Sample records for chromatography-mass spectrometry analysis

  1. ANALYSIS OF TECHNICAL CHLORDANE BY GAS CHROMATOGRAPHY MASS SPECTROMETRY

    EPA Science Inventory

    The composition of technical chlordane has been investigated by combined gas chromatography/mass spectrometry, employing a column commonly used for pesticide residue analysis. Partial or complete structure identification have been assigned to some 45 individual constituents. Many...

  2. Targeted analysis of glycomics liquid chromatography\\/mass spectrometry data

    Microsoft Academic Search

    Jonathan M. Dreyfuss; Christopher Jacobs; Yevgeniy Gindin; Gary Benson; Gregory O. Staples; Joseph Zaia

    2011-01-01

    Hydrophilic interaction chromatography (HILIC) liquid chromatography\\/mass spectrometry (LC\\/MS) is appropriate for all native\\u000a and reductively aminated glycan classes. HILIC carries the advantage that retention times vary predictably according to oligosaccharide\\u000a composition. Chromatographic conditions are compatible with sensitive and reproducible glycomics analysis of large numbers\\u000a of samples. The data are extremely useful for quantitative profiling of glycans expressed in biological tissues.

  3. ORGANIC WATER POLLUTANT ANALYSIS BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY

    EPA Science Inventory

    Gas chromatography-mass spectrometry is a widely used technique for the identification of organic chemicals in water. This paper describes the gas chromatograph-mass spectrometer system, the preparation and separation of samples, the selection of ionizing processes, the integrati...

  4. VACUUM DISTILLATION COUPLED WITH GAS CHROMATOGRAPHY/MASS SPECTROMETRY FOR THE ANALYSIS OF ENVIRONMENTAL SAMPLES

    EPA Science Inventory

    A procedure is presented that uses a vacuum distillation/gas chromatography/mass spectrometry system for analysis of problematic matrices of volatile organic compounds. The procedure compensates for matrix effects and provides both analytical results and confidence intervals from...

  5. COMPARATIVE EVALUATION OF GC/MS (GAS CHROMATOGRAPHY/MASS SPECTROMETRY) DATA ANALYSIS PROCESSING

    EPA Science Inventory

    Mass spectra obtained by fused silica capillary gas chromatography/mass spectrometry/data system (GC/MS/DS) analysis of mixtures of organic chemicals adsorbed on Tenax GC cartridges was subjected to manual and automated interpretative techniques. Synthetic mixtures (85 chemicals ...

  6. Analysis of waterborne paints by gas chromatography–mass spectrometry with a temperature-programmable pyrolyzer

    Microsoft Academic Search

    Sadao Nakamura; Masahiko Takino; Shigeki Daishima

    2001-01-01

    Gas chromatography–mass spectrometry (GC–MS) with a temperature-programmable pyrolyzer was used for the analysis of waterborne paints. Evolved gas analysis (EGA) profiles of the waterborne paints were obtained by this temperature-programmed pyrolysis directly coupled with MS via a deactivated metal capillary tube. The EGA profile suggested the optimal thermal desorption conditions for solvents and additives and the subsequent optimal pyrolysis temperature

  7. Analysis of sugars in environmental samples by gas chromatography–mass spectrometry

    Microsoft Academic Search

    Patricia M. Medeiros; Bernd R. T. Simoneit

    2007-01-01

    Many environmental samples contain complex mixtures of organic compounds with different sources, polarities and reactivities. This study reports a method for the analysis of both polar\\/water-soluble and apolar organic compounds in several kinds of environmental samples. The analytical method consists of extraction with a mixture of dichloromethane:methanol (2:1, v\\/v), silylation using BSTFA (N,O-bis-(trimethylsilyl)trifluoroacetamide) and analysis by gas chromatography–mass spectrometry (GC–MS),

  8. Rapid Analysis of Multiresidual Pesticides in Agricultural Products by Gas Chromatography-mass Spectrometry

    Microsoft Academic Search

    Libin Liu; Hashi Yuki; Yaping Qin; Haixia Zhou; Jinming Lin

    2006-01-01

    A method for the rapid analysis of multiresidual pesticides in agricultural products using gas chromatography-mass spectrometry (GC\\/MS) was introduced. The matrix solid-phase dispersion (MSPD) technique with slight modification was employed to minimize the matrix interferences. To calculate the recovery, 97 target pesticides were spiked into a range of foods including potato, cabbage, carrot, apple, orange, cucumber, and rice. The combination

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

    PubMed

    Rao, Ramisetti Nageswara

    2014-08-01

    Dried blood spots (DBS), a micro blood sampling technique, has recently gained interest in drug discovery and development due to its inherent advantages over the conventional whole blood, plasma or serum sample collection. Since the regulatory authorities have agreed to the use of blood as an acceptable biological matrix for drug exposure measurements, its applications have been extended not only to therapeutic drug monitoring but also to toxicokinetic and pharmacokinetic studies. The pharmaceutical industry is keen to promote DBS as a prominent tool in bioanalytical applications due to the financial, ethical and organizational issues involved in clinical trials. This could be accomplished due to the latest advances in modern analytical technology, particularly liquid chromatography-mass spectrometry. The present review discusses some of the emerging liquid chromatography-mass spectrometry technologies in improving DBS analysis for its innovative applications in the development of new drugs. PMID:24697571

  10. Analysis of psilocybin and psilocin in Psilocybe subcubensis GUZMÁN by ion mobility spectrometry and gas chromatography–mass spectrometry

    Microsoft Academic Search

    Thomas Keller; Andrea Schneider; Priska Regenscheit; Richard Dirnhofer; Thomas Rücker; Jürgen Jaspers; Wolfgang Kisser

    1999-01-01

    A new method has been developed for the rapid analysis of psilocybin and\\/or psilocin in fungus material using ion mobility spectrometry. Quantitative analysis was performed by gas chromatography–mass spectrometry after a simple one-step extraction involving homogenization of the dried fruit bodies of fungi in chloroform and derivatization with MSTFA. The proposed methods resulted in rapid procedures useful in analyzing psychotropic

  11. Microwave-assisted derivatization procedures for gas chromatography\\/mass spectrometry analysis

    Microsoft Academic Search

    Sandra L. Söderholm; Markus Damm; C. Oliver Kappe

    2010-01-01

    In this review, published applications of microwave-assisted derivatization procedures for gas chromatography\\/mass spectrometry\\u000a (GC\\/MS) are summarized. Among the broad range of analytical techniques available, GC\\/MS is still the method of choice for\\u000a most high-throughput screening procedures in forensic\\/clinical toxicology, doping control and food and environmental analysis.\\u000a Despite the many advantages of the GC\\/MS method, time-consuming derivatization steps are often required

  12. Verification of chemical composition of commercially available propolis extracts by gas chromatography-mass spectrometry analysis.

    PubMed

    Czy?ewska, Urszula; Kono?czuk, Joanna; Teul, Joanna; Dr?gowski, Pawe?; Pawlak-Morka, Renata; Sura?y?ski, Arkadiusz; Miltyk, Wojciech

    2015-05-01

    Propolis is a resin that is collected by honeybees from various plant sources. Due to its pharmacological properties, it is used in commercial production of nutritional supplements in pharmaceutical industry. In this study, gas chromatography-mass spectrometry was applied for quality control analysis of the three commercial specimens containing aqueous-alcoholic extracts of bee propolis. More than 230 constituents were detected in analyzed products, including flavonoids, chalcones, cinnamic acids and their esters, phenylpropenoid glycerides, and phenylpropenoid sesquiterpenoids. An allergenic benzyl cinnamate ester was also identified in all tested samples. This analytical method allows to evaluate biological activity and potential allergenic components of bee glue simultaneously. Studies on chemical composition of propolis samples may provide new approach to quality and safety control analysis in production of propolis supplementary specimens. PMID:25198412

  13. Applied analysis of lacquer films based on pyrolysis-gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    Rong Lu; Yukio Kamiya; Tetsuo Miyakoshi

    2006-01-01

    Ancient lacquer film, a Nanban lacquer film, an old lacquer-ware object imported from an Asian country, and the Baroque and Rococo lacquer films were analyzed by pyrolysis-gas chromatography\\/mass spectrometry. Compared with the results of the natural lacquer film, it was revealed that the ancient lacquer film and Nanban lacquer film were made from Rhus vernicifera, and the old lacquer-ware imported

  14. Multiresidue analysis of pesticides in fruits and vegetables by gas chromatography-mass spectrometry

    Microsoft Academic Search

    M. Araoud; W. Douki; A. Rhim; M. F. Najjar; N. Gazzah

    2007-01-01

    A multiresidue method was assessed for the determination of several pesticides (organochlorine, organophosphorus, pyrethroids, triazole, amidine) using gas chromatography\\/mass spectrometry. The extraction of pesticides was carried out by liquid-liquid extraction (LLE) and solid-phase extraction (SPE) using two types of columns (CN and C18). The extracts were cleaned by the addition of florisil, the pesticides were separated by capillary column gas

  15. Headspace Analysis of Philippine Civet Coffee Beans Using Gas Chromatography-Mass Spectrometry and Electronic Nose

    NASA Astrophysics Data System (ADS)

    Ongo, E.; Sevilla, F.; Antonelli, A.; Sberveglieri, G.; Montevecchi, G.; Sberveglieri, V.; de Paola, E. L.; Concina, I.; Falasconi, M.

    2011-11-01

    Civet coffee, the most expensive and best coffee in the world, is an economically important export product of the Philippines. With a growing threat of food adulteration and counterfeiting, a need for quality authentication is essential to protect the integrity and strong market value of Philippine civet coffee. At present, there is no internationally accepted method of verifying whether a bean is an authentic civet coffee. This study presented a practical and promising approach to identify and establish the headspace qualitative profile of Philippine civet coffee using electronic nose (E-nose) and gas chromatography-mass spectrometry (GC-MS). E-nose analysis revealed that aroma characteristic is one of the most important quality indicators of civet coffee. The findings were supported by GC-MS analysis. Principal component analysis (PCA) exhibited a clearly separated civet coffees from their control beans. The chromatographic fingerprints indicated that civet coffees differed with their control beans in terms of composition and concentration of individual volatile constituents.

  16. Microwave-assisted derivatization procedures for gas chromatography/mass spectrometry analysis.

    PubMed

    Söderholm, Sandra L; Damm, Markus; Kappe, C Oliver

    2010-11-01

    In this review, published applications of microwave-assisted derivatization procedures for gas chromatography/mass spectrometry (GC/MS) are summarized. Among the broad range of analytical techniques available, GC/MS is still the method of choice for most high-throughput screening procedures in forensic/clinical toxicology, doping control and food and environmental analysis. Despite the many advantages of the GC/MS method, time-consuming derivatization steps are often required in order to obtain desirable chromatographic characteristics or to improve the stability and detectability of the target analytes. These derivatization processes typically require reaction times from 30 min up to several hours at elevated temperature. In contrast, microwave protocols have demonstrated to be able to reduce the time required for derivatization to a few minutes, and can thus very effectively shorten the overall analysis time, in particular when carried out in a high-throughput format. Herein, the literature in this field is summarized and recent experimental techniques for performing parallel GC/MS derivatization protocols are discussed. PMID:20225067

  17. Phthalate analysis by gas chromatography-mass spectrometry: blank problems related to the syringe needle.

    PubMed

    Marega, Milena; Grob, Konrad; Moret, Sabrina; Conte, Lanfranco

    2013-01-18

    For the analysis of the most commonly encountered phthalates by gas chromatography-mass spectrometry (GC-MS), absorption of phthalates from the laboratory air on the outer wall of the syringe needle is shown to be an important contribution to the blank problems. It was investigated for programmed temperature vapourizing (PTV) injection. Cleaning of the needle in automated injection is of modest efficiency, since the needle cannot be immersed deeply enough into the wash vial. Two approaches were studied to minimize the transfer into the column: (i) cleaning of the needle in the injector prior to splitless injection by inserting the needle in split mode while the precolumn is backflushed, which presupposes a high injector temperature to be efficient; (ii) injection under conditions minimizing thermal desorption from the needle wall, i.e. fast injection at low injector temperature (e.g. 40 °C). Both approaches resulted in blank levels of around 0.1 pg for diisobutyl phthalate (DIBP) and dibutyl phthalate (DBP), and of around 1 pg for di(2-ethylhexyl) phthalate (DEHP). They could be useful tools in existing or future methods for the analysis of phthalates or other compounds causing blank problems through contamination of the laboratory air. PMID:23265992

  18. Surface-sampling and analysis of TATP by swabbing and gas chromatography/mass spectrometry.

    PubMed

    Romolo, Francesco Saverio; Cassioli, Luigi; Grossi, Silvana; Cinelli, Giuseppe; Russo, Mario Vincenzo

    2013-01-10

    The method of sample recovery for trace detection and identification of explosives plays a critical role in several criminal investigations. After bombing, there can be difficulties in sending big objects to a laboratory for analysis. Traces can also be searched for on large surfaces, on hands of suspects or on surfaces where the explosive was placed during preparatory phases (e.g. places where an IED was assembled, vehicles used for transportation, etc.). In this work, triacetone triperoxide (TATP) was synthesized from commercial precursors following reported methods. Several portions of about 6mg of TATP were then spread on different surfaces (e.g. floors, tables, etc.) or used in handling tests. Three different swabbing systems were used: a commercial swab, pre-wetted with propan-2-ol (isopropanol) and water (7:3), dry paper swabs, and cotton swabs wetted with propan-2-ol. Paper and commercial swabs were also used to sample a metal plate, where a small charge of about 4g of TATP was detonated. Swabs were sealed in small glass jars with screw caps and Parafilm(®) M and sent to the laboratory for analysis. Swabs were extracted and analysed several weeks later by gas chromatography/mass spectrometry. All the three systems gave positive results, but wetted swabs collected higher amounts of TATP. The developed procedure showed its suitability for use in real cases, allowing TATP detection in several simulations, including a situation in which people wash their hands after handling the explosive. PMID:23219697

  19. In situ Analysis of Organic Compounds on Mars using Chemical Derivatization and Gas Chromatography Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Glavin, D. P.; Buch, A.; Cabane, M.; Coll, P.; Navarro-Gonzalez, R.; Mahaffy, P. R.

    2005-01-01

    One of the core science objectives of NASA's 2009 Mars Science Laboratory (MSL) mission is to determine the past or present habitability of Mars. The search for key organic compounds relevant to terrestrial life will be an important part of that assessment. We have developed a protocol for the analysis of amino acids and carboxylic acids in Mars analogue materials using gas chromatography mass spectrometry (GCMS). As shown, a variety of carboxylic acids were readily identified in soil collected from the Atacama Desert in Chile at part-per-billion levels by GCMS after extraction and chemical derivatization using the reagent N,N-tert.-butyl (dimethylsilyl) trifluoroacetamide (MTBSTFA). Several derivatized amino acids including glycine and alanine were also detected by GCMS in the Atacama soil at lower concentrations (chromatogram not shown). Lacking derivatization capability, the Viking pyrolysis GCMS instruments could not have detected amino acids and carboxylic acids, since these non-volatile compounds require chemical transformation into volatile species that are stable in a GC column. We are currently optimizing the chemical extraction and derivatization technique for in situ GCMS analysis on Mars. Laboratory results of analyses of Atacama Desert samples and other Mars analogue materials using this protocol will be presented.

  20. Comprehensive analysis of lipids in biological systems by liquid chromatography-mass spectrometry.

    PubMed

    Cajka, Tomas; Fiehn, Oliver

    2014-10-01

    Liquid chromatography-mass spectrometry (LC-MS)-based lipidomics has been a subject of dramatic developments over the past decade. This review focuses on state of the art in LC-MS-based lipidomics, covering all the steps of global lipidomic profiling. On the basis of review of 185 original papers and application notes, we can conclude that typical LC-MS-based lipidomics methods involve: (1) extraction using chloroform/MeOH or MTBE/MeOH protocols, both with addition of internal standards covering each lipid class; (2) separation of lipids using short microbore columns with sub-2-?m or 2.6-2.8-?m (fused-core) particle size with C18 or C8 sorbent with analysis time <30 min; (3) electrospray ionization in positive- and negative-ion modes with full spectra acquisition using high-resolution MS with capability to MS/MS. Phospholipids (phosphatidylcholines, phosphatidylethanolamines, phosphatidylinositols, phosphatidylserines, phosphatidylglycerols) followed by sphingomyelins, di- and tri-acylglycerols, and ceramides were the most frequently targeted lipid species. PMID:25309011

  1. The analysis of black powder substitutes containing ascorbic acid by ion chromatography/mass spectrometry.

    PubMed

    Lang, Gui-hua Lisa; Boyle, Katherine M

    2009-11-01

    Black powder substitutes containing ascorbic acid are a group of low explosives that utilize ascorbic acid as the fuel. The analysis of these powders is complicated by the degradation of ascorbic acid which occurs rapidly in solution and may also occur as the powder ages. Aqueous extracts of both intact powders and postblast residues were analyzed by an existing ion chromatography/mass spectrometry (IC/MS) method used at the Bureau of Alcohol, Tobacco, Firearms and Explosives. Results have shown that while ascorbic acid itself is not detected in this method, its diagnostic degradation products (threonic acid, monohydrated diketogulonic acid, and oxalic acid) can be identified. In addition, anions from the inorganic oxidizers (perchlorate and nitrate) and combustion products such as chloride, chlorate, and nitrite, can be identified within the same experiment. While this IC/MS method shows promise, future modifications are necessary because of limitations in identifying threonate in postblast residues, as well as coeluting compounds observed in postblast residues. PMID:19732276

  2. 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. PMID:18785191

  3. Analysis of aliphatic biopolymers using thermochemolysis with tetramethylammonium hydroxide (TMAH) and gas chromatography- mass spectrometry

    Microsoft Academic Search

    PATRICK G. HATCHER

    1998-01-01

    Abstract—Selected aliphatic biopolyesters (cutins, cuticles and a suberin) isolated from diÄerent plants have,been,analyzed,using thermochemolysis,with,tetramethylammonium,hydroxide,(TMAH). This method consists of a high-temperature saponification\\/transesterification, and yields methyl esters of fatty acids and the methyl ethers of alcohols, which are subsequently analyzed by gas chromatography and,gas chromatography?mass spectrometry. The main,compounds,produced,from,the analyzed samples correspond to the methyl derivatives of long-chain fatty acids, hydroxy fatty acids

  4. Analysis of isothiazolinones in environmental waters by gas chromatography–mass spectrometry

    Microsoft Academic Search

    Astrid Rafoth; Sabine Gabriel; Frank Sacher; Heinz-Jürgen Brauch

    2007-01-01

    This paper describes an analytical method for the determination of five biocides of isothiazolinone type (2-methyl-3-isothiazolinone (MI), 5-chloro-2-methyl-3-isothiazolinone (CMI), 1,2-benzisothiazolinone (BIT), 2-octyl-3-isothiazolinone (OI), 4,5-dichloro-2-octyl-3-isothiazolinone (DCOI)) in environmental waters. The method is based on pre-concentration of the analytes by solid-phase extraction onto a mixture of a polymeric material and RP-C18 material and subsequent determination by gas chromatography–mass spectrometry (GC–MS). One of

  5. Thermal Degradation Behavior of Waste Video Cards Using Thermogravimetric Analysis and Pyrolysis Gas Chromatography\\/Mass Spectrometry Techniques

    Microsoft Academic Search

    Huabo Duan; Jinhui Li; Jyh-Feng Hwang; Wang Chen; Elisabeth Gilmore; Peter Adams; Lester Lave; Weifeng Jia; Violeta Mugica; Sara Hernandez; Miguel Torres; Rocio García; Antton Melendez; Estibaliz García; Pedro Carnicer; Egoitz Pena; Miren Larrion; Juan Legarreta; Cristina Gutierrez-Canas; Parikhit Sinha; William Schew; Aniket Sawant; Kyle Kolwaite; Sarah Strode; Stephanie Weber; Jill Engel-Cox; Raymond Hoff; Ana Prados; Hai Zhang; Valerie Garcia; Kristen Foley; Edith Gego; David Holland; S. Rao; Sundar Christopher; Pawan Gupta; Chengwen Wang; Yujue Wang; Yanqi Zhang; Qi Zhao; Ran Wang; Christian Murray; Frederick Lipfert; Jung-Nan Hsu; Hsunling Bai; Shou-Nan Li; Chuen-Jinn Tsai

    2010-01-01

    The thermal degradation characteristics of a printed circuit board assembly (PCBA), specifically video cards from waste computers, was studied using pyrolysis-gas chromatography-mass spectrometry (Py-GC\\/MS) and thermogravimetric analysis (TGA). The video-card waste was dismantled into substrate, integrated circuits (ICs), and plastic slots for comparable investigation. The results by TGA revealed that the initial temperature at which degradation began was 300 °C

  6. Analysis of 23 polycyclic aromatic hydrocarbons in smokeless tobacco by gas chromatography-mass spectrometry

    PubMed Central

    Stepanov, Irina; Villalta, Peter W.; Knezevich, Aleksandar; Jensen, Joni; Hatsukami, Dorothy; Hecht, Stephen S.

    2009-01-01

    Smokeless tobacco contains 28 known carcinogens and causes precancerous oral lesions and oral and pancreatic cancer. A recent study conducted by our research team identified 8 different polycyclic aromatic hydrocarbons (PAH) in U.S. moist snuff, encouraging further investigations of this group of toxicants and carcinogens in smokeless tobacco products. In this study, we developed a gas chromatography-mass spectrometry method that allows simultaneous analysis of 23 various PAH in smokeless tobacco after a simple two-step extraction and purification procedure. The method produced coefficients of variation under 10% for most PAH. The limits of quantitation for different PAH varied between 0.3 ng/g tobacco and 11 ng/g tobacco, starting with a 300-mg sample. The recovery of the stable isotope-labeled internal standards averaged 87%. The method was applied to analysis of 23 moist snuff samples that include various flavors of the most popular U.S. moist snuff brands, as well as 17 samples representing the currently marketed brands of spit-free tobacco pouches, a relatively new type of smokeless tobacco. The sum of all detected PAH in conventional moist snuff averaged 11.6 (± 3.7) µg/g dry weight, 20% of this amount being comprised by carcinogenic PAH. The levels of PAH in new spit-free tobacco products were much lower than those in moist snuff, the sum of all detected PAH averaging 1.3 (±0.28) µg/g dry weight. Our findings render PAH one of the most prevalent groups of carcinogens in smokeless tobacco, along with tobacco-specific nitrosamines. Urgent measures are required from the U.S. tobacco industry to modify manufacturing processes so that the levels of these toxicants and carcinogens in the U.S. moist snuff are greatly reduced. PMID:19860436

  7. Analysis of acetylene in blood and urine using cryogenic gas chromatography-mass spectrometry.

    PubMed

    Kashiwagi, Masayuki; Hara, Kenji; Fujii, Hiroshi; Kageura, Mitsuyoshi; Takamoto, Mutsuo; Matsusue, Aya; Sugimura, Tomoko; Kubo, Shin-ichi

    2009-09-01

    A method for quantitative analysis of acetylene in blood and urine samples was investigated. Using cryogenic gas chromatography-mass spectrometry (GC-MS), acetylene was measured with isobutane as the internal standard in the headspace method, which revealed a linear response over the entire composite range with an excellent correlation coefficient, both in blood (R = 0.9968, range = 5.39-43.1 microg/ml) and urine (R = 0.9972, range = 2.16-10.8 microg/ml). The coefficients of variation (CV) for blood ranged from 2.62 to 11.6% for intra-day and 4.55 to 10.4% for inter-day. The CV for urine ranged from 2.38 to 3.10% for intra-day and 4.83 to 11.0% for inter-day. The recovery rate as an index of accuracy ranged from 83 to 111%. The present method showed good reliability, and is also simple and rapid. In actual samples from a charred cadaver due to acetylene explosion, the measured concentrations of acetylene by this method were 21.5 microg/ml for femoral vein blood, 17.9 microg/ml for right atrial blood, 25.5 microg/ml for left atrial blood and 7.49 microg/ml for urine. Quantification of acetylene provides important information, because the acetylene concentration is a vital reaction or sign. For example, when acetylene is filled in a closed space and then explodes, in antemortem explosion, the blood acetylene concentration of the cadaver might be significant. On the other hand, in postmortem explosion, acetylene is not detected in blood. Furthermore, when several victims are involved in one explosion, comparison of the sample concentrations can also provide useful information to establish the conditions at the accident scene; therefore, the present method is useful in forensics. PMID:19423404

  8. Linker-assisted immunoassay and liquid chromatography/mass spectrometry for the analysis of glyphosate

    USGS Publications Warehouse

    Lee, E.A.; Zimmerman, L.R.; Bhullar, B.S.; Thurman, E.M.

    2002-01-01

    A novel, sensitive, linker-assisted enzyme-linked immunosorbent assay (L'ELISA) was compared to on-line solidphase extraction (SPE) with high-performance liquid chromatography/mass spectrometry (HPLC/MS) for the analysis of glyphosate in surface water and groundwater samples. The L'ELISA used succinic anhydride to derivatize glyphosate, which mimics the epitotic attachment of glyphosate to horseradish peroxidase hapten. Thus, L'ELISA recognized the derivatized glyphosate more effectively (detection limit of 0.1 ??g/L) and with increased sensitivity (10-100 times) over conventional ELISA and showed the potential for other applications. The precision and accuracy of L'ELISA then was compared with on-line SPE/HPLC/MS, which detected glyphosate and its degradate derivatized with 9-fluorenylmethyl chloroformate using negative-ion electrospray (detection limit 0.1 ??g/L, relative standard deviation ??15%). Derivatization efficiency and matrix effects were minimized by adding an isotope-labeled glyphosate (2-13C15N). The accuracy of L'ELISA gave a false positive rate of 18% between 0.1 and 1.0 ??g/L and a false positive rate of only 1% above 1.0 ??g/L. The relative standard deviation was ??20%. The correlation of L'ELISA and HPLC/MS for 66 surface water and groundwater samples was 0.97 with a slope of 1.28, with many detections of glyphosate and its degradate in surface water but not in groundwater.

  9. Analysis of paralytic shellfish toxins using high-field asymmetric waveform ion mobility spectrometry with liquid chromatography-mass spectrometry.

    PubMed

    Beach, Daniel G; Melanson, Jeremy E; Purves, Randy W

    2015-03-01

    The analysis of paralytic shellfish toxins (PSTs) by liquid chromatography-mass spectrometry remains a challenge because of their high polarity, large number of analogues and the complex matrix in which they occur. Here we investigate the potential utility of high-field asymmetric waveform ion mobility spectrometry (FAIMS) as a gas-phase ion separation tool for analysis of PSTs by mass spectrometry. We investigate the separation of PSTs using FAIMS with two divergent goals: using FAIMS as a primary separation tool for rapid screening by electrospray ionization (ESI)-FAIMS-MS or combined with LC in a multidimensional LC-ESI-FAIMS-MS separation. First, a survey of the parameters that affect the sensitivity and selectivity of PST analysis by FAIMS was carried out using ESI-FAIMS-MS. In particular, the use of acetonitrile as a gas additive in the carrier gas flow offered good separation of all PST epimeric pairs. A second set of FAIMS conditions was also identified, which focussed PSTs to a relatively narrow CV range allowing development of an LC-ESI-FAIMS-MS method for analysis of PST toxins in complex mussel tissue extracts. The quantitative capabilities of this method were evaluated by analysing a PST containing mussel tissue matrix material. Results compared favourably with analysis by an established LC-post-column oxidation-fluorescence method with recoveries ranging from 70 to 106%, although sensitivity was somewhat reduced. The current work represents the first successful separation of PST isomers using ion mobility and shows the promise of FAIMS as a tool for analysis of algal biotoxins in complex samples and outlines some critical requirements for its future improvement. PMID:25619987

  10. [Analysis of cracking gas compressor fouling by pyrolysis gas chromatography-mass spectrometry].

    PubMed

    Hu, Yunfeng; Fang, Fei; Wei, Tao; Liu, Shuqing; Jiang, Guangshen; Cai, Jun

    2013-06-01

    The fouling from the different sections of the cracked gas compressor in Daqing Petrochemical Corporation was analyzed by pyrolysis gas chromatography-mass spectrometry (Py/GC-MS). All the samples were cracked in RJ-1 tube furnace cracker at the cracking temperature of 500 degrees C, and separated with a 60 m DB-1 capillary column. An electron impact ionization (EI) source was used with the ionizing voltage of 70 eV. The results showed the formation of fouling was closely related with cyclopentadiene which accounted for about 50% of the cracking products. Other components detected were 1-butylene, propylene, methane and n-butane. This Py/GC-MS method can be used as an effective approach to analyze the causes of fouling in the petrochemical plants. PMID:24063202

  11. On-line solid-phase extraction for liquid chromatography-mass spectrometry analysis of pesticides.

    PubMed

    Lucci, Paolo; Núñez, Oscar

    2014-10-01

    Public concern about pesticides in food and water has increased dramatically in the last two decades. In order to guarantee consumers' health and safety, analytical methods that could provide fast and reliable answers without compromising accuracy and precision are required. Sample treatment is probably the most tedious and time-consuming step in many analytical procedures and, despite the significant advances in chromatographic separations and mass spectrometry techniques, sample treatment is still one of the most important parts of the analytical process for achieving good analytical results. Therefore, over the last years, considerable efforts have been made to simplify the stage and to develop fast, accurate, and robust methods that allow the determination of a wide range of pesticides without compromising the integrity of the extraction process. This review article intends to give a short overview of recently developed on-line solid-phase extraction, preconcentration, and clean-up procedures for the determination of pesticides in complex matrices by liquid chromatography-mass spectrometry techniques. PMID:25103367

  12. Multiresidue analysis of pesticides in fruits and vegetables by gas chromatography-mass spectrometry.

    PubMed

    Araoud, M; Douki, W; Rhim, A; Najjar, M F; Gazzah, N

    2007-02-01

    A multiresidue method was assessed for the determination of several pesticides (organochlorine, organophosphorus, pyrethroids, triazole, amidine) using gas chromatography/mass spectrometry. The extraction of pesticides was carried out by liquid-liquid extraction (LLE) and solid-phase extraction (SPE) using two types of columns (CN and C18). The extracts were cleaned by the addition of florisil, the pesticides were separated by capillary column gas chromatography and detected by mass spectrometry in the electron impact mode. The extraction using C18 column provided the best results for most of the analyzed pesticides. The majority of pesticides recoveries from the four fruits and vegetables (apples, pears, tomatoes and pepper) were greater than 60%. Linearity and precision were satisfactory. The estimated limits of detection and limits of quantification ranged from 0.01 to 0.1 mg/kg and from 0.02 to 0.3 mg/kg, respectively. The proposed procedure was found to be useful for the multiresidue analyses of pesticides in agricultural products for routine monitoring programs. PMID:17365333

  13. Analysis of the scent gland secretions of Dumeril's ground boa (Acrantophis dumerili Jan) by gas chromatography-mass spectrometry

    E-print Network

    Simpson, John Thomas

    1989-01-01

    SIMPSON Approved to style and content by: Karl H. Dahm (Co-Chair of Committee) &9 Paul J. Weldon (Co-Chair of Committee) as . arp (Me er) Michael B. all (Head of Department) May 1989 ABSTRACT Analysis of the Scent Gland Secretions of Dumeri...Vs Ground Boa (Acranrophis dumerili Jan) by Gas Chromatography-Mass Spectrometry. (May 1989) John Thomas Simpson, B. S. , Louisiana State University Co-Chairs of Advisory Committee: Dr. Karl H. Dahm Dr. Paul J. Weldon When disturbed by predators, many...

  14. Multiclass mycotoxin analysis in food, environmental and biological matrices with chromatography/mass spectrometry.

    PubMed

    Capriotti, Anna Laura; Caruso, Giuseppe; Cavaliere, Chiara; Foglia, Patrizia; Samperi, Roberto; Laganà, Aldo

    2012-01-01

    Mold metabolites that can elicit deleterious effects on other organisms are classified as mycotoxins. Human exposure to mycotoxins occurs mostly through the intake of contaminated agricultural products or residues due to carry over or metabolite products in foods of animal origin such as milk and eggs, but can also occur by dermal contact and inhalation. Mycotoxins contained in moldy foods, but also in damp interiors, can cause diseases in humans and animals. Nephropathy, various types of cancer, alimentary toxic aleukia, hepatic diseases, various hemorrhagic syndromes, and immune and neurological disorders are the most common diseases that can be related to mycotoxicosis. The absence or presence of mold infestation and its propagation are seldom correlated with mycotoxin presence. Mycotoxins must be determined directly, and suitable analytical methods are necessary. Hundreds of mycotoxins have been recognized, but only for a few of them, and in a restricted number of utilities, a maximum acceptable level has been regulated by law. However, mycotoxins seldom develop alone; more often various types and/or classes form in the same substrate. The co-occurrence might render the individual mycotoxin tolerance dose irrelevant, and therefore the mere presence of multiple mycotoxins should be considered a risk factor. The advantage of chromatography/mass spectrometry (MS) is that many compounds can be determined and confirmed in one analysis. This review illustrates the state-of-the-art of mycotoxin MS-based analytical methods for multiclass, multianalyte determination in all the matrices in which they appear. A chapter is devoted to the history of the long-standing coexistence and interaction among humans, domestic animals and mycotoxicosis, and the history of the discovery of mycotoxins. Quality assurance, although this topic relates to analytical chemistry in general, has been also examined for mycotoxin analysis as a preliminary to the systematic literature excursus. Sample handling is a crucial step to devise a multiclass analytical method; so when possible, it has been treated separately for a better comparison before tackling the instrumental part of the whole analytical method. This structure has resulted sometimes in unavoidable redundancies, because it was also important to underline the interconnection. Most reviews do not deal with all the possible mycotoxin sources, including the environmental ones. The focus of this review is the analytical methods based on MS for multimycotoxin class determination. Because the final purpose to devise multimycotoxin analysis should be the assessment of the danger to health of exposition to multitoxicants of natural origin (and possibly also the interaction with anthropogenic contaminants), therefore also the analytical methods for environmental relevant mycotoxins have been thoroughly reviewed. Finally, because the best way to shed light on actual risk assessment could be the individuation of exposure biomarkers, the review covers also the scarce literature on biological fluids. PMID:22065561

  15. Analysis of isothiazolinones in environmental waters by gas chromatography-mass spectrometry.

    PubMed

    Rafoth, Astrid; Gabriel, Sabine; Sacher, Frank; Brauch, Heinz-Jürgen

    2007-09-14

    This paper describes an analytical method for the determination of five biocides of isothiazolinone type (2-methyl-3-isothiazolinone (MI), 5-chloro-2-methyl-3-isothiazolinone (CMI), 1,2-benzisothiazolinone (BIT), 2-octyl-3-isothiazolinone (OI), 4,5-dichloro-2-octyl-3-isothiazolinone (DCOI)) in environmental waters. The method is based on pre-concentration of the analytes by solid-phase extraction onto a mixture of a polymeric material and RP-C18 material and subsequent determination by gas chromatography-mass spectrometry (GC-MS). One of the target compounds (BIT) is derivatised with diazomethane after pre-concentration to improve its chromatographic performance. The method was optimised with respect to pre-concentration conditions (liquid-liquid extraction versus solid-phase extraction, solid-phase material, elution solvent and volume) and extensively validated. Applying the method to surface waters, groundwaters, and drinking waters, limits of detection between 0.01 and 0.1 microg/l could be achieved and the repeatability was below 10% for all compounds except for MI. Additional investigations showed that the stability of the isothiazolinones in environmental waters is limited and sample storage at 4 degrees C is mandatory to preserve the target biocides. First investigations of influents and effluents of a wastewater treatment plant showed that conventional wastewater treatment exhibits a high efficiency for removal of the isothiazolinones. In river waters, the target isothiazolinones could not be detected. PMID:17681349

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

    PubMed

    Huan, Tao; Li, Liang

    2015-07-21

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

  17. Headspace solid-phase microextraction gas chromatography-mass spectrometry analysis of Eupatorium odoratum extract as an oviposition repellent.

    PubMed

    Cui, Shufen; Tan, Shuo; Ouyang, Gangfeng; Jiang, Shihong; Pawliszyn, Janusz

    2009-07-01

    Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) analysis was used to study volatile and semi-volatile compounds emitted by the Eupatorium odoratum (E. odoratum) extract. Variables of HS-SPME such as the type of SPME fiber, extraction time and temperature, incubation time, desorption time and temperature have been optimized. Optimized conditions were obtained by the use of divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber, 5 min/20 min incubation/extraction time at 65 degrees C, 5 min desorption time at 260 degrees C. Using three different polar chromatographic columns to get retention index and mass spectrometry data, 99 volatile and semi-volatile compounds were tentatively identified in the E. odoratum extract. This study has identified the promising source of E. odoratum oviposition repellent. PMID:19501027

  18. Analysis of plant galactolipids by reversed-phase high-performance liquid chromatography/mass spectrometry with accurate mass measurement.

    PubMed

    Zábranská, Marie; Vrkoslav, Vladimír; Sobotníková, Jana; Cva?ka, Josef

    2012-07-01

    The composition of plant membrane lipids was investigated by reversed-phase high performance liquid chromatography mass spectrometry with accurate mass measurement. The data dependent methods for the analysis of monogalactosyldiacylglycerols (MGDGs) and digalactosyldiacylglycerols (DGDGs) have been developed. The optimised chromatographic systems were based on a 2.0 mm i.d. Nucleosil C18 column with methanol/water (MGDGs) or acetonitrile/methanol/water (DGDGs) gradients. The galactolipids were ionised by electrospray operated in the positive ion mode and identified based on their MS/MS spectra. High resolution spectra with accurate masses were found to be essential for correct interpretation of the MS data. The elution order of non-oxidised MGDGs and DGDGs followed the equivalent carbon numbers. The methods were applied for detailed characterisation of the MGDGs and DGDGs in the leaves of Arabidopsis thaliana and Melissa officinalis. PMID:22465211

  19. Accurate mass tag retention time database for urine proteome analysis by chromatography-mass spectrometry

    Microsoft Academic Search

    I. A. Agron; D. M. Avtonomov; A. S. Kononikhin; I. A. Popov; S. A. Moshkovskii; E. N. Nikolaev

    2010-01-01

    Information about peptides and proteins in urine can be used to search for biomarkers of early stages of various diseases.\\u000a The main technology currently used for identification of peptides and proteins is tandem mass spectrometry, in which peptides\\u000a are identified by mass spectra of their fragmentation products. However, the presence of the fragmentation stage decreases\\u000a sensitivity of analysis and increases

  20. Quantitative Analysis and Fingerprint Profiles for Quality Control of Fructus Schisandrae by Gas Chromatography: Mass Spectrometry

    PubMed Central

    Xia, Yong-Gang; Yang, Bing-You; Liang, Jun; Yang, Qi; Wang, Di; Kuang, Hai-Xue

    2014-01-01

    This paper describes a simple, rapid, and effective quality assessment method for Fructus Schisandrae by gas chromatography-mass spectrum (GC-MS). The method was established by using specific lignan fingerprint profiles and quantitation of characteristic compounds in this herbal medicine. The GC-MS fingerprints of 15 batches of Schisandra samples from different regions of China showed similar lignan profiles. Five peaks were selected as characteristic peaks, and all of these were identified by using GC-MS techniques. The relative retention times of these characteristic peaks in the GC-MS fingerprint were established as an important parameter for identification of Schisandra samples. Meanwhile, relative peak areas may be a feasible approach to discriminate the S. chinensis and S. sphenanthera. Finally, these pharmacologically active constituents in the titled plant, schisandrins A–C and schizandrols A and B, were quantitatively determined using a validated GC-MS method. PMID:24574919

  1. Analysis of vitamin D and its metabolites using thermospray liquid chromatography/mass spectrometry.

    PubMed

    Watson, D; Setchell, K D; Ross, R

    1991-07-01

    A new method is described for the analysis of vitamin D and its metabolites utilizing thermospray (TSP) mass spectrometry as an on-line detector for high performance liquid chromatography. Ionization conditions were optimized for use with isocratic reversed phase chromatography. TSP mass spectrometry was employed in series with a UV absorbance detector to facilitate comparisons between the two methods of detection. Positive ion TSP mass spectra were recorded for vitamin D2, vitamin D3, 25-hydroxyvitamin D3 (25(OH)D3), 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and 24,25-dihydroxyvitamin D3 (24,25(OH)2D3). The spectra contained protonated molecular ions, ammonium adduct ions and fragment ions due to the loss of one or more molecules of water. A comparison of quantitative precision was made by determining UV absorbance and TSP standard curves for vitamin D3 using two different methods: (1) External standard method with post-column (post UV detector) addition of ammonium acetate. (2) As (1) but using the method of internal standards with a closely eluting internal standard (vitamin D2). In each case the quantitative precision (correlation coefficient) for UV absorbance detection was superior owing to intrinsic instability of the TSP ion beam. A stable isotopically labelled internal standard was employed in the development of an assay for 1,25(OH)2D3. The assay was used to quantify in vitro enzymic conversion of 25(OH)D3 to 1,25(OH)2D3 in guinea pig and sheep renal mitochondrial incubations. TSP LC/MS was also applied to analysis of an extract of human blood plasma in which D3 and each of its principal metabolites were identified in a single analysis. PMID:1655127

  2. Disposable pipette extraction for the analysis of pesticides in fruit and vegetables using gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    Hongxia Guan; William E. Brewer; Sherry T. Garris; Stephen L. Morgan

    2010-01-01

    Organochlorine, organophosphate pesticides and fungicides in fruits and vegetables were analyzed using disposable pipette extraction (DPX) followed by gas chromatography–mass spectrometry-selective ion monitoring (GC\\/MS-SIM). The intrinsic rapid mixing capabilities of DPX result in fast and efficient extractions, and eluates are concentrated by using minimal elution solvent volumes rather than solvent evaporation methods. Matrix-matched calibrations were performed with reversed phase mechanisms

  3. Gas chromatography–mass spectrometry analysis of free and glycoconjugated aroma compounds of seasonally collected Satureja montana L

    Microsoft Academic Search

    J Masteli?; I Jerkovi?

    2003-01-01

    The present work examines the content and composition of glycoconjugated and free volatile aroma compounds in the plant material of savory, depending on the stage of plant development. Free volatile compounds (essential oil) as well as volatile aglycones obtained after the enzymatic hydrolysis of isolated glycosides were analyzed by coupled gas chromatography–mass spectrometry (GC–MS). Thirty-six compounds were identified in the

  4. [Matrix effects in analysis of three beta-agonist residues in pig edible tissues using gas chromatography-mass spectrometry].

    PubMed

    Bian, Kui; Lin, Tao; Liu, Min; Yang, Jianwen; Wang, Zongnan; He, Limin

    2014-02-01

    A gas chromatography-mass spectrometry (GC-MS) method was established for the determination of the residues of three beta-agonists (clenbuterol, salbutamol and ractopamine) in pig edible tissues. The matrix effects (MEs) in the analysis of the three compounds with the developed method were determined. The influences of matrix state and its weight on MEs were evaluated statistically. The analytes in pig liver and muscle and their corresponding freeze-dried powders were derivatized with N,O-bis(trimethylsilyl) trifluoroacetamide. Then the derivatives were determined in selected ion monitoring mode and the intensities of MEs of the three beta-agonists were obtained. Significant matrix enhancement was observed for the three analytes, and especially, the ME of ractopamine was more than 1000%. The results of analysis of variance (ANOVA) demonstrated that MEs were significantly different for the three analytes in two matrices among different matrix weights (P < 0.05), and MEs of the three analytes increased from 1 g to 5 g with the increase of matrix weight. MEs for the three analytes were not significantly different between fresh pig tissues and its freeze-dried powder matrices (P > 0.05), indicating that the freeze-dried powder matrices might be used to conveniently prepare the matrix-matched calibration solution, which could efficiently compensate the MEs of the beta-agonists in GC-MS analysis. PMID:24822451

  5. High Sensitivity Quantitative Lipidomics Analysis of Fatty Acids in Biological Samples by Gas Chromatography-Mass Spectrometry

    PubMed Central

    Quehenberger, Oswald; Armando, Aaron M.; Dennis, Edward A.

    2011-01-01

    Historically considered to be simple membrane components serving as structural elements and energy storing entities, fatty acids are now increasingly recognized as potent signaling molecules involved in many metabolic processes. Quantitative determination of fatty acids and exploration of fatty acid profiles have become common place in lipid analysis. We present here a reliable and sensitive method for comprehensive analysis of free fatty acids and fatty acid composition of complex lipids in biological material. The separation and quantitation of fatty acids is achieved by capillary gas chromatography. The analytical method uses pentafluorobenzyl bromide derivatization and negative chemical ionization gas chromatography-mass spectrometry. The chromatographic procedure provides base line separation between saturated and unsaturated fatty acids of different chain lengths as well as between most positional isomers. Fatty acids are extracted in the presence of isotope-labeled internal standards for high quantitation accuracy. Mass spectrometer conditions are optimized for broad detection capacity and sensitivity capable of measuring trace amounts of fatty acids in complex biological samples. PMID:21787881

  6. [Serum metabolomics analysis on benign prostate hyperplasia in mice based on liquid chromatography-mass spectrometry].

    PubMed

    Geng, Yue; Sun, Fengxia; Ma, Yu; Deng, Ligang; Lü, Jianyun; Li, Teng; Wang, Congcong

    2014-12-01

    Benign prostatic hyperplasia (BPH) increasingly becomes a common factor affecting the quality of life of aging men. Its pathogenesis has not yet been fully elucidated. Ultra-high pressure liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) was employed to detect the changes of serum metabolites in normal mice, benign prostatic hyperplasia model mice and BPH model mice with finasteride intervention. The serum metabolite profiles of the three groups of mice were analyzed. Partial least squares-discriminant analysis (PLS-DA) was used for group differentiation and biomarker selection. The results showed good distinction among the three groups of mice serum metabolite spectra. Three potential biomarkers, 1-hexadecanoyl-SN-glycero-3-phosphocholine, 1-O-hexadecyl-2-O-acetyl-sn-glyceryl-3-phosphorylcholine and (Z)-13-docosenamide, were discovered and identified. They all indicated the occurrence of benign prostatic hypertrophy is closely related to the disorders of lipid metabolism. Coinpared with the control group, the contents of the first two substances were significantly increased in the serum of BPH model mice, and significantly decreased after intervened by finasteride. The contents of (Z)-13-docosenamide decreased significantly in the serum of model group, and increased after intervened by finasteride. Compared with the control group, the contents of three biomarkers in finasteride group did not recover completely and had significant differences. This study is conductive to open new avenues of diagnosis and medical treatment for BPH. PMID:25902635

  7. Simple and rapid analysis of methyldibromo glutaronitrile in cosmetic products by gas chromatography mass spectrometry.

    PubMed

    Pellegrini, Manuela; Bossù, Elena; Rotolo, Maria Concetta; Pacifici, Roberta; Pichini, Simona

    2011-12-15

    A simple and rapid gas chromatography (GC) method with mass spectrometry (MS) detection has been developed for the determination of methyldibromo glutaronitrile (MDBGN) in cosmetic products. The presence of this preservative in commercial cosmetic samples is prohibited since 2007 because of its allergenic properties. The analyzed products were opportunely diluted in methanol and MDBGN was separated by fused silica capillary column and detected by electron impact (EI)-MS in positive ionization mode with a total run time of 7 min. The assay was validated in the range 0.005-0.100 mg MDBGN per g of examined product with good determination coefficients (r(2)?0.99) for the calibration curves. At three concentrations spanning the linear dynamic range of the calibration curves, mean recoveries were always higher than 95% for MDBGN in the tested cosmetics. This method was successfully applied to the analysis of cleansing gels, shampoo and solar waters to disclose the eventual presence of MDBGN illegally added in cosmetic products. PMID:21871753

  8. Chemical and technical challenges in the analysis of central carbon metabolites by liquid-chromatography mass spectrometry.

    PubMed

    Siegel, David; Permentier, Hjalmar; Reijngoud, Dirk-Jan; Bischoff, Rainer

    2014-09-01

    This review deals with chemical and technical challenges in the analysis of small-molecule metabolites involved in central carbon and energy metabolism via liquid-chromatography mass-spectrometry (LC-MS). The covered analytes belong to the prominent pathways in biochemical carbon oxidation such as glycolysis or the tricarboxylic acid cycle and, for the most part, share unfavorable properties such as a high polarity, chemical instability or metal-affinity. The topic is introduced by selected examples on successful applications of metabolomics in the clinic. In the core part of the paper, the structural features of important analyte classes such as nucleotides, coenzyme A thioesters or carboxylic acids are linked to "problematic hotspots" along the analytical chain (sample preparation and-storage, separation and detection). We discuss these hotspots from a chemical point of view, covering issues such as analyte degradation or interactions with metals and other matrix components. Based on this understanding we propose solutions wherever available. A major notion derived from these considerations is that comprehensive carbon metabolomics inevitably requires multiple, complementary analytical approaches covering different chemical classes of metabolites. PMID:24326023

  9. Practical aspects in gas chromatography-mass spectrometry for the analysis of pesticide residues in exotic fruits.

    PubMed

    España Amórtegui, Julio César; Guerrero Dallos, Jairo Arturo

    2015-09-01

    The most relevant parameters of a multimode inlet were optimized to increase the injection volume up to 25 ?L using solvent vent mode in order to improve the sensitivity of the gas chromatography-mass spectrometry system. Consequently, the implementation of a concurrent backflushing was necessary to largely prevent the expected loss of performance derived from such matrix load out of a general-purpose extraction (EN-15622-QuEChERS). Additionally, four mixtures of compounds used as analyte protectants were tested using spiked physalis to enhance the quality of signals. The chosen mixture remarkably improved sensitivity and yield better peak shapes, significantly more than others also tested. The analysis of pesticide residues in exotic fruits using instruments of limited selectivity is challenging since these complex matrices usually give notably dirty extracts. This scheme included an instrumental optimization and the addition of selected compounds that enabled to selectively reach limits of quantitation of 0.01 mg kg(-1) for most analytes. PMID:25842302

  10. Analysis of environmental samples for explosives and explosives degradation products by liquid chromatography-mass spectrometry

    SciTech Connect

    Gates, P.M.; Furlong, E.T.; Lindley, C.E.; Burkhardt, M.R. [Geological Survey, Arvada, CO (United States). National Water Quality Lab.

    1994-12-31

    Nitroaromatic explosives and their degradation products are regulated water-soluble contaminants that may pose a hazard to human health and could be important water contaminants. The reliable identification of most explosives, in particular, the identification of degradation products, is a major shortcoming in most analytical methods. As an improvement, high-performance liquid chromatography (HPLC) (coupled to Thermospray) mass spectrometry was used to determine compound molecular weights, and tandem-mass spectrometry was applied to confirm molecular structure. Compounds were separated isocratically using methanol-water with an octadecylsilane HPLC column. The identities of known nitroaromatic explosives were confirmed by combined ultraviolet absorbance and negative ion mass spectra. For optimal detection of known compounds, selected ion monitoring mass spectrometry was used. Calibration curves fit quadratic models, with correlation coefficients typically exceeding 0.995 over two orders of magnitude. Instrument detection limits ranged from 2.5 to 10 nanograms per injection, resulting in method-detection limits from about 100 to 400 nanograms per liter for a typical water sample. Unknown analytes (indicated by optical spectra) were identified by full scan and tandem mass spectrometry experiments on sample extracts or isolated extract fractions. This combined ultraviolet-diode array mass spectrometric approach is a superior method for analyzing soil or water samples where known explosives and unknown degradation products might be present.

  11. A liquid chromatography–mass spectrometry method for the quantitative analysis of urinary endogenous estrogen metabolites

    Microsoft Academic Search

    Xia Xu; Larry K Keefer; Regina G Ziegler; Timothy D Veenstra

    2007-01-01

    The ability to measure estrogen metabolites (EMs) quantitatively is important for investigating their individual roles in cancer screening, treatment and prevention, as well as in a host of other hormone-related disorders. In this protocol we describe a method that is capable of quantitating 15 distinct EMs in urine. Endogenous EMs are quantitatively measured using a liquid chromatography–tandem mass spectrometry method

  12. Simple and rapid analysis of methyldibromo glutaronitrile in cosmetic products by gas chromatography mass spectrometry

    Microsoft Academic Search

    Manuela Pellegrini; Elena Bossù; Maria Concetta Rotolo; Roberta Pacifici; Simona Pichini

    2011-01-01

    A simple and rapid gas chromatography (GC) method with mass spectrometry (MS) detection has been developed for the determination of methyldibromo glutaronitrile (MDBGN) in cosmetic products. The presence of this preservative in commercial cosmetic samples is prohibited since 2007 because of its allergenic properties. The analyzed products were opportunely diluted in methanol and MDBGN was separated by fused silica capillary

  13. Analysis of organic matter by flash pyrolysis-gas chromatography–mass spectrometry in the presence of Na-smectite: When clay minerals lead to identical molecular signature

    Microsoft Academic Search

    Pierre Faure; Laurent Jeanneau; Frederic Lannuzel

    2006-01-01

    Different studies have already pointed out the influence of clays during the analysis of pure organic compounds (especially alkanols, alkanoic acids) as well as macromolecules (humic acids) by flash pyrolysis-gas chromatography–mass spectrometry (PyGC–MS). Especially, the occurrence of clay minerals favors the generation of aromatic units such as alkylbenzenes and polycyclic aromatic hydrocarbons. So as to better identify the nature of

  14. Development and Application of Pyrolysis Gas Chromatography/Mass Spectrometry for the Analysis of Bound Trinitrotoluene Residues in Soil

    USGS Publications Warehouse

    Weiss, J.M.; Mckay, A.J.; Derito, C.; Watanabe, C.; Thorn, K.A.; Madsen, E.L.

    2004-01-01

    TNT (trinitrotoluene) is a contaminant of global environmental significance, yet determining its environmental fate has posed longstanding challenges. To date, only differential extraction-based approaches have been able to determine the presence of covalently bound, reduced forms of TNT in field soils. Here, we employed thermal elution, pyrolysis, and gas chromatography/mass spectrometry (GC/MS) to distinguish between covalently bound and noncovalently bound reduced forms of TNT in soil. Model soil organic matter-based matrixes were used to develop an assay in which noncovalently bound (monomeric) aminodinitrotoluene (ADNT) and diaminonitrotoluene (DANT) were desorbed from the matrix and analyzed at a lower temperature than covalently bound forms of these same compounds. A thermal desorption technique, evolved gas analysis, was initially employed to differentiate between covalently bound and added 15N-labeled monomeric compounds. A refined thermal elution procedure, termed "double-shot analysis" (DSA), allowed a sample to be sequentially analyzed in two phases. In phase 1, all of an added 15N-labeled monomeric contaminant was eluted from the sample at relatively low temperature. In phase 2 during high-temperature pyrolysis, the remaining covalently bound contaminants were detected. DSA analysis of soil from the Louisiana Army Ammunition Plant (LAAP; ???5000 ppm TNT) revealed the presence of DANT, ADNT, and TNT. After scrutinizing the DSA data and comparing them to results from solvent-extracted and base/acid-hydrolyzed LAAP soil, we concluded that the TNT was a noncovalently bound "carryover" from phase 1. Thus, the pyrolysis-GC/MS technique successfully defined covalently bound pools of ADNT and DANT in the field soil sample.

  15. Gas chromatography mass spectrometry computer analysis of volatile halogenated hydrocarbons in man and his environment--A multimedia environmental study.

    PubMed

    Barkley, J; Bunch, J; Bursey, J T; Castillo, N; Cooper, S D; Davis, J M; Erickson, M D; Harris, B S; Kirkpatrick, M; Michael, L C; Parks, S P; Pellizzari, E D; Ray, M; Smith, D; Tomer, K B; Wagner, R; Zweidinger, R A

    1980-04-01

    As part of a study to make a comparative analysis of selected halogenated compounds in man and the environmental media, a quantitative gas chromatography mass spectrometric analysis of the levels of the halogenated compounds found in the breath, blood and urine of an exposed population (Old Love Canal area, Niagara, New York) and their immediate environment (air and water) was undertaken. In addition, levels of halogenated hydrocarbons in air samples taken in the general Buffalo, Niagara Falls area were determined. PMID:7448328

  16. ANALYSIS OF HOUSTON AEROSOL SAMPLES BY GC/MS (GAS CHROMATOGRAPHY-MASS SPECTROMETRY) METHODS

    EPA Science Inventory

    An analysis procedure developed to give a qualitative and quantitative analysis for organic compounds adsorbed on aerosols collected by Hi-Vol filters was adapted and applied to a similar analysis of aerosols collected by dichotomous filters. Analysis was conducted for five dicho...

  17. Methods of analysis-Determination of pesticides in sediment using gas chromatography/mass spectrometry

    USGS Publications Warehouse

    Hladik, Michelle L.; McWayne, Megan M.

    2012-01-01

    A method for the determination of 119 pesticides in environmental sediment samples is described. The method was developed by the U.S. Geological Survey (USGS) in support of the National Water Quality Assessment (NAWQA) Program. The pesticides included in this method were chosen through prior prioritization. Herbicides, insecticides, and fungicides along with degradates are included in this method and span a variety of chemical classes including, but not limited to, chloroacetanilides, organochlorines, organophosphates, pyrethroids, triazines, and triazoles. Sediment samples are extracted by using an accelerated solvent extraction system (ASE®, and the compounds of interest are separated from co-extracted matrix interferences (including sulfur) by passing the extracts through high performance liquid chromatography (HPLC) with gel-permeation chromatography (GPC) along with the use of either stacked graphitized carbon and alumina solid-phase extraction (SPE) cartridges or packed Florisil®. Chromatographic separation, detection, and quantification of the pesticides from the sediment-sample extracts are done by using gas chromatography with mass spectrometry (GC/MS). Recoveries in test sediment samples fortified at 10 micrograms per kilogram (?g/kg) dry weight ranged from 75 to 102 percent; relative standard deviations ranged from 3 to 13 percent. Method detection limits (MDLs), calculated by using U.S. Environmental Protection Agency procedures (40 CFR 136, Appendix B), ranged from 0.6 to 3.4 ?g/kg dry weight.

  18. A chemometric-assisted method based on gas chromatography-mass spectrometry for metabolic profiling analysis.

    PubMed

    Yu, Yong-Jie; Fu, Hai-Yan; Zhang, Li; Wang, Xiao-Yu; Sun, Pei-Jian; Zhang, Xiao-Bing; Xie, Fu-Wei

    2015-06-19

    An automatic and efficient data analysis method for comprehensive metabolic profiling analysis is urgently required. In this study, a new chemometric-assisted method for metabolic profiling analysis (CAMMPA) was developed to discover potentially valuable metabolites automatically and efficiently. The proposed method mainly consists of three stages. First, automatic chromatographic peak detection is performed based on the total ion chromatograms of samples to extract chromatographic peaks that can be accurately quantified. Second, a novel peak-shift alignment technique based on peak detection results is implemented to resolve time-shift problems across samples. Consequently, aligned results, including aligned chromatograms, and peak area tables, among others, can be successfully obtained. Third, statistical analysis using results from unsupervised and supervised classification results, together with ANOVA and partial least square-discriminate analysis, is performed to extract potential metabolites. To demonstrate the proposed technique, a complex GC-MS metabolic profiling dataset was measured to identify potential metabolites in tobacco plants of different growth stages as well as different plant tissues after maturation. Results indicated that the efficiency of the routine metabolic profiling analysis procedure can be significantly improved and potential metabolites can be accurately identified with the aid of CAMMPA. PMID:25943833

  19. Chemometric Analysis of Gas ChromatographyMass Spectrometry Data using Fast Retention Time Alignment via a Total Ion Current Shift Function

    SciTech Connect

    Nadeau, Jeremy S.; Wright, Bob W.; Synovec, Robert E.

    2010-04-15

    A critical comparison of methods for correcting severely retention time shifted gas chromatography-mass spectrometry (GC-MS) data is presented. The method reported herein is an adaptation to the Piecewise Alignment Algorithm to quickly align severely shifted one-dimensional (1D) total ion current (TIC) data, then applying these shifts to broadly align all mass channels throughout the separation, referred to as a TIC shift function (SF). The maximum shift varied from (-) 5 s in the beginning of the chromatographic separation to (+) 20 s toward the end of the separation, equivalent to a maximum shift of over 5 peak widths. Implementing the TIC shift function (TIC SF) prior to Fisher Ratio (F-Ratio) feature selection and then principal component analysis (PCA) was found to be a viable approach to classify complex chromatograms, that in this study were obtained from GC-MS separations of three gasoline samples serving as complex test mixtures, referred to as types C, M and S. The reported alignment algorithm via the TIC SF approach corrects for large dynamic shifting in the data as well as subtle peak-to-peak shifts. The benefits of the overall TIC SF alignment and feature selection approach were quantified using the degree-of-class separation (DCS) metric of the PCA scores plots using the type C and M samples, since they were the most similar, and thus the most challenging samples to properly classify. The DCS values showed an increase from an initial value of essentially zero for the unaligned GC-TIC data to a value of 7.9 following alignment; however, the DCS was unchanged by feature selection using F-Ratios for the GC-TIC data. The full mass spectral data provided an increase to a final DCS of 13.7 after alignment and two-dimensional (2D) F-Ratio feature selection.

  20. Analysis of pharmaceutical and other organic wastewater compounds in filtered and unfiltered water samples by gas chromatography/mass spectrometry

    USGS Publications Warehouse

    Zaugg, Steven D.; Phillips, Patrick J.; Smith, Steven G.

    2014-01-01

    Research on the effects of exposure of stream biota to complex mixtures of pharmaceuticals and other organic compounds associated with wastewater requires the development of additional analytical capabilities for these compounds in water samples. Two gas chromatography/mass spectrometry (GC/MS) analytical methods used at the U.S. Geological Survey National Water Quality Laboratory (NWQL) to analyze organic compounds associated with wastewater were adapted to include additional pharmaceutical and other organic compounds beginning in 2009. This report includes a description of method performance for 42 additional compounds for the filtered-water method (hereafter referred to as the filtered method) and 46 additional compounds for the unfiltered-water method (hereafter referred to as the unfiltered method). The method performance for the filtered method described in this report has been published for seven of these compounds; however, the addition of several other compounds to the filtered method and the addition of the compounds to the unfiltered method resulted in the need to document method performance for both of the modified methods. Most of these added compounds are pharmaceuticals or pharmaceutical degradates, although two nonpharmaceutical compounds are included in each method. The main pharmaceutical compound classes added to the two modified methods include muscle relaxants, opiates, analgesics, and sedatives. These types of compounds were added to the original filtered and unfiltered methods largely in response to the tentative identification of a wide range of pharmaceutical and other organic compounds in samples collected from wastewater-treatment plants. Filtered water samples are extracted by vacuum through disposable solid-phase cartridges that contain modified polystyrene-divinylbenzene resin. Unfiltered samples are extracted by using continuous liquid-liquid extraction with dichloromethane. The compounds of interest for filtered and unfiltered sample types were determined by use of the capillary-column gas chromatography/mass spectrometry. The performance of each method was assessed by using data on recoveries of compounds in fortified surface-water, wastewater, and reagent-water samples. These experiments (referred to as spike experiments) consist of fortifying (or spiking) samples with known amounts of target analytes. Surface-water-spike experiments were performed by using samples obtained from a stream in Colorado (unfiltered method) and a stream in New York (filtered method). Wastewater spike experiments for both the filtered and unfiltered methods were performed by using a treated wastewater obtained from a single wastewater treatment plant in New York. Surface water and wastewater spike experiments were fortified at both low and high concentrations and termed low- and high-level spikes, respectively. Reagent water spikes were assessed in three ways: (1) set spikes, (2) a low-concentration fortification experiment, and (3) a high-concentration fortification experiment. Set spike samples have been determined since 2009, and consist of analysis of fortified reagent water for target compounds included for each group of 10 to18 environmental samples analyzed at the NWQL. The low-concentration and high-concentration reagent spike experiments, by contrast, represent a one-time assessment of method performance. For each spike experiment, mean recoveries ranging from 60 to 130 percent indicate low bias, and relative standard deviations (RSDs) less than ( Of the compounds included in the filtered method, 21 had mean recoveries ranging from 63 to 129 percent for the low-level and high-level surface-water spikes, and had low ()132 percent]. For wastewater spikes, 24 of the compounds included in the filtered method had recoveries ranging from 61 to 130 percent for the low-level and high-level spikes. RSDs were 130 percent) or variable recoveries (RSDs >30 percent) for low-level wastewater spikes, or low recoveries ( Of the compounds included in the unfiltered method, 17 had mean spike recoveries ranging from 74

  1. Analysis of hemoglobin adducts of benzene oxide by gas chromatography-mass spectrometry.

    PubMed

    Yeowell-O'Connell, K; McDonald, T A; Rappaport, S M

    1996-05-15

    A method is reported for measuring cysteinyl adducts of the benzene metabolite benzene oxide (BO) with hemoglobin (Hb) in blood from humans or rodents exposed to benzene. After reacting the purified, dried protein with trifluoroacetic anhydride and methanesulfonic acid, the resulting phenyltrifluorothioacetate is extracted, washed, and detected by GC-MS in the negative-ion chemical ionization mode. The analysis of Hb adducts of BO from rats dosed with 50-400 mg/kg [13C6]benzene via this method resulted in values which were generally consistent, though slightly lower, than those obtained using an established method. However, while 3 weeks were required to process the samples by the former method, only 2 days were needed with the new procedure. This new method should, therefore, prove to be reliable and convenient for the rapid quantitation of cysteine-bound Hb adducts of BO. PMID:8660536

  2. Analysis of the thermal reaction products of para polyphenylene by combined gas chromatography-mass spectrometry

    NASA Technical Reports Server (NTRS)

    Fewell, L. L.

    1976-01-01

    Analysis of the volatiles and sublimate produced when para-polyphenylene is pyrolyzed to constant weight under vacuum in the temperature range from 380 to 1000 C indicates that the polymer undergoes thermal degradation in two stages. The first stage involved dehydrohalogenation, which is essentially a curing reaction that produces crosslinking between polyphenylene chains resulting from the loss of chlorine from the polymer in the form of hydrogen chloride. The second stage of the thermal degradation is dehydrogenation because hydrogen is the major volatile species. Increasing amounts of polycyclic aromatic hydrocarbons (phenanthrene and 9, 10 benzphenanthrene) in the sublimate, concomitant with increasing C/H ratios of the polymeric residue with pyrolysis temperature, is consistent with the buildup of polynuclear structures in the polymer matrix.

  3. iMatch: a retention index tool for analysis of gas chromatography-mass spectrometry data.

    PubMed

    Zhang, Jun; Fang, Aiqin; Wang, Bing; Kim, Seong Ho; Bogdanov, Bogdan; Zhou, Zhanxiang; McClain, Craig; Zhang, Xiang

    2011-09-16

    A method was developed to employ National Institute of Standards and Technology (NIST) 2008 retention index database information for molecular retention matching via constructing a set of empirical distribution functions (DFs) of the absolute retention index deviation to its mean value. The effects of different experimental parameters on the molecules' retention indices were first assessed. The column class, the column type, and the data type have significant effects on the retention index values acquired on capillary columns. However, the normal alkane retention index (I(norm)) with the ramp condition is similar to the linear retention index (I(T)), while the I(norm) with the isothermal condition is similar to the Kováts retention index (I). As for the I(norm) with the complex condition, these data should be treated as an additional group, because the mean I(norm) value of the polar column is significantly different from the I(T). Based on this analysis, nine DFs were generated from the grouped retention index data. The DF information was further implemented into a software program called iMatch. The performance of iMatch was evaluated using experimental data of a mixture of standards and metabolite extract of rat plasma with spiked-in standards. About 19% of the molecules identified by ChromaTOF were filtered out by iMatch from the identification list of electron ionization (EI) mass spectral matching, while all of the spiked-in standards were preserved. The analysis results demonstrate that using the retention index values, via constructing a set of DFs, can improve the spectral matching-based identifications by reducing a significant portion of false-positives. PMID:21813131

  4. Quantitative analysis of alachlor protein adducts by gas chromatography-mass spectrometry.

    PubMed

    Lambert, G R; Padgett, W T; George, M H; Kitchin, K T; Nesnow, S

    1999-03-15

    This study examined the potential use of hemoglobin (Hb)- and serum-protein adducts of alachlor as potential biomarkers of alachlor exposure, a genotoxic and carcinogenic herbicide. The method developed was based on the observation that cleavage of S-cysteinyl alachlor-protein adducts by methanesulfonic acid gave the rearrangement product 3-(2',6'-diethylphenyl)-1, 3-thiazolidine-4-one (TZO). The structure of TZO was confirmed by mass spectroscopy, NMR spectroscopy, and independent synthesis. In the assay, treatment of alachlor-cysteinyl protein adducts by methanesulfonic acid was followed by extraction and analysis. TZO was detected and quantitated by electron-impact GC/MS in the single ion-monitoring mode. [ring-13C6]Alachlor-N-acetylcysteine was added as an internal standard prior to treatment and was converted to [ring-13C6]TZO, allowing response factors to be used to quantitate TZO concentrations. Incubations of alachlor (0-1000 microM) with human albumin and bovine serum albumin (BSA) resulted in linear adduct formation with both proteins. Maximal adduction levels of 613-1130 pmol alachlor-albumin adducts/mg protein were observed, with BSA binding close to twice that of human albumin. A linear concentration response of alachlor-Hb adducts was observed when whole blood from female CD rats was incubated with alachlor in vitro at concentrations up to 300 microM. Maximal binding was 1860 pmol alachlor-Hb adducts/mg globin. Male CD rats treated with alachlor at 150 mg/kg body wt/day ip for 0, 1, 2, and 3 days were sacrificed 4 days after final dosing. A maximal binding of 2250 pmol alachlor-Hb adducts/mg globin was observed. This assay provides a new approach for biomonitoring alachlor levels in experimental animals and has the potential for use in humans. PMID:10075819

  5. Chemical Composition of Latent Fingerprints by Gas Chromatography-Mass Spectrometry

    ERIC Educational Resources Information Center

    Hartzell-Baguley, Brittany; Hipp, Rachael E.; Morgan, Neal R.; Morgan, Stephen L.

    2007-01-01

    An experiment in which gas chromatography-mass spectrometry (GC-MS) is used for latent fingerprint extraction and analysis on glass beads or glass slides is conducted. The results determine that the fingerprint residues are gender dependent.

  6. Determination of ink photoinitiators in packaged beverages by gas chromatography–mass spectrometry and liquid chromatography–mass spectrometry

    Microsoft Academic Search

    Gianni Sagratini; Giovanni Caprioli; Gloria Cristalli; Dario Giardiná; Massimo Ricciutelli; Rosaria Volpini; Yanting Zuo; Sauro Vittori

    2008-01-01

    A new analytical method, using gas chromatography–mass spectrometry (GC\\/MS) and liquid chromatography–mass spectrometry (LC\\/MS) techniques, was developed for the determination in packaged food beverages of five ink photoinitiator residues: 2-isopropylthioxanthone (ITX), benzophenone, 2-ethylhexyl-4-dimethylaminobenzoate (EHDAB), 1-hydroxycyclohexyl-1-phenyl ketone (IRGACURE 184) and ethyl-4-dimethylaminobenzoate (EDAB). Samples were extracted from selected beverages (milk, fruit juices and wine) and relative packagings, using n-hexane and dichloromethane, respectively,

  7. Disposable pipette extraction for the analysis of pesticides in fruit and vegetables using gas chromatography/mass spectrometry.

    PubMed

    Guan, Hongxia; Brewer, William E; Garris, Sherry T; Morgan, Stephen L

    2010-03-19

    Organochlorine, organophosphate pesticides and fungicides in fruits and vegetables were analyzed using disposable pipette extraction (DPX) followed by gas chromatography-mass spectrometry-selective ion monitoring (GC/MS-SIM). The intrinsic rapid mixing capabilities of DPX result in fast and efficient extractions, and eluates are concentrated by using minimal elution solvent volumes rather than solvent evaporation methods. Matrix-matched calibrations were performed with reversed phase mechanisms (DPX-RP), and the limits of detection (LOD) were determined to be lower than 0.1 microg/mL for all targeted pesticides in carrot and orange sample matrices. Coefficients of determination (r(2)) were greater than 0.995 for most studied pesticides. DPX-RP exhibited recoveries between 72 and 116% for nonpolar and slightly polar pesticides (logP>2) with most of the recoveries over 88%. Only very polar pesticides (e.g., acephate, mathamidophos) were not extracted well using DPX-RP. PMID:20144461

  8. Pressurized liquid extraction-gas chromatography-mass spectrometry analysis of fragrance allergens, musks, phthalates and preservatives in baby wipes.

    PubMed

    Celeiro, Maria; Lamas, J Pablo; Garcia-Jares, Carmen; Llompart, Maria

    2015-03-01

    Baby wipes and wet toilet paper are specific hygiene care daily products used on newborn and children skin. These products may contain complexes mixtures of harmful chemicals. A method based on pressurized liquid extraction (PLE) followed by gas chromatography-mass spectrometry (GC-MS) has been developed for the simultaneous determination of sixty-five chemical compounds (fragrance allergens, preservatives, musks, and phthalates) in wipes and wet toilet paper for children. These compounds are legislated in Europe according Regulation EC No 1223/2009, being twelve of them banned for their use in cosmetics, and one of them, 3-iodo-2-propynyl butylcarbamate (IPBC), is banned in products intended for children under 3 years. Also, propyl-, and butylparaben will be prohibited in leave-on cosmetic products designed for application on the nappy area of children under 3 years from April 2015. PLE is a fast, simple, easily automated technique, which permits to integrate a clean-up step during the extraction process reducing analysis time and stages. The proposed PLE-based procedure was optimized on real non-spiked baby wipe samples by means of experimental design to study the influence on extraction of parameters such as extraction solvent, temperature, extraction time, and sorbent type. Under the selected conditions, the method was validated showing satisfactory linearity, and intra-day, and inter-day precision. Recoveries were between 80-115% for most of the compounds with relative standard deviations (RSD) lower than 15%. Finally, twenty real samples were analyzed. Thirty-six of the target analytes were detected, highlighting the presence of phenoxyethanol in all analyzed samples at high concentration levels (up to 0.8%, 800?gg(-1)). Methyl paraben (MeP), and ethyl paraben (EtP) were found in 40-50% of the samples, and the recently banned isobutyl paraben (iBuP) and isopropyl paraben (iPrP), were detected in one and seven samples, respectively, at concentrations between 0.093 and 247?gg(-1). In the case of phthalates, the forbidden phthalates dibutyl phtalate (DBP) and di(2-ethylhexyl)phthalate (DEHP) were also found in thirteen samples at low levels. All the samples contained fragrance allergens in many cases at high levels (up to 2400?gg(-1)) and three musks were detected in the samples. Excluding the banned compounds, all samples complied with the concentration limits established by the European Regulation although 25% of them did not fulfill the labeling requirements for fragrance allergens. PMID:25662066

  9. Studies on the metabolism and the toxicological analysis of the nootropic drug fipexide in rat urine using gas chromatography–mass spectrometry

    Microsoft Academic Search

    Roland F. Staack; Hans H. Maurer

    2004-01-01

    Qualitative studies are described on the metabolism and the toxicological analysis of the nootropic fipexide (FIP) in rat urine using gas chromatography–mass spectrometry (GC–MS). FIP was extensively metabolized to 1-(3,4-methylenedioxybenzyl)piperazine (MDBP), 4-chlorophenoxyacetic acid, 1-[2-(4-chlorophenoxy)acetyl]piperazine, N-(4-hydroxy-3-methoxy-benzyl)piperazine, piperazine, N-(3,4-methylenedioxybenzyl)ethylenediamine, and N-[2-(4-chlorophenoxy)acetyl]ethylenediamine. The authors’ systematic toxicological analysis (STA) procedure using full-scan GC–MS after acid hydrolysis of one urine aliquot, liquid-liquid extraction and acetylation

  10. Analysis of volatile compounds emitted by filamentous fungi using solid-phase microextraction-gas chromatography/mass spectrometry.

    PubMed

    Roze, Ludmila V; Beaudry, Randolph M; Linz, John E

    2012-01-01

    Here, we describe a solid-phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS) analytical approach that identifies and analyzes volatile compounds in the headspace above a live fungal culture. This approach is a sensitive, solvent-free, robust technique; most importantly from a practical standpoint, this approach is noninvasive and requires minimal sample handling. Aliquots of liquid fungal cultures are placed into vials equipped with inert septa and equilibrated at a constant temperature, and headspace gases are sampled using an SPME fiber inserted through the septum into the headspace above the fungal culture for a standardized period of time. The outer polymer coating of a fused silica fiber absorbs volatiles from the headspace; the volatiles are then desorbed in the hot GC inlet and chromatographed in the usual manner. The separated compounds are subsequently identified by mass spectrometry. All steps in volatile profiling of a single sample from volatile sorption on a fiber to obtaining a list of volatiles can take as little as 15 min or can be extended to several hours if longer sorption is required for compounds present at very low levels and/or have low rates of diffusion. PMID:23065613

  11. Titan's Organic Aerosols : Molecular Composition And Structure Inferred From Systematic Pyrolysis Gas Chromatography Mass Spectrometry Analysis of Analogues

    NASA Astrophysics Data System (ADS)

    Morisson, Marietta; Szopa, Cyril; Buch, Arnaud; Carrasco, Nathalie; Gautier, Thomas

    2015-04-01

    In spite of numerous studies carried out to characterize the chemical composition of laboratory analogues of Titan aerosols (tholins), their molecular composition as well as their structuration are still little known. If Pyrolysis gas chromatography mass spectrometry (Pyr-GCMS) has been used for years to give clues about this composition, the highly disparate results obtained show that they can be attributed to the analytical conditions used, to differences in the nature of the analogues studied, or both. In order to have a better description of Titan's tholins molecular composition, we led a systematic analysis of these materials by pyr-GCMS, exploring the analytical parameters to estimate the biases this technique can induce. With this aim, we used the PAMPRE experiment, a capacitively coupled RF cold plasma reactor (Szopa et al. 2006), to synthetize tholins with 2%, 5% and 10% of CH4 in N2. The three samples were systematically pyrolyzed in the temperature range 200-600°C with a 100°C step. The evolved gases were then injected into a GC-MS device for molecular identification. This systematic pyr-GC-MS analysis had two major objectives: (i) optimizing all the analytical parameters for the detection of a wide range of compounds and thus a characterization of the tholins composition as comprehensive as possible, and (ii) highlighting the role of the CH4 ratio on the tholins molecular structure. About a hundred of molecules have been identified in the pyrolysis products. Although an identical major pattern of nitriles and ethylene appears clearly for the three samples, some discriminant signatures were highlighted. The samples mainly differ by the number of released compounds. The results show especially an increase in the hydrocarbonaceous chains when the CH4 ratio increases. At the opposite, the formation of poly-nitrogenous compounds seems to be easier for lower CH4 ratios. We also performed a semi-quantitative study on the best represented chemical family in our chromatograms - namely nitriles: the existence of a relation between the quantity of a released compound and its molecular mass is consistent with the quantification of nitriles in the PAMPRE gas phase done by Gautier et al., 2011. Moreover, numerous species are present both in tholins and in the gas phase. That allowed us to make out potential precursors of the solid organic particles. From all these results, we conclude that the optimal pyrolysis temperature for a GC-MS analysis of our tholins is 600°C. This temperature choice results from the best compromise between the number of released compounds, the quality of the signal and the appearance of pyrolysis artefacts. Lastly, thanks to a review of pyr-GCMS studies carried out on Titan tholins since the first work of Khare et al. (1981), we compared all the previous analyses between them and with our own results in order to better understand the differences. References B. N. Khare et al., Icarus, vol. 48, no. 2, pp. 290-297, Nov. 1981. C. Szopa et al., Planet. Space Sci., vol. 54, no. 4, pp. 394-404, Apr. 2006. T. Gautier et al., Icarus, vol. 213, no. 2, pp. 625-635, Jun. 2011.

  12. Convenient analysis of vitamin D in cheese and other food matrixes by liquid chromatography/mass spectrometry.

    PubMed

    Dimartino, Gianluca

    2007-01-01

    A convenient method is presented for determination of vitamin D in natural cheese, processed cheese, milk, cereals, noncarbonated soft drinks, and juice by liquid chromatography/ mass spectrometry (LC/MS). Samples were saponified, extracted, evaporated, redissolved in acetonitrile, and injected into an LC-atmospheric pressure chemical ionization-MS system with no preparative chromatographic steps. Vitamin D was determined by selected ion monitoring. MS response was linear for vitamin D3 and its internal standard vitamin D2, and overall average recoveries ranged from 98 to 105%. A blending experiment in which shredded vitamin D3-fortified cheddar was mixed with control nonfortified cheddar showed linearity. The limit of detection for vitamin D was 1.3 ng and the limit of quantitation was 3 ng. The method gave good accuracy and precision, with a standard deviation of 9.5 and relative standard deviation of 6.7%. Results for vitamin D3 obtained with this method for different food matrixes, at different levels, were in agreement with those obtained with the reference LC/UV method currently used by many laboratories and derived from AOAC Official Method 982.29. PMID:17955977

  13. Thin layer chromatography/mass spectrometry.

    PubMed

    Cheng, Sy-Chyi; Huang, Min-Zong; Shiea, Jentaie

    2011-05-13

    Thin layer chromatography (TLC)--a simple, cost-effective, and easy-to-operate planar chromatographic technique--has been used in general chemistry laboratories for several decades to routinely separate chemical and biochemical compounds. Traditionally, chemical and optical methods are employed to visualize the analyte spots on the TLC plate. Because direct identification and structural characterization of the analytes on the TLC plate through these methods are not possible, there has been long-held interest in the development of interfaces that allow TLC to be combined with mass spectrometry (MS)--one of the most efficient analytical tools for structural elucidation. So far, many different TLC-MS techniques have been reported in the literature; some are commercially available. According to differences in their operational processes, the existing TLC-MS systems can be classified into two categories: (i) indirect mass spectrometric analyses, performed by scraping, extracting, purifying, and concentrating the analyte from the TLC plate and then directing it into the mass spectrometer's ion source for further analysis; (ii) direct mass spectrometric analyses, where the analyte on the TLC plate is characterized directly through mass spectrometry without the need for scraping, extraction, or concentration processes. Conventionally, direct TLC-MS analysis is performed under vacuum, but the development of ambient mass spectrometry has allowed analytes on TLC plates to be characterized under atmospheric pressure. Thus, TLC-MS techniques can also be classified into two other categories according to the working environment of the ion source: vacuum-based TLC-MS or ambient TLC-MS. This review article describes the state of the art of TLC-MS techniques used for indirect and direct characterization of analytes on the surfaces of TLC plates. PMID:21334632

  14. Pathway Confirmation and Flux Analysis of Central Metabolic Pathways in Desulfovibrio vulgaris Hildenborough using Gas Chromatography-Mass Spectrometry and Fourier Transform-Ion Cyclotron Resonance Mass Spectrometry? †

    PubMed Central

    Tang, Yinjie; Pingitore, Francesco; Mukhopadhyay, Aindrila; Phan, Richard; Hazen, Terry C.; Keasling, Jay D.

    2007-01-01

    Flux distribution in central metabolic pathways of Desulfovibrio vulgaris Hildenborough was examined using 13C tracer experiments. Consistent with the current genome annotation and independent evidence from enzyme activity assays, the isotopomer results from both gas chromatography-mass spectrometry (GC-MS) and Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) indicate the lack of an oxidatively functional tricarboxylic acid (TCA) cycle and an incomplete pentose phosphate pathway. Results from this study suggest that fluxes through both pathways are limited to biosynthesis. The data also indicate that >80% of the lactate was converted to acetate and that the reactions involved are the primary route of energy production [NAD(P)H and ATP production]. Independently of the TCA cycle, direct cleavage of acetyl coenzyme A to CO and 5,10-methyl tetrahydrofuran also leads to production of NADH and ATP. Although the genome annotation implicates a ferredoxin-dependent oxoglutarate synthase, isotopic evidence does not support flux through this reaction in either the oxidative or the reductive mode; therefore, the TCA cycle is incomplete. FT-ICR MS was used to locate the labeled carbon distribution in aspartate and glutamate and confirmed the presence of an atypical enzyme for citrate formation suggested in previous reports [the citrate synthesized by this enzyme is the isotopic antipode of the citrate synthesized by the (S)-citrate synthase]. These findings enable a better understanding of the relation between genome annotation and actual metabolic pathways in D. vulgaris and also demonstrate that FT-ICR MS is a powerful tool for isotopomer analysis, overcoming the problems with both GC-MS and nuclear magnetic resonance spectroscopy. PMID:17114264

  15. Analysis of quazepam and its metabolites in human urine by gas chromatography-mass spectrometry: application to a forensic case.

    PubMed

    Terada, Masaru; Shinozuka, Tatsuo; Hasegawa, Chika; Tanaka, Einosuke; Hayashida, Makiko; Ohno, Youkichi; Kurosaki, Kunihiko

    2013-04-10

    A sensitive method for the simultaneous determination of quazepam and two of its metabolites, 2-oxoquazepam and 3-hydroxy-2-oxoquazepam, in human urine was developed using gas chromatography-mass spectrometry (GC/MS) with an Rtx-5MS capillary column. The quazepam and its metabolites were extracted from human urine using a simple solid-phase extraction Oasis(®) HLB cartridge column, and the 3-hydroxy-2-oxoquazepam was derivatised using BSTFA/1%TMCS and pyridine at 60 °C for 30 min. The mass spectrometric detection of the analytes was performed in the full scan mode, m/z 60-480, and selected ion monitoring (SIM) mode, m/z 386, for quazepam; m/z 342, for 2-oxoquazepam; m/z 429, for 3-hydroxy-2-oxoquazepam-TMS; and m/z 284, for alprazolam-d5 (internal standard), by electron ionization. The calibration curves of quazepam and its metabolites in urine showed good linearity in the concentration range of 2.5-500 ng/0.2 ml of urine. The average recoveries of quazepam and its metabolites from 0.2 ml of urine containing 500 ng and 50 ng of each drug were 71-83% and 88-90%, respectively. The limits of detection of quazepam, 2-oxoquazepam and 3-hydroxy-2-quazepam in urine by the selected ion monitoring mode were 0.096-0.37 ng/ml. This method would be applicable to other forensic biological materials containing low concentrations of quazepam and its metabolites. PMID:23290298

  16. Determination of ink photoinitiators in packaged beverages by gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry.

    PubMed

    Sagratini, Gianni; Caprioli, Giovanni; Cristalli, Gloria; Giardiná, Dario; Ricciutelli, Massimo; Volpini, Rosaria; Zuo, Yanting; Vittori, Sauro

    2008-06-20

    A new analytical method, using gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-mass spectrometry (LC/MS) techniques, was developed for the determination in packaged food beverages of five ink photoinitiator residues: 2-isopropylthioxanthone (ITX), benzophenone, 2-ethylhexyl-4-dimethylaminobenzoate (EHDAB), 1-hydroxycyclohexyl-1-phenyl ketone (IRGACURE 184) and ethyl-4-dimethylaminobenzoate (EDAB). Samples were extracted from selected beverages (milk, fruit juices and wine) and relative packagings, using n-hexane and dichloromethane, respectively, purified on solid-phase extraction (SPE) silica gel cartridges, and then analyzed in GC/MS and LC/MS. The recovery percentages, obtained spiking the beverage samples at concentrations of 4 and 10 microgl(-1) with a standard mixture of photoinitiators, were in the range 42-108% (milk), 50-84% (wine), and 48-109% (fruit juices). The repeatability of the method was assessed in all cases by the % of correlation value, that was lower than 19%. The lowest limits of detection (LODs) and limits of quantification (LOQs), obtained using GC/MS, were in the range 0.2-1 and 1-5 microgl(-1), respectively. The method was applied to the analysis of forty packaged food beverages (milk, fruit juices and wine samples). The most significant contamination was that of benzophenone, found in all samples in a concentration range of 5-217mugl(-1). Its presence was confirmed by an LC/Atmospheric-Pressure PhotoIonization (APPI)/MS/MS analysis. The photoinitiator (EHDAB) was found in eleven out of forty beverages in a concentration range of 0.13-0.8 microgl(-1). Less important was the ITX contamination, found in three out of forty samples in a range 0.2-0.24 microgl(-1). The work proposes a new method to analyze ink photoinitiator residues in polycoupled carton packaging and in contained food beverages. PMID:18486139

  17. Preparation of durable graphene-bonded titanium fibers for efficient microextraction of phthalates from aqueous matrices and analysis with gas chromatography-mass spectrometry.

    PubMed

    Zhang, Bo-Tao; Li, Hai-Fang; Zheng, Xiaoxia; Teng, Yanguo; Liu, Yan; Lin, Jin-Ming

    2014-11-28

    A solid-phase microextraction fiber (SPME) was synthesized for pre-concentration of 15 phthalates from aqueous samples. Graphene oxide was immobilized on Ti wire with titanol groups using a cross-linking agent and subsequently reduced to yield a folded and wrinkled graphene coating. This graphene-Ti fiber demonstrated durable mechanical robustness and enhanced stability for more than 200 extraction cycles due to the Ti substrate and chemical bond. The extraction efficiencies reached highest when the graphene layers were four and their performances were superior to commercial SPME fibers. The prepared fiber was used for pre-concentration of phthalates from aqueous samples by direct immersion extraction and thermal desorption for gas chromatography-mass spectrometry analysis. The method was utilized for the simultaneous analysis of 15 phthalates with satisfactory recoveries in the range of 82.8-97.8% for bottled water and 73.3-102.0% for intravenous drips in plastic packaging. PMID:25454125

  18. Comparative analysis of Pu-erh and Fuzhuan teas by fully automatic headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry and chemometric methods.

    PubMed

    Lv, Shidong; Wu, Yuanshuang; Li, Changwen; Xu, Yongquan; Liu, Lun; Meng, Qingxiong

    2014-02-26

    Thirteen Pu-erh teas and 13 Fuzhuan teas obtained from two different production areas in China were profiled using fully automatic headspace solid-phase microextraction (HS-SPME)/gas chromatography-mass spectrometry (GC-MS) coupled with chemometric methods. A total of 93 aroma components were identified in 26 dark teas; among them, methoxyphenolic compounds (31.77%) were the most abundant components in Pu-erh teas, whereas ketone compounds were the most abundant components (25.42%) in Fuzhuan teas. Cluster analysis (CA) and principal component analysis (PCA) showed that these two types of dark teas could be clearly distinguished according to their chemical characteristics. This study suggested that the proposed strategy could provide a feasible and rapid technique to differentiate dark teas with similar morphological characteristics from different production areas by their volatile composition and relative content. PMID:24512533

  19. Gas chromatography-mass spectrometry and high-performance liquid chromotagraphy analysis of the drug absorption characteristics in the buccal mucosa via a circulating device

    PubMed Central

    WU, XIN; LI, YUBO; XU, DAOQING; ZHOU, HONG; WANG, JINLEI; GUO, XUEJUN; ZHANG, YANJUN

    2015-01-01

    The aim of the present study was to investigate the characteristics of Su Xiao Jiu Xin dripping pill absorption in the buccal mucosa of healthy volunteers. This pill is a traditional Chinese medicine that is widely used as an emergency treatment for cardiovascular and cerebrovascular diseases. It is sublingually administered and can be absorbed in the buccal mucosa. In the present study, a method was developed to investigate the absorption characteristics in the buccal mucosa of healthy volunteers via a circulating device by gas chromatography-mass spectrometry and high-performance liquid chromatography. The five main efficacy components associated with cardiovascular and cerebrovascular diseases, which are borneol, isoborneol, ligustilide, n-butylphthalide and ferulic acid, were detected and rapidly absorbed. Among these components, four exhibited good absorption, thus confirming that the method developed is efficient for analysis of the absoption characteristics. PMID:25469246

  20. On-line ion-pair solid-phase extraction-liquid chromatography-mass spectrometry for the analysis of quaternary ammonium herbicides.

    PubMed

    Castro, R; Moyano, E; Galceran, M T

    2000-02-11

    An ion-pair on-line solid-phase extraction procedure using C8 extraction disks, suitable for liquid chromatography-mass spectrometry analysis is developed to determine quaternary ammonium herbicides (quats) in water samples. The separation of these compounds was performed using ion-pair chromatography with heptafluorobutyric acid (15 mM, pH 3.3) and acetonitrile gradient elution. Detection was carried out using a quadrupole mass spectrometer. Water sample volumes up to 50 ml can be preconcentrated with recoveries higher than 70%. Good precision and accuracy (day-to-day and run-to-run) were obtained and the detection limits ranged from 6 to 85 ng l(-1). The proposed on-line ion-pair solid-phase method enables compliance with European Community directives for drinking waters (100 ng l(-1)). PMID:10720257

  1. Triclosan and methyl-triclosan monitoring study in the northeast of Spain using a magnetic particle enzyme immunoassay and confirmatory analysis by gas chromatography mass spectrometry

    NASA Astrophysics Data System (ADS)

    Kantiani, Lina; Farré, Marinella; Asperger, Danijela; Rubio, Fernando; González, Susana; López de Alda, Maria J.; Petrovi?, Mira; Shelver, Weilin L.; Barceló, Damià

    2008-10-01

    SummaryFor the first time, the occurrence of triclosan and its metabolite methyl-triclosan was investigated in a typical Mediterranean area using a two-step methodology based on screening using a magnetic particle immunoassay (IA) and confirmatory analysis by solid phase extraction (SPE) followed by gas chromatography-mass spectrometry (GC-MS). In this study, 95 environmental samples were analyzed. A commercial immunoassay was assessed for use in the different types of water selected for this study. A large monitoring study was performed on the influent and the effluent of eight wastewater treatment plants (WWTPs), water samples from Ebro and Llobregat rivers, and drinking water. All wastewater samples tested in this study (influents and effluents) showed the presence of triclosan, with concentrations for raw influents being high (10 ?g/L as average value). The percentages of triclosan removal for the WWTPs were evaluated (30-70%) along the different treatment processes showing that the best removal rates were obtained by the processes equipped with membrane bioreactors (MBRs). However, important concentrations of triclosan were detected even after treatment by MBRs. The presence of this biocide was confirmed in 50% of the river samples analyzed. Twenty two drinking water samples from the Barcelona city area were investigated, and in this case no triclosan was detected. Due to its properties and the widespread usage of triclosan, there is a need for monitoring and controlling the amounts present in wastewater effluents, river water, drinking water catchments areas, and drinking water. To this end, we present a feasible methodology using a magnetic particle-based immunoassay as a screening, followed by confirmatory analysis using solid phase extraction-gas chromatography-mass spectrometry (SPE-GC-MS).

  2. Global analysis of multiple gas chromatography–mass spectrometry (GC\\/MS) data sets: A method for resolution of co-eluting components with comparison to MCR-ALS

    Microsoft Academic Search

    Ivo H. M. van Stokkum; Katharine M. Mullen; Velitchka V. Mihaleva

    2009-01-01

    Global analysis has been applied to resolve components in multiple gas chromatography–mass spectrometry (GC\\/MS) data sets. Global analysis methodology is based upon a parametrized model of the observed data, including random (and possibly also systematic) errors. Each elution profile is described as a function of a small number of parameters. We successfully based the description of elution profiles on an

  3. NHEXAS PHASE I REGION 5 STUDY--STANDARD OPERATING PROCEDURE--ANALYSIS OF VOLATILE ORGANIC COMPOUNDS FROM CHARCOAL BADGES BY GAS CHROMATOGRAPHY/MASS SPECTROMETRY (RTI/ACS-AP-209-112)

    EPA Science Inventory

    This protocol provides guidelines for determining volatile organic hydrocarbons (VOCs) in air samples by gas chromatography/mass spectrometry (GC/MS). This method is for the analysis of VOCs in air by GC/MS in the selected ion monitoring mode (SIM). Charcoal badge samplers are ex...

  4. Assessment of a new method for the analysis of decomposition gases of polymers by a combining thermogravimetric solid-phase extraction and thermal desorption gas chromatography mass spectrometry.

    PubMed

    Duemichen, E; Braun, U; Senz, R; Fabian, G; Sturm, H

    2014-08-01

    For analysis of the gaseous thermal decomposition products of polymers, the common techniques are thermogravimetry, combined with Fourier transformed infrared spectroscopy (TGA-FTIR) and mass spectrometry (TGA-MS). These methods offer a simple approach to the decomposition mechanism, especially for small decomposition molecules. Complex spectra of gaseous mixtures are very often hard to identify because of overlapping signals. In this paper a new method is described to adsorb the decomposition products during controlled conditions in TGA on solid-phase extraction (SPE) material: twisters. Subsequently the twisters were analysed with thermal desorption gas chromatography mass spectrometry (TDS-GC-MS), which allows the decomposition products to be separated and identified using an MS library. The thermoplastics polyamide 66 (PA 66) and polybutylene terephthalate (PBT) were used as example polymers. The influence of the sample mass and of the purge gas flow during the decomposition process was investigated in TGA. The advantages and limitations of the method were presented in comparison to the common analysis techniques, TGA-FTIR and TGA-MS. PMID:24929909

  5. Independent evaluation of a commercial deconvolution reporting software for gas chromatography mass spectrometry analysis of pesticide residues in fruits and vegetables

    Microsoft Academic Search

    Hans Ragnar Norli; Agnethe Christiansen; Børge Holen

    2010-01-01

    The gas chromatography mass spectrometry (GC–MS) deconvolution reporting software (DRS) from Agilent Technologies has been evaluated for its ability as a screening tool to detect a large number of pesticides in incurred and fortified samples extracted with acetone\\/dichloromethane\\/light petroleum (Mini-Luke method). The detection of pesticides is based on fixed retention times using retention time locking (RTL) and full scan mass

  6. Molecular analysis of sulphur-rich brown coals by flash pyrolysis-gas chromatography-mass spectrometry: The type III-S kerogen

    Microsoft Academic Search

    Jaap S. Sinninghe Damsté; F. X. C. de Las Heras; J. W. de Leeuw

    1992-01-01

    The molecular composition of five brown coals from three different basins (Maestrazgo, Mequinenza and Rubielos) in Spain was investigated by flash pyrolysis-gas chromatography and flash pyrolysis-gas chromatography-mass spectrometry. In these techniques, the macromolecular material is thermally degraded in an inert atmosphere and the compounds formed are on-line separated, identified and quantified. This information provided insight into the macromolecular structure of

  7. An experimental design approach for optimizing polycyclic aromatic hydrocarbon analysis in contaminated soil by pyrolyser-gas chromatography-mass spectrometry

    Microsoft Academic Search

    S. Buco; M. Moragues; M. Sergent; P. Doumenq; G. Mille

    2007-01-01

    Pyrolyser-gas chromatography-mass spectrometry was used to analyze polycyclic aromatic hydrocarbons in contaminated soil without preliminary extraction. Experimental research methodology was used to obtain optimal performance of the system. After determination of the main factors (desorption time, Curie point temperature, carrier gas flow), modeling was done using a Box–Behnken matrix. Study of the response surface led to factor values that optimize

  8. Characterization of volatile components of Iranian saffron using factorial-based response surface modeling of ultrasonic extraction combined with gas chromatography–mass spectrometry analysis

    Microsoft Academic Search

    Mehdi Jalali-Heravi; Hadi Parastar; Heshmatollah Ebrahimi-Najafabadi

    2009-01-01

    The volatile components of Iranian saffron were extracted using ultrasonic solvent extraction (USE) technique and then were separated and detected by gas chromatography–mass spectrometry (GC–MS). Variables affecting the extraction procedure were screened by using a 25?1 fractional factorial design and among them; sample amount, solvent volume, solvent ratio and extraction time were optimized by applying a rotatable central composite design

  9. Miniaturized hollow fiber assisted liquid-phase microextraction with in situ derivatization and gas chromatography–mass spectrometry for analysis of bisphenol A in human urine sample

    Microsoft Academic Search

    Migaku Kawaguchi; Rie Ito; Noriya Okanouchi; Koichi Saito; Hiroyuki Nakazawa

    2008-01-01

    A new method that involves miniaturized hollow fiber assisted liquid-phase microextraction (HF-LPME) with in situ derivatization and gas chromatography–mass spectrometry (GC–MS) is described for the determination of trace amounts of bisphenol A (BPA) in human urine samples. The detection limit and the quantification limit of BPA in human urine sample are 0.02 and 0.1ngml?1 (ppb), respectively. The calibration curve for

  10. Gas chromatography–mass spectrometry following microwave distillation and headspace solid-phase microextraction for fast analysis of essential oil in dry traditional Chinese medicine

    Microsoft Academic Search

    Ning Li; Chunhui Deng; Yan Li; Hao Ye; Xiangmin Zhang

    2006-01-01

    In this paper, a novel method based on gas chromatography–mass spectrometry (GC–MS) following microwave distillation-headspace solid-phase microextraction (MD-HS-SPME) was developed for the determination of essential oil in dry traditional Chinese medicine (TCM). TCM is dried before being preserved and used, there is too little water to absorb microwave energy and heat the TCM samples. In the work, carbonyl iron powders

  11. High-Throughput and Comprehensive Lipidomic Analysis Using Ultrahigh-Performance Supercritical Fluid Chromatography-Mass Spectrometry.

    PubMed

    Lísa, Miroslav; Hol?apek, Michal

    2015-07-21

    New analytical approach for high-throughput and comprehensive lipidomic analysis of biological samples using ultrahigh-performance supercritical fluid chromatography (UHPSFC) with electrospray ionization-mass spectrometry (ESI-MS) is presented in this work as an alternative approach to established shotgun MS or high-performance liquid chromatography-MS. The lipid class separation is performed by UHPSFC method based on 1.7 ?m particle-bridged ethylene hybrid silica column with a gradient of methanol-water-ammonium acetate mixture as a modifier. All parameters of UHPSFC conditions are carefully optimized and their influence on the chromatographic behavior of lipids is discussed. The final UHPSFC/ESI-MS method enables a fast separation of 30 nonpolar and polar lipid classes within 6 min analysis covering 6 main lipid categories including fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, sterols, and prenols. Individual lipid species within lipid classes are identified based on positive and negative-ion full-scan and tandem mass spectra measured with high mass accuracy and high resolving power. Developed UHPSFC/ESI-MS method is applied for the analysis of porcine brain extract as a complex lipidomic sample, where 24 lipid classes containing 436 lipid species are identified. The method is validated for the quantitative analysis of lipid species in biological tissues using internal standards for each lipid class. This high-throughput, comprehensive and accurate UHPSFC/ESI-MS method is suitable for the lipidomic analysis of large sample sets in the clinical research. PMID:26095628

  12. Headspace in-tube extraction gas chromatography-mass spectrometry for the analysis of hydroxylic methyl-derivatized and volatile organic compounds in blood and urine.

    PubMed

    Rasanen, Ilpo; Viinamäki, Jenni; Vuori, Erkki; Ojanperä, Ilkka

    2010-04-01

    A novel headspace in-tube extraction gas chromatography-mass spectrometry (ITEX-GC-MS) approach was developed for broad-scale analysis of low molecular weight organic compounds in blood and/or urine. One sample was analyzed following in-vial derivatization with dimethyl sulfate for ethylene glycol (EG), glycolic acid (GA), formic acid (FA), other hydroxylic compounds, and another sample for underivatized volatile organic compounds. Tenax adsorbent resin was used in the microtrap, and a porous layer, open tubular GC capillary column was used for separation. MS was operated in the full-scan mode, identification was based on the Automated Mass Spectral Deconvolution and Identification System, and quantification was based on extracted ions. The limits of quantification for EG, GA, and FA in blood were 10, 50, and 30 mg/L, respectively, and the expanded uncertainties of measurement were 20%, 16%, and 14%, respectively. The procedure allowed for the first time the inclusion of EG and GA as their methyl derivatives within a quantitative HS analysis. The ITEX method described here was more sensitive for analysis of volatile organic compounds than the corresponding static headspace analysis as demonstrated for 11 representative compounds. PMID:20406534

  13. Chiral nano-liquid chromatography-mass spectrometry applied to amino acids analysis for orange juice profiling.

    PubMed

    D'Orazio, Giovanni; Cifuentes, Alejandro; Fanali, Salvatore

    2008-06-01

    Determination of amino acid enantiomers is a very important topic in food analysis, since the presence of d-isomers may indicate, e.g., adulteration, microbiological contamination, uncontrolled fermentation processes, etc. In fact, the d- and l-enantiomers contents can be a useful marker for several elements such as quality control, contamination detection, processing monitoring, etc. Here we studied the potentiality of nano-liquid chromatography (nano-LC) coupled with mass spectrometry for the enantiomeric separation of several d- and l-amino acids that can be found in food products. Analytes were derivatized with fluorescein isothiocyanate (FITC). The mixture was injected and compounds focused on a C18 cartridge, then nano-LC analysis was carried out in a capillary column (75?m i.d.) packed with vancomycin-modified silica-diol particles. The effect of some experimental parameters, such as pH and buffer concentration on enantioresolution and retention factors, was studied for method optimization. The chromatographic separation system was coupled with an ion-trap mass spectrometer through a nano spray interface. It provided a final evaluation on analytes detected in all investigated samples with LOD values as low as 8ng/mL. That method was applied to the comparative analysis of two different orange juice samples (fresh natural vs. commercial one). Obtained profiles confirmed expected high quality standards. In fact, they mainly contained l-amino acids forms and not their antipodes. PMID:26065779

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

    SciTech Connect

    Esteban, N.V.; Yergey, A.L. (National Institute of Child Health and Human Development, Bethesda, MD (USA))

    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.

  15. Membrane assisted solvent extraction coupled to large volume injection-gas chromatography-mass spectrometry for trace analysis of synthetic musks in environmental water samples.

    PubMed

    Posada-Ureta, O; Olivares, M; Navarro, P; Vallejo, A; Zuloaga, O; Etxebarria, N

    2012-03-01

    This work describes the optimisation, validation and application of membrane assisted solvent extraction (MASE) together with a large volume injection (LVI) in a programmable temperature vaporisation (PTV) injector coupled to gas chromatography-mass spectrometry (GC-MS) for the quantification of ten synthetic musk fragrances (musks) in surface and wastewater samples. Regarding the MASE, musks were extracted from 150 mL of aqueous samples to 200 ?L of n-hexane hold in home-made low density polyethylene (LDPE) bags. The extraction took 240 min and the performance of the method made possible the direct analysis of the extracts by LVI-PTV-GC-MS without needing any further treatment and avoiding losses of analytes. During the optimisation of LVI-PTV set-up, the response surfaces of every analyte signal against the cryo-focussing temperature, injection speed and vent time were built. Finally, the figures of merit of the whole procedure allowed the analysis of most of the musks owing to the low method detection limits (between 4 and 25 ng L?¹) and good precisions (<20%). In fact, this method was successfully applied to the analysis of musks in surface and wastewater samples. Galaxolide and tonalide are the main two synthetic musks observed in most of the analysed environmental water samples. PMID:22265174

  16. Rapid method for the determination of 16 organochlorine pesticides in sesame seeds by microwave-assisted extraction and analysis of extracts by gas chromatography-mass spectrometry.

    PubMed

    Papadakis, Emmanouil N; Vryzas, Zisis; Papadopoulou-Mourkidou, Euphemia

    2006-09-15

    A method for the multiresidue analysis of 16 organochlorine insecticides in sesame seeds has been developed. The method is based on the microwave-assisted extraction (MAE) of the sesame seeds by the use of a water-acetonitrile mixture followed by Florisil clean-up of the extracts and subsequent analysis by gas chromatography-mass spectrometry (GC/MS) in the selected ion monitoring (SIM) mode. MAE operational parameters (extraction solvent, temperature and time, extractant volume) were optimized with respect to extraction efficiency of the target compounds from sesame seeds with 46% oil content. Recoveries >80% with relative standard deviations (RSD) <12% were obtained for all compounds under the selected parameters. The Florisil clean-up step proved sufficient for the removal of co-extracted substances so that no adverse effect on the chromatographic system was observed. Limit of quantification (LOQ) values were in the range of 5-10 microg/kg. The proposed method was applied in the analysis of sesame seed samples imported to Greece. PMID:16797565

  17. A NEW METHOD OF PEAK DETECTION FOR ANALYSIS OF COMPREHENSIVE TWO-DIMENSIONAL GAS CHROMATOGRAPHY MASS SPECTROMETRY DATA.

    PubMed

    Kim, Seongho; Ouyang, Ming; Jeong, Jaesik; Shen, Changyu; Zhang, Xiang

    2014-06-01

    We develop a novel peak detection algorithm for the analysis of comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOF MS) data using normal-exponential-Bernoulli (NEB) and mixture probability models. The algorithm first performs baseline correction and denoising simultaneously using the NEB model, which also defines peak regions. Peaks are then picked using a mixture of probability distribution to deal with the co-eluting peaks. Peak merging is further carried out based on the mass spectral similarities among the peaks within the same peak group. The algorithm is evaluated using experimental data to study the effect of different cut-offs of the conditional Bayes factors and the effect of different mixture models including Poisson, truncated Gaussian, Gaussian, Gamma, and exponentially modified Gaussian (EMG) distributions, and the optimal version is introduced using a trial-and-error approach. We then compare the new algorithm with two existing algorithms in terms of compound identification. Data analysis shows that the developed algorithm can detect the peaks with lower false discovery rates than the existing algorithms, and a less complicated peak picking model is a promising alternative to the more complicated and widely used EMG mixture models. PMID:25264474

  18. Analysis of novel hydroperoxides and other metabolites of oleic, linoleic, and linolenic acids by liquid chromatography-mass spectrometry with ion trap MSn.

    PubMed

    Oliw, E H; Su, C; Skogström, T; Benthin, G

    1998-09-01

    Linoleate is oxygenated by manganese-lipoxygenase (Mn-LO) to 11S-hydroperoxylinoleic acid and 13R-hydroperoxyoctadeca-9Z,11E-dienoic acid, whereas linoleate diol synthase (LDS) converts linoleate sequentially to 8R-hydroperoxylinoleate, through an 8-dioxygenase by insertion of molecular oxygen, and to 7S,8S-dihydroxylinoleate, through a hydroperoxide isomerase by intramolecular oxygen transfer. We have used liquid chromatography-mass spectrometry (LC-MS) with an ion trap mass spectrometer to study the MSn mass spectra of the main metabolites of oleic, linoleic, alpha-linolenic and gamma-linolenic acids, which are formed by Mn-LO and by LDS. The enzymes were purified from the culture broth (Mn-LO) and mycelium (LDS) of the fungus Gaeumannomyces graminis. MS3 analysis of hydroperoxides and MS2 analysis of dihydroxy- and monohydroxy metabolites yielded many fragments with information on the position of oxygenated carbons. Mn-LO oxygenated C-11 and C-13 of 18:2n-6, 18:3n-3, and 18:3n-6 in a ratio of approximately 1:1-3 at high substrate concentrations. 8-Hydroxy-9(10)epoxystearate was identified as a novel metabolite of LDS and oleic acid by LC-MS and by gas chromatography-MS. We conclude that LC-MS with MSn is a convenient tool for detection and identification of hydroperoxy fatty acids and other metabolites of these enzymes. PMID:9778131

  19. Development of a fast extraction method and optimization of liquid chromatography-mass spectrometry for the analysis of phenolic compounds in lentil seed coats.

    PubMed

    Mirali, Mahla; Ambrose, Stephen J; Wood, Stephen A; Vandenberg, Albert; Purves, Randy W

    2014-10-15

    A systematic set of optimization experiments was conducted to design an efficient extraction and analysis protocol for screening six different sub-classes of phenolic compounds in the seed coat of various lentil (Lens culinaris Medik.) genotypes. Different compounds from anthocyanidins, flavan-3-ols, proanthocyanidins, flavanones, flavones, and flavonols sub-classes were first optimized for use as standards for liquid chromatography mass spectrometry (LC-MS) with UV detection. The effect of maceration duration, reconstitution solvent, and extraction solvent were investigated using lentil genotype CDC Maxim. Chromatographic conditions were optimized by examining column separation efficiencies, organic composition, and solvent gradient. The results showed that a 1h maceration step was sufficient and that non-acidified solvents were more appropriate; a 70:30 acetone: water (v/v) solvent was ultimately selected. Using a Kinetex PFP column, the organic concentration, gradient, and flow rate were optimized to maximize the resolution of phenolic compounds in a short 30-min analysis time. The optimized method was applied to three lentil genotypes with different phenolic compound profiles to provide information of value to breeding programs. PMID:25173496

  20. Study of solvent sublation for concentration of trace phthalate esters in plastic beverage packaging and analysis by gas chromatography-mass spectrometry.

    PubMed

    Chang, Lin; Bi, Pengyu; Li, Xiaochen; Wei, Yun

    2015-06-15

    A novel trace analytical method based on solvent sublation (SS) and gas chromatography-mass spectrometry (GC-MS) was developed for the trace determination of twenty-two phthalate esters (PAEs) from plastic beverage packaging. In the solvent sublation section, the effects of solution pH, NaCl concentration, nitrogen flow rate, and sublation time on the sublation efficiency were investigated in detail, and the optimal conditions were obtained. The trace PAEs migrated from plastic beverage packaging to food simulants were separated and concentrated by solvent sublation, and then the trace target compounds in the concentrated solution were analyzed by GC-MS. According to the European Union Regulation, the food simulants including distilled water for the normal beverages and acetic acid solution (3%) for the acetic beverage of yogurt were prepared for migration tests. The trace analysis method showed good linearity, low limits of detection (LODs) of 1.6-183.5 ng/L, and satisfied recoveries (67.3-113.7%). PMID:25660867

  1. A peaklet-based generic strategy for the untargeted analysis of comprehensive two-dimensional gas chromatography mass spectrometry data sets.

    PubMed

    Egert, Björn; Weinert, Christoph H; Kulling, Sabine E

    2015-07-31

    Comprehensive two-dimensional gas chromatography mass spectrometry (GC×GC-MS) is a well-established key technology in analytical chemistry and increasingly used in the field of untargeted metabolomics. However, automated processing of large GC×GC-MS data sets is still a major bottleneck in untargeted, large-scale metabolomics. For this reason we introduce a novel peaklet-based alignment strategy. The algorithm is capable of an untargeted deterministic alignment exploiting a density based clustering procedure within a time constrained similarity matrix. Exploiting minimal (1)D and (2)D retention time shifts between peak modulations, the alignment is done without the need for peak merging which also eliminates the need for linear or nonlinear retention time correction procedures. The approach is validated in detail using data of urine samples from a large human metabolomics study. The data was acquired by a Shimadzu GCMS-QP2010 Ultra GC×GC-qMS system and consists of 512 runs, including 312 study samples and 178 quality control sample injections, measured within a time period of 22 days. The final result table consisted of 313 analytes, each of these being detectable in at least 75% of the study samples. In summary, we present an automated, reliable and fully transparent workflow for the analysis of large GC×GC-qMS metabolomics data sets. PMID:26074098

  2. Analysis of 35 priority semivolatile compounds in water by stir bar sorptive extraction-thermal desorption-gas chromatography-mass spectrometry. I. Method optimisation.

    PubMed

    León, V M; Alvarez, B; Cobollo, M A; Muñoz, S; Valor, I

    2003-05-30

    A multiresidue method for the determination of 35 organic micropollutants (pesticides and polycyclic aromatic hydrocarbons) in water has been optimised using stir bar sorptive extraction (SBSE) and thermal desorption coupled to capillary gas chromatography-mass spectrometry (GC-MS). In the present work, the different parameters affecting the extraction of the analytes from the water samples to the PDMS-coated stir bars and optimisation of conditions affecting thermal desorption are investigated. The optimised conditions consist of a 100-ml water sample with 20% NaCl addition extracted with 20 mm length x 0.5 mm film thickness stir bars at 900 rpm during 14 h at ambient temperature. Desorption is carried out at 280 degrees C during 6 min under a helium flow of 75 ml/min in the splitless mode while maintaining a cryofocusing temperature of 20 degrees C in the programmed-temperature vaporisation (PTV) injector of the GC-MS system. Finally, the PTV injector is ramped to a temperature of 280 degrees C and the analytes are separated in the GC and detected by MS using full scan mode (m/z 60-400). Under the described conditions, the good repeatability, high analyte recoveries and robustness, make SBSE a powerful tool for routine quality control analysis of the selected semivolatile compounds in water samples. PMID:12885055

  3. Compensation for matrix effects in the gas chromatography-mass spectrometry analysis of 186 pesticides in tea matrices using analyte protectants.

    PubMed

    Li, Yan; Chen, Xi; Fan, Chunlin; Pang, Guofang

    2012-11-30

    A gas chromatography-mass spectrometry (GC-MS) analytical method was developed for simultaneously determining 186 pesticides in tea matrices using analyte protectants to counteract the matrix-induced effect. The matrix effects were evaluated for green, oolong and black tea, representing unfermented, partially fermented and completely fermented teas respectively and depending on the type of tea, 72%, 94% and 94% of the pesticides presented strong response enhancement effect. Several analyte protectants as well as certain combinations of these protectants were evaluated to check their compensation effects. A mixture of triglycerol and d-ribonic acid-?-lactone (both at 2mg/mL in the injected samples) was found to be the most effective in improving the chromatographic behavior of the 186 pesticides. More than 96% of the 186 pesticides achieved recoveries within the range of 70-120% when using the selected mixture of analyte protectants. The simple addition of analyte protectants offers a more convenient solution to overcome matrix effects, results in less active sites compared to matrix-matched standardization and can be an effective approach to compensate for matrix effects in the GC-MS analysis of pesticide residues. PMID:23102633

  4. Identification of odorants in frankincense (Boswellia sacra Flueck.) by aroma extract dilution analysis and two-dimensional gas chromatography-mass spectrometry/olfactometry.

    PubMed

    Niebler, Johannes; Buettner, Andrea

    2015-01-01

    Frankincense has been known, traded and used throughout the ages for its exceptional aroma properties, and is still commonly used in both secular and religious settings to convey a pleasant odor. Surprisingly, the odoriferous principle(s) underlying its unique odor profile have never been published. In this study, resin samples of Boswellia sacra Flueck. from both Somalia and Oman were investigated by aroma extract dilution analysis. In a comprehensive, odor-activity guided approach both chemo-analytical and human-sensory parameters were used to identify odor active constituents of the volatile fraction of B. sacra. Among the key odorants found were ?-pinene, ?-myrcene, linalool, p-cresol and two unidentified sesquiterpenoids. Overall, a total of 23 odorants were detected and analyzed by gas chromatography-olfactometry and heart-cut two-dimensional gas chromatography-mass spectrometry/olfactometry. The majority of the identified odorant compounds were oxygenated monoterpenes, along with some relevant mono- and sesquiterpenes and only one diterpenoid substance. Several of these compounds were reported here for the first time as odorous constituents in B. sacra. Identifying bioactive compounds might support a better understanding with regard to the potential benefits of frankincense, for example in aromatherapy or ecclesial settings. PMID:25468535

  5. Pyrolysis kinetic and product analysis of different microalgal biomass by distributed activation energy model and pyrolysis-gas chromatography-mass spectrometry.

    PubMed

    Yang, Xuewei; Zhang, Rui; Fu, Juan; Geng, Shu; Cheng, Jay Jiayang; Sun, Yuan

    2014-07-01

    To assess the energy potential of different microalgae, Chlorella sorokiniana and Monoraphidium were selected for studying the pyrolytic behavior at different heating rates with the analytical method of thermogravimetric analysis (TG), distributed activation energy model (DAEM) and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). Results presented that Monoraphidium 3s35 showed superiority for pyrolysis at low heating rate. Calculated by DAEM, during the conversion rate range from 0.1 to 0.7, the activation energies of C. sorokiniana 21 were much lower than that of Monoraphidium 3s35. Both C. sorokiniana 21 and Monoraphidium 3s35 can produce certain amount (up to 20.50%) of alkane compounds, with 9-Octadecyne (C18H34) as the primary compound. Short-chain alkanes (C7-C13) with unsaturated carbon can be released in the pyrolysis at 500°C for both microalgal biomass. It was also observed that the pyrolysis of C. sorokiniana 21 released more alcohol compounds, while Monoraphidium 3s35 produced more saccharides. PMID:24835746

  6. High-resolution gas chromatography/mass spectrometry method for characterization and quantitative analysis of ginkgolic acids in Ginkgo biloba plants, extracts, and dietary supplements.

    PubMed

    Wang, Mei; Zhao, Jianping; Avula, Bharathi; Wang, Yan-Hong; Avonto, Cristina; Chittiboyina, Amar G; Wylie, Philip L; Parcher, Jon F; Khan, Ikhlas A

    2014-12-17

    A high-resolution gas chromatography/mass spectrometry (GC/MS) with selected ion monitor method focusing on the characterization and quantitative analysis of ginkgolic acids (GAs) in Ginkgo biloba L. plant materials, extracts, and commercial products was developed and validated. The method involved sample extraction with (1:1) methanol and 10% formic acid, liquid-liquid extraction with n-hexane, and derivatization with trimethylsulfonium hydroxide (TMSH). Separation of two saturated (C13:0 and C15:0) and six unsaturated ginkgolic acid methyl esters with different positional double bonds (C15:1 ?8 and ?10, C17:1 ?8, ?10, and ?12, and C17:2) was achieved on a very polar (88% cyanopropyl) aryl-polysiloxane HP-88 capillary GC column. The double bond positions in the GAs were determined by ozonolysis. The developed GC/MS method was validated according to ICH guidelines, and the quantitation results were verified by comparison with a standard high-performance liquid chromatography method. Nineteen G. biloba authenticated and commercial plant samples and 21 dietary supplements purported to contain G. biloba leaf extracts were analyzed. Finally, the presence of the marker compounds, terpene trilactones and flavonol glycosides for Ginkgo biloba in the dietary supplements was determined by UHPLC/MS and used to confirm the presence of G. biloba leaf extracts in all of the botanical dietary supplements. PMID:25383633

  7. Development of sample clean up methods for the analysis of Mycobacterium tuberculosis methyl mycocerosate biomarkers in sputum extracts by gas chromatography–mass spectrometry

    PubMed Central

    Nicoara, Simona C.; Turner, Nicholas W.; Minnikin, David E.; Lee, Oona Y.-C.; O'Sullivan, Denise M.; McNerney, Ruth; Mutetwa, Reggie; Corbett, Liz E.; Morgan, Geraint H.

    2015-01-01

    A proof of principle gas chromatography–mass spectrometry method is presented, in combination with clean up assays, aiming to improve the analysis of methyl mycocerosate tuberculosis biomarkers from sputum. Methyl mycocerosates are generated from the transesterification of phthiocerol dimycocerosates (PDIMs), extracted in petroleum ether from sputum of tuberculosis suspect patients. When a high matrix background is present in the sputum extracts, the identification of the chromatographic peaks corresponding to the methyl derivatives of PDIMs analytes may be hindered by the closely eluting methyl ether of cholesterol, usually an abundant matrix constituent frequently present in sputum samples. The purification procedures involving solid phase extraction (SPE) based methods with both commercial Isolute-Florisil cartridges, and purpose designed molecularly imprinted polymeric materials (MIPs), resulted in cleaner chromatograms, while the mycocerosates are still present. The clean-up performed on solutions of PDIMs and cholesterol standards in petroleum ether show that, depending on the solvent mix and on the type of SPE used, the recovery of PDIMs is between 64 and 70%, whilst most of the cholesterol is removed from the system. When applied to petroleum ether extracts from representative sputum samples, the clean-up procedures resulted in recoveries of 36–68% for PDIMs, allowing some superior detection of the target analytes. PMID:25728371

  8. Development and optimization of a gas chromatography/mass spectrometry method for the analysis of thermochemolytic degradation products of phthiocerol dimycocerosate waxes found in Mycobacterium tuberculosis

    PubMed Central

    Nicoara, Simona C; Minnikin, David E; Lee, Oona C Y; O'Sullivan, Denise M; McNerney, Ruth; Pillinger, Collin T; Wright, Ian P; Morgan, Geraint H

    2013-01-01

    RATIONALE:?The phthiocerol dimycocerosates (PDIMs) are certain stable and hydrophobic waxes found in the cell membrane of Mycobacterium tuberculosis, bacteria that cause an infectious disease of growing concern worldwide. Previous studies report the analysis of derivatives of the hydrolysed PDIMs from biological samples, following complex extraction and offline derivatization of PDIMs biomarkers, prior to their analysis by gas chromatography/mass spectrometry (GC/MS). METHODS:?We developed and optimized a GC/MS method based on selected ion monitoring (SIM) to detect the derivatives produced via the thermally assisted hydrolysis and methylation (THM) of the PDIMs from the cell membrane of M. tuberculosis. The extraction of PDIMs from culture is simple, and their thermochemolysis is carried out automatically online, thus avoiding the time-consuming derivatization steps of hydrolysis and esterification, usually performed offline. RESULTS:?For standard PDIMs in petroleum ether, our optimized method gave an excellent linearity (R2?=?0.99) at concentrations between 0.172 and 27.5?ng/mL, a good precision (RSD?=?11.42 %), and a limit of detection (LOD) of 100?pg/mL. For the PDIMs extracted from dilutions of M. tuberculosis culture, the method gave good linearity (R2?=?0.9685) and an estimated LOD of 400?CFU/mL (CFU?=?colony forming units) in sterile distilled water. CONCLUSIONS:?A GC/MS(SIM) method is presented for the rapid and quantitative detection of M. tuberculosis, based on the online thermochemolysis of lipidic biomarkers extracted from the bacterial culture. The method has the potential to be applied in human and veterinary clinical laboratories for the rapid diagnosis of tuberculosis in infected biological samples. © 2013 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley & Sons, Ltd. PMID:24097393

  9. Supported liquid membrane-liquid chromatography-mass spectrometry analysis of cyanobacterial toxins in fresh water systems

    NASA Astrophysics Data System (ADS)

    Mbukwa, Elbert A.; Msagati, Titus A. M.; Mamba, Bhekie B.

    Harmful algal blooms (HABs) are increasingly becoming of great concern to water resources worldwide due to indiscriminate waste disposal habits resulting in water pollution and eutrophication. When cyanobacterial cells lyse (burst) they release toxins called microcystins (MCs) that are well known for their hepatotoxicity (causing liver damage) and have been found in eutrophic lakes, rivers, wastewater ponds and other water reservoirs. Prolonged exposure to low concentrated MCs are equally of health importance as they are known to be bioaccumulative and even at such low concentration do exhibit toxic effects to aquatic animals, wildlife and human liver cells. The application of common treatment processes for drinking water sourced from HABs infested reservoirs have the potential to cause algal cell lyses releasing low to higher amounts of MCs in finished water. Trace microcystins in water/tissue can be analyzed and quantified using Liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) following solid-phase extraction (SPE) sample clean-up procedures. However, extracting MCs from algal samples which are rich in chlorophyll pigments and other organic matrices the SPE method suffers a number of drawbacks, including cartridge clogging, long procedural steps and use of larger volumes of extraction solvents. We applied a supported liquid membrane (SLM) based technique as an alternative sample clean-up method for LC-ESI-MS analysis of MCs from both water and algal cells. Four (4) MC variants (MC-RR, -YR, -LR and -WR) from lyophilized cells of Microcystis aeruginosa and water collected from a wastewater pond were identified) and quantified using LC-ESI-MS following a SLM extraction and liquid partitioning step, however, MC-WR was not detected from water extracts. Within 45 min of SLM extraction all studied MCs were extracted and pre-concentrated in approximately 15 ?L of an acceptor phase at an optimal pH 2.02 of the donor phase (sample). The highest total quantifiable intracellular and extracellular MCs were 37.039 ± 0.087 ?g/g DW and 5.123 ± 0.018 ?g/L, respectively. The concentrations of MC-RR were the highest from all samples studied recording maximum values of 21.579 ± 0.066 ?g/g DW and 3.199 ± 0.012 ?g/L for intracellular and extracellular quantities, respectively.

  10. Ion chromatography-mass spectrometry: a review of recent technologies and applications in forensic and environmental explosives analysis.

    PubMed

    Barron, Leon; Gilchrist, Elizabeth

    2014-01-01

    The development and application of ion chromatography (IC) coupled to mass spectrometry (MS) is discussed herein for the quantitative determination of low-order explosives-related ionic species in environmental and forensic sample types. Issues relating to environmental explosives contamination and the need for more confirmatory IC-MS based applications in forensic science are examined. In particular, the compatibility of a range of IC separation modes with MS detection is summarised along with the analytical challenges that have been overcome to facilitate determinations at the ng-?g L(-1) level. Observed trends in coupling IC to inductively coupled plasma and electrospray ionisation mass spectrometry form a particular focus. This review also includes a discussion of the relative performance of reported IC-MS methods in comparison to orthogonal ion separation-based, spectrometric and spectroscopic approaches to confirmatory detection of low-order explosives. Finally, some promising areas for future research are highlighted and discussed with respect to potential IC-MS applications. PMID:24331039

  11. Rapid diagnosis of phenylketonuria and other aminoacidemias by quantitative analysis of amino acids in neonatal blood spots by gas chromatography-mass spectrometry.

    PubMed

    Deng, Chunhui; Shang, Chunqing; Hu, Yaoming; Zhang, Xiangmin

    2002-07-25

    A new method for quantifying specific amino acids in small volumes of plasma and whole blood has been developed. Volatile derivatives of amino acids are analyzed by gas chromatography-mass spectrometry. The method only takes a few minutes to perform and requires minimal sample preparation. The accurate assay of phenylalanine, tyrosine and other amino acids in dried blood spots could be used for neonatal screening for phenylketonuria and other aminoacidemias. Because of the low cost, this neonatal screening method is suited to application in developing countries such as China. PMID:12101068

  12. Evaluation of the QuEChERS Method and Gas Chromatography–Mass Spectrometry for the Analysis Pesticide Residues in Water and Sediment

    PubMed Central

    de Macedo, A. N.; Vicente, G. H. L.; Nogueira, A. R. A.

    2010-01-01

    A method for the determination of pesticide residues in water and sediment was developed using the QuEChERS method followed by gas chromatographymass spectrometry. The method was validated in terms of accuracy, specificity, linearity, detection and quantification limits. The recovery percentages obtained for the pesticides in water at different concentrations ranged from 63 to 116%, with relative standard deviations below 12%. The corresponding results from the sediment ranged from 48 to 115% with relative standard deviations below 16%. The limits of detection for the pesticides in water and sediment were below 0.003 mg L?1 and 0.02 mg kg?1, respectively. PMID:21165598

  13. Optimization of large volume injection-programmable temperature vaporization-gas chromatography–mass spectrometry analysis for the determination of estrogenic compounds in environmental samples

    Microsoft Academic Search

    A. Vallejo; L. A. Fernández; M. Olivares; A. Prieto; N. Etxebarria; A. Usobiaga; O. Zuloaga

    2010-01-01

    Large volume injection-programmable temperature vaporization-gas chromatography–mass spectrometry (LVI-PTV-GC–MS) was optimized for the determination of estrone (E1), 17?-estradiol (E2), 17?-ethynyl estradiol (EE2), mestranol (MeEE2) and estriol (E3) for their determination in environmental samples (estuarine water, wastewater, fish bile and fish homogenate) after derivatization with 25?L (BSTFA+1% TMCS) and 125?L of pyridine. Experimental designs such as Plackett–Burman (PBD) and central composite designs

  14. Derivatization and fragmentation pattern analysis of natural and synthetic steroids, as their trimethylsilyl (oxime) ether derivatives by gas chromatography mass spectrometry: analysis of dissolved steroids in wastewater samples.

    PubMed

    Andrási, N; Helenkár, A; Záray, Gy; Vasanits, A; Molnár-Perl, I

    2011-04-01

    This paper reports the extension of our multiresidue analysis (MA) procedure with 18 natural and synthetic steroids; permitting the identification and quantification, in total of 81 pollutants from one solution, by a single injection, as their trimethylsilyl (TMS)-oxime ether/ester derivatives, by gas chromatography-mass spectrometry (GC-MS), within 31 min. As a novelty to the field, basic researches, such as fragmentation pattern analysis and derivatization optimization studies were performed for androsterone, transdehydroandrosterone, transandrosterone, mestranol, dihydrotestosterone, ethinylestradiol, testosterone, norethisterone, estriol, 4-androstene-3,17-dione, gestodene, levonorgestrel, etonogestrel, coprostanol, progesterone, cholesterol, medroxy-progesterone-acetate, stigmasterol and ?-sitosterol. Results confirmed that (i) the TMS oxime-ether derivatives of the keto steroids provide from 1.40 times (gestodene) up to 4.25 times (norethisterone) higher responses compared to their TMS-ether ones, and (ii) the distribution of syn/anti oximes is characteristic to the ketosteroid species examined. Based on our optimized mass fragmentation, solid phase extraction (SPE) and derivatization studies separations have been performed in the total ion current (TIC) mode, identification and quantification of compounds have been carried out on the basis of their selective fragment ions. Responses, obtained with derivatized standards proved to be linear (hydroxysteroids), or have been calculated from calibration curves (ketosteroids) in the range of 1.88-750ng/L levels. Limit of quantitation (LOQ) values varied between 1.88ng/L and 37.5ng/L concentrations. The most important practical messages of this work are the high androsterone (0.744-4.28?g/L), transandrosterone (0.138-4.00?g/L), coprostanol (2.11-302?g/L), cholesterol (0.308-41?g/L), stigmasterol (1.21-8.40?g/L) and ?-sitosterol (1.12-11.0?g/L) contents of influent wastewaters. ?-Estradiol (100ng/L) and estriol (54ng/L) were found in one influent sample, only. Reproducibilities, characterized with the relative standard deviation percentages (RSD%) of measurements, varied between 1.73 RSD% (?-estradiol) and 5.4 RSD% (stigmasterol), with an average of 4.82 RSD%. PMID:21367426

  15. Dispersive micro solid-phase extraction for the rapid analysis of synthetic polycyclic musks using thermal desorption gas chromatography-mass spectrometry.

    PubMed

    Chung, Wu-Hsun; Tzing, Shin-Hwa; Ding, Wang-Hsien

    2013-09-13

    A simple and solvent-free method for the rapid analysis of five synthetic polycyclic musks in water samples is described. The method involves the use of dispersive micro solid-phase extraction (D-?-SPE) coupled with direct thermal desorption (TD) gas chromatography-mass spectrometry (GC-MS) operating in the selected-ion-storage (SIS) mode. The parameters affecting the extraction efficiency of the target analytes from water sample and the thermal desorption conditions in the GC injection-port were optimized using a central composite design method. The optimal extraction conditions involved immersing 3.2mg of a typical octadecyl (C18) bonded silica adsorbent (i.e., ENVI-18) in a 10mL water sample. After extraction by vigorously shaking for 1.0min, the adsorbents were collected and dried on a filter. The adsorbents were transferred to a micro-vial, which was directly inserted into GC temperature-programmed injector, and the extracted target analytes were then thermally desorbed in the GC injection-port at 337°C for 3.8min. The limits of quantitation (LOQs) were determined to be 1.2-3.0ng/L. Precision, as indicated by relative standard deviations (RSDs), was less than 9% for both intra- and inter-day analysis. Accuracy, expressed as the mean extraction recovery, was between 74 and 90%. A preliminary analysis of the river water samples revealed that galaxolide (HHCB) and tonalide (AHTN) were the two most common synthetic polycyclic musks present. Using a standard addition method, their concentrations were determined to in the range from 11 to 140ng/L. PMID:23932027

  16. High temperature-ultra performance liquid chromatography-mass spectrometry for the metabonomic analysis of Zucker rat urine.

    PubMed

    Gika, Helen G; Theodoridis, Georgios; Extance, Jon; Edge, Anthony M; Wilson, Ian D

    2008-08-15

    The applicability and potential of using elevated temperatures and sub 2-microm porous particles in chromatography for metabonomics/metabolomics was investigated using, for the first time, solvent temperatures higher than the boiling point of water (up to 180 degrees C) and thermal gradients to reduce the use of organic solvents. Ultra performance liquid chromatography, combined with mass spectrometry, was investigated for the global metabolite profiling of the plasma and urine of normal and Zucker (fa/fa) obese rats (a well established disease animal model). "Isobaric" high temperature chromatography, where the temperature and flow rate follow a gradient program, was developed and evaluated against a conventional organic solvent gradient. LC-MS data were first examined by established chromatographic criteria in order to evaluate the chromatographic performance and next were treated by special peak picking algorithms to allow the application of multivariate statistics. These studies showed that, for urine (but not plasma), chromatography at elevated temperatures provided better results than conventional reversed-phase LC with higher peak capacity and better peak asymmetry. From a systems biology point of view, better group clustering and separation was obtained with a larger number of variables of high importance when using high temperature-ultra performance liquid chromatography (HT-UPLC) compared to conventional solvent gradients. PMID:18485837

  17. Estimation of brassylic acid by gas chromatography-mass spectrometry

    SciTech Connect

    Mohammed J. Nasrullah, Erica N. Pfarr, Pooja Thapliyal, Nicholas S. Dusek, Kristofer L. Schiele, Christy Gallagher-Lein, and James A. Bahr

    2010-10-29

    The main focus of this work is to estimate Brassylic Acid (BA) using gas chromatography-mass spectrometry (GC-MS). BA is a product obtained from the oxidative cleavage of Erucic Acid (EA). BA has various applications for making nylons and high performance polymers. BA is a 13 carbon compound with two carboxylic acid functional groups at the terminal end. BA has a long hydrocarbon chain that makes the molecule less sensitive to some of the characterization techniques. Although BA can be characterized by NMR, both the starting material (EA) and products BA and nonanoic acid (NA) have peaks at similar {delta}, ppm values. Hence it becomes difficult for the quick estimation of BA during its synthesis.

  18. The toxicity of 3-chloropropane-1,2-dipalmitate in Wistar rats and a metabonomics analysis of rat urine by ultra-performance liquid chromatography-mass spectrometry.

    PubMed

    Li, Jianshuang; Wang, Sen; Wang, Maoqing; Shi, Wenxiu; Du, Xiaoyan; Sun, Changhao

    2013-11-25

    3-Monochloropropane-1,2-diol(3-MCPD) fatty acid esters can release free 3-MCPD in a certain condition. Free 3-MCPD is a well-known food contaminant and is toxicological well characterized, however, in contrast to free 3-MCPD, the toxicological characterization of 3-MCPD fatty acid esters is puzzling. In this study, toxicological and metabonomics studies of 3-chloropropane-1,2-dipalmitate(3-MCPD dipalmitate) were carried out based on an acute oral toxicity test, a 90-day feeding test and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) analysis. The LD50 value of 3-MCPD dipalmitate was determined to be 1780 mg/kg body weight (bw) for Wistar rats. The results of the 90-day feeding test in male Wistar rats showed that 3-MCPD dipalmitate caused a significant increase in blood urea nitrogen and creatinine in the high-dose group (267 mg/kg bw/day) compared to control rats. Renal tubular epithelium cell degeneration and renal tubular hyaline cast accumulation were the major histopathological changes in rats administered 3-MCPD dipalmitate. Urine samples obtained after the 90-day feeding test and analyzed by UPLC-MS showed that the differences in metabolic profiles between control and treated rats were clearly distinguished by partial least squares-discriminant analysis (PLS-DA) of the chromatographic data. Five metabolite biomarkers which had earlier and significant variations had been identified, they were first considered to be the early, sensitive biomarkers in evaluating the effect of 3-MCPD dipalmitate exposure, and the possible mechanism of these biomarkers variation was elucidated. The combination of histopathological examination, clinical chemistry and metabolomics analyses in rats resulted in a systematic and comprehensive assessment of the long-term toxicity of 3-MCPD dipalmitate. PMID:24140137

  19. Automated and sensitive analysis of 28-epihomobrassinolide in Arabidopsis thaliana by on-line polymer monolith microextraction coupled to liquid chromatography-mass spectrometry.

    PubMed

    Wang, Xin; Ma, Qiao; Li, Min; Chang, Cuilan; Bai, Yu; Feng, Yuqi; Liu, Huwei

    2013-11-22

    By on-line solid phase microextraction with polymer monolith coupled to liquid chromatography-mass spectrometry (SPME-LC-MS), an automated and sensitive method for analysis of the endogenous 28-epihomobrassinolide (28-epihomoBR) in Arabidopsis thaliana was developed in this work. Firstly, a poly(methacrylic acid-co-ethylene dimethacrylate) (poly(MAA-co-EDMA)) monolith was prepared in the capillary and applied in in-tube SPME. Polyethylene glycol (PEG) was used as porogen to adjust the specific surface area and hydrophobicity of the target monolith to get satisfactory permeability, high mechanical strength and good stability. The optimized monolith was then served as extraction medium for analysis of the derivatized 28-epihomoBR in plant samples with the cleanup of matrix and enrichment of desired analyte at the same time. Good linearity was obtained in the linear range of 5-500 ng/L with the coefficient of determination (R(2)) of 0.9996. The limit of detection (S/N=3) of 28-epihomoBR was found to be 2.0 ng/L and the limit of quantification (S/N=10) was 5.0 ng/L. Using this method, the endogenous 0.101 ng/g (FW) 28-epihomoBR was successfully detected from only 400mg A. thaliana samples with satisfactory recovery (80.3-92.1%) and reproducibility (RSD 6.8-9.6%). Comparing with other sample pretreatment methods, this automated on-line SPME-LC-MS method is rapid, sensitive, reproducible and laborsaving. PMID:23915641

  20. Separation of Caffeine from Beverages and Analysis Using Thin-Layer Chromatography and Gas Chromatography-Mass Spectrometry

    ERIC Educational Resources Information Center

    Torres y Torres, Janelle L.; Hiley, Shauna L.; Lorimor, Steven P.; Rhoad, Jonathan S.; Caldwell, Benjamin D.; Zweerink, Gerald L.; Ducey, Michael

    2015-01-01

    The Characterization and Analysis of a Product (CAP) project is used to introduce first-semester general chemistry students to chemical instrumentation through the analysis of caffeine-containing beverage products. Some examples of these products have included coffee, tea, and energy drinks. Students perform at least three instrumental experiments…

  1. Sample collection and preparation of biofluids and extracts for gas chromatography-mass spectrometry.

    PubMed

    Emwas, Abdul-Hamid M; Al-Talla, Zeyad A; Kharbatia, Najeh M

    2015-01-01

    To maximize the utility of gas chromatography-mass spectrometry (GC-MS) in metabonomics research, all stages of the experimental design should be standardized, including sample collection, storage, preparation, and sample separation. Moreover, the prerequisite for any GC-MS analysis is that a compound must be volatile and thermally stable if it is to be analyzed using this technique. Since many metabolites are nonvolatile and polar in nature, they are not readily amenable to analysis by GC-MS and require initial chemical derivatization of the polar functional groups in order to reduce the polarity and to increase the thermal stability and volatility of the analytes. In this chapter, an overview is presented of the optimum approach to sample collection, storage, and preparation for gas chromatography-mass spectrometry-based metabonomics with particular focus on urine samples as example of biofluids. PMID:25677148

  2. EVALUATION OF PARTICLE BEAM LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY FOR THE ANALYSIS OF POLAR SEMIVOLATILE ORGANIC COMPOUNDS IN AIR SAMPLES

    EPA Science Inventory

    This report describes the initial evaluation of a particle beam liquid chromatograph/mass spectrometer for the analysis of polar semivolatile organic compounds in air samples. This study was concentrated on examining and optimizing instrumental operating parameters, evaluating th...

  3. Validation of an isotope dilution gas chromatography-mass spectrometry method for combined analysis of oxysterols and oxyphytosterols in serum samples.

    PubMed

    Schött, Hans-Frieder; Lütjohann, Dieter

    2015-07-01

    We describe the validation of a method for the analysis of oxysterols, i.e. oxycholesterols and oxyphytosterols, in human serum using gas chromatography-mass spectrometry selected ion monitoring (GC-MS-SIM). Concentrations of 7?- and 7?-hydroxy-, and 7oxo-cholesterol, -campesterol, and -sitosterol as well as 4?-hydroxycholesterol and side-chain oxygenated 24S-, 25-, and 27-hydroxycholesterol were determined by isotope dilution methodology. After saponification at room temperature the oxysterols were extracted, separated from their substrates, cholesterol, campesterol, and sitosterol, by solid phase extraction, and subsequently derivatised to their corresponding trimethylsilyl-ethers prior to GC-MS-SIM. In order to prevent artificial autoxidation butylated hydroxytoluene and ethylenediaminetetraacetic acid were added. The validation of the method was performed according to the International Conference on Harmonisation guidance, including limits of detection and quantification, ranges, recovery and precision. Due to improved instrumental settings and work-up procedure, limits of detection and quantification ranged between 8.0-202.0pg/mL and 28.0-674pg/mL, respectively. Recovery data in five calibration points varied between 91.9% and 116.8% and in serum samples between 93.1% and 118.1%. The mean coefficient of variation (CV) for the recovery of all compounds was <10%. Well satisfying CVs for within-day precision (2.1-10.8%) and for between-day precision (2.3-12.1%) were obtained. More than 20 samples could be processed in a single routine day and test series of about 300 samples can be realised without impairment of the validation parameters during a sequence. Comparison of oxysterol and oxyphytosterol content in serum and plasma revealed no difference. A fully validated isotope dilution methodology for the quantification of oxycholesterols and oxyphytosterols from human serum or plasma is presented. PMID:25701095

  4. Interfacing low-energy SAW nebulization with Liquid Chromatography-Mass Spectrometry for the analysis of biological samples

    PubMed Central

    Tveen-Jensen, Karina; Gesellchen, Frank; Wilson, Rab; Spickett, Corinne M.; Cooper, Jonathan M.; Pitt, Andrew R.

    2015-01-01

    Soft ionization methods for the introduction of labile biomolecules into a mass spectrometer are of fundamental importance to biomolecular analysis. Previously, electrospray ionization (ESI) and matrix assisted laser desorption-ionization (MALDI) have been the main ionization methods used. Surface acoustic wave nebulization (SAWN) is a new technique that has been demonstrated to deposit less energy into ions upon ion formation and transfer for detection than other methods for sample introduction into a mass spectrometer (MS). Here we report the optimization and use of SAWN as a nebulization technique for the introduction of samples from a low flow of liquid, and the interfacing of SAWN with liquid chromatographic separation (LC) for the analysis of a protein digest. This demonstrates that SAWN can be a viable, low-energy alternative to ESI for the LC-MS analysis of proteomic samples. PMID:25978651

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

    Microsoft Academic Search

    Renáta Myjavcová; Petr Marhol; Vladimír K?en; Vilím Šimánek; Jitka Ulrichová; Irena Palíková; Barbora Papoušková; Karel Lemr; Petr Bedná?

    2010-01-01

    Anthocyanins from the fruit Lonicera caerulea L. var. kamtschatica (blueberry honeysuckle, Caprifoliaceae) were studied via (semi)preparative chromatographic fractionation followed by MS and ?LC\\/MS analysis. The extraction procedure was optimized with respect to analytical purposes as well as its potential use for the preparation of nutraceuticals. The highest yield of anthocyanins was obtained using acidified methanol as the extraction medium. A

  6. Characterization of sterols by gas chromatography-mass spectrometry of the trimethylsilyl ethers

    Microsoft Academic Search

    C. J. W. Brooks; E. C. Horning; J. S. Young

    1968-01-01

    The utility of combined gas chromatography-mass spectrometry in the analysis and characterization of sterols has been explored.\\u000a Methylene unit (MU) values and principal mass spectrometric data are presented for trimethylsilyl ethers of 28 sterols, including\\u000a the major natural sterols. The diagnostic value of the fragmentation of trimethylsilyl ethers of ?5-3 ?-hydroxysteroids has been confirmed. Characteristic fragmentations of ?4-3 ?-trimethylsilyloxysteroids, and

  7. Determination of volatile components in peptic powder by gas chromatography–mass spectrometry and chemometric resolution

    Microsoft Academic Search

    Fan Gong; Yi-Zeng Liang; Hui Cui; Foo-Tim Chau; Benny Tsz-Pun Chan

    2001-01-01

    Gas chromatography–mass spectrometry (GC–MS) coupled with chemometric resolution upon two-dimensional data was proposed as a method for the analysis of volatile components in a traditional Chinese medicinal preparation peptic powder which contains Rhizoma Atractylodis, Pericarpium Citri Reticulatae, Cortex Magnoliae Officinalis and Radix Glycyrrhizae. Ninety-three components were separated and 65 of them were qualitatively and quantitatively analyzed which represented about 90.28%

  8. Laser desorption fast gas chromatography–Mass spectrometry in supersonic molecular beams

    Microsoft Academic Search

    Tzvi Shahar; Shai Dagan; Aviv Amirav

    1998-01-01

    A novel method for fast analysis is presented. It is based on laser desorption injection followed by fast gas chromatography-mass\\u000a spectrometry (GC-MS) in supersonic molecular beams. The sample was placed in an open air or purged laser desorption compartment,\\u000a held at atmospheric pressure and near room temperature conditions. Desorption was performed with a XeCl Excimer pulsed laser\\u000a with pulse energy

  9. Quantitative determination of amphetamines, cocaine, and opiates in human hair by gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    L Skender; V Kara?i?; I Br?i?; A Bagari?

    2002-01-01

    Hair of young subjects (N=36) suspected for drug abuse was analysed for morphine, codeine, heroin, 6-acetylmorphine, cocaine, methadone, amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA), and 3,4-methylenedioxyethylamphetamine (MDEA). The analysis of morphine, codeine, heroin, 6-acetylmorphine, cocaine, and methadone in hair included incubation in methanol, solid-phase extraction, derivatisation by the mixture of propionic acid anhydride and pyridine, and gas chromatography\\/mass spectrometry (GC\\/MS).

  10. Formation of dehydroalanine from mimosine and cysteine: artifacts in gas chromatography/mass spectrometry based metabolomics

    SciTech Connect

    Kim, Young-Mo; Metz, Thomas O.; Hu, Zeping; Wiedner, Susan D.; Kim, Jong Seo; Smith, Richard D.; Morgan, William F.; Zhang, Qibin

    2011-08-15

    Trimethylsilyation is a chemical derivatization procedure routinely applied in gas chromatography-mass spectrometry (GC-MS)-based metabolomics. In this report, through de novo structural elucidation and comparison with authentic standards, we demonstrate that mimosine can be completely converted into dehydroalanine and 3,4-dihydroxypyridine during the trimethylsilyating process. Similarly, dehydroalanine can be formed from derivatization of cysteine. This conversion is a potential interference in GC-MS-based global metabolomics, as well as in analysis of amino acids.

  11. Liquid chromatography/mass spectrometry based fingerprinting analysis and mass profiling of Euterpe oleracea (açaí) dietary supplement raw materials.

    PubMed

    Mulabagal, Vanisree; Calderón, Angela I

    2012-09-15

    Chemical fingerprinting and mass profiling methods to identify biologically active compounds in botanical dietary supplements is gaining much attention in recent years. Euterpe oleracea (açaí) has been reported to be rich in health-beneficial chemical constituents. We have developed LC/MS based fingerprinting and mass profiling methods to identify fatty acids, anthocyanins and non-anthocyanin polyphenols in three processed raw materials; non-organic açaí powder (ADSR-1), raw-organic açaí powder (ADSR-2) and freeze-dried açaí powder (ADSR-3) that are used in the preparation of botanical dietary supplements. For LC/MS analysis of fatty acids and non-anthocyanin polyphenols, the açaí samples were extracted sequentially with dichloromethane followed by methanol. To study fingerprinting analysis of anthocyanins, açaí samples were extracted with acidic methanol-water. The LC separation of fatty acids, non-anthocyanin polyphenols and anthocyanins in açaí raw materials was achieved using a C18 column with a gradient mobile phase consisting of solvents A (0.1% formic acid in water), and B (0.1% formic acid in methanol). MS experiments were carried out with negative and positive mode electrospray ionization. LC/MS analysis of dichloromethane extracts of (ADSR-1), (ADSR-2) and (ADSR-3) açaí powders have shown to contain fatty acids, ?-linolenic acid, linoleic acid, palmitic acid, and oleic acid. Whereas, the fingerprinting analysis of methanol extracts of ADSR-1, ADSR-2 and ADSR-3 led to the identification of phenolic acids, anthocyanin and non-anthocyanin polyphenols. The results from our study may be useful for the authentication and quality assessment of açaí dietary supplement raw materials. PMID:23107743

  12. Volatile profiles of sparkling wines obtained by three extraction methods and gas chromatography–mass spectrometry (GC–MS) analysis

    Microsoft Academic Search

    Joan Bosch-Fusté; Montserrat Riu-Aumatell; Josep M. Guadayol; Josep Caixach; Elvira López-Tamames; Susana Buxaderas

    2007-01-01

    Simultaneous distillation extraction (SDE) and closed-loop stripping analysis (CLSA) show great capacity for organic compound extraction. Here we used these techniques to obtain and characterize a wide range of volatile compounds from aged cava sparkling wine. We also explored the potential application of head space-solid phase micro extraction (HS-SPME) to determine the distinctive volatile compounds of aged cava as this

  13. Simultaneous analysis of pesticides from different chemical classes by using a derivatisation step and gas chromatography-mass spectrometry.

    PubMed

    Raeppel, Caroline; Nief, Marie; Fabritius, Marie; Racault, Lucie; Appenzeller, Brice M; Millet, Maurice

    2011-11-01

    This work presents a new method to analyse simultaneously by GC-MS 31 pesticides from different chemical classes (2,4 D, 2,4 MCPA, alphacypermethrin, bifenthrin, bromoxynil, buprofezin, carbaryl, carbofuran, clopyralid, cyprodinil, deltamethrin dicamba, dichlobenil, dichlorprop, diflufenican, diuron, fenoxaprop, flazasulfuron, fluroxypyr, ioxynil, isoxaben, mecoprop-P, myclobutanil, oryzalin, oxadiazon, picloram, tau-fluvalinate tebuconazole, triclopyr, trifluralin and trinexapac-p-ethyl). This GC-MS method will be applied to the analysis of passive samplers (Tenax(®) tubes and SPME fiber) used for the evaluation of the indoor and outdoor atmospheric contamination by non-agricultural pesticides. The method involves a derivatisation step for thermo-labile or polar pesticides. Different agents were tested and MtBSTFA (N-(t-butyldimethylsilyl)-N-methyltrifluoroacetamide), a sylilation agent producing very specific fragments [M-57], was retained. However, diuron could not be derivatised and the isocyanate product was used for identification and quantification. Pesticides which did not need a derivatisation step were not affected by the presence of the derivatisation agent and they could easily be analysed in mixture with derivatised pesticides. The method can be coupled to a thermal-desorption unit or to SPME extraction for a multiresidue analysis of various pesticides in atmospheric samples. PMID:21962330

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

    PubMed

    Myjavcová, Renáta; Marhol, Petr; K?en, Vladimír; Simánek, Vilím; Ulrichová, Jitka; Palíková, Irena; Papoušková, Barbora; Lemr, Karel; Bedná?, Petr

    2010-12-17

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

  15. Determination of boiling point of petrochemicals by gas chromatography-mass spectrometry and multivariate regression analysis of structural activity relationship.

    PubMed

    Fakayode, Sayo O; Mitchell, Breanna S; Pollard, David A

    2014-08-01

    Accurate understanding of analyte boiling points (BP) is of critical importance in gas chromatographic (GC) separation and crude oil refinery operation in petrochemical industries. This study reported the first combined use of GC separation and partial-least-square (PLS1) multivariate regression analysis of petrochemical structural activity relationship (SAR) for accurate BP determination of two commercially available (D3710 and MA VHP) calibration gas mix samples. The results of the BP determination using PLS1 multivariate regression were further compared with the results of traditional simulated distillation method of BP determination. The developed PLS1 regression was able to correctly predict analytes BP in D3710 and MA VHP calibration gas mix samples, with a root-mean-square-%-relative-error (RMS%RE) of 6.4%, and 10.8% respectively. In contrast, the overall RMS%RE of 32.9% and 40.4%, respectively obtained for BP determination in D3710 and MA VHP using a traditional simulated distillation method were approximately four times larger than the corresponding RMS%RE of BP prediction using MRA, demonstrating the better predictive ability of MRA. The reported method is rapid, robust, and promising, and can be potentially used routinely for fast analysis, pattern recognition, and analyte BP determination in petrochemical industries. PMID:24881546

  16. Improved high sensitivity analysis of polyphenols and their metabolites by nano-liquid chromatography-mass spectrometry.

    PubMed

    Wilson, Landon; Arabshahi, Ali; Simons, Brigitte; Prasain, Jeevan K; Barnes, Stephen

    2014-10-01

    This study was conducted to assess the value of a high resolution, high mass accuracy time-of-flight analyzer in combination with nanoliquid chromatography for the analysis of polyphenols and their metabolites. The goal was to create a method that utilizes small volumes of biological fluids and provides a significant improvement in sensitivity compared with existing methods. Accordingly, nanoLC-MS and nanoLC-pseudo-multiple reaction monitoring (MRM) methods were developed that had a lower limit of quantification of 0.5 nM for several polyphenols and were linear over 2-3 orders of magnitude (R(2)>0.999). Using urine samples, the ability to observe and quantify polyphenols in such a complex biological fluid depended on much narrower mass windows (0.050 amu or less) on a TOF analyzer than those used on a quadrupole analyzer (0.7 amu). Although a greater selectivity was possible with the low mass resolution of a triple quadrupole instrument using the MRM approach, for the daidzein metabolite O-DMA, a chromatographically resolvable second peak could only be substantially reduced by using a 0.01 amu mass window. The advantage of a TOF analyzer for product ion data is that the whole MSMS spectrum is collected at high mass accuracy and MRM experiments are conducted in silico after the analysis. PMID:24967696

  17. Analysis of iodide and iodate in Lake Mead, Nevada using a headspace derivatization gas chromatography-mass spectrometry.

    PubMed

    Dorman, James W; Steinberg, Spencer M

    2010-02-01

    We report here a derivatization headspace method for the analysis of inorganic iodine in water. Samples from Lake Mead, the Las Vegas Wash, and from Las Vegas tap water were examined. Lake Mead and the Las Vegas Wash contained a mixture of both iodide and iodate. The average concentration of total inorganic iodine (TII) for Lake Mead was approximately 90 nM with an iodide-to-iodate ratio of approximately 1. The TII concentration (approximately 160 nM) and the ratio of iodide to iodate were higher for the Las Vegas Wash (approximately 2). The TII concentration for tap water was close to that of Lake Mead (approximately 90 nM); however, tap water contained no detectable iodide as a result of ozonation and chlorine treatment which converts all of the iodide to iodate. PMID:19184627

  18. Multiresidue analysis of pesticides in soil by gas chromatography with nitrogen-phosphorus detection and gas chromatography mass spectrometry.

    PubMed

    Fenoll, José; Hellín, Pilar; Marín, Cristóbal; Martínez, Carmen M; Flores, Pilar

    2005-10-01

    A rapid multiresidue method for the simultaneous determination of 25 fungicides and insecticides in soil was developed. Soil samples are extracted by sonication with a water-acetonitrile mixture, and the pesticides are partitioned into dichloromethane. Final determination was made by gas chromatography (GC) with nitrogen-phosphorus detection (NPD). Confirmation analysis of pesticides was carried out by GC-MS in the selected ion monitoring (SIM) mode. The identification of compounds was based on retention time and on comparison of the primary and secondary ions. The average recovery by the GC-NPD method obtained for these compounds varied from 68.5% to 112.1% with a relative standard deviation between 1.8% and 6.2%. The GC-NPD method presents good linearity over the range assayed 50-2000 microg/L, and the detection limit for the pesticides studied varied from 0.1 to 10.4 microg/kg. The proposed method was used to determine pesticide levels in soil samples from experimental greenhouse pepper cultivation. PMID:16190613

  19. Predication of Japanese green tea (Sen-cha) ranking by volatile profiling using gas chromatography mass spectrometry and multivariate analysis.

    PubMed

    Jumtee, Kanokwan; Komura, Hajime; Bamba, Takeshi; Fukusaki, Eiichiro

    2011-09-01

    The sensory quality ranking of Japanese green tea (Sen-cha) was evaluated and predicted using volatile profiling and multivariate data analyses. The volatile constituents were extracted from tea infusion using vacuum hydrodistillation and analyzed using GC/MS. A quality of green tea could be discriminated to a high or low grade regarding the volatile profile by partial least squares discriminant analysis (PLS-DA). A quality ranking predictive model was developed from the relationship between subjective attributes (sensory quality ranking) and objective attributes (volatile profile) using partial least squares projections to latent structures together with the preprocessing filtering technique, orthogonal signal correction (OSC). Several volatile compounds highly contributed to model prediction were identified as various odor-active compounds, including geraniol, indole, linalool, cis-jasmone, dihydroactinidiolide, 6-chloroindole, methyl jasmonate, coumarin, trans-geranylacetone, linalool oxides, 5,6-epoxy-?-ionone, phytol, and phenylethyl alcohol. The whole fingerprints of these volatile compounds could be possible markers for the overall quality evaluation of green tea beverage. PMID:21664180

  20. Lipidome and metabolome analysis of fresh tobacco leaves in different geographical regions using liquid chromatography-mass spectrometry.

    PubMed

    Li, Lili; Lu, Xin; Zhao, Jieyu; Zhang, Junjie; Zhao, Yanni; Zhao, Chunxia; Xu, Guowang

    2015-07-01

    The combination of the lipidome and the metabolome can provide much more information in plant metabolomics studies. A method for the simultaneous extraction of the lipidome and the metabolome of fresh tobacco leaves was developed. Method validation was performed on the basis of the optimal ratio of methanol to methyl tert-butyl ether to water (37:45:68) from the design of experiments. Good repeatability was obtained. We found that 92.2 % and 91.6 % of the peaks for the lipidome and the metabolome were within a relative standard deviation of 20 %, accounting for 94.6 % and 94.6 % of the total abundance, respectively. The intraday and interday precisions were also satisfactory. A total of 230 metabolites, including 129 lipids, were identified. Significant differences were found in lipidomic and metabolomic profiles of fresh tobacco leaves in different geographical regions. Highly unsaturated galactolipids, phosphatidylethanolamines, predominant phosphatidylcholines, most of the polyphenols, amino acids, and polyamines had a higher content in Yunnan province, and low-unsaturation-degree galactolipids, triacylglycerols, glucosylceramides with trihydroxy long-chain bases, acylated sterol glucosides, and some organic acids were more abundant in Henan province. Correlation analysis between differential metabolites and climatic factors indicated the vital importance of temperature. The fatty acid unsaturation degree of galactolipids could be influenced by temperature. Accumulation of polyphenols and decreases in the ratios of stigmasterols to sitosterols and glucosylstigmasterols to glucosylsitosterols were also correlated with lower temperature in Yunnan province. Furthermore, lipids were more sensitive to climatic variations than other metabolites. Graphical Abstract Lipidomic and metabolomic profiles of tobacco in different regions. PMID:25701418

  1. Pitfalls encountered during quantitative determination of 3-alkyl-2-methoxypyrazines in grape must and wine using gas chromatography-mass spectrometry with stable isotope dilution analysis. Comprehensive two-dimensional gas chromatography-mass spectrometry and on-line liquid chromatography-multidimensional gas chromatography-mass spectrometry as potential loopholes.

    PubMed

    Schmarr, Hans-Georg; Ganss, Sebastian; Koschinski, Stefan; Fischer, Ulrich; Riehle, Carmen; Kinnart, Julian; Potouridis, Theodoros; Kutyrev, Maria

    2010-10-22

    The analysis of 3-alkyl-2-methoxypyrazines in Vitis vinifera grape must or wine at the low nanogram per liter level failed in several situations when applying a one-dimensional gas chromatographic analysis with mass spectrometric detection (GC-MS). Sample preparation methods such as headspace solid phase microextraction or solid phase extraction were convenient procedures, however lacking extraction selectivity for complex matrices. Analysis by comprehensive two-dimensional gas chromatography with mass spectrometric detection clearly demonstrated the potential for co-elution in such matrices and the risk for erroneous results when applying one-dimensional GC-MS. In one example, matrix problems would have been a challenge even for a comprehensive two-dimensional chromatographic approach with MS detection (GC×GC-MS). A solution to matrix problems was found by protonating the 3-alkyl-2-methoxypyrazines in acidic pH and sample clean-up using solid phase extraction with a mixed-mode polymeric cation-exchange sorbent. Quantification was performed by a stable isotope dilution assay, following analysis by on-line coupled high performance liquid chromatography with multidimensional gas chromatography and detection with mass spectrometry (on-line LC-MDGC-MS). This new approach allowed trace-level analysis of 3-alkyl-2-methoxypyrazines in grape musts and wines and is described for V. vinifera Sauvignon blanc, following 3-alkyl-2-methoxypyrazines concentrations during ripening and in the processed wines. PMID:20637469

  2. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory : determination of polycyclic aromatic hydrocarbon compounds in sediment by gas chromatography/mass spectrometry

    USGS Publications Warehouse

    Olson, Mary C.; Iverson, Jana L.; Furlong, Edward T.; Schroeder, Michael P.

    2004-01-01

    A method for the determination of 28 polycyclic aromatic hydrocarbons (PAHs) and 25 alkylated PAH homolog groups in sediment samples is described. The compounds are extracted from sediment by solvent extraction, followed by partial isolation using high-performance gel permeation chromatography. The compounds are identified and uantitated using capillary-column gas chromatography/mass spectrometry. The report presents performance data for full-scan ion monitoring. Method detection limits in laboratory reagent matrix samples range from 1.3 to 5.1 micrograms per kilogram for the 28 PAHs. The 25 groups of alkylated PAHs are homologs of five groups of isomeric parent PAHs. Because of the lack of authentic standards, these homologs are reported semiquantitatively using a response factor from a parent PAH or a specific alkylated PAH. Precision data for the alkylated PAH homologs are presented using two different standard reference manuals produced by the National Institute of Standards and Technology: SRM 1941b and SRM 1944. The percent relative standard deviations for identified alkylated PAH homolog groups ranged from 1.55 to 6.98 for SRM 1941b and from 6.11 to 12.0 for SRM 1944. Homolog group concentrations reported under this method include the concentrations of individually identified compounds that are members of the group. Organochlorine (OC) pesticides--including toxaphene, polychlorinated biphenyls (PCBs), and organophosphate (OP) pesticides--can be isolated simultaneously using this method. In brief, sediment samples are centrifuged to remove excess water and extracted overnight with dichloromethan (95 percent) and methanol (5 percent). The extract is concentrated and then filtered through a 0.2-micrometer polytetrafluoroethylene syringe filter. The PAH fraction is isolated by quantitatively injecting an aliquot of sample onto two polystyrene-divinylbenzene gel-permeation chromatographic columns connected in series. The compounds are eluted with dichloromethane, a PAH fraction is collected, and a portion of the coextracted interferences, including elemental sulfur, is separated and discarded. The extract is solvent exchanged, the volume is reduced, and internal standard is added. Sample analysis is completed using a gas chromatograph/mass spectrometer and full-scan acquisition.

  3. Statistical Assessment of Time and Mass Alignment Quality in Liquid Chromatography-Mass Spectrometry 

    E-print Network

    Velando, Isaac

    2011-01-11

    This research evaluated the efficacy of an alignment quality algorithm and follows its development. Proteomics research frequently involves liquid chromatography-mass spectrometry (LC-MS) methods for data collection. To correct for systematic errors...

  4. 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. PMID:833106

  5. CHARACTERIZATION OF ORGANICS IN TANNERY EFFLUENTS BY LIQUID CHROMATOGRAPHY MASS SPECTROMETRY

    EPA Science Inventory

    Combined high performance liquid chromatography mass spectrometry using a moving belt interface has been used to study extracts from five tannery and leather finishing industry discharges. Liquid chromatographic separation was performed with a Zorbax CN column using a normal phas...

  6. Measuring Deuterium Enrichment of Glucose Hydrogen Atoms by Gas Chromatography/Mass Spectrometry

    E-print Network

    Antoniewicz, Maciek R.

    We developed a simple and accurate method for determining deuterium enrichment of glucose hydrogen atoms by electron impact gas chromatography mass spectrometry (GC/MS). First, we prepared 18 derivatives of glucose and ...

  7. Improvement of a headspace solid phase microextraction-gas chromatography/mass spectrometry method for the analysis of wheat bread volatile compounds.

    PubMed

    Raffo, Antonio; Carcea, Marina; Castagna, Claudia; Magrì, Andrea

    2015-08-01

    An improved method based on headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME/GC-MS) was proposed for the semi-quantitative determination of wheat bread volatile compounds isolated from both whole slice and crust samples. A DVB/CAR/PDMS fibre was used to extract volatiles from the headspace of a bread powdered sample dispersed in a sodium chloride (20%) aqueous solution and kept for 60min at 50°C under controlled stirring. Thirty-nine out of all the extracted volatiles were fully identified, whereas for 95 other volatiles a tentative identification was proposed, to give a complete as possible profile of wheat bread volatile compounds. The use of an array of ten structurally and physicochemically similar internal standards allowed to markedly improve method precision with respect to previous HS-SPME/GC-MS methods for bread volatiles. Good linearity of the method was verified for a selection of volatiles from several chemical groups by calibration with matrix-matched extraction solutions. This simple, rapid, precise and sensitive method could represent a valuable tool to obtain semi-quantitative information when investigating the influence of technological factors on volatiles formation in wheat bread and other bakery products. PMID:26118802

  8. Metabonomic analysis of quercetin against the toxicity of chronic exposure to low-level dichlorvos in rats via ultra-performance liquid chromatography-mass spectrometry.

    PubMed

    Wang, Hong; Li, Sifan; Qi, Lei; Xu, Wei; Zeng, Yan; Hou, Yurong; Zhao, Xiujuan; Sun, Changhao

    2014-03-01

    This study aims to determine whether quercetin elicits a protective effect against the toxicity of chronic exposure to low-level DDVP using metabonomic technology. Rats were randomly assigned into the control, DDVP-treated, quercetin-treated, and quercetin plus DDVP-treated groups. DDVP and quercetin were given to rats daily via drinking water and gavage respectively for 90 days. Eighteen metabolites, including the biomarkers of DDVP exposure (dimethyl phosphate, DMP) and quercetin exposure (quercetin and isorhamnetina), were identified from the metabonomic profiles of rat urine using ultra-performance liquid chromatography-mass spectrometry. Compared with the control group, the DDVP-treated group showed statistically significantly increased intensities of indoxyl sulfate, estrone sulfate, cholic acid, deoxycholic acid, p-cresol, p-cresol sulfate, and orotic acid but decreased intensities of suberic acid, citric acid, sebacic acid, hippuric acid, taurine, phosphocreatine, 3-hydroxyanthranilic acid, and kynurenic acid. The tendency of the aforesaid metabolites to change was significantly ameliorated in the quercetin (50mg/kg·bw) plus DDVP (7.2mg/kg·bw)-treated group compared with the DDVP-treated group. However, the levels of these metabolites in the quercetin plus DDVP-treated groups were still significantly different from those of the control group. These results indicate that quercetin has a partial protective effect on DDVP-induced toxicity. PMID:24374570

  9. Identification of major histocompatibility complex-regulated body odorants by statistical analysis of a comparative gas chromatography/mass spectrometry experiment.

    PubMed

    Willse, Alan; Belcher, Anne M; Preti, George; Wahl, Jon H; Thresher, Miranda; Yang, Peter; Yamazaki, Kunio; Beauchamp, Gary K

    2005-04-15

    This paper examines the application of gas chromatography/mass spectrometry (GC/MS) in a comparative experiment to identify volatile compounds from urine that differ in concentration between two groups of inbred mice. A complex mixture might comprise several hundred or even thousands of volatile compounds. Because their number and location in a chromatogram are generally unknown, and because components overlap in populous chromatograms, the statistical problems offer significant challenges beyond traditional two-group screening procedures. We describe a statistical procedure to compare two-dimensional GC/MS profiles between groups, which entails (1) signal processing, baseline correction, and peak detection in single ion chromatograms; (2) aligning chromatograms in time; (3) normalizing differences in overall signal intensities; and (4) detecting chromatographic regions that differ between groups. In an application to chemosignaling, we detect differences in GC/MS chromatograms of ether-extracted urine collected from two inbred groups of mice that differ only in genes of the major histocompatibility complex (MHC). Several dozen MHC-regulated compounds are found, including two known mouse pheromones, 2,5-dimethylpyrazine and 2-sec-butyl-4,5-dihydrothiazole. PMID:15828767

  10. [Applications of multi-micro-volume pressure-assisted derivatization reaction device for analysis of polar heterocyclic aromatic amines by gas chromatography-mass spectrometry].

    PubMed

    Wang, Yiru; Chen, Fangxiang; Shi, Yamei; Tan, Connieal; Chen, Xi

    2013-01-01

    A multi-micro-volume pressure-assisted derivatization reaction device has been designed and made for the silylation derivatization of polar heterocyclic aromatic amines by N-(tert-butyldimethylsilyl )-N-methyl-trifluoroacetamide (MTBSTFA) with 1% catalyst tert-butyldimethylchlorosilane (TBDMCS) at a high temperature. The tert-butyldimethylsilyl derivatives then could be automatically analyzed by gas chromatography-mass spectrometry. Using the pressure-assisted device, the silylation reaction may occur at a temperature higher than the boiling points of the reagents, and several micro-volume samples can be simultaneously pretreated in the same device to shorten the sample-preparation time and to improve the repeatability. The derivatization conditions including the headspace volume of the vial, the evaporative surface area of the reagent, derivatization temperature and time have been discussed for the use of the pressure-assisted device. The experimental results proved that the device is an effective way for the simultaneous derivatization of several micro-volume samples at a high temperature. Compared with a common device, the derivative amounts were obviously increased when using the pressure-assisted device at 90 degrees C. Quantitative derivatization can be achieved even at 150 degrees C while there was no common device could be applied at such a high temperature due to the heavy losses of reagents by evaporation. However, no obviously higher reaction speed has been observed in such a circumstance with a higher temperature and a higher pressure using the pressure-assisted device. PMID:23667982

  11. Detection of chlorpyrifos-ethyl (Dursban) and its metabolites in urine samples using immunoassays with confirmation by gas chromatography/mass spectrometry

    E-print Network

    Clewis, Suenda Beth

    1995-01-01

    and agricultural purposes because of their relatively low toxicity. Exposure to chlorpyrifos-ethyl is commonly determined by measuring cholinesterase inhibition. This method requires blood. sample analysis via gas chromatography/mass spectrometry (GC/MS), and can...

  12. Accurate analysis of polycyclic aromatic hydrocarbons (PAHs) and alkylated PAHs homologs in crude oil for improving the gas chromatography/mass spectrometry performance.

    PubMed

    Zhao, Yue; Hong, Bo; Fan, Yuqing; Wen, Mei; Han, Xue

    2014-02-01

    The common gas chromatography/mass spectrometry (GC/MS) approaches such as selective ion monitoring (SIM) or single ion extraction (SIE) from full scan data produce the error (over- or underestimation) estimates for the high level alkylated polycyclic aromatic hydrocarbons (PAHs). In order to rectify the error, the alkylated PAHs in the crude oil samples are quantified by deeply investigating the existing full scan data of 1D GC/MS, instead of resuming with the complex and inaccessible equipments (multidimensional gas chromatography or mass spectrometry). The aim of this study is to provide the detailed qualitative and quantitative basis data (confirming ions, relative abundance, retention indices, and area counts) of the high level alkylated PAHs by a comprehensive three-step method: (1) the potential confirming ions per isomer are selected by exploring the multiple fragment patterns formation mechanism; (2) the reasonable confirming ions are estimated by comparing extracted ion chromatography (EIC) of the potential confirming ions; (3) after deconvolution, composite chromatograms of the reasonable confirming ions illustrate the basis data by assigning peaks for target PAHs definitively. The validation data, resulting concentrations and diagnostic ratios for each homolog are compared with those obtained from SIM. The experimental data demonstrate that significant inaccurate identifications and concentration estimates are obtained when SIM mode is used for C4 Naphthalene (C4 N), C3 Phenanthrene (C3 P), C4 Phenanthrene (C4 P), C3 Dibenzothiophene (C3 D), C3 Fluorene (C3 F), C2-4 Chrysene (C2-4 C) and C1 Fluoranthene (C1 Flt). This study evaluates the usefulness of the previous fragmentation patterns, and confirms compound presence by GC/MS using the different spectral deconvolution software. This approach is developed as a broad screen for environmental samples (including petrol, diesel fuel and coal tar), with only the crude oil results being presented here. PMID:24229786

  13. Rapid white truffle headspace analysis by proton transfer reaction mass spectrometry and comparison with solid-phase microextraction coupled with gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    Eugenio Aprea; Franco Biasioli; Silvia Carlin; Giuseppe Versini; TD Mark; Flavia Gasperi

    2007-01-01

    The gastronomic relevance and high price of white truffle are related mainly to its unique aroma. Here we evaluate, for the first time, the possibility of characterizing in a rapid and non-destructive way the aroma of white truffles based on proton transfer reaction mass spectrometry {(PTR-MS).} We indicate that anonymous {PTR-MS} fingerprinting allows sample classification and we also compare qualitatively

  14. Analysis of plasticizers and synthetic musks in cosmetic and personal care products by matrix solid-phase dispersion gas chromatography-mass spectrometry.

    PubMed

    Llompart, Maria; Celeiro, Maria; Pablo Lamas, J; Sanchez-Prado, Lucia; Lores, Marta; Garcia-Jares, Carmen

    2013-06-01

    Matrix solid-phase dispersion (MSPD) and gas chromatography-mass spectrometry were used for the rapid determination of 18 plasticizers (phthalates and adipates), 7 polycyclic musks and 5 nitromusks, which makes a total of 30 targets, in both rinse-off and leave-on cosmetic formulations. The MSPD method was miniaturized and customized to avoid or minimize risks of phthalate contamination and to reduce residues and costs. The amount of sample and extraction solvent employed were 0.1g and 1mL, respectively. The procedure was optimized by means of an experimental design and under the optima conditions it showed satisfactory linearity, repeatability and intermediate precision. LOQs were, in general, in the low ngg(-1), and recoveries were quantitative for all the 18 plasticizers and the 12 fragrances. Twenty-six cosmetic products such as creams, emulsions, lotions, gels for the skin, bath and shower preparations, deodorants, hair-setting, hair-cleansing and hair-conditioning products, shaving products, and sunbathing products, were analyzed. Twenty-five out of thirty targets were detected in the samples. The most frequently found compounds were galaxolide and tonalide reaching concentrations above 0.1% (1000?gg(-1)), and diethyl phthalate (between 0.7 and 357?gg(-1)). The presence of banned substances (Regulation (EC) No. 1223/2009) such as dibutyl phthalate, diisobutyl phthalate, dimethoxyethyl phthalate, benzylbutyl phthalate, diethylhexyl phthalate, diisopentyl phthalate and dipentyl phthalate, musk ambrette and musk tibetene was confirmed in sixteen of the twenty-six personal care products (62%). PMID:23622555

  15. Optimization of large volume injection-programmable temperature vaporization-gas chromatography-mass spectrometry analysis for the determination of estrogenic compounds in environmental samples.

    PubMed

    Vallejo, A; Fernández, L A; Olivares, M; Prieto, A; Etxebarria, N; Usobiaga, A; Zuloaga, O

    2010-12-24

    Large volume injection-programmable temperature vaporization-gas chromatography-mass spectrometry (LVI-PTV-GC-MS) was optimized for the determination of estrone (E1), 17?-estradiol (E2), 17?-ethynyl estradiol (EE2), mestranol (MeEE2) and estriol (E3) for their determination in environmental samples (estuarine water, wastewater, fish bile and fish homogenate) after derivatization with 25 ?L (BSTFA+1% TMCS) and 125 ?L of pyridine. Experimental designs such as Plackett-Burman (PBD) and central composite designs (CCDs) were used to optimize the LVI-PTV variables (cryo-focusing temperature, vent time, vent flow, vent pressure, injection volume, purge flow to split vent, splitless time and injection speed). Optimized conditions were as follows: 45 ?L of n-hexane extract are injected at 60°C and 6 ?L/s with a vent flow and a vent pressure of 50 mL/min and 7.7 psi, respectively, during 5 min; then the split valve is closed for 1.5 min and afterwards the injector is cleaned at 100 mL/min before the next injection. The method was applied to the determination of estrogenic compounds in environmental samples such as estuarine water, wastewater, and fish homogenate and bile. Limits of detection (0.04-0.15 ng/L for water samples, 0.04-0.67 ng/g for fish bile and 0.1-7.5 ng for fish homogenate) obtained were approx. ten times lower than those obtained by means of a common split/splitless inlet. PMID:21092978

  16. Development of stir-bar sorptive extraction-thermal desorption-gas chromatography-mass spectrometry for the analysis of musks in vegetables and amended soils.

    PubMed

    Aguirre, Josu; Bizkarguenaga, Ekhiñe; Iparraguirre, Arantza; Fernández, Luis Ángel; Zuloaga, Olatz; Prieto, Ailette

    2014-02-17

    The aim of this study was to develop a sensitive and environment-friendly method based on stir-bar sorptive extraction (SBSE) followed by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) to determine 8 synthetic musks (musk ambrette, musk ketone, celestolide, tonalide, galaxolide, phantolide, traseolide, and cashmeran) in vegetables (lettuce, carrot, and pepper) and amended soil samples. In a first step sorptive extraction was studied both in the headspace (HSSE) and in the immerse mode (SBSE). The best results were obtained in the immersion mode which was further studied. The influence of the main factors: methanol (20%) and NaCl addition (0%), extraction temperature (40°C) and time (180 min), extraction solvent volume (9 mL) and stirring rate (600 rpm) on the efficiency of SBSE was evaluated by means of experimental designs. In the case of TD, desorption time (10 min), desorption temperature (300°C), cryo-focusing temperature (-30°C), vent flow (75 mL/min) and vent pressure (7.2 psi) were studied using both a fractioned factorial design and a central composite design (CCD). The method was validated in terms of apparent recoveries (AR%), method detection limits (MDLs) and precision at two different concentration levels. Although quantification using instrumental calibration rendered odd results in most of the cases, satisfactory recoveries (74-126%) were obtained in the case of matrix-matched calibration approach for all of the analytes and matrices studied at the two concentration levels evaluated. MDLs in the range of 0.01-0.8 ng/g and 0.01-1.1 ng/g were obtained for vegetables and amended soil samples, respectively. RSD values within 1-23% were obtained for all the analytes and matrices. Finally, the method was applied to the determination of musks in vegetable and amended soil samples. PMID:24491767

  17. Quality control of sweet medicines based on gas chromatography-mass spectrometry.

    PubMed

    Lv, Guangping; Hu, Dejun; Zhao, Jing; Li, Shaoping

    2015-01-01

    Sweet medicines are a relatively untapped source of new drugs. Their biological activities are closely correlated to their chemical characteristics. However, accurately defining the chemical characteristics of glycans is a challenge due to their chemical heterogeneity and diversity. Gas chromatography-mass spectrometry (GC-MS) is an excellent technique for the analysis of glycans even though the preparation of adequate derivatives is necessary. We reviewed and discussed the most important methodologies currently used for glycan analysis in sweet medicines based on GC-MS, including the derivatization for monosaccharide analysis, hydrolysis methods for polysaccharide analysis, glycosidic linkage analysis based on methylation, and pyrolysis gas chromatography in carbohydrate analysis. Finally a strategy for quality control of sweet medicines based on quantification analysis is proposed. PMID:25994060

  18. Rapid white truffle headspace analysis by proton transfer reaction mass spectrometry and comparison with solid-phase microextraction coupled with gas chromatography/mass spectrometry.

    PubMed

    Aprea, Eugenio; Biasioli, Franco; Carlin, Silvia; Versini, Giuseppe; Märk, Tilmann D; Gasperi, Flavia

    2007-01-01

    The gastronomic relevance and high price of white truffle are related mainly to its unique aroma. Here we evaluate, for the first time, the possibility of characterizing in a rapid and non-destructive way the aroma of white truffles based on proton transfer reaction mass spectrometry (PTR-MS). We indicate that anonymous PTR-MS fingerprinting allows sample classification and we also compare qualitatively and quantitatively PTR-MS data with measurements made by solid-phase microextraction gas chromatography (SPME-GC) of the same samples under the same conditions. PTR-MS fragmentation data of truffle-relevant compounds are also published here for the first time. Most of the sulfur-containing compounds detected by GC and relevant for white truffle aroma have a high positive correlation with single PTR-MS peaks. Our work indicates that, after preliminary comparison with GC data, PTR-MS is a new tool for the rapid, quantitative and non-invasive characterization of white truffle by direct headspace injection without any pre-concentration. PMID:17639568

  19. Quantitative analysis of polar lipids in the nanoliter level of rat serum by liquid chromatography/mass spectrometry/mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polar lipids in serum, including lysophospholipids (LPLs) and free fatty acids (FFAs), have a broad range of biological activities and require a suitable method for their quantitative analysis. Conventional methods use multistep procedures to simultaneously purify and analyze polar lipids and non-po...

  20. Comparison of the possibilities of gas chromatography-mass spectrometry and tandem mass spectrometry systems for the analysis of anabolics in biological material.

    PubMed

    De Brabander, H F; Batjoens, P; Courtheyn, D; Vercammen, J; De Wasch, K

    1996-10-25

    Chromatographic techniques such as GC-MS play a most important role in modern multi-residue analysis of anabolic steroids. The major difference between GC-MS apparatus from different manufacturers is the way of detection and recording. Most apparatus use selected-ion monitoring (SIM) for the determination of low concentrations. Systems based on ion trap technology record in full-scan to even picogram concentrations using a computer algorithm to compare the most important peaks of the mass spectrum of the unknown to those of the standard. In this investigation the possibilities of ion trap GC-MS and the recently released GCQ MS and MS2 for the analysis of anabolics in biological material are compared. PMID:8938384

  1. Effectiveness of isotopically labelled and non-isotopically labelled internal standards in the gas chromatography/mass spectrometry analysis of sulfur compounds in wines: use of a statistically based matrix comprehensive approach.

    PubMed

    Lavagnini, Irma; Fedrizzi, Bruno; Versini, Giuseppe; Magno, Franco

    2009-04-01

    The effectiveness of isotopically and non-isotopically labelled internal standards in reducing matrix-induced effects is evaluated. The question is addressed in the quantitative analysis by gas chromatography/mass spectrometry (GC/MS) of dimethyl sulphide, chosen as a typical example of volatile sulphur compounds, in wine matrices. When matrix/run effects are not cancelled out the use of a variance component model (VCM) to handle the linear calibrations obtained by regression technique is successful. The method implies the estimation of an overall calibration straight line, which properly takes into account the uncertainty due to different matrices, the calibration run and the measurement error, making the use of an isotopically labelled internal standard not necessary. The obtained results show that the benefits of lowering times and costs for routine analyses compensate for the small increase in uncertainty in the concentration values obtained in the regression analysis and the slight increase in the detection limit. PMID:19291680

  2. Trace analysis of total naphthenic acids in aqueous environmental matrices by liquid chromatography/mass spectrometry-quadrupole time of flight mass spectrometry direct injection.

    PubMed

    Brunswick, Pamela; Shang, Dayue; van Aggelen, Graham; Hindle, Ralph; Hewitt, L Mark; Frank, Richard A; Haberl, Maxine; Kim, Marcus

    2015-07-31

    A rapid and sensitive liquid chromatography quadrupole time of flight method has been established for the determination of total naphthenic acid concentrations in aqueous samples. This is the first methodology that has been adopted for routine, high resolution, high throughput analysis of total naphthenic acids at trace levels in unprocessed samples. A calibration range from 0.02 to 1.0?gmL(-1) total Merichem naphthenic acids was validated and demonstrated excellent accuracy (97-111% recovery) and precision (1.9% RSD at 0.02?gmL(-1)). Quantitative validation was also demonstrated in a non-commercial oil sands process water (OSPW) acid extractable organics (AEOs) fraction containing a higher percentage of polycarboxylic acid isomers than the Merichem technical mix. The chromatographic method showed good calibration linearity of ?0.999 RSQ to 0.005?gmL(-1) total naphthenic acids with a precision <3.1% RSD and a calculated detection limit of 0.0004?gmL(-1) employing Merichem technical mix reference material. The method is well suited to monitoring naturally occurring and industrially derived naphthenic acids (and other AEOs) present in surface and ground waters in the vicinity of mining developments. The advantage of the current method is its direct application to unprocessed environmental samples and to examine natural naphthenic acid isomer profiles. It is noted that where the isomer profile of samples differs from that of the reference material, results should be considered semi-quantitative due to the lack of matching isomer content. The fingerprint profile of naphthenic acids is known to be transitory during aging and the present method has the ability to adapt to monitoring of these changes in naphthenic acid content. The method's total ion scan approach allows for data previously collected to be examined retrospectively for specific analyte mass ions of interest. A list of potential naphthenic acid isomers that decrease in response with aging is proposed and a quantitative assay of an adamantane carboxylic acid is reported. PMID:26074097

  3. Chlorinated hydrocarbons in the atmosphere - Analysis at the parts-per-trillion level by GC-MS. [Gas Chromatography-Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Tyson, B. J.

    1975-01-01

    The propellant gases (Freons) used in aerosol spray cans can diffuse into the earth's upper atmosphere where they can react with the unfiltered ultraviolet radiation from the sun to reduce the earth's protective ozone layer. These Freons have been identified commonly by gas chromatography. Mass spectrometer data confirm other reports on the widespread concentrations of the Freons in the troposphere and demonstrate the presence of Freon 113 which has not been previously identified.

  4. Derivatization of pinacolyl alcohol with phenyldimethylchlorosilane for enhanced detection by gas chromatography-mass spectrometry.

    PubMed

    Albo, Rebecca L F; Valdez, Carlos A; Leif, Roald N; Mulcahy, Heather A; Koester, Carolyn

    2014-08-01

    A derivatization procedure for the qualitative gas chromatography-mass spectrometry (GC-MS) analysis of pinacolyl alcohol (PA) that employs phenyldimethylchlorosilane (PhDMClS) and the promoter N-methylimidazole is described. While PA, underivatized, can be detected using conventional gas chromatographic methods, its polarity and low boiling point make its detection in complex matrices challenging. The silylation procedure described herein generates a PA-derivative exhibiting an increased on-column retention time, thus shifting its GC-MS signal away from commonly encountered, volatile, interfering analytes. Derivatized PA could be distinguished from other PhDMClS-derivatized isomeric alcohols by its unique retention time and mass spectrum. The derivatization was demonstrated to perform well in the GC-MS analysis and identification of PA in samples from Proficiency Tests administered by the Organisation for the Prohibition of Chemical Weapons (OPCW). PMID:24481624

  5. Independent evaluation of a commercial deconvolution reporting software for gas chromatography mass spectrometry analysis of pesticide residues in fruits and vegetables.

    PubMed

    Norli, Hans Ragnar; Christiansen, Agnethe; Holen, Børge

    2010-03-26

    The gas chromatography mass spectrometry (GC-MS) deconvolution reporting software (DRS) from Agilent Technologies has been evaluated for its ability as a screening tool to detect a large number of pesticides in incurred and fortified samples extracted with acetone/dichloromethane/light petroleum (Mini-Luke method). The detection of pesticides is based on fixed retention times using retention time locking (RTL) and full scan mass spectral comparison with a partly customer built automated mass spectral deconvolution and identification system (AMDIS) database. The GC-MS was equipped with a programmable temperature vaporising (PTV) injector system which enables more sample to be injected. In a blind study of 52 real samples a total number of 158 incurred pesticides were found. In addition to the 85 pesticides found by manual interpretation of GC-NPD/ECD chromatograms, the DRS revealed 73 more pesticides (+46%). The DRS system also shows its potential to discover pesticides which are normally not searched for (EPN in long beans from Thailand). A spiking experiment was performed to blank matrices of apple, orange and lettuce with 177 different pesticides at concentration levels 0.02 and 0.1 mg/kg. The samples were analysed on GC-MS full scan and the AMDIS match factor was used as a mass spectral quality criterion. The threshold level of the AMDIS match factor was set at 20 to eliminate most of the false positives. AMDIS match factors from 20 up to 69 are regarded only as indication of a positive hit and must be followed by manual interpretation. Pesticides giving AMDIS match factors at > or = 70 are regarded as identified. To simplify and decrease the large amount of data generated at each concentration level, the AMDIS match factors > or = 20 was averaged (mean AMF) for each pesticide including the commodities and their replicates. Among 177 different pesticides spiked at 0.02 and 0.1 mg/kg level, the percentage of mean AMF values > or = 70 were 23% and 80%, respectively. For 531 individual detections of pesticides (177 pesticides x 3 replicates) giving AMDIS match factor 20 in apple, orange and lettuce, the detection rates at 0.02 mg/kg were 71%, 63% and 72%, respectively. For the 0.1 mg/kg level the detection rates were 89%, 85% and 89%, respectively. In real samples some manual interpretation must be performed in addition. However, screening by GC-MS/DRS is about 5-10 times faster compared to screening with GC-NPD/ECD because the time used for manual interpretation is much shorter and there is no need for re-injection on GC-MS for the identification of suspect peaks found on GC-NPD/ECD. PMID:20172528

  6. Microextraction with polyethersulfone for bisphenol-A, alkylphenols and hormones determination in water samples by means of gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry analysis.

    PubMed

    Ros, O; Vallejo, A; Blanco-Zubiaguirre, L; Olivares, M; Delgado, A; Etxebarria, N; Prieto, A

    2015-03-01

    In the present work, the suitability of polyethersulfone (PES) tube was assessed for the simultaneous sorptive microextraction of commonly found endocrine disrupting compounds in natural waters such as bisphenol-A (BPA), nonylphenol technical mixture (NP mix), 4-tert-octylphenol (4tOP), 4-n-octylphenol (4-nOP), 17?-estradiol (E2) and 17?-ethynilestradiol (EE2). After the concentration of target compounds in the PES polymer, the analytes were recovered soaking the polymer with a suitable solvent (ethyl acetate or methanol), derivatized using N,O-bis(trimethylsilyl)trifluoroacetamide with 1% of trimethylchlorosilane (BSTFA+1% TMCS) and determined by gas chromatography-mass spectrometry (GC-MS). The analysis was also performed without derivatization step by means of liquid chromatography-tandem mass spectrometry (LC-MS/MS). Extraction parameters (addition of MeOH, ionic strength, extraction speed and time and desorption time) were evaluated and the optimum conditions were fixed as follows: 150 mL water samples containing a 10% (w/v) of sodium chloride and using 5 tubular PES sorbent fibers (1.5 cm length×0.7 mm o.d.). Equilibrium conditions were achieved after 9 h, with absolute extraction efficiencies ranging from 27 to 56%. On the whole, good apparent recoveries were achieved (68-103% and 81-122% for GC-MS and LC-MS/MS, respectively) using deuterated analogues as surrogates. Achieved quantification limits (LOQs) varied between 2-154 ng/L and 2-63 ng/L for all the compounds using GC-MS and LC-MS/MS, respectively. The effect of organic matter was evaluated previous to apply the final method to the analysis of estuarine and wastewater real samples. The comparison of both methods showed that overall, PES-LC-MS/MS provided shorter sample preparation time and better LODs, but PES-silylation-GC-MS allowed the simultaneous determination of all the studied compounds with adequate repeatability and accuracy. PMID:25618664

  7. Gas chromatography-mass spectrometry method for determination of phenylalanine and tyrosine in neonatal blood spots.

    PubMed

    Deng, Chunhui; Deng, Yonghui; Wang, Bin; Yang, Xiuhan

    2002-11-25

    In this paper we developed a simple, rapid and sensitive method for the quantitative analysis of phenylalanine (Phe) and tyrosine (Tyr) in dried blood spots of newborns by gas chromatography-mass spectrometry (GC-MS). Phe and Tyr in blood samples were reacted with N-methyl-N-(tert.-butyldimethylsilyl)trifluoroacetamide at 120 degrees C for 30 min and their corresponding single derivatives were obtained. Phe and Tyr were determined by measurement of their derivatives by GC-MS in the selected ion monitoring mode. Contents of Phe and Tyr in blood spots were calculated by external standard method. The ratio of Phe to Tyr was used for neonatal screening for phenylketonuria. The present method only took a few minutes to perform and required minimal sample preparation. In addition it provided low detection limits of 1.2 micromol l(-1) for Phe and 1.6 micromol l(-1)for Tyr. PMID:12401368

  8. Use of Gas Chromatography-Mass Spectrometry (GC-MS) in Nonscience Major Course Laboratory Experiments

    NASA Astrophysics Data System (ADS)

    Kostecka, Keith S.; Lerman, Zafra M.; Angelos, Sanford A.

    1996-06-01

    Gas chromatography-mass spectrometry (GC-MS) has been utilized with nonscience majors in the courses: "Modern Methods in Science: Discovering Molecular Secrets"; "The Extraordinary Chemistry of Ordinary Things"; "From Ozone to Oil Spills: Chemistry, the Environment and You"; and "Crime Lab Chemistry: Solving Crime through Analytical Chemistry". Our efforts have centered on introducing prospective science communicators (film, video, radio, television, and journalism majors) to science relative to their majors and personal interests. Quality lecture-discussion topics, "mystery"-based laboratory activities have assisted in introducing and/or explaining specific areas of chemistry that attempt to reduce fear of subject matter. Students have also used GC-MS, as a form of alternative assessment, in course projects that have been based on their majors, personal interests, and cultural backgrounds. Students have also conducted advanced independent work in different areas of chemistry, including the analysis of nail polishes and lacquers and eleven aromatic compounds present in three different brands of gasoline.

  9. [Determination of primary aromatic amines in crayons gas chromatography-mass spectrometry].

    PubMed

    Kang, Suyuan; Zhang, Qing; Bai, Hua; Wang, Chao; Lü, Qing

    2011-05-01

    A method for the determination of nine primary aromatic amines in crayon by solid phase extraction (SPE) and gas chromatography-mass spectrometry (GC-MS) was developed. The alkanes in the sample were removed with n-hexane. Then the sample was extracted twice with ultrasonic extraction by methanol. The extract was evaporated, then the concentrated solution reacted with the reducing agent (sodium hydrosulfite) for 30 min at 70 degrees C. After the extraction with a diatomite SPE column, the aromatic amines were collected and separated on an HP-5M column, determined by MS. The nine primary aromatic amines can be separated and determined successfully. Under the optimized conditions, the detection limits were 5 mg/kg and the spiked recoveries of the samples were in the range of 86.02%-102.43%. The method is accurate and stable. It can be applied in the analysis of the primary aromatic amine of real crayon samples. PMID:21847976

  10. Gas Chromatography-Mass Spectrometry-Based Metabolic Profiling of Cerebrospinal Fluid from Epileptic Dogs

    PubMed Central

    HASEGAWA, Tetsuya; SUMITA, Maho; HORITANI, Yusuke; TAMAI, Reo; TANAKA, Katsuhiro; KOMORI, Masayuki; TAKENAKA, Shigeo

    2013-01-01

    ABSTRACT Epilepsy is a common neurological disorder with seizures, but diagnostic approaches in veterinary clinics remain limited. Cerebrospinal fluid (CSF) is a body fluid used for diagnosis in veterinary medicine. In this study, we explored canine epilepsy diagnostic biomarkers using gas chromatography-mass spectrometry (GC-MS)-based metabolic profiling of CSF and multivariate data analysis. Profiles for subjects with idiopathic epilepsy differed significantly from those of healthy controls and subjects with symptomatic epilepsy. Among 60 identified metabolites, the levels of 20 differed significantly among the three groups. Glutamic acid was significantly increased in idiopathic epilepsy, and some metabolites including ascorbic acid were changed in both forms of epilepsy. These findings show that metabolic profiles of CSF differ between idiopathic and symptomatic epilepsy and that metabolites including glutamic acid and ascorbic acid in CSF may be useful for diagnosis of canine epilepsy. PMID:24334864

  11. Determination of volatility distributions of primary organic aerosol emissions from internal combustion engines using thermal desorption gas chromatography mass spectrometry

    Microsoft Academic Search

    Albert A. Presto; Christopher J. Hennigan; Ngoc T. Nguyen; Allen L. Robinson

    2012-01-01

    A new technique for measuring the primary organic aerosol emissions from internal combustion engines is presented. The method combines thermal-optical OC\\/EC analysis and thermal desorption gas chromatography mass spectrometry (TD-GC-MS) of quartz filter samples collected using a dilution sampler to quantify the total emissions of low-volatility organics and to distribute them across the volatility basis set. These data can be

  12. Headspace single drop microextraction of methylcyclopentadienyl-manganese tricarbonyl from water samples followed by gas chromatography–mass spectrometry

    Microsoft Academic Search

    Francisco Javier Pena Pereira; Carlos Bendicho; Nicolas Kalogerakis; Elefteria Psillakis

    2007-01-01

    Headspace single drop microextraction coupled to gas chromatography–mass spectrometry yielded a simple, fast and virtually solventless analytical protocol used for the headspace analysis of aqueous samples contaminated with methylcyclopentadienyl-manganese tricarbonyl (MMT). Initially, several experimental parameters were controlled and optimized and the optimum conditions found were 2.5?l octane microdrop exposed for 20min to the headspace of a 10ml aqueous sample (15ml

  13. Molecular criteria for discriminating museum Asian lacquerware from different vegetal origins by pyrolysis gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    Anne-Solenn Le Hô; Martine Regert; Olivier Marescot; Chloé Duhamel; Juliette Langlois; Tetsuo Miyakoshi; Christophe Genty; Michel Sablier

    This paper focuses on the identification of several chemical markers of vegetal species of Oriental lacquers with the aim at providing a methodology consistent with sampling restrictions necessarily applied in the field of cultural heritage. The method proposed is based on rapid and easy single step thermally assisted hydrolysis–methylation (THM) pyrolysis-gas chromatography\\/mass spectrometry (Py-GC\\/MS) analysis that can be carried out

  14. Solidphase microextraction and gas chromatography–mass spectrometry for the rapid screening of triazole residues in wine and strawberries

    Microsoft Academic Search

    C. G Zambonin; A Cilenti; F Palmisano

    2002-01-01

    A solid-phase microextraction gas chromatography–mass spectrometry method has been developed for the determination of triazole residues, such as triadimefon, propiconazole, myclobutanil and penconazole. The method has been successfully applied to the analysis of strawberries and wine samples. The procedure is solvent-free, simple and highly sensitive. Within-day and day-to-day RSDs ranged between 2–11% and 7–28%, respectively. Detection limits estimated at a

  15. APPLICATION OF A SPRAY DEPOSITION METHOD FOR REVERSED PHASE LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY

    EPA Science Inventory

    Four coal gasification wastewater samples were analyzed for nonvolatile and polar organics by liquid chromatography-mass spectrometry (LC/MS). Samples were separated on a reverse phase liquid chromatographic column using an aqueous solvent as the eluant. A special spray depositio...

  16. Carbohydrate profiling of bacteria by gas chromatography-mass spectrometry: Chemical derivatization and analytical pyrolysis

    Microsoft Academic Search

    J. Gilbart; A. Fox; S. L. Morgan

    1987-01-01

    Carbohydrate profiling by gas chromatography-mass spectrometry is a powerful tool for the identification and detection of bacteria. Its increasing applicability in the microbiology laboratory is illustrated by three examples. In the first, differentiation of legionellae by their sugar composition was determined with alditol acetate derivatization followed by selectedion monitoring. In the second example, a carbohydrate pyrolysis product fromStreptococcus agalactiaewas used

  17. Identification of binding media in works of art by gas chromatography–mass spectrometry

    Microsoft Academic Search

    Carine Marinach; Marie-Christine Papillon; Claude Pepe

    2004-01-01

    This work presents a compilation of analytical procedures based on gas chromatography–mass spectrometry identification, which allow the determination of most of the binding media used in works of art, such as oils, wax, paraffin wax, lac resin, terpenic resins, glues and polysaccharides. The study of commercial products was done to determine markers for each binding media.

  18. Differentiating organically and conventionally grown oregano using ultraperformance liquid chromatography mass spectrometry (UPLC-MS), headspace gas chromatography with flame ionization detection (headspace-GC-FID), and flow injection mass spectrum (FIMS) fingerprints combined with multivariate data analysis.

    PubMed

    Gao, Boyan; Qin, Fang; Ding, Tingting; Chen, Yineng; Lu, Weiying; Yu, Liangli Lucy

    2014-08-13

    Ultraperformance liquid chromatography mass spectrometry (UPLC-MS), flow injection mass spectrometry (FIMS), and headspace gas chromatography (headspace-GC) combined with multivariate data analysis techniques were examined and compared in differentiating organically grown oregano from that grown conventionally. It is the first time that headspace-GC fingerprinting technology is reported in differentiating organically and conventionally grown spice samples. The results also indicated that UPLC-MS, FIMS, and headspace-GC-FID fingerprints with OPLS-DA were able to effectively distinguish oreganos under different growing conditions, whereas with PCA, only FIMS fingerprint could differentiate the organically and conventionally grown oregano samples. UPLC fingerprinting provided detailed information about the chemical composition of oregano with a longer analysis time, whereas FIMS finished a sample analysis within 1 min. On the other hand, headspace GC-FID fingerprinting required no sample pretreatment, suggesting its potential as a high-throughput method in distinguishing organically and conventionally grown oregano samples. In addition, chemical components in oregano were identified by their molecular weight using QTOF-MS and headspace-GC-MS. PMID:25050447

  19. Qualitative and Quantitative Characterization of Plasma Proteins When Incorporating Traveling Wave Ion Mobility into a Liquid Chromatography–Mass Spectrometry Workflow for Biomarker Discovery: Use of Product Ion Quantitation As an Alternative Data Analysis Tool for Label Free Quantitation

    PubMed Central

    2014-01-01

    Discovery of protein biomarkers in clinical samples necessitates significant prefractionation prior to liquid chromatography–mass spectrometry (LC–MS) analysis. Integrating traveling wave ion mobility spectrometry (TWIMS) enables in-line gas phase separation which when coupled with nanoflow liquid chromatography and data independent acquisition tandem mass spectrometry, confers significant advantages to the discovery of protein biomarkers by improving separation and inherent sensitivity. Incorporation of TWIMS leads to a packet of concentrated ions which ultimately provides a significant improvement in sensitivity. As a consequence of ion packeting, when present at high concentrations, accurate quantitation of proteins can be affected due to detector saturation effects. Human plasma was analyzed in triplicate using liquid-chromatography data independent acquisition mass spectrometry (LC-DIA-MS) and using liquid-chromatography ion-mobility data independent acquisition mass spectrometry (LC-IM-DIA-MS). The inclusion of TWIMS was assessed for the effect on sample throughput, data integrity, confidence of protein and peptide identification, and dynamic range. The number of identified proteins is significantly increased by an average of 84% while both the precursor and product mass accuracies are maintained between the modalities. Sample dynamic range is also maintained while quantitation is achieved for all but the most abundant proteins by incorporating a novel data interpretation method that allows accurate quantitation to occur. This additional separation is all achieved within a workflow with no discernible deleterious effect on throughput. Consequently, TWIMS greatly enhances proteome coverage and can be reliably used for quantification when using an alternative product ion quantification strategy. Using TWIMS in biomarker discovery in human plasma is thus recommended. PMID:24397486

  20. Qualitative and quantitative characterization of plasma proteins when incorporating traveling wave ion mobility into a liquid chromatography-mass spectrometry workflow for biomarker discovery: use of product ion quantitation as an alternative data analysis tool for label free quantitation.

    PubMed

    Daly, Charlotte E; Ng, Leong L; Hakimi, Amirmansoor; Willingale, Richard; Jones, Donald J L

    2014-02-18

    Discovery of protein biomarkers in clinical samples necessitates significant prefractionation prior to liquid chromatography-mass spectrometry (LC-MS) analysis. Integrating traveling wave ion mobility spectrometry (TWIMS) enables in-line gas phase separation which when coupled with nanoflow liquid chromatography and data independent acquisition tandem mass spectrometry, confers significant advantages to the discovery of protein biomarkers by improving separation and inherent sensitivity. Incorporation of TWIMS leads to a packet of concentrated ions which ultimately provides a significant improvement in sensitivity. As a consequence of ion packeting, when present at high concentrations, accurate quantitation of proteins can be affected due to detector saturation effects. Human plasma was analyzed in triplicate using liquid-chromatography data independent acquisition mass spectrometry (LC-DIA-MS) and using liquid-chromatography ion-mobility data independent acquisition mass spectrometry (LC-IM-DIA-MS). The inclusion of TWIMS was assessed for the effect on sample throughput, data integrity, confidence of protein and peptide identification, and dynamic range. The number of identified proteins is significantly increased by an average of 84% while both the precursor and product mass accuracies are maintained between the modalities. Sample dynamic range is also maintained while quantitation is achieved for all but the most abundant proteins by incorporating a novel data interpretation method that allows accurate quantitation to occur. This additional separation is all achieved within a workflow with no discernible deleterious effect on throughput. Consequently, TWIMS greatly enhances proteome coverage and can be reliably used for quantification when using an alternative product ion quantification strategy. Using TWIMS in biomarker discovery in human plasma is thus recommended. PMID:24397486

  1. 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…

  2. MATRIX EFFECTS IN LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY

    Microsoft Academic Search

    Achille Cappiello; Giorgio Famiglini; Pierangela Palma; Helga Trufelli

    2010-01-01

    Despite their enormous utility and diffusion, atmospheric pressure ionization mass spectrometry techniques are subjected to relevant drawbacks called matrix effects (ME). These effects could be summarized in matrix-dependent signal suppression or enhancement that could lead to erroneous quantitative results. The most important method parameters as well as linearity, precision, and accuracy could be modified due to interfering compounds present in

  3. Vanguard\\/rearguard strategy for the evaluation of the degradation of yoghurt samples based on the direct analysis of the volatiles profile through headspace-gas chromatography–mass spectrometry

    Microsoft Academic Search

    C. Carrillo-Carrión; S. Cárdenas; M. Valcárcel

    2007-01-01

    A vanguard\\/rearguard analytical strategy for the monitoring of the degradation of yoghurt samples is proposed. The method is based on the headspace-gas chromatography–mass spectrometry (HS-GC–MS) instrumental coupling. In this combination, the chromatographic column is firstly used as an interface between the HS and the MS (vanguard mode) avoiding separation of the volatile components by maintaining the chromatographic oven at high,

  4. Recent progress in polar metabolite quantification in plants using liquid chromatography–mass spectrometry.

    PubMed

    Liu, Zhiqian; Rochfort, Simone

    2014-09-01

    Metabolite analysis or metabolomics is an important component of systems biology in the post-genomic era. Although separate liquid chromatography (LC) methods for quantification of the major classes of polar metabolites of plants have been available for decades, a single method that enables simultaneous determination of hundreds of polar metabolites is possible only with gas chromatography–mass spectrometry (GC–MS) techniques. The rapid expansion of new LC stationary phases in the market and the ready access of mass spectrometry in many laboratories provides an excellent opportunity for developing LC–MS based methods for multi-target quantification of polar metabolites. Although various LC–MS methods have been developed over the last 10 years with the aim to quantify one or more classes of polar compounds in different matrices, currently there is no consensus LC–MS method that is widely used in plant metabolomics studies. The most promising methods applicable to plant metabolite analysis will be reviewed in this paper and the major problems encountered highlighted. The aim of this review is to provide plant scientists, with limited to moderate experience in analytical chemistry, with up-to-date and simplified information regarding the current status of polar metabolite analysis using LC–MS techniques. PMID:25340205

  5. Isotope dilution gas chromatography/mass spectrometry method for the determination of methionine sulfoxide in protein.

    PubMed

    Sochaski, M A; Jenkins, A J; Lyons, T J; Thorpe, S R; Baynes, J W

    2001-10-01

    We have developed a new technique for quantifying methionine sulfoxide (MetSO) in protein to assess levels of oxidative stress in physiological systems. In this procedure, samples are hydrolyzed with methanesulfonic acid (MSA) in order to avoid the conversion of MetSO to methionine (Met) that occurs during hydrolysis of protein in HCl. The hydrolysate is fractionated on a cation exchange column to remove the nonvolatile MSA from amino acids, and the amino acids are then derivatized as their trimethylsilyl esters for analysis by selected ion monitoring-gas chromatography/mass spectrometry. The limit of detection of the assay is 200 pmol of MetSO per analysis, and the interassay coefficient of variation is 5.8%. Compared to current methods, the SIM-GC/MS assay avoids the potential for conversion of Met to MetSO during sample preparation, requires less sample preparation time, has lower variability, and uses mass spectrometry for sensitive and specific analyte detection. PMID:11605844

  6. Large volume injection of water in gas chromatography–mass spectrometry using the Through Oven Transfer Adsorption Desorption interface: Application to multiresidue analysis of pesticides.

    PubMed

    Toledano, Rosa M; Cortés, Jose M; Andini, Juan C; Villén, Jesús; Vázquez, Ana

    2010-07-01

    In the present work, the potential of the Through Oven Transfer Adsorption Desorption (TOTAD) interface for the large volume injection (LVI) of aqueous samples in gas chromatography (GC) using a mass spectrometry (MS) detector is demonstrated. To this end, a new method for the determination of pesticides in water is presented, being the first developed method in which injection of large amounts of polar solvents using the TOTAD interface and an MS detector are combined, is applied to the determination of pesticides in water. Water samples, as large as 5 ml, were directly injected into a capillary GC. No sample pre-treatment step other than simple filtration was needed. The TOTAD interface allows the introduction of several millilitres of water, while maintaining good chromatographic characteristics. The water is almost entirely eliminated, so that LVI of aqueous samples and an MS detector can be used without problems. Organophosphorus, organochlorine, and triazine pesticides were determined in one run. Calibration curves were linear in the range tested and the sensitivity achieved injecting 5 ml of water sample was sufficient for most of the target pesticides but not for all of them. Sensitivity of the analysis can be improved by increasing the sample volume. No variability was observed in the retention times and relative standard deviations from absolute peak areas were good, considering that they corresponded to the overall analysis. The method was applied to the analysis of pesticide residues in real water samples. PMID:20605155

  7. Study of the microbiodegradation of terpenoid resin-based varnishes from easel painting using pyrolysis-gas chromatography-mass spectrometry and gas chromatography-mass spectrometry.

    PubMed

    Doménech-Carbó, María Teresa; Osete-Cortina, Laura; de la Cruz Cañizares, Juana; Bolívar-Galiano, Fernando; Romero-Noguera, Julio; Fernández-Vivas, María Antonia; Martín-Sánchez, Inés

    2006-08-01

    The alterations produced by microbiological attack on terpenoid resin-based varnishes from panel and canvas paintings have been evaluated using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and gas chromatography-mass spectrometry (GC-MS). The proposed methods include the on-line derivatisation of drying oils and diterpenoid resins using hexamethyldisilazane during pyrolysis and the application of methyl chloroformate as a derivatisation reagent for triterpenoid resins in GC-MS. Two types of specimens, consisting of model oil medium prepared from linseed oil and model spirit varnishes prepared from colophony and mastic resins dissolved in turpentine, have been used as reference materials. For a series of specimens upon which different genera of bacteria and fungi were inoculated and encouraged to grow, analyses indicated that no mechanisms that commonly occur during the attack of enzymes on drying oils and terpenoid biodegraders were observed to occur in the oil medium and varnishes studied. Thus, the degradation pathways observed in the performed trials usually occur as consequence of natural ageing. Specific trials consisting of the application of biocides to uninoculated colophony varnish resulted in the identification of processes that produce undesirable degradation of the varnish due to interactions between the biocide and the varnish components. Finally, the studied biocides--Biotin, New-Des and Nipagine--generally exhibited good inhibiting effects on the microorganisms studied, although some interesting differences were found between them regarding the application method and type of biocide. PMID:16826370

  8. Methods of analysis by the U.S. Geological Survey Organic Geochemistry Research Group : determination of triazine and phenylurea herbicides and their degradation products in water using solid-phase extraction and liquid chromatography/mass spectrometry

    USGS Publications Warehouse

    Lee, Edward Alan; Strahan, Alex P.; Thurman, Earl Michael

    2002-01-01

    An analytical method for the determination of 7 triazine and phenylurea herbicides and 12 of their degradation products in natural water samples using solid-phase extraction and liquid chromatography/mass spectrometry is presented in this report. Special consideration was given during the development of the method to prevent the formation of degradation products during the analysis. Filtered water samples were analyzed using 0.5 gram graphitized carbon as the solid-phase extraction media followed by liquid chromatography/mass spectrometry. Three different water-sample matrices?ground-water, surface-water, and reagent-water samples?spiked at 0.2 and 2.0 micrograms per liter were analyzed. Method detection limits ranged from 0.013 to 0.168 microgram per liter for the parent triazine herbicides and the triazine degradation products. Method detection limits ranged from 0.042 to 0.141 microgram per liter for the parent phenylurea herbicides and their degradation products. Mean recoveries for the triazine compounds in the ground- and surface-water samples generally ranged from 72.6 to 117.5 percent, but deethyl-cyanazine amide was recovered at 140.5 percent. Mean recoveries from the ground- and surface-water samples for the phenylurea compounds spiked at the 2.0-micrograms-per-liter level ranged from 82.1 to 114.4 percent. The mean recoveries for the phenylureas spiked at 0.2-microgram per liter were less consistent, ranging from 87.0 to 136.0 percent. Mean recoveries from reagent-water samples ranged from 87.0 to 109.5 percent for all compounds. The triazine compounds and their degradation products are reported in concentrations ranging from 0.05 to 2.0 micrograms per liter, with the exception of deethylcyanazine and deethylcyanazine amide which are reported at 0.20 to 2.0 micrograms per liter. The phenylurea compounds and their degradation products are reported in concentrations ranging from 0.20 to 2.0 micrograms per liter. The upper concentration limit was 2.0 micrograms per liter for all compounds without dilution.

  9. In Vitro Antibacterial Activity, Gas Chromatography–Mass Spectrometry Analysis of Woodfordia fruticosa Kurz. Leaf Extract and Host Toxicity Testing With In Vitro Cultured Lymphocytes From Human Umbilical Cord Blood

    PubMed Central

    Dubey, Debasmita; Patnaik, Rajashree; Ghosh, Goutam; Padhy, Rabindra N.

    2014-01-01

    Objectives To locate a plant with suitable phytochemicals for use as antimicrobial agents to control multidrug-resistant (MDR) bacteria as a complementary medicine, without host toxicity as monitored through cultured lymphocytes from human umbilical cord blood. Methods The methanol crude leaf extract of the plant Woodfordia fruticosa was subjected to antimicrobial assay in vitro with nine pathogenic MDR bacteria from clinical samples. This was followed by bioassay-guided fractionation with seven non-polar to polar solvents, gas chromatography–mass spectrometry analysis of the n-butanol fraction, and monitoring of the host toxicity of the leaf extract with in vitro grown lymphocytes from human umbilical cord blood. Results The leaf extract of W. fruticosa had a controlling capacity for MDR bacteria. The minimum inhibitory concentration and minimum bactericidal concentration of the n-butanol fraction were < 1.89 mg/mL extract and 9.63 mg/mL extract, respectively. The gas chromatography–mass spectrometry spectrum of the n-butanol fraction confirmed the presence of 13 peaks of different compounds with retention times of 9.11 minutes, 9.72 minutes, 10.13 minutes, 10.78 minutes, 12.37 minutes, 12.93 minutes, 18.16 minutes, 21.74 minutes, 21.84 minutes, 5.96 minutes, 12.93 minutes, 24.70 minutes, and 25.76 minutes. The six leading compounds were: diethyl phthalate: IUPAC name: diethyl benzene-1,2-dicarboxylate; 5-methyl-2-(1-methylethyl) phenol: IUPAC name: 5-methyl-2-propan-2-ylphenol; (E )-3,7-dimethylocta-2,6-diene-1-thiol: IUPAC name: (2Z)-3,7-dimethylocta-2,6-diene-1-thiol; 2,6,10-dodecatrien-1-ol, 3,7,11-trimethyl-, (E,E ): IUPAC name: 2,6,10-dodecatrien-1-ol; 3,7,11-trimethyl-, (E,E); 2-methoxy-4-(2-propenyl) phenol: IUPAC name: 2-methoxy-4-[(1E)-prop-1-en-1-yl]phenol; hexadecanoic acid: IUPAC name: hexadecanoic acid. Conclusion The presence of antimicrobial compounds that are therapeutically potent against MDR bacteria was confirmed in W. fruticosa. The crude leaf extract showed no host toxicity with human lymphocytes; the n-butanol fraction of the extract was the most suitable bioactive fraction. The terpenes isolated were: 5-methyl-2-(1-methylethyl) phenol, 2-methoxy-4-(2-propenyl) phenol, 2,6-octadien-1-ol, 3,7-dimethyl-(E)-2,6-octadienal, 3,7-dimethylcyclohexanol, and cyclohexanol, 2-methylene-5-(1-methylethenyl) which were reported to have specifically antimicrobial activity. PMID:25389517

  10. A liquid chromatography-mass spectrometry approach to study "glucosinoloma" in broccoli sprouts.

    PubMed

    Maldini, Mariateresa; Baima, Simona; Morelli, Giorgio; Scaccini, Cristina; Natella, Fausta

    2012-09-01

    Glucosinolates are an important class of secondary plant metabolites, possessing health-promoting properties. Young broccoli plants are a very good source of glucosinolates with concentrations several times greater than in mature plants. The aim of our study was to develop a liquid chromatography-mass spectrometry and liquid chromatography/tandem mass spectrometry qualitative and quantitative method for the measure of glucosinolates in broccoli sprouts. The described method provides high sensitivity and specificity, allowing a rapid and simultaneous determination of 14 glucosinolates. The proposed method has been validated for eight glucosinolates: glucobrassicin, glucoraphanin, glucoiberin, glucoerucin, progoitrin, gluconapin, sinigrin and glucocheirolin. The linear range was 1-150 µg ml(-1), the intra-day and inter-day precision values are within 6% and 8% at the lower limit of quantification, while the overall recovery of the eight glucosinolates was 99?±?9%. This validated method was used successfully for analysis of glucosinolates content of broccoli sprouts grown in different conditions. PMID:22972788

  11. Silicone rod extraction followed by liquid desorption-large volume injection-programmable temperature vaporiser-gas chromatography-mass spectrometry for trace analysis of priority organic pollutants in environmental water samples.

    PubMed

    Delgado, Alejandra; Posada-Ureta, Oscar; Olivares, Maitane; Vallejo, Asier; Etxebarria, Nestor

    2013-12-15

    In this study a priority organic pollutants usually found in environmental water samples were considered to accomplish two extraction and analysis approaches. Among those compounds organochlorine compounds, pesticides, phthalates, phenols and residues of pharmaceutical and personal care products were included. The extraction and analysis steps were based on silicone rod extraction (SR) followed by liquid desorption in combination with large volume injection-programmable temperature vaporiser (LVI-PTV) and gas chromatography-mass spectrometry (GC-MS). Variables affecting the analytical response as a function of the programmable temperature vaporiser (PTV) parameters were firstly optimised following an experimental design approach. The SR extraction and desorption conditions were assessed afterwards, including matrix modification, time extraction, and stripping solvent composition. Subsequently, the possibility of performing membrane enclosed sorptive coating extraction (MESCO) as a modified extraction approach was also evaluated. The optimised method showed low method detection limits (3-35 ng L(-1)), acceptable accuracy (78-114%) and precision values (<13%) for most of the studied analytes regardless of the aqueous matrix. Finally, the developed approach was successfully applied to the determination of target analytes in aqueous environmental matrices including estuarine and wastewater samples. PMID:24209370

  12. An automated method for the analysis of phenolic acids in plasma based on ion-pairing micro-extraction coupled on-line to gas chromatography/mass spectrometry with in-liner derivatisation.

    PubMed

    Peters, Sonja; Kaal, Erwin; Horsting, Iwan; Janssen, Hans-Gerd

    2012-02-24

    A new method is presented for the analysis of phenolic acids in plasma based on ion-pairing 'Micro-extraction in packed sorbent' (MEPS) coupled on-line to in-liner derivatisation-gas chromatography-mass spectrometry (GC-MS). The ion-pairing reagent served a dual purpose. It was used both to improve extraction yields of the more polar analytes and as the methyl donor in the automated in-liner derivatisation method. In this way, a fully automated procedure for the extraction, derivatisation and injection of a wide range of phenolic acids in plasma samples has been obtained. An extensive optimisation of the extraction and derivatisation procedure has been performed. The entire method showed excellent repeatabilities of under 10% and linearities of 0.99 or better for all phenolic acids. The limits of detection of the optimised method for the majority of phenolic acids were 10ng/mL or lower with three phenolic acids having less-favourable detection limits of around 100 ng/mL. Finally, the newly developed method has been applied in a human intervention trial in which the bioavailability of polyphenols from wine and tea was studied. Forty plasma samples could be analysed within 24h in a fully automated method including sample extraction, derivatisation and gas chromatographic analysis. PMID:22099223

  13. Automated headspace solid-phase microextraction versus headspace for the analysis of furan in foods by gas chromatography-mass spectrometry.

    PubMed

    Altaki, M S; Santos, F J; Galceran, M T

    2009-06-15

    A simple, fast and fully automated method based on headspace solid-phase microextraction coupled on-line with gas chromatography-ion trap mass spectrometry (HS-SPME-GC-ITMS) is proposed for furan determination in foods. The performance of the proposed method was compared to the automated headspace-GC-MS method, proposed by the US Food and Drugs Administration (US FDA), in terms of repeatability, limits of the detection and quantification. Both methods gave similar results for furan determination in selected food samples, although slightly worse precision (RSD%, 9-12%) and higher limits of detection (from 5 to 20 times higher) were obtained by the headspace method. In addition, higher sample throughput in routine furan analysis was obtained using the proposed HS-SPME-GC-ITMS method with isotope dilution than using the US FDA method, which recommends standard addition for quantification. The proposed method provides good precision (RSD% <10%) and low limits of detection, ranging from 0.02 to 0.12 ng g(-1) depending on the sample. The developed HS-SPME-GC-MS method was used to analyse furan in several Spanish food commodities and concentrations ranging from 0.1 ng g(-1) to 1.1 microg g(-1) were found. PMID:19362194

  14. Identification of Major Histocompatibility Complex-Regulated Body Odorants by Statistical Analysis of a Comparative Gas Chromatography/Mass Spectrometry Experiment

    SciTech Connect

    Willse, Alan R.; Belcher, Ann; Preti, George; Wahl, Jon H.; Thresher, Miranda; Yang, Peter; Yamazaki, Kunio; Beauchamp, Gary

    2005-04-15

    Gas chromatography (GC), combined with mass spectrometry (MS) detection, is a powerful analytical technique that can be used to separate, quantify, and identify volatile compounds in complex mixtures. This paper examines the application of GC-MS in a comparative experiment to identify volatiles that differ in concentration between two groups. A complex mixture might comprise several hundred or even thousands of volatile compounds. Because their number and location in a chromatogram generally are unknown, and because components overlap in populous chromatograms, the statistical problems offer significant challenges beyond traditional two-group screening procedures. We describe a statistical procedure to compare two-dimensional GC-MS profiles between groups, which entails (1) signal processing: baseline correction and peak detection in single ion chromatograms; (2) aligning chromatograms in time; (3) normalizing differences in overall signal intensities; and (4) detecting chromatographic regions that differ between groups. Compared to existing approaches, the proposed method is robust to errors made at earlier stages of analysis, such as missed peaks or slightly misaligned chromatograms. To illustrate the method, we identify differences in GC-MS chromatograms of ether-extracted urine collected from two nearly identical inbred groups of mice, to investigate the relationship between odor and genetics of the major histocompatibility complex.

  15. Determination of grinding aids in portland cement by pyrolysis gas chromatography-mass spectrometry

    Microsoft Academic Search

    A. A Jeknavorian; E. F Barry; F Serafin

    1998-01-01

    The pyrolysis of Portland cement followed by gas chromatography\\/mass spectrometry is described for the determination of chemical additives interground with cement clinkers known as grinding aids. This technique, coupled with in situ derivitization using BSTFA-TMCS reagent, has been found to be readily applicable for detecting phenol, along with five glycol and alkanolamine-type compounds in cement. The recovery rate was found

  16. Pesticide residue determination in fruit and vegetables by liquid chromatography–mass spectrometry

    Microsoft Academic Search

    Y Picó; J. C Moltó; J Mañes

    2000-01-01

    An overview is given of pesticide residue determination in fruit and vegetables by liquid chromatography–mass spectrometry (LC–MS). Emphasis is placed on the thermospray, particle beam and atmospheric pressure ionization interfaces including advantages and drawbacks and typical detection limits. The capacity of each interface to provide useful data for identification\\/confirmation of analytes and the possibility of obtaining structural information for the

  17. Quantification of clotiazepam in human plasma by gas chromatography–mass spectrometry

    Microsoft Academic Search

    Sung-Hoon Ahn; Han-Joo Maeng; Tae-Sung Koo; Dae-Duk Kim; Chang-Koo Shim; Suk-Jae Chung

    2006-01-01

    An analytical procedure was developed and validated for the quantification of clotiazepam in human plasma. After subjecting plasma samples to solid-phase extraction, the extract was evaporated and the residue re-constituted. An aliquot of the mixture was injected onto a gas chromatography–mass spectrometry system. The detector response was linear for clotiazepam concentrations in the range of 5–200ng\\/ml. Intra- and inter-day precision

  18. Determination of bisphenol A (BPA) in water by gas chromatography-mass spectrometry

    Microsoft Academic Search

    M. del Olmo; A. González-Casado; N. A. Navas; J. L. Vilchez

    1997-01-01

    A simple method for determination of bisphenol A in waters was developed using Gas Chromatography-Mass Spectrometry with a Selected Ion Monitoring (GC\\/MS-SIM). A 1000 ml water sample was extracted with dichloromethane in acid medium. No clean-up was necessary. Anthracene-d10 was used as an internal standard. The applicable concentration range was 2.5 to 10 ng ml?1 in water samples. The detection

  19. Pyrolysis–gas chromatography\\/mass spectrometry applied to the identification of different states of polyaniline

    Microsoft Academic Search

    L. Lizarraga; T. Verdejo; F. V. Molina; F. J. González-Vila

    2007-01-01

    Pyrolysis–gas chromatography\\/mass spectrometry (Py–CG\\/MS) has been applied to study and compare the composition of two electrochemically synthesized polyaniline (PANI) forms: fully reduced leucoemeraldine (LE) and intermediately oxidized emeraldine (EM). The different PANI forms were electrochemically synthesized using cyclic voltammetry. They were dedoped by stirring for 24h in ammoniacal solutions. Leucoemeraldine and emeraldine pyrograms presented differences in the relative intensity of

  20. Quantification of naltrexone and 6,?-naltrexol in plasma and milk using gas chromatography–mass spectrometry

    Microsoft Academic Search

    Chooi Fen Chan; Gregory M. Chiswell; Roberta Bencini; L. Peter Hackett; Leon J. Dusci; Kenneth F. Ilett

    2001-01-01

    A selective gas chromatography–mass spectrometry method using solid-phase extraction has been developed for the detection and quantification of naltrexone and its metabolite, 6,?-naltrexol in plasma and milk from humans and sheep at pharmacologically relevant concentrations. Di- or tri-acetyl derivatives were formed and quantified by selected-ion monitoring. Recoveries of naltrexone (30 ?g\\/l) and 6,?-naltrexol (250 ?g\\/l) from both human plasma and

  1. Picogram determination of estrogens in water using large volume injection gas chromatography–mass spectrometry

    Microsoft Academic Search

    Ruikang Hu; Lifeng Zhang; Zhaoguang Yang

    2008-01-01

    In this study, a simple and efficient large volume injection gas chromatography–mass spectrometry (GC-MS) method, via a programmable-temperature\\u000a vaporizer (PTV) inlet, has been developed and applied in the determination of estrogens in environmental water samples without\\u000a a prior derivatization process. Three commonly used estrogens estrone, 17 ?-estradiol and 17 ?-ethynylestradiol were selected\\u000a as target compounds for this study. It has been demonstrated

  2. Assay of serum allantoin in humans by gas chromatography–mass spectrometry

    Microsoft Academic Search

    Darrell V Pavitt; Sue de Fonseka; Nisrin Al-Khalaf; Janice M Cam; David A Reaveley

    2002-01-01

    Background: The small amount of allantoin present in human serum results from free radical (FR) action on urate and may provide a stable marker of free radical activity in vivo. We describe a gas chromatography–mass spectrometry (GC–MS) assay for serum allantoin and report a reference range in healthy individuals. Methods: Fasting blood samples were obtained from 134 healthy middle-aged volunteers

  3. Quantification of veterinary antibiotics (sulfonamides and trimethoprim) in animal manure by liquid chromatography–mass spectrometry

    Microsoft Academic Search

    Michel Y. Haller; Stephan R. Muller; Christa S. McArdell; Alfredo C. Alder; Marc J.-F. Suter

    2002-01-01

    A fast and cost effective method was developed to extract and quantify residues of veterinary antimicrobial agents (antibiotics) in animal manure by liquid–liquid extraction and liquid chromatography–mass spectrometry. The compounds investigated include six sulfonamides, one metabolite, and trimethoprim. The method was performed without sample clean up. Recoveries from spiked manure slurry samples (spike level=1 mg\\/kg) were as follows: sulfaguanidine (52%),

  4. Comparative quantification and identification of phosphoproteins using stable isotope labeling and liquid chromatography\\/mass spectrometry

    Microsoft Academic Search

    Wolfram Weckwerth; Lothar Willmitzer; Oliver Fiehn

    2000-01-01

    A new liquid chromatography\\/mass spectrometry (LC\\/MS) method is described for relative quantification of phosphoproteins to simultaneously compare the phosphorylation status of proteins under two different conditions. Quantification was achieved by b-elimination of phosphate from phospho-Ser\\/Thr followed by Micheal addition of ethanethiol and\\/or ethane-d5-thiol selectively at the vinyl moiety of dehydroalanine and dehydroamino-2-butyric acid. The method was evaluated using the model

  5. Metabolomic investigation of gastric cancer tissue using gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    Hao Wu; Ruyi Xue; Zhaoqing Tang; Chunhui Deng; Taotao Liu; Huazong Zeng; Yihong Sun; Xizhong Shen

    2010-01-01

    Gastric cancer screening or diagnosis is mainly based on endoscopy and biopsy. The aim of this study was to identify the difference\\u000a of metabolomic profile between normal and malignant gastric tissue, and to further explore tumor biomarkers. Chemical derivatization\\u000a together with gas chromatography\\/mass spectrometry (GC\\/MS) was utilized to obtain the metabolomic information of the malignant\\u000a and non-malignant tissues of gastric

  6. Gas chromatography-mass spectrometry assay for determination of ketamine in brain

    Microsoft Academic Search

    Yuri A Blednov; Victoria J Simpson

    1999-01-01

    A sensitive and precise gas chromatography–mass spectrometry method with selected ion monitoring has been developed for determination of ketamine in the brain using chlorpheniramine as an internal standard. The assay is based on the acid extraction of brain homogenate with hexane and ethyl ether with subsequent alkaline ethyl ether extraction. The analytical procedure has a coefficient of variation of 3.0–5.3%

  7. Determination of schizandrin in human plasma by gas chromatography-mass spectrometry

    Microsoft Academic Search

    Hiromasa Ono; Yutaka Matsuzaki; Yoko Wakui; Shuichi Takeda; Yukinobu Ikeya; Sakae Amagaya; Masao Maruno

    1995-01-01

    Schizandrin (SZ) is one of the lignan components from Schisandra fruits. A highly sensitive and precise method for the determination of SZ in human plasma was developed involving selected-ion monitoring with gas chromatography-mass spectrometry using a fused-silica capillary column. A 0.1-ml plasma sample was used for solid-phase extraction. A good linear relationship was obtained in the concentration range studied (2.0–500

  8. Determination of glyphosate, glyphosate metabolites, and glufosinate in human serum by gas chromatography–mass spectrometry

    Microsoft Academic Search

    Megumi Motojyuku; Takeshi Saito; Kazuki Akieda; Hiroyuki Otsuka; Isotoshi Yamamoto; Sadaki Inokuchi

    2008-01-01

    This paper describes an assay for the determination of glyphosate (GLYP), glyphosate metabolites [(aminomethyl) phosphonic acid] (AMPA), and glufosinate (GLUF) in human serum. After protein precipitation using acetonitrile and solid-phase extraction, serum samples were derivatized and analyzed by gas chromatography–mass spectrometry (GC–MS). The assay was linear over a concentration range of 3–100.0?g\\/ml for GLYP, AMPA, and GLUF. The overall recoveries

  9. Determination of Five Phthalate Monoesters in Human Urine Using Gas Chromatography-Mass Spectrometry

    Microsoft Academic Search

    Fumio Kondo; Yoshitomo Ikai; Rumiko Hayashi; Masanao Okumura; Satoshi Takatori; Hiroyuki Nakazawa; Shun-ichiro Izumi; Tsunehisa Makino

    2010-01-01

    We have developed a gas chromatography-mass spectrometry (GC–MS) method to determine five phthalate monoesters (monoethyl\\u000a phthalate (MEP), mono-n-butyl phthalate (MBP), mono-(2-ethylhexyl) phthalate (MEHP), monoisononyl phthalate (MINP) and monobenzyl phthalate (MBz))\\u000a in human urine. Human urine samples were subjected to enzymatic deconjugation of the glucuronides followed by extraction with\\u000a hexane. The extracted phthalate monoesters were methylated with diazomethane, purified on a

  10. Classification of High Speed Gas Chromatography-Mass Spectrometry Data by Principal Component Analysis Coupled with Piecewise Alignment and Feature Selection

    SciTech Connect

    Watson, Nathaniel E.; VanWingerden, Matthew M.; Pierce, Karisa M.; Wright, Bob W.; Synovec, Robert E.

    2006-09-01

    A useful procedure is introduced for the analysis of data obtained via gas chromatography with mass spectrometry (GC-MS) utilizing a complete mass spectrum at each retention time interval in which a mass spectrum was collected. Principal component analysis (PCA) with preprocessing by both piecewise retention time alignment and analysis of variance (ANOVA) feature selection is applied to all mass channels collected. The procedure involves concatenating all concurrently measured individual m/z chromatograms from m/z 20 to 120 for each GC-MS separation into a row vector. All of the sample row vectors are incorporated into a matrix where each row is a sample vector. This matrix is piecewise aligned and reduced by ANOVA feature selection. Application of the preprocessing steps (retention time alignment and feature selection) to all mass channels collected during the chromatographic separation allows considerably more selective chemical information to be incorporated in the PCA classification, and is the primary novelty of the report. This procedure is objective and requires no knowledge of the specific analytes of interest, as in selective ion monitoring (SIM), and does not restrict the mass spectral data used, as in both SIM and total ion current (TIC) methods. Significantly, the procedure allows for the classification of data with low resolution in the chromatographic dimension because of the added selectivity from the complete mass spectral dimension. This allows for the successful classification of data over significantly decreased chromatographic separation times, since high-speed separations can be employed. The procedure is demonstrated through the analysis of a set of four differing gasoline samples that serve as model complex samples. For comparison, the gasoline samples are analyzed by GC-MS over both ten-minute and ten-second separation times. The ten-minute GC-MS TIC data served as the benchmark analysis to compare to the ten-second data. When only alignment and feature selection was applied to the ten-second gasoline separations using GC-MS TIC data, PCA failed. PCA was successful for ten-second gasoline separations when the procedure was applied with all the m/z information. With ANOVA feature selection, chromatographic regions with Fisher Ratios greater than 1500 were retained in a new matrix and subjected to PCA yielding successful classification for the ten-second separations.

  11. Determination of N-nitrosodiethanolamine in cosmetic products by headspace solid phase microextraction using a novel aluminum hydroxide grafted fused silica fiber followed by gas chromatography-mass spectrometry analysis.

    PubMed

    Davarani, Saied Saeed Hosseiny; Masoomi, Leila; Banitaba, Mohammad Hossein; Zhad, Hamid Reza Lotfi Zadeh; Sadeghi, Omid; Samiei, Azam

    2013-02-15

    A method based on headspace solid phase microextraction with a new fiber, coupled with gas chromatography-mass spectrometry was developed for the determination of NDELA in cosmetic samples. The fiber provides Lewis acid-base interaction between its surface and analyte functional groups. The fiber was prepared by grafting aluminum tri-tert-butoxide on the surface of a fused silica. The optimization of SPME conditions showed that NDELA can be most effectively extracted at 70°C, in 15 min, with a sample volume of 0.5 (Vs/Vt), stirring rate of 150 rpm, desorption time of 5 min, desorption temperature of 260°C and at 12.5% (w/w) concentration of NaCl. Under the optimized conditions, LOD of 1 ?g Kg(-1) and a calibration curve with correlation coefficients greater than 0.9897 and a linearity range from 6 to 10000 ?g Kg(-1) were obtained. The intra-day and inter-day precision and accuracy were evaluated at four concentration levels. All of the values for accuracy and precision were lower than the acceptable limit of 15%. The fiber to fiber repeatability was 8.7%. The method was applied for the analysis of real samples including hair shampoo, body shampoo, dishwashing liquid and hand washing liquid. Relative recoveries were achieved in the range of 95-99%. PMID:23598029

  12. Methods of analysis by the U.S. Geological Survey Organic Geochemistry Research Group; 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

    Zimmerman, L.R.; 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: acetochlor ethanesulfonic acid (ESA), acetochlor oxanilic acid (OXA), alachlor ESA, alachlor OXA, metolachlor ESA, and metolachlor OXA. Good precision and accuracy were demonstrated for both the HPLC-DAD and HPLC/MS methods in reagent water, surface water, and ground water. The mean HPLC-DAD recoveries of the chloroacetanilide herbicide metabolites from water samples spiked at 0.25, 0.50, and 2.0 mg/L (micrograms per liter) ranged from 84 to 112 percent, with relative standard deviations of 18 percent or less. The mean HPLC/MS recoveries of the metabolites from water samples spiked at 0.05, 0.20, and 2.0 mg/L ranged from 81 to 125 percent, with relative standard deviations of 20 percent or less. The limit of quantitation (LOQ) for all metabolites using the HPLC-DAD method was 0.20 mg/L, whereas the LOQ using the HPLC/MS method was 0.05 mg/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.

  13. Data preprocessing method for liquid chromatography-mass spectrometry based metabolomics.

    PubMed

    Wei, Xiaoli; Shi, Xue; Kim, Seongho; Zhang, Li; Patrick, Jeffrey S; Binkley, Joe; McClain, Craig; Zhang, Xiang

    2012-09-18

    A set of data preprocessing algorithms for peak detection and peak list alignment are reported for analysis of liquid chromatography-mass spectrometry (LC-MS)-based metabolomics data. For spectrum deconvolution, peak picking is achieved at the selected ion chromatogram (XIC) level. To estimate and remove the noise in XICs, each XIC is first segmented into several peak groups based on the continuity of scan number, and the noise level is estimated by all the XIC signals, except the regions potentially with presence of metabolite ion peaks. After removing noise, the peaks of molecular ions are detected using both the first and the second derivatives, followed by an efficient exponentially modified Gaussian-based peak deconvolution method for peak fitting. A two-stage alignment algorithm is also developed, where the retention times of all peaks are first transferred into the z-score domain and the peaks are aligned based on the measure of their mixture scores after retention time correction using a partial linear regression. Analysis of a set of spike-in LC-MS data from three groups of samples containing 16 metabolite standards mixed with metabolite extract from mouse livers demonstrates that the developed data preprocessing method performs better than two of the existing popular data analysis packages, MZmine2.6 and XCMS(2), for peak picking, peak list alignment, and quantification. PMID:22931487

  14. Identification of Major Histocompatibility Complex-Regulated Body Odorants by Statistical Analysis of a Comparative Gas Chromatography\\/Mass Spectrometry Experiment

    Microsoft Academic Search

    Alan R. Willse; Anne M. Belcher; George Preti; Jon H. Wahl; Miranda Thresher; Peter Yang; Kunio Yamazaki; Gary K. Beauchamp

    2005-01-01

    Gas chromatography (GC), combined with mass spectrometry (MS) detection, is a powerful analytical technique that can be used to separate, quantify, and identify volatile compounds in complex mixtures. This paper examines the application of GC-MS in a comparative experiment to identify volatiles that differ in concentration between two groups. A complex mixture might comprise several hundred or even thousands of

  15. Factors That Contribute to Assay Variation in Quantitative Analysis of Sex Steroid Hormones Using Liquid and Gas Chromatography-Mass Spectrometry

    ERIC Educational Resources Information Center

    Xu, Xia; Veenstra, Timothy D.

    2012-01-01

    The list of physiological events in which sex steroids play a role continues to increase. To decipher the roles that sex steroids play in any condition requires high quality cohorts of samples and assays that provide highly accurate quantitative measures. Liquid and gas chromatography coupled with mass spectrometry (LC-MS and GC-MS) have…

  16. Identification and differentiation of methcathinone analogs by gas chromatography-mass spectrometry.

    PubMed

    Tsujikawa, Kenji; Mikuma, Toshiyasu; Kuwayama, Kenji; Miyaguchi, Hajime; Kanamori, Tatsuyuki; Iwata, Yuko T; Inoue, Hiroyuki

    2013-08-01

    To overcome a number of challenges involved in analyzing methcathinone (MC) analogues, we performed gas chromatography-mass spectrometry (GC-MS) analysis, including sample preparation, of nine MC analogues?-?4-methylmethcathinone, three positional isomers of fluoromethcathinones, 4-methoxymethcathinone, N-ethylcathinone, N,N-dimethylcathinone, buphedrone, and pentedrone. The MC analogues underwent dehydrogenation when the free bases were analyzed using splitless injection. Most of this thermal degradation was prevented using split injection. This indicated that a shorter residence time in the hot injector prevented decomposition. Uniquely, 2-fluoromethcathinone degraded to another product in a process that could not be prevented by the split injection. Replacing the liner with a new, clean one was also effective in preventing thermal degradation. Most of the analytes showed a substantial loss (>30%) when the free base solution in ethyl acetate was evaporated under a nitrogen stream. Adding a small amount of dimethylformamide as a solvent keeper had a noticeable effect, but it did not completely prevent the loss. Three positional isomers of fluoromethcathinones were separated with baseline resolution by heptafluorobutyrylation with a slow column heating rate (8?°C/min) using a non-polar DB-5?ms capillary column. These results will be useful for the forensic analysis of MC analogues in confiscated materials. PMID:23161815

  17. Optimization of solid phase microextraction coatings for liquid chromatography mass spectrometry determination of neurotransmitters.

    PubMed

    Cudjoe, Erasmus; Pawliszyn, Janusz

    2014-05-01

    A simple solid phase microextraction method coupled to liquid chromatography mass spectrometry is introduced for the analysis of neurotransmitter compounds with a wide range of polarities in biological matrices. A novel "reversed" reverse-phase chromatographic method was developed without pre-column derivatization for the analysis of dopamine, serotonin, gamma aminobutyric acid and glutamate. New solid phase microextraction "in house" coatings using mixed-mode solid phase extraction particles were prepared, and used for the extraction of polar neurotransmitters. The polymer-support base reverse phase mixed-mode sorbents with strong ion exchange properties generally had higher extraction efficiencies compared to similar sorbents with weak ion exchange properties. The linear range was determined to be between 0.01 and 150ng/mL for all the analytes, except for GABA, which was from 0.1 to 100ng/mL. The limit of detection range was from 6 to 10pg/mL for all the neurotransmitters, and the limits of quantitation were in the range of 20-35pg/mL. The results demonstrate the potential of the SPME-LC-MS/MS technique for bioanalysis of small polar endogenous compounds, such as neurotransmitters, from various biological matrices using the mixed-mode sorbents as the extraction phase. PMID:24685167

  18. Valid internal standard technique for arson detection based on gas chromatography-mass spectrometry.

    PubMed

    Salgueiro, Pedro A S; Borges, Carlos M F; Bettencourt da Silva, Ricardo J N

    2012-09-28

    The most popular procedures for the detection of residues of accelerants in fire debris are the ones published by the American Society for Testing and Materials (ASTM E1412-07 and E1618-10). The most critical stages of these tests are the conservation of fire debris from the sampling to the laboratory, the extraction of residues of accelerants from the debris to the activated charcoal strips (ACS) and from those to the final solvent, as well as the analysis of sample extract by gas chromatography-mass spectrometry (GC-MS) and the interpretation of the instrumental signal. This work proposes a strategy for checking the quality of the sample conservation, the accelerant residues transference to final solvent and GC-MS analysis, using internal standard additions. It is used internal standards ranging from a highly volatile compound for checking debris conservation to low volatile compound for checking GC-MS repeatability. The developed quality control (QC) parameters are not affected by GC-MS sensitivity variation and, specifically, the GC-MS performance control is not affected by ACS adsorption saturation that may mask test performance deviations. The proposed QC procedure proved to be adequate to check GC-MS repeatability, ACS extraction and sample conservation since: (1) standard additions are affected by negligible uncertainty and (2) observed dispersion of QC parameters are fit for its intended use. PMID:22920302

  19. Automated high-speed analysis of selected organic compounds in urban air by on-line isotopic dilution cryofocusing gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    E. Davoli; L. Cappellini; M. Maggi; R. Fanelli

    1994-01-01

    An automated environmental air monitor has been developed to measure selected organic compounds in urban air. The instrument\\u000a is based on a cryofocusing-thermal desorption gas chromatographic mass spectrometry technique where the mass spectrometer\\u000a is a slightly modified residual gas analyzer (RGA). The RGA was chosen as a detector because the whole system must be robust\\u000a for long periods, with 24-h

  20. Thermal degradation of ?-pyrrolidinopentiophenone during injection in gas chromatography/mass spectrometry.

    PubMed

    Tsujikawa, Kenji; Kuwayama, Kenji; Kanamori, Tatsuyuki; Iwata, Yuko T; Inoue, Hiroyuki

    2013-09-10

    ?-Pyrrolidinopentiophenone (?-PVP) is a popular recreational drug in Japan. This drug easily undergoes thermal decomposition during gas chromatography/mass spectrometry analysis. We evaluated three factors involved in the decomposition, namely the injection method (splitless or split, split ratio), injector temperature, and surface activity on the inlet liner. Splitless injection of ?-PVP using a used deactivated split/splitless liner at an injector temperature of 250 °C caused thermal decomposition. This decomposition was inhibited by split injection. A higher split ratio resulted in greater prevention. Based on the mass spectrum of deuterated ?-PVP, the decomposition product was presumed to be an enamine whose double bond was located in the alkyl chain. Lowering the injection temperature from 250 °C to 200 °C did not prevent decomposition. New glass liners, both deactivated and non-deactivated, were compared. The use of a new deactivated liner minimized thermal decomposition, even for splitless injection, while the non-deactivated liner generated an increase in the amount of the decomposition product. These results showed that the injection method and the surface activity on the inlet liner were involved in the thermal decomposition of ?-PVP. PMID:23890652

  1. Automated thermochemolysis reactor for detection of Bacillus anthracis endospores by gas chromatography-mass spectrometry.

    PubMed

    Li, Dan; Rands, Anthony D; Losee, Scott C; Holt, Brian C; Williams, John R; Lammert, Stephen A; Robison, Richard A; Tolley, H Dennis; Lee, Milton L

    2013-05-01

    An automated sample preparation system was developed and tested for the rapid detection of Bacillus anthracis endospores by gas chromatography-mass spectrometry (GC-MS) for eventual use in the field. This reactor is capable of automatically processing suspected bio-threat agents to release and derivatize unique chemical biomarkers by thermochemolysis (TCM). The system automatically controls the movement of sample vials from one position to another, crimping of septum caps onto the vials, precise delivery of reagents, and TCM reaction times and temperatures. The specific operations of introduction of sample vials, solid phase microextraction (SPME) sampling, injection into the GC-MS system, and ejection of used vials from the system were performed manually in this study, although they can be integrated into the automated system. Manual SPME sampling is performed by following visual and audible signal prompts for inserting the fiber into and retracting it from the sampling port. A rotating carousel design allows for simultaneous sample collection, reaction, biomarker extraction and analysis of sequential samples. Dipicolinic acid methyl ester (DPAME), 3-methyl-2-butenoic acid methyl ester (a fragment of anthrose) and two methylated sugars were used to compare the performance of the autoreactor with manual TCM. Statistical algorithms were used to construct reliable bacterial endospore signatures, and 24 out of 25 (96%) endospore-forming Bacillus species were correctly identified in a statistically designed test. PMID:23601976

  2. [Simultaneous determination of nine preservatives in fruits using gas chromatography-mass spectrometry].

    PubMed

    Peng, Shunü; Wang, Qiuquan; Fang, Lanlan; Guo, Shanyong; Zeng, Zhouhua; Lin, Zhuguang

    2014-01-01

    A gas chromatography-mass spectrometry (GC-MS) method was established for the simultaneous determination of nine typical preservatives (pyrimethanil, chlorothalonil, chlorpyrifos, triadimefon, thiabendazole, imazalil, myclobutanil, iprodione, prochloraz) in fruits. The fruit samples were subjected to ultrasonic extraction with hexane/ethyl acetate (1/1, v/v), and followed by purification using diatomite column chromatography with hexane/ethyl acetate (1/3, v/v) eluant. Qualitative and quantitative analysis of the nine preservatives were performed on the GC-MS at full-scan (SCAN) and selected ion monitoring (SIM) modes, in which triphenylphosphate was used as the internal standard. The detection limits obtained for the nine preservatives were ranged from 0.10 microg/kg to 2.16 microg/kg. The average recoveries were in the range of 75.3% to 128% at the spiked levels of 50, 100 and 200 microg/kg with the relative standard deviations (RSDs) of 1.57% to 11.6% (n = 5). The results showed that the developed method is sensitive and accurate for the determination of the nine preservatives in fruits. PMID:24783871

  3. Profiling of Serum Metabolites in Canine Lymphoma Using Gas Chromatography Mass Spectrometry

    PubMed Central

    TAMAI, Reo; FURUYA, Masaru; HATOYA, Shingo; AKIYOSHI, Hideo; YAMAMOTO, Ryohei; KOMORI, Yoshiaki; YOKOI, Shin-ichi; TANI, Kenichiro; HIRANO, Yuji; KOMORI, Masayuki; TAKENAKA, Shigeo

    2014-01-01

    ABSTRACT Canine lymphoma is a common cancer that has high rates of complete remission with combination chemotherapy. However, the duration of remission varies based on multiple factors, and there is a need to develop a method for early detection of recurrence. In this study, we compared the metabolites profiles in serum from 21 dogs with lymphoma and 13 healthy dogs using gas chromatography mass spectrometry (GC-MS). The lymphoma group was separated from the control group in an orthogonal projection to latent structure with discriminant analysis (OPLS-DA) plot using ions of m/z 100–600, indicating that the metabolites profiles in lymphoma cases differed from those in healthy dogs. The lymphoma group was also separated from the control group on OPLS-DA plot using 29 metabolites identified in all serum samples. Significant differences were found for 16 of these metabolites with higher levels in the lymphoma group for 15 of the metabolites and lower levels for inositol. An OPLS-DA plot showed separation of the lymphoma and healthy groups using these 16 metabolites only. These results indicate that metabolites profile with GC-MS may be a useful tool for detection of potential biomarker and diagnosis of canine lymphoma. PMID:25131950

  4. Integration of gas chromatography mass spectrometry methods for differentiating ricin preparation methods.

    PubMed

    Wunschel, David S; Melville, Angela M; Ehrhardt, Christopher J; Colburn, Heather A; Victry, Kristin D; Antolick, Kathryn C; Wahl, Jon H; Wahl, Karen L

    2012-05-01

    The investigation of crimes involving chemical or biological agents is infrequent, but presents unique analytical challenges. The protein toxin ricin is encountered more frequently than other agents and is found in the seeds of Ricinus communis, commonly known as the castor plant. Typically, the toxin is extracted from castor seeds utilizing a variety of different recipes that result in varying purity of the toxin. Moreover, these various purification steps can also leave or differentially remove a variety of exogenous and endogenous residual components with the toxin that may indicate the type and number of purification steps involved. We have applied three gas chromatography-mass spectrometry (GC-MS) based analytical methods to measure the variation in seed carbohydrates and castor oil ricinoleic acid, as well as the presence of solvents used for purification. These methods were applied to the same samples prepared using four previously identified toxin preparation methods, starting from four varieties of castor seeds. The individual data sets for seed carbohydrate profiles, ricinoleic acid, or acetone amount each provided information capable of differentiating different types of toxin preparations across seed types. However, the integration of the data sets using multivariate factor analysis provided a clear distinction of all samples based on the preparation method, independent of the seed source. In particular, the abundance of mannose, arabinose, fucose, ricinoleic acid, and acetone were shown to be important differentiating factors. These complementary tools provide a more confident determination of the method of toxin preparation than would be possible using a single analytical method. PMID:22416271

  5. Identification and quantitation of trenbolone in bovine tissue by gas chromatography-mass spectrometry.

    PubMed

    Hsu, S H; Eckerlin, R H; Henion, J D

    1988-02-26

    Identification and quantitation of trace amounts of trenbolone in bovine tissue by capillary gas chromatography-mass spectrometry-selected-ion monitoring (GC-MS-SIM) has been developed. Three-phase liquid-liquid extraction using a mixture of water-acetonitrile-dichloromethane-hexane was utilized for the sample extraction from tissue. Target compounds were extracted from the tissue into the acetonitrile layer. The residue from this extraction was then subjected to solid-phase extraction by C18 and silica gel disposable cartridges using methanol-water and benzene-acetone as eluents. To overcome extensive matrix interferences, preparative reversed-phase high-performance liquid chromatographic separation was used with an octadecyl-bonded column using methanol-water as mobile phase for sample clean-up prior to GC-MS analysis. A structural analogue of trenbolone, 19-nortestosterone, was chosen as the internal standard for quantitation by GC-MS. The sample was co-injected with N,O-bis (trimethylsilyl) trifluoroacetamide-1-(trimethylsilyl) imidazole (95:5, v/v) for flash heater derivation. Identification and quantitation were simultaneously carried out by SIM of characteristic ions of the trimethylsilyl derivatives of trenbolone and 19-nortestosterone. The limit of detection for trenbolone and epitrenbolone was 0.5 ppb in muscle and liver tissue. A comparison of sensitivity and specificity between GC-MS under electron ionization in addition to positive- and negative-ion chemical ionization conditions using methane reagent gas is also discussed. PMID:3372619

  6. Specific estimation of 24,25-dihydroxyvitamin D in plasma by gas chromatography-mass spectrometry.

    PubMed

    Coldwell, R D; Trafford, D J; Makin, H L; Varley, M J; Kirk, D N

    1984-07-01

    This paper describes a specific mass-fragmentographic method, involving a stable-isotope-labeled internal standard, for measurement of 24,25-dihydroxyvitamin D in human plasma. Vitamin D metabolites were rapidly extracted from plasma by using Sep-Pak C18 cartridges and separated into fractions on Sep-Pak SIL cartridges. The polar fraction, containing the dihydroxylated metabolites, was further purified by "high-performance" liquid chromatography on Zorbax SIL. The fraction containing 24,25-dihydroxyvitamin D was collected, evaporated, and converted to the 24:25-cyclic n-butyl boronate-3-trimethylsilyl ether derivative before analysis by gas chromatography-mass spectrometry. The intensity of the mass fragment (m/z 449, m/z 455 for the hexadeuterated internal standard) arising from the loss of one of the angular methyls and the 3-silanol group [( M-90-15]+) was monitored. The minimum limit of detection for this method is about 0.1 microgram/L. Inter- and intra-assay reproducibility was acceptable, and analytical recovery of added 24,25-dihydroxyvitamin D3 over the concentration range 1.0 to 5.0 micrograms/L was quantitative. Concentrations of 24,25-dihydroxyvitamin D3 in plasma of 21 apparently healthy volunteers were between 0.55 and 5.39 micrograms/L, higher values being obtained after prolonged exposure to the sun. No 24,25-dihydroxyvitamin D2 could be detected in any plasma sample examined. PMID:6610503

  7. Study on essential oils from four species of Zhishi with gas chromatography–mass spectrometry

    PubMed Central

    2014-01-01

    Background Citrus fruits are widely used as food and or for medicinal purposes, and they contain a host of active substances that contribute to health. The immature fruits of Citrus sinensis Osbeck and its cultivars (CS), C. junos Sieb. ex Tanaka (CJ), C. aurantium L. and its cultivars (CA) and Poncirus trifoliate Raf. (PT) are the most commonly used medicinal herbs in Traditional Chinese Medicine, called Zhishi. And their mature fruits can be used as food. Results In this study, the essential oils of four different Zhishi species were extracted by steam distillation and detected using gas chromatography- mass spectrometry (GC-MS). A total of 39 volatiles from the four species were tentatively identified. The limonene was the most abundant amongst the four species. Principal component analysis (PCA) of essential oils showed a clear separation of volatiles among CS, CJ and PT. However, CA could not be separated from these three species. Additionally, the volatiles accounting for the variations among the widely separated species were characterized through their corresponding loading weight. Conclusion Sesquiterpenes were identified as characteristic markers for PT. The content of some monoterpenes could be as taxonomic markers between CS and CJ. This work is of great importance for the evaluation and authentication of Zhishi samples through essential oils. PMID:24708882

  8. Analysis of 1-hydroxypyrene in urine as PAH exposure marker using in-situ derivatisation stir bar sorptive extraction-thermal desorption-capillary gas chromatography-mass spectrometry

    Microsoft Academic Search

    K. Desmet; B. Tienpont; P. Sandra

    2003-01-01

    Summary  A fast and rabust method for the determination of 1-hydroxypyrene (OH-pyrene) and other hydroxylated PAHs in urine by stir\\u000a bar sorptive extraction (SBSE) combined with thermal desorption-capillarygas chromatography-mass spectrometry (TD-CGC-MS)\\u000a is described. After enzymatic hydrolysis, in-situ derivatisation with acelic acid anhydride precedes SBSE sampling to improve\\u000a the chromatographic behavior of the analytes. The performance of the method has been evalucted

  9. Analysis of potential migrants from plastic materials in milk by liquid chromatography-mass spectrometry with liquid-liquid extraction and low-temperature purification.

    PubMed

    Bodai, Zsolt; Szabó, Bálint Sámuel; Novák, Márton; Hámori, Susanne; Nyiri, Zoltán; Rikker, Tamás; Eke, Zsuzsanna

    2014-10-15

    A simple and fast analytical method was developed for the determination of six UV stabilizers (Cyasorb UV-1164, Tinuvin P, Tinuvin 234, Tinuvin 326, Tinuvin 327, and Tinuvin 1577) and five antioxidants (Irgafos 168, Irganox 1010, Irganox 3114, Irganox 3790, and Irganox 565) in milk. For sample preparation liquid-liquid extraction with low-temperature purification combined with centrifugation was used to remove fats, proteins, and sugars. After the cleanup step, the sample was analyzed with high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). External standard and matrix calibrations were tested. External calibration proved to be acceptable for Tinuvin P, Tinuvin 234, Tinuvin 326, Tinuvin 327, Irganox 3114, and Irganox 3790. The method was successfully validated with matrix calibration for all compounds. Method detection limits were between 0.25 and 10 ?g/kg. Accuracies ranged from 93 to 109%, and intraday precisions were <13%. PMID:25251884

  10. Analysis of protein composition of red wine in comparison with rose? and white wines by electrophoresis and high-pressure liquid chromatography-mass spectrometry (HPLC-MS).

    PubMed

    Wigand, Petra; Tenzer, Stefan; Schild, Hansjoerg; Decker, Heinz

    2009-05-27

    Wine proteins not only influence wine stability but are also being discussed as potential allergens. Proteins from red, rose?, and white wines were enriched by dialysis and lyophilization followed by separation by SDS-PAGE. Significant differences were detected in the protein compositions of the analyzed wine varieties, and the major protein bands were identified by mass spectrometry after in-gel digestion with trypsin. In German Portugieser red wine, a total of 121 tryptic peptides were identified, which were attributed to 12 grape proteins and 6 proteins derived from yeast. Among the identified constituents are several proteins considered to influence wine stability and previously described potential grape allergens. The pathogenesis-related proteins represent the main proteins in all of the wines, but only some red wines show a band with a molecular mass of 12 kDa, identified as a lipid transfer protein (LTP). The occurrence and distribution of LTP depend on the wine variety. PMID:19385597

  11. Liquid chromatography-mass spectrometry method for the analysis of 1,4-dimethylpyridinium in rat plasma--application to pharmacokinetic studies.

    PubMed

    Szafarz, Malgorzata; Szymura-Oleksiak, Joanna; Zakrzewska, Agnieszka; Walczak, Maria; Kus, Kamil; Gonciarz, Anna

    2013-01-01

    A sensitive and specific liquid chromatography electrospray ionization-mass spectrometry method for determination of 1,4-dimethylpyridinium (1,4-DMP) in rat plasma has been developed and validated. Chromatography was performed on an Aquasil C(18) analytical column (4.6?×?150?mm, 5?µm, Thermo Scientific, Rockford, IL, USA) with isocratic elution using a mobile phase containing acetonitrile and water with an addition of 0.1% of formic acid. Detection was achieved by an Applied Biosystems MDS Sciex (Concord, Ontario, Canada) API 2000 triple quadrupole mass spectrometer. Electrospray ionization was used for ion production. The limit of detection in the single ion monitoring mode was found to be 10?ng/mL. The limit of quantification was 50?ng/mL. The precision and accuracy for both within-day and between-day determination of 1,4-dimethylpyridinium was 2.4-7.56 and 90.93-111.48%. The results of this analytical method validation allow pharmacokinetic studies to be carried out in rats. The method was used for the pilot study of the pharmacokinetic behavior of 1,4-DMP in rats after intravenous administration. PMID:22549824

  12. Solid-phase microextraction on-fiber derivatization for the analysis of some polyphenols in wine and grapes using gas chromatography-mass spectrometry.

    PubMed

    Viñas, Pilar; Campillo, Natalia; Martínez-Castillo, Nelson; Hernández-Córdoba, Manuel

    2009-02-27

    The present study describes a new environmentally friendly sample pretreatment system based on solid-phase microextraction (SPME) for the sensitive determination of polyphenols. A derivatization process was necessary to convert the polar non-volatile compounds into volatile derivatives. Direct immersion (DI) SPME was used for the adsorption of polyphenols, and then the fiber was placed in the headspace of the derivatizing reagent, bis(trimethylsilyl)trifluoroacetamide (BSTFA). The separation was carried out by coupling gas chromatography with mass spectrometry in the selected ion monitoring mode, after silylation. Optimal extraction conditions were 25 degrees C for 10 min under continuous stirring using DI and a polyacrylate fiber. After extraction, the fiber was inserted into the headspace of BSTFA (10 microL) and the polyphenols were derivatized for 15 min at 50 degrees C. Desorption was carried out at 280 degrees C for 5 min. The method allowed the determination of both isomers cis- and trans-resveratrol, piceatannol, catechin and epicatechin in wine and grapes, and it was validated for linearity, detection and quantitation limits, selectivity, accuracy and precision. Detection limits ranged from 0.05 to 0.9 ng mL(-1) at a signal-to-noise ratio of 3, depending on the compound. Recoveries obtained for spiked samples were satisfactory for all compounds. PMID:19150539

  13. Improved methods for urinary atrazine mercapturate analysis--assessment of an enzyme-linked immunosorbent assay (ELISA) and a novel liquid chromatography-mass spectrometry (LC-MS) method utilizing online solid phase extraction (SPE).

    PubMed

    Koivunen, Marja E; Dettmer, Katja; Vermeulen, Roel; Bakke, Berit; Gee, Shirley J; Hammock, Bruce D

    2006-07-21

    Elimination of interfering substances in urine by solid phase extraction (SPE) prior to analysis resulted in 10-fold improvement in the sensitivity of atrazine mercapturate (AM) enzyme-linked immunosorbent assay (ELISA) compared to previous reports. Of the two tested SPE systems, Oasis HLB and MCX, the mixed-mode MCX gave good recoveries (82%) of AM in spiked samples measured by ELISA, whereas the reverse-phase HLB phase was not compatible with the immunochemical method. At relatively high concentrations of urinary AM (>20 ng mL(-1)), sample dilution was effective enough for the elimination of interfering substances. The new liquid chromatography-mass spectrometry (LC-MS) method developed for AM utilizes online-SPE with Oasis HLB, column switching and a stable-isotope internal standard. The limit of quantification (0.05 ng mL(-1)) indicates improved sensitivity compared with most previously published LC-MS methods for AM. Validation of all three methods, LC-MS, ELISA+SPE and ELISA+dilution with spiked urine samples showed good correlation between the known and measured concentrations with R2 values of 0.996, 0.957 and 0.961, respectively. When a set (n=70 plus 12 blind duplicates) of urine samples from farmers exposed to atrazine was analyzed, there was a good agreement (R2=0.917) between the log normalized data obtained by ELISA+SPE and LC-MS. High correlation among the data obtained by the two tested methods and the LC-MS method by the Center of Disease Control and Prevention (CDC), together with low variability among the blind duplicates, suggests that both methods reported here would be suitable for the analysis of urinary AM as a biomarker for human exposure of atrazine. PMID:17723476

  14. Characterization of human skin emanations by Solid Phase Microextraction (SPME) extraction of volatiles and subsequent analysis by Gas Chromatography-Mass Spectrometry (GC-MS)

    E-print Network

    Akin James (James J.)

    2005-01-01

    An experimental study was performed to develop and validate a collection and analysis protocol for human skin emanations. The protocol developed included the rubbing of glass beads on the palms and backs of hands for 20 ...

  15. Development of a method for the simultaneous analysis of anionic and non-ionic surfactants and their carboxylated metabolites in environmental samples by mixed-mode liquid chromatography-mass spectrometry.

    PubMed

    Lara-Martín, Pablo A; Gómez-Parra, Abelardo; González-Mazo, Eduardo

    2006-12-29

    A new methodology capable of performing the simultaneous analysis of the main surfactants--linear alkylbenzene sulfonates (LAS), alkyl ethoxysulfates (AES), alkyl sulfates (AS), nonylphenol polyethoxylates (NPEOs) and alcohol polyethoxylates (AEOs)--and their carboxylated metabolites--sulfophenyl carboxylic acids (SPCs) and alkylphenol ethoxycarboxylates (APECs)--in environmental samples has been developed for the first time. Extraction is carried out by solid-phase extraction (SPE) and pressurized liquid extraction (PLE) from water and sediment, respectively. Identification and quantification of the target compounds is performed using a liquid chromatography-mass spectrometry (LC-MS) system equipped with an electrospray interface (ESI) operating in mixed-mode. Optimization of parameters such as pH, ionic strength, temperature and solvents has been carried out in order to obtain recoveries in the range from 70 to 107% for most homologs, while the limits of detection are 0.05-0.5 ng mL(-1) in water and 1-10 ng g(-1) in sediment. The proposed methodology has been applied for the simultaneous determination of all the target compounds in samples taken from aquatic ecosystems in the SW of Spain. Values for LAS, AS, AES, NPEOs and AEOs are up to 38.7, 3.0, 2.9, 5.0 and 1.2 microg L(-1) in waters, and in the ranges of 1.73-12.80, 0.11-0.24, 0.02-0.59, 1.94-2.70 and 0.64-3.64 mg kg(-1) in sediments, respectively. The highest concentrations of metabolites found in water are 149.6 microg L(-1) of SPCs and 3.9 microg L(-1) of APECs. PMID:17070820

  16. Methods of analysis by the U.S. Geological Survey Organic Geochemistry Research Group : determination of selected herbicides and their degradation products in water using solid-phase extraction and gas chromatography/mass spectrometry

    USGS Publications Warehouse

    Kish, J.L.; Thurman, E.M.; Scribner, E.A.; Zimmerman, L.R.

    2000-01-01

    A method for the extraction and analysis of eight herbicides and five degradation products using solid-phase extraction from natural water samples followed by gas chromatography/mass spectrometry is presented in this report. This method was developed for dimethenamid; flufenacet; fluometuron and its degradation products, demethylfluometuron (DMFM), 3-(trifluromethyl)phenylurea (TFMPU), 3-(trifluromethyl)-aniline (TFMA); molinate; norflurazon and its degradation product, demethylnorflurazon; pendamethalin; the degradation product of prometryn, deisopropylprometryn; propanil; and trifluralin. The eight herbicides are used primarily in the southern United States where cotton, rice, and soybeans are produced. The exceptions are dimethenamid and flufenacet, which are used on corn in the Midwest. Water samples received by the U.S. Geological Survey's Organic Geochemistry Research Group in Lawrence, Kansas, are filtered to remove suspended particulate matter and then passed through disposable solid-phase extraction columns containing octadecyl-bonded porous silica (C-18) to extract the compounds. The herbicides and their degradation products are removed from the column by ethyl acetate elution. The eluate is evaporated under nitrogen, and components then are separated, identified, and quantified by injecting an aliquot of the concentrated extract into a high-resolution, fused-silica capillary column of a gas chromatograph/mass spectrometer under selected-ion mode. Method detection limits ranged from 0.02 to 0.05 ?g/L for all compounds with the exception of TFMPU, which has a method detection limit of 0.32 ?g/L. The mean absolute recovery is 107 percent. This method for the determination of herbicides and their degradation products is valuable for acquiring information about water quality and compound fate and transport in water.

  17. Methods of Analysis by the U.S. Geological Survey Organic Geochemistry Research Group-Update and Additions to the Determination of Chloroacetanilide Herbicide Degradation Compounds in Water Using High-Performance Liquid Chromatography/Mass Spectrometry

    USGS Publications Warehouse

    Lee, E.A.; Kish, J.L.; Zimmerman, L.R.; Thurman, E.

    2001-01-01

    An analytical method using high-performance liquid chromatography/mass spectrometry (HPLC/MS) was developed by the U.S. Geological Survey in 1999 for the analysis of selected chloroacetanilide herbicide degradation compounds in water. These compounds were acetochlor ethane sulfonic acid (ESA), acetochlor oxanilic acid (OXA), alachlor ESA, alachlor OXA, metolachlor ESA, and metolachlor OXA. The HPLC/MS method was updated in 2000, and the method detection limits were modified accordingly. Four other degradation compounds also were added to the list of compounds that can be analyzed using HPLC/MS; these compounds were dimethenamid ESA, dimethenamid OXA, flufenacet ESA, and flufenacet OXA. Except for flufenacet OXA, good precision and accuracy were demonstrated for the updated HPLC/MS method in buffered reagent water, surface water, and ground water. The mean HPLC/MS recoveries of the degradation compounds from water samples spiked at 0.20 and 1.0 ?g/L (microgram per liter) ranged from 75 to 114 percent, with relative standard deviations of 15.8 percent or less for all compounds except flufenacet OXA, which had relative standard deviations ranging from 11.3 to 48.9 percent. Method detection levels (MDL's) using the updated HPLC/MS method varied from 0.009 to 0.045 ?g/L, with the flufenacet OXA MDL at 0.072 ?g/L. The updated HPLC/MS method is valuable for acquiring information about the fate and transport of the parent chloroacetanilide herbicides in water.

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

    PubMed

    Guo, Liang; Lee, Hian Kee

    2014-04-15

    An innovative automated procedure, low-density solvent based/solvent demulsification dispersive liquid-liquid microextraction (automated DLLME) coupled to gas chromatography-mass spectrometry (GC/MS) analysis, has been developed. The most significant innovation of the method is the automation. The entire procedure, including the extraction of the model analytes (phthalate esters) by DLLME from the aqueous sample solution, breaking up of the emulsion after extraction, collection of the extract, and analysis of the extract by GC/MS, was completely automated. The applications of low-density solvent as extraction solvent and the solvent demulsification technique to break up the emulsion simplified the procedure and facilitated its automation. Orthogonal array design (OAD) as an efficient optimization strategy was employed to optimize the extraction parameters, with all the experiments conducted auotmatically. An OA16 (4(1) × 2(12)) matrix was initially employed for the identification of optimized extraction parameters (type and volume of extraction solvent, type and volume of dispersive solvent and demulsification solvent, demulsification time, and injection speed). Then, on the basis of the results, more levels (values) of five extraction parameters were investigated by an OA16 (4(5)) matrix and quantitatively assessed by the analysis of variance (ANOVA). Enrichment factors of between 178- and 272-fold were obtained for the phthalate esters. The linearities were in the range of 0.1 and 50 ?g/L and 0.2 and 50 ?g/L, depending on the analytes. Good limits of detection (in the range of 0.01 to 0.02 ?g/L) and satisfactory repeatability (relative standard deviations of below 5.9%) were obtained. The proposed method demonstrates for the first time integrated sample preparation by DLLME and analysis by GC/MS that can be operated automatically across multiple experiments. PMID:24666227

  19. Gas chromatography/mass spectrometry characterization of historical varnishes of ancient Italian lutes and violin.

    PubMed

    Echard, J P; Benoit, C; Peris-Vicente, J; Malecki, V; Gimeno-Adelantado, J V; Vaiedelich, S

    2007-02-12

    The organic constituents of historical vanishes from two ancient Italian lutes and a Stradivari violin, kept in the Musée de la musique in Paris, have been characterized using gas chromatography-mass spectrometry. Results have been compared with the chromatograms and mass spectra of recent as well as old naturally aged reference materials. The three historical varnishes analyzed have been shown to be oil varnishes, probably mixtures of linseed oil with resins. Identification of diterpenoids and triterpenoids compounds, and of the resins that may have been ingredients of the varnishes, are discussed in this paper. PMID:17386601

  20. Method to detect contaminants in heparin using radical depolymerization and liquid chromatography-mass spectrometry.

    PubMed

    Li, Guoyun; Cai, Chao; Li, Lingyun; Fu, Li; Chang, Yuqing; Zhang, Fuming; Toida, Toshihiko; Xue, Changhu; Linhardt, Robert J

    2014-01-01

    Heparin is a critically important anticoagulant drug that was contaminated with a persulfonated polysaccharide in 2008, resulting in a number of severe adverse reactions, some leading to death. Controversy remains as to the precise composition of the 2008 contaminant, and new information suggests that heparin may now be subject to adulteration with a new, difficult to detect, contaminant, N-sulfo oversulfated chondroitin sulfate. This study synthesizes this new potential contaminant and describes the use of radical depolymerization followed by liquid chromatography-mass spectrometry to detect N-sulfo oversulfated chondroitin sulfate and to confirm the structure of the 2008 contaminant as oversulfated chondroitin sulfate and not oversulfated heparan sulfate. PMID:24364596

  1. Headspace solid-phase microextraction gas chromatography-mass spectrometry and gas chromatography-olfactometry analysis of volatile compounds in pineapple breads.

    PubMed

    Ying, Saw; Lasekan, Ola; Naidu, Kalla Reddi Mohan; Lasekan, Seye

    2012-01-01

    Sensorial analysis of pineapple breads (conventionally baked, Cpb; fully baked frozen, Fpb and partially baked, Ppb) showed no significant differences in terms of aroma and taste. On the contrary, the scores for the overall quality between the partially baked and conventionally baked breads showed significant (p < 0.05) differences. At the same time, headspace analysis using a solid-phase microextraction (SPME) method identified 59 volatile compounds. The results of the aroma extracts dilution analysis (AEDA) revealed 19 most odour-active compounds with FD factors in the range of 32-128 as the key odourants of the pineapple breads. Further analysis of the similarities and differences between the pineapple breads in terms of the key odourants were carried out by the application of PLS-DA and PLS-regression coefficients. Results showed that Ppb exhibited strong positive correlations with most of the volatile- and non-volatile compounds, while the Cpb showed significant positive correlations with hexanal and 4-hydroxy-2,5-dimethyl-3(2H)-furanone, and the Fpb had strong positive correlations with lactic acid, benzoic acid, benzaldehyde and ethyl propanoate. PMID:23174897

  2. COMPARATIVE ANALYSIS OF POLYCHLORINATED DIBENZO-P-DIOXIN AND DIBENZOFURAN CONGENERS IN GREAT LAKES FISH EXTRACTS BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY AND IN VITRO ENZYME INDUCTION ACTIVITIES

    EPA Science Inventory

    The high-resolution gas chromatographic-mass spectrometric analysis of 25 Great Lakes fish extracts confirmed the identities of several 2,3,7,8-tetrasubstituted polychlorinated dibenzofurans (PCDFs) and dibenzo-p-dioxins (PCDDs). The dominant congener in extracts from Lake Michig...

  3. Foodomics platform for the assay of thiols in wines with fluorescence derivatization and ultra performance liquid chromatography mass spectrometry using multivariate statistical analysis.

    PubMed

    Inoue, Koichi; Nishimura, Maiko; Tsutsui, Haruhito; Min, Jun Zhe; Todoroki, Kenichiro; Kauffmann, Jean-Michel; Toyo'oka, Toshimasa

    2013-02-13

    The presence of specific volatile and aminothiols in wine is associated with quality, worth, price, and taste. The identification of specific thiol-containing compounds in various wines has been reported in many valuable and interesting works. In this study, a novel foodomics assay of thiol-containing compounds, such as free aminothiols and related conjugates, was developed using ultra performance liquid chromatography (UPLC) with fluorescence (FL) and electrospray (ESI) time-of-flight mass spectrometric (TOF/MS) detections. FL specific derivatization was applied along with multivariate statistical analysis. First, the optimal experimental conditions were studied using representative thiols, such as l-cysteine, N-acetyl-l-cysteine, cysteamine, and l-glutathione, and then the UPLC-FL derivatization and separation steps were fixed for the subsequent screening of unknown thiol-containing compounds. The screening assay consisted of monitoring the UPLC-TOF/MS peaks of unknown thiols, which decreased due to the derivatization as compared to the nonderivatized thiols. The principal component analysis of the UPLC-TOF/MS data could be well-differentiated and categorized into two groups. The orthogonal signal correction partial least-squares discriminant analysis, the so-called S-plot, showed that the quality differentiation is directly related to the decrease of native thiols and increase of derivatized thiols. With this strategy, the mass difference from the derivatization reagent (+m/z 198) could be utilized for the identification of these thiols using the FL peaks retention time and metabolomics-databases. The presence of l-glutathione in rice wine was for the first time reported on the basis of the available metabolomics-databases and standard matching. This novel concept based on foodomics could be applied in food analysis for the ready screening of specific functional compounds by exploiting the various derivatization modes available. PMID:23339461

  4. Comprehensive Analysis of a Multidimensional Liquid Chromatography Mass Spectrometry Dataset Acquired on a Quadrupole Selecting, Quadrupole Collision Cell, Time-of-flight

    Microsoft Academic Search

    Mass Spectrometer; Robert J. Chalkley; Peter R. Baker; Kirk C. Hansen; Katalin F. Medzihradszky; Nadia P. Allen; Michael Rexach; Alma L. Burlingame

    A thorough analysis of the protein interaction partners of the yeast GTPase Gsp1p was carried out by a multidimen- sional chromatography strategy of strong cation ex- change fractionation of peptides followed by reverse phase LC-ESI-MSMS using a QSTAR instrument. This dataset was then analyzed using the latest developmental version of Protein Prospector. The Prospector search re- sults were also compared

  5. Increasing productivity for the analysis of trace contaminants in food by gas chromatography-mass spectrometry using automated liner exchange, backflushing and heart-cutting.

    PubMed

    David, Frank; Tienpont, Bart; Devos, Christophe; Lerch, Oliver; Sandra, Pat

    2013-10-25

    Laboratories focusing on residue analysis in food are continuously seeking to increase sample throughput by minimizing sample preparation. Generic sample extraction methods such as QuEChERS lack selectivity and consequently extracts are not free from non-volatile material that contaminates the analytical system. Co-extracted matrix constituents interfere with target analytes, even if highly sensitive and selective GC-MS/MS is used. A number of GC approaches are described that can be used to increase laboratory productivity. These techniques include automated inlet liner exchange and column backflushing for preservation of the performance of the analytical system and heart-cutting two-dimensional GC for increasing sensitivity and selectivity. The application of these tools is illustrated by the analysis of pesticides in vegetables and fruits, PCBs in milk powder and coplanar PCBs in fish. It is demonstrated that considerable increase in productivity can be achieved by decreasing instrument down-time, while analytical performance is equal or better compared to conventional trace contaminant analysis. PMID:23891373

  6. Analysis of linear and cyclic methylsiloxanes in sewage sludges and urban soils by concurrent solvent recondensation-large volume injection-gas chromatography-mass spectrometry.

    PubMed

    Companioni-Damas, E Y; Santos, F J; Galceran, M T

    2012-12-14

    Concurrent solvent recondensation-large volume injection (CSR-LVI) is a gas chromatography injection technique that is particularly suitable for determining volatile compounds. In the present work, we evaluated the applicability of this technique for the analysis of linear and cyclic methylsiloxanes in sewage sludges and soils after solvent extraction to prevent losses of low-molecular-weight compounds. The CSR-LVI injection method was optimised to achieve maximum sensitivity and good chromatographic peak shapes. A liner packed with deactivated glass wool and a 5 m × 0.32 mm I.D. uncoated fused-silica precolumn was used. This made it possible to inject extract volumes of up to 30 ?l. Good linearity (r>0.9993) and precision (RSD <15%), with recoveries ranging from 80 to 100% and method limits of quantification from 0.03 to 0.4 ng g(-1) wet weight (0.04-1.5 ng g(-1) dry weight for sewage sludges and 0.01-0.5 ng g(-1) dry weight for soils) were obtained. The developed method was applied to the analysis of linear and cyclic methylsiloxanes in sewage sludges collected from several wastewater treatment plants in Catalonia (NE Spain) and urban soils from the city of Barcelona. PMID:23141621

  7. Trifluoroacetic anhydride-catalyzed nitration of toluene as an approach to the specific analysis of nitrate by gas chromatography-mass spectrometry.

    PubMed

    Smythe, G A; Matanovic, G; Yi, D; Duncan, M W

    1999-01-01

    The nitration of aromatic compounds by electrophilic substitution is often utilized in analyses of nitrate concentrations in physiological samples by gas chromatographic methods. Problems associated with the use of concentrated sulfuric acid, which is normally used to catalyze this reaction, led us to investigate an alternative method. We describe here a facile GC/MS assay for nitrate in plasma or urine samples which takes advantage of the ability of trifluoroacetic anhydride (TFAA) to catalyze the nitration of aromatics. Toluene, utilized as both reaction solvent and electrophile, was shown to react with nitrate in the presence of TFAA to quantitatively produce the three nitrotoluene isomers (ratio o-:m:p-, approx 57:3:40). Following the incorporation of 15N-labeled nitrate as internal standard, nitrotoluene was quantified using GC/MS by analysis of the selected the ion pairs m/z 120 and 121 (M+ -OH) for the o-isomer or m/z 137 and 138 (molecular ion, M+) for the p-isomer. The limit of detection for nitrate after TFAA-catalyzed conversion to nitrotoluene was less than 100 fmol on column (s/n; 40:1). The TFAA-based GC/MS assay was compared with that utilizing the usual catalyst, concentrated sulfuric acid. With the exception of samples containing nitroarginine analogues, good correlation was found for urine or plasma samples analyzed using either a standard sulfuric acid-catalyzed method or the TFAA-catalyzed procedure. Nitroarginine analogues, which can be present in samples following their use as nitric oxide synthase inhibitors, did not decompose under the conditions of the TFAA-catalyzed assay and, hence, do not give rise to significant interference with nitrate analysis in this procedure. In contrast, catalytic sulfuric acid caused nitroarginine analogues to decompose (essentially quantitatively) and cause spuriously high nitrate levels in samples. The use of TFAA as a catalyst for the nitration of toluene enables a facile and sensitive GC/MS analysis for nitrate which offers improved safety and sample integrity. PMID:10355897

  8. Qualitative and quantitative analysis of vetiver essential oils by comprehensive two-dimensional gas chromatography and comprehensive two-dimensional gas chromatography/mass spectrometry.

    PubMed

    Filippi, Jean-Jacques; Belhassen, Emilie; Baldovini, Nicolas; Brevard, Hugues; Meierhenrich, Uwe J

    2013-05-01

    Vetiver essential oils (VEO) are important raw ingredients used in perfume industry, entering the formula of numerous modern fragrances. Vetiver oils are considered to be among the most complex essential oils, resulting most of the time in highly coeluted chromatograms whatever the analytical technique. In this context, conventional gas chromatography has failed to provide a routine tool for the accurate qualitative and quantitative analysis of their constituents. Applying comprehensive two-dimensional gas chromatography techniques (GC×GC-FID/MS) afforded the mean to separate efficiently vetiver oil constituents in order to identify them in a more reliable way. Moreover, this is the first time that a complete true quantitation of each constituent is carried out on such complex oils by means of internal calibration. Finally, we have studied the influence of the injection mode on the determined chemical composition, and showed that several alcohols underwent dehydration under defined chromatographic conditions (splitless mode) usually recommended for quantitation purposes. PMID:23522261

  9. The role of the acquisition methods in the analysis of natural and synthetic steroids and cholic acids by gas chromatography-mass spectrometry.

    PubMed

    Andrási, N; Helenkár, A; Vasanits-Zsigrai, A; Záray, Gy; Molnár-Perl, I

    2011-11-11

    An exhaustive GC-MS acquisition study was performed, for the simultaneous analysis of natural and synthetic steroids and cholic acids (in order to insert them into the last tierce of our multiresidue analysis system), such as androsterone, ?-estradiol, transdehydroandro-sterone, transdehyroandrosterone, mestranol, dihydrotestosterone, ethinylestradiol, testosterone, norethisterone, estriol, 4-androstene-3,17-dione, gestodene, levonorgestrel, etonogestrel, coprostanol, progesterone, cholesterol, medroxyprogesterone-acetate, lithocholic acid, stigmasterol, cholic acid, chenodeoxycholic acid, ?-sitosterol, ursodeoxycholic acid, 3-hydroxy-7-ketocholic acid and dehydrocholic acid, in total 26 compounds. As novelties to the field, for the trimethylsilyl (TMS) oxime ether/ester derivatives of steroids and cholic acids, at first, a tandem mass spectrometric (MS/MS), multiple reaction monitoring (MRM) type acquisition method has been developed in a single run; also for the first time, the three acquisition techniques, the full scan (FS), the selective ion monitoring (SIM), in our case the multiple ion monitoring (MIM) and the currently optimized MRM methods, have been compared; all three, in parallel, under strictly the same derivatization/instrumental conditions, both in matrix free solutions and municipal wastewater from two Hungarian wastewater treatment plants (WWTPs). Critical evaluation of the three acquisition protocols was collated on their analytical performances and validated under the same conditions. The data of six point calibration curves for FS, MIM and MRM methods, showed that both R² (0.9995, 0.9858, 0.9975) and RSD (5.3, 5.8, 5.0), for two parallel derivatizations, each injected three times, proved to be independent of the acquisition processes. Whereas, for the method limit of quantification (LOQ) and the instrument limit of quantification (ILQ) values showed considerable differences. LOQ data, were decreasing in the FS, MIM, MRM line (expressed in ng/L), for all steroids and cholic acids. The same trend was determined in terms of the ILQ values. The practical utility of the optimized acquisition techniques was confirmed by the quantitation of the steroids and cholic acids contents of wastewater samples. Results confirmed the importance of the MRM acquisition method, even in comparison to the MIM one: with particular interest in selected cases: avoiding the extreme overestimation of the ?-estradiol (156-1325%) and that of the ethinylestradiol (582-831%) concentrations in the wastewater samples. PMID:21981935

  10. Universal Route to Polycyclic Aromatic Hydrocarbon Analysis in Foodstuff: Two-Dimensional Heart-Cut Liquid Chromatography-Gas Chromatography-Mass Spectrometry.

    PubMed

    Nestola, Marco; Friedrich, Rainer; Bluhme, Patrick; Schmidt, Torsten C

    2015-06-16

    Analysis of polycyclic aromatic hydrocarbons (PAHs) in complex foodstuff is associated with complicated and work-intensive sample preparation. Chromatographic interference has to be faced in many situations. The scope of the current work was the development of a highly efficient two-dimensional heart-cut LC-LC-GC-MS method. Detection was performed with a time-of-flight mass spectrometer (TOF-MS) to allow for a comprehensive evaluation of the obtained data in terms of cleanup efficiency. Additionally, routine detection was performed with single quadrupole MS. An easy and quick generic sample preparation protocol was realized as a first step. During method development, focus was given to optimizing HPLC cleanup for complex foodstuff. Silica-, polymeric-, and carbon-based HPLC phases were tested. Coupling of silica gel to ?-electron acceptor modified silica gel showed the best cleanup properties. A four rotary valve configuration allowed the usage of a single binary HPLC pump. Screening of several fatty and nonfatty food matrices showed the absence of unwanted matrix compounds in the cleaned-up PAH fraction down to the low picogram range using TOF-MS. Limits of quantitation (LOQ) were below 0.1 ?g/kg for all EU priority PAHs. Recovery rates ranged from 82 to 111%. Validation data fully complied with EU Regulation 836/2011. Sample preparation was possible in 20 min. Interlacing of HPLC and GC allowed an average method runtime of 40 min per sample. PMID:26011005

  11. Multiresidue method for the analysis of five antifouling agents in marine and coastal waters by gas chromatography-mass spectrometry with large-volume injection.

    PubMed

    Agüera, A; Piedra, L; Hernando, M D; Fernández-Alba, A R

    2000-08-11

    A simple multiresidue method has been developed for the determination of five pesticides, commonly used as active ingredients in antifouling paints, in seawater samples. The pesticides studied were: chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile), dichlofluanid (N-dimethyl-N-phenylsulphamide), Sea-Nine 211 (4,5-dichloro-2-n-octyl-4-isothazolin-3-one), Irgarol 1051 (2-methylthio-4-tert.-butylamino-6-cyclopropylamino-s-triazine) and TCMTB (2-thiocyanomethylthiobenzothiazole). The analytes were extracted from 200 ml water samples, using solid-phase extraction. A copolymer with hydrophilic-lipophilic balance was used as sorbent yielding good recoveries (82-95%) for most compounds except dichlofluanid and Sea-Nine 211 (<60%). Large volume injection (10 microl) gas chromatography and electron impact ionization MS (selected ion monitoring mode) detection enabled these compounds to be identified and quantified at the 1.2-3.0 ng/l level. Analysis of samples performed in three marinas in Almería (Spain) revealed the presence of Irgarol 1051 in all the cases, at concentration levels between 25 and 450 ng/l. PMID:10985557

  12. Analysis of free and protein-bound nitrotyrosine in human plasma by a gas chromatography/mass spectrometry method that avoids nitration artifacts.

    PubMed Central

    Frost, M T; Halliwell, B; Moore, K P

    2000-01-01

    Measurement of nitrotyrosine in biological fluids and tissues is increasingly being used to monitor the production of reactive nitrogen species in vivo. The detection of nitrotyrosine in vivo has been reported with the use of a variety of methods including immunoassay, HPLC and GLC/MS. The validity of HPLC and immunoassays have been questioned with regard to their selectivity and sensitivity limits. In principle, the measurement of nitrotyrosine by GLC/MS permits a highly specific, highly sensitive and fully quantitative assay. The nitration of tyrosine under acidic conditions in the presence of nitrite is well documented. Derivatization for the full quantification of nitrotyrosine by using GLC/MS can lead to the artifactual nitration of tyrosine if performed under acidic conditions in the presence of nitrite. We describe a novel alkaline method for the hydrolysis and derivatization of nitrotyrosine and tyrosine, and demonstrate its applicability to the measurement of plasma concentrations of both free and protein-bound nitrotyrosine and tyrosine. A detection limit of 1 pg for nitrotyrosine and 100 pg for tyrosine has been achieved. Our method allows, for the first time, the analysis of free and protein-bound nitrotyrosine and tyrosine in biological samples. The plasma concentrations (means+/-S.E.M.) of free tyrosine and nitrotyrosine in eight normal subjects were 12+/-0.6 microg/ml and 14+/-0.7 ng/ml respectively. Plasma proteins contained tyrosine and nitrotyrosine at 60.7+/-1.7 microg/mg and 2.7+/-0.4 ng/mg respectively. PMID:10642501

  13. Analysis of free and protein-bound nitrotyrosine in human plasma by a gas chromatography/mass spectrometry method that avoids nitration artifacts.

    PubMed

    Frost, M T; Halliwell, B; Moore, K P

    2000-02-01

    Measurement of nitrotyrosine in biological fluids and tissues is increasingly being used to monitor the production of reactive nitrogen species in vivo. The detection of nitrotyrosine in vivo has been reported with the use of a variety of methods including immunoassay, HPLC and GLC/MS. The validity of HPLC and immunoassays have been questioned with regard to their selectivity and sensitivity limits. In principle, the measurement of nitrotyrosine by GLC/MS permits a highly specific, highly sensitive and fully quantitative assay. The nitration of tyrosine under acidic conditions in the presence of nitrite is well documented. Derivatization for the full quantification of nitrotyrosine by using GLC/MS can lead to the artifactual nitration of tyrosine if performed under acidic conditions in the presence of nitrite. We describe a novel alkaline method for the hydrolysis and derivatization of nitrotyrosine and tyrosine, and demonstrate its applicability to the measurement of plasma concentrations of both free and protein-bound nitrotyrosine and tyrosine. A detection limit of 1 pg for nitrotyrosine and 100 pg for tyrosine has been achieved. Our method allows, for the first time, the analysis of free and protein-bound nitrotyrosine and tyrosine in biological samples. The plasma concentrations (means+/-S.E.M.) of free tyrosine and nitrotyrosine in eight normal subjects were 12+/-0.6 microg/ml and 14+/-0.7 ng/ml respectively. Plasma proteins contained tyrosine and nitrotyrosine at 60.7+/-1.7 microg/mg and 2.7+/-0.4 ng/mg respectively. PMID:10642501

  14. Application of QuEChERS method for extraction of selected persistent organic pollutants in fish tissue and analysis by gas chromatography mass spectrometry.

    PubMed

    Norli, Hans Ragnar; Christiansen, Agnethe; Deribe, Ermias

    2011-10-14

    The QuEChERS method developed for 22 organochlorine pesticides (OCPs) and 7-polychlorinated biphenyls (PCBs) in fish tissue involves a simple and efficient freezing technique for removal of lipids. The equipment developed consists of disposable syringes and a freezing block constructed from simple materials found in most laboratories. The freezing block keeps the temperature in the extract at -20.5°C up to 10 min after being exposed to room temperature. After the freezing step 69% of the lipids in tilapia and 61% in salmon are removed. Further reduction of co-extractives up to 96% in tilapia and 87% in salmon can be made by treatment with CaCl(2) and primary secondary amino sorbent (PSA) which removes the fatty acids. Spiking experiments in tilapia at 5 and 50 ng/g and extracted with acetonitrile show recovery range from 70 to 115% for all compounds. In salmon the recoveries are in the range 43-118% for the OCPs and 26-65% for the PCBs. Analysis of a standard reference material shows acceptable results for most of the pesticides but low results for the PCBs. The estimated LOQs were in the range 1-5 ng/g for tilapia and 2-10 ng/g for salmon. The method has been applied to analyse fish samples from Lake Koka in Ethiopia. It was investigated if addition of a less polar water miscible solvent than acetonitrile could increase the recovery of OCPs and PCBs. The results show that a mixture of 75% acetonitrile and 25% tetrahydrofurane (ACN/THF 75/25) clearly enhances the recoveries for most OCPs (47-101%) and PCBs (42-79%) from salmon. The recovery of aldrin increases significantly from 55% to over 80%. The method using ACN/THF 75/25 is applicable to the extraction of OCPs and PCBs from fish tissue having a lipid content of up to about 11% (salmon) with recoveries ?70% for most of the OCPs and ?42% for the PCBs. PMID:21899854

  15. Systematic derivatization, mass fragmentation and acquisition studies in the analysis of chlorophenols, as their silyl derivatives by gas chromatography-mass spectrometry.

    PubMed

    Faludi, T; Andrási, N; Vasanits-Zsigrai, A; Záray, Gy; Molnár-Perl, I

    2013-08-01

    An exhaustive GC-MS sample preparation, derivatization, mass fragmentation and acquisition study was performed, for the simultaneous analysis of chlorophenols (CPs). Selected species were 2-CP, 3-CP, 4-CP, 3,5-dichlorophenol (diCP), 2,5-diCP, 2,6-diCP, 2,4-diCP, 2,3-diCP, 3,4-diCP 2,4,6-trichlorophenol (triCP), 2,4,5-triCP, 2,3,4-triCP, 2,3,4,6-tetrachlorophenol (tetraCP) and pentachlorophenol (pentaCP), in total 14 compounds. As novelties to the field, basic researches, like systematic derivatization, mass fragmentation and acquisition methods have been optimized for the trimethylsilyl (TMS) ether derivatives of CPs. The reactivity of chlorophenols with silylating agents has not been systematically analyzed. Here, we studied the reactivity of 14 chlorophenols with five silylating reagents. The three acquisition techniques, the full scan (FS), the multiple ion monitoring (MIM), and the currently optimized multiple reaction monitoring (MRM) methods, have been compared. We developed a new analytical approach, simultaneously monitoring the fragmentation pattern of the (35)Cl and the (37)Cl containing fragment ions both as precursor and as product ions. This principle resulted in remarkable specificity and sensitivity of detection and quantification; particularly in the cases of the tetraCP and pentaCP derivatives containing the (35)Cl and the (37)Cl fragment ions at an approximate ratio of <1:1. Detailed documentation of the loss of HCl via fragmentation processes, without decomposition of the benzene ring, was attributed to the "ring-walk" mechanism described first for monochlorophenol. Critical evaluation of the derivatization and acquisition protocols was collated and validated with the same characteristics. Data of six point calibration along with the corresponding relative standard deviation percentage (RSD%) values, in the line of FS, MIM and MRM methods (r(2): 0.9987, 0.9992, 0.9989; RSD%: 8.7, 5.6, 8.1), proved to be independent on the acquisition processes. The practical utility of the optimized MRM acquisition techniques was confirmed by the quantitation of the CP contents of Danube River, tap water and distilled water samples. Results confirmed at the first time the primary importance of the MRM acquisition method, even in comparison to the MIM one: we revealed that distilled water contains higher chlorophenol content than tap water, which might have a great significance for the water industry. PMID:23834956

  16. Liquid-chromatography mass spectrometry (LC-MS) of steroid hormone metabolites and its applications

    PubMed Central

    Penning, Trevor M.; Lee, Seon-Hwa; Jin, Yi; Gutierrez, Alejandro; Blair, Ian A.

    2010-01-01

    Advances in liquid chromatography-mass spectrometry (LC-MS) can be used to measure steroid hormone metabolites in vitro and in vivo. We find that LC-Electrospray Ionization (ESI)-MS using a LCQ ion trap mass spectrometer in the negative ion mode can be used to monitor the product profile that results from 5?–dihydrotestosterone(DHT)-17?-glucuronide, DHT-17?-sulfate, and tibolone-17?-sulfate reduction catalyzed by human members of the aldo-keto reductase (AKR) 1C subfamily and assign kinetic constants to these reactions. We also developed a stable-isotope dilution LC-electron capture atmospheric pressure chemical ionization (ECAPCI)-MS method for the quantitative analysis of estrone (E1) and its metabolites as pentafluorobenzyl (PFB) derivatives in human plasma in the attomole range. The limit of detection for E1-PFB was 740 attomole on column. Separations can be performed using normal-phase LC because ionization takes place in the gas phase rather than in solution. This permits efficient separation of the regioisomeric 2- and 4-methoxy-E1. The method was validated for the simultaneous analysis of plasma E2 and its metabolites: 2-methoxy-E2, 4-methoxy-E2, 16?-hydroxy-E2, estrone (E1), 2-methoxy-E1, 4-methoxy-EI, and 16?-hydroxy-E1 from 5 pg/mL to 2,000 pg/mL. Our LC-MS methods have sufficient sensitivity to detect steroid hormone levels in prostate and breast tumors and should aid their molecular diagnosis and treatment. PMID:20083198

  17. [Determination of melamine and cyanuric acid in milk by gas chromatography-mass spectrometry].

    PubMed

    Li, Fengge; Yao, Weiqin; Su, Min; Li, Shiyu; Dou, Hui; Shang, Dejun; Zhu, Huiping

    2009-03-01

    A gas chromatography-mass spectrometry method was developed for the quantitative determination and confirmation of melamine and cyanuric acid in milk. The milk sample was extracted with diethylamine-acetonitrile-water solution. The extract was evaporated to dryness and derivatized with N, O-bis (trimethylsilyl) trifluoroacetamide (BSTFA) and chlorotrimethylsilane (TMCS), then analyzed using gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode. The external standards were used for the quantitative determination. The linear range was from 0.025 to 2 mg/kg. The average recoveries were 84%-87% for melamine and 75%-102% for cyanuric acid, and the relative standard deviations were 5.7%-11.7% for melamine and 4.9%-7.8% for cyanuric acid in the spiked levels at 0.5, 1.0 and 2.5 mg/kg. The limits of detection of melamine and cyanuric acid were 0.05 mg/kg and 0.10 mg/kg, respectively. The method is suitable for the quantitative determination and confirmation of melainine and cyanuric acid residues in milk. PMID:19626856

  18. Quantitation of opioids in whole blood by electron impact-gas chromatography-mass spectrometry.

    PubMed

    Tiscione, Nicholas B; Shan, Xiaoqin; Alford, Ilene; Yeatman, Dustin Tate

    2011-03-01

    Opioids are frequently encountered in Forensic Toxicology casework. A PubMed literature search was conducted to find a method using electron impact-gas chromatography-mass spectrometry to examine whole blood specimens. A previously published method was identified, and an updated version was provided by the State of North Carolina Office of the Chief Medical Examiner. This procedure was used as a starting point for development and validation of a refined procedure to be used in the Palm Beach County Sheriff's Office Forensic Toxicology laboratory for routine analysis of antemortem forensic toxicology case samples. Materials and instrumentation common to most forensic toxicology laboratories were utilized while obtaining detection limits from 1 to 10 ng/mL and quantitation limits of 2.5 to 10 ng/mL using 1 mL of whole blood. Target compounds were chosen based on applicability to the method as well as availability and common use in the United States and include dihydrocodeine, codeine, morphine, hydrocodone, 6-monoacetylmorphine, hydromorphone, oxycodone, and oxymorphone. Each analyte demonstrated two zero-order linear ranges (r(2) > 0.990) over the concentrations evaluated (from 2.5 to 500 ng/mL). The coefficient of variation of replicate analyses was less than 12%. Quantitative accuracy was within ± 27% at 2.5 ng/mL, ± 11% at 10 ng/mL, and ± 8% at 50 ng/mL. The validated method provides a more sensitive procedure for the quantitation of common opioids in blood using standard laboratory equipment and a small amount of sample. PMID:21396229

  19. Relative binding affinities of integrin antagonists by equilibrium dialysis and liquid chromatography-mass spectrometry.

    PubMed

    Tipping, William J; Tshuma, Nkazimulo; Adams, James; Haywood, Harvey T; Rowedder, James E; Fray, M Jonathan; McInally, Thomas; Macdonald, Simon J F; Oldham, Neil J

    2015-02-12

    The integrin ?v?6 is a potential target for treatment of idiopathic pulmonary fibrosis (IPF). Equilibrium dialysis (ED) was investigated for its ability to report ligand binding in an ?v?6 inhibitor screening assay. As a preliminary experiment, an established peptidomimetic inhibitor of the integrin was dialyzed against ?v?6, and the fraction bound (f b) and percentage saturation determined by liquid chromatography-mass spectrometry (LC-MS) analysis. Quantitation of the inhibitor in the two chambers of the ED cartridge revealed an uneven distribution in the presence of ?v?6, corresponding to near saturation binding to the protein (93 ± 3%), while the control (without integrin) showed an equal partitioning of the inhibitor on either side of the dialysis membrane. A competitive ED assay with a 12 component mixture of antagonists was conducted, and the results compared with an established cell adhesion assay for quantifying ?v?6 inhibition of individual antagonists. Compounds clustered into three groupings: those with pIC 50 values between ca. 5.0 and 5.5, which possessed ED f b values indistinguishable from the controls, those with pIC 50s of 6.5 ± 0.2, which exhibited detectable integrin binding (f b 13-25%) in the ED assay, and a single compound of pIC 50 7.2 possessing an f b value of 38%. A good correlation between ED-derived f b and pIC 50 was observed despite the two assays utilizing quite different outputs. These results demonstrate that ED with LC-MS detection shows promise as a rapid ?v?6 integrin antagonist screening assay for mixtures of putative ligands. PMID:25699153

  20. Identification of Unknown Contaminants in Water Samples from ISS Employing Liquid Chromatography/Mass Spectrometry/Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Rutz, Jeffrey A.; Schultz, John R.

    2008-01-01

    Mass Spectrometry/Mass Spectrometry (MS/MS) is a powerful technique for identifying unknown organic compounds. For non-volatile or thermally unstable unknowns dissolved in liquids, liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) is often the variety of MS/MS used for the identification. One type of LC/MS/MS that is rapidly becoming popular is time-of-flight (TOF) mass spectrometry. This technique is now in use at the Johnson Space Center for identification of unknown nonvolatile organics in water samples from the space program. An example of the successful identification of one unknown is reviewed in detail in this paper. The advantages of time-of-flight instrumentation are demonstrated through this example as well as the strategy employed in using time-of-flight data to identify unknowns.

  1. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of pesticides in water by C-18 solid-phase extraction and capillary-column gas chromatography/mass spectrometry with selected-ion monitoring

    USGS Publications Warehouse

    Zaugg, Steven D.; Sandstrom, Mark W.; Smith, Steven G.; Fehlberg, Kevin M.

    1995-01-01

    A method for the isolation of 41 pesticides and pesticide metabolites in natural-water samples using C-18 solid-phase extraction and determination by capillary-column gas chromatography/mass spectrometry with selected-ion monitoring is described. Water samples are filtered to remove suspended particulate matter and then are pumped through disposable solid-phase extraction columns containing octadecyl-bonded porous silica to extract the pesticides. The columns are dried using carbon dioxide or nitrogen gas, and adsorbed pesticides are removed from the columns by elution with 3.0 milliliters of hexane-isopropanol (3:1). Extracted pesticides are determined by capillary- column gas chromatography/mass spectrometry with selected-ion monitoring of three characteristic ions. The upper concentration limit is 4 micrograms per liter (g/L) for most pesticides, with the exception of widely used corn herbicides--atrazine, alachlor, cyanazine, and metolachlor--which have upper concentration limits of 20 g/L. Single- operator method detection limits in reagent-water samples range from 0.001 to 0.018 g/L. Average short-term single-operator precision in reagent- water samples is 7 percent at the 0.1- and 1.0-g/L levels and 8 percent at the 0.01-g/L level. Mean recoveries in reagent-water samples are 73 percent at the 0.1- and 1.0-g/L levels and 83 percent at the 0.01-g/L level. The estimated holding time for pesticides after extraction on the solid-phase extraction columns was 7 days. An optional on-site extraction procedure allows for samples to be collected and processed at remote sites where it is difficult to ship samples to the laboratory within the recommended pre-extraction holding time.

  2. A new approach to untargeted integration of high resolution liquid chromatography-mass spectrometry data.

    PubMed

    van der Kloet, Frans M; Hendriks, Margriet; Hankemeier, Thomas; Reijmers, Theo

    2013-11-01

    Because of its high sensitivity and specificity, hyphenated mass spectrometry has become the predominant method to detect and quantify metabolites present in bio-samples relevant for all sorts of life science studies being executed. In contrast to targeted methods that are dedicated to specific features, global profiling acquisition methods allow new unspecific metabolites to be analyzed. The challenge with these so-called untargeted methods is the proper and automated extraction and integration of features that could be of relevance. We propose a new algorithm that enables untargeted integration of samples that are measured with high resolution liquid chromatography-mass spectrometry (LC-MS). In contrast to other approaches limited user interaction is needed allowing also less experienced users to integrate their data. The large amount of single features that are found within a sample is combined to a smaller list of, compound-related, grouped feature-sets representative for that sample. These feature-sets allow for easier interpretation and identification and as important, easier matching over samples. We show that the automatic obtained integration results for a set of known target metabolites match those generated with vendor software but that at least 10 times more feature-sets are extracted as well. We demonstrate our approach using high resolution LC-MS data acquired for 128 samples on a lipidomics platform. The data was also processed in a targeted manner (with a combination of automatic and manual integration) using vendor software for a set of 174 targets. As our untargeted extraction procedure is run per sample and per mass trace the implementation of it is scalable. Because of the generic approach, we envision that this data extraction lipids method will be used in a targeted as well as untargeted analysis of many different kinds of TOF-MS data, even CE- and GC-MS data or MRM. The Matlab package is available for download on request and efforts are directed toward a user-friendly Windows executable. PMID:24139572

  3. Forensic discrimination of photocopy and printer toners. III. Multivariate statistics applied to scanning electron microscopy and pyrolysis gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    William J. Egan; Randolph C. Galipo; Brian K. Kochanowski; Stephen L. Morgan; Edward G. Bartick; Mark L. Miller; Dennis C. Ward; Robert F. Mothershead

    2003-01-01

    Copy toner samples were analyzed using scanning electron microscopy with X-ray dispersive analysis (SEM–EDX) and pyrolysis gas chromatography\\/mass spectrometry (Py–GC\\/MS). Principal component and cluster analysis of SEM data for 166 copy toner samples established 13 statistically different subgroups, with the presence or absence of a ferrite base being a major division. When toners were compared for which both SEM and

  4. Detecting benzodiazepines: immunoassays compared with negative chemical ionization gas chromatography/mass spectrometry.

    PubMed

    Fitzgerald, R L; Rexin, D A; Herold, D A

    1994-03-01

    We tested 231 urine samples by six immunoassay methods--EMIT d.a.u., EMIT II, Roche Abuscreen Online, Abbott TDx, Diagnostic Products Corp. (DPC) double-antibody radioimmunoassay (RIA), and Biosite Triage--and by negative chemical ionization gas chromatography/mass spectrometry to determine how the immunoassays performed on samples selected for suspected benzodiazepine use (n = 100) and in random urine drug screening (n = 131). In general, all of the assays were successful in detecting oxazepam and related metabolites, even at concentrations below the stated cutoffs. However, the negative predictive value of benzodiazepine immunoassays for samples selected for suspected benzodiazepine use ranged from 86% to 96%. A primary difference between the test kits was the ability of DPC RIA and Triage to detect lorazepam when other assays did not. Contrary to previous reports, pretreatment of specimens with glucuronidase was not necessary to detect oxazepam-related metabolites with these immunoassays. PMID:8131270

  5. [Advances of metabolite identification in liquid chromatography-mass spectrometry based metabolomics].

    PubMed

    Kong, Hongwei; Dai, Weidong; Xu, Guowang

    2014-10-01

    Liquid chromatography-mass spectrometry (LC-MS) based metabolomics has become an important approach in life science research due to its powerful separation and high sensitivity detection. However, because of the lack of an effective mass spectra library for metabolite identification, a vast amount of detected metabolites are unable to be identified. The improvement of the metabolite coverage and the discovery of biomarkers are harmed, leading to the severe loss of chemical and biological information. The metabolite identification has become a major bottleneck in metabolomics studies. This review describes recent advances of metabolite identification based on atmospheric pressure ionization (API)-MS data. In particular, it focuses on the advances in mass spectrometer instruments, assignment of elemental compositions, database and spectral search, computer-aided spectral interpretation, etc. PMID:25739265

  6. Quantification of clotiazepam in human plasma by gas chromatography-mass spectrometry.

    PubMed

    Ahn, Sung-Hoon; Maeng, Han-Joo; Koo, Tae-Sung; Kim, Dae-Duk; Shim, Chang-Koo; Chung, Suk-Jae

    2006-04-13

    An analytical procedure was developed and validated for the quantification of clotiazepam in human plasma. After subjecting plasma samples to solid-phase extraction, the extract was evaporated and the residue re-constituted. An aliquot of the mixture was injected onto a gas chromatography-mass spectrometry system. The detector response was linear for clotiazepam concentrations in the range of 5-200 ng/ml. Intra- and inter-day precision for the assay over the concentration range was below 13.1 and 13.5%, and the accuracy ranged between 99.0-107.9% and 92.4-101.3%, respectively. The drug was found to be stable under various processing conditions used. The method is applicable to human pharmacokinetic studies of clotiazepam. PMID:16517222

  7. Identification of thioketone analogues of sildenfil using gas chromatography-mass spectrometry.

    PubMed

    Man, Che Nin; Noor, Norjuliana Mohd; Lajis, Razak

    2011-09-28

    Sildenafil analogues have been found adulterated in herbal preparations and food products that claim to have natural aphrodisiacs. In this study, a gas chromatography-mass spectrometry (GC-MS) assay was developed for the screening and identification of thioketone analogues of sildenafil. Thiopyrazolopyrimidine, a precursor or a cleavage product of thioketone analogue, exhibited characteristic fragment ions of m/z 328 and m/z 299 was found to be the best marker to screen the presence of general thioketone analogues. Identification by GC-MS assay was rapid and specific as all the studied thioketones showed characteristic mass fragmentations including their intact molecular ions. The developed GC-MS assay had successfully identified thiosildenafil, thiohomosildenafil and thiodimethylsildenafil in herbal preparation and food products. PMID:21872876

  8. Rapid and sensitive liquid chromatography-mass spectrometry method for determination of ropinirole in human plasma.

    PubMed

    Bhatt, Jignesh; Jangid, Arvind; Shetty, Raghavendra; Shah, Bhavin; Kambli, Sandeep; Subbaiah, Gunta; Singh, Sadhana

    2006-03-18

    A rapid and robust liquid chromatography-mass spectrometry (LC-MS/MS) method was developed for non-ergoline dopamine D(2)-receptor agonist, ropinirole in human plasma using Es-citalopram oxalate as an internal standard. The method involves solid phase extraction from plasma, reversed-phase simple isocratic chromatographic conditions and mass spectrometric detection that enables a detection limit at picogram levels. The proposed method was validated with linear range of 20-1,200 pg/ml. The extraction recoveries for ropinirole and internal standard were 90.45 and 65.42%, respectively. The R.S.D.% of intra-day and inter-day assay was lower than 15%. For its sensitivity and reliability, the proposed method is particularly suitable for pharmacokinetic studies. PMID:16289706

  9. 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

  10. Simultaneous determination of nitrate and nitrite in human plasma by gas chromatography-mass spectrometry.

    PubMed

    Kage, Shigetoshi; Kudo, Keiko; Ikeda, Noriaki

    2002-09-01

    We devised a sensitive and simple method for the simultaneous determination of nitrate and nitrite in human plasma, using extractive alkylation. These inorganic anions were alkylated with pentafluorobenzyl bromide, using tetradecyldimethylbenzylammonium chloride as the phase-transfer catalyst, with 1,3,5-tribromobenzene as an internal standard. The derivatives were analyzed by gas chromatography-mass spectrometry, using the negative-ion chemical ionization mode with isobutane as the reagent gas. Calibration curves for nitrate and nitrite were linear over the concentration range of 0.01 to 1.0 micromol/mL in plasma, and the lower limit of detection for both compounds was 0.005 micromol/mL. The accuracy and precision of this method were evaluated and coefficients of variation were lower than 10.4%. Blood nitrate and nitrite concentrations of six victims who committed suicide by inhaling automobile exhaust gas could be determined using our method. PMID:12220012

  11. Determination of glyphosate, glyphosate metabolites, and glufosinate in human serum by gas chromatography-mass spectrometry.

    PubMed

    Motojyuku, Megumi; Saito, Takeshi; Akieda, Kazuki; Otsuka, Hiroyuki; Yamamoto, Isotoshi; Inokuchi, Sadaki

    2008-11-15

    This paper describes an assay for the determination of glyphosate (GLYP), glyphosate metabolites [(aminomethyl) phosphonic acid] (AMPA), and glufosinate (GLUF) in human serum. After protein precipitation using acetonitrile and solid-phase extraction, serum samples were derivatized and analyzed by gas chromatography-mass spectrometry (GC-MS). The assay was linear over a concentration range of 3-100.0 microg/ml for GLYP, AMPA, and GLUF. The overall recoveries for the three compounds were >73%. The intra- and inter-day variations were <15%. Precision and accuracy were 6.4-10.6% and 88.2-103.7%, respectively. The validated method was applied to quantify the GLYP and AMPA content in the serum of a GLYP-poisoned patient. In conclusion, the method was successfully applied for the determination of GLYP and its metabolite AMPA in serum obtained from patient of GLYP-poisoning. PMID:18945648

  12. Trace detection of meglumine and diatrizoate from Bacillus spore samples using liquid chromatography/mass spectrometry.

    PubMed

    Swider, Catherine; Maguire, Kelly; Rickenbach, Michael; Montgomery, Madeline; Ducote, Matthew J; Marhefka, Craig A

    2012-07-01

    Following the September 11, 2001 terrorist attacks, letters containing Bacillus anthracis were distributed through the United States postal system killing five people. A complex forensic investigation commenced to identify the perpetrator of these mailings. A novel liquid chromatography/mass spectrometry protocol for the qualitative detection of trace levels of meglumine and diatrizoate in dried spore preparations of B. anthracis was developed. Meglumine and diatrizoate are components of radiographic imaging products that have been used to purify bacterial spores. Two separate chromatographic assays using multiple mass spectrometric analyses were developed for the detection of meglumine and diatrizoate. The assays achieved limits of detection for meglumine and diatrizoate of 1.00 and 10.0 ng/mL, respectively. Bacillus cereus T strain spores were effectively used as a surrogate for B. anthracis spores during method development and validation. This protocol was successfully applied to limited evidentiary B. anthracis spore material, providing probative information to the investigators. PMID:22537353

  13. Direct quantitative determination of cyanamide by stable isotope dilution gas chromatography-mass spectrometry.

    PubMed

    Hiradate, Syuntaro; Kamo, Tsunashi; Nakajima, Eri; Kato, Kenji; Fujii, Yoshiharu

    2005-12-01

    Cyanamide is a multifunctional agrochemical used, for example, as a pesticide, herbicide, and fertilizer. Recent research has revealed that cyanamide is a natural product biosynthesized in a leguminous plant, hairy vetch (Vicia villosa). In the present study, gas chromatography-mass spectrometry (GC-MS) equipped with a capillary column for amines was used for direct quantitative determination of cyanamide. Quantitative signals for ((14)N(2))cyanamide, ((15)N(2))cyanamide (internal standard for stable isotope dilution method), and m-(trifluoromethyl)benzonitrile (internal standard for correcting errors in GC-MS analysis) were recorded as peak areas on mass chromatograms at m/z 42 (A(42)), 44 (A(44)), and 171 (A(IS)), respectively. Total cyanamide content, ((14)N(2))cyanamide plus ((15)N(2))cyanamide, was determined as a function of (A(42)+A(44))/A(IS). Contents of ((14)N(2))cyanamide and ((15)N(2))cyanamide were then calculated by multiplying the total cyanamide content by A(42)/(A(42)+A(44)) and A(44)/(A(42)+A(44)), respectively. The limit of detection for the total cyanamide content by the GC-MS analysis was around 1ng. The molar ratio of ((14)N(2))cyanamide to ((15)N(2))cyanamide in the injected sample was equal to the observed A(42)/A(44) value in the range from 0.1 to 5. It was, therefore, possible to use the stable isotope dilution method to quantify the natural cyanamide content in samples; i.e., the natural cyanamide content was derived by subtracting the A(42)/A(44) ratio of the internal standard from the A(42)/A(44) ratio of sample spiked with internal standard, and then multiplying the resulting difference by the amount of added ((15)N(2))cyanamide (SID-GC-MS method). This method successfully gave a reasonable value for the natural cyanamide content in hairy vetch, concurring with the value obtained by a conventional method in which cyanamide was derivatized to a photometrically active compound 4-cyanimido-1,2-naphthoquinone and analyzed with reversed-phase HPLC (CNQ-HPLC method). The determination range of cyanamide in the SID-GC-MS method was almost the same as that in the CNQ-HPLC method; however, the SID-GC-MS method was much simpler than the CNQ-HPLC method. PMID:16314170

  14. Characterization of volatile and semi-volatile compounds in green and fermented leaves of Bergenia crassifolia L. by gas chromatography-mass spectrometry and ID-CUBE direct analysis in real time-high resolution mass spectrometry.

    PubMed

    Chernetsova, Elena S; Shikov, Alexander N; Crawford, Elizabeth A; Grashorn, Sebastian; Laakso, I; Pozharitskaya, Olga N; Makarov, Valery G; Hiltunen, Raimo; Galambosi, Bertalan; Morlock, Gertrud E

    2014-01-01

    Chemical compositions of volatile and semi-volatile components in green and fermented leaves of Bergenia crassifolia L. were studied. Leaf components were identified using gas chromatography with low resolution mass spectrometry and direct analysis in real time (DART) high resolution mass spectrometry with an ID-CUBE ion source. Phytol, nerolidol, geraniol, linalool, alpha-bisabolol, alpha-bisabololoxide B, alpha-cadinol, delta-cadinene, alpha-terpineol and several other marker compounds of special interest were defined, for which the process of fermentation significantly changed their content in the leaves. Low resolution El GC-MS and ID-CUBE DART-HRMS were found to be complementary methods, as they provide different information, helpful to increase the confidence of identification. PMID:24895781

  15. Determination of carboxylic acids in oil samples by capillary gas chromatography/mass spectrometry

    SciTech Connect

    Shen, J.

    1981-03-01

    A combined gas chromatography/mass spectrometric (GC/MS) method for measuring carboxylic acids in oil samples without first going through solvent extraction and group separation is reported. The carboxylic acids in oils are directly derivatized to their corresponding methyl esters via anion formation in tetramethylammonium hydroxide/methanol/methyl iodide/n-butyl acetate solutions prior to GC/MS analysis using a glass wall coated capillary column. The reaction is mild, selective, and rapid. It can usually be carried out at room temperature and completed in 10 to 15 min. Multiple ion detection techniques (MID) can be readily used to further resolve methyl esters from other compounds if necessary.

  16. Comparison of the limulus amebocyte lysate test and gas chromatography-mass spectrometry for measuring lipopolysaccharides (endotoxins) in airborne dust from poultry-processing industries.

    PubMed Central

    Sonesson, A; Larsson, L; Schütz, A; Hagmar, L; Hallberg, T

    1990-01-01

    The lipopolysaccharide (endotoxin) content in airborne dust samples from three different poultry slaughterhouses was determined with both the chromogenic Limulus amebocyte lysate assay and gas chromatography-mass spectrometry analysis of lipopolysaccharide-derived 3-hydroxy fatty acids. Gram-negative cell walls were also measured by using two-dimensional gas chromatography/electron-capture analysis of diaminopimelic acid originating from the peptidoglycan. The correlation between the results of the Limulus assay and those of gas chromatography-mass spectrometry for determination of the lipopolysaccharide content in the dust samples was poor, whereas a good correlation was obtained between lipopolysaccharide and diaminopimelic acid concentrations with the gas chromatographic methods. The results suggest that it is predominantly cell-wall-dissociated lipopolysaccharides that are measured with the Limulus assay, whereas the gas chromatographic methods allow determination of total concentrations of lipopolysaccharide, including Limulus-inactive lipopolysaccharide, gram-negative cells, and cellular debris. PMID:2187411

  17. Determination of amino acids in selenium-enriched yeast by gas chromatography-mass spectrometry after microwave assisted hydrolysis.

    PubMed

    Zhang, Xu; Yang, Lu; Mester, Zoltan

    2012-09-26

    A simple, rapid microwave digestion procedure for protein hydrolysis preceding the determination of amino acids in yeast using gas chromatography-mass spectrometry (GC-MS) is described. Protein hydrolysis was performed in a focused microwave using 4M methanesulfonic acid (MAS). Amino acids were derivatized with methyl chlorofomate (MCF) and extracted into chloroform prior to GC-MS analysis. The microwave parameters, including power, temperature and heating time, were optimized. It was found that temperature and heating time were the most influential factors. A total of 17 amino acids were determined in selenium-enriched yeast with use of standard addition calibration. Limits of detection and quantitation (LODs/LOQs) of the amino acids measured were in the sub-nmol range, suitable for monitoring of amino acids in yeast and other food products. PMID:22935374

  18. Pharmacokinetic Studies of Chinese Medicinal Herbs Using an Automated Blood Sampling System and Liquid Chromatography-mass Spectrometry

    PubMed Central

    Wu, Yu-Tse; Wu, Ming-Tsang; Lin, Chia-Chun; Chien, Chao-Feng; Tsai, Tung-Hu

    2012-01-01

    The safety of herbal products is one of the major concerns for the modernization of traditional Chinese medicine, and pharmacokinetic data of medicinal herbs guide us to design the rational use of the herbal formula. This article reviews the advantages of the automated blood sampling (ABS) systems for pharmacokinetic studies. In addition, three commonly used sample preparative methods, protein precipitation, liquid-liquid extraction and solid-phase extraction, are introduced. Furthermore, the definition, causes and evaluation of matrix effects in liquid chromatography-mass spectrometry (LC/MS) analysis are demonstrated. Finally, we present our previous works as practical examples of the application of ABS systems and LC/MS for the pharmacokinetic studies of Chinese medicinal herbs. PMID:24716112

  19. Identification and quantitation of glycosidically bound aroma compounds in three tobacco types by gas chromatography-mass spectrometry.

    PubMed

    Cai, Kai; Xiang, Zhangmin; Pan, Wenjie; Zhao, Huina; Ren, Zhu; Lei, Bo; Geng, Zhaoliang

    2013-10-11

    Glycosidically bound aroma compounds in three different types of tobacco were investigated. After isolation of extracts obtained by Amberlite XAD-2 adsorption and ethyl acetate elution, glycosides were analyzed after enzymatic hydrolysis by gas chromatography-mass spectrometry (GC-MS) or directly after trifluoroacetylated (TFA) derivatization by GC-MS in electron ionization (EI) and negative chemical ionization (NCI) mode. In total 21 bound aglycones were identified by ?-glucosidase hydrolysis. These aglycones mainly consisted of C13-norisoprenoids, aromatic components and sesquiterpenoids. Additionally, with the aid of enzymatic hydrolysis, 15 ?-d-glucopyranosides and 1 ?-d-rutinoside were tentatively identified by TFA derivatization. TFA method was validated by repeatability and successfully employed to analyze different types of tobacco. Principal component analysis (PCA) was carried out on identified glycoside variables to visualize the difference between the tobacco types and the relationship between the glycoside variables and the tobacco types was established. PMID:24011421

  20. Characterisation of compounds emitted during natural and artificial ageing of a book. Use of headspace-solid-phase microextraction\\/gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    Agnès Lattuati-Derieux; Sylvette Bonnassies-Termes; Bertrand Lavédrine

    2006-01-01

    An optimised headspace-solid-phase microextraction (HS-SPME) coupled with a gas chromatography\\/mass spectrometry (GC\\/MS) method has been applied to the analysis of volatile organic compounds (VOCs) emitted from a groundwood pulp book naturally and artificially aged. In order to assess the potentiality of HS-SPME for accessing the compounds produced during the degradation of paper, two different accelerated ageing treatments were applied on

  1. Gas chromatography-mass spectrometry (GC-MS) method for the determination of 16 European priority polycyclic aromatic hydrocarbons in smoked meat products and edible oils

    Microsoft Academic Search

    W. Jira; K. Ziegenhals; K. Speer

    2008-01-01

    A gas chromatography-mass spectrometry (GC-MS) method was developed for the analysis of 15 polycyclic aromatic hydrocarbons (PAHs) highlighted as carcinogenic by the Scientific Committee on Food (SCF) plus benzo[c]fluorine (recommended to be analysed by the Joint FAO\\/WHO Expert Committee on Food Additives (JECFA)) in fat-containing foods such as edible oils and smoked meat products. This method includes accelerated solvent extraction

  2. Use of gas chromatography–mass spectrometry combined with resolution methods to characterize the essential oil components of Iranian cumin and caraway

    Microsoft Academic Search

    Mehdi Jalali-Heravi; Behrooz Zekavat; Hassan Sereshti

    2007-01-01

    Gas chromatography–mass spectrometry combined with iterative and non-iterative resolution methods was used to characterize the essential oil components of Iranian cumin and caraway. Orthogonal projection resolution (OPR) as a non-iterative and distance-selection-multivariate curve resolution-alternative least squares (DS-MCR-ALS) as an iterative method were used as auxiliary means to the analysis in the case of overlapping peaks. A total of 19 and

  3. Simultaneous determination of the endocrine disrupting compounds nonylphenol, nonylphenol ethoxylates, triclosan and bisphenol A in wastewater and sewage sludge by gas chromatography–mass spectrometry

    Microsoft Academic Search

    Georgia Gatidou; Nikolaos S. Thomaidis; Athanasios S. Stasinakis; Themistokles D. Lekkas

    2007-01-01

    An integrated analytical method for the simultaneous determination of 4-n-nonylphenol (4-n-NP), nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO), bisphenol A (BPA) and triclosan (TCS) in wastewater (dissolved and particulate phase) and sewage sludge was developed based on gas chromatography–mass spectrometry. Chromatographic analysis was achieved after derivatization with bis(trimethylsilyl)trifluoroacetamide (BSTFA). Extraction from water samples was performed by solid-phase extraction (SPE). The optimization

  4. Determination of nitrated polycyclic aromatic hydrocarbons in diesel particulate-related standard reference materials by using gas chromatography\\/mass spectrometry with negative ion chemical ionization

    Microsoft Academic Search

    Dawit Z. Bezabeh; Holly A. Bamford; Michele M. Schantz; Stephen A. Wise

    2003-01-01

    Gas chromatography\\/mass spectrometry (GC\\/MS) with negative ion chemical ionization (NICI) detection was utilized for quantitative determination of nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) in diesel particulate-related standard reference materials (SRMs). Prior to GC\\/MS analysis, isolation of the nitro-PAHs from the complex diesel particulate extract was accomplished using solid phase extraction (SPE) and normal-phase liquid chromatographic (LC) fractionation using an amino\\/cyano stationary

  5. A gas chromatography–mass spectrometry method for the measurement of fatty acid ? and ? ?1 hydroxylation kinetics by CYP4A1 using an artificial membrane system

    Microsoft Academic Search

    Victoria E. Holmes; Mary Bruce; P. Nicholas Shaw; David R. Bell; Fan Ming Qi; David A. Barretta

    2004-01-01

    A gas chromatography–mass spectrometry assay method for the analysis of lauric, myristic, and palmitic acids and their ? and ??1 hydroxylated metabolites from in vitro incubations of cytochrome P450 CYP4A1, involving solid-phase extraction and trimethysilyl derivatization, was developed. The assay was linear, precise, and accurate over the range 0.5 to 50?M for all the analytes. It has the advantages of

  6. THE IDENTIFICATION OF POLYCHLORINATED TERPHENYLS AT TRACE LEVELS IN HUMAN ADIPOSE TISSUE BY GAS CHROMATOGRAPHY/MASS SPECTROMETRY

    EPA Science Inventory

    Pooled samples of human adipose extracts representative of the general population of the United States were examined by gas chromatography-mass spectrometry. The use of gel permeation chromatography for cleanup was found to offer a significant improvement in detection capability....

  7. Liquid chromatography–mass spectrometry in occupational toxicology: A novel approach to the study of biotransformation of industrial chemicals

    Microsoft Academic Search

    Paola Manini; Roberta Andreoli; Wilfried M. A. Niessen

    2004-01-01

    Biological monitoring and biomarkers are used in occupational toxicology for a more accurate risk assessment of occupationally exposed people. Appropriate and validated biomarkers of internal dose, like urinary metabolites, besides to be positively correlated with external exposure, have a predictive value to the risk of adverse effects. The application of liquid chromatography–mass spectrometry (LC–MS) in occupational and environmental toxicology, although

  8. Determination of cocaine, benzoylecgonine and cocaethylene in human hair by solid-phase microextraction and gas chromatography–mass spectrometry

    Microsoft Academic Search

    Fernanda Crossi Pereira de Toledo; Mauricio Yonamine; Regina Lucia de Moraes Moreau; Ovandir Alves Silva

    2003-01-01

    The present work describes a highly precise and sensitive method developed to detect cocaine (COC), benzoylecgonine (BE, its main metabolite) and cocaethylene (CE, transesterification product of the coingestion of COC with ethanol) in human head hair samples. The method was based on an alkylchloroformate derivatization of benzoylecgonine and the extraction of the analytes by solid-phase microextraction (SPME). Gas chromatography–mass spectrometry

  9. Picomolar concentrations of morphine in human urine determined by dansyl derivatization and liquid chromatography–mass spectrometry

    Microsoft Academic Search

    Marc Lamshöft; Nadja Grobe; Michael Spiteller

    2011-01-01

    Morphine is present in varying amounts as an endogenous product in human urine. Derivatization of morphine contained in urine with dansyl chloride yields a known product, which can be quantified by liquid chromatography mass spectrometry with high selectivity and sensitivity. Urine samples of 51 healthy individuals were spiked with stable-isotope labeled morphine, hydrolyzed and subjected to solid phase extraction followed

  10. Identification of wild collected mosquito vectors of diseases using gas chromatography-mass spectrometry in Jazan Province, Saudi Arabia.

    PubMed

    Al Ahmed, Azzam M; Badjah-Hadj-Ahmed, Ahmed-Yacine; Al Othman, Zeid A; Sallam, Mohamed F

    2013-11-01

    Thirty-three species of mosquitoes have been reported from the Kingdom of Saudi Arabia. Several of these mosquitoes, Anopheles gambiae Giles s.l., Anopheles stephensi Liston, Culex pipiens Linnaeus, Culex quinquefasciatus Say, Culex tritaeniorhynchus Giles, Stegomyia aegypti (Linnaeus) and Aedimorphus vexans arabiensis (Patton) are known vectors of human and animal diseases. In this study, the cuticular hydrocarbon profiles of eight mosquito species using gas chromatography-mass spectrometry were analyzed. Wild collected fourth-instar larvae were reared, and single, newly emerged, unfed adult females were used for the analysis. A total of 146-160 peaks were detected from the cuticular extracts by gas chromatography. Repeated analysis of variance (ANOVA) and Tukey HSD Post Hoc test was used to test for quantitative differences in relative hydrocarbon quantity. In addition, a linear regression model was applied using Enter method to determine the diagnostic peaks for the eight mosquito specimens. The ANOVA test indicated that relative peaks were significant (P < 0.05) when selected pairs of peaks were compared. Also, seven compounds showed qualitative differences among the five mosquito vectors tested. The classes of constituents present were n-alkanes, monomethylalkanes, dimethylalkanes, trimethylalkanes, alkenes, branched aromatic hydrocarbons, aldehydes and esters. These compounds have a carbon chain length ranging from 8 to 18 carbons. The most abundant compound in all adult mosquito specimens was n-hexylacrylate [retention time (RT) 6.73 min], which was not detected in Cx. pipiens. In Cx. pipiens, the most abundant peak was benzaldehyde (RT 2.98 min). Gas chromatography-mass spectrometry is a suitable method to identify adult mosquitoes, especially from focal areas of public health concern such as Jazan Province, Saudi Arabia. This method allows a wide range of adult collected material to be identified with high accuracy. PMID:24259205

  11. Isotope ratio monitoring gas chromatography/Mass spectrometry of D/H by high temperature conversion isotope ratio mass spectrometry.

    PubMed

    Hilkert; Douthitt; Schlüter; Brand

    1999-07-01

    Of all the elements, hydrogen has the largest naturally occurring variations in the ratio of its stable isotopes (D/H). It is for this reason that there has been a strong desire to add hydrogen to the list of elements amenable to isotope ratio monitoring gas chromatography/mass spectrometry (irm-GC/MS). In irm-GC/MS the sample is entrained in helium as the carrier gas, which is also ionized and separated in the isotope ratio mass spectrometer (IRMS). Because of the low abundance of deuterium in nature, precise and accurate on-line monitoring of D/H ratios with an IRMS requires that low energy helium ions be kept out of the m/z 3 collector, which requires the use of an energy filter. A clean mass 3 (HD(+.)) signal which is independent of a large helium load in the electron impact ion source is essential in order to reach the sensitivity required for D/H analysis of capillary GC peaks. A new IRMS system, the DELTA(plus)XL(trade mark), has been designed for high precision, high accuracy measurements of transient signals of hydrogen gas. It incorporates a retardation lens integrated into the m/z 3 Faraday cup collector. Following GC separation, the hydrogen bound in organic compounds must be quantitatively converted into H(2) gas prior to analysis in the IRMS. Quantitative conversion is achieved by high temperature conversion (TC) at temperatures >1400 degrees C. Measurements of D/H ratios of individual organic compounds in complicated natural mixtures can now be made to a precision of 2 per thousand (delta notation) or, better, with typical sample amounts of approximately 200 ng per compound. Initial applications have focused on compounds of interest to petroleum research (biomarkers and natural gas components), food and flavor control (vanillin and ethanol), and metabolic studies (fatty acids and steroids). Copyright 1999 John Wiley & Sons, Ltd. PMID:10407302

  12. Non-targeted metabolomics study for the analysis of chemical compositions in three types of tea by using gas chromatograph-mass spectrometry and liquid chromatography-mass spectrometry.

    PubMed

    Zhang, Lei; Zeng, Zhongda; Ye, Guozhu; Zhao, Chunxia; Lu, Xin; Xu, Guowang

    2014-08-01

    Tea is one of the most widely consumed beverages in the world for its benefits to daily life and health. To discover the difference and correlation of chemical compositions in the three typical types of tea, a non-targeted metabolomics method was developed. After the optimization of extraction methods, gas chromatography-time-of-flight mass spectrometry and liquid chromatography-quadrupole time-of-flight mass spectrometry were applied for metabolomics analysis, 1,812 and 2,608 features were obtained, respectively. By comparing with the known compounds in public and/or commercial databases, 173 compounds were tentatively identified, and 109 of them were experimentally confirmed by standards. Totally, 33 tea samples including 12, 12 and 9 samples of green, oolong and black tea, respectively, were analyzed by using the above two methods. Multivatiate analysis, Mann-Whitney U test and hierarchical cluster analysis were used to find and visualize the differential components in the three types of tea. Finally, 90 compounds, which contain catechins, amino acids, organic acids, flavonol glycosides, alkaloids, carbohydrates, lipids, etc, were found with a significant difference among them. This study demonstrates the potentials and power of metabolomics methods to understand the chemical secrets of tea. This should help a lot to optimize the processes of agriculture, storage, preparation and consumption. PMID:25434114

  13. Determination of polycyclic and nitro musks in environmental water samples by means of microextraction by packed sorbents coupled to large volume injection-gas chromatography-mass spectrometry analysis.

    PubMed

    Cavalheiro, J; Prieto, A; Monperrus, M; Etxebarria, N; Zuloaga, O

    2013-04-22

    In this work the development and validation of a new procedure for the simultaneous determination of 9 nitro and polycyclic musk compounds: musk ambrette (MA), musk ketone (MK), musk mosken (MM), celestolide (ADBI), phantolide (AHMI), tonalide (AHTN), traseolide (ATII), cashmeran (DPMI) and galaxolide (HHCB) in environmental water samples (estuarine and wastewater) using microextraction by packed sorbent (MEPS) followed by large volume injection-gas chromatography-mass spectrometry (LVI-GC-MS) was carried out. Apart from the optimization of the different variables affecting MEPS (i.e., nature of the sorbent, nature of the solvent elution, sample load, and elution/injection volume) extraction recovery was also evaluated, not only for water samples but also for environmental water matrices such as estuarine and waste water. The use of two deuterated analogs ([(2)H3]-AHTN and [(2)H15]-MX) was successfully evaluated in order to correct matrix effect in complex environmental matrices such as influent samples from wastewater treatment plants. Method detection limits (MDLs) ranged from 5 to 25 ng L(-1), 7 to 39 ng L(-1) and 8 to 84 ng L(-1) for influent, effluent and estuarine samples, respectively. Apparent recoveries were higher than 75% for all target compounds in all the matrices studied (estuarine water and wastewater) and the precision of the method, calculated as relative standard deviation (RSD), was below 13.2% at 200 ng L(-1) concentration level and below 14.9% at low level (20 ng L(-1) for all the target analytes, except for AHTN which was set at 40 ng L(-1) and HHCB at 90 ng L(-1), due to the higher MDL values presented by those target compounds). Finally, this MEPS procedure was applied to the determination of the target analytes in water samples, including estuarine and wastewater, from two estuaries, Urdaibai (Spain) and Adour (France) and an established stir-bar sorptive extraction-liquid desorption/large volume injection-gas chromatography-mass spectrometry (SBSE-LD/LVI-GC-MS) method was performed in parallel for comparison. Results were in good agreement for all the analytes determined, except for DPMI. PMID:23561908

  14. Direct quantification of dimethylsulfoniopropionate (DMSP) with hydrophilic interaction liquid chromatography/mass spectrometry.

    PubMed

    Spielmeyer, Astrid; Pohnert, Georg

    2010-12-01

    A simple, derivatization free method for the direct determination of dimethylsulfoniopropionate (DMSP) using hydrophilic interaction liquid chromatography (HILIC)/mass spectrometry is introduced. DMSP is a zwitterionic osmolyte which is produced from marine plankton, macro algae and higher plants. Due to its central role in climate relevant geochemical processes as well as in plant physiology and chemical ecology there is a great interest in methods for its quantification. Since DMSP is labile and difficult to extract currently most protocols for quantification are based on indirect methods. Here we show that ultra performance liquid chromatography/mass spectrometry using a HILIC stationary phase is suitable for the direct quantification of DMSP from aqueous samples and microalgal extracts. The protocol requires minimal sample preparation and phytoplankton samples can be investigated after filtration of small volumes. The limit of detection is 20nM and the calibration curve is linear in the range of 60nM to 50?M. The use of [(2)H(6)]-DMSP as internal standard allows prolonged sample storage since it is transformed with the same kinetics as natural DMSP. This makes the method suitable for both laboratory and field studies. PMID:21030323

  15. Method of analysis and quality-assurance practices by the U.S. Geological Survey Organic Geochemistry Research Group; determination of geosmin and methylisoborneol in water using solid-phase microextraction and gas chromatography/mass spectrometry

    USGS Publications Warehouse

    Zimmerman, L.R.; Ziegler, A.C.; Thurman, E.M.

    2002-01-01

    A method for the determination of two common odor-causing compounds in water, geosmin and 2-methylisoborneol, was modified and verified by the U.S. Geological Survey's Organic Geochemistry Research Group in Lawrence, Kansas. The optimized method involves the extraction of odor-causing compounds from filtered water samples using a divinylbenzene-carboxen-polydimethylsiloxane cross-link coated solid-phase microextraction (SPME) fiber. Detection of the compounds is accomplished using capillary-column gas chromatography/mass spectrometry (GC/MS). Precision and accuracy were demonstrated using reagent-water, surface-water, and ground-water samples. The mean accuracies as percentages of the true compound concentrations from water samples spiked at 10 and 35 nanograms per liter ranged from 60 to 123 percent for geosmin and from 90 to 96 percent for 2-methylisoborneol. Method detection limits were 1.9 nanograms per liter for geosmin and 2.0 nanograms per liter for 2-methylisoborneol in 45-milliliter samples. Typically, concentrations of 30 and 10 nanograms per liter of geosmin and 2-methylisoborneol, respectively, can be detected by the general public. The calibration range for the method is equivalent to concentrations from 5 to 100 nanograms per liter without dilution. The method is valuable for acquiring information about the production and fate of these odor-causing compounds in water.

  16. Non-targeted metabolomics study for the analysis of chemical compositions in three types of tea by using gas chromatograph-mass spectrometry and liquid chromatography-mass spectrometry.

    PubMed

    Zhang, Lei; Zeng, Zhongda; Ye, Guozhu; Zhao, Chunxia; Lu, Xin; Xu, Guowang

    2014-08-01

    Tea is one of the most widely consumed beverages in the world for its benefits to daily life and health. To discover the difference and correlation of chemical compositions in the three typical types of tea, a non-targeted metabolomics method was developed. After the optimization of extraction methods, gas chromatography-time-of-flight mass spectrometry and liquid chromatography-quadrupole time-of-flight mass spectrome- try were applied for metabolomics analysis, 1,812 and 2,608 features were obtained, respectively. By comparing with the known compounds in public and/or commercial databases, 173 compounds were tentatively identified, and 109 of them were experimentally confirmed by standards. Totally, 33 tea samples including 12, 12 and 9 samples of green, oolong and black tea, respectively, were analyzed by using the above two methods. Multivatiate analysis, Mann-Whitney U test and hierarchical cluster analysis were used to find and visualize the differential components in the three types of tea. Finally, 90 compounds, which contain catechins, amino acids, organic acids, flavonol glycosides, alkaloids, carbohydrates, lipids, etc, were found with a significant difference among them. This study demonstrates the potentials and power of metabolomics methods to understand the chemical secrets of tea. This should help a lot to optimize the processes of agriculture, storage, preparation and consumption. PMID:25507712

  17. Investigation of Volatile Compounds in Two Raspberry Cultivars by Two Headspace Techniques: SolidPhase Microextraction\\/Gas Chromatography-Mass Spectrometry (SPME\\/GC-MS) and Proton-Transfer Reaction-Mass Spectrometry (PTR-MS)

    Microsoft Academic Search

    Eugenio Aprea; Franco Biasioli; Silvia Carlin; Isabella Endrizzi; Flavia Gasperi

    2009-01-01

    The volatile compounds emitted by two raspberry varieties {(Rubus} idaeus, cv. Polka and Tulameen) were analyzed, in both the case of fresh fruits and juices, by two headspace methods that are rapid, solvent-free, and with reduced or no sample pretreatment: solid-phase microextraction\\/gas chromatography-mass spectrometry {(SPME\\/GC-MS)} and proton-transfer reaction-mass spectrometry {(PTR-MS).} Multivariate analysis of the {SPME\\/GC-MS} results allows for an unambiguous

  18. Occurrence of short chain aliphatic diols in human blood: identification by gas chromatography-mass spectrometry.

    PubMed

    Sisfontes, L; Nyborg, G; Jones, A W; Blomstrand, R

    1986-03-16

    Patients attending a general hospital for various reasons were screened for raised serum gamma glutamyltransferase (gamma-GT) and positive blood alcohol concentration (BAC). The results served as objective biochemical tests of heavy drinking. Among 419 individuals, 50 (11.9%) met these requirements and blood samples were used to determine the presence of low molecular mass aliphatic diols. 1,2-Propanediol, 2,3-butanediol and 2,2-dimethyl-1,3-propanediol were determined by gas liquid chromatography-mass spectrometry (GC-MS). In patients with blood ethanol concentration less than 2 mmol/l, 1,2-propanediol and 2,2-dimethyl-1, 3-propanediol mainly occurred together at median concentrations of about 200 mumol/l. When blood ethanol was 2-42 mmol/1,2,3-butanediol was also present covering a wide concentration range: three patients had concentrations between 6 and 10 mmol/l. There was no apparent correlation between the concentration of 2,3-butanediol and the concentration of blood ethanol. The diols were below the limits of detection in blood from nonintoxicated control individuals and hospital in-patients. PMID:3698310

  19. Quantification of busulfan in plasma by gas chromatography-mass spectrometry following derivatization with tetrafluorothiophenol.

    PubMed

    Quernin, M H; Poonkuzhali, B; Montes, C; Krishnamoorthy, R; Dennison, D; Srivastava, A; Vilmer, E; Chandy, M; Jacqz-Aigrain, E

    1998-05-01

    A specific and highly sensitive method has been developed for the determination of busulfan in plasma by gas chromatography-mass spectrometry using a deuterium-labeled busulfan (busulfan-d8) as internal standard. Plasma containing busulfan and busulfan-d8 were extracted with ethyl acetate and derivatized with 2,3,5,6-tetrafluorothiophenol prior to the monitoring of specific ions. The limit of quantification of the assay was 20 ng/ml and the calibration curve was linear over the range of 10 to 2000 ng/ml of derivatized busulfan. This method was in good agreement with the GC-MS assay using derivatization with sodium iodide and measuring diiodobutane. In addition, a pharmacokinetic study of busulfan was conducted in six children. The apparent oral clearance was 5.7+/-1.9 ml/kg/min and the volume of distribution was 1.0+/-0.4 l/kg and were similar to those previously reported in pediatric patients. PMID:9653925

  20. Chemical discrimination in turbulent gas mixtures with MOX sensors validated by gas chromatography-mass spectrometry.

    PubMed

    Fonollosa, Jordi; Rodríguez-Luján, Irene; Trincavelli, Marco; Vergara, Alexander; Huerta, Ramón

    2014-01-01

    Chemical detection systems based on chemo-resistive sensors usually include a gas chamber to control the sample air flow and to minimize turbulence. However, such a kind of experimental setup does not reproduce the gas concentration fluctuations observed in natural environments and destroys the spatio-temporal information contained in gas plumes. Aiming at reproducing more realistic environments, we utilize a wind tunnel with two independent gas sources that get naturally mixed along a turbulent flow. For the first time, chemo-resistive gas sensors are exposed to dynamic gas mixtures generated with several concentration levels at the sources. Moreover, the ground truth of gas concentrations at the sensor location was estimated by means of gas chromatography-mass spectrometry. We used a support vector machine as a tool to show that chemo-resistive transduction can be utilized to reliably identify chemical components in dynamic turbulent mixtures, as long as sufficient gas concentration coverage is used. We show that in open sampling systems, training the classifiers only on high concentrations of gases produces less effective classification and that it is important to calibrate the classification method with data at low gas concentrations to achieve optimal performance. PMID:25325339

  1. [15N]aspartate metabolism in cultured astrocytes. Studies with gas chromatography-mass spectrometry.

    PubMed Central

    Yudkoff, M; Nissim, I; Pleasure, D

    1987-01-01

    The metabolism of 2.5 mM-[15N]aspartate in cultured astrocytes was studied with gas chromatography-mass spectrometry. Three primary metabolic pathways of aspartate nitrogen disposition were identified: transamination with 2-oxoglutarate to form [15N]glutamate, the nitrogen of which subsequently was transferred to glutamine, alanine, serine and ornithine; condensation with IMP in the first step of the purine nucleotide cycle, the aspartate nitrogen appearing as [6-amino-15N]adenine nucleotides; condensation with citrulline to form argininosuccinate, which is cleaved to yield [15N]arginine. Of these three pathways, the formation of arginine was quantitatively the most important, and net nitrogen flux to arginine was greater than flux to other amino acids, including glutamine. Notwithstanding the large amount of [15N]arginine produced, essentially no [15N]urea was measured. Addition of NaH13CO3 to the astrocyte culture medium was associated with the formation of [13C]citrulline, thus confirming that these cells are capable of citrulline synthesis de novo. When astrocytes were incubated with a lower (0.05 mM) concentration of [15N]aspartate, most 15N was recovered in alanine, glutamine and arginine. Formation of [6-amino-15N]adenine nucleotides was diminished markedly compared with results obtained in the presence of 2.5 mM-[15N]aspartate. PMID:3032154

  2. Bioequivalence of nifedipine softgel and capsule in healthy Chinese volunteers by liquid chromatography-mass spectrometry.

    PubMed

    Zhang, Jing; Song, Hao-Jing; Bu, Fan-Long; Wei, Chun-Min; Yuan, Gui-Yan; Liu, Xiao-Yan; Wang, Ben-Jie; Guo, Rui-Chen

    2010-09-01

    The study aimed to compare and evaluate the bioequivalence of Calcigard-10 softgel and Adalat 10 capsule in healthy Chinese volunteers in a randomized, two-way cross over study design with a washout period of 7 days. A sensitive and reproducible electro-spray ionization liquid chromatography-mass spectrometry (ESI-LCMS) assay was developed and validated to determine nifedipine in human plasma using nitrendipine as internal standard. Nifedipine and nitrendipine were extracted from plasma using liquid-liquid extraction with methylene chloride as extraction solvent. The separation was performed by a Diamonsil ODS column (150 x 4.6 mm, 5 microm). The mobile phase was consisted of acetonitrile-5 mM ammonium acetate (52:48, v/v), delivered at flow rate of 1 mL/min. The 90% confidence intervals for the ratio values of logarithmic transformed Cmax and AUC were calculated to evaluate the bioequivalence of two preparations. The values of Cmax (92.3-112.7%), AUC0-t (84.5-95.1%) and AUC0-inf (84.4-95.5%) are within the interval criterion of 70-143% for Cmax and 80-125% for AUC. The Calcigard-10 softgel and Adalat 10 capsule are bioequivalent. PMID:21495269

  3. Determination of free and ethoxylated alkylphenols in leather with gas chromatography-mass spectrometry.

    PubMed

    Ma, He-Wei; Cheng, Ya

    2010-12-10

    An analytical approach was developed to determine nonylphenol (NP), octylphenol (OP), nonylphenol ethoxylates (NPEO(n)) and octylphenol ethoxylates (OPEO(n)) in leather samples involving the conversion of NPEO(n) and OPEO(n) into the corresponding NP and OP. The four targets were extracted from samples using ultrasonic-assisted acetonitrile extraction. NP and OP in the extracts were directly isolated with hexane and quantitatively determined with 4-n-nonylphenol as internal standard by gas chromatography-mass spectrometry (GC-MS). For NPEO(n) and OPEO(n) in the extracts, they were first converted into NP and OP with aluminum triiodide as cleavage agent, and the yielded NP and OP were determined by GC-MS. The contents of NPEO(n) and OPEO(n) were calculated by normalizing to NPEO(9) and OPEO(9), respectively. This method was properly validated and the real sample tests revealed the pollution significance of leather by NPEO(n) and OPEO(n). PMID:21067757

  4. Gas chromatography-mass spectrometry/selected ion monitoring for screening asymmetric epoxidation of styrene.

    PubMed

    Mu, Yao; Wei, Siping; Xu, Min; Chen, Ping; Wang, Qin; Du, Xi

    2014-12-01

    A screening method by gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring (SIM) has been developed for asymmetric epoxidation of styrene. All samples were analyzed by GC-MS with the mode of SIM by using ethylbenzene as the internal standard, by which styrene and styrene epoxide enantiomers were completely separated and their concentrations were accurately determined. Furthermore, this method was used to evaluate the epoxidation reaction of styrene, which was optimized by orthogonal experiment. The advantages of the method are as follows: excellent precision (RSD in the range of 1. 2% - 5. 2%, n= 5), good linearity (the correlation coefficients for styrene, (R)/(S)-styrene oxide were 0. 9997, 0. 9932 and 0. 9963, respectively) , low limits of quantitation (LOQs of styrene, (R)/(S)-styrene oxide were 1. 3, 1. 1 and 0. 7 mg/L, respectively) and reasonable recoveries (98. 2% - 108. 2%). All in all, the method provided a new way to determine the asymmetric epoxidation mixture of styrene and its homologs. PMID:25902648

  5. Determination of ajulemic acid and its glucuronide in human plasma by gas chromatography-mass spectrometry.

    PubMed

    Batista, Catarina; Berisha, Myftar; Karst, Matthias; Salim, Kahlid; Schneider, Udo; Brenneisen, Rudolf

    2005-06-01

    A method using gas chromatography-mass spectrometry (GC-MS) and solid-phase extraction (SPE) was developed for the determination of ajulemic acid (AJA), a non-psychoactive synthetic cannabinoid with interesting therapeutic potential, in human plasma. When using two calibration graphs, the assay linearity ranged from 10 to 750 ng/ml, and 750 to 3000 ng/ml AJA. The intra- and inter-day precision (R.S.D., %), assessed across the linear ranges of the assay, was between 1.5 and 7.0, and 3.6 and 7.9, respectively. The limit of quantitation (LOQ) was 10 ng/ml. The amount of AJA glucuronide was determined by calculating the difference in the AJA concentration before ("free AJA") and after enzymatic hydrolysis ("total AJA"). The present method was used within a clinical study on 21 patients suffering from neuropathic pain with hyperalgesia and allodynia. For example, plasma levels of 599.4+/-37.2 ng/ml (mean+/-R.S.D., n=9) AJA were obtained for samples taken 2 h after the administration of an oral dose of 20 mg AJA. The mean AJA glucuronide concentration at 2h was 63.8+/-127.9 ng/ml. PMID:15866495

  6. Determination of chloramphenicol residues in milk, eggs, and tissues by liquid chromatography/mass spectrometry.

    PubMed

    Penney, Lisa; Smith, Anderson; Coates, Brent; Wijewickreme, Arosha

    2005-01-01

    A new liquid chromatography/mass spectrometry (LC/MS) method is presented for the determination of chloramphenicol (CAP) residues in milk, eggs, chicken muscle and liver, and beef muscle and kidney. CAP is extracted from the samples with acetonitrile and defatted with hexane. The acetonitrile extracts are then evaporated, and residues are reconstituted in 10mM ammonium acetate--acetonitrile mobile phase and injected into the LC system. CAP is determined by reversed-phase chromatography using an Inertsil ODS-2 column and MS detection with negative ion electrospray ionization. Calibration curves were linear between 0.5-5.0 ng/g for all matrixes studied. The relative standard deviations for measurements by this method were generally <12%, and average recoveries ranged from 80 to 120%, depending on the matrix involved. The method detection limits of CAP ranged from 0.2 to 0.6 ng/g, which are comparable to previously reported results. The proposed method is rapid, simple, and specific, allowing a single analyst to easily prepare over 40 samples in a regular working day. PMID:15859093

  7. Simultaneous determination of quinolone antibacterials in bovine milk by liquid chromatography-mass spectrometry.

    PubMed

    Zafra-Gómez, Alberto; Garballo, Antonio; Ballesteros, Oscar; Navalón, Alberto; García-Ayuso, Luís E

    2008-11-01

    A new liquid chromatography-mass spectrometry (LC-MS) method has been developed and validated for the simultaneous determination of eight quinolone antibacterials for veterinary use in processed bovine milk samples. The quinolones studied included marbofloxacin, ciprofloxacin, danofloxacin, enrofloxacin, sarafloxacin, difloxacin, oxolinic acid and flumequine. Also, a new sample-treatment procedure was used for extraction and preconcentration of these compounds. It involved defatting by centrifugation, protein precipitation by adding a mixture of glacial acetic acid-acetonitrile and removing acetonitrile with dichloromethane; finally, the acidified aqueous layer was evaporated to dryness in a speed vac system, resuspended in the mobile phase and filtered prior to LC injection. The mobile phase was composed of a formic acid aqueous solution 0.1% (v/v) and acetonitrile, with an initial composition of water-acetonitrile 95: 5 (v/v) and using linear gradient elution. Norfloxacin was used as internal standard. The limits of quantification found (2-7 ng g(-1)) were in all cases lower than the maximum residue limits tolerated by the European Union for these compounds in milk. PMID:18651586

  8. Disposition of the Herbicide 2-Chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (Atrazine) and Its Major Metabolites in Mice: A Liquid Chromatography/Mass Spectrometry Analysis of Urine, Plasma, and Tissue Levels

    PubMed Central

    Ross, Matthew K.; Jones, Toni L.; Filipov, Nikolay M.

    2009-01-01

    2-Chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine, ATR) is a toxicologically important and widely used herbicide. Recent studies have shown that it can elicit neurological, immunological, developmental, and biochemical alterations in several model organisms, including in mice. Because disposition data in mice are lacking, we evaluated ATR's metabolism and tissue dosimetry after single oral exposures (5–250 mg/kg) in C57BL/6 mice using liquid chromatography/mass spectrometry (Ross and Filipov, 2006). ATR was metabolized and cleared rapidly; didealkyl ATR (DACT) was the major metabolite detected in urine, plasma, and tissues. Plasma ATR peaked at 1 h postdosing and rapidly declined, whereas DACT peaked at 2 h and slowly declined. Most ATR and metabolite residues were excreted within the first 24 h. However, substantial amounts of DACT were still present in 25- to 48-h and 49- to 72-h urine. ATR reached maximal brain levels (0.06–1.5 ?M) at 4 h (5–125 mg/kg) and 1 h (250 mg/kg) after dosing, but levels quickly declined to <0.1 ?M by 12 h in all the groups. In contrast, strikingly high concentrations of DACT (1.5–50 ?M), which are comparable with liver DACT levels, were detectable in brain at 2 h. Brain DACT levels slowly declined, paralleling the kinetics of plasma DACT. Our findings suggest that in mice ATR is widely distributed and extensively metabolized and that DACT is a major metabolite detected in the brain at high levels and is ultimately excreted in urine. Our study provides a starting point for the establishment of models that link target tissue dose to biological effects caused by ATR and its in vivo metabolites. PMID:19116264

  9. Monitoring of atmospheric gaseous and particulate polycyclic aromatic hydrocarbons in South African platinum mines utilising portable denuder sampling with analysis by thermal desorption-comprehensive gas chromatography-mass spectrometry.

    PubMed

    Geldenhuys, G; Rohwer, E R; Naudé, Y; Forbes, P B C

    2015-02-01

    Concentrations of diesel particulate matter and polycyclic aromatic hydrocarbons (PAHs) in platinum mine environments are likely to be higher than in ambient air due to the use of diesel machinery in confined environments. Airborne PAHs may be present in gaseous or particle phases each of which has different human health impacts due to their ultimate fate in the body. Here we report on the simultaneous sampling of both phases of airborne PAHs for the first time in underground platinum mines in South Africa, which was made possible by employing small, portable denuder sampling devices consisting of two polydimethylsiloxane (PDMS) multi-channel traps connected in series separated by a quartz fibre filter, which only require small, battery operated portable personal sampling pumps for air sampling. Thermal desorption coupled with comprehensive gas chromatography-mass spectrometry (TD-GC×GC-TofMS) was used to analyse denuder samples taken in three different platinum mines. The samples from a range of underground environments revealed that PAHs were predominantly found in the gas phase with naphthalene and mono-methylated naphthalene derivatives being detected at the highest concentrations ranging from 0.01 to 18 ?g m(-3). The particle bound PAHs were found in the highest concentrations at the idling load haul dump vehicle exhausts with a dominance of fluoranthene and pyrene. Particle associated PAH concentrations ranged from 0.47 to 260 ng m(-3) and included benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene and benzo[ghi]perylene. This work highlights the need to characterise both phases in order to assess occupational exposure to PAHs in this challenging sampling environment. PMID:25582484

  10. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of semivolatile organic compounds in bottom sediment by solvent extraction, gel permeation chromatographic fractionation, and capillary-column gas chromatography/mass spectrometry

    USGS Publications Warehouse

    Furlong, E.T.; Vaught, D.G.; Merten, L.M.; Foreman, W.T.; Gates, P.M.

    1996-01-01

    A method for the determination of 79 semivolatile organic compounds (SOCs) and 4 surrogate compounds in soils and bottom sediment is described. The SOCs are extracted from bottom sediment by solvent extraction, followed by partial isolation using high-performance gel permeation chromatography (GPC). The SOCs then are qualitatively identified and quantitative concentrations determined by capillary-column gas chromatography/mass spectrometry (GC/MS). This method also is designed for an optional simultaneous isolation of polychlorinated biphenyls (PCBs) and organochlorine (OC) insecticides, including toxaphene. When OCs and PCBs are determined, an additional alumina- over-silica column chromatography step follows GPC cleanup, and quantitation is by dual capillary- column gas chromatography with electron-capture detection (GC/ECD). Bottom-sediment samples are centrifuged to remove excess water and extracted overnight with dichloromethane. The extract is concentrated, centrifuged, and then filtered through a 0.2-micrometer polytetrafluoro-ethylene syringe filter. Two aliquots of the sample extract then are quantitatively injected onto two polystyrene- divinylbenzene GPC columns connected in series. The SOCs are eluted with dichloromethane, a fraction containing the SOCs is collected, and some coextracted interferences, including elemental sulfur, are separated and discarded. The SOC-containing GPC fraction then is analyzed by GC/MS. When desired, a second aliquot from GPC is further processed for OCs and PCBs by combined alumina-over-silica column chromatography. The two fractions produced in this cleanup then are analyzed by GC/ECD. This report fully describes and is limited to the determination of SOCs by GC/MS.

  11. Analytical method for the determination of strychnine in tissues by gas chromatography\\/mass spectrometry: two case reports

    Microsoft Academic Search

    E. P. Marques; F. Gil; P. Proença; P. Monsanto; M. F. Oliveira; A. Castanheira; D. N. Vieira

    2000-01-01

    This paper describes an analytical method for strychnine determination in biological samples by gas chromatography\\/mass spectrometry and their application in the investigation of two cases involving strychnine ingestion: A fatal case and a clinical one. The strychnine is isolated from biological samples using a liquid–liquid extraction procedure. The clean-up procedure is performed using an acid solution. Papaverine is used as

  12. Identification of monoacyl- and monoalkylglycerols by gas-liquid chromatography-mass spectrometry using polar siloxane liquid phases

    Microsoft Academic Search

    J. J. Myher; L. Marai; A. Kuksis

    A comparative study was made of the spectra ob- tained after gas-liquid chromatography-mass spectrometry of the trimethylsilyl ethers of 1- and 2-monoacyl- and monoalkyl- glycerols. The glycerol derivatives were resolved on the basis of positional substitution and the degree of unsaturation on Silar- 5CP (a cyanopropylphenylsiloxane) liquid phase, and the peaks were examined in a Varian MAT CH-5 single-focusing mass

  13. Pyrolysis-Gas Chromatography\\/Mass Spectrometry Identifi cation of Distinctive Structures Providing Humic Character to Organic Materials

    Microsoft Academic Search

    Marta Fuentes; Roberto Baigorri; Francisco J. González-Vila; José M. García-Mina

    Flash pyrolysis-gas chromatography\\/mass spectrometry (Py- GC\\/MS) was used to study the structural transformations of humic fractions formed as a result of composting processes of diverse organic materials (solid wastes of wineries, solid olive- mill wastes, domestic wastes, ovine manures plus straw, and mixtures of animal manures). Sodium hydroxide-extracted total humic-like extracts (THE; humic plus fulvic acids) from the composted and

  14. Microstructure characterization of acetylenic polymers by Curie-point pyrolysis\\/capillary gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    Sandrine Duc; Alain Petit

    1997-01-01

    The degradation of homo- and copolymers of 1-hexyne and phenylacetylene synthesized with a Ziegler-Natta initiating system and a metathesis catalyst have been investigated by pyrolysis-gas chromatography\\/mass spectrometry (Py-GC\\/MS) in order to describe the monomer arrangement in the macromolecular chains. The experiments were performed at 500°C using a Curie-point pyrolyzer and the products were separated by means of a capillary column

  15. Preparation and characterization of Melanorrhoea usitata lacquer film based on pyrolysis–gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    Rong Lu; Yukio Kamiya; Tetsuo Miyakoshi

    2007-01-01

    3-(10-Phenyldecyl)catechol was synthesized by the reaction of catechol and 1-phenyl-10-iododecane, followed by de-protection of the hydroxyl groups of catechol; it was then polymerized into synthetic lacquer film by laccase enzyme, and characterized using pyrolysis–gas chromatography\\/mass spectrometry (Py–GC\\/MS) in order to reveal the polymerization mechanism of Melanorrhoea usitata lacquer. The molecular weight and molecular structure information for each peak in the

  16. Characterization of amino acids and proteinaceous materials using online tetramethylammonium hydroxide (TMAH) thermochemolysis and gas chromatography-mass spectrometry technique

    Microsoft Academic Search

    Xu Zang; Johnie C Brown; Jasper D. H van Heemst; Amanda Palumbo; Patrick G Hatcher

    2001-01-01

    An on-line thermochemolysis technique using tetramethylammonium hydroxide (TMAH) for the characterization of amino acids and proteinaceous materials was developed. Amino acids were converted to their corresponding N-and O-methyl derivatives by TMAH in the pyrolysis chamber for 15 s at 300°C prior to separation and detection by gas chromatography-mass spectrometry. Thermochemolysis reactions of TMAH with protein and macromolecular environmental sample were

  17. Characterization of kenaf ( Hibiscus cannabinus) lignin by pyrolysis-gas chromatography-mass spectrometry in the presence of tetramethylammonium hydroxide

    Microsoft Academic Search

    Ken-ichi Kuroda; Akiko Izumi; Bibhuti B Mazumder; Yoshito Ohtani; Kazuhiko Sameshima

    2002-01-01

    Pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) in the presence of tetramethylammonium hydroxide (TMAH) was applied to kenaf (Hibiscus cannabinus) fibers in order to clarify the chemical composition of in situ lignin. The core and bast samples obtained from the middle position of variety Chinpi-3 were pyrolyzed at 500°C for 4 s with TMAH. The core pyrogram revealed peaks retaining the structural attributes

  18. Development and validation of a gas chromatography–mass spectrometry assay for opiates and cocaine in human teeth

    Microsoft Academic Search

    Manuela Pellegrini; Adriana Casá; Emilia Marchei; Roberta Pacifici; Ruth Mayné; Vanessa Barbero; Oscar Garcia-Algar; Simona Pichini

    2006-01-01

    A procedure based on gas chromatography–mass spectrometry (GC–MS) is described for determination of opiates (6-monoacetylmorphine, morphine and codeine) and cocaine and metabolites (cocaine, benzoylecgonine and cocaethylene) in human teeth. After addition of nalorphine as internal standard, pulverized samples were incubated in HCl at 37°C for 18h. Then, after pH adjustment to 6, and the analytes were extracted with two volumes

  19. Use of gas chromatography-mass spectrometry\\/solid phase microextraction for the identification of MVOCs from moldy building materials

    Microsoft Academic Search

    Loay Wady; Annicka Bunte; Christina Pehrson; Lennart Larsson

    2003-01-01

    Gas chromatography-mass spectrometry\\/solid phase microextraction (GC-MS\\/SPME) was applied to identify microbial volatile organic compounds (MVOCs) in water-damaged, mold-infested building materials (gypsum board papers (n=2), mineral wool, and masonite) and in cultivated molds (Aspergillus penicillioides, Stachybotrys chartarum, and Chaetomium globosum). Three SPME fibers (65-?m PDMS-DVB, 75-?m Carboxen-PDMS, and 70-?m Carbowax-stableflex) designed for automated injection were used of which the latter showed

  20. Characterization of humic substances in highly polluted river sediments by pyrolysis methylation–gas chromatography–mass spectrometry

    Microsoft Academic Search

    Laurence Mansuy; Yassine Bourezgui; Evelyne Garnier-Zarli; Emilie Jardé; Véronique Réveillé

    2001-01-01

    Humic substances were extracted from two sediment cores sampled in a river on the outskirts of a large city (Deûle near Lille, France) and in its highly polluted oxbow-lake. Humic acids (HA) were characterized by infrared spectroscopy and in situ pyrolysis\\/methylation–gas chromatography–mass spectrometry. The main results are the substantial aliphaticity of HA in the oxbow-lake at all depths, mainly due

  1. Comparative study of extraction techniques for determination of garlic flavor components by gas chromatography–mass spectrometry

    Microsoft Academic Search

    Sun-Neo Lee; Nam-Sun Kim; Dong-Sun Lee

    2003-01-01

    Several sampling techniques based on steam distillation (SD), simultaneous distillation and solvent extraction (SDE), solid-phase trapping solvent extraction (SPTE), and headspace solid-phase microextraction (HS-SPME) have been compared for the determination of Korean garlic flavor components by gas chromatography–mass spectrometry (GC–MS). Diallyl disulfide (57.88%), allyl sulfide (23.59%), and diallyl trisulfide (11.40%) were found to be the predominant flavor components of garlic

  2. A Low Thermal Mass Fast Gas Chromatograph and its Implementation in Fast Gas Chromatography Mass Spectrometry with Supersonic Molecular Beams

    Microsoft Academic Search

    Alexander B. Fialkov; Mati Moragn; Aviv Amirav

    A new type of low thermal mass (LTM) fast gas chromatograph (GC) was designed and operated in combination with gas chromatography mass spectrometry (GC-MS) with supersonic molecular beams (SMB), including GC-MS-MS with SMB, thereby providing a novel combination with unique capabilities. The LTM fast GC is based on a short capillary column inserted inside a stainless steel tube that is

  3. A dynamic programming approach for the alignment of signal peaks in multiple gas chromatography-mass spectrometry experiments

    Microsoft Academic Search

    Mark D. Robinson; David P. De Souza; Woon Wai Keen; Eleanor C. Saunders; Malcolm J. Mcconville; Terence P. Speed; Vladimir A. Likic

    2007-01-01

    Background: Gas chromatography-mass spectrometry (GC-MS) is a robust platform for the profiling of certain classes of small molecules in biological samples. When multiple samples are profiled, including replicates of the same sample and\\/or different sample states, one needs to account for retention time drifts between experiments. This can be achieved either by the alignment of chromatographic profiles prior to peak

  4. The automation of the acquisition and evaluation of pyrolysis-gas chromatography–mass spectrometry data for paint samples

    Microsoft Academic Search

    D. Thorburn Burns; K. P. Doolan

    2006-01-01

    The evaluation is described of an automated pyrolysis-gas chromatography–mass spectrometry system combined with a software package to convert total ion current chromatograms into forms that resemble a conventional mass spectra called “spectragrams”. The spectragram for a single paint sample can be “closest fit” matched to a previously created paint pyrogram library via pre-determined target compounds in a handling list. Up

  5. Identification and quantification of the indole alkaloid ibogaine in biological samples by gas chromatography-mass spectrometry

    Microsoft Academic Search

    Carol A. Gallagher; Lindsay B. Hough; Sandra M. Keefner; Ahmad Seyed-Mozaffari; Sydney Archer

    1995-01-01

    A sensitive and highly selective analytical chemical method for measuring the indole alkaloid ibogaine in biological samples has been developed. The method utilizes organic extraction, derivatization with trifluoroacetic anhydride, and detection by combined gas chromatography-mass spectrometry. The deuterated analog of ibogaine, O-[Cd3]-ibogaine, was synthesized and used as an internal standard for the method. Standard curves, constructed from variable amounts of

  6. Rapid determination of cyanide in human plasma and urine by gas chromatography–mass spectrometry with two-step derivatization

    Microsoft Academic Search

    Guojie Liu; Junting Liu; Kenji Hara; Yanfang Wang; Yanping Yu; Lina Gao; Ling Li

    2009-01-01

    Cyanide (CN) is a powerful poison and rapidly toxic agent. Because of its wide availability and high toxicity, quantification of CN in blood and urine is frequently required in clinical and forensic practice. We present a sensitive and less time consuming method based on solid-supported liquid–liquid extraction (SLE) and gas chromatography–mass spectrometry (GC–MS) with two-step derivatization for determination of CN

  7. Routine analysis of plasma busulfan by gas chromatography-mass fragmentography.

    PubMed

    Lai, W K; Pang, C P; Law, L K; Wong, R; Li, C K; Yuen, P M

    1998-12-01

    Busulfan (BU) is a widely used alkylating agent for antineoplastic therapy and marrow ablation in preparation for bone marrow transplantation (BMT). High-dose BU often leads to successful preparation and low relapse but is associated with veno-occlusive disease of liver. We established a protocol to determine postdosage plasma BU concentrations by gas chromatography-mass fragmentography in an attempt to relate clinical outcome to plasma BU concentrations. We used nonisotopic pusulfan as the internal standard. After extraction into ethyl acetate, BU and pusulfan were iodinated into 1, 4-diiodobutane and 1,5-diiodopentane, respectively. Gas chromatography-mass spectrometry (GC-MS) analysis was carried out on an Hewlett-Packard (HP) 5890II gas chromatograph with a 30-m 100% methyl silicon narrow bore, fused-silica capillary column interfaced with an HP 5970A mass spectrometer. Helium was the carrier gas. The sample molecules were identified by total ion monitoring and quantified by selective ion monitoring of m/z 183 and 197. The calibration curve was linear to 4 mg/L. The limit of quantification was 0.04 mg/L, and the analytical recovery was approximately 97%. The within-day and between-day imprecision (CV) was <6% and 9%, respectively. In a preliminary study of 12 children, the BU areas under the BU-time curve were 616-949 micromol. min/L after the first dose and 793-1143 micromol. min/L after the fifth dose. We conclude that the GC-MS procedure is suitable for routine analysis of plasma BU. PMID:9836718

  8. Global profiling of ultraviolet-induced metabolic disruption in Melissa officinalis by using gas chromatography-mass spectrometry.

    PubMed

    Kim, Sooah; Yun, Eun Ju; Hossain, Md Aktar; Lee, Hojoung; Kim, Kyoung Heon

    2012-08-01

    Melissa officinalis contains various secondary metabolites that have health benefits. Generally, irradiating plants with ultraviolet (UV)-B induces the accumulation of secondary metabolites in plants. To understand the effect of UV-B irradiation on the metabolism of M. officinalis, metabolomics based on gas chromatography-mass spectrometry (GC-MS) was used in this study. The GC-MS analysis revealed 37 identified metabolites from various chemical classes, including alcohols, amino acids, inorganic acids, organic acids, and sugars. The metabolite profiles of the groups of M. officinalis irradiated with UV-B were separated and differentiated according to their irradiation times (i.e., 0, 1, and 2 h), using principal component analysis (PCA) and hierarchical clustering analysis (HCA), respectively. The PCA score plots of PC1 and PC2 showed that the three groups with different irradiation times followed a certain trajectory with increasing UV-B irradiation. HCA revealed that metabolic patterns differed among the three groups, and the 1 h-irradiated group was more similar to the control group (0 h) than the 2 h-irradiated group. In particular, UV-B irradiation of plants led to a decrease in sugars such as fructose, galactose, sucrose, and trehalose and an increase in metabolites in the tricarboxylic acid cycle, the proline-linked pentose phosphate pathway, and the phenylpropanoid pathway. This study demonstrated that metabolite profiling with GC-MS is useful for gaining a holistic understanding of UV-induced changes in plant metabolism. PMID:22729379

  9. Versatile characterization of glycosylation modification in CTLA4-Ig fusion proteins by liquid chromatography-mass spectrometry.

    PubMed

    Zhu, Lei; Guo, Qingcheng; Guo, Huaizu; Liu, Tao; Zheng, Yingxin; Gu, Peiming; Chen, Xi; Wang, Hao; Hou, Sheng; Guo, Yajun

    2014-01-01

    CTLA4-Ig is a highly glycosylated therapeutic fusion protein that contains multiple N- and O-glycosylation sites. Glycosylation plays a vital role in protein solubility, stability, serum half-life, activity, and immunogenicity. For a CTLA4-Ig biosimilar development program, comparative analytical data, especially the glycosylation data, can influence decisions about the type and amount of animal and clinical data needed to establish biosimilarity. Because of the limited clinical experience with biosimilars before approval, a comprehensive level of knowledge about the biosimilar candidates is needed to achieve subsequent development. Liquid chromatography-mass spectrometry (LC-MS) is a versatile technique for characterizing N- and O-glycosylation modification of recombinant therapeutic proteins, including 3 levels: intact protein analysis, peptide mapping analysis, and released glycans analysis. In this report, an in-depth characterization of glycosylation of a candidate biosimilar was carried out using a systematic approach: N- and O-linked glycans were identified and electron-transfer dissociation was then used to pinpoint the 4 occupied O-glycosylation sites for the first time. As the results show, the approach provides a set of routine tools that combine accurate intact mass measurement, peptide mapping, and released glycan profiling. This approach can be used to comprehensively research a candidate biosimilar Fc-fusion protein and provides a basis for future studies addressing the similarity of CTLA4-Ig biosimilars. PMID:25484062

  10. A liquid chromatography-mass spectrometry-based metabolome database for tomato.

    PubMed

    Moco, Sofia; Bino, Raoul J; Vorst, Oscar; Verhoeven, Harrie A; de Groot, Joost; van Beek, Teris A; Vervoort, Jacques; de Vos, C H Ric

    2006-08-01

    For the description of the metabolome of an organism, the development of common metabolite databases is of utmost importance. Here we present the Metabolome Tomato Database (MoTo DB), a metabolite database dedicated to liquid chromatography-mass spectrometry (LC-MS)- based metabolomics of tomato fruit (Solanum lycopersicum). A reproducible analytical approach consisting of reversed-phase LC coupled to quadrupole time-of-flight MS and photodiode array detection (PDA) was developed for large-scale detection and identification of mainly semipolar metabolites in plants and for the incorporation of the tomato fruit metabolite data into the MoTo DB. Chromatograms were processed using software tools for mass signal extraction and alignment, and intensity-dependent accurate mass calculation. The detected masses were assigned by matching their accurate mass signals with tomato compounds reported in literature and complemented, as much as possible, by PDA and MS/MS information, as well as by using reference compounds. Several novel compounds not previously reported for tomato fruit were identified in this manner and added to the database. The MoTo DB is available at http://appliedbioinformatics.wur.nl and contains all information so far assembled using this LC-PDA-quadrupole time-of-flight MS platform, including retention times, calculated accurate masses, PDA spectra, MS/MS fragments, and literature references. Unbiased metabolic profiling and comparison of peel and flesh tissues from tomato fruits validated the applicability of the MoTo DB, revealing that all flavonoids and alpha-tomatine were specifically present in the peel, while several other alkaloids and some particular phenylpropanoids were mainly present in the flesh tissue. PMID:16896233

  11. Structural investigation of isolated aquatic fulvic and humic acids in seepage water of waste deposits by pyrolysis-gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    Franz-Josef Göbbels; Wilhelm Püttmann

    1997-01-01

    Fulvic and humic acids isolated from seepage waters of four municipal waste landfills and one hazardous waste landfill were analysed by Curie point pyrolysis-gas chromatography\\/mass spectrometry (Py?GCMS). Furthermore, fulvic and humic acids were subjected to acid hydrolysis followed by alkaline hydrolysis. The hydrolysis products were analysed by gas chromatography\\/mass spectrometry (GCMS) and the residues by Py?GCMS. Results show that the

  12. [Development of a gas chromatography-mass spectrometry method for the metabolomic study of rice (Oryza sativa L.) grain].

    PubMed

    Zhou, Jia; Wang, Shuangyuan; Chang, Yuwei; Zhao, Yanni; Lu, Xin; Zhao, Chunxia; Xu, Guowang

    2012-10-01

    An analytical strategy for the metabolic profiling of rice grain was developed based on gas chromatography-mass spectrometry (GC-MS). For the purpose of obtaining abundant metabolite information, sample preparation step prior to instrumental analysis is necessary to be optimized. D-optimal experimental design was applied to optimize the extraction solvent. Four solvents, including water, methanol, isopropanol and acetonitrile, and their combinations were evaluated for the extraction efficiency using multivariate statistical analysis (partial least square regression). The count of resolved peaks and the sum of peak areas were taken as the evaluation indexes. Methanol/water (80:20, v/v) mixture was highly efficient for rice metabolites and was selected as the suitable solvent formulation. Then, the analytical characteristics of the method were measured. More than 90% of the metabolites had satisfactory precisions, reproducibilities and stabilities (relative standard deviations (RSDs) < 30%). Most of the detected metabolites (about 88.0% of total peak area) showed good linear responses. With the optimized analytical protocol, 315 metabolites were detected in rice and 86 of which were structurally identified by searching in the NIST 08/Wiley standard mass spectral library, covering carbohydrates, amino acids, organic acids, steroids and so on which showed a broad coverage of metabolite data. The established method is expected to be useful for the metabolomic studies of rice. PMID:23383493

  13. Headspace single drop microextraction of methylcyclopentadienyl-manganese tricarbonyl from water samples followed by gas chromatography-mass spectrometry.

    PubMed

    Pereira, Francisco Javier Pena; Bendicho, Carlos; Kalogerakis, Nicolas; Psillakis, Elefteria

    2007-11-15

    Headspace single drop microextraction coupled to gas chromatography-mass spectrometry yielded a simple, fast and virtually solventless analytical protocol used for the headspace analysis of aqueous samples contaminated with methylcyclopentadienyl-manganese tricarbonyl (MMT). Initially, several experimental parameters were controlled and optimized and the optimum conditions found were 2.5 microl octane microdrop exposed for 20 min to the headspace of a 10 ml aqueous sample (15 ml vial) containing 20% (w/v) NaCl and stirred at 1250 rpm. The calculated calibration curves gave a high level of linearity for MMT with correlation coefficients >0.9995 after conducting a 3-day study. The limit of detection was calculated to be 0.21 microg l(-1). The proposed method achieved an enrichment factor of the order of 2100 and a 53% recovery after extracting the spiked aqueous solution for 20 min under the optimized experimental conditions. The repeatability and intra-day reproducibility of the proposed method, expressed as relative standard deviation were 8.4 and 6.4%, respectively. Finally, analysis of spiked tap and wastewater samples revealed that matrix had little effect upon extraction. PMID:18371611

  14. MET-COFEA: a liquid chromatography/mass spectrometry data processing platform for metabolite compound feature extraction and annotation.

    PubMed

    Zhang, Wenchao; Chang, Junil; Lei, Zhentian; Huhman, David; Sumner, Lloyd W; Zhao, Patrick X

    2014-07-01

    In this paper, we present a novel liquid chromatography/mass spectrometry (LC/MS) data processing and analysis platform, MET-COFEA (METabolite COmpound Feature Extraction and Annotation). MET-COFEA detects and clusters chromatographic peak features for each metabolite compound by first comprehensively evaluating retention time and peak shape criteria and then annotating the associations between each peak's observed m/z value with the corresponding metabolite compound's molecular mass. MET-COFEA integrates a series of innovative approaches, including novel mass trace based extracted-ion chromatogram (EIC) extraction, continuous wavelet transform (CWT)-based peak detection, and compound-associated peak clustering and peak annotation algorithms. On the basis of the deduced neutral molecular mass and retention time, we have also developed a new alignment algorithm that uses compound-associated peak groups instead of individual peaks to align the same metabolite compound across samples from different electrospray ionization (ESI) modes, different instruments, even different experimental conditions. MET-COFEA has been systematically tested on a series of LC/MS profiles of mixed standards at different concentrations as well as real untargeted LC/MS plant metabolomics data. We compared the performances of MET-COFEA with the existing publicly available tools at LC/MS peak analysis level and demonstrated its excellent performance in this arena. MET-COFEA is freely available at http://bioinfo.noble.org/manuscript-support/met-cofea/. PMID:24856452

  15. Isotope dilution gas chromatography-mass spectrometry in the determination of benzene, toluene, styrene and acrylonitrile in mainstream cigarette smoke.

    PubMed

    Byrd, G D; Fowler, K W; Hicks, R D; Lovette, M E; Borgerding, M F

    1990-03-23

    A cryogenic trapping method with isotope dilution gas chromatography-mass spectrometry analysis has been developed for the determination of benzene, toluene, styrene and acrylonitrile in mainstream vapor phase cigarette smoke. The method is simple, direct, and quantitative. Vapor phase samples are collected cryogenically in a series of four traps following removal of the particulate phase with a Cambridge filter pad. For all four analytes, 75-85% of the total amounts recovered were found in the initial trap and less than 1% in the final trap. Assessment of instrumental precision by multiple injections of a sample gave relative standard deviations of less than 2%. Linear calibration for all analytes over the analysis range gave an r2 value greater than 0.99 with average relative standard deviations at the mean ranging from 1.4 to 8.2%. The cigarettes analyzed include a reference cigarette (Kentucky 1R4F), a commercial ultra-low "tar" mentholated cigarette, and two cigarettes that heat but do not burn tobacco. The values determined for the four analytes in the 1R4F samples are comparable to reported values of similar cigarettes. The cigarettes which heat rather than burn tobacco yield less of all four analytes compared to the other cigarettes in the study. PMID:2185256

  16. Isotope dilution liquid chromatography - mass spectrometry methods for fat- and water-soluble vitamins in nutritional formulations.

    PubMed

    Phinney, Karen W; Rimmer, Catherine A; Thomas, Jeanice Brown; Sander, Lane C; Sharpless, Katherine E; Wise, Stephen A

    2011-01-01

    Vitamins are essential to human health, and dietary supplements containing vitamins are widely used by individuals hoping to ensure they have adequate intake of these important nutrients. Measurement of vitamins in nutritional formulations is necessary to monitor regulatory compliance and in studies examining the nutrient intake of specific populations. Liquid chromatographic methods, primarily with UV absorbance detection, are well established for both fat- and water-soluble measurements, but they do have limitations for certain analytes and may suffer from a lack of specificity in complex matrices. Liquid chromatography-mass spectrometry (LC-MS) provides both sensitivity and specificity for the determination of vitamins in these matrices, and simultaneous analysis of multiple vitamins in a single analysis is often possible. In this work, LC-MS methods were developed for both fat- and water-soluble vitamins and applied to the measurement of these analytes in two NIST Standard Reference Materials. When possible, stable isotope labeled internal standards were employed for quantification. PMID:21117618

  17. Chemical characterization of automotive polyurethane foam using solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Parsons, Norah S; Lam, Michael H W; Hamilton, Sheilah E

    2013-01-01

    Solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was used in this study to identify volatile organic compounds (VOCs) emitted from heated automotive polyurethane (PU) foam collected from 17 different automobiles located in Yuen Long, HK SAR. The samples (0.05 g each) underwent incubation inside 5-mL glass vials for 30 min, and the VOCs were then collected from the headspace with a polydimethylsiloxane fiber by insertion for 30 min. The VOCs were then qualitatively identified by GC-MS analysis and were mostly found to be saturated hydrocarbons. However, differences were noted from car to car in the retention time range of 10-23 min. The VOCs collected during this segment of retention time from the PU foams ranged from antioxidants, food preservatives, pesticides, plasticizers, flame retardants to antiseptic agents. The results obtained from this study therefore highlight the usefulness of SPME/GC-MS as a form of chemical characterization in the analysis of PU foams in forensic casework. PMID:22994148

  18. A gas chromatography-mass spectrometry based study on serum metabolomics in rats chronically poisoned with hydrogen sulfide.

    PubMed

    Deng, Mingjie; Zhang, Meiling; Huang, Xueli; Ma, Jianshe; Hu, Lufeng; Lin, Guanyang; Wang, Xianqin

    2015-05-01

    Hydrogen sulfide poisoning is a common occupational hazard, whose mortality and incidence rates are first and second, respectively, among occupational poisoning incidents in China. The main target organs of its toxicity are in the central nervous system and respiratory system. However, there are currently no specific direct tests that can be used to diagnose poisoned patients. In this study, we developed a serum metabonomic method using orthogonal partial least squares-discriminate analysis (OPLS-DA), based on gas chromatography-mass spectrometry (GC/MS) to evaluate the effect of chronic poisoning by hydrogen sulfide in rats. The OPLS-DA data demonstrated that the model group (n = 60) differed significantly from the control group (n = 30), suggesting that the metabolic profiles of the two groups are markedly different. Alterations in the levels of some metabolites such as citrate, galactose, lactate, mannose, inositol, urea, phosphate, alanine and valine were detected by OPLS-DA analysis. We observed changes in metabolic pathways including lipid metabolism, energy metabolism and amino metabolism in the model group. Our results indicate that GC/MS-based metabonomic methods may provide novel detection means for chronic hydrogen sulfide poisoning. PMID:25882152

  19. Plasma Metabolite Profiling and Chemometric Analyses of Lung Cancer along with Three Controls through Gas Chromatography-Mass Spectrometry

    PubMed Central

    Musharraf, Syed Ghulam; Mazhar, Shumaila; Choudhary, Muhammad Iqbal; Rizi, Nadeem; Atta-ur-Rahman

    2015-01-01

    Lung cancer has been the most common death causing cancer in the world for several decades. This study is focused on the metabolite profiling of plasma from lung cancer (LC) patients with three control groups including healthy non-smoker (NS), smokers (S) and chronic obstructive pulmonary disease patients (COPD) samples using gas chromatography-mass spectrometry (GC-MS) in order to identify the comparative and distinguishing metabolite pattern for lung cancer. Metabolites obtained were identified through National Institute of Standards and Technology (NIST) mass spectral (Wiley registry) and Fiehn Retention Time Lock (RTL) libraries. Mass Profiler Professional (MPP) Software was used for the alignment and for all the statistical analysis. 32 out of 1,877 aligned metabolites were significantly distinguished among three controls and lung cancer using p-value ? 0.001. Partial Least Square Discriminant Analysis (PLSDA) model was generated using statistically significant metabolites which on external validation provide high sensitivity (100%) and specificity (78.6%). Elevated level of fatty acids, glucose and acids were observed in lung cancer in comparison with control groups apparently due to enhanced glycolysis, gluconeogenesis, lipogenesis and acidosis, indicating the metabolic signature for lung cancer. PMID:25712604

  20. 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...

  1. Determination of 3-quinuclidinyl benzilate (QNB) and its major metabolites in urine by isotope dilution gas chromatography/mass spectrometry.

    PubMed

    Byrd, G D; Paule, R C; Sander, L C; Sniegoski, L T; White, E; Bausum, H T

    1992-01-01

    In response to the scheduled destruction of U.S. military stockpiles of the hallucinogenic agent 3-quinuclidinyl benzilate (QNB), a specific confirmatory test for human exposure to QNB was developed. The amount of the parent compound in the urine as well as the two major metabolites, 3-quinuclidinol (Q) and benzilic acid (BA), was determined because the relationship between QNB dose and levels of QNB and its metabolites in human urine is not known. QNB was determined in urine samples spiked at a target level of 0.5 ng/mL, and the metabolites BA and Q were determined at a target level of 5 ng/mL. The method uses solid-phase extraction to isolate each analyte from the urine and isotope dilution gas chromatography/mass spectrometry for quantitation. Each analyte is converted to its trimethylsilyl derivative for analysis. The analytical method was tested on eight different urine samples spiked with known amounts of the analytes near the target levels, at 10 times the target levels, and blank (unspiked) urine samples. The variabilities in the method are for the most part evenly distributed between three imprecision categories: GC/MS measurement, sample preparation, and the urine samples. The total imprecision (1 standard deviation) of a single measurement is about 15% of the value for each analyte. PMID:1522714

  2. Oligosaccharide Substrate Preferences of Human Extracellular Sulfatase Sulf2 Using Liquid Chromatography-Mass Spectrometry Based Glycomics Approaches

    PubMed Central

    Huang, Yu; Mao, Yang; Buczek-Thomas, Jo Ann; Nugent, Matthew A.; Zaia, Joseph

    2014-01-01

    Sulfs are extracellular endosulfatases that selectively remove the 6-O-sulfate groups from cell surface heparan sulfate (HS) chain. By altering the sulfation at these particular sites, Sulfs function to remodel HS chains. As a result of the remodeling activity, HSulf2 regulates a multitude of cell-signaling events that depend on interactions between proteins and HS. Previous efforts to characterize the substrate specificity of human Sulfs (HSulfs) focused on the analysis of HS disaccharides and synthetic repeating units. In this study, we characterized the substrate preferences of human HSulf2 using HS oligosaccharides with various lengths and sulfation degrees from several naturally occurring HS sources by applying liquid chromatography mass spectrometry based glycomics methods. The results showed that HSulf2 preferentially digests highly sulfated HS oligosaccharides with zero acetyl groups and this preference is length dependent. In terms of length of oligosaccharides, HSulf2 digestion induced more sulfation decrease on DP6 (DP: degree of polymerization) compared to DP2, DP4 and DP8. In addition, the HSulf2 preferentially digests the oligosaccharide domain located at the non-reducing end (NRE) of the HS and heparin chain. In addition, the HSulf2 digestion products were altered only for specific isomers. HSulf2 treated NRE oligosaccharides also showed greater decrease in cell proliferation than those from internal domains of the HS chain. After further chromatographic separation, we identified the three most preferred unsaturated hexasaccharide for HSulf2. PMID:25127119

  3. Characterization of important odorants in steamed male Chinese mitten crab (Eriocheir sinensis) using gas chromatography-mass spectrometry-olfactometry.

    PubMed

    Wu, Na; Gu, Saiqi; Tao, Ningping; Wang, Xichang; Ji, Siru

    2014-07-01

    Chinese mitten crab (Eriocheir sinensis) from Yangcheng Lake in Jiangsu Province is a popular species due to its unique pleasant aroma and intensive umami taste. In this study, odorants in steamed male E. sinensis were investigated using the headspace-monolithic material sorptive extraction technique coupled with gas chromatography-mass spectrometry-olfactometry (GC-MS-O). A total of 74 volatile compounds were found, and the results of the GC-MS-O analysis, combined with odor activity values, showed that trimethylamine (fishy, ammonia-like odor), (Z)-4-heptenal (mushroom-like odor), and benzaldehyde (paint-like odor) were the important odorants (IOs) in all 4 of the edible parts of steamed male E. sinensis. Furthermore, heptanal (mushroom-like odor) was common to the abdomen, claw, and leg meat but was not found as the IO in the gonad. The abdomen meat also contained 3-methylbutanal (vegetable-like, grassy odor), while 2 additional IOs were found in claw meat (2-methylbutanal, which has a mushroom odor and 3-ethyl-2,5-dimethylpyrazine, which has a chocolate-like, musty odor). Another IO (2-nonanone, chocolate-like odor) was also found in leg meat, while (E)-2-nonenal (green, fruity odor) was the IO found exclusively in the gonad. PMID:24962135

  4. [Determination of monoethylglycinexylidide concentration in serum using solid phase extraction and capillary gas chromatography-mass spectrometry].

    PubMed

    Wang, Zhenxia; Zhang, Ruiming; Cao, Wei; Ouyang, Xiaohui; Zhao, Haiping; Dong, Peide; Meng, Xingkai

    2008-05-01

    A novel method for the determination of monoethylglycinexylidide (MEGX) (lidocaine metabolin) in serum using solid phase extraction (SPE) and capillary gas chromatography-mass spectrometry (GC-MS) was established. The serum sample was extracted with a CN-SPE column. An HP-5MS capillary column (15 m x 0.25 mm x 0.1 microm) was used. The initial temperature of the column was set at 100 degrees C, held for 1 min, then raised to 200 degrees C at 40 degrees C/min, and held at 200 degrees C for 0.5 min. The sample size was 2 microL, and the split ratio was set at 1 : 1. The carrier gas was high purity helium with a flow rate of 1.0 mL/min. The monitoring ions for the determination were m/z 58 for MEGX and m/z 86 for procaine (internal standard). The calibration curve of MEGX had good linear relationship in the range of 1.562 - 25 ng/mL ( r = 0.998 1). The limit of detection was 0.5 ng/mL. The extraction recovery ranged from 80.1% to 85.7%. The method advanced the quantitative analysis of MEGX in serum by combining rapid and efficient SPE with specific and sensitive quantitation by GC-MS. PMID:18724665

  5. Novel algorithm for simultaneous component detection and pseudo-molecular ion characterization in liquid chromatography-mass spectrometry.

    PubMed

    Zhang, Yufeng; Wang, Xiaoan; Wo, Siukwan; Ho, Hingman; Han, Quanbin; Fan, Xiaohui; Zuo, Zhong

    2015-01-01

    Resolving components and determining their pseudo-molecular ions (PMIs) are crucial steps in identifying complex herbal mixtures by liquid chromatography-mass spectrometry. To tackle such labor-intensive steps, we present here a novel algorithm for simultaneous detection of components and their PMIs. Our method consists of three steps: (1) obtaining a simplified dataset containing only mono-isotopic masses by removal of background noise and isotopic cluster ions based on the isotopic distribution model derived from all the reported natural compounds in dictionary of natural products; (2) stepwise resolving and removing all features of the highest abundant component from current simplified dataset and calculating PMI of each component according to an adduct-ion model, in which all non-fragment ions in a mass spectrum are considered as PMI plus one or several neutral species; (3) visual classification of detected components by principal component analysis (PCA) to exclude possible non-natural compounds (such as pharmaceutical excipients). This algorithm has been successfully applied to a standard mixture and three herbal extract/preparations. It indicated that our algorithm could detect components' features as a whole and report their PMI with an accuracy of more than 98%. Furthermore, components originated from excipients/contaminants could be easily separated from those natural components in the bi-plots of PCA. PMID:25467485

  6. [Characterization of C5-C7 alkenes in gasoline from methanol to olefins process using gas chromatography-mass spectrometry].

    PubMed

    Li, Jiwen; Li, Wei; Wang, Chuan

    2013-11-01

    Gas chromatography-mass spectrometry (GC-MS) qualitative characterization of C5 -C7 alkenes in gasoline from methanol to olefins (MTO) was investigated in detail. It showed that the retention indices of 49 alkenes, 11 alkadienes and 9 cycloalkenes, a total of 69 C5-C7 isomeric alkenes were determined and qualitatively confirmed. The retention indices of all C5-C7 alkenes in MTO gasoline were measured on polydimethylsiloxane as the stationary phase. According to the library of retention indices by GC-MS characterization, the contents of C5-C7 alkenes in MTO gasoline were analyzed by GC and characterized by its composition of hydrocarbon categories. The results of quantitative analysis showed that the composition of MTO gasoline mainly consisted of C5-C7 alkenes, and a small amount of alkadienes and cycloalkenes. The contents of alkanes and cycloalkanes existed in MTO gasoline were very low. The study of the composition is helpful for the comprehensive application of MTO gasoline. PMID:24558852

  7. [Determination of short chain chlorinated paraffins in leather products by solid phase extraction coupled with gas chromatography-mass spectrometry].

    PubMed

    Zhang, Weiya; Wan, Xin; Li, Lixia; Wang, Chengyun; Jin, Shupei; Xing, Jun

    2014-10-01

    The short chain chlorinated paraffins (SCCPs) are the additives frequently used in the leather production in China, but they have been put into the list of forbidden chemicals issued by European Union recently. In fact, there is not a commonly recognized method for the determination of the SCCPs in the leather products due to the serious matrix interferences from the leather products and the complex chemical structures of the SCCPs. A method of solid phase extraction coupled with gas chromatography-mass spectrometry (SPE-GC-MS) was established for the determination of the SCCPs in the leather products after the optimization of the SPE conditions. It was found that the interferences from the leather products were thor- oughly separated from the analyte of the SCCPs on a home-made solid phase extraction (SPE) column filled with silica packing while eluted with a mixed solvent of n-hexane-methylene chloride (2:1, v/v). With this method, the recoveries for the SCCPs spiked in the real leather samples varied from 90.47% to 99.00% with the relative standard deviations (RSDs) less than 6.7%, and the limits of detection (LODs) were between 0.069 and 0.110 mg/kg. This method is suitable for qualitative and quantitative analysis of SCCPs in the leather products. PMID:25739278

  8. Metal free columns for determination of deoxynucleotide monophosphate by liquid chromatography/mass spectrometry and application to oligonucleotide.

    PubMed

    Shibayama, Sachie; Sakamaki, Hiroshi; Yamazaki, Taichi; Takatsu, Akiko

    2015-08-01

    We have developed a highly sensitive method for the analysis of deoxynucleotide monophosphates (dNMPs), which involves the use of liquid chromatography/mass spectrometry (LC/MS) and a new metal-free column. The new column solves the problem that the phosphate group in dNMPs interacts with the metal portion of the device or column. After optimization of the analytical conditions, the limits of detection (LODs) of dNMPs were from 5.4ng/g to 6.3ng/g. Those values were 10 times lower than the LODs of previous methods. We applied the method to the determination of the base composition and the quantification of 20-mer oligonucleotide. Despite use of a very small sample amount of 14.5ng, we were able to determine the base composition, and the result was consistent with theoretical values. We were also able to quantify the mass fraction of oligonucleotide with 8.2% expanded uncertainty (k=2). By means of the developed method, we were able to analyze dNMPs with high sensitivity as well as determine the base composition and quantify the mass fraction of oligonucleotide despite use of a small amount of sample. PMID:26141274

  9. MSPD procedure for determining buprofezin, tetradifon, vinclozolin, and bifenthrin residues in propolis by gas chromatography-mass spectrometry.

    PubMed

    dos Santos, Thaíse Fernanda Santana; Aquino, Adriano; Dórea, Haroldo Silveira; Navickiene, Sandro

    2008-03-01

    A simple and effective extraction method based on matrix solid-phase dispersion (MSPD) was developed to determine bifenthrin, buprofezin, tetradifon, and vinclozolin in propolis using gas chromatography-mass spectrometry in selected ion monitoring mode (GC-MS, SIM). Different method conditions were evaluated, for example type of solid phase (C(18), alumina, silica, and Florisil), the amount of solid phase and eluent (n-hexane, dichloromethane, dichloromethane-n-hexane (8:2 and 1:1, v/v) and dichloromethane-ethyl acetate (9:1, 8:2 and 7:3, v/v)). The best results were obtained using 0.5 g propolis, 1.0 g silica as dispersant sorbent, 1.0 g Florisil as clean-up sorbent, and dichloromethane-ethyl acetate (9:1, v/v) as eluting solvent. The method was validated by analysis of propolis samples fortified at different concentration levels (0.25 to 1.0 mg kg(-1)). Average recoveries (four replicates) ranged from 67% to 175% with relative standard deviation between 5.6% and 12.1%. Detection and quantification limits ranged from 0.05 to 0.10 mg kg(-1) and 0.15 to 0.25 mg kg(-1) propolis, respectively. PMID:18193409

  10. Characterization of tetramethylammonium hydroxide thermochemolysis products of near-shore marine sediments using gas chromatography\\/mass spectrometry and gas chromatography\\/combustion\\/isotope ratio mass spectrometry

    Microsoft Academic Search

    Jerry Pulchan; Teofilo A. Abrajano; Robert Helleur

    1997-01-01

    The study describes the application of gas chromatography\\/mass spectrometry (GC\\/MS) and gas chromatography\\/combustion\\/isotope ratio mass spectrometry (GC\\/C\\/IRMS) to characterize the molecular and compound-specific stable carbon isotope composition, respectively, of tetramethylammonium hydroxide (TMAH) thermochemolysis products of organic matter present in marine sediments. The objective of the study was to examine the usefulness of TMAH thermochemolysis products in identifying organic markers of

  11. Detecting Organic Compounds in Martian Soil Analogues Using Gas Chromatography Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Glavin, D. P.; Buch, A.; Mahaffy, P. R.

    2004-01-01

    One of the primary objectives of the 1976 Viking missions was to determine whether organic compounds, possibly of biological origin, were present in the Martian surface soils. The Viking gas chromatography mass spectrometry (GCMS) instruments found no evidence for any organic compounds of Martian origin above a few parts per billion in the upper 10 cm of surface soil [l], suggesting the absence of a widely distributed Martian biota. However, Benner et d. have suggested that significant amounts of non-volatile organic compounds, possibly including oxidation products of bioorganic molecules (e.g. carboxylic acids) would not have been detected by the Viking GCMS [2]. Moreover, other key organic compounds important to biology, such as amino acids and nucleobases, would also likely have been missed by the Viking GCMS as these compounds require chemical derivatization to be stable in a GC column [3]. Recent pyrolysis experiments with a Mars soil analogue that had been innoculated with Escherichia coli bacteria have shown that amino acid decomposition products (amines) and nucleobases are among the most abundant products generated after pyrolysis of the bacterial cells [4,5]. At the part per billion level (Viking GCMS detection limit), these pyrolysis products generated from several million bacterial cells per gram of Martian soil would not have been detected by the Viking GCMS instruments [4]. Analytical protocols are under development for upcoming in situ lander opportunities to target several important biological compounds including amino acids and nucleobases. For example, extraction and chemical derivatization techniques [3] are being adapted for space flight use to transform reactive or fragile molecules that would not have been detected by the Viking GCMS instruments, into species that are sufficiently volatile to be detected by GCMS. Recent experiments carried out at NASA Goddard have shown that using this derivatization technique all of the targeted compounds mentioned above can be separated on a GC column and detected by MS at sub-picomole (< 10(exp -l2 mole) levels. With these methods, the detection limit for amino acids, carboxylic acids and nucleobases is several orders of magnitude more sensitive than the Viking GCMS instruments for these compounds. Preliminary results using this analytical technique on a variety of Martian soil analogues will be presented.

  12. Characterization of livestock odors using steel plates, solid-phase microextraction, and multidimensional gas chromatography-mass spectrometry-olfactometry.

    PubMed

    Bulliner, Edward A; Koziel, Jacek A; Cai, Lingshuang; Wright, Donald

    2006-10-01

    Livestock operations are associated with emissions of odor, gases, and particulate matter (PM). Livestock odor characterization is one of the most challenging analytical tasks. This is because odor-causing gases are often present at very low concentrations in a complex matrix of less important or irrelevant gases. The objective of this project was to develop a set of characteristic reference odors from a swine barn in Iowa and, in the process, identify compounds causing characteristic swine odor. Odor samples were collected using a novel sampling methodology consisting of clean steel plates exposed inside and around the swine barn for < or =1 week. Steel plates were then transported to the laboratory and stored in clean jars. Headspace solid-phase microextraction was used to extract characteristic odorants collected on the plates. All of the analyses were conducted on a gas chromatography-mass spectrometry-olfactometry system where the human nose is used as a detector simultaneously with chemical analysis via mass spectrometry. Multidimensional chromatography was used to isolate and identify chemicals with high-characteristic swine odor. The effects of sampling time, distance from a source, and the presence of PM on the abundance of specific gases, odor intensity, and odor character were tested. Steel plates were effectively able to collect key volatile compounds and odorants. The abundance of specific gases and odor was amplified when plates collected PM. The results of this research indicate that PM is major carrier of odor and several key swine odorants. Three odor panelists were consistent in identifying p-cresol as closely resembling characteristic swine odor, as well as attributing to p-cresol the largest odor response out of the samples. Further research is warranted to determine how the control of PM emissions from swine housing could affect odor emissions. PMID:17063862

  13. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of 86 volatile organic compounds in water by gas chromatography/mass spectrometry, including detections less than reporting limits

    USGS Publications Warehouse

    Connor, Brooke F.; Rose, Donna L.; Noriega, Mary C.; Murtaugh, Lucinda K.; Abney, Sonja R.

    1998-01-01

    This report presents precision and accuracy data for volatile organic compounds (VOCs) in the nanogram-per-liter range, including aromatic hydrocarbons, reformulated fuel components, and halogenated hydrocarbons using purge and trap capillary-column gas chromatography/mass spectrometry. One-hundred-four VOCs were initially tested. Of these, 86 are suitable for determination by this method. Selected data are provided for the 18 VOCs that were not included. This method also allows for the reporting of semiquantitative results for tentatively identified VOCs not included in the list of method compounds. Method detection limits, method performance data, preservation study results, and blank results are presented. The authors describe a procedure for reporting low-concentration detections at less than the reporting limit. The nondetection value (NDV) is introduced as a statistically defined reporting limit designed to limit false positives and false negatives to less than 1 percent. Nondetections of method compounds are reported as ?less than NDV.? Positive detections measured at less than NDV are reported as estimated concentrations to alert the data user to decreased confidence in accurate quantitation. Instructions are provided for analysts to report data at less than the reporting limits. This method can support the use of either method reporting limits that censor detections at lower concentrations or the use of NDVs as reporting limits. The data-reporting strategy for providing analytical results at less than the reporting limit is a result of the increased need to identify the presence or absence of environmental contaminants in water samples at increasingly lower concentrations. Long-term method detection limits (LTMDLs) for 86 selected compounds range from 0.013 to 2.452 micrograms per liter (?g/L) and differ from standard method detection limits (MDLs) in that the LTMDLs include the long-term variance of multiple instruments, multiple operators, and multiple calibrations over a longer time. For these reasons, LTMDLs are expected to be slightly higher than standard MDLs. Recoveries for all of the VOCs tested ranged from 36 (tert-butyl formate) to 155 percent (pentachlorobenzene). The majority of the compounds ranged from 85 to 115 percent recovery and had less than 5 percent relative standard deviation for concentrations spiked between 1 to 500 ?g/L in volatile blank-, surface-, and ground-water samples. Recoveries of 60 set spikes at low concentrations ranged from 70 to 114 percent (1,2,3- trimethylbenzene and acetone). Recovery data were collected over 6 months with multiple instruments, operators, and calibrations. In this method, volatile organic compounds are extracted from a water sample by actively purging with helium. The VOCs are collected onto a sorbent trap, thermally desorbed, separated by a Megabore gas chromatographic capillary column, and finally determined by a full-scan quadrupole mass spectrometer. Compound identification is confirmed by the gas chromatographic retention time and by the resultant mass spectrum, typically identified by three unique ions. An unknown compound detected in a sample can be tentatively identified by comparing the unknown mass spectrum to reference spectra in the mass-spectra computer-data system library compiled by the National Institute of Standards and Technology.

  14. A simple and reliable procedure for the determination of psychoactive drugs in oral fluid by gas chromatography–mass spectrometry

    Microsoft Academic Search

    Mitona Pujadas; Simona Pichini; Ester Civit; Elena Santamariña; Katherine Perez; Rafael de la Torre

    2007-01-01

    A simple and reliable gas chromatography–mass spectrometry method for identifying and quantifying psychoactive drugs in oral fluid is described. Substances under investigation were: psychostimulant drugs (amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine, 3,4-methylenedioxiamphetamine, 3,4-methylenedioxy-N-ethylamphetamine, phentermine), cocaine and metabolites (benzoylecgonine, cocaethylene, and ecgonine methyl esther), cannabinoids (delta-9-tetrahydrocannabinol, 11-nor-9-carboxy-delta-9-tetrahydrocannabinol, 11-hydroxy-delta-9-tetrahydrocannabinol, cannabinol and cannabidiol), opiates (6-monoacetylmorphine, morphine and codeine), hypnotics (flurazepam, flunitrazepam, dipotassium chlorazepate, alprazolam, diazepam and

  15. Liquid chromatography-mass spectrometry method for determination of ramipril and its active metabolite ramiprilat in human plasma.

    PubMed

    Zhu, Zhimeng; Vachareau, Andre; Neirinck, Len

    2002-11-01

    A fast and robust liquid chromatography-mass spectrometry (LC-MS-MS) method has been developed for simultaneous quantitation of the angiotensin-converting enzyme (ACE) inhibitor, ramipril and its metabolite ramiprilat in human plasma. The method involves a solid-phase extraction from plasma, simple isocratic chromatography conditions and mass spectrometric detection that enables a detection limit at sub-nanogram levels. The proposed method has been validated with a linear range of 0.5-250 ng/ml for both ramipril and ramiprilat. The overall recoveries for ramipril and ramiprilat were 88.7 and 101.8%, respectively. PMID:12361743

  16. Simultaneous Determination of Nalbuphine and Opiates in Human Hair by Gas Chromatography-Mass Spectrometry

    Microsoft Academic Search

    Jin Young Kim; Moon Kyo In; Ki-Jung Paeng; Bong Chul Chung

    2004-01-01

    The method for simultaneous determination of nalbuphine and opiates (codeine, morphine, and 6-monoacetylmorphine) in human hair was developed in the selected-ion monitoring (SIM) mode of a gas chromatography-mass spectrometer (GC-MS). Thirty-milligram hair samples were incubated in 0.01 M HCl overnight at 50 °C. We extracted the drugs from resulting hydrolyzed solutions with a mixture of chloroform-isopropanol- n-heptane (50:17:33, v\\/ v\\/

  17. Combined solid-phase extraction and gas chromatography-mass spectrometry used for determination of chloropropanols in water.

    PubMed

    González, Paula; Racamonde, Inés; Carro, Antonia M; Lorenzo, Rosa A

    2011-10-01

    A sensitive and rapid derivatization method for the simultaneous determination of 1,3-dichloro-2-propanol (1,3-DCP) and 3-chloropropane-1,2-diol (3-MCPD) in water samples has been developed. The aim was to research the optimal conditions of the derivatization process for two selected reagents. A central composite design was used to determine the influence of derivatization time, derivatization temperature and reagent volume. A global desirability function was applied for multi-response optimization. The analysis was performed by gas chromatography-mass spectrometry. During the optimization of the extraction procedure, four different types of solid-phase extraction (SPE) columns were tested. It was demonstrated that the Oasis HLB cartridge produced the best recoveries of the target analytes. The pH value and the salinity were investigated using a Doehlert design. The best results for the SPE of both analytes were obtained with 1.5 g of NaCl and pH 6. The proposed method provides high sensitivity, good linearity (R(2)?0.999) and repeatability (relative standard deviations % between 2.9 and 3.4%). Limits of detection and quantification were in the range of 1.4-11.2 ng/mL and 4.8-34.5 ng/mL, respectively. Recoveries obtained for water samples were ca. 100% for 1,3-DCP and 3-MCPD. The method has been successfully applied to the analysis of different samples including commercially bottled water, an influent and effluent sewage. PMID:21818849

  18. Hydrophilic interaction chromatography-mass spectrometry for anionic metabolic profiling of urine from antibiotic-treated rats.

    PubMed

    Kok, Miranda G M; Swann, Jonathan R; Wilson, Ian D; Somsen, Govert W; de Jong, Gerhardus J

    2014-04-01

    Hydrophilic interaction chromatography-mass spectrometry (HILIC-MS) was used for anionic metabolic profiling of urine from antibiotic-treated rats to study microbial-host co-metabolism. Rats were treated with the antibiotics penicillin G and streptomycin sulfate for four or eight days and compared to a control group. Urine samples were collected at day zero, four and eight, and analyzed by HILIC-MS. Multivariate data analysis was applied to the urinary metabolic profiles to identify biochemical variation between the treatment groups. Principal component analysis found a clear distinction between those animals receiving antibiotics and the control animals, with twenty-nine discriminatory compounds of which twenty were down-regulated and nine up-regulated upon treatment. In the treatment group receiving antibiotics for four days, a recovery effect was observed for seven compounds after cessation of antibiotic administration. Thirteen discriminatory compounds could be putatively identified based on their accurate mass, including aconitic acid, benzenediol sulfate, ferulic acid sulfate, hippuric acid, indoxyl sulfate, penicillin G, phenol and vanillin 4-sulfate. The rat urine samples had previously been analyzed by capillary electrophoresis (CE) with MS detection and proton nuclear magnetic resonance ((1)H NMR) spectroscopy. Using CE-MS and (1)H NMR spectroscopy seventeen and twenty-five discriminatory compounds were found, respectively. Both hippuric acid and indoxyl sulfate were detected across all three platforms. Additionally, eight compounds were observed with both HILIC-MS and CE-MS. Overall, HILIC-MS appears to be highly complementary to CE-MS and (1)H NMR spectroscopy, identifying additional compounds that discriminate the urine samples from antibiotic-treated and control rats. PMID:24503197

  19. A liquid chromatography-mass spectrometry assay for analyzing sulfonamide antibacterials in cattle and fish muscle tissues.

    PubMed

    Bogialli, Sara; Curini, Roberta; Di Corcia, Antonio; Nazzari, Manuela; Samperi, Roberto

    2003-04-15

    A simple and rapid method able to determine residues of 12 sulfonamide (SAs) antibacterials in cattle and trout muscle tissues is presented. This method is based on the matrix solid-phase dispersion technique with hot water as extractant followed by liquid chromatography-mass spectrometry (LC-MS). The LC-MS instrumentation was equipped with an electrospray source and a single quadrupole. After 0.8 g of a flesh sample containing the analytes is deposited on sand (crystobalite), this material is packed into an extraction cell. SAs are extracted by flowing 4 mL of water through the cell heated at 80 degrees C. A 0.5-mL aliquot of the bovine tissue extract is then directly injected into the LC column, while the fish tissue extract is filtered prior to LC-MS analysis. MS data acquisition was performed in the positive-ion mode and monitoring at least three ions for each target compound. Confirmatory ions were produced by the in-source collision-induced dissociation process. At the tolerance levels issued by the EU and U.S. Food and Drug Administration, i.e., 100 ppb, recovery of the analytes in bovine and trout muscle tissues was 75-98% with RSDs ranging between 1 and 8%. Estimated limits of quantification (S/N = 10) were 6-15 ppb for SAs in bovine muscle tissue and 3-13 ppb in trout fillet. When trying to reduce the analysis time by using a short chromatographic run time, severe ion signal suppression was experienced for the early-eluted SAs. This effect was traced to competition effects by polar endogenous coextractives, maybe proteinaceous species, which are eluted in the first part of the chromatographic run. This unwelcome effect was removed by simply adopting more selective chromatographic conditions. PMID:12713036

  20. Measurement of very low stable isotope enrichments by gas chromatography/mass spectrometry: application to measurement of muscle protein synthesis.

    PubMed

    Patterson, B W; Zhang, X J; Chen, Y; Klein, S; Wolfe, R R

    1997-08-01

    Measurement of muscle protein synthesis using stable isotopically labeled tracers usually requires isotope ratio mass spectrometry (IRMS) because of the need to measure very low enrichments of stable isotopically labeled tracers (tracer to tracee ratio [TTR], 0.005% to 0.10%). This approach is laborious, requiring purification of the metabolite of interest and combustion to a gas for IRMS analysis, and is best suited for use with 13C tracers. We have developed an approach whereby low enrichments can be conveniently measured by a conventional gas chromatography/mass spectrometry (GC/MS) instrument. The approach includes three critical elements: (1) use of a highly substituted tracer containing three or more labeled atoms, to measure enrichment above a very low natural abundance of highly substituted isotopomers; (2) use of a highly substituted natural abundance isotopomer as a base ion for comparison rather than the most abundant m + 0 isotopomer, to reduce the dynamic range of the isotopomer ratio measurement; and (3) a sensitive mass spectrometric analysis that measures the natural abundance of the isotopomer used as a tracer with a high signal to noise ratio (> 100:1). This approach was used to measure the rate of synthesis of muscle protein following a primed continuous infusion of L-[13C6]-phenylalanine (PHE) in eight fasted dogs and L-[2H3]-leucine in five fasted human subjects. Values for [13C6]-PHE enrichment by GC/MS rates were virtually identical to those obtained by a conventional approach using high-performance liquid chromatography (HPLC) to isolate PHE, combustion to CO2, and measurement of 13CO2 enrichment by IRMS (IRMS enrichment = 0.9988 x GC/MS enrichment, R2 = .891), resulting in identical values for muscle fractional synthesis rates ([FSRs] mean +/- SEM: 2.7 +/- 0.2 and 2.5 +/- 0.2%/d for GC/MS and IRMS, respectively). Human muscle synthesis rates measured by GC/MS analysis of [2H3]-leucine enrichment (1.90 +/- 0.17%/d) were similar to published values based on IRMS analysis using a 1- 13C-leucine tracer. We conclude that compared with the IRMS approach, the GC/MS approach offers faster throughput, has a lower sample requirement, and is suitable for a wider variety of tracers such as 2H. The principles outlined here should be applicable to the measurement of low enrichments by GC/MS in a wide variety of stable isotope tracer applications. PMID:9258279

  1. Determination of nitrogen mustard hydrolysis products, ethanolamines by gas chromatography-mass spectrometry after tert-butyldimethylsilyl derivatization.

    PubMed

    Ohsawa, Isaac; Seto, Yasuo

    2006-07-28

    A method for determining N-ethyldiethanolamine (EDEA), N-methyldiethanolamine (MDEA) and triethanolamine (TEA), hydrolysis products of nitrogen mustards, in water, urine and blood samples using gas chromatography-mass spectrometry (GC-MS) after derivatization by tert-butyldimethylsilylation (TBDMS) is described. The sample solution was evaporated to dryness, and reacted with N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) at 60 degrees C for 1h. The TBDMS derivatives were separated on a DB-5 column and detected by electron-ionization MS. The quantitation of EDEA, MDEA and TEA was performed by measuring the respective peak areas on the extracted ion chromatograms of m/z 216, m/z 202 and m/z 346, respectively, using nonadecane (C19), the peak area of which was measured at m/z 268, as an internal standard. When the water sample was initially analyzed, considerable loss of EDEA, MDEA and TEA occurred by evaporation. The addition of hydrochloric acid (HCl) to the water sample (final 1 mM), however, permitted quantitative recoveries to be achieved (88%, 88% and 79% for EDEA-(TBDMS)2, MDEA-(TBDMS)2 and TEA-(TBDMS)3, respectively). The limits of detections (LODs, scan mode, S/N = 3) were 2.5, 2.5 and 10 ng/ml for EDEA, MDEA and TEA, respectively. Ethanolamines could be also determined in urine samples (volume 0.1 ml), with reasonable recoveries of 72-100% by the addition of HCl (final 1 mM). For the analysis of serum samples, the sample was precipitated by the addition of perchloric acid (final 3.2%), and the resulting supernatant was neutralized with potassium carbonate, and then acidified by the addition of HCl. The recovery of TBDMS derivatives of ethanolamines was found to rather low (7-31%). PMID:16707130

  2. Full evaporation dynamic headspace and gas chromatography-mass spectrometry for uniform enrichment of odor compounds in aqueous samples.

    PubMed

    Ochiai, Nobuo; Sasamoto, Kikuo; Hoffmann, Andreas; Okanoya, Kazunori

    2012-06-01

    A method for analysis of a wide range of odor compounds in aqueous samples at sub-ng mL?¹ to ?g mL?¹ levels was developed by full evaporation dynamic headspace (FEDHS) and gas chromatography-mass spectrometry (GC-MS). Compared to conventional DHS and headspace solid phase microextraction (HS-SPME), FEDHS provides more uniform enrichment over the entire polarity range for odor compounds in aqueous samples. FEDHS at 80°C using 3 L of purge gas allows complete vaporization of 100 ?L of an aqueous sample, and trapping and drying it in an adsorbent packed tube, while providing high recoveries (85-103%) of the 18 model odor compounds (water solubility at 25°C: log0.54-5.65 mg L?¹, vapor pressure at 25°C: 0.011-3.2 mm Hg) and leaving most of the low volatile matrix behind. The FEDHS-GC-MS method showed good linearity (r²>0.9909) and high sensitivity (limit of detection: 0.21-5.2 ng mL?¹) for the model compounds even with the scan mode in the conventional MS. The feasibility and benefit of the method was demonstrated with analyses of key odor compounds including hydrophilic and less volatile characteristics in beverages (whiskey and green tea). In a single malt whiskey sample, phenolic compounds including vanillin could be determined in the range of 0.92-5.1 ?g mL?¹ (RSD<7.4%, n=6). For a Japanese green tea sample, 48 compounds including 19 potent odorants were positively identified from only 100 ?L of sample. Heat-induced artifact formation for potent odorants was also examined and the proposed method does not affect the additional formation of thermally generated compounds. Eighteen compounds including 12 potent odorants (e.g. coumarin, furaneol, indole, maltol, and pyrazine congeners) were determined in the range of 0.21-110 ng mL?¹ (RSD<10%, n=6). PMID:22542289

  3. Determination of alkylamines in atmospheric aerosol particles: a comparison of gas chromatography-mass spectrometry and ion chromatography approaches

    NASA Astrophysics Data System (ADS)

    Huang, R.-J.; Li, W.-B.; Wang, Y.-R.; Wang, Q. Y.; Jia, W. T.; Ho, K.-F.; Cao, J. J.; Wang, G. H.; Chen, X.; Haddad, I. EI; Zhuang, Z. X.; Wang, X. R.; Prévôt, A. S. H.; O'Dowd, C. D.; Hoffmann, T.

    2014-07-01

    In recent years low molecular weight alkylamines have been recognized to play an important role in particle formation and growth in the lower atmosphere. However, major uncertainties are associated with their atmospheric processes, sources and sinks, mostly due to the lack of ambient measurements and the difficulties in accurate quantification of alkylamines at trace level. In this study, we present the evaluation and optimization of two analytical approaches, i.e., gas chromatography-mass spectrometry (GC-MS) and ion chromatography (IC), for the determination of alkylamines in aerosol particles. Alkylamines were converted to carbamates through derivatization with isobutyl chloroformate for GC-MS determination. A set of parameters affecting the analytical performances of the GC-MS approach, including reagent amount, reaction time and pH value, was evaluated and optimized. The accuracy is 84.3-99.1%, and the limits of detection obtained are 1.8-3.9 pg (or 0.02-0.04 ng m-3). For the IC approach, a solid-phase extraction (SPE) column was used to separate alkylamines from interfering cations before IC analysis. 1-2% (v/v) of acetone (or 2-4% (v/v) of acetonitrile) was added to the eluent to improve the separation of alkylamines on the IC column. The limits of detection obtained are 2.1-15.9 ng (or 0.9-6.4 ng m-3), and the accuracy is 55.1-103.4%. The lower accuracy can be attributed to evaporation losses of amines during the sample concentration procedure. Measurements of ambient aerosol particle samples collected in Hong Kong show that the GC-MS approach is superior to the IC approach for the quantification of primary and secondary alkylamines due to its lower detection limits and higher accuracy.

  4. Determination of aromatic hydrocarbons in asphalt release agents using headspace solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Tang, Bing; Isacsson, Ulf

    2005-04-01

    The possibility of quantitative analysis of aromatic hydrocarbons in oil-based asphalt release agents was investigated using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS). The target analytes studied were benzene, toluene, ethylbenzene, p-, m-, and o-xylene (BTEX) and 1,3,5-trimethylbenzene and 1,2,4-trimethylbenzene. Experimental parameters influencing HS-SPME efficiency were studied (equilibration time between sample and headspace and between headspace and SPME fiber, sample amount and sample matrice effects). A HS-SPME method using hexadecane as a surrogate matrice was developed. The detection limit was estimated as 0.03-0.08 ppm (w/w) for the target analytes investigated. Good linearity was observed (R2 > 0.999) for all calibration curves at high, medium and low concentration level. The repeatability of the method (RSD, relative standard deviation) was found to be less than 10% (generally less than 5%) in triplicate samples and approximately 2% at eight consecutive tests on one and the same sample. The accuracy of the method given by recovery of spiked samples was between 85 and 106% (generally between 95 and 105%). The HS-SPME method developed was applied to four commercially available asphalt release agents. External calibration and standard addition approaches were investigated regarding accuracy. The results showed that standard addition generates higher accuracy than external calibration. The contents of target aromatic hydrocarbons in the asphalt release agents studied varied greatly from approximately 0.1-700 ppm. The method described looks promising, and could be a valuable tool for determination of aromatic hydrocarbons in different types of organic matrices. PMID:15830950

  5. The application of normal phase liquid chromatography/mass spectrometry by using coaxial continuous flow fast atom bombardment.

    PubMed

    Lawrence, D L

    1992-07-01

    This article describes the interfacing of a normal phase fused silica capillary high performance liquid chromatography system to a magnetic sector mass spectrometer by using continuous flow fast atom bombardment (CFFAB). While the performance of CFFAB using reversed phase techniques is well understood, there is very little if any documentation on interfacing nonaqueous normal phase systems with CFFAB. This article describes the use of packed fused silica capillary liquid chromatography columns and the corresponding normal phase solvent systems. The experimental parameters required with nonaqueous solvent systems differ significantly from those of aqueous solvent systems. Ditallowdimethylammonium chloride (DTDMAC), a cationic surfactant commonly used as the active ingredient in fabric softener products, was chosen as a model compound to demonstrate the technique. DTDMAC was identified in a commercially available fabric softener product by using on-line normal phase liquid chromatography/mass spectrometry with accurate mass and tandem mass spectrometry. PMID:24234501

  6. Analysis of Organic Molecules Extracted from Mars Analogues and Influence of Their Mineralogy Using N-Methyl-N-(tert-butyldimethylsilyl)Trifluoroacetamide Derivatization Coupled with Gas Chromatography Mass Spectrometry in Preparation for the Sample Analysis at Mars Derivatization Experiment on the Mars Science Laboratory Mission

    NASA Technical Reports Server (NTRS)

    Stalport, F.; Glavin, D. P.; Eigenbrode, J. L.; Bish, D.; Blake, D.; Coll, P.; Szopa, C.; Buch, A.; McAdam, A.; Dworkin, J. P.; Mahaffy, P. R.

    2012-01-01

    The search for complex organic molecules on Mars, including important biomolecules such as amino acids and carboxylic acids will require a chemical extraction and derivatization step to transform these organic compounds into species that are sufficiently volatile to be detected by gas chromatography mass spectrometry (GCMS). We have developed, a one-pot extraction and chemical derivatization protocol using N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) and dimethylformamide (DMF) for the Sample Analysis at Mars (SAM) experiment on the Mars Science Laboratory (MSL). The temperature and duration the derivatization reaction, pre-concentration of chemical derivatives, and gas chromatographic separation parameters have been optimized under SAM instrument design constraints. MTBSTFA/DMF extraction and derivatization at 300 C for several minutes of a variety of terrestrial Mars analogue materials facilitated the detection of amino acids and carboxylic acids in a surface soil sample collected from the Atacama Desert and a carbonate-rich stromatolite sample from Svalbard. However, the rapid reaction of MTBSTFA with water in several analogue materials that contained high abundances of hydrated minerals and the possible deactivation of derivatized compounds by iron oxides, as detected by XRD/XRF using the CheMin field unit Terra, proved to be highly problematic for the direct extraction of organics using MTBSTFA, The combination of pyrolysis and two different chemical derivatization methods employed by SAM should enable a wide range of organic compounds to be detected by GCMS if present on Mars,

  7. Quantitative determination of dimethyl fumarate in silica gel by solid-phase microextraction/gas chromatography/mass spectrometry and ultrasound-assisted extraction/gas chromatography/mass spectrometry.

    PubMed

    Bocchini, Paola; Pinelli, Francesca; Pozzi, Romina; Ghetti, Federica; Galletti, Guido C

    2015-06-01

    Dimethyl fumarate (DMF) is a chemical compound which has been added to silica gel bags used for preserving leather products during shipment. DMF has recently been singled out due to its ability to induce a number of medical problems in people which touch products contaminated by it. Its use as a biocide has been recently made illegal in Europe. Two different extraction techniques, namely ultrasound-assisted extraction (UAE) and solid-phase microextraction (SPME), both coupled with gas chromatography/mass spectrometry were applied to the quantitative determination of DMF in silica gel. Linearity of the methods, reproducibility and detection limits were determined. The two methods were applied to the quantification of DMF in thirty-four silica gel samples used as anti-mould agents in different leather products sold in Italy, and the obtained results were statistically compared. PMID:25939646

  8. Simultaneous determination of four designer drugs and their major metabolites by liquid chromatography-mass spectrometry.

    PubMed

    Chen, Xueguo

    2015-06-15

    A sensitive liquid chromatography-electrospray ionization-ion trap mass spectrometry (LC-ESI-ITMS) method was utilized for the simultaneous analysis of four designer drugs and their in vitro metabolites in rat liver microsome S9 fraction. Four designer drugs, including methcathinone (MC), 3,4-methylenedioxymethcathinone (MDMC), 3,4-methylenedioxy-pyrovalerone (MDPV) and 4'-methyl-?-pyrrolidinopropiophenone (MPPP), were individually incubated with rat liver microsome S9 fraction, and the incubation mixtures were pooled together and analyzed by LC-ESI-ITMS simultaneously. Besides four designer drugs, five of their main metabolites were identified via the analysis of protonated molecules and tandem mass spectrometry data. Meanwhile, the quantification analysis of four designer drugs in rat liver microsome S9 fraction was performed, the calibration curves showed good linearity in the range of 0.01-5.0?g/mL and the detection limits were below 0.03?g/mL with RSDs less than 5.9% and recovery ratios above 77.4%. The experimental results not only showed that these designer drugs could be easily metabolized in rat liver microsome, and also displayed the superiorities of the method including time and cost saving, high efficiency, sensitivity and selectivity. The studies in this study indicated that the approach could be applied in the determination of illicit drugs and their metabolites in medical, pharmaceutical and forensic investigations. PMID:25939091

  9. The off-line combination of high performance liquid chromatography and comprehensive two-dimensional gas chromatography-mass spectrometry: a powerful approach for highly detailed essential oil analysis.

    PubMed

    Tranchida, Peter Q; Zoccali, Mariosimone; Bonaccorsi, Ivana; Dugo, Paola; Mondello, Luigi; Dugo, Giovanni

    2013-08-30

    The present contribution is focused on the off-line combination of high performance liquid chromatography (HPLC) and comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC×GC-quadMS), and its application to the detailed qualitative analysis of essential oils. Specifically, a silica column was exploited for the separation of the essential oil constituents in two groups, namely hydrocarbon and oxygenated compounds. After, each HPLC-fraction was reduced in volume, and then subjected to cryogenically modulated GC×GC-quadMS analysis. The volatiles were separated on a normal-phase GC×GC column set, and identified through database matching and linear retention index information. The concentrated HPLC fractions gave origin to unexpectably crowded chromatograms, due to two fundamental GC×GC characteristics, namely the enhanced separation power and sensitivity. The results attained were particularly stimulating with regards to the oxygenated compounds, namely those constituents which contribute most to the essential oil aroma, and are of more use for the evaluation of quality and genuineness. Two genuine Citrus essential oils, bergamot and sweet orange, were subjected to analysis, and compared to applications carried out with a GC-quadMS instrument. PMID:23890548

  10. Design of experiments and detailed uncertainty analysis to develop and validate a solid-phase microextraction/gas chromatography-mass spectrometry method for the simultaneous analysis of 16 pesticides in water.

    PubMed

    Passeport, Elodie; Guenne, Angeline; Culhaoglu, Tanya; Moreau, Sylvain; Bouyé, Jean-Michel; Tournebize, Julien

    2010-08-13

    A solid-phase microextraction (SPME)/gas chromatography (GC)-mass spectrometry (MS) multiresidue analytical method was developed for 16 pesticides presenting different physicochemical properties including diphenyl ether, triazine, ureas, acetamides, benzofuran, thiocarbamate, pyridine carboxamides, chloronitrile, piperedine, and azoles. Optimization was achieved by means of the design of experiments methodology. Extraction temperature, extraction time, desorption temperature, and NaCl addition were the factors exhibiting the most significant effects on pesticide extraction. Validation was carried out through model adequacy and specificity tests, limits of quantification and detection determination, and full uncertainty assessment on the whole analytical method. Good first- and second-order model adequacy was found for pesticide calibration. LOQs were in the 0.05-0.5 microg L(-1) range and specificity recoveries varied from 75% to 140%. These results were considered acceptable for our research purposes on highly concentrated agricultural flows. Uncertainty calculations accounted for several steps: standard preparation, calibration model selection, and use. On average, real sample concentration uncertainties were lower than 10%, indicating that the analytical method performed very well. Its application to 61 real water samples confirmed the presence of some pesticide concentrations in relation to farmer use, whereas other molecules were usually either not detected or not quantified. PMID:20619842

  11. The future of liquid chromatography-mass spectrometry (LC-MS) in metabolic profiling and metabolomic studies for biomarker discovery

    PubMed Central

    Metz, Thomas O.; Zhang, Qibin; Page, Jason S.; Shen, Yufeng; Callister, Stephen J.; Jacobs, Jon M.; Smith, Richard D.

    2008-01-01

    SUMMARY The future utility of liquid chromatography-mass spectrometry (LC-MS) in metabolic profiling and metabolomic studies for biomarker discover will be discussed, beginning with a brief description of the evolution of metabolomics and the utilization of the three most popular analytical platforms in such studies: NMR, GC-MS, and LC-MS. Emphasis is placed on recent developments in high-efficiency LC separations, sensitive electrospray ionization approaches, and the benefits to incorporating both in LC-MS-based approaches. The advantages and disadvantages of various quantitative approaches are reviewed, followed by the current LC-MS-based tools available for candidate biomarker characterization and identification. Finally, a brief prediction on the future path of LC-MS-based methods in metabolic profiling and metabolomic studies is given. PMID:19177179

  12. Identification and differentiation of benzodiazepines and their metabolites in urine by computerized gas chromatography-mass spectrometry.

    PubMed

    Maurer, H; Pfleger, K

    1987-11-27

    A method for the identification and differentiation of the following benzodiazepines and their metabolites in urine after acid hydrolysis and acetylation is described: bromazepam, camazepam, chlordiazepoxide, clobazam, clonazepam, clorazepate, clotiazepam, cloxazolam, delorazepam, diazepam, ethylloflazepate, flunitrazepam, flurazepam, halazepam, ketazolam, loprazolam, lorazepam, lormetazepam, medazepam, metaclazepam, midazolam, nitrazepam, nordazepam, oxazepam, oxazolam, prazepam, quazepam, temazepam and tetrazepam. The acetylated extract was analysed by computerized gas chromatography-mass spectrometry. An on-line computer allowed rapid detection using ion chromatography with ions m/z 205, 211, 230, 241, 245, 249, 312 and 333. The identity of positive signals in the reconstructed ion chromatogram was confirmed by a comparison of the stored full mass spectra with reference spectra. The ion chromatograms, reference mass spectra and gas chromatographic retention indices (on OV-101) are documented. PMID:3437028

  13. Simultaneous determination of alachlor, metolachlor, atrazine, and simazine in water and soil by isotope dilution gas chromatography/mass spectrometry.

    PubMed

    Huang, L Q

    1989-01-01

    A multiresidue method was developed for the simultaneous determination of low parts per billion (ppb) concentrations of the herbicides alachlor, metolachlor, atrazine, and simazine in water and soil using isotope dilution gas chromatography/mass spectrometry (GC/MS). Known amounts of 15N,13C-alachlor and 2H5-atrazine were added to each sample as internal standards. The samples were then prepared by a solid phase extraction with no further cleanup. A high resolution GC/low resolution MS system with data acquisition in selected ion monitoring mode was used to quantitate herbicides in the extract. The limit of detection was 0.05 ppb for water and 0.5 ppb for soil. Accuracy greater than 80% and precision better than 4% was demonstrated with spiked samples. PMID:2651394

  14. Determination of hydramethylnon residues in grass by liquid chromatography with confirmation by liquid chromatography/mass spectrometry.

    PubMed

    Stout, S J; Peterson, R P; daCuhna, A R; Picard, G L

    1995-01-01

    An improved method for determination of hydramethylnon residues in pasture grass is described. The method uses (1) the hydrochloride salt of hydramethylnon to improve its water solubility and (2) an acid-methanol precipitation to remove chlorophylls while leaving the analyte in solution. The liquid chromatographic method has a validated sensitivity of 0.05 ppm with controls showing < 0.004 ppm. The overall average recovery from 0.05 to 0.50 ppm was 98%, with a standard deviation of 11%. Samples showing a positive response (0.05 ppm or higher) and requiring mass spectrometric confirmation are directly amenable to liquid chromatography/mass spectrometry without additional sample preparation. PMID:7756902

  15. Identification of nonecdysteroid steroids in hemolymph of both male and female Astacus leptodactylus (Crustacea) by gas chromatography-mass spectrometry.

    PubMed

    Ollevier, F; De Clerck, D; Diederik, H; De Loof, A

    1986-02-01

    The O-pentafluorobenzyloxime (OPFB)-heptafluorobutyrylester (HFB) derivatives of hemolymph steroid extracts from both male and female Astacus leptodactylus were subjected to negative ion chemical ionization and capillary gas chromatography-mass spectrometry (NCI/GC-MS). Five nonecdysteroid steroids, namely pregnenolone, 17 alpha-hydroxypregnenolone, testosterone, cholesterol, and 6 beta-hydroxyprogesterone were identified. With selected ion monitoring (SIM), indications were found for the presence of four more steroids: androstenedione, 5 alpha-dihydrotestosterone, 11-ketotestosterone, and 11 beta-hydroxytestosterone. The presence of 6 beta-hydroxyprogesterone could only be demonstrated in the female hemolymph. With the technique used, dehydroepiandrosterone, progesterone, 17 alpha-hydroxyprogesterone, and estrogens could not be detected in male or female hemolymph extracts. PMID:2937682

  16. Determination of some volatile compounds in alcoholic beverage by headspace solid-phase microextraction gas chromatography - mass spectrometry

    NASA Astrophysics Data System (ADS)

    Schmutzer, G.; Avram, V.; Feher, I.; David, L.; Moldovan, Z.

    2012-02-01

    The volatile composition of alcoholic beverage was studied by headspace solid-phase microextraction (HSSPME) method and gas chromatography - mass spectrometry (GC-MS). Some volatile compounds, such as alcohols, esters, terpenes and other are mainly responsible for the flavor of fortified wines and their amounts specify the quality of the alcoholic beverages. From this perspective it is interesting to develop a rapid, selective and sensitive analytical method suitable for simultaneous quantification of the main molecules being responsible for the organoleptic characteristic of alcoholic beverages. Vermouth fortified drink was analyzed in order to characterize the volatile profile. Using the HS-SPME/GC-MS a number of twenty-six volatile compounds from a commercial market alcoholic beverage were identified. The most abundant compounds were m-thymol, o-thymol and eugenol, alongside of the ethyl ester compounds.

  17. Absence of sugars in electrophoretically purified cytochrome b5 demonstrated by combined gas chromatography-mass spectrometry

    PubMed Central

    1981-01-01

    The problem of determining small but significant amounts of carbohydrates, in purified proteins, has been studied using the membrane protein, cytochrome b5. A newly developed method that involves direct gas chromatography-mass spectrometry of sugars obtained by hydrolysis of proteins purified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE) allows the identification and determination of small amounts of carbohydrates (e.g., 20 micrograms of glycoprotein containing a minimum of 0.1% monosaccharide), even in the presence of relatively high amounts of impurities. Application of this method to cytochrome b5 fragments obtained by tryptic digestion from rat liver microsomes and purified by combined gel filtration and ion exchange chromatography, followed by SDS PAGE, has consistently yielded values below 0.07 mol of the individual sugars and aminosugars per mole cytochrome b5. It is concluded that cytochrome b5, at least its trypsin-released major amino- terminal fragment, is not constitutively glycosylated. PMID:7251667

  18. The future of liquid chromatography-mass spectrometry in metabolic profiling and metabolomic studies for biomarker discovery.

    SciTech Connect

    Metz, Thomas O.; Zhang, Qibin; Page, Jason S.; Shen, Yufeng; Callister, Stephen J.; Jacobs, Jon M.; Smith, Richard D.

    2007-06-01

    The future utility of liquid chromatography-mass spectrometry (LC-MS) in metabolic profiling and metabolomic studies for biomarker discover will be discussed, beginning with a brief description of the evolution of metabolomics and the utilization of the three most popular analytical platforms in such studies: NMR, GC-MS, and LC-MS. Emphasis is placed on recent developments in high-efficiency LC separations and sensitive electrospray ionization approaches and the benefits to incorporating both in LC-MS-based approaches. The advantages and disadvantages of various quantitative approaches are reviewed, followed by the current LC-MS-based tools available for candidate biomarker characterization and identification. Finally, a brief prediction on the future path of LC-MS-based methods in metabolic profiling and metabolomic studies is given.

  19. Determination of quaternary ammonium compounds in seawater samples by solid-phase extraction and liquid chromatography-mass spectrometry.

    PubMed

    Bassarab, P; Williams, D; Dean, J R; Ludkin, E; Perry, J J

    2011-02-01

    A method for the simultaneous determination of two biocidal quaternary ammonium compounds; didecyldimethylammonium chloride (didecyldimethyl quat) and dodecylbenzyldimethylammonium chloride (benzyl quat), in seawater by solid phase extraction (SPE) followed by liquid chromatography-mass spectrometry (LC-MS) was developed. The optimised procedure utilised off-line extraction of the analytes from seawater using polymeric (Strata-X) SPE cartridges. Recoveries ranged from 80 to 105%, with detection limits at the low parts-per-trillion (ng/l) level for both analytes. To demonstrate sensitivity, environmental concentrations were measured at three different locations along the North East coast of England with measured values in the range 120-270ng/l. PMID:21194696

  20. Identification of Flavor Components in Perfumes by Headspace Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Knupp, Gerd; Kusch, Peter; Neugebauer, Michael

    2002-01-01

    An experiment for identification of flavor components in Original Eau de Cologne by headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS) with electron impact ionization was developed. A new SPME fiber with a dual coating of divinylbenzene and Carboxen, each suspended in polydimethylsiloxane, was used. The compounds were identified by search of the NIST 98 MS Library or by comparison with pure standards. The experiment was developed for second-year chemistry students to learn the principles of analytical instrumentation (GC-MS) and sample preparation techniques (HS-SPME). The students are able to complete this experiment in a single four-hour laboratory session.

  1. Liquid-liquid extraction and liquid chromatography-mass spectrometry detection of curcuminoids from bacterial culture medium.

    PubMed

    Tan, Suryani; Rupasinghe, Thusitha W T; Tull, Dedreia L; Augustin, Mary Ann; Gras, Sally L

    2015-04-15

    Liquid chromatography-mass spectrometry (LC-MS) has been used to detect polyphenolic curcuminoids found in turmeric but studies of metabolism by bacterial and mammalian cells in vitro are compromised by poor recovery from the culture medium. We report a liquid-liquid extraction procedure with ethyl acetate and use LC-MS to quantify extracted curcuminoids. Ethyl acetate allows recoveries of ? 80-86% of curcuminoids from the bacterial growth medium, bacterial cell lysate and combined bacterial cell and growth medium matrices; a clear improvement over acetonitrile where recoveries were ? 25-66%. This optimised method will enable studies of curcuminoid metabolism and may be applicable to other hydrophobic polyphenolic compounds. PMID:25770788

  2. Core-shell polydopamine magnetic nanoparticles as sorbent in micro-dispersive solid-phase extraction for the determination of estrogenic compounds in water samples prior to high-performance liquid chromatography-mass spectrometry analysis.

    PubMed

    Socas-Rodríguez, Bárbara; Hernández-Borges, Javier; Salazar, Pedro; Martín, Miriam; Rodríguez-Delgado, Miguel Ángel

    2015-06-01

    In this work, core-shell Fe3O4@poly(dopamine) magnetic nanoparticles (m-NPs) were prepared and characterized in our laboratory and applied as sorbents for the magnetic-micro solid phase extraction (m-?SPE) of twelve estrogenic compounds of interest (i.e. 17?-estradiol, 17?-estradiol, estrone, hexestrol, 17?-ethynylestradiol, diethylstibestrol, dienestrol, zearalenone, ?-zearalanol, ?-zearalanol, ?-zearalenol and ?-zearalenol) from different water samples. Separation, determination and quantification were achieved by high-performance liquid chromatography coupled to ion trap mass spectrometry with electrospray ionization. NPs@poly(dopamine) were synthesized by a chemical coprecipitation procedure and characterized by different surface characterization techniques (X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis, transmission and scanning electron microscopy, infrared and Raman spectroscopy, vibrating sample magnetometry, microelectrophoresis and adsorption/desorption isotherms). Parameters affecting the extraction efficiency of m-?SPE (i.e. polymerization time, pH of the sample, extraction and elution conditions) were studied and optimized. The methodology was validated for Milli-Q, mineral, tap and wastewater using 2-methoxyestradiol as internal standard, obtaining recoveries ranging from 70 to 119% with relative standard deviation values lower than 20% and limits of quantification in the range 0.02-1.1?g/L. PMID:25917309

  3. Determination of testosterone in saliva and blow of bottlenose dolphins (Tursiops truncatus) using liquid chromatography-mass spectrometry.

    PubMed

    Hogg, C J; Vickers, E R; Rogers, T L

    2005-01-25

    A rapid, accurate and reproducible assay utilising high performance liquid chromatography-mass spectrometry (LC-MS) has been developed and validated for determining testosterone concentrations in saliva and blow of bottlenose dolphins. Sample preparation used solid phase extraction with specific preconditioning of cartridges. Analytes were eluted with 100% acetonitrile, dried under nitrogen and stored at -80 degrees C. Samples were reconstituted in 60% acetonitrile for LC-MS analysis. Chromatographic separation was achieved with an Alltech Macrosphere C8 stainless steel analytical column (2.1 mm x 150 mm i.d., 5 microm particle size, 300 angstroms pore size) using a 55% mobile phase B isocratic method (mobile phase A = 0.5% acetic acid; mobile phase B = 0.5% acetic acid, 90% acetonitrile). Samples were analysed in SIM at m/z 289.20 (testosterone mw 288.40) and a positive ion ESI. The limit of quantification was 0.5 ng/ml with a limit of detection of 0.2 ng/ml. The concentration curve was linear from 0.5 to 50 ng/ml (y = 0.01x + 0.0045, r(2) = 0.959, r = 0.979, p < 0.001). The R.S.D.s of intra- and inter-batch precision were less than 15% for saliva and 11% blow. Recovery of the assay for saliva was 93.0 +/- 7.9% (50 ng/ml) and 91.5 +/- 3.72% (1 ng/ml), and for blow was 83.3 +/- 6.8% (50 ng/ml) and 85.8 +/- 4.6% (1 ng/ml). Recovery of the internal standard in saliva was 73.0 +/- 14.2% and in blow was 78.63 +/- 4.29. The described assay was used to determine the presence of endogenous testosterone in saliva (9.73-23 ng/ml, n = 10) and blow (14.71-86.20 ng/ml, n = 11) samples of captive bottlenose dolphins. PMID:15639457

  4. Determination of Phytochelatins in Rice by Stable Isotope Labeling Coupled with Liquid Chromatography-Mass Spectrometry.

    PubMed

    Liu, Ping; Cai, Wen-Jing; Yu, Lei; Yuan, Bi-Feng; Feng, Yu-Qi

    2015-07-01

    A highly sensitive method was developed for the detection of phytochelatins (PCs) in rice by stable isotope labeling coupled with liquid chromatography-electrospray ionization-tandem mass spectrometry (IL-LC-ESI-MS/MS) analysis. A pair of isotope-labeling reagents [?-bromoacetonylquinolinium bromide (BQB) and BQB-d(7)] were used to label PCs in plant sample and standard PCs, respectively, and then combined prior to LC/MS analysis. The heavy labeled standards were used as the internal standards for quantitation to minimize the matrix and ion suppression effects in MS analysis. In addition, the ionization efficiency of PCs was greatly enhanced through the introduction of a permanent charged moiety of quaternary ammonium of BQB into PCs. The detection sensitivities of PCs upon BQB labeling improved by 14-750-fold, and therefore, PCs can be quantitated using only 5 mg of plant tissue. Furthermore, under cadmium (Cd) stress, we found that the contents of PCs in rice dramatically increased with the increased concentrations and treatment time of Cd. It was worth noting that PC5 was first identified and quantitated in rice tissues under Cd stress in the current study. Taken together, this IL-LC-ESI-MS/MS method demonstrated to be a promising strategy in detection of PCs in plants with high sensitivity and reliability. PMID:26073168

  5. Resolution of co-eluting compounds of Cannabis Sativa in comprehensive two-dimensional gas chromatography/mass spectrometry detection with Multivariate Curve Resolution-Alternating Least Squares.

    PubMed

    Omar, Jone; Olivares, Maitane; Amigo, José Manuel; Etxebarria, Nestor

    2014-04-01

    Comprehensive Two Dimensional Gas Chromatography - Mass Spectrometry (GC × GC/qMS) analysis of Cannabis sativa extracts shows a high complexity due to the large variety of terpenes and cannabinoids and to the fact that the complete resolution of the peaks is not straightforwardly achieved. In order to support the resolution of the co-eluted peaks in the sesquiterpene and the cannabinoid chromatographic region the combination of Multivariate Curve Resolution and Alternating Least Squares algorithms was satisfactorily applied. As a result, four co-eluting areas were totally resolved in the sesquiterpene region and one in the cannabinoid region in different samples of Cannabis sativa. The comparison of the mass spectral profiles obtained for each resolved peak with theoretical mass spectra allowed the identification of some of the co-eluted peaks. Finally, the classification of the studied samples was achieved based on the relative concentrations of the resolved peaks. PMID:24607138

  6. Characterisation of the aroma profiles of different honeys and corresponding flowers using solid-phase microextraction and gas chromatography-mass spectrometry/olfactometry.

    PubMed

    Seisonen, Sirli; Kivima, Evelin; Vene, Kristel

    2015-02-15

    The aroma profiles of thirteen different honey samples from four botanical origins: heather (Calluna vulgaris), raspberry (Rubus idaeus), rape (Brassica napus), alder buckthorn (Frangula alnus) and the blossoms of the four corresponding flowers were investigated to find odour-active compounds exclusively representing specific honeys based on odour-active compounds from the blossoms. Gas-chromatography-mass spectrometry (GC-MS) and gas-chromatography-olfactometry were used to determine and identify the odour-active compounds. Data was analysed using agglomerative hierarchical clustering and correspondence analysis. Honeys from the same botanical origin clustered together; however, none of the identified compounds were exclusive to a particular honey/blossom combination. Heather honey had the flavour profile most different to the others. Isophorone and 2-methylbutyric acid were found only in heather honeys. Heather honey was characterised by having more "sweet" and "candy-like" notes, raspberry honeys had more "green" notes, while alder buckthorn had more "honey" and "floral" notes. PMID:25236195

  7. Applications of solid-phase microextraction and gas chromatography/mass spectrometry (SPME-GC/MS) in the study of grape and wine volatile compounds.

    PubMed

    Panighel, Annarita; Flamini, Riccardo

    2014-01-01

    Volatile compounds are responsible for the wine "bouquet", which is perceived by sniffing the headspace of a glass, and of the aroma component (palate-aroma) of the overall flavor, which is perceived on drinking. Grape aroma compounds are transferred to the wine and undergo minimal alteration during fermentation (e.g., monoterpenes and methoxypyrazines); others are precursors of aroma compounds which form in winemaking and during wine aging (e.g., glycosidically-bound volatile compounds and C13-norisoprenoids). Headspace solid phase microextraction (HS-SPME) is a fast and simple technique which was developed for analysis of volatile compounds. This review describes some SPME methods coupled with gas chromatography/mass spectrometry (GC/MS) used to study the grape and wine volatiles. PMID:25529017

  8. Metabolomic profiling of human follicular fluid from patients with repeated failure of in vitro fertilization using gas chromatography/mass spectrometry

    PubMed Central

    Xia, Lan; Zhao, Xiaoming; Sun, Yun; Hong, Yan; Gao, Yuping; Hu, Shuanggang

    2014-01-01

    Objective: To establish a gas chromatography/mass spectrometry (GC/MS)-based metabolomics method to compare the metabolites in the follicular fluid (FF) from patients with in vitro fertilization (IVF) and repeated IVF failure (RIF). Methods: A prospective study was employed in Center for Reprodutive Medcine, Renji Hospital, Shanghai, China, between January and October 2010. FF samples were collected from 13 patients with RIF and 15 patients who achieved pregnancy after the first IVF cycle. Results: Partial least squares (PLS) discriminant analysis of the PCA data revealed that the samples were scattered into two different regions. FF from the two groups differed with respect to 20 metabolites. FF from RIF group showed elevated levels of several amino acids (valine, threonine, isoleucine, cysteine, serine, proline, alanine, phenylalanine, lysine, methionine and ornithine), and reduced levels of dicarboxylic acids, cholesterol and some organic acids. Conclusions: The studies corroborated successful determination of the levels of metabolite in the FF. PMID:25400819

  9. An empirical Bayes model using a competition score for metabolite identification in gas chromatography mass spectrometry

    PubMed Central

    2011-01-01

    Background Mass spectrometry (MS) based metabolite profiling has been increasingly popular for scientific and biomedical studies, primarily due to recent technological development such as comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GCxGC/TOF-MS). Nevertheless, the identifications of metabolites from complex samples are subject to errors. Statistical/computational approaches to improve the accuracy of the identifications and false positive estimate are in great need. We propose an empirical Bayes model which accounts for a competing score in addition to the similarity score to tackle this problem. The competition score characterizes the propensity of a candidate metabolite of being matched to some spectrum based on the metabolite's similarity score with other spectra in the library searched against. The competition score allows the model to properly assess the evidence on the presence/absence status of a metabolite based on whether or not the metabolite is matched to some sample spectrum. Results With a mixture of metabolite standards, we demonstrated that our method has better identification accuracy than other four existing methods. Moreover, our method has reliable false discovery rate estimate. We also applied our method to the data collected from the plasma of a rat and identified some metabolites from the plasma under the control of false discovery rate. Conclusions We developed an empirical Bayes model for metabolite identification and validated the method through a mixture of metabolite standards and rat plasma. The results show that our hierarchical model improves identification accuracy as compared with methods that do not structurally model the involved variables. The improvement in identification accuracy is likely to facilitate downstream analysis such as peak alignment and biomarker identification. Raw data and result matrices can be found at http://www.biostat.iupui.edu/~ChangyuShen/index.htm Trial Registration 2123938128573429 PMID:21985394

  10. Simultaneous determination of nine flavonoids in Polygonum hydropiper L. samples using nanomagnetic powder three-phase hollow fibre-based liquid-phase microextraction combined with ultrahigh performance liquid chromatography–mass spectrometry

    Microsoft Academic Search

    Xian Yang; Bo-Chu Wang; Xue Zhang; Shui-Ping Yang; Wei Li; Qian Tang; Gurinder K. Singh

    2011-01-01

    A simple, inexpensive, and efficient nanomagnetic powder three-phase hollow fibre-based liquid-phase microextraction (HF-LPME) technique combined with ultrahigh performance liquid chromatography–mass spectrometry (UPLC–MS) was developed for the simultaneous analysis of nine flavonoids in Polygonum hydropiper L. samples. The final, optimised extraction conditions were as follows: an organic solvent of ethyl acetate, a donor phase of aqueous KH2PO4 at pH 3.0, an

  11. Determination of off-flavor compounds, 2-methylisoborneol and geosmin, in salmon fillets using stir bar sorptive extraction–thermal desorption coupled with gas chromatography–mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A sensitive and solvent-less method for the determination of musty and earthy off-flavor compounds, 2-methylisoborneol (MIB) and geosmin (GSM), in salmon tissue was developed using stir bar sorptive extraction -thermal desorption coupled with gas chromatography -mass spectrometry (SBSE -TD -GCMS). M...

  12. DETERMINATION OF 5-METHYLTETRAHYDROFOLIC ACID IN HUMAN SERUM BY STABLE-ISOTOPE DILUTION HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This report describes a stable isotope liquid chromatography-mass spectrometry (LC-MS) method that was developed for the quantitative determination of 5-methyltetrahydrofolic acid (5-MTHFA) and folic acid in a variety of citrus juices. Folates were extracted from juices and the polyglutamyl side ch...

  13. Sublimation extraction coupled with gas chromatography-mass spectrometry: A new technique for future in situ analyses of purines and pyrimidines on Mars

    Microsoft Academic Search

    D. P. Glavin; H. J. Cleaves; A. Buch; M. Schubert; A. Aubrey; J. L. Bada; P. R. Mahaffy

    2006-01-01

    We have developed a sublimation technique coupled with chemical derivatization and gas chromatography mass spectrometry (GC-MS) to detect nucleobases and other volatile organic compounds derived from bacteria in Mars analog materials. To demonstrate this technique, a sample of serpentine inoculated with Escherichia coli (E. coli) cells was heated to 500°C for several seconds under Martian ambient pressure. The sublimate was

  14. In situ derivatization reaction and determination of ibuprofen in water samples using headspace generation-programmed temperature vaporization-gas chromatography-mass spectrometry

    Microsoft Academic Search

    José Luis Pérez Pavón; Ana María Casas Ferreira; María Esther Fernández Laespada; Bernardo Moreno Cordero

    2009-01-01

    The aim of the present work is to propose a method for the determination of ibuprofen, as a typical representative of pharmaceutical compounds, in aqueous samples. To do so, an in situ derivatization reaction in aqueous medium was employed in the vial of a headspace sampler (HS), after which instrumental measurements were made with gas chromatography-mass spectrometry (GC-MS). As the

  15. DETERMINATION OF A BOUND MUSK XYLENE METABOLITE IN CARP HEMOGLOBIN AS A BIOMARKER OF EXPOSURE BY GAS CHROMATOGRAPHY MASS SPECTROMETRY USING SELECTED ION MONITORING

    EPA Science Inventory

    Musk xylene (MX) is widely used as a fragrance ingredient in commercial toiletries. Identification and quantification of a bound 4-amino-MX (AMX) metabolite was carried out by gas chromatography-mass spectrometry (GC/MS), with selected ion monitoring (SIM). Detection of AMX occur...

  16. Chromatography–mass spectrometry studies on the metabolism of synthetic cannabinoids JWH-018 and JWH-073, psychoactive components of smoking mixtures

    Microsoft Academic Search

    Andrej Grigoryev; Sergey Savchuk; Aleksandra Melnik; Natal’ja Moskaleva; Jurij Dzhurko; Mihail Ershov; Aleksandr Nosyrev; Aleksandr Vedenin; Boris Izotov; Irina Zabirova; Vladimir Rozhanets

    2011-01-01

    The Russian Federation prohibited the distribution of herbal mixtures with synthetic aminoalkylindoles JWH-018 and JWH-073, agonist cannabinoid receptors, on January 22, 2010. The lack or low content of their native compounds in urine requires detailed identification of their metabolites, which are excreted with urine and are present in blood. Using gas and liquid chromatography–mass spectrometry, we identified a series of

  17. Analytical method for the quantitative determination of cyanuric acid as the degradation product of sodium dichloroisocyanurate in urine by liquid chromatography mass spectrometry

    Microsoft Academic Search

    Katan Patel; Kate Jones

    2007-01-01

    A simple and selective analytical method for the quantitative determination of cyanuric acid, the degradation product of sodium dichloroisocyanurate (NaDCC), in human urine is reported herein. The sample preparation involved the use of diatomaceous earth extraction columns. Quantification was achieved by liquid chromatography mass spectrometry using negative ion electrospray with a cyano (CN) column. Between day relative standard deviation less

  18. Detection of aldehydes in lung cancer cell culture by gas chromatography/mass spectrometry and solid-phase microextraction with on-fiber derivatization

    E-print Network

    Shan, Guangqing

    2007-09-17

    on the fiber. Finally, the aldehyde oximes formed on the fiber were analyzed by gas chromatography/mass spectrometry (GC/MS). Using this method, acetaldehyde decrease was found in both non-small lung cancer cell cultures studied compared to the medium control...

  19. Thermal Extraction?Two-Dimensional Gas Chromatography?Mass Spectrometry with Heart-Cutting for Nitrogen Heterocyclics in Biomass Burning Aerosols

    EPA Science Inventory

    A thermal extraction-two-dimensional gas chromatography-mass spectrometry (TE-GC-MS) method (with heart-cutting) is developed for quantitatively assessing nitrogen (N-bearing organic species (e.g., pyrrole, pyridine, nitriles, and amines) in aerosols emitted from agricultural fir...

  20. Rapid screening procedures for the hydrolysis products of chemical warfare agents using positive and negative ion liquid chromatography–mass spectrometry with atmospheric pressure chemical ionisation

    Microsoft Academic Search

    Robert W Read; Robin M Black

    1999-01-01

    Qualitative screening procedures have been developed for the rapid detection and identification of the hydrolysis products of chemical warfare agents in aqueous samples and extracts, using liquid chromatography–mass spectrometry with positive and negative atmospheric pressure chemical ionisation (APCI). Previously reported screening procedures, which used positive APCI or electrospray ionisation (ESI), were modified by using LC conditions that allowed acquisition of

  1. Solidphase extraction and gas chromatography–mass spectrometry determination of kaempferol and quercetin in human urine after consumption of Ginkgo biloba tablets

    Microsoft Academic Search

    D. G. Watson; E. J. Oliveira

    1999-01-01

    A method was developed for the quantification of the flavonoids quercetin and kaempferol in human urine using a solid-phase extraction procedure followed by gas chromatography–mass spectrometry. Deuterated internal standards of the analytes were spiked into the samples prior to extraction. The limit of detection of the method was ca. 10 pg on column and precision of the method for quantification

  2. Fast determination of octinoxate and oxybenzone uv filters in swimming pool waters by gas chromatography/mass spectrometry after solid-phase microextraction.

    PubMed

    Y?lmazcan, Ö; Kanakaki, C; Izgi, B; Rosenberg, E

    2015-07-01

    A fast gas chromatography/mass spectrometry method was developed and validated for the analysis of the potential endocrine disrupters octinoxate and oxybenzone in swimming pool water samples based on the solvent-free solid-phase microextraction technique. The low-pressure gas chromatography/mass spectrometry method used for the fast identification of UV filter substances was compared to a conventional method in terms of sensitivity and speed. The fast method proposed resulted in 2 min runs, leading to an eightfold decrease in the total analysis time and a sevenfold improvement in detection limits. The main parameters affecting the solid-phase microextraction process were also studied in detail and the optimized conditions were as follows: fiber coating, polyacrylate; extraction mode, direct immersion; extraction temperature, 25°C; sample volume, 5 mL; extraction time 45 min; pH 6.5. Under the optimized conditions, a linear response was obtained in the concentration range of 0.5-25 ?g/L with correlation coefficients in the range 0.990-0.999. The limits of detection were 0.17-0.29 ?g/L, and the recoveries were 80-83%. Combined method uncertainty was assessed and found to be less than 7% for both analytes for concentrations equal to or higher than 5 ?g/L. Pool water samples were analyzed to demonstrate the applicability of the proposed method. Neither octinoxate nor oxybenzone were detected in the swimming pool water samples at concentrations above the respective limits of detection. PMID:25931007

  3. Characterization of ultra-thin polymeric films by Gas chromatography-Mass spectrometry hyphenated to thermogravimetry.

    PubMed

    Gianotti, Valentina; Antonioli, Diego; Sparnacci, Katia; Laus, Michele; Giammaria, Tommaso Jacopo; Ceresoli, Monica; Ferrarese Lupi, Federico; Seguini, Gabriele; Perego, Michele

    2014-11-14

    Polymeric materials are widely employed to build up tunable nanomasks for nano-patterning technologies. Ultrathin polymer layers are involved in this process. A Thermo Gravimetric Analysis-Mass Spectrometry (TGA-GC-MS) method was optimised, validated and successfully applied to investigate the thermal behavior of ultrathin poly(styrene-r-methylmethacrylate) random copolymer layers P(S-r-MMA) grafted to a silicon wafer surface. The interface between TGA and MS is highly versatile since many instrumental parameters (i.e. loop volumes, pulsed sampling frequencies, acquisition modalities, carrier gases, flow rates) can be easily tuned. Samples featuring substantial scale difference, i.e. bulk materials, thick films (few ?m thickness), thin and ultrathin films (few nm thickness) can be analyzed without any instrumental modification or sample pretreatments. The TGA-GC-MS analysis was used to highlight subtle differences in samples featuring different thicknesses, in the 2-6 nm range, and subjected to various thermal treatments, thus indicating that this hyphenated technique could be successfully applied to the investigation of ultrathin polymer films. PMID:25311490

  4. Plasma lipidomic profiling method based on ultrasound extraction and liquid chromatography mass spectrometry.

    PubMed

    Pizarro, Consuelo; Arenzana-Rámila, Irene; Pérez-del-Notario, Nuria; Pérez-Matute, Patricia; González-Sáiz, José-María

    2013-12-17

    Lipidomics is an emerging field in biomedical research that includes the analysis of all the lipids present in complex biological samples. To evaluate the chemical and biological diversity of lipids, lipid extraction is usually the first step toward lipidomics analysis. Nevertheless, sample preparation is still a time-consuming and error prone analytical step. Therefore, the development of simple and robust methods suitable for high-throughput lipid analysis is of great interest. This study presents a new method for exhaustive lipid fingerprinting of human blood plasma samples based on the employment of methyl tert-butyl ether (MTBE) and ultrasound (US) energy combined with liquid chromatography-electrospray ionization quadrupole-time-of-flight mass spectrometry (LC-ESIqToF-MS). First, the MTBE-US extraction step was optimized by means of experimental design methodology. After the optimization step, a comparative study was performed to assess the suitability of the proposed method. The new method allowed extraction time to be reduced to half, in comparison with previously reported methods. The proposed method also allowed increasing extraction repeatability (with RSDs below 5.55%) and efficiency (recoveries higher than 70% were obtained for all lipids evaluated). Moreover, the new proposed method enables more than 800 different features to be detected. Thus, the overall number of lipids identified with the databases for this novel extraction method (352) was the highest of the evaluated methods. The efficiency, precision, and feature detection capacity of the proposed method confirmed its suitability for the evaluation of the lipid profile of human blood plasma samples. Moreover, taking into account its simplicity, low time consumption, and compatibility with automation, the new proposed method could be a suitable alternative to previously reported methods for use in laboratories for comprehensive lipidomic profiling. PMID:24266777

  5. Automated electric-field-driven membrane extraction system coupled to liquid chromatography-mass spectrometry.

    PubMed

    See, Hong Heng; Hauser, Peter C

    2014-09-01

    An automated analyte electroextraction and preconcentration system, which was used as the front end for a liquid chromatography-electrospray mass spectrometry instrument, is described. The extraction was based on driving the anionic analytes across a polymer inclusion membrane by application of a potential of 200 V to the cell. Five milliliters (5 mL) of sample were passed through a flow-through cell at a flow rate of 0.2 mL/min containing a membrane 20 ?m thick. This consisted of 75% cellulose triacetate as base polymer, 12.5% of tris(2-ethylhexyl)phosphate as plasticizer, and 12.5% of Aliquat 336 as cationic carrier. The target analytes were enriched in 20 ?L of a stagnant acceptor solution prior to online LC/MS analysis. The performance of the system was demonstrated for the determination of chlorinated phenoxyacetic acid herbicides in spiked river water. Enrichment factors of ~200 were achieved with recoveries of typically 99% and precision values of typically 5%. The limit of detection (LOD) values were found to be between 0.03 ng/mL to 0.08 ng/mL. PMID:25111065

  6. Determination of polyphenolic compounds by liquid chromatography-mass spectrometry in Thymus species.

    PubMed

    Boros, Borbála; Jakabová, Silvia; Dörnyei, Agnes; Horváth, Györgyi; Pluhár, Zsuzsanna; Kilár, Ferenc; Felinger, Attila

    2010-12-17

    Polyphenolic compounds represent a wide group of phytochemicals, including well-known subgroups of phenolic acids, flavonoids, natural dyes, lignans etc., which are produced by plants. These natural bioactive compounds possess a variety of beneficial effects including antioxidant and anticarcinogenic activities, protection against coronary diseases as well as antimicrobial properties. Thymus species have already been reported as sources of different phenolic acids and flavonoids. Moreover, the composition and content of flavonoids in Thymus species play important role as taxonomic markers providing distinction of species. High-performance liquid chromatography (HPLC) coupled with diode array detector (DAD) and on-line mass spectrometry (ESI-MS) method was used for analysis. The method was evaluated for a number of validation characteristics (repeatability and intermediate precision, LOD, LOQ, calibration range, and recovery). The polyphenolic pattern of five native Hungarian Thymus species (T. glabrescens Willd., T. pannonicus All., T. praecox Opiz, T. pulegioides L., and T. serpyllum L.) was characterized. The dominant compound was rosmarinic acid, which ranged between 83.49 ?g g(-1) and 1.436 mg g(-1). Other phenolic acids (ferulic acid, caffeic acid and its other derivatives, chlorogenic acid and p-coumaric acids) were present in every examined Thymus species, as well as flavanones: naringenin, eriodictyol and dihydroquercetin; flavones: apigenin and apigenin-7-glucoside, flavonols: quercetin and rutin. The polyphenolic pattern was found to be a useful additional chemotaxonomic tool for classification purposes and determination of the locality of origin. PMID:20692666

  7. Rapid screening natural-origin lipase inhibitors from hypolipidemic decoctions by ultrafiltration combined with liquid chromatography-mass spectrometry.

    PubMed

    Xiao, Shun; Yu, Runru; Ai, Ni; Fan, Xiaohui

    2015-02-01

    Lipase inhibitors generate hypolipidemic effect that is helpful to control or treat some obesity diseases by inactivating catalytic activity of human pancreatic lipase, a key enzyme involved in triglyceride hydrolysis in vivo. Many traditional Chinese medicine (TCM) formulae have been effectively used to treat obesity and other fat related diseases for centuries and modern biological experiments demonstrate therapeutic effect of these formulae can be linked to their lipid-lowering capability in blood. These observations suggest that these hypolipidemic decoctions (HDs) could be a promising resource of natural-origin lipase inhibitors. This work described a rapid approach for screening lipase inhibitors from four widely used HDs, including Wu-Ling-San (WLS), Ze-Xie decoction (ZX), Xiao-Xian-Xiong decoction (XXX) and Xiao-Chai-Hu decoction (XCH), by ultrafiltration combing with high performance liquid chromatography-mass spectrometry (HPLC-MS). Our results showed sixteen natural-origin lipase inhibitors were discovered and identified by high resolution and multistage mass spectrometry. Inhibitory activities of two compounds were confirmed by a functional assay of lipase, which validated the reliability of our approach. Molecular docking simulation was then performed to investigate potential mechanism of action for these compounds. Together we present an efficient method for rapid screening lipase inhibitors from complex natural products, which can be easily accommodated to other important enzymatic system with therapeutic values. PMID:25481087

  8. Development and Validation of Liquid Chromatography-Mass Spectrometry Method for the Estimation of Rifampicin in Plasma

    PubMed Central

    Patil, J. S.; Suresh, Sarasija; Sureshbabu, A. R.; Rajesh, M. S.

    2011-01-01

    A selective, rapid and sensitive liquid chromatography-mass spectrometry method was developed for the quantitative estimation of rifampicin in plasma. With phenacetin as internal standard, sample pretreatment involved a one-step extraction with ethyl acetate from plasma. The sample was analyzed using methanol: 2mM ammonium acetate: 80:20 v/v as mobile phase. Chromatographic separation was achieved on a BDS Hypersil Gold C18 column which was followed by detection with mass spectrometry. Linear calibration curves were obtained in the concentration range of 5.021-1008.315 ng/ml. The inter- and intra-day accuracy values were below 15% at all quality control levels. Percent recoveries for rifampicin at high, middle and low quality control samples was obtained 55.15, 48.65 and 49.62%, respectively and for internal standard was 60.22%. Rifampicin was found stable through all validation parameters. Developed method was found to be simple, precise, accurate and rapid for estimation of rifampicin in plasma. Thus, the method can be employed for routine pharmacokinetic and bioequivalence studies. PMID:22923869

  9. Characterization of currently marketed heparin products: reversed-phase ion-pairing liquid chromatography mass spectrometry of heparin digests.

    PubMed

    Brustkern, Adam M; Buhse, Lucinda F; Nasr, Moheb; Al-Hakim, Ali; Keire, David A

    2010-12-01

    Here we report results from the analyses by enzymatic digestion and reversed-phase ion-pairing liquid chromatography mass spectrometry (RPIP-LC-MS) of active pharmaceutical ingredient (API) unfractionated heparins (UFHs) from six different manufacturers and one USP standard sample. We employed a reverse phase ion-pairing chromatography method using a C(18) column and hexylamine as the ion-pairing reagent with acetonitrile gradient elution to separate disaccharides generated from the digestion of the heparins by lyase I and III (E.C. 4.2.2.7 and 4.2.2.8) before introduction into an ion-trap mass spectrometer by an electrospray ionization (ESI) interface. Extracted ion chromatograms (EICs) were used to determine the relative abundance of the disaccharides by mass spectrometry. Eight disaccharides were observed and a similar composition profile was observed from digests of 20 UFH samples. The compositional profile determined from these experiments provides a measure of the norm and range of variation in "good" heparin to which future preparations can be compared. Furthermore, the profile obtained in the RPIP-LC-MS assay is sensitive to the presence of the contaminant, oversulfated chondroitin sulfate A (OSCS), in heparin. PMID:21069966

  10. Determination of glycols in biological specimens by gas chromatography-mass spectrometry.

    PubMed

    Gembus, Vincent; Goullé, Jean-Pierre; Lacroix, Christian

    2002-01-01

    A simple extraction and derivatization procedure for the analysis of eight glycols (ethylene glycol, EG; diethylene glycol, DEG; triethylene glycol, TEG; 1,2-propanediol, 1,2-PD; 1,3-propanediol, 1,3-PD; 1,2-butanediol, 1,2-BD; 2,3-butanediol, 2,3-BD; and hexylene glycol, HXG) using a 2-microL serum or blood sample is described. Following deproteinisation with acetonitrile, derivatization to its mono or di TMS derivative, glycols were detected using gas chromatography-electron impact mass spectrometry equipped with a split-spitless inlet and a DB-5MS column in the scan mode from 40 to 500 amu. Gamma-hydroxybutyrate-d6 (GHB-d6) was used as the internal standard. The limits of detection and quantitation in 2 pL of serum ranged, respectively, from 0.7 mg/L for EG to 8.5 mg/L for TEG and from 1.3 mg/L for EG to 18.2 mg/L for 1,2-PD. A linear response was observed over the concentration range from 1 to 800 mg/L for EG and 18 from 800 for TEG and 1,2-PD for serum and blood. Coefficients of variation for both intra-assay precision and interassay reproductibility ranged respectively between 1.9% for TEG to 4.9% for 1,2-PD (11.8% for HXG) and 3.5% for DEG to 9% for 2,3-BD (20.4 for HXG) at the 400 mg/L serum level. The method was applied to plasma and whole blood. PMID:12166815

  11. In Vivo Neurochemical Monitoring using Benzoyl Chloride Derivatization and Liquid ChromatographyMass Spectrometry

    PubMed Central

    Song, Peng; Mabrouk, Omar S.; Hershey, Neil D.; Kennedy, Robert T.

    2011-01-01

    In vivo neurochemical monitoring using microdialysis sampling is important in neuroscience because it allows correlation of neurotransmission with behavior, disease state, and drug concentrations in the intact brain. A significant limitation of current practice is that different assays are utilized for measuring each class of neurotransmitter. We present a high performance liquid chromatography (HPLC) - tandem mass spectrometry method that utilizes benzoyl chloride for determination of the most common low molecular weight neurotransmitters and metabolites. In this method, 17 analytes were separated in 8 minutes. The limit of detection was 0.03–0.2 nM for monoamine neurotransmitters, 0.05–11 nM for monoamine metabolites, 2–250 nM for amino acids, 0.5 nM for acetylcholine, 2 nM for histamine, and 25 nM for adenosine at sample volume of 5 µL. Relative standard deviation for repeated analysis at concentrations expected in vivo averaged 7% (n = 3). Commercially available 13C benzoyl chloride was used to generate isotope-labeled internal standards for improved quantification. To demonstrate utility of the method for study of small brain regions, the GABAA receptor antagonist bicuculline (50 µM) was infused into rat ventral tegmental area while recording neurotransmitter concentration locally and in nucleus accumbens, revealing complex GABAergic control over mesolimbic processes. To demonstrate high temporal resolution monitoring, samples were collected every 60 s while neostigmine, an acetylcholine esterase inhibitor, was infused into the medial prefrontal cortex. This experiment revealed selective positive control of acetylcholine over cortical glutamate. PMID:22118158

  12. CHROMATOGRAPHIC PERSPECTIVE OF HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY

    EPA Science Inventory

    The coupling of high-performance liquid chromatography with mass spectrometry (HPLC-MS) is today a rapidly advancing field. In the paper, the chromatographic aspects of this coupling are reviewed. It is shown that the quantitative evaluation of resulting chromatograms, based on c...

  13. SPECIATION OF SUBSURFACE CONTAMINANTS BY CONE PENETROMETRY GAS CHROMATOGRAPHY/MASS SPECTROMETRY. (R826184)

    EPA Science Inventory

    A thermal extraction cone penetrometry gas chroma tography/mass spectrometry system (TECP GC/MS) has been developed to detect subsurface contaminants in situ. The TECP can collect soil-bound organics up to depths of 30 m. In contrast to traditional cone penetrometer sample collec...

  14. Chapter 3. Determination of semivolatile organic compounds and polycyclic aromatic hydrocarbons in solids by gas chromatography/mass spectrometry

    USGS Publications Warehouse

    Zaugg, Steven D.; Burkhardt, Mark R.; Burbank, Teresa L.; Olson, Mary C.; Iverson, Jana L.; Schroeder, Michael P.

    2006-01-01

    A method for the determination of 38 polycyclic aromatic hydrocarbons (PAHs) and semivolatile organic compounds in solid samples is described. Samples are extracted using a pressurized solvent extraction system. The compounds of interest are extracted from the solid sample twice at 13,800 kilopascals; first at 120 degrees Celsius using a water/isopropyl alcohol mixture (50:50, volume-to-volume ratio), and then the sample is extracted at 200 degrees Celsius using a water/isopropyl alcohol mixture (80:20, volume-to-volume ratio). The compounds are isolated using disposable solid-phase extraction (SPE) cartridges containing divinylbenzene-vinylpyrrolidone copolymer resin. The cartridges are dried with nitrogen gas, and then sorbed compounds are eluted from the SPE material using a dichloromethane/diethyl ether mixture (80:20, volume-to-volume ratio) and passed through a sodium sulfate/Florisil SPE cartridge to remove residual water and to further clean up the extract. The concentrated extract is solvent exchanged into ethyl acetate and the solvent volume reduced to 0.5 milliliter. Internal standard compounds are added prior to analysis by capillary-column gas chromatography/mass spectrometry. Comparisons of PAH data for 28 sediment samples extracted by Soxhlet and the accelerated solvent extraction (ASE) method described in this report produced similar results. Extraction of PAH compounds from standard reference material using this method also compared favorably with Soxhlet extraction. The recoveries of PAHs less than molecular weight 202 (pyrene or fluoranthene) are higher by up to 20 percent using this ASE method, whereas the recoveries of PAHs greater than or equal to molecular weight 202 are equivalent. This ASE method of sample extraction of solids has advantages over conventional Soxhlet extraction by increasing automation of the extraction process, reducing extraction time, and using less solvent. Extract cleanup also is greatly simplified because SPE replaces commonly used gel permeation chromatography. The performance of the method (as expressed by mean recoveries and mean precision) was determined using Ottawa sand, a commercially available topsoil, and an environmental stream sediment, fortified at 1.5 and 15 micrograms per compound. Recoveries of PAH and semivolatile compounds in Ottawa sand samples fortified at 1.5 micrograms averaged 88 percent ? 9.4 percent relative standard deviation, and calculated initial method detection limits per compound averaged 14 micrograms per kilogram, assuming a 25-gram sample size. The recovery for 1,2,4-trichlorobenzene is less than 60 percent; thus, the concentration of this compound will always be reported as estimated with the E remark code. The analysis of 25 alkylated PAH homolog groups also can be determined with this method with extra data analysis and review, but because of the lack of authentic reference standard compounds, these results are considered to be semiquantitative. The PAH homolog groups are quantitated using the response factor of a parent PAH method compound, if available. Precision data for the alkylated PAH homologs detected in a marine sediment standard reference material (SRM 1944) also are presented to document and demonstrate method capability.

  15. Spectral Deconvolution for Gas Chromatography Mass Spectrometry-Based Metabolomics: Current Status and Future Perspectives

    PubMed Central

    Du, Xiuxia; Zeisel, Steven H

    2013-01-01

    Mass spectrometry coupled to gas chromatography (GC-MS) has been widely applied in the field of metabolomics. Success of this application has benefited greatly from computational workflows that process the complex raw mass spectrometry data and extract the qualitative and quantitative information of metabolites. Among the computational algorithms within a workflow, deconvolution is critical since it reconstructs a pure mass spectrum for each component that the mass spectrometer observes. Based on the pure spectrum, the corresponding component can be eventually identified and quantified. Deconvolution is challenging due to the existence of co-elution. In this review, we focus on progress that has been made in the development of deconvolution algorithms and provide thoughts on future developments that will expand the application of GC-MS in metabolomics. PMID:24688694

  16. LC-MSsim - a simulation software for liquid chromatography mass spectrometry data

    Microsoft Academic Search

    Ole Schulz-trieglaff; Nico Pfeifer; Clemens Gröpl; Oliver Kohlbacher; Knut Reinert

    2008-01-01

    Background: Mass Spectrometry coupled to Liquid Chromatography (LC-MS) is commonly used to analyze the protein content of biological samples in large scale studies. The data resulting from an LC-MS experiment is huge, highly complex and noisy. Accordingly, it has sparked new developments in Bioinformatics, especially in the fields of algorithm development, statistics and software engineering. In a quantitative label-free mass

  17. Determination of triazine pesticides and related compounds in environmental water by liquid chromatography-mass spectrometry.

    PubMed

    Tanabe, Akiko; Kawata, Kuniaki

    2004-01-01

    A method for the determination of 5 triazine herbicides and 12 degradation products in environmental water samples using liquid chromatography-electrospray ionization mass spectrometry (LC/ESI/MS) has been developed. The pesticides in water were extracted with two types of solid phase: a styrene-divinylbenzene copolymer and a graphitized carbon black. Desorption solvents for the extracted compounds were acetone for the styrene-divinylbenzene copolymer and methanol for the graphitized carbon black. Overall recoveries from ground water and river water ranged from 73% to 111%. The limits of detection (LODs) were 0.2 to 28 ng l(-1). This method was applied to several ground water samples. PMID:14753289

  18. Investigation of used synthetic lubricants by computerized gas chromatography/mass spectrometry.

    PubMed

    Sturaro, A; Doretti, L; Parvoli, G

    1990-12-01

    The chemical fractions of a used, synthetic lubricating oil for petrol engines were separated by flash chromatography on a silica gel column using variable mixtures of hexane/chloroform as eluents. The products extracted in the most polar fraction were separated by gas chromatography and then analyzed by computerized mass spectrometry. The analytical method used allowed the identification, among the various compounds, of a family of tetrahydropyran homologues with an aminic chain, phthalates, thiophene and pyridine derivatives. The presence of these structures, some of which are of toxicological interest, was also shown by infrared spectra. PMID:2270471

  19. Development of a gas chromatography-mass spectrometry method for the quantification of glucaric Acid derivatives in beverage substrates.

    PubMed

    Craig, Ana Paula; Fields, Christine C; Simpson, John V

    2014-01-01

    A gas chromatography-mass spectrometry (GC-MS) method using the standard addition methodology was developed for the determination of glucuronolactone (GL) and glucuronic acid (DGuA) in four beverages categorized as detoxification, recovery, or energy drinks. The method features a precolumn derivatization step with a combination of BSTFA (N,O-bis(trimethylsilyl)trifluoroacetamide) and TMCS (trimethylchlorosilane) to silylate the analytes. The sample pretreatment required no extraction, filtration, or reduction step prior to the injection. The quantification of the analytes was performed using a five-point standard addition protocol. The proposed method presented excellent intraday precision (%RSD < 10) and linearity for GL calibration curves (correlation coefficients > 0.995) and acceptable linearity for DGuA calibration curves (correlation coefficients > 0.97). The estimated limits of detection (LOD) and quantification (LOQ) for GL ranged from 0.006?ppm to 0.14?ppm, and 0.02?ppm to 0.47?ppm, respectively. The estimated LOD and LOQ for DGuA determination ranged, respectively, from 0.06?ppm to 1.1?ppm and 0.2?ppm to 3.8?ppm. The results demonstrated that the method should be regarded as a reliable alternative to the simultaneous determination of GL and DGuA. PMID:25024704

  20. Detection of 3-nitrotyrosine in human platelets exposed to peroxynitrite by a new gas chromatography/mass spectrometry assay.

    PubMed

    Jiang, H; Balazy, M

    1998-01-01

    A new sensitive and specific assay was developed and applied for the quantitative determination of 3-nitrotyrosine in proteins of human platelets. 3-Nitrotyrosine was quantitatively converted into a new pentafluorobenzyl derivative in a single step and detected as an abundant carboxylate anion at m/z 595 using negative ion chemical ionization gas chromatography/mass spectrometry. The internal standard, [13C6]-3-nitrotyrosine, was prepared via a new and efficient method using nitronium borofluorate dissolved in hydrochloric acid. The assay showed excellent linearity and sensitivity. Intact human platelets contained 1.4+/-0.6 ng of 3-nitrotyrosine per milligram of protein. Peroxynitrite increased 3-nitrotyrosine levels 4- to 535-fold at the concentration range of 10 to 300 microM. Decomposed peroxynitrite was without the effect. Nitrogen dioxide (43 microM) was also a potent tyrosine nitrating molecule, increasing the levels of 3-nitrotyrosine 153-fold. HOCl (50 microM) in the presence of nitrite (50 microM) increased the 3-nitrotyrosine levels 3-fold. Exposure of platelets to nitric oxide, nitrite, thrombin, adenosine diphosphate, platelet activating factor, and arachidonic acid had no effect on platelet 3-nitrotyrosine levels. PMID:10100490

  1. Determination of thiodiglycol, a mustard gas hydrolysis product by gas chromatography-mass spectrometry after tert-butyldimethylsilylation.

    PubMed

    Ohsawa, Isaac; Kanamori-Kataoka, Mieko; Tsuge, Kouichiro; Seto, Yasuo

    2004-12-24

    A method for determining thiodiglycol (TDG), a mustard gas hydrolysis product in water, serum and urine samples using gas chromatography-mass spectrometry (GC-MS) after tert-butyldimethylsilylation (TBDMS) is described. Quantitation of TDG was performed by measuring the respective peak area on the extracted ion chromatogram of m/z 293, using an internal standard, the TDG homologue, thiodipropanol, peak area of which was measured as m/z 321. The presence of salts in the sample solution not only suppressed the loss of TDG by vaporization during the evaporation of water, but also facilitated the rate of production of di-silylated derivative, bis(tert-butyldimethylsilyoxylethyl)sulfide (TDG-(TBDMS)2). Under the pretreatment conditions used, in which 0.5 ml of water sample supplemented with 100 microM potassium chloride was evaporated to dryness under reduced pressure, followed by reaction with N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide at 60 degrees C for 1 h, TDG-(TBDMS)2 was reproducibly detected with about a 55% recovery and a limit of detection (LOD, scan mode, S/N = 3) of 5.4 ng/ml. TDG was also determined by GC-MS from a 0.5 ml serum sample (after perchloric acid deproteinization) and from a 0.1 ml urine sample, after TBDMS derivatization. The LOD was determined to be 7.0 and 110 ng/ml for serum and urine, respectively. PMID:15641367

  2. Multiplexed dual first-dimension comprehensive two-dimensional gas chromatography-mass spectrometry with contra-directional thermal modulation.

    PubMed

    Savareear, Benjamin; Jacobs, Matthew R; Shellie, Robert A

    2014-10-24

    A multiplexed dual-primary column comprehensive two-dimensional gas chromatography-mass spectrometry approach (2GC×GC-MS) is introduced. The approach splits injected samples into two first-dimension columns with different stationary phases, and recombines the two streams into one second-dimension column that terminates at a single detector. The approach produces two two-dimensional chromatograms for each injection, and is made possible by using a dual-stage modulator operated in contra-directional modulation mode. The dual two-dimensional chromatograms produced by this single detector system provide complementary information due to selectivity differences between the three separation columns used in the column ensemble. An aged Australian tea tree (Melaleuca alternifolia) essential oil was analyzed to demonstrate the 2GC×GC-MS approach. The number of compounds separated by each of the GC×GC separations in the 2GC×GC experiment is comparable to conventional GC×GC experiments with matching column configurations. Robust peak assignment was possible for this sample based on the combination of MS library matches and multiple linear retention index searching. Forty-nine components (22 unique) were identified using a non-polar×mid-polar column combination and 34 components (7 unique) were positively identified using a polar×mid-polar column combination. Twenty-seven peak assignments were corroborated by positive identification in both of the multiplexed separations. PMID:25249490

  3. Identification and Quantification of Several Contaminated Compounds in Replacement Liquids of Electronic Cigarettes by Gas Chromatography-Mass Spectrometry.

    PubMed

    Oh, Jin-Aa; Shin, Ho-Sang

    2015-07-01

    Electronic cigarettes (E-cigarettes) are devices that are refilled with replacement liquids, which normally contain propylene glycol, nicotine and the desired flavor blend. Many consumers suspect that hazardous substances are present in addition to nicotine content. In this study, eight contaminated compounds in 105 replacement liquids from 11 types of E-cigarettes sold in the Republic of Korea were identified and quantified by gas chromatography-mass spectrometry. Diethyl phthalate and diethylhexyl phthalate were detected in concentration ranges of 0.01-1745.20 mg/L (47.6% detection frequency) and 0.06-81.89 mg/L (79.1% detection frequency) in the replacement liquids. Triethylene glycol, tetraethylene glycol and pentaethylene glycol were quantified in concentration ranges of 0.1-19.3 mg/L (10.5% detection frequency), 0.1-30.1 mg/L (12.4% detection frequency) and 0.1-24.9 mg/L (6.7% detection frequency) in the same samples. cis-3-Hexene-1-ol, methyl cinnamate and dodecane were quantified in concentration ranges of 0.03-3267.46 mg/L (70.5% detection frequency), 4.41-637.54 mg/L (6.7% detection frequency) and 0.01-639.96 mg/L (47.6% detection frequency) in the samples. PMID:25404560

  4. A liquid chromatography-mass spectrometry-based approach to characterize the substrate specificity of mammalian heparanase.

    PubMed

    Mao, Yang; Huang, Yu; Buczek-Thomas, Jo Ann; Ethen, Cheryl M; Nugent, Matthew A; Wu, Zhengliang L; Zaia, Joseph

    2014-12-01

    Extracellular heparanase activity releases growth factors and angiogenic factors from heparan sulfate (HS) storage sites and alters the integrity of the extracellular matrix. These activities lead to a loss of normal cell matrix adherent junctions and correlate with invasive cellular phenotypes. Elevated expression of heparanase is associated with several human cancers and with vascular remodeling. Heparanase cleaves only a limited fraction of glucuronidic linkages in HS. There have been few investigations of the functional consequences of heparanase activity, largely due to the heterogeneity and complexity of HS. Here, we report a liquid chromatography-mass spectrometry (LC-MS)-based approach to profile the terminal structures created by heparanase digestion and reconstruct the heparanase cleavage sites from the products. Using this method, we demonstrate that heparanase cleaves at the non-reducing side of highly sulfated HS domains, exposing cryptic growth factor binding sites. This cleavage pattern is observed in HS from several tissue sources, regardless of overall sulfation degree, indicating a common recognition pattern. We further demonstrate that heparanase cleavage of HS chains leads to increased ability to support FGF2-dependent cell proliferation. These results suggest a new mechanism to explain how heparanase might potentiate the uncontrolled cell proliferation associated with cancer through its ability to activate nascent growth factor-promoting domains within HS. PMID:25336655

  5. Assay of physiological levels of 2,3-butanediol diastereomers in blood and urine by gas chromatography-mass spectrometry.

    PubMed

    Montgomery, J A; Jetté, M; Brunengraber, H

    1990-02-15

    We present an assay for 2,3-butanediol by gas chromatography-mass spectrometry of its trimethylsilyl ethers. 2R,3R- and/or 2S,3S-2,3-butanediol and meso-2,3-butanediol are quantitated with corresponding internal standards of [2,3-2H2]butanediol. Limits of detection are 1 and 0.1 microM for split and splitless injections, respectively. Blood concentrations of 2,3-butanediol in nonalcoholics are 0.5 +/- 0.3 (SD) microM for 2R,3R- and/or 2S,3S-2,3-butanediol and 0.8 +/- 0.4 microM for meso-2,3-butanediol (n = 9). Two hours after alcohol ingestion, blood levels had risen in eight of nine subjects to 1.2 +/- 0.7 microM for 2R,3R-/2S,3S-2,3-butanediol and to 1.2 +/- 0.6 microM for meso-2,3-butanediol. Baseline urinary excretion of 2,3-butanediol is 0.4 +/- 0.2 mumol/mmol creatinine for 2R,3R-/2S,3S-2,3-butanediol and 0.9 +/- 0.5 mumol/mmol creatinine for meso-2,3-butanediol. PMID:2344048

  6. Characterization of organic fouling in reverse osmosis membranes by headspace solid phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Martínez, C; Gómez, V; Pocurull, E; Borrull, F

    2015-01-01

    Adsorption of organic substances on reverse osmosis (RO) membrane surfaces may form an organic film on the membrane, known as organic fouling, and cause flow-rate loss. This problem is mostly unavoidable as no pretreatment method exists for perfect removal of possible foulants, including organic compounds resulting from undesirable bioactivity. Understanding the characteristics of fouling layers is an essential step towards overall improvement of RO membrane operations. In this study, the organic fouling in RO membranes treating the effluent of a secondary treatment from an urban wastewater treatment plant was characterized. Headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry has been used for the first time, to provide valuable information of organic fouling. Different polarity SPME fibers were tested for this purpose. In addition, the characterization of the organic fouling obtained by HS-SPME was compared with the results obtained by extraction using several organic solvents. The results indicated that more compound families can be identified by HS-SPME than by organic solvent extraction. Moreover, complementary organic analyses were done for better understanding of the organic fouling in RO membranes, such as total organic carbon and loss on ignition. PMID:25607678

  7. Liquid chromatography mass spectrometry simultaneous determination of vindoline and catharanthine in rat plasma and its application to a pharmacokinetic study.

    PubMed

    Lin, Chongliang; Cai, Jinzhang; Yang, Xuezhi; Hu, Lufeng; Lin, Guanyang

    2015-01-01

    Vinblastine and vincristine, both of which are bisindole alkaloids derived from vindoline and catharanthine, have been used for cancer chemotherapy; their monomeric precursor molecules are vindoline and catharanthine. A simple and selective liquid chromatography mass spectrometry method for simultaneous determination of vindoline and catharanthine in rat plasma was developed. Chromatographic separation was achieved on a C18 (2.1?×?50?mm, 3.5?µm) column with acetonitrile-0.1% formic acid in water as mobile phase with gradient elution. The flow rate was set at 0.4?mL/min. An electrospray ionization source was applied and operated in positive ion mode; selective ion monitoring mode was used for quantification. Mean recoveries were in the range of 87.3-92.6% for vindoline in rat plasma and 88.5-96.5% for catharanthine. Matrix effects for vindoline and catharanthine were measured to be between 95.3 and 104.7%. Coefficients of variation of intra-day and inter-day precision were both <15%. The accuracy of the method ranged from 93.8 to 108.1%. The method was successfully applied in a pharmacokinetic study of vindoline and catharanthine in rats. The bioavailability of vindoline and catharanthine were 5.4 and 4.7%, respectively. PMID:24828449

  8. Sensitive and rapid method to quantify icaritin and desmethylicaritin in human serum using gas chromatography-mass spectrometry.

    PubMed

    Shen, Ping; Wong, Shih Peng; Yong, E L

    2007-09-15

    The prenyl-flavones, icaritin and desmethylicaritin, are bioactive compounds from the traditional Chinese medicinal herb, Epimedium, extracts of which can enhance bone health in animal models. In order to examine their bioavailability in humans, we have developed and validated a sensitive method to quantify icaritin and desmethylicaritin in human sera, using gas chromatography-mass spectrometry. The serum samples were extracted with ethyl acetate and then derivatized with BSTFA in pyridine (4:1). With genistein as internal standard, calibration curves with good linearity (R(2)>0.99) within the concentration range of 0.15-10nM in the selective ion monitoring mode were obtained. The limits of detection and quantization were 11 and 33 pM for icaritin, and 23 and 70 pM for desmethylicaritin, respectively; inter- and intra-assay variabilities were <15%, and accuracies were between 89 and 110%. Icaritin, but not desmethylicaritin, was detected from 1h, increasing to a peak at 8h (1.51+/-1.6 nM) in sera of human volunteers after ingestion of an aqueous decoction of Epimedium. This sensitive method can be used to quantify serum levels of icaritin and desmethylicaritin for pharmacokinetic studies. PMID:17632044

  9. Microwave assisted extraction for the determination of ethyl glucuronide in urine by gas chromatography-mass spectrometry.

    PubMed

    Freire, Iván Alvarez; Barrera, Ana María Bermejo; Silva, Purificación Cid; Duque, María Jesús Tabernero; Gómez, Purificación Fernández; Eijo, Patricia López

    2008-08-01

    Alcohol is the most frequently abused 'addictive substance' that causes serious social problems throughout the world; thus alcoholism is of particular interest in clinical and forensic medicine. Ethyl glucuronide (EtG) is a marker of recent alcohol consumption that detects alcohol use reliably over a definite time period. The present paper describes a new method for the determination of EtG in urine. It was based both on microwave assisted extraction (MAE) to extract the analyte from urine samples, and gas chromatography-mass spectrometry (GC-MS) to identify and quantify the EtG in selected ion monitoring (SIM) mode. The method was applied to 33 urine samples from alcohol users, obtaining positive results in all cases. It was fully validated including a linear range (0.1-100 microg ml(-1)) and the main precision parameters. In summary, the use of microwave assisted extraction turned out to be a substantially simpler, faster and more sensitive procedure than any other conventional sample preparations. PMID:18344200

  10. Fundamental studies with a monodisperse aerosol-based liquid chromatography/mass spectrometry interface (MAGIC-LC/MS)

    SciTech Connect

    Browner, R.F.

    1990-10-01

    Accomplishments on the fundamental studies with a monodisperse aerosol-based liquid chromatography/mass spectrometry (LC/MS) interface during the period 1 December 1989 to 30 November 1990 are summarized. In order to determine the influence of temperature on the vaporization and decomposition properties of molecules, test have been carried out on both thermally stable and thermally labile molecules. The test compounds used were a series of polynuclear aromatic (PAH) compounds covering a wide range of molecular weights from two-ring naphthalene to twelve-ring perylene. The less thermally stable species examined were aldicarb, a highly thermally labile pesticide, and cholesterol, which readily loses water when subjected to high temperatures. A new, externally heated probe, which can be raised to temperatures as high as 500{degree}C was also used. Matrix loading effects for a range of surface active and non-surface active compounds in three different matrices: glycerol, 3-nitrobenzyl alcohol, and thioglycerol for fast atom bombardment (FAB) particle beam LC/MS have been studied. The time dependence of FAB spectra generation in the particle beam system has been examined and contrasted with ion generation in normal probe FAB work. Future FAB LC/MS research is outlined. 3 refs. (BM)

  11. Histochemical evaluation of alkaloids in rhizome of Coptis chinensis using laser microdissection and liquid chromatography/mass spectrometry.

    PubMed

    Yi, Ling; Liang, Zhi-Tao; Peng, Yong; Guo, Ping; Wong, Lai-Lai; Wan, Xiao-Jing; Ho, Hing-Man; Yi, Tao; Zhao, Zhong-Zhen

    2015-06-01

    Traditional macroscopic and microscopic identification methods of medicinal materials are economical and practical, but usually experience-based due to few chemical supports. Here histochemical evaluation on bioactive components of Coptidis Rhizoma (CR) in anatomic sections using laser microdissection and liquid chromatography-mass spectrometry (LMD-LC-MS) was developed to correlate the inner quality and outer features of materials from different growing areas. Results of a total 33 peaks representing potential different alkaloids were detected and 8 common peaks were identified as the major alkaloids, namely magnoflorine, thalifendine, columbamine, epiberberine, jatrorrhizine, coptisine, palmatine, and berberine. Six major alkaloids were quantified in the top and middle sections of raw materials and in their tissues and cells at the same time. Histochemical analyses showed consistent results with direct determination in raw materials and explained the reason why top sections of all samples contained higher contents of alkaloids by giving out attributions of each alkaloid in different anatomic sections. Besides, results manifested the distribution and accumulation rules of alkaloids in diverse tissues and cells of CR. This study demonstrates an effective and scientific way to correlate bioactive components and morphological features of medicinal materials, which is beneficial to future research, agriculture and application. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25209714

  12. [Simultaneous determination of melamine and creatinine in milk and milk products by gas chromatography-mass spectrometry].

    PubMed

    Zeng, Kai; Liu, Zhirong; Ning, Yajun; Li, Jinlin; Tang, Jun; Zhang, Min

    2013-05-01

    A method established for determining melamine and creatinine in milk and milk products. The samples were extracted with 1% trichloracetic acid solution. The extract was cleaned-up by using a mixed-mode cation ion exchange SPE column and evaporated to dryness under nitrogen. The residue was derived by bis (trimethylsilyl) trifluoroacetamide-chlorotrimethylsilane (BSTFA-TMCS), then determined by gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode. Melamine and creatinine had good linearity in the range of 0.1 - 50 mg/L with the correlation coefficients higher than 0.99, and the limits of quantification were 0.10 mg/kg and 0.20 mg/kg, respectively. The recoveries of melamine and creatinine were 80.7% - 116.8% and 77.6% - 107.5% with RSD no more than 9.4% and 8.5% in the spiked range of 10 - 100 mg/kg and 0.1 - 5.0 mg/kg, respectively. The method is accurate, sensitive, and suitable for the determination of creatinine in milk and milk products. PMID:24010350

  13. [Determination of gomisin A (TJN-101) and its metabolite in rat serum by gas chromatography-mass spectrometry].

    PubMed

    Matsuzaki, Y; Ishibashi, E; Koguchi, S; Wakui, Y; Takeda, S; Aburada, M; Oyama, T

    1991-10-01

    Gomisin A (TJN-101) is one of the lignan components isolated from Schisandra Fruits. A high sensitive and precise method for the determination of TJN-101 and its major metabolite (Met. B) in the rat serum was developed by selected ion monitoring (SIM) with gas chromatography-mass spectrometry (GC/MS) using a fused silica capillary column (SPB-1, Supelco). A 100 microliter serum sample was used for the solid phase extraction. The calibration curves of TJN-101 and Met.B both showed a good linearity between 2.0 and 2000.0 ng/ml. The analytical precision (intra-assay, C.V. less than 4.7%), recoveries (98.4 +/- 10.1%), and detection limit (2 ng/ml) of TJN-101 indicated that this system was suited for the determination of TJN-101 in biological fluid. In case of Met.B, the same results as TJN-101, were obtained. After oral administration of TJN-101 at a dose of 10 mg/kg to male rats, the average values of the maximal serum concentration of TJN-101 and Met.B were 1446.1 +/- 131.8 and 317.4 +/- 18.5 ng/ml, respectively. The serum concentrations of these substances could be monitored sufficiently for 8 h after dosing. PMID:1812283

  14. Novel ethyl-derivatization approach for the determination of fluoride by headspace gas chromatography/mass spectrometry.

    PubMed

    Pagliano, Enea; Meija, Juris; Ding, Jianfu; Sturgeon, Ralph E; D'Ulivo, Alessandro; Mester, Zoltán

    2013-01-15

    We report a novel derivatization chemistry for determination of fluoride based on the batch reaction of fluoride ions with triethyloxonium tetrachloroferrate(III) in a closed vessel to yield fluoroethane. Gaseous fluoroethane was readily separated from the matrix, sampled from the headspace, and determined by gas chromatography/mass spectrometry. The method was validated using rainwater certified reference material (IRMM CA408) and subsequently applied to the determination of fluoride in various matrixes, including tap water, seawater, and urine. An instrumental limit of detection of 3.2 ?g/L with a linear range up to 50 mg/L was achieved. The proposed derivatization is a one-step reaction, requires no organic solvents, and is safe, as the derivatizing agent is nonvolatile. Determination of fluoride is affected by common fluoride-complexing agents, such as Al(III) and Fe(III). The effect of large amounts of these interferences was studied, and the adverse effect of these ions was eliminated by use of the method of standard additions. PMID:23215254

  15. Development of gas chromatography/mass spectrometry following headspace solid-phase microextraction for fast determination of asarones in plasma.

    PubMed

    Deng, Chunhui; Lin, Shuang; Huang, Taoming; Duan, Gengli; Zhang, Xiangmin

    2006-01-01

    Asarones (alpha-asarone and beta-asarone) are the active components in the traditional Chinese medicine (TCM) of Acorus tatarinowii Schott, which has been used to treat epilepsy for several thousand years. To perform the pharmacokinetics (PK) study of alpha- and beta-asarone from the TCM essential oil, a simple, rapid and sensitive method was developed for the determination of asarones from the TCM in rabbit plasma, based on headspace solid-phase microextraction (HS-SPME) followed by gas chromatography/mass spectrometry (GC/MS) with electron ionization (EI). The extraction parameters of headspace volume, fiber coating, sample temperature, extraction time, stirring rate and ion strength were systemically optimized. Furthermore, the method linearity, detection limit and precision were also investigated. It was shown that the proposed method provided a good linearity (0.02-20 microg/mL, R(2) > 0.99), low detection limit (<2.0 ng/mL) and good precision (RSD < 7.0%). Finally, HS-SPME followed by GC/MS was applied to fast determination of alpha- and beta-asarone in rabbit plasma at different time points after oral adminstration of the essential oil from A. tatarinowii. The experimental results suggest that the proposed method provides an alternative approach to the PK studies of volatile compounds in TCMs. PMID:16773672

  16. Determination of aromatic hydrocarbons in bituminous emulsion sealants using headspace solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Tang, Bing; Isacsson, Ulf

    2006-12-22

    The possibility of quantitative determination of aromatic hydrocarbons in bituminous emulsion sealants was investigated using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS). The target analytes studied were benzene, toluene, ethylbenzene, p-, m-, and o-xylene (BTEX) as well as 1,3,5- and 1,2,4-trimethylbenzene. Experimental factors influencing HS-SPME efficiency were studied (sample-headspace equilibration time, extraction time and sample matrix effects). A HS-SPME method using surrogate matrix was developed. The detection limit was estimated as approximately 0.1 ppmw for the target analytes investigated. Good linearity was observed (R(2)>0.997) for all calibration curves obtained. The repeatability of the method (RSD, relative standard deviation) was found less than 10%. The accuracy of the method given by recovery of spiked samples was between 99 and 116%. The HS-SPME method developed was applied to two commercially available bituminous emulsion sealants. External calibration and standard addition approaches were investigated, and statistical paired t-test was performed. The contents of target aromatic hydrocarbons in the sealants studied varied from approximately 0.4 to 150 ppmw. The method developed shows potential as a tool for the determination of aromatic hydrocarbons in emulsified bituminous materials. PMID:17069821

  17. Nanoscale reversed-phase liquid chromatography-mass spectrometry of permethylated N-glycans.

    PubMed

    Ritamo, Ilja; Räbinä, Jarkko; Natunen, Suvi; Valmu, Leena

    2013-03-01

    Reversed-phase liquid chromatography on the nanoscale coupled to electrospray tandem mass spectrometry was used to analyse a mixture of four commercial glycan standards, and the method was further adapted to N-glycans enzymatically released from alpha-1-acid glycoprotein and immunoglobulin gamma. Glycans were permethylated to enable their separation by reversed-phase chromatography and to facilitate interpretation of fragmentation data. Prior to derivatization of glycans by permethylation, they were reduced to cancel anomerism because, although feasible, it was not desired to separate ?- and ?-anomers. The effect of supplementing chromatographic solvent with sodium hydroxide to guide adduct formation was investigated. Raising the temperature in which the separation was performed improved chromatographic resolution and affected retention times as expected. It was shown by using the tetrasaccharides sialyl Lewis X and sialyl Lewis A that reversed-phase chromatography could achieve the separation of methylated isobaric glycan analytes. Isobaric glycans were detected among the N-glycans of immunoglobulin gamma and further analysed by tandem mass spectrometry. PMID:23307132

  18. GC/MS (GAS CHROMATOGRAPHY-MASS SPECTROMETRY) ANALYSIS OF ORGANICS IN DRINKING WATER CONCENTRATES AND ADVANCED WASTE TREATMENT CONCENTRATES. VOLUME 2. COMPUTER-PRINTED TABULATIONS OF COMPOUND IDENTIFICATION RESULTS FOR LARGE-VOLUME CONCENTRATES

    EPA Science Inventory

    This volume presents the complete set of computer-printed tables for the compound identification results on the concentrates produced from large volumes of drinking water (DW) and advanced waste treatment (AWT) water. All discussion of the DW and AWT analysis results appears in V...

  19. Analysis of fatty acid ethyl esters in hair as possible markers of chronically elevated alcohol consumption by headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS)

    Microsoft Academic Search

    F. Pragst; V. Auwaerter; F. Sporkert; K. Spiegel

    2001-01-01

    Fatty acid ethyl esters (FAEE) are products of the nonoxidative ethanol metabolism, which are known to be detectable in blood only about 24h after the last alcohol intake. After deposition in hair they should be suitable long-term markers of chronically elevated alcohol consumption. Therefore, a method for the analysis of ethyl myristate, ethyl palmitate, ethyl oleate and ethyl stearate from

  20. Improved methods for urinary atrazine mercapturate analysis—Assessment of an enzyme-linked immunosorbent assay (ELISA) and a novel liquid chromatography–mass spectrometry (LC–MS) method utilizing online solid phase extraction (SPE)

    Microsoft Academic Search

    Marja E. Koivunen; Katja Dettmer; Roel Vermeulen; Berit Bakke; Shirley J. Gee; Bruce D. Hammock

    2006-01-01

    Elimination of interfering substances in urine by solid phase extraction (SPE) prior to analysis resulted in 10-fold improvement in the sensitivity of atrazine mercapturate (AM) enzyme-linked immunosorbent assay (ELISA) compared to previous reports. Of the two tested SPE systems, Oasis® HLB and MCX, the mixed-mode MCX gave good recoveries (82%) of AM in spiked samples measured by ELISA, whereas the

  1. Sol-gel hybrid methyltrimethoxysilane-tetraethoxysilane as a new dispersive solid-phase extraction material for acrylamide determination in food with direct gas chromatography-mass spectrometry analysis.

    PubMed

    Omar, Mei Musa Ali; Wan Ibrahim, Wan Aini; Elbashir, Abdalla Ahmed

    2014-09-01

    A sol-gel hybrid sorbent, methyltrimethoxysilane-tetraethoxysilane (MTMOS-TEOS) was successfully used as new dispersive solid phase extraction (dSPE) sorbent material in the determination of acrylamide in several Sudanese foods and analysis using GC-MS. Several important dSPE parameters were optimised. Under the optimised conditions, excellent linearity (r(2)>0.9998) was achieved using matrix matched standard calibration in the concentration range 50-1000 ?g kg(-1). The limits of detection (LOD) and limit of quantification ranged from 9.1 to 12.8 ?g/kg and 27.8-38.9 ?g/kg, respectively. The precision (RSD%) of the method was ?6.6% and recoveries of acrylamide obtained were in the range of 88-103%, (n=3). The LOD obtained is comparable with the LODs of primary secondary amine dSPE. The proposed MTMOS-TEOS dSPE method is direct and safe for acrylamide analysis, showed reliable method validation performances and good cleanup effects. It was successfully applied to the analysis of acrylamide in real food samples. PMID:24731346

  2. Simultaneous and high-throughput analysis of iodo-trihalomethanes, haloacetonitriles, and halonitromethanes in drinking water using solid-phase microextraction/gas chromatography-mass spectrometry: an optimization of sample preparation.

    PubMed

    Luo, Qian; Chen, Xichao; Wei, Zi; Xu, Xiong; Wang, Donghong; Wang, Zijian

    2014-10-24

    When iodide and natural organic matter are present in raw water, the formation of iodo-trihalomethanes (Iodo-THMs), haloacetonitriles (HANs), and halonitromethanes (HNMs) pose a potential health risk because they have been reported to be more toxic than their brominated or chlorinated analogs. In the work, simultaneous analysis of Iodo-THMs, HANs, and HNMs in drinking water samples in a single cleanup and chromatographic analysis was proposed. The DVB/CAR/PDMS fiber was found to be the most suitable for all target compounds, although 75?m CAR/PDMS was better for chlorinated HANs and 65?m PDMS/DVB for brominated HNMs. After optimization of the SPME parameters (DVB/CAR/PDMS fiber, extraction time of 30min at 40°C, addition of 40% w/v of salt, (NH4)2SO4 as a quenching agent, and desorption time of 3min at 170°C), detection limits ranged from 1 to 50ng/L for different analogs, with a linear range of at least two orders of magnitude. Good recoveries (78.6-104.7%) were obtained for spiked samples of a wide range of treated drinking waters, demonstrating that the method is applicable for analysis of real drinking water samples. Matrix effects were negligible for the treated water samples with total organic carbon concentration of less than 2.9mg/L. An effective survey conducted by two drinking water treatment plants showed the highest proportion of Iodo-THMs, HANs, and HNMs occurred in treated water, and concentrations of 13 detected compounds ranged between the ng/L and the ?g/L levels. PMID:25257930

  3. Absolute quantification of peptides by isotope dilution liquid chromatography-inductively coupled plasma mass spectrometry and gas chromatography/mass spectrometry.

    PubMed

    Liu, Rui; Hou, Xiandeng; Lv, Yi; McCooeye, Margaret; Yang, Lu; Mester, Zoltán

    2013-04-16

    Absolute quantitation of peptides/proteins in dilute calibration solutions used in various diagnostic settings is a major challenge. Here we report the absolute quantitation of peptides by non-species-specific isotope dilution liquid chromatography-inductively coupled plasma mass spectrometry (ID LC-ICPMS) based on stoichiometric Eu tagging. The method was validated by species-specific isotope dilution gas chromatography/mass spectrometry (GC/MS) analysis of constituent amino acids of the target peptide. Quantitative labeling of bradykinin peptide was accomplished with a commercially available 2',2?-(10-(2-((2,5-dioxopyrrolidin-1-yl)oxy)-2-oxoethyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl) triacetic acid (DOTA-NHS-ester) and subsequently tagged with Eu. A (151)Eu-enriched spike was used for the non-species-specific ID LC-ICPMS determination of bradykinin. The non-species-specific ID LC-ICPMS method was cross-validated by a species-specific ID GC/MS approach, which is based on the determination of phenylalanine in bradykinin to derive the concentration of the peptide in the sample. The hydrolysis of the peptide into amino acids was achieved by microwave digestion with 4 M methanesulfonic acid, and derivatization of phenylalanine with methyl chloroformate (MCF) was performed prior to its detection by GC/MS based on a (13)C-enriched phenylalanine spike. The accuracy of the method was confirmed at various concentration levels with a typical precision of better than 5% relative standard deviation (RSD) at 20 pmol for non-species-specific ID LC-ICPMS and 500 pmol for species-specific ID GC/MS. A detection limit (3 SD) of 7.2 fmol estimated for ID LC-ICPMS with a 10 ?L injection volume from three procedure blanks was obtained for bradykinin, confirming the suitability of the method for the direct determination of peptides at trace levels. To the best of our knowledge, the proposed method is the first ICPMS peptide quantification strategy which employs an independent validation strategy using species-specific ID GC/MS for amino acid quantitation. PMID:23489086

  4. Validation and uncertainty analysis of a multiresidue method for 67 pesticides in made tea, tea infusion, and spent leaves using ethyl acetate extraction and gas chromatography/mass spectrometry.

    PubMed

    Kanrar, Bappaditya; Mandal, Sudeb; Bhattacharyya, Anjan

    2010-01-01

    A rapid, specific, and sensitive multiresidue method to determine 67 pesticides in made tea, tea infusion, and spent leaves was developed and validated for routine analysis by GC/MS with an approximately 29 min GC run time. The method was reproducible (HorRat < 0.5 at 50 ng/g) when validated at 50 and 100 ng/g. The samples were extracted with ethyl acetate-cyclohexane (9 + 1, v/v), and the extracts were cleaned up by dispersive SPE with primary-secondary amine sorbent + graphitized carbon black + Florisil. The recoveries of all the pesticides were within 70-120% with an RSD of < 20% at 50 ng/g and R2 > 0.99. The matrix effect on the signals of the compounds was corrected by using matrix-matched calibration standards. The LOQ met the requirements of the maximum residue limits for pesticides in tea as recommended by the European Union. PMID:20480885

  5. Liquid chromatography-mass spectrometry coupled with multivariate analysis for the characterization and discrimination of extractable and nonextractable polyphenols and glucosinolates from red cabbage and Brussels sprout waste streams.

    PubMed

    Gonzales, Gerard Bryan; Raes, Katleen; Vanhoutte, Hanne; Coelus, Sofie; Smagghe, Guy; Van Camp, John

    2015-07-10

    Nonextractable polyphenol (NEP) fractions are usually ignored because conventional extraction methods do not release them from the plant matrix. In this study, we optimized the conditions for sonicated alkaline hydrolysis to the residues left after conventional polyphenol extraction of Brussels sprouts top (80°C, 4M NaOH, 30min) and stalks (60°C, 4M NaOH, 30min), and red cabbage waste streams (80°C, 4M NaOH, 45min) to release and characterize the NEP fraction. The NEP fractions of Brussels sprouts top (4.8±1.2mg gallic acid equivalents [GAE]/g dry waste) and stalks (3.3±0.2mg GAE/g dry waste), and red cabbage (11.5mg GAE/g dry waste) waste have significantly higher total polyphenol contents compared to their respective extractable polyphenol (EP) fractions (1.5±0.0, 2.0±0.0 and 3.7±0.0mg GAE/g dry waste, respectively). An LC-MS method combined with principal components analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) was used to tentatively identify and discriminate the polyphenol and glucosinolate composition of the EP and NEP fractions. Results revealed that phenolic profiles of the EP and NEP fractions are different and some compounds are only found in either fraction in all of the plant matrices. This suggests the need to account both fractions when analyzing the polyphenol and glucosinolate profiles of plant matrices to attain a global view of their composition. This is the first report on the discrimination of the phenolic and glucosinolate profiles of the EP and NEP fractions using metabolomics techniques. PMID:26008597

  6. Multi-contaminant analysis of organophosphate and halogenated flame retardants in food matrices using ultrasonication and vacuum assisted extraction, multi-stage cleanup and gas chromatography-mass spectrometry.

    PubMed

    Xu, Fuchao; García-Bermejo, Ángel; Malarvannan, Govindan; Gómara, Belén; Neels, Hugo; Covaci, Adrian

    2015-07-01

    A multi-residue analytical method was developed for the determination of a range of flame retardants (FRs), including polybrominated diphenyl ethers (PBDEs), emerging halogenated FRs (EFRs) and organophosphate FRs (PFRs), in food matrices. An ultrasonication and vacuum assisted extraction (UVAE), followed by a multi-stage clean-up procedure, enabled the removal of up to 1g of lipid from 2.5g of freeze-dried food samples and significantly reduce matrix effects. UVAE achieves a waste factor (WF) of about 10%, while the WFs of classical QuEChERS methods range usually between 50 and 90%. The low WF of UVAE leads to a dramatic improvement in the sensitivity along with saving up to 90% of spiking (internal) standards. Moreover, a two-stage clean-up on Florisil and aminopropyl silica was introduced after UVAE, for an efficient removal of pigments and residual lipids, which led to cleaner extracts than normally achieved by dispersive solid phase extraction (d-SPE). In this way, the extracts could be concentrated to low volumes, e.g. <100?L and the equivalent matrix concentrations were up to 100g ww/mL. The final analysis of PFRs was performed on GC-EI-MS, while PBDEs and EFRs were measured by GC-ECNI-MS. Validation tests were performed with three food matrices (lean beef, whole chicken egg and salmon filet), obtaining acceptable recoveries (66-135%) with good repeatability (RSD 1-24%, mean 7%). Method LOQs ranged between 0.008 and 0.04ng/g dw for PBDEs, between 0.08 and 0.20ng/g dw for EFRs, and between 1.4 and 3.6ng/g dw for PFRs. The method was further applied to eight types of food samples (including meat, eggs, fish, and seafood) with lipid contents ranging from 0.1 to 22%. Various FRs were detected above MLOQ levels, demonstrating the wide-range applicability of our method. To the best of our knowledge, this is the first method reported for simultaneous analysis of brominated and organophosphate FRs in food matrices. PMID:25997844

  7. Critical evaluation of methodology commonly used in sample collection, storage and preparation for the analysis of pharmaceuticals and illicit drugs in surface water and wastewater by solid phase extraction and liquid chromatography-mass spectrometry.

    PubMed

    Baker, David R; Kasprzyk-Hordern, Barbara

    2011-11-01

    The main aim of this manuscript is to provide a comprehensive and critical verification of methodology commonly used for sample collection, storage and preparation in studies concerning the analysis of pharmaceuticals and illicit drugs in aqueous environmental samples with the usage of SPE-LC/MS techniques. This manuscript reports the results of investigations into several sample preparation parameters that to the authors' knowledge have not been reported or have received very little attention. This includes: (i) effect of evaporation temperature and (ii) solvent with regards to solid phase extraction (SPE) extracts; (iii) effect of silanising glassware; (iv) recovery of analytes during vacuum filtration through glass fibre filters and (v) pre LC-MS filter membranes. All of these parameters are vital to develop efficient and reliable extraction techniques; an essential factor given that target drug residues are often present in the aqueous environment at ng L(-1) levels. Presented is also the first comprehensive review of the stability of illicit drugs and pharmaceuticals in wastewater. Among the parameters studied are: time of storage, temperature and pH. Over 60 analytes were targeted including stimulants, opioid and morphine derivatives, benzodiazepines, antidepressants, dissociative anaesthetics, drug precursors, human urine indicators and their metabolites. The lack of stability of analytes in raw wastewater was found to be significant for many compounds. For instance, 34% of compounds studied reported a stability change >15% after only 12 h in raw wastewater stored at 2 °C; a very important finding given that wastewater is typically collected with the use of 24 h composite samplers. The stability of these compounds is also critical given the recent development of so-called 'sewage forensics' or 'sewage epidemiology' in which concentrations of target drug residues in wastewater are used to back-calculate drug consumption. Without an understanding of stability, under (or over) reporting of consumption estimations may take place. PMID:21968350

  8. Identification of active ingredients in dietary supplements using non-destructive mass spectrometry and liquid chromatography-mass spectrometry.

    PubMed

    Saka, Kanju; Konuma, Kiyotaka; Asai, Shigehiro; Unuma, Kana; Nakajima, Makoto; Yoshida, Ken-ichi

    2009-10-30

    A mid-forties woman purchased seven different dietary supplements from Thailand on the internet and subsequently died after taking these supplements. Since there were no ingredient labels on the supplements, we identified the active ingredients using direct analysis in real time-mass spectrometry (DART-MS), direct exposure probe-MS (DEP-MS), and liquid chromatography-MS (LC-MS). DART-MS gives exact molecular weights and DEP-MS shows the fragmentation of a molecule by electron ionization. Analyses using these two instruments are rapid and do not require extraction of the sample. The compounds predicted by DART-MS and DEP-MS were confirmed by LC-MS and the active ingredients of the seven dietary supplements were identified. PMID:19656645

  9. [Study of phospholipid profile of ovarian tumor by high performance liquid chromatography-mass spectrometry].

    PubMed

    Zhao, Sumin; Wang, Yisheng; Dou, Abo; Chen, Jing; Lu, Xin; Cao, Rui; Xu, Congjian; Xu, Guowang

    2011-09-01

    Ovarian tumor has been paid more and more attention since its influence on women's health and life quality is increasing. Ovarian cancer is one of the three gynecologic cancers, and its mortality is the highest one of them. Phospholipid metabolic profiling method based on high performance liquid chromatography-electrospray mass spectrometry (HPLC/ESI-MS) has been applied in the study of ovarian tumors including benign (B) and malignant (M) ovarian tumors. The data of phospholipid profile collected by HPLC/ESI-MS were transformed and the peak list was obtained with the commercial software automatically. The total differences of phospholipids among M, B and normal (N) groups were found with the orthogonal signal correction and partial least-squares (OSC-PLS). Further, the differential phospholipids were selected according to the S-plot, the variable importance value (VIP > 1) and p (p < 0.05). These phospholipids were plasmalogen phospatidylethanol, phosphatidylcholine, plasmalogen phosphatidylcholine, sphingomyelin and lysophosphatidylcholine. This research provides some new and useful information of what has happened in phospholipids of the women with ovarian tumors. PMID:22233070

  10. Hydrocarbon phenotyping of algal species using pyrolysis-gas chromatography mass spectrometry

    PubMed Central

    2010-01-01

    Background Biofuels derived from algae biomass and algae lipids might reduce dependence on fossil fuels. Existing analytical techniques need to facilitate rapid characterization of algal species by phenotyping hydrocarbon-related constituents. Results In this study, we compared the hydrocarbon rich algae Botryococcus braunii against the photoautotrophic model algae Chlamydomonas reinhardtii using pyrolysis-gas chromatography quadrupole mass spectrometry (pyGC-MS). Sequences of up to 48 dried samples can be analyzed using pyGC-MS in an automated manner without any sample preparation. Chromatograms of 30-min run times are sufficient to profile pyrolysis products from C8 to C40 carbon chain length. The freely available software tools AMDIS and SpectConnect enables straightforward data processing. In Botryococcus samples, we identified fatty acids, vitamins, sterols and fatty acid esters and several long chain hydrocarbons. The algae species C. reinhardtii, B. braunii race A and B. braunii race B were readily discriminated using their hydrocarbon phenotypes. Substructure annotation and spectral clustering yielded network graphs of similar components for visual overviews of abundant and minor constituents. Conclusion Pyrolysis-GC-MS facilitates large scale screening of hydrocarbon phenotypes for comparisons of strain differences in algae or impact of altered growth and nutrient conditions. PMID:20492649

  11. Nature of unresolved complex mixture in size-distributed emissions from residential wood combustion as measured by thermal desorption-gas chromatography-mass spectrometry

    Microsoft Academic Search

    Michael D. Hays; N. Dean Smith; Yuanji Dong

    2004-01-01

    Unresolved complex mixture (UCM) is an analytical artifact of gas chromatographs of combustion source-related fine aerosol extracts. In this study the UCM is examined in size-resolved fine aerosol emissions from residential wood combustion. The aerosols are sorted by size in an electrical low-pressure impactor (ELPI) and subsequently analyzed by thermal desorption\\/gas chromatography\\/mass spectrometry (TD\\/GC\\/MS). A semiquantitative system for predicting the

  12. The characterization of eight maceral concentrates by means of Curie point pyrolysis-gas chromatography and Curie point pyrolysis-gas chromatography-mass spectrometry

    Microsoft Academic Search

    Margriet Nip; J. W. de Leeuw; P. A. Schenck

    1988-01-01

    In order to study the relationships between the chemical structures of coals, coal macerals and their precursors (plant tissues), eight coal macerals originating from the Yorkshire coal basin (U.K.) were studied by Curie point pyrolysis-gas chromatography and Curie point pyrolysis-gas chromatography-mass spectrometry. The samples were selected on the basis of a previous study of a large set of macerals. The

  13. Assessment of Antifungal Drug Therapy in Autism by Measurement of Suspected Microbial Metabolites in Urine with Gas Chromatography-Mass Spectrometry

    Microsoft Academic Search

    William Shaw; Ellen Kassen; Enrique Chaves

    Context-Certain compounds found by gas chromatography-mass spectrometry in urine samples of children with autism might be produced by yeast in the gastrointestinal tract. Therefore, treatment with antifungal drugs might reduce clinical symptoms of autism. Objective-To determine if symptoms of autism and chemical compounds in urine samples of children with autism decreased after antifungal treatment. Design-A number of urinary organic acids

  14. Development of a headspace solid-phase microextraction\\/gas chromatography–mass spectrometry method for determination of organophosphorus pesticide residues in cow milk

    Microsoft Academic Search

    Frederico de M. Rodrigues; Paulo R. R. Mesquita; Lidia S. de Oliveira; Fabio S. de Oliveira; Adalberto Menezes Filho; Pedro. A. de P. Pereira; Jailson B. de Andrade

    2011-01-01

    In the past few years, organophosphorus compounds become one of the most widely used classes of pesticides due to their acute toxicity against a wide variety of pests. In this work, a method based on solid-phase microextraction in mode headspace (HS-SPME) coupled to gas chromatography–mass spectrometry (GC–MS) was developed and optimized through multivariate factorial design to determine residues of organophosphorus

  15. Characterization of Rhus vernicifera and Rhus succedanea lacquer films and their pyrolysis mechanisms studied using two-stage pyrolysis-gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    Noriyasu Niimura; Tetsuo Miyakoshi; Jun Onodera; Tetsuo Higuchi

    1996-01-01

    Rhus vernicifera and Rhus succedanea lacquers, which are used as a surface coating for wood, porcelain and metalware in Japan, were investigated using two-stage pyrolysis gas chromatography\\/mass spectrometry (Py-GC\\/MS). Urushiol and laccol components were detected in each lacquer film by pyrolysis at 400 °C. These are the monomers, and are characteristic of Rhus vernicifera and Rhus succedanea lacquer films. In

  16. Simultaneous determination of lincomycin and spectinomycin residues in animal tissues by gas chromatography-nitrogen phosphorus detection and gas chromatography-mass spectrometry with accelerated solvent extraction

    Microsoft Academic Search

    Y. Tao; D. Chen; G. Yu; H. Yu; Y. Pan; Y. Wang; L. Huang; Z. Yuan

    2011-01-01

    A new multi-dimensional analytical method using gas chromatography-nitrogen phosphorus detection (GC-NPD) and gas chromatography-mass spectrometry (GC-MS) was developed for qualitative and quantitative measurement of lincomycin and spectinomycin residues in food animal tissues. This method is based on a new extraction procedure using accelerated solvent extraction (ASE). The analytes were extracted by phosphate buffer with trichloroacetic acid de-proteinisation and clean-up by

  17. Characterisation of lake-aquatic humic matter isolated with two different sorbing solid techniques: tetramethylammonium hydroxide treatment and pyrolysis-gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    Tero Lehtonen; Juhani Peuravuori; Kalevi Pihlaja

    2000-01-01

    Tetramethylammonium hydroxide (TMAH) treatment followed up with pyrolysis-gas chromatography\\/mass spectrometry (Py-GC\\/MS) was applied to characterise the structural composition of lake aquatic humic matter (HM). The HM samples were isolated with two different chromatographic methods: (1) non-ionic sorbing solid (standard XAD technique) with preacidification of a water sample to pH 2; and (2) weakly basic anion exchanger (DEAE, diethylaminoethyl cellulose) without

  18. Use of pyrolysis-gas chromatography\\/mass spectrometry to characterise binding media and protectives from a Coronelli’s terrestrial globe

    Microsoft Academic Search

    G. Chiavari; D. Fabbri; G. C. Galletti; S. Prati; N. Scianna

    2006-01-01

    During one of Coronelli's terrestrial globes restoration, belonging to the Bologna University, we found some substances considered not to be original. Their presence was both on the globe surface and under one of the gores. In order to characterise the organic material (original or added in restoring procedures) we employed pyrolysis-gas chromatography\\/mass spectrometry (Py-GC\\/MS). The analytical results reveal the presence

  19. Identification of natural dyes used in works of art by pyrolysis–gas chromatography\\/mass spectrometry combined with in situ trimethylsilylation

    Microsoft Academic Search

    María José Casas-Catalán; María Teresa Doménech-Carbó

    2005-01-01

    Samples of four natural dyes from different organic families—natural madder (anthraquinonoid), curcuma (curcuminoid), saffron (carotenoid) and indigo (indigotic)—were analysed using a new procedure based on pyrolysis–gas chromatography\\/mass spectrometry (Py–GC\\/MS), which includes the on-line derivatisation of the natural dyes using hexamethyldisilazane (HMDS). In addition, a previous procedure involving the addition of a 10% H2SO4 aqueous solution to the dye and further

  20. Application of solid-phase microextraction combined with gas chromatography–mass spectrometry to the determination of butylated hydroxytoluene in bottled drinking water

    Microsoft Academic Search

    Norma B Tombesi; Hugo Freije

    2002-01-01

    Butylated hydroxytoluene (BHT) is an antioxidant utilized as additive in foods and packaging plastic. Its presence in drinking water is possible if it is used as an antioxidant in the packaging plastic because it may migrate into the package’s contents. A method for the determination of BHT in water by means of solid-phase microextraction and gas chromatography–mass spectrometry has been

  1. Quantitative determination of some volatile suspected allergens in cosmetic creams spread on skin by direct contact sorptive tape extraction–gas chromatography–mass spectrometry

    Microsoft Academic Search

    B. Sgorbini; M. R. Ruosi; C. Cordero; E. Liberto; P. Rubiolo; C. Bicchi

    2010-01-01

    This study describes a method based on direct contact sorptive tape extraction followed by on-line thermal desorption gas chromatography–mass spectrometry (DC-STE–GC–MS) to detect and quantify a group of suspected volatile allergens on the European Union (E.U.) list and a related compound on the skin (the stratum corneum) of volunteers treated with a cream of known composition fortified with the reference

  2. Determination of anabolic steroids in human urine by automated in-tube solid-phase microextraction coupled with liquid chromatography–mass spectrometry

    Microsoft Academic Search

    Keita Saito; Katsuharu Yagi; Atsushi Ishizaki; Hiroyuki Kataoka

    2010-01-01

    A simple, rapid and sensitive method was developed for determining the presence of seven anabolic steroids (boldenone, nandrolone, testosterone, methyltestosterone, epiandrosterone, androsterone, and atnozolol) in human urine. Glucuronide-conjugates of these compounds were hydrolyzed with ?-glucuronidase. The anabolic steroids were analyzed by on-line in-tube solid-phase microextraction (SPME) coupled with liquid chromatography–mass spectrometry (LC–MS). The steroids were separated within 14min by high

  3. Determination of nicotine, cotinine, and related alkaloids in human urine and saliva by automated in-tube solid-phase microextraction coupled with liquid chromatography–mass spectrometry

    Microsoft Academic Search

    Hiroyuki Kataoka; Reiko Inoue; Katsuharu Yagi; Keita Saito

    2009-01-01

    A simple, rapid and sensitive method for the determination of nicotine, cotinine, nornicotine, anabasine, and anatabine in human urine and saliva was developed. These compounds were analyzed by on-line in-tube solid-phase microextraction (SPME) coupled with liquid chromatography–mass spectrometry (LC–MS). Nicotine, cotinine and related alkaloids were separated within 7min by high performance liquid chromatography (HPLC) using a Synergi 4u POLAR-RP 80A

  4. Contribution of oxidized tallow to aroma characteristics of beeflike process flavour assessed by gas chromatography-mass spectrometry and partial least squares regression.

    PubMed

    Song, Shiqing; Zhang, Xiaoming; Xiao, Zuobing; Niu, Yunwei; Hayat, Khizar; Eric, Karangwa

    2012-09-01

    Flavour profiles of seven beeflike process flavours (BFs) including non-oxidized or oxidized tallow were comparatively analysed by electronic nose, gas chromatography-mass spectrometry (GC-MS) and descriptive sensory analysis to characterize the headspace of BFs. Analysis of volatiles by GC-MS indicated that the effect of oxidized tallow with moderate oxidization level on Maillard reaction was more prominent than that of others, which potentially could result in an optimal meat flavour with strong, harmony and species-specific characteristics detected by sensory analysis. In addition, electronic nose data confirmed the accuracy of the GC-MS and sensory analysis results. Correlation analysis of the electronic nose measurements, sensory evaluation and characteristic compounds through Partial Least Squares Regression (PLSR) further explained that moderate oxidized tallow with peroxide value (PV) of 87.67-160 mequiv./kg, the p-anisidine value (p-AV) of 30.57-50, and the acid value (AV) of 1.8-2.2 mg KOH/g tallow was a desirable precursor for imparting aroma characteristics of beef flavour. PMID:22858364

  5. Automated label-free quantification of metabolites from liquid chromatography-mass spectrometry data.

    PubMed

    Kenar, Erhan; Franken, Holger; Forcisi, Sara; Wörmann, Kilian; Häring, Hans-Ulrich; Lehmann, Rainer; Schmitt-Kopplin, Philippe; Zell, Andreas; Kohlbacher, Oliver

    2014-01-01

    Liquid chromatography coupled to mass spectrometry (LC-MS) has become a standard technology in metabolomics. In particular, label-free quantification based on LC-MS is easily amenable to large-scale studies and thus well suited to clinical metabolomics. Large-scale studies, however, require automated processing of the large and complex LC-MS datasets. We present a novel algorithm for the detection of mass traces and their aggregation into features (i.e. all signals caused by the same analyte species) that is computationally efficient and sensitive and that leads to reproducible quantification results. The algorithm is based on a sensitive detection of mass traces, which are then assembled into features based on mass-to-charge spacing, co-elution information, and a support vector machine-based classifier able to identify potential metabolite isotope patterns. The algorithm is not limited to metabolites but is applicable to a wide range of small molecules (e.g. lipidomics, peptidomics), as well as to other separation technologies. We assessed the algorithm's robustness with regard to varying noise levels on synthetic data and then validated the approach on experimental data investigating human plasma samples. We obtained excellent results in a fully automated data-processing pipeline with respect to both accuracy and reproducibility. Relative to state-of-the art algorithms, ours demonstrated increased precision and recall of the method. The algorithm is available as part of the open-source software package OpenMS and runs on all major operating systems. PMID:24176773

  6. Quantitation of ethyl glucuronide in serum & urine by gas chromatography - mass spectrometry

    PubMed Central

    Sharma, Priyamvada; Bharat, Venkatesh; Murthy, Pratima

    2015-01-01

    Background & objectives: Alcohol misuse has now become a serious public health problem and early intervention is important in minimizing the harm. Biochemical markers of recent and high levels of alcohol consumption can play an important role in providing feedback regarding the health consequences of alcohol misuse. Existing markers are not sensitive to recent consumption and in detecting early relapse. Ethyl glucuronide (EtG), a phase-II metabolite of ethanol is a promising marker of recent alcohol use and can be detected in body fluids. In this study an analytical technique for quantitation of EtG in body fluids using solid-phase extraction (SPE) and gas chromatography (GC) with mass spectrometric detection (MS) was developed and validated. Methods: De-proteinization of serum and urine samples was done with perchloric acid and hydrochloric acid, respectively. Serum samples were passed through phospholipids removal cartridges for further clean up. EtG was isolated using amino propyl solid phase extraction columns. Chromatographic separation was achieved by gas chromatography with mass spectrometry. Results: Limit of detection and limit of quantitation were 50 and 150 ng/ml for urine and 80 and 210 ng/ml for serum, respectively. Signal to noise ratio was 3:1, mean absolute recovery was 80-85 per cent. Significant correlation was obtained between breath alcohol and serum EtG levels (r=0.853) and urine EtG and time since last abuse (r = -0.903) in clinical samples. Interpretation & conclusions: In the absence of other standardized techniques to quantitate EtG in biological samples, this GC-MS method was found to have high throughput and was sensitive and specific. PMID:25857498

  7. Identification and confirmation of chemical residues by chromatography-mass spectrometry and other techniques

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A quantitative answer cannot exist in an analysis without a qualitative component to give enough confidence that the result meets the analytical needs for the analysis (i.e. the result relates to the analyte and not something else). Just as a quantitative method must typically undergo an empirical ...

  8. DETERMINATION OF ALDICARB RESIDUES IN WATER BY COMBINED HIGH PERFORMANCE LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY

    EPA Science Inventory

    Current gas chromtographic methods for the analysis of aldicarb (Temik) residues involve a number of time consuming steps including a liquid chromatographic separation of the residues, conversions to derivatives or common intermediates, and separate analyses of the intermediates....

  9. Liquid chromatography-mass spectrometry based serum peptidomic approach for renal clear cell carcinoma diagnosis.

    PubMed

    Huang, Zhenzhen; Zhang, Shudi; Hang, Wei; Chen, Yuedong; Zheng, Jiaxin; Li, Wei; Xing, Jinchun; Zhang, Jie; Zhu, Eryi; Yan, Xiaomei

    2014-11-01

    Serum peptidomic approach was applied to investigate the peptidomic signature and discover the clinical biomarkers and biomarker patterns for RCC patients. The holistic orthogonal partial least-squares-discriminant analysis (OPLS-DA) based on qualified profile data successfully classified RCC patients from healthy controls, showing 100% sensitivity and specificity. Following critical criteria, several peptides presenting significant differences in serum level were picked out. The unsupervised hierarchical cluster analysis on those peptides was performed, showing 100% sensitivity and 93.3% specificity for RCC diagnosis regarding the present samples. Besides, receiver-operating characteristic (ROC) analysis was applied on single peptide biomarkers, with four peptides showing excellent predictive power. Among them, IYQLNSKLV and AGISMRSGDSPQD are reported for the first time for cancer detection. PMID:25168216

  10. Magnetic solid phase extraction and gas chromatography-mass spectrometrical analysis of sixteen polycyclic aromatic hydrocarbons.

    PubMed

    Cai, Ying; Yan, Zhihong; NguyenVan, Manh; Wang, Lijia; Cai, Qingyun

    2015-08-01

    Fluorenyl functionalized superparamagnetic core/shell magnetic nanoparticles (MNPs, Fe3O4@SiO2@Flu) were prepared and characterized by transmission electron microscope, X-ray diffraction and infrared spectroscopy. The MNPs having an average diameter of 200nm were then used as solid-phase extraction sorbent for the determination of 16 priority pollutants polycyclic aromatic hydrocarbons (PAHs) in water samples designated by United States Environmental Protection Agency (U.S. EPA). The main influencing parameters, including sorbent amount, desorption solvent, sample volume and extraction time were optimized. Analyses were performed on gas chromatography-mass spectrometry (GC-MS) using selected ion monitoring (SIM) mode. Method validation proved the feasibility of the developed sorbents for the quantitation of the investigated analytes at trace levels. Limit of detection ranging from 0.5 to 4.0ng/L were obtained. The repeatability was investigated by evaluating the intra- and inter-day precisions with relative standard deviations (RSDs) lower than 13.1%. Finally, the proposed method was successfully applied for the determination of PAHs in water samples with the recoveries in the range of 96.0-106.7%. PMID:26122856

  11. Method Development for the Determination of Fluorotelomer Alcohols in Soils by Gas Chromatography Mass Spectrometry

    EPA Science Inventory

    Fluorotelomer alcohols (FTOHs) have been widely studied as precursors to perfluorocarboxylates, e.g. 8:2 FTOH degrades to perfluorooctanoic acid (PFOA). This presentation describes an analytical method for the extraction and analysis of 6:2, 8:2, and 10:2 FTOHs. Gas chromatograph...

  12. Measurement of ethyl glucuronide in vitreous humor with liquid chromatography–mass spectrometry

    Microsoft Academic Search

    Alper Keten; Ali Riza Tumer; Aysun Balseven-Odabasi

    2009-01-01

    BackgroundIt is important to detect alcohol intake in postmortem investigations. However it can be difficult to interpret the results of alcohol analysis in putrefied corpses. To avoid this difficulty, there have been studies on detection of ethyl glucuronide (EtG), a non-oxidative metabolite of ethyl alcohol. The aim of this study was investigate EtG levels in vitreous humor (VH), a valuable

  13. An untargeted gas chromatography mass spectrometry metabolomics platform for marine polychaetes.

    PubMed

    Fernández-Varela, R; Tomasi, G; Christensen, J H

    2015-03-01

    The development of an appropriate extraction method for untargeted environmental metabolomic analysis of marine polychaetes could promote their use for environmental monitoring purposes. To this end, we compared four extraction methods on the marine polychaete Nereis virens both exposed to crude oil and non-exposed. XCMS was used for feature detection and preprocessing; different normalization and scaling approaches were tested; and principal component analysis (PCA) was used together with basic statistical tests to ascertain common metabolic patterns and determine the most suitable extraction method. We conclude that a two-step extraction procedure with 80:20 (v/v) methanol:water on freeze dried polychaete tissue provides the best trade-off between analysis time, and extraction efficiency and intermediate reproducibility. No definitive conclusions could be drawn about the ability of the method to discriminate controls and crude oils in actual biological replicates because the experiment was carried out by design on analytical replicates only. We show that the normalization to the sum of all the common features, and the use of a weighted least squares criterion to fit the PCA by means of scaling to the median absolute deviation (MAD) of the pooled quality control samples significantly improved the clustering of controls and crude oil exposed samples. The scaling alone led to an increase of 19% in explained variance compared to ordinary PCA. PMID:25660527

  14. Rapid determination of spore chemistry using thermochemolysis gas chromatography-mass spectrometry and micro-Fourier transform infrared spectroscopy.

    PubMed

    Watson, Jonathan S; Sephton, Mark A; Sephton, Sarah V; Self, Stephen; Fraser, Wesley T; Lomax, Barry H; Gilmour, Iain; Wellman, Charles H; Beerling, David J

    2007-06-01

    Spore chemistry is at the centre of investigations aimed at producing a proxy record of harmful ultraviolet radiation (UV-B) through time. A biochemical proxy is essential owing to an absence of long-term (century or more) instrumental records. Spore cell material contains UV-B absorbing compounds that appear to be synthesised in variable amounts dependent on the ambient UV-B flux. To facilitate these investigations we have developed a rapid method for detecting variations in spore chemistry using combined thermochemolysis gas chromatography-mass spectrometry and micro-Fourier transform infrared spectroscopy. Our method was tested using spores obtained from five populations of the tropical lycopsid Lycopodium cernuum growing across an altitudinal gradient (650-1981 m a.s.l.) in S.E. Asia with the assumption that they experienced a range of UV-B radiation doses. Thermochemolysis and subsequent pyrolysis liberated UV-B pigments (ferulic and para-coumaric acid) from the spores. All of the aromatic compounds liberated from spores by thermochemolysis and pyrolysis were active in UV-B protection. The various functional groups associated with UV-B protecting pigments were rapidly detected by micro-FTIR and included the aromatic C[double bond, length as m-dash]C absorption band which was exclusive to the pigments. We show increases in micro-FTIR aromatic absorption (1510 cm(-1)) with altitude that may reflect a chemical response to higher UV-B flux. Our results indicate that rapid chemical analyses of historical spore samples could provide a record ideally suited to investigations of a proxy for stratospheric O3 layer variability and UV-B flux over historical (century to millennia) timescales. PMID:17549272

  15. Determination of ricin by nano liquid chromatography/mass spectrometry after extraction using lactose-immobilized monolithic silica spin column.

    PubMed

    Kanamori-Kataoka, Mieko; Kato, Haruhito; Uzawa, Hirotaka; Ohta, Shigenori; Takei, Yoshiyuki; Furuno, Masahiro; Seto, Yasuo

    2011-08-01

    Ricin is a glycosylated proteinous toxin that is registered as toxic substance by Chemical Weapons convention. Current detection methods can result in false negatives and/or positives, and their criteria are not based on the identification of the protein amino acid sequences. In this study, lactose-immobilized monolithic silica extraction followed by tryptic digestion and liquid chromatography/mass spectrometry (LC/MS) was developed as a method for rapid and accurate determination of ricin. Lactose, which was immobilized on monolithic silica, was used as a capture ligand for ricin extraction from the sample solution, and the silica was supported in a disk-packed spin column. Recovery of ricin was more than 40%. After extraction, the extract was digested with trypsin and analyzed by LC/MS. The accurate masses of molecular ions and MS/MS spectra of the separated peptide peaks were measured by Fourier transform-MS and linear iontrap-MS, respectively. Six peptides, which were derived from the ricin A-(m/z 537.8, 448.8 and 586.8) and B-chains (m/z 701.3, 647.8 and 616.8), were chosen as marker peptides for the identification of ricin. Among these marker peptides, two peptides were ricin-specific. This method was applied to the determination of ricin from crude samples. The monolithic silica extraction removed most contaminant peaks from the total ion chromatogram of the sample, and the six marker peptides were clearly detected by LC/MS. It takes about 5 h for detection and identification of more than 8 ng/ml of ricin through the whole handling, and this procedure will be able to deal with the terrorism using chemical weapon. PMID:21834021

  16. Efficient separations of intact proteins using slip-flow with nano-liquid chromatography-mass spectrometry.

    PubMed

    Wu, Zhen; Wei, Bingchuan; Zhang, Ximo; Wirth, Mary J

    2014-02-01

    A capillary with a pulled tip, densely packed with silica particles of 0.47 ?m in diameter, is shown to provide higher peak capacity and sensitivity in the separation of intact proteins by reversed-phase liquid chromatography-mass spectrometry (LC-MS). For a C18 bonded phase, slip flow gave a 10-fold flow enhancement to allow for stable nanospray with a 4-cm column length. Model proteins were studied: ribonuclease A, trypsin inhibitor, and carbonic anhydrase, where the latter had impurities of superoxide dismutase and ubiquitin. The proteins were well separated at room temperature with negligible peak tailing. The peak capacity for ubiquitin was 195 for a 10-min gradient and 315 for a 40-min gradient based on Gaussian fitting of the entire peak, rather than extrapolating the full-width at half-maximum. Separation of a cell lysate with a 60 min gradient showed extremely high peak capacities of 750 and above for a peptide and relatively homogeneous proteins. Clean, low noise mass spectra for each model protein were obtained. The physical widths of the peaks were an order of magnitude narrower than those of conventional columns, giving increased sensitivity. All proteins except ubiquitin exhibited significant heterogeneity apparently due to multiple proteoforms, as indicated by both peak shapes and mass spectra. The chromatograms exhibited excellent reproducibility in retention time, with relative standard deviations of 0.09 to 0.34%. The results indicate that submicrometer particles are promising for improving the separation dimension of LC in top-down proteomics. PMID:24383398

  17. [Determination of 10 sedative-hypnotics in human plasma using pulse splitless injection technique and gas chromatography-mass spectrometry].

    PubMed

    Chang, Qing; Ma, Hongying; Wang, Fangjie; Ou, Honglian; Zou, Ming

    2011-11-01

    A simple, precise and sensitive gas chromatography-mass spectrometry (GC-MS) method coupled with pulse splitless injection technique was developed for the determination of 10 sedative-hypnotics (barbital, amobarbital, phenobarbital, oxazepam, diazepam, nitrazepam, clonazepam, estazolam, alprazolam, triazolam) in human plasma. The drugs spiked in plasma were extracted with ethyl acetate after alkalization with 0.1 mol/L NaOH solution. The organic solvent was evaporated under nitrogen stream, and the residues were redissolved by ethyl acetate. The separation was performed on an HP-5MS column (30 m x 250 microm x 0.25 microm). The analytes were determined and identified using selected ion monitoring (SIM) mode and scan mode, respectively. The internal standard method was used for the determination. The target analytes were well separated from each other on their SIM chromatograms and also on the total ion current (TIC) chromatograms. The blank extract from human plasma gave no peaks that interfered with all the analytes on the chromatogram. The calibration curves for 10 sedative-hypnotics showed excellent linearity. The correlation coefficients of all the drugs were higher than 0.9954. The recoveries of the drugs spiked in human plasma ranged from 92.28% to 111.7%, and the relative standard deviations (RSDs) of intra-day and inter-day determinations were from 4.09% to 14.26%. The detection limits ranged from 2 to 20 microg/L. The method is simple, reliable, rapid and sensitive for the determination and the quantification of 10 sedative-hypnotics in human plasma and seems to be useful in the practice of clinical toxicological cases. PMID:22393695

  18. Serum level of 19-hydroxyandrostenedione during pregnancy and at delivery determined by gas chromatography/mass spectrometry

    SciTech Connect

    Osawa, Y.; Ohnishi, S.; Yarborough, C.; Ohigashi, S.; Kosaki, T.; Hashino, M.; Yanaihara, T.; Nakayama, T. (Medical Foundation of Buffalo Research Institute, NY (USA))

    1990-04-01

    19-Hydroxyandrostenedione (19-OHA) is secreted from the adrenal glands in men and women and also from the placenta during pregnancy. It has been found to cause hypertension in animal models. We have synthesized (7,7-2H2)-19-OHA with high deuterium content and, together with (7,7-2H2)A and (9,11-2H2)estrone (E1), have developed a quantitative assay of serum level 19-OHA, A, and E1 using the gas chromatography/mass spectrometry-mass fragmentography method to monitor individual subjects throughout pregnancy. The labeled 19-OHA, used as internal standard, showed only 6.73% of unlabeled compound. Recovery of standard 19-OHA, A, and E1 (5,000 pg each) added to male plasma was 97.4 +/- 2.3%, 96.3 +/- 2.1%, and 100.1 +/- 4.1% (mean +/- SD), respectively; the intraassay coefficient of variation was 2.1%, 3.5%, and 3.8%, respectively. Ten pregnant subjects without complications and 10 pregnant subjects near term with hypertension were selected (with informed consent). The 19-OHA and E1 serum concentrations of maternal venous blood from uncomplicated pregnancies increased significantly as gestation progressed (19-OHA: first trimester, 225 +/- 72; second trimester, 656 +/- 325; third trimester, 1,518 +/- 544 pg/ml), reaching the highest level at delivery (19-OHA: 1,735 +/- 684 pg/ml). Whereas a positive correlation was found between the level of 19-OHA and E1, no apparent change of the A level was observed during pregnancy. Levels of the three steroid hormones in pregnancy complicated by hypertension in the second and third trimester were not found to be significantly different from those of normal pregnancy (19-OHA of hypertensive subjects: second trimester, 762 +/- 349; third trimester, 1,473 +/- 491 pg/ml).

  19. Assessing Gibberellins Oxidase Activity by Anion Exchange/Hydrophobic Polymer Monolithic Capillary Liquid Chromatography-Mass Spectrometry

    PubMed Central

    Liu, Jiu-Feng; Wu, Yan; Feng, Yu-Qi; Yuan, Bi-Feng

    2013-01-01

    Bioactive gibberellins (GAs) play a key regulatory role in plant growth and development. In the biosynthesis of GAs, GA3-oxidase catalyzes the final step to produce bioactive GAs. Thus, the evaluation of GA3-oxidase activity is critical for elucidating the regulation mechanism of plant growth controlled by GAs. However, assessing catalytic activity of endogenous GA3-oxidase remains challenging. In the current study, we developed a capillary liquid chromatographymass spectrometry (cLC-MS) method for the sensitive assay of in-vitro recombinant or endogenous GA3-oxidase by analyzing the catalytic substrates and products of GA3-oxidase (GA1, GA4, GA9, GA20). An anion exchange/hydrophobic poly([2-(methacryloyloxy)ethyl]trimethylammonium-co-divinylbenzene-co-ethylene glycol dimethacrylate)(META-co-DVB-co-EDMA) monolithic column was successfully prepared for the separation of all target GAs. The limits of detection (LODs, Signal/Noise?=?3) of GAs were in the range of 0.62–0.90 fmol. We determined the kinetic parameters (Km) of recombinant GA3-oxidase in Escherichia coli (E. coli) cell lysates, which is consistent with previous reports. Furthermore, by using isotope labeled substrates, we successfully evaluated the activity of endogenous GA3-oxidase that converts GA9 to GA4 in four types of plant samples, which is, to the best of our knowledge, the first report for the quantification of the activity of endogenous GA3-oxidase in plant. Taken together, the method developed here provides a good solution for the evaluation of endogenous GA3-oxidase activity in plant, which may promote the in-depth study of the growth regulation mechanism governed by GAs in plant physiology. PMID:23922762

  20. A search for amino acids and nucleobases in the Martian meteorite Roberts Massif 04262 using liquid chromatography-mass spectrometry

    NASA Astrophysics Data System (ADS)

    Callahan, Michael P.; Burton, Aaron S.; Elsila, Jamie E.; Baker, Eleni M.; Smith, Karen E.; Glavin, Daniel P.; Dworkin, Jason P.

    2013-05-01

    The investigation into whether Mars contains signatures of past or present life is of great interest to science and society. Amino acids and nucleobases are compounds that are essential for all known life on Earth and are excellent target molecules in the search for potential Martian biomarkers or prebiotic chemistry. Martian meteorites represent the only samples from Mars that can be studied directly in the laboratory on Earth. Here, we analyzed the amino acid and nucleobase content of the shergottite Roberts Massif (RBT) 04262 using liquid chromatography-mass spectrometry. We did not detect any nucleobases above our detection limit in formic acid extracts; however, we did measure a suite of protein and nonprotein amino acids in hot-water extracts with high relative abundances of ?-alanine and ?-amino-n-butyric acid. The presence of only low (to absent) levels of several proteinogenic amino acids and a lack of nucleobases suggest that this meteorite fragment is fairly uncontaminated with respect to these common biological compounds. The distribution of straight-chained amine-terminal n-?-amino acids in RBT 04262 resembled those previously measured in thermally altered carbonaceous meteorites (Burton et al. 2012; Chan et al. 2012). A carbon isotope ratio of -24‰ ± 6‰ for ?-alanine in RBT 04262 is in the range of reduced organic carbon previously measured in Martian meteorites (Steele et al. 2012). The presence of n-?-amino acids may be due to a high temperature Fischer-Tropsch-type synthesis during igneous processing on Mars or impact ejection of the meteorites from Mars, but more experimental data are needed to support these hypotheses.

  1. Development of versatile isotopic labeling reagents for profiling the amine submetabolome by liquid chromatography-mass spectrometry.

    PubMed

    Zhou, Ruokun; Huan, Tao; Li, Liang

    2015-06-30

    Metabolomic profiling involves relative quantification of metabolites in comparative samples and identification of the significant metabolites that differentiate different groups (e.g., diseased vs. controls). Chemical isotope labeling (CIL) liquid chromatography-mass spectrometry (LC-MS) is an enabling technique that can provide improved metabolome coverage and metabolite quantification. However, chemical identification of labeled metabolites can still be a challenge. In this work, a new set of isotopic labeling reagents offering versatile properties to enhance both detection and identification are described. They were prepared by a glycine molecule (or its isotopic counterpart) and an aromatic acid with varying structures through a simple three-step synthesis route. In addition to relatively low costs of synthesizing the reagents, this reaction route allows adjusting reagent property in accordance with the desired application objective. To date, two isotopic reagents, 4-dimethylaminobenzoylamido acetic acid N-hydroxylsuccinimide ester (DBAA-NHS) and 4-methoxybenzoylamido acetic acid N-hydroxylsuccinimide ester (MBAA-NHS), for labeling the amine-containing metabolites (i.e., amine submetabolome) have been synthesized. The labeling conditions and the related LC-MS method have been optimized. We demonstrate that DBAA labeling can increase the metabolite detectability because of the presence of an electrospray ionization (ESI)-active dimethylaminobenzoyl group. On the other hand, MBAA labeled metabolites can be fragmented in MS/MS and pseudo MS(3) experiments to provide structural information on metabolites of interest. Thus, these reagents can be tailored to quantitative profiling of the amine submetabolome as well as metabolite identification in metabolomics applications. PMID:26041526

  2. A Search for Amino Acids and Nucleobases in the Martian Meteorite Roberts Massif 04262 Using Liquid Chromatography-Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Callahan, Michael P.; Burton, Aaron S.; Elsila, Jamie E.; Baker, Eleni M.; Smith, Karen E.; Glavin, Daniel P.; Dworkin, Jason P.

    2013-01-01

    The investigation into whether Mars contains signatures of past or present life is of great interest to science and society. Amino acids and nucleobases are compounds that are essential for all known life on Earth and are excellent target molecules in the search for potential Martian biomarkers or prebiotic chemistry. Martian meteorites represent the only samples from Mars that can be studied directly in the laboratory on Earth. Here, we analyzed the amino acid and nucleobase content of the shergottite Roberts Massif (RBT) 04262 using liquid chromatography-mass spectrometry. We did not detect any nucleobases above our detection limit in formic acid extracts; however, we did measure a suite of protein and nonprotein amino acids in hot-water extracts with high relative abundances of beta-alanine and gamma-amino-eta-butyric acid. The presence of only low (to absent) levels of several proteinogenic amino acids and a lack of nucleobases suggest that this meteorite fragment is fairly uncontaminated with respect to these common biological compounds. The distribution of straight-chained amine-terminal eta-omega-amino acids in RBT 04262 resembled those previously measured in thermally altered carbonaceous meteorites. A carbon isotope ratio of -24(0/00) +/- 6(0/00) for beta-alanine in RBT 04262 is in the range of reduced organic carbon previously measured in Martian meteorites (Steele et al. 2012). The presence of eta-omega-amino acids may be due to a high temperature Fischer-Tropschtype synthesis during igneous processing on Mars or impact ejection of the meteorites from Mars, but more experimental data are needed to support these hypotheses.

  3. Cerumen of Australian stingless bees ( Tetragonula carbonaria): gas chromatography-mass spectrometry fingerprints and potential anti-inflammatory properties

    NASA Astrophysics Data System (ADS)

    Massaro, Flavia Carmelina; Brooks, Peter Richard; Wallace, Helen Margaret; Russell, Fraser Donald

    2011-04-01

    Cerumen, or propolis, is a mixture of plant resins enriched with bee secretions. In Australia, stingless bees are important pollinators that use cerumen for nest construction and possibly for colony's health. While extensive research attests to the therapeutic properties of honeybee ( Apis mellifera) propolis, the biological and medicinal properties of Australian stingless bee cerumen are largely unknown. In this study, the chemical and biological properties of polar extracts of cerumen from Tetragonula carbonaria in South East Queensland, Australia were investigated using gas chromatography-mass spectrometry (GC-MS) analyses and in vitro 5-lipoxygenase (5-LOX) cell-free assays. Extracts were tested against comparative (commercial tincture of A. mellifera propolis) and positive controls (Trolox and gallic acid). Distinct GC-MS fingerprints of a mixed diterpenic profile typical of native bee cerumen were obtained with pimaric acid (6.31 ± 0.97%, w/w), isopimaric acid (12.23 ± 3.03%, w/w), and gallic acid (5.79 ± 0.81%, w/w) tentatively identified as useful chemical markers. Characteristic flavonoids and prenylated phenolics found in honeybee propolis were absent. Cerumen extracts from T. carbonaria inhibited activity of 5-LOX, an enzyme known to catalyse production of proinflammatory mediators (IC50 19.97 ± 2.67 ?g/ml, mean ± SEM, n = 4). Extracts had similar potency to Trolox (IC50 12.78 ± 1.82 ?g/ml), but were less potent than honeybee propolis (IC50 5.90 ± 0.62 ?g/ml) or gallic acid (IC50 5.62 ± 0.35 ?g/ml, P < 0.001). These findings warrant further investigation of the ecological and medicinal properties of this stingless bee cerumen, which may herald a commercial potential for the Australian beekeeping industry.

  4. Assessing gibberellins oxidase activity by anion exchange/hydrophobic polymer monolithic capillary liquid chromatography-mass spectrometry.

    PubMed

    Chen, Ming-Luan; Su, Xin; Xiong, Wei; Liu, Jiu-Feng; Wu, Yan; Feng, Yu-Qi; Yuan, Bi-Feng

    2013-01-01

    Bioactive gibberellins (GAs) play a key regulatory role in plant growth and development. In the biosynthesis of GAs, GA3-oxidase catalyzes the final step to produce bioactive GAs. Thus, the evaluation of GA3-oxidase activity is critical for elucidating the regulation mechanism of plant growth controlled by GAs. However, assessing catalytic activity of endogenous GA3-oxidase remains challenging. In the current study, we developed a capillary liquid chromatography--mass spectrometry (cLC-MS) method for the sensitive assay of in-vitro recombinant or endogenous GA3-oxidase by analyzing the catalytic substrates and products of GA3-oxidase (GA1, GA4, GA9, GA20). An anion exchange/hydrophobic poly([2-(methacryloyloxy)ethyl]trimethylammonium-co-divinylbenzene-co-ethylene glycol dimethacrylate)(META-co-DVB-co-EDMA) monolithic column was successfully prepared for the separation of all target GAs. The limits of detection (LODs, Signal/Noise = 3) of GAs were in the range of 0.62-0.90 fmol. We determined the kinetic parameters (K m) of recombinant GA3-oxidase in Escherichia coli (E. coli) cell lysates, which is consistent with previous reports. Furthermore, by using isotope labeled substrates, we successfully evaluated the activity of endogenous GA3-oxidase that converts GA9 to GA4 in four types of plant samples, which is, to the best of our knowledge, the first report for the quantification of the activity of endogenous GA3-oxidase in plant. Taken together, the method developed here provides a good solution for the evaluation of endogenous GA3-oxidase activity in plant, which may promote the in-depth study of the growth regulation mechanism governed by GAs in plant physiology. PMID:23922762

  5. Electrospray Ionization Mass Spectrometry of Tetrodotoxin and Its Analogs: Liquid Chromatography\\/Mass Spectrometry, Tandem Mass Spectrometry, and Liquid Chromatography\\/Tandem Mass Spectrometry

    Microsoft Academic Search

    Yuki Shoji; Mari Yotsu-Yamashita; Teruo Miyazawa; Takeshi Yasumoto

    2001-01-01

    Tetrodotoxin (TTX), a powerful sodium channel blocker, usually exists as a mixture of its analogs (TTXs) in natural sources. Due to the structural variation, some analogs are difficult to detect using the postcolumn liquid chromatography-fluorescent detection (LC-FLD) system. Liquid chromatography\\/electrospray ionization mass spectrometry (LC\\/ESI-MS) analysis of TTXs can be achieved by a combination of chromatography on a reversed-phase column with

  6. Metabolomics of developing zebrafish embryos using gas chromatography- and liquid chromatography-mass spectrometry.

    PubMed

    Huang, Shao-Min; Xu, Fengguo; Lam, Siew Hong; Gong, Zhiyuan; Ong, Choon Nam

    2013-06-01

    Zebrafish embryogenesis is a rapid process driven by a myriad of gene products and small molecules. As previous studies have detailed the relevant transcriptional and proteomics changes, here we assess the metabolomic changes that occur at different stages of embryogenesis (4, 8, 12, 24 and 48 hours post fertilization). Metabolite levels were detected using GC-MS and LC-MS, following which multivariate analysis (OPLS-DA) was applied to identify metabolites that were differentially regulated throughout embryogenesis. From the two robust OPLS-DA models that were generated (Q(2)(cum) = 0.940 and Q(2)(cum) = 0.894), a total of 60 detected metabolites (20 from GC-MS, 40 from LC-MS) were identified and found to be important in discriminating between developmental stages. Hierarchical clustering analysis was applied to the dataset and metabolite classes such as amino acids and lipids were shown to be differentially regulated. Biologically relevant transcriptomic and proteomic data were associated with metabolites to provide a more holistic systems perspective of embryogenesis. In summary, the metabolic profiles of different developmental stages highlight the dynamic changes occurring during embryogenesis. These data could serve as a basis for future toxicological or developmental studies. PMID:23475132

  7. Comparative evaluation of preprocessing freeware on chromatography/mass spectrometry data for signature discovery.

    PubMed

    Coble, Jamie B; Fraga, Carlos G

    2014-09-01

    Preprocessing software, which converts large instrumental data sets into a manageable format for data analysis, is crucial for the discovery of chemical signatures in metabolomics, chemical forensics, and other signature-focused disciplines. Here, four freely available and published preprocessing tools known as MetAlign, MZmine, SpectConnect, and XCMS were evaluated for impurity profiling using nominal mass GC/MS data and accurate mass LC/MS data. Both data sets were previously collected from the analysis of replicate samples from multiple stocks of a nerve-agent precursor and method blanks. Parameters were optimized for each of the four tools for the untargeted detection, matching, and cataloging of chromatographic peaks from impurities present in the stock samples. The peak table generated by each preprocessing tool was analyzed to determine the number of impurity components detected in all replicate samples per stock and absent in the method blanks. A cumulative set of impurity components was then generated using all available peak tables and used as a reference to calculate the percent of component detections for each tool, in which 100% indicated the detection of every known component present in a stock. For the nominal mass GC/MS data, MetAlign had the most component detections followed by MZmine, SpectConnect, and XCMS with detection percentages of 83, 60, 47, and 41%, respectively. For the accurate mass LC/MS data, the order was MetAlign, XCMS, and MZmine with detection percentages of 80, 45, and 35%, respectively. SpectConnect did not function for the accurate mass LC/MS data. Larger detection percentages were obtained by combining the top performer with at least one of the other tools such as 96% by combining MetAlign with MZmine for the GC/MS data and 93% by combining MetAlign with XCMS for the LC/MS data. In terms of quantitative performance, the reported peak intensities from each tool had averaged absolute biases (relative to peak intensities obtained using instrument software) of 41, 4.4, 1.3 and 1.3% for SpectConnect, MetAlign, XCMS, and MZmine, respectively, for the GC/MS data. For the LC/MS data, the averaged absolute biases were 22, 4.5, and 3.1% for MetAlign, MZmine, and XCMS, respectively. In summary, MetAlign performed the best in terms of the number of component detections; however, more than one preprocessing tool should be considered to avoid missing impurities or other trace components as potential chemical signatures. PMID:25063004

  8. A lectin chromatography/mass spectrometry discovery workflow identifies putative biomarkers of aggressive breast cancers

    PubMed Central

    Drake, Penelope M.; Schilling, Birgit; Niles, Richard K.; Prakobphol, Akraporn; Li, Bensheng; Jung, Kwanyoung; Cho, Wonryeon; Braten, Miles; Inerowicz, Halina D.; Williams, Katherine; Albertolle, Matthew; Held, Jason M.; Iacovides, Demetris; Sorensen, Dylan J.; Griffith, Obi L.; Johansen, Eric; Zawadzka, Anna M.; Cusack, Michael P.; Allen, Simon; Gormley, Matthew; Hall, Steven C.; Witkowska, H. Ewa; Gray, Joe W.; Regnier, Fred; Gibson, Bradford W.; Fisher, Susan J.

    2012-01-01

    We used a lectin chromatography/MS-based approach to screen conditioned medium from a panel of luminal (less aggressive) and triple negative (more aggressive) breast cancer cell lines (n = 5/subtype). The samples were fractionated using the lectins Aleuria aurantia (AAL) and Sambucus nigra agglutinin (SNA), which recognize fucose and sialic acid, respectively. The bound fractions were enzymatically N-deglycosylated and analyzed by LC-MS/MS. In total, we identified 533 glycoproteins, ~90% of which were components of the cell surface or extracellular matrix. We observed 1011 glycosites, 100 of which were solely detected in ?3 triple negative lines. Statistical analyses suggested that a number of these glycosites were triple negative-specific and thus potential biomarkers for this tumor subtype. An analysis of RNAseq data revealed that approximately half of the mRNAs encoding the protein scaffolds that carried potential biomarker glycosites were upregulated in triple negative vs. luminal cell lines, and that a number of genes encoding fucosyl- or sialyltransferases were differentially expressed between the two subtypes, suggesting that alterations in glycosylation may also drive candidate identification. Notably, the glycoproteins from which these putative biomarker candidates were derived are involved in cancer-related processes. Thus, they may represent novel therapeutic targets for this aggressive tumor subtype. PMID:22309216

  9. Identification of sildenafil, tadalafil and vardenafil by gas chromatography-mass spectrometry on short capillary column.

    PubMed

    Man, Che Nin; Nor, Noorjuliana Md; Lajis, Razak; Harn, Gam Lay

    2009-11-20

    Sildenafil and its analogues (tadalafil and vardenafil) are phosphodiesterase type 5 inhibitors used in the treatment of male erectile dysfunction. Some dietary supplements, herbal preparations and food products which claim to enhance male sexual function have been found to be adulterated with these drugs. In this study, a gas chromatograph-mass spectrometer (GC-MS) assay was developed for identification of the drugs. In addition to good and short chromatographic separation that can be achieved within 6 min by using a short 10 m capillary column, no prior sample clean-up before GC-MS analysis was required, thus making this assay a cost saving and rapid method. Furthermore, the assay is specific as the identification of sildenafil, tadalafil and vardenafil were done by detection of molecular ions; m/z 474, 389 and 488, [corrected] respectively, and several other characteristic ions resulted from the mass fragmentation of individual molecules. Using our currently developed assay, sildenafil and its analogues were successfully identified in food and herbal matrices. PMID:19853256

  10. [Determination of dioxins by gas chromatography-mass spectrometry coupled with large volume injection].

    PubMed

    Wang, Yawei; Zhang, Qinghua; Jiang, Guibin; He, Qing

    2007-01-01

    The common analytical instrument for dioxin analysis/determination is gas chromatograph (GC) coupled with an electron capture detector (ECD), a flame ionization detector (FID), and a mass spectrometer (MS) , etc. Generally, since the concentration levels in environmental samples are pg/g or pg/L, it requires a very high resolution and sensitivity for the analytical system. To solve the problem one way is to increase the amount of a sample, however, which can significantly increase the pretreatment work load. The other way is to increase the injection volume. In this paper, a method for dioxin determination was developed using GC-MS coupled with the large volume injection (LVI). Under the condition of maintaining the same amount of solute, the comparison was studied for the changes of peak areas and peak widths by the injection of different volumes from 1 to 100 microL. The results showed that the peak area and peak width did not have obvious changes, and the separation performance was not affected compared with the traditional split/splitless injection. The detection limits obtained are improved by 1 - 2 orders of magnitude over those using split/splitless injections. Once the operation conditions are optimized, LVI is more flexible in handling samples of wide concentration ranges than the traditional split/splitless inlet approach. PMID:17432569

  11. Advances and Challenges in Liquid Chromatography-Mass Spectrometry-Based Proteomics Profiling for Clinical Applications

    SciTech Connect

    Qian, Weijun; Jacobs, Jon M.; Liu, Tao; Camp, David G.; Smith, Richard D.

    2006-08-01

    The advances in proteomic technologies provide tremendous opportunities for applying these technologies in biomarker-related clinical applications; however, the unique characteristics of human biofluids such as high dynamic range in protein abundances and extreme complexity of human proteomes present tremendous challenges for current analytical technologies. In this review, we focus on summarizing the recent advances in LC-MS based proteomic profiling and its applications in clinical proteomics as well as the major challenges for implementing these technologies for more effective biomarker discovery. Over the last few years, tremendous efforts have been directed towards the development of more effective approaches for characterizing the human plasma/serum and other biofluid proteomes. The developments in immunodepletion and various fractionation approaches in combination with much improved LC-MS platforms have enabled the profiling of the plasma proteome with much greater dynamic range of coverage, allowing many proteins at low ng/mL levels being confidently identified. Despite the significant advances and efforts, the dynamic range of measurements or extent of proteome coverage, the confidence of peptide/protein identification, the accuracy of quantitation, the throughput of analysis, and the robustness of the present instrumentation are still among the major challenges for implementation of a proteomic profiling platform suitable for efficient clinical applications.

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

    PubMed

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

    2007-05-01

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

  13. Nanoscale-supported heteropoly acid as a new fiber coating for solid-phase microextraction coupled with gas chromatography-mass spectrometry.

    PubMed

    Abolghasemi, Mir Mahdi; Hassani, Sona; Rafiee, Ezzat; Yousefi, Vahid

    2015-02-13

    In the present study, 12-tungstophosphoric (PW) acid as heteropoly acid, supported on silica-coated ?-Fe2O3 nanoparticles (NPs), was used as a new fiber coating for solid-phase microextraction (SPME). The ?-Fe2O3@SiO2-PW nanocomposite with high surface area was synthesized and characterized by SEM and FT-IR. The prepared nanocomposite was immobilized on a stainless steel wire for fabrication of the SPME fiber. The fiber was evaluated for the extraction of some phenolic compounds (PCs) from water sample in combination with gas chromatography-mass spectrometry (GC-MS). A one-at-a-time optimization strategy was applied for optimizing the important extraction parameters such as extraction temperature, extraction time, ionic strength, stirring rate, pH, and desorption temperature and time. In optimum conditions, the repeatability for one fiber (n=3), expressed as relative standard deviation (R.S.D. %), was between 4.8% and 9.6% for the test compounds. The detection limits for the studied compounds were between 0.004 and 0.05 pg mL(-1). The developed method offers the advantage of being simple to use, with shorter analysis time, lower cost of equipment, thermal stability of fiber and high relative recovery in comparison to conventional methods of analysis. PMID:25618361

  14. A high-throughput multivariate optimization for the simultaneous enantioseparation and detection of barbiturates in micellar electrokinetic chromatography-mass spectrometry (MEKC-MS)

    PubMed Central

    Wang, Bin; He, Jun; Shamsi, Shahab A.

    2011-01-01

    The R- and S-configurations of barbiturates display differences in potency and biological activity. In this study, multivariate micellar electrokinetic chromatography-mass spectrometry (MEKC-MS) approach for the simultaneous analysis of three chiral barbiturates (mephobarbital, pentobarbital, and secobarbital) is developed using a polymeric chiral surfactant. After screening eleven amino acid polymeric surfactants, polysodium N-undecenoxycarbonyl-L-isoleucinate (poly-L-SUCIL) was found to be the best chiral selector. The multivariate central composite design (CCD) is used to optimize the chiral resolution, decrease the total analysis time, and improve the ESI-MS signal-to-noise (S/N) ratio. In the preliminary set of experiments, the ranges of the factors investigated in the multivariate approaches are determined. Next, the CCD design is conducted to determine the best overall chiral resolution with shortest possible run times. This optimization resulted in simultaneous enantioseparation in less than 32 minutes of all three barbiturates with 3–5 fold higher sensitivity by MS compared to UV detection. The adequacy of the multivariate model is validated by three replicate experimental runs at the predicted optimum conditions. The predicted results of MEKC-MS are found to be in good agreement with the experimental data for migration times, resolution and S/N ratio. The optimized method provided good results in terms of linearity and recovery values of chiral barbiturates spiked in human serum after solid phase extraction procedure. PMID:20819283

  15. An investigation of the antidepressant action of xiaoyaosan in rats using ultra performance liquid chromatography-mass spectrometry combined with metabonomics.

    PubMed

    Gao, Xiao-Xia; Cui, Jie; Zheng, Xing-Yu; Li, Zhen-Yu; Choi, Young-Hae; Zhou, Yu-Zhi; Tian, Jun-Sheng; Xing, Jie; Tan, Xiao-Jie; Du, Guan-Hua; Qin, Xue-Mei

    2013-07-01

    A rapid, highly sensitive, and selective method was applied in a non-invasive way to investigate the antidepressant action of Xiaoyaosan (XYS) using ultra performance liquid chromatography-mass spectrometry (UPLC-MS) and chemometrics. Many significantly altered metabolites were used to explain the mechanism. Venlafaxine HCl and fluoxetine HCl were used as chemical positive control drugs with a relatively clear mechanism of action to evaluate the efficiency and to predict the mechanism of action of XYS. Urine obtained from rats subjected to chronic unpredictable mild stress (CUMS) was analyzed by UPLC-MS. Distinct changes in the pattern of metabolites in the rat urine after CUMS production and drug intervention were observed using partial least squares-discriminant analysis. The results of behavioral tests and multivariate analysis showed that CUMS was successfully reproduced, and a moderate-dose XYS produced significant therapeutic effects in the rodent model, equivalent to those of the positive control drugs, venlafaxine HCl and fluoxetine HCl. Metabolites with significant changes induced by CUMS were identified, and 17 biomarker candidates for stress and drug intervention were identified. The therapeutic effect of XYS on depression may involve regulation of the dysfunctions of energy metabolism, amino acid metabolism, and gut microflora changes. Metabonomic methods are valuable tools for measuring efficacy and mechanisms of action in the study of traditional Chinese medicines. PMID:22975930

  16. Signature-discovery approach for sample matching of a nerve-agent precursor using liquid chromatography-mass spectrometry, XCMS, and chemometrics.

    PubMed

    Fraga, Carlos G; Clowers, Brian H; Moore, Ronald J; Zink, Erika M

    2010-05-15

    This report demonstrates the use of bioinformatic and chemometric tools on liquid chromatography-mass spectrometry (LC-MS) data for the discovery of trace forensic signatures for sample matching of ten stocks of the nerve-agent precursor known as methylphosphonic dichloride (dichlor). XCMS, a software tool primarily used in bioinformatics, was used to comprehensively search and find candidate LC-MS peaks in a known set of dichlor samples. These candidate peaks were down selected to a group of 34 impurity peaks. Hierarchal cluster analysis and factor analysis demonstrated the potential of these 34 impurities peaks for matching samples based on their stock source. Only one pair of dichlor stocks was not differentiated from one another. An acceptable chemometric approach for sample matching was determined to be variance scaling and signal averaging of normalized duplicate impurity profiles prior to classification by K-nearest neighbors. Using this approach, a test set of seven dichlor samples were all correctly matched to their source stock. The sample preparation and LC-MS method permitted the detection of dichlor impurities quantitatively estimated to be in the parts-per-trillion (w/w). The detection of a common impurity in all dichlor stocks that were synthesized over a 14-year period and by different manufacturers was an unexpected discovery. Our described signature-discovery approach should be useful in the development of a forensic capability to assist investigations following chemical attacks. PMID:20405949

  17. Optimization of headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry for detecting methoxyphenolic compounds in pu-erh tea.

    PubMed

    Du, Liping; Wang, Chao; Li, Jianxun; Xiao, Dongguang; Li, Changwen; Xu, Yongquan

    2013-01-23

    A method based on headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry was developed for the analysis of volatile methoxyphenolic compounds in pu-erh tea. Six fibers with different polarities were initially evaluated. The 75 ?m carboxen/polydimethylsiloxane fiber exhibited the highest extraction efficiency and was selected for further optimization. A Plackett-Burman design was used to screen for the brewing proportion of tea and water, amount of pu-erh tea, ionic strength, extraction time, extraction temperature, desorption time, rate of agitation, and equilibrium time. A Box-Behnken design was then applied to optimize the significant factors. Under optimal conditions, the proposed method affords a wide range of linearity, high linear regression coefficients (0.996-0.999), less than 9.0% repeatability of relative standard deviation, and limits of detection ranging from 2.31 to 21.80 ng/g. The proposed method has satisfactory accuracy, with recoveries of 79.08-113.9%. This method was successfully applied for the analysis of pu-erh tea samples. PMID:23268690

  18. Headspace solid-phase microextraction gas chromatography-mass spectrometry determination of volatile compounds in different varieties of African star apple fruit (Chrysophillum albidum).

    PubMed

    Lasekan, Ola; Khatib, Alfi; Juhari, Hanisah; Patiram, Parveen; Lasekan, Seye

    2013-12-01

    The volatile compounds in four selected African star apple fruit (Chrysophyllum albidum) varieties were isolated and identified using the headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). A total of 59 compounds were identified. Application of the aroma extract dilution analysis (AEDA) to the aroma distillates from the fruits revealed 45 odour-active compounds in the flavour dilution (FD) factor range of 4-128. Among them, the highest odour activities (FD factors) were determined for methylhexanoate, acetophenone and ethyl dodecanoate. Moreover, aroma lipophilicity appears to reflect molecular conformation. Further analysis of the similarities and differences between the fruit varieties in terms of the key odourants by the application of PLS-DA and PLS-regression coefficient showed strong positive correlation between the very sweet/sweet varieties and 10 key odourants. The odourants included ethyl acetate, acetyl methyl carbinol, methylhexanoate, sabinene, p-cymene, methylbenzoate, ethylbenzoate, geraniol, cis-?-bergomotene, acetophenone, and ethyl dodecanoate. PMID:23870932

  19. Determination of the herbicide glyphosate and its metabolite in biological specimens by gas chromatography-mass spectrometry. A case of poisoning by roundup herbicide.

    PubMed

    Hori, Yasushi; Fujisawa, Manami; Shimada, Kenji; Hirose, Yasuo

    2003-04-01

    In Japan, poisonings by the glyphosate (GLYP)-containing herbicide Roundup and the gluphosinate (GLUF)-based herbicide BASTA have been increasing since about 1987. We applied the gas chromatography-mass spectrometry (GC-MS) method of analysis, on which we have already reported in regard to the determination of the blood serum level of GLUF and its metabolite, for the determination of serum and urinary levels of GLYP and its metabolite aminomethyl phosphonic acid (AMPA). Derivatization using N-methyl-N-(tert-butyldimethylsilyl) trifluoroacetamide was completed at a temperature of 80 degrees C after 30 min, and the detection limit of GLYP was 10 pg using m/z 454 and that of AMPA was 1 pg using m/z 396. The full mass spectra of 100 pg GLYP and of 10 pg AMPA were obtained easily. In extractions for which the Isolute HAX cartridge was employed, the mean recovery rate of GLYP and AMPA added to serum to yield concentrations of 10-0.1 microg/mL (n = 5) was 91.6 +/- 10.6% (or better), whereas that of GLYP and AMPA added to urine to yield concentrations of 100-1.0 microg/mL (n = 10) was 93.3 +/- 6.6% (or better), both of which were good rates. Also, using this method of analysis, the presence of GLYP was identified in the full mass spectra obtained from the serum of a patient who may or may not have ingested Roundup. PMID:12731658

  20. Determination of aromatic amines in human urine using comprehensive multi-dimensional gas chromatography mass spectrometry (GCxGC-qMS).

    PubMed

    Lamani, Xolelwa; Horst, Simeon; Zimmermann, Thomas; Schmidt, Torsten C

    2015-01-01

    Aromatic amines are an important class of harmful components of cigarette smoke. Nevertheless, only few of them have been reported to occur in urine, which raises questions on the fate of these compounds in the human body. Here we report on the results of a new analytical method, in situ derivatization solid phase microextraction (SPME) multi-dimensional gas chromatography mass spectrometry (GCxGC-qMS), that allows for a comprehensive fingerprint analysis of the substance class in complex matrices. Due to the high polarity of amino compounds, the complex urine matrix and prevalence of conjugated anilines, pretreatment steps such as acidic hydrolysis, liquid-liquid extraction (LLE), and derivatization of amines to their corresponding aromatic iodine compounds are necessary. Prior to detection, the derivatives were enriched by headspace SPME with the extraction efficiency of the SPME fiber ranging between 65 % and 85 %. The measurements were carried out in full scan mode with conservatively estimated limits of detection (LOD) in the range of several ng/L and relative standard deviation (RSD) less than 20 %. More than 150 aromatic amines have been identified in the urine of a smoking person, including alkylated and halogenated amines as well as substituted naphthylamines. Also in the urine of a non-smoker, a number of aromatic amines have been identified, which suggests that the detection of biomarkers in urine samples using a more comprehensive analysis as detailed in this report may be essential to complement the approach of the use of classic biomarkers. PMID:25142049