental configuration for the high efficiency analysis of anthocyanins is derived using the kinetic plot method (KPM). Further, it is shown how analysis under optimal conditions, in combination with MS detection, delivers much improved separation and identification of red wine anthocyanins and their derived products. This improved analytical performance holds promise for the in-depth investigation of these influential compounds in wine during ageing. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Stability Indicating Liquid Chromatographic Method for the Simultaneous Determination of Rosuvastatin and Ezetimibe in Pharmaceutical Formulations

    PubMed Central

    Mukthinuthalapati, Mathrusri Annapurna; Bukkapatnam, Venkatesh; Bandaru, Sai Pavan Kumar

    2014-01-01

    Purpose: A simple stability indicating reverse phase liquid chromatographic method was developed for the simultaneous determination of rosuvastatin and ezetimibe in pharmaceutical formulations. Methods: Best chromatographic response was achieved with C18 column (250 X 4.6 mm, 5µm) with photo diode array (PDA) detector. The mobile phase was composed of a mixture of sodium acetate buffer (pH 4.0) and acetonitrile (30:70, %v/v) with a flow rate of 1.2 mL/min. (UV detection at 254 nm). Rosuvastatin and ezetimibe were subjected to stress conditions of degradation and the method was validated as per ICH guidelines. Results: The method shows linearity over a concentration range of 0.5-250 µg/ml for both rosuvastatin (r2 = 0.9993) and ezetimibe (r2 = 0.9996). Both the drugs are highly sensitive towards alkaline conditions in comparison to other stress conditions. Conclusion: The proposed method can be successfully applied to perform long-term and accelerated stability studies for the simultaneous determination of rosuvastatin and ezetimibe in pharmaceutical formulations. PMID:25436199

  9. 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.

  10. Liquid Chromatographic Separation and Thermodynamic Investigation of Mirabegron Enantiomers on a Chiralpak AY-H Column.

    PubMed

    Zhou, Fan; Zhou, Yuxia; Zou, Qiaogen; Sun, Lili; Wei, Ping

    2015-09-01

    Liquid chromatographic separation of mirabegron enantiomers on Chiralpak AY-H, a column coated with amylose tris-(5-chloro-2-methylphenylcarbamate) as a chiral stationary phase, was studied under normal phase conditions. The influence of ethanol content (30-45%) and column temperature (20-40°C) on retention, resolution and separation were evaluated. Apparent thermodynamic parameters deduced from Van't Hoff plots were used to understand chiral separation mechanisms, and the chiral separation was enthalpy driven. The optimized chromatographic conditions were using a mixture solution of n-hexane, ethanol and diethyl amine (55 : 45 : 0.1, v/v/v) as a mobile phase at a flow rate of 1.0 mL/min. The column temperature and UV detector were set at 35°C and 254 nm, respectively. The method was validated to be simple, accuracy, sensitive and robust according to the ICH guidelines, and it was suitable for the routine quality control of mirabegron enantiomers for pharmaceutical industries.

  11. Kinetic optimisation of the reversed phase liquid chromatographic separation of rooibos tea (Aspalathus linearis) phenolics on conventional high performance liquid chromatographic instrumentation.

    PubMed

    Beelders, Theresa; Sigge, Gunnar O; Joubert, Elizabeth; de Beer, Dalene; de Villiers, André

    2012-01-06

    Rooibos tea, produced from the endemic South African shrub Aspalathus linearis, has various health-promoting benefits which are attributed to its phenolic composition. Generating reliable, quantitative data on these phenolic constituents is the first step towards documenting the protective effects associated with rooibos tea consumption. Reversed phase liquid chromatographic (RP-LC) methods currently employed in the quantitative analysis of rooibos are, however, hampered by limited resolution and/or excessive analysis times. In order to overcome these limitations, a systematic approach towards optimising the RP-LC separation of the 15 principal rooibos tea phenolics on a 1.8 μm phase using conventional HPLC instrumentation was adopted. Kinetic plots were used to obtain the optimal configuration for the separation of the target analytes within reasonable analysis times. Simultaneous optimisation of temperature and gradient conditions provided complete separation of these rooibos phenolics on a 1.8 μm C18 phase within 37 min. The optimised HPLC-DAD method was validated and successfully applied in the quantitative analysis of aqueous infusions of unfermented and fermented rooibos. Major phenolic constituents of fermented rooibos were found to be a phenylpropanoid phenylpyruvic acid glucoside (PPAG), the dihydrochalcone C-glycoside aspalathin, the flavones isoorientin and orientin, and a flavonol O-diglycoside tentatively identified as quercetin-3-O-robinobioside. Content values for PPAG, ferulic acid and quercetin-3-O-robinobioside in rooibos are reported here for the first time. Mass spectrometric (MS) and tandem MS detection were used to tentatively identify 13 additional phenolic compounds in rooibos infusions, including a new luteolin-6-C-pentoside-8-C-hexoside and a novel C-8-hexosyl derivative of aspalathin reported here for the first time.

  12. Rocket-powered high-performance liquid chromatographic analysis of plant ascorbate and glutathione.

    PubMed

    Davey, M W; Dekempeneer, E; Keulemans, J

    2003-05-01

    We describe a robust procedure for the extraction and high-performance liquid chromatographic analysis of L-ascorbate (vitamin C), glutathione (gamma-glutamyl cysteinylglycine), and their respective oxidized forms from various plant tissues. Parameters such as the choice of extraction buffer, tissue disruption technique, sample stability, and separation conditions have all been optimized. In particular we found that the inclusion of the reducing agent dithiothreitol as a "stabilizer" in extracts with high phenolic content actually promoted oxidation of these antioxidants. Further, by using commercially available short "Rocket" HPLC columns in combination with high mobile-phase flow rates, analysis times were reduced to only 6min, making the method suitable for the high-resolution screening of large numbers of samples.

  13. High-performance liquid chromatographic analysis of anthraquinone compounds in the Laurera benguelensis

    NASA Astrophysics Data System (ADS)

    Manojlović, N.; Marković, Z.; Gritsanapan, W.; Boonpragob, K.

    2009-09-01

    A high-performance liquid chromatographic (HPLC) method has been developed for the characterization of anthraquinone metabolites in extracts of the lichen Laurera benguelensis. With this method four anthraquinone derivatives 1,8-dihydroxy-3-methoxy-6-methylanthraquinone, 1,8-dihydroxy-3-formyl-6-methoxyanthraquinone, 1,8-dihydroxy-3-hydroxymethyl-6-methoxy-anthraquinone and 1,3,8-trihyroxy-6-methylanthraquinone can be analyzed. Components of lichen were detected by characteristic ultraviolet spectra and relative retention times. This is first report of phytochemical analysis of L. benguelensis. Importance of this research is in recognizing some new source (lichen and its extracts) as a natural emplacement of antioxidants because oxidation with free radicals or autooxidation is big problem for preservation of food products.

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

    PubMed

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

    1995-01-01

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

  15. A minicomputer-automated array spectrometer for liquid-chromatographic detection of metabolites.

    PubMed

    Dessy, R E; Reynolds, W D; Nunn, W G; Titus, C A; Moler, G F

    1976-09-01

    A third-generation multiwavelength array spectrometer was developed as a detector for the high-resolution liquid-chromatographic characterization of metabolites. Components include a PDP-8/e minicomputer, matched pair of linear photodiode arrays, holographically-ruled gratings, fiber optics, flow cells, and high intensity xenon light source. The wavelength range is 256 nm differential with 1-nm resolution and can be adjusted from 200 to 800 nm. The system is capable of storing 20 spectra per second (200-456 nm) in a dual-beam mode. Special features include minicomputer-driven signal enhancement via integration as a function of signal strength. The display output includes presentation of the total absorption chromatogram vs. elution time in both real and post-run time as well as selectable single absorption band vs. elution time (post-run time). Application of this dedicated system is illustrated by the separation and charcterization of the metabolites of a carcinogen, 4-ethylsulfonyl-1 napthalenesulfonamide.

  16. Liquid chromatographic determination of atropine in nerve gas antidotes and other dosage forms.

    PubMed

    Lehr, G J; Yuen, S M; Lawrence, G D

    1995-01-01

    A simple and specific liquid chromatographic method was developed for the determination of atropine in nerve gas antidotes and several other dosage forms. The method is also used simultaneously to quantitate phenol, an antimicrobial agent present in nerve gas antidotes, and to monitor the level of tropic acid, a principal degradation product of atropine. The system uses a Spherisorb CN column and a mobile phase of acetonitrile-0.05M sodium phosphate monobasic (10 + 90), pH 4.0. The detection wavelength is 220 nm. The method was validated by testing for accuracy, linearity, reproducibility and precision. In addition, the proposed method was applied to 8 commercial preparations of atropine, including injectables, ophthalmic solutions, and ointments, and was found to be satisfactory and free from interferences from preservatives, such as benzyl alcohol, methylparaben, benzalkonium chloride and chlorobutanol, that are present in these formulations.

  17. Chromatographic separation of vanadium, tungsten and molybdenum with a liquid anion-exchanger.

    PubMed

    Fritz, J S; Topping, J J

    1971-09-01

    In acidic solution only molybdenum(VI), tungsten(VI), vanadium(V), niobium(V) and tantalum(V) form stable, anionic complexes with dilute hydrogen peroxide. This fact has been used in developing an analytical method of separating molybdenum(VI), tungsten(VI) and vanadium(V) from other metal ions and from each other. Preliminary investigations using reversed-phase paper chromatography and solvent extraction led to a reversed-phase column Chromatographic separation technique. These metal-peroxy anions are retained by a column containing a liquid anion-exchanger (General Mills Aliquat 336) in a solid support. Then molybdenum(VI), tungsten(VI) and vanadium(V) are selectively eluted with aqueous solutions containing dilute hydrogen peroxide and varying concentrations of sulphuric acid.

  18. High-performance liquid chromatographic determination of vertilmicin in rat plasma using sensitive fluorometric derivatization.

    PubMed

    Liu, Zhen; Sha, Yunfei; Huang, Taomin; Yang, Bei; Duan, Geng-Li

    2005-12-15

    A sensitive and reliable high-performance liquid chromatographic method was developed for the determination of vertilmicin in rat plasma. Derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) followed by C(18) reversed-phase chromatography allowed the fluorimetric detection of vertilmicin. Optimal conditions for the derivatization of vertilmicin are described. The limit of quantification was 0.02 mg/L. The pharmacokinetics of vertilmicin was studied in 24 rats following intramuscular injection (i.m.) of different doses (4, 8, 16, 32 mg/kg of body weight). The pharmacokinetic parameter values were estimated by use of 3P97 program. In this study, we assessed the dose proportionality of vertilmicin after single intramuscular injection doses and obtained new information on the pharmacokinetics of the compound.

  19. Advances in high-throughput and high-efficiency chiral liquid chromatographic separations.

    PubMed

    Patel, Darshan C; Wahab, M Farooq; Armstrong, Daniel W; Breitbach, Zachary S

    2016-10-07

    The need for improved liquid chromatographic chiral separations has led to the advancement of chiral screening techniques as well as the development of new, high efficiency chiral separation methods and stationary phases. This review covers these advancements, which primarily occurred over the last 15 years. High throughput techniques include multi-column screening units, multiple injection sequences, and fast gradient SFC screening. New separation methods and column technologies that aim at high efficiency chiral separations include the use of achiral UHPLC (i.e. sub-2μm) columns for separating derivatized chiral analytes or using chiral additives in the run buffer, UHPLC chiral stationary phases, and superficially porous particle based chiral stationary phases. Finally, the enhancement of chiral separations through these new technologies requires that certain instrumental considerations be made. Future directions in continuing to improve chiral separations are also discussed.

  20. Liquid chromatographic determination of amprolium in chicken tissues, using post-column reaction and fluorometric detection.

    PubMed

    Nagata, T; Saeki, M

    1986-01-01

    A method is presented for determination of amprolium residues in chicken muscles by a liquid chromatographic post-column reaction system. The drug is extracted from muscles with methanol, and the extract is concentrated to 3-4 mL. This aqueous solution is rinsed with n-hexane and cleaned up by alumina column chromatography. The drug is separated from the interferences on a LiChrosorb RP-8 column, reacted with ferricyanide in alkaline solution, and quantitated by fluorometric detection at 367 nm (excitation) and 470 nm (emission). Recoveries of amprolium added to chicken muscles at levels of 0.1 and 0.2 ppm were 74.9 and 80.9%, respectively. The detection limit was 1 ng for amprolium standard and 0.01 ppm in chicken muscles.

  1. Liquid chromatographic determination of amprolium in poultry feed and premixes using postcolumn chemistry with fluorometric detection.

    PubMed

    Vanderslice, J T; Huang, M H

    1987-01-01

    Two extraction and liquid chromatographic procedures are presented which separate amprolium from compounds in poultry feed or premixes that could interfere with its fluorometric determination. The procedures are based on earlier work on the determination of thiamine in food samples. Amprolium is extracted from feed with a hexane-aqueous sulfosalicylic acid mix, separated on a C18 column, and detected fluorometrically after postcolumn derivatization. For premixes, water extraction is used. Values for the amprolium content of poultry feed obtained with these procedures are in good agreement with those obtained with AOAC official methods. It is suggested that these methods with suitable modifications may be of use for routine analysis of amprolium in feeds. The overall methods are rapid and appear to give reasonable results.

  2. 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%.

  3. Liquid chromatographic method for the determination of enantiomeric composition of amphetamine and methamphetamine in hair samples.

    PubMed

    Phinney, Karen W; Sander, Lane C

    2004-01-01

    Interest in hair analysis as an alternative or complementary approach to urinalysis for drug abuse detection has grown in recent years. Hair analysis can be particularly advantageous for drugs such as amphetamine and methamphetamine that are rapidly excreted. Confirmation of abuse of these stimulants is complicated by the fact that some forms are found in legitimate medications. Examination of the enantiomeric composition of amphetamine and methamphetamine in hair samples can provide valuable assistance in interpreting drug testing results. In this work, we developed a liquid chromatographic method for the separation of amphetamine and methamphetamine enantiomers isolated from human hair samples. The drug enantiomers were separated on a chiral stationary phase after derivatization with an achiral fluorescent agent. The methodology was evaluated with a Standard Reference Material that contained several drugs of abuse including amphetamine and methamphetamine.

  4. High-performance liquid chromatographic method for the determination of spectinomycin in turkey plasma.

    PubMed

    Burton, S D; Hutchins, J E; Fredericksen, T L; Ricks, C; Tyczkowski, J K

    1991-11-15

    A selective high-performance liquid chromatographic (HPLC) method with ultraviolet-visible (UV-VIS) detection was developed to measure therapeutic concentrations of spectinomycin in turkey plasma. Treatment of plasma samples with 3% trifluoroacetic acid in acetonitrile facilitated spectinomycin extraction and protein precipitation. After centrifugation, the stable derivatization reagent, 2,4-dinitrophenyl-hydrazine, was added to an aliquot of the supernatant, and the mixture was incubated for 30 min at 70 degrees C. Excess reagent was quenched with acetone and additional heating. The resulting derivative, a proposed spectinomycin-hydrazone, was separated from other compounds by reversed-phase HPLC during a short gradient run. The absorbance of the effluent was monitored spectrophotometrically with the UV-VIS detector set at 205 nm. The detector response was linear through the range of interest, 2-100 micrograms/ml.

  5. A new procedure for the specific high-performance liquid chromatographic determination of hydroxyproline.

    PubMed

    Biondi, P A; Chiesa, L M; Storelli, M R; Renon, P

    1997-11-01

    A procedure suitable for a selective high-performance liquid chromatographic (HPLC) analysis of the imino acid hydroxyproline in the presence of a large excess of amino acids is proposed. To deaminate the amino acids, the well-known reaction with nitrous acid is exploited. The N-nitroso derivatives of imino acids obtained are extracted in ethyl acetate, denitrosated by hydrobromic acid, and treated with dabsyl-chloride. The final HPLC separations are carried out on a reversed-phase column in a rapid isocratic run. The use of the cis isomer of hydroxyproline as an internal standard allows good reproducibility. As an application of the described method, the hydroxyproline content in samples containing collagen and an excess of bovine serum albumine (up to 20:1) is determined.

  6. Liquid chromatographic determination of leuco base in FD&C Blue No. 1.

    PubMed

    Scher, A L; Murray, H D

    1986-01-01

    Methods are described for the determination of leuco base in FD&C Blue No. 1 by reverse phase liquid chromatography and for the preparation and standardization of leuco base stock solution. The stock solution is prepared by reductive titration of the color with TiCl3. Solutions of the color and of leuco base are chromatographed by isocratic elution, which is followed by a wash and equilibration that can be omitted for screening. Peak area and height calibrations were linear. At the specification level, the 99% prediction limits were 5.00 +/- 0.14% (area) and 5.00 +/- 0.37% (height). Limits of determination were 0.29% (area) and 0.73% (height) at the 99.5% confidence level. Recoveries were 97-101% for leuco base added to FD&C Blue No. 1 at levels of 1-6%.

  7. Correlation of the "EMIT" antiepileptic drug assay with a gas liquid chromatographic method.

    PubMed

    Legaz, M; Raisys, V A

    1976-02-01

    Many methodologies have been developed for determining anticonvulsant drug levels in human serum. Unfortunately, most procedures are either time consuming or subject to a variety of interferring substances. The "Enzyme Multiplied Immunoassay Technique" (EMIT) system has been evaluated for its speed, sensitivity, accuracy, and precision. When compared with a gas-liquid chromatographic procedure, the EMIT assay appeared to yield results which were statistically comparable for the drugs diphenylhydantoin, phenobarbital, and primidone. The EMIT assay also demonstrated no significant interference when challenged with extraordinarily high levels of potentially cross reacting drugs. Results obtained with the EMIT assay correlated well with GLC data and rank it as an attractive alternative to many of the existing procedures now being used.

  8. Rapid liquid chromatographic method to distinguish wild salmon from aquacultured salmon fed synthetic astaxanthin.

    PubMed

    Turujman, S A; Wamer, W G; Wei, R R; Albert, R H

    1997-01-01

    Analytical methods are needed to determine the presence of color additives in fish. We report a liquid chromatographic (LC) method developed to identify the synthetic form of the color additive astaxanthin in salmon, based on differences in the relative ratios of the configurational isomers of astaxanthin. The distributions of configurational isomers of astaxanthin in the flesh of wild Atlantic and wild Pacific salmon are similar, but significantly different from that in aquacultured salmon. Astaxanthin is extracted from the flesh of salmon, passed through a silica gel Sep-Pak cartridge, and analyzed directly by LC on a Pirkle covalent L-leucine column. No derivatization of the astaxanthin is required-an important advantage of our approach, which is a modification of our previously described method. This method can be used to distinguish between aquacultured and wild salmon. The method has general applicability and can also be used to identify astaxanthins derived from other sources such as Phaffia yeast and Haematococcus pluvialis algae.

  9. Optimizing ultraperformance liquid chromatographic analysis of 10 diterpenoid compounds in Salvia miltiorrhiza using central composite design.

    PubMed

    Li, Peng; Xu, Gang; Li, Shao-Ping; Wang, Yi-Tao; Fan, Tai-Ping; Zhao, Qin-Shi; Zhang, Qing-Wen

    2008-02-27

    A rapid, sensitive, reproducible, and accurate ultraperformance liquid chromatographic (UPLC) method was developed for the simultaneous determination of 10 diterpenoid compounds (tanshinone I, tanshinone IIA, cryptotanshinone, dihydrotanshinone I, 1,2-dihydrotanshinquinone, methylenetanshinquinone, miltirone, 5,6-dehydrosugiol, sugiol, and przewalskin) in Salvia miltiorrhiza for the first time. Central composite design was applied as a powerful tool to optimize the most dominant parameters that influence the resolution of UPLC, that is, gradient, flow rate, and column temperature. Under optimum conditions, all peaks except 1,2-dihydrotanshinquinone and methylenetanshinquinone could be baseline separated within 8 min. Furthermore, the contents of these compounds in S. miltiorrhiza samples collected from different provinces of China have also been compared. The results showed that UPLC is one of the most efficient methods for the analysis of diterpenoid compounds in S. miltiorrhiza and that it is a potential method for quality control of this valuable traditional Chinese medicine.

  10. Spectrophotometric and high performance liquid chromatographic determination of cetirizine dihydrochloride in pharmaceutical tablets.

    PubMed

    el Walily, A F; Korany, M A; el Gindy, A; Bedair, M F

    1998-07-01

    Derivative spectrophotometric, colorimetric and high performance liquid chromatographic methods, for the determination of the antihistaminic cetirizine dihydrochloride in tablet form were described. Spectrophotometrically, cetirizine was determined by the measurement of its first (1D) and second (2D) derivative amplitudes at 239 (peak) and 243-233 nm (peak-to-trough), respectively. The aqueous solutions obeyed Beer's law in the concentration ranges of 1.2-10.0 and 0.8-10.0 micrograms ml-1 for 1D and 2D measurements, respectively. The colorimetric procedure was based on measuring the absorbency of the coloured chromogen resulted from the reaction between cetirizine sodium salt in polar solvent (DMF) and chloranil at 556 nm. The relation with concentrations was linear over 120-250 micrograms ml-1. Optimization of the reaction conditions was studied. At the same time, investigation of the complex formed was made with respect to its composition and the associated constant. A simple liquid chromatographic assay has been developed for the determination of cetirizine dihydrochloride in the presence of one of its synthesis precursor (hydroxyzine hydrochloride). A Bondapak-C18 column was used with a mobile phase consisting of acetonitrile/0.01 M ammonium dihydrogen phosphate (32:68, v/v) containing 0.1% w/v tetrabutyl ammonium hydrogen sulphate adjusted to pH 3 with phosphoric acid at a flow rate of 2 ml min-1. With salicylic acid as internal standard, quantitation was achieved with UV detection at 230 nm based on the peak height ratios. Beer's law was obeyed in a concentration range of 3-35 micrograms ml-1 and the regression line equation was derived with a correlation coefficient of 0.9999. The validity of the methods was further confirmed using the standard addition method. The proposed procedures were successfully applied to the determination of cetirizine in bulk and tablet form, with high percentage of recovery, good accuracy and precision.

  11. High-performance liquid chromatographic determination of cotinine in urine in isocratic mode.

    PubMed

    Ceppa, F; El Jahiri, Y; Mayaudon, H; Dupuy, O; Burnat, P

    2000-09-15

    A simple procedure for the determination of cotinine, major metabolite of nicotine in urine, is described. The assay involved a liquid-liquid extraction with dichloromethane in alkaline environment. The extract was dried at ambient temperature under a gentle stream of nitrogen. The residue was dissolved in 300 microl of mobile phase and 30 microl aliquot was injected via an automatic sampler into the liquid chromatograph and eluted with the mobile phase (10-9%, v/v methanol and acetonitrile, respectively in potassium dihydrogenphosphate buffer adjusted to pH 3.4) at a flow rate of 1 ml/min on a C8 Symmetry cartridge column (5 microm, 150 mm x 3.9 mm, Waters) at 25 degrees C. The eluate was detected at 260 nm. Internal standard was 2-phenylimidazole. Sensitive and specific, this technique was performed to test urine of diabetic patients (smokers and non-smokers) admitted in an endocrinology service. Urinary cotinine seems to be a better marker of smoking status than thiocyanates.

  12. High-performance liquid chromatographic assay for mitoxantrone in plasma using electrochemical detection.

    PubMed

    Choi, K E; Sinkule, J A; Han, D S; McGrath, S C; Daly, K M; Larson, R A

    1987-09-04

    A sensitive and specific high-performance liquid chromatographic (HPLC) assay was developed for the quantitation of mitoxantrone in plasma using electrochemical detection. Bisantrene was chosen as the internal standard. A reversed-phase, 10-microns muBondapak C18 analytical column (30 cm X 3.9 mm) with an isocratic mobile phase of 28% acetonitrile in 80 mM sodium formate buffer (pH 3.0) was used. The eluent was monitored by both electrochemical detection at an applied potential of +0.75 V vs. Ag/AgCl and visible absorbance at 660 nm. Only electrochemical detection was able to quantitate the internal standard and provided ten times higher sensitivity than visible absorbance for mitoxantrone with a detection limit as low as 0.1 ng/ml. Calibration curves in the range 0.1-1000 ng/ml showed good linearity (r = 0.998) and precision (coefficient of variation less than 10%). This HPLC method utilized a reproducible and inexpensive liquid-liquid extraction procedure. Using methylene chloride, the extraction efficacy of mitoxantrone from plasma was 85.3% with a coefficient of variation less than 2.1%. This new assay was then applied to measure mitoxantrone concentrations in plasma obtained from two leukemic patients receiving 12 mg/m2 mitoxantrone as a 1-h infusion.

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

    SciTech Connect

    Benz, Nancy

    1994-01-01

    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.

  14. Study of the metabolism of pyrazinamide using a high-performance liquid chromatographic analysis of urine samples.

    PubMed

    Yamamoto, T; Moriwaki, Y; Takahashi, S; Hada, T; Higashino, K

    1987-02-01

    A reversed-phase high-performance liquid chromatographic method was developed for the simultaneous determination of pyrazinamide and its metabolites in urine. Study of the metabolism of pyrazinamide by this method demonstrated that 5-hydroxypyrazinamide excretion was compatible with pyrazinoic acid excretion and allopurinol decreased in vivo conversion of pyrazinamide to 5-hydroxypyrazinamide and blocked that of pyrazinoic acid to 5-hydroxypyrazinoic acid.

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

    USDA-ARS?s Scientific Manuscript database

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

  16. Protein microarrays using liquid phase fractionation of cell lysates.

    PubMed

    Yan, Fang; Sreekumar, Arun; Laxman, Bharathi; Chinnaiyan, Arul M; Lubman, David M; Barder, Timothy J

    2003-07-01

    We describe an approach in which protein microarrays are produced using a two-dimensional (2-D) liquid phase fractionation of cell lysates. The method involves a pI-based fractionation using chromatofocusing in the first dimension followed by nonporous reversed-phase high-performance liquid chromatography (HPLC) of each pI fraction in the second dimension. This allows fractionation of cellular proteins in the liquid phase that could then be arrayed on nitrocellulose slides and used to study humoral response in cancer. Protein microarrays have been used to identify potential serum biomarkers for prostate cancer. It is shown that specific fractions are immunoreactive against prostate cancer serum but not against serum from healthy individuals. These proteins could serve as sero-diagnostic markers for prostate cancer. Importantly, this method allows for use of post-translationally modified proteins as baits for detection of humoral response. Proteins eliciting an immune response are identified using the molecular mass and peptide sequence data obtained using mass spectrometric analysis of the liquid fractions. The fractionation of proteins in the liquid phase make this method amenable to automation.

  17. 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

    2016-06-05

    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. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. 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.

  19. 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.

  20. Symmetry fractionalization of visons in Z2 spin liquids

    NASA Astrophysics Data System (ADS)

    Qi, Yang; Cheng, Meng; Fang, Chen

    In this work we study symmetry fractionalization of vison excitations in topological Z2 spin liquids. We show that in the presence of the full SO (3) spin-rotational symmetry and if there is an odd number of spin-1/2 per unit cell, the symmetry fractionalization of visons is completely fixed. On the other hand, visons can have different classes of symmetry fractionalization if the spin-rotational symmetry is reduced. As a concrete example, we show that visons in the Balents-Fisher-Girvin Z2 spin liquid have crystal symmetry fractionalization classes which are not allowed in SO (3) symmetric spin liquids, due to the reduced spin-rotational symmetry.

  1. 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.

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

    PubMed

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

    2012-07-01

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

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

    PubMed

    Soares, Belinda; Passos, Helena; Freire, Carmen S R; Coutinho, João A P; Silvestre, Armando J D; Freire, Mara G

    2016-09-07

    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.

  4. 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

  5. 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. ICS © 2013 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  6. Column-switching high-performance liquid chromatographic determination of vancomycin in serum.

    PubMed

    Demotes-Mainard, F; Labat, L; Vinçon, G; Bannwarth, B

    1994-06-01

    Concentrations of vancomycin in serum were measured by an automatic high-performance liquid chromatographic (HPLC) micromethod. Vancomycin is a glycopeptide antibiotic with broad application in the therapy of gram-positive infections. As this drug is potentially nephro- and ototoxic, a method to maximize its therapeutic benefit while minimizing the risk of toxicity is desirable. This fully automated HPLC method did not involve a sample pretreatment step. The configuration of the apparatus permitted a solid phase extraction of the serum sample on two precolumns filled with a reversed-phase material, followed by a chromatographic separation of the sample constituents on an analytical column. The reversed phase analytical column (muBondapak C18) was flushed with a mobile phase of water-acetonitrile-triethylamine, 870: 130: 4 (vol/vol/vol); the pH was adjusted to 3.0 with orthophosphoric acid. Precision was expressed as the coefficient of variation (CV), which was always < or = 4.13% for intra- and inter-assays (n = 10) in the range 2-50 micrograms/ml. We compared this specific HPLC determination to an enzyme-multiplied immunoassay (EMIT). Fifty clinical samples obtained from patients under vancomycin therapy were assayed by each method and results compared using a linear regression analysis. There was a significant correlation between results from HPLC and EMIT: EMIT = 0.51 + 1 x HPLC (r = 0.963; p < 0.0001). The rapidity and specificity of this HPLC micromethod make it suitable for use in the monitoring of serum levels of vancomycin and for use in pharmacokinetic studies of this antibiotic.

  7. 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.

  8. Evaluation and application of liquid chromatographic columns coated with 'intelligent' ligands: (I) acylcarnitine column.

    PubMed

    Kamimori, H; Konishi, M

    2001-09-21

    Unique stationary phases of octadecylsilica (ODS) coated with acylcarnitines have been developed for liquid chromatographic columns. The ODS column coated with acylcarnitine was readily prepared by recycling the solution containing acylcarnitine through an ODS column in a closed loop. Acylcarnitine was adsorbed on the ODS surfaces by hydrophobic interaction between the acyl group of acylcarnitine and the octadecyl group of the ODS phases. The ODS column coated with stearoylcarnitine (CN-18 column) was the most stable among the four columns coated with acylcarnitines of various acyl chain lengths (decanoylcarnitine, lauroylcarnitine, myristoylcarnitine, and stearoylcarnitine) under the condition of delivery of the mobile phase, indicating that adsorption of acylcarnitine on the ODS surfaces depended on the length of acyl chains. The CN-18 column was usable for delivering the mobile phase contained less than 20% (v/v) acetonitrile, retaining almost the same separation efficiency as the intact ODS column. The retention behavior of ionic solutes on the CN-18 column could be explained by both ionic and electrostatic interactions between the solutes and the stationary phase. The CN-18 column enabled efficient separation of inorganic anions, nicotinic acids, amino acids, and nucleotides. The chiral ODS column coated with enantiomer of stearoylcarnitine, L-stearoylcarnitine (L-CN-18 column) could achieve direct enantiomeric separation of DL-tryptophan, alpha-methyl-DL-tryptophan and DL-3-indolelactic acid using 100% water as the mobile phase. The L-CN-18 column could also separate enantiomers of amino acids and alpha-hydroxycarboxylic acids by ligand-exchange chromatographic mode using a mobile phase containing copper(II) ion. The chiral recognition is discussed for enantiomeric separation on the L-CN-18 column.

  9. Biological assay and liquid chromatographic method for analysis of moxifloxacin in tablets.

    PubMed

    Guerra, Fanny L B; Paim, Clesio S; Steppe, Martin; Schapoval, Elfrides E S

    2005-01-01

    A microbiological assay and a liquid chromatographic method were validated for quantitation of moxifloxacin in tablets. The microbiological method consisted of a cylinder-plate agar diffusion assay using Micrococcus luteus ATCC 9341 as the test microorganism and phosphate buffer (0.1M, pH 8.0) as the diluent solution. The response graphs for standard and sample solutions were linear (r = 0.9479), and no parallelism deviations were detected in the tested levels of concentration (4.0, 8.0, and 16.0 microg/mL). The interday precision was 2.73%. Recovery values were between 96.25 and 100.5%. The chromatographic analyses were performed using a Shim-pack CLC-ODS column (250 x 4.6 mm, 5 microm) with a mobile phase consisting of (A) a mixture of phosphoric acid (0.17%, v/v) with tetramethylammonium hydroxide (0.05M) and acetonitrile (95 + 5, v/v) and (B) methanol (55 + 45, v/v) adjusted to pH 3.0. The flow rate was 1.0 mL/min, and detection was made at 294 nm. The method was linear in a range from 12.0 to 42 microg/mL (r = 0.9999), and the interday precision was 1.39%. Recovery ranged between 101.9 and 103.81%. Both validated methods were used to quantify the moxifloxacin content in tablets exposed to ultraviolet radiation, and similar results were obtained.

  10. [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.

  11. Solvent extraction of low-molecular-weight polycyclic aromatic hydrocarbons from reversed-phase liquid chromatographic effluents

    SciTech Connect

    Ogawa, I.; Chriswell, C.D.

    1982-01-01

    High-performance liquid chromatography provides an effective means of separating constituents of samples of environmental origin. When such samples contain large numbers of constituents at low concentrations, retention times and detector responses provide insufficient data for component characterization. Coupling of HPLC fractionation with GC/MS characterization has proven to be a powerful technique for determining compounds of interest. Reversed-phase HPLC procedures are the most effective for separation of samples containing low-molecular-weight polycyclic aromatic hydrocarbons. However, the aqueous methanol or acetonitrile solvents used with reversed-phase HPLC are incompatible with high-resolution, high-sensitivity gas chromatography. Reversed-phase solvents can be removed from a sample by distillation or by evaporation with an inert gas. Both of these techniques also lead to significant losses of volatile analytes such as low-molecular-weight polycyclic aromatic hydrocarbons. Solvent extraction with large volumes of pentane has been used to isolate polycyclic aromatic hydrocarbons from HPLC effluents containing methanol and from low-pressure liquid chromatographic effluents containing 2-propanol. In the present work it has been demonstrated that low-molecular-weight polycyclic aromatic hydrocarbons can be isolated from reversed-phase HPLC solvents by a one-step solvent extraction using a small volume of solvent. The procedure is rapid and convenient and the use of a small volume of solvent eliminates the need for reducing the volume of extraction solvent by distillation or other techniques. The utility of the method has been demonstrated by the determination of biphenyl on fly ash.

  12. Improvement in Liquid Chromatographic Performance of Organic Polymer Monolithic Capillary Columns with Controlled Free-Radical Polymerization.

    PubMed

    Gama, Mariana R; Aggarwal, Pankaj; Liu, Kun; Lee, Milton L; Bottoli, Carla B G

    2016-12-19

    Capillary columns containing butyl or lauryl methacrylate monoliths were prepared using two different free-radical polymerization methods: conventional free-radical polymerization and controlled/living free-radical polymerization, both initiated thermally, and these methods were compared for the first time. Both monolith morphology and chromatographic efficiency were compared for the synthesized stationary phases using scanning electronic microscopy (SEM) and capillary liquid chromatography, respectively. Columns prepared using controlled method gave better chromatographic performance for both monomers tested. The lauryl-based monolith showed 7-fold improvement in chromatographic efficiency with a plate count of 42,000 plates/m (corrected for dead volume) for a non-retained compound. Columns fabricated using controlled polymerization appeared more homogenous radially with fused small globular morphologies, evaluated by SEM, and lower column permeability. The columns were compared with respect to resolving power of a series of alkylbenzenes under isocratic and gradient elution conditions.

  13. Ultra-High-Pressure Liquid Chromatographic method for the analysis of tocopherols in human colostrum and milk.

    PubMed

    Moltó-Puigmartí, Carolina; Castellote, Ana Isabel; López-Sabater, M Carmen

    2009-05-15

    A rapid, highly sensitive and direct Ultra-High-Pressure Liquid Chromatographic method was developed and validated for quantifying delta-, beta+gamma-, and alpha-tocopherol in human colostrum and milk. Two reversed-phase chromatographic columns and two detectors (Fluorescence Detector or FD and Photodiode Detector Array or PDA) were used and both methods were independently validated. Two internal standards were selected according to the detector used. Recoveries ranged from 96.71% to 103.55% and the relative standard deviations for the within-day precision were below 6% (PDA) and 3% (FD). Both approaches enabled to achieve low detection limits, on the order of ng (PDA) or pg (FD). Only 300muL of sample and a chromatographic run of less than 1.6min were enough to efficiently quantify the isomers in the colostrum and milk of Spanish women.

  14. A new analytical method for quantification of olive and palm oil in blends with other vegetable edible oils based on the chromatographic fingerprints from the methyl-transesterified fraction.

    PubMed

    Jiménez-Carvelo, Ana M; González-Casado, Antonio; Cuadros-Rodríguez, Luis

    2017-03-01

    A new analytical method for the quantification of olive oil and palm oil in blends with other vegetable edible oils (canola, safflower, corn, peanut, seeds, grapeseed, linseed, sesame and soybean) using normal phase liquid chromatography, and applying chemometric tools was developed. The procedure for obtaining of chromatographic fingerprint from the methyl-transesterified fraction from each blend is described. The multivariate quantification methods used were Partial Least Square-Regression (PLS-R) and Support Vector Regression (SVR). The quantification results were evaluated by several parameters as the Root Mean Square Error of Validation (RMSEV), Mean Absolute Error of Validation (MAEV) and Median Absolute Error of Validation (MdAEV). It has to be highlighted that the new proposed analytical method, the chromatographic analysis takes only eight minutes and the results obtained showed the potential of this method and allowed quantification of mixtures of olive oil and palm oil with other vegetable oils. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Sensitive high-performance liquid chromatographic quantitation of gabapentin in human serum using liquid-liquid extraction and pre-column derivatization with 9-fluorenylmethyl chloroformate.

    PubMed

    Bahrami, Gholamreza; Kiani, Amir

    2006-05-01

    Most of the published methods for analysis of gabapentin, an antiepileptic agent, in human serum are based on the same approach, involving o-phthaldialdehyde derivatization of deproteinized serum samples. The present paper however, describes a new, simple and sensitive high-performance liquid chromatographic method for determination of gabapentin in human serum using liquid-liquid extraction and 9-fluorenylmethyl chloroformate (FMOC-Cl) as pre-column labeling agent. The drug and an internal standard (azithromycin) were extracted from serum by salting-out approach using a mixture of dichloromethane-2 propanol (1:1, v/v) as the extracting solvent. The extracted analytes were subjected to derivatization with FMOC-Cl in the presence of phosphate buffer (pH 7). A mobile phase consisting of methanol-0.05 M sodium phosphate buffer (73/27, v/v; pH of 3.9) containing 1 ml/l triethylamine was eluted and chromatographic separation was performed on a Shimpack CLC-C18 (150 mm x 4.6 mm) column. The standard curve was linear over the range of 0.03-20 microg/ml and limit of quantification was 0.03 microg/ml. The performance of analysis was studied and the validated method showed excellent performance in terms of selectivity, specificity, sensitivity, precision and accuracy. No interferences were found from commonly co-administered antiepileptic agents.

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

    PubMed

    Velez, Julian; Thies, Mark C

    2013-11-01

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

  17. Continuous fraction collection of gas chromatographic separations with parallel mass spectrometric detection applied to cell-based bioactivity analysis.

    PubMed

    Jonker, Willem; Stöckl, Jan B; de Koning, Sjaak; Schaap, Jaap; Somsen, Govert W; Kool, Jeroen

    2017-06-01

    We describe the development and evaluation of a GC-MS fractionation platform that combines high-resolution fraction collection of full chromatograms with parallel MS detection. A y-split at the column divides the effluent towards the MS detector and towards an inverted y-piece where vaporized trap solvent is infused. The latter flow is directed outside the GC oven allowing subsequent condensation and stepwise collection of liquid fractions with trapped analytes on a 384-well plate. For study and optimization of the effluent split ratio, restriction capillaries of different lengths and diameters were evaluated. For a wide range of settings, local pressures were monitored during fractionation to assess the influence of MS vacuum and trap solvent infusion on the GC system stability. The platform performance was evaluated by GC-MS analysis and continuous fractionation of an n-alkane mixture followed by GC analysis of each fraction. Comparison of the on-line recorded and fraction-reconstructed chromatogram showed the GC separation is maintained during fractionation. Multiple fractionation cycles of the n-alkane sample on the same 384-well plate yielded a reconstructed chromatogram which was highly similar to that of a single analysis, demonstrating the high repeatability. The applicability of the GC-MS-fractionation platform for bioactivity screening was investigated by applying the AR-Ecoscreen reporter gene bioassay on fractions obtained after analysis of standard solutions and dust samples containing the anti-androgenic compounds vinclozolin and p,p'-DDE. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Ethanol extract and chromatographic fractions of Tamarindus indica stem bark inhibits Newcastle disease virus replication.

    PubMed

    Okoh, Omobola O; Obiiyeke, Grace E; Nwodo, Uchechukwu U; Okoh, Anthony I

    2017-12-01

    The plethora of ethnomedicinal applications of Tamarindus indica Linn. (Leguminosae), tamarind, includes treatment of human and livestock ailments; preparations are recognized antipyretics in fevers, laxatives and carminatives. African folklore has various applications of tamarind. However, in Nyasaland, domestic fowl are fed with preparations for prophylactic properties. The objective of this study is to evaluate the antiviral properties of T. indica extract. Tamarindus indica stem bark was extracted through ethanol maceration over 24 h, and the crude extract was fractionated by gravity-propelled column chromatography. Newcastle disease virus (NDV) inhibitory activity of extract and fractions were evaluated in vivo using 10-d-old embryonated chicken egg (ECE) as the medium for virus cultivation and antivirus assay. About 240 ECE were grouped into eight (three controls and five experimental) and, 200 μL of the extract and fractions respectively inoculated into NDV pre-infected eggs and incubated at 37 °C. Allantoic fluid was harvested 5 d post-virus infection and assayed for haemagglutination (HA). Anti-NDV assessment showed 62.5 mg/mL of crude extract and fractions: TiA, TiC and TiD to yield a HA titre of 1:128 each, while TiB showed 1:64 HA titre. At 125 mg/mL, a titre of 1:16 was recorded against TiB and TiD and, 1:8 against TiA. Similarly, crude extract and TiC, each recorded 1:4 HA titre. However, the minimum concentrations of extract and fraction for virus inactivation were 0.24 mg/mL and 0.49 mg/mL, respectively. The antiviral activity shown by T. indica portends novel antiviral drugs and, perhaps, as scaffold for new drugs.

  19. 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.

  20. Liquid chromatographic method for the simultaneous determination of imipenem and sulbactam in mouse plasma.

    PubMed

    Aparicio, Irene; Bello, Miguel Angel; Callejón, Manuel; Jiménez, Juan Carlos

    2006-10-01

    The first analytical method is developed and validated for the simultaneous determination of imipenem and sulbactam in mouse plasma. Sample treatment is based on plasma stabilization with 4-(2-hydroxyethyl)piperazine-ethanesulfonic acid (HEPES) (0.5 mol/L; pH 7.0)-water-ethylene glycol (2:1:1, v/v/v), precipitation of plasma proteins with acetonitrile, centrifugation, evaporation, and reconstitution with borate buffer. Analytical determination is carried out by high-performance liquid chromatography with diode-array detection. Chromatographic separation is achieved within 11 min on a C(18) column by gradient elution with borate buffer (0.1 mol/L, pH 7.2) and methanol. Imipenem and sulbactam are monitored at 295 and 230 nm, respectively. The overall interday accuracy is in the range of 95% to 100% and from 98% and 101% for imipenem and sulbactam, respectively. Interday precision is below 8% and 4% for imipenem and sulbactam, respectively. Limits of quantitation of imipenem and sulbactam are 0.05 and 1.0 microg/mL, respectively. The mean extraction recoveries are 94.5% and 94.2% for imipenem and sulbactam, respectively. The described method allows an accurate, simple, and rapid identification and quantitation of imipenem and sulbactam in mouse plasma. This method is applied to the analysis of imipenem and sulbactam in mouse plasma after drug administration.

  1. High-performance liquid chromatographic analysis and pharmacokinetics of terazosin in healthy volunteers.

    PubMed

    Kang, B C; Yang, C Q; Rhee, J E; Suh, O K; Shin, W G

    2001-01-01

    A high-performance liquid chromatographic (HPLC) analysis of terazosin in 1 ml of human plasma was developed using prazosin as an internal standard. The plasma sample was extracted with dichloromethane and ethylether and a 100-microl aliquot was injected onto the reversed-phase column. The mobile phase, 0.02 M sodium phosphate buffer:acetonitrile:tetrahydrofuran = 720:220:60 (v/v/v), was run at a flow rate of 0.8 ml/min and the column effluent was monitored using a florescence detector set at 370 and 250 nm for the emission and excitation wave numbers, respectively. The retention times for terazosin and prazosin were approximately 6.4 and 9.8 min, respectively, and the coefficients of variation of terazosin were generally low, below 6.4%. The present HPLC method was successful for the pharmacokinetic study of terazosin in healthy volunteers. Following oral administration of terazosin, 2 mg, to 20 healthy male volunteers, the area under the plasma concentration-time curve from time zero to time infinity was 421 +/- 71.8 ng h/ml and terminal half-life was 9.83 +/- 1.29 h.

  2. High performance liquid chromatographic determination of etofibrate and its hydrolysis products.

    PubMed

    el-Gindy, Alaa; Hadad, Ghada M; Mahmoud, Waleed M M

    2007-01-04

    High performance liquid chromatographic (HPLC) method is presented for the determination of etofibrate (EF) and its hydrolysis products. The method was based on HPLC separation of EF from its hydrolysis products using cyanopropyl column at ambient temperature with mobile phase consisting of acetonitrile-10 mM potassium dihydrogen phosphate, pH was adjusted to 4.1 using phosphoric acid (50:50, v/v). Quantitation was achieved with UV detection at 221 nm based on peak area. The flow rate was 1.5 ml min(-1). The proposed method was used to investigate the kinetics of acidic hydrolysis process of EF at different temperatures and the apparent pseudo first-order rate constant, half-life and activation energy were calculated. The kinetics of alkaline hydrolysis process of EF using 0.01 M sodium hydroxide at different temperatures cannot be studied as the drug is rapidly hydrolyzed in alkaline medium. The pH-rate profile of hydrolysis of EF in Britton-Robinson buffer solutions within the pH range 2-10 were studied.

  3. An improved liquid chromatographic method for the analysis of tylosin and its impurities.

    PubMed

    Ashenafi, Dunge; Hoogmartens, Jos; Adams, Erwin

    2011-10-01

    A selective reversed-phase (RP) liquid chromatographic (LC) method coupled with UV for the determination of tylosin and its related substances is described. The gradient method uses a Capcell pak C18 ACR column (25 cm×4.6 mm id, 5 μm) maintained at a temperature of 60°C. The mobile phases consist of acetonitrile, phosphate buffer pH 5.5 and water: (A; 27.5:10:62.5 v/v/v) and (B; 50:10:40 v/v/v). The flow rate is 1.0 mL/min and UV detection is performed at 280 nm. It allows the separation of all known and 22 other unknown related substances (≥0.02%) from the main compound and from one another. The method shows good precision, sensitivity, linearity (between 0.2 μg/mL and 1.25 mg/mL) and robustness. The limit of quantification is 0.2 μg/mL, corresponding to 0.020%. Seven bulk tylosin samples containing a large number of impurities were examined using this method. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Liquid chromatographic determination of multiple sulfonamides, nitrofurans, and chloramphenicol residues in pasteurized milk.

    PubMed

    Perez, Norma; Gutierrez, Rey; Noa, Mario; Diaz, Gilberto; Luna, Hector; Escobar, Irma; Munive, Zenaida

    2002-01-01

    A rapid and selective liquid chromatographic method was developed to detect 6 sulfonamides, 3 nitrofurans, and chloramphenicol residues in pasteurized milk. The 10 drugs were extracted with chloroform-acetone and the organic phase was evaporated; the residues were dissolved in an aqueous sodium acetate buffer solution 0.02M (pH = 4.8), and the fat was removed by washing with hexane. The aqueous layer was collected, filtered, and injected. The 6 sulfonamides and chloramphenicol were detected at 275 nm ultraviolet (UV) using a gradient system starting with sodium acetate buffer solution-acetonitrile (95 + 5) and finishing with sodium acetate buffer solution-acetonitrile (80 + 20). Nitrofurans were detected at 375 nm (UV) isocratically with sodium acetate buffer solution-acetonitrile (80 + 20). For 50 ppb fortified milk, the average recoveries were (sulfathiazole) 65.52%; (sulfamerazine) 75.36%; (sulfamethazine) 93.94%; (sulfachlorpyridazine) 75.94%; (sulfamethoxazole) 85.18%; (sulfamonomethoxine) 83.45%; (chloramphenicol) 104.17%; (nitrofurazone) 91.81%; (furazolidone) 100.76%; and (furaltadone) 72.38%. Method detection limits ranged from 4 ppb (nitrofurazone) to 16 ppb (sulfamethazine). Some matrix interferences (3-7 ppb) were observed only with sulfonamides.

  5. 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.

  6. 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.

  7. Liquid chromatographic determination of organic nitrogenous bases in dosage forms: a progress report.

    PubMed

    Walker, S T

    1985-01-01

    A liquid chromatographic (LC) method has been developed as a general procedure for the assay of the salts of organic nitrogenous bases in a variety of dosage forms. The method uses a nitrile-bonded reverse phase column, a methanol-0.003M ammonium acetate (90 + 10) mobile phase, and photometric detection at 254 nm. The sample is dissolved in the mobile phase and an aliquot is injected through a 20 microL injection loop. Average recovery values for duplicate assays were chlorpheniramine maleate injection 97.8%, chlorpheniramine maleate tablets 99.1%, cyclizine hydrochloride tablets 100.0%, doxylamine succinate tablets 103.3%, mesoridazine besylate tablets 100.4%, pentazocine hydrochloride tablets 103.0%, promethazine hydrochloride injection 98.4%, protriptyline hydrochloride tablets 101.2%, pyrilamine maleate tablets 97.8%, pyrimethamine tablets 100.0%, tripelennamine citrate elixir 100.0%, and tripelennamine hydrochloride tablets 97.2%. Results by this method were in good agreement with those obtained by the USP XX method. This study, which is being continued, will be expanded to include additional drugs.

  8. 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%).

  9. A reversed phase high performance liquid chromatographic method for determination of rapamycin.

    PubMed

    Sobhani, Hamideh; Shafaati, Alireza; Nafissi-Varcheh, Nastaran; Aboofazeli, Reza

    2013-01-01

    Easily degradating and various isomeric forms of rapamycin (Sirolimus) face the determination of this compound to many challenges. In this study, we developed and validated the isocratic reversed phase high performance liquid chromatographic (RP-HPLC) method for rapamycin. Separation was performed on a C8 column (MZ, 15 × 4.6 mm, 5 μm particle size) using methanol:water (80:20 v/v) as the mobile phase with the flow rate of 1 mL/min. The column temperature was set at 57°C and the detection was carried out at the wavelength of 277 nm. The method was linear over a concentration range of 0.025-2 μg/mL. The coefficient of variation of intra- and inter-day, assessed at three concentration levels of 0.075, 0.3 and 0.900 μg/mL, was less than 2%. Limit of quantification (LOQ) was found 25 ng/mL. The method with high percent recovery and short retention time of rapamycin, was found to be simple, rapid and reproducible.

  10. Brain penetration of colistin in mice assessed by a novel high-performance liquid chromatographic technique.

    PubMed

    Jin, Liang; Li, Jian; Nation, Roger L; Nicolazzo, Joseph A

    2009-10-01

    A sensitive and reliable liquid chromatographic method was developed and validated for the determination of colistin concentrations in mouse brain homogenate. With a mobile phase consisting of acetonitrile-tetrahydrofuran-water (50:25:25 [vol/vol]) at a flow rate of 1 ml/min, a linear correlation between peak area and colistin concentration was observed over the concentration range of 93.8 to 3,000 ng/g in brain tissue (R2 > 0.994). Intra- and interday coefficients of variation were 5.1 to 8.3% and 5.8 to 8.5%, respectively, and the recovery ranged from 85% to 94%. This assay was then utilized to determine the amount of colistin that permeated the blood-brain barrier over a 2-h period following bolus intravenous administration of colistin sulfate to mice. After a single dose of 5 mg/kg of body weight to mice, brain homogenate concentrations of colistin were very low, relative to plasma colistin concentrations, suggesting that colistin permeability across the healthy blood-brain barrier is negligible during this experimental period.

  11. Improved high-performance liquid chromatographic method for the determination of coenzyme Q10 in plasma.

    PubMed

    Grossi, G; Bargossi, A M; Fiorella, P L; Piazzi, S; Battino, M; Bianchi, G P

    1992-02-28

    Coenzyme (Co) Q10 was dissociated from lipoproteins in plasma by treatment with methanol and extraction with n-hexane. Subsequent clean-up on silica gel and C18 solid-phase extraction cartridges with complete recovery (99 +/- 1.2%) produced a clean extract. High-performance liquid chromatographic (HPLC) separation was performed on a C18 reversed-phase column. Three simple, rapid procedures are presented: HPLC with final UV (275 nm) detection, a microanalysis utilizing a three-electrode electrochemical detector and a microanalysis with column-switching HPLC and electrochemical detection. The methods correlate very well with classical ethanol-n-hexane extraction with UV detection. The identity and purity of the Co Q10 peak were investigated and the resulting methods were concluded to be suitable for total plasma Co Q10 determination. The average level in healthy subjects was 0.80 +/- 0.20 mg/l; the minimum detectable Co Q10 plasma level was 0.05 and 0.005 mg/l for UV and electrochemical detection, respectively. The methods were applied to many samples and the plasma Co Q10 reference values for healthy subjects, athletes, hyperthyroid, hypothyroid and hypercholesterolaemic patients are given.

  12. A sensitive high-performance liquid chromatographic analysis of propranolol in serum.

    PubMed

    al-Angary, A A; el-Sayed, Y M; al-Meshal, M A; al-Dardiri, M M; Mahrous, G M

    1991-04-01

    A rapid and sensitive high-performance liquid chromatographic (HPLC) assay was developed for quantitative determination of propranolol in serum. The assay is performed after single extraction of propranolol and indenolol [internal standard (IS)] from alkalinized serum into ether and eluted from C-18 U Bondapak column with a mobile phase composed of methanol: 0.01 M phosphate buffer pH 3.4 (40:60%, v/v). The column eluant was monitored on a fluorescence detector. Measurement was achieved by taking the peak height ratio of propranolol and comparing it to that of the IS. The detection limit for propranolol in serum is 2.5 ng/ml. Intraday coefficients of variation (CV) ranged from 2.84 to 4.0% and interday (CVs) from 5.8 to 8.4% at three different concentrations. The relative and absolute recoveries varied from 93.8 to 102.3%. Preliminary stability tests showed that propranolol is stable for at least 3 weeks in serum after freezing. The method is applied for the determination of the pharmacokinetic parameters of propranolol after intravenous administration (1 mg/kg) to rabbits.

  13. Liquid chromatographic determination of acriflavine and proflavine residues in channel catfish muscle.

    PubMed

    Plakas, S M; el Said, K R; Jester, E L; Bencsath, F A; Hayton, W L

    1997-01-01

    A liquid chromatographic (LC) method was developed for determination of acriflavine (ACR) and proflavine (PRO) residues in channel catfish muscle. Residues were extracted with acidified methanol solution, and extracts were cleaned up with C18 solid-phase extraction columns. Residue concentrations were determined on an LC cyano column, with spectrophotometric detection at 454 nm. Catfish muscle was individually fortified with ACR (purified from commercial product) and PRO at concentrations of 5, 10, 20, 40, and 80 ppb (5 replicates per level). Mean recoveries from fortified muscle at each level ranged from 86 to 95%, with relative standard deviations (RSDs) of 2.5 to 5.7%. The method was applied to incurred residues of ACR and PRO in muscle after waterborne exposure of channel catfish to commercial acriflavine (10 ppm total dye for 4 h). RSDs for incurred residues of ACR and PRO were in the same range as those for fortified muscle. Low residue concentrations (< 1% of exposure water concentration) suggested poor absorption of ACR and PRO in catfish.

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

    PubMed

    Carlson, M; Thompson, R D

    1997-01-01

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

  15. A simple high-performance liquid chromatographic assay for ciprofloxacin in human serum.

    PubMed

    Jim, L K; el-Sayed, N; al-Khamis, K I

    1992-04-01

    A simple and selective high-performance liquid chromatographic (HPLC) method for the determination of ciprofloxacin in serum has been developed and evaluated. Serum protein was precipitated with acetonitrile. The drug and the internal standard (quinine) were evaluated from a 10 microns U-Bondapack C-18 cartridge at ambient temperature with a mobile phase consisting of acetonitrile: 0.1 M sodium dihydrogen phosphate (20:80%, v/v) adjusted to pH 3.9 with phosphoric acid, and at a flow rate of 2.5 ml/min. The effluent was monitored on a fluorescence detector using an excitation and emission wavelength of 280 and 455 nm, respectively. Each analysis required no longer than 6 min. Quantification was achieved by the measurement of the peak-height ratio and the limit of quantification for ciprofloxacin in serum is 25 ng/ml. The intraday coefficient of variation (CV) ranged from 0.4 to 5.8%, and interday CV from 4.6 to 8.8% at three different concentrations. Relative recovery ranged from 98 to 100.2% at three different concentrations. Preliminary stability tests show that ciprofloxacin is stable for at least 3 weeks in serum after freezing.

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

    PubMed

    Liu, T; Wu, D

    2012-10-01

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

  17. High-performance liquid chromatographic phenolic compound fingerprint for authenticity assessment of honey.

    PubMed

    Cavazza, Antonella; Corradini, Claudio; Musci, Marilena; Salvadeo, Paola

    2013-03-30

    Phenolic compound profiles of 20 honeys of different botanical origin (eucalyptus, citrus, chestnut and linden) were obtained by high-performance liquid chromatography with ultraviolet detection after solid phase extraction, in order to evaluate the effectiveness of the fingerprint method for monofloral honey discrimination. A total of 58 peaks were detected at λ = 280 nm. Distinctive phenolic compound profiles were obtained in which both the nature and the relative amount of the detected compounds were characteristic for different botanical source honeys. In order to detect sample groupings, chromatographic peak areas were submitted to principal component analysis. Then linear discriminant analysis was carried out on the first three principal components. In addition, linear discriminant analysis was carried out on the 58 variables, allowing the selection of five variables able to discriminate honeys of different botanical origin. The chemometric evaluation of the phenolic compound profiles yielded classification models able to group honey samples according to their floral source with an excellent degree of agreement. The main advantage of the fingerprint approach with respect to traditional methods is that it does not require time-consuming identification and quantification of the analytes. The method proved to be effective for the assessment of honey authenticity. © 2012 Society of Chemical Industry.

  18. New liquid chromatographic method for determination of rabeprazole sodium in coated tablets.

    PubMed

    Garcia, Cássia V; Paim, Clésio S; Steppe, Martin

    2004-01-01

    Rabeprazole sodium is a proton pump inhibitor that covalently binds and inactivates the gastric parietal cell proton pump (H+/K+ ATPase). Little has been published about the quantitative determination of this drug. The aim of this research was to develop a new liquid chromatographic method for quantitative determination of rabeprazole in coated tablets. The system consisted of a Hypersil Keystone Betabasic C8 column (250 x 4.6 mm, 5 microm particle size), an isocratic acetonitrile-water (35 + 65) mobile phase at a flow rate of 1.0 mL/min, and a diode array detector set at 282 nm. The following validation parameters were evaluated: linearity, precision, accuracy, specificity, detection and quantitation limits, and robustness. The method showed good linearity in the concentration range of 10-70 microg/mL. The quantitation limit was 2.43 microg/mL, and the detection limit was 0.80 microg/mL. The intra- and interday precision data showed that the method has good reproducibility (relative standard deviation = 1.03). Accuracy and robustness were also evaluated, and the results were satisfactory. The mean recovery was 101.61%. The analysis of a placebo mixture demonstrated the method is also specific.

  19. Reversed-phase high-performance liquid chromatographic determination of mitomycin C in human serum.

    PubMed

    Buice, R G; Sidhu, P; Gurley, B J; Niell, H B

    1984-01-01

    A reversed-phase high-performance liquid chromatographic method is presented by which the cancer chemotherapeutic agent, mitomycin C, may be measured in human serum. A mobile phase of methanol:water (35:65) passed through a mu-Bondapak C-18 column at a rate of 1.0 ml/min produced a sharp, symmetrical band for mitomycin C. An improved serum extraction procedure, using a reversed-phase sample preparation cartridge, proved to be efficient and reproducible. Recovery over a concentration range of 10-100 ng/ml was 81.6% with a between-day coefficient of variation of 4.6% (n = 5). The within-day coefficient of variation at 50 ng/ml was 5.6% (n = 10). Ultraviolet detection at a wavelength of 365 nm was sensitive to serum concentrations of 10 ng/ml. Serum concentration-time course data from lung cancer patients receiving mitomycin C by rapid intravenous injection are presented.

  20. Simplified high-performance liquid chromatographic determination of residual amprolium in edible chicken tissues.

    PubMed

    Furusawa, N

    2002-07-01

    A simplified determining method for the routine monitoring of residual amprolium in edible chicken tissues (muscle and liver) is developed using a high-performance liquid chromatographic (HPLC) method with a photodiode-array detector after sample cleanup by an Ultrafree-MC/PL centrifugal ultrafiltration unit. For the HPLC determination and identification, a Mightysil RP4 GP column and a mobile phase of an ethanol-5 mM 1-heptanesulfonic acid sodium salt solution (35:65, v/v) using an ion-pairing system with a photodiode-array detector are used. Average recoveries (spiked at 0.3-3.0 microg/g) are > 90%. The inter- and intravariabilities are 1.9-2.4%. The limits of quantitation are 0.22 microg/g for muscle and 0.25 microg/g for liver. The total time and solvent required for the analysis of one sample are < 20 min and < 2 mL of ethanol, respectively. No toxic solvents and regents are used.

  1. Simplified high-performance liquid chromatographic determination of residual amprolium in edible chicken tissues.

    PubMed

    Furusawa, N

    2002-08-01

    A simplified determining method for the routine monitoring of residual amprolium in edible chicken tissues (muscle and liver) is developed using a high-performance liquid chromatographic (HPLC) method with a photodiode-array detector after sample cleanup by an Ultrafree-MC/PL centrifugal ultrafiltration unit. For the HPLC determination and identification, a Mightysil RP-4 GP column and a mobile phase of an ethanol-5 mM 1-heptanesulfonic acid sodium salt solution (35:65, v/v) using an ion-pairing system with a photodiode-array detector are used. Average recoveries (spiked at 0.3-3.0 microg/g) are > 90%. The inter- and intravariabilities are 1.9-2.4%. The limits of quantitation are 0.22 microg/g for muscle and 0.25 microg/g for liver. The total time and solvent required for the analysis of one sample are < 20 min and < 2 mL of ethanol, respectively. No toxic solvents and regents are used.

  2. Reverse phase liquid chromatographic determination and confirmation of aflatoxin M1 in cheese.

    PubMed

    Hisada, K; Terada, H; Yamamoto, K; Tsubouchi, H; Sakabe, Y

    1984-01-01

    A systematic method is proposed for determination and confirmation of aflatoxin M1 in cheese by liquid chromatography (LC). A sample of cheese is extracted with chloroform, cleaned up on 2 silica gel columns followed by a Sep-Pak C18 cartridge, and chromatographed on a 5 microns octadecyl silica column with fluorometric detection. The sample extract or standard is treated with n-hexane-trifluoroacetic acid (TFA) (4 + 1) for 30 min at 40 degrees C. Analysis by LC with TFA-treatment of the extract provides quantitative data. Multiple assays of 5 samples of Gouda cheese spiked with aflatoxin M1 at levels of 0.5, 0.1, and 0.05 ng/g showed average recoveries of 93.2, 91.6, and 92.4%, with coefficients of variation of 2.63, 3.97, and 4.52%, respectively. Assay of 5 naturally contaminated cheeses resulted in 0.051-0.448 ng/g of aflatoxin M1. Limit of quantitation is about 0.01 ng/g. The identity of aflatoxin M1 is confirmed by treating aflatoxin M1 or the M2a derivative with TFA-methanol (or ethanol) (3 + 1). The TFA-methanol reaction products of M2a could be detected quantitatively.

  3. Micellar liquid chromatographic analysis of benzyl alcohol and benzaldehyde in injectable formulations.

    PubMed

    Rizk, Mohamed; Ibrahim, Fawzia; Hefnawy, Mohamed; Nasr, Jenny Jeehan

    2007-06-01

    An accurate, sensitive and selective reversed-phase micellar liquid chromatographic method was developed for simultaneous determination of benzyl alcohol and benzaldehyde. This method was applied in different injectable formulations containing diclofenac, piroxicam, lincomycin and clindamycin. The method showed excellent linearity in the range of 10-100 microg mL(-1) and 1-20 microg mL(-1) with the limit of detection (S/N = 3) 0.25 microg mL(-1) (2.3 x 10(-6) mol L(-1)) and 0.12 microg mL(-1) (1.13 x 10(-6) mol L(-1)) for benzyl alcohol and benzaldehyde, respectively. The suggested method was successfully applied to the analysis of the studied drugs in bulk with average recoveries of 100.1 +/- 1.0% for benzyl alcohol and 100.4 +/- 1.6% for benzaldehyde, and to the determination of benzyl alcohol and benzaldehyde in injectable formulations with the respective average recoveries of 99.8 +/- 0.3 and 100.0 +/- 0.4%.

  4. High-performance liquid chromatographic method for the determination of moniliformin in corn.

    PubMed

    Munimbazi, C; Bullerman, L B

    1998-01-01

    A high-performance liquid chromatographic method using UV absorption was developed for determining moniliformin in corn. The toxin was extracted with water containing 1% tetrabutylammonium hydrogen sulfate (w/v). Paired moniliformin was partitioned into dichloromethane, which was evaporated to dryness at 50 degrees C. The residue was dissolved in water and applied to a disposable strong-anion exchange solid-phase extraction tube. Adsorbed moniliformin was eluted from the tube with 0.05M sodium dihydrogen phosphate monohydrate (pH 5). It was determined by ion-pair reversed-phase chromatography and UV measurement at 229 nm. The minimum detectable amount of pure moniliformin was 0.25 ng/injection (signal-to-noise ratio = 3:1). The detector response was linear from 0.25 to at least 20 ng. The limit of determination was 0.025 microgram/g corn. Recoveries of moniliformin from corn spiked at 0.025, 0.05, 0.25, and 1.0 microgram/g averaged 96.5, 96.2, 97.2, and 97.8% respectively.

  5. Practical method for the definition of chromatographic peak parameters in preparative liquid chromatography.

    PubMed

    Jin, Gaowa; Guo, Zhimou; Xiao, Yuansheng; Yan, Jingyu; Dong, Xuefang; Shen, Aijin; Wang, Chaoran; Liang, Xinmiao

    2016-10-01

    A practical method was established for the definition of chromatographic parameters in preparative liquid chromatography. The parameters contained both the peak broadening level under different amounts of sample loading and the concentration distribution of the target compound in the elution. The parameters of the peak broadening level were defined and expressed as a matrix, which consisted of sample loading, the forward broadening and the backward broadening levels. The concentration distribution of the target compound was described by the heat map of the elution profile. The most suitable stationary phase should exhibit the narrower peak broadening and it was best to broaden to both sides to compare to the peak under analytical conditions. Besides, the concentration distribution of the target compounds should be focused on the middle of the elution. The guiding principles were validated by purification of amitriptyline from the mixture of desipramine and amitriptyline. On the selected column, when the content of the impurity desipramine was lower than 0.1%, the recovery of target compound was much higher than the other columns even when the sample loading was as high as 8.03 mg/cm(3) . The parameters and methods could be used for the evaluation and selection of stationary phases in preparative chromatography.

  6. 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

  7. 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.

  8. 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

  9. High-performance liquid chromatographic determination of tianeptine in plasma applied to pharmacokinetic studies.

    PubMed

    Gaulier, J M; Marquet, P; Lacassie, E; Desroches, R; Lachatre, G

    2000-10-10

    An improved analytical method for the quantitative measurement of tianeptine and its main metabolite MC5 in human plasma was designed. Extraction involved ion-paired liquid-liquid extraction of the compounds from 1.0 ml of human plasma adjusted to pH 7.0. HPLC separation was performed using a Nucleosil C18, 5 microm column (150x4.6 mm I.D.) and a mixture of acetonitrile and pH 3, 2.7 g l(-1) solution of sodium heptanesulfonate in distilled water (40:60, v/v) as mobile phase. UV detection was performed using a diode array detector in the 200-400 nm passband, and quantification of the analytes was made at 220 nm. For both tianeptine and MC5 metabolite, the limit of quantitation was 5 microg l(-1) and the calibration curves were linear from 5 to 500 microg l(-1). Intra- and inter-assay precision and accuracy fulfilled the international requirements. The recovery of tianeptine and its metabolite from plasma was, respectively, 71.5 and 74.3% at 20 microg l(-1), 71.2 and 70.8% at 400 microg l(-1). The selectivity of the method was checked by verifying the absence of chromatographic interference from pure solutions of the most commonly associated therapeutic drugs. This method, validated according to the criteria established by the Journal of Chromatography B, was applied to the determination of tianeptine and MC5-metabolite in human plasma in pharmacokinetic studies.

  10. Mercury isotope fractionation during liquid-vapor evaporation experiments

    NASA Astrophysics Data System (ADS)

    Estrade, Nicolas; Carignan, Jean; Sonke, Jeroen E.; Donard, Olivier F. X.

    2009-05-01

    Liquid-vapor mercury isotope fractionation was investigated under equilibrium and dynamic conditions. Equilibrium evaporation experiments were performed in a closed glass system under atmospheric pressure between 0 and 22 °C, where vapor above the liquid was sampled at chemical equilibrium. Dynamic evaporation experiments were conducted in a closed glass system under 10 -5 bar vacuum conditions varying (1) the fraction of liquid Hg evaporated at 22 °C and (2) the temperature of evaporation (22-100 °C). Both, residual liquid and condensed vapor fractions were analyzed using stannous chloride CV-MC-ICP-MS. Equilibrium evaporation showed a constant liquid-vapor fractionation factor ( α202/198) of 1.00086 ± 0.00022 (2SD, n = 6) within the 0-22 °C range. The 22 °C dynamic evaporations experiments displayed Rayleigh distillation fractionation behavior with liquid-vapor α202/198 = 1.0067 ± 0.0011 (2SD), calculated from both residual and condensed vapor fractions. Our results confirm historical data (1920s) from Brönsted, Mulliken and coworkers on mercury isotopes separation using evaporation experiments, for which recalculated δ 202Hg' showed a liquid-vapor α202/198 of 1.0076 ± 0.0017 (2SD). This liquid-vapor α202/198 is significantly different from the expected kinetic α202/198 value ((202/198) 0.5 = 1.0101). A conceptual evaporation model of back condensation fluxes within a thin layer at the liquid-vapor interface was used to explain this discrepancy. The δ 202Hg' of condensed vapor fractions in the 22-100 °C temperature range experiments showed a negative linear relationship with 10 6/ T2, explained by increasing rates of exchange within the layer with the increase in temperature. Evaporation experiments also resulted in non-mass-dependent fractionation (NMF) of odd 199Hg and 201Hg isotopes, expressed as Δ 199Hg' and Δ 201Hg', the deviation in ‰ from the mass fractionation relationship with even isotopes. Liquid-vapor equilibrium yielded Δ 199Hg

  11. High pressure liquid chromatographic determination of 4,4'-(diazoamino)-dibenzenesulfonic acid in FD&C yellow no. 6.

    PubMed

    Marmion, D M

    1977-01-01

    Fourteen analysts from 9 laboratories evaluated a high pressure liquid chromatographic procedure for the determination of 4,4'-(diazoamino)-dibenzenesulfonic acid (DAADBSA) in FD&C Yellow No. 6. Each collaborator analyzed 5 samples nominally containing 0-0.050% DAADBSA. The repeatability and reproducibility of the method are estimated to be 0.003% and 0.020%, respectively. The method has been adopted as offical fist action.

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

    PubMed

    Carlson, M; Thompson, R D

    1998-01-01

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

  13. Comprehensive multi-dimensional liquid chromatographic separation in biomedical and pharmaceutical analysis: a review.

    PubMed

    Dixon, Steven P; Pitfield, Ian D; Perrett, David

    2006-01-01

    'Multi-dimensional' liquid separations have a history almost as long as chromatography. In multi-dimensional chromatography the sample is subjected to more than one separation mechanism; each mechanism is considered an independent separation dimension. The separations can be carried out either offline via fraction collection, or directly coupled online. Early multi-dimensional separations using combinations of paper chromatography, electrophoresis and gels, in both planar and columnar modes are reviewed. Developments in HPLC have increased the number of measurable analytes in ever more complex matrices, and this has led to the concept of 'global metabolite profiling'. This review focuses on the theory and practice of modern 'comprehensive' multi-dimensional liquid chromatography when applied to biomedical and pharmaceutical analysis.

  14. Effect of hawthorn (Crataegus oxycantha) crude extract and chromatographic fractions on multiple activities in a cultured cardiomyocyte assay.

    PubMed

    Long, S R; Carey, R A; Crofoot, K M; Proteau, P J; Filtz, T M

    2006-11-01

    Extracts of hawthorn (Crataegus oxycantha) have become popular herbal supplements for their well-recognized cardiotonic effects. Many commercial preparations have been used successfully in the treatment of congestive heart failure, although the active principles within these extracts have yet to be conclusively identified. Several hawthorn preparations were studied and found to have negative chronotropic effects in a cultured neonatal murine cardiomyocyte assay using unpaced cells. As compared to conventional cardiac drugs (i.e., epinephrine, milrinone, ouabain, or propranolol), hawthorn extract has a unique activity profile. Hawthorn extract appears to be anti-arrhythmic and capable of inducing rhythmicity in quiescent cardiomyocytes. Hawthorn extract does not cause beta-adrenergic receptor blockade at concentrations which cause negative chronotropic effects. Commercial hawthorn preparations, extracts prepared from dried leaves and those made from dried berries have similar chronotropic activities. When crude extracts are separated using size-exclusion chromatography, several fractions retain multiple cardiac activities. Assays with chromatographic fractions reveal that multiple dissimilar cardioactive components may exist within the extract, making the identification of individual active constituents more challenging.

  15. 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.

  16. 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...

  17. 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...

  18. Analysis of fat-soluble vitamins. XXVIII. High performance liquid chromatographic determination of vitamin D in pet foods and feeds: collaborative study.

    PubMed

    de Vries, E J; Van Bemmel, P; Borsje, B

    1983-05-01

    A high performance liquid chromatographic (HPLC) method for vitamin D in pet foods and feeds at low concentrations (2-8 IU/g = 50-200 ppb) was studied collaboratively. The procedure consists of the following purification steps: saponification, extraction of the unsaponifiable fraction, chromatography on alumina, cleanup on reverse phase HPLC, and quantitation with straight phase HPLC. The original method, developed by Knapstein, was simplified by deleting the quantitative TLC step. Six coded samples were distributed to 31 laboratories, along with a known sample containing 15 IU/g to allow practice of the rather complicated procedure. Eighteen collaborators returned their results. Results for the spiked samples show good recovery. The estimates of repeatability and reproducibility are 0.96 and 2.2 IU/g for spiked samples and 1.5 and 3.1 IU/g for commercial samples, respectively, which are considered acceptable for these low concentrations. The method has been adopted official first action.

  19. Considerations on the temperature dependence of the gas-liquid chromatographic retention.

    PubMed

    González, Francisco Rex

    2002-01-04

    A discussion on the temperature dependence of the partition coefficient K is developed. This discussion embraces topics such as the limitations of conventional thermodynamic approaches followed in the chromatographic literature, qualitative theoretical notions arising from molecular thermodynamics and the experimental information that is accessible through modern capillary gas chromatography. It is shown that the heat capacity difference of solute transfer for flexible molecules has at least one maximum in the chromatographic range of temperature. As a consequence, a great amount of experimental data is required for a correct thermodynamic interpretation of the chromatographic retention.

  20. 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.

  1. High-Performance Liquid Chromatographic Method for Determination of Phenytoin in Rabbits Receiving Sildenafil

    PubMed Central

    Khedr, Alaa; Moustafa, Mohamed; Abdel-Naim, Ashraf B.; Alahdal, Abdulrahman; Mosli, Hisham

    2008-01-01

    A validated high-performance liquid chromatographic (HPLC) method for determination of phenytoin (PHN), para-hydroxy metabolite of phenytoin (POH) and sildenafil (SIL) in rabbit plasma is described. The method is based on extraction on Sep-Pak C18 solid support using ethyl acetate and ether as eluents and monitoring at 220 nm. The extracted samples were analyzed by HPLC using Agilent Zorbax Extended C18 column (150 mm × 4.6 mm internal diameter) and isocratic elution with a mobile phase consist of 29% acetonitrile and 71% sodium acetate solution (0.02 M, pH 4.6). The method was fully validated for linearity and range, selectivity, precision, stability, recovery, and robustness. The linearity of the method was in the range of 0.15 to 39 μg /ml for PHN and 0.15 to 33 μg/ml for both POH and SIL. Limits of detection (LOD) of PHN, POH, and SIL were 0.15 ± 0.01, 0.15 ± 0.01, and 0.15 ± 0.01 μg/ml, respectively. The % recovery of PHN, POH, and SIL from rabbit plasma were, 101.88 ± 0.12, 99.16 ± 0.25, and 99.49 ± 0.33, respectively. The method was applied on plasma collected from rabbits at different time intervals after receiving 30 mg/kg PHN-Na with (and without) 8 mg/kg SIL citrate. PMID:19609390

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

    PubMed

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

    2015-09-18

    Identification of small molecules by liquid chromatography-mass spectrometry (LC-MS) can be greatly improved if the chromatographic retention information is used along with mass spectral information to narrow down the lists of candidates. Linear retention indexing remains the standard for sharing retention data across labs, but it is unreliable because it cannot properly account for differences in the experimental conditions used by various labs, even when the differences are relatively small and unintentional. On the other hand, an approach called "retention projection" properly accounts for many intentional differences in experimental conditions, and when combined with a "back-calculation" methodology described recently, it also accounts for unintentional differences. In this study, the accuracy of this methodology is compared with linear retention indexing across eight different labs. When each lab ran a test mixture under a range of multi-segment gradients and flow rates they selected independently, retention projections averaged 22-fold more accurate for uncharged compounds because they properly accounted for these intentional differences, which were more pronounced in steep gradients. When each lab ran the test mixture under nominally the same conditions, which is the ideal situation to reproduce linear retention indices, retention projections still averaged 2-fold more accurate because they properly accounted for many unintentional differences between the LC systems. To the best of our knowledge, this is the most successful study to date aiming to calculate (or even just to reproduce) LC gradient retention across labs, and it is the only study in which retention was reliably calculated under various multi-segment gradients and flow rates chosen independently by labs. Copyright © 2015 Elsevier B.V. All rights reserved.

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

    PubMed

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

    2011-02-01

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

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

    PubMed

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

    1984-09-01

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

  5. 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

  6. 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.

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

    PubMed

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

    2013-02-08

    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%). Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Liquid chromatographic analysis of vitamin B6 in reconstituted infant formula: collaborative study.

    PubMed

    Mann, Dudley L; Ware, George M; Bonnin, Evelyn; Eitenmiller, Ronald R; Barna, Eva; Christiansen, Scott; De Borde, Jean Luc; DeVries, Jonathan; Gilliland, Pamela; Hemmer, Jane; Kalman, Andras; Konings, Erik; Levin, David; Salvati, Louis; Woollard, David

    2005-01-01

    A liquid chromatographic (LC) method was validated for the determination of total vitamin B6 in infant formula. Total vitamin B6 was quantified by converting the phosphorylated and free vitamers into pyridoxine. Pyridoxine was determined by ion pair reversed-phase LC with fluorescence detection. The method was subjected to an AOAC collaborative study involving a factory-manufactured, milk- and soy-based infant formula. Each was spiked at 3 concentrations in the range of 0-1 microg/g and sent as blind duplicate to participant laboratories. Nine laboratories returned valid data which were statistically analyzed for outliers and precision parameters. The repeatability relative standard deviation (RSD(r)) ranges were 2.0-4.0 and 3.5-5.9% for fortified milk- and soy-based formulas, respectively. The reproducibility relative standard deviation (RSD(R)) ranges were 8.2-8.4 and 6.7-11.2% for fortified milk- and soy-based formulas, respectively. HORRAT values ranged from 0.42 to 0.53, indicating that the precision of the method is acceptable. The mean RSD(r):RSD(R) values were 0.60 and 0.55 for milk- and soy-based formulas, respectively. As expected, RSDs for the unfortified samples were higher, but their HORRAT values (0.81 and 2.06) helped define a realistic limit of quantitation as 0.05 microg/g. Recovery data were quantitative and varied between 81.4 and 98.0% (mean = 89.8%) for each of 6 spiked materials.

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

    PubMed

    Krause, R T

    1989-01-01

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

  10. Reversed-phase liquid chromatographic retention and membrane activity relationships of local anesthetics.

    PubMed

    Tsuchiya, Hironori; Mizogami, Maki; Takakura, Ko

    2005-05-06

    The chromatographic retention and membrane activity relationships of local anesthetics were studied to address the possible mechanisms for structure specificity and inflammation-associated decrease of their effects. Five representative drugs (3 mM for each) were reacted with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine liposomes in 25 mM potassium phosphate buffer (pH 5.9-7.9, containing 100 mM NaCl and 0.1 mM EDTA) for 10 min at 37 degrees C and the membrane fluidity changes were analyzed by measuring fluorescence polarization with 1,6-diphenyl-1,3,5-hexatriene. Their capacity factors were determined on octadecyl-, octyl- and phenyl-bonded silica columns with a mobile phase consisting of 25 mM potassium phosphate buffer (pH 5.9-7.9, containing 100 mM NaCl and 0.1 mM EDTA)-methanol (30:70, v/v) at a flow rate of 1.0 ml/min and at a column temperature of 37 degrees C and diode-array detection. Mepivacaine, prilocaine, lidocaine, ropivacaine and bupivacaine fluidized membranes in increasing order of intensity, which agreed with their clinical potency. The relative degree of membrane fluidization correlated with that of retention on an octadecyl stationary phase more significantly than the other phases. Both membrane-fluidizing effects and capacity factors decreased by lowering the reaction and mobile phase pH, being consistent with the hypothesis that anesthetic potency is reduced in inflammation because of tissue acidity. Reversed-phase liquid chromatography appears to be useful for estimating the structure-specific and pH-dependent membrane-fluidizing effects of local anesthetics.

  11. High-Performance Liquid-Chromatographic Analysis of Plasma Iohexol Concentrations.

    PubMed

    Schwertner, Harvey A; Weld, Kyle J

    2015-10-01

    In this study, a high-performance liquid-chromatographic (HPLC) method using photodiode array detection and isocratic conditions was developed for the analysis of plasma iohexol concentrations. Plasma proteins were precipitated with 1:1 volume of plasma and acetonitrile-ethanol-water (60:38.4:1.6, v/v/v). Iohexol concentrations in the supernatant phase were analyzed on a Waters Symmetry C-18 reversed-phase column under isocratic conditions at 245 nm. The extraction recoveries of iohexol from plasma were >95% and the plasma iohexol calibration curves were linear (R(2) ≥ 0.9998) from 10 to 1500 µg/mL. The within-day coefficients of variation (CVs) at plasma iohexol concentrations of 100, 375, 750 and 1500 µg/mL were 5.1, 3.5, 1.3 and 2.5%, respectively; the between-day CVs at 100, 375, 750 and 1500 µg/mL were 8.6, 4.2, 4.0 and 3.7%, respectively. The day-to-day accuracies of the method at plasma iohexol concentrations of 50, 100, 375, 750 and 1500 µg/mL were 89.0, 99.4, 108.4, 103.6 and 101.2%, respectively (n = 5). The lower limit of plasma iohexol quantitation was 10 µg/mL and no interferences >9 µg/mL were found in over 75 pre-dose porcine plasma samples. The applicability of the method was demonstrated by determining the glomerular filtration rates of iohexol in the porcine (Sus scrofa) model.

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

    PubMed

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

    2016-06-01

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

  13. Core-Shell in Liquid Chromatography: Application for Determining Sulphonamides in Feed and Meat Using Conventional Chromatographic Systems

    PubMed Central

    Armentano, Antonio; Summa, Simona; Magro, Sonia Lo; D’Antini, Pasquale; Palermo, Carmen; Muscarella, Marilena

    2016-01-01

    A C18 column packed with core-shell particles was used for the chromatographic separation of sulphonamides in feed and meat by a conventional high performance liquid chromatography system coupled with a diode array detector. Two analytical methods, already used in our laboratory, have been modified without any changes in the extraction and clean-up steps and in the liquid chromatography instrumentation. Chromatographic conditions applied on a traditional 5-µm column have been optimized on a column packed with 2.6 µm core-shell particles. A binary mobile phase [acetate buffer solution at pH 4.50 and a mixture of methanol acetonitrile 50: 50 (v/v)] was employed in gradient mode at the flow rate of 1.2 mL with an injection volume of 6 µL. These chromatographic conditions allow the separation of 13 sulphonamides with an entire run of 13 minutes. Preliminary studies have been carried out comparing blanks and spiked samples of feed and meat. A good resolution and the absence of interferences were achieved in chromatograms for both matrices. Since no change was made to the sample preparation, the optimized method does not require a complete revalidation and can be used to make routine analysis faster. PMID:28217560

  14. Spin-Liquid-to-Spin-Liquid Transition in Kitaev Magnets Driven by Fractionalization.

    PubMed

    Nasu, Joji; Kato, Yasuyuki; Yoshitake, Junki; Kamiya, Yoshitomo; Motome, Yukitoshi

    2017-03-31

    While phase transitions between magnetic analogs of the three states of matter-a long-range ordered state, paramagnet, and spin liquid-are extensively studied, the possibility of "liquid-liquid" transitions, namely, between different spin liquids, remains elusive. By introducing the additional Ising coupling into the honeycomb Kitaev model with bond asymmetry, we discover that the Kitaev spin liquid turns into a spin-nematic quantum paramagnet before a magnetic order is established by the Ising coupling. The quantum phase transition between the two liquid states accompanies a topological change driven by fractionalized excitations, the Z_{2} gauge fluxes, and is of first order. At finite temperatures, this yields a persisting first-order transition line that terminates at a critical point located deep inside the regime where quantum spins are fractionalized. It is suggested that similar transitions may occur in other perturbed Kitaev magnets with bond asymmetry.

  15. Estimation of liquid volume fraction using ultrasound transit time spectroscopy

    NASA Astrophysics Data System (ADS)

    Al-Qahtani, Saeed M.; Langton, Christian M.

    2016-12-01

    It has recently been proposed that the propagation of an ultrasound wave through complex structures, consisting of two-materials of differing ultrasound velocity, may be considered as an array of parallel ‘sonic rays’, the transit time of each determined by their relative proportion; being a minimum (t min) in entire higher velocity material, and a maximum (t max) in entire lower velocity material. An ultrasound transit time spectrum (UTTS) describes the proportion of sonic rays at an individual transit time. It has previously been demonstrated that the solid volume fraction of a solid:liquid composite, specifically acrylic step-wedges immersed in water, may be reliably estimated from the UTTS. The aim of this research was to investigate the hypothesis that the volume fraction of a two-component liquid mixture, of unequal ultrasound velocity, may also be estimated by UTTS. A through-transmission technique incorporating two 1 MHz ultrasound transducers within a horizontally-aligned cylindrical tube-housing was utilised, the proportion of silicone oil to water being varied from 0% to 100%. The liquid volume fraction was estimated from the UTTS at each composition, the coefficient of determination (R 2%) being 98.9  ±  0.7%. The analysis incorporated a novel signal amplitude normalisation technique to compensate for absorption within the silicone oil. It is therefore envisaged that the parallel sonic ray concept and the derived UTTS may be further applied to the quantification of liquid mixture composition assessment.

  16. Separation of the fatty acids in menhaden oil as methyl esters with a highly polar ionic liquid gas chromatographic column and identification by time of flight mass spectrometry.

    PubMed

    Fardin-Kia, Ali Reza; Delmonte, Pierluigi; Kramer, John K G; Jahreis, Gerhard; Kuhnt, Katrin; Santercole, Viviana; Rader, Jeanne I

    2013-12-01

    The fatty acids contained in marine oils or products are traditionally analyzed by gas chromatography using capillary columns coated with polyethylene glycol phases. Recent reports indicate that 100 % cyanopropyl siloxane phases should also be used when the analyzed samples contain trans fatty acids. We investigated the separation of the fatty acid methyl esters prepared from menhaden oil using the more polar SLB-IL111 (200 m × 0.25 mm) ionic liquid capillary column and the chromatographic conditions previously optimized for the separation of the complex mixture of fatty acid methyl esters prepared from milk fat. Identifications of fatty acids were achieved by applying Ag(+)-HPLC fractionation and GC-TOF/MS analysis in CI(+) mode with isobutane as the ionization reagent. Calculation of equivalent chain lengths confirmed the assignment of double bond positions. This methodology allowed the identification of 125 fatty acids in menhaden oil, including isoprenoid and furanoid fatty acids, and the novel 7-methyl-6-hexadecenoic and 7-methyl-6-octadecenoic fatty acids. The chromatographic conditions applied in this study showed the potential of separating in a single 90-min analysis, among others, the short chain and trans fatty acids contained in dairy products, and the polyunsaturated fatty acids contained in marine products.

  17. 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.

  18. Using the GELFREE 8100 Fractionation System for molecular weight-based fractionation with liquid phase recovery.

    PubMed

    Witkowski, Chuck; Harkins, Jay

    2009-12-03

    The GELFREE 8100 Fractionation System is a novel protein fractionation system designed to maximize protein recovery during molecular weight based fractionation. The system is comprised of single-use, 8-sample capacity cartridges and a benchtop GELFREE Fractionation Instrument. During separation, a constant voltage is applied between the anode and cathode reservoirs, and each protein mixture is electrophoretically driven from a loading chamber into a specially designed gel column gel. Proteins are concentrated into a tight band in a stacking gel, and separated based on their respective electrophoretic mobilities in a resolving gel. As proteins elute from the column, they are trapped and concentrated in liquid phase in the collection chamber, free of the gel. The instrument is then paused at specific time intervals, and fractions are collected using a pipette. This process is repeated until all desired fractions have been collected. If fewer than 8 samples are run on a cartridge, any unused chambers can be used in subsequent separations. This novel technology facilitates the quick and simple separation of up to 8 complex protein mixtures simultaneously, and offers several advantages when compared to previously available fractionation methods. This system is capable of fractionating up to 1mg of total protein per channel, for a total of 8 mg per cartridge. Intact proteins over a broad mass range are separated on the basis of molecular weight, retaining important physiochemical properties of the analyte. The liquid phase entrapment provides for high recovery while eliminating the need for band or spot cutting, making the fractionation process highly reproducible.

  19. Improved high performance liquid chromatographic determination of ginsenosides in Panax ginseng-based pharmaceuticals using a diol column.

    PubMed

    Bonfill, Mercè; Casals, Isidre; Palazón, Javier; Mallol, Anna; Morales, Carmen

    2002-02-01

    A reversed-phase high-performance liquid chromatographic assay for the simultaneous quantitative determination of seven ginsenosides, Rb(1), Rb(2), Rc, Rd, Rg(1), Re and Rf in pharmaceutical preparations is described. Chromatographic separation was achieved in less than 20 min using a 250 x 4 mm Lichrospher, 5 microm, 100 A diol column with detection at 203 nm. The method was validated over the range of 2.5-20 ng/microL using a 20 microL sample volume. The average accuracy at five concentrations was 90-100%, and the within-day and between-day precision ranged from 1 to 7% expressed as coefficient of variation. The detection limit and the quantitation limit of the method were 20 and 50 ng injected for each ginsenoside, respectively. Copyright 2002 John Wiley & Sons, Ltd.

  20. High-performance liquid chromatographic method for assay of otilonium bromide, diazepam, and related compounds in finished pharmaceutical forms.

    PubMed

    Mannucci, C; Bertini, J; Cocchini, A; Perico, A; Salvagnini, F; Triolo, A

    1993-04-01

    A rapid, simple, stability-indicating assay procedure for otilonium bromide, a smooth muscle relaxant agent, and diazepam in composite tablet analysis was developed with high-performance liquid chromatography. The tablet matrix was dissolved with water, and drugs were extracted with acetonitrile containing an internal standard. An aliquot was centrifuged and chromatographed on a 5-microns, reversed-phase column with 0.5 M sodium acetate trihydrate buffer containing 5 mM 1-heptanesulfonic acid monohydrate sodium salt:methanol (30:70; v/v; adjusted to pH 6.0 with glacial acetic acid) as the mobile phase. The selectivity of the chromatographic system was demonstrated by resolving both compounds from various potential degradation products of each compound. The method is linear, quantitative, and reproducible.

  1. High-performance liquid chromatographic analysis of glucuronic acid conjugates after derivatization with 4-bromomethyl-7-methoxycoumarin.

    PubMed

    Chakir, S; Leroy, P; Nicolas, A; Ziegler, J M; Labory, P

    1987-06-12

    In order to enhance the detection sensitivity of various glucuronic acid conjugates (phenol, menthol borneol, estrone and testosterone) in high-performance liquid chromatography (HPLC), the compounds were esterified with 4-bromomethyl-7-methoxycoumarin in the presence of potassium carbonate and 18-crown-6 in acetone. The resulting esters were chromatographed on either a normal-phase (NP) column (LiChrospher DIOL) with hexane-ethanol mixtures as eluents or a reversed-phase column (LiChrospher CH-18) with methanol-water mixtures. They were detected by UV spectrophotometry at 328 nm. The structure of the derivatives was confirmed by mass spectrometry by direct introduction and chemical ionization. Prior to this step, their isolation on a semi-preparative scale was performed by NP-HPLC. The extraction of the studied glucuronides from microsomal solutions was tested by ion-suppression and ion-pair liquid-liquid partition and liquid-solid chromatography (on octadecylsilica cartridges). Extraction and chromatographic data are discussed with regard to the determination of glucuronyltransferase activity towards the aglycones cited above.

  2. Dispersive liquid-liquid microextraction for the high performance liquid chromatographic determination of aldehydes in cigarette smoke and injectable formulations.

    PubMed

    Ahad Bavili Tabrizi; Abdollahi, Ali

    2013-06-15

    A dispersive liquid-liquid microextraction method (DLLME) combined with high performance liquid chromatography (HPLC) was developed for the extraction and determination of some aldehydes, such as benzaldehyde (BzA), butyraldehyde (BuA) and furfural (Fur) in mainstream cigarette smoke as well as BzA in injectable formulations. After trapping of combustion smoke into sulfuric acid with a laboratory-made smoking machine, aldehydes were converted into their hydrazone derivatives by the reaction with 2,4-dinitrophenylhydrazine (DNPH), and then rapidly extracted by DLLME. The effects of various experimental parameters on the derivatization and extraction were studied and optimized. Under the optimum extraction conditions, linear calibration curves in the range 0.025 to 1.0 μg/mL with correlation coefficients of 0.9980-0.9996 were obtained for studied aldehydes. Limit of detections (LODs) for BzA, BuA and Fur were found to be 14.2, 21.3 and 7.92 μg/L, respectively. The relative standard deviations (RSDs) for inter-and intra-day assays were lower than 8.50%. Average recoveries for spiked samples were in the range 88.0-109%. The proposed method was successfully applied to the determination of aldehydes in different real samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Hyphenated liquid chromatographic method for the determination of colistin residues in bovine tissues.

    PubMed

    Decolin, D; Leroy, P; Nicolas, A; Archimbault, P

    1997-12-01

    A selective and sensitive high-performance liquid chromatographic (HPLC) method has been developed for the measurement of colistin residues in milk and in four bovine tissues (i.e., muscle, liver, kidney, and fat). The sample treatment consists of protein precipitation using 10% (w/v) trichloroacetic acid, solid-phase purification on C18 cartridges, and precolumn derivatization of colistin with ortho-phthalaldehyde and 2-mercaptoethanol in borate buffer (pH 10.5). This latter step is performed automatically, and the resulting reaction mixture is injected into a switching HPLC system including a precolumn and an analytical column packed with end-capped LiChrospher RP18 (5 microns). Washing the precolumn and final elution onto the analytical column are conducted using acetonitrile-0.01M phosphate buffer (pH 7.0) mixtures with respective proportions of 65:35 and 68:32 (v/v). Detection is carried out by spectrofluorometry (excitation wavelength, 340 nm; emission wavelength, 440 nm). The retention times of the derivatives corresponding to the two main components of colistin (i.e., polymyxins E2 and E1) are approximately 14 and 18 min, respectively. The structural study of the derivatives corresponding to polymyxins E1 and E2 is carried out by HPLC coupled with electrospray mass spectrometry; data obtained confirms that the derivatization process occurs with the five amino groups of the analytes. Selectivity is obtained in the HPLC system versus other coadministered anti-infective drugs (beta-lactams, aminoglycosides, tetracyclines, and sulphonamides) and endogenous compounds. Quantitation is performed using the sum of the peak areas of polymyxin E1 and polymyxin E2 derivatives. Testing linearity affords correlation coefficients greater than 0.990 for calibration curves in the range of 10-500 microL/L for milk, 50-1000 micrograms/kg for muscle and fat, and 100-1000 micrograms/kg for kidney and liver. Relative standard deviation values are less than 10% at a concentration

  4. Evaluation of traditional Chinese herbal medicine: Chaihu (Bupleuri Radix) by both high-performance liquid chromatographic and high-performance thin-layer chromatographic fingerprint and chemometric analysis.

    PubMed

    Tian, Run-tao; Xie, Pei-shan; Liu, He-ping

    2009-03-13

    Chaihu (Bupleuri Radix), roots of Bupleurum chinense and B. scorzonerifolium, is an authentic Chinese Materia Medica in the Chinese Pharmacopoeia. Some other species such as the roots of B. falcatum, B.bicaule and B. marginatum var. stenophyllum similar to Chaihu can also be occasionally found in local raw herb markets. The quality of 33 lots of authenticated Chaihu samples vs. 31 lots of commercial samples was evaluated by both high-performance liquid chromatography-evaporative light scattering detector (HPLC-ELSD) and high-performance thin-layer chromatography (HPTLC) analyses of its principal bioactive components (saikosaponins). The pre-treated data acquired from both HPLC fingerprints and HPTLC fluorescent images were processed by chemometrics for similarity and pattern recognition, including Artificial Neural Networks (ANNs), k-nearest neighbor (k-NN) and an expert's panel. It was apparent that k-NN classifier exhibited good performance with sufficient flexibility for processing HPTLC fingerprint images which were otherwise not easily dealt with by other algorithms due to the shift of R(f) values and varying hue/saturation of the band colours between different TLC plates. These two chromatographic fingerprint methods can be considered complementary measure of quality control. The roots of Chaihu from different species of the genus Bupleurum could readily be distinguished from each other so that commercial samples can easily be classified. Chaihu collected from several major herbal distribution centers was found to belong to B. chinense with great variation in the content of its major saikosaponins.

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

    PubMed

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

    2015-01-01

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

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

    PubMed

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

    1999-01-01

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

  7. [Effect of high performance liquid chromatographic instrument system on the analysis of erythromycin A oxime].

    PubMed

    Sun, Jing-gu; Yao, Guo-wei; Ou, Yu-xiang

    2004-09-01

    A HPLC chromatography for the determination of erythromycin A oxime and relative compounds was studied, and the effect of chromatography systems including a HITACHI L-7100, a Shimadzu LC-6A, a Waters 474 and relative columns was analyzed. It was revealed that different HPLC apparatus and columns have obvious impact on the peak separation and retention time under the general chromatographic condition. The suitable chromatographic conditions for several different chromatography systems were summarized with good linear relationship, which is very significant to the quality control of erythromycin A oxime and relative compounds.

  8. High-performance liquid chromatographic determination of benzalkonium and naphazoline or tetrahydrozoline in nasal and ophthalmic solutions.

    PubMed

    Santoni, G; Medica, A; Gratteri, P; Furlanetto, S; Pinzauti, S

    1994-11-01

    A high-performance liquid chromatographic method is described for the determination of benzalkonium chloride homologues and naphazoline nitrate or tetrahydrozoline hydrochloride in ophthalmic and nasal solutions. The technique involves a one-step dilution (1:5) for sample preparation and direct injection onto a 5 mm RP C-8 column. The mobile phase is acetonitrile-diluted acetic acid (80:20, v/v) with 6 mM tetramethylammonium bromide. Detection is carried out at 260 nm with a diode array. The method is rapid, specific, reproducible and is especially useful for quality control procedures.

  9. Liquid chromatographic determination of hippuric acid for the evaluation of ethacrynic acid as angiotensin converting enzyme inhibitor.

    PubMed

    Mehanna, A S; Dowling, M

    1999-05-01

    A rapid, simple and interference-free method is described to evaluate the inhibitory effects of organic compounds on the activity of angiotensin converting enzyme irrespective of their acid-base properties. The assay is based on the high performance liquid chromatographic separation of the synthetic substrate hippuryl-L-histidyl-L-leucine, the hydrolysis product hippuric acid and the test compound. Using the new method, the diuretic drug ethacrynic acid was found to act as an inhibitor for the enzyme in a non competitive mode.

  10. High-performance liquid chromatographic method for the determination of salicylic acid and its metabolites in urine by direct injection.

    PubMed

    Mallikaarjun, S; Wood, J H; Karnes, H T

    1989-08-25

    A direct injection method has been developed for the determination of salicylic acid and its metabolites in urine. Urine samples are treated with hydroxylamine to convert salicyl acyl glucuronide to salicylhydroxamic acid, which can be accurately quantitated by direct injection into a high-performance liquid chromatographic system along with salicylic acid, gentisic acid and salicyluric acid. Salicyl phenolic glucuronide is quantitated by difference after hydrochloric acid hydrolysis at 65 degrees C with no loss of salicylic acid by sublimation or hydrolytic loss of salicyluric acid. This method has been applied to urine samples from human subjects and the results are discussed.

  11. 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.

  12. Moving from fast to ballistic gradient in liquid chromatography/tandem mass spectrometry pharmaceutical bioanalysis: Matrix effect and chromatographic evaluations.

    PubMed

    De Nardi, Claudio; Bonelli, Fabio

    2006-01-01

    The paper describes the steps taken by the authors to move from a fast to a ballistic gradient in routine liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis of plasma samples from pharmacokinetic (PK) profiling of new chemical entities. The reduction of column dimensions from 50 x 4.6 mm to 30 x 2.1 mm followed by optimization of chromatographic separation led to a decrease in the typical runtime from 5 (fast) to 2 min (ballistic) using an API4000 tandem mass spectrometer in Turbo Ionspray mode for detection. Three analytical standards representing typical molecular structures from our sample repository were used to spike plasma from four different species (rat, dog, human and mouse). Two different approaches were used to evaluate matrix effect: post-column infusion and comparison of the peak areas of neat standards and standards spiked after extraction into different pools of plasma; the influence of PEG400 as a typical dosing vehicle was also considered. Two different protein precipitation procedures were taken into account for sample extraction prior to injection. Peak shape, width and height, selectivity and sensitivity of the method were taken into account for chromatographic evaluation. The ballistic method was successfully cross-validated with the conventional fast gradient chromatographic assay.

  13. 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.

  14. Liquid chromatographic properties of aromatic sulfur heterocycles on a Pd(II)-containing stationary phase for petroleum analysis.

    PubMed

    Sripada, Kishore; Andersson, Jan T

    2005-06-01

    Polycyclic aromatic sulfur heterocycles (PASHs) can show very poor reactivities in catalytic hydrodesulfurization processes in refineries, especially those in high-boiling fractions and distillation residues. An insight into the structural features of the most recalcitrant PASHs is essential for developing more efficient catalysts and improving refinery processes. The very high complexities of such mixtures necessitate fractionation of the samples into smaller subsets according to defined criteria. A stationary phase containing a palladium(II)-complex was previously shown to be efficient for separating PASHs in lighter petroleum fractions. Here we characterize this ligand exchange chromatographic phase using a large number of sulfur aromatic model compounds that were synthesized for the purpose. In general, compounds containing thiophene rings that are not condensed with other aromatic systems are weakly retained and elute in a first fraction with the polycyclic aromatic hydrocarbons. Thiophene rings condensed with other aromatic rings are more strongly retained and elute in a later fraction with a more polar eluent. If the sulfur is in a non-aromatic ring, the compound is irreversibly retained by the Pd(II) ions. Some steric effects are seen in compounds with alkyl or aryl substituents close to the sulfur atom but in general they do not interfere strongly with the complexation. Thus it seems possible to separate groups of aromatic sulfur compounds according to their complexation properties. For instance, such fractionated samples can be studied much more easily by mass spectrometric techniques.

  15. 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.

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

    PubMed

    Punwar, J K

    1975-07-01

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

  17. Rapid and sensitive high-performance liquid chromatographic determination of nicotine and cotinine in nonsmoker human and rat urines.

    PubMed

    Oddoze, C; Pauli, A M; Pastor, J

    1998-04-24

    A simple reversed-phase high-performance liquid chromatographic method with paired-ion and UV detection has been developed for the rapid quantification of urinary nicotine and cotinine. A one-step solid-liquid extraction on Extrelut was used. Separation from endogenous substances was achieved with a decreasing flow-rate. With 20 ml of urine for extraction, the limit of quantification was 0.5 ng/ml for cotinine and 5 ng/ml for nicotine; linearity was obtained from 50 to 5000 ng/ml. The intra- and inter-day coefficients of variation were less than 9% for cotinine and 30% for nicotine. Average recoveries for cotinine were 92-100% and 47-86% for nicotine. The present method was applied to the urine analysis of smokers, nonsmoker children, and experimental animals.

  18. Chromatographic separation of platinum group metals from simulated high level liquid waste using macroporous silica-based adsorbents.

    PubMed

    Xu, Yuanlai; Kim, Seong-Yun; Ito, Tatsuya; Tokuda, Haruki; Hitomi, Keitaro; Ishii, Keizo

    2013-10-18

    To separate platinum group metals (PGMs) from high level liquid waste, three novel macroporous silica-based adsorbents, namely, (Crea+Dodec)/SiO2-P, (Crea+TOA)/SiO2-P and (MOTDGA+TOA)/SiO2-P, were synthesized by introducing extractants Crea (N',N'-di-n-hexyl-thiodiglycolamide), TOA (Tri-n-octylamine), MOTDGA (N,N'-dimethyl-N,N'-di-n-octyl-thiodiglycolamide) along with theirs modifier, Dodec (n-dodecyl alcohol), into 50μm diameter SiO2-P particles by impregnation. Chromatographic separation of PGMs from simulated high level liquid waste was investigated by column method. It was found that 100% of Pd(II) and Re(VII) could be eluted out from simulate HLLW in 3.0M HNO3 solution using three adsorbents. For Ru(III) and Rh(III), high temperature has distinct effect on the adsorption rate and a further study for Ru(III) and Rh(III) is necessary to separate them from HLLW completely. In all six column experiments, a relatively satisfactory chromatographic separation operating for PGMs from simulated HLLW was obtained using (Crea+TOA)/SiO2-P adsorbent packed column at 323K.

  19. Simultaneous liquid chromatographic determination of lamotrigine, oxcarbazepine monohydroxy derivative and felbamate in plasma of patients with epilepsy.

    PubMed

    Contin, Manuela; Balboni, Monica; Callegati, Erica; Candela, Carmina; Albani, Fiorenzo; Riva, Roberto; Baruzzi, Agostino

    2005-12-15

    A very simple and fast method has been developed and validated for simultaneous determination of the new generation antiepileptic drugs (AEDs) lamotrigine (LTG), oxcarbazepine's (OXC) main active metabolite monohydroxycarbamazepine and felbamate in plasma of patients with epilepsy using high-performance liquid chromatography (HPLC) with spectrophotometric detection. Plasma sample (500 microL) pre-treatment was based on simple deproteinization by acetonitrile. Liquid chromatographic analysis was carried out on a Synergi 4 microm Hydro-RP, 150 mm x 4 mm I.D. column, using a mixture of potassium dihydrogen phosphate buffer (50mM, pH 4.5) and acetonitrile/methanol (3/1) (65:35, v/v) as the mobile phase, at a flow rate of 1.0 mL/min. The UV detector was set at 210 nm. Calibration curves were linear (mean correlation coefficient >0.999 for all the three analytes) over a range of 1-20 mg/mL for lamotrigine, 2-40 microg/mL for monohydroxycarbamazepine and 10-120 microg/mL for felbamate. Both intra and interassay precision and accuracy were lower than 7.5% for all three analytes. Absolute recoveries ranged between 100 and 104%. The present procedure describes for the first time the simultaneous determination of these three new antiepileptic drugs. The simple sample pre-treatment, combined with the fast chromatographic run permit rapid processing of a large series of patient samples.

  20. 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.

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

    PubMed

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

    2016-01-01

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

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

    PubMed Central

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

    2016-01-01

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

  3. Fractionalized Fermi liquid in a Kondo-Heisenberg model

    SciTech Connect

    Tsvelik, A. M.

    2016-10-10

    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. Here, I use a nonperturbative approach where the strongest interactions are taken into account by means of exact solution, and corrections are controllable. The resulting metallic state represents a fractionalized Fermi liquid where well defined quasiparticles coexist with gapped fractionalized collective excitations, in agreement with the general requirements formulated by T. Senthil et al. [Phys. Rev. Lett. 90, 216403 (2003)]. Furthermore, 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.

  4. Fractionalized Fermi liquid in a Kondo-Heisenberg model

    DOE PAGES

    Tsvelik, A. M.

    2016-10-10

    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. Here, I use a nonperturbative approach where the strongest interactions are taken into account by means of exact solution, and corrections are controllable. The resulting metallic state represents a fractionalized Fermi liquid where well defined quasiparticles coexist with gapped fractionalized collective excitations, in agreement with the general requirements formulated by T. Senthil et al. [Phys. Rev. Lett. 90, 216403 (2003)]. Furthermore, the system undergoes amore » 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.« less

  5. Fractionalized Fermi liquid in a Kondo-Heisenberg model

    SciTech Connect

    Tsvelik, A. M.

    2016-10-10

    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. Here, I use a nonperturbative approach where the strongest interactions are taken into account by means of exact solution, and corrections are controllable. The resulting metallic state represents a fractionalized Fermi liquid where well defined quasiparticles coexist with gapped fractionalized collective excitations, in agreement with the general requirements formulated by T. Senthil et al. [Phys. Rev. Lett. 90, 216403 (2003)]. Furthermore, 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.

  6. A systematic approach for the chromatographic fractionation and purification of major steroid saponins in commercial extracts of Yucca schidigera Roezl.

    PubMed

    Sastre, F; Ferreira, F; Pedreschi, F

    2017-03-01

    Yucca schidigera Roezl. (yucca) is one of the major industrial sources of steroid saponins used as animal and human food additives. This work describes a new, systematic and reproducible three-step method by medium and high-pressure liquid chromatography (under RP, NP and RP conditions), for the isolation and purification of three groups of saponins, which were further purified in six sub-fractions, and finally into twelve individual steroid saponins previously reported in Y. schidigera. In accordance to the increasing applications of yucca extracts, further analytical, biological and physicochemical studies are still required. The presented method is applicable to the preparation of steroids saponins previously reported in commercial extracts of Y. schidigera, both as highly purified mixtures of defined composition, including twelve pure components.

  7. 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

  8. 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

  9. Detecting spin fractionalization in a spinon Fermi surface spin liquid

    NASA Astrophysics Data System (ADS)

    Li, Yao-Dong; Chen, Gang

    2017-08-01

    Motivated by the recent proposal that several candidate materials such as YbMgGaO4 could be spinon Fermi surface spin liquids, we explore the experimental consequences of the external magnetic fields on this exotic state. Specifically, we focus on the weak field regime where the spin-liquid state is well preserved and the spinon remains to be a good description of the magnetic excitations. From the spin-1/2 nature of the spinon excitation, we predict the unique features of the spinon continuum when the weak magnetic field is applied to the system. Due to the small energy scale of the exchange interactions between the local moments in the spin-liquid candidate like YbMgGaO4, our proposal for the spectral weight shifts and spectral crossing in the magnetic fields can be immediately tested by inelastic neutron scattering experiments. Several other experimental aspects about the spinon Fermi surface and the spinon excitations are discussed and proposed. Our work provides an experimental scheme to examine the fractionalized spinon excitation and the candidate spin-liquid states in YbMgGaO4, the 6H-B phase of Ba3NiSb2O9 , and other relevant materials.

  10. 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.

  11. Optimization and Assessment of Three Different High Performance Liquid Chromatographic Systems for the Combinative Fingerprint Analysis and Multi-Ingredients Quantification of Sangju Ganmao Tablet.

    PubMed

    Guo, Meng-Zhe; Han, Jie; He, Dan-Dan; Zou, Jia-Hui; Li, Zheng; Du, Yan; Tang, Dao-Quan

    2017-03-01

    Chromatographic separation is still a critical subject for the quality control of traditional Chinese medicine. In this study, three different high performance liquid chromatographic (HPLC) systems employing commercially available columns packed with 1.8, 3.5 and 5.0 μm particles were respectively developed and optimized for the combinative fingerprint analysis and multi-ingredients quantification of Sangju Ganmao tablet (SGT). Chromatographic parameters including the repeatability of retention time and peak area, symmetry factor, resolution, number of theoretical plates and peak capacity were used to assess the chromatographic performance of different HPLC systems. The optimal chromatographic system using Agilent ZORBAX SB-C18 column (2.1 mm × 100 mm, 3.5 μm) as stationary phase was respectively coupled with diode array detector or mass spectrometry detector for the chromatographic fingerprint analysis and simultaneous quantification or identification of nine compounds of SGT. All the validation data conformed to the acceptable requirements. For the fingerprint analysis, 31 peaks were selected as the common peaks to evaluate the similarities of SGT from 10 different manufacturers using heatmap, hierarchical cluster analysis and principal component analysis. The results demonstrated that the combinations of the quantitative and chromatographic fingerprint analysis offer an efficient way to evaluate the quality consistency of SGT.

  12. Liquid Chromatographic Determination of Explosives and Polynuclear Aromatic Hydrocarbons (PAHs) in Deactivation Furnace Ash.

    DTIC Science & Technology

    1986-08-01

    High performance liquid chromatography (HPLC) Polynuclear aromatic hydrocarbons (PAHs...chromatography or high performance liquid chromatography (HPLC). Gas chromatography (GC), because of its speed and sensitivity, has received much...Staley. 1976. Determination of polycyclic aromatic hydrocarbons in atmospheric particulate matter by high performance liquid chromatography coupled

  13. 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

    2016-01-08

    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. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. A validated stability-indicating liquid chromatographic method for the determination of retapamulin in topical dosage form.

    PubMed

    Nalwade, Santaji; Reddy, Vangala Ranga

    2014-03-01

    A sensitive, stability-indicating reversed-phase high-performance liquid chromatographic method is developed and validated for the quantitative determination of retapamulin in topical dosage form. The chromatographic separation is achieved by using a C18 column (XTerra RP 18 250 × 4.6 mm, 5 µm) at 30°C. The mobile phase comprises a mixture of 0.05M potassium dihydrogen phosphate buffer (pH 6.1), acetonitrile and methanol in the ratio of 35:50:15 (v/v/v). The flow rate is set at 1.0 mL/min and chromatograms are extracted at 243 nm using a photodiode array detector. The method is validated with respect to linearity, accuracy, precision, robustness and forced degradation studies, which further prove the stability-indicating supremacy of the method. During forced degradation studies, retapamulin is observed to be labile to oxidative and base hydrolysis stress and stable in thermal, photolytic and acid hydrolysis stress. The degradation products are well separated from the retapamulin peak, thus proving the stability-indicating superiority of the method. The method is found to be sensitive for retapamulin, with a detection limit of 25 ng/mL and a quantification limit of 80 ng/mL. The proposed method is found to be very sensitive and accurate for the determination of retapamulin in topical dosage form. The method is also demonstrated to be robust, because it is resistant to small variations of chromatographic variables such as pH, mobile phase composition, flow rate and column temperature.

  15. How to compare separation selectivity of high-performance liquid chromatographic columns properly?

    PubMed

    Andrić, Filip; Héberger, Károly

    2017-03-10

    Comparison and selection of chromatographic columns is an important part of development as well as validation of analytical methods. Presently there is abundant number of methods for selection of the most similar and orthogonal columns, based on the application of limited number of test compounds as well as quantitative structure retention relationship models (QSRR), from among Snyder's hydrophobic-subtraction model (HSM) have been most extensively used. Chromatographic data of 67 compounds were evaluated using principal component analysis (PCA), hierarchical cluster analysis (HCA), non-parametric ranking methods as sum of ranking differences (SRD) and generalized pairwise correlation method (GPCM), both applied as a consensus driven comparison, and complemented by the comparison with one variable at a time (COVAT) approach. The aim was to compare the ability of the HSM approach and the approach based on primary retention data of test solutes (logk values) to differentiate among ten highly similar C18 columns. The ranking (clustering) pattern of chromatographic columns based on primary retention data and HSM parameters gave different results in all instances. Patterns based on retention coefficients were in accordance with expectations based on columns' physicochemical parameters, while HSM parameters provided a different clustering. Similarity indices calculated from the following dissimilarity measures: SRD, GPCM Fisher's conditional exact probability weighted (CEPW) scores; Euclidian, Manhattan, Chebyshev, and cosine distances; Pearson's, Spearman's, and Kendall's, correlation coefficients have been ranked by the consensus based SRD. Analysis of variance confirmed that the HSM model produced statistically significant increases of SRD values for the majority of similarity indices, i.e. HS transformation of original retention data yields significant loss of information, and finally results in lower performance of HSM methodology. The best similarity measures were

  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. A high-performance liquid chromatographic method for determination of scopolin in rat plasma: application to pharmacokinetic studies.

    PubMed

    Xia, Yu-Feng; Dai, Yue; Wang, Qiang; Cai, Fei

    2008-10-01

    An analytical method based on high-performance liquid chromatographic (HPLC) with ultraviolet (UV) detection was developed for determination of scopolin in rat plasma using aesculin as internal standard (IS). After protein precipitation of plasma sample with methanol, the supernatant was directly injected and analyzed. Chromatographic separation was achieved on a C18 column using methanol and distilled water (22:78, v/v) containing 0.2% (v/v) glacial acetic acid as mobile phase with a column temperature of 30 degrees C. The UV detector was set at 338 nm. The calibration curve was linear over the range of 0.105-13.125 microg/mL with a correlation coefficient of 0.9998. The retention times of aesculin and scopolin were 10.4 and 12.8 min, respectively. The recoveries for plasma samples of 0.105, 4.725 and 13.125 microg/mL were 91.08, 95.30 and 96.10%, respectively. The RSD of intra- and inter-day assay variations was less than 7.35%. The lower limit of detection was 0.03 microg/mL .This HPLC assay is a simple, sensitive and accurate and was successfully applied to the pharmacokinetic study of scopolin in rats.

  18. Liquid Chromatographic-Chemometric Techniques for the Simultaneous HPLC Determination of Lansoprazole, Amoxicillin and Clarithromycin in Commercial Preparation.

    PubMed

    Aktas, A Hakan; Saridag, Ayse Mine

    2017-09-01

    Two multivariate calibration-prediction techniques, principal component regression (PCR) and partial least-squares regression (PLSR) were applied to the chromatographic multicomponent analysis of the drug containing lansoprazole (LAN), clarithromycin (CLA) and amoxicillin (AMO). Optimum chromatographic separation of LAN, CLA and AMO with atorvastatin as the internal standard (IS) was obtained by using Xterra® RP18 column 5 μm 4.6 × 250 mm2, and 25 mM ammonium chloride buffer prepared ammonium chloride, acetonitrile and bidistilled water (45:45:10 v/v) as the mobile phase at flow rate 1.0 mL/min. The high pressure liquid chromatography data sets consisting of the ratios of analyte peak areas to the IS peak area were obtained by using diode array detector detection at five wavelengths (205, 210, 215, 220 and 225 nm). LC-chemometric calibration for LAN, CLA and AMO were separately constructed by using the relationship between the peak-area ratio and training sets for each analyte. A series of synthetic solutions containing different concentrations of LAN, CLA and AMO were used to check the prediction ability of the PCR and PLS. Both of the two-chemometric methods in this study can be satisfactorily used for the quantitative analysis and for dissolutions tests of multicomponent commercial drug. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. Development and validation of a liquid chromatographic method for the determination of ascorbic acid, dehydroascorbic acid and acetaminophen in pharmaceuticals.

    PubMed

    Gioia, M G; Andreatta, P; Boschetti, S; Gatti, R

    2008-09-29

    A reversed-phase ion pair liquid chromatographic method (RP-LC) for the determination of dehydroascorbic acid (DHA) and ascorbic acid (AA) and also acetaminophen, which is combined in pharmaceuticals, is proposed and validated. AA and acetaminophen were analyzed directly, while DHA was determined after pre-column derivatization with 4,5-dimethyl-1,2-phenylenediamine (DMPD). The derivatization reaction was carried out under mild conditions (10min at ambient temperature) in the dark in sodium acetate buffer (80mM; pH 3.7) solution containing EDTA as metal scavenger. The chromatographic separations were performed on a Phenomenex Synergi 4u hydro-RP (150mmx4.6mm) under isocratic elution conditions, using cetyltrimethylammonium bromide (CTAB) as ion-pairing reagent in the mobile phase. Linear responses were observed for each compound. The intra-day precision (R.S.D.) was < or =1.40% and there was no significant difference between intra- and inter-day data. Recovery studies showed good results for all compounds (99.7-101.8%) with R.S.D. ranging from 0.56 to 1.82%. The limits of quantitation were about 40, 50 and 140pmol for acetaminophen, AA and DHA, respectively. The DHA impurity values found in dosage forms were < or =0.2% of AA.

  20. Chromatographic fingerprinting analysis of Zhizhu Wan preparation by high-performance liquid chromatography coupled with photodiode array detector.

    PubMed

    Sun, Hui; Chen, Xi; Zhang, Aihua; Sakurai, Tetsuro; Jiang, Jinzhong; Wang, Xijun

    2014-10-01

    Traditional Chinese medicine (TCM) formula has been used for over 1000 years and most of them contain complicate chemical constituents. Chromatographic fingerprinting has been widely accepted as a crucial method for qualitative and quantitative analyses for TCM. Zhi Zhu Wan (ZZW), a classical Chinese medical formula, has been commonly used for the treatment of gastrointestinal disease, which pose a serious challenge to its quality control. In this work, a sensitive and reliable method of high-performance liquid chromatography coupled with photodiode array detector (HPLC-PDA) was developed to control the quality of ZZW for chemical fingerprint analysis and quantitative analysis of four major bioactive constituents, including hesperidin, naringin, neohesperidin, and atractylenolide I. The chromatographic separation was performed on a Waters Symmetry C18 column (4.6 mm × 250 mm, 5 μm particle size), with an aqueous 0.095% phosphate acid and acetonitrile mobile phase gradient. Optimization of other experimental conditions was validated with satisfactory accuracy, precision, repeatability, and recovery. In quantitative analysis, the four components showed good regression (R > 0.9994) within test ranges, and the recovery method ranged from 99.32% to 100.630%. HPLC fingerprints of the ZZW samples were compared by performing similarity analysis. The results indicated that the newly developed HPLC-PDA fingerprint method would be suitable for quality control of ZZW.

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

    PubMed

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

    2012-07-15

    A reversed phase liquid chromatographic-tandem mass spectrometric method with simple solvent extraction and purification by solid phase extraction (SPE) has been developed for the determination of coccidiostats in milk. For sample preparation matrix solid phase dispersion, extraction by organic solvent and SPE with different cartridges were also tested. The compounds determined include lasalocid, narasin, salinomycin, monensin, semduramicin, maduramicin, robenidine, decoquinate, halofuginone, nicarbazin and diclazuril. Main steps of the method are addition of acetonitrile to the milk samples, centrifugation, removal of matrix by SPE, concentration by evaporation and LC-MS-MS determination. During a 15 min time segmented chromatographic run compounds are ionised either positively or negatively. Calculated recoveries range between 77.1% and 118.2%. Maximum levels are in the range of 1-20 μg/kg. The developed method was validated in line with the requirements of Commission Decision 2002/657/EC (2002). It is applicable for control of coccidiostat residues in milk as indicated in Regulation 124/2009/EC (2009). Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. 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.

  3. 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.

  4. Continuous transitions between composite Fermi liquid and Landau Fermi liquid: A route to fractionalized Mott insulators

    NASA Astrophysics Data System (ADS)

    Barkeshli, Maissam; McGreevy, John

    2012-08-01

    One of the most successful theories of a non-Fermi-liquid metallic state is the composite Fermi-liquid (CFL) theory of the half-filled Landau level. In this paper, we study continuous quantum phase transitions out of the CFL state and into a Landau Fermi liquid, in the limit of no disorder and fixed particle number. This transition can be induced by tuning the bandwidth of the Landau level relative to the interaction energy, for instance through an externally applied periodic potential. We find a transition to the Landau Fermi liquid through a gapless Mott insulator with a Fermi surface of neutral fermionic excitations. In the presence of spatial symmetries, we also find a direct continuous transition between the CFL and the Landau Fermi liquid. The transitions have a number of characteristic observable signatures, including the presence of two crossover temperature scales, resistivity jumps, and vanishing compressibility. When the composite fermions are paired instead, our results imply quantum critical points between various non-Abelian topological states, including the ν=1/2 Moore-Read Pfaffian [Ising × U(1) topological order], a version of the Kitaev B phase (Ising topological order), and paired electronic superconductors. To study such transitions, we use a projective construction of the CFL, which goes beyond the conventional framework of flux attachment to include a broader set of quantum fluctuations. These considerations suggest a possible route to fractionalized Mott insulators by starting with fractional quantum Hall states and tuning the Landau-level bandwidth.

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

    PubMed

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

    2001-11-01

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

  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. Liquid chromatographic enantiomer separation of 1-naphthylamides of chiral acids using several amylose- and cellulose-derived chiral stationary phases.

    PubMed

    Islam, Md F; Adhikari, Suraj; Paik, Man-Jeong; Lee, Wonjae

    2017-03-01

    The liquid chromatographic enantiomer separation of various chiral acids as 1-naphthylamides was performed using several chiral stationary phases (CSPs). The CSPs used in this study were six covalently bonded and four coated type CSPs derived from amylose and cellulose derivatives as chiral selectors. The degree of enantioseparation is affected by the structure of chiral acids and the CSPs used, which have different chiral selectors and types of immobilization. For the enantiomer resolution of chiral acids as 1-naphthylamide derivatives, the performance of the coated type Lux Cellulose-1 was superior to those of the other CSPs, except for 2-aryloxypropionic acid derivatives. Owing to the strong ultraviolet absorbance of the 1-naphthyl group, the convenient analytical method developed and validated in this study could be expected to be very useful for the enantiomer separation of various chiral acids as 1-naphthylamide derivatives using polysaccharide-derived CSPs.

  8. Development of liquid chromatographic methods for the determination of phytosterols in Standard Reference Materials containing saw palmetto.

    PubMed

    Bedner, Mary; Schantz, Michele M; Sander, Lane C; Sharpless, Katherine E

    2008-05-23

    Liquid chromatographic (LC) methods using atmospheric pressure chemical ionization/mass spectrometric (APCI-MS) detection were developed for the separation and analysis of the phytosterols campesterol, cycloartenol, lupenone, lupeol, beta-sitosterol, and stigmasterol. Brassicasterol and cholesterol were also included for investigation as internal standards. The methods were used to identify and quantify the phytosterols in each of two Serenoa repens (saw palmetto) Standard Reference Materials (SRMs) developed by the National Institute of Standards and Technology (NIST). Values obtained by LC-MS were compared to those obtained using the more traditional approach of gas chromatography with flame ionization detection. This is the first reported use of LC-MS to determine phytosterols in saw palmetto dietary supplement materials.

  9. Chiral high-performance liquid chromatographic studies of 2-(4-chloro-2-methylphenoxy)propanoic acid.

    PubMed

    Blessington, B; Crabb, N; O'Sullivan, J

    1987-06-19

    The direct enantiomeric resolution of the racemic herbicide 2-(4-chloro-2-methylphenoxy)propanoic acid (CMPP) was demonstrated on an Enantiopac (alpha 1-acid glycoprotein) chiral high-performance liquid chromatographic (HPLC) column. The HPLC separation of various amide derivatives of CMPP on a chiral "Ionic Pirkle" column comprising of N-(3,5-dinitrobenzoyl) (R)-(-)phenylglycine as chiral ligand, was also accomplished. These amides and racemic ibuprofen, however could not be separated on the Enantiopac system. The performance, stability and cost of the two systems were compared. Using optically pure CMPP enantiomers the elution order was determined and shown to reverse between the two systems. It was also shown that negligible racemisation occurred during derivatization.

  10. Design of chiral monochloro-s-triazine reagents for the liquid chromatographic separation of amino acid enantiomers.

    PubMed

    Brückner, H; Wachsmann, M

    2003-05-23

    A series of chiral derivatizing reagents (CDRs) was synthesized by nucleophilic replacement of one chlorine atom in cyanuric chloride (2,4,6-trichloro-1,3,5-triazine; s-triazine) by alkoxy (methoxy, butoxy, 1,1,1-trifluoroethoxy) or aryloxy groups (phenoxy, nitrophenoxy, phenylphenoxy, 4-methylcoumaryloxy), and displacement of a second chlorine by L-alanine amide, L-phenylalanine amide, L-proline tert.-butyl ester, or Boc-L-lysine tert.-butyl ester. Further, CDRs were investigated in which two chlorine atoms in cyanuric chloride were substituted consecutively by L-valine amide and L-phenylalanine amide. The resulting CDRs having a remaining reactive chlorine were tested for their capability of derivatizing DL-amino acids followed by liquid chromatographic separation of the resulting diastereomers.

  11. 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.

  12. Automated stability-indicating high-performance liquid chromatographic assay for ethinyl estradiol and (levo)norgestrel tablets.

    PubMed

    Reif, V D; Eickhoff, W M; Jackman, J K; DeAngelis, N J

    1987-02-01

    An automated high-performance liquid chromatography (HPLC) assay for ethinyl estradiol and norgestrel or levonorgestrel in oral contraceptive tablets was developed. Tablets were prepared for on-line injection using a solid sampler and segmented continuous flow techniques. The active components were separated from tablet excipients, impurities, and degradation products on reversed-phase C8 and C18 columns by elution with water-acetonitrile-methanol (45:35:15). A UV detector connected in series with a fluorometric detector measured the UV absorbance of levonorgestrel and norgestrel at 240 nm and the fluorescence of ethinyl estradiol at 310 nm (excitation at 210 nm). The method employed computer control of the injection system and solid sampler for synchronization of the chromatographic and segmented flow streams. The method is applicable for content uniformity and stability testing at a rate of eight samples per hour.

  13. A high-performance liquid chromatographic (HPLC) method for the simultaneous determination of nitrite and formaldehyde from foods.

    PubMed

    Csiba, A; Szentgyörgyi, M; Juhász, S; Lombai, G

    1996-01-01

    A high-performance liquid chromatographic (HPLC) procedure with fluorometric detector has been developed for the determination of nitrite and formaldehyde from foods by the use of hydralazine. Hydralazine reacts with nitrite and formaldehyde under acidic conditions in boiling water-bath for 15 min to form tetrazolo-(5,1-a)-phthalazine (Tetra-P) and triazolo-(3,4-a)-phthalazine (Tri-P) quantitatively. Without extraction, the determination of Tetra-P and Tri-P was simple, specific, sensitive and reliable over the range of 0.003-0.3 ppm of sodium nitrite and 0.02-0.4 ppm of formaldehyde. This procedure using hydralazine is one of the most useful methods for routine analysis of nitrite and formaldehyde in foods, biological fluids and ambient waters.

  14. Development and validation of a new high-performance liquid chromatographic method for the loperamid hydrochloride determination in drugs

    NASA Astrophysics Data System (ADS)

    Nikolić, G. S.; Savić, I.; Marinković, V.

    2009-09-01

    A selective, precise and new high-performance liquid chromatographic method for the analysis of loperamid hydrochloride in pharmaceutical formulations was developed and validated. The mobile phase consisting buffer (sodium-octansulphonate, triethylamine and ammonium hydroxide) in water: acetonitriie (45: 55, v/v) (pH 3.2). The absorbance was monitored with a DAD detector at 226 nm. The flow rate was 1.5 cm3 min-1. The linearity ( r = 0.9947) and the recovery (98.58-100.42%) were found to be satisfactory. The detection and quantitation limits were found to be 0.95 and 3.12 μg cm-3. The results demonstrated that the procedure was accurate, precise and reproducible. It can be suitably applied for the estimation of lopera-mid hydrochloride in pharmaceutical formulations.

  15. Development of ultra fast liquid chromatographic method for simultaneous determination of nitrendipine and carvone in skin diffusate samples.

    PubMed

    Gannu, Ramesh; Yamsani, Vamshi Vishnu; Yamsani, Shravan Kumar; Palem, Chinna Reddy; Voruganti, Swathi; Yamsani, Madhusudan Rao

    2009-12-05

    A simple and sensitive reverse phase ultra fast liquid chromatographic (UFLC) method for simultaneous determination of nitrendipine and carvone in skin diffusate samples and microemulsions was developed and validated. The separation was achieved using a gradient mobile phase, on an Onyx column. The eluents were monitored by photodiode array detection. The linearity ranges of proposed method were 0.125-50 microg mL(-1) and 0.125-30 microg mL(-1) for nitrendipine and carvone respectively. The intra-day and inter-day coefficient of variation and percent error values of the assay method were less than 10%. The method was found to be precise, accurate, and specific during the study. The method was successfully applied for simultaneous estimation of nitrendipine and carvone in ex vivo skin diffusate samples and microemulsions.

  16. Rapid ion-pair liquid chromatographic method for the determination of fenbendazole marker residue in fermented dairy products.

    PubMed

    Vousdouka, Venetia I; Papapanagiotou, Elias P; Angelidis, Apostolos S; Fletouris, Dimitrios J

    2017-04-15

    A simple, rapid and sensitive liquid chromatographic method that allows for the quantitative determination of fenbendazole residues in fermented dairy products is described. Samples were extracted with a mixture of acetonitrile-phosphoric acid and the extracts were defatted with hexane to be further partitioned into ethyl acetate. The organic layer was evaporated to dryness and the residue was reconstituted in mobile phase. Separation of fenbendazole and its sulphoxide, sulphone, and p-hydroxylated metabolites was carried out isocratically with a mobile phase containing both positively and negatively charged pairing ions. Overall recoveries ranged from 79.8 to 88.8%, while precision data, based on within and between days variations, suggested an overall relative standard deviation of 6.3-11.0%. The detection and quantification limits were lower than 9 and 21μg/kg, respectively. The method has been successfully applied to quantitate fenbendazole residues in Feta cheese and yoghurt made from spiked and incurred ovine milk.

  17. Isotope Fractionation by Diffusion in Liquids (Final Technical Report)

    SciTech Connect

    Richter, Frank

    2016-11-09

    The overall objective of the DOE-funded research by grant DE-FG02-01ER15254 was document and quantify kinetic isotope fractionations during chemical and thermal (i.e., Soret) diffusion in liquids (silicate melts and water) and in the later years to include alloys and major minerals such as olivine and pyroxene. The research involved both laboratory experiments and applications to natural settings. The key idea is that major element zoning on natural geologic materials is common and can arise for either changes in melt composition during cooling and crystallization or from diffusion. The isotope effects associated with diffusion that we have documented are the key for determining whether or not the zoning observed in a natural system was the result of diffusion. Only in those cases were the zoning is demonstrably due to diffusion can use independently measured rates of diffusion to constrain the thermal evolution of the system.

  18. 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).

  19. 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...

  20. A sensitive and specific high performance liquid chromatographic assay for imidazole dipeptides and 3-methylhistidine in human muscle biopsies, serum and urine.

    PubMed

    Teahon, K; Rideout, J M

    1992-01-01

    A sensitive and specific high performance liquid chromatographic method is described for measuring imidazole dipeptides and 3-methylhistidine in human muscle biopsies, serum and urine. Muscle extract, serum or urine was reacted with o-phthaldialdehyde and the derivatives were separated by reversed phase chromatography with column switching and fluorescence detection.

  1. 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...

  2. High performance liquid chromatographic determination of ambroxol in the presence of different preservatives in pharmaceutical formulations.

    PubMed

    Koundourellis, J E; Malliou, E T; Broussali, T A

    2000-08-15

    A high-performance chromatographic method is described for simultaneous determination of ambroxol in the presence of different preservatives in syrups. The method separates ambroxol from methyl- ethyl-, propyl- and butyl paraben and from other multi-component mixtures. The retention behaviour of ambroxol and parabens as a function of both pH and mobile phase composition was investigated. The eluents were monitored with a UV detector at 247 nm. Linear relationships between the amount of pharmaceutical compounds and peak heights were confirmed at the concentrations of 0.74-14.08 microg ml(-1). The high recovery (no extraction of the samples is required) and the low %RSD confirm the suitability of the proposed method for the determination of ambroxol in different pharmaceutical preparations.

  3. 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)

  4. 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)

  5. Liquid chromatographic determination of fenbendazole residues in pig tissues after treatment with medicated feed.

    PubMed

    Capece, B P; Pérez, B; Castells, E; Arboix, M; Cristòfol, C

    1999-01-01

    Fenbendazole (FBZ) is an anthelmintic widely used in farm animals to treat parasitic infestations. In pigs, it is administered in the food. The aim of this study was to validate an analytical method for the determination of FBZ and its metabolites in pig tissues. This method is based on oxidation of FBZ and its sulfoxide metabolite to the sulfone metabolite (FBZSO2). The limit of quantitation for this method is 20 ng FBZSO2/g for all tissues. The maximum residue limits (MRLs) established for FBZ and its metabolites in pig tissues are 50 ng/g for muscle, fat, and kidney and 500 ng/g for liver. This method is based on a liquid-liquid extraction followed by an oxidation with peracetic acid and a cleanup procedure based on 2 liquid-liquid extractions. Determination is achieved by high-performance liquid chromatography with ultraviolet detection. The present method is adjusted to the MRL established for FBZ and its metabolite residues. The analysis of the residues shows that after 72 h posttreatment, no FBZSO2 was detected in muscle, fat, and kidney and that liver levels were below the MRL.

  6. Ionic-liquid based dispersive liquid-liquid microextraction followed by high performance liquid chromatographic determination of anti-hypertensives in rat serum.

    PubMed

    Rao, R Nageswara; Raju, S Satyanarayana; Vali, R Mastan

    2013-07-15

    A novel, simple and eco-friendly ionic liquid based dispersive liquid-liquid microextraction followed by HPLC determination of anti-hypertensive drugs viz., eprosartan, valasartan, irbesartan, losartan and telmisartan in rat serum has been developed and validated. Experimental parameters influencing the extraction efficiency, nature and volume of the ionic liquid, dispenser solvent, extraction time and effect of salt were optimized. Under the optimum conditions, the extraction recoveries were between 92.85 and 98.50%. The relative standard deviations of intra-and inter-day accuracy varied between 1.9 and 9.1% (n=3). The linearity of the proposed method was 0.1-20μg/mL with coefficients of determination varying between 0.9979 and 0.9992.

  7. 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.

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

    PubMed

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

    2012-07-15

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

  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. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. 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.

  11. Liquid chromatographic determination of quinolones in water and human urine samples after microextraction by packed sorbent.

    PubMed

    Rani, Susheela; Kumar, Ashwini; Malik, Ashok Kumar; Singh, Baldev

    2012-01-01

    A method for the simultaneous determination of quinolones in water and urine samples by microextraction in a sorbent-packed syringe (MEPS) with LC is described. MEPS is a new miniaturized SPE technique that can be used with chromatographic instruments without any modifications. In MEPS, approximately 1 mg of the solid packing material is inserted into a syringe (100-250 microL) as a plug. Sample preparation takes place on the packed bed. The new method is promising, easy to use, economical, and rapid. The determination of quinolones in groundwater and urine was performed using MEPS as a sample preparation method with LC-UV determination. Four quinolone antibiotics--enrofloxacin, enoxacin, danofloxacin, and nalidixic acid--in groundwater and urine samples were used as analytes. The extraction recovery was found to be between 64.9 and 98.9%. The results showed high correlation coefficients (R2 > 0.992) for all of the analytes within the calibration range. The LOQ was between 0.091 and 0.315 ng/mL.

  12. Liquid chromatographic resolution of proton pump inhibitors including omeprazole on a ligand exchange chiral stationary phase.

    PubMed

    Ha, Jin Joo; Choi, Hee Jung; Jin, Jong Sung; Jeong, Euh Duck; Hyun, Myung Ho

    2010-10-08

    A ligand exchange chiral stationary phase (CSP) developed previously in this laboratory by bonding (R)-phenylglycinol derivative, sodium N-[(R)-2-hydroxy-1-phenylethyl]-N-undecylaminoacetate, to silica gel was successfully applied to the resolution of proton pump inhibitors (PPIs) including omeprazole, pantoprazole, lansoprazole and rabeprazole. For example, the separation factors (α) for the resolution of omeprazole, pantoprazole, lansoprazole and rabeprazole were 4.27, 5.28, 2.77 and 4.06, respectively, and the resolutions (R(S)) were 2.53, 2.55, 1.93, and 2.01, respectively, when 65% acetonitrile aqueous solution containing 0.5mM CuSO(4) and 0.05mM triethylamine was used as a mobile phase. Based on the chromatographic behaviors for the resolution of PPI analogues on CSP 1, a chiral recognition mechanism utilizing the sulfoxide oxygen and the benzimidazole ring nitrogen of PPIs as bidentate coordination donors to form an enantioselective ternary complex with the central Cu(II) ion and the chiral stationary bidentate ligand was proposed. Copyright © 2010 Elsevier B.V. All rights reserved.

  13. Isocratic rapid liquid chromatographic method for simultaneous determination of carotenoids, retinol, and tocopherols in human serum.

    PubMed

    Thibeault, Denis; Su, Haixiang; MacNamara, Elizabeth; Schipper, Hyman M

    2009-04-15

    An improved isocratic and rapid HPLC method was developed for the measurement of carotenoids, retinol and tocopherols in human serum. Vitamins were extracted with hexane. Mobile phase consisted of a mixture acetonitrile:methylene chloride:methanol with 20 mM ammonium acetate. This method used a small bead size (3 microm) Spherisorb ODS2 column with titane frits. Diode array and fluorescence detectors were used respectively for the detection of carotenoids and retinol/tocopherols. Chromatographic separation was complete in 13 min for beta-cryptoxanthin, cis-trans-lycopene, alpha-carotene, beta-carotene, cis-beta-carotene, retinol, delta-tocopherol, gamma-tocopherol and alpha-tocopherol. Echinenone and tocol were employed as internal standards for diode array and fluorescence detection. Accuracy was validated using standard reference material (SRM) 968C. Intra-assay and inter-assay precision were respectively 0.2-7.3% and 3.6-12.6%. Sensitivity was verified using the ICH recommendations and the limit of detection (LOD) obtained was sufficient for routine clinical application.

  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. A validated stability indicating ultra performance liquid chromatographic method for determination of impurities in Esomeprazole magnesium gastro resistant tablets.

    PubMed

    Nalwade, Santaji Uttam; Reddy, Vangala Ranga; Rao, Dantu Durga; Morisetti, Nagendra Kumar

    2012-01-05

    A novel gradient reversed-phase ultra performance liquid chromatographic method has been developed for quantitative determination of Esomeprazole magnesium and its seven impurities in pharmaceutical dosage forms. Chromatographic separation has been achieved on an Acquity BEH C18, 50mm×2.1mm, 1.7μm with buffered mobile phase consisting solvent A (0.04molar (M) glycine (pH 9.0) buffer) and solvent B (mixture of acetonitrile and Milli-Q water in the ratio 90: 10 (v/v); respectively) delivered at flow rate of 0.21mL min(-1) and the detection wavelength 305nm. Resolution of Esomeprazole magnesium and all the seven potential impurities has been achieved greater than 2.0 for all pairs of compounds. The drug was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Esomeprazole magnesium was found to degrade significantly in oxidative and acid hydrolysis stress conditions and stable in base, hydrolytic and photolytic degradation conditions. The degradation products were well resolved from main peak and its impurities, thus proved the stability indicating power of the method. The stress samples were assayed against a reference standard and the mass balance was found to be close to 99.1%. So this method was also suitable for Assay determination of Esomeprazole magnesium in pharmaceutical dosage forms. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. 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

  17. New liquid chromatographic-chemometric approach for the determination of sunset yellow and tartrazine in commercial preparation.

    PubMed

    Dinç, Erdal; Aktaş, A Hakan; Ustündağ, Ozgür

    2005-01-01

    A new liquid chromatographic (LC)-chemometric approach was developed for the determination of sunset yellow (SUN) and tartrazine (TAR) in commercial preparations. This approach uses LC and chemometric calibration methods, i.e., classical least-squares (CLS), principal component regression (PCR), and partial-least squares (PLS), simultaneously. The combined LC-chemometric approaches, denoted as LC-CLS, LC-PCR, and LC-PLS, are based on photodiode array (PDA) detection at multiple wavelengths. Optimum chromatographic separation of SUN and TAR with allura red as the internal standard (IS) was obtained by using a Waters Symmetry C18 column, 5 microm, 4.6 x 250 mm, and 0.2 M acetate buffer (pH 5)-acetonitrile-methano-bidistilled water (55 + 20 + 15 + 10, v/v) as the mobile phase at a flow rate of 1.9 mL/min. The LC data sets consisting of the ratios of analyte peak areas to the IS peak area were obtained by using PDA detection at 5 wavelengths (465, 470, 475, 480, and 485 nm). LC-chemometric calibrations for SUN and TAR were separately constructed by using the relationship between the peak-area ratio and the training sets for each colorant. LC-chemometric approaches were tested for different synthetic mixtures containing SUN and TAR in the presence of the IS. These LC-chemometric calibrations were applied to a commercial preparation of the 2 colorants. The experimental results of the LC-chemometric approaches were compared with those obtained by a developed classical LC method using single-wavelength detection.

  18. A liquid chromatographic method for the determination of histamine in immunoglobulin preparation using solid phase extraction and pre-column derivatization.

    PubMed

    Kim, Nam Hee; Park, Youmie; Jeong, Eun Sook; Kim, Chang-Soo; Jeoung, Min Kyo; Kim, Kyoung Soon; Hong, Seung-Hwa; Son, Jong-Keun; Hong, Jin Tae; Park, Il-Young; Moon, Dong-Cheul

    2007-10-01

    An immunoglobulin (IgG) preparation with micro-amount of histamine fixed on the active protein fraction has been used to increase the resistance to allergic reactions. However, excessive histamine may cause hypo- or hypertension, headache, or anaphylactic shock and so the histamine content of the drug is strictly controlled by a regulation: 0.15 microg of histamine dihydrochloride is allowed for 12 mg of immunoglobulin. In this study, a liquid chromatographic method to determine micro-amount of histamine in the pharmaceutical was developed and validated. This method include a sample cleanup by a solid phase extraction (SPE) using a polystyrene-divinyl benzene (PS-DVB) polymeric sorbent and high-performance liquid chromatography after precolumn fluorescent labeling of the histamine with o-phthaldialdehyde. The drug sample was loaded to the SPE cartridge after adjusting to pH 9.5. After successive washings of the cartridge with water and 30% aqueous methanol, histamine was then eluted with 100 mM sodium acetate (pH 9.5)-methanol (20:80, v/v). An aliquot from the eluate was labeled with o-phthaldialdehyde-mercaptoethanol (OPA-ME) for fluorescence detection at the excitation maximum of 340 nm and emission maximum of 450 nm. HPLC analysis was performed on a phenyl-hexyl column with an acetonitrile-phosphate buffer (pH 6.8; 50 microM) (35:65, v/v) as the mobile phase. The retention times of histamine and 3-methylhistamine (IS) were approximately 7.2 and 9.5 min, respectively. The quantitation range was between 0.01-0.2 mg/mL of histamine showing good linearity (r=0.9996). This analytical method would provide a potential mean for the strict control of histamine content in the pharmaceutical product.

  19. High pressure liquid chromatographic determination of carbocisteine in human plasma and urine.

    PubMed

    Bron, J

    1986-04-25

    A method is described for the direct analysis of the amino acid carbocisteine in plasma and urine samples, following reaction with dabsyl chloride. Dabsylated carbocisteine is subjected to high pressure liquid chromatography with spectrophotometric detection at 425 nm. The usefulness of the method for bioavailability studies is discussed and compared with methods currently in use.

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

    USDA-ARS?s Scientific Manuscript database

    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...

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

    PubMed

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

    2015-05-01

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

  2. 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…

  3. 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…

  4. High-performance liquid chromatographic determination of alpha-tocopherol in inclusion complexes with cyclodextrins.

    PubMed

    Gierlach-Hładoń, Teresa; Lange, Kinga

    2012-01-01

    A new high performance liquid chromatography (HPLC)-based method is proposed for the determination of vitamin E, free and in inclusion complexes with natural beta-cyclodextrin and its 2-hydroxy derivative. The method has been validated on the basis of the following parameters: specificity, selectivity, linearity, precision, range and recovery.

  5. Theory and use of the pseudophase model in gas-liquid chromatographic enantiomeric separations.

    PubMed

    Pino, Verónica; Lantz, Andrew W; Anderson, Jared L; Berthod, Alain; Armstrong, Daniel W

    2006-01-01

    The theory and use of the "three-phase" model in enantioselective gas-liquid chromatography utilizing a methylated cyclodextrin/polysiloxane stationary phase is presented for the first time. Equations are derived that account for all three partition equilibria in the system, including partitioning between the gas mobile phase and both stationary-phase components and the analyte equilibrium between the polysiloxane and cyclodextrin pseudophase. The separation of the retention contributions from the achiral and chiral parts of the stationary phase can be easily accomplished. Also, it allows the direct examination of the two contributions to enantioselctivity, i.e., that which occurs completely in the liquid stationary phase versus the direct transfer of the chiral analyte in the gas phase to the dissolved chiral selector. Six compounds were studied to verify the model: 1-phenylethanol, alpha-ionone, 3-methyl-1-indanone, o-(chloromethyl)phenyl sulfoxide, o-(bromomethyl)phenyl sulfoxide, and ethyl p-tolylsulfonate. Generally, the cyclodextrin component of the stationary phase contributes to retention more than the bulk liquid polysiloxane. This may be an important requirement for effective GC chiral stationary phases. In addition, the roles of enthalpy and entropy toward enantiorecognition by this stationary phase were examined. While enantiomeric differences in both enthalpy and entropy provide chiral discrimination, the contribution of entropy appears to be more significant in this regard. The three-phase model may be applied to any gas-liquid chromatography stationary phase involving a pseudophase.

  6. Sample preparation and high-performance liquid chromatographic analysis of deoxyribonucleoside triphosphates in individual rat embryos.

    PubMed

    Mole, M L; Hunter, D L; Gao, P; Lau, C

    1998-06-01

    A rapid, robust, and sensitive method has been developed to measure concentrations of deoxyribonucleoside triphosphates in individual, day 14 rat embryos by modifying and optimizing existing methods for cellular extracts. Significant changes include: (i) oxidative degradation of ribonucleoside triphosphates using methylamine at lower pH (decreased from 6.5 to 4.0) to improve poor HPLC peak shape of early eluting nucleotides; (ii) glass fiber disc solid-phase extraction of the reaction mixture, which dramatically reduces impurities that interfere with nucleotide measurement, eliminates the necessity of column regeneration, and allows mobile phase recycling; and (iii) lower ionic strength (reduced from 0.4 to 0.26 or 0.12 M ammonium phosphate) and higher pH (increased from 3.25 to 5.55 or 6.98, respectively) mobile phase, conditions which are less destructive to the column's bonded phase and silica support, thereby contributing to longer column life. Enhancements include: (i) filtration of the sample prior to HPLC injection and addition of an in-line filter, guard column, and saturating precolumn of silica in the mobile phase flow, which aids substantially in extending column life and improves chromatographic stability, and (ii) inclusion of an internal standard to correct for mechanical losses. Limits of determination at a signal to noise ratio of 6:1 range from 5.5 to 12 pmol on-column or 0.41 to 0.87 pmol/mg of embryonic tissue depending on the specific nucleotide. Recoveries are quantitative for all nucleotides, and interassay variabilities are between 5 and 7% when quantified by peak height. The method has also been applied successfully to analysis of murine erythroleukemic cell cultures and this, when coupled with the embryo results, suggests its general utility.

  7. 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.

  8. High-performance Liquid Chromatographic Ultraviolet Detection of Nilotinib in Human Plasma from Patients with Chronic Myelogenous Leukemia, and Comparison with Liquid Chromatography-Tandem Mass Spectrometry.

    PubMed

    Nakahara, Ryosuke; Satho, Yuhki; Itoh, Hiroki

    2016-11-01

    A method for determining nilotinib concentration in human plasma is proposed using high-performance liquid chromatography and ultraviolet detection. Nilotinib and the internal standard dasatinib were separated using a mobile phase of 0.5% Na2 PO4 H2 O (pH 2.5)-acetonitrile-methanol (55:25:20, v/v/v) on a Capcell Pak C18 MG II column (250 × 4.6 mm) at a flow rate of 1.0 ml/min, and ultraviolet measurement at 250 nm. The calibration curve exhibited linearity over the nilotinib concentration range of 50-2,500 ng/ml at 250 nm, with relative standard deviations (n = 5) of 7.1%, 2.5%, and 2.9% for 250, 1,500, and 2,500 ng/ml, respectively. The detection limit for nilotinib was 5 ng/ml due to three blank determinations (ρ = 3). This method was successfully applied to assaying nilotinib in human plasma samples from patients with chronic myelogenous leukemia. In addition, we compared the results with those measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) at BML, Inc. (a commercial laboratory). A strong correlation was observed between the nilotinib concentrations measured by our high-performance liquid chromatographic method and those obtained by LC/MS-MS (r(2) = 0.988, P < 0.01). © 2016 Wiley Periodicals, Inc.

  9. 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

  10. Multicomponent analysis of replacement liquids of electronic cigarettes using chromatographic techniques.

    PubMed

    Kavvalakis, Matthaios P; Stivaktakis, Polychronis D; Tzatzarakis, Manolis N; Kouretas, Dimitrios; Liesivuori, Jyrki; Alegakis, Athanasios K; Vynias, Dionysios; Tsatsakis, Aristidis M

    2015-05-01

    The electronic cigarette (e-cig) is an invention of the past few years and its popularity is rapidly growing all over the world. A rapid multicomponent analytical protocol for the analysis of the replacement liquids (e-liquids) of e-cig was developed using gas (GC) and liquid chromatography (LC)-mass spectrometry (MS). GC-MS-based methods were developed for the determination of the main humectants and polycyclic aromatic hydrocarbons (PAHs). For the determination and quantification of nicotine (NIC) and nitrosamines, appropriate LC-MS-based methods were developed. The approbated methods were applied for the analysis of 263 e-liquid samples obtained from the Greek market. The instruments response was linear; the limits of quantification ranged from 0.003 μg/mL for three PAHs to 1.187 μg/mL for glycerol. The precision was <16% for all analytes, while the mean accuracy ranged from 99.1% for NIC to 106.6% for the flavor 2,5-dimethylpyrazine. The measured concentrations of NIC were correlated with the theoretical concentrations as reported by the manufacturers. An analog relation between the concentration of the glycerol and of propylene glycol was noticed. The frequency of detection of flavors ranged from 30.4% for the methyl cyclopentenolone to 5.3% for 3.4-dimethoxybenzaldehyde. Nitrosamines and PAHs were not detected in any sample. Because a similar analytical protocol was not available from the existing literature so far, our study offers the advantage of complete analytical methods for rapid and simultaneous multicomponent identification. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Gas-liquid chromatographic measurement of lignocaine in small samples of canine myocardium after enzymatic digestion.

    PubMed Central

    Holt, D W; Loizou, M; Wyse, R K

    1979-01-01

    A method is described whereby lignocaine can be measured in small samples of canine myocardium. A proteolytic enzyme is used to digest the tissue, and the drug, together with an internal standard, is subsequently extracted into an organic solvent and measured by gas-liquid chromatography. The method is reproducible using tissue samples as small as 50 mg and appears to be suitable for the measurement of a number of drugs in small samples of tissue. PMID:429588

  12. High-performance liquid chromatographic method for the determination of dansyl-polyamines

    Treesearch

    Subhash C. Minocha; Rakesh Minocha; Cheryl A. Robie

    1990-01-01

    This paper describes a fast reliable, and a sensitive technique for the separation and quantification of dansylated polyamines by high-performance liquid chromatography. Using a small 33 x 4.6 mm I.D., 3 ?m particle size, C18 reversed-phase cartridge column and a linear gradient of acetonitrile-heptanesulfonate (10 mM, pH 3.4...

  13. 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.

  14. Direct injection isocratic high-performance liquid chromatographic analysis of mitomycin C in plasma.

    PubMed

    Song, D; Au, J L

    1996-02-09

    A direct injection high-performance liquid chromatography method is described for the determination of mitomycin C (MMC) in human plasma. The stationary phase consisted of hydrophilic and hydrophobic functional groups covalently bound to silicone-coated silica beads (CAPCELL PAK MF Ph-1, 150x4.6 mm I.D., 5 microns). A mobile phase using 100% water gave a better separation of MMC from endogenous interferences as compared to a mobile phase with 12.5% acetonitrile and 2.5 mM phosphate buffer (pH 6.9). Using water as the eluent (1 ml/min) and UV detection at 365 nm, MMC was found to elute at 5.0 min with a peak width of 0.3 min, whereas endogenous interferences eluted before 3 min. Total assay time per sample was 6 min. Internal standard was not required because the recovery of MMC was nearly complete, about 90% from 20 to 5000 ng/ml. The standard curve was linear from 20 to 5000 ng/ml in plasma, and the intra-and inter-day variation was between 3 to 6%. The lower detection limit was 5 ng/ml with a 25 microliters sample, which represents a two- to four-fold improvement over the 10 ng/ml detection limit by previous methods using liquid-liquid extraction and comparable sample size. The simplicity of this method, i.e., no sample extraction, no internal standard, 100% aqueous mobile phase, isocratic elution and short analysis time (6 min/sample), makes it suitable for large scale routine sample analysis, whereas its small sample volume requirement and high sensitivity are useful for pharmacokinetic studies in small animals where limited sample is available.

  15. Correlation of liquid chromatographic and biological assay for potency assessment of filgrastim and related impurities.

    PubMed

    Skrlin, Ana; Kosor Krnic, Ela; Gosak, Darko; Prester, Berislav; Mrsa, Vladimir; Vuletic, Marko; Runac, Domagoj

    2010-11-02

    In vivo and in vitro potency assays have always been a critical tool for confirmation of protein activity. However, due to their complexity and time consuming procedures, it remains a challenge to find an alternative analytical approach that would enable their replacement with no impact on the quality of provided information. The goal of this research was to determine if a correlation between liquid chromatography assays and in vitro biological assay could be established for filgrastim (recombinant human granulocyte-colony stimulating factor, rhG-CSF) samples containing various amounts of related impurities. For that purpose, relevant filgrastim related impurities were purified to homogeneity and characterized by liquid chromatography and mass spectrometry. A significant correlation (R(2)>0.90) between the two types of assays was revealed. Potency of oxidized filgrastim was determined to be approximately 25% of filgrastim stated potency (1 x 10(8)IU/mg of protein). Formyl-methionine filgrastim had potency of 89% of the filgrastim stated potency, while filgrastim dimer had 67% of filgrastim stated potency. A mathematical model for the estimation of biological activity of filgrastim samples from chromatography data was established and a significant correlation between experimental potency values and potency values estimated by the mathematical model was obtained (R(2)=0.92). Based on these results a conclusion was made that reversed phase high performance liquid chromatography could be used as an alternative for the in vitro biological assay for potency assessment of filgrastim samples. Such an alternative model would enable substitution of a complex and time consuming biological assay with a robust and precise instrumental method in many practical cases. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  16. High-pressure liquid chromatographic assay of sulbactam in plasma, urine, and tissue.

    PubMed

    Bawdon, R E; Madsen, P O

    1986-08-01

    A reverse-phase high-pressure liquid chromatography method for the quantitation of sulbactam in plasma, urine, and tissue is described. The assay used the formation of an imidazole derivative followed by extraction with acetonitrile and dichloromethane and used UV absorbance for detection. The mobile phase consisted of acetonitrile, tetrabutylammonium hydroxide, and phosphate buffer. The assay was linear from 100 micrograms/ml (g of tissue) to 1 microgram/ml (g). Within- and between-batch recovery was greater than 90%. The coefficient of variation was generally less than 15%. There were no interfering peaks in the quantitation of sulbactam.

  17. 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.

  18. 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.

  19. 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.

  20. Liquid chromatographic analysis of supercritical carbon dioxide extracts of Schizandra chinensis.

    PubMed

    Bártlová, Milena; Opletal, Lubomír; Chobot, Vladimír; Sovová, Helena

    2002-04-25

    Six major lignans (schizandrin, gomisin A, deoxyschizandrin, y-schizandrin, gomisin N, wuweizisu C) in the caulomas and leaves of Schizandra chinensis (Turcz.) Baill., and cinnamic acid in the leaves of the plant, were quantitatively analysed by high-performance liquid chromatography in reversed-phase mode with UV detection. Resolution of the determined lignans was evaluated for two multistep gradients applied. Samples for HPLC analysis were prepared by extraction with supercritical carbon dioxide at pressures of 20-27 MPa and temperatures of 40-60 degrees C. Kinetics of the extraction of individual components was measured and simulated with a model.

  1. Reverse phase ion pair high pressure liquid chromatographic determination of ethylenediaminetetraacetic acid in crabmeat and mayonnaise.

    PubMed

    Perfetti, G A; Warner, C R

    1979-09-01

    A method is described for the determination of ethylenediaminetetraacetic acid (EDTA) in crabmeat and mayonnaise. EDTA is extracted from the food sample with water and converted to its copper chelate, which is then quantitated by reverse phase ion pair high pressure liquid chromatography with ultraviolet detection. Maximum sensitivity is obtained with detection at about 254 nm; higher wavelengths may be used for enhanced specificity. Cleanup procedures for crabmeat and mayonnaise were improved by using a radiotracer method. Analyses of crabmeat and mayonnaise samples spiked at 3 different levels showed greater than 90% recovery of EDTA.

  2. Chromatographic finger print analysis of anti-inflammatory active extract fractions of aerial parts of Tribulus terrestris by HPTLC technique

    PubMed Central

    Mohammed, Mona Salih; Alajmi, Mohamed Fahad; Alam, Perwez; Khalid, Hassan Subki; Mahmoud, Abelkhalig Muddathir; Ahmed, Wadah Jamal

    2014-01-01

    Objective To develop HPTLC fingerprint profile of anti-inflammatory active extract fractions of Tribulus terrestris (family Zygophyllaceae). Methods The anti-inflammatory activity was tested for the methanol and its fractions (chloroform, ethyl acetate, n-butanol and aqueous) and chloroform extract of Tribulus terrestris (aerial parts) by injecting different groups of rats (6 each) with carrageenan in hind paw and measuring the edema volume before and 1, 2 and 3 h after carrageenan injection. Control group received saline i.p. The extracts treatment was injected i.p. in doses of 200 mg/kg 1 h before carrageenan administration. Indomethacin (30 mg/kg) was used as standard. HPTLC studies were carried out using CAMAG HPTLC system equipped with Linomat IV applicator, TLC scanner 3, Reprostar 3, CAMAG ADC 2 and WIN CATS-4 software for the active fractions of chloroform fraction of methanol extract. Results The methanol extract showed good antiedematous effect with percentage of inhibition more than 72%, indicating its ability to inhibit the inflammatory mediators. The methanol extract was re-dissolved in 100 mL of distilled water and fractionated with chloroform, ethyl acetate and n-butanol. The four fractions (chloroform, ethyl acetate, n-butanol and aqueous) were subjected to anti-inflammatory activity. Chloroform fraction showed good anti-inflammatory activity at dose of 200 mg/kg. Chloroform fraction was then subjected to normal phase silica gel column chromatography and eluted with petroleum ether-chloroform, chloroform-ethyl acetate mixtures of increasing polarity which produced 15 fractions (F1-F15). Only fractions F1, F2, F4, F5, F7, F9, F11 and F14 were found to be active, hence these were analyzed with HPTLC to develop their finger print profile. These fractions showed different spots with different Rf values. Conclusions The different chloroform fractions F1, F2, F4, F5, F7, F9, F11 and F14 revealed 4, 7, 7, 8, 9, 7, 7 and 6 major spots, respectively. The

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

    PubMed

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

    2014-01-01

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

  4. Liquid chromatographic-tandem mass spectrometric method for the quantitation of sildenafil in human plasma.

    PubMed

    Wang, Yingwu; Wang, Jiang; Cui, Yimin; Fawcett, J Paul; Gu, Jingkai

    2005-12-15

    A method to determine sildenafil in human plasma involving liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed. Sildenafil and the internal standard (I.S.), diazepam, are extracted from human plasma with ether-dichloromethane (3:2, v/v) at basic pH and analyzed by reversed-phase high-performance liquid chromatography (HPLC) using methanol-10mM ammonium acetate pH 7.0 (85:15, v/v) as the mobile phase. Detection by electrospray positive ionization mass spectrometry in the multiple-reaction monitoring mode was linear over the concentration range 0.125-40.0 ng/ml. Intra- and inter-day precision of the assay at four concentrations within this range were 2.5-8.0%. The method was used to evaluate plasma concentration-time profiles in healthy volunteers given an oral dose of 20mg sildenafil as a combination tablet also containing apomorphine.

  5. Development of a liquid chromatographic method for bioanalytical applications with sildenafil.

    PubMed

    Sheu, Ming-Thau; Wu, An-Bang; Yeh, Geng-Cheng; Hsia, Angel; Ho, Hsiu-O

    2003-07-05

    An improved HPLC method was developed for the determination of sildenafil concentrations in plasma. Analysis of sildenafil in plasma samples was simplified by utilizing a one-step liquid-liquid extraction after alkaline treatment of only 1 ml of plasma. The lower limit of quantitation was 10 ng/ml with a coefficient of variation of less than 20%. A linear range was found to exist from 10 to 1000 ng/ml. This HPLC method was validated with precisions (coefficient of variation, C.V.) for inter- and intra-day runs of 0.41-11.15% and 0.36-8.05%, respectively, and accuracies (the relative error of the mean, REM) for inter- and intra-day runs of -8.72-6.81% and 0.41-11.15%, respectively. A bioavailability study of sildenafil was performed on one normal healthy male volunteer by analyzing sildenafil plasma concentrations with this validated HPLC method. Results demonstrated that this HPLC method is appropriate for applications to bioavailability studies of sildenafil. In addition, an example of the influence of the co-administration of grapefruit juice on sildenafil pharmacokinetics in a healthy volunteer is presented.

  6. 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

  7. 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.

  8. Liquid chromatographic determination of St. John's wort components in functional foods.

    PubMed

    de Jager, Lowri S; Perfetti, Gracia A; Diachenko, Gregory W

    2004-01-01

    A method was developed for determination of St. John's wort marker compounds hypericin, pseudohypericin, hyperforin, and adhyperforin in functional foods. Solid-phase extraction provided analyte extraction and significant sample cleanup prior to analysis using liquid chromatography (LC) with UV and fluorescence detection. In addition to quantification using LC-UV, confirmation was made with electrospray ionization LC mass spectrometry (LC/MS). Several commercially available tea and drink products claiming to contain St. John's wort were tested. Recoveries ranged from 51 to 98% for the liquid samples. Comparison of the concentrations in 4 St. John's wort teas showed a variation in analyte concentration (1044-10 ng/mL marker compounds in brewed tea) and composition. No marker compounds were found in the beverages, indicating possible decomposition of the marker compounds caused by low pH and/or exposure to light. A solvent extraction procedure was developed for analysis of the marker compounds from solid samples. Analytes were detected at low parts per million, with an average recovery of 75%. No St. John's wort components were found in the 2 solid functional food samples analyzed.

  9. High-performance liquid chromatographic assay of sulbactam using pre-column reaction with 1,2,4-triazole.

    PubMed

    Haginaka, J; Wakai, J; Yasuda, H; Uno, T; Nakagawa, T

    1985-05-31

    A high-performance liquid chromatographic (HPLC) method for the determination of sulbactam in human and rat plasma and urine has been developed. Sulbactam was reacted with 1,2,4-triazole to yield a product having an ultraviolet absorption maximum at 326 nm. The product was separated using reversed-phase HPLC from the regular components of plasma and urine with an ion-pair buffer at 50 degrees C and detected at the ultraviolet maximum. The limits of accurate determination were 0.2 and 1.0 micrograms/ml in plasma and urine, respectively. The coefficients of variation of inter- and intra-assays in human plasma spiked at 4.0 micrograms/ml (n = 5) were 1.02 and 3.05%, respectively. Coexisting cefoperazone, penicillins, or the alkaline degradation product(s) of sulbactam did not interfere in the sulbactam assay. The pharmacokinetic behaviour of sulbactam and cefoperazone coadministered to rats was estimated by moment analysis.

  10. Validated High-Performance Liquid Chromatographic Method for the Estimation of Rosuvastatin Calcium in Bulk and Pharmaceutical Formulations

    PubMed Central

    Ashour, Safwan; Omar, Soulafa

    2011-01-01

    A reversed-phase high-performance liquid chromatographic method was developed and validated for the determination of rosuvastatin calcium in pharmaceutical dosage forms. The determination was performed on a Nucleodur column C8 (250 × 4.6 mm i.d., 5 μm particle size); the mobile phase consisted of a mixture of 0.1M formic acid and methanol (25:75, v/v), pumped at a flow rate 1.0 mL min-1. The photodiode array detector was operated at 280 nm. The retention times for rosuvastatin and fluvastatin, which was used as internal standard, were 3.98 and 7.78 min, respectively. Linearity range (r2 better than 0.999, n=6) was 3.0-1602.0 μg mL-1 with limit of detection value of 0.12 μg mL-1. The precision of the method was demonstrated using intra- and inter-day assay RSD% values which were less than 2.40%, while the recovery was 99.86-102.86%. The method was applied in the quality control of commercial tablets and content uniformity test and proved to be suitable for rapid and reliable quality control. PMID:23675248

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

    PubMed

    Li, Ruiping; Zhang, Yi; Lee, Charles C; Lu, Rongrong; Huang, Yingping

    2010-03-12

    A simple, precise, and accurate hydrophilic interaction liquid chromatographic (HILIC) method has been developed for the determination of five aromatic amines in environmental water samples. Chromatography was carried out on a bare silica column, using a mixture of acetonitrile and a buffer of NaH(2)PO(4)-H(3)PO(4) (pH 1.5, containing 10mM NaH(2)PO(4)) (85:15, v/v) as a mobile phase at a flow rate of 1 mL min(-1). Aromatic amines were detected by UV absorbance at 254 nm. The linear range of amines was good (r(2)>0.998) and limit of detection (LOD) within 0.02-0.2 mg L(-1) (S/N=3). The retention mechanism for the analytes under the optimum conditions was determined to be a combination of adsorption, partition and ionic interactions. The proposed method was applied to the environmental water samples. Aromatic amines were isolated from aqueous samples using solid-phase extraction (SPE) with Oasis HLB cartridges. Recoveries of greater than 75% with precision (RSD) less than 12% were obtained at amine concentrations of 5-50 microg L(-1) from 100mL river water and influents from a wastewater treatment plant (WWTP). The present HILIC technique proved to be a viable method for the analysis of aromatic amines in the environmental water samples.

  12. 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.

  13. 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.

  14. Development and validation of liquid chromatographic and UV derivative spectrophotometric methods for the determination of famciclovir in pharmaceutical dosage forms.

    PubMed

    Srinubabu, Gedela; Sudharani, Batchu; Sridhar, Lade; Rao, Jvln Seshagiri

    2006-06-01

    A high-performance liquid chromatographic method and a UV derivative spectrophotometric method for the determination of famciclovir, a highly active antiviral agent, in tablets were developed in the present work. The various parameters, such as linearity, precision, accuracy, specificity, robustness, limit of detection and limit of quantitation were studied according to International Conference on Harmonization guidelines. HPLC was carried out by using the reversed-phase technique on an RP-18 column with a mobile phase composed of 50 mM monobasic phosphate buffer and methanol (50 : 50; v/v), adjusted to pH 3.05 with orthophosphoric acid. The mobile phase was pumped at a flow rate of 1 ml/min and detection was made at 242 nm with UV dual absorbance detector. The first derivative UV spectrophotometric method was performed at 226.5 nm. Statistical analysis was done by Student's t-test and F-test, which showed no significant difference between the results obtained by the two methods. The proposed methods are highly sensitive, precise and accurate and therefore can be used for its Intended purpose.

  15. Liquid chromatographic determination of Lake Red C Amine and 2-naphthol in D and C red No. 8

    SciTech Connect

    Scher, A.L.; Calvey, R.J.

    1988-01-01

    A method is described for the determination of the intermediates in D and C Red No. 8 by reverse-phase liquid chromatography (LC). The pigment is dissolved in boiling 95% ethanol-water (1 + 1) and then precipitated. The filtrate is chromatographed by gradient elution. Calibrations from peak areas at 254 nm for Lake Red C Amine sodium salt (LRCA-Na) and at 229 nm for 2-naphthol were linear, with prediction limits of 0.200 +/- 0.006% and 0.200 +/- 0.003%, respectively, for the maximum permitted levels. Calibration limits of determination were 0.01% for LRCA-Na and 0.006% for 2-naphthol. A 99% confidence level was used. Recoveries were 100.0-100.4% for LRCA-Na and 97.1-101.8% for 2-naphthol, each added at levels of 0-025-0.2%. Certified lots of D and C Red No. 8 that were analyzed by the LC method contained higher levels of LRCA-Na but the same levels of 2-naphthol when compared to results obtained previously by a cellulose column method, in which the pigment is not dissolved. The solubilities of D and C No. 8 in hot and room temperature solutions of 95% ethanol-water (1 + 1), water, and 95% ethanol were estimated.

  16. Comparison evaluation of liquid chromatographic and bioassay methods of analysis for determination of paralytic shellfish poisons in shellfish tissues.

    PubMed

    Salter, J E; Timperi, R J; Hennigan, L J; Sefton, L; Reece, H

    1989-01-01

    A liquid chromatographic (LC) method was compared with the AOAC mouse bioassay method (18.086-18.092) for determination of paralytic shellfish toxins in shellfish tissues. Shellfish samples were collected from Massachusetts coastal waters as part of a state surveillance program, and extracts of shellfish meat were analyzed for toxins by using both analytical methods. Overall correlation of the LC and bioassay methods is good (r = 0.943), but for samples with toxicities less than 100 micrograms saxitoxin/100 g shellfish meat, the correlation is significantly less (r = 0.531). Limits of detection are 10 micrograms saxitoxin/100 g shellfish meat and 40 micrograms saxitoxin/100 g shellfish meat for the LC and bioassay methods, respectively. Analytical capacity of the LC method is limited to 12 samples/person-day compared with 30 samples/person-day for the bioassay. Sampling capacity of the LC method could be increased by using a fluorescence detector with a wider response range, which would eliminate the need for dilution of concentrated samples.

  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. Radioimmunoassay and liquid-chromatographic analysis for free cortisol in urine compared with isotope dilution-mass spectrometry

    SciTech Connect

    Lantto, O.

    1982-05-01

    Three different routine methods for analysis for urinary cortisol with those by a highly specific reference method based on isotope dilution-mass spectrometry (I) were compared. A ''high-performance'' liquid-chromatographic method (II) gave the most comparable results (regression coefficient 0.86, intercept 9 nmol/L). For some urines much lower values were obtained by I than by II. Two radioimmunoassay (III) methods, one involving direct assay and one involving extraction, gave less-accurate results (regression coefficients of 1.87 and 1.52 and intercepts of 86 and 12 nmol/L, respectively), although values obtained by III and by I correlated well (r = 0.95-0.99), indicating a relation between the free cortisol and the compounds interfering in III. The apparent accuracy for the extraction method was improved by using as calibration standards urine samples previously assayed by I (regression coefficient 0.90, intercept 6 nmol/L). All four methods investigated showed a statistically significant sex-related difference in 24-h urinary cortisol excretion; evidently such a finding should be a prerequisite in any such method proposed for routine use.

  19. Ultra-high performance liquid chromatographic method for the determination of polycyclic aromatic hydrocarbons in a passive environmental sampler.

    PubMed

    Purcaro, Giorgia; Moret, Sabrina; Bučar-Miklavčič, Milena; Conte, Lanfranco S

    2012-04-01

    Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous compounds released in the environment by different sources. The aim of the present work was to validate a solid-phase extraction (SPE) and a rapid ultra-high performance liquid chromatographic (UHPLC) method for the analysis of PAHs in a passive environmental sampler, namely a Dacron® (the commercial name of a synthetic fiber based on polyethylene terephthalate) textile. The elution temperature was optimized to improve the resolution of early-eluted compounds, namely acenaphthene (Ac) and fluorene (F). The UHPLC method lasts about 10 min and showed good linearity for all the 16 PAHs considered, with regression coefficients over 0.99. Recoveries, limits of detection (LODs), and limits of quantification (LOQs) of the SPE method were well within the performance criteria fixed by the Regulation n. 836/2011, namely 0.3 and 0.9 μg/kg, respectively. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. [Determination of phthalate plasticizers in foods by high performance liquid chromatography with gel permeation chromatographic clean-up].

    PubMed

    Zhang, Chunyu; Wang, Hui; Zhang, Xiaohui; Ma, Zhongqiang; Deng, Wanmei; Hu, Ke; Ding, Mingyu

    2011-12-01

    A method of gel permeation chromatography-high performance liquid chromatography (GPC-HPLC) was established for the simultaneous determination of 5 main phthalate plasticizers in foods (edible oil, instant noodles, fried pastries, Saqima, etc.). The samples were extracted with petroleum ether in an ultrasonator, purified by a GPC column, and analyzed by HPLC. The chromatographic separation was achieved on a Labtech-C18 column (250 mm x 4.6 mm, 5 microm) using acetonitrile and water mixture as the mobile phases in a gradient elution mode. The developed method exhibited a linear correlation coefficient of more than 0.997 and the detection limits of 3.25 - 13.4 microg/L. The spike recoveries were between 70.4% and 113.6% with the relative standard deviations (RSDs, n = 3) of 0.3% - 5.8% at the spiked level of 50 mg/L. This method is simple, rapid and practical, and can be used for the simultaneous determination of PAEs in grease food samples.

  1. Application of high-performance liquid chromatographic methodology to the analysis of hemoglobins synthesized in erythroid progenitor cells.

    PubMed

    Bhaumik, K; Huisman, T H

    1989-11-10

    High-performance liquid chromatography (HPLC) has been successfully used in the quantitation of the relatively minute amounts of hemoglobin types recovered from in vitro cultures of hemoglobin-synthesizing erythroid progenitor (BFU-E) cells. This reversed-phase HPLC method uses the Vydac C4 column and water-acetonitrile-trifluoroacetic acid as mobile phases; it has been applied to the study of fetal hemoglobin synthesis patterns in ten homozygous sickle cell anemia patients and a similar number of their heterozygous relatives along with a few normal control subjects. A significant increase in the total gamma chain level was observed in the BFU-E lysate samples corresponding to the whole blood lysates of all the patients and their heterozygous relatives, except in one patient with the beta S haplotype Mor. On the other hand, the relative level of the G gamma chains appeared to be decreased in the BFU-E lysate samples of all except the individuals carrying the Mor haplotype, where it is reversed. The method has considerable advantages over other chromatographic and electrophoretic procedures; it is extremely sensitive and allows quantitation of all different globin chains in one single chromatogram.

  2. 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.

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

    PubMed

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

    1997-09-26

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

  4. A novel two-dimensional liquid chromatographic system for the online toxicity prediction of pharmaceuticals and related substances.

    PubMed

    Li, Jian; Xu, Li; Shi, Zhi-guo; Hu, Min

    2015-08-15

    In this study, a novel two-dimensional liquid chromatographic (2D-LC) system was developed for simultaneous separation and toxicity prediction of pharmaceutical and its related substances. A conventional ODS column was used on the 1st-D to separate the sample; while, bio-partitioning micellar chromatography served as the 2nd-D to predict toxicity of the components. The established system was tested for the toxicity of ibuprofen and its impurities with known toxicity. With only one injection, ibuprofen and its impurities were separated on the 1st-D; and LC50 values of individual impurity were obtained based on the quantitative retention-activity relationships, which agreed well with the reported data. Furthermore, LC50 values of photolysis transformation products (TPs) of carprofen, ketoprofen and diclofenac acid (as unknown compounds) were screened in this 2D-LC system, which could be an indicator of the toxicity of these TPs and was meaningful for the environmental monitoring and drinking water treatment. The established 2D-LC system was cost-effective, time-saving and reliable, and was promising for fast online screening of toxicity of known and unknown analytes in the complex sample in a single step. It may find applications in environment, pharmaceutical and food, etc.

  5. An improved high-performance liquid chromatographic method for simultaneous determination of tocopherols, tocotrienols and γ-oryzanol in rice.

    PubMed

    Huang, Shao-Hua; Ng, Lean-Teik

    2011-07-22

    An improved normal phase high performance liquid chromatographic (NP-HPLC) method was developed for simultaneous quantification of eight vitamin E isomers (α-, β-, γ- and δ-tocopherols and α-, β-, γ- and δ-tocotrienols) and γ-oryzanol in rice. A complete separation of all compounds was achieved within 25 min using an Inertsil CN-3, SIL-100A 5 μM (4.6 mm × 250 mm) column and an isocratic elution system of hexane/isopropanol/ethylacetate/acetic acid (97.6:0.8:0.8:0.8, v/v/v/v) at a flow rate varying from 0.7 to 1.5 mL min(-1). A linear correlation coefficient (r(2)>0.99) and high reproducibility were obtained at concentrations ranging 0.05-10 μg mL(-1) for vitamin E isomers and 0.5-500 μg mL(-1) for γ-oryzanol. This method proved to be rapid, accurate and reproducible. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. A new liquid chromatographic method for routine determination of oxytetracycline marker residue in the edible tissues of farm animals.

    PubMed

    Fletouris, Dimitrios J; Papapanagiotou, Elias P

    2008-06-01

    A simple, rapid, and specific ion-pair liquid chromatographic method for routine determination of the marker residue of oxytetracycline (OTC), namely OTC and 4-epi-oxytetracycline (4-epiOTC), in edible animal tissues (muscle, liver, kidney, and fat) has been developed. Minced tissue samples were acidified at pH 2.7 with 2 mol L(-1) sulfuric acid and extracted with acetonitrile. The extracts were purified by treatment with ammonium sulfate solution and concentrated into 0.1 mol L(-1) phosphoric acid. Baseline separation was carried out isocratically on a Nucleosil 100-5 C(18), 5-microm column using an acetonitrile-0.01 mol L(-1) disodium hydrogen phosphate (20:80, v/v) mobile phase that contained both positively (tetrabutylammonium) and negatively (octanesulfonate) charged pairing ions and EDTA, and was adjusted to pH 3.8. Detection was by UV at 370 nm. The method was fully validated according to Commission Decision 2002/657/EC. Overall recoveries were better than 82.6% and overall relative standard deviation was better than 6% for all the tissues examined. The good analytical characteristics of the method allowed limits of quantification as low as 30 ng g(-1) for muscle and fat and 50 ng g(-1) for liver and kidney, for both OTC and 4-epiOTC, to be realized. The method was successfully used to determine the OTC marker residue in tissues of two sheep intramuscularly administered a commercial OTC formulation.

  7. Simultaneous high-performance liquid chromatographic determination of puerarin, daidzin, paeoniflorin, liquiritin, cinnamic acid, cinnamaldehyde and glycyrrhizin in Kampo medicines.

    PubMed

    Okamura, N; Miki, H; Orii, H; Masaoka, Y; Yamashita, S; Kobayashi, H; Yagi, A

    1999-03-01

    We report a high-performance liquid chromatographic method to determine the quantities of puerarin, daidzin, paeoniflorin, liquiritin, cinnamic acid, cinnamaldehyde and glycyrrhizin in Kampo medicine. All seven compounds were separated in less than 30 min with a Wakosil-II 5C18 AR column by linear gradient elution using 0.01% (v/v) phosphoric acid acetonitrile (0 min 90:10, 10 min 88:12, 22 min 70:30, 30 min 30:70) as the mobile phase at a flow-rate of 1.0 ml/min(-1), and detection at 250 nm. The detection limits of these compounds are 0.15-0.3 microM with response linearity. This method was applied to determine the quantities in eight Kampo decoctions; Mao-to, Makyo-yokukan-to, Makyo-kanseki-to, Yokuinin-to, Sho-seiryu-to, Keima-kakuhan-to, Kakkon-to and Kakkon-to-ka-senkyu-sin'i. Glycyrrhizin content was lower in both the decoction and the methanol-diluted decoction of Sho-seiryu-to compared with the others. Low pH due to organic acids of Schisandrae fructus in the decoction caused inhibition for glycyrrhizin dissolution in Sho-seiryu-to.

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

    PubMed Central

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

    2015-01-01

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

  9. 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.

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

    PubMed

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

    1990-01-01

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

  11. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Concurrent high-performance liquid chromatographic measurement of loxapine and amoxapine and of their hydroxylated metabolites in plasma.

    PubMed

    Hüe, B; Palomba, B; Giacardy-Paty, M; Bottaï, T; Alric, R; Petit, P

    1998-06-01

    The dibenzoxazepine neuroleptic loxapine, its N-demethylated metabolite amoxapine, and their 7- and 8-hydroxymetabolites were measured simultaneously in plasma by reversed-phase high-performance chromatographic method. An original liquid-liquid extraction procedure was performed, consisting in coextraction of the substances together with a water-miscible solvent (acetonitrile) by a non-water-miscible solvent (toluene). The substances were separated on a 5-microm CN 25-cm column, and eluted with a mobile phase consisting of acetonitrile-acetic acid 0.5 N (30:70) and hexylamine (0.05%). They were detected by ultraviolet spectrophotometry at 310 nm. Clozapine was used as internal standard. Linearity was demonstrated in the range of 10 to 250 microg/l, and detection limits were found to be 3.5 to 6.3 microg/l according to the substance. Within-day repeatability ranged from 2.7% to 6.5%, and between-day reproducibility ranged from 0.9% to 20.2%. The extraction procedure provided a mean absolute recovery of 51.1% (range, 40.7% to 58.6%) with a mean coefficient of variation of 4.2%. This technique was applied to the concurrent determination of plasma concentrations of the compounds in 10 patients administered loxapine 75 to 600 mg daily. Steady state plasma levels of loxapine were significantly correlated with oral doses (n = 10, r = 0.858, p < 0.002). In conclusion, the method proved to be a convenient and reproducible procedure allowing the simultaneous measurement of loxapine, amoxapine, and their metabolites in patients.

  13. Improved high-performance liquid chromatographic analysis of terazosin in human plasma.

    PubMed

    Cheah, P Y; Yuen, K H; Liong, M L

    2000-08-18

    A simple, sensitive and reproducible high-performance liquid chromatography (HPLC) method was developed for the determination of terazosin in human plasma. The method involves a one-step single solvent extraction procedure using dichloromethane with a 0.25 ml plasma sample. Recovery values were all greater than 90% over the concentration range 0.25-100 ng/ml. Terazosin was found to adsorb to glass or plastic tubes, but this could be circumvented by using disposable plastic tubes. Also, rinsing the injector port with methanol after each injection helped to prevent any carry-over effect. The internal standard, prazosin, did not exhibit this problem. The method has a quantification limit of 0.25 ng/ml. The within- and between-day coefficient of variation and accuracy values were all less than 7% over the concentration range 0.25-100 ng/ml and hence the method is suitable for use in pharmacokinetic studies of terazosin.

  14. Robust isocratic liquid chromatographic separation of functional poly(methyl methacrylate).

    PubMed

    Jiang, Xulin; Lima, Vincent; Schoenmakers, Peter J

    2003-11-07

    The separation of telechelic poly(methyl methacrylate) (PMMA) prepolymers based on the number of end-groups under critical liquid chromatography (LC) conditions has been studied using a bare-silica column, which can interact with polar functional groups. The critical solvent compositions for non-functional, mono-functional and bi-functional PMMAs were determined in normal-phase LC using mixtures of acetonitrile and dichloromethane (DCM) of varying composition as the mobile phase. The telechelic prepolymers were successfully separated according to hydroxyl (OH) functionality (with zero, one, or two OH groups, respectively) under the critical conditions, in which fast (5 min), base-line separations were obtained independent of molecular weight. Changing the column temperature, flow rate, and mobile-phase composition within a certain range did not affect the functionality separation. Therefore this isocratic LC separation method is quite robust. Evaporative light-scattering detector (ELSD) calibration curves were used for the quantitative analysis of functional PMMA prepolymers.

  15. High-pressure liquid chromatographic analysis of diazepam, oxazepam and N-desmethyldiazepam in human blood.

    PubMed

    Kabra, P M; Stevens, G L; Marton, L J

    1978-03-21

    We describe a rapid method for precisely measuring concentrations of diazepam, oxazepam and N-desmethyldiazepam in blood by high-pressure liquid chromatography. The drugs, together with an internal standard, prazepam, are extracted from 2 ml of blood and analyzed isocratically on a reversed-phase column with a mobile phase consisting of acetonitrile-0.01 M sodium acetate buffer (35:65 v/v). The eluted drugs are detected by their absorption at 240 nm. The sensitivity of this method is 30 microgram/l for oxazepam and N-desmethyldiazepam, 40 microgram/l for diazapam, for 2-ml blood samples. Relative recovery of added drugs to blood varies from 91 to 110%. The day-to-day precision (coefficient of variation) established by 10 replicate analyses was 2.8 to 9.6%.

  16. High-performance liquid chromatographic determination of cortolic and cortolonic acids as pyrenyl ester derivatives.

    PubMed

    Iohan, F; Vincze, I; Monder, C; Cohen, S

    1991-03-08

    A new procedure is described for the detection of the acidic metabolites of cortisol (cortoic acids) as the pyrenylmethyl-21-oic esters. The derivatizing reagent, diazomethylpyrene, was prepared by an improved procedure. The reagent was used at room temperature, required no catalyst, and was not restricted by stoichiometric requirements. The steroid esters were separated by reversed-phase high-performance liquid chromatography and analyzed simultaneously by their ultraviolet absorbance and fluorescence characteristics. Identities of the products were confirmed using the photodiode array detector to determine spectral profiles, absorbance maxima, and absorbance ratios. Further confirmation of identity of the cortoic acid esters used mass spectrometry under normal and collision-activated dissociation conditions. With the method described, a linear spectral response was obtained between 8 and 1680 fmol. Application of the technique to the analysis of steroid acids in human urine indicated the presence of cortoic acids.

  17. Electrochemically modulated liquid chromatographic separation of triazines and the effect of pH on retention.

    PubMed

    Yakes, Betsy Jean; Keller, David W; Porter, Marc D

    2010-06-25

    Electrochemically modulated liquid chromatography (EMLC) manipulates analyte retention by changing the potential applied (E(app)) to a conductive stationary phase. This paper applies EMLC to the separation of a set of seven triazines which are commonly used but environmentally hazardous herbicides. Experiments herein examine the influence of E(app) and the pH of the mobile phase on triazine retention. The results are discussed in terms of: (1) retention of triazines of dissimilar acid strengths and by correlations with the pH of the mobile phase; (2) how changes in E(app) and acid-base equilibria modulate elution; (3) qualitative insights into EMLC-based retention; and (4) potential merits of EMLC in realizing the rapid separation of the seven-component triazine mixture.

  18. 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.

  19. 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.

  20. Liquid chromatographic determination of nine N-methylcarbamates in drinking water.

    PubMed

    Morrica, Patrizia; Fidente, Paola; Seccia, Serenella

    2005-01-01

    A multi-residue method for the simultaneous extraction from drinking water using solid-phase extraction on LiChrolut EN [poly(styrene-divinylbenzene), PSDVB] and determination of nine N-methylcarbamate pesticides (NMCs) (aldicarb, its metabolites i.e. aldicarb sulfone and aldicarb sulfoxide and carbaryl, carbofuran, dioxacarb, ethiofencarb, methomyl and propoxur) using reversed-phase liquid chromatography was studied. A 1000-fold pre-concentration was achieved and the method was used for determination of the nine pesticides in water, with limits of detection in the range 3-15 ng L(-1). For all compounds the recoveries determined at the 0.1 and 1 microg L(-1) level generally ranged from 85 to 104% with relative standard deviations (RSD) of 1.4-8.8%.

  1. High-performance liquid chromatographic determination of N-alpha-acetyl-L-carnosine in equine plasma.

    PubMed

    Dunnett, M

    1997-01-10

    N-alpha-Acetyl-L-carnosine (NAcCAR) in perchloric acid extracts of equine plasma was assayed by high-performance liquid chromatography on a 3 microns Hypersil ODS (150 x 4.6 mm I.D.) column eluted with 5 mM phosphoric acid-1 mM triethylamine, pH 2.58. NAcCAR was isolated by solid-phase extraction on Isolute PRS (propylsulphonyl) columns. The HPLC mean retention time for NAcCAR was 5.9 +/- 0.2 min. The recovery from plasma by solid-phase extraction was 93.9-99.7% and lower limit of detection in plasma was 0.18 microM. The normal NAcCAR concentration in equine plasma was 2.4 +/- 0.3 microM. The method was applied to the determination of plasma concentrations following oral and intravenous NAcCAR administration.

  2. Rigorous evaluation of chemical measurement uncertainty: liquid chromatographic analysis methods using detector response factor calibration

    NASA Astrophysics Data System (ADS)

    Toman, Blaza; Nelson, Michael A.; Bedner, Mary

    2017-06-01

    Chemical measurement methods are designed to promote accurate knowledge of a measurand or system. As such, these methods often allow elicitation of latent sources of variability and correlation in experimental data. They typically implement measurement equations that support quantification of effects associated with calibration standards and other known or observed parametric variables. Additionally, multiple samples and calibrants are usually analyzed to assess accuracy of the measurement procedure and repeatability by the analyst. Thus, a realistic assessment of uncertainty for most chemical measurement methods is not purely bottom-up (based on the measurement equation) or top-down (based on the experimental design), but inherently contains elements of both. Confidence in results must be rigorously evaluated for the sources of variability in all of the bottom-up and top-down elements. This type of analysis presents unique challenges due to various statistical correlations among the outputs of measurement equations. One approach is to use a Bayesian hierarchical (BH) model which is intrinsically rigorous, thus making it a straightforward method for use with complex experimental designs, particularly when correlations among data are numerous and difficult to elucidate or explicitly quantify. In simpler cases, careful analysis using GUM Supplement 1 (MC) methods augmented with random effects meta analysis yields similar results to a full BH model analysis. In this article we describe both approaches to rigorous uncertainty evaluation using as examples measurements of 25-hydroxyvitamin D3 in solution reference materials via liquid chromatography with UV absorbance detection (LC-UV) and liquid chromatography mass spectrometric detection using isotope dilution (LC-IDMS).

  3. A high-performance liquid chromatographic method for determination of the niguldipine analogue DHP-014.

    PubMed

    Zhou, Xiao-fei; Wang, Qi; Coburn, Robert A; Morris, Marilyn E

    2006-01-01

    A simple and reliable reversed-phase high-performance liquid chromatography method was developed and validated for the determination of DHP-014, a niguldipine analogue with potent P-glycoprotein inhibitory and negligible calcium channel blocking properties, in rat plasma. DHP-014 and niguldipine hydrochloride (the internal standard) were extracted from rat plasma by liquid extraction using hexane. DHP-014 was then separated by HPLC on a C18 column and quantified by ultraviolet detection at 238 nm. The mobile phase consisted of acetonitrile-aqueous 5 mM phosphate buffer (65:35, v/v) containing 0.4% (v/v) triethylamine adjusted to pH 7.0. The mean extraction efficiency of DHP-014 was 109.0 +/- 12.9, 97.7 +/- 8.0 and 102.9 +/- 7.5% for DHP-014 concentrations of 10, 50 and 100 nM, respectively (n = 5). The method was linear over the concentration range 2.5-200 nM with a regression coefficient of 0.998. The limit of detection of DHP-014 in rat plasma was 1.0 nM. The intra- and inter-day coefficients of variation for DHP-014 in rat plasma were 4.7-7.9 and 6.9-9.9%, respectively. The intra- and inter-day accuracy was 98.2-99.5 and 97.9-103%, respectively. The bioanalytical technique was used to determine DHP-014 in plasma samples in a pharmacokinetic study of DHP-014 administered to female Sprague-Dawley rats. Copyright 2005 John Wiley & Sons, Ltd.

  4. Rigorous evaluation of chemical measurement uncertainty: Liquid chromatographic analysis methods using detector response factor calibration.

    PubMed

    Toman, Blaza; Nelson, Michael A; Bedner, Mary

    2017-06-01

    Chemical measurement methods are designed to promote accurate knowledge of a measurand or system. As such, these methods often allow elicitation of latent sources of variability and correlation in experimental data. They typically implement measurement equations that support quantification of effects associated with calibration standards and other known or observed parametric variables. Additionally, multiple samples and calibrants are usually analyzed to assess accuracy of the measurement procedure and repeatability by the analyst. Thus, a realistic assessment of uncertainty for most chemical measurement methods is not purely bottom-up (based on the measurement equation) or top-down (based on the experimental design), but inherently contains elements of both. Confidence in results must be rigorously evaluated for the sources of variability in all of the bottom-up and top-down elements. This type of analysis presents unique challenges due to various statistical correlations among the outputs of measurement equations. One approach is to use a Bayesian hierarchical (BH) model which is intrinsically rigorous, thus making it a straightforward method for use with complex experimental designs, particularly when correlations among data are numerous and difficult to elucidate or explicitly quantify. In simpler cases, careful analysis using GUM Supplement 1 (MC) methods augmented with random effects meta analysis yields similar results to a full BH model analysis. In this article we describe both approaches to rigorous uncertainty evaluation using as examples measurements of 25-hydroxyvitamin D3 in solution reference materials via liquid chromatography with UV absorbance detection (LC-UV) and liquid chromatography mass spectrometric detection using isotope dilution (LC-IDMS).

  5. Analysis of Metribuzin and transformation products in soil by pressurized liquid extraction and liquid chromatographic-tandem mass spectrometry.

    PubMed

    Henriksen, Trine; Svensmark, Bo; Juhler, René K

    2002-05-24

    A method developed for study of metribuzin degradation in soil is presented. LC-MS-MS and electrospray ionisation was used for analysis of metribuzin and the metabolites deaminometribuzin (DA), diketometribuzin (DK) and deaminodiketometribuzin (DADK). Soil samples were extracted by pressurized liquid extraction using methanol-water (75:25) at 60 degrees C. In general, recoveries were about 75% for metribuzin, DA and DADK and their detection limit in soil was 1.25 microg/kg. Lower sensitivity was observed for DK, with detection limit at 12.5 microg/kg and recovery about 50%.

  6. 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)

  7. Liquid chromatographic determination of aflatoxins, ochratoxin A, and zearalenone in grains, oilseeds, and animal feeds by post-column derivatization and on-line sample cleanup.

    PubMed

    Chamkasem, N; Cobb, W Y; Latimer, G W; Salinas, C; Clement, B A

    1989-01-01

    A liquid chromatographic method using on-line sample cleanup, reverse flow analytical column loading, gradient elution, and postcolumn derivatization with iodine permits direct, rapid determination of aflatoxins B1, B2, G1, and G2, as well as ochratoxin A and zearalenone. Limits of quantitation are 5 ppb for the aflatoxins and ochratoxin A and 30 ppb for zearalenone. This procedure performs well as a multimycotoxin screen for cereal grains and oilseeds, with more limited success in complete animal feeds.

  8. 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

  9. Chromatographic performance of large-pore versus small-pore columns in micellar liquid chromatography.

    PubMed

    McCormick, Timothy J; Foley, Joe P; Lloyd, David K

    2003-02-25

    Micellar liquid chromatography (MLC) is useful in bioanalysis because proteinaceous biofluids can be directly injected onto the column. The technique has been limited in part because of the apparently weak eluting power of micellar mobile phases. It has recently been shown [Anal. Chem. 72 (2000) 294] that this may be overcome by the use of large pore size stationary phases. In this work, large-pore (1000 A) C(18) stationary phases were evaluated relative to conventional small-pore (100 A) C(18) stationary phases for the direct sample injection of drugs in plasma. Furthermore, the difference between the large and small pore phases in gradient elution separations of mixtures of widely varying hydrophobicities was investigated. Large-pore stationary phases were found to be very effective for eluting moderately to highly hydrophobic compounds such as ibuprofen, crotamiton, propranolol, and dodecanophenone, which were highly retained on the small-pore stationary phases typically used in MLC. The advantages of direct introduction of biological samples (drugs in plasma) and rapid column re-equilibration after gradient elution in MLC were maintained with large-pore phases. Finally, recoveries, precision, linearity, and detection limits for the determination of quinidine and DPC 961 in spiked bovine plasma were somewhat better using MLC with wide pore phases.

  10. 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

    2016-06-07

    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.

  11. New high-performance liquid chromatographic method for plasma/serum analysis of lamotrigine.

    PubMed

    Croci, D; Salmaggi, A; de Grazia, U; Bernardi, G

    2001-12-01

    Lamotrigine is an anticonvulsant drug recently approved in Italy for clinical use. Therapeutic monitoring of lamotrigine is relevant for patient management and avoidance of toxicity. The authors describe a simple, sensitive, and highly selective high-performance liquid chromatography method that does not involved extraction for analysis of serum lamotrigine. Serum (20 microL) with internal standard (BW 725 C) was injected directly into a column (25 cm x 4.6 mm) with an internal surface reversed phase (ISRP). The mobile phase consisted of 0.01 mol/L potassium phosphate bibasic (pH 6.0) and acetonitrile (82:18), the flow rate was 1.0 mL/min, and UV detection was optimized at 330 nm. The overall between-run coefficient of variance ranged from 1.89% to 3.25% and the lowest limit of detection was 0.05 mg/L. High linearity (r = 0.9996) in a wide range of concentrations (0.1-20.0 mg/L) and no interference with other antiepileptic drugs, benzodiazepines, and tricyclic antidepressants were the other characteristics of the method. The innovation of this method is the use of ISRP column and the choice of detection wavelength, which allow a shorter analysis time (5-6 minutes). The possibility of direct injection of plasma samples into the column permits a reduction in reagent consumption and in analytic steps, and hence in analytic error.

  12. High performance liquid chromatographic determination of cox-2 inhibitor rofecoxib in human plasma.

    PubMed

    Mandal, U; Ganesan, M; Jayakumar, M; Pal, T K; Chattaraj, T K; Ray, Krishnangshu; Banerjee, S N

    2003-08-01

    A convenient, sensitive and simple method for the determination of rofecoxib in human plasma is presented. The analytical technique is based on reversed phase high performance liquid chromatography coupled with UV detector (Knauer, Germany) set at 272 nm. The retention time of rofecoxib after recovery from plasma, was 8.9 minutes. The method has been validated over a linear range of 50-450 ng/ml from plasma. After validation the method was used to study the pharmacokinetic profile of rofecoxib in 6 healthy volunteers as per DCGI guidelines after administration of a single oral dose (50 mg). The extraction efficiency from plasma varied from 93.95-99.58%. The minimum quantifiable concentration was set at 50 ng/ml (% CV < 10%). The pharmacokinetic parameters were Cmax = 318.58 +/- 30.65 ng/ml at tmax = 2.66 +/- 0.25 hours, AUC0-t = 4007.88 +/- 438.32 ng hour/ml, AUC0-yen = 5454.66 +/- 822.29 ng hour/ml, Kel = 0.0433 +/- 0.0067/hour, and t1/2 = 16.36 +/- 2.89 hours.

  13. High-performance liquid chromatographic assay for metamizol metabolites in rat plasma: application to pharmacokinetic studies.

    PubMed

    Domínguez-Ramírez, Adriana Miriam; Calzadilla, Patricia Carrillo; Cortés-Arroyo, Alma Rosa; Hurtado Y de la Peña, Marcela; López, José Raúl Medina; Gómez-Hernández, Martín; López-Muñoz, Francisco Javier

    2012-12-01

    In order to evaluate the pharmacokinetics of metamizol in the presence of morphine in arthritic rats, after subcutaneous administration of the drugs, an easy, rapid, sensitive and selective analytical method was proposed and validated. The four main metamizol metabolites (4-methylaminoantipyrine, 4-aminoantipyrine, 4-acetylaminoantipyrine and 4-formylaminoantipyrine) were extracted from plasma samples (50-100μl) by a single solid-phase extraction method prior to reverse-phase high performance liquid chromatography with diode-array detection. Standard calibration graphs for all metabolites were linear within a range of 1-100μg/ml (r(2)≥0.99). The intra-day coefficients of variation (CV) were in the range of 1.3-8.4% and the inter-day CV ranged from 1.5 to 8.4%. The intra-day assay accuracy was in the range of 0.6-9.6% and the inter-day assay accuracy ranged from 0.9 to 7.5% of relative error. The lower limit of quantification was 1μg/ml for all metabolites using a plasma sample of 100μl. Plasma samples were stable at least for 4 weeks at -20°C. This method was found to be suitable for studying metamizol metabolites pharmacokinetics in arthritic rats, after simultaneous administration of metamizol and morphine, in single dose. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. 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. © 2014 Institute of Food Technologists®

  15. [Determination of fluoxastrobin and fluacrypyrim residues in fruits and beverages by ultra performance liquid chromatograph].

    PubMed

    Luo, Lili; Bo, Haibo; Bi, Yang; Wu, Yonglong

    2009-03-01

    A method was developed for the determination of fluoxastrobin and fluacrypyrim residues in fruits and beverages by ultra performance liquid chromatography with photo-diode array (UPLC-PDA) detection. The sample was extracted with ethyl acetate-cyclohexane (1:1, v/v) by ultrasonic, cleaned-up by gel permeation chromatography (GPC), and then determined by UPLC-PDA. The quantification was performed by external standard. A BEH C18 colunm (50 mm x 2.1 mm, 1.7 microm) was used, and water-acetonitrile (3:7, v/v) was used as mobile phase at a flow rate of 0.3 mL/min. The column temperature was set at 40 degrees C, and ultraviolet absorption wavelength was set at 251 nm. The calibration curves were linear between the peak area and the concentration in the range of 0.05-2 mg/L for fluoxastrobin and fluacrypyrim, the correlation coefficients were greater than 0.999. The average recoveries spiked in fruit and beverage matrices at the three concentration levels of 0.01, 0.05, 0.1 mg/kg ranged from 82.60% to 101.11% with the relative standard deviations of 5.4%-15.3%. The limits of detection (LOD) were not greater than 6 microg/kg and the limits of quantification (LOQ) were not greater than 20 microg/kg in fruit and beverage matrices for fluoxastrobin and fluacrypyrim.

  16. Ion-pair reverse-phase liquid chromatographic determination of amprolium in complete feeds and premixes.

    PubMed

    Kentzer, E J; Cottingham, L S; Smallidge, R L

    1988-01-01

    Amprolium is extracted with methanol-water (2 + 1) containing 5mM dioctylsulfosuccinate (DOSS) and 10mM CaCl2. The analyte is separated from coextracted materials by isocratic ion-pair reverse-phase liquid chromatography, following removal of late-eluting materials on an acid alumina cleanup column, and is detected at 270 nm. The mobile phase contains 4mM DOSS with 0.3% diethylamine and 1% acetic acid in 40% acetonitrile. Linearity is satisfactory over the range of 2.5-50 micrograms/mL. Mean recovery, as determined by standard addition to commercial samples, is 100.1%. Accuracy was further tested in studies comparing the LC method to the official AOAC colorimetric method, using commercial samples, and was found to be satisfactory. Studies show that common poultry feed additives, grass meals, and some pelletization aids do not interfere with the analysis; however, when bentonite is present, recovery is decreased. The precision of the method, measured over several experiments on commercial samples, is satisfactory as indicated by coefficients of variation ranging from less than 1 to 4.5. A ruggedness test resulted in an overall CV of 3.2%, indicating the probable success of the method in a collaborative study.

  17. 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

  18. 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.

  19. 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.

  20. 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. © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  1. Ultra-Performance Liquid Chromatographic Determination of Tocopherols and Retinol in Human Plasma

    PubMed Central

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

    2014-01-01

    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. PMID:24170122

  2. High-performance liquid chromatographic assay of human red blood cell thiopurine methyltransferase activity.

    PubMed

    Lennard, L; Singleton, H J

    1994-11-04

    An assay is described for the determination of red blood cell (RBC) thiopurine methyltransferase (TPMT) activity. TPMT S-methylates the antileukaemic drugs 6-mercaptopurine (6-MP) and 6-thioguanine and enzyme activity is inherited as a genetic trait. The assay is based on the TPMT-catalysed conversion of 6-MP to 6-methylmercaptopurine (methyl-MP) with non-radioactive S-adenosyl-L-methionine as the methyl donor. The methyl-MP metabolite is extracted into toluene as a phenyl-mercury adduct and back-extracted into 0.1 M HCl. Methyl-MP is quantitated by reversed-phase high-performance liquid chromatography (HPLC) with ultraviolet detection using a C18 Resolve cartridge and a mobile phase of methanol-water (20:80, v/v) with 100 mM triethylamine adjusted to pH 3.2 with orthophosphoric acid. There was a strong correlation between the HPLC assay and the established radiochemical assay (P < 0.0001). TPMT activities were measured by both methods in a population study of 111 children. There was no significant difference between the two frequency distribution histograms (P > 0.6).

  3. 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.

  4. Calculation of retention time tolerance windows with absolute confidence from shared liquid chromatographic retention data.

    PubMed

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

    2015-09-18

    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.

  5. Enantioselective high-performance liquid chromatographic determination of nicardipine in human plasma.

    PubMed

    Uno, T; Ohkubo, T; Sugawara, K

    1997-09-26

    A sensitive method for the enantioselective high-performance liquid chromatography (HPLC) determination of nicardipine in human plasma is described. (+)-Nicardipine, (-)-nicardipine and (+)-barnidipine as an internal standard are detected by an ultraviolet detector at 254 nm. Racemic nicardipine in human plasma was extracted by a rapid and simple procedure based on C18 bonded-phase extraction. The extraction samples were purified and concentrated on a pre-column using a C1 stationary phase and the enantiomers of nicardipine are quantitatively separated by HPLC on a Sumichiral OA-4500 column, containing a chemically modified Pirkle-type stationary phase. Determination of (+)- and (-)-nicardipine was possible in a concentration range of 5-100 ng ml(-1) and the limit of detection in plasma was 2.5 ng ml(-1). The recoveries of (+)- and (-)-nicardipine added to plasma were 91.4-98.4% and 93.3-96.7%, respectively, with coefficients of variation of less than 9.0 and 9.4% respectively. The method was applied to low level monitoring of (+)- and (-)-nicardipine in plasma from healthy volunteers.

  6. Rapid extraction and high-performance liquid chromatographic determination of parthenolide in feverfew (Tanacetum parthenium).

    PubMed

    Zhou, J Z; Kou, X; Stevenson, D

    1999-03-01

    A rapid and sensitive method for quantifying parthenolide in feverfew herb (Tanacetum parthenium) was developed that is significantly faster than those reported in the literature. The extraction system consisted of acetonitrile/water (90:10, v/v) in a bottle with stirring for 30 min. Both Soxhlet and bottle-stirring extractions were studied. Samples were analyzed using high-performance liquid chromatography with a Cosmosil C18-AR column (150 x 4.6 mm, 5 microm, 120 A). The mobile phase consisted of acetonitrile/water (55:45, v/v) with a flow rate of 1.5 mL/min and UV detection at 210 nm. Analysis time was 6 min, with a detection limit of 0.10 ng on column. The calibration curve was linear over a range of 0.160-850 microg/mL parthenolide with R(2) = 0.9999. Replicate tests indicated good reproducibility of the method with an RSD% = 0.88 (n = 10). Spike recovery of parthenolide was found to be 99.3% with an RSD% = 1.6 (n = 6).

  7. 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

  8. Fractionation of complex protein mixture by virtual three-dimensional liquid chromatography based on combined pH and salt steps.

    PubMed

    Ning, Zhi-Bin; Li, Qing-Run; Dai, Jie; Li, Rong-Xia; Shieh, Chia-Hui; Zeng, Rong

    2008-10-01

    The complexity and diversity of biological samples in proteomics require intensive fractionation ahead of mass spectrometry identification. This work developed a chromatographic method called virtual three-dimensional chromatography to fractionate complex protein mixtures. By alternate elution with different pHs and salt concentrations, we implemented pH and salt steps by turns on a single strong cation exchange column to fully exploit its chromatographic ability. Given standard proteins that were not resolved solely by pH or salt gradient elution could be successfully separated using this combined mode. With a reversed phase column tandem connected behind, we further fractionated as well as desalted proteins as the third dimension. This present strategy could readily be adapted with respect to special complexity of biological samples. Crude plasma without depleting high abundance proteins were fractionated by this three-dimensional mode and then analyzed by reversed phase liquid chromatography coupled with LTQ mass spectrometry. In total, 1933 protein groups with wide dynamic ranges were identified from a single experiment. Some characteristics that correlated to the behavior of proteins on strong cation exchange columns are also discussed.

  9. Biogas production from the mechanically pretreated, liquid fraction of sorted organic municipal solid wastes.

    PubMed

    Alvarado-Lassman, A; Méndez-Contreras, J M; Martínez-Sibaja, A; Rosas-Mendoza, E S; Vallejo-Cantú, N A

    2017-06-01

    The high liquid content in fruit and vegetable wastes makes it convenient to mechanically separate these wastes into mostly liquid and solid fractions by means of pretreatment. Then, the liquid fraction can be treated using a high-rate anaerobic biofilm reactor to produce biogas, simultaneously reducing the amount of solids that must be landfilled. In this work, the specific composition of municipal solid waste (MSW) in a public market was determined; then, the sorted organic fraction of municipal solid waste was treated mechanically to separate and characterize the mostly liquid and solid fractions. Then, the mesophilic anaerobic digestion for biogas production of the first fraction was evaluated. The anaerobic digestion resulted in a reduced hydraulic retention time of two days with high removal of chemical oxygen demand, that is, 88% on average, with the additional benefit of reducing the mass of the solids that had to be landfilled by about 80%.

  10. Dissolution and fractionation of nut shells in ionic liquids.

    PubMed

    Carneiro, Aristides P; Rodríguez, Oscar; Macedo, Eugénia A

    2017-03-01

    The aim of this work was to study the dissolution of raw peanut and chestnut shells in ionic liquids. Dissolution of raw biomass up to 7wt% was achieved under optimized operatory conditions. Quantification of polysaccharides dissolved through quantitative (13)Cq NMR revealed extractions of the cellulosic material to ionic liquids as high as 87%. Regeneration experiments using an antisolvent mixture allowed to recover the cellulosic material and the ionic liquid. The overall mass balance presented very low loss rates (<8%), recoveries of 75% and 95% of cellulosic material from peanut and chestnut shells, respectively, and the recovery of more than 95% of the ionic liquid in both cases. These results show the high potential of using nut shells and ionic liquids for biorefining purposes. Moreover, high recovery of ionic liquids favors the process from an economical point of view.

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

    PubMed

    El-Saharty, Yasser Shaker Ibrahim

    2008-01-01

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

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

    SciTech Connect

    Kwon, K.C.

    1996-03-01

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

  13. Liquid chromatographic study of the enzymatic degradation of endomorphins, with identification by electrospray ionization mass spectrometry.

    PubMed

    Péter, A; Tóth, G; Tömböly, C; Laus, G; Tourwè, D

    1999-06-18

    The recently discovered native endomorphins play an important role in opioid analgesia, but their metabolic fate in the organism remains relatively little known. This paper describes the application of high-performance liquid chromatography combined with electrospray ionization mass spectrometry to identify the degradation products resulting from the incubation of endomorphins with proteolytic enzymes. The native endomorphin-1, H-Tyr-Pro-Trp-Phe-NH2 (1), and endomorphin-2, H-Tyr-Pro-Phe-Phe-NH2 (2), and an analog of endomorphin-2, H-Tyr-Pro-Phe-Phe-OH (3), were synthetized, and the levels of their resistance against carboxypeptidase A, carboxypeptidase Y, aminopeptidase M and proteinase A were determined. The patterns of peptide metabolites identified by this method indicated that carboxypeptidase Y first hydrolyzes the C-terminal amide group to a carboxy group, and then splits the peptides at the Trp3-Phe4 or Phe3-Phe4 bond. The remaining fragment peptides are stable against the enzymes investigated. Carboxypeptidase A degrades only analog 3 at the Phe3-Phe4 bond. Aminopeptidase M cleaves the peptides at the Pro2-Trp3 or Pro2-Phe3 bond. The C-terminal fragments hydrolyze further, giving amino acids and Phe-NH2-s while the N-terminal part displays a resistance to further aminopeptidase M digestion. Proteinase A exhibits a similar effect to carboxypeptidase Y: the C-terminal amide group is first converted to a carboxy group, and one amino acid is then split off from the C-terminal side.

  14. High-performance liquid chromatographic analysis of as-synthesised N,N'-dimethylformamide-stabilised gold nanoclusters product

    NASA Astrophysics Data System (ADS)

    Xie, Shunping; Paau, Man Chin; Zhang, Yan; Shuang, Shaomin; Chan, Wan; Choi, Martin M. F.

    2012-08-01

    Reverse-phase high-performance liquid chromatographic (RP-HPLC) separation and analysis of polydisperse water-soluble gold nanoclusters (AuNCs) stabilised with N,N'-dimethylformamide (DMF) were investigated. Under optimal elution gradient conditions, the separation of DMF-AuNCs was monitored by absorption and fluorescence spectroscopy. The UV-vis spectral characteristics of the separated DMF-AuNCs have been captured and they do not possess distinct surface plasmon resonance bands, indicating that all DMF-AuNCs are small AuNCs. The photoluminescence emission spectra of the separated DMF-AuNCs are in the blue-light region. Moreover, cationic DMF-AuNCs are for the first time identified by ion chromatography. Our proposed RP-HPLC methodology has been successfully applied to separate AuNCs of various Au atoms as well as DMF-stabilised ligands. Finally, the composition of the separated DMF-AuNCs was confirmed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry and electrospray ionisation mass spectrometry, proving that the as-synthesised DMF-AuNCs product consists of Au10+, Au10, Au11, Au12, Au13, and Au14 NCs stabilised with various numbers of DMF ligands.Reverse-phase high-performance liquid chromatographic (RP-HPLC) separation and analysis of polydisperse water-soluble gold nanoclusters (AuNCs) stabilised with N,N'-dimethylformamide (DMF) were investigated. Under optimal elution gradient conditions, the separation of DMF-AuNCs was monitored by absorption and fluorescence spectroscopy. The UV-vis spectral characteristics of the separated DMF-AuNCs have been captured and they do not possess distinct surface plasmon resonance bands, indicating that all DMF-AuNCs are small AuNCs. The photoluminescence emission spectra of the separated DMF-AuNCs are in the blue-light region. Moreover, cationic DMF-AuNCs are for the first time identified by ion chromatography. Our proposed RP-HPLC methodology has been successfully applied to separate AuNCs of

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

    PubMed

    Thongchai, Wisanu; Liawruangrath, Boonsom; Liawruangrath, Saisunee

    2007-01-01

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

  16. 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.

  17. Reductive amination of glutaraldehyde 2,4-dinitrophenylhydrazone using 2-picoline borane and high-performance liquid chromatographic analysis.

    PubMed

    Uchiyama, Shigehisa; Sakamoto, Hironari; Ohno, Akiko; Inaba, Yohei; Nakagome, Hideki; Kunugita, Naoki

    2012-09-21

    A typical method for the measurement of glutaraldehyde (GLA) employs 2,4-dinitrophenylhydrazine (DNPH) to form GLA-DNPhydrazone derivatives. However, this method is subject to analytical errors because GLA-DNPhydrazone is a quaternary bis-derivative and forms three geometric isomers (E-E, E-Z and Z-Z) as a result of the two C[double bond, length as m-dash]N double bonds. To overcome this issue, a method for transforming the C[double bond, length as m-dash]N double bond into a C-N single bond, using reductive amination of DNPhydrazone derivatives, has been applied. The amination reaction of GLA-DNPhydrazones with 2-picoline borane is accelerated with catalytic amounts of acid and is completed within 10 minutes in the presence of 100 mmol L(-1) phosphoric acid. Reduction of GLA-DNPhydrazone by 2-picoline borane is unique and results in the formation of N-(2,4-dinitrophenyl)-1-piperidinamine (DNPPA). NMR and LC-APCI-MS data confirmed the product identification. DNPPA is very stable and did not change when stored for at least four weeks at room temperature. DNPPA has excellent solubility of 14.6 g L(-1) at 20 °C in acetonitrile. The absorption maximum wavelength and the molar absorptivity of DNPPA were 351 nm and 4.2 × 10(4) L mol(-1) cm(-1) respectively. Complete separation between the reduced forms of C1-C10 aldehyde DNPhydrazones, including DNPPA, can be achieved by operating the reversed-phase high-performance liquid chromatograph at 351 nm in gradient mode using a C18 amide column. The reductive amination method for GLA overcomes analytical errors caused by E-E, E-Z and Z-Z geometrical isomers.

  18. Liquid chromatographic determination of fumonisins B1, B2, and B3 in corn: AOAC-IUPAC Collaborative Study.

    PubMed

    Sydenham, E W; Shephard, G S; Thiel, P G; Stockenström, S; Snijman, P W; Van Schalkwyk, D J

    1996-01-01

    A liquid chromatographic (LC) method for simultaneous determination of fumonisins B1 (FB1), B2 (FB2), and B3 (FB3) in corn was subjected to a collaborative study involving 12 participants from 10 countries, in which the accuracy and reproducibility characteristics of the method were established. Mean analyte recoveries from corn ranged from 81.1 to 84.2% for FB1 (at a spiking range of 500 to 8000 ng/g), from 75.9 to 81.9% for FB2 (at a spiking range of 200 to 3200 ng/g), and from 75.8 to 86.8% for FB3 (at a spiking range of 100 to 1600 ng/g). The valid data were statistically evaluated after exclusion of outliers. Relative standard deviations for within-laboratory repeatability ranged from 5.8 to 13.2% for FB1, from 7.2 to 17.5% for FB2, and from 8.0 to 17.2% for FB3. Relative standard deviations for between-laboratory reproducibility varied from 13.9 to 22.2% for FB1, from 15.8 to 26.7% for FB2, and from 19.5 to 24.9% for FB3. HORRAT ratios, calculated for the individual toxin analogues, ranged from 0.75 to 1.73. The LC method for determination of fumonisins B1, B2, and B3 in corn (at concentrations of 800-12800 ng total fumonisins/g) has been adopted by AOAC INTERNATIONAL.

  19. Analysis of essential oils and fragrances with a new generation of highly inert gas chromatographic columns coated with ionic liquids.

    PubMed

    Cagliero, Cecilia; Bicchi, Carlo; Cordero, Chiara; Liberto, Erica; Rubiolo, Patrizia; Sgorbini, Barbara

    2017-04-28

    In the fields of essential oils and fragrances, samples often consist of mixtures of compounds with similar structural and physical characteristics (e.g. mono- and sesquiterpenoids), whose correct identification closely depends on the synergic combination of chromatographic and mass spectral data. This sample complexity means that new GC stationary phases with different selectivities are continually being investigated. Ionic liquids (ILs) are of great interest as GC stationary phases in this field because of their selectivity (significantly different than that of currently phases) and their high temperature stability. A first generation of IL GC columns was found to be competitive when applied to these field, in terms of selectivity and efficiency, compared to conventional columns (polydimethylsiloxane, (e.g. OV-1), methyl-polysiloxane 5%-phenyl (e.g. SE-52), 7%-cyanopropyl, 7%-phenyl polysiloxane (e.g. OV-1701), and polyethylen glycol (e.g. PEG-20M). However, these columns showed significant activity towards polar or active analytes, which primarily affected their quantitative performance. A new generation of highly-inactive columns coated with three of the most widely-used ionic liquid GC stationary phases has recently been introduced; these phases are SLB-IL60i (1,12-di(tripropylphosphonium) dodecane bis(trifluoromethylsulfonyl) imide [NTf2], SLB-IL76i (tri-(tripropylphosphonium-hexanamido)-triethylamine [NTf2]), and SLB-IL111i (1,5-di (2,3-dimethyllimidazolium) pentane [NTf2]). This study carefully tested the new inert IL columns, in view of their routine application in the fragrance and essential oil fields. They were found to have unusually high selectivity, comparable to that of first-generation IL columns, while their inertness and efficiency were competitive with those of currently-used conventional columns. The IL column performance of first and second generations was compared, through the quali-quantitative analysis of components in a group of different

  20. Development of a liquid chromatographic method for the simultaneous quantification of curcumin, β-arteether, tetrahydrocurcumin and dihydroartemisinin. Application to lipid-based formulations.

    PubMed

    Memvanga, Patrick B; Mbinze, Jérémie K; Rozet, Eric; Hubert, Philippe; Préat, Véronique; Marini, Roland D

    2014-01-01

    A liquid chromatographic method was developed for the simultaneous separation of curcumin, β-arteether, tetrahydrocurcumin and dihydroartemisinin based on the design of experiments and the design space methodology. The influence of the percentage of organic modifier, flow rate of the mobile phase and column temperature on the analytes separation was investigated. The optimal chromatographic separation was achieved on a C18 column (125mm×4mm, 5μm) using an isocratic elution with a mobile phase consisting of methanol-ammonium acetate (pH 4; 10mM) (80:20, v/v) at a flow rate of 0.45ml/min and a column temperature of 32.5°C. This method was then validated for simultaneous quantification of curcumin and β-arteether contained in lipid-based formulations taking into account the β-expectation tolerance interval for the total error measurement. Finally, the suitability of the proposed liquid chromatographic method for routine analysis of curcumin and β-arteether loaded in lipid-based formulations has been proven.

  1. A new on-line, in-tube pre-column derivatization technique for high performance liquid chromatographic determination of azithromycin in human serum.

    PubMed

    Bahrami, Gholamreza; Mohammadi, Bahareh

    2006-01-18

    Pre-column derivatization methods for high performance liquid chromatographic assay of specific pharmaceutical agents using 9-fluorenylmethyl chloroformate (FMOC-Cl) have received special attention because highly fluorescent and stable adducts are provided by these methods. However, unlike the post-column on-line techniques, long derivatization time is needed and the reaction cannot be well controlled. A new, sensitive and fast pre-column on-line derivatization technique coupled with high-performance liquid chromatography using FMOC-Cl as labeling agent is described and validated for determination of azithromycin in human serum. After extraction of the drug from serum, the residue was reconstituted in mixture of acetonitrile-phosphate buffer (3:1, v/v; pH 8.5) and directly injected onto the chromatographic system. Continuous on-line derivatization and analysis of the compounds were successfully performed using in-tube elution of FMOC-Cl. The total time needed for derivatization and chromatographic analysis of the drug was 13 min. The assay was reliable and reproducible, with limit of quantification of 10 ng/ml. The described technique may offer significant advantages over existing off-line derivatization methods using FMOC-Cl.

  2. Spectral correlation of high-performance liquid chromatography-diode array detection data from two independent chromatographic runs peak tracking in pharmaceutical impurity profiling.

    PubMed

    Li, Wei; Hu, Chang-qin

    2008-05-09

    A novel qualitative analytical method for peak tracking in impurity profiling control by the correlation of spectra was established. Two-dimensional (2D) standard spectrochromatographic data produced by high-performance liquid chromatography with diode array detection (HPLC-DAD) were compared with sample data to develop two-dimensional chromatographic spectral correlative maps. Taking full advantage of separation efficiency of HPLC and spectral specificity of the analytes, the method was successfully used to recognize impurities in quinolone antibacterials, when in combination with relative retention times (RRTs). For the comparison of spectra was expanded to three-dimensional space, simultaneous identification of the chromatographic peaks can be obtained rapidly without preparation and injection of a reference solution, even when the mobile phase changed or the peaks of multi-component samples overlapped.

  3. Liquid chromatographic analysis of all-trans-retinyl palmitate, beta-carotene, and vitamin E in fortified foods and the extraction of encapsulated and nonencapsulated retinyl palmitate.

    PubMed

    Ye, L; Landen, W O; Eitenmiller, R R

    2000-09-01

    A liquid chromatographic method is described for the analysis of natural vitamin E homologues, all-rac-alpha-tocopheryl acetate, retinyl palmitate (encapsulated and nonencapsulated), and beta-carotene in various fortified foods. The vitamins are extracted in 2-propanol and hexane without saponification and quantitated by normal phase chromatography with fluorescence and visible detection. The sample components were identified using an on-line three-dimensional photodiode array detector, which permitted profiling of the 190-800 nm absorption spectrum of any chromatographic peak. The method showed linearity for the analytes in their respective calibration ranges. The percent recoveries for retinyl palmitate using starch- and gelatin-encapsulated standards were 101.0 +/- 1.0 and 100.1 +/- 0.9, respectively. The method measures six or more analytes in a single injection and differentiates between natural and synthetic forms of vitamin E.

  4. High-performance liquid chromatographic confirmation of cocaine and benzoylecgonine in biological samples using photodiode-array detection after toxicological screening.

    PubMed

    Balíková, M; Vecerková, J

    1994-06-03

    In the later stages after intake, the important markers of cocaine abuse are its main metabolites in urine, benzoylecgonine and ecgonine methyl ester. The efficiency of the extraction of amphoteric benzoylecgonine together with cocaine from aqueous media by means of various solvents at various pH values and by means of a mixed solid phase was tested. The extraction of benzoylecgonine with diethyl ether is not efficient, whereas chloroform, dichloromethane or mixed solid-phase extraction give satisfactory results. The analytical strategy for the general chromatographic screening and identification of unknown drugs in biological samples based on diethyl ether extraction was modified to permit the sensitive detection of cocaine abuse also on the basis of benzoylecgonine. A complementary high-performance liquid chromatographic method with photodiode-array detection after solid-phase extraction was introduced for specific confirmation and determination of cocaine and benzoylecgonine.

  5. Determination of scopoletin in rat plasma by high performance liquid chromatographic method with UV detection and its application to a pharmacokinetic study.

    PubMed

    Xia, Yufeng; Dai, Yue; Wang, Qiang; Liang, Huizheng

    2007-10-01

    A rapid and simple high-performance liquid chromatographic (HPLC) method has been developed and validated for determination of scopoletin in rat plasma using psoralen as internal standard. Chromatographic separation was achieved on a C(18) column using methanol and distilled water (49:51, v/v) containing 0.05% (v/v) phosphoric acid as mobile phase. The UV detector was set at 345 nm. The calibration curve was linear over the range of 0.165-9.90 microg/ml with a correlation coefficient of 0.9994. The recovery for plasma samples of 0.165, 1.32 and 6.60 microg/ml was 93.2%, 95.9% and 95.5%, respectively. The RSD of intra- and inter-day assay variations was less than 6.7%. This HPLC assay is a precise and reliable method for the analysis of scopoletin in pharmacokinetic studies.

  6. High-performance liquid chromatographic methods for the determination of the penems SCH 29482 and FCE 22101 in human serum and urine.

    PubMed

    Méndez, R; Negro, A; Martín-Villacorta, J

    1992-08-07

    High-performance liquid chromatographic methods have been developed for the determination of two 6-(1-hydroxyethyl)penems, SCH 29482 (I) and FCE 22101 (II), in serum and urine. Serum samples were combined with an equal volume of methanol to remove proteins and, after centrifugation, an aliquot of the supernatant was analysed by ion-pair chromatography on a reversed-phase C18 column with hexadecyltrimethylammonium bromide as the ion-pairing agent. The compounds were detected by their ultraviolet absorbance at 305 nm for II and 322 nm for I. Urine samples were diluted, filtered and analysed by the same chromatographic procedure. At concentrations of 1-500 micrograms/ml of each compound, the within- and between-day precisions were 1.8-3.6 and 2.6-5.1%, respectively. The detection limit was 0.2 micrograms/ml for I and 0.3 micrograms/ml for II.

  7. 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.

  8. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  10. Evaluation of a liquid chromatographic method for the determination of fumonisins in corn, poultry feed, and Fusarium culture material.

    PubMed

    Rice, L G; Ross, P F; Dejong, J; Plattner, R D; Coats, J R

    1995-01-01

    The performance of a liquid chromatographic method for determining fumonisins in corn, animal feeds, and culture material was evaluated. Efficiencies of extractions with the following solvent systems were determined: acetonitrile-water (50 + 50, v/v), methanol-water (75 + 25, v/v), and 100% water. The acetonitrile solvent gave both higher extraction efficiencies and faster extraction times than the other 2 solvents. Extraction was followed by C18 solid-phase extraction column cleanup. Fumonisin B1 (FB1), fumonisin B2 (FB2), and fumonisin B3 (FB3) were measured by precolumn derivatization with o-phthalaldehyde followed by isocratic separation on a C18 reversed-phase column with a mobile phase of 50 mM potassium dihydrogen phosphate (pH 3.3)-acetonitrile (60 + 40). Commercially prepared poultry feed, corn, and Fusarium spp. corn cultures were analyzed at the following levels: FB1, 1.5 to 15,000 micrograms/g; FB2, 0.5 to 4000 micrograms/g; FB3, and 0.17 to 1,500 micrograms/g. Recoveries were 91-94%, 90-100%, and 81-93% for FB1, FB2, and FB3, respectively. Precision (coefficient of variation) was determined with pooled field samples and ranged from 2% at 19 micrograms/g for FB1 to 9% at 0.17 microgram/g for FB3. Time and pH studies of the formation of the fluorescent derivative and its stability were conducted. Complete reaction occurred at pHs above 7.9, with optimal pH for chromatography between 8.0 and 8.5. No statistically significant response differences were detected for reaction times ranging from 4 to 40 min; however, the detector signal was significantly reduced when reaction times were shorter than 4 min. Chromatograms of samples were free of interferences for all feeds, corn, and culture material tested.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Iron isotope fractionation between liquid and vapor phases of iron pentacarbonyl.

    PubMed

    Wiesli, René A; Beard, Brian L; Braterman, Paul S; Johnson, Clark M; Saha, Susanta K; Sinha, Mahadeva P

    2007-01-15

    Iron isotope fractionation between liquid and vapor iron pentacarbonyl was measured in a closed system at approximately 0 and approximately 21 degrees C to determine if Fe isotope analysis of iron pentacarbonyl vapor is viable using electron-impact, gas-source mass spectrometry. At the 2sigma level, there is no significant Fe isotope fractionation between vapor and liquid under conditions thought to reflect equilibrium. Experiments at approximately 0 degrees C indicate iron pentacarbonyl vapor is approximately 0.05 per mil (per thousand) greater in (56)Fe/(54)Fe than liquid iron pentacarbonyl, which is just resolvable at the 1sigma level. Partial decomposition of iron pentacarbonyl vapor or liquid to an iron oxide or iron metal shows that significant isotopic fractionation occurs, where the decomposed product has a lower (56)Fe/(54)Fe ratio as compared to the starting iron pentacarbonyl. It follows that methods to decompose iron pentacarbonyl must be quantitative to obtain accurate isotope values.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  14. Solid-phase extraction for the high-performance liquid chromatographic determination of indomethacin, suxibuzone, phenylbutazone and oxyphenbutazone in plasma, avoiding degradation of compounds.

    PubMed

    Caturla, M C; Cusido, E

    1992-10-02

    A solid-phase extraction method was validated for the simultaneous high-performance liquid chromatographic determination of indomethacin, suxibuzone, phenylbutazone, oxyphenbutazone and their degradation products. Indomethacin was added as internal standard to plasma samples, which were then acidified with citrate buffer and passed through a phenyl cartridge. The drugs were eluted with hexane-diethyl ether (1:1, v/v), and the organic extract was taken to dryness. The residue was dissolved in methanol and chromatographed on a C18 column with ultraviolet detection at 240 nm. The elution was isocratic with a mobile phase of 0.02 M ammonium sulphate-acetonitrile (45:55, v/v), pH 3. For indomethacin, suxibuzone, phenylbutazone and oxyphenbutazone the limit of quantitation was 0.05 microgram/ml. The linearity was checked between 0.05 and 100 micrograms/ml (r = 0.999); within this range the recovery was higher than 90% and the accuracy showed relative errors of less than 7.5%. The main advantage of this method is the avoidance of degradation by using citrate buffer instead of the usual 5 M hydrochloric acid to acidify the plasma. The method is also more specific and less time-consuming than the previously reported liquid-liquid extraction, and could possibly be automated.

  15. 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.

  16. New simplified procedures for the extraction and simultaneous high-performance liquid chromatographic analysis of retinol, tocopherols and carotenoids in human serum.

    PubMed

    Barua, A B; Kostic, D; Olson, J A

    1993-08-11

    A short, simple extraction procedure and a sensitive reversed-phase high-performance liquid chromatographic assay, which utilizes isocratic elution and detection either by a photodiode-array detector or by two detectors set at 300 and 450 nm, have been developed to measure retinol, tocopherols and several carotenoids in human serum simultaneously. By relying on characteristic UV-visible spectra, seventeen carotenoids, retinol and alpha- and gamma-tocopherols were identified in concentrated serum extracts by use of the three-dimensional data mode of a photodiode-array detector. The presence of some recently reported carotenoids in human serum has been confirmed.

  17. A quantitative gas-liquid chromatographic method for the estimation of hecogenin and tigogenin in the leaves, juice and sapogenin concentrates of Agave sisalana.

    PubMed

    Cripps, A L; Blunden, G

    1978-05-01

    A gas-liquid chromatographic method has been devised for the routine estimation of the hecogenin [3beta-hydroxy-(25R)-5beta-spirostan-12-one] and tigogenin [ (25R)-5beta-spirostan-3beta-ol] contents of Agave sisalana leaf and juice samples and of the crude sapogenin concentrates known as "coffee grounds". Because of partial degradation of the sapogenins in the GLC system it was found necessary to acetylate the compounds prior to their estimation. In East African samples the tigogenin proportion of the total sapogenin content is usually about 10%. At this level, the 95% inverse tolerance limits on predicted tigogenin weights are approximately +/- 7%.

  18. Preparation of a novel hydrophobic affinity cryogel for adsorption of lipase and its utilization as a chromatographic adsorbent for fast protein liquid chromatography.

    PubMed

    Ünlüer, Özlem Biçen; Özcan, Ayça; Uzun, Lokman

    2014-01-01

    In this study, we have prepared a hydrophobic cryogel for the chromatographic separation of lipase from its aqueous solutions including single protein and protein mixture and also Yarrowia lipolytica cell extract. N-methacryloyl-(l)-phenylalanine methyl ester was used as a monomer to provide the hydrophobic character to the prepared cryogels. The highest adsorption capacity was observed at pH 5.0 at 0.5 mL min(-1) flow rate. The chromatographic separation of lipase was achieved from a binary mixture of lipase:bovine serum albumin (BSA) and lipase:lysozyme, and was also achieved from triple-mixture of lipase:lysozyme:BSA by using fast protein liquid chromatography. Finally, lipase purification was performed from Yarrowia lipolytica cell extract used as a natural source. These studies have shown that the hydrophobic cryogel has good chromatographic performance for the separation and purification of lipase not only from aqueous solution, but also from cell extract as a natural source of lipase. © 2013 American Institute of Chemical Engineers.

  19. Solid-phase extraction with styrene-divinylbenzene sorbent for high-performance liquid or gas chromatographic determination of urinary chloro- and methylthiotriazines.

    PubMed

    Mendas, G; Drevenkar, V; Zupancic-Kralj, L

    2001-05-25

    A solid-phase extraction (SPE) procedure on a styrene-divinylbenzene (SDB-1 cartridge) for extraction and cleaning of the triazine herbicides atrazine, simazine, ametryn, and prometryn and atrazine monodealkylated metabolites from urine samples was developed and optimised for final high-performance liquid chromatographic (HPLC-UV diode array detection) and gas chromatographic (GC-electron-capture detection and GC-thermionic-sensitive detection) analyses. Interfering polar matrices were eliminated by rinsing SDB-1 with 1% acetonitrile in water or with pure water. Extraction recoveries were from 78 to 101% with an RSD of about 10% for all studied compounds. The extraction recovery for the didealkylated atrazine metabolite was significantly lower and this compound cannot be determined with these procedures. Sorbent matrix generated interferences, although not detected by the chromatographic system, lowered the response of nitrogen-phosphorus and electron-capture GC detectors for monodealkylated chlorotriazines when compared to standards prepared in n-hexane. HPLC and GC analysis with SPE (SDB-1) preconcentration showed excellent linearity over the concentration range tested, with detection limits in urine of 10 ng ml(-1) for the parent herbicides (HPLC and GC analysis) and 20 ng ml(-1) for monodealkylated chlorotriazines (HPLC analysis).

  20. 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.

  1. 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.

  2. 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.

  3. [High performance liquid chromatography of peptide bioregulators, their fragments and derivatives. IV. Chromatographic behavior and purification of oxytocin].

    PubMed

    Grigor'eva, V D; Shatts, V D

    1989-09-01

    Chromatographic behaviour of oxytocin has been studied. A simple and convenient technique has been developed for preparative purification of oxytocin using silica and ethanol. The product obtained contains not more than 3% impurities and has activity about 450 IU/mg.

  4. Structural origin of fractional Stokes-Einstein relation in glass-forming liquids

    PubMed Central

    Pan, Shaopeng; Wu, Z. W.; Wang, W. H.; Li, M. Z.; Xu, Limei

    2017-01-01

    In many glass-forming liquids, fractional Stokes-Einstein relation (SER) is observed above the glass transition temperature. However, the origin of such phenomenon remains elusive. Using molecular dynamics simulations, we investigate the break- down of SER and the onset of fractional SER in a model of metallic glass-forming liquid. We find that SER breaks down when the size of the largest cluster consisting of trapped atoms starts to increase sharply at which the largest cluster spans half of the simulations box along one direction, and the fractional SER starts to follows when the largest cluster percolates the entire system and forms 3-dimentional network structures. Further analysis based on the percolation theory also confirms that percolation occurs at the onset of the fractional SER. Our results directly link the breakdown of the SER with structure inhomogeneity and onset of the fraction SER with percolation of largest clusters, thus provide a possible picture for the break- down of SER and onset of fractional SER in glass-forming liquids, which is is important for the understanding of the dynamic properties in glass-forming liquids. PMID:28059111

  5. Structural origin of fractional Stokes-Einstein relation in glass-forming liquids

    NASA Astrophysics Data System (ADS)

    Pan, Shaopeng; Wu, Z. W.; Wang, W. H.; Li, M. Z.; Xu, Limei

    2017-01-01

    In many glass-forming liquids, fractional Stokes-Einstein relation (SER) is observed above the glass transition temperature. However, the origin of such phenomenon remains elusive. Using molecular dynamics simulations, we investigate the break- down of SER and the onset of fractional SER in a model of metallic glass-forming liquid. We find that SER breaks down when the size of the largest cluster consisting of trapped atoms starts to increase sharply at which the largest cluster spans half of the simulations box along one direction, and the fractional SER starts to follows when the largest cluster percolates the entire system and forms 3-dimentional network structures. Further analysis based on the percolation theory also confirms that percolation occurs at the onset of the fractional SER. Our results directly link the breakdown of the SER with structure inhomogeneity and onset of the fraction SER with percolation of largest clusters, thus provide a possible picture for the break- down of SER and onset of fractional SER in glass-forming liquids, which is is important for the understanding of the dynamic properties in glass-forming liquids.

  6. 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

  7. 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.

  8. 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.

  9. Development and characterization of immobilized human organic anion transporter-based liquid chromatographic stationary phase: hOAT1 and hOAT2.

    PubMed

    Kimura, T; Perry, J; Anzai, N; Pritchard, J B; Moaddel, R

    2007-11-15

    This paper reports the development of liquid chromatographic columns containing immobilized organic anion transporters (hOAT1 and hOAT2). Cellular membrane fragments from MDCK cells expressing hOAT1 and S2 cells expressing hOAT2 were immobilized on the surface of the immobilized artificial membrane (IAM) liquid chromatographic stationary phase. The resulting stationary phases were characterized by frontal affinity chromatography, using the marker ligand [3H]-adefovir for the hOAT1 and [14C]-p-aminohippurate for the hOAT2 in the presence of multiple displacers. The determined binding affinities (Kd) for eight OAT1 ligands and eight OAT2 ligands were correlated with literature values and a statistically significant correlation was obtained for both the hOAT1 and hOAT2 columns: r2=0.688 (p<0.05) and r2=0.9967 (p<0.0001), respectively. The results indicate that the OAT1 and OAT2 have been successfully immobilized with retention of their binding activity. The use of these columns to identify ligands to the respective transporters will be presented.

  10. Development of high-performance liquid chromatographic determination of salicylaldehyde isonicotinoyl hydrazone in rabbit plasma and application of this method to an in vivo study.

    PubMed

    Kovaríková, Petra; Klimes, Jirí; Stĕrba, Martin; Popelová, Olga; Mokrý, Milan; Gersl, Vladimír; Ponka, Premysl

    2005-08-01

    An analytical methodology appropriate for the determination of the novel drug candidate salicylaldehyde isonicotinoyl hydrazone (SIH) in rabbit plasma has been developed and validated. Desirable chromatographic separation was achieved on a C18 column employing a mixture of phosphate buffer (0.01 M NaH2PO4 x 2 H2O with 2 mM EDTA, pH 6.0) and methanol (53:47; v/v) as the mobile phase. In order to develop a suitable sample preparation procedure, different methods have been tested (solid-phase extraction, liquid-liquid extraction, and protein precipitation). Protein precipitation using 0.1 M HClO4 and acetonitrile allowed the highest recoveries of the analyte to be reproducibly attained. The analytical methodology developed in this study was validated with respect to linearity (0.26-30.0 microg/mL), accuracy, precision, selectivity, recovery, and stability. A concentration of 0.26 microg/mL was determined as the LLOQ. The chromatographic method was applied to a preliminary plasma pharmacokinetic study. This study has provided the first information about the concentrations of SIH in plasma of a living subject. These results could have a significant impact on further progress in the development of this promising compound.

  11. 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.

  12. The surface tells it all: relationship between volume and surface fraction of liquid dispersions.

    PubMed

    Forel, Emilie; Rio, Emmanuelle; Schneider, Maxime; Beguin, Sebastien; Weaire, Denis; Hutzler, Stefan; Drenckhan, Wiebke

    2016-09-28

    The properties of liquid dispersions, such as foams or emulsions, depend strongly on the volume fraction ϕ of the continuous phase. Concentrating on the example of foams, we show experimentally and theoretically that ϕ may be related to the fraction ϕs of the surface at a wall which is wetted by the continuous phase - given an expression for the interfacial energy or osmotic pressure of the bulk system. Since the surface fraction ϕs can be readily determined from optical measurement and since there are good general approximations available for interfacial energy and osmotic pressure we thus arrive at an advantageous method of estimating ϕ. The same relationship between ϕ and ϕs is also expected to provide a good approximation of the fraction of the bubble or drop surface which is wetted by the continuous phase. This is a parameter of great importance for the rheology and ageing of liquid dispersions.

  13. 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.

  14. 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.

  15. Optically Imaged Striped Domains of Nonequilibrium Electronic and Nuclear Spins in a Fractional Quantum Hall Liquid

    NASA Astrophysics Data System (ADS)

    Moore, John N.; Hayakawa, Junichiro; Mano, Takaaki; Noda, Takeshi; Yusa, Go

    2017-02-01

    Using photoluminescence microscopy enhanced by magnetic resonance, we visualize in real space both electron and nuclear polarization occurring in nonequilibrium fraction quantum Hall (FQH) liquids. We observe stripelike domain regions comprising FQH excited states which discretely form when the FQH liquid is excited by a source-drain current. These regions are deformable and give rise to bidirectionally polarized nuclear spins as spin-resolved electrons flow across their boundaries.

  16. Optically Imaged Striped Domains of Nonequilibrium Electronic and Nuclear Spins in a Fractional Quantum Hall Liquid.

    PubMed

    Moore, John N; Hayakawa, Junichiro; Mano, Takaaki; Noda, Takeshi; Yusa, Go

    2017-02-17

    Using photoluminescence microscopy enhanced by magnetic resonance, we visualize in real space both electron and nuclear polarization occurring in nonequilibrium fraction quantum Hall (FQH) liquids. We observe stripelike domain regions comprising FQH excited states which discretely form when the FQH liquid is excited by a source-drain current. These regions are deformable and give rise to bidirectionally polarized nuclear spins as spin-resolved electrons flow across their boundaries.

  17. 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.

  18. Fractionalized excitations in the spin-liquid state of a kagome-lattice antiferromagnet.

    PubMed

    Han, Tian-Heng; Helton, Joel S; Chu, Shaoyan; Nocera, Daniel G; Rodriguez-Rivera, Jose A; Broholm, Collin; Lee, Young S

    2012-12-20

    The experimental realization of quantum spin liquids is a long-sought goal in physics, as they represent new states of matter. Quantum spin liquids cannot be described by the broken symmetries associated with conventional ground states. In fact, the interacting magnetic moments in these systems do not order, but are highly entangled with one another over long ranges. Spin liquids have a prominent role in theories describing high-transition-temperature superconductors, and the topological properties of these states may have applications in quantum information. A key feature of spin liquids is that they support exotic spin excitations carrying fractional quantum numbers. However, detailed measurements of these 'fractionalized excitations' have been lacking. Here we report neutron scattering measurements on single-crystal samples of the spin-1/2 kagome-lattice antiferromagnet ZnCu(3)(OD)(6)Cl(2) (also called herbertsmithite), which provide striking evidence for this characteristic feature of spin liquids. At low temperatures, we find that the spin excitations form a continuum, in contrast to the conventional spin waves expected in ordered antiferromagnets. The observation of such a continuum is noteworthy because, so far, this signature of fractional spin excitations has been observed only in one-dimensional systems. The results also serve as a hallmark of the quantum spin-liquid state in herbertsmithite.

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

    PubMed

    Harp, Bhakti Petigara; Barrows, Julie N

    2009-01-01

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

  20. Void fraction in two-phase flow in liquid impingement cooling system

    SciTech Connect

    Ohsone, Yasuo; Nakajima, Tadakatsu; Sasaki, Shigeyuki; Nishihara, Atsuo; Hirasawa, Shigeki

    1995-12-31

    Void fractions in forced-convection subcooled boiling were analyzed to gain information for designing a liquid impingement cooling system for electronic devices. The boiling vessel used in this study has a 160 mm x 160 mm heater. The heater is positioned to face jets of dielectric fluorocarbon (C{sub 6}F{sub 14},FC-72) liquid from circular nozzles 4 mm in diameter. The distance between the heater surface and the nozzles is 6 mm. The test section, which can be rotated 360 degrees, consists of 1.03-m-long acrylic pipes, 20 mm and 15 mm in diameter allows experiments to be conducted for both horizontal and vertical flow. Void fractions in the test section were examined with respect to variations in liquid jet temperature (T{sub Lin} = 26 C and 36C); nozzle exit velocity (U = 0.37--10 m/s); liquid pressure in the vessel (P{sub m} = 115--118 kPa); and heat flux in the heater (q = 3--50 W/cm{sup 2}). Results show that the effects on void fractions during liquid jet impingement flow boiling of nozzle exit velocity, pressure in the vessel, and heat flux in the heater, can be estimated by revising the exponents of these variables depending on the pressure of Miropolskii`s correlation of channel flow boiling.

  1. Bound states of fractionalized excitations in a modulated Kitaev spin liquid

    NASA Astrophysics Data System (ADS)

    Théveniaut, Hugo; Vojta, Matthias

    2017-08-01

    Fractionalization is a hallmark of spin-liquid behavior; it typically leads to response functions consisting of continua instead of sharp modes. However, microscopic processes can enable the formation of short-distance bound states of fractionalized excitations, despite asymptotic deconfinement. Here we study such bound-state formation for the Z2 spin liquid realized in Kitaev's honeycomb compass model, supplemented by a kekulé distortion of the lattice. Bound states between flux pairs and Majorana fermions form in the Majorana band gaps. We calculate the dynamic spin susceptibility and show that bound states lead to sharp modes in the magnetic response of the spin liquid, with the momentum dependence of the corresponding spectral weight encoding the internal symmetry of the bound state. As a byproduct, we also show that isolated fluxes may produce Majorana bound states at exactly zero energy. Generalizations and implications of the results are discussed.

  2. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. A reversed-phase high-performance liquid chromatographic method for the determination of zafirlukast in pharmaceutical formulations and human plasma.

    PubMed

    Süslü, Incilay; Altinöz, Sacide

    2006-01-01

    Zafirlukast (ZAF) is a leukotriene receptor antagonist used in the treatment of chronic asthma. In this study, a simple and sensitive reversed-phase, high-performance liquid chromatographic method was developed for the determination of ZAF in pharmaceutical formulations and human plasma. Piribedil was used as an internal standard. Analysis was carried out on a Nucleosil C18 100 A (150 mm x 4.6 mm id, 5 Vm) column with acetonitrile-pH 3.0 acetate buffer (70 + 30, v/v) as the mobile phase at a flow rate of 0.8 mL/min. The peak was detected by an ultraviolet detector set at a wavelength of 240 nm. The retention times were about 3.9 min for piribedil and 5.8 min for ZAF. The developed method was applied to the determination of ZAF in its pharmaceutical formulation and spiked human plasma. For quantification of ZAF in spiked plasma, proteins were precipitated with ethanol before chromatographic analysis. The calibration range was linear from 49.69-437.50 ng/mL in spiked plasma. The absolute recovery from spiked plasma was 98.73 +/- 0.42% at a concentration of 254.78 ng/mL of ZAF. No endogenous substances from plasma were found to interfere.

  4. 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.

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

    PubMed

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

    2013-01-01

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

  6. High-performance liquid chromatographic determination of 17beta-estradiol and 17beta-estradiol-3-acetate solubilities and diffusion coefficents in silicone elastromeric intravaginal rings.

    PubMed

    Russell, J A; Malcolm, R K; Campbell, K; Woolfson, A D

    2000-07-07

    A rapid, sensitive reversed-phase high-performance liquid chromatographic method has been developed for the determination of in vitro release of 17beta-estradiol and its ester prodrug, 17beta-estradiol-3-acetate, from silicone intravaginal rings. Partial hydrolysis of the acetate under the aqueous conditions provided by the 1% benzalkonium chloride release medium necessitates its conversion to 17beta-estradiol prior to HPLC analysis. Both steroid peaks have been fully resolved from the benzalkonium chloride peaks by the reported chromatographic method, which employs a C18 bonded reversed-phase column, an acetonitrile-water (50:50, v/v) mobile phase and a UV detection wavelength of 281 nm. The peak area versus 17beta-estradiol concentration was found to be linear over the range of 0.0137-1347 microkg ml(-1). The HPLC method has also been used to determine the silicone solubilities and diffusion coefficients of the two related steroids. The almost 100-fold increase in 17beta-estradiol-3-acetate release from the silicone core-type intravaginal rings compared to 17beta-estradiol is shown to be due to a 60-fold increase in silicone solubility and a one and a half-fold increase in diffusitivity. The results demonstrate that an effective estrogen replacement therapy dose of 17beta-estradiol may be administered from a silicone intravaginal reservoir device containing the labile 17beta-estradiol-3-acetate prodrug.

  7. Simultaneous estimation of amlodipine besylate and nebivolol hydrochloride in tablet dosage forms by reverse phase-high-performance liquid chromatographic using ultraviolet detection

    PubMed Central

    Sharma, Deepak; Jain, Anurekha; Shrivastava, Alankar

    2011-01-01

    Background: The present study aimed to develop and validate the simultaneous estimation of amlodipine and nebivolol in tablet dosage forms. Materials and Methods: An isocratic reversed phase high-performance liquid chromatographic (HPLC) method with ultraviolet detection at 268 nm has been developed for the determination of amlodipine besylate (ADB) and nebivolol hydrochloride in dosage formulation. Results: Good chromatographic separation was achieved by using a stainless steel analytical column, the Lichrospher ODS RP-18 column (250 × 4 mm), particle size 5 μm. The system was operated at ambient temperature (25 ± 2°C) using a mobile phase consisting of acetonitrile (ACN) and a phosphate buffer (pH 3.0), mixed in a ratio of 40 : 60 at a flow rate of 0.8 ml/minute. The slope, intercept, and correlation coefficient were found to be 8818.2, - 18159, and 0.9993 for amlodipine and 9048.7, 108595, and 0.9998 for nebivolol, respectively. The proposed method was validated for its specificity, linearity, accuracy, and precision. Conclusion: The method was found to be suitable for the quality control of amlodipine besylate and nebivolol hydrochloride simultaneously in a bulk drug as well as in a formulation. PMID:23781423

  8. 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

  9. Liquid chromatographic analysis of the cis(Z)- and trans(E)-isomers of clopenthixol in human plasma using a novel solid phase extraction procedure.

    PubMed

    Pucci, Vincenzo; Bugamelli, Francesca; Mandrioli, Roberto; Bartoletti, Claudio; Rossi, Nicola; Raggi, Maria Augusta

    2003-07-25

    A simple and highly sensitive high-performance liquid chromatographic (HPLC) method for the simultaneous determination of cis(Z)-clopenthixol and trans(E)-clopenthixol in human plasma has been developed. The chromatographic analysis was carried out isocratically on a reversed-phase column (C(8) 150 x 4.6 mm I.D., 5 microm) using a mixture of 25 mM phosphate buffer and acetonitrile (65:35 v/v, pH* 3.0) as the mobile phase, and ultraviolet detection at 230 nm. Plasma sample pretreatment was accomplished by means of an original solid-phase extraction (SPE) procedure carried out on cyanopropyl cartridges, with a high extraction yield and good selectivity. Under the optimum conditions, calibration graphs of spiked human plasma samples were obtained over the concentration ranges 1-300 ng ml(-1) for cis(Z)-clopenthixol and 1-200 ng ml(-1) for trans(E)-clopenthixol. The limit of detection (LOD) was 0.3 ng ml(-1) for both cis(Z)- and trans(E)-isomers of clopenthixol. The method was successfully applied to the determination of cis(Z)-clopenthixol and trans(E)-clopenthixol in plasma samples of schizophrenic patients undergoing therapy with zuclopenthixol.

  10. 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. Copyright © 2015 John Wiley & Sons, Ltd.

  11. High-performance liquid chromatographic determination of polyamines in milk as their 9-fluorenylmethoxycarbonyl derivatives using a column-switching technique.

    PubMed

    Bellagamba, F; Moretti, V M; Mentasti, T; Albertini, A; Luzzana, U; Valfrè, F

    1997-12-12

    A high-performance liquid chromatographic method for the determination of polyamines in milk is milk is described. Polyamines were extracted in perchloric acid and derivatized with 9-fluorenylmethoxycarbonyl chloride (FMOC-Cl). The excess of reagent was reacted with aspartic acid before the analysis on a column-switching system. Linearity of derivatization was calculated for each amine and the coefficient of regression ranged from 0.994 to 0.999. Chromatographic separation of FMOC-polyamines was achieved with a gradient elution programme of water-acetonitrile. The correlation coefficients of the standard curves in the concentration range from 0.5 to 5 nmol ml-1 were higher than 0.991. The repeatability of the method, expressed as R.S.D. for each polyamines ranged from 3.0 to 8.6%. The percent mean recoveries at 1 nmol ml-1 spiking level were 49 +/- 3, 58 +/- 5, 61 +/- 5 and 48 +/- 4 for putrescine, cadaverine, spermidine and spermine, respectively. The limit of detection, calculated on the basis of three times signal-to-noise ratio, was 50 pmol ml-1 for each polyamine.

  12. The Development and Validation of Novel, Simple High-Performance Liquid Chromatographic Method with Refractive Index Detector for Quantification of Memantine Hydrochloride in Dissolution Samples.

    PubMed

    Sawant, Tukaram B; Wakchaure, Vikas S; Rakibe, Udyakumar K; Musmade, Prashant B; Chaudhari, Bhata R; Mane, Dhananjay V

    2017-07-01

    The present study was aimed to develop an analytical method for quantification of memantine (MEM) hydrochloride in dissolution samples using high-performance liquid chromatography with refractive index (RI) detector. The chromatographic separation was achieved on C18 (250 × 4.5 mm, 5 μm) column using isocratic mobile phase comprises of buffer (pH 5.2):methanol (40:60 v/v) pumped at a flow rate of 1.0 mL/min. The column effluents were monitored using RI detector. The retention time of MEM was found to be ~6.5 ± 0.3 min. The developed chromatographic method was validated and found to be linear over the concentration range of 5.0-45.0 μg/mL for MEM. Mean recovery of MEM was found to be 99.2 ± 0.5% (w/w). The method was found to be simple, fast, precise and accurate, which can be utilized for the quantification of MEM in dissolution samples. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  13. 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.

  14. Quantitative analysis and chromatographic fingerprinting of the semen zizyphi spinosae by ultra-high-performance liquid chromatography coupled with diode-array detector.

    PubMed

    Niu, Chunyan; Zhang, Jinlan

    2011-11-01

    A simple and sensitive method was developed and validated for fingerprint analysis of semen zizyphi spinosae (SZS) and simultaneous determination of six flavonoids in SZS by ultra-high-performance liquid chromatography coupled to diode-array detector (DAD). The analysis was performed on an Agilent ZORBAX Eclipse Plus C18 RRHD column. The column was maintained at 40°C and the eluents were monitored with DAD at 270 nm. A gradient elution of acetonitrile and water containing 20 mM sodium dihydrogen phosphate was used. The solvent flow rate was 0.4 mL/min. The method was validated. Standard calibration curves showed good linear behaviors (r=1.000) in the range of 0.33-201.00 μg/mL. Acceptable intra-day precision (RSD<1.9%), inter-day precision (RSD<4.0%), repeatability (RSD<4.1%) and recovery in the range of 97.4-104% were obtained. The validated method was successfully applied to obtain the chromatographic fingerprints and the contents of six flavonoids in 23 samples of SZS. The principal component analysis (PCA) had been applied for the chromatographic fingerprint analysis and quantitative analysis of six flavonoids to classify and discriminate the 23 samples of SZS. These results demonstrated that the method was very suitable in the analysis and quality control of SZS. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. 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.

  16. Optimization of liquid chromatographic method for the separation of nine hydrophilic and hydrophobic components in Salviae miltiorrhizae Radix et Rhizoma (Danshen) using microemulsion as eluent.

    PubMed

    Huang, Hongzhang; Xuan, Xueyi; Xu, Liyuan; Yang, Jianrui; Gao, Chongkai; Li, Ning

    2014-04-01

    In this study, we have proposed and developed a novel, environmental-friendly and simple method for separation of nine hydrophilic and hydrophobic components in Danshen using microemulsion liquid chromatography. The proposed method was optimized via the preliminary screening experiment and the experimental design. The following factors were investigated in preliminary screening experiment: pH of mobile phase, column type, the nature of surfactant, the nature of oil phase and additives. In order to simultaneously optimize resolution and analysis time, the chromatographic optimization function (COF) was adopted to evaluate chromatograms. The central composite design (CCD) was used to create the matrix of experiments for mapping the chromatographic response surface. Finally, the COF values were fitted into a second order polynomial model and the response surface methodology (RSM) was employed to find the optimal eluent constituents. The reliability of the established model was confirmed by the good agreement obtained between experimental data and predictive values. Based on the results from the preliminary screening experiment and the CCD optimization, the optimal mobile phase was identified as a solution consisting of 6.68% (w/w) polyoxyethylene lauryl ether (Brij35), 0.84% (w/w) cyclohexane, 6.92% (w/w) n-butanol, 85.56% (w/w) phosphate buffer (pH 6.60) and 8mM cetyltrimethyl ammonium bromide (CTAB).

  17. 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.

  18. Protein-bound carbohydrates in breast cancer. Liquid-chromatographic analysis for mannose, galactose, fucose, and sialic acid in serum.

    PubMed

    Mrochek, J E; Dinsmore, S R; Tormey, D C; Waalkes, T P

    1976-09-01

    We describr high-resolution chromatographic analysis for protein-bound sialic acid in serum, with use of a cerate oxidimetric detector. Values for sera from normal women averaged 680.5 mg/liter, with a coefficient of variation of 23%. Including data obtained by previously developed chromatographic procedures for protein-bound mannose, galactose, and fucsoe, we assessed sera from breast-cancer patients whose malignancy had been categorized as either stable, responsive, or progressive (based on clinical observations spaced from two to five months apart). All of 12 responsive patients had decreases of protein-bound fucose averaging 34.5% (SD, 16.1) and all of 10 patients with progressive disease had increases averaging 38.3% (SD 21.5). Changes in fucose averaged less than 6.7% (SD, 4.9) for eight patients with clinically stable breast cancer. Changes in protein-bound mannose, galactose, and sialic acid did not correlate as well as did fucose with the clinical disease status of the patients.

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

    PubMed

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

    2014-12-29

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

  20. 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.

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

    SciTech Connect

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

    1981-07-01

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

  2. Column reversed-phase high-performance liquid chromatographic method for simultaneous determination of rabeprazole sodium and domperidone in combined tablet dosage form.

    PubMed

    Sabnis, Shweta Sadanand; Dnvandev, Dhavale Nilesh; Jadhav, Vijay Yeshawantrao; Gandhi, Santosh Vilashchand

    2008-01-01

    A new, simple column reversed-phase high-performance liquid chromatographic (HPLC) method for simultaneous determination of rabeprazole sodium (RAB) and domperidone (DOM) in a combined tablet dosage form has been developed and validated. Determination was performed using a Jasco HPLC system with a HiQ SiL octadecylsilane (C18) column (250 x 4.6 mm id), acetonitrile-0.1 M ammonium acetate (50 + 50, v/v) mobile phase, and paracetamol as an internal standard. The detection was performed using a UV detector set at 280 nm. The method was validated with respect to linearity, accuracy, precision, and robustness. Beer's law was obeyed in the concentration range of 1.0-10.0 and 0.5-5.0 microg/mL for RAB and DOM, respectively. The method has been successfully applied for the analysis of drugs in a pharmaceutical formulation.

  3. Liquid chromatographic determination of serum levels of d,l-4-amino-N-(alpha-methylbenzyl)-benzamide, a new benzamide anticonvulsant.

    PubMed

    Dockens, R C; Ravis, W R; Clark, C R

    1988-01-01

    A method for the high-performance liquid chromatographic (HPLC) determination of serum concentrations of d,l-4-amino-N-(alpha-methylbenzyl)-benzamide and its N-acetylated metabolite is described. The compounds are isolated from a 50-microL sample of serum using solid phase extraction. The compounds and internal standard are eluted from the extraction column with acetonitrile. Quantitation is performed via UV detection at 275 nm following isocratic reversed-phase (C18) separation using a ternary solvent system. The assay procedure is useful for the determination of concentrations of parent compound from 0.63 to 87.9 micrograms/mL from 50 microL of serum.

  4. High-performance liquid chromatographic method for the determination of the dinitrocarbanilide component of nicarbazin in eggs with on-line clean-up.

    PubMed

    Tarbin, J A; Shearer, G

    1993-04-02

    A high-performance liquid chromatographic method for the determination of the dinitrocarbanilide component of the anti-coccidial drug nicarbazin has been developed. The drug was extracted from egg with acetonitrile. The extract was evaporated to dryness and taken up in water-acetonitrile (80:20, v/v). The extract was then injected onto a reversed-phase precolumn. After clean-up with 20% aqueous acetonitrile for 5 min, the precolumn was eluted onto a Chromspher C18 cartridge column with 0.01 M potassium dihydrogen-phosphate pH 4.0-acetonitrile (50:50, v/v). Detection was by ultraviolet at 343 nm. Average recoveries at five levels from 0.005 to 0.500 mg kg-1 were > 80%. The limit of determination was 0.005 mg kg-1.

  5. On-line continuous sampling dynamic microwave-assisted extraction coupled with high performance liquid chromatographic separation for the determination of lignans in Wuweizi and naphthoquinones in Zicao.

    PubMed

    Gao, Shiqian; You, Jingyan; Wang, Ying; Zhang, Rui; Zhang, Hanqi

    2012-03-01

    The on-line continuous sampling dynamic microwave-assisted extraction (on-line CSDMAE) coupled with high-performance liquid chromatographic separation and determination of the lignans in Wuweizi and naphthoquinones in Zicao was developed. The extraction, separation and determination of target analytes were simultaneously carried out. The experimental parameters, including type of extraction solvent, microwave extraction power, solvent flow rate, amount of sample and particle size of the sample, were evaluated by the univariate method and orthogonal screening. The detection limits for schisandrin A, schisantherin A, deoxyschizandrin, shikonin and β,β'-dimethylacrylshikonin are 0.86, 0.90, 0.27, 0.42 and 0.92 μg mL⁻¹, respectively. Compared with the conventional extraction methods, such as off-line continuous microwave-assisted extraction, ultrasound-assisted extraction and Soxhlet extraction, the proposed method is quicker and more effective.

  6. Particle size analyses of porous silica and hybrid silica chromatographic support particles. Comparison of flow/hyperlayer field-flow fractionation with scanning electron microscopy, electrical sensing zone, and static light scattering.

    PubMed

    Xu, Yuehong

    2008-05-16

    Porous silica and hybrid silica chromatographic support particles having particle diameters ranging approximately from 1 microm to 15 microm have been characterized by flow/hyperlayer field-flow fractionation (FFF). The particle size accuracy has been improved significantly in this work by a second-order polynomial calibration. Very good agreement between the FFF data and scanning electron microscopic (SEM) results has been achieved. The effects of particle porosity, pore sizes, and particle sizes on the particle size accuracy in electrical sensing zone (ESZ) analyses have been discussed. It has been demonstrated by computer simulation and experimental measurements that false peaks can be generated in certain particle size regions when the static light scattering (SLS) technique is applied to tightly distributed spherical chromatographic support particles.

  7. Liquid chromatographic-mass spectrometry analysis and pharmacokinetic studies of a novel rabeprazole formulation, sterile powder for injection, in dogs and rats.

    PubMed

    Shao, Feng; Sun, Jianguo; Wang, Guangji; Xie, Haitang; Zhu, Xiaoyan; Zhang, Jingwei

    2007-05-01

    Rabeprazole is among the most potent proton pump inhibitors (PPI) identified to date and it has been demonstrated that it is effective in such diseases as gastroesophageal reflux disease (GERD), duodenal ulcer and gastric ulcer. There is currently interest in developing a new formulation: rabeprazole sterile powder for injection (RSPI). This investigation was conducted to evaluate the preclinical pharmacokinetics of RSPI in rats and at the same time a comparative study was carried out in dogs between RSPI and Pariet tablets using liquid chromatographic-mass spectrometry analysis. The liquid chromatographic-mass spectrometry method was first conducted and validated as being specific, and having accuracy, precision, sensitivity and a satisfactory recovery. After intravenous administration of RSPI (i.v.: 2, 6 and 18 mg/kg) to rats, no significant dose-dependency was found in the CL (4.20-5.72 l/h/kg), V(area) (d) (0.94-1.32 l/kg), dose-normalized AUC (197.20-245.82 microg/l*h based on 1 mg/kg) and t(1/2) (p>0.05). In the dog, a randomized, open-label, crossover experiment was carried out to show that the mean area under the plasma concentration-time curve (AUC(0-infinity)) after i.v. administration of RSPI was at least four times larger than that following oral administration of Pariet tablet at an equivalent dose but the elimination half-life of these two formulation was similar (p>0.05). The results showed that the pharmacokinetics of RSPI was linear (r(2) = 0.98) in the dose range 2-18 mg/kg and the RSPI had a much higher AUC(0-infinity) and similar t(1/2) values compared with the enteric-coated tablet. Copyright (c) 2007 John Wiley & Sons, Ltd.

  8. 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

  9. High-performance liquid chromatographic method for the simultaneous determination of nalbuphine and its prodrug, sebacoyl dinalbuphine ester, in dog plasma and application to pharmacokinetic studies in dogs.

    PubMed

    Pao, L H; Hsiong, C H; Hu, O Y; Ho, S T

    2000-09-15

    For the determination of nalbuphine and its long acting prodrug, sebacoyl dinalbuphine ester (SDN), in biological samples, a reversed-phase high-performance liquid chromatographic method using dual detectors was established. Ultraviolet and fluorescence detectors were connected in series for determining SDN and nalbuphine, respectively. The two analytes and internal standard were extracted from plasma by alkaline liquid-liquid extraction using n-hexane-isoamyl alcohol (9:1, v/v). The calibration curve for nalbuphine was linear over the range from 10 to 2,500 ng/ml, while the range was 25 to 2,500 ng/ml for SDN. The within- and between-day precision and accuracy were all within 10% for both nalbuphine and SDN over these concentrations. The method was applied successfully to a pharmacokinetic study of SDN administered at 20 mg/kg to two beagle dogs. Pharmacokinetic analysis revealed that SDN followed a linear one-compartment model with an elimination half-life of 74.7 min. Formation of nalbuphine after intravenous administration of SDN was observed in the first time point sample (5 min). These results indicate that SDN is rapidly metabolized to its active moiety, nalbuphine, in dogs and no other metabolites are detected in plasma.

  10. Fraction transfer process in on-line comprehensive two-dimensional liquid-phase separations.

    PubMed

    Česla, Petr; Křenková, Jana

    2017-01-01

    Two-dimensional liquid-phase separations have gained increasing attention for their ability to separate complex sample mixtures. Among the experimental setups used, an on-line approach is preferred to reduce the probability of sample contamination, for easier automation and high-sample throughput. The interfacing of the separation techniques in the on-line mode brings additional demands on proper optimization of the two-dimensional system. In this review, the possibilities of the on-line coupling of liquid chromatography and liquid chromatography with capillary electrophoresis in two-dimensional systems are discussed. Special attention is paid to the fraction transfer process, which includes an overview of interfaces and experimental setups applied, the compatibility issues of separation systems, and instrumental parameters. The benefits and drawbacks of using electromigration separations in combination with liquid chromatography are presented as well.

  11. 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.

  12. 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.

  13. An approach to develop binary chromatographic fingerprints of the total alkaloids from Caulophyllum robustum by high performance liquid chromatography/diode array detector and gas chromatography/mass spectrometry.

    PubMed

    Li, Yiping; Hu, Zhen; He, Langchong

    2007-04-11

    An approach was proposed to develop binary chromatographic fingerprints by means of high performance liquid chromatography/diode array detector (HPLC/DAD) and gas chromatography/mass spectrometry (GC/MS). HPLC fingerprint and GC/MS fingerprint that, respectively, represent chemical characteristics of aporphinoid and quinolizidine alkaloids of the total alkaloids from Caulophyllum robustum were developed, which were used to construct binary chromatographic fingerprints of the total alkaloids. Moreover, the authentication and validation of the binary fingerprints were performed. Then, a data-level information fusion method was employed to capture the chemical information encoded in two chromatographic fingerprints. Finally, based on the fusion results, the quality of 10 batches of the total alkaloids samples was further evaluated by similarity measure and cluster analysis method. In comparison with conventional fingerprint, the binary chromatographic fingerprints which represent the characteristics of more constitutions can comprehensively and properly reveal the quality characteristics of the total alkaloids. The binary chromatographic fingerprints can reach more objective conclusions in the practice of quality control of the total alkaloids. In conclusion, the binary chromatographic fingerprints are suitable for quality control of the total alkaloids. The presented approach is a powerful and meaningful tool to comprehensively conduct the quality control of traditional Chinese medicine (TCM).

  14. Acoustic Monitor for Liquid-Solid Slurries Measurements at Low Weight Fractions

    SciTech Connect

    Tavlarides, L. L.; Sangani, A.; Shcherbakov, A.; Lee, J. S.; Dievendorf, E.

    2003-06-15

    The principal objective of the project is to develop an acoustic probe for determining the weight fraction of particles in a flowing suspension. The suspension can be solid-liquid (S-L) or solid-gas-liquid (S-G-L). The work will include testing the theory of acoustic wave propagation in suspensions and demonstrating the application of the probe by installing it on a flow loop through which a suspension is flowing and determining the particle weight fraction. The signal from the probe must be processed such that the noise arising from the presence of gas bubbles is removed to yield an accurate estimate of the particle weight fraction. Particular attention will be given to testing suspensions with low particle weight fractions since slurries to be transported in nuclear waste processing will have low particle weight fractions. Originally, the probe was to be developed and tested at Syracuse University (SU) then installed and tested at Oak Ridge National Laboratories (ORNL) for surrogate slurries from the Hanford Nuclear site. However, after discussions between SU and ORNL in June 2002 it was agreed that all tests would be conducted at SU.

  15. Acoustic Monitor for Liquid-Solid Slurries Measurements at Low Weight Fractions

    SciTech Connect

    Tavlarides, L. L.; Sangani, A.; Shcherbakov, A.; Lee, J. S.; Dievendorf, E.

    2002-10-15

    The principal objective of the project is to develop an acoustic probe for determining the weight fraction of particles in a flowing suspension. The suspension can be solid-liquid (S-L) or solid-gas-liquid (S-G-L). The work will include testing the theory of acoustic wave propagation in suspensions and demonstrating the application of the probe by installing it on a flow loop through which a suspension is flowing and determining the particle weight fraction. The signal from the probe must be processed such that the noise arising from the presence of gas bubbles is removed to yield an accurate estimate of the particle weight fraction. Particular attention will be given to testing suspensions with low particle weight fractions since slurries to be transported in nuclear waste processing will have low particle weight fractions. Originally, the probe was to be developed and tested at Syracuse University (SU) then installed and tested at Oak Ridge National Laboratories (ORNL) for surrogate slurries from the Hanford Nuclear site. However, after discussions between SU and ORNL in June 2002 it was agreed that all tests would be conducted at SU.

  16. 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.

  17. 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.

  18. 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.

  19. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. [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.

  1. 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.

  2. Influence of the hydrothermal treatment on the chromatographic properties of monolithic silica capillaries for nano-liquid chromatography or capillary electrochromatography.

    PubMed

    Puy, G; Roux, R; Demesmay, C; Rocca, J-L; Iapichella, J; Galarneau, A; Brunel, D

    2007-08-10

    In the last decade, silica monolithic capillaries have focused more and more attention on miniaturized separation techniques like capillary electrochromatography (CEC), nano-liquid chromatography (nano-LC) and chip electrochromatography owing to their unique chromatographic properties and their simplified preparation compared with packed columns. They are synthesized according to a sol-gel multi-step process that includes, after a gelation step at 40 degrees C leading to the formation of the macropores network and the silica skeleton, a post-gelation step (hydrothermal treatment at 120 degrees C in basic medium) that allows to tailor the mesopores and finally a calcination or a washing step to remove remaining polymers. In order to reduce the synthesis time, the number of synthesis steps and above all the temperature synthesis, to adapt the synthesis of such silica monoliths in polymeric microsystem devices, we extensively studied the influence of the hydrothermal treatment and its duration on textural (pore size distribution) and chromatographic properties (retention, efficiency) of in situ-synthesized capillary monoliths in nano-LC and CEC. This study was performed on pure silica and octyl chains grafted silica monoliths. Untreated monoliths show small pores (<6 nm), whereas hydrothermally treated monoliths exhibit medium and large mesopores (8-17 nm). It was demonstrated that the hydrothermal treatment at 120 degrees C was not necessary for pure silica monolithic capillaries dedicated to normal phase liquid chromatography or hydrophilic interaction liquid chromatography (HILIC) and electrochromatography: the suppression of the hydrothermal treatment did not impair efficiencies in CEC and in nano-LC but contributed to increase in retention factors. Minimal plate heights of ca. 5 microm in CEC and 6 microm in nano-LC were obtained with or without hydrothermal treatment with bare silica. In the same way, the hydrothermal treatment was not necessary for grafted

  3. 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

    2016-02-29

    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.

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

    PubMed

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

    2007-11-01

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

  5. Development and validation of a sensitive liquid chromatographic-tandem mass spectrometric method for the determination of cromolyn sodium in human plasma.

    PubMed

    Lin, Zhongping John; Abbas, Richat; Rusch, Lorraine M; Shum, Linyee

    2003-05-05

    Cromolyn sodium is a safe compound with potent anti-allergic properties when used locally or topically. Clinical data from systemic exposure is not available because of the poor GI absorption when given orally. In order to evaluate a new approach to enhance the absorption and bioavailability of cromolyn sodium, a sensitive assay was needed to support an oral-dose study in humans. This paper describes a liquid chromatographic-tandem mass spectrometric (LC-MS-MS) method for the analysis of cromolyn sodium in human plasma. The method consists of a two-step extraction with subsequent analysis using a high-performance liquid chromatography electrospray tandem mass spectrometer system. The compounds were eluted isocratically on a C(18) column followed by a backflush. The total run time is 6 min. The standard curve of cromolyn sodium was over the range of 0.313 to 750 ng/mL with a lower limit of quantitation (LLOQ) of 0.313 ng/mL when 0.5 mL of plasma was used for analysis. The percent coefficient of variation (C.V.) for accuracy and precision (inter-assay and intra-assay) was less than 15% over the validated concentration range and the coefficients of determination, r(2), were >0.991577. The method is simple, sensitive, and selective, and has been successfully utilized for oral cromolyn sodium clinical studies.

  6. Improved high-performance liquid chromatographic analysis of some carboxylic acids in food and beverages as their p-nitrobenzyl esters.

    PubMed

    Badoud, R; Pratz, G

    1986-06-06

    An improved, straightforward and accurate method for the derivatization and quantitative high-performance liquid chromatographic analysis of carboxylic acids in food and beverages is presented. Thirty-two p-nitrobenzyl esters were prepared in high yields by direct reaction of the free acid with O-(4-nitrobenzyl)-N,N'-diisopropylisourea in dioxane-water (9:1). Benzylmalonic acid was used as a new internal standard. Excess of reagent was removed on a strong cation-exchange resin. The advantage of this original and very convenient procedure over the usual clean-up step involving filtration through a disposable silica cartridge is discussed. The p-nitrobenzyl ester derivatives were readily separated using a single linear gradient of solvent (acetonitrile in water). With a high-performance liquid chromatography column of conventional size (20-25 cm X 4.6 mm I.D.), the analysis lasted for less than 20 min. This analysis time was even shorter (less than 12 min) when using modern small-bore (100 X 2.1 mm I.D.) columns. Applications of the method to the analysis of the main carboxylic acids in coffee, wine and fruit juices are presented.

  7. 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.

  8. Development of a High-Performance Liquid Chromatographic Method for Determination of Letrozole in Wistar Rat Serum and its Application in Pharmacokinetic Studies

    PubMed Central

    Acharjya, Sasmita Kumari; Bhattamisra, Subrat Kumar; Muddana, Bhanoji Rao E.; Bera, Ravikumar V. V.; Panda, Pinakini; Panda, Bibhu Prasad; Mishra, Gitanjali

    2012-01-01

    A fast, sensitive, and specific reversed-phase high-performance liquid chromatographic (RP–HPLC) method for the determination of letrozole in Wistar rat serum was developed. In this method, liquid–liquid extraction of letrozole was achieved using diethyl ether as the extracting solvent. The analysis was carried out on a reversed-phase C18 (250 mm × 4.6 mm, 5 μm) column with an isocratic mobile phase of methanol–water (70:30,v/v), at a flow rate of 1.0 mL min−1. Detection was carried out at 239 nm with a UV–visible spectrophoto-metric detector. The method was shown to be selective and linear over the concentration range of 0.15–100 μg mL−1. The intra-day and inter-day precision studies showed good reproducibility with coefficients of variation less than 11% for the analyte. The relative errors of intra– and inter–day accuracy were within −11.52 to −2.26%. The limit of quantification was evaluated to be 0.15 μg mL−1. The method was successfully applied for the pharmacokinetic study of letrozole after oral administration of 10 mg kg−1 of letrozole in six healthy Wistar rats. PMID:23264941

  9. 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.

  10. A Robust Liquid Chromatographic Method for Confirmation of Drug Stability of Azithromycin in Bulk Samples, Tablets and Suspensions

    PubMed Central

    Okaru, Alex O.; Abuga, Kennedy O.; Kamau, Franco N.; Ndwigah, Stanley N.; Lachenmeier, Dirk W.

    2017-01-01

    A simple, isocratic and robust RP-HPLC method for the analysis of azithromycin was developed, validated and applied for the analysis of bulk samples, tablets and suspensions. The optimum chromatographic conditions for separation were established as a mobile phase comprised of acetonitrile-0.1 M KH2PO4 pH 6.5–0.1 M tetrabutyl ammonium hydroxide pH 6.5-water (25:15:1:59 v/v/v/v) delivered at a flow rate of 1.0 mL/min. The stationary phase consisted of reverse-phase XTerra® (250 mm × 4.6 mm i.d., 5 µm particle size) maintained at a temperature of 43 °C with a UV detection at 215 nm. The method was found to be linear in the range 50%–150% (r2 = 0.997). The limits of detection and quantification were found to be 0.02% (20 µg) and 0.078% (78 µg), respectively, with a 100.7% recovery of azithromycin. Degradation products of azithromycin in acidic and oxidative environments at 37 °C were resolved from the active pharmaceutical ingredient and thus the method is fit for the purpose of drug stability confirmation. PMID:28245574

  11. High-performance liquid chromatographic resolution of 1-(1,4-benzodioxane-2-formyl)-piperazine enantiomers after chiral derivatization.

    PubMed

    Chen, Zhiqiong; Yu, Yu; Li, Longjiang

    2005-02-01

    Chiral separation of racemic mixtures is of the greatest importance to the pharmaceutical industry, as the isomers of a given racemate may exhibit substantially different pharmacological effects, not to mention possibly differing toxicity behaviour. A novel chiral separation method is developed for the determination of 1-(1,4-benzodioxane-2-formyl)piperazine (BFP) enantiomers. The indirect resolution is performed by applying precolumn derivatization with the chiral reagent 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl isothiocyanate (GITC). The resulting diastereoisomers are separated on a reversed-phase ODS column with methanol-potassium dihydrogen phosphate (0.02mol/L, 50:50) as mobile phase. UV detection is at 250 nm. The effect of mobile phase composition upon resolution and analysis time is investigated. Two diastereoisomers show nearly base-line separation under optimal chromatographic conditions. The presented study provides a simple and accurate method for the enantiomeric quality control and the optical purity assay of BFP.

  12. 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.

  13. Validation and application of high performance liquid chromatographic method for the estimation of metoclopramide hydrochloride in plasma.

    PubMed

    Khan, Ahmad; Khan, Jallat; Irfan, Muhammad; Naqvi, Syed Baqir Shyum; Khan, Gul Majid; Shoaib, Muhammad Harris; Yousaf, Rabia Ismail; Khan, Amjad

    2017-01-01

    The objective of this study was validation of a reverse phase HPLC method for the estimation of metoclopramide HCl in plasma already validated for determination of metoclopramide HCl in tablets dosage form. A reverse chromatographic method was used for estimation of metoclopramide HCl with the mobile phase of acetonitrile, 20mM potassium dihydrogen phosphate buffer solution (pH 3.0 adjusted with orthophosphoric acid) in the ratio of 40: 60. The column used was Waters C18 3.9×300mm µBondapak (RP). The flow rate of the mobile phase was 2ml/ minute. The detector was set at the wavelength of 275nm. This method validated in plasma and was found to be linear, with correlation coefficient (R(2)), value of 0.9988, in the range of 48 ng/ml-0.25ng/ml. The method modified was accurate, precise, sensitive and showed good stability results. The % RSD of the retention time and peak area of metoclopramide HCl was 0.19% and 1.44% respectively. All the parameters such as specificity, linearity, range, accuracy, precision, system suitability, solution stability, detection and quantification limits were evaluated to validate this method and were found within the acceptance limits. The method can be effectively used for estimation of metoclopramide HCl in plasma.

  14. 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.

  15. Application of chiral derivatizing agents in the high-performance liquid chromatographic separation of amino acid enantiomers: a review.

    PubMed

    Ilisz, István; Berkecz, Robert; Péter, Antal

    2008-05-12

    The past 20 years has seen an explosive growth in the field of chirality, as illustrated by the rapid progress in the various facets of this intriguing field. The impetus for advances in chiral separation has been highest in the past decade and this still continues to be an area of high focus. This paper reviews indirect separation approaches, i.e. derivatization reactions aimed at creating the basis for the chromatographic resolution of biologically and pharmaceutically important enantiomers, with emphasis on the literature published in the last 12 years. The main aspects of the chiral derivatization of amino acids are discussed, i.e. derivatization on the amino group, transforming the molecules into covalently bonded diastereomeric derivatives through the use of homochiral derivatizing agents. The diastereomers formed (amides, urethanes, urea, thiourea derivatives, etc.) can be separated on achiral stationary phases. The applications are considered, and in some cases different derivatizing agents for the resolution of complex mixtures of proteinogenic d,l-amino acids, non-proteinogenic amino acids and peptides/amino acids from peptide syntheses or microorganisms are compared.

  16. Recent advances in the direct and indirect liquid chromatographic enantioseparation of amino acids and related compounds: a review.

    PubMed

    Ilisz, István; Aranyi, Anita; Pataj, Zoltán; Péter, Antal

    2012-10-01

    Amino acids are essential for life, and have many functions in metabolism. One particularly important function is to serve as the building blocks of peptides and proteins, giving rise to complex three dimensional structures through disulfide bonds or crosslinked amino acids. Peptides are frequently cyclic and contain protein as well as non-protein aminoacids in many instances. Since most of the proteinogenic α-amino acids contain a chiral carbon atom (with the exception of glycine), the stereoisomers of all these amino acids and the peptides in which they are to be found may possess differences in biological activity in living systems. The impetus for advances in chiral separation has been highest in the past decade and this still continues to be an area of high focus. The important analytical task of the separation of isomers is achieved mainly by chromatographic methods. This review surveys indirect and direct HPLC separations of biologically and pharmaceutically important enantiomers of amino acids and related compounds, with emphasis on the literature published from 2005.

  17. Determination of void fraction in two phase liquid-gas flow using gamma absorption

    NASA Astrophysics Data System (ADS)

    Zych, M.; Hanus, R.; Jaszczur, M.; Strzępowicz, A.; Petryka, L.; Mastej, W.

    2016-09-01

    Full description of a two-phase liquid-gas flow requires the designation of lot parameters. First one, which describes which part of the pipeline is fulfilled by the gas, is the void fraction. Moreover the share of gas in a flowing mixture determines the structure of the flow and also affects the velocity of the individual phases. In that case void fraction can be determined by use the gamma absorption method, as well as other flow parameters may be evaluated by the same equipment. In addition the article presents the calibration of radiometric set, which consists of gamma radiation source Am-241 and scintillation probe NaI(Tl), for determination of the void fraction, illustrated by exemplary results of the described method application to various structures of air-water flow in the horizontal pipeline.

  18. Performance of short-chain alcohols versus acetonitrile in the surfactant-mediated reversed-phase liquid chromatographic separation of β-blockers.

    PubMed

    Ruiz-Ángel, M J; Torres-Lapasió, J R; Carda-Broch, S; García-Álvarez-Coque, M C

    2010-11-05

    Organic solvents are traditionally added to micellar mobile phases to achieve adequate retention times and peak profiles, in a chromatographic mode which has been called micellar liquid chromatography (MLC). The organic solvent content is limited to preserve the formation of micelles. However, at increasing organic solvent contents, the transition to a situation where micelles do not exist is gradual. Also, there is no reason to neglect the potentiality of mobile phases containing only surfactant monomers instead of micelles (high submicellar chromatography, HSC). This is demonstrated here for the analysis of β-blockers. The performance of four organic solvents (methanol, ethanol, 1-propanol, and acetonitrile) was compared in mobile phases containing the anionic surfactant sodium dodecyl sulphate in the MLC and HSC modes. The association of the organic solvent molecules with micelles gives rise to a significant loss in the elution strength of the organic solvent; whereas upon disruption of micelles, it tends to that observed in the hydro-organic mode. The elution behaviour of the β-blockers was modelled to predict the retention times. This allowed the detailed exploration of the selectivity and resolution of the chromatographic systems in relatively wide ranges of concentration of surfactant and organic solvent. The best performance in terms of resolution and analysis time was achieved using HSC with acetonitrile, being able to base-line resolve a mixture of eight β-blockers. Ethanol also provided a good separation performance, significantly improved with respect to methanol and 1-propanol. In contrast, the hydro-organic mode using acetonitrile or any of the short-chain alcohols could not succeed with the separation of the β-blockers, owing to the poorer selectivity and wider peaks.

  19. Liquid chromatographic methods for the determination of vildagliptin in the presence of its synthetic intermediate and the simultaneous determination of pioglitazone hydrochloride and metformin hydrochloride.

    PubMed

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

    2011-09-01

    Two reversed-phase liquid chromatographic (RP-LC) methods are described for the determination of two binary mixtures of hypoglycemic agents. In the first method, vildagliptin (VDG) was determined in the presence of 3-amino-1-adamantanol (AAD), a synthetic intermediate and impurity of VDG. In the second method, pioglitazone hydrochloride (PGZ) and metformin hydrochloride (MET) were simultaneously determined in their binary mixture. Chromatographic separation in the two methods was achieved on a Symmetry(®) Waters C18 column (150 mm × 4.6 mm, 5 μm). In the first mixture, isocratic elution using a mobile phase 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 was performed. In the second method, isocratic elution based on potassium dihydrogen phosphate buffer pH (4.6) - acetonitrile (60:40, v/v) at a flow rate of 1 mL min(-1) with UV detection at 210 nm was performed. Linearity, accuracy and precision were found to be acceptable over the concentration ranges of 5-200 μg mL(-1), 0.5-3 μg mL(-1) and 10-150 μg mL(-1) for VDG, PGZ and MET, respectively. The optimized methods were validated and proved to be specific, robust, precise and accurate for the quality control of the drugs in their pharmaceutical preparations.

  20. 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.