Science.gov

Sample records for liquid chromatography technique

  1. Characterisation of poly(vinyl alcohol) by liquid chromatography techniques

    SciTech Connect

    Meehan, E.; Warner, F.P.; Patterson, M.

    1995-12-01

    The molecular weight distribution of poly (vinyl alcohol) can be measured by aqueous size exclusion chromatography methods but the choice of eluent is critical in eliminating non size exclusion behavior. Aqueous size exclusion experiments have been carried out using a number of eluents including standard electrolytes and surfactants. The most favorable molecular size separation was obtained using 0.25% w/v sodium lauryl sulphate as eluent. Compositional distributions in copolymer systems can be assessed using high performance liquid chromatography employing a reverse phase separation mechanism. For poly (vinyl alcohol) gradient elution with water/tetrahydrofuran was found to produce a separation according to composition. Fast gradient elution (>10% tetrahydrofuran/minute) suggested abroad distribution of composition which was verified using a column packed with non-porous beads. Slower gradient elution (<1% tetrahydrofuran/minute) suggested that this was not due to a gradual composition change but rather discrete fractions of similarly hydrophobic material.

  2. Ribbon storage techniques for liquid chromatography: mass spectrometry

    SciTech Connect

    Smith, R.D.; Johnson, A.L.

    1981-06-01

    A new liquid chromatography-mass spectrometry (LC-MS) has been developed which allows semipermanent storage of the chromatographically separated material on a moving ribbon permitting multiple temperature analyses of a single LC separation. The new interface removes the major disadvantage of conventional moving ribbon devices by allowing analysis of a single LC separation at several different temperatures. Reconstructed ion chromatograms for the molecular ions in a standard mixture of benzopyrene, chrysene, carbazole, 7 amino-4-hydroxyquinoline, 5-hydroxyquinoline, 5-aminoquinoline, 5-hydroxy indole, and o-cresol are presented. The results are for a single injection and two passes of the separated material through desorption region at 195/sup 0/C and 285/sup 0/C. Reconstructed ion chromatograms are also presented for eight typical ions in an analysis of a biomass product for a single injection at three different ribbon passes through the flash heater.

  3. Advanced proteomic liquid chromatography

    SciTech Connect

    Xie, Fang; Smith, Richard D.; Shen, Yufeng

    2012-10-26

    Liquid chromatography coupled with mass spectrometry is the predominant platform used to analyze proteomics samples consisting of large numbers of proteins and their proteolytic products (e.g., truncated polypeptides) and spanning a wide range of relative concentrations. This review provides an overview of advanced capillary liquid chromatography techniques and methodologies that greatly improve separation resolving power and proteomics analysis coverage, sensitivity, and throughput.

  4. Column Liquid Chromatography.

    ERIC Educational Resources Information Center

    Majors, Ronald E.; And Others

    1984-01-01

    Reviews literature covering developments of column liquid chromatography during 1982-83. Areas considered include: books and reviews; general theory; columns; instrumentation; detectors; automation and data handling; multidimensional chromatographic and column switching techniques; liquid-solid chromatography; normal bonded-phase, reversed-phase,…

  5. Advanced proteomic liquid chromatography

    PubMed Central

    Xie, Fang; Smith, Richard D.; Shen, Yufeng

    2012-01-01

    Liquid chromatography coupled with mass spectrometry is the predominant platform used to analyze proteomics samples consisting of large numbers of proteins and their proteolytic products (e.g., truncated polypeptides) and spanning a wide range of relative concentrations. This review provides an overview of advanced capillary liquid chromatography techniques and methodologies that greatly improve separation resolving power and proteomics analysis coverage, sensitivity, and throughput. PMID:22840822

  6. Simultaneous analysis for water- and fat-soluble vitamins by a novel single chromatography technique unifying supercritical fluid chromatography and liquid chromatography.

    PubMed

    Taguchi, Kaori; Fukusaki, Eiichiro; Bamba, Takeshi

    2014-10-01

    Chromatography techniques usually use a single state in the mobile phase, such as liquid, gas, or supercritical fluid. Chromatographers manage one of these techniques for their purpose but are sometimes required to use multiple methods, or even worse, multiple techniques when the target compounds have a wide range of chemical properties. To overcome this challenge, we developed a single method covering a diverse compound range by means of a "unified" chromatography which completely bridges supercritical fluid chromatography and liquid chromatography. In our method, the phase state was continuously changed in the following order; supercritical, subcritical and liquid. Moreover, the gradient of the mobile phase starting at almost 100% CO2 was replaced with 100% methanol at the end completely. As a result, this approach achieved further extension of the polarity range of the mobile phase in a single run, and successfully enabled the simultaneous analysis of fat- and water-soluble vitamins with a wide logP range of -2.11 to 10.12. Furthermore, the 17 vitamins were exceptionally separated in 4min. Our results indicated that the use of dense CO2 and the replacement of CO2 by methanol are practical approaches in unified chromatography covering diverse compounds. Additionally, this is a first report to apply the novel approach to unified chromatography, and can open another door for diverse compound analysis in a single chromatographic technique with single injection, single column and single system.

  7. Vortex-assisted liquid-liquid-liquid microextraction (VALLLME) technique: A new microextraction approach for direct liquid chromatography and capillary electrophoresis analysis.

    PubMed

    Makahleh, Ahmad; Yap, Hui Fang; Saad, Bahruddin

    2015-10-01

    A new, rapid and sensitive microextraction technique named vortex-assisted liquid-liquid-liquid microextraction (VALLLME) is proposed. The complete extraction process involves two steps. First, a vortex-assisted liquid-liquid microextraction (VALLME) procedure was used to extract the analytes from a relatively large volume of sample (donor phase) to a small volume of organic solvent (intermediate phase). Next, a micro-vortex-assisted liquid-liquid extraction (µ-VALLE) was used to extract the target analytes from the intermediate phase to a smaller volume of aqueous solution (acceptor phase). The final extract (acceptor phase) can be directly injected into the high performance liquid chromatography or capillary electrophoresis units without any further treatments. The selection of the intermediate phase and the manipulation of pH are key parameters that ensure good extraction efficiency of the technique. The proposed technique has been successfully applied for the determination of carvedilol (used as model analyte) in biological fluid samples. The optimum extraction conditions were: toluene as intermediate phase (150 μL); pH of the donor phase, 9.5; vortex time of the VALLME, 45 s (maximum speed, 2500 rpm); 0.1M HCl (15 μL) as acceptor phase; vortexing time of the µ-VALLME, 75 s (maximum stirring speed, 2500 rpm) and salt concentration in the donor phase, 5% (w/v). Under these conditions, enrichment factors of 51- and 418-fold for VALLME step and VALLLME procedure, respectively, were achieved. PMID:26078176

  8. High-Performance Liquid Chromatography

    NASA Astrophysics Data System (ADS)

    Reuhs, Bradley L.; Rounds, Mary Ann

    High-performance liquid chromatography (HPLC) developed during the 1960s as a direct offshoot of classic column liquid chromatography through improvements in the technology of columns and instrumental components (pumps, injection valves, and detectors). Originally, HPLC was the acronym for high-pressure liquid chromatography, reflecting the high operating pressures generated by early columns. By the late 1970s, however, high-performance liquid chromatography had become the preferred term, emphasizing the effective separations achieved. In fact, newer columns and packing materials offer high performance at moderate pressure (although still high pressure relative to gravity-flow liquid chromatography). HPLC can be applied to the analysis of any compound with solubility in a liquid that can be used as the mobile phase. Although most frequently employed as an analytical technique, HPLC also may be used in the preparative mode.

  9. Liquid chromatography and supercritical fluid chromatography as alternative techniques to gas chromatography for the rapid screening of anabolic agents in urine.

    PubMed

    Desfontaine, Vincent; Nováková, Lucie; Ponzetto, Federico; Nicoli, Raul; Saugy, Martial; Veuthey, Jean-Luc; Guillarme, Davy

    2016-06-17

    This work describes the development of two methods involving supported liquid extraction (SLE) sample treatment followed by ultra-high performance liquid chromatography or ultra-high performance supercritical fluid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS and UHPSFC-MS/MS) for the screening of 43 anabolic agents in human urine. After evaluating different stationary phases, a polar-embedded C18 and a diol columns were selected for UHPLC-MS/MS and UHPSFC-MS/MS, respectively. Sample preparation, mobile phases and MS conditions were also finely tuned to achieve highest selectivity, chromatographic resolution and sensitivity. Then, the performance of these two methods was compared to the reference routine procedure for steroid analyses in anti-doping laboratories, which combines liquid-liquid extraction (LLE) followed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). For this purpose, urine samples spiked with the compounds of interest at five different concentrations were analyzed using the three analytical platforms. The retention and selectivity of the three techniques were very different, ensuring a good complementarity. However, the two new methods displayed numerous advantages. The overall procedure was much faster thanks to high throughput SLE sample treatment using 48-well plates and faster chromatographic analysis. Moreover, the highest sensitivity was attained using UHPLC-MS/MS with 98% of the doping agents detected at the lowest concentration level (0.1ng/mL), against 76% for UHPSFC-MS/MS and only 14% for GC-MS/MS. Finally, the weakest matrix effects were obtained with UHPSFC-MS/MS with 76% of the analytes displaying relative matrix effect between -20 and 20%, while the GC-MS/MS reference method displayed very strong matrix effects (over 100%) for all of the anabolic agents.

  10. Liquid chromatography and supercritical fluid chromatography as alternative techniques to gas chromatography for the rapid screening of anabolic agents in urine.

    PubMed

    Desfontaine, Vincent; Nováková, Lucie; Ponzetto, Federico; Nicoli, Raul; Saugy, Martial; Veuthey, Jean-Luc; Guillarme, Davy

    2016-06-17

    This work describes the development of two methods involving supported liquid extraction (SLE) sample treatment followed by ultra-high performance liquid chromatography or ultra-high performance supercritical fluid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS and UHPSFC-MS/MS) for the screening of 43 anabolic agents in human urine. After evaluating different stationary phases, a polar-embedded C18 and a diol columns were selected for UHPLC-MS/MS and UHPSFC-MS/MS, respectively. Sample preparation, mobile phases and MS conditions were also finely tuned to achieve highest selectivity, chromatographic resolution and sensitivity. Then, the performance of these two methods was compared to the reference routine procedure for steroid analyses in anti-doping laboratories, which combines liquid-liquid extraction (LLE) followed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). For this purpose, urine samples spiked with the compounds of interest at five different concentrations were analyzed using the three analytical platforms. The retention and selectivity of the three techniques were very different, ensuring a good complementarity. However, the two new methods displayed numerous advantages. The overall procedure was much faster thanks to high throughput SLE sample treatment using 48-well plates and faster chromatographic analysis. Moreover, the highest sensitivity was attained using UHPLC-MS/MS with 98% of the doping agents detected at the lowest concentration level (0.1ng/mL), against 76% for UHPSFC-MS/MS and only 14% for GC-MS/MS. Finally, the weakest matrix effects were obtained with UHPSFC-MS/MS with 76% of the analytes displaying relative matrix effect between -20 and 20%, while the GC-MS/MS reference method displayed very strong matrix effects (over 100%) for all of the anabolic agents. PMID:27185056

  11. Liquid Chromatography in 1982.

    ERIC Educational Resources Information Center

    Freeman, David H.

    1982-01-01

    Reviews trends in liquid chromatography including apparatus, factors affecting efficient separation of a mixture (peak sharpness and speed), simplified problem-solving, adsorption, bonded phase chromatography, ion selectivity, and size exclusion. The current trend is to control chemical selectivity by the liquid phase. (Author/JN)

  12. Gradient enhanced-fluidity liquid hydrophilic interaction chromatography of ribonucleic acid nucleosides and nucleotides: A "green" technique.

    PubMed

    Beilke, Michael C; Beres, Martin J; Olesik, Susan V

    2016-03-01

    A "green" hydrophilic interaction liquid chromatography (HILIC) technique for separating the components of mixtures with a broad range of polarities is illustrated using enhanced-fluidity liquid mobile phases. Enhanced-fluidity liquid chromatography (EFLC) involves the addition of liquid CO2 to conventional liquid mobile phases. Decreased mobile phase viscosity and increased analyte diffusivity results when a liquefied gas is dissolved in common liquid mobile phases. The impact of CO2 addition to a methanol:water (MeOH:H2O) mobile phase was studied to optimize HILIC gradient conditions. For the first time a fast separation of 16 ribonucleic acid (RNA) nucleosides/nucleotides was achieved (16min) with greater than 1.3 resolution for all analyte pairs. By using a gradient, the analysis time was reduced by over 100% compared to similar separations conducted under isocratic conditions. The optimal separation using MeOH:H2O:CO2 mobile phases was compared to MeOH:H2O and acetonitrile:water (ACN:H2O) mobile phases. Based on chromatographic performance parameters (efficiency, resolution and speed of analysis) and an assessment of the environmental impact of the mobile phase mixtures, MeOH:H2O:CO2 mixtures are preferred over ACN:H2O or MeOH:H2O mobile phases for the separation of mixtures of RNA nucleosides and nucleotides.

  13. A novel fully automated on-line coupled liquid chromatography-gas chromatography technique used for the determination of organochlorine pesticide residues in tobacco and tobacco products.

    PubMed

    Qi, Dawei; Fei, Ting; Sha, Yunfei; Wang, Leijun; Li, Gang; Wu, Da; Liu, Baizhan

    2014-12-29

    In this study, a novel fully automated on-line coupled liquid chromatography-gas chromatography (LC-GC) technique was reported and applied for the determination of organochlorine pesticide residues (OCPs) in tobacco and tobacco products. Using a switching valve to isolate the capillary pre-column and the analytical column during the solvent evaporation period, the LC solvent can be completely removed and prevented from reaching the GC column and the detector. The established method was used to determinate the OCPs in tobacco samples. By using Florisil SPE column and employing GPC technique, polarity impurities and large molecule impurities were removed. A dynamic range 1-100ng/mL was achieved with detection limits from 1.5 to 3.3μg/kg. The method exhibited good repeatability and recoveries. This technology may provide an alternative way for trace analysis of complex samples.

  14. Mixed Stationary Liquid Phases for Gas-Liquid Chromatography.

    ERIC Educational Resources Information Center

    Koury, Albert M.; Parcher, Jon F.

    1979-01-01

    Describes a laboratory technique for use in an undergraduate instrumental analysis course that, using the interpretation of window diagrams, prepares a mixed liquid phase column for gas-liquid chromatography. A detailed procedure is provided. (BT)

  15. High Performance Liquid Chromatography Experiments to Undergraduate Laboratories

    ERIC Educational Resources Information Center

    Kissinger, Peter T.; And Others

    1977-01-01

    Reviews the principles of liquid chromatography with electrochemical detection (LCEC), an analytical technique that incorporates the advantages of both liquids chromatography and electrochemistry. Also suggests laboratory experiments using this technique. (MLH)

  16. High Performance Liquid Chromatography

    NASA Astrophysics Data System (ADS)

    Talcott, Stephen

    High performance liquid chromatography (HPLC) has many applications in food chemistry. Food components that have been analyzed with HPLC include organic acids, vitamins, amino acids, sugars, nitrosamines, certain pesticides, metabolites, fatty acids, aflatoxins, pigments, and certain food additives. Unlike gas chromatography, it is not necessary for the compound being analyzed to be volatile. It is necessary, however, for the compounds to have some solubility in the mobile phase. It is important that the solubilized samples for injection be free from all particulate matter, so centrifugation and filtration are common procedures. Also, solid-phase extraction is used commonly in sample preparation to remove interfering compounds from the sample matrix prior to HPLC analysis.

  17. Microextraction techniques coupled to liquid chromatography with mass spectrometry for the determination of organic micropollutants in environmental water samples.

    PubMed

    Padrón, Ma Esther Torres; Afonso-Olivares, Cristina; Sosa-Ferrera, Zoraida; Santana-Rodríguez, José Juan

    2014-01-01

    Until recently, sample preparation was carried out using traditional techniques, such as liquid-liquid extraction (LLE), that use large volumes of organic solvents. Solid-phase extraction (SPE) uses much less solvent than LLE, although the volume can still be significant. These preparation methods are expensive, time-consuming and environmentally unfriendly. Recently, a great effort has been made to develop new analytical methodologies able to perform direct analyses using miniaturised equipment, thereby achieving high enrichment factors, minimising solvent consumption and reducing waste. These microextraction techniques improve the performance during sample preparation, particularly in complex water environmental samples, such as wastewaters, surface and ground waters, tap waters, sea and river waters. Liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS) and time-of-flight mass spectrometric (TOF/MS) techniques can be used when analysing a broad range of organic micropollutants. Before separating and detecting these compounds in environmental samples, the target analytes must be extracted and pre-concentrated to make them detectable. In this work, we review the most recent applications of microextraction preparation techniques in different water environmental matrices to determine organic micropollutants: solid-phase microextraction SPME, in-tube solid-phase microextraction (IT-SPME), stir bar sorptive extraction (SBSE) and liquid-phase microextraction (LPME). Several groups of compounds are considered organic micropollutants because these are being released continuously into the environment. Many of these compounds are considered emerging contaminants. These analytes are generally compounds that are not covered by the existing regulations and are now detected more frequently in different environmental compartments. Pharmaceuticals, surfactants, personal care products and other chemicals are considered micropollutants. These compounds must be

  18. High-performance liquid chromatography.

    PubMed

    Clevett, K J

    1990-01-01

    Gas chromatography has developed over the past 25 years or so into one of the most extensively used on-line analytical techniques in industrial process control and optimization. Liquid chromatography, and its several individual techniques, is firmly established in the laboratory, but its on-line process use has not developed as rapidly as GC. At the present time, only three companies (Applied Automation Inc., Dionex Corp., and Millipore Corp.) are active in this area. Nevertheless, substantial growth in on-line process LC is predicted for the next few years. The techniques of HPLC (normal-phase and reversed-phase), IEC, and SEC have great potential in industry as on-line analytical techniques, including the new field of biotechnology. Computer-based, multistream, multicomponent systems should find extensive use in pilot-plant investigations, where their ability to gather large amounts of data (on-line rather than by laboratory testing) could have important implications. In bioprocess control, undoubtedly the greatest challenge will come in the area of sample-handling technique. On-line chromatography has traditionally involved the sampling and conditioning of fairly conventional process gases and liquids. One exception is in the plastics and elastomers areas, where on-line SEC has been used for polymer MWD measurement. Here the sample is more difficult to handle, and some specialized techniques have been used. In biotechnology, we are treading new ground; nevertheless, it is hoped that some of the experience in sample handling gained in industry over the past 25 years will be of use in this new field.

  19. [THE TECHNIQUE OF HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY FOR SIMULTANEOUS DIAGNOSTIC OF INHERENT HYPERPLASIA OF ADRENAL GLANDS TYPE I AND II].

    PubMed

    Dutov, A A; Nikitin, D A; Lukyanova, Yu L; Shemiakina, N A

    2016-01-01

    The article considers the technique of high-performance liquid chromatography making it possible simultaneously detect cortisol, cortisone and secondary steroids in serum for consequent analysis of common reversed-phase high-performance liquid chromatography with ultraviolet under 240 nm. The liquid-liquid extraction from alkaline medium in diethyl ether The separation using column of 150x4.6 size ODS 3.5 mkm in isocratic mode. The eluent acetonitrile--0.02 M phosphate buffer pH 8.0--isopropanol (40:60:1). The application of proposed technique managed to separate cortisol, cortisone, dexamethasone, corticosterone, 11-desoxicortisol, testosterone, desoxicorticosterone, 17α-gidroxiprogesterone and androstendion in 20 minutes. The simplicity, reproducibility and sufficient selectivity and sensitivity of technique permit implement it in clinical practice for simultaneous diagnostic of inherent hyperplasia of adrenal glands type I and II. PMID:27183726

  20. [THE TECHNIQUE OF HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY FOR SIMULTANEOUS DIAGNOSTIC OF INHERENT HYPERPLASIA OF ADRENAL GLANDS TYPE I AND II].

    PubMed

    Dutov, A A; Nikitin, D A; Lukyanova, Yu L; Shemiakina, N A

    2016-01-01

    The article considers the technique of high-performance liquid chromatography making it possible simultaneously detect cortisol, cortisone and secondary steroids in serum for consequent analysis of common reversed-phase high-performance liquid chromatography with ultraviolet under 240 nm. The liquid-liquid extraction from alkaline medium in diethyl ether The separation using column of 150x4.6 size ODS 3.5 mkm in isocratic mode. The eluent acetonitrile--0.02 M phosphate buffer pH 8.0--isopropanol (40:60:1). The application of proposed technique managed to separate cortisol, cortisone, dexamethasone, corticosterone, 11-desoxicortisol, testosterone, desoxicorticosterone, 17α-gidroxiprogesterone and androstendion in 20 minutes. The simplicity, reproducibility and sufficient selectivity and sensitivity of technique permit implement it in clinical practice for simultaneous diagnostic of inherent hyperplasia of adrenal glands type I and II.

  1. Dispersive liquid-liquid microextraction followed by high-performance liquid chromatography-diode array detection as an efficient and sensitive technique for determination of antioxidants.

    PubMed

    Farajzadeh, Mir Ali; Bahram, Morteza; Jönsson, Jan Ake

    2007-05-15

    Dispersive liquid-liquid microextraction (DLLME) and high performance liquid chromatography-diode array detection (HPLC-DAD) was presented for extraction and determination of Irganox 1010, Irganox 1076 and Irgafos 168 (antioxidants) in aqueous samples. Carbon tetrachloride at microliter volume level and acetonitrile were used as extraction and dispersive solvents, respectively. The main advantages of method are high speed, high enrichment factor, high recovery, good repeatability and extraction solvent volume at microL level. Limit of detection for analytes is between 3 and 7 ng mL(-1). One variable at a time optimization and response surface modeling were used to obtain optimum conditions for microextraction procedure and nearly same experimental conditions were obtained using both optimization methods. Recoveries in the ranges 78-86% and 84-110% were obtained by one variable at a time and response surface modeling, respectively. Using tap water and packed water as matrices do not show any detrimental effect on the extraction recoveries and enrichment factors of analytes.

  2. Determination of bevantolol in human plasma by high performance liquid chromatography using solid phase extraction technique.

    PubMed

    Trung, Tran Quoc; Long, Pham Hai; Al-Abd, Ahmed M; Ku, Hyo Jeong; Lee, Ho Yoon; Hwang, Sung Joo; Kim, Kyeong Ho

    2007-07-01

    A method was developed and fully validated for the determination of bevantolol, an adrenergic-receptor blocker, in human plasma. Bevantolol and betaxolol as internal standard (I.S) were extracted from 1 mL of human plasma by solid phase extraction technique using Sep-pak silica cartridge. Chromatographic separation was accomplished under isocratic conditions using a reverse-phase C8 analytical column and mixture of dibasic ammonium phosphate (pH 5.7; 50 mM)-acetonitrile (75:25, v/v) as mobile phase, with a detection wavelength at 220 nm. The method was proved to be specific by testing six different human plasma sources. Linearity was established for the concentration ranges of 40-1600 ng/mL with correlation coefficent of 0.9995. The lower limit of quantification 40 ng/mL with precision of 10.9% as C.V%.

  3. Vortex-assisted hollow fibre liquid-phase microextraction technique combined with high performance liquid chromatography-diode array detection for the determination of oestrogens in milk samples.

    PubMed

    Wang, Peijin; Xiao, Yu; Liu, Wenjun; Wang, Juan; Yang, Yaling

    2015-04-01

    A rapid, simple, sensitive and environmentally friendly method has been developed for the determination of three oestrogens (17β-estradiol (17β-E2), estrone (E1), and diethylstilbestrol (DES)) in milk samples by using vortex-assisted hollow fibre liquid-phase microextraction (VA-HF-LPME) and high performance liquid chromatography. Method is based on the microextraction of oestrogens from sample solution into 15 μL of nonanoic acid as extracting agent, which is placed inside the hollow fibre followed by vortex-mixing. Vortex provided effective and mild mixing of sample solution and increased the contact between analytes and boundary layers of the hollow fibre, thereby enhancing mass transfer rate and leading to high recovery of target analytes. The extraction equilibrium is achieved within 2 min. Parameters influencing the recovery were investigated and optimized. The proposed technique provided good linearity (>0.9984), repeatability (RSD = 2.56-4.38), low limits of detection (0.06-0.17 ng mL(-1)), and high enrichment factor (330).

  4. A Simple and Universal Gel Permeation Chromatography Technique for Precise Molecular Weight Characterization of Well-Defined Poly(ionic liquid)s

    SciTech Connect

    He, Hongkun; Zhong, Mingjiang; Adzima, Brian; Luebke, David; Nulwala, Hunaid; Matyjaszewski, Krzysztof

    2013-03-20

    Poly(ionic liquid)s (PILs) are an important class of technologically relevant materials. However, characterization of well-defined polyionic materials remains a challenge. Herein, we have developed a simple and versatile gel permeation chromatography (GPC) methodology for molecular weight (MW) characterization of PILs with a variety of anions. PILs with narrow MW distributions were synthesized via atom transfer radical polymerization, and the MWs obtained from GPC were further confirmed via nuclear magnetic resonance end group analysis.

  5. Gel permeation chromatography-high performance liquid chromatography combination as an automated clean-up technique for the multiresidue analysis of fats.

    PubMed

    Rimkus, G G; Rummler, M; Nausch, I

    1996-06-14

    The well-known and almost universally utilizable clean-up technique of gel permeation chromatography (GPC) and subsequent conventional silica-gel column chromatography was automated by an on-line solvent evaporation of the GPC fraction, followed by normal-phase HPLC separation. The ternary solvent system n-hexane-toluene-acetone (88:10:2, v/v/v) was used as the mobile phase which resulted in only one HPLC fraction for all relevant analytes. The HPLC column was cleaned automatically after each sample by backflushing with polar solvents. The recoveries and reproducibilities of 35 analytes (mainly organochlorine compounds) were in the range of 77-90% and 3-7%, respectively; the high efficiency of the HPLC separation provide very clean extracts for the GC analysis. This automated clean-up technique is routinely used for the multiresidue analysis of various fat-containing food and biota samples.

  6. Determination of the triacylglycerol fraction in fish oil by comprehensive liquid chromatography techniques with the support of gas chromatography and mass spectrometry data.

    PubMed

    Beccaria, Marco; Costa, Rosaria; Sullini, Giuseppe; Grasso, Elisa; Cacciola, Francesco; Dugo, Paola; Mondello, Luigi

    2015-07-01

    Fish oil made from menhaden (Brevoortia tyrannus) can be used as a dietary supplement for the presence of high levels of the long-chained omega-3 fatty acids, viz. epentaenoic and docosahexanoic. In this work, for the first time, two different multidimensional approaches were developed and compared, in terms of peak capacity, for triacylglycerol characterization. In particular, silver ion chromatography with a silver-ion column and non-aqueous reverse-phase liquid chromatography with a C18 column were tested in both comprehensive (stop-flow) and off-line modes. The use of mass spectra attained by atmospheric pressure chemical ionization for both LC approaches, and the fatty acids methyl esters profile of menhaden oil obtained by gas chromatography analysis, greatly supported the elucidation of the triacylglycerol content in menhaden oil. The off-line approach afforded a better separation and, thus, higher peak capacity to allow identifying and semiquantifying more than 250 triacylglycerols. Such a huge number has never been reported for a menhaden oil sample.The main disadvantage of such an approach over the stop-flow one was the longer analysis time, mainly attributable to solvent exchange between the two dimensions. PMID:25963648

  7. Novel one-step headspace dynamic in-syringe liquid phase derivatization-extraction technique for the determination of aqueous aliphatic amines by liquid chromatography with fluorescence detection.

    PubMed

    Muniraj, Sarangapani; Shih, Hou-Kung; Chen, Ying-Fang; Hsiech, Chunming; Ponnusamy, Vinoth Kumar; Jen, Jen-Fon

    2013-06-28

    A novel one-step headspace (HS) dynamic in-syringe (DIS) based liquid-phase derivatization-extraction (LPDE) technique has been developed for the selective determination of two short-chain aliphatic amines (SCAAs) in aqueous samples using high performance liquid chromatography (HPLC) with fluorescence detection (FLD). Methylamine (MA) and dimethylamine (DMA) were selected as model compounds of SCAAs. In this method, a micro-syringe pre-filled with derivatizing reagent solution (9-fluorenylmethyl chloroformate) in the barrel was applied to achieve the simultaneous derivatization and extraction of two methylamines evolved from alkalized aqueous samples through the automated reciprocated movements of syringe plunger. After the derivatization-extraction process, the derivatized phase was directly injected into HPLC-FLD for analysis. Parameters influencing the evolution of methylamines and the HS-DIS-LPDE efficiency, including sample pH and temperature, sampling time, as well as the composition of derivatization reagent, reaction temperature, and frequency of reciprocated plunger movements, were thoroughly examined and optimized. Under optimal conditions, detections were linear in the range of 25-500μgL(-1) for MA and DMA with correlation coefficients all above 0.995. The limits of detection (based on S/N=3) were 5 and 19ngmL(-1) for MA and DMA, respectively. The applicability of the developed method was demonstrated for the determination of MA and DMA in real water samples without any prior cleanup of the sample. The present method provides a simple, selective, automated, low cost and eco-friendly procedure to determine aliphatic amines in aqueous samples. PMID:23591526

  8. Use of high pressure liquid chromatography in the study of liquid lubricant oxidation

    NASA Technical Reports Server (NTRS)

    Morales, W.

    1982-01-01

    The general principles of classical liquid chromatography and high-pressure liquid chromatography (HPLC) are reviewed, and their advantages and disadvantages are compared. Several chromatographic techniques are reviewed, and the analysis of a C-ether liquid lubricant by each technique is illustrated. An analysis by size exclusion chromatography of an ester lubricant, which had been degraded using a micro-oxidation apparatus, is illustrated to show how HPLC can be used in the study of high-temperature lubricant degradation.

  9. High-performance liquid chromatography as a technique to determine protein adsorption onto hydrophilic/hydrophobic surfaces.

    PubMed

    Huang, Tongtong; Anselme, Karine; Sarrailh, Segolene; Ponche, Arnaud

    2016-01-30

    The purpose of this study is to evaluate the potential of simple high performance liquid chromatography (HPLC) setup for quantification of adsorbed proteins on various type of plane substrates with limited area (<3 cm(2)). Protein quantification was investigated with a liquid chromatography chain equipped with a size exclusion column or a reversed-phase column. By evaluating the validation of the method according to guidelines of the International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH), all the results obtained by HPLC were reliable. By simple adsorption test at the contact of hydrophilic (glass) and hydrophobic (polydimethylsiloxane: PDMS) surfaces, kinetics of adsorption were determined and amounts of adsorbed bovine serum albumin, myoglobin and lysozyme were obtained: as expected for each protein, the amount adsorbed at the plateau on glass (between 0.15 μg/cm(2) and 0.4 μg/cm(2)) is lower than for hydrophobic PDMS surfaces (between 0.45 μg/cm(2) and 0.8 μg/cm(2)). These results were consistent with bicinchoninic acid protein determination. According to ICH guidelines, both Reversed Phase and Size Exclusion HPLC can be validated for quantification of adsorbed protein. However, we consider the size exclusion approach more interesting in this field because additional informations can be obtained for aggregative proteins. Indeed, monomer, dimer and oligomer of bovine serum albumin (BSA) were observed in the chromatogram. On increasing the temperature, we found a decrease of peak intensity of bovine serum albumin as well as the fraction of dimer and oligomer after contact with PDMS and glass surface. As the surface can act as a denaturation parameter, these informations can have a huge impact on the elucidation of the interfacial behavior of protein and in particular for aggregation processes in pharmaceutical applications.

  10. Instrument platforms for nano liquid chromatography.

    PubMed

    Šesták, Jozef; Moravcová, Dana; Kahle, Vladislav

    2015-11-20

    The history of liquid chromatography started more than a century ago and miniaturization and automation are two leading trends in this field. Nanocolumn liquid chromatography (nano LC) and largely synonymous capillary liquid chromatography (capillary LC) are the most recent results of this process where miniaturization of column dimensions and sorbent particle size play crucial role. Very interesting results achieved in the research of extremely miniaturized LC columns at the end of the last century lacked distinctive raison d'être and only advances in mass spectrometry brought a real breakthrough. Configuration of nano LC-electrospray ionization mass spectrometry (LC-ESI-MS) has become a basic tool in bioanalytical chemistry, especially in proteomics. This review discusses and summarizes past and current trends in the realization of nano liquid chromatography (nano LC) platforms. Special attention is given to the mobile phase delivery under nanoflow rates (isocratic, gradient) and sample injection to the nanocolumn. Available detection techniques applied in nano LC separations are also briefly discussed. We followed up the key themes from the original scientific reports over gradual improvements up to the contemporary commercial solutions.

  11. Capillary action liquid chromatography.

    PubMed

    Zhang, Bo; Bergström, Edmund T; Goodall, David M; Myers, Peter

    2009-06-01

    Capillary action LC (caLC) is introduced as a technique using capillary action as the driving force to perform LC in capillary columns packed with HPLC type microparticulate materials. A dry packing method with centrifugal force was developed to prepare capillary columns in parallel (10 columns per 3 min) to support their disposable use in caLC. Using a digital microscope for real-time imaging and recording separations of components in a dye mixture, caLC was found to have flow characteristics similar to TLC. Based on the investigation of microparticulate HPLC silica gels of different size (1.5-10 microm) and a typical TLC grade irregular medium, Merck 60G silica, the van Deemter curves suggested molecular diffusion as the major contribution to band broadening in caLC. With Waters Xbridge 2.6 microm silica, plate heights down to 8.8 microm were obtained, comparable to those achievable in HPLC. Assisted by an image-processing method, the visual caLC separation was converted to a classical chromatogram for further data analysis and such a facility confirmed the observation of highly efficient bands.

  12. Liquid-liquid/solid three-phase high-speed counter-current chromatography, a new technique for separation of polyphenols from Geranium wilfordii Maxim.

    PubMed

    Liu, Dan; Ma, Yan; Gu, Ming; Janson, Jan-Christer; Wang, Changhai; Xiao, Hongbin

    2012-08-01

    High-speed counter-current chromatography using a new liquid-liquid/solid three-phase system was used for the separation of the polyphenols corilagin and geraniin from a crude extract of Geranium wilfordii Maxim in one step. The optimized three-phase system was composed of n-hexane/ethyl acetate/methanol/acetic acid/water and to which was added 10-μm average diameter microspheres of cross-linked 12% agarose at the ratio of 0.2:10:2:1:5 and 0.1 g/mL, respectively. The purities of geraniin and corilagin were 82 and 90%, which were determined by HPLC at 280 nm. A 14.5 and 7 mg of geraniin and corilagin were purified from 160 mg crude extract with the yields of 70 and 78%, respectively.

  13. Metabolite analysis of toosendanin by an ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry technique.

    PubMed

    Wu, Jian-Lin; Leung, Elaine Lai-Han; Zhou, Hua; Liu, Liang; Li, Na

    2013-01-01

    Toosendanin is the major bioactive component of Melia toosendan Sieb. et Zucc., which is traditionally used for treatment of abdominal pain and as an insecticide. Previous studies reported that toosendanin possesses hepatotoxicity, but the mechanism remains unknown. Its bioavailability in rats is low, which indicates the hepatotoxicity might be induced by its metabolites. In this connection, in the current study, we examined the metabolites obtained by incubating toosendanin with human live microsomes, and then six of these metabolites (M1-M6) were identified for the first time by ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry (UHPLC-Q-TOF/MS). Further analysis on the MS spectra showed M1, M2, and M3 are oxidative products and M6 is a dehydrogenation product, while M4 and M5 are oxidative and dehydrogenation products of toosendanin. Moreover, their possible structures were deduced from the MS/MS spectral features. Quantitative analysis demonstrated that M1-M5 levels rapidly increased and reached a plateau at 30 min, while M6 rapidly reached a maximal level at 20 min and then decreased slowly afterwards. These findings have provided valuable data not only for understanding the metabolic fate of toosendanin in liver microsomes, but also for elucidating the possible molecular mechanism of its hepatotoxicity. PMID:24084018

  14. Simultaneous Quantitative Analysis of Olmesartan Medoxomil and Amlodipine Besylate in Plasma by High-performance Liquid Chromatography Technique

    PubMed Central

    Shah, SK; Asnani, AJ; Kawade, DP; Dangre, SC; Arora, SK; Yende, SR

    2012-01-01

    A rapid, simple and sensitive high-performance liquid chromatography (HPLC) method has been developed for quantification of olmesartan medoxomil (OLM) and amlodipine besylate (AM) in plasma. The assay enables the measurement of OLM and AM for therapeutic drug monitoring with a minimum detectable limit of 2 ng mL. The method involves a simple, one-step extraction procedure and analytical recovery was above 50%. The separation was performed on an analytical 250 × 4.6 mm Eurospher 100-5 C18 column. The wavelength was set at 239 nm. The mobile phase was a mixture of acetonitrile:0.05 M ammonium acetate buffer: 0.1 mL triethylamine at pH 6.8 was selected at a flow rate of 1.0 mL min. The calibration curve for the determination of OLM and AM in plasma was linear over the range 2–2500 and 8–10,000 ng mL AM and OLM. The coefficients of variation for interday and intraday assay were found to be <15%. The method can be applied to a pharmacokinetic and pharmacodynamic study of OLM and AM in a combined dosage form. PMID:22754260

  15. Direct and comprehensive analysis of ginsenosides and diterpene alkaloids in Shenfu injection by combinatory liquid chromatography-mass spectrometric techniques.

    PubMed

    Yang, Hua; Liu, Lei; Gao, Wen; Liu, Ke; Qi, Lian-Wen; Li, Ping

    2014-04-01

    Shenfu injection (SFI) is a widely used Chinese herbal formulation for cardiac diseases prepared from red ginseng and processed aconite root. Clinical observations and pharmacological effects on SFI have been well investigated. Chemical analysis and quality control studies of this formulation, however, are relatively limited, especially regarding toxic aconite alkaloids. In this work, a high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (HPLC-QTOF MS) method was applied to comprehensive analysis of constituents in SFI. Highly sensitive MS allows direct analysis of injections without additional sample pretreatment required. Using diagnostic ions and fragmentation rules, we identified 23 trace diterpene alkaloids, nineteen ginseng saponins, one panaxytriol, and one 5-hydroxymethylfurfural in SFI. A LC-MS method with selected ion monitoring was then used to quantify 24 major alkaloids and ginsenosides. The method was validated in terms of linearity, accuracy and precision. Especially, the limits of quantification were low to 0.4-18ng/mL for diterpene alkaloids. The total concentrations of saponins and alkaloids were about 676-742μg/mL and 3-7μg/mL in five batches of SFI samples, respectively. Finally, cosine ratio and euclidean distance were introduced to evaluate the batch-to-batch reproducibility of SFI samples, and the results demonstrated high quality consistency. Global identification and quantification of complex constituents based on LC-MS promises wide applications in quality control and batch monitoring for herbal products.

  16. Liquid-phase chromatography detector

    DOEpatents

    Voigtman, E.G.; Winefordner, J.D.; Jurgensen, A.R.

    1983-11-08

    A liquid-phase chromatography detector comprises a flow cell having an inlet tubular conduit for receiving a liquid chromatographic effluent and discharging it as a flowing columnar stream onto a vertically adjustable receiving surface spaced apart from and located vertically below and in close proximity to the discharge end of the tubular conduit; a receiver adapted to receive liquid overflowing from the receiving surface; an exit conduit for continuously removing liquid from the receiver; a light source for focusing fluorescence-producing light pulses on the flowing columnar stream as it passes from the outlet of the conduit to the receiving surface and a fluorescence detector to detect the produced fluorescence; a source of light pulse for producing acoustic waves in the columnar stream as it passes from the conduit outlet to the receiving surface; and a piezoelectric transducer adapted to detect those waves; and a source of bias voltage applied to the inlet tubular conduit and adapted to produce ionization of the liquid flowing through the flow cell so as to produce photocurrents therein and an electrical system to detect and record the photocurrents. This system is useful in separating and detecting individual chemical compounds from mixtures thereof. 5 figs.

  17. Liquid-phase chromatography detector

    DOEpatents

    Voigtman, Edward G.; Winefordner, James D.; Jurgensen, Arthur R.

    1983-01-01

    A liquid-phase chromatography detector comprising a flow cell having an inlet tubular conduit for receiving a liquid chromatographic effluent and discharging it as a flowing columnar stream onto a vertically adjustable receiving surface spaced apart from and located vertically below and in close proximity to the discharge end of the tubular conduit; a receiver adapted to receive liquid overflowing from the receiving surface; an exit conduit for continuously removing liquid from the receiver; a light source for focussing fluorescence-producing light pulses on the flowing columnar stream as it passes from the outlet of the conduit to the receiving surface and a fluorescence detector to detect the produced fluorescence; a source of light pulse for producing acoustic waves in the columnar stream as it passes from the conduit outlet to the receiving surface; and a piezoelectric transducer adapted to detect those waves; and a source of bias voltage applied to the inlet tubular conduit and adapted to produce ionization of the liquid flowing through the flow cell so as to produce photocurrents therein and an electrical system to detect and record the photocurrents. This system is useful in separating and detecting individual chemical compounds from mixtures thereof.

  18. When other separation techniques fail: compound-specific carbon isotope ratio analysis of sulfonamide containing pharmaceuticals by high-temperature-liquid chromatography-isotope ratio mass spectrometry.

    PubMed

    Kujawinski, Dorothea M; Zhang, Lijun; Schmidt, Torsten C; Jochmann, Maik A

    2012-09-18

    Compound-specific isotope analysis (CISA) of nonvolatile analytes has been enabled by the introduction of the first commercial interface to hyphenate liquid chromatography with an isotope ratio mass spectrometer (LC-IRMS) in 2004, yet carbon isotope analysis of unpolar and moderately polar compounds is still a challenging task since only water as the eluent and no organic modifiers can be used to drive the separation in LC. The only way to increase the elution strength of aqueous eluents in reversed phase LC is the application of high temperatures to the mobile and stationary phases (HT-LC-IRMS). In this context we present the first method to determine carbon isotope ratios of pharmaceuticals that cannot be separated by already existing separation techniques for LC-IRMS, such as reversed phase chromatography at normal temperatures, ion-chromatography, and mixed mode chomatography. The pharmaceutical group of sulfonamides, which is generally mixed with trimethoprim in pharmaceutical products, has been chosen as probe compounds. Substance amounts as low as 0.3 μg are sufficient to perform a precise analysis. The successful applicability and reproducibility of this method is shown by the analysis of real pharmaceutical samples. The method provides the first tool to study the pharmaceutical authenticity as well as degradation and mobility of such substances in the environment by using the stable isotopic signature of these compounds.

  19. Validation of a new liquid chromatography- tandem mass spectrometry ion-trap technique for the simultaneous determination of thirteen anticoagulant rodenticides, drugs, or natural products.

    PubMed

    Fourel, Isabelle; Hugnet, Christophe; Goy-Thollot, Isabelle; Berny, Philippe

    2010-03-01

    The purpose of this study was to develop and validate a liquid chromatography-tandem mass spectrometry method for the identification and quantification of anticoagulant (anti-vitamin K or AVK) compounds, including rodenticides, drugs, and natural products because no published method could be found. The proposed method is based on ion-trap technology with electrospray ionization (ESI) and multiple reaction monitoring (MRM) technique. Each AVK is identified by means of its retention time, precursor ion, and two product ions. Plasma samples are extracted by liquid-liquid partition on Toxi-tube B((R)). The method was validated on dog plasma and gave good results in terms of specificity, linearity, and percent recovery for the 14 AVK tested (warfarin, acenocoumarol, bromadiolone, brodifacoum, chlorophacinone, coumatetralyl, dicoumarol, difenacoum, difethialone, flocoumafen, fluindione, phenindione, and tioclomarol). The limits of detection ranged from 5 to 25 ng/mL. Intraday repeatability was good, but interday repeatability was more variable though still sufficient for our diagnostic purposes. The technique was successfully applied in a series of clinical investigations to demonstrate its applicability in various animal species and gave very high sensitivity and specificity results. PMID:20223102

  20. Validation of a new liquid chromatography- tandem mass spectrometry ion-trap technique for the simultaneous determination of thirteen anticoagulant rodenticides, drugs, or natural products.

    PubMed

    Fourel, Isabelle; Hugnet, Christophe; Goy-Thollot, Isabelle; Berny, Philippe

    2010-03-01

    The purpose of this study was to develop and validate a liquid chromatography-tandem mass spectrometry method for the identification and quantification of anticoagulant (anti-vitamin K or AVK) compounds, including rodenticides, drugs, and natural products because no published method could be found. The proposed method is based on ion-trap technology with electrospray ionization (ESI) and multiple reaction monitoring (MRM) technique. Each AVK is identified by means of its retention time, precursor ion, and two product ions. Plasma samples are extracted by liquid-liquid partition on Toxi-tube B((R)). The method was validated on dog plasma and gave good results in terms of specificity, linearity, and percent recovery for the 14 AVK tested (warfarin, acenocoumarol, bromadiolone, brodifacoum, chlorophacinone, coumatetralyl, dicoumarol, difenacoum, difethialone, flocoumafen, fluindione, phenindione, and tioclomarol). The limits of detection ranged from 5 to 25 ng/mL. Intraday repeatability was good, but interday repeatability was more variable though still sufficient for our diagnostic purposes. The technique was successfully applied in a series of clinical investigations to demonstrate its applicability in various animal species and gave very high sensitivity and specificity results.

  1. Fast, comprehensive two-dimensional liquid chromatography

    PubMed Central

    Stoll, Dwight R.; Li, Xiaoping; Wang, Xiaoli; Carr, Peter W.; Porter, Sarah E. G.; Rutan, Sarah C.

    2011-01-01

    The absolute need to improve the separating power of liquid chromatography, especially for multi-constituent biological samples, is becoming increasingly evident. In response, over the past few years, there has been a great deal of interest in the development of two dimension liquid chromatography (2DLC). Just as 1DLC is preferred to 1DGC based on its compatibility with biological materials we believe that ultimately 2DLC will be preferred to the much more highly developed 2DGC for such samples. The huge advantage of 2D chromatographic techniques over 1D methods is inherent in the tremendous potential increase in peak capacity (resolving power). This is especially true of comprehensive 2D chromatography wherein it is possible, under ideal conditions, to obtain a total peak capacity equal to the product of the peak capacities of the first and second dimension separations. However, the very long timescale (typically several hours to tens of hours) of comprehensive 2DLC is clearly its chief drawback. Recent advances in the use of higher temperatures to speed up isocratic and gradient elution liquid chromatography have been used to decrease the time needed to do the second dimension LC separation of 2DLC to about 20 seconds for a full gradient elution run. Thus fast, high temperature LC is becoming a very promising technique. Peak capacities of over 2000 and rates of peak capacity production of nearly 1 peak/s have been achieved. In consequence, many real samples showing more than 200 peaks with signal to noise ratios of better than 10:1 have been run in total times of under 30 minutes. This report is not intended to be a comprehensive review of 2DLC, but is deliberately focused on the issues involved in doing fast 2DLC by means of elevating the column temperature; however, many issues of broader applicability will be discussed. PMID:17888443

  2. High perfomance liquid chromatography in pharmaceutical analyses.

    PubMed

    Nikolin, Branko; Imamović, Belma; Medanhodzić-Vuk, Saira; Sober, Miroslav

    2004-05-01

    compounds often present in concentrations much greater than those of analyte. Analiyte concentrations are often low, and in the case of drugs, the endogenous compounds are sometimes structurally very similar to the drug to be measured. The binding of drugs to the plasma protein also may occur which decreases the amount of free compound that is measured. To undertake the analyses of drugs and metabolites in body fluids the analyst is facet with several problems. The first problem is due to the complex nature of the body fluid, the drugs must be isolated by an extraction technique, which ideally should provide a relatively clean extract, and the separation system must be capable of resolving the drugs of interest from co extractives. All mentioned when we are using high performance liquid chromatography require good selections of detectors, good stationary phase, eluents and adequate program during separation. UV/VIS detector is the most versatile detector used in high performance liquid chromatography it is not always ideal since it is lack of specificity means high resolution of the analyte that may be required. UV detection is preferred since it offers excellent linearity and rapid quantitative analyses can be performed against a single standard of the drug being determined. Diode array and rapid scanning detector are useful for peak identification and monitoring peak purity but they are somewhat less sensitive then single wavelength detectors. In liquid chromatography some components may have a poor UV chromophores if UV detection is being used or be completely retained on the liquid chromatography column. Fluorescence and electrochemical detector are not only considerably more sensitive towed appropriate analytes but also more selective than UV detectors for many compounds. If at all possible fluorescence detectors are sensitive, stable, selective and easy to operate. It is selectivity shows itself in the lack of frontal components observed in plasma extract whereas

  3. Comprehensive metabolite profiling of Plantaginis Semen using ultra high performance liquid chromatography with electrospray ionization quadrupole time-of-flight tandem mass spectrometry coupled with elevated energy technique.

    PubMed

    Wang, Dandan; Qi, Meng; Yang, Qiming; Tong, Renchao; Wang, Rui; Bligh, S W Annie; Yang, Li; Wang, Zhengtao

    2016-05-01

    Plantaginis Semen is commonly used in traditional medicine to treat edema, hypertension, and diabetes. The commercially available Plantaginis Semen in China mainly comes from three species. To clarify the chemical composition and distinct different species of Plantaginis Semen, we established a metabolite profiling method based on ultra high performance liquid chromatography with electrospray ionization quadrupole time-of-flight tandem mass spectrometry coupled with elevated energy technique. A total of 108 compounds, including phenylethanoid glycosides, flavonoids, guanidine derivatives, terpenoids, organic acids, and fatty acids, were identified from Plantago asiatica L., P. depressa Willd., and P. major L. Results showed significant differences in chemical components among the three species, particularly flavonoids. This study is the first to provide a comprehensive chemical profile of Plantaginis Semen, which could be involved into the quality control, medication guide, and developing new drug of Plantago seeds.

  4. Comprehensive metabolite profiling of Plantaginis Semen using ultra high performance liquid chromatography with electrospray ionization quadrupole time-of-flight tandem mass spectrometry coupled with elevated energy technique.

    PubMed

    Wang, Dandan; Qi, Meng; Yang, Qiming; Tong, Renchao; Wang, Rui; Bligh, S W Annie; Yang, Li; Wang, Zhengtao

    2016-05-01

    Plantaginis Semen is commonly used in traditional medicine to treat edema, hypertension, and diabetes. The commercially available Plantaginis Semen in China mainly comes from three species. To clarify the chemical composition and distinct different species of Plantaginis Semen, we established a metabolite profiling method based on ultra high performance liquid chromatography with electrospray ionization quadrupole time-of-flight tandem mass spectrometry coupled with elevated energy technique. A total of 108 compounds, including phenylethanoid glycosides, flavonoids, guanidine derivatives, terpenoids, organic acids, and fatty acids, were identified from Plantago asiatica L., P. depressa Willd., and P. major L. Results showed significant differences in chemical components among the three species, particularly flavonoids. This study is the first to provide a comprehensive chemical profile of Plantaginis Semen, which could be involved into the quality control, medication guide, and developing new drug of Plantago seeds. PMID:27030316

  5. Liquid phase chromatography on microchips.

    PubMed

    Kutter, Jörg P

    2012-01-20

    Over the past twenty years, the field of microfluidics has emerged providing one of the main enabling technologies to realize miniaturized chemical analysis systems, often referred to as micro-Total Analysis Systems (uTAS), or, more generally, Lab-on-a-Chip Systems (LOC) [1,2]. While microfluidics was driven forward a lot from the engineering side, especially with respect to ink jet and dispensing technology, the initial push and interest from the analytical chemistry community was through the desire to develop miniaturized sensors, detectors, and, very early on, separation systems. The initial almost explosive development of, in particular, chromatographic separation systems on microchips, has, however, slowed down in recent years. This review takes a closer, critical look at how liquid phase chromatography has been implemented in miniaturized formats over the past several years, what is important to keep in mind when developing or working with separations in a miniaturized format, and what challenges and pitfalls remain.

  6. Direct determination of theophylline in human serum by high-performance liquid chromatography using zwitterionic micellar mobile phase. Comparison with an enzyme multiplied immunoassay technique.

    PubMed

    Habel, D; Guermouche, S; Guermouche, M H

    1993-12-01

    A liquid chromatographic procedure is reported for the direct determination of theophylline in human serum. It includes the use of a micellar zwitterionic mobile phase [10(-3) mol l-1 3-(dimethyldodecylammonio) propanesulfonate (also known as C12 DAPS)-propanol (97 + 3, v/v) and a muBondapak phenyl column. Detection is based on ultraviolet absorption at a wavelength of 273 nm. After dilution with the mobile phase, the serum is injected into the chromatography; no solvent extraction or deproteinization is performed. The linearity of the method described was excellent over the range 0.5-20 mg l-1. The within-run precision was better than 2%, and the recovery of the theophylline approached 98%. Two hundred direct injections of serum samples did not affect the column life. The total analysis time, including chromatography, was approximately 15 min. As little as 0.5 mg l-1 of theophylline could be detected, and the results were in good agreement with those of an enzyme multiplied immunoassay technique.

  7. High-Performance Liquid Chromatography-Mass Spectrometry.

    ERIC Educational Resources Information Center

    Vestal, Marvin L.

    1984-01-01

    Reviews techniques for online coupling of high-performance liquid chromatography with mass spectrometry, emphasizing those suitable for application to nonvolatile samples. Also summarizes the present status, strengths, and weaknesses of various techniques and discusses potential applications of recently developed techniques for combined liquid…

  8. Multi-dimensional Liquid Chromatography in Proteomics

    PubMed Central

    Zhang, Xiang; Fang, Aiqin; Riley, Catherine P.; Wang, Mu; Regnier, Fred E.; Buck, Charles

    2010-01-01

    Proteomics is the large-scale study of proteins, particularly their expression, structures and functions. This still-emerging combination of technologies aims to describe and characterize all expressed proteins in a biological system. Because of upper limits on mass detection of mass spectrometers, proteins are usually digested into peptides and the peptides are then separated, identified and quantified from this complex enzymatic digest. The problem in digesting proteins first and then analyzing the peptide cleavage fragments by mass spectrometry is that huge numbers of peptides are generated that overwhelm direct mass spectral analyses. The objective in the liquid chromatography approach to proteomics is to fractionate peptide mixtures to enable and maximize identification and quantification of the component peptides by mass spectrometry. This review will focus on existing multidimensional liquid chromatographic (MDLC) platforms developed for proteomics and their application in combination with other techniques such as stable isotope labeling. We also provide some perspectives on likely future developments. PMID:20363391

  9. Extraction of three bioactive diterpenoids from Andrographis paniculata: effect of the extraction techniques on extract composition and quantification of three andrographolides using high-performance liquid chromatography.

    PubMed

    Kumar, Satyanshu; Dhanani, Tushar; Shah, Sonal

    2014-10-01

    Andrographis paniculata (Burm.f.) wall.ex Nees (Acanthaceae) or Kalmegh is an important medicinal plant finding uses in many Ayurvedic formulations. Diterpenoid compounds andrographolides (APs) are the main bioactive phytochemicals present in leaves and herbage of A. paniculata. The efficiency of supercritical fluid extraction (SFE) using carbon dioxide was compared with the solid-liquid extraction techniques such as solvent extraction, ultrasound-assisted solvent extraction and microwave-assisted solvent extraction with methanol, water and methanol-water as solvents. Also a rapid and validated reverse-phase high-performance liquid chromatography-diode array detection method was developed for the simultaneous determination of the three biologically active compounds, AP, neoandrographolide and andrograpanin, in the extracts of A. paniculata. Under the best SFE conditions tested for diterpenoids, which involved extraction at 60°C and 100 bar, the extractive efficiencies were 132 and 22 µg/g for AP and neoandrographolide, respectively. The modifier percentage significantly affected the extraction efficiency.

  10. Analysis of quinolone antibiotic derivatives in sewage sludge samples by liquid chromatography-tandem mass spectrometry: comparison of the efficiency of three extraction techniques.

    PubMed

    Dorival-García, N; Zafra-Gómez, A; Camino-Sánchez, F J; Navalón, A; Vílchez, J L

    2013-03-15

    This work presents a comparison of three extraction techniques -ultrasound-assisted extraction (USE), microwave-assisted extraction (MAE) and pressurized liquid extraction (PLE) - and evaluates their efficiency in the determination of quinolone antibiotics in sewage sludge samples. Extraction parameters for each technique were optimized using design of experiments, and the compounds were detected and quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS), operating in positive electrospray ionization (ESI) mode. The use of two selected reaction monitoring transitions for each compound allowed simultaneous quantification and identification in one run. Analytes were separated in less than 10 min. Marbofloxacin and cincophen were used as surrogates for amphoteric and acid quinolones, respectively. The limits of detection (LODs) were between 2 and 5 ng g(-1), and the limits of quantification (LOQs) were between 4 and 18 ng g(-1) for the various analytes. The inter- and intra-day variability was <7%. Due to the absence of certified reference materials (CRMs), the method was validated using matrix-matched calibration and a recovery assay with spiked samples. Recovery rates were between 97.9% and 104.8%. Statistical comparison demonstrated no significant differences between the three extraction techniques. The methods were successfully applied for the determination of quinolones in sewage sludge samples collected from different wastewater treatments plants (WWTPs) located in the province of Granada (Spain). The analytical methods developed here may be useful for the development of more in-depth studies on the occurrence and fate of these commonly used pharmaceuticals in WWTPs and in the environment. PMID:23598102

  11. [High-performance liquid-liquid chromatography in beverage analysis].

    PubMed

    Bricout, J; Koziet, Y; de Carpentrie, B

    1978-01-01

    Liquid liquid chromatography was performed with columns packed with stationary phases chemically bonded to silica microparticules. These columns show a high efficiency and are used very easily. Flavouring compounds like aromatic aldehydes which have a low volatility were analyzed in brandy using a polar phase alkylnitrile. Sapid substances like amarogentin in Gentiana lutea or glyryrrhizin in Glycyrrhiza glabra were determined by reversed phase chromatography. Finally ionizable substances like synthetic dyes can be analyzed by paired ion chromatography witha non polar stationary phase.

  12. [Online enrichment ability of restricted-access column coupled with high performance liquid chromatography by column switching technique for benazepril hydrochloride].

    PubMed

    Zhang, Xiaohui; Wang, Rong; Xie, Hua; Yin, Qiang; Li, Xiaoyun; Jia, Zhengping; Wu, Xiaoyu; Zhang, Juanhong; Li, Wenbin

    2013-05-01

    The online enrichment ability of the restricted-access media (RAM) column coupled with high performance liquid chromatography by column switching technique for benazepril hydrochloride in plasma was studied. The RAM-HPLC system consisted of an RAM column as enrichment column and a C18 column as analytical column coupled via the column switching technique. The effects of the injection volume on the peak area and the systematic pressure were studied. When the injection volume was less than 100 microL, the peak area increased with the increase of the injection volume. However, when the injection volume was more than 80 microL, the pressure of whole system increased obviously. In order to protect the whole system, 80 microL was chosen as the maximum injection volume. The peak areas of ordinary injection and the large volume injection showed a good linear relationship. The enrichment ability of RAM-HPLC system was satisfactory. The system was successfully used for the separation and detection of the trace benazepril hydrochloride in rat plasma after its administration. The sensitivity of HPLC can be improved by RAM pre-enrichment. It is a simple and economic measurement method.

  13. Secondary metabolites isolation in natural products chemistry: comparison of two semipreparative chromatographic techniques (high pressure liquid chromatography and high performance thin-layer chromatography).

    PubMed

    Do, Thi Kieu Tiên; Hadji-Minaglou, Francis; Antoniotti, Sylvain; Fernandez, Xavier

    2014-01-17

    Chemical investigations on secondary metabolites in natural products chemistry require efficient isolation techniques for characterization purpose as well as for the evaluation of their biological properties. In the case of phytochemical studies, the performance of the techniques is critical (resolution and yield) since the products generally present a narrow range of polarity and physicochemical properties. Several techniques are currently available, but HPLC (preparative and semipreparative) is the most widely used. To compare the performance of semipreparative HPLC and HPTLC for the isolation of secondary metabolites in different types of extracts, we have chosen carvone from spearmint essential oil (Mentha spicata L.), resveratrol from Fallopia multiflora (Thunb.) Haraldson, and rosmarinic acid from rosemary (Rosmarinus officinalis L.) extracts. The comparison was based on the chromatographic separation, the purity and quantity of isolated compounds, the solvent consumption, the duration and the cost of the isolation operations. The results showed that semipreparative HPTLC can in some case offer some advantages over conventional semipreparative HPLC.

  14. A novel fatty-acid-based in-tube dispersive liquid-liquid microextraction technique for the rapid determination of nonylphenol and 4-tert-octylphenol in aqueous samples using high-performance liquid chromatography-ultraviolet detection.

    PubMed

    Shih, Hou-Kuang; Shu, Ting-Yun; Ponnusamy, Vinoth Kumar; Jen, Jen-Fon

    2015-01-01

    In this study, a novel fatty-acid-based in-tube dispersive liquid-liquid microextraction (FA-IT-DLLME) technique is proposed for the first time and is developed as a simple, rapid and eco-friendly sample extraction method for the determination of alkylphenols in aqueous samples using high-performance liquid chromatography-ultraviolet detection (HPLC-UV). In this extraction method, medium-chain saturated fatty acids were investigated as a pH-dependent phase because they acted as either anionic surfactants or neutral extraction solvents based on the acid-base reaction caused solely by the adjustment of the pH of the solution. A specially designed home-made glass extraction tube with a built-in scaled capillary tube was utilized as the phase-separation device for the FA-IT-DLLME to collect and measure the separated extractant phase for analysis. Nonylphenol (NP) and 4-tert-octylphenol (4-tOP) were chosen as model analytes. The parameters influencing the FA-IT-DLLME were thoroughly investigated and optimized. Under the optimal conditions, the detector responses of NP and 4-tOP were linear in the concentration ranges of 5-4000 μg L(-1), with correlation coefficients of 0.9990 and 0.9996 for NP and 4-tOP, respectively. The limits of detection based on a signal-to-noise ratio of 3 were 0.7 and 0.5 μg L(-1), and the enrichment factors were 195 and 143 for NP and 4-tOP, respectively. The applicability of the developed method was demonstrated for the analysis of alkylphenols in environmental wastewater samples, and the recoveries ranged from 92.9 to 107.1%. The extraction process required less than 4 min and utilized only acids, alkalis, and fatty acids to achieve the extraction. The results demonstrated that the presented FA-IT-DLLME approach is highly cost-effective, simple, rapid and environmentally friendly in its sample preparation.

  15. Determination of mercury species by the diffusive gradient in thin film technique and liquid chromatography--atomic fluorescence spectrometry after microwave extraction.

    PubMed

    Pelcová, Pavlína; Dočekalová, Hana; Kleckerová, Andrea

    2015-03-25

    A diffusive gradient in thin films technique (DGT) was combined with liquid chromatography (LC) and cold vapor atomic fluorescence spectrometry (CV-AFS) for the simultaneous quantification of four mercury species (Hg(2+), CH3Hg(+), C2H5Hg(+), and C6H5Hg(+)). After diffusion through an agarose diffusive layer, the mercury species were accumulated in resin gels containing thiol-functionalized ion-exchange resins (Duolite GT73, and Ambersep GT74). A microwave-assisted extraction (MAE) in the presence of 6M HCl and 5 M HCl (55 °C, 15 min) was used for isolation of mercury species from Ambersep and Duolite resin gels, respectively. The extraction efficiency was higher than 95.0% (RSD 3.5%). The mercury species were separated with a mobile phase containing 6.2% methanol+0.05% 2-mercaptoethanol+0.02 M ammonium acetate with a stepwise increase of methanol content up to 80% in the 16th min on a Zorbax C18 reverse phase column. The LODs of DGT-MAE-LC-CV-AFS method were 38 ng L(-1) for CH3Hg(+), 13 ng L(-1) for Hg(2+), 34 ng L(-1) for C2H5Hg(+) and 30 ng L(-1) for C6H5Hg(+) for 24 h DGT accumulation at 25 °C.

  16. Analysis of buprenorphine in rat plasma using a solid-phase extraction technique and high-performance liquid chromatography with electrochemical detection.

    PubMed

    Salem, A; Pierce, T L; Hope, W

    1997-03-01

    A solid-phase extraction method and sensitive reversed phase high-performance liquid chromatography analysis with electrochemical detection of buprenorphine and its metabolite, norbuprenorphine, in rat plasma is described. Adequate separation of the compounds of interest was achieved on a Phenomenex C18 reversed-phase column using a mobile phase comprising phosphate buffer: acetonitrile (75:25, pH 3.0) and 0.25 mM 1-octane-sulfonic acid, at a flow rat of 1 ml/min. Electrochemical detection was performed at a potential of 0.75 V and sensitivity of 2 nA. Buprenorphine and norbuprenorphine were extracted from plasma by solid-phase extraction technique using naltrindole as an internal standard (IS). Recoveries of buprenorphine and norbuprenorphine following the extraction method were high (70%-89%) over the concentration range used (25-100 ng/ml) and no endogenous substances in plasma interfered with any of the sample components. The retention times for norbuprenorphine, IS, and buprenorphine were 8, 12.5, and 30.5 min, respectively. The limits of detection of buprenorphine and norbuprenorphine in spiked plasma samples were 25 and 5 ng/ml, respectively. Using this method, buprenorphine was detected in rat plasma in animals acutely treated with the drug (5 mg/kg, s.c.).

  17. Development of online sampling and matrix reduction technique coupled liquid chromatography/ion trap mass spectrometry for determination maduramicin in chicken meat.

    PubMed

    Chang, Kai Chun; Su, Jung Jeng; Cheng, Cheanyeh

    2013-11-15

    An online sampling and matrix reduction technique coupled liquid chromatography electrospray-ion-trap mass spectrometry was developed for rapid analysis of maduramicin (MAD) residue in chicken meat. Multiple-reaction monitoring of mass spectrometry in positive ion mode was used to detect maduramicin. A post-column continuous infusion of internal standard (nigericin) with matrix-matched calibration method was utilised for quantification. The linear concentration range of the calibration curve was 0-10.0 ng mL(-1) (r(2)=0.999). The limit of detection (quantification) was 0.08 ng g(-1) (0.28 ng g(-1)). The analytical accuracy of chicken meat samples for four spiked MAD concentrations (0.5, 1.0, 5.0, and 10.0 ng g(-1)) was 84-97% and their corresponding intra-day and inter-day precisions were 3.7-5.0% and 5.8-7.9%, respectively. The analysis time for one sample was 10 min. The application of the method for incurred chicken samples elucidates that MAD residue in chicken meat decreases during the withdrawal period.

  18. On-line solid phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry as a powerful technique for the determination of sulfonamide residues in soils.

    PubMed

    Tetzner, Natália Fernanda; Maniero, Milena Guedes; Rodrigues-Silva, Caio; Rath, Susanne

    2016-06-24

    Sulfonamides are antimicrobials used widely as veterinary drugs, and their residues have been detected in environmental matrices. An analytical method for determining sulfadiazine, sulfathiazole, sulfamethazine, sulfamethoxazole, sulfadimethoxine and sulfaquinoxaline residues in soils employing a solid phase extraction on-line technique coupled with ultra-high performance liquid chromatography and tandem mass spectrometry (SPE-UHPLC-MS/MS) was developed and validated in this study. SPE and chromatographic separation were performed using an Oasis HLB column and an Acquity UPLC BEH C18 analytical column, respectively, at 40°C. Samples were prepared by extracting sulfonamides from soil using a solid-liquid extraction method with water:acetonitrile, 1:1v/v (recovery of 70.2-99.9%). The following parameters were evaluated to optimize the on-line SPE process: sorbent type (Oasis and C8), sample volume (100-400μL), loading solvent (water and different proportions of water:methanol) and washing volume (0.19-0.66mL). The method produced linear results for all sulfonamides from 0.5 to 12.5ngg(-1) with a linearity greater than 0.99. The precision of the method was less than 15%, and the matrix effect was -27% to -87%. The accuracy was in the range of 77-112% for all sulfonamides. The limit of quantitation in the two soils (clay and sand) was 0.5ngg(-1). The SPE column allowed for the analysis of many (more than 2000) samples without decreasing the efficiency. PMID:27234844

  19. Liquid chromatography detection unit, system, and method

    SciTech Connect

    Derenzo, Stephen E.; Moses, William W.

    2015-10-27

    An embodiment of a liquid chromatography detection unit includes a fluid channel and a radiation detector. The radiation detector is operable to image a distribution of a radiolabeled compound as the distribution travels along the fluid channel. An embodiment of a liquid chromatography system includes an injector, a separation column, and a radiation detector. The injector is operable to inject a sample that includes a radiolabeled compound into a solvent stream. The position sensitive radiation detector is operable to image a distribution of the radiolabeled compound as the distribution travels along a fluid channel. An embodiment of a method of liquid chromatography includes injecting a sample that comprises radiolabeled compounds into a solvent. The radiolabeled compounds are then separated. A position sensitive radiation detector is employed to image distributions of the radiolabeled compounds as the radiolabeled compounds travel along a fluid channel.

  20. Determination of Sulfonamide Residues in Food by Micellar Liquid Chromatography

    PubMed Central

    Szymański, Arkadiusz

    2008-01-01

    This paper presents new methods of determination of sulfonamide residues in food products of animal origin, based on liquid chromatography with a micellar mobile phase. The methods employ a technique of direct injection of the sample and preliminary isolation of the analyte by extraction in the liquid-solid and liquid-liquid system. The methods have been characterized by providing the parameters of the calibration curves, the range of linearity, limit of detection, and precision and accuracy of particular determinations. The recovery of the sulfonamides introduced into the food products studied has also been determined. PMID:19696937

  1. A fast and innovative microextraction technique, μSPEed, followed by ultrahigh performance liquid chromatography for the analysis of phenolic compounds in teas.

    PubMed

    Porto-Figueira, Priscilla; Figueira, José A; Pereira, Jorge A M; Câmara, José S

    2015-12-11

    The objective of this study was to evaluate the efficiency of a promising solid phase microextraction technique, μSPEed, in the analysis of selected phenolic compounds from teas by ultrahigh performance liquid chromatography with photodiode array detection (μSPEed/UHPLC-PDA). The innovative μSPEed configuration uses 3-μm sorbent particles tightly packed in a disposable needle equipped with a pressure-driven valve to withdraw samples in a single direction. The system was operated by the electronic pipette eVol® and different parameters influencing the extraction efficiency, as the nature of sorbent, pH, loading and elution conditions, and solvents were optimized. The best extracting conditions were obtained by loading twice 100μL of tea samples through the PS/DVB-RP sorbent and eluting with 50μL of acidified MeOH 95%. The following chromatographic separation was carried out in an Acquity C18 BEH capillary column using a gradient of 0.1% FA and acetonitrile. The optimized μSPEed/UHPLC-PDA methodology is selective and specific and was properly validated for 8 phenolic compounds widely reported in different teas. Overall, an excellent analytical performance was obtained in the 0.2-20μg/L linear dynamic range (LDR), with very low limits of detection (LODs) and quantification (LOQs), ranging between 3.5-16.8ng/mL and 10.6-50.6ng/mL, respectively, high recoveries (89.3-103.3%), good precision (RSD<5%) and negligible matrix effect. The methodology was used to assess the target polyphenols concentration in several tea samples. Rutin and quercetin-3-glucoside were the most abundant phenolics in all tea samples analysed and, with exception of naringenin and cinnamic acid, which are present in high amounts in the investigated citric teas, remain phenolic compounds are present in trace levels.

  2. A fast and innovative microextraction technique, μSPEed, followed by ultrahigh performance liquid chromatography for the analysis of phenolic compounds in teas.

    PubMed

    Porto-Figueira, Priscilla; Figueira, José A; Pereira, Jorge A M; Câmara, José S

    2015-12-11

    The objective of this study was to evaluate the efficiency of a promising solid phase microextraction technique, μSPEed, in the analysis of selected phenolic compounds from teas by ultrahigh performance liquid chromatography with photodiode array detection (μSPEed/UHPLC-PDA). The innovative μSPEed configuration uses 3-μm sorbent particles tightly packed in a disposable needle equipped with a pressure-driven valve to withdraw samples in a single direction. The system was operated by the electronic pipette eVol® and different parameters influencing the extraction efficiency, as the nature of sorbent, pH, loading and elution conditions, and solvents were optimized. The best extracting conditions were obtained by loading twice 100μL of tea samples through the PS/DVB-RP sorbent and eluting with 50μL of acidified MeOH 95%. The following chromatographic separation was carried out in an Acquity C18 BEH capillary column using a gradient of 0.1% FA and acetonitrile. The optimized μSPEed/UHPLC-PDA methodology is selective and specific and was properly validated for 8 phenolic compounds widely reported in different teas. Overall, an excellent analytical performance was obtained in the 0.2-20μg/L linear dynamic range (LDR), with very low limits of detection (LODs) and quantification (LOQs), ranging between 3.5-16.8ng/mL and 10.6-50.6ng/mL, respectively, high recoveries (89.3-103.3%), good precision (RSD<5%) and negligible matrix effect. The methodology was used to assess the target polyphenols concentration in several tea samples. Rutin and quercetin-3-glucoside were the most abundant phenolics in all tea samples analysed and, with exception of naringenin and cinnamic acid, which are present in high amounts in the investigated citric teas, remain phenolic compounds are present in trace levels. PMID:26585207

  3. Determination of coumarin anticoagulant rodenticide residues in animal tissue by high-performance liquid chromatography. I. Fluorescence detection using post-column techniques.

    PubMed

    Hunter, K

    1983-11-18

    A multi-residue method was developed for the determination of the rodenticides warfarin, coumatetralyl, bromadiolone, difenacoum and brodifacoum in animal tissues by high-performance liquid chromatography with fluorescence detection. Extracts were cleaned-up by gel permeation chromatography on Bio-Beads SX-3 and residues determined by normal and reversed-phase high-performance liquid chromatography using post-column pH-switching, with chloroform -sec.-butylamine and borate buffer (pH 10.4) respectively, to maximise the native fluorimetric responses. Confirmation of identification was possible by re-chromatographing extracts in the absence of the post-column reagent. Chloroform-acetone (1:1) was significantly better than chloroform for the extraction of residues of these rodenticides from liver tissues. Recoveries from spiked liver tissue were generally greater than 90% at levels of 0.05-1 mg kg-1. Detection limits in animal tissues of 0.002 mg kg-1 for coumatetratyl, difenacoum and brodifacoum, 0.01 mg kg-1 for bromadiolone and 0.02 mg kg-1 for warfarin and could be routinely achieved. PMID:6655019

  4. High-throughput method for macrolides and lincosamides antibiotics residues analysis in milk and muscle using a simple liquid-liquid extraction technique and liquid chromatography-electrospray-tandem mass spectrometry analysis (LC-MS/MS).

    PubMed

    Jank, Louise; Martins, Magda Targa; Arsand, Juliana Bazzan; Campos Motta, Tanara Magalhães; Hoff, Rodrigo Barcellos; Barreto, Fabiano; Pizzolato, Tânia Mara

    2015-11-01

    A fast and simple method for residue analysis of the antibiotics classes of macrolides (erythromycin, azithromycin, tylosin, tilmicosin and spiramycin) and lincosamides (lincomycin and clindamycin) was developed and validated for cattle, swine and chicken muscle and for bovine milk. Sample preparation consists in a liquid-liquid extraction (LLE) with acetonitrile, followed by liquid chromatography-electrospray-tandem mass spectrometry analysis (LC-ESI-MS/MS), without the need of any additional clean-up steps. Chromatographic separation was achieved using a C18 column and a mobile phase composed by acidified acetonitrile and water. The method was fully validated according the criteria of the Commission Decision 2002/657/EC. Validation parameters such as limit of detection, limit of quantification, linearity, accuracy, repeatability, specificity, reproducibility, decision limit (CCα) and detection capability (CCβ) were evaluated. All calculated values met the established criteria. Reproducibility values, expressed as coefficient of variation, were all lower than 19.1%. Recoveries range from 60% to 107%. Limits of detection were from 5 to 25 µg kg(-1).The present method is able to be applied in routine analysis, with adequate time of analysis, low cost and a simple sample preparation protocol.

  5. Elucidation of Flavonoids from Carissa congesta, Polyalthia longifolia, and Benincasa hispida Plant Extracts by Hyphenated Technique of Liquid Chromatography-mass Spectroscopy

    PubMed Central

    Doshi, Gaurav M.; Nalawade, Vivek V.; Mukadam, Aaditi S.; Chaskar, Pratip K.; Zine, Sandeep P.; Somani, Rakesh R.; Une, Hemant D.

    2016-01-01

    Background: Carissa congesta (CC), Polyalthia longifolia (PL), and Benincasa hispida (BH) are economically important plants. Objective: Current research encompasses identification of quercetin and rutin and their analogues by liquid chromatography-mass spectroscopy (LC-MS) from the selected plant species. Materials and Methods: Fresh roots, leaves, and seeds of CC, PL, and BH plants respectively were shade-dried followed by extraction and elucidation of rutin and quercetin by LC-MS. Results: Structural elucidation of CC, PL, and BH extracts revealed the presence of flavonoids such as quercetin (m/z 301) and rutin (m/z 610) as the parent ions along with presence of close analogues such as quercetin-O-hexoside, Vicenin 2, quercetin-3-O-xyloside/arabinoside, and quercetin-3-O-glucoside were identified as fragments. Conclusions: Thus, CC, PL, and BH extracts revealed the presence of flavonoids belonging to the class of flavonols such as rutin and quercetin. SUMMARY Quercetin and rutin were identified from CC roots, PL leaves and BH seeds by liquid chromatography-mass spectroscopy.Quercetin was characterized at (m/z 301) and rutin (m/z 610) as the parent ion peaks.Analogues such as quercetin-O-hexoside, Vicenin 2 and quercetin-3-O-glucoside were identified as fragments.

  6. Elucidation of Flavonoids from Carissa congesta, Polyalthia longifolia, and Benincasa hispida Plant Extracts by Hyphenated Technique of Liquid Chromatography-mass Spectroscopy

    PubMed Central

    Doshi, Gaurav M.; Nalawade, Vivek V.; Mukadam, Aaditi S.; Chaskar, Pratip K.; Zine, Sandeep P.; Somani, Rakesh R.; Une, Hemant D.

    2016-01-01

    Background: Carissa congesta (CC), Polyalthia longifolia (PL), and Benincasa hispida (BH) are economically important plants. Objective: Current research encompasses identification of quercetin and rutin and their analogues by liquid chromatography-mass spectroscopy (LC-MS) from the selected plant species. Materials and Methods: Fresh roots, leaves, and seeds of CC, PL, and BH plants respectively were shade-dried followed by extraction and elucidation of rutin and quercetin by LC-MS. Results: Structural elucidation of CC, PL, and BH extracts revealed the presence of flavonoids such as quercetin (m/z 301) and rutin (m/z 610) as the parent ions along with presence of close analogues such as quercetin-O-hexoside, Vicenin 2, quercetin-3-O-xyloside/arabinoside, and quercetin-3-O-glucoside were identified as fragments. Conclusions: Thus, CC, PL, and BH extracts revealed the presence of flavonoids belonging to the class of flavonols such as rutin and quercetin. SUMMARY Quercetin and rutin were identified from CC roots, PL leaves and BH seeds by liquid chromatography-mass spectroscopy.Quercetin was characterized at (m/z 301) and rutin (m/z 610) as the parent ion peaks.Analogues such as quercetin-O-hexoside, Vicenin 2 and quercetin-3-O-glucoside were identified as fragments. PMID:27695269

  7. Recent advances in ultra-high performance liquid chromatography for the analysis of traditional chinese medicine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Traditional Chinese medicines (TCMs) have been widely used for the prevention and treatment of various diseases for thousands of years in China. Ultra Performance Liquid Chromatography (UHPLC) is a relatively new technique offering new possibilities in liquid chromatography. This paper reviews recen...

  8. A robust micro-electrospray ionization technique for high-throughput liquid chromatography/mass spectrometry proteomics using a sanded metal needle as an emitter.

    PubMed

    Guzzetta, Andrew W; Thakur, Rohan A; Mylchreest, Iain C

    2002-01-01

    A 60 microm internal diameter (i.d.) stainless-steel needle was adapted to the orthogonal ESI probe ( microESI) of a commercial ion trap mass spectrometer, and used for capillary liquid chromatography/tandem mass spectrometry (LC/MS/MS) protein identification experiments. The modification allows for the use of nitrogen sheath gas which helps in the nebulization at LC flow rates exceeding 500 nL/min and eliminates problems caused by liquid junctions commonly used to initiate nanospray ionization (NSI). A comparison is made between the performance of a 75 microm i.d. column with a 15 microm pulled glass tip using a liquid junction, and that of a 150 microm i.d. column using the new microESI device. The combination of the 150 microm i.d. column and microESI gave sensitivity close to that of NSI (250 attomoles horse heart myoglobin digest on column), and proved to be more robust than the standard pulled glass tips of similar i.d. No evidence of metal needle catalyzed oxidation of methionine was observed during analysis of the tetrapeptide MRFA under a range of test conditions. Phosphorylated peptides in a beta-casein tryptic digest were also successfully identified using the microESI interface with a steel needle. In addition it was found that a mild sanding of the metal needle tip improved spray performance. PMID:12391582

  9. Solid-phase microextraction coupled with high performance liquid chromatography: a complementary technique to solid-phase microextraction-gas chromatography for the analysis of pesticide residues in strawberries.

    PubMed

    Wang, Z; Hennion, B; Urruty, L; Montury, M

    2000-11-01

    Solid-phase microextraction coupled with high performance liquid chromatography has been studied for the analysis of methiocarb, napropamide, fenoxycarb and bupirimate in strawberries. The strawberries were blended and centrifuged. Then, an aliquot of the resulting extracting solution was subjected to solid-phase microextraction (SPME) on a 60 microns polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre for 45 min at room temperature. The extracted pesticides on the SPME fibre were desorbed into SPME/high performance liquid chromatography (HPLC) interface for HPLC analysis with diode-array detection (DAD). The method is organic solvent-free for the whole extraction process and is simple and easy to manipulate. The detection limits were shown to be at low microgram kg-1 level and the linear response covered the range from 0.05 to 2 mg kg-1 of pesticides in strawberries with a regression coefficient larger than 0.99. A good repeatability with RSDs between 2.92 and 9.25% was obtained, depending on compounds.

  10. Solid-phase microextraction coupled with high performance liquid chromatography: a complementary technique to solid-phase microextraction-gas chromatography for the analysis of pesticide residues in strawberries.

    PubMed

    Wang, Z; Hennion, B; Urruty, L; Montury, M

    2000-11-01

    Solid-phase microextraction coupled with high performance liquid chromatography has been studied for the analysis of methiocarb, napropamide, fenoxycarb and bupirimate in strawberries. The strawberries were blended and centrifuged. Then, an aliquot of the resulting extracting solution was subjected to solid-phase microextraction (SPME) on a 60 microns polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre for 45 min at room temperature. The extracted pesticides on the SPME fibre were desorbed into SPME/high performance liquid chromatography (HPLC) interface for HPLC analysis with diode-array detection (DAD). The method is organic solvent-free for the whole extraction process and is simple and easy to manipulate. The detection limits were shown to be at low microgram kg-1 level and the linear response covered the range from 0.05 to 2 mg kg-1 of pesticides in strawberries with a regression coefficient larger than 0.99. A good repeatability with RSDs between 2.92 and 9.25% was obtained, depending on compounds. PMID:11271705

  11. Csaba Horvath and preparative liquid chromatography

    SciTech Connect

    Guiochon, Georges A

    2005-07-01

    Few chromatographers have been interested in furthering preparative liquid chromatography. The pioneers, Tswett, Kuhn and Lederer, A.J.P. Martin, Tiselius, isolated fractions but as an intermediate step in the analysis of their samples. The progress in electronics and sensors, and in their miniaturization has lead to the paradoxical situation that the analysts never see the transient pure fractions that their detector quantitates. Yet, over the last 25 years, preparative liquid chromatography has become an important industrial process for the separation, the extraction, and/or the purification of many pharmaceuticals or pharmaceutical intermediates, including pure enantiomers, purified peptides and proteins, compounds that are manufactured at the relatively large industrial scale of a few kilograms to several hundred tons per year. This development that has strongly affected the modern pharmaceutical industry is mainly due to the pioneering work of Csaba Horvath. His work in preparative HPLC was critical at both the practical and the theoretical levels. He was the first scientist in modern times to pay serious attention to the relationships between the curvature of the equilibrium isotherms, the competitive nature of nonlinear isotherms, and the chromatographic band profiles of complex mixtures. The thermodynamics of multi-component phase equilibria and mass transfer kinetics in chromatography attracted his interest and were the focus of ground-breaking contributions. He investigated displacement chromatography, an old method invented by Tiselius that Csaba was first to implement in HPLC. This choice was explained by the essential characteristic of displacement chromatography, in that it delivers fractions that can be far more concentrated than the feed. Remarkably, once the basics of nonlinear chromatography had been mastered in his group, most of the applications that were studied by his coworkers dealt with peptides of various sizes and with proteins. Thus, all

  12. A newcomer's guide to nano-liquid-chromatography of peptides.

    PubMed

    Fröhlich, Thomas; Arnold, Georg J

    2009-01-01

    LC-MS/MS is one of the most powerful techniques in the field of proteomics allowing high throughput identification of proteins out of complex protein mixtures. Besides high sample throughput, the analytical sensitivity is one of the major benefits of this technology. A prerequisite for sensitive LC-MS/MS approaches is chromatography with very low flow rates in the nanoliter per minute range, usually referred to as nano-liquid chromatography (nano-LC). However, to perform this separation technology, an appropriate instrumental setup as well experienced operators are a prerequisite. The aim of this chapter is to help nano-LC newcomers to get introduced to this fascinating technology. Technical components of nano-LC systems like solvent delivery systems, sample injection systems, and nano-chromatography columns are described. Detailed procedures to mount, test, and operate the system are outlined, and advices for an effective troubleshooting are provided.

  13. [Advances in multidimensional high performance liquid chromatography for separation technology in proteomic study].

    PubMed

    Gao, Mingxia; Guan, Xia; Hong, Guangfeng; Zhang, Xiangmin

    2009-09-01

    With the developments of proteomic study, multidimensional high performance liquid chromatography technology has attracted increasing interests due to its obvious advantages, such as rapid analysis, high automation and easy combination with mass spectrometry and so on. This review emphasizes the advances of multidimensional high performance liquid chromatography technology, including classical bottom-up methods, top-down techniques and array-based two-dimensional liquid chromatography system, which was designed and set up by our lab to improve the throughput. These techniques showed promising potential applications in proteomics study.

  14. Spillage detector for liquid chromatography systems

    NASA Technical Reports Server (NTRS)

    Jarvis, M. J.; Fulton, D. S. (Inventor)

    1986-01-01

    A spillage detector device for use in conjunction with fractionation of liquid chromatography systems which includes a spillage recieving enclosure beneath the fractionation area is described. A sensing device having a plurality of electrodes of alternating polarity is mounted within the spillage recieving enclosure. Detection circuitry, responsive to conductivity between electrodes, is operatively connected to the sensing device. The detection circuitry feeds into the output circuitry. The output circuit has relaying and switching circuitry directed to a solenoid, an alarm system and a pump. The solenoid is connected to the pliable conduit of the chromatography system. The alarm system comprises an audio alarm and a visual signal. A 115-volt power system interconnected with the pump, the solenoid, the sensing device, and the detection and output circuitry.

  15. Liquid chromatography and mass spectrometry in food allergen detection.

    PubMed

    Fæste, Christiane Kruse; Rønning, Helene Thorsen; Christians, Uwe; Granum, Per Einar

    2011-02-01

    Food allergy is an important issue in the field of food safety because of the hazards for affected persons and the hygiene requirements and legal regulations imposed on the food industry. Consumer protection and law enforcement require suitable analytical techniques for the detection of allergens in foods. Immunological methods are currently preferred; however, confirmatory alternatives are needed. The determination of allergenic proteins by liquid chromatography and mass spectrometry has greatly advanced in recent years, and gel-free allergenomics is becoming a routinely used approach for the identification and quantitation of food allergens. The present review provides a brief overview of the principles of proteomic procedures, various chromatographic set ups, and mass spectrometry instrumentation used in allergenomics. A compendium of published liquid chromatography methods, proteomic analyses, typical marker peptides, and quantitative assays for 14 main allergy-causing foods is also included.

  16. Tissue-specific metabolite profiling of Cyperus rotundus L. rhizomes and (+)-nootkatone quantitation by laser microdissection, ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry, and gas chromatography-mass spectrometry techniques.

    PubMed

    Jaiswal, Yogini; Liang, Zhitao; Guo, Ping; Ho, Hing-Man; Chen, Hubiao; Zhao, Zhongzhen

    2014-07-23

    Cyperus rotundus L. is a plant species commonly found in both India and China. The caused destruction of this plant is of critical concern for agricultural produce. Nevertheless, it can serve as a potential source of the commercially important sesquiterpenoid (+)-nootkatone. The present work describes comparative metabolite profiling and (+)-nootkatone content determination in rhizome samples collected from these two countries. Laser dissected tissues, namely, the cortex, hypodermal fiber bundles, endodermis, amphivasal vascular bundles, and whole rhizomes were analyzed by ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF MS). Gas chromatography-mass spectrometry (GC-MS) analysis was used for profiling of essential oil constituents and quantitation of (+)-nootkatone. The content of (+)-nootkatone was found to be higher in samples from India (30.47 μg/10 g) compared to samples from China (21.72 μg/10 g). The method was validated as per International Conference on Harmonisation (ICH) guidelines (Q2 R1). The results from this study can be applied for quality control and efficient utilization of this terpenoid-rich plant for several applications in food-based industries. PMID:24938835

  17. [Determination of estrogen residues in drinking water by on-line solid phase extraction based on sol-gel technique coupled with high performance liquid chromatography].

    PubMed

    Li, Longfei; Su, Min; Shi, Xiaolei; Wang, Yana; Wang, Minmin; He, Jinxing

    2014-02-01

    A method for the determination of diethylstilbestrol (DES), hexestrol (HEX) and dienestrol (DS) residues in drinking water was established by on-line solid phase extraction (SPE) coupled with high performance liquid chromatography (HPLC). The material synthesized on the base of sol-gel technology was employed as adsorbent. This material was prepared using 3-aminopropyltriethoxysilane (APTES) as the functional monomer, tetraethoxysilane (TEOS) as the crosslinking agent, and acetic acid as the initiator. The synthesized adsorbent showed outstanding property for the estrogen extraction. The estrogen can be caught effectively from water samples and the extraction can be achieved rapidly. Some important parameters, such as pH of sample solution, eluent solvents, loading flow rate, which might influence extraction efficiency, were optimized. The results indicated that the limit of detection (S/N = 3) of the developed method could reach 0.07-0.13 microg/L under the conditions of pH 7.0 of sample solution, methanol and 1% (v/v) acetic acid aqueous solution as the eluent solvent and the loading flow rate of 2 mL/min. The recoveries of the three estrogens from the water samples at three spiked levels ranged from 82.31% to 99.43% with RSD of 1.61%-7.15%. The method was simple, rapid, and suitable to detect the trace residues of estrogens in drinking water.

  18. Comparison of several extraction techniques for multiclass analysis of veterinary drugs in eggs using ultra-high pressure liquid chromatography-tandem mass spectrometry.

    PubMed

    Garrido Frenich, Antonia; Aguilera-Luiz, María del Mar; Martínez Vidal, Jose Luis; Romero-González, Roberto

    2010-02-28

    This study compared four extraction methods for the simultaneous determination of tetracyclines, macrolides, quinolones, sulphonamides and anthelmintics (including benzimidazoles and avermectins) in eggs by ultra-high pressure liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Solvent extraction, solid-phase extraction (SPE), matrix solid-phase dispersion (MSPD) and modified QuEChERS procedure were compared in terms of recovery and number of veterinary drugs extracted. The solvent extraction procedure with a clean-up step provided better results than the other tested procedures. The QuEChERS procedure was simpler and faster, but extracted fewer compounds than solvent extraction. MSPD did not extract tetracyclines and quinolones, whereas macrolides and tetracyclines were not extracted when SPE was applied. The solvent extraction procedure was validated, obtaining recoveries ranging from 60% (sulfaquinoxaline) to 119% (levamisole) with repeatability values (expressed as relative standard deviations, RSDs) lower than 20% at two concentration levels (10 and 100 microg kg(-1)), except for erythromycin, emamectin and ivermectin that showed RSD values close to 25% at 10 microg kg(-1). Limits of quantification (LOQs) were always equal or lower than 5 microg kg(-1). Finally the method was applied to egg samples, and erythromycin, enrofloxacin, difloxacin, thiabendazole, emamectin and fenbendazole were detected in four samples. PMID:20113729

  19. Metabolism, distribution, and excretion of deoxynivalenol with combined techniques of radiotracing, high-performance liquid chromatography ion trap time-of-flight mass spectrometry, and online radiometric detection.

    PubMed

    Wan, Dan; Huang, Lingli; Pan, Yuanhu; Wu, Qinghua; Chen, Dongmei; Tao, Yanfei; Wang, Xu; Liu, Zhenli; Li, Juan; Wang, Liye; Yuan, Zonghui

    2014-01-01

    Dispositions of deoxynivalenol (DON) in rats and chickens were investigated, using a radiotracer method coupled with a novel γ-accurate radioisotope counting (γ-ARC) radio-high-performance liquid chromatography ion trap time-of-flight tandem mass spectrometry (radio-HPLC-IT-TOF-MS/MS) system. 3β-(3)H-DON was chemically synthesized and orally administrated to both sexes of rats and chickens as single or multiple doses. The results showed that DON was widely distributed and quickly eliminated in all tissues. The highest concentration was found in the gastrointestinal tract at 6 h post-administration. Substantially lower levels were detected in the kidney, liver, heart, lung, spleen, and brain. Three new metabolites were identified tentatively as 10-deoxynivalenol-sulfonate, 10-deepoxy-deoxynivalenol (DOM-1)-sulfonate, and deoxynivalenol-3α-sulfate. Deoxynivalenol-3α-sulfate was a major metabolite in chickens, while the major forms in rats were DOM-1 and DON. Additionally, a higher excretion rate in urine was observed in female rats than in male rats. The differences in metabolite profiles and excretion rates, which suggested diverse ways to detoxify, may relate to the different tolerances in different genders or species.

  20. High-pressure liquid chromatography: A brief introduction and its application in analyzing the degradation of a C-ether (Thio-ether) liquid lubricant

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The general principles of classical liquid chromatography and high pressure liquid chromatography (HPLC) are reviewed, and their advantages and disadvantages are compared. Several chromatographic techniques are reviewed, and the analytical separation of a C-ether liquid lubricant by each technique is illustrated. A practical application of HPLC is then demonstrated by analyzing a degraded C-ether liquid lubricant from full scale, high temperature bearing tests.

  1. Determination of Phenolic Acids and Flavonoids in Taraxacum formosanum Kitam by Liquid Chromatography-Tandem Mass Spectrometry Coupled with a Post-Column Derivatization Technique

    PubMed Central

    Chen, Hung-Ju; Inbaraj, Baskaran Stephen; Chen, Bing-Huei

    2012-01-01

    A liquid chromatography-tandem mass spectrometry method (LC-MS/MS) was developed for the determination of phenolic acids and flavonoids in a medicinal Chinese herb Taraxacum formosanum Kitam. Initially, both phenolic acids and flavonoids were extracted with 50% ethanol in a water-bath at 60 °C for 3 h and eventually separated into acidic fraction and neutral fraction by using a C18 cartridge. A total of 29 compounds were separated within 68 min by employing a Gemini C18 column and a gradient solvent system of 0.1% formic acid and acetonitrile at a flow rate of 1.0 mL/min. Based on the retention behavior as well as absorption and mass spectra, 19 phenolic acids and 10 flavonoids were identified and quantified in T. formosanum, with the former ranging from 14.1 μg/g to 10,870.4 μg/g, and the latter from 9.9 μg/g to 325.8 μg/g. For further identification of flavonoids, a post-column derivatization method involving shift reagents such as sodium acetate or aluminum chloride was used and the absorption spectral characteristics without or with shift reagents were compared. An internal standard syringic acid was used for quantitation of phenolic acids, whereas (±) naringenin was found suitable for quantitation of flavonoids. The developed LC-MS/MS method showed high reproducibility, as evident from the relative standard deviation (RSD) values for intra-day and inter-day variability being 1.0–6.8% and 2.0–7.7% for phenolic acids and 3.7–7.4% and 1.5–8.1% for flavonoids, respectively, and thus may be applied for simultaneous determination of phenolic acids and flavonoids in Chinese herb and nutraceuticals. PMID:22312251

  2. Determination of phenolic acids and flavonoids in Taraxacum formosanum Kitam by liquid chromatography-tandem mass spectrometry coupled with a post-column derivatization technique.

    PubMed

    Chen, Hung-Ju; Inbaraj, Baskaran Stephen; Chen, Bing-Huei

    2012-01-01

    A liquid chromatography-tandem mass spectrometry method (LC-MS/MS) was developed for the determination of phenolic acids and flavonoids in a medicinal Chinese herb Taraxacum formosanum Kitam. Initially, both phenolic acids and flavonoids were extracted with 50% ethanol in a water-bath at 60 °C for 3 h and eventually separated into acidic fraction and neutral fraction by using a C(18) cartridge. A total of 29 compounds were separated within 68 min by employing a Gemini C(18) column and a gradient solvent system of 0.1% formic acid and acetonitrile at a flow rate of 1.0 mL/min. Based on the retention behavior as well as absorption and mass spectra, 19 phenolic acids and 10 flavonoids were identified and quantified in T. formosanum, with the former ranging from 14.1 μg/g to 10,870.4 μg/g, and the latter from 9.9 μg/g to 325.8 μg/g. For further identification of flavonoids, a post-column derivatization method involving shift reagents such as sodium acetate or aluminum chloride was used and the absorption spectral characteristics without or with shift reagents were compared. An internal standard syringic acid was used for quantitation of phenolic acids, whereas (±) naringenin was found suitable for quantitation of flavonoids. The developed LC-MS/MS method showed high reproducibility, as evident from the relative standard deviation (RSD) values for intra-day and inter-day variability being 1.0-6.8% and 2.0-7.7% for phenolic acids and 3.7-7.4% and 1.5-8.1% for flavonoids, respectively, and thus may be applied for simultaneous determination of phenolic acids and flavonoids in Chinese herb and nutraceuticals.

  3. Combination of multivariate curve resolution and multivariate classification techniques for comprehensive high-performance liquid chromatography-diode array absorbance detection fingerprints analysis of Salvia reuterana extracts.

    PubMed

    Hakimzadeh, Neda; Parastar, Hadi; Fattahi, Mohammad

    2014-01-24

    In this study, multivariate curve resolution (MCR) and multivariate classification methods are proposed to develop a new chemometric strategy for comprehensive analysis of high-performance liquid chromatography-diode array absorbance detection (HPLC-DAD) fingerprints of sixty Salvia reuterana samples from five different geographical regions. Different chromatographic problems occurred during HPLC-DAD analysis of S. reuterana samples, such as baseline/background contribution and noise, low signal-to-noise ratio (S/N), asymmetric peaks, elution time shifts, and peak overlap are handled using the proposed strategy. In this way, chromatographic fingerprints of sixty samples are properly segmented to ten common chromatographic regions using local rank analysis and then, the corresponding segments are column-wise augmented for subsequent MCR analysis. Extended multivariate curve resolution-alternating least squares (MCR-ALS) is used to obtain pure component profiles in each segment. In general, thirty-one chemical components were resolved using MCR-ALS in sixty S. reuterana samples and the lack of fit (LOF) values of MCR-ALS models were below 10.0% in all cases. Pure spectral profiles are considered for identification of chemical components by comparing their resolved spectra with the standard ones and twenty-four components out of thirty-one components were identified. Additionally, pure elution profiles are used to obtain relative concentrations of chemical components in different samples for multivariate classification analysis by principal component analysis (PCA) and k-nearest neighbors (kNN). Inspection of the PCA score plot (explaining 76.1% of variance accounted for three PCs) showed that S. reuterana samples belong to four clusters. The degree of class separation (DCS) which quantifies the distance separating clusters in relation to the scatter within each cluster is calculated for four clusters and it was in the range of 1.6-5.8. These results are then

  4. RNA footprinting analysis using ion pair reverse phase liquid chromatography.

    PubMed Central

    Dickman, Mark J; Conroy, Matthew J; Grasby, Jane A; Hornby, David P

    2002-01-01

    Hydroxyl radical footprinting is a powerful technique often employed in characterization of the tertiary interactions between proteins and nucleic acids. Following the generation of a nucleic acid "ladder" either by chemical or enzymatic reactions, the radiolabeled products are traditionally separated by denaturing gel electrophoresis and further quantified by phosphorimaging techniques. Here we report the use of ion pair reverse phase liquid chromatography to analyze the products of an RNA footprinting reaction using fluorescently labeled RNA molecules. This technique offers several advantages over existing procedures, including rapid analysis, automation, and direct quantification of the cleavage products without the need to employ radiolabeling. To illustrate the resolving power of this technique, we have analyzed the products of base hydrolysis, generated from a fluorescently labeled RNA molecule and have subsequently used this method to define the solvent accessibility of the substrate strand as it docks with the hairpin ribozyme. PMID:11911369

  5. Trends in High Performance Liquid Chromatography for Cultural Heritage.

    PubMed

    Degano, Ilaria; La Nasa, Jacopo

    2016-04-01

    The separation, detection and quantitation of specific species contained in a sample in the field of Cultural Heritage requires selective, sensitive and reliable methods. Procedures based on liquid chromatography fulfil these requirements and offer a wide range of applicability in terms of analyte types and concentration range. The main applications of High Performance Liquid Chromatography in this field are related to the separation and detection of dyestuffs in archaeological materials and paint samples by reversed-phase liquid chromatography with suitable detectors. The relevant literature will be revised, with particular attention to sample treatment strategies and future developments. Reversed phase chromatography has also recently gained increasing importance in the analysis of lipid binders and lipid materials in archaeological residues: the main advantages and disadvantages of the new approaches will be discussed. Finally, the main applications of ion chromatography and size exclusion chromatography in the field of Cultural Heritage will be revised in this chapter. PMID:27573145

  6. Trends in High Performance Liquid Chromatography for Cultural Heritage.

    PubMed

    Degano, Ilaria; La Nasa, Jacopo

    2016-04-01

    The separation, detection and quantitation of specific species contained in a sample in the field of Cultural Heritage requires selective, sensitive and reliable methods. Procedures based on liquid chromatography fulfil these requirements and offer a wide range of applicability in terms of analyte types and concentration range. The main applications of High Performance Liquid Chromatography in this field are related to the separation and detection of dyestuffs in archaeological materials and paint samples by reversed-phase liquid chromatography with suitable detectors. The relevant literature will be revised, with particular attention to sample treatment strategies and future developments. Reversed phase chromatography has also recently gained increasing importance in the analysis of lipid binders and lipid materials in archaeological residues: the main advantages and disadvantages of the new approaches will be discussed. Finally, the main applications of ion chromatography and size exclusion chromatography in the field of Cultural Heritage will be revised in this chapter.

  7. Nano-liquid chromatography in pharmaceutical and biomedical research.

    PubMed

    Gama, Mariana Roberto; Collins, Carol H; Bottoli, Carla B G

    2013-08-01

    Miniaturized separation techniques have emerged as environmentally friendly alternatives to available separation methods. Nano-liquid chromatography (nano-LC), microchip devices and nano-capillary electrophoresis are miniaturized methods that minimize reagent consumption and waste generation. Furthermore, the low levels of analytes, especially in biological samples, promote the search for more highly sensitive techniques; coupled to mass spectrometry, nano-LC has great potential to become an indispensable tool for routine analysis of biomolecules. This short review presents the fundamental aspects of nano-LC analytical instrumentation, discussing practical considerations and the primary differences between miniaturized and conventional instrumentation. Some theoretical aspects are discussed to better explain both the potential and the principal limitations of nano-LC. Recent pharmaceutical and biomedical applications of this separation technique are also presented to indicate the satisfactory performance for complex matrices, especially for proteomic analysis, that is obtained with nano-LC.

  8. Liquid Chromatography Applied to Space System

    NASA Astrophysics Data System (ADS)

    Poinot, Pauline; Chazalnoel, Pascale; Geffroy, Claude; Sternberg, Robert; Carbonnier, Benjamin

    Searching for signs of past or present life in our Solar System is a real challenge that stirs up the curiosity of scientists. Until now, in situ instrumentation was designed to detect and determine concentrations of a wide number of organic biomarkers. The relevant method which was and still is employed in missions dedicated to the quest of life (from Viking to ExoMars) corresponds to the pyrolysis-GC-MS. Along the missions, this approach has been significantly improved in terms of extraction efficiency and detection with the use of chemical derivative agents (e.g. MTBSTFA, DMF-DMA, TMAH…), and in terms of analysis sensitivity and resolution with the development of in situ high-resolution mass spectrometer (e.g. TOF-MS). Thanks to such an approach, organic compounds such as amino acids, sugars, tholins or polycyclic aromatic hydrocarbons (PAHs) were expected to be found. However, while there’s a consensus that the GC-MS of Viking, Huygens, MSL and MOMA space missions worked the way they had been designed to, pyrolysis is much more in debate (Glavin et al. 2001; Navarro-González et al. 2006). Indeed, (1) it is thought to remove low levels of organics, (2) water and CO2 could interfere with the detection of likely organic pyrolysis products, and (3) only low to mid-molecular weight organic molecules can be detected by this technique. As a result, researchers are now focusing on other in situ techniques which are no longer based on the volatility of the organic matter, but on the liquid phase extraction and analysis. In this line, micro-fluidic systems involving sandwich and/or competitive immunoassays (e.g. LMC, SOLID; Parro et al. 2005; Sims et al. 2012), micro-chip capillary electrophoreses (e.g. MOA; Bada et al. 2008), or nanopore-based analysis (e.g. BOLD; Schulze-Makuch et al. 2012) have been conceived for in situ analysis. Thanks to such approaches, molecular biological polymers (polysaccharides, polypeptides, polynucleotides, phospholipids, glycolipids

  9. Liquid Chromatography Applied to Space System

    NASA Astrophysics Data System (ADS)

    Poinot, Pauline; Chazalnoel, Pascale; Geffroy, Claude; Sternberg, Robert; Carbonnier, Benjamin

    Searching for signs of past or present life in our Solar System is a real challenge that stirs up the curiosity of scientists. Until now, in situ instrumentation was designed to detect and determine concentrations of a wide number of organic biomarkers. The relevant method which was and still is employed in missions dedicated to the quest of life (from Viking to ExoMars) corresponds to the pyrolysis-GC-MS. Along the missions, this approach has been significantly improved in terms of extraction efficiency and detection with the use of chemical derivative agents (e.g. MTBSTFA, DMF-DMA, TMAH…), and in terms of analysis sensitivity and resolution with the development of in situ high-resolution mass spectrometer (e.g. TOF-MS). Thanks to such an approach, organic compounds such as amino acids, sugars, tholins or polycyclic aromatic hydrocarbons (PAHs) were expected to be found. However, while there’s a consensus that the GC-MS of Viking, Huygens, MSL and MOMA space missions worked the way they had been designed to, pyrolysis is much more in debate (Glavin et al. 2001; Navarro-González et al. 2006). Indeed, (1) it is thought to remove low levels of organics, (2) water and CO2 could interfere with the detection of likely organic pyrolysis products, and (3) only low to mid-molecular weight organic molecules can be detected by this technique. As a result, researchers are now focusing on other in situ techniques which are no longer based on the volatility of the organic matter, but on the liquid phase extraction and analysis. In this line, micro-fluidic systems involving sandwich and/or competitive immunoassays (e.g. LMC, SOLID; Parro et al. 2005; Sims et al. 2012), micro-chip capillary electrophoreses (e.g. MOA; Bada et al. 2008), or nanopore-based analysis (e.g. BOLD; Schulze-Makuch et al. 2012) have been conceived for in situ analysis. Thanks to such approaches, molecular biological polymers (polysaccharides, polypeptides, polynucleotides, phospholipids, glycolipids

  10. Liquid chromatography/quadrupole time-of-flight mass spectrometry in combination with online hydrogen/deuterium exchange technique for structural elucidation of phase I metabolites of iso-phenylcyclopentylamine in rat bile.

    PubMed

    Liu, Xiaoxue; Wang, Suilou; Ding, Li; Chen, Xiaoping; Shen, Wenbin; Dong, Xin; Yun, Changhong; Lin, Hongda

    2014-10-01

    MS/MS experiment and accurate mass measurement are powerful tools in metabolite identification. However, sometimes these data do not provide enough information to assign an unambiguous structure to a metabolite. In combination with MS techniques, hydrogen/deuterium (H/D) exchange can provide additional information for structural elucidation by determination of the number of exchangeable hydrogen atoms in a structure. In this study, the principal phase I metabolites of iso-phenylcyclopentylamine in rat bile were identified by high-performance liquid chromatography with electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-Q-TOF-MS). Since N-oxidation may occur because of the existence of the primary amino group in the structure, it was difficult to differentiate the hydroxylated metabolites from N-oxides by ESI-Q-TOF-MS alone. Therefore, online H/D exchange technique was applied to solve this problem. Finally, 25 phase I metabolites were detected and structurally described, in which 11 were confirmed to be N-oxides. This study demonstrated the effectiveness of high-resolution mass spectrometry in combination with an online H/D exchange technique in rapid identification of drug metabolites, especially in discriminating hydroxylated metabolites from N-oxides.

  11. Ionic liquids as surfactants in micellar liquid chromatography.

    PubMed

    Flieger, Jolanta; Siwek, Agata; Pizoń, Magdalena; Czajkowska-Żelazko, Anna

    2013-05-01

    This paper is devoted to application of ionic liquids as surfactants in LC of organic compounds, derivatives of 1,4-thiosemicarbazides. According to HPLC requirements the most advantageous conditions such as transparency for ultraviolet light, low CMC, additional inorganic salt additives, and appropriate organic solvent were established. The CMC was determined using conductivity measurements. Suitability of two different stationary phases: RP-C18 and cyanopropyl bonded phase was examined under micellar conditions. Chosen ionic liquid surfactant was compared to common traditional amphiphilic reagent - SDS. Elaborated on chromatographic micellar conditions were tested as a pilot technique for prediction of distribution coefficients of organic analytes in ionic liquid-based aqueous two-phase system. PMID:23609988

  12. Chromatography

    MedlinePlus

    Chromatography is a way of separating two or more chemical compounds. Chemical compounds are chemicals that are ... of chemical compound. There are different kinds of chromatography. These include gas, high pressure liquid, or ion ...

  13. Structural analysis of amorphous phosphates using high performance liquid chromatography

    SciTech Connect

    Sales, B.C.; Boatner, L.A.; Chakoumakos, B.C.; McCallum, J.C.; Ramey, J.O.; Zuhr, R.A.

    1993-12-31

    Determining the atomic-scale structure of amorphous solids has proven to be a formidable scientific and technological problem for the past 100 years. The technique of high-performance liquid chromatography (HPLC) provides unique detailed information regarding the structure of partially disordered or amorphous phosphate solids. Applications of the experimental technique of HPLC to phosphate solids are reviewed, and examples of the type of information that can be obtained with HPLC are presented. Inorganic phosphates encompass a large class of important materials whose applications include: catalysts, ion-exchange media, solid electrolytes for batteries, linear and nonlinear optical components, chelating agents, synthetic replacements for bone and teeth, phosphors, detergents, and fertilizers. Phosphate ions also represent a unique link between living systems and the inorganic world.

  14. Determination of deoxynivalenol and deoxynivalenol-3-glucoside in wheat and barley using liquid chromatography coupled to mass spectrometry: on-line clean-up versus conventional sample preparation techniques.

    PubMed

    Nathanail, Alexis V; Sarikaya, Ebru; Jestoi, Marika; Godula, Michal; Peltonen, Kimmo

    2014-12-29

    In this study, we compared the performance of conventional sample preparation techniques used in mycotoxin analyses against automated on-line sample clean-up for the determination of deoxynivalenol (DON) and its conjugated derivative, deoxynivalenol-3-β-d-glucoside (D3G), in cereal grains. Blank wheat and barley samples were spiked with DON and D3G, extracted with a mixture of acetonitrile:water (84:16, v/v) and processed by one of the following: extract and shoot, MycoSep(®) 227 clean-up columns, MycoSep 227 with an additional acetonitrile elution step and centrifugal filtration, followed by analysis with liquid chromatography tandem mass spectrometry. Based on method performance characteristics and poor recoveries (<30%) obtained for the polar D3G with some techniques, the extract and shoot approach was chosen for the inter-laboratory method comparison study. Thus, the same spiked samples were analysed in parallel by another laboratory with an in-house validated on-line sample clean-up method, utilising TurboFlow™ chromatography coupled to high resolution mass spectrometry. Method validation was performed by determination of specificity, linearity, recovery, intra-day precision and the limits of detection and quantification. Matrix-matched linearity (R(2)>0.985) was established in the range of 100-1600 and 20-320μg/kg for DON and D3G, respectively. Average recoveries (%RSD) were acceptable with both methods for wheat and barley, ranging between 73% and 102% (3-12%) for DON and 72% and 98% (1-10%) for D3G. The benefit of using automated sample clean-up in comparison to extract and shoot is the ability to inject directly pure extracts into the mass spectrometer, offering faster analyses and improved sensitivity with minimum system maintenance.

  15. Instrumentation for hand-portable liquid chromatography.

    PubMed

    Sharma, Sonika; Plistil, Alex; Simpson, Robert S; Liu, Kun; Farnsworth, Paul B; Stearns, Stanley D; Lee, Milton L

    2014-01-31

    Liquid chromatography (LC) has lagged behind gas chromatography (GC) in developments related to hand-portable instrumentation. In this work, a new battery-operated (24V DC) nano-flow pumping system with a stop-flow injector was developed and integrated with an on-column UV-absorption detector (254nm) that was reduced in size to an acceptable weight and power usage for field operation. The pumping system, which includes nano-flow pump, stepper motor and high-pressure valve weighs only 1.372kg (3lbs) and can generate up to 110.32MPa (16,000psi) pressure. A major advantage of this pump is that it does not employ a splitter, since it was specifically designed for capillary column use. The volume capacity of the pump is 24μL, and a sample volume as low as 10nL can be injected. Flow rate calibration (300nL to 6.12μL per min) was performed, and an accuracy >99.94% was obtained. The percent injection carry-over was found to be low (RSD 0.31%), which makes it practical for quantitative analysis. The detector linear range and limit of detection (LOD) were determined using sodium anthraquinone-2-sulfonate. A linear regression coefficient (R) of 0.9996 was obtained for a plot of log peak area versus log concentration over the range of 3.2μM to 6.5mM, and the LOD (S/N=3) was found to be 7.8fmol (0.13μM). The short term noise of the detector is comparable to commercially available detectors (∼10(-5)AU). In this work, the system was tested in the laboratory using regular line power (120V AC) with an AC to DC adapter. Reversed-phase isocratic separations were performed using a 15.5cm×75μm i.d. fused silica capillary column containing a monolithic stationary phase synthesized from 1,6-hexanediol dimethacrylate. Good retention time repeatability (RSD 0.09-0.74%) was obtained for a mixture containing an unretained marker (i.e., uracil) and a homologous series of alkyl benzenes.

  16. High Performance Liquid Chromatography of Vitamin A: A Quantitative Determination.

    ERIC Educational Resources Information Center

    Bohman, Ove; And Others

    1982-01-01

    Experimental procedures are provided for the quantitative determination of Vitamin A (retinol) in food products by analytical liquid chromatography. Standard addition and calibration curve extraction methods are outlined. (SK)

  17. Ion Exchange and Liquid Column Chromatography.

    ERIC Educational Resources Information Center

    Walton, Harold F.

    1980-01-01

    Emphasizes recent advances in principles and methodology in ion exchange and chromatography. Two tables list representative examples for inorganic ions and organic compounds. Cites 544 references. (CS)

  18. Dehydroepiandrosterone sulfate quantification in serum using high-performance liquid chromatography/mass spectrometry and a deuterated internal standard: a technique suitable for routine use or as a reference method

    SciTech Connect

    Shackleton, C.H.; Kletke, C.; Wudy, S.; Pratt, J.H. )

    1990-10-01

    A thermospray high-performance liquid chromatography/mass spectrometry method for determination of serum dehydroepiandrosterone sulfate is described. The steroid was measured intact using (7,7-2H2)dehydroepiandrosterone sulfate as internal standard. The analysis was carried out in the negative ion mode by determining the peak height ratio of the molecular anions of the analyte and internal standard. The method was used to determine the steroid in serum from 15 male and female normal adults and the following values were obtained: males, 272 +/- 45 micrograms/dl (range, 197 to 331 micrograms/dl) and females, 215 +/- 67 micrograms/dl (range, 107 to 347 micrograms/dl). In addition, dehydroepiandrosterone sulfate was measured by high-performance liquid chromatography/mass spectrometry and radioimmunoassay (a commercial kit) on 25 individuals of all age groups. There was strong correlation between the values obtained, but the radioimmunoassay values were generally double those obtained by high-performance liquid chromatography/mass spectrometry. Three other steroid sulfates, androsterone sulfate, epiandrosterone sulfate, and androst-5-ene-3 beta, 17 beta-diol sulfate, were also assayed. In males, these had mean values of 112, 44, and 13 micrograms/dl and, in females, they had mean values of 84, 25, and 6 micrograms/dl, respectively. Radioimmunoassay cross-reactivity measurement for these steroids (as reference compounds) showed that they were unlikely to contribute greatly to the discrepancy between radioimmunoassay and high-performance liquid chromatography/mass spectrometry values.

  19. Exploring the potentialities of an improved ultrasound-assisted quick, easy, cheap, effective, rugged, and safe-based extraction technique combined with ultrahigh pressure liquid chromatography-fluorescence detection for determination of Zearalenone in cereals.

    PubMed

    Porto-Figueira, Priscilla; Camacho, Irene; Câmara, José S

    2015-08-21

    Zearalenone (ZEA), a secondary metabolite from Fusarium graminearum fungi that invade crops and grow during blooming in moist cool field conditions, is a nonsteroidal oestrogen, biologically very potent, although hardly toxic. Different analytical methods, among which a quick, easy, cheap, effective, rugged, and safe (QuEChERS) strategy, combined with or liquid chromatography, have been proposed for ZEA determination in foods. However, this extraction procedure has the disadvantage of using large amount of organic solvents, partitioning salts and sample volume, which limits the technique application on the fields where the sample amount is critical. Therefore in this work an improved sample preparation step based on the original QuEChERS (O-QuEChERS) approach, the μ-QuEChERS, combined with ultrasound-assisted extraction (USAE) and ultrahigh pressure liquid chromatography (UHPLC) analysis with fluorescence detection (FLR) is proposed for the sensitive and high-throughput quantification of ZEA in cereals. The proposed analytical strategy, μ-QuEChERSUSAE, uses up to 32 times lower amounts of partitioning salts, lower sample amount and lower extraction solvents, in comparison with O-QuEChERS technique. The performance of the analytical approach was assessed by studying the selectivity, specificity, limits of detection and quantification, linear dynamic range, matrix effect and precision. Good linearity (r(2)>0.99) was achieved for ZEA, and limits of detection (LOD=3.4μgkg(-1)) and limits of quantification (LOQ=4.7μgkg(-1)) were found below the tolerance levels set by European Commission. Good recoveries were obtained with different spiked concentrations, ranged from 80.2% to 109.7%, with relative standard deviations (RSD) lower than 5.0%. The comparison of the analytical performance of the proposed μ-QuEChERSUSAE with O-QuEChERS showed the powerful ability of the proposed strategy since it gives comparable results but using lower amounts of sample, partitioning

  20. Exploring the potentialities of an improved ultrasound-assisted quick, easy, cheap, effective, rugged, and safe-based extraction technique combined with ultrahigh pressure liquid chromatography-fluorescence detection for determination of Zearalenone in cereals.

    PubMed

    Porto-Figueira, Priscilla; Camacho, Irene; Câmara, José S

    2015-08-21

    Zearalenone (ZEA), a secondary metabolite from Fusarium graminearum fungi that invade crops and grow during blooming in moist cool field conditions, is a nonsteroidal oestrogen, biologically very potent, although hardly toxic. Different analytical methods, among which a quick, easy, cheap, effective, rugged, and safe (QuEChERS) strategy, combined with or liquid chromatography, have been proposed for ZEA determination in foods. However, this extraction procedure has the disadvantage of using large amount of organic solvents, partitioning salts and sample volume, which limits the technique application on the fields where the sample amount is critical. Therefore in this work an improved sample preparation step based on the original QuEChERS (O-QuEChERS) approach, the μ-QuEChERS, combined with ultrasound-assisted extraction (USAE) and ultrahigh pressure liquid chromatography (UHPLC) analysis with fluorescence detection (FLR) is proposed for the sensitive and high-throughput quantification of ZEA in cereals. The proposed analytical strategy, μ-QuEChERSUSAE, uses up to 32 times lower amounts of partitioning salts, lower sample amount and lower extraction solvents, in comparison with O-QuEChERS technique. The performance of the analytical approach was assessed by studying the selectivity, specificity, limits of detection and quantification, linear dynamic range, matrix effect and precision. Good linearity (r(2)>0.99) was achieved for ZEA, and limits of detection (LOD=3.4μgkg(-1)) and limits of quantification (LOQ=4.7μgkg(-1)) were found below the tolerance levels set by European Commission. Good recoveries were obtained with different spiked concentrations, ranged from 80.2% to 109.7%, with relative standard deviations (RSD) lower than 5.0%. The comparison of the analytical performance of the proposed μ-QuEChERSUSAE with O-QuEChERS showed the powerful ability of the proposed strategy since it gives comparable results but using lower amounts of sample, partitioning

  1. Analysis of global components in Ganoderma using liquid chromatography system with multiple columns and detectors.

    PubMed

    Qian, Zhengming; Zhao, Jing; Li, Deqiang; Hu, Dejun; Li, Shaoping

    2012-10-01

    In present study, a multiple columns and detectors liquid chromatography system for analysis of global components in traditional Chinese medicines was developed. The liquid chromatography system was consist of three columns, including size exclusion chromatography column, hydrophilic interaction chromatography column, and reversed phase chromatography column, and three detectors, such as diode array detector, evaporative light scattering detector, and mass spectrometry detector, based on column switching technique. The developed multiple columns and detectors liquid chromatography system was successfully applied to the analysis of global components, including macromolecular (polysaccharides), high (nucleosides and sugars)-, and low (triterpenes)-polarity small molecular compounds in Ganoderma, a well-known Chinese medicinal mushroom. As a result, one macromolecular chromatographic peak was found in two Ganoderma species, 19 components were identified in Ganoderma lucidum (two sugars, three nucleosides, and 14 triterpenes), and four components (two sugars and two nucleosides) were identified in Ganoderma sinense. The developed multiple columns and detectors liquid chromatography system was helpful to understand comprehensive chemical characters in TCMs.

  2. Determination of tetraalkyllead compounds in gasoline by liquid chromatography-atomic absorption spectrometry

    USGS Publications Warehouse

    Messman, J.D.; Rains, T.C.

    1981-01-01

    A liquid chromatography-atomic absorption spectrometry (LC-AAS) hybrid analytical technique is presented for metal speciation measurements on complex liquid samples. The versatility and inherent metal selectivity of the technique are Illustrated by the rapid determination of five tetraalkyllead compounds in commercial gasoline. Separation of the individual tetraalkyllead species is achieved by reversed-phase liquid chromatography using an acetonitrile/water mobile phase. The effluent from the liquid Chromatograph Is introduced directly into the aspiration uptake capillary of the nebulizer of an air/acetylene flame atomic absorption spectrometer. Spectral interferences due to coeluting hydrocarbon matrix constituents were not observed at the 283.3-nm resonance line of lead used for analysis. Detection limits of this LC-AAS hydrid analytical technique, based on a 20-??L injection, are approximately 10 ng Pb for each tetraalkyllead compound.

  3. Ultrapure water for liquid chromatography-mass spectrometry studies.

    PubMed

    Regnault, Cecilia; Kano, Ichiro; Darbouret, Daniel; Mabic, Stéphane

    2004-03-19

    Improvements in trace enrichment techniques combined with the sensitivity of mass spectrometry offer enhanced opportunities to analyze ever lower concentrations of drugs, metabolites, pesticides or environmental pollutants. To perform HPLC and liquid chromatography-mass spectrometry (LC-MS) analyses under optimum conditions, the water used for mobile phase preparation needs to be highly purified and delivered on demand. Indeed, both UV photodiode array detection and MS detection methods are sensitive to organic contaminants (total organic carbon, TOC), and the water quality has a direct impact on the achievable detection limits. The benefits of UV photooxidation on TOC reduction for LC-MS studies were highlighted using electrospray ionization MS detection by comparing HPLC-grade bottled water, freshly produced UV185/254-treated water, and freshly produced non-UV-treated water.

  4. Metabolic profile of 5-hydroxy-4-methoxycanthin-6-one, a typical canthinone alkaloid, in rats determined by liquid chromatography-quadrupole time-of-flight tandem mass spectrometry together with multiple data processing techniques.

    PubMed

    Shi, Yuanyuan; Xia, Yuanyuan; Wang, Jueyu; He, Jinfeng; Feng, Feng; Liu, Wenyuan

    2016-09-10

    Picrasma quassioides (D. Don) Benn. is a traditional Chinese medicine used clinically to treat gastrointestinal disorders and as a vermifuge. 5-Hydroxy-4-methoxycanthin-6-one (CAN), a major canthinone alkaloid found in P. quassioides, has significant pharmacological activities. In the present study, a method using liquid chromatography-quadrupole time-of-flight tandem mass spectrometry together with multiple data processing techniques, including extracted ion chromatogram, multiple mass defect filter, precursor/product ion scanning and neutral loss scanning was developed to screen and characterize the phase I and II metabolites of CAN in plasma, bile, urine and feces of rats after a single oral dose of 20mg/kg. A total of 17 metabolites were tentatively or conclusively identified. Pathways for the metabolism of CAN have been proposed, and include hydroxylation, N-decarbonylation, methylation, oxidation and sequential conjugation. A previously unknown metabolically active site at the C4-C6 position and a novel N-decarbonylation-oxidation metabolic pathway for the prototypical canthinone alkaloid, CAN, were discovered. Our results provide valuable information about the in vivo metabolism of CAN that can also be used as a comprehensive guide for the biotransformation of other canthinone alkaloids.

  5. Screening and analysis of the multiple absorbed bioactive components and metabolites of Baihe Zhimu Tang by the metabolic fingerprinting technique and liquid chromatography/diode array detection-electrospray ionization-mass spectrometry

    PubMed Central

    Qin, Kunming; Cai, Hao; Liu, Xiao; Lu, Tulin; Fang, Qianbo; Yao, Zhongqing; Xu, Zisheng; Cai, Baochang

    2011-01-01

    Background: Baihe Zhimu Tang (BZT) is a widely used traditional Chinese medicinal formula in treating various diseases; however, its active components have remained unknown. Materials and Methods: Based on the metabolic fingerprinting technique and liquid chromatography/diode array detection-electrospray ionization-mass spectrometry (LC/DAD-ESI-MS), a method for rapid screening and analysis of the multiple absorbed bioactive components and metabolites of an oral solution of Baihe Zhimu Tang (BZT) in rabbit plasma, urine and feces after oral administration of BZT was developed. Results: The results obtained from a comprehensive comparative analysis of the fingerprints of the BZT and its metabolic fingerprints in rabbit biological samples indicated that 19 components in the BZT were absorbed into the rabbit's body. Both of them were tentatively identified from their MS and UV spectra and retention behaviors by comparing the results with the reported literature. In addition, only six components were found in the metabolic fingerprints, which suggested that they might be metabolites of some components in the BZT. Conclusion: The findings demonstrated that the proposed method could be used to rapidly and simultaneously analyze and screen the multiple absorbed bioactive constituents and metabolites in a formula of traditional Chinese medicines (TCMs) by comparing and contrasting the chromatographic fingerprints with its metabolic fingerprints. This is very important not only for the pharmaceutical discovery process and the quality control of crude drugs, but also for explaining the curative mechanism of TCMs. PMID:21969787

  6. Ultra high performance liquid chromatography tandem mass spectrometry method for the simultaneous determination of multiple bioactive constituents in fruit extracts of Myristica fragrans and its marketed polyherbal formulations using a polarity switching technique.

    PubMed

    Pandey, Renu; Rameshkumar, Koranappallil Bahuleyan; Kumar, Brijesh

    2015-05-01

    Fruits of Myristica fragrans Houtt. are the source of two valuable spices: nutmeg and mace, traditionally used for its flavoring and medicinal properties and found as an ingredient in many marketed polyherbal formulations and food products. In this study, a sensitive and efficient ultra high performance liquid chromatography electrospray ionization tandem mass spectrometry method was developed and validated for the rapid determination of 16 bioactive constituents in different parts of the fruit of M. fragrans and its marketed polyherbal formulations using a polarity switching technique. Chromatographic separation was achieved on an Aquity UPLC BEH C18 column in 9.4 min. Quantitative analysis was performed using multiple reaction monitoring mode with continuous polarity switching in a single analysis. The developed method was found to be accurate with overall recovery in the range from 95.95 to 102.07% (RSD ≤ 1.91%), precise (RSD ≤ 1.98%), and linear (r(2) ≥ 0.9992) over the concentration range of 0.1-200 ng/mL. Quantitative analysis indicated that the total content of the 16 bioactive constituents was highest in the mace of M. fragrans. Thus, this rapid and sensitive method could be utilized as a promising reference method for the quality control of M. fragrans and its marketed herbal formulations/food products.

  7. Screening and identification of multiple constituents and their metabolites of Fangji Huangqi Tang in rats by ultra-high performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry basing on coupling data processing techniques.

    PubMed

    Wang, Xiaoli; Liu, Xiao; Xu, Xiaoyan; Zhu, Tingting; Shi, Fa; Qin, Kunming; Cai, Baochang

    2015-03-15

    Fangji Huangqi Tang (FHT) is a classical formula widely used in Chinese clinical application. In this paper, a novel and advanced strategy has been developed for the multiple constituent identification of FHT in rats, which was basing on an ultra-high performance liquid chromatography equipped with electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC-ESI-Q-TOF-MS) method combined with dynamic background subtract (DBS) data acquisition and enhance peak list (EPL) data processing techniques. Firstly, a total of 58 potential bioactive compounds including alkaloids, flavonoids, saponins, saccharides and terpenoids were detected from FHT. Their chemical structures were identified by comparing the retention time and mass spectrometry data, as well as retrieving the reference literatures. Based on the same instrumental conditions, 33 compounds were found in rat serum after oral administration of FHT. After a considerate comparison with the former chemical identification results of FHT, 33 compounds were found, which turned out to be 8 original compounds of FHT as well as 25 metabolites, including 20 phase I and 5 phase II metabolites. The results indicated that the metabolic reactions included hydroxylation, hydrogenation, demethylation, tarine conjugation and acetylation. This study firstly reported the metabolism description of fangchinoline and tetrandrine in vivo, which could be very useful for further pharmacological and clinical studies of FHT. Meanwhile, it provided a practical strategy for rapid screening and identifying of multiple constituents and their metabolites of complex traditional Chinese medicine in biological matrix. PMID:25656758

  8. Ultra high performance liquid chromatography tandem mass spectrometry method for the simultaneous determination of multiple bioactive constituents in fruit extracts of Myristica fragrans and its marketed polyherbal formulations using a polarity switching technique.

    PubMed

    Pandey, Renu; Rameshkumar, Koranappallil Bahuleyan; Kumar, Brijesh

    2015-05-01

    Fruits of Myristica fragrans Houtt. are the source of two valuable spices: nutmeg and mace, traditionally used for its flavoring and medicinal properties and found as an ingredient in many marketed polyherbal formulations and food products. In this study, a sensitive and efficient ultra high performance liquid chromatography electrospray ionization tandem mass spectrometry method was developed and validated for the rapid determination of 16 bioactive constituents in different parts of the fruit of M. fragrans and its marketed polyherbal formulations using a polarity switching technique. Chromatographic separation was achieved on an Aquity UPLC BEH C18 column in 9.4 min. Quantitative analysis was performed using multiple reaction monitoring mode with continuous polarity switching in a single analysis. The developed method was found to be accurate with overall recovery in the range from 95.95 to 102.07% (RSD ≤ 1.91%), precise (RSD ≤ 1.98%), and linear (r(2) ≥ 0.9992) over the concentration range of 0.1-200 ng/mL. Quantitative analysis indicated that the total content of the 16 bioactive constituents was highest in the mace of M. fragrans. Thus, this rapid and sensitive method could be utilized as a promising reference method for the quality control of M. fragrans and its marketed herbal formulations/food products. PMID:25631526

  9. Vortex and air assisted liquid-liquid microextraction as a sample preparation method for high-performed liquid chromatography determinations.

    PubMed

    Hosseini, Mohammad; Heydari, Rouhollah; Alimoradi, Mohammad

    2014-12-01

    A novel, simple and sensitive method based on vortex and air assisted liquid-liquid microextraction (VAALLME) technique coupled with high-performance liquid chromatography (HPLC) has been developed for quantitative analysis of β-naphthol, naphthalene and anthracene as model analytes. Unlike the dispersive liquid-liquid microextraction (DLLME), dispersive solvent and centrifuging step were eliminated in proposed technique. In this technique, extraction solvent was dispersed into the aqueous sample solution by using vortex. Phase separation was achieved via motion of air bubbles from the bottom to top of the extraction tube, which promoted the analytes transfer into the supernatant organic phase. Influential parameters on the extraction efficiency such as type and volume of extraction solvent, salt type and its concentration, vortex and aeration times, and sample pH were evaluated and optimized. The calibration curves showed good linearity (r(2)>0.9947) and precision (RSD<5.0%) in the working concentration ranges. The limit of detection (LOD) for β-naphthol, naphthalene and anthracene were 10, 5.0 and 0.5 ng mL(-1), respectively. The recoveries were in the range of 97.0-102.0% with RSD values ranging from 2.2 to 5.2%.

  10. Group type analysis of asphalt by column liquid chromatography

    SciTech Connect

    Zhang, C.; Yang, J.; Xue, Y.; Li, Y.

    2008-07-01

    An improved analysis method for characterization of asphalt was established. The method is based on column chromatography technique. The asphalts were separated into four groups: saturates, aromatics, resins, and asphaltenes, quantitatively. About 0.1 g of sample was required in each analysis. About 20 mL of n-heptanes was used to separate out saturates first. Then about 35 mL of n-heptanes/dichloromethane (.5, v/v) mixture was used to separate out aromatics. About 30 mL of dichloromethane/tetrahydrofuran (1/3, v/v) mixture was used to separate out resin. The quality of the separation was confirmed by infrared spectra (IR) and {sup 1}H NMR analysis. The model compounds, tetracosan for saturates, dibenz(o)anthracen for aromatics, and acetanilide for resins were used for verification. The IR and {sup 1}H NMR analysis of the prepared fractions from the column liquid chromatography were in good agreement that of pure reagents.

  11. Identification of Explosives from Porous Materials: Applications Using Reverse Phase High Performance Liquid Chromatography and Gas Chromatography

    SciTech Connect

    C.J. Miller; G. Elias; N.C. Schmitt; C. Rae

    2010-06-01

    High performance liquid chromatography and gas chromatography techniques are well documented and widely used for the detection of trace explosives from organic solvents. These techniques were modified to specifically identify and quantify explosives extracted from various materials taken from people who had recently handled explosives. Documented techniques were modified to specifically detect and quantify RDX, TNT, and PETN from denim, colored flannel, vinyl, and canvas extracted in methanol using no sample cleanup prior to analysis. The methanol extracts were injected directly into several different column types and analyzed by HPLC-UV and/or GC-ECD. This paper describes general screening methods that were used to determine the presence of explosives in unknown samples and techniques that have been optimized for quantification of each explosive from the substrate extracts.

  12. Applying Chromatography.

    ERIC Educational Resources Information Center

    Klein, Jessie W.; Patev, Paul

    1998-01-01

    Presents three experiments to introduce students to different kinds of chromatography: (1) paper chromatography; (2) gel filtration chromatography; and (3) reverse-phase liquid chromatography. Written in the form of a laboratory manual, explanations of each of the techniques, materials needed, procedures, and a glossary are included. (PVD)

  13. Towards Chip Scale Liquid Chromatography and High Throughput Immunosensing

    SciTech Connect

    Ni, J.

    2000-09-21

    This work describes several research projects aimed towards developing new instruments and novel methods for high throughput chemical and biological analysis. Approaches are taken in two directions. The first direction takes advantage of well-established semiconductor fabrication techniques and applies them to miniaturize instruments that are workhorses in analytical laboratories. Specifically, the first part of this work focused on the development of micropumps and microvalves for controlled fluid delivery. The mechanism of these micropumps and microvalves relies on the electrochemically-induced surface tension change at a mercury/electrolyte interface. A miniaturized flow injection analysis device was integrated and flow injection analyses were demonstrated. In the second part of this work, microfluidic chips were also designed, fabricated, and tested. Separations of two fluorescent dyes were demonstrated in microfabricated channels, based on an open-tubular liquid chromatography (OT LC) or an electrochemically-modulated liquid chromatography (EMLC) format. A reduction in instrument size can potentially increase analysis speed, and allow exceedingly small amounts of sample to be analyzed under diverse separation conditions. The second direction explores the surface enhanced Raman spectroscopy (SERS) as a signal transduction method for immunoassay analysis. It takes advantage of the improved detection sensitivity as a result of surface enhancement on colloidal gold, the narrow width of Raman band, and the stability of Raman scattering signals to distinguish several different species simultaneously without exploiting spatially-separated addresses on a biochip. By labeling gold nanoparticles with different Raman reporters in conjunction with different detection antibodies, a simultaneous detection of a dual-analyte immunoassay was demonstrated. Using this scheme for quantitative analysis was also studied and preliminary dose-response curves from an immunoassay of a

  14. Determination of cyclamate by high-performance liquid chromatography with indirect photometry.

    PubMed

    Herrmann, A; Damawandi, E; Wagmann, M

    1983-12-01

    Most artificial sweeteners have been determined by high-performance liquid chromatography, but not cyclamate. We propose a simple method using standard equipment without any chemical reaction involving the cyclamate ion by applying the technique of indirect photometry. Saccharin, dulcin and aspartame may also be determined, if present.

  15. High Performance Liquid Chromatography of Some Analgesic Compounds: An Instrumental Analysis Experiment.

    ERIC Educational Resources Information Center

    Haddad, Paul; And Others

    1983-01-01

    Background information, procedures, and results are provided for an experiment demonstrating techniques of solvent selection, gradient elution, pH control, and ion-pairing in the analysis of an analgesic mixture using reversed-phase liquid chromatography on an octadecylsilane column. Although developed using sophisticated/expensive equipment, less…

  16. High-performance liquid chromatography of oligoguanylates at high pH

    NASA Technical Reports Server (NTRS)

    Stribling, R.; Deamer, D. (Principal Investigator)

    1991-01-01

    Because of the stable self-structures formed by oligomers of guanosine, standard high-performance liquid chromatography techniques for oligonucleotide fractionation are not applicable. Previously, oligoguanylate separations have been carried out at pH 12 using RPC-5 as the packing material. While RPC-5 provides excellent separations, there are several limitations, including the lack of a commercially available source. This report describes a new anion-exchange high-performance liquid chromatography method using HEMA-IEC BIO Q, which successfully separates different forms of the guanosine monomer as well as longer oligoguanylates. The reproducibility and stability at high pH suggests a versatile role for this material.

  17. Carbon nanotube reinforced hollow fiber solid/liquid phase microextraction: a novel extraction technique for the measurement of caffeic acid in Echinacea purpurea herbal extracts combined with high-performance liquid chromatography.

    PubMed

    Es'haghi, Zarrin; Golsefidi, Mazyar Ahmadi; Saify, Ali; Tanha, Ali Akbar; Rezaeifar, Zohre; Alian-Nezhadi, Zahra

    2010-04-23

    A new design of hollow fiber solid-liquid phase microextraction (HF-SLPME) was developed for the determination of caffeic acid in medicinal plants samples as Echinacea purpure. The membrane extraction with sorbent interface used in this research is a three-phase supported liquid membrane consisting of an aqueous (donor phase), organic solvent/nano sorbent (membrane) and aqueous (acceptor phase) system operated in direct immersion sampling mode. The multi-walled carbon nanotube dispersed in the organic solvent is held in the pores of a porous membrane supported by capillary forces and sonification. It is in contact with two aqueous phases: the donor phase, which is the aqueous sample, and the acceptor phase, usually an aqueous buffer. All microextraction experiments were supported using an Accurel Q3/2 polypropylene hollow fiber membrane (600 microm I.D., 200 microm wall thicknesses, and 0.2 microm pore size). The experimental setup is very simple and highly affordable. The hollow fiber is disposable, so single use of the fiber reduces the risk of cross-contamination and carry-over problems. The proposed method allows the very effective and enriched recuperation of an acidic analyte into one single extract. In order to obtain high enrichment and extraction efficiency of the analyte using this novel technique, the main parameters were optimized. Under the optimized extraction conditions, the method showed good linearity (0.0001-50 microg/L), repeatability, low limits of detection (0.00005 microg/L) and excellent enrichment (EF=2108). PMID:20227700

  18. Micro-polarimeter for high performance liquid chromatography

    DOEpatents

    Yeung, Edward E.; Steenhoek, Larry E.; Woodruff, Steven D.; Kuo, Jeng-Chung

    1985-01-01

    A micro-polarimeter interfaced with a system for high performance liquid chromatography, for quantitatively analyzing micro and trace amounts of optically active organic molecules, particularly carbohydrates. A flow cell with a narrow bore is connected to a high performance liquid chromatography system. Thin, low birefringence cell windows cover opposite ends of the bore. A focused and polarized laser beam is directed along the longitudinal axis of the bore as an eluent containing the organic molecules is pumped through the cell. The beam is modulated by air gap Faraday rotators for phase sensitive detection to enhance the signal to noise ratio. An analyzer records the beams's direction of polarization after it passes through the cell. Calibration of the liquid chromatography system allows determination of the quantity of organic molecules present from a determination of the degree to which the polarized beam is rotated when it passes through the eluent.

  19. Performance of the same column in supercritical fluid chromatography and in liquid chromatography.

    PubMed

    Lambert, Nándor; Felinger, Attila

    2015-08-28

    We have studied the chromatographic behavior of the homologous series of alkylbenzenes (ranging from octylbenzene to octadecylbenzene) on the same C18 reversed-phase column in supercritical fluid chromatography (SFC) and reversed phase liquid chromatography (RPLC) at various experimental conditions, such as different eluent compositions, flow-rates, and mobile phase densities. The first and the second moments of the peaks were used to estimate the overall mass-transfer processes in both chromatographic modes using the stochastic model of chromatography. The results confirm that in SFC - as the density of the mobile phase is influenced by the flow-rate - there is a broader variation of mass-transfer properties than in liquid chromatography. As expected, the optimum mobile phase velocity is higher in SFC, but there is no real difference in the minimum value of plate height, i.e. in the optimum efficiency.

  20. Dispersive liquid-liquid-liquid microextraction combined with liquid chromatography for the determination of chlorophenoxy acid herbicides in aqueous samples.

    PubMed

    Tsai, Wan-Chun; Huang, Shang-Da

    2009-11-01

    A novel sample preparation method "Dispersive liquid-liquid-liquid microextraction" (DLLLME) was developed in this study. DLLLME was combined with liquid chromatography system to determine chlorophenoxy acid herbicide in aqueous samples. DLLLME is a rapid and environmentally friendly sample pretreatment method. In this study, 25microL of 1,1,2,2-tetrachloroethane was added to the sample solution and the targeted analytes were extracted from the donor phase by manually shaking for 90s. The organic phase was separated from the donor phase by centrifugation and was transferred into an insert. Acceptor phase was added to this insert. The analytes were then back-extracted into the acceptor phase by mixing the organic and acceptor phases by pumping those two solutions with a syringe plunger. After centrifugation, the organic phase was settled and removed with a microsyringe. The acceptor phase was injected into the UPLC system by auto sampler. Fine droplets were formed by shaking and pumping with the syringe plunger in DLLLME. The large interfacial area provided good extraction efficiency and shortened the extraction time needed. Conventional LLLME requires an extraction time of 40-60min; an extraction time of approximately 2min is sufficient with DLLLME. The DLLLME technique shows good linearity (r(2)>or=0.999), good repeatability (RSD: 4.0-12.2% for tap water; 5.7-8.5% for river water) and high sensitivity (LODs: 0.10-0.60microg/L for tap water; 0.11-0.95microg/L for river water).

  1. Serum theophylline analysis by high-pressure liquid chromatography.

    PubMed

    Evenson, M A; Warren, B L

    1976-06-01

    We have developed and evaluated a rapid, high-pressure liquid-chromatographic method for theophylline in serum. Only 0.2 ml of serum is required for each determination, and the sensitivity of this method is 0.5 mg/liter. This method, involving liquid extraction and silica adsorption chromatography, provides adequate selectivity, accuracy, and precision for routine or research applications. Little sample preparation is required before chromatography. We found no endogenous or exogenous interferences. Use of beta-hydroxypropyl theophylline as the internal standard provides reproducible results for this micro-scale method.

  2. Neuere Chromatographie

    NASA Astrophysics Data System (ADS)

    Hostettmann, K.

    1983-04-01

    Besides high-performance liquid chromatography (HPLC) which is now a well-established and currently used technique, several emerging methods for the isolation and separation of natural products are receiving considerable attention. Centrifugal thin-layer chromatography is a very rapid technique, but limited in resolution. Of special interest are the recently developed support-free liquid-liquid chromatography methods such as droplet counter-current chromatography (DCCC) and rotation locular counter-current chromatography (RLCC). This latter method was applied to the separation of the enantiomers of (±)-norephedrine.

  3. Analysis of steroids in yeast-mediated cell culture by on-line solid-phase extraction coupled high-performance liquid chromatography electrospray-ionization/mass spectrometry and novel continuous postcolumn infusion of internal standard technique.

    PubMed

    Cheng, Cheanyeh; Tsai, Hsiang-Rong

    2008-08-15

    The reduction of 17-ketosteroid estrone or androstenedione to corresponding 17alpha- and 17beta-estradiol or testosterone and epitestosterone has been performed with Saccharomyces cerevisiae. In the analysis of the cell culture, the solid-phase extraction (SPE) method was on-line coupled to high-performance liquid chromatography electrospray-ionization/mass spectrometry (HPLC-ESI/MS) for sample pretreatment to eliminate the complicated matrix interference and preconcentrate of the analytes before chromatographic separation. A novel quantification method with the continuous postcolumn infusion of internal standard was developed for the determination of substrate and products. This novel quantitative method can stabilize and enhance the ionization of all analytes during analysis. The HPLC-ESI/MS analysis of estrone, 17alpha-, and 17beta-estradiol was operated with a negative ion mode and the analysis of androstenedione, testosterone, and epitestosterone was operated with a positive ion mode. The optimal concentration of the internal standard progesterone with the continuous postcolumn infusion technique was 3 microg mL(-1) for estrogen analysis and 1 ng mL(-1) for androgen analysis and both were at a constant infusion rate of 0.5 microL min(-1). All of the linear correlation coefficients of the standard calibration curves were over 0.99 and had a linear range from 0 to 50 ng mL(-1). The limit of detections (LODs) and the limit of quantitations (LOQs) for steroids analyzed were from 0.12 to 0.36 ng mL(-1) and from 0.4 to 1.2 ng mL(-1), respectively. The analysis accuracies and precisions were better than 94% and lower than 8.8% R.S.D., respectively. The developed method for the analysis of steroids in the cell culture was successful.

  4. Harmonization of the quantitative determination of volatile fatty acids profile in aqueous matrix samples by direct injection using gas chromatography and high-performance liquid chromatography techniques: Multi-laboratory validation study.

    PubMed

    Raposo, Francisco; Borja, Rafael; Cacho, Jesús A; Mumme, Jan; Mohedano, Ángel F; Battimelli, Audrey; Bolzonella, David; Schuit, Anthony D; Noguerol-Arias, Joan; Frigon, Jean-Claude; Peñuela, Gustavo A; Muehlenberg, Jana; Sambusiti, Cecilia

    2015-09-25

    The performance parameters of volatile fatty acids (VFAs) measurements were assessed for the first time by a multi-laboratory validation study among 13 laboratories. Two chromatographic techniques (GC and HPLC) and two quantification methods such as external and internal standard (ESTD/ISTD) were combined in three different methodologies GC/ESTD, HPLC/ESTD and GC/ISTD. Linearity evaluation of the calibration functions in a wide concentration range (10-1000mg/L) was carried out using different statistical parameters for the goodness of fit. Both chromatographic techniques were considered similarly accurate. The use of GC/ISTD, despite showing similar analytical performance to the other methodologies, can be considered useful for the harmonization of VFAs analytical methodology taking into account the normalization of slope values used for the calculation of VFAs concentrations. Acceptance criteria for VFAs performance parameters of the multi-laboratory validation study should be established as follows: (1) instrument precision (RSDINST≤1.5%); (2) linearity (R(2)≥0.998; RSDSENSITIVITY≤4%; REMAX≤8%; REAVER≤ 3%); (3) precision (RSD≤1.5%); (4) trueness (recovery of 97-103%); (5) LOD (≤3mg/L); and (6) LOQ (10mg/L).

  5. Liquid Chromatography-Mass Spectrometry-based Quantitative Proteomics

    SciTech Connect

    Xie, Fang; Liu, Tao; Qian, Weijun; Petyuk, Vladislav A.; Smith, Richard D.

    2011-07-22

    Liquid chromatography-mass spectrometry (LC-MS)-based quantitative proteomics has become increasingly applied for a broad range of biological applications due to growing capabilities for broad proteome coverage and good accuracy in quantification. Herein, we review the current LC-MS-based quantification methods with respect to their advantages and limitations, and highlight their potential applications.

  6. Multichannel Detection in High-Performance Liquid Chromatography.

    ERIC Educational Resources Information Center

    Miller, James C.; And Others

    1982-01-01

    A linear photodiode array is used as the photodetector element in a new ultraviolet-visible detection system for high-performance liquid chromatography (HPLC). Using a computer network, the system processes eight different chromatographic signals simultaneously in real-time and acquires spectra manually/automatically. Applications in fast HPLC…

  7. Quantification of Tea Flavonoids by High Performance Liquid Chromatography

    ERIC Educational Resources Information Center

    Freeman, Jessica D.; Niemeyer, Emily D.

    2008-01-01

    We have developed a laboratory experiment that uses high performance liquid chromatography (HPLC) to quantify flavonoid levels in a variety of commercial teas. Specifically, this experiment analyzes a group of flavonoids known as catechins, plant-derived polyphenolic compounds commonly found in many foods and beverages, including green and black…

  8. Quantitative determination of phenol by high-pressure liquid chromatography.

    PubMed

    Musto, J D; Sane, J N; Warner, V D

    1977-08-01

    High-pressure liquid chromatography was used with a 5-micrometer silica gel column to quantitate the phenol in phenolated calamine lotion USP and a commercial antiseptic solution. This method requires less than 10 min/assay, and other compounds present in the products analyzed did not interfere.

  9. Determination of Caffeine in Beverages by High Performance Liquid Chromatography.

    ERIC Educational Resources Information Center

    DiNunzio, James E.

    1985-01-01

    Describes the equipment, procedures, and results for the determination of caffeine in beverages by high performance liquid chromatography. The method is simple, fast, accurate, and, because sample preparation is minimal, it is well suited for use in a teaching laboratory. (JN)

  10. An Inexpensive Liquid Chromatography Apparatus for Undergraduate Teaching.

    ERIC Educational Resources Information Center

    McCamish, Malcolm; And Others

    1982-01-01

    Describes an inexpensive, low-pressure liquid chromatography pump, slurry filler, stainless steel columns, and injector system suitable for the undergraduate laboratory or routine analysis. Includes sectional diagram of the pump and construction diagram of the preparative columns. (Author/SK)

  11. LCEC: The Combination of Liquid Chromatography and Electrochemistry.

    ERIC Educational Resources Information Center

    Kissinger, Peter T.

    1983-01-01

    Use of combined liquid chromatography and finite-current electrochemistry (LCEC) procedures are discussed. Also discusses the relationship between electroactivity and molecular structure, selectivity in LCEC, and LCEC applications. Because of its selectivity and low detection limits, the procedures are most often applied in biomedical and…

  12. Mallow carotenoids determined by high-performance liquid chromatography

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mallow (corchorus olitorius) is a green vegetable, which is widely consumed either fresh or dry by Middle East population. This study was carried out to determine the contents of major carotenoids quantitatively in mallow, by using a High Performance Liquid Chromatography (HPLC) equipped with a Bis...

  13. Analysis of Whiskey by Dispersive Liquid-Liquid Microextraction Coupled with Gas Chromatography/Mass Spectrometry: An Upper Division Analytical Chemistry Experiment Guided by Green Chemistry

    ERIC Educational Resources Information Center

    Owens, Janel E.; Zimmerman, Laura B.; Gardner, Michael A.; Lowe, Luis E.

    2016-01-01

    Analysis of whiskey samples prepared by a green microextraction technique, dispersive liquid-liquid microextraction (DLLME), before analysis by a qualitative gas chromatography-mass spectrometry (GC/MS) method, is described as a laboratory experiment for an upper division instrumental methods of analysis laboratory course. Here, aroma compounds in…

  14. Sample injector for high pressure liquid chromatography

    DOEpatents

    Paul, Phillip H.; Arnold, Don W.; Neyer, David W.

    2001-01-01

    Apparatus and method for driving a sample, having a well-defined volume, under pressure into a chromatography column. A conventional high pressure sampling valve is replaced by a sample injector composed of a pair of injector components connected in series to a common junction. The injector components are containers of porous dielectric material constructed so as to provide for electroosmotic flow of a sample into the junction. At an appropriate time, a pressure pulse from a high pressure source, that can be an electrokinetic pump, connected to the common junction, drives a portion of the sample, whose size is determined by the dead volume of the common junction, into the chromatographic column for subsequent separation and analysis. The apparatus can be fabricated on a substrate for microanalytical applications.

  15. 21 CFR 862.2250 - Gas liquid chromatography system for clinical use.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Gas liquid chromatography system for clinical use... Instruments § 862.2250 Gas liquid chromatography system for clinical use. (a) Identification. A gas liquid chromatography system for clinical use is a device intended to separate one or more drugs or compounds from...

  16. 21 CFR 862.2250 - Gas liquid chromatography system for clinical use.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Gas liquid chromatography system for clinical use... Instruments § 862.2250 Gas liquid chromatography system for clinical use. (a) Identification. A gas liquid chromatography system for clinical use is a device intended to separate one or more drugs or compounds from...

  17. 21 CFR 862.2250 - Gas liquid chromatography system for clinical use.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Gas liquid chromatography system for clinical use... Instruments § 862.2250 Gas liquid chromatography system for clinical use. (a) Identification. A gas liquid chromatography system for clinical use is a device intended to separate one or more drugs or compounds from...

  18. 21 CFR 862.2250 - Gas liquid chromatography system for clinical use.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Gas liquid chromatography system for clinical use... Instruments § 862.2250 Gas liquid chromatography system for clinical use. (a) Identification. A gas liquid chromatography system for clinical use is a device intended to separate one or more drugs or compounds from...

  19. 21 CFR 862.2260 - High pressure liquid chromatography system for clinical use.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false High pressure liquid chromatography system for... Clinical Laboratory Instruments § 862.2260 High pressure liquid chromatography system for clinical use. (a) Identification. A high pressure liquid chromatography system for clinical use is a device intended to...

  20. 21 CFR 862.2250 - Gas liquid chromatography system for clinical use.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Gas liquid chromatography system for clinical use... Instruments § 862.2250 Gas liquid chromatography system for clinical use. (a) Identification. A gas liquid chromatography system for clinical use is a device intended to separate one or more drugs or compounds from...

  1. 21 CFR 862.2260 - High pressure liquid chromatography system for clinical use.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false High pressure liquid chromatography system for... Clinical Laboratory Instruments § 862.2260 High pressure liquid chromatography system for clinical use. (a) Identification. A high pressure liquid chromatography system for clinical use is a device intended to...

  2. 21 CFR 862.2260 - High pressure liquid chromatography system for clinical use.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false High pressure liquid chromatography system for... Clinical Laboratory Instruments § 862.2260 High pressure liquid chromatography system for clinical use. (a) Identification. A high pressure liquid chromatography system for clinical use is a device intended to...

  3. 21 CFR 862.2260 - High pressure liquid chromatography system for clinical use.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false High pressure liquid chromatography system for... Clinical Laboratory Instruments § 862.2260 High pressure liquid chromatography system for clinical use. (a) Identification. A high pressure liquid chromatography system for clinical use is a device intended to...

  4. 21 CFR 862.2260 - High pressure liquid chromatography system for clinical use.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false High pressure liquid chromatography system for... Clinical Laboratory Instruments § 862.2260 High pressure liquid chromatography system for clinical use. (a) Identification. A high pressure liquid chromatography system for clinical use is a device intended to...

  5. Exploring Fluorous Affinity by Liquid Chromatography.

    PubMed

    Catani, Martina; Guzzinati, Roberta; Marchetti, Nicola; Pasti, Luisa; Cavazzini, Alberto

    2015-07-01

    Terms such as "fluorous affinity" and "fluorophilicity" have been used to describe the unique partition and sorption properties often exhibited by highly fluorinated organic compounds, that is molecules rich in sp(3) carbon-fluorine bonds. In this work, we made use of a highly fluorinated stationary phase and a series of benzene derivatives to study the effect of one single perfluorinated carbon on the chromatographic behavior and adsorption properties of molecules. For this purpose, the adsorption equilibria of α,α,α-trifluorotoluene, toluene, and other alkylbenzenes have been studied by means of nonlinear chromatography in a variety of acetonitrile/water eluents. Our results reveal that one single perfluorinated carbon is already enough to induce a drastic change in the adsorption properties of molecules on the perfluorinated stationary phase. In particular, it has been found that adsorption is monolayer if the perfluoroalkyl carbon is present but that, when this unit is missing, molecules arrange as multilayer stack structures. These findings can contribute to the understanding of molecular mechanisms of fluorous affinity. PMID:26047527

  6. Optimizing heterosurface adsorbent synthesis for liquid chromatography

    NASA Astrophysics Data System (ADS)

    Bogoslovskii, S. Yu.; Serdan, A. A.

    2016-03-01

    The structural and geometric parameters of a silica matrix (SM) for the synthesis of heterosurface adsorbents (HAs) are optimized. Modification is performed by shielding the external surfaces of alkyl-modified silica (AS) using human serum albumin and its subsequent crosslinking. The structural and geometric characteristics of the SM, AS, and HA are measured via low-temperature nitrogen adsorption. It is found that the structural characteristics of AS pores with diameters D < 6 nm do not change during HA synthesis, while the volume of pores with diameters of 6 nm < D < 9 nm shrinks slightly due to the adsorption of albumin in the pore orifices. It is established that the volume of pores with diameters D > 9 nm reduces significantly due to adsorption of albumin. It is concluded that silica gel with a maximum pore size distribution close to 5 nm and a minimal proportion of pores with D > 9 nm is optimal for HA synthesis; this allows us to achieve the greatest similarity between the chromatographic retention parameters for HA and AS. The suitability of the synthesized adsorbents for analyzing drugs in biological fluids through direct sample injection is confirmed by chromatography. It was found that the percentage of the protein fraction detected at the outlet of the chromatographic column is 98%.

  7. The analysis of aqueous mixtures using liquid chromatography-electrospray mass spectrometry

    SciTech Connect

    Johnson, S.

    1999-02-12

    The focus of this dissertation is the use of chromatographic methods coupled with electrospray mass spectrometry (ES-MS) for the determination of both organic and inorganic compounds in aqueous solutions. The combination of liquid chromatography (LC) methods and ES-MS offers one of the foremost methods for determining compounds in complex aqueous solutions. In this work, LC-ES-MS methods are devised using ion exclusion chromatography, reversed phase chromatography, and ion exchange chromatography, as well as capillary electrophoresis (CE). For an aqueous sample, these LC-ES-MS and CE-ES-MS techniques require no sample preparation or analyte derivatization, which makes it possible to observe a wide variety of analytes as they exist in solution. The majority of this work focuses on the use of LC-ES-MS for the determination of unknown products and intermediates formed during electrochemical incineration (ECI), an experimental waste remediation process. This report contains a general introduction to the project and the general conclusions. Four chapters have been removed for separate processing. Titles are: Chapter 2: Determination of small carboxylic acids by ion exclusion chromatography with electrospray mass spectrometry; Chapter 3: Electrochemical incineration of benzoquinone in aqueous media using a quaternary metal oxide electrode in the absence of a soluble supporting electrolyte; Chapter 4: The determination of electrochemical incineration products of 4-chlorophenol by liquid chromatography-electrospray mass spectrometry; and Chapter 5: Determination of small carboxylic acids by capillary electrophoresis with electrospray mass spectrometry.

  8. Determination of febuxostat in human plasma using ultra-performance liquid chromatography tandem mass spectrometry.

    PubMed

    Lukram, Ojikumar; Parmar, Shivaji; Hande, Amit

    2013-06-01

    A rapid and sensitive liquid chromatography-tandem mass spectrometry method has been developed and validated for the determination of febuxostat in human plasma. The liquid-liquid extraction technique was used for the extraction of febuxostat from human plasma using trandolapril as the internal standard (IS). Chromatography was performed on a ultra-performance liquid chromatography (UPLC) BEH C18, 50 mm X 2.1 mm, 1.7 µm particle size column, with the mobile phase consisting of 0.1% formic acid and acetonitrile (in a 25:75 ratio), followed by detection using mass spectrometry. The method involves a simple reversed isocratic chromatography condition and mass spectrometry detection, which enables detection at sub-microgram levels. The method was validated and the lower limit of quantification for febuxostat was found to be 0.075 µg/ml. The mean recovery for febuxostat ranged from 100.9 to 106.5%. This method increased the sensitivity and selectivity; resulting in high-throughput analysis of febuxostat using commercially available IS for pharmacokinetic, bioavailability, and bioequivalence studies, with a chromatographic run time of 1.5 min only.

  9. Standard Flow Liquid Chromatography for Shotgun Proteomics in Bioenergy Research

    PubMed Central

    González Fernández-Niño, Susana M.; Smith-Moritz, A. Michelle; Chan, Leanne Jade G.; Adams, Paul D.; Heazlewood, Joshua L.; Petzold, Christopher J.

    2015-01-01

    Over the past 10 years, the bioenergy field has realized significant achievements that have encouraged many follow on efforts centered on biosynthetic production of fuel-like compounds. Key to the success of these efforts has been transformational developments in feedstock characterization and metabolic engineering of biofuel-producing microbes. Lagging far behind these advancements are analytical methods to characterize and quantify systems of interest to the bioenergy field. In particular, the utilization of proteomics, while valuable for identifying novel enzymes and diagnosing problems associated with biofuel-producing microbes, is limited by a lack of robustness and limited throughput. Nano-flow liquid chromatography coupled to high-mass accuracy, high-resolution mass spectrometers has become the dominant approach for the analysis of complex proteomic samples, yet such assays still require dedicated experts for data acquisition, analysis, and instrument upkeep. The recent adoption of standard flow chromatography (ca. 0.5 mL/min) for targeted proteomics has highlighted the robust nature and increased throughput of this approach for sample analysis. Consequently, we assessed the applicability of standard flow liquid chromatography for shotgun proteomics using samples from Escherichia coli and Arabidopsis thaliana, organisms commonly used as model systems for lignocellulosic biofuels research. Employing 120 min gradients with standard flow chromatography, we were able to routinely identify nearly 800 proteins from E. coli samples; while for samples from Arabidopsis, over 1,000 proteins could be reliably identified. An examination of identified peptides indicated that the method was suitable for reproducible applications in shotgun proteomics. Standard flow liquid chromatography for shotgun proteomics provides a robust approach for the analysis of complex samples. To the best of our knowledge, this study represents the first attempt to validate the standard

  10. Standard flow liquid chromatography for shotgun proteomics in bioenergy research.

    PubMed

    González Fernández-Niño, Susana M; Smith-Moritz, A Michelle; Chan, Leanne Jade G; Adams, Paul D; Heazlewood, Joshua L; Petzold, Christopher J

    2015-01-01

    Over the past 10 years, the bioenergy field has realized significant achievements that have encouraged many follow on efforts centered on biosynthetic production of fuel-like compounds. Key to the success of these efforts has been transformational developments in feedstock characterization and metabolic engineering of biofuel-producing microbes. Lagging far behind these advancements are analytical methods to characterize and quantify systems of interest to the bioenergy field. In particular, the utilization of proteomics, while valuable for identifying novel enzymes and diagnosing problems associated with biofuel-producing microbes, is limited by a lack of robustness and limited throughput. Nano-flow liquid chromatography coupled to high-mass accuracy, high-resolution mass spectrometers has become the dominant approach for the analysis of complex proteomic samples, yet such assays still require dedicated experts for data acquisition, analysis, and instrument upkeep. The recent adoption of standard flow chromatography (ca. 0.5 mL/min) for targeted proteomics has highlighted the robust nature and increased throughput of this approach for sample analysis. Consequently, we assessed the applicability of standard flow liquid chromatography for shotgun proteomics using samples from Escherichia coli and Arabidopsis thaliana, organisms commonly used as model systems for lignocellulosic biofuels research. Employing 120 min gradients with standard flow chromatography, we were able to routinely identify nearly 800 proteins from E. coli samples; while for samples from Arabidopsis, over 1,000 proteins could be reliably identified. An examination of identified peptides indicated that the method was suitable for reproducible applications in shotgun proteomics. Standard flow liquid chromatography for shotgun proteomics provides a robust approach for the analysis of complex samples. To the best of our knowledge, this study represents the first attempt to validate the standard

  11. Thin-layer chromatography-densitometry and liquid chromatography analysis of alkaloids in leaves of Papaver somniferum under stress conditions.

    PubMed

    Szabó, Beata; Lakatos, Agnes; Kõszegi, Tamás; Kátay, György; Botz, L

    2005-01-01

    The effect of stress conditions on the concentrations of secondary metabolites were examined during various developmental stages of Papaver somniferum plants. P. somniferum plants were grown in laboratory conditions (Budakalász). The experiment consisted of 22 treatments. Significantly different alkaloid contents can be observed under different stress conditions. In general, the alkaloid contents of plants are very low; therefore, a highly sensitive and reliable method has to be developed for analysis. The amount of alkaloids was measured by 2 separation and detection techniques. Accuracy of the thin-layer chromatography method for quantitative analysis is limited. Without purification of samples the background is too noisy. Column liquid chromatography is a sensitive and relatively inexpensive method that allows precise quantitative determination of the alkaloid content.

  12. An electrostatic precipitator for preparative gas-liquid chromatography.

    PubMed

    Borka, L; Privett, O S

    1966-03-01

    The effect of the operating variables of electrostatic precipitators on the recovery and structure of methyl esters and related aerosol forming compounds collected in preparative gas-liquid chromatography was studied.Aerosol formation was prevented by AC or DC voltages of 5000 to 12000 volts. AC was more effective than DC but caused changes in structure which were detectable by both thin-layer and gas-liquid chromatographic methods of analysis.An apparatus of simple construction and operation was designed for the collection of methyl esters and its use demonstrated with several model compounds.

  13. Determination of serotonin released from coffee wax by liquid chromatography.

    PubMed

    Kele, M; Ohmacht, R

    1996-04-12

    A simple hydrolysis and extraction method was developed for the release of serotonin (5-hydroxytryptamine) from a coffee wax sample obtained from decaffeination of coffee beans. The recoverable amount of serotonin was determined by reversed-phase high-performance liquid chromatography with gradient elution and UV detection, using the standard addition method. Different type of basic deactivated chromatographic columns were used for the separation.

  14. Nitrogen-sensitive thermionic detection in microcolumn liquid chromatography.

    PubMed

    Gluckman, J C; Novotny, M

    1985-10-01

    The dual-flame thermionic detector for microcolumn liquid chromatography has been improved and optimized for nitrogen sensitivity. The total column effluent is concentrically nebulized and aspirated directly into an air-hydrogen diffusion flame, while detection limits of 1.4 X 10(-11) g nitrogen/sec at the maximum of a Gaussian peak are achieved. Detection linearity spans three orders of magnitude. An example of the analysis of underivatized barbiturate standards is provided.

  15. Determination of serotonin released from coffee wax by liquid chromatography.

    PubMed

    Kele, M; Ohmacht, R

    1996-04-12

    A simple hydrolysis and extraction method was developed for the release of serotonin (5-hydroxytryptamine) from a coffee wax sample obtained from decaffeination of coffee beans. The recoverable amount of serotonin was determined by reversed-phase high-performance liquid chromatography with gradient elution and UV detection, using the standard addition method. Different type of basic deactivated chromatographic columns were used for the separation. PMID:8680597

  16. Principles and Applications of Liquid Chromatography-Mass Spectrometry in Clinical Biochemistry

    PubMed Central

    Pitt, James J

    2009-01-01

    Liquid chromatography-mass spectrometry (LC-MS) is now a routine technique with the development of electrospray ionisation (ESI) providing a simple and robust interface. It can be applied to a wide range of biological molecules and the use of tandem MS and stable isotope internal standards allows highly sensitive and accurate assays to be developed although some method optimisation is required to minimise ion suppression effects. Fast scanning speeds allow a high degree of multiplexing and many compounds can be measured in a single analytical run. With the development of more affordable and reliable instruments, LC-MS is starting to play an important role in several areas of clinical biochemistry and compete with conventional liquid chromatography and other techniques such as immunoassay. PMID:19224008

  17. [PMIM]Br@TiO2 nanocomposite reinforced hollow fiber solid/liquid phase microextraction: an effective extraction technique for measurement of benzodiazepines in hair, urine and wastewater samples combined with high-performance liquid chromatography.

    PubMed

    Es'haghi, Zarrin; Nezhadali, Azizollah; Bahar, Shahriyar; Bohlooli, Shahab; Banaei, Alireza

    2015-02-01

    A new design of hollow fiber solid-liquid phase microextraction (HF-SLPME) was developed for the determination of benzodiazepines (BZPs) in hair, urine and wastewater. The membrane extraction with 1-pentyl-3-methylimidazolium bromide coated titanium dioxide ([PMIM]Br@TiO2) sorbent used in this research is a two-phase supported membrane extraction consisting of an aqueous (donor phase), and n-octanol/nano [PMIM]Br@TiO2 (acceptor phase) system operated in direct immersion sampling mode. The 1-pentyl-3-methylimidazolium bromide (ionic liquid) coated nano TiO2 dispersed in the organic solvent (n-octanol) is held into a porous membrane supported by capillary forces and sonification. It is in contact with the feed phase, which is the aqueous sample. The experimental setup is very simple and highly affordable. The hollow fiber is disposable, so single use of the fiber reduces the risk of cross-contamination and carry-over problems. The proposed method allows the very effective and enriched recuperation of BZPs into one single extract. In order to obtain high extraction efficiency of the analytes using this novel sorbent, the main parameters were optimized. Under the optimized extraction conditions, the method showed good linearity (0.05-6000ngmL(-1)), low limits of detection (0.08-0.5ngmL(-1)) and good enrichment (533-1190).

  18. [PMIM]Br@TiO2 nanocomposite reinforced hollow fiber solid/liquid phase microextraction: an effective extraction technique for measurement of benzodiazepines in hair, urine and wastewater samples combined with high-performance liquid chromatography.

    PubMed

    Es'haghi, Zarrin; Nezhadali, Azizollah; Bahar, Shahriyar; Bohlooli, Shahab; Banaei, Alireza

    2015-02-01

    A new design of hollow fiber solid-liquid phase microextraction (HF-SLPME) was developed for the determination of benzodiazepines (BZPs) in hair, urine and wastewater. The membrane extraction with 1-pentyl-3-methylimidazolium bromide coated titanium dioxide ([PMIM]Br@TiO2) sorbent used in this research is a two-phase supported membrane extraction consisting of an aqueous (donor phase), and n-octanol/nano [PMIM]Br@TiO2 (acceptor phase) system operated in direct immersion sampling mode. The 1-pentyl-3-methylimidazolium bromide (ionic liquid) coated nano TiO2 dispersed in the organic solvent (n-octanol) is held into a porous membrane supported by capillary forces and sonification. It is in contact with the feed phase, which is the aqueous sample. The experimental setup is very simple and highly affordable. The hollow fiber is disposable, so single use of the fiber reduces the risk of cross-contamination and carry-over problems. The proposed method allows the very effective and enriched recuperation of BZPs into one single extract. In order to obtain high extraction efficiency of the analytes using this novel sorbent, the main parameters were optimized. Under the optimized extraction conditions, the method showed good linearity (0.05-6000ngmL(-1)), low limits of detection (0.08-0.5ngmL(-1)) and good enrichment (533-1190). PMID:25589255

  19. RECENT ADVANCES IN ULTRA-HIGH PERFORMANCE LIQUID CHROMATOGRAPHY FOR THE ANALYSIS OF TRADITIONAL CHINESE MEDICINE.

    PubMed

    Huang, Huilian; Liu, Min; Chen, Pei

    2014-01-01

    Traditional Chinese medicine has been widely used for the prevention and treatment of various diseases for thousands of years in China. Ultra-high performance liquid chromatography (UHPLC) is a relatively new technique offering new possibilities. This paper reviews recent developments in UHPLC in the separation and identification, fingerprinting, quantification, and metabolism of traditional Chinese medicine. Recently, the combination of UHPLC with MS has improved the efficiency of the analysis of these materials.

  20. RECENT ADVANCES IN ULTRA-HIGH PERFORMANCE LIQUID CHROMATOGRAPHY FOR THE ANALYSIS OF TRADITIONAL CHINESE MEDICINE

    PubMed Central

    Huang, Huilian; Liu, Min; Chen, Pei

    2014-01-01

    Traditional Chinese medicine has been widely used for the prevention and treatment of various diseases for thousands of years in China. Ultra-high performance liquid chromatography (UHPLC) is a relatively new technique offering new possibilities. This paper reviews recent developments in UHPLC in the separation and identification, fingerprinting, quantification, and metabolism of traditional Chinese medicine. Recently, the combination of UHPLC with MS has improved the efficiency of the analysis of these materials. PMID:25045170

  1. Exploring Liquid Sequential Injection Chromatography to Teach Fundamentals of Separation Methods: A Very Fast Analytical Chemistry Experiment

    ERIC Educational Resources Information Center

    Penteado, Jose C.; Masini, Jorge Cesar

    2011-01-01

    Influence of the solvent strength determined by the addition of a mobile-phase organic modifier and pH on chromatographic separation of sorbic acid and vanillin has been investigated by the relatively new technique, liquid sequential injection chromatography (SIC). This technique uses reversed-phase monolithic stationary phase to execute fast…

  2. Microporous membrane liquid-liquid extraction coupled on-line with normal-phase liquid chromatography for the determination of cationic surfactants in river and waste water.

    PubMed

    Norberg, J; Thordarson, E; Mathiasson, L; Jönsson, J A

    2000-02-11

    Membrane-based continuous liquid-liquid extraction combined on-line with normal-phase liquid chromatography is proposed for the determination of cationic surfactants in complex aqueous samples. The technique has the potential for complete automation. Selective enrichment of cationic surfactants from spiked river water and waste-water samples with simultaneous removal of matrix constituents, followed by a quantitative transfer of the extract onto a liquid chromatographic column and separation of the surfactant homologues yielding low detection limits, has been realised. The homologues of alkyldimethylbenzylammonium chloride (Dodigen 226) were chosen as model compounds in the method development. Dodigen homologues were ion-paired with heptanoic acid and extracted into chlorobutane by means of microporous membrane liquid-liquid extraction. It was thereby possible to attain an enrichment of over 250 times for one of the homologues, viz. the concentration in the organic liquid is 250 times higher than in the original sample. Detection limits for the three best-detected homologues of the mixture were in the range 0.7-5 microg/l in spiked river water samples. Ion-pair normal-phase liquid chromatography, again with heptanoic acid as counter-ion, gave the necessary separation of the surfactant homologues.

  3. A solid phase microextraction coating based on ionic liquid sol-gel technique for determination of benzene, toluene, ethylbenzene and o-xylene in water samples using gas chromatography flame ionization detector.

    PubMed

    Sarafraz-Yazdi, Ali; Vatani, Hossein

    2013-07-26

    Ionic liquid mediated sol-gel sorbents for head-space solid phase microextraction (HS-SPME) were developed for the extraction of benzene, toluene, ethylbenzene and o-xylene (BTEX) compounds from water samples in ultra-trace levels. The analytes were subsequently analyzed with gas chromatography coupled to flame ionization detector (GC-FID). Three different coating fibers were prepared including: poly(dimethylsiloxane) (PDMS), coating prepared from poly(dimethylsiloxane) in the presence of ionic liquid as co-solvent and conditioned at a higher temperature than decomposition temperature of ionic liquid (PDMS-IL-HT) and coating prepared from poly(dimethylsiloxane) in the presence of ionic liquid as co-solvent and conditioned at a lower temperature than decomposition temperature of ionic liquid (PDMS-IL-LT). Prepared fibers demonstrate many advantages such as high thermal and chemical stabilities due to the chemical bonding of the coatings with the silanol groups on the fused-silica surface fiber. These fibers have shown long life time up to 180 extractions. The scanning electron micrographs of the fibers surfaces revealed that addition of ionic liquid into the sol solution during the sol-gel process increases the fiber coating thickness, affects the form of fiber structure and also leaves high pores in the fiber surface that cause high surface area and therefore increases sample capacity of the fibers. The important parameters that affect the extraction efficiency are desorption temperature and time, sample volume, extraction temperature, extraction time, stirring speed and salt effect. Therefore these factors were investigated and optimized. Under optimal conditions, the dynamic linear range with PDMS-IL-HT, PDMS and PDMS-IL-LT fibers were 0.3-200,000; 50-200,000 and 170-150,000pgmL(-1) and the detection limits (S/N=3) were 0.1-2 and 15-200 and 50-500pgmL(-1), and limit of quantifications (S/N=10) were 0.3-8 and 50-700 and 170-1800, respectively. The relative

  4. Characterization of goat colostrum oligosaccharides by nano-liquid chromatography on chip quadrupole time-of-flight mass spectrometry and hydrophilic interaction liquid chromatography-quadrupole mass spectrometry.

    PubMed

    Martín-Ortiz, A; Salcedo, J; Barile, D; Bunyatratchata, A; Moreno, F J; Martin-García, I; Clemente, A; Sanz, M L; Ruiz-Matute, A I

    2016-01-01

    A detailed qualitative and quantitative characterization of goat colostrum oligosaccharides (GCO) has been carried out for the first time. Defatted and deproteinized colostrum samples, previously treated by size exclusion chromatography (SEC) to remove lactose, were analyzed by nanoflow liquid chromatography-quadrupole-time of flight mass spectrometry (Nano-LC-Chip-Q-TOF MS). Up to 78 oligosaccharides containing hexose, hexosamine, fucose, N-acetylneuraminic acid or N-glycolylneuraminic acid monomeric units were identified in the samples, some of them detected for the first time in goat colostra. As a second step, a hydrophilic interaction liquid chromatography coupled to mass spectrometry (HILIC-MS) methodology was developed for the separation and quantitation of the main GCO, both acidic and neutral carbohydrates. Among other experimental chromatographic conditions, mobile phase additives and column temperature were evaluated in terms of retention time, resolution, peak width and symmetry of target carbohydrates. Narrow peaks (wh: 0.2-0.6min) and good symmetry (As: 0.8-1.4) were obtained for GCO using an acetonitrile:water gradient with 0.1% ammonium hydroxide at 40°C. These conditions were selected to quantify the main oligosaccharides in goat colostrum samples. Values ranging from 140 to 315mgL(-1) for neutral oligosaccharides and from 83 to 251mgL(-1) for acidic oligosaccharides were found. The combination of both techniques resulted to be useful to achieve a comprehensive characterization of GCO.

  5. Characterization of goat colostrum oligosaccharides by nano-liquid chromatography on chip quadrupole time-of-flight mass spectrometry and hydrophilic interaction liquid chromatography-quadrupole mass spectrometry

    PubMed Central

    Martín-Ortiz, A.; Salcedo, J.; Barile, D.; Bunyatratchata, A.; Moreno, F.J.; Martin-García, I.; Clemente, A.; Sanz, M.L.; Ruiz-Matute, A.I.

    2016-01-01

    A detailed qualitative and quantitative characterization of goat colostrum oligosaccharides (GCO) has been carried out for the first time. Defatted and deproteinized colostrum samples, previously treated by size exclusion chromatography (SEC) to remove lactose, were analyzed by nanoflow liquid chromatography-quadrupole-time of flight mass spectrometry (Nano-LC-Chip-Q-TOF MS). Up to 78 oligosaccharides containing hexose, hexosamine, fucose, N-acetylneuraminic acid or N-glycolylneuraminic acid monomeric units were identified in the samples, some of them detected for the first time in goat colostra. As a second step, a hydrophilic interaction liquid chromatography coupled to mass spectrometry (HILIC-MS) methodology was developed for the separation and quantitation of the main GCO, both acidic and neutral carbohydrates. Among other experimental chromatographic conditions, mobile phase additives and column temperature were evaluated in terms of retention time, resolution, peak width and symmetry of target carbohydrates. Narrow peaks (wh: 0.2–0.6 min) and good symmetry (As: 0.8–1.4) were obtained for GCO using an acetonitrile:water gradient with 0.1% ammonium hydroxide at 40 °C. These conditions were selected to quantify the main oligosaccharides in goat colostrum samples. Values ranging from 140 to 315 mg L−1 for neutral oligosaccharides and from 83 to 251 mg L−1 for acidic oligosaccharides were found. The combination of both techniques resulted to be useful to achieve a comprehensive characterization of GCO. PMID:26427327

  6. Phase comparison technique for measuring liquid-liquid phase equilibrium

    NASA Astrophysics Data System (ADS)

    Lu, Z.; Daridon, J. L.; Lagourette, B.; Ye, S.

    1999-04-01

    In this article, a new method is demonstrated to measure the liquid-liquid phase equilibrium for binary systems. A phase comparison technique was employed to real-time display the phase-time curve in a "wave form (time) object" of Hewlett-Packard visual engineering environment. It was found that the phase-time curve showed a distorted wave form when liquid-liquid phase transition took place. The abnormal curve can therefore be used to detect liquid-liquid phase transitions. Measurements were performed in several binary systems such as nitromethane+1-hexanol, nitromethane+butanol, and nitroethane+n-hexane. The experimental results are in good agreement with those in the literature.

  7. Mass transfer mechanism in chiral reversed phase liquid chromatography.

    PubMed

    Gritti, Fabrice; Guiochon, Georges

    2014-03-01

    The mechanism of mass transfer in chiral chromatography was investigated using an experimental protocol already applied in RPLC and HILIC chromatography. The different contributions to the reduced height equivalent to a theoretical plate (HETP) include the longitudinal diffusion HETP term, the solid-liquid mass transfer resistance HETP term, the short-range eddy dispersion HETP term, and the long-range eddy dispersion HETP term. Their accurate measurement permits the determination of the adsorption rate constant kads of trans-stilbene enantiomers on a column packed with Lux 5 μm Cellulose-1 particles. The experimental results demonstrate that the number of adsorption-desorption steps per unit time of chiral compounds on polysaccharide-based chiral stationary phases is four orders of magnitude smaller than that of achiral compounds.

  8. Emerging liquid chromatography-mass spectrometry technologies improving dried blood spot analysis.

    PubMed

    Rao, Ramisetti Nageswara

    2014-08-01

    Dried blood spots (DBS), a micro blood sampling technique, has recently gained interest in drug discovery and development due to its inherent advantages over the conventional whole blood, plasma or serum sample collection. Since the regulatory authorities have agreed to the use of blood as an acceptable biological matrix for drug exposure measurements, its applications have been extended not only to therapeutic drug monitoring but also to toxicokinetic and pharmacokinetic studies. The pharmaceutical industry is keen to promote DBS as a prominent tool in bioanalytical applications due to the financial, ethical and organizational issues involved in clinical trials. This could be accomplished due to the latest advances in modern analytical technology, particularly liquid chromatography-mass spectrometry. The present review discusses some of the emerging liquid chromatography-mass spectrometry technologies in improving DBS analysis for its innovative applications in the development of new drugs.

  9. Analysis of radioactive mixed hazardous waste using derivatization gas chromatography/mass spectrometry, liquid chromatography, and liquid chromatography/mass spectrometry

    SciTech Connect

    Campbell, J.A.; Lerner, B.D.; Bean, R.M.; Grant, K.E.; Lucke, R.B.; Mong, G.M.; Clauss, S.A.

    1994-08-01

    Six samples of core segments from Tank 101-SY were analyzed for chelators, chelator fragments, and several carboxylic acids by derivatization gas chromatography/mass spectrometry. The major components detected were ethylenediaminetetraacetic acid, nitroso-iminodiacetic acid, nitrilotriacetic acid, citric acid, succinic acid, and ethylenediaminetriacetic acid. The chelator of highest concentration was ethylenediaminetetraacetic acid in all six samples analyzed. Liquid chromatography was used to quantitate low molecular weight acids including oxalic, formic, glycolic, and acetic acids, which are present in the waste as acid salts. From 23 to 61% of the total organic carbon in the samples analyzed was accounted for by these acids.

  10. Gas chromatography on wall-coated open-tubular columns with ionic liquid stationary phases.

    PubMed

    Poole, Colin F; Lenca, Nicole

    2014-08-29

    Ionic liquids have moved from novel to practical stationary phases for gas chromatography with an increasing portfolio of applications. Ionic liquids complement conventional stationary phases because of a combination of thermophysical and solvation properties that only exist for ionic solvents. Their high thermal stability and low vapor pressure makes them suitable as polar stationary phases for separations requiring high temperatures. Ionic liquids are good solvents and can be used to expand the chemical space for separations. They are the only stationary phases with significant hydrogen-bond acidity in common use; they extend the hydrogen-bond basicity of conventional stationary phases; they are as dipolar/polarizable as the most polar conventional stationary phases; and some ionic liquids are significantly less cohesive than conventional polar stationary phases. Problems in column coating techniques and related low column performance, column activity, and stationary phase reactivity require further exploration as the reasons for these features are poorly understood at present.

  11. Modeling of closed-loop recycling liquid-liquid chromatography: Analytical solutions and model analysis.

    PubMed

    Kostanyan, Artak E

    2015-08-01

    In closed-loop recycling (CLR) chromatography, the effluent from the outlet of a column is directly returned into the column through the sample feed line and continuously recycled until the required separation is reached. To select optimal operating conditions for the separation of a given feed mixture, an appropriate mathematical description of the process is required. This work is concerned with the analysis of models for the CLR separations. Due to the effect of counteracting mechanisms on separation of solutes, analytical solutions of the models could be helpful to understand and optimize chromatographic processes. The objective of this work was to develop analytical expressions to describe the CLR counter-current (liquid-liquid) chromatography (CCC). The equilibrium dispersion and cell models were used to describe the transport and separation of solutes inside a CLR CCC column. The Laplace transformation is applied to solve the model equations. Several possible CLR chromatography methods for the binary and complex mixture separations are simulated.

  12. Separation of sulfoalkylated cyclodextrins with hydrophilic interaction liquid chromatography.

    PubMed

    Jaramillo, Michael; Kirschner, Daniel L; Dai, Zhipeng; Green, Thomas K

    2013-11-01

    Determination of the charged state distributions of partially- and fully-substituted sulfoalkylated cyclodextrins was achieved using hydrophilic interaction liquid chromatography (HILIC). HILIC analysis of a spiked sample of the partially sulfopropylated cyclodextrins was achieved using a gradient to baseline resolve the charged states from -1 to -14. The fully-substituted CDs yielded a major peak with some trace impurities and the partially-substituted sulfopropylated cyclodextrins showed a wide range of charge states present in the mixture. Small changes in the structure of the cyclodextrins have a significant impact on the retention times of the various types of cyclodextrins investigated.

  13. Gas-liquid chromatography in lunar organic analysis.

    NASA Technical Reports Server (NTRS)

    Gehrke, C. W.

    1972-01-01

    Gas-liquid chromatography (GLC) is a powerful and sensitive method for the separation and detection of organic compounds at nanogram levels. The primary requirement for successful analyses is that the compounds of interest must be volatile under the chromatographic conditions employed. Nonvolatile organic compounds must be converted to volatile derivatives prior to analysis. The derivatives of choice must be both amenable to chromatographic separation and be relatively stable. The condition of volatility necessitates the development of efficient derivatization reactions for important groups of compounds as amino acids, carbohydrates, nucleosides, etc. Trimethylsilylation and trifluoroacetylation represent specific areas of recent prominence. Some relevant practical aspects of GLC are discussed.

  14. Size distributions of gold nanoclusters studied by liquid chromatography

    SciTech Connect

    WILCOXON,JESS P.; MARTIN,JAMES E.; PROVENCIO,PAULA P.

    2000-05-23

    The authors report high pressure liquid chromatography, (HPLC), and transmission electron microscopy, (TEM), studies of the size distributions of nanosize gold clusters dispersed in organic solvents. These metal clusters are synthesized in inverse micelles at room temperature and those investigated range in diameter from 1--10 nm. HPLC is sensitive enough to discern changes in hydrodynamic volume corresponding to only 2 carbon atoms of the passivating agent or metal core size changes of less than 4 {angstrom}. The authors have determined for the first time how the total cluster volume (metal core + passivating organic shell) changes with the size of the passivating agent.

  15. A novel amide stationary phase for hydrophilic interaction liquid chromatography and ion chromatography.

    PubMed

    Shen, Guobin; Zhang, Feifang; Yang, Bingcheng; Chu, Changhu; Liang, Xinmiao

    2013-10-15

    A novel amide stationary phase (ASP) for hydrophilic interaction liquid chromatography (HILIC) has been prepared via the Click chemistry method. It was based on the strategy that the amino group of Asparagine was easily transferred to the corresponding azido group and then clicked onto terminal alkyne-silica gel in the presence of Cu(I)-based catalyst. For the tested polar compounds including nucleosides and nucleic acid bases, ASP-based column has demonstrated good performance in terms of separation efficiency and column stability, and the retention mechanism was found to match well the typical HILIC retention. In addition, the ASP described here showed much better selectivity in separation of inorganic anions under ion chromatography mode relative to other kinds of commercial ASP.

  16. A novel amide stationary phase for hydrophilic interaction liquid chromatography and ion chromatography.

    PubMed

    Shen, Guobin; Zhang, Feifang; Yang, Bingcheng; Chu, Changhu; Liang, Xinmiao

    2013-10-15

    A novel amide stationary phase (ASP) for hydrophilic interaction liquid chromatography (HILIC) has been prepared via the Click chemistry method. It was based on the strategy that the amino group of Asparagine was easily transferred to the corresponding azido group and then clicked onto terminal alkyne-silica gel in the presence of Cu(I)-based catalyst. For the tested polar compounds including nucleosides and nucleic acid bases, ASP-based column has demonstrated good performance in terms of separation efficiency and column stability, and the retention mechanism was found to match well the typical HILIC retention. In addition, the ASP described here showed much better selectivity in separation of inorganic anions under ion chromatography mode relative to other kinds of commercial ASP. PMID:24054569

  17. Hyphenated and comprehensive liquid chromatography × gas chromatography-mass spectrometry for the identification of Mycobacterium tuberculosis.

    PubMed

    Mourão, Marta P B; Denekamp, Ilse; Kuijper, Sjoukje; Kolk, Arend H J; Janssen, Hans-Gerd

    2016-03-25

    Tuberculosis is one of the world's most emerging public health problems, particularly in developing countries. Chromatography based methods have been used to tackle this epidemic by focusing on biomarker detection. Unfortunately, interferences from lipids in the sputum matrix, particularly cholesterol, adversely affect the identification and detection of the marker compounds. The present contribution describes the serial combination of normal phase liquid chromatography (NPLC) with thermally assisted hydrolysis and methylation followed by gas chromatography-mass spectrometry (THM-GC-MS) to overcome the difficulties of biomarker evaluation. The in-series combination consists of an LC analysis where fractions are collected and then transferred to the THM-GC-MS system. This was either done with comprehensive coupling, transferring all the fractions, or with hyphenated interfacing, i.e. off-line multi heart-cutting, transferring only selected fractions. Owing to the high sensitivity and selectivity of LC as a sample pre-treatment method, and to the high specificity of the MS as a detector, this analytical approach, NPLC × THM-GC-MS, is extremely sensitive. The results obtained indicate that this analytical set-up is able to detect down to 1 × 10(3) mycobacteria/mL of Mycobacterium tuberculosis strain 124, spiked in blank sputum samples. It is a powerful analytical tool and also has great potential for full automation. If further studies demonstrate its usefulness when applied blind in real sputum specimens, this technique could compete with the current smear microscopy in the early diagnosis of tuberculosis.

  18. Chiral separation of pharmaceutical compounds using electrochemically modulated liquid chromatography (EMLC)

    SciTech Connect

    Wang, S.

    1999-02-12

    This research explores the application of a new technique, termed electrochemically modulated liquid chromatography (EMLC), to the chiral separations of pharmaceutical compounds. The introduction section provides a literature review of the technique and its applications, as well as brief overview of the research described in each of the next two chapters. Chapter 2 investigates the EMLC-based enantiomeric separation of a group of chiral benzodiazepines with {beta}-cyclodextrin as a chiral mobile phase additive. Chapter 3 demonstrates the effects of several experimental parameters on the separation efficiency of drug enantiomers. The author concludes with a general summary and possible directions for future studies. Chapters 2 and 3 are processed separately.

  19. Differentiation of mint (Mentha haplocalyx Briq.) from different regions in China using gas and liquid chromatography.

    PubMed

    Dong, Wenjiang; Ni, Yongnian; Kokot, Serge

    2015-02-01

    In this study, complex substances such as Mint (Mentha haplocalyx Briq.) samples from different growing regions in China were analyzed for phenolic compounds by high-performance liquid chromatography with diode array detection and for the volatile aroma compounds by gas chromatography with mass spectrometry. Chemometrics methods, e.g. principal component analysis, back-propagation artificial neural networks, and partial least squares discriminant analysis, were applied to resolve complex chromatographic profiles of Mint samples. A total of 49 aroma components and 23 phenolic compounds were identified in 79 Mint samples. Principal component analysis score plots from gas chromatography with mass spectrometry and high-performance liquid chromatography with diode array detection data sets showed a clear distinction among Mint from three different regions in China. Classification results showed that satisfactory performance of prediction ability for back-propagation artificial neural networks and partial least squares discriminant analysis. The major compounds that contributed to the discrimination were chlorogenic acid, unknown 3, kaempherol 7-O-rutinoside, salvianolic acid L, hesperidin, diosmetin, unknown 6 and pebrellin in Mint according to regression coefficients of the partial least squares discriminant analysis model. This study indicated that the proposed strategy could provide a simple and rapid technique to distinguish clearly complex profiles from samples such as Mint.

  20. Differentiation of mint (Mentha haplocalyx Briq.) from different regions in China using gas and liquid chromatography.

    PubMed

    Dong, Wenjiang; Ni, Yongnian; Kokot, Serge

    2015-02-01

    In this study, complex substances such as Mint (Mentha haplocalyx Briq.) samples from different growing regions in China were analyzed for phenolic compounds by high-performance liquid chromatography with diode array detection and for the volatile aroma compounds by gas chromatography with mass spectrometry. Chemometrics methods, e.g. principal component analysis, back-propagation artificial neural networks, and partial least squares discriminant analysis, were applied to resolve complex chromatographic profiles of Mint samples. A total of 49 aroma components and 23 phenolic compounds were identified in 79 Mint samples. Principal component analysis score plots from gas chromatography with mass spectrometry and high-performance liquid chromatography with diode array detection data sets showed a clear distinction among Mint from three different regions in China. Classification results showed that satisfactory performance of prediction ability for back-propagation artificial neural networks and partial least squares discriminant analysis. The major compounds that contributed to the discrimination were chlorogenic acid, unknown 3, kaempherol 7-O-rutinoside, salvianolic acid L, hesperidin, diosmetin, unknown 6 and pebrellin in Mint according to regression coefficients of the partial least squares discriminant analysis model. This study indicated that the proposed strategy could provide a simple and rapid technique to distinguish clearly complex profiles from samples such as Mint. PMID:25431171

  1. Fiber-based monolithic columns for liquid chromatography.

    PubMed

    Ladisch, Michael; Zhang, Leyu

    2016-10-01

    Fiber-based monoliths for use in liquid chromatographic separations are defined by columns packed with aligned fibers, woven matrices, or contiguous fiber structures capable of achieving rapid separations of proteins, macromolecules, and low molecular weight components. A common denominator and motivating driver for this approach, first initiated 25 years ago, was reducing the cost of bioseparations in a manner that also reduced residence time of retained components while achieving a high ratio of mass to momentum transfer. This type of medium, when packed into a liquid chromatography column, minimized the fraction of stagnant liquid and resulted in a constant plate height for non-adsorbing species. The uncoupling of dispersion from eluent flow rate enabled the surface chemistry of the stationary phase to be considered separately from fluid transport phenomena and pointed to new ways to apply chemistry for the engineering of rapid bioseparations. This paper addresses developments and current research on fiber-based monoliths and explains how the various forms of this type of chromatographic stationary phase have potential to provide new tools for analytical and preparative scale separations. The different stationary phases are discussed, and a model that captures the observed constant plate height as a function of mobile phase velocity is reviewed. Methods that enable hydrodynamically stable fiber columns to be packed and operated over a range of mobile phase flow rates, together with the development of new fiber chemistries, are shown to provide columns that extend the versatility of liquid chromatography using monoliths, particularly at the preparative scale. Graphical Abstract Schematic representation of a sample mixture being separated by a rolled-stationary phase column, resulting separated peaks shown in the chromatogram. PMID:27553948

  2. Surface diffusion in reversed-phase liquid chromatography

    SciTech Connect

    Miyabe, Kanji; Guiochon, Georges A

    2010-01-01

    More than 40 years ago, Giddings pointed out in 'Dynamics of Chromatography' that surface diffusion should become an important research topic in the kinetics of chromatographic phenomena. However, few studies on surface diffusion in adsorbents used in chromatography were published since then. Most scientists use ordinary rate equations to study mass transfer kinetics in chromatography. They take no account of surface diffusion and overlook the significant contributions of this mass transfer process to chromatographic behavior and to column efficiency at high mobile phase flow rate. Only recently did the significance of surface diffusion in separation processes begin to be recognized in connection with the development of new techniques of fast flow, high efficiency chromatography. In this review, we revisit the reports on experimental data on surface diffusion and introduce a surface-restricted molecular diffusion model, derived as a first approximation for the mechanism of surface diffusion, on the basis of the absolute rate theory. We also explain how this model accounts for many intrinsic characteristics of surface diffusion that cannot properly be explained by the conventional models of surface diffusion.

  3. Identification of polychlorinated styrene compounds in heron tissues by gas-liquid chromatography-mass spectrometry

    USGS Publications Warehouse

    Reichel, W.L.; Prouty, R.M.; Gay, M.L.

    1977-01-01

    Unknown compounds detected in Ardea herodias tissues are identified by gas-liquid chromatography-mass spectrometry as residues of octachlorostyrene. Heptachlorostyrene and hexachlorostyrene were tentatively identified.

  4. Applications of liquid chromatography--mass spectrometry in analytical toxicology: a review.

    PubMed

    Hoja, H; Marquet, P; Verneuil, B; Lotfi, H; Pénicaut, B; Lachâtre, G

    1997-01-01

    Liquid chromatography-mass spectrometry (LC-MS), after long-term development that has introduced seven major interfacing techniques, is finally suitable for application in the field of analytical toxicology. Various compound classes can be analyzed, and sensitivities for more or less polar analytes that are as good as or better than those of gas chromatography-mass spectrometry can be obtained with modern interfaces. In addition, because ionization is often softer than classical electron impact, some LC-MS interfaces are able to handle fragile species that are otherwise not amenable to MS. This review is intended to present LC-MS to less familiarized readers and to give an extensive overview of the application of the different coupling techniques to doping agents, drugs of abuse, forensic analysis, toxic compounds of various nature, and several toxicologically relevant therapeutic drugs. Experimental parameters such as the interfaces used, ionization methods, detection limits, and experimental details for exemplary applications are given. PMID:9083829

  5. A new approach for the estimation of expanded uncertainty of results of an analytical method developed for determining antibiotics in seawater using solid-phase extraction disks and liquid chromatography coupled with tandem mass spectrometry technique.

    PubMed

    Borecka, Marta; Białk-Bielińska, Anna; Siedlewicz, Grzegorz; Kornowska, Kinga; Kumirska, Jolanta; Stepnowski, Piotr; Pazdro, Ksenia

    2013-08-23

    Although the uncertainty estimate should be a necessary component of an analytical result, the presentation of measurements together with their uncertainties is still a serious problem, especially in the monitoring of the presence of pharmaceuticals in the environment. Here we discuss the estimation of expanded uncertainty in analytical procedures for determining residues of twelve pharmaceuticals in seawaters using solid-phase extraction (SPE) with H2O-Philic BAKERBOND speed disks and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Matrix effects, extraction efficiency and absolute recovery of the developed analytical method were determined. A validation was performed to obtain the method's linearity, precision, accuracy, limits of detection (LODs) and quantification (LOQs). The expanded uncertainty of the data obtained was estimated according to the Guide to the Expression of Uncertainty in Measurement and ISO 17025:2005 standard. We applied our method to the analysis of drugs in seawaters samples from the coastal area of the southern Baltic Sea. As a result, a new approach (concerning the uncertainty estimation as well as the development of analytical method) to the analysis of pharmaceutical residues in environmental samples is presented. The information given here should facilitate the introduction of uncertainty estimation in chromatographic measurements on a much greater scale than is currently the case.

  6. Supercritical fluid extraction as an on-line clean-up technique for rapid amperometric screening and alternative liquid chromatography for confirmation of paraquat and diquat in olive oil samples.

    PubMed

    Zougagh, M; Bouabdallah, M; Salghi, R; Hormatallah, A; Rios, A

    2008-09-12

    A rapid and simple method for the direct screening of paraquat (PQ) and diquat (DQ) in olive oil samples is proposed. The sample screening method involves supercritical fluid extraction (SFE) (clean-up followed by the extraction of the analytes) followed by continuous flow electrochemical detection. Those samples for which the total concentration is close to or above the threshold limit established by the Columbian Society for Social Protection (0.05 microg g(-1)) are subsequently analyzed by liquid chromatography (LC) with diode array detection (DAD). This confirmation method allows the determination of PQ and DQ in the range between 0.04 and 1.0 microg g(-1), with average relative standard deviations lower than 3.5%, and 0.003 and 0.002 microg g(-1) detection limits for PQ and DQ, respectively. The proposed arrangement opens up interesting prospects for the direct determination of polar pesticides in complex samples with a good throughput and a high level of automation.

  7. Application of ultraperformance liquid chromatography/mass spectrometry-based metabonomic techniques to analyze the joint toxic action of long-term low-level exposure to a mixture of organophosphate pesticides on rat urine profile.

    PubMed

    Du, Longfei; Wang, Hong; Xu, Wei; Zeng, Yan; Hou, Yurong; Zhang, Yuqiu; Zhao, Xiujuan; Sun, Changhao

    2013-07-01

    In previously published articles, we evaluated the toxicity of four organophosphate (OP) pesticides (dichlorvos, dimethoate, acephate, and phorate) to rats using metabonomic technology at their corresponding no observed adverse effect level (NOAEL). Results show that a single pesticide elicits no toxic response. This study aimed to determine whether chronic exposure to a mixture of the above four pesticides (at their corresponding NOAEL) can lead to joint toxic action in rats using the same technology. Pesticides were administered daily to rats through drinking water for 24 weeks. The above mixture of the four pesticides showed joint toxic action at the NOAEL of each pesticide. The metabonomic profiles of rats urine were analyzed by ultraperformance liquid chromatography/mass spectrometry. The 16 metabolites statistically significantly changed in all treated groups compared with the control group. Dimethylphosphate and dimethyldithiophosphate exclusively detected in all treated groups can be used as early, sensitive biomarkers for exposure to a mixture of the OP pesticides. Moreover, exposure to the OP pesticides resulted in increased 7-methylguanine, ribothymidine, cholic acid, 4-pyridoxic acid, kynurenine, and indoxyl sulfate levels, as well as decreased hippuric acid, creatinine, uric acid, gentisic acid, C18-dihydrosphingosine, phytosphingosine, suberic acid, and citric acid. The results indicated that a mixture of OP pesticides induced DNA damage and oxidative stress, disturbed the metabolism of lipids, and interfered with the tricarboxylic acid cycle. Ensuring food safety requires not only the toxicology test data of each pesticide for the calculation of the acceptable daily intake but also the joint toxic action.

  8. A new approach for the estimation of expanded uncertainty of results of an analytical method developed for determining antibiotics in seawater using solid-phase extraction disks and liquid chromatography coupled with tandem mass spectrometry technique.

    PubMed

    Borecka, Marta; Białk-Bielińska, Anna; Siedlewicz, Grzegorz; Kornowska, Kinga; Kumirska, Jolanta; Stepnowski, Piotr; Pazdro, Ksenia

    2013-08-23

    Although the uncertainty estimate should be a necessary component of an analytical result, the presentation of measurements together with their uncertainties is still a serious problem, especially in the monitoring of the presence of pharmaceuticals in the environment. Here we discuss the estimation of expanded uncertainty in analytical procedures for determining residues of twelve pharmaceuticals in seawaters using solid-phase extraction (SPE) with H2O-Philic BAKERBOND speed disks and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Matrix effects, extraction efficiency and absolute recovery of the developed analytical method were determined. A validation was performed to obtain the method's linearity, precision, accuracy, limits of detection (LODs) and quantification (LOQs). The expanded uncertainty of the data obtained was estimated according to the Guide to the Expression of Uncertainty in Measurement and ISO 17025:2005 standard. We applied our method to the analysis of drugs in seawaters samples from the coastal area of the southern Baltic Sea. As a result, a new approach (concerning the uncertainty estimation as well as the development of analytical method) to the analysis of pharmaceutical residues in environmental samples is presented. The information given here should facilitate the introduction of uncertainty estimation in chromatographic measurements on a much greater scale than is currently the case. PMID:23885670

  9. General theory of peak compression in liquid chromatography.

    PubMed

    Gritti, Fabrice

    2016-02-12

    A new and general expression of the peak compression factor in liquid chromatography is derived. It applies to any type of gradients induced by non-uniform columns (stationary) or by temporal variations (dynamic) of the elution strength related to changes in solvent composition, temperature, or in any external field. The new equation is validated in two ideal cases for which the exact solutions are already known. From a practical viewpoint, it is used to predict the achievable degree of peak compression for curved retention models, retained solvent gradients, and for temperature-programmed liquid chromatography. The results reveal that: (1) curved retention models affect little the compression factor with respect to the best linear strength retention models, (2) gradient peaks can be indefinitely compressed with respect to isocratic peaks if the propagation speed of the gradient (solvent or temperature) becomes smaller than the chromatographic velocity, (3) limitations are inherent to the maximum intensity of the experimental intrinsic gradient steepness, and (4) dynamic temperature gradients can be advantageously combined to solvent gradients in order to improve peak capacities of microfluidic separation devices.

  10. An Undergraduate Experiment for the Measurement of Perfluorinated Surfactants in Fish Liver by Liquid Chromatography-Tandem Mass Spectrometry

    ERIC Educational Resources Information Center

    Stock, Naomi L.; Martin, Jonathan W.; Ye, Yun; Mabury, Scott A.

    2007-01-01

    A laboratory experiment that provides students a hands-on introduction to the specific techniques of liquid chromatography-tandem mass spectrometry (LC-MS/MS) and electrospray ionization is presented. The students can thus practice the analytical principles of sample extraction, detection, quantification, and quality control using a fresh fish…

  11. Automated dispersive liquid-liquid microextraction-gas chromatography-mass spectrometry.

    PubMed

    Guo, Liang; Lee, Hian Kee

    2014-04-15

    An innovative automated procedure, low-density solvent based/solvent demulsification dispersive liquid-liquid microextraction (automated DLLME) coupled to gas chromatography-mass spectrometry (GC/MS) analysis, has been developed. The most significant innovation of the method is the automation. The entire procedure, including the extraction of the model analytes (phthalate esters) by DLLME from the aqueous sample solution, breaking up of the emulsion after extraction, collection of the extract, and analysis of the extract by GC/MS, was completely automated. The applications of low-density solvent as extraction solvent and the solvent demulsification technique to break up the emulsion simplified the procedure and facilitated its automation. Orthogonal array design (OAD) as an efficient optimization strategy was employed to optimize the extraction parameters, with all the experiments conducted auotmatically. An OA16 (4(1) × 2(12)) matrix was initially employed for the identification of optimized extraction parameters (type and volume of extraction solvent, type and volume of dispersive solvent and demulsification solvent, demulsification time, and injection speed). Then, on the basis of the results, more levels (values) of five extraction parameters were investigated by an OA16 (4(5)) matrix and quantitatively assessed by the analysis of variance (ANOVA). Enrichment factors of between 178- and 272-fold were obtained for the phthalate esters. The linearities were in the range of 0.1 and 50 μg/L and 0.2 and 50 μg/L, depending on the analytes. Good limits of detection (in the range of 0.01 to 0.02 μg/L) and satisfactory repeatability (relative standard deviations of below 5.9%) were obtained. The proposed method demonstrates for the first time integrated sample preparation by DLLME and analysis by GC/MS that can be operated automatically across multiple experiments.

  12. Determination of organophosphorus pesticides in soil by dispersive liquid-liquid microextraction and gas chromatography.

    PubMed

    Yang, Zhonghua; Liu, Yu; Liu, Donghui; Zhou, Zhiqiang

    2012-01-01

    In this article, a rapid and sensitive sample pretreatment technique for the determination of organophosphorus pesticides (OPPs) in soil samples is developed by using dispersive liquid-liquid microextraction (DLLME) combined with gas chromatography-flame photometric detection. Experimental conditions, including the kind of extraction and disperser solvent and their volumes, the extraction time, and the salt addition, are investigated, and the following experiment factors are used: 20 µL chlorobenzene as the extraction solvent; 1.0 mL acetonitrile as the disperser solvent; no addition of salt; and an extraction time of 1 min. Under the optimum conditions, the linearities for the three target OPPs (ethoprophos, chlorpyriphos, and profenofos) are obtained by five points in the concentration range of 2.5-1500 µg/kg, and three replicates are used for each point. Correlation coefficients vary from 0.9987 to 0.9997. The repeatability is tested by spiking soil samples at a concentration level of 5.0 µg/kg. The relative standard deviation (n = 3) varied between 2.0% and 6.6%. The limits of detection, based on a signal-to-noise ratio (S/N) of 3, range from 200 to 500 pg/g. This method is applied to the analysis of the spiked samples S1, S2, and S3, which are collected from the China Agriculture University's orchard, lawn, and garden, respectively. The recoveries for each target analyte are in the range between 87.9% and 108.0%, 87.4% and 108.0%, and 86.7% and 107.2%, respectively. PMID:22291051

  13. Purification of flavonoids from licorice using an off-line preparative two-dimensional normal-phase liquid chromatography/reversed-phase liquid chromatography method.

    PubMed

    Fan, Yunpeng; Fu, Yanhui; Fu, Qing; Cai, Jianfeng; Xin, Huaxia; Dai, Mei; Jin, Yu

    2016-07-01

    An orthogonal (71.9%) off-line preparative two-dimensional normal-phase liquid chromatography/reversed-phase liquid chromatography method coupled with effective sample pretreatment was developed for separation and purification of flavonoids from licorice. Most of the nonflavonoids were firstly removed using a self-made Click TE-Cys (60 μm) solid-phase extraction. In the first dimension, an industrial grade preparative chromatography was employed to purify the crude flavonoids. Click TE-Cys (10 μm) was selected as the stationary phase that provided an excellent separation with high reproducibility. Ethyl acetate/ethanol was selected as the mobile phase owing to their excellent solubility for flavonoids. Flavonoids co-eluted in the first dimension were selected for further purification using reversed-phase liquid chromatography. Multiple compounds could be isolated from one normal-phase fraction and some compounds with bad resolution in one-dimensional liquid chromatography could be prepared in this two-dimensional system owing to the orthogonal separation. Moreover, this two-dimensional liquid chromatography method was beneficial for the preparation of relatively trace flavonoid compounds, which were enriched in the first dimension and further purified in the second dimension. Totally, 24 flavonoid compounds with high purity were obtained. The results demonstrated that the off-line two-dimensional liquid chromatography method was effective for the preparative separation and purification of flavonoids from licorice.

  14. Enantioselective high performance liquid chromatography and supercritical fluid chromatography separation of spirocyclic terpenoid flavor compounds.

    PubMed

    Schaffrath, Mathias; Weidmann, Verena; Maison, Wolfgang

    2014-10-10

    Chiral spirocyclic terpenoids are abundant natural flavors with significant impact particularly on the food industry. Chromatographic methods for analytical and preparative separation of these compounds are therefore of high interest to natural product chemists in academia and industry. Gas chromatography on chiral stationary phases is currently the standard method for the separation of volatile terpenoids, limiting the scale to analytical quantities. We report herein high performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) protocols for the chiral separation of several racemic spirocyclic terpenoids such as the important flavors theaspirane and vitispirane. A screening of mobile phases and 16 commercially available chiral stationary phases (CSPs) largely based on polysaccharides led to identification of protocols for the separation of all terpenoids tested. SFC methods were found to be particularly useful for the separation of these spirocyclic flavors due to the volatility and low polarity of the compounds. The reported chiral HPLC and SFC protocols are scalable alternatives to gas chromatographic separations of volatile terpenoid flavors.

  15. Enantiomeric separation of organophosphorus pesticides by high-performance liquid chromatography, gas chromatography and capillary electrophoresis and their applications to environmental fate and toxicity assays.

    PubMed

    Li, Ling; Zhou, Shanshan; Jin, Lixia; Zhang, Cheng; Liu, Weiping

    2010-05-15

    In recent years, the continuous evolution of the field of stereochemistry has produced a heightened awareness of the applications of pure enantiomers of agrochemicals. This review describes reports of the enantiomeric separation of commercial organophosphorus pesticides (OPs) and the applications of these methods to research on the enantioselectivity of the toxicity and environmental fate of these compounds. Chiral OPs can be analysed by high-performance liquid chromatography (HPLC), gas chromatography (GC), and capillary electrophoresis (CE). These different separation techniques for OP enantiomers are briefly discussed, and their applications are presented.

  16. Comparison of liquid chromatography-microchip/mass spectrometry to conventional liquid chromatography-mass spectrometry for the analysis of steroids.

    PubMed

    Ahonen, Linda; Keski-Rahkonen, Pekka; Saarelainen, Taija; Paviala, Jenni; Ketola, Raimo A; Auriola, Seppo; Poutanen, Matti; Kostianen, Risto

    2012-04-01

    The feasibility of a microfluidic-based liquid chromatography-electrospray ionization/mass spectrometric system (HPLC-Chip/ESI/MS) was studied and compared to a conventional narrow-bore liquid chromatography-electrospray ionization/mass spectrometric (LC-ESI/MS) system for the analysis of steroids. The limits of detection (LODs) for oxime derivatized steroids, expressed as concentrations, were slightly higher with the HPLC-Chip/MS system (50-300 pM) using an injection volume of 0.5 μL than with the conventional LC-ESI/MS (10-150 pM) using an injection volume of 40 μL. However, when the LODs are expressed as injected amounts, the sensitivity of the HPLC-Chip/MS system was about 50 times higher than with the conventional LC-ESI/MS system. The results indicate that the use of HPLC-Chip/MS system is clearly advantageous only in the analysis of low-volume samples. Both methods showed good linearity and good quantitative and chromatographic repeatability. In addition to the instrument comparisons with oxime derivatized steroids, the feasibility of the HPLC-Chip/MS system in the analysis of non-derivatized and oxime derivatized steroids was compared. The HPLC-Chip/MS method developed for non-derivatized steroids was also applied to the quantitative analysis of 15 mouse plasma samples.

  17. Evaluation between ultrahigh pressure liquid chromatography and high-performance liquid chromatography analytical methods for characterizing natural dyestuffs.

    PubMed

    Serrano, Ana; van Bommel, Maarten; Hallett, Jessica

    2013-11-29

    An evaluation was undertaken of ultrahigh pressure liquid chromatography (UHPLC) in comparison to high-performance liquid chromatography (HPLC) for characterizing natural dyes in cultural heritage objects. A new UHPLC method was optimized by testing several analytical parameters adapted from prior UHPLC studies developed in diverse fields of research. Different gradient elution programs were tested on seven UHPLC columns with different dimensions and stationary phase compositions by applying several mobile phases, flow rates, temperatures, and runtimes. The UHPLC method successfully provided more improved data than that achieved by the HPLC method. Indeed, even though carminic acid has shown circa 146% higher resolution with HPLC, UHPLC resulted in an increase of 41-61% resolution and a decrease of 91-422% limit of detection, depending on the dye compound. The optimized method was subsequently assigned to analyse 59 natural reference materials, in which 85 different components were ascribed with different physicochemical properties, in order to create a spectral database for future characterization of dyes in cultural heritage objects. The majority of these reference samples could be successfully distinguished with one single method through the examination of these compounds' retention times and their spectra acquired with a photodiode array detector. These results demonstrate that UHPLC analyses are extremely valuable for the acquisition of more precise chromatographic information concerning natural dyes with complex mixtures of different and/or closely related physicochemical properties, essential for distinguishing similar species of plants and animals used to colour cultural heritage objects. PMID:24139502

  18. Evaluation between ultrahigh pressure liquid chromatography and high-performance liquid chromatography analytical methods for characterizing natural dyestuffs.

    PubMed

    Serrano, Ana; van Bommel, Maarten; Hallett, Jessica

    2013-11-29

    An evaluation was undertaken of ultrahigh pressure liquid chromatography (UHPLC) in comparison to high-performance liquid chromatography (HPLC) for characterizing natural dyes in cultural heritage objects. A new UHPLC method was optimized by testing several analytical parameters adapted from prior UHPLC studies developed in diverse fields of research. Different gradient elution programs were tested on seven UHPLC columns with different dimensions and stationary phase compositions by applying several mobile phases, flow rates, temperatures, and runtimes. The UHPLC method successfully provided more improved data than that achieved by the HPLC method. Indeed, even though carminic acid has shown circa 146% higher resolution with HPLC, UHPLC resulted in an increase of 41-61% resolution and a decrease of 91-422% limit of detection, depending on the dye compound. The optimized method was subsequently assigned to analyse 59 natural reference materials, in which 85 different components were ascribed with different physicochemical properties, in order to create a spectral database for future characterization of dyes in cultural heritage objects. The majority of these reference samples could be successfully distinguished with one single method through the examination of these compounds' retention times and their spectra acquired with a photodiode array detector. These results demonstrate that UHPLC analyses are extremely valuable for the acquisition of more precise chromatographic information concerning natural dyes with complex mixtures of different and/or closely related physicochemical properties, essential for distinguishing similar species of plants and animals used to colour cultural heritage objects.

  19. Application of liquid-liquid-liquid microextraction and high-performance liquid-chromatography for the determination of sulfonamides in water.

    PubMed

    Lin, Che-Yi; Huang, Shang-Da

    2008-03-31

    This work presents a novel liquid-liquid-liquid microextraction (LLLME) technique for the extraction of sulfonamides from aqueous systems; it combines with high-performance liquid-chromatography-ultraviolet absorbance detection (HPLC/UV). In this experiment the sulfonamides were successively extracted from a donor phase (i.e., a water sample) into several microliters of an organic phase and then from the organic phase into an acceptor phase (i.e., an aqueous extract) by LLLME. The following separation and quantitative analyses were performed using HPLC/UV with 265 nm detection. Extraction condition such as solvent identity, agitation, extraction time, acceptor phase NaOH concentration, donor phase pH, and salt addition were optimized. Relative standard deviation (RSD, 2.6-5.3%), coefficient of estimation (R2, 0.9972-0.9999), and method detection limit (MDL, 0.11-0.77 ng mL(-1)) were achieved under the selected conditions. The proposed method was successfully applied to the analyses of three practical water samples and the relative recoveries of sulfonamides from the spiked water samples were in the range of 86.2-108.7%. The proposed method also confirms microextraction to be robust to monitoring trace levels of sulfacetamide, sulfadiazine, sulfathiazole, sulfamerazine, sulfadimidine, sulfamonomethoxine, sulfamethoxazole, and sulfaquinoxaline in aqueous samples. PMID:18331856

  20. Supercritical Fluid Chromatography, Pressurized Liquid Extraction and Supercritical Fluid Extraction

    SciTech Connect

    Henry, Matthew C.; Yonker, Clement R.

    2006-06-15

    In this review we examine the related fields of supercritical fluid chromatography (SFC) and supercritical fluid extraction (SFE). We reviewed the published literature in the period from November 2003 to November 2005. Well over 300 papers were published in this period. This large body of work indicates continuing active growth of the field, but an exhaustive review is beyond the scope of this work. We have chosen to include a sampling of publications that best represent the continuing trends and new ideas in the field. In keeping with past reviews on this subject1, we have broadened our scope to include fluid systems operating at high temperature and pressure, but below the critical point. Various terms have been applied to this state: sub-critical fluid extraction, pressurized liquid extraction, and accelerated solvent extraction. The term accelerated solvent extraction has been used by instrument manufacturers to refer to this process, but we will use the more descriptive term pressurized liquid extraction (PLE) to refer to these systems. Most of the research in the field is of an “evolutionary” rather than “revolutionary” nature. As in the previous review period, applications papers make up a majority of the published work. Pharmaceutical applications continue to be a strong theme. Most of the pharmaceutical work has centered on preparative, rather than analytical, separations. Chiral separations are an exception, as analytical scale separations of chiral compounds are an area of intense interest. Food and natural products represent the next largest body of work. Major themes are the isolation and characterization of high-value added foodstuffs, fragrances, and flavor compounds from novel natural materials or agricultural by-products. The areas of food, natural products, and pharmaceutical separation science converge in the area of so-called nutraceuticals. These are typically high-value products, either sold alone or as part of a fortified food, that

  1. Method transfer from high-pressure liquid chromatography to ultra-high-pressure liquid chromatography. II. Temperature and pressure effects.

    PubMed

    Åsberg, Dennis; Samuelsson, Jörgen; Leśko, Marek; Cavazzini, Alberto; Kaczmarski, Krzysztof; Fornstedt, Torgny

    2015-07-01

    The importance of the generated temperature and pressure gradients in ultra-high-pressure liquid chromatography (UHPLC) are investigated and compared to high-pressure liquid chromatography (HPLC). The drug Omeprazole, together with three other model compounds (with different chemical characteristics, namely uncharged, positively and negatively charged) were used. Calculations of the complete temperature profile in the column at UHPLC conditions showed, in our experiments, a temperature difference between the inlet and outlet of 16 °C and a difference of 2 °C between the column center and the wall. Through van't Hoff plots, this information was used to single out the decrease in retention factor (k) solely due to the temperature gradient. The uncharged solute was least affected by temperature with a decrease in k of about 5% while for charged solutes the effect was more pronounced, with k decreases up to 14%. A pressure increase of 500 bar gave roughly 5% increase in k for the uncharged solute, while omeprazole and the other two charged solutes gave about 25, 20 and 15% increases in k, respectively. The stochastic model of chromatography was applied to estimate the dependence of the average number of adsorption/desorption events (n) and the average time spent by a molecule in the stationary phase (τs) on temperature and pressure on peak shape for the tailing, basic solute. Increasing the temperature yielded an increase in n and decrease in τs which resulted in less skew at high temperatures. With increasing pressure, the stochastic modeling gave interesting results for the basic solute showing that the skew of the peak increased with pressure. The conclusion is that pressure effects are more pronounced for both retention and peak shape than the temperature effects for the polar or charged compounds in our study.

  2. Improved characterization of tomato polyphenols using liquid chromatography/electrospray ionization linear ion trap quadrupole Orbitrap mass spectrometry and liquid chromatography/electrospray ionization tandem mass spectrometry.

    PubMed

    Vallverdú-Queralt, Anna; Jáuregui, Olga; Medina-Remón, Alexander; Andrés-Lacueva, Cristina; Lamuela-Raventós, Rosa M

    2010-10-30

    Tomato (Lycopersicon esculentum Mill.) is the second most important fruit crop worldwide. Tomatoes are a key component in the Mediterranean diet, which is strongly associated with a reduced risk of chronic degenerative diseases. In this work, we use a combination of mass spectrometry (MS) techniques with negative ion detection, liquid chromatography/electrospray ionization linear ion trap quadrupole-Orbitrap-mass spectrometry (LC/ESI-LTQ-Orbitrap-MS) and liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) on a triple quadrupole, for the identification of the constituents of tomato samples. First, we tested for the presence of polyphenolic compounds through generic MS/MS experiments such as neutral loss and precursor ion scans on the triple quadrupole system. Confirmation of the compounds previously identified was accomplished by injection into the high-resolution system (LTQ-Orbitrap) using accurate mass measurements in MS, MS(2) and MS(3) modes. In this way, 38 compounds were identified in tomato samples with very good mass accuracy (<2 mDa), three of them, as far as we know, not previously reported in tomato samples.

  3. Liquid chromatography-mass spectrometric and liquid chromatography-tandem mass spectrometric determination of hallucinogenic indoles psilocin and psilocybin in "magic mushroom" samples.

    PubMed

    Kamata, Tooru; Nishikawa, Mayumi; Katagi, Munehiro; Tsuchihashi, Hitoshi

    2005-03-01

    Accurate and sensitive analytical methods for psilocin (PC) and psilocybin (PB), tryptamine-type hallucinogens contained in "magic mushrooms," were investigated using liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS-MS). The chromatographic separation on an ODS column and mass spectral information gave complete discrimination between PC and PB without derivatization. The mass spectrometric detection had a high sensitivity, and the tandem mass spectrometric detection provided more specificity and accuracy, as well as high sensitivity. The detection limits ranged from 1 to 25 pg by LC-MS in the selected ion monitoring mode, and the intra- and inter-day coefficients of variation were estimated to be 4.21-5.93% by LC-MS-MS in the selected reaction monitoring mode. By applying the present LC-MS-MS technique to four real samples, the contents of PC and PB were found to vary over a wide range (0.60-1.4 and 0.18-3.8 mg/g dry wt. for PC and PB, respectively) between samples.

  4. On-line comprehensive two-dimensional normal-phase liquid chromatography × reversed-phase liquid chromatography for preparative isolation of Peucedanum praeruptorum.

    PubMed

    Wang, Xin-Yuan; Li, Jia-Fu; Jian, Ya-Mei; Wu, Zhen; Fang, Mei-Juan; Qiu, Ying-Kun

    2015-03-27

    A new on-line comprehensive preparative two-dimensional normal-phase liquid chromatography × reversed-phase liquid chromatography (2D NPLC × RPLC) system was developed for the separation of complicated natural products. It was based on the use of a silica gel packed medium-pressure column as the first dimension and an ODS preparative HPLC column as the second dimension. The two dimensions were connected with normal-phase (NP) and reversed-phase (RP) enrichment units, involving a newly developed airflow assisted adsorption (AAA) technique. The instrument operation and the performance of this NPLC × RPLC separation method were illustrated by gram-scale isolation of ethanol extract from the roots of Peucedanum praeruptorum. In total, 19 compounds with high purity were obtained via automated multi-step preparative separation in a short period of time using this system, and their structures were comprehensively characterized by ESI-MS, (1)H NMR, and (13)C NMR. Including two new compounds, five isomers in two groups with identical HPLC and TLC retention values were also obtained and identified by 1D NMR and 2D NMR. This is the first report of an NPLC × RPLC system successfully applied in an on-line preparative process. This system not only solved the interfacing problem of mobile-phase immiscibility caused by NP and RP separation, it also exhibited apparent advantages in separation efficiency and sample treatment capacity compared with conventional methods.

  5. Separation of organophosphorus pesticides by using nano-liquid chromatography.

    PubMed

    Buonasera, Katia; D'Orazio, Giovanni; Fanali, Salvatore; Dugo, Paola; Mondello, Luigi

    2009-05-01

    In the present research, the separation of a series of organophosphorus pesticides (fensulfothion, fenamiphos, profenofos, fonofos, isofenphos, dialifos, sulprofos and prothiofos), by using nano-liquid chromatography (nano-LC) with UV detection is described. Three 100 microm ID capillary columns, packed with different silica-based stationary phases (CN, C(18), and phenyl), were investigated. Among these, the phenyl column offered the best results in terms of chromatographic performance, and was selected for pesticide analyses. Parameters, such as sample dilution solvent, injection volume, mobile phase composition and flow rate, were optimized in order to define the ideal experimental conditions. With the aim of improving sensitivity, on-column focusing of large injection volumes was applied: a sensitivity increase of circa 100-fold was attained, with limits of detection (LODs) and quantification (LOQs) within the 4.4-37.5 and 14.5-125.0 ng/mL ranges, respectively. The method was validated, with satisfactory results, through the measurement of the following parameters: limits of detection and quantification, precision, linearity and recovery. Finally, five different baby foods, previously fortified with a solution of the eight aforementioned pesticides, and then subjected to liquid-liquid extraction and solid-phase extraction clean-up, were analyzed. PMID:19321170

  6. Analysis of quality of aviation lubricating oils by means of liquid and gas-liquid chromatography

    SciTech Connect

    Kholostova, G.G.; Bakunin, V.N.; Shimonaev, G.S.

    1987-01-01

    The authors examine the basic methodological aspects of chromatographic analysis of the quality of oils for aircraft gas turbine engines, and certain relationships in oil aging that have been established on this basis. A commercial ester (designated PEE) was selected for investigation of pentaerythritol and C/sub 5/-C/sub 9/ synthetic fatty acids (SFA) which serves as the synthetic base stock for a number of aviation oils. The changes in PEE composition upon oxidation, with or without additives, were evaluated by means of gas-liquid chromatography in a Tsvet-100 chromatograph with a flame ionization detector. The results from examination of the original and oxidized PEE samples by means of gas and liquid chromatography are presented.

  7. Liquid chromatography-mass spectrometry in metabolomics research: mass analyzers in ultra high pressure liquid chromatography coupling.

    PubMed

    Forcisi, Sara; Moritz, Franco; Kanawati, Basem; Tziotis, Dimitrios; Lehmann, Rainer; Schmitt-Kopplin, Philippe

    2013-05-31

    The present review gives an introduction into the concept of metabolomics and provides an overview of the analytical tools applied in non-targeted metabolomics with a focus on liquid chromatography (LC). LC is a powerful analytical tool in the study of complex sample matrices. A further development and configuration employing Ultra-High Pressure Liquid Chromatography (UHPLC) is optimized to provide the largest known liquid chromatographic resolution and peak capacity. Reasonably UHPLC plays an important role in separation and consequent metabolite identification of complex molecular mixtures such as bio-fluids. The most sensitive detectors for these purposes are mass spectrometers. Almost any mass analyzer can be optimized to identify and quantify small pre-defined sets of targets; however, the number of analytes in metabolomics is far greater. Optimized protocols for quantification of large sets of targets may be rendered inapplicable. Results on small target set analyses on different sample matrices are easily comparable with each other. In non-targeted metabolomics there is almost no analytical method which is applicable to all different matrices due to limitations pertaining to mass analyzers and chromatographic tools. The specifications of the most important interfaces and mass analyzers are discussed. We additionally provide an exemplary application in order to demonstrate the level of complexity which remains intractable up to date. The potential of coupling a high field Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (ICR-FT/MS), the mass analyzer with the largest known mass resolving power, to UHPLC is given with an example of one human pre-treated plasma sample. This experimental example illustrates one way of overcoming the necessity of faster scanning rates in the coupling with UHPLC. The experiment enabled the extraction of thousands of features (analytical signals). A small subset of this compositional space could be mapped into a mass

  8. Sheath liquid effects in capillary high-performance liquid chromatography-electrospray mass spectrometry of oligonucleotides.

    PubMed

    Huber, C G; Krajete, A

    2000-02-18

    Fused-silica capillary columns of 200 microm inner diameter were packed with micropellicular, octadecylated, 2.3 microm poly(styrene-divinylbenzene) particles and applied to the separation of oligonucleotides by ion-pair reversed-phase high-performance liquid chromatography. Oligonucleotides were eluted at 50 degrees C with gradients of 3-13% acetonitrile in 50 mM triethylammonium bicarbonate. Addition of sheath liquid to the column effluent allowed the detection of oligonucleotides by electrospray ionization mass spectrometry using full-scan data acquisition with a detectability comparable to that obtained with UV detection. The signal-to-noise ratios with different sheath liquids increased in the order isopropanolliquid was found to influence the charge state distribution of oligonucleotides longer than 20 nucleotide units whereas no significant effect was observed with shorter oligonucleotides. Organic acids and bases in the sheath liquid generally deteriorated the signal-to-noise ratios in the chromatograms and mass spectra mainly because of increased background noise. Only a few charge states were observed in the mass spectra of oligonucleotides because of charge state reduction due to the presence of carbonic acid in the eluent. With triethylammonium hydrogencarbonate as chromatographic eluent and acetonitrile as sheath liquid, very few cation adducts of oligonucleotides were observed in the mass spectra. However, the presence of small amounts of monopotassium adducts enabled the calculation of the charge state of multiply charged ions. With acetonitrile as sheath liquid, 710 amol of a 16-mer oligonucleotide were detected using selected ion monitoring data acquisition with a signal-to-noise ratio of 3:1. Finally, capillary ion-pair reversed-phase high-performance liquid chromatography-electrospray ionization mass spectrometry was

  9. Investigating the Retention Mechanisms of Liquid Chromatography Using Solid-Phase Extraction Cartridges

    ERIC Educational Resources Information Center

    O'Donnell, Mary E.; Musial, Beata A.; Bretz, Stacey Lowery; Danielson, Neil D.; Ca, Diep

    2009-01-01

    Liquid chromatography (LC) experiments for the undergraduate analytical laboratory course often illustrate the application of reversed-phase LC to solve a separation problem, but rarely compare LC retention mechanisms. In addition, a high-performance liquid chromatography instrument may be beyond what some small colleges can purchase. Solid-phase…

  10. Ultra high pressure liquid chromatography for crude plant extract profiling.

    PubMed

    Eugster, Philippe J; Guillarme, Davy; Rudaz, Serge; Veuthey, Jean-Luc; Carrupt, Pierre-Alain; Wolfender, Jean-Luc

    2011-01-01

    Ultra high pressure liquid chromatography (UHPLC) systems operating at very high pressures and using sub-2 microm packing columns have allowed a remarkable decrease in analysis time and increase in peak capacity, sensitivity, and reproducibility compared to conventional HPLC. This technology has rapidly been widely accepted by the analytical community and is being gradually applied to various fields of plant analysis such as QC, profiling and fingerprinting, dereplication, and metabolomics. For many applications, an important improvement of the overall performances has been reported. In this review, the basic principles of UHPLC are summarized, and practical information on the type of columns used and phase chemistry available is provided. An overview of the latest applications to natural product analysis in complex mixtures is given, and the potential and limitations as well as some new trends in the development of UHPLC are discussed.

  11. A rapid liquid chromatography determination of free formaldehyde in cod.

    PubMed

    Storey, Joseph M; Andersen, Wendy C; Heise, Andrea; Turnipseed, Sherri B; Lohne, Jack; Thomas, Terri; Madson, Mark

    2015-01-01

    A rapid method for the determination of free formaldehyde in cod is described. It uses a simple water extraction of formaldehyde which is then derivatised with 2,4-dinitrophenylhydrazine (DNPH) to form a sensitive and specific chromophore for high-performance liquid chromatography (HPLC) detection. Although this formaldehyde derivative has been widely used in past tissue analysis, this paper describes an improved derivatisation procedure. The formation of the DNPH formaldehyde derivative has been shortened to 2 min and a stabilising buffer has been added to the derivative to increase its stability. The average recovery of free formaldehyde in spiked cod was 63% with an RSD of 15% over the range of 25-200 mg kg(-1) (n = 48). The HPLC procedure described here was also compared to a commercial qualitative procedure - a swab test for the determination of free formaldehyde in fish. Several positive samples were compared by both methods.

  12. Determination of sulfonamide residues in eggs by liquid chromatography.

    PubMed

    Furusawa, Naoto

    2002-01-01

    A method was developed for determining residual sulfonamide antibacterials such as sulfamethazine (SMZ), sulfamonomethoxine (SMM), sulfadimethoxine (SDM), and sulfaquinoxaline (SQ) in eggs using liquid chromatography with a photodiode array detector. The spiked and blank samples were cleaned up by using an Ultrafree-MC/PL centrifugal ultrafiltration unit. A Mightysil RP-4 GP column and a mobile phase of 28% (v/v) ethanol-H2O with a photodiode array detector were used for the determination. Average recoveries from eggs spiked with each drug at 0.1, 0.2, 0.4, and 1.0 ppm were > or = 80.9%, with relative standard deviations between 1.3 and 4.7%. The limits of quantitation were 0.060 ppm for SMZ, 0.045 for SMM, 0.044 for SDM, and 0.093 for SQ. The analysis of one sample required < 30 min and < 5 mL ethanol as solvent. PMID:12180677

  13. High-pressure liquid chromatography of caffeine in coffee.

    PubMed

    Madison, B L; Kozarek, W J; Damo, C P

    1976-11-01

    A new method is described for the determination of caffeine in coffee, based on high-pressure liquid chromatography. The caffeine is extracted from the sample with water and/or methylene chloride, and then separated from interfering materials by passing an aliquot of the extract through a high-pressure column containing sulfonated cation exchange resin, using 0.01M nitric acid as the mobile phase. An ultraviolet detector measures the absorption of the solution directly. The method is rapid and eliminates the lengthy separations common to other methods. The procedure was applied successfully to decaffeinated and non-decaffeinated green, roasted, and instant coffees. This method gives a more accurate measure of the caffeine content in decaffeinated coffee samples than the micro Bailey-Andrew and modified Levine methods, with equal or better precision. This method gives results equal to those obtained by the official methods for non-decaffeinated samples. PMID:993180

  14. Normal-phase high-performance liquid chromatography of triacylglycerols.

    PubMed

    Rhodes, S H; Netting, A G

    1988-08-31

    Triacylglycerols have been separated by normal-phase high-performance liquid chromatography (HPLC) on silica utilising a solvent system consisting of dry acetonitrile-half water saturated hexane (0.7:99.3). This solvent system is UV transparent allowing detection at 200 nm and affords a separation in which retention is primarily dependent on the number of constituent double bonds. There is also a slight separation on chainlength, the longer chainlengths being eluted first. The system is therefore complementary to currently used reversed-phase HPLC systems. Chromatograms for some polyunsaturated fats and oils are given, and the most polyunsaturated triacylglycerols from linseed oil are analysed in more detail. Data are given for the separation and quantitation of the pentafluorobenzyl esters of constituent fatty acids from these triacylglycerols by a similar normal-phase HPLC system.

  15. Effect of temperature in reversed phase liquid chromatography.

    PubMed

    Guillarme, D; Heinisch, S; Rocca, J L

    2004-10-15

    The high temperature liquid chromatography (HTLC) reveals interesting chromatographic properties but even now, it misses some theoretical aspects concerning the influence of high temperature on thermodynamic and kinetic aspects of chromatography: such a knowledge is very essential for method development. In this work, the effect of temperature on solute behavior has been studied using various stationary phases which are representative of the available thermally stable materials present on the market. The thermodynamic properties were evaluated by using different mobile phases: acetonitrile-water, methanol-water and pure water. The obtained results were discussed on the basis of both type of mobile phases and type of stationary phases. Type of mobile phase was found to play an important role on the retention of solutes. The kinetic aspect was studied at various temperatures ranging from ambient temperature to high temperature (typically from about 30 to 200 degrees C) by fitting the experimental data with the Knox equation and it was shown that the efficiency is improved significantly when the temperature is increased. In this paper, we also discussed the problem of temperature control for thermostating columns which may represent a significant source of peak broadening: by taking into account the three main parameters such as heat transfer, pressure drop and band broadening resulting from the preheating tube, suitable rules are set up for a judicious choice of the column internal diameter. PMID:15527119

  16. High-throughput multiclass method for antibiotic residue analysis by liquid chromatography-tandem mass spectrometry.

    PubMed

    Chico, J; Rúbies, A; Centrich, F; Companyó, R; Prat, M D; Granados, M

    2008-12-12

    A simple and rapid method has been developed for the residue analysis of 39 antibiotics (tetracyclines, quinolones, penicillins, sulfonamides and macrolides) in foodstuffs of animal origin. The method combines an effective extraction technique, which uses water-methanol as extracting solvent, with ultra-high-pressure liquid chromatography-tandem mass spectrometry, allowing both confirmation and quantification in a single chromatographic run. The multiresidue method has been validated in chicken muscle matrix according to European Union Decision 2002/657/EC. It has been implemented as a routine method in a Public Health Laboratory, instead of the five plates test and LC methods previously used.

  17. High-throughput multiclass method for antibiotic residue analysis by liquid chromatography-tandem mass spectrometry.

    PubMed

    Chico, J; Rúbies, A; Centrich, F; Companyó, R; Prat, M D; Granados, M

    2008-12-12

    A simple and rapid method has been developed for the residue analysis of 39 antibiotics (tetracyclines, quinolones, penicillins, sulfonamides and macrolides) in foodstuffs of animal origin. The method combines an effective extraction technique, which uses water-methanol as extracting solvent, with ultra-high-pressure liquid chromatography-tandem mass spectrometry, allowing both confirmation and quantification in a single chromatographic run. The multiresidue method has been validated in chicken muscle matrix according to European Union Decision 2002/657/EC. It has been implemented as a routine method in a Public Health Laboratory, instead of the five plates test and LC methods previously used. PMID:18992888

  18. Mapping protein abundance patterns in the brain using voxelation combined with liquid chromatography and mass spectrometry

    SciTech Connect

    Petyuk, Vladislav A.; Qian, Weijun; Smith, Richard D.; Smith, Desmond J.

    2010-02-01

    Voxelation creates expression atlases by high-throughput analysis of spatially registered cubes or voxels harvested from the brain. The modality independence of voxelation allows a variety of bioanalytical techniques to be used to map abundance. Protein expression patterns in the brain can be obtained using liquid chromatography (LC) combined with mass spectrometry (MS). Here we describe the methodology of voxelation as it pertains particularly to LC-MS proteomic analysis: sample preparation, instrumental set up and analysis, peptide identification and protein relative abundance quantitation. We also briefly describe some of the advantages, limitations and insights into the brain that can be obtained using combined proteomic and transcriptomic maps

  19. Determination of Atmospheric Hydroxyl Radical by Liquid Phase Scrubbing and High Performance Liquid Chromatography.

    NASA Astrophysics Data System (ADS)

    Chen, Xiaohui

    A new in situ method for determining atmospheric hydroxyl radical (OH) was developed. This method is based on liquid phase scrubbing technique and high performance liquid chromatography (LPS-HPLC). The sampling system employs glass bubblers to trap atmospheric OH into a buffered solution containing the chemical probe, salicylic acid (o-hydroxybenzoic acid, OHBA). The reaction of OHBA with OH produces a stable fluorescent product, 2,5-dihydroxybenzoic acid (2,5-DHBA), which is determined by reverse phase HPLC and fluorescence detection. The atmospheric OH concentration ( (OH)) is inferred from the resulting 2,5-DHBA amount in the aqueous scrubbing solution, fraction of 2,5-DHBA in the products, air sampling flow rate, sampling time, local pressure and temperature, etc. HPLC separation efficiency and fluorescence detection sensitivity for 2,5-DHBA have been studied. The results indicate that: the reagent blank can be controlled by suitable recrystallization; pH affects both separation and detection processes; the fluorometer should be adjusted to reach its highest signal-to-noise ratio by light source selection, flow cell size selection, wavelength selection, etc. Preliminary column switch experiments reveal the possibility to automate the whole sampling and detection system to enhance the temporal resolution. During an intercomparison of tropospheric OH measurement techniques at the Caribou site, CO (relatively unpolluted air) in Fall 1993, overlapping data were obtained with long path absorption and ion-assisted coupled with MS methods. LPS -HPLC day-time (OH) s, which range from {< }10^6 to 6times10 ^6 radicals/cm^3, agree well with those derived from the other two methods, especially the latter. LPS-HPLC (OH) depends linearly on the combined effects of solar flux, ozone and water vapor, however, it has a nonlinear dependence on NO _{x} and hydrocarbons. These results are consistent with that predicted from photochemical models. Experimental results and model

  20. High-performance liquid chromatography separation of unsaturated organic compounds by a monolithic silica column embedded with silver nanoparticles.

    PubMed

    Zhu, Yang; Morisato, Kei; Hasegawa, George; Moitra, Nirmalya; Kiyomura, Tsutomu; Kurata, Hiroki; Kanamori, Kazuyoshi; Nakanishi, Kazuki

    2015-08-01

    The optimization of a porous structure to ensure good separation performances is always a significant issue in high-performance liquid chromatography column design. Recently we reported the homogeneous embedment of Ag nanoparticles in periodic mesoporous silica monolith and the application of such Ag nanoparticles embedded silica monolith for the high-performance liquid chromatography separation of polyaromatic hydrocarbons. However, the separation performance remains to be improved and the retention mechanism as compared with the Ag ion high-performance liquid chromatography technique still needs to be clarified. In this research, Ag nanoparticles were introduced into a macro/mesoporous silica monolith with optimized pore parameters for high-performance liquid chromatography separations. Baseline separation of benzene, naphthalene, anthracene, and pyrene was achieved with the theoretical plate number for analyte naphthalene as 36,000 m(-1). Its separation function was further extended to cis/trans isomers of aromatic compounds where cis/trans stilbenes were chosen as a benchmark. Good separation of cis/trans-stilbene with separation factor as 7 and theoretical plate number as 76,000 m(-1) for cis-stilbene was obtained. The trans isomer, however, is retained more strongly, which contradicts the long- established retention rule of Ag ion chromatography. Such behavior of Ag nanoparticles embedded in a silica column can be attributed to the differences in the molecular geometric configuration of cis/trans stilbenes.

  1. Determination of sulfonamides in butter samples by ionic liquid magnetic bar liquid-phase microextraction high-performance liquid chromatography.

    PubMed

    Wu, Lijie; Song, Ying; Hu, Mingzhu; Xu, Xu; Zhang, Hanqi; Yu, Aimin; Ma, Qiang; Wang, Ziming

    2015-01-01

    A novel, simple, and environmentally friendly pretreatment method, ionic liquid magnetic bar liquid-phase microextraction, was developed for the determination of sulfonamides in butter samples by high-performance liquid chromatography. The ionic liquid magnetic bar was prepared by inserting a stainless steel wire into the hollow of a hollow fiber and immobilizing ionic liquid in the micropores of the hollow fiber. In the extraction process, the ionic liquid magnetic bars were used to stir the mixture of sample and extraction solvent and enrich the sulfonamides in the mixture. After extraction, the analyte-adsorbed ionic liquid magnetic bars were readily isolated with a magnet from the extraction system. It is notable that the present method was environmentally friendly since water and only several microliters of ionic liquid were used in the whole extraction process. Several parameters affecting the extraction efficiency were investigated and optimized, including the type of ionic liquid, sample-to-extraction solvent ratio, the number of ionic liquid magnetic bars, extraction temperature, extraction time, salt concentration, stirring speed, pH of the extraction solvent, and desorption conditions. The recoveries were in the range of 73.25-103.85 % and the relative standard deviations were lower than 6.84 %. The experiment results indicated that the present method was effective for the extraction of sulfonamides in high-fat content samples.

  2. Practice on high performance liquid chromatography. Applications, equipment, and quantitative analysis

    SciTech Connect

    Engelhardt, H.

    1986-01-01

    The title of this book suggests yet another general text on the principles and practice of HPLC-of which there are at least a dozen currently available. This is not the case, however. Instead, the editor has assembled a series of more specialized chapters addressed to the experienced chromatographer. That is, it is assumed that the reader has already been exposed to a more general and basic book on HPLC. Thus, there is no general discussion of the principles of separation, extracolumn effects, how an HPLC procedure is developed, column packings and techniques for reversed-phase HPLC, etc. The first five chapters of the book deal with equipment, quantitative analysis, preparative HPLC, column switching, and sample pretreatment. This paper of the book contains useful material not often seen in other books or review articles. The next two chapters deal with liquid-liquid and ion pair chromatography but ignore reversed-phase, normal-phase, and ion exchange chromatography. The final eight chapters deal with applications in different areas: inorganic samples, forensic chemistry, lipids, nucleic acid metabolites, drugs of pharmaceutical interest, amino acids, proteins, and coal and oil products. To summarize, this book is something between a basic text on HPLC and a review series such as Giddings's Advances in Chromatography. Whereas every practicing chromatographer should have a book of the first kind, libraries are the usual customers for the second kind. The author found this book useful in a variety of ways and so should many other reader.

  3. Determination of household chemicals using gas chromatography and liquid chromatography with tandem mass spectrometry.

    PubMed

    Trenholm, Rebecca A; Vanderford, Brett J; Drewes, Jörg E; Snyder, Shane A

    2008-05-01

    A method has been developed for the determination of 24 household high production volume (HPV) chemicals in municipal wastewater systems using solid-phase extraction (SPE) and analyses using both gas chromatography and liquid chromatography, each with tandem mass spectrometry (GC-MS/MS and LC-MS/MS). Target compounds include pesticides, antioxidants, fragrances, plasticizers, preservatives and personal care products. Method reporting limits ranged from 0.1 to 100 ng/L in water and recoveries for most compounds were between 54 and 112%. Household HPVs were consistently detected in raw sewage entering three full-scale wastewater treatment plants. Compounds such as vanillin, DEET, benzophenone, 3-indolebutyric acid, bisphenol A, triclosan and triclocarban were detected in all wastewater influent and effluent samples, but were significantly lower in the effluent. Many of the remaining compounds were detected in the influent, but below detection in effluent samples. Menthol and phenoxyethanol had the highest observed concentrations in influent samples ranging from 1.5 to 13 microg/L for menthol, and 8.8 to 22 microg/L for phenoxyethanol. MGK-11, methylresorcinol, trifluralin, hexabromododecane, acriflavin and atrazine were not detected in any samples. The method described here detects a broad range of HPV chemicals with great sensitivity and selectivity.

  4. A sensitive microextraction by packed sorbent-based methodology combined with ultra-high pressure liquid chromatography as a powerful technique for analysis of biologically active flavonols in wines.

    PubMed

    Silva, Catarina L; Gonçalves, João L; Câmara, José S

    2012-08-20

    A new approach based on microextraction by packed sorbent (MEPS) and reversed-phase high-throughput ultra high pressure liquid chromatography (UHPLC) method that uses a gradient elution and diode array detection to quantitate three biologically active flavonols in wines, myricetin, quercetin, and kaempferol, is described. In addition to performing routine experiments to establish the validity of the assay to internationally accepted criteria (selectivity, linearity, sensitivity, precision, accuracy), experiments are included to assess the effect of the important experimental parameters such as the type of sorbent material (C2, C8, C18, SIL, and C8/SCX), number of extraction cycles (extract-discard), elution volume, sample volume, and ethanol content, on the MEPS performance. The optimal conditions of MEPS extraction were obtained using C8 sorbent and small sample volumes (250μL) in five extraction cycle and in a short time period (about 5min for the entire sample preparation step). Under optimized conditions, excellent linearity (R(values)(2)>0.9963), limits of detection of 0.006μgmL(-1) (quercetin) to 0.013μgmL(-1) (myricetin) and precision within 0.5-3.1% were observed for the target flavonols. The average recoveries of myricetin, quercetin and kaempferol for real samples were 83.0-97.7% with relative standard deviation (RSD, %) lower than 1.6%. The results obtained showed that the most abundant flavonol in the analyzed samples was myricetin (5.8±3.7μgmL(-1)). Quercetin (0.97±0.41μgmL(-1)) and kaempferol (0.66±0.24μgmL(-1)) were found in a lower concentration. The optimized MEPS(C8) method was compared with a reverse-phase solid-phase extraction (SPE) procedure using as sorbent a macroporous copolymer made from a balanced ratio of two monomers, the lipophilic divinylbenzene and the hydrophilic N-vinylpyrrolidone (Oasis HLB) were used as reference. MEPS(C8) approach offers an attractive alternative for analysis of flavonols in wines, providing a number of

  5. Hyphenated and comprehensive liquid chromatography × gas chromatography-mass spectrometry for the identification of Mycobacterium tuberculosis.

    PubMed

    Mourão, Marta P B; Denekamp, Ilse; Kuijper, Sjoukje; Kolk, Arend H J; Janssen, Hans-Gerd

    2016-03-25

    Tuberculosis is one of the world's most emerging public health problems, particularly in developing countries. Chromatography based methods have been used to tackle this epidemic by focusing on biomarker detection. Unfortunately, interferences from lipids in the sputum matrix, particularly cholesterol, adversely affect the identification and detection of the marker compounds. The present contribution describes the serial combination of normal phase liquid chromatography (NPLC) with thermally assisted hydrolysis and methylation followed by gas chromatography-mass spectrometry (THM-GC-MS) to overcome the difficulties of biomarker evaluation. The in-series combination consists of an LC analysis where fractions are collected and then transferred to the THM-GC-MS system. This was either done with comprehensive coupling, transferring all the fractions, or with hyphenated interfacing, i.e. off-line multi heart-cutting, transferring only selected fractions. Owing to the high sensitivity and selectivity of LC as a sample pre-treatment method, and to the high specificity of the MS as a detector, this analytical approach, NPLC × THM-GC-MS, is extremely sensitive. The results obtained indicate that this analytical set-up is able to detect down to 1 × 10(3) mycobacteria/mL of Mycobacterium tuberculosis strain 124, spiked in blank sputum samples. It is a powerful analytical tool and also has great potential for full automation. If further studies demonstrate its usefulness when applied blind in real sputum specimens, this technique could compete with the current smear microscopy in the early diagnosis of tuberculosis. PMID:26585206

  6. Liquid chromatography-fluorescence and liquid chromatography-mass spectrometry detection of tryptophan degradation products of a recombinant monoclonal antibody.

    PubMed

    Nowak, Christine; Ponniah, Gomathinayagam; Cheng, Guilong; Kita, Adriana; Neill, Alyssa; Kori, Yekaterina; Liu, Hongcheng

    2016-03-01

    Light exposure is one of several conditions used to study the degradation pathways of recombinant monoclonal antibodies. Tryptophan is of particular interest among the 20 amino acids because it is the most photosensitive. Tryptophan degradation forms several products, including an even stronger photosensitizer and several reactive oxygen species. The current study reports a specific peptide mapping procedure to monitor tryptophan degradation. Instead of monitoring peptides using UV 214 nm, fluorescence detection with an excitation wavelength of 295 nm and an emission wavelength of 350 nm was used to enable specific detection of tryptophan-containing peptides. Peaks that decreased in area over time are likely to contain susceptible tryptophan residues. This observation can allow further liquid chromatography-mass spectrometry (LC-MS) analysis to focus only on those peaks to confirm tryptophan degradation products. After confirmation of tryptophan degradation, susceptibility of tryptophan residues can be compared based on the peak area decrease. PMID:26717898

  7. Limonene in Arizona liquid systems used in countercurrent chromatography. I Physicochemical properties.

    PubMed

    Faure, Karine; Bouju, Elodie; Suchet, Pauline; Berthod, Alain

    2014-09-01

    Limonene is a biorenewable cycloterpene solvent derived from orange peel waste. Its potential as a "green" solvent to replace heptane was recently evaluated. Countercurrent chromatography (CCC) is a preparative separation technique using biphasic liquid systems. One liquid phase is the mobile phase; the other liquid phase is the stationary phase held in place by centrifugal fields. A particular range of special proportions of the heptane/ethyl acetate/methanol/water system is called the Arizona (AZ) liquid system when the heptane/ethyl acetate ratio is exactly the same as the methanol/water ratio. A continuous polarity decrease is obtained between the most polar A composition (ethyl acetate/water or 0/1/0/1 v/v) and the least polar Z composition (heptane/methanol or 1/0/1/0 v/v), replacing heptane by limonene and methanol by ethanol produce biphasic liquid systems much more environmentallyfriendly than the original AZ compositions. The chemical compositions of the two liquid phases of 12 AZ limonene/ethyl acetate/ethanol/water proportions were fully determined by Karl-Fisher titration of water and by gas chromatography for the organic solvents. The results were compared with the compositions of the corresponding AZ mixtures containing heptane and methanol. Significant differences in ethyl acetate and ethanol distribution between phases of the two systems with identical volume proportions were established. The ratio of the upper phase over the lower phase volumes and the phase density difference are important in CCC, there are also significant differences between the classic and "green" AZ systems that are discussed.

  8. Coupling Charge Reduction Mass Spectrometry to Liquid Chromatography for Complex Mixture Analysis.

    PubMed

    Stutzman, John R; Crowe, Matthew C; Alexander, James N; Bell, Bruce M; Dunkle, Melissa N

    2016-04-01

    Electrospray ionization (ESI) of solution mixtures often generates complex mass spectra, even following liquid chromatography (LC), due to analyte multiple charging. Multiple charge state distributions can lead to isobaric interferences, mass spectral congestion, and ambiguous ion identification. As a consequence, data interpretation increases in complexity. Several charge reduction mass spectrometry (MS) approaches have been previously developed to reduce the average charge state of gaseous ions; however, all of these techniques have been restricted to direct infusion MS. In this study, synthetic polyols and surfactants separated by liquid chromatography and ionized by positive mode ESI have been subjected to polonium-210 α-particle radiation to reduce the average charge state to singly charged cations prior to mass analysis. LC/MS analysis of 5000 molecular weight poly(ethylene glycol) (PEG5000) generated an average charge state of 5.88+; whereupon, liquid chromatography/electrospray ionization/charge reduction/mass spectrometry (LC/CR/MS) analysis of PEG 5000 generated an average charge state of 1.00+. The PEG5000 results demonstrated a decrease in spectral complexity and enabled facile interpretation. Other complex solution mixtures representing specific MS challenges (i.e., competitive ionization and isobaric ion overlap) were explored and analyzed with LC/CR/MS to demonstrate the benefits of coupling LC to CR/MS. For example, polyol information related to initiator, identity/relative amount of monomer, and estimated molecular weight was characterized in random and triblock ethylene oxide/propylene oxide polyols using LC/CR/MS. LC/CR/MS is a new analytical technique for the analysis of complex mixtures. PMID:26971559

  9. Liquid chromatography/Fourier transform IR spectrometry interface flow cell

    DOEpatents

    Johnson, Charles C.; Taylor, Larry T.

    1986-01-01

    A zero dead volume (ZDV) microbore high performance liquid chromatography (.mu.HPLC)/Fourier transform infrared (FTIR) interface flow cell includes an IR transparent crystal having a small diameter bore therein through which a sample liquid is passed. The interface flow cell further includes a metal holder in combination with a pair of inner, compressible seals for directly coupling the thus configured spectrometric flow cell to the outlet of a .mu.HPLC column end fitting to minimize the transfer volume of the effluents exiting the .mu.HPLC column which exhibit excellent flow characteristics due to the essentially unencumbered, open-flow design. The IR beam passes transverse to the sample flow through the circular bore within the IR transparent crystal, which is preferably comprised of potassium bromide (KBr) or calcium fluoride (CaF.sub.2), so as to minimize interference patterns and vignetting encountered in conventional parallel-plate IR cells. The long IR beam pathlength and lensing effect of the circular cross-section of the sample volume in combination with the refractive index differences between the solvent and the transparent crystal serve to focus the IR beam in enhancing sample detection sensitivity by an order of magnitude.

  10. Liquid chromatography/Fourier transform IR spectrometry interface flow cell

    DOEpatents

    Johnson, C.C.; Taylor, L.T.

    1985-01-04

    A zero dead volume (ZDV) microbore high performance liquid chromatography (..mu.. HPLC)/Fourier transform infrared (FTIR) interface flow cell includes an IR transparent crystal having a small diameter bore therein through which a sample liquid is passed. The interface flow cell further includes a metal holder in combination with a pair of inner, compressible seals for directly coupling the thus configured spectrometric flow cell to the outlet of a ..mu.. HPLC column end fitting to minimize the transfer volume of the effluents exiting the ..mu.. HPLC column which exhibit excellent flow characteristics due to the essentially unencumbered, open-flow design. The IR beam passes transverse to the sample flow through the circular bore within the IR transparent crystal, which is preferably comprised of potassium bromide (KBr) or calcium fluoride (CaF/sub 2/), so as to minimize interference patterns and vignetting encountered in conventional parallel-plate IR cells. The long IR beam pathlength and lensing effect of the circular cross-section of the sample volume in combination with the refractive index differences between the solvent and the transparent crystal serve to focus the IR beam in enhancing sample detection sensitivity by an order of magnitude.

  11. High Performance Liquid Chromatography at -196 °C.

    PubMed

    Motono, Tomohiro; Kitagawa, Shinya; Ohtani, Hajime

    2016-07-01

    Ultralow temperature high-performance liquid chromatography (HPLC) was developed using a liquefied gas as the mobile phase. HPLC separation of low molecular weight alkanes at -196 °C with liquid nitrogen mobile phase was successfully achieved, whereas their GC separation at -196 °C using helium gas mobile phase failed to elute the analytes due to strong adsorption. Prior to the further study of HPLC at -196 °C, the effect of column temperature on the chromatographic behavior was investigated, and it was found that the retention of analytes drastically increased when the column temperature was over the boiling point of the mobile phase. As the study of retention control in HPLC at -196 °C, the mobile phases of nitrogen and methane mixtures were investigated. The addition of methane to the nitrogen mobile phase suppressed the retention of the analytes (tetra-deuterated methane, ethane, and propane), that is, the retention on HPLC at ultralow temperature could be controlled by the mobile phase composition, akin to the typical retention in HPLC. The selectivity toward the n- and iso-alkane in HPLC at -196 °C was altered compared with that in GC separation at room temperature. A significant enhancement of retention of alkanes compared with alkanes were observed in HPLC at -196 °C. PMID:27282809

  12. Determination of doxycycline in chicken fat by liquid chromatography with UV detection and liquid chromatography-tandem mass spectrometry.

    PubMed

    Gajda, Anna; Posyniak, Andrzej; Zmudzki, Jan; Tomczyk, Grzegorz

    2013-06-01

    A sensitive analytical method for determination of doxycycline (DC) residues in chicken fat/fat and skin was developed. The extraction, in the presence of the internal standard (IS) minocycline (MINO), was carried out using solution of oxalic acid (pH 4.0) and ethyl acetate. The samples were cleaned up by solid phase extraction (SPE) procedure using, at first carboxylic acid and then polymeric Strata X cartridges. Chromatographic separation of DC by LC-UV was achieved on a Luna C8 analytical column and for LC-MS/MS analysis Luna C18 column was used. The presented procedures were evaluated according to the Commission Decision 2002/657/EC. Specificity, decision limit (CCα), detection capacity (CCβ), recovery (absolute and relative), precision (repeatability and reproducibility) were determined during validation process. The limit of detection (LOD) was 10μg/kg for LC-UV and 1μg/kg for LC-MS/MS method. The limit of quantitation (LOQ) was 15 and 2μg/kg for LC-UV and LC-MS/MS, respectively. The absolute recovery for the LC-UV and relative recovery for the LC-MS/MS method at 300μg/kg concentration level were 79%; 101% for fat and 82%; 99% for fat and skin, respectively. The developed liquid chromatography with ultraviolet detection (LC-UV) and liquid chromatography tandem mass spectrometry (LC-MS/MS) methods have been applied to quantitative determination of doxycycline (DC) in samples of chicken fat tissue obtained from animals treated with DC.

  13. Liquid chromatography-nuclear magnetic resonance coupling as alternative to liquid chromatography-mass spectrometry hyphenations: curious option or powerful and complementary routine tool?

    PubMed

    Sturm, Sonja; Seger, Christoph

    2012-10-12

    Combining the most powerful separation techniques, i.e. liquid chromatography (LC) or capillary electrophoresis (CE) with a information rich detection system - the mass spectrometer or the nuclear magnetic resonance (NMR) spectrometer - has been pursued for more than three decades. This compilation shall provide an overview of the advantages and limitations of the LC-NMR hyphenation in the light of its most valued application-the unequivocal analyte identification. Especially the post LC trapping of analytes with an in-line solid phase extraction (SPE) device prior to transferring the analyte of interest to the NMR spectrometer (LC-SPE-NMR) proved to be a robust installation allowing a significant cut-down of the amount of analyte needed for the generation of high quality heteronuclear NMR shift correlation data. Different available technical realizations will be discussed and typical application examples from natural product research and from industrial settings will be given.

  14. Determination of descriptors for fragrance compounds by gas chromatography and liquid-liquid partition.

    PubMed

    Karunasekara, Thushara; Poole, Colin F

    2012-04-27

    Retention factors on a minimum of eight stationary phases at various temperatures by gas-liquid chromatography and liquid-liquid partition coefficients for five totally organic biphasic systems were combined to estimate descriptors for 28 fragrance compounds with an emphasis on compounds that are known or potential allergens. The descriptors facilitated the estimation of several properties of biological and environmental interest (sensory irritation threshold, odor detection threshold, nasal pungency threshold, skin permeability from water, skin-water partition coefficients, octanol-water partition coefficients, absorption by air particles, adsorption by diesel soot particles, air-water partition coefficients, and adsorption by film water). The descriptors are suitable for use in the solvation parameter model and facilitate the estimation of a wide range of physicochemical, chromatographic, biological, and environmental properties using existing models.

  15. Identification of New Metabolites of Bacterial Transformation of Indole by Gas Chromatography-Mass Spectrometry and High Performance Liquid Chromatography

    PubMed Central

    Arora, Pankaj Kumar

    2014-01-01

    Arthrobacter sp. SPG transformed indole completely in the presence of an additional carbon source. High performance liquid chromatography and gas chromatography-mass spectrometry detected indole-3-acetic acid, indole-3-glyoxylic acid, and indole-3-aldehyde as biotransformation products. This is the first report of the formation of indole-3-acetic acid, indole-3-glyoxylic acid, and indole-3-aldehyde from indole by any bacterium. PMID:25548566

  16. Determination of maduramicin by liquid chromatography with atomic absorption spectrometric detection.

    PubMed

    Johnson, N A

    1989-01-01

    A liquid chromatograph was interfaced to an atomic absorption spectrometer for the detection and quantitation of maduramicin in feed matrixes at the 1-8 ppm level. Ionophores in general form strong 1:1 products with various metal cations, yielding complexes that are insoluble in water but very soluble in organic solvents. Maduramicin, a carboxylic, polyalcohol, polyether antibiotic, is labeled with the sodium cation and analyzed by atomic absorption spectroscopy (AAS). The lower limit of detection is approximately 100-200 ng maduramicin sodium salt. Feeds containing 1-8 ppm maduramicin are extracted with acetone, the extract is passed through an alumina column, the column is eluted with acetonitrile-water (90 + 10), and the eluate is analyzed for maduramicin by liquid chromatography-AAS after concentration and conversion of maduramicin to the sodium salt. Recoveries of maduramicin averaged 89.5%. Liquid chromatography with AAS detection has been shown to be a sensitive and highly specific technique for the determination of ionophores in general and maduramicin in particular. PMID:2708270

  17. Improvement of mineral oil saturated and aromatic hydrocarbons determination in edible oil by liquid-liquid-gas chromatography with dual detection.

    PubMed

    Zoccali, Mariosimone; Barp, Laura; Beccaria, Marco; Sciarrone, Danilo; Purcaro, Giorgia; Mondello, Luigi

    2016-02-01

    Mineral oils, which are mainly composed of saturated hydrocarbons and aromatic hydrocarbons, are widespread food contaminants. Liquid chromatography coupled to gas chromatography with flame ionization detection represents the method of choice to determine these two families. However, despite the high selectivity of this technique, the presence of olefins (particularly squalene and its isomers) in some samples as in olive oils, does not allow the correct quantification of the mineral oil aromatic hydrocarbons fraction, requiring additional off-line tools to eliminate them. In the present research, a novel on-line liquid chromatography coupled to gas chromatography method is described for the determination of hydrocarbon contamination in edible oils. Two different liquid chromatography columns, namely a silica one (to retain the bulk of the matrix) and a silver-ion one (which better retains the olefins), were coupled in series to obtain the mineral oil aromatic hydrocarbons hump free of interfering peaks. Furthermore, the use of a simultaneous dual detection, flame ionization detector and triple quadrupole mass spectrometer allowed us not only to quantify the mineral oil contamination, but also to evaluate the presence of specific markers (i.e. hopanes) to confirm the petrogenic origin of the contamination.

  18. Improvement of mineral oil saturated and aromatic hydrocarbons determination in edible oil by liquid-liquid-gas chromatography with dual detection.

    PubMed

    Zoccali, Mariosimone; Barp, Laura; Beccaria, Marco; Sciarrone, Danilo; Purcaro, Giorgia; Mondello, Luigi

    2016-02-01

    Mineral oils, which are mainly composed of saturated hydrocarbons and aromatic hydrocarbons, are widespread food contaminants. Liquid chromatography coupled to gas chromatography with flame ionization detection represents the method of choice to determine these two families. However, despite the high selectivity of this technique, the presence of olefins (particularly squalene and its isomers) in some samples as in olive oils, does not allow the correct quantification of the mineral oil aromatic hydrocarbons fraction, requiring additional off-line tools to eliminate them. In the present research, a novel on-line liquid chromatography coupled to gas chromatography method is described for the determination of hydrocarbon contamination in edible oils. Two different liquid chromatography columns, namely a silica one (to retain the bulk of the matrix) and a silver-ion one (which better retains the olefins), were coupled in series to obtain the mineral oil aromatic hydrocarbons hump free of interfering peaks. Furthermore, the use of a simultaneous dual detection, flame ionization detector and triple quadrupole mass spectrometer allowed us not only to quantify the mineral oil contamination, but also to evaluate the presence of specific markers (i.e. hopanes) to confirm the petrogenic origin of the contamination. PMID:26614690

  19. Novel materials and methods for solid-phase extraction and liquid chromatography

    SciTech Connect

    Ambrose, D.

    1997-06-24

    This report contains a general introduction which discusses solid-phase extraction and solid-phase micro-extraction as sample preparation techniques for high-performance liquid chromatography, which is also evaluated in the study. This report also contains the Conclusions section. Four sections have been removed and processed separately: silicalite as a sorbent for solid-phase extraction; a new, high-capacity carboxylic acid functionalized resin for solid-phase extraction; semi-micro solid-phase extraction of organic compounds from aqueous and biological samples; and the high-performance liquid chromatographic determination of drugs and metabolites in human serum and urine using direct injection and a unique molecular sieve.

  20. Reversed-phase High Performance Liquid Chromatography of proteins.

    PubMed

    Josic, Djuro; Kovac, Spomenka

    2010-08-01

    Reversed-phase HPLC (RP-HPLC) is one of most important techniques for protein separations and the method of choice for peptide separation. RP-HPLC has been applied on the nano, micro, and analytical scale, and has also been scaled up for preparative purifications, to large industrial scale. Because of its compatibility with mass spectrometry, RP-HPLC is an indispensable tool in proteomic research. With modern instrumentation and columns, complex mixtures of peptides and proteins can be separated at attomolar levels for further analysis. In addition, preparative RP-HPLC is often used for large-scale purification of proteins. This unit provides protocols for packing and testing a column, protein separation by use of gradient or step elution, desalting of protein solutions, and separation of enzymatic digests before mass spectrometric analyses. A protocol is also provided for cleaning, regenerating, and storing reversed-phase chromatography columns.

  1. Indirect fluorometric detection techniques on thin layer chromatography and effect of ultrasound on gel electrophoresis

    SciTech Connect

    Yinfa, Ma.

    1990-12-10

    Thin-layer chromatography (TLC) is a broadly applicable separation technique. It offers many advantages over high performance liquid chromatography (HPLC), such as easily adapted for two-dimensional separation, for whole-column'' detection and for handling multiple samples, etc. However, due to its draggy development of detection techniques comparing with HPLC, TLC has not received the attention it deserves. Therefore, exploring new detection techniques is very important to the development of TLC. It is the principal of this dissertation to present a new detection method for TLC -- indirect fluorometric detection method. This detection technique is universal sensitive, nondestructive, and simple. This will be described in detail from Sections 1 through Section 5. Section 1 and 3 describe the indirect fluorometric detection of anions and nonelectrolytes in TLC. In Section 2, a detection method for cations based on fluorescence quenching of ethidium bromide is presented. In Section 4, a simple and interesting TLC experiment is designed, three different fluorescence detection principles are used for the determination of caffeine, saccharin and sodium benzoate in beverages. A laser-based indirect fluorometric detection technique in TLC is developed in Section 5. Section 6 is totally different from Sections 1 through 5. An ultrasonic effect on the separation of DNA fragments in agarose gel electrophoresis is investigated. 262 refs.

  2. Highly efficient peptide separations in proteomics Part 1. Unidimensional high performance liquid chromatography.

    PubMed

    Sandra, Koen; Moshir, Mahan; D'hondt, Filip; Verleysen, Katleen; Kas, Koen; Sandra, Pat

    2008-04-15

    Sample complexity and dynamic range constitute enormous challenges in proteome analysis. The back-end technology in typical proteomics platforms, namely mass spectrometry (MS), can only tolerate a certain complexity, has a limited dynamic range per spectrum and is very sensitive towards ion suppression. Therefore, component overlap has to be minimized for successful mass spectrometric analysis and subsequent protein identification and quantification. The present review describes the advances that have been made in liquid-based separation techniques with focus on the recent developments to boost the resolving power. The review is divided in two parts; the first part deals with unidimensional liquid chromatography and the second part with bi- and multidimensional liquid-based separation techniques. Part 1 mainly focuses on reversed-phase HPLC due to the fact that it is and will, in the near future, remain the technique of choice to be hyphenated with MS. The impact of increasing the column length, decreasing the particle diameter, replacing the traditional packed beds by monolithics, amongst others, is described. The review is complemented with data obtained in the laboratories of the authors. PMID:18006394

  3. Simultaneous determination of cyclodol and diprazin by thin layer chromatography and high performance liquid chromatography.

    PubMed

    Makharadze, R; Adeishvili, L; Chelidze, T; Imnadze, N; Nizharadze, N

    2009-11-01

    Ciklodol (trihexyphenidil)--the central and peripheral m-cholinoblocker is currently used with other antipsychotic drugs such as phenotiazines and tricycle antidepressants. For the purpose of simultaneous determination of ciklodol and diprazine, were selected two methods of analysis: Thin Layer Chromatography (TLC) and High Performance Liquid Chromatography (HPLC). During development of TLC method was studied the 10 visualizing system and 24 mobile systems. For individual or simultaneous determination of ciklodol and diprazine were recommended the following solvents' systems: 1. Toluene-acetone-ethanole-25%NH(4)OH (45:45: 7.5:2.5), 2. Hexane-ethyl acetate (15:5), 3. Chloroform-heptene-25%NH(4)OH (16:3:3), 4. Ethylacetate-hexane (10:10), 5. Acetonitrile-metanol (10:10) and 6.Heptene-chloroform-ethanol-25% NH(4)OH (5:10:3:1). As visualizing systems were chosen: Iodine vapors, blacklight (UV254) and reagent of FNP. Reagent of FNP gives colored spot just with diprazine and it is also could be used for separation of both objects in simultaneous analysis. Developed HPLC method of simultaneous determination of ciklodol and diprazine: like mobile phase is recommended: Acetonitril- 0.05M KH(2)PO4 (55:45) (v/v) +H(3)PO(4) (pH3.5), column EC250 x 4.6mm, with solid phase Nucleosil, flow rate 1ml/min, sample volume 40 microl. In given conditions, the retention time of ciklodol is 6.005min and diprazine 7.227min. Developed method of simultaneous determination and separation of ciklodol and diprazine in respective mixtures could be successfully applied as in the pharmaceutical, as well in the chemical-toxicological laboratories.

  4. Unified pH values of liquid chromatography mobile phases.

    PubMed

    Suu, Agnes; Jalukse, Lauri; Liigand, Jaanus; Kruve, Anneli; Himmel, Daniel; Krossing, Ingo; Rosés, Martí; Leito, Ivo

    2015-03-01

    This work introduces a conceptually new approach of measuring pH of mixed-solvent liquid chromatography (LC) mobile phases. Mobile phase pH is very important in LC, but its correct measurement is not straightforward, and all commonly used approaches have deficiencies. The new approach is based on the recently introduced unified pH (pH(abs)) scale, which enables direct comparison of acidities of solutions made in different solvents based on chemical potential of the proton in the solutions. This work represents the first experimental realization of the pH(abs) concept using differential potentiometric measurement for comparison of the chemical potentials of the proton in different solutions (connected by a salt bridge), together with earlier published reference points for obtaining the pH(abs) values (referenced to the gas phase) or pH(abs)(H₂O) values (referenced to the aqueous solution). The liquid junction potentials were estimated in the framework of Izutsu's three-component method. pH(abs) values for a number of common LC and LC-MS mobile phases have been determined. The pH(abs) scale enables for the first time direct comparison of acidities of any LC mobile phases, with different organic additives, different buffer components, etc. A possible experimental protocol of putting this new approach into chromatographic practice has been envisaged and its applicability tested. It has been demonstrated that the ionization behavior of bases (cationic acids) in the mobile phases can be better predicted by using the pH(abs)(H₂O) values and aqueous pKa values than by using the alternative means of expressing mobile phase acidity. Description of the ionization behavior of acids on the basis of pH(abs)(H₂O) values is possible if the change of their pKa values with solvent composition change is taken into account. PMID:25664372

  5. Isopropylammonium Formate as a Mobile Phase Modifier for Liquid Chromatography

    PubMed Central

    Collins, Matthew P.; Zhou, Ling; Camp, Suzanne E.; Danielson, Neil D.

    2012-01-01

    Isopropylammonium formate (IPAF), a new alkylammonium formate (AAF) room temperature ionic liquid, has been synthesized from isopropylamine and formic acid and characterized as an organic solvent mobile phase replacement for reversed-phase liquid chromatography (LC). Characterization of IPAF solvent properties in water such as pH, conductivity, and viscosity, as well as its synthesis, is described. The LC polarity (P′) and the solvent strength (S) parameters are determined to be 6.0 and 2.4, respectively, similar to those same parameters for methanol and acetonitrile. Application of this RTIL is demonstrated as an organic solvent replacement for reversed-phase LC to separate a test mixture of niacinamide, acetophenone and p-nitroaniline. The van Deemter plot profile for several columns of different dimensions, particle size, pore size and stationary phase are compared using an IPAF–water mobile phase. At flow rates above 2 mL/min, on-line mixing of the viscous IPAF with water appears not to be uniform. A flattening of the van Deemter profile is noted for particularly short (50 mm) wide bore (4.6 mm) columns packed with larger particles (10 µm). Small particle longer columns likely facilitated mixing at the beginning of the column generating typical linearly increasing van Deemeter curves. IPAF has been further shown as a function of temperature to be a non-denaturing modifier solvent for the separation of the protein cytochrome c from tryptophan compared to methanol. This is important to show, because the semi-preparative separation of native proteins using AAF mobile phases is the long-term goal of this research program. PMID:22718743

  6. Liquid chromatography of hydrocarbonaeous quaternary amines on cyclodextrin bonded silica

    USGS Publications Warehouse

    Abidi, S.L.

    1986-01-01

    Mixtures of n-alkylbenzyldimethylammonium chloride (ABDAC) were resolved into homologous components by high-performance liquid chromatography (HPLC) with a cyclodextrin-bonded silica stationary phase. With a few exceptions, results from this study are similar to those obtained from traditional reversed-phase HPLC. It was found that the presence of electrolytes in aqueous mobile phases is not a critical factor in determining the success of HPLC separation. Under normal HPLC conditions, a mobile phase consisting of either methanol–water (50:50) or acetonitrile–water (30:70) was employed for obtaining adequate resolution of the quaternary ammonium mixtures. Although the percent organic modifier–water profiles were similar to those in previous studies with these compounds, resolution (R) and selectivity (α) parameters were found to be quite susceptible to changes in the mobile phase solvent composition. The retention behavior of the cationic analytes in the homologous series is consistent with the hydrophobic-interaction concept proposed for the retention mechanism via dominant inclusion complex formation. Several electrolytes were chosen for a study of the counter ion effect on the chromatographic characteristics of ABDAC components. Among the electrolytes examined, the perchlorate ion was found most likely to act as an ion-pairing counter ion for ammonium cations in the HPLC system studied. A correlation study established linear relationships between the chain length of ABDAC and the logarithmic capacity factor (k2). The analytical utility of the HPLC method was demonstrated by the analysis of various unknown mixtures.

  7. Simultaneous determination of sulfaquinoxaline, sulfamethazine and pyrimethamine by liquid chromatography.

    PubMed

    Berzas Nevado, J J; Castañeda Peñalvo, G; Guzmán Bernardo, F J

    2000-02-18

    A liquid chromatography method is described to determine sulfaquinoxaline (SQX), sulfamethazine (SMT), and pyrimethamine (PMT), by using a Kromasil C18 column and a 40 mM NaH2PO4 buffer solution, containing 10 mM NaClO4 (pH 3.0)-acetonitrile (65:35) as mobile phase. The mobile phase flow-rate and sample volume injected were 1.5 ml/min and 20 microl, respectively and the samples were dissolved in the mobile phase. The limits of quantification were found to be about 180 microg/l (3.6 ng) for each compound. The method was applied in veterinary commercial formulations. Analyses were made by means of the standard addition method, whose results were compared with those obtained by preparing "tests" (from the stock solutions) and with those obtained by a capillary electrophoresis method. Both methods showed similar results, and then it was proved that some commercial claimed levels were not in agreement with the obtained results by using our analytical method, as they were in other cases. PMID:10722074

  8. 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.

  9. Determination of saffron quality by high-performance liquid chromatography.

    PubMed

    Valle García-Rodríguez, M; Serrano-Díaz, Jéssica; Tarantilis, Petros A; López-Córcoles, Horacio; Carmona, Manuel; Alonso, Gonzalo L

    2014-08-13

    The aim of this work was to propose a high-performance liquid chromatography with diode array detection (HPLC-DAD) method for determining the three main compounds responsible for determining the quality of saffron (crocetin esters, picrocrocin, and safranal) by preparing an aqueous extract according to the ISO 3632 standard to solve the difficulty that this standard has for aroma and taste determination by ultraviolet-visible spectroscopy. Toward this aim, laboratory-isolated picrocrocin, a safranal standard with a purity of ≥ 88%, trans-crocetin di(β-D-gentiobiosyl) ester (trans-4-GG) and trans-crocetin (β-D-glucosyl)-(β-D-gentiobiosyl) ester (trans-3-Gg) standards, both with a purity of ≥ 99%, and 50 different saffron spice samples from Italy, Iran, Greece, and Spain were used in the intralaboratory validation of the HPLC method. The analytical method proposed was adequate in terms of linearity, selectivity, sensitivity, and accuracy for determining the three foremost parameters that define the quality of saffron using only a saffron solution prepared according to the ISO 3632 standard.

  10. Recent advances of liquid chromatography-(tandem) mass spectrometry in clinical and forensic toxicology - An update.

    PubMed

    Remane, Daniela; Wissenbach, Dirk K; Peters, Frank T

    2016-09-01

    Liquid chromatography (LC) coupled to mass spectrometry (MS) or tandem mass spectrometry (MS/MS) is a well-established and widely used technique in clinical and forensic toxicology as well as doping control especially for quantitative analysis. In recent years, many applications for so-called multi-target screening and/or quantification of drugs, poisons, and or their metabolites in biological matrices have been developed. Such methods have proven particularly useful for analysis of so-called new psychoactive substances that have appeared on recreational drug markets throughout the world. Moreover, the evolvement of high resolution MS techniques and the development of data-independent detection modes have opened new possibilities for applications of LC-(MS/MS) in systematic toxicological screening analysis in the so called general unknown setting. The present paper will provide an overview and discuss these recent developments focusing on the literature published after 2010.

  11. Electrochemically-modulated liquid chromatography (EMLC): Column design, retention processes, and applications

    SciTech Connect

    Ting, E.Y.

    1997-10-08

    This work describes the continued development of a new separation technique, electrochemically-modulated liquid chromatography (EMLC), from column design, retention mechanisms to pharmaceutical applications. The introduction section provides a literature review of the technique as well as a brief overview of the research in each of the chapters. This section is followed by four chapters which investigate the issues of EMLC column design, the retention mechanism of monosubstituted aromatic compounds, and the EMLC-based applications to two important classes of pharmaceutical compounds (i.e., corticosteroids and benzodiazepines). These four sections have been removed to process separately for inclusion on the database. The dissertation concludes with a general summary, a prospectus, and a list of references cited in the General Introduction. 32 refs.

  12. Recent advances of liquid chromatography-(tandem) mass spectrometry in clinical and forensic toxicology - An update.

    PubMed

    Remane, Daniela; Wissenbach, Dirk K; Peters, Frank T

    2016-09-01

    Liquid chromatography (LC) coupled to mass spectrometry (MS) or tandem mass spectrometry (MS/MS) is a well-established and widely used technique in clinical and forensic toxicology as well as doping control especially for quantitative analysis. In recent years, many applications for so-called multi-target screening and/or quantification of drugs, poisons, and or their metabolites in biological matrices have been developed. Such methods have proven particularly useful for analysis of so-called new psychoactive substances that have appeared on recreational drug markets throughout the world. Moreover, the evolvement of high resolution MS techniques and the development of data-independent detection modes have opened new possibilities for applications of LC-(MS/MS) in systematic toxicological screening analysis in the so called general unknown setting. The present paper will provide an overview and discuss these recent developments focusing on the literature published after 2010. PMID:27452180

  13. On-line hyphenation of centrifugal partition chromatography and high pressure liquid chromatography for the fractionation of flavonoids from Hippophaë rhamnoides L. berries.

    PubMed

    Michel, Thomas; Destandau, Emilie; Elfakir, Claire

    2011-09-01

    Centrifugal Partition Chromatography (CPC), a liquid-liquid preparative chromatography using two immiscible solvent systems, benefits from numerous advantages for the separation or purification of synthetic or natural products. This study presents the on-line hyphenation of CPC-Evaporative Light Scattering Detector (CPC-ELSD) with High Performance Liquid Chromatography-UV (HPLC-UV) for the fractionation of flavonols from a solvent-free microwave extract of sea buckthorn (Hippophaë rhamnoides L., Elaeagnaceae) berries. An Arizona G system was used for the fractionation of flavonoids by CPC and a fused core Halo C18 column allowed the on-line analyses of collected fractions by HPLC. The on-line CPC/HPLC procedure allowed the simultaneous fractionation step at preparative scale combined with the HPLC analyses which provide direct fingerprint of collected fractions. Thus the crude extract was simplified and immediate information on the composition of fractions could be obtained. Furthermore, this methodology reduced the time of post-fractionation steps and facilitated identification of main molecules by Mass Spectrometry (MS). Rutin, isorhamnetin-3-O-rutinoside, isorhamnetin-3-O-glucoside, quercetin-3-O-glucoside, isorhamnetin-rhamnoside, quercetin and isorhamnetin were identified. CPC-ELSD/HPLC-UV could be considered as a high-throughput technique for the guided fractionation of bioactive natural products from complex crude extracts.

  14. Electrochemically modulated liquid chromatography: Theoretical investigations and applications from the perspectives of chromatography and interfacial electrochemistry

    SciTech Connect

    Keller, David W.

    2005-01-01

    Electrochemically modulated liquid chromatography (EMLC) employs a conductive material as both a stationary phase for chromatographic separations and as a working electrode for performing electrochemistry experiments. This dual functionality gives EMLC the capacity to manipulate chromatographic separations by changing the potential applied (Eapp) to the stationary phase with respect to an external reference. The ability to monitor retention as a function of Eapp provides a means to chromatographically monitor electrosorption processes at solid-liquid interfaces. In this dissertation, the retention mechanism for EMLC is examined from the perspective of electrical double layer theory and interfacial thermodynamics. From the chromatographic data, it is possible to determine the interfacial excess (Λ) of a solute and changes in interfacial tension (dγ) as a function of both Eapp and the supporting electrolyte concentration. Taken together, these two experimentally manipulated parameters can be examined within the context of the Gibbs adsorption equation to delineate the contribution of a variety of interfacial properties, including the charge of solute on the stationary phase and the potential of zero charge (PZC), to the mechanism behind EMLC-based retention. The chromatographic probing of interfacial phenomena is complemented by electroanalytical experiments that exploit the ability to monitor the electronic current flowing through an EMLC column. Cyclic voltammetry and chronoamperometry of an EMLC column are used to determine the electronic performance characteristics of an EMLC column. An electrochemical flow injection analysis of a column is provided in which the current required to maintain a constant Eapp is monitored and provides a way to examine the influence that acetonitrile and supporting electrolyte composition, flow rate, column backpressure, and ionic strength have on the structure of electrified interfaces.

  15. Preparation of fatty acid methyl esters for gas-liquid chromatography[S

    PubMed Central

    Ichihara, Ken'ichi; Fukubayashi, Yumeto

    2010-01-01

    A convenient method using commercial aqueous concentrated HCl (conc. HCl; 35%, w/w) as an acid catalyst was developed for preparation of fatty acid methyl esters (FAMEs) from sterol esters, triacylglycerols, phospholipids, and FFAs for gas-liquid chromatography (GC). An 8% (w/v) solution of HCl in methanol/water (85:15, v/v) was prepared by diluting 9.7 ml of conc. HCl with 41.5 ml of methanol. Toluene (0.2 ml), methanol (1.5 ml), and the 8% HCl solution (0.3 ml) were added sequentially to the lipid sample. The final HCl concentration was 1.2% (w/v). This solution (2 ml) was incubated at 45°C overnight or heated at 100°C for 1–1.5 h. The amount of FFA formed in the presence of water derived from conc. HCl was estimated to be <1.4%. The yields of FAMEs were >96% for the above lipid classes and were the same as or better than those obtained by saponification/methylation or by acid-catalyzed methanolysis/methylation using commercial anhydrous HCl/methanol. The method developed here could be successfully applied to fatty acid analysis of various lipid samples, including fish oils, vegetable oils, and blood lipids by GC. PMID:19759389

  16. Determination of Aspartame, Caffeine, Saccharin, and Benzoic Acid in Beverages by High Performance Liquid Chromatography.

    ERIC Educational Resources Information Center

    Delaney, Michael F.; And Others

    1985-01-01

    Describes a simple and reliable new quantitative analysis experiment using liquid chromatography for the determinaiton of caffeine, saccharin, and sodium benzoate in beverages. Background information, procedures used, and typical results obtained are provided. (JN)

  17. Preparation of pure microbiological samples for pyrolysis gas-liquid chromatography studies

    NASA Technical Reports Server (NTRS)

    Oxborrow, G. S.; Fields, N. D.; Puleo, J. R.

    1976-01-01

    Bacterial samples were prepared for pyrolysis gas-liquid chromatography using cells grown on membrane filters. Pyrochromatograms were reproducible when cells harvested from the filters were pyrolyzed without being washed.

  18. Qualitative and quantitative determination of ubiquinones by the method of high-efficiency liquid chromatography

    SciTech Connect

    Yanotovskii, M.T.; Mogilevskaya, M.P.; Obol'nikova, E.A.; Kogan, L.M.; Samokhvalov, G.I.

    1986-07-10

    A method has been developed for the qualitative and quantitative determination of ubiquinones CoQ/sub 6/-CoQ/sub 10/, using high-efficiency reversed-phase liquid chromatography. Tocopherol acetate was used as the internal standard.

  19. HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY OF SELECTED ORGANIC PEROXIDES WITH OXIDATIVE AMPEROMETRIC DETECTION

    EPA Science Inventory

    Reversed-phase high-performance liquid chromatography with oxidative amperometric detection was optimized for the determination of several organic peroxides in drinking water under ideal conditions.The determinations were performed under isocratic conditions using acetonitrile an...

  20. Herbal medicine analysis by liquid chromatography/time-of-flight mass spectrometry.

    PubMed

    Zhou, Jian-Liang; Qi, Lian-Wen; Li, Ping

    2009-10-30

    The fact that the effects of herbal medicines (HMs) are brought about by their chemical constituents has created a critical demand for powerful analytical tools performing the chemical analysis to assure their efficacy, safety and quality. Liquid chromatography coupled to mass spectrometry (LC-MS) is an excellent technique to analyze multi-components in complex herbal matrices. Due to its inherent characteristics of accurate mass measurements and high resolution, time-of-flight (TOF) MS is well-suited to this field, especially for qualitative applications. The purpose of this article is to provide an overview on the potential of TOF, including the hybrid quadrupole- and ion trap-TOF (QTOF and IT-TOF), hyphenated to LC for chemical analysis in HMs or HM-treated biological samples. The peculiarities of LC-(Q/IT)TOF-MS for the analysis of HMs are discussed first, including applied stationary phase, mobile-phase selection, accurate mass measurements, fragmentation and selectivity. The final section is devoted to describing the applicability of LC-(Q/IT)TOF-MS to routine analysis of multi-components, including target and non-target (unknown) compounds, in herbal samples, emphasizing both the advantages and limitations of this approach for qualitative and quantitative purposes. The potential and future trends of fast high-performance liquid chromatography (HPLC) (e.g. rapid resolution LC and ultra-performance LC) coupled to (Q)TOF-MS for chemical analysis of HMs are highlighted.

  1. Combining Laser Ablation/Liquid Phase Collection Surface Sampling and High-Performance Liquid Chromatography Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Ovchinnikova, Olga S; Kertesz, Vilmos; Van Berkel, Gary J

    2011-01-01

    This paper describes the coupling of ambient pressure transmission geometry laser ablation with a liquid phase sample collection method for surface sampling and ionization with subsequent mass spectral analysis. A commercially available autosampler was adapted to produce a liquid droplet at the end of the syringe injection needle while in close proximity to the surface to collect the sample plume produced by laser ablation. The sample collection was followed by either flow injection or a high performance liquid chromatography (HPLC) separation of the extracted components and detection with electrospray ionization mass spectrometry (ESI-MS). To illustrate the analytical utility of this coupling, thin films of a commercial ink sample containing rhodamine 6G and of mixed isobaric rhodamine B and 6G dyes on glass microscope slides were analyzed. The flow injection and HPLC/ESI-MS analysis revealed successful laser ablation, capture and, with HPLC, the separation of the two compounds. The ablated circular area was about 70 m in diameter for these experiments. The spatial sampling resolution afforded by the laser ablation, as well as the ability to use sample processing methods like HPLC between the sample collection and ionization steps, makes this combined surface sampling/ionization technique a highly versatile analytical tool.

  2. New methods and materials for solid phase extraction and high performance liquid chromatography

    SciTech Connect

    Dumont, P.J.

    1996-04-23

    This paper describes methods for solid phase extraction and high performance liquid chromatography (HPLC). The following are described: Effects of Resin Sulfonation on the Retention of Polar Organic Compounds in Solid Phase Extraction; Ion-Chromatographic Separation of Alkali Metals In Non-Aqueous Solvents; Cation-Exchange Chromatography in Non-Aqueous Solvents; and Silicalite As a Stationary Phase For HPLC.

  3. Liquid Tunable Microlenses based on MEMS techniques

    PubMed Central

    Zeng, Xuefeng; Jiang, Hongrui

    2013-01-01

    The recent rapid development in microlens technology has provided many opportunities for miniaturized optical systems, and has found a wide range of applications. Of these microlenses, tunable-focus microlenses are of special interest as their focal lengths can be tuned using micro-scale actuators integrated with the lens structure. Realization of such tunable microlens generally relies on the microelectromechanical system (MEMS) technologies. Here, we review the recent progress in tunable liquid microlenses. The underlying physics relevant to these microlenses are first discussed, followed by description of three main categories of tunable microlenses involving MEMS techniques, mechanically driven, electrically driven, and those integrated within microfluidic systems. PMID:24163480

  4. A simple liquid extraction protocol for overcoming the ion suppression of triacylglycerols by phospholipids in liquid chromatography mass spectrometry studies.

    PubMed

    Araujo, Pedro; Tilahun, Ephrem; Breivik, Joar Fjørtoft; Abdulkader, Bashir M; Frøyland, Livar; Zeng, Yingxu

    2016-02-01

    It is well-known that triacylglycerol (TAG) ions are suppressed by phospholipid (PL) ions in regiospecific analysis of TAG by mass spectrometry (MS). Hence, it is essential to remove the PL during sample preparation prior to MS analysis. The present article proposes a cost-effective liquid-liquid extraction (LLE) method to remove PL from TAG in different kinds of biological samples by using methanol, hexane and water. High performance thin layer chromatography confirmed the lack of PL in krill oil and salmon liver samples, submitted to the proposed LLE protocol, and liquid chromatography tandem MS confirmed that the identified TAG ions were highly enhanced after implementing the LLE procedure.

  5. Column liquid chromatography-ultraviolet and column liquid chromatography/mass spectrometry evaluation of stress degradation behavior of escitalopram oxalate.

    PubMed

    Dhaneshwar, Sunil R; Mahadik, Mahadeo V; Kulkarni, Mahesh J

    2009-01-01

    The objective of this work was to study the degradation behavior of escitalopram oxalate under different International Conference on Harmonization (ICH)-recommended stress conditions by column liquid chromatography (LC)-UV and LC/mass spectrometry (LC/MS) and to establish a validated stability-indicating LC assay method. Escitalopram oxalate was subjected to stress conditions of hydrolysis, oxidation, photolysis, and thermal decomposition. Extensive degradation was found to occur in alkaline medium. Mild degradation was observed in acidic and oxidative conditions. Escitalopram oxalate was stable to neutral, photolytic, and thermal stress. Successful separation of the drug from degradation products formed under stress conditions was achieved on a PerfectSil-100 ODS-3 column [C18 (5 microm, 25 cm x 4.6 mm id)] using methanol-0.01 M acetate buffer pH 3.8 adjusted with acetic acid (45 + 55) as the mobile phase. The flow rate was 1 ml/min, and the detection wavelength was 239 nm. The method was validated according to ICH guidelines. Major degradation products formed in hydrolysis and oxidative conditions were isolated, and structural elucidation of degradation products was done by LCIMS and infrared spectrometry studies. The major hydrolysis degradation product was confirmed as 1-(3-dimethylaminopropyl)-1-(4-fluoro- phenyl)-1,3dihydroisobenzofuran-5-carboxylic acid, and the major oxidative degradation product was confirmed as 1-{[3-dimethylamino(oxide)- propyl]-1-(4-fluro-phenyl)}-1,3-dihydro-isobenzofuran- 5-carbonitrile.

  6. Chromatography.

    ERIC Educational Resources Information Center

    Brantley, L. Reed, Sr.; Demanche, Edna L.; Klemm, E. Barbara; Kyselka, Will; Phillips, Edwin A.; Pottenger, Francis M.; Yamamoto, Karen N.; Young, Donald B.

    This booklet presents some activities on chromatography. Directions for preparing leaf pigment extracts using alcohol are given, and paper chromatography and thin-layer chromatography are described as modifications of the basic principles of chromatography. (KHR)

  7. Advanced Capillary Liquid Chromatography-Mass Spectrometry for Proteomics

    SciTech Connect

    Shen, Yufeng; Page, Jason S.; Smith, Richard D.

    2009-02-23

    The liquid chromatography (LC)-mass spectrometric (MS) analysis of peptides has become a routine method for proteomics – the study of the entire complement of proteins e.g., expressed by a cell under a specific set of conditions at a specific time. Mixtures of peptides, such as those generated from enzymatic (e.g., trypsin) digestion of globally recovered proteins (i.e. a proteome), are typically very complex and >100,000 different molecular species may be observable using MS detection [1]. LC separations implemented prior to MS for broad protein identification have three major roles: 1) to isolate individual components or reduce complexity as much as possible, 2) to increase sensitivity by concentrating the components into narrow zones prior to MS, and 3) to eliminate or displace interfering species (e.g., salts and polymers) that may be present in proteomics samples. A desired quality of LC separation can be achieved from the use of either multiple steps of moderate quality separations, or fewer steps of high power separations. The former approach is generally more easily accessible for very high quality separations due to the variety of commercialized LC platforms available, while the latter still often requires considerable developmental efforts (for both columns and instrumentation). In addition to proteomics data quality, other differences between these two approaches include proteomics analysis time and sample consumption (and subsequent analysis costs), as well as direct impact on potential proteomics applications that have special requirements in terms of analysis coverage, sample size, dynamic range, sensitivity, and throughput.

  8. Determination of dalcetrapib by liquid chromatography-tandem mass spectrometry.

    PubMed

    Heinig, Katja; Bucheli, Franz; Kuhlmann, Olaf; Zell, Manfred; Pähler, Axel; Zwanziger, Elke; Gross, Günter; Tardio, Joseph; Ishikawa, Tomohiro; Yamashita, Tomoko

    2012-07-01

    The cholesteryl ester transfer protein modulator dalcetrapib is currently under development for the prevention of dyslipidemia and cardiovascular disease. Dalcetrapib, a thioester, is rapidly hydrolyzed in vivo to the corresponding thiophenol which in turn is further oxidized to the dimer and mixed disulfides (where the thiophenol binds to peptides, proteins and other endogenous thiols). These forms co-exist in an oxidation-reduction equilibrium via the thiol and cannot be stabilized without influencing the equilibrium, hence specific determination of individual components, i.e., in order to distinguish between the free thiol, the disulfide dimer and mixed disulfide adducts, was not pursued for routine analysis. The individual forms were quantified collectively as dalcetrapib-thiol (dal-thiol) after reduction under basic conditions with dithiothreitol to break disulfide bonds and derivatization with N-ethylmaleimide to stabilize the free thiol. The S-methyl and S-glucuronide metabolites were determined simultaneously with dal-thiol with no effect from the derivatization procedure. Column-switching liquid chromatography-tandem mass spectrometry provided a simple, fast and robust method for analysis of human and animal plasma and human urine samples. Addition of the surfactant Tween 80 to urine prevented adsorptive compound loss. The lower limits of quantitation (LLOQ) were 5 ng/mL for dal-thiol, and 5 ng/mL for the S-methyl and 50 ng/mL for the S-glucuronide metabolites. Using stable isotope-labeled internal standards, inter- and intra-assay precisions were each <15% (<20% at LLOQ) and accuracy was between 85 and 115%. Recovery was close to 100%, and no significant matrix effect was observed. PMID:22541249

  9. Performance Evaluation of three Liquid Chromatography Mass Spectrometry Methods for Broad Spectrum Drug Screening

    PubMed Central

    Lynch, Kara L.; Breaud, Autumn R.; Vandenberghe, Hilde; Wu, Alan H. B.; Clarke, William

    2010-01-01

    BACKGROUND Liquid chromatography-mass spectrometry (LC-MS) and tandem LC-MS (LC-MS/MS) are increasingly used in toxicology laboratories as a complementary method to gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-ultraviolet detection (LC-UV) for comprehensive drug screening (CDS). This study was designed to characterize the sensitivity and specificity of three LC-MS(/MS) vendor-supplied methods for targeted CDS and identify the current limitations associated with the use of these technologies. METHODS Five methods for broad spectrum CDS, including LC-UV (REMEDi), full scan GC-MS, LC-MS (ZQ™-Mass Detector with MassLynx™-software), LC-QTRAP-MS/MS (3200-QTRAP® with Cliquid®-software) and LC-LIT-MS/MS (LXQ™ Linear Ion Trap with ToxID™-software) were evaluated based on their ability to detect drugs in 48 patient urine samples. RESULTS The tandem MS methods identified 15% more drugs than the single stage MS or LC-UV methods. Use of two broad spectrum screening methods identified more drugs than any single system alone. False negatives and false positives generated by the LC-MS(/MS) software programs were identified upon manual review of the raw data. CONCLUSIONS The LC-MS/MS methods detected a broader menu of drugs; however, it is essential to establish manual data review criteria for all LC-MS(/MS) drug screening methods. Use of an EI-GC-MS and ESI-LC-MS/MS combination for targeted CDS may be optimal due to the complementary nature of the chromatographic and ionization techniques. PMID:20540936

  10. Using dispersive liquid-liquid microextraction and liquid chromatography for determination of guaifenesin enantiomers in human urine.

    PubMed

    Hatami, Mehdi; Farhadi, Khalil; Abdollahpour, Assem

    2011-11-01

    A simple, rapid, and efficient method, dispersive liquid-liquid microextraction (DLLME) coupled with high-performance liquid chromatography-fluorescence detector, has been developed for the determination of guaifenesin (GUA) enantiomers in human urine samples after an oral dose administration of its syrup formulation. Urine samples were collected during the time intervals 0-2, 2-4, and 4-6 h and concentration and ratio of two enantiomers was determined. The ratio of R-(-) to S-(+) enantiomer concentrations in urine showed an increase with time, with R/S ratios of 0.66 at 2 h and 2.23 at 6 h. For microextraction process, a mixture of extraction solvent (dichloromethane, 100 μL) and dispersive solvent (THF, 1 mL) was rapidly injected into 5.0 mL diluted urine sample for the formation of cloudy solution and extraction of enantiomers into the fine droplets of CH(2)Cl(2). After optimization of HPLC enantioselective conditions, some important parameters, such as the kind and volume of extraction and dispersive solvents, extraction time, temperature, pH, and salt effect were optimized for dispersive liquid-liquid microextraction process. Under the optimum extraction condition, the method yields a linear calibration curve in the concentration range from 10 to 2000 ng/mL for target analytes. LOD was 3.00 ng/mL for both of the enantiomers. PMID:21972192

  11. Identification of unknown impurities in simvastatin substance and tablets by liquid chromatography/tandem mass spectrometry.

    PubMed

    Vuletić, Marko; Cindrić, Mario; Koruznjak, Jasna Dogan

    2005-04-01

    Unknown impurities were detected in simvastatin substance and tablets at a 0.2% level using the liquid chromatography technique with UV (DAD) detection. The impurity structures were elucidated by a direct hyphenation of liquid chromatograph to high-resolution mass spectrometer with electrospray ionisation interface using solutions of formic acid in water and in acetonitrile as the mobile phase. Peak tracking was performed using the column-switching technique. Accurate mass measurements by quadrupole time-of-flight mass spectrometer equipped with lock-spray provided information about elemental composition of intact molecules and fragments of impurities. Measurement accuracy for precursor ions was around 3 ppm and for fragment ions between 4 and 13 ppm. Mass resolving power was around 6500. Deduced molecular formulae for A1, A2 and A3 impurities were C(27)H(44)O(6), C(26)H(43)O(6) and C(26)H(41)O(5), respectively. The structures proposed for all three impurities revealed modifications of simvastatin molecule on the lactone ring. Impurity A1, detected in simvastatin tablets, was identified as ethyl ester, while the impurities A2 and A3, detected in simvastatin substance, were identified as methyl ester and methyl ether of simvastatin. The impurity from tablets was synthesized and its structure confirmed by LC-UV, LC-MS/MS, and NMR techniques.

  12. Determination of metal ions in tea samples using task-specific ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction coupled to liquid chromatography with ultraviolet detection.

    PubMed

    Werner, Justyna

    2016-04-01

    Task-specific ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction was used for the preconcentration of cadmium(II), cobalt(II), and lead(II) ions in tea samples, which were subsequently analyzed by liquid chromatography with UV detection. The proposed method of preconcentration is free of volatile organic compounds, which are often used as extractants and dispersing solvents in classic techniques of microextraction. A task-specific ionic liquid trioctylmethylammonium thiosalicylate was used as an extractant and a chelating agent. Ultrasound was used to disperse the ionic liquid. After microextraction, the phases were separated by centrifugation, and the ionic liquid phase was solubilized in methanol and directly injected into the liquid chromatograph. Selected microextraction parameters, such as the volume of ionic liquid, the pH of the sample, the duration of ultrasound treatment, the speed and time of centrifugation, and the effect of ionic strength, were optimized. Under optimal conditions an enrichment factor of 200 was obtained for each analyte. The limits of detection were 0.002 mg/kg for Cd(II), 0.009 mg/kg for Co(II), and 0.013 mg/kg for Pb(II). The accuracy of the proposed method was evaluated by an analysis of the Certified Reference Materials (INCT-TL-1, INCT-MPH-2) with the recovery values in the range of 90-104%.

  13. [Determination of phenolic and salicylanilide anthelmintics in liquid milk by high performance liquid chromatography].

    PubMed

    Wang, Wei; Huang, Xianhui; Wang, Hui; Yan, Changyan; Kong, Xiangkai

    2013-10-01

    An analytical method for the determination of nitroxynil, oxyclozanide, closantel and rafoxanide in liquid milk by high performance liquid chromatography (HPLC) has been established. The milk sample was extracted with acetonitrile containing 1% (v/v) triethylamine. The supernatant was purified by an anion exchange solid phase extraction column. The analyte was detected by ultraviolet detector after the HPLC separation on a C18 RP column. The mobile phase was composed of acetonitrile-0.02 mol/L ammonium acetate solution with pH 4.0. The linear ranges of the four drugs in the spiked blank milk samples were 5-500 microg/kg, and the correlation coefficients were higher than 0.99. The limits of detection (LOD) were 3 microg/kg, and the limits of quantification (LOQ) were 5 microg/kg. The average recoveries and relative standard deviations (RSDs) of nitroxynil, oxyclozanide, closantel and rafoxanide at the spiked levels of 1/2MRL (maximum residue limit), MRL and 2MRL ranged from 92.20% to 96.13%, 5.55% to 16.30%; 87.40% to 94.74%, 5.40% to 12.21%; 86.97% to 91.09%, 2.67% to 8.17%; and 77.86% to 95.36%, 5.02% to 13.15% respectively. The method is simple and sensitive for the quantification of phenolic and salicylanilide anthelmintics in liquid milk.

  14. Evaluation of a silicon oxynitride hydrophilic interaction liquid chromatography column in saccharide and glycoside separations.

    PubMed

    Wan, Huihui; Sheng, Qianying; Zhong, Hongmin; Guo, Xiujie; Fu, Qing; Liu, Yanfang; Xue, Xingya; Liang, Xinmiao

    2015-05-01

    The retention characteristics of a silicon oxynitride stationary phase for carbohydrate separation were studied in hydrophilic interaction chromatography mode. Four saccharides including mono-, di-, and trisaccharides were employed to investigate the effects of water content and buffer concentration in the mobile phase on hydrophilic interaction liquid chromatography retention. For the tested saccharides, the silicon oxynitride column demonstrated excellent performance in terms of separation efficiency, hydrophilicity, and interesting separation selectivity for carbohydrates compared to the bare silica stationary phase. Finally, the silicon oxynitride hydrophilic interaction liquid chromatography column was employed in the separation of complex samples of fructooligosaccharides, saponins, and steviol glycoside from natural products. The resulting chromatograms demonstrated good separation efficiency and longer retention compared with silica, which further confirmed the advantages and potential application of silicon oxynitride stationary phase for hydrophilic interaction liquid chromatography separation.

  15. Application of Pre-Column Labeling Liquid Chromatography for Canine Plasma-Free Amino Acid Analysis

    PubMed Central

    Azuma, Kazuo; Hirao, Yoshiko; Hayakawa, Yoshihiro; Murahata, Yusuke; Osaki, Tomohiro; Tsuka, Takeshi; Imagawa, Tomohiro; Okamoto, Yoshiharu; Ito, Norihiko

    2016-01-01

    Plasma-free amino acid (PFAA) levels are a useful metric for diagnosing cancer and providing a prognosis. However, the use of analysis of PFAA levels has been limited in the veterinary medicine field. We addressed the application of liquid chromatography (LC) using a pre-column labeling technique for analysis of canine PFAA levels. This method significantly shortened the analysis time relative to conventional methods. No diurnal fluctuations were detected at 9:00 AM in most PFAA levels, and food intake increased the levels of some PFAAs, including valine, leucine, tyrosine, phenylalanine, and proline. These results indicate that LC with pre-column labeling is useful for measuring canine PFAA levels, for which time of day and interval after food intake must be taken into consideration. PMID:26771650

  16. Detailed molecular characterization of castor oil ethoxylates by liquid chromatography multistage mass spectrometry.

    PubMed

    Nasioudis, Andreas; van Velde, Jan W; Heeren, Ron M A; van den Brink, Oscar F

    2011-10-01

    The molecular characterization of castor oil ethoxylates (CASEOs) was studied by reverse-phase liquid chromatography (RPLC) mass spectrometry (MS) and multistage mass spectrometry (MS(n)). The developed RPLC method allowed the separation of the various CASEO components, and especially, the baseline separation of multiple nominal isobars (same nominal mass) and isomers (same exact mass). MS and MS(n) were used for the determination and structure elucidation of various structures and for the discrimination of the isobars and isomers. Different ionization techniques and adduct ions were also tested for optimization of the MS detection and the MS(n) fragmentation. A unique fragmentation pathway of ricinoleic acid is proposed, which can be used as a marker of the polymerization process and the topology of ethoxylation in the CASEO. In addition, characteristic neutral losses of ricinoleic acid reveal its (terminal or internal) position in the molecule.

  17. Isolation and purification of glycoconjugates from complex biological sources by recycling high-performance liquid chromatography.

    PubMed

    Alley, William R; Mann, Benjamin F; Hruska, Vlastimil; Novotny, Milos V

    2013-11-01

    Among of the most urgent needs of the glycobiology community is to generate libraries of pure carbohydrate standards. While many oligosaccharides have recently been synthesized, some glycans of biomedical importance are still missing in existing collections or are available in only limited amounts. To address this need, we demonstrate the use of the relatively unexplored technique of recycling high-performance liquid chromatography (R-HPLC) to isolate and purify glycoconjugates from several natural sources. We were able to routinely achieve purities greater than 98%. In several cases, we were able to obtain isomerically pure substances, particularly for glycans with different positional isomerism. These purified substances can then be used in different analytical applications, for example, as standards for mass spectrometry (MS) and capillary-based separations. Moreover, using a bifunctional aromatic amine, the same derivatization agent can be used to enable UV detection of oligosaccharides during their purification and link the isolated molecules to functionalized surfaces and potentially create glycan arrays.

  18. Application of Pre-Column Labeling Liquid Chromatography for Canine Plasma-Free Amino Acid Analysis.

    PubMed

    Azuma, Kazuo; Hirao, Yoshiko; Hayakawa, Yoshihiro; Murahata, Yusuke; Osaki, Tomohiro; Tsuka, Takeshi; Imagawa, Tomohiro; Okamoto, Yoshiharu; Ito, Norihiko

    2016-01-01

    Plasma-free amino acid (PFAA) levels are a useful metric for diagnosing cancer and providing a prognosis. However, the use of analysis of PFAA levels has been limited in the veterinary medicine field. We addressed the application of liquid chromatography (LC) using a pre-column labeling technique for analysis of canine PFAA levels. This method significantly shortened the analysis time relative to conventional methods. No diurnal fluctuations were detected at 9:00 AM in most PFAA levels, and food intake increased the levels of some PFAAs, including valine, leucine, tyrosine, phenylalanine, and proline. These results indicate that LC with pre-column labeling is useful for measuring canine PFAA levels, for which time of day and interval after food intake must be taken into consideration. PMID:26771650

  19. Current applications of liquid chromatography/mass spectrometry in pharmaceutical discovery after a decade of innovation.

    PubMed

    Ackermann, Bradley L; Berna, Michael J; Eckstein, James A; Ott, Lee W; Chaudhary, Ajai K

    2008-01-01

    Current drug discovery involves a highly iterative process pertaining to three core disciplines: biology, chemistry, and drug disposition. For most pharmaceutical companies the path to a drug candidate comprises similar stages: target identification, biological screening, lead generation, lead optimization, and candidate selection. Over the past decade, the overall efficiency of drug discovery has been greatly improved by a single instrumental technique, liquid chromatography/mass spectrometry (LC/MS). Transformed by the commercial introduction of the atmospheric pressure ionization interface in the mid-1990s, LC/MS has expanded into almost every area of drug discovery. In many cases, drug discovery workflow has been changed owing to vastly improved efficiency. This review examines recent trends for these three core disciplines and presents seminal examples where LC/MS has altered the current approach to drug discovery.

  20. Analysis of RNA modifications by liquid chromatography-tandem mass spectrometry.

    PubMed

    Thüring, Kathrin; Schmid, Katharina; Keller, Patrick; Helm, Mark

    2016-09-01

    The analysis of RNA modifications is of high importance in order to address a wide range of biological questions. Therefore, a highly sensitive and accurate method such as liquid chromatography-tandem mass spectrometry (LC-MS/MS) has to be available. By using different LC-MS/MS procedures, it is not only possible to quantify very low amounts of RNA modifications, but also to detect probably unknown modified nucleosides. For these cases the dynamic multiple reaction monitoring and the neutral loss scan are the most common techniques. Here, we provide the whole workflow for analyzing RNA samples regarding their modification content. This includes an equipment list, the preparation of required solutions/enzymes and the creation of an internal standard or nucleoside stocks for internal or external calibration. Furthermore, we describe the preparation of RNA samples for the subsequent LC-MS/MS analysis and the corresponding analysis process. PMID:27020891

  1. Hydrocarbon group type determination in jet fuels by high performance liquid chromatography

    NASA Technical Reports Server (NTRS)

    Antoine, A. C.

    1977-01-01

    Results are given for the analysis of some jet and diesel fuel samples which were prepared from oil shale and coal syncrudes. Thirty-two samples of varying chemical composition and physical properties were obtained. Hydrocarbon types in these samples were determined by fluorescent indicator adsorption (FIA) analysis, and the results from three laboratories are presented and compared. Recently, rapid high performance liquid chromatography (HPLC) methods have been proposed for hydrocarbon group type analysis, with some suggestion for their use as a replacement of the FIA technique. Two of these methods were used to analyze some of the samples, and these results are also presented and compared. Two samples of petroleum-based Jet A fuel are similarly analyzed.

  2. Preparation of highly purified timosaponin AIII from rhizoma anemarrhenae through an enzymatic method combined with preparative liquid chromatography.

    PubMed

    Lu, Lu; Liu, Yanping; Ding, Yue; Hou, Jianwei; Zhang, Yong; Xue, Haiping; Zhang, Tong

    2016-10-01

    Timosaponin AIII (TAIII) exhibits extensive pharmacological activities and has been reported as a potent antitumour agent for various human cancers. In the present study, a potential industrial process for producing TAIII that involves biotransformation directly in the crude extract liquid of rhizoma anemarrhenae (RA) was developed. β-D-glycosidase was used to transform timosaponin BII (TBII) into TAIII, and monofactor experiments were conducted to optimise the enzymolysis conditions. In addition, AB-8 macroporous resin column chromatography, preparative liquid chromatography, and crystallisation technique were applied for yielding TAIII crystals with a purity > 97%. Approximately, 7 g of TAIII with a high purity of > 97% was obtained from 1 kg of RA through this five-step preparation method, which can be used to produce TAIII on a large scale. PMID:27055070

  3. Systematic evaluation of matrix effects in hydrophilic interaction chromatography versus reversed phase liquid chromatography coupled to mass spectrometry.

    PubMed

    Periat, Aurélie; Kohler, Isabelle; Thomas, Aurélien; Nicoli, Raul; Boccard, Julien; Veuthey, Jean-Luc; Schappler, Julie; Guillarme, Davy

    2016-03-25

    Reversed phase liquid chromatography (RPLC) coupled to mass spectrometry (MS) is the gold standard technique in bioanalysis. However, hydrophilic interaction chromatography (HILIC) could represent a viable alternative to RPLC for the analysis of polar and/or ionizable compounds, as it often provides higher MS sensitivity and alternative selectivity. Nevertheless, this technique can be also prone to matrix effects (ME). ME are one of the major issues in quantitative LC-MS bioanalysis. To ensure acceptable method performance (i.e., trueness and precision), a careful evaluation and minimization of ME is required. In the present study, the incidence of ME in HILIC-MS/MS and RPLC-MS/MS was compared for plasma and urine samples using two representative sets of 38 pharmaceutical compounds and 40 doping agents, respectively. The optimal generic chromatographic conditions in terms of selectivity with respect to interfering compounds were established in both chromatographic modes by testing three different stationary phases in each mode with different mobile phase pH. A second step involved the assessment of ME in RPLC and HILIC under the best generic conditions, using the post-extraction addition method. Biological samples were prepared using two different sample pre-treatments, i.e., a non-selective sample clean-up procedure (protein precipitation and simple dilution for plasma and urine samples, respectively) and a selective sample preparation, i.e., solid phase extraction for both matrices. The non-selective pretreatments led to significantly less ME in RPLC vs. HILIC conditions regardless of the matrix. On the contrary, HILIC appeared as a valuable alternative to RPLC for plasma and urine samples treated by a selective sample preparation. Indeed, in the case of selective sample preparation, the compounds influenced by ME were different in HILIC and RPLC, and lower and similar ME occurrence was generally observed in RPLC vs. HILIC for urine and plasma samples

  4. Characterization of synthetic dyes by comprehensive two-dimensional liquid chromatography combining ion-exchange chromatography and fast ion-pair reversed-phase chromatography.

    PubMed

    Pirok, Bob W J; Knip, Jitske; van Bommel, Maarten R; Schoenmakers, Peter J

    2016-03-01

    In the late 19th century, newly invented synthetic dyes rapidly replaced the natural dyes on the market. The characterization of mixtures of these so-called early synthetic dyes is complicated through the occurrence of many impurities and degradation products. Conventional one-dimensional liquid chromatography does not suffice to obtain fingerprints with sufficient resolution and baseline integrity. Comprehensive two-dimensional liquid chromatography (LC×LC) is employed in this study, with ion-exchange chromatography in the first dimension and fast ion-pair liquid chromatography in the second. Retention in the first dimension is largely determined by the number of charges, while the selection of a small ion-pair reagent (tetramethylammonium hydroxide) in the second dimension causes retention to be largely determined by the molecular structure of the dye. As a result, there is a high degree of orthogonality of the two dimensions, similar to the values typically encountered in GC×GC. The proposed LC×LC method shows a theroretical peak capacity of about 2000 in an analysis time of about three hours. Clear, informative fingerprints are obtained that open a way to a more efficient characterization of dyes used in objects of cultural heritage.

  5. Characterization of synthetic dyes by comprehensive two-dimensional liquid chromatography combining ion-exchange chromatography and fast ion-pair reversed-phase chromatography.

    PubMed

    Pirok, Bob W J; Knip, Jitske; van Bommel, Maarten R; Schoenmakers, Peter J

    2016-03-01

    In the late 19th century, newly invented synthetic dyes rapidly replaced the natural dyes on the market. The characterization of mixtures of these so-called early synthetic dyes is complicated through the occurrence of many impurities and degradation products. Conventional one-dimensional liquid chromatography does not suffice to obtain fingerprints with sufficient resolution and baseline integrity. Comprehensive two-dimensional liquid chromatography (LC×LC) is employed in this study, with ion-exchange chromatography in the first dimension and fast ion-pair liquid chromatography in the second. Retention in the first dimension is largely determined by the number of charges, while the selection of a small ion-pair reagent (tetramethylammonium hydroxide) in the second dimension causes retention to be largely determined by the molecular structure of the dye. As a result, there is a high degree of orthogonality of the two dimensions, similar to the values typically encountered in GC×GC. The proposed LC×LC method shows a theroretical peak capacity of about 2000 in an analysis time of about three hours. Clear, informative fingerprints are obtained that open a way to a more efficient characterization of dyes used in objects of cultural heritage. PMID:26868445

  6. Liquid chromatography "on-flow" 1H nuclear magnetic resonance on native glycosphingolipid mixtures together with gas chromatography/mass spectrometry on the released oligosaccharides for screening and characterisation of carbohydrate-based antigens from pig lungs.

    PubMed

    Bäcker, A E; Thorbert, S; Rakotonirainy, O; Hallberg, E C; Olling, A; Gustavsson, M; Samuelsson, B E; Soussi, B

    1999-01-01

    Glycosphingolipids were prepared from pig lung and pooled into two fractions with (i) < or = 3 sugar residues, and (ii) > or = 3 sugar residues. Oligosaccharides were prepared and used for gas chromatography, gas chromatography/mass spectrometry and matrix-assisted laser desorption/ionization mass spectrometry. The glycolipid fractions i and ii were further characterised and purified using a novel method based on high performance liquid chromatography "on-flow" proton nuclear magnetic resonance. The LC "on-flow" NMR technique showed good chromatographic separation and gave NMR spectral information which could be used as guidance for pooling of the separated mixture glycolipids. Conventional 1H NMR, thin layer immunostaining, gas chromatography, gas chromatography/mass spectrometry and matrix-assisted laser desorption/ionization mass spectrometry were used to characterise the glycolipids and to validate LC-NMR spectral data.

  7. Preparation and evaluation of surface-bonded tricationic ionic liquid silica as stationary phases for high-performance liquid chromatography.

    PubMed

    Qiao, Lizhen; Shi, Xianzhe; Lu, Xin; Xu, Guowang

    2015-05-29

    Two tricationic ionic liquids were prepared and then bonded onto the surface of supporting silica materials through "thiol-ene" click chemistry as new stationary phases for high-performance liquid chromatography. The obtained columns of tricationic ionic liquids were evaluated respectively in the reversed-phase liquid chromatography (RPLC) mode and hydrophilic interaction liquid chromatography (HILIC) mode, and possess ideal column efficiency of 80,000 plates/m in the RPLC mode with naphthalene as the test solute. The tricationic ionic liquid stationary phases exhibit good hydrophobic and shape selectivity to hydrophobic compounds, and RPLC retention behavior with multiple interactions. In the HILIC mode, the retention and selectivity were evaluated through the efficient separation of nucleosides and bases as well as flavonoids, and the typical HILIC retention behavior was demonstrated by investigating retention changes of hydrophilic solutes with water volume fraction in mobile phase. The results show that the tricationic ionic liquid columns possess great prospect for applications in analysis of hydrophobic and hydrophilic samples. PMID:25890438

  8. Preparation and evaluation of surface-bonded tricationic ionic liquid silica as stationary phases for high-performance liquid chromatography.

    PubMed

    Qiao, Lizhen; Shi, Xianzhe; Lu, Xin; Xu, Guowang

    2015-05-29

    Two tricationic ionic liquids were prepared and then bonded onto the surface of supporting silica materials through "thiol-ene" click chemistry as new stationary phases for high-performance liquid chromatography. The obtained columns of tricationic ionic liquids were evaluated respectively in the reversed-phase liquid chromatography (RPLC) mode and hydrophilic interaction liquid chromatography (HILIC) mode, and possess ideal column efficiency of 80,000 plates/m in the RPLC mode with naphthalene as the test solute. The tricationic ionic liquid stationary phases exhibit good hydrophobic and shape selectivity to hydrophobic compounds, and RPLC retention behavior with multiple interactions. In the HILIC mode, the retention and selectivity were evaluated through the efficient separation of nucleosides and bases as well as flavonoids, and the typical HILIC retention behavior was demonstrated by investigating retention changes of hydrophilic solutes with water volume fraction in mobile phase. The results show that the tricationic ionic liquid columns possess great prospect for applications in analysis of hydrophobic and hydrophilic samples.

  9. Crosslinked polymeric ionic liquids as solid-phase microextraction sorbent coatings for high performance liquid chromatography.

    PubMed

    Yu, Honglian; Merib, Josias; Anderson, Jared L

    2016-03-18

    Neat crosslinked polymeric ionic liquid (PIL) sorbent coatings for solid-phase microextraction (SPME) compatible with high-performance liquid chromatography (HPLC) are reported for the first time. Six structurally different PILs were crosslinked to nitinol supports and applied for the determination of select pharmaceutical drugs, phenolics, and insecticides. Sampling conditions including sample solution pH, extraction time, desorption solvent, desorption time, and desorption solvent volume were optimized using design of experiment (DOE). The developed PIL sorbent coatings were stable when performing extractions under acidic pH and remained intact in various organic desorption solvents (i.e., methanol, acetonitrile, acetone). The PIL-based sorbent coating polymerized from the IL monomer 1-vinyl-3-(10-hydroxydecyl) imidazolium chloride [VC10OHIM][Cl] and IL crosslinker 1,12-di(3-vinylbenzylimidazolium) dodecane dichloride [(VBIM)2C12] 2[Cl] exhibited superior extraction performance compared to the other studied PILs. The extraction efficiency of pharmaceutical drugs and phenolics increased when the film thickness of the PIL-based sorbent coating was increased while many insecticides were largely unaffected. Satisfactory analytical performance was obtained with limits of detection (LODs) ranging from 0.2 to 2 μg L(-1) for the target analytes. The accuracy of the analytical method was examined by studying the relative recovery of analytes in real water samples, including tap water and lake water, with recoveries varying from 50.2% to 115.9% and from 48.8% to 116.6%, respectively. PMID:26896916

  10. Crosslinked polymeric ionic liquids as solid-phase microextraction sorbent coatings for high performance liquid chromatography.

    PubMed

    Yu, Honglian; Merib, Josias; Anderson, Jared L

    2016-03-18

    Neat crosslinked polymeric ionic liquid (PIL) sorbent coatings for solid-phase microextraction (SPME) compatible with high-performance liquid chromatography (HPLC) are reported for the first time. Six structurally different PILs were crosslinked to nitinol supports and applied for the determination of select pharmaceutical drugs, phenolics, and insecticides. Sampling conditions including sample solution pH, extraction time, desorption solvent, desorption time, and desorption solvent volume were optimized using design of experiment (DOE). The developed PIL sorbent coatings were stable when performing extractions under acidic pH and remained intact in various organic desorption solvents (i.e., methanol, acetonitrile, acetone). The PIL-based sorbent coating polymerized from the IL monomer 1-vinyl-3-(10-hydroxydecyl) imidazolium chloride [VC10OHIM][Cl] and IL crosslinker 1,12-di(3-vinylbenzylimidazolium) dodecane dichloride [(VBIM)2C12] 2[Cl] exhibited superior extraction performance compared to the other studied PILs. The extraction efficiency of pharmaceutical drugs and phenolics increased when the film thickness of the PIL-based sorbent coating was increased while many insecticides were largely unaffected. Satisfactory analytical performance was obtained with limits of detection (LODs) ranging from 0.2 to 2 μg L(-1) for the target analytes. The accuracy of the analytical method was examined by studying the relative recovery of analytes in real water samples, including tap water and lake water, with recoveries varying from 50.2% to 115.9% and from 48.8% to 116.6%, respectively.

  11. Applications of electrochemically-modulated liquid chromatography (EMLC): Separations of aromatic amino acids and polycyclic aromatic hydrocarbons

    SciTech Connect

    Deng, L.

    1998-03-27

    The research in this thesis explores the separation capabilities of a new technique termed electrochemically-modulated liquid chromatography (EMLC). The thesis begins with a general introduction section which provides a literature review of this technique as well as a brief background discussion of the two research projects in each of the next two chapters. The two papers which follow investigate the application of EMLC to the separation of a mixture of aromatic amino acids and of a mixture of polycyclic aromatic hydrocarbons (PAHs). The last section presents general conclusions and summarizes the thesis. References are compiled in the reference section of each chapter. The two papers have been removed for separate processing.

  12. Accelerated solvent extraction combined with dispersive liquid-liquid microextraction before gas chromatography with mass spectrometry for the sensitive determination of phenols in soil samples.

    PubMed

    Xing, Han-Zhu; Wang, Xia; Chen, Xiang-Feng; Wang, Ming-Lin; Zhao, Ru-Song

    2015-05-01

    A method combining accelerated solvent extraction with dispersive liquid-liquid microextraction was developed for the first time as a sample pretreatment for the rapid analysis of phenols (including phenol, m-cresol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol) in soil samples. In the accelerated solvent extraction procedure, water was used as an extraction solvent, and phenols were extracted from soil samples into water. The dispersive liquid-liquid microextraction technique was then performed on the obtained aqueous solution. Important accelerated solvent extraction and dispersive liquid-liquid microextraction parameters were investigated and optimized. Under optimized conditions, the new method provided wide linearity (6.1-3080 ng/g), low limits of detection (0.06-1.83 ng/g), and excellent reproducibility (<10%) for phenols. Four real soil samples were analyzed by the proposed method to assess its applicability. Experimental results showed that the soil samples were free of our target compounds, and average recoveries were in the range of 87.9-110%. These findings indicate that accelerated solvent extraction with dispersive liquid-liquid microextraction as a sample pretreatment procedure coupled with gas chromatography and mass spectrometry is an excellent method for the rapid analysis of trace levels of phenols in environmental soil samples.

  13. Separation of maleic anhydride grafted polypropylene using multidimensional high-temperature liquid chromatography.

    PubMed

    Prabhu, K N; Macko, T; Brüll, R; Remerie, K; Tacx, J; Garg, P; Ginzburg, A

    2016-04-01

    Functionalization addresses a property gap of polyolefins and opens new perspectives due to improved surface properties in applications like composites (e.g., glass fiber reinforced polypropylene) and anti-corrosive coatings for metals. Various techniques have been developed to characterize functionalized polyolefins, yet no analytical approach addressing their chemical heterogeneity exists. Using High Temperature Size Exclusion Chromatography (HT-SEC) coupled to infrared spectroscopy we could show for two model samples of polypropylene grafted maleic anhydride (PP-g-MA), differing in their nominal MA content, that the grafting density increases with decreasing molar mass. Crystallization Analysis Fractionation (CRYSTAF) does not enable to separate these samples according to their composition to the extent required. Yet, when using High Temperature High Performance Liquid Chromatography (HT-HPLC), with either silica gel or Mica as stationary phase and a gradient mobile phase, a deformulation into a grafted and a non-grafted fraction could be achieved. This was confirmed by analyzing the eluted fractions by infrared spectroscopy. Hyphenating the separation according to composition with a separation according to molar mass (HT-HPLC x HT-SEC) enabled for the first time to reveal the bivariate distribution of PP-g-MA with regard to the molar mass and composition. Using on-line infrared detection quantitative information on the compositional and molar mass parameters of the individual fractions could be obtained. PMID:26961914

  14. [Research on the separation of limonoid glucosides by reversed-phase preparative high performance liquid chromatography].

    PubMed

    Tian, Q G; Dai, J; Ding, X L

    2000-03-01

    Obacunone-17-beta-D-glucopyranoside (OG) was isolated from the seeds of Citrus Sinensis Osbeck by using solvent extraction, classical polymer adsorption column separation and weak base anion ion-exchange separation, OG was finally purified by C18 reversed-phase preparative high performance liquid chromatography and was identified by thin-layer chromatography. The purity of OG was analyzed by analytical reversed-phase HPLC. At last the structure of OG was determined by 1H and 13C nuclear magnetic resonance spectrometry (NMR). In this work, the conditions of the reversed-phase preparative HPLC technique to purify limonoid glucosides was optimized. The reversed-phase preparative HPLC on a C18 column with a mobile phase of acidic acetonitrile-water (about 0.2% TFA, V/V) at pH 3 enabled the baseline separation of limonoid glucosides in the extract. The results show that OG is the predominant limonoid glucoside in the seeds of Citrus Sinensis Osbeck and nomilin glucoside is the second one. The results also show that the classical polymer adsorption column separation and weak base anion ion-exchange separation are effective for purifying limonoid glucosides.

  15. Separation of maleic anhydride grafted polypropylene using multidimensional high-temperature liquid chromatography.

    PubMed

    Prabhu, K N; Macko, T; Brüll, R; Remerie, K; Tacx, J; Garg, P; Ginzburg, A

    2016-04-01

    Functionalization addresses a property gap of polyolefins and opens new perspectives due to improved surface properties in applications like composites (e.g., glass fiber reinforced polypropylene) and anti-corrosive coatings for metals. Various techniques have been developed to characterize functionalized polyolefins, yet no analytical approach addressing their chemical heterogeneity exists. Using High Temperature Size Exclusion Chromatography (HT-SEC) coupled to infrared spectroscopy we could show for two model samples of polypropylene grafted maleic anhydride (PP-g-MA), differing in their nominal MA content, that the grafting density increases with decreasing molar mass. Crystallization Analysis Fractionation (CRYSTAF) does not enable to separate these samples according to their composition to the extent required. Yet, when using High Temperature High Performance Liquid Chromatography (HT-HPLC), with either silica gel or Mica as stationary phase and a gradient mobile phase, a deformulation into a grafted and a non-grafted fraction could be achieved. This was confirmed by analyzing the eluted fractions by infrared spectroscopy. Hyphenating the separation according to composition with a separation according to molar mass (HT-HPLC x HT-SEC) enabled for the first time to reveal the bivariate distribution of PP-g-MA with regard to the molar mass and composition. Using on-line infrared detection quantitative information on the compositional and molar mass parameters of the individual fractions could be obtained.

  16. Advanced analytical techniques for the extraction and characterization of plant-derived essential oils by gas chromatography with mass spectrometry.

    PubMed

    Waseem, Rabia; Low, Kah Hin

    2015-02-01

    In recent years, essential oils have received a growing interest because of the positive health effects of their novel characteristics such as antibacterial, antifungal, and antioxidant activities. For the extraction of plant-derived essential oils, there is the need of advanced analytical techniques and innovative methodologies. An exhaustive study of hydrodistillation, supercritical fluid extraction, ultrasound- and microwave-assisted extraction, solid-phase microextraction, pressurized liquid extraction, pressurized hot water extraction, liquid-liquid extraction, liquid-phase microextraction, matrix solid-phase dispersion, and gas chromatography (one- and two-dimensional) hyphenated with mass spectrometry for the extraction through various plant species and analysis of essential oils has been provided in this review. Essential oils are composed of mainly terpenes and terpenoids with low-molecular-weight aromatic and aliphatic constituents that are particularly important for public health.

  17. The bridge between thin layer chromatography-mass spectrometry and high-performance liquid chromatography-mass spectrometry: The realization of liquid thin layer chromatography-mass spectrometry (LTLC-MS).

    PubMed

    Li, Yafeng; Wang, Jianing; Zhan, Lingpeng; Wleklinski, Michael; Wang, Jiyun; Xiong, Caiqiao; Liu, Huihui; Zhou, Yueming; Nie, Zongxiu

    2016-08-19

    The combination of thin layer chromatography (TLC) and mass spectrometry (MS) has been studied for decades, but for most cases MS detection is done after TLC separation is finished. Here, an online simultaneous TLC-MS analysis system, liquid thin layer chromatography-mass spectrometry (LTLC-MS), is developed which successfully synchronize TLC separation process and MS detection process like GC-MS and HPLC-MS do. And there's no need to use specially designed TLC, just regular TLC plates are enough. LTLC-MS method is composed of a newly developed ambient ionization method, glow discharge-matrix assisted infrared desorption ionization (GD-MAIRDI), and forced-flow TLC (FFTLC) technique, which guarantees the MS detection process does not disturb the TLC separation process throughout the whole analysis. The whole LTLC-MS analysis only need two steps and less than 15min. Mixtures as well as the two main components of a pain relief pills have been successfully analyzed by LTLC-MS. This proof of concept study opens up new possibilities of combining TLC with MS, and will further broaden the application abilities of TLC. PMID:27452991

  18. Isolation and purification of six iridoid glycosides from gardenia jasminoides fruit by medium-pressure liquid chromatography combined with macroporous resin chromatography.

    PubMed

    Wang, Yun; Liu, Hui; Shen, Lifeng; Yao, Lan; Ma, Yinlian; Yu, Dingrong; Chen, Jianhong; Li, Puling; Chen, Ying; Zhang, Cun

    2015-12-01

    Gardeniae fructus is one of the most frequently used herbs in traditional Chinese medicine. In the present study, a process for the enrichment of six iridoid glycosides from Gardeniae fructus was developed using medium-pressure liquid chromatography combined with macroporous resin and reversed-phase chromatography. The purities of different fractions from Gardeniae fructus were assessed using quantitative high-performance liquid chromatography. After fractionation using HPD-100 column chromatography, a 30% ethanol fraction was selected based on high-performance liquid chromatography and liquid chromatography with mass spectrometry qualitative analysis to separate and purify. Based on the orientation analysis results, six compounds-deacetyl asperulosidic acid methyl ester, gardenoside, ixoroside, scandoside methyl ester, genipin-1-O-β-d-gentiobioside, and geniposide-were successfully isolated and purified in three to four combined steps from Gardeniae fructus. The purities of these compounds were found by high-performance liquid chromatography analysis to be 97.9, 98.1, 95.5, 96.3, 97.1, and 98.7%, respectively. Moreover, their structures were elucidated by NMR spectroscopy and liquid chromatography with tandem mass spectrometry. The separation process was highly efficient, rapid, and accurate, making it a potential approach for the large-scale production of iridoids in the laboratory and providing several marker compounds for quality control. This procedure may be meaningful for the purification of other natural products used in traditional Chinese medicine. PMID:26768549

  19. Isolation and purification of six iridoid glycosides from gardenia jasminoides fruit by medium-pressure liquid chromatography combined with macroporous resin chromatography.

    PubMed

    Wang, Yun; Liu, Hui; Shen, Lifeng; Yao, Lan; Ma, Yinlian; Yu, Dingrong; Chen, Jianhong; Li, Puling; Chen, Ying; Zhang, Cun

    2015-12-01

    Gardeniae fructus is one of the most frequently used herbs in traditional Chinese medicine. In the present study, a process for the enrichment of six iridoid glycosides from Gardeniae fructus was developed using medium-pressure liquid chromatography combined with macroporous resin and reversed-phase chromatography. The purities of different fractions from Gardeniae fructus were assessed using quantitative high-performance liquid chromatography. After fractionation using HPD-100 column chromatography, a 30% ethanol fraction was selected based on high-performance liquid chromatography and liquid chromatography with mass spectrometry qualitative analysis to separate and purify. Based on the orientation analysis results, six compounds-deacetyl asperulosidic acid methyl ester, gardenoside, ixoroside, scandoside methyl ester, genipin-1-O-β-d-gentiobioside, and geniposide-were successfully isolated and purified in three to four combined steps from Gardeniae fructus. The purities of these compounds were found by high-performance liquid chromatography analysis to be 97.9, 98.1, 95.5, 96.3, 97.1, and 98.7%, respectively. Moreover, their structures were elucidated by NMR spectroscopy and liquid chromatography with tandem mass spectrometry. The separation process was highly efficient, rapid, and accurate, making it a potential approach for the large-scale production of iridoids in the laboratory and providing several marker compounds for quality control. This procedure may be meaningful for the purification of other natural products used in traditional Chinese medicine.

  20. Speciation analysis of mercury in water samples using dispersive liquid-liquid microextraction combined with high-performance liquid chromatography.

    PubMed

    Gao, Zhongben; Ma, Xiaoguo

    2011-09-19

    A novel approach for preconcentration and speciation analysis of trace amount of mercury from water samples was proposed by dispersive liquid-liquid microextraction (DLLME) coupled to high performance liquid chromatography with diode array detection (HPLC-DAD). Mercury species (Hg(2+), methylmercury (MeHg(+)) and phenylmercury (PhHg(+))) were complexed with dithizone (DZ) to form hydrophobic chelates and then extracted into the fine drops of extraction solvent dispersed in the aqueous sample by dispersive solvent. After extraction, the sedimented phase was analyzed by HPLC-DAD. Some important parameters affecting the DLLME such as extraction solvent and dispersive solvent type and volume, concentration of dithizone solution, sample pH, extraction time and salt effect were investigated. Ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM][PF(6)]) was found to be a suitable extractant for the chelates. Under the optimized conditions (extraction solvent: 70 μL of ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM][PF(6)]); dispersive solvent: 0.75 mL of methanol containing dithizone (0.02%, m/v); pH: 4; extraction time: 5 min; and without salt addition), the limits of detection for Hg(2+), MeHg(+) and PhHg(+) were 0.32, 0.96 and 1.91 μg L(-1) (SN(-1)=3) respectively, and the relative standard deviation (RSD) was between 4.1 and 7.3% (n=5). Three real water samples (tap water, river water and lake water) spiked with mercury species were detected by the developed method, and the relative recoveries obtained for Hg(2+), MeHg(+) and PhHg(+) were 89.6-101.3%, 85.6-102.0% and 81.3-97.6%, respectively. PMID:21819859

  1. Analysis of small carbohydrates in several bioactive botanicals by gas chromatography with mass spectrometry and liquid chromatography with tandem mass spectrometry.

    PubMed

    Moldoveanu, Serban; Scott, Wayne; Zhu, Jeff

    2015-11-01

    Bioactive botanicals contain natural compounds with specific biological activity, such as antibacterial, antioxidant, immune stimulating, and taste improving. A full characterization of the chemical composition of these botanicals is frequently necessary. A study of small carbohydrates from the plant materials of 18 bioactive botanicals is further described. The study presents the identification of the carbohydrate using a gas chromatographic-mass spectrometric analysis that allows detection of molecules as large as maltotetraose, after changing them into trimethylsilyl derivatives. A number of carbohydrates in the plant (fructose, glucose, mannose, sucrose, maltose, xylose, sorbitol, and myo-, chiro-, and scyllo-inositols) were quantitated using a novel liquid chromatography with tandem mass spectrometric technique. Both techniques involved new method developments. The gas chromatography with mass spectrometric analysis involved derivatization and separation on a Rxi(®)-5Sil MS column with H2 as a carrier gas. The liquid chromatographic separation was obtained using a hydrophilic interaction type column, YMC-PAC Polyamine II. The tandem mass spectrometer used an electrospray ionization source in multiple reaction monitoring positive ion mode with the detection of the adducts of the carbohydrates with Cs(+) ions. The validated quantitative procedure showed excellent precision and accuracy allowing the analysis in a wide range of concentrations of the analytes. PMID:26315495

  2. Analysis of small carbohydrates in several bioactive botanicals by gas chromatography with mass spectrometry and liquid chromatography with tandem mass spectrometry.

    PubMed

    Moldoveanu, Serban; Scott, Wayne; Zhu, Jeff

    2015-11-01

    Bioactive botanicals contain natural compounds with specific biological activity, such as antibacterial, antioxidant, immune stimulating, and taste improving. A full characterization of the chemical composition of these botanicals is frequently necessary. A study of small carbohydrates from the plant materials of 18 bioactive botanicals is further described. The study presents the identification of the carbohydrate using a gas chromatographic-mass spectrometric analysis that allows detection of molecules as large as maltotetraose, after changing them into trimethylsilyl derivatives. A number of carbohydrates in the plant (fructose, glucose, mannose, sucrose, maltose, xylose, sorbitol, and myo-, chiro-, and scyllo-inositols) were quantitated using a novel liquid chromatography with tandem mass spectrometric technique. Both techniques involved new method developments. The gas chromatography with mass spectrometric analysis involved derivatization and separation on a Rxi(®)-5Sil MS column with H2 as a carrier gas. The liquid chromatographic separation was obtained using a hydrophilic interaction type column, YMC-PAC Polyamine II. The tandem mass spectrometer used an electrospray ionization source in multiple reaction monitoring positive ion mode with the detection of the adducts of the carbohydrates with Cs(+) ions. The validated quantitative procedure showed excellent precision and accuracy allowing the analysis in a wide range of concentrations of the analytes.

  3. Pipette vial dispersive liquid-liquid microextraction combined with high-performance liquid chromatography for the determination of benzoylurea insecticide in fruit juice.

    PubMed

    Xi, Xuefei; Yang, Miyi; Shen, Ganni; Wu, Xiaoling; Lu, Runhua; Zhou, Wenfeng; Zhang, Sanbing; Gao, Haixiang

    2016-01-01

    A simple, sensitive, and efficient method of using a pipette vial to perform dispersive liquid-liquid microextraction based on the solidification of floating organic droplets was coupled with high-performance liquid chromatography (HPLC) and a diode array detector for the preconcentration and analysis of four benzoylurea insecticides in fruit juice. In this method, 1-dodecanol was used as an extractant, and a snipped pipette was used as an experimental vial to simplify the procedure of collecting and separating solidified extractant. The experimental parameters were optimized using a Plackett-Burman design and one-factor-at-a-time method. Under the optimal conditions in the water model, the limits of detection for analytes varied from 0.03 to 0.28 μg/L, and the enrichment factors ranged from 147 to 206. Linearity was achieved for diflubenzuron and flufenoxuron in a range of 0.5-500 μg/L, for hexaflumuron in a range of 1-500 μg/L, and for triflumuron in a range of 5-500 μg/L. The correlation coefficients for the analytes ranged from 0.9986 to 0.9994 with recoveries of 91.4-110.9%. Finally, the developed technique was successfully applied to fruit juice samples with acceptable results. The relative standard deviations of the analytes at two spiking levels (50 and 200 μg/L) varied between 0.2 and 4.5%. PMID:26526571

  4. Combination of saponification and dispersive liquid-liquid microextraction for the determination of tocopherols and tocotrienols in cereals by reversed-phase high-performance liquid chromatography.

    PubMed

    Shammugasamy, Balakrishnan; Ramakrishnan, Yogeshini; Ghazali, Hasanah M; Muhammad, Kharidah

    2013-07-26

    A simple sample preparation technique coupled with reversed-phase high-performance liquid chromatography was developed for the determination of tocopherols and tocotrienols in cereals. The sample preparation procedure involved a small-scale hydrolysis of 0.5g cereal sample by saponification, followed by the extraction and concentration of tocopherols and tocotrienols from saponified extract using dispersive liquid-liquid microextraction (DLLME). Parameters affecting the DLLME performance were optimized to achieve the highest extraction efficiency and the performance of the developed DLLME method was evaluated. Good linearity was observed over the range assayed (0.031-4.0μg/mL) with regression coefficients greater than 0.9989 for all tocopherols and tocotrienols. Limits of detection and enrichment factors ranged from 0.01 to 0.11μg/mL and 50 to 73, respectively. Intra- and inter-day precision were lower than 8.9% and the recoveries were around 85.5-116.6% for all tocopherols and tocotrienols. The developed DLLME method was successfully applied to cereals: rice, barley, oat, wheat, corn and millet. This new sample preparation approach represents an inexpensive, rapid, simple and precise sample cleanup and concentration method for the determination of tocopherols and tocotrienols in cereals.

  5. Dispersive Liquid-Liquid Microextraction Combined with Ultrahigh Performance Liquid Chromatography/Tandem Mass Spectrometry for Determination of Organophosphate Esters in Aqueous Samples

    PubMed Central

    Luo, Haiying; Xian, Yanping; Guo, Xindong; Luo, Donghui; Lu, Yujing; Yang, Bao

    2014-01-01

    A new technique was established to identify eight organophosphate esters (OPEs) in this work. It utilised dispersive liquid-liquid microextraction in combination with ultrahigh performance liquid chromatography/tandem mass spectrometry. The type and volume of extraction solvents, dispersion agent, and amount of NaCl were optimized. The target analytes were detected in the range of 1.0–200 µg/L with correlation coefficients ranging from 0.9982 to 0.9998, and the detection limits of the analytes were ranged from 0.02 to 0.07 µg/L (S/N = 3). The feasibility of this method was demonstrated by identifying OPEs in aqueous samples that exhibited spiked recoveries, which ranged between 48.7% and 58.3% for triethyl phosphate (TEP) as well as between 85.9% and 113% for the other OPEs. The precision was ranged from 3.2% to 9.3% (n = 6), and the interprecision was ranged from 2.6% to 12.3% (n = 5). Only 2 of the 12 selected samples were tested to be positive for OPEs, and the total concentrations of OPEs in them were 1.1 and 1.6 µg/L, respectively. This method was confirmed to be simple, fast, and accurate for identifying OPEs in aqueous samples. PMID:24616613

  6. Vortex-assisted liquid-liquid microextraction coupled with high performance liquid chromatography for the determination of furfurals and patulin in fruit juices.

    PubMed

    Abu-Bakar, Nur-Bahiyah; Makahleh, Ahmad; Saad, Bahruddin

    2014-03-01

    A fast and simple solvent microextraction technique using salting out-vortex-assisted liquid-liquid microextraction (salting out-VALLME) was developed for the extraction of furfurals (2-furfural (2-F), 3-furfural (3-F), 5-methylfurfural (5-MF) and 5-hydroxymethylfurfural (5-HMF)) and patulin (PAT) in fruit juice samples. The optimum extraction conditions for 5 mL sample were: extraction solvent, 1-hexanol; volume of extractant, 200 µL; vortex time, 45 s; salt addition, 20%. The simultaneous determination of the furfurals and PAT were investigated using high performance liquid chromatography coupled with diode array detector (HPLC-DAD). The separation was performed using ODS Hypersil C18 column (4.6 mm i.d × 250 mm, 5 μm) under gradient elution. The detection wavelengths used for all compounds were 280 nm except for 3-F (210 nm). The furfurals and PAT were successfully separated in less than 9 min. Good linearities (r(2)>0.99) were obtained within the range 1-5000 μg L(-1) for all compounds except for 3-F (10-5000 µg L(-1)) and PAT (0.5-100 μg L(-1)). The limits of detection (0.28-3.2 µg L(-1)) were estimated at S/N ratio of 3. The validated salting out-VALLME-HPLC method was applied for the analysis of furfurals and PAT in fruit juice samples (apple, mango and grape).

  7. Simultaneous determination of six synthetic phenolic antioxidants in edible oils using dispersive liquid-liquid microextraction followed by high-performance liquid chromatography with diode array detection.

    PubMed

    Xu, Shuangjiao; Liu, Liangliang; Wang, Yanqin; Zhou, Dayun; Kuang, Meng; Fang, Dan; Yang, Weihua; Wei, Shoujun; Xiao, Aiping; Ma, Lei

    2016-08-01

    A simple, rapid, organic-solvent- and sample-saving pretreatment technique, called dispersive liquid-liquid microextraction, was developed for the determination of six synthetic phenolic antioxidants from edible oils before high-performance liquid chromatography with diode array detection. The entire procedure was composed of a two-step microextraction and a centrifugal process and could be finished in about 5 min, only consuming only 25 mg of sample and 1 mL of the organic solvent for each extraction. The influences of several important parameters on the microextraction efficiency were thoroughly investigated. Recovery assays for oil samples were spiked at three concentration levels, 50, 100 and 200 mg/kg, and provided recoveries in the 86.3-102.5% range with a relative standard deviation below 3.5%. The intra-day and inter-day precisions for the analysis were less than 3.8%. The proposed method was successfully applied for the determination of synthetic phenolic antioxidants in different oil samples, and satisfactory results were obtained. Thus, the developed method represents a viable alternative for the quality control of synthetic phenolic antioxidant concentrations in edible oils. PMID:27334034

  8. Ion pair-based dispersive liquid-liquid microextraction followed by high performance liquid chromatography as a new method for determining five folate derivatives in foodstuffs.

    PubMed

    Nojavan, Yones; Kamankesh, Marzieh; Shahraz, Farzaneh; Hashemi, Maryam; Mohammadi, Abdorreza

    2015-05-01

    A novel technique for simultaneous determination of five folate derivatives in various food matrices was developed by ion pair-based dispersive liquid-liquid microextraction (IP-DLLME) combined with high-performance liquid chromatography (HPLC). In the proposed method, N-methyl-N,N-dioctyloctan-1-ammonium chloride (aliquat-336) was used as an ion-pair reagent. Effective variables of microextraction process were optimized. Under optimum conditions, the method yielded a linear calibration curve ranging from 1-200 ng g(-1) with correlation coefficients (r(2)) higher than 0.98. The relative standard deviation for the seven analyses was 5.2-7.4%. Enrichment factors for the five folates ranged between 108-135. Limits of detection were 2-4.1 ng g(-1). A comparison of this method with other methods described that the new proposed method is rapid and accurate, and gives very good enrichment factors and detection limits for determining five folate derivatives. The newly developed method was successfully applied for the determination of five folate derivatives in wheat flour, egg yolk and orange juice samples.

  9. Pipette vial dispersive liquid-liquid microextraction combined with high-performance liquid chromatography for the determination of benzoylurea insecticide in fruit juice.

    PubMed

    Xi, Xuefei; Yang, Miyi; Shen, Ganni; Wu, Xiaoling; Lu, Runhua; Zhou, Wenfeng; Zhang, Sanbing; Gao, Haixiang

    2016-01-01

    A simple, sensitive, and efficient method of using a pipette vial to perform dispersive liquid-liquid microextraction based on the solidification of floating organic droplets was coupled with high-performance liquid chromatography (HPLC) and a diode array detector for the preconcentration and analysis of four benzoylurea insecticides in fruit juice. In this method, 1-dodecanol was used as an extractant, and a snipped pipette was used as an experimental vial to simplify the procedure of collecting and separating solidified extractant. The experimental parameters were optimized using a Plackett-Burman design and one-factor-at-a-time method. Under the optimal conditions in the water model, the limits of detection for analytes varied from 0.03 to 0.28 μg/L, and the enrichment factors ranged from 147 to 206. Linearity was achieved for diflubenzuron and flufenoxuron in a range of 0.5-500 μg/L, for hexaflumuron in a range of 1-500 μg/L, and for triflumuron in a range of 5-500 μg/L. The correlation coefficients for the analytes ranged from 0.9986 to 0.9994 with recoveries of 91.4-110.9%. Finally, the developed technique was successfully applied to fruit juice samples with acceptable results. The relative standard deviations of the analytes at two spiking levels (50 and 200 μg/L) varied between 0.2 and 4.5%.

  10. Simultaneous determination of six synthetic phenolic antioxidants in edible oils using dispersive liquid-liquid microextraction followed by high-performance liquid chromatography with diode array detection.

    PubMed

    Xu, Shuangjiao; Liu, Liangliang; Wang, Yanqin; Zhou, Dayun; Kuang, Meng; Fang, Dan; Yang, Weihua; Wei, Shoujun; Xiao, Aiping; Ma, Lei

    2016-08-01

    A simple, rapid, organic-solvent- and sample-saving pretreatment technique, called dispersive liquid-liquid microextraction, was developed for the determination of six synthetic phenolic antioxidants from edible oils before high-performance liquid chromatography with diode array detection. The entire procedure was composed of a two-step microextraction and a centrifugal process and could be finished in about 5 min, only consuming only 25 mg of sample and 1 mL of the organic solvent for each extraction. The influences of several important parameters on the microextraction efficiency were thoroughly investigated. Recovery assays for oil samples were spiked at three concentration levels, 50, 100 and 200 mg/kg, and provided recoveries in the 86.3-102.5% range with a relative standard deviation below 3.5%. The intra-day and inter-day precisions for the analysis were less than 3.8%. The proposed method was successfully applied for the determination of synthetic phenolic antioxidants in different oil samples, and satisfactory results were obtained. Thus, the developed method represents a viable alternative for the quality control of synthetic phenolic antioxidant concentrations in edible oils.

  11. CRC handbook of chromatography

    SciTech Connect

    Qureshi, M.

    1986-01-01

    This book provides technology for routine analysis or developing new methods of chromatography or organic materials. In this book Section 1 presents the principles, techniques, quantitative determinations and detection methods used in chromatographic analysis. In the major part of the book, Section 2 summarizes data in voluminous tabular/graphic form on paper, thin layer, liquid and gas chromatography. Section 3 lists important books on electrophoreses, gel permeation chromatography, and ion exchange, in addition to the other forms of chromatography.

  12. Use of Chromatography Techniques to Separate a Mixture of Substances

    ERIC Educational Resources Information Center

    Donaldson, W.

    1976-01-01

    Explains the separation of the constituents of mixtures on one piece of chromatography paper. The example presented involves a vitamin C tablet, a disprin tablet, and a glucose tablet. Outlined are two methods for separating the constituents. (GS)

  13. Determination of eight synthetic dyes in foodstuffs by green liquid chromatography.

    PubMed

    Hajimahmoodi, Mannan; Afsharimanesh, Mahdi; Moghaddam, Ghazaleh; Sadeghi, Naficeh; Oveisi, Mohammad Reza; Jannat, Behrooz; Pirhadi, Elham; Zamani Mazdeh, Fatemeh; Kanan, Hossein

    2013-01-01

    Eight synthetic food colours were analysed by green liquid chromatography. Green liquid chromatography is an environmentally friendly technique which does not use organic solvents in the extraction procedure or in the chromatographic method. Analysis was carried out for the following colours: tartrazine (E102), indigotine (E132), Quinoline Yellow (E104), Ponceau 4R (E124), Sunset Yellow (E110), Brilliant Blue (E133), Allura Red (E129) and carmoisine (E122) in four different foods: cookies, coloured rice, saffron and fruit juice. The method was performed on an Eurospher-100 C8 (5 μm, 4.6 × 250 mm) column with ultraviolet (UV)-VIS detection and validated by determining the calibration lines, measurement of recovery, precision, and limits of quantification and detection (LODs and LOQs). LOD ranged from 0.04 mg kg⁻¹ for E102 to 1.00 mg kg⁻¹ for E122; LOQ ranged from 0.06 mg kg⁻¹ for E102 to 1.12 mg kg⁻¹ for E122. The levels of colours in foods were compared with Iranian National Standards, but only 7.5% of cookies, 30% of coloured rice, 8% of saffron and 12% of juice samples were in compliance with these standards. Tartrazine is prohibited in Iran, but it was found as the most prevalent food colour in the samples analysed. The results of these tests confirmed that HPLC avoiding the use of organic solvents is a suitable method and can be used for quantitative analyses or screening of food samples for synthetic food colours.

  14. POLAR ORGANIC CHEMICAL INTEGRATIVE SAMPLING AND LIQUID CHROMATOGRAPHY-ELECTROSPRAY/ION-TRAP MASS SPECTROMETRY FOR ASSESSING SELECTED PRESCRIPTION AND ILLICIT DRUGS IN TREATED SEWAGE EFFLUENTS

    EPA Science Inventory

    The purpose of the research presented in this paper is two-fold: (1) to demonstrate the 4 coupling of two state-of-the-art techniques: a time-weighted polar organic integrative sampler (POCIS) and micro-liquid chromatography-electrospray/ion trap mass spectrometry (u-LC-6 ES/ITMS...

  15. Monodisperse microbeads of hypercrosslinked polystyrene for liquid and supercritical fluid chromatography

    NASA Astrophysics Data System (ADS)

    Tsyurupa, M. P.; Blinnikova, Z. K.; Il'in, M. M.; Davankov, V. A.; Parenago, O. O.; Pokrovskii, O. I.; Usovich, O. I.

    2015-11-01

    Monodisperse styrene-divinylbenzene (1 wt %) copolymer microbeads are obtained via the elaborate method of high-productivity precipitation polymerization. The crosslinking of this copolymer with chloromethyl methyl ether in the presence of Friedel-Crafts catalyst yields porous hypercrosslinked polymers with degrees of crosslinking that range from 200 to 500%. Microbead sorbents are shown to be suited for selective stationary phases for high-performance liquid chromatography and supercritical fluid chromatography.

  16. Ionic liquid-based aqueous two-phase system, a sample pretreatment procedure prior to high-performance liquid chromatography of opium alkaloids.

    PubMed

    Li, Shehong; He, Chiyang; Liu, Huwei; Li, Kean; Liu, Feng

    2005-11-01

    An ionic liquid, 1-butyl-3-methylimidazolium chloride ([C4 mim]Cl)/salt aqueous two-phase systems (ATPS) was presented as a simple, rapid and effective sample pretreatment technique coupled with high-performance liquid chromatography (HPLC) for analysis of the major opium alkaloids in Pericarpium papaveris. To find optimal conditions, the partition behaviors of codeine and papaverine in ionic liquid/salt aqueous two-phase systems were investigated. Various factors were considered systematically, and the results indicated that both the pH value and the salting-out ability of salt had great influence on phase separation. The recoveries of codeine and papaverine were 90.0-100.2% and 99.3-102.0%, respectively, from aqueous samples of P. papaveris by the proposed method. PMID:16143571

  17. Comprehensive Microstructure and Molar Mass Analysis of Polybutadiene by Multidimensional Liquid Chromatography.

    PubMed

    Maiko, Khumo; Pasch, Harald

    2015-12-01

    For the first time, polybutadiene is separated according to microstructure using solvent gradient interaction chromatography (SGIC). Superior separation of polybutadienes having different microstructures is obtained on a silica-based reversed stationary phase and a mobile phase of acetone-hexane. This SGIC system enables the baseline separation of 1,2-polybutadienes and 1,4-polybutadienes even in cases where the samples have similar molar masses. 2D liquid chromatography is performed with the SGIC method separating according to microstructure in the first dimension coupled to size exclusion chromatography separating according to molar mass in the second dimension, thus providing comprehensive information on both microstructure and molar mass.

  18. Comprehensive Microstructure and Molar Mass Analysis of Polybutadiene by Multidimensional Liquid Chromatography.

    PubMed

    Maiko, Khumo; Pasch, Harald

    2015-12-01

    For the first time, polybutadiene is separated according to microstructure using solvent gradient interaction chromatography (SGIC). Superior separation of polybutadienes having different microstructures is obtained on a silica-based reversed stationary phase and a mobile phase of acetone-hexane. This SGIC system enables the baseline separation of 1,2-polybutadienes and 1,4-polybutadienes even in cases where the samples have similar molar masses. 2D liquid chromatography is performed with the SGIC method separating according to microstructure in the first dimension coupled to size exclusion chromatography separating according to molar mass in the second dimension, thus providing comprehensive information on both microstructure and molar mass. PMID:26461063

  19. Toward Sensitive and Accurate Analysis of Antibody Biotherapeutics by Liquid Chromatography Coupled with Mass Spectrometry

    PubMed Central

    An, Bo; Zhang, Ming

    2014-01-01

    Remarkable methodological advances in the past decade have expanded the application of liquid chromatography coupled with mass spectrometry (LC/MS) analysis of biotherapeutics. Currently, LC/MS represents a promising alternative or supplement to the traditional ligand binding assay (LBA) in the pharmacokinetic, pharmacodynamic, and toxicokinetic studies of protein drugs, owing to the rapid and cost-effective method development, high specificity and reproducibility, low sample consumption, the capacity of analyzing multiple targets in one analysis, and the fact that a validated method can be readily adapted across various matrices and species. While promising, technical challenges associated with sensitivity, sample preparation, method development, and quantitative accuracy need to be addressed to enable full utilization of LC/MS. This article introduces the rationale and technical challenges of LC/MS techniques in biotherapeutics analysis and summarizes recently developed strategies to alleviate these challenges. Applications of LC/MS techniques on quantification and characterization of antibody biotherapeutics are also discussed. We speculate that despite the highly attractive features of LC/MS, it will not fully replace traditional assays such as LBA in the foreseeable future; instead, the forthcoming trend is likely the conjunction of biochemical techniques with versatile LC/MS approaches to achieve accurate, sensitive, and unbiased characterization of biotherapeutics in highly complex pharmaceutical/biologic matrices. Such combinations will constitute powerful tools to tackle the challenges posed by the rapidly growing needs for biotherapeutics development. PMID:25185260

  20. On-line comprehensive two-dimensional normal-phase liquid chromatography×reversed-phase liquid chromatography for preparative isolation of toad venom.

    PubMed

    Li, Jia-Fu; Fang, Hua; Yan, Xia; Chang, Fang-Rong; Wu, Zhen; Wu, Yun-Long; Qiu, Ying-Kun

    2016-07-22

    An on-line comprehensive preparative two-dimensional normal-phase liquid chromatography×reversed-phase liquid chromatography (2D NPLC×RPLC) system was constructed with a newly developed vacuum evaporation assisted adsorption (VEAA) interface, allowing fast removal of NPLC solvent in the vacuum condition and successfully solving the solvent incompatibility problem between NPLC and RPLC. The system achieved on-line solvent exchange within the two dimensions and its performance was illustrated by gram-scale isolation of crude extract from the venom of Bufo bufo gargarizans. Within separation time of ∼20h, 19 compounds were obtained with high purity in a single run. With the VEAA interface, the 2D system exhibited apparent advantages in separation efficiency and automation compared with conventional methods, indicating its promising application in the routine separation process for complicated natural products. PMID:27328884

  1. Development of liquid handling techniques in microgravity

    NASA Technical Reports Server (NTRS)

    Antar, Basil N.

    1995-01-01

    A large number of experiments dealing with protein crystal growth and also with growth of crystals from solution require complicated fluid handling procedures including filling of empty containers with liquids, mixing of solutions, and stirring of liquids. Such procedures are accomplished in a straight forward manner when performed under terrestrial conditions in the laboratory. However, in the low gravity environment of space, such as on board the Space Shuttle or an Earth-orbiting space station, these procedures sometimes produced entirely undesirable results. Under terrestrial conditions, liquids usually completely separate from the gas due to the buoyancy effects of Earth's gravity. Consequently, any gas pockets that are entrained into the liquid during a fluid handling procedure will eventually migrate towards the top of the vessel where they can be removed. In a low gravity environment any folded gas bubble will remain within the liquid bulk indefinitely at a location that is not known a priori resulting in a mixture of liquid and vapor.

  2. Separation and purification of sulforaphane from broccoli seeds by solid phase extraction and preparative high-performance liquid chromatography.

    PubMed

    Liang, Hao; Li, Chunfang; Yuan, Qipeng; Vriesekoop, Frank

    2007-10-01

    A novel, rapid, and economical method to isolate and purify natural sulforaphane from broccoli seeds is described. The procedure involves solvent extraction of autolyzed seed meal, followed by separation by solid phase extraction (SPE) and purification by preparative high-performance liquid chromatography (HPLC). The SPE method provides higher yield of sulforaphane from crude extracts compared to conventional liquid-liquid extraction. High purity and recovery of sulforaphane product can be obtained by preparative HPLC with a C 18 column and 30% methanol in water as the mobile phase. The purified compound was characterized by MS and (1)H and (13)C NMR. The techniques described here are useful tools in the preparative-scale isolation of sulforaphane in a fast, cost-effective, and waste-conscious manner.

  3. Technique for detecting liquid metal leaks

    DOEpatents

    Bauerle, James E.

    1979-01-01

    In a system employing flowing liquid metal as a heat transfer medium in contact with tubular members containing a working fluid, i.e., steam, liquid metal leaks through the wall of the tubular member are detected by dislodging the liquid metal compounds forming in the tubular member at the leak locations and subsequently transporting the dislodged compound in the form of an aerosol to a detector responsive to the liquid metal compound. In the application to a sodium cooled tubular member, the detector would consist of a sodium responsive device, such as a sodium ion detector.

  4. Coupling of Molecular Imprinted Polymer Nanoparticles by High Performance Liquid Chromatography as an Efficient Technique for Sensitive and Selective Trace Determination of 4-Chloro-2-Methylphenoxy Acetic Acid in Complex Matrices

    PubMed Central

    OMIDI, Fariborz; BEHBAHANI, Mohammad; SAMADI, Saadi; SEDIGHI, Alireza; SHAHTAHERI, Seyed Jamaleddin

    2014-01-01

    Abstract Background 4-chloro-2-methylphenoxy acetic acid (MCPA) is one of the most important pesticides which is extensively used to control weeds in arable farmland. Exposure to this compound occurs in general population and persons who occupationally handle it. The aim of this present work was the preparation of MCPA imprinting polymer and its application as a selective sample preparation technique for trace determination of MCPA in biological and environmental samples. Methods In this study, MCPA imprinting polymer was obtained by precipitation polymerization using methacrylic acid (the functional monomer), ethylene glycol dimethacrylate (the cross-linker), 2, 2’-azobisisobutyronitrile (the initiator) and MCPA (the template molecule) in acetonitrile solution. The MIP-NPs were characterized by thermogravimetric analysis and scanning electron microscopy. The optimization process was carried out applying batch method. After optimization of the parameters, affecting the adsorption and desorption of analyte, urine and different water samples were used to determine MCPA. Results Imprinted MCPA molecules were removed from the polymeric structure using acetic acid in methanol (20:80 v/v %) as the eluting solvent. Both sorption and desorption process occur within 10 min. The maximum sorbent capacity of the molecular imprinted polymer is 87.4 mg g-1. The relative standard deviation and limit of detection for water samples by introduced selective solid phase extraction were 4.8% and 0.9 μg L-1, and these data for urine samples were 4.5% and 1.60 μg L-1, respectively. Conclusion The developed method was successfully applied to determine MCPA in urine and different water samples. PMID:26060766

  5. Strong cation exchange chiral stationary phase--a comparative study in high-performance liquid chromatography and subcritical fluid chromatography.

    PubMed

    Wolrab, Denise; Macíková, Pavla; Boras, Mario; Kohout, Michal; Lindner, Wolfgang

    2013-11-22

    The performance of a strong cation exchange-type (SCX) chiral stationary phase (CSP) was evaluated with subcritical fluid chromatography (subFC) and high performance liquid chromatography (HPLC). The chromatographic conditions in subFC were optimized by changing the amount of polar organic modifier, concentration of a basic additive in the modifier, system pressure and temperature. In this way the concentration of in situ formed transient ionic species could be varied. The gradual change of the concentration of the transient buffer, i.e. gradient elution conditions in subFC, was found beneficial for separation of a mixture of racemic compounds. The strength and amount of the in situ formed buffer was estimated on the basis of comparative experiments in subSFC and HPLC.

  6. Ultrasound-assisted ionic liquid-based homogeneous liquid-liquid microextraction high-performance liquid chromatography for determination of tanshinones in Salvia miltiorrhiza Bge. root.

    PubMed

    Wang, Zhibing; Cao, Bocheng; Yu, Aimin; Zhang, Hanqi; Qiu, Fangping

    2015-02-01

    The ultrasound-assisted ionic liquid-based homogeneous liquid-liquid microextraction has been developed and applied to the extraction of four tanshinones, including dihydrotanshinone, tanshinone I, cryptotanshinone and tanshinone IIA in Salvia miltiorrhiza Bge. root. High performance liquid chromatography was applied to the separation and determination of the analytes. The ionic liquid was used as extraction solvent and target analytes were extracted with help of ultrasound. Then, ion-pairing agent was added into the sample solution, which resulted in the formation of water-insoluble ionic liquid in the solution. The phase separation was performed by centrifugation. The extraction, concentration and purification of target analytes were performed simultaneously. The experimental parameters, including type and volume of ionic liquid, sample amount, the size of sample particle, pH value of extraction medium, extraction temperature, extraction time, amount of ion-pairing agent and centrifuging time, were investigated and optimized. The calibration curves showed good linear relationship (r>0.9997). The limits of detection and quantification were in the range of 0.052-0.093 and 0.17-0.31 μg mL(-1), respectively. The recoveries were between 70.45% and 94.23% with relative standard deviations lower than 5.31%. The present method is free of volatile organic solvents, and represents lower expenditures of sample, extraction time and solvent, compared with UAE and HRE. There was no obvious difference in the extraction yields of active constitutions obtained by the three extraction methods.

  7. Identification of Unknown Contaminants in Water Samples from ISS Employing Liquid Chromatography/Mass Spectrometry/Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Rutz, Jeffrey A.; Schultz, John R.

    2008-01-01

    Mass Spectrometry/Mass Spectrometry (MS/MS) is a powerful technique for identifying unknown organic compounds. For non-volatile or thermally unstable unknowns dissolved in liquids, liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) is often the variety of MS/MS used for the identification. One type of LC/MS/MS that is rapidly becoming popular is time-of-flight (TOF) mass spectrometry. This technique is now in use at the Johnson Space Center for identification of unknown nonvolatile organics in water samples from the space program. An example of the successful identification of one unknown is reviewed in detail in this paper. The advantages of time-of-flight instrumentation are demonstrated through this example as well as the strategy employed in using time-of-flight data to identify unknowns.

  8. Frozen-Plug Technique for Liquid-Oxygen Plumbing

    NASA Technical Reports Server (NTRS)

    McCaskey, C. E. " Mac" ; Lobmeyer, Dennis; Nagy, Zoltan; Peltzer, Rich

    2005-01-01

    A frozen-plug technique has been conceived as a means of temporarily blocking the flow of liquid oxygen or its vapor through a tube or pipe. The technique makes it possible to perform maintenance, repair, or other work on downstream parts of the cryogenic system in which the oxygen is used, without having to empty an upstream liquid-oxygen reservoir and, hence, without wasting the stored liquid oxygen and without subjecting the reservoir to the stresses of thermal cycling.

  9. DETERMINATION OF CARBENDAZIM IN WATER BY HIGH-PERFORMANCE IMMUNOAFFINITY CHROMATOGRAPHY ON-LINE WITH HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY WITH DIODE-ARRAY OR MASS SPECTROMETRIC DETECTION

    EPA Science Inventory

    An automated method for the determination of carbendazim in water that combines high-performance immunoaffinity chromatography (HPIAC), high-performance liquid chromatography (HPLC) in the reversed-phase mode, and detection by either UV-Vis diode array detector (DAD) spectroscopy...

  10. Application in pesticide analysis: Liquid chromatography - A review of the state of science for biomarker discovery and identification

    EPA Science Inventory

    Book Chapter 18, titled Application in pesticide analysis: Liquid chromatography - A review of the state of science for biomarker discovery and identification, will be published in the book titled High Performance Liquid Chromatography in Pesticide Residue Analysis (Part of the C...

  11. Determination of five antiarrhythmic drugs in human plasma by dispersive liquid-liquid microextraction and high-performance liquid chromatography.

    PubMed

    Jouyban, Abolghasem; Sorouraddin, Mohammad Hossein; Farajzadeh, Mir Ali; Somi, Mohammad Hossein; Fazeli-Bakhtiyari, Rana

    2015-03-01

    A fast and sensitive high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection was developed and validated for the simultaneous quantitation of five antiarrhythmic drugs (metoprolol, propranolol, carvedilol, diltiazem, and verapamil) in human plasma samples. It involves dispersive liquid-liquid microextraction (DLLME) of the desired drugs from 660 µL plasma and separation using isocratic elution with UV detection at 200 nm. The complete separation of all analytes was achieved within 7 min. Acetonitrile (as disperser solvent) resulting from the protein precipitation procedure was mixed with 100 µL dichloromethane (as an extraction solvent) and rapidly injected into 5 mL aqueous solution (pH 11.5) containing 1% (w/v), NaCl. After centrifugation, the sedimented phase containing enriched analytes was collected and evaporated to dryness. The residue was re-dissolved in 50 µL de-ionized water (acidified to pH 3) and injected into the HPLC system for analysis. Under the optimal conditions, the enrichment factors and extraction recoveries ranged between 4.4-10.8 and 33-82%, respectively. The suggested method was linear (r(2) ≥0.997) over a dynamic range of 0.02-0.80 µg mL(-1) in plasma. The intra- and inter-days relative standard deviation (RSD%) and relative error (RE%) values of the method were below 20%, which shows good precision and accuracy. Finally, this method was applied to the analysis of real plasma samples obtained from the patients treated with these drugs.

  12. Analysis of drugs of abuse in human plasma by dispersive liquid-liquid microextraction and high-performance liquid chromatography.

    PubMed

    Fernández, P; Regenjo, M; Bermejo, A M; Fernández, A M; Lorenzo, R A; Carro, A M

    2015-04-01

    Opioids and cocaine are widely used at present, both for recreational purposes and as drugs of abuse. This raises the need to develop new analytical methods specifically designed for the simultaneous detection of several drugs of abuse in biological samples. In this work, dispersive liquid-liquid microextraction (DLLME) was assessed as a new sample treatment for the simultaneous extraction of morphine (MOR), 6-acetylmorphine (6AM), cocaine (COC), benzoylecgonine (BZE) and methadone (MET) from human plasma. Preliminary assays were done before developing an experimental design based on a Uniform Network Doehlert which allowed the optimum extraction conditions to be identified, namely: a volume of extractant solvent (chloroform) and dispersant solvent (acetonitrile) of 220 µl and 3.2 ml, respectively; 0.2 g of NaCl as a salting-out additive; pH 10.6 and ultrasound stirring for 3.5 min. The resulting extracts were analyzed by high-performance liquid chromatography with photodiode array detection (HPLC-PDA), using an XBridge® RP18 column (250 × 4.6 mm i.d., 5 µm particle size). Calibration graphs were linear over the concentration range 0.1-10 µg ml⁻¹, and detection limits ranged from 13.9 to 28.5 ng ml⁻¹. Precision calculated at three different concentration levels in plasma was included in the range 0.1-6.8% RSD. Recoveries of the five drugs were all higher than 84% on average. Finally the proposed method was successfully applied to 22 plasma samples from heroin, cocaine and/or methadone users, and the most frequently detected drug was benzoylecgonine, followed by methadone, cocaine and morphine.

  13. Quantitative determination of penicillin V and amoxicillin in feed samples by pressurised liquid extraction and liquid chromatography with ultraviolet detection.

    PubMed

    Benito-Peña, E; Urraca, J L; Moreno-Bondi, M C

    2009-02-20

    A rapid and simple method is proposed for the routine determination of amoxicillin (AMOX) and penicillin V (PENV) in swine feedingstuffs. The method is based on pressurised liquid extraction (PLE) followed by high performance liquid chromatography with ultraviolet detection (PLE-HPLC-UV) for antibiotic analysis. Parameters affecting PLE procedure, such as temperature, solvent composition, number of extraction cycles and sample cell size, were evaluated in order to achieve the highest extraction efficiency. The optimised method employed 11mL extraction cells, acetonitrile-water mixtures (25:75, v/v) for AMOX and (50:50, v/v) for PENV, as extraction solvent, 102.07atm of extraction pressure, 50 degrees C of extraction temperature, 5min of static time and 60% flush volume of the cell size. Extracts were filtered and directly analysed by HPLC-DAD/UV without further clean-up. Mean recovery rates for feed samples fortified with 200-500mgkg(-1) of both antibiotics were 86% for AMOX (RSD< or =6%) and 95% for PENV (RSD< or =3%). The method was successfully applied to the analysis of a commercial medicated swine feedingstuff, and the results were in good agreement with those obtained using mechanical shaking or ultrasonic extraction combined with solid phase extraction (UE-SPE), previously applied in the literature for feed analysis. The extraction efficiencies were evaluated by statistical comparison (analysis of variance, ANOVA-single factor) of the results obtained using the different extraction methods. Compared to the alternative techniques, PLE offers several practical advantages: easy to perform, fast, savings in solvent volume and in time, all steps are fully automated and further clean-up is not necessary for penicillin analysis.

  14. Sources of Variability in Chlorophyll Analysis by Fluorometry and by High Performance Liquid Chromatography. Chapter 22

    NASA Technical Reports Server (NTRS)

    VanHeukelem, Laurie; Thomas, Crystal S.; Glibert, Patricia M.

    2001-01-01

    The need for accurate determination of chlorophyll a (chl a) is of interest for numerous reasons. From the need for ground-truth data for remote sensing to pigment detection for laboratory experimentation, it is essential to know the accuracy of the analyses and the factors potentially contributing to variability and error. Numerous methods and instrument techniques are currently employed in the analyses of chl a. These methods range from spectrophotometric quantification, to fluorometric analysis and determination by high performance liquid chromatography. Even within the application of HPLC techniques, methods vary. Here we provide the results of a comparison among methods and provide some guidance for improving the accuracy of these analyses. These results are based on a round-robin conducted among numerous investigators, including several in the Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) and HyCODE Programs. Our purpose here is not to present the full results of the laboratory intercalibration; those results will be presented elsewhere. Rather, here we highlight some of the major factors that may contribute to the variability observed. Specifically, we aim to assess the comparability of chl a analyses performed by fluorometry and HPLC, and we identify several factors in the analyses which may contribute disproportionately to this variability.

  15. Analysis of plant nucleotide sugars by hydrophilic interaction liquid chromatography and tandem mass spectrometry.

    PubMed

    Ito, Jun; Herter, Thomas; Baidoo, Edward E K; Lao, Jeemeng; Vega-Sánchez, Miguel E; Michelle Smith-Moritz, A; Adams, Paul D; Keasling, Jay D; Usadel, Björn; Petzold, Christopher J; Heazlewood, Joshua L

    2014-03-01

    Understanding the intricate metabolic processes involved in plant cell wall biosynthesis is limited by difficulties in performing sensitive quantification of many involved compounds. Hydrophilic interaction liquid chromatography is a useful technique for the analysis of hydrophilic metabolites from complex biological extracts and forms the basis of this method to quantify plant cell wall precursors. A zwitterionic silica-based stationary phase has been used to separate hydrophilic nucleotide sugars involved in cell wall biosynthesis from milligram amounts of leaf tissue. A tandem mass spectrometry operating in selected reaction monitoring mode was used to quantify nucleotide sugars. This method was highly repeatable and quantified 12 nucleotide sugars at low femtomole quantities, with linear responses up to four orders of magnitude to several 100pmol. The method was also successfully applied to the analysis of purified leaf extracts from two model plant species with variations in their cell wall sugar compositions and indicated significant differences in the levels of 6 out of 12 nucleotide sugars. The plant nucleotide sugar extraction procedure was demonstrated to have good recovery rates with minimal matrix effects. The approach results in a significant improvement in sensitivity when applied to plant samples over currently employed techniques.

  16. Straightforward single-calibrant quantification of seized designer drugs by liquid chromatography-chemiluminescence nitrogen detection.

    PubMed

    Rasanen, Ilpo; Kyber, Marianne; Szilvay, Ilmari; Rintatalo, Janne; Ojanperä, Ilkka

    2014-04-01

    Sixty-one different psychoactive substances were quantified by liquid chromatography-chemiluminescence nitrogen detection (LC-CLND) in 177 samples, using a single secondary standard (caffeine), in a trial concerning the quantitative purity assessment of drug-related material seized by the police in 2011-2012 and customs in 2011-2013 in Finland. The substances found were predominantly substituted phenethylamines, cathinones, tryptamines and synthetic cannabinoids, which were identified by appropriate methods prior to submitting the samples for quantification by LC-CLND. The equimolarity and expanded uncertainty of measurement by LC-CLND were on average 95% and 13%, respectively, based on 16 different substances. The median (mean) purity of stimulant/hallucinogenic drug samples seized at the border was 92.9% (87.6%) and in the street 82.0% (64.5%). The corresponding figures for powdery synthetic cannabinoid samples seized at the border and in the street were 99.0% (96.8%) and 90.0% (92.2%), respectively. There was generally only one active drug to be quantified in each sample. Seized herbal samples contained 0.15-9.2% of between one and three components. LC-CLND was found to be suitable for quantification of the nitrogen-containing drugs encountered in the study, showing sufficient N-equimolarity for both stimulant/hallucinogenic drugs and synthetic cannabinoids. The technique possesses great potential as a standard technique in forensic laboratories.

  17. Methods for analysis of conjugated linoleic acids and trans-18:1 isomers in dairy fats by using a combination of gas chromatography, silver-ion thin-layer chromatography/gas chromatography, and silver-ion liquid chromatography.

    PubMed

    Cruz-Hernandez, Cristina; Deng, Zeyuan; Zhou, Jianqiang; Hill, Arthur R; Yurawecz, Martin P; Delmonte, Pierluigi; Mossoba, Magdi M; Dugan, Michael E R; Kramer, John K G

    2004-01-01

    Conjugated linoleic acids (CLA) are octadecadienoic acids (18:2) that have a conjugated double-bond system. Interest in these compounds has expanded since CLA were found to be associated with a number of physiological and pathological responses such as cancer, metastases, atherosclerosis, diabetes, immunity, and body fat/protein composition. The main sources of these conjugated fatty acids are dairy fats. Rumen bacteria convert polyunsaturated fatty acids, especially linoleic and linolenic acids, to CLA and numerous trans- containing mono- and diunsaturated fatty acids. It has been established that an additional route of CLA synthesis in ruminants and monogastric animals, including humans, occurs via delta9 desaturation of the trans-18:1 isomers. To date, a total of 6 positional CLA isomers have been found in dairy fats, each occurring in 4 geometric forms (cis,trans; trans,cis; cis,cis; and trans,trans) for a total of 24. All of these CLA isomers can be resolved only by a combination of gas chromatography (GC), using 100 m highly polar capillary columns, and silver-ion liquid chromatography, using 3 of these 25 cm columns in series. Complete analysis of all the trans-18:1 isomers requires prior isolation of trans monoenes by silver-ion thin-layer chromatography (TLC), followed by GC analysis using the same 100 m capillary columns operated at low temperatures starting from 120 degrees C. These analytical techniques are required to assess the purity of commercial CLA preparations, because their purity will affect the interpretation of any physiological and/or biochemical response obtained. Prior assessment of CLA preparations by TLC is also recommended to determine the presence of any other impurities. The availability of pure CLA isomers will permit the evaluation and analysis of individual CLA isomers for their nutritional and biological activity in model systems, animals, and humans. These techniques are also essential to evaluate dairy fats for their content of

  18. 3D printed metal columns for capillary liquid chromatography.

    PubMed

    Sandron, S; Heery, B; Gupta, V; Collins, D A; Nesterenko, E P; Nesterenko, P N; Talebi, M; Beirne, S; Thompson, F; Wallace, G G; Brabazon, D; Regan, F; Paull, B

    2014-12-21

    Coiled planar capillary chromatography columns (0.9 mm I.D. × 60 cm L) were 3D printed in stainless steel (316L), and titanium (Ti-6Al-4V) alloys (external dimensions of ~5 × 30 × 58 mm), and either slurry packed with various sized reversed-phase octadecylsilica particles, or filled with an in situ prepared methacrylate based monolith. Coiled printed columns were coupled directly with 30 × 30 mm Peltier thermoelectric direct contact heater/cooler modules. Preliminary results show the potential of using such 3D printed columns in future portable chromatographic devices. PMID:25285334

  19. Gold nanoparticle decorated graphene oxide/silica composite stationary phase for high-performance liquid chromatography.

    PubMed

    Liang, Xiaojing; Wang, Xusheng; Ren, Haixia; Jiang, Shengxiang; Wang, Licheng; Liu, Shujuan

    2014-06-01

    In the initial phase of this study, graphene oxide (GO)/silica was fabricated by assembling GO onto the silica particles, and then gold nanoparticles (GNPs) were used to modify the GO/silica to prepare a novel stationary phase for high-performance liquid chromatography. The new stationary phase could be used in both reversed-phase chromatography and hydrophilic interaction liquid chromatography modes. Good separations of alkylbenzenes, isomerides, amino acids, nucleosides, and nucleobases were achieved in both modes. Compared with the GO/silica phase and GNPs/silica phase, it is found that except for hydrophilicity, large π-electron systems, hydrophobicity, and coordination functions, this new stationary phase also exhibited special separation performance due to the combination of 2D GO with zero-dimensional GNPs. PMID:24723561

  20. Gold nanoparticle decorated graphene oxide/silica composite stationary phase for high-performance liquid chromatography.

    PubMed

    Liang, Xiaojing; Wang, Xusheng; Ren, Haixia; Jiang, Shengxiang; Wang, Licheng; Liu, Shujuan

    2014-06-01

    In the initial phase of this study, graphene oxide (GO)/silica was fabricated by assembling GO onto the silica particles, and then gold nanoparticles (GNPs) were used to modify the GO/silica to prepare a novel stationary phase for high-performance liquid chromatography. The new stationary phase could be used in both reversed-phase chromatography and hydrophilic interaction liquid chromatography modes. Good separations of alkylbenzenes, isomerides, amino acids, nucleosides, and nucleobases were achieved in both modes. Compared with the GO/silica phase and GNPs/silica phase, it is found that except for hydrophilicity, large π-electron systems, hydrophobicity, and coordination functions, this new stationary phase also exhibited special separation performance due to the combination of 2D GO with zero-dimensional GNPs.

  1. [Determination of five triazine herbicides in infant milk powder by high performance liquid chromatography coupled with ionic liquid-based homogeneous liquid-liquid microextraction].

    PubMed

    Zhang, Liyuan; Yao, Di; Li, Na; Zhang, Hanqi; Yu, Aimin

    2015-07-01

    A high performance liquid chromatography coupled with homogeneous liquid-liquid microextraction was developed for the determination of five triazine herbicides in infant milk powders. The ionic liquid was used as microextraction solvent. The separation of the herbicides was performed on an Eclipse XDB-C18 column using acetonitrile and water as mobile phases in gradient mode. The effects of homogeneous liquid-liquid extraction conditions on the experimental results were investigated in detail. Under the optimized experimental conditions, the calibration curves for determining the analytes were linear and the correlation coefficients were ≥ 0.9992. The limits of detection for cyanazine, desmetryn, terbumeton, terbuthylazine and dimethametryn were 12.1, 13.8, 11.8, 14.6 and 13.7 μg/kg, respectively. The recoveries of the analytes spiked in four infant milk powders ranged from 92.2% to 103.2% and the relative standard deviations were lower than 6%. This method is sensitive, simple, and suitable for the determination of triazine herbicides in milk powder samples. PMID:26672205

  2. [Determination of five triazine herbicides in infant milk powder by high performance liquid chromatography coupled with ionic liquid-based homogeneous liquid-liquid microextraction].

    PubMed

    Zhang, Liyuan; Yao, Di; Li, Na; Zhang, Hanqi; Yu, Aimin

    2015-07-01

    A high performance liquid chromatography coupled with homogeneous liquid-liquid microextraction was developed for the determination of five triazine herbicides in infant milk powders. The ionic liquid was used as microextraction solvent. The separation of the herbicides was performed on an Eclipse XDB-C18 column using acetonitrile and water as mobile phases in gradient mode. The effects of homogeneous liquid-liquid extraction conditions on the experimental results were investigated in detail. Under the optimized experimental conditions, the calibration curves for determining the analytes were linear and the correlation coefficients were ≥ 0.9992. The limits of detection for cyanazine, desmetryn, terbumeton, terbuthylazine and dimethametryn were 12.1, 13.8, 11.8, 14.6 and 13.7 μg/kg, respectively. The recoveries of the analytes spiked in four infant milk powders ranged from 92.2% to 103.2% and the relative standard deviations were lower than 6%. This method is sensitive, simple, and suitable for the determination of triazine herbicides in milk powder samples.

  3. Microwave-assisted ionic liquid homogeneous liquid-liquid microextraction coupled with high performance liquid chromatography for the determination of anthraquinones in Rheum palmatum L.

    PubMed

    Wang, Zhibing; Hu, Jianxue; Du, Hongxia; He, Shuang; Li, Qing; Zhang, Hanqi

    2016-06-01

    The microwave-assisted ionic liquid homogeneous liquid-liquid microextraction (MA-IL-HLLME) coupled with high performance liquid chromatography with diode array detection (HPLC-DAD) was developed for the determination of anthraquinones, including aloe-emodin, emodin, chrysophanol and physcion in root of Rheum palmatum L. Several experimental parameters influencing the extraction efficiency, including amount of sample, type and volume of ionic liquid, volume and pH value of extraction medium, microwave power and extraction time, concentration of NH4PF6 as well as centrifugal condition were optimized. When 140μL of ionic liquid ([C8MIM][BF4]) was used as an extraction solvent, target analytes can be extracted from sample matrix in one minute with the help of microwave irradiation. The MA-IL-HLLME is simple and quick. The calibration curves exhibited good linear relationship (r>0.9984). The limits of detection and quantification were in the range of 0.015-0.026 and 0.051-0.088μgmL(-1), respectively. The spiked recovery for each analyte was in the range of 81.13-93.07% with relative standard deviations lower than 6.89%. The present method is free of volatile organic solvents, and represents lower expenditures of sample, extraction time and solvent, compared with ultrasonic and heat reflux extraction. The results indicated that the present method can be successfully applied to the determination of anthraquinones in medicinal plant.

  4. Determination of low molecular weight thiols using monobromobimane fluorescent labeling and high-performance liquid chromatography

    NASA Technical Reports Server (NTRS)

    Fahey, Robert C.; Newton, Gerald L.

    1988-01-01

    Methods are described for the preparation and high-performance liquid chromatography (HPLC) analysis of monobromobimane derivatives of low molecular weight thiols in extracts of biological samples. Typical problems encountered in the development and application of these methods are discussed. Analysis of mung bean extract is used as an example.

  5. An Advanced, Interactive, High-Performance Liquid Chromatography Simulator and Instructor Resources

    ERIC Educational Resources Information Center

    Boswell, Paul G.; Stoll, Dwight R.; Carr, Peter W.; Nagel, Megan L.; Vitha, Mark F.; Mabbott, Gary A.

    2013-01-01

    High-performance liquid chromatography (HPLC) simulation software has long been recognized as an effective educational tool, yet many of the existing HPLC simulators are either too expensive, outdated, or lack many important features necessary to make them widely useful for educational purposes. Here, a free, open-source HPLC simulator is…

  6. Benzoin Condensation: Monitoring a Chemical Reaction by High-Pressure Liquid Chromatography

    ERIC Educational Resources Information Center

    Bhattacharya, Apurba; Purohit, Vikram C.; Bellar, Nicholas R.

    2004-01-01

    High-pressure liquid chromatography (HPLC) is the preferred method of separating a variety of materials in complex mixtures such as pharmaceuticals, polymers, soils, food products and biological fluids and is also considered to be a powerful analytical tool in both academia and industry. The use of HPLC analysis as a means of monitoring and…

  7. Analysis of Currently Available Analgesic Tablets by Modern Liquid Chromatography: An Undergraduate Laboratory Introduction to HPLC.

    ERIC Educational Resources Information Center

    Kagel, R. A.; Farwell, S. O.

    1983-01-01

    Background information, procedures, and results, are provided for an undergraduate experiment in which analgesic tablets are analyzed using liquid chromatography. The experiment, an improved, modified version of the Waters Associates Inc. experiment, is simple to prepare, requiring little glassware and minimal sample manipulation by students. (JN)

  8. Extraction and Purification of Glucoraphanin by Preparative High-Performance Liquid Chromatography (HPLC)

    ERIC Educational Resources Information Center

    Lee, Iris; Boyce, Mary C.

    2011-01-01

    A student activity that focuses on the isolation of glucoraphanin from broccoli using preparative high-performance liquid chromatography (HPLC) is presented here. Glucoraphanin is a glucosinolate, whose byproducts are known to possess anticancer properties. It is present naturally at high levels in broccoli and other "Brassica" vegetables. This…

  9. The Separation and Identification of Straight Chain Hydrocarbons: An Experiment Using Gas-Liquid Chromatography.

    ERIC Educational Resources Information Center

    Benson, G. A.

    1982-01-01

    An experiment using gas-liquid chromatography is discussed, introducing the student to concept of dead volume and its measurement, idea and use of an internal reference compound, and to linear relationship existing between measurements of a separation on two different stationary phases. (Author/SK)

  10. (PRESENT AT NCCU) ANALYSIS OF SELECTED PYRETHROID PESTICIDES USING REVERSE PHASE HIGH LIQUID CHROMATOGRAPHY

    EPA Science Inventory

    This research was conducted in cooperation with EPA Region 4 in Athens, GA to develop a method to analyze selected pyrethroid pesticides using Reverse Phase-High Pressure Liquid Chromatography (HPLC). This HPLC method will aid researchers in separating and identifying these pyre...

  11. ANALYSIS OF SELECTED PYRETHROID PESTICIDES USING REVERSE PHASE HIGH PRESSURE LIQUID CHROMATOGRAPHY/UV

    EPA Science Inventory

    This research was conducted in cooperation with EPA Region 4 in Athens, GA to develop a method to analyze selected pyrethroid pesticides using Reverse Phase-High Pressure Liquid Chromatography (HPLC). This HPLC method will aid researchers in separating and identifying these py...

  12. Sensitive, Preclinical Detection of Prions in Brain by nanospray liquid chromatography/tandem mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    More sensitive detection of prions in brain is important because it would allow early detection of disease in young animals and assure a safer food supply. We quantitated the amount of proteinase K-resistant prion protein (PrP 27-30) by use of nano-scale liquid chromatography coupled to a tandem ma...

  13. High-Performance Liquid Chromatography in the Undergraduate Chemical Engineering Laboratory

    ERIC Educational Resources Information Center

    Frey, Douglas D.; Guo, Hui; Karnik, Nikhila

    2013-01-01

    This article describes the assembly of a simple, low-cost, high-performance liquid chromatography (HPLC) system and its use in the undergraduate chemical engineering laboratory course to perform simple experiments. By interpreting the results from these experiments students are able to gain significant experience in the general method of…

  14. High pressure liquid chromatography of cannabinoids as their fluorescent dansyl derivatives.

    PubMed

    Abbott, S R; Abu-Shumays, A

    1975-01-01

    Four different cannabinoids were converted to their 1-dimethyl-aminonaphthalene-5-sulfonate (dansyl) derivatives. Standards mixtures were separated by high pressure liquid chromatography and detected with an experimental filter fluorometer with sub-nanogram sensitivity. The effect of solvent properties on fluorescence spectra and quantum yields was also studied.

  15. DETERMINATION OF CHLOROPHENOLS, NITROPHENOLS, AND METHYLPHENOLS IN GROUND-WATER SAMPLES USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

    EPA Science Inventory

    A high performance liquid chromatography (HPLC) method was developed to quantitatively determine phenolic compounds and their isomers in aqueous samples. The HPLC method can analyze a mixture of 15 contaminants in the same analytical run with an analysis time of 25 minutes. The...

  16. DETERMINATION OF CHLOROPHEONIS, NITROPHENOIS AND METHYLPHENOIS IN GROUND-WATER SAMPLES USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

    EPA Science Inventory

    A high performance liquid chromatography (HPLC) method was developed to quantitatively determine phenolic compounds and their isomers in aqueous samples. The HPLC method can analyze a mixture of 15 contaminants in the same analytical run with an analysis time of 25 minutes. The...

  17. MEASUREMENT OF OXIDATIVE STRESS PARAMETERS USING LIQUID CHROMATOGRAPHY - TANDEM MASS SPECTROSCOPY (LC-MS/MS)

    EPA Science Inventory

    What is the study?
    An invited review article. Measurement of oxidative stress parameters using liquid chromatography-tandem mass spectroscopy (LC-MS/MS)
    Why was it done?
    Although oxidative stress is frequently cited as a cause of various adverse biological eff...

  18. Sugar Determination in Foods with a Radially Compressed High Performance Liquid Chromatography Column.

    ERIC Educational Resources Information Center

    Ondrus, Martin G.; And Others

    1983-01-01

    Advocates use of Waters Associates Radial Compression Separation System for high performance liquid chromatography. Discusses instrumentation and reagents, outlining procedure for analyzing various foods and discussing typical student data. Points out potential problems due to impurities and pump seal life. Suggests use of ribose as internal…

  19. Going Beyond, Going Further: An Inexpensive Experiment for the Introduction of High Performance Liquid Chromatography.

    ERIC Educational Resources Information Center

    Bidlingmeyer, Brian A.; Warren, F. Vincent, Jr.

    1984-01-01

    Background information, materials needed, laboratory procedures, and typical results are provided for five high performance liquid chromatography experiments (three isocratic and two step gradient separations). Suggestions for further experimentation are also provided, including quantitative determinations and separation of charged solutes. (JN)

  20. Quantitative separation of tetralin hydroperoxide from its decomposition products by high performance liquid chromatography

    NASA Technical Reports Server (NTRS)

    Worstell, J. H.; Daniel, S. R.

    1981-01-01

    A method for the separation and analysis of tetralin hydroperoxide and its decomposition products by high pressure liquid chromatography has been developed. Elution with a single, mixed solvent from a micron-Porasil column was employed. Constant response factors (internal standard method) over large concentration ranges and reproducible retention parameters are reported.

  1. Determination of trace anions in liquefied petroleum gas using liquid absorption and electrokinetic migration for enrichment followed by ion chromatography.

    PubMed

    Li, Meilan; Yang, Jianmin; Li, Hai-Fang; Lin, Jin-Ming

    2012-06-01

    A simple sample enrichment technique, electrokinetic migration enrichment in single phase using a designed device, coupled with ion chromatography is presented for the determination of four anions (H(2)PO(4)(-), Cl(-), NO(3)(-), and SO(4)(2-)) in liquefied petroleum gas by liquid adsorption. The electrokinetic migration enrichment is based on the phenomenon of ion electrokinetic migration to the opposite electrode. When the anions migrated to the anode in a smaller volume chamber under the electric field, the concentration was realized. The main parameters affecting enrichment efficiency of applied voltage and enrichment time were investigated. The ion chromatography condition for anions separation was also studied. Under the optimal electrokinetic migration enrichment and ion chromatography conditions, the four anions were detected simultaneously with good linear relationship (r(2) = 0.9908-0.9968) and high precisions (less than 5% of the relative standard deviations of peak areas). The limits of detection of anions (S/N of 3) were in the range of 8-600 μg L(-1). The enrichment factors of the four anions ranged from 3.1 to 5.8. The established method was successfully applied to the analysis of the trace anions in liquefied petroleum gas by liquid adsorption with satisfactory results. The advantages of this method are simple operation and low cost.

  2. Suitability of a liquid chromatography assay of neomycin sulfate to replace the microbiological assay for neomycin in USP Monographs.

    PubMed

    Hanko, Valoran P; Rohrer, Jeffrey S

    2010-01-01

    The current USP National Formulary contains 65 Monographs for drug formulations containing neomycin. All 65 Monographs prescribe a bioassay for neomycin assay. This bioassay, based on cell culture, is labor intensive, has poor precision, and cannot be adapted for purity or identification. High-performance anion-exchange chromatography with integrated pulsed amperometric detection (HPAE-IPAD), a liquid chromatography technique, has been shown to be suitable for neomycin purity analysis and neomycin assay of an over-the-counter first aid cream (Hanko and Rohrer [17]). Here we propose that an HPAE-IPAD assay can replace the bioassay in the 65 neomycin-containing Monographs. We applied the HPAE-IPAD assay to four neomycin-containing drug products representing the four classes of formulations found in the 65 Monographs, liquid, solid, suspension, and cream. Each drug was analyzed with two chromatography systems, and on 3 separate days. For all products, HPAE-IPAD measurements were precise and accurate with respect to the label concentrations. There was also high accuracy for spike recovery of neomycin from the four drug products throughout 70-150% of the labeled concentration. These results suggest that an HPAE-IPAD assay would be an accurate assay for neomycin, and would be faster and more precise than the current bioassay.

  3. Detection of Geothermal Phosphite Using High Performance Liquid Chromatography

    PubMed Central

    Pech, Herbe; Henry, Amanda; Khachikian, Crist S.; Salmassi, Tina M.; Hanrahan, Grady; Foster, Krishna L.

    2009-01-01

    Little is known about the pre-biotic mechanisms that initiated the bioavailability of phosphorus, an element essential to life. A better understanding of phosphorus speciation in modern earth environments representative of early earth, may help to elucidate the origins of bioavailable phosphorus. This paper presents the first quantitative measurements of phosphite in a pristine geothermal pool representative of early earth. Phosphite and phosphate were initially identified and quantified in geothermal pool and stream samples at Hot Creek Gorge near Mammoth Lakes, California using suppressed conductivity ion chromatography. Results confirmed the presence of 0.06 ± 0.02 μM of phosphite and 0.05 ± 0.01 μM of phosphate in a geothermal pool. In the stream, phosphite concentrations were below detection limit (0.04 μM) and phosphate was measured at 1.06 ± 0.36 μM. The presence of phosphite in the geothermal pool was confirmed using both chemical oxidation and ion chromatography/mass spectrometry. PMID:19921877

  4. Detection of geothermal phosphite using high-performance liquid chromatography.

    PubMed

    Pech, Herbe; Henry, Amanda; Khachikian, Crist S; Salmassi, Tina M; Hanrahan, Grady; Foster, Krishna L

    2009-10-15

    Little is known about the prebiotic mechanisms that initiated the bioavailability of phosphorus, an element essential to life. A better understanding of phosphorus speciation in modern earth environments representative of early earth may help to elucidate the origins of bioavailable phosphorus. This paper presents the first quantitative measurements of phosphite in a pristine geothermal pool representative of early earth. Phosphite and phosphate were initially identified and quantified in geothermal pool and stream samples at Hot Creek Gorge near Mammoth Lakes, California, using suppressed conductivity ion chromatography. Results confirmed the presence of 0.06 +/- 0.02 microM of phosphite and 0.05 +/- 0.01 microM of phosphate in a geothermal pool. In the stream, phosphite concentrations were below detection limit (0.04 microM) and phosphate was measured at 1.06 +/- 0.36 microM. The presence of phosphite in the geothermal pool was confirmed using both chemical oxidation and ion chromatography/mass spectrometry.

  5. Determination of trans-10-hydroxy-2-decenoic acid content in pure royal jelly and royal jelly products by column liquid chromatography.

    PubMed

    Genç, M; Aslan, A

    1999-04-16

    In this research, several royal jellies and commercial products containing royal jelly were analysed for their trans-10-hydroxy-2-decenoic acid (10-HDA) content by using a column liquid chromatography technique. Ten samples claimed to be pure royal jelly, containing 10-HDA between 0.75 and 2.54%. Seven samples claimed to contain royal jelly as an ingredient which ranged from non-detectable to 0.054%. The technique was found to be rapid with high recovery.

  6. Position sensitive radioactivity detection for gas and liquid chromatography

    DOEpatents

    Cochran, Joseph L.; McCarthy, John F.; Palumbo, Anthony V.; Phelps, Tommy J.

    2001-01-01

    A method and apparatus are provided for the position sensitive detection of radioactivity in a fluid stream, particularly in the effluent fluid stream from a gas or liquid chromatographic instrument. The invention represents a significant advance in efficiency and cost reduction compared with current efforts.

  7. Liquid chromatography – high resolution mass spectrometry analysis of fatty acid metabolism

    PubMed Central

    Kamphorst, Jurre J.; Fan, Jing; Lu, Wenyun; White, Eileen; Rabinowitz, Joshua D.

    2011-01-01

    We present a liquid chromatography – mass spectrometry (LC-MS) method for long-chain and very-long-chain fatty acid analysis, and its application to 13C-tracer studies of fatty acid metabolism. Fatty acids containing 14 to 36 carbon atoms are separated by C8 reversed-phase chromatography using a water-methanol gradient with tributylamine as ion pairing agent, ionized by electrospray, and analyzed by a stand-alone orbitrap mass spectrometer. The median limit of detection is 5 ng/ml with a linear dynamic range of 100-fold. Ratios of unlabeled to 13C-labeled species are quantitated precisely and accurately (average relative standard deviation 3.2% and deviation from expectation 2.3%). In samples consisting of fatty acids saponified from cultured mammalian cells, 45 species are quantified, with average intraday relative standard deviations for independent biological replicates of 11%. The method enables quantitation of molecular ion peaks for all labeled forms of each fatty acid. Different degrees of 13C-labeling from glucose and glutamine correspond to fatty acid uptake from media, de novo synthesis, and elongation. To exemplify the utility of the method, we examined isogenic cell lines with and without activated Ras oncogene expression. Ras increases the abundance and alters the labeling patterns of saturated and monounsaturated very-long-chain fatty acids, with the observed pattern consistent with Ras leading to enhanced activity of ELOVL4 or an enzyme with similar catalytic activity. This LC-MS method and associated isotope tracer techniques should be broadly applicable to investigating fatty acid metabolism. PMID:22004349

  8. An improved method for measuring metaldehyde in surface water using liquid chromatography tandem mass spectrometry

    PubMed Central

    Schumacher, Melanie; Castle, Glenn; Gravell, Anthony; Mills, Graham A.; Fones, Gary R.

    2016-01-01

    The molluscicide metaldehyde (2,4,6,8-tetramethyl-1,3,5,7-tetraoxocanemetacetaldehyde) is an emerging pollutant. It is frequently detected in surface waters, often above the European Community Drinking Water Directive limit of 0.1 μg/L for a single pesticide. Gas chromatography mass spectrometry (GC–MS) can be used to determine metaldehyde in environmental waters, but this method requires time consuming extraction techniques prior to instrumental analysis. Use of liquid chromatography-tandem mass spectrometry (LC–MS/MS) can overcome this problem. We describe a novel LC–MS/MS method, using a methylamine mobile phase additive, coupled with on-line sample enrichment that allows for the rapid and sensitive measurement of metaldehyde in surface water. Only the methylamine adduct of metaldehyde was formed with other unwanted alkali metal adducts and dimers being suppressed. As considerably less collision energy is required to fragment the methylamine adduct, a five-fold improvement in method sensitivity, compared to a previous method using an ammonium acetate buffer mobile phase was achieved. This new approach offers: • A validated method that meets regulatory requirements for the determination of metaldehyde in surface water. • Improved reliability of quantification over existing LC–MS/MS methods by using stable precursor ions for multiple reaction monitoring. • Low limits of quantification for tap water (4 ng/L) and river water (20 ng/L) using only 800 μL of sample; recoveries > 97%. PMID:27054094

  9. High Performance Thin Layer Chromatography.

    ERIC Educational Resources Information Center

    Costanzo, Samuel J.

    1984-01-01

    Clarifies where in the scheme of modern chromatography high performance thin layer chromatography (TLC) fits and why in some situations it is a viable alternative to gas and high performance liquid chromatography. New TLC plates, sample applications, plate development, and instrumental techniques are considered. (JN)

  10. Determination of synthetic hormones in animal urine by high-performance liquid chromatography/mass spectrometry.

    PubMed

    Rúbies, Antoni; Cabrera, Albert; Centrich, Francesc

    2007-01-01

    A method was developed for the extraction of stanozolol, taleranol, zeranol, hexestrol, dienestrol, ethynylestradiol, diethylstilbestrol, and trenbolone from animal urine. The analytes were extracted from the matrix by enzymatic hydrolysis, solid-phase extraction, and liquid-liquid extraction. Detection and quantitation were performed on a high-performance liquid chromatography system coupled to a triple quadrupole mass spectrometer. The identification criteria met the European Union regulations. Validation of this method established a decision limit between 0.2 and 0.9 microg/L and a detection capability between 0.3 and 1.0 microg/L, depending on the analyte.

  11. Determination of synthetic hormones in animal urine by high-performance liquid chromatography/mass spectrometry.

    PubMed

    Rúbies, Antoni; Cabrera, Albert; Centrich, Francesc

    2007-01-01

    A method was developed for the extraction of stanozolol, taleranol, zeranol, hexestrol, dienestrol, ethynylestradiol, diethylstilbestrol, and trenbolone from animal urine. The analytes were extracted from the matrix by enzymatic hydrolysis, solid-phase extraction, and liquid-liquid extraction. Detection and quantitation were performed on a high-performance liquid chromatography system coupled to a triple quadrupole mass spectrometer. The identification criteria met the European Union regulations. Validation of this method established a decision limit between 0.2 and 0.9 microg/L and a detection capability between 0.3 and 1.0 microg/L, depending on the analyte. PMID:17474533

  12. Separation of carbohydrates using hydrophilic interaction liquid chromatography.

    PubMed

    Fu, Qing; Liang, Tu; Li, Zhenyu; Xu, Xiaoyong; Ke, Yanxiong; Jin, Yu; Liang, Xinmiao

    2013-09-20

    A strategy was developed to rapidly evaluate chromatographic properties of hydrophilic interaction chromatography (HILIC) columns for separating carbohydrates. Seven HILIC columns (Silica, Diol, TSK Amide-80, XAmide, Click Maltose, Click β-CD, and Click TE-Cys columns) were evaluated by using three monosaccharide and seven disaccharides as probes. The influence of column temperature on the peak shape and tautomerization of carbohydrates, as well as column selectivity were investigated. The influence of surface charge property on the retention was also studied by using glucose, glucuronic acid, and glucosamine, which indicated that buffer salt concentration and pH value in mobile phase was necessary to control the ionic interactions between ionic carbohydrates and HILIC columns. According to evaluation results, the XAmide column was selected as an example to establish experimental schemes for separation of complex mixtures of oligosaccharide.

  13. Combined use of liquid chromatography triple quadrupole mass spectrometry and liquid chromatography quadrupole time-of-flight mass spectrometry in systematic screening of pesticides and other contaminants in water samples.

    PubMed

    Masiá, A; Ibáñez, M; Blasco, C; Sancho, J V; Picó, Y; Hernández, F

    2013-01-25

    As a suitable way for routine screening of pesticides and control of other organic contaminants in water, the combination of liquid chromatography triple quadrupole tandem mass spectrometry (LC-QqQ-MS/MS) and liquid chromatography-hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) has been applied to the analysis of 63 surface and waste water samples after conventional solid-phase extraction (SPE). The extracts were screened for 43 pesticides or degradation products by LC-QqQ-MS/MS achieving limits of detection (LOD) ranged from 0.04 to 2 ng L(-1). Of the 43 selected pesticides, 33 were detected in water samples. The ESI-QTOF MS instrument was run using two simultaneous acquisition functions with low and high collision energy (MS(E) approach) and acquiring the full mass spectra. A home-made database containing more than 1100 organic pollutants was used for substance identification. Around 250 of these compounds were available at the laboratory as reference standards. Five pesticides and 3 of their degradation products, different to those selected in the QqQ method, were detected by QqTOF-MS. Thirteen pharmaceuticals and two drugs of abuse were also identified in the samples. In practice, the sample preparation proved to be suitable for both techniques and for a wide variety of substances with different polarity. Mutual confirmation and evidence of co-occurrence of several other organic contaminants were the main advantages of the combination of both techniques. PMID:23312322

  14. Supported liquid membrane-liquid chromatography-mass spectrometry analysis of cyanobacterial toxins in fresh water systems

    NASA Astrophysics Data System (ADS)

    Mbukwa, Elbert A.; Msagati, Titus A. M.; Mamba, Bhekie B.

    Harmful algal blooms (HABs) are increasingly becoming of great concern to water resources worldwide due to indiscriminate waste disposal habits resulting in water pollution and eutrophication. When cyanobacterial cells lyse (burst) they release toxins called microcystins (MCs) that are well known for their hepatotoxicity (causing liver damage) and have been found in eutrophic lakes, rivers, wastewater ponds and other water reservoirs. Prolonged exposure to low concentrated MCs are equally of health importance as they are known to be bioaccumulative and even at such low concentration do exhibit toxic effects to aquatic animals, wildlife and human liver cells. The application of common treatment processes for drinking water sourced from HABs infested reservoirs have the potential to cause algal cell lyses releasing low to higher amounts of MCs in finished water. Trace microcystins in water/tissue can be analyzed and quantified using Liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) following solid-phase extraction (SPE) sample clean-up procedures. However, extracting MCs from algal samples which are rich in chlorophyll pigments and other organic matrices the SPE method suffers a number of drawbacks, including cartridge clogging, long procedural steps and use of larger volumes of extraction solvents. We applied a supported liquid membrane (SLM) based technique as an alternative sample clean-up method for LC-ESI-MS analysis of MCs from both water and algal cells. Four (4) MC variants (MC-RR, -YR, -LR and -WR) from lyophilized cells of Microcystis aeruginosa and water collected from a wastewater pond were identified) and quantified using LC-ESI-MS following a SLM extraction and liquid partitioning step, however, MC-WR was not detected from water extracts. Within 45 min of SLM extraction all studied MCs were extracted and pre-concentrated in approximately 15 μL of an acceptor phase at an optimal pH 2.02 of the donor phase (sample). The highest

  15. Monitoring pesticide residues in greenhouse tomato by combining acetonitrile-based extraction with dispersive liquid-liquid microextraction followed by gas-chromatography-mass spectrometry.

    PubMed

    Melo, Armindo; Cunha, Sara C; Mansilha, Catarina; Aguiar, Ana; Pinho, Olívia; Ferreira, Isabel M P L V O

    2012-12-01

    A multiclass and multiresidue method for pesticide analysis in tomato was validated. Extraction and pre-concentration of the pesticide residues from acetonitrile extracts was performed by using dispersive liquid-liquid microextraction (DLLME) technique, followed by gas chromatography-mass detection. DLLME was performed using carbon tetrachloride as extractive solvent and acetonitrile extract as dispersive solvent, in order to increase enrichment factor of the extraction procedure. Validation parameters indicated the suitability of the method for routine analyses of thirty pesticides in a large number of samples. In general, pesticide recoveries ranged between 70% and 110% and repeatability ranged between 1% and 20%. The proposed method was applied to the monitoring of pesticides in tomatoes grown during winter in greenhouses. Among the compounds considered in this work, cyprodinil was found in tomato at concentrations of 0.33mg/kg, other pesticides like azoxystrobin, fenhexanid, tolyfluanid, λ-cyhalothrin and trifloxystrobin were also detected, but, not quantified.

  16. Determination of chlorpyrifos in air, leaves and soil from a greenhouse by gas-chromatography with nitrogen-phosphorus detection, high-performance liquid chromatography and capillary electrophoresis.

    PubMed

    Guardino, X; Obiols, J; Rosell, M G; Farran, A; Serra, C

    1998-10-01

    Chlorpyrifos was determined in air, leaves and soil in a greenhouse in order to establish performance differences between gas-chromatography with nitrogen-phosphorus detection (GC-NPD) and high-performance liquid chromatographic and capillary electrophoretic methods and to assess the farm workers' risk of overexposure due to air exposure and/or skin contact with this compound. Results obtained indicate that the three analytical techniques, with the specific procedures described, can be used, although only GC-NPD provides an operative limit of detection in air. Chlorpyrifos levels in air are dependent on time and greenhouse ventilation, whereas it remains for a long time on leaf surfaces and soil. As a consequence, specific instructions can be established for farm workers in order to avoid skin and respiratory exposure to chlorpyrifos.

  17. Characterization of sodium carboxymethyl cellulose by comprehensive two-dimensional liquid chromatography.

    PubMed

    Shakun, Maria; Heinze, Thomas; Radke, Wolfgang

    2015-10-01

    Two series of sodium carboxymethyl celluloses (NaCMC) with average degrees of substitution (DS) ranging from 0.45 to 1.55 were synthesized from low molecular mass Avicel cellulose (Avicel samples) and from high molecular mass cotton linters (BWL samples). The samples were characterized by online two-dimensional liquid chromatography using gradient liquid adsorption chromatography in the first and size exclusion chromatography (SEC) in the second dimension. This method allows the simultaneous determination of the chemical composition (DS) and the molar mass distribution within the individual samples. Moreover information was obtained on the dependence of the elution volume in gradient chromatography on molar mass. As expected, evidence for a stronger influence of molar mass on gradient elution volume was found for the low molecular mass NaCMC as compared to the high molecular mass BWL samples. Finally the applicability of the method for the simultaneous separation of blends heterogeneous with respect to chemical composition (DS) and molar mass was demonstrated. Such blends cannot be efficiently separated by either SEC or gradient chromatography alone, nor by simply combining the results of both methods. Only the complete two-dimensional chromatogram can reveal the complexity of such blends, since it reveals the correlations between molar mass and chemical composition.

  18. Determination of oxidized phosphatidylcholines by hydrophilic interaction liquid chromatography coupled to Fourier transform mass spectrometry.

    PubMed

    Sala, Pia; Pötz, Sandra; Brunner, Martina; Trötzmüller, Martin; Fauland, Alexander; Triebl, Alexander; Hartler, Jürgen; Lankmayr, Ernst; Köfeler, Harald C

    2015-04-14

    A novel liquid chromatography-mass spectrometry (LC-MS) approach for analysis of oxidized phosphatidylcholines by an Orbitrap Fourier Transform mass spectrometer in positive electrospray ionization (ESI) coupled to hydrophilic interaction liquid chromatography (HILIC) was developed. This method depends on three selectivity criteria for separation and identification: retention time, exact mass at a resolution of 100,000 and collision induced dissociation (CID) fragment spectra in a linear ion trap. The process of chromatography development showed the best separation properties with a silica-based Kinetex column. This type of chromatography was able to separate all major lipid classes expected in mammalian samples, yielding increased sensitivity of oxidized phosphatidylcholines over reversed phase chromatography. Identification of molecular species was achieved by exact mass on intact molecular ions and CID tandem mass spectra containing characteristic fragments. Due to a lack of commercially available standards, method development was performed with copper induced oxidation products of palmitoyl-arachidonoyl-phosphatidylcholine, which resulted in a plethora of lipid species oxidized at the arachidonoyl moiety. Validation of the method was done with copper oxidized human low-density lipoprotein (LDL) prepared by ultracentrifugation. In these LDL samples we could identify 46 oxidized molecular phosphatidylcholine species out of 99 possible candidates.

  19. Assessment of dispersive liquid-liquid microextraction conditions for gas chromatography time-of-flight mass spectrometry identification of organic compounds in honey.

    PubMed

    Moniruzzaman, M; Rodríguez, I; Rodríguez-Cabo, T; Cela, R; Sulaiman, S A; Gan, S H

    2014-11-14

    The suitability of the dispersive liquid-liquid microextraction (DLLME) technique for gas chromatography (GC) characterization of minor organic compounds in honey samples is evaluated. Under optimized conditions, samples were pre-treated by liquid-liquid extraction with acetonitrile followed by DLLME using carbon tetrachloride (CCl4, 0.075 mL) as extractant. The yielded settled phase was analyzed by GC using high resolution time-of-flight (TOF) mass spectrometry (MS). The whole sample preparation process is completed in approximately 10 min, with a total consumption of organic solvents below 4 mL, relative standard deviations lower than 12% and with more than 70 organic compounds, displaying linear retention index in the range from 990 to 2900, identified in the obtained extracts. In comparison with HS SPME extraction, higher peak intensities were attained for most volatile and semi-volatile compounds amenable to both extraction techniques. Furthermore, other species such as highly polar and water soluble benzene acids, long chain fatty acids, esters and flavonoids, which are difficult to concentrate by HS SPME, could be identified in DLLME extracts. Some of the compounds identified in DLLME extracts have been proposed as useful for samples classification and/or they are recognized as markers of honeys from certain geographic areas. PMID:25441341

  20. Assessment of dispersive liquid-liquid microextraction conditions for gas chromatography time-of-flight mass spectrometry identification of organic compounds in honey.

    PubMed

    Moniruzzaman, M; Rodríguez, I; Rodríguez-Cabo, T; Cela, R; Sulaiman, S A; Gan, S H

    2014-11-14

    The suitability of the dispersive liquid-liquid microextraction (DLLME) technique for gas chromatography (GC) characterization of minor organic compounds in honey samples is evaluated. Under optimized conditions, samples were pre-treated by liquid-liquid extraction with acetonitrile followed by DLLME using carbon tetrachloride (CCl4, 0.075 mL) as extractant. The yielded settled phase was analyzed by GC using high resolution time-of-flight (TOF) mass spectrometry (MS). The whole sample preparation process is completed in approximately 10 min, with a total consumption of organic solvents below 4 mL, relative standard deviations lower than 12% and with more than 70 organic compounds, displaying linear retention index in the range from 990 to 2900, identified in the obtained extracts. In comparison with HS SPME extraction, higher peak intensities were attained for most volatile and semi-volatile compounds amenable to both extraction techniques. Furthermore, other species such as highly polar and water soluble benzene acids, long chain fatty acids, esters and flavonoids, which are difficult to concentrate by HS SPME, could be identified in DLLME extracts. Some of the compounds identified in DLLME extracts have been proposed as useful for samples classification and/or they are recognized as markers of honeys from certain geographic areas.

  1. Simultaneous determination of seven anticoagulant rodenticides in agricultural products by gel permeation chromatography and liquid chromatography-tandem mass spectrometry.

    PubMed

    Saito-Shida, Shizuka; Nemoto, Satoru; Matsuda, Rieko; Akiyama, Hiroshi

    2016-11-01

    A sensitive and reliable method for the simultaneous determination of hydroxycoumarin-type (brodifacoum, bromadiolone, coumatetralyl, and warfarin) and indandione-type (chlorophacinone, diphacinone, and pindone) rodenticides in agricultural products by gel permeation chromatography (GPC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. The procedure involved extraction of the rodenticides from samples with acetone, followed by liquid-liquid partitioning with hexane/ethyl acetate (1:1, v/v) and 10% sodium chloride aqueous solution, then cleanup using GPC, and finally, analysis using LC-MS/MS. High recoveries from the GPC column were obtained for all rodenticides tested using a mobile phase of acetone/cyclohexane/triethylamine (400:1600:1, v/v/v). An ODS column, which contains low levels of metal impurities, gave satisfactory peak shapes for both hydroxycoumarin- and indandione-type rodenticides in the LC-MS/MS separation. The average recoveries of rodenticides from eight agricultural foods (apple, eggplant, cabbage, orange, potato, tomato, brown rice, and soybean) fortified at 0.0005-0.001 mg/kg ranged from 76 to 116%, except for bromadiolone in orange (53%) and diphacinone in soybean (54%), and the relative standard deviations ranged from 1 to 16%. The proposed method effectively removed interfering components, such as pigments and lipids, and showed high selectivity. In addition, the matrix effects were negligible for most of the rodenticide/food combinations. The results suggest that the proposed method is reliable and suitable for determining hydroxycoumarin- and indandione-type rodenticides in agricultural products. PMID:27428755

  2. Evaluation of gardenia yellow using crocetin from alkaline hydrolysis based on ultra high performance liquid chromatography and high-speed countercurrent chromatography.

    PubMed

    Inoue, Koichi; Tanada, Chihiro; Nishikawa, Hiroaki; Matsuda, Satoru; Tada, Atsuko; Ito, Yusai; Min, Jun Zhe; Todoroki, Kenichiro; Sugimoto, Naoki; Toyo'oka, Toshimasa; Akiyama, Hiroshi

    2014-12-01

    Gardenia yellow is globally the most valuable spice and food color. It is generally a mixture of water-soluble carotenoid glycosyl esters which consist of crocetin bis(gentiobiosyl) ester as the main component. Crocetin is a natural carotenoid dicarboxylic acid that may be a candidate drug for pharmaceutical development, however, it is either present in trace amounts or is absent in natural gardenia yellow products. We here propose that crocetin produced by alkaline hydrolysis can be used to qualitatively evaluate gardenia yellow products using an ultra high performance liquid chromatographic assay. A useful and efficient isolation technique for isolating high-purity crocetin from gardenia yellow using high-speed countercurrent chromatography is described. High-speed countercurrent chromatographic fractionation followed by an ultra high performance liquid chromatographic assay showed that trans-crocetin is easily converted to about 15% cis-crocetin (85% trans-crocetin). Crocetin in gardenia yellow was quantitatively evaluated. Our approach is based on the hydrolysis process for converting crocetin glycosyl esters to crocetin before evaluation and isolation using the ultra high performance liquid chromatographic and high-speed countercurrent chromatographic methods. The combination of hydrolysis and chromatographic methods allows evaluation of the purity and quantity of crocetin in gardenia yellow.

  3. Forensic analysis of ignitable liquids in fire debris by comprehensive two-dimensional gas chromatography.

    PubMed

    Frysinger, Glenn S; Gaines, Richard B

    2002-05-01

    The application of comprehensive two-dimensional gas chromatography (GC x GC) for the forensic analysis of ignitable liquids in fire debris is reported. GC x GC is a high resolution, multidimensional gas chromatographic method in which each component of a complex mixture is subjected to two independent chromatographic separations. The high resolving power of GC x GC can separate hundreds of chemical components from a complex fire debris extract. The GC x GC chromatogram is a multicolor plot of two-dimensional retention time and detector signal intensity that is well suited for rapid identification and fingerprinting of ignitable liquids. GC x GC chromatograms were used to identify and classify ignitable liquids, detect minor differences between similar ignitable liquids, track the chemical changes associated with weathering, characterize the chemical composition of fire debris pyrolysates, and detect weathered ignitable liquids against a background of fire debris pyrolysates.

  4. A regularization method for the reconstruction of adsorption isotherms in liquid chromatography

    NASA Astrophysics Data System (ADS)

    Zhang, Ye; Lin, Guang-Liang; Forssén, Patrik; Gulliksson, Mårten; Fornstedt, Torgny; Cheng, Xiao-Liang

    2016-10-01

    Determining competitive adsorption isotherms is an open problem in liquid chromatography. Since traditional experimental trial-and-error approaches are too complex and expensive, a modern technique of obtaining adsorption isotherms is to solve the inverse problem so that the simulated batch separation coincides with actual experimental results. This is a typical ill-posed problem. Moreover, in almost all cases the observed concentration at the outlet is the total response of all components, which makes the problem more difficult. In this work, we tackle the ill-posedness with a new regularization method, which is based on the fact that the adsorption isotherms do not depend on the injection profile. The proposed method transfers the original problem to an optimization problem with a time-dependent convection-diffusion equation constraint. Iterative algorithms for solving constraint optimization problems for both the equilibrium-dispersive and the transport-dispersive models are developed. The mass transfer resistance is also estimated by the proposed inverse method. A regularization parameter selection method and the convergence property of the proposed algorithm are discussed. Finally, numerical tests for both synthetic problems and real-world problems are given to show the efficiency and feasibility of the proposed regularization method.

  5. Determination of nivalenol and deoxynivalenol by liquid chromatography/atmospheric pressure photoionization mass spectrometry.

    PubMed

    Tanaka, Hiroki; Takino, Masahiko; Sugita-Konishi, Yoshiko; Tanaka, Toshitsugu; Toriba, Akira; Hayakawa, Kazuichi

    2009-10-01

    Fusarium species, a plant pathogenic fungus of wheat and other cereals, produces toxic metabolites such as nivalenol (NIV) and deoxynivalenol (DON). Control of contamination by these toxins is very difficult, and a continuous survey of the occurrence is necessary for these toxins. Thus, the accurate and convenient determination of the cereals contaminated with these toxins is important for the supply of safe foods. A selective analytical method based on high-performance liquid chromatography, combined with atmospheric pressure photoionization (APPI) mass spectrometry, has been developed for simultaneous determination of NIV and DON. The parameters investigated for the optimization of APPI were the ion source parameters fragmentor voltage, capillary voltage, and vaporizer temperature, and also mobile phase composition and flow rate. Furthermore, chemical noise and signal suppression of analyte signals due to sample matrix interference were investigated for APPI. The results indicated that APPI provides lower matrix effect and the correlation coefficient of NIV and DON in the range 0.2-100 ng x mL(-1) was above 0.999. Recoveries of NIV and DON in wheat ranged from 86 to 107% and limits of detection of NIV and DON were 0.20 ng x g(-1) and 0.39 ng x g(-1), respectively. In addition, the proposed method was applied for the analysis of naturally contaminated wheat samples. APPI was found to offer lower matrix effect and was a convenient technique for routine analysis of NIV and DON residues in wheat at trace levels.

  6. Separation of bimodal high density polyethylene using multidimensional high temperature liquid chromatography.

    PubMed

    Prabhu, K N; Brüll, R; Macko, T; Remerie, K; Tacx, J; Garg, P; Ginzburg, A

    2015-11-01

    High-temperature two-dimensional liquid chromatography (HT 2D-LC) using HT-HPLC as first dimension and HT-SEC as second dimension holds enormous potential to investigate the distribution according to molar mass and chemical composition of bimodal high density polyethylene (BiHDPE), as it avoids drawbacks of crystallization-based techniques. In this study, we have stepwise optimized the chromatographic parameters of 1D, comprising gradient slope and temperature, using model homo- and copolymers of ethylene with the aim to minimize the impact of molar mass on the compositional separation. Then the HT-HPLC was hyphenated to HT-SEC and optimum conditions for the volume of the sample transfer loop were probed with regard to the resolution of BiHDPE into the individual constituents HDPE and LLDPE. A particular important aspect was the use of infrared (IR) detection, and the demands it puts on the chromatographic aspects: We have shown that IR detection can be successfully applied in HT 2D-LC of BiHDPE, which is broadly distributed with regard to short chain branching and molar mass, only when the separation in 2D is optimized with regard to chromatographic resolution. As final result a bimodality is evident in the contour and the 3D surface plots as well as in both HPLC and SEC projections generated from HT 2D-LC. PMID:26435312

  7. Global Analysis of the Membrane Subproteome of Pseudomonas aeruginosa using Liquid Chromatography-Tandem Mass Spectrometry

    SciTech Connect

    Blonder, Josip; Goshe, Michael B.; Xiao, Wenzhong; Camp, David G.; Wingerd, Mark A.; Davis, Ronald W.; Smith, Richard D.

    2004-05-30

    Pseudomonas aeruginosa is one of the most significant opportunistic bacterial pathogens in humans causing infections and premature death in patients with cystic fibrosis, AIDS, severe burns, organ transplants or cancer. Liquid chromatography coupled online with tandem mass spectrometry (LC-MS/MS) was used for the large-scale proteomic analysis of the P. aeruginosa membrane subproteome. Concomitantly, an affinity labeling technique, using iodoacetyl-PEO biotin to tag cysteinyl-containing proteins, permitted the enrichment and detection of lower abundance membrane proteins. The application of these approaches resulted in the identification of 786 proteins. A total of 333 proteins (42%) had a minimum of one transmembrane domain (TMD; ranging from 1 to 14) and 195 proteins were classified as hydrophobic based on their positive GRAVY values (ranging from 0.01 to 1.32). Key integral inner and outer membrane proteins involved in adaptation and antibiotic resistance were conclusively identified, including the detection of 53% of all predicted opr-type porins (outer integral membrane proteins) and all the components of the mexA-mexB-oprM transmembrane protein complex. This work represents the most comprehensive qualitative proteomic analysis of the membrane subproteome of P. aeruginosa and for prokaryotes in general to date.

  8. Identification and quantification of glucosinolates in rapeseed using liquid chromatography-ion trap mass spectrometry.

    PubMed

    Millán, Silvia; Sampedro, M Carmen; Gallejones, Patricia; Castellón, Ander; Ibargoitia, Maria L; Goicolea, M Aranzazu; Barrio, Ramón J

    2009-07-01

    A rapid and sensitive method for the speciation and quantification of glucosinolates in rapeseed is described. The method combines liquid chromatography (LC) with ion trap mass spectrometry (ITMS) detection. Electrospray ionization (ESI) has been chosen as the ionization technique for the on-line coupling of LC with ITMS. Glucosinolates are extracted from different rapeseeds with MeOH and the extracts are cleaned-up by solid phase extraction with Florisil cartridges. Aqueous extracts are injected into LC system coupled to an ITMS, leading to accurately quantify eight of the most important glucosinolates in rapeseed, by MS2 mode and confirming their structure by MS3 acquisition. All the glucosinolates found in rapeseeds provide good signals corresponding to the deprotonated precursor ion [M-H]-. The method is reliable and reproducible, and detection limits range from 0.5 nmol g(-1) to 3.7 nmol g(-1) when 200 mg of dried seeds of certified reference material are analyzed. Within-day and between-day RSD percentages range between 2.4-14.1% and 3.9-16.9%, respectively. The LC-ESI-ITMS-MS method described here allows for a rapid assessment of these metabolites in rapeseed without a desulfatation step. The overall process has been successfully applied to identify and quantify glucosinolates in rapeseed samples.

  9. Simultaneous liquid chromatography-mass spectrometry quantification of cefixime and clavulanic acid in human plasma.

    PubMed

    Dubala, Anil; Nagarajan, Janaki Sankarachari Krishnan; Vimal, Chandran Sathish; George, Renjith

    2015-01-01

    A simple and specific liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS) assay method has been developed and fully validated for the simultaneous quantification of cefixime (CX) and clavulanic acid (CA) in human plasma. Analytes and internal standard were extracted from human plasma by a solid phase extraction technique using a Sam prep (3 mL, 100 mg) extraction cartridge. The extracted samples were chromatographed on a reverse phase C18 column using a mixture of methanol : acetonitrile : 2 mM ammonium acetate (pH 3.5) (25 : 25 : 50, v/v/v) as the mobile phase at a flow rate of 0.8 mL/min. Quantification of the analytes were carried out using single quadrupole LC-APCI-MS through selected ion monitoring at m/z 452 and 198, respectively, for CX and CA. The assay was linear over the concentration range of 0.05-10.0 and 0.1-10.0 μg/mL, respectively, for CX and CA. The mean plasma extraction recoveries of the CX and CA were found to be 95.20-96.27% and 94.67-95.58%, respectively. The method was successfully applied for the determination of pharmacokinetics of CX and CA after oral administration of single dosage CX/CA (200/125 mg) pill to the humans (n = 12).

  10. Separation of bimodal high density polyethylene using multidimensional high temperature liquid chromatography.

    PubMed

    Prabhu, K N; Brüll, R; Macko, T; Remerie, K; Tacx, J; Garg, P; Ginzburg, A

    2015-11-01

    High-temperature two-dimensional liquid chromatography (HT 2D-LC) using HT-HPLC as first dimension and HT-SEC as second dimension holds enormous potential to investigate the distribution according to molar mass and chemical composition of bimodal high density polyethylene (BiHDPE), as it avoids drawbacks of crystallization-based techniques. In this study, we have stepwise optimized the chromatographic parameters of 1D, comprising gradient slope and temperature, using model homo- and copolymers of ethylene with the aim to minimize the impact of molar mass on the compositional separation. Then the HT-HPLC was hyphenated to HT-SEC and optimum conditions for the volume of the sample transfer loop were probed with regard to the resolution of BiHDPE into the individual constituents HDPE and LLDPE. A particular important aspect was the use of infrared (IR) detection, and the demands it puts on the chromatographic aspects: We have shown that IR detection can be successfully applied in HT 2D-LC of BiHDPE, which is broadly distributed with regard to short chain branching and molar mass, only when the separation in 2D is optimized with regard to chromatographic resolution. As final result a bimodality is evident in the contour and the 3D surface plots as well as in both HPLC and SEC projections generated from HT 2D-LC.

  11. Partial enzymatic elimination and quantification of sarcosine from alanine using liquid chromatography-tandem mass spectrometry.

    PubMed

    Burton, Casey; Gamagedara, Sanjeewa; Ma, Yinfa

    2013-04-01

    Since sarcosine and D,L-alanine co-elute on reversed-phase high-performance liquid chromatography (HPLC) columns and the tandem mass spectrometer cannot differentiate them due to equivalent parent and fragment ions, derivatization is often required for analysis of sarcosine in LC/MS systems. This study offers an alternative to derivatization by employing partial elimination of sarcosine by enzymatic oxidation. The decrease in apparent concentration from the traditionally merged sarcosine-alanine peak associated with the enzymatic elimination has been shown to be proportional to the total sarcosine present (R(2) = 0.9999), allowing for determinations of urinary sarcosine. Sarcosine oxidase was shown to eliminate only sarcosine in the presence of D,L-alanine, and was consequently used as the selective enzyme. This newly developed technique has a method detection limit of 1 μg/L (parts per billion) with a linear range of 3 ppb-1 mg/L (parts per million) in urine matrices. The method was further validated through spiked recoveries of real urine samples, as well as the analysis of 35 real urine samples. The average recoveries for low, middle, and high sarcosine concentration spikes were 111.7, 90.8, and 90.1 %, respectively. In conclusion, this simple enzymatic approach coupled with HPLC/MS/MS is able to resolve sarcosine from D,L-alanine leading to underivatized quantification of sarcosine.

  12. Optimization of large-scale pseudotargeted metabolomics method based on liquid chromatography-mass spectrometry.

    PubMed

    Luo, Ping; Yin, Peiyuan; Zhang, Weijian; Zhou, Lina; Lu, Xin; Lin, Xiaohui; Xu, Guowang

    2016-03-11

    Liquid chromatography-mass spectrometry (LC-MS) is now a main stream technique for large-scale metabolic phenotyping to obtain a better understanding of genomic functions. However, repeatability is still an essential issue for the LC-MS based methods, and convincing strategies for long time analysis are urgently required. Our former reported pseudotargeted method which combines nontargeted and targeted analyses, is proved to be a practical approach with high-quality and information-rich data. In this study, we developed a comprehensive strategy based on the pseudotargeted analysis by integrating blank-wash, pooled quality control (QC) sample, and post-calibration for the large-scale metabolomics study. The performance of strategy was optimized from both pre- and post-acquisition sections including the selection of QC samples, insertion frequency of QC samples, and post-calibration methods. These results imply that the pseudotargeted method is rather stable and suitable for large-scale study of metabolic profiling. As a proof of concept, the proposed strategy was applied to the combination of 3 independent batches within a time span of 5 weeks, and generated about 54% of the features with coefficient of variations (CV) below 15%. Moreover, the stability and maximal capability of a single analytical batch could be extended to at least 282 injections (about 110h) while still providing excellent stability, the CV of 63% metabolic features was less than 15%. Taken together, the improved repeatability of our strategy provides a reliable protocol for large-scale metabolomics studies.

  13. Characterization of isoflavone composition in soy-based nutritional supplements via ultra performance liquid chromatography.

    PubMed

    Fiechter, G; Raba, B; Jungmayr, A; Mayer, H K

    2010-07-01

    The specific isoflavone composition of nutritional supplements is commonly not-labeled, although the stated amounts are strongly dependent on the present isoflavone conjugates. Hence, 11 soy-based dietary supplements were characterized via a newly established ultra performance liquid chromatography (UPLC) method, on both their native conjugated isoflavone spectra, as well as on quantitative amounts derived as total aglycones after enzymatic hydrolysis utilizing Helix pomatia juice. Capitalizing on sub-2 microm particles, the established RP-UPLC technique facilitated efficient chromatographic separation of all 12 soy intrinsic isoflavone forms within 10 min. Derived native isoflavone profiles implied a certain variability, comprising conjugated forms, especially glycosides, as the predominant isoflavonic constituents throughout the majority of supplements, whereas only two samples indicated the more bioavailable free aglycones as prevailing compounds. Moreover, the robust quantification as total aglycones subsequent to enzymatic hydrolysis, unexceptionally yielded negative deviations referring to the labeled specifications, thus implying that stated amounts were typically calculated on basis of the high molecular isoflavone conjugates. Thus, especially in regard to better comparability, regulations concerning an uniform labeling basis are needed.

  14. A validated method for analysis of Swerchirin in Swertia longifolia Boiss. by high performance liquid chromatography

    PubMed Central

    Shekarchi, M.; Hajimehdipoor, H.; Khanavi, M.; Adib, N.; Bozorgi, M.; Akbari-Adergani, B.

    2010-01-01

    Swertia spp. (Gentianaceae) grow widely in the eastern and southern Asian countries and are used as traditional medicine for gastrointestinal disorders. Swerchirin, one of the xanthones in Swertia spp., has many pharmacological properties, such as, antimalarial, antihepatotoxic, and hypoglycemic effects. Because of the pharmacological importance of Swerchirin in this investigation, it was purified from Swertia longifolia Boiss. as one of the main components and quantified by means of a validated high performance liquid chromatography (HPLC) technique. Aerial parts of the plant were extracted with acetone 80%. Phenolic and non-phenolic constituents of the extract were separated from each other during several processes. The phenolic fraction was injected into the semi-preparative HPLC system, which consisted of a C18 column and a gradient methanol: 0.1% formic acid mode. Using this method, we were able to purify six xanthones from the plant, in order to use them as standard materials. The analytical method was validated for Swerchirin as one of the most important components of the plant, with more pharmacological activities according to the validation parameters, such as, selectivity, linearity (r2 > 0.9998), precision (≤3.3), and accuracy, which were measured by the determination of recovery (98-107%). The limits of detection and quantization were found to be 2.1 and 6.3 μg/mL, respectively. On account of the speed and accuracy, the UV-HPLC method may be used for quantitative analysis of Swerchirin. PMID:20548931

  15. High Throughput Quantitative Analysis of Serum Proteins Using Glycopeptide Capture and Liquid Chromatography Mass Spectrometry

    SciTech Connect

    Zhang, Hui; Yi, Eugene C.; Li, Xiao-jun; Mallick, Parag; Kelly-Spratt, Karen S.; Masselon, Christophe D.; Camp, David G.; Smith, Richard D.; Kemp, Christopher J.; Aebersold, Reudi

    2005-02-01

    It is expected that the composition of the serum proteome can provide valuable information about the state of the human body in health and disease and that this information can be extracted via quantitative proteomic measurements. Suitable proteomic techniques need to be sensitive, reproducible, and robust to detect potential biomarkers below the level of highly expressed proteins, generate data sets that are comparable between experiments and laboratories, and have high throughput to support statistical studies. Here we report a method for high throughput quantitative analysis of serum proteins. It consists of the selective isolation of peptides that are N-linked glycosylated in the intact protein, the analysis of these now deglycosylated peptides by liquid chromatography electrospray ionization mass spectrometry, and the comparative analysis of the resulting patterns. By focusing selectively on a few formerly N-linked glycopeptides per serum protein, the complexity of the analyte sample is significantly reduced and the sensitivity and throughput of serum proteome analysis are increased compared with the analysis of total tryptic peptides from unfractionated samples. We provide data that document the performance of the method and show that sera from untreated normal mice and genetically identical mice with carcinogen-induced skin cancer can be unambiguously discriminated using unsupervised clustering of the resulting peptide patterns. We further identify, by tandem mass spectrometry, some of the peptides that were consistently elevated in cancer mice compared with their control littermates.

  16. Quality Evaluation of Potentilla fruticosa L. by High Performance Liquid Chromatography Fingerprinting Associated with Chemometric Methods

    PubMed Central

    Liu, Wei; Wang, Dongmei; Liu, Jianjun; Li, Dengwu; Yin, Dongxue

    2016-01-01

    The present study was performed to assess the quality of Potentilla fruticosa L. sampled from distinct regions of China using high performance liquid chromatography (HPLC) fingerprinting coupled with a suite of chemometric methods. For this quantitative analysis, the main active phytochemical compositions and the antioxidant activity in P. fruticosa were also investigated. Considering the high percentages and antioxidant activities of phytochemicals, P. fruticosa samples from Kangding, Sichuan were selected as the most valuable raw materials. Similarity analysis (SA) of HPLC fingerprints, hierarchical cluster analysis (HCA), principle component analysis (PCA), and discriminant analysis (DA) were further employed to provide accurate classification and quality estimates of P. fruticosa. Two principal components (PCs) were collected by PCA. PC1 separated samples from Kangding, Sichuan, capturing 57.64% of the variance, whereas PC2 contributed to further separation, capturing 18.97% of the variance. Two kinds of discriminant functions with a 100% discrimination ratio were constructed. The results strongly supported the conclusion that the eight samples from different regions were clustered into three major groups, corresponding with their morphological classification, for which HPLC analysis confirmed the considerable variation in phytochemical compositions and that P. fruticosa samples from Kangding, Sichuan were of high quality. The results of SA, HCA, PCA, and DA were in agreement and performed well for the quality assessment of P. fruticosa. Consequently, HPLC fingerprinting coupled with chemometric techniques provides a highly flexible and reliable method for the quality evaluation of traditional Chinese medicines. PMID:26890416

  17. Retention mechanism for polycyclic aromatic hydrocarbons in reversed-phase liquid chromatography with monomeric stationary phases.

    PubMed

    Rafferty, Jake L; Siepmann, J Ilja; Schure, Mark R

    2011-12-23

    Reversed-phase liquid chromatography (RPLC) is the foremost technique for the separation of analytes that have very similar chemical functionalities, but differ only in their molecular shape. This ability is crucial in the analysis of various mixtures with environmental and biological importance including polycyclic aromatic hydrocarbons (PAHs) and steroids. A large amount of effort has been devoted to studying this phenomenon experimentally, but a detailed molecular-level description remains lacking. To provide some insight on the mechanism of shape selectivity in RPLC, particle-based simulations were carried out for stationary phases and chromatographic parameters that closely mimic those in an experimental study by Sentell and Dorsey [J. Chromatogr. 461 (1989) 193]. The retention of aromatic hydrocarbons ranging in size from benzene to the isomeric PAHs of the formula C(18)H(12) was examined for model RPLC systems consisting of monomeric dimethyl octadecylsilane (ODS) stationary phases with surface coverages ranging from 1.6 to 4.2 μmol/m(2) (i.e., stationary phases yielding low to intermediate shape selectivity) in contact with a 67/33 mol% acetonitrile/water mobile phase. The simulations show that the stationary phase acts as a very heterogeneous environment where analytes with different shapes prefer different spatial regions with specific local bonding environments of the ODS chains. However, these favorable retentive regions cannot be described as pre-existing cavities because the chain conformation in these local stationary phase regions adapts to accommodate the analytes.

  18. Identification and quantitation of asparagine and citrulline using high-performance liquid chromatography (HPLC).

    PubMed

    Bai, Cheng; Reilly, Charles C; Wood, Bruce W

    2007-01-01

    High-performance liquid chromatography (HPLC) analysis was used for identification of two problematic ureides, asparagine and citrulline. We report here a technique that takes advantage of the predictable delay in retention time of the co-asparagine/citrulline peak to enable both qualitative and quantitative analysis of asparagine and citrulline using the Platinum EPS reverse-phase C18 column (Alltech Associates). Asparagine alone is eluted earlier than citrulline alone, but when both of them are present in biological samples they may co-elute. HPLC retention times for asparagine and citrulline were influenced by other ureides in the mixture. We found that at various asparagines and citrulline ratios [= 3:1, 1:1, and 1:3; corresponding to 75:25, 50:50, and 25:75 (microMol ml(-1)/microMol ml(-1))], the resulting peak exhibited different retention times. Adjustment of ureide ratios as internal standards enables peak identification and quantification. Both chemicals were quantified in xylem sap samples of pecan [Carya illinoinensis (Wangenh.) K. Koch] trees. Analysis revealed that tree nickel nutrition status affects relative concentrations of Urea Cycle intermediates, asparagine and citrulline, present in sap. Consequently, we concluded that the HPLC methods are presented to enable qualitative and quantitative analysis of these metabolically important ureides. PMID:19662174

  19. 234Th analysis of marine sediments via extraction chromatography and liquid scintillation counting.

    PubMed

    Nour, Svetlana; Burnett, William C; Horwitz, E Philip

    2002-08-01

    234Th is widely used as a natural tracer for study of biological mixing and particle scavenging processes in the ocean. This naturally occurring nuclide serves this purpose due to its convenient half-life (24.1 days), constant rate of production from 238U dissolved in seawater, and its strong tendency to attach to particles in seawater. As a beta/gamma emitter, 234Th may be determined using low-level gas-flow proportional counting, gamma spectrometry, and liquid scintillation counting (LSC). We describe here a technique which combines Cerenkov counting to evaluate 234Th (via 234Pa) with LSC alpha counting of 230Th added to the samples as a yield tracer. Our separation approach is based on a sample preparation procedure for marine sediments using nitric acid leaching in a "hot block", and extraction chromatography (TEVA x Resin) for Th isolation. Samples are counted in plastic LSC vials, using Ultima Gold AB cocktail, in 1 M H3PO4 media. A series of sediment samples spiked with known amounts of 234Th yielded activities within a few percent of the anticipated values. PMID:12150283

  20. Development of MEMS-based liquid chromatography modules for agrofood applications

    NASA Astrophysics Data System (ADS)

    Benvenuto, Antonella; Lorenzelli, Leandro; Collini, Cristian; Guarnieri, Vittorio; Adami, Andrea; Morganti, Elisa

    2007-05-01

    This work presents the realization of a MEMS-based miniaturized system for liquid chromatography focused on agrofood applications, and in particular on the detection of wine defects. The main modules of the systems are: i.) a Si-based separation column with inlet/outlet for fluidic connections; ii.) a three-microelectrode voltammetric sensor. Moreover, a Platinum heater has been realized on the back side of the chip containing the Si column in order to operate at temperatures greater than the room temperature. The realized device consists of a Silicon/Pyrex structure realised by anodic bonding. Microchannels and inlet/outlet have been fabricated by Deep Reactive Ion Etching (DRIE) and Tetra Methyl Ammonium Hydroxide (TMAH) wet etching respectively. The column has been functionalised with n-octyltriethoxysilane (C8-TEOS). A lift-off technique has been developed for realizing the Pt heater and the Pt microelectrodes on-chip. In order to separately characterize the main modules of the device, a package of the system has been realized following a modular approach; appropriate tubing and nanovolume connections have been used in order to minimize dead volumes. Then other packages approaches have been considered in order to minimize dead volumes and to avoid leakage issues. Preliminary characterization tests of the two main modules have been performed. The capability of the system to correctly retain and detect Acetic acid has been tested.

  1. Determination of porphyrins in oral bacteria by liquid chromatography electrospray ionization tandem mass spectrometry.

    PubMed

    Fyrestam, Jonas; Bjurshammar, Nadja; Paulsson, Elin; Johannsen, Annsofi; Östman, Conny

    2015-09-01

    Biofilms in the oral cavity can be visualized by fluorescence and a common assumption is that the endogenously produced porphyrins in certain bacteria give rise to this fluorescence. Porphyrin content in oral bacteria has been sparingly investigated, and non-selective detection techniques such as utilizing the Soret fluorescence band of porphyrins are often used. In the present study, a quantitative and selective method for the determination of porphyrins in oral bacteria has been developed and validated using high performance liquid chromatography-tandem mass spectrometry. Lysis of bacteria using Tris-EDTA buffer together with ultrasonication showed high microbial killing efficiency ≥99.98%, and sample clean-up using C18-solid phase extraction resulted in low matrix effects ≤14% for all analytes. Using this method, the porphyrin content was determined in the two oral pathogens Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis, as well as for baker's yeast, Saccharomyces cerevisiae. Uroporphyrin, 7-carboxylporphyrin, 6-carboxylporphyrin, coproporphyrin, and protoporphyrin IX were identified in the investigated microorganisms, and it was shown that the porphyrin profile differs between the two bacteria, as well as for S. cerevisiae. To our knowledge, this is the first time the porphyrin profile has been determined for the bacterium A. actinomycetemcomitans. PMID:26168965

  2. Optical properties of gold and silver nanoclusters investigated by liquid chromatography

    NASA Astrophysics Data System (ADS)

    Wilcoxon, J. P.; Martin, J. E.; Provencio, P.

    2001-07-01

    We report high-pressure liquid chromatography (HPLC) and transmission electron microscopy studies of the size-dependent absorbance properties of Au and Ag nanoclusters dispersed in organic solvents. These nanosize metal clusters are synthesized by an inverse micelle synthetic technique at room temperature in inert oils and those investigated range in diameter from 1.3-8 nm. HPLC allows us to separate the clusters from all other chemicals and size select to a resolution of ±2 Å. We use an on-line photodiode array to study the size-dependent absorbance properties of these clusters. For both Au and Ag clusters in the size range d=8 to d=1.5 nm, the plasmon linewidth broadens following a 1/R linewidth size dependence whose slope is greatest for Au. The peak asymmetry in the plasmon band shape is greatest for Au and increases with decreasing size for both Au and Ag clusters. The plasmon peak energy blue shifts with decreasing size for Au clusters while in the case of Ag nanoclusters a red shift is observed.

  3. Determination of porphyrins in oral bacteria by liquid chromatography electrospray ionization tandem mass spectrometry.

    PubMed

    Fyrestam, Jonas; Bjurshammar, Nadja; Paulsson, Elin; Johannsen, Annsofi; Östman, Conny

    2015-09-01

    Biofilms in the oral cavity can be visualized by fluorescence and a common assumption is that the endogenously produced porphyrins in certain bacteria give rise to this fluorescence. Porphyrin content in oral bacteria has been sparingly investigated, and non-selective detection techniques such as utilizing the Soret fluorescence band of porphyrins are often used. In the present study, a quantitative and selective method for the determination of porphyrins in oral bacteria has been developed and validated using high performance liquid chromatography-tandem mass spectrometry. Lysis of bacteria using Tris-EDTA buffer together with ultrasonication showed high microbial killing efficiency ≥99.98%, and sample clean-up using C18-solid phase extraction resulted in low matrix effects ≤14% for all analytes. Using this method, the porphyrin content was determined in the two oral pathogens Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis, as well as for baker's yeast, Saccharomyces cerevisiae. Uroporphyrin, 7-carboxylporphyrin, 6-carboxylporphyrin, coproporphyrin, and protoporphyrin IX were identified in the investigated microorganisms, and it was shown that the porphyrin profile differs between the two bacteria, as well as for S. cerevisiae. To our knowledge, this is the first time the porphyrin profile has been determined for the bacterium A. actinomycetemcomitans.

  4. [Determination of dyes in cosmetic by high performance liquid chromatography].

    PubMed

    Wang, J; Hu, J

    1999-09-01

    A reversed-phase high performance liquid chromatographic method was used to detect 5 dyes including p-phenylenediamine in cosmetrics. A Zorbax C8 column was used and mobile phase was V (triethanolamine):V(water):V(acetonitrile) = 0.95:94.05:5 adjusted to pH 7.7 by phosphoric acid. The wavelength 280 nm was selected. Samples were extracted with 95% ethanol by ultrasonic method. The recoveries were 87%-107% and the relative standard deviations were 2.3%-6.4%.

  5. Atmospheric-pressure laser ionization: a novel ionization method for liquid chromatography/mass spectrometry.

    PubMed

    Constapel, M; Schellenträger, M; Schmitz, O J; Gäb, S; Brockmann, K J; Giese, R; Benter, Th

    2005-01-01

    We report on the development of a new laser-ionization (LI) source operating at atmospheric pressure (AP) for liquid chromatography/mass spectrometry (LC/MS) applications. APLI is introduced as a powerful addition to existing AP ionization techniques, in particular atmospheric-pressure chemical ionization (APCI), electrospray ionization (ESI), and atmospheric pressure photoionization (APPI). Replacing the one-step VUV approach in APPI with step-wise two-photon ionization strongly enhances the selectivity of the ionization process. Furthermore, the photon flux during an ionization event is drastically increased over that of APPI, leading to very low detection limits. In addition, the APLI mechanism generally operates primarily directly on the analyte. This allows for very efficient ionization even of non-polar compounds such as polycyclic aromatic hydrocarbons (PAHs). The APLI source was characterized with a MicroMass Q-Tof Ultima II analyzer. Both the effluent of an HPLC column containing a number of PAHs (benzo[a]pyrene, fluoranthene, anthracene, fluorene) and samples from direct syringe injection were analyzed with respect to selectivity and sensitivity of the overall system. The liquid phase was vaporized by a conventional APCI inlet (AP probe) with the corona needle removed. Ionization was performed through selective resonance-enhanced multi-photon ionization schemes using a high-repetition-rate fixed-frequency excimer laser operating at 248 nm. Detection limits well within the low-fmol regime are readily obtained for various aromatic hydrocarbons that exhibit long-lived electronic states at the energy level of the first photon. Only molecular ions are generated at the low laser fluxes employed ( approximately 1 MW/cm(2)). The design and performance of the laser-ionization source are presented along with results of the analysis of aromatic hydrocarbons.

  6. Techniques for geothermal liquid sampling and analysis

    SciTech Connect

    Kindle, C.H.; Woodruff, E.M.

    1981-07-01

    A methodology has been developed that is particularly suited to liquid-dominated resources and adaptable to a variety of situations. It is intended to be a base methodology upon which variations can be made to meet specific needs or situations. The approach consists of recording flow conditions at the time of sampling, a specific insertable probe sampling system, a sample stabilization procedure, commercially available laboratory instruments, and data quality check procedures.

  7. Lattice-fluid model for gas-liquid chromatography.

    PubMed

    Tao, Y; Wells, P S; Yi, X; Yun, K S; Parcher, J F

    1999-11-01

    Lattice-fluid models describe molecular ensembles in terms of the number of lattice sites occupied by molecular species (r-mers) and the interactions between neighboring molecules. The lattice-fluid model proposed by Sanchez and Lacombe (Macromolecules, 1978;11:1145-1156) was used to model specific retention volume data for a series of n-alkane solutes with n-alkane, polystyrene, and poly(dimethylsiloxane) stationary liquid phases. Theoretical equations were derived for the specific retention volume and also for the temperature dependence and limiting (high temperature) values for the specific retention volume. The model was used to predict retention volumes within 10% for the n-alkanes phases; 22% for polystyrene; and from 20 to 70% for PDMS using no adjustable parameters. The temperature derivative (enthalpy) could be calculated within 5% for all of the solutes in nine stationary liquid phases. The limiting value for the specific retention volume at high temperature (entropy controlled state) could be calculated within 10% for all of the systems. The limiting data also provided a new chromatographic method to measure the size parameter, r, for any chromatographic solute using characteristic and size parameters for the stationary phase only. The calculated size parameters of the solutes were consistent, i.e. independent of the stationary phase and agreed within experimental error with the size parameters previously reported from saturated vapor pressure, latent heat of vaporization or density data.

  8. Conventional and micellar liquid chromatography method development for danazol and validation in capsules.

    PubMed

    Gonzalo-Lumbreras, R; Izquierdo-Hornillos, R

    2003-07-14

    Two isocratic liquid chromatographic methods (conventional and micellar) for the determination of danazol (DZ) in capsules using canrenone (CAN) as internal standard have been developed and validated. In conventional liquid chromatography a mobile phase 35% water:acetonitrile 65%, v:v, a flow-rate 1 ml min(-1) and a C18 Hypersil ODS (250 x 4.6 mm, 5 microm) column (25 degrees C) were used. In micellar liquid chromatography (MLC) the conditions were: mobile phase 40 mM sodium dodecyl sulfate:2% pentanol, flow-rate 0.5 ml min(-1) and C18 Hypersil ODS (150 x 3.0 mm, 5 microm) column (60 degrees C). For both methods. UV absorbance detection at 280 nm was used and a separation up to base line was achieved. Prior to HPLC analysis a simple sample preparation was required. The recoveries found in the accuracy test were 99 +/- 10 and 101 +/- 8%, in conventional liquid chromatography (CLC) and MLC, respectively. Repeatability and intermediate precision expressed as R.S.D. were lower than 5% for both methods. Detection limits obtained were 2.4 and 3.0 ng g(-1) in CLC and CLM, respectively. PMID:14565547

  9. [An analysis of maicaodi by high performance liquid chromatography].

    PubMed

    Yang, H; Chen, R; Jiang, M

    1997-05-01

    Maicaodi has recently been developed and produced by the pesticide plant of Nanjing Agricultural University. The quantitative analysis of the effective components--tribenuron methyl and R (-)napropamide in wettable powder of Maicaode, by a high performance liquid chromatographic method was carried out with a Lichrosorb Si-60 20cm x 0.46cm i.d. column, mobile phase of petroleum ether/isopropanol/methanol/acetonitrile/chloroform mixture solvent (80:5:5:5:5) and internal standard of diisooctyl phthalate. The sample was detected by ultraviolet absorption at 254 nm. The retention times of tribenuron methyl and R (-)napropamide were 10-11min and 6-7min respectively. The coefficient of variation of this analysis was 0.34% with a recovery of 99.51%-100.32%. The coefficient of linear correlation was 0.9999. PMID:15739379

  10. Magnetic ionic liquid-based dispersive liquid-liquid microextraction for the determination of triazine herbicides in vegetable oils by liquid chromatography.

    PubMed

    Wang, Yuanpeng; Sun, Ying; Xu, Bo; Li, Xinpei; Jin, Rui; Zhang, Hanqi; Song, Daqian

    2014-12-19

    Magnetic ionic liquid-based dispersive liquid-liquid microextraction (MIL-based DLLME) was developed for extracting triazine herbicides from vegetable oils. The MIL, 1-hexyl-3-methylimidazolium tetrachloroferrate ([C6mim] [FeCl4]), was used as the microextraction solvent. The magnetic separation time was shortened by simply mixing carbonyl iron powder with the MIL in the sample after DLLME. The effects of several important experimental parameters, including the amount of MIL, the time of ultrasonic extraction, the type and the volume of cleanup solvent were investigated. The MIL-based DLLME coupled with liquid chromatography gave the limits of detection of 1.31-1.49ngmL(-1) and limits of quantification of 4.33-4.91 ng mL(-1) for triazine herbicides. When the present method was applied to the analysis of vegetable oil samples, the obtained recoveries were in the range of 81.8-114.2% and the relative standard deviations were lower than 7.7%. Compared with existing methods, the performances achieved by the present method were acceptable.

  11. Quantitation of antioxidants in water samples using ionic liquid dispersive liquid-liquid microextraction followed by high-performance liquid chromatography-ultraviolet detection.

    PubMed

    Sobhi, Hamid Reza; Kashtiaray, Amir; Farahani, Hadi; Farahani, Mohammad Reza

    2011-01-01

    A simple and efficient method, ionic liquid-based dispersive liquid-liquid microextraction combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV), has been applied for the extraction and determination of some antioxidants (Irganox 1010, Irganox 1076 and Irgafos 168) in water samples. The microextraction efficiency factors were investigated and optimized: 1-hexyl-3-methylimidazolium hexafluorophosphate [C(6)MIM][PF(6)] (0.06 g) as extracting solvent, methanol (0.5 mL) as disperser solvent without salt addition. Under the selected conditions, enrichment factors up to 48-fold, limits of detection (LODs) of 5.0-10.0 ng/mL and dynamic linear ranges of 25-1500 ng/mL were obtained. A reasonable repeatability (RSD≤11.8%, n=5) with satisfactory linearity (r(2)≥0.9954) of the results illustrated a good performance of the presented method. The accuracy of the method was tested by the relative recovery experiments on spiked samples, with results ranging from 85 to 118%. Finally, the method was successfully applied for determination of the analytes in several real water samples.

  12. Ionic-liquid-based dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography for the forensic determination of methamphetamine in human urine.

    PubMed

    Wang, Ruifeng; Qi, Xiujuan; Zhao, Lei; Liu, Shimin; Gao, Shuang; Ma, Xiangyuan; Deng, Youquan

    2016-07-01

    Determination of methamphetamine in forensic laboratories is a major issue due to its health and social harm. In this work, a simple, sensitive, and environmentally friendly method based on ionic liquid dispersive liquid-liquid microextraction combined with high-performance liquid chromatography was established for the analysis of methamphetamine in human urine. 1-Octyl-3-methylimidazolium hexafluorophosphate with the help of disperser solvent methanol was selected as the microextraction solvent in this process. Various parameters affecting the extraction efficiency of methamphetamine were investigated systemically, including extraction solvent and its volume, disperser solvent and its volume, sample pH, extraction temperature, and centrifugal time. Under the optimized conditions, a good linearity was obtained in the concentration range of 10-1000 ng/mL with determination coefficient >0.99. The limit of detection calculated at a signal-to-noise ratio of 3 was 1.7 ng/mL and the relative standard deviations for six replicate experiments at three different concentration levels of 100, 500, and 1000 ng/mL were 6.4, 4.5, and 4.7%, respectively. Meanwhile, up to 220-fold enrichment factor of methamphetamine and acceptable extraction recovery (>80.0%) could be achieved. Furthermore, this method has been successfully employed for the sensitive detection of a urine sample from a suspected drug abuser.

  13. Direct Measurement of Free Estradiol in Human Serum and Plasma by Equilibrium Dialysis-Liquid Chromatography-Tandem Mass Spectrometry.

    PubMed

    Ray, Julie A; Kushnir, Mark M; Rockwood, Alan L; Meikle, A Wayne

    2016-01-01

    We describe a direct method of measurement of free estradiol using equilibrium dialysis followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Serum aliquots and internal standards are extracted by liquid-liquid extraction using methyl-tert-butyl ether (MTBE) followed by derivatization with dansyl chloride. An API 5500 mass spectrometer operated in positive electrospray mode is used for detection.

  14. Online polar two phase countercurrent chromatography×high performance liquid chromatography for preparative isolation of polar polyphenols from tea extract in a single step.

    PubMed

    Chen, Wei-Bin; Li, Shu-Qi; Chen, Long-Jiang; Fang, Mei-Juan; Chen, Quan-Cheng; Wu, Zhen; Wu, Yun-Long; Qiu, Ying-Kun

    2015-08-01

    Herein, we report an on-line two-dimensional system constructed by counter-current chromatography (CCC) coupling with preparative high-performance liquid chromatography (prep-HPLC) for the separation and purification of polar natural products. The CCC was used as the first dimensional isolation column, where an environmental friendly polar two-phase solvent system of isopropanol and 16% sodium chloride aqueous solution (1:1.2, v/v) was introduced for low toxicity and favorable resolution. In addition, by applying the stop-and-go flow technique, effluents pre-fractionated by CCC was further purified by a preparative column packed with octadecyl silane (ODS) as the second dimension. The interface between the two dimensions was comprised of a 6-port switching valve and an electronically controlled 2-position 10-port switching valve connected with two equivalent holding columns. To be highlighted here, this rationally designed interface for the purpose of smooth desalination, absorption and desorption, successfully solved the solvent compatibility problem between the two dimensional separation systems. The present integrated system was successfully applied in a one-step preparative separation and identification of 10 pure compounds from the water extracts of Tieguanyin tea (Chinese oolong tea). In short, all the results demonstrated that the on-line 2D CCC×LC method is an efficient and green approach for harvesting polar targets in a single step, which showed great promise in drug discovery.

  15. Determination of pesticide residues in samples of green minor crops by gas chromatography and ultra performance liquid chromatography coupled to tandem quadrupole mass spectrometry.

    PubMed

    Walorczyk, Stanisław; Drożdżyński, Dariusz; Kierzek, Roman

    2015-01-01

    A method was developed for pesticide analysis in samples of high chlorophyll content belonging to the group of minor crops. A new type of sorbent, known as ChloroFiltr, was employed for dispersive-solid phase extraction cleanup (dispersive-SPE) to reduce the unwanted matrix background prior to concurrent analysis by gas chromatography and ultra-performance liquid chromatography coupled to tandem quadrupole mass spectrometry (GC-MS/MS and UPLC-MS/MS). Validation experiments were carried out on green, unripe plants of lupin, white mustard and sorghum. The overall recoveries at the three spiking levels of 0.01, 0.05 and 0.5 mg kg(-1) fell in the range between 68 and 120% (98% on average) and 72-104% (93% on average) with relative standard deviation (RSD) values between 2 and 19% (7% on average) and 3-16% (6% on average) by GC-MS/MS and UPLC-MS/MS technique, respectively. Because of strong enhancement or suppression matrix effects (absolute values >20%) which were exhibited by about 80% of the pesticide and matrix combinations, acceptably accurate quantification was achieved by using matrix-matched standards. Up to now, the proposed method has been successfully used to study the dissipation patterns of pesticides after application on lupin, white mustard, soya bean, sunflower and field bean in experimental plot trials conducted in Poland. PMID:25476298

  16. Rhamnolipid biosurfactant analysis using online turbulent flow chromatography-liquid chromatography-tandem mass spectrometry.

    PubMed

    Behrens, Beate; Helmer, Patrick O; Tiso, Till; Blank, Lars M; Hayen, Heiko

    2016-09-23

    Rhamnolipids are biosurfactants produced by a variety of bacterial species that present a promising alternative to surfactants from petrochemical or oleochemical origin. The success of the fermentation is evaluated by subsequent qualitative and quantitative analysis. However, the sample preparation for high numbers of samples is often laborious and inefficient. In this study an online sample preparation is developed for the qualitative and quantitative analysis of rhamnolipids by LC-MS/MS. Online sample preparation is carried out on a TurboFlow Cyclone MAX column using turbulent flow chromatography. Sample preparation prior the analysis is minimized to a dilution and syringe filtration step leading to an instrumental analysis time of 33min. The limit of detection and the limit of quantification were 0.4ng and 0.6ng on column, respectively. Recovery of the main mono- and di-rhamnolipids from a fermentation sample was 102-104%. Additionally, the rhamnolipid biosynthetic precursors 3-hydroxy(alkanoyloxy)alkanoic acids (HAAs) are covered, albeit extraction is not quantitative (85-90%). The analysis of rhamnolipids from four different microbial species was in good agreement with previous reports. The presented method allows rapid and comprehensive analysis of rhamnolipids with minimal sample preparation directly from the fermentation broth. The application of complementary data-dependent MS/MS acquisition enables non-target screening of rhamnolipids.

  17. Rhamnolipid biosurfactant analysis using online turbulent flow chromatography-liquid chromatography-tandem mass spectrometry.

    PubMed

    Behrens, Beate; Helmer, Patrick O; Tiso, Till; Blank, Lars M; Hayen, Heiko

    2016-09-23

    Rhamnolipids are biosurfactants produced by a variety of bacterial species that present a promising alternative to surfactants from petrochemical or oleochemical origin. The success of the fermentation is evaluated by subsequent qualitative and quantitative analysis. However, the sample preparation for high numbers of samples is often laborious and inefficient. In this study an online sample preparation is developed for the qualitative and quantitative analysis of rhamnolipids by LC-MS/MS. Online sample preparation is carried out on a TurboFlow Cyclone MAX column using turbulent flow chromatography. Sample preparation prior the analysis is minimized to a dilution and syringe filtration step leading to an instrumental analysis time of 33min. The limit of detection and the limit of quantification were 0.4ng and 0.6ng on column, respectively. Recovery of the main mono- and di-rhamnolipids from a fermentation sample was 102-104%. Additionally, the rhamnolipid biosynthetic precursors 3-hydroxy(alkanoyloxy)alkanoic acids (HAAs) are covered, albeit extraction is not quantitative (85-90%). The analysis of rhamnolipids from four different microbial species was in good agreement with previous reports. The presented method allows rapid and comprehensive analysis of rhamnolipids with minimal sample preparation directly from the fermentation broth. The application of complementary data-dependent MS/MS acquisition enables non-target screening of rhamnolipids. PMID:27567141

  18. Determination of chloroacetanilide herbicide metabolites in water using high-performance liquid chromatography-diode array detection and high-performance liquid chromatography/mass spectrometry

    USGS Publications Warehouse

    Hostetler, K.A.; Thurman, E.M.

    2000-01-01

    Analytical methods using high-performance liquid chromatography-diode array detection (HPLC-DAD) and high-performance liquid chromatography/mass spectrometry (HPLC/MS) were developed for the analysis of the following chloroacetanilide herbicide metabolites in water: alachlor ethanesulfonic acid (ESA); alachlor oxanilic acid; acetochlor ESA; acetochlor oxanilic acid; metolachlor ESA; and metolachlor oxanilic acid. Good precision and accuracy were demonstrated for both the HPLC-DAD and HPLC/MS methods in reagent water, surface water, and ground water. The average HPLC-DAD recoveries of the chloroacetanilide herbicide metabolites from water samples spiked at 0.25, 0.5 and 2.0 ??g/l ranged from 84 to 112%, with relative standard deviations of 18% or less. The average HPLC/MS recoveries of the metabolites from water samples spiked at 0.05, 0.2 and 2.0 ??g/l ranged from 81 to 118%, with relative standard deviations of 20% or less. The limit of quantitation (LOQ) for all metabolites using the HPLC-DAD method was 0.20 ??g/l, whereas the LOQ using the HPLC/MS method was at 0.05 ??g/l. These metabolite-determination methods are valuable for acquiring information about water quality and the fate and transport of the parent chloroacetanilide herbicides in water. Copyright (C) 2000 Elsevier Science B.V.

  19. [Simultaneous determination of eight furocoumarines in cosmetics by high performance liquid chromatography and verification by liquid chromatography-tandem mass spectrometry].

    PubMed

    Ma, Huijuan; Ma, Qiang; Li, Wentao; Meng, Xianshuang; Li, Jingrui; Bai, Hua; Jiao, Yang; Zhang, Xiaoli

    2013-05-01

    A method using high performance liquid chromatography (HPLC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the simultaneous determination of eight furocoumarines (8-hydroxypsoralen, psoralen, isopsoralen, 8-methoxypsoralen, 5-methoxypsoralen, trioxsalen, imperatorin and isoimperatorin) in cosmetics. The cosmetic samples, including cream, lotion, shampoo, powder and lipstick, were supersonically extracted with appropriate solvents. The extract was centrifuged, and the supernatant was filtered through a membrane, and then separated on an Agilent Zorbax SB-Phenyl chromatographic column (250 mm x 4.6 mm, 5 microm) by gradient elution at a flow rate of 1.0 mL/min with methanol-acetonitrile-water as mobile phases. The column temperature was set at 30 degrees C. The wavelength of detection was 250 nm. The limits of quantification (LOQs) were 0.25 mg/kg for 8-hydroxypsoralen and 0.5 mg/kg for psoralen, isopsoralen, 8-methoxypsoralen, 5-methoxypsoralen, trioxsalen, imperatorin and isoimperatorin. The recoveries at three spiked levels were in the range of 85.0% - 105.8% with the relative standard deviations (RSDs) of 0.41% - 7.90%. The intra-day precision (n=6) was less than 1%, and the inter-day precision (n = 6) was less than 2% for the peak areas of the eight furocoumarines in a mixed standard solution. The method is accurate, simple, rapid and suitable for the determination of the eight furocoumarines in various cosmetic samples.

  20. [Simultaneous determination of eight furocoumarines in cosmetics by high performance liquid chromatography and verification by liquid chromatography-tandem mass spectrometry].

    PubMed

    Ma, Huijuan; Ma, Qiang; Li, Wentao; Meng, Xianshuang; Li, Jingrui; Bai, Hua; Jiao, Yang; Zhang, Xiaoli

    2013-05-01

    A method using high performance liquid chromatography (HPLC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the simultaneous determination of eight furocoumarines (8-hydroxypsoralen, psoralen, isopsoralen, 8-methoxypsoralen, 5-methoxypsoralen, trioxsalen, imperatorin and isoimperatorin) in cosmetics. The cosmetic samples, including cream, lotion, shampoo, powder and lipstick, were supersonically extracted with appropriate solvents. The extract was centrifuged, and the supernatant was filtered through a membrane, and then separated on an Agilent Zorbax SB-Phenyl chromatographic column (250 mm x 4.6 mm, 5 microm) by gradient elution at a flow rate of 1.0 mL/min with methanol-acetonitrile-water as mobile phases. The column temperature was set at 30 degrees C. The wavelength of detection was 250 nm. The limits of quantification (LOQs) were 0.25 mg/kg for 8-hydroxypsoralen and 0.5 mg/kg for psoralen, isopsoralen, 8-methoxypsoralen, 5-methoxypsoralen, trioxsalen, imperatorin and isoimperatorin. The recoveries at three spiked levels were in the range of 85.0% - 105.8% with the relative standard deviations (RSDs) of 0.41% - 7.90%. The intra-day precision (n=6) was less than 1%, and the inter-day precision (n = 6) was less than 2% for the peak areas of the eight furocoumarines in a mixed standard solution. The method is accurate, simple, rapid and suitable for the determination of the eight furocoumarines in various cosmetic samples. PMID:24010339

  1. Evaluation of the Kinetic Performance Differences between Hydrophilic-Interaction Liquid Chromatography and Reversed-Phase Liquid Chromatography under Conditions of Identical Packing Structure.

    PubMed

    Song, Huiying; Desmet, Gert; Cabooter, Deirdre

    2015-12-15

    A protocol using trifluoroacetic acid at a temperature of 60 °C is developed for the adequate removal of the stationary phase of reversed-phase liquid chromatography (RPLC) columns. This procedure allows for studying the same column first under RPLC and subsequently under hydrophilic-interaction liquid chromatography (HILIC) conditions to isolate intrinsic differences between mass transfer properties in HILIC and RPLC from differences in packing quality. The established procedure allows for a complete removal of the stationary phase (confirmed by retention studies and thermogravimetry analyses) while leaving the structure of the packing unaffected (witnessed by an unchanged external porosity and pressure drop). Accurate plate height analysis comparing compounds at the same zone retention factor indicates a significant difference in reduced c-term (typically 40-80% larger under HILIC conditions), despite the columns otherwise being identical. Correcting for the known contributions of longitudinal diffusion (b-term) and mass transfer (cm- and cs-term) to focus on band broadening originating from eddy dispersion, similar strong differences are observed (differences of some h = 0.3 up to 1.2). These findings show that the interior structure and retention mechanism of the particles have a very strong effect on the observed eddy dispersion, a factor typically ascribed to phenomena occurring outside the particles. This also implies that comparing the quality of packings of different particle types is virtually impossible without the availability of a sound model to correct for the intraparticle effect on the observed eddy dispersion.

  2. Determination of nitrofurans in animal feeds by liquid chromatography-UV photodiode array detection and liquid chromatography-ionspray tandem mass spectrometry.

    PubMed

    Barbosa, Jorge; Moura, Sara; Barbosa, Rita; Ramos, Fernando; da Silveira, Maria Irene Noronha

    2007-03-14

    Within the EU, the use of nitrofurans is prohibited in food production animals. For this reason detection of these compounds in feedingstuffs, at whatever limit, constitutes an offence under EU legislation. This detection generally involves the use of analytical methods with limits of quantification lowers than 1 mg kg(-1). These procedures are unsuitable for the detection and confirmation of trace amounts of nitrofurans in feedingstuffs due to contamination. It is well known that very low concentrations of these compounds can be the source of residues of nitrofuran metabolites in meat and other edible products obtained from animals consuming the contaminated feed. The present multi-compound method was capable of measuring very low concentrations of nitrofurantoin (NFT), nitrofurazone (NFZ), furazolidone (FZD) and furaltadone (FTD) in animal feed using nifuroxazide (NXZ) as internal standard. Following ethyl acetate extraction at mild alkaline conditions and purification on NH2 column, the nitrofurans are determined using liquid chromatography with photodiode-array detection (LC-DAD). It was observed a CCalpha ranged from 50 to 100 microg kg(-1). The liquid chromatography-tandem mass spectrometric (LC-MS/MS) procedure was used to confirm the identity of the suspected presence of any of the nitrofuran compounds. PMID:17386735

  3. Simultaneous determination of fluoroquinolones in foods of animal origin by a high performance liquid chromatography and a liquid chromatography tandem mass spectrometry with accelerated solvent extraction.

    PubMed

    Yu, Huan; Tao, Yanfei; Chen, Dongmei; Pan, Yuanhu; Liu, Zhenli; Wang, Yulian; Huang, Lingli; Dai, Menghong; Peng, Dapeng; Wang, Xu; Yuan, Zonghui

    2012-02-15

    A confirmatory and quantitative method based on a high performance liquid chromatography UV detector (HPLC-UV) and a liquid chromatography tandem mass spectrometry (LC-MS/MS) with an extraction procedure of accelerated solvent extraction (ASE) has been developed for simultaneous determination of 15 kinds of fluoroquinolones in various animal origin food samples. The sample preparation procedures consist of an extraction step with acetonitrile and a cleaning-up step with Oasis HLB cartridge. Parameters for extraction pressure and temperature, cycle of ASE, clean-up, and analysis procedure have been optimized systematically. The recoveries of FQNs spiked in the tissues as the muscle, liver, kidney of swine, bovine, chicken and fish at a concentration range of 10-800μg/kg were found between 70.6% and 111.1% with relative standard deviations (RSD) less than 15% in HPLC. The LOD and LOQ of the HPLC for the 15 FQNs were 3μg/kg and 10μg/kg, respectively, and those of the LC-MS/MS were 0.3 and 1μg/kg, respectively. These rapid and reliable methods can be used to efficiently separate, characterize and quantify the residues of 15 FQNs (Marbofloxacin, Enoxacin, Fleroxacin, Ofloxacin, Pefloxacin, Lomefloxacin, Danofloxacin, Enrofloxacin, Orbifloxacin, Cinoxacin, Gatifloxacin, Sarafloxacin, Difloxacin, Nalidixic Acid, Flumequine) in food of animal origin.

  4. Separation and characterization of bufadienolides in toad skin using two-dimensional normal-phase liquid chromatography×reversed-phase liquid chromatography coupled with mass spectrometry.

    PubMed

    Zhang, Yun; Jin, Hongli; Li, Xiaolong; Zhao, Jianqiang; Guo, Xiujie; Wang, Jixia; Guo, Zhimou; Zhang, Xiuli; Tao, Yanduo; Liu, Yanfang; Chen, Deliang; Liang, Xinmiao

    2016-07-15

    Bufadienolides possess various bioactivities especially antitumor. Due to the high structural diversity, the separation of bufadienolides often suffers from coelution problem on conventional RP columns. In this work, an off-line two-dimensional normal-phase liquid chromatography×reversed-phase liquid chromatography (2D-NPLC×RPLC) method was developed to separate and characterize bufadienolides in toad skin. Several RP and NP columns were evaluated with five reference bufadienlides. The XUnion C18 and XAmide columns exhibited superior chromatographic performances for bufadienlide separation, and were selected in RPLC and NPLC, respectively. RPLC was used in the second-dimension for the good compatibility with MS, while NPLC was adopted in the first-dimension. The orthogonality of the 2D-NPLC×RPLC system was investigated by the geometric approach using fifteen bufadienolide mixtures. The result was 49.6%, demonstrating reasonable orthogonality of this 2D-LC system. By combining the 2D-LC system with MS, 64 bufadienlides including 33 minor ones and 11 pairs of isomers in toad skin were identified. This off-line 2D-NPLC×RPLC allowed to solve the coelution problem of bufadienlides in one-dimension RPLC, and thus facilitated the identification significantly.

  5. Evaluation of the Kinetic Performance Differences between Hydrophilic-Interaction Liquid Chromatography and Reversed-Phase Liquid Chromatography under Conditions of Identical Packing Structure.

    PubMed

    Song, Huiying; Desmet, Gert; Cabooter, Deirdre

    2015-12-15

    A protocol using trifluoroacetic acid at a temperature of 60 °C is developed for the adequate removal of the stationary phase of reversed-phase liquid chromatography (RPLC) columns. This procedure allows for studying the same column first under RPLC and subsequently under hydrophilic-interaction liquid chromatography (HILIC) conditions to isolate intrinsic differences between mass transfer properties in HILIC and RPLC from differences in packing quality. The established procedure allows for a complete removal of the stationary phase (confirmed by retention studies and thermogravimetry analyses) while leaving the structure of the packing unaffected (witnessed by an unchanged external porosity and pressure drop). Accurate plate height analysis comparing compounds at the same zone retention factor indicates a significant difference in reduced c-term (typically 40-80% larger under HILIC conditions), despite the columns otherwise being identical. Correcting for the known contributions of longitudinal diffusion (b-term) and mass transfer (cm- and cs-term) to focus on band broadening originating from eddy dispersion, similar strong differences are observed (differences of some h = 0.3 up to 1.2). These findings show that the interior structure and retention mechanism of the particles have a very strong effect on the observed eddy dispersion, a factor typically ascribed to phenomena occurring outside the particles. This also implies that comparing the quality of packings of different particle types is virtually impossible without the availability of a sound model to correct for the intraparticle effect on the observed eddy dispersion. PMID:26595107

  6. Chemical fingerprint of Ganmaoling granule by double-wavelength ultra high performance liquid chromatography and ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry.

    PubMed

    Lou, Qiong; Ye, Xiaolan; Zhou, Yingyi; Li, Hua; Song, Fenyun

    2015-06-01

    A method incorporating double-wavelength ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry was developed for the investigation of the chemical fingerprint of Ganmaoling granule. The chromatographic separations were performed on an ACQUITY UPLC HSS C18 column (2.1 × 50 mm, 1.8 μm) at 30°C using gradient elution with water/formic acid (1%) and acetonitrile at a flow rate of 0.4 mL/min. A total of 11 chemical constituents of Ganmaoling granule were identified from their molecular weight, UV spectra, tandem mass spectrometry data, and retention behavior by comparing the results with those of the reference standards or literature. And 25 peaks were selected as the common peaks for fingerprint analysis to evaluate the similarities among 25 batches of Ganmaoling granule. The results of principal component analysis and orthogonal projection to latent structures discriminant analysis showed that the important chemical markers that could distinguish the different batches were revealed as 4,5-di-O-caffeoylquinic acid, 3,5-di-O-caffeoylquinic acid, and 4-O-caffeoylquinic acid. This is the first report of the ultra high performance liquid chromatography chemical fingerprint and component identification of Ganmaoling granule, which could lay a foundation for further studies of Ganmaoling granule.

  7. Online coupling of hydrophilic interaction/strong cation exchange/reversed-phase liquid chromatography with porous graphitic carbon liquid chromatography for simultaneous proteomics and N-glycomics analysis.

    PubMed

    Zhao, Yun; Law, Henry C H; Zhang, Zaijun; Lam, Herman C; Quan, Quan; Li, Guohui; Chu, Ivan K

    2015-10-01

    In this study we developed a fully automated three-dimensional (3D) liquid chromatography methodology-comprising hydrophilic interaction separation as the first dimension, strong cation exchange fractionation as the second dimension, and low-pH reversed-phase (RP) separation as the third dimension-in conjunction downstream with additional complementary porous graphitic carbon separation, to capture non-retained hydrophilic analytes, for both shotgun proteomics and N-glycomics analyses. The performance of the 3D system alone was benchmarked through the analysis of the total lysate of Saccharomyces cerevisiae, leading to improved hydrophilic peptide coverage, from which we identified 19% and 24% more proteins and peptides, respectively, relative to those identified from a two-dimensional hydrophilic interaction liquid chromatography and low-pH RP chromatography (HILIC-RP) system over the same mass spectrometric acquisition time; consequently, the 3D platform also provided enhanced proteome and protein coverage. When we applied the integrated technology to analyses of the total lysate of primary cerebellar granule neurons, we characterized a total of 2201 proteins and 16,937 unique peptides for this primary cell line, providing one of its most comprehensive datasets. Our new integrated technology also exhibited excellent performance in the first N-glycomics analysis of cynomolgus monkey plasma; we successfully identified 122 proposed N-glycans and 135 N-glycosylation sites from 122 N-glycoproteins, and confirmed the presence of 38 N-glycolylneuraminic acid-containing N-glycans, a rare occurrence in human plasma, through tandem mass spectrometry for the first time.

  8. Quantitative liquid chromatography/tandem mass spectrometry determination of chloramphenicol residues in food using sub-2 microm particulate high-performance liquid chromatography columns for sensitivity and speed.

    PubMed

    Kaufmann, Anton; Butcher, Patrick

    2005-01-01

    The use of chloramphenicol (CAP)--a highly effective broad-spectrum antibiotic used in animal husbandry--is banned in many countries. Therefore, a very low minimum required performance limit (MRPL) of 0.3 microg/kg CAP in meat for human consumption has been defined. Analytical methods capable of quantifying and confirming such low residue levels require sophisticated instrumentation. Preferably sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) or gas chromatography/mass spectrometry (GC/MS) methods have been used. This paper suggests the use of sub-2 microm particulate high-performance liquid chromatography (HPLC) columns to gain additional sensitivity and improve resolution as well as speed. Depending on the operating conditions, higher chromatographic resolution and speed can be obtained at the price of a significantly increased operating pressure, requiring dedicated LC equipment. A 3-4-fold overall improvement of the signal-to-noise ratio for CAP was obtained compared to more classical 5 microm particulate HPLC columns. The proposed analytical methodology includes an enzymatic digestion, which liberates glucuronide-bound CAP from kidney tissue. The extracts obtained after an Extrelut clean-up are sufficiently pure to permit routine injection of biological samples into the sub-2 microm particulate HPLC column, without observing rapid deterioration of peak shape or column clogging problems. The time for one chromatographic run was 4.2 min. The described method was validated for two particularly difficult matrices (kidney and honey). Decision limits (CC alpha) were 0.007 microg/kg (honey) und 0.011 microg/kg (kidney), which are significantly below the current MRPL. PMID:16299695

  9. Development, validation and determination of multiclass pesticide residues in cocoa beans using gas chromatography and liquid chromatography tandem mass spectrometry.

    PubMed

    Zainudin, Badrul Hisyam; Salleh, Salsazali; Mohamed, Rahmat; Yap, Ken Choy; Muhamad, Halimah

    2015-04-01

    An efficient and rapid method for the analysis of pesticide residues in cocoa beans using gas and liquid chromatography-tandem mass spectrometry was developed, validated and applied to imported and domestic cocoa beans samples collected over 2 years from smallholders and Malaysian ports. The method was based on solvent extraction method and covers 26 pesticides (insecticides, fungicides, and herbicides) of different chemical classes. The recoveries for all pesticides at 10 and 50 μg/kg were in the range of 70-120% with relative standard deviations of less than 20%. Good selectivity and sensitivity were obtained with method limit of quantification of 10 μg/kg. The expanded uncertainty measurements were in the range of 4-25%. Finally, the proposed method was successfully applied for the routine analysis of pesticide residues in cocoa beans via a monitoring study where 10% of them was found positive for chlorpyrifos, ametryn and metalaxyl. PMID:25442595

  10. [Trigonelline in coffee. I. Comparison of thin layer chromatography with high-performance liquid chromatography. Simultaneous determination of caffeine].

    PubMed

    Stennert, A; Maier, H G

    1993-05-01

    Determination of trigonelline in several green and roasted coffees by thin-layer (TLC) and high-performance liquid chromatography (HPLC) were compared. Using TLC, two methods of detection were also compared. In addition, caffeine could be determined using HPLC. The determinations were each made with several variations of extraction and clean-up. Recoveries, variation coefficients and detection limits are listed. The most suitable method was HPLC in connection with hot water extraction. Only water is required as the mobile phase. The values for precision are in most cases better than (trigonelline) or similar to (caffeine) those reported in the literature. The determination of trigonelline by TLC, followed by extraction and photometry, is possible with a similar precision, but the simultaneous determination of caffeine was not tested. PMID:8511975

  11. Development, validation and determination of multiclass pesticide residues in cocoa beans using gas chromatography and liquid chromatography tandem mass spectrometry.

    PubMed

    Zainudin, Badrul Hisyam; Salleh, Salsazali; Mohamed, Rahmat; Yap, Ken Choy; Muhamad, Halimah

    2015-04-01

    An efficient and rapid method for the analysis of pesticide residues in cocoa beans using gas and liquid chromatography-tandem mass spectrometry was developed, validated and applied to imported and domestic cocoa beans samples collected over 2 years from smallholders and Malaysian ports. The method was based on solvent extraction method and covers 26 pesticides (insecticides, fungicides, and herbicides) of different chemical classes. The recoveries for all pesticides at 10 and 50 μg/kg were in the range of 70-120% with relative standard deviations of less than 20%. Good selectivity and sensitivity were obtained with method limit of quantification of 10 μg/kg. The expanded uncertainty measurements were in the range of 4-25%. Finally, the proposed method was successfully applied for the routine analysis of pesticide residues in cocoa beans via a monitoring study where 10% of them was found positive for chlorpyrifos, ametryn and metalaxyl.

  12. Simultaneous achiral-chiral analysis of pharmaceutical compounds using two-dimensional reversed phase liquid chromatography-supercritical fluid chromatography.

    PubMed

    Venkatramani, C J; Al-Sayah, Mohammad; Li, Guannan; Goel, Meenakshi; Girotti, James; Zang, Lisa; Wigman, Larry; Yehl, Peter; Chetwyn, Nik

    2016-02-01

    A new interface was designed to enable the coupling of reversed phase liquid chromatography (RPLC) and supercritical fluid chromatography (SFC). This online two-dimensional chromatographic system utilizing RPLC in the first dimension and SFC in the second was developed to achieve simultaneous achiral and chiral analysis of pharmaceutical compounds. The interface consists of an eight-port, dual-position switching valve with small volume C-18 trapping columns. The peaks of interest eluting from the first RPLC dimension column were effectively focused as sharp concentration pulses on small volume C-18 trapping column/s and then injected onto the second dimension SFC column. The first dimension RPLC separation provides the achiral purity result, and the second dimension SFC separation provides the chiral purity result (enantiomeric excess). The results are quantitative enabling simultaneous achiral, chiral analysis of compounds. The interface design and proof of concept demonstration are presented. Additionally, comparative studies to conventional SFC and case studies of the applications of 2D LC-SFC in pharmaceutical analysis is presented.

  13. Phytochemical Profile of Erythrina variegata by Using High-Performance Liquid Chromatography and Gas Chromatography-Mass Spectroscopy Analyses.

    PubMed

    Muthukrishnan, Suriyavathana; Palanisamy, Subha; Subramanian, Senthilkumar; Selvaraj, Sumathi; Mari, Kavitha Rani; Kuppulingam, Ramalingam

    2016-08-01

    Natural products derived from plant sources have been utilized to treat patients with numerous diseases. The phytochemical constituents present in ethanolic leaf extract of Erythrina variegata (ELEV) were identified by using high-performance liquid chromatography (HPLC) and gas chromatography-mass spectroscopy (GC-MS) analyses. Shade dried leaves were powdered and extracted with ethanol for analyses through HPLC to identify selected flavonoids and through GC-MS to identify other molecules. The HPLC analysis of ELEV showed the presence of gallic and caffeic acids as the major components at concentrations of 2.0 ppm and 0.1 ppm, respectively, as well as other components. GC-MS analysis revealed the presence of 3-eicosyne; 3,7,11,15-tetramethyl-2-hexadecen-1-ol; butanoic acid, 3-methyl-3,7-dimethyl-6-octenyl ester; phytol; 1,2-benzenedicarboxylic acid, diundecyl ester; 1-octanol, 2-butyl-; squalene; and 2H-pyran, 2-(7-heptadecynyloxy) tetrahydro-derivative. Because pharmacopuncture is a new evolving natural mode that uses herbal extracts for treating patients with various ailments with minimum pain and maximum effect, the results of this study are particularly important and show that ELEV possesses a wide range of phytochemical constituents, as indicated above, as effective active principle molecules that can be used individually or in combination to treat patients with various diseases. PMID:27555226

  14. Differentiation of coloured inks of inkjet printer cartridges by thin layer chromatography and high performance liquid chromatography.

    PubMed

    Poon, N L; Ho, S S H; Li, C K

    2005-01-01

    Document examiners are frequently asked to determine whether or not a colour printout has originated from a particular inkjet printer. The printer can rarely be identified unless some unique defects or irregularities of the printer are present on the printout. However, it is possible to decipher the make and/or model of the printer by comparing the ink-profile of the questioned printout with that of a seized inkjet printer cartridge or from one in a database. This paper presents an overview of a systematic approach to characterising and discriminating the inks of different inkjet printer cartridges using thin layer chromatography (TLC) and high pressure liquid chromatography (HPLC) with multi-wavelength ultra-violet/visible (UV/Vis) detection. Ink samples from 23 different inkjet printer cartridges (including originals and substitutes) of different brands and colour printouts, printed by known printers were examined with newly developed chromatographic methods. Subsequently, a database of the ink-profiles was generated. The methods provide a useful tool for discriminating coloured inks in inkjet printer cartridges of different brands.

  15. Post Column Derivatization Using Reaction Flow High Performance Liquid Chromatography Columns.

    PubMed

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

    2016-04-26

    A protocol for the use of reaction flow high performance liquid chromatography columns for methods employing post column derivatization (PCD) is presented. A major difficulty in adapting PCD to modern HPLC systems and columns is the need for large volume reaction coils that enable reagent mixing and then the derivatization reaction to take place. This large post column dead volume leads to band broadening, which results in a loss of observed separation efficiency and indeed detection in sensitivity. In reaction flow post column derivatization (RF-PCD) the derivatization reagent(s) are pumped against the flow of mobile phase into either one or two of the outer ports of the reaction flow column where it is mixed with column effluent inside a frit housed within the column end fitting. This technique allows for more efficient mixing of the column effluent and derivatization reagent(s) meaning that the volume of the reaction loops can be minimized or even eliminated altogether. It has been found that RF-PCD methods perform better than conventional PCD methods in terms of observed separation efficiency and signal to noise ratio. A further advantage of RF-PCD techniques is the ability to monitor effluent coming from the central port in its underivatized state. RF-PCD has currently been trialed on a relatively small range of post column reactions, however, there is currently no reason to suggest that RF-PCD could not be adapted to any existing one or two component (as long as both reagents are added at the same time) post column derivatization reaction.

  16. Liquid chromatography/microspray mass spectrometry for bacterial investigations.

    PubMed

    Krishnamurthy, T; Davis, M T; Stahl, D C; Lee, T D

    1999-01-01

    Cellular proteins (biomarkers) specific to any individual microorganism, determined by the direct mass spectral analysis of the corresponding intact cellular suspension, can be applied for the rapid and specific identification of the organisms present in unknown samples. The components of the bacterial suspensions, after a rapid separation over a C18 reversed-phase microcapillary column, were directly subjected to on-line electrospray ionization followed by analysis using an ion trap tandem mass spectrometer. This approach is equally effective for gram-positive as well as gram-negative bacteria but has a distinct advantage over our earlier reported method involving matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). During electrospray ionitation mass spectrometry (ESI-MS), liquid samples can be directly analyzed and there is the potential for developing tandem mass spectral methods for more specific identification of the individual organisms present in crude bacterial mixtures. The total analysis time leading to unambiguous bacterial identification in samples was less than 10 minutes and the results were quite reproducible. Miniaturization of the instrumentation along with total automation of this simple process could have immense impact on field operations. Routine, rapid, cost-effective field monitoring of environmental samples, agricultural products, samples from food processing, industrial sites and health institutions for suspected bacterial contamination could be a reality in the near future. Potential utility in biological, medical, bioprocessing, pharmaceutical, and other industrial research is also enormous.

  17. Circulating ultrasound-assisted extraction, countercurrent chromatography, and liquid chromatography for the simultaneous extraction, isolation, and analysis of the constituents of Uncaria tomentosa.

    PubMed

    Zhang, Yuchi; Liu, Chunming; Qi, Yanjuan; Li, Sainan; Pan, Yan; Li, Yuchun

    2015-04-01

    A hyphenated automated technique for the online extraction, isolation, analysis, and identification of natural organic compounds was established. Circulating ultrasound-assisted extraction (CUAE) was coupled with countercurrent chromatography (CCC), high performance liquid chromatography (HPLC), and a diode array detector (DAD). This approach was applied to the fractionation and purification of alkaloids from Uncaria tomentosa. A biphasic solvent system of chloroform-methanol-water (6:4:5, v:v:v) was used for the CUAE and CCC separation of compounds from 500 g of U. tomentosa. Two CUAE/CCC/HPLC/DAD modes were established. Either the upper aqueous phase or the lower organic phase of the solvent system could be used as the extraction solvent. The target compounds were extracted by CUAE, and the extract was pumped into a sample loop before being directly injected into the CCC column, or pre-purified using a flash chromatography column before injection. The target compounds were eluted using either the organic or aqueous phase of the solvent system and the fractions were monitored using a UV detector. The target fractions were collected by a sample loop via a six-port valve, and analyzed by HPLC/DAD for purity and structural identification. This system isolated of 8.2mg, 7.4 mg, and 12.9 mg of rhynchophylline, corynoxine, and corynoxine B with HPLC purities of 96.15%, 95.34%, and 95.49%, respectively via the first mode; and isolated 26.6 mg, 24.6 mg, and 45.3mg of rhynchophylline, corynoxine, and corynoxine B with a HPLC purities of 98.22%, 97.18%, and 97.93% via the second mode.

  18. Preparative isolation of novel antioxidant flavonoids of alfalfa by stop-and-go counter-current chromatography and following on-line liquid chromatography desalination.

    PubMed

    Liang, Junling; Yang, Zhi; Cao, Xiaoji; Wu, Bing; Wu, Shihua

    2011-09-01

    In this work, we have established a new stop-and-go two-dimensional chromatography coupling of counter-current chromatography and liquid chromatography (2D CCC × LC) for the preparative separation of two novel antioxidant flavonoids from the extract of alfalfa (Medicago sativa L.). The CCC column has been used as the first dimension to purify the target flavonoids using a solvent system of isopropanol and 20% sodium chloride aqueous solution (1:1, v/v) with the stop-and-go flow technique, and the LC column packed with macroporous resin has been employed as the second dimension for on-line absorption, desalination and desorption of the targeting effluents purified from the first CCC dimension. As a result, two novel flavonoids, 6,8-dihydroxy-flavone-7-O-β-D-glucuronide (15.3 mg) and 6-methoxy-8-hydroxy-flavone-7-O-β-D-glucuronide (13.7 mg), have been isolated from 126.8 mg of crude sample pre-enriched by macroporous resin column. Their structures have been identified by electrospray ionization mass spectrometry (ESI-MS), electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) and one- and two-dimensional nuclear magnetic resonance spectra (1D and 2D NMR). Further antioxidant assays showed that the first component possess a strong antioxidant activity. All the results demonstrated that the stop-and-go 2D CCC × LC method is very efficient for the separation of flavonoids of alfalfa and it can also be applied to isolate other comprehensive multi-component natural products.

  19. Preparative isolation of novel antioxidant flavonoids of alfalfa by stop-and-go counter-current chromatography and following on-line liquid chromatography desalination.

    PubMed

    Liang, Junling; Yang, Zhi; Cao, Xiaoji; Wu, Bing; Wu, Shihua

    2011-09-01

    In this work, we have established a new stop-and-go two-dimensional chromatography coupling of counter-current chromatography and liquid chromatography (2D CCC × LC) for the preparative separation of two novel antioxidant flavonoids from the extract of alfalfa (Medicago sativa L.). The CCC column has been used as the first dimension to purify the target flavonoids using a solvent system of isopropanol and 20% sodium chloride aqueous solution (1:1, v/v) with the stop-and-go flow technique, and the LC column packed with macroporous resin has been employed as the second dimension for on-line absorption, desalination and desorption of the targeting effluents purified from the first CCC dimension. As a result, two novel flavonoids, 6,8-dihydroxy-flavone-7-O-β-D-glucuronide (15.3 mg) and 6-methoxy-8-hydroxy-flavone-7-O-β-D-glucuronide (13.7 mg), have been isolated from 126.8 mg of crude sample pre-enriched by macroporous resin column. Their structures have been identified by electrospray ionization mass spectrometry (ESI-MS), electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) and one- and two-dimensional nuclear magnetic resonance spectra (1D and 2D NMR). Further antioxidant assays showed that the first component possess a strong antioxidant activity. All the results demonstrated that the stop-and-go 2D CCC × LC method is very efficient for the separation of flavonoids of alfalfa and it can also be applied to isolate other comprehensive multi-component natural products. PMID:21092976

  20. Experimental study of liquid level gauge for liquid hydrogen using Helmholtz resonance technique

    NASA Astrophysics Data System (ADS)

    Nakano, Akihiro; Nishizu, Takahisa

    2016-07-01

    The Helmholtz resonance technique was applied to a liquid level gauge for liquid hydrogen to confirm the applicability of the technique in the cryogenic industrial field. A specially designed liquid level gauge that has a Helmholtz resonator with a small loudspeaker was installed in a glass cryostat. A swept frequency signal was supplied to the loudspeaker, and the acoustic response was detected by measuring the electrical impedance of the loudspeaker's voice coil. The penetration depth obtained from the Helmholtz resonance frequency was compared with the true value, which was read from a scale. In principle, the Helmholtz resonance technique is available for use with liquid hydrogen, however there are certain problems as regards practical applications. The applicability of the Helmholtz resonance technique to liquid hydrogen is discussed in this study.

  1. Fully automated multifunctional ultrahigh pressure liquid chromatography system for advanced proteome analyses

    SciTech Connect

    Lee, Jung Hwa; Hyung, Seok-Won; Mun, Dong-Gi; Jung, Hee-Jung; Kim, Hokeun; Lee, Hangyeore; Kim, Su-Jin; Park, Kyong Soo; Moore, Ronald J.; Smith, Richard D.; Lee, Sang-Won

    2012-08-03

    A multi-functional liquid chromatography system that performs 1-dimensional, 2-dimensional (strong cation exchange/reverse phase liquid chromatography, or SCX/RPLC) separations, and online phosphopeptides enrichment using a single binary nano-flow pump has been developed. With a simple operation of a function selection valve, which is equipped with a SCX column and a TiO2 (titanium dioxide) column, a fully automated selection of three different experiment modes was achieved. Because the current system uses essentially the same solvent flow paths, the same trap column, and the same separation column for reverse-phase separation of 1D, 2D, and online phosphopeptides enrichment experiments, the elution time information obtained from these experiments is in excellent agreement, which facilitates correlating peptide information from different experiments.

  2. Alternative solvents for improving the greenness of normal phase liquid chromatography of lipid classes.

    PubMed

    Prache, Nolwenn; Abreu, Sonia; Sassiat, Patrick; Thiébaut, Didier; Chaminade, Pierre

    2016-09-16

    An evaluation of solvents alternative to n-heptane (d-limonene and hexamethyldisiloxane) and chloroform (cyclopentyl methyl ether, 2-methyltetrahydrofuran and isopentyl acetate) was developed for lipid classes separation of non-polar cholesteryl ester to highly polar phospholipids by high-performance liquid chromatography on bare silica stationary phase and evaporative light-scattering detection. Screening of alternative solvents was used to estimate their compatibility with liquid chromatography and evaporative light-scattering detection and to evaluate their chromatographic selectivity. This work shows that n-heptane can be advantageously replaced by hexamethyldisiloxane. An increase of non-polar lipids retention is observed with hexamethyldisiloxane as weak solvent. Chloroform, which is largely used for lipid analysis, might be replaced efficaciously by cyclopentyl methyl ether, 2-methyltetrahydrofuran or isopentyl acetate. Aside from offering a different selectivity, the gradients composed by one or both alternative solvents gave efficient and comparable or even better separations than those obtained with conventional solvents. PMID:27554026

  3. Analysis of antimycin A by reversed-phase liquid chromatography/nuclear magnetic-resonance spectrometry

    USGS Publications Warehouse

    Ha, Steven T.K.; Wilkins, Charles L.; Abidi, Sharon L.

    1989-01-01

    A mixture of closely related streptomyces fermentation products, antimycin A, Is separated, and the components are identified by using reversed-phase high-performance liquid chromatography with directly linked 400-MHz proton nuclear magnetic resonance detection. Analyses of mixtures of three amino acids, alanine, glycine, and valine, are used to determine optimal measurement conditions. Sensitivity increases of as much as a factor of 3 are achieved, at the expense of some loss in chromatographic resolution, by use of an 80-μL NMR cell, Instead of a smaller 14-μL cell. Analysis of the antimycin A mixture, using the optimal analytical high performance liquid chromatography/nuclear magnetic resonance conditions, reveals it to consist of at least 10 closely related components.

  4. Two-dimensional liquid chromatography system for online top-down mass spectrometry

    SciTech Connect

    Tian, Zhixin; Zhao, Rui; Tolic, Nikola; Moore, Ronald J.; Stenoien, David L.; Robinson, Errol W.; Smith, Richard D.; Pasa-Tolic, Ljiljana

    2010-10-01

    An online metal-free weak cation exchange-hydrophilic interaction liquid chromatography/reversed phase liquid chromatography (WCX-HILIC/RPLC) system has been developed for sensitive high-throughput top-down mass spectrometry. Analyzing posttranslational modifications (PTMs) of core histones, with focus on histone H4, tested the system. Using ~24 μg of core histones (H4, H2B, H2A and H3) purified from human fibroblasts, 41 H4 isoforms were identified, with the type and locations of PTMs unambiguously mapped for 20 of these variants. Compared to corresponding offline studies reported previously, online WCXHILIC/ RPLC platform offers significant improvement in sensitivity, with several orders of magnitude reduction in sample requirements and reduction in the overall analysis time. To the best of our knowledge, this study represents the first online two-dimensional (2D) LC-MS/MS characterization of core histone mixture at the intact protein level.

  5. Gas-liquid chromatography in routine processing of blood cultures for detecting anaerobic bacteraemia.

    PubMed Central

    Reig, M; Molina, D; Loza, E; Ledesma, M A; Meseguer, M A

    1981-01-01

    Gas-liquid chromatography was performed on 233 positive blood cultures and findings were compared with culture results. Obligate anaerobic bacteria were recovered from 78 out of 79 blood cultures containing butyric or iso-valeric acids, or both; from 28 out of 69 blood cultures containing succinic acid; and from only one out of 41 blood cultures containing succinic but not butyric or iso-valeric acid. Good correlations (88%) were found for the recovery of anaerobic bacteria and the detection of butyric and/or iso-valeric acids. Detecting volatile fatty acids by gas-liquid chromatography performed on blood cultures at the first signs of growth can therefore provide an early and reliable indication of the presence of anaerobic bacteria. PMID:7014645

  6. Homochiral metal-organic framework used as a stationary phase for high-performance liquid chromatography.

    PubMed

    Kong, Jiao; Zhang, Mei; Duan, Ai-Hong; Zhang, Jun-Hui; Yang, Rui; Yuan, Li-Ming

    2015-02-01

    Metal-organic frameworks are promising porous materials. Chiral metal-organic frameworks have attracted considerable attention in controlling enantioselectivity. In this study, a homochiral metal-organic framework [Co(2) (D-cam)(2) (TMDPy)] (D-cam = D-camphorates, TMDPy = 4,4'-trimethylenedipyridine) with a non-interpenetrating primitive cubic net has been used as a chiral stationary phase in high-performance liquid chromatography. It has allowed the successful separation of six positional isomers and six chiral compounds. The good selectivity and baseline separation, or at least 60% valley separation, confirmed its excellent molecular recognition characteristics. The relative standard deviations for the retention time of run-to-run and column-to-column were less than 1.8 and 3.1%, respectively. These results demonstrate that [Co(2) (D-cam)(2) (TMDPy)] may represent a promising chiral stationary phase for use in high-performance liquid chromatography.

  7. Analyses of acute kidney injury biomarkers by ultra-high performance liquid chromatography with mass spectrometry.

    PubMed

    Al Za'abi, Mohammed; Ali, Badreldin H; ALOthman, Zeid A; Ali, Imran

    2016-01-01

    The newly developed acute kidney injury biomarkers are very important for the early and timely detection of kidney diseases. This review contains details of the analyses of several acute kidney injury biomarkers using ultra-high performance liquid chromatography-mass spectrometry in urine and plasma samples. In this review we attempt to discuss some aspects of the types of the biomarkers, patents, sample preparation, and the analyses. Besides, efforts were also made to discuss the possible uses of superficially porous (core-shell) columns in traditional and inexpensive high-performance liquid chromatography instruments. Additionally, the challenges and the future prospects are also highlighted. The present review will be useful for the academicians, scientists, and clinicians for the early detection of acute kidney injury biomarkers.

  8. Solvent systems for countercurrent chromatography: an aqueous two phase liquid system based on a room temperature ionic liquid.

    PubMed

    Ruiz-Angel, Maria Jose; Pino, Veronica; Carda-Broch, Samuel; Berthod, Alain

    2007-06-01

    A new aqueous two phase liquid system (ATPS) based on the ionic liquid 1-butyl-3-methyl imidazolium chloride (BMIM Cl), potassium dibasic phosphate (K(2)HPO(4)) and water was recently proposed in the literature. The full phase diagram of this ATPS was prepared and some tie lines were fully determined. It was compared to classical ATPSs based on polyethylene glycol with an average molecular mass of 1000 (PEG 1000) and 10,000 (PEG 10000) and K(2)HPO(4). Two countercurrent chromatography (CCC) columns, a hydrostatic Sanki and a J type hydrodynamic CCC columns were used to test the liquid phase retention of these ATPSs in all possible configurations. It was found that the BMIM Cl ATPS liquid phases were much easier to retain in the two CCC columns than the PEG 1000 ATPS phases. Using protein and alcohol solutes, it was established that the BMIM Cl ATPS has a polarity completely different from that of the PEG 1000 ATPS. For example, ovalbumin partitions equally between the two phases of the PEG 1000 ATPS (K(D)=1.4) when it is completely located in the BMIM Cl upper phase of the ionic liquid ATPS (K(D)=180). The discrimination factor of the ionic liquid system and its intrinsic hydrophobicity were respectively found three times higher and ten times lower than the respective values of the PEG 1000 ATPS. PMID:17166506

  9. [Determination of N-nitrosodimethylamine in beer by frozen zone melting liquid-liquid extraction/gas chromatography].

    PubMed

    Peng, Qiaorong; Tang, Tao; Yu, Shuxin; Sun, Yuanshe; Lei, Wu; Wang, Fengyun; Zhang, Weibing; Li, Tong

    2014-04-01

    A simple and effective sample enrichment method of frozen zone melting liquid-liquid extraction was optimized and validated for the analysis of trace N-nitrosodimethylamine (NDMA) in beer samples. The method was based on high pressure liquid-liquid extraction with a low temperature frozen step. The 90 mL beer was placed in a container with 10 mL dichloromethane. After agitation, the sample was kept in a freezer for 16 h at -19 degrees C. The organic extract was analyzed by gas chromatography with a flame ionization detector (GC-FID). The accuracy, precision, detection and quantification limits and linearity of the method were evaluated. The results showed that the calibration curve of NDMA was linear in the range of 5-200 mg/L with a good correlation coefficient (r2) of 0.999 6. The recoveries at the spiked levels of 5, 10 and 20 mg/L were 84.94%, 83.24%, 85.14% with the relative standard deviations (n = 7) of 3.06%, 3.19%, 2.63%, respectively. The ordinary extraction method of N-nitrosodimethylamine in beer includes the four steps of low-temperature distillation, liquid-liquid extraction, rotary evaporation and nitrogen blowing concentration. With the extremely low volume of solvent used, the proposed extraction method proved to be easy and simple, and adequate for high-throughput analysis at low cost. PMID:25069335

  10. [Determination of N-nitrosodimethylamine in beer by frozen zone melting liquid-liquid extraction/gas chromatography].

    PubMed

    Peng, Qiaorong; Tang, Tao; Yu, Shuxin; Sun, Yuanshe; Lei, Wu; Wang, Fengyun; Zhang, Weibing; Li, Tong

    2014-04-01

    A simple and effective sample enrichment method of frozen zone melting liquid-liquid extraction was optimized and validated for the analysis of trace N-nitrosodimethylamine (NDMA) in beer samples. The method was based on high pressure liquid-liquid extraction with a low temperature frozen step. The 90 mL beer was placed in a container with 10 mL dichloromethane. After agitation, the sample was kept in a freezer for 16 h at -19 degrees C. The organic extract was analyzed by gas chromatography with a flame ionization detector (GC-FID). The accuracy, precision, detection and quantification limits and linearity of the method were evaluated. The results showed that the calibration curve of NDMA was linear in the range of 5-200 mg/L with a good correlation coefficient (r2) of 0.999 6. The recoveries at the spiked levels of 5, 10 and 20 mg/L were 84.94%, 83.24%, 85.14% with the relative standard deviations (n = 7) of 3.06%, 3.19%, 2.63%, respectively. The ordinary extraction method of N-nitrosodimethylamine in beer includes the four steps of low-temperature distillation, liquid-liquid extraction, rotary evaporation and nitrogen blowing concentration. With the extremely low volume of solvent used, the proposed extraction method proved to be easy and simple, and adequate for high-throughput analysis at low cost.

  11. Determination of diflubenzuron and chlorbenzuron in fruits by combining acetonitrile-based extraction with dispersive liquid-liquid microextraction followed by high-performance liquid chromatography.

    PubMed

    Ruan, Chunqiang; Zhao, Xiang; Liu, Chenglan

    2015-09-01

    In this study, a simple and low-organic-solvent-consuming method combining an acetonitrile-partitioning extraction procedure followed by "quick, easy, cheap, effective, rugged and safe" cleanup with ionic-liquid-based dispersive liquid-liquid microextraction and high-performance liquid chromatography with diode array detection was developed for the determination of diflubenzuron and chlorbenzuron in grapes and pears. Ionic-liquid-based dispersive liquid-liquid microextraction was performed using the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate as the extractive solvent and acetonitrile extract as the dispersive solvent. The main factors influencing the efficiency of the dispersive liquid-liquid microextraction were evaluated, including the extractive solvent type and volume and the dispersive solvent volume. The validation parameters indicated the suitability of the method for routine analyses of benzoylurea insecticides in a large number of samples. The relative recoveries at three spiked levels ranged between 98.6 and 109.3% with relative standard deviations of less than 5.2%. The limit of detection was 0.005 mg/kg for the two insecticides. The proposed method was successfully used for the rapid determination of diflubenzuron and chlorbenzuron residues in real fruit samples. PMID:26097091

  12. Determination of diflubenzuron and chlorbenzuron in fruits by combining acetonitrile-based extraction with dispersive liquid-liquid microextraction followed by high-performance liquid chromatography.

    PubMed

    Ruan, Chunqiang; Zhao, Xiang; Liu, Chenglan

    2015-09-01

    In this study, a simple and low-organic-solvent-consuming method combining an acetonitrile-partitioning extraction procedure followed by "quick, easy, cheap, effective, rugged and safe" cleanup with ionic-liquid-based dispersive liquid-liquid microextraction and high-performance liquid chromatography with diode array detection was developed for the determination of diflubenzuron and chlorbenzuron in grapes and pears. Ionic-liquid-based dispersive liquid-liquid microextraction was performed using the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate as the extractive solvent and acetonitrile extract as the dispersive solvent. The main factors influencing the efficiency of the dispersive liquid-liquid microextraction were evaluated, including the extractive solvent type and volume and the dispersive solvent volume. The validation parameters indicated the suitability of the method for routine analyses of benzoylurea insecticides in a large number of samples. The relative recoveries at three spiked levels ranged between 98.6 and 109.3% with relative standard deviations of less than 5.2%. The limit of detection was 0.005 mg/kg for the two insecticides. The proposed method was successfully used for the rapid determination of diflubenzuron and chlorbenzuron residues in real fruit samples.

  13. A strategy for identification and structural characterization of compounds from Gardenia jasminoides by integrating macroporous resin column chromatography and liquid chromatography-tandem mass spectrometry combined with ion-mobility spectrometry.

    PubMed

    Wang, Lu; Liu, Shu; Zhang, Xueju; Xing, Junpeng; Liu, Zhiqiang; Song, Fengrui

    2016-06-24

    In this paper, an analysis strategy integrating macroporous resin (AB-8) column chromatography and high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) combined with ion mobility spectrometry (IMS) was proposed and applied for identification and structural characterization of compounds from the fruits of Gardenia jasminoides. The extracts of G. jasminoides were separated by AB-8 resin column chromatography combined with reversed phase liquid chromatography (C18 column) and detected by electrospray ionization tandem mass spectrometry. Additionally, ion mobility spectrometry (IMS) was employed as a supplementary separation technique to discover previously undetected isomers from the fruits of G. jasminoides. A total of 71 compounds, including iridoids, flavonoids, triterpenes, monoterpenoids, carotenoids and phenolic acids were identified by the characteristic high resolution mass spectrometry and the ESI-MS/MS fragmentations. In conclusion, the IMS-MS technique achieved the separation of isomers in crocin-3 and crocin-4 according to their acquired mobility drift times differing from classical analysis by mass spectrometry. The proposed strategy can be used as a highly sensitive and efficient procedure for identification and separation isomeric components in extracts of herbal medicines.

  14. A strategy for identification and structural characterization of compounds from Gardenia jasminoides by integrating macroporous resin column chromatography and liquid chromatography-tandem mass spectrometry combined with ion-mobility spectrometry.

    PubMed

    Wang, Lu; Liu, Shu; Zhang, Xueju; Xing, Junpeng; Liu, Zhiqiang; Song, Fengrui

    2016-06-24

    In this paper, an analysis strategy integrating macroporous resin (AB-8) column chromatography and high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) combined with ion mobility spectrometry (IMS) was proposed and applied for identification and structural characterization of compounds from the fruits of Gardenia jasminoides. The extracts of G. jasminoides were separated by AB-8 resin column chromatography combined with reversed phase liquid chromatography (C18 column) and detected by electrospray ionization tandem mass spectrometry. Additionally, ion mobility spectrometry (IMS) was employed as a supplementary separation technique to discover previously undetected isomers from the fruits of G. jasminoides. A total of 71 compounds, including iridoids, flavonoids, triterpenes, monoterpenoids, carotenoids and phenolic acids were identified by the characteristic high resolution mass spectrometry and the ESI-MS/MS fragmentations. In conclusion, the IMS-MS technique achieved the separation of isomers in crocin-3 and crocin-4 according to their acquired mobility drift times differing from classical analysis by mass spectrometry. The proposed strategy can be used as a highly sensitive and efficient procedure for identification and separation isomeric components in extracts of herbal medicines. PMID:27208986

  15. Analysis of limonoid glucosides from citrus by electrospray ionization liquid chromatography-mass spectrometry.

    PubMed

    Schoch, T K; Manners, G D; Hasegawa, S

    2001-03-01

    An electrospray ionization liquid chromatography-mass spectrometry (ESI-LC-MS) method for the detection and quantitation of limonoid glucosides has been developed. Negative ions [M - H(+)](-) characteristic of six limonoid glucosides can be detected and quantified from selected ion monitoring chromatograms using carminic acid as an internal standard. The described method has been applied to the analysis of limonoid glucoside content in various liquid and solid Citrus spp. samples as well as complex mixtures of partially purified limonoid glucosides. Rapid and sensitive qualitative screening of samples for limonoid glucosides can also be accomplished with slight modifications of the method. PMID:11312819

  16. Determination of preservatives in cosmetics, cleaning agents and pharmaceuticals using fast liquid chromatography.

    PubMed

    Baranowska, Irena; Wojciechowska, Iwona; Solarz, Natalia; Krutysza, Ewa

    2014-01-01

    This paper reports the development of a method for simultaneously determining five preservatives in cosmetics, cleaning agents and pharmaceuticals by fast liquid chromatography. Methylisothiazolinone, methylchloroisothiazolinone, benzyl alcohol, sodium benzoate and methylparaben were separated on a Chromolith Fast Gradient reversed-phase 18e column using gradient elution with acetonitrile and a 0.1% aqueous solution of formic acid, with a run time of 3 min. The preparation of solid and liquid samples included ultrasonic extraction with methanol with recoveries ranging from 69 to 119%. The developed method was used to analyze samples of cosmetics (66 samples), cleaning agents (five samples) and pharmaceutical industry products (17 samples).

  17. Aerosol matrix-assisted laser desorption ionization for liquid chromatography/time-of-flight mass spectrometry

    SciTech Connect

    Murray, K.K.; Lewis, T.M.; Beeson, M.D.; Russell, D.H. )

    1994-05-15

    We report the application of aerosol matrix-assisted laser desorption ionization (MALDI) to liquid chromatography/mass spectrometry (LC/MS). The aerosol MALDI experiment uses aerosol liquid introduction in conjunction with pulsed UV laser ionization to form ions from large biomolecules in solution. Mass analysis is achieved in a time-of-flight mass spectrometer. In the LC/MALDI-MS experiment, the matrix solution is combined with the column effluent in a mixing tee, LC/MALDI-MS is demonstrated for the separation of bradykinin, gramicidin S, and myoglobin. 32 refs., 8 figs., 1 tab.

  18. Kinetics of decomposition of rabeprazole sodium in aqueous solutions determined by high performance liquid chromatography.

    PubMed

    Mbah, C J

    2007-02-01

    The kinetics of decomposition of rabeprazole sodium in aqueous solutions at elevated temperatures has been investigated by high performance liquid chromatography. The reaction is found to follow first-order kinetics and the rate constant for the degradation at 25 degrees C is estimated by extrapolation. The breakdown of rabeprazole sodium is shown to be water and hydrogen ion catalysed and the effects of ionic strength and buffer concentrations to such rate studies are discussed. PMID:17341029

  19. Quantitative determinations of phenol and resorcinol in pharmaceutical dosage forms by high-pressure liquid chromatography.

    PubMed

    Das Gupta, V

    1976-11-01

    The quantitative determinations of phenol in phenolated calamine lotion USP and of phenol and resorcinol in phenol-resorcinol-boric acid solution by high-pressure liquid chromatography are reported. The procedures are simple, rapid (no special preliminary treatment is required), and accurate. There is no interference from other ingredients of the lotion (bentonite magma, calamine, and zinc oxide) or solution (acetone and boric acid).

  20. High-performance liquid chromatography analysis of plant saponins: An update 2005-2010

    PubMed Central

    Negi, Jagmohan S.; Singh, Pramod; Pant, Geeta Joshi Nee; Rawat, M. S. M.

    2011-01-01

    Saponins are widely distributed in plant kingdom. In view of their wide range of biological activities and occurrence as complex mixtures, saponins have been purified and separated by high-performance liquid chromatography using reverse-phase columns at lower wavelength. Mostly, saponins are not detected by ultraviolet detector due to lack of chromophores. Electrospray ionization mass spectrometry, diode array detector , evaporative light scattering detection, and charged aerosols have been used for overcoming the detection problem of saponins. PMID:22303089

  1. Stability-indicating sulfa drug analysis using high-performance liquid chromatography.

    PubMed

    Umagat, H; McGarry, P F; Tscherne, R J

    1979-07-01

    Sensitive and efficient methods for sulfonamide determination as single entities and in combination with other drug substances in pharmaceutical dosage formulations were developed using high-performance liquid chromatography. These stability-indicating procedures involved a nitrile bonded phase column and nonaqueous mobile phases having diverse polarities. Sample potency was determined using peak height measurements. The methods may be used to determine trace sulfonamide quantities because detection limits are in the nanogram range.

  2. Enantioseparation of chiral pharmaceuticals in biomedical and environmental analyses by liquid chromatography: an overview.

    PubMed

    Ribeiro, Ana R; Maia, Alexandra S; Cass, Quezia B; Tiritan, Maria E

    2014-10-01

    This review aims to present the issues associated to enantioseparation of chiral pharmaceuticals in biological and environmental matrices using chiral stationary phases (CSP). Thus, it related some enantioselective methods in liquid chromatography (LC) and compares the importance given to chiral separation in biomedical and environmental fields. For that the most used CSP, the enantioselective chromatographic methods, their advantages and drawbacks were swiftly revised and compared. The recent advances and the limitations of chiral analytical methods in LC were also discussed.

  3. Determination of dihydroergotamine in human plasma by high-performance liquid chromatography with fluorescence detection.

    PubMed

    Murday, M; McLean, A M; Slaughter, E; Couch, R A

    1999-12-10

    Dihydroergotamine, a 5-hydroxytryptamine antagonist, is used for the treatment of vascular headaches. A high-performance liquid chromatography assay with fluorescence detection is described for the determination of dihydroergotamine in plasma. The assay was validated over the concentration range 0.1-10 ng/ml plasma and applied to the analysis of plasma samples from subjects treated intramuscularly and intranasally with 2 mg of dihydroergotamine. PMID:10670731

  4. Determination of food preservatives and saccharin by high-performance liquid chromatography.

    PubMed

    Leuenberger, U; Gauch, R; Baumgartner, E

    1979-05-21

    The quantitative analysis of benzoic and sorbic acid, methyl, ethyl and propyl esters of p-hydroxybenzoic acid and saccharin in foodstuffs is described. These compounds are quantitatively extracted with disposable clean-up columns packed with Extrelut and simultaneously determined by high-performance liquid chromatography on reversed-phase columns. Complicated matrices such as cheese, cake, ketchup and chocolate were tested and recoveries were generally better than 95% in the concentration ranges normally used in the food industry. PMID:546878

  5. Isolation and Structural Elucidation of an Unknown Impurity in Prasugrel by Semi-Preparative Liquid Chromatography.

    PubMed

    Liu, Chao; Yu, Zhangxin; Wang, Fujun; Zhong, Xing; Jiang, Li; Zhang, Feifei; Tang, Yinxia; Yan, Zhaohua; Zeng, Su; Pu, Tong

    2015-08-01

    A brand-new impurity was detected by RP-HPLC in the prasugrel. The impurity was named as Impurity X. Impurity X was isolated by using semi-preparative HPLC followed by characterization using nuclear magnetic resonance spectroscopy and liquid chromatography-mass spectrometry. The functional mechanism of Impurity X was speculated. Impurity X could be controlled in the manufacture process of the prasugrel active pharmaceutical ingredient effectively. PMID:25644811

  6. Hydrocarbon group type determination in jet fuels by high performance liquid chromatography

    NASA Technical Reports Server (NTRS)

    Antoine, A. C.

    1977-01-01

    Thirty-two jet and diesel fuel samples of varying chemical composition and physical properties were prepared from oil shale and coal syncrudes. Hydrocarbon types in these samples were determined by a fluorescent indicator adsorption analysis, and the results from three laboratories are presented and compared. Two methods of rapid high performance liquid chromatography were used to analyze some of the samples, and these results are also presented and compared. Two samples of petroleum-based Jet A fuel are similarly analyzed.

  7. Analysis of endocrine disrupters and related compounds in sediments and sewage sludge using on-line turbulent flow chromatography-liquid chromatography-tandem mass spectrometry.

    PubMed

    Gorga, Marina; Insa, Sara; Petrovic, Mira; Barceló, Damià

    2014-07-25

    A novel fully automated method based on dual column switching using turbulent flow chromatography followed by liquid chromatography coupled to tandem mass spectrometry (TFC-LC-MS/MS) was applied for the determination of endocrine disruptors (EDCs) and related compounds in sediment and sewage sludge samples. This method allows the unequivocal identification and quantification of the most relevant environmental EDCs such as natural and synthetic estrogens and their conjugates, antimicrobials, parabens, bisphenol A (BPA), alkylphenolic compounds, benzotriazoles, and organophosphorus flame retardants, minimizing time of analysis and alleviating matrix effects. Applying this technique, after the extraction of the target compounds by pressurized liquid extraction (PLE), sediment and sewage sludge extracts were directly injected to the chromatographic system and the analytes were concentrated into the clean-up loading column. Using six-port switching system, the analytes were transferred to the analytical column for subsequent detection by MS-MS (QqQ). In order to optimize this multiplexing system, a comparative study employing six types of TurboFlow™ columns, with different chemical modifications, was performed to achieve the maximum retention of analytes and best elimination of matrix components. Using the optimized protocol low limits of quantification (LOQs) were obtained ranging from 0.0083 to 1.6 ng/g for sediment samples and from 0.10 to 125 ng/g for sewage sludge samples (except for alkylphenol monoethoxylate). The method was used to evaluate the presence and fate of target EDCs in the Ebro River which is the most important river in Spain with intensive agricultural and industrial activities in the basin that contribute to deteriorating soil and water quality. PMID:24909438

  8. Rapid and simple low density miniaturized homogeneous liquid-liquid extraction and gas chromatography/mass spectrometric determination of pesticide residues in sediment.

    PubMed

    Hassan, Jalal; Farahani, Abolfazl; Shamsipur, Mojtaba; Damerchili, Fatemeh

    2010-12-15

    A simple, rapid and environmentally friendly analytical methodology is developed for extraction of pesticides (diazinon, chlorpyrifos and trifluralin) from sediment samples based on a technique called low density miniaturized homogenous liquid-liquid extraction (LDMHLLE) prior gas chromatography mass spectrometry determination. The method based on homogeneous liquid-liquid extraction with methanol containing n-hexane as a solvent of lower density than water (n-hexane). After addition of water, n-hexane solvent immediately forms a distinct water immiscible phase at the top of the vial, which can be easily separated and injected to the GC/MS instrument for quantification. Acquisition was performed in the selected ion monitoring mode. The limits of detection were estimated for the individual pesticides as 3S(b) (three times of the standard deviation of baseline) of the measured chromatogram for pesticides. The proposed method is very fast, simple, and sensitive without any need for stirring and centrifugation and applied to real sediment samples, successfully.

  9. Ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction followed high-performance liquid chromatography for the determination of ultraviolet filters in environmental water samples.

    PubMed

    Zhang, Yufeng; Lee, Hian Kee

    2012-10-31

    In the present study, a rapid, highly efficient and environmentally friendly sample preparation method named ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction (IL-USA-DLLME), followed by high performance liquid chromatography (HPLC) has been developed for the extraction and preconcentration of four benzophenone-type ultraviolet (UV) filters (viz. benzophenone (BP), 2-hydroxy-4-methoxybenzophenone (BP-3), ethylhexyl salicylate (EHS) and homosalate (HMS)) from three different water matrices. The procedure was based on a ternary solvent system containing tiny droplets of ionic liquid (IL) in the sample solution formed by dissolving an appropriate amount of the IL extraction solvent 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIM][FAP]) in a small amount of water-miscible dispersive solvent (methanol). An ultrasound-assisted process was applied to accelerate the formation of the fine cloudy solution, which markedly increased the extraction efficiency and reduced the equilibrium time. Various parameters that affected the extraction efficiency (such as type and volume of extraction and dispersive solvents, ionic strength, pH and extraction time) were evaluated. Under optimal conditions, the proposed method provided good enrichment factors in the range of 354-464, and good repeatability of the extractions (RSDs below 6.3%, n=5). The limits of detection were in the range of 0.2-5.0 ng mL(-1), depending on the analytes. The linearities were between 1 and 500 ng mL(-1) for BP, 5 and 500 ng mL(-1) for BP-3 and HMS and 10 and 500 ng mL(-1) for EHS. Finally, the proposed method was successfully applied to the determination of UV filters in river, swimming pool and tap water samples and acceptable relative recoveries over the range of 71.0-118.0% were obtained. PMID:23062433

  10. Determination of Flavonoids in Wine by High Performance Liquid Chromatography

    NASA Astrophysics Data System (ADS)

    da Queija, Celeste; Queirós, M. A.; Rodrigues, Ligia M.

    2001-02-01

    The experiment presented is an application of HPLC to the analysis of flavonoids in wines, designed for students of instrumental methods. It is done in two successive 4-hour laboratory sessions. While the hydrolysis of the wines is in progress, the students prepare the calibration curves with standard solutions of flavonoids and calculate the regression lines and correlation coefficients. During the second session they analyze the hydrolyzed wine samples and calculate the concentrations of the flavonoids using the calibration curves obtained earlier. This laboratory work is very attractive to students because they deal with a common daily product whose components are reported to have preventive and therapeutic effects. Furthermore, students can execute preparative work and apply a more elaborate technique that is nowadays an indispensable tool in instrumental analysis.

  11. Determination of Niacinamide in Lotions and Creams Using Liquid-Liquid Extraction and High-Performance Liquid Chromatography

    ERIC Educational Resources Information Center

    Usher, Karyn M.; Simmons, Carolyn R.; Keating, Daniel W.; Rossi, Henry F., III

    2015-01-01

    Chemical separations are an important part of an undergraduate chemistry curriculum. Sophomore students often get experience with liquid-liquid extraction in organic chemistry classes, but liquid-liquid extraction is not as often introduced as a quantitative sample preparation method in honors general chemistry or quantitative analysis classes.…

  12. Preparative isolation and analysis of alcohol dehydrogenase inhibitors from Glycyrrhiza uralensis root using ultrafiltration combined with high-performance liquid chromatography and high-speed countercurrent chromatography.

    PubMed

    Chen, Miao; Liu, Liangliang; Chen, Xiaoqing

    2014-07-01

    A simple, rapid, and effective assay based on ultrafiltration combined with high-performance liquid chromatography and high-speed countercurrent chromatography was developed for screening and purifying alcohol dehydrogenase inhibitors from Glycyrrhiza uralensis root extract. Experiments were carried out to optimize binding conditions including alcohol dehydrogenase concentration, incubation time, temperature, and pH. By comparing the chromatograms, three compounds were found possessing alcohol dehydrogenase binding activity in Glycyrrhiza uralensis root. Under the target-guidance of ultrafiltration combined with the high-performance liquid chromatography experiment, liquiritin (1), isoliquiritin (2), and liquiritigenin (3) were separated by high-speed countercurrent chromatography using ethyl acetate/methanol/water (5:1:4) as the solvent system. The alcohol dehydrogenase inhibitory activities of these three isolated compounds were assessed; compound 2 showed strongest inhibitory activity with an IC50 of 8.95 μM. The results of the present study indicated that the combinative method using ultrafiltration, high-performance liquid chromatography and high-speed countercurrent chromatography could be widely applied for the rapid screening and isolation of enzyme inhibitors from complex mixtures.

  13. Solvent-free microextraction techniques in gas chromatography.

    PubMed

    Laaks, Jens; Jochmann, Maik A; Schmidt, Torsten C

    2012-01-01

    Microextraction techniques represent a major part of modern sample preparation in the analysis of organic micropollutants. This article provides a short overview of recent developments in solvent-free microextraction techniques. From the first open-tubular trap techniques in the mid-1980s to recent packed-needle devices, different implementations of in-needle packings for microextraction are discussed with their characteristic benefits, shortcomings and possible sampling modes. Special emphasis is placed on methods providing full automation and solvent exclusion. In this context, in-tube extraction and the needle trap are discussed, with an overview of current research on new sorbent materials, together with the requirements for more efficient method development. PMID:22057686

  14. Screening for low molecular weight compounds in fish meal solubles by hydrophilic interaction liquid chromatography coupled to mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A simple analytical method using hydrophilic interaction liquid chromatography coupled with mass spectrometry was developed to screen for low molecular weight compounds in enzyme treated and untreated Alaskan pollock (Theragra chalcogramma) stickwater (SW) generated from processing fish meal with po...

  15. Determination by liquid chromatography with electrochemical detection of cysteamine and cysteine, possible precursors of N-nitrosothiazolidine

    SciTech Connect

    Pensabene, J.W.; Doerr, R.C.; Fiddler, W.

    1987-11-01

    A method is described that is selective, sensitive, rapid, and accurate for the quantitative measurement in meat products of both cysteamine and cysteine, potential precursors for N-nitrosothiazolidine (NTHZ) and N-nitrosothiazolidine-4-carboxylic acid (NTHZC), respectively. In general, a ground meat sample is homogenized with acetonitrile-formate buffer in the presence of dithiothreitol, and then is centrifuged, filtered, and recentrifuged in a disposable microfilter. The thiols are quantitated by liquid chromatography using an amperometric detector equipped with a gold/mercury electrode, operated in the oxidative mode. Cysteamine was found in 6 of 20 samples of raw pork belly in concentrations ranging from 150 to 450 ppb, and cysteine was found in all samples in concentrations ranging from 2.4 to 36.5 ppm. Analysis for the thiols and their corresponding nitrosamines--NTHZ and NTHZC--of bacon before and after processing showed no correlation between cysteamine and cysteine levels before processing nor with nitrosamine levels after processing. Liquid chromatography with electrochemical detection was found to be an extremely selective technique to measure the 2 free sulfhydryl compounds in a complex food substrate.

  16. Ionic liquids for improving the extraction of NSAIDs in water samples using dispersive liquid-liquid microextraction by high performance liquid chromatography-diode array-fluorescence detection.

    PubMed

    Toledo-Neira, Carla; Álvarez-Lueje, Alejandro

    2015-03-01

    A rapid, sensitive and efficient analytical method based on the use of ionic liquids for determination of non-steroidal anti-inflammatory drugs (NSAIDs) in water samples was developed. High-performance liquid chromatography equipped with a diode array and fluorescence detector was used for quantification of ketoprofen, ibuprofen and diclofenac in tap and river water samples. This new method relies on the use of two ionic liquids with multiple functionalities: one functions as an extraction solvent (1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), and the other changes the polarity in the aqueous medium (1-butyl-3-methylimidazolium tetrafluoroborate, ([BMIM][BF4]). Factors such as the type and volume of the ILs and dispersive solvent, sample volume, and centrifugation time were investigated and optimized. The optimized method exhibited good precision, with relative standard deviation values between 2% and 3%, for the three NSAIDs. Limits of detection achieved for all of the analytes were between 17 and 95 ng mL(-1), and the recoveries ranged from 89% to 103%. Furthermore, the enrichment factors ranged from 49 to 57. The proposed method was successfully applied to the analysis of NSAIDs in tap and river water samples.

  17. Preparation and Characterization of a Polymeric Monolithic Column for Use in High-Performance Liquid Chromatography (HPLC)

    ERIC Educational Resources Information Center

    Bindis, Michael P.; Bretz, Stacey Lowery; Danielson, Neil D.

    2011-01-01

    The high-performance liquid chromatography (HPLC) experiment, most often done in the undergraduate analytical instrumentation laboratory course, generally illustrates reversed-phase chromatography using a commercial C[subscript]18 silica column. To avoid the expense of periodic column replacement and introduce a choice of columns with different…

  18. Determination of nitrofuran metabolites in shrimp by high performance liquid chromatography with fluorescence detection and liquid chromatography-tandem mass spectrometry using a new derivatization reagent.

    PubMed

    Du, Na-Na; Chen, Ming-Ming; Sheng, Liang-Quan; Chen, Shui-Sheng; Xu, Hua-Jie; Liu, Zhao-Di; Song, Chong-Fu; Qiao, Rui

    2014-01-31

    A high performance liquid chromatography with fluorescence detection (HPLC-FLD) method for the simultaneous determination of total nitrofuran metabolite residues (furazolidone, furaltadone, nitrofurantoin, and nitrofurazone) in shrimp was developed. The method involves the acid hydrolysis of protein-bound metabolites, followed by the derivatization of the freed metabolites with the new fluorescent derivatization reagent 2-hydroxy-1-naphthaldehyde (HN) and subsequent liquid-liquid extraction (LLE). Separation is achieved on a YMC-Pack Polymer C18 column under alkaline conditions, and the high fluorescence intensity of the derivatives at an emission wavelength Em=463nm (Ex=395nm) enables, for the first time, their simultaneous determination in shrimp at concentrations as low as 1μg/kg by HPLC-FLD. The method was validated using blank shrimp fortified with all four metabolites at 0.5, 1.0 and 2.0μg/kg. Recoveries were >87% with relative standard deviations of <8.1% for all four metabolites. Furthermore, the results obtained by HPLC-FLD were in very good agreement with those obtained by LC-MS/MS analysis.

  19. Chromatographic behavior of small organic compounds in low-temperature high-performance liquid chromatography using liquid carbon dioxide as the mobile phase.

    PubMed

    Motono, Tomohiro; Nagai, Takashi; Kitagawa, Shinya; Ohtani, Hajime

    2015-07-01

    Low-temperature high-performance liquid chromatography, in which a loop injector, column, and detection cell were refrigerated at -35ºC, using liquid carbon dioxide as the mobile phase was developed. Small organic compounds (polyaromatic hydrocarbons, alkylbenzenes, and quinones) were separated by low-temperature high-performance liquid chromatography at temperatures from -35 to -5ºC. The combination of liquid carbon dioxide mobile phase with an octadecyl-silica (C18 ) column provided reversed phase mode separation, and a bare silica-gel column resulted in normal phase mode separation. In both the cases, nonlinear behavior at approximately -15ºC was found in the relationship between the temperature and the retention factors of the analytes (van't Hoff plots). In contrast to general trends in high-performance liquid chromatography, the decrease in temperature enhanced the separation efficiency of both the columns.

  20. Deformation and degradation of polymers in ultra-high-pressure liquid chromatography.

    PubMed

    Uliyanchenko, Elena; van der Wal, Sjoerd; Schoenmakers, Peter J

    2011-09-28

    Ultra-high-pressure liquid chromatography (UHPLC) using columns packed with sub-2 μm particles has great potential for separations of many types of complex samples, including polymers. However, the application of UHPLC for the analysis of polymers meets some fundamental obstacles. Small particles and narrow bore tubing in combination with high pressures generate significant shear and extensional forces in UHPLC systems, which may affect polymer chains. At high stress conditions flexible macromolecules may become extended and eventually the chemical bonds in the molecules can break. Deformation and degradation of macromolecules will affect the peak retention and the peak shape in the chromatogram, which may cause errors in the obtained results (e.g. the calculated molecular-weight distributions). In the present work we explored the limitations of UHPLC for the analysis of polymers. Degradation and deformation of macromolecules were studied by collecting and re-injecting polymer peaks and by off-line two-dimensional liquid chromatography. Polystyrene standards with molecular weight of 4 MDa and larger were found to degrade at UHPLC conditions. However, for most polymers degradation could be avoided by using low linear velocities. No degradation of 3-MDa PS (and smaller) was observed at linear velocities up to 7 mm/s. The column frits were implicated as the main sources of polymer degradation. The extent of degradation was found to depend on the type of the column and on the column history. At high flow rates degradation was observed without a column being installed. We demonstrated that polymer deformation preceded degradation. Stretched polymers eluted from the column in slalom chromatography mode (elution order opposite to that in SEC or HDC). Under certain conditions we observed co-elution of large and small PS molecules though a convolution of slalom chromatography and hydrodynamic chromatography.

  1. Advanced use of high-performance liquid chromatography for synthesis of controlled metal clusters

    NASA Astrophysics Data System (ADS)

    Niihori, Yoshiki; Matsuzaki, Miku; Uchida, Chihiro; Negishi, Yuichi

    2014-06-01

    Because the synthesis of metal clusters with multiple ligand types results in a distribution of ligands, high-resolution separation of each unique cluster from the mixture is required for precise control of the ligand composition. Reverse-phase high-performance liquid chromatography combined with appropriate transitioning of the mobile phase composition is an extremely effective means of separating ligand combinations when working with metal clusters protected by two different types of thiolates. We report herein advanced use of this method. The studies involving Au24Pd(SR1)18-x(SR2)x and Au24Pd(SR1)18-x(SeR2)x (SR1, SR2 = thiolate, SeR2 = selenolate) revealed the following. (1) In general, an increase in the difference between the polarities of the functional groups incorporated in the two types of ligands improves the separation resolution. A suitable ligand combination for separation can be predicted from the retention times of Au24Pd(SR1)18 and Au24Pd(SR2)18, which cause the terminal peaks in a series of peaks. (2) The use of a step-gradient program during the mobile phase substitution results in improved resolution compared to that achievable with the linear gradients applied in prior work. (3) This technique is also useful for the evaluation of the chemical compositions of metal clusters protected by two different types of ligands with similar molecular weights. These findings will provide clear design guidelines for the functionalization of metal clusters via control of the ligand composition, and will also improve our understanding of the high-resolution isolation of metal clusters.Because the synthesis of metal clusters with multiple ligand types results in a distribution of ligands, high-resolution separation of each unique cluster from the mixture is required for precise control of the ligand composition. Reverse-phase high-performance liquid chromatography combined with appropriate transitioning of the mobile phase composition is an extremely effective

  2. Identification of Clinical Isolates of Mycobacteria with Gas-Liquid Chromatography Alone

    PubMed Central

    Tisdall, Philip A.; Roberts, Glenn D.; Anhalt, John P.

    1979-01-01

    Identification of 18 mycobacterial species was performed by analysis of profiles obtained by using gas-liquid chromatography. Organisms were saponified in methanolic NaOH, and the reaction mixture was treated with BF3 in methanol and extracted with a hexane-chloroform mixture. An identification scheme was developed from 128 stock strains and tested against a collection of 79 clinical isolates. By using gas-liquid chromatographic profiles alone, 58% of specimens were correctly identified to species level, and an additional 41% were correctly identified to a group of two or three organisms. Use in a clinical laboratory over a 2-month period proved chromatography to be as accurate as and more rapid than concurrent biochemical testing. Of 81 isolates tested, 64% were identified to species level by chromatography alone. An additional 35% were differentiated to the same groups of two or three organisms as found in our analysis of stock strains. These groups consisted of: Mycobacterium tuberculosis, M. bovis, and M. xenopi; M. avium complex, M. gastri, and M. scrofulaceum; or M. fortuitum and M. chelonei. Identification to species level from these groups could usually be done by colonial morphology alone and could always be done by the addition of one selected biochemical test. This study demonstrated the practical application of gas-liquid chromatography in the identification of mycobacteria in a clinical laboratory. In particular, all strains of M. gordonae and M. kansasii were identified to species level. M. tuberculosis was definitively identified in 85% of cases. When it could not be definitely identified, the only alternatives were M. bovis and M. xenopi, both of which are rare causes of infection. PMID:118984

  3. Determination of parabens in serum by liquid chromatography-tandem mass spectrometry: Correlation with lipstick use.

    PubMed

    Tahan, Gabriella Padovani; Santos, Nayara de Kássia Souza; Albuquerque, Ana Carolina; Martins, Isarita

    2016-08-01

    Parabens are the most widely used preservative and are considered to be relatively safe compounds. However, studies have demonstrated that they may have estrogenic activity, and there is ongoing debate regarding the safety and potential cancer risk of using products containing these compounds. In the present work, liquid chromatography-tandem mass spectrometry was applied to determine methylparaben and propylparaben concentrations in serum, and the results were correlated with lipstick application. Samples were analyzed using liquid-liquid extraction, followed by liquid chromatography-tandem mass spectrometry. The validation results demonstrated the linearity of the method over a range of 1-20 ng/mL, in addition to the method's precision and accuracy. A statistically significant difference was demonstrated between serum parabens in women who used lipstick containing these substances compared with those not using this cosmetic (p = 0.0005 and 0.0016, respectively), and a strong association was observed between serum parabens and lipstick use (Spearman correlation = 0.7202).

  4. Quantitative analysis of benzodiazepines in vitreous humor by high-performance liquid chromatography

    PubMed Central

    Bazmi, Elham; Behnoush, Behnam; Akhgari, Maryam; Bahmanabadi, Leila

    2016-01-01

    Objective: Benzodiazepines are frequently screened drugs in emergency toxicology, drugs of abuse testing, and in forensic cases. As the variations of benzodiazepines concentrations in biological samples during bleeding, postmortem changes, and redistribution could be biasing forensic medicine examinations, hence selecting a suitable sample and a validated accurate method is essential for the quantitative analysis of these main drug categories. The aim of this study was to develop a valid method for the determination of four benzodiazepines (flurazepam, lorazepam, alprazolam, and diazepam) in vitreous humor using liquid–liquid extraction and high-performance liquid chromatography. Methods: Sample preparation was carried out using liquid–liquid extraction with n-hexane: ethyl acetate and subsequent detection by high-performance liquid chromatography method coupled to diode array detector. This method was applied to quantify benzodiazepines in 21 authentic vitreous humor samples. Linear curve for each drug was obtained within the range of 30–3000 ng/mL with coefficient of correlation higher than 0.99. Results: The limit of detection and quantitation were 30 and 100 ng/mL respectively for four drugs. The method showed an appropriate intra- and inter-day precision (coefficient of variation < 10%). Benzodiazepines recoveries were estimated to be over 80%. The method showed high selectivity; no additional peak due to interfering substances in samples was observed. Conclusion: The present method was selective, sensitive, accurate, and precise for the quantitative analysis of benzodiazepines in vitreous humor samples in forensic toxicology laboratory. PMID:27635251

  5. Quantitative analysis of benzodiazepines in vitreous humor by high-performance liquid chromatography

    PubMed Central

    Bazmi, Elham; Behnoush, Behnam; Akhgari, Maryam; Bahmanabadi, Leila

    2016-01-01

    Objective: Benzodiazepines are frequently screened drugs in emergency toxicology, drugs of abuse testing, and in forensic cases. As the variations of benzodiazepines concentrations in biological samples during bleeding, postmortem changes, and redistribution could be biasing forensic medicine examinations, hence selecting a suitable sample and a validated accurate method is essential for the quantitative analysis of these main drug categories. The aim of this study was to develop a valid method for the determination of four benzodiazepines (flurazepam, lorazepam, alprazolam, and diazepam) in vitreous humor using liquid–liquid extraction and high-performance liquid chromatography. Methods: Sample preparation was carried out using liquid–liquid extraction with n-hexane: ethyl acetate and subsequent detection by high-performance liquid chromatography method coupled to diode array detector. This method was applied to quantify benzodiazepines in 21 authentic vitreous humor samples. Linear curve for each drug was obtained within the range of 30–3000 ng/mL with coefficient of correlation higher than 0.99. Results: The limit of detection and quantitation were 30 and 100 ng/mL respectively for four drugs. The method showed an appropriate intra- and inter-day precision (coefficient of variation < 10%). Benzodiazepines recoveries were estimated to be over 80%. The method showed high selectivity; no additional peak due to interfering substances in samples was observed. Conclusion: The present method was selective, sensitive, accurate, and precise for the quantitative analysis of benzodiazepines in vitreous humor samples in forensic toxicology laboratory.

  6. Determination of parabens in serum by liquid chromatography-tandem mass spectrometry: Correlation with lipstick use.

    PubMed

    Tahan, Gabriella Padovani; Santos, Nayara de Kássia Souza; Albuquerque, Ana Carolina; Martins, Isarita

    2016-08-01

    Parabens are the most widely used preservative and are considered to be relatively safe compounds. However, studies have demonstrated that they may have estrogenic activity, and there is ongoing debate regarding the safety and potential cancer risk of using products containing these compounds. In the present work, liquid chromatography-tandem mass spectrometry was applied to determine methylparaben and propylparaben concentrations in serum, and the results were correlated with lipstick application. Samples were analyzed using liquid-liquid extraction, followed by liquid chromatography-tandem mass spectrometry. The validation results demonstrated the linearity of the method over a range of 1-20 ng/mL, in addition to the method's precision and accuracy. A statistically significant difference was demonstrated between serum parabens in women who used lipstick containing these substances compared with those not using this cosmetic (p = 0.0005 and 0.0016, respectively), and a strong association was observed between serum parabens and lipstick use (Spearman correlation = 0.7202). PMID:27154569

  7. Incorporation of ionic liquid into porous polymer monoliths to enhance the separation of small molecules in reversed-phase high-performance liquid chromatography.

    PubMed

    Wang, Jiafei; Bai, Ligai; Wei, Zhen; Qin, Junxiao; Ma, Yamin; Liu, Haiyan

    2015-06-01

    An ionic liquid was incorporated into the porous polymer monoliths to afford stationary phases with enhanced chromatographic performance for small molecules in reversed-phase high-performance liquid chromatography. The effect of the ionic liquid in the polymerization mixture on the performance of the monoliths was studied in detail. While monoliths without ionic liquid exhibited poor resolution and low efficiency, the addition of ionic liquid to the polymerization mixture provides highly increased resolution and high efficiency. The chromatographic performances of the monoliths were demonstrated by the separations of various small molecules including aromatic hydrocarbons, isomers, and homologues using a binary polar mobile phase. The present column efficiency reached 27 000 plates/m, which showed that the ionic liquid monoliths are alternative stationary phases in the separation of small molecules by high-performance liquid chromatography.

  8. Near infrared spectroscopy compared to liquid chromatography coupled to mass spectrometry and capillary electrophoresis as a detection tool for peptide reaction monitoring.

    PubMed

    Petter, Christine H; Heigl, Nico; Bachmann, Stefan; Huck-Pezzei, Verena A C; Najam-Ul-Haq, Muhammad; Bakry, Rania; Bernkop-Schnürch, Andreas; Bonn, Günther K; Huck, Christian W

    2008-05-01

    Peptide interaction is normally monitored by liquid chromatography (LC), liquid chromatography coupled to mass spectrometry (LC-MS), mass spectrometric (MS) methods such as MALDI-TOF/MS or capillary electrophoresis (CE). These analytical techniques need to apply either high pressure or high voltages, which can cause cleavage of newly formed bondages. Therefore, near infrared reflectance spectroscopy (NIRS) is presented as a rapid alternative to monitor the interaction of glutathione and oxytocin, simulating physiological conditions. Thereby, glutathione can act as a nucleophile with oxytocin forming four new conjugates via a disulphide bondage. Liquid chromatography coupled to UV (LC-UV) and mass spectrometry via an electrospray ionisation interface (LC-ESI-MS) resulted in a 82% and a 78% degradation of oxytocin at pH 3 and a 5% and a 7% degradation at pH 6.5. Capillary electrophoresis employing UV-detection (CE-UV) showed a 44% degradation of oxytocin. LC and CE in addition to the NIRS are found to be authentic tools for quantitative analysis. Nevertheless, NIRS proved to be highly suitable for the detection of newly formed conjugates after separating them on a thin layer chromatography (TLC) plate. The recorded fingerprint in the near infrared region allows for a selective distinct qualitative identification of conjugates without the need for expensive instrumentation such as quadrupole or MALDI-TOF mass spectrometers. The performance of the established NIRS method is compared to LC and CE; its advantages are discussed in detail. PMID:18095054

  9. Rapid determination of phthalate esters in alcoholic beverages by conventional ionic liquid dispersive liquid-liquid microextraction coupled with high performance liquid chromatography.

    PubMed

    Fan, Yingying; Liu, Shuhui; Xie, Qilong

    2014-02-01

    A very simple, fast and environmentally friendly sample extraction method was proposed for the analysis of phthalate esters (PAEs, di-isobutyl phthalate (DIBP), dibutylphthalate (DBP), butylbenzylphthalate (BBP) and bis(2-ethylhexyl)phthalate (DEHP)) in alcoholic beverages by using conventional ionic liquid dispersive liquid-liquid microextraction. The samples were extracted by 160 μL 1-octyl-3-methylimidazolium hexafluorophosphate in the presence of appropriate amount of ethanol and 10% (w/v) sodium chloride solution; the enriched analytes in sedimented phases were analyzed by high performance liquid chromatography-diode array detector (HPLC-DAD). Under the optimum conditions, a satisfactory linearity (in the range of 0.02-1 μg mL(-1) for white spirits and 0.01-0.5 μg mL(-1) for red wines with the correlation coefficients (r) varying from 0.9983 to 1), acceptable recovery rates (88.5-103.5% for white spirits and 91.6-104.6% for red wines), good repeatability (RSD ≤ 8.0%) and low detection limits (3.1-4.2 ng mL(-1) for white spirits and 1.5-2.2 ng mL(-1) for red wines) were obtained. The developed method was successfully applied for the determination of the four PAEs in 30 white spirits and 11 red wines collected locally, and the DBP content in 63% (19:30) white spirits exceeded the specific migration limit of 0.3 mg kg(-1) established by international regulation.

  10. Determination of anabolic agents in dietary supplements by liquid chromatography-high-resolution mass spectrometry.

    PubMed

    Odoardi, Sara; Castrignanò, Erika; Martello, Simona; Chiarotti, Marcello; Strano-Rossi, Sabina

    2015-01-01

    A sensitive method for the identification and quantification of anabolic steroids and clenbuterol at trace levels in dietary supplements by liquid chromatography-high-resolution mass spectrometry (LC-HRMS) in atmospheric pressure ionisation (APCI) mode using a single-stage Orbitrap analyser operating at a resolution power of 100 000 full width at half maximum (FWHM) was developed and validated. A total of 1 g of dietary supplement was added with testosterone-d3 as internal standard, dissolved in methanol, evaporated to dryness, diluted in sodium hydroxide solution and extracted with a mixture of pentane/ethyl ether 9:1. The extract was directly injected into the LC-HRMS system. The method was fully validated. Limits of detection (LODs) obtained for anabolic androgenic steroids (AASs) varied from 1 to 25 ng g(-1) and the limit of quantitation (LOQ) was 50 ng g(-1) for all analytes. The calibration was linear for all compounds in the range from the LOQ to 2000 ng g(-1), with correlation coefficients always higher than 0.99. Accuracy (intended as %E) and repeatability (%CV) were always lower than 15%. Good values of matrix effect and recovery were achieved. The ease of the sample preparation together with a fast run time of only 16 min permitted rapid identification of the analytes. The method was applied to the analysis of 30 dietary supplements in order to check for the presence of anabolic agents not labelled as being present in these supplements. Many AASs were often detected in the same sample: indeed, androstenedione was detected in nine supplements, 5-androsten-3β-ol-17-one (DHEA) in 12, methandienone in three, stanozolol in one, testosterone in seven and testosterone esters in four of them. A retrospective analysis of suspected compounds not included at the beginning of the method development was also possible by means of the full acquisition spectra obtained with the HRMS technique. PMID:25719897

  11. Quantification of free formaldehyde in carrageenan and processed Eucheuma seaweed using high-performance liquid chromatography.

    PubMed

    Hornshøj, Bettina Høj; Kobbelgaard, Sara; Blakemore, William R; Stapelfeldt, Henrik; Bixler, Harris J; Klinger, Markus

    2015-01-01

    In 2010 the European Commission placed a limit on the amount of free formaldehyde in carrageenan and processed Eucheuma seaweed (PES) of 5 mg kg(-1). Formaldehyde is not used in carrageenan and PES processing and accordingly one would not expect free formaldehyde to be present in carrageenan and PES. However, surprisingly high levels up to 10 mg kg(-1) have been found using the generally accepted AOAC and Hach tests. These findings are, per proposed reaction pathways, likely due to the formation of formaldehyde when sulphated galactose, the backbone of carrageenan, is hydrolysed with the strong acid used in these conventional tests. In order to minimise the risk of false-positives, which may lead to regulatory non-compliance, a new high-performance liquid chromatography (HPLC) method has been developed. Initially, carrageenan or PES is extracted with 2-propanol and subsequently reacted with 2,4-dinitrophenylhydrazine (DNPH) to form the chromophore formaldehyde-DNPH, which is finally quantified by reversed-phase HPLC with ultraviolet light detection at 355 nm. This method has been found to have a limit of detection of 0.05 mg kg(-1) and a limit of quantification of 0.2 mg kg(-1). Recoveries from samples spiked with known quantities of formaldehyde were 95-107%. Using this more specific technique, 20 samples of carrageenan and PES were tested for formaldehyde. Only one sample had a detectable content of formaldehyde (0.40 mg kg(-1)), thus demonstrating that the formaldehyde content of commercial carrageenan and PES products are well below the European Commission maximum limit of 5 mg kg(-1).

  12. Investigation of isovaline enantiomeric excesses in CM meteorites using liquid chromatography time of flight mass spectrometry

    NASA Technical Reports Server (NTRS)

    Glavin, Daniel P.; Dworkin, Jason P.

    2003-01-01

    The enantiomeric abundances of the alpha-dialkyl amino acid isovaline were measured in the CM2 meteorites Murchison and LEW 90500 using a new liquid chromatography-time of flight-mass spectrometry (LC-ToF-MS) technique coupled with OPA/NAC derivatization and UV fluorescence detection. Previous analyses of Murchison have shown that L-enantiomeric excesses of isovaline range from 0 to 15.2% with significant variation between meteorite fragments [1]. For this study, hot water extracts of interior fragments (> 2 cm from fusion crust) of the Murchison (USNM 6650.2, mass 6 g) and LEW 90500 (split 69, parent 1, mass 5 g) carbonaceous meteorites were analyzed. Enantiomeric excesses were measured using the single ion LC-ToF-MS trace for the OPA/NAC derivative of isovaline at d z 393.15 (Fig. 1). L-isovaline excesses in these meteorite samples ranged from 18.9 to 20.5% for Murchison and -0.5 to 3.0% for LEW 90500. The measured values for Murchison are the largest enantiomeric excesses for isovaline reported to date. The enantiomeric excesses of L-isovaline cannot be the result of interference from other C5 amino acid isomers present in the meteorites or terrestrial contamination from the landing site environments. The L-isovaline excesses in Murchison are inconsistent with the synthesis of all of the isovaline by the Strecker-cyanohydrin pathway on the CM meteorite parent body. The mechanism(s) for the formation of the enantiomeric asymmetry in isovaline in Murchison are currently unknown and it is not clear how the asymmetry of alpha-dialkyl amino acids could be transferred to the a-hydrogen protein amino acids common in all life on Earth today.

  13. Determination of multiple human arsenic metabolites employing high performance liquid chromatography inductively coupled plasma mass spectrometry.

    PubMed

    Stice, Szabina; Liu, Guangliang; Matulis, Shannon; Boise, Lawrence H; Cai, Yong

    2016-01-15

    During the metabolism of different arsenic-containing compounds in human, a variety of metabolites are produced with significantly varying toxicities. Currently available analytical methods can only detect a limited number of human metabolites in biological samples during one run due to their diverse characteristics. In addition, co-elution of species is often unnoticeable with most detection techniques leading to inaccurate metabolic profiles and assessment of toxicity. A high performance liquid chromatography inductively coupled mass spectrometry (HPLC-ICP-MS) method was developed that can identify thirteen common arsenic metabolites possibly present in human with special attention dedicated to thiolated or thiol conjugated arsenicals. The thirteen species included in this study are arsenite (As(III)), arsino-glutathione (As(GS)3), arsenate (As(V)), monomethylarsonous acid (MMA(III)), monomethylarsino-glutathione (MMA(III)(GS) 2), monomethylarsonic acid (MMA(V)), dimethylarsinous acid (DMA(III) (from DMA(III)I)), S-(dimethylarsinic)cysteine (DMA(III) (Cys)), dimethylarsino-glutathione (DMA(III)(GS)), dimethylarsinic acid (DMA(V)), dimethylmonothioarsinic acid (DMMTA(V)), dimethyldithioarsinic acid (DMDTA(V)), dimethylarsinothioyl glutathione (DMMTA(V)(GS)). The developed method was applied for the analysis of cancer cells that were incubated with darinaparsin (DMA(III)(GS)), a novel chemotherapeutic agent for refractory malignancies, and the arsenic metabolic profile obtained was compared to results using a previously developed method. This method provides a useful analytical tool which is much needed in unequivocally identifying the arsenicals formed during the metabolism of environmental arsenic exposure or therapeutic arsenic administration.

  14. Determination of anabolic agents in dietary supplements by liquid chromatography-high-resolution mass spectrometry.

    PubMed

    Odoardi, Sara; Castrignanò, Erika; Martello, Simona; Chiarotti, Marcello; Strano-Rossi, Sabina

    2015-01-01

    A sensitive method for the identification and quantification of anabolic steroids and clenbuterol at trace levels in dietary supplements by liquid chromatography-high-resolution mass spectrometry (LC-HRMS) in atmospheric pressure ionisation (APCI) mode using a single-stage Orbitrap analyser operating at a resolution power of 100 000 full width at half maximum (FWHM) was developed and validated. A total of 1 g of dietary supplement was added with testosterone-d3 as internal standard, dissolved in methanol, evaporated to dryness, diluted in sodium hydroxide solution and extracted with a mixture of pentane/ethyl ether 9:1. The extract was directly injected into the LC-HRMS system. The method was fully validated. Limits of detection (LODs) obtained for anabolic androgenic steroids (AASs) varied from 1 to 25 ng g(-1) and the limit of quantitation (LOQ) was 50 ng g(-1) for all analytes. The calibration was linear for all compounds in the range from the LOQ to 2000 ng g(-1), with correlation coefficients always higher than 0.99. Accuracy (intended as %E) and repeatability (%CV) were always lower than 15%. Good values of matrix effect and recovery were achieved. The ease of the sample preparation together with a fast run time of only 16 min permitted rapid identification of the analytes. The method was applied to the analysis of 30 dietary supplements in order to check for the presence of anabolic agents not labelled as being present in these supplements. Many AASs were often detected in the same sample: indeed, androstenedione was detected in nine supplements, 5-androsten-3β-ol-17-one (DHEA) in 12, methandienone in three, stanozolol in one, testosterone in seven and testosterone esters in four of them. A retrospective analysis of suspected compounds not included at the beginning of the method development was also possible by means of the full acquisition spectra obtained with the HRMS technique.

  15. Designer psychostimulants in urine by liquid chromatography-tandem mass spectrometry.

    PubMed

    Kerrigan, Sarah; Mott, Ashley; Jatzlau, Breanna; Ortiz, Francisco; Perrella, Laura; Martin, Sarah; Bryand, Kelsie

    2014-01-01

    Designer psychostimulants are known by recreational drug users to produce a complex array of adrenergic and hallucinogenic effects. Many of these drugs are not targeted during routine toxicology testing and as a consequence, they are rarely reported. The purpose of this study was to develop a procedure for the detection of 15 psychostimulants in urine using liquid chromatography-tandem mass spectrometry (LC-MS/MS), specifically 2,5-dimethoxy-4-bromophenethylamine (2C-B), 2,5-dimethoxy-4-chlorophenethylamine (2C-C), 2,5-dimethoxy-4-methylphenethylamine (2C-D), 2,5-dimethoxy-4-ethylphenethylamine (2C-E), 2,5-dimethoxyphenethylamine (2C-H), 2,5-dimethoxy-4-iodophenethylamine (2C-I), 2,5-dimethoxy-4-ethylthiophenethylamine (2C-T-2), 2,5-dimethoxy-4-isopropylthiophenethylamine (2C-T-4), 2,5-dimethoxy-4-propylthiophenethylamine (2C-T-7), 2,5-dimethoxy-4-bromoamphetamine (DOB), 2,5-dimethoxy-4-chloroamphetamine (DOC), 2,5-dimethoxy-4-ethylamphetamine (DOET), 2,5-dimethoxy-4-iodoamphetamine (DOI), 2,5-dimethoxy-4-methylamphetamine (DOM), and 4-methylthioamphetamine (4-MTA). Analytical recoveries using solid-phase extraction were 64-92% and the limit of detection was 0.5 ng/mL for all drugs except 2C-B (1 ng/mL). The assay was evaluated in terms of analytical recovery, precision, accuracy, linearity, matrix effect, and interferences. The technique allows for the simultaneous detection of 15 psychostimulants at sub-ng/mL concentrations.

  16. Quantification of free formaldehyde in carrageenan and processed Eucheuma seaweed using high-performance liquid chromatography.

    PubMed

    Hornshøj, Bettina Høj; Kobbelgaard, Sara; Blakemore, William R; Stapelfeldt, Henrik; Bixler, Harris J; Klinger, Markus

    2015-01-01

    In 2010 the European Commission placed a limit on the amount of free formaldehyde in carrageenan and processed Eucheuma seaweed (PES) of 5 mg kg(-1). Formaldehyde is not used in carrageenan and PES processing and accordingly one would not expect free formaldehyde to be present in carrageenan and PES. However, surprisingly high levels up to 10 mg kg(-1) have been found using the generally accepted AOAC and Hach tests. These findings are, per proposed reaction pathways, likely due to the formation of formaldehyde when sulphated galactose, the backbone of carrageenan, is hydrolysed with the strong acid used in these conventional tests. In order to minimise the risk of false-positives, which may lead to regulatory non-compliance, a new high-performance liquid chromatography (HPLC) method has been developed. Initially, carrageenan or PES is extracted with 2-propanol and subsequently reacted with 2,4-dinitrophenylhydrazine (DNPH) to form the chromophore formaldehyde-DNPH, which is finally quantified by reversed-phase HPLC with ultraviolet light detection at 355 nm. This method has been found to have a limit of detection of 0.05 mg kg(-1) and a limit of quantification of 0.2 mg kg(-1). Recoveries from samples spiked with known quantities of formaldehyde were 95-107%. Using this more specific technique, 20 samples of carrageenan and PES were tested for formaldehyde. Only one sample had a detectable content of formaldehyde (0.40 mg kg(-1)), thus demonstrating that the formaldehyde content of commercial carrageenan and PES products are well below the European Commission maximum limit of 5 mg kg(-1). PMID:25531040

  17. A sliding cell technique for diffusion measurements in liquid metals

    SciTech Connect

    Geng, Yongliang; Zhu, Chunao; Zhang, Bo

    2014-03-15

    The long capillary and shear cell techniques are the usual methods for diffusion measurements in liquid metals. Here we present a new “sliding cell technique” to measure interdiffusion in liquid alloys, which combines the merits of these two methods. Instead of a number of shear cells, as used in the shear cell method, only one sliding cell is designed to separate and join the liquid diffusion samples. Using the sliding cell technique, the influence of the heating process (which affects liquid diffusion measurements in the conventional long capillary method) can be eliminated. Time-dependent diffusion measurements at the same isothermal temperature were carried out in Al-Cu liquids. Compared with the previous results measured by in-situ X-ray radiography, the obtained liquid diffusion coefficient in this work is believed to be influenced by convective flow. The present work further supports the idea that to obtain accurate diffusion constants in liquid metals, the measurement conditions must be well controlled, and there should be no temperature gradients or other disturbances.

  18. Extraction and determination of hormones in cosmetics by homogeneous ionic liquid microextraction high-performance liquid chromatography.

    PubMed

    Kang, Mingqin; Sun, Shuo; Li, Na; Zhang, Daihui; Chen, Mingyan; Zhang, Hanqi

    2012-08-01

    The homogeneous ionic liquid microextraction was applied to the extraction of hormones from cosmetics and the hormones were determined by high-performance liquid chromatography. 1-Hexyl-3-methylimidazolium tetrafluoroborate was used as extraction solvent. Ammonium hexafluorophosphate as used as ion-pairing agent. Several experimental parameters, including the volume of 1-hexyl-3-methylimidazolium tetrafluoroborate, amount of ammonium hexafluorophosphate and sodium chloride, extraction and centrifuge time, and the pH value, were optimized. The limits of detection and quantification for the analytes ranged from 0.03 to 0.24 ng/mL and from 0.10 to 0.79 ng/mL, respectively. The precision for determining the hormones was lower than 5.2%. The proposed method was successfully developed for the determination of hormones in real cosmetic samples.

  19. Formation of iron complexs from trifluoroacetic acid based liquid chromatography mobile phases as interference ions in liquid chromatography/electrospray ionization mass spectrometric analysis

    SciTech Connect

    Shukla, Anil K.; Zhang, Rui; Orton, Daniel J.; Zhao, Rui; Clauss, Therese RW; Moore, Ronald J.; Smith, Richard D.

    2011-05-30

    Two unexpected singly charged ions at m/z 1103 and 944 have been observed in mass spectra obtained from electrospray ionization-mass spectrometric analysis of liquid chromatography effluents with mobile phases containing trifluoroacetic acid. Accurate mass measurement and tandem mass spectrometry studies revealed that these two ions are not due to any contamination from solvents and chemicals used for mobile and stationary phases or from the laboratory atmospheric environment. Instead these ions are clusters of trifluoroacetic acid formed in association with acetonitrile, water and iron from the stainless steel union used to connect the column with the electrospray tip and to apply high voltage; the molecular formulae are Fe+((OH)(H2O)2)9(CF3COOH)5 and Fe+((OH)(H2O)2)6 (CF3COOH)5.

  20. Development and application of a dispersive liquid-liquid microextraction method for the determination of tetracyclines in beef by liquid chromatography mass spectrometry.

    PubMed

    Mookantsa, S O S; Dube, S; Nindi, M M

    2016-02-01

    A rapid, cost effective and environmentally friendly extraction method, based on dispersive liquid-liquid microextraction (DLLME) was developed for the determination of six tetracyclines in meat destined for human consumption. Meat extracts were analysed for tetracyclines using liquid chromatography tandem mass spectrometry (LC-MS/MS), a sensitive and selective analytical technique. Various factors influencing the pre-concentration of tetracyclines such as sample pH, type and volume of both disperser solvent and extraction solvent were optimized. Validation parameters such as calibration function, limit of detection (LOD), limit of quantification (LOQ), detection capability (CCα), decision limit (CCβ), accuracy and precision were established according to Commission Decision 2002/657/EC. Linearity in the range of 25-200 µg kg(-1) was obtained with regression coefficients ranging from 0.9991 to 0.9998. Recoveries of spiked blank muscle samples at three levels (50, 100 and 150 µg kg(-1)) ranged from 80% to 105% and reproducibility was between 2% and 7%. LODs and LOQs ranged from 2.2 to 3.6 µg kg(-1) and from 7.4 to 11.5 µg kg(-1) respectively while CCα ranged from 105 to 111 µg kg(-1) and CCβ ranged from 107 to 122 µg kg(-1). The proposed method compared well with the existing accepted dispersive solid phase extraction method and was successfully applied to the pre-concentration and determination of tetracyclines in meat samples. Eleven of the thirty bovine muscle samples obtained from local abattoirs and butcheries were found to contain residues of two tetracycline antibiotics (chlortetracycline and oxytetracycline), with oxytetracycline being the most detected. Concentration levels of the tetracycline residues detected in bovine muscle samples were lower (12.4 and 68.9 µg kg(-1)) than the stipulated European Union maximum residue level (MRL) of 100 µg kg(-1), hence the meat was fit for human consumption. From this work it can be concluded that the DLLME