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

    PubMed

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

    2012-09-21

    Twenty-six resins from six botanical sources belonging to the class Magnoliopsida were compared based on gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry data. The extracts were analysed by GC after silylation and by reversed phase LC combined with atmospheric pressure photoionisation (APPI) mass spectrometry. The chromatograms were re-organized in data matrices, where each sample was represented by a single column comprising 2755 observations (intensity, time, m/z) in GC-MS and 360 observations in LC-MS. A simple comparison of resin fingerprints was attempted by organizing data according to a three dimensional bubble chart (retention time against m/z where each point was a bubble which size represented the ion intensity) where it is possible to easily superimpose the fingerprints. Thus the common and different species can be easily observed enabling to classify the resins. Hierarchical cluster analysis based on characteristics of GC-MS and LC-MS profiles affords a complete description of the classes of the resins and shows that 26 resins are divided into five main clusters Commiphora mukul, Daniella oliveri, Gardenia gummifera, Canarium madagascariensis, Boswellia dalzielii and Boswellia serrata, respectively. In conclusion, the proposed method has been applied to three other resinous samples from the Burseraceae family to evaluate their alteration state. PMID:22885042

  3. Targeted analysis of glycomics liquid chromatography/mass spectrometry data

    PubMed Central

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

    2012-01-01

    Hydrophilic interaction chromatography (HILIC) liquid chromatography/mass spectrometry (LC/MS) is appropriate for all native and reductively aminated glycan classes. HILIC carries the advantage that retention times (RTs) vary predictably according to oligosaccharide composition. Chromatographic conditions are compatible with sensitive and reproducible glycomics analysis of large numbers of samples. The data are extremely useful for quantitative profiling of glycans expressed in biological tissues. With these analytical developments, the rate limiting factor for widespread use of HILIC LC/MS in glycomics is the analysis of the data. In order to eliminate this problem, a Java-based open source software tool, Manatee, was developed for targeted analysis of HILIC LC/MS glycan data sets. This tool uses user-defined lists of compositions that specify the glycan chemical space in a given biological context. The program accepts high resolution LC/MS data using the public mzXML format and is capable of processing a large data file in a few minutes on a standard desktop computer. The program allows mining of HILIC LC/MS data with an output compatible with multivariate statistical analysis. It is envisaged that the Manatee tool will complement more computationally intensive LC/MS processing tools based on deconvolution and deisotoping of LC/MS data. The capabilities of the tool were demonstrated using a set of HILIC LC/MS data on organ-specific heparan sulfates. PMID:20953780

  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. AN EPA MANUAL FOR ORGANICS ANALYSIS USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY

    EPA Science Inventory

    This procedural manual defines the areas of applicability of gas chromatography-mass spectrometry in environmental analysis. The manual includes sample preparation methods specifically adapted to this measurement technique, data processing and interpretation methods, quality cont...

  6. INTERLABORATORY COMPARISON OF THERMOSPRAY AND PARTICLE BEAM LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY INTERFACES: EVALUATION OF A CHLORINATED PHENOXY ACID HERBICIDE LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY ANALYSIS METHOD

    EPA Science Inventory

    Seven laboratories participated in an interlaboratory evaluation of a liquid chromatography/mass spectrometry (LC/MS) method for the analysis of 10 chlorinated phenoxy acid herbicides. The focus of this evaluation was to test the intercomparability of LC/MS data obtained from two...

  7. ANALYSIS OF CHLORINATED HERBICIDES BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY

    EPA Science Inventory

    A method that uses high performance liquid chromatography/mass spectrometry (HPLC/MS) for the analysis of chlorinated phenoxyacid herbicides is described. uring method development different techniques were used to increase both the sensitivity and the specificity of thermospray H...

  8. Applications of liquid chromatography-mass spectrometry for food analysis.

    PubMed

    Di Stefano, Vita; Avellone, Giuseppe; Bongiorno, David; Cunsolo, Vincenzo; Muccilli, Vera; Sforza, Stefano; Dossena, Arnaldo; Drahos, László; Vékey, Károly

    2012-10-12

    HPLC-MS applications in the agrifood sector are among the fastest developing fields in science and industry. The present tutorial mini-review briefly describes this analytical methodology: HPLC, UHPLC, nano-HPLC on one hand, mass spectrometry (MS) and tandem mass spectrometry (MS/MS) on the other hand. Analytical results are grouped together based on the type of chemicals analyzed (lipids, carbohydrates, glycoproteins, vitamins, flavonoids, mycotoxins, pesticides, allergens and food additives). Results are also shown for various types of food (ham, cheese, milk, cereals, olive oil and wines). Although it is not an exhaustive list, it illustrates the main current directions of applications. Finally, one of the most important features, the characterization of food quality (including problems of authentication and adulteration) is discussed, together with a future outlook on future directions. PMID:22560344

  9. Supercritical fluid chromatography-mass spectrometry for chemical analysis.

    PubMed

    Li, Fangbiao; Hsieh, Yunsheng

    2008-05-01

    Chromatography with a supercritical fluid as the mobile phase was suggested more than four decades ago (Klesper, E., Corwin, A. H., Turner, D. A., J. Org. Chem. 1962, 27, 700-701). Supercritical fluid chromatography (SFC) is basically a hybrid of GC and LC that eases the resolution of a mixture of compounds not conveniently resolved by either GC or LC. The mobile phases for SFC have low viscosities and high diffusion coefficients compared to those for HPLC and allow for high efficiency separations. SFC uses supercritical fluid as the mobile phase, polar organic solvents as the modifiers in conjunction with acidic/basic compounds as additives to run the chromatographic process like in HPLC. In many applications, SFC-based methods are advantageous over HPLC-based methods as a separation tool in terms of efficiency and economical impact perspectives. Today, the availability of commercial hardware and API interfaces with a mass spectrometer makes SFC even more widely applicable for chemical analysis in many research fields. This review summarizes a variety of novel SFC-MS methods for chemical analysis that have been reported in the peer-reviewed publications. PMID:18366029

  10. Acetic acid improves the sensitivity of theophylline analysis by gas chromatography-mass spectrometry.

    PubMed

    Saka, Kanju; Uemura, Koichi; Shintani-Ishida, Kaori; Yoshida, Ken-Ichi

    2007-02-01

    In the analysis of theophylline by gas chromatography-mass spectrometry (GC-MS), we found that the addition of acetic acid to the solvent (ethyl acetate) decreased the adsorption of theophylline to the glass wool packed into the inlet liner. The addition of acetic acid to ethyl acetate improved the sensitivity for theophylline (optimum concentration of 3%). This simple and sensitive method without derivatization can be applied to the quantification of theophylline in serum samples in clinical and toxicological practice. PMID:17011247

  11. Analysis of volatile organic compounds in groundwater samples by gas chromatography-mass spectrometry

    SciTech Connect

    Bernhardt, J.

    1995-08-23

    The Savannah River Site contains approximately 1500 monitoring wells from which groundwater samples are collected. Many of these samples are sent off-site for various analyses, including the determination of trace volatile organic compounds (VOCs). This report describes accomplishments that have been made during the past year which will ultimately allow VOC analysis to be performed on-site using gas chromatography-mass spectrometry. Through the use of the on-site approach, it is expected that there will be a substantial cost savings. This approach will also provide split-sample analysis capability which can serve as a quality control measure for off-site analysis.

  12. Analysis of limonoid glucosides from citrus by electrospray ionization liquid chromatography-mass spectrometry.

    PubMed

    Schoch, T K; Manners, G D; Hasegawa, S

    2001-03-01

    An electrospray ionization liquid chromatography-mass spectrometry (ESI-LC-MS) method for the detection and quantitation of limonoid glucosides has been developed. Negative ions [M - H(+)](-) characteristic of six limonoid glucosides can be detected and quantified from selected ion monitoring chromatograms using carminic acid as an internal standard. The described method has been applied to the analysis of limonoid glucoside content in various liquid and solid Citrus spp. samples as well as complex mixtures of partially purified limonoid glucosides. Rapid and sensitive qualitative screening of samples for limonoid glucosides can also be accomplished with slight modifications of the method. PMID:11312819

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

    PubMed

    Czyżewska, Urszula; Konończuk, Joanna; Teul, Joanna; Drągowski, Paweł; Pawlak-Morka, Renata; Surażyński, 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

  14. Analysis of cooking oil fumes by ultraviolet spectrometry and gas chromatography-mass spectrometry.

    PubMed

    Zhu, X; Wang, K; Zhu, J; Koga, M

    2001-10-01

    This paper investigated the components, especially aldehydes, in the fume condensates from four kinds of cooking oil using ultraviolet (UV) spectrometry and gas chromatography-mass spectrometry (GC-MS). It was observed that there was a great change of the UV absorption spectra from the results of the unheated oil to the results of the fume after heat treatment (190-200, 230-240, and 270-280 degrees C). There was a strong peak within the wavelength range of 260-270 nm in each condensate sample. From the GC-MS results, it was tentatively deduced that there were some 2,4-dialkylenaldehydes and other conjugated compounds in the condensates. The results showed there were large amounts of hexanal and 2-heptenal in the cooking oil fume and that the total aldehyde peak areas of the condensates from four kinds of oil were around 30-50% of the total peak area at 270-280 degrees C. PMID:11600023

  15. High-speed, low-pressure gas chromatography-mass spectrometry for essential oil analysis.

    PubMed

    Poynter, Samuel D H; Shellie, Robert A

    2008-07-18

    Analysis of parsley and fennel essential oils was performed by using low-pressure gas chromatography-mass spectrometry (GC-MS). The low-pressure instrument configuration was achieved by fitting a GC-MS instrument with a 530microm I.D. capillary column and an appropriate capillary restrictor at the inlet of the column. Comparison of the performance of the low-pressure GC-MS setup was made with fast GC-MS using a narrow-bore capillary column. By comparing the two approaches side-by-side the benefits of low-pressure GC-MS for characterisation of moderately complex essential oils comprising less than 50 detectable components can be fully appreciated. Although efficiency is sacrificed, the improved sample capacity of the 530microm I.D. column leads to higher peak intensities and in-turn better mass spectral library matching thus providing highly satisfactory results. PMID:18406412

  16. Multivariate analysis of progressive thermal desorption coupled gas chromatography-mass spectrometry.

    SciTech Connect

    Van Benthem, Mark Hilary; Mowry, Curtis Dale; Kotula, Paul Gabriel; Borek, Theodore Thaddeus, III

    2010-09-01

    Thermal decomposition of poly dimethyl siloxane compounds, Sylgard{reg_sign} 184 and 186, were examined using thermal desorption coupled gas chromatography-mass spectrometry (TD/GC-MS) and multivariate analysis. This work describes a method of producing multiway data using a stepped thermal desorption. The technique involves sequentially heating a sample of the material of interest with subsequent analysis in a commercial GC/MS system. The decomposition chromatograms were analyzed using multivariate analysis tools including principal component analysis (PCA), factor rotation employing the varimax criterion, and multivariate curve resolution. The results of the analysis show seven components related to offgassing of various fractions of siloxanes that vary as a function of temperature. Thermal desorption coupled with gas chromatography-mass spectrometry (TD/GC-MS) is a powerful analytical technique for analyzing chemical mixtures. It has great potential in numerous analytic areas including materials analysis, sports medicine, in the detection of designer drugs; and biological research for metabolomics. Data analysis is complicated, far from automated and can result in high false positive or false negative rates. We have demonstrated a step-wise TD/GC-MS technique that removes more volatile compounds from a sample before extracting the less volatile compounds. This creates an additional dimension of separation before the GC column, while simultaneously generating three-way data. Sandia's proven multivariate analysis methods, when applied to these data, have several advantages over current commercial options. It also has demonstrated potential for success in finding and enabling identification of trace compounds. Several challenges remain, however, including understanding the sources of noise in the data, outlier detection, improving the data pretreatment and analysis methods, developing a software tool for ease of use by the chemist, and demonstrating our belief that this multivariate analysis will enable superior differentiation capabilities. In addition, noise and system artifacts challenge the analysis of GC-MS data collected on lower cost equipment, ubiquitous in commercial laboratories. This research has the potential to affect many areas of analytical chemistry including materials analysis, medical testing, and environmental surveillance. It could also provide a method to measure adsorption parameters for chemical interactions on various surfaces by measuring desorption as a function of temperature for mixtures. We have presented results of a novel method for examining offgas products of a common PDMS material. Our method involves utilizing a stepped TD/GC-MS data acquisition scheme that may be almost totally automated, coupled with multivariate analysis schemes. This method of data generation and analysis can be applied to a number of materials aging and thermal degradation studies.

  17. Issues pertaining to the analysis of buprenorphine and its metabolites by gas chromatography-mass spectrometry.

    PubMed

    Wang, Yu-Shan; Lin, Dong-Liang; Yang, Shu-Ching; Wu, Meng-Yan; Liu, Ray H; Su, Lien-Wen; Cheng, Pai-Sheng; Liu, Chiareiy; Fuh, Ming-Ren

    2010-03-01

    "Substitution therapy" and the use of buprenorphine (B) as an agent for treating heroin addiction continue to gain acceptance and have recently been implemented in Taiwan. Mature and widely utilized gas chromatography-mass spectrometry (GC-MS) technology can complement the low cost and highly sensitive immunoassay (IA) approach to facilitate the implementation of analytical tasks supporting compliance monitoring and pharmacokinetic/pharmacogenetic studies. Issues critical to GC-MS analysis of B and norbuprenorphine (NB) (free and as glucuronides), including extraction, hydrolysis, derivatization, and quantitation approaches were studied, followed by comparing the resulting data against those derived from IA and two types of liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. Commercial solid-phase extraction devices, highly effective for recovering all metabolites, may not be suitable for the analysis of free B and NB; acetyl-derivatization products exhibit the most favorable chromatographic, ion intensity, and cross-contribution characteristics for GC-MS analysis. Evaluation of IA, GC-MS, and LC-MS/MS data obtained in three laboratories has proven the 2-aliquot GC-MS protocol effective for the determination of free B and NB and their glucuronides. PMID:20122691

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

    PubMed Central

    Suzuki, Shigeru

    2014-01-01

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

  19. DETERMINATION OF VOLATILE ORGANIC COMPOUNDS IN SOILS USING EQUILIBRIUM HEADSPACE ANALYSIS AND CAPILLARY COLUMN GAS CHROMATOGRAPHY/MASS SPECTROMETRY

    EPA Science Inventory

    Existing methods for determination of volatile organic compounds (VOCs) in soil matrices using the purge and trap technique with gas chromatography/mass spectrometry (GC/MS) have several problems, which include preserving sample integrity from collection to analysis and efficient...

  20. ANALYSIS OF TRACE-LEVEL ORGANIC COMBUSTION PROCESS EMISSIONS USING NOVEL MULTIDIMENSIONAL GAS CHROMATOGRAPHY-MASS SPECTROMETRY PROCEDURES

    EPA Science Inventory

    The paper discusses the analysis of trace-level organic combustion process emissions using novel multidimensional gas chromatography-mass spectrometry (MDGC-MS) procedures. It outlines the application of the technique through the analyses of various incinerator effluent and produ...

  1. Recent trends in the liquid chromatography-mass spectrometry analysis of organic contaminants in environmental samples.

    PubMed

    Petrovic, Mira; Farré, Marinella; de Alda, Miren Lopez; Perez, Sandra; Postigo, Cristina; Köck, Marianne; Radjenovic, Jelena; Gros, Merixell; Barcelo, Damia

    2010-06-18

    An overview of liquid chromatography-mass spectrometry methods used for the determination of trace organic contaminants in environmental samples is presented. Among the organic contaminants the focus is given on five groups of emerging contaminants that raised most concern as environmental contaminants and therefore attracted attention of a research community: pharmaceuticals, drugs of abuse, polar pesticides, perfluorinated compounds and nanoparticles. Various aspects of current LC-MS methodology, using tandem and hybrid MS instruments, including sample preparation, are discussed. PMID:20334864

  2. 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.

  3. 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.

  4. [Separation of tannins in Rhubarb and its analysis by high performance liquid chromatography-mass spectrometry].

    PubMed

    Ding, Mingyu; Ni, Weiwei

    2004-11-01

    In order to investigate the pharmaceutical actions of rhubarb, a method for extracting, separating and analyzing the tannin components in rhubarb was studied. At first, a procedure for the group separation of tannins from the water-ethanol extract of rhubarb was established based on the formation of tannins-caffein precipitation. Then, a high performance liquid chromatographic (HPLC) method for the analysis of tannins in rhubarb was developed. This HPLC method is based on a reversed-phase C18 column and polar mobile-phase such as water and methanol with gradient elution, and the tannins can be well separated. Finally, the identification of the tannin components in rhubarb was carried out by high performance liquid chromatography-mass spectrometry (HPLC-MS). The structures of the main tannin components (gallic acid, catechin, the dimer, trimer, tetramer and pentamer of catechin) in rhubarb are suggested. The fragmentation laws of the tannin components are summarized. In comparing with previous methods, it is simple and without the interference of co-existed compounds. PMID:15807111

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

    PubMed Central

    2014-01-01

    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-μm or 2.6–2.8-μm (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

  6. 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

  7. 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.

  8. Assessment of oil weathering by gas chromatography-mass spectrometry, time warping and principal component analysis.

    PubMed

    Malmquist, Linus M V; Olsen, Rasmus R; Hansen, Asger B; Andersen, Ole; Christensen, Jan H

    2007-09-14

    Detailed characterization and understanding of oil weathering at the molecular level is an essential part of tiered approaches for forensic oil spill identification, for risk assessment of terrestrial and marine oil spills, and for evaluating effects of bioremediation initiatives. Here, a chemometric-based method is applied to data from two in vitro experiments in order to distinguish the effects of evaporation and dissolution processes on oil composition. The potential of the method for obtaining detailed chemical information of the effects from evaporation and dissolution processes, to determine weathering state and to distinguish between various weathering processes is investigated and discussed. The method is based on comprehensive and objective chromatographic data processing followed by principal component analysis (PCA) of concatenated sections of gas chromatography-mass spectrometry chromatograms containing homologue series of n-alkanes (m/z 85) and alkyltoluenes (m/z 105). The PCA model based solely on in vitro samples and validated by samples from an authentic marine oil spill gives a detailed description of the temporal changes in n-alkane and alkyltoluene compositions. The PCA model is able to distinguish the two physical weathering processes both with respect to removal rate and relative changes. The model shows that evaporation has a large impact on both the alkyltoluenes and on the n-alkanes (e.g., nC-18 is completely removed after 192 days of in vitro evaporation). Dissolution, however, is shown to be a much slower process for weathering of heavy fuel oils with only limited impact on the alkyltoluenes, and no effects on the n-alkane distribution. PMID:17669412

  9. [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

  10. DIRECT ANALYSIS OF RAT BILE FOR ACETAMINOPHEN AND TWO OF ITS CONJUGATED METABOLITES VIA THERMOSPRAY LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY

    EPA Science Inventory

    Bile from rats treated with acetaminophen was analyzed by direct injection onto a thermospray liquid chromatography/mass spectrometry system. Two conjugated metabolites of acetaminophen were separated by the high-pressure liquid chromatographic system and analyzed by mass spectro...

  11. Isolation and derivatization of plasma taurine for stable isotope analysis by gas chromatography-mass spectrometry

    SciTech Connect

    Irving, C.S.; Klein, P.D.

    1980-09-01

    A method for the isolation and derivatization of plasma taurine is described that allows stable isotope determinations of taurine to be made by gas chromatography-mass spectrometry. The isolation procedure can be applied to 0.1 ml of plasma; the recovery of plasma taurine was 70 to 80%. For gc separation, taurine was converted to its dimethylaminomethylene methyl ester derivative which could not be detected by hydrogen flame ionization, but could be monitored readily by NH/sub 3/ chemical ionization mass spectrometry. The derivatization reaction occurred partially on-column and required optimization of injection conditions. Using stable isotope ratiometry multiple ion detection, (M + 2 + H)/sup +//(M + H)/sup +/ ion ratio of natural abundance taurine was determined with a standard deviation of less than +-0.07% of the ratio. The (1,2-/sup 13/C)taurine/taurine mole ratios of standard mixtures could be accurately determined to 0.001. This stable isotope gc-ms method is suitable for studying the plasma kinetics of (1,2-/sup 13/C)taurine in infants who are at risk with respect to taurine depletion.

  12. 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

  13. Analysis of volatile compounds of Malaysian Tualang (Koompassia excelsa) honey using gas chromatography mass spectrometry.

    PubMed

    Nurul Syazana, M S; Gan, S H; Halim, A S; Shah, Nurul Syazana Mohamad; Gan, Siew Hua; Sukari, Halim Ahmad

    2013-01-01

    The constituents of honey's volatile compounds depend on the nectar source and differ depending on the place of origin. To date, the volatile constituents of Tualang honey have never been investigated. The objective of this study was to analyze the volatile compounds in local Malaysian Tualang honey. A continuous extraction of Tualang honey using five organic solvents was carried out starting from non-polar to polar solvents and the extracted samples were analysed using gas chromatography-mass spectrometry (GC-MS). Overall, 35 volatile compounds were detected. Hydrocarbons constitute 58.5% of the composition of Tualang honey. Other classes of chemical compounds detected included acids, aldehydes, alcohols, ketones, terpenes, furans and a miscellaneous group. Methanol yielded the highest number of extracted compounds such as acids and 5-(Hydroxymethyl) furfural (HMF). This is the first study to describe the volatile compounds in Tualang honey. The use of a simple one tube, stepwise, non-thermal liquid-liquid extraction of honey is a advantageous as it prevents sample loss. Further research to test the clinical benefits of these volatile compounds is recommended. PMID:24146441

  14. Comparative Analysis of Mass Spectral Matching-based Compound Identification in Gas Chromatography Mass Spectrometry

    PubMed Central

    Koo, Imhoi; Kim, Seongho; Zhang, Xiang

    2013-01-01

    Compound identification in gas chromatographymass spectrometry (GC-MS) is usually achieved by matching query spectra to spectra present in a reference library. Although several spectral similarity measures have been developed and compared using a small reference library, it still remains unknown how the relationship between the spectral similarity measure and the size of reference library affects on the identification accuracy as well as the optimal weight factor. We used three reference libraries to investigate the dependency of the optimal weight factor, spectral similarity measure and the size of reference library. Our study demonstrated that the optimal weight factor depends on not only spectral similarity measure but also the size of reference library. The mixture semi-partial correlation measure outperforms all existing spectral similarity measures in all tested reference libraries, in spite of the computational expense. Furthermore, the accuracy of compound identification using a larger reference library in future is estimated by varying the size of reference library. Simulation study indicates that the mixture semi-partial correlation measure will have the best performance with the increase of reference library in future. PMID:23726352

  15. Analysis of endogenous aldehydes in human urine by static headspace gas chromatography-mass spectrometry.

    PubMed

    Serrano, María; Gallego, Mercedes; Silva, Manuel

    2016-03-11

    Endogenous aldehydes (EAs) generated during oxidative stress and cell processes are associated with many pathogenic and toxicogenic processes. The aim of this research was to develop a solvent-free and automated analytical method for the determination of EAs in human urine using a static headspace generator sampler coupled with gas chromatography-mass spectrometry (HS-GC-MS). Twelve significant EAs used as markers of different biochemical and physiological processes, namely short- and medium-chain alkanals, α,β-unsaturated aldehydes and dicarbonyl aldehydes have been selected as target analytes. Human urine samples (no dilution is required) were derivatized with O-2,3,4,5,6-pentafluorobenzylhydroxylamine in alkaline medium (hydrogen carbonate-carbonate buffer, pH 10.3). The HS-GC-MS method developed renders an efficient tool for the sensitive and precise determination of EAs in human urine with limits of detection from 1 to 15ng/L and relative standard deviations, (RSDs) from 6.0 to 7.9%. Average recoveries by enriching urine samples ranged between 92 and 95%. Aldehydes were readily determined at 0.005-50μg/L levels in human urine from healthy subjects, smokers and diabetic adults. PMID:26879451

  16. Direct analysis of oligomeric tackifying resins in rubber compounds by automatic thermal desorption gas chromatography/mass spectrometry

    PubMed

    Kim

    1999-01-01

    Two analytical methods, automatic thermal desorption gas chromatography/mass spectrometry (ATD-GC/MS) and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS), were applied as direct methods for the analysis of oligomeric tackifying resins in a vulcanized rubber. The ATD-GC/MS method, based on discontinuous volatile extraction, was found to be an effective means for direct analysis of the oligomeric tackifying resins contained in a vulcanized rubber. The oligomeric tackifying resins, such as t-octylphenolformaldehyde (TOPF) resin, rosin-modified terpene resin, and cashew resin, could be directly analyzed in vulcanized rubber by ATD-GC/MS. Much simpler total ion chromatograms were obtained by ATD-GC/MS than by flash pyrolysis with a Curie-point pyrolyzer, permitting much easier interpretation. Ions at m/z 206, 135, and 107 were fingerprints in the characteristic mass spectra obtained by ATD-GC/MS for TOPF resin in the vulcanized rubber. 1H-Indene, styrene, and isolongifolene were observed as their characteristic mass spectra in the pyrolyzate of the rosin-modified terpene resin. From the cashew resin, phenol, 3-methylphenol, and 4-(1,1,3, 3-tetramethylbutyl)phenol were obtained as the characteristic pyrolyzates by discontinuous thermal extraction via ATD-GC/MS. Copyright 1999 John Wiley & Sons, Ltd. PMID:10589102

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

    PubMed

    Zábranská, Marie; Vrkoslav, Vladimír; Sobotníková, Jana; Cvačka, 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

  18. The analysis of tire rubber traces collected after braking incidents using Pyrolysis-GasChromatography/Mass Spectrometry.

    PubMed

    Sarkissian, Garry

    2007-09-01

    Automobile tire marks can routinely be found at the scenes of crime, particularly hit-and-run accidents and are left on road surfaces because of sudden braking or the wheels spinning. The tire marks are left due to the friction between the tire rubber and the solid road surface, and do not always demonstrate the tire tread pattern. However, the tire mark will contain traces of the tire. In this study, Pyrolysis Gas Chromatography/Mass Spectrometry was used to analyze 12 tires from different manufacturer's and their traces collected after braking incidents. Tire marks were left on a conglomerate road surface with sudden braking. The samples were pyrolysed without removal of contaminant in a micro-furnace type pyrolyser. Quantitative and qualitative analysis were performed on all the samples. All 12 samples were distinguished from each other. Each of the tire traces were identified as coming from there original source. PMID:17767653

  19. High-throughput and highly sensitive analysis method for polyisoprene in plants by pyrolysis-gas chromatography/mass spectrometry.

    PubMed

    Takeno, Shinya; Bamba, Takeshi; Nakazawa, Yoshihisa; Fukusaki, Eiichiro; Okazawa, Atsushi; Kobayashi, Akio

    2010-01-01

    Natural polyisoprene is a biopolymer consisting of isoprene units (C(5)H(8)) that is used commercially in household, medical, and industrial materials. For the management of natural polyisoprene production, the selection of high-yield polyisoprene-producing trees, and an understanding of polyisoprene biosynthesis, a high-throughput and highly sensitive screening method for the quantification of polyisoprene is required. In this study, we examined pyrolysates from polyisoprenes, polyprenols, carotenoids, ubiquinone (CoQ-10), and sterols by pyrolysis gas chromatography/mass spectrometry (PyGC/MS) and determined that the amounts of isoprene and limonene released from polyprenols and polyisoprenes were dependent upon their molecular weights. Based on these results, we developed a relative quantification method for polyisoprene in leaves by direct analysis of 1 mg of leaves using PyGC/MS. This novel quantification method eliminated extraction steps and can be used in the measurement of polyisoprene contents in Eucommia ulmoides and Hevea brasiliensis. PMID:20057156

  20. Introducing Students to Gas Chromatography-Mass Spectrometry Analysis and Determination of Kerosene Components in a Complex Mixture

    ERIC Educational Resources Information Center

    Pacot, Giselle Mae M.; Lee, Lyn May; Chin, Sung-Tong; Marriott, Philip J.

    2016-01-01

    Gas chromatography-mass spectrometry (GC-MS) and GC-tandem MS (GC-MS/MS) are useful in many separation and characterization procedures. GC-MS is now a common tool in industry and research, and increasingly, GC-MS/MS is applied to the measurement of trace components in complex mixtures. This report describes an upper-level undergraduate experiment…

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

    ERIC Educational Resources Information Center

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

    2016-01-01

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

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

    ERIC Educational Resources Information Center

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

    2016-01-01

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

  3. High Throughput Quantitative Analysis of Serum Proteins Using Glycopeptide Capture and Liquid Chromatography Mass Spectrometry

    SciTech Connect

    Zhang, Hui; Yi, Eugene C.; Li, Xiao-jun; Mallick, Parag; Kelly-Spratt, Karen S.; Masselon, Christophe D.; Camp, David G.; Smith, Richard D.; Kemp, Christopher J.; Aebersold, Reudi

    2005-02-01

    It is expected that the composition of the serum proteome can provide valuable information about the state of the human body in health and disease and that this information can be extracted via quantitative proteomic measurements. Suitable proteomic techniques need to be sensitive, reproducible, and robust to detect potential biomarkers below the level of highly expressed proteins, generate data sets that are comparable between experiments and laboratories, and have high throughput to support statistical studies. Here we report a method for high throughput quantitative analysis of serum proteins. It consists of the selective isolation of peptides that are N-linked glycosylated in the intact protein, the analysis of these now deglycosylated peptides by liquid chromatography electrospray ionization mass spectrometry, and the comparative analysis of the resulting patterns. By focusing selectively on a few formerly N-linked glycopeptides per serum protein, the complexity of the analyte sample is significantly reduced and the sensitivity and throughput of serum proteome analysis are increased compared with the analysis of total tryptic peptides from unfractionated samples. We provide data that document the performance of the method and show that sera from untreated normal mice and genetically identical mice with carcinogen-induced skin cancer can be unambiguously discriminated using unsupervised clustering of the resulting peptide patterns. We further identify, by tandem mass spectrometry, some of the peptides that were consistently elevated in cancer mice compared with their control littermates.

  4. Analysis of 5-hydroxymethylfurfural in foods by gas chromatography-mass spectrometry.

    PubMed

    Teixidó, E; Santos, F J; Puignou, L; Galceran, M T

    2006-11-24

    A new, simple and selective method for the analysis of 5-hydroxymethylfurfural (HMF) in foods by gas chromatography coupled to mass spectrometry (GC-MS) is proposed. Several derivatising procedures based on the formation of an HMF silylated derivative using different reagents were studied. Among the derivatising reagents examined, N,O-bis-trimethylsilyltrifluoroacetamide (BSTFA) provided the best derivatisation yield. Sample clean-up was also optimised, using either liquid-liquid extraction with dichloromethane or solid-phase extraction (SPE) with several commercially available cartridges, and the best results were obtained using ENV+ cartridges. Quality parameters such as day-to-day and run-to-run precision (RSD<10%), linearity (between 25 and 700 ng g(-1)) and detection limit (6 ng g(-1)) were established. This method was successfully applied to the analysis of HMF content in several Spanish food samples from a local market, such as jam, honey, orange juice and bakery products. PMID:17010355

  5. Targeted Chiral Analysis of Bioactive Arachidonic Acid Metabolites Using Liquid-Chromatography-Mass Spectrometry

    PubMed Central

    Mesaros, Clementina; Blair, Ian A.

    2012-01-01

    A complex structurally diverse series of eicosanoids arises from the metabolism of arachidonic acid. The metabolic profile is further complicated by the enantioselectivity of eicosanoid formation and the variety of regioisomers that arise. In order to investigate the metabolism of arachidonic acid in vitro or in vivo, targeted methods are advantageous in order to distinguish between the complex isomeric mixtures that can arise by different metabolic pathways. Over the last several years this targeted approach has become more popular, although there are still relatively few examples where chiral targeted approaches have been employed to directly analyze complex enantiomeric mixtures. To efficiently conduct targeted eicosanoid analyses, LC separations are coupled with collision induced dissociation (CID) and tandem mass spectrometry (MS/MS). Product ion profiles are often diagnostic for particular regioisomers. The highest sensitivity that can be achieved involves the use of selected reaction monitoring/mass spectrometry (SRM/MS); whereas the highest specificity is obtained with an SRM transitions between an intense parent ion, which contains the intact molecule (M) and a structurally significant product ion. This review article provides an overview of arachidonic acid metabolism and targeted chiral methods that have been utilized for the analysis of the structurally diverse eicosanoids that arise. PMID:24957514

  6. High Throughput Quantitative Analysis of Serum Proteins using Glycopeptide Capture and Liquid Chromatography Mass Spectrometry

    SciTech Connect

    Zhang, Hui; Yi, Eugene C.; Li, Xiao-jun; Mallick, Parag; Kelly-Spratt, Karen S.; Masselon, Christophe D.; Camp, David G.; Smith, Richard D.; Kemp, Christopher; Aebersold, Ruedi

    2005-02-01

    It is expected that the composition of the serum proteome can provide valuable information about the state of the human body in health and disease, and that this information can be extracted via quantitative proteomic measurements. Suitable proteomic techniques need to be sensitive, reproducible and robust to detect potential biomarkers below the level of highly expressed proteins, to generate data sets that are comparable between experiments and laboratories, and have high throughput to support statistical studies. In this paper, we report a method for high throughput quantitative analysis of serum proteins. It consists of the selective isolation of peptides that are N-linked glycosylated in the intact protein, the analysis of these, no de-glycosylated peptides by LC-ESI-MS, and the comparative analysis of the resulting patterns. By focusing selectively on a few formerly N-linked glycopeptides per serum protein, the complexity of the analyte sample is significantly reduced and the sensitivity and throughput of serum proteome analysis are increased compared with the analysis of total tryptic peptides from unfractionated samples. We provide data that document the performance of the method and show that sera from untreated normal mice and genetically identical mice with carcinogen induced skin cancer can be unambiguously discriminated using unsupervised clustering of the resulting peptide patterns. We further identify, by tandem mass spectrometry, some of the peptides that were consistently elevated in cancer mice compared to their control littermates.

  7. Multivariate approach for the enantioselective analysis in micellar electrokinetic chromatography-mass spectrometry

    PubMed Central

    He, Jun; Shamsi, Shahab A.

    2009-01-01

    A mixture of two molecular micelles polysodium N-undecenoxy carbonyl-l-leucinate, (poly-l-SUCL) and polysodium N-undecanoyl leucylvalinate, (poly-l-SULV) was utilized in micellar electrokinetic chromatography-electrospray ionization-mass spectrometry (MEKC-ESI-MS) to simultaneously separate and detect enantiomers of binaphthyl derivatives. Separation parameters such as background buffer composition, voltage, temperature, and nebulizer pressure were optimized using a multivariate central composite design (CCD).Baseline enantioseparation for both analytes was achieved. The CCD was also used in the optimization of sheath liquid and spray chamber parameters to achieve optimum ESI-MS response. The results demonstrate that CCD is a powerful tool for the optimization of MEKC-MS parameters and the response surface model analysis can provide in-depth statistical understandings of the significant factors required to achieve maximum enantioresolution and ESI-MS sensitivity. PMID:19110258

  8. Analysis of Tropical Forest Fire Emissions Using in Situ Gas Chromatography/Mass Spectrometry during Sambba

    NASA Astrophysics Data System (ADS)

    Minaeian, J.; Lewis, A. C.; Edwards, P. M.; Evans, M. J.; Hopkins, J. R.; Lee, J. D.; Purvis, R.

    2014-12-01

    Vertical atmospheric profiles of volatile organic compounds (VOCs) were made over Amazonia using an in situ gas chromatography/mass spectrometer (GC/MS), including isoprene, methacrolein, methyl vinyl ketone and products of biomass burning such as benzene. Measurements were made in the Amazonian (Rondônia and Amazonas) region during September 2012, a period of extensive biomass burning. Data was obtained between 100m and 8500m from the FAAM BAe 146 research aircraft. Isoprene was observed to be constrained overwhelmingly to the boundary layer (height typically ~2500m) with mean boundary layer mixing ratio of ~2 ppbv and a peak of ~5 ppbv at the lowest flight levels of 100 m. First generation isoprene oxidation products, methyl vinyl ketone and methacrolein, were quantified individually rather than as the sum of the pair, which is more commonly found in the literature. Both MACR and MVK were constrained primarily to the boundary layer, however trace quantities could be seen in the free troposphere to a height of 8000 m. Benzene from biomass burning was observed in both boundary layer and free troposphere, with a peak mixing ratio of ~0.8 ppbv at 750 m. This work will present the spatial distribution of isoprene within the boundary as a function of underlying surface type. The vertical profiles of all species are then compared to representative simulations from the GEOS-Chem chemistry transport model and conclusions drawn on the success of the model in representing emissions and oxidation chemistry.

  9. Recent trends in application of multivariate curve resolution approaches for improving gas chromatography-mass spectrometry analysis of essential oils.

    PubMed

    Jalali-Heravi, Mehdi; Parastar, Hadi

    2011-08-15

    Essential oils (EOs) are valuable natural products that are popular nowadays in the world due to their effects on the health conditions of human beings and their role in preventing and curing diseases. In addition, EOs have a broad range of applications in foods, perfumes, cosmetics and human nutrition. Among different techniques for analysis of EOs, gas chromatography-mass spectrometry (GC-MS) is the most important one in recent years. However, there are some fundamental problems in GC-MS analysis including baseline drift, spectral background, noise, low S/N (signal to noise) ratio, changes in the peak shapes and co-elution. Multivariate curve resolution (MCR) approaches cope with ongoing challenges and are able to handle these problems. This review focuses on the application of MCR techniques for improving GC-MS analysis of EOs published between January 2000 and December 2010. In the first part, the importance of EOs in human life and their relevance in analytical chemistry is discussed. In the second part, an insight into some basics needed to understand prospects and limitations of the MCR techniques are given. In the third part, the significance of the combination of the MCR approaches with GC-MS analysis of EOs is highlighted. Furthermore, the commonly used algorithms for preprocessing, chemical rank determination, local rank analysis and multivariate resolution in the field of EOs analysis are reviewed. PMID:21726708

  10. Analytical platform for metabolome analysis of microbial cells using methyl chloroformate derivatization followed by gas chromatography-mass spectrometry.

    PubMed

    Smart, Kathleen F; Aggio, Raphael B M; Van Houtte, Jeremy R; Villas-Bôas, Silas G

    2010-09-01

    This protocol describes an analytical platform for the analysis of intra- and extracellular metabolites of microbial cells (yeast, filamentous fungi and bacteria) using gas chromatography-mass spectrometry (GC-MS). The protocol is subdivided into sampling, sample preparation, chemical derivatization of metabolites, GC-MS analysis and data processing and analysis. This protocol uses two robust quenching methods for microbial cultures, the first of which, cold glycerol-saline quenching, causes reduced leakage of intracellular metabolites, thus allowing a more reliable separation of intra- and extracellular metabolites with simultaneous stopping of cell metabolism. The second, fast filtration, is specifically designed for quenching filamentous micro-organisms. These sampling techniques are combined with an easy sample-preparation procedure and a fast chemical derivatization reaction using methyl chloroformate. This reaction takes place at room temperature, in aqueous medium, and is less prone to matrix effect compared with other derivatizations. This protocol takes an average of 10 d to complete and enables the simultaneous analysis of hundreds of metabolites from the central carbon metabolism (amino and nonamino organic acids, phosphorylated organic acids and fatty acid intermediates) using an in-house MS library and a data analysis pipeline consisting of two free software programs (Automated Mass Deconvolution and Identification System (AMDIS) and R). PMID:20885382

  11. Stable isotope labeling - Liquid chromatography/mass spectrometry for quantitative analysis of androgenic and progestagenic steroids.

    PubMed

    Guo, Ning; Liu, Ping; Ding, Jun; Zheng, Shu-Jian; Yuan, Bi-Feng; Feng, Yu-Qi

    2016-01-28

    Steroid hormones play important roles in mammal at very low concentrations and are associated with numerous endocrinology and oncology diseases. Therefore, quantitative analysis of steroid hormones can provide crucial information for uncovering underlying mechanisms of steroid hormones related diseases. In the current study, we developed a sensitive method for the detection of steroid hormones (progesterone, dehydroepiandrosterone, testosterone, pregnenolone, 17-hydroxyprogesterone, androstenedione and 17α-hydroxypregnenolone) in body fluids by stable isotope labeling coupled with liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) analysis. In this respect, a pair of isotopes labeling reagents, Girard reagent P (GP) and d5-Girard reagent P (d5-GP), were synthesized and utilized to label steroid hormones in follicular fluid samples and steroid hormone standards, respectively. The heavy labeled standards were used as internal standards for quantification to minimize quantitation deviation in MS analysis due to the matrix and ion suppression effects. The ionization efficiencies of steroid hormones were greatly improved by 4-504 folds through the introduction of a permanent charged moiety of quaternary ammonium from GP. Using the developed method, we successfully quantified steroid hormones in human follicular fluid. We found that the contents of testosterone and androstenedione exhibited significant increase while the content of pregnenolone had significant decrease in follicular fluid of polycystic ovarian syndrome (PCOS) patients compared with healthy controls, indicating that these steroid hormones with significant change may contribute to the pathogenesis of PCOS. Taken together, the developed stable isotope labeling coupled LC-ESI-MS/MS analysis demonstrated to be a promising method for the sensitive and accurate determination of steroid hormones, which may facilitate the in-depth investigation of steroid hormones related diseases. PMID:26755144

  12. Improvement of recovery and repeatability in liquid chromatography-mass spectrometry analysis of peptides.

    PubMed

    van Midwoud, Paul M; Rieux, Laurent; Bischoff, Rainer; Verpoorte, Elisabeth; Niederländer, Harm A G

    2007-02-01

    Poor repeatability of peak areas is a problem frequently encountered in peptide analysis with nanoLiquid Chromatography coupled on-line with Mass Spectrometry (nanoLC-MS). As a result, quantitative analysis will be seriously hampered unless the observed variability can be corrected in some way. Currently, labeling techniques or addition of internal standards are often applied for this purpose. However, these procedures are elaborate and error-prone and may render complex samples even more complex. Moreover, whenever poor repeatability results from variable recovery, not just quantification, but also sensitivity is affected. We have studied the parameters influencing the repeatability of chromatographic peak areas for a model set of proteolytic peptides (i.e., a cytochrome c tryptic digest) in nanoLC-MS analysis. It is demonstrated that repeatability issues are mainly due to poor recovery of peptides from the sample vial. Problems are largely resolved by addition of an organic modifier to the sample vial to improve solubility of the peptides, but care needs to be taken not to lose peptides due to reduced affinity for reversed-phase materials. Good results are obtained when applying dimethylsulfoxide (DMSO) for this purpose. When applying DMSO, repeatability increases, and the limit of detection (LOD) decreases. For the most hydrophobic peptides, a gain in LOD of at least an order of magnitude is obtained. In an aqueous sample containing 0.1% formic acid (FA), it is possible to detect 100-200 fmol of peptide, whereas +/-10 fmol can be detected in a sample containing 5% FA and 25% DMSO (10 microL injections). PMID:17269734

  13. Systematic Optimization of Long Gradient Chromatography Mass Spectrometry for Deep Analysis of Brain Proteome

    SciTech Connect

    Wang, Hong; Yang, Yanling; Li, Yuxin; Bai, Bing; Wang, Xusheng; Tan, Haiyan; Liu, Tao; Beach, Thomas G.; Peng, Junmun; Wu, Zhiping

    2015-02-06

    Development of high resolution liquid chromatography (LC) is essential for improving the sensitivity and throughput of mass spectrometry (MS)-based proteomics. Here we present systematic optimization of a long gradient LC-MS/MS platform to enhance protein identification from a complex mixture. The platform employed an in-house fabricated, reverse phase column (100 μm x 150 cm) coupled with Q Exactive MS. The column was capable of achieving a peak capacity of approximately 700 in a 720 min gradient of 10-45% acetonitrile. The optimal loading level was about 6 micrograms of peptides, although the column allowed loading as many as 20 micrograms. Gas phase fractionation of peptide ions further increased the number of peptide identification by ~10%. Moreover, the combination of basic pH LC pre-fractionation with the long gradient LC-MS/MS platform enabled the identification of 96,127 peptides and 10,544 proteins at 1% protein false discovery rate in a postmortem brain sample of Alzheimer’s disease. As deep RNA sequencing of the same specimen suggested that ~16,000 genes were expressed, current analysis covered more than 60% of the expressed proteome. Further improvement strategies of the LC/LC-MS/MS platform were also discussed.

  14. Systematic Optimization of Long Gradient Chromatography Mass Spectrometry for Deep Analysis of Brain Proteome

    PubMed Central

    2015-01-01

    The development of high-resolution liquid chromatography (LC) is essential for improving the sensitivity and throughput of mass spectrometry (MS)-based proteomics. Here we present systematic optimization of a long gradient LC–MS/MS platform to enhance protein identification from a complex mixture. The platform employed an in-house fabricated, reverse-phase long column (100 μm × 150 cm, 5 μm C18 beads) coupled to Q Exactive MS. The column was capable of achieving a peak capacity of ∼700 in a 720 min gradient of 10–45% acetonitrile. The optimal loading level was ∼6 μg of peptides, although the column allowed loading as many as 20 μg. Gas-phase fractionation of peptide ions further increased the number of peptide identification by ∼10%. Moreover, the combination of basic pH LC prefractionation with the long gradient LC–MS/MS platform enabled the identification of 96 127 peptides and 10 544 proteins at 1% protein false discovery rate in a post-mortem brain sample of Alzheimer’s disease. Because deep RNA sequencing of the same specimen suggested that ∼16 000 genes were expressed, the current analysis covered more than 60% of the expressed proteome. Further improvement strategies of the LC/LC–MS/MS platform were also discussed. PMID:25455107

  15. Evaluation of beer deterioration by gas chromatography-mass spectrometry/multivariate analysis: a rapid tool for assessing beer composition.

    PubMed

    Rodrigues, João A; Barros, António S; Carvalho, Beatriz; Brandão, Tiago; Gil, Ana M; Ferreira, António C Silva

    2011-02-18

    Beer stability is a major concern for the brewing industry, as beer characteristics may be subject to significant changes during storage. This paper describes a novel non-targeted methodology for monitoring the chemical changes occurring in a lager beer exposed to accelerated aging (induced by thermal treatment: 18 days at 45 °C), using gas chromatography-mass spectrometry in tandem with multivariate analysis (GC-MS/MVA). Optimization of the chromatographic run was performed, achieving a threefold reduction of the chromatographic time. Although losing optimum resolution, rapid GC runs showed similar chromatographic profiles and semi-quantitative ability to characterize volatile compounds. To evaluate the variations on the global volatile signature (chromatographic profile and m/z pattern of fragmentation in each scan) of beer during thermal deterioration, a non-supervised multivariate analysis method, Principal Component Analysis (PCA), was applied to the GC-MS data. This methodology allowed not only the rapid identification of the degree of deterioration affecting beer, but also the identification of specific compounds of relevance to the thermal deterioration process of beer, both well established markers such as 5-hydroxymethylfufural (5-HMF), furfural and diethyl succinate, as well as other compounds, to our knowledge, newly correlated to beer aging. PMID:21227435

  16. Liquid chromatography-mass spectrometry analysis of five bisphosphonates in equine urine and plasma.

    PubMed

    Wong, April S Y; Ho, Emmie N M; Wan, Terence S M; Lam, Kenneth K H; Stewart, Brian D

    2015-08-15

    Bisphosphonates are used in the management of skeletal disorder in humans and horses, with tiludronic acid being the first licensed veterinary medicine in the treatment of lameness associated with degenerative joint disease. Bisphosphonates are prohibited in horseracing according to Article 6 of the International Agreement on Breeding, Racing and Wagering (published by the International Federation of Horseracing Authorities). In order to control the use of bisphosphonates in equine sports, an effective method to detect the use of bisphosphonates is required. Bisphosphonates are difficult-to-detect drugs due to their hydrophilic properties. The complexity of equine matrices also added to their extraction difficulties. This study describes a method for the simultaneous detection of five bisphosphonates, namely alendronic acid, clodronic acid, ibandronic acid, risedronic acid and tiludronic acid, in equine urine and plasma. Bisphosphonates were first isolated from the sample matrices by solid-phase extractions, followed by methylation with trimethylsilyldiazomethane prior to liquid chromatography - tandem mass spectrometry analysis using selective reaction monitoring in the positive electrospray ionization mode. The five bisphosphonates could be detected at low ppb levels in 0.5mL equine plasma or urine with acceptable precision, fast instrumental turnaround time, and negligible matrix interferences. The method has also been applied to the excretion study of tiludronic acid in plasma and urine collected from a horse having been administered a single dose of tiludronic acid. The applicability and effectiveness of the method was demonstrated by the successful detection and confirmation of the presence of tiludronic acid in an overseas equine urine sample. To our knowledge, this is the first reported method in the successful screening and confirmation of five amino- and non-amino bisphosphonates in equine biological samples. PMID:26143477

  17. 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

  18. Fuzzy C-means clustering for chromatographic fingerprints analysis: A gas chromatography-mass spectrometry case study.

    PubMed

    Parastar, Hadi; Bazrafshan, Alisina

    2016-03-18

    Fuzzy C-means clustering (FCM) is proposed as a promising method for the clustering of chromatographic fingerprints of complex samples, such as essential oils. As an example, secondary metabolites of 14 citrus leaves samples are extracted and analyzed by gas chromatography-mass spectrometry (GC-MS). The obtained chromatographic fingerprints are divided to desired number of chromatographic regions. Owing to the fact that chromatographic problems, such as elution time shift and peak overlap can significantly affect the clustering results, therefore, each chromatographic region is analyzed using multivariate curve resolution-alternating least squares (MCR-ALS) to address these problems. Then, the resolved elution profiles are used to make a new data matrix based on peak areas of pure components to cluster by FCM. The FCM clustering parameters (i.e., fuzziness coefficient and number of cluster) are optimized by two different methods of partial least squares (PLS) as a conventional method and minimization of FCM objective function as our new idea. The results showed that minimization of FCM objective function is an easier and better way to optimize FCM clustering parameters. Then, the optimized FCM clustering algorithm is used to cluster samples and variables to figure out the similarities and dissimilarities among samples and to find discriminant secondary metabolites in each cluster (chemotype). Finally, the FCM clustering results are compared with those of principal component analysis (PCA), hierarchical cluster analysis (HCA) and Kohonon maps. The results confirmed the outperformance of FCM over the frequently used clustering algorithms. PMID:26916594

  19. Quantitative analysis of urinary glycerol levels for doping control purposes using gas chromatography-mass spectrometry.

    PubMed

    Thevis, Mario; Guddat, Sven; Flenker, Ulrich; Schänzer, Wilhelm

    2008-01-01

    The administration of glycerol to endurance athletes results in an increased fluid retention and improved performance, particularly under hot and humid conditions. Consequently, glycerol is considered relevant for sports drug testing and methods for its detection in urine specimens are required. A major issue in this regard is the natural occurrence of trace amounts of glycerol in human urine, which necessitates a quantitative analysis and the determination of normal urinary glycerol levels under various sporting conditions. A quantitative method was established using a gas chromatography/isotope-dilution mass spectrometry-based approach that was validated with regard to lower limit of detection (0.3 microg mL(-1)), lower limit of quantification (0.9 microg mL(-1)), specificity, linearity (1.0-98.0 microg mL(-1)), intraday and interday precision (<20% at 2.4, 24.1 and 48.2 microg mL(-1)) as well as accuracy (92-110%). Sample aliquots of 20 microL were enriched with five-fold deuterated glycerol, dried and derivatised using N-methyl-trimethylsilyltrifluoroacetamide (MSTFA) before analysis. The established method was applied to a total of 1039 doping control samples covering various sport disciplines (349 endurance samples, 286 strength sport samples, 325 game sport samples and 79 other samples) in- and out-of-competition, which provided quantitative information about the glycerol content commonly observed in elite athletes' urine samples. About 85% of all specimens yielded glycerol concentrations < 20.0 microg mL(-1) and few reached values up to 132.6 microg mL(-1). One further sample, however, was found to contain 2690 microg mL(-1), which might indicate the misuse of glycerol, but no threshold for urinary glycerol concentrations has been established yet due to the lack of substantial data. Based on the results obtained from the studied reference population, a threshold for glycerol levels in urine set at 200 microg mL(-1) is suggested, which provides a tool to doping control laboratories to test for the misuse of this agent in elite and amateur sport. PMID:18708691

  20. Analysis of chemical profiles of insect adhesion secretions by gas chromatography-mass spectrometry.

    PubMed

    Reitz, Manuela; Gerhardt, Heike; Schmitt, Christian; Betz, Oliver; Albert, Klaus; Lämmerhofer, Michael

    2015-01-01

    This article reports on the chemical analysis of molecular profiles of tarsal secretions of the desert locust Schistocerca gregaria (Forsskål, 1775) by gas chromatography hyphenated with quadrupol mass spectrometry (GC-MS) as well as (1)H-nuclear magnetic resonance ((1)H NMR) spectroscopy. Special focus of this study was to elaborate on sampling methods which enable selective microscale extraction of insect secretions in a spatially controlled manner, in particular tarsal adhesive secretions and secretions located on cuticle surfaces at the tibia. Various solvent sampling procedures and contact solid-phase microextraction (SPME) methods were compared in terms of comprehensiveness and extraction efficiencies as measured by signal intensities in GC-MS. Solvent sampling with water as extraction solvent gave access to the elucidation of chemical profiles of polar compound classes such as amino acids and carbohydrates, but is extremely tedious. Contact SPME on the other hand can be regarded as a simplified and more elegant alternative, in particular for the lipophilic compound fraction. Many proteinogenic amino acids and ornithine as well as carbohydrate monomers arabinose, xylose, glucose, and galactose were detected in tarsal secretions after acid hydrolysis of aqueous extracts. Qualitatively similar but quantitatively significantly different molecular profiles were found for the lipid fraction which contained mainly n-alkanes and internally branched monomethyl-, dimethyl-, and trimethyl-alkanes in the C23-C49 range as well as long chain fatty acids and aldehydes. Especially, hydrocarbons with >C40 carbon numbers have previously been rarely reported for insect secretions. The results suggest that the investigated insect secretions are complex emulsions which allow the attachment of tarsi on various otherwise incompatible materials of smooth and rough surfaces. The solid consistence of the established alkanes at ambient temperatures might contribute to a semi-solid consistence of the adhesive, amalgamating partly opposing functions such as slip resistance, tarsal release, desiccation resistance, and mechanical compliance. The methods developed can be extended to other similar applications of studying compositions of insect secretions of other species. PMID:25479867

  1. Gas Chromatography-Mass Spectrometry Analysis of Ulva fasciata (Green Seaweed) Extract and Evaluation of Its Cytoprotective and Antigenotoxic Effects.

    PubMed

    Rodeiro, Idania; Olguín, Sitlali; Santes, Rebeca; Herrera, José A; Pérez, Carlos L; Mangas, Raisa; Hernández, Yasnay; Fernández, Gisselle; Hernández, Ivones; Hernández-Ojeda, Sandra; Camacho-Carranza, Rafael; Valencia-Olvera, Ana; Espinosa-Aguirre, Jesús Javier

    2015-01-01

    The chemical composition and biological properties of Ulva fasciata aqueous-ethanolic extract were examined. Five components were identified in one fraction prepared from the extract by gas chromatography-mass spectrometry, and palmitic acid and its ethyl ester accounted for 76% of the total identified components. Furthermore, we assessed the extract's antioxidant properties by using the DPPH, ABTS, and lipid peroxidation assays and found that the extract had a moderate scavenging effect. In an experiment involving preexposition and coexposition of the extract (1-500 µg/mL) and benzo[a]pyrene (BP), the extract was found to be nontoxic to C9 cells in culture and to inhibit the cytotoxicity induced by BP. As BP is biotransformed by CYP1A and CYP2B subfamilies, we explored the possible interaction of the extract with these enzymes. The extract (25-50 µg/mL) inhibited CYP1A1 activity in rat liver microsomes. Analysis of the inhibition kinetics revealed a mixed-type inhibitory effect on CYP1A1 supersome. The effects of the extract on BP-induced DNA damage and hepatic CYP activity in mice were also investigated. Micronuclei induction by BP and liver CYP1A1/2 activities significantly decreased in animals treated with the extract. The results suggest that Ulva fasciata aqueous-ethanolic extract inhibits BP bioactivation and it may be a potential chemopreventive agent. PMID:26612994

  2. Alternative method for gas chromatography-mass spectrometry analysis of short-chain fatty acids in faecal samples.

    PubMed

    García-Villalba, Rocio; Giménez-Bastida, Juan A; García-Conesa, Maria T; Tomás-Barberán, Francisco A; Espín, Juan Carlos; Larrosa, Mar

    2012-06-01

    Short-chain fatty acids are the major end products of bacterial metabolism in the large bowel. They derive mostly from the bacterial breakdown of carbohydrates and are known to have positive health benefits. Due to the biological relevance of these compounds it is important to develop efficient, cheap, fast, and sensitive analytical methods that enable the identification and quantification of the short-chain fatty acids in a large number of biological samples. In this study, a gas chromatography-mass spectrometry method was developed and validated for the analysis of short-chain fatty acids in faecal samples. These volatile compounds were extracted with ethyl acetate and 4-methyl valeric acid was used as an internal standard. No further cleanup, concentration, and derivatization steps were needed and the extract was directly injected onto the column. Recoveries ranged between 65 and 105%, and no matrix effects were observed. The proposed method has wide linear ranges, good inter- and intraday variability values (below 2.6 and 5.6%, respectively) and limits of detection between 0.49 μM (0.29 μg/g) and 4.31 μM (3.8 μg/g). The applicability of this analytical method was successfully tested in faecal samples from rats and humans. PMID:22674825

  3. Alternative method for gas chromatography-mass spectrometry analysis of short-chain fatty acids in faecal samples.

    PubMed

    García-Villalba, Rocio; Giménez-Bastida, Juan A; García-Conesa, Maria T; Tomás-Barberán, Francisco A; Carlos Espín, Juan; Larrosa, Mar

    2012-08-01

    Short-chain fatty acids are the major end products of bacterial metabolism in the large bowel. They derive mostly from the bacterial breakdown of carbohydrates and are known to have positive health benefits. Due to the biological relevance of these compounds it is important to develop efficient, cheap, fast, and sensitive analytical methods that enable the identification and quantification of the short-chain fatty acids in a large number of biological samples. In this study, a gas chromatography-mass spectrometry method was developed and validated for the analysis of short-chain fatty acids in faecal samples. These volatile compounds were extracted with ethyl acetate and 4-methyl valeric acid was used as an internal standard. No further cleanup, concentration, and derivatization steps were needed and the extract was directly injected onto the column. Recoveries ranged between 65 and 105%, and no matrix effects were observed. The proposed method has wide linear ranges, good inter- and intraday variability values (below 2.6 and 5.6%, respectively) and limits of detection between 0.49 μM (0.29 μg/g) and 4.31 μM (3.8 μg/g). The applicability of this analytical method was successfully tested in faecal samples from rats and humans. PMID:22865755

  4. Gas Chromatography-Mass Spectrometry Analysis of Ulva fasciata (Green Seaweed) Extract and Evaluation of Its Cytoprotective and Antigenotoxic Effects

    PubMed Central

    Rodeiro, Idania; Olguín, Sitlali; Santes, Rebeca; Herrera, José A.; Pérez, Carlos L.; Mangas, Raisa; Hernández, Yasnay; Fernández, Gisselle; Hernández, Ivones; Hernández-Ojeda, Sandra; Camacho-Carranza, Rafael; Valencia-Olvera, Ana; Espinosa-Aguirre, Jesús Javier

    2015-01-01

    The chemical composition and biological properties of Ulva fasciata aqueous-ethanolic extract were examined. Five components were identified in one fraction prepared from the extract by gas chromatography-mass spectrometry, and palmitic acid and its ethyl ester accounted for 76% of the total identified components. Furthermore, we assessed the extract's antioxidant properties by using the DPPH, ABTS, and lipid peroxidation assays and found that the extract had a moderate scavenging effect. In an experiment involving preexposition and coexposition of the extract (1–500 µg/mL) and benzo[a]pyrene (BP), the extract was found to be nontoxic to C9 cells in culture and to inhibit the cytotoxicity induced by BP. As BP is biotransformed by CYP1A and CYP2B subfamilies, we explored the possible interaction of the extract with these enzymes. The extract (25–50 µg/mL) inhibited CYP1A1 activity in rat liver microsomes. Analysis of the inhibition kinetics revealed a mixed-type inhibitory effect on CYP1A1 supersome. The effects of the extract on BP-induced DNA damage and hepatic CYP activity in mice were also investigated. Micronuclei induction by BP and liver CYP1A1/2 activities significantly decreased in animals treated with the extract. The results suggest that Ulva fasciata aqueous-ethanolic extract inhibits BP bioactivation and it may be a potential chemopreventive agent. PMID:26612994

  5. Acute toxicity of plant essential oils to scarab larvae (Coleoptera: Scarabaeidae) and their analysis by gas chromatography-mass spectrometry.

    PubMed

    Ranger, Christopher M; Reding, Michael E; Oliver, Jason B; Moyseenko, James J; Youssef, Nadeer; Krause, Charles R

    2013-02-01

    Larvae of scarab beetles (Coleoptera: Scarabaeidae) are important contaminant and root-herbivore pests of ornamental crops. To develop alternatives to conventional insecticides, 24 plant-based essential oils were tested for their acute toxicity against third instars of the Japanese beetle Popillia japonica Newman, European chafer Rhizotrogus majalis (Razoumowsky), oriental beetle Anomala orientalis (Waterhouse), and northern masked chafer Cyclocephala borealis Arrow. Diluted solutions were topically applied to the thorax, which allowed for calculating LD50 and LD90 values associated with 1 d after treatment. A wide range in acute toxicity was observed across all four scarab species. Of the 24 oils tested, allyl isothiocyanate, cinnamon leaf, clove, garlic, and red thyme oils exhibited toxicity to all four species. Allyl isothiocyanate was the most toxic oil tested against the European chafer, and among the most toxic against the Japanese beetle, oriental beetle, and northern masked chafer. Red thyme was also comparatively toxic to the Japanese beetle, oriental beetle, European chafer, and northern masked chafer. Interspecific variability in susceptibility to the essential oils was documented, with 12, 11, 8, and 6 of the 24 essential oils being toxic to the oriental beetle, Japanese beetle, European chafer, and northern masked chafer, respectively. Analysis of the active oils by gas chromatography-mass spectrometry revealed a diverse array of compounds, mostly consisting of mono- and sesquiterpenes. These results will aid in identifying active oils and their constituents for optimizing the development of plant essential oil mixtures for use against scarab larvae. PMID:23448028

  6. Development of Sensitive and Specific Analysis of Vildagliptin in Pharmaceutical Formulation by Gas Chromatography-Mass Spectrometry

    PubMed Central

    Uçaktürk, Ebru

    2015-01-01

    A sensitive and selective gas chromatography-mass spectrometry (GC-MS) method was developed and fully validated for the determination of vildagliptin (VIL) in pharmaceutical formulation. Prior to GC-MS analysis, VIL was efficiently derivatized with MSTFA/NH4I/β-mercaptoethanol at 60°C for 30 min. The obtained O-TMS derivative of VIL was detected by selected ion monitoring mode using the diagnostic ions m/z 223 and 252. Nandrolone was chosen as internal standard. The GC-MS method was fully validated by the following validation parameters: limit of detection (LOD) and quantitation (LOQ), linearity, precision, accuracy, specificity, stability, robustness, and ruggedness. LOD and LOQ were found to be 1.5 and 3.5 ng mL−1, respectively. The GC-MS method is linear in the range of 3.5–300 ng mL−1. The intra- and interday precision values were less than ≤3.62%. The intra- and interday accuracy values were found in the range of −0.26–2.06%. Finally, the GC-MS method was successfully applied to determine VIL in pharmaceutical formulation. PMID:26682085

  7. Fast analysis of isobaric grape anthocyanins by Chip-liquid chromatography/mass spectrometry.

    PubMed

    Flamini, Riccardo; De Rosso, Mirko; Smaniotto, Anna; Panighel, Annarita; Vedova, Antonio Dalla; Seraglia, Roberta; Traldi, Pietro

    2009-09-01

    In a previous work, direct-infusion electrospray ionization ion trap tandem mass spectrometry (ESI-IT-MS/MS) was applied to the study of anthocyanins in extracts from the skins of Clinton grapes, a non-Vitis vinifera red grape variety qualitatively and quantitatively rich in anthocyanins. A good characterization of anthocyaninins was obtained, but it was impossible to differentiate some compounds with the same nominal mass but with different elemental composition. In this work, the capabilities of quadrupole time-of-flight mass spectrometry (QTOF-MS) coupled with Chip-liquid chromatography (LC-Chip) were applied to the study of Clinton anthocyanins and this method provided the complete sample anthocyanin fingerprint in less than 5 min. Multi-stage mass spectrometry (MS(n); n >2) was not necessary to identify isobaric compounds, nor were deuterium-exchange experiments necessary to distinguish between compounds containing the same aglycone. The fast separation bypasses the problem of petunidin-3-O-(6-O-acetyl)monoglucoside and delphinidin-3,5-O-diglucoside quantification, present in the direct-infusion ESI-ITMS approach, due to overlapping with matrix interferences. PMID:19670341

  8. 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 (μg/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 μg/kg dry weight.

  9. Sediment matrix effects in analysis of pyrethroid insecticides using gas chromatography-mass spectrometry.

    PubMed

    Wang, Dongli; You, Jing; Lydy, Michael J

    2010-10-01

    In the present study, we developed a gas chromatography-quadrupole mass spectrometry method for analyzing nine pyrethroid insecticides in sediment after accelerated solvent extraction and solid phase extraction cleanup. The operation was optimized, and negative chemical ionization was selected to improve analytical selectivity. The sediment matrix effects on qualification were evaluated, and matrix-matched standard solutions, along with the internal standard calibration, were used to reduce the matrix-induced chromatographic response enhancement. The method detection limits were 0.68 to 1.43 microg/kg dry weight (dw), and recoveries were 70.3 to 143.3%, 61.1 to 169.7%, and 65.7 to 118.8%, with relative SDs of 4.2% to 32.1%, 4.9 to 23.6%, and 1.5 to 23.3% at the spiked levels of 1.0, 5.0 and 20 microg/kg dw, respectively. The method was also validated by measuring pyrethroids in field-contaminated sediment samples collected in central California and southern Illinois. PMID:20340013

  10. ANALYSIS OF HAZARDOUS WASTE AND ENVIRONMENTAL EXTRACTS BY CAPILLARY GAS CHROMATOGRAPHY/FOURIER TRANSFORM INFRARED SPECTROMETRY AND CAPILLARY GAS CHROMATOGRAPHY/MASS SPECTROMETRY

    EPA Science Inventory

    The relative sensitivities of fused-silica capillary column gas chromatography/Fourier transform infrared spectrometry (FSCC/GC/FT-IR) versus packed-column GC/FT-IR and FSCC/GC/FT-IR versus fused-silica capillary column gas chromatography/mass spectrometry (FSCC/GC/MS) were compa...

  11. 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

  12. 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.

  13. PRECOLUMN SAMPLE ENRICHMENT DEVICE FOR ANALYSIS OF AMBIENT VOLATILE ORGANICS BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY

    EPA Science Inventory

    Gas chromatographic-mass spectrometric (GC/MS) identification of air pollutants generally requires a preconcentration step to provide sufficient sample for analysis. Cryogenic trapping is often used to enrich the sample since nitrogen and oxygen are not condensed. It does, howeve...

  14. Direct analysis of fatty acid profile from milk by thermochemolysis-gas chromatography-mass spectrometry.

    PubMed

    Gomes Reis, Mariza; dos Reis, Marlon Martins; Leath, Shane; Stelwagen, Kerst

    2011-01-14

    The fatty acid composition of milk is of considerable interest due to their nutritional and functional properties. Although rapid milk fat separation and transesterification procedures have been developed, the overall procedure remains time consuming, specially, for the analysis of a large number of samples. In this work, a fast and simple method for direct profiling of fatty acids from milk using thermochemolysis has been developed. This method has the capability of directly analyse fatty acids from one drop of milk without fat extraction or cleanup. Our approach for thermochemolysis is based on thermal desorption integrated with a cold trap inlet. The optimized method does not present isomerisation/degradation of polyunsaturated fatty acid and shows milk fatty acid profiles comparable to the conventional method based on fat extraction and alkaline transesterification. Overall, this method has demonstrated significant potential for high throughput analysis of fatty acids in milk. PMID:21144530

  15. Recent advances and trends in the liquid-chromatography-mass spectrometry analysis of flavonoids.

    PubMed

    de Villiers, André; Venter, Pieter; Pasch, Harald

    2016-01-22

    Flavonoids have elicited significant attention as a result of their importance in plants, their influence on the properties of natural-product derived commodities and especially as a consequence of their purported health benefits. Research in all of these fields relies heavily on accurate analytical data, and in this LC-MS has come to play an influential role by allowing relatively fast tentative identification and accurate quantification of low levels of flavonoids in a variety of matrices. The field has undergone rapid expansion in the last decade due to important developments in both HPLC and MS instrumentation, which nowadays allow much faster and more accurate analysis of flavonoids. This contribution aims to provide an overview of these developments and their application in flavonoid analysis since 2009. The discussion is focussed first on methodologies which provide improved LC separation of flavonoids in terms of speed and/or resolution, including ultra high pressure LC (UHPLC), monolithic and superficially porous phases, high temperature LC (HTLC) and comprehensive two-dimensional LC (LC×LC). The fundamental background relevant to each of these will be briefly outlined, as well as the implications and promise of their hyphenation to MS. Secondly, the possibilities and limitations of a range of the latest MS instruments available in combination with advanced LC analysis will be discussed, including ion trap, triple quadrupole, time-of-flight, Orbitrap, ion mobility and various hybrid instruments. Examples from the latest literature will be used to illustrate the performance gains achievable in flavonoid analysis by the hyphenation of advanced LC separation and high-end MS instrumentation. PMID:26718188

  16. Analysis of volatile compounds responsible for kiwifruit aroma by desiccated headspace gas chromatography-mass spectrometry.

    PubMed

    Zhang, Chun-Yun; Zhang, Qiong; Zhong, Cai-Hong; Guo, Ming-Quan

    2016-04-01

    A new method for desiccated headspace (DHS) sampling of aqueous sample to GC-MS for the analysis of volatile compounds responsible for kiwifruit aroma in different kiwifruit cultivars has been developed based on the complete hydrate formation between the sample solvent (water) with anhydrous salt (calcium chloride) at an elevated temperature (above the boiling point of the aqueous sample) in a non-contact format, which overcame the water-effect challenge to directly introduce aqueous sample into GC-MS analysis. By means of DHS, the volatile compounds in three different kiwifruit cultivars were analyzed and compared under the optimized operating conditions, mainly time and temperature for headspace equilibration, column temperature program for GC-MS measurement. As a result, 20 peaks of volatile compounds responsible for kiwifruit aroma were detected and remarkable differences were found in the relative contents of three major volatile compounds among the three different kiwifruit cultivars, i.e., acetaldehyde, ethanol and furfural. The DHS sampling technique used in the present method can make the GC-MS analysis of volatile compounds in the aqueous sample within complex matrix possible without contaminating the GC-MS instrument. In terms of the analysis of volatile compounds in kiwifruit, the present method enabled a direct measurement on the filtrate of the aqueous kiwifruit pulp, without intermediate trap phase for the extraction of analytes, which will be more reliable and simpler as compared with any other headspace method in use. Thus, DHS coupled with GC-MS will be a new valuable tool available for the kiwifruit related research and organoleptic quality control. PMID:26922094

  17. Carbon isotopic analysis of atmospheric methane by isotope-ratio-monitoring gas chromatography-mass spectrometry

    NASA Technical Reports Server (NTRS)

    Merritt, Dawn A.; Hayes, J. M.; Des Marais, David J.

    1995-01-01

    Less than 15 min are required for the determination of delta C(sub PDB)-13 with a precision of 0.2 ppt(1 sigma, single measurement) in 5-mL samples of air containing CH4 at natural levels (1.7 ppm). An analytical system including a sample-introduction unit incorporating a preparative gas chromatograph (GC) column for separation of CH4 from N2, O2, and Ar is described. The 15-min procedure includes time for operation of that system, high-resolution chromatographic separation of the CH4, on-line combustion and purification of the products, and isotopic calibration. Analyses of standards demonstrate that systematic errors are absent and that there is no dependence of observed values of delta on sample size. For samples containing 100 ppm or more CH4, preconcentration is not required and the analysis time is less than 5 min. The system utilizes a commercially available, high-sensitivity isotope-ratio mass spectrometer. For optimal conditions of smaple handling and combustion, performance of the system is within a factor of 2 of the shot-noise limit. The potential exists therefore for analysis of samples as small as 15 pmol CH4 with a standard deviation of less than 1 ppt.

  18. 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.

  19. [Hair analysis of abused drugs with gas-chromatography mass spectrometry].

    PubMed

    Klausz, Gabriella; Keller, Eva; Róna, Kálmán

    2009-01-01

    Beside the traditionally used body-fluids, defining the abuse-material by the use of hair samples is more and more widespread in the forensic toxicological practice. Using the hair allows the rectrospective examination of the abuse-material, and due to the sensitive measuring technics, even one-time use can be proven. A further possibility is the segment-analysis which allows investigation of the abuse-history retroactive for months depending on the length of the hair. The quantitative parameters of the abuse can not always be estimated precisely since the details of the build-up in the hair are complicated and are not clear even today. Furthermore, the sampling, sample preparation and the measuring method will all influence the results. Our paper reviews the opiates, cocain, amfetamin derivatives, cannabinoids, alcohol-consumption markers and the frequently found drugs in the forensic toxicology as determined by using hair samples. PMID:19634634

  20. iMatch: A retention index tool for analysis of gas chromatography-mass spectrometry data

    PubMed Central

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

    2011-01-01

    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 results show that 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 (Inorm) with the ramp condition is similar to the linear retention index (IT), while the Inorm with the isothermal condition is similar to the Kovts retention index (I). As for the Inorm with the complex condition, these data should be treated as an additional group, because the mean Inorm value of the polar column is significantly different from the IT. 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

  1. Response to weaning and dietary L-glutamine supplementation: metabolomic analysis in piglets by gas chromatography/mass spectrometry*

    PubMed Central

    Xiao, Ying-ping; Wu, Tian-xing; Hong, Qi-hua; Sun, Jiang-ming; Chen, An-guo; Yang, Cai-mei; Li, Xiao-yan

    2012-01-01

    A novel metabolomic method based on gas chromatography/mass spectrometry (GC-MS) was applied to determine the metabolites in the serum of piglets in response to weaning and dietary L-glutamine (Gln) supplementation. Thirty-six 21-d-old piglets were randomly assigned into three groups. One group continued to suckle from the sows (suckling group), whereas the other two groups were weaned and their diets were supplemented with 1% (w/w) Gln or isonitrogenous L-alanine, respectively, representing Gln group or control group. Serum samples were collected to characterize metabolites after a 7-d treatment. Results showed that twenty metabolites were down-regulated significantly (P<0.05) in control piglets compared with suckling ones. These data demonstrated that early weaning causes a wide range of metabolic changes across arginine and proline metabolism, aminosugar and nucleotide metabolism, galactose metabolism, glycerophospholipid metabolism, biosynthesis of unsaturated fatty acid, and fatty acid metabolism. Dietary Gln supplementation increased the levels of creatinine,D-xylose, 2-hydroxybutyric acid, palmitelaidic acid, and α-L-galactofuranose (P<0.05) in early weaned piglets, and were involved in the arginine and proline metabolism, carbohydrate metabolism, and fatty acid metabolism. A leave-one-out cross-validation of random forest analysis indicated that creatinine was the most important metabolite among the three groups. Notably, the concentration of creatinine in control piglets was decreased (P=0.00001) compared to the suckling piglets, and increased (P=0.0003) in Gln-supplemented piglets. A correlation network for weaned and suckling piglets revealed that early weaning changed the metabolic pathways, leading to the abnormality of carbohydrate metabolism, amino acid metabolism, and lipid metabolism, which could be partially improved by dietary Gln supplementation. These findings provide fresh insight into the complex metabolic changes in response to early weaning and dietary Gln supplementation in piglets. PMID:22761248

  2. Accurate analysis of trace earthy-musty odorants in water by headspace solid phase microextraction gas chromatography-mass spectrometry.

    PubMed

    Ma, Kang; Zhang, Jin Na; Zhao, Min; He, Ya Juan

    2012-06-01

    A simple and sensitive method was developed for the simultaneous separation and determination of trace earthy-musty compounds including geosmin, 2-methylisoborneol, 2-isobutyl-3-methoxypyrazine, 2-isopropyl-3-methoxypyrazine, 2,3,4-trichloroanisole, 2,4,6-trichloroanisole, and 2,3,6-trichloroanisole in water samples. This method combined headspace solid-phase microextraction (HS-SPME) with gas chromatography-mass spectrometry and used naphthalene-d(8) as internal standard. A divinylbenzene/carboxen/polydimethylsiloxane fiber exposing at 90°C for 30 min provided effective sample enrichment in HS-SPME. These compounds were separated by a DB-1701MS capillary column and detected in selected ion monitoring mode within 12 min. The method showed a good linearity from 1 to 100 ng L(-1) and detection limits within (0.25-0.61 ng L(-1)) for all compounds. Using naphthalene-d(8) as the internal standard, the intra-day relative standard deviation (RSD) was within (2.6-3.4%), while the inter-day RSD was (3.5-4.9%). Good recoveries were obtained for tap water (80.5-90.6%), river water (81.5-92.4%), and lake water (83.5-95.2%) spiked at 10 ng L(-1). Compared with other methods using HS-SPME for determination of odor compounds in water samples, this present method had more analytes, better precision, and recovery. This method was successfully applied for analysis of earthy-musty odors in water samples from different sources. PMID:22740259

  3. Molecular analysis of intact preen waxes of Calidris canutus (Aves: Scolopacidae) by gas chromatography/mass spectrometry.

    PubMed

    Dekker, M H; Piersma, T; Damsté, J S

    2000-05-01

    The intact preen wax esters of the red knot Calidris canutus were studied with gas chromatography/mass spectrometry (GC/MS) and GC/MS/MS. In this latter technique, transitions from the molecular ion to fragment ions representing the fatty acid moiety of the wax esters were measured, providing additional resolution to the analysis of wax esters. The C21-C32 wax esters are composed of complex mixtures of hundreds of individual isomers. The odd carbon-numbered wax esters are predominantly composed of even carbon-numbered n-alcohols (C14, C16, and C18) esterified predominantly with odd carbon-numbered 2-methyl fatty acids (C7, C9, C11, and C13), resulting in relatively simple distributions. The even carbon-numbered wax esters show a far more complex distribution due to a number of factors: (i) Their n-alcohol moieties are not dominated by even carbon-numbered n-alcohols esterified with odd carbon-numbered 2-methyl fatty acids, but odd and even carbon-numbered n-alcohols participate in approximately equal amounts; (ii) odd carbon-numbered methyl-branched alcohols participate abundantly in these wax ester clusters; and (iii) with increasing molecular weight, various isomers of the 2,6-, 2,8-, and 2,10-dimethyl branched fatty acids also participate in the even carbon-numbered wax esters. The data demonstrate that there is a clear biosynthetic control on the wax ester composition although the reasons for the complex chemistry of the waxes are not yet understood. PMID:10907788

  4. Response to weaning and dietary L-glutamine supplementation: metabolomic analysis in piglets by gas chromatography/mass spectrometry.

    PubMed

    Xiao, Ying-ping; Wu, Tian-xing; Hong, Qi-hua; Sun, Jiang-ming; Chen, An-guo; Yang, Cai-mei; Li, Xiao-yan

    2012-07-01

    A novel metabolomic method based on gas chromatography/mass spectrometry (GC-MS) was applied to determine the metabolites in the serum of piglets in response to weaning and dietary L-glutamine (Gln) supplementation. Thirty-six 21-d-old piglets were randomly assigned into three groups. One group continued to suckle from the sows (suckling group), whereas the other two groups were weaned and their diets were supplemented with 1% (w/w) Gln or isonitrogenous L-alanine, respectively, representing Gln group or control group. Serum samples were collected to characterize metabolites after a 7-d treatment. Results showed that twenty metabolites were down-regulated significantly (P<0.05) in control piglets compared with suckling ones. These data demonstrated that early weaning causes a wide range of metabolic changes across arginine and proline metabolism, aminosugar and nucleotide metabolism, galactose metabolism, glycerophospholipid metabolism, biosynthesis of unsaturated fatty acid, and fatty acid metabolism. Dietary Gln supplementation increased the levels of creatinine, D-xylose, 2-hydroxybutyric acid, palmitelaidic acid, and ?-L-galactofuranose (P<0.05) in early weaned piglets, and were involved in the arginine and proline metabolism, carbohydrate metabolism, and fatty acid metabolism. A leave-one-out cross-validation of random forest analysis indicated that creatinine was the most important metabolite among the three groups. Notably, the concentration of creatinine in control piglets was decreased (P=0.00001) compared to the suckling piglets, and increased (P=0.0003) in Gln-supplemented piglets. A correlation network for weaned and suckling piglets revealed that early weaning changed the metabolic pathways, leading to the abnormality of carbohydrate metabolism, amino acid metabolism, and lipid metabolism, which could be partially improved by dietary Gln supplementation. These findings provide fresh insight into the complex metabolic changes in response to early weaning and dietary Gln supplementation in piglets. PMID:22761248

  5. Applications of Hadamard transform to gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry.

    PubMed

    Lin, Cheng-Huang; Kaneta, Takashi; Chen, Hung-Ming; Chen, Wen-Xiong; Chang, Hung-Wei; Liu, Ju-Tsung

    2008-08-01

    Successful application of the Hadamard transform (HT) technique to gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS) is described. Novel sample injection devices were developed to achieve multiple sample injections in both GC and LC instruments. Air pressure was controlled by an electromagnetic valve in GC, while a syringe pump and Tee connector were employed for the injection device in LC. Two well-known, abused drugs, 3,4-methylenedioxy-N-methylamphetamine (MDMA) and N, N-dimethyltryptamine (DMT), were employed as model samples. Both of the injection devices permitted precise successive injections, resulting in clearly modulated chromatograms encoded by Hadamard matrices. After inverse Hadamard transformation of the encoded chromatogram, the signal-to-noise (S/N) ratios of the signals were substantially improved compared with those expected from theoretical values. The S/N ratios were enhanced approximately 10-fold in HT-GC/MS and 6.8 in HT-LC/MS, using the matrices of 1023 and 511, respectively. The HT-GC/MS was successfully applied to the determination of MDMA in the urine sample of a suspect. PMID:18570388

  6. Analysis of Indole Alkaloids from Rhazya stricta Hairy Roots by Ultra-Performance Liquid Chromatography-Mass Spectrometry.

    PubMed

    Akhgari, Amir; Laakso, Into; Seppänen-Laakso, Tuulikki; Yrjönen, Teijo; Vuorela, Heikki; Oksman-Caldentey, Kirsi-Marja; Rischer, Heiko

    2015-01-01

    Rhazya stricta Decne. (Apocynaceae) contains a large number of terpenoid indole alkaloids (TIAs). This study focused on the composition of alkaloids obtained from transformed hairy root cultures of R. stricta employing ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). In the UPLC-MS analyses, a total of 20 TIAs were identified from crude extracts. Eburenine and vincanine were the main alkaloids followed by polar glucoalkaloids, strictosidine lactam and strictosidine. Secodine-type alkaloids, tetrahydrosecodinol, tetrahydro- and dihydrosecodine were detected too. The occurrence of tetrahydrosecodinol was confirmed for the first time for R. stricta. Furthermore, two isomers of yohimbine, serpentine and vallesiachotamine were identified. The study shows that a characteristic pattern of biosynthetically related TIAs can be monitored in Rhazya hairy root crude extract by this chromatographic method. PMID:26694342

  7. Analysis of polyphenolic antioxidants from the fruits of three pouteria species by selected ion monitoring liquid chromatography-mass spectrometry.

    PubMed

    Ma, Jun; Yang, Hui; Basile, Margaret J; Kennelly, Edward J

    2004-09-22

    Pouteria campechiana, Pouteria sapota, and Pouteria viridis are tropical plants in the Sapotaceae family that bear edible fruits. The fresh fruits of these three Pouteria species were each extracted, and activity-guided fractionations were performed to identify the antioxidant constituents. Seven polyphenolic antioxidants, gallic acid (1), (+)-gallocatechin (2), (+)-catechin (3), (-)-epicatechin (4), dihydromyricetin (5), (+)-catechin-3-O-gallate (6), and myricitrin (7), were isolated and identified. Extracts of the three Pouteria fruits were analyzed by a selected ion monitoring liquid chromatography-mass spectrometry method to quantify their polyphenolic antioxidants. The highest level of the seven measured polyphenols was found in P. sapota, the second highest in P. viridis, and the lowest in P. campechiana. The levels of the seven polyphenols corresponded with the results of the 1,1-diphenyl-2-picrylhydrazyl assay, by which P. sapota had the highest antioxidant activity, P. viridis the second highest, and P. campechiana the lowest. PMID:15366835

  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%, 800μgg(-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 247μgg(-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 2400μgg(-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. 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.

  10. Tandem Extraction/Liquid Chromatography-Mass Spectrometry Protocol for the Analysis of Acrylamide and Surfactant-related Compounds in Complex Aqueous Environmental Samples

    EPA Science Inventory

    The development of a liquid chromatography?mass spectrometry (LC?MS)?based strategy for the detection and quantitation of acrylamide and surfactant?related compounds in aqueous complex environmental samples.

  11. 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; 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 to 129 percent and RSDs ranging from 5 to 25 percent for low-level and high-level surface water spikes. The remaining compounds had poor mean recoveries (130 percent), or high RSDs (>29 percent) for these spikes. For wastewater, 14 of the compounds included in the unfiltered method had mean recoveries ranging from 62 to 127 percent and RSDs 130 percent), or low mean recoveries (33 percent) for the low-level wastewater spikes. Of the compounds found in wastewater, 24 had mean set spike recoveries ranging from 64 to 104 percent and RSDs Separate method detection limits (MDLs) were computed for surface water and wastewater for both the filtered and unfiltered methods. Filtered method MDLs ranged from 0.007 to 0.14 microgram per liter (μg/L) for the surface water matrix and from 0.004 to 0.62 μg/L for the wastewater matrix. Unfiltered method MDLs ranged from 0.014 to 0.33 μg/L for the surface water matrix and from 0.008 to 0.36 μg/L for the wastewater matrix.

  12. 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

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

    SciTech Connect

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

    2008-11-13

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

  14. 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.

  15. Rapid and sensitive method for analysis of nitrate in meat samples using ultra performance liquid chromatography-mass spectrometry.

    PubMed

    Siddiqui, Masoom Raza; Wabaidur, Saikh Mohammad; ALOthman, Zeid A; Rafiquee, M Z A

    2015-12-01

    A sensitive and selective ultra performance liquid chromatography-mass spectrometric method has been developed for the quantitative analysis of nitrate in meat samples. Selected ion reaction (SIR) mode was adopted to identify and quantify the nitrate. Chromatographic analyses were performed on a BEH C-18 column with a mobile phase consisting of a surfactant (Cetylpyridinium chloride) and acetonitrile in equal ratio (50/50, v/v) at a flow rate of 0.4 mL min(-1). The limit of detection and limit of quantitation of the developed method was found to be 0.0599 and 0.1817 mg kg(-1), respectively. The linearity of the proposed method was checked in the concentration range of 0.5-10 mg kg(-1) with an excellent correlation coefficient (r) of 0.997. The recovery of the nitrate in the meat samples were in the range of 98.02-98.99%. PMID:26184470

  16. Analysis of volatile organic compounds in human saliva by a static sorptive extraction method and gas chromatography-mass spectrometry.

    PubMed

    Soini, Helena A; Klouckova, Iveta; Wiesler, Donald; Oberzaucher, Elisabeth; Grammer, Karl; Dixon, Sarah J; Xu, Yun; Brereton, Richard G; Penn, Dustin J; Novotny, Milos V

    2010-09-01

    Human saliva not only helps control oral health (with anti-microbial proteins), but it may also play a role in chemical communication. As is the case with other mammalian species, human saliva contains peptides, proteins, and numerous volatile organic compounds (VOCs). A high-throughput analytical method is described for profiling a large number of saliva samples to screen the profiles of VOCs. Saliva samples were collected in a non-stimulated fashion. The method utilized static stir bar extraction followed by gas chromatography-mass spectrometry (GC-MS). The method provided excellent reproducibility for a wide range of salivary compounds, including alcohols, aldehydes, ketones, carboxylic acids, esters, amines, amides, lactones, and hydrocarbons. Furthermore, substantial overlap of salivary VOCs and the previously reported skin VOCs in the same subject group was found in this study by using pattern recognition analyses. Sensitivity, precision, and reproducibility of the method suggest that this technique has potential in physiological, metabolomic, pharmacokinetic, forensic, and toxicological studies of small organic compounds where a large number of human saliva samples are involved. PMID:20809147

  17. Hydrogenation Reactions during Pyrolysis-Gas Chromatography/Mass Spectrometry Analysis of Polymer Samples Using Hydrogen Carrier Gas.

    PubMed

    Watanabe, Atsushi; Watanabe, Chuichi; Freeman, Robert R; Teramae, Norio; Ohtani, Hajime

    2016-05-17

    Pyrolysis-gas chromatography/mass spectrometry of polymer samples is studied focusing on the effect of hydrogen (H2) carrier gas on chromatographic and spectral data. The pyrograms and the related mass spectra of high density polyethylene (HDPE), low density polyethylene, and polystyrene (PS) serve to illustrate the differences between the species formed in H2 and the helium environment. Differences in the pyrograms and the spectra are generally thought to be a result of the hydrogenation reaction of the pyrolyzates. From the peak intensity changes in the pyrograms of HDPE and PS, hydrogenation of unsaturated pyrolyzates is concluded to occur when the pyrolysis is done in H2. Moreover, additional hydrogenation of the pyrolyzates occurs in the electron ionization source of a MS detector when H2 is used as a carrier gas. Finally, the applicability of mass spectral libraries to characterize pyrograms obtained in H2 is illustrated using 24 polymers. The effect of the hydrogenation reaction on the library search results is found to be negligible for most polymer samples with polar and nonpolar monomer units. PMID:27125864

  18. Analysis of Trace Quaternary Ammonium Compounds (QACs) in Vegetables Using Ultrasonic-Assisted Extraction and Gas Chromatography-Mass Spectrometry.

    PubMed

    Xiang, Lei; Wang, Xiong-Ke; Li, Yan-Wen; Huang, Xian-Pei; Wu, Xiao-Lian; Zhao, Hai-Ming; Li, Hui; Cai, Quan-Ying; Mo, Ce-Hui

    2015-08-01

    A reliable, sensitive, and cost-effective method was developed for determining three quaternary ammonium compounds (QACs) including dodecyltrimethylammonium chloride, cetyltrimethylammonium chloride, and didodecyldimethylammonium chloride in various vegetables using ultrasonic-assisted extraction and gas chromatography-mass spectrometry. The variety and acidity of extraction solvents, extraction times, and cleanup efficiency of sorbents were estimated to obtain an optimized procedure for extraction of the QACs in nine vegetable matrices. Excellent linearities (R(2) > 0.992) were obtained for the analytes in the nine matrices. The limits of detection and quantitation were 0.7-6.0 and 2.3-20.0 ?g/kg (dry weight, dw) in various matrices, respectively. The recoveries in the nine matrices ranged from 70.5% to 108.0% with relative standard deviations below 18.0%. The developed method was applied to determine the QACs in 27 vegetable samples collected from Guangzhou in southern China, showing very high detection frequency with a concentration of 23-180 ?g/kg (dw). PMID:26165915

  19. Quantitative ester analysis in cachaca and distilled spirits by gas chromatography-mass spectrometry (GC-MS).

    PubMed

    Nascimento, Eduardo S P; Cardoso, Daniel R; Franco, Douglas W

    2008-07-23

    An analytical procedure for the separation and quantification of ethyl acetate, ethyl butyrate, ethyl hexanoate, ethyl lactate, ethyl octanoate, ethyl nonanoate, ethyl decanoate, isoamyl octanoate, and ethyl laurate in cachaca, rum, and whisky by direct injection gas chromatography-mass spectrometry was developed. The analytical method is simple, selective, and appropriated for the determination of esters in distilled spirits. The limit of detection ranged from 29 (ethyl hexanoate) to 530 (ethyl acetate) microg L(-1), whereas the standard deviation for repeatability was between 0.774% (ethyl hexanoate) and 5.05% (isoamyl octanoate). Relative standard deviation values for accuracy vary from 90.3 to 98.5% for ethyl butyrate and ethyl acetate, respectively. Ethyl acetate was shown to be the major ester in cachaca (median content of 22.6 mg 100 mL(-1) anhydrous alcohol), followed by ethyl lactate (median content of 8.32 mg 100 mL(-1) anhydrous alcohol). Cachaca produced in copper and hybrid alembic present a higher content of ethyl acetate and ethyl lactate than those produced in a stainless-steel column, whereas cachaca produced by distillation in a stainless-steel column present a higher content of ethyl octanoate, ethyl decanoate, and ethyl laurate. As expected, ethyl acetate is the major ester in whiskey and rum, followed by ethyl lactate for samples of rum. Nevertheless, whiskey samples exhibit ethyl lactate at contents lower or at the same order of magnitude of the fatty esters. PMID:18570431

  20. Analysis of ammonium nitrate headspace by on-fiber solid phase microextraction derivatization with gas chromatography mass spectrometry.

    PubMed

    Lubrano, Adam L; Andrews, Benjamin; Hammond, Mark; Collins, Greg E; Rose-Pehrsson, Susan

    2016-01-15

    A novel analytical method has been developed for the quantitation of trace levels of ammonia in the headspace of ammonium nitrate (AN) using derivatized solid phase microextraction (SPME) fibers with gas chromatography mass spectrometry (GC-MS). Ammonia is difficult to detect via direct injection into a GC-MS because of its low molecular weight and extreme polarity. To circumvent this issue, ammonia was derivatized directly onto a SPME fiber by the reaction of butyl chloroformate coated fibers with the ammonia to form butyl carbamate. A derivatized externally sampled internal standard (dESIS) method based upon the reactivity of diethylamine with unreacted butyl chloroformate on the SPME fiber to form butyl diethylcarbamate was established for the reproducible quantification of ammonia concentration. Both of these compounds are easily detectable and separable via GC-MS. The optimized method was then used to quantitate the vapor concentration of ammonia in the headspace of two commonly used improvised explosive device (IED) materials, ammonium nitrate fuel oil (ANFO) and ammonium nitrate aluminum powder (Ammonal), as well as identify the presence of additional fuel components within the headspace. PMID:26718189

  1. Quantitative analysis of exogenous peptides in plasma using immobilized enzyme cleavage and gas chromatography-mass spectrometry with negative ion chemical ionization.

    PubMed

    Márquez, C D; Lee, M L; Weintraub, S T; Smith, P C

    1997-10-24

    A method is presented for the analysis of peptides in plasma at picomole to femtomole levels. Peptides are isolated from plasma by solid-phase extraction, the peptide of interest is purified by reversed-phase high-performance liquid chromatography (HPLC) and selectively digested using immobilized trypsin or chymotrypsin to yield specific di- or tripeptides. These di- and tripeptides are esterified using heptafluorobutyric anhydride, alkylated with pentafluorobenzyl bromide, then quantified by gas chromatography-mass spectrometry with negative ion chemical ionization. This method has been evaluated for a model synthetic heptapeptide, using a deuterium labeled analog as an internal standard. The half-life of the heptapeptide in human plasma was found to be 2 min. Extraction efficiencies of a tritiated peptide of similar size to the heptapeptide, [3H]DSLET, from plasma using either C18 or strong cation-exchange columns were 85+/-3 and 70+/-2%, respectively. Quantitation of fragments from the heptapeptide indicated that the analysis was linear from 1-50 ng of the heptapeptide per ml of plasma. This method was subsequently employed for pharmacokinetic studies of the biologically active peptide Met-enkephalin-Arg-Gly-Leu, where linearity was obtained from 50 to 1000 ng/ml in rat plasma. This method demonstrated negligible side reaction by-products due to autolysis, and has potential for extensive use given the wide availability of gas chromatography-mass spectrometry. PMID:9390710

  2. Selective pressurized liquid extraction of estrogenic compounds in soil and analysis by gas chromatography-mass spectrometry.

    PubMed

    Zhang, Zulin; Rhind, Stewart M; Kerr, Christine; Osprey, Mark; Kyle, Carol E

    2011-01-24

    A selective pressurized liquid extraction (SPLE) method, followed by gas chromatography-mass spectrometry (GC-MS), for the simultaneous extraction and clean-up of estrone (E1), 17?-estradiol (E2), 17?-ethynylestradiol (EE2), estriol (E3) and bisphenol A (BPA) from soil samples is described. The on-line clean-up of soil by SPLE was achieved using different organic matter retainers, including silica, alumina and Florisil, the most effective being silica. Thus, different amounts of silica, in conjunction with different extraction solvents (acetone, ethyl acetate, isohexane and dichloromethane), either alone or in combination, were used to extract the target chemicals from spiked soil samples. It was shown that 3g silica resulted in satisfactory rates of recovery of target compounds and acetone:dichloromethane (1:3, v/v) was efficient in extracting and eluting estrogenic compounds for SPLE. Variables affecting the SPLE efficiency, including temperature and pressure were studied; the optimum parameters were 60C and 1500 psi, respectively. The limits of detection (LODs) of the proposed method were 0.02-0.37 ng g(-1) for the different estrogenic chemicals studied. The outputs using the proposed method were linear over the range from 0.1 to 120 ng g(-1) for E1, E2, EE2, 0.2-120 ng g(-1) for E3, and 0.5-120 ng g(-1) for BPA. The optimized method was further verified by performing spiking experiments in natural soil matrices; good rates of recovery and reproducibility were achieved for all selected compounds and the method was successfully applied to soil samples from Northeast Scotland, for the determination of the target compounds. PMID:21168548

  3. Analysis of odour compounds from scented consumer products using gas chromatography-mass spectrometry and gas chromatography-olfactometry.

    PubMed

    Bartsch, Jennifer; Uhde, Erik; Salthammer, Tunga

    2016-01-21

    Scented consumer products are being bought in increasing amounts and gaining more popularity. There is, however, relatively little information available about their ingredients, emissions and allergenic potential. Frequently, a mixture of different fragrance substances and not solely an individual substance contributes to the overall desired smell. The aim of this study was to investigate the odorous volatile organic compounds (OVOCs) in consumer products containing fragrances. Over 44 products were selected: various scented candles, printing products with different scent types and other products types particularly meant to be used indoors. Measurements were carried out in a desiccator. Air samples were collected on thermal desorption tubes to determine the released fragrance substances by means of gas chromatography-mass spectrometry (GC-MS). Moreover, gas chromatography-olfactometry (GC-O) was used to obtain sensory data and to ensure no important odorant was overlooked. Using both methods it was possible to distinguish between odour active and inactive compounds and subsequently to identify almost 300 different odorants across all scented products. Besides the advantage of differentiation, as the human nose is a very sensitive detector, GC-O was found to be a useful tool for detecting traces and chosen target compounds. One focus in this study lay on the 26 EU-regulated fragrance allergens to prove their relevance in scented consumer goods. In total, 18 of them were identified, with at least one substance being present in almost every product. Benzyl alcohol, cinnamaldehyde, citronellol, eugenol, linalool and limonene were the prevalently detected allergens. Particularly linalool and limonene were observed in over 50% of the products. In addition, eugenol appeared to be one of the most frequently detected compounds in trace-level concentrations in the candle emissions. PMID:26724768

  4. Microextraction and Gas Chromatography/Mass Spectrometry for improved analysis of geosmin and other fungal "off" volatiles in grape juice.

    PubMed

    Morales-Valle, H; Silva, L C; Paterson, R R M; Oliveira, J M; Venâncio, A; Lima, N

    2010-10-01

    Geosmin is a volatile fungal metabolite with an earthy aroma produced in grape products from rotten grapes. The accumulation of geosmin in grapes is caused by the interaction of Botrytis cinerea and Penicillium expansum. Solid Phase Microextraction (SPME) has great utility for collecting volatile compounds in wine. However, contamination with earthy odours may have occurred previously in the must and novel methods are required for this commodity. In the present report, several parameters of the SPME were evaluated to optimize geosmin extraction. The method permitted quantification of geosmin and other fungal volatiles by Gas Chromatography-Mass Spectrometer (GC-MS) at very low concentrations. Limits of detection and quantification (L(D) and L(Q)) for geosmin were 4.7 ng L(-1) and 15.6 ng L(-1) respectively. The RSD was 4.1% and the recovery rates ranged from 115% to 134%. Uniquely, haloanisoles were analyzed by using only one internal standard (2,3,6-trichloroanisole) thus avoiding the synthesis of deuterated anisole analogues that are used as internal standard in other methods. The method was used for the analysis of grape juice samples inoculated with B. cinerea and P. expansum. Geosmin and methylisoborneol were the compounds that appeared to contribute most to earthy odours, although other fungal compounds which are claimed to cause earthy or mouldy off-odours were detected (e.g. 1-octen-3-ol and fenchol). PMID:20655340

  5. Specialized Gas Chromatography--Mass Spectrometry Systems for Clinical Chemistry.

    ERIC Educational Resources Information Center

    Gochman, Nathan; And Others

    1979-01-01

    A discussion of the basic design and characteristics of gas chromatography-mass spectrometry systems used in clinical chemistry. A comparison of three specific systems: the Vitek Olfax IIA, Hewlett-Packard HP5992, and Du Pont DP-102 are included. (BB)

  6. Liquid Chromatography-Mass Spectrometry-based Quantitative Proteomics

    SciTech Connect

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

    2011-07-22

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

  7. Characterization of monoclonal antibodies by a fast and easy liquid chromatography-mass spectrometry time-of-flight analysis on culture supernatant.

    PubMed

    Henninot, Antoine; Terrier, Aurelie; Charton, Julie; Urbain, Rmi; Fontayne, Alexandre; Deprez, Benoit; Beghyn, Terence

    2015-12-15

    Rapid and efficient structural analysis is key to the development of new monoclonal antibodies. We have developed a fast and easy process to obtain mass spectrometry profiles of antibodies from culture supernatant. Treatment of the supernatant with IdeS generates three fragments of 25kDa that can be analyzed by liquid chromatography-mass spectrometry time-of-flight (LC-MS TOF) in one run: LC, Fd, and Fc/2. This process gives rapid access to isoform and glycoform profiles. To specifically measure the fucosylation yield, we included a one-pot treatment with EndoS that removes the distal glycan heterogeneity. Our process was successfully compared with high-performance capillary electrophoresis with laser-induced fluorescence detection (HPCE-LIF), currently considered as the "gold standard" method. PMID:26302360

  8. Trimethylsilyl speciations of cathine, cathinone and norephedrine followed by gas chromatography mass spectrometry: Direct sample preparation and analysis of khatamines.

    PubMed

    Molnár, Borbála; Fodor, Blanka; Boldizsár, Imre; Molnár-Perl, Ibolya

    2016-04-01

    A literature criticism is given on methods using currently gas chromatography mass spectrometry (GC/MS) to determine cathine (CAT), cathinone (CTN) and norephedrine (NE), jointly khatamines. In this study, khatamines' oximation, trimethylsilylation and mass fragmentation properties-applying N-Methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA), its trimethyliodosilane (TMIS) catalyst containing version (MSTFA(TMIS)), N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and hexamethyldisilazane (HMDS)-was highlighted, at first. Derivatization, mass fragmentation and quantitation related, optimized model investigations have been carried out as a function of the reaction times and conditions. Special emphasis was put (i) on the stability of the primarily formed (CAT-2TMS, NE-2TMS, CTN-TMS(TMS-oximes)1,2), then transformed, fully derived (CAT-3TMS, NE-3MTS, CTN-2TMS(TMS-oximes)1,2) species, and, (ii) on the proportionally formed stable products, suitable to selective quantitation of all three natural amines, simultaneously. Results, as novelty to the field confirmed that (i) TMIS catalyzed trimethylsilyation triggers to form fully derivatized species unfortunately, in part only; while, (ii) khatamines' simultaneous quantitation needs to be carried out in a two steps derivatization process consisting of oximation (1st step, hydroxylamine in pyridine) and trimethylsilylation (2nd step, MSTFA), to the CAT-2TMS, NE-2TMS, CTN-TMS(TMS-oximes)1,2. These species were characterized with their retention, mass fragmentation and analytical performance properties, in model solutions and in the presence of plant tissues, as well: R(2), limit of quantitation (LOQ) data, expressed in pg/1μL injection basis, proved to be 62.5pg (CAT), 20pg (NE) and 62.5pg (CTN), respectively. The practical utility of proposal was enormously enhanced by the novel, direct sample preparation method. In this process, the freshly harvested, freeze-dried, then pulverized leaves of Catha edulis FORKS were directly derivatized, in the presence of the matrix. Reproducibility (in average 2.07 RSD% varying between 0.15 and 5.5 RSD%), linearity (0.9990-0.9994) and recovery (95.7-99.1%) values of the new sample preparation protocol was confirmed by the standard addition method for CAT, NE and CTN equally. From plant leaf, 0.061w/w% CAT and 0.014w/w% NE contents were obtained. In this tissue CTN was not found. Very likely attributable to the unfavorable climate for the plant: grown in Hungary of temperate zone and naturalized in the tropical Africa. PMID:26928873

  9. Study of the precision in the purge-and-trap-gas chromatography-mass spectrometry analysis of volatile compounds in honey.

    PubMed

    Soria, Ana Cristina; Martínez-Castro, Isabel; Sanz, Jesús

    2009-04-10

    Data precision in the analysis by purge-and-trap coupled on-line to gas chromatography-mass spectrometry (P&T-GC-MS) of honey volatiles has been studied by statistical analysis. The contribution of non-random factors to dispersion of quantitative results was proven by comparing several statistical parameters (correlation coefficients, principal component analysis (PCA) eigenvalues and loadings) from both experimental and simulated data. PCA was also useful for grouping volatiles with similar dispersion behaviour; these groups being generally related to compounds with common properties or structural features. The use of area ratios improves data precision for compounds within the same group. Results from this study could be used for a better selection of internal standards in quantitative analysis of volatiles by P&T-GC-MS. PMID:19203763

  10. Comparison of gas chromatography-mass spectrometry and gas chromatography-combustion-isotope ratio mass spectrometry analysis for in vivo estimates of metabolic fluxes.

    PubMed

    Croyal, Mikaël; Bourgeois, Raphaëlle; Ouguerram, Khadija; Billon-Crossouard, Stéphanie; Aguesse, Audrey; Nguyen, Patrick; Krempf, Michel; Ferchaud-Roucher, Véronique; Nobécourt, Estelle

    2016-05-01

    Gas chromatography-mass spectrometry (GC-MS) was compared with gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) for measurements of cholesterol (13)C enrichment after infusion of labeled precursor ([(13)C1,2]acetate). Paired results were significantly correlated, although GC-MS was less accurate than GC-C-IRMS for higher enrichments. Nevertheless, only GC-MS was able to provide information on isotopologue distribution, bringing new insights to lipid metabolism. Therefore, we assessed the isotopologue distribution of cholesterol in humans and dogs known to present contrasted cholesterol metabolic pathways. The labeled tracer incorporation was different in both species, highlighting the subsidiarity of GC-MS and GC-C-IRMS to analyze in vivo stable isotope studies. PMID:26898306

  11. Rapid analysis of fatty acid profiles in raw nuts and seeds by microwave-ultrasonic synergistic in situ extraction-derivatisation and gas chromatography-mass spectrometry.

    PubMed

    Liu, Rui-Lin; Song, Shuang-Hong; Wu, Mei; He, Tian; Zhang, Zhi-Qi

    2013-12-15

    Based on microwave-ultrasonic synergistic in situ extraction-derivatisation (MUED), gas chromatography-mass spectrometry was proposed for rapid analysis of fatty acid profiles in raw nut and seed materials. Several critical experimental parameters for MUED, including reaction temperature, microwave power, amounts of catalyst and derivatisation reagent, have been optimised using response surface methodology. The results showed that the chromatographic peak areas of total fatty acids and the content of total unsaturated fatty acids obtained with MUED were markedly higher than those obtained by the conventional method (P<0.05 and P<0.01, respectively). The MUED method simplified the handling steps compared to the conventional procedure, shortened the sample preparation time whilst improving the extraction and derivatisation efficiency of lipids, and reduced oxidisation and decomposition of the unsaturated fatty acids. The simplicity, robustness and practicality of this method highlighted its significant potential for application in the rapid analysis of fatty acids in natural food resource samples. PMID:23993615

  12. Identification of polar organic compounds in coal-gasification condensate water by gas chromatography-mass spectrometry analysis of high-performance liquid chromatography fractions

    SciTech Connect

    Mohr, D.H.; King, C.J.

    1985-10-01

    A novel combination of analytical techniques was employed to identify polar organic compounds, including the first report of hydantoins, in condensate waters from a slagging fixed-bed coal-gasification process. The analytical technique consists of high-performance liquid chromatography (HPLC) separation and gas chromatography-mass spectrometry (GC-MS) analysis of HPLC fractions. Entrainer distillation was used to concentrate the HPLC fractions and remove water before GC-MS analysis. Analyses of four samples accounted for 69-84% of the measured chemical oxygen demand (COD), including 1-6% of the COD as dimethylhydantoin. This compound is highly polar and difficult to remove by solvent extraction. Other identified compounds included phenols, di-hydroxybenzenes, methanol, acetone, and acetonitrile. Many of the unidentified compounds (16-31% of the COD) were difficult to extract, had low volatility relative to water, and contained organic nitrogen. Some chemical changes were observed during storage of condensate water samples.

  13. 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

  14. Quantitative Analysis of Bisphenol A Leached from Household Plastics by Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry (SPME-GC-MS)

    ERIC Educational Resources Information Center

    Johnson, Bettie Obi; Burke, Fernanda M.; Harrison, Rebecca; Burdette, Samantha

    2012-01-01

    The measurement of trace levels of bisphenol A (BPA) leached out of household plastics using solid-phase microextraction (SPME) with gas chromatography-mass spectrometry (GC-MS) is reported here. BPA is an endocrine-disrupting compound used in the industrial manufacture of polycarbonate plastic bottles and epoxy resin can liners. This experiment…

  15. Quantitative Analysis of Bisphenol A Leached from Household Plastics by Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry (SPME-GC-MS)

    ERIC Educational Resources Information Center

    Johnson, Bettie Obi; Burke, Fernanda M.; Harrison, Rebecca; Burdette, Samantha

    2012-01-01

    The measurement of trace levels of bisphenol A (BPA) leached out of household plastics using solid-phase microextraction (SPME) with gas chromatography-mass spectrometry (GC-MS) is reported here. BPA is an endocrine-disrupting compound used in the industrial manufacture of polycarbonate plastic bottles and epoxy resin can liners. This experiment

  16. 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.; Petrović, 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 μg/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).

  17. Quantitative Analysis of Bioactive Compounds from Aromatic Plants by Means of Dynamic Headspace Extraction and Multiple Headspace Extraction-Gas Chromatography-Mass Spectrometry.

    PubMed

    Omar, Jone; Olivares, Maitane; Alonso, Ibone; Vallejo, Asier; Aizpurua-Olaizola, Oier; Etxebarria, Nestor

    2016-04-01

    Seven monoterpenes in 4 aromatic plants (sage, cardamom, lavender, and rosemary) were quantified in liquid extracts and directly in solid samples by means of dynamic headspace-gas chromatography-mass spectrometry (DHS-GC-MS) and multiple headspace extraction-gas chromatography-mass spectrometry (MHSE), respectively. The monoterpenes were 1st extracted by means of supercritical fluid extraction (SFE) and analyzed by an optimized DHS-GC-MS. The optimization of the dynamic extraction step and the desorption/cryo-focusing step were tackled independently by experimental design assays. The best working conditions were set at 30 °C for the incubation temperature, 5 min of incubation time, and 40 mL of purge volume for the dynamic extraction step of these bioactive molecules. The conditions of the desorption/cryo-trapping step from the Tenax TA trap were set at follows: the temperature was increased from 30 to 300 °C at 150 °C/min, although the cryo-trapping was maintained at -70 °C. In order to estimate the efficiency of the SFE process, the analysis of monoterpenes in the 4 aromatic plants was directly carried out by means of MHSE because it did not require any sample preparation. Good linearity (r(2 ) > 0.99) and reproducibility (relative standard deviation % <12) was obtained for solid and liquid quantification approaches, in the ranges of 0.5 to 200 ng and 10 to 500 ng/mL, respectively. The developed methods were applied to analyze the concentration of 7 monoterpenes in aromatic plants obtaining concentrations in the range of 2 to 6000 ng/g and 0.25 to 110 μg/mg, respectively. PMID:26925555

  18. Recent Trends in Sample Preparation and Liquid Chromatography/Mass Spectrometry for Pesticide Residue Analysis in Food and Related Matrixes.

    PubMed

    Rejczak, Tomasz; Tuzimski, Tomasz

    2015-01-01

    A rising interest by consumers and various governmental organizations towards the quality of food has been continuously observed. Pesticide residue analysis has a significant role in assessing food safety and quality. This article reviews the new analytical approaches for efficient extraction and reliable identification and quantification of pesticides in foodstuffs and related matrixes. Emphasis is given to the new materials used for effective extract purification. We discuss the potential and pitfalls of the different LC/MS approaches, including application of high resolution mass spectrometry in the area of pesticide residue analysis. Untargeted and retrospective screening is outlined, highlighting prospects and achievements as well as its major drawbacks. PMID:26525233

  19. Differentiation of flavonol glucoside and galactoside isomers combining chemical isopropylidenation with liquid chromatography-mass spectrometry analysis.

    PubMed

    de Souza, Lauro M; Dartora, Nessana; Scoparo, Camila T; Gorin, Philip A J; Iacomini, Marcello; Sassaki, Guilherme L

    2016-05-20

    Flavonol glycosides are important components of leaves from vascular plants. A lot of isomers of these compounds are produced by plants, making their analysis very difficult and causing many structural misinterpretations. Galactosides and glucosides as mono- or oligosaccharides yield many diastereoisomers, hindering the analysis by mass spectrometry. In order to enable the mass spectrometric distinctions of these isomers, in this work we combine an isopropylidene based chemical derivatization with liquid chromatography with multiple-stage mass spectrometry (LC-MS(n)) analysis. The isomers of flavonol triglycosides, after the reaction, yielded products with different molecular weight, therefore, they were no longer isomers, allowing their identification by MS(1) analysis. However, to the 4 isomers of flavonol diglycosides, only one yielded, after isopropylidenation, a product with different molecular weight. To the other 3 species, the incorporation of 2 isopropylidene groups retained them in the isomeric form. For such species, chromatographic separation and MS(n) detection targeting the lithium adducts of 3,4-O-isopropylidene-galactosyl or 4,6-O-isopropylidene-glucosyl residues (m/z 209.099) provided specific MS profile. PMID:27109198

  20. 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...

  1. A METHOD FOR AUTOMATED ANALYSIS OF 10 ML WATER SAMPLES CONTAINING ACIDIC, BASIC, AND NEUTRAL SEMIVOLATILE COMPOUNDS LISTED IN USEPA METHOD 8270 BY SOLID PHASE EXTRACTION COUPLED IN-LINE TO LARGE VOLUME INJECTION GAS CHROMATOGRAPHY/MASS SPECTROMETRY

    EPA Science Inventory

    Data is presented showing the progress made towards the development of a new automated system combining solid phase extraction (SPE) with gas chromatography/mass spectrometry for the single run analysis of water samples containing a broad range of acid, base and neutral compounds...

  2. 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

  3. Peak assignment in multi-capillary column-ion mobility spectrometry using comparative studies with gas chromatography-mass spectrometry for VOC analysis.

    PubMed

    Jünger, Melanie; Bödeker, Bertram; Baumbach, Jörg Ingo

    2010-01-01

    Over the past years, ion mobility spectrometry (IMS) as a well established method within the fields of military and security has gained more and more interest for biological and medical applications. This highly sensitive and rapid separation technique was crucially enhanced by a multi-capillary column (MCC), pre-separation for complex samples. In order to unambiguously identify compounds in a complex sample, like breath, by IMS, a reference database is mandatory. To obtain a first set of reference data, 16 selected volatile organic substances were examined by MCC-IMS and comparatively analyzed by the standard technique for breath research, thermal desorption-gas chromatography-mass spectrometry. Experimentally determined MCC and GC retention times of these 16 compounds were aligned and their relation was expressed in a mathematical function. Using this function, a prognosis of the GC retention time can be given very precisely according to a recorded MCC retention time and vice versa. Thus, unknown MCC-IMS peaks from biological samples can be assigned-after alignment via the estimated GC retention time-to analytes identified by GC/MS from equivalent accomplished data. One example of applying the peak assignment strategy to a real breath sample is shown in detail. PMID:19838827

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

    PubMed

    Lísa, Miroslav; Holčapek, 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 μm 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

  5. Application of gas chromatography-mass spectrometry metabolite profiling techniques to the analysis of heathland plant diets of sheep.

    PubMed

    Parveen, Ifat; Moorby, Jon M; Fraser, Mariecia D; Allison, Gordon G; Kopka, Joachim

    2007-02-21

    Little is known about how plant biochemistry influences the grazing behavior of animals consuming heterogeneous plant communities. The biochemical profiles of grassland species are mostly restricted to major nutritional characteristics, although recent developments in analytical techniques and data analysis have made possible the detailed analysis of minor components that may influence animal feeding preferences, performance, and health. In the present study, gas chromatography coupled with time-of-flight mass spectrometry (GC-TOF/MS) was used to profile the abundances of metabolites in nine specific heathland plant groups and in three mixed forage diets containing 10, 20, or 30% heather (Calluna vulgaris) and also in plasma and feces from sheep offered one of the three diets. Statistical and chemometric approaches, that is, principal component analysis (PCA) and hierarchical cluster analysis (HCA), were used to discriminate between these diets and between individual animals maintained on these diets. It is shown that GC-TOF/MS analysis of sheep plasma allowed distinction between the very similar diets by PCA and HCA, and, moreover, the plant metabolites responsible for the differences observed have been identified. Furthermore, metabolite markers of herbage mixtures and individual plant groups have been identified, and markers have been detected in sheep plasma and feces. PMID:17249687

  6. [Analysis of volatile and non-volatile compositions in ginger oleoresin by gas chromatography-mass spectrometry].

    PubMed

    Zhan, Kunyou; Wang, Chao; Xu, Kun; Yin, Hongzong

    2008-11-01

    Ginger oleoresin was extracted from Zingiber officinale Rose. var. Laiwudajiang by the technique of supercritical fluid extraction. Gas chromatography and mass spectrometry technique were employed to analyze the ginger oleoresin. This analysis resulted in the detection of 3 hitherto unknown natural compounds, 24 compounds previously reported as pungent compounds and 50 volatile compounds from ginger. The volatile compounds were mainly alpha-zingiberene (22.29%), beta-sesquiphellandrene (8.58%), alpha-farnesene (3.93%), beta-bisabolene (3.87%), alpha-curcumene (2.63%), which were mostly consisted of sesquiterpene hydrocarbons. The pungent compounds of ginger were mainly 6-gingerol (9.38%), 6-shogaol (7.59%), zingerone (9.24%) produced by the thermal degradation of gingerols or shogaols. The mass spectral fragmentation patterns for the three new compounds (6-isogingerol, (Z)-10-isoshogaol, (E)-10-isoshogaol) are discussed and interpreted. PMID:19253546

  7. Chiral analysis of methadone and its major metabolites (EDDP and EMDP) by liquid chromatography-mass spectrometry.

    PubMed

    Kelly, Tamsin; Doble, Philip; Dawson, Michael

    2005-01-25

    Racemic methadone (MET) is administered to heroin users undergoing methadone maintenance therapy (MMT) in Australia. The enantiomers of methadone possess different pharmacological effects, and the enantioselective metabolism of methadone to its two major metabolites, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) and 2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline (EMDP) has been demonstrated. Therefore, a stereoselective method capable of quantifying methadone, EDDP and EMDP in biological samples could be of benefit in the monitoring of MMT patients. In particular, the analysis of hair samples would provide a means by which long-term monitoring of MMT patients could be achieved. To date, no HPLC method has been published for the simultaneous separation of the six enantiomers. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the chiral analysis of methadone, EDDP and EMDP was developed using an alpha-glycoprotein (AGP) stationary phase. The method development involved the utilisation of factorial analysis experimental designs and the application of artificial neural networks (ANNs) to model the chromatographic response surfaces. The optimal conditions were determined to be 20mM acetic acid: isopropanol (93:7, pH 7.4), with a flow rate of 0.9mL/min. The method was validated and subsequently applied to the analysis of 20 hair samples collected from MMT patients. PMID:15639454

  8. Liquid chromatography/mass spectrometry analysis of perfluoroalkyl carboxylic acids and perfluorooctanesulfonate in bivalve shells: extraction method optimization.

    PubMed

    Wang, Lei; Sun, Hongwen; Yang, Lurong; He, Chuan; Wu, Wenling; Sun, Shujuan

    2010-01-22

    Different extraction methods, including extraction by organic solvents with and without acetic acid digestion, and mixed inorganic acid digestion coupled with solid phase extraction (SPE), were developed for the analysis of perfluorinated carboxylic acids (PFCAs) and perfluorooctanesulfonate (PFOS) in bivalve shells. The extracts were separated, identified and quantified by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). The method utilizing mixed acid digestion coupled with SPE performed more efficiently than other extraction methods. Matrix recoveries of the optimized methods ranged from 92% to 104%, with limits of detection of 0.05-0.43ng/g. The optimized method was successfully applied to the analysis of PFCAs and PFOS in shell samples of two bivalves from Bohai Bay, China. PFCAs and PFOS concentrations in the shells ranged from 0.3 ng/g to 4.1 ng/g, 1-50 times lower than those in the soft tissues of bivalves for most target analytes. No relationship between PFCAs and PFOS in shells and in soft tissues was found; this is explained by the different contaminant uptake mechanism of shells and soft tissues. PMID:20015508

  9. Analysis of Essential Oil in Jerusalem Artichoke (Helianthus tuberosus L.) Leaves and Tubers by Gas Chromatography-Mass Spectrometry

    PubMed Central

    Helmi, Zead; Al Azzam, Khaldun Mohammad; Tsymbalista, Yuliya; Ghazleh, Refat Abo; Shaibah, Hassan; Aboul-Enein, Hassan

    2014-01-01

    Purpose: To investigate, for the first time, the chemical composition of essential oil of the tubers and leaves of Jerusalem artichoke (Helianthus tuberosus L.), a species of sunflower native to eastern North America, growing in Ukraine. Methods: A hydrodistillation apparatus was used for the extraction of volatile components and then it was analysed by gas chromatography equipped with a split-splitless injector (split ratio, 1:50) and flame ionization detector (FID). The oil was analyzed under linear temperature programming applied at 4°C/min from 50°C - 340°C. Temperatures of the injector and FID detector were maintained at 280°C and 300°C, respectively. The chemical analysis of the oil was carried out using gas chromatography coupled to mass spectrometry (GC-MS), to determine the chemical composition of the volatile fraction. Results: The essential oils content ranged from 0.00019 to 0.03486 and 0.00011 to 0.00205 (g/100g), in leaves and tubers, respectively. The qualitative and quantitative analysis led to the identification of 17 components in both species samples. The major component found in leaves and tubers was (-)-β-bisabolene with 70.7% and 63.1%, respectively. Conclusion: Essential oil profile of Jerusalem artichoke species showed significant differences between leaves and tubers species. Additionally, the leaves of Jerusalem artichoke are a promising source of natural β-bisabolene. PMID:25671184

  10. Ultra-high performance liquid chromatography-mass spectrometry for the metabolomic analysis of urine in colorectal cancer.

    PubMed

    Ma, Yan-Lei; Qin, Huan-Long; Liu, Wei-Jie; Peng, Jia-Yuan; Huang, Long; Zhao, Xiao-Ping; Cheng, Yi-Yu

    2009-12-01

    We report here the results of a pilot study in which ultra-high performance liquid chromatography/time-of- flight-mass spectrometry (UPLC/TOF-MS) and multivariate statistical analysis (supervised partial least squares discriminant analysis, PLS-DA) were applied for urinary metabolite profiling and data interpretation. The results of the PLS-DA indicated that the metabolic pattern as a whole was significantly different between the groups of preoperative colorectal cancer (CRC) patients, postoperative CRC patients, and healthy volunteers, respectively. The preoperative group of patients showed significantly increased levels of low-molecular weight compounds (LMC) MW 283 and MW 234 in comparison to the group of healthy volunteers group. After the operation, the levels of these two LMC significantly decreased. These preliminary results suggest that the UPLC-MS-based method coupled with pattern recognition will likely lead to procedures with the potential to be clinically applicable for the diagnosis of CRC and, consequently, to an improvement in patient prognosis. PMID:19117128

  11. Identification of Synthetic Polymers and Copolymers by Analytical Pyrolysis-Gas Chromatography/Mass Spectrometry

    ERIC Educational Resources Information Center

    Kusch, Peter

    2014-01-01

    An experiment for the identification of synthetic polymers and copolymers by analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was developed and performed in the polymer analysis courses for third-year undergraduate students of chemistry with material sciences, and for first-year postgraduate students of polymer sciences. In…

  12. Identification of Synthetic Polymers and Copolymers by Analytical Pyrolysis-Gas Chromatography/Mass Spectrometry

    ERIC Educational Resources Information Center

    Kusch, Peter

    2014-01-01

    An experiment for the identification of synthetic polymers and copolymers by analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was developed and performed in the polymer analysis courses for third-year undergraduate students of chemistry with material sciences, and for first-year postgraduate students of polymer sciences. In

  13. Multidimensional proteomic analysis of photosynthetic membrane proteins by liquid extraction-ultracentrifugation-liquid chromatography-mass spectrometry.

    PubMed

    Huber, Christian G; Walcher, Wolfgang; Timperio, Anna-Maria; Troiani, Sonia; Porceddu, Andrea; Zolla, Lello

    2004-12-01

    The membrane protein components of photosystem I (PSI) and II (PSII) from different species were prefractionated by liquid extraction and sucrose gradient ultracentrifugation and subsequently analyzed by reversed-phase high-performance liquid chromatography-electrospray ionization-mass spectrometry (RP-HPLC-ESI-MS) using poly-(styrene-divinylbenzene)-based monolithic capillary columns. The analytical method was shown to be very flexible and enabled the identification of antenna proteins as well as most of the proteins of the reaction center from PSI and PSII in various plant species with few RP-HPLC-ESI-MS analyses necessitating only minor adaptations in the gradients of acetonitrile in 0.05% aqueous trifluoroacetic acid. The membrane proteins, ranging in molecular mass (Mr) from 4196 (I protein) to more than 80,000 (PSI A/B) as well as isoforms were identified on the basis of their intact Mr and comparison with Mr deduced from known DNA or protein sequences. High quality mass spectra enabled the identification and quantitation of the nonphosphorylated and phosphorylated reaction center subunits D1, D2, and CP43 of PSII, containing five to seven membrane-spanning alpha-helices. Because of its high flexibility and suitability for proteins having a very wide range of Mr and hydrophobicities, the method is generally applicable to the analysis of complex mixtures of membrane proteins. PMID:15449339

  14. [THE CHROMATOGRAPHY-MASS SPECTROMETRY ANALYSIS OF MICROBIAL FATTY ACIDS IN HUMAN BIOLOGICAL FLUIDS AND THEIR CLINICAL SIGNIFICANCE].

    PubMed

    Platonova, A G; Osipov, G A; Boiko, N B; Kirillova, N V; Rodionov, G G

    2015-12-01

    The technique of mass-spectrometric microbial markers is known for almost 20 years. The technique is described in a number of research publications, dissertations and methodological literature. It passed the registration in Roszdravnadzor and is permitted for implementation as a new medical technology in medical institutions on the territory of the Russian Federation ("The evaluation of microecological human status using technique of mass-spectrometry" license FS No 2010/038 of 24.02.2010). The technique of mass-spectrometric microbial markers began to be developed as instrument of clinical routine analysis and monitoring of microecological status, infection and disbiosises in clinical and out-patient practice. The description of technology of mass- spectrometric microbial markers in this aspect requires different than before approach to introduction of clinical laboratory assistants and physicians into technique application. The substantiation given concerning species specificity of composition of fatty acids and (fatty) aldehydes of cellular wall of microorganisms as a basis of their species differentiation in pure culture. The choice is explained concerning molecular markers for their detection in blood and other clinical material with the purpose of further reconstruction of composition of human microbial cenosis (microecology) on blood or calculation of composition of mixed infection in organs om samples of inflammation focus--urine, liquor, phlegm, exudate, drainage, and similar samples containing chemical information about microbes. PMID:27032254

  15. Analysis of paralytic shellfish toxins, potential chemical threat agents, in food using hydrophilic interaction liquid chromatography-mass spectrometry.

    PubMed

    Jansson, Daniel; Åstot, Crister

    2015-10-23

    A novel method for determining paralytic shellfish toxin (PST) profiles in food was developed using a combination of silica and strong cation exchange (SCX) solid phase extraction (SPE) coupled to hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS). Besides the risk for natural contamination of seafood and drinking water, PSTs also pose potent threats through intentional contamination of food, due to their high toxicity and the wide distributions of toxin-producing algae. The new preparation method aim to maintain the samples' original toxin profiles by avoiding conditions known to induce interconversion or degradation of the PSTs. The method was evaluated for PST extraction from water, milk, orange juice, apple purée, baby food, and blue mussels (Mytilus edulis). The extracts were found to produce reproducible retention times in HILIC-MS/MS analysis. When an authentic toxic mussel sample was analyzed using the novel method, saxitoxin and gonyautoxin-3 were identified, in agreement with data acquired using the Lawrence pre-column oxidation high-performance liquid chromatography-fluorescence detection (HPLC-FLD) method. Overall recoveries of the PSTs from tested foods by the novel method ranged from 36% to 111%. PMID:26404910

  16. Simultaneous analysis of some club drugs in whole blood using solid phase extraction and gas chromatography-mass spectrometry.

    PubMed

    Castro, André L; Tarelho, Sónia; Silvestre, Armando; Teixeira, Helena M

    2012-02-01

    The use of psychoactive substances to improve social relations and increase body energy, in Rave Culture, has raised many legal and health public concerns, both for illicit trade and consumption. Therefore, forensic toxicology plays an important role in this area, mainly linked to the detection and quantitation of these substances, both in vivo and in post-mortem samples. In fact, at the moment, forensic sciences have been under public authorities' scrutiny and critical look, due to the increasing attention of the media and public opinion, always applying for the use of scientific knowledge to help solving forensic cases. However, forensic toxicology results are only reliable to solve legal cases if all the analytical methodologies used are appropriately validated. In this work, a methodology for the extraction and analysis of 7-aminoflunitrazepam, buprenorphine, flunitrazepam, ketamine, methadone, phencyclidine (PCP) and d-propoxyphene was developed for whole blood samples, with solid phase extraction (SPE), using OASIS(®) MCX SPE columns, and gas chromatography coupled to mass spectrometry. The procedure presented here proved to be reliable, specific, selective and sensitive, with good LODs and LOQs and good precision.The adoption of a SPE procedure with an automatic SPE extraction device, allowed an increased level of automation in sample treatment, being contemporarily less time-consuming, increasing productiveness, and allowing good recovery and appropriate selectivity being, also, simple and reproducible. The simultaneous detection and quantitation of all compounds by the same extraction and detection methodology is crucial and has a great potential for forensic toxicology and clinical analysis. PMID:22281215

  17. 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?) 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

  18. Analysis of dextromethorphan and dextrorphan in decomposed skeletal tissues by microwave assisted extraction, microplate solid-phase extraction and gas chromatography- mass spectrometry (MAE-MPSPE-GCMS).

    PubMed

    Fraser, Candice D; Cornthwaite, Heather M; Watterson, James H

    2015-08-01

    Analysis of decomposed skeletal tissues for dextromethorphan (DXM) and dextrorphan (DXT) using microwave assisted extraction (MAE), microplate solid-phase extraction (MPSPE) and gas chromatography-mass spectrometry (GC-MS) is described. Rats (n = 3) received 100 mg/kg DXM (i.p.) and were euthanized by CO2 asphyxiation roughly 20 min post-dose. Remains decomposed to skeleton outdoors and vertebral bones were recovered, cleaned, and pulverized. Pulverized bone underwent MAE using methanol as an extraction solvent in a closed microwave system, followed by MPSPE and GC-MS. Analyte stability under MAE conditions was assessed and found to be stable for at least 60 min irradiation time. The majority (>90%) of each analyte was recovered after 15 min. The MPSPE-GCMS method was fit to a quadratic response (R(2)  > 0.99), over the concentration range 10-10 000 ng⋅mL(-1) , with coefficients of variation <20% in triplicate analysis. The MPSPE-GCMS method displayed a limit of detection of 10 ng⋅mL(-1) for both analytes. Following MAE for 60 min (80 °C, 1200 W), MPSPE-GCMS analysis of vertebral bone of DXM-exposed rats detected both analytes in all samples (DXM: 0.9-1.5 µg⋅g(-1) ; DXT: 0.5-1.8 µg⋅g(-1) ). PMID:25487525

  19. Seized cannabis seeds cultivated in greenhouse: A chemical study by gas chromatography-mass spectrometry and chemometric analysis.

    PubMed

    Mariotti, Kristiane de Cássia; Marcelo, Marcelo Caetano Alexandre; Ortiz, Rafael S; Borille, Bruna Tassi; Dos Reis, Monique; Fett, Mauro Sander; Ferrão, Marco Flôres; Limberger, Renata Pereira

    2016-01-01

    Cannabis sativa L. is cultivated in most regions of the world. In 2013, the Brazilian Federal Police (BFP) reported 220 tons of marijuana seized and about 800,000 cannabis plants eradicated. Efforts to eradicate cannabis production may have contributed to the development of a new form of international drug trafficking in Brazil: the sending of cannabis seeds in small amounts to urban centers by logistics postal. This new and increasing panorama of cannabis trafficking in Brazil, encouraged the chemical study of cannabis seeds cultivated in greenhouses by gas-chromatography coupled with mass spectrometry (GC-MS) associated with exploratory and discriminant analysis. Fifty cannabis seeds of different varieties and brands, seized by the BFP were cultivated under predefined conditions for a period of 4.5 weeks, 5.5 weeks, 7.5 weeks, 10 weeks and 12 weeks. Aerial parts were analyzed and cannabigerol, cannabinol, cannabidiol, cannabichromene Δ9-tetrahydrocannabinol (THC) and other terpenoids were detected. The chromatographic chemical profiles of the samples were significantly different, probably due to different variety, light exposition and age. THC content increased with the age of the plant, however, for other cannabinoids, this correlation was not observed. The chromatograms were plotted in a matrix with 50 rows (samples) and 3886 columns (abundance in a retention time) and submitted to PCA, HCA and PLS-DA after pretreatment (normalization, first derivative and autoscale). The PCA and HCA showed age separation between samples however it was not possible to verify the separation by varieties and brands. The PLS-DA classification provides a satisfactory prediction of plant age. PMID:26746824

  20. Microwave-assisted one-step extraction-derivatization for rapid analysis of fatty acids profile in herbal medicine by gas chromatography-mass spectrometry.

    PubMed

    Liu, Rui-Lin; Zhang, Jing; Mou, Zhao-Li; Hao, Shuang-Li; Zhang, Zhi-Qi

    2012-11-01

    A rapid and practical microwave-assisted one-step extraction-derivatization (MAED) method was developed for gas chromatography-mass spectrometry analysis of fatty acids profile in herbal medicine. Several critical experimental parameters for MAED, including reaction temperature, microwave power and the amount of derivatization reagent (methanol), were optimized with response surface methodology. The results showed that the chromatographic peak areas of total fatty acids and total unsaturated fatty acids content obtained with MAED were markedly higher than those obtained by the conventional Soxhlet or microwave extraction and then derivatization method. The investigation of kinetics and thermodynamics of the derivatization reaction revealed that microwave assistance could reduce activation energy and increase the Arrhenius pre-exponential factor. The MAED method simplified the sample preparation procedure, shortened the reaction time, but improved the extraction and derivatization efficiency of lipids and reduced ingredient losses, especially for the oxidization and isomerization of unsaturated fatty acids. The simplicity, speed and practicality of this method indicates great potential for high throughput analysis of fatty acids in natural medicinal samples. PMID:22968083

  1. 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

  2. Analysis of phthalate acid esters in environmental water by magnetic graphene solid phase extraction coupled with gas chromatography-mass spectrometry.

    PubMed

    Ye, Qing; Liu, Linhai; Chen, Zhongbao; Hong, Liming

    2014-02-14

    In this work, magnetic graphene composites were synthesized via a simple hydrothermal reaction. The as-prepared composites were successfully applied as an effective adsorbent for the preconcentration of seven phthalate acid esters (PAEs) in environmental water samples prior to gas chromatography-mass spectrometry (GC-MS) analysis. The magnetic graphene composites had a unique structure in which magnetite particles were deposited on graphene sheets. This unique structure not only provided strong magnetic responsiveness for the separation but also prevented the self-aggregation of graphene. The magnetic graphene composites had several advantages, such as large surface area, fast separation ability, and high peak intensity for aromatic analytes; these properties are attributed to the distinct structure of magnetic graphene composites, which comprises p-conjugated networks with a highly exposed surface. Various parameters, including eluting solvent and volume, absorbent amount, extraction time and elution time, were optimized. Validation experiments showed that the optimized method presented good linearity (r>0.997), satisfactory precision (RSD<8.5%), and high recovery (88-110%). The limits of detection were from 0.010μg/L to 0.056μg/L, and the limits of quantification were from 0.035μg/L to 0.19μg/L. The proposed method had these advantages of simplicity, good sensitivity, and high efficiency. Finally, the proposed was successfully applied to the analysis of PAEs in real water samples. PMID:24418236

  3. Analysis of the volatile organic matter of engine piston deposits by direct sample introduction thermal desorption gas chromatography/mass spectrometry.

    PubMed

    Diaby, M; Kinani, S; Genty, C; Bouchonnet, S; Sablier, M; Le Negrate, A; El Fassi, M

    2009-12-01

    This article establishes an alternative method for the characterization of volatiles organic matter (VOM) contained in deposits of the piston first ring grooves of diesel engines using a ChromatoProbe direct sample introduction (DSI) device coupled to gas chromatography/mass spectrometry (GC/MS) analysis. The addition of an organic solvent during thermal desorption leads to an efficient extraction and a good chromatographic separation of extracted products. The method was optimized investigating the effects of several solvents, the volume added to the solid sample, and temperature programming of the ChromatoProbe DSI device. The best results for thermal desorption were found using toluene as an extraction solvent and heating the programmable temperature injector from room temperature to 300 degrees C with a temperature step of 105 degrees C. With the use of the optimized thermal desorption conditions, several components have been positively identified in the volatile fraction of the deposits: aromatics, antioxidants, and antioxidant degradation products. Moreover, this work highlighted the presence of diesel fuel in the VOM of the piston deposits and gave new facts on the absence of the role of diesel fuel in the deposit formation process. Most importantly, it opens the possibility of quickly performing the analysis of deposits with small amounts of samples while having a good separation of the volatiles. PMID:19894696

  4. Development of a simultaneous multiple solid-phase microextraction-single shot-gas chromatography/mass spectrometry method and application to aroma profile analysis of commercial coffee.

    PubMed

    Lee, Changgook; Lee, Younghoon; Lee, Jae-Gon; Buglass, Alan J

    2013-06-21

    A simultaneous multiple solid-phase microextraction-single shot-gas chromatography mass spectrometry (smSPME-ss-GC/MS) method has been developed for headspace analysis. Up to four fibers (50/30 μm DVB/CAR/PDMS) were used simultaneously for the extraction of aroma components from the headspace of a single sample chamber in order to increase sensitivity of aroma extraction. To avoid peak broadening and to maximize resolution, a simple cryofocusing technique was adopted during sequential thermal desorption of multiple SPME fibers prior to a 'single shot' chromatographic run. The method was developed and validated on a model flavor mixture, containing 81 known pure components. With the conditions of 10 min of incubation and 30 min of extraction at 50 °C, single, dual, triple and quadruple SPME extractions were compared. The increase in total peak area with increase in the number of fibers showed good linearity (R(2)=0.9917) and the mean precision was 12.0% (RSD) for the total peak sum, with quadruple simultaneous SPME extraction. Using a real sample such as commercial coffee granules, aroma profile analysis was conducted using single, dual, triple and quadruple SPME fibers. The increase in total peak intensity again showed good linearity with increase in the number of SPME fibers used (R(2)=0.9992) and the precision of quadruple SPME extraction was 9.9% (RSD) for the total peak sum. PMID:23672978

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

    PubMed

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

    2006-11-10

    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 (CIP) was added and mixed with the dried TCM sample, which was used as microwave absorption solid medium for dry distillation of the TCM. At the same time, SPME was used for the extraction and concentration of essential oil after MD. The dry rhizomes of Atractylodes lancea DC was used as the model TCM, and used in the study. The MD-HS-SPME parameters including fiber coating, microwave power, irradiation time, and the amount of added CIP, were studied. To demonstrate the method feasibility, the conventional HS-SPME method was also used for the analysis of essential oil in the TCM. Experimental results show that more compounds were isolated and identified by MD-HS-SPME than those by HS-SPME. Compared to conventional HS-SPME, the advantages of the proposed method are: short extraction time and high extraction efficiency. All experimental results show that the proposed method is an alternative tool for fast analysis of essential oils in dry TCMs. PMID:16950328

  6. Application of an automatic thermal desorption-gas chromatography-mass spectrometry system for the analysis of polycyclic aromatic hydrocarbons in airborne particulate matter.

    PubMed

    Gil-Moltó, J; Varea, M; Galindo, N; Crespo, J

    2009-02-27

    The application of the thermal desorption (TD) method coupled with gas chromatography-mass spectrometry (GC-MS) to the analysis of aerosol organics has been the focus of many studies in recent years. This technique overcomes the main drawbacks of the solvent extraction approach such as the use of large amounts of toxic organic solvents and long and laborious extraction processes. In this work, the application of an automatic TD-GC-MS instrument for the determination of particle-bound polycyclic aromatic hydrocarbons (PAHs) is evaluated. This device offers the advantage of allowing the analysis of either gaseous or particulate organics without any modification. Once the thermal desorption conditions for PAH extraction were optimised, the method was verified on NIST standard reference material (SRM) 1649a urban dust, showing good linearity, reproducibility and accuracy for all target PAHs. The method has been applied to PM10 and PM2.5 samples collected on quartz fibre filters with low volume samplers, demonstrating its capability to quantify PAHs when only a small amount of sample is available. PMID:19150718

  7. Discrimination of Chinese vinegars based on headspace solid-phase microextraction-gas chromatography mass spectrometry of volatile compounds and multivariate analysis.

    PubMed

    Xiao, Zuobing; Dai, Shuiping; Niu, Yunwei; Yu, Haiyan; Zhu, Jiancai; Tian, Huaixiang; Gu, Yongbo

    2011-10-01

    Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography mass spectrometry (GC-MS) was applied for the determination of the characteristic volatile profiles of Chinese vinegars. Multivariate statistical techniques, such as principal component analysis (PCA) and cluster analysis (CA), were used to characterize the different Chinese vinegars by types, fermentation method, and production area. A total of 56 volatile compounds were identified, including 15 esters, 10 aldehydes, 5 acids, 12 alcohols, 5 ketones, 4 volatile phenols, 2 pyrazines, and 3 miscellaneous compounds. The major compounds in Chinese vinegars were furfural, acetic acid, ethyl acetate, 3-hydroxy-2-butanone, 3-methyl-1-butanol, isopentyl acetate, benzaldehyde, phenylethyl alcohol. The PCA results showed that characterizing the Chinese vinegars by HS-SPME-GC-MS was highly related to their type, fermentation method, and production area, and all these influencing factors were not independent. The CA results indicated that the fermentation method had a greater effect than vinegar type and production area. The results showed that HS-SPME-GC-MS together with chemometrics could provide practical reference for characterization of Chinese vinegars. Practical Application:  HS-SPME coupled with GC-MS was applied for the determination of the characteristic volatile profiles of Chinese vinegars. The major compounds in Chinese vinegars were furfural, acetic acid, ethyl acetate, 3-hydroxy-2-butanone, 3-methyl-1-butanol, isopentyl acetate, benzaldehyde, phenylethyl alcohol. HS-SPME-GC-MS together with chemometrics was an efficient tool for evaluating vinegar authenticity. PMID:22417575

  8. Rapid analysis of essential oil from Fructus Amomi by pressurized hot water extraction followed by solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Deng, Chunhui; Wang, Aiqin; Shen, Shun; Fu, Daxi; Chen, Jiakuan; Zhang, Xiangmin

    2005-06-15

    In this paper, a simple, rapid, solvent-free and low-cost method of pressurized hot water extraction (PHWE) followed by headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) was developed for the analysis of essential oil in a traditional Chinese medicine (TCM) of the dried ripe fruit of Fructus Amomi (Sha Ren). The essential oil in the TCM (0.050 g) was extracted by water at 50 bar and 150 degrees C, followed by extraction and concentration by SPME fibers at 80 degrees C for 15min and analysis by GC-MS. The PHWE and HS-SPME parameters were optimized. Thirty-five compounds in the TCM were identified by PHWE-HS-SPME. Among them, camphor, an active compound, in the TCM samples was quantitatively analyzed. The proposed method required little time to prepare the sample. Moreover, little sample mass and no organic solvent was needed. The precision of the present method was found to be good (R.S.D. <10.0%). It is shown that PHWE-SPME-GC-MS is an alternative method for the determination of volatile components in TCMs and can be used as a powerful tool for TCM quality assessment. PMID:15925226

  9. Analysis of host-cell proteins in biotherapeutic proteins by comprehensive online two-dimensional liquid chromatography/mass spectrometry

    PubMed Central

    Xenopoulos, Alex; Fadgen, Keith; Murphy, Jim; Skilton, St. John; Prentice, Holly; Stapels, Martha

    2012-01-01

    Assays for identification and quantification of host-cell proteins (HCPs) in biotherapeutic proteins over 5 orders of magnitude in concentration are presented. The HCP assays consist of two types: HCP identification using comprehensive online two-dimensional liquid chromatography coupled with high resolution mass spectrometry (2D-LC/MS), followed by high-throughput HCP quantification by liquid chromatography, multiple reaction monitoring (LC-MRM). The former is described as a “discovery” assay, the latter as a “monitoring” assay. Purified biotherapeutic proteins (e.g., monoclonal antibodies) were digested with trypsin after reduction and alkylation, and the digests were fractionated using reversed-phase (RP) chromatography at high pH (pH 10) by a step gradient in the first dimension, followed by a high-resolution separation at low pH (pH 2.5) in the second dimension. As peptides eluted from the second dimension, a quadrupole time-of-flight mass spectrometer was used to detect the peptides and their fragments simultaneously by alternating the collision cell energy between a low and an elevated energy (MSE methodology). The MSE data was used to identify and quantify the proteins in the mixture using a proven label-free quantification technique (“Hi3” method). The same data set was mined to subsequently develop target peptides and transitions for monitoring the concentration of selected HCPs on a triple quadrupole mass spectrometer in a high-throughput manner (20 min LC-MRM analysis). This analytical methodology was applied to the identification and quantification of low-abundance HCPs in six samples of PTG1, a recombinant chimeric anti-phosphotyrosine monoclonal antibody (mAb). Thirty three HCPs were identified in total from the PTG1 samples among which 21 HCP isoforms were selected for MRM monitoring. The absolute quantification of three selected HCPs was undertaken on two different LC-MRM platforms after spiking isotopically labeled peptides in the samples. Finally, the MRM quantitation results were compared with TOF-based quantification based on the Hi3 peptides, and the TOF and MRM data sets correlated reasonably well. The results show that the assays provide detailed valuable information to understand the relative contributions of purification schemes to the nature and concentrations of HCP impurities in biopharmaceutical samples, and the assays can be used as generic methods for HCP analysis in the biopharmaceutical industry. PMID:22327428

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

    NASA Astrophysics Data System (ADS)

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

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

  11. Analysis of Glyphosate and Aminomethylphosphonic Acid in Nutritional Ingredients and Milk by Derivatization with Fluorenylmethyloxycarbonyl Chloride and Liquid Chromatography-Mass Spectrometry.

    PubMed

    Ehling, Stefan; Reddy, Todime M

    2015-12-01

    A straightforward analytical method based on derivatization with fluorenylmethyloxycarbonyl chloride and liquid chromatography-mass spectrometry has been developed for the analysis of residues of glyphosate and aminomethylphosphonic acid (AMPA) in a suite of nutritional ingredients derived from soybean, corn, and sugar beet and also in cow's milk and human breast milk. Accuracy and intermediate precision were 91-116% and <10% RSD, respectively, in soy protein isolate. Limits of quantitation were 0.05 and 0.005 μg/g in powdered and liquid samples, respectively. Glyphosate and AMPA were quantified at 0.105 and 0.210 μg/g (soy protein isolate) and 0.850 and 2.71 μg/g (soy protein concentrate, both derived from genetically modified soybean), respectively. Residues were not detected in soy milk, soybean oil, corn oil, maltodextrin, sucrose, cow's milk, whole milk powder, or human breast milk. The method is proposed as a convenient tool for the survey of glyphosate and AMPA in the ingredient supply chain. PMID:26568409

  12. Automated resolution of chromatographic signals by independent component analysis-orthogonal signal deconvolution in comprehensive gas chromatography/mass spectrometry-based metabolomics.

    PubMed

    Domingo-Almenara, Xavier; Perera, Alexandre; Ramírez, Noelia; Brezmes, Jesus

    2016-07-01

    Comprehensive gas chromatography-mass spectrometry (GC×GC-MS) provides a different perspective in metabolomics profiling of samples. However, algorithms for GC×GC-MS data processing are needed in order to automatically process the data and extract the purest information about the compounds appearing in complex biological samples. This study shows the capability of independent component analysis-orthogonal signal deconvolution (ICA-OSD), an algorithm based on blind source separation and distributed in an R package called osd, to extract the spectra of the compounds appearing in GC×GC-MS chromatograms in an automated manner. We studied the performance of ICA-OSD by the quantification of 38 metabolites through a set of 20 Jurkat cell samples analyzed by GC×GC-MS. The quantification by ICA-OSD was compared with a supervised quantification by selective ions, and most of the R(2) coefficients of determination were in good agreement (R(2)>0.90) while up to 24 cases exhibited an excellent linear relation (R(2)>0.95). We concluded that ICA-OSD can be used to resolve co-eluted compounds in GC×GC-MS. PMID:27208528

  13. Analysis of furan in coffee of different provenance by head-space solid phase microextraction gas chromatography-mass spectrometry: effect of brewing procedures.

    PubMed

    La Pera, Lara; Liberatore, Alfredo; Avellone, Giuseppe; Fanara, Serena; Dugo, Giacomo; Agozzino, Pasquale

    2009-06-01

    A simple, sensitive and accurate method for the analysis of furan in roasted coffee has been used based on headspace-solid-phase micro-extraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). The extraction was performed using 75-microm carboxen/polydimethylsiloxane fiber. Ionic strength, extraction time and temperature, and desorption time were assessed as the most important parameters affecting the HS-SPME procedure and d(4)-furan was used as the internal standard. The linearity range was in the range 0.0075-0.486 ng g(-1); the LOD and LOQ calculated using the signal-to-noise ratio approach were 0.002 and 0.006 ng g(-1), respectively. The inter- and intra-day precision was 8 and 10%, respectively. The concentration of furan found in batches of roasted coffee powder different producing countries ranged from 57.3 to 587.3 ng g(-1). The mean reduction in furan levels observed when brewing coffee by either infusion, using a moka pot or an expresso machine was 57, 67.5 and 63.3%, respectively. PMID:19680951

  14. Simultaneous analysis of phthalates, adipate and polycyclic aromatic hydrocarbons in edible oils using isotope dilution-gas chromatography-mass spectrometry.

    PubMed

    Oh, Min-Seok; Lee, Seon-Hwa; Moon, Myeong Hee; Lee, Dong Soo; Park, Hyun-Mee

    2014-01-01

    A method for simultaneous determination of 12 priority phthalates, adipate and polycyclic aromatic hydrocarbons (PAHs) in edible oils by isotope dilution-gas chromatography-mass spectrometry (ID-GC-MS) was developed for fast, accurate and trace analysis. The extraction and clean-up procedures were optimised, and using stable isotope-labelled internal standards for each analyte, relative standard deviations (RSDs) of 0.92-10.6% and spiked sample recoveries of 80.6-97.8% were obtained. Limits of detection for PAHs were in the range of 0.15-0.77 µg/kg and those for phthalates were in the range of 4.6-10.0 µg/kg. The calibration curves exhibited good linearities with regression coefficients of R(2) ≥ 0.99. Twelve edible oils were examined to evaluate the efficiency of this method. Among the 12 analytes, dibutyl phthalates (DBP), diethylhexyl phthalates (DEHP), diethylhexyl adipate (DEHA), benzo[a]anthracene (B[a]A), chrysene (Chry) and benzo[b]fluoranthene (B[b]F) were detected in the range of 1.17-806 µg/kg. PMID:25029399

  15. Analysis of cantharidin in false blister beetles (Coleoptera: Oedemeridae) by headspace solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Mehdinia, Ali; Asiabi, Mina; Jabbari, Ali; Abtahi, S Mohammad

    2011-10-01

    A headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS) method was developed to determine a type of terpenoid named as cantharidin in the false blister beetles, family Oedemeridae. The experimental parameters for HS-SPME method were optimized. Six commercial fibers for HS-SPME method development were tested and the divinylbenzene/carboxene/polydimethylsiloxane fiber was selected to provide the best detection of analyzed compound. The calibration curve showed linearity in the range of 0.1-50 μg mL(-1), correlation coefficient (R(2)=0.992), limit of detection (0.01 ng mL(-1)) and quantitation (0.04 ng mL(-1)) were obtained for the proposed method. The relative standard deviations of intra-day and inter-day assays were 7.8 and 3.4%, respectively. The recovery values, obtained after spiking the beetle samples by three concentration levels of standard solution, were higher than 87%. The results indicated the successful application of the proposed method on the analysis of cantharidin from the false blister beetles. PMID:21907641

  16. Analysis of trace levels of sulfonamide and tetracycline antimicrobials in groundwater and surface water using solid-phase extraction and liquid chromatography/mass spectrometry

    USGS Publications Warehouse

    Lindsey, M.E.; Meyer, M.; Thurman, E.M.

    2001-01-01

    A method has been developed for the trace analysis of two classes of antimicrobials consisting of six sulfonamides (SAs) and five tetracyclines (TCs), which commonly are used for veterinary purposes and agricultural feed additives and are suspected to leach into ground and surface water. The method used solid-phase extraction and liquid chromatography/mass spectrometry (LC/MS) with positive ion electrospray. The unique combination of a metal chelation agent (Na2EDTA) with a macroporous copolymer resulted in quantitative recoveries by solid-phase extraction (mean recovery, 98 ?? 12%) at submicrogram-per-liter concentrations. An ammonium formate/formic acid buffer with a methanol/water gradient was used to separate the antimicrobials and to optimize the signal intensity. Mass spectral fragmentation and ionization characteristics were determined for each class of compounds for unequivocal identification. For all SAs, a characteristic m/z 156 ion representing the sulfanilyl fragment was identified. TCs exhibited neutral losses of 17 amu resulting from the loss of ammonia and 35 amu from the subsequent loss of water. Unusual matrix effects were seen only for TCs in this first survey of groundwater and surface water samples from sites around the United States, requiring that TCs be quantitated using the method of standard additions.

  17. 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

  18. Preparation of Fe3O4@C@PANI magnetic microspheres for the extraction and analysis of phenolic compounds in water samples by gas chromatography-mass spectrometry.

    PubMed

    Meng, Jiaoran; Shi, Chenyi; Wei, Biwen; Yu, Wenjia; Deng, Chunhui; Zhang, Xiangmin

    2011-05-20

    In this work, core-shell structure Fe(3)O(4)@C@polyaniline magnetic microspheres were synthesized using simple hydrothermal reactions. The carbon-coated magnetic microspheres (Fe(3)O(4)@C) were first synthesized by a hydrothermal reaction, and then aniline was polymerized on the magnetic core via another hydrothermal reaction. Then, the obtained Fe(3)O(4)@C@polyaniline magnetic microspheres were applied as magnetic adsorbents for the extraction of aromatic molecules due to π-π interactions between polyaniline shell and aromatic compounds. In our study, five kinds of phenols including phenol, 2,4-dichlorophenol (DCP), 2,4,5-trichlorophenol (TCP), pentachlorophenol (PCP) and bisphenol A (BPA) were selected as the model analytes to verify the extraction ability of Fe(3)O(4)@C@PANI microspheres. After derivatization, the phenols were detected using gas chromatography-mass spectrometry (GC-MS). The dominant parameters affecting enrichment efficiency were investigated and optimized. Under the optimal conditions, the proposed method was evaluated, and applied to the analysis of phenols in real water samples. The results demonstrated that our proposed method based on Fe(3)O(4)@C@polyaniline magnetic microspheres had good linearity (r(2)>0.991), and limits of quantification (2.52-29.7 ng/mL), high repeatability (RSD<13.1%) and good recovery (85.3-110.6%). PMID:21492861

  19. Diagnosis of 21-hydroxylase deficiency by urinary metabolite ratios using gas chromatography-mass spectrometry analysis: Reference values for neonates and infants.

    PubMed

    Kamrath, Clemens; Hartmann, Michaela F; Boettcher, Claudia; Zimmer, Klaus-Peter; Wudy, Stefan A

    2016-02-01

    One major issue of newborn screening programs for 21-hydroxylase deficiency (21OHD) is the high rate of false-positive results, especially in preterm neonates. Urinary steroid metabolite analysis using gas chromatography-mass spectrometry (GC-MS) is suitable as a confirmatory diagnostic tool. The objective of this study was to analyze retrospectively diagnostic metabolite ratios in neonates and infants with and without 21OHD using GC-MS with emphasis on glucocorticoid metabolism, and to develop reference values for the steroid metabolite ratios for the diagnosis of 21OHD. We retrospectively analyzed urinary steroid hormone metabolites determined by GC-MS of 95 untreated neonates and infants with 21OHD (1-148 days), and 261 neonates and infants (100 preterms) without 21OHD (0-217 days). Metabolites of 17α-hydroxyprogesterone showed specificities below 98%, whereas the 21-deoxycortisol metabolite pregnanetriolone clearly separated 21OHD from non-21OHD subjects. The best diagnostic ratio for 21OHD was pregnanetriolone to 6α-hydroxy-tetrahydrocortisone. The lowest value of this ratio in the 21OHD group (0.47) was at least eight times higher than the highest values in the non-21OHD group (0.055). We have given appropriate reference values for steroid metabolite ratios in the largest 21OHD cohort so far described. Consideration of glucocorticoid metabolism, especially the use of typical neonatal 6α-hydroxylates metabolites, leads to improvement of diagnostic metabolite ratios. PMID:26493852

  20. Evaluation of the impact of sulfobutylether7 -β-cyclodextrin on the liquid chromatography-mass spectrometry analysis of biological samples arising from in vivo pharmacokinetic studies.

    PubMed

    Leong, Nathania J; Prankerd, Richard J; Shackleford, David M; Mcintosh, Michelle P

    2015-04-01

    The utility of cyclodextrin (CD) complexation in improving apparent solubility of drugs in parenteral formulations is well established. Administration of these formulations delivers CD directly into the systemic circulation, and it may be necessary to demonstrate unaltered in vivo disposition of a drug coadministered with a CD. Crucial to the undertaking of such a study is the need for bioanalytical assays in which CD presence does not impact drug quantitation. This is of particular importance when assessing the potential impact of in vivo CD complexation on the urinary excretion of a drug, as CDs are predominantly eliminated via glomerular filtration, and hence are present in urine at significantly higher concentration than would be present in blood and plasma. Of 23 publications (in the past 30 years) describing preclinical and clinical assessment of drug pharmacokinetics after i.v. administration of CD-enabled formulations, only two reports clearly stated that the presence of CD had no impact on assay performance. In this work, we describe the simple process involved in (1) predicting the maximum concentrations of a modified CD, sulfobutylether7 -β-CD (SBE7 -β-CD), in plasma and urine samples from preclinical studies, and (2) evaluating the impact of SBE7 -β-CD on the quantitative liquid chromatography-mass spectrometry analysis of rimantadine. PMID:25583633

  1. Analysis of ifosfamide, 4-hydroxyifosfamide, N2-dechloroethylifosfamide, N3-dechloroethylifosfamide and iphosphoramide mustard in plasma by gas chromatography-mass spectrometry.

    PubMed

    Wang, J J; Chan, K K

    1995-12-15

    A sensitive and specific method for the simultaneous quantitation of ifosfamide (IF), 4-hydroxylifosfamide (4-OHIF), N2-dechloroethylifosfamide (N2D), N3-dechloroethylifosfamide (N3D) and iphosphoramide mustard (IPM) has been developed using gas chromatography-mass spectrometry (GC-MS) with an ion-trap mass spectrometer. Deuterium labeled analogues for each of these analytes were synthesized as the internal standards. The labile 4-OHIF in plasma was first converted to the more stable cyanohydrin adducts before dichloromethane extraction. IPM was extracted by C18 reversed-phase resin. All analytes were converted to their silyl derivatives before GC-MS analysis. The sensitivity limits ranged from 0.1 to 0.5 microgram/ml when 100 microliters of plasma was used. This method was validated with within-run coefficients of variation less than 5% (n = 8) and between-run coefficients of variation less than 12% (n = 6). The method was applied to the determination of plasma levels of IF and metabolites in the rat. PMID:8788150

  2. A Statistical Analysis of the Effects of Urease Pre-treatment on the Measurement of the Urinary Metabolome by Gas Chromatography-Mass Spectrometry

    PubMed Central

    Webb-Robertson, Bobbie-Jo; Kim, Young-Mo; Zink, Erika M.; Hallaian, Katherine A.; Zhang, Qibin; Madupu, Ramana; Waters, Katrina M.; Metz, Thomas O.

    2014-01-01

    Urease pre-treatment of urine has been utilized since the early 1960s to remove high levels of urea from samples prior to further processing and analysis by gas chromatography-mass spectrometry (GC-MS). Aside from the obvious depletion or elimination of urea, the effect, if any, of urease pre-treatment on the urinary metabolome has not been studied in detail. Here, we report the results of three separate but related experiments that were designed to assess possible indirect effects of urease pre-treatment on the urinary metabolome as measured by GC-MS. In total, 235 GC-MS analyses were performed and over 106 identified and 200 unidentified metabolites were quantified across the three experiments. The results showed that data from urease pre-treated samples 1) had the same or lower coefficients of variance among reproducibly detected metabolites, 2) more accurately reflected quantitative differences and the expected ratios among different urine volumes, and 3) increased the number of metabolite identifications. Overall, we observed no negative consequences of urease pre-treatment. In contrast, urease pretreatment enhanced the ability to distinguish between volume-based and biological sample types compared to no treatment. Taken together, these results show that urease pretreatment of urine offers multiple beneficial effects that outweigh any artifacts that may be introduced to the data in urinary metabolomics analyses. PMID:25254001

  3. 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 α-pinene, β-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

  4. Traditional sampling with laboratory analysis and solid phase microextraction sampling with field gas chromatography/mass spectrometry by military industrial hygienists.

    PubMed

    Smith, Philip A; Kluchinsky, Timothy A; Savage, Paul B; Erickson, Richard P; Lee, Arthur P; Williams, Kenneth; Stevens, Michael; Thomas, Richard J

    2002-01-01

    The opinions or assertions contained herein are the private ones of the authors and are not to be construed as official or reflecting the views of the United States Department of Defense or the Uniformed Services University of the Health Sciences. Rapid on-site detection and identification of environmental contaminants to which personnel may be exposed is often needed during military deployment situations. The availability of military industrial hygienists with capabilities for "complete" on-site exposure assessment of chemical species should allow detection and identification of a number of important stressors almost immediately following sample collection. Portable gas chromatography/mass spectrometry (GC/MS) provides a rapid and efficient separation of volatile and semivolatile organic analytes, accompanied by sensitive electron impact ionization-mass spectrometry (EI-MS) detection. The use of GC/MS in the field is limited, however, by equipment cost, complexity of the equipment, and the analytical process. Additionally, a skilled operator is needed to obtain useful separations and to interpret mass spectral data. To demonstrate benefits and limitations of "complete" exposure assessment capabilities, a previously unidentified complex mixture, produced by thermal dispersion of riot control agents, was examined. Established active sampling methods were used with laboratory analyses. Solid phase microextraction, a passive sampling method that simplifies preparation for GC/MS analysis, also was used with a field-portable GC/MS system. Both sampling/analysis methods were used to detect CS riot control agent-derived air contaminants dispersed from riot control type canisters through oxidizer-supported combustion of a chemical fuel. PMID:12173177

  5. 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

  6. Analysis of cytochrome P450 metabolites of arachidonic acid by stable isotope probe labeling coupled with ultra high-performance liquid chromatography/mass spectrometry.

    PubMed

    Zhu, Quan-Fei; Hao, Yan-Hong; Liu, Ming-Zhou; Yue, Jiang; Ni, Jian; Yuan, Bi-Feng; Feng, Yu-Qi

    2015-09-01

    Cytochrome P450 metabolites of arachidonic acid (AA) belong to eicosanoids and are potent lipid mediators of inflammation. It is well-known that eicosanoids play an important role in numerous pathophysiological processes. Therefore, quantitative analysis of cytochrome P450 metabolites of AA, including hydroxyeicosatetraenoic acids (HETEs), epoxyeicosatreinoic acids (EETs), and dihydroxyeicosatrienoic acids (DHETs) can provide crucial information to uncover underlying mechanisms of cytochrome P450 metabolites of AA related diseases. Herein, we developed a highly sensitive method to identify and quantify HETEs, EETs, and DHETs in lipid extracts of biological samples based on stable isotope probe labeling coupled with ultra high-performance liquid chromatography/mass spectrometry. To this end, a pair of stable isotope probes, 2-dimethylaminoethylamine (DMED) and d4-2-dimethylaminoethylamine (d4-DMED), were utilized to facilely label eicosanoids. The heavy labeled eicosanoid standards were prepared and used as internal standards for quantification to minimize the matrix and ion suppression effects in mass spectrometry analysis. In addition, the detection sensitivities of DMED labeled eicosanoids improved by 3-104 folds in standard solution and 5-138 folds in serum matrix compared with unlabeled analytes. Moreover, a good separation of eicosanoids isomers was achieved upon DMED labeling. The established method provided substantial sensitivity (limit of quantification at sub-picogram), high specificity, and broad linear dynamics range (3 orders of magnitude). We further quantified cytochrome P450 metabolites of AA in rat liver, heart, brain tissues and human serum using the developed method. The results showed that 19 eicosanoids could be distinctly detected and the contents of 11-, 15-, 16-, 20-HETE, 5,6-EET, and 14,15-EET in type 2 diabetes mellitus patients and 5-, 11-, 12-, 15-, 16-, 20-HETE, 8,9-EET, and 5,6-DHET in myeloid leukemia patients had significant changes, demonstrating that these eicosanoids may have important roles on the pathogenesis of type 2 diabetes mellitus and myeloid leukemia. PMID:26253834

  7. Chemical synthesis of dioxygen-18 labelled omega-/beta-oxidized cysteinyl leukotrienes: analysis by gas chromatography-mass spectrometry and gas chromatography-tandem mass spectrometry.

    PubMed

    Tsikas, D; Fauler, J; Frölich, J C

    1995-05-19

    Cysteinyl leukotrienes (LT) C4, LTD4 and LTE4 are potent mediators of anaphylaxis and inflammation. LTE4 is extensively metabolized in man mainly by omega-oxidation followed by subsequent beta-oxidation to more polar and biologically inactive metabolites. This paper describes a method for the synthesis of [1,20-18O2]-carboxy-LTE4, [1,18-18O2]-carboxy-dinor-LTE4, and [1,16-18O2]-carboxy-14,15-dihydro-tetranor-LTE4 starting from the unlabelled dimethyl esters of 20-carboxy-LTA4, 18-carboxy-dinor-LTA4 and 16-carboxy-14,15-dihydro-tetranor-LTA4, respectively, by separate chemical conjugation with cysteine hydrochloride in H2-18O-methanol followed by alkaline hydrolysis with Li18OH. The isotopic purity of the isolated reaction products was 94% at 18O for all three preparations while only 0.3% remained unlabelled as confirmed by negative-ion chemical-ionization gas chromatography-mass spectrometry (GC-NICI-MS) after their catalytical reduction/desulphurization and derivatization. The 18O2-labelled compounds are demonstrated to be suitable internal standards for quantification by GC-NICI-MS and GC-NICI-tandem MS. We found by GC-NICI-tandem MS that the excretion rate of 20-carboxy-LTE4 is comparable to that of LTE4 (both in nmol/mol creatinine, mean +/- S.E.) in healthy children (26.7 +/- 4.7 vs. 32.0 +/- 6.0, n = 9) and adults (13.9 +/- 1.1 vs. 27.2 +/- 5.4, n = 3). PMID:7663693

  8. Magnetic solid phase extraction and static headspace gas chromatography-mass spectrometry method for the analysis of polycyclic aromatic hydrocarbons.

    PubMed

    Cai, Ying; Yan, Zhihong; Wang, Lijia; NguyenVan, Manh; Cai, Qingyun

    2016-01-15

    A magnetic solid phase extraction (MSPE) protocol combining a static headspace gas chromatography coupled to mass spectrometry (HS-GC-MS) method has been developed for extraction, and determination of 16 polycyclic aromatic hydrocarbons (PAHs) in drinking water samples. Magnetic nanoparticles (MNPs) were coated with 3-aminopropyltriethoxysilane and modified by cholesterol chloroformate. Transmission electron microscope, vibrating sample magnetometer, Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy were used to characterize the cholesterol-functionalized sorbents, and the main parameters affecting the extraction as well as HS sampling, such as sorbent amount, extraction time, oven temperature and equilibration time have been investigated and established. Combination with HS sampling, the MSPE procedure was simple, fast and environmentally friendly, without need of any organic solvent. Method validation proved the feasibility of the developed sorbents for the quantitation of the investigated analytes at trace levels obtaining the limit of detection (S/N=3) ranging from 0.20 to 7.8 ng/L. Good values for intra and inter-day precision were obtained (RSDs ≤ 9.9%). The proposed method was successfully applied to drinking water samples. PMID:26724892

  9. Methods of Analysis - Determination of Pyrethroid Insecticides in Water and Sediment Using Gas Chromatography/Mass Spectrometry

    USGS Publications Warehouse

    Hladik, Michelle L.; Smalling, Kelly L.; Kuivila, Kathryn M.

    2009-01-01

    A method for the determination of 14 pyrethroid insecticides in environmental water and sediment samples is described. The method was developed by the U.S. Geological Survey in response to increasing concern over the effects of pyrethroids on aquatic organisms. The pyrethroids included in this method are ones that are applied to many agricultural and urban areas. Filtered water samples are extracted for pyrethroids using solid-phase extraction (SPE) with no additional cleanup steps. Sediment and soil samples are extracted using a microwave-assisted extraction system, and the pyrethroids of interest are separated from co-extracted matrix interferences by passing the extracts through stacked graphitized carbon and alumina SPE cartridges, along with the use of high-performance liquid chromatography and gel-permeation chromatography (HPLC/GPC). Quantification of the pyrethroids from the extracted water and sediment samples is done using gas chromatography with mass spectrometry (GC/MS) or gas chromatography with tandem mass spectrometry (GC/MS/MS). Recoveries in test water samples fortified at 10 ng/L ranged from 83 to 107 percent, and recoveries in test sediment samples fortified at 10 ug/kg ranged from 82 to 101 percent; relative standard deviations ranged from 5 to 9 percent in the water samples and 3 to 9 percent in the sediment samples. Method detection limits (MDLs), calculated using U.S. Environmental Protection Agency procedures (40 CFR 136, Appendix B), in water ranged from 2.0 to 6.0 ng/L using GC/MS and 0.5 to 1.0 ng/L using GC/MS/MS. For sediment, the MDLs ranged from 1.0 to 2.6 ug/kg dry weight using GC/MS and 0.2 to 0.5 ug/kg dry weight using GC/MS/MS. The matrix-spike recoveries for each compound, when averaged for 12 environmental water samples, ranged from 84 to 96 percent, and when averaged for 27 environmental sediment samples, ranged from 88 to 100 percent.

  10. Field Analysis of Polychlorinated Biphenyls (PCBs) in Soil Using Solid-Phase Microextraction (SPME) and a Portable Gas Chromatography-Mass Spectrometry System.

    PubMed

    Zhang, Mengliang; Kruse, Natalie A; Bowman, Jennifer R; Jackson, Glen P

    2016-05-01

    An expedited field analysis method was developed for the determination of polychlorinated biphenyls (PCBs) in soil matrices using a portable gas chromatography-mass spectrometry (GC-MS) instrument. Soil samples of approximately 0.5 g were measured with a portable scale and PCBs were extracted by headspace solid-phase microextraction (SPME) with a 100 µm polydimethylsiloxane (PDMS) fiber. Two milliliters of 0.2 M potassium permanganate and 0.5 mL of 6 M sulfuric acid solution were added to the soil matrices to facilitate the extraction of PCBs. The extraction was performed for 30 min at 100 ℃ in a portable heating block that was powered by a portable generator. The portable GC-MS instrument took less than 6 min per analysis and ran off an internal battery and helium cylinder. Six commercial PCB mixtures, Aroclor 1016, 1221, 1232, 1242, 1248, 1254, and 1260, could be classified based on the GC chromatograms and mass spectra. The detection limit of this method for Aroclor 1260 in soil matrices is approximately 10 ppm, which is sufficient for guiding remediation efforts in contaminated sites. This method was applicable to the on-site analysis of PCBs with a total analysis time of 37 min per sample. However, the total analysis time could be improved to less than 7 min per sample by conducting the rate-limiting extraction step for different samples in parallel. PMID:27170778

  11. Analysis of urinary metabolic signatures of early hepatocellular carcinoma recurrence after surgical removal using gas chromatography-mass spectrometry.

    PubMed

    Ye, Guozhu; Zhu, Bin; Yao, Zhenzhen; Yin, Peiyuan; Lu, Xin; Kong, Hongwei; Fan, Fei; Jiao, Binghua; Xu, Guowang

    2012-08-01

    The objective of present study was to offer insights into the metabolic responses of hepatocellular carcinoma (HCC) to surgical resection and the metabolic signatures latent in early HCC recurrence (one year after operation). Urinary metabolic profiling employing gas chromatography time-of-flight mass spectrometry (GC-TOF MS) was utilized to investigate the complex physiopathologic regulations in HCC after operational intervention. It was revealed that an intricate series of metabolic regulations including energy metabolism, amino acid metabolism, nucleoside metabolism, tricarboxylic acid (TCA) cycle, gut floral metabolism, etc., principally leading to the direction of biomass synthesis, could be observed after tumor surgical removal. Moreover, metabolic differences between recurrent and nonrecurrent patients had emerged 7 days after initial operation. The metabolic signatures of HCC recurrence principally comprised notable up-regulations of lactate excretion, succinate production, purine and pyrimidine nucleosides turnover, glycine, serine and threonine metabolism, aromatic amino acid turnover, cysteine and methionine metabolism, and glyoxylate metabolism, similar to metabolic behaviors of HCC burden. Sixteen metabolites were found to be significantly increased in the recurrent patients compared with those in nonrecurrent patients and healthy controls. Five metabolites (ethanolamine, lactic acid, acotinic acid, phenylalanine and ribose) were further defined; they were favorable to the prediction of early recurrence. PMID:22768978

  12. Commonly Practiced Quality Control and Quality Assurance Procedures for Gas Chromatography-Mass Spectrometry Analysis in Forensic Urine Drug-Testing Laboratories.

    PubMed

    Goldberger, B A; Huestis, M A; Wilkins, D G

    1997-12-01

    Forensic urine drug-testing laboratories operate in a prescribed scientific and administrative manner to ensure accurate test results. All specimens positive by an initial immunoassay test must be confirmed by gas chromatography/mass spectrometry (GC/MS). To provide adequate control and verification of these analytical processes, laboratories must implement appropriate policies and procedures to be used in routine practice. This review describes the following topics regarding GC/MS analyses: method validation, instrument performance, assay calibration, quality control, criteria for designating a positive test result, sample and batch acceptance criteria, and GC/MS data review. PMID:26269941

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

    USGS Publications Warehouse

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

    1977-01-01

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

  14. 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

  15. 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…

  16. Precolumn sample-enrichment device for analysis of ambient volatile organics by gas chromatography-mass spectrometry

    SciTech Connect

    Arnts, R.R.

    1985-01-01

    Gas chromatographic-mass spectrometric (GC/MS) identification of air pollutants generally requires a preconcentration step to provide sufficient sample for analysis. Cryogenic trapping is often used to enrich the sample since nitrogen and oxygen are not condensed. It does, however, concentrate enormous quantities of water and carbon dioxide - enough to plug high-resolution narrow-bore capillary columns needed for separation of complex environmental samples. Whole-air samples were collected in stainless steel containers or Tedlar bags for analysis by gas chromatography with flame ionization detection (GC/FID). In order to provide identification of unknown peaks and confirmation of tentatively named peaks, the system described herein was designed and built to enrich samples for GC/MS analysis of volatile organics. The preconcentration system consists of a solid sorbent trap and a cryogenic trap used in sequence to collect organic vapors and focus them for analysis by GC/MS.

  17. Analysis of trace contamination of phthalate esters in ultrapure water using a modified solid-phase extraction procedure and automated thermal desorption-gas chromatography/mass spectrometry.

    PubMed

    Liu, Hsu-Chuan; Den, Walter; Chan, Shu-Fei; Kin, Kuan Tzu

    2008-04-25

    The present study was aimed to develop a procedure modified from the conventional solid-phase extraction (SPE) method for the analysis of trace concentration of phthalate esters in industrial ultrapure water (UPW). The proposed procedure allows UPW sample to be drawn through a sampling tube containing hydrophobic sorbent (Tenax TA) to concentrate the aqueous phthalate esters. The solid trap was then demoisturized by two-stage gas drying before subjecting to thermal desorption and analysis by gas chromatography-mass spectrometry. This process removes the solvent extraction procedure necessary for the conventional SPE method, and permits automation of the analytical procedure for high-volume analyses. Several important parameters, including desorption temperature and duration, packing quantity and demoisturizing procedure, were optimized in this study based on the analytical sensitivity for a standard mixture containing five different phthalate esters. The method detection limits for the five phthalate esters were between 36 ng l(-1) and 95 ng l(-1) and recovery rates between 15% and 101%. Dioctyl phthalate (DOP) was not recovered adequately because the compound was both poorly adsorbed and desorbed on and off Tenax TA sorbents. Furthermore, analyses of material leaching from poly(vinyl chloride) (PVC) tubes as well as the actual water samples showed that di-n-butyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP) were the common contaminants detected from PVC contaminated UPW and the actual UPW, as well as in tap water. The reduction of DEHP in the production processes of actual UPW was clearly observed, however a DEHP concentration of 0.20 microg l(-1) at the point of use was still being quantified, suggesting that the contamination of phthalate esters could present a barrier to the future cleanliness requirement of UPW. The work demonstrated that the proposed modified SPE procedure provided an effective method for rapid analysis and contamination identification in UPW production lines. PMID:18342867

  18. 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

  19. Beta2-adrenergic agonist residues: simultaneous methyl- and butylboronic derivatization for confirmatory analysis by gas chromatography-mass spectrometry.

    PubMed

    Ramos, F; Santos, C; Silva, A; da Silveira, M I

    1998-09-25

    A derivatization procedure for confirmatory residue analysis of beta2-agonists is described. Methyl (MBA) and butyl (BBA) boronic acids are simultaneously used for the derivatization of tulobuterol, mabuterol, mapenterol, salbutamol, clenproperol, clenbuterol, clenpenterol and bromobuterol by GC-MS determination. A temperature of 55 degrees C during 60 min was selected as optimal temperature-time condition for simultaneous MBA and BBA beta2-agonists derivatization. It was also observed that stability of boronic derivatives was maintained at -20 degrees C over a period of four days. The proposed methodology was tested in urine and it could be applied for confirmatory residue analysis of clenbuterol-like compounds. PMID:9824253

  20. 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.

  1. 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

  2. Quantitative analysis of fragrance in selectable one dimensional or two dimensional gas chromatography-mass spectrometry with simultaneous detection of multiple detectors in single injection.

    PubMed

    Tan, Hui Peng; Wan, Tow Shi; Min, Christina Liew Shu; Osborne, Murray; Ng, Khim Hui

    2014-03-14

    A selectable one-dimensional ((1)D) or two-dimensional ((2)D) gas chromatography-mass spectrometry (GC-MS) system coupled with flame ionization detector (FID) and olfactory detection port (ODP) was employed in this study to analyze perfume oil and fragrance in shower gel. A split/splitless (SSL) injector and a programmable temperature vaporization (PTV) injector are connected via a 2-way splitter of capillary flow technology (CFT) in this selectable (1)D/(2)D GC-MS/FID/ODP system to facilitate liquid sample injections and thermal desorption (TD) for stir bar sorptive extraction (SBSE) technique, respectively. The dual-linked injectors set-up enable the use of two different injector ports (one at a time) in single sequence run without having to relocate the (1)D capillary column from one inlet to another. Target analytes were separated in (1)D GC-MS/FID/ODP and followed by further separation of co-elution mixture from (1)D in (2)D GC-MS/FID/ODP in single injection without any instrumental reconfiguration. A (1)D/(2)D quantitative analysis method was developed and validated for its repeatability - tR; calculated linear retention indices (LRI); response ratio in both MS and FID signal, limit of detection (LOD), limit of quantitation (LOQ), as well as linearity over a concentration range. The method was successfully applied in quantitative analysis of perfume solution at different concentration level (RSD≤0.01%, n=5) and shower gel spiked with perfume at different dosages (RSD≤0.04%, n=5) with good recovery (96-103% for SSL injection; 94-107% for stir bar sorptive extraction-thermal desorption (SBSE-TD). PMID:24548435

  3. A gas chromatography-mass spectrometry multi-target method for the simultaneous analysis of three classes of metabolites in marine organisms.

    PubMed

    Pereira, David M; Vinholes, Juliana; de Pinho, Paula Guedes; Valentão, Patrícia; Mouga, Teresa; Teixeira, Natércia; Andrade, Paula B

    2012-10-15

    In this work a fast and simple multi-target gas chromatography-mass spectrometry (GC-MS) method for the simultaneous detection and absolute quantification of amino acids, fatty acids, sterols and lupanes in marine organisms is proposed. The methodology was applied to the characterization of the echinoderm Marthasterias glacialis Linnaeus spiny sea star extracts. The main factors influencing the extraction of target compounds were evaluated by using different extraction procedures, solvent systems and temperature conditions and a comparison with a reference technique was performed. The most suitable procedure, capable of successfully extract the three classes of target compounds, was ethanol as solvent at 40°C under magnetic stirring. Good analytical parameters were obtained since calibrations curves for the 40 compounds under analysis (15 amino acids, 16 fatty acids, 6 sterols and 3 lupanes) showed regression coefficients (r(2)) ranging from 0.9844 to 0.9978, with low RSD (from 0.00 to 9.45%), and detection limits varying from 0.03 to 15.40 μg/L. The RSD values for intra- and interday variations studies were also good (RSD<13.5%, for both) and recoveries were higher than 92%. Variation in samples from different harvests and origins and their chemical composition during the year is reported. The fact that no previous treatment of samples is required can make this a useful technique for metabolite profiling in marine organisms, among others, both in biomedical and nutritional studies. Moreover, due to the fast and robust character of the proposed method it seems to be suitable for the implementation as routine analysis. PMID:23141354

  4. Environmentally friendly analysis of emerging contaminants by pressurized hot water extraction-stir bar sorptive extraction-derivatization and gas chromatography-mass spectrometry.

    PubMed

    Pintado-Herrera, Marina G; González-Mazo, Eduardo; Lara-Martín, Pablo A

    2013-01-01

    This work describes the development, optimization, and validation of a new method for the simultaneous determination of a wide range of pharmaceuticals (beta-blockers, lipid regulators…) and personal care products (fragrances, UV filters, phthalates…) in both aqueous and solid environmental matrices. Target compounds were extracted from sediments using pressurized hot water extraction followed by stir bar sorptive extraction. The first stage was performed at 1,500 psi during three static extraction cycles of 5 min each after optimizing the extraction temperature (50-150 °C) and addition of organic modifiers (% methanol) to water, the extraction solvent. Next, aqueous extracts and water samples were processed using polydimethylsiloxane bars. Several parameters were optimized for this technique, including extraction and desorption time, ionic strength, presence of organic modifiers, and pH. Finally, analytes were extracted from the bars by ultrasonic irradiation using a reduced amount of solvent (0.2 mL) prior to derivatization and gas chromatography-mass spectrometry analysis. The optimized protocol uses minimal amounts of organic solvents (<10 mL/sample) and time (≈8 h/sample) compared to previous existing methodologies. Low standard deviation (usually below 10%) and limits of detection (sub-ppb) vouch for the applicability of the methodology for the analysis of target compounds at trace levels. Once developed, the method was applied to determine concentrations of these compounds in several types of sample (wastewater, seawater, pore water, and sediment) from Cadiz Bay (SW Spain). To our knowledge, these findings represent the first information available on the presence of some of the target compounds in the marine environment. PMID:23064672

  5. 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

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

    PubMed Central

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

    2014-01-01

    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 (R2>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

  7. Simultaneous analysis of amphetamine-type stimulants in plasma by solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Mariotti, Kristiane de Cássia; Schuh, Roselena S; Ferranti, Priscila; Ortiz, Rafael S; Souza, Daniele Z; Pechansky, Flavio; Froehlich, Pedro E; Limberger, Renata P

    2014-09-01

    Brazil is considered one of the countries with the highest number of amphetamine-type stimulant (ATS) users worldwide, mainly diethylpropion (DIE) and fenproporex (FEN). The use of ATS is mostly linked to diverted prescription stimulants and this misuse is widely associated with (ab)use by drivers. A validated method was developed for the simultaneous analysis of amphetamine (AMP), DIE and FEN in plasma samples employing direct immersion-solid-phase microextraction, and gas chromatographic/mass spectrometric analysis. Trichloroacetic acid 10% was used for plasma deproteinization. In situ derivatization with propylchloroformate was employed. The linear range of the method covered from 5.0 to 100 ng/mL. The detection limits were 1.0 (AMP), 1.5 (DIE) and 2.0 ng/mL (FEN). The accuracy assessment of the control samples was within 85.58-108.33% of the target plasma concentrations. Recoveries ranged from 46.35 to 84.46% and precision was <15% of the value of relative standard deviation. This method is appropriate for screening and confirmation in plasma forensic toxicology analyses of these basic drugs. PMID:25038769

  8. Imidacloprid Extraction from Citrus Leaves and Analysis by Liquid Chromatography-Mass Spectrometry (HPLC-MS/MS).

    PubMed

    Leiva, Jorge A; Nkedi-Kizza, Peter; Borejsza-Wysocki, Wlodzimierz S; Bauder, Victor S; Morgan, Kelly T

    2016-05-01

    A procedure was developed to extract Imidacloprid (IMD) from newly-flushed and fully-expanded citrus leaves. The extraction was conducted in a bullet blender, using a small sample mass (0.5 g of fresh tissue), stainless-steel beads (24 g), and methanol as extractant (10 mL). The extracts did not require further clean-up before analysis by HPLC-MS/MS. The method was validated with control samples from IMD-untreated Hamlin orange trees. The method limit of detection and limit of quantitation were 0.04 and 0.12 μg g(-1), respectively. IMD recoveries from fortified leaf tissue were between 92 % and 102 %, with relative standard deviations of <8 %. The method was further evaluated by extracting leaves from Hamlin orange trees treated with IMD. The treated trees showed maximum concentrations of 10.8 and 21.8 µg g(-1), observed at 20 days after applying two soil-drenching rates (0.51 and 1.02 kg IMD ha(-1)), respectively. This extraction technique will generate useful data on IMD plant uptake, foliar concentration, and correlations with Asian citrus psyllid (ACP) mortality or control. The method could be used to generate baseline data to improve IMD soil-drenching applications as the main management practice to control the ACP. PMID:26988226

  9. 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. PMID:25701418

  10. Optimization of the derivatization protocol of pentacyclic triterpenes prior to their gas chromatography-mass spectrometry analysis in plant extracts.

    PubMed

    Jemmali, Zaineb; Chartier, Agnes; Dufresne, Christelle; Elfakir, Claire

    2016-01-15

    This paper focuses on the application of a two-level full factorial design to optimize the key derivatization step before the GC-FID and GC-MS analysis of pentacyclic triterpenes. The derivatization reaction was screened for influential factors and statistically significant parameters with a p value less than 0.05. A multi-response optimization based on a desirability function was then applied, while simultaneously considering overall detection enhancement of compounds. Results showed that derivatization using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and trimethylchlorosilane (TMCS) in pyridine (22:13:65v/v/v) for 2h at 30°C was the most efficient method of derivatizing all the hydroxyl and carboxylic acid groups contained in the triterpene structures. The validity of the method was demonstrated using GC-MS analyzes of a mixture containing eleven standards (β-amyrin, α-amyrin, lupeol, erythrodiol, uvaol, betulin, oleanolic acid, betulinic acid, ursolic acid, maslinic acid and corosolic acid). These compounds are representative of different classes of terpene compounds bearing different functional groups such as alcohols, diols, and carboxylic acids. The derivatization procedure was then tested on four plant extracts: apple pomace, salvia sclarea (dried leaves and flowers), sea buckthorn (Hyppophae rhammnoides L.) berries, and B. serrata resin. The identification of triterpenes was based on the comparison of their retention time and mass spectra to those of standards. The presence of compounds already identified in the literature was confirmed and new ones such as maslinic and corosolic acids were identified in apples, sea buckthorn and salvia sclarea. PMID:26592573

  11. Analysis of vinylidene chloride and 1-chlorobutane in foods packaged with polyvinylidene chloride casing films by headspace gas chromatography/mass spectrometry (GC/MS).

    PubMed

    Ohno, H; Kawamura, Y

    2006-08-01

    A headspace gas chromatography/mass spectrometry method was developed for the simultaneous determination of vinylidene chloride and 1-chlorobutane in foods packaged with polyvinylidene chloride casing films. The solid foodstuff was homogenized with an equal mass of distilled water. The homogenate was incubated for 1 h at 90 degrees C in a sealed headspace vial, and the headspace gas was then analysed by gas chromatography/mass spectrometry in selected ion-monitoring mode using a bonded porous polymer-coated capillary column. The recovery rates of vinylidene chloride and 1-chlorobutane in foodstuffs were 94.5-103.9 and 85.8-120.3%, respectively. Among 13 samples tested, vinylidene chloride was detected at 0.001-0.020 microg g(-1) in 11 foodstuffs, and 1-chlorobutane was detected at 0.004-0.040 microg g(-1) in all 13 foodstuffs. Furthermore, vinylidene chloride was detected at 0.04 microg g(-1) in one casing film, and 1-chlorobutane was detected in all casing films. The results indicate that these compounds migrated from the casing films into the foodstuffs. PMID:16807210

  12. The Mars Organic Molecule Analyser : in situ analysis of organic compounds on Mars by Gas Chromatography-Mass Spectrometry.

    NASA Astrophysics Data System (ADS)

    Buch, Arnaud; Sternberg, Robert; Freissinet, Caroline; Pinnick, Veronika; Szopa, Cyril; Coll, Patrice; Geffroy-Rodier, Claude; Raulin, Francois; Goesmann, Fred

    The search for signs of past or present life is one of the primary goals of the future Mars exploratory missions. With this aim the Mars Organic Molecule Analyzer (MOMA) experiment of the ExoMars 2016-2018 next coming joint ESA/NASA mission is designed to perform the in situ analysis of exobiological organic molecules of exobiological interest in the Martian soil such as amino acids, carboxylic acids, nucleobases or polycyclic aromatic hydrocarbons (PAHs). With the aim to separate and detect organic compounds from Martian soil, US and European teams have respectively built an ion trap mass spectrometer and a gas chromatograph. The mass spectrometer prototype has been coupled with the gas chromatograph prototype which is able to work in standalone mode by using a TCD detector. A GC-MS compatible sample processing system (SPS) allowing the extraction and the chemical transformation of the organic compounds from the soil, within space compatible operating conditions, has also been devel-oped. The sample processing is performed in an oven, dedicated to the MOMA experiment containing the solid sample (50-100mg). The internal temperature of which can be ranged from 20 to 1000 C. The extraction step is achieved by using thermodesorption in the range of 100 to 300C for 5 to 20 min. Then, the chemical derivatization and/or thermochemolysis of the extracted compounds is performed directly on the soil with a mixture of MTBSTFA-DMF, TMAH or DMF-DMA solution when enantiomeric separation is required. By decreasing the polarity of the target molecules, this step allows their volatilization at a temperature below 250C without any chemical degradation. Once derivatized, the volatile target molecules are trapped in a cold and chemical trap and promptly desorbed into the gas chromatograph coupled with a mass spectrometer. Preliminary tests, performed on Martian analogue soils (Atacama), with the MOMA SPS-GC/MS experiment, allowed the detection of organic compounds such as amino and carboxylic acids below the ppm level.

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

    PubMed

    Schtt, Hans-Frieder; Ltjohann, 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

  14. A urinary metabonomics analysis of long-term effect of acetochlor exposure on rats by ultra-performance liquid chromatography/mass spectrometry.

    PubMed

    Li, Longxue; Wang, Maoqing; Chen, Shuhong; Zhao, Wei; Zhao, Yue; Wang, Xu; Zhang, Yang

    2016-03-01

    The study was to assess the long-term toxic effects of acetochlor on rats. Two different doses (42.96 and 107.4mg/kgbodyweight/day) of acetochlor were administered to Wistar rats through their food for over 24weeks. Rat urine samples were collected at two time-points for the measurements of the metabonomics profiles with ultra-performance liquid chromatography-mass spectrometry (UPLC-MSMS). The results of clinical chemistry and histopathology suggested that long-term use of acetochlor in rats caused liver and kidney damage, and dysfunction of antioxidant system. The urinary metabonomics analysis indicated that the high and low-dose exposure of acetochlor could cause alterations of these metabonomics in urine in the rat. Significant changes of the levels of hippuric acid (0.403-fold decrease), citric acid (0.430-fold decrease), pantothenic acid (0.486-fold decrease), uracil (0.419-fold decrease), β-Alanine (0.325-fold decrease), nonanedioic acid (0.445-fold decrease), l-tyrosine (0.410-fold decrease), d-glucuronic acid (8.389-fold increase) and 2-ethyl-6-methyl-N-methyl-2-chloro-acetanilide in urine were observed. In addition, it may interfere with the fatty acid synthesis, the pyrimidine degradation and pantothenate biosynthesis. The level of 2-ethyl-6-methyl-N-methyl-2-chloro-acetanilide is detected in all treated groups which is not found in the control groups, indicating which can be used as an early, sensitive marker of acetochlor exposure in rat. This study illustrates the important utility of metabonomics approaches to understand the toxicity of long-term exposure of acetochlor. PMID:26969444

  15. Global urinary metabolic profiling procedures using gas chromatography-mass spectrometry.

    PubMed

    Chan, Eric Chun Yong; Pasikanti, Kishore Kumar; Nicholson, Jeremy K

    2011-10-01

    The role of urinary metabolic profiling in systems biology research is expanding. This is because of the use of this technology for clinical diagnostic and mechanistic studies and for the development of new personalized health care and molecular epidemiology (population) studies. The methodologies commonly used for metabolic profiling are NMR spectroscopy, liquid chromatography mass spectrometry (LC/MS) and gas chromatography-mass spectrometry (GC/MS). In this protocol, we describe urine collection and storage, GC/MS and data preprocessing methods, chemometric data analysis and urinary marker metabolite identification. Results obtained using GC/MS are complementary to NMR and LC/MS. Sample preparation for GC/MS analysis involves the depletion of urea via treatment with urease, protein precipitation with methanol, and trimethylsilyl derivatization. The protocol described here facilitates the metabolic profiling of ∼400-600 metabolites in 120 urine samples per week. PMID:21959233

  16. Comprehensive Urine Drug Screen by Gas Chromatography/Mass Spectrometry (GC/MS).

    PubMed

    Ramoo, Bheemraj; Funke, Melissa; Frazee, Clint; Garg, Uttam

    2016-01-01

    Drug screening is an essential component of clinical toxicology laboratory service. Some laboratories use only automated chemistry analyzers for limited screening of drugs of abuse and few other drugs. Other laboratories use a combination of various techniques such as immunoassays, colorimetric tests, and mass spectrometry to provide more detailed comprehensive drug screening. Mass spectrometry, gas or liquid, can screen for hundreds of drugs and is often considered the gold standard for comprehensive drug screening. We describe an efficient and rapid gas chromatography/mass spectrometry (GC/MS) method for comprehensive drug screening in urine which utilizes a liquid-liquid extraction, sample concentration, and analysis by GC/MS. PMID:26660182

  17. 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.

  18. Direct chemical-analysis of uv laser-ablation products of organic polymers by using selective ion monitoring mode in gas-chromatography mass-spectrometry

    USGS Publications Warehouse

    Cho, Yirang; Lee, H.W.; Fountain, S.T.; Lubman, D.M.

    1994-01-01

    Trace quantities of laser ablated organic polymers were analyzed by using commercial capillary column gas chromatography/mass spectrometry; the instrument was modified so that the laser ablation products could be introduced into the capillary column directly and the constituents of each peak in the chromatogram were identified by using a mass spectrometer. The present study takes advantage of the selective ion monitoring mode for significantly improving the sensitivity of the mass spectrometer as a detector, which is critical in analyzing the trace quantities and confirming the presence or absence of the species of interest in laser ablated polymers. The initial composition of the laser ablated polymers was obtained by using an electron impact reflectron time-of-flight mass spectrometer and the possible structure of the fragments observed in the spectra was proposed based on the structure of the polymers.

  19. Use of headspace sorptive extraction coupled to gas chromatography-mass spectrometry for the analysis of volatile polycyclic aromatic hydrocarbons in herbal infusions.

    PubMed

    Cacho, J I; Campillo, N; Viñas, P; Hernández-Córdoba, M

    2014-08-22

    A solvent-free method is described for the determination of 10 volatile polycyclic aromatic hydrocarbons (PAHs), considered as priority pollutants by the EU, in different herbal infusions using headspace sorptive extraction (HSSE) and gas chromatography-mass spectrometry (GC-MS). The parameters affecting both the extraction and thermal desorption steps in the HSSE were optimized by means of Plackett-Burman designs. Ten millilitres of the herbal infusion was submitted to the HSSE preconcentration in the presence of salt for 4h at 88 °C. The use of d(10)-phenanthrene as internal standard not only improved the repeatability of the method but allowed quantification of the samples against external aqueous standards. Detection limits ranged between 11 and 26 ng L(-1). PMID:25001331

  20. Analysis of t-butylphenol acetylene condensed resin with methyl-methine linkages in vulcanized rubber by pyrolysis-gas chromatography/mass spectrometry

    PubMed

    Kim; Lee

    1999-01-01

    Methyl-methine linkages of Novolac, a commercially available t-butylphenol acetylene condensed (TBPA) resin, have been identified by recognition of pyrolysis pathways using pyrolysis-gas chromatography/mass spectrometry (Py-GC/mS) in vulcanized rubber. The diagnostic mass spectrum of t-butylphenol with methyl-methine linkages between phenolic rings was observed at m/z 192, corresponding to 4-t-butyl-2-ethyl-6-methylphenol. Other molecular ions were observed at m/z 178, 164, and 150 in the characteristic pyrolyzates. The ion at m/z 192 in the TBPA resin was observed to be characteristic for methyl-methine linkages between the phenolic groups, and the analytical pyrolysis-GC/mS method was thus able to identify the resin at low levels in vulcanized rubber. Copyright 1999 John Wiley & Sons, Ltd. PMID:10482900

  1. Analysis of chemical warfare agents in organic liquid samples with magnetic dispersive solid phase extraction and gas chromatography mass spectrometry for verification of the chemical weapons convention.

    PubMed

    Singh, Varoon; Purohit, Ajay Kumar; Chinthakindi, Sridhar; Goud, Raghavender D; Tak, Vijay; Pardasani, Deepak; Shrivastava, Anchal Roy; Dubey, Devendra Kumar

    2016-05-27

    A simple, sensitive and low temperature sample preparation method is developed for detection and identification of Chemical Warfare Agents (CWAs) and scheduled esters in organic liquid using magnetic dispersive solid phase extraction (MDSPE) followed by gas chromatography-mass spectrometry analysis. The method utilizes Iron oxide@Poly(methacrylic acid-co-ethylene glycol dimethacrylate) resin (Fe2O3@Poly(MAA-co-EGDMA)) as sorbent. Variants of these sorbents were prepared by precipitation polymerization of methacrylic acid-co-ethylene glycol dimethacrylate (MAA-co-EGDMA) onto Fe2O3 nanoparticles. Fe2O3@poly(MAA-co-EGDMA) with 20% MAA showed highest recovery of analytes. Extractions were performed with magnetic microspheres by MDSPE. Parameters affecting the extraction efficiency were studied and optimized. Under the optimized conditions, method showed linearity in the range of 0.1-3.0μgmL(-1) (r(2)=0.9966-0.9987). The repeatability and reproducibility (relative standard deviations (RSDs) %) were in the range of 4.5-7.6% and 3.4-6.2% respectively for organophosphorous esters in dodecane. Limits of detection (S/N=3/1) and limit of quantification (S/N=10/1) were found to be in the range of 0.05-0.1μgmL(-1) and 0.1-0.12μgmL(-1) respectively in SIM mode for selected analytes. The method was successfully validated and applied to the extraction and identification of targeted analytes from three different organic liquids i.e. n-hexane, dodecane and silicon oil. Recoveries ranged from 58.7 to 97.3% and 53.8 to 95.5% at 3μgmL(-1) and 1μgmL(-1) spiking concentrations. Detection of diethyl methylphosphonate (DEMP) and O-Ethyl S-2-diisopropylaminoethyl methylphosphonothiolate (VX) in samples provided by the Organization for Prohibition of Chemical Weapons Proficiency Test (OPCW-PT) proved the utility of the developed method for the off-site analysis of CWC relevant chemicals. PMID:27113675

  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. Gas chromatography-mass spectrometry of biofluids and extracts.

    PubMed

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

    2015-01-01

    Gas chromatography-mass spectrometry (GC-MS) has been widely used in metabonomics analyses of biofluid samples. Biofluids provide a wealth of information about the metabolism of the whole body and from multiple regions of the body that can be used to study general health status and organ function. Blood serum and blood plasma, for example, can provide a comprehensive picture of the whole body, while urine can be used to monitor the function of the kidneys, and cerebrospinal fluid (CSF) will provide information about the status of the brain and central nervous system (CNS). Different methods have been developed for the extraction of metabolites from biofluids, these ranging from solvent extracts, acids, heat denaturation, and filtration. These methods vary widely in terms of efficiency of protein removal and in the number of metabolites extracted. Consequently, for all biofluid-based metabonomics studies, it is vital to optimize and standardize all steps of sample preparation, including initial extraction of metabolites. In this chapter, recommendations are made of the optimum experimental conditions for biofluid samples for GC-MS, with a particular focus on blood serum and plasma samples. PMID:25677149

  4. Mercury determination in blood by gas chromatography-mass spectrometry.

    PubMed

    Aggarwal, S K; Kinter, M; Herold, D A

    1994-01-01

    A stable isotope dilution gas chromatography-mass spectrometry method using 196Hg as an internal standard is described for determining Hg in blood. In this method, the blood samples are not subjected to any digestion to avoid the loss of Hg. A solution of 0.6M HCl is used to free Hg present in blood from proteins. The pH of the solution is adjusted to 9 using borate buffer and Hg chelated using lithium bis(trifluoroethyl)dithiocarbamate. All isotope ratio measurements are made using an organic mass spectrometer. Overall precision values for the five major Hg isotopes relative to 202Hg are 1.6-2.3% when 10 ng samples of chelated Hg are analyzed. No appreciable memory or carryover effect is observed when two synthetic mixtures differing in 196Hg/202Hg ratios by a factor of 30 are sequentially analyzed. The method is validated by determining Hg in blood samples using isotope dilution GC-MS. PMID:7946912

  5. Application of fast atom bombardment with tandem mass spectrometry and liquid chromatography/mass spectrometry to the analysis of acylcarnitines in human urine, blood, and tissue

    SciTech Connect

    Millington, D.S.; Norwood, D.L.; Kodo, N.; Roe, C.R.; Inoue, F. )

    1989-08-01

    Using a precursor-ion scan function on a triple quadrupole mass spectrometer, acylcarnitines were detected in the target matrices at or below concentrations of 1 nmol per gram by fast atom bombardment mass spectrometry. Acylcarnitine profiles from patients with known metabolic disorders were consistent with previously acquired data. Putative acylcarnitine signals were confirmed in one case by administration of stable isotope-labeled carnitine, which equilibrated rapidly with the endogenous pool. The addition of a continuous flow system enabled rapid sequential analysis without operator intervention, indicating the potential for automation of the analytical procedure. Incorporation of a micro-LC column enabled on-line liquid chromatographic/mass spectrometric analysis of selected patient samples. Large-scale screening and quantitative analysis of urine or blood for diagnostic acylcarnitines are now practicable.

  6. Characterisation of beeswax in works of art by gas chromatography-mass spectrometry and pyrolysis-gas chromatography-mass spectrometry procedures.

    PubMed

    Bonaduce, Ilaria; Colombini, Maria Perla

    2004-03-01

    Pyrolysis (Py) with in situ derivatisation with hexamethyldisilazane-gas chroma-break tography-mass spectrometry (GC-MS) and a gas chromatography-mass spectrometry procedure based on microwave-assisted saponification were used to identify the organic components in small sized beeswax samples. With the latter procedure quantitative recoveries can be made and hydrocarbons, alcohols and omega-1-diols in the neutral fraction, and fatty acids and omega-1-hydroxy acids in the acidic fraction can be efficiently separated and detected. Both procedures were used to characterise a wax anatomic sculpture "The Plague" (1691-1694) by Gaetano Zumbo, resulting in the identification of beeswax and a Pinaceae resin. The GC-MS analysis brought to light some essential differences in beeswax composition between the raw material and the old modelled wax thus giving some clear indications about the recipe used by the sculptor. PMID:14989483

  7. Simple method for the analysis of glycerol enol ethers derived from plasmalogens in complex lipid mixtures and subsequent determination of the aldehydic components by gas chromatography-mass spectrometry.

    PubMed

    Knörr, W; Spiteller, G

    1990-04-01

    Glycerol enol ethers, obtained by the reduction of plasmalogens with lithium aluminum hydride, can be converted into glycerol alk-(1)-enyl ether bismethyl ethers with diazomethane in the presence of silica gel. Their mass spectra allow the position of the enol ether group in glycerol unit to be deduced. Branches in the aldehydic components of the glycerol alk-(1)-enyl ether bismethyl ethers can be identified unequivocally by preparation of the 2-alkyl-1,3-dithiolanes, desulphurization with Raney nickel and deuterium to hydrocarbons and subsequent analysis by gas chromatography-mass spectrometry. PMID:2361975

  8. Characterization and quantitative amino acids analysis of analgesic peptides in cinobufacini injection by size exclusion chromatography, matrix-assisted laser desorption/ionization time of flight mass spectrometry and gas chromatography mass spectrometry.

    PubMed

    Wu, Xu; Si, Nan; Bo, Gao; Hu, Hao; Yang, Jian; Bian, Baolin; Zhao, Hai Yu; Wang, Hongjie

    2015-01-01

    Cinobufacini injection that comes from the water extract of Bufo bufo gargarizans Cantor skin is widely used for cancer treatment in China. Peptide is one of its major types of constituents, however the biological effects and content of this injection are little reported. In present study, the analgesic effect of peptides was determined and evaluated by in-vivo models. To characterize and quantitatively analyze these peptides, a reliable and efficient method combining size exclusion chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with amino acid analysis was developed. The peptides presented as a series of analogs with similar molecular weights mostly ranging from 2 to 8 kDa. The amino acid analysis by gas chromatography mass spectrometry (GC-MS) was developed to determine both free and combined amino acids (FAA and CAA) in cinobufacini injection. This method achieved good linearity (R(2) , 0.9909-0.9999) and low limit of detection and quantification. FAA and CAA samples were efficiently analyzed by modified Phenomenex EZ: faast procedure. For the sample analysis, the method showed good repeatability (relative standard deviation, RSD ≤ 10%). For most FAA and CAA the mean recoveries were >80% with RSD <10%. The GC-MS based method is useful for quality assurance of both FAA and CAA in cinobufacini injection. PMID:24924921

  9. Quantitative solid phase microextraction - gas chromatography mass spectrometry analysis of the pesticides lindane, heptachlor and two heptachlor transformation products in groundwater.

    PubMed

    McManus, Sarah-Louise; Coxon, Catherine E; Richards, Karl G; Danaher, Martin

    2013-04-01

    This paper describes the development and validation of a method for the determination of lindane, heptachlor and two heptachlor transformation products (exo- and endo-heptachlor epoxide) in groundwater. Samples were extracted using a simple solid phase microextraction (SPME) method with a polyacrylate fibre prior to detection by gas chromatography mass spectrometry in electron impact ionisation mode (GC-EI-MS). The linearity of the method ranged from 0.015 to 5.0 μg L(-1), with correlation coefficients greater than 0.99. Recoveries ranged from 96 to 101% at several fortification levels with all coefficients of variation (CV%) less than 10.5%. The method was validated to the permitted limits laid down in the European Union drinking water directive (98/83/EC). The limit of quantitation (LOQ) was 0.015 μg L(-1) in groundwater samples. Samples had to be analysed within 24h of collection otherwise degradation occurred and disposable SPME polyacrylate fibres lasted up to 51 injections. Both endo-heptachlor epoxide and lindane were detected in groundwater samples with concentrations ranging between 0.033 and 0.048 μg L(-1). PMID:23466207

  10. Determination of bisphenol A in water by micro liquid-liquid extraction followed by silylation and gas chromatography-mass spectrometry analysis.

    PubMed

    Gonzlez-Casado, A; Navas, N; del Olmo, M; Vlchez, J L

    1998-11-01

    A method for the determination of bisphenol A according to the European Union guideline, which establishes a limit of 0.1 ng/mL for organic pollutants in water, is proposed. The method involves a micro liquid-liquid extraction using dichloromethane followed by a silylation step. Identification and quantitation are performed with gas chromatography-mass spectrometry, using an HP-5MS column. The retention time is 7.02 min. Quantitation is carried out using single-ion monitoring (SIM) at m/z 73, 357, and 372. A clean-up is not necessary using SIM mode. Deuterated anthracene (2H10-anthracene) is used as an internal standard. The method is applied to the determination of bisphenol A at very low concentration levels (10.0-250.0 ng/L) in different types of natural water samples. The detection limit obtained is 0.4 ng/L. Recovery efficiencies are close to 100% in all cases. PMID:9812391

  11. Gas chromatography-mass spectrometry analysis of human mesenchymal stem cell metabolism during proliferation and osteogenic differentiation under different oxygen tensions.

    PubMed

    Muñoz, Nathalie; Kim, Junho; Liu, Yijun; Logan, Timothy M; Ma, Teng

    2014-01-01

    Bone marrow derived human mesenchymal stem cells (hMSC) are the primary cell type in bone tissue engineering, and their life span during osteogenic differentiation is associated with changes in oxygen tension. As a ubiquitous regulator of cellular metabolic activity, oxygen tension influences the profiles of metabolites in the entire metabolic network and plays an important role in hMSC survival, function, and osteogenic differentiation. In the current study, we hypothesize that hMSC have a metabolic phenotype that supports growth in low oxygen environments and that this phenotype changes upon differentiation, leading to differential responses to oxygen tension. We developed a gas chromatography-mass spectrometry (GC-MS) based metabolic profiling approach to analyze the metabolic fate of (13)C-glucose in glycolysis and the tricarboxylic acid cycle (TCA) in undifferentiated hMSC and hMSC-derived osteoblasts (hMSC-OS) in response to perturbation in oxygen tension; specifically we compared changes induced by culture under 20% vs. 2% O2. The isotope enrichments in the metabolites were calculated and used to infer activities of specific metabolic enzymes and the associated pathways. The results revealed contrasting metabolic profiles for hMSC and the hMSC-OS in both 20% and 2% O2 states, with the most significant differences involving coupling of glycolysis to the TCA cycle, glutaminolysis, and the malate-aspartate shuttle. The results have important implications in defining the optimal culture conditions for hMSC expansion and osteogenic differentiation. PMID:24269895

  12. Analysis of tramadol and O-desmethyltramadol in decomposed skeletal tissues following acute and repeated tramadol exposure by gas chromatography mass spectrometry.

    PubMed

    Wiebe, Treena R; Watterson, James H

    2014-09-01

    Decomposed bone and plasma samples of rats exposed to tramadol (TRAM) under different dosing patterns were analyzed. Wistar rats received TRAM as one acute dose (n=4, 45 mg/kg, i.p.) or three doses (n=4, 15 mg/kg, i.p.), 40 min apart. Perimortem heart blood was collected, rats were euthanized and placed outdoors to decompose to skeleton. Recovered bone was ground and subjected to methanolic extraction. Bone extracts and plasma samples underwent solid phase extraction and were analyzed using gas chromatography-mass spectrometry. Levels of TRAM and the primary metabolite O-desmethyltramadol (ODMT) were expressed as mass normalized response ratios (RR/m). Levels (RR/m) for TRAM and ODMT did not differ significantly between exposure types in any of the bone types examined or for the pooled bone comparisons (Mann-Whitney, p>0.05). However, ratios of analyte levels (RRTRAM/RRODMT) differed significantly between exposure patterns for tibial and skull bone as well as for pooled bone comparisons (Mann-Whitney, p<0.05). Levels of TRAM and ODMT, as well as ratios of analyte levels (RRTRAM/RRODMT), differed significantly in plasma between exposure patterns. Bone TRAM and ODMT levels were poorly correlated to corresponding plasma levels (TRAM: r=0.33-0.57; ODMT: r=-0.35-0.23). PMID:25112198

  13. 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

  14. Qualitative and Quantitative Analysis of Volatile Components of Zhengtian Pills Using Gas Chromatography Mass Spectrometry and Ultra-High Performance Liquid Chromatography.

    PubMed

    Liu, Cui-Ting; Zhang, Min; Yan, Ping; Liu, Hai-Chan; Liu, Xing-Yun; Zhan, Ruo-Ting

    2016-01-01

    Zhengtian pills (ZTPs) are traditional Chinese medicine (TCM) which have been commonly used to treat headaches. Volatile components of ZTPs extracted by ethyl acetate with an ultrasonic method were analyzed by gas chromatography mass spectrometry (GC-MS). Twenty-two components were identified, accounting for 78.884% of the total components of volatile oil. The three main volatile components including protocatechuic acid, ferulic acid, and ligustilide were simultaneously determined using ultra-high performance liquid chromatography coupled with diode array detection (UHPLC-DAD). Baseline separation was achieved on an XB-C18 column with linear gradient elution of methanol-0.2% acetic acid aqueous solution. The UHPLC-DAD method provided good linearity (R (2) ? 0.9992), precision (RSD < 3%), accuracy (100.68-102.69%), and robustness. The UHPLC-DAD/GC-MS method was successfully utilized to analyze volatile components, protocatechuic acid, ferulic acid, and ligustilide, in 13 batches of ZTPs, which is suitable for discrimination and quality assessment of ZTPs. PMID:26904360

  15. Qualitative and Quantitative Analysis of Volatile Components of Zhengtian Pills Using Gas Chromatography Mass Spectrometry and Ultra-High Performance Liquid Chromatography

    PubMed Central

    Liu, Cui-ting; Zhang, Min; Yan, Ping; Liu, Hai-chan; Liu, Xing-yun; Zhan, Ruo-ting

    2016-01-01

    Zhengtian pills (ZTPs) are traditional Chinese medicine (TCM) which have been commonly used to treat headaches. Volatile components of ZTPs extracted by ethyl acetate with an ultrasonic method were analyzed by gas chromatography mass spectrometry (GC-MS). Twenty-two components were identified, accounting for 78.884% of the total components of volatile oil. The three main volatile components including protocatechuic acid, ferulic acid, and ligustilide were simultaneously determined using ultra-high performance liquid chromatography coupled with diode array detection (UHPLC-DAD). Baseline separation was achieved on an XB-C18 column with linear gradient elution of methanol-0.2% acetic acid aqueous solution. The UHPLC-DAD method provided good linearity (R2 ≥ 0.9992), precision (RSD < 3%), accuracy (100.68–102.69%), and robustness. The UHPLC-DAD/GC-MS method was successfully utilized to analyze volatile components, protocatechuic acid, ferulic acid, and ligustilide, in 13 batches of ZTPs, which is suitable for discrimination and quality assessment of ZTPs. PMID:26904360

  16. Analysis of polycyclic aromatic hydrocarbons in aqueous samples by large volume injection gas chromatography-mass spectrometry using the through oven transfer adsorption desorption interface.

    PubMed

    Aragón, Álvaro; Toledano, Rosa M; Vázquez, Ana; Villén, Jesús; Cortés, José M

    2015-07-01

    A new procedure for the determination of 17 polycyclic aromatic hydrocarbons (PAHs) in aqueous samples by large volume injection-gas chromatography-mass spectrometry (LVI-GC-MS) using the Through Oven Transfer Adsorption Desorption (TOTAD) interface with nitrogen for solvent elimination is developed and validated. Up to 75mL of aqueous samples were injected to be sure that good solvent elimination were achieved, although 500µL were sufficient to achieve the required sensitivity.The performance of the developed method can be considered good: the relative standard deviation (RSD), (n=3) was lower than 13.8% for all the target analytes, the concentration of each PAH being 0.25μgL(-1), the limit of detection and limit of quantitation ranged from 21.5 to 211.0 ng L(-1) and from 71.7 to 703.3ngL(-1) respectively, and the correlation coefficients (R(2)) were all higher than 0.9764 in the 1-16μgL(-1) range. PMID:25882400

  17. 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

  18. 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...

  19. Quantitation of Phenol Levels in Oil of Wintergreen Using Gas Chromatography-Mass Spectrometry with Selected Ion Monitoring

    ERIC Educational Resources Information Center

    Sobel, Robert M.; Ballantine, David S.; Ryzhov, Victor

    2005-01-01

    Industrial application of gas chromatography-mass spectrometry (GC-MS) analysis is a powerful technique that could be used to elucidate components of a complex mixture while offering the benefits of high-precision quantitative analysis. The natural wintergreen oil is examined for its phenol concentration to determine the level of refining

  20. Quantitation of Phenol Levels in Oil of Wintergreen Using Gas Chromatography-Mass Spectrometry with Selected Ion Monitoring

    ERIC Educational Resources Information Center

    Sobel, Robert M.; Ballantine, David S.; Ryzhov, Victor

    2005-01-01

    Industrial application of gas chromatography-mass spectrometry (GC-MS) analysis is a powerful technique that could be used to elucidate components of a complex mixture while offering the benefits of high-precision quantitative analysis. The natural wintergreen oil is examined for its phenol concentration to determine the level of refining…

  1. Quantitative Thin-Layer Chromatography/Mass Spectrometry Analysis of Caffeine Using a Surface Sampling Probe Electrospray Ionization Tandem Mass Spectrometry System

    SciTech Connect

    Ford, Michael J; Deibel, Michael A.; Tomkins, Bruce A; Van Berkel, Gary J

    2005-01-01

    Quantitative determination of caffeine on reversed-phase C8 thin-layer chromatography plates using a surface sampling electrospray ionization system with tandem mass spectrometry detection is reported. The thin-layer chromatography/electrospray tandem mass spectrometry method employed a deuterium-labeled caffeine internal standard and selected reaction monitoring detection. Up to nine parallel caffeine bands on a single plate were sampled in a single surface scanning experiment requiring 35 min at a surface scan rate of 44 {mu}m/s. A reversed-phase HPLC/UV caffeine assay was developed in parallel to assess the mass spectrometry method performance. Limits of detection for the HPLC/UV and thin-layer chromatography/electrospray tandem mass spectrometry methods determined from the calibration curve statistics were 0.20 ng injected (0.50 {mu}L) and 1.0 ng spotted on the plate, respectively. Spike recoveries with standards and real samples ranged between 97 and 106% for both methods. The caffeine content of three diet soft drinks (Diet Coke, Diet Cherry Coke, Diet Pepsi) and three diet sport drinks (Diet Turbo Tea, Speed Stack Grape, Speed Stack Fruit Punch) was measured. The HPLC/UV and mass spectrometry determinations were in general agreement, and these values were consistent with the quoted values for two of the three diet colas. In the case of Diet Cherry Coke and the diet sports drinks, the determined caffeine amounts using both methods were consistently higher (by 8% or more) than the literature values.

  2. Comparison of photoacoustic radiometry to gas chromatography/mass spectrometry methods for monitoring chlorinated hydrocarbons

    SciTech Connect

    Sollid, J.E.; Trujillo, V.L.; Limback, S.P.; Woloshun, K.A.

    1996-03-01

    A comparison of two methods of gas chromatography mass spectrometry (GCMS) and a nondispersive infrared technique, photoacoustic radiometry (PAR), is presented in the context of field monitoring a disposal site. First is presented an historical account describing the site and early monitoring to provide an overview. The intent and nature of the monitoring program changed when it was proposed to expand the Radiological Waste Site close to the Hazardous Waste Site. Both the sampling methods and analysis techniques were refined in the course of this exercise.

  3. Magnetic nanoparticles of nitrogen enriched carbon (mnNEC) for analysis of pesticides and metabolites in zebrafish by gas chromatography-mass spectrometry.

    PubMed

    Zhou, Youe; Xia, Qian; Ding, Mengjie; Kageruka, Hubert; Jiang, Haiying; Jiang, Yan; Jing, Huifen; Xiao, Xiao; Zhong, Hongying

    2013-02-01

    Nanosized carbon based sorbents have been widely used for separation, enrichment and desalting of biological samples because of their distinguished characteristics. In this work, magnetic nanoparticles of nitrogen enriched carbon (mnNEC) have been developed for enrichment of organochlorine pesticide DDT and metabolite DDE that have been accumulated in zebrafish during the course of environmental exposure. Polymerization of pyrrole was performed in the aqueous suspension of Fe(3)O(4) nanoparticles. Resultant core-shell nanoparticules coated with polypyrrole were then subjected to a process of carbonization under high temperature and nitrogen atmospheric condition. The presence of nitrogen atoms in carbon nanoparticles increases the hydrophilicity and dispersability in aqueous samples. It has been experimentally demonstrated that mnNEC can be effectively dispersed in aqueous samples and rapidly isolated by the application of an external magnetic field. Recoveries of DDT and DDE from water range from 90% to 102% and 85-97% respectively. In combination with Selected Ion Monitoring (SIM) experiments of gas chromatography-mass spectrometry, the detection limit can be down to low ng/mL level. By using mnNEC approach, two interesting results have been found for zebrafish with 60 days exposure to DDT (1 μg/l). (1) There is higher concentration of DDT (37-143 ng/g) and DDE (173-1108 ng/g) in male zebrafish body tissues than that of female (7-52 ng/g and 146-362 ng/g for DDT and DDE respectively). (2) There is high ratio of DDE/DDT for both female and male zebrafish, implying high environmental persistence and ongoing bioaccumulation. PMID:23328251

  4. 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

  5. An Advanced Analytical Chemistry Experiment Using Gas Chromatography-Mass Spectrometry, MATLAB, and Chemometrics to Predict Biodiesel Blend Percent Composition

    ERIC Educational Resources Information Center

    Pierce, Karisa M.; Schale, Stephen P.; Le, Trang M.; Larson, Joel C.

    2011-01-01

    We present a laboratory experiment for an advanced analytical chemistry course where we first focus on the chemometric technique partial least-squares (PLS) analysis applied to one-dimensional (1D) total-ion-current gas chromatography-mass spectrometry (GC-TIC) separations of biodiesel blends. Then, we focus on n-way PLS (n-PLS) applied to…

  6. An Advanced Analytical Chemistry Experiment Using Gas Chromatography-Mass Spectrometry, MATLAB, and Chemometrics to Predict Biodiesel Blend Percent Composition

    ERIC Educational Resources Information Center

    Pierce, Karisa M.; Schale, Stephen P.; Le, Trang M.; Larson, Joel C.

    2011-01-01

    We present a laboratory experiment for an advanced analytical chemistry course where we first focus on the chemometric technique partial least-squares (PLS) analysis applied to one-dimensional (1D) total-ion-current gas chromatography-mass spectrometry (GC-TIC) separations of biodiesel blends. Then, we focus on n-way PLS (n-PLS) applied to

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

    USGS Publications Warehouse

    Sandstrom, Mark W.; Wydoski, Duane S.; Schroeder, Michael P.; Zamboni, Jana L.; Foreman, William T.

    1992-01-01

    A method for the isolation of organonitrogen herbicides from natural water samples using solid-phase extraction and analysis 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 cartridges containing octadecyl-bonded porous silica to remove the herbicides. The cartridges are dried using carbon dioxide, and adsorbed herbicides are removed from the cartridges by elution with 1.8 milliliters of hexaneisopropanol (3:1). Extracts of the eluants are analyzed by capillary-column gas chromatography/mass spectrometry with selected-ion monitoring of at least three characteristic ions. The method detection limits are dependent on sample matrix and each particular herbicide. The method detection limits, based on a 100-milliliter sample size, range from 0.02 to 0.25 microgram per liter. Recoveries averaged 80 to 115 percent for the 23 herbicides and 2 metabolites in 1 reagent-water and 2 natural-water samples fortified at levels of 0.2 and 2.0 micrograms per liter.

  8. MICELLAR ELECTROKINETIC CHROMATOGRAPHY-MASS SPECTROMETRY (R823292)

    EPA Science Inventory

    The combination of micellar electrokinetic chromatography (MEKC) with mass spectrometry (MS) is very attractive for the direct identification of analyte molecules, for the possibility of selectivity enhancement, and for the structure confirmation and analysis in a MS-MS mode. The...

  9. Analysis of inorganic species by capillary electrophoresis-mass spectrometry and ion exchange chromatography-mass spectrometry using an ion spray source.

    PubMed

    Corr, J J; Anacleto, J F

    1996-07-01

    Mixtures of inorganic ions separated by capillary electrophoresis (CE) and ion exchange chromatography (IC) are detected by mass spectrometry (MS) using an ion spray atmospheric pressure ionization source. The selectable degree of ion-adduct declustering and molecular fragmentation in the MS interface region allows the system to be operated as an elemental analyzer or as a molecular detector suitable for oxidation state determinations. Both inorganic anions and cations (including alkalis, alkaline earths, transition metals, and lanthanides) are analyzed by CE-MS. A variety of CE separation buffers are evaluated for the cation analyses (e.g., creatinine, ammonium acetate, and tris[hydroxymethyl]aminomethane). Only one of the buffers (i.e., creatinine) can be used for CE-indirect UV detection. A CE capillary permanently coated with strong anion exchange sites and a pyromellitic acid buffer (suitable for indirect UV detection) is used for the inorganic anion separations. The coated column eliminates the need for buffer modifiers to reverse the flow in the capillary, which then reduces background noise and mass spectral complexity. The separation and detection of 13 inorganic anions are also accomplished by IC using an anion exchange column with a carbonate-bicarbonate mobile phase, on-line suppressed conductivity detection, and mass spectrometric detection. PMID:21619300

  10. 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...

  11. 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 1.0μgmL(-1) total Merichem naphthenic acids was validated and demonstrated excellent accuracy (97-111% recovery) and precision (1.9% RSD at 0.02μgmL(-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 0.005μgmL(-1) total naphthenic acids with a precision <3.1% RSD and a calculated detection limit of 0.0004μgmL(-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

  12. Detection of new propofol metabolites in human urine using gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry techniques.

    PubMed

    Favetta, P; Dufresne, C; Désage, M; Païssé, O; Perdrix, J P; Boulieu, R; Guitton, J

    2000-01-01

    Using hyphenated analytical techniques, gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS), a study on minor propofol metabolites in human urine was conducted. These techniques allowed identification of two new phase I metabolites (2-(omega-propanol)-6-isopropylphenol and 2-(omega-propanol)-6-isopropyl-1,4-quinol). In addition, their four corresponding conjugates (three glucuronides and one sulphate) were detected. Thus in human urine at least eight conjugate metabolites are produced, derived from four different aglycones (propofol; 2, 6-diisopropyl-1,4-quinol; 2-(omega-propanol)-6-isopropylphenol and 2-(omega-propanol)-6-isopropyl-1,4-quinol). PMID:11013422

  13. Comprehensive analysis of a multidimensional liquid chromatography mass spectrometry dataset acquired on a quadrupole selecting, quadrupole collision cell, time-of-flight mass spectrometer: I. How much of the data is theoretically interpretable by search engines?

    PubMed

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

    2005-08-01

    An in-depth analysis of a multidimensional chromatography-mass spectrometry dataset acquired on a quadrupole selecting, quadrupole collision cell, time-of-flight (QqTOF) geometry instrument was carried out. A total of 3269 CID spectra were acquired. Through manual verification of database search results and de novo interpretation of spectra 2368 spectra could be confidently determined as predicted tryptic peptides. A detailed analysis of the non-matching spectra was also carried out, highlighting what the non-matching spectra in a database search typically are composed of. The results of this comprehensive dataset study demonstrate that QqTOF instruments produce information-rich data of which a high percentage of the data is readily interpretable. PMID:15923566

  14. Determination of hormonal growth promoters in bovine hair: comparison of liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry methods for estradiol benzoate and nortestosterone decanoate.

    PubMed

    Duffy, Eleanor; Rambaud, Lauriane; Le Bizec, Bruno; O'Keeffe, Michael

    2009-04-01

    The detection of steroid residues in hair is a powerful strategy to demonstrate long-term administration of these growth promoters in meat production animals. Analysis of the ester form of administered steroids is an unambiguous approach to prove the illegal use of natural hormones. For detection, gas chromatography-mass spectrometry (GC-MS/MS) was generally used. However, recent advances in liquid chromatography-tandem mass spectrometry (LC-MS/MS) technology have improved the robustness and potential sensitivity of this method. This paper describes development and validation, according to Commission Decision 2002/657/EC, of LC-MS/MS and GC-MS/MS methods, in two separate laboratories, for determination of steroid esters in bovine hair. Bovine hair samples taken from animals treated with estradiol-3-benzoate and nortestosterone decanoate, as well as from an untreated animal, were used to evaluate the comparability of the results of the two validated methods. The results of the inter-comparison demonstrate that both the LC-MS/MS and the GC-MS/MS methods are fit for purpose and capable of determining steroid esters in hair samples from treated bovine animals. PMID:19286025

  15. 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.

  16. ON SITE SOLID-PHASE EXTRACTION AND LABORATORY ANALYSIS OF ULTRA-TRACE SYNTHETIC MUSKS IN MUNICIPAL SEWAGE EFFLUENT USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY. FULL-SCAN MODE

    EPA Science Inventory

    Fragrance materials such as synthetic musks in aqueous samples, are normally determined by gas chromatography/mass spectrometry in the selected ion monitoring (SIM) mode to provide maximum sensitivity after liquid-liquid extraction of I -L samples. Full-scan mass spectra are requ...

  17. ON-SITE SOLID-PHASE EXTRACTION AND LABORATORY ANALYSIS OF ULTRA-TRACE SYNTHETIC MUSKS IN MUNICIPAL SEWAGE EFFLUENT USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY IN THE FULL-SCAN MODE

    EPA Science Inventory

    Fragrance materials such as synthetic musks in aqueous samples, are normally determined by gas chromatography/mass spectrometry in the selected ion monitoring (SIM) mode to provide maximum sensitivity after liquid-liquid extraction of I -L samples. Full-scan mass spectra are requ...

  18. Discrimination between tablet production methods using pyrolysis-gas chromatography-mass spectrometry and pattern recognition.

    PubMed

    Shen, Hailin; Carter, James F; Brereton, Richard G; Eckers, Christine

    2003-03-01

    Wet granulation and direct compression are two processes employed in tablet preparation. In this paper, pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) is used to discriminate these processes with the help of chemometric techniques. The data analysis procedure is as follows. First, deconvolute the Py-GC-MS data of each sample into concentration profiles and spectra, and then construct a matrix with each compound corresponding to one column; those contained only in a small number of samples are then removed. Second, the main principal components are kept after excluding three variables and one sample, and further processed by Fisher discriminant analysis. Third, the resultant data are assigned to classes using unsupervised and supervised classification methods. Results from cross-validation show that only 3 of 20 samples are misclassified by the Mahalanobis distance measure. PMID:12705389

  19. 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

  20. Gas chromatography/mass spectrometry for the determination of nitrosamines in red wine.

    PubMed

    Lona-Ramirez, Fernando J; Gonzalez-Alatorre, Guillermo; Rico-Ramírez, Vicente; Perez-Perez, Ma Cristina I; Castrejón-González, Edgar O

    2016-04-01

    N-nitrosamines (NAms) are highly active carcinogens that have been detected in food and beverages. Currently certain studies report their presence in red wine, while others fail to detect their presence. In this study the head space solid phase micro-extraction technique coupled to gas chromatography-mass spectrometry (HS-SPME-GC-MS) was applied to quantify four NAms in different types of red wine. The technique was found to be a simple, precise, fast and environmentally friendly alternative for the quantification of volatile NAms. A factorial analysis was carried out to evaluate the influence of the parameters on the HS-SPME technique. This is the first study that such analysis has been reported and where NAms in red wine have been quantified using HS-SPME-GC-MS. The method was validated by calculating the linearity, limit of detection and quantification. Two of the four NAms analyzed were found to be present in red wine samples. PMID:26593598

  1. Gas chromatography-mass spectrometry (GC-MS)-based metabolomics.

    PubMed

    Garcia, Antonia; Barbas, Coral

    2011-01-01

    Metabolic fingerprinting, the main tool in metabolomics, is a non-targeted methodology where all detectable peaks (or signals), including those from unknown analytes, are considered to establish sample classification. After pattern comparison, those signals changing in response to a specific situation under investigation are identified to gain biological insight. For this purpose, gas chromatographymass spectrometry (GC-MS) has a drawback in that only volatile compounds or compounds that can be made volatile after derivatization can be analysed, and derivatization often requires extensive sample treatment. However, once the analysis is focused on low molecular weight metabolites, GC-MS is highly efficient, sensitive, and reproducible. Moreover, it is quantitative, and its compound identification capabilities are superior to other separation techniques because GC-MS instruments obtain mass spectra with reproducible fragmentation patterns, which allow for the creation of public databases. This chapter describes well-established protocols for metabolic fingerprinting (i.e. the comprehensive analysis of small molecules) in plasma and urine using GC-MS. Guidelines will also be provided regarding subsequent data pre-treatment, pattern recognition, and marker identification. PMID:21207291

  2. Isolation, enrichment, and analysis of erythropoietins in anti-doping analysis by receptor-coated magnetic beads and liquid chromatography-mass spectrometry.

    PubMed

    Vogel, Matthias; Blobel, Mike; Thomas, Andreas; Walpurgis, Katja; Schnzer, Wilhelm; Reichel, Christian; Thevis, Mario

    2014-12-16

    Human erythropoietin (hEPO) is an erythropoiesis stimulating hormone frequently employed in antianemia therapy. Its capability to increase the amount of red blood cells however makes hEPO and its derivatives also attractive to dishonest athletes aiming at an artificial and illicit enhancement of their endurance performance. A major objective of the international antidoping fight is the elimination of drug misuse and prevention of severe adverse effects caused by nontherapeutic administrations of highly potent drugs. The emergence of novel and innovative erythropoietin-mimetic agents (EMAs) has been continuously growing in the last years, and the option of using dedicated monoclonal antibodies (mAb) for analytical and sample preparation approaches is gradually reaching limits. In the present study the common ability and property of all EMAs, to bind on the human erythropoietin receptor (hEPOR), is therefore exploited. An alternative methodology to isolate and analyze EMAs, in particular endogenous EPO and the recombinant forms EPOzeta, darbepoetin alfa, and C.E.R.A., from human urine is described, employing conventional ultrafiltration for preconcentration of the target analytes followed by EMA-specific isolation via hEPOR-bound magnetic beads. Analytical data were generated by means of gel-based electrophoretic analysis and nanoliquid chromatography/high resolution/high accuracy tandem mass spectrometry. Limits of detection enabled by the established sample preparation protocols were approximately 20 pg/mL for EPOzeta, 30 pg/mL for darbepoetin alfa, and 80 pg/mL for C.E.R.A. PMID:25423444

  3. 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), 17β-estradiol (E2) and 17α-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

  4. Gas chromatography/mass spectrometry and pyrolysis-gas chromatography/mass spectrometry for the chemical characterisation of modern and archaeological figs (Ficus carica).

    PubMed

    Ribechini, Erika; Pérez-Arantegui, Josefina; Colombini, Maria Perla

    2011-06-24

    Gas chromatography/mass spectrometry (GC/MS) after alkaline hydrolysis, solvent extraction and trimethylsilylation, and analytical pyrolysis using hexamethyldisilazane (HMDS) for in situ derivatisation followed by gas chromatographic/mass spectrometric analysis (Pyrolysis-silylation-GC/MS) were used to investigate the hydrolysable and soluble constituents, and the polymerised macromolecules of an archaeological fig (Ficus carica) recovered in Zaragoza (Spain), as well as of modern figs. The main aim was to study the compositional alterations undergone by the fig tissues in a particular archaeological environment: the fig was in a vessel and covered by a layer of a mixture of orpiment and gypsum. A comparison between the GC/MS results from modern and archaeological figs revealed that degradative reactions took place, leading to the disappearance/depletion of reactive (unsaturated fatty acids) and sensitive compounds (phytosterols and triterpenes). Py-silylation-GC/MS data provided evidence of a significant degradation of the saccharide and lipid components of the fig tissue, which left a residue enriched in polyphenols and polyesters. PMID:21570079

  5. 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.

  6. Profiling of plasma metabolites in canine oral melanoma using gas chromatography-mass spectrometry

    PubMed Central

    KAWABE, Mifumi; BABA, Yuta; TAMAI, Reo; YAMAMOTO, Ryohei; KOMORI, Masayuki; MORI, Takashi; TAKENAKA, Shigeo

    2015-01-01

    Malignant melanoma is one of the most common and aggressive tumors in the oral cavity of dog. The tumor has a poor prognosis, and methods for diagnosis and prediction of prognosis after treatment are required. Here, we examined metabolite profiling using gas chromatography-mass spectrometry (GC-MS) for development of a discriminant model for evaluation of prognosis. Metabolite profiles were evaluated in healthy and melanoma plasma samples using orthogonal projection to latent structure using discriminant analysis (OPLS-DA). Cases that were predicted to be healthy using the OPLS discriminant model had no advanced lesions after radiation therapy. These results indicate that metabolite profiling may be useful in diagnosis and prediction of prognosis of canine malignant melanoma. PMID:25843037

  7. Subsurface detection of fossil fuel pollutants by photoionization and gas chromatography/mass spectrometry.

    PubMed

    Robbat, Albert; Considine, Thomas; Antle, Patrick M

    2010-09-01

    This paper describes analysis of environmental pollutants at depth without bringing sample to the surface. It is based on an improved 3-stage Peltier freeze trap, which efficiently pre-concentrates volatile coal tar and petroleum hydrocarbons, and an integrated system for detecting pollutants on-line, in real-time by photoionization detection and quantitation by gas chromatography/mass spectrometry (GC/MS) as the probe is advanced into the subsurface. Findings indicate measurement precision and accuracy for volatiles meet EPA criteria for hazardous waste site investigations. When a Teflon membrane inlet is used to detect contaminants in groundwater, its 140 degrees C temperature limit restricts analyte collection in soil to C(2)-phenanthrenes. Two case studies demonstrate the probe is well-suited to tracking petroleum and coal tar plumes from source to groundwater. PMID:20594575

  8. Incorporation of Gas Chromatography-Mass Spectrometry into the Undergraduate Organic Chemistry Laboratory Curriculum

    ERIC Educational Resources Information Center

    Giarikos, Dimitrios G.; Patel, Sagir; Lister, Andrew; Razeghifard, Reza

    2013-01-01

    Gas chromatography-mass spectrometry (GC-MS) is a powerful analytical tool for detection, identification, and quantification of many volatile organic compounds. However, many colleges and universities have not fully incorporated this technique into undergraduate teaching laboratories despite its wide application and ease of use in organic…

  9. PERFORMANCE EVALUATION OF PARTICLE BEAM LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY FOR THE MEASUREMENT OF ACID HERBICIDES

    EPA Science Inventory

    Particle beam liquid chromatography/mass spectrometry (LC/MS) was evaluated for the measurement of acid herbicides. n acetic acid/ammonium acetate/methano1 solvent system with a C-8 reversed Phase column gave baseline resolution of all target analytes. etection limits in the full...

  10. Incorporation of Gas Chromatography-Mass Spectrometry into the Undergraduate Organic Chemistry Laboratory Curriculum

    ERIC Educational Resources Information Center

    Giarikos, Dimitrios G.; Patel, Sagir; Lister, Andrew; Razeghifard, Reza

    2013-01-01

    Gas chromatography-mass spectrometry (GC-MS) is a powerful analytical tool for detection, identification, and quantification of many volatile organic compounds. However, many colleges and universities have not fully incorporated this technique into undergraduate teaching laboratories despite its wide application and ease of use in organic

  11. 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…

  12. 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

  13. Perfusion reversed-phase high-performance liquid chromatography/mass spectrometry analysis of intact soybean proteins for the characterization of soybean cultivars.

    PubMed

    Castro-Rubio, Florentina; Marina, Ma Luisa; Garca, Ma Concepcin

    2007-11-01

    Perfusion reversed-phase HPLC (RP-HPLC)-electrospray mass spectrometry (ESI-MS) was employed for the characterization of soybean cultivars through the analysis of intact soybean proteins. The similarities and differences between yellow soybeans (the most usual soybeans) and other beans with different pigmentation (green, red, and black) commercialized as soybean were investigated. Red beans commercialized as azuki that are frequently sold as red soybean were also analyzed. Separation was carried out using a perfusion column at a flow-rate of 0.5 mL/min and a gradient elution. A step-by-step procedure was used for the optimization of the mass spectrometry parameters enabling the most sensitive detection. The method was applied to the analysis of the above-mentioned beans and the main soybean proteins (11S and 7S globulins) obtained by a fractionation procedure. MS spectra obtained from every peak in the beans and in their fractions were compared observing clear differences between yellow soybeans and the other beans with different pigmentation. The identification of some soybean proteins in yellow soybeans was also possible. PMID:17915236

  14. The detection of nicotine in a Late Mayan period flask by gas chromatography and liquid chromatography mass spectrometry methods.

    PubMed

    Zagorevski, Dmitri V; Loughmiller-Newman, Jennifer A

    2012-02-29

    Several ancient Mayan vessels from the Kislak Collection of the US Library of Congress were examined for the presence of alkaloids. One of them, a codex-style flask, bears a text that appears to read yo-'OTOT-ti 'u-MAY, spelling y-otoot 'u-may 'the home of its/his/her tobacco'. Samples extracted from this Late Classic period (600 to 900 AD) container were analyzed by gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS) methods. Nicotine was identified as the major component of the extracts. LC/MS analyses also yielded signals due to nicotine mono-oxides. The identities of the compounds were determined by comparison of the chromatographic and/or mass spectral characteristics with those from standards and literature data. High-resolution high mass accuracy tandem mass spectrometry (MS/MS) spectra of protonated nicotine and nicotine mono-oxides were measured to verify and to correct previous product ion assignments. These analyses provided positive evidence for nicotine from a Mayan vessel, indicating it as a likely holder of tobacco leafs. The result of this investigation is the first physical evidence of tobacco from a Mayan container, and only the second example where the vessel content recorded in a Mayan hieroglyphic text has been confirmed directly by chromatography/mass spectrometry trace analysis. PMID:22279016

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

    NASA Astrophysics Data System (ADS)

    Compton, Duane C.; Snapp, Robert R.

    2007-09-01

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

  16. Robust Algorithm for Alignment of Liquid Chromatography-Mass Spectrometry Analyses in an Accurate Mass and Time Tag Data Analysis Pipeline

    SciTech Connect

    Jaitly, Navdeep; Monroe, Matthew E.; Petyuk, Vladislav A.; Clauss, Therese RW; Adkins, Joshua N.; Smith, Richard D.

    2006-11-01

    Liquid chromatography coupled to mass spectrometry (LC-MS) and tandem mass spectrometry (LC-MS/MS) has become a standard technique for analyzing complex peptide mixtures to determine composition and relative quantity. Several high-throughput proteomics techniques attempt to combine complementary results from multiple LC-MS and LC-MS/MS analyses to provide more comprehensive and accurate results. To effectively collate results from these techniques, variations in mass and elution time measurements between related analyses are corrected by using algorithms designed to align the various types of results: LC-MS/MS vs. LC-MS/MS, LC-MS vs. LC-MS/MS, and LC-MS vs. LC-MS. Described herein are new algorithms referred to collectively as Liquid Chromatography based Mass Spectrometric Warping and Alignment of Retention times of Peptides (LCMSWARP) which use a dynamic elution time warping approach similar to traditional algorithms that correct variation in elution time using piecewise linear functions. LCMSWARP is compared to a linear alignment algorithm that assumes a linear transformation of elution time between analyses. LCMSWARP also corrects for drift in mass measurement accuracies that are often seen in an LC-MS analysis due to factors such as analyzer drift. We also describe the alignment of LC-MS results and provide examples of alignment of analyses from different chromatographic systems to demonstrate more complex transformation functions.

  17. Recent developments in liquid chromatography-mass spectrometry and related techniques.

    PubMed

    Holčapek, Michal; Jirásko, Robert; Lísa, Miroslav

    2012-10-12

    This review summarizes the state-of-art in liquid chromatography-mass spectrometry (LC-MS) and related techniques with the main focus on recent developments in the last decade. LC-MS records an enormous growth in recent years due to the application potential in analytical chemistry, biochemistry, pharmaceutical analysis, clinical analysis and many other fields, where the qualitative and quantitative characterization of complex organic, bioorganic and organometallic mixtures is needed. Beginners and moderately experienced LC-MS users may be confused by the number of different LC-MS systems on the market, therefore an actual overview of mass spectrometers designed for the LC-MS configuration and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) from main manufacturers is compiled here together with an independent assessment of their advantages and limitations. Current trends in terms of mass analyzers, ionization techniques, fast LC-MS, LC-MALDI-MS, ion mobility spectrometry used in LC-MS, quantitation issues specific to MS and emerging mass spectrometric approaches complementary to LC-MS are discussed as well. PMID:22959775

  18. Direct thermal desorption in the analysis of cheese volatiles by gas chromatography and gas chromatography-mass spectrometry: comparison with simultaneous distillation-extraction and dynamic headspace.

    PubMed

    Valero, E; Sanz, J; Martínez-Castro, I

    2001-06-01

    Direct thermal desorption (DTD) has been used as a technique for extracting volatile components of cheese as a preliminary step to their gas chromatographic (GC) analysis. In this study, it is applied to different cheese varieties: Camembert, blue, Chaumes, and La Serena. Volatiles are also extracted using other techniques such as simultaneous distillation-extraction and dynamic headspace. Separation and identification of the cheese components are carried out by GC-mass spectrometry. Approximately 100 compounds are detected in the examined cheeses. The described results show that DTD is fast, simple, and easy to automate; requires only a small amount of sample (approximately 50 mg); and affords quantitative information about the main groups of compounds present in cheeses. PMID:11396685

  19. Gas chromatography/mass spectrometry methods applied for the analysis of a Round Robin sample containing materials present in samples of works of art

    NASA Astrophysics Data System (ADS)

    van Keulen, Henk

    2009-07-01

    The Users' Group for Mass Spectrometry and Chromatography (MaSC) was established as a discussion forum for scientists involved in the study of artworks and cultural artefacts who wish to exchange information regarding sampling strategies and protocols, preparation of samples, chromatographic and mass spectrometric analysis, data treatment and interpretation of results. Comparing protocols and different approaches to the interpretation of results requires the use of standard reference materials and Round Robin tests. To this end, an artificial, complex Round Robin sample was sent to fifteen laboratories specializing in the analysis of cultural materials. Ten of the participants analyzed the sample and reported their results, which were anonymously discussed at the MaSC meeting in Philadelphia, September 2007. In this paper, the results of the confirming GC/MS analysis of the sample by the author are presented and compared with the results of the participants. The confirming analysis was performed with thermally assisted hydrolysis and methylation GC/MS in combination with pyrolysis, and by a combined method for the analysis of proteins and carbohydrates. A number of different instrumental setups and methods were used by the Round Robin participants. The results show that stepwise extraction followed by different types of derivatization is a successful approach for the analysis and identification of complex samples. A disadvantage is the need for relatively large samples, which are not always available in practice. Pyrolysis with or without tetramethylammonium hydroxide (TMAH) or hexamethyldisilazane (HMDS) was used by four of the participants. The results show that thermally assisted hydrolysis and methylation GC/MS in combination with pyrolysis is a powerful technique for the analysis of multi-component samples. The presence of gums and proteins can be indicated. Synthetic resins such as acrylics can also be analyzed in combination with the traditional binders and resins.

  20. Pentafluorobenzyl esterification of haloacetic acids in tap water for simple and sensitive analysis by gas chromatography/mass spectrometry with negative chemical ionization.

    PubMed

    Zhao, Can; Fujii, Yukiko; Yan, Junxia; Harada, Kouji H; Koizumi, Akio

    2015-01-01

    Chlorine is the most widely used disinfectant for control of waterborne diseases in drinking water treatment. It can react with natural organic matter in water and form haloacetic acids (HAAs). For analysis of HAA levels, derivatization with diazomethane is commonly recommended as the standard methodology in Japan. However, diazomethane is a carcinogenic alkylating agent. Therefore, in this study, a safe, simple, and sensitive quantification method was developed to monitor HAAs in drinking water. Pentafluorobenzyl esterification was used for pretreatment. The pentafluorobenzyl-ester derivative was detected by gas chromatography-negative ion chemical ionization-mass spectrometry analysis with very high sensitivity for HAAs analysis. The method has low detection limits (8-94 ng L(-1)) and good recovery rates (89-99%) for HAAs. The method was applied to 30 tap water samples from 15 cities in the Kansai region of Japan. The levels of HAAs detected were in the range 0.54-7.83 μg L(-1). Dichloroacetic acid, trichloroacetic acid, and bromochloroacetic acid were the major HAAs detected in most of the tap water, and accounted for 29%, 20% and 19% of the total HAAs, respectively. This method could be used for routine monitoring of HAAs in drinking water without exposure of workers to occupational hazards. PMID:25180822

  1. Direct identification of rituximab main isoforms and subunit analysis by online selective comprehensive two-dimensional liquid chromatography-mass spectrometry.

    PubMed

    Stoll, Dwight R; Harmes, David C; Danforth, John; Wagner, Elsa; Guillarme, Davy; Fekete, Szabolcs; Beck, Alain

    2015-08-18

    In this proof-of-concept study, rituximab, which is a reference therapeutic monoclonal antibody (mAb), was characterized through the implementation of online, selective comprehensive two-dimensional liquid chromatography (sLC×LC) coupled with mass spectrometry (MS), using a middle-up approach. In this setup, cation exchange chromatography (CEX) and reverse-phase liquid chromatography (RPLC) were used as the first and second separation dimensions, respectively. As illustrated in this work, the combination of these two chromatographic modes allows a direct assignment of the identities of CEX peaks, using data from the TOF/MS detector, because RPLC is directly compatible with MS detection, whereas CEX is not. In addition, the resolving power of CEX is often considered to be limited; therefore, this 2D approach provides an improvement in peak capacity and resolution when high-performance second-dimension separations are used, instead of simply using the second-dimension separation as a desalting step. This was particularly relevant when separating rituximab fragments of medium size (25 kDa), whereas most of the resolution was provided by CEX in the case of intact rituximab samples. The analysis of a commercial rituximab sample shows that online sLC×LC-TOF-MS can be used to rapidly characterize mAb samples, yielding the identification of numerous variants, based on the analysis of intact, partially digested, and digested/reduced mAb samples. PMID:26145446

  2. Development of a method for metabolomic analysis of human exhaled breath condensate by gas chromatography-mass spectrometry in high resolution mode.

    PubMed

    Peralbo-Molina, A; Calderón-Santiago, M; Priego-Capote, F; Jurado-Gámez, B; Luque de Castro, M D

    2015-08-01

    Exhaled breath condensate (EBC) is a promising biofluid scarcely used in clinical analysis despite its non-invasive sampling. The main limitation in the analysis of EBC is the lack of standardized protocols to support validation studies. The aim of the present study was to develop an analytical method for analysis of human EBC by GC-TOF/MS in high resolution mode. Thus, sample preparation strategies as liquid-liquid extraction and solid-phase extraction were compared in terms of extraction coverage. Liquid-liquid extraction resulted to be the most suited sample preparation approach providing an average extraction efficiency of 77% for all compounds in a single extraction. Different normalization approaches were also compared to determine which strategy could be successfully used to obtain a normalized profile with the least variability among replicates of the same sample. Normalization to the total useful mass spectrometry signal (MSTUS) proved to be the most suited strategy for the analysis of EBC from healthy individuals (n = 50) reporting a within-day variability below 7% for the 51 identified compounds and a suited data distribution in terms of percentage of metabolites passing the Skewness and Kurtosis test for normality distribution. The composition of EBC was clearly dominated by the presence of fatty acids and derivatives such as methyl esters and amides, and volatile prenol lipids. Therefore, EBC offers the profile of both volatile and non-volatile components as compared to other similar biofluids such as exhaled breath vapor, which only provides the volatile profile. This human biofluid could be an alternative to others such as serum/plasma, urine or sputum to find potential markers with high value for subsequent development of screening models. PMID:26320793

  3. Towards smaller and faster gas chromatography-mass spectrometry systems for field chemical detection.

    PubMed

    Smith, P A; Sng, M T; Eckenrode, B A; Leow, S Y; Koch, D; Erickson, R P; Jackson Lepage, C R; Hook, G L

    2005-03-01

    Gas chromatography-mass spectrometry (GC-MS) is already an important laboratory method, but new sampling techniques and column heating approaches will expand and improve its usefulness for detection and identification of unknown chemicals in field settings. In order to demonstrate commercially-available technical advances for both sampling and column heating, we used solid phase microextraction (SPME) sampling of both water and air systems, followed by immediate analysis with a resistively heated analytical column and mass spectrometric detection. High-concern compounds ranging from 140 to 466 amu were analyzed to show the applicability of these techniques to emergency situations impacting public health. A field portable (about 35 kg) GC-MS system was used for analysis of water samples with a resistively heated analytical column externally mounted as a retrofit using the air bath oven of the original instrument design to heat transfer lines. The system used to analyze air samples included a laboratory mass spectrometer with a dedicated resistive column heating arrangement (no legacy air bath column oven). The combined sampling and analysis time was less than 10 min for both air and water sample types. By combining dedicated resistive column heating with smaller mass spectrometry systems designed specificallyfor use in the field, substantially smaller high performance field-portable instrumentation will be possible. PMID:15844534

  4. Comparison and analysis of organochlorine pesticides and hexabromobiphenyls in environmental samples by gas chromatography-electron capture detector and gas chromatography-mass spectrometry.

    PubMed

    Liu, Yu; Fu, Xiaofang; Tao, Shu; Liu, Liang; Li, Wei; Meng, Bingjun

    2015-02-01

    Two analytical methods, gas chromatography-electron capture detector (GC-ECD) and gas chromatography-negative chemical ionization-mass spectrometry (GC-NCI-MS), were evaluated and compared for the measurement of persistent organic pollutants, specifically for 26 organochlorine pesticides and two hexabromobiphenyls, in atmospheric particulate matter and soil samples. The hypothesis tested was that the coelution of non-target compounds may lead to false positives when analyzed by GC-ECD, and that the overestimation associated with these false positives can be eliminated using GC-NCI-MS. The study showed that both methods had satisfactory linearity and reproducibility for the target compounds. Although the sensitivities of GC-ECD for most of the compounds investigated were higher than those observed with the GC-NCI-MS method, the matrices interference was obvious with GC-ECD. There was indeed an apparently high false-positive rate or overestimate when GC-ECD was used for environmental samples, implying that the GC-ECD method has been used with care and that GC-NCI-MS is generally superior for the analysis of trace amounts of these compounds in environmental samples. Based on these results, the sample extraction and cleanup procedures of the GC-NCI-MS method were optimized for achieving acceptable recoveries and less matrices interference. PMID:24872522

  5. 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.

  6. Analysis and quantitation of volatile organic compounds emitted from plastics used in museum construction by evolved gas analysis-gas chromatography-mass spectrometry.

    PubMed

    Samide, Michael J; Smith, Gregory D

    2015-12-24

    Construction materials used in museums for the display, storage, and transportation of artwork must be assessed for their tendency to emit harmful pollution that could potentially damage cultural treasures. Traditionally, a subjective metals corrosion test known as the Oddy test has been widely utilized in museums for this purpose. To augment the Oddy test, an instrumental sampling approach based on evolved gas analysis (EGA) coupled to gas chromatography (GC) with mass spectral (MS) detection has been implemented for the first time to qualitatively identify off-gassed pollutants under specific conditions. This approach is compared to other instrumental methods reported in the literature. This novel application of the EGA sampling technique yields several benefits over traditional testing, including rapidity, high sensitivity, and broad detectability of volatile organic compounds (VOCs). Furthermore, unlike other reported instrumental approaches, the EGA method was used to determine quantitatively the amount of VOCs emitted by acetate resins and polyurethane foams under specific conditions using both an external calibration method as well as surrogate response factors. EGA was successfully employed to rapidly characterize emissions from 12 types of common plastics. This analysis is advocated as a rapid pre-screening method to rule out poorly performing materials prior to investing time and energy in Oddy testing. The approach is also useful for rapid, routine testing of construction materials previously vetted by traditional testing, but which may experience detrimental formulation changes over time. As an example, a case study on batch re-orders of rigid expanded poly(vinyl chloride) board stock is presented. PMID:26687162

  7. Tandem Extraction/Liquid Chromatography-Mass Spectrometry Protocol for the Analysis of Acrylamide and Surfactant-related Compounds in Complex Aqueous Environmental Samples

    EPA Science Inventory

    The development of a liquid chromatography‐mass spectrometry (LC‐MS)‐based strategy for the detection and quantitation of acrylamide and surfactant‐related compounds in aqueous complex environmental samples.

  8. Use of spermine and thiabendazole as analyte protectants to improve direct analysis of 16 carbamates by gas chromatography-mass spectrometry in green vegetable matrices.

    PubMed

    Przybylski, Cédric; Bonnet, Véronique

    2009-06-01

    The carbamates are a well-known thermosensible pesticides class, which are highly prone to degradation via fragmentation and/or rearrangement mechanisms leading to a difficult direct gas chromatography (GC) analysis, i.e., without derivatization. In this paper, spermine and thiabendazole both at 1 mg/mL were highlighted as efficient analyte protectants to improve the direct and simultaneous analysis of 16 carbamates both in solvent and green vegetable matrices. These two molecules were compared in mixture or in combination with three well-known efficient analyte protectants 3-ethoxy-1,2-propanediol, D-sorbitol, and L-gulonic acid-gamma-lactone. The potential benefits were investigated in GC hyphenated to mass spectrometry (GC-MS) with two injection modes: programmable temperature vaporizing injector in a solvent split mode (PTV-SSI) and on-column injection (OCI). It was shown that the combined effect of the five protective agents led to the best sensitivity improvement with limits of detection between 0.1-0.4 and 0.03-0.1 microg/kg and limits of quantification between 0.3-1.1 and 0.1-0.5 microg/kg for PTV-SSI and OCI mode, respectively. The correlation coefficients from the analyzed 1-500 microg/kg range were all >0.999 both in the solvent and matrices studied. The recoveries of carbamates from three spiked matrices over five replicates at 20 and 100 microg/kg were in the range 90-107% with relative standard deviation (RSD) equal to 2-7% for PTV-SSI and 92-107% with an RSD equal to 1-6% for OCI. The use of spermine and thiabendazole with other analyte protectants shows very efficient partial or total reduction of breakdown of the most sensitive carbamates such as the N-sulfenylated ones. PMID:19415245

  9. Sensitive Determination of Onco-metabolites of D- and L-2-hydroxyglutarate Enantiomers by Chiral Derivatization Combined with Liquid Chromatography/Mass Spectrometry Analysis

    PubMed Central

    Cheng, Qing-Yun; Xiong, Jun; Huang, Wei; Ma, Qin; Ci, Weimin; Feng, Yu-Qi; Yuan, Bi-Feng

    2015-01-01

    2-hydroxyglutarate (2HG) is a potent competitor of α-ketoglutarate (α-KG) and can inhibit multiple α-KG dependent dioxygenases that function on the epigenetic modifications. The accumulation of 2HG contributes to elevated risk of malignant tumors. 2HG carries an asymmetric carbon atom in its carbon backbone and differentiation between D-2-hydroxyglutarate (D-2HG) and L-2-hydroxyglutarate (L-2HG) is crucially important for accurate diagnosis of 2HG related diseases. Here we developed a strategy by chiral derivatization combined with liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) analysis for highly sensitive determination of D-2HG and L-2HG enantiomers. N-(p-toluenesulfonyl)-L-phenylalanyl chloride (TSPC) was used to derivatize 2HG. The formed diastereomers by TSPC labeling can efficiently improve the chromatographic separation of D-2HG and L-2HG. And derivatization by TSPC could also markedly increase the detection sensitivities by 291 and 346 folds for D-2HG and L-2HG, respectively. Using the developed method, we measured the contents of D-2HG and L-2HG in clear cell renal cell carcinoma (ccRCC) tissues. We observed 12.9 and 29.8 folds increase of D-2HG and L-2HG, respectively, in human ccRCC tissues compared to adjacent normal tissues. The developed chiral derivatization combined with LC-ESI-MS/MS analysis offers sensitive determination of D-2HG and L-2HG enantiomers, which benefits the precise diagnosis of 2HG related metabolic diseases. PMID:26458332

  10. 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.

  11. Methods of Analysis by the U.S. Geological Survey Organic Geochemistry Research Group?Determination of acetamide herbicides and their degradation products in water using online solid-phase extraction and liquid chromatography/mass spectrometry

    USGS Publications Warehouse

    Lee, E.A.; Strahan, A.P.

    2003-01-01

    An analytical method for the determination of 6 acetamide herbicides (acetochlor, alachlor, dimethenamid, flufenacet, metolachlor, and propachlor) and 16 of their degradation products in natural water samples using solid-phase extraction and liquid chromatography/mass spectrometry is described 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 octadecylsilane as the solid-phase extraction media on online automated equipment followed by liquid chromatography/mass spectrometry. The method uses only 10 milliliters of sample per injection. Three different water-sample matrices, a reagent-water, a ground-water, and a surface-water sample spiked at 0.10 and 1.0 microgram per liter, were analyzed to determine method performance. Method detection limits ranged from 0.004 to 0.051 microgram per liter for the parent acetamide herbicides and their degradation products. Mean recoveries for the acetamide compounds in the ground- and surface-water samples ranged from 62.3 to 117.4 percent. The secondary amide of acetochlor/metolachlor ethanesulfonic acid (ESA) was recovered at an average rate of 43.5 percent. The mean recoveries for propachlor and propachlor oxanilic acid (OXA) were next lowest, ranging from 62.3 to 95.5 percent. Mean recoveries from reagent-water samples ranged from 90.3 to 118.3 percent for all compounds. Overall the mean of the mean recoveries of all compounds in the three matrices spiked at 0.10 and 1.0 microgram per liter ranged from 89.9 to 100.7 percent, including the secondary amide of acetochlor/metolachlor ESA and the propachlor compounds. The acetamide herbicides and their degradation products are reported in concentrations ranging from 0.05 to 2.0 micrograms per liter. The upper concentration limit is 2.0 micrograms per liter for all compounds without dilution. With the exception of the secondary amide of acetochlor/metolachlor ESA, good precision and accuracy for the chloroacetanalide herbicides and their degradation compounds were demonstrated for the method in buffered reagent water, ground water, and surface water. The extraction method as used did not optimize the recovery of the secondary amide of acetochlor/metolachlor ESA.

  12. Advanced Capillary Liquid Chromatography-Mass Spectrometry for Proteomics

    SciTech Connect

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

    2009-02-23

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

  13. In-tube solid-phase microextraction based on hybrid silica monolith coupled to liquid chromatography-mass spectrometry for automated analysis of ten antidepressants in human urine and plasma.

    PubMed

    Zheng, Ming-Ming; Wang, Shao-Ting; Hu, Wei-Kang; Feng, Yu-Qi

    2010-11-26

    A rapid, sensitive and automated in-tube solid-phase microextraction-liquid chromatography-mass spectrometry (in-tube SPME/LC-MS) method was developed for the analysis of ten antidepressants in urine and plasma. A hybrid organic-inorganic silica monolith with cyanoethyl functional groups was prepared and used as a sorbent for in-tube SPME. Integration of the sample extraction, LC separation and MS detection into a single system permitted direct injection of the diluted urine or plasma after filtration. Under the optimized conditions, good extraction efficiencies for the targets were obtained with no matrix interference in the subsequent LC-MS. Automation of the sampling, extraction and separation procedures was realized under the control of a program in this study. The total process time was 30 min and only 30 ?L of urine or plasma was required in one analysis cycle. Good linearities were obtained for ten antidepressants with the correlation coefficients (R) above 0.9933. The limits of detection (S/N=3) for ten antidepressants were found to be 0.06-2.84 ng/mL in urine and 0.07-2.95 ng/mL in plasma. The recoveries of antidepressants spiked in urine and plasma were from 75.2% to 113.0%, with relative standard deviations less than 16.5%. The developed method was successfully used to analyze urine sample from ageing patients undergoing therapy with antidepressants. PMID:20980013

  14. Construction and analysis of correlation networks based on gas chromatography-mass spectrometry metabonomics data for lipopolysaccharide-induced inflammation and intervention with volatile oil from Angelica sinensis in rats.

    PubMed

    Hua, Yong-li; Ji, Peng; Xue, Zi-yu; Wei, Yan-ming

    2015-11-01

    Angelica sinensis (AS) is a well-known important traditional Chinese medicine that yields a volatile oil with anti-inflammatory effects. However, the holistic therapeutic effects and the mechanism underlying such effects of the volatile oil of A. sinensis (VOAS) are not yet well understood. Here, a gas chromatography-mass spectrometry-based metabonomic study was conducted to explore the significantly altered metabolites for better understanding of VOAS and to assess the integral efficacy of VOAS on a lipopolysaccharide (LPS)-induced inflammation rat model. Principal component analysis was used to investigate the global metabonomic alterations and to evaluate the therapeutic effects of VOAS in rats. Clear separations were observed in the comparison of the metabolite profiles of the normal control (NC) group, the LPS-stimulated group (MI), the VOAS group, and the dexamethasone (Dex) group. VOAS exerted therapeutic effects on the LPS-stimulated group, which were in accordance with the results of cytokine analyses and blood physiobiochemical assay. Furthermore, a total of 20, 17, and 22 metabolites distributed in 27 metabolic pathways were respectively identified in plasma, liver, and lung samples as significantly altered metabolites of MI, VOAS, Dex, and NC of the same background. Network analysis revealed that glycine, glutamate, malic acid, succinate, arachidonic acid, glycerol, galactose, and glucose were hub metabolites of the inflammation correlation network. Results indicated that VOAS exhibited an anti-inflammatory effect by adjusting the Krebs cycle, improving the glucose content, and restoring the fatty acid metabolism. PMID:26399193

  15. Protocol for liquid chromatography/mass spectrometry of glutathione conjugates using postcolumn solvent modification.

    PubMed

    Bean, M F; Pallante-Morell, S L; Dulik, D M; Fenselau, C

    1990-01-15

    A novel protocol for thermospray liquid chromatography/mass spectrometry (LC/MS) analysis of mixtures of glutathione conjugates is reported. Solvent conditions for optimal high-performance liquid chromatography are not always the same as for optimal thermospray ionization mass spectrometry. Labile glutathione conjugates that give poor spectra in aqueous ammonium acetate yield more intense molecular ion signals with increased percentages of acetonitrile. Direct injection thermospray ionization using 30-60% acetonitrile in aqueous ammonium acetate produced protonated molecular ions for glutathione conjugates of menadione, styrene oxide, pentachlorophenyl methyl sulfone, chlorodinitrobenzene, and chlorambucil. Since, the high percentages of organic modifier needed for good molecular ion intensity preclude chromatographic separation of these polar compounds, successful graphic separation of these polar compounds, successful LC/MS was facilitated by postcolumn addition of organic modifiers to the mobile phase. This new methodology allowed excellent chromatographic separations and thermospray ionization mass spectra to be obtained for a mixture of haloalkane glutathione conjugates. Moreover, cleavage of the gamma-glutamyl-cysteine amide bond of glutathione results in class-characteristic fragment ions. Changes in the fragmentation pathways in spectra acquired with and without organic modifiers shed light on the importance of the desolvation process in obtaining good molecular ion sensitivity in thermospray. PMID:2310009

  16. Isotope Ratio Monitoring Gas Chromatography Mass Spectrometry (IRM-GCMS)

    NASA Technical Reports Server (NTRS)

    Freeman, K. H.; Ricci, S. A.; Studley, A.; Hayes, J. M.

    1989-01-01

    On Earth, the C-13 content of organic compounds is depleted by roughly 13 to 23 permil from atmospheric carbon dioxide. This difference is largely due to isotope effects associated with the fixation of inorganic carbon by photosynthetic organisms. If life once existed on Mars, then it is reasonable to expect to observe a similar fractionation. Although the strongly oxidizing conditions on the surface of Mars make preservation of ancient organic material unlikely, carbon-isotope evidence for the existence of life on Mars may still be preserved. Carbon depleted in C-13 could be preserved either in organic compounds within buried sediments, or in carbonate minerals produced by the oxidation of organic material. A technique is introduced for rapid and precise measurement of the C-13 contents of individual organic compounds. A gas chromatograph is coupled to an isotope-ratio mass spectrometer through a combustion interface, enabling on-line isotopic analysis of isolated compounds. The isotope ratios are determined by integration of ion currents over the course of each chromatographic peak. Software incorporates automatic peak determination, corrections for background, and deconvolution of overlapped peaks. Overall performance of the instrument was evaluated by the analysis of a mixture of high purity n-alkanes of know isotopic composition. Isotopic values measured via IRM-GCMS averaged withing 0.55 permil of their conventionally measured values.

  17. 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…

  18. 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

  19. Variability of matrix effects in liquid and gas chromatography - mass spectrometry analysis of pesticide residues after QuEChERS sample preparation of different food crops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Gas and liquid chromatography (GC and LC) coupled to sophisticated mass spectrometry (MS) instruments are among the most powerful analytical tools currently available to monitor pesticide residues in food, among other applications. However, both GC-MS and LC-MS are susceptible to matrix effects whi...

  20. 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.

  1. Methods of analysis and quality-assurance practices of the U.S. Geological Survey organic laboratory, Sacramento, California; determination of pesticides in water by solid-phase extraction and capillary-column gas chromatography/mass spectrometry

    USGS Publications Warehouse

    Crepeau, Kathryn L.; Domagalski, Joseph L.; Kuivila, Kathryn M.

    1994-01-01

    Analytical method and quality-assurance practices were developed for a study of the fate and transport of pesticides in the Sacramento-San Joaquin Delta and the Sacramento and San Joaquin River. Water samples were filtered to remove suspended parti- culate matter and pumped through C-8 solid-phase extraction cartridges to extract the pesticides. The cartridges were dried with carbon dioxide, and the pesticides were eluted with three 2-milliliter aliquots of hexane:diethyl ether (1:1). The eluants were analyzed using capillary-column gas chromatography/mass spectrometry in full-scan mode. Method detection limits for analytes determined per 1,500-milliliter samples ranged from 0.006 to 0.047 microgram per liter. Recoveries ranged from 47 to 89 percent for 12 pesticides in organic-free, Sacramento River and San Joaquin River water samples fortified at 0.05 and 0.26 microgram per liter. The method was modified to improve the pesticide recovery by reducing the sample volume to 1,000 milliliters. Internal standards were added to improve quantitative precision and accuracy. The analysis also was expanded to include a total of 21 pesticides. The method detection limits for 1,000-milliliter samples ranged from 0.022 to 0.129 microgram per liter. Recoveries ranged from 38 to 128 percent for 21 pesticides in organic-free, Sacramento River and San Joaquin River water samples fortified at 0.10 and 0.75 microgram per liter.

  2. Peptide analysis as amino alcohols by gas chromatography-mass spectrometry. Application to hyperoligopeptiduria. Detection of Gly-3Hyp-4Hyp and Gly-Pro-4Hyp-Gly.

    PubMed

    Steiner, W; Niederwieser, A

    1979-03-15

    A method for the qualitative analysis of oligopeptides in human urine in cases of peptiduria is described. After sample precleaning on a strongly acidic ion exchanger, the trifluoroacetyl/methyl esters were formed and the peptide derivatives were transformed into trifluoroethyl oligoamino alcohols according to Nau and Biemann. It was found that oligoamino alcohols could be isolated selectively on a weakly acidic ion exchanger. The O-trimethylsilylated trifluoroethyl oligoamino alcohols were separated on a SE-30 glass capillary column and analyzed by computer-assisted gas chromatography-mass spectrometry. In order to increase specificity and to facilitate mass spectrometric interpretation, aliquots of the sample were reduced separately with lithium-aluminium deuteride and hydride. Each peptide gave a pair of derivatives with characteristic mass differences of the ions, namely 2 mass units per reduced oxo group (deuterium-hydrogen-labelling of oxo groups by reduction). Correct identification is assumed only if both mass spectral patterns fit the theory. Sample volumes of 5--100 ml of urine are needed. About six samples can be derivatized per week. Three cases with suspected peptiduria were investigated and the following peptides were found: Gly-Pro-4Hyp-Gly; Gly-Pro-4Hyp; Gly-Hyp-Hyp (postulated isomer Gly-3Hyp-4Hyp); Pro-4Hyp and Gly-Pro. With exception of the tetrapeptide, these compounds could be detected also in the urine of a healthy child. PMID:436283

  3. Overall calibration procedure via a statistically based matrix-comprehensive approach in the stir bar sorptive extraction-thermal desorption-gas chromatography-mass spectrometry analysis of pesticide residues in fruit-based soft drinks.

    PubMed

    Lavagnini, Irma; Urbani, Alessandro; Magno, Franco

    2011-02-15

    Stir bar sorptive extraction (SBSE)-thermal desorption (TD) procedure combined with gas chromatography mass spectrometry (GC-MS) and the statistical variance component model (VCM) is applied to the determination of semi-volatile compounds including organochlorine and organophosphorus pesticides in various synthetic and real fruit-based soft drink matrices. When the matrix effects are corrected using isotopically labelled or non labelled internal standard, but matrix/calibration run-induced deviations are still present in the measurements, the adoption of a variance component model (VCM) in the quantitative analysis of various matrices via an overall calibration curve is successful. The method produces an overall calibration straight line for any analyte accounting for the uncertainty due to all the sources of uncertainty, namely matrix-induced deviations, calibration runs performed at different times, measurement errors. Small increases in the detection limits and in uncertainty in the concentration values obtained in the inverse regression face favourably the decrease in times and costs for routine analyses. PMID:21238780

  4. Direct Analysis of Leucine and Its Metabolites β-Hydroxy-β-methylbutyric Acid, α-Ketoisocaproic Acid, and α-Hydroxyisocaproic Acid in Human Breast Milk by Liquid Chromatography-Mass Spectrometry.

    PubMed

    Ehling, Stefan; Reddy, Todime M

    2015-09-01

    A direct, quantitative, and confirmatory method based on stable isotope dilution liquid chromatography-mass spectrometry was developed and validated for the analysis of leucine and metabolites β-hydroxy-β-methylbutyric acid (HMB), α-ketoisocaproic acid (KIC), and α-hydroxyisocaproic acid (HICA) in human breast milk. Chromatographic resolution was achieved between isobaric leucine and isoleucine. Accuracy and intermediate precision were 89-117% and <10% relative standard deviation (RSD) across three validation runs. Limits of quantitation for HMB, KIC, HICA, and leucine in human breast milk were 20 μg/L, 20 μg/L, 10 μg/L, and 1 mg/L. Measured concentrations of HMB, KIC, HICA, and free leucine in human breast milk from six donors at various stages of lactation were 42-164 μg/L, < 20-1057 μg/L, < 10 μg/L, and 2.1-88.5 mg/L. HMB and KIC were confirmed in human breast milk by orthogonal hydrophilic interaction chromatography (HILIC). This work provides a tool for further study of human breast milk composition and its effect on protein turnover in developing infants. PMID:26271627

  5. Characterization of ballpoint pen inks by thermal and desorption and gas chromatography-mass spectrometry.

    PubMed

    Bügler, Jürgen H; Buchner, Hans; Dallmayer, Anton

    2005-09-01

    The characterization of ink on paper is of importance for dating and comparing questioned ink entries in forensic document examination. Inks are commonly characterized by their colorant profile that is identified by well-established analytical methods. Numerous ink formulations show identical colorant profiles, though. In order to differentiate inks that are not distinguishable by colorant analysis, a method for the characterization of colorless ink ingredients, namely binders, solvents and additives is necessary. In this paper, we propose a technique for the analysis of colorless compounds in ballpoint inks using direct thermal desorption of the ink on paper followed by chemical analysis of the desorbed volatile compounds by gas chromatography-mass spectrometry. As compared to liquid extraction and subsequent analysis of the extracts, the technique avoids possible contamination risks. Sensitivity is very high due to the enrichment of volatile components by thermal desorption. Even from old samples, the chromatograms obtained by the method enable the determination of binder polymers, solvents and additives. Pure binders as used by ink manufacturers were analyzed for unambiguous assignment of analytical results to specific polymers. To prove the practical applicability, we analyzed 121 ballpoint pens, not all having the same colorant profile, and grouped the pens into resin and solvent categories. PMID:16225233

  6. Laser desorption fast gas chromatography-mass spectrometry in supersonic molecular beams.

    PubMed

    Shahar, T; Dagan, S; Amirav, A

    1998-06-01

    A novel method for fast analysis is presented. It is based on laser desorption injection followed by fast gas chromatography-mass spectrometry (GC-MS) in supersonic molecular beams. The sample was placed in an open air or purged laser desorption compartment, held at atmospheric pressure and near room temperature conditions. Desorption was performed with a XeCl Excimer pulsed laser with pulse energy of typically 3 mJ on the surface. About 20 pulses at 50 Hz were applied for sample injection, resulting in about 0.4 s injection time and one or a few micrograms sample vapor or small particles. The laser desorbed sample was further thermally vaporized at a heated frit glass filter located at the fast GC inlet. Ultrafast GC separation and quantification was achieved with a 50-cm-long megabore column operated with a high carrier gas flow rate of up to 240 mL/min. The high carrier gas flow rate provided effective and efficient entrainment of the laser desorbed species in the sweeping gas. Following the fast GC separation, the sample was analyzed by mass spectrometry in supersonic molecular beams. Both electron ionization and hyperthermal surface ionization were employed for enhanced selectivity and sensitivity. Typical laser desorption analysis time was under 10 s. The laser desorption fast GC-MS was studied and demonstrated with the following sample/matrices combinations, all without sample preparation or extraction: (a) traces of dioctylphthalate plasticizer oil on stainless steel surface and the efficiency of its cleaning; (b) the detection of methylparathion and aldicarb pesticides on orange leaves; (c) water surface analysis for the presence of methylparathion pesticide; (d) caffeine analysis in regular and decaffeinated coffee powder; (e) paracetamol and codeine drug analysis in pain relieving drug tablets; (f) caffeine trace analysis in raw urine; (g) blood analysis for the presence of 1 ppm lidocaine drug. The features and advantages of the laser desorption fast GC-MS are demonstrated and discussed. PMID:9879375

  7. Impurity profiling of trinitrotoluene using vacuum-outlet gas chromatography-mass spectrometry.

    PubMed

    Brust, Hanneke; Willemse, Sander; Zeng, Tuoyu; van Asten, Arian; Koeberg, Mattijs; van der Heijden, Antoine; Bolck, Annabel; Schoenmakers, Peter

    2014-12-29

    In this work, a reliable and robust vacuum-outlet gas chromatography-mass spectrometry (GC-MS) method is introduced for the identification and quantification of impurities in trinitrotoluene (TNT). Vacuum-outlet GC-MS allows for short analysis times; the analysis of impurities in TNT was performed in 4min. This study shows that impurity profiling of TNT can be used to investigate relations between TNT samples encountered in forensic casework. A wide variety of TNT samples were analyzed with the developed method. Dinitrobenzene, dinitrotoluene, trinitrotoluene and amino-dinitrotoluene isomers were detected at very low levels (<1wt.%) by applying the MS in selected-ion monitoring (SIM) mode. Limits of detection ranged from 6ng/mL for 2,6-dinitrotoluene to 43ng/mL for 4-amino-2,6-dinitrotoluene. Major impurities in TNT were 2,4-dinitrotoluene and 2,3,4-trinitrotoluene. Impurity profiles based on seven compounds showed to be useful to TNT samples from different sources. Statistical analysis of these impurity profiles using likelihood ratios demonstrated the potential to investigate whether two questioned TNT samples encountered in forensic casework are from the same source. PMID:25488253

  8. Development of a technique for mercury speciation and quantification using gas chromatography/mass spectrometry

    SciTech Connect

    Barshick, S.A.; Barshick, C.M.; Britt, P.F.; Vance, M.A.; Duckworth, D.C.

    1997-07-01

    One element of concern to DOE is mercury. Mercury was used extensively at the DOE facilities in Oak Ridge, Tennessee from 1950 to 1963 in the process of making lithium deuteride, a component of nuclear weapons. Although both the inorganic and organometallic forms of mercury are toxic to humans, the organic compounds are often more toxic. Since the toxicity of mercury is a function of its chemical form, an understanding of the interactions between commercially discharged mercury, naturally occurring mercury, and the environment in which they are present is vital. In this report, the authors have been investigating gas chromatography/mass spectrometry (GC/MS) for the analysis of both the organometallic and inorganic forms of mercury in the same environmental sample (e.g., solutions, soils, and sludges). Although gas chromatography is the classical technique for analyzing organic molecules, (e.g., organometallic compounds) little has been done on the analysis of inorganic compounds. In a previous publication, the authors described how a solid phase microextraction (SPME) fiber could be used to sample organomercurials from aqueous samples. An alkylation reaction was then carried out to transform chemically mercury nitrate into dimethylmercury; subsequent GC/MS analysis of this compound permitted quantification of the inorganic constituent. Subsequently, several different alkylation reagents have been synthesized that methylate any inorganic mercury compound to methylmercury iodide. Here, the authors report results on alkylation reaction time and the effect of pH on the population of the product.

  9. Analysis of polycyclic aromatic hydrocarbons in pine needles by gas chromatography-mass spectrometry: comparison of different extraction and clean-up procedures.

    PubMed

    Ratola, Nuno; Lacorte, Sílvia; Alves, Arminda; Barceló, Damià

    2006-05-12

    Three extraction methodologies (Soxhlet, ultrasonic and pressurized liquid extraction) and several clean-up procedures (Florisil, silica and alumina in cartridges or glass column format) were tested and compared to extract 16 US Environmental Protection Agency (EPA) polycyclic aromatic hydrocarbons (PAHs) from Pinus pinea L. needles. Quantification was done by gas chromatography with mass spectrometry, by internal standard method using five deuterated PAH surrogate standards. Among the several extraction and clean-up procedures tested, ultrasonic extraction followed by alumina cartridge clean-up was the preferred method, yielding recoveries between 72 and 100% and limits of detection between 0.22 and 0.71 ng/g dry weight. The performance of the method was tested to determine PAHs in naturally contaminated samples. PMID:16620846

  10. The determination of underivatized chlorophenols in human urine by combined high performance liquid chromatography mass spectrometry and selected ion monitoring.

    PubMed

    Wright, L H; Edgerton, T R; Arbes, S J; Lores, E M

    1981-10-01

    A method for the determination of underivatized chlorophenols in human urine samples by combined high performance liquid chromatography mass spectrometry is described. Results obtained on individual samples are reported and compared with data obtained by alternative chromatographic methods. PMID:7295873

  11. EIder: A compound identification tool for gas chromatography mass spectrometry data.

    PubMed

    Koo, Imhoi; Kim, Seongho; Shi, Biyun; Lorkiewicz, Pawel; Song, Ming; McClain, Craig; Zhang, Xiang

    2016-05-27

    We report software entitled EIder (EI mass spectrum identifier) that provides users with eight literature reported spectrum matching algorithms for compound identification from gas chromatography mass spectrometry (GC-MS) data. EIder calculates retention index according to experimental conditions categorized by column class, column type and data type, where 9 empirical distribution functions of the absolute retention index deviation to its mean value were constructed using the National Institute of Standards and Technology (NIST) 2011 retention index database to improve the accuracy of compound identification. EIder filters compound candidates based on elementary composition and derivatization reagent, and automatically adds the molecular information of the native compound to each derivatized compound using a manually created database. When multiple samples are analyzed together, EIder performs cross-sample alignment and provides an option of using an average mass spectrum for compound identification. Furthermore, a suite of graphical user interfaces are implemented in EIder to allow users to both manually and automatically modify the identification results using experimental information at various analysis stages. Analysis of three types of GC-MS datasets indicates that the developed EIder software can improve the accuracy of compound identification. PMID:27131963

  12. Toward automated chromatographic fingerprinting: A non-alignment approach to gas chromatography mass spectrometry data.

    PubMed

    Vestner, Jochen; de Revel, Gilles; Krieger-Weber, Sibylle; Rauhut, Doris; du Toit, Maret; de Villiers, André

    2016-03-10

    In contrast to targeted analysis of volatile compounds, non-targeted approaches take information of known and unknown compounds into account, are inherently more comprehensive and give a more holistic representation of the sample composition. Although several non-targeted approaches have been developed, there's still a demand for automated data processing tools, especially for complex multi-way data such as chromatographic data obtained from multichannel detectors. This work was therefore aimed at developing a data processing procedure for gas chromatography mass spectrometry (GC-MS) data obtained from non-targeted analysis of volatile compounds. The developed approach uses basic matrix manipulation of segmented GC-MS chromatograms and PARAFAC multi-way modelling. The approach takes retention time shifts and peak shape deformations between samples into account and can be done with the freely available N-way toolbox for MATLAB. A demonstration of the new fingerprinting approach is presented using an artificial GC-MS data set and an experimental full-scan GC-MS data set obtained for a set of experimental wines. PMID:26893085

  13. Identification of floral scent in chrysanthemum cultivars and wild relatives by gas chromatography-mass spectrometry.

    PubMed

    Sun, Hainan; Zhang, Ting; Fan, Qingqing; Qi, Xiangyu; Zhang, Fei; Fang, Weimin; Jiang, Jiafu; Chen, Fadi; Chen, Sumei

    2015-01-01

    The objective of this study was to identify the major volatile compounds and their relative concentrations in flowers of different chrysanthemum cultivars and their wild relatives. The volatile organic components of fresh flowers were analyzed using a headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry. In total, 193 volatile organic components were detected; the major scent components were monoterpenoids and oxygenated monoterpenoids, which accounted for 68.59%-99.93% of the total volatiles in all tested materials except for Chrysanthemum indicum collected from Huangshan, in which they accounted for only 37.45% of total volatiles. The major volatile compounds were camphor, α-pinene, chrysanthenone, safranal, myrcene, eucalyptol, 2,4,5,6,7,7ab-hexahydro-1H-indene, verbenone, β-phellandrene and camphene. In a hierarchical cluster analysis, 39 accessions of Chrysanthemum and its relatives formed six clusters based on their floral volatile compounds. In a principal component analysis, only spider type flowers were located closely on the score plot. The results of this study provide a basis for breeding chrysanthemum cultivars which desirable floral scents. PMID:25816078

  14. Detection of methamphetamine and its main metabolite in fingermarks by liquid chromatography-mass spectrometry.

    PubMed

    Zhang, Ting; Chen, Xueguo; Yang, Ruiqin; Xu, Yingjian

    2015-03-01

    A sensitive and efficient method applying liquid chromatography-mass spectrometry for the analysis of methamphetamine and its main metabolite in fingermark deposits was described. Using this method, good linear relationship of methamphetamine was obtained in the range of 0.005μg to 0.5μg per cotton swab, the limit of detection was 1.5ng per cotton swab, the limit of quantitation was 5.0ng per cotton swab and the average values of recovery ratios were above 70.1%. Moreover, the influence factors for the detection of methamphetamine in fingermarks, such as kinds of substrates, development methods and extraction methods, were all discussed in details. The results showed that good recovery ratios could be obtained on painted wood and smooth substrates surfaces. Development methods in commercial powder could not influence the quality of examination of exogenous drug in latent fingermark. Furthermore, the results indicated that the method mentioned here could be applied in the analysis of forensic trace evidences and samples obtained in clinically addicted cases. PMID:25576675

  15. 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

  16. Structural identification of petroleum acids by conversion to hydrocarbons and multidimensional gas chromatography-mass spectrometry.

    PubMed

    Wilde, Michael J; Rowland, Steven J

    2015-08-18

    Identification of individual petroleum acids ("naphthenic" acids, NA) has proved challenging for decades, due to the extreme complexity of many petroleum acid mixtures. This has hindered detailed understanding of the role of NA in petroleum generation and oil production processes, refinery corrosion, as wood preservatives, and as environmental toxicants. Some recent advances have been made due to improved chromatographic separation of esters of the acids by multidimensional gas chromatography-mass spectrometry (GC × GC-MS), but relatively few reference spectra of esters are available for comparison. Here we report a complementary method based on a combination of a modified historical approach of converting NA to the corresponding hydrocarbons, followed by analysis by GC × GC-MS. Many published spectra exist for reference hydrocarbons making comparisons of reference spectra with those of the unknowns, much more feasible. As an example, we report identification of over 30 individual bicyclic naphthenic acids as the bicyclane hydrocarbons. These include both fused and bridged acids possessing methyl, dimethyl, and ethyl alkyl substituents as well as some terpenoid-derived acids. The study provides the most comprehensive analysis of one of the major classes of NA (the bicyclic acids) to date. There is now clear potential for this method to be used for the structural elucidation of other unknown acids (e.g., oil sands acids) and functionalized biomarkers in complex mixtures. PMID:26171636

  17. 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

  18. 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

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

    PubMed

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

    1994-11-01

    An automated environmental air monitor has been developed to measure selected organic compounds in urban air. The instrument is based on a cryofocusing-thermal desorption gas chromatographic mass spectrometry technique where the mass spectrometer is a slightly modified residual gas analyzer (RGA). The RGA was chosen as a detector because the whole system must be robust for long periods, with 24-h continuous air monitoring. RCA are extremely simple and seemed the most reliable mass spectrometers for this purpose. Moreover, because they have no physically limited ion source, contamination is considerably reduced, so maintenance intervals are longer.The gas chromatograph is equipped with a computer-controlled six-way sampling valve, with a 100-mL sampling loop and thermal desorption cold trap injector. Environmental air is enriched with an isotopically labeled internal standard in the sampling line. This internal standard is added with a validated, custom-made, permeation tube device. The "on-line" internal standard provides for high quality quantitative data because all variations in instrument sensitivity in cryofocusing or in thermal desorption efficiency are taken into account. High repetition rates (down to 5 min for a full analytical cycle) are obtained with the use of an isothermal gas chromatography program, microbore capillary column, and environmental air sampling during the gas chromatography run. PMID:24226389

  20. Multi-class method for biomonitoring of hair samples using gas chromatography-mass spectrometry.

    PubMed

    Martín, Julia; Möder, Monika; Gaudl, Alexander; Alonso, Esteban; Reemtsma, Thorsten

    2015-11-01

    Currently, non-invasive biomonitoring of human exposure to organic pollutants bases upon the analysis mainly of urine and human breast milk. While mostly persistent organic pollutants are the center of interest, the aim of our study was to develop a method for the determination of different chemical classes of emerging pollutants (organophosphorus flame retardants, plastic additives such as phthalates, bisphenol A, insecticides, antimicrobials, preservatives and musk fragrances) in hair by gas chromatography-mass spectrometry. The preferred sample preparation included hydrolysis of the hair with trifluoroacetic acid in methanol followed by a liquid-liquid extraction using hexane/ethyl acetate. The validated method is characterized by recoveries higher than 77 % for most analytes, relative standard deviations below 16 % and limits of detection between 2 pg mg(-1) (HHCB) and 292 pg mg(-1) (propylparaben) using 50 mg of dry hair. After respective blank corrections, bis-(2-ethylhexyl)phthalate (DEHP) and the musk fragrance HHCB were the predominant compounds determined in all hair samples at concentrations between 32 and 59 ng mg(-1) and 0.8-13 ng mg(-1), respectively. The bactericide triclosan and the insect repellent N,N-diethyl-3-methylbenzamide (DEET) were detected in selected hair samples at 2 and 0.8 ng mg(-1), respectively. PMID:26427497

  1. Oxidative degradation of polysorbate surfactants studied by liquid chromatography-mass spectrometry.

    PubMed

    Borisov, Oleg V; Ji, Junyan A; Wang, Y John

    2015-03-01

    Polysorbates (PSs), as acquired from manufacturing processes and chemical nature of fatty acids (FAs) used in production of biotherapeutic formulations, are heterogeneous mixtures of structurally related compounds, covering a wide range of physicochemical properties. Such complexity presents a certain challenge for analysis of these important surfactants and demands the use of methods offering sufficient resolution to monitor individual classes of species and detect changes upon stress. A liquid chromatography mass spectrometry method, benefiting from the use of low m/z marker ions, simplifies profiling of PSs by providing detailed information on FA composition even of chromatographically overlapping peaks. The ability of the method to monitor individual components and follow their changes because of oxidative stress was explored. A water-soluble azo compound was used as a model oxidizer. Major degradation products of PS 80, because of reactions involving double bond, were identified as oxo-C9:0, keto-C18:1, hydroxyl-C18:1, epoxy-C18:0, and hydroperoxy-C18:1. Stability of PS 20 components was found to depend on the carbon number of polyethoxylated (POE) sorbitan FA ester and its order. Rates of oxidative degradation increased with the length of the FA ester and, moreover, POE sorbitan diesters degraded significantly faster in comparison to the corresponding monoesters upon the oxidative stress. PMID:25581232

  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. 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

  4. Determination of cyclamate in urine by derivatized gas chromatography-mass spectrometry

    PubMed Central

    Idris, Mohd; Middha, Deepak; Rasool, Shaik N.; Shukla, Sudhir K.; Baggi, Tulsidas R.

    2013-01-01

    Aim: It is important in toxicological/drug screening work to rule out the possible interfering analytes, to eliminate the false positive or negative results. In this paper, we describe a simple, selective, and sensitive derivatized GC-MS method for the determination of cyclohexylsulfamic acid (cyclamate) in urine. Materials and Methods: Elite- 5MS capillary column was used for the separation of analytes and detection using GC-MS. The analysis was carried out in selected ion monitoring mode (SIM) in the range of 26 to 200 using m/z values of 57, 30, 55, 41, 44, 67, 82, 98, and 39. Results and Discussion: The method is based on the conversion of cyclamate into nitroso derivative of cyclamate followed by its gas chromatography-mass spectrometry determination. The limit of detection, limit of quantitation, and linearity range of the proposed method were found to be 0.2 μg/ ml, 0.7 μg/ml, and 1-15 μg/ml, respectively. The recovery of the present method is in the range of 88-94%. Conclusion: The proposed method can be applied for detection and quantification of cyclamate in urine. PMID:23559823

  5. Metabolomic profiling in inner ear fluid by gas chromatography/mass spectrometry in guinea pig cochlea.

    PubMed

    Fujita, Takeshi; Yamashita, Daisuke; Irino, Yasuhiro; Kitamoto, Junko; Fukuda, Yuriko; Inokuchi, Go; Hasegawa, Shingo; Otsuki, Naoki; Yoshida, Masaru; Nibu, Ken-ichi

    2015-10-01

    The composition and homeostasis of inner ear fluids are important in hearing function. The purpose of this study was to perform metabolomic analysis of the inner ear fluid in guinea pig cochlea, which has not been previously reported in literature, using gas chromatography/mass spectrometry (GC/MS). Seventy-seven kinds of metabolites were detected in the inner ear fluid. Six metabolites, ascorbic acid, fructose, galactosamine, inositol, pyruvate+oxaloacetic acid, and meso-erythritol, were significantly more abundant, and nine metabolites, phosphate, valine, glycine, glycerol, ornithine, glucose, citric acid+isocitric acid, mannose, and trans-4-hydroxy-L-proline, were less abundant in the inner ear fluid than in plasma. The levels of ten metabolites, 3-hydroxy-butyrate, glycerol, fumaric acid, galactosamine, pyruvate+oxaloacetic acid, phosphate, meso-erythritol, citric acid+isocitric acid, mannose, and inositol, in the inner ear fluid significantly changed after loud noise exposure. These observations may help to elucidate various clinical conditions of sensorineural hearing loss, including noise-induced hearing loss. PMID:26343935

  6. Study on volatile components in salami by reverse carrier gas headspace gas chromatography-mass spectrometry.

    PubMed

    Procida, G; Conte, L S; Fiorasi, S; Comi, G; Favretto, L G

    1999-01-01

    Salami are a typical seasoned sausage of Italy; a number of types are produced, according to local traditional recipes. As industrial production has taken place, a number of problems rise in obtaining products similar to the traditional ones. The use of selected microbial starters is permitted by Italian law for some years and at present, microbiological research is engaged in selecting starters similar to the ones isolated from traditional products, with the aim of obtaining organoleptic characteristics close to the ones of traditional recipes. A study was carried out concerning the characterisation of volatile components of salami by headspace capillary gas chromatography-mass spectrometry. As during the sampling step, analytes could reach the analytical column, the carrier gas rate was back flushed in the latter, while a pre column was used as cold trap. Then GC-MS analysis follows. By these techniques, we were able to highlight typical profiles of different salami, as well as monitoring the ripening of a traditional and a starter added salami. Main peaks are of fermentative origin, while also peaks from spices were detected. Ethyl propionate was used as internal standard to be able to normalise the peaks amounts. PMID:10023625

  7. Evaluation of the quality of sandalwood essential oils by gas chromatography-mass spectrometry.

    PubMed

    Howes, Melanie-Jayne R; Simmonds, Monique S J; Kite, Geoffrey C

    2004-03-01

    Trade and historic oils from 'sandalwoods', labelled as Amyris balsamifera, Eremophila mitchelli, Fusanus acuminatus (= Santalum acuminatum), Santalum album, S. austrocaledonicum, S. latifolium, S. spicatum and S. yasi, were assessed using gas chromatography-mass spectrometry (GC-MS). Using GC-MS, none of the oils assessed complied with the internationally recognised standard of a 90% santalol content, and only about half of the trade sandalwood oils met with recent International Organisation for Standardisation standards. The majority of trade oils, reportedly from S. album, contained approximately 50-70% santalols (Z-alpha and Z-beta). Thus, the internationally recognised specification (90% santalols) for S. album requires re-evaluation by more efficient analysis methods. In view of the issues associated with the quality of sandalwood oils being traded, specifications of > or = 43% Z-alpha-santalol and > or = 18% Z-beta-santalol for S. album oil estimated by GC-MS are suggested. GC-MS are recommended as it assists with authentication and quality control issues associated with sandalwood oils. PMID:14989484

  8. [Comparison of metabolite extraction from Boea hygrometrica by gas chromatography/mass spectrometry].

    PubMed

    Zhang, Xiaofei; Duan, Lixin; Gong, Yuehua; Deng, Xin

    2014-02-01

    This study is aiming to establish an efficient metabolite extraction method for exploration of molecular mechanisms of desiccation tolerance of the resurrection plant Boea hygrometrica using a metabolomics approach. The extracts of metabolite in B. hygrometrica using methanol solution (method A) and methanol-chloroform-water solution (method B) were analyzed by gas chromatography-mass spectrometry (GC-MS). The total numbers of chromatographic peaks, extraction efficiency, retention time and the peak stability were compared. The results showed that for fresh materials, the total chromatographic peak number of method B is more than that of method A; the extraction efficiency of nine representative metabolites by method B is higher than that by method A; the comparison of 10 random chromatographic peaks revealed that the relative standard deviation (RSD) values of the retention time are less than 1% for both methods, whereas the RSD values of the extraction efficiency is different. The percentage of peaks that owned RSD values of the extraction efficiency higher than 10% is 50% for method A and 100% for method B. In addition, method B was also efficient for dry materials from B. hygrometrica. The number of chromatographic peaks, RSD value of retention time and extraction efficiency of dry materials was similar to that of fresh materials using method B, but decreased sharply using method A. Putting together, our study provided evidence that method B is an efficient extraction method for further analysis of metabolites from this resurrection species. PMID:24941750

  9. Compound Identification Using Partial and Semi-partial Correlations for Gas Chromatography Mass Spectrometry Data

    PubMed Central

    Kim, Seongho; Koo, Imhoi; Jeong, Jaesik; Wu, Shiwen; Shi, Xue; Zhang, Xiang

    2012-01-01

    Compound identification is a key component of data analysis in the applications of gas chromatographymass spectrometry (GC-MS). Currently, the most widely used compound identification is mass spectrum matching, in which dot product and its composite version are employed as spectral similarity measures. Several forms of transformations for fragment ion intensities have also been proposed to increase the accuracy of compound identification. In this study, we introduced partial and semi-partial correlations as mass spectral similarity measures and applied them to identify compounds along with different transformations of peak intensity. The mixture versions of the proposed method were also developed to further improve the accuracy of compound identification. To demonstrate the performance of the proposed spectral similarity measures, the National Institute of Standard Technology (NIST) mass spectral library and replicate spectral library were used as the reference library and the query spectra, respectively. Identification results showed that the mixture partial and semi-partial correlations always outperform both the dot-product and its composite measure. The mixture similarity with semi-partial correlation has the highest accuracy of 84.6% in compound identification with a transformation of (0.53, 1.3) for fragment ion intensity and m/z value, respectively. PMID:22794294

  10. Metabolic products in urine of preterm infants characterized via gas chromatography-mass spectrometry

    PubMed Central

    Hao, Hu; Li, Sitao; Zhou, Wei; Wang, Hong; Liu, Mengxian; Shi, Congcong; Chen, Jing; Xiao, Xin

    2015-01-01

    Objective: To characterize the metabolic products of urine associated with preterm birth, thus providing clinical guidelines for intestinal and parenteral nutrition in preterm infants. Methods: Urine samples of 47 preterm infants and 45 full-term infants were collected and prepared for trimethylsilylation by treatment with urease. The levels of lysine, phenylalanine, histidine, ornithine, fumaric acid, malic acid, succinic acid, lactose, stearic acid, and 4-hydroxyphenylacetic acid were detected by gas chromatography-mass spectrometry (GC/MS), and statistically analyzed. Results: The normalized concentrations of the following metabolites in preterm infant urine samples were significantly lower than that of full-term infant urine samples: lysine (P = 0.003), phenylalanine (P = 0.001), histidine (P = 0.006), ornithine (P = 0.000), fumaric acid (P = 0.002), malic acid (P = 0.006), succinic acid (P = 0.000), lactose (P = 0.000), stearic acid (P = 0.000) and 4-hydroxyphenylacetic acid (P = 0.000). Conclusions: The results of the GC/MS analysis indicated that amino acid, carbohydrate, and fatty acid metabolism defects exist in preterm infants. The use of GC/MS to determine metabolic products in urine samples could be helpful for prospectively evaluating the nutritional status of preterm infants, and therefore providing clinical guidelines on reasonable nutritional support. PMID:26629171

  11. Identification of the aromatase inhibitor letrozole in urine by gas chromatography/mass spectrometry.

    PubMed

    Mareck, U; Sigmund, G; Opfermann, G; Geyer, H; Thevis, M; Schänzer, W

    2005-01-01

    Letrozole (1-(bis-(4-cyanophenyl)methyl)-1,2,4-triazole) is used therapeutically as a non-steroidal aromatase inhibitor (Femara) to treat hormone-sensitive breast cancer in postmenopausal women. For doping purposes it may be used to counteract the adverse effects of an extensive abuse of anabolic androgenic steroids (gynaecomastia) and to increase the testosterone concentration by stimulation of the testosterone biosynthesis. The use of aromatase inhibitors has been prohibited by IOC/WADA regulations for male and female athletes since September 2001 and January 2005, respectively. Spot urine samples from women suffering from metastatic breast cancer and being treated with letrozole were collected and analysed to develop/optimise the detection system for metabolites of letrozole to allow the identification of athletes who do not comply with the internationally prohibited use of this cancer drug. The assay was based on gas chromatography/mass spectrometry (GC/MS) and the main metabolite of letrozole (bis-4-cyanophenylmethanol) was identified by comparison of its mass spectrum and retention time with that of a bis-4-cyanophenylmethanol reference. The full-scan spectrum, diagnostic ions and a validation of the method for the analysis of bis-4-cyanophenylmethanol are presented. PMID:16299697

  12. COMPUTER SURVEY OF GC/MS (GAS CHROMATOGRAPHY/MASS SPECTROMETRY) DATA ACQUIRED IN EPA'S (ENVIRONMENTAL PROTECTION AGENCY) PRIORITY POLLUTANT SCREENING ANALYSIS: SYSTEM AND RESULTS

    EPA Science Inventory

    The screening analysis phase of the best available treatment (BAT) review of wastewater treatment techniques by EPA was initiated to assess 21 industrial categories for the 129 'priority pollutants.' Implicit in the purpose of the screening analysis for these pollutants was the n...

  13. Chemometric analysis of urine fingerprints acquired by liquid chromatography-mass spectrometry and capillary electrophoresis: application to the schistosomiasis mouse model.

    PubMed

    Garcia-Perez, Isabel; Earll, Marc E; Angulo, Santiago; Barbas, Coral; Legido-Quigley, Cristina

    2010-07-01

    Urine fingerprints from Schistosoma mansoni infected and control animals were acquired with ultra performance liquid chromatography-MS (UPLC-MS) and compared with the urine fingerprints obtained by CE by applying the same set of multivariate analysis tools. Principal component analysis of the aligned data provided a time trajectory where the infection was observed after 30 days with UPLC-MS and CE. Two main markers describing infected and control, respectively - phenyl acetyl glycine (PAG) and hippurate - were selected to illustrate the use of orthogonal partial least-square discriminant analysis in determining the discriminatory confidence. PAG was found to be significantly related to the disease (high covariance and correlation), whereas hippurate was found to be nonsignificant as an indicator. Orthogonal partial least-square discriminant analysis models were validated for sensitivity and specificity. Multivariate data analysis derived from two different detection systems showed that CE-UV and UPLC-MS found equivalent results. This work gives additional mechanistic insight into the progress of the S. mansoni infection; the biochemical role and specificity of PAG as a biomarker is yet to be determined. PMID:20575107

  14. Extract-filter-shoot liquid chromatography/mass spectrometry for analysis of vitamin D2 in a powdered supplement capsule and SRM 3280

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An ‘extract-filter-shoot’ method for analysis of vitamin D2, ergocalciferol, in a dry powdered dietary supplement capsule containing rice flour excipient and in National Institute of Standards and Technology (NIST) standard reference material (SRM) 3280 is reported. Quantification of vitamin D2 was...

  15. On-line analysis of volatile chlorinated hydrocarbons in air by gas chromatography-mass spectrometry Improvements in preconcentration and injection steps.

    PubMed

    Zoccolillo, Lelio; Amendola, Luca; Insogna, Susanna; Pastorini, Elisabetta

    2010-06-11

    An analytical system composed of a cryofocusing trap injector device coupled to a gas chromatograph with mass spectrometric detection (CTI-GC-MS) specific for the on-line analysis in air of volatile chlorinated hydrocarbons (VCHCs) (dichloromethane; chloroform; 1,1,1-trichloroethane; tetrachloromethane; 1,1,2-trichloroethylene; tetrachloroethylene) was developed. The cryofocusing trap injector was the result of appropriate low cost modifications to an original purge-and-trap device to make it suitable for direct air analysis even in the case of only slightly contaminated air samples, such as those from remote zones. The CTI device can rapidly and easily be rearranged into the purge-and-trap allowing water and air analysis with the same apparatus. Air samples, collected in stainless steel canisters, were introduced directly into the CTI-GC-MS system to realize cryo-concentration (at -120 degrees C), thermal desorption (at 200 degrees C) and for the subsequent analysis of volatiles. The operating phases and conditions were customised and optimized. Recovery efficiency was optimized in terms of moisture removal, cold trap temperature and sampling mass flow. The injection of entrapped volatiles was realized through a direct transfer with high chromatographic reliability (capillary column-capillary column). These improvements allowed obtaining limits of detection (LODs) at least one order of magnitude lower than current LODs for the investigated substances. The method was successfully employed on real samples: air from urban and rural areas and air from remote zones such as Antarctica. PMID:20444461

  16. 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

  17. Effect of process conditions on the analysis of free and conjugated estrogen hormones by solid-phase extraction-gas chromatography/mass spectrometry (SPE-GC/MS).

    PubMed

    Suri, Rominder P S; Singh, Tony Sarvinder; Chimchirian, Robert F

    2012-03-01

    Simultaneous analysis of 11 free estrogen hormones and five conjugated estrogens in water and municipal wastewater was studied. The analytical method was developed and tested for different types of solid-phase extraction adsorbents, eluents, sample containers and storage conditions, derivatization, and matrix effects. Varian Bond Elut C-18 solid-phase extraction adsorbent cartridge was selected based on its high recoveries for both free and conjugated estrogens. Sample storage conditions, as well as selection and pretreatment of sample container materials, can affect the trace level analysis of estrogens. Silanization of glassware is observed to provide low relative standard deviation (RSD) in the analysis and less percentage loss due to contacting with sample container materials. Light exposure during the test can significantly impact the results. The derivatized samples stored at -20°C for at least 6 days showed less than 10.5% average RSD in the analysis. The recovery efficiency in clean water varies from 72% to 101% for free estrogens and 78% to 82% for conjugated estrogens. The method detection limits (MDL) for most of the compounds range from 30 to 870 ng/L using a sample volume of 200 mL. With a sample volume of 3 L, the most sensitive compound produces a MDL of 0.03 ng/L. Dilute methanol is used to wash the loaded cartridge as a cleanup step in order to remove interfering species during analysis of wastewater samples. Using the optimized analytical methods, the concentration level of free estrogens in the influent and effluent municipal wastewaters is tested. PMID:21544501

  18. 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

  19. Analysis of French and American oak chips with different toasting degrees by headspace solid-phase microextraction-gas chromatography-mass spectrometry.

    PubMed

    Bozalongo, Ruth; Carrillo, José David; Torroba, Miguel Angel Fernández; Tena, María Teresa

    2007-11-30

    This paper describes the optimisation of headspace solid-phase microextraction (HS-SPME) conditions for the analysis of volatile compounds in oak chips used to accelerate wine aging as an alternative to traditional aging in oak barrels. The direct extraction of ground wood samples and the extraction of sample aqueous slurries using a divinylbenzene-carboxen-polydimethylsiloxane (DVB-CAR-PDMS) fibre were studied and compared. Optimal conditions for direct extraction were 110 degrees C and 60 min, whereas for aqueous slurries they were obtained by adding 2mL of a 7.1 molL(-1) sodium chloride solution, at 70 degrees C and for 60 min. The two optimised HS-SPME approaches were compared in terms of repeatability and extraction efficiency; water addition to the sample prior to HS-SPME was selected because it yielded better repeatability (6.6% versus 8.5% relative standard deviation) and efficiency (around 1.4-4.8 times higher analyte amount extracted for most of the compounds). Finally, the method was applied in the analysis of oak chip samples from American and French oak with different degrees of toasting. Principal component analysis (PCA) of the results showed that the first principal component was correlated with the toasting degree whereas the second, which was strongly influenced by whisky lactones and eugenol, allowed us to differentiate between American and French oak chips. PMID:17964587

  20. Analysis of Serum Metabolic Profile by Ultra-performance Liquid Chromatography-mass Spectrometry for Biomarkers Discovery: Application in a Pilot Study to Discriminate Patients with Tuberculosis

    PubMed Central

    Feng, Shuang; Du, Yan-Qing; Zhang, Li; Zhang, Lei; Feng, Ran-Ran; Liu, Shu-Ye

    2015-01-01

    Background: Tuberculosis (TB) is a chronic wasting inflammatory disease characterized by multisystem involvement, which can cause metabolic derangements in afflicted patients. Metabolic signatures have been exploited in the study of several diseases. However, the serum that is successfully used in TB diagnosis on the basis of metabolic profiling is not by much. Methods: Orthogonal partial least-squares discriminant analysis was capable of distinguishing TB patients from both healthy subjects and patients with conditions other than TB. Therefore, TB-specific metabolic profiling was established. Clusters of potential biomarkers for differentiating TB active from non-TB diseases were identified using Mann–Whitney U-test. Multiple logistic regression analysis of metabolites was calculated to determine the suitable biomarker group that allows the efficient differentiation of patients with TB active from the control subjects. Results: From among 271 participants, 12 metabolites were found to contribute to the distinction between the TB active group and the control groups. These metabolites were mainly involved in the metabolic pathways of the following three biomolecules: Fatty acids, amino acids, and lipids. The receiver operating characteristic curves of 3D, 7D, and 11D-phytanic acid, behenic acid, and threoninyl-γ-glutamate exhibited excellent efficiency with area under the curve (AUC) values of 0.904 (95% confidence interval [CI]: 0863–0.944), 0.93 (95% CI: 0.893–0.966), and 0.964 (95% CI: 00.941–0.988), respectively. The largest and smallest resulting AUCs were 0.964 and 0.720, indicating that these biomarkers may be involved in the disease mechanisms. The combination of lysophosphatidylcholine (18:0), behenic acid, threoninyl-γ-glutamate, and presqualene diphosphate was used to represent the most suitable biomarker group for the differentiation of patients with TB active from the control subjects, with an AUC value of 0.991. Conclusion: The metabolic analysis results identified new serum biomarkers that can distinguish TB from non-TB diseases. The metabolomics-based analysis provides specific insights into the biology of TB and may offer new avenues for TB diagnosis. PMID:25591556

  1. Development of a dynamic headspace gas chromatography-mass spectrometry method for on-site analysis of sulfur mustard degradation products in sediments.

    PubMed

    Magnusson, R; Nordlander, T; Östin, A

    2016-01-15

    Sampling teams performing work at sea in areas where chemical munitions may have been dumped require rapid and reliable analytical methods for verifying sulfur mustard leakage from suspected objects. Here we present such an on-site analysis method based on dynamic headspace GC-MS for analysis of five cyclic sulfur mustard degradation products that have previously been detected in sediments from chemical weapon dumping sites: 1,4-oxathiane, 1,3-dithiolane, 1,4-dithiane, 1,4,5-oxadithiephane, and 1,2,5-trithiephane. An experimental design involving authentic Baltic Sea sediments spiked with the target analytes was used to develop an optimized protocol for sample preparation, headspace extraction and analysis that afforded recoveries of up to 60-90%. The optimized method needs no organic solvents, uses only two grams of sediment on a dry weight basis and involves a unique sample presentation whereby sediment is spread uniformly as a thin layer inside the walls of a glass headspace vial. The method showed good linearity for analyte concentrations of 5-200 ng/g dw, good repeatability, and acceptable carry-over. The method's limits of detection for spiked sediment samples ranged from 2.5 to 11 μg/kg dw, with matrix interference being the main limiting factor. The instrumental detection limits were one to two orders of magnitude lower. Full-scan GC-MS analysis enabled the use of automated mass spectral deconvolution for rapid identification of target analytes. Using this approach, analytes could be identified in spiked sediment samples at concentrations down to 13-65 μg/kg dw. On-site validation experiments conducted aboard the research vessel R/V Oceania demonstrated the method's practical applicability, enabling the successful identification of four cyclic sulfur mustard degradation products at concentrations of 15-308μg/kg in sediments immediately after being collected near a wreck at the Bornholm Deep dumpsite in the Baltic Sea. PMID:26711154

  2. Simple and rapid analysis for quantitation of the most important volatile flavor compounds in yogurt by headspace gas chromatography-mass spectrometry.

    PubMed

    Alonso, L; Fraga, M J

    2001-07-01

    The aim of this experiment is to develop a rapid, simplified, direct gas chromatographic (GC) method for the analysis of volatile flavor compounds in yogurt combining a headspace with constant heating temperature and GC with a mass spectrometric detect ion. Repeatability of the method is assessed. The relative standard deviation for individual flavor compounds range from 3.5% for acetaldehyde to 8.4% for acetone, with a total mean value of 52.4 +/- 2.2 mg/kg for all of the studied aroma components. Recovery for individual flavor compounds range from 63.7% for acetone to 82.4% for acetic acid. PMID:11471993

  3. Focused microwave-assisted extraction combined with solid-phase microextraction and gas chromatography-mass spectrometry for the selective analysis of cocaine from coca leaves.

    PubMed

    Bieri, Stefan; Ilias, Yara; Bicchi, Carlo; Veuthey, Jean-Luc; Christen, Philippe

    2006-04-21

    An effective combination of focused microwave-assisted extraction (FMAE) with solid-phase microextraction (SPME) prior to gas chromatography (GC) is described for the selective extraction and quantitative analysis of cocaine from coca leaves (Erythroxylum coca). This approach required switching from an organic extraction solvent to an aqueous medium more compatible with SPME liquid sampling. SPME was performed in the direct immersion mode with a universal 100 microm polydimethylsiloxane (PDMS) coated fibre. Parameters influencing this extraction step, such as solution pH, sampling time and temperature are discussed. Furthermore, the overall extraction process takes into account the stability of cocaine in alkaline aqueous solutions at different temperatures. Cocaine degradation rate was determined by capillary electrophoresis using the short end injection procedure. In the selected extraction conditions, less than 5% of cocaine was degraded after 60 min. From a qualitative point of view, a significant gain in selectivity was obtained with the incorporation of SPME in the extraction procedure. As a consequence of SPME clean-up, shorter columns could be used and analysis time was reduced to 6 min compared to 35 min with conventional GC. Quantitative results led to a cocaine content of 0.70 +/- 0.04% in dry leaves (RSD <5%) which agreed with previous investigations. PMID:16384568

  4. Thin-layer chromatography-pyrolysis-gas chromatography-mass spectrometry: a multidimensional approach to marine lipid class and molecular species analysis.

    PubMed

    Hudson, E D; Helleur, R J; Parrish, C C

    2001-04-01

    A new multidimensional chromatographic method is described in which material separated into lipid-class bands on silica-coated quartz thin-layer chromatography (TLC) rods (Chromarods) is desorbed using a pyrolysis unit interface and introduced directly into a gas chromatograph-mass spectrometer for molecular species analysis. Steryl esters, wax esters, hydrocarbons, ketones, and fatty-acid methyl esters (FAMEs) are thermally desorbed without pretreatment. In order to desorb free sterols, monoacylglycerols (MAGs), aliphatic alcohols, and free fatty acids, the esters are converted to trimethylsilyl derivatives on the rod. Triacylglycerols and phospholipids are converted to FAMEs by thermochemolysis with tetramethylammonium hydroxide. The method's utility is demonstrated with lipids from seawater particulate matter by first confirming the identity of lipid bands with the appropriate standards. The wax ester-steryl ester TLC band contained no more than 8% steryl esters. Wax esters of up to C42 are detected. In six individual acyl lipid classes, C14-C22 fatty acids are detected with C16 acids predominant in all but wax esters. C16-C22 MAGs are identified in the complex acetone-mobile polar lipid band. The method successfully extends the scope of latroscan TLC-flame-ionization detection on Chromarods, which is a widely used technique for lipid-class analysis. Modification of the pyrolysis probe to handle intact TLC rods is a future objective. PMID:11318066

  5. Simple analysis of naphthalene, fluorene, and anthracene in whole blood by gas chromatography/mass spectrometry after headspace-solid phase microextraction.

    PubMed

    Akdoğan, Hatice Ardag

    2011-01-01

    A simple and sensitive method for the simultaneous analysis of naphthalene, fluorene, and anthracene in whole blood was developed using headspace-solid-phase microextraction (SPME) and GC/MS. A 0.5 g whole blood sample, 5 microL naphthalene, fluorene, and anthracene (50 microg/mL) as spiked standards, and 0.5 mL sodium hydroxide were placed into a 12 mL vial and sealed rapidly. The vial was immediately heated to 70 degrees C in an aluminium block heater, the needle of the SPME device was inserted through the septum of the vial, and the extraction fiber was exposed to the headspace for 15 min. Afterwards, the compounds extracted by the fiber were desorbed simultaneously by exposing the fiber in the gas chromatograph injection port. No interferences were found, and the time for analysis was about 30 min for one sample. This method was applied to a suicide case in which the victim ingested naphthalene, fluorene, and anthracene. PMID:22320097

  6. Comparison of electrospray ionization and atmospheric pressure photoionization liquid chromatography mass spectrometry methods for analysis of ergot alkaloids from endophyte-infected sleepygrass (Achnatherum robustum).

    PubMed

    Jarmusch, Alan K; Musso, Ashleigh M; Shymanovich, Tatsiana; Jarmusch, Scott A; Weavil, Miranda J; Lovin, Mary E; Ehrmann, Brandie M; Saari, Susanna; Nichols, David E; Faeth, Stanley H; Cech, Nadja B

    2016-01-01

    Ergot alkaloids are mycotoxins with an array of biological effects. With this study, we investigated for the first time the application of atmospheric pressure photoionization (APPI) as an ionization method for LC-MS analysis of ergot alkaloids, and compared its performance to that of the more established technique of electrospray ionization (ESI). Samples of the grass Achnatherum robustum infected with the ergot producing Epichloë fungus were extracted using cold methanol and subjected to reserved-phase HPLC-ESI-MS and HPLC-APPI-MS analysis. The ergot alkaloids ergonovine and lysergic acid amide were detected in these samples, and quantified via external calibration. Validation parameters were recorded in accordance with ICH guidelines. A triple quadrupole MS operated in multiple reaction monitoring yielded the lowest detection limits. The performance of APPI and ESI methods was comparable. Both methods were subject to very little matrix interference, with percent recoveries ranging from 82% to 100%. As determined with HPLC-APPI-MS quantification, lysergic acid amide and ergonovine were extracted from an A. robustum sample infected with the Epichloë fungus at concentrations of 1.143±0.051 ppm and 0.2822±0.0071 ppm, respectively. There was no statistically significant difference between these concentrations and those determined using ESI for the same samples. PMID:26340558

  7. Development of a sensitive and selective liquid chromatography-mass spectrometry method for high throughput analysis of paralytic shellfish toxins using graphitised carbon solid phase extraction.

    PubMed

    Boundy, Michael J; Selwood, Andrew I; Harwood, D Tim; McNabb, Paul S; Turner, Andrew D

    2015-03-27

    Routine regulatory monitoring of paralytic shellfish toxins (PST) commonly employs oxidative derivitisation and complex liquid chromatography fluorescence detection methods (LC-FL). The pre-column oxidation LC-FL method is currently implemented in New Zealand and the United Kingdom. When using this method positive samples are fractionated and two different oxidations are required to confirm the identity and quantity of each PST analogue present. There is a need for alternative methods that are simpler, provide faster turnaround times and have improved detection limits. Hydrophilic interaction liquid chromatography (HILIC) HPLC-MS/MS analysis of PST has been used for research purposes, but high detection limits and substantial sample matrix issues have prevented it from becoming a viable alternative for routine monitoring purposes. We have developed a HILIC UPLC-MS/MS method for paralytic shellfish toxins with an optimised desalting clean-up procedure on inexpensive carbon solid phase extraction cartridges for reduction of matrix interferences. This represents a major technical breakthrough and allows sensitive, selective and rapid analysis of paralytic shellfish toxins from a variety of sample types, including many commercially produced bivalve molluscan shellfish species. Additionally, this analytical approach avoids the need for complex calculations to determine sample toxicity, as unlike other methods each PST analogue is able to be quantified as a single resolved peak. This article presents the method development and optimisation information. A thorough single laboratory validation study has subsequently been performed and this data will be presented elsewhere. PMID:25704772

  8. Polymer-coated sample cup for quantitative analysis of semi-volatile phthalates in polymeric materials by thermal desorption-gas chromatography-mass spectrometry.

    PubMed

    Hosaka, Akihiko; Watanabe, Atsushi; Watanabe, Chuichi; Teramae, Norio; Ohtani, Hajime

    2015-04-24

    A new "polymer-coated" sample cup useful for the analysis of phthalates in polymeric materials by thermal desorption (TD)-GC/MS using a temperature programmable furnace type pyrolyzer as a TD device was developed to suppress the emission of semi-volatile phthalates such as dimethyl phthalate (DMP) and diethyl phthalate (DEP) during the measurements. The inner surface of a sample cup was coated by polymers which act as a sorbent for the phthalates. Three polymers, polyvinyl chloride, polystyrene and poly (methyl methacrylate), were chosen as the coating polymers. A mixture of ten phthalates including DMP and DEP was used as the test sample to estimate the performance of the sample cups. When a conventional sample cup without any polymer coating was used, 90 and 50% reductions in the peak areas of DMP and DEP were respectively observed at the waiting time of 200 min. On the contrary, no reduction of peak area of DMP and DEP during the same waiting time was observed with any one of the three coating polymers at the proper polymer film thickness. These results suggest that the polymer-coated sample cup suppresses the emission of semi-volatile phthalates and is effective for the analysis of phthalates containing DMP and DEP by TD-GC/MS. PMID:25795398

  9. 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 μl. 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

  10. 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

  11. A charged aerosol detector/chemiluminescent nitrogen detector/liquid chromatography/mass spectrometry system for regular and fragment compound analysis in drug discovery.

    PubMed

    Jiang, Yutao; Hascall, Daniel; Li, Delia; Pease, Joseph H

    2015-09-11

    In this paper, we introduce a high throughput LCMS/UV/CAD/CLND system that improves upon previously reported systems by increasing both the quantitation accuracy and the range of compounds amenable to testing, in particular, low molecular weight "fragment" compounds. This system consists of a charged aerosol detector (CAD) and chemiluminescent nitrogen detector (CLND) added to a LCMS/UV system. Our results show that the addition of CAD and CLND to LCMS/UV is more reliable for concentration determination for a wider range of compounds than either detector alone. Our setup also allows for the parallel analysis of each sample by all four detectors and so does not significantly increase run time per sample. PMID:26256922

  12. Improved gas chromatography/mass spectrometry analysis of barbiturates in urine using centrifuge-based solid-phase extraction, methylation, with d5-pentobarbital as internal standard.

    PubMed

    Liu, R H; McKeehan, A M; Edwards, C; Foster, G; Bensley, W D; Langner, J G; Walia, A S

    1994-11-01

    Effective solid-phase extraction, derivatization, and GC/MS procedures are developed for the simultaneous determinations of butalbital, amobarbital, pentobarbital, and secobarbital, using a deuterated pentobarbital (d5-pentobarbital) as the internal standard. Buffered (pH 7) urine samples were extracted with Bond Elute Certify II cartridge. Iodomethane/tetramethylammonium hydroxide in dimethylsulfoxide was used for methylation, while a HP 5970 MSD equipped with a 13 m J & W DB-5 column (5% phenyl polysiloxane phase) and the Thru-Put Target software package were used for GC/MS analysis and data processing. This protocol was found to be superior, in both chromatographic performance characteristics and quantitation results, over a liquid-liquid extraction procedure without derivatization using hexobarbital as the internal standard. Extraction recoveries observed from control samples containing four barbiturates range from 80% to 90%. Good one-point calibration data are obtained for all four barbiturates in the 50 to 3200 ng/mL range. Interestingly, the one-point calibration data for pentobarbital are inferior to the other three barbiturates--due to interference from the internal standard (d5-pentobarbital). The calibration data of pentobarbital are best described by a hyperbolic curve regression model. Precision data (% CV) for GC/MS analysis, over-all procedure, and day-to-day performance are approximately 2.0%, 6.0%, and 8.0%, respectively. With the use of a 2 mL sample size, the attainable detection limit is approximately 20 ng/mL. PMID:7815030

  13. Determination of pharmaceuticals and antiseptics in water by solid-phase extraction and gas chromatography/mass spectrometry: analysis via pentafluorobenzylation and stable isotope dilution.

    PubMed

    Yu, Jim T; Bisceglia, Kevin J; Bouwer, Edward J; Roberts, A Lynn; Coelhan, Mehmet

    2012-04-01

    A sensitive yet robust analytical method is presented for the simultaneous determination of 12 human pharmaceuticals (valproic acid, phenytoin, ibuprofen, gabapentin, acetaminophen, gemfibrozil, naproxen, ketoprofen, secobarbital, phenobarbital, 5-fluorouracil, and diclofenac) and 6 antiseptics (biosol, biphenylol, p-chloro-m-cresol, p-chloro-m-xylenol, chlorophene, and triclosan). The method employs solid-phase extraction (SPE) followed by a novel pentafluorobenzylation using a mixture of acetontrile/water (1/1, v/v). The method is simple to perform (derivatization can be completed in a single test tube) and eliminates the need for any solvent/SPE cartridge drying or blow-down. It affords excellent resolution, high sensitivity and reproducibility, and freedom from interference even for matrices as complex as untreated sewage. The method was applied to the analysis of sewage samples using 15 isotopically labeled surrogates, which resulted in the detection of 10 of the 12 pharmaceuticals and all of the antiseptics sought. Ten of 15 surrogates were synthesized from pure analytes by a simple H-D exchange reaction employing D(2)O and D(2)SO(4). Measured recoveries were sensitive to matrix effects and varied substantially among analytes, indicative of the limitations associated with using a single surrogate standard. PMID:22367332

  14. Application of multiwalled carbon nanotubes as sorbents for the extraction of mycotoxins in water samples and infant milk formula prior to high performance liquid chromatography mass spectrometry analysis.

    PubMed

    Socas-Rodríguez, Bárbara; González-Sálamo, Javier; Hernández-Borges, Javier; Rodríguez Delgado, Miguel Ángel

    2016-05-01

    In this work, a simple and environmental friendly methodology has been developed for the analysis of a group of six mycotoxins with estrogenic activity produced by Fusarium species (i.e. zearalanone, zearalenone, α-zearalanol, β-zearalanol, α-zearalenol, and β-zearalenol), using microdispersive SPE the symbol micro should de before dSPE with multiwalled carbon nanotubes as sorbent. Separation, determination, and quantification were achieved by HPLC coupled to ion trap MS with an ESI interface. Parameters affecting the extraction efficiency of µ-dSPE such as pH of the sample, amount of multiwalled carbon nanotubes, and type and volume of elution solvent, were studied and optimized. The methodology was validated for mineral, pond, and wastewater as well as for powdered infant milk using 17β-estradiol-2,4,16,16,17-d5 (17β-E2 -D5 ) as internal standard, obtaining recoveries ranging from 85 to 120% for the three types of water samples and from 77 to 115% for powdered infant milk. RSD values were lower than 10%. The LOQs achieved were in the range 0.05-2.90 μg/L for water samples and 2.02-31.9 μg/L for powdered infant milk samples. PMID:26892029

  15. Analysis of volatile phenols in alcoholic beverage by ethylene glycol-polydimethylsiloxane based stir bar sorptive extraction and gas chromatography-mass spectrometry.

    PubMed

    Zhou, Qin; Qian, Yanping; Qian, Michael C

    2015-04-17

    An ethylene glycol (EG)/polydimethylsiloxane (PDMS) copolymer based stir bar sorptive extraction (SBSE)-GC-MS method was developed for the analysis of volatile phenols (4-ethylphenol, 4-vinylphenol, 4-ethylguaiacol, and 4-vinylguaiacol) in alcoholic beverages. The beverage samples were diluted with phosphate buffer (1M, pH 7) and extracted with an EG/PDMS stir bar. Volatile phenols were thermally desorbed and analyzed by GC-MS. Parameters affecting extraction efficiency were studied including ionic strength, pH, extraction time, ethanol content and nonvolatile matrix. Good correlation coefficients with R(2) in the range of 0.994-0.999 were obtained for volatile phenol concentration of 5-500μg/L. Recovery for all phenols were from 95.7% to 104.4% in a beer matrix and 81.4% to 97.6% in a wine matrix. The method had a standard deviation less than 5.8% for all volatile phenols. The limit of quantification (LOQs) in beer samples was lower than 3μg/L. The method was further applied to analyze the concentrations of volatile phenols in beer, wine and other alcoholic beverage samples. PMID:25766496

  16. Gas chromatography-mass spectrometry of hexafluoroacetone derivatives: First time utilization of a gaseous phase derivatizing agent for analysis of extraterrestrial amino acids.

    PubMed

    Geffroy-Rodier, C; Buch, A; Sternberg, R; Papot, S

    2012-07-01

    Within the perspective of the current and next space missions to Mars (MSL 2011 and Exomars 2016-2018), the detection and enantioselective separation of building blocks such as the amino acids are important subjects which are becoming fundamental for the search for traces of life on the surface and subsurface of Mars. In this work, we have developed and optimized a method adapted to space experimentation to derivatize and analyze amino acids, using hexafluoroacetone as the derivatizing agent. The temperature, duration of the derivative transfer to the analyser, and chromatographic separation parameters have been optimized to meet the instrument design constraints imposed on devices for extraterrestrial experiments. The work presented in this rationale has established that hexafluoroacetone, in addition to its intrinsic qualities, such as the production of light-weight derivatives (no racemization) and great resistance to the drastic operating conditions, has indeed facilitated simple and fast derivatization that appears to be suitable for in situ analysis in space. By using hexafluoroacetone as the derivatizing agent, we successfully identified, 21 amino acids including 12 of the 20 proteinic amino acids without stirring or extraction steps. Ten of these derivatized amino acids were enantioselectively separated. The precision and accuracy measurements for the D/L ratio showed that the proposed method was also suitable for the determination of both enantioselective forms of most of the tested amino acids. The limits of detection obtained were lower than the ppb level of organic molecules detected in Martian meteorites. PMID:22633064

  17. Search for evidence of life in space: analysis of enantiomeric organic molecules by N,N-dimethylformamide dimethylacetal derivative dependant Gas Chromatography-Mass Spectrometry.

    PubMed

    Freissinet, C; Buch, A; Sternberg, R; Szopa, C; Geffroy-Rodier, C; Jelinek, C; Stambouli, M

    2010-01-29

    Within the context of the future space missions to Mars (MSL 2011 and Exomars 2016), which aim at searching for traces of life at the surface, the detection and quantitation of enantiomeric organic molecules is of major importance. In this work, we have developed and optimized a method to derivatize and analyze chiral organic molecules suitable for space experiments, using N,N-dimethylformamide dimethylacetal (DMF-DMA) as the derivatization agent. The temperature, duration of the derivatization reaction, and chromatographic separation parameters have been optimized to meet instrument design constraints imposed upon space experiment devices. This work demonstrates that, in addition to its intrinsic qualities, such as production of light-weight derivatives and a great resistance to drastic operating conditions, DMF-DMA facilitates simple and fast derivatization of organic compounds (three minutes at 140 degrees C in a single-step) that is suitable for an in situ analysis in space. By using DMF-DMA as the derivatization agent, we have successfully identified 19 of the 20 proteinic amino acids and been able to enantiomerically separate ten of the potential 19 (glycine being non-chiral). Additionally, we have minimized the percentage of racemized amino acid compounds produced by optimizing the conditions of the derivatization reaction itself. Quantitative linearity studies and the determination of the limit of detection show that the proposed method is also suitable for the quantitative determination of both enantiomeric forms of most of the tested amino acids, as limits of detection obtained are lower than the ppb level of organic molecules already detected in Martian meteorites. PMID:20036768

  18. Analysis of dexamethasone and betamethasone in bovine urine by purification with an "on-line" immunoaffinity chromatography-high-performance liquid chromatography system and determination by gas chromatography-mass spectrometry.

    PubMed

    Bagnati, R; Ramazza, V; Zucchi, M; Simonella, A; Leone, F; Bellini, A; Fanelli, R

    1996-03-15

    A method for the immunoaffinity extraction of dexamethasone and betamethasone in bovine urine, followed by high-pressure liquid chromatography (HPLC) fractionation and gas chromatography-mass spectrometry determination, is described. A commercial immunoaffinity gel, containing antibodies raised against dexamethasone, was used to prepare an immunoaffinity cartridge which was inserted in an automatic HPLC system for on-line extraction and purification. By injecting urine samples (spiked with flumethasone as internal standard) directly into the system, it was possible to collect purified fractions, containing the analytes of interest. The fractions were dried and derivatized to yield the tetra-trimethylsilyl derivatives of the three corticosteroids, which were analyzed by selected ion monitoring gas chromatography-mass spectrometry. The method allowed a very good purification of samples and reached a detection limit of 0.1 ng/ml for dexamethasone and 0.2 ng/ml for betamethasone. Several samples, coming from a steer treated with dexamethasone and from other bovines coming from breedings in northern Italy, were analyzed with the method described. Dexamethasone levels ranged from 0.12 to 146 ng/ml. PMID:8833319

  19. 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.

  20. Methods of Analysis by the U.S. Geological Survey National Water Quality Laboratory - Determination of Moderate-Use Pesticides and Selected Degradates in Water by C-18 Solid-Phase Extraction and Gas Chromatography/Mass Spectrometry

    USGS Publications Warehouse

    Sandstrom, Mark W.; Stroppel, Max E.; Foreman, William T.; Schroeder, Michael P.

    2001-01-01

    A method for the isolation and analysis of 21 parent pesticides and 20 pesticide degradates in natural-water samples is described. Water samples are filtered to remove suspended particulate matter and then are pumped through disposable solid-phase-extraction columns that contain octadecyl-bonded porous silica to extract the analytes. The columns are dried by using nitrogen gas, and adsorbed analytes are eluted with ethyl acetate. Extracted analytes are determined by capillary-column gas chromatography/mass spectrometry with selected-ion monitoring of three characteristic ions. The upper concentration limit is 2 micrograms per liter (?g/L) for most analytes. Single-operator method detection limits in reagent-water samples range from 0.00 1 to 0.057 ?g/L. Validation data also are presented for 14 parent pesticides and 20 degradates that were determined to have greater bias or variability, or shorter holding times than the other compounds. The estimated maximum holding time for analytes in pesticide-grade water before extraction was 4 days. The estimated maximum holding time for analytes after extraction on the dry 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. The method complements existing U.S. Geological Survey Method O-1126-95 (NWQL Schedules 2001 and 2010) by using identical sample preparation and comparable instrument analytical conditions so that sample extracts can be analyzed by either method to expand the range of analytes determined from one water sample.

  1. 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.

  2. 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

  3. Age determination of ballpoint pen ink by thermal desorption and gas chromatography-mass spectrometry.

    PubMed

    Bügler, Jürgen H; Buchner, Hans; Dallmayer, Anton

    2008-07-01

    Two main approaches can be used for determining the age of an ink: indirect dating and direct dating. Indirect dating is based on the chemical analysis of an ink followed by comparison with known samples in a reference collection. The collection should contain information about the inks including the market introduction dates. This approach may allow for an anachronism to be detected. The second concept is based on measuring ink components that change with age. The analysis of solvents in ballpoint inks may be a useful parameter for determining the age of ink on paper. In a previous study, the authors demonstrated that thermal desorption of ink directly from paper, followed by chemical analysis using gas chromatography-mass spectrometry (GC-MS), is a promising procedure for characterizing ink-binder resins and solvents. Preliminary tests showed that monitoring the evaporation of ink solvent from ink on paper is not a suitable method for ink dating. Thermal analysis of ink on paper in two steps revealed that fresh ink releases a relative amount of solvent at a certain low temperature in a defined period of time, which decreases as the ink ages. As a consequence, this relative amount of solvent released at a certain low temperature, and its decrease with time, can be used to estimate ink age. This age-dependent parameter was studied in 85 different inks ranging in age from 1 week to 1.5 years. It was found that some inks showed a significant decrease of this parameter up to an age of several months, and that the aging process can be monitored within this period. For other inks, however, the age-dependent parameter decreases relatively fast, e.g., within a few days, to a constant level, which can be too fast for casework. Based on these results, a general procedure for assessing the age of ballpoint pen inks on paper was developed. PMID:18503526

  4. Integration of Electrochemistry with Ultra Performance Liquid Chromatography/Mass Spectrometry (UPLC/MS)

    PubMed Central

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

    2015-01-01

    This study presents the development of ultra-performance liquid chromatography/mass spectrometry (UPLC/MS) combined with electrochemistry (EC) for the first time and its application for the structural analysis of disulfide bond-containing proteins/peptides. In our approach, a protein/peptide mixture sample undergoes fast UPLC separation and subsequent electrochemical reduction in an electrochemical flow cell followed by online MS and MS/MS analyses. The electrochemical cell is coupled to MS using our recently developed desorption electrospray ionization (DESI) interface. Using this UPLC/EC/DESI-MS method, disulfide bond-containing peptides can be differentiated from those without disulfide bonds as the former are electroactive and reducible. Tandem MS analysis of the disulfide-reduced peptide ions provides increased sequence and disulfide linkage pattern information. In a reactive DESI-MS detection experiment in which a supercharging reagent was used to dope the DESI spray solvent, increased charging was obtained for the UPLC-separated proteins. Strikingly, upon online electrolytic reduction, supercharged proteins (e.g., α-lactalbumin) showed even higher charging, which would be useful in top-down protein structure analysis as increased charges are known to promote protein ion dissociation. Also, the separation speed and sensitivity are enhanced by approximately 1~2 orders of magnitude by using UPLC for the LC/EC/MS platform, in comparison to the previously used high performance liquid chromatography (HPLC). This UPLC/EC/DESI-MS method combines the power of fast UPLC separation, fast electrochemical conversion and online MS structural analysis for a potentially valuable tool for proteomics research and bioanalysis. PMID:26307715

  5. [Simultaneous determination of 8 polybrominated biphenyls in human serum using gas chromatography-mass spectrometry].

    PubMed

    Liu, Xiao; Li, Jingguang; Huang, Feifei; Wu, Yongning

    2012-05-01

    A comprehensive analytical method based on gas chromatography-mass spectrometry (GC-MS) has been developed for the simultaneous determination of 8 polybrominated biphenyl congeners (PBBs: BB-15, 18, 52, 101, 153, 180, 194 and 206) in human serum. After the protein was removed, the sample was cleaned-up by an Oasis HLB solid-phase extraction (SPE) cartridge, then purified further by a two-layer cartridge containing activated silica gel and a mixture of silica gel and sulfuric acid, in which elution solvent was optimized. The eluent was evaporated to about 100 microL by a gentle nitrogen stream for GC-MS analysis. The separation was performed on a DB-5ms column (15 m x 0.25 mm x 0.1 microm) and the qualitative and quantitative analyses were carried out in electron impact (EI) selected ion monitoring (SIM) mode, in which isotope was used as internal standard. The limits of detection (LODs, 3.14 times of standard deviation) and the limits of quantification (LOQs, 10 times of standard deviation) were 0.002-0.029 ng/mL and 0.008-0.092 ng/mL respectively for the 8 PBBs. The average recoveries for all PBBs at three spiked levels were 74.24%-119.49% with the relative standard deviations in the range of 1.23%-12.02%. The method was verified by accurate analysis of BB-153 in organic contaminant standard reference materials (SRM) 1957 and 1958. This method is simple, rapid, accurate, precise and fit for the determination of PBBs in human serum. PMID:22934409

  6. Optimization of large-scale pseudotargeted metabolomics method based on liquid chromatography-mass spectrometry.

    PubMed

    Luo, Ping; Yin, Peiyuan; Zhang, Weijian; Zhou, Lina; Lu, Xin; Lin, Xiaohui; Xu, Guowang

    2016-03-11

    Liquid chromatography-mass spectrometry (LC-MS) is now a main stream technique for large-scale metabolic phenotyping to obtain a better understanding of genomic functions. However, repeatability is still an essential issue for the LC-MS based methods, and convincing strategies for long time analysis are urgently required. Our former reported pseudotargeted method which combines nontargeted and targeted analyses, is proved to be a practical approach with high-quality and information-rich data. In this study, we developed a comprehensive strategy based on the pseudotargeted analysis by integrating blank-wash, pooled quality control (QC) sample, and post-calibration for the large-scale metabolomics study. The performance of strategy was optimized from both pre- and post-acquisition sections including the selection of QC samples, insertion frequency of QC samples, and post-calibration methods. These results imply that the pseudotargeted method is rather stable and suitable for large-scale study of metabolic profiling. As a proof of concept, the proposed strategy was applied to the combination of 3 independent batches within a time span of 5 weeks, and generated about 54% of the features with coefficient of variations (CV) below 15%. Moreover, the stability and maximal capability of a single analytical batch could be extended to at least 282 injections (about 110h) while still providing excellent stability, the CV of 63% metabolic features was less than 15%. Taken together, the improved repeatability of our strategy provides a reliable protocol for large-scale metabolomics studies. PMID:26877181

  7. Triple sorbent thermal desorption/gas chromatography/mass spectrometry determination of vapor phase organic contaminants

    SciTech Connect

    Ma, C.Y.; Skeen, J.T.; Dindal, A.B.; Higgins, C.E.; Jenkins, R.A.

    1994-05-01

    A thermal desorption/ps chromatography/mass spectrometry (TD/GC/MS) has been evaluated for the determination of volatile organic compounds (VOCS) in vapor phase samples using Carbosieve S-III/Carbotrap/Carotrap C triple sorbent traps (TST) similar to those available from a commercial source. The analysis was carried out with a Hewlett-Packard 5985A or 5995 GC/MS system with a modified injector to adapt an inhouse manufactured short-path desorber for transferring desorbate directly onto a cryofocusing loop for subsequent GC/MS analysis. Vapor phase standards generated from twenty six compounds were used for method validation, including alkanes, alkyl alcohols, alkyl ketones, and alkyl nitrites, a group of representative compounds that have previously been identified in a target airborne matrix. The method was validated based on the satisfactory results in terms of reproducibility, recovery rate, stability, and linearity. A relative, standard deviation of 0.55 to 24.3 % was obtained for the entire TD process (generation of gas phase standards, spiking the standards on and desorbing from TST) over a concentration range of 20 to 500 ng/trap. Linear correlation coefficients for the calibration curves as determined ranged from 0.81 to 0.99 and limits of detection ranged from 3 to 76 ng. For a majority of standards, recoveries of greater than 90% were observed. For three selected standards spiked on TSTS, minimal loss (10 to 22%) was observed after storing the spiked in, a 4{degree}C refrigerator for 29 days. The only chromatographable artifact observed was a 5% conversion of isopropanol to acetone. The validated method been successfully applied, to the determination of VOCs collected from various emission sources in a diversified concentration range.

  8. Measurement of cocaine and metabolites in urine, meconium, and diapers by gas chromatography/mass spectrometry.

    PubMed

    Lombardero, N; Casanova, O; Behnke, M; Eyler, F D; Bertholf, R L

    1993-01-01

    Analytical methods were evaluated for measuring cocaine (CO), benzoylecgonine (BE), and ecgonine methyl ester (EME) in urine and methanolic extracts from meconium and diapers by isotope dilution gas chromatography/mass spectrometry (GC/MS). Volatile derivatives of the extracted drugs were generated before GC/MS analysis. Methanolic extracts from meconium and diapers were reconstituted in drug-free urine and treated as above. The limit of detection for the GC/MS method was calculated to be approximately 11 ng per mL. Within-run coefficients of variation (CVs) for urinary CO, BE, and EME were 5.7, 5.3, and 11.4 percent, respectively (N = 10); corresponding CVs for meconium 6.4, 10.7, and 21.9 percent (N = 8). Quantitative results were linear from 25 to 10,000 ng per g of meconium and 25 to 5,000 ng per mL of urine. Day-to-day precision varied from eight percent (CV) for BE in refrigerated or frozen urine to 34 percent for EME in refrigerated meconium. Recoveries of CO, BE, and EME from urine were 63, 19, and 42 percent, respectively; corresponding recoveries from meconium were 64, 21, and 25 percent. Cocaine and metabolites were extracted from wet but meconium-free diapers into methanol, which was evaporated before reconstituting in drug-free urine and extraction on a solid phase column. The CO, BE, and EME were detected in previously drug-free meconium after portions were deposited in a diaper which was wet with drug-positive urine. Unless precautions are taken to prevent extracorporeal contamination of meconium with urine, concentrations of CO and metabolites in meconium may be substantially augmented by contamination with urine. Analysis by GC/MS of CO and metabolites extracted from diapers provides an attractive alternative to collection of urine, which is difficult and may cause discomfort for the neonate. PMID:8239486

  9. Improved method for rapid detection of phthalates in bottled water by gas chromatography-mass spectrometry.

    PubMed

    Otero, Paz; Saha, Sushanta Kumar; Moane, Siobhan; Barron, John; Clancy, Gerard; Murray, Patrick

    2015-08-01

    An improved gas chromatography-mass spectrometry (GC-MS) method for simple, rapid and precise quantification of phthalates in drinking water is presented. This method was validated for bis (2-n-butoxyethyl) phthalate (DBEP), bis (2-n-ethylhexyl) phthalate (DEHP), butyl benzyl phthalate (BBP), di-butyl phthalate (DBP), diethyl phthalate (DEP), dihexyl phthalate (DHP), dimethyl phthalate (DMP), di-n-octyl phthalate (DNOP) and dinonyl phthalate (DINP). Linearity of 0.9984>r(2)>0.9975 in the range of 0.075-4.8μg/mL for the selected phthalates was obtained. Accuracy values were in the range of 93-114% and RSD% for the analysis of 1.2μg/mL of each phthalate was below 2.3% (n=9). This new method design has significantly improved the detection in terms of rapidity, specificity, repeatability and accuracy compared to available methods. The procedure has been applied to the analyses of three different brands of commercially available bottled mineral water and the corresponding plastic bottles. Phthalates were extracted with dichloromethane and re-constituted in cyclohexane prior to GC-MS analysis. When the validated GC-MS method was applied to the quantification of the selected phthalates in the samples, only DBP (up to 0.0675±0.0018μg/mL) and DEHP (up to 1.6848±0.1631μg/mL) were found. Furthermore, we provide specific data about the concentration of DBP and DEHP in bottled water attributable to migration of phthalates from respective plastic bottles. PMID:26134297

  10. Methods of analysis by the U. S. Geological Survey National Water Quality Laboratory; determination of pesticides in water by graphitized carbon-based solid-phase extraction and high-performance liquid chromatography/mass spectrometry

    USGS Publications Warehouse

    Furlong, Edward T.; Anderson, Bruce D.; Werner, Stephen L.; Soliven, Paul P.; Coffey, Laura J.; Burkhardt, Mark R.

    2001-01-01

    In 1996, the U.S. Geological Survey National Water Quality Laboratory (NWQL) developed and implemented a graphitized carbon-based solid-phase extraction and high-performance liquid chromatographic analytical method to determine polar pesticide concentrations in surface- and ground-water samples. Subsequently, the NWQL developed a complementary analysis that uses high-performance liquid chromatography/mass spectrometry to detect, identify, and quantify polar pesticides and pesticide metabolites in filtered water at concentrations as low as 10 nanograms per liter. This new method was designed to improve sensitivity and selectivity over the prior method, and to reduce known interferences from natural organic matter. In this new method, pesticides are extracted from filtered water samples by useing a 0.5-gram graphitized carbon-based solid-phase extraction cartridge, eluted from the cartridge, and concentrations determined by using high-perforance liquid chromatography with elecrospray ionization-mass spectrometry. The upper concentratoin limit is 1.000 microgram per liter (ug/L) for most compounds. Single-operator method detection limits in organic-free water samples fortified with pesticdes at a concentration of 0.025 ug/L ranged from 0.0019 to 0.022 ug/L for all compunds in the method. The grand mean (mean of mean recoveries for individual compounds) recoveries in organic-free water samples ranged from 72 to 89 percent, fortified wit hpesticides at three concentrations between 0.025 and 0.5 ug/L. Grand mean recoveries in ground- and surface-water samples ranged from 46 to 119 percent, also fortified with pesticies at three concentrations between 0.025 and 0.5 ug/L. Long-term recoveries from reagent water spikes were used to demonstrate that 38 of 65 compounds can be reported without qualification of the quantitative result across the analytical range of the method. The remaining 27 are reported with qualified estimates of concentration because of greater variability of recovery.

  11. [Determination of residual glycol ethers in leather and leather products by gas chromatography/mass spectrometry].

    PubMed

    Wang, Ghengyun; Zhang, Weiya; Li, Lixia; Shen, Yalei; Lin, Junfeng; Xie, Tangtang; Chu, Naiqing

    2014-08-01

    An effective method was established for the simultaneous determination of residual glycol ethers in leather and leather products by gas chromatography/mass spectrometry. Glycol ethers in leather and leather products were ultrasonically extracted at 45 °C, using ethyl acetate as the extraction solvent. The extracts were purified by solid phase extraction (SPE) columns, and then analyzed by gas chromatography/mass spectrometry in selected ion monitoring mode. The content of each analyte was calibrated by external standard method. The limit of detection of ethylene glycol ethyl ether (EGEE) was 0. 10 mg/kg under the condition of signal to noise (S/N) of 3 and the limits of the other 11 glycol ethers were all less than 0.05 mg/kg. The spiked recoveries varied from 81. 2% to 95. 5% at three different spiked levels with the relative standard deviations (RSDs) ranged from 1.4% to 6. 6%. The proposed method is simple, rapid and accurate, with the limits of detection much less than the requirements of the Regulation Concerning Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) of European Union. It is applicable to the determination of residual glycol ethers in leather and leather products, and provides a reference for the relevant testing standards. PMID:25434128

  12. Composition of ultrathin binary polymer brushes by thermogravimetry-gas chromatography-mass spectrometry.

    PubMed

    Antonioli, Diego; Sparnacci, Katia; Laus, Michele; Ferrarese Lupi, Federico; Giammaria, Tommaso Jacopo; Seguini, Gabriele; Ceresoli, Monica; Perego, Michele; Gianotti, Valentina

    2016-05-01

    In the present paper, a reliable and rugged thermogravimetry-gas chromatography-mass spectrometry (TGA-GC-MS) method was developed to determine the composition of ultrathin films consisting of binary blends of functional polystyrene (PS) and polymethylmethacrylate (PMMA) grafted to a silicon wafer. A general methodology will be given to address the composition determination problem for binary or even multicomponent polymer brush systems using the PS/PMMA-based samples as a paradigmatic example. In this respect, several distinct tailor-made materials were developed to ensure reliable calibration and validation stages. The analytical method was tested on unknown samples to follow the composition evolution in PS/PMMA brushes during the grafting reaction. A preferential grafting of the PMMA was revealed in full agreement with its preferential interaction with the SiO2 polar surface. Graphical abstract A reliable and rugged thermogravimetry-gas chromatography-mass spectrometry (TGA-GC-MS) method was developed to determine the composition of ultrathin films consisting of binary blends of functional polystyrene (PS) and polymethylmethacrylate (PMMA) grafted to a silicon wafer. PMID:26873220

  13. Metabolomics by Gas Chromatography-Mass Spectrometry: Combined Targeted and Untargeted Profiling.

    PubMed

    Fiehn, Oliver

    2016-01-01

    Gas chromatography-mass spectrometry (GC-MS)-based metabolomics is ideal for identifying and quantitating small-molecule metabolites (<650 Da), including small acids, alcohols, hydroxyl acids, amino acids, sugars, fatty acids, sterols, catecholamines, drugs, and toxins, often using chemical derivatization to make these compounds sufficiently volatile for gas chromatography. This unit shows how GC-MS-based metabolomics allows integration of targeted assays for absolute quantification of specific metabolites with untargeted metabolomics to discover novel compounds. Complemented by database annotations using large spectral libraries and validated standard operating procedures, GC-MS can identify and semiquantify over 200 compounds from human body fluids (e.g., plasma, urine, or stool) per study. Deconvolution software enables detection of more than 300 additional unidentified signals that can be annotated through accurate mass instruments with appropriate data processing workflows, similar to untargeted profiling using liquid chromatography-mass spectrometry. GC-MS is a mature technology that uses not only classic detectors (quadrupole) but also target mass spectrometers (triple quadrupole) and accurate mass instruments (quadrupole-time of flight). This unit covers sample preparation from mammalian samples, data acquisition, quality control, and data processing. © 2016 by John Wiley & Sons, Inc. PMID:27038389

  14. 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

  15. Determination of Synthetic Cathinones in Urine Using Gas Chromatography-Mass Spectrometry Techniques.

    PubMed

    Hong, Wei-Yin; Ko, Ya-Chun; Lin, Mei-Chih; Wang, Po-Yu; Chen, Yu-Pen; Chiueh, Lih-Ching; Shih, Daniel Yang-Chih; Chou, Hsiu-Kuan; Cheng, Hwei-Fang

    2016-01-01

    In recent years, the abuse of synthetic cathinones has increased considerably. This study proposes a method, based on gas chromatography/mass spectrometry (GC-MS), to analyze and quantify six synthetic cathinones in urine samples: mephedrone (4-MMC), methylone (bk-MDMA), butylone, ethylone, pentylone and methylenedioxypyrovalerone (MDPV). In our procedure, the urine samples undergo solid-phase extraction (SPE) and derivatization prior to injection into the GC-MS device. Separation is performed using a HP-5MS capillary column. The use of selective ion monitoring (SIM mode) makes it is good sensitivity in this method, and the entire analysis process is within 18 min. In addition, the proposed method maintains linearity in the calibration curve from 50 to 2,000 ng/mL (r(2) > 0.995). The limit of detection of this method is 5 ng/mL, with the exception of MDPV (20 ng/mL); the limit of quantification is 20 ng/mL, with the exception of MDPV (50 ng/mL). In testing, the extraction performance of SPE was between 82.34 and 104.46%. Precision and accuracy results were satisfactory <15%. The proposed method was applied to six real urine samples, one of which was found to contain 4-MMC and bk-MDMA. Our results demonstrate the efficacy of the proposed method in the identification of synthetic cathinones in urine, with regard to the limits of detection and quantification. This method is highly repeatable and accurate. PMID:26410364

  16. Identification of several human urinary metabolites of 6-benzoyl benzoxazolinone by gas chromatography/mass spectrometry.

    PubMed

    Bastide, M; Chabard, J L; Lartigue, C; Bargnoux, H; Petit, J; Berger, J A; Mansour, H A; Lesieur, D; Buch, N

    1991-08-01

    The biotransformation of 6-benzoyl benzoxazolinone (6-BB), a non-narcotic peripheral analgesic, was studied in eight healthy volunteers after oral administration of a single dose of 1 g. Urinary metabolites were extracted either with ethyl acetate at different pH values or by percolating at pH 5 through Amberlite XAD 2 ion-exchange resin. Eluates were concentrated under vacuum, purified by thin-layer chromatography and analysed by gas chromatography/mass spectrometry or direct insertion probe mass spectrometry. Metabolites were identified with reference to the mass spectra of various synthesized compounds assumed to be metabolites of 6-BB, as N-methylated or monohydroxylated compounds. Another metabolic pathway was cleavage of the benzoxazolinone heterocycle giving 2-amino-5-benzoyl phenol after hydrolysis and decarboxylation. N-methyl, N-acetyl and hydroxylated metabolites having an amino-5-benzoyl phenol structure were also found. PMID:1768705

  17. Analysis of organo-chlorine pesticides residue in raw coffee with a modified "quick easy cheap effective rugged and safe" extraction/clean up procedure for reducing the impact of caffeine on the gas chromatography-mass spectrometry measurement.

    PubMed

    Bresin, Bruno; Piol, Maria; Fabbro, Denis; Mancini, Maria Antonietta; Casetta, Bruno; Del Bianco, Clorinda

    2015-01-01

    The control of pesticide residues on raw coffee is a task of great importance due to high consumption of this beverage in Italy and in many other countries. High caffeine content can hamper extraction and measurement of any pesticide residue. A tandem extraction protocol has been devised by exploiting the quick easy cheap effective rugged and safe (QuEChERS) scheme for extraction, coupled to a dispersive liquid-liquid micro-extraction (DLLME) in order to drastically reduce caffeine content in the final extract. Gas chromatography-mass spectrometry (GC-MS) has been used for quantification of organo-chlorine pesticides in single ion monitoring (SIM) mode. Method has been validated and performances meet the criteria prescribed by European Union regulations. PMID:25537171

  18. 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.

  19. Analysis of acrylonitrile, 1,3-butadiene, and related compounds in acrylonitrile-butadiene-styrene copolymers for kitchen utensils and children's toys by headspace gas chromatography/mass spectrometry.

    PubMed

    Ohno, Hiroyuki; Kawamura, Yoko

    2010-01-01

    A headspace gas chromatography/mass spectrometry method was developed for the simultaneous determination of the residual levels of acrylonitrile (AN), 1,3-butadiene (1,3-BD), and their related compounds containing propionitrile (PN) and 4-vinyl-1-cyclohexene (4-VC) in acrylonitrile-butadiene-styrene (ABS) copolymers for kitchen utensils and children's toys. A sample was cut into small pieces, then N,N-dimethylacetamide and an internal standard were added in a sealed headspace vial. The vial was incubated for 1 h at 90 degrees C and the headspace gas was analyzed by gas chromatography/mass spectrometry. The recovery rates of the analytes were 93.3-101.8% and the coefficients of variation were 0.3-6.5%. In ABS copolymers, the levels were 0.3-50.4 microg/g for AN, ND-4.5 microg/g for PN, 0.06-1.58 microg/g for 1,3-BD, and 1.1-295 microg/g for 4-VC. The highest level was found for 4-VC, which is a dimer of 1,3-BD, and the next highest was for AN, which is one of the monomers of the ABS copolymer. Furthermore, the method was also applied to acrylonitrile-styrene (AS) copolymers and polystyrenes (PS) for kitchen utensils, and nitrile-butadiene rubber (NBR) gloves. In AS copolymers, AN and PN were detected at 16.8-54.5 and 0.8-6.9 microg/g, respectively. On the other hand, the levels in PS and NBR samples were all low. PMID:21313827

  20. Analysis of ketamine and norketamine in urine by automatic solid-phase extraction (SPE) and positive ion chemical ionization-gas chromatography-mass spectrometry (PCI-GC-MS).

    PubMed

    Kim, Eun-mi; Lee, Ju-seon; Choi, Sang-kil; Lim, Mi-ae; Chung, Hee-sun

    2008-01-30

    Ketamine (KT) is widely abused for hallucination and also misused as a "date-rape" drug in recent years. An analytical method using positive ion chemical ionization-gas chromatography-mass spectrometry (PCI-GC-MS) with an automatic solid-phase extraction (SPE) apparatus was studied for the determination of KT and its major metabolite, norketamine (NK), in urine. Six ketamine suspected urine samples were provided by the police. For the research of KT metabolism, KT was administered to SD rats by i.p. at a single dose of 5, 10 and 20mg/kg, respectively, and urine samples were collected 24, 48 and 72 h after administration. For the detection of KT and NK, urine samples were extracted on an automatic SPE apparatus (RapidTrace, Zymark) with mixed mode type cartridge, Drug-Clean (200 mg, Alltech). The identification of KT and NK was by PCI-GC-MS. m/z238 (M+1), 220 for KT, m/z 224 (M+1), 207 for NK and m/z307 (M+1) for Cocaine-D(3) as internal standard were extracted from the full-scan mass spectrum and the underlined ions were used for quantitation. Extracted calibration curves were linear from 50 to 1000 ng/mL for KT and NK with correlation coefficients exceeding 0.99. The limit of detection (LOD) was 25 ng/mL for KT and NK. The limit of quantitation (LOQ) was 50 ng/mL for KT and NK. The recoveries of KT and NK at three different concentrations (86, 430 and 860 ng/mL) were 53.1 to 79.7% and 45.7 to 83.0%, respectively. The intra- and inter-day run precisions (CV) for KT and NK were less than 15.0%, and the accuracies (bias) for KT and NK were also less than 15% at the three different concentration levels (86, 430 and 860 ng/mL). The analytical method was also applied to real six KT suspected urine specimens and KT administered rat urines, and the concentrations of KT and NK were determined. Dehydronorketamine (DHNK) was also confirmed in these urine samples, however the concentration of DHNK was not calculated. SPE is simple, and needs less organic solvent than liquid-liquid extraction (LLE), and PCI-GC-MS can offer both qualitative and quantitative information for urinalysis of KT in forensic analysis. PMID:17553643

  1. 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.

  2. Community air monitoring for pesticides-part 2: multiresidue determination of pesticides in air by gas chromatography, gas chromatography-mass spectrometry, and liquid chromatography-mass spectrometry.

    PubMed

    Hengel, Matt; Lee, P

    2014-03-01

    Two multiresidue methods were developed to determine pesticides in air collected in California. Pesticides were trapped using XAD-4 resin and extracted with ethyl acetate. Based on an analytical method from the University of California Davis Trace Analytical Laboratory, pesticides were detected by analyzing the extract by gas chromatography-mass spectrometry (GC-MS) to determine chlorothalonil, chlorthal-dimethyl, cycloate, dicloran, dicofol, EPTC, ethalfluralin, iprodione, mefenoxam, metolachlor, PCNB, permethrin, pronamide, simazine, trifluralin, and vinclozolin. A GC with a flame photometric detector was used to determine chlorpyrifos, chlorpyrifos oxon, diazinon, diazinon oxon, dimethoate, dimethoate oxon, fonophos, fonophos oxon, malathion, malathion oxon, naled, and oxydemeton. Trapping efficiencies ranged from 78 to 92 % for low level (0.5 μg) and 37-104 % for high level (50 and 100 μg) recoveries. Little to no degradation of compounds occurred over 31 days; recoveries ranged from 78 to 113 %. In the California Department of Food and Agriculture (CDFA) method, pesticides were detected by analyzing the extract by GC-MS to determine chlorothalonil, chlorpyrifos, cypermethrin, dichlorvos, dicofol, endosulfan 1, endosulfan sulfate, oxyfluorfen, permethrin, propargite, and trifluralin. A liquid chromatograph coupled to a MS was used to determine azinphos-methyl, chloropyrifos oxon, DEF, diazinon, diazinon oxon, dimethoate, dimethoate oxon, diuron, EPTC, malathion, malathion oxon, metolachlor, molinate, norflurazon, oryzalin, phosmet, propanil, simazine and thiobencarb. Trapping efficiencies for compounds determined by the CDFA method ranged from 10 to 113, 22 to 114, and 56 to 132 % for 10, 5, and 2 μg spikes, respectively. Storage tests yielded 70-170 % recovery for up to 28 days. These multiresidue methods represent flexible, sensitive, accurate, and cost-effective ways to determine residues of various pesticides in ambient air. PMID:24370860

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

    PubMed

    Weckwerth, W; Willmitzer, L; Fiehn, O

    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 beta-elimination of phosphate from phospho-Ser/Thr followed by Micheal addition of ethanethiol and/or ethane-d(5)-thiol selectively at the vinyl moiety of dehydroalanine and dehydroamino-2-butyric acid. The method was evaluated using the model phosphoprotein alpha(S1)-casein, for which three phosphopeptides were found after tryptic digestion. Reproducibility of the relative quantification of seven independent replicates was found to be 11% SD. The dynamic range covered two orders of magnitude, and quantification was linear for mixtures of 0 to 100% alpha(S1)-casein and dephospho-alpha(S1)-casein (R(2) = 0.986). Additionally, the method allowed protein identification and determination of the phosphorylation sites via MS/MS fragmentation. PMID:10962490

  4. 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

  5. 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

  6. Qualitative Gas Chromatography-Mass Spectrometry Analyses Using Amines as Chemical Ionization Reagent Gases

    NASA Astrophysics Data System (ADS)

    Little, James L.; Howard, Adam S.

    2013-12-01

    Ammonia is a very useful chemical ionization (CI) reagent gas for the qualitative analyses of compounds by positive ion gas chromatography-mass spectrometry (GCMS). The gas is readily available, inexpensive, and leaves no carbon contamination in the MS source. Compounds of interest to our laboratory typically yield abundant protonated or ammoniated species, which are indicative of a compound's molecular weight. Nevertheless, some labile compounds fragment extensively by substitution and elimination reactions and yield no molecular weight information. In these cases, a CI reagent gas mixture of methylamine in methane prepared dynamically was found to be very useful in obtaining molecular weight data. Likewise, deuterated ammonia and deuterated methylamine are useful CI reagent gases for determining the exchangeable protons in organic compounds. Deuterated methylamine CI reagent gas is conveniently prepared by dynamically mixing small amounts of methylamine with excess deuterated ammonia.

  7. Characterization and quantification of fluoxymesterone metabolite in horse urine by gas chromatography/mass spectrometry.

    PubMed

    Yamada, Masayuki; Aramaki, Sugako; Hosoe, Tomoo; Kurosawa, Masahiko; Kijima-Suda, Isao; Saito, Koichi; Nakazawa, Hiroyuki

    2008-07-01

    Fluoxymesterone, an anabolic steroid with the 17alpha-methyl,17beta-hydroxy group, has been developed as an oral formulation for therapeutic purposes. However, it is also used illegally in racehorses to enhance racing performance. In this study, we detected 9alpha-fluoro-17,17-dimethyl-18-norandrostane-4,13-dien-11beta-ol-3-one by gas chromatography/mass spectrometry (GC/MS), which has not been reported as a fluoxymesterone metabolite so far in horse. It was synthesized for use as a reference standard, and characterized on the basis of (1)H NMR and (13)C NMR spectra, as well as GC/MS EI mass spectra of TMS derivatives. It was excreted as the main metabolite in horse urine, and its reference standard could be synthesized easily. Therefore, this metabolite could be a useful target for a doping test of fluoxymesterone in racehorses. PMID:18614835

  8. The identification of synthetic organic pigments in modern paints and modern paintings using pyrolysis-gas chromatography-mass spectrometry.

    PubMed

    Russell, Joanna; Singer, Brian W; Perry, Justin J; Bacon, Anne

    2011-05-01

    A collection of more than 70 synthetic organic pigments were analysed using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). We report on the analysis of diketo-pyrrolo-pyrrole, isoindolinone and perylene pigments which are classes not previously reported as being analysed by this technique. We also report on a number of azo pigments (2-naphthol, naphthol AS, arylide, diarylide, benzimidazolone and disazo condensation pigments) and phthalocyanine pigments, the Py-GC-MS analysis of which has not been previously reported. The members of each class were found to fragment in a consistent way and the pyrolysis products are reported. The technique was successfully applied to the analysis of paints used by the artist Francis Bacon (1909-1992), to simultaneously identify synthetic organic pigments and synthetic binding media in two samples of paint taken from Bacon's studio and micro-samples taken from three of his paintings and one painting attributed to him. PMID:21416165

  9. Analytical strategies for characterizing organic paint media using gas chromatography/mass spectrometry.

    PubMed

    Colombini, Maria Perla; Andreotti, Alessia; Bonaduce, Ilaria; Modugno, Francesca; Ribechini, Erika

    2010-06-15

    Throughout history, artists have experimented with a variety of organic-based natural materials, using them as paint binders, varnishes, and ingredients for mordants in gildings. Artists often use many layers of paint to produce particular effects. How we see a painting is thus the final result of how this complex, highly heterogeneous, multimaterial, and multilayered structure interacts with light. The chemical characterization of the organic substances in paint materials is of great importance for artwork conservation because the organic components of the paint layers are particularly subject to degradation. In addition, understanding the organic content and makeup of paint materials allows us to differentiate between the painting techniques that have been used over history. Applying gas chromatography/mass spectrometry (GC/MS) analysis to microsamples of paint layers is widely recognized as the best approach for identifying organic materials, such as proteins, drying oils, waxes, terpenic resins, and polysaccharide gums. The method provides essential information for reconstructing artistic techniques, assessing the best conditions for long-term preservation, and planning restoration. In this Account, we summarize the more common approaches adopted in the study of the organic components of paint materials. Our progress in developing GC/MS analytical procedures in the field of cultural heritage is presented, focusing on problems that arise from (i) the presence of mixtures of many chemically complex and degraded materials, (ii) the interference of inorganic species, (iii) the small size of the samples, and (iv) the risk of contamination. We outline some critical aspects of the analytical strategy, such as the need to optimize specific wet-chemical sample pretreatments in order to separate the various components, hydrolyze macromolecular analytes, clean-up inorganic ions, and derivatize polar molecules for subsequent GC/MS separation and identification. We also discuss how to interpret the chromatographic data so as to be able to identify the materials. This identification is based on the presence of specific biomarkers (chemotaxonomy), on the evaluation of the overall chromatographic profile, or on the quantitative analysis of significant compounds. GC/MS-based analytical procedures have for 20 years provided important contributions to conservation science, but challenges and opportunities still coexist in the field of organic-based paint materials. We give selected examples and provide case studies showing how a better understanding of the chemical composition of organic paint materials and of their degradation pathways contribute to a better knowledge our cultural heritage, and to its preservation for future generations. PMID:20180544

  10. Authentication of Organically and Conventionally Grown Basils by Gas Chromatography/Mass Spectrometry Chemical Profiles

    PubMed Central

    Wang, Zhengfang; Chen, Pei; Yu, Liangli; Harrington, Peter de B.

    2013-01-01

    Basil plants cultivated by organic and conventional farming practices were accurately classified by pattern recognition of gas chromatography/mass spectrometry (GC/MS) data. A novel extraction procedure was devised to extract characteristic compounds from ground basil powders. Two in-house fuzzy classifiers, i.e., the fuzzy rule-building expert system (FuRES) and the fuzzy optimal associative memory (FOAM) for the first time, were used to build classification models. Two crisp classifiers, i.e., soft independent modeling by class analogy (SIMCA) and the partial least-squares discriminant analysis (PLS-DA), were used as control methods. Prior to data processing, baseline correction and retention time alignment were performed. Classifiers were built with the two-way data sets, the total ion chromatogram representation of data sets, and the total mass spectrum representation of data sets, separately. Bootstrapped Latin partition (BLP) was used as an unbiased evaluation of the classifiers. By using two-way data sets, average classification rates with FuRES, FOAM, SIMCA, and PLS-DA were 100 ± 0%, 94.4 ± 0.4%, 93.3 ± 0.4%, and 100 ± 0%, respectively, for 100 independent evaluations. The established classifiers were used to classify a new validation set collected 2.5 months later with no parametric changes except that the training set and validation set were individually mean-centered. For the new two-way validation set, classification rates with FuRES, FOAM, SIMCA, and PLS-DA were 100%, 83%, 97%, and 100%, respectively. Thereby, the GC/MS analysis was demonstrated as a viable approach for organic basil authentication. It is the first time that a FOAM has been applied to classification. A novel baseline correction method was used also for the first time. The FuRES and the FOAM are demonstrated as powerful tools for modeling and classifying GC/MS data of complex samples and the data pretreatments are demonstrated to be useful to improve the performance of classifiers. PMID:23398171

  11. 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

  12. Measuring the Composition and Stable-Isotope Labeling of Algal Biomass Carbohydrates via Gas Chromatography/Mass Spectrometry.

    PubMed

    McConnell, Brian O; Antoniewicz, Maciek R

    2016-05-01

    We have developed a method to measure carbohydrate composition and stable-isotope labeling in algal biomass using gas chromatography/mass spectrometry (GC/MS). The method consists of two-stage hydrochloric acid hydrolysis, followed by chemical derivatization of the released monomer sugars and quantification by GC/MS. Fully (13)C-labeled sugars are used as internal standards for composition analysis. This convenient, reliable, and accurate single-platform workflow offers advantages over existing methods and opens new opportunities to study carbohydrate metabolism of algae under autotrophic, mixotrophic, and heterotrophic conditions using metabolic flux analysis and isotopic tracers such as (2)H2O and (13)C-glucose. PMID:27042946

  13. Plasma metabolomic profiling of dairy cows affected with ketosis using gas chromatography/mass spectrometry

    PubMed Central

    2013-01-01

    Background Ketosis is an important problem for dairy cows` production performance. However, it is still little known about plasma metabolomics details of dairy ketosis. Results A gas chromatography/mass spectrometry (GC/MS) technique was used to investigate plasma metabolic differences in cows that had clinical ketosis (CK, n=22), subclinical ketosis (SK, n=32), or were clinically normal controls (NC, n=22). The endogenous plasma metabolome was measured by chemical derivatization followed by GC/MS, which led to the detection of 267 variables. A two-sample t-test of 30, 32, and 13 metabolites showed statistically significant differences between SK and NC, CK and NC, and CK and SK, respectively. Orthogonal signal correction-partial least-square discriminant analysis (OPLS-DA) revealed that the metabolic patterns of both CK and SK were mostly similar, with the exception of a few differences. The development of CK and SK involved disturbances in many metabolic pathways, mainly including fatty acid metabolism, amino acid metabolism, glycolysis, gluconeogenesis, and the pentose phosphate pathway. A diagnostic model arbitrary two groups was constructed using OPLS-DA and receiver–operator characteristic curves (ROC). Multivariate statistical diagnostics yielded the 19 potential biomarkers for SK and NC, 31 for CK and NC, and 8 for CK and SK with area under the curve (AUC) values. Our results showed the potential biomarkers from CK, SK, and NC, including carbohydrates, fatty acids, amino acids, even sitosterol and vitamin E isomers, etc. 2-piperidinecarboxylic acid and cis-9-hexadecenoic acid were closely associated with metabolic perturbations in ketosis as Glc, BHBA and NEFA for dealing with metabolic disturbances of ketosis in clinical practice. However, further research is needed to explain changes of 2,3,4-trihydroxybutyric acid, 3,4-dihydroxybutyric acid, α-aminobutyric acid, methylmalonic acid, sitosterol and α-tocopherol in CK and SK, and to reveal differences between CK and SK. Conclusion Our study shows that some new biomarkers of ketosis from plasma may find new metabolic changes to have clinically new utility and significance in diagnosis, prognosis, and prevention of ketosis in the future. PMID:24070026

  14. A gas chromatography-mass spectrometry-based metabolomic approach for the characterization of goat milk compared with cow milk.

    PubMed

    Scano, Paola; Murgia, Antonio; Pirisi, Filippo M; Caboni, Pierluigi

    2014-10-01

    In this work, the polar metabolite pool of commercial caprine milk was studied by gas chromatography-mass spectrometry and multivariate statistical data analysis. Experimental data were compared with those of cow milk and the discriminant analysis correctly classified milk. By the same means, differences due to heat treatments (UHT or pasteurization) on milk samples were also investigated. Results of the 2 discriminant analyses were combined, with the aim of finding the discriminant metabolites unique for each class and shared by 2 classes. Valine and glycine were specific to goat milk, talose and malic acid to cow milk, and hydroxyglutaric acid to pasteurized samples. Glucose and fructose were shared by cow milk and UHT-treated samples, whereas ribose was shared by pasteurized and goat milk. Other discriminant variables were not attributed to specific metabolites. Furthermore, with the aim to reduce food fraud, the issue of adulteration of caprine milk by addition of cheaper bovine milk has been also addressed. To this goal, mixtures of goat and cow milk were prepared by adding the latter in a range from 0 to 100% (vol/vol) and studied by multivariate regression analysis. The error in the level of cow milk detectable was approximately 5%. These overall results demonstrated that, through the combined approach of gas chromatography-mass spectrometry and multivariate statistical data analysis, we were able to discriminate between milk typologies on the basis of their polar metabolite profiles and to propose a new analytical method to easily discover food fraud and to protect goat milk uniqueness. The use of appropriate visualization tools improved the interpretation of multivariate model results. PMID:25108860

  15. Determination of nonsteroidal anti-inflammatory drugs, caffeine, and triclosan in wastewater by gas chromatography-mass spectrometry.

    PubMed

    Thomas, Paul M; Foster, Gregory D

    2004-01-01

    Pharmaceuticals are a class of chemicals whose fate in the environment has received increasing attention in the past few years. A quantitative method was developed for the determination of acidic pharmaceuticals (ibuprofen, naproxen, ketoprofen, mefenamic acid, and diclofenac), caffeine and the antibacterial triclosan in wastewater effluent. The compounds were extracted from wastewater samples on Waters Oasis HLB solid-phase extraction columns, derivatized with N,O-bis [Trimethylsilyl] trifluoroacetamide (BSTFA) and analyzed using gas chromatography-mass spectrometry. Estimated method detection limits ranged from 6 to 45 ng/L based on replicate analyses (n = 10). This method was applied to the analysis of effluent from a wastewater treatment plant and compounds were detected at concentrations of 18-72 ng/L. PMID:15332662

  16. Pyrolysis-gas chromatography/mass spectrometry analyses of biological particulates collected during recent space shuttle missions

    NASA Technical Reports Server (NTRS)

    Matney, M. L.; Limero, T. F.; James, J. T.

    1994-01-01

    Biological particulates collected on air filters during shuttle missions (STS-40 and STS-42) were identified using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). A method was developed for identifying the atmospheric particles and their sources through the analysis of standard materials and the selection of "marker" compounds specific to the particle type. Pyrolysis spectra of biological standards were compared with those of airborne particles collected during two space shuttle missions; marker compounds present in the shuttle particle spectra were matched with those of the standards to identify the source of particles. Particles of 0,5--1-mm diameter and weighing as little as 40 micrograms could be identified using this technique. The Py-GC/MS method identified rat food and soilless plant-growth media as two sources of particles collected from the shuttle atmosphere during flight.

  17. Accelerated solvent extraction and gas chromatography/mass spectrometry for determination of polycyclic aromatic hydrocarbons in smoked food samples.

    PubMed

    Wang, G; Lee, A S; Lewis, M; Kamath, B; Archer, R K

    1999-03-01

    Accelerated solvent extraction (ASE) is a new sample extraction method offering a number of advantages such as low pe -extraction cost, reduced solvent and time consumption, and simplified extraction protocols. In this study, the ASE method was applied to the extraction of polycyclic aromatic hydrocarbons (PAHs) from biological samples. For recovery studies, fish tissues and ground pork were used as sample matrices. Sample aliquots fortified with 16 PAHs were extracted by ASE, and the extracts were treated with sulfuric acid and Florisil, followed by gas chromatography-mass spectrometry analysis. The PAH recoveries by the ASE method were found to be comparable with or better than those by Soxhlet extraction. The extraction and quantitation method was then applied to the determination of PAHs in several smoked meat samples obtained from a local market. Up to 12 PAHs were found to be present at concentrations ranging from 3 to 52 ng/g wet sample. PMID:10552416

  18. 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....

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

    PubMed

    Hilkert; Douthitt; Schlter; 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

  20. Sensory screening for large-format natural corks by "dry soak" testing and its correlation to headspace solid-phase microextraction (SPME) gas chromatography/mass spectrometry (GC/MS) releasable trichloroanisole (TCA) analysis.

    PubMed

    Macku, Carlos; Gonzalez, Lesa; Schleussner, Christiane; Mesquita, Ana Cristina; Herwatt, James W; Kirch, Leonard C; Schwartz, Rob J

    2009-09-01

    Large-format natural corks were individually screened for trichloroanisole (TCA) taint and other non-characteristic cork odors by smelling the high relative humidity headspace of the jarred closure during expert panel sensory sessions. The method was coined "dry soak sensory screening". Out of a population of 2296 corks, 138 specimens [6% of the total population (TP)] were retained because of unusual odors, ranging from mild to severe. All retained corks were analyzed for releasable TCA (RTCA) by the solid-phase microextraction (SPME) gas chromatography/mass spectrometry (GC/MS) technique. Results indicated that 30 corks (1.3% TP) had concentrations between 1.0 and 5.0 ppt. Most of these corks had non-typical TCA odors described as ashtray, musty, moldy, dirty, and wet cardboard. A total of 13 retained corks (0.57% TP) had RTCA values higher than 5.0 ppt, mostly displaying the typical TCA odor. Dry soak screening has been determined to be a clean, fast, and most importantly, a nondestructive method ideal for screening large-format natural corks with off odors. PMID:19722710

  1. 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.

  2. Analysis of enantiomeric and non-enantiomeric monoterpenes in plant emissions using portable dynamic air sampling/solid-phase microextraction (PDAS-SPME) and chiral gas chromatography/mass spectrometry

    NASA Astrophysics Data System (ADS)

    Yassaa, Noureddine; Williams, Jonathan

    A portable dynamic air sampler (PDAS) using a porous polymer solid-phase microextraction (SPME) fibre has been validated for the determination of biogenic enantiomeric and non-enantiomeric monoterpenes in air. These compounds were adsorbed in the field, and then thermally desorbed at 250 °C in a gas chromatograph injector port connected via a β-cyclodextrin capillary separating column to a mass spectrometer. The optimized method has been applied for investigating the emissions of enantiomeric monoterpenes from Pseudotsuga menziesii (Douglas-fir), Rosmarinus officinalis (Rosemary) and Lavandula lanata (Lavender) which were selected as representative of coniferous trees and aromatic plants, respectively. The enantiomers of α-pinene, sabinene, camphene, δ-3-carene, β-pinene, limonene, β-phellandrene, 4-carene and camphor were successfully determined in the emissions from the three plants. While Douglas-fir showed a strong predominance toward (-)-enantiomers, Rosemary and Lavender demonstrated a large variation in enantiomeric distribution of monoterpenes. The simplicity, rapidity and sensitivity of dynamic sampling with porous polymer coated SPME fibres coupled to chiral capillary gas chromatography/mass spectrometry (GC/MS) makes this method potentially useful for in-field investigations of atmosphere-biosphere interactions and studies of optically explicit atmospheric chemistry.

  3. The use of gas chromatography-mass spectrometry/combustion/isotope ratio mass spectrometry to demonstrate progesterone treatment in bovines.

    PubMed

    Janssens, Geert; Mangelinckx, Sven; Courtheyn, Dirk; De Kimpe, Norbert; Matthijs, Bert; Le Bizec, Bruno

    2016-06-01

    Currently, no analytical method is available to demonstrate progesterone administration in biological samples collected in rearing animals, and therefore, tracking the abuse of this popular growth promoter is arduous. In this study, a method is presented to reveal progesterone (PG) treatment on the basis of carbon isotope measurement of 5β-pregnane-3α, 20α-diol (BAA-PD), a major PG metabolite excreted in bovine urine, by gas chromatography-mass spectrometry/combustion/isotope ratio mass spectrometry (GC-MS/C/IRMS). 5-Androstene-3β,17α-diol (AEdiol) is used as endogenous reference compound. Intermediate precisions (n=11) of 0.56‰ and 0.68‰ have been determined for AEdiol and BAA-PD, respectively. The analytical method was used for the very first time to successfully differentiate urine samples collected in treated and untreated animals. PMID:27157423

  4. [Differentiation of ballpoint pen inks by thermodesorption and gas chromatography-mass spectrometry].

    PubMed

    Bügler, Jürgen; Buchner, Hans; Dallmayer, Anton

    2004-01-01

    Differentiation and classification of ink entries with dated samples of a reference collection are important aspects in the examination of questioned documents. Classification of writing inks is presently achieved by analysis of dyes and colorants contained in the ink. This technique has its limitations in newly developed ink formulations with identical dye composition but differing in their solvents and binder resins. This paper introduces a method for the determination of solvents and binder resins of an ink sample directly from paper without sample preparation. This aim is accomplished by thermodesorption of the sample followed by gas chromatography/mass spectroscopy. The method was tested on numerous samples of ballpoint pen inks, which were subsequently grouped into several solvent and resin subgroups. A case study shows the applicability of the newly developed method. PMID:15666970

  5. Biosynthesis of Gold Nanoparticles and Identification of Capping Agent Using Gas Chromatography-Mass Spectrometry and Matrix Assisted Laser Desorption Ionization-Mass Spectrometry.

    PubMed

    Karthick, V; Kumar, V Ganesh; Dhas, T Stalin; Govindaraju, K; Sinha, Sweta; Singaravelu, G

    2015-06-01

    In the present study, gold nanoparticles (AuNPs) were synthesized using leaf extract of Syzygium jambolanum and capping agent has been explored. The synthesized AuNPs have been characterized using UV-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscopy (HRTEM) and atomic force microscopic (AFM) analysis. The AuNPs show intense surface plasmon resonance (SPR) band at 528 nm and were found to be spherical and hexagonal in shape with particle size ranging from 20-30 nm. Transmission electron microscopy and atomic force microscopy were used to analyze the surface morphology of synthesized AuNPs. The capping ligand has been evaluated using matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS) and gas chromatography-mass spectrometry (GC-MS) analysis. PMID:26369012

  6. An optimized electrochemistry-liquid chromatography-mass spectrometry method for studying guanosine oxidation

    PubMed Central

    Erb, Robert; Plattner, Sabine; Pitterl, Florian; Brouwer, Hendrik-Jan; Oberacher, Herbert

    2012-01-01

    Oxidative stress can disrupt the integrity of genetic material. Due to its importance in the pathogenesis of different kinds of disease, including neurodegenerative disease, cardiovascular disease and cancer, major efforts are put into the elucidation of mechanisms involved. Herein, the combination of electrochemistry/liquid chromatography/mass spectrometry (EC/LC/MS) is presented as convenient, fast and simple method to study nucleic acids oxidation. Guanosine was selected as test compound. 8-Hydroxyguanosine and (guanosine-H)2 were identified as primary oxidation products. Oxidation was accomplished in an electrochemical thin-layer cell integrated in the flow path of the autosampler of the chromatographic system. The reaction mixture was separated and mass analyzed by LC/MS. The use of LC was found to be particularly beneficial to resolve isobaric oxidation products. Another advantage of the setup used was the ability to decouple the electrochemical cell and the electrospray ionization source from each other eliminating any kind of cell potential interaction. Separation of EC from LC/MS, furthermore, facilitates method optimization. Experimental parameters were optimized for both techniques independently. Highest yields and best detectability of oxidation products were obtained with 10 mM ammonium formate at physiological pH delivered at a flow rate of 2.5-5 μL/min through the electrochemical cell. PMID:22451054

  7. Identification of tartary buckwheat tea aroma compounds with gas chromatography-mass spectrometry.

    PubMed

    Qin, Peiyou; Ma, Tingjun; Wu, Li; Shan, Fang; Ren, Guixing

    2011-08-01

    Tartary buckwheat tea, which is an important and healthy product, has a distinct malty aroma. However, its characteristic aroma compounds have not been elucidated. The aims of present study were identification and quantification of its aroma compounds. The analyses were performed by gas chromatography-mass spectrometry (GC-MS) after 3 different isolation techniques. Seventy-seven compounds were identified. Among these compounds, 35 were quantified by available standards. The compounds with a high probability of contribution to the tartary buckwheat tea aroma (OAV ≥ 10) were as follows: 2,5-dimethyl-4-hydroxy-3(2H)-furanone, nonanal, 2,3-diethyl-5-methylpyrazine, benzeneacetaldehyde, maltol, 2,5-dimethylpyrazine, 2-ethyl-5-methylpyrazine, trimethylpyrazine. Some nutritional and bioactive compounds were also identified in this study, such as linoleic acid, niacin, vanillic acid, 7-hydroxycoumarin, butylated hydroxytoluene. Practical Application: Tartary buckwheat, one type of buckwheat, has gained much attention from nutritionists and medical doctors in recent years. It is rich in rutin, quercetin, and other nutrients that are good for health. Tartary buckwheat-based product such as tartary buckwheat tea is an important and popular healthy product in China, Japan,South Korea, European countries as well as in American countries. It has a distinct malty aroma. The present study first identified and quantified of its aroma compounds. The results will draw attention to other researchers in food flavor and buckwheat filed. PMID:22417522

  8. Headspace gas chromatography-mass spectrometry of volatile compounds in murici (Byrsonima crassifolia l. Rich).

    PubMed

    Alves, G L; Franco, M R B

    2003-01-24

    Northern and Northeastern Brazil have a natural diversity of fruits, many of which are considered exotic, presenting different flavors and aromas. The enormous diversity of fruits represents a promising area for research on aromas. There is also a great potential for the manufacture of juices, desserts or other processed products. Murici is a typical fruit from these regions presenting a different flavor, reminiscent of that of cheese. This fruit is consumed mainly as juice, ice cream or as liquor, greatly appreciated by the local population. Headspace volatile compounds of three lots of the fruit from Cear (Fortaleza) were collected by suction on Porapak Q for 2 h and desorbed with 300 microl of acetone. The isolated volatile compounds were separated by high resolution GC. Forty-six volatile compounds were detected, of which 41 were identified by gas chromatography-mass spectrometry and Kovats indices. The most abundant compounds were ethanol (28.3%) and ethyl hexanoate (25.1%). Butanoic acid (5.1%), hexanoic acid (5.1%) and methyl butyrate (2.8%) were also detected in the headspace of the fruit and confirm its unusual cheese aroma. PMID:12580497

  9. The gas chromatography/mass spectrometry can be used for dose estimation in irradiated pork

    NASA Astrophysics Data System (ADS)

    D'Oca, M. C.; Bartolotta, A.; Cammilleri, M. C.; Giuffrida, S. A.; Parlato, A.; Di Noto, A. M.; Caracappa, S.

    2009-07-01

    Food safety can be improved using ionizing radiation to reduce food spoilage and to extend its shelf life. The gas chromatography/mass spectrometry (GC/MS) has been validated by the European Community as a powerful method to identify irradiated food containing fat. The preliminary goals of our research were: (i) to set up this method, based on the detection of radiation induced 2-dodecylcyclobutanones (2-DCB) in pork muscle samples and (ii) to check the microbiological efficacy of the treatment. The main objective was to render the GC/MS a quantitative technique for dose estimation, through the measurement of the 2-DCB concentration in the irradiated sample. Our results show that the reduction of the microbial population is substantially reduced even at 2 kGy, and that a clear identification of irradiated samples can be achieved also one month after irradiation at 2 kGy in frozen-stored samples. The 2-DCB concentration showed a linear dependence on dose in the range 1-10 kGy, no matter the origin of the sample; a unique calibration function was obtained, that allowed dose estimation in irradiated pork samples. A retrospective evaluation on the quality of the treatment could be carried out this way.

  10. Pharmaceuticals in grocery market fish fillets by gas chromatography-mass spectrometry.

    PubMed

    Mottaleb, Musavvir Arafat; Stowe, Carly; Johnson, Daniel R; Meziani, Mohammed J; Mottaleb, M Abdul

    2016-01-01

    Occurrences of pharmaceuticals are evident in aquatic organisms. A reproducible gas chromatography-mass spectrometry (GC-MS) method using selected ion monitoring (SIM) has been used to determine the anti-histamine diphenhydramine (DPH), anti-anxiety diazepam (DZP), anti-seizure carbamazepine (CZP) drugs and their metabolites in grocery stores fish that were homogenized, extracted, pre-concentrated, cleaned up, and examined. Identifications of the compounds in extracts were obtained by comparing similar mass spectral features and retention properties with standards. Among nine frequently detected drugs, only DPH and DZP were observed and ranged from 0.61 to 6.21 and 1.99 to 16.57 ng/g, respectively, in fourteen fish species. These concentration values were lower than the environmental fish. Mean spike recoveries of analytes exceeded 75% with relative standard deviations (RSD)<10%. The statistically-derived method detection limits (MDLs) for nine compounds ranged from 0.13 to 5.56 ng/g. Average surrogate recoveries were 80-85% with 4-9% RSD. PMID:26213006

  11. Performance of an improved monodisperse aerosol generation interface for liquid chromatography/mass spectrometry

    SciTech Connect

    Winkler, P.C.; Perkins, D.D.; Williams, W.K.; Browner, R.F.

    1988-03-01

    An improved monodisperse aerosol generation interface for liquid chromatography/mass spectrometry interfacing (MAG-IC-LC/MS) is described. The interface has an aerodynamically superior momentum separator, which results in decreased analyte loss in passing through the interface. The interface is shown to perform well with a quadrupole mass spectrometer, in addition to earlier studies with a magnetic sector instrument. A new method of forming aerosol has been developed, which reduces the dead volume significantly over earlier designs. The performance of the interface has been evaluated by studying its capabilities for (1) generating electron impact spectra of searchable quality for selected compounds of interest, (2) operating with typical liquid chromatographic separation conditions, including reverse phase and gradient elution, and (3) providing low detection limits for both full scan and selective ion monitoring detection of a range of compounds. Studies include identification of the components of a mixture of cis and trans isomers of the thermally labile compound retinol (vitamin A) acetate. Full scan (m/z 80-350) electron impact spectra were readily obtained with 50-ng injection on-column. Detection limits for this compound were 10 ng full scan and 1 ng with selected ion monitoring. Identification of a free (nonderivatized) fatty acid mixture was also readily obtained, using a reversed-phase separation in gradient mode.

  12. Chemical Discrimination in Turbulent Gas Mixtures with MOX Sensors Validated by Gas Chromatography-Mass Spectrometry

    PubMed Central

    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

  13. Determination of steroidal estrogens in flushed dairy manure wastewater by gas chromatography-mass spectrometry.

    PubMed

    Hanselman, Travis A; Graetz, Donald A; Wilkie, Ann C; Szabo, Nancy J; Diaz, Carolyn S

    2006-01-01

    There is a critical need to accurately measure the concentrations of natural steroidal estrogens in flushed dairy manure wastewater (FDMW) to assess any potential risk of waterway contamination resulting from land application. Estrogens are a concern because low concentrations (10-100 ng L-1) in water can adversely affect aquatic vertebrate species such as fish, turtles, and frogs by disrupting the normal function of their endocrine systems. The objective of this study was to develop a sample preparation method that permits the quantification of four natural steroidal estrogens (17alpha-estradiol, 17beta-estradiol, estrone, and estriol) in FDMW by gas chromatography-mass spectrometry (GC-MS). Solid-phase extraction with graphitized carbon black was used for the bulk extraction of estrogens from FDMW and additional sample purification was accomplished with C-18. The sample preparation method allowed estrogens to be detected accurately by GC-MS in FDMW. Spiked recovery experiments indicated that the method is satisfactory for measuring the estrogens of interest in FDMW with average recovery of >90%. As expected in FDMW, characterization of the estrogen profile revealed a large abundance of 17alpha-estradiol relative to 17beta-estradiol and estrone. Estriol was not detected in FDMW. The methodology developed in this research helps provide an analytical foundation for the quantification of steroidal estrogens in FDMW by GC-MS. PMID:16585610

  14. Determination of ortho-phenylphenol in human urine by gas chromatography-mass spectrometry.

    PubMed

    Bartels, M J; Brzak, K A; Bormett, G A

    1997-12-01

    A sensitive gas chromatographic-mass spectrometric method was developed to quantitate total o-phenylphenol (OPP) (free plus conjugates) in human urine. Conjugates of OPP were acid-hydrolyzed to free OPP, derivatized to the pentafluorobenzoyl ester derivative and analyzed via negative-ion chemical ionization gas chromatography-mass spectrometry. Two stable isotope analogs of OPP were shown to be suitable as internal standards for this method (D2-phenol ring, 13C6-phenyl ring). A synthetic method is presented for the preparation of the D2-OPP internal standard. The 13C6-OPP analog was also shown to be useful as an alternate test material for laboratory-based exposure studies. The limit of quantitation for this method was 1 ng OPP/ml urine. Calibration curves were linear for the analyte over the concentration range of 0.5-1117 ng OPP/ml urine. Relative recovery of OPP from urine ranged from 97.0 to 104.7%. Low levels of OPP (mean=6+/-7 ng/ml; n=22) were found in control human urine samples. The method was validated with urine samples obtained from human volunteers undergoing a dermal exposure study with 12C-/13C6-/14C-OPP. This method was developed to aid in assessments of human exposure to OPP during a variety of uses of the compound. PMID:9448066

  15. Determination of Menthol in Plasma and Urine by Gas Chromatography/Mass Spectrometry (GC/MS).

    PubMed

    Peat, Judy; Frazee, Clint; Kearns, Gregory; Garg, Uttam

    2016-01-01

    Menthol, a monoterpene, is a principal component of peppermint oil and is used extensively in consumer products as a flavoring aid. It is also commonly used medicinally as a topical skin coolant; to treat inflammation of the mucous membranes, digestive problems, and irritable bowel syndrome (IBS); and in preventing spasms during endoscopy and for its spasmolytic effect on the smooth muscle of the gastrointestinal tract. Menthol has a half life of 3-6 h and is rapidly metabolized to menthol glucuronide which is detectable in urine and serum following menthol use. We describe a method for the determination of total menthol in human plasma and urine using liquid/liquid extraction, gas chromatography/mass spectrometry (GC/MS) in selected ion monitoring mode and menthol-d4 as the internal standard. Controls are prepared with menthol glucuronide and all samples undergo enzymatic hydrolysis for the quantification of total menthol. The method has a linear range of 5-1000 ng/mL, and coefficient of variation <10%. PMID:26660189

  16. 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

  17. Gas chromatography mass spectrometry based metabolic profiling reveals biomarkers involved in rice-gall midge interactions.

    PubMed

    Agarrwal, Ruchi; Bentur, Jagadish Sanmallappa; Nair, Suresh

    2014-09-01

    The Asian rice gall midge (Orseolia oryzae Wood-Mason) is a serious pest of rice that causes huge loss in yield. While feeding inside the susceptible host, maggots secrete substances that facilitate the formation of a hollow tube-like structure called gall and prevent panicle formation. The present investigation was carried out to get an account of biochemical changes occurring in the rice plant upon gall midge feeding. Metabolic profiling of host tissues from three rice varieties, namely, TN1, Kavya, and RP2068, exposed to gall midge biotype 1 (GMB1), was carried out using gas chromatography mass spectrometry (GC-MS). TN1 and GMB1 represented compatible interaction, while Kavya and GMB1 as well as RP2068 and GMB1 represented incompatible interactions. The current study identified several metabolites that could be grouped as resistance, susceptibility, infestation, and host features based on their relative abundance. These may be regarded as biomarkers for insect-plant interaction in general and rice-gall midge interaction in particular. PMID:25059749

  18. Systematic error in gas chromatography-mass spectrometry-based quantification of hydrolyzed urinary steroids.

    PubMed

    Moon, Ju-Yeon; Ha, Young Wan; Moon, Myeong Hee; Chung, Bong Chul; Choi, Man Ho

    2010-02-01

    Gas chromatography-mass spectrometry-based metabolite profiling can lead to an understanding of various disease mechanisms as well as to identifying new diagnostic biomarkers by comparing the metabolites related in quantification. However, the unexpected transformation of urinary steroids during enzymatic hydrolysis with Helix pomatia could result in an underestimation or overestimation of their concentrations. A comparison of beta-glucuronidase extracted from Escherichia coli revealed 18 conversions of 84 steroids tested as an unexpected transformation under hydrolysis with beta-glucuronidase/arylsulfatase extracted from Helix pomatia. In addition to the conversion of 3beta-hydroxy-5-ene steroids into 3-oxo-4-ene steroids, which has been reported, the transformation of 3beta-hydroxy-5alpha-reduced and 3beta-hydroxy-5beta-reduced steroids to 3-oxo-5alpha-reduced and 3-oxo-5beta-reduced steroids, respectively, was newly observed. The formation of by-products was in proportion to the concentration of substrates becoming saturated against the enzyme. The substances belonging to these three steroid groups were undetectable at low concentrations, whereas the corresponding by-products were overestimated. These results indicate that the systematic error in the quantification of urinary steroids hydrolyzed with Helix pomatia can lead to a misreading of the clinical implications. All these hydrolysis procedures are suitable for study purposes, and the information can help prevent false evaluations of urinary steroids in clinical studies. PMID:20086107

  19. Identification of monoacylglycerol regio-isomers by gas chromatography-mass spectrometry.

    PubMed

    Destaillats, Frdric; Cruz-Hernandez, Cristina; Nagy, Kornl; Dionisi, Fabiola

    2010-02-26

    Monoacylglycerols (MAGs) are lipids found in trace amounts in plants and animal tissues. While they are widely used in various industrial applications, accurate determination of the regio-specific distribution is hindered by the lack of stable, commercially available standards. Indeed, unsaturated beta-MAG (or Sn-2 MAG) readily undergoes isomerization into alpha-MAG (acyl chain is attached to the Sn-1 or the Sn-3 position). In the present study, we describe structural elucidation of alpha- and beta-regio-isomers of monopalmitoyl-glycerol (MAG C16:0) as model compounds in their silylated forms using gas chromatography-mass spectrometry (GC-MS) with electronic impact (EI) ionization. MS fragmentation of alpha-MAG C16:0 is characterized by the loss of methylene(trimethylsilyl)oxonium (103 amu) and the consecutive loss of acyl chain yielding a fragment ion at m/z 205. The fragmentation pattern of beta-MAG C16:0 shows a series of diagnostic fragments at m/z 218, 203, 191 and 103 that are not formed from the alpha-isomer and hereby enable reliable distinction of these regio-isomers. Possible fragmentation scenarios are postulated to explain the formation of these marker ions, which were also applied to characterize the regio-isomer composition of a complex mixture of MAG sample containing n-3 long-chain polyunsaturated fatty acids. PMID:20097347

  20. [Determination of alditols in foods by ion chromatography-mass spectrometry].

    PubMed

    Zhou, Hongbin; Xiong, Zhiyu; Li, Ping; Li, Jing; Sun, Li; Zhao, Yunxia

    2013-11-01

    A method for the determination of alditols in foods by ion chromatography-mass spectrometry (IC-MS) has been developed. The samples were extracted and cleaned up with the solid phase extraction (SPE). Then, the ion chromatographic separation was performed on a CarboPar MA1 column. The alditols were determined by MS with the selected ion monitoring (SIM) mode and quantified by the external standard method. The calibration curves showed good linearity in the certain ranges with the correlation coefficients (R2) greater than 0.99. The limits of quantification (S/N = 10) of erythritol, xylitol, D-sorbitol, D-mannitol, lactitol, maltitol were 0.98, 1.99, 2.24, 5.92, 13.56, 13.21 mg/kg and the limits of detection (S/N = 3) were 0.28, 0.59, 0.71, 1.74, 4.14, 4.03 mg/kg, respectively. The spiked recoveries of the alditols in the foods at different levels were in the range of 82.5%-108.0% with the relative standard deviations (RSDs) of 1.5%-7.6%. The sensitivity, accuracy and precision of the method meet the technical standards of the determination. The method can be applied to the determination of alditols in foods. PMID:24558846

  1. Determination of phthalate esters in teas and tea infusions by gas chromatography-mass spectrometry.

    PubMed

    Du, Liping; Ma, Lijuan; Qiao, Yang; Lu, Yan; Xiao, Dongguang

    2016-04-15

    Phthalate esters (PAEs), a group of environmental pollutants which are carcinogenic to human body, have been detected in teas. In this work, five PAEs in teas and tea infusions were quantitatively determined by a modified simultaneous distillation extraction (SDE) coupled with gas chromatography-mass spectrometry. After the optimization of SDE, the proposed method afforded a wide range of linearity and high linear regression coefficients with the limits of detection range of 0.24-3.72 μg/kg. The average recoveries were 79.83-116.67% for tea samples and 78.22-101.64% for tea infusions with all the relative standard deviations below 20%. The total content of five PAEs in teas was 1.135-3.734 mg/kg and the total dissolving ratio of five PAEs from tea to infusion was 19.05-28.07% for the selected tea samples. The risk assessment result of all the selected tea samples demonstrated that the population with the habit of drinking tea won't cause risk to human health. PMID:26675858

  2. 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 μg 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

  3. 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.

  4. Methods of Analysis by the U.S. Geological Survey National Water Quality Laboratory - Determination of Wastewater Compounds by Polystyrene-Divinylbenzene Solid-Phase Extraction and Capillary-Column Gas Chromatography/Mass Spectrometry

    USGS Publications Warehouse

    Zaugg, Steven D.; Smith, Steven G.; Schroeder, Michael P.; Barber, Larry B.; Burkhardt, Mark R.

    2002-01-01

    A method for the determination of 67 compounds typically found in domestic and industrial wastewater is described. The method was developed in response to increasing concern over the impact of endocrine-disrupting chemicals in wastewater on aquatic organisms. This method also may be useful for evaluating the impact of combined sanitary and storm-sewer overflow on the water quality of urban streams. The method focuses on the determination of compounds that are an indicator of wastewater or that have been chosen on the basis of their endocrine-disrupting potential or toxicity. These compounds include the alkylphenol ethoxylate nonionic surfactants and their degradates, food additives, fragrances, antioxidants, flame retardants, plasticizers, industrial solvents, disinfectants, fecal sterols, polycyclicaromatic hydrocarbons, and high-use domestic pesticides. Water samples are filtered to remove suspended particulate matter and then are extracted by vacuum through disposable solid-phase cartridges that contain polystyrene-divinylbenzene resin. Cartridges are dried with nitrogen gas, and then sorbed compounds are eluted with dichloromethane-diethyl ether (4:1) and determined by capillary-column gas chromatography/mass spectrometry. Recoveries in reagent-water samples fortified at 4 micrograms per liter averaged 74 percent ? 7 percent relative standard deviation for all method compounds. Initial method detection limits for single-component compounds (excluding hormones and sterols) averaged 0.15 microgram per liter. Samples are preserved by filtration, the addition of 60 grams NaCl, and storage at 4 degrees Celsius. The laboratory has established a sample-holding time (prior to sample extraction) of 14 days from the date of sample collection until a statistically accepted method can be used to determine the effectiveness of these sample-preservation procedures.

  5. 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 μM) at 4 h (5–125 mg/kg) and 1 h (250 mg/kg) after dosing, but levels quickly declined to <0.1 μM by 12 h in all the groups. In contrast, strikingly high concentrations of DACT (1.5–50 μM), 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

  6. Doping control analysis of TB-500, a synthetic version of an active region of thymosin β₄, in equine urine and plasma by liquid chromatography-mass spectrometry.

    PubMed

    Ho, Emmie N M; Kwok, W H; Lau, M Y; Wong, April S Y; Wan, Terence S M; Lam, Kenneth K H; Schiff, Peter J; Stewart, Brian D

    2012-11-23

    A veterinary preparation known as TB-500 and containing a synthetic version of the naturally occurring peptide LKKTETQ has emerged. The peptide segment (17)LKKTETQ(23) is the active site within the protein thymosin β(4) responsible for actin binding, cell migration and wound healing. The key ingredient of TB-500 is the peptide LKKTETQ with artificial acetylation of the N-terminus. TB-500 is claimed to promote endothelial cell differentiation, angiogenesis in dermal tissues, keratinocyte migration, collagen deposition and decrease inflammation. In order to control the misuse of TB-500 in equine sports, a method to definitely identify its prior use in horses is required. This study describes a method for the simultaneous detection of N-acetylated LKKTETQ and its metabolites in equine urine and plasma samples. The possible metabolites of N-acetylated LKKTETQ were first identified from in vitro studies. The parent peptide and its metabolites were isolated from equine urine or plasma by solid-phase extraction using ion-exchange cartridges, and analysed by liquid chromatography-mass spectrometry (LC/MS). These analytes were identified according to their LC retention times and relative abundances of the major product ions. The peptide N-acetylated LKKTETQ could be detected and confirmed at 0.02 ng/mL in equine plasma and 0.01 ng/mL in equine urine. This method was successful in confirming the presence of N-acetylated LKKTETQ and its metabolites in equine urine and plasma collected from horses administered with a single dose of TB-500 (containing 10mg of N-acetylated LKKTETQ). To our knowledge, this is the first identification of TB-500 and its metabolites in post-administration samples from horses. PMID:23084823

  7. Metabolomic analysis of normal (C57BL/6J, 129S1/SvImJ) mice by gas chromatography-mass spectrometry: detection of strain and gender differences.

    PubMed

    Qiao, Qian; Li, Tonghua; Sun, Jiangming; Liu, Xiaoyan; Ren, Jianke; Fei, Jian

    2011-07-15

    Previous studies have shown that the C57 and 129 strains of mice display marked differences in behavioural performance, neuroanatomy, neurochemistry and synaptic plasticity. However, few metabolomic studies of their biofluids have been performed. As part of a series of metabolic phenotyping, the effects of gender and strain upon serum metabolite composition and variation are examined in this study using gas chromatography-mass spectrometry (GC-MS) in normal C57BL/6J and 129S1/SvImJ strains of mice. The 129S1/SvImJ strain is phenotypically distinct from the C57BL/6J strain and characteristic metabotypes are produced for both male and female mice of each strain. These data demonstrate that the C57BL/6J and 129S1/SvImJ strains of mice show a wide range of metabolic differences across glycine, serine and threonine metabolism; valine, leucine and isoleucine biosynthesis; and tricarboxylic acid cycle pathways. Remarkably, the concentration of glyceric acid in the 129S1/SvImJ strain is significantly increased compared to the C57BL/6J mouse strain, reflecting important considerations for studies that use the 129S1/SvImJ mouse as the human d-glycericaciduria model. We infer that a deficiency of d-glycerate kinase would explain such a glyceric acid accumulation in the 129S1/SvImJ strain. More importantly, this differential metabolite level data provide insight into specific metabolic pathways and lay the groundwork for integrated studies of the mouse models. PMID:21645764

  8. Dispersive liquid-liquid microextraction followed by microwave-assisted silylation and gas chromatography-mass spectrometry analysis for simultaneous trace quantification of bisphenol A and 13 ultraviolet filters in wastewaters.

    PubMed

    Cunha, S C; Pena, A; Fernandes, J O

    2015-10-01

    A novel multi-residue gas chromatography-mass spectrometry (GC-MS) method was validated for the simultaneous determination of trace levels (ng/L) of 13 UV-filters and bisphenol A (BPA) in wastewater samples. It was based on dispersive liquid-liquid microextraction (DLMME) followed by rapid microwave-assisted silylation of the analytes. Several parameters of both extraction and derivatization steps such as type of extractive and dispersive solvents, solvent volumes, pH, salt addition, time and power of microwave were evaluated to achieve the highest yield and to attain the lowest detection limits. Optimized DLLME consisted in the formation of a cloudy solution promoted by the fast addition to the sample (10mL) of a mixture of tetrachloroethylene (50μL, extraction solvent) in acetone (1mL, dispersive solvent). The sedimented phase obtained was evaporated and further silylated under the irradiation of 600W microwave for 5min, being the derivatization yields similar to those obtained after a conventional heating process for 30min at 75°C. Limits of detection and quantification of the method using real samples were 2ng/L and 10ng/L, respectively. Mean extraction efficiency of 82% for three concentrations were achieved, supporting the accuracy of the method. Intra-day and inter-day repeatability of measurements (expressed as relative standard deviation) were lower than 22%. The method was successfully applied to the determination of UV-filters and BPA in samples collected from 15 wastewater treatment plants (WWTPs) in Portugal. Eight analytes were detected, among which 2-hydroxy-4-methoxybenzophenone, 2-ethylhexyl-4-(dimethylamino)benzoate, octocrylene, and BPA were consistently found in the three seasons of collection. PMID:26341596

  9. On-line monitoring trihalomethanes in chlorinated water by membrane introduction-fast gas chromatography mass-spectrometry.

    PubMed

    Chang, C C; Her, G R

    2000-09-29

    An analytical method based on membrane introduction and fast gas chromatography-mass spectrometry (GC-MS) has been developed for the on-line monitoring of trihatomethanes (THMs) in chlorinated drinking water. The coupling of membrane introduction with fast GC-MS offers the advantage of membrane introduction as an on-line sampling device and fast GC-MS as a separation and identification method. While maintaining the on-line monitoring characteristic of traditional membrane introduction mass spectrometry (MIMS), the difficulty of distinguishing CHCl3 and CHBrCl2 in MIMS was overcome by rapid GC separation and MS analysis. Water permeated across the membrane affected the analysis of CHBr2Cl and CHBr3. A method based on controlling the injection temperature and injection time has been developed to overcome the moisture problem. This method is simple and less time consuming than the conventional moisture removing method. Under typical operating conditions, the sampling rate was about 20 samples h(-1) capable of on-line monitoring THMs in chlorinated drinking water. The detection limits of this system were found to be about 2 ppt, 4 ppt, 4 ppt, and 8 ppt for CHCl3 CHBrCl2, CHBr2Cl, and CHBr3, respectively. PMID:11043597

  10. Identification of n-Decane Oxidation Products in Corynebacterium Cultures by Combined Gas Chromatography-Mass Spectrometry

    PubMed Central

    Bacchin, Paolo; Robertiello, Andrea; Viglia, Aurelio

    1974-01-01

    The gas chromatography-mass spectrometry technique was employed to characterize n-decane oxidation products of Corynebacterium strains 7E1C and 269 (SNAM Progetti collection) after 73 h of incubation at 35 C. Corynebacterium 7E1C accumulated consistent amounts of esters of long chain acids with long chain alcohols, mainly decyldecanoate as well as products with mono- and diterminal carboxylic functions. Corynebacterium 269 yielded 1-decanol and 1-10 decanediol as principal oxidation products. PMID:4441062

  11. Comparison of the structures of humic substances from aquatic and terrestrial sources by pyrolysis gas chromatography-mass spectrometry

    NASA Astrophysics Data System (ADS)

    Wilson, M. A.; Philp, R. P.; Gillam, A. H.; Gilbert, T. D.; Tate, K. R.

    1983-03-01

    Four humic extracts isolated from terrestrial, mahne, plankton and freshwater sources have been investigated by pyrolysis-gas chromatography-mass spectrometry. The results show that substantial quantities of phenols (some not derived from lignin), pyrroles and nitrites (derived from proteins, nucleic acids or porphyrins) are decomposition products. Small amounts of furans (derived from carbohydrates) and unsaturated ketones (derived from polycarboxylic aliphatic acids) are also present. The results illustrate how parent material, transport factors and biological activity affect the composition of humic extracts.

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

    PubMed Central

    Arora, Pankaj Kumar

    2014-01-01

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

  13. Urine Mescaline Screening With a Biochip Array Immunoassay and Quantification by Gas Chromatography-Mass Spectrometry.

    PubMed

    Battal, Dilek; Barnes, Allan J; Castaneto, Marisol S; Martin, Thomas M; Klette, Kevin L; Huestis, Marilyn A

    2015-12-01

    Mescaline, the primary psychoactive chemical in peyote cactus, has been consumed for thousands of years in ancient religious ceremonies. The US military wanted to determine if mescaline intake was a problem for personnel readiness. Twenty thousand seventeen urine specimens negative for cannabinoids, cocaine, opiates, and amphetamines were tested for mescaline with the Randox Drugs of Abuse V (DOA-V) biochip array immunoassay at the manufacturer's recommended cutoff of 6 mcg/L. A sensitive and specific method for mescaline quantification in urine was developed and fully validated. Extracted analytes were derivatized with pentafluoropropionic anhydride and pentafluoropropanol and quantified by gas chromatography-mass spectrometry (GC/MS) with electron impact ionization. Standard curves, using linear least squares regression with 1/x weighting, were linear from 1 to 250 mcg/L with coefficients of determination >0.994. Intra- and inter-assay imprecision was <4.4 coefficient of variation (%CV), with accuracies >90.4%. Mean extraction efficiencies were >92.0% across the linear range. This fully validated method was applied for the confirmation of urinary mescaline in 526 presumptive-positive specimens and 198 randomly selected presumptive-negative specimens at the manufacturer's 6 mcg/L cutoff. No specimen confirmed positive at the GC/MS limit of quantification of 1 mcg/L. Results indicated that during this time frame, there was insufficient mescaline drug use in the military to warrant routine screening in the drug testing program. However, mescaline stability, although assessed, could have contributed to lower prevalence. We also present a validated GC/MS method for mescaline quantification in urine for reliable confirmation of suspected mescaline intake. PMID:25992796

  14. A Liquid Chromatography-Mass Spectrometry-Based Metabolome Database for Tomato1

    PubMed Central

    Moco, Sofia; Bino, Raoul J.; Vorst, Oscar; Verhoeven, Harrie A.; de Groot, Joost; van Beek, Teris A.; Vervoort, Jacques; de Vos, C.H. Ric

    2006-01-01

    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 α-tomatine were specifically present in the peel, while several other alkaloids and some particular phenylpropanoids were mainly present in the flesh tissue. PMID:16896233

  15. Postmortem interval estimation: a novel approach utilizing gas chromatography/mass spectrometry-based biochemical profiling.

    PubMed

    Kaszynski, Richard H; Nishiumi, Shin; Azuma, Takeshi; Yoshida, Masaru; Kondo, Takeshi; Takahashi, Motonori; Asano, Migiwa; Ueno, Yasuhiro

    2016-05-01

    While the molecular mechanisms underlying postmortem change have been exhaustively investigated, the establishment of an objective and reliable means for estimating postmortem interval (PMI) remains an elusive feat. In the present study, we exploit low molecular weight metabolites to estimate postmortem interval in mice. After sacrifice, serum and muscle samples were procured from C57BL/6J mice (n = 52) at seven predetermined postmortem intervals (0, 1, 3, 6, 12, 24, and 48 h). After extraction and isolation, low molecular weight metabolites were measured via gas chromatography/mass spectrometry (GC/MS) and examined via semi-quantification studies. Then, PMI prediction models were generated for each of the 175 and 163 metabolites identified in muscle and serum, respectively, using a non-linear least squares curve fitting program. A PMI estimation panel for muscle and serum was then erected which consisted of 17 (9.7 %) and 14 (8.5 %) of the best PMI biomarkers identified in muscle and serum profiles demonstrating statistically significant correlations between metabolite quantity and PMI. Using a single-blinded assessment, we carried out validation studies on the PMI estimation panels. Mean ± standard deviation for accuracy of muscle and serum PMI prediction panels was -0.27 ± 2.88 and -0.89 ± 2.31 h, respectively. Ultimately, these studies elucidate the utility of metabolomic profiling in PMI estimation and pave the path toward biochemical profiling studies involving human samples. PMID:26931122

  16. Thin layer chromatography convulsant screen extended by gas chromatography-mass spectrometry.

    PubMed

    Braselton, W Emmett; Johnson, Malgorzata

    2003-01-01

    Acute onset convulsive disorders in the canine may result from exposure to a variety of toxicants including strychnine, insecticides, metaldehyde, zinc phosphide, methylxanthines, drugs of abuse, bromethalin, and the tremorgenic mycotoxins (roquefortine and penitrem A). Although several of the above can be identified in a single gas chromatography-mass spectrometry (GC-MS) screen most have to be determined by separate tests. This report describes a modification of the strychnine extraction procedure, which allows thin layer chromatographic (TLC) identification of strychnine, bromethalin, roquefortine, and penitrem A in suspect baits, stomach contents or vomitus, and extends the identification to a wide variety of drugs, pesticides, and environmental contaminants by GC-MS. Samples were mixed with base, extracted into CH2Cl2 and the organic fraction back-extracted with acid. The organic fraction (neutrals) was purified by gel permeation chromatography (GPC) and analyzed by TLC to determine penitrem A and bromethalin. The acidic aqueous fraction was adjusted to pH > 9 and extracted into CH2Cl2. The resulting CH2Cl2 layer (bases) was then analyzed by TLC to determine strychnine and roquefortine. The organic basic and neutral fractions were recombined with a late eluting GPC fraction and analyzed by GC-MS. Of 312 samples analyzed by TLC from 1995 to 2001, 35 were positive for strychnine alone, 58 were positive for both roquefortine and penitrem A, 4 were positive for roquefortine alone, and 1 was positive for bromethalin. None of the samples were positive for penitrem A alone. Samples negative by TLC were analyzed by the GC-MS extended procedure since mid-1999, and 14 have shown positive for a wide variety of compounds with convulsant activity. PMID:12580294

  17. Determination of organoarsenic warfare agents in sediment samples from Skagerrak by gas chromatography-mass spectrometry.

    PubMed

    Tørnes, John Aasulf; Opstad, Aase Mari; Johnsen, Bjørn Arne

    2006-03-01

    In 1945 the Norwegian authorities gave permission to scuttle ships loaded with captured chemical ammunition on board in an area approximately 14x4 km in size, 25 nautical miles south-east of Arendal. An investigation was carried out in 2002 to inspect four wrecks by using a remote-operated vehicle with video cameras. The Norwegian Defence Research Establishment (Forsvarets forskningsinstitutt, FFI) carried out the project on behalf of the Norwegian Pollution Control Authority (SFT). Sediment samples were collected at eight positions around each wreck. One of the wrecks was broken up into several smaller parts. Here sediments were collected at one additional position close to one of the parts. From each position, at least two sediment cores were taken up to the surface. One of the cores from each position was sliced into three parts that were immediately frozen. The other whole cores were frozen on board the ship and transported back to the laboratory in a freezer. In total, sediment samples from 33 different locations were collected and analysed for organoarsenic warfare agents and some of their decomposition products by gas chromatography-mass spectrometry (GC-MS) after derivatisation with 1-propanethiol. Most of the identified organoarsenic compounds found in the sediment samples are parts of the arsine oil mixture produced by Germany during World War II. The compounds were found both close to the wreck and at a somewhat longer distance from the wrecks. The highest concentrations were found in a sediment sample collected close to a bomb seen on the seabed. The organoarsenic warfare agents adamsite or lewisite were not found in any of the samples. Lewisite is not reported to have been produced during World War II, but was nevertheless looked for in the samples. PMID:15993928

  18. Preparative two-dimensional liquid chromatography/mass spectrometry for the purification of complex pharmaceutical samples.

    PubMed

    Zhang, Yinong; Zeng, Lu; Pham, Catherine; Xu, Rongda

    2014-01-10

    A new preparative two-dimensional liquid chromatography/mass spectrometry system (2D LC-LC/MS) has been designed and implemented to enhance capability and resolving power for the separation and purification of pharmaceutical samples. The system was constructed by modifications of a conventional preparative LC/MS instrument with the addition of a set of switching valves and a sample loop, as well as interfacing a custom software program with MassLynx. The system integrates two chromatographic separations from the first and second dimensions into a single automated run to perform the purification of a target compound from a complex mixture without intermediate steps of sample preparation. The chromatography in the first dimension, operated in the heart-cutting mode, separates the target compound from the impurities by mass-triggered fractionation based on its molecular weight. This purified fraction from the first dimension is stored in the sample loop, and then gets transferred to the second column by using at-column dilution. A control software program, coined Prep 2D LCMS, was designed to integrate with MassLynx to retrieve data acquisition status. All of the chromatographic hardware components used in this preparative 2D LC-LC/MS system are from the original open access preparative LC/MS system, which has high level of robustness and affords easy and user-friendly operation. The new system is very versatile and capable of collecting multiple fractions with different masses under various purification modes as configured in the methods, such as conventional one-dimensional (1D) purification and/or 2D purification. This new preparative 2D LC-LC/MS system is therefore the ideal tool for medicinal chemistry lab in drug discovery environment. PMID:24309715

  19. Determination of nitrogen-15 enrichment of nitrate and nitrite using thermospray liquid chromatography-mass spectrometry

    SciTech Connect

    Hogge, L.R.; Hynes, R.K.; Nelson, L.M.; Vestal, M.L.

    1986-11-01

    A new method has been developed for the determination of percent /sup 15/N enrichment in NO/sub 2//sup -/ and NO/sub 3//sup -/ that is both rapid and sensitive. NO/sub 2//sup -/ and NO/sub 3//sup -/ separation was done by use of reverse-phase liquid chromatography with a mobile phase consisting of ammonium acetate with tetrabutylammonium acetate as the ion pair reagent. The % /sup 15/N in isotopically enriched anions was determined by using thermospray liquid chromatography-mass spectrometry (LC-MS). Enrichment values were obtained on as little as 20 ng of NO/sub 2//sup -/-N/20 ..mu..L and 4 ng of NO/sub 3//sup -/-N/20 ..mu..L. The linear regression curve was plotted for the observed enrichment vs. the actual enrichment over the range from the natural abundance to 25% enrichment for each anion and the equation for the linear regression calculated (y = 1.16x + 0.7577 for NO/sub 2//sup -/ and y = 0.951x + 0.447 for NO/sub 3//sup -/). The coefficient of determination for the NO/sub 2//sup -/ and NO/sub 3//sup -/ curves was 0.988 and 0.987, respectively. The dynamic range of the method was found to be suitable for the range of NO/sub 2//sup -/ and NO/sub 3//sup -/ expected in plant xylem sap. Xylem sap samples obtained from NO/sub 3//sup -/ fed pea, Pisum sativum cv. Homesteader (3.9 ..mu..g of NO/sub 3//sup -/-N/mL, 24.7% /sup 15/N), contained a /sup 15/N enrichment of 25.4% +/- 0.7%.

  20. Nitrate Reduction in a Groundwater Microcosm Determined by 15N Gas Chromatography-Mass Spectrometry

    PubMed Central

    Bengtsson, Gran; Annadotter, Helne

    1989-01-01

    Aerobic and anaerobic groundwater continuous-flow microcosms were designed to study nitrate reduction by the indigenous bacteria in intact saturated soil cores from a sandy aquifer with a concentration of 3.8 mg of NO3?-N liter?1. Traces of 15NO3? were added to filter-sterilized groundwater by using a Darcy flux of 4 cm day?1. Both assimilatory and dissimilatory reduction rates were estimated from analyses of 15N2, 15N2O, 15NH4+, and 15N-labeled protein amino acids by capillary gas chromatography-mass spectrometry. N2 and N2O were separated on a megabore fused-silica column and quantified by electron impact-selected ion monitoring. NO3? and NH4+ were analyzed as pentafluorobenzoyl amides by multiple-ion monitoring and protein amino acids as their N-heptafluorobutyryl isobutyl ester derivatives by negative ion-chemical ionization. The numbers of bacteria and their [methyl-3H]thymidine incorporation rates were simultaneously measured. Nitrate was completely reduced in the microcosms at a rate of about 250 ng g?1 day?1. Of this nitrate, 80 to 90% was converted by aerobic denitrification to N2, whereas only 35% was denitrified in the anaerobic microcosm, where more than 50% of NO3? was reduced to NH4+. Assimilatory reduction was recorded only in the aerobic microcosm, where N appeared in alanine in the cells. The nitrate reduction rates estimated for the aquifer material were low in comparison with rates in eutrophic lakes and coastal sediments but sufficiently high to remove nitrate from an uncontaminated aquifer of the kind examined in less than 1 month. PMID:16348048

  1. Fluoroacetylation/fluoroethylesterification as a derivatization approach for gas chromatography-mass spectrometry in metabolomics: preliminary study of lymphohyperplastic diseases.

    PubMed

    Karamani, Anna A; Fiamegos, Yiannis Ch; Vartholomatos, George; Stalikas, Constantine D

    2013-08-01

    Metabolic fingerprinting in combination with gas chromatography and multivariate analysis is being extensively employed for the improved understanding of biological changes induced by endogenous or exogenous factors. Chemical derivatization increases the sensitivity and specificity of gas chromatography-mass spectrometry (GC-MS) for polar or thermally labile biological compounds, which bear derivatizable groups. Thus, there is a constant demand for simple methods of derivatization and separation that satisfy the need for metabolite analysis, identifying as many chemical classes of compounds as possible. In this study, an optimized protocol of extraction and derivatization is established as a generally applicable method for the analysis of a wide range of classes of metabolites in urine, whole blood and saliva. Compounds of biological relevance bearing hydroxyl- carboxyl- and amino-groups are derivatized using single-step fluoroacetylation/fluoroethylesterification after proper optimization of the protocol. Subsequently, the developed derivatization procedure is engaged in finding blood metabolic biomarkers, induced by lymphohyperplastic disease, through the metabolomic fingerprinting approach, the multivariate modeling (hierarchical cluster analysis) and GC-MS. Our preliminary, GC-MS-based metabolomic fingerprinting study underlines the contribution of certain metabolites to the discrimination of patients with lymphohyperplastic diseases. PMID:23806352

  2. Rapid Determination of Clenbuterol in Pork by Direct Immersion Solid-Phase Microextraction Coupled with Gas Chromatography-Mass Spectrometry.

    PubMed

    Ye, Diru; Wu, Susu; Xu, Jianqiao; Jiang, Ruifen; Zhu, Fang; Ouyang, Gangfeng

    2016-02-01

    Direct immersion solid-phase microextraction (DI-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was developed for rapid analysis of clenbuterol in pork for the first time. In this work, a low-cost homemade 44 µm polydimethylsiloxane (PDMS) SPME fiber was employed to extract clenbuterol in pork. After extraction, derivatization was performed by suspending the fiber in the headspace of the 2 mL sample vial saturated with a vapor of 100 µL hexamethyldisilazane. Lastly, the fiber was directly introduced to GC-MS for analysis. All parameters that influenced absorption (extraction time), derivatization (derivatization reagent, time and temperature) and desorption (desorption time) were optimized. Under optimized conditions, the method offered a wide linear range (10-1000 ng g(-1)) and a low detection limit (3.6 ng g(-1)). Finally, the method was successfully applied in the analysis of pork from the market, and recoveries of the method for spiked pork were 97.4-105.7%. Compared with the traditional solvent extraction method, the proposed method was much cheaper and fast. PMID:26306572

  3. Versatile characterization of glycosylation modification in CTLA4-Ig fusion proteins by liquid chromatography-mass spectrometry

    PubMed Central

    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

  4. Volatile composition of Catharanthus roseus (L.) G. Don using solid-phase microextraction and gas chromatography/mass spectrometry.

    PubMed

    De Pinho, P Guedes; Gonçalves, Rui F; Valentão, Patrícia; Pereira, David M; Seabra, Rosa M; Andrade, Paula B; Sottomayor, Mariana

    2009-04-01

    A total of 88 volatile and semi-volatile components were formally or tentatively identified in flowers, leaves and stems of Catharanthus roseus (L.) G. Don (cv. Little Bright Eye), by headspace solid-phase microextraction (HS-SPME) and by dichloromethane extraction, combined with gas chromatography-mass spectrometry (GC-MS). These include some diterpenic compounds (manool and manoyl oxides), a sesquiterpen (alpha-bisabolol), and some pyridine, pyrazine, indol and carotenoid derivatives. Applying multivariate analysis (principal component analysis and agglomerative hierarchic cluster analysis) to the HS-SPME-GC-MS data, it was possible to characterize each part of the vegetal material using a relative small number of compounds. Hence, flowers were richer in terpenic molecules (including limonene), alpha-bisabolol, methyljasmonate, cis-jasmone, 2-phenylethanol, phenylacetaldehyde, trans-2-octenal, benzylic alcohol and 2-isobutyl-3-methoxypyrazine. Leaves can be characterized by the methyl and propyl esters of fatty acids, mono- and disaturated, trans-phytol, carotenoid derivative compounds, hydrofarnesylacetone, methylanthranilate, manool and epi-manool oxide, while stems have high levels of volatile aldehydes, such as hexanal, octanal, cis-2-nonenal, cis-2-decenal, cis, trans-2,6-nonadienal, trans, trans-2,4-decadienal and cis, trans-2,4-decadienal. Dichloromethane extraction allowed also the identification of some alkaloid-like compounds that were not detected by HS-SPME. PMID:19186019

  5. Development of a sample preparation method for monitoring correct disulfide linkages of monoclonal antibodies by liquid chromatography-mass spectrometry.

    PubMed

    Wang, Yi; Li, Huijuan; Shameem, Mohammed; Xu, Wei

    2016-02-15

    The number and positions of disulfide linkages in a therapeutic monoclonal antibody (mAb) play a crucial role in forming and stabilizing a correct mAb structure that is critical to its function. Peptide mapping by liquid chromatography-mass spectrometry (LC-MS) analysis of enzymatically digested mAb under nonreducing condition is a powerful method for disulfide linkage characterization to ensure mAb drug function and quality. However, the development of a robust sample preparation method with improved digestion efficiency and minimized disulfide scrambling for disulfide linkage analysis is essential but challenging. In this study, a sample preparation method for analysis of correct disulfide linkages in therapeutic mAbs was developed. Instead of common trypsin digestion, Lys-C plus trypsin was used in this approach to improve digestion efficiency. In addition, lower digestion temperature (25C) and lower digestion pH (pH 6.8) were also examined to minimize disulfide scrambling. Our results showed that Lys-C plus trypsin digestion at pH 6.8 and 25C is a better sample preparation condition for all therapeutic mAbs tested in this study because of a better digestion efficiency (all expected disulfide linkages can be confidently observed) and minimal disulfide scrambling. PMID:26656925

  6. Identification of gibberellins A20 and A 29 in seed of Pisum sativum cv. Progress No. 9 by combined gas chromatography-mass spectrometry.

    PubMed

    Frydman, V M; Macmillan, J

    1973-03-01

    The gibberellin A1 (GA1)-like and GA5-like fractions from immature seeds of Pisum sativum cv. Progress No. 9 were identified by combined gas chromatography-mass spectrometry as GA29 and GA20 respectively. PMID:24458812

  7. EPA Method 525.3 - Determination of Semivolatile Organic Chemicals in Drinking Water by Solid Phase Extraction and Capillary Column Gas Chromatography/Mass Spectrometry (GC/MS)

    EPA Science Inventory

    Method 525.3 is an analytical method that uses solid phase extraction (SPE) and gas chromatography/mass spectrometry (GC/MS) for the identification and quantitation of 125 selected semi-volatile organic chemicals in drinking water.

  8. Headspace-trap gas chromatography-mass spectrometry for determination of sulphur mustard and related compounds in soil.

    PubMed

    Røen, Bent T; Unneberg, Erik; Tørnes, John Aa; Lundanes, Elsa

    2010-04-01

    Methods for trace determination of sulphur mustard (HD) and some related cyclic sulphur compounds in soil samples have been developed using headspace-trap in combination with gas chromatography-mass spectrometry (GC-MS). Two quite different types of soil were employed in the method optimisation (sandy loam and silty clay loam). Prior to analysis, water saturated with sodium chloride was added to the samples, at a water to soil ratio of 1:1. A detection limit of 3 ng/g was achieved for HD, while the cyclic sulphur compounds 1,4-thioxane, 1,3-dithiolane and 1,4-dithiane could be detected at 0.2-0.7 ng/g. The methods were validated in the concentration range from the limit of quantification (LOQ) to hundred times LOQ. The within assay precision at fifty times LOQ was 6.9-7.3% relative standard deviation (RSD) for determination of the cyclic sulphur compounds, and 15% RSD for determination of HD. Recoveries were in the range of 43-60% from the two soil types. As the technique requires very little sample preparation, the total time for sample handling and analysis was less than 1h. The technique was successfully employed for the determination of cyclic sulphur compounds in a sediment sample from an old dumping site for chemical munitions, known to contain HD degradation products. PMID:20189185

  9. Determination of Volatile Compounds in Four Commercial Samples of Japanese Green Algae Using Solid Phase Microextraction Gas Chromatography Mass Spectrometry

    PubMed Central

    Yoshikawa, Keisuke; Fujita, Akira; Mase, Nobuyuki; Watanabe, Naoharu

    2014-01-01

    Green algae are of great economic importance. Seaweed is consumed fresh or as seasoning in Japan. The commercial value is determined by quality, color, and flavor and is also strongly influenced by the production area. Our research, based on solid phase microextraction gas chromatography mass spectrometry (SPME-GC-MS), has revealed that volatile compounds differ intensely in the four varieties of commercial green algae. Accordingly, 41 major volatile compounds were identified. Heptadecene was the most abundant compound from Okayama (Ulva prolifera), Tokushima (Ulva prolifera), and Ehime prefecture (Ulva linza). Apocarotenoids, such as ionones, and their derivatives were prominent volatiles in algae from Okayama (Ulva prolifera) and Tokushima prefecture (Ulva prolifera). Volatile, short chained apocarotenoids are among the most potent flavor components and contribute to the flavor of fresh, processed algae, and algae-based products. Benzaldehyde was predominant in seaweed from Shizuoka prefecture (Monostroma nitidum). Multivariant statistical analysis (PCA) enabled simple discrimination of the samples based on their volatile profiles. This work shows the potential of SPME-GC-MS coupled with multivariant analysis to discriminate between samples of different geographical and botanical origins and form the basis for development of authentication methods of green algae products, including seasonings. PMID:24592162

  10. Determination of metaldehyde in human serum by headspace solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

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

    2008-11-15

    A rapid headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) method has been developed for the determination of metaldehyde in human serum samples. Metaldehyde is extensively used as a molluscicide for the control of slugs and snails, and cases of metaldehyde poisoning have been reported. Metaldehyde was headspace-extracted on a polydimethylsiloxane (PDMS) fiber at 70 degrees C for 25 min, desorbed, and analyzed rapidly by GC-MS. The method was validated for limit of detection (LOD), linearity, precision, and recovery. Although the recovery of the sample was very low, the method itself was rapid with a low detection limit of 0.25 microg/ml, R.S.D. value 12.6%, and linearity range 0.5-25.0 microg/ml (r(2)=0.999). The results demonstrated that the SPME-GC-MS method for the analysis of metaldehyde is simple, rapid, solvent-free, and does not require any pre-analysis conversions. PMID:18945651

  11. A rapid and simple procedure for the determination of ephedrine alkaloids in dietary supplements by gas chromatography-mass spectrometry.

    PubMed

    Marchei, Emilia; Pellegrini, Manuela; Pacifici, Roberta; Zuccaro, Piergiorgio; Pichini, Simona

    2006-08-28

    A simple method for the determination of ephedrine alkaloids: ephedrine (EF), pseudoephedrine (PE), norpseudoephedrine (NPE), norephedrine (NE) and methylpseudoephedrine (MPE) in dietary supplements by gas chromatography-mass spectrometry is described. After the addition of 3,4-methylenedioxypropylamphetamine as internal standard, a liquid-liquid extraction procedure in alkaline conditions with chloroform/isopropanol (9:1, v/v) was applied to the samples prior to analysis. Chromatography was performed on a fused capillary column and analytes, derivatized with pentafluoropropionic anhydride, were determined in the selected-ion-monitoring (SIM) mode. The method was validated in the range 0.3-10 microg/mg for EP, 0.06-2.5 microg/mg for PE and NPE and 0.04-1 microg/mg NE and MPE. Mean recovery ranged between 65.7 and 81.3% for the different analytes in dietary supplements. The quantification limits were 0.3 microg/mg for EP, 0.06 microg/mg for PE, 0.04 microg/mg for NPE, NE and MPE. The method was applied to analysis of various dietary supplements containing Ma-huang (Ephedra Sinica) and Sida Cordifolia plant extracts promoted for aiding weight control and boosting sports performance and energy. PMID:16580167

  12. Pilot for Validation of Online Pretreatments for Analyses of Organics by Gas Chromatography-Mass Spectrometry: Application to Space Research.

    PubMed

    David, M; Musadji, N-Y; Labanowski, J; Sternberg, R; Geffroy-Rodier, C

    2016-05-17

    The search for complex organic molecules in extraterrestrial environments, including important biomolecules such as amino and fatty acids, will require a space compatible sample handling system to enable their detection by gas chromatography-mass spectrometry (GC-MS). For the future Mars exploratory mission Exomars 2018 aimed at organic molecules detection, a dedicated laboratory pilot, called Device for Pretreatment of Sample (DPS), reproducing representative space operating conditions has been developed. After its optimization, it aimed at validating under development protocols and interpreting forthcoming in situ resulting data. The DPS, dedicated to organic compounds' analysis, is discussed in terms of its technical features. The derivatization is carried out on a 50-100 mg mineral sample in a 4 mL reactor coupled with a GC-MS injector to simulate on line in situ derivatization-volatilization-transfer steps. Three derivatization reactions have been carried out with N-methyl-N-(tert-butyldimethylsilyl)-trifluoroacetamide (MTBSTFA) as silylating reagent, N,N-dimethylformamide dimethylacetal (DMF-DMA) and tetramethylammonium hydroxide (TMAH) as methylating agents. The performances are illustrated by comparison of conventional and in situ silylation, developed for space research applications, using terrestrial mineral matrix and Mars analog materials enriched with 25 nmol of each targeted organic molecule. The work presented in this rationale has established that the use of derivatization reactions widens the scope of targeted molecules but also clearly points out mineral matrix effect. Decreasing mineral influence on pretreatment will be the next scientific challenge in in situ analysis. PMID:27108566

  13. A Gas Chromatography-Mass Spectrometry Based Study on Urine Metabolomics in Rats Chronically Poisoned with Hydrogen Sulfide

    PubMed Central

    Deng, Mingjie; Zhang, Meiling; Sun, Fa; Ma, Jianshe; Hu, Lufeng; Yang, Xuezhi; Lin, Guanyang; Wang, Xianqin

    2015-01-01

    Gas chromatography-mass spectrometry (GS-MS) in combination with multivariate statistical analysis was applied to explore the metabolic variability in urine of chronically hydrogen sulfide- (H2S-) poisoned rats relative to control ones. The changes in endogenous metabolites were studied by partial least squares-discriminate analysis (PLS-DA) and independent-samples t-test. The metabolic patterns of H2S-poisoned group are separated from the control, suggesting that the metabolic profiles of H2S-poisoned rats were markedly different from the controls. Moreover, compared to the control group, the level of alanine, d-ribose, tetradecanoic acid, L-aspartic acid, pentanedioic acid, cholesterol, acetate, and oleic acid in rat urine of the poisoning group decreased, while the level of glycine, d-mannose, arabinofuranose, and propanoic acid increased. These metabolites are related to amino acid metabolism as well as energy and lipid metabolism in vivo. Studying metabolomics using GC-MS allows for a comprehensive overview of the metabolism of the living body. This technique can be employed to decipher the mechanism of chronic H2S poisoning, thus promoting the use of metabolomics in clinical toxicology. PMID:25954748

  14. A rapid and simple procedure for the determination of synephrine in dietary supplements by gas chromatography-mass spectrometry.

    PubMed

    Marchei, Emilia; Pichini, Simona; Pacifici, Roberta; Pellegrini, Manuela; Zuccaro, Piergiorgio

    2006-06-16

    A simple and rapid procedure based on gas chromatography-mass spectrometry (GC-MS) is described for determination of synephrine, active principle of Citrus aurantium plant, in solid and liquid dietary supplements. After the addition of 3,4-methylenedioxypropylamphetamine as internal standard (I.S.), a liquid-liquid extraction procedure in alkaline conditions with chloroform/isopropanol (9:1, v/v) was applied to the samples prior to analysis. Chromatography was performed on a fused capillary column and synephrine and I.S., derivatized with pentafluoropropionic anhydride, were determined in the selected-ion-monitoring (SIM) mode. The method was validated in the range 0.1-50 microg/mg or microg/mL synephrine. Mean recovery ranged between 89.3% and 90.5% in both solid and liquid dietary supplements. The quantification limit was 0.1 microg/mg or microg/ml. The method was applied to analysis of various dietary supplements promoted for aiding weight control containing, among other constituents such as ephedrine alkaloids and methylxanthines, Citrus aurantium. Amount of synephrine present in such products ranged from 3.1 microg/mg solid product to 480.2 microg/mL liquid product. PMID:16698212

  15. Characterization of aroma compounds of Chinese famous liquors by gas chromatography-mass spectrometry and flash GC electronic-nose.

    PubMed

    Xiao, Zuobing; Yu, Dan; Niu, Yunwei; Chen, Feng; Song, Shiqing; Zhu, Jiancai; Zhu, Guangyong

    2014-01-15

    Aroma composition of five Chinese premium famous liquors with different origins and liquor flavor types was characterized by gas chromatography-mass spectrometry (GC-MS) and flash gas chromatographic electronic nose system. Eighty-six aroma compounds were identified, including 5 acids, 34 esters, 10 alcohols, 9 aldehydes, 4 ketones, 4 phenols, and 10 nitrous and sulfuric compounds. To investigate possible correlation between aroma compounds identified by GC-MS and sensory attributes, multivariate ANOVA-PLSR (APLSR) was performed. It turned out that there were 30 volatile composition, ethyl acetate, ethyl propanoate, ethyl 2-methyl butanoate, ethyl 3-methyl butanoate, ethyl lactate, ethyl benzenacetate, 3-methylbutyl acetate, hexyl acetate, 3-methyl-1-butanol, 1-heptanol, phenylethyl alcohol, acetaldehyde, 1,1-diethoxy-3-methyl butane, furfural, benzaldehyde, 5-methyl-2-furanal, 2-octanone, 2-n-butyl furan, dimethyl trisulfied and 2,6-dimethyl pyrazine, ethyl nonanoate, isopentyl hexanoate, octanoic acid, ethyl 5-methyl hexanoate, 2-phenylethyl acetate,ethyl oleate, propyl hexanoate, butanoic acid and phenol, ethyl benzenepropanoate, which showed good coordination with Chinese liquor characteristics. The multivariate structure of this electronic nose responses was then processed by principal component analysis (PCA) and hierarchical cluster analysis (HCA). According to the obtained results, GC-MS and electronic nose can be used for the differentiation of the liquor origins and flavor types. PMID:24333641

  16. [Determination of migration of 25 primary aromatic amines from food contact plastic materials by gas chromatography-mass spectrometry].

    PubMed

    Li, Ying; Li, Chengfa; Xiao, Daoqing; Liang, Feng; Chen, Zhinan; Schen, Xuhui; Sun, Xiaoying; Li, Yongtao

    2013-01-01

    A solid phase extraction (SPE) combination with gas chromatography-mass spectrometry (GC-MS) was developed for the determination of the migration of 25 primary aromatic amines (PAAs) from food contact plastic materials and articles. The samples were extracted by deionized water and 30 g/L acetic acid, and the pH value of the solution was adjusted to 8 - 10 with ammonia. The extracts were cleaned up and concentrated on an SPE column, then eluted by equal volume of methyl-tert-butyl ether and ethanol. The analysis of the target compounds was performed by GC-MS. The results indicated that the limits of detection were in the range of 0.4 -2.0 microg/kg for different PAAs. The recoveries and relative standard deviations (n = 7) of 10 microg/kg PAAs ranged from 51.6% -118.4% and 0.5% -9.8%, respectively, except the 2,4-diaminoanisole in the acid simulant. The effects of different experimental conditions such as the pH value and volume ratio of methyl-tert-butyl ether and ethanol were studied. The results showed that the method is accurate and stable, and could meet the requirement of the European Commission Regulation (EU) No 10/2011 for the determination of primary aromatic amines. It can be applied in the analysis of the primary aromatic amines in real food contact plastic material and article samples. PMID:23667989

  17. 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

  18. Gas Chromatography- Mass Spectrometry Based Metabolomic Approach for Optimization and Toxicity Evaluation of Earthworm Sub-Lethal Responses to Carbofuran

    PubMed Central

    Saxena, Prem Narain

    2013-01-01

    Despite recent advances in understanding mechanism of toxicity, the development of biomarkers (biochemicals that vary significantly with exposure to chemicals) for pesticides and environmental contaminants exposure is still a challenging task. Carbofuran is one of the most commonly used pesticides in agriculture and said to be most toxic carbamate pesticide. It is necessary to identify the biochemicals that can vary significantly after carbofuran exposure on earthworms which will help to assess the soil ecotoxicity. Initially, we have optimized the extraction conditions which are suitable for high-throughput gas chromatography mass spectrometry (GC-MS) based metabolomics for the tissue of earthworm, Metaphire posthuma. Upon evaluation of five different extraction solvent systems, 80% methanol was found to have good extraction efficiency based on the yields of metabolites, multivariate analysis, total number of peaks and reproducibility of metabolites. Later the toxicity evaluation was performed to characterize the tissue specific metabolomic perturbation of earthworm, Metaphire posthuma after exposure to carbofuran at three different concentration levels (0.15, 0.3 and 0.6 mg/kg of soil). Seventeen metabolites, contributing to the best classification performance of highest dose dependent carbofuran exposed earthworms from healthy controls were identified. This study suggests that GC-MS based metabolomic approach was precise and sensitive to measure the earthworm responses to carbofuran exposure in soil, and can be used as a promising tool for environmental eco-toxicological studies. PMID:24324663

  19. New pilot for validation of automated analyses of organics by gas chromatography mass spectrometry (GCMS): application to space researches

    NASA Astrophysics Data System (ADS)

    Sternberg, Robert; Buch, Arnaud; Chazalnoel, Pascale; Geffroy, Claude; David, Marc

    The search for complex organic molecules in extraterrestrial environments, including important biomolecules such as amino acids and carboxylic acids, will require after an extraction a derivatization step to transform these organic compounds into species that are sufficiently volatile to be detected by gas chromatography mass spectrometry (GCMS). Current and future space missions, such as Mars Science Laboratory (MSL 2011, will include such derivatization method and thus a dedicated laboratory pilot is needed to validate protocols before launch of the probes. A new in situ generic Derivatization-Pyrolysis Unit (DPU) is presented. Derivatization is carried out in a 4 mL reactor placed on a GCMS injector for automated derivatization as well as for pre- and post treatment of the sample. The DPU unit is evaluated in terms of its technical features. The performances are illustrated with applications including conventional and in situ derivatization for using terrestrial Mars analog materials enriched by a 5 nmol amino acids solution. The DPU allows the analysis of a wide range of molecules to be detected and can be adapted to samples from any solid spatial object such as Mars, asteroids and comets. This pilot is a good basis for the validation of future generations of instruments, such as the Mars Organic Molecule Analyzer (MOMA) of the Exomars 2018 mission, dedicated to the search for organics in spatial environments.

  20. Determination of organoarsenicals in the environment by solid-phase microextraction-gas chromatography-mass spectrometry.

    SciTech Connect

    Szostek, B.; Aldstadt, J. H.; Environmental Research

    1998-05-22

    The development of a method for the analysis of organoarsenic compounds that combines dithiol derivatization with solid-phase microextraction (SPME) sample preparation and gas chromatography-mass spectrometry (GC-MS) is described. Optimization focused on a SPME-GC-MS procedure for determination of 2-chlorovinylarsonous acid (CVAA), the primary decomposition product of the chemical warfare agent known as Lewisite. Two other organoarsenic compounds of environmental interest, dimethylarsinic acid and phenylarsonic acid, were also studied. A series of dithiol compounds was examined for derivatization of the arsenicals, and the best results were obtained either with 1,3-propanedithiol or 1,2-ethanedithiol. The derivatization procedure, fiber type, and extraction time were optimized. For CVAA, calibration curves were linear over three orders of magnitude and limits-of-detection were <6x10{sup -9} M in solution, the latter a more than 400x improvement compared to conventional solvent extraction GC-MS methods. A precision of <10% R.S.D. was typical for the SPME-GC-MS procedure. The method was applied to a series of water samples and soil/sediment extracts, as well as to aged soil samples that had been contaminated with Lewisite.

  1. Unknown exposures: gaps in basic characterization addressed with person-portable gas chromatography-mass spectrometry instrumentation.

    PubMed

    Smith, Philip A; Roe, Marc T A; Sadowski, Charles; Lee, Edgar D

    2011-03-01

    A newly developed person-portable gas chromatography-mass spectrometry (GC-MS) system was used to analyze several solvent standards, contact cement, paint thinner, and polychlorinated biphenyl samples. Passive solid phase microextraction sampling and fast chromatography with a resistively heated low thermal mass GC column were used. Results (combined sampling and analysis) were obtained in <2 min for solvent, contact cement, and paint thinner samples, and in <13 min for the polychlorinated biphenyl sample. Mass spectra produced by the small toroidal ion trap detector used were similar to those produced with heavily used transmission quadrupole mass spectrometers for polychlorinated biphenyl compounds, simple alkanes, and cycloalknes, while mass spectra for benzene and the ketone compounds analyzed showed evidence for ion/molecule reactions in the ion trap. For one of the contact cement samples analyzed, no evidence was found to indicate the presence of n-hexane, although the relevant material safety data sheet listed this ingredient. Specific chemical constituents corresponding to a potentially wide range of petroleum distillate compounds were identifiable from GC-MS analyses. The possibility for an improved basic characterization step in the exposure assessment process exists with the availability of fast, person-portable GC-MS, although work is needed to further refine this tool and understand the best ways it may be used. PMID:21318921

  2. Accuracy profile validation of a new analytical method for propane measurement using headspace-gas chromatography-mass spectrometry.

    PubMed

    Smith, Fiona; Augsburger, Marc; Varlet, Vincent

    2014-03-01

    Propane can be responsible for several types of lethal intoxication and explosions. Quantifying it would be very helpful to determine in some cases the cause of death. Some gas chromatography-mass spectrometry (GC-MS) methods of propane measurements do already exist. The main drawback of these GC-MS methods described in the literature is the absence of a specific propane internal standard necessary for accurate quantitative analysis. The main outcome of the following study was to provide an innovative Headspace-GC-MS method (HS-GC-MS) applicable to the routine determination of propane concentration in forensic toxicology laboratories. To date, no stable isotope of propane is commercially available. The development of an in situ generation of standards is thus presented. An internal-labeled standard gas (C₃DH₇) is generated in situ by the stoichiometric formation of propane by the reaction of deuterated water (D₂O) with Grignard reagent propylmagnesium chloride (C₃H₇MgCl). The method aims to use this internal standard to quantify propane concentrations and, therefore, to obtain precise measurements. Consequently, a complete validation with an accuracy profile according to two different guidelines, the French Society of Pharmaceutical Sciences and Techniques (SFSTP) and the Gesellschaft für toxikologische und Forensische Chemie (GTFCh), is presented. PMID:24327620

  3. Determining the levels of volatile organic pollutants in urban air using a gas chromatography-mass spectrometry method.

    PubMed

    Nicoara, Simona; Tonidandel, Loris; Traldi, Pietro; Watson, Jonathan; Morgan, Geraint; Popa, Ovidiu

    2009-01-01

    The paper presents the application of a method based on coupled gas chromatography-mass spectrometry, using an isotopically labelled internal standard for the quantitative analysis of benzene (B), toluene (T), ethyl benzene (E), and o-, m-, p-xylenes (X). Their atmospheric concentrations were determined based on short-term sampling, in different sites of Cluj-Napoca, a highly populated urban centre in N-W Romania, with numerous and diversified road vehicles with internal combustion engines. The method is relatively inexpensive and simple and shows good precision and linearity in the ranges of 7-60 mug/m(3) (B), 13-90 mug/m(3) (T), 7-50 mug/m(3) (E), 10-70 mug/m(3) (X-m,p), and 20-130 mug/m(3) (X-o). The limits of quantitation/detection of the method LOQ/LOD are of 10/5 mug/m(3) (Xo), 5/3 mug/m(3) (B, E, X-m,p), and of 3/1 mug/m(3) (T), respectively. PMID:20168976

  4. Mass spectral studies on vinylic degradation products of sulfur mustards under gas chromatography/mass spectrometry conditions.

    PubMed

    Sai Sachin, L; Karthikraj, R; Kalyan Kumar, K; Sony, T; Prasada Raju, N; Prabhakar, S

    2015-01-01

    Sulfur mustards are a class of vesicant chemical warfare agents that rapidly degrade in environmental samples. The most feasible degradation products of sulfur mustards are chloroethyl vinylic compounds and divinylic compounds, which are formed by the elimination of one and two HCl molecules from sulfur mustards, respectively. The detection and characterization of these degradation products in environmental samples are an important proof for the verification of sulfur mustard usage. In this study, we synthesized a set of sulfur mustard degradation products, i.e., divinylic compounds (1-7) and chloroethyl vinylic compounds (8-14), and characterized using gas chromatography/mass spectrometry (GC/MS) under electron ionization (EI) and chemical ionization (CI) (methane) conditions. The EI mass spectra of the studied compounds mainly included the fragment ions that resulted from homolytic cleavages with or without hydrogen migrations. The divinylic compounds (1-7) showed [M-SH](+) ions, whereas the chloroethylvinyl compounds (8-14) showed [M-Cl](+) and [M-CH2CH2Cl](+) ions. Methane/CI mass spectra showed [M+H](+) ions and provided molecular weight information. The GC retention index (RI) values were also calculated for the studied compounds. The EI and CI mass spectral data together with RI values are extremely useful for off-site analysis for the verification of the chemical weapons convention and also to participate in official Organization for the Prohibition of Chemical Weapons proficiency tests. PMID:26764309

  5. Direct detection of Mycobacterium tuberculosis in sputum: A validation study using solid phase extraction-gas chromatography-mass spectrometry.

    PubMed

    Mourão, Marta P B; Kuijper, Sjoukje; Dang, Ngoc A; Walters, Elisabetta; Janssen, Hans-Gerd; Kolk, Arend H J

    2016-02-15

    Tuberculosis (TB) remains a worldwide health problem, especially in developing countries. Correct identification of Mycobacterium tuberculosis (MTB) infection is extremely important for providing appropriate treatment and care to patients. Here we describe a solid phase extraction-gas chromatography-mass spectrometry method (SPE-THM-GC-MS) for the detection of five biomarkers for M. tuberculosis. The method for classification is developed and validated through the analysis of 112 sputum samples from patients suspected of having TB. Twenty of twenty-five MTB culture-positive sputum samples were correctly classified as positive by our improved SPE-THM-GC-MS method. Eighty-five of eighty-seven MTB culture-negative samples were also negative by SPE-THM-GC-MS. The overall sensitivity of the new SPE-THM-GC-MS method is 80% (20/25) and the specificity is 98% (85/87) compared with culture. The method proved to be reliable and, although complex in principle, easy to operate due to the high degree of automation. PMID:26807702

  6. [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

  7. [Determination of musk ketone in aquatic products by gas chromatography-mass spectrometry with dispersive solid phase extraction].

    PubMed

    Ding, Liping; Guo, Jing; Chen, Zhitao; Zhao, Jianhui; Zheng, Ling; Cai, Wei

    2013-05-01

    A dispersive solid phase extraction coupled with gas chromatography-mass spectrometry (GC-MS) method was established for the determination of trace amounts of musk ketone in aquatic products. The target analyte in the samples was extracted with acetonitrile containing 1% acetic acid, cleaned-up with the mixture of N-propyl-ethylenediamine (PSA), C18 and graphitized carbon (GCB), and analyzed by GC-MS under selected ion monitoring (SIM) mode and quantified by the external standard method. The orthogonal experiment was carried out to optimize the pre-treatment conditions. Under the optimal conditions, good linear relationship was obtained in the range of 1 - 50 microg/L for musk ketone with correlation coefficient not less than 0.999, and the limits of detection (S/N = 3) was 0.30 microg/kg. The recoveries of musk ketone in the prawn and tilapia blank samples at three spiked levels of 1.0, 2.0 and 10.0 microg/kg ranged from 91.8% to 110.6% with RSDs in the range of 2.6% - 8.4%. The method is simple, rapid and accurate, and can be used for the routine analysis of musk ketone in aquatic products. PMID:24010352

  8. Rapid determination of polysaccharides in BianTi Soft Extract by spectrophotometry coupled with gas chromatography-mass spectrometry.

    PubMed

    Zheng, Minxia; Shen, Jie; Yang, Kai; Qian, Songxiang; Feng, Sujuan

    2010-04-01

    A simple approach for the rapid determination of polysaccharides in BianTi Soft Extract using spectrophotometry coupled with gas chromatography-mass spectrometry (GC-MS) was developed. The mixed standard solution composed of D-glucose, D-mannose, galactose and D-xylose in different proportions (1.00: 1.01: 0.12: 0.05) was prepared according to the monosaccharide composition analysis of the polysaccharides by GC-MS. The determination of polysaccharides by UV-Vis spectrophotometer was performed after 35-min color reaction, in which 1 ml 5% phenol and 4 ml sulfate was used. The assay of the method validation has shown that the method was stable, reliable and feasible. Furthermore, the proposed method was successfully applied in the preparation procedure of BianTi Soft Extract, selecting out optimal decoction conditions and suitable decoction container. It suggests that the convenient method could be useful for the quality control of BianTi Soft Extract. Meanwhile, it may be an alternative for polysaccharides determination of other formulations. PMID:20668575

  9. Detection and identification of carprofen and its in vivo metabolites in greyhound urine by capillary gas chromatography-mass spectrometry.

    PubMed

    Dumasia, M C; Ginn, A; Hyde, W; Peterson, J; Houghton, E

    2003-05-25

    Rimadyl (carprofen) was administered orally to the racing greyhound at a dose of 2.2 mg kg(-1). Following both alkaline and enzymatic hydrolysis, postadministration urine samples were extracted by mixed mode solid-phase extraction (SPE) cartridges to identify target analyte(s) for forensic screening and confirmatory analysis methods. The acidic isolates were derivatised as trimethylsilyl ethers (TMS) and analysed by gas chromatography-mass spectrometry (GC-MS). Carprofen and five phase I metabolites were identified. Positive ion electron ionisation (EI(+)) mass spectra of the TMS derivatives of carprofen and its metabolites show a diagnostic base peak at M(+)*. -117 corresponding to the loss of COO-Si-(CH(3))(3) group as a radical. GC-MS with positive ion ammonia chemical ionisation (CI(+)) of the compounds provided both derivatised molecular mass and some structural information. Deutromethylation-TMS derivatisation was used to distinguish between aromatic and aliphatic oxidations of carprofen. The drug is rapidly absorbed, extensively metabolised and excreted as phase II conjugates in urine. Carprofen, three aromatic hydroxy and a minor N-hydroxy metabolite were detected for up to 48 h. For samples collected between 2 and 8 h after administration, the concentration of total carprofen ranged between 200 and 490 ng ml(-1). The major metabolite, alpha-hydroxycarprofen was detected for over 72 h and therefore can also be used as a marker for the forensic screening of carprofen in greyhound urine. PMID:12705970

  10. [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

  11. Flow modulation comprehensive two-dimensional gas chromatography-mass spectrometry using ≈4mLmin(-1) gas flows.

    PubMed

    Franchina, Flavio A; Maimone, Mariarosa; Tranchida, Peter Q; Mondello, Luigi

    2016-04-01

    The main objective of the herein described research was focused on performing satisfactory flow modulation (FM), in comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC-MS), using an MS-compatible second-dimension gas flow of approx. 4mLmin(-1). The FM model used was based on that initially proposed by Seeley et al. [3]. The use of limited gas flows was enabled through fine tuning of the FM parameters, in particular the duration of the re-injection (or flushing) process. Specifically, the application of a long re-injection period (i.e., 700ms) enabled efficient accumulation-loop flushing with gas flows of about 4mLmin(-1). It was possible to apply such extended re-injection periods by using different restrictor lengths in the connections linking the modulator to the auxiliary pressure source. FM GC×GC-MS applications were performed on a mixture containing C9-10 alkanes, and on a sample of essential oil. GC×GC-MS sensitivity was compared with that attained by using conventional GC-MS analysis, in essential oil applications. It was observed that signal intensities were, in general, considerably higher in the FM GC×GC-MS experiments. PMID:26968229

  12. Comparison of gas chromatography/mass spectrometry and immunoassay techniques on concentrations of atrazine in storm runoff

    USGS Publications Warehouse

    Lydy, M.J.; Carter, D.S.; Crawford, C.G.

    1996-01-01

    Gas chromatography/mass spectrometry (GC/MS) and enzyme linked immunosorbent assay (ELISA) techniques were used to measure concentrations of dissolved atrazine in 149 surface-water samples. Samples were collected during May 1992-September 1993 near the mouth of the White River (Indiana) and in two small tributaries of the river. GC/MS was performed on a Hewlett- Packard 5971A with electron impact ionization and selected ion monitoring of filtered water samples extracted by C-18 solid phase extraction: ELISA was performed with a magnetic-particle-based assay with photometric analysis. ELISA results compared reasonably well to GC/MS measurements at concentrations below the Maximum Contaminant Level for drinking water set by the U.S. Environmental Protection Agency (3.0 ??g/L), but a systematic negative bias was observed at higher concentrations. When higher concentration samples were diluted into the linear range of calibration, the relation improved. A slight positive bias was seen in all of the ELISA data compared to the GC/MS results, and the bias could be partially explained by correcting the ELISA data for cross reactivity with other triazine herbicides. The highest concentrations of atrazine were found during the first major runoff event after the atrazine was applied. Concentrations decreased throughout the rest of the sampling period even though large runoff events occurred during this time, indicating that most atrazine loading to surface waters in the study area occurs within a few weeks after application.

  13. Comprehensive combinatory standard correction: a calibration method for handling instrumental drifts of gas chromatography-mass spectrometry systems.

    PubMed

    Deport, Coralie; Ratel, Jérémy; Berdagué, Jean-Louis; Engel, Erwan

    2006-05-26

    The current work describes a new method, the comprehensive combinatory standard correction (CCSC), for the correction of instrumental signal drifts in GC-MS systems. The method consists in analyzing together with the products of interest a mixture of n selected internal standards, and in normalizing the peak area of each analyte by the sum of standard areas and then, select among the summation operator sigma(p = 1)(n)C(n)p possible sums, the sum that enables the best product discrimination. The CCSC method was compared with classical techniques of data pre-processing like internal normalization (IN) or single standard correction (SSC) on their ability to correct raw data from the main drifts occurring in a dynamic headspace-gas chromatography-mass spectrometry system. Three edible oils with closely similar compositions in volatile compounds were analysed using a device which performance was modulated by using new or used dynamic headspace traps and GC-columns, and by modifying the tuning of the mass spectrometer. According to one-way ANOVA, the CCSC method increased the number of analytes discriminating the products (31 after CCSC versus 25 with raw data or after IN and 26 after SSC). Moreover, CCSC enabled a satisfactory discrimination of the products irrespective of the drifts. In a factorial discriminant analysis, 100% of the samples (n = 121) were well-classified after CCSC versus 45% for raw data, 90 and 93%, respectively after IN and SSC. PMID:16631179

  14. Effect of piperine on pharmacokinetics of sodium valproate in plasma samples of rats using gas chromatography-mass spectrometry method

    PubMed Central

    Parveen, Bushra; Pillai, K. K.; Tamboli, E. T.; Ahmad, Sayeed

    2015-01-01

    Piperine (PIP) is used as anticonvulsant in traditional Chinese medicine. Co-administration of low-dose sodium valproate with PIP has been regarded to have potential anticonvulsant activity. Aim: This study was intended to investigate the effect of PIP on the pharmacokinetics of sodium valproate (SVP) in the plasma samples of rats using gas chromatography-mass spectrometry (GC-MS) method. Materials and Methods: The plasma samples obtained after oral administration of SVP, 150 mg/kg and SVP, 150 mg/kg + PIP, and 5 mg/kg to male Wistar rats were used to quantify the concentrations in plasma using GC-MS method. Results: A simple and accurate method developed in-house was applied for the analysis of plasma samples of Wistar rats after oral administration of SVP and PIP + sodium valproate, respectively. The pharmacokinetic parameters reported 14.8-fold increase in plasma concentration (maximum observed concentration in the concentration-time profile), 4.6-fold increase in area under the curve and slightly prolonged time to reach that concentration (1 h) of SVP in presence of PIP. Conclusion: The study reaffirms the bioenhancing effect of PIP suggesting possibility of dose reduction of SVP while co-adminstering with PIP. PMID:26681892

  15. Coupling liquid chromatography/mass spectrometry detection with microfluidic droplet array for label-free enzyme inhibition assay.

    PubMed

    Wang, Xiu-Li; Zhu, Ying; Fang, Qun

    2014-01-01

    In this work, the combination of droplet-based microfluidics with liquid chromatography/mass spectrometry (LC/MS) was achieved, for providing a fast separation and high-information-content detection method for the analysis of nanoliter-scale droplets with complex compositions. A novel interface method was developed using an oil-covered droplet array chip to couple with an LC/MS system via a capillary sampling probe and a 4 nL injection valve without the need of a droplet extraction device. The present system can perform multistep operations including parallel enzyme inhibition reactions in nanoliter droplets, 4 nL sample injection, fast separation with capillary LC, and label-free detection with ESI-MS, and has significant flexibility in the accurate addressing and sampling of droplets of interest on demand. The system performance was evaluated using angiotensin I and angiotensin II as model samples, and the repeatabilities of peak area for angiotensin I and angiotensin II were 2.7% and 7.5% (RSD, n = 4), respectively. The present system was further applied to the screening for inhibitors of cytochrome P450 (CYP1A2) and measurement of the IC50 value of the inhibitor. The sample consumption for each droplet assay was 100 nL, which is reduced 10-100 times compared with conventional 384-multi-well plate systems usually used in high-throughput drug screening. PMID:24196165

  16. Measurement of volatile plant compounds in field ambient air by thermal desorption-gas chromatography-mass spectrometry.

    PubMed

    Cai, Xiao-Ming; Xu, Xiu-Xiu; Bian, Lei; Luo, Zong-Xiu; Chen, Zong-Mao

    2015-12-01

    Determination of volatile plant compounds in field ambient air is important to understand chemical communication between plants and insects and will aid the development of semiochemicals from plants for pest control. In this study, a thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) method was developed to measure ultra-trace levels of volatile plant compounds in field ambient air. The desorption parameters of TD, including sorbent tube material, tube desorption temperature, desorption time, and cold trap temperature, were selected and optimized. In GC-MS analysis, the selected ion monitoring mode was used for enhanced sensitivity and selectivity. This method was sufficiently sensitive to detect part-per-trillion levels of volatile plant compounds in field ambient air. Laboratory and field evaluation revealed that the method presented high precision and accuracy. Field studies indicated that the background odor of tea plantations contained some common volatile plant compounds, such as (Z)-3-hexenol, methyl salicylate, and (E)-ocimene, at concentrations ranging from 1 to 3400 ng m(-3). In addition, the background odor in summer was more abundant in quality and quantity than in autumn. Relative to previous methods, the TD-GC-MS method is more sensitive, permitting accurate qualitative and quantitative measurements of volatile plant compounds in field ambient air. PMID:26493981

  17. 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

  18. Screening and determination of benzodiazepines in whole blood using solid-phase extraction and gas chromatography/mass spectrometry.

    PubMed

    Inoue, H; Maeno, Y; Iwasa, M; Matoba, R; Nagao, M

    2000-09-11

    Benzodiazepines are one of the most widely prescribed drugs for the treatment of a wide spectrum of clinical disorders. They are used as anticonvulsants, anxiolytics, hypnotics or muscle relaxants with different duration of action. In this paper, a simple and sensitive method for the determination of benzodiazepines in whole blood using solid-phase extraction and gas chromatography/mass spectrometry (GC/MS) is described. The drugs spiked in whole blood were extracted with an Oasis HLB solid-phase extraction cartridge (Waters), which contains a copolymer designed to have a hydrophilic-lipophilic balance. GC/MS analysis was performed using a Shimadzu QP-5000 equipped with a BPX5 capillary column (15 mx0.32 mm I.D., film thickness 0.25 microm, SGE). Nineteen benzodiazepines and two thienodiazepines were well separated from each other on their SIM chromatograms and also on the TIC with the exception of oxazolam to cloxazolam separation. The blank extract from whole blood gave no peaks that interfered with all benzodiazepines and thienodiazepines on the chromatogram. The calibration curves for selected benzodiazepines with fludiazepam as an internal standard showed excellent linearity over the concentration range 5-500 ng/ml blood with a correlation coefficients of >0.995. The detection limits ranged from 0.2 to 20 ng/ml blood. The method is simple and sensitive for the determination of benzodiazepines in whole blood and seems to be useful in the practice of forensic science. PMID:10978650

  19. Determination of carbon number distributions of complex phthalates by gas chromatography-mass spectrometry with ammonia chemical ionization.

    PubMed

    Di Sanzo, Frank P; Lim, Peniel J; Han, Wenning W

    2015-01-01

    An assay method for phthalate esters with a complex mixture of isomer of varying carbon numbers, such as di-isononyl phthalate (DINP) and di-isodecyl phthalate (DIDP), using gas chromatography-mass spectrometry (GC-MS) positive chemical ionization (PCI) with 5% ammonia in methane is described. GC-MS-PCI-NH3, unlike GC-MS electron ionization (EI) (GC-MS-EI) that produces generally m/z 149 ion as the main base peak and low intensity M(+) peaks, produces higher intensity (M + 1) ions that allow the determination of total (R + R') carbon number distributions based on the various R and R' alkyl groups of the di-esters moiety. The technique allows distinguishing among the various commercial DINP and DIDP plasticizers. The carbon number distributions are determined in the acceptable range of <0.1 mole percent to >85 mole percent (m/m). Several examples of analysis made on commercial DINP and DIDP are presented. The use of only 5% instead of 100% ammonia simplifies use of GC-MS-PCI-NH3 but still produces sufficient M + 1 ion intensities that are appropriate for the assay. In addition, use of low concentrations of ammonia mitigates potential safety aspects related to use of ammonia and provides less corrosion for the instrument hardware. PMID:26240191

  20. [Determination of nine triazole pesticides in environmental waters using solid phase extraction and gas chromatography-mass spectrometry].

    PubMed

    You, Minghua; Sun, Guangda; Chen, Meng; Yuan, Dongxing

    2008-11-01

    A method was developed for the simultaneous determination of 9 triazole pesticides in environmental water using C18 cartridge for the extraction and enrichment, NH2 cartridge for the clean-up and gas chromatography-mass spectrometry for the detection. The linear range of calibration curves for the 9 target pesticides was between 0.025 mg/L and 0.500 mg/L. The detection limits were in the range of 0.002 - 0.009 microg/L. The 9 target pesticides were measured in river water and sea water at 0.025 microg/L and 0.100 microg/L spiking levels, recoveries and relative standard deviations (RSD, n = 3) were 68.4% - 113.9% and 1.6% - 6.9% for river water and 70.3% - 115.2% and 0.8% - 8.2% for sea water, respectively. The method is simple, sensitive, selective and suitable for the qualification of pesticide multiresidue analysis. It has been successfully applied to the survey of 9 triazole pesticide residues in Jiulong River Estuary, Fujian. PMID:19253548

  1. Metabolic Toxicity Screening Using Electrochemiluminescence Arrays Coupled with Enzyme-DNA Biocolloid Reactors and Liquid Chromatography-Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Hvastkovs, Eli, G.; Schenkman, John B.; Rusling, James, F.

    2012-07-01

    New chemicals or drugs must be guaranteed safe before they can be marketed. Despite widespread use of bioassay panels for toxicity prediction, products that are toxic to a subset of the population often are not identified until clinical trials. This article reviews new array methodologies based on enzyme/DNA films that form and identify DNA-reactive metabolites that are indicators of potentially genotoxic species. This molecularly based methodology is designed in a rapid screening array that utilizes electrochemiluminescence (ECL) to detect metabolite-DNA reactions, as well as biocolloid reactors that provide the DNA adducts and metabolites for liquid chromatography-mass spectrometry (LC-MS) analysis. ECL arrays provide rapid toxicity screening, and the biocolloid reactor LC-MS approach provides a valuable follow-up on structure, identification, and formation rates of DNA adducts for toxicity hits from the ECL array screening. Specific examples using this strategy are discussed. Integration of high-throughput versions of these toxicity-screening methods with existing drug toxicity bioassays should allow for better human toxicity prediction as well as more informed decision making regarding new chemical and drug candidates.

  2. Characterisation and discrimination of various types of lac resin using gas chromatography mass spectrometry techniques with quaternary ammonium reagents.

    PubMed

    Sutherland, K; del Ro, J C

    2014-04-18

    A variety of lac resin samples obtained from artists' suppliers, industrial manufacturers, and museum collections were analysed using gas chromatography mass spectrometry (GCMS) and reactive pyrolysis GCMS with quaternary ammonium reagents. These techniques allowed a detailed chemical characterisation of microgram-sized samples, based on the detection and identification of derivatives of the hydroxy aliphatic and cyclic (sesquiterpene) acids that compose the resin. Differences in composition could be related to the nature of the resin, e.g. wax-containing (unrefined), bleached, or aged samples. Furthermore, differences in the relative abundances of aliphatic hydroxyacids appear to be associated with the biological source of the resin. The diagnostic value of newly characterised lac components, including 8-hydroxyacids, is discussed here for the first time. Identification of derivatised components was aided by AMDIS deconvolution software, and discrimination of samples was enhanced by statistical evaluation of data using principal component analysis. The robustness of the analyses, together with the minimal sample size required, make these very powerful approaches for the characterisation of lac resin in museum objects. The value of such analyses for enhancing the understanding of museum collections is illustrated by two case studies of objects in the collection of the Philadelphia Museum of Art: a restorer's varnish on a painting by Luca Signorelli, and a pictorial inlay in an early nineteenth-century High Chest by George Dyer. PMID:24642395

  3. Validation of biomarkers for distinguishing Mycobacterium tuberculosis from non-tuberculous mycobacteria using gas chromatography-mass spectrometry and chemometrics.

    PubMed

    Dang, Ngoc A; Kuijper, Sjoukje; Walters, Elisabetta; Claassens, Mareli; van Soolingen, Dick; Vivo-Truyols, Gabriel; Janssen, Hans-Gerd; Kolk, Arend H J

    2013-01-01

    Tuberculosis (TB) remains a major international health problem. Rapid differentiation of Mycobacterium tuberculosis complex (MTB) from non-tuberculous mycobacteria (NTM) is critical for decisions regarding patient management and choice of therapeutic regimen. Recently we developed a 20-compound model to distinguish between MTB and NTM. It is based on thermally assisted hydrolysis and methylation gas chromatography-mass spectrometry and partial least square discriminant analysis. Here we report the validation of this model with two independent sample sets, one consisting of 39 MTB and 17 NTM isolates from the Netherlands, the other comprising 103 isolates (91 MTB and 12 NTM) from Stellenbosch, Cape Town, South Africa. All the MTB strains in the 56 Dutch samples were correctly identified and the model had a sensitivity of 100% and a specificity of 94%. For the South African samples the model had a sensitivity of 88% and specificity of 100%. Based on our model, we have developed a new decision-tree that allows the differentiation of MTB from NTM with 100% accuracy. Encouraged by these findings we will proceed with the development of a simple, rapid, affordable, high-throughput test to identify MTB directly in sputum. PMID:24146846

  4. Determination of polycyclic aromatic hydrocarbons in fresh milk by hollow fiber liquid-phase microextraction-gas chromatography mass spectrometry.

    PubMed

    Sanagi, Mohd Marsin; Loh, Saw Hong; Wan Ibrahim, Wan Aini; Hasan, Mohamed Noor; Aboul Enein, Hassan Y

    2013-02-01

    In this work, a two-phase hollow fiber liquid-phase microextraction (HF-LPME) method combined with gas chromatography-mass spectrometry (GC-MS) is developed to provide a rapid, selective and sensitive analytical method to determine polycyclic aromatic hydrocarbons (PAHs) in fresh milk. The standard addition method is used to construct calibration curves and to determine the residue levels for the target analytes, fluorene, phenanthrene, fluoranthene, pyrene and benzo[a]pyrene, thus eliminating sample pre-treatment steps such as pH adjustment. The HF-LPME method shows dynamic linearity from 5 to 500 µg/L for all target analytes with R(2) ranging from 0.9978 to 0.9999. Under optimized conditions, the established detection limits range from 0.07 to 1.4 µg/L based on a signal-to-noise ratio of 3:1. Average relative recoveries for the determination of PAHs studied at 100 µg/L spiking levels are in the range of 85 to 110%. The relative recoveries are slightly higher than those obtained by conventional solvent extraction, which requires saponification steps for fluorene and phenanthrene, which are more volatile and heat sensitive. The HF-LPME method proves to be simple and rapid, and requires minimal amounts of organic solvent that supports green analysis. PMID:22776739

  5. 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

  6. Wavelet- and Fourier-transform-based spectrum similarity approaches to compound identification in gas chromatography/mass spectrometry.

    PubMed

    Koo, Imhoi; Zhang, Xiang; Kim, Seongho

    2011-07-15

    The high-throughput gas chromatography/mass spectrometry (GC/MS) technology offers a powerful means of analyzing a large number of chemical and biological samples. One of the important analyses of GC/MS data is compound identification. In this work, novel spectral similarity measures based on the discrete wavelet and Fourier transforms were proposed. The proposed methods are composite similarities that are composed of weighted intensities and wavelet/Fourier coefficients using cosine correlation. The performance of the proposed approaches along with the existing similarity measures was evaluated using the NIST Chemistry WebBook mass database maintained by the National Institute of Standards and Technology (NIST) as a library of reference spectra and repetitive mass spectral data as query spectra. The analysis results showed that the identification accuracies of the wavelet- and Fourier-transform-based methods were improved by 2.02% and 1.95%, respectively, compared to that of the weighted dot product (cosine correlation) and by 3.01% and 3.08%, respectively, compared to that of the composite similarity measure. The improved identification accuracy demonstrates that the proposed approaches outperformed the existing similarity measures in the literature. PMID:21651237

  7. Wavelet and Fourier Transforms-based Spectrum Similarity Approaches to Compound Identification in Gas Chromatography Mass Spectrometry

    PubMed Central

    Koo, Imhoi; Zhang, Xiang; Kim, Seongho

    2011-01-01

    The high-throughput gas chromatography-mass spectrometry (GC-MS) technology offers a powerful means of analyzing a large number of chemical and biological samples. One of the important analyses of GC-MS data is compound identification. In this work, novel spectral similarity measures based on the discrete wavelet and Fourier transforms were proposed. The proposed methods are composite similarities that are composed of weighted intensities and wavelet/Fourier coefficients using cosine correlation. The performance of the proposed approaches along with the existing similarity measures was evaluated using the NIST Chemistry WebBook mass database maintained by the National Institute of Standards and Technology (NIST) as a library of reference spectra and repetitive mass spectral data as query spectra. The analysis results showed that the identification accuracies of the wavelet/Fourier transform-based methods were improved by 2.02% and 1.95%, respectively, comparing the weighted dot product (cosine correlation) and by 3.01% and 3.08%, respectively, comparing to the composite similarity measure. The improved identification accuracy demonstrates that the proposed approaches outperformed the existing similarity measures in the literature. PMID:21651237

  8. [Determination of alkylphenol and alkylphenolpolyethoxylates in brine by solid phase extraction and high performance liquid chromatography-mass spectrometry].

    PubMed

    Wang, Jincheng; Xiong, Li; Zhang, Haijun; Chen, Jiping

    2011-12-01

    A simple method based on solid phase extraction (SPE) coupled with high performance liquid chromatography-mass spectrometry (HPLC-MS) was developed for the determination of octylphenol (OP), nonylphenol (NP), octylphenol ethoxylates (OPEOs) and nonylphenol ethoxylates (NPEOs) in brine. The extraction and cleanup of brine samples were performed on C18 solid-phase extraction cartridges. The complete separation among OP, NP, OPEOs and NPEOs was achieved on a Hypersil GOLD analytical column with methanol-water as the mobile phase. The determination was achieved using HPLC-MS with electrospray ionization (ESI) in selected ion monitoring mode. The results showed that the average recoveries of target compounds were 59.6% - 104.4% and the corresponding relative standard deviations (RSDs, n = 3) were 1.0% - 13.5%. The instrumental limits of detection for the compounds were 0.08 - 3 microg/L. This method was applied to the analysis of the samples of seawater near Dalian coast. The results showed that both NP and NPEOs were detected in all samples and their concentrations in seaport and oil port were much higher than those in other sampling sites. PMID:22500440

  9. Determination of fecal sterols by gas chromatography-mass spectrometry with solid-phase extraction and injection-port derivatization.

    PubMed

    Wu, Jingming; Hu, Ruikang; Yue, Junqi; Yang, Zhaoguang; Zhang, Lifeng

    2009-02-13

    Injection-port derivatization combined with solid-phase extraction (SPE) was developed and applied for the first time to determine five types of fecal sterols (coprostanol, cholestanol, epicholestanol, epicoprostanol and cholesterol) with gas chromatography-mass spectrometry (GC-MS). In this method, silylation of fecal sterols was performed with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) at GC injection-port. The factors influential to this technique such as injection-port temperature, purge-off time, derivatization reagent (BSTFA) volume, and the type of organic solvent were investigated. In addition, the conditions of SPE (including the type of SPE cartridge, the type of elution organic solvent) were also studied. After SPE followed by injection-port silylation by GC-MS, good linearity of analytes was achieved in the range of 0.02-10ng/mL with coefficients of determination, R(2)>0.995. Good reproducibility was obtained with relative standard deviation less than 19.6%. The limits of detection ranged from 1.3ng/mL to 15ng/mL (S/N=3) in environmental water samples. Compared with traditional off-line silylation of fecal sterols performed with water bath (60 degrees C, 30min), this injection-port silylation method is much simpler and convenient. The developed method has been successfully applied for the analysis of fecal sterols from real environmental water samples. PMID:19147150

  10. 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.

  11. 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.

  12. Systematic analysis of glycerol: colourimetric screening and gas chromatography-mass spectrometric confirmation.

    PubMed

    Sardela, Vinícius F; Scalco, Fernanda B; Cavalcante, Karina M; Simoni, Ruth E; Silva, Deyvison R; Pereira, Henrique Marcelo G; de Oliveira, Maria Lúcia L Costa; Aquino Neto, Francisco R

    2015-10-01

    Glycerol is a naturally occurring polyol in the human body, essential for several metabolic processes. It is widely used in the food, pharmaceutical, and medical industries and in clinical practice as a plasma volume expander (PVE). Athletes, however, may use glycerol to mask the presence of forbidden substances or to enhance performance, inclusively through hyperhydration achieved by glycerol ingestion with added fluid. These practices are considered doping, and are prohibited by the World Anti-Doping Agency (WADA). Therefore, glycerol was introduced in the prohibited list. Doping through glycerol ingestion can readily be identified by detection of elevated glycerol concentrations in urine. In this paper, a protocol for the fast detection of glycerol in urine is proposed. It consists of a previous visual colourimetric screening, followed by a quantitative/qualitative confirmation analysis by mass spectrometry. The screening procedure involves a reaction in which polyhydric alcohols are oxidized by periodate to formic acid and formaldehyde, which is detected by the addition of a fuchsin solution. For the subsequent qualitative/quantitative confirmation analysis, a gas chromatography-mass spectrometry based approach with a non-deuterated internal standard and a drying step of only 10 min is proposed. The linear correlation was demonstrated within WADA´s threshold range. The calculated RSD were 2.1% for within-day precision and 2.8% for between-day precision. The uncertainty estimation was calculated, and a value of 2.7% was obtained. The procedure may also be used for the analysis of other polyols in urine, as for example the PVE mannitol. PMID:26112364

  13. Determination of alkyl anilines and alkyl pyridines in solvent refined coal distillates and aqueous extracts by gas chromatography/mass spectrometry

    SciTech Connect

    Felice, L.T.

    1982-05-01

    Derivatization with acetic anhydride in aqueous media coupled with capillary gas chromatography/mass spectrometry was used to distinguish alkyl anilines from alkyl pyridines. By use of this approach aniline, C-1 anilines, and C-2 anilines, as well as lesser quantities of C-2 pyridines and C-3 pyridines, were positively identified in a solvent refined coal (SRC-II) blended distillate and in an aqueous extract of the distillate. The extraction procedure and acetylation conditions employed were examined in detail and found suitable for quantitative analysis when combined with capillary gas chromatography.

  14. Mercapturic acids: recent advances in their determination by liquid chromatography/mass spectrometry and their use in toxicant metabolism studies and in occupational and environmental exposure studies.

    PubMed

    Mathias, Patricia I; B'hymer, Clayton

    2016-06-01

    This review describes recent selected HPLC/MS methods for the determination of urinary mercapturates that are useful as noninvasive biomarkers in characterizing human exposure to electrophilic industrial chemicals in occupational and environmental studies. High-performance liquid chromatography/mass spectrometry is a sensitive and specific method for analysis of small molecules found in biological fluids. In this review, recent selected mercapturate quantification methods are summarized and specific cases are presented. The biological formation of mercapturates is introduced and their use as indicators of metabolic processing of reactive toxicants is discussed, as well as future trends and limitations in this area of research. PMID:26900903

  15. 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

  16. Combination of direct infusion mass spectrometry and gas chromatography mass spectrometry for toxicometabolomic study of red blood cells and serum of mice Mus musculus after mercury exposure.

    PubMed

    García-Sevillano, M A; García-Barrera, T; Navarro, F; Abril, N; Pueyo, C; López-Barea, J; Gómez-Ariza, J L

    2015-03-15

    Although mercury (Hg) is an important environmental and occupational pollutant, its toxicological effects, especially in serum and red blood cells (RBCs), have been scarcely studied. A toxicometabolomics workflow based on high resolution mass spectrometry approaches has been applied to investigate the toxicological effects of Hg in Mus musculus mice after subcutaneous injection for 10 days, which produced inflammation and vacuolization, steatosis and karyolysis in the hepatic tissue. To this end, direct infusion mass spectrometry (DIMS) of polar and lipophilic extracts from serum and RBCs, using positive and negative mode of acquisition (ESI+/ESI-), and gas chromatography-mass spectrometry were used. A quantitative analysis of reversible oxidized thiols in serum proteins demonstrated a strong oxidative stress induction in the liver of Hg-exposed mice. Endogenous metabolites alterations were identified by partial least squares-discriminant analysis (PLS-DA). Mercury-exposed mice show perturbations in energy metabolism, amino acid metabolism, membrane phospholipid breakdown and oxidative stress-related metabolites in serum along the exposure. This work reports for the first time the effects of Hg-exposure on RBCs metabolic pathways, and reveals disturbances in glycolysis, membrane turnover, glutathione and ascorbate metabolisms. PMID:25660718

  17. The use of stable isotopes and gas chromatography/mass spectrometry in the identification of steroid metabolites in the equine

    SciTech Connect

    Houghton, E.; Dumasia, M.C.; Teale, P.; Smith, S.J.; Cox, J.; Marshall, D.; Gower, D.B. )

    1990-10-01

    Stable isotope gas chromatography/mass spectrometry has been used successfully in the elucidation of structures of urinary steroid metabolites in the horse and in the identification of metabolites isolated from in vivo perfusion and in vitro incubation studies using equine tissue preparations. Deuterium-labeled steroids, testosterone, dehydroepiandrosterone, and 5-androstene-3 beta,17 beta-diol have been synthesized by base-catalyzed isotope exchange methods and the products characterized by gas chromatography/mass spectrometry. (16,16(-2)H2)Dehydroepiandrosterone (plus radiolabeled dehydroepiandrosterone) was perfused into a testicular artery of a pony stallion and was shown to be metabolized into 2H2-labeled testosterone, 4-androstenedione, isomers of 5-androstene-3,17-diol, 19-hydroxytestosterone, and 19-hydroxy-4-androstenedione. In further studies, equine testicular minces have been incubated with 2H2-labeled and radiolabeled dehydroepiandrosterone and 5-androstene-3 beta, 17 beta-diol. The metabolites, whose identity was confirmed by stable isotope gas chromatography/mass spectrometry, proved the interconversion of the two substrates, as well as formation of testosterone and 4-androstenedione. The aromatization of dehydroepiandrosterone was also confirmed, together with the formation of an isomer of 5(10)-estrene-3,17-diol from both substrates showing 19-demethylation without concomitant aromatization. In studies of the feto-placental unit, the allantochorion was shown to aromatize (2H5)testosterone to (2H4)estradiol, the loss of one 2H from the substrate being consistent with aromatization of the A ring. The formation of 6-hydroxyestradiol was also confirmed in this study. The same technique has been valuable in determining the structure of two metabolites of nandrolone isolated from horse urine.

  18. Identification of Gibberellins in Norway Spruce (Picea abies [L.] Karst.) by Combined Gas Chromatography-Mass Spectrometry

    PubMed Central

    Odén, Per Christer; Schwenen, Ludger; Graebe, Jan E.

    1987-01-01

    Gibberellins A1 (GA1), A3 and A9 were identified from extracts of shoots of 6-month old Norway spruce (Picea abies) seedlings by the use of sequential reverse and normal phase high performance liquid chromatography (HPLC), bioassay, radioimmunoassay (RIA) and combined gas chromatography-mass spectrometry (GC-MS). The bioassay and RIA were used after fractionation by HPLC to detect the GA-containing fractions, which were then examined by GC-MS. The GAs identified are considered to be endogenous. PMID:16665471

  19. Application of capillary gas chromatography mass spectrometry/computer techniques to synoptic survey of organic material in bed sediment

    USGS Publications Warehouse

    Steinheimer, T.R.; Pereira, W.E.; Johnson, S.M.

    1981-01-01

    A bed sediment sample taken from an area impacted by heavy industrial activity was analyzed for organic compounds of environmental significance. Extraction was effected on a Soxhlet apparatus using a freeze-dried sample. The Soxhlet extract was fractionated by silica gel micro-column adsorption chromatography. Separation and identification of the organic compounds was accomplished by capillary gas chromatography/mass spectrometry techniques. More than 50 compounds were identified; these include saturated hydrocarbons, olefins, aromatic hydrocarbons, alkylated polycyclic aromatic hydrocarbons, and oxygenated compounds such as aldehydes and ketones. The role of bed sediments as a source or sink for organic pollutants is discussed. ?? 1981.

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

    PubMed Central

    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