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Sample records for single-step liquid chromatography

  1. 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.

  2. Single-step multiresidue determination of ten multiclass veterinary drugs in pork, milk, and eggs using liquid chromatography with tandem mass spectrometry.

    PubMed

    Park, Jin-A; Zhang, Dan; Kim, Dong-Soon; Kim, Seong-Kwan; Cho, Kyeong-Su; Jeong, Dana; Shim, Jae-Han; Kim, Jin-Suk; Abd El-Aty, A M; Shin, Ho-Chul

    2015-08-01

    A multiclass, multiresidue determination method is reported for the detection of ten veterinary drugs, including scopolamine, metoclopramide, acriflavine, berberine, tripelennamine, diphenhydramine, acrinol, triamcinolone, loperamide, and roxithromycin in pork, milk, and eggs. The method involves a simple extraction using 0.1% formic acid in acetonitrile, followed by defatting with n-hexane, centrifugation, and filtration prior to liquid chromatography with tandem mass spectrometric analysis. As ion suppression and enhancement effects are reported, matrix-matched calibrations are used for quantification, with determination coefficients ≥0.9765. For the majority of the tested analytes, the intra- and interday accuracy (expressed as recovery %) range from 70.6 to 94.6% and from 70.1 to 93.3%, respectively, and the precision (expressed as relative standard deviation) ranges from 0.5 to 19.8% and from 2.8 to 18.4% in all matrices. The limits of quantification range between 0.5 and 10 ng/g. The validated tandem mass spectrometry method is successfully applied to market samples; the target analytes are not detected in any of the tested samples. In terms of accuracy, no extract cleanup is deemed necessary. The developed method is feasible for the simultaneous detection of the tested analytes in pork, milk, and eggs.

  3. A single-step solid phase extraction for the simultaneous determination of 8 mycotoxins in fruits by ultra-high performance liquid chromatography tandem mass spectrometry.

    PubMed

    Wang, Meng; Jiang, Nan; Xian, Hong; Wei, Dizhe; Shi, Lei; Feng, Xiaoyuan

    2016-01-15

    A simple and rapid extraction procedure for the simultaneous determination of eight mycotoxins (Alternaria toxins, ochratoxin A, patulin, citrinin) in a variety of fruit matrices has been developed using ultra high performance liquid chromatography coupled to tandem mass spectrometry. The procedure involves a one-step cleanup using homemade solid phase extraction (SPE) cartridges. By comparative evaluation among six various adsorbents (C18, PSA, HLB, MCX, Silica, NH2), the combination of MCX and NH2 was found to provide the most effective cleanup, removing the greatest number of matrix interferences and also allowing the quantification of all analyzed mycotoxins in fruits. The optimized extraction conditions including acidified aqueous acetonitrile and an additional salt-out step using NaCl were employed before SPE cleanup. Method validation was performed by analyzing samples spiked at three levels (LOQ, 2 LOQ and 10 LOQ). Four fruits including apple, sweet cherry, tomato and orange fruits were selected, and accuracy (recovery%), precision (RSD%), limits of quantification (LOQ), linearity and matrix effect were evaluated during validation. Matrix-matched linearity with correlation coefficients ≥ 0.9921 was established in the range of 5-200 ng mL(-1) for patulin and 1-200 ng mL(-1) for other mycotoxins, respectively. Recoveries between 74.2% and 102.4% and relative standard deviations lower than 4.7% were obtained for all tested fruits. The matrix effect observed was low (≤ ± 17%) in all three fruit matrixes with the exception of orange, for which strong ion suppression was observed for alternariol (25.3%), ochratoxin A (31.6%) and citrinin (40.3%). Therefore, matrix-matched calibration was used for a correct quantification in order to compensate for matrix effect. The limits of quantification (LOQ), ranging from 1 to 5 μg kg(-1) depending on mycotoxins type, were always lower than maximum permitted levels for every regulated mycotoxin by the current European

  4. Single-step purification of F(ab')2 fragments of mouse monoclonal antibodies (immunoglobulins G1) by hydrophobic interaction high performance liquid chromatography using TSKgel Phenyl-5PW.

    PubMed

    Morimoto, K; Inouye, K

    1992-03-01

    Hydrophobic interaction high performance liquid chromatography (HPLC) using TSKgel Phenyl-5PW was applicable to single-step purification of F(ab')2 fragments from pepsin digests of mouse monoclonal antibodies of IgG1 class. The digests were applied to the gel equilibrated with phosphate-buffered saline containing 1 M ammonium sulfate. F(ab')2 fragments were adsorbed onto the gel using the same buffer, and eluted by reducing the ammonium sulfate concentration to 0 M. The fraction containing F(ab')2 fragments was homogeneous (purity: higher than 98%) by both sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration HPLC. The recovery of the antigen binding site was 42-58%. The cycle time of the Phenyl-5PW HPLC was 45 min, and F(ab')2 of up to 2200 mg was purified in a cycle. This method could be useful especially for large scale purification of F(ab')2 fragments.

  5. Single-step purification of native miraculin using immobilized metal-affinity chromatography.

    PubMed

    Duhita, Narendra; Hiwasa-Tanase, Kyoko; Yoshida, Shigeki; Ezura, Hiroshi

    2009-06-24

    Miraculin is a taste-modifying protein that can be isolated from miracle fruit ( Richadella dulcifica ), a shrub native to West Africa. It is able to turn a sour taste into a sweet taste. The commercial exploitation of this sweetness-modifying protein is underway, and a fast and efficient purification method to extract the protein is needed. We succeeded in purifying miraculin from miracle fruit in a single-step purification using immobilized metal-affinity chromatography (IMAC). The purified miraculin exhibited high purity (>95%) in reverse-phase high-performance liquid chromatography. We also demonstrated the necessity of its structure for binding to the nickel-IMAC column.

  6. Combined Protein A and size exclusion high performance liquid chromatography for the single-step measurement of mAb, aggregates and host cell proteins.

    PubMed

    Gjoka, Xhorxhi; Schofield, Mark; Cvetkovic, Aleksandar; Gantier, Rene

    2014-12-01

    Quantification of monoclonal antibody (mAb) monomer, mAb aggregates, and host cell proteins (HCPs) is critical for the optimization of the mAb production process. The present work describes a single high throughput analytical tool capable of tracking the concentration of mAb, mAb aggregate and HCPs in a growing cell culture batch. By combining two analytical HPLC methods, Protein A affinity and size-exclusion chromatography (SEC), it is possible to detect a relative increase or decrease in the concentration of all three entities simultaneously. A comparison of the combined Protein A-SEC assay to SEC alone was performed, demonstrating that it can be useful tool for the quantification of mAb monomer along with trending data for mAb aggregate and HCP. Furthermore, the study shows that the Protein A-SEC method is at least as accurate as other commonly used analytical methods such as ELISA and Bradford.

  7. Single-step purification of F(ab')2 mu fragments of mouse monoclonal antibodies (immunoglobulins M) by hydrophobic interaction high-performance liquid chromatography using TSKgel ether-5PW.

    PubMed

    Inouye, K; Morimoto, K

    1993-02-01

    A procedure is described for preparation and single-step purification of F(ab')2 fragments, herein designated as F(ab')2 mu' from mouse monoclonal antibodies of the IgM class. Hydrophobic interaction high-performance liquid chromatography (HPLC) using TSKgel Ether-5PW was well applicable to the purification. The IgM was digested with pepsin at the pepsin-to-IgM ratio of 1:200 (w/w) in 100 mM citrate buffer (pH 4.2) at 37 degrees C for 2 h. The digests were applied to the gel equilibrated with the buffer containing 1 M ammonium sulfate. F(ab')2 mu fragments were adsorbed onto the gel with the same buffer, and eluted by reducing the ammonium sulfate concentration to 0 M. The fraction containing F(ab')2 mu fragments was homogeneous (purity higher than 97%) by both sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel-filtration HPLC. The recovery of the antigen-binding site was 55-72%. The cycle time of the Ether-5PW HPLC was 40 min, and up to 98 mg F(ab')2 mu fragments. The molecular mass of F(ab')2 mu was estimated to be 144-146 kDa. In comparison with IgM, F(ab')2 mu lost entirely the complement C1q binding activity, and the sugar content was greatly reduced. The binding of IgM with non-specific proteins turned to be negligible, when IgM was converted to F(ab')2 mu, suggesting that the fragments are useful for immunological application.

  8. Mercury speciation by high-performance liquid chromatography atomic fluorescence spectrometry using an integrated microwave/UV interface. Optimization of a single step procedure for the simultaneous photo-oxidation of mercury species and photo-generation of Hg0

    NASA Astrophysics Data System (ADS)

    de Quadros, Daiane P. C.; Campanella, Beatrice; Onor, Massimo; Bramanti, Emilia; Borges, Daniel L. G.; D'Ulivo, Alessandro

    2014-11-01

    We described the hyphenation of photo-induced chemical vapor generation with high performance liquid chromatography-atomic fluorescence spectrometry (HPLC-AFS) for the quantification of inorganic mercury, methylmercury (MeHg) and ethylmercury (EtHg). In the developed procedure, formic acid in mobile phase was used for the photodecomposition of organomercury compounds and reduction of Hg2 + to mercury vapor under microwave/ultraviolet (MW/UV) irradiation. We optimized the proposed method studying the influence of several operating parameters, including the type of organic acid and its concentration, MW power, composition of HPLC mobile phase and catalytic action of TiO2 nanoparticles. Under the optimized conditions, the limits of detection were 0.15, 0.15 and 0.35 μg L- 1 for inorganic mercury, MeHg and EtHg, respectively. The developed method was validated by determination of the main analytical figures of merit and applied to the analysis of three certified reference materials. The online interfacing of liquid chromatography with photochemical-vapor generation-atomic fluorescence for mercury determination is simple, environmentally friendly, and represents an attractive alternative to the conventional tetrahydroborate (THB) system.

  9. Separation of Be and Al for AMS using single-step column chromatography

    NASA Astrophysics Data System (ADS)

    Binnie, Steven A.; Dunai, Tibor J.; Voronina, Elena; Goral, Tomasz; Heinze, Stefan; Dewald, Alfred

    2015-10-01

    With the aim of simplifying AMS target preparation procedures for TCN measurements we tested a new extraction chromatography approach which couples an anion exchange resin (WBEC) to a chelating resin (Beryllium resin) to separate Be and Al from dissolved quartz samples. Results show that WBEC-Beryllium resin stacks can be used to provide high purity Be and Al separations using a combination of hydrochloric/oxalic and nitric acid elutions. 10Be and 26Al concentrations from quartz samples prepared using more standard procedures are compared with results from replicate samples prepared using the coupled WBEC-Beryllium resin approach and show good agreement. The new column procedure is performed in a single step, reducing sample preparation times relative to more traditional methods of TCN target production.

  10. Single-Step Purification of Monomeric l-Selectin via Aptamer Affinity Chromatography

    PubMed Central

    Kuehne, Christian; Wedepohl, Stefanie; Dernedde, Jens

    2017-01-01

    l-selectin is a transmembrane receptor expressed on the surface of white blood cells and responsible for the tethering of leukocytes to vascular endothelial cells. This initial intercellular contact is the first step of the complex leukocyte adhesion cascade that ultimately permits extravasation of leukocytes into the surrounding tissue in case of inflammation. Here we show the binding of a soluble histidine tagged l-selectin to a recently described shortened variant of an l-selectin specific DNA aptamer with surface plasmon resonance. The high specificity of this aptamer in combination with its high binding affinity of ~12 nM, allows for a single-step protein purification from cell culture supernatants. In comparison to the well-established Ni-NTA based technology, aptamer affinity chromatography (AAC) was easier to establish, resulted in a 3.6-fold higher protein yield, and increased protein purity. Moreover, due to target specificity, the DNA aptamer facilitated binding studies directly from cell culture supernatant, a helpful characteristic to quickly monitor successful expression of biological active l-selectin. PMID:28125045

  11. Single-step total fractionation of single-wall carbon nanotubes by countercurrent chromatography

    PubMed Central

    Zhang, Min; Khripin, Constantine Y; Fagan, Jeffrey A.; McPhie, Peter; Ito, Yoichiro; Zheng, Ming

    2014-01-01

    Development of simple processes to fractionate synthetic mixtures of single-wall carbon nanotubes (SWCNTs) into individual species is crucial to many applications. Existing methods for single-chirality SWCNT purification are cumbersome, often requiring multiple steps and different conditions for different species. Here, we report a method to achieve total fractionation of a synthetic SWCNT mixture by countercurrent chromatography, resulting in purification of many single-chirality SWCNT species in a single run. This method is based on tunable partition of sodium deoxycholate dispersed SWCNTs in polyethylene glycol / dextran aqueous two-phase system. By running the mobile phase with 0.02% of sodium deoxycholate and a gradient of sodium dodecyl sulfate from 0.1% to 0.7% (w/w), we observe clear diameter-dependent elution, with ~ 90% total recovery. Among all the fractions collected, a number of them are enriched in single-chirality (9,4), (7,5), (7,6), (8,3), (6,5) species, while most of the remaining ones contain no more than 2-3 major species. We also observe strong (n,m)-dependent elution peak width due to enantiomer-resolved partition. These results demonstrate CCC as an effective way to obtain high purity (n, m) species, and suggest the potential of CCC as an analytical tool for chirality distribution mapping of synthetic SWCNT mixtures. PMID:24673411

  12. A novel multimodal chromatography based single step purification process for efficient manufacturing of an E. coli based biotherapeutic protein product.

    PubMed

    Bhambure, Rahul; Gupta, Darpan; Rathore, Anurag S

    2013-11-01

    Methionine oxidized, reduced and fMet forms of a native recombinant protein product are often the critical product variants which are associated with proteins expressed as bacterial inclusion bodies in E. coli. Such product variants differ from native protein in their structural and functional aspects, and may lead to loss of biological activity and immunogenic response in patients. This investigation focuses on evaluation of multimodal chromatography for selective removal of these product variants using recombinant human granulocyte colony stimulating factor (GCSF) as the model protein. Unique selectivity in separation of closely related product variants was obtained using combined pH and salt based elution gradients in hydrophobic charge induction chromatography. Simultaneous removal of process related impurities was also achieved in flow-through leading to single step purification process for the GCSF. Results indicate that the product recovery of up to 90.0% can be obtained with purity levels of greater than 99.0%. Binding the target protein at pH

  13. Single-Step Fabrication of Computationally Designed Microneedles by Continuous Liquid Interface Production

    PubMed Central

    Johnson, Ashley R.; Caudill, Cassie L.; Tumbleston, John R.; Bloomquist, Cameron J.; Moga, Katherine A.; Ermoshkin, Alexander; Shirvanyants, David; Mecham, Sue J.; Luft, J. Christopher; DeSimone, Joseph M.

    2016-01-01

    Microneedles, arrays of micron-sized needles that painlessly puncture the skin, enable transdermal delivery of medications that are difficult to deliver using more traditional routes. Many important design parameters, such as microneedle size, shape, spacing, and composition, are known to influence efficacy, but are notoriously difficult to alter due to the complex nature of microfabrication techniques. Herein, we utilize a novel additive manufacturing (“3D printing”) technique called Continuous Liquid Interface Production (CLIP) to rapidly prototype sharp microneedles with tuneable geometries (size, shape, aspect ratio, spacing). This technology allows for mold-independent, one-step manufacturing of microneedle arrays of virtually any design in less than 10 minutes per patch. Square pyramidal CLIP microneedles composed of trimethylolpropane triacrylate, polyacrylic acid and photopolymerizable derivatives of polyethylene glycol and polycaprolactone were fabricated to demonstrate the range of materials that can be utilized within this platform for encapsulating and controlling the release of therapeutics. These CLIP microneedles effectively pierced murine skin ex vivo and released the fluorescent drug surrogate rhodamine. PMID:27607247

  14. 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)

  15. 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.

  16. 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,…

  17. Selective Single-Step Separation of a Mixture of Three Metal Ions by a Triphasic Ionic-Liquid-Water-Ionic-Liquid Solvent Extraction System.

    PubMed

    Vander Hoogerstraete, Tom; Blockx, Jonas; De Coster, Hendrik; Binnemans, Koen

    2015-08-10

    In a conventional solvent extraction system, metal ions are distributed between two immiscible phases, typically an aqueous and an organic phase. In this paper, the proof-of-principle is given for the distribution of metal ions between three immiscible phases, two ionic liquid phases with an aqueous phase in between them. Three-liquid-phase solvent extraction allows separation of a mixture of three metal ions in a single step, whereas at least two steps are required to separate three metals in the case of two-liquid-phase solvent extraction. In the triphasic system, the lower organic phase is comprised of the ionic liquid betainium- or choline bis(trifluoromethylsulfonyl)imide, whereas the upper organic phase is comprised of the ionic liquid trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide. The triphasic system was used for the separation of a mixture of tin(II), yttrium(III), and scandium(III) ions.

  18. Combination of Electromembrane Extraction and Liquid-Phase Microextraction in a Single Step: Simultaneous Group Separation of Acidic and Basic Drugs.

    PubMed

    Huang, Chuixiu; Seip, Knut Fredrik; Gjelstad, Astrid; Shen, Xiantao; Pedersen-Bjergaard, Stig

    2015-07-07

    Electromembrane extraction (EME) and liquid-phase microextraction (LPME) were combined in a single step for the first time to realize simultaneous and clear group separation of basic and acidic drugs. Using 2-nitrophenyl octyl ether as the supported liquid membrane (SLM) for EME and dihexyl ether as the SLM for LPME, basic and acidic drugs were extracted and separated simultaneously from a low pH sample by EME and LPME, respectively. After 15 min of extraction, basic drugs (citalopram and sertraline) were exhaustively extracted, whereas the recoveries for acidic drugs (ketoprofen and ibuprofen) were in the range of 76%-86%. Longer extraction time provided higher recoveries for the acidic drugs, but this somewhat deteriorated the group separation. Matrices effects from the coexisting acidic drugs/basic drugs were tested, and we observed that simultaneous EME/LPME was not affected by coexisting drugs at high concentration. This approach was further investigated from human plasma. Extraction recoveries were strongly dependent on dilution of plasma with buffer and on extraction time. Finally, this simultaneous EME/LPME approach was evaluated in combination with liquid chromatography (LC)-MS. The linearity ranges for the basic and acidic drugs were 10-600 ng/mL and 1-60 μg/mL, respectively, with R(2) > 0.997 for all analytes. The repeatability at three different levels for all analytes was less than 15%. The limits of quantification (LOQ, S/N = 10) were found to be 4.0-6.3 ng/mL and 0.6-0.9 μg/mL for basic and acidic drugs, respectively. Simultaneous EME/LPME enabled efficient group separation of basic and acidic analytes under optimum experimental conditions for both EME and LPME.

  19. 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.

  20. Micellar liquid chromatography

    NASA Astrophysics Data System (ADS)

    Basova, Elena M.; Ivanov, Vadim M.; Shpigun, Oleg A.

    1999-12-01

    Background and possibilities of practical applications of micellar liquid chromatography (MLC) are considered. Various retention models in MLC, the effects of the nature and concentration of surfactants and organic modifiers, pH, temperature and ionic strength on the MLC efficiency and selectivity are discussed. The advantages and limitations of MLC are demonstrated. The performance of MLC is critically evaluated in relationship to the reversed-phase HPLC and ion-pair chromatography. The potential of application of MLC for the analysis of pharmaceuticals including that in biological fluids and separation of inorganic anions, transition metal cations, metal chelates and heteropoly compounds is described. The bibliography includes 146 references.

  1. Principles of Liquid Chromatography

    NASA Astrophysics Data System (ADS)

    Bakalyar, Stephen R.

    This article reviews the basic principles of high performance liquid chromatography (HPLC). The introductory section provides an overview of the HPLC technique, placing it in historical context and discussing the elementary facts of the separation mechanism. The next section discusses the nature of resolution, describing the two principal aspects, zone center separation and zone spreading. The third section takes a detailed look at how HPLC is used in practice to achieve a separation. It discusses the three key variables that need to be adjusted: retention, efficiency, and selectivity. A fourth section is concerned with various relationships of practical importance: flow rate, temperature, and pressure. A final section discusses future trends in HPLC.

  2. 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.

  3. 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.

  4. 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.

  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. 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)

  7. Biorecovered precious metals from industrial wastes: single-step conversion of a mixed metal liquid waste to a bioinorganic catalyst with environmental application.

    PubMed

    Mabbett, Amanda N; Sanyahumbi, Douglas; Yong, Ping; Macaskie, Lynne E

    2006-02-01

    The complete and continuous reduction of 1 mM Cr(VI) to Cr(III) was achieved in a flow-through reactor using a novel bioinorganic catalyst ("MM-bio-Pd(0)"), which was produced by single-step reduction of platinum group metals (PGM) from industrial waste solution onto biomass of Desulfovibrio desulfuricans ATCC 29577. Two flow-through reactor systems were compared using both "MM-bioPd(0)" and chemically reduced Pd(0). Reactors containing the latter removed Cr(VI) for 1 week only at the expense of formate as the electron donor, whereas the former gave complete Cr(VI) removal for 3 months of continuous operation. Mass balance analysis showed 100% reduction of Cr(VI) to soluble Cr(III) in the bioreactor exit solution. With the use of electron paramagnetic resonance (EPR) no intermediate Cr(V) species could be detected. Pd(0) was biodeposited similarly using Escherichia coliMC4100 and "bio-Pd(0)". The latter was used to recover Pd(II) from two acidic industrial waste leachates to generate two types of "MM-bio-Pd(0)": "SI-bio-Pd(0)" and "SII-bio-Pd(0)", respectively. The biomaterial composition was comparable in both cases, and the catalytic activity was related inversely to the amount of chloride in the waste leachate from which it was derived.

  8. CATALYST ACTIVITY MAINTENANCE FOR THE LIQUID PHASE SYNTHESIS GAS-TO-DIMETHYL ETHER PROCESS PART II: DEVELOPMENT OF ALUMINUM PHOSPHATE AS THE DEHYDRATION CATALYST FOR THE SINGLE-STEP LIQUID PHASE SYNGAS-TO-DME PROCESS

    SciTech Connect

    Xiang-Dong Peng

    2002-05-01

    At the heart of the single-step liquid phase syngas-to-DME process (LPDME{trademark}) is a catalyst system that can be active as well as stable. In the Alternative Fuels I program, a dual-catalyst system containing a Cu-based commercial methanol synthesis catalyst (BASF S3-86) and a commercial dehydration material ({gamma}-alumina) was demonstrated. It provided the productivity and selectivity expected from the LPDME process. However, the catalyst system deactivated too rapidly to warrant a viable commercial process [1]. The mechanistic investigation in the early part of the DOE's Alternative Fuels II program revealed that the accelerated catalyst deactivation under LPDME conditions is due to detrimental interaction between the methanol synthesis catalyst and methanol dehydration catalyst [2,3]. The interaction was attributed to migration of Cu- and/or Zn-containing species from the synthesis catalyst to the dehydration catalyst. Identification of a dehydration catalyst that did not lead to this detrimental interaction while retaining adequate dehydration activity was elusive. Twenty-nine different dehydration materials were tested, but none showed the desired performance [2]. The search came to a turning point when aluminum phosphate was tested. This amorphous material is prepared by precipitating a solution containing Al(NO{sub 3}){sub 3} and H{sub 3}PO{sub 4} with NH{sub 4}OH, followed by washing, drying and calcination. The aluminum phosphate catalyst has adequate dehydration activity and good stability. It can co-exist with the Cu-based methanol synthesis catalyst without negatively affecting the latter catalyst's stability. This report documents the details of the development of this catalyst. These include initial leads, efforts in improving activity and stability, investigation and development of the best preparation parameters and procedures, mechanistic understanding and resulting preparation guidelines, and the accomplishments of this work.

  9. Low thermal mass liquid chromatography.

    PubMed

    Gu, Binghe; Cortes, Hernan; Luong, Jim; Pursch, Matthias; Eckerle, Patric; Mustacich, Robert

    2009-02-15

    A novel technique, low thermal mass liquid chromatography (LTMLC), is introduced in this study. The use of an LTM assembly that utilizes the principle of resistive wire heating and a temperature sensor to accurately deliver unprecedented heating (up to 1800 degrees C/min) or cooling (100 to approximately 200 degrees C/min) rates is reported. With the use of packed microcolumns (<0.5 mm i.d.), essentially instantaneous heat transfer from the assembly to the mobile phase was obtained. A systematic investigation was conducted to study the performance of the LTMLC technique. Both isocratic and gradient mobile phase conditions were used. For temperature control, isothermal, temperature-increasing, and temperature-decreasing gradients were applied. Three model mixtures, two of which containing neutral and acidic analytes and the other containing neutral, acidic, and basic analytes, were used to study the effect of temperature on elution time, resolution, column efficiency, and selectivity. It was found that the LTMLC experimental setup delivered reliable temperature control, as evidenced by linear van't Hoff plots for neutral and acidic compounds. The effect of temperature on the elution of basic analytes yielded nonlinear van't Hoff plots, explaining the dramatic selectivity changes observed for bases with changes in column temperature. Column efficiency generally increased with the increase in column temperature in the range of 25 to approximately 75 degrees C and decreased in the range of 75 to approximately 150 degrees C at a fixed column flow rate (3 microL/min), when extra column band broadening was taken into account. The increase in efficiency upon the increase in column temperature in the low temperature range was mainly due to the decreased mass transfer term resulting from increased analyte diffusivity. However, under even higher temperatures, the longitudinal diffusion dominated band broadening, explaining the decrease in column efficiency upon a further

  10. Liquid chromatography detection unit, system, and method

    DOEpatents

    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.

  11. 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.

  12. 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)

  13. High Performance Liquid Chromatography/Video Fluorometry. Part I. Instrumentation.

    DTIC Science & Technology

    1981-09-30

    High Performance Liquid Chromatography /Video...PERIOD COVERED High Performance Liquid Chromatography /Video .. / Fluorometry. Part I. Instrumentation. . Interim/ echnicaliepart,. 6. PERFORMING ORG...34Entered SECURITY CLASSIFICATION OF THIS OlAGE (When Data Entered) II1| III I I I I E I II ... .. High Performance Liquid Chromatography

  14. Recent development of ionic liquid stationary phases for liquid chromatography.

    PubMed

    Shi, Xianzhe; Qiao, Lizhen; Xu, Guowang

    2015-11-13

    Based on their particular physicochemical characteristics, ionic liquids have been widely applied in many fields of analytical chemistry. Many types of ionic liquids were immobilized on a support like silica or monolith as stationary phases for liquid chromatography. Moreover, different approaches were developed to bond covalently ionic liquids onto the supporting materials. The obtained ionic liquid stationary phases show multi-mode mechanism including hydrophobic, hydrophilic, hydrogen bond, anion exchange, π-π, and dipole-dipole interactions. Therefore, they could be used in different chromatographic modes including ion-exchange, RPLC, NPLC and HILIC to separate various classes of compounds. This review mainly summarizes the immobilized patterns and types of ionic liquid stationary phases, their retention mechanisms and applications in the recent five years.

  15. High perfomance liquid chromatography in pharmaceutical analyses.

    PubMed

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

    2004-05-01

    In testing the pre-sale procedure the marketing of drugs and their control in the last ten years, high performance liquid chromatography replaced numerous spectroscopic methods and gas chromatography in the quantitative and qualitative analysis. In the first period of HPLC application it was thought that it would become a complementary method of gas chromatography, however, today it has nearly completely replaced gas chromatography in pharmaceutical analysis. The application of the liquid mobile phase with the possibility of transformation of mobilized polarity during chromatography and all other modifications of mobile phase depending upon the characteristics of substance which are being tested, is a great advantage in the process of separation in comparison to other methods. The greater choice of stationary phase is the next factor which enables realization of good separation. The separation line is connected to specific and sensitive detector systems, spectrafluorimeter, diode detector, electrochemical detector as other hyphernated systems HPLC-MS and HPLC-NMR, are the basic elements on which is based such wide and effective application of the HPLC method. The purpose high performance liquid chromatography (HPLC) analysis of any drugs is to confirm the identity of a drug and provide quantitative results and also to monitor the progress of the therapy of a disease.1) Measuring presented on the Fig. 1. is chromatogram obtained for the plasma of depressed patients 12 h before oral administration of dexamethasone. It may also be used to further our understanding of the normal and disease process in the human body trough biomedical and therapeutically research during investigation before of the drugs registration. The analyses of drugs and metabolites in biological fluids, particularly plasma, serum or urine is one of the most demanding but one of the most common uses of high performance of liquid chromatography. Blood, plasma or serum contains numerous endogenous

  16. Recent applications of hydrophilic interaction liquid chromatography in pharmaceutical analysis.

    PubMed

    Zhang, Qian; Yang, Feng-Qing; Ge, Liya; Hu, Yuan-Jia; Xia, Zhi-Ning

    2017-01-01

    Hydrophilic interaction liquid chromatography, an alternative liquid chromatography mode, is of particular interest in separating hydrophilic and polar ionic compounds. Compared with traditional liquid chromatography techniques, hydrophilic interaction liquid chromatography offers specific advantages mainly including: (1) relatively green and water-soluble mobile phase composition, which enhances the solubility of hydrophilic and polar ionic compounds; (2) no need for ion-pairing reagents and high content of organic solvent, which benefits mass spectrometry detection; (3) high orthogonality to reverse-phase liquid chromatography, well adapted to two-dimensional liquid chromatography for complicated samples. Therefore, hydrophilic interaction liquid chromatography has been rapidly developed in many areas over the past decades. This review summarizes the recent progress (from 2012 to July 2016) of hydrophilic interaction liquid chromatography in pharmaceutical analysis, with the focus on detecting chemical drugs in various matrices, charactering active compounds of natural products and assessing biotherapeutics through typical structure unit. Moreover, the retention mechanism and behavior of analytes in hydrophilic interaction liquid chromatography as well as some novel hydrophilic interaction liquid chromatography columns used for pharmaceutical analysis are also described.

  17. 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

  18. 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.

  19. High Performance Liquid Chromatography/Video Fluorometry. Part II. Applications.

    DTIC Science & Technology

    1981-09-30

    HIGH PERFORMANCE LIQUID CHROMATOGRAPHY /VIDEO FLUOROMETRY. PART...REP«T_N&:-ŗ/ High Performance Liquid Chromatography /Video Fluorometry» Part II. Applications« by | Dennis C./Shelly* Michael P./Vogarty and...Data EnlirtdJ REPORT DOCUMENTATION PAGE t. REPORT NUMBER 2 GOVT ACCESSION NO 4. T1TI.F (and Submit) lP-^fffsyva High Performance Liquid Chromatography

  20. Separation of biological proteins by liquid chromatography

    PubMed Central

    Ali, Imran; Aboul-Enein, Hassan Y.; Singh, Prashant; Singh, Rakesh; Sharma, Bhavtosh

    2010-01-01

    After the success of human genome project, proteome is a new emerging field of biochemistry as it provides the knowledge of enzymes (proteins) interactions with different body organs and medicines administrated into human body. Therefore, the study of proteomics is very important for the development of new and effective drugs to control many lethal diseases. In proteomics study, analyses of proteome is essential and significant from the pathological point of views, i.e., in several serious diseases such as cancer, Alzheimer’s disease and aging, heart diseases and also for plant biology. The separation and identification of proteomics is a challenging job due to their complex structures and closely related physico-chemical behaviors. However, the recent advances in liquid chromatography make this job easy. Various kinds of liquid chromatography, along with different detectors and optimization strategies, have been discussed in this article. Besides, attempts have been made to include chirality concept in proteomics for understanding mechanism and medication of various disease controlled by different body proteins. PMID:23960722

  1. Determination of formaldehyde in beverages using microwave-assisted derivatization and ionic liquid-based dispersive liquid-liquid microextraction followed by high-performance liquid chromatography.

    PubMed

    Xu, Xu; Su, Rui; Zhao, Xin; Liu, Zhuang; Li, Dan; Li, Xueyuan; Zhang, Hanqi; Wang, Ziming

    2011-10-15

    A simple method based on simultaneous microwave-assisted derivatization and ionic liquid-based dispersive liquid-liquid microextraction (IL-based DLLME) is proposed for the derivatization, extraction and preconcentration of formaldehyde in beverage samples prior to the determination by high-performance liquid chromatography (HPLC). Formaldehyde was in situ derivatized with 2,4-dinitrophenylhydrazine (DNPH) and simultaneously extracted and preconcentrated by using microwave-assisted derivatization and IL-based DLLME in a single step. Several experimental parameters, including type and volume of extraction solvent, type and volume of disperser, microwave power and irradiation time, volume of DNPH, pH of sample solution, and ionic strength were evaluated. When the microwave power was 120 W, formaldehyde could be derivatized and extracted simultaneously only within 90 s. Under optimal experimental conditions, good linearity was observed in the range of 0.5-50 ng/mL with the correlation coefficient of 0.9965, and the limit of detection was 0.12 ng/mL. The proposed method was applied to the analysis of different beverage samples, and the recoveries of formaldehyde obtained were in the range of 84.9-95.1% with the relative standard deviations lower than 8.4%. The results showed that the proposed method was a rapid, convenient and feasible method for the determination of formaldehyde in beverage samples.

  2. 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.

  3. 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.

  4. Pharmacokinetic analysis of levo-tetrahydropalmatine in rabbit plasma by rapid sample preparation and liquid chromatography-tandem mass spectrometry.

    PubMed

    Tran, Son Cao; Duc, Nguyen Dinh; Tung, Nguyen-Thach

    2016-01-01

    A rapid extraction method was developed and validated for levo-tetrahydropalmatine (l-THP) determination in rabbit plasma by liquid chromatography tandem-mass spectrometry (LC-MS/MS). The sample preparation included a single-step acetonitrile extraction and salting out liquid-liquid partitioning from the water in plasma with MgSO4. Berberine was used as internal standard. The mass spectrometry source was negative electrospray ionization. The method showed good performance in the concentration range from 5 to 200ngmL(-1). The limit of quantification (LOQ) was 1ngmL(-1). The method was successfully applied to a pharmacokinetic study in rabbit comparing the two drug formulation of l-THP including the raw material and the self-microemulsifying drug delivery system pellet.

  5. 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)

  6. A generalized theory of chromatography and multistep liquid extraction

    NASA Astrophysics Data System (ADS)

    Chizhkov, V. P.; Boitsov, V. N.

    2017-03-01

    A generalized theory of chromatography and multistep liquid extraction is developed. The principles of highly efficient processes for fine preparative separation of binary mixture components on a fixed sorbent layer are discussed.

  7. 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.

  8. 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 ...

  9. 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)

  10. 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.

  11. 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

  12. 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…

  13. 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…

  14. 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…

  15. 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...

  16. 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)

  17. 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)

  18. 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.

  19. 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…

  20. Analysis of Free Fatty Acids on the Fingertips by High Performance Liquid Chromatography.

    DTIC Science & Technology

    1978-12-20

    This investigation studied the efficiency of high performance liquid chromatography in the determination of free fatty acids present on the...utilized to eliminate the microbial contamination. The high performance liquid chromatography provided excellent separation of skin fatty acids for

  1. Determination of a Jet Fuel Metal Deactivator by High Performance Liquid Chromatography

    DTIC Science & Technology

    1983-06-01

    HIGH PERFORMANCE LIQUID CHROMATOGRAPHY Paul C. Hayes, Jr. Fuels Branch...SUPPLEMENTARY NOTES 19. KEY WORDS (Continue on reverse side if necessary and identify by block number) High Performance Liquid Chromatography absorbance...SYMBOL HPLC High Performance Liquid Chromatography P-4 jet propulsion fuel, wide-boiling range, conforming to MIL-T-5624L MDA metal deactivator,

  2. Determination of Stabiliser Contents in Advanced Gun Propellants by Reverse Phase High Performance Liquid Chromatography

    DTIC Science & Technology

    1994-03-01

    HIGH PERFORMANCE LIQUID CHROMATOGRAPHY N"m A.R. TURNER AND A. WHITE...TO biEPROOU.; AND SELL THIS REPORT Determination of Stabiliser Contents in Advanced Gun Propellants by Reverse Phase High Performance Liquid Chromatography A.R...8217/......... .. Availability Cooes Dist Avaiardlo A-i Determination of Stabiliser Contents in Advanced Gun Propellants by Reverse Phase High Performance Liquid Chromatography

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 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.

  14. 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%.

  15. Amino acids as chiral selectors in enantioresolution by liquid chromatography.

    PubMed

    Bhushan, Ravi; Dixit, Shuchi

    2012-08-01

    Amino acids are unique in terms of their structural features and multidimensional uses. With their simple structures and the ready availability of both enantiomers, amino acids not only serve as a chiral pool for synthesis but also provide an inexpensive pool for resolution studies. There has been no attempt to review the application of amino acids as chiral selectors for chromatographic enantioresolution of pharmaceuticals and other compounds. The present paper deals with application of l-amino acids and complexes of l-amino acids with a metal ion, particularly Cu(II), as an impregnating reagent in thin-layer chromatography or as a chiral ligand exchange reagent or a chiral mobile phase additive in both thin-layer chromatography and high-performance liquid chromatography. Enantiomeric resolution of β-blockers, nonsteroidal anti-inflammatories, amino acids (and their derivatives) and certain other compounds is discussed.

  16. 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

  17. Evaluation of surface excess isotherms in liquid chromatography.

    PubMed

    Vajda, Péter; Felinger, Attila; Guiochon, Georges

    2013-05-24

    Methods are proposed to calculate surface excess isotherms and to use them to derive adsorption isotherms in liquid chromatography. The consequences of these methods are discussed. The excess isotherm of isopropyl alcohol from its aqueous solutions on a C18 adsorbent was obtained using the minor disturbance method. The slope of the inflection tangent of the excess isotherm provides the position of the plane separating the adsorbed layer and the bulk phase, from which the adsorption isotherm was derived. At low concentrations of isopropyl alcohol, frontal analysis was used to derive the adsorption isotherm on the same adsorbent using an independent method. The isotherm was thus derived from both frontal analysis data and the minor disturbance method. The results obtained are compared. Our results show that the use of the same concentration unit for the calculation and the representation of the data is the only correct way to calculate the excess isotherms in practical applications of liquid chromatography.

  18. Nano-liquid chromatography applied to enantiomers separation.

    PubMed

    Fanali, Salvatore

    2017-02-24

    This paper presents the state of the art concerning the separation of chiral compounds by means of nano-liquid chromatography (nano-LC). The enantiomers' separation and determination are a subject of fundamental importance in various application fields such as pharmaceutical industry, biomedicine, food, agrochemical etc. Nano-LC is a miniaturized chromatographic technique offering some advantages over conventional ones such as low consumption of mobile phase, sample volume and amount of chiral stationary phase, reduced costs etc. This is reported in the first part of the paper illustrating the features of the nano-LC. In addition, chiral resolution methods are briefly illustrated. Some chiral selectors, used in high-performance liquid chromatography have also been applied in nano-LC including cyclodextrins, glycopeptide antibiotics, modified polysaccharides etc. This is discussed in the second part of the review. Finally some examples of the applications available in literature are reported.

  19. Analysis of selected ionic liquid cations by ion exchange chromatography and reversed-phase high performance liquid chromatography.

    PubMed

    Stepnowski, Piotr; Mrozik, Wojciech

    2005-02-01

    The chromatographic behavior of 8 ionic liquids - 7 homologues of 1-alkyl-3-methylimidazolium and 4-methyl-N-butylpyridinium - has been investigated with a strong cation exchange adsorbent. In particular, the dependence of the retention properties of these solutes on mobile phase composition, pH, and buffer concentration was evaluated with the aim of optimizing and improving the selectivity and retention of solute separation. While using the SCX stationary phase, several interactions occurred with varying strengths, depending on the mobile phase composition. Cation exchange, nonspecific hydrophobic interactions, and adsorption chromatography behavior were observed. Reversed phase chromatography occurred at low concentrations of acetonitrile, electrostatic and adsorption interactions at higher organic modifier concentrations. Elevated buffer concentrations lowered the retention factors without affecting the selectivity of ionic liquids. Obtained results were further compared to the chromatographic behaviour of ionic liquids in the reversed phase system. All analyzed ionic liquids follow reversed-phase behavior while being separated. Much lower selectivity in the range of highly hydrophilic compounds is obtained. This suggests preferred use of ion chromatography for separation and analysis of compounds below 4 carbon atoms in the alkyl side chain.

  20. Determination of aminocresol isomers by high-speed liquid chromatography.

    PubMed

    Sakurai, H; Kito, M

    Aminocresol isomers (4-hydroxy-m-toluidine [II], 3-hydroxy-p-toluidine [II], 2-hydroxy-p-toluidine [III]) and p-aminophenol have been separated and determined by a high-speed liquid Chromatographie method. Since this method is applicable in aqueous media, it was used to investigate the suitability of a haemin-cysteine system as a model for the cytochrome P-450 mono-oxygenase system, by determination of the [I], [II], [III] and p-aminophenol formed.

  1. Fiber Bragg grating photoacoustic detector for liquid chromatography.

    PubMed

    Yang, Qingxin; Loock, Hans-Peter; Kozin, Igor; Pedersen, David

    2008-11-01

    Fiber Bragg Gratings (FBGs) are known to be sensitive acoustic transducers and have previously been used for the photoacoustic detection of small solid samples. Here, we demonstrate the use of an FBG as an on-line detector for liquid chromatography. The FBG was inserted into a silica capillary and the photoacoustic response from the effluent was generated by a 10 ns pulsed laser. The acoustic pulse was quantified by the FBG through a characteristic change in the reflection spectrum. Good repeatability and linear response were obtained over three orders of magnitude (R(2) > 0.99), and the limit of detection of Coumarin 440 was determined to be 5 microM. The technique was successfully coupled to high performance liquid chromatography and applied to on-line analysis of a three-compound solution. Photoacoustic detection in liquid chromatography using FBGs is a label-free method, which can be applied to the detection of any chromogenic compound irrespective of its fluorogenic properties. It is a simple, inexpensive, and inherently micron-sized technique, insensitive to electromagnetic interference.

  2. Carbon nanotubes-A resin for electrochemically modulated liquid chromatography.

    PubMed

    Brammen, Markus; Fraga-García, Paula; Berensmeier, Sonja

    2017-03-01

    Electrochemically modulated liquid chromatography is a special form of ion exchange chromatography in which the separation process is controlled by applying an electric potential to the stationary phase. This form of chromatography has so far only been applied in research studies. The present study shows that multiwalled carbon nanotubes are an effective resin material for an electrochemically modulated chromatography process. The experiments are carried out in a newly designed column that enables the packing of nanomaterials. We investigate the influence of the applied potential on the retention and elution of maleic acid, determine the dynamic binding capacity, and calculate the utilization degree of the electrical charge in the adsorption process. Moreover, the stability of the resin and the membrane over more than 200 working hours are presented. In addition to the stability, their sturdiness and inexpensive price are important qualities that make multiwalled carbon nanotubes interesting for application as the stationary phase in an electrochemically driven process. The investigated chromatography technique represents a promising separation process for future applications as a preparative step in biotechnology as well as other life science fields.

  3. Facile preparation of a stable and functionalizable hybrid monolith via ring-opening polymerization for capillary liquid chromatography.

    PubMed

    Lin, Hui; Ou, Junjie; Tang, Shouwan; Zhang, Zhenbin; Dong, Jing; Liu, Zhongshan; Zou, Hanfa

    2013-08-02

    An organic-inorganic hybrid monolith was prepared by a single-step ring-opening polymerization of octaglycidyldimethylsilyl polyhedral oligomeric silsesquioxane (POSS) with poly(ethylenimine) (PEI). The obtained hybrid monoliths possessed high ordered 3D skeletal microstructure with dual retention mechanism that exhibits reversed-phase (RP) mechanism under polar mobile phase and hydrophilic-interaction liquid chromatography (HILIC) retention mechanism under less polar mobile phase. The high column efficiencies of 110,000N/m can be achieved for separation of alkylbenzenes in capillary reversed-phase liquid chromatography (cLC). Due to the robust property of hybrid monolith and the rich primary and secondary amino groups on its surface, the resulting hybrid monolith was easily modified with γ-gluconolactone and physically coated with cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC), respectively. The former was successfully applied for HILIC separation of neutral, basic and acidic polar compounds as well as small peptides, and the latter for enantioseparation of racemates in cLC. The high column efficiencies were achieved in all of those separations. These results demonstrated that the hybrid monolith (POSS-PEI) possessed high stability and good surface tailorbility, potentially being applied for other research fields.

  4. Thermal expansion pump for capillary high-performance liquid chromatography.

    PubMed

    Tao, Qian; Wu, Qian; Zhang, Xiangmin

    2010-02-01

    A thermal expansion pump (TEP) based on a principle of liquid thermal expansion for capillary high-performance liquid chromatography has been developed. The novel pump is capable of generating a continuous flow at high pressure for constant and stable delivery of binary solvents from nanoliters to microliters per minute without splitting. Theoretical equations for controlling fluidic output of this pump have been established and validated by a series of experiments. Factors affecting flow rate, such as density discrepancy, liquid compressibility, and mass loss in output, were taken into account. An assembly of the pump system employing two groups of thermal expansion pumps (TEPs) working in turns were fabricated, and a controlling strategy for the pump system to maintain a continuous delivery without pressure fluctuation even at switching points was also developed. Both isocratic and gradients of binary solvent delivery by the TEPs were performed. Reproducibility and standard deviation at different flow rates were determined. A capillary high-performance liquid chromatography (micro-HPLC) system consisting of the TEPs, an injection valve, a homemade packed capillary column (20 cm x 100 microm i.d. with 5 microm C18), and a laser-induced fluorescence detector was set up, and sample separations were carried out. Results of RSD = 4% for flow and RSD = 2% for retention times at 500 nL/min were achieved. Such a pump system has almost no moving parts except for the solvent switches. Its overall costs of manufacture and running are very low. It is proven that the TEPs system has great potential and competitive capabilities in capillary liquid chromatography.

  5. Comprehensive two-dimensional liquid chromatography: ion chromatography × reversed-phase liquid chromatography for separation of low-molar-mass organic acids.

    PubMed

    Brudin, Stella S; Shellie, Robert A; Haddad, Paul R; Schoenmakers, Peter J

    2010-10-22

    In the work presented here a novel approach to comprehensive two-dimensional liquid chromatography is evaluated. Ion chromatography is chosen for the first-dimension separation and reversed-phase liquid chromatography is chosen for the second-dimension separation mode. The coupling of these modes is made possible by neutralising the first-dimension effluent, containing KOH, prior to transfer to the second-dimension reversed-phase column. A test mixture of 24 low-molar-mass organic acids is used for optimisation of the system. Three food and beverage samples were analysed in order to evaluate the developed methodology, the resulting two-dimensional separation is near-orthogonal, the set-up is simple and all instrumental components are available commercially. The method proved to be robust and suitable for the analysis of wine, orange juice and yogurt.

  6. MEMS Liquid and Gas Chromatography for Miniaturized Planetary In Situ Instruments

    NASA Astrophysics Data System (ADS)

    Kidd, R. D.; Bae, B.; Willis, P. A.; Noell, A. C.; Scianmarello, N.; Tai, Y.-C.

    2016-10-01

    Micro-Electro-Mechanical Systems (MEMS) technology to reduce the size, mass and power of the three classical chromatographic technologies: gas chromatography (GC), capillary electrophoresis (CE) and high performance liquid chromatography (HPLC).

  7. Simultaneous determination of buprenorphine, norbuprenorphine and naloxone in human plasma by liquid chromatography/tandem mass spectrometry.

    PubMed

    Liu, Yongzhen; Li, Xiaohua; Xu, Allan; Nasser, Azmi F; Heidbreder, Christian

    2016-02-20

    A simple, sensitive and rapid liquid chromatography/electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method was developed and validated for simultaneous quantification of naloxone, buprenorphine and its metabolite norbuprenorphine in human plasma. Human plasma samples were extracted using a single step liquid-liquid extraction, and then separated on an Imtakt Unison UK-C18 column (2.1×50mm, 3μm) using alkaline mobile phases with gradient elution. All of the analytes were detected in positive ion mode using multiple reaction monitoring (MRM). The method was validated and the specificity, linearity, lower limit of quantitation, precision, accuracy, recoveries and stability were determined. The linear range was 20-10000pg/mL for buprenorphine and norbuprenorphine; and 1-500pg/mL for naloxone. The correlation coefficient (R(2)) values for all three analytes were ≥0.995. The precision and accuracy for intra-day and inter-day were <11.0%. The recoveries were >63% and matrix effects were tracked by the deuterated internal standards (IS) with the IS-normalized matrix factor ranging from 0.96 to 1.33 for all three analytes. The validated method was successfully applied in a clinical pharmacokinetic study with low dose administration of sublingual buprenorphine and naloxone.

  8. 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.

  9. Control of column temperature in reversed-phase liquid chromatography.

    PubMed

    Wolcott, R G; Dolan, J W; Snyder, L R; Bakalyar, S R; Arnold, M A; Nichols, J A

    2000-02-11

    When separations by reversed-phase liquid chromatography (RP-LC) are carried out at temperatures other than ambient, resulting retention times and bandwidths can depend on the equipment used. As a result, an RP-LC separation that is adequate when carried out on one LC system may prove inadequate when the separation is repeated on a second system. In the present study, various temperature-related problems which can result in a failure of method transfer for non-ambient RP-LC methods were examined. Means for correcting for such effects and thereby ensuring method transferability are described.

  10. 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.

  11. Training software for high-performance liquid chromatography.

    PubMed

    Reijenga, J C

    2000-12-01

    A computer simulation program of reversed-phase high-performance liquid chromatography was developed for training purposes. Experimental retention values of 75 organic compounds on a reversed-phase column at four different percentages of organic modifiers were reduced to a two-parameter retention model with the modifier content as variable. Modifiers used were acetonitrile, methanol and tetrahydrofuran. Isocratic and programmed solvent composition were included together with the usual experimental parameters available in modern HPLC equipment, such as UV diode array and refractive index detection. Instrument specifications were made variable within wide ranges. Detailed dispersion data were made available as tabulated output.

  12. Identification of mycobacteria by high-performance liquid chromatography.

    PubMed Central

    Butler, W R; Jost, K C; Kilburn, J O

    1991-01-01

    Mycolic acids extracted from saponified mycobacterial cells were examined as p-bromophenacyl esters by high-performance liquid chromatography (HPLC). Standard HPLC patterns were developed for species of Mycobacterium by examination of strains from culture collections and other well-characterized isolates. Relative retention times of peaks and peak height comparisons were used to develop a differentiation scheme that was 98% accurate for the species examined. A rapid, cost-effective HPLC method which offers an alternative approach to the identification of mycobacteria is described. PMID:1774251

  13. 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.

  14. Determination of Selected Colored Smokes on Glass Fiber Discs by High Performance Liquid Chromatography (HPLC)

    DTIC Science & Technology

    1991-05-01

    High Performance Liquid Chromatography (HPLC) 12. PERSONAL AUTHOR(S) F F_ n.ipl’prifl. Alan R...GROUP SUB-GROUP High Performance Liquid Chromatography (HPLC), Analytical IMethod, 1,4-diamino-2,3-dihydroanthraquinone, 2-(2 - _ quinolinyl)-1,3...weights, low vapor pressures and low thermal stability. High performance liquid chromatography (HPLC) appears to be the analytical method of choice

  15. Vapor Pressure Determination of VM Using the Denunder-Liquid Chromatography-Mass Spectrometry Technique

    DTIC Science & Technology

    2015-01-01

    LIQUID CHROMATOGRAPHY –MASS SPECTROMETRY TECHNIQUE ECBC-TR-1278 Amanda L. Jenkins ASK, INC. Hebron, MD 21830-1224 Eric J. Bruni LEIDOS, INC...2012 – Sep 2012 4. TITLE AND SUBTITLE Vapor Pressure Determination of VM Using the Denuder–Liquid Chromatography –Mass Spectrometry Technique 5a...a novel, denuder-based liquid chromatography –mass spectrometry (LC–MS) approach designed specifically for low- volatility and thermally unstable

  16. Analysis of beechwood creosote by gas chromatography-mass spectrometry and high-performance liquid chromatography.

    PubMed

    Ogata, N; Baba, T

    1989-12-01

    Compounds in beechwood creosote were analyzed by gas chromatography-mass spectrometry, and 22 major constituents were identified. Of these, 19 were phenolic compounds, i. e., guaiacol, phenol, two cresol isomers, four methylguaiacol (creosol) isomers, six xylenol isomers, two trimethylphenol isomers, 4-ethylguaiacol, 4-ethyl-5-methylguaiacol, and 4-propylguaiacol. The remaining three were hitherto unpredicted five-membered ring compounds, i. e., 3-methyl-2-hydroxy-2-cyclopenten-1-one, 3,5-dimethyl-2-hydroxy-2-cyclopenten-1-one, and 3-ethyl-2-hydroxy-2-cyclopenten-1-one. The relative quantities of these compounds were also compared with those obtained by high-resolution high-performance liquid chromatography. This report probably represents the first extensive analysis of beechwood creosote.

  17. Gas chromatography and high-performance liquid chromatography of natural steroids.

    PubMed

    Shimada, K; Mitamura, K; Higashi, T

    2001-11-23

    This review article underlines the importance of gas chromatography (GC), high-performance liquid chromatography (HPLC) and their hyphenated techniques using mass spectrometry (MS) for the determination of natural steroids, especially in human biological fluids. Steroids are divided into eight categories based on their structures and functions, and recent references using the above methodologies for the analysis of these steroids are cited. GC and GC-MS are commonly used for the determination of volatile steroids. Although HPLC is a widely used analytical method for the determination of steroids including the conjugated type in biological fluids, LC-MS is considered to be the most promising one for this purpose because of its sensitivity, specificity and versatility.

  18. Hydrazine Determination in Sludge Samples by High Performance Liquid Chromatography

    SciTech Connect

    G. Elias; G. A. Park

    2006-02-01

    A high-performance liquid chromatographic method using ultraviolet (UV) detection was developed to detect and quantify hydrazine in a variety of environmental matrices. The method was developed primarily for sludge samples, but it is also applicable to soil and water samples. The hydrazine in the matrices was derivatized to their hydrazones with benzaldehyde. The derivatized hydrazones were separated using high performance liquid chromatography (HPLC) with a reversed-phase C-18 column in an isocratic mode with methanol-water (95:5, v/v), and detected with UV detection at 313 nm. The detection limit (25 ml) for the new analytical method is 0.0067 mg ml-1of hydrazine. Hydrazine showed low recovery in soil samples because components in soil oxidized hydrazine. Sludge samples that contained relatively high soil content also showed lower recovery. The technique is relatively simple and cost-effective, and is applicable for hydrazine analysis in different environmental matrices.

  19. Single-Step Purification of Ovalbumin from Egg White Using Aqueous Biphasic Systems.

    PubMed

    Pereira, Matheus M; Cruz, Rafaela A P; Almeida, Mafalda R; Lima, Álvaro S; Coutinho, João A P; Freire, Mara G

    2016-06-01

    The ability of aqueous biphasic systems (ABS) composed of polyethylene glycols of different molecular weights (PEG 400, 600 and 1000) and buffered aqueous solutions of potassium citrate/citric acid (pH = 5.0 - 8.0) to selectively extract ovalbumin from egg white was here investigated. Phase diagrams, tie-lines and tie-line lengths were determined at 25ºC and the partitioning of ovalbumin in these systems was then evaluated. Aiming at optimizing the selective extraction of ovalbumin in the studied ABS, factors such as pH, PEG molecular weight and amount of the phase-forming components were initially investigated with pure commercial ovalbumin. In almost all ABS, it was observed a preferential partitioning of ovalbumin to the polymer-rich phase, with extraction efficiencies higher than 90%. The best ABS were then applied in the purification of ovalbumin from the real egg white matrix. In order to ascertain on the ovalbumin purity and yield, sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and size exclusion high performance liquid chromatography (SE-HPLC) analyses were conducted, confirming that the isolation/purification of ovalbumin from egg white was completely achieved in a single-step with a recovery yield of 65%. The results obtained show that polymer-salt-based ABS allow the selective extraction of ovalbumin from egg white with a simpler approach and better performance than previously reported. Finally, it is shown that ovalbumin can be completely recovered from the PEG-rich phase by an induced precipitation using an inexpensive and sustainable separation platform which can be easily applied on an industrial scale.

  20. Single-Step Purification of Ovalbumin from Egg White Using Aqueous Biphasic Systems

    PubMed Central

    Pereira, Matheus M.; Cruz, Rafaela A. P.; Almeida, Mafalda R.; Lima, Álvaro S.; Coutinho, João A. P.; Freire, Mara G.

    2016-01-01

    The ability of aqueous biphasic systems (ABS) composed of polyethylene glycols of different molecular weights (PEG 400, 600 and 1000) and buffered aqueous solutions of potassium citrate/citric acid (pH = 5.0 - 8.0) to selectively extract ovalbumin from egg white was here investigated. Phase diagrams, tie-lines and tie-line lengths were determined at 25ºC and the partitioning of ovalbumin in these systems was then evaluated. Aiming at optimizing the selective extraction of ovalbumin in the studied ABS, factors such as pH, PEG molecular weight and amount of the phase-forming components were initially investigated with pure commercial ovalbumin. In almost all ABS, it was observed a preferential partitioning of ovalbumin to the polymer-rich phase, with extraction efficiencies higher than 90%. The best ABS were then applied in the purification of ovalbumin from the real egg white matrix. In order to ascertain on the ovalbumin purity and yield, sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and size exclusion high performance liquid chromatography (SE-HPLC) analyses were conducted, confirming that the isolation/purification of ovalbumin from egg white was completely achieved in a single-step with a recovery yield of 65%. The results obtained show that polymer-salt-based ABS allow the selective extraction of ovalbumin from egg white with a simpler approach and better performance than previously reported. Finally, it is shown that ovalbumin can be completely recovered from the PEG-rich phase by an induced precipitation using an inexpensive and sustainable separation platform which can be easily applied on an industrial scale. PMID:27642253

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

    PubMed

    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.

  2. 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.

  3. 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.

  4. Liquid chromatography tandem mass spectrometry in the clinical laboratory.

    PubMed

    Adaway, Joanne E; Keevil, Brian G; Owen, Laura J

    2015-01-01

    Clinical laboratory medicine has seen the introduction and evolution of liquid chromatography tandem mass spectrometry in routine clinical laboratories over the last 10-15 years. There still exists a wide diversity of assays from very esoteric and highly specialist manual assays to more simplified kit-based assays. The technology is not static as manufacturers are continually making improvements. Mass spectrometry is now commonly used in several areas of diagnostics including therapeutic drug monitoring, toxicology, endocrinology, paediatrics and microbiology. Some of the most high throughput analyses or common analytes include vitamin D, immunosuppressant monitoring, androgen measurement and newborn screening. It also offers flexibility for the measurement of analytes in a variety of different matrices which would prove difficult with immunoassays. Unlike immunoassays or high-pressure liquid chromatography assays using ultraviolet or fluorescence detection, mass spectrometry offers better specificity and reduced interferences if attention is paid to potential isobaric compounds. Furthermore, multiplexing, which enables multiple analytes to be measured with the same volume of serum is advantageous, and the requirement for large sample volumes is decreasing as instrument sensitivity increases. There are many emerging applications in the literature. Using mass spectrometry to identify novel isoforms or modified peptides is possible as is quantification of proteins and peptides, with or without protein digests. Future developments by the manufacturers may also include mechanisms to improve the throughput of samples and strategies to decrease the level of skill required by the operators.

  5. 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.

  6. 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.

  7. 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.

  8. Comprehensive characterization of Stevia rebaudiana using two-dimensional reversed-phase liquid chromatography/hydrophilic interaction liquid chromatography.

    PubMed

    Fu, Qing; Guo, Zhimou; Zhang, Xiuli; Liu, Yanfang; Liang, Xinmiao

    2012-07-01

    Two-dimensional reversed-phase liquid chromatography/hydrophilic interaction liquid chromatography (2D-RPLC/HILIC) system was successfully applied for comprehensive characterization of steviol glycosides from Stevia rebaudiana. The experiments were performed in offline mode using an XCharge C18 column in first dimension and an XAmide column in second dimension. In first dimension, preliminary separation of Stevia aqueous extract was accomplished and 30 fractions were collected. Then fractions 1-20 were selected for further purification and 13 compounds with high purity were obtained in second dimension. Comprehensive characterization of these compounds was completed by determination of their retention time, accurate molecular weight, diagnostic fragmentation ions, and nuclear magnetic resonance spectroscopy. As a result, all nine known steviol glycosides, as well as other four steviol glycosides were fully purified. The result demonstrated that this procedure is an effective approach for the preparative separation and comprehensive characterization of steviol glycosides in Stevia. This 2D-RPLC/HILIC method will be a promising tool for the purification of low-abundance compounds from natural products.

  9. 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

    2015-07-03

    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.

  10. Fully automatable two-dimensional hydrophilic interaction liquid chromatography-reversed phase liquid chromatography with online tandem mass spectrometry for shotgun proteomics.

    PubMed

    Zhao, Yun; Kong, Ricky P W; Li, Guohui; Lam, Maggie P Y; Law, C H; Lee, Simon M Y; Lam, Herman C; Chu, Ivan K

    2012-07-01

    We have developed a fully automatable two-dimensional liquid chromatography platform for shotgun proteomics analyses based on the online coupling of hydrophilic interaction liquid chromatography (HILIC) - using a nonionic type of TSKgel Amide 80 at either pH 6.8 (neutral) or 2.7 (acidic) - with conventional low-pH reversed-phase chromatography. Online coupling of the neutral-pH HILIC and reversed phase chromatography systems outperformed the acidic HILIC-reversed phase chromatography combination, resulting in 18.4% (1914 versus 1617 nonredundant proteins) and 41.6% (12,989 versus 9172 unique peptides) increases in the number of identified peptides and proteins from duplicate analyses of Rat pheochromocytoma lysates. Armed with this optimized HILIC-reversed phase liquid chromatography platform, we identified 2554 nonredundant proteins from duplicate analyses of a Saccharomyces cerevisiae lysate, with the detected protein abundances spanning from approximately 41 to 10(6) copies per cell, which contained up to approximately 2092 different validated protein species with a dynamic range of concentrations of up to approximately 10(4) . This present study establishes a fully automated platform as a promising methodology to enable online coupling of different hydrophilic HILIC and reversed phase chromatography systems, thereby expanding the repertoire of multidimensional liquid chromatography for shotgun proteomics.

  11. Ultrafast Chiral Chromatography as the Second Dimension in Two-Dimensional Liquid Chromatography Experiments.

    PubMed

    Barhate, Chandan L; Regalado, Erik L; Contrella, Nathan D; Lee, Joon; Jo, Junyong; Makarov, Alexey A; Armstrong, Daniel W; Welch, Christopher J

    2017-03-21

    Chromatographic separation and analysis of complex mixtures of closely related species is one of the most challenging tasks in modern pharmaceutical analysis. In recent years, two-dimensional liquid chromatography (2D-LC) has become a valuable tool for improving peak capacity and selectivity. However, the relatively slow speed of chiral separations has limited the use of chiral stationary phases (CSPs) as the second dimension in 2D-LC, especially in the comprehensive mode. Realizing that the recent revolution in the field of ultrafast enantioselective chromatography could now provide significantly faster separations, we herein report an investigation into the use of ultrafast chiral chromatography as a second dimension for 2D chromatographic separations. In this study, excellent selectivity, peak shape, and repeatability were achieved by combining achiral and chiral narrow-bore columns (2.1 mm × 100 mm and 2.1 mm × 150 mm, sub-2 and 3 μm) in the first dimension with 4.6 mm × 30 mm and 4.6 mm × 50 mm columns packed with highly efficient chiral selectors (sub-2 μm fully porous and 2.7 μm fused-core particles) in the second dimension, together with the use of 0.1% phosphoric acid/acetonitrile eluents in both dimensions. Multiple achiral × chiral and chiral × chiral 2D-LC examples (single and multiple heart-cutting, high-resolution sampling, and comprehensive) using ultrafast chiral chromatography in the second dimension are successfully applied to the separation and analysis of complex mixtures of closely related pharmaceuticals and synthetic intermediates, including chiral and achiral drugs and metabolites, constitutional isomers, stereoisomers, and organohalogenated species.

  12. Methods to approximate reliabilities in single-step genomic evaluation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reliability of predictions from single-step genomic BLUP (ssGBLUP) can be calculated by inversion, but that is not feasible for large data sets. Two methods of approximating reliability were developed based on decomposition of a function of reliability into contributions from records, pedigrees, and...

  13. Percutaneous Cystgastrostomy as a Single-Step Procedure

    SciTech Connect

    Curry, L. Sookur, P.; Low, D.; Bhattacharya, S.; Fotheringham, T.

    2009-03-15

    The purpose of this study was to evaluate the success of percutaneous transgastric cystgastrostomy as a single-step procedure. We performed a retrospective analysis of single-step percutaneous transgastric cystgastrostomy carried out in 12 patients (8 male, 4 female; mean age 44 years; range 21-70 years), between 2002 and 2007, with large symptomatic pancreatic pseudocysts for whom up to 1-year follow-up data (mean 10 months) were available. All pseudocysts were drained by single-step percutaneous cystgastrostomy with the placement of either one or two stents. The procedure was completed successfully in all 12 patients. The pseudocysts showed complete resolution on further imaging in 7 of 12 patients with either enteric passage of the stent or stent removal by endoscopy. In 2 of 12 patients, the pseudocysts showed complete resolution on imaging, with the stents still noted in situ. In 2 of 12 patients, the pseudocysts became infected after 1 month and required surgical intervention. In 1 of 12 patients, the pseudocyst showed partial resolution on imaging, but subsequently reaccumulated and later required external drainage. In our experience, percutaneous cystgastrostomy as a single-step procedure has a high success rate and good short-term outcomes over 1-year follow-up and should be considered in the treatment of large symptomatic cysts.

  14. 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...

  15. Applications of nanomaterials in liquid chromatography: opportunities for separation with high efficiency and selectivity.

    PubMed

    Zhang, Zhengxiang; Wang, Zhiyong; Liao, Yiping; Liu, Huwei

    2006-08-01

    During recent decades, great efforts have been made to improve the chemical stability, selectivity, and separation efficiency of stationary phases in liquid chromatography. Significant progress has been achieved, especially after the introduction of nanomaterials into separation science. This review covers the applications of nanomaterials playing various roles in liquid chromatography. Future possibilities for developing nanomaterial-based stationary phases are also discussed.

  16. 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…

  17. 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.

  18. 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

  19. Temperature selectivity in reversed-phase high performance liquid chromatography.

    PubMed

    Dolan, John W

    2002-08-02

    Column temperature plays two important roles in reversed-phase high-performance liquid chromatography (RP-HPLC): control of retention (k) and control of selectivity (a). While changes in retention as a function of temperature are ubiquitous, selectivity changes for any given solute pair are more pronounced for ionized samples and samples with more polar substituents. With many samples, column temperature can be selected in a manner that optimizes resolution. The selectivity effects observed for temperature changes in RP-HPLC generally are complementary to those observed for mobile phase strength changes, so it is often possible to improve resolution by simultaneous optimization of temperature and mobile phase percent organic or gradient steepness. Computer simulation is a powerful tool for such optimization experiments. This paper reviews the influence of temperature on chromatographic selectivity for RP-HPLC.

  20. 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.

  1. Protein identification using nano liquid chromatography-tandem mass spectrometry.

    PubMed

    Negroni, Luc

    2007-01-01

    Tandem mass spectrometry is an efficient technique for the identification of peptides on the basis of their fragmentation pattern (MS/MS scan). It can generate individual spectra for each peptide, thereby creating a powerful tool for protein identification on the basis of peptide characterization. This important advance in automatic data acquisition has allowed an efficient association between liquid chromatography and tandem mass spectrometry, and the use of nanocolumns and nanoelectrospray ionization has dramatically increased the efficiency of this method. Now large sets of peptides can be identified at a femtomole level. At the end of the process, batch processing of the MS/MS spectra produces peptide lists that identify purified proteins or protein mixtures with high confidence.

  2. Solvent minimization in two-dimensional liquid chromatography.

    PubMed

    Horváth, Krisztián; Sepsey, Annamária; Hajós, Péter

    2015-01-23

    An algorithm was developed for the minimization of consumption of organic solvent in comprehensive two-dimensional liquid chromatography (2DLC). It was shown that one can reach higher peak capacities only by using more eluent. The equilibration volume of the second dimension, however, did not affect the solvent consumption significantly. Calculations confirmed that the same target peak capacity could be achieved by consuming significantly different volume of organic modifier depending on the number of fractions analyzed in the second dimension suggesting that 2D separations can be optimized for eluent consumption. It was shown that minimization of eluent usage requires the use of small and high efficient columns in the second dimension. A simple equation was derived for the calculation of the optimal number of collected fractions from the first dimension that allowed the minimization of eluent usage, cost and environmental impact of comprehensive 2DLC separations.

  3. Application of Inverse Liquid Chromatography for Surface Characterization of Biomaterials.

    PubMed

    Adamska, Katarzyna; Kadlec, Karol; Voelkel, Adam

    In the present study, a novel approach for surface characterization of ceramic biomaterials is proposed. Two ceramic biomaterials-hydroxyapatite and β-tricalcium phosphate-were examined by means of inverse liquid chromatography. The Abraham LFER model was applied for physicochemical characteristics of the surface. Different compounds, characterized by different polarity and different donor-acceptor properties of functional group, were used as test solutes. The chromatographic experiments were carried out with two compositions of the mobile phase: pure acetonitrile (MeCN) and the mixture of acetonitrile and water in 80:20 ratio (MeCN/H2O). Thus, the influence of mobile phase on sorption properties of hydroxyapatite and tricalcium phosphate surface was also discussed.

  4. 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.

  5. 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.

  6. Profiling of drug binding proteins by monolithic affinity chromatography in combination with liquid chromatography-tandem mass spectrometry.

    PubMed

    Zhang, Xuepei; Wang, Tongdan; Zhang, Hanzhi; Han, Bing; Wang, Lishun; Kang, Jingwu

    2014-09-12

    A new approach for proteome-wide profiling drug binding proteins by using monolithic capillary affinity chromatography in combination with HPLC-MS/MS is reported. Two immunosuppresive drugs, namely FK506 and cyclosporin A, were utilized as the experimental models for proof-of-concept. The monolithic capillary affinity columns were prepared through a single-step copolymerization of the drug derivatives with glycidyl methacrylate and ethylene dimethacrylate. The capillary chromatography with the affinity monolithic column facilitates the purification of the drug binding proteins from the cell lysate. By combining the capillary affinity column purification and the shot-gun proteomic analysis, totally 33 FK506- and 32 CsA-binding proteins including all the literature reported target proteins of these two drugs were identified. Among them, two proteins, namely voltage-dependent anion-selective channel protein 1 and serine/threonine-protein phosphatase PGAM5 were verified by using the recombinant proteins. The result supports that the monolithic capillary affinity chromatography is likely to become a valuable tool for profiling of binding proteins of small molecular drugs as well as bioactive compounds.

  7. Reliability of the retention factor estimations in liquid chromatography.

    PubMed

    Escuder-Gilabert, L; Bermúdez-Saldaña, J M; Villanueva-Camañas, R M; Medina-Hernández, M J; Sagrado, S

    2004-04-16

    The retention factor is one of the most universally used parameters in chromatography. However, large differences in the experimental retention factor values are observed when the same compound is injected in a given stationary/mobile phase system under intermediate precision conditions. Conventional protocols for estimating retention factors have problems that mainly arise from difficulties in the hold-up time measurements and the omission of the existence of extra-column times by practicing chromatographers. In the present paper, three different approaches for estimating retention factors are tested: (i) classical retention factor estimations based on the gross hold-up time, (ii) based on the real hold-up time (taking into account the extra-column time), and (iii) a new approach that uses 'relative' retention factors based on the use of an external standard. Assays are performed in micellar liquid chromatography (MLC) under intermediate precision conditions (different days, equipments, columns lengths, and mobile phase flow rates). The reliability of the three approaches tested is evaluated by means of precision studies, analysis of factors affecting retention factors, and uncertainty calculations. The approach based on 'relative' retention factors was found to be the most precise, reliable, and robust strategy for estimating retention factors.

  8. Cortisol production rates measured by liquid chromatography/mass spectrometry

    SciTech Connect

    Esteban, N.V.; Yergey, A.L. )

    1990-04-01

    Cortisol production rates (FPRs) in physiologic and pathologic states in humans have been investigated over the past 30 years. However, there has been conflicting evidence concerning the validity of the currently accepted value of FPRs in humans (12 to 15 mg/m2/d) as determined by radiotracer methodology. The present study reviews previous methods proposed for the measurement of FPRs in humans and discusses the applications of the first method for the direct determination of 24-hour plasma FPRs during continuous administration of a stable isotope, using a thermospray high-pressure liquid chromatography-mass spectrometry technique. The technique is fast, sensitive, and, unlike gas chromatography-mass spectrometry methods, does not require derivatization, allowing on-line detection and quantification of plasma cortisol after a simple extraction procedure. The results of determination of plasma FPRs by stable tracer/mass spectrometry are directly in units of mass/time and, unlike radiotracer methods, are independent of any determination of volume of distribution or cortisol concentration. Our methodology offers distinct advantages over radiotracer techniques in simplicity and reliability since only single measurements of isotope ratios are required. The technique was validated in adrenalectomized patients. Circadian variations in daily FRPs were observed in normal volunteers, and, to date, results suggest a lower FRP in normal children and adults than previously believed. 88 references.

  9. 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.

  10. Modern Aspects Of Fluorometric Detection In Liquid-Phase Chromatography

    NASA Astrophysics Data System (ADS)

    Bousquet, Bernard; Garnier, Jean P.; Dreux, Claude

    1983-10-01

    Recent advances are described in the combined use of fluorometric derivatization and high performance liquid chromatography (HPLC) for clinical chemistry determinations. Derivatives (especially dansyl derivatives) can be formed prior to chromatography in the case of estrogens, amino acids, and catecholamines. In post-column reactions, we preferred to use air-segmented reactions as they conform better to all the optimized chromatographic and spectrofluorometric parameters. Fluorescent derivatives produced from cate-cholamines, tryptophan and its metabolites, hydroxyindoles, tryptamine, amino acids, sugars, polyamines, and other substances are often sufficiently sensitive to be detected in picogram quantities by HPLC. Their reaction principle and some of their applications to samples are described. Recently, chemical excitation of fluorophore-like dansyl amino acid was proposed as a detection system for HPLC. By a post-column reaction, a fluorophore can be made to emit light by its reaction with trichlorophenyl oxalate (TCPO) and hydrogen peroxide. The detection limit of this system is about 10 fmol for each dansyl amino acid. Application of this new reaction to catecholamines opens up new prospects for fluorometric detection.

  11. Towards Chip Scale Liquid Chromatography and High Throughput Immunosensing

    SciTech Connect

    Ni, Jing

    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

  12. 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.

  13. Pressurized liquid extraction followed by liquid chromatography with tandem mass spectrometry to determine pharmaceuticals in mussels.

    PubMed

    Núñez, Mireia; Borrull, Francesc; Pocurull, Eva; Fontanals, Núria

    2016-02-01

    An analytical method based on pressurized liquid extraction and solid-phase extraction with a mixed-mode Oasis(®) MAX sorbent as cleanup, followed by liquid chromatography with electrospray ionization and tandem mass spectrometry was developed and validated for the determination of seven widely used pharmaceuticals in mussel species. The optimization of the pressurized liquid extraction and the solid-phase extraction parameters is described. The method provided extraction recoveries ranging from 61 to 90%, and limits of detection ranging from 2 to 50 ng/g (dry weight). The repeatability and reproducibility of the method, expressed as relative standard deviation, were lower than 15 and 19%, respectively. The method was successfully applied to the analysis of mussel samples from different locations. The analyses showed that salicylic acid was present in mussels at concentrations up to 177 ng/g (dry weight).

  14. Fast determination of sulfonamides from egg samples using magnetic multiwalled carbon nanotubes as adsorbents followed by liquid chromatography-tandem mass spectrometry.

    PubMed

    Xu, Yang; Ding, Jie; Chen, Haiyan; Zhao, Qi; Hou, Juan; Yan, Jin; Wang, Hui; Ding, Lan; Ren, Nanqi

    2013-09-01

    A simple and effective method based on magnetic separation has been developed for the extraction of sulfonamides (SAs) from egg samples using magnetic multiwalled carbon nanotubes (MMWCNTs) as an adsorbent. The MMWCNTs were simply prepared by depositing Fe3O4 onto MWCNTs that had been previously oxidised. The extraction procedure was carried out in a single step by blending and subsequently stirring the mixture of MMWCNTs and aqueous egg samples. The SAs were first extracted as described above, adsorbed onto the MMWCNTs directly and finally analysed by liquid chromatography-tandem mass spectrometry. The limits of detection obtained are in the range of 1.4-2.8 ng g(-1). The proposed method was successfully applied in determining SAs in the eggs obtained from laying hens fed with SA standards, and compared to eggs purchased from local markets. The results demonstrate that SAs were detectable in the incurred egg samples.

  15. 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.

  16. 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.

  17. Single-step route to diamond-nanotube composite

    PubMed Central

    2012-01-01

    Candle wax was used as a precursor for the production of a diamond-nanotube composite in a single step. The composite films were fabricated by sulfur-assisted hot-filament chemical vapor deposition technique. The morphology of the composite films was analyzed by scanning electron microscopy and transmission electron microscopy. Raman spectra of the films show characteristic diamond band at 1,332 cm−1, D-band around 1,342 cm−1, and graphitic G-band around 1,582 cm−1. The electron energy-loss spectroscopy recorded at the carbon K-edge region shows signature features of diamond and carbon nanotube in the fabricated material. The ability to synthesize diamond-nanotube composites at relatively low temperatures by a single-step process opens up new possibilities for the fabrication of nanoelectronic devices. PMID:23013660

  18. Single-step quantitative susceptibility mapping with variational penalties.

    PubMed

    Chatnuntawech, Itthi; McDaniel, Patrick; Cauley, Stephen F; Gagoski, Borjan A; Langkammer, Christian; Martin, Adrian; Grant, P Ellen; Wald, Lawrence L; Setsompop, Kawin; Adalsteinsson, Elfar; Bilgic, Berkin

    2017-04-01

    Quantitative susceptibility mapping (QSM) estimates the underlying tissue magnetic susceptibility from the gradient echo (GRE) phase signal through background phase removal and dipole inversion steps. Each of these steps typically requires the solution of an ill-posed inverse problem and thus necessitates additional regularization. Recently developed single-step QSM algorithms directly relate the unprocessed GRE phase to the unknown susceptibility distribution, thereby requiring the solution of a single inverse problem. In this work, we show that such a holistic approach provides susceptibility estimation with artifact mitigation and develop efficient algorithms that involve simple analytical solutions for all of the optimization steps. Our methods employ total variation (TV) and total generalized variation (TGV) to jointly perform the background removal and dipole inversion in a single step. Using multiple spherical mean value (SMV) kernels of varying radii permits high-fidelity background removal whilst retaining the phase information in the cortex. Using numerical simulations, we demonstrate that the proposed single-step methods reduce the reconstruction error by up to 66% relative to the multi-step methods that involve SMV background filtering with the same number of SMV kernels, followed by TV- or TGV-regularized dipole inversion. In vivo single-step experiments demonstrate a dramatic reduction in dipole streaking artifacts and improved homogeneity of image contrast. These acquisitions employ the rapid three-dimensional echo planar imaging (3D EPI) and Wave-CAIPI (controlled aliasing in parallel imaging) trajectories for signal-to-noise ratio-efficient whole-brain imaging. Herein, we also demonstrate the multi-echo capability of the Wave-CAIPI sequence for the first time, and introduce an automated, phase-sensitive coil sensitivity estimation scheme based on a 4-s calibration acquisition. Copyright © 2016 John Wiley & Sons, Ltd.

  19. A Method for the Quantitation of Trace Levels of Dimethyl Sulfoxide in Urine by High Performance Liquid Chromatography

    DTIC Science & Technology

    1989-05-01

    HIGH PERFORMANCE LIQUID CHROMATOGRAPHY by...for the sample cleanup and concentration, followed by separation by reversed phase high performance liquid chromatography . EXPERIMENTAL Materials...DIMETHYL SULFOXIDE IN URINE BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY 4. AUTHORS (Last name, first name, middle initial. If military, show rank, e.g.

  20. Determination of Dimethyl Sulfoxide (DMSO), Ethanol (ETOH), Formamide (F) and Glycerol/Formal (GF) by High Performance Liquid Chromatography (HPLC)

    DTIC Science & Technology

    1989-01-30

    HIGH PERFORMANCE LIQUID CHROMATOGRAPHY (HPLC...Classification) (U) Determination of Dimethyl Sulfoxide (DMSO), Ethanol, (ETOH), Formamide (F), and Glycerol/ Formal (GF) by High Performance Liquid Chromatography (HPLC...and 5). High performance liquid chromatography (HPLC) was the analytical method of choice for analyzing DMSO, ethanol, formamide and

  1. Determination of 5-Bromo-2’-Deoxyuridine (BrdU) in Well Water by High Performance Liquid Chromatography (HPLC)

    DTIC Science & Technology

    1992-09-01

    HIGH PERFORMANCE LIQUID CHROMATOGRAPHY (HPLC...Securrty Classification) Determination of 5-Bromo-2’-Deoxyuridine (BrdU) in Well Water by High Performance Liquid Chromatography (hPLC) 12. PERSONAL...PLOT OF BrdU STABILITY VERSUS TIME ....................... 10 ii DETERMINATION OF 5-BROMO-2’-DEOXY-URIDINE (BrdU) IN WELL WATER BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

  2. Three dimensional liquid chromatography coupling ion exchange chromatography/hydrophobic interaction chromatography/reverse phase chromatography for effective protein separation in top-down proteomics.

    PubMed

    Valeja, Santosh G; Xiu, Lichen; Gregorich, Zachery R; Guner, Huseyin; Jin, Song; Ge, Ying

    2015-01-01

    To address the complexity of the proteome in mass spectrometry (MS)-based top-down proteomics, multidimensional liquid chromatography (MDLC) strategies that can effectively separate proteins with high resolution and automation are highly desirable. Although various MDLC methods that can effectively separate peptides from protein digests exist, very few MDLC strategies, primarily consisting of 2DLC, are available for intact protein separation, which is insufficient to address the complexity of the proteome. We recently demonstrated that hydrophobic interaction chromatography (HIC) utilizing a MS-compatible salt can provide high resolution separation of intact proteins for top-down proteomics. Herein, we have developed a novel 3DLC strategy by coupling HIC with ion exchange chromatography (IEC) and reverse phase chromatography (RPC) for intact protein separation. We demonstrated that a 3D (IEC-HIC-RPC) approach greatly outperformed the conventional 2D IEC-RPC approach. For the same IEC fraction (out of 35 fractions) from a crude HEK 293 cell lysate, a total of 640 proteins were identified in the 3D approach (corresponding to 201 nonredundant proteins) as compared to 47 in the 2D approach, whereas simply prolonging the gradients in RPC in the 2D approach only led to minimal improvement in protein separation and identifications. Therefore, this novel 3DLC method has great potential for effective separation of intact proteins to achieve deep proteome coverage in top-down proteomics.

  3. 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

  4. Simultaneous determination of PPCPs, EDCs, and artificial sweeteners in environmental water samples using a single-step SPE coupled with HPLC-MS/MS and isotope dilution.

    PubMed

    Tran, Ngoc Han; Hu, Jiangyong; Ong, Say Leong

    2013-09-15

    A high-throughput method for the simultaneous determination of 24 pharmaceuticals and personal care products (PPCPs), endocrine disrupting chemicals (EDCs) and artificial sweeteners (ASs) was developed. The method was based on a single-step solid phase extraction (SPE) coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and isotope dilution. In this study, a single-step SPE procedure was optimized for simultaneous extraction of all target analytes. Good recoveries (≥ 70%) were observed for all target analytes when extraction was performed using Chromabond(®) HR-X (500 mg, 6 mL) cartridges under acidic condition (pH 2). HPLC-MS/MS parameters were optimized for the simultaneous analysis of 24 PPCPs, EDCs and ASs in a single injection. Quantification was performed by using 13 isotopically labeled internal standards (ILIS), which allows correcting efficiently the loss of the analytes during SPE procedure, matrix effects during HPLC-MS/MS and fluctuation in MS/MS signal intensity due to instrument. Method quantification limit (MQL) for most of the target analytes was below 10 ng/L in all water samples. The method was successfully applied for the simultaneous determination of PPCPs, EDCs and ASs in raw wastewater, surface water and groundwater samples collected in a local catchment area in Singapore. In conclusion, the developed method provided a valuable tool for investigating the occurrence, behavior, transport, and the fate of PPCPs, EDCs and ASs in the aquatic environment.

  5. Determination of L-ephedrine, pseudoephedrine, and caffeine in rat plasma by liquid chromatography-tandem mass spectrometry.

    PubMed

    Cooper, Stephen D; Fletcher, Brenda L; Silinski, Melanie A Rehder; Brown, Sherri S; Lodge, Jon W; Fernando, Reshan A; Collins, Bradley J

    2011-07-01

    A rapid and simple liquid chromatography tandem mass spectrometry method was developed and validated for the simultaneous determination of L-ephedrine, pseudoephedrine, and caffeine in male Fisher-344 rat plasma at nanogram-per-milliliter concentrations for use in support of toxicology studies. Only 25 μL of plasma is required, and extraction is performed using a simple, single-step protein precipitation. The method was validated over a range of 2.09 to 5460 ng/mL for L-ephedrine, 2.09 to 5050 ng/mL for pseudoephedrine and 2.03 to 5340 ng/mL for caffeine. A binary gradient elution at 0.3 mL/min was used with a Waters XBridge Phenyl (2.1 × 150 mm, 3.5 μm) column and a Waters XBridge Phenyl 2.1- × 10-mm guard column at ambient temperature. The mobile phase consisted of 10 mM ammonium acetate in water (pH 5.0) and methanol. Caffeine trimethyl-(13)C(3) was used as the internal standard. The method was evaluated for linearity, recovery, precision, accuracy, and stability, and it was successfully applied in toxicokinetic studies of ephedrine, administered alone, in combination with caffeine, and in the herbal source Ma Huang.

  6. Microfluidic liquid chromatography system for proteomic applications and biomarker screening.

    PubMed

    Lazar, Iulia M; Trisiripisal, Phichet; Sarvaiya, Hetal A

    2006-08-01

    A microfluidic liquid chromatography (LC) system for proteomic investigations that integrates all the necessary components for stand-alone operation, i.e., pump, valve, separation column, and electrospray interface, is described in this paper. The overall size of the LC device is small enough to enable the integration of two fully functional separation systems on a 3 in. x 1 in. glass microchip. A multichannel architecture that uses electroosmotic pumping principles provides the necessary functionality for eluent propulsion and sample valving. The flow rates generated within these chips are fully consistent with the requirements of nano-LC platforms that are routinely used in proteomic applications. The microfluidic device was evaluated for the analysis of a protein digest obtained from the MCF7 breast cancer cell line. The cytosolic protein extract was processed according to a shotgun protocol, and after tryptic digestion and prefractionation using strong cation exchange chromatography (SCX), selected sample subfractions were analyzed with conventional and microfluidic LC platforms. Using similar experimental conditions, the performance of the microchip LC was comparable to that obtained with benchtop instrumentation, providing an overlap of 75% in proteins that were identified by more than two unique peptides. The microfluidic LC analysis of a protein-rich SCX fraction enabled the confident identification of 77 proteins by using conventional data filtering parameters, of 39 proteins with p < 0.001, and of 5 proteins that are known to be cancer-specific biomarkers, demonstrating thus the potential applicability of these chips for future high-throughput biomarker screening applications.

  7. Determination of the lipophilic antipsychotic drug ziprasidone in rat plasma and brain tissue using liquid chromatography-tandem mass spectrometry.

    PubMed

    Zhang, Guodong; Terry, Alvin V; Bartlett, Michael G

    2008-07-01

    A simple, sensitive and robust liquid chromatography/electrospray ionization tandem mass spectrometry (LCESI-MS/MS) method with low matrix effects was developed and validated for the quantification of the lipophilic antipsychotic ziprasidone from rat plasma and brain tissue. Ziprasidone was extracted from rat plasma and brain homogenate using a single-step liquid-liquid extraction. Ziprasidone was separated on an Agilent Eclipse XDB C8 column (150 x 2.1 mm i.d., 5 microm) column using a mobile phase of acetonitrile-0.02% ammonia in water (pH 7.20 adjusted with formic acid) using gradient elution. Ziprasidone was detected in the positive ion mode using multiple reaction monitoring. The method was validated and the specificity, linearity, lower limit of quantitation (LLOQ), precision, accuracy, recovery, matrix effects and stability were determined. The LLOQ was 0.2 ng/mL for plasma and 0.833 ng/g for brain tissue. The method was linear over the concentration range from 0.2 to 200.0 ng/mL for plasma and 0.833-833.3 ng/g for brain tissue. The correlation coefficient (R2) values were more than 0.996 for both plasma and brain homogenate. The precision and accuracy intra-day and inter-day were better than 8.13%. The relative and absolute recovery was above 81.0% and matrix effects were lower than 5.2%. This validated method has been successfully used to quantify the rat plasma and brain tissue concentration of ziprasidone after chronic treatment.

  8. Extensive database of liquid phase diffusion coefficients of some frequently used test molecules in reversed-phase liquid chromatography and hydrophilic interaction liquid chromatography.

    PubMed

    Song, Huiying; Vanderheyden, Yoachim; Adams, Erwin; Desmet, Gert; Cabooter, Deirdre

    2016-07-15

    Diffusion plays an important role in all aspects of band broadening in chromatography. An accurate knowledge of molecular diffusion coefficients in different mobile phases is therefore crucial in fundamental column performance studies. Correlations available in literature, such as the Wilke-Chang equation, can provide good approximations of molecular diffusion under reversed-phase conditions. However, these correlations have been demonstrated to be less accurate for mobile phases containing a large percentage of acetonitrile, as is the case in hydrophilic interaction liquid chromatography. A database of experimentally measured molecular diffusion coefficients of some 45 polar and apolar compounds that are frequently used as test molecules under hydrophilic interaction liquid chromatography and reversed-phase conditions is therefore presented. Special attention is given to diffusion coefficients of polar compounds obtained in large percentages of acetonitrile (>90%). The effect of the buffer concentration (5-10mM ammonium acetate) on the obtained diffusion coefficients is investigated and is demonstrated to mainly influence the molecular diffusion of charged molecules. Diffusion coefficients are measured using the Taylor-Aris method and hence deduced from the peak broadening of a solute when flowing through a long open tube. The validity of the set-up employed for the measurement of the diffusion coefficients is demonstrated by ruling out the occurrence of longitudinal diffusion, secondary flow interactions and extra-column effects, while it is also shown that radial equilibration in the 15m long capillary is effective.

  9. 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.

  10. 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.

  11. Determination of sulfite in foods by headspace liquid chromatography

    SciTech Connect

    Lawrence, J.F.; Chadha, R.K.

    1988-01-01

    Sulfite was determined in a variety of foods by liquid chromatography (LC) after the samples were mixed with a solution containing mannitol, FeSO/sub 4/, and Na/sub 2/HPO/sub 4/, adjusted to pH 11, and left to stand for 15 min at room temperature. An aliquot of the mixture was placed in a headspace vial and mixed with 50% H/sub 3/PO/sub 4/. After 15 min, a portion of the headspace was removed with a syringe containing LC mobile phase without acetonitrile. The syringe was shaken and an aliquot of the solution was analyzed on an anion exchange column with a mobile phase of 0.03M methane sulfonate (pH 10.8) containing 5% acetonitrile. Sulfite was detected amperometrically (glassy carbon electrode) at +0.7 V. The method was successfully compared to the FDA-modified Monier-Williams procedure for a variety of foods. Minimum detectable levels were about 1 ..mu..g/g, based on a 15 g sample.

  12. Gas-liquid chromatography of fecal neutral steriods.

    PubMed

    Gerhardt, K O; Gehrke, C W; Rogers, I T; Flynn, M A; Hentges, D J

    1977-05-21

    A method is described for the analysis of fecal neutral steriods with a dual-column gas-liquid chromatography (GLC) system. After saponification of the fecal slurry, the neutral steroids were extracted with hexane. The GLC separation of the compounds and quantitation were achieved by simultaneous injection of the derivatized and derivatized aliquots of the extract onto dual colmuns under identical conditions. The neutral steroids of interest were than identified by matching the retention times with those of known standards, and identification was confirmed by use of an interfaced GLC high-resolution mass spectrometry system. The detection limit was 0.003 mg of steroid/g of fecal slurry. The pricision of the method is illustrated by a relative standard diviation of 2-10% and a recovery of neutral steroids from 73-96%. The method was applied to the determination of fecal neutral steroids in a "High protein diet in colon cancer study". A considerably larger level of coprostanone than of coprostanol was observed. Data on neutral steroids in fecal samples from subjects on different diets are the subject of a separate publication.

  13. Are analysts doing method validation in liquid chromatography?

    PubMed

    Ruiz-Angel, M J; García-Alvarez-Coque, M C; Berthod, A; Carda-Broch, S

    2014-08-01

    Method validation is being applied in the reported analytical methods for decades. Even before this protocol was defined, authors already somehow validated their methods without full awareness. They wished to assure the quality of their work. Validation is an applied approach to verify that a method is suitable and rugged enough to function as a quality control tool in different locations and times. The performance parameters and statistical protocols followed throughout a validation study vary with the source of guidelines. Before single laboratory validation, an analytical method should be fully developed and optimized. The purpose of the validation is to confirm performance parameters that are determined during method development, and it should provide information on how the method will perform under routine use. An unstable method may require re-validation. Further method development and optimization will be needed if validation results do not meet the accepted performance standards. When possible, the validation protocol should also be conducted as a collaborative study by multiple laboratories, on different instruments, reagents, and standards. At this point, it would be interesting to know how people are validating their methods. Are they evaluating all defined validation parameters? Are they indicating the followed guidelines? Is re-validation really currently used? Is validation performed by a single laboratory, or is it a collaborative work by several laboratories? Is it an evolving discipline? In this survey, we will try to answer these questions focused to the field of liquid chromatography.

  14. Separation of microcystins and nodularins by ultra performance liquid chromatography.

    PubMed

    Spoof, Lisa; Neffling, Milla-Riina; Meriluoto, Jussi

    2009-11-15

    Four ultra performance liquid chromatography (UPLC) columns with different reversed-phase characteristics were tested in the chromatographic separation of 10 microcystins and three nodularins, cyanobacterial peptide toxins. The columns had been designed by the manufacturer to withstand the ultra-high pressure generated by sub-2microm stationary phase particles and the Waters ACQUITY UPLC system in ultra-fast separations. The gradient mobile phase consisted of water and acetonitrile, both acidified with trifluoroacetic acid, with three gradient rise times: 1, 1.5 and 2min. The UV detection of the toxins was performed by a photodiode array detector. The chromatographic performance was evaluated both visually and by calculating chromatographic parameters such as capacity factor, resolution, peak width at half height, selectivity and peak asymmetry. The best chromatographic performance as judged by visual inspection was given by the ACQUITY BEH Shield RP18 and ACQUITY BEH Phenyl columns. The BEH Shield RP18 column showed excellent selectivity and resolution of chosen peak pairs considered as critical. A further advantage of the UPLC system was the high sample throughput with a total analysis time of 3.12min (injection-to-injection) equalling to 461 separations per 24h.

  15. Analysis of Cordyceps by multi-column liquid chromatography.

    PubMed

    Qian, Zhengming; Li, Shaoping

    2017-03-01

    Cordyceps is a famous traditional Chinese medicine (TCM) that has been used in China for hundreds of years. In the present study a multi-column liquid chromatography (MC-LC) system was developed for the qualitative analysis of macromolecules and micromolecules in Cordyceps. The MC-LC system includes a size exclusion pre-column, a size exclusion column (SEC) and a reversed phase column (RP) which were controlled by column-switching valves. The sample was separated by the size exclusion pre-column into two fractions (macromolecules and micromolecules). These fractions were further separated on SEC and RP columns, respectively. A diode array detector (DAD) and a mass spectrometer (MS) were used to detect the components. This MC-LC method was utilized for analysis of Cordyceps samples. Two macromolecular peaks and 15 micromolecular peaks were found in Cordyceps, and 11 of the micromolecular peaks were identified as adenosine-5'-monophosphate (AMP), phenylalanine, uridine, hypoxanthine, inosine, guanine, guanosine, deoxyadenosine-5'-monophosphate (dAMP), adenosine, adenine and cordycepin (or its isomer). This method is useful for quality control of Cordyceps.

  16. Strategies for metabolite profiling based on liquid chromatography.

    PubMed

    Saurina, Javier; Sentellas, Sonia

    2017-02-15

    This paper aims at covering the principal strategies based on liquid chromatography (LC) for metabolite profiling in the field of drug discovery and development. The identification of metabolites generated in the organism is an important task during the early stages of preclinical research to define the most proper strategy for optimizing, adjusting metabolic clearance and minimizing bioactivation. An early assessment of the metabolite profile may be critical since metabolites can contribute to pharmacological and/or toxicological effects. The study of metabolites first involves their synthesis/generation and their further characterization and structural elucidation. For such a purpose, both in vitro and in vivo methods are commonly used for the generation of the corresponding metabolites. Next, analytical methods are used to tackle identification and characterization studies. Among the arsenal of techniques available in our labs, we will focus on LC, especially coupled to mass spectrometry (LC-MS), as one of the most powerful approaches for metabolite identification, characterization and quantification. Here, the topic of metabolite profiling based on LC will be addressed and representative examples of different possibilities will be discussed.

  17. New method for determining total dietary fiber by liquid chromatography.

    PubMed

    Ohkuma, K; Matsuda, I; Katta, Y; Tsuji, K; Ohkuma, K; Matsuda, I; Katta, Y; Tsuji, K

    2000-01-01

    The molecular weight limit of water-soluble dietary fiber (SDF) determined by the Prosky method was studied by liquid chromatography (LC). It was confirmed that only SDF with an average degree of polymerization of 12 or higher can be determined by the Prosky method. Total dietary fiber (TDF) was determined by 2 additional methods using LC. In the first method, the total quantity of insoluble dietary fiber (IDF) and high molecular weight SDF (HMSDF) was determined according to the modified Prosky method (MES-TRIS buffer-based). The quantitatively collected final filtrate was analyzed by LC for the quantity of low molecular weight SDF (LMSDF), and the 2 quantities were totaled to obtain TDF. TDF values thus determined for rice, polished or unpolished, soybean flour, and pressed barley were higher than those determined by the Prosky method by approximately 6, 3.5, and 3.5%, respectively. In the second method, direct determination by LC analysis was done on samples after enzymatic treatment according to the Prosky method. Results showed that the determination of LMSDF, in particular, was highly accurate and more effective. In both of these methods, the quantity of LMSDF was determined from its chromatographic peak area ratio to glucose as an internal standard, which was produced by hydrolysis.

  18. A Fiber Optic Colorimeter For Liquid Phase Chromatography Of Aminoacids

    NASA Astrophysics Data System (ADS)

    Donati, S.; Tambosso, T.

    1989-01-01

    Liquid phase chromatography is a well known technique routinely used in analytical chemistry for assays and measurements of aminoacids 1,2. Basically, the solution is pumped at high pressure in a long capillary tube (the chromatographic column) to fraction out the constituents, is mixed to a suitable reactant (usually ninhydrine) so as to develop a spectral absorbance, and is finally analyzed in a flow cell by a colorimeter. With ninhydrine, the reaction product is DIDA (diketo-hydrindilidene-diketolhydrin diamine) which exhibits absorbance peaks at 440 nm (blue) and 570 nm (yellow) in a proportion dependent on the specific aminoacid (Fig. 1), while the amplitude of peaks is proportional to the aminoacid concentration in view of Lambert-Beer law. Besides the two measurement channels of absorbance, either of which or the sum of which is taken as the output signal, a third channel at the wavelength 690 nm at which DIDA is transparent (Ar = 0), is used internally as the reference to the first two. Thus, the colorimeter is actually a spectrophotometer with two fixed-wavelength channels, each referenced in wavelength. In this paper, we report on the design and engineering of a colorimeter aimed to medium/high performances, high reliability and low cost. Use of fiber optics as the beamsplitter of the optical channels is shown to give substantial advantages.

  19. Hydrophilic interaction liquid chromatography with alcohol as a weak eluent.

    PubMed

    Liu, Min; Ostovic, Judy; Chen, Emily X; Cauchon, Nina

    2009-03-20

    There has been a significant increase of interest in polar compound separation by hydrophilic interaction liquid chromatography (HILIC), in which acetonitrile is mostly used as a weak eluent. Although replacing acetonitrile with alcohols as organic modifiers has been previously reported, the separation mechanism was poorly understood. In this paper we explored the separation mechanism through the method development for the analysis of the trace amounts of polar and basic hydrazines, which were genotoxic in nature. Separation parameters such as the type and concentration of alcohol, acid modifier, and buffer in mobile phase as well as the choice of stationary phase and column temperature were studied. The data indicated that both electrostatic and hydrophilic interactions contributed to the retention and separation of the hydrazines. The results presented here provide insight into the adjustment of the retention and separation of analytes in HILIC mode with alcohol as a weak eluent. The optimized HILIC method coupled with chemiluminescent nitrogen detection (CLND) is simple and sensitive (reporting limit at 0.02%) and was applied to simultaneous analysis of hydrazine and 1,1-dimethylhydrazine in a pharmaceutical intermediate.

  20. 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

    2014-10-03

    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.

  1. Single-step assembly of complex 3-D microstructures

    SciTech Connect

    Hui, E.E.; Howe, R.T.; Rodgers, M.S.

    2000-01-04

    This paper describes three-dimensional microstructures fabricated in a planar process and assembled in a single step. Multiple plates are constrained by hinges in such a way as to reduce the assembly process to a single degree-of-freedom of motion. Serial microassembly of these structures is simpler; moreover, self-assembly using hydrodynamic forces during release is much more feasible than with earlier, multiple degree-of-freedom hinged structures. A 250-{micro}m corner cube reflector, a 6-sided closed box, and a 3-D model of the Berkeley Campanile clock tower have been demonstrated in the 4-level polysilicon SUMMiT MEMS foundry.

  2. How to separate ionic liquids: use of hydrophilic interaction liquid chromatography and mixed mode phases.

    PubMed

    Lamouroux, C; Foglia, G; Le Rouzo, G

    2011-05-20

    This chromatographic study deals with the development of a convenient and versatile method to separate Room Temperature Ionic Liquids. Different modes of chromatography were studied. The study attempts to answer the following question: "what were the most important interactions for the separation of ionic liquids?". The results show that the essential interactions to assure a good retention of RTILs are the ionic ones and that hydrophobic interactions play a role in the selectivity of the separation. The separation of five imidazolium salt with a traditional diol columns in Hydrophilic Interaction Chromatography (HILIC) was demonstrated. It shows that neutral diol grafted column allows an important retention that we assume is due to the capability of diol to develop a thick layer of water. Furthermore, stationary phase based on mixed interaction associating ion exchange and hydrophobic properties were studied. Firstly, it will be argued that it is possible to separate RTILs with a convenient retention and resolution according to a reverse phase elution with the Primesep columns made of a brush type long alkyl chain with an embedded negatively charged functional group. Secondly, a sucessful separation of RTILs in HILIC mode with a mixed phase column containing a cationic exchanger and a hydrophobic octyl chain length will be demonstrated.

  3. 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.

  4. 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...

  5. 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)

  6. IDENTIFICATION OF POLAR DRINKING WATER DISINFECTION BY-PRODUCTS USING LIQUID CHROMATOGRAPHY - MASS SPECTROMETRY

    EPA Science Inventory

    A qualitative method using 2,4-dinitrophenylhydrazine (DNPH) derivatization followed by analysis with liquid chromatography (LC)/negative ion-electrospray mass spectrometry (MS) was developed for identifying polar aldehydes and ketones in ozonated drinking water. This method offe...

  7. Qualitative Analysis of Analgesic Tablets: An Experiment Employing High Pressure Liquid Chromatography.

    ERIC Educational Resources Information Center

    Beaver, Rodney W.; And Others

    1983-01-01

    Describes an experiment on the qualitative analysis of several over-the-counter analgesic tablets. Background information, procedures used (including high pressure liquid chromatography), and typical student results are included. (JN)

  8. [Applications of fast and ultra performance liquid chromatography in the analysis of Chinese herbal medicines].

    PubMed

    Liu, Ying; Zhou, Jianliang; Li, Ping

    2009-09-01

    The analysis of chemical components of Chinese herbal medicines (CHMs) is one of the most critical issues not only for screening and analyzing the bioactive components but also for controlling their quality. However, due to the complexity of the chemical constituents of CHMs, it is difficult to separate them on column within a short time. In the recent, the fast and ultra performance liquid chromatography, including ultra high pressure liquid chromatography, high performance liquid chromatography based on the monolithic columns and high temperature liquid chromatography, are of particular interest because of the high resolution and fast analytical speed provided by these techniques. This overview covers the principle and separation characteristics of these techniques, as well as their applications in Chinese herbal medicines.

  9. Matrix Solid-Phase Dispersion Coupled with High-Performance Liquid Chromatography Diode Array Detection for Simultaneous Determination of Four Lipophilic Constituents from Salvia miltiorrhiza Bunge.

    PubMed

    Wang, Zhibing; Ma, Siyu; Zhang, Qian; He, Shuang; Li, Qing; Hu, Jianxue; Zhang, Hanqi

    2016-11-29

    A simple, rapid and efficient method based on matrix solid-phase dispersion coupled with high-performance liquid chromatography was developed for determination of lipophilic constituents, including dihydrotanshinone, tanshinone I, cryptotanshinone and tanshinone II A in Salvia miltiorrhiza Bunge Box-Behnken design was employed for optimization of the extraction conditions of matrix solid-phase dispersion, including mass ratio of dispersant to sample, volume of elution solvent, and amount of cleanup reagent. The optimal experimental results were obtained using 0.27 g of acid alumina as dispersant, 13 mL of acetonitrile as elution solvent and 0.36 g of acid alumina as cleanup reagent. The target analytes was determined by high-performance liquid chromatography. The recoveries of tanshinones obtained by analyzing the spiked samples were from 83.81% to 93.74% and relative standard deviations from 2.87% to 6.83%. Matrix solid-phase dispersion integrated the extraction and cleanup into a single step, which provides the advantages of being simple, fast and convenient. Compared with other conventional methods, the present method consumed less time and less organic solvent. The results demonstrate that this method has potential for the determination of active constituents and the quality control of traditional Chinese medicine.

  10. 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.

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

    SciTech Connect

    Dumont, Philip John

    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.

  12. Effect of arm swing on single-step balance recovery.

    PubMed

    Cheng, Kuangyou B; Huang, Yi-Chang; Kuo, Shih-Yu

    2014-12-01

    Balance recovery techniques are useful not only in preventing falls but also in many sports activities. The step strategy plays an important role especially under intense perturbations. However, relatively little is known about the effect of arm swing on stepping balance recovery although considerable arm motions have been observed. The purpose of this study was to examine how the arms influence kinematic and kinetic characteristics in single-step balance recovery. Twelve young male adults were released from three forward-lean angles and asked to regain balance by taking a single step under arm swing (AS) and arm constrained (AC) conditions. It was found that unconstrained arms had initial forward motion and later upward motion causing increased moment of inertia of the body, which decreased falling angular velocity and allowed more time for stepping. The lengthened total balance time included weight transfer and stepping time, although duration increase in the latter was significant only at the largest lean angle. In contrast, step length, step velocity, and vertical ground reaction forces on the stepping foot were unaffected by arm swing. Future studies are required to investigate optimal movement strategies for the arms to coordinate with other body segments in balance recovery and injury reduction.

  13. Single-Step Process toward Achieving Superhydrophobic Reduced Graphene Oxide.

    PubMed

    Li, Zhong; Tang, Xiu-Zhi; Zhu, Wenyu; Thompson, Brianna C; Huang, Mingyue; Yang, Jinglei; Hu, Xiao; Khor, Khiam Aik

    2016-05-04

    We report the first use of spark plasma sintering (SPS) as a single-step process to achieve superhydrophobic reduced graphene oxide (rGO). It was found that SPS was capable of converting smooth and electrically insulating graphene oxide (GO) sheets into highly electrically conductive rGO with minimum residual oxygen and hierarchical roughness which could be well retained after prolonged ultrasonication. At a temperature of 500 °C, which is lower than the conventional critical temperature for GO exfoliation, GO was successfully exfoliated, reduced, and hierarchically roughened. rGO fabricated by only 1 min of treatment at 1050 °C was superhydrophobic with a surface roughness (Ra) 10 times as large as that of GO as well as an extraordinarily high C:O ratio of 83.03 (atom %) and water contact angle of 153°. This demonstrates that SPS is a superior GO reduction technique, which enabled superhydrophobic rGO to be quickly and effectively achieved in one single step. Moreover, the superhydrophobic rGO fabricated by SPS showed an impressive bacterial antifouling and inactivation effect against Escherichia coli in both aqueous solution and the solid state. It is envisioned that the superhydrophobic rGO obtained in this study can be potentially used for a wide range of industrial and biomedical applications, such as the fabrication of self-cleaning and antibacterial surfaces.

  14. 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%.

  15. Liquid chromatography method to determine polyamines in thermosetting polymers.

    PubMed

    Dopico-García, M S; López-Vilariño, J M; Fernández-Martínez, G; González-Rodríguez, M V

    2010-05-14

    A simple, robust and sensitive analytical method to determine three polyamines commonly used as hardeners in epoxy resin systems and in the manufacture of polyurethane is reported. The studied polyamines are: one tetramine, TETA (triethylenetetramine), and two diamines, IPDA (Isophorone diamine) and TCD-diamine (4,7-methano-1H-indene-5,?-dimethanamine, octahydro-). The latter has an incompletely defined structure, and, as far as we know, has not been previously determined by other methods. All three polyamines contain primary amines; TETA also contains secondary amines. The analytical method involves derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate, used for the first time for these compounds, followed by high performance liquid chromatography (HPLC) analysis with a fluorescence (FL) detector (lambda excitation 248nm, lambda emision 395nm). The HPLC-DAD-LTQ Orbitrap MS was used in order to provide structural information about the obtained derivatized compounds. The hybrid linear ion trap LTQ Orbitrap mass spectrometer has been introduced in recent years and provides a high mass accuracy. The structures of the derivatized analytes were identified from the protonated molecular ions [M+H](+) and corresponded to the fully labelled analytes. The following analytical parameters were determined for the method using the HPLC-FL: linearity, precision (2.5-10%), instrumental precision intraday (0.8-1.5%) and interday (2.9-6.3%), and detection limits (0.02-0.14mgL(-1)). The stability of stock solutions and derivatized compounds was also investigated. The method was applied to determine the amine free content in epoxy resin dust collected in workplaces.

  16. Separation of stereoisomers of several furan derivatives by capillary gas chromatography-mass spectrometry, supercritical fluid chromatography, and liquid chromatography using chiral stationary phases.

    PubMed

    Kasai, Hiroko F; Tsubuki, Masayoshi; Takahashi, Kazunori; Shirao, Mika; Matsumoto, Yohichiro; Honda, Toshio; Seyama, Yoshiyuki

    2002-11-15

    The direct separation of several stereoisomers (enantiomers and geometrical isomers) of furan derivatives, important intermediates for the synthesis of physiologically active natural products, was achieved using capillary gas chromatography/mass spectrometry with a per-O-methyl-beta-cyclodextrin, supercritical fluid chromatography and high-performance liquid chromatography with a tris(3,5-dimethylphenylcarbamate) of cellulose or amylose for the chiral stational phases, respectively. The temperature dependence of the peak resolution (Rs) and the retention factor (k) over the range of 110-130 degrees was studied using crotyl furfuryl ether in gas chromatography. Successive increases in the Rs value and of the difference between the k value of the E-isomer and the k value of the Z-isomer were observed when the gradient temperature was decreased. The per-O-methyl-beta-cyclodextrin column was suitable for use with volatile furan ethers whose molecular masses are between 150 and 180. In conclusion, the separation of thermally unstable furan derivatives was accomplished using supercritical fluid chromatography and high-performance liquid chromatography.

  17. 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.

  18. 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)

  19. Liquid chromatography/tandem mass spectrometry method for the simultaneous determination of olanzapine, risperidone, 9-hydroxyrisperidone, clozapine, haloperidol and ziprasidone in rat plasma.

    PubMed

    Zhang, Guodong; Terry, Alvin V; Bartlett, Michael G

    2007-01-01

    A simple, sensitive and rapid liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method was developed and validated for simultaneous quantification of olanzapine, clozapine, ziprasidone, haloperidol, risperidone, and its active metabolite 9-hydroxyrisperidone, in rat plasma using midazolam as internal standard (IS). The analytes were extracted from rat plasma using a single step liquid-liquid extraction technique. The compounds were separated on a Waters Atlantis dC-18 (30 mm x 2.1 mm i.d., 3 microm) column using a mobile phase of acetonitrile/5 mM ammonium formate (pH 6.1 adjusted with formic acid) with gradient elution. All of the analytes were detected in positive ion mode using multiple reaction monitoring (MRM). The method was validated and the specificity, linearity, lower limit of quantitation (LLOQ), precision, accuracy, recoveries and stability were determined. LLOQ was 0.1 ng/mL and correlation coefficient (R(2)) values for the linear range of 0.1-100 ng/mL were 0.997 or greater for all the analytes. The intra-day and inter-day precision and accuracy were better than 8.05%. The relative and absolute recovery was above 77% and matrix effects were low for all the analytes except for ziprasidone. This validated method has been successfully used to quantify the plasma concentration of the analytes after chronic treatment with antipsychotic drugs.

  20. Simultaneous quantification of three pyranocoumarins of Peucedanum praeruptorum in rat plasma by liquid chromatography-tandem mass spectrometry: application to pharmacokinetic study.

    PubMed

    Zhou, Guangyu; Chen, Guozhen; Liu, Hongbo

    2015-04-01

    A simple, rapid and robust liquid chromatography-tandem mass spectrometry was established and validated for simultaneous quantifications of three pyranocoumarins (praeruptorin A-C) in rat plasma. Following a single-step liquid-liquid extraction, the analytes were separated on a reversed-phase C18 column with a mobile phase consisting of methanol and 10 mM ammonium acetate solution (70 : 30, v/v) at a constant flow rate of 0.3 mL/min. The linear calibration curves were obtained over the concentration ranges 2.93-1470 ng/mL for praeruptorin A, 1.47-734 ng/mL for praeruptorin B and 2.00-1000 ng/mL for praeruptorin C. The within-batch accuracy was -8.6 to 7.5% for praeruptorin A, -9.5 to 12.0% for praeruptorin B and -10.5 to 12.5% for praeruptorin C, respectively. The between-batch accuracy was -3.5 to 1.4% for praeruptorin A, -8.7 to 3.4% for praeruptorin B and -6.0 to 4.3% for praeruptorin C, respectively. The within-batch and between-batch precisions were ≤13.1 and ≤8.2%, respectively. This method is suitable to simultaneously determine the three pyranocoumarins in plasma and thus to investigate the pharmacokinetics of the pyranocoumarins of Peucedanum praeruptorum in rats.

  1. 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.

  2. High-pressure liquid chromatography of aromatic amines

    NASA Technical Reports Server (NTRS)

    Young, P. R.

    1979-01-01

    Analysis made on commercially available liquid chromatograph demonstrates high-pressure liquid chromatographic conditions for separation of approximately 50 aromatic amines ranging from simple aniline derivatives to complex multiring di- and tri-amines.

  3. 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

    2016-03-04

    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.

  4. Orthogonal separation on one beta-cyclodextrin column by switching reversed-phase liquid chromatography and hydrophilic interaction chromatography.

    PubMed

    Feng, Jia-tao; Guo, Zhi-mou; Shi, Hui; Gu, Jiang-ping; Jin, Yu; Liang, Xin-miao

    2010-06-15

    A dual retention combined with reversed-phase liquid chromatography (RP-LC) and hydrophilic interaction chromatography (HILIC) has been observed on beta-cyclodextrin (beta-CD) bonded stationary phase. A typical U-shaped retention curve was achieved owing to dual retention mechanism. Based on this observation, a beta-CD column can be operated under reversed-phase liquid chromatography (RP-LC) and hydrophilic interaction chromatography (HILIC) modes. Two-dimensional liquid chromatography (2D-LC) analysis can be realized on just a beta-CD column by switching these two different separation modes. In this study, off-line 2D-LC analysis for a natural product was carried out to prove the orthogonal separation between RP-LC and HILIC modes on a Click beta-CD column. Herba Hedyotis Diffusae, the whole grass of Hedyotis Diffusae wild was extracted with water, pretreated with macroporous resin and then first separated at RP-LC mode on the Click beta-CD column to obtain successive fractions, which were then reanalyzed at HILIC mode on the same Click beta-CD column. The result proved that both separation modes on the Click beta-CD column have good retention and peak shape, and these two separation modes have good orthogonality. 2D-LC analysis revealed abundant information in the natural product. Especially numerous minor components were enriched and separated. The mobile phase used in RP-LC and HILIC modes can be same and the switch between these two separation modes is easily realized by changing the ratio of the acetonitrile and water. Hence the mobile phase in this 2D-LC system is completely compatible. This advantage makes this combination is an appropriate 2D-LC method for the solutes having retention at both separation modes.

  5. 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.

  6. Partition coefficients of organic compounds in new imidazolium based ionic liquids using inverse gas chromatography.

    PubMed

    Revelli, Anne-Laure; Mutelet, Fabrice; Jaubert, Jean-Noël

    2009-06-05

    Partition coefficients of organic compounds in four ionic liquids: 1-ethanol-3-methylimidazolium tetrafluoroborate, 1-ethanol-3-methylimidazolium hexafluorophosphate, 1,3-dimethylimidazolium dimethylphosphate and 1-ethyl-3-methylimidazolium diethylphosphate were measured using inverse gas chromatography from 303.3 to 332.55K. The influence of gas-liquid and gas-solid interfacial adsorption of different solutes on ionic liquids was also studied. Most of the polar solutes were retained largely by partition while light hydrocarbons were retained predominantly by interfacial adsorption on the ionic liquids studied in this work. The solvation characteristics of the ionic liquids were evaluated using the Abraham solvation parameter model.

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

    NASA Astrophysics Data System (ADS)

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

    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 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 trace levels of the military explosives, RDX, TNT, and PETN from denim, colored flannel, vinyl, and canvas extracted in methanol and filtered using no additional sample cleanup of the sample extract prior to analysis. The filtered methanol extracts were injected directly into several different column types and analyzed by high performance liquid chromatography using ultraviolet detection and/or gas chromatography using electron capture detection. This paper describes general screening methods that were used to determine the presence of explosives (RDX, TNT, and PETN) in unknown samples of denim, colored flannel, vinyl and canvas in addition to techniques that have been optimized for quantification of each explosive from the substrate extracts.

  8. Separation of Nitration By-Products in Commercial-Grade Trinitro-Toluene by High Performance Liquid Chromatography.

    DTIC Science & Technology

    1982-06-01

    MRL-TN-464 SEPARATION OF NITRATION BY-PRODUCTS IN COMMERCIAL-GRADE TITR-TOLUENE BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY Peter J. Sanders ABSTRACT...UNCLASSIFIED TITLE SEPARATION OF NITRATION BY-PRODUCTS IN COMMERCIAL-GRADE TRXNITRO-TOLUENE BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY AUTHOR(S...PRODUCTS IN COMMERCIAL-GRADE TRINITRO-TOLUENE BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY 16 INTRODUCTION Fbr some time, a need has existed for the

  9. Single-step PCR in molecular diagnosis of hepatitis C virus infection.

    PubMed Central

    Farma, E; Boeri, E; Bettini, P; Repetto, C M; McDermott, J; Lillo, F B; Varnier, O E

    1996-01-01

    The diagnostic utility of two PCR systems and three PCR detection methods for hepatitis C virus (HCV) RNA was evaluated in serum samples. A nested PCR was considered the reference assay and was compared with two single-step PCR methods: the first is based on the detection of PCR products by liquid hybridization with a 32P-end-labeled probe, and the second is the Roche Amplicor colorimetric assay using microwell plate hybridization with a specific nucleic acid probe. Using the Pelicheck HCV RNA Eurohep genotype 1 proficiency panel, our laboratory achieved medium-high levels of performance with all three methods. The highest sensitivity was, however, observed with the isotopic single-step PCR (ss-PCR) method. The analytical sensitivity of ss-PCR with isotopic detection and ss-PCR with colorimetric detection was identical to that of nested PCR, with a 100% result concordance. Comparison of ss-PCR with enzyme-linked immunosorbent and RIBA assays in the analysis of clinical samples showed a high concordance. ss-PCR methods appear more suitable for diagnostic application. Nevertheless, HCV RNA PCR cannot be considered a screening assay; it should be requested in the presence of reactive serology or specific clinical symptomatology with altered liver parameters, and it is a potential tool for the follow-up of patients with HCV infection. PMID:8940466

  10. Quality evaluation of moluodan concentrated pill using high-performance liquid chromatography fingerprinting coupled with chemometrics.

    PubMed

    Tao, Lingyan; Zhang, Qing; Wu, Yongjiang; Liu, Xuesong

    2016-12-01

    In this study, a fast and effective high-performance liquid chromatography method was developed to obtain a fingerprint chromatogram and quantitative analysis simultaneously of four indexes including gallic acid, chlorogenic acid, albiflorin and paeoniflorin of the traditional Chinese medicine Moluodan Concentrated Pill. The method was performed by using a Waters X-bridge C18 reversed phase column on an Agilent 1200S high-performance liquid chromatography system coupled with diode array detection. The mobile phase of the high-performance liquid chromatography method was composed of 20 mmol/L phosphate solution and acetonitrile with a 1 mL/min eluent velocity, under a detection temperature of 30°C and a UV detection wavelength of 254 nm. After the methodology validation, 16 batches of Moluodan Concentrated Pill were analyzed by this high-performance liquid chromatography method and both qualitative and quantitative evaluation results were achieved by similarity analysis, principal component analysis and hierarchical cluster analysis. The results of these three chemometrics were in good agreement and all indicated that batch 10 and batch 16 showed significant differences with the other 14 batches. This suggested that the developed high-performance liquid chromatography method could be applied in the quality evaluation of Moluodan Concentrated Pill.

  11. Systematic comparison of sensitivity between hydrophilic interaction liquid chromatography and reversed phase liquid chromatography coupled with mass spectrometry.

    PubMed

    Periat, Aurélie; Boccard, Julien; Veuthey, Jean-Luc; Rudaz, Serge; Guillarme, Davy

    2013-10-18

    Hydrophilic interaction liquid chromatography (HILIC) appears as a promising strategy to increase sensitivity with electrospray ionization source (ESI/MS). In the present study, peak heights, background noises and signal-to-noise ratios (S/N) obtained with HILIC-MS/MS and RPLC-MS/MS conditions were systematically compared using a dataset of 56 basic drugs possessing diverse physico-chemical properties. Various mobile phase conditions were investigated, including different pH (3 and 6 in HILIC; 3, 6 and 9 in RPLC) and flow rates (300, 600 and 1000μL/min). The average gain in sensitivity obtained between HILIC and RPLC was equal to 7 and 10 at pH 3 and 6, respectively. However, this value was not reliable, since it was altered by a few compounds possessing an "extreme" behaviour (gain in sensitivity from 100-fold to >8000-fold better). Then, the median gain in sensitivity, equal to 4 in our case, whatever the pH, should be considered. For about 90% of the tested compounds and analytical conditions, the best S/N was systematically attained under HILIC mode. Thanks to PCA representation, it was shown that the basic compounds with pKa between 6 and 8 generally had the best sensitivity in HILIC at pH 6, while the best sensitivity for basic analytes possessing pKa higher than 8 was usually obtained in HILIC at pH 3. As previously reported, the sensitivity gain in HILIC vs. RPLC was explained by the difference in acetonitrile concentration at elution (in average 29% ACN in RPLC and 82% ACN in HILIC at pH 6) leading to better analytes' desolvation. However, it seems that this high proportion of solvent also favourably influenced the ionization by modifying pH and pKa. Indeed the weakest bases of our training set of compounds (pKa between 2 and 5) showed an unexpectedly strong gain in sensitivity, between 20 and 100-fold in comparison to RPLC. These results prove that the ionic character of analytes in solution (i.e., pKa and pH) and the ionization mechanism (i.e., proton

  12. 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.

  13. Therapeutic drug monitoring of clozapine and norclozapine in human serum using ultra-performance liquid chromatography- tandem mass spectrometry.

    PubMed

    Ming, Dong Sheng; Heathcote, John

    2009-05-01

    A rapid, sensitive, and specific method was developed and validated using ultra-performance liquid chromatography- tandem mass spectrometry (UPLC-MS-MS) for simultaneous determination of clozapine and its major metabolite norclozapine in human serum. The compounds were extracted from serum by a single step protein precipitation and analyzed using a UPLC-triple-quadrupole detection (TQD) system. Separation of compounds was achieved on a BEH C18 (50 mm x 2.1 mm, 1.7 microm) analytical column using methanol and water (both containing 0.2% ammonium hydroxide) as the mobile phase at a flow rate of 0.40 mL/min. The compounds were ionized in the electrospray ionization ion source of the TQD and were detected in the multiple reaction monitoring (MRM) mode. The MRM transitions m/z 327 --> 270 and m/z 313 --> 192 for clozapine and norclozapine, respectively, were used for the quantification ions. Clozapine transition 327 --> 192 and norclozapine transition 313 --> 270 were used as confirmation ions. Linear calibration curves in human serum were generated over the range of 10-2000 ng/mL for both clozapine and norclozapine with a correlation coefficient (r(2)) > 0.9970. Calibration curves exhibited consistent linearity and reproducibility. Interassay coefficients of variation (CV) (n = 20) were 3.04-4.94% for clozapine and 2.84-6.07% for norclozapine. Intra-assay CVs (n = 6, 20 days) were 0.61-1.26% and 1.62-2.21% for clozapine and norclozapine, respectively. The extraction recoveries were larger than 95% for both clozapine and norclozapine. The method was applied to the quantification of clozapine and norclozapine in the sera of schizophrenic patients, and the data revealed that the concentrations of two compounds varied significantly in the patients treated with clozapine.

  14. Single step channeling in glass interior by femtosecond laser

    SciTech Connect

    Kongsuwan, Panjawat; Wang Hongliang; Lawrence Yao, Y.

    2012-07-15

    Channeling inside a transparent material, glass, by femtosecond laser was performed by using a single step process rather than hybrid processes that combine the laser irradiation with an additional tool or step to remove the material. Tightly focusing of a single femtosecond laser pulse using proper optical and laser processing parameters could induce the micro-explosion and could create voids inside transparent materials, and the effects of these parameters on the resultant feature geometry and channel length were studied. Understanding of the channel length variation at different locations from the specimen surface could enhance prediction capability. Taking into account of the laser, material, and lens properties, numerical models were developed to predict the absorption volume shape and size at different focusing depths below the surface of a specimen. These models will also be validated with the variation in feature and channel lengths inside the specimen obtained from the experiments. Spacing between adjacent laser pulses and laser parameters was varied to investigate effects of channel overlapping and its influence on long channel formation.

  15. A single-step method of liposome preparation.

    PubMed

    Zawada, Zygmunt

    2004-01-01

    All the liposome preparation protocols, which involve drug encapsulation are multi-step processes, i.e. they consist of one or several steps of preparation and homogenization. The conditions of converting all lipids into vesicles smaller than 200 nm were determined by replacing ultrasonication with mechanical stirring of the buffer and solution of lipids in a low-boiling point organic solvent or solvents in a simple preparator. Preferably, the process should be carried out at a temperature higher than the temperature of the gel/fluid phase transition (T(m)), and higher than the boiling point of the organic solvent(s) used to obtain the lipid solution. For many lipid membrane compositions, the products of preparation are as follows: a dominant fraction of unilamellar vesicles (vesicle of diameter smaller than 200 nm) and a fraction of much larger multivesicular or multilamellar vesicles, easily separated by simple centrifugation at 15000xg. If PEG-phosphatidylethanolamine or cholesteryl palmitate are additional membrane components, multivescular or multilamellar vescicles are virtually absent in the final product, of a single-step process and all the used lipids were quantitatively converted into vesicles smaller than 200 nm in diameter.

  16. Single Step Sintered Calcium Phosphate Fibers from Avian EGG Shell

    NASA Astrophysics Data System (ADS)

    Dadhich, Prabhash; Das, Bodhisatwa; Dhara, Santanu

    2013-11-01

    Different forms of calcium-phosphate (Hydoxyapatite, α-TCP, β-TCP, CDHA) minerals are found to be major component of bone tissue. Development of calcium-phosphate (CaP) based fibrous microstructures is of significant research interest worldwide owing to its improved mechanical properties and higher interconnectivity. Here we represent a method for single step sintered wet-spun Fibers of calcium phosphate from avian egg shells for biomedical applications. Raw egg shell powder was mixed with chitosan solution and Phosphoric acid. The mixture is milled in a ball mill overnight and then filtered. The slurry was de-aired using 100 microliter 1-octanol per 100 ml of slurry as antifoaming and wet spun in coagulation bath. Fiber was dried overnight and sintered at different temperatures for microstructure and phase analysis. Both green and sintered Fibers were physico-chemical characterized by SEM, EDX, XRD, TGA, DSC, FTIR, and stereo-zoom microscopy. The fibers obtained in this procedure are found to have highly porous interconnected structures which can provide good cell adhesion and therefore can be used for bioactive scaffold making.

  17. Virtual substitution scan via single-step free energy perturbation.

    PubMed

    Chiang, Ying-Chih; Wang, Yi

    2016-02-05

    With the rapid expansion of our computing power, molecular dynamics (MD) simulations ranging from hundreds of nanoseconds to microseconds or even milliseconds have become increasingly common. The majority of these long trajectories are obtained from plain (vanilla) MD simulations, where no enhanced sampling or free energy calculation method is employed. To promote the 'recycling' of these trajectories, we developed the Virtual Substitution Scan (VSS) toolkit as a plugin of the open-source visualization and analysis software VMD. Based on the single-step free energy perturbation (sFEP) method, VSS enables the user to post-process a vanilla MD trajectory for a fast free energy scan of substituting aryl hydrogens by small functional groups. Dihedrals of the functional groups are sampled explicitly in VSS, which improves the performance of the calculation and is found particularly important for certain groups. As a proof-of-concept demonstration, we employ VSS to compute the solvation free energy change upon substituting the hydrogen of a benzene molecule by 12 small functional groups frequently considered in lead optimization. Additionally, VSS is used to compute the relative binding free energy of four selected ligands of the T4 lysozyme. Overall, the computational cost of VSS is only a fraction of the corresponding multi-step FEP (mFEP) calculation, while its results agree reasonably well with those of mFEP, indicating that VSS offers a promising tool for rapid free energy scan of small functional group substitutions. This article is protected by copyright. All rights reserved.

  18. Single-step intercalating dye strategies for DNA damage studies.

    PubMed

    Paidipalli, Manasa; Pjescic, Ilija; Hindmarsh, Patrick L; Crews, Niel D

    2013-08-01

    Many analytical protocols exist for the quantification of varied types of DNA damage, which span a range of complexity and sensitivity. As an alternative or companion to existing procedures, this article demonstrates the application of quantitative PCR (qPCR) and high-resolution DNA melting analysis (HRMA) to the detection and quantification of intramolecular DNA damage and/or strand breaks. These proven molecular biology methods are essentially single-step processes. When implemented with a third-generation saturating DNA dye, high sensitivity can be obtained. The experiments presented here demonstrate how DNA damage can inhibit amplification of the affected molecules. This corresponding decrease in the initial concentration of amplifiable DNA can be measured with qPCR. In addition, damage in the form of intramolecular dimerization and strand breaks alters the stored energy in the hydrogen bonds between the two strands in the dsDNA molecule. This significantly affects the thermal stability, which can be measured with extreme precision using HRMA. Simplified damage models were used in these experiments: UV-C irradiation to produce photoproducts, and restriction enzyme digestion to simulate double-strand breaks. The findings of this work, however, can be intuitively applied to the broad scope of DNA damage mechanisms.

  19. 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.

  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. 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.

  2. Plasma lipid analysis by hydrophilic interaction liquid chromatography coupled with electrospray ionization tandem mass spectrometry.

    PubMed

    Sonomura, Kazuhiro; Kudoh, Shinobu; Sato, Taka-Aki; Matsuda, Fumihiko

    2015-06-01

    A novel method for the analysis of endogenous lipids and related compounds was developed employing hydrophilic interaction liquid chromatography with electrospray ionization tandem mass spectrometry. A hydrophilic interaction liquid chromatography with carbamoyl stationary phase achieved clear separation of phosphatidylcholine, lysophosphatidylcholine, sphingomyelin, ceramide, and mono-hexsosyl ceramide groups with good peak area repeatability (RSD% < 10) and linearity (R(2) > 0.99). The established method was applied to human plasma assays and a total of 117 endogenous lipids were successfully detected and reproducibly identified. In addition, we investigated the simultaneous detection of small polar metabolites such as amino and organic acids co-existing in the same biological samples processed in a single analytical run with lipids. Our results show that hydrophilic interaction liquid chromatography is a useful tool for human plasma lipidome analysis and offers more comprehensive metabolome coverage.

  3. Determination of muscimol and ibotenic acid in Amanita mushrooms by high-performance liquid chromatography and liquid chromatography-tandem mass spectrometry.

    PubMed

    Tsujikawa, Kenji; Kuwayama, Kenji; Miyaguchi, Hajime; Kanamori, Tatsuyuki; Iwata, Yuko; Inoue, Hiroyuki; Yoshida, Takemi; Kishi, Tohru

    2007-06-01

    A reliable analytical method was developed for the quantification and identification of muscimol (MUS) and ibotenic acid (IBO), the toxic constituents of Amanita muscaria and Amanita pantherina. MUS and IBO were extracted from mushrooms by aqueous methanol and derivatized with dansyl chloride (DNS-Cl). After extraction with ethyl acetate and evaporation of the solvent, the residue was ethylated with 1.25 M hydrogen chloride in ethanol. The resulting derivatives were quantified by high-performance liquid chromatography with UV detection and identified by liquid chromatography electrospray ionization tandem mass spectrometry. Calibration curves were linear in the range of 25-2500 ppm for MUS and 40-2500 ppm for IBO, respectively. This method was successfully applied to identify and quantify MUS and IBO in Amanita mushrooms naturally grown and circulated in the drug market.

  4. 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.

  5. Fluorimetric assay for ornithine decarboxylase by high-performance liquid chromatography.

    PubMed

    Haraguchi, K; Kai, M; Kohashi, K; Ohkura, Y

    1980-12-05

    A highly sensitive method for the assay of ornithine decarboxylase in sample solutions prepared from rat tissue homogenate is described which employs high-performance liquid chromatography with fluorescence detection. Putrescine formed from ornithine under the optimal conditions for the enzyme reaction is treated by Cellex P column chromatography for clean-up and converted into the fluorescamine derivative in the presence of cupric ion which inhibits the reaction of interfering amines with fluorescamine. The derivative is separated by reversed-phase chromatography on LiChrosorb RP-18 with linear gradient elution. The lower limit of detection for putrescine formed enzymatically is 5 pmol.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Comprehensive two-dimensional normal-phase liquid chromatography × reversed-phase liquid chromatography for analysis of toad skin.

    PubMed

    Li, Jia-Fu; Yan, Xia; Wu, Yun-Long; Fang, Mei-Juan; Wu, Zhen; Qiu, Ying-Kun

    2017-04-15

    An analytical two-dimensional normal-phase liquid chromatography × reversed-phase liquid chromatography (2D NPLC × RPLC) system was constructed with a newly developed thermal evaporation assisted adsorption (TEAA) interface. This novel TEAA interface with heating temperature above solvent boiling point allowed fast removal of organic NPLC solvent and successfully solved the solvent incompatibility problem between NPLC and RPLC. The system achieved rapid on-line solvent exchange between the two dimensions within a short modulation time of 190 s and was applied in the analysis of an extract from the skin of Bufo bufo gargarizans. This is the first time to realize the on-line comprehensive analysis of a moderate polar natural product by coupling NPLC with reversed phase ultra-high performance liquid chromatography (UHPLC). To be highlighted, with the TEAA interface, the 2D NPLC × RPLC system provided excellent resolution and orthogonality (75.2%), when compared with that of 2D RPLC × RPLC.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Analysis of nitroguanidine in Aqueous Solutions by HPLC (High Performance Liquid Chromatography) with electrochemical Detection and Voltammetry

    DTIC Science & Technology

    1987-04-01

    The nitroguanidine was analyzed by high performance liquid chromatography (HPLC) with electrochemical detection at a hanging miercury drop electrode...previously reported on the application of solid sorbent collection techniques to the analysis of several explosives in water by high performance liquid chromatography (HPLC

  16. 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...

  17. Single-Step Ironmaking from Ore to Improve Energy Efficiency

    SciTech Connect

    S.K. Kawatra; B. Anamerie; T.C. Eisele

    2005-10-01

    The pig iron nugget process was developed as an alternative to the traditional blast furnace process by Kobe Steel. The process aimed to produce pig iron nuggets, which have similar chemical and physical properties to blast furnace pig iron, in a single step. The pig iron nugget process utilizes coal instead of coke and self reducing and fluxing dried green balls instead of pellets and sinters. In this process the environmental emissions caused by coke and sinter production, and energy lost between pellet induration (heat hardening) and transportation to the blast furnace can be eliminated. The objectives of this research were to (1) produce pig iron nuggets in the laboratory, (2) characterize the pig iron nugget produced and compare them with blast furnace pig iron, (3) investigate the furnace temperature and residence time effects on the pig iron nugget production, and (4) optimize the operational furnace temperatures and residence times. The experiments involved heat treatment of self reducing and fluxing dried green balls at various furnace temperatures and residence times. Three chemically and physically different products were produced after the compete reduction of iron oxides to iron depending on the operational furnace temperatures and/or residence times. These products were direct reduced iron (DRI), transition direct reduced iron (TDRI), and pig iron nuggets. The increase in the carbon content of the system as a function of furnace temperature and/or residence time dictated the formation of these products. The direct reduced iron, transition direct reduced iron, and pig iron nuggets produced were analyzed for their chemical composition, degree of metallization, apparent density, microstructure and microhardness. In addition, the change in the carbon content of the system with the changing furnace temperature and/or residence time was detected by optical microscopy and Microhardness measurements. The sufficient carbon dissolution required for the

  18. [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.

  19. 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

    2016-06-05

    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.

  20. 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...

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

    SciTech Connect

    Johnson, Steven

    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.

  2. 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.

  3. 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…

  4. 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...

  5. 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…

  6. 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)

  7. Models of retention of adamantylamidrazones in reversed-phase high-performance liquid chromatography

    NASA Astrophysics Data System (ADS)

    Prokopov, S. V.; Kurbatova, S. V.

    2011-05-01

    Rules governing the chromatographic behavior of some amidrazones of the adamantane series were studied under the conditions of reversed-phase high-performance liquid chromatography. The characteristics of the retention of sorbates in elution by aqueous-acetonitrile phases with various compositions were calculated. Correlations between the structure and physicochemical characteristics of sorbate molecules and their retention were studied.

  8. 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)

  9. 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...

  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. 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…

  12. Sorption of catechins under conditions of reverse-phase high-efficiency liquid chromatography

    NASA Astrophysics Data System (ADS)

    Shafigulin, R. V.; Egorova, K. V.; Bulanova, A. V.

    2010-08-01

    The physico-chemical principles of catechin sorption from various polar solvents onto silica gel modified with octadecyl groups were studied. Thermodynamic characteristics of the sorption were calculated, and the applicability of different models of retention was demonstrated for catechins under the conditions of reverse-phase high-efficiency liquid chromatography.

  13. 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...

  14. 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...

  15. 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.

  16. 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…

  17. 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…

  18. 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)

  19. A Laboratory Experiment in Pharmaceutical Analysis: Analysis of Diazepam Tablets by High Pressure Liquid Chromatography

    ERIC Educational Resources Information Center

    Bailey, Leonard

    1978-01-01

    The experiment described was developed for the third-year course in inorganic and analytical pharmaceutical chemistry to provide students with "hands-on" experience with high pressure liquid chromatography. Assay procedures are given along with experimental parameters and student results. (LBH)

  20. 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…

  1. 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.

  2. Recent Advance in Liquid Chromatography/Mass Spectrometry Techniques for Environmental Analysis in Japan

    PubMed Central

    Suzuki, Shigeru

    2014-01-01

    The techniques and measurement methods developed in the Environmental Survey and Monitoring of Chemicals by Japan’s Ministry of the Environment, as well as a large amount of knowledge archived in the survey, have led to the advancement of environmental analysis. Recently, technologies such as non-target liquid chromatography/high resolution mass spectrometry and liquid chromatography with micro bore column have further developed the field. Here, the general strategy of a method developed for the liquid chromatography/mass spectrometry (LC/MS) analysis of environmental chemicals with a brief description is presented. Also, a non-target analysis for the identification of environmental pollutants using a provisional fragment database and “MsMsFilter,” an elemental composition elucidation tool, is presented. This analytical method is shown to be highly effective in the identification of a model chemical, the pesticide Bendiocarb. Our improved micro-liquid chromatography injection system showed substantially enhanced sensitivity to perfluoroalkyl substances, with peak areas 32–71 times larger than those observed in conventional LC/MS. PMID:26819891

  3. 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.

  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 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

  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

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

    2016-01-08

    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.

  6. Nontargeted lipidomic characterization of porcine organs using hydrophilic interaction liquid chromatography and off-line two-dimensional liquid chromatography-electrospray ionization mass spectrometry.

    PubMed

    Cífková, Eva; Holčapek, Michal; Lísa, Miroslav

    2013-09-01

    Lipids form a significant part of animal organs and they are responsible for important biological functions, such as semi-permeability and fluidity of membranes, signaling activity, anti-inflammatory processes, etc. We have performed a comprehensive nontargeted lipidomic characterization of porcine brain, heart, kidney, liver, lung, spinal cord, spleen, and stomach using hydrophilic interaction liquid chromatography (HILIC) coupled to electrospray ionization mass spectrometry (ESI/MS) to describe the representation of individual lipid classes in these organs. Detailed information on identified lipid species inside classes are obtained based on relative abundances of deprotonated molecules [M-H](-) in the negative-ion ESI mass spectra, which provides important knowledge on phosphatidylethanolamines and their different forms of fatty acyl linkage (ethers and plasmalogens), phosphatidylinositols, and hexosylceramides containing nonhydroxy- and hydroxy-fatty acyls. The detailed analysis of identified lipid classes using reversed-phase liquid chromatography in the second dimension was performed for porcine brain to determine more than 160 individual lipid species containing attached fatty acyls of different acyl chain length, double-bond number, and positions on the glycerol skeleton. The fatty acid composition of porcine organs is determined by gas chromatography with flame ionization detection after the transesterification with sodium methoxide.

  7. 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.

  8. 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

  9. Vortex-assisted ionic liquid dispersive liquid-liquid microextraction for the determination of sulfonylurea herbicides in wine samples by capillary high-performance liquid chromatography.

    PubMed

    Gure, Abera; Lara, Francisco J; García-Campaña, Ana M; Megersa, Negussie; del Olmo-Iruela, Monsalud

    2015-03-01

    A new sample treatment, namely vortex-assisted ionic liquid dispersive liquid-liquid microextraction (VA-IL-DLLME), followed by capillary liquid chromatography has been developed for the determination of four sulfonylurea herbicides (SUHs): flazasulfuron (FS), prosulfuron (PS), primisulfuron-methyl (PSM) and triflusulfuron-methyl (TSM) in wine samples. The ionic liquid (IL) 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]) was used as extraction solvent and was dispersed using methanol into the sample solution, assisted by a vortex mixer. Various parameters influencing the extraction efficiency, such as type and amount of IL, type and volume of disperser solvent, sample pH, salting-out effect, vortex and centrifugation time were studied. Under the optimum conditions, the limits of detection and quantification of the proposed method were in the ranges of 3.2-6.6 and 10.8-22.0 μg kg(-1), respectively; lower than the maximum residue limits set by the EU for these matrices. The proposed method was successfully applied to different wine samples and satisfactory recoveries were obtained.

  10. Ionic-liquid-based dispersive liquid-liquid microextraction combined with high-performance liquid chromatography for the determination of multiclass pesticide residues in water samples.

    PubMed

    Tadesse, Bezuayehu; Teju, Endale; Gure, Abera; Megersa, Negussie

    2015-03-01

    Ionic-liquid-based dispersive liquid-liquid microextraction in combination with high-performance liquid chromatography and diode array detection has been proposed for the simultaneous analysis of four multiclass pesticide residues including carbaryl, methidathion, chlorothalonil, and ametryn from water samples. The major experimental parameters including the type and volume of ionic liquid, sample pH, type, and volume of disperser solvent and cooling time were investigated and optimum conditions were established. Under the optimum experimental conditions, limits of detection and quantification of the method were in the range of 0.1-1.8 and 0.4-5.9 μg/L, respectively, with satisfactory enrichment factors ranging from 10-20. The matrix-matched calibration curves, which were constructed for lake water, as a representative matrix were linear over wide range with coefficients of determination of 0.996 or better. Intra- and interday precisions, expressed as relative standard deviations, were in the range of 1.1-9.7 and 3.1-7.8%, respectively. The relative recoveries of the spiked environmental water samples at one concentration level were in the range of 77-102%. The results of the present study revealed that the proposed method is simple, fast, and uses environmentally friendly extraction solvent for the analysis of the target pesticide residues in environmental water samples.

  11. Determination of pyrazon residues in water by reversed phase high performance liquid chromatography.

    PubMed

    Ahmad, I

    1982-01-01

    A simple analytical method is described for the quantitative determination of pyrazon residues in water. It involves high performance liquid chromatography with ultraviolet detection at 270 nm. The procedure is used to determine 2 ppb to 1 ppm levels of pyrazon in water. The traditional liquid-liquid extraction method has been replaced by an adsorption-trapping method for the extraction of pyrazon. Average recovery of pyrazon from the laboratory spiked samples was 98.1%. The method can be used for water samples with concentrations as low as 2 ppb.

  12. 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.

  13. 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.

  14. 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.

  15. High-performance liquid chromatography of organophosphorus insecticides.

    PubMed

    Szalontai, G

    1976-09-01

    The high-performance liquid chromatographic behaviour of 23 organophosphorus insecticides has been studied on a stainless-steel column packed with silica gel. It has been stated that the usual classification of organophosphorus compounds into phosphonic, phosphoric, thiophosphoric and dithiophosphoric acid ester types gives some information about their adsorption properties. The chromatographic conditions of the analyses and a method for separation of the stereoisomers of tetrachlorvinphos are presented.

  16. Simultaneous determination of hypericin and hyperforin in human plasma and serum using liquid-liquid extraction, high-performance liquid chromatography and liquid chromatography-tandem mass spectrometry.

    PubMed

    Pirker, R; Huck, C W; Bonn, G K

    2002-09-25

    A method for the simultaneous extraction of hypericin and hyperforin from a St. John's Wort extract, which is used in case of moderate depressions and skin injuries, from human plasma and serum by liquid-liquid extraction (LLE) with n-hexane-ethylacetate (70:30, w/w) was developed. A reversed-phase high-performance liquid chromatographic (RP-HPLC) method with UV, fluorescence (FLD) and mass spectrometric (MS) detection using electrospray ionization (ESI) was used to identify and quantify hypericin and hyperforin in the extracts from blood samples. Linearity was obtained in the ranges 8.4-28.7 ng/ml (hypericin) and 21.6-242.6 ng/ml (hyperforin). Recoveries were between 32.2 and 35.6% for hypericin and 100.1 and 89.9% for hyperforin. Intra-day accuracy and precision for this method ranged between 3.2 and 4.3% and 2.6 and 2.8%, respectively. After validation of the LLE, the method was tested on real plasma samples which were obtained by ingestion of St. John's Wort extract capsules. Blood samples were taken 2, 4, and 6 h after ingestion. Finally, this method proved to be highly suitable for clinical and pharmacologically relevant studies.

  17. Two-dimensional countercurrent chromatography×high performance liquid chromatography with heart-cutting and stop-and-go techniques for preparative isolation of coumarin derivatives from Peucedanum praeruptorum Dunn.

    PubMed

    Liu, Jing-Lan; Wang, Xin-Yuan; Zhang, Ling-Ling; Fang, Mei-Juan; Wu, Yun-Long; Wu, Zhen; Qiu, Ying-Kun

    2014-12-29

    Pure compounds isolated from complex natural plants are important for drug discovery. This study describes a novel two-dimensional hyphenation of counter-current chromatography and high-performance liquid chromatography (2D CCC×HPLC) with heart-cutting and stop-and-go techniques for preparative isolation of multiple targets components from Peucedanum praeruptorum Dunn (Umbelliferae) crude extracts in a single step. The CCC and HPLC were hyphenated via a 4-port valve equipped at the post-end of the CCC column, to heart cut the impure fractions to the 2nd dimensional HPLC for further separation. Furthermore, the stop-and-go flow scheme was applied in the 1st dimensional CCC to fit with the time constraints of the 2nd dimensional preparative HPLC. Last but not least, an optimal biphasic solvent system composed of n-heptane/acetone/water (31:50:19, v/v/v) with suitable Kd values and a higher retention of the stationary phase was chosen to separate target compounds, resulting in the improvement of the CCC column efficiency. By taking the advantages of this rationally designed system, sixteen coumarins were isolated from 1.0g of P. praeruptorum crude extract, with HPLC purity from 90.1% to 99.5%, in a single 2D separation run. More interestingly, two minor linear coumarins and one angular coumarin were isolated from P. praeruptorum Dunn for the first time. As far as we known, this is the first report on the combination of heart-cutting technique and stop-and-go protocol in 2D CCC×HPLC system, by which good separations on comprehensive matrix were achieved. We expect that this approach may have broad applications for simultaneous isolation and purification of multiple components from other complex plant-derived natural products.

  18. Characterization of sodium carboxymethyl cellulose by comprehensive two-dimensional liquid chromatography.

    PubMed

    Shakun, Maria; Heinze, Thomas; Radke, Wolfgang

    2015-10-05

    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.

  19. 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.

  20. Comprehensive two-dimensional liquid chromatography for the separation of protonated and deuterated polystyrene.

    PubMed

    Sinha, Pritish; Harding, Gareth W; Maiko, Khumo; Hiller, Wolf; Pasch, Harald

    2012-11-23

    Liquid chromatography at critical conditions (LCCC) has been shown to be a powerful method for the separation of complex polymers regarding chemical composition, functionality, or molecular topology. LCCC has never been used, however, to separate polymers according to the degree of deuteration. This is a very challenging task since polymers shall be separated that are identical regarding molar mass, endgroups and chemical composition. In the present work, critical conditions were established in such a way that one component of a complex mixture elutes at critical conditions, whereas the other component shows size exclusion chromatography (SEC) behaviour. Blends of protonated (h) and deuterated (d) polystyrene (PS) were separated by LCCC at critical conditions of both h-PS and d-PS. Depending on the molar masses of the blend components, baseline separation could be achieved. In order to improve the separation further, comprehensive two-dimensional liquid chromatography was carried out on a number of model blends. In the first dimension LCCC was used, which separated the blends according to isotopic effects whereas in the second dimension the separation took place with respect to hydrodynamic volume. In order to further improve the separation of a number of blends a separation protocol was used where one component shows SEC conditions whereas the other component shows liquid adsorption chromatography (LAC) conditions. This separation protocol was achieved by varying the column temperature.

  1. Optimization of conditions for the single step IMAC purification of miraculin from Synsepalum dulcificum.

    PubMed

    He, Zuxing; Tan, Joo Shun; Lai, Oi Ming; Ariff, Arbakariya B

    2015-08-15

    In this study, the methods for extraction and purification of miraculin from Synsepalum dulcificum were investigated. For extraction, the effect of different extraction buffers (phosphate buffer saline, Tris-HCl and NaCl) on the extraction efficiency of total protein was evaluated. Immobilized metal ion affinity chromatography (IMAC) with nickel-NTA was used for the purification of the extracted protein, where the influence of binding buffer pH, crude extract pH and imidazole concentration in elution buffer upon the purification performance was explored. The total amount of protein extracted from miracle fruit was found to be 4 times higher using 0.5M NaCl as compared to Tris-HCl and phosphate buffer saline. On the other hand, the use of Tris-HCl as binding buffer gave higher purification performance than sodium phosphate and citrate-phosphate buffers in IMAC system. The optimum purification condition of miraculin using IMAC was achieved with crude extract at pH 7, Tris-HCl binding buffer at pH 7 and the use of 300 mM imidazole as elution buffer, which gave the overall yield of 80.3% and purity of 97.5%. IMAC with nickel-NTA was successfully used as a single step process for the purification of miraculin from crude extract of S. dulcificum.

  2. A simple and rapid ultra-high-performance liquid chromatography-tandem mass spectrometry method to determine plasma biotin in hemodialysis patients.

    PubMed

    Yagi, Shigeaki; Nishizawa, Manabu; Ando, Itiro; Oguma, Shiro; Sato, Emiko; Imai, Yutaka; Fujiwara, Masako

    2016-08-01

    A simple, rapid, and selective method for determination of plasma biotin was developed using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). After single-step protein precipitation with methanol, biotin and stable isotope-labeled biotin as an internal standard (IS) were chromatographed on a pentafluorophenyl stationary-phase column (2.1 × 100 mm, 2.7 μm) under isocratic conditions using 10 mm ammonium formate-acetonitrile (93:7, v/v) at a flow rate of 0.6 mL/min. The total chromatographic runtime was 5 min for each injection. Detection was performed in a positive electrospray ionization mode by monitoring selected ion transitions at m/z 245.1/227.0 and 249.1/231.0 for biotin and the IS, respectively. The calibration curve was linear in the range of 0.05-2 ng/mL using 300 μL of plasma. The intra- and inter-day precisions were all <7.1%. The accuracy varied from -0.7 to 8.2%. The developed UHPLC-MS/MS method was successfully applied to determine plasma biotin concentrations in hemodialysis patients. Copyright © 2016 John Wiley & Sons, Ltd.

  3. Fast preparation of a highly efficient organic monolith via photo-initiated thiol-ene click polymerization for capillary liquid chromatography.

    PubMed

    Chen, Lianfang; Ou, Junjie; Liu, Zhongshan; Lin, Hui; Wang, Hongwei; Dong, Jing; Zou, Hanfa

    2015-05-15

    A novel organic monolith was firstly prepared in a UV-transparent fused-silica capillary by a single-step approach via photo-initiated thiol-ene click polymerization reaction of 1,2,4-trivinylcyclohexane (TVCH) and pentaerythriol tetra(3-mercaptopropionate) (4SH) within 10min. The effects of both composition of prepolymerization solution and polymerization time on the morphology and permeability of monolithic column were investigated in detail. Then, the optimal condition was acquired to fabricate a homogeneous and permeable organic monolith. The chemical groups of the monolithic column were confirmed by Fourier transform infrared spectroscopy (FT-IR). The SEM graphs showed the organic monolith possessed a uniform porous structure, which promotes the highest column efficiency of ∼133,000 plates per meter for alkylbenzenes at the linear velocity of 0.65mm/s in reversed-phase liquid chromatography. Finally, the organic monolithic column was further applied for separation of basic compounds, pesticides and EPA610, indicating satisfactory separation ability.

  4. Simultaneous determination of neonicotinoid insecticides in human serum and urine using diatomaceous earth-assisted extraction and liquid chromatography-tandem mass spectrometry.

    PubMed

    Yamamuro, Tadashi; Ohta, Hikoto; Aoyama, Mika; Watanabe, Daisuke

    2014-10-15

    A rapid and sensitive analytical method was developed for simultaneous determination of eight neonicotinoid insecticides (acetamiprid, clothianidin, dinotefuran, flonicamid, imidacloprid, nitenpyram, thiacloprid and thiamethoxam) and three specific metabolites of acetamiprid (N-desmethylacetamiprid, 5-(N-acetyl-N-methylaminomethyl)-2-chloropyridine and 5-(N-acetylaminomethyl)-2-chloropyridine) in human serum and urine. A diatomaceous earth-assisted extraction using Extrelut NT3 column with chloroform/2-propanol (3:1, v/v) as eluent was selected for the single step cleanup procedure for all the target compounds. Qualitative and quantitative analyses were conducted by liquid chromatography-tandem mass spectrometry with multiple reaction monitoring mode. The limits of detection and the limits of quantification of eleven compounds were in the ranges of 0.1-0.2ng/mL and 0.5-10ng/mL for serum, 0.1-1ng/mL and 1-10ng/mL for urine, respectively. The extraction recoveries were between 80.9% and 101.8% for serum samples, 91.9% and 106% for urine samples. The intra-day RSDs and the inter-day RSDs were less than 11.5% and 13.2% for serum, less than 8.3% and 8.8% for urine. The proposed procedure will be suitable for forensic investigations of human poisoning cases with neonicotinoid insecticides. This is the first report of simultaneous determination of eight neonicotinoids in serum and urine samples.

  5. Determination of N-methylcarbamate pesticides in vegetables by poly(methacrylic acid-co-ethylene glycol dimethacrylate) monolith microextraction coupled with high performance liquid chromatography.

    PubMed

    Ma, Huihui; Feng, Wei; Tian, Miaomiao; Jia, Qiong

    2013-06-15

    A simple, rapid and sensitive method for simultaneous determination of three N-methylcarbamate pesticides (carbaryl, pirimicarb, and isoprocarb) in vegetables was developed by coupling polymer monolith microextraction (PMME) to high-performance liquid chromatography (HPLC). A poly(methacrylic acid-co-ethylene glycol dimethacrylate) monolith was selected as the extraction medium for PMME. To achieve optimum extraction performance, several parameters were investigated, including desorption solvent, desorption flow rate, sample flow rate, sample volume, sample pH values, inorganic salt and organic solvent content of the sample solution. Under the optimum experimental conditions, the method provides an acceptable linearity (5-5000μg/kg), low limits of detection (0.36-2.6μg/kg), good precision (intra-day relative standard deviations<2.53%, inter-day relative standard deviations <6.36%). Finally, the developed method was successfully applied to the determination of N-methylcarbamate pesticides in vegetables, and the trueness was evaluated by recovery experiments. The obtained relative recoveries were in the range of 70.4-98.5%. This PMME method integrates sample extraction, purification, and preconcentration of analytes into one single step and it also has several advantages such as solvent-free extraction, small sample volume, high enrichment, convenience, and flexibility operation.

  6. Quantification of zolpidem in human plasma by high-performance liquid chromatography with fluorescence detection.

    PubMed

    Nirogi, Ramakrishna V S; Kandikere, Vishwottam N; Shrivasthava, Wishu; Mudigonda, Koteshwara

    2006-10-01

    A simple, reliable HPLC method with fluorescence detection (excitation 320 and emission 388 nm) was developed and validated for quantitation of zolpidem in human plasma. Following a single-step liquid-liquid extraction, the analyte and internal standard (quinine) were separated using an isocratic mobile phase on a reversed-phase C(18) column. The lower limit of quantitation was 1.8 ng/mL, with a relative standard deviation of less than 5%. A linear dynamic range of 1.8-288 ng/mL was established. This HPLC method was validated with between-batch and within-batch precision of 1.7-4.8 and 1.2-2.3%, respectively. The between-batch and within-batch accuracy was 95.3-100.4 and 95.5-102.7%, respectively. Frequently coadministered drugs did not interfere with the described methodology. Stability of zolpidem in plasma was excellent, with no evidence of degradation during sample processing (autosampler) and 30 days storage in a freezer. This validated method is simple and repeatable enough to be used in pharmacokinetic studies.

  7. General methodology for the estimation of common neutral urinary steroids by multi-columin liquid chromatography.

    PubMed

    Vestergaard, P; Sayegh, J F

    1978-01-01

    A method is described for the estimation of common neutral urinary steroids by multi-column liquid chromatography. Hydrolysis is performed in two steps: enzymatically, using beta-glucuronidase, followed by solvolysis. Initial short column chromatography separates the neutral steroids into three fractions according to polarity: 17-oxosteroids, corticosteriods less polar than cortolones, and cortolones and cortols. The cortolone, cortol fraction is oxidized and the different steroid groups are chromatographed on capillary aluminum oxide and silica gel columns. A computerized, spectrophotometric system is used for the quantitation procedure.

  8. Emerging approaches to estimate retention factors in high performance liquid chromatography.

    PubMed

    Bermúdez-Saldaña, José María; Escuder-Gilabert, Laura; Villanueva-Camañas, Rosa María; Medina-Hernández, María José; Sagrado, Salvador

    2005-11-11

    The retention factor is one of the most universally used parameters in chromatography. The errors associated with the conventional ways to determine the retention factor of compounds in liquid chromatography are studied and compared with those corresponding to new approaches. The later avoid the use of extra-column time and hold-up time values, which have proven to be tedious and ambiguous. Simulations and real data, used to examine the accuracy of four different approaches (two classic and two new), suggest that the new approaches could be considered more satisfactory than the classic ones.

  9. Rapid analysis of phentolamine by high-performance liquid chromatography.

    PubMed

    Webster, Gregory K; Lemmer, Robert R; Greenwald, Steven

    2003-02-01

    A rapid liquid chromatographic method is validated for the quantitative analysis of phentolamine. Phentolamine exists in three forms for this investigation: as a mesylate salt, hydrochloride salt, and free base. In solution, phentolamine dissociates from its salt and is chromatographed as free phentolamine. This validation confirms the analysis of each form, which is simply based upon molar mass differences encountered in weighing. As such, both the United States Pharmacopeia hydrochloride and mesylate standards are used throughout this validation to demonstrate this equivalency. The validation demonstrates that this method may be used to quantitate phentolamine, regardless of its salt form.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Separation and determination of homogenous fatty alcohol ethoxylates by liquid chromatography with mulitstage mass spectrometry.

    PubMed

    Zembrzuska, Joanna; Budnik, Irena; Lukaszewski, Zenon

    2014-07-01

    Alcohol ethoxylates (AEs) are a significant component of a stream of surfactants directed to the aquatic environment. The aim of this work was the investigation of the dependence of the analytical signals of homogeneous AE homologues on liquid chromatography with tandem mass spectrometry conditions, as well as the separation of AEs from the water matrix and, on this basis, the development of an analytical procedure suitable for the determination of AEs in environmental samples. Homogeneous homologues containing dodecyl moiety and 2-9 oxyethylene subunits were investigated. The analytical signals of the investigated homologues were optimized in terms of concentration of ammonium acetate in the mobile phase (optimum 5 mM) and a column temperature (optimum 35°C) of the liquid chromatography with tandem mass spectrometry system. A separation of AEs from the water matrix by liquid-liquid extraction (ethyl acetate, chloroform) or solid-phase extraction (C18 , styrene divinylbenzene, H-RX) was investigated. In a model investigation, the best recoveries (>90%) were obtained with a styrene divinylbenzene cartridge eluted with a 1:1 mixture of chloroform and methanol. However, much worse recoveries were obtained from the river water sample. Better results were obtained for liquid-liquid extraction with ethyl acetate. Recoveries of 62-80% were obtained for homologues having 4-9 oxyethylene subunits, at the lowest spike.

  15. Quantitative analysis of multiple components based on liquid chromatography with mass spectrometry in full scan mode.

    PubMed

    Xu, Min Li; Li, Bao Qiong; Wang, Xue; Chen, Jing; Zhai, Hong Lin

    2016-08-01

    Although liquid chromatography with mass spectrometry in full scan mode can obtain all the signals simultaneously in a large range and low cost, it is rarely used in quantitative analysis due to several problems such as chromatographic drifts and peak overlap. In this paper, we propose a Tchebichef moment method for the simultaneous quantitative analysis of three active compounds in Qingrejiedu oral liquid based on three-dimensional spectra in full scan mode of liquid chromatography with mass spectrometry. After the Tchebichef moments were calculated directly from the spectra, the quantitative linear models for three active compounds were established by stepwise regression. All the correlation coefficients were more than 0.9978. The limits of detection and limits of quantitation were less than 0.11 and 0.49 μg/mL, respectively. The intra- and interday precisions were less than 6.54 and 9.47%, while the recovery ranged from 102.56 to 112.15%. Owing to the advantages of multi-resolution and inherent invariance properties, Tchebichef moments could provide favorable results even in the situation of peaks shifting and overlapping, unknown interferences and noise signals, so it could be applied to the analysis of three-dimensional spectra in full scan mode of liquid chromatography with mass spectrometry.

  16. Separation of tocopherols by nano-liquid chromatography.

    PubMed

    Fanali, Salvatore; Camera, Emanuela; Chankvetadze, Bezhan; D'Orazio, Giovanni; Quaglia, Maria Giovanna

    2004-04-16

    Nanoliquid chromatography (nano-LC) was used for the separation of tocopherols (delta-, gamma-, alpha-TOH), alpha-tocopherol acetate (alpha-TOH-Ac) and an antioxidant compound, namely butylated hydroxytoluene (BHT) used to prevent TOHs autoxidation. The separation was carried out in a fused silica capillary of 100 microm I.D. and 375 microm O.D. packed in our laboratory with RP18 silica stationary phase of either 5- or 3-microm diameter (23-cm long). The mobile phase was composed by mixtures of methanol (MeOH), acetonitrile (MeCN) and water. Typical analyses time for the separation of all the five components of the mixture were 6-9 min depending on the composition of the mobile phase. Efficiency and resolution were strongly influenced by the particle diameter and the highest Rs and N/m values were observed using 3-microm RP18 particles. Experiments performed with capillaries packed with 3-microm RP18 particles provided good limit of detection (LOD) and limit of quantification (LOQ) (for delta-, gamma-TOH, alpha-TOH-Ac were 4 and 8 microg/ml, while for alpha-TOH were 6 and 10 microg/ml, respectively). The optimized method was applied to extracts of serum and pharmaceutical preparation containing alpha-TOH and alpha-TOH-Ac.

  17. Bridging the gap between gas and liquid chromatography.

    PubMed

    Gritti, Fabrice; Fogwill, Michael; Gilar, Martin; Jarrell, Joseph A

    2016-11-11

    The rapid and complete baseline separation of both volatile (C5 to C16 alkanes in gasoline or terpenes in plant extracts) and non-volatile (>C20 alkanes) organic compounds was achieved by combining (1) low-density fluid chromatography (LDFC) using carbon dioxide at elevated temperature (>90°C) and low pressure (1500psi) designed to increase the retention of the most volatile compounds and (2) high-vacuum technology (<10(-4)Torr) in order to preserve the maximum efficiency of short analytical columns (3.0mm×150mm packed with 1.8μm fully porous HSS-SB-C18 particles) when used in LDFC. The volatile compounds are eluted first under isobaric conditions (1500psi) in less than a minute followed by a linear gradient of the column back pressure (from 1500 to 3500psi in 5min) for the elution of the non-volatile compounds up to C40. The experimental results demonstrate that LDFC performed with short 3.0mm i.d. columns packed with sub-2μm particles and placed under adiabatic conditions enables the analysts to deliver a single, fast, and high-resolution separation of both volatile and non-volatile compounds.

  18. Coupling of nanoflow liquid chromatography to matrix-assisted laser desorption/ionization mass spectrometry: real-time liquid chromatography run mapping on a MALDI plate.

    PubMed

    Nägele, Edgar; Vollmer, Martin

    2004-01-01

    The major obstacle in the use of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) instruments in the analysis of complex proteome samples is the lack of a direct coupling of a highly resolving separation technique with the mass spectrometer itself. To overcome this drawback, a spotting device for capillary and nanoflow liquid chromatography (LC) with a special liquid deposition principle for lowest volumes was developed. The instrument is able to perform MALDI spotting in real time in order to deposit the LC run on the MALDI plate, and therefore couples the high resolution power of nano-RP-HPLC separation directly with MALDI-MS. This work describes the development and optimization of a method for spotting with online matrix addition, and illustrates its use in the analysis of a complex proteome sample.

  19. Monitoring of cefepime in human serum and plasma by micellar electrokinetic capillary chromatography: Improvement of sample preparation and validation by liquid chromatography coupled to mass spectrometry.

    PubMed

    Šestáková, Nela; Theurillat, Regula; Sendi, Parham; Thormann, Wolfgang

    2017-02-20

    Cefepime monitoring in deproteinized human serum and plasma by micellar electrokinetic capillary chromatography and liquid chromatography coupled to mass spectrometry in presence of other drugs is reported. For micellar electrokinetic capillary chromatography, sample preparation comprised dodecylsulfate protein precipitation at pH 4.5 using an increased buffer concentration compared to that of a previous assay and removal of hydrophobic compounds with dichloromethane. This provided robust conditions for cefepime analysis in the presence of sulfamethoxazole and thus enabled its determination in samples of patients that receive co-trimoxazole. The liquid chromatography assay is based upon use of a column with a pentafluorophenyl-propyl modified and multi-endcapped stationary phase and the coupling to electrospray ionization with a single quadrupole detector. The performances of both assays with multi-level internal calibration were assessed with calibration and control samples and both assays were determined to be robust. Cefepime levels monitored by micellar electrokinetic capillary chromatography in samples from patients that were treated with cefepime only and with cefepime and co-trimoxazole were found to compare well with those obtained by liquid chromatography coupled to mass spectrometry. Cefepime drug levels determined by micellar electrokinetic capillary chromatography could thereby be validated. This article is protected by copyright. All rights reserved.

  20. 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.

  1. [Determination of amygdalin in hawthorn by high performance liquid chromatography].

    PubMed

    Lü, Weifeng; Ding, Mingyu

    2005-09-01

    A suitable method for extraction of amygdalin from hawthorn has been established. At first, the lipophilic components were removed with petroleum ether by ultrasonic extraction. The amygdalin was then extracted by methanol in a Soxhlet's apparatus. For quantitation, a high performance liquid chromatographic method was developed by using a reversed-phase C18 column, mobile phase of methanol-water (15:85, v/v) and a detection wavelengh of 215 nm. It can be concluded that the content of amygdalin is higher in the seeds than that in the hawthorn powder without the seeds and the yield of amygdalin is higher in the hawthorn pieces than that in the hawthorn powder.

  2. In situ derivatization-ultrasound-assisted dispersive liquid-liquid microextraction for the determination of neurotransmitters in Parkinson's rat brain microdialysates by ultra high performance liquid chromatography-tandem mass spectrometry.

    PubMed

    He, Yongrui; Zhao, Xian-En; Zhu, Shuyun; Wei, Na; Sun, Jing; Zhou, Yubi; Liu, Shu; Liu, Zhiqiang; Chen, Guang; Suo, Yourui; You, Jinmao

    2016-08-05

    Simultaneous monitoring of several neurotransmitters (NTs) linked to Parkinson's disease (PD) has important scientific significance for PD related pathology, pharmacology and drug screening. A new simple, fast and sensitive analytical method, based on in situ derivatization-ultrasound-assisted dispersive liquid-liquid microextraction (in situ DUADLLME) in a single step, has been proposed for the quantitative determination of catecholamines and their biosynthesis precursors and metabolites in rat brain microdialysates. The method involved the rapid injection of the mixture of low toxic bromobenzene (extractant) and acetonitrile (dispersant), which containing commercial Lissamine rhodamine B sulfonyl chloride (LRSC) as derivatization reagent, into the aqueous phase of sample and buffer, and the following in situ DUADLLME procedure. After centrifugation, 50μL of the sedimented phase (bromobenzene) was directly injected for ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) detection in multiple reaction monitoring (MRM) mode. This interesting combination brought the advantages of speediness, simpleness, low matrix effects and high sensitivity in an effective way. Parameters of in situ DUADLLME and UHPLC-MS/MS conditions were all optimized in detail. The optimum conditions of in situ DUADLLME were found to be 30μL of microdialysates, 150μL of acetonitrile containing LRSC, 50μL of bromobenzene and 800μL of NaHCO3-Na2CO3 buffer (pH 10.5) for 3.0min at 37°C. Under the optimized conditions, good linearity was observed with LODs (S/N>3) and LOQs (S/N>10) of LRSC derivatized-NTs in the range of 0.002-0.004 and 0.007-0.015 nmol/L, respectively. It also brought good precision (3.2-12.8%, peak area CVs%), accuracy (94.2-108.6%), recovery (94.5-105.5%) and stability (3.8-8.1%, peak area CVs%) results. Moreover, LRSC derivatization significantly improved chromatographic resolution and MS detection sensitivity of NTs when compared with the

  3. [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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

    2015-10-09

    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.

  11. 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.

  12. Determination of acaricides in honey by high-performance liquid chromatography with photodiode array detection.

    PubMed

    Martel, Anne-Claire; Zeggane, Sarah

    2002-04-19

    Rapid analytical methods are described to control quality of honeys, concerning residues of acaricides applied in hives to prevent Varroa jacobsoni infestation. A liquid-liquid extraction with hexane-propanol-2-ammonia (60 ml:30 ml:0.28%) was used for the simultaneous analysis of coumaphos, bromopropylate, amitraz and fluvalinate. For thymol, one clean up on a solid-phase extraction C18 (500 mg, 6 ml) column was performed; for rotenone, a liquid extraction with dichloromethane was realised. Quantitative recoveries obtained with honey were satisfactory and were superior to 80%. All acaricides are identified by reversed-phase high-performance liquid chromatography with photodiode array detection. Quantification limits obtained were below maximal residue limits when these exist.

  13. 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.

  14. Liquid chromatography-thermospray mass spectrometry of DNA adducts formed with mitomycin C, porfiromycin and thiotepa.

    PubMed

    Musser, S M; Pan, S S; Callery, P S

    1989-07-14

    High-performance liquid chromatography (HPLC) and thermospray mass spectrometry were combined for the analysis of DNA adducts formed from the interaction of the anticancer drugs mitomycin C, porfiromycin and thiotepa with calf thymus DNA. The adducts formed from reaction of mitomycin C and porfiromycin with DNA were separated from unmodified nucleosides by HPLC on a C18 column and identified by thermospray mass spectrometry. Thiotepa DNA adducts readily depurinated from DNA and were chromatographed and identified by thermospray liquid chromatography-mass spectrometry as the modified bases without the ribose moiety attached. The utility of thermospray mass spectrometry for the identification of microgram quantities of nucleoside adducts and depurinated base adducts of these anticancer drugs was demonstrated.

  15. 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

  16. 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.

  17. 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.

  18. Application of micellar liquid chromatography for the determination of antitumoral and antiretroviral drugs in plasma.

    PubMed

    Peris-Vicente, Juan; Casas-Breva, Inmaculada; Roca-Genovés, Pasqual; Esteve-Romero, Josep

    2014-01-01

    In micellar liquid chromatography, the mobile phase is made of a surfactant and, eventually, an alcohol. This article describes several methods to measure the concentration of antitumoral and antiretroviral drugs in plasma, utilizing micellar liquid chromatography. Samples can be injected after dilution with a micellar solution and filtration, because proteins and other endogenous compounds are solubilized in micellar medium. We will discuss the following optimized parameters: dilution ratio, type of column, detection conditions and mobile phase composition. This article will also cover the validation performed following the International Conference on Harmonization guidelines and the results reported in the literature, indicating that the methods are useful for the routine analysis of plasma samples for clinical purposes.

  19. 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

  20. Pyrolysis gas-liquid chromatography of the genus Bacillus: effect of growth media on pyrochromatogram reproducibility.

    PubMed

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

    1977-04-01

    Pyrolysis gas-liquid chromatography was performed on dried Bacillus microorganisms to evaluate the effects of growth media. Six cultures of Bacillus and six lot numbers of Trypticase soy agar (BBL) were used to test the hypothesis that a microorganism grown on various lot numbers of the same chromatogram. Also tested was the effect of three different media on chromatogram reproduction using the same six cultures. Results show little or no differences observed between the chromatograms of the individual Bacillus spp. grown on the six lot numbers of Trypticase soy agar. When chromatograms of the three different media were compared, several differences were observed, particularly in the areas most characteristic of individual species. Pryolysis gas-liquid chromatography can be a useful tool for the characterization or identification of the genus Bacillus if the chromatographic and cultural conditions are maintained.

  1. Ultrahigh-pressure liquid chromatography: fundamental aspects of compression and decompression heating.

    PubMed

    Gilpin, R K; Zhou, W

    2008-03-01

    Ultrahigh-pressure liquid chromatography is an emerging technique for carrying out rapid and highly efficient separations. Unfortunately, one of the simplifying assumptions made in conventional high-performance liquid chromatography, incompressibility of the mobile phase, is not valid when higher and higher pressures are used. Rather, both compression and decompression of the eluent must be considered in terms of both heating and changes in the solvent's structure. The first of these problems, eluent heating during the compression and decompression cycles, which occurs in the pump and column, respectively, are considered in terms of a combined first principle-empirical approach that is solved (i.e., an analytic solution obtained from the resulting integral equation) using 0.01 Bar pressure steps. The approach is used to estimate compression and decompression heating for methanol and water.

  2. Atmospheric pressure chemical ionisation liquid chromatography/mass spectrometry of bacteriochlorophylls from Chlorobiaceae: characteristic fragmentations.

    PubMed

    Airs, Ruth L; Keely, Brendan J

    2002-01-01

    Atmospheric pressure chemical ionisation liquid chromatography/mass spectrometry/mass spectrometry (APCI-LC/MS/MS) has been applied to the study of bacteriochlorophylls c, d, and e of phototrophic prokaryotes. Cultures of Chlorobiaceae containing bacteriochlorophyll c, d or e were examined using a high-resolution high-performance liquid chromatography (HPLC) method and APCI-LC/MS/MS employing post-column addition of formic acid. The results reveal complex distributions of bacteriochlorophyll homologues, with some closely eluting species giving isobaric protonated molecules. On-line LC/MS/MS studies reveal characteristic fragment ions for bacteriochlorophylls c, d, and e. Fragmentations involving loss of the extended alkyl substituents that are unique to bacteriochlorophylls c, d and e and their derivatives have been rationalised by studying the phaeophorbides and the results applied to the direct study of the bacteriochlorophylls.

  3. 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.…

  4. 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.

  5. Comparison between high-performance liquid chromatography and gas chromatography methods for fatty acid identification and quantification in potato crisps.

    PubMed

    Sanches-Silva, A; Rodríguez-Bernaldo de Quirós, A; López-Hernández, J; Paseiro-Losada, P

    2004-04-02

    A reversed-phase high performance liquid chromatographic (RP-HLPC) method was compared with a gas chromatography-flame ionization detection (GC-FID) method for determining fatty acids in potato crisps. Different extraction procedures were used. Fatty acids were quantified by linear regression. Both methods presented good precision (R.S.D. < or = 5.88%) and recovery (> or = 82.31%). The precision using HPLC method was slightly better than for GC-FID method. There was good agreement between the fatty acid composition of potato crisps analysed by both methods. For most purposes the HPLC method would be better. However, when more fatty acids need to be analysed, GC is a more suitable method.

  6. 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.

  7. 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.

  8. A Simple Robust Orthogonal Background Correction Method for Two-Dimensional Liquid Chromatography

    PubMed Central

    Filgueira, Marcelo R.; Castells, Cecilia; Carr, Peter W.

    2012-01-01

    Background correction is a very important step that must be done before peak detection or any quantification procedure. When successful, this step greatly simplifies such procedures and enhances the accuracy of quantification. In the past, much effort has been invested to correct drifting baseline in one dimensional chromatography. In fast online comprehensive two-dimensional liquid chromatography (LC×LC) coupled with diode array detector (DAD), the change in the refractive index (RI) of the mobile phase in very fast gradients causes extremely serious baseline disturbances. The method reported here can be combined with many of existing baseline correction methods for one dimensional (1D) chromatography in two dimensional (2D) liquid chromatography and recreate the background structure for further correction. When such methods are applied orthogonally to the second dimension (2D), the background correction is dramatically improved. It results in an almost zero mean background level and it provides better background correction than does a simple subtraction of a blank. Indeed, the method proposed does not require running a blank sample. PMID:22702415

  9. Vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction of biogenic amines in fermented foods before their simultaneous analysis by high-performance liquid chromatography.

    PubMed

    Donthuan, Jaruwan; Yunchalard, Sirinda; Srijaranai, Supalax

    2014-11-01

    A simple, rapid, sensitive, and environmentally friendly method, based on modified dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography was developed for the simultaneous determination of five biogenic amines in fermented food samples. Biogenic amines were derivatized with 9-fluorenylmethyl chloroformate, extracted by vortex-assisted surfactant-enhanced emulsification liquid-liquid microextraction, and then analyzed by high-performance liquid chromatography. Five biogenic amine compounds were separated within 30 min using a C18 column and gradient elution with acetonitrile and 1% acetic acid. Factors influencing the derivatization and extraction efficiency such as type and volume of extraction solvent, type, and concentration of surfactant, pH, salt addition, and vortex time were optimized. Under the optimum conditions, the method provided the enrichment factors in the range of 161-553. Good linearity was obtained from 0.002-0.5 mg/L for cadaverine and tyramine, 0.003-1 mg/L for tryptamine and histamine, and 0.005-1 mg/L for spermidine with coefficient of determination (R(2) ) > 0.992. The limits of detection ranged from 0.0010 to 0.0026 mg/L. The proposed method was successfully applied to analysis of biogenic amines in fermented foods such as fermented fish (plaa-som), wine and beer where good recoveries were obtained in the range of 83.2-112.5%

  10. Ultrasound-assisted dispersive liquid-liquid microextraction combined with high-performance liquid chromatography-fluorescence detection for sensitive determination of biogenic amines in rice wine samples.

    PubMed

    Huang, Ke-Jing; Wei, Cai-Yun; Liu, Wei-Li; Xie, Wan-Zhen; Zhang, Jun-Feng; Wang, Wei

    2009-09-18

    Ultrasound-assisted dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography-fluorescence detection was used for the extraction and determination of three biogenic amines including octopamine, tyramine and phenethylamine in rice wine samples. Fluorescence probe 2,6-dimethyl-4-quinolinecarboxylic acid N-hydroxysuccinimide ester was applied for derivatization of biogenic amines. Acetonitrile and 1-octanol were used as disperser solvent and extraction solvent, respectively. Extraction conditions including the type of extraction solvent, the volume of extraction solvent, ultrasonication time and centrifuging time were optimized. After extraction and centrifuging, analyte was injected rapidly into high-performance liquid chromatography and then detected with fluorescence. The calibration graph of the proposed method was linear in the range of 5-500 microg mL(-1) (octopamine and tyramine) and 0.025-2.5 microg mL(-1) (phenethylamine). The relative standard deviations were 2.4-3.2% (n=6) and the limits of detection were in the range of 0.02-5 ng mL(-1). The method was applied to analyze the rice wine samples and spiked recoveries in the range of 95.42-104.56% were obtained. The results showed that ultrasound-assisted dispersive liquid-liquid microextraction was a very simple, rapid, sensitive and efficient analytical method for the determination of trace amount of biogenic amines.

  11. 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.

  12. Liquid Chromatography-Tandem Mass Spectrometry to Define Sortase Cleavage Products.

    PubMed

    Duong, Andrew; Koteva, Kalinka; Sexton, Danielle L; Elliot, Marie A

    2016-01-01

    Sortase enzymes have specific endopeptidase activity, cleaving within a defined pentapeptide sequence at the C-terminal end of their protein substrates. Here, we describe how monitoring sortase cleavage activity can be achieved using peptide substrates. Peptide cleavage can be readily analyzed by liquid chromatography/tandem mass spectrometry (LC/MS/MS), which allows for the precise definition of cleavage sites. This technique could be used to analyze the peptidase activity of any enzyme, and identify sites of cleavage within any peptide.

  13. 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

  14. 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

  15. 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.

  16. High performance liquid chromatography of benzalkonium chlorides--variation in commercial preparations.

    PubMed

    Euerby, M R

    1985-03-01

    High performance liquid chromatography (HPLC) has been used to identify and determine the various alkyl benzyldimethylammonium chloride homologues (C10 to C16) present in commercial benzalkonium chloride preparations. The assay is especially suited for routine quality control work since it has proved to be quick and easily reproducible. It has been found that there can be a large degree of variation in the quality of differing benzalkonium chloride sources.

  17. High-Performance Liquid Chromatography (HPLC) Measurements of Phytoplankton Pigment Distributions of Ocean Waters

    DTIC Science & Technology

    1988-11-01

    coccolithophorids 19. ABSTRACT (CanMyw on rviosfe Inhcesway aM den*t byblock nmber) Until the application of high-performance liquid chromatography (HPLC) to... phycocyanin , has a maximum 0 01 absorption peak. The spectra for the 008 chlorophyll degradation products (chlo- 0.06 rophyllides, phaeophorbides and...phaeo- phytins) which are not shown in Figure z I have similar absorption maxima as their associated chlorophylls, 002 , Until the application of high

  18. 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.

  19. Steroid profiling by gas chromatography-mass spectrometry and high performance liquid chromatography-mass spectrometry for adrenal diseases.

    PubMed

    McDonald, Jeffrey G; Matthew, Susan; Auchus, Richard J

    2011-12-01

    The ability to measure steroid hormone concentrations in blood and urine specimens is central to the diagnosis and proper treatment of adrenal diseases. The traditional approach has been to assay each steroid hormone, precursor, or metabolite using individual aliquots of serum, each with a separate immunoassay. For complex diseases, such as congenital adrenal hyperplasia and adrenocortical cancer, in which the assay of several steroids is essential for management, this approach is time consuming and costly, in addition to using large amounts of serum. Gas chromatography/mass spectrometry profiling of steroid metabolites in urine has been employed for many years but only in a small number of specialized laboratories and suffers from slow throughput. The advent of commercial high-performance liquid chromatography instruments coupled to tandem mass spectrometers offers the potential for medium- to high-throughput profiling of serum steroids using small quantities of sample. Here, we review the physical principles of mass spectrometry, the instrumentation used for these techniques, the terminology used in this field and applications to steroid analysis.

  20. 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.

  1. Broad range analysis of endocrine disruptors and pharmaceuticals using gas chromatography and liquid chromatography tandem mass spectrometry.

    PubMed

    Trenholm, Rebecca A; Vanderford, Brett J; Holady, Janie C; Rexing, David J; Snyder, Shane A

    2006-12-01

    Endocrine disrupting compounds (EDCs) and pharmaceuticals and personal care products (PPCPs) have been globally detected in impacted natural waters. The detection of trace quantities of EDCs and PPCPs in the environment is of great concern since some of these compounds have known physiological responses at low concentrations. EDCs can have a wide range of polarities, acidic and basic moieties, and exist in trace quantities, which often requires numerous complex extractions, large sample collection volumes, and multiple instrumental analyses. A comprehensive method has been developed allowing for the analysis of 58 potential EDCs in various water matrices using a single solid-phase extraction (SPE) of a 1L sample with subsequent analyses using both gas chromatography and liquid chromatography, each coupled with tandem mass spectrometry (GC-MS/MS and LC-MS/MS). Instrument detection limits ranged between 0.12-7.5 pg with corresponding method reporting limits of 1-10 ng l(-1) in water. Recoveries for most compounds were between 50% and 112% with good reproducibility (RSD 6-22%).

  2. 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.

  3. Classification of natural resins by liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry using chemometric analysis.

    PubMed

    Rhourrhi-Frih, B; West, C; Pasquier, L; André, P; Chaimbault, P; Lafosse, M

    2012-09-21

    Twenty-six resins from six botanical sources belonging to the class Magnoliopsida were compared based on gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry data. The extracts were analysed by GC after silylation and by reversed phase LC combined with atmospheric pressure photoionisation (APPI) mass spectrometry. The chromatograms were re-organized in data matrices, where each sample was represented by a single column comprising 2755 observations (intensity, time, m/z) in GC-MS and 360 observations in LC-MS. A simple comparison of resin fingerprints was attempted by organizing data according to a three dimensional bubble chart (retention time against m/z where each point was a bubble which size represented the ion intensity) where it is possible to easily superimpose the fingerprints. Thus the common and different species can be easily observed enabling to classify the resins. Hierarchical cluster analysis based on characteristics of GC-MS and LC-MS profiles affords a complete description of the classes of the resins and shows that 26 resins are divided into five main clusters Commiphora mukul, Daniella oliveri, Gardenia gummifera, Canarium madagascariensis, Boswellia dalzielii and Boswellia serrata, respectively. In conclusion, the proposed method has been applied to three other resinous samples from the Burseraceae family to evaluate their alteration state.

  4. Isolation and purification of heroin from heroin street samples by preparative high performance liquid chromatography.

    PubMed

    Guo, Zhen; Zheng, Hui; Lu, Yanzhen; Wei, Yun

    2012-09-10

    The present study established a novel method using preparative high performance liquid chromatography to isolate and purify heroin·HCl from heroin street samples to be used as a reference standard. Different kinds of mobile phases and columns were used, ultimately the mobile phase consisting of hexane-isopropanol-methanol (65:28:7, v/v) and the SIL preparative column prepared in laboratory were selected as the final condition. Heroin was further purified by the drowning-out crystallization method using isopropanol-methanol (50:1, v/v) and hexane as drowning-out anti-solvents and salting-out agents, respectively. The purity was assessed by analytical high performance liquid chromatography and the confirmation of the chemical structure was performed by IR and NMR. About 110.7mg of heroin·HCl at a purity of over 99.52% was obtained from 180mg of heroin street samples which contained 156.15mg of heroin·HCl component by preparative high performance liquid chromatography. This method is suitable for preparing heroin standards in forensic science area.

  5. Multidimensional liquid chromatography for the determination of chiral coumarins and furocoumarins in Citrus essential oils.

    PubMed

    Dugo, Paola; Russo, Marina; Sarò, Mariagiovanna; Carnovale, Caterina; Bonaccorsi, Ivana; Mondello, Luigi

    2012-07-01

    In this work the enantiomeric distribution of chiral coumarins (meranzin and epoxyaurapten), and furocoumarins (oxypeucedanin, byakangelicol, and epoxybergamottin) in different Citrus essential oils (lemon, lime, grapefruit, and bitter orange) was determined by means of a heart-cutting multidimensional-liquid chromatography (MD-LC) system, equipped with a microsilica column in the first dimension in a combination to a cellulosic-based chiral column used in the second dimension. The normal phase-liquid chromatography-liquid chromatography (NP-LC-LC) instrumentation was equipped with a photodiode array detector and a multiport valve as interface. For method optimization and the determination of absolute configuration, natural compounds were isolated and racemic mixture was synthesized. The NP-LC-LC/PDA (where PDA is photodiode array) method provided a good baseline separation of chiral coumarins (meranzin and epoxyaurapten) and furocoumarins (epoxybergamottin and byakangelicol) present in cold-pressed Citrus essential oils without any sample pretreatment. Results obtained showed that for all the chiral compounds present in Citrus essential oils analyzed, there is always a clear prevalence of one of the two enantiomers, and do not appear influenced by the different geographical origin of the oils.

  6. Characterization of the efficiency of microbore liquid chromatography columns by van Deemter and kinetic plot analysis.

    PubMed

    Hetzel, Terence; Loeker, Denise; Teutenberg, Thorsten; Schmidt, Torsten C

    2016-10-01

    The efficiency of miniaturized liquid chromatography columns with inner diameters between 200 and 300 μm has been investigated using a dedicated micro-liquid chromatography system. Fully porous, core-shell and monolithic commercially available stationary phases were compared applying van Deemter and kinetic plot analysis. The sub-2 μm fully porous as well as the 2.7 μm core-shell particle packed columns showed superior efficiency and similar values for the minimum reduced plate heights (2.56-2.69) before correction for extra-column contribution compared to normal-bore columns. Moreover, the influence of extra-column contribution was investigated to demonstrate the difference between apparent and intrinsic efficiency by replacing the column by a zero dead volume union to determine the band spreading caused by the system. It was demonstrated that 72% of the intrinsic efficiency could be reached. The results of the kinetic plot analysis indicate the superior performance of the sub-2 μm fully porous particle packed column for ultra-fast liquid chromatography.

  7. A Simple and Accurate Equation for Peak Capacity Estimation in Two Dimensional Liquid Chromatography

    PubMed Central

    Li, Xiaoping; Stoll, Dwight R.; Carr, Peter W.

    2009-01-01

    Two dimensional liquid chromatography (2DLC) is a very powerful way to greatly increase the resolving power and overall peak capacity of liquid chromatography. The traditional “product rule” for peak capacity usually overestimates the true resolving power due to neglect of the often quite severe under-sampling effect and thus provides poor guidance for optimizing the separation and biases comparisons to optimized one dimensional gradient liquid chromatography. Here we derive a simple yet accurate equation for the effective two dimensional peak capacity that incorporates a correction for under-sampling of the first dimension. The results show that not only is the speed of the second dimension separation important for reducing the overall analysis time, but it plays a vital role in determining the overall peak capacity when the first dimension is under-sampled. A surprising subsidiary finding is that for relatively short 2DLC separations (much less than a couple of hours), the first dimension peak capacity is far less important than is commonly believed and need not be highly optimized, for example through use of long columns or very small particles. PMID:19053226

  8. Evaluation of a liquid chromatography method for quality control of methylated cyclodextrins.

    PubMed

    Fougère, L; Elfakir, C; Lafosse, M

    2013-02-15

    Halo C18 column (fused core particles) and Chromolith RP18 column (monolith) were evaluated in liquid chromatography in order to analyze methylated-β-cyclodextrins (Me-β-CD) with various degrees of substitution, DS such as the number of methyl groups per cyclodextrin ring. Chromolith RP18 enables a performing analysis of Me-β-CD with low DS but is not suitable for dimethyl-β-cyclodextrins (DM-β-CD). On the other hand, Halo C18 column allows an improved fingerprint of CDs having a DS from 4.9 up to a value major than 14 and avoiding the use of various chromatographic systems. Thus, liquid chromatography performed with this column and an evaporative light scattering detector can be used as a generic system for methylated CD analysis. Moreover, fused core particles of Halo C18 column enables a rapid analysis and liquid chromatography coupled with electrospray-mass spectrometry appears as a powerful tool to determine co-elution and to characterize various isomers of complex methylated-β-cyclodextrin mixtures.

  9. Recent development in liquid chromatography stationary phases for separation of Traditional Chinese Medicine components.

    PubMed

    Jin, Hongli; Liu, Yanfang; Guo, Zhimou; Wang, Jixia; Zhang, Xiuli; Wang, Chaoran; Liang, Xinmiao

    2016-10-25

    Traditional Chinese Medicine (TCM) is an ancient medical practice which has been used to prevent and cure diseases for thousands of years. TCMs are frequently multi-component systems with mainly unidentified constituents. The study of the chemical compositions of TCMs remains a hotspot of research. Different strategies have been developed to manage the significant complexity of TCMs, in an attempt to determine their constituents. Reversed-phase liquid chromatography (RPLC) is still the method of choice for the separation of TCMs, but has many problems related to limited selectivity. Recently, enormous efforts have been concentrated on the development of efficient liquid chromatography (LC) methods for TCMs, based on selective stationary phases. This can improve the resolution and peak capacity considerably. In addition, high-efficiency stationary phases have been applied in the analysis of TCMs since the invention of ultra high-performance liquid chromatography (UHPLC). This review describes the advances in LC methods in TCM research from 2010 to date, and focuses on novel stationary phases. Their potential in the separation of TCMs using relevant applications is also demonstrated.

  10. Comparison of liquid and supercritical fluid chromatography mobile phases for enantioselective separations on polysaccharide stationary phases.

    PubMed

    Khater, Syame; Lozac'h, Marie-Anne; Adam, Isabelle; Francotte, Eric; West, Caroline

    2016-10-07

    Analysis and production of enantiomerically pure compounds is a major topic of interest when active pharmaceutical ingredients are concerned. Enantioselective chromatography has become a favourite both at the analytical and preparative scales. High-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) are dominating the scene and are often seen as complementary techniques. Nowadays, for economic and ecologic reasons, SFC may be preferred over normal-phase HPLC (NPLC) as it allows significant reductions in solvent consumption. However, the transfer of NPLC methods to SFC is not always straightforward. In this study, we compare the retention of achiral molecules and separation of enantiomers under supercritical fluid (carbon dioxide with ethanol or isopropanol) and liquid normal-phase (heptane with ethanol or isopropanol) elution modes with polysaccharide stationary phases in order to explore the differences between the retention and enantioseparation properties between the two modes. Chemometric methods (namely quantitative structure-retention relationships and discriminant analysis) are employed to compare the results obtained on a large set of analytes (171 achiral probes and 97 racemates) and gain some understanding on the retention and separation mechanisms. The results indicate that, contrary to popular belief, carbon dioxide - solvent SFC mobile phases are often weaker eluents than liquid mobile phases. It appears that SFC and NPLC elution modes provide different retention mechanisms. While some enantioseparations are unaffected, facilitating the transfer between the two elution modes, other enantioseparations may be drastically different due to different types and strength of interactions contributing to enantioselectivity.

  11. EXTRACTION AND QUANTITATIVE ANALYSIS OF ELEMENTAL SULFUR FROM SULFIDE MINERAL SURFACES BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY. (R826189)

    EPA Science Inventory

    A simple method for the quantitative determination of elemental sulfur on oxidized sulfide minerals is described. Extraction of elemental sulfur in perchloroethylene and subsequent analysis with high-performance liquid chromatography were used to ascertain the total elemental ...

  12. Surveillance of the Army’s Propellant Stockpile: Analysis of Stabilizer Content by High Performance Liquid Chromatography

    DTIC Science & Technology

    1990-10-01

    high performance liquid chromatography to monitor the level of stabilizer and its daughter products in propellant. Three of those methods are presented along with statistics and some comments about their

  13. Single-step conversion of cellulose to 5-hydroxymethylfurfural (HMF), a versatile platform chemical

    SciTech Connect

    Su, Yu; Brown, Heather M.; Huang, Xiwen; Zhou, Xiao Dong; Amonette, James E.; Zhang, Z. Conrad

    2009-06-20

    The ability to use cellulosic biomass as feedstock for the production of fuels and chemicals currently derived from petroleum depends critically on the development of effective low-temperature processes. While HMF, as a versatile platform chemical suitable for use in polymer synthesis or production of liquid biofuels, can currently be made from fructose and glucose, synthesis of HMF directly from raw natural cellulose represents the last major barrier toward the development of a sustainable HMF platform. Here we report an unprecedented single-step pathway that depolymerizes cellulose rapidly under mild conditions and converts the resulting glucose to hydroxymethylfurfural (HMF). A pair of metal chlorides (CuCl2 and CrCl2) dissolved in 1-ethyl-3-methylimidazolium chloride at temperatures of 80-120°C catalyzes cellulose depolymerization and the subsequent glucose conversion to HMF with 95% selectivity among recoverable products (at 56% HMF yield). Cellulose depolymerization, which can also be catalyzed by other metalchloride pairs such as CuCl2 paired with PdCl2, CrCl3, or FeCl3, occurs at a rate that is more than one order of magnitude faster than conventional acid-catalyzed hydrolysis. In contrast, single-metal chlorides at the same total loading showed low activity under similar conditions. Mechanistic studies suggest that the C2 hydrogen of the imidazolium ring is activated by the paired metal-chloride catalysts.

  14. 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…

  15. 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.

  16. 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.

  17. Analysis of macrolide antibiotics, using liquid chromatography-mass spectrometry, in food, biological and environmental matrices.

    PubMed

    Wang, Jian

    2009-01-01

    Macrolides are a group of antibiotics that have been widely used in human medical and veterinary practices. Analysis of macrolides and related compounds in food, biological, and environmental matrices continue to be the focus of scientists for the reasons of food safety, pharmacokinetic studies, and environmental concerns. This article presents an overview on the primary biological properties of macrolides and their associated analytical issues, including extraction, liquid chromatography-mass spectrometry (LC-MS), method validation, and measurement uncertainty. The main techniques that have been used to extract macrolides from various matrices are solid-phase extraction and liquid-liquid extraction. Conventional liquid chromatography (LC) with C18 columns plays a dominant role for the determination of macrolides, whereas ultra-performance liquid chromatography (UPLC) along with sub-2 microm particle C18 columns reduces run time and improves sensitivity. Mass spectrometry (MS), serving as a universal detection technique, has replaced ultraviolet (UV), fluorometric, and electrochemical detection for multi-macrolide analysis. The triple-quadrupole (QqQ), quadrupole ion trap (QIT), triple-quadrupole linear ion trap, time-of-flight (TOF), and quadrupole time-of-flight (QqTOF) mass spectrometers are current choices for the determination of macrolides, including quantification, confirmation, identification of their degradation products or metabolites, and structural elucidation. LC or UPLC coupled to a triple-quadrupole mass spectrometer operated in the multiple-reaction monitoring (MRM) mode (LC/MS/MS) is the first choice for quantification. UPLC-TOF or UPLC-QqTOF has been recognized as an emerging technique for accurate mass measurement and unequivocal identification of macrolides and their related compounds.

  18. 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.

  19. Analysis of aromatic amines in water samples by liquid-liquid-liquid microextraction with hollow fibers and high-performance liquid chromatography.

    PubMed

    Zhao, Limian; Zhu, Lingyan; Lee, Hian Kee

    2002-07-19

    Liquid-liquid-liquid microextraction (LLLME) with hollow fibers in high-performance liquid chromatography (HPLC) has been applied as a rapid and sensitive quantitative method for the detection of four aromatic amines (3-nitroaniline, 4-chloroaniline, 4-bromoaniline and 3,4-dichloroaniline) in environmental water samples. The preconcentration procedure was induced by the pH difference inside and outside the hollow fiber. The target compounds were extracted from 4-ml aqueous sample (donor solution, pH approximately 13) through a microfilm of organic solvent (di-n-hexyl ether), immobilized in the pores of a hollow fiber (1.5 cm length x 0.6 mm I.D.), and finally into 4 microl of acid acceptor solution inside the fiber. After a prescribed period of time, the acceptor solution inside the fiber was withdrawn into the microsyringe and directly injected into the HPLC system for analysis. Factors relevant to the extraction procedure were studied. Up to 500-fold enrichment of analytes could be obtained under the optimized conditions (donor solution: 0.1 M sodium hydroxide solution with 20% sodium chloride and 2% acetone; organic phase: di-n-hexyl ether; acceptor solution: 0.5 M hydrochloric acid and 500 mM 18-crown-6 ether; extraction time of 30 min; stirring at 1,000 rev./min). The procedure also served as a sample clean-up step. The influence of humic acid on the extraction efficiency was also investigated, and more than 85% relative recoveries of the analytes at two different concentrations (20 and 100 microg/l) were achieved at various concentration of humic acid. This technique is a low cost, simple and fast approach to the analysis of polar compounds in aqueous samples.

  20. Liquid-liquid-liquid microextraction with automated movement of the acceptor and the donor phase for the extraction of phenoxyacetic acids prior to liquid chromatography detection.

    PubMed

    Chen, Chung-Chiang; Melwanki, Mahaveer B; Huang, Shang-Da

    2006-02-03

    A simple liquid-liquid-liquid microextraction with automated movement of the acceptor and the donor phase (LLLME/AMADP) technique is described for the quantitative determination of five phenoxyacetic acids in water using a disposable and ready to use hollow fiber. The target compounds were extracted from the acidified sample solution (donor phase) into the organic solvent residing in the pores of the hollow fiber and then back extracted into the alkaline solution (acceptor phase) inside the lumen of the hollow fiber. The fiber was held by a conventional 10-microl syringe. The acceptor phase was sandwiched between the plunger and a small volume of the organic solvent (microcap). The acceptor solution was repeatedly moved in and out of the hollow fiber assisted by a programmable syringe pump. This repeated movement provides a fresh acceptor phase to come in-contact with the organic phase and thus enhancing extraction kinetics leading to high enrichment of the analytes. The microcap separates the aqueous acceptor phase and the donor phase in addition of being partially responsible for mass transfer of the analytes from donor solution (moving in and out of the hollow fiber from the open end of the fiber) to the acceptor solution. Separation and quantitative analyses were then performed using liquid chromatography (LC) with ultraviolet (UV) detection at 280 nm. Various parameters affecting the extraction efficiency viz. type of organic solvent used for immobilization in the pores of the hollow fiber, extraction time, stirring speed, effect of sodium chloride, and concentration of donor and acceptor phases were studied. Repeatability (RSD, 3.2-7.4%), correlation coefficient (0.996-0.999), detection limit (0.2-2.8 ng ml(-1)) and enrichment factors (129-240) were also investigated. Relative recovery (87-101%) and absolute recoveries (4.6-13%) have also been calculated. The developed method was applied for the analysis of river water.

  1. 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.

  2. Ionic liquid-based dispersive liquid-liquid microextraction followed high-performance liquid chromatography for the determination of organophosphorus pesticides in water sample.

    PubMed

    He, Lijun; Luo, Xianli; Xie, Hongxue; Wang, Chunjian; Jiang, Xiuming; Lu, Kui

    2009-11-23

    Using 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)MIM][PF(6)]) ionic liquid as extraction solvent, organophosphorus pesticides (OPPs) (parathion, phoxim, phorate and chlorpyifos) in water were determined by dispersive liquid-liquid microextraction (DLLME) combined with high-performance liquid chromatography (HPLC). The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of [C(8)MIM][PF(6)] dispersed entirely into sample solution with the help of disperser solvent (methanol). Parameters including extraction solvent and its volume, disperser solvent and its volume, extraction time, centrifugal time, salt addition, extraction temperature and sample pH were investigated and optimized. Under the optimized conditions, up to 200-fold enrichment factor of analytes and acceptable extraction recovery (>70%) were obtained. The calibration curves were linear in the concentration range of 10.5-1045.0 microg L(-1) for parathion, 10.2-1020.0 microg L(-1) for phoxim, 54.5-1089.0 microg L(-1) for phorate and 27.2-1089.0 microg L(-1) for chlorpyifos, respectively. The limits of detection calculated at a signal-to-noise ratio of 3 were in the range of 0.1-5.0 microg L(-1). The relative standard deviations for seven replicate experiments at 200 microg L(-1) concentration level were less than 4.7%. The proposed method was applied to the analysis of four different sources water samples (tap, well, rain and Yellow River water) and the relative recoveries of spiked water samples are 99.9-115.4%, 101.8-113.7% and 87.3-117.6% at three different concentration levels of 75, 200 and 1000 microg L(-1), respectively.

  3. Method and apparatus for single-stepping coherence events in a multiprocessor system under software control

    DOEpatents

    Blumrich, Matthias A.; Salapura, Valentina

    2010-11-02

    An apparatus and method are disclosed for single-stepping coherence events in a multiprocessor system under software control in order to monitor the behavior of a memory coherence mechanism. Single-stepping coherence events in a multiprocessor system is made possible by adding one or more step registers. By accessing these step registers, one or more coherence requests are processed by the multiprocessor system. The step registers determine if the snoop unit will operate by proceeding in a normal execution mode, or operate in a single-step mode.

  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. 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).

  6. 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.

  7. Expression and Single-step Purification of GRA8 Antigen of Toxoplasma gondii in Escherichia coli

    PubMed Central

    Babaie, Jalal; Miri, Mandana; Sadeghiani, Ghazaleh; Zare, Mehrak; Khalili, Ghader; Golkar, Majid

    2011-01-01

    Diagnosis of Toxoplasma gondii (T.gondii) infection is of great medical importance especially for pregnant women and immunosuppressed patients. Numerous studies have shown that the recombinant production of several toxoplasma antigens, including dense granule antigens (GRAs) has a great potential as diagnostic reagents. Previous studies reported expression of amino terminal GRA8 protein in fusion with large tags. In the present study, we produced truncated GRA8 (GRA8), excluded from the signal peptide and C-terminal transmembrane domain, with a short fusion tag in Escherichia coli (E.coli). GRA8 was purified using an optimized single-step Immobilized Metal ion Affinity Chromatography (IMAC). The purity and yield of GRA8 was highest at pH = 9.25. At this pH, 13.6 mg of GRA8 was obtained with the purity of 97.97%. Immunogenicity of the protein was evaluated in Western blot analysis showing the serum sample from a rabbit immunized with GRA8 recognized a single antigen of T.gondii tachyzoite at the expected molecular weight of native GRA8. To diagnosis acute toxoplasma infection in pregnant women, an indirect immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) was developed using GRA8 resulting in a test specificity and sensitivity of 97.1% and 60.6%, respectively. These results demonstrated that immunogenic GRA8 can be produced in fusion with a short tag and purified near to homogeneity using an optimized IMAC. GRA8-IgM-ELISA was useful for detection of acute toxoplasma infection. PMID:23407862

  8. Single-step affinity purification of enzyme biotherapeutics: a platform methodology for accelerated process development.

    PubMed

    Brower, Kevin P; Ryakala, Venkat K; Bird, Ryan; Godawat, Rahul; Riske, Frank J; Konstantinov, Konstantin; Warikoo, Veena; Gamble, Jean

    2014-01-01

    Downstream sample purification for quality attribute analysis is a significant bottleneck in process development for non-antibody biologics. Multi-step chromatography process train purifications are typically required prior to many critical analytical tests. This prerequisite leads to limited throughput, long lead times to obtain purified product, and significant resource requirements. In this work, immunoaffinity purification technology has been leveraged to achieve single-step affinity purification of two different enzyme biotherapeutics (Fabrazyme® [agalsidase beta] and Enzyme 2) with polyclonal and monoclonal antibodies, respectively, as ligands. Target molecules were rapidly isolated from cell culture harvest in sufficient purity to enable analysis of critical quality attributes (CQAs). Most importantly, this is the first study that demonstrates the application of predictive analytics techniques to predict critical quality attributes of a commercial biologic. The data obtained using the affinity columns were used to generate appropriate models to predict quality attributes that would be obtained after traditional multi-step purification trains. These models empower process development decision-making with drug substance-equivalent product quality information without generation of actual drug substance. Optimization was performed to ensure maximum target recovery and minimal target protein degradation. The methodologies developed for Fabrazyme were successfully reapplied for Enzyme 2, indicating platform opportunities. The impact of the technology is significant, including reductions in time and personnel requirements, rapid product purification, and substantially increased throughput. Applications are discussed, including upstream and downstream process development support to achieve the principles of Quality by Design (QbD) as well as integration with bioprocesses as a process analytical technology (PAT).

  9. Multimycotoxin analysis in water and fish plasma by liquid chromatography-tandem mass spectrometry.

    PubMed

    Tolosa, J; Font, G; Mañes, J; Ferrer, E

    2016-02-01

    High performance liquid chromatography-mass spectrometry was used for the determination of 15 mycotoxins in water and fish plasma samples, including aflatoxins, fumonisins, ochratoxin A, sterigmatocistin, fusarenon-X and emerging Fusarium mycotoxins. In this work, dispersive liquid-liquid microextraction (DLLME) was assessed as a sample treatment for the simultaneous extraction of mycotoxins. Results showed differences in recovery assays when different extraction solvents were employed. Ethyl acetate showed better recoveries for the major part of mycotoxins analyzed, except for aflatoxins B2, G1 and G2, which showed better recoveries when employing chloroform as extractant solvent. Fumonisins and beauvericin exhibited low recoveries in both water and plasma. This method was validated according to guidelines established by European Commission and has shown to be suitable to be applied in dietary and/or toxicokinetic studies in fish where is necessary to check mycotoxin contents in rearing water and fish plasma.

  10. Determination of prostaglandin analogs in cosmetic products by high performance liquid chromatography with tandem mass spectrometry.

    PubMed

    Wittenberg, James B; Zhou, Wanlong; Wang, Perry G; Krynitsky, Alexander J

    2014-09-12

    A method was developed and validated for the determination of 16 prostaglandin analogs in cosmetic products. The QuEChERS (Quick, Easy, Cheap, Efficient, Rugged, Safe) liquid-liquid extraction method, typically used for pesticide residue analysis, was utilized as the sample preparation technique. The prostaglandin analogs were chromatographically separated and quantified using high performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). Thirty-one cosmetic products were surveyed, and 13 products were determined to contain a prostaglandin analog with amounts ranging from 27.4 to 297μg/g. The calculated concentrations for the cosmetic products were in a similar range when compared to the concentrations of three different prostaglandin analog-containing prescription products.

  11. Glucaminium ionic liquid-functionalized stationary phase for the separation of nucleosides in hydrophilic interaction chromatography.

    PubMed

    Jiang, Qiong; Zhang, Mingliang; Wang, Xusheng; Guo, Yong; Qiu, Hongdeng; Zhang, Shusheng

    2015-10-01

    A glucaminium-based ionic liquid stationary phase was prepared via facile epoxy-amine reaction and subsequent quaternization. Successful immobilization of glucaminium-based ionic liquid onto silica surface was validated by elemental analysis and infrared spectroscopy. The new stationary phase was evaluated for the separation of nucleosides in hydrophilic interaction liquid chromatography (HILIC). Effects of various factors, such as acetonitrile concentration, salt concentration, pH value, as well as column temperature, on the chromatographic behavior toward nucleosides were studied in detail. The results indicated that this new stationary phase can be used for separation of water-soluble polar substances in HILIC mode. The retention of solutes on the stationary phase was influenced by a mixed-mode retention mechanism with a combination of adsorptive and partitioning interactions.

  12. Ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction for the separation and determination of estrogens in water samples by high-performance liquid chromatography with fluorescence detection.

    PubMed

    Zhang, Rui; Wang, Chuanliu; Yue, Qiaohong; Zhou, Tiecheng; Li, Na; Zhang, Hanqi; Hao, Xiaoke

    2014-11-01

    An ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction method was proposed for the extraction and concentration of 17-α-estradiol, 17-β-estradiol-benzoate, and quinestrol in environmental water samples by high-performance liquid chromatography with fluorescence detection. 1-Hexyl-3-methylimidazolium tetrafluoroborate was applied as foaming agent in the foam flotation process and dispersive solvent in microextraction. The introduction of the ion-pairing and salting-out agent NH4 PF6 was beneficial to the improvement of recoveries for the hydrophobic ionic liquid phase and analytes. Parameters of the proposed method including concentration of 1-hexyl-3-methylimidazolium tetrafluoroborate, flow rate of carrier gas, floatation time, types and concentration of ionic liquids, salt concentration in samples, extraction time, and centrifugation time were evaluated. The recoveries were between 98 and 105% with relative standard deviations lower than 7% for lake water and well water samples. The isolation of the target compounds from the water was found to be efficient, and the enrichment factors ranged from 4445 to 4632. This developing method is free of volatile organic solvents compared with regular extraction. Based on the unique properties of ionic liquids, the application of foam floatation, and dispersive liquid-liquid microextraction was widened.

  13. Screening anti-tumor compounds from Ligusticum wallichii using cell membrane chromatography combined with high-performance liquid chromatography and mass spectrometry.

    PubMed

    Zhang, Tao; Ding, Yuanyuan; An, Hongli; Feng, Liuxin; Wang, Sicen

    2015-07-14

    Tyrosine 367 Cysteine-fibroblast growth factor receptor 4 cell membrane chromatography combined with high-performance liquid chromatography and mass spectrometry was developed. Tyrosine 367 Cysteine-HEK293 cells were used as cell membrane stationary phase. Specificity and reproducibility of the cell membrane chromatography was evaluated using 1-tert-butyl-3-{2-[4-(diethylamino)butylamino]-6-(3,5-dimethoxyphenyl)pyrido[2,3-d]pyrimidin-7-yl}urea, Nimodipine and dexamethasone acetate. Then, anti-tumor components acting on Tyrosine 367 Cysteine-fibroblast growth factor receptor 4 were screened and identified from extracts of Ligusticum wallichii. Components from the extract were retained on the cell membrane chromatographic column. The retained fraction was directly eluted into high-performance liquid chromatography with mass spectrometry system for separation and identification. Finally, Levistolide A was identified as an active component from Ligusticum wallichii extracts. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide-formazan colorimetric assay revealed that Levistolide A inhibits proliferation of overexpressing the mutated receptor cells with dose-dependent manner. Phosphorylation of fibroblast growth factor receptor 4 was also decrease under Levistolide A treatment. Flex dock simulation verified that Levistolide A could bind with the tyrosine kinase domain of fibroblast growth factor receptor 4. Therefore, Levistolide A screened by the cell membrane chromatography combined with high-performance liquid chromatography and mass spectrometry can arrest cell growth. In conclusion, the two-dimensional high-performance liquid chromatography method can screen and identify potential anti-tumor ingredients which specifically act on the tyrosine kinase domain of the mutated fibroblast growth factor receptor 4. This article is protected by copyright. All rights reserved.

  14. 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.

  15. 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…

  16. Home-made online hyphenation of pressurized liquid extraction, turbulent flow chromatography, and high performance liquid chromatography, Cistanche deserticola as a case study.

    PubMed

    Song, Qingqing; Li, Jun; Liu, Xiao; Zhang, Yuan; Guo, Liping; Jiang, Yong; Song, Yuelin; Tu, Pengfei

    2016-03-18

    Incompatibility between the conventional pressurized liquid extraction (PLE) devices and high performance liquid chromatography (HPLC) extensively hinders direct and green chemical analysis of herbal materials. Herein, a facile PLE module was configured, and then it was online hyphenated with HPLC via a turbulent flow chromatography (TFC) column. Regarding PLE module, a long PEEK tube (0.13 × 1000 mm) was employed to generate desired pressure (approximately 13.0 MPa) when warm acidic water (70 °C) was delivered as extraction solvent at a high flow rate (2.5 mL/min), and a hollow guard column (3.0 × 4.0 mm) was implemented to hold crude materials. Effluent was collected from the outlet of PEEK tube, concentrated, and subjected onto HPLC coupled with hybrid ion trap-time of flight mass spectrometer to assess the extraction efficiency and also to profile the chemical composition of Cistanche deserticola (CD) that is honored as "Ginseng of the desert". Afterwards, a TFC column was introduced to accomplish online transmission of low molecule weight components from PLE module to HPLC coupled with diode array detection, and two electronic 6-port/2-channel valves were in charge of alternating the whole system between extraction (0-3.0 min) and elution (3.0-35.0 min) phases. Quantitative method was developed and validated for simultaneous determination of eight primary phenylethanoid glycosides in CD using online PLE-TFC-HPLC. All findings demonstrated that the home-made platform is advantageous at direct chemical analysis, as well as time-, solvent-, and material-savings, suggesting a robust tool for chemical fingerprinting of herbs.

  17. Determination of Alternaria mycotoxins in wine and juice using ionic liquid modified countercurrent chromatography as a pretreatment method followed by high-performance liquid chromatography.

    PubMed

    Fan, Chen; Cao, Xueli; Liu, Man; Wang, Wei

    2016-03-04

    Alternariol (AOH), alternariol monomethyl ether (AME), and tenuazonic acid (TeA) are some of the main Alternaria mycotoxins that can be found as contaminants in food materials. The objective of this study was to develop a pretreatment method with countercurrent chromatography (CCC) for enrichment and cleanup of trace Alternaria mycotoxins in food samples prior to high-performance liquid chromatography (HPLC) analysis. An Analytical CCC instrument with a column volume 22.5mL was used, and a two-phase solvent system composed of ethyl acetate and water modified with 6% [HOOMIM][Cl] in mass to volume ratio was selected. Under the optimized CCC operation conditions, trace amounts of AOH, AME, and TeA in large volume of liquid sample were efficiently extracted and enriched in the stationary phase, and then eluted out just by reversing the stationary phase as mobile phase in the opposite flowing direction tail-to-head. The enrichment and elution strategies are unique and can be fulfilled online with high enrichment factors (87-114) and high recoveries (81.14-110.94%). The method has been successively applied to the determination of Alternaria mycotoxins in real apple juice and wine samples with the limits of detection (LOD) in the range of 0.03-0.14μgL(-1). Totally 12 wine samples and 15 apple juice samples from the local market were analyzed. The detection rate of AOH and AME in both kinds of the samples were more than 50%, while TeA was found in relatively high level of 1.75-49.61μgL(-1) in some of the apple juice samples. The proposed method is simple, rapid, and sensitive and could also be used for the analysis and monitoring of Alternaria mycotoxin in other food samples.

  18. Liquid-phase microextration combined with liquid chromatography-electrospray tandem mass spectrometry for detecting diuretics in urine.

    PubMed

    Tsai, Tzu-Feng; Lee, Maw-Rong

    2008-05-15

    Trace amounts of diuretics were determined in human urine by hollow fiber liquid-phase microextraction (LPME) combined with liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) in this study. Chromatography was performed on a C(8) reversed-phase column. A 25 microL n-octanol was used to extract analytes in urine. Extraction was optimized using a pH 2 solution spiked with 0.15 g/mL NaCl for 40 min at 40 degrees C with 1010 rpm stirring. The limits of detection of diuretics in urine were 0.3-6.8 ng/mL, and linearity range was 1-1000 ng/mL. Recoveries of spiked 50 ng/mL diuretics were 97.7-102.5%. The intra-day precision and inter-day precision were 3-18% and 4-21%, respectively. The diuretics concentration profiles in patient urine were also determined. The results of this study reveal the adequacy of LPME-LC-MS/MS method for analyzing diuretics in urine and quantification limits exceed World Anti-Doping Agency requirements.

  19. Improved sensitivity gas chromatography-mass spectrometry determination of parabens in waters using ionic liquids.

    PubMed

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

    2016-01-01

    A new procedure for the introduction of ionic liquid samples in gas chromatography (GC) is proposed. This procedure, based on microvial insert thermal desorption, allows the direct analysis of the compounds preconcentrated by ionic liquid based liquid-liquid microextraction (IL-LLME) using the combination of a thermal desorption unit (TDU) and a programmed temperature vaporization injector (PTV). Two different IL-LLME methodologies, one based on the formation of a microdroplet emulsion by dispersive liquid-liquid microextraction (DLLME) and other through ultrasound-assisted emulsification microextraction (USAEME) were studied and evaluated. IL-DLLME proved advantageous and consequently, it was adopted for preconcentration purposes. This easy to apply approach was used for the determination of five parabens (methyl-, ethyl-, propyl-, butyl- and isobutyl paraben) in swimming pool waters, after in situ acetylation. The optimized conditions of TDU/PTV allowed the analytes contained in 20 µL of the enriched IL to be transferred to the capillary column. Quantification of the samples was carried out against aqueous standards, and quantification limits of between 4.3 and 8.1 ng L(-1) were obtained, depending on the compound. Concentrations of between 9 and 47 ng L(-1) for some analytes were obtained in the analysis of ten samples.

  20. Analysis of trace dicyandiamide in stream water using solid phase extraction and liquid chromatography UV spectrometry.

    PubMed

    Qiu, Huidong; Sun, Dongdi; Gunatilake, Sameera R; She, Jinyan; Mlsna, Todd E

    2015-09-01

    An improved method for trace level quantification of dicyandiamide in stream water has been developed. This method includes sample pretreatment using solid phase extraction. The extraction procedure (including loading, washing, and eluting) used a flow rate of 1.0mL/min, and dicyandiamide was eluted with 20mL of a methanol/acetonitrile mixture (V/V=2:3), followed by pre-concentration using nitrogen evaporation and analysis with high performance liquid chromatography-ultraviolet spectroscopy (HPLC-UV). Sample extraction was carried out using a Waters Sep-Pak AC-2 Cartridge (with activated carbon). Separation was achieved on a ZIC(®)-Hydrophilic Interaction Liquid Chromatography (ZIC-HILIC) (50mm×2.1mm, 3.5μm) chromatography column and quantification was accomplished based on UV absorbance. A reliable linear relationship was obtained for the calibration curve using standard solutions (R(2)>0.999). Recoveries for dicyandiamide ranged from 84.6% to 96.8%, and the relative standard deviations (RSDs, n=3) were below 6.1% with a detection limit of 5.0ng/mL for stream water samples.

  1. Silica, hybrid silica, hydride silica and non-silica stationary phases for liquid chromatography.

    PubMed

    Borges, Endler M

    2015-04-01

    Free silanols on the surface of silica are the "villains", which are responsible for detrimental interactions of those compounds and the stationary phase (i.e., bad peak shape, low efficiency) as well as low thermal and chemical stability. For these reasons, we began this review describing new silica and hybrid silica stationary phases, which have reduced and/or shielded silanols. At present, in liquid chromatography for the majority of analyses, reversed-phase liquid chromatography is the separation mode of choice. However, the needs for increased selectivity and increased retention of hydrophilic bases have substantially increased the interest in hydrophilic interaction chromatography (HILIC). Therefore, stationary phases and this mode of separation are discussed. Then, non-silica stationary phases (i.e., zirconium oxide, titanium oxide, alumina and porous graphitized carbon), which afford increased thermal and chemical stability and also selectivity different from those obtained with silica and hybrid silica, are discussed. In addition, the use of these materials in HILIC is also reviewed.

  2. Identification of novel circulating coffee metabolites in human plasma by liquid chromatography-mass spectrometry.

    PubMed

    Redeuil, Karine; Smarrito-Menozzi, Candice; Guy, Philippe; Rezzi, Serge; Dionisi, Fabiola; Williamson, Gary; Nagy, Kornél; Renouf, Mathieu

    2011-07-22

    This study reports a liquid chromatography-mass spectrometry method for the detection of polyphenol-derived metabolites in human plasma without enzymatic treatment after coffee consumption. Separation of available standards was achieved by reversed-phase ultra performance liquid chromatography and detection was performed by high resolution mass spectrometry in negative electrospray ionization mode. This analytical method was then applied for the identification and relative quantification of circulating coffee metabolites. A total of 34 coffee metabolites (mainly reduced, sulfated and methylated forms of caffeic acid, coumaric acid, caffeoylquinic acid and caffeoylquinic acid lactone) were identified based on mass accuracy (<4 ppm for most metabolites), specific fragmentation pattern and co-chromatography (when standard available). Among them, 19 circulating coffee metabolites were identified for the first time in human plasma such as feruloylquinic acid lactone, sulfated and glucuronidated forms of feruloylquinic acid lactone and sulfated forms of coumaric acid. Phenolic acid derivatives such as dihydroferulic acid, dihydroferulic acid 4'-O-sulfate, caffeic acid 3'-O-sulfate, dimethoxycinnamic acid, dihydrocaffeic acid and coumaric acid O-sulfate appeared to be the main metabolites circulating in human plasma after coffee consumption. The described method is a sensitive and reliable approach for the identification of coffee metabolites in biological fluids. In future, this analytical method will give more confidence in compound identification to provide a more comprehensive assessment of coffee polyphenol bioavailability studies in humans.

  3. Development and comparison of two dispersive liquid-liquid microextraction techniques coupled to high performance liquid chromatography for the rapid analysis of bisphenol A in edible oils.

    PubMed

    Liu, Shuhui; Xie, Qilong; Chen, Jie; Sun, Janzhi; He, Hui; Zhang, Xiaoke

    2013-06-21

    In this study, two novel sample extraction methods for the analysis of bisphenol A (BPA) in edible oils were developed by using liquid-liquid extraction followed by a dispersive liquid-liquid microextraction (LLE-DLLME) and reversed-phase dispersive liquid-liquid microextraction (RP-DLLME). RP-DLLME showed a superior characteristic over LLE-DLLME and other previously reported procedures because of its easy operation, short extraction time, high sensitivity, low organic solvent consumption and waste generation. The optimized extraction conditions of RP-DLLME for 1.0 g of edible oil diluted in 4 mL of n-hexane were: extractant, 100 μL 0.2 M sodium hydroxide solution (80% methanol, v/v); extraction time, 1 min; centrifugation, 3 min. The determination of BPA was carried out by high performance liquid chromatography coupled with a DAD detector. The method offered excellent linearity over a range of 0.010-0.5 μg g(-1) with a correlation coefficient of r>0.997. Intra-day and inter-day repeatability values expressed as relative standard deviation were 1.9% and 5.9%, respectively. The quantitation limit and detection limit were 6.3 and 2.5 ng g(-1). The target analyte was detected in 5 out of 16 edible oil samples. The recovery rates in real samples ranged from 89.5 to 99.7%.

  4. Isolation and identification of the metolachlor stereoisomers using high-performance liquid chromatography, polarimetric measurements, and enantioselective gas chromatography.

    PubMed

    Müller, M D; Poiger, T; Buser, H

    2001-01-01

    Because of the presence of two chiral elements (an asymmetrically substituted carbon and a chiral axis), the herbicide metolachlor consists of four stereoisomers stable at ambient temperature with aSS-, aRS-, aSR-, and aRR-configurations (aSS, the isomer with aS,1'S-configuration, etc.). Metolachlor, initially introduced into the market as the racemic product containing all four stereoisomers, is currently being replaced worldwide by S-metolachlor, the product enantiomerically enriched with the herbicidally active 1'S-isomers (aSS, aRS). The isomer-specific analysis of metolachlor requires not only enantioselective ("chiral") analytical techniques but also suitable reference compounds. In this study, two of the four metolachlor isomers were isolated from rac-metolachlor in enantio- (ee > 98%) and diastereomerically pure forms by a combination of achiral and chiral high-performance liquid chromatography (HPLC). The two isomers were identified as the aSS- and the aRR-isomers by polarimetric measurements, in reference to previous data. The two isomers were then thermally equilibrated to 1:1 mixtures of the aSS/aRS and aRR/aSR diastereomers, respectively, so that analytical data of all four metolachlor isomers became available; they were then used to identify these isomers in technical products by chiral high-resolution gas chromatography (HRGC). The kinetics of the thermally induced interconversion of the atropisomers was studied and the consequences, such as for GC analysis, are discussed. A comparison of on-column and split/splitless injection indicated that the latter technique results in significant isomerization prior to separation and, therefore, cannot be used for accurate isomer analysis.

  5. Hydrophilic interaction chromatography versus reversed phase liquid chromatography coupled to mass spectrometry: effect of electrospray ionization source geometry on sensitivity.

    PubMed

    Periat, Aurélie; Kohler, Isabelle; Bugey, Aurélie; Bieri, Stefan; Versace, François; Staub, Christian; Guillarme, Davy

    2014-08-22

    In this study, the influence of electrospray ionization (ESI) source design on the overall sensitivity achieved in hydrophilic interaction chromatography (HILIC) and reversed phase liquid chromatography (RPLC), was investigated. State-of-the-art triple quadrupole mass analyzers from AB Sciex, Agilent Technologies and Waters equipped with brand specific source geometries were tested with various mobile phase pH on 53 pharmaceutical compounds. The design of the ESI source showed to strongly influence the gain in sensitivity that can be achieved in HILIC compared to RPLC mode. The 6460 Triple Quadrupole LC/MS system from Agilent Technologies was particularly affected by mobile phase settings. Indeed, compared to RPLC conditions, 92% of the compounds had an increased signal-to-noise ratio at a flow rate of 300 μL/min in HILIC mode at pH 6, while this percentage dropped to only 7% at 1000 μL/min and pH 3. In contrast, the influence of flow rate and mobile phase pH on the gain in sensitivity between RPLC and HILIC was found very limited with the API 5000 LC/MS/MS system from AB Sciex, as only 15 to 36% of the tested compounds showed an enhanced sensitivity in HILIC mode. With the Xevo TQ-S instrument from Waters, superior sensitivity in HILIC was noticed for 85% of the compounds with optimal conditions (i.e., pH 3 and 1000 μL/min), whereas at sub-optimal conditions (i.e. pH 6 and 300 μL/min), it represented less than 50%. The gain in sensitivity observed in HILIC was found less significant with the recent LC-MS platforms used in this study than for old-generation instruments. Indeed, the improved ESI sources equipping the recent mass analyzers allow for enhanced evaporation efficiency, mainly for RPLC mobile phases containing high proportion of water and this even at high flow rates.

  6. Preparative Isolation and Purification of Flavone C-Glycosides from the Leaves of Ficus microcarpa L. f by Medium-Pressure Liquid Chromatography, High-Speed Countercurrent Chromatography, and Preparative Liquid Chromatography.

    PubMed

    Wang, Xiaohong; Liang, Yong; Zhu, Licai; Xie, Huichun; Li, Hang; He, Junting; Pan, Man; Zhang, Tianyou; Ito, Yoichiro

    2010-01-01

    Combined with medium-pressure liquid chromatography (MPLC) and preparative high-performance liquid chromatography (perp-HPLC), high-speed countercurrent chromatography (HSCCC) was applied for separation and purification of flavone C-glycosides from the crude extract of leaves of Ficus microcarpae L. f. HSCCC separation was performed on a two-phase solvent system composed of methyl tert- butyl ether - ethyl acetate - 1-butanol - acetonitrile - 0.1% aqueous trifluoroacetic acid at a volume ratio of 1:3:1:1:5. Partially resolved peak fractions from HSCCC separation were further purified by preparative HPLC. Four well-separated compounds were obtained and their purities were determined by HPLC. The purities of these peaks were 97.28%, 97.20%, 92.23%, and 98.40%.. These peaks were characterized by ESI-MS(n). According to the reference, they were identified as orientin (peak I), isovitexin-3″-O-glucopyranoside (peak II), isovitexin (peak III), and vitexin (peak IV), yielded 1.2 mg, 4.5 mg, 3.3 mg, and 1.8 mg, respectively.

  7. Performance and limits of liquid chromatography isotope ratio mass spectrometry system for halogenated compounds

    NASA Astrophysics Data System (ADS)

    Gilevska, Tetyana; Gehre, Matthias; Richnow, Hans

    2014-05-01

    Compound Specific Isotope Analysis (CSIA) has been an important step for the assessment of the origin and fate of compounds in environmental science.[1] Biologically or pharmaceutically important compounds often are not amenable for gas chromatographic separation because of high polarity and lacking volatility, thermostability. In 2004 liquid chromatography isotope ratio mass spectrometry (LC-IRMS) became commercially available. LC-IRMS system intent a quantitative conversion of analytes separation into CO2 via wet oxidation with sodium persulfate in the presence of phosphoric acid while analytes are still dissolved in the aqueous liquid phase.[2] The aim of this study is to analyze the oxidation capacity of the interface of the LC-IRMS system and determine which parameters could improve oxidation of compounds which are resistant to persulfate oxidation. Oxidation capacity of the liquid chromatography isotope ratio mass spectrometry system was tested with halogenated acetic acid and a set of aromatic compounds with different substitutes. Acetic acid (AA) was taken as a model compound for complete oxidation and compared to the oxidation of other analytes on a molar basis. Correct values were obtained for di- and mono chlorinated and fluorinated and also for tribrominated acetic acid and for all studied aromatic compounds. Incomplete oxidation for trichloroacetic (TCAA) and trifluoroacetic (TFAA) acid was revealed with lower recovery compared to acetic acid and isotope fractionation leading to depleted carbon isotope composition compared to values obtained with an elementary analyzer connected to an isotope mass spectrometer Several optimization steps were tried in order to improve the oxidation of TCAA and TFAA: (i) increasing the concentration of the oxidizing agent, (ii) variation of flow rate of the oxidizing and acid solution, (iii) variation of flow rate of liquid chromatography pump (iv) addition of a catalyzer. These modifications lead to longer reaction time

  8. Therapeutic drug monitoring for sirolimus in whole blood of organ transplants by high-performance liquid chromatography with ultraviolet detection.

    PubMed

    Campanero, Miguel Angel; Cardenas, Ernesto; Sádaba, Belén; García-Quetglas, Emilio; Muñoz-Juarez, Maria Jose; Gil-Aldea, Isabel; Pazo, David; Azanza, Jose Ramón; Honorato, Jesús

    2004-03-26

    We developed and validated an accurate, sensitive, precise and rapid HPLC method with UV detection for the determination of sirolimus in blood samples from renal, cardiac and hepatic transplants. This method overcomes most of the problems related to previously published assays using a narrow-bore column with base deactivated C18 reversed phase. Whole blood samples were purified by a combination of a precipitating blood matrix with zinc sulphate and a single step liquid-liquid extraction with acetone and 1-chlorobutane. Calibration curves (range 2.5-150 ng/ml), were linear with coefficients of correlation better than 0.996. The relative standard deviation was determined to be less than 8%. The present method has also been validated by a reference laboratory (St. George's Hospital Medical School, London, UK). More of 300 clinical samples have been analysed with this method.

  9. Determination of sucrose in equine serum using liquid chromatography-mass spectrometry (LC/MS).

    PubMed

    D'Arcy-Moskwa, E; Weston, L; Noble, G N; Raidal, S L

    2011-11-15

    Mucosal integrity may be objectively assessed by determination of the absorption of exogenous substances such as sucrose. Gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-mass spectrometry (LC/MS) have been reported for the accurate quantification of low concentrations of sucrose in serum. LC/MS offered the advantage of high sensitivity and mass selectivity without the need for extensive sample derivatization required for GC/MS methods. However, the high polarity and non-volatile nature of the sucrose molecule renders LC/MS techniques challenging. Previously published reports lacked sufficient detail to permit replication of methodology. Problems encountered with existing protocols included poor peak resolution and weak fragmentation of the parent molecule. This communication describes a LC/MS protocol developed to provide improved resolution and product detection.

  10. Glycosaminoglycans: oligosaccharide analysis by liquid chromatography, capillary electrophoresis, and specific labeling.

    PubMed

    Langeslay, Derek J; Jones, Christopher J; Beni, Szabolcs; Larive, Cynthia K

    2012-01-01

    Glycosaminoglycans (GAGs) are a class of biopolymers that include chondrotin sulfate, dermatan sulfate, keratan sulfate, hyaluronic acid, heparin, and heparan sulfate. The GAGs are linear polysaccharides that are microheterogeneous in composition and polydisperse in size. Because they have the most complex structures, this article is aimed at describing a step-by-step procedure for processing and analyzing heparin and heparan sulfate-derived oligosaccharides, although the basic protocols and procedures apply equally well to other members of the GAG family. The methods described in this manuscript include the preparation of oligosaccharides through enzymatic depolymerization, size fractionation by preparative scale size-exclusion chromatography (SEC), and disaccharide isomer analysis by reverse-phase ion-pair high-performance liquid chromatography (RPIP-HPLC) and capillary electrophoresis (CE).

  11. Detection of thiazide-based diuretics in equine urine by liquid chromatography/mass spectrometry.

    PubMed

    Garbís, S D; Hanley, L; Kalita, S

    1998-01-01

    Thiazide-based diuretics are included in the list of banned drugs in the horse-racing industry. One effect of their misuse is increased urine flow, contributing to dilution of other doping agents. Their determination is essential in ensuring compliance to horse-racing regulation. This study evaluates the feasibility of using liquid chromatography/mass spectrometry (LC/MS) with electrospray and atmospheric pressure chemical ionization interfaces to analyze thiazidic diuretics in equine urine samples. Existing LC and gas chromatography/MS methods are limited in their applicability to thiazide analysis. Sample preparation, analyte extraction, chromatographic separation, ion-source collision induced dissociation, solvent composition, ionization mode, and ion polarity are discussed. The practicality of LC/MS for this analysis is demonstrated with actual equine administration samples collected at specified time intervals. Detection limits were 270 ng/mL for chlorothiazide, 131 ng/mL for hydrochlorothiazide, and 384 ng/mL for trichlormethiazide.

  12. Study of the separation limits of continuous solid support free liquid-liquid chromatography: separation of capsaicin and dihydrocapsaicin by centrifugal partition chromatography.

    PubMed

    Goll, Johannes; Frey, Andreas; Minceva, Mirjana

    2013-04-05

    Sequential centrifugal partition chromatography (sCPC) is a cyclic solid support-free liquid-liquid chromatographic process, in which a continuously introduced feed mixture is separated into two sequentially collected product streams. The few experimental demonstrations of this concept already revealed its potential for the preparative separation of pharmaceuticals and fine chemicals. In this work not only the possibilities, but also the limits of the sCPC technology are explored. A feed mixture consisting of capsaicin and dihydrocapsaicin, whose molecular structure differs in only one double bond, was selected for this purpose. The sCPC unit operating parameters needed for a complete separation of the feed mixture were selected using the recently published approach, which uses the partition coefficient of the feed components and the hydrodynamic characteristics of the system as input data. A complete separation of capsaicin and dihydrocapsaicin with the solvent system heptane/ethyl acetate/methanol/water:1/1/1/1 (v/v/v/v) was achieved, although the separation factor was only 1.32. The sCPC unit separation performance was successfully simulated using the cell model.

  13. Determination of alternative preservatives in cosmetic products by chromophoric derivatization followed by vortex-assisted liquid-liquid semimicroextraction and liquid chromatography.

    PubMed

    Miralles, Pablo; Vrouvaki, Ilianna; Chisvert, Alberto; Salvador, Amparo

    2016-07-01

    An analytical method for the simultaneous determination of phenethyl alcohol, methylpropanediol, phenylpropanol, caprylyl glycol, and ethylhexylglycerin, which are used as alternative preservatives in cosmetic products, has been developed. The method is based on liquid chromatography with UV spectrophotometric detection after chromophoric derivatization with benzoyl chloride and vortex-assisted liquid-liquid semimicroextraction. Different chromatographic parameters, derivatization conditions, and sample preparation variables were studied. Under optimized conditions, the limits of detection values for the analytes ranged from 0.02 to 0.06µgmL(-1). The method was validated with good recovery values (84-118%) and precision values (3.9-9.5%). It was successfully applied to 10 commercially available cosmetic samples. The good analytical features of the proposed method besides of its environmentally-friendly characteristics, make it useful to carry out the quality control of cosmetic products containing the target compounds as preservative agents.

  14. Low Density Solvent-Based Dispersive Liquid-Liquid Microextraction for the Determination of Synthetic Antioxidants in Beverages by High-Performance Liquid Chromatography

    PubMed Central

    Çabuk, Hasan; Köktürk, Mustafa

    2013-01-01

    A simple and efficient method was established for the determination of synthetic antioxidants in beverages by using dispersive liquid-liquid microextraction combined with high-performance liquid chromatography with ultraviolet detection. Butylated hydroxy toluene, butylated hydroxy anisole, and tert-butylhydroquinone were the antioxidants evaluated. Experimental parameters including extraction solvent, dispersive solvent, pH of sample solution, salt concentration, and extraction time were optimized. Under optimal conditions, the extraction recoveries ranged from 53 to 96%. Good linearity was observed by the square of correlation coefficients ranging from 0.9975 to 0.9997. The relative standard deviations ranged from 1.0 to 5.2% for all of the analytes. Limits of detection ranged from 0.85 to 2.73 ng mL−1. The method was successfully applied for determination of synthetic antioxidants in undiluted beverage samples with satisfactory recoveries. PMID:23853535

  15. Determination of spirocyclic tetronic/tetramic acid derivatives and neonicotinoid insecticides in fruits and vegetables by liquid chromatography and mass spectrometry after dispersive liquid-liquid microextraction.

    PubMed

    Pastor-Belda, Marta; Garrido, Isabel; Campillo, Natalia; Viñas, Pilar; Hellín, Pilar; Flores, Pilar; Fenoll, José

    2016-07-01

    Dispersive liquid-liquid microextraction was used to preconcentrate three spirocyclic tetronic/tetramic acid derivatives (spirotetramat, spiromesifen and spirodiclofen) and five neonicotinoid (thiamethoxam, chlotianidin, imidacloprid, acetamiprid and thiacloprid) insecticides previously extracted from fruit and vegetable matrices with acetonitrile. The organic enriched phase was evaporated, reconstituted in 25μL acetonitrile and analyzed by reversed-phase liquid chromatography with tandem mass spectrometry using a triple quadrupole in selected reaction monitoring mode. Enrichment factors in the 15-100 range were obtained. A matrix effect was observed, the detection limits varying between 0.025 and 0.5ngg(-1), depending on the compound and the sample matrix. The developed method was applied to the analysis of 25 samples corresponding to five different fruit and vegetable matrices. Only thiamethoxam was detected in a lemon sample at a concentration close to the quantification limit, and spiromesifen and spirotetramat at concentrations between 11.6 and 54.5ngg(-1).

  16. Analysis of estrogens and androgens in postmenopausal serum and plasma by liquid chromatography-mass spectrometry.

    PubMed

    Wang, Qingqing; Bottalico, Lisa; Mesaros, Clementina; Blair, Ian A

    2015-07-01

    Liquid chromatography-selected reaction monitoring/mass spectrometry-based methodology has evolved to the point where accurate analyses of trace levels of estrogens and androgens in postmenopausal serum and plasma can be accomplished with high precision and accuracy. A suite of derivatization procedures has been developed, which together with modern mass spectrometry instrumentation provide investigators with robust and sensitive methodology. Pre-ionized derivatives are proving to be useful as they are not subject to suppression of the electrospray signal. Postmenopausal women with elevated plasma or serum estrogens are thought to be at increased risk for breast and endometrial cancer. Therefore, significant advances in risk assessment should be possible now that reliable methodology is available. It is also possible to conduct analyses of multiple estrogens in plasma or serum. Laboratories that are currently employing liquid chromatography/mass spectrometry methodology can now readily implement this strategy. This will help conserve important plasma and serum samples available in Biobanks, as it will be possible to conduct high sensitivity analyses using low initial sample volumes. Reported levels of both conjugated and non-conjugated estrogen metabolites are close to the limits of sensitivity of many assays to date, urging caution in the interpretation of these low values. The analysis of serum androgen precursors in postmenopausal women has not been conducted routinely in the past using liquid chromatography/mass spectrometry methodology. Integration of serum androgen levels into the panel of metabolites analyzed could provide additional information for assessing cancer risk and should be included in the future.

  17. Detecting trace components in liquid chromatography/mass spectrometry data sets with two-dimensional wavelets

    NASA Astrophysics Data System (ADS)

    Compton, Duane C.; Snapp, Robert R.

    2007-09-01

    TWiGS (two-dimensional wavelet transform with generalized cross validation and soft thresholding) is a novel algorithm for denoising liquid chromatography-mass spectrometry (LC-MS) data for use in "shot-gun" proteomics. Proteomics, the study of all proteins in an organism, is an emerging field that has already proven successful for drug and disease discovery in humans. There are a number of constraints that limit the effectiveness of liquid chromatography-mass spectrometry (LC-MS) for shot-gun proteomics, where the chemical signals are typically weak, and data sets are computationally large. Most algorithms suffer greatly from a researcher driven bias, making the results irreproducible and unusable by other laboratories. We thus introduce a new algorithm, TWiGS, that removes electrical (additive white) and chemical noise from LC-MS data sets. TWiGS is developed to be a true two-dimensional algorithm, which operates in the time-frequency domain, and minimizes the amount of researcher bias. It is based on the traditional discrete wavelet transform (DWT), which allows for fast and reproducible analysis. The separable two-dimensional DWT decomposition is paired with generalized cross validation and soft thresholding. The Haar, Coiflet-6, Daubechie-4 and the number of decomposition levels are determined based on observed experimental results. Using a synthetic LC-MS data model, TWiGS accurately retains key characteristics of the peaks in both the time and m/z domain, and can detect peaks from noise of the same intensity. TWiGS is applied to angiotensin I and II samples run on a LC-ESI-TOF-MS (liquid-chromatography-electrospray-ionization) to demonstrate its utility for the detection of low-lying peaks obscured by noise.

  18. Predicting the behaviour of polydisperse polymers in liquid chromatography under isocratic and gradient conditions.

    PubMed

    Schoenmakers, Peter; Fitzpatrick, Fiona; Grothey, Ricarda

    2002-08-02

    In this paper we describe how the existing theories to describe retention and peak width in isocratic and gradient-elution liquid chromatography can be expanded to describe the retention behaviour of natural and synthetic repetitive polymers, which feature distributions of molecules with different masses (and often different structures) rather than unambiguous molecular formulas. For polydisperse samples, it is vital that the model accommodates (isocratic) elution of sample components before the onset of a gradient, elution during the gradient, and elution after the completion of the gradient. The expanded models can readily be implemented in standard spreadsheet software, such as Excel. We have created such spreadsheets based on the conventional model for retention in reversed-phase liquid chromatography (RPLC) and on two different models for retention in normal-phase liquid chromatography. The implementation allows an easy visualization of the theoretical concept. Up to three different polymeric series can be entered, with a total of up to 100 peaks being computed and displayed in isocratic or gradient-elution chromatograms. Also visualized are "retention models" (diagrams of isocratic retention vs. composition) and "calibration curves" (retention or elution composition vs. molecular mass or degree of polymerization). The coefficients in the isocratic retention model may be correlated, as has often been observed in RPLC. It is shown that under certain conditions such a correlation corresponds to the existence of so-called critical (isocratic) conditions, at which all the members of a given polymeric series (same composition and end groups, different number of repeat units) show co-elution.

  19. Integration of electrochemistry with ultra-performance liquid chromatography/mass spectrometry.

    PubMed

    Cai, Yi; Zheng, Qiuling; Liu, Yong; Helmy, Roy; Loo, Joseph A; Chen, Hao

    2015-01-01

    This study presents the development of ultra-performance liquid chromatography (UPLC) mass spectrometry (MS) combined with electrochemistry (EC) for the first time and its application for the structural analysis of proteins/peptides that contain disulfide bonds. In our approach, a protein/peptide mixture sample undergoes a fast UPLC separation and subsequent electrochemical reduction in an electrochemical flow cell followed by online MS and tandem mass spectrometry (MS/MS) analyses. The electrochemical cell is coupled to the mass spectrometer using our recently developed desorption electrospray ionization (DESI) interface. Using this UPLC/EC/DESI-MS method, peptides that contain disulfide bonds can be differentiated from those without disulfide bonds, as the former are electroactive and reducible. MS/MS analysis of the disulfide-reduced peptide ions provides increased information on the sequence and disulfide-linkage pattern. In a reactive DESI- MS detection experiment in which a supercharging reagent was used to dope the DESI spray solvent, increased charging was obtained for the UPLC-separated proteins. Strikingly, upon online electrolytic reduction, supercharged proteins (e.g., α-lactalbumin) showed even higher charging, which will be useful in top- down protein structure MS analysis as increased charges are known to promote protein ion dissociation. Also, the separation speed and sensitivity are enhanced by approximately 1(~)2 orders of magnitude by using UPLC for the liquid chromatography (LC)/EC/MS platform, in comparison to the previously used high- performance liquid chromatography (HPLC). This UPLC/EC/DESI-MS method combines the power of fast UPLC separation, fast electrochemical conversion, and online MS structural analysis for a potentially valuable tool for proteomics research and bioanalysis.

  20. Characterization of rhamnolipids by liquid chromatography/mass spectrometry after solid-phase extraction.

    PubMed

    Behrens, Beate; Engelen, Jeannine; Tiso, Till; Blank, Lars Mathias; Hayen, Heiko

    2016-04-01

    Rhamnolipids are surface-active agents with a broad application potential that are produced in complex mixtures by bacteria of the genus Pseudomonas. Analysis from fermentation broth is often characterized by laborious sample preparation and requires hyphenated analytical techniques like liquid chromatography coupled to mass spectrometry (LC-MS) to obtain detailed information about sample composition. In this study, an analytical procedure based on chromatographic method development and characterization of rhamnolipid sample material by LC-MS as well as a comparison of two sample preparation methods, i.e., liquid-liquid extraction and solid-phase extraction, is presented. Efficient separation was achieved under reversed-phase conditions using a mixed propylphenyl and octadecylsilyl-modified silica gel stationary phase. LC-MS/MS analysis of a supernatant from Pseudomonas putida strain KT2440 pVLT33_rhlABC grown on glucose as sole carbon source and purified by solid-phase extraction revealed a total of 20 congeners of di-rhamnolipids, mono-rhamnolipids, and their biosynthetic precursors 3-(3-hydroxyalkanoyloxy)alkanoic acids (HAAs) with different carbon chain lengths from C8 to C14, including three rhamnolipids with uncommon C9 and C11 fatty acid residues. LC-MS and the orcinol assay were used to evaluate the developed solid-phase extraction method in comparison with the established liquid-liquid extraction. Solid-phase extraction exhibited higher yields and reproducibility as well as lower experimental effort.

  1. Determination of three estrogens and bisphenol A by functional ionic liquid dispersive liquid-phase microextraction coupled with ultra-high performance liquid chromatography and ultraviolet detection.

    PubMed

    Jiang, Yuehuang; Tang, Tingting; Cao, Zhen; Shi, Guoyue; Zhou, Tianshu

    2015-06-01

    A hydroxyl-functionalized ionic liquid, 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, was employed in an improved dispersive liquid-phase microextraction method coupled with ultra high performance liquid chromatography for the enrichment and determination of three estrogens and bisphenol A in environmental water samples. The introduced hydroxyl group acted as the H-bond acceptor that dispersed the ionic liquid effectively in the aqueous phase without dispersive solvent or external force. Fourier transform infrared spectroscopy indicated that the hydroxyl group of the cation of the ionic liquid enhanced the combination of extractant and analytes through the formation of hydrogen bonds. The improvement of the extraction efficiency compared with that with the use of alkyl ionic liquid was proved by a comparison study. The main parameters including volume of extractant, temperature, pH, and extraction time were investigated. The calibration curves were linear in the range of 5.0-1000 μg/L for estrone, estradiol, and bisphenol A, and 10.0-1000 μg/L for estriol. The detection limits were in the range of 1.7-3.4 μg/L. The extraction efficiency was evaluated by enrichment factor that were between 85 and 129. The proposed method was proved to be simple, low cost, and environmentally friendly for the determination of the four endocrine disruptors in environmental water samples.

  2. Quantification of PSP toxins in toxic shellfish matrices using post-column oxidation liquid chromatography and pre-column oxidation liquid chromatography methods suggests post-column oxidation liquid chromatography as a good monitoring method of choice.

    PubMed

    Rey, Verónica; Botana, Ana M; Botana, Luis M

    2017-04-01

    Different shellfish samples were analyzed by Pre- and Post-Column Oxidation Liquid Chromatography to compare the toxins profiles and get information about the degree of accomplishment of both methods. Comparison of the results obtained, the linear correlation coefficient (r(2) = 0.94) and the paired t test (two tails, α = 0.05), indicated that there were not significant differences between both sets of data. Nevertheless, important differences related to toxins profiles were found: it was remarkable the difference in results for both Gonyautoxins 1 and 4 and Decarbamoylgonyautoxins 2 and 3, depending on the method of choice, due to an overestimation in the Pre-Column method. It was necessary to modify the elution conditions in the Post-Column method to avoid the interference of matrix peaks at retention times closer to the retention times of the calibrants, mostly when working with oyster and scallop matrices, although it is a good method to use routinely.

  3. Microwave-immobilized polybutadiene stationary phase for reversed-phase high-performance liquid chromatography.

    PubMed

    Lopes, Nilva P; Collins, Kenneth E; Jardim, Isabel C S F

    2004-03-19

    Polybutadiene (PBD) has been immobilized on high-performance liquid chromatography (HPLC) silica by microwave radiation at various power levels (52-663 W) and actuation times (3-60 min). Columns prepared from these reversed-phase HPLC materials, as well as from similar non-irradiated materials, were tested with standard sample mixtures and characterized by elemental analysis (%C) and infrared spectroscopy. A microwave irradiation of 20 min at 663 W gives a layer of immobilized PBD that presented good performance. Longer irradiation times give thicker immobilized layers having less favorable chromatographic properties.

  4. [Determination of scopoletin and umbelliferone contents in Saussurea medusa Maxim by high-performance liquid chromatography].

    PubMed

    Su, Wei-wei; Zhao, Jie; Lin, Jing-ming

    2005-01-01

    The contents of scopoletin and umbelliferone in Saussurea medusa Maxim were determined by high-performance liquid chromatography (HPLC) using Merck Lichrospher100 RP-18e column (250 mm x 4.0 mm, 5 microm) with the mobile phase of methanol-tetrahydrofuran-water solution and the absorbance of the compounds observed at 346 nm. HPLC yielded an average recovery and RSD of 100.07% and 1.42% for scopoletin, and 99.41% and 2.06% for umbelliferone, respectively, suggesting that HPLC is a simple, rapid and accurate method for quality control of Saussurea medusa Maxim.

  5. Anomalous properties of flavonoids in reversed phase high performance liquid chromatography

    NASA Astrophysics Data System (ADS)

    Zenkevich, I. G.; Gushchina, S. V.

    2011-09-01

    It is shown through reversed phase high performance liquid chromatography that a characteristic feature of such abundant natural flavonoids as flavon-3-ols is an anomalously strong antibate dependence of their retention indices ( RI) on the organic solvent concentration ( C) in the eluent, dRI/ dC < 0. In order to interpret this anomaly, the specific optical rotation values [α]{D/20} of natural (+)-(2 R,3 R)-dihydroquercetin in different solvents are compared, confirming the reverse formation of hydrated flavonoids in aqueous solutions.

  6. Two-dimensional liquid chromatography study of the human whole saliva proteome.

    PubMed

    Wilmarth, Phillip A; Riviere, Michael A; Rustvold, D Leif; Lauten, Jeffrey D; Madden, Theresa E; David, Larry L

    2004-01-01

    The human whole saliva proteome was investigated using two-dimensional liquid chromatography (2-DLC). The 2-DLC study was able to identify, with high confidence, 102 proteins including most known salivary proteins (35), and a large number of common serum proteins (67). Peptides from proline-rich proteins, abundant in saliva, had unusual cleavage sites and were frequently only partially tryptic. Three proteins not previously observed in human saliva were also detected. Significantly greater numbers of identified proteins, including high molecular weight, low molecular weight, and proline-rich proteins, were found with 2-DLC compared to previously reported two-dimensional gel electrophoresis studies.

  7. [Analysis of psychotropic drug mixtures using high-pressure liquid chromatography in acute poisoning cases].

    PubMed

    Kazlauskiene, Daiva; Vainauskas, Paulius; Kazlauskas, Saulius

    2002-01-01

    The qualitative and quantitative method of determination of amitryptilin, codeine and fluoxetine in the mixture using high-pressure liquid chromatography is described in this paper. Chromatogram is presented which shows, that preparations are fully separated and do not interfere each others analysis. Tables with chromatographical separation characteristics are also presented. Proposed calibration curves of quantitative analysis and calculated medium relative error of quantitative ascertainment for every preparation of the mixture are shown. Final conclusion: method is applicable for qualitative and quantitative analysis of amitryptiline, fluoxetine and codeine in the mixture in hasty poisoning cases.

  8. Characterization of honey amino acid profiles using high-pressure liquid chromatography to control authenticity.

    PubMed

    Cotte, J F; Casabianca, H; Giroud, B; Albert, M; Lheritier, J; Grenier-Loustalot, M F

    2004-03-01

    Amino acid analysis of honey by high-performance liquid chromatography (HPLC) was used first to discriminate different botanical origins and then to combat adulteration. Pure honeys of seven selected floral varieties were examined. A principal component analysis (PCA) was carried out on the results after selection of the most discriminating parameters. Lavender honeys were thus perfectly characterized, but complete satisfaction was not obtained with the six other varieties. This method (analysis by HPLC and statistical processing by PCA) enabled us to detect the addition of sugar syrup to rape and fir honeys.

  9. Determination of rhoifolin and daidzin in human plasma by high-performance liquid chromatography.

    PubMed

    Ishii, K; Urano, S; Furuta, T; Kasuya, Y

    1994-05-13

    A method for determining flavonoids in human plasma is presented for application to pharmacokinetic studies of two flavonoids, rhoifolin and daidzin. Isocratic reversed-phase high-performance liquid chromatography (HPLC) was used with genistin as an internal standard and solid-phase extraction using a Sep-Pak C18 cartridge. The mobile phases were acetonitrile-0.1 M ammonium acetate solution (20:80, v/v) for rhoifolin and methanol-0.1 M ammonium acetate solution (33:67, v/v) for daidzin. The detection limits on-column were 2 ng for rhoifolin and 0.5 ng for daidzin.

  10. Mapping Protein Abundance Patterns in the Brain Using Voxelation Combined with Liquid Chromatography and Mass Spectrometry

    PubMed Central

    Petyuk, Vladislav A.; Qian, Wei-Jun; Smith, Richard D.; Smith, Desmond J.

    2009-01-01

    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. PMID:19654045

  11. Determination of amphetamine and methamphetamine in umbilical cord using liquid chromatography-tandem mass spectrometry.

    PubMed

    Jones, Joseph; Rios, Rosemarie; Jones, Mary; Lewis, Douglas; Plate, Charles

    2009-11-01

    The use of meconium as a drug-screening matrix for newborns has been the gold standard of care for the past two decades. A recent study using matched pairs of meconium and umbilical cord demonstrated a high degree of agreement. The use of liquid chromatography-tandem mass spectrometry as a means to confirm amphetamines presumptive positive umbilical cord specimens for amphetamine and methamphetamine is described here for the first time. The limit of detection for both compounds was 0.2 ng/g. The limit of quantitation for both compounds was 0.6 ng/g. The assay was linear for both compounds up to 100 ng/g.

  12. Study of Saiga Horn Using High-Performance Liquid Chromatography with Mass Spectrometry

    PubMed Central

    Mikulíková, Kateřina; Romanov, Oleg; Miksik, Ivan; Eckhardt, Adam; Pataridis, Statis; Sedláková, Pavla

    2012-01-01

    The saiga horns have been investigated the using of modern analytic methods. High-performance liquid chromatography (HPLC) with mass-spectrometric (MS and MS/MS) detection and polyacrylamide gel electrophoresis (PAGE) were used. It could be concluded that basic proteins of the saiga horns are keratins and collagen. The basic representation protein in all samples is keratin type I microfibrillar (from sheep), keratin type II microfibrillar (from sheep), collagen type I (α1) (from bovine) and collagen type I (α2) (from bovine). Free amino acids we determined in all samples are nontreated by enzyme. PMID:22629195

  13. ION-pair liquid chromatography technique for the estimation of metformin in its multicomponent dosage forms.

    PubMed

    Vasudevan, M; Ravi, J; Ravisankar, S; Suresh, B

    2001-04-01

    A simple, precise and accurate high performance liquid chromatography (HPLC) method was developed for the simultaneous estimation of metformin with gliclazide and glipizide present in multicomponent dosage forms. The method was carried out on Inertsil C(18) column. A mobile phase composed of acetonitrile-water containing camphor sulphonic acid (adjusted to pH 7 using 0.1 N sodium hydroxide; 75 mM) at a flow rate of 1 ml min(-1) was used for the separation. Detection was carried out at 225 nm. Tolbutamide was used as internal standard. Validation of the developed HPLC method was carried out.

  14. Applications of liquid chromatography-mass spectrometry in metabolic studies of explosives.

    PubMed

    Yinon, J; Hwang, D G

    1987-05-08

    Liquid chromatography-mass spectrometry was used for the detection and identification of metabolites of 2,4,6-trinitrotoluene (TNT) in urine and blood. The metabolites were found in the urine of rats and in the blood of rabbits fed with TNT, in the urine of rats exposed to TNT by skin absorption and in the urine of TNT munition workers. The detected metabolites, formed by reduction processes, included 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, 2,4-diamino-6-nitrotoluene and 2,6-diamino-4-nitrotoluene, in addition to untransformed TNT.

  15. Determination of histamine in tomatoes by liquid chromatography/mass spectrometry.

    PubMed

    Bolygo, E; Cooper, P A; Jessop, K M; Moffatt, F

    2000-01-01

    The histamine level in tomato fruits and pastes was determined by 2 orthogonal techniques as a means of comparing accuracy. Close statistical agreement was found between assays for free histamine by capillary electrophoresis (with UV absorbance detection), and for the dansyl derivative by reversed-phase liquid chromatography (LC). Both techniques have adequate sensitivity for the analysis of endogenous histamine in tomatoes, but LC/electrospray tandem mass spectrometry was more sensitive by at least an order of magnitude, down to a level of 0.05 mg/kg.

  16. Microplates in liquid chromatography--new solution in clinical research? A review.

    PubMed

    Krcmova, Lenka; Solichova, Dagmar; Solich, Petr

    2013-10-15

    Microplates are routinely used in Radio- or Immuno-assays. Recently, microplates have found use not only in analytical but also in the pre-analytical phase in bioanalyses (sample storage, sample preparation). New connection of this technology to liquid chromatography could be economical, fast and simple solution for many routine laboratories handling large sequences of biological samples. This review summarises the application of microplates in bioanalytical laboratories. Different types of sorbents, materials and shapes of microplates are discussed, and the main advantages and disadvantages of microplates used in clinical research are presented.

  17. Separation of polyamines, conjugated to DNA, by reversed-phase high-performance liquid chromatography.

    PubMed

    Mateos, J L; Reyes, A; Vicente, C; Legaz, M E

    2000-02-18

    Genomic DNA was isolated from the lichen Evernia prunastri in order to analyze by high-performance liquid chromatography the occurrence of polyamines conjugated to the macromolecule. The acid-insoluble (PH) fraction of this DNA contained mainly conjugated spermidine, although small amounts of free putrescine and spermidine were also present. The PH fraction of DNA also contained conjugated evernic acid, the main phenol produced by this lichen species. Conjugation of polyamines to calf thymus DNA was carried out under in vitro conditions. Conjugation was to spermidine and mainly to spermine and produced DNA compactation. Evernic acid enhanced the action of polyamines in order to produce DNA aggregation.

  18. Analysis of doxylamine in plasma by high-performance liquid chromatography.

    PubMed

    Kohlhof, K J; Stump, D; Zizzamia, J A

    1983-08-01

    A rapid and sensitive high-performance liquid chromatographic (HPLC) assay for the quantitative determination of doxylamine in plasma is described. The drug levels of doxylamine in plasma were monitored after the oral administration of a single 25-mg tablet of doxylamine succinate to each of 20 male volunteers. The compound was extracted from the plasma samples, concentrated under a nitrogen stream, and analyzed by HPLC using normal-phase chromatography with detection at 254 nm. The detection limit is approximately 5 ng/ml.

  19. An enzymatic method for assaying sulbactam in human serum: comparison with high performance liquid chromatography.

    PubMed

    Sotto, A; Peray, P; Geny, F; Brunschwig, C; Carrière, C; Galtier, M; Ramuz, M; Jourdan, J

    1995-03-01

    An enzymatic method using nitrocefin as substrate was developed to assay sulbactam in human serum. Serum containing sulbactam was incubated with purified titrated TEM-1 beta-lactamase and nitrocefin was then added to the mixture to determine the remaining beta-lactamase activity and consequently the concentration of sulbactam. Assays were carried out on five patients with pulmonary infections receiving sulbactam plus amoxycillin iv. The values for serum sulbactam concentrations determined by the enzymatic method were compared with those determined by high performance liquid chromatography (HPLC). The correlation coefficient was 0.990 for serum sulbactam concentrations below 15 mg/L.

  20. 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

  1. Derivatization reagents in liquid chromatography/electrospray ionization tandem mass spectrometry.

    PubMed

    Santa, Tomofumi

    2011-01-01

    Liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) is one of the most prominent analytical techniques owing to its inherent selectivity and sensitivity. In LC/ESI-MS/MS, chemical derivatization is often used to enhance the detection sensitivity. Derivatization improves the chromatographic separation, and enhances the mass spectrometric ionization efficiency and MS/MS detectability. In this review, an overview of the derivatization reagents which have been applied to LC/ESI-MS/MS is presented, focusing on the applications to low molecular weight compounds.

  2. Determination of nicotine, cotinine and caffeine in meconium using high-performance liquid chromatography.

    PubMed

    Baranowski, J; Pochopień, G; Baranowska, I

    1998-04-10

    A high-performance liquid chromatographic method with diode-array detection for the determination of nicotine and its metabolites, cotinine and caffeine, in meconium is described. This method is suitable to assess foetus exposure to tobacco smoke. The analytes were extracted by solid-phase extraction before chromatography. From among 30 meconium samples 11 were positive for cotinine (20-86 ng/g) and 27 for caffeine (10-45 ng/g). No nicotine was present in the samples because of its rapid metabolism into cotinine.

  3. [Determination of organic acids in fermentation broth of spiramycin by high performance liquid chromatography].

    PubMed

    Li, You-yuan; Chen, Chang-hua; Tao, Ping

    2002-01-01

    A method for determining organic acids in spiramycin fermentation broth by high performance liquid chromatography is described. The operating conditions were Zorbax 300-SB C18 column (5 microns, 4.6 mm i.d. x 15 cm) at 35 degrees C, 0.01 mol/L phosphoric acid buffer solution (pH 2.32) and methanol as mobile phase at a flow rate of 0.6 mL/min and UV detection at 210 nm. The relative standard deviations were 0.33%-0.10% and the recoveries were 99.95%-100.08%. It's a simple, rapid and accurate method.

  4. Purification of Mouse Monoclonal Immunoglobulin M by Ion-Exchange Liquid Chromatography

    DTIC Science & Technology

    1989-01-01

    Retention times of the IgM peaks were 27 min for each. The IgM concentration of the pooled peak fractions was determined by ELISA with mouse myeloma IgM as...PURIFICATION OF MOUSE MONOCLONAL IMMUNOGLOBULIN M BY ION-EXCHANGE LIQUID CHROMATOGRAPHY SARA W. ROTHMAN1 , MARY KAY GENTRY 1, ROGER D. GAWNE 1...antibodies have been difficult to purify. By eluting with a gradient of increasing salt and decreasing pH, we succeeded in highly purifying mouse

  5. 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 β-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.

  6. Determination of glycerol in oils and fats using liquid chromatography chloride attachment electrospray ionization mass spectrometry.

    PubMed

    Jin, Chunfen; Viidanoja, Jyrki

    2017-01-15

    Existing liquid chromatography - mass spectrometry method for the analysis of short chain carboxylic acids was expanded and validated to cover also the measurement of glycerol from oils and fats. The method employs chloride anion attachment and two ions, [glycerol+(35)Cl](-) and [glycerol+(37)Cl](-), as alternative quantifiers for improved selectivity of glycerol measurement. The averaged within run precision, between run precision and accuracy ranged between 0.3-7%, 0.4-6% and 94-99%, respectively, depending on the analyte ion and sample matrix. Selected renewable diesel feedstocks were analyzed with the method.

  7. 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.

  8. Stationary phase optimized selectivity liquid chromatography: Basic possibilities of serially connected columns using the "PRISMA" principle.

    PubMed

    Nyiredy, Sz; Szucs, Zoltán; Szepesy, L

    2007-07-20

    A new procedure (stationary phase optimized selectivity liquid chromatography: SOS-LC) is described for the optimization of the HPLC stationary phase, using serially connected columns and the principle of the "PRISMA" model. The retention factors (k) of the analytes were determined on three different stationary phases. By use of these data the k values were predicted applying theoretically combined stationary phases. These predictions resulted in numerous intermediate theoretical separations from among which only the optimal one was assembled and tested. The overall selectivity of this separation was better than that of any individual base stationary phase. SOS-LC is independent of the mechanism and the scale of separation.

  9. High performance liquid chromatography and electron spin resonance studies of some sugar-nitroxide solutions

    SciTech Connect

    Angel, J.P.; Thiery, C.; Battesti, C.; Vincent, P.; Raffi, J.

    1985-01-01

    Radicals induced by gamma irradiation of alpha-D-glucose, 1-0-methyl-alpha-D-glucose and maltose, in the solid state, have been studied by the spin-trapping method. High performance liquid chromatography of sugar-nitroxide solutions, combined with electron spin resonance analysis, revealed nine, eight and twelve discernible radical species, the majority of them being indiscernible by the direct spin-trapping method. Tentative correlations and assignments of chemical structures are discussed. 9 references, 4 figures, 3 tables.

  10. Novel devices for solvent delivery and temperature programming designed for capillary liquid chromatography.

    PubMed

    Coutinho, Lincoln Figueira Marins; Nazario, Carlos Eduardo Domingues; Monteiro, Alessandra Maffei; Lanças, Fernando Mauro

    2014-08-01

    Analyses in chromatographic systems able to save mobile and stationary phases without reducing efficiency and resolution are of current interest. These advantages regarding savings have challenged us to develop a system dedicated to miniaturized liquid chromatography. This paper reports on the development of a high-pressure syringe-type pump, an oven able to perform isothermal and temperature programming and a software program to control these chromatographic devices. The experimental results show that the miniaturized system can generate reproducible and accurate temperature and flow rate. The system was applied to the separation of statins and tetracylines and showed excellent performance.

  11. Rapid determination of beta-aminoisobutyric acid by reversed-phase high-performance liquid chromatography.

    PubMed

    Ladrón de Guevara, O; Cortinas de Nava, C; Padilla, P; Espinosa, J; Cebrian, M; García, L

    1990-06-08

    For the determination of beta-aminoisobutyric acid (BAIBA) in urine samples in which the beta-alanine concentrations are higher than those of BAIBA, the resolution between these two amino acids, separated by reversed-phase liquid chromatography on an octadecylsilane column, was optimized. The chromatographic analysis included precolumn derivatization of amino acids with o-phthalaldehyde, followed by a 15-min isocratic elution and detection at 340 nm. Because of its simplicity, this method should be useful for monitoring urinary excretion of BAIBA.

  12. Pressurized nano-liquid-junction interface for coupling capillary electrochromatography and nano-liquid chromatography with mass spectrometry.

    PubMed

    D'Orazio, Giovanni; Fanali, Salvatore

    2013-11-22

    A new nano-liquid-junction interface for coupling both capillary electrochromatography (CEC) or nano-liquid chromatography (nano-LC) with mass spectrometry (MS) was studied. The interface was a small T piece of polymeric material where capillary column and tip capillary were positioned at 180° while the third exit (at 90°) was occupied by a capillary delivering a liquid-assisting spray ionization for CEC experiments or by the electrode for the high voltage spray for nano-LC. Experiments were carried out analyzing mixtures of some organophosphorus pesticides (OPPs) or anti-inflammatory and related acidic drugs with MS detection in positive or negative ion mode, respectively. Analyzed OPPs compounds were baseline resolved utilizing the novel interface in both nano-LC and CEC obtaining good sensitivity and repeatability. For CEC-MS, the limits of detection ranged between 0.03 and 6.80 μg/mL and the intra-day repeatability was RSD <3.8% and <13% for the retention times and peak areas, respectively. The interface was easy to handle and good reproducibility, between 2.5 and 3.5% for the retention time and <10% for the efficiencies, was obtained when the interface was installed by two different analysts. Furthermore, it could be used for both CEC and nano-LC.

  13. Determination of tocopherols and tocotrienols in cereals by pressurized liquid extraction-liquid chromatography-mass spectrometry.

    PubMed

    Bustamante-Rangel, M; Delgado-Zamarreño, M M; Sánchez-Pérez, A; Carabias-Martínez, R

    2007-03-28

    A rapid analytical method including pressurized liquid extraction (PLE) and liquid chromatography-electrospray ionisation-mass spectrometry (LC-ESI-MS) has been developed for the determination of tocopherols and tocotrienols in cereals. The pressurized liquid extraction parameters were optimized in order to maximize the extraction efficiency. The use of methanol as extraction solvent at a temperature of 50 degrees C and a pressure of 110 bar, using one cycle of extraction with a static time of 5 min, provided the best results. A good LC separation was achieved using a C(18) column and a solution of 6.0 mM ammonia in methanol/water (97:3, v/v) as the mobile phase at a flow rate of 0.2 mL min(-1). MS coupling with an ESI interface in the negative ion mode was used as the detection technique. In the present work, it is shown that the addition of a base to the mobile phase is required to enhance the ionization of tocopherols and tocotrienols in negative ion mode electrospray ionization. The applicability of the method to cereal samples was confirmed. The reproducibility of the procedure was good, with relative standard deviations in the 6-10% range. The recoveries of added tocopherols from cereal samples ranged from 91 to 109%.

  14. Salting-out homogenous extraction followed by ionic liquid/ionic liquid liquid-liquid micro-extraction for determination of sulfonamides in blood by high performance liquid chromatography.

    PubMed

    Liu, Zhongling; Yu, Wei; Zhang, Hanqi; Gu, Fanbin; Jin, Xiangqun

    2016-12-01

    Salting-out homogenous extraction followed by ionic liquid/ionic liquid dispersive liquid-liquid micro-extraction system was developed and applied to the extraction of sulfonamides in blood. High-performance liquid chromatography was applied to the determination of the analytes. The blood sample was centrifuged to obtain the serum. After the proteins in the serum were removed in the presence of acetonitrile, ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, dipotassium hydrogen phosphate, ionic liquid 1-Hexyl-3-methylimidazolium hexafluorophosphate were added into the resulting solution. After the resulting mixture was ultrasonically shaken and centrifuged, the precipitate was separated. The acetonitrile was added in the precipitate and the analytes were extracted into the acetonitrile phase. The parameters affecting the extraction efficiency, such as volume of ionic liquid, amount of dipotassium hydrogen phosphate, volume of dispersant, extraction time and temperature were investigated. The limits of detection of sulfamethizole (STZ), sulfachlorpyridazine (SCP), sulfamethoxazole (SMX) and Sulfisoxazole (SSZ) were 4.78, 3.99, 5.21 and 3.77μgL(-1), respectively. When the present method was applied to the analysis of real blood samples, the recoveries of analytes ranged from 90.0% to 113.0% and relative standard deviations were lower than 7.2%.

  15. Quantitative Analysis of Tetramethylenedisulfotetramine ("Tetramine") Spiked into Beverages by Liquid Chromatography Tandem Mass Spectrometry with Validation by Gas Chromatography Mass Spectrometry

    SciTech Connect

    Owens, J; Hok, S; Alcaraz, A; Koester, C

    2008-11-13

    Tetramethylenedisulfotetramine, commonly known as tetramine, is a highly neurotoxic rodenticide (human oral LD{sub 50} = 0.1 mg/kg) used in hundreds of deliberate food poisoning events in China. Here we describe a method for quantitation of tetramine spiked into beverages, including milk, juice, tea, cola, and water and cleaned up by C8 solid phase extraction and liquid-liquid extraction. Quantitation by high performance liquid chromatography tandem mass spectrometry (LC/MS/MS) was based upon fragmentation of m/z 347 to m/z 268. The method was validated by gas chromatography mass spectrometry (GC/MS) operated in SIM mode for ions m/z 212, 240, and 360. The limit of quantitation was 0.10 {micro}g/mL by LC/MS/MS versus 0.15 {micro}g/mL for GC/MS. Fortifications of the beverages at 2.5 {micro}g/mL and 0.25 {micro}g/mL were recovered ranging from 73-128% by liquid-liquid extraction for GC/MS analysis, 13-96% by SPE and 10-101% by liquid-liquid extraction for LC/MS/MS analysis.

  16. Saffron authentication based on liquid chromatography high resolution tandem mass spectrometry and multivariate data analysis.

    PubMed

    Rubert, Josep; Lacina, Ondrej; Zachariasova, Milena; Hajslova, Jana

    2016-08-01

    Saffron is one of the oldest and most expensive spices, which is often target of fraudulent activities. In this research, a new strategy of saffron authentication based on metabolic fingerprinting was developed. In the first phase, a solid liquid extraction procedure was optimized, the main aim was to isolate as maximal representation of small molecules contained in saffron as possible. In the second step, a detection method based on liquid chromatography coupled with high-resolution mass spectrometry was developed. Initially, principal component analysis (PCA) revealed clear differences between saffron cultivated and packaged in Spain, protected designation of origin (PDO), and saffron packaged in Spain of unknown origin, labeled Spanish saffron. Afterwards, orthogonal partial least square discriminant analysis (OPLS-DA) was favorably used to discriminate between Spanish saffron. The tentative identification of markers showed glycerophospholipids and their oxidized lipids were significant markers according to their origin.

  17. Quantitative analysis of vitamin D3 in a feed using normal phase high pressure liquid chromatography.

    PubMed

    Cohen, H; Lapointe, M

    1979-09-01

    A procedure is described for the separation and quantification of Vitamin D3 from different feeds and premixes. The study was conducted, first using a liquid partition step as a preliminary clean-up after extraction, then chromatography on activated Silica gel 60 before final analysis on a high pressure liquid chromatograph (HPLC) using a LiChrosorb NH2 (10 mu) column and a variable wavelength UV detector set at 264 nm. Total analysis on the HPLC was achieved in fifteen minutes. The detector response curve for an authentic D3 standard was linear using peak areas with a minimum detectable amount being 5 ng. The overall percent recovery of D3 in feeds was 94.4 +/- 2.4%. The minimum detectable amount of D3 in animal feeds was found to be in the region of 2,000 I.U./kg.

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

    SciTech Connect

    Ambrose, Diana

    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.

  19. Determination of nonylphenol polyethoxylates in household detergents by high-performance liquid chromatography.

    PubMed

    Cheng, Chin-Yuan; Ding, Wang-Hsien

    2002-08-30

    Preliminary survey results of the content of nonylphenol polyethoxylates (NPEOs) in various household detergents sold in Taiwan are presented. This survey was conducted to elucidate the concentration of NPEOs in household detergents and support pollution prevention and control programs. The concentrations of NPEOs in detergents and cleaners were determined by HPLC with a C8 reversed-phase column and equipped with fluorescence detection. The accuracy and precision of the method was validated and was successfully applied to determine concentrations of NPEOs in household detergents. The results show that NPEOs were detected in 41% of 90 household detergents at concentrations from 0.2 to 21%. The highest concentration of NPEOs (21%) was detected in a laundry liquid especially designed for washing socks. Reversed-phase liquid chromatography connected with electrospray mass spectrometry confirmed the results.

  20. Quantification of candidate prostate cancer metabolite biomarkers in urine using dispersive derivatization liquid-liquid microextraction followed by gas and liquid chromatography-mass spectrometry.

    PubMed

    Shamsipur, Mojtaba; Naseri, Mohammad Taghi; Babri, Mehran

    2013-01-01

    A simple, rapid and sensitive method based on dispersive derivatization liquid-liquid microextraction (DDLLME) combined with gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) was developed and validated for the determination of prostate cancer metabolite biomarkers, including sarcosine, alanine, leucine and proline, in human urine samples. Dispersive derivatization using isobutyl chloroformate has been successfully employed to identify the amino acids of interest in ng mL(-1) concentrations. Under the optimum experimental conditions, the detection limits of the amino acids were in the range of 0.05-0.1 ng mL(-1). The enrichment factor and relative recovery for the target amino acids were in the range of 140-155 and 93.8-106%, respectively. The proposed method showed good linearity (correlation coefficients >0.997), and good intra-day (below 7%) and inter-day precision (below 10%). This protocol provides a rapid, simple, selective and sensitive tool to quantify sarcosine and endogenous urinary metabolite for prostate cancer diagnosis and for a screening test.

  1. Determination of field-incurred pyrimethanil residues in persimmon (Diospyros kaki Linn) by liquid chromatography.

    PubMed

    Shim, Jae-Han; Abd El-Aty, A M; Choi, Jeong-Heui; Kang, Cheol-Ah

    2007-12-01

    Field trials have been carried out to determine the residues of the fungicide pyrimethanil in persimmon (Diospyros kaki Linn) after field treatment. Three treatments using pyrimethanil (PYR 30% WP) were carried out on persimmon trees at a recommended dose rate: the former was sprayed at two different times at 30 and 21 days prior to harvesting; the second was sprayed three times at 40, 30 and 21 days prior to harvesting; and the third was sprayed four times at 40, 30, 21 and 14 days prior to harvesting. The analysis was based on liquid-liquid extraction and solid-phase extraction followed by liquid chromatography with ultraviolet detection at 268 nm. Pyrimethanil was confirmed by high-performance liquid chromatography-mass spectrometry HPLC-MS in the selected ion monitoring mode. The method was validated with spiked fruit samples at concentrations of 0.1 and 0.4 ppm. Average recoveries (three replicates) ranged from 87.1 to 92.1% with relative standard deviations between 4.5 and 11.98%. The calculated limit of detection was 0.02 ppm and the limit of quantitation was 0.07 ppm. After two, three or four applications, pyrimethanil residues on persimmon averaged 0.44, 0.48 or 0.53 ppm, respectively; all of these values were below the maximum residue level established by the Korean Food and Drug Administration (5.0 ppm). This indicates that pyrimethanil residues declined to a level well below the maximum residue level within the 14 day period between the last application and harvesting.

  2. Single-step electrodeposition of CIS thin films with the complexing agent triethanolamine

    NASA Astrophysics Data System (ADS)

    Chiu, Yu-Shuen; Hsieh, Mu-Tao; Chang, Chih-Min; Chen, Chun-Shuo; Whang, Thou-Jen

    2014-04-01

    Some difficulties have long been encountered by single-step electrodeposition such as the optimization of electrolyte composition, deposition potentials, deposition time, and pH values. The approach of introducing ternary components into single-step electrodeposition is rather challenging especially due to the different values of the equilibrium potential for each constituent. Complexing agents play an important role in single-step electrodeposition of CuInSe2 (CIS), since the equilibrium potential of every constituent can be brought closer to each other when complexing agents are employed. In this work, single-step electrodeposition of CIS was enhanced by adding triethanolamine (TEA) into deposition bath, the CIS thin films were improved consequently in the form of polycrystalline cauliflower structures through the examination of SEM images and XRD patterns. The optimum composition of the solution for single-step electrodeposition of CIS is found to be 5 mM CuCl2, 22 mM InCl3, and 22 mM SeO2 at pH 1.5 with 0.1 M TEA. The structures, compositions, and morphologies of as-deposited and of annealed films were investigated.

  3. Screening antiallergic components from Carthamus tinctorius using rat basophilic leukemia 2H3 cell membrane chromatography combined with high-performance liquid chromatography and tandem mass spectrometry.

    PubMed

    Han, Shengli; Huang, Jing; Cui, Ronghua; Zhang, Tao

    2015-02-01

    Carthamus tinctorius, used in traditional Chinese medicine, has many pharmacological effects, such as anticoagulant effects, antioxidant effects, antiaging effects, regulation of gene expression, and antitumor effects. However, there is no report on the antiallergic effects of the components in C. tinctorius. In the present study, we investigated the antiallergic components of C. tinctorius and its mechanism of action. A rat basophilic leukemia 2H3/cell membrane chromatography coupled online with high-performance liquid chromatography and tandem mass spectrometry method was developed to screen antiallergic components from C. tinctorius. The screening results showed that Hydroxysafflor yellow A, from C. tinctorius, was the targeted component that retained on the rat basophilic leukemia 2H3/cell membrane chromatography column. We measured the amount of β-hexosaminidase and histamine released in mast cells and the key markers of degranulation. The release assays showed that Hydroxysafflor yellow A could attenuate the immunoglobulin E induced release of allergic cytokines without affecting cell viability from 1.0 to 50.0 μM. In conclusion, the established rat basophilic leukemia 2H3 cell membrane chromatography coupled with online high-performance liquid chromatography and tandem mass spectrometry method successfully screened and identified Hydroxysafflor yellow A from C. tinctorius as a potential antiallergic component. Pharmacological analysis elucidated that Hydroxysafflor yellow A is an effective natural component for inhibiting immunoglobulin E-antigen-mediated degranulation.

  4. Analysis of lignans in Magnoliae Flos by turbulent flow chromatography with online solid-phase extraction and high-performance liquid chromatography with tandem mass spectrometry.

    PubMed

    Zhou, Xuan; Chen, Cen; Ye, Xiaolan; Song, Fenyun; Fan, Guorong; Wu, Fuhai

    2016-04-01

    In this study, a method coupling turbulent flow chromatography with online solid-phase extraction and high-performance liquid chromatography with tandem mass spectrometry was developed for analyzing the lignans in Magnoliae Flos. By the online pretreatment of turbulent flow chromatography solid-phase extraction, the impurities removal and analytes concentration were automatically processed, and the lignans were separated rapidly and well. Seven lignans of Magnoliae Flos including epieudesmin, magnolin, 1-irioresinol-B-dimethyl ether, epi-magnolin, fargesin aschantin, and demethoxyaschantin were identified by comparing their retention behavior, UV spectra, and mass spectra with those of reference substances or literature data. The developed method was validated, and the good results showed that the method was not only automatic and rapid, but also accurate and reliable. The turbulent flow chromatography with online solid-phase extraction and high-performance liquid chromatography with tandem mass spectrometry method holds a high potential to become an effective method for the quality control of lignans in Magnoliae Flos and a useful tool for the analysis of other complex mixtures.

  5. 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

  6. Quantification of Quercetin and Rutin from Benincasa hispida Seeds and Carissa Congesta Roots by High-performance Thin Layer Chromatography and High-performance Liquid Chromatography

    PubMed Central

    Doshi, Gaurav Mahesh; Une, Hemant Devidas

    2016-01-01

    Objective: In Indian Ayurvedic system, Benincasa hispida (BH) and Carissa congesta (CC) are well-known plants used for major and minor ailments. BH has been regarded as Kushmanda, whereas CC has been used in immune-related disorders of the human system. Quercetin and rutin identified from the vast plethora of plant extracts have proved to possess ethnopharmacological relevance. Materials and Methods: In present studies, we have determined quercetin and rutin in terms of percentage in BH seeds and CC roots by high-performance thin layer chromatography (HPTLC) and high-performance liquid chromatography (HPLC). After extraction and phytochemical screening, the extracts were subjected to quantification for the presence of quercetin and rutin by HPTLC and HPLC. Results: HPTLC showed quercetin as 44.60, 27.13% and rutin as 32.00, 36.31% w/w, whereas HPLC revealed quercetin as 34.00, 35.00% and rutin as 21.99, 45.03% w/v in BH and CC extracts, respectively. Conclusion: The BH and CC extracts have elucidated peaks that were corresponding with standard peaks on undertaking chromatographic studies. SUMMARY Quercetin and rutin are isolated from BH seeds and CC roots by High Performance. Thin Layer Chromatography and High Performance Liquid Chromatography. HPTLC revealed presence of quercetin as 44.60, 27.13 % and rutin as 32.00, 36.31 % w/w. HPLC revealed presence of quercetin as 34.00, 35.00 % and rutin as 21.99, 45.03 % w/v. Abbreviation Used: HPTLC: High Performance Thin Layer Chromatography; HPLC: High Pressure Liquid Chromatography, UV: Ultraviolet, CC: Carissa congesta, BH: Benincasa hispida PMID:26941534

  7. Characterization of peak capacity of microbore liquid chromatography columns using gradient kinetic plots.

    PubMed

    Hetzel, Terence; Blaesing, Christina; Jaeger, Martin; Teutenberg, Thorsten; Schmidt, Torsten C

    2017-02-17

    The performance of micro-liquid chromatography columns with an inner diameter of 0.3mm was investigated on a dedicated micro-LC system for gradient elution. Core-shell as well as fully porous particle packed columns were compared on the basis of peak capacity and gradient kinetic plot limits. The results for peak capacity showed the superior performance of columns packed with sub-2μm fully porous particles compared to 3.0μm fully porous and 2.7μm core-shell particles within a range of different gradient time to column void time ratios. For ultra-fast chromatography a maximum peak capacity of 16 can be obtained using a 30s gradient for the sub-2μm fully porous particle packed column. A maximum peak capacity of 121 can be achieved using a 5min gradient. In addition, the influence of an alternative detector cell on the basis of optical waveguide technology and contributing less to system variance was investigated showing an increased peak capacity for all applied gradient time/column void time ratios. Finally, the influence of pressure was evaluated indicating increased peak capacity for maximum performance whereas a limited benefit for ultra-fast chromatography with gradient times below 30s was observed.

  8. Determination of multiple phytohormones in fruits by high-performance liquid chromatography with fluorescence detection using dispersive liquid-liquid microextraction followed by precolumn fluorescent labeling.

    PubMed

    Li, Guoliang; Lu, Shuaimin; Wu, Hongliang; Chen, Guang; Liu, Shucheng; Kong, Xiaojian; Kong, Weiheng; You, Jinmao

    2015-01-01

    Plant hormone determination in food matrices has attracted more and more attention because of their potential risks to human health. However, analytical methods for the analysis of multiple plant hormones remain poorly investigated. In the present study, a convenient, selective, and ultrasensitive high-performance liquid chromatography method for the simultaneous determination of multiple classes of plant hormones has been developed successfully using dispersive liquid-liquid microextraction followed by precolumn fluorescent labeling. Eight plant hormones in fruits including jasmonic acid, 12-oxo-phytodienoic acid, indole-3-acetic acid, 3-indolybutyric acid, 3-indolepropionic acid, gibberellin A3 , 1-naphthylacetic acid, and 2-naphthaleneacetic acid were analyzed by this method. The conditions employed for dispersive liquid-liquid microextraction were optimized systematically. The linearity for all plant hormones was found to be >0.9993 (R(2) values). This method offered low detection limits of 0.19-0.44 ng/mL (at a signal-to-noise ratio of 3), and method accuracies were in the range of 92.32-103.10%. The proposed method was applied to determine plant hormones in five kinds of food samples, and this method can achieve a short analysis time, low threshold levels of detection, and a high specificity for the analysis of targeted plant hormones present at trace level concentrations in complex matrices.

  9. Stir-membrane solid-liquid-liquid microextraction for the determination of parabens in human breast milk samples by ultra high performance liquid chromatography-tandem mass spectrometry.

    PubMed

    Rodríguez-Gómez, Rocío; Roldán-Pijuán, Mercedes; Lucena, Rafael; Cárdenas, Soledad; Zafra-Gómez, Alberto; Ballesteros, Oscar; Navalón, Alberto; Valcárcel, Miguel

    2014-08-08

    In this article, stir-membrane solid-liquid-liquid microextraction (SM-SLLME) is tailored for the analysis of solid matrices and it has been evaluated for the determination of parabens in l breast milk samples. A three-phase microextraction mode was used for the extraction of the target compounds taking advantage of their acid-base properties. The unit allows the simultaneous extraction of the target compounds from the solid sample to an organic media and the subsequent transference of the analytes to an aqueous acceptor phase. The method includes the identification and quantification of the analytes by ultra high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). All the variables involved in the extraction procedure have been accurately studied and optimized. The analytes were detected and quantified using a triple quadrupole mass spectrometer (QqQ). The selection of two specific fragmentation transitions for each compound allowed simultaneous quantification and identification. The method has been analytically characterized on the basis of its linearity, sensitivity and precision. Limits of detection ranged from 0.1 to 0.2ngmL(-1) with precision better than 8%, (expressed as relative standard deviation). Relative recoveries were in the range from 91 to 106% which demonstrated the applicability of the stir-membrane solid-liquid-liquid microextraction for the proposed analytical problem. Moreover, the method has been satisfactorily applied for the determination of parabens in lyophilized breast milk samples from 10 randomly selected individuals.

  10. Rapid determination of some psychotropic drugs in complex matrices by tandem dispersive liquid-liquid microextraction followed by high performance liquid chromatography.

    PubMed

    Asghari, Alireza; Fahimi, Ebrahim; Bazregar, Mohammad; Rajabi, Maryam; Boutorabi, Leila

    2017-03-15

    Simple and rapid determinations of some psychotropic drugs in some pharmaceutical wastewater and human plasma samples were successfully accomplished via the tandem dispersive liquid-liquid microextraction combined with high performance liquid chromatography-ultraviolet detection (TDLLME-HPLC-UV). TDLLME of the three psychotropic drugs clozapine, chlorpromazine, and thioridazine was easily performed through two consecutive dispersive liquid-liquid microextractions. By performing this convenient method, proper sample preconcentrations and clean-ups were achieved in just about 7min. In order to achieve the best extraction efficiency, the effective parameters involved were optimized. The optimal experimental conditions consisted of 100μL of CCl4 (as the extraction organic solvent), and the pH values of 13 and 2 for the donor and acceptor phases, respectively. Under these optimum experimental conditions, the proposed TDLLME-HPLC-UV technique provided a good linearity in the range of 5-3000ngmL(-1) for the three psychotropic drugs with the correlation of determinations (R(2)s) higher than 0.996. The limits of quantification (LOQs) and limits of detection (LODs) obtained were 5.0ngmL(-1) and 1.0-1.5ngmL(-1), respectively. Also the proper enrichment factors (EFs) of 96, 99, and 88 for clozapine, chlorpromazine, and thioridazine, respectively, and good extraction repeatabilities (relative standard deviations below 9.3%, n=5) were obtained.

  11. Preconcentration and determination of ceftazidime in real samples using dispersive liquid-liquid microextraction and high-performance liquid chromatography with the aid of experimental design.

    PubMed

    Razmi, Rasoul; Shahpari, Behrouz; Pourbasheer, Eslam; Boustanifar, Mohammad Hasan; Azari, Zhila; Ebadi, Amin

    2016-11-01

    A rapid and simple method for the extraction and preconcentration of ceftazidime in aqueous samples has been developed using dispersive liquid-liquid microextraction followed by high-performance liquid chromatography analysis. The extraction parameters, such as the volume of extraction solvent and disperser solvent, salt effect, sample volume, centrifuge rate, centrifuge time, extraction time, and temperature in the dispersive liquid-liquid microextraction process, were studied and optimized with the experimental design methods. Firstly, for the preliminary screening of the parameters the taguchi design was used and then, the fractional factorial design was used for significant factors optimization. At the optimum conditions, the calibration curves for ceftazidime indicated good linearity over the range of 0.001-10 μg/mL with correlation coefficients higher than the 0.98, and the limits of detection were 0.13 and 0.17 ng/mL, for water and urine samples, respectively. The proposed method successfully employed to determine ceftazidime in water and urine samples and good agreement between the experimental data and predictive values has been achieved.

  12. [Simultaneous determination of pantothenic acid and D-panthenol in cosmetics by high performance liquid chromatography].

    PubMed

    Mao, Xiqin; Hu, Xia; Pan, Wei

    2010-11-01

    A high performance liquid chromatographic method (HPLC) and sample pretreatment method were developed for the simultaneous determination of pantothenic acid (vitamin B5) and D-panthenol (provitamin B5) in cosmetics with different matrices (including of creams, lotions, aqueous cosmetics, oily cosmetics, wax-based cosmetics, nail polish etc). A liquid-liquid extraction system composed of water and water-immiscible solvent was used to preliminarily separate the target components from other oil-soluble components and surfactants in cosmetics, then macromolecular water-soluble matrices in cosmetics were removed by coprecipitation with potassium ferrocyanide-zinc acetate precipitating agent, and then under acid condition, pantothenic acid and D-panthenol were enriched on a C18 solid-phase extraction sorbent. After the removal of other water-soluble impurities, target components were eluted by 40% methanol and then separated and quantitatively analyzed by high performance liquid chromatography with external standard method. Good linear relationship was achieved in the concentration range of 0.1-10 microg/g for pantothenic acid and D-panthenol. The linear correlation coefficients were separately 0.998 9 and 0.999 6. The average recoveries of the target components in cosmetics were more than 90%. Limit of detection of the method was 30 microg/g and the limit of quantification was 100 microg/g. This method can be used to simultaneously determine pantothenic acid and D-panthenol in cosmetics. The results are accurate and reliable.

  13. Determination of plastic additives in packaging by liquid chromatography coupled to high resolution mass spectrometry.

    PubMed

    Moreta, Cristina; Tena, María-Teresa

    2015-10-02

    A simple and sensitive analytical method for the determination of several plastic additives in multilayer packaging based on solid-liquid extraction (SLE) and ultra-high performance liquid chromatography (UHPLC) coupled to variable wavelength (VWD) and time of flight mass spectrometry (TOF-MS) detectors is presented. The proposed method allows the simultaneous determination of fourteen additives belonging to different families such as antioxidants, slip agents and light stabilizers, as well as two oxidation products in only 9min. The developed method was validated in terms of linearity, matrix effect error, detection and quantification limits, repeatability and intermediate precision. The instrumental method showed satisfactory repeatability and intermediate precision at concentrations closed to LOQ with RSDs less than 7 and 20%, respectively, and LODs until 5000 times more sensitive than other GC-FID and HPLC-VWD methods previously reported. Also, focused ultrasound solid-liquid extraction (FUSLE) was optimized and evaluated to extract plastic additives from packaging. Extraction results obtained by FUSLE and SLE were compared to those obtained by pressurized liquid extraction (PLE). All extraction methods showed excellent extraction efficiency for slip agents, however quantitative recovery of all analytes was achieved only by SLE with just 5ml of hexane for 10h. Finally, the selected method was applied to the analysis of packaging samples where erucamide, Irgafos 168, oxidized Irgafos 168, Irganox 1076 and Irganox 1010 were detected and quantified.

  14. Safety concerns in ultrahigh pressure capillary liquid chromatography using air-driven pumps.

    PubMed

    Xiang, Yanqiao; Maynes, Daniel R; Lee, Milton L

    2003-04-04

    Ultrahigh pressure liquid chromatography (UHPLC) is an emerging technique which utilizes pressures higher than 10,000 p.s.i. to overcome the flow resistance imposed when using very small particles as packing materials in fused-silica capillary columns (1 p.s.i.=6894.76 Pa). This technique has demonstrated exceptionally high separation speeds and chromatographic efficiencies. However, safety is a concern when extremely high pressures are used. In this study, the safety aspects of capillary column rupture during operation were identified and carefully evaluated. First, liquid jets may be formed as a result of blow-out of the on-column frits or from rupture of the capillary at or near the column inlet. Second, incorrect installation of the capillary at the injector, failure of the ferrule used in the capillary connection, or rupture of the capillary can produce high speed projectiles of silica particles or column fragments. Experiments were carried out in the laboratory to produce liquid (water) jets and capillary projectiles using a UHPLC system, and the power density, an important parameter describing water jets in industrial practice, was calculated. Experimental results were in accordance with theoretical calculations. Both indicated that water jets and capillary projectiles under ultrahigh pressures might lead to skin penetration under limited conditions. The use of a plexiglass shroud to cover an initial length of the installed capillary column can eliminate any safety-related concerns about liquid jets or capillary projectiles.

  15. New support for high-performance liquid chromatography based on silica coated with alumina particles.

    PubMed

    Silveira, José Leandro R; Dib, Samia R; Faria, Anizio M

    2014-01-01

    A new material based on silica coated with alumina nanoparticles was proposed for use as a chromatographic support for reversed-phase high-performance liquid chromatography. Alumina nanoparticles were synthesized by a sol-gel process in reversed micelles composed of sodium bis(2-ethylhexyl)sulfosuccinate, and the support material was formed by the self-assembly of alumina layers on silica spheres. Spectroscopic and (29)Si nuclear magnetic resonance results showed evidence of chemical bonds between the alumina nanoparticles and the silica spheres, while morphological characterizations showed that the aluminized silica maintained the morphological properties of silica desired for chromatographic purposes after alumina incorporation. Stability studies indicated that bare silica showed high dissolution (~83%), while the aluminized silica remained practically unchanged (99%) after passing one liter of the alkaline mobile phase, indicating high stability under alkaline conditions. The C18 bonded aluminized silica phase showed great potential for use in high-performance liquid chromatography to separate basic molecules in the reversed-phase mode.

  16. Stationary phase modulation in liquid chromatography through the serial coupling of columns: A review.

    PubMed

    Alvarez-Segura, T; Torres-Lapasió, J R; Ortiz-Bolsico, C; García-Alvarez-Coque, M C

    2016-06-07

    Liquid chromatography with single columns often does not succeed in the analysis of complex samples, in terms of resolution and analysis time. A relatively simple solution to enhance chromatographic resolution is the modulation of the stationary phase through the serial coupling of columns. This can be implemented with any type of column using compatible elution conditions and conventional instruments. This review describes the key features of column coupling and published procedures, where two or more columns were coupled in series to solve separation problems. In all reports, the authors could not resolve their samples with single columns, whereas significant enhancement in chromatographic performance was obtained when the columns were combined. Particularly interesting is the reduction in the analysis time in the isocratic mode, which alleviates the "general elution problem" of liquid chromatography, and may represent a stimulus for the proposal of new procedures, especially in combination with mass spectrometric, electrochemical and refractometric detection. Developments proposed to make the serial coupling of columns useful in routine and research laboratories are outlined, including optimisation strategies that facilitate the selection of the appropriate column combination and elution conditions (solvent content, flow rate or temperature) in both isocratic and gradient modes. The availability of zero dead volume couplers, able to connect standard columns, and the commercialisation of short columns with multiple lengths, have expanded the possibilities of success.

  17. Approaches to model the retention and peak profile in linear gradient reversed-phase liquid chromatography.

    PubMed

    Baeza-Baeza, J J; Ortiz-Bolsico, C; Torres-Lapasió, J R; García-Álvarez-Coque, M C

    2013-04-05

    The optimisation of the experimental conditions in gradient reversed-phase liquid chromatography requires reliable algorithms for the description of the retention and peak profile. As in isocratic elution, the linear relationship between the logarithm of the retention factor and the solvent contents is only acceptable in relatively small concentration ranges of modifier. However, more complex models may not allow an analytical integration of the general equation for gradient elution. Alternative approaches for modelling the retention in linear gradient elution are here proposed. Those based on the quadratic logarithmic model and a model proposed for normal liquid chromatography yielded accurate predictions of the retention time for a wide range of initial concentrations of organic modifier and gradient slopes, with errors usually below 1-2%. Based on the half-width changes of chromatographic peaks along one or more gradients, an approach is also reported to predict the peak profile with low errors (usually below 2-3%). The proposed approaches were applied to two sets of probe compounds (diuretics and flavonoids), eluted with acetonitrile-water gradients. The changes in retention and peak shape in isocratic and gradient elution are illustrated through diagrams that define triangular regions including all possible values of retention factors or peak half-widths (or widths) inside the selected working ranges.

  18. Hb A1c Separation by High Performance Liquid Chromatography in Hemoglobinopathies

    PubMed Central

    Chandrashekar, Vani

    2016-01-01

    Hb A1c measurement is subject to interference by hemoglobin traits and this is dependent on the method used for determination. In this paper we studied the difference between Hb A1c measured by HPLC in hemoglobin traits and normal chromatograms. We also studied the correlation of Hb A1c with age. Hemoglobin analysis was carried out by high performance liquid chromatography. Spearman's rank correlation was used to study correlation between A1c levels and age. Mann-Whitney U test was used to study the difference in Hb A1c between patients with normal hemoglobin and hemoglobin traits. A total of 431 patients were studied. There was positive correlation with age in patients with normal chromatograms only. No correlation was seen in Hb E trait or beta thalassemia trait. No significant difference in Hb A1c of patients with normal chromatograms and patients with hemoglobin traits was seen. There is no interference by abnormal hemoglobin in the detection of A1c by high performance liquid chromatography. This method cannot be used for detection of A1c in compound heterozygous and homozygous disorders. PMID:26989559

  19. Detection of various freshwater cyanobacterial toxins using ultra-performance liquid chromatography tandem mass spectrometry.

    PubMed

    Oehrle, Stuart A; Southwell, Ben; Westrick, Judy

    2010-05-01

    Several freshwater cyanobacteria species have the capability to produce toxic compounds, frequently referred to as cyanotoxins. The most prevalent of these cyanotoxins is microcystin LR. Recognizing the potential health risk, France, Italy, Poland, Australia, Canada, and Brazil have set either standards or guidelines for the amount of microcystin LR permissible in drinking water based on the World Health Organization guideline of one microg/L of microcystin LR. Recently, the United States Environmental Protection Agency has begun to evaluate the occurrence and health effects of cyanotoxins and their susceptibility to water treatment under the Safe Drinking Water Act through the Contaminant Candidate List (CCL). A recent update of the Contaminant Candidate List focuses research and data collection on the cyanotoxins microcystin LR, anatoxin-a, and cylindrospermopsin. Liquid Chromatography/Tandem-Mass Spectrometry (LC/MS/MS) is a powerful tool for the analysis of various analytes in a wide variety of matrices because of its sensitivity and selectivity. The use of smaller column media (sub 2 microm particles) was investigated to both improve the speed, sensitivity and resolution, and to quantify the CCL cyanotoxins, in a single analysis, using Ultra-Performance Liquid Chromatography (UPLC) combined with tandem mass spectrometry. Natural waters and spiked samples were analyzed to show proof-of-performance. The presented method was able to clearly resolve each of the cyanotoxins in less than eight minutes with specificity and high spike recoveries.

  20. Muramic Acid Measurements for Bacterial Investigations in Marine Environments by High-Pressure Liquid Chromatography

    PubMed Central

    Mimura, Toru; Romano, Jean-Claude

    1985-01-01

    Muramic acid, a constituent of procaryotic cell walls, was assayed by high-pressure liquid chromatography in samples from several marine environments (water column, surface microlayer, and sediment) and a bacterial culture. It is used as a microbial biomass indicator. The method gave a good separation of muramic acid from interfering compounds with satisfactory reproducibility. A pseudomonad culture had a muramic acid content of 4.7 × 10−10 to 5.3 × 10−10 μg per cell during growth. In natural water samples, highly significant relationships were found between muramic acid concentrations and bacterial numbers for populations of 108 to 1011 cells per liter. The muramic acid content in natural marine water decreased from 5.3 × 10−10 to 1.6 × 10−10 μg per cell with increasing depth. In coastal sediments exposed to sewage pollution, concentrations of muramic acid, ATP, organic carbon, and total amino acids displayed a parallel decrease with increasing distance from the sewage outlet. Advantages of muramic acid measurement by high-pressure liquid chromatography are its high sensitivity and reduction of preparation steps, allowing a short time analysis. PMID:16346848

  1. Determination of acrylamide in potato chips and crisps by high-performance liquid chromatography.

    PubMed

    Gökmen, Vural; Senyuva, Hamide Z; Acar, Jale; Sarioğlu, Kemal

    2005-09-23

    A simple and rapid method using liquid chromatography coupled to diode array detection (LC-DAD) was developed for the determination of acrylamide in potato-based foods at low levels. The method entails extraction of acrylamide with methanol, purification with Carrez I and II solutions, evaporation and solvent change to water, and cleanup with a Oasis HLB solid-phase extraction (SPE) cartridge. The final extract was analyzed by LC-DAD for quantification and by liquid chromatography coupled to mass spectrometry (LC-MS) for confirmation. The chromatographic separations were performed on a hydrophilic and a hydrophobic interaction columns having good retention of acrylamide under 100% aqueous flow conditions (k' 3.67 and 2.54, respectively). The limit of quantitation was estimated to be 4.0 microg/kg based on the signal-to-noise ratio of 3 recorded at 226 nm. Recoveries of acrylamide from potato chips samples spiked at levels of 250, 500 and 1000 (n = 4 for each level) microg/kg ranged between 92.8 and 96.2% with relative standard deviations of less than 5%. The results of this study revealed that a conventional LC instrument coupled to DAD can also be used accurately and precisely, as an alternative to tandem LC-MS methods for the determination of acrylamide in potato-based foods.

  2. Determination of Imazaquin and its metabolite by liquid chromatography-quadrupole-time of flight tandem mass.

    PubMed

    Yao, H B; Han, G J; Liu, G X; Xie, Y; Wang, C H

    2010-08-01

    A method consisting of solvent extraction followed by liquid chromatography-quadrupole-time of flight- tandem mass spectrometry analysis was developed for the identification of Imazaquin and its metabolite. The relationships between detector response and sample concentrations showed a high degree of linearity (r > 0.998) over the range 0.03-10 microg/g. The recoveries obtained were in the acceptable range of 86%-104% between spiked. The relative standard deviation of this method was 6.4%-17.1%. A 35-day study of Imazaquin degradation was taken in agricultural soil from Binzhou, China. The degradation followed first order kinetics (C = 0.7672e(-0.0774t)), with half-life of less than 8.5 days. Investigation of the by-products from liquid chromatography-quadrupole-time of flight- tandem mass spectrometry has shown that there were four important metabolites 4-methylene-2-(quinolin-2-yl)-1H-imidazol-5(4H)-one, quinoline-3-carbaldehyde, 1-amino-2,3-dimethyl-1-oxobutan-2-ylium and 1H-[1,2]oxazino[4,5-b]quinolin-1-one in the degradation process. The accurate mass measurements error was 5 ppm in this study. The method was successfully applied to the analysis of imazaquin and its metabolite residues in soil.

  3. Determination of bromate in drinking water by ultraperformance liquid chromatography-tandem mass spectrometry.

    PubMed

    Alsohaimi, Ibrahim Hotan; Alothman, Zeid Abdullah; Khan, Mohammad Rizwan; Abdalla, Mohammad Abulhassan; Busquets, Rosa; Alomary, Ahmad Khodran

    2012-10-01

    Bromate is a byproduct formed as a result of disinfection of bromide-containing source water with ozone or hypochlorite. The International Agency for Research on Cancer has recognized bromate as a possible human carcinogen, thus it is essential to determine in drinking water. Present work highlights a development of sensitive and fast analytical method for bromate determination in drinking water by using ultraperformance liquid chromatography-tandem mass spectrometry. The quality parameters of the developed method were established, obtaining very low limit of detection (0.01 ng/mL), repeatability and reproducibility have been found to be less than 3% in terms of relative standard deviation when analyzing a bromate standard at 0.05 μg/mL with 0.4 min analysis time. Developed method was applied for the analysis of metropolitan and bottled water from Saudi Arabia; 22 samples have been analyzed. Bromate was detected in the metropolitan water samples (from desalinization source) at concentrations ranging between 3.43 and 75.04 ng/mL and in the bottled water samples at concentrations ranging between 2.07 and 21.90 ng/mL. Moreover, in comparison to established analytical methods such as liquid chromatography-tandem mass spectrometry, the proposed method was found to be very sensitive, selective and rapid for the routine analysis of bromate at low level in drinking water.

  4. Analysis of amprolium by hydrophilic interaction liquid chromatography-tandem mass spectrometry.

    PubMed

    Martínez-Villalba, Anna; Moyano, Encarnación; Galceran, M Teresa

    2010-09-10

    We present a fast liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the analysis of the coccidiostat amprolium in food samples. Tandem mass spectrometry in a triple quadrupole was used for quantitative purposes, and the information from multiple-stage mass spectrometry in an ion-trap mass analyzer contributed to fragmentation studies. Hydrophilic interaction liquid chromatography (HILIC) in a Fused-Core column using isocratic elution (acetonitrile:formic acid/ammonium formate buffer pH 4, 50 mM (60:40)) successfully analyzed this compound in less than 3 min. The HILIC system was coupled to heated electrospray-MS/MS using highly selective-selected reaction monitoring (H-SRM) to improve sensitivity and selectivity for the analysis of amprolium, after a simple sample treatment based on an "extract and shoot" strategy. Accurate mass measurements were performed to identify the interfering compound responsible for causing matrix ion enhancement in the signal of amprolium. The addition of l-carnitine (the interfering compound) (1 microg L(-1)) to standards and sample extracts allowed the use of the external calibration method for quantitative purposes. The LC-MS/MS (H-SRM) method showed good precision (relative standard deviation, RSD, lower than 13%), accuracy and linearity and allowed the determination of amprolium down to the ppb level (LODs between 0.1 and 0.6 microg kg(-1)).

  5. Analysis of urine for cysteine, cysteinylglycine, and homocysteine by high-performance liquid chromatography.

    PubMed

    Kuśmierek, K; Głowacki, R; Bald, E

    2006-07-01

    A new analytical method is proposed for simultaneous determination, by liquid chromatography, of the three main urinary thiols-cysteine, cysteinylglycine, and homocysteine. To measure the total amount of these thiols urine is reduced with sodium borohydride, to convert disulfides to thiols which are then derivatized with 2-chloro-1-methylquinolinium tetrafluoroborate. Separation and quantitation of the 2-S-quinolinium thiol derivatives formed were achieved by high-performance liquid chromatography with detection at 355 nm. Validation showed the method enabled reliable simultaneous determination of these aminothiols in urine. The calibration graphs for each analyte, obtained by use of normal urine spiked with increasing amounts of cysteine, cysteinylglycine, and homocysteine, were linear (R2 > or = 0.997) over the range covering most practical situations. The recovery of the assay was 98-100% and sensitivity was 0.12-0.25 micromol L(-1). The method was applied to 91 different samples of normal urine to establish reference values for the aminothiols, normalized on creatinine.

  6. Serotonin metabolism in rat skin: characterization by liquid chromatography-mass spectrometry.

    PubMed

    Semak, Igor; Korik, Elena; Naumova, Marya; Wortsman, Jacobo; Slominski, Andrzej

    2004-01-01

    We have recently uncovered the full expression of novel cutaneous serotoninergic and melatoninergic systems in the human and hamster skin. In this work, we have characterized serotonin metabolism in the rat skin using liquid chromatography-mass spectrometry and found that serotonin undergoes acetylation in the presence of acetyl coenzyme A. Inhibition of serotonin acetylation with Cole bisubstrate inhibitor shows that rat skin expresses both arylalkylamine and arylamine N-acetyltransferase activities. The serotonin degradation product-5-hydroxyindole acetic acid is also detected and pargyline (monoaminooxidase inhibitor) suppresses almost completely 5-hydroxyindole acetic acid accumulation. Together with previous data, the present study clearly demonstrates that biotransformation of serotonin in mammalian skin follows two alternate pathways. In the first pathway, serotonin is acetylated by arylalkylamine and arylamine N-acetyltransferases to generate the precursor of melatonin. Alternately, serotonin may undergo oxidative deamination by monoaminooxidase followed by enzymatic degradation by aldehyde dehydrogenase into 5-hydroxyindole acetic acid, which is presumably devoid of biological activity. Thus, the current methodological development of a liquid chromatography-mass spectrometry-based assay allows rapid resolution of the cutaneous metabolism of serotonin.

  7. High-performance liquid chromatography of histamine and 1-methylhistamine with on-column fluorescence derivatization.

    PubMed

    Saito, K; Horie, M; Nose, N; Nakagomi, K; Nakazawa, H

    1992-03-20

    An on-column fluorometric derivatization method was developed for the determination of histamine and 1-methylhistamine (HMs) by high-performance liquid chromatography. The system for the derivatization consisted only of a commercially available single-plunger pump and a reversed-phase C18 column supported on synthetic polymer with a mobile phase of acetonitrile and alkaline borate buffer solution containing o-phthalaldehyde as a derivatization reagent. It required no additional reaction system as for a post-column derivatization method. Injected HMs might be derivatized to a fluorophore on the inlet site of the high-performance liquid chromatographic column, followed by chromatography on the same column. Optimization of the on-column reaction conditions resulted in a simple and sensitive analytical method for the determination of HMs with excellent reproducibility and linearity of 0.05-5 micrograms/ml of both HMs. Application of this method to the determination of HMs in food samples resulted in a limit of quantification of 0.05 mg/100 g and in a greater than 95% overall mean recovery at a fortification of 0.1 mg/g of both HMs. This method was furthermore applicable to the determination of histamine released from rat peritoneal mast cells.

  8. High-performance liquid chromatography with electrospray ionization ion mobility spectrometry: Characterization, data management, and applications.

    PubMed

    Zühlke, Martin; Riebe, Daniel; Beitz, Toralf; Löhmannsröben, Hans-Gerd; Andreotti, Sandro; Reinert, Knut; Zenichowski, Karl; Diener, Marc

    2016-12-01

    The combination of high-performance liquid chromatography and electrospray ionization ion mobility spectrometry facilitates the two-dimensional separation of complex mixtures in the retention and drift time plane. The ion mobility spectrometer presented here was optimized for flow rates customarily used in high-performance liquid chromatography between 100 and 1500 μL/min. The characterization of the system with respect to such parameters as the peak capacity of each time dimension and of the 2D spectrum was carried out based on a separation of a pesticide mixture containing 24 substances. While the total ion current chromatogram is coarsely resolved, exhibiting coelutions for a number of compounds, all substances can be separately detected in the 2D plane due to the orthogonality of the separations in retention and drift dimensions. Another major advantage of the ion mobility detector is the identification of substances based on their characteristic mobilities. Electrospray ionization allows the detection of substances lacking a chromophore. As an example, the separation of a mixture of 18 amino acids is presented. A software built upon the free mass spectrometry package OpenMS was developed for processing the extensive 2D data. The different processing steps are implemented as separate modules which can be arranged in a graphic workflow facilitating automated processing of data.

  9. Determination of the lipophilicity (log P o/w) of organic compounds by microemulsion liquid chromatography.

    PubMed

    Xu, Liyuan; Li, Liangxing; Huang, Jindian; Yu, Suna; Wang, Jing; Li, Ning

    2015-01-01

    Four microemulsion liquid chromatography (MELC) systems and one micellar liquid chromatography (MLC) system have been evaluated as potential high-throughput screening platforms capable of modeling the partitioning behaviors of drug compounds in an n-octanol/water system and predicting their lipophilicity (i.e., log P values). The microemulsion mobile phases is consisted of sodium dodecyl sulfate (SDS), butanol, octane, heptanes, octanol and water. A linear solvation energy relationship (LSER)-based method was used to compare the MELC and MLC systems, as well as several other biochemical systems, and to identify the optimal system by comparing their Euclidean distances with the LSER coefficients. The most effective MELC system had a mobile phase consisting of 3.0% (w/w) SDS, 6.0% (w/w) butanol, 0.8% (w/w) octanol, and 90.2% (w/w) water (pH 6.4). The results showed that it gave superior results to the other chromatographic systems in terms of its ability to predict the log P values of drug compounds.

  10. Analysis of triacylglycerols on porous graphitic carbon by high temperature liquid chromatography.

    PubMed

    Merelli, Bérangère; De Person, Marine; Favetta, Patrick; Lafosse, Michel

    2007-07-20

    The retention behaviour of several triacylglycerols (TAGs) and fats on Hypercarb, a porous graphitic carbon column (PGC), was investigated in liquid chromatography (LC) under isocratic elution mode with an evaporative light scattering detector (ELSD). Mixtures of chloroform/isopropanol were selected as mobile phase for a suitable retention time to study the influence of temperature. The retention was different between PGC and non-aqueous reversed phase liquid chromatography (NARP-LC) on octadecyl phase. The retention of TAGs was investigated in the interval 30-70 degrees C. Retention was greatly affected by temperature: it decreases as the column temperature increases. Selectivity of TAGs was also slightly influenced by the temperature. Moreover, this chromatographic method is compatible with a mass spectrometer (MS) detector by using atmospheric pressure chemical ionisation (APCI): same fingerprints of cocoa butter and shea butter were obtained with LC-ELSD and LC-APCI-MS. These preliminary results showed that the PGC column could be suitable to separate quickly triacylglycerols in high temperature conditions coupled with ELSD or MS detector.

  11. Quantitation of Free Metanephrines in Plasma by Liquid Chromatography-Tandem Mass Spectrometry.

    PubMed

    Heideloff, Courtney; Payto, Drew; Wang, Sihe

    2016-01-01

    Plasma metanephrines are measured to aid in the diagnosis of pheochromocytomas. In patients with pheochromocytomas there is excessive production of catecholamines and metanephrines. Measurement of plasma free metanephrines is one of the first-line clinical tests that are used for the diagnosis and follow-up of pheochromocytoma. We describe here a liquid chromatography-tandem mass spectrometry method to measure free metanephrines in plasma. Free metanephrine and normetanephrine are extracted via solid-phase extraction. After extraction and evaporation, the reconstituted supernatant is analyzed by high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). The MS/MS is set to selective reaction monitoring mode (180.1 → 148.1 m/z for metanephrine, 183.1 → 168.1 for d3-metanephrine, 166.1 → 134.1 m/z for normetanephrine, and 169.1 → 137.2 m/z for d3-normetanephrine) with positive electrospray ionization. Quantitation is based on peak area ratio of the analyte to its respective deuterated internal standard. The assay is linear from 5.9 to 4090.0 pg/mL for metanephrine and 22.0 to 4386.7 pg/mL for normetanephrine with precision of <6 % over the ranges.

  12. A simple and simultaneous identification method for aloe, catechu and gambir by high performance liquid chromatography.

    PubMed

    Zhao, Yan; Kim, Young Ho; Lee, Wonjae; Lee, Young Keun; Kim, Kyung Tae; Kang, Jong Seong

    2016-01-05

    An effective and rapid method was developed for the simultaneous identification of aloe, catechu and gambir by high performance liquid chromatography-diode array detector (HPLC-DAD). Identification of three maker compounds presented in three medicinal materials was performed on high performance liquid chromatography-mass spectrometry (HPLC-MS). Under the optimal HPLC chromatographic conditions, sixty-two samples were processed on an Optimapak C18 column using a solvent system of acetonitrile (from 10% to 35%) and 0.1% phosphoric acid solution (from 90% to 65%) at a total flow rate of 1.0 mL/min and detected at 270 nm. All calibration curves exhibited good linear relationship (r(2)>0.9992). The relative standard deviation values of intra-day and inter-day precision were less than 1% and 2%, respectively. The recoveries of three analytes ranged from 99.48 to 100.97% with low RSDs (<2%). For the first time, this study demonstrates that the processed aloe, catechu and gambir are sold in local material markets in China and Korea without their correct identification. It indicates the existent of high potential medicinal risk by misuse of three medicinal materials. The developed HPLC method can be applied to prevent unexpected biological activity due to misapplication of medicinal materials.

  13. Exploring the possibilities of cryogenic cooling in liquid chromatography for biological applications: a proof of principle.

    PubMed

    Eghbali, Hamed; Sandra, Koen; Tienpont, Bart; Eeltink, Sebastiaan; Sandra, Pat; Desmet, Gert

    2012-02-21

    The possibilities to use cryogenic cooling to trap components in liquid chromatography was investigated. In a first step, van 't Hoff plots were measured with a reversed-phase column using the temperature control unit of a conventional high performance liquid chromatography (HPLC) system to gain insight in the retention behavior of proteins at low temperatures. It was estimated that retention factors in the range of k = 10(4) could be achieved at T = -20 °C for lysozyme, indicating that temperature is a usable parameter to trap components in LC. In a next step, trapping experiments were carried out on a nano-LC system, equipped with a UV-detector, using a commercial reversed-phase column. An in-house built setup, allowing cooling of a segment of the column down to temperatures below T = -20 °C, was used to trap components. Experiments were conducted under isocratic and gradient conditions with methanol as organic solvent. It is demonstrated that, by thermally trapping and elution of components, an enhanced S/N ratio and decreased peak widths can be obtained. At the same time, a significant increase in pressure drop occurs during the cooling process. Limitations and benefits of the technique are further discussed.

  14. Degradation study of enniatins by liquid chromatography-triple quadrupole linear ion trap mass spectrometry.

    PubMed

    Serrano, A B; Meca, G; Font, G; Ferrer, E

    2013-12-15

    Enniatins A, A1, B and B1 (ENs) are mycotoxins produced by Fusarium spp. and are normal contaminants of cereals and derivate products. In this study, the stability of ENs was evaluated during food processing by simulation of pasta cooking. Thermal treatments at different incubation times (5, 10 and 15 min) and different pH (4, 7 and 10) were applied in an aqueous system and pasta resembling system (PRS). The concentrations of the targeted mycotoxins were determined using liquid chromatography coupled to tandem mass spectrometry. High percentages of ENs reduction (81-100%) were evidenced in the PRS after the treatments at 5, 10 and 15 min of incubation. In contrast to the PRS, an important reduction of the ENs was obtained in the aqueous system after 15 min of incubation (82-100%). In general, no significant differences were observed between acid, neutral and basic solutions. Finally, several ENs degradation products were identified using the technique of liquid chromatography-triple quadrupole linear ion trap mass spectrometry.

  15. Development of Hydrophilic Interaction Liquid Chromatography Method for the Analysis of Moxonidine and Its Impurities

    PubMed Central

    2016-01-01

    Fast and simple hydrophilic interaction liquid chromatography (HILIC) method was developed and validated for the analysis of moxonidine and its four impurities (A, B, C, and D) in pharmaceutical dosage form. All experiments were performed on the Agilent Technologies 1200 high-performance liquid chromatography (HPLC) system using Zorbax RX-SIL, 250 mm × 4.6 mm, 5 μm column as stationary phase (T = 25°C, F = 1 mL/min, and λ = 255 nm), and mixture of acetonitrile and 40 mM ammonium formate buffer (pH 2.8) 80 : 20 (v/v) as mobile phase. Under the optimal chromatographic conditions, selected by central composite design, separation and analysis of moxonidine and its four impurities are enabled within 12 minutes. Validation of the method was conducted in accordance with ICH guidelines. Based on the obtained results selectivity, linearity (r ≥ 0.9976), accuracy (recovery: 93.66%–114.08%), precision (RSD: 0.56%–2.55%), and robustness of the method were confirmed. The obtained values of the limit of detection and quantification revealed that the method can be used for determination of impurities levels below 0.1%. Validated method was applied for determination of moxonidine and its impurities in commercially available tablet formulation. Obtained results confirmed that validated method is fast, simple, and reliable for analysis of moxonidine and its impurities in tablets. PMID:27847672

  16. Isocratic and gradient elution in micellar liquid chromatography with Brij-35.

    PubMed

    Peris-García, Ester; Ortiz-Bolsico, Casandra; Baeza-Baeza, Juan José; García-Alvarez-Coque, María Celia

    2015-06-01

    Polyoxyethylene(23)lauryl ether (known as Brij-35) is a nonionic surfactant, which has been considered as an alternative to the extensively used in micellar liquid chromatography anionic surfactant sodium lauryl (dodecyl) sulfate, for the analysis of drugs and other types of compounds. Brij-35 is the most suitable nonionic surfactant for micellar liquid chromatography, owing to its commercial availability, low cost, low toxicity, high cloud temperature, and low background absorbance. However, it has had minor use. In this work, we gather and discuss some results obtained in our laboratory with several β-blockers, sulfonamides, and flavonoids, concerning the use of Brij-35 as mobile phase modifier in the isocratic and gradient modes. The chromatographic performance for purely micellar eluents (with only surfactant) and hybrid eluents (with surfactant and acetonitrile) is compared. Brij-35 increases the polarity of the alkyl-bonded stationary phase and its polyoxyethylene chain with the hydroxyl end group allows hydrogen-bond interactions, especially for phenolic compounds. This offers the possibility of using aqueous solutions of Brij-35 as mobile phases with sufficiently short retention times. The use of gradients of acetonitrile to keep the concentration of Brij-35 constant is another interesting strategy that yields a significant reduction in the peak widths, which guarantee high resolution.

  17. Applications of thin layer chromatography, high performance liquid chromatography and mass spectrometry in the fermentation and isolation of the antibiotic nybomycin.

    PubMed

    Pope, J A; Nelson, R A; Schaffner, C P; Rosen, R T; Pandey, R C

    1990-09-01

    Thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and mass spectrometry (MS) methods have been developed for the analysis of the antibiotic nybomycin, its derivatives deoxynybomycin and nybomycin acetate, during the fermentation and isolation of nybomycin. Using a quantitative HPLC based assay, the time course of nybomycin production (nybomycin titers) in 1000 liter fermentations was determined. Desorption chemical ionization mass spectrometry (DCI/MS) of standard nybomycin samples, fermentation broth samples and purified fractions suggested the co-production of deoxynybomycin which was not reported previously from this organism. TLC and HPLC were used to confirm the presence of deoxynybomycin in the crude extracts of fermentation broths.

  18. Improving solid oxide fuel cell performance by a single-step co-firing process

    NASA Astrophysics Data System (ADS)

    Dai, Hailu; Chen, Han; He, Shoucheng; Cai, Guifan; Guo, Lucun

    2015-07-01

    Solid oxide fuel cells (SOFCs) with Sm0.2Ce0.8O2-δ (SDC) as the electrolyte are successfully prepared by a single-step co-firing process with the sintering temperature as low as 1100 °C. Different from the conventional SOFC preparation procedure that involves multistep firing processes, the single-step co-firing preparation procedure simplifies the fuel cell preparation procedure and additionally improves the fuel cell performance. The cell prepared by the single-step process exhibits the maximum power density of 289 mW cm-2 at 700 °C, while the cell prepared by the conventional method is only 211 mW cm-2, with an increase of 37% been achieved. The impedance analysis reveals that the single co-firing procedure not only improves the contact between the electrolyte and electrodes, but also lowers the cell polarization resistance, thus leading to a better fuel cell performance.

  19. Use of aluminum phosphate as the dehydration catalyst in single step dimethyl ether process

    DOEpatents

    Peng, Xiang-Dong; Parris, Gene E.; Toseland, Bernard A.; Battavio, Paula J.

    1998-01-01

    The present invention pertains to a process for the coproduction of methanol and dimethyl ether (DME) directly from a synthesis gas in a single step (hereafter, the "single step DME process"). In this process, the synthesis gas comprising hydrogen and carbon oxides is contacted with a dual catalyst system comprising a physical mixture of a methanol synthesis catalyst and a methanol dehydration catalyst. The present invention is an improvement to this process for providing an active and stable catalyst system. The improvement comprises the use of an aluminum phosphate based catalyst as the methanol dehydration catalyst. Due to its moderate acidity, such a catalyst avoids the coke formation and catalyst interaction problems associated with the conventional dual catalyst systems taught for the single step DME process.

  20. Characterization of hydroxypropylmethylcellulose (HPMC) using comprehensive two-dimensional liquid chromatography.

    PubMed

    Greiderer, Andreas; Steeneken, Linda; Aalbers, Tom; Vivó-Truyols, Gabriel; Schoenmakers, Peter

    2011-08-26

    Various hydroxyl-propylmethylcellulose (HPMC) polymers were characterized according to size and compositional distributions (percentage of methoxyl and hydroxyl-propoxyl substitution) by means of comprehensive two-dimensional liquid chromatography (LC×LC) using reversed-phase (RP) liquid chromatography in the first dimension and aqueous size-exclusion chromatography (aq-SEC) in the second dimension. RP separation was carried out in gradient-elution mode applying 0.05% TFA in water and 1-propanol, while 0.05% TFA in water was used as mobile phase in aqueous SEC. A two-position ten-port switching valve equipped with two storage loops was used to realize LC×LC. Detection of HPMC was accomplished by charged-aerosol detection (CAD). Data processing to visualize chromatograms was carried out using Matlab software. The significant influence of the LC×LC temperature on (the retention of) HPMC was studied using a column oven which allowed accurate temperature control. Due to the phenomenon of thermal gelation, which is a result of methyl and hydroxypropyl substitution of anhydroglucose units from the cellulose backbone, we were able to obtain additional, specific information on compositional characteristics of various HPMC samples. As the retention behaviour of gelated and non-gelated polymer proved to be different, the fraction of the polymer that is gelated in the chromatographic column could be monitored at different temperatures. Moreover, the temperature at which half of the polymer is gelated could be correlated with the cloud-point temperature. As a result, differences in inherent cloud points of modified cellulose can be used as a further distinguishing property in "temperature-responsive" LC×LC.

  1. Determination of Catechol Estrogen Adducts by High-Performance Liquid Chromatography: Establishing Biomarkers for the Early Detection of Breast Cancer

    DTIC Science & Technology

    1999-07-01

    Catechol Estrogen Adducts by High- Performance Liquid Chromatography: Establishing Biomarkers for the Early Detection of Breast Cancer PRINCIPAL...DAMD17-98-1-8216 Chromatography: Establishing Biomarkers for the Early Detection of Breast Cancer 6. AUTHOR(S) Douglas E. Stack, Ph.D. 7. PERFORMING...ultimate goal of this research is the development of a biomarker for the early detection of breast cancer. 14. SUBJECT TERMS 15. NUMBER OF PAGES Breast

  2. 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)

  3. Ultrasound-assisted ionic liquid/ionic liquid-dispersive liquid-liquid microextraction for the determination of sulfonamides in infant formula milk powder using high-performance liquid chromatography.

    PubMed

    Gao, Shiqian; Yang, Xiao; Yu, Wei; Liu, Zhongling; Zhang, Hanqi

    2012-09-15

    Ultrasound-assisted ionic liquid/ionic liquid-dispersive liquid-liquid microextraction (UA-IL/IL-DLLME) high-performance liquid chromatography was developed and applied to the extraction, separation and determination of sulfonamides in infant formula milk powder samples. The hydrophobic IL and hydrophilic IL were used as extraction solvent and dispersion solvent, respectively. The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of [C(6)MIM][PF(6)] dispersed entirely into sample solution with help of [C(4)MIM][BF(4)]. The purification of sample and concentration of target analytes were performed simultaneously. The introduction of ion-pairing agent (NH(4)PF(6)) was beneficial to the improvement of recoveries for IL phase and analytes. The experimental parameters of the UA-IL/IL-DLLME, including concentration of [C(6)MIM][PF(6)] and [C(4)MIM][BF(4)] in sample solution, ultrasound extraction time, pH value of sample solution and amount of ion-pairing agent (NH(4)PF(6)), were evaluated. The limits of detection for sulfamerazine, sulfamethizole, sulfachlorpyridazine, sulfamonomethoxine, sulfmethoxazole and sulfisoxazole were 2.94, 9.26, 16.7, 5.28, 3.35 and 6.66 μg kg(-1), respectively. When the present method was applied to the analysis of infant formula milk powder samples, the recoveries of the analytes ranged from 90.4% to 114.8% and relative standard deviations were lower than 7.5%. The proposed method was compared with the ionic liquid-homogeneous liquid-liquid microextraction, ionic liquid-ultrasound-assisted emulsification-microextraction and ionic liquid-temperature-controlled-DLLME. The results indicated that the proposed method is effective for the extraction of the sulfonamides in milk powder samples.

  4. EPA Method 8321B (SW-846): Solvent-Extractable Nonvolatile Compounds by High Performance Liquid Chromatography-Thermospray-Mass Spectrometry (HPLC-TS-MS) or Ultraviolet (UV) Detection

    EPA Pesticide Factsheets

    Method 8321B describes procedures for preparation and analysis of solid, aqueous liquid, drinking water and wipe samples using high performance liquid chromatography and mass spectrometry for extractable non-volatile compounds.

  5. Determination of rare earth elements in high purity rare earth oxides by liquid chromatography, thermionic mass spectrometry and combined liquid chromatography/thermionic mass spectrometry

    NASA Astrophysics Data System (ADS)

    Stijfhoorn, D. E.; Stray, H.; Hjelmseth, H.

    1993-03-01

    A high-performance liquid Chromatographie (HPLC) method for the determination of rare earth elements in rocks has been modified and used for the determination of rare earth elements (REE) in high purity rare earth oxides. The detection limit was 1-1.5 ng or 2-3 mg/kg when a solution corresponding to 0.5 mg of the rare earth oxide was injected. The REE determination was also carried out by adding a mixture of selected REE isotopes to the sample and analysing the collected HPLC-fractions by mass spectrometry (MS) using a thermionic source. Since the matrix element was not collected, interference from this element during the mass spectrometric analysis was avoided. Detection limits as low as 0.5 mg/kg could then be obtained. Detection limits as low as 0.05 mg/kg were possible by MS without HPLC-pre-separation, but this approach could only be used for those elements that were not affected by the matrix. Commercial samples of high purity Nd 2O 3, Gd 2O 3 and Dy 2O 3 were analysed in this study, and a comparison of results obtained by HPLC, combined HPLC/MS and direct MS are presented.

  6. Separation and characterisation of beta2-microglobulin folding conformers by ion-exchange liquid chromatography and ion-exchange liquid chromatography-mass spectrometry.

    PubMed

    Bertoletti, Laura; Regazzoni, Luca; Aldini, Giancarlo; Colombo, Raffaella; Abballe, Franco; Caccialanza, Gabriele; De Lorenzi, Ersilia

    2013-04-10

    In this work we present for the first time the use of ion-exchange liquid chromatography to separate the native form and a partially structured intermediate of the folding of the amyloidogenic protein beta2-microglobulin. Using a strong anion-exchange column that accounts for the differences in charge exposure of the two conformers, a LC-UV method is initially optimised in terms of mobile phase pH, composition and temperature. The preferred mobile phase conditions that afford useful information were found to be 35 mM ammonium formate, pH 7.4 at 25°C. The dynamic equilibrium of the two species is demonstrated upon increasing the concentration of acetonitrile in the protein sample. Then, the chromatographic method is transferred to MS detection and the respective charge state distributions of the separated conformers are identified. The LC-MS results demonstrate that one of the conformers is partially unfolded, compared with the native and more compact species. The correspondence with previous results obtained in free solution by capillary electrophoresis suggest that strong ion exchange LC-MS does not alter beta2-microglobulin conformation and maintains the dynamic equilibrium already observed between the native protein and its folding intermediate.

  7. Application of polymer based stationary phases in high performance liquid chromatography and capillary high performance liquid chromatography hyphenated to microcoil 1H nuclear magnetic resonance spectroscopy.

    PubMed

    Grynbaum, Marc David; Meyer, Christoph; Putzbach, Karsten; Rehbein, Jens; Albert, Klaus

    2007-07-13

    The increased demand for chromatographic materials that are able to achieve a fast separation of large quantities of structure analogues is a great challenge. It is known that polymer based chromatographic materials have a higher loadability, compared to silica based sorbents. Unfortunately these polymer materials cannot be used under high pressure which is necessary in order to obtain high flow rates, and hence long times are needed to perform a separation. However, by immobilizing a polymer on a mechanically stable porous silica core, this problem can be circumvented and higher flows become feasible on these materials. Especially for capillary liquid chromatography hyphenated with nuclear magnetic resonance a high loadability is of great importance in order to obtain sharp, resolved, and concentrated peaks thus resulting in a good signal to noise ratio in the NMR experiment. Therefore, a highly shape selective chromatographic sorbent was developed by covalently immobilizing a poly(ethylene-co-acrylic) acid copolymer (-CH(2)CH(2)-)(x)[CH(2)CH(CO(2)H)-](y) (x=119, y=2.4) with a mass fraction of acrylic acid of 5% as stationary phase on silica via a spacer molecule (3-glycidoxypropyltrimethoxysilane). First, the loadability of this sorbent compared to C(30) is demonstrated by the HPLC separation of two xanthophyll isomers. Subsequently, it has been successfully employed in the hyphenation of capillary HPLC with microcoil (1)H NMR spectroscopy by separating and identifying a highly concentrated solution of the tocopherol homologues.

  8. Utility of liquid chromatography/fast atom bombardment mass spectrometry and liquid chromatography/thermospray mass spectrometry for structure identification of metabolites of a fluorinated herbicide.

    PubMed

    Fujiwara, H; Chott, R C; Solsten, R T

    1992-09-01

    This study demonstrates a useful application of on-line microbore high-performance liquid chromatography (HPLC) fast atom bombardment (FAB) and thermospray (TSP) mass spectrometry techniques for identification of metabolites from the in vitro metabolism of an experimental Monsanto herbicide: 2-chloro-N-(ethoxymethyl-N-[2-methyl-6- (trifluoromethyl)phenyl]acetamide, 'chloroacetanilide'. The microbore HPLC FAB technique on a high-resolution sector mass spectrometer accelerated identification of polar metabolites from the in vitro metabolism study of the herbicide. It provided good chromatographic resolution and excellent FAB sensitivity with strong protonated molecular ions. Scanning high-resolution LC/FAB mass spectrometry also provided molecular formulae for structural elucidation of unknown metabolites. Sample purification and concentration were minimized. Identification of less polar metabolites was carried out using LC/TSP mass spectrometry with a quadrupole mass spectrometer. LC/TSP mass spectrometry provided useful structural information for both polar and less polar metabolites because their spectra showed more fragmentation than FAB spectra. Glutathione conjugation was the major reaction observed during in vitro incubation of the herbicide. Oxidation of the chloroacetanilide by rat liver enzymes was also a significant metabolic reaction. Seven metabolites were identified, of which four were glutathione conjugates.

  9. 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.

  10. [Construction of a two-dimensional liquid chromatography separation system for high abundance proteins depletion in human plasma].

    PubMed

    Zhu, Shaochun; Zhang, Xueyang; Gao, Mingxia; Yan, Guoquan; Zhang, Xiangmin

    2011-09-01

    High abundance proteins existing in human plasma severely impede the detection of low abundance proteins. This is one of the most difficult problems encountered in plasma proteomics research. We developed a two-dimensional liquid chromatography system with strong anion exchange chromatography-reversed-phase liquid chromatography (SAX-RPLC) for the extensive separation of plasma proteins and selective depletion of high abundance proteins. TSKgel SuperQ-5PW was selected as the first dimensional separation column for crude human plasma fractionation and Jupiter C4 column was selected as the second dimensional separation column. Separation gradients of the two-dimensional liquid chromatography system were optimized to ensure an extensive separation of plasma proteins. Ten peaks with high signal intensities ( >20 mAU) at 215 nm during the second dimensional separation were collected and identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). As a result, 32 proteins, all of which were reported to be high abundance proteins in plasma, including human serum albumin (HSA), immunoglobulin G (IgG) and so on were successfully identified. This system provides an effective method for future depletion of more high abundance proteins and in-depth research in human plasma proteomics.

  11. Quantitative determination of methamphetamine in oral fluid by liquid-liquid extraction and gas chromatography/mass spectrometry.

    PubMed

    Bahmanabadi, L; Akhgari, M; Jokar, F; Sadeghi, H B

    2017-02-01

    Methamphetamine abuse is one of the most medical and social problems many countries face. In spite of the ban on the use of methamphetamine, it is widely available in Iran's drug black market. There are many analytical methods for the detection of methamphetamine in biological specimen. Oral fluid has become a popular specimen to test for the presence of methamphetamine. The purpose of the present study was to develop a method for the extraction and detection of methamphetamine in oral fluid samples using liquid-liquid extraction (LLE) and gas chromatography/mass spectrometry (GC/MS) methods. An analytical study was designed in that blank and 50 authentic oral fluid samples were collected to be first extracted by LLE and subsequently analysed by GC/MS. The method was fully validated and showed an excellent intra- and inter-assay precision (reflex sympathetic dystrophy ˂ 10%) for external quality control samples. Recovery with LLE methods was 96%. Limit of detection and limit of quantitation were 5 and 15 ng/mL, respectively. The method showed high selectivity, no additional peak due to interfering substances in samples was observed. The introduced method was sensitive, accurate and precise enough for the extraction of methamphetamine from oral fluid samples in forensic toxicology laboratories.

  12. Determination of macrolide antibiotics in meat and fish using pressurized liquid extraction and liquid chromatography-mass spectrometry.

    PubMed

    Berrada, Houda; Borrull, Francesc; Font, Guillermina; Marcé, Rosa Maria

    2008-10-24

    We developed a method for determining the quantities of seven macrolide antibiotics in meat and fish by using pressurized liquid extraction (PLE) and liquid chromatography-mass spectrometry with electrospray ionization (LC-(ESI)MS). The PLE was optimized with regard to solvents, temperature, pressure, extraction time and number of cycles. The optimum conditions were: methanol as the extraction solvent; a temperature of 80 degrees C; a pressure of 1500psi; an extraction time of 15min; 2 cycles; a flush volume of 150% and a purge time of 300s. All recoveries for macrolide antibiotics were over 77% at 200mug/kg, except for erythromycin, which was 58%. The repeatability and reproducibility on days in between, expressed as %RSD (n=12), were lower than 10% and 12%, respectively. The quantification limits of all compounds were 25mug/kg of dry weight of animal muscle except for troleandomycin (50mug/kg). The method was applied to determine the pharmaceuticals in real samples taken from 18 meat and fish samples. The results showed that PLE is quantitative short time consuming technique, with use of smaller initial sample sizes. Greater specificity and selectivity in extraction and increased potential for automation were shown.

  13. Determination of Levetiracetam in Human Plasma by Dispersive Liquid-Liquid Microextraction Followed by Gas Chromatography-Mass Spectrometry

    PubMed Central

    2016-01-01

    Levetiracetam (LEV) is an antiepileptic drug that is clinically effective in generalized and partial epilepsy syndromes. The use of this drug has been increasing in clinical practice and intra- or -interindividual variability has been exhibited for special population. For this reason, bioanalytical methods are required for drug monitoring in biological matrices. So this work presents a dispersive liquid-liquid microextraction method followed by gas chromatography-mass spectrometry (DLLME-GC-MS) for LEV quantification in human plasma. However, due to the matrix complexity a previous purification step is required. Unlike other pretreatment techniques presented in the literature, for the first time, a procedure employing ultrafiltration tubes Amicon® (10 kDa porous size) without organic solvent consumption was developed. GC-MS analyses were carried out using a linear temperature program, capillary fused silica column, and helium as the carrier gas. DLLME optimized parameters were type and volume of extraction and dispersing solvents, salt addition, and vortex agitation time. Under chosen parameters (extraction solvent: chloroform, 130 μL; dispersing solvent: isopropyl alcohol, 400 μL; no salt addition and no vortex agitation time), the method was completely validated and all parameters were in agreement with the literature recommendations. LEV was quantified in patient's plasma sample using less than 550 μL of organic solvent. PMID:27830105

  14. Analysis of oestrogenic compounds in dairy products by hollow-fibre liquid-phase microextraction coupled to liquid chromatography.

    PubMed

    Socas-Rodríguez, Bárbara; Asensio-Ramos, María; Hernández-Borges, Javier; Rodríguez-Delgado, Miguel Ángel

    2014-04-15

    In this work, the potential of a hollow-fibre liquid-phase microextraction (LPME)-based method has been studied and validated for the extraction of a group of nine oestrogenic compounds four of them being natural (oestriol, 17β-oestradiol, 17α-oestradiol and oestrone), four being synthetic (17α-ethynyloestradiol, diethylstilbestrol, dienestrol and hexestrol) and one metabolite (2-hydroxyoestradiol) in different dairy products (whole and skimmed natural yogurt, a probiotic yogurt-type drink and cheese). The methodology includes a prior protein precipitation with acidified acetonitrile for all samples and an additional defatting step with n-hexane for cheese, the matrix with the highest fat content. Later separation, determination and quantification were done by high-performance liquid chromatography coupled to a diode array detector and a fluorescence detector set in series. Calibration, sensitivity, precision and accuracy of the method were carried out in the selected matrices, providing good linearity, LODs in the low μg/kg or μg/L range, good precision and appropriate accuracy.

  15. High-performance liquid chromatography using pressurized liquid extraction for the determination of seven tetracyclines in egg, fish and shrimp.

    PubMed

    Liu, Yu; Yang, Hailan; Yang, Sheng; Hu, Qiwei; Cheng, Hongbo; Liu, Huiyu; Qiu, Yinsheng

    2013-02-15

    A simple and especially rapid method, pressurized liquid extraction, has been developed and applied to the quantitative determination of oxytetracycline, tetracycline, chlortetracycline, minocycline, methacycline, demeclocycline and doxycycline in egg, fish and shrimp. The procedure consisted of a trichloracetic acid/methanol extraction conducted at elevated temperature (60°C) and pressure (65bar), without further clean-up, the extraction solution was concentrated and finally for high-performance liquid chromatography analysis. The limits of detection were 5.0-10.0μg/kg and the limits of quantification were 10.0-15.0μg/kg for tetracyclines in egg, fish and shrimp using UV detection. The analytical limits CCα and CCβ were also calculated. The recoveries of tetracyclines spiked at levels of 15-300μg/kg, averaged 75.6-103.5% with the relative standard deviation values less than 11%. The optimized procedure has been successfully applied to real samples in our laboratories. It demonstrated that the new method was robust and useful for monitoring and quantification of 7 tetracycline residues in food of animal origin.

  16. Determination of priority phenolic pollutants exploiting an in-syringe dispersive liquid-liquid microextraction-multisyringe chromatography system.

    PubMed

    González, Alba; Avivar, Jessica; Cerdà, Víctor

    2015-03-01

    An automatic phenolic compounds analyzer is presented. The system performs online magnetic-stirring-assisted dispersive liquid-liquid microextraction before multisyringe chromatography (MSC) using a monolithic Chromolith Flash RP-18e column. The extraction behavior of the following phenolic pollutants: phenol, 2-nitrophenol, 4-nitrophenol, 2-chlorophenol, 2,4-diclorophenol, and 2,4,6-trichlorophenol, has been studied. A critical comparison of extractants (tributyl phosphate, acetonitrile, hexane, and 1-chlorobutane) and disperser solvents (acetone, acetonitrile, ethanol, methanol, 1-propanol, and 2-propanol) was made. Tributyl phosphate and acetonitrile were chosen as the extractant and the disperser solvent, respectively, since these showed the best performance. Phenols were online back-extracted into NaOH and neutralized before multi-isocratic chromatographic separation. The proposed analyzer can be applied for wide linear working ranges, i.e., between 40 and 20,000 μg L(-1). The precision of the developed system has been proved, with maximum values for the intraday and interday precision of 4.4 % and 5.2 %, respectively, expressed as relative standard deviation, and high preconcentration factors (9.3-10.5) for most of the compounds studied. The method developed was successfully applied to natural water samples.

  17. Determination of artificial sweeteners in sewage sludge samples using pressurised liquid extraction and liquid chromatography-tandem mass spectrometry.

    PubMed

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

    2013-12-13

    An analytical method for the determination of six artificial sweeteners in sewage sludge has been developed. The procedure is based on pressurised liquid extraction (PLE) with water followed by solid-phase extraction (SPE) and subsequent liquid chromatography-tandem mass spectrometry analysis. After optimisation of the different PLE parameters, extraction with aqueous 500mM formate buffer (pH 3.5) at 80°C during a single static cycle of 21min proved to be best conditions. After a subsequent SPE, quantification limits, referred to dry weight (dw) of sewage sludge, ranged from 0.3ng/g for acesulfame (ACE) to 16ng/g for saccharin (SAC) and neohespiridine dihydrochalcone. The trueness, expressed as recovery, ranged between 72% and 105% and the precision, expressed as relative standard deviation, was lower than 16%. Moreover, the method proved its linearity up to the 2μg/g range. Finally, the described method was applied to the determination of the artificial sweeteners in primary and secondary sewage sludge from urban wastewater treatment plants. Four of the six studied artificial sweeteners (ACE, cyclamate, SAC and sucralose) were found in the samples at concentrations ranging from 17 to 628ng/g dw.

  18. Fast screening of perfluorooctane sulfonate in water using vortex-assisted liquid-liquid microextraction coupled to liquid chromatography-mass spectrometry.

    PubMed

    Papadopoulou, Aikaterini; Román, Iván P; Canals, Antonio; Tyrovola, Konstantina; Psillakis, Elefteria

    2011-04-08

    Fast screening of trace amounts of the perfluorooctane sulfonate anion (PFOS) in water samples was performed following a simple, fast and efficient sample preparation procedure based on vortex-assisted liquid-liquid microextraction (VALLME) prior to liquid chromatography-mass spectrometry. VALLME initially uses vortex agitation, a mild emulsification procedure to disperse microvolumes of octanol, a low density extractant solvent, in the aqueous sample. Microextraction under equilibrium conditions is thus achieved within few minutes. Subsequently, centrifugation separates the two phases and restores the initial microdrop shape of the octanol acceptor phase, which can be collected and used for liquid chromatography-single quadrupole mass spectrometry analysis. Several experimental parameters were controlled and the optimum conditions found were: 50 μL of octanol as the extractant phase; 20 mL aqueous donor samples (pH=2); a 2 min vortex extraction time with the vortex agitator set at a 2500 rpm rotational speed; no ionic strength adjustment. Centrifugation for 2 min at 3500 rpm yielded separation of the two phases throughout this study. Enhanced extraction efficiencies were observed at low pH which was likely due to enhanced electrostatic interaction between the negatively PFOS molecules and the positively charged octanol/water interface. The effect of pH was reduced in the presence of sodium chloride, likely due to electrical double layer compression. The linear response range for PFOS was from 5 to 500 ng L(-1) (coefficient of determination, r(2), 0.997) and the relative standard deviation for aqueous solutions containing 10 and 500 ng L(-1) PFOS were 7.4% and 6.5%, respectively. The limit of detection was 1.6 ng L(-1) with an enrichment factor of approximately 250. Analysis of spiked tap, river and well water samples revealed that matrix did not affect extraction.

  19. Single-Step Synthesis of Cubic Y2O3:Eu3+ Nanophosphor by Flame Spray Pyrolysis

    NASA Astrophysics Data System (ADS)

    Lee, Jae Seok; Lee, Jinhyung; Han, Hyuksu; Kumar, Purushottam; Singh, Rajiv K.

    2016-12-01

    In this report, we investigated a single-step process for formation of high crystallinity Y2O3:Eu3+ red nanophosphor by flame spray pyrolysis (FSP) without post-heat treatments. Crystallinity of as-formed nanophosphor particle was improved by addition of urea to the nitrate-based liquid precursor. Urea increased the temperature in the flame zone thus ensuring Y2O3:Eu3+ formation at higher flame temperature. Higher temperature reached during combustion of urea promoted the formation of better crystallinity, nano-sized and spherical-shaped particles. The effect of urea in the precursor to obtain high-efficiency Y2O3:Eu3+ nanophosphor was studied.

  20. Identification of synthetic by-products in combinatorial libraries using high performance liquid chromatography-electrospray ionization mass spectrometry.

    PubMed

    Aubagnac, J L; Amblard, M; Enjalbal, C; Subra, G; Martinez, J; Durand, P; Renaut, P

    1999-10-01

    High performance liquid chromatography (HPLC), electrospray ionization mass spectrometry (ESI) and high performance liquid chromatography coupled to mass spectrometry (LC-MS) were used to analyze randomly chosen samples from parallel syntheses carried out on derivatized polypropylene crowns compatible with a Multipin solid support system. Side-reactions and by-products were clearly identified, and the yields of the expected molecules were unexpectedly low for most samples. LC-MS was superior to HPLC with absorbance detection or electrospray mass spectrometry alone for determining the identity and purity of each desired combinatorial compounds.

  1. Determination of chlorophenols in honey samples using in-situ ionic liquid-dispersive liquid-liquid microextraction as a pretreatment method followed by high-performance liquid chromatography.

    PubMed

    Fan, Chen; Li, Nai; Cao, Xueli

    2015-05-01

    In-situ ionic liquid-dispersive liquid-liquid microextraction (IL-DLLME) method was developed as a pretreatment method for the detection of six chlorophenols (CPs) in honey samples. The hydrophobic ionic liquid [C4MIM][NTf2], formed in-situ by the hydrophilic ionic liquid [C4MIM][BF4] and the ion exchange reagent LiNTf2 was used as the microextractant solvent of CPs from honey sample. Then the enriched analytes were back-extracted into 40 μL of 0.14 M NaOH solution and finally subjected to analysis by high-performance liquid chromatography. The method showed low limit of detection of CPs, 0.8-3.2 μg/L and high enrichment factor, 34-65 with the recoveries range from 91.60% to 114.33%. The method is simple, rapid, environmentally friendly and with high extraction efficiency.

  2. Mixed-mode chromatography integrated with high-performance liquid chromatography for protein analysis and separation: Using bovine serum albumin and lysozyme as the model target.

    PubMed

    Xia, Hai-Feng; Don, Bin-Bin; Zheng, Meng-Jie

    2016-05-01

    A type of mixed-mode chromatography was integrated with high-performance liquid chromatography for protein analysis and separation. The chromatographic behavior was tested using bovine serum albumin and lysozyme as model proteins. For the mixed-mode column, the silica beads were activated with γ-(2,3-epoxypropoxy)-propytrimethoxysilane and coupled with 4-mercaptopyridine as the functional ligand. The effects of pH, salt, and the organic solvent conditions of the mobile phase on the retention behavior were studied, which provided valuable clues for separation strategy. When eluted with a suitable pH gradient, salt concentration gradient, and acetonitrile content gradient, the separation behavior of bovine serum albumin and lysozyme could be controlled by altering the conditions of the mobile phase. The results indicated this type of chromatography might be a useful method for protein analysis and separation.

  3. 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.

  4. Trace analysis of herbicides in wastewaters by a dispersive liquid-liquid microextraction approach and liquid chromatography with quadrupole linear ion trap mass spectrometry: evaluation of green parameters.

    PubMed

    del Mar Parrilla Vázquez, Maria; Martínez Galera, Maria; Parrilla Vázquez, Piedad; Uclés Moreno, Ana

    2014-06-01

    An analytical method for determining phenylureas (monuron, isoproturon, diuron, linuron and neburon) and propanil herbicides in wastewater has been developed and validated, and the most significant parameters were compared with the corresponding ones found in the literature, thus showing the method performance. The method involves pre-concentration by a simple, rapid, sensitive and low environmental toxicity temperature-controlled ionic liquid dispersive liquid-liquid microextraction procedure. The herbicides were identified and determined by liquid chromatography with a hybrid triple quadrupole linear ion trap mass spectrometer. Data acquisition in selected-reaction monitoring mode allowed the simultaneous identification and quantification of the analytes using two transitions. The information dependent acquisition scan was performed to carry out the identification of those analytes whose second transition was present at low intensity, also providing extra confirmation for the other analytes. Limits of quantification were in the range 1.0-5.0 ng/L. Good recoveries (95-103%) were obtained for the extraction of the target analytes in wastewater samples. The methodology developed was applied to analyze effluent wastewater samples from a wastewater treatment plant located in an agricultural zone of Almería (Spain) and the results indicated the presence of diuron at mean concentration levels of 73.5 ng/L.

  5. Dispersive liquid-liquid microextraction for the determination of new generation pesticides in soils by liquid chromatography and tandem mass spectrometry.

    PubMed

    Pastor-Belda, Marta; Garrido, Isabel; Campillo, Natalia; Viñas, Pilar; Hellín, Pilar; Flores, Pilar; Fenoll, José

    2015-05-15

    A sensitive method for the determination of five new generation pesticides (chlorantraniliprole, spirotetramat, spiromesifen, spirodiclofen and flubendiamide) in soil samples has been developed using liquid chromatography and tandem mass spectrometry (LC-MS(2)) with a triple-quadrupole in the multiple reaction monitoring mode. The target analytes are released from the solid matrix by single-phase extraction in acetonitrile (SLE), this organic phase being used as dispersant solvent in the dispersive liquid-liquid microextraction (DLLME) step. The different parameters affecting the extraction efficiency in DLLME were carefully studied, being 1.5mL of acetonitrile extract (disperser solvent), 125μL carbon tetrachloride (extraction solvent) and 10mL aqueous solution, the selected conditions. The enriched organic phase was evaporated, reconstituted with 50μL acetonitrile and injected into a liquid chromatograph with a mobile phase composed of acetonitrile and 0.1% (v/v) formic acid under gradient elution and a C8 stationary phase. Detection limits in the 0.0015-0.0090ngg(-1) range were obtained. Insecticide concentrations ranging from 0.03 to 197ngg(-1), depending on the compound, were found in the soil samples analysed. The recovery values obtained by SLE-DLLME-LC-ESI-MS(2) for three spiked soils at three concentration levels varied between 87 and 114%, with RSDs of between 5.5 and 14%.

  6. A dispersive liquid-liquid micellar microextraction for the determination of pharmaceutical compounds in wastewaters using ultra-high-performace liquid chromatography with DAD detection.

    PubMed

    Montesdeoca-Esponda, Sarah; Mahugo-Santana, Cristina; Sosa-Ferrera, Zoraida; Santana-Rodríguez, José Juan

    2015-03-01

    A dispersive liquid-liquid micellar microextraction (DLLMME) method coupled with ultra-high-performance liquid chromatography (UHPLC) using Diode Array Detector (DAD) detector was developed for the analysis of five pharmaceutical compounds of different nature in wastewaters. A micellar solution of a surfactant, polidocanol, as extraction solvent (100 μL) and chloroform as dispersive solvent (200 μL) were used to extract and preconcentrate the target analytes. Samples were heated above critical temperature and the cloudy solution was centrifuged. After removing the chloroform, the reduced volume of surfactant was then injected in the UHPLC system. In order to obtain high extraction efficiency, the parameters affecting the liquid-phase microextraction, such as time and temperature extraction, ionic strength and surfactant and organic solvent volume, were optimized using an experimental design. Under the optimized conditions, this procedure allows enrichment factors of up to 47-fold. The detection limit of the method ranged from 0.1 to 2.0 µg/L for the different pharmaceuticals. Relative standard deviations were <26% for all compounds. The procedure was applied to samples from final effluent collected from wastewater treatment plants in Las Palmas de Gran Canaria (Spain), and two compounds were measured at 67 and 113 µg/L in one of them.

  7. Ultra-high-pressure liquid chromatography-tandem mass spectrometry method for the determination of alkylphenols in soil.

    PubMed

    Wang, Jing; Pan, Hefang; Liu, Zhengzheng; Ge, Fei

    2009-03-20

    A novel method has been developed for the determination of alkylphenols in soil by ultra-high-pressure liquid chromatography employing small particle sizes, combined with tandem mass spectrometry. Soil samples were extracted with pressurized liquid extraction (PLE) and then cleaned with solid-phase extraction (SPE). The extracts were separated on C18 column (1.7 microm, 50 mm x 2.1mm) with a gradient elution and a mobile phase consisting of water and acetonitrile, and then detected by an electrospray ionization tandem mass spectrometry in negative ion mode with multiple reaction monitoring (MRM). Compared with traditional liquid chromatography, it took ultra-high-pressure liquid chromatography much less time to analyze alkylphenols. Additionally, the ultra-high-pressure liquid chromatography/tandem mass spectrometry method produces satisfactory reliability, sensitivity, and accuracy. The average recoveries of the three target analytes were 74.0-103.4%, with the RSD<15%. The calibration curves for alkylphenols were linear within the range of 0.01-0.4 microg/ml, with the correlation coefficients greater than 0.99. When 10 g soil sample was used for analysis, the limits of quantification (LOQs) of the three alkylphenols were all 1.0 microg/kg.

  8. Simultaneous determination of drugs in human autopsy material using phase-optimized liquid chromatography.

    PubMed

    Oertel, R; Pietsch, J; Arenz, N; Zeitz, S G; Goltz, L; Kirch, W

    2012-12-01

    In legal medicine in many cases drugs are detected in autopsy material without connection to the cause of death, and until now no further investigations have taken place. In our study more than 50 drugs were measured directly in several compartments. The deceased had received continual therapeutic treatment, treatment during an operation or an unsuccessful emergency therapy. Liquid-liquid extraction and an LC-MS/MS method were developed for the determination of these drug concentrations. When measuring many transitions in a biological matrix, two problems should be excluded: ion suppression and too few measurement points per peak. A relatively short operation time and sufficient separation were achieved by column, eluent and gradient optimization with POPLC (phase-optimized liquid chromatography). Various autopsy materials from about 170 cases were investigated. In particular, in nine cases with four or more simultaneously determined drugs, their distribution in the compartments is very interesting for pharmacokinetic examinations. The distribution patterns of the drugs in the compartments of one individual deceased were compared. This meant that the great differences between subjects that are normally encountered these studies could be excluded. Measurements of drug concentrations in human autopsy material deepens knowledge of the respective drugs' pharmacokinetics.

  9. Determination of ethyl glucuronide in human hair by hydrophilic interaction liquid chromatography-tandem mass spectrometry.

    PubMed

    Yaldiz, Fadile; Daglioglu, Nebile; Hilal, Ahmet; Keten, Alper; Gülmen, Mete Korkut

    2013-10-01

    Ethyl glucuronide (EtG) is a direct metabolite of ethanol and has been utilized as a marker for alcohol intake. This study presents development, validation and application of a new hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) method for the analysis of EtG in human hair samples. The linearity was assessed in the range of 5-2000 pg/mg hair, with a correlation coefficient of >0.99. The method was selective and sensitive, with a limit of detection (LOD) and limit of quantitation (LOQ) of 0.05 pg/mg and 0.18 pg/mg in hair, respectively. Differently from the extraction procedures in the literature, a fast and simple liquid-liquid method was used and highest recoveries and cleanest extracts were obtained. The method was successfully applied to 30 human hair samples which were taken from those who state they consume alcohol. EtG concentrations in the hair samples of alcohol users participated in this study, ranged between 1.34 and 82.73 pg/mg. From the concentration of EtG in hair strands 20 of the 30 subjects can be considered regular moderate drinkers.

  10. Comprehensive characterization of rodenticides in wastewater by liquid chromatography-tandem mass spectrometry.

    PubMed

    Gómez-Canela, Cristian; Vázquez-Chica, Alberto; Lacorte, Silvia

    2014-01-01

    Rodenticides are used as pest control to eradicate rodents and have emerged as new environmental contaminants due to their widespread use in domestic and urban infrastructures. In this study, we have developed and validated an analytical methodology based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of 13 anticoagulant rodenticides in wastewater. In a first step, ionization conditions were tested in electrospray mode, and positive ionization gave the highest sensitivity. Fragmentation patterns were determined and two selected reaction monitoring (SRM) transitions were selected for each compound. Using a Zorbax Eclipse XDB-C18 column and specific SRM transitions, 13 compounds were resolved. The LC-MS/MS method provided good linearity, sensitivity, intra- and inter-day precision, and good identification capabilities for these compounds in wastewaters. Thereafter miniaturized liquid-liquid extraction (LLE) and solid-phase extraction (SPE) were optimized. Oasis HLB and Strata WA SPE cartridges with methanol/dichloromethane as eluting solvents provided good recoveries and limits of detection ranged between 0.34 and 20 ng L(-1), whereas LLE failed to recover some compounds. Finally, the performance of both LLE and SPE methods was evaluated by analyzing rodenticides in a set of wastewaters. Warfarin was the only detected compound at nanogram per liter level, and good agreement was observed between LLE and SPE.

  11. Analysis of amphetamines and metabolites in urine with ultra performance liquid chromatography tandem mass spectrometry.

    PubMed

    Ramírez Fernández, María del Mar; Wille, Sarah M R; di Fazio, Vincent; Gosselin, Matthias; Samyn, Nele

    2010-06-01

    A simple, rapid and sensitive ultra performance liquid chromatography tandem mass spectrometry method was developed and fully validated for the quantitative determination of seven amphetamines and metabolites in urine. The method was validated for selectivity, linearity, LOQ, LOD, imprecision, bias, analyte and processed sample stability, matrix effect, recovery, carryover and dilution integrity. A classic liquid-liquid extraction with ethyl acetate was used as sample preparation procedure. The compounds were separated on an Acquity UPLC HSS C18 column in 6.8 min. The linear dynamic range was established from 25 to 500 ng/mL. The limit of quantification was fixed to the lowest calibrator level and the limit of detection ranged from 0.125 to 2.5 ng/mL. The method presented an excellent intra- and inter-assay imprecision and bias (<10.7%) at each measured concentration of two external quality controls (QC) and three "in house" QC. No matrix effects were observed and good recoveries (>70%) were obtained for all the compounds. No carryover was observed after the analysis of high concentrated samples (8000 ng/mL). The method was subsequently applied to authentic samples.

  12. Determination of thalidomide concentration in human plasma by liquid chromatography-tandem mass spectrometry.

    PubMed

    Bai, Nan; Cui, Xiang-Yong; Wang, Jin; Sun, Chun-Guang; Mei, He-Kun; Liang, Bei-Bei; Cai, Yun; Song, Xiu-Jie; Gu, Jing-Kai; Wang, Rui

    2013-02-01

    A rapid, sensitive and specific analytical method based on high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed for the determination of thalidomide concentration in human plasma. The analyte and internal standard were extracted by liquid-liquid extraction with ether-dichloromethane (3:2, v/v) and separated on a TC-C(18) column using methanol-10 mM ammonium acetate-formic acid (60:40:0.04, v/v/v) as the mobile phase at a flow rate of 0.9 ml/min. The detection was performed using an API 4000 triple quadrupole mass spectrometer in the positive electrospray ionization (ESI) mode and completed within 3.0 min. The multiple reaction monitoring (MRM) transitions were m/z 259.1→84.0 for the analyte and m/z 195.9→138.9 for temozolomide. The calibration curve exhibited a linear dynamic range of 2-1500 ng/ml (r>0.9991). The intra-and inter-day precisions (as relative standard deviation; RSD) were 6.8-13.5% and 4.3-5.0% respectively and the accuracy (as relative error; RE) was 2.0-3.5%. The recoveries and matrix effects were satisfactory in all the biological matrices examined. This method was successfully used in a pharmacokinetic study of thalidomide in healthy male volunteers receiving an oral administration of a 200-mg dose.

  13. [Effects of ionic liquids on micellar microstructures and separation performance in micellar electrokinetic chromatography].

    PubMed

    Yu, Meijuan; Hang, Dong; Cao, Yuhua

    2011-02-01

    The effects of ionic liquids on micellar microstructures and separation performance in micellar electrokinetic chromatography (MEKC) were investigated. The experimental results showed that the addition of ionic liquids into micellar system would result in a decreased micellar surface charge density, an enlarged size of micelle and a slight enhancement of the polarity in the inner core of micelle. Prednisone, hydrocortisone and prednisolone were analyzed with MEKC to evaluate the separation performance. Hydrocortisone and prednisolone could not be separated in sodium lauryl sulfate (SDS) micellar system. However, the three analytes could be baseline separated in the mixed system of ionic liquids and SDS (20 mmol/L SDS-10 mmol/L 1-butyl-3-methyl imidazolium tetrafluoroborate-50 mmol/L borax, pH 8.4) within 17 min. Notably, the linearities of the three analytes ranged from 2 to 100 mg/L and the detection limits based on the ratio of signal to noise of 3 were 1.0, 1.1 and 1.0 mg/L for prednisone, hydrocortisone and prednisolone, respectively. The method has been used in the analysis of corticosteroids in cosmetic samples. The recoveries for the three analytes were between 95. 1% and 117%. This method has the advantages of simple pretreatment, high accuracy, good reproducibility, and can be applied to the quality control of cosmetics.

  14. Determination of Harmine and Harmaline in Peganum harmala Seeds by High-Performance Liquid Chromatography

    NASA Astrophysics Data System (ADS)

    Monsef-Esfahani, Hamid Reza; Faramarzi, Mohammad Ali; Mortezaee, Venus; Amini, Mohsen; Rouini, Mohammad Reza

    A High-Performance Liquid Chromatography (HPLC) method was developed for determination of harmine, harmaline, harmol and harmalol in the extract of Peganum harmala seeds. The sample preparation was performed using liquid-liquid extraction. Chromatographic separation was achieved with a Tracer Excel 120 ODSA (150x4.6 mm) column, using a mixture of potassium phosphate buffer (10 mM, pH 7.0): acetonitrile (100:30; v/v) as mobile phase, in an isocratic mode at 1.5 mL min-1. UV detection (λ = 330 nm) was used. The calibration curves were linear (r2>0.998) in the concentration range of 0.5-20 μg mL-1 for all analytes. The lower limit of quantification for all analytes was 0.5 μg mL-1. The within and between day precisions in the measurement of QC samples at three tested concentrations were in the range of 0.6-10.2% for all analytes. The HPLC method is able to measure the harmala alkaloids in the plant extract. The method has suitable reproducibility, sensitivity and resolution for routine and accurate use with UV detection.

  15. Metabolism profiles of nuciferine in rats using ultrafast liquid chromatography with tandem mass spectrometry.

    PubMed

    Ye, Lin-Hu; Xiao, Bing-Xin; Liao, Yong-Hong; Liu, Xin-Min; Pan, Rui-Le; Chang, Qi

    2016-08-01

    Nuciferine (NF) is one of the main aporphine alkaloids existing in the traditional Chinese medicine Folium Nelumbinis (lotus leaves). Modern pharmacological studies have demonstrated that NF has a broad spectrum of bioactivities, such as anti-HIV and anti-hyperlipidemic effects, and has been recommended as a leading compound for new drug development. However, the metabolites and biotransformation pathway of NF in vivo have not yet been comprehensively investigated. The present study was performed to identify the metabolites of NF for exploring in vivo fates. Rat plasma and urine samples were collected after oral administration and prepared by liquid-liquid extraction with ethyl acetate. A method based on ultrafast liquid chromatography with tandem mass spectrometry was applied to identify the metabolites. Q1 (first quadrupole) full scan combined with a multiple reaction monitoring (MRM) survey scan were used for the detection of metabolites. MRM-information-dependent acquisition of enhanced product ions was used for the structural identification of detected metabolites. A total of 10 metabolites were identified, including phase I (demethylation, oxidation and dehydrogenation) and phase II (glucuronidation, sulfation and glutathione) biotransformation products. Demethylation is the main metabolic pathway of NF in the body. These results can help in improving understanding of the disposition and pharmacological mechanism of NF in the body. Copyright © 2016 John Wiley & Sons, Ltd.

  16. Determination of tolperisone in human plasma by liquid chromatography/tandem mass spectrometry for clinical application.

    PubMed

    Choi, Chang-Ik; Park, Jung-In; Lee, Hye-In; Lee, Yun-Jeong; Jang, Choon-Gon; Bae, Jung-Woo; Lee, Seok-Yong

    2012-12-12

    We have developed and validated a simple, rapid, and sensitive liquid chromatography analytical method employing tandem mass spectrometry (LC-MS/MS) for the determination of tolperisone, a centrally acting muscle relaxant, in human plasma. After liquid-liquid extraction with methyl t-butyl ether, chromatographic separation of tolperisone was performed using a reversed-phase Luna C(18) column (2.0mm×50mm, 5μm particles) with a mobile phase of 10mM ammonium formate buffer (pH 3.5) - methanol (12:88, v/v) and quantified by tandem mass detection in ESI positive ion mode. The flow rate of the mobile phase was 250μL/min and the retention times of tolperisone and the internal standard (IS, dibucaine) were both 0.6min. The calibration curves were linear over a range of 0.5-300ng/mL (r>0.999). The lower limit of quantification, using 200μL human plasma, was 0.5ng/mL. The mean accuracy and precision for intra- and inter-day validation of tolperisone were within acceptable limits. The LC-MS/MS method reported here showed improved sensitivity for quantification of tolperisone in human plasma compared with previously described analytical methods. Lastly, the validated method was successfully applied to a pharmacokinetic study in humans.

  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. Simultaneous Determination of Eight Bioactive Compounds in Dianthus superbus by High-performance Liquid Chromatography

    PubMed Central

    Yun, Bo-Ra; Yang, Hye Jin; Weon, Jin Bae; Lee, Jiwoo; Eom, Min Rye; Ma, Choong Je

    2016-01-01

    Background: Dianthus superbus, one of traditional herbal medicine, is widely used to treat urethritis, carbuncles and carcinoma. Objective: A simultaneous determination method was established for controlling the quality of D. superbus using the eight compounds, (E)-methyl-4-hydroxy-4-(8a-methyl-3-oxodecahydronaphthalen-4a-yl) (1), diosmetin-7-O(2'',6''-di-O-α-L-rhamnopyranosyl)-β-D-glucopyranoside (2), vanillic acid (3), 4-hydroxyphenyl acetic acid (4), 4-methoxyphenyl acetic acid (5), (E)-4-methoxycinnamic acid (6), 3-methoxy-4-hydroxyphenylethanol (7), and methyl hydroferulate (8) isolated from D. superbus. Materials and Methods: This analysis method was developed using high performance liquid chromatography coupled with diode array detector with a Shishedo C18 column at a column temperature of 3°C. The mobile phase was composed of 0.1% trifluoroacetic acid in water and acetonitrile. The flow rate was 1 ml/min and detection wavelength was set at 205 nm and 280 nm. Validation was performed in order to demonstrate selectivity, accuracy and precision of the method. Results: The calibration curves showed good linearity (R2 > 0.99). The limits of detection and limits of quantification were within the ranges 0.0159–0.6205 μg/ml and 0.3210–1.8802 μg/ml, respectively. Moreover, the relative standard deviations of intra- and inter-day precision were both <2.98%. The overall recoveries were in the range of 96.23–109.87%. Quantitative analysis of eight compounds in 12 D. superbus samples (D-1–D-12) from various regions were analyzed and compared by developed method. Conclusion: As a result, this established method was accurate and sensitive for the quality evaluation of eight compounds isolated from D. superbus and may provide a new basis for quality control of D. superbus. SUMMARY A simultaneous determination method of eight compounds in Dianthus superbus was established by high performance liquid chromatography-diode array detectorDeveloped analysis method is

  19. Towards Single-Step Biofabrication of Organs on a Chip via 3D Printing.

    PubMed

    Knowlton, Stephanie; Yenilmez, Bekir; Tasoglu, Savas

    2016-09-01

    Organ-on-a-chip engineering employs microfabrication of living tissues within microscale fluid channels to create constructs that closely mimic human organs. With the advent of 3D printing, we predict that single-step fabrication of these devices will enable rapid design and cost-effective iterations in the development stage, facilitating rapid innovation in this field.

  20. Single step signal group-imidazole labeling of organic phosphate groups under aqueous conditions

    DOEpatents

    Giese, Roger W.; Wang, Poguang

    1996-01-01

    Compounds and methods for single step, covalent labeling of the phosphate group of an organic substance under aqueous conditions are described. The labeling compound includes any kind of detectable signal group covalently bound to an imidazole moiety, which can be imidazole or a substituted imidazole. A preferred labeling compound has the formula ##STR1##