Sample records for gas chromatography-mass spectrophotometry

  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. ORGANIC WATER POLLUTANT ANALYSIS BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY

    EPA Science Inventory

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

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

    Microsoft Academic Search

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

    2008-01-01

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

  4. 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.

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

    PubMed

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

    1977-01-01

    Unknown compounds detected in Ardea herodias tissues are identified by gas-liquid chromatography-mass spectrometry as residues of octachlorostyrene. Heptachlorostyrene and hexachlorostyrene were tentatively identified. PMID:833106

  6. 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...

  7. 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.

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

    E-print Network

    Antoniewicz, Maciek R.

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

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

    PubMed

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

    2008-06-20

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

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

    EPA Science Inventory

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

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

    Microsoft Academic Search

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

    1987-01-01

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

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

    Microsoft Academic Search

    Carine Marinach; Marie-Christine Papillon; Claude Pepe

    2004-01-01

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

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

    Microsoft Academic Search

    Sadao Nakamura; Masahiko Takino; Shigeki Daishima

    2001-01-01

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

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

    Microsoft Academic Search

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

    2007-01-01

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

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

    PubMed

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

    2006-08-01

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

  16. Chemical discrimination in turbulent gas mixtures with MOX sensors validated by gas chromatography-mass spectrometry.

    PubMed

    Fonollosa, Jordi; Rodríguez-Luján, Irene; Trincavelli, Marco; Vergara, Alexander; Huerta, Ramón

    2014-01-01

    Chemical detection systems based on chemo-resistive sensors usually include a gas chamber to control the sample air flow and to minimize turbulence. However, such a kind of experimental setup does not reproduce the gas concentration fluctuations observed in natural environments and destroys the spatio-temporal information contained in gas plumes. Aiming at reproducing more realistic environments, we utilize a wind tunnel with two independent gas sources that get naturally mixed along a turbulent flow. For the first time, chemo-resistive gas sensors are exposed to dynamic gas mixtures generated with several concentration levels at the sources. Moreover, the ground truth of gas concentrations at the sensor location was estimated by means of gas chromatography-mass spectrometry. We used a support vector machine as a tool to show that chemo-resistive transduction can be utilized to reliably identify chemical components in dynamic turbulent mixtures, as long as sufficient gas concentration coverage is used. We show that in open sampling systems, training the classifiers only on high concentrations of gases produces less effective classification and that it is important to calibrate the classification method with data at low gas concentrations to achieve optimal performance. PMID:25325339

  17. Determination of Alkyl Methanesulfonates in Doxazosin Mesylate by Gas Chromatography-mass Spectrometer

    PubMed Central

    Sitaram, C.; Rupakula, R. B.; Reddy, B. N.; Sastry, C. S. P

    2011-01-01

    High sensitive rapid gas chromatography-mass spectrometry method for the determination of four carcinogenic alkyl methanesulfonates viz. methyl methanesulfonate, ethyl methanesulfonate, isopropyl methanesulfonate and n-butyl methanesulfonate in doxazosin mesylate has been presented by using selective ion monitoring mode. The optimum separation was achieved between methyl methanesulfonate, ethyl methanesulfonate, isopropyl methanesulfonate and n-butyl methanesulfonate on a DB-5 (30 m×0.32 mm×1.0 ?m) capillary column under programming temperature. Acetonitrile, water and ammonia (90:9:1 v/v/v) mixture was used as diluent. Various factors involved in the gas chromatography-mass spectrometry method development are also presented. This method was validated as per International Conference on Harmonization guidelines. The limit of quantitation of methyl methanesulfonate, ethyl methanesulfonate, isopropyl methanesulfonate and n-butyl methanesulfonate is 6 ppm with respect to 30 mg/ml of doxazosin mesylate. PMID:22131634

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

    PubMed

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

    2015-01-01

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

  19. [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

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

    Microsoft Academic Search

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

    1998-01-01

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

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

    Microsoft Academic Search

    Rong Lu; Yukio Kamiya; Tetsuo Miyakoshi

    2006-01-01

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

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

    Microsoft Academic Search

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

    2006-01-01

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

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

    Microsoft Academic Search

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

    1968-01-01

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

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

    Microsoft Academic Search

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

    1997-01-01

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

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

    Microsoft Academic Search

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

    2007-01-01

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

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

    Microsoft Academic Search

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

    2001-01-01

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

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

    Microsoft Academic Search

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

    2001-01-01

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

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

    Microsoft Academic Search

    Patricia M. Medeiros; Bernd R. T. Simoneit

    2007-01-01

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

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

    Microsoft Academic Search

    Tzvi Shahar; Shai Dagan; Aviv Amirav

    1998-01-01

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

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

    Microsoft Academic Search

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

    2006-01-01

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

  11. Simultaneous Determination of Nalbuphine and Opiates in Human Hair by Gas Chromatography-Mass Spectrometry

    Microsoft Academic Search

    Jin Young Kim; Moon Kyo In; Ki-Jung Paeng; Bong Chul Chung

    2004-01-01

    The method for simultaneous determination of nalbuphine and opiates (codeine, morphine, and 6-monoacetylmorphine) in human hair was developed in the selected-ion monitoring (SIM) mode of a gas chromatography-mass spectrometer (GC-MS). Thirty-milligram hair samples were incubated in 0.01 M HCl overnight at 50 °C. We extracted the drugs from resulting hydrolyzed solutions with a mixture of chloroform-isopropanol- n-heptane (50:17:33, v\\/ v\\/

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

    Microsoft Academic Search

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

    2002-01-01

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

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

    Microsoft Academic Search

    Ruikang Hu; Lifeng Zhang; Zhaoguang Yang

    2008-01-01

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

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

    Microsoft Academic Search

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

    2002-01-01

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

  15. 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.

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

    Microsoft Academic Search

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

    2010-01-01

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

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

    Microsoft Academic Search

    Yuri A Blednov; Victoria J Simpson

    1999-01-01

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

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

    Microsoft Academic Search

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

    1995-01-01

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

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

    Microsoft Academic Search

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

    2008-01-01

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

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

    Microsoft Academic Search

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

    2010-01-01

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

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

    Microsoft Academic Search

    PATRICK G. HATCHER

    1998-01-01

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

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

    SciTech Connect

    Shen, J.

    1981-03-01

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

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

    Microsoft Academic Search

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

    2007-01-01

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

  4. 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

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

    Microsoft Academic Search

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

    2010-01-01

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

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

    PubMed

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

    2009-03-01

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

  7. A Low Thermal Mass Fast Gas Chromatograph and its Implementation in Fast Gas Chromatography Mass Spectrometry with Supersonic Molecular Beams

    Microsoft Academic Search

    Alexander B. Fialkov; Mati Moragn; Aviv Amirav

    A new type of low thermal mass (LTM) fast gas chromatograph (GC) was designed and operated in combination with gas chromatography mass spectrometry (GC-MS) with supersonic molecular beams (SMB), including GC-MS-MS with SMB, thereby providing a novel combination with unique capabilities. The LTM fast GC is based on a short capillary column inserted inside a stainless steel tube that is

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

    PubMed

    Kage, Shigetoshi; Kudo, Keiko; Ikeda, Noriaki

    2002-09-01

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

  9. 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

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

    PubMed

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

    2015-01-01

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

  11. Routine analysis of plasma busulfan by gas chromatography-mass fragmentography.

    PubMed

    Lai, W K; Pang, C P; Law, L K; Wong, R; Li, C K; Yuen, P M

    1998-12-01

    Busulfan (BU) is a widely used alkylating agent for antineoplastic therapy and marrow ablation in preparation for bone marrow transplantation (BMT). High-dose BU often leads to successful preparation and low relapse but is associated with veno-occlusive disease of liver. We established a protocol to determine postdosage plasma BU concentrations by gas chromatography-mass fragmentography in an attempt to relate clinical outcome to plasma BU concentrations. We used nonisotopic pusulfan as the internal standard. After extraction into ethyl acetate, BU and pusulfan were iodinated into 1, 4-diiodobutane and 1,5-diiodopentane, respectively. Gas chromatography-mass spectrometry (GC-MS) analysis was carried out on an Hewlett-Packard (HP) 5890II gas chromatograph with a 30-m 100% methyl silicon narrow bore, fused-silica capillary column interfaced with an HP 5970A mass spectrometer. Helium was the carrier gas. The sample molecules were identified by total ion monitoring and quantified by selective ion monitoring of m/z 183 and 197. The calibration curve was linear to 4 mg/L. The limit of quantification was 0.04 mg/L, and the analytical recovery was approximately 97%. The within-day and between-day imprecision (CV) was <6% and 9%, respectively. In a preliminary study of 12 children, the BU areas under the BU-time curve were 616-949 micromol. min/L after the first dose and 793-1143 micromol. min/L after the fifth dose. We conclude that the GC-MS procedure is suitable for routine analysis of plasma BU. PMID:9836718

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

    PubMed

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

    1994-03-01

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

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

    PubMed

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

    2002-11-25

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

  14. 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.

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

    PubMed

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

    2006-04-13

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

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

    PubMed

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

    2011-05-01

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

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

    PubMed

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

    2011-09-28

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

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed Central

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

    2014-01-01

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

  20. 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

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

    PubMed

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

    2015-05-01

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

  2. 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....

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

    Microsoft Academic Search

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

    2003-01-01

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

  4. Gas Chromatography-Mass Spectroscopy Study of tert-Butylarsine Stability and Purification

    SciTech Connect

    Bartram, M.E.; Breiland, W.G.; Bruskas, L.A.; Killeen, K.P.

    1999-07-20

    TBA (tert-butylarsine, H{sub 2}AsC(CH{sub 3}){sub 3}) has been demonstrated to be an effective arsenic precursor for the deposition of compound semiconductors such as GaAs by MOCVD (metal organic chemical vapor deposition). TBA is used as a liquid (bubbler) source in MOCVD and is a less toxic alternative to the more commonly used gaseous arsine (AsH{sub 3}). Materials and device performance using TBA have in many cases equaled or surpassed those using arsine. This includes the first observation of fractional quantum Hall behavior in a two dimensional electron gas structure grown by MOCVD. Despite the beneficial characteristics, the use of TBA in our laboratories has revealed some inconsistent behavior. Small pressure rises have been observed in the TBA bubbler sources when left unused over a period of many days. Measurements of the TBA partial pressure using UV absorption revealed that new absorption peaks could be observed after storage. The features of the absorption profile were insufficient to ascribe to a specific chemical species. Attempts to remove the gaseous impurities with liquid nitrogen freeze-pump-thaw techniques had limited success. Unfortunately, there is no published information on the room temperature decomposition of TBA. In this paper, we present a series of GCMS (gas chromatography-mass spectroscopy) analyses designed to determine the stability of TBA and identify its decomposition products in storage containers. The GCMS is also used to evaluate several methods for in-situ purification of TBA.

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

    PubMed

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

    2007-02-01

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

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

    PubMed

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

    1988-02-26

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

  7. Occurrence of short chain aliphatic diols in human blood: identification by gas chromatography-mass spectrometry.

    PubMed

    Sisfontes, L; Nyborg, G; Jones, A W; Blomstrand, R

    1986-03-16

    Patients attending a general hospital for various reasons were screened for raised serum gamma glutamyltransferase (gamma-GT) and positive blood alcohol concentration (BAC). The results served as objective biochemical tests of heavy drinking. Among 419 individuals, 50 (11.9%) met these requirements and blood samples were used to determine the presence of low molecular mass aliphatic diols. 1,2-Propanediol, 2,3-butanediol and 2,2-dimethyl-1,3-propanediol were determined by gas liquid chromatography-mass spectrometry (GC-MS). In patients with blood ethanol concentration less than 2 mmol/l, 1,2-propanediol and 2,2-dimethyl-1, 3-propanediol mainly occurred together at median concentrations of about 200 mumol/l. When blood ethanol was 2-42 mmol/1,2,3-butanediol was also present covering a wide concentration range: three patients had concentrations between 6 and 10 mmol/l. There was no apparent correlation between the concentration of 2,3-butanediol and the concentration of blood ethanol. The diols were below the limits of detection in blood from nonintoxicated control individuals and hospital in-patients. PMID:3698310

  8. Quantification of busulfan in plasma by gas chromatography-mass spectrometry following derivatization with tetrafluorothiophenol.

    PubMed

    Quernin, M H; Poonkuzhali, B; Montes, C; Krishnamoorthy, R; Dennison, D; Srivastava, A; Vilmer, E; Chandy, M; Jacqz-Aigrain, E

    1998-05-01

    A specific and highly sensitive method has been developed for the determination of busulfan in plasma by gas chromatography-mass spectrometry using a deuterium-labeled busulfan (busulfan-d8) as internal standard. Plasma containing busulfan and busulfan-d8 were extracted with ethyl acetate and derivatized with 2,3,5,6-tetrafluorothiophenol prior to the monitoring of specific ions. The limit of quantification of the assay was 20 ng/ml and the calibration curve was linear over the range of 10 to 2000 ng/ml of derivatized busulfan. This method was in good agreement with the GC-MS assay using derivatization with sodium iodide and measuring diiodobutane. In addition, a pharmacokinetic study of busulfan was conducted in six children. The apparent oral clearance was 5.7+/-1.9 ml/kg/min and the volume of distribution was 1.0+/-0.4 l/kg and were similar to those previously reported in pediatric patients. PMID:9653925

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

    PubMed

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

    2001-10-01

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

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

    PubMed

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

    2010-11-01

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

  11. [15N]aspartate metabolism in cultured astrocytes. Studies with gas chromatography-mass spectrometry.

    PubMed Central

    Yudkoff, M; Nissim, I; Pleasure, D

    1987-01-01

    The metabolism of 2.5 mM-[15N]aspartate in cultured astrocytes was studied with gas chromatography-mass spectrometry. Three primary metabolic pathways of aspartate nitrogen disposition were identified: transamination with 2-oxoglutarate to form [15N]glutamate, the nitrogen of which subsequently was transferred to glutamine, alanine, serine and ornithine; condensation with IMP in the first step of the purine nucleotide cycle, the aspartate nitrogen appearing as [6-amino-15N]adenine nucleotides; condensation with citrulline to form argininosuccinate, which is cleaved to yield [15N]arginine. Of these three pathways, the formation of arginine was quantitatively the most important, and net nitrogen flux to arginine was greater than flux to other amino acids, including glutamine. Notwithstanding the large amount of [15N]arginine produced, essentially no [15N]urea was measured. Addition of NaH13CO3 to the astrocyte culture medium was associated with the formation of [13C]citrulline, thus confirming that these cells are capable of citrulline synthesis de novo. When astrocytes were incubated with a lower (0.05 mM) concentration of [15N]aspartate, most 15N was recovered in alanine, glutamine and arginine. Formation of [6-amino-15N]adenine nucleotides was diminished markedly compared with results obtained in the presence of 2.5 mM-[15N]aspartate. PMID:3032154

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

    PubMed

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

    2007-09-14

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

  13. 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.

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

    PubMed

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

    2013-01-18

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

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

    PubMed

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

    2013-09-10

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

  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. 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

  18. [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

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

    PubMed Central

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

    2014-01-01

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

  20. Gas chromatography-mass spectrometry/selected ion monitoring for screening asymmetric epoxidation of styrene.

    PubMed

    Mu, Yao; Wei, Siping; Xu, Min; Chen, Ping; Wang, Qin; Du, Xi

    2014-12-01

    A screening method by gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring (SIM) has been developed for asymmetric epoxidation of styrene. All samples were analyzed by GC-MS with the mode of SIM by using ethylbenzene as the internal standard, by which styrene and styrene epoxide enantiomers were completely separated and their concentrations were accurately determined. Furthermore, this method was used to evaluate the epoxidation reaction of styrene, which was optimized by orthogonal experiment. The advantages of the method are as follows: excellent precision (RSD in the range of 1. 2% - 5. 2%, n= 5), good linearity (the correlation coefficients for styrene, (R)/(S)-styrene oxide were 0. 9997, 0. 9932 and 0. 9963, respectively) , low limits of quantitation (LOQs of styrene, (R)/(S)-styrene oxide were 1. 3, 1. 1 and 0. 7 mg/L, respectively) and reasonable recoveries (98. 2% - 108. 2%). All in all, the method provided a new way to determine the asymmetric epoxidation mixture of styrene and its homologs. PMID:25902648

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

    PubMed

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

    2013-01-10

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

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

    PubMed

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

    2012-05-01

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

  3. Determination of ajulemic acid and its glucuronide in human plasma by gas chromatography-mass spectrometry.

    PubMed

    Batista, Catarina; Berisha, Myftar; Karst, Matthias; Salim, Kahlid; Schneider, Udo; Brenneisen, Rudolf

    2005-06-01

    A method using gas chromatography-mass spectrometry (GC-MS) and solid-phase extraction (SPE) was developed for the determination of ajulemic acid (AJA), a non-psychoactive synthetic cannabinoid with interesting therapeutic potential, in human plasma. When using two calibration graphs, the assay linearity ranged from 10 to 750 ng/ml, and 750 to 3000 ng/ml AJA. The intra- and inter-day precision (R.S.D., %), assessed across the linear ranges of the assay, was between 1.5 and 7.0, and 3.6 and 7.9, respectively. The limit of quantitation (LOQ) was 10 ng/ml. The amount of AJA glucuronide was determined by calculating the difference in the AJA concentration before ("free AJA") and after enzymatic hydrolysis ("total AJA"). The present method was used within a clinical study on 21 patients suffering from neuropathic pain with hyperalgesia and allodynia. For example, plasma levels of 599.4+/-37.2 ng/ml (mean+/-R.S.D., n=9) AJA were obtained for samples taken 2 h after the administration of an oral dose of 20 mg AJA. The mean AJA glucuronide concentration at 2h was 63.8+/-127.9 ng/ml. PMID:15866495

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

    PubMed

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

    2013-08-01

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

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

    PubMed

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

    1984-07-01

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

  6. Magnetic solid phase extraction and gas chromatography-mass spectrometrical analysis of sixteen polycyclic aromatic hydrocarbons.

    PubMed

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

    2015-08-01

    Fluorenyl functionalized superparamagnetic core/shell magnetic nanoparticles (MNPs, Fe3O4@SiO2@Flu) were prepared and characterized by transmission electron microscope, X-ray diffraction and infrared spectroscopy. The MNPs having an average diameter of 200nm were then used as solid-phase extraction sorbent for the determination of 16 priority pollutants polycyclic aromatic hydrocarbons (PAHs) in water samples designated by United States Environmental Protection Agency (U.S. EPA). The main influencing parameters, including sorbent amount, desorption solvent, sample volume and extraction time were optimized. Analyses were performed on gas chromatography-mass spectrometry (GC-MS) using selected ion monitoring (SIM) mode. Method validation proved the feasibility of the developed sorbents for the quantitation of the investigated analytes at trace levels. Limit of detection ranging from 0.5 to 4.0ng/L were obtained. The repeatability was investigated by evaluating the intra- and inter-day precisions with relative standard deviations (RSDs) lower than 13.1%. Finally, the proposed method was successfully applied for the determination of PAHs in water samples with the recoveries in the range of 96.0-106.7%. PMID:26122856

  7. 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.

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

    PubMed Central

    2014-01-01

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

  9. 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

  10. Analytical method for the determination of strychnine in tissues by gas chromatography\\/mass spectrometry: two case reports

    Microsoft Academic Search

    E. P. Marques; F. Gil; P. Proença; P. Monsanto; M. F. Oliveira; A. Castanheira; D. N. Vieira

    2000-01-01

    This paper describes an analytical method for strychnine determination in biological samples by gas chromatography\\/mass spectrometry and their application in the investigation of two cases involving strychnine ingestion: A fatal case and a clinical one. The strychnine is isolated from biological samples using a liquid–liquid extraction procedure. The clean-up procedure is performed using an acid solution. Papaverine is used as

  11. Novel pyrolysis-gas chromatography\\/mass spectrometric techniques for the characterization of chemical additives in portland cement and concrete

    Microsoft Academic Search

    Ara A. Jeknavorian; E. F. Barry; J. J. Litzau

    1998-01-01

    The application of pyrolysis gas chromatography mass spectrometry (py-GC\\/MS) has been improved for the determination of chemical additives that are either interground with cement clinker during the manufacture of Portland cement or admixed with a mixture of cement, sand, and stone, and water for the production of concrete. This technique has been found to be readily applicable for phenol-based cement

  12. Identification of monoacyl- and monoalkylglycerols by gas-liquid chromatography-mass spectrometry using polar siloxane liquid phases

    Microsoft Academic Search

    J. J. Myher; L. Marai; A. Kuksis

    A comparative study was made of the spectra ob- tained after gas-liquid chromatography-mass spectrometry of the trimethylsilyl ethers of 1- and 2-monoacyl- and monoalkyl- glycerols. The glycerol derivatives were resolved on the basis of positional substitution and the degree of unsaturation on Silar- 5CP (a cyanopropylphenylsiloxane) liquid phase, and the peaks were examined in a Varian MAT CH-5 single-focusing mass

  13. Pyrolysis-Gas Chromatography\\/Mass Spectrometry Identifi cation of Distinctive Structures Providing Humic Character to Organic Materials

    Microsoft Academic Search

    Marta Fuentes; Roberto Baigorri; Francisco J. González-Vila; José M. García-Mina

    Flash pyrolysis-gas chromatography\\/mass spectrometry (Py- GC\\/MS) was used to study the structural transformations of humic fractions formed as a result of composting processes of diverse organic materials (solid wastes of wineries, solid olive- mill wastes, domestic wastes, ovine manures plus straw, and mixtures of animal manures). Sodium hydroxide-extracted total humic-like extracts (THE; humic plus fulvic acids) from the composted and

  14. Microstructure characterization of acetylenic polymers by Curie-point pyrolysis\\/capillary gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    Sandrine Duc; Alain Petit

    1997-01-01

    The degradation of homo- and copolymers of 1-hexyne and phenylacetylene synthesized with a Ziegler-Natta initiating system and a metathesis catalyst have been investigated by pyrolysis-gas chromatography\\/mass spectrometry (Py-GC\\/MS) in order to describe the monomer arrangement in the macromolecular chains. The experiments were performed at 500°C using a Curie-point pyrolyzer and the products were separated by means of a capillary column

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

    Microsoft Academic Search

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

    2012-01-01

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

  16. Preparation and characterization of Melanorrhoea usitata lacquer film based on pyrolysis–gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    Rong Lu; Yukio Kamiya; Tetsuo Miyakoshi

    2007-01-01

    3-(10-Phenyldecyl)catechol was synthesized by the reaction of catechol and 1-phenyl-10-iododecane, followed by de-protection of the hydroxyl groups of catechol; it was then polymerized into synthetic lacquer film by laccase enzyme, and characterized using pyrolysis–gas chromatography\\/mass spectrometry (Py–GC\\/MS) in order to reveal the polymerization mechanism of Melanorrhoea usitata lacquer. The molecular weight and molecular structure information for each peak in the

  17. Characterization of amino acids and proteinaceous materials using online tetramethylammonium hydroxide (TMAH) thermochemolysis and gas chromatography-mass spectrometry technique

    Microsoft Academic Search

    Xu Zang; Johnie C Brown; Jasper D. H van Heemst; Amanda Palumbo; Patrick G Hatcher

    2001-01-01

    An on-line thermochemolysis technique using tetramethylammonium hydroxide (TMAH) for the characterization of amino acids and proteinaceous materials was developed. Amino acids were converted to their corresponding N-and O-methyl derivatives by TMAH in the pyrolysis chamber for 15 s at 300°C prior to separation and detection by gas chromatography-mass spectrometry. Thermochemolysis reactions of TMAH with protein and macromolecular environmental sample were

  18. Characterization of kenaf ( Hibiscus cannabinus) lignin by pyrolysis-gas chromatography-mass spectrometry in the presence of tetramethylammonium hydroxide

    Microsoft Academic Search

    Ken-ichi Kuroda; Akiko Izumi; Bibhuti B Mazumder; Yoshito Ohtani; Kazuhiko Sameshima

    2002-01-01

    Pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) in the presence of tetramethylammonium hydroxide (TMAH) was applied to kenaf (Hibiscus cannabinus) fibers in order to clarify the chemical composition of in situ lignin. The core and bast samples obtained from the middle position of variety Chinpi-3 were pyrolyzed at 500°C for 4 s with TMAH. The core pyrogram revealed peaks retaining the structural attributes

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

    Microsoft Academic Search

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

    2007-01-01

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

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

    Microsoft Academic Search

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

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

  1. Development and validation of a gas chromatography–mass spectrometry assay for opiates and cocaine in human teeth

    Microsoft Academic Search

    Manuela Pellegrini; Adriana Casá; Emilia Marchei; Roberta Pacifici; Ruth Mayné; Vanessa Barbero; Oscar Garcia-Algar; Simona Pichini

    2006-01-01

    A procedure based on gas chromatography–mass spectrometry (GC–MS) is described for determination of opiates (6-monoacetylmorphine, morphine and codeine) and cocaine and metabolites (cocaine, benzoylecgonine and cocaethylene) in human teeth. After addition of nalorphine as internal standard, pulverized samples were incubated in HCl at 37°C for 18h. Then, after pH adjustment to 6, and the analytes were extracted with two volumes

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

    Microsoft Academic Search

    C. G Zambonin; A Cilenti; F Palmisano

    2002-01-01

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

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

    Microsoft Academic Search

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

    2010-01-01

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

  4. Use of gas chromatography-mass spectrometry\\/solid phase microextraction for the identification of MVOCs from moldy building materials

    Microsoft Academic Search

    Loay Wady; Annicka Bunte; Christina Pehrson; Lennart Larsson

    2003-01-01

    Gas chromatography-mass spectrometry\\/solid phase microextraction (GC-MS\\/SPME) was applied to identify microbial volatile organic compounds (MVOCs) in water-damaged, mold-infested building materials (gypsum board papers (n=2), mineral wool, and masonite) and in cultivated molds (Aspergillus penicillioides, Stachybotrys chartarum, and Chaetomium globosum). Three SPME fibers (65-?m PDMS-DVB, 75-?m Carboxen-PDMS, and 70-?m Carbowax-stableflex) designed for automated injection were used of which the latter showed

  5. Characterization of humic substances in highly polluted river sediments by pyrolysis methylation–gas chromatography–mass spectrometry

    Microsoft Academic Search

    Laurence Mansuy; Yassine Bourezgui; Evelyne Garnier-Zarli; Emilie Jardé; Véronique Réveillé

    2001-01-01

    Humic substances were extracted from two sediment cores sampled in a river on the outskirts of a large city (Deûle near Lille, France) and in its highly polluted oxbow-lake. Humic acids (HA) were characterized by infrared spectroscopy and in situ pyrolysis\\/methylation–gas chromatography–mass spectrometry. The main results are the substantial aliphaticity of HA in the oxbow-lake at all depths, mainly due

  6. Comparative study of extraction techniques for determination of garlic flavor components by gas chromatography–mass spectrometry

    Microsoft Academic Search

    Sun-Neo Lee; Nam-Sun Kim; Dong-Sun Lee

    2003-01-01

    Several sampling techniques based on steam distillation (SD), simultaneous distillation and solvent extraction (SDE), solid-phase trapping solvent extraction (SPTE), and headspace solid-phase microextraction (HS-SPME) have been compared for the determination of Korean garlic flavor components by gas chromatography–mass spectrometry (GC–MS). Diallyl disulfide (57.88%), allyl sulfide (23.59%), and diallyl trisulfide (11.40%) were found to be the predominant flavor components of garlic

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

    Microsoft Academic Search

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

    2010-01-01

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

  8. 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

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

    Microsoft Academic Search

    J Masteli?; I Jerkovi?

    2003-01-01

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

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

    Microsoft Academic Search

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

    1999-01-01

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

  11. A dynamic programming approach for the alignment of signal peaks in multiple gas chromatography-mass spectrometry experiments

    Microsoft Academic Search

    Mark D. Robinson; David P. De Souza; Woon Wai Keen; Eleanor C. Saunders; Malcolm J. Mcconville; Terence P. Speed; Vladimir A. Likic

    2007-01-01

    Background: Gas chromatography-mass spectrometry (GC-MS) is a robust platform for the profiling of certain classes of small molecules in biological samples. When multiple samples are profiled, including replicates of the same sample and\\/or different sample states, one needs to account for retention time drifts between experiments. This can be achieved either by the alignment of chromatographic profiles prior to peak

  12. The automation of the acquisition and evaluation of pyrolysis-gas chromatography–mass spectrometry data for paint samples

    Microsoft Academic Search

    D. Thorburn Burns; K. P. Doolan

    2006-01-01

    The evaluation is described of an automated pyrolysis-gas chromatography–mass spectrometry system combined with a software package to convert total ion current chromatograms into forms that resemble a conventional mass spectra called “spectragrams”. The spectragram for a single paint sample can be “closest fit” matched to a previously created paint pyrogram library via pre-determined target compounds in a handling list. Up

  13. Identification and quantification of the indole alkaloid ibogaine in biological samples by gas chromatography-mass spectrometry

    Microsoft Academic Search

    Carol A. Gallagher; Lindsay B. Hough; Sandra M. Keefner; Ahmad Seyed-Mozaffari; Sydney Archer

    1995-01-01

    A sensitive and highly selective analytical chemical method for measuring the indole alkaloid ibogaine in biological samples has been developed. The method utilizes organic extraction, derivatization with trifluoroacetic anhydride, and detection by combined gas chromatography-mass spectrometry. The deuterated analog of ibogaine, O-[Cd3]-ibogaine, was synthesized and used as an internal standard for the method. Standard curves, constructed from variable amounts of

  14. Rapid determination of cyanide in human plasma and urine by gas chromatography–mass spectrometry with two-step derivatization

    Microsoft Academic Search

    Guojie Liu; Junting Liu; Kenji Hara; Yanfang Wang; Yanping Yu; Lina Gao; Ling Li

    2009-01-01

    Cyanide (CN) is a powerful poison and rapidly toxic agent. Because of its wide availability and high toxicity, quantification of CN in blood and urine is frequently required in clinical and forensic practice. We present a sensitive and less time consuming method based on solid-supported liquid–liquid extraction (SLE) and gas chromatography–mass spectrometry (GC–MS) with two-step derivatization for determination of CN

  15. 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

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

    PubMed

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

    2009-09-01

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

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

    PubMed Central

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

    2009-01-01

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

  18. Chemometric Profile of Root Extracts of Rhodiola imbricata Edgew. with Hyphenated Gas Chromatography Mass Spectrometric Technique

    PubMed Central

    Tayade, Amol B.; Dhar, Priyanka; Kumar, Jatinder; Sharma, Manu; Chauhan, Rajinder S.; Chaurasia, Om P.; Srivastava, Ravi B.

    2013-01-01

    Rhodiola imbricata Edgew. (Rose root or Arctic root or Golden root or Shrolo), belonging to the family Crassulaceae, is an important food crop and medicinal plant in the Indian trans-Himalayan cold desert. Chemometric profile of the n-hexane, chloroform, dichloroethane, ethyl acetate, methanol, and 60% ethanol root extracts of R. imbricata were performed by hyphenated gas chromatography mass spectrometry (GC/MS) technique. GC/MS analysis was carried out using Thermo Finnigan PolarisQ Ion Trap GC/MS MS system comprising of an AS2000 liquid autosampler. Interpretation on mass spectrum of GC/MS was done using the NIST/EPA/NIH Mass Spectral Database, with NIST MS search program v.2.0g. Chemometric profile of root extracts revealed the presence of 63 phyto-chemotypes, among them, 1-pentacosanol; stigmast-5-en-3-ol, (3?,24S); 1-teracosanol; 1-henteracontanol; 17-pentatriacontene; 13-tetradecen-1-ol acetate; methyl tri-butyl ammonium chloride; bis(2-ethylhexyl) phthalate; 7,8-dimethylbenzocyclooctene; ethyl linoleate; 3-methoxy-5-methylphenol; hexadecanoic acid; camphor; 1,3-dimethoxybenzene; thujone; 1,3-benzenediol, 5-pentadecyl; benzenemethanol, 3-hydroxy, 5-methoxy; cholest-4-ene-3,6-dione; dodecanoic acid, 3-hydroxy; octadecane, 1-chloro; ethanone, 1-(4-hydroxyphenyl); ?-tocopherol; ascaridole; campesterol; 1-dotriacontane; heptadecane, 9-hexyl were found to be present in major amount. Eventually, in the present study we have found phytosterols, terpenoids, fatty acids, fatty acid esters, alkyl halides, phenols, alcohols, ethers, alkanes, and alkenes as the major group of phyto-chemotypes in the different root extracts of R. imbricata. All these compounds identified by GC/MS analysis were further investigated for their biological activities and it was found that they possess a diverse range of positive pharmacological actions. In future, isolation of individual phyto-chemotypes and subjecting them to biological activity will definitely prove fruitful results in designing a novel drug. PMID:23326358

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

    PubMed

    Guo, Liang; Lee, Hian Kee

    2014-04-15

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

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

    E-print Network

    Clewis, Suenda Beth

    1995-01-01

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

  1. Structural investigation of isolated aquatic fulvic and humic acids in seepage water of waste deposits by pyrolysis-gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    Franz-Josef Göbbels; Wilhelm Püttmann

    1997-01-01

    Fulvic and humic acids isolated from seepage waters of four municipal waste landfills and one hazardous waste landfill were analysed by Curie point pyrolysis-gas chromatography\\/mass spectrometry (Py?GCMS). Furthermore, fulvic and humic acids were subjected to acid hydrolysis followed by alkaline hydrolysis. The hydrolysis products were analysed by gas chromatography\\/mass spectrometry (GCMS) and the residues by Py?GCMS. Results show that the

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

    PubMed

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

    2005-12-01

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

  3. 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.

  4. A simple and reliable procedure for the determination of psychoactive drugs in oral fluid by gas chromatography–mass spectrometry

    Microsoft Academic Search

    Mitona Pujadas; Simona Pichini; Ester Civit; Elena Santamariña; Katherine Perez; Rafael de la Torre

    2007-01-01

    A simple and reliable gas chromatography–mass spectrometry method for identifying and quantifying psychoactive drugs in oral fluid is described. Substances under investigation were: psychostimulant drugs (amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine, 3,4-methylenedioxiamphetamine, 3,4-methylenedioxy-N-ethylamphetamine, phentermine), cocaine and metabolites (benzoylecgonine, cocaethylene, and ecgonine methyl esther), cannabinoids (delta-9-tetrahydrocannabinol, 11-nor-9-carboxy-delta-9-tetrahydrocannabinol, 11-hydroxy-delta-9-tetrahydrocannabinol, cannabinol and cannabidiol), opiates (6-monoacetylmorphine, morphine and codeine), hypnotics (flurazepam, flunitrazepam, dipotassium chlorazepate, alprazolam, diazepam and

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

    E-print Network

    Simpson, John Thomas

    1989-01-01

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

  6. Spectrophotometry

    NSDL National Science Digital Library

    David N. Blauch

    As part of a larger set of virtual lab experiments, this site specifically deals with the fundamentals of spectrophotometry The user may explore: 1) Absorbance Spectrum 2) Effect of Cell Path Length; 3)Effect of Concentration; 4) Beer's Law (where absorbance as a function of concentration provides insight on the molar absorptivity); 5) The construction of a calibration curve enables Analysis of an Unknown Solution.

  7. Determination of thiodiglycol, a mustard gas hydrolysis product by gas chromatography-mass spectrometry after tert-butyldimethylsilylation.

    PubMed

    Ohsawa, Isaac; Kanamori-Kataoka, Mieko; Tsuge, Kouichiro; Seto, Yasuo

    2004-12-24

    A method for determining thiodiglycol (TDG), a mustard gas hydrolysis product in water, serum and urine samples using gas chromatography-mass spectrometry (GC-MS) after tert-butyldimethylsilylation (TBDMS) is described. Quantitation of TDG was performed by measuring the respective peak area on the extracted ion chromatogram of m/z 293, using an internal standard, the TDG homologue, thiodipropanol, peak area of which was measured as m/z 321. The presence of salts in the sample solution not only suppressed the loss of TDG by vaporization during the evaporation of water, but also facilitated the rate of production of di-silylated derivative, bis(tert-butyldimethylsilyoxylethyl)sulfide (TDG-(TBDMS)2). Under the pretreatment conditions used, in which 0.5 ml of water sample supplemented with 100 microM potassium chloride was evaporated to dryness under reduced pressure, followed by reaction with N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide at 60 degrees C for 1 h, TDG-(TBDMS)2 was reproducibly detected with about a 55% recovery and a limit of detection (LOD, scan mode, S/N = 3) of 5.4 ng/ml. TDG was also determined by GC-MS from a 0.5 ml serum sample (after perchloric acid deproteinization) and from a 0.1 ml urine sample, after TBDMS derivatization. The LOD was determined to be 7.0 and 110 ng/ml for serum and urine, respectively. PMID:15641367

  8. The characterization of eight maceral concentrates by means of Curie point pyrolysis-gas chromatography and Curie point pyrolysis-gas chromatography-mass spectrometry

    Microsoft Academic Search

    Margriet Nip; J. W. de Leeuw; P. A. Schenck

    1988-01-01

    In order to study the relationships between the chemical structures of coals, coal macerals and their precursors (plant tissues), eight coal macerals originating from the Yorkshire coal basin (U.K.) were studied by Curie point pyrolysis-gas chromatography and Curie point pyrolysis-gas chromatography-mass spectrometry. The samples were selected on the basis of a previous study of a large set of macerals. The

  9. Simultaneous determination of lincomycin and spectinomycin residues in animal tissues by gas chromatography-nitrogen phosphorus detection and gas chromatography-mass spectrometry with accelerated solvent extraction

    Microsoft Academic Search

    Y. Tao; D. Chen; G. Yu; H. Yu; Y. Pan; Y. Wang; L. Huang; Z. Yuan

    2011-01-01

    A new multi-dimensional analytical method using gas chromatography-nitrogen phosphorus detection (GC-NPD) and gas chromatography-mass spectrometry (GC-MS) was developed for qualitative and quantitative measurement of lincomycin and spectinomycin residues in food animal tissues. This method is based on a new extraction procedure using accelerated solvent extraction (ASE). The analytes were extracted by phosphate buffer with trichloroacetic acid de-proteinisation and clean-up by

  10. Characterization of tetramethylammonium hydroxide thermochemolysis products of near-shore marine sediments using gas chromatography\\/mass spectrometry and gas chromatography\\/combustion\\/isotope ratio mass spectrometry

    Microsoft Academic Search

    Jerry Pulchan; Teofilo A. Abrajano; Robert Helleur

    1997-01-01

    The study describes the application of gas chromatography\\/mass spectrometry (GC\\/MS) and gas chromatography\\/combustion\\/isotope ratio mass spectrometry (GC\\/C\\/IRMS) to characterize the molecular and compound-specific stable carbon isotope composition, respectively, of tetramethylammonium hydroxide (TMAH) thermochemolysis products of organic matter present in marine sediments. The objective of the study was to examine the usefulness of TMAH thermochemolysis products in identifying organic markers of

  11. Identification and differentiation of benzodiazepines and their metabolites in urine by computerized gas chromatography-mass spectrometry.

    PubMed

    Maurer, H; Pfleger, K

    1987-11-27

    A method for the identification and differentiation of the following benzodiazepines and their metabolites in urine after acid hydrolysis and acetylation is described: bromazepam, camazepam, chlordiazepoxide, clobazam, clonazepam, clorazepate, clotiazepam, cloxazolam, delorazepam, diazepam, ethylloflazepate, flunitrazepam, flurazepam, halazepam, ketazolam, loprazolam, lorazepam, lormetazepam, medazepam, metaclazepam, midazolam, nitrazepam, nordazepam, oxazepam, oxazolam, prazepam, quazepam, temazepam and tetrazepam. The acetylated extract was analysed by computerized gas chromatography-mass spectrometry. An on-line computer allowed rapid detection using ion chromatography with ions m/z 205, 211, 230, 241, 245, 249, 312 and 333. The identity of positive signals in the reconstructed ion chromatogram was confirmed by a comparison of the stored full mass spectra with reference spectra. The ion chromatograms, reference mass spectra and gas chromatographic retention indices (on OV-101) are documented. PMID:3437028

  12. Quantitative determination of dimethyl fumarate in silica gel by solid-phase microextraction/gas chromatography/mass spectrometry and ultrasound-assisted extraction/gas chromatography/mass spectrometry.

    PubMed

    Bocchini, Paola; Pinelli, Francesca; Pozzi, Romina; Ghetti, Federica; Galletti, Guido C

    2015-06-01

    Dimethyl fumarate (DMF) is a chemical compound which has been added to silica gel bags used for preserving leather products during shipment. DMF has recently been singled out due to its ability to induce a number of medical problems in people which touch products contaminated by it. Its use as a biocide has been recently made illegal in Europe. Two different extraction techniques, namely ultrasound-assisted extraction (UAE) and solid-phase microextraction (SPME), both coupled with gas chromatography/mass spectrometry were applied to the quantitative determination of DMF in silica gel. Linearity of the methods, reproducibility and detection limits were determined. The two methods were applied to the quantification of DMF in thirty-four silica gel samples used as anti-mould agents in different leather products sold in Italy, and the obtained results were statistically compared. PMID:25939646

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

    PubMed

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

    2013-11-01

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

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

    PubMed

    Zhang, Xu; Yang, Lu; Mester, Zoltan

    2012-09-26

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

  15. Fourier transform-infrared spectroscopy and Gas chromatography-mass spectroscopy: Reliable techniques for analysis of Parthenium mediated vermicompost

    NASA Astrophysics Data System (ADS)

    Rajiv, P.; Rajeshwari, Sivaraj; Venckatesh, Rajendran

    2013-12-01

    Fourier transform infrared spectroscopy (FT-IR) and Gas chromatography-mass spectroscopy have been carried out to investigate the chemical composition of Parthenium mediated vermicompost. Four different concentrations of Parthenium and cow dung mixtures were vermicomposted using the earthworms (Eudrilus eugeniae). FT-IR spectra reveal the absence of Parthenin toxin (sesquiterpene lactone) and phenols in vermicompost which was obtained from high concentration of cow dung mixed treatments. GC-MS analysis shows no phenolic compounds and predominant level of intermediate metabolites such as 4,8,12,16-Tetramethylheptadecan-4-olide (7.61%), 2-Pentadecanone, 6,10,14-trimethyl- (5.29%) and Methyl 16-methyl-heptadecanoate (4.69%) during the vermicomposting process. Spectral results indicated that Parthenin toxin and phenols can be eradicated via vermicomposting if mixed with appropriate quantity of cow dung.

  16. Fourier transform-infrared spectroscopy and Gas chromatography-mass spectroscopy: reliable techniques for analysis of Parthenium mediated vermicompost.

    PubMed

    Rajiv, P; Rajeshwari, Sivaraj; Venckatesh, Rajendran

    2013-12-01

    Fourier transform infrared spectroscopy (FT-IR) and Gas chromatography-mass spectroscopy have been carried out to investigate the chemical composition of Parthenium mediated vermicompost. Four different concentrations of Parthenium and cow dung mixtures were vermicomposted using the earthworms (Eudrilus eugeniae). FT-IR spectra reveal the absence of Parthenin toxin (sesquiterpene lactone) and phenols in vermicompost which was obtained from high concentration of cow dung mixed treatments. GC-MS analysis shows no phenolic compounds and predominant level of intermediate metabolites such as 4,8,12,16-Tetramethylheptadecan-4-olide (7.61%), 2-Pentadecanone, 6,10,14-trimethyl- (5.29%) and Methyl 16-methyl-heptadecanoate (4.69%) during the vermicomposting process. Spectral results indicated that Parthenin toxin and phenols can be eradicated via vermicomposting if mixed with appropriate quantity of cow dung. PMID:23998948

  17. Simultaneous determination of alachlor, metolachlor, atrazine, and simazine in water and soil by isotope dilution gas chromatography/mass spectrometry.

    PubMed

    Huang, L Q

    1989-01-01

    A multiresidue method was developed for the simultaneous determination of low parts per billion (ppb) concentrations of the herbicides alachlor, metolachlor, atrazine, and simazine in water and soil using isotope dilution gas chromatography/mass spectrometry (GC/MS). Known amounts of 15N,13C-alachlor and 2H5-atrazine were added to each sample as internal standards. The samples were then prepared by a solid phase extraction with no further cleanup. A high resolution GC/low resolution MS system with data acquisition in selected ion monitoring mode was used to quantitate herbicides in the extract. The limit of detection was 0.05 ppb for water and 0.5 ppb for soil. Accuracy greater than 80% and precision better than 4% was demonstrated with spiked samples. PMID:2651394

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

    PubMed

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

    2009-07-01

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

  19. Identification of nonecdysteroid steroids in hemolymph of both male and female Astacus leptodactylus (Crustacea) by gas chromatography-mass spectrometry.

    PubMed

    Ollevier, F; De Clerck, D; Diederik, H; De Loof, A

    1986-02-01

    The O-pentafluorobenzyloxime (OPFB)-heptafluorobutyrylester (HFB) derivatives of hemolymph steroid extracts from both male and female Astacus leptodactylus were subjected to negative ion chemical ionization and capillary gas chromatography-mass spectrometry (NCI/GC-MS). Five nonecdysteroid steroids, namely pregnenolone, 17 alpha-hydroxypregnenolone, testosterone, cholesterol, and 6 beta-hydroxyprogesterone were identified. With selected ion monitoring (SIM), indications were found for the presence of four more steroids: androstenedione, 5 alpha-dihydrotestosterone, 11-ketotestosterone, and 11 beta-hydroxytestosterone. The presence of 6 beta-hydroxyprogesterone could only be demonstrated in the female hemolymph. With the technique used, dehydroepiandrosterone, progesterone, 17 alpha-hydroxyprogesterone, and estrogens could not be detected in male or female hemolymph extracts. PMID:2937682

  20. Determination of some volatile compounds in alcoholic beverage by headspace solid-phase microextraction gas chromatography - mass spectrometry

    NASA Astrophysics Data System (ADS)

    Schmutzer, G.; Avram, V.; Feher, I.; David, L.; Moldovan, Z.

    2012-02-01

    The volatile composition of alcoholic beverage was studied by headspace solid-phase microextraction (HSSPME) method and gas chromatography - mass spectrometry (GC-MS). Some volatile compounds, such as alcohols, esters, terpenes and other are mainly responsible for the flavor of fortified wines and their amounts specify the quality of the alcoholic beverages. From this perspective it is interesting to develop a rapid, selective and sensitive analytical method suitable for simultaneous quantification of the main molecules being responsible for the organoleptic characteristic of alcoholic beverages. Vermouth fortified drink was analyzed in order to characterize the volatile profile. Using the HS-SPME/GC-MS a number of twenty-six volatile compounds from a commercial market alcoholic beverage were identified. The most abundant compounds were m-thymol, o-thymol and eugenol, alongside of the ethyl ester compounds.

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

    PubMed

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

    2010-03-19

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

  2. Absence of sugars in electrophoretically purified cytochrome b5 demonstrated by combined gas chromatography-mass spectrometry

    PubMed Central

    1981-01-01

    The problem of determining small but significant amounts of carbohydrates, in purified proteins, has been studied using the membrane protein, cytochrome b5. A newly developed method that involves direct gas chromatography-mass spectrometry of sugars obtained by hydrolysis of proteins purified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE) allows the identification and determination of small amounts of carbohydrates (e.g., 20 micrograms of glycoprotein containing a minimum of 0.1% monosaccharide), even in the presence of relatively high amounts of impurities. Application of this method to cytochrome b5 fragments obtained by tryptic digestion from rat liver microsomes and purified by combined gel filtration and ion exchange chromatography, followed by SDS PAGE, has consistently yielded values below 0.07 mol of the individual sugars and aminosugars per mole cytochrome b5. It is concluded that cytochrome b5, at least its trypsin-released major amino- terminal fragment, is not constitutively glycosylated. PMID:7251667

  3. Identification of Flavor Components in Perfumes by Headspace Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Knupp, Gerd; Kusch, Peter; Neugebauer, Michael

    2002-01-01

    An experiment for identification of flavor components in Original Eau de Cologne by headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS) with electron impact ionization was developed. A new SPME fiber with a dual coating of divinylbenzene and Carboxen, each suspended in polydimethylsiloxane, was used. The compounds were identified by search of the NIST 98 MS Library or by comparison with pure standards. The experiment was developed for second-year chemistry students to learn the principles of analytical instrumentation (GC-MS) and sample preparation techniques (HS-SPME). The students are able to complete this experiment in a single four-hour laboratory session.

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

    PubMed

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

    2013-10-11

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

  5. Determination of off-flavor compounds, 2-methylisoborneol and geosmin, in salmon fillets using stir bar sorptive extraction–thermal desorption coupled with gas chromatography–mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A sensitive and solvent-less method for the determination of musty and earthy off-flavor compounds, 2-methylisoborneol (MIB) and geosmin (GSM), in salmon tissue was developed using stir bar sorptive extraction -thermal desorption coupled with gas chromatography -mass spectrometry (SBSE -TD -GCMS). M...

  6. Sublimation extraction coupled with gas chromatography-mass spectrometry: A new technique for future in situ analyses of purines and pyrimidines on Mars

    Microsoft Academic Search

    D. P. Glavin; H. J. Cleaves; A. Buch; M. Schubert; A. Aubrey; J. L. Bada; P. R. Mahaffy

    2006-01-01

    We have developed a sublimation technique coupled with chemical derivatization and gas chromatography mass spectrometry (GC-MS) to detect nucleobases and other volatile organic compounds derived from bacteria in Mars analog materials. To demonstrate this technique, a sample of serpentine inoculated with Escherichia coli (E. coli) cells was heated to 500°C for several seconds under Martian ambient pressure. The sublimate was

  7. In situ derivatization reaction and determination of ibuprofen in water samples using headspace generation-programmed temperature vaporization-gas chromatography-mass spectrometry

    Microsoft Academic Search

    José Luis Pérez Pavón; Ana María Casas Ferreira; María Esther Fernández Laespada; Bernardo Moreno Cordero

    2009-01-01

    The aim of the present work is to propose a method for the determination of ibuprofen, as a typical representative of pharmaceutical compounds, in aqueous samples. To do so, an in situ derivatization reaction in aqueous medium was employed in the vial of a headspace sampler (HS), after which instrumental measurements were made with gas chromatography-mass spectrometry (GC-MS). As the

  8. DETERMINATION OF A BOUND MUSK XYLENE METABOLITE IN CARP HEMOGLOBIN AS A BIOMARKER OF EXPOSURE BY GAS CHROMATOGRAPHY MASS SPECTROMETRY USING SELECTED ION MONITORING

    EPA Science Inventory

    Musk xylene (MX) is widely used as a fragrance ingredient in commercial toiletries. Identification and quantification of a bound 4-amino-MX (AMX) metabolite was carried out by gas chromatography-mass spectrometry (GC/MS), with selected ion monitoring (SIM). Detection of AMX occur...

  9. AUTOMATED GEL-PERMEATION SYSTEM FOR REMOVAL OF LIPIDS IN GAS CHROMATOGRAPHY/MASS SPECTROMETRIC ANALYSIS OF FATTY TISSUES FOR XENOBIOTIC CHEMICALS

    EPA Science Inventory

    The interference of natural lipids in gas chromatography/mass spectrometric analysis of xenobiotic chemicals in fatty tissue can be substantially reduced using gel-permeation chromatographic removal of the lipids. This paper presents an inexpensive controller which can be used wi...

  10. Detection of aldehydes in lung cancer cell culture by gas chromatography/mass spectrometry and solid-phase microextraction with on-fiber derivatization

    E-print Network

    Shan, Guangqing

    2007-09-17

    on the fiber. Finally, the aldehyde oximes formed on the fiber were analyzed by gas chromatography/mass spectrometry (GC/MS). Using this method, acetaldehyde decrease was found in both non-small lung cancer cell cultures studied compared to the medium control...

  11. Thermal Extraction?Two-Dimensional Gas Chromatography?Mass Spectrometry with Heart-Cutting for Nitrogen Heterocyclics in Biomass Burning Aerosols

    EPA Science Inventory

    A thermal extraction-two-dimensional gas chromatography-mass spectrometry (TE-GC-MS) method (with heart-cutting) is developed for quantitatively assessing nitrogen (N-bearing organic species (e.g., pyrrole, pyridine, nitriles, and amines) in aerosols emitted from agricultural fir...

  12. Solidphase extraction and gas chromatography–mass spectrometry determination of kaempferol and quercetin in human urine after consumption of Ginkgo biloba tablets

    Microsoft Academic Search

    D. G. Watson; E. J. Oliveira

    1999-01-01

    A method was developed for the quantification of the flavonoids quercetin and kaempferol in human urine using a solid-phase extraction procedure followed by gas chromatography–mass spectrometry. Deuterated internal standards of the analytes were spiked into the samples prior to extraction. The limit of detection of the method was ca. 10 pg on column and precision of the method for quantification

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

    PubMed Central

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

    1990-01-01

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

  14. [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

  15. 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

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

    PubMed

    Hilkert; Douthitt; Schlüter; Brand

    1999-07-01

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

  17. Nature of unresolved complex mixture in size-distributed emissions from residential wood combustion as measured by thermal desorption-gas chromatography-mass spectrometry

    Microsoft Academic Search

    Michael D. Hays; N. Dean Smith; Yuanji Dong

    2004-01-01

    Unresolved complex mixture (UCM) is an analytical artifact of gas chromatographs of combustion source-related fine aerosol extracts. In this study the UCM is examined in size-resolved fine aerosol emissions from residential wood combustion. The aerosols are sorted by size in an electrical low-pressure impactor (ELPI) and subsequently analyzed by thermal desorption\\/gas chromatography\\/mass spectrometry (TD\\/GC\\/MS). A semiquantitative system for predicting the

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

    Microsoft Academic Search

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

    1992-01-01

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

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

    Microsoft Academic Search

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

    2007-01-01

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

  20. SPECIATION OF SUBSURFACE CONTAMINANTS BY CONE PENETROMETRY GAS CHROMATOGRAPHY/MASS SPECTROMETRY. (R826184)

    EPA Science Inventory

    A thermal extraction cone penetrometry gas chroma tography/mass spectrometry system (TECP GC/MS) has been developed to detect subsurface contaminants in situ. The TECP can collect soil-bound organics up to depths of 30 m. In contrast to traditional cone penetrometer sample collec...

  1. High-resolution gas chromatography/mass spectrometric analysis of tobacco and marijuana sterols.

    PubMed

    Novotny, M; Lee, M L; Low, C E; Maskarinec, M P

    1976-05-01

    Components of the sterol fraction of tobacco and marijauna were resolved as trimethylsilyl derivatives by gas chromatography with glass capillary columns. Ten phytosterols in tobacco and five in marijuana were identified by comparisons of their retention with authentic compounds on three different stationary phases and through mass-spectral data. PMID:941185

  2. Method Development for the Determination of Fluorotelomer Alcohols in Soils by Gas Chromatography Mass Spectrometry

    EPA Science Inventory

    Fluorotelomer alcohols (FTOHs) have been widely studied as precursors to perfluorocarboxylates, e.g. 8:2 FTOH degrades to perfluorooctanoic acid (PFOA). This presentation describes an analytical method for the extraction and analysis of 6:2, 8:2, and 10:2 FTOHs. Gas chromatograph...

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

    Microsoft Academic Search

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

    2011-01-01

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

  4. Identification of steroidal hydrocarbons in refined confectionery fats by gas chromatography–mass spectrometry

    Microsoft Academic Search

    Colin Crews; Rosa Calvet-Sarret; Paul Brereton

    1999-01-01

    Steroidal hydrocarbon degradation products (steradienes) of sterols formed during the bleaching of confectionery fats were isolated by a new rapid silica column technique. The steradienes were separated by gas chromatography with mass spectrometric detection. Refined mango butter contained predominantly a sterene which was unrelated to the major desmethyl sterols. Dehydration products of triterpene alcohols were isolated from stearin fractions of

  5. Performance and optimization of a combustion interface for isotope ratio monitoring gas chromatography/mass spectrometry

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    Conditions and systems for on-line combustion of effluents from capillary gas chromatographic columns and for removal of water vapor from product streams were tested. Organic carbon in gas chromatographic peaks 15 s wide and containing up to 30 nanomoles of carbon was quantitatively converted to CO2 by tubular combustion reactors, 200 x 0.5 mm, packed with CuO or NiO. No auxiliary source of O2 was required because oxygen was supplied by metal oxides. Spontaneous degradation of CuO limited the life of CuO reactors at T > 850 degrees C. Since NiO does not spontaneously degrade, its use might be favored, but Ni-bound carbon phases form and lead to inaccurate isotopic results at T < 1050 degrees C if gas-phase O2 is not added. For all compounds tested except CH4, equivalent isotopic results are provided by CuO at 850 degrees C, NiO + O2 (gas-phase mole fraction, 10(-3)) at 1050 degrees C and NiO at 1150 degrees C. The combustion interface did not contribute additional analytical uncertainty, thus observed standard deviations of 13C/12C ratios were within a factor of 2 of shot-noise limits. For combustion and isotopic analyses of CH4, in which quantitative combustion required T approximately 950 degrees C, NiO-based systems are preferred, and precision is approximately 2 times lower than that observed for other analytes. Water must be removed from the gas stream transmitted to the mass spectrometer or else protonation of CO2 will lead to inaccuracy in isotopic analyses. Although thresholds for this effect vary between mass spectrometers, differential permeation of H2O through Nafion tubing was effective in both cases tested, but the required length of the Nafion membrane was 4 times greater for the more sensitive mass spectrometer.

  6. Performance and optimization of a combustion interface for isotope ratio monitoring gas chromatography/mass spectrometry.

    PubMed

    Merritt, D A; Freeman, K H; Ricci, M P; Studley, S A; Hayes, J M

    1995-07-15

    Conditions and systems for on-line combustion of effluents from capillary gas chromatographic columns and for removal of water vapor from product streams were tested. Organic carbon in gas chromatographic peaks 15 s wide and containing up to 30 nanomoles of carbon was quantitatively converted to CO2 by tubular combustion reactors, 200 x 0.5 mm, packed with CuO or NiO. No auxiliary source of O2 was required because oxygen was supplied by metal oxides. Spontaneous degradation of CuO limited the life of CuO reactors at T > 850 degrees C. Since NiO does not spontaneously degrade, its use might be favored, but Ni-bound carbon phases form and lead to inaccurate isotopic results at T < 1050 degrees C if gas-phase O2 is not added. For all compounds tested except CH4, equivalent isotopic results are provided by CuO at 850 degrees C, NiO + O2 (gas-phase mole fraction, 10(-3)) at 1050 degrees C and NiO at 1150 degrees C. The combustion interface did not contribute additional analytical uncertainty, thus observed standard deviations of 13C/12C ratios were within a factor of 2 of shot-noise limits. For combustion and isotopic analyses of CH4, in which quantitative combustion required T approximately 950 degrees C, NiO-based systems are preferred, and precision is approximately 2 times lower than that observed for other analytes. Water must be removed from the gas stream transmitted to the mass spectrometer or else protonation of CO2 will lead to inaccuracy in isotopic analyses. Although thresholds for this effect vary between mass spectrometers, differential permeation of H2O through Nafion tubing was effective in both cases tested, but the required length of the Nafion membrane was 4 times greater for the more sensitive mass spectrometer. PMID:11536720

  7. Determination of 3-quinuclidinyl benzilate (QNB) and its major metabolites in urine by isotope dilution gas chromatography/mass spectrometry.

    PubMed

    Byrd, G D; Paule, R C; Sander, L C; Sniegoski, L T; White, E; Bausum, H T

    1992-01-01

    In response to the scheduled destruction of U.S. military stockpiles of the hallucinogenic agent 3-quinuclidinyl benzilate (QNB), a specific confirmatory test for human exposure to QNB was developed. The amount of the parent compound in the urine as well as the two major metabolites, 3-quinuclidinol (Q) and benzilic acid (BA), was determined because the relationship between QNB dose and levels of QNB and its metabolites in human urine is not known. QNB was determined in urine samples spiked at a target level of 0.5 ng/mL, and the metabolites BA and Q were determined at a target level of 5 ng/mL. The method uses solid-phase extraction to isolate each analyte from the urine and isotope dilution gas chromatography/mass spectrometry for quantitation. Each analyte is converted to its trimethylsilyl derivative for analysis. The analytical method was tested on eight different urine samples spiked with known amounts of the analytes near the target levels, at 10 times the target levels, and blank (unspiked) urine samples. The variabilities in the method are for the most part evenly distributed between three imprecision categories: GC/MS measurement, sample preparation, and the urine samples. The total imprecision (1 standard deviation) of a single measurement is about 15% of the value for each analyte. PMID:1522714

  8. Global profiling of ultraviolet-induced metabolic disruption in Melissa officinalis by using gas chromatography-mass spectrometry.

    PubMed

    Kim, Sooah; Yun, Eun Ju; Hossain, Md Aktar; Lee, Hojoung; Kim, Kyoung Heon

    2012-08-01

    Melissa officinalis contains various secondary metabolites that have health benefits. Generally, irradiating plants with ultraviolet (UV)-B induces the accumulation of secondary metabolites in plants. To understand the effect of UV-B irradiation on the metabolism of M. officinalis, metabolomics based on gas chromatography-mass spectrometry (GC-MS) was used in this study. The GC-MS analysis revealed 37 identified metabolites from various chemical classes, including alcohols, amino acids, inorganic acids, organic acids, and sugars. The metabolite profiles of the groups of M. officinalis irradiated with UV-B were separated and differentiated according to their irradiation times (i.e., 0, 1, and 2 h), using principal component analysis (PCA) and hierarchical clustering analysis (HCA), respectively. The PCA score plots of PC1 and PC2 showed that the three groups with different irradiation times followed a certain trajectory with increasing UV-B irradiation. HCA revealed that metabolic patterns differed among the three groups, and the 1 h-irradiated group was more similar to the control group (0 h) than the 2 h-irradiated group. In particular, UV-B irradiation of plants led to a decrease in sugars such as fructose, galactose, sucrose, and trehalose and an increase in metabolites in the tricarboxylic acid cycle, the proline-linked pentose phosphate pathway, and the phenylpropanoid pathway. This study demonstrated that metabolite profiling with GC-MS is useful for gaining a holistic understanding of UV-induced changes in plant metabolism. PMID:22729379

  9. Development of a gas chromatography-mass spectrometry method for the quantification of glucaric Acid derivatives in beverage substrates.

    PubMed

    Craig, Ana Paula; Fields, Christine C; Simpson, John V

    2014-01-01

    A gas chromatography-mass spectrometry (GC-MS) method using the standard addition methodology was developed for the determination of glucuronolactone (GL) and glucuronic acid (DGuA) in four beverages categorized as detoxification, recovery, or energy drinks. The method features a precolumn derivatization step with a combination of BSTFA (N,O-bis(trimethylsilyl)trifluoroacetamide) and TMCS (trimethylchlorosilane) to silylate the analytes. The sample pretreatment required no extraction, filtration, or reduction step prior to the injection. The quantification of the analytes was performed using a five-point standard addition protocol. The proposed method presented excellent intraday precision (%RSD < 10) and linearity for GL calibration curves (correlation coefficients > 0.995) and acceptable linearity for DGuA calibration curves (correlation coefficients > 0.97). The estimated limits of detection (LOD) and quantification (LOQ) for GL ranged from 0.006?ppm to 0.14?ppm, and 0.02?ppm to 0.47?ppm, respectively. The estimated LOD and LOQ for DGuA determination ranged, respectively, from 0.06?ppm to 1.1?ppm and 0.2?ppm to 3.8?ppm. The results demonstrated that the method should be regarded as a reliable alternative to the simultaneous determination of GL and DGuA. PMID:25024704

  10. Detection of 3-nitrotyrosine in human platelets exposed to peroxynitrite by a new gas chromatography/mass spectrometry assay.

    PubMed

    Jiang, H; Balazy, M

    1998-01-01

    A new sensitive and specific assay was developed and applied for the quantitative determination of 3-nitrotyrosine in proteins of human platelets. 3-Nitrotyrosine was quantitatively converted into a new pentafluorobenzyl derivative in a single step and detected as an abundant carboxylate anion at m/z 595 using negative ion chemical ionization gas chromatography/mass spectrometry. The internal standard, [13C6]-3-nitrotyrosine, was prepared via a new and efficient method using nitronium borofluorate dissolved in hydrochloric acid. The assay showed excellent linearity and sensitivity. Intact human platelets contained 1.4+/-0.6 ng of 3-nitrotyrosine per milligram of protein. Peroxynitrite increased 3-nitrotyrosine levels 4- to 535-fold at the concentration range of 10 to 300 microM. Decomposed peroxynitrite was without the effect. Nitrogen dioxide (43 microM) was also a potent tyrosine nitrating molecule, increasing the levels of 3-nitrotyrosine 153-fold. HOCl (50 microM) in the presence of nitrite (50 microM) increased the 3-nitrotyrosine levels 3-fold. Exposure of platelets to nitric oxide, nitrite, thrombin, adenosine diphosphate, platelet activating factor, and arachidonic acid had no effect on platelet 3-nitrotyrosine levels. PMID:10100490

  11. [Development of a gas chromatography-mass spectrometry method for the metabolomic study of rice (Oryza sativa L.) grain].

    PubMed

    Zhou, Jia; Wang, Shuangyuan; Chang, Yuwei; Zhao, Yanni; Lu, Xin; Zhao, Chunxia; Xu, Guowang

    2012-10-01

    An analytical strategy for the metabolic profiling of rice grain was developed based on gas chromatography-mass spectrometry (GC-MS). For the purpose of obtaining abundant metabolite information, sample preparation step prior to instrumental analysis is necessary to be optimized. D-optimal experimental design was applied to optimize the extraction solvent. Four solvents, including water, methanol, isopropanol and acetonitrile, and their combinations were evaluated for the extraction efficiency using multivariate statistical analysis (partial least square regression). The count of resolved peaks and the sum of peak areas were taken as the evaluation indexes. Methanol/water (80:20, v/v) mixture was highly efficient for rice metabolites and was selected as the suitable solvent formulation. Then, the analytical characteristics of the method were measured. More than 90% of the metabolites had satisfactory precisions, reproducibilities and stabilities (relative standard deviations (RSDs) < 30%). Most of the detected metabolites (about 88.0% of total peak area) showed good linear responses. With the optimized analytical protocol, 315 metabolites were detected in rice and 86 of which were structurally identified by searching in the NIST 08/Wiley standard mass spectral library, covering carbohydrates, amino acids, organic acids, steroids and so on which showed a broad coverage of metabolite data. The established method is expected to be useful for the metabolomic studies of rice. PMID:23383493

  12. Multiplexed dual first-dimension comprehensive two-dimensional gas chromatography-mass spectrometry with contra-directional thermal modulation.

    PubMed

    Savareear, Benjamin; Jacobs, Matthew R; Shellie, Robert A

    2014-10-24

    A multiplexed dual-primary column comprehensive two-dimensional gas chromatography-mass spectrometry approach (2GC×GC-MS) is introduced. The approach splits injected samples into two first-dimension columns with different stationary phases, and recombines the two streams into one second-dimension column that terminates at a single detector. The approach produces two two-dimensional chromatograms for each injection, and is made possible by using a dual-stage modulator operated in contra-directional modulation mode. The dual two-dimensional chromatograms produced by this single detector system provide complementary information due to selectivity differences between the three separation columns used in the column ensemble. An aged Australian tea tree (Melaleuca alternifolia) essential oil was analyzed to demonstrate the 2GC×GC-MS approach. The number of compounds separated by each of the GC×GC separations in the 2GC×GC experiment is comparable to conventional GC×GC experiments with matching column configurations. Robust peak assignment was possible for this sample based on the combination of MS library matches and multiple linear retention index searching. Forty-nine components (22 unique) were identified using a non-polar×mid-polar column combination and 34 components (7 unique) were positively identified using a polar×mid-polar column combination. Twenty-seven peak assignments were corroborated by positive identification in both of the multiplexed separations. PMID:25249490

  13. 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

  14. Trace determination of bisphenol A and phytoestrogens in infant formula powders by gas chromatography-mass spectrometry.

    PubMed

    Kuo, Han-Wen; Ding, Wang-Hsien

    2004-02-20

    This investigation describes a reliable and sensitive method for simultaneously determining bisphenol A (BPA) and two major phytoestrogens, daidzein and genistein, in powdered milks and infant formulas by gas chromatography-mass spectrometric analysis after trimethylsilylation. To reduce the matrix interference associated with the constituents of the formulas, the dissolved formula solutions were firstly ultra-centrifuged and the analytes in the supernatant were then extracted using a C18 solid-phase extraction column. The accuracy and precision of the method were determined and the technique was successfully employed to measure trace concentrations of BPA, daidzein and genistein in powdered formulas. The results show that BPA, daidzein and genistein were detected in all the testing samples (n = 6) at concentrations from 45 to 113 ng/g (except one infant formula), 20 to 2050 ng/g and 21 to 6510 ng/g, respectively. The highest concentrations of daidzein and genistein (i.e., 2050 and 6510 ng/g) were detected in a soy-based powdered infant formula. The quantitation limits were 1.0 ng/g for BPA, and 10 ng/g for daidzein and genistein using 0.5 g powdered milk samples. PMID:14971485

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

    PubMed

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

    2007-11-15

    Headspace single drop microextraction coupled to gas chromatography-mass spectrometry yielded a simple, fast and virtually solventless analytical protocol used for the headspace analysis of aqueous samples contaminated with methylcyclopentadienyl-manganese tricarbonyl (MMT). Initially, several experimental parameters were controlled and optimized and the optimum conditions found were 2.5 microl octane microdrop exposed for 20 min to the headspace of a 10 ml aqueous sample (15 ml vial) containing 20% (w/v) NaCl and stirred at 1250 rpm. The calculated calibration curves gave a high level of linearity for MMT with correlation coefficients >0.9995 after conducting a 3-day study. The limit of detection was calculated to be 0.21 microg l(-1). The proposed method achieved an enrichment factor of the order of 2100 and a 53% recovery after extracting the spiked aqueous solution for 20 min under the optimized experimental conditions. The repeatability and intra-day reproducibility of the proposed method, expressed as relative standard deviation were 8.4 and 6.4%, respectively. Finally, analysis of spiked tap and wastewater samples revealed that matrix had little effect upon extraction. PMID:18371611

  16. Identification and Quantification of Several Contaminated Compounds in Replacement Liquids of Electronic Cigarettes by Gas Chromatography-Mass Spectrometry.

    PubMed

    Oh, Jin-Aa; Shin, Ho-Sang

    2015-07-01

    Electronic cigarettes (E-cigarettes) are devices that are refilled with replacement liquids, which normally contain propylene glycol, nicotine and the desired flavor blend. Many consumers suspect that hazardous substances are present in addition to nicotine content. In this study, eight contaminated compounds in 105 replacement liquids from 11 types of E-cigarettes sold in the Republic of Korea were identified and quantified by gas chromatography-mass spectrometry. Diethyl phthalate and diethylhexyl phthalate were detected in concentration ranges of 0.01-1745.20 mg/L (47.6% detection frequency) and 0.06-81.89 mg/L (79.1% detection frequency) in the replacement liquids. Triethylene glycol, tetraethylene glycol and pentaethylene glycol were quantified in concentration ranges of 0.1-19.3 mg/L (10.5% detection frequency), 0.1-30.1 mg/L (12.4% detection frequency) and 0.1-24.9 mg/L (6.7% detection frequency) in the same samples. cis-3-Hexene-1-ol, methyl cinnamate and dodecane were quantified in concentration ranges of 0.03-3267.46 mg/L (70.5% detection frequency), 4.41-637.54 mg/L (6.7% detection frequency) and 0.01-639.96 mg/L (47.6% detection frequency) in the samples. PMID:25404560

  17. Isotope dilution gas chromatography-mass spectrometry in the determination of benzene, toluene, styrene and acrylonitrile in mainstream cigarette smoke.

    PubMed

    Byrd, G D; Fowler, K W; Hicks, R D; Lovette, M E; Borgerding, M F

    1990-03-23

    A cryogenic trapping method with isotope dilution gas chromatography-mass spectrometry analysis has been developed for the determination of benzene, toluene, styrene and acrylonitrile in mainstream vapor phase cigarette smoke. The method is simple, direct, and quantitative. Vapor phase samples are collected cryogenically in a series of four traps following removal of the particulate phase with a Cambridge filter pad. For all four analytes, 75-85% of the total amounts recovered were found in the initial trap and less than 1% in the final trap. Assessment of instrumental precision by multiple injections of a sample gave relative standard deviations of less than 2%. Linear calibration for all analytes over the analysis range gave an r2 value greater than 0.99 with average relative standard deviations at the mean ranging from 1.4 to 8.2%. The cigarettes analyzed include a reference cigarette (Kentucky 1R4F), a commercial ultra-low "tar" mentholated cigarette, and two cigarettes that heat but do not burn tobacco. The values determined for the four analytes in the 1R4F samples are comparable to reported values of similar cigarettes. The cigarettes which heat rather than burn tobacco yield less of all four analytes compared to the other cigarettes in the study. PMID:2185256

  18. Assay of physiological levels of 2,3-butanediol diastereomers in blood and urine by gas chromatography-mass spectrometry.

    PubMed

    Montgomery, J A; Jetté, M; Brunengraber, H

    1990-02-15

    We present an assay for 2,3-butanediol by gas chromatography-mass spectrometry of its trimethylsilyl ethers. 2R,3R- and/or 2S,3S-2,3-butanediol and meso-2,3-butanediol are quantitated with corresponding internal standards of [2,3-2H2]butanediol. Limits of detection are 1 and 0.1 microM for split and splitless injections, respectively. Blood concentrations of 2,3-butanediol in nonalcoholics are 0.5 +/- 0.3 (SD) microM for 2R,3R- and/or 2S,3S-2,3-butanediol and 0.8 +/- 0.4 microM for meso-2,3-butanediol (n = 9). Two hours after alcohol ingestion, blood levels had risen in eight of nine subjects to 1.2 +/- 0.7 microM for 2R,3R-/2S,3S-2,3-butanediol and to 1.2 +/- 0.6 microM for meso-2,3-butanediol. Baseline urinary excretion of 2,3-butanediol is 0.4 +/- 0.2 mumol/mmol creatinine for 2R,3R-/2S,3S-2,3-butanediol and 0.9 +/- 0.5 mumol/mmol creatinine for meso-2,3-butanediol. PMID:2344048

  19. Characterization of organic fouling in reverse osmosis membranes by headspace solid phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Martínez, C; Gómez, V; Pocurull, E; Borrull, F

    2015-01-01

    Adsorption of organic substances on reverse osmosis (RO) membrane surfaces may form an organic film on the membrane, known as organic fouling, and cause flow-rate loss. This problem is mostly unavoidable as no pretreatment method exists for perfect removal of possible foulants, including organic compounds resulting from undesirable bioactivity. Understanding the characteristics of fouling layers is an essential step towards overall improvement of RO membrane operations. In this study, the organic fouling in RO membranes treating the effluent of a secondary treatment from an urban wastewater treatment plant was characterized. Headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry has been used for the first time, to provide valuable information of organic fouling. Different polarity SPME fibers were tested for this purpose. In addition, the characterization of the organic fouling obtained by HS-SPME was compared with the results obtained by extraction using several organic solvents. The results indicated that more compound families can be identified by HS-SPME than by organic solvent extraction. Moreover, complementary organic analyses were done for better understanding of the organic fouling in RO membranes, such as total organic carbon and loss on ignition. PMID:25607678

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

    PubMed

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

    2014-02-01

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

  1. Chemical characterization of automotive polyurethane foam using solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Parsons, Norah S; Lam, Michael H W; Hamilton, Sheilah E

    2013-01-01

    Solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was used in this study to identify volatile organic compounds (VOCs) emitted from heated automotive polyurethane (PU) foam collected from 17 different automobiles located in Yuen Long, HK SAR. The samples (0.05 g each) underwent incubation inside 5-mL glass vials for 30 min, and the VOCs were then collected from the headspace with a polydimethylsiloxane fiber by insertion for 30 min. The VOCs were then qualitatively identified by GC-MS analysis and were mostly found to be saturated hydrocarbons. However, differences were noted from car to car in the retention time range of 10-23 min. The VOCs collected during this segment of retention time from the PU foams ranged from antioxidants, food preservatives, pesticides, plasticizers, flame retardants to antiseptic agents. The results obtained from this study therefore highlight the usefulness of SPME/GC-MS as a form of chemical characterization in the analysis of PU foams in forensic casework. PMID:22994148

  2. Sensitive and rapid method to quantify icaritin and desmethylicaritin in human serum using gas chromatography-mass spectrometry.

    PubMed

    Shen, Ping; Wong, Shih Peng; Yong, E L

    2007-09-15

    The prenyl-flavones, icaritin and desmethylicaritin, are bioactive compounds from the traditional Chinese medicinal herb, Epimedium, extracts of which can enhance bone health in animal models. In order to examine their bioavailability in humans, we have developed and validated a sensitive method to quantify icaritin and desmethylicaritin in human sera, using gas chromatography-mass spectrometry. The serum samples were extracted with ethyl acetate and then derivatized with BSTFA in pyridine (4:1). With genistein as internal standard, calibration curves with good linearity (R(2)>0.99) within the concentration range of 0.15-10nM in the selective ion monitoring mode were obtained. The limits of detection and quantization were 11 and 33 pM for icaritin, and 23 and 70 pM for desmethylicaritin, respectively; inter- and intra-assay variabilities were <15%, and accuracies were between 89 and 110%. Icaritin, but not desmethylicaritin, was detected from 1h, increasing to a peak at 8h (1.51+/-1.6 nM) in sera of human volunteers after ingestion of an aqueous decoction of Epimedium. This sensitive method can be used to quantify serum levels of icaritin and desmethylicaritin for pharmacokinetic studies. PMID:17632044

  3. Microwave assisted extraction for the determination of ethyl glucuronide in urine by gas chromatography-mass spectrometry.

    PubMed

    Freire, Iván Alvarez; Barrera, Ana María Bermejo; Silva, Purificación Cid; Duque, María Jesús Tabernero; Gómez, Purificación Fernández; Eijo, Patricia López

    2008-08-01

    Alcohol is the most frequently abused 'addictive substance' that causes serious social problems throughout the world; thus alcoholism is of particular interest in clinical and forensic medicine. Ethyl glucuronide (EtG) is a marker of recent alcohol consumption that detects alcohol use reliably over a definite time period. The present paper describes a new method for the determination of EtG in urine. It was based both on microwave assisted extraction (MAE) to extract the analyte from urine samples, and gas chromatography-mass spectrometry (GC-MS) to identify and quantify the EtG in selected ion monitoring (SIM) mode. The method was applied to 33 urine samples from alcohol users, obtaining positive results in all cases. It was fully validated including a linear range (0.1-100 microg ml(-1)) and the main precision parameters. In summary, the use of microwave assisted extraction turned out to be a substantially simpler, faster and more sensitive procedure than any other conventional sample preparations. PMID:18344200

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

    PubMed

    España Amórtegui, Julio César; Guerrero Dallos, Jairo Arturo

    2015-09-01

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

  5. A gas chromatography-mass spectrometry based study on serum metabolomics in rats chronically poisoned with hydrogen sulfide.

    PubMed

    Deng, Mingjie; Zhang, Meiling; Huang, Xueli; Ma, Jianshe; Hu, Lufeng; Lin, Guanyang; Wang, Xianqin

    2015-05-01

    Hydrogen sulfide poisoning is a common occupational hazard, whose mortality and incidence rates are first and second, respectively, among occupational poisoning incidents in China. The main target organs of its toxicity are in the central nervous system and respiratory system. However, there are currently no specific direct tests that can be used to diagnose poisoned patients. In this study, we developed a serum metabonomic method using orthogonal partial least squares-discriminate analysis (OPLS-DA), based on gas chromatography-mass spectrometry (GC/MS) to evaluate the effect of chronic poisoning by hydrogen sulfide in rats. The OPLS-DA data demonstrated that the model group (n = 60) differed significantly from the control group (n = 30), suggesting that the metabolic profiles of the two groups are markedly different. Alterations in the levels of some metabolites such as citrate, galactose, lactate, mannose, inositol, urea, phosphate, alanine and valine were detected by OPLS-DA analysis. We observed changes in metabolic pathways including lipid metabolism, energy metabolism and amino metabolism in the model group. Our results indicate that GC/MS-based metabonomic methods may provide novel detection means for chronic hydrogen sulfide poisoning. PMID:25882152

  6. [Characterization of C5-C7 alkenes in gasoline from methanol to olefins process using gas chromatography-mass spectrometry].

    PubMed

    Li, Jiwen; Li, Wei; Wang, Chuan

    2013-11-01

    Gas chromatography-mass spectrometry (GC-MS) qualitative characterization of C5 -C7 alkenes in gasoline from methanol to olefins (MTO) was investigated in detail. It showed that the retention indices of 49 alkenes, 11 alkadienes and 9 cycloalkenes, a total of 69 C5-C7 isomeric alkenes were determined and qualitatively confirmed. The retention indices of all C5-C7 alkenes in MTO gasoline were measured on polydimethylsiloxane as the stationary phase. According to the library of retention indices by GC-MS characterization, the contents of C5-C7 alkenes in MTO gasoline were analyzed by GC and characterized by its composition of hydrocarbon categories. The results of quantitative analysis showed that the composition of MTO gasoline mainly consisted of C5-C7 alkenes, and a small amount of alkadienes and cycloalkenes. The contents of alkanes and cycloalkanes existed in MTO gasoline were very low. The study of the composition is helpful for the comprehensive application of MTO gasoline. PMID:24558852

  7. [Determination of short chain chlorinated paraffins in leather products by solid phase extraction coupled with gas chromatography-mass spectrometry].

    PubMed

    Zhang, Weiya; Wan, Xin; Li, Lixia; Wang, Chengyun; Jin, Shupei; Xing, Jun

    2014-10-01

    The short chain chlorinated paraffins (SCCPs) are the additives frequently used in the leather production in China, but they have been put into the list of forbidden chemicals issued by European Union recently. In fact, there is not a commonly recognized method for the determination of the SCCPs in the leather products due to the serious matrix interferences from the leather products and the complex chemical structures of the SCCPs. A method of solid phase extraction coupled with gas chromatography-mass spectrometry (SPE-GC-MS) was established for the determination of the SCCPs in the leather products after the optimization of the SPE conditions. It was found that the interferences from the leather products were thor- oughly separated from the analyte of the SCCPs on a home-made solid phase extraction (SPE) column filled with silica packing while eluted with a mixed solvent of n-hexane-methylene chloride (2:1, v/v). With this method, the recoveries for the SCCPs spiked in the real leather samples varied from 90.47% to 99.00% with the relative standard deviations (RSDs) less than 6.7%, and the limits of detection (LODs) were between 0.069 and 0.110 mg/kg. This method is suitable for qualitative and quantitative analysis of SCCPs in the leather products. PMID:25739278

  8. [Simultaneous determination of melamine and creatinine in milk and milk products by gas chromatography-mass spectrometry].

    PubMed

    Zeng, Kai; Liu, Zhirong; Ning, Yajun; Li, Jinlin; Tang, Jun; Zhang, Min

    2013-05-01

    A method established for determining melamine and creatinine in milk and milk products. The samples were extracted with 1% trichloracetic acid solution. The extract was cleaned-up by using a mixed-mode cation ion exchange SPE column and evaporated to dryness under nitrogen. The residue was derived by bis (trimethylsilyl) trifluoroacetamide-chlorotrimethylsilane (BSTFA-TMCS), then determined by gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode. Melamine and creatinine had good linearity in the range of 0.1 - 50 mg/L with the correlation coefficients higher than 0.99, and the limits of quantification were 0.10 mg/kg and 0.20 mg/kg, respectively. The recoveries of melamine and creatinine were 80.7% - 116.8% and 77.6% - 107.5% with RSD no more than 9.4% and 8.5% in the spiked range of 10 - 100 mg/kg and 0.1 - 5.0 mg/kg, respectively. The method is accurate, sensitive, and suitable for the determination of creatinine in milk and milk products. PMID:24010350

  9. 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

  10. [Determination of gomisin A (TJN-101) and its metabolite in rat serum by gas chromatography-mass spectrometry].

    PubMed

    Matsuzaki, Y; Ishibashi, E; Koguchi, S; Wakui, Y; Takeda, S; Aburada, M; Oyama, T

    1991-10-01

    Gomisin A (TJN-101) is one of the lignan components isolated from Schisandra Fruits. A high sensitive and precise method for the determination of TJN-101 and its major metabolite (Met. B) in the rat serum was developed by selected ion monitoring (SIM) with gas chromatography-mass spectrometry (GC/MS) using a fused silica capillary column (SPB-1, Supelco). A 100 microliter serum sample was used for the solid phase extraction. The calibration curves of TJN-101 and Met.B both showed a good linearity between 2.0 and 2000.0 ng/ml. The analytical precision (intra-assay, C.V. less than 4.7%), recoveries (98.4 +/- 10.1%), and detection limit (2 ng/ml) of TJN-101 indicated that this system was suited for the determination of TJN-101 in biological fluid. In case of Met.B, the same results as TJN-101, were obtained. After oral administration of TJN-101 at a dose of 10 mg/kg to male rats, the average values of the maximal serum concentration of TJN-101 and Met.B were 1446.1 +/- 131.8 and 317.4 +/- 18.5 ng/ml, respectively. The serum concentrations of these substances could be monitored sufficiently for 8 h after dosing. PMID:1812283

  11. 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

  12. Novel ethyl-derivatization approach for the determination of fluoride by headspace gas chromatography/mass spectrometry.

    PubMed

    Pagliano, Enea; Meija, Juris; Ding, Jianfu; Sturgeon, Ralph E; D'Ulivo, Alessandro; Mester, Zoltán

    2013-01-15

    We report a novel derivatization chemistry for determination of fluoride based on the batch reaction of fluoride ions with triethyloxonium tetrachloroferrate(III) in a closed vessel to yield fluoroethane. Gaseous fluoroethane was readily separated from the matrix, sampled from the headspace, and determined by gas chromatography/mass spectrometry. The method was validated using rainwater certified reference material (IRMM CA408) and subsequently applied to the determination of fluoride in various matrixes, including tap water, seawater, and urine. An instrumental limit of detection of 3.2 ?g/L with a linear range up to 50 mg/L was achieved. The proposed derivatization is a one-step reaction, requires no organic solvents, and is safe, as the derivatizing agent is nonvolatile. Determination of fluoride is affected by common fluoride-complexing agents, such as Al(III) and Fe(III). The effect of large amounts of these interferences was studied, and the adverse effect of these ions was eliminated by use of the method of standard additions. PMID:23215254

  13. MSPD procedure for determining buprofezin, tetradifon, vinclozolin, and bifenthrin residues in propolis by gas chromatography-mass spectrometry.

    PubMed

    dos Santos, Thaíse Fernanda Santana; Aquino, Adriano; Dórea, Haroldo Silveira; Navickiene, Sandro

    2008-03-01

    A simple and effective extraction method based on matrix solid-phase dispersion (MSPD) was developed to determine bifenthrin, buprofezin, tetradifon, and vinclozolin in propolis using gas chromatography-mass spectrometry in selected ion monitoring mode (GC-MS, SIM). Different method conditions were evaluated, for example type of solid phase (C(18), alumina, silica, and Florisil), the amount of solid phase and eluent (n-hexane, dichloromethane, dichloromethane-n-hexane (8:2 and 1:1, v/v) and dichloromethane-ethyl acetate (9:1, 8:2 and 7:3, v/v)). The best results were obtained using 0.5 g propolis, 1.0 g silica as dispersant sorbent, 1.0 g Florisil as clean-up sorbent, and dichloromethane-ethyl acetate (9:1, v/v) as eluting solvent. The method was validated by analysis of propolis samples fortified at different concentration levels (0.25 to 1.0 mg kg(-1)). Average recoveries (four replicates) ranged from 67% to 175% with relative standard deviation between 5.6% and 12.1%. Detection and quantification limits ranged from 0.05 to 0.10 mg kg(-1) and 0.15 to 0.25 mg kg(-1) propolis, respectively. PMID:18193409

  14. Development of gas chromatography/mass spectrometry following headspace solid-phase microextraction for fast determination of asarones in plasma.

    PubMed

    Deng, Chunhui; Lin, Shuang; Huang, Taoming; Duan, Gengli; Zhang, Xiangmin

    2006-01-01

    Asarones (alpha-asarone and beta-asarone) are the active components in the traditional Chinese medicine (TCM) of Acorus tatarinowii Schott, which has been used to treat epilepsy for several thousand years. To perform the pharmacokinetics (PK) study of alpha- and beta-asarone from the TCM essential oil, a simple, rapid and sensitive method was developed for the determination of asarones from the TCM in rabbit plasma, based on headspace solid-phase microextraction (HS-SPME) followed by gas chromatography/mass spectrometry (GC/MS) with electron ionization (EI). The extraction parameters of headspace volume, fiber coating, sample temperature, extraction time, stirring rate and ion strength were systemically optimized. Furthermore, the method linearity, detection limit and precision were also investigated. It was shown that the proposed method provided a good linearity (0.02-20 microg/mL, R(2) > 0.99), low detection limit (<2.0 ng/mL) and good precision (RSD < 7.0%). Finally, HS-SPME followed by GC/MS was applied to fast determination of alpha- and beta-asarone in rabbit plasma at different time points after oral adminstration of the essential oil from A. tatarinowii. The experimental results suggest that the proposed method provides an alternative approach to the PK studies of volatile compounds in TCMs. PMID:16773672

  15. Determination of aromatic hydrocarbons in bituminous emulsion sealants using headspace solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Tang, Bing; Isacsson, Ulf

    2006-12-22

    The possibility of quantitative determination of aromatic hydrocarbons in bituminous emulsion sealants was investigated using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS). The target analytes studied were benzene, toluene, ethylbenzene, p-, m-, and o-xylene (BTEX) as well as 1,3,5- and 1,2,4-trimethylbenzene. Experimental factors influencing HS-SPME efficiency were studied (sample-headspace equilibration time, extraction time and sample matrix effects). A HS-SPME method using surrogate matrix was developed. The detection limit was estimated as approximately 0.1 ppmw for the target analytes investigated. Good linearity was observed (R(2)>0.997) for all calibration curves obtained. The repeatability of the method (RSD, relative standard deviation) was found less than 10%. The accuracy of the method given by recovery of spiked samples was between 99 and 116%. The HS-SPME method developed was applied to two commercially available bituminous emulsion sealants. External calibration and standard addition approaches were investigated, and statistical paired t-test was performed. The contents of target aromatic hydrocarbons in the sealants studied varied from approximately 0.4 to 150 ppmw. The method developed shows potential as a tool for the determination of aromatic hydrocarbons in emulsified bituminous materials. PMID:17069821

  16. Investigation of used synthetic lubricants by computerized gas chromatography/mass spectrometry.

    PubMed

    Sturaro, A; Doretti, L; Parvoli, G

    1990-12-01

    The chemical fractions of a used, synthetic lubricating oil for petrol engines were separated by flash chromatography on a silica gel column using variable mixtures of hexane/chloroform as eluents. The products extracted in the most polar fraction were separated by gas chromatography and then analyzed by computerized mass spectrometry. The analytical method used allowed the identification, among the various compounds, of a family of tetrahydropyran homologues with an aminic chain, phthalates, thiophene and pyridine derivatives. The presence of these structures, some of which are of toxicological interest, was also shown by infrared spectra. PMID:2270471

  17. Spectral Deconvolution for Gas Chromatography Mass Spectrometry-Based Metabolomics: Current Status and Future Perspectives

    PubMed Central

    Du, Xiuxia; Zeisel, Steven H

    2013-01-01

    Mass spectrometry coupled to gas chromatography (GC-MS) has been widely applied in the field of metabolomics. Success of this application has benefited greatly from computational workflows that process the complex raw mass spectrometry data and extract the qualitative and quantitative information of metabolites. Among the computational algorithms within a workflow, deconvolution is critical since it reconstructs a pure mass spectrum for each component that the mass spectrometer observes. Based on the pure spectrum, the corresponding component can be eventually identified and quantified. Deconvolution is challenging due to the existence of co-elution. In this review, we focus on progress that has been made in the development of deconvolution algorithms and provide thoughts on future developments that will expand the application of GC-MS in metabolomics. PMID:24688694

  18. Quantitation of ethyl glucuronide in serum & urine by gas chromatography - mass spectrometry

    PubMed Central

    Sharma, Priyamvada; Bharat, Venkatesh; Murthy, Pratima

    2015-01-01

    Background & objectives: Alcohol misuse has now become a serious public health problem and early intervention is important in minimizing the harm. Biochemical markers of recent and high levels of alcohol consumption can play an important role in providing feedback regarding the health consequences of alcohol misuse. Existing markers are not sensitive to recent consumption and in detecting early relapse. Ethyl glucuronide (EtG), a phase-II metabolite of ethanol is a promising marker of recent alcohol use and can be detected in body fluids. In this study an analytical technique for quantitation of EtG in body fluids using solid-phase extraction (SPE) and gas chromatography (GC) with mass spectrometric detection (MS) was developed and validated. Methods: De-proteinization of serum and urine samples was done with perchloric acid and hydrochloric acid, respectively. Serum samples were passed through phospholipids removal cartridges for further clean up. EtG was isolated using amino propyl solid phase extraction columns. Chromatographic separation was achieved by gas chromatography with mass spectrometry. Results: Limit of detection and limit of quantitation were 50 and 150 ng/ml for urine and 80 and 210 ng/ml for serum, respectively. Signal to noise ratio was 3:1, mean absolute recovery was 80-85 per cent. Significant correlation was obtained between breath alcohol and serum EtG levels (r=0.853) and urine EtG and time since last abuse (r = -0.903) in clinical samples. Interpretation & conclusions: In the absence of other standardized techniques to quantitate EtG in biological samples, this GC-MS method was found to have high throughput and was sensitive and specific. PMID:25857498

  19. Full evaporation dynamic headspace and gas chromatography-mass spectrometry for uniform enrichment of odor compounds in aqueous samples.

    PubMed

    Ochiai, Nobuo; Sasamoto, Kikuo; Hoffmann, Andreas; Okanoya, Kazunori

    2012-06-01

    A method for analysis of a wide range of odor compounds in aqueous samples at sub-ng mL?¹ to ?g mL?¹ levels was developed by full evaporation dynamic headspace (FEDHS) and gas chromatography-mass spectrometry (GC-MS). Compared to conventional DHS and headspace solid phase microextraction (HS-SPME), FEDHS provides more uniform enrichment over the entire polarity range for odor compounds in aqueous samples. FEDHS at 80°C using 3 L of purge gas allows complete vaporization of 100 ?L of an aqueous sample, and trapping and drying it in an adsorbent packed tube, while providing high recoveries (85-103%) of the 18 model odor compounds (water solubility at 25°C: log0.54-5.65 mg L?¹, vapor pressure at 25°C: 0.011-3.2 mm Hg) and leaving most of the low volatile matrix behind. The FEDHS-GC-MS method showed good linearity (r²>0.9909) and high sensitivity (limit of detection: 0.21-5.2 ng mL?¹) for the model compounds even with the scan mode in the conventional MS. The feasibility and benefit of the method was demonstrated with analyses of key odor compounds including hydrophilic and less volatile characteristics in beverages (whiskey and green tea). In a single malt whiskey sample, phenolic compounds including vanillin could be determined in the range of 0.92-5.1 ?g mL?¹ (RSD<7.4%, n=6). For a Japanese green tea sample, 48 compounds including 19 potent odorants were positively identified from only 100 ?L of sample. Heat-induced artifact formation for potent odorants was also examined and the proposed method does not affect the additional formation of thermally generated compounds. Eighteen compounds including 12 potent odorants (e.g. coumarin, furaneol, indole, maltol, and pyrazine congeners) were determined in the range of 0.21-110 ng mL?¹ (RSD<10%, n=6). PMID:22542289

  20. 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.

  1. Identification of sildenafil, tadalafil and vardenafil by gas chromatography-mass spectrometry on short capillary column.

    PubMed

    Man, Che Nin; Nor, Noorjuliana Md; Lajis, Razak; Harn, Gam Lay

    2009-11-20

    Sildenafil and its analogues (tadalafil and vardenafil) are phosphodiesterase type 5 inhibitors used in the treatment of male erectile dysfunction. Some dietary supplements, herbal preparations and food products which claim to enhance male sexual function have been found to be adulterated with these drugs. In this study, a gas chromatograph-mass spectrometer (GC-MS) assay was developed for identification of the drugs. In addition to good and short chromatographic separation that can be achieved within 6 min by using a short 10 m capillary column, no prior sample clean-up before GC-MS analysis was required, thus making this assay a cost saving and rapid method. Furthermore, the assay is specific as the identification of sildenafil, tadalafil and vardenafil were done by detection of molecular ions; m/z 474, 389 and 488, [corrected] respectively, and several other characteristic ions resulted from the mass fragmentation of individual molecules. Using our currently developed assay, sildenafil and its analogues were successfully identified in food and herbal matrices. PMID:19853256

  2. [Determination of dioxins by gas chromatography-mass spectrometry coupled with large volume injection].

    PubMed

    Wang, Yawei; Zhang, Qinghua; Jiang, Guibin; He, Qing

    2007-01-01

    The common analytical instrument for dioxin analysis/determination is gas chromatograph (GC) coupled with an electron capture detector (ECD), a flame ionization detector (FID), and a mass spectrometer (MS) , etc. Generally, since the concentration levels in environmental samples are pg/g or pg/L, it requires a very high resolution and sensitivity for the analytical system. To solve the problem one way is to increase the amount of a sample, however, which can significantly increase the pretreatment work load. The other way is to increase the injection volume. In this paper, a method for dioxin determination was developed using GC-MS coupled with the large volume injection (LVI). Under the condition of maintaining the same amount of solute, the comparison was studied for the changes of peak areas and peak widths by the injection of different volumes from 1 to 100 microL. The results showed that the peak area and peak width did not have obvious changes, and the separation performance was not affected compared with the traditional split/splitless injection. The detection limits obtained are improved by 1 - 2 orders of magnitude over those using split/splitless injections. Once the operation conditions are optimized, LVI is more flexible in handling samples of wide concentration ranges than the traditional split/splitless inlet approach. PMID:17432569

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

    USGS Publications Warehouse

    Hladik, Michelle L.; McWayne, Megan M.

    2012-01-01

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

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

    PubMed

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

    2011-12-15

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

  5. Hydrocarbon phenotyping of algal species using pyrolysis-gas chromatography mass spectrometry

    PubMed Central

    2010-01-01

    Background Biofuels derived from algae biomass and algae lipids might reduce dependence on fossil fuels. Existing analytical techniques need to facilitate rapid characterization of algal species by phenotyping hydrocarbon-related constituents. Results In this study, we compared the hydrocarbon rich algae Botryococcus braunii against the photoautotrophic model algae Chlamydomonas reinhardtii using pyrolysis-gas chromatography quadrupole mass spectrometry (pyGC-MS). Sequences of up to 48 dried samples can be analyzed using pyGC-MS in an automated manner without any sample preparation. Chromatograms of 30-min run times are sufficient to profile pyrolysis products from C8 to C40 carbon chain length. The freely available software tools AMDIS and SpectConnect enables straightforward data processing. In Botryococcus samples, we identified fatty acids, vitamins, sterols and fatty acid esters and several long chain hydrocarbons. The algae species C. reinhardtii, B. braunii race A and B. braunii race B were readily discriminated using their hydrocarbon phenotypes. Substructure annotation and spectral clustering yielded network graphs of similar components for visual overviews of abundant and minor constituents. Conclusion Pyrolysis-GC-MS facilitates large scale screening of hydrocarbon phenotypes for comparisons of strain differences in algae or impact of altered growth and nutrient conditions. PMID:20492649

  6. Determination of glycols in biological specimens by gas chromatography-mass spectrometry.

    PubMed

    Gembus, Vincent; Goullé, Jean-Pierre; Lacroix, Christian

    2002-01-01

    A simple extraction and derivatization procedure for the analysis of eight glycols (ethylene glycol, EG; diethylene glycol, DEG; triethylene glycol, TEG; 1,2-propanediol, 1,2-PD; 1,3-propanediol, 1,3-PD; 1,2-butanediol, 1,2-BD; 2,3-butanediol, 2,3-BD; and hexylene glycol, HXG) using a 2-microL serum or blood sample is described. Following deproteinisation with acetonitrile, derivatization to its mono or di TMS derivative, glycols were detected using gas chromatography-electron impact mass spectrometry equipped with a split-spitless inlet and a DB-5MS column in the scan mode from 40 to 500 amu. Gamma-hydroxybutyrate-d6 (GHB-d6) was used as the internal standard. The limits of detection and quantitation in 2 pL of serum ranged, respectively, from 0.7 mg/L for EG to 8.5 mg/L for TEG and from 1.3 mg/L for EG to 18.2 mg/L for 1,2-PD. A linear response was observed over the concentration range from 1 to 800 mg/L for EG and 18 from 800 for TEG and 1,2-PD for serum and blood. Coefficients of variation for both intra-assay precision and interassay reproductibility ranged respectively between 1.9% for TEG to 4.9% for 1,2-PD (11.8% for HXG) and 3.5% for DEG to 9% for 2,3-BD (20.4 for HXG) at the 400 mg/L serum level. The method was applied to plasma and whole blood. PMID:12166815

  7. An empirical Bayes model using a competition score for metabolite identification in gas chromatography mass spectrometry

    PubMed Central

    2011-01-01

    Background Mass spectrometry (MS) based metabolite profiling has been increasingly popular for scientific and biomedical studies, primarily due to recent technological development such as comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GCxGC/TOF-MS). Nevertheless, the identifications of metabolites from complex samples are subject to errors. Statistical/computational approaches to improve the accuracy of the identifications and false positive estimate are in great need. We propose an empirical Bayes model which accounts for a competing score in addition to the similarity score to tackle this problem. The competition score characterizes the propensity of a candidate metabolite of being matched to some spectrum based on the metabolite's similarity score with other spectra in the library searched against. The competition score allows the model to properly assess the evidence on the presence/absence status of a metabolite based on whether or not the metabolite is matched to some sample spectrum. Results With a mixture of metabolite standards, we demonstrated that our method has better identification accuracy than other four existing methods. Moreover, our method has reliable false discovery rate estimate. We also applied our method to the data collected from the plasma of a rat and identified some metabolites from the plasma under the control of false discovery rate. Conclusions We developed an empirical Bayes model for metabolite identification and validated the method through a mixture of metabolite standards and rat plasma. The results show that our hierarchical model improves identification accuracy as compared with methods that do not structurally model the involved variables. The improvement in identification accuracy is likely to facilitate downstream analysis such as peak alignment and biomarker identification. Raw data and result matrices can be found at http://www.biostat.iupui.edu/~ChangyuShen/index.htm Trial Registration 2123938128573429 PMID:21985394

  8. Onsite well screening with a transportable gas chromatography/mass spectrometer system

    SciTech Connect

    Rossabi, J. [Westinghouse Savannah River Co., Aiken, SC (United States); Eckenrode, B.A.; Owens, B. [Viking Instruments Corp., Reston, VA (United States)

    1992-10-15

    The number of hazardous waste site operations continue to multiply. The requirements for efficient chemical assessment and monitoring of these sites become more stringent daily. As more samples are required, the time required for cleanup operations also increases and may make analytical costs prohibitive. Thus improvements in operation efficiency and reduction of cost in evaluating specific sites to minimize or eliminate their toxic effects on the surrounding environment are critical. For many years a formal policy did not exist for the disposal of waste solvents and other chemicals, thus many of these compounds were disposed of ensite. So long as these materials were contained onsite they were not considered to pose a threat to the surrounding environment. We have since determined that many of these compounds found their way into the groundwater. Contaminants such as trichloroethylene and perchloroethylene, which were heavily used for cleaning and degreasing purposes, must be monitored. Groundwater wells can be used to define the location and extent of the migration of any contaminant plume and aid in the determination of required cleanup. The major problem is that monitoring of hundreds of wells may be necessary, requiring several hundred samples on a quarterly basis to characterize the degree and extent of any contamination. Onsite analysis of monitoring wells for this characterization of waste operations could provide time savings and significant cost reduction. Field analyses can provide the required analytical results quickly and at a reduced cost without compromising either sample integrity or data quality. By using onsite analytical instrumentation, such as a field-transportable gas chromatograph/mass spectrometer (GC/MS), screening analyses can be performed to eliminate retturning to the laboratory with meaningless samples. Onsite GC/MS will provide qualitative or semi-quantitative information that can significantly simplify subsequent laboratory analyses.

  9. Organic compounds present in the natural Amazonian aerosol: Characterization by gas chromatography-mass spectrometry

    NASA Astrophysics Data System (ADS)

    Graham, Bim; Guyon, Pascal; Taylor, Philip E.; Artaxo, Paulo; Maenhaut, Willy; Glovsky, M. Michael; Flagan, Richard C.; Andreae, Meinrat O.

    2003-12-01

    As part of the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA)-Cooperative LBA Airborne Regional Experiment (CLAIRE) 2001 campaign in July 2001, separate day and nighttime aerosol samples were collected at a ground-based site in Amazonia, Brazil, in order to examine the composition and temporal variability of the natural "background" aerosol. We used a high-volume sampler to separate the aerosol into fine (aerodynamic diameter, AD < 2.5 ?m) and coarse (AD > 2.5 ?m) size fractions and quantified a range of organic compounds in methanolic extracts of the samples by a gas chromatographic-mass spectrometric technique. The carbon fraction of the compounds could account for an average of 7% of the organic carbon (OC) in both the fine and coarse aerosol fractions. We observed the highest concentrations of sugars, sugar alcohols, and fatty acids in the coarse aerosol samples, which suggests that these compounds are associated with primary biological aerosol particles (PBAP) observed in the forest atmosphere. Of these, trehalose, mannitol, arabitol, and the fatty acids were found to be more prevalent at night, coinciding with a nocturnal increase in PBAP in the 2-10 ?m size range (predominantly yeasts and other small fungal spores). In contrast, glucose, fructose, and sucrose showed persistently higher daytime concentrations, coinciding with a daytime increase in large fungal spores, fern spores, pollen grains, and, to a lesser extent, plant fragments (generally >20 ?m in diameter), probably driven by lowered relative humidity and enhanced wind speeds/convective activity during the day. For the fine aerosol samples a series of dicarboxylic and hydroxyacids were detected with persistently higher daytime concentrations, suggesting that photochemical production of a secondary organic aerosol from biogenic volatile organic compounds may have made a significant contribution to the fine aerosol. Anhydrosugars (levoglucosan, mannosan, galactosan), which are specific tracers for biomass burning, were detected only at low levels in the fine aerosol samples. On the basis of the levoglucosan-to-OC emission ratio measured for biomass burning aerosol, we estimate that an average of ˜16% of the OC in the fine aerosol was due to biomass burning during CLAIRE 2001, indicating that the major fraction was associated with biogenic particles.

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

    Microsoft Academic Search

    Hans Ragnar Norli; Agnethe Christiansen; Børge Holen

    2010-01-01

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

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

    Microsoft Academic Search

    Pierre Faure; Laurent Jeanneau; Frederic Lannuzel

    2006-01-01

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

  12. Assessment of Antifungal Drug Therapy in Autism by Measurement of Suspected Microbial Metabolites in Urine with Gas Chromatography-Mass Spectrometry

    Microsoft Academic Search

    William Shaw; Ellen Kassen; Enrique Chaves

    Context-Certain compounds found by gas chromatography-mass spectrometry in urine samples of children with autism might be produced by yeast in the gastrointestinal tract. Therefore, treatment with antifungal drugs might reduce clinical symptoms of autism. Objective-To determine if symptoms of autism and chemical compounds in urine samples of children with autism decreased after antifungal treatment. Design-A number of urinary organic acids

  13. Development of a headspace solid-phase microextraction\\/gas chromatography–mass spectrometry method for determination of organophosphorus pesticide residues in cow milk

    Microsoft Academic Search

    Frederico de M. Rodrigues; Paulo R. R. Mesquita; Lidia S. de Oliveira; Fabio S. de Oliveira; Adalberto Menezes Filho; Pedro. A. de P. Pereira; Jailson B. de Andrade

    2011-01-01

    In the past few years, organophosphorus compounds become one of the most widely used classes of pesticides due to their acute toxicity against a wide variety of pests. In this work, a method based on solid-phase microextraction in mode headspace (HS-SPME) coupled to gas chromatography–mass spectrometry (GC–MS) was developed and optimized through multivariate factorial design to determine residues of organophosphorus

  14. Characterization of Rhus vernicifera and Rhus succedanea lacquer films and their pyrolysis mechanisms studied using two-stage pyrolysis-gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    Noriyasu Niimura; Tetsuo Miyakoshi; Jun Onodera; Tetsuo Higuchi

    1996-01-01

    Rhus vernicifera and Rhus succedanea lacquers, which are used as a surface coating for wood, porcelain and metalware in Japan, were investigated using two-stage pyrolysis gas chromatography\\/mass spectrometry (Py-GC\\/MS). Urushiol and laccol components were detected in each lacquer film by pyrolysis at 400 °C. These are the monomers, and are characteristic of Rhus vernicifera and Rhus succedanea lacquer films. In

  15. Characterisation of lake-aquatic humic matter isolated with two different sorbing solid techniques: tetramethylammonium hydroxide treatment and pyrolysis-gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    Tero Lehtonen; Juhani Peuravuori; Kalevi Pihlaja

    2000-01-01

    Tetramethylammonium hydroxide (TMAH) treatment followed up with pyrolysis-gas chromatography\\/mass spectrometry (Py-GC\\/MS) was applied to characterise the structural composition of lake aquatic humic matter (HM). The HM samples were isolated with two different chromatographic methods: (1) non-ionic sorbing solid (standard XAD technique) with preacidification of a water sample to pH 2; and (2) weakly basic anion exchanger (DEAE, diethylaminoethyl cellulose) without

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

    Microsoft Academic Search

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

    2006-01-01

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

  17. Use of pyrolysis-gas chromatography\\/mass spectrometry to characterise binding media and protectives from a Coronelli’s terrestrial globe

    Microsoft Academic Search

    G. Chiavari; D. Fabbri; G. C. Galletti; S. Prati; N. Scianna

    2006-01-01

    During one of Coronelli's terrestrial globes restoration, belonging to the Bologna University, we found some substances considered not to be original. Their presence was both on the globe surface and under one of the gores. In order to characterise the organic material (original or added in restoring procedures) we employed pyrolysis-gas chromatography\\/mass spectrometry (Py-GC\\/MS). The analytical results reveal the presence

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

    Microsoft Academic Search

    W. Jira; K. Ziegenhals; K. Speer

    2008-01-01

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

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

    Microsoft Academic Search

    Mehdi Jalali-Heravi; Behrooz Zekavat; Hassan Sereshti

    2007-01-01

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

  20. Identification of natural dyes used in works of art by pyrolysis–gas chromatography\\/mass spectrometry combined with in situ trimethylsilylation

    Microsoft Academic Search

    María José Casas-Catalán; María Teresa Doménech-Carbó

    2005-01-01

    Samples of four natural dyes from different organic families—natural madder (anthraquinonoid), curcuma (curcuminoid), saffron (carotenoid) and indigo (indigotic)—were analysed using a new procedure based on pyrolysis–gas chromatography\\/mass spectrometry (Py–GC\\/MS), which includes the on-line derivatisation of the natural dyes using hexamethyldisilazane (HMDS). In addition, a previous procedure involving the addition of a 10% H2SO4 aqueous solution to the dye and further

  1. Application of solid-phase microextraction combined with gas chromatography–mass spectrometry to the determination of butylated hydroxytoluene in bottled drinking water

    Microsoft Academic Search

    Norma B Tombesi; Hugo Freije

    2002-01-01

    Butylated hydroxytoluene (BHT) is an antioxidant utilized as additive in foods and packaging plastic. Its presence in drinking water is possible if it is used as an antioxidant in the packaging plastic because it may migrate into the package’s contents. A method for the determination of BHT in water by means of solid-phase microextraction and gas chromatography–mass spectrometry has been

  2. Quantitative determination of some volatile suspected allergens in cosmetic creams spread on skin by direct contact sorptive tape extraction–gas chromatography–mass spectrometry

    Microsoft Academic Search

    B. Sgorbini; M. R. Ruosi; C. Cordero; E. Liberto; P. Rubiolo; C. Bicchi

    2010-01-01

    This study describes a method based on direct contact sorptive tape extraction followed by on-line thermal desorption gas chromatography–mass spectrometry (DC-STE–GC–MS) to detect and quantify a group of suspected volatile allergens on the European Union (E.U.) list and a related compound on the skin (the stratum corneum) of volunteers treated with a cream of known composition fortified with the reference

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

    Microsoft Academic Search

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

    2007-01-01

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

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

    Microsoft Academic Search

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

    2003-01-01

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

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

    Microsoft Academic Search

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

    2009-01-01

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

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

    Microsoft Academic Search

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

    2004-01-01

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

  7. 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.

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

    Microsoft Academic Search

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

    2008-01-01

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

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

    Microsoft Academic Search

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

    2006-01-01

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

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

    Microsoft Academic Search

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

    2003-01-01

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

  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 J.; Smith, Steven G.

    2014-01-01

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

  12. Combined solid-phase extraction and gas chromatography-mass spectrometry used for determination of chloropropanols in water.

    PubMed

    González, Paula; Racamonde, Inés; Carro, Antonia M; Lorenzo, Rosa A

    2011-10-01

    A sensitive and rapid derivatization method for the simultaneous determination of 1,3-dichloro-2-propanol (1,3-DCP) and 3-chloropropane-1,2-diol (3-MCPD) in water samples has been developed. The aim was to research the optimal conditions of the derivatization process for two selected reagents. A central composite design was used to determine the influence of derivatization time, derivatization temperature and reagent volume. A global desirability function was applied for multi-response optimization. The analysis was performed by gas chromatography-mass spectrometry. During the optimization of the extraction procedure, four different types of solid-phase extraction (SPE) columns were tested. It was demonstrated that the Oasis HLB cartridge produced the best recoveries of the target analytes. The pH value and the salinity were investigated using a Doehlert design. The best results for the SPE of both analytes were obtained with 1.5 g of NaCl and pH 6. The proposed method provides high sensitivity, good linearity (R(2)?0.999) and repeatability (relative standard deviations % between 2.9 and 3.4%). Limits of detection and quantification were in the range of 1.4-11.2 ng/mL and 4.8-34.5 ng/mL, respectively. Recoveries obtained for water samples were ca. 100% for 1,3-DCP and 3-MCPD. The method has been successfully applied to the analysis of different samples including commercially bottled water, an influent and effluent sewage. PMID:21818849

  13. Rapid determination of spore chemistry using thermochemolysis gas chromatography-mass spectrometry and micro-Fourier transform infrared spectroscopy.

    PubMed

    Watson, Jonathan S; Sephton, Mark A; Sephton, Sarah V; Self, Stephen; Fraser, Wesley T; Lomax, Barry H; Gilmour, Iain; Wellman, Charles H; Beerling, David J

    2007-06-01

    Spore chemistry is at the centre of investigations aimed at producing a proxy record of harmful ultraviolet radiation (UV-B) through time. A biochemical proxy is essential owing to an absence of long-term (century or more) instrumental records. Spore cell material contains UV-B absorbing compounds that appear to be synthesised in variable amounts dependent on the ambient UV-B flux. To facilitate these investigations we have developed a rapid method for detecting variations in spore chemistry using combined thermochemolysis gas chromatography-mass spectrometry and micro-Fourier transform infrared spectroscopy. Our method was tested using spores obtained from five populations of the tropical lycopsid Lycopodium cernuum growing across an altitudinal gradient (650-1981 m a.s.l.) in S.E. Asia with the assumption that they experienced a range of UV-B radiation doses. Thermochemolysis and subsequent pyrolysis liberated UV-B pigments (ferulic and para-coumaric acid) from the spores. All of the aromatic compounds liberated from spores by thermochemolysis and pyrolysis were active in UV-B protection. The various functional groups associated with UV-B protecting pigments were rapidly detected by micro-FTIR and included the aromatic C[double bond, length as m-dash]C absorption band which was exclusive to the pigments. We show increases in micro-FTIR aromatic absorption (1510 cm(-1)) with altitude that may reflect a chemical response to higher UV-B flux. Our results indicate that rapid chemical analyses of historical spore samples could provide a record ideally suited to investigations of a proxy for stratospheric O3 layer variability and UV-B flux over historical (century to millennia) timescales. PMID:17549272

  14. Determination of nitrogen mustard hydrolysis products, ethanolamines by gas chromatography-mass spectrometry after tert-butyldimethylsilyl derivatization.

    PubMed

    Ohsawa, Isaac; Seto, Yasuo

    2006-07-28

    A method for determining N-ethyldiethanolamine (EDEA), N-methyldiethanolamine (MDEA) and triethanolamine (TEA), hydrolysis products of nitrogen mustards, in water, urine and blood samples using gas chromatography-mass spectrometry (GC-MS) after derivatization by tert-butyldimethylsilylation (TBDMS) is described. The sample solution was evaporated to dryness, and reacted with N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) at 60 degrees C for 1h. The TBDMS derivatives were separated on a DB-5 column and detected by electron-ionization MS. The quantitation of EDEA, MDEA and TEA was performed by measuring the respective peak areas on the extracted ion chromatograms of m/z 216, m/z 202 and m/z 346, respectively, using nonadecane (C19), the peak area of which was measured at m/z 268, as an internal standard. When the water sample was initially analyzed, considerable loss of EDEA, MDEA and TEA occurred by evaporation. The addition of hydrochloric acid (HCl) to the water sample (final 1 mM), however, permitted quantitative recoveries to be achieved (88%, 88% and 79% for EDEA-(TBDMS)2, MDEA-(TBDMS)2 and TEA-(TBDMS)3, respectively). The limits of detections (LODs, scan mode, S/N = 3) were 2.5, 2.5 and 10 ng/ml for EDEA, MDEA and TEA, respectively. Ethanolamines could be also determined in urine samples (volume 0.1 ml), with reasonable recoveries of 72-100% by the addition of HCl (final 1 mM). For the analysis of serum samples, the sample was precipitated by the addition of perchloric acid (final 3.2%), and the resulting supernatant was neutralized with potassium carbonate, and then acidified by the addition of HCl. The recovery of TBDMS derivatives of ethanolamines was found to rather low (7-31%). PMID:16707130

  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. [Determination of 10 sedative-hypnotics in human plasma using pulse splitless injection technique and gas chromatography-mass spectrometry].

    PubMed

    Chang, Qing; Ma, Hongying; Wang, Fangjie; Ou, Honglian; Zou, Ming

    2011-11-01

    A simple, precise and sensitive gas chromatography-mass spectrometry (GC-MS) method coupled with pulse splitless injection technique was developed for the determination of 10 sedative-hypnotics (barbital, amobarbital, phenobarbital, oxazepam, diazepam, nitrazepam, clonazepam, estazolam, alprazolam, triazolam) in human plasma. The drugs spiked in plasma were extracted with ethyl acetate after alkalization with 0.1 mol/L NaOH solution. The organic solvent was evaporated under nitrogen stream, and the residues were redissolved by ethyl acetate. The separation was performed on an HP-5MS column (30 m x 250 microm x 0.25 microm). The analytes were determined and identified using selected ion monitoring (SIM) mode and scan mode, respectively. The internal standard method was used for the determination. The target analytes were well separated from each other on their SIM chromatograms and also on the total ion current (TIC) chromatograms. The blank extract from human plasma gave no peaks that interfered with all the analytes on the chromatogram. The calibration curves for 10 sedative-hypnotics showed excellent linearity. The correlation coefficients of all the drugs were higher than 0.9954. The recoveries of the drugs spiked in human plasma ranged from 92.28% to 111.7%, and the relative standard deviations (RSDs) of intra-day and inter-day determinations were from 4.09% to 14.26%. The detection limits ranged from 2 to 20 microg/L. The method is simple, reliable, rapid and sensitive for the determination and the quantification of 10 sedative-hypnotics in human plasma and seems to be useful in the practice of clinical toxicological cases. PMID:22393695

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

    PubMed

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

    2013-04-10

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

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

    SciTech Connect

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

    2010-04-15

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

  19. Serum level of 19-hydroxyandrostenedione during pregnancy and at delivery determined by gas chromatography/mass spectrometry

    SciTech Connect

    Osawa, Y.; Ohnishi, S.; Yarborough, C.; Ohigashi, S.; Kosaki, T.; Hashino, M.; Yanaihara, T.; Nakayama, T. (Medical Foundation of Buffalo Research Institute, NY (USA))

    1990-04-01

    19-Hydroxyandrostenedione (19-OHA) is secreted from the adrenal glands in men and women and also from the placenta during pregnancy. It has been found to cause hypertension in animal models. We have synthesized (7,7-2H2)-19-OHA with high deuterium content and, together with (7,7-2H2)A and (9,11-2H2)estrone (E1), have developed a quantitative assay of serum level 19-OHA, A, and E1 using the gas chromatography/mass spectrometry-mass fragmentography method to monitor individual subjects throughout pregnancy. The labeled 19-OHA, used as internal standard, showed only 6.73% of unlabeled compound. Recovery of standard 19-OHA, A, and E1 (5,000 pg each) added to male plasma was 97.4 +/- 2.3%, 96.3 +/- 2.1%, and 100.1 +/- 4.1% (mean +/- SD), respectively; the intraassay coefficient of variation was 2.1%, 3.5%, and 3.8%, respectively. Ten pregnant subjects without complications and 10 pregnant subjects near term with hypertension were selected (with informed consent). The 19-OHA and E1 serum concentrations of maternal venous blood from uncomplicated pregnancies increased significantly as gestation progressed (19-OHA: first trimester, 225 +/- 72; second trimester, 656 +/- 325; third trimester, 1,518 +/- 544 pg/ml), reaching the highest level at delivery (19-OHA: 1,735 +/- 684 pg/ml). Whereas a positive correlation was found between the level of 19-OHA and E1, no apparent change of the A level was observed during pregnancy. Levels of the three steroid hormones in pregnancy complicated by hypertension in the second and third trimester were not found to be significantly different from those of normal pregnancy (19-OHA of hypertensive subjects: second trimester, 762 +/- 349; third trimester, 1,473 +/- 491 pg/ml).

  20. Structural elucidation of chemical constituents from Benincasa hispida seeds and Carissa congesta roots by gas chromatography: Mass spectroscopy

    PubMed Central

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

    2015-01-01

    Background: Benincasa hispida (BH) and Carissa congesta (CC) are regarded as ethnopharmacological imperative plants in Asian countries. Objective: Phytochemical screening of the extracts has shown the presence of steroids, flavonoids, saponins, glycosides, tannins, phenolic compounds, fixed oils, and fats in the BH and CC extracts. The presence of lupeol has been reported previously by us using high-performance thin-layer chromatography and high-performance liquid chromatography. Materials and Methods: Present research studies encompasses identification of chemical constituents in BH seeds and CC roots petroleum ether extracts by hyphenated technique such as gas chromatography-mass spectroscopy (MS) which when coupled gives a clear insight of constituents. Results: The components were identified by matching mass spectra with MS libraries. There were 13 and 10 different compounds analyzed from CC and BH, respectively. The components present were Pentanoic acid, 5-hydroxy, 2,4-butylphenyl; n-Hexadecanoic acid (Palmitic acid); Sulfurous acid, 2-ethylhexylhepatdecyl ester; n-Tridecane; 6-methyltridecane; (9E, 12E)-9,12-Octadecadienyl chloride, Hexadecanoic acid, 3-(trimethylsilyl)-oxy] propyl ester; 9,12-Octadecadenoic acid, 2 hydroxy-1-(hyroxymethylethyl) ester; 9,12-Octadecadienoic acid, 2,3 dihydroxypropyl ester; n-Propyl-9,12-Octadecadienoate, Lupeol; Taraxasterol; 6a, 14a-Methanopicene, perhydro-12,4a, 61a, 9,9,12a-hepatmethyl-10-hydoxy and 9-Octadecene; 2-Isoprpenyl-5-methyl-6-hepten-1-ol; n-Hexadecanoic acid, 2-hyroxy-1-(hydroxymethyl) ethyl ether; Butyl-9,12-Octadecadieonate; Friedoolean-8-en-3-one; friedours-7-en-3-one; 13,27-Cyclosuran-3-one; Stigmaste-7,25-dien-3-ol (3?, 5?); Stigmasta-7,16-dien-3-ol; chrondrillasterol in BH seeds and CC roots extracts respectively. Conclusion: Eluted components from the extracts could provide further researchers to work with various pharmacological activities related models and studies. PMID:26130941

  1. Determination of alkylamines in atmospheric aerosol particles: a comparison of gas chromatography-mass spectrometry and ion chromatography approaches

    NASA Astrophysics Data System (ADS)

    Huang, R.-J.; Li, W.-B.; Wang, Y.-R.; Wang, Q. Y.; Jia, W. T.; Ho, K.-F.; Cao, J. J.; Wang, G. H.; Chen, X.; Haddad, I. EI; Zhuang, Z. X.; Wang, X. R.; Prévôt, A. S. H.; O'Dowd, C. D.; Hoffmann, T.

    2014-07-01

    In recent years low molecular weight alkylamines have been recognized to play an important role in particle formation and growth in the lower atmosphere. However, major uncertainties are associated with their atmospheric processes, sources and sinks, mostly due to the lack of ambient measurements and the difficulties in accurate quantification of alkylamines at trace level. In this study, we present the evaluation and optimization of two analytical approaches, i.e., gas chromatography-mass spectrometry (GC-MS) and ion chromatography (IC), for the determination of alkylamines in aerosol particles. Alkylamines were converted to carbamates through derivatization with isobutyl chloroformate for GC-MS determination. A set of parameters affecting the analytical performances of the GC-MS approach, including reagent amount, reaction time and pH value, was evaluated and optimized. The accuracy is 84.3-99.1%, and the limits of detection obtained are 1.8-3.9 pg (or 0.02-0.04 ng m-3). For the IC approach, a solid-phase extraction (SPE) column was used to separate alkylamines from interfering cations before IC analysis. 1-2% (v/v) of acetone (or 2-4% (v/v) of acetonitrile) was added to the eluent to improve the separation of alkylamines on the IC column. The limits of detection obtained are 2.1-15.9 ng (or 0.9-6.4 ng m-3), and the accuracy is 55.1-103.4%. The lower accuracy can be attributed to evaporation losses of amines during the sample concentration procedure. Measurements of ambient aerosol particle samples collected in Hong Kong show that the GC-MS approach is superior to the IC approach for the quantification of primary and secondary alkylamines due to its lower detection limits and higher accuracy.

  2. Cerumen of Australian stingless bees ( Tetragonula carbonaria): gas chromatography-mass spectrometry fingerprints and potential anti-inflammatory properties

    NASA Astrophysics Data System (ADS)

    Massaro, Flavia Carmelina; Brooks, Peter Richard; Wallace, Helen Margaret; Russell, Fraser Donald

    2011-04-01

    Cerumen, or propolis, is a mixture of plant resins enriched with bee secretions. In Australia, stingless bees are important pollinators that use cerumen for nest construction and possibly for colony's health. While extensive research attests to the therapeutic properties of honeybee ( Apis mellifera) propolis, the biological and medicinal properties of Australian stingless bee cerumen are largely unknown. In this study, the chemical and biological properties of polar extracts of cerumen from Tetragonula carbonaria in South East Queensland, Australia were investigated using gas chromatography-mass spectrometry (GC-MS) analyses and in vitro 5-lipoxygenase (5-LOX) cell-free assays. Extracts were tested against comparative (commercial tincture of A. mellifera propolis) and positive controls (Trolox and gallic acid). Distinct GC-MS fingerprints of a mixed diterpenic profile typical of native bee cerumen were obtained with pimaric acid (6.31 ± 0.97%, w/w), isopimaric acid (12.23 ± 3.03%, w/w), and gallic acid (5.79 ± 0.81%, w/w) tentatively identified as useful chemical markers. Characteristic flavonoids and prenylated phenolics found in honeybee propolis were absent. Cerumen extracts from T. carbonaria inhibited activity of 5-LOX, an enzyme known to catalyse production of proinflammatory mediators (IC50 19.97 ± 2.67 ?g/ml, mean ± SEM, n = 4). Extracts had similar potency to Trolox (IC50 12.78 ± 1.82 ?g/ml), but were less potent than honeybee propolis (IC50 5.90 ± 0.62 ?g/ml) or gallic acid (IC50 5.62 ± 0.35 ?g/ml, P < 0.001). These findings warrant further investigation of the ecological and medicinal properties of this stingless bee cerumen, which may herald a commercial potential for the Australian beekeeping industry.

  3. Determination of aromatic hydrocarbons in asphalt release agents using headspace solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Tang, Bing; Isacsson, Ulf

    2005-04-01

    The possibility of quantitative analysis of aromatic hydrocarbons in oil-based asphalt release agents was investigated using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS). The target analytes studied were benzene, toluene, ethylbenzene, p-, m-, and o-xylene (BTEX) and 1,3,5-trimethylbenzene and 1,2,4-trimethylbenzene. Experimental parameters influencing HS-SPME efficiency were studied (equilibration time between sample and headspace and between headspace and SPME fiber, sample amount and sample matrice effects). A HS-SPME method using hexadecane as a surrogate matrice was developed. The detection limit was estimated as 0.03-0.08 ppm (w/w) for the target analytes investigated. Good linearity was observed (R2 > 0.999) for all calibration curves at high, medium and low concentration level. The repeatability of the method (RSD, relative standard deviation) was found to be less than 10% (generally less than 5%) in triplicate samples and approximately 2% at eight consecutive tests on one and the same sample. The accuracy of the method given by recovery of spiked samples was between 85 and 106% (generally between 95 and 105%). The HS-SPME method developed was applied to four commercially available asphalt release agents. External calibration and standard addition approaches were investigated regarding accuracy. The results showed that standard addition generates higher accuracy than external calibration. The contents of target aromatic hydrocarbons in the asphalt release agents studied varied greatly from approximately 0.1-700 ppm. The method described looks promising, and could be a valuable tool for determination of aromatic hydrocarbons in different types of organic matrices. PMID:15830950

  4. Measurement of very low stable isotope enrichments by gas chromatography/mass spectrometry: application to measurement of muscle protein synthesis.

    PubMed

    Patterson, B W; Zhang, X J; Chen, Y; Klein, S; Wolfe, R R

    1997-08-01

    Measurement of muscle protein synthesis using stable isotopically labeled tracers usually requires isotope ratio mass spectrometry (IRMS) because of the need to measure very low enrichments of stable isotopically labeled tracers (tracer to tracee ratio [TTR], 0.005% to 0.10%). This approach is laborious, requiring purification of the metabolite of interest and combustion to a gas for IRMS analysis, and is best suited for use with 13C tracers. We have developed an approach whereby low enrichments can be conveniently measured by a conventional gas chromatography/mass spectrometry (GC/MS) instrument. The approach includes three critical elements: (1) use of a highly substituted tracer containing three or more labeled atoms, to measure enrichment above a very low natural abundance of highly substituted isotopomers; (2) use of a highly substituted natural abundance isotopomer as a base ion for comparison rather than the most abundant m + 0 isotopomer, to reduce the dynamic range of the isotopomer ratio measurement; and (3) a sensitive mass spectrometric analysis that measures the natural abundance of the isotopomer used as a tracer with a high signal to noise ratio (> 100:1). This approach was used to measure the rate of synthesis of muscle protein following a primed continuous infusion of L-[13C6]-phenylalanine (PHE) in eight fasted dogs and L-[2H3]-leucine in five fasted human subjects. Values for [13C6]-PHE enrichment by GC/MS rates were virtually identical to those obtained by a conventional approach using high-performance liquid chromatography (HPLC) to isolate PHE, combustion to CO2, and measurement of 13CO2 enrichment by IRMS (IRMS enrichment = 0.9988 x GC/MS enrichment, R2 = .891), resulting in identical values for muscle fractional synthesis rates ([FSRs] mean +/- SEM: 2.7 +/- 0.2 and 2.5 +/- 0.2%/d for GC/MS and IRMS, respectively). Human muscle synthesis rates measured by GC/MS analysis of [2H3]-leucine enrichment (1.90 +/- 0.17%/d) were similar to published values based on IRMS analysis using a 1- 13C-leucine tracer. We conclude that compared with the IRMS approach, the GC/MS approach offers faster throughput, has a lower sample requirement, and is suitable for a wider variety of tracers such as 2H. The principles outlined here should be applicable to the measurement of low enrichments by GC/MS in a wide variety of stable isotope tracer applications. PMID:9258279

  5. [Feasibility investigation of hydrogen instead of helium as carrier gas in the determination of five organophosphorus pesticides by gas chromatography-mass spectrometry].

    PubMed

    Liu, Zhenxue; Zhou, Shixue

    2015-01-01

    Helium is almost the only choosable carrier gas used in gas chromatography-mass spectrometry (GC-MS). A mixed standard solution of five organophosphorus pesticides was analyzed by using GC-MS, and hydrogen or helium as carrier gas, so as to study the feasibility of hydrogen instead of helium as carrier gas for the determination of organophosphorus pesticides. Combining a mass spectrum database built by ourselves, the results were deconvolved and identified by Automated Mass Spectral Deconvolution & Identification System (AMDIS32), a software belonging to the workstation of the instrument. Then, the statistical software, IBM SPSS Statistics 19.0 was used for the clustering analysis of the data. The results indicated that when hydrogen was used as carrier gas, the peaks of the pesticides detected were slightly earlier than those when helium used as carrier gas, but the resolutions of the chromatographic peaks were lower, and the fraction good indices (Frac. Good) were lower, too. When hydrogen was used as carrier gas, the signals of the pesticides were unstable, the measuring accuracies of the pesticides were reduced too, and even more, some compounds were undetectable. Therefore, considering the measuring accuracy, the signal stability, and the safety, etc., hydrogen should be cautiously used as carrier gas in the determination of organophosphorus pesticides by GC-MS. PMID:25958668

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

    PubMed

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

    2015-03-01

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

  7. Facts about the artifacts in the measurement of oxidative DNA base damage by gas chromatography-mass spectrometry.

    PubMed

    Dizdaroglu, M

    1998-12-01

    Recently, several papers reported an artifactual formation of a number of modified bases from intact DNA bases during derivatization of DNA hydrolysates to be analyzed by gas chromatography-mass spectrometry (GC/MS). These reports dealt with 8-hydroxyguanine (8-OH-Gua), 5-hydroxycytosine (5-OH-Cyt), 8-hydroxyadenine (8-OH-Ade), 5-hydroxymethyluracil (5-OHMeUra) and 5-formyluracil that represent only a small percentage of the 20 or so modified DNA bases that can be analyzed by GC/MS. Removal of intact DNA bases by prepurification of calf thymus DNA hydrolysates using HPLC was shown to prevent artifactual formation of these modified bases during derivatization. It needs to be emphasized that the procedures for hydrolysis of DNA and derivatization of DNA hydrolysates used in these papers substantially differed from the established procedures previously described. Furthermore, a large number of relevant papers reporting the levels of these modified bases in DNA of various sources have been ignored. Interestingly, the levels of modified bases reported in the literature were not as high as those reported prior to prepurification. Most values for the level of 5-OH-Cyt were even lower than the level measured after prepurification. Levels of 8-OH-Ade were quite close to, or even the same as, or smaller than the level reported after prepurification. The same holds true for 5-OHMeUra and 8-OH-Gua. All these facts raise the question of the validity of the claims about the measurement of these modified DNA bases by GC/MS. A recent paper reported a complete destruction of 2, 6-diamino-4-hydroxy-5-formamidopyrimidine (Fapy-Gua) and 4,6-diamino-5-formamidopyrimidine (FapyAde) by formic acid under the conditions of DNA hydrolysis prior to GC/MS. The complete destruction of FapyGua and FapyAde by formic acid is in disagreement with the data on these compounds in the literature. These two compounds were measured by GC/MS following formic acid hydrolysis for many years in our laboratory and by other researchers with no difficulties. These facts clearly raise the question of the validity of the claims made about the previous measurements of these compounds by GC/MS. PMID:10098459

  8. Solid-phase microextraction/gas chromatography-mass spectrometry method optimization for characterization of surface adsorption forces of nanoparticles.

    PubMed

    Omanovic-Miklicanin, Enisa; Valzacchi, Sandro; Simoneau, Catherine; Gilliland, Douglas; Rossi, Francois

    2014-10-01

    A complete characterization of the different physico-chemical properties of nanoparticles (NPs) is necessary for the evaluation of their impact on health and environment. Among these properties, the surface characterization of the nanomaterial is the least developed and in many cases limited to the measurement of surface composition and zetapotential. The biological surface adsorption index approach (BSAI) for characterization of surface adsorption properties of NPs has recently been introduced (Xia et al. Nat Nanotechnol 5:671-675, 2010; Xia et al. ACS Nano 5(11):9074-9081, 2011). The BSAI approach offers in principle the possibility to characterize the different interaction forces exerted between a NP's surface and an organic--and by extension biological--entity. The present work further develops the BSAI approach and optimizes a solid-phase microextraction gas chromatography-mass spectrometry (SPME/GC-MS) method which, as an outcome, gives a better-defined quantification of the adsorption properties on NPs. We investigated the various aspects of the SPME/GC-MS method, including kinetics of adsorption of probe compounds on SPME fiber, kinetic of adsorption of probe compounds on NP's surface, and optimization of NP's concentration. The optimized conditions were then tested on 33 probe compounds and on Au NPs (15 nm) and SiO2 NPs (50 nm). The procedure allowed the identification of three compounds adsorbed by silica NPs and nine compounds by Au NPs, with equilibrium times which varied between 30 min and 12 h. Adsorption coefficients of 4.66?±?0.23 and 4.44?±?0.26 were calculated for 1-methylnaphtalene and biphenyl, compared to literature values of 4.89 and 5.18, respectively. The results demonstrated that the detailed optimization of the SPME/GC-MS method under various conditions is a critical factor and a prerequisite to the application of the BSAI approach as a tool to characterize surface adsorption properties of NPs and therefore to draw any further conclusions on their potential impact on health. PMID:25168112

  9. A new reliable sample preparation for high throughput focused steroid profiling by gas chromatography-mass spectrometry.

    PubMed

    Anizan, Sébastien; Bichon, Emmanuelle; Monteau, Fabrice; Cesbron, Nora; Antignac, Jean-Philippe; Le Bizec, Bruno

    2010-10-22

    The use of steroid hormones as growth promoters in cattle has been banned within the European Union since 1988 but can still be fraudulently employed in animal breeding farms for anabolic purposes. If an efficient monitoring of synthetic compounds (screening and confirmation) is ensured today by many laboratories, pointing out suspicious samples from a natural steroids abuse remains a tricky challenge due to the difficulty to set relevant threshold levels for these endogenous compounds. The development of focused profiling or untargeted metabolomic approaches is then emerging in this context, with the objective to reveal potential biomarkers signing an exogenous administration of such natural steroids. This study aimed to assess sample preparation procedures based on microextraction and adapt them to high throughput urinary profiling or metabolomic analyses based on gas chromatography-mass spectrometry measurement. Two techniques have been tested and optimised, namely solid phase microextraction (SPME) and microextraction by packed sorbent (MEPS), using five model steroid metabolites (16?-hydroxyandrosterone, 2?-hydroxytestosterone, 11-keto,5?-androstanedione, 6?-hydroxyestradiol and 7?-hydroxypregnenolone). The considered performance criteria included not only the absolute response of the targeted compounds but also the robustness of the materials, and the global aspect of the diagnostic ion chromatograms obtained. After only five successive urinary extractions, a clear degradation of the SPME fiber was observed which led to discard this method as a relevant technique for profiling, whereas no degradation was observed on MEPS sorbent. Repeatability and recovery yields were calculated from urine samples fortified at 500 ?g L?¹ and extracted by MEPS. They were found respectively below 11% and above 60% for all model compounds. Detection limits were in the 5-15 ?g L?¹ range depending on the compounds, and a good linearity was observed on the 10-75 ?g L?¹ range (R² > 0.99). This methodology was applied on urine samples collected from control versus androstenedione-treated bovines, revealing a significant concentration increase for several well-known metabolites such as etiocholanolone, 5?-androstane-3?,17?-diol, 5?-androstane-3?,17?-diol and 5-androstene-3?,17?-diol. Finally, these results allowed to confirm the suitability of the developed strategy and give to this new MEPS application a promising interest in the field of GC-MS based steroid profiling and metabolomic. PMID:20537338

  10. 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.

  11. Determination of the chemical composition of titan4s aerosols analogues using pyrolysis gas chromatography mass spectrometry

    NASA Astrophysics Data System (ADS)

    He, J.; Buch, A.; Szopa, C.; Carrasco, N.

    2013-12-01

    The in situ chemical characterization of Titan's aerosols with the ACP-GCMS (Aerosol Collector and Pyrolyze-Gas Chromatograph and Mass Spectrometer) experiments onboard the Cassini-Huygens mission showed that the aerosols heated at 600°C were releasing two main gaseous compounds: NH3 and HCN. To better understand the process of production of these species at high temperature, and their relationship to the solid aerosol composition, it is possible to mimic in laboratory the Titan's atmosphere chemistry to produce analogues of Titan's aerosols (tholins), chemical and physical properties of which can be studied with laboratory instrumentation. In the present work, we studied the thermal decomposition of tholins produced with the PAMPRE cold plasma experiment[1]. For this study, pyrolysis at various temperatures, coupled to gas chromatography mass spectrometry (Pyr-GCMS), has been used in order to understand the origin and formation mechanism of the NH3 and HCN compounds. With this aim, two samples were produced using different initial CH4/N2 gaseous mixtures with different concentration ratios: (5:95) and (10:90). Pyr-GCMS was applied to characterize their chemical composition and molecule structure. In order to study the evolution of chemical compounds released as a function of temperature, the final pyrolysis temperature has been set from 100°C to 900°C with a 100°C step increment. The results show that the major compounds released are similar for the two different studied samples. They include hydrocarbon compounds, nitriles, ammonia, hydrogen cyanide, and some pyrrole isomers. Moreover, whatever the final temperature is, acetonitrile is the most abundant compound released by the samples. At 100°C only water contribution can be detected. Then the number of compounds released increases with the temperature up to 600°C. With the temperature increase the nature of the gaseous species detected does not change significantly. Pyrrole was not detected until the temperature exceeds 600°C for (5:95) sample and 400°C for (10:90) sample. Benzene has also been detected at 800°C for the (5:95) sample and 700°C for (10:90) sample. In the same way, toluene has been detected for the (10:90) sample at 700°C but it has not been detected for the (5:95) sample. This could indicate that carbon percentage is directly related to the benzene and toluene production. HCN and NH3 as the major compounds detected in the ACP instrument were also found in our results. It confirms that the aerosol analogues produced in PAMPRE set-up are among the most similar to Titan's aerosols, as found in [2]. [1] C. Szopa, G. Cernogora, L. Boufendi, et al. : PAMPRE: A dusty plasma experiment for Titan's tholins production and study, Planetary and Space Science, vol. 54, no. 4, pp. 394-404, 2006. [2] P. Coll, R. Navarro-González, C. Szopa, et al. : Can laboratory tholins mimic the chemistry producing Titan's aerosols? A review in light of ACP experimental results, Planetary and Space Science, vol. 77, pp. 91-103, 2013.

  12. Chapter 3. Determination of semivolatile organic compounds and polycyclic aromatic hydrocarbons in solids by gas chromatography/mass spectrometry

    USGS Publications Warehouse

    Zaugg, Steven D.; Burkhardt, Mark R.; Burbank, Teresa L.; Olson, Mary C.; Iverson, Jana L.; Schroeder, Michael P.

    2006-01-01

    A method for the determination of 38 polycyclic aromatic hydrocarbons (PAHs) and semivolatile organic compounds in solid samples is described. Samples are extracted using a pressurized solvent extraction system. The compounds of interest are extracted from the solid sample twice at 13,800 kilopascals; first at 120 degrees Celsius using a water/isopropyl alcohol mixture (50:50, volume-to-volume ratio), and then the sample is extracted at 200 degrees Celsius using a water/isopropyl alcohol mixture (80:20, volume-to-volume ratio). The compounds are isolated using disposable solid-phase extraction (SPE) cartridges containing divinylbenzene-vinylpyrrolidone copolymer resin. The cartridges are dried with nitrogen gas, and then sorbed compounds are eluted from the SPE material using a dichloromethane/diethyl ether mixture (80:20, volume-to-volume ratio) and passed through a sodium sulfate/Florisil SPE cartridge to remove residual water and to further clean up the extract. The concentrated extract is solvent exchanged into ethyl acetate and the solvent volume reduced to 0.5 milliliter. Internal standard compounds are added prior to analysis by capillary-column gas chromatography/mass spectrometry. Comparisons of PAH data for 28 sediment samples extracted by Soxhlet and the accelerated solvent extraction (ASE) method described in this report produced similar results. Extraction of PAH compounds from standard reference material using this method also compared favorably with Soxhlet extraction. The recoveries of PAHs less than molecular weight 202 (pyrene or fluoranthene) are higher by up to 20 percent using this ASE method, whereas the recoveries of PAHs greater than or equal to molecular weight 202 are equivalent. This ASE method of sample extraction of solids has advantages over conventional Soxhlet extraction by increasing automation of the extraction process, reducing extraction time, and using less solvent. Extract cleanup also is greatly simplified because SPE replaces commonly used gel permeation chromatography. The performance of the method (as expressed by mean recoveries and mean precision) was determined using Ottawa sand, a commercially available topsoil, and an environmental stream sediment, fortified at 1.5 and 15 micrograms per compound. Recoveries of PAH and semivolatile compounds in Ottawa sand samples fortified at 1.5 micrograms averaged 88 percent ? 9.4 percent relative standard deviation, and calculated initial method detection limits per compound averaged 14 micrograms per kilogram, assuming a 25-gram sample size. The recovery for 1,2,4-trichlorobenzene is less than 60 percent; thus, the concentration of this compound will always be reported as estimated with the E remark code. The analysis of 25 alkylated PAH homolog groups also can be determined with this method with extra data analysis and review, but because of the lack of authentic reference standard compounds, these results are considered to be semiquantitative. The PAH homolog groups are quantitated using the response factor of a parent PAH method compound, if available. Precision data for the alkylated PAH homologs detected in a marine sediment standard reference material (SRM 1944) also are presented to document and demonstrate method capability.

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

    PubMed

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

    2002-07-25

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

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

    PubMed Central

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

    2010-01-01

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

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

    Microsoft Academic Search

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

    2010-01-01

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

  16. Quantitation of cortisol and related 3-oxo-4-ene steroids in urine using gas chromatography\\/mass spectrometry with stable isotope-labeled internal standards

    Microsoft Academic Search

    Mario Palermo; Celso Gomez-Sanchez; Esther Roitman; Cedric H. L. Shackleton

    1996-01-01

    A method for the profiling of several important 3-oxo-4-ene urinary steroids is reported. The methodology is combined gas chromatography\\/mass spectrometry (GC\\/MS) utilizing stable isotope-labeled internal standards. The following standards were obtained or easily synthesized: [9,11,12,12-2H4]cortisol, [1,2-2H2] and [9,12,12-2H2]cortisone, [1,2-2H2]6?-hydroxycortisol, and [1,2-2H2]18-hydroxycortisol. We found the following excretions of free steroids for normal adult males and females: cortisol (males mean ± SD,

  17. Miniaturized hollow fiber assisted liquid-phase microextraction and gas chromatography–mass spectrometry for determination of benzophenone and derivates in human urine sample

    Microsoft Academic Search

    Migaku Kawaguchi; Rie Ito; Hidehiro Honda; Youji Koganei; Noriya Okanouchi; Koichi Saito; Yasuo Seto; Hiroyuki Nakazawa

    2009-01-01

    The determination of benzophenones (BPs) in human urine sample by miniaturized hollow fiber assisted liquid-phase microextraction (HF-LPME) and gas chromatography–mass spectrometry (GC–MS) is described. As analytes, BP, its metabolites benzhydrol (BP-OH) and 2-hydroxybenzophenone (2OH-BP), and its derivatives 2-hydroxy-4-methoxybenzophenone (BP-3) and 2-hydroxy-4-methoxy-4?-methylbenzophenone (BP-10) were selected. The detection limit and the quantification limit of BPs in human urine sample are 5–10 and

  18. Stir bar sorptive extraction with in situ de-conjugation and thermal desorption gas chromatography-mass spectrometry for measurement of 4-nonylphenol glucuronide in human urine sample

    Microsoft Academic Search

    Migaku Kawaguchi; Rie Ito; Yoshio Hayatsu; Hisao Nakata; Norihiro Sakui; Noriya Okanouchi; Koichi Saito; Hiroshi Yokota; Shun-ichiro Izumi; Tsunehisa Makino; Hiroyuki Nakazawa

    2006-01-01

    4-Nonylphenol glucuronide (NP-G) in human urine samples was analyzed using stir bar sorptive extraction (SBSE) with in situ de-conjugation by ?-glucuronidase and thermal desorption (TD)-gas chromatography-mass spectrometry (GC-MS). Distilled water (1ml), 1.0M ammonium acetate solution (100?l) and ?-glucuronidase (10,000unitsml?1, 10?l) were added to human urine sample (1ml), and extraction was commenced for 90min at 37°C while stirring at 250rpm with

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

    Microsoft Academic Search

    Roland F. Staack; Hans H. Maurer

    2004-01-01

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

  20. Plant- versus microbial signature in densimetric fractions of mediterranean forest soils: a study by thermochemolysis gas chromatography mass spectrometry

    NASA Astrophysics Data System (ADS)

    Rovira, Pere; Grasset, Laurent

    2015-04-01

    Plant- versus microbial signature in densimetric fractions of mediterranean forest soils: a study by thermochemolysis gas chromatography mass spectrometry The ageing of a given organic substrate decomposing in soil is strongly dependant of its microbial utilization and transformation (reworking) by the soil microflora. How far a given substrate or soil fraction has gone in this evolution is usually measured by means of molecular signatures, ratios between organic compounds which enlighten us about the origin and/or the degree of microbial reworking of a specific group of compounds: lipids, proteins, lignin, carbohydrates, etc. Owing to the biochemical heterogeneity of decomposing substrates it is unlikely that the degree of microbial reworking can be approached with a single signature. Applying a couple of them is much better, but obtaining a wide collection of molecular signatures can be time consuming. Here, instead of applying specific methods to obtain a collection of specific signatures, we apply TMAH-thermochemolysis to obtain a panoramic view of the biochemical composition of a series of densimetric fractions of soils. From the compounds identified after TMAH-thermochemolysis, a collection of indicators was obtained: (a) ratio between short and long-chained linear alkanoic acids; (b) ratio between branched and long-chained linear alkanoic acids; (c) ratio between C16 and total alpha-omega-alkanedioic acids; (d) ratio microbial to plant-derived 1-methoxyalkanes; (e) ratio syringyl to total lignin-derived phenolic compounds; (f) vanillic acid to vanillin ratio; (g) fucose/glucose ratio; and (h) xylose/glucose ratio. From these indicators a single numerical value is distilled, allowing to order a couple of densimetric fractions of soil organic matter according to its degree of microbial reworking. This approach was applied to the comparison of a couple of densimetric fractions of soil organic matter of three organic H horizons from mediterranean forest soils. Fractions were obtained by a sequential extraction with sodium polytungstate (NaPT) at density 1.6, 1.8 and 2.0, after ultrasonic disintegration of the sample. Before ultrasonic treatment, a previous extraction was done with NaPT d = 1.6, to isolate the free light fraction. Results were overall consistent in the sense that occluded fractions of density <1.8, and particularly those of density < 1.6, appear as the most microbially evolved. The free light fraction was overall the most fresh-, least evolved fraction. The dense fraction (d > 2.0), made of organomineral complexes with fine silt plus clay, was overall fresh and poorly microbially reworked. Our future work will be the application of this approach to the study of complete soil profiles and soil fractions, thus allowing to obtain a panoramic view of the stabilization of soil organic matter at different depths.

  1. Identification of volatiles from pineapple (Ananas comosus L.) pulp by comprehensive two-dimensional gas chromatography and gas chromatography/mass spectrometry.

    PubMed

    Pedroso, Marcio P; Ferreira, Ernesto C; Hantao, Leandro W; Bogusz, Stanislau; Augusto, Fabio

    2011-07-01

    Combining qualitative data from the chromatographic structure of 2-D gas chromatography with flame ionization detection (GC×GC-FID) and that from gas chromatography-mass spectrometry (GC/MS) should result in a more accurate assignment of the peak identities than the simple analysis by GC/MS, where coelution of analytes is unavoidable in highly complex samples (rendering spectra unsuitable for qualitative purposes) or for compounds in very low concentrations. Using data from GC×GC-FID combined with GC/MS can reveal coelutions that were not detected by mass spectra deconvolution software. In addition, some compounds can be identified according to the structure of the GC×GC-FID chromatogram. In this article, the volatile fractions of fresh and dehydrated pineapple pulp were evaluated. The extraction of the volatiles was performed by dynamic headspace extraction coupled to solid-phase microextraction (DHS-SPME), a technique appropriate for slurries or solid matrices. Extracted analytes were then analyzed by GC×GC-FID and GC/MS. The results obtained using both techniques were combined to improve compound identifications. PMID:21644251

  2. Determination of breath gas composition of lung cancer patients using gas chromatography/mass spectrometry with monolithic material sorptive extraction.

    PubMed

    Ma, Wen; Gao, Peng; Fan, Jun; Hashi, Yuki; Chen, Zilin

    2015-06-01

    A gas chromatographic-mass spectrometric method with monolithic material sorptive extraction (MMSE) pretreatment was developed to determine the breath gas composition in lung cancer patients. MonoTrap silica monolithic and hybrid adsorbent was selected as the extraction medium during MMSE, given its strong capacity to extract volatile organic compounds (VOC) from exhaled gas. Under the appropriate conditions, high extraction efficiency was achieved. Using the selected ion-monitoring mode, the limit of detection (signal-to-noise ratio 3) for the benzene series was 0.012-2.172?ng?L(-1) . The limit of quantitation (signal-to-noise ratio, 10) was 0.042-7.24?ng?L(-1) . The linearity range of the method was 4-400?ng?L(-1) . Average recovery of the benzene series at lower concentrations was 65-74% (20?ng?L(-1) ). The relative standard deviation of benzene series contents determined within the linear range of detection was <10% of the mean level determined. Our proposed method is simple, rapid and sensitive, and can be competently applied to determine the breath gas composition of lung cancer patients. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25421853

  3. Characterisation of the aroma profiles of different honeys and corresponding flowers using solid-phase microextraction and gas chromatography-mass spectrometry/olfactometry.

    PubMed

    Seisonen, Sirli; Kivima, Evelin; Vene, Kristel

    2015-02-15

    The aroma profiles of thirteen different honey samples from four botanical origins: heather (Calluna vulgaris), raspberry (Rubus idaeus), rape (Brassica napus), alder buckthorn (Frangula alnus) and the blossoms of the four corresponding flowers were investigated to find odour-active compounds exclusively representing specific honeys based on odour-active compounds from the blossoms. Gas-chromatography-mass spectrometry (GC-MS) and gas-chromatography-olfactometry were used to determine and identify the odour-active compounds. Data was analysed using agglomerative hierarchical clustering and correspondence analysis. Honeys from the same botanical origin clustered together; however, none of the identified compounds were exclusive to a particular honey/blossom combination. Heather honey had the flavour profile most different to the others. Isophorone and 2-methylbutyric acid were found only in heather honeys. Heather honey was characterised by having more "sweet" and "candy-like" notes, raspberry honeys had more "green" notes, while alder buckthorn had more "honey" and "floral" notes. PMID:25236195

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

    PubMed

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

    2005-10-01

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

  5. Simultaneous determination of amitraz and its metabolite residue in food animal tissues by gas chromatography-electron capture detector and gas chromatography–mass spectrometry with accelerated solvent extraction

    Microsoft Academic Search

    Huan Yu; Yanfei Tao; Tao Le; Dongmei Chen; Awais Ishsan; Yu Liu; Yulian Wang; Zonghui Yuan

    2010-01-01

    A new method has been developed for determination and confirmation of amitraz and its main metabolite, 2,4-dimethylaniline, in food animal tissues using gas chromatography-electron capture detector (GC-ECD) and gas chromatography–mass spectrometry detector (GC–MS). This method is based on a new extraction procedure using accelerated solvent extraction (ASE). It consists of an n-hexane\\/methanol extraction step, a cleaning-up step by BakerBond octadecyl

  6. Determination of pesticides in aqueous samples by solid-phase microextraction in-line coupled to gas chromatography-mass spectrometry.

    PubMed

    Eisert, R; Levsen, K

    1995-11-01

    A multiresidue method was developed for the determination of nitrogen- and phosphorous-containing pesticides (amines, anilides, phosphorothioates, and triazines) by solid-phase microextraction (SPME) in-line coupled to gas chromatography-mass spectrometry (GC/MS). The 85-µm polyacrylate fiber was first dipped into the aqueous sample for a given time and then directly introduced into the heated injector of the gas chromatography-mass spectrometer, where the analytes are thermally desorbed. The method was evaluated with respect to the limit of detection, linearity, and precision. The limit of detection [selected ion monitoring (SIM) mode] depends on the compound and varies from 5 to 90 ng/L. The method is linear over at least 3 orders of magnitude with coefficients of correlation usually ?0.996. In general, the coefficient of variation (precision) is <10%. The partitioning of the analyte between the aqueous phase and the polymeric phase depends on the hydrophobicity of the compound as expressed by the octanol-water partitioning coefficient P ow. The addition of sodium chloride has a strong effect on the extraction efficiency. This effect increases with decreasing hydrophobicity (increasing polarity) of the compound.The triazines atrazine, simazine, and terbuthylazine were first identified and quantified in water samples from the effluent of sewage plants by SPME-gas chromatography-nitrogen-phosphorus detection (GC/NPD). For such a complex matrix GC/NPD is not sufficiently selective for an unambiguous identification at low levels (<1 ppb) of pesticides. Selectivity may be enhanced by using SMPE-GC/MS in the SIM mode with three characteristic ions for each pesticide. This method allows an unequivocal identification and quantification at low levels of pesticides in environmental samples.At a target limit of detection below 100 ng/L, SPME-GC/MS represents a very simple, fast, selective, and solvent-free multimethod for the extraction and determination of these nitrogen- and phosphorous-containing pesticides from aqueous samples. PMID:24214059

  7. [Determination of fipronil and its metabolites in tea by solid-phase microextraction coupled with gas chromatography and gas chromatography-mass spectrometry].

    PubMed

    Zhou, Yu; Xu, Dunming; Chen, Dajie; Zhang, Zhigang; Zheng, Xianghua; Fang, Enhua

    2011-07-01

    An effective multi-residue method for the trace analysis of fipronil and four metabolites (fipronil-desulfinyl, fipronil-sulfide, fipronil-sulfone and fipronil-carboxamide) in tea was developed based on solid-phase microextraction coupled with gas chromatography (SPME-GC). The targets were extracted with a fused-silica fiber coated with 85 microm polyacrylate (PA). The extraction was performed in a pH 9 buffer (containing 0.1 mol/L boracic acid, 0.1 mol/L KCI and 0.1 mol/L NaOH) at 60 degrees C and under 2500 r/min for 30 min. With the concentration range of 2-10 microg/kg, the recoveries ranged from 71.2% to 109.3% and the relative standard deviations (RSDs) were lower than 10% (n = 6). The limits of detection (LODs) and limits of quantitation (LOQs) of the studied compounds ranged from 0.3 microg/kg to 1.2 microg/kg and 1.0 microg/kg to 4.0 microg/kg, respectively, with the values well below the residue limits set by Japan, European Union and China. By the proposed method, 1 positive samples of 30 tea samples were found with fipronil and fipronil-sulfone. The identification of the method was done by gas chromatography-mass spectrometry (GC-MS). The method can be applied as a monitoring tool for tea, in the investigation of food to fipronil and its metabolites. PMID:22097792

  8. Gas chromatography-mass spectrometry determination of the pentafluorobenzoyl derivative of methylhydrazine in false morel (Gyromitra esculenta) as a monitor for the content of the toxin gyromitrin.

    PubMed

    Arshadi, Mehrdad; Nilsson, Calle; Magnusson, Bengt

    2006-09-01

    The main toxic compound found in false morel (Gyromitra esculenta) is acetaldehyde-N-methyl-N-formylhydrazone (gyromitrin). This paper describes a method of determining the total hydrazones content based on acid hydrolysis of gyromitrin and other related hydrazones in air-dried false morel followed by derivatisation of methylhydrazine with pentafluorobenzoyl chloride. The derivative, tris-pentafluorobenzoyl methylhydrazine (tris-PFB-MH) is analyzed by gas chromatography-mass spectrometry. The overall precision of the method is better than 10% (relative standard deviation) for 0.5 ng/microl methylhydrazine in solution. The minimum detectable concentration of methylhydrazine (tris-PFB-MH) by this method is estimated to be approximately 12 pg/microl, which is equal to 0.3 microg/g dry matter (DM) of false morel. PMID:16782115

  9. Determination of seven pyrethroids biocides and their synergist in indoor air by thermal-desorption gas chromatography/mass spectrometry after sampling on Tenax TA ® passive tubes.

    PubMed

    Raeppel, Caroline; Appenzeller, Brice M; Millet, Maurice

    2015-01-01

    A method coupling thermal desorption and gas chromatography/mass spectrometry (GC/MS) was developed for the simultaneous determination of 7 pyrethroids (allethrin, bifenthrin, cyphenothrin, imiprothrin, permethrin, prallethrin and tetramethrin) and piperonyl butoxide adsorbed on Tenax TA(®) passive samplers after exposure in indoor air. Thermal desorption was selected as it permits efficient and rapid extraction without solvent used together with a good sensitivity. Detection (S/N>3) and quantification (S/N>10) limits varied between 0.001 ng and 2.5 ng and between 0.005 and 10 ng respectively with a reproducibility varied between 14% (bifenthrin) and 39% (permethrin). The method was used for the comparison indoor air contamination after low-pressure spraying and fumigation application in a rubbish chute situated in the basement of a building. PMID:25281107

  10. Resolution of co-eluting compounds of Cannabis Sativa in comprehensive two-dimensional gas chromatography/mass spectrometry detection with Multivariate Curve Resolution-Alternating Least Squares.

    PubMed

    Omar, Jone; Olivares, Maitane; Amigo, José Manuel; Etxebarria, Nestor

    2014-04-01

    Comprehensive Two Dimensional Gas Chromatography - Mass Spectrometry (GC × GC/qMS) analysis of Cannabis sativa extracts shows a high complexity due to the large variety of terpenes and cannabinoids and to the fact that the complete resolution of the peaks is not straightforwardly achieved. In order to support the resolution of the co-eluted peaks in the sesquiterpene and the cannabinoid chromatographic region the combination of Multivariate Curve Resolution and Alternating Least Squares algorithms was satisfactorily applied. As a result, four co-eluting areas were totally resolved in the sesquiterpene region and one in the cannabinoid region in different samples of Cannabis sativa. The comparison of the mass spectral profiles obtained for each resolved peak with theoretical mass spectra allowed the identification of some of the co-eluted peaks. Finally, the classification of the studied samples was achieved based on the relative concentrations of the resolved peaks. PMID:24607138

  11. 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

  12. Gas chromatography-mass spectrometric analysis of products from on-line pyrolysis/silylation of plant gums used as binding media

    NASA Astrophysics Data System (ADS)

    Chiantore, Oscar; Riedo, Chiara; Scalarone, Dominique

    2009-07-01

    Plant gums are complex polysaccharides used in the field of cultural heritage especially as binding media. Classification of polysaccharides may be achieved on the basis of monosaccharides composition after cleavage of glycosidic bond. Characterization of plant gums in works of art is complicated by the necessity of to use a method minimally invasive and requiring a small mount of sample. Pyrolisys is an useful method to obtain polysaccharides decomposition and generally pyrolysis products can be identified by the use of gas chromatography-mass spectrometry. This paper describes a method where two plant gums, arabic and tragacanth, were pyrolized in presence of silylating agents (HMDS e BSTFA alone and with TMCS as catalyst) using an on-line Py-GC/MS apparatus. Some characteristic trimethylsilyl derivatives of monosaccharides were identified on the basis of mass spectra. The presence of characteristic pyrolysis products of sugars allows to distinguish the two gums.

  13. Metabolite profiling of Camellia sinensis by automated sequential, multidimensional gas chromatography/mass spectrometry reveals strong monsoon effects on tea constituents.

    PubMed

    Kowalsick, Amanda; Kfoury, Nicole; Robbat, Albert; Ahmed, Selena; Orians, Colin; Griffin, Timothy; Cash, Sean B; Stepp, John Richard

    2014-11-28

    Seasonal variation in tea (Camellia sinensis (L.) Kuntze; Theaceae) chemistry was investigated using automated sequential, multidimensional gas chromatography/mass spectrometry (GC-GC/MS). Metabolite libraries were produced for teas harvested from the Bulang Mountains in Yunnan, China before and after the onset of the East Asian Monsoon. A total of 201 spring and 196 monsoon metabolites were identified, with 169 common and 59 seasonally unique compounds. An additional 163 metabolites were detected but their identity could not be confirmed. Spectral deconvolution of GC/MS data was used to measure the relative concentrations in the teas. Within each family individual metabolite concentrations increased, decreased and stayed the same. The major constituents in both teas were linalool (28%), geraniol (13%), ?-terpineol (10%), hotrienol (4%) and nerol (3%). This work provides the foundation to monitor seasonal variations of tea chemistry. PMID:25454147

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

    PubMed

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

    2014-11-28

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

  15. Analyses of the wood preservative component N-cyclohexyl-diazeniumdioxide in impregnated pine sapwood by direct thermal desorption-gas chromatography-mass spectrometry.

    PubMed

    Jüngel, Peter; de Koning, Sjaak; Brinkman, Udo A Th; Melcher, Eckhard

    2002-04-12

    Investigations concerning the qualitative and quantitative determination of the organic wood preservative component N-cyclohexyl-diazeniumdioxide (HDO) in treated timber were carried out by means of direct thermal desorption-gas chromatography-mass spectrometry (DTD-GC-MS). It could be shown that the identification of HDO in treated pine sapwood (Pinus sylyestris L.) is relatively simple using this analytical technique. Quantification of this active ingredient can be carried out using the peak area of the specific mass fragment m/z 114. A calibration curve with a high correlation coefficient was obtained in the range from 40 to 550 mg HDO per kg timber. Furthermore it can be deduced that the results obtained are characterised by an excellent reproducibility with standard deviations ranging from 5 to 10% in general. For the chosen experimental set up a detection limit of 4 mg HDO per kg treated pine sapwood was calculated, although merely 20% of the active ingredient was desorbed. PMID:12058933

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

    PubMed

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

    2014-02-26

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

  17. Applications of solid-phase microextraction and gas chromatography/mass spectrometry (SPME-GC/MS) in the study of grape and wine volatile compounds.

    PubMed

    Panighel, Annarita; Flamini, Riccardo

    2014-01-01

    Volatile compounds are responsible for the wine "bouquet", which is perceived by sniffing the headspace of a glass, and of the aroma component (palate-aroma) of the overall flavor, which is perceived on drinking. Grape aroma compounds are transferred to the wine and undergo minimal alteration during fermentation (e.g., monoterpenes and methoxypyrazines); others are precursors of aroma compounds which form in winemaking and during wine aging (e.g., glycosidically-bound volatile compounds and C13-norisoprenoids). Headspace solid phase microextraction (HS-SPME) is a fast and simple technique which was developed for analysis of volatile compounds. This review describes some SPME methods coupled with gas chromatography/mass spectrometry (GC/MS) used to study the grape and wine volatiles. PMID:25529017

  18. Simultaneous microdetermination of capsaicin and its four analogues by using high-performance liquid chromatography and gas chromatography--mass spectrometry.

    PubMed

    Iwai, K; Suzuki, T; Fujiwake, H; Oka, S

    1979-04-21

    An improved method is described for the simultaneous determination of capsaicin and its analogues at levels from nanograms to micrograms using high-performance liquid chromatography (HPLC) and gas chromatography--mass spectrometry. This method consists of two steps: firstly, purification and determination of total capsaicinoid by HPLC, and secondly, the simultaneous determination of capsaicin and its analogues by mass chromatography (MC) or mass fragmentography (MF). Crude extracts of capsaicinoid were purified with a Zorbax SIL column. Total capsaicinoid was detected at 235 nm and measured automatically by a microcomputer. It was collected, evaporated, trimethylsilylated and subjected to MC or MF. After monitoring the molecular ions of trimethylsilyl derivatives of capsaicinoid and the internal standard, the absolute contents of each analogue were determined by computer. By using this method, capsaicin and all of its analogues can be determined simultaneously at levels from micrograms to nanograms without any interferences from other components. PMID:548533

  19. Determination of volatile organic contaminants in bulk oils (edible, injectable, and other internal medicinal) by purge-and-trap gas chromatography/mass spectrometry

    SciTech Connect

    Thompson, D.W. [Food and Drug Administration, Atlanta, GA (United States)

    1994-05-01

    Purge-and-trap gas chromatography/mass spectrometry is evaluated for the quantitation of part-per-billion levels of volatile organic contaminants in bulk vegetable oils. Results using 2 purge techniques (direct purging of the heated oil and purging after dispersing the oil on an aluminum oxide powder) and 2 quantitative methods (standard curve and deuterium-labeled internal standard addition) are reported. Twenty volatile compounds and 8 vegetable oils were investigated. Recovery data and estimated detection limits for each compound are reported for each purge technique. Generally acceptable recoveries (70-130% for more than 90% of the analyte spikes) and acceptable detection levels (approximately 4-10 ppb) were obtained for all compounds using either the external standard curve of the deuterium-isotope-labeled internal standard. The use of a dispersant (such as alumina) for sample purging resulted in poor recoveries of the highly volatile contaminants. 16 refs., 3 figs., 4 tabs.

  20. Metabolomic profiling of human follicular fluid from patients with repeated failure of in vitro fertilization using gas chromatography/mass spectrometry

    PubMed Central

    Xia, Lan; Zhao, Xiaoming; Sun, Yun; Hong, Yan; Gao, Yuping; Hu, Shuanggang

    2014-01-01

    Objective: To establish a gas chromatography/mass spectrometry (GC/MS)-based metabolomics method to compare the metabolites in the follicular fluid (FF) from patients with in vitro fertilization (IVF) and repeated IVF failure (RIF). Methods: A prospective study was employed in Center for Reprodutive Medcine, Renji Hospital, Shanghai, China, between January and October 2010. FF samples were collected from 13 patients with RIF and 15 patients who achieved pregnancy after the first IVF cycle. Results: Partial least squares (PLS) discriminant analysis of the PCA data revealed that the samples were scattered into two different regions. FF from the two groups differed with respect to 20 metabolites. FF from RIF group showed elevated levels of several amino acids (valine, threonine, isoleucine, cysteine, serine, proline, alanine, phenylalanine, lysine, methionine and ornithine), and reduced levels of dicarboxylic acids, cholesterol and some organic acids. Conclusions: The studies corroborated successful determination of the levels of metabolite in the FF. PMID:25400819

  1. Fast determination of octinoxate and oxybenzone uv filters in swimming pool waters by gas chromatography/mass spectrometry after solid-phase microextraction.

    PubMed

    Y?lmazcan, Ö; Kanakaki, C; Izgi, B; Rosenberg, E

    2015-07-01

    A fast gas chromatography/mass spectrometry method was developed and validated for the analysis of the potential endocrine disrupters octinoxate and oxybenzone in swimming pool water samples based on the solvent-free solid-phase microextraction technique. The low-pressure gas chromatography/mass spectrometry method used for the fast identification of UV filter substances was compared to a conventional method in terms of sensitivity and speed. The fast method proposed resulted in 2 min runs, leading to an eightfold decrease in the total analysis time and a sevenfold improvement in detection limits. The main parameters affecting the solid-phase microextraction process were also studied in detail and the optimized conditions were as follows: fiber coating, polyacrylate; extraction mode, direct immersion; extraction temperature, 25°C; sample volume, 5 mL; extraction time 45 min; pH 6.5. Under the optimized conditions, a linear response was obtained in the concentration range of 0.5-25 ?g/L with correlation coefficients in the range 0.990-0.999. The limits of detection were 0.17-0.29 ?g/L, and the recoveries were 80-83%. Combined method uncertainty was assessed and found to be less than 7% for both analytes for concentrations equal to or higher than 5 ?g/L. Pool water samples were analyzed to demonstrate the applicability of the proposed method. Neither octinoxate nor oxybenzone were detected in the swimming pool water samples at concentrations above the respective limits of detection. PMID:25931007

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

    NASA Astrophysics Data System (ADS)

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

    2008-10-01

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

  3. Polycyclic aromatic hydrocarbon emissions in diesel exhaust using gas chromatography-mass spectrometry with programmed temperature vaporization and large volume injection

    NASA Astrophysics Data System (ADS)

    Vieira de Souza, Carolina; Corrêa, Sergio Machado

    2015-02-01

    Diesel engines are significant sources of Polycyclic Aromatic Compounds (PAHs) in urban atmospheres. These compounds are widely known for their carcinogenic potential and mutagenic properties. In this study, a method was developed for the analysis of 16 priorities PAHs using gas chromatography-mass spectrometry (GC-MS) with programmable temperature vaporizer large volume injection (PTV-LVI), which allowed to be obtained detection limits below 2.0 ng mL-1. This method was evaluated in samples from stratified particulate matter and gas phase from the emissions of diesel vehicle employing diesel commercial S10 (sulfur 10 mg L-1) and B5 (biodiesel 5% v/v). A sampling system that does not employ exhaust products dilution was used to evaluate the PAHs gas-particle partition. Six PAHs were identified in extracts and gas-phase PAHs took percentage of 80% in the total PAHs emissions. The sampling system without dilution not caused a strong nucleation/condensation of the most volatile PAHs. PAHs size-particle distribution was found in higher levels in the accumulation mode.

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

    Microsoft Academic Search

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

    2009-01-01

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

  5. Identification of Bound Nitro Musk-Protein Adduct in Fish Liver By Gas Chromatography-Mass Sectrometry: Biotransformation, Dose-Response and Toxicokinetics of Nitro Musk Metabolites Protein Adducts in Trout Liver as Biomarker of Exposure

    EPA Science Inventory

    Ubiquitous occurrences of synthetic nitro musks are evident in the literature. The In vivo analysis of musk xylene (MX) and musk ketone (MK) - protein adducts in trout liver have been performed by gas chromatography-mass spectrometry using selected ion monitoring (GC-SIM-MS). Bio...

  6. 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...

  7. Characterization of novel single-variety oxygenated sesquiterpenoid hop oil fractions via headspace solid-phase microextraction and gas chromatography-mass spectrometry/olfactometry.

    PubMed

    Van Opstaele, Filip; Praet, Tatiana; Aerts, Guido; De Cooman, Luc

    2013-11-01

    The volatile composition of novel varietal oxygenated sesquiterpenoid hop oil fractions ("spicy essences") was characterized by headspace solid-phase microextraction in combination with gas chromatography-mass spectrometry. Oxygenated sesquiterpenes represent the major chemical compound class, accounting for at least 65% of the total volatile fraction. In addition to oxygenated sesquiterpenes, spicy hop essences consist of several ketones, sesquiterpene and monoterpene hydrocarbons, and a relatively high number of unidentified compounds. On the basis of their relative composition, spicy hop essences can be fully differentiated according to their varietal origin. Multidimensional gas chromatography in combination with time-of-flight mass spectrometry on spicy hop essence cv. Spalter Select further demonstrated the enormous complexity of this particular hop oil fraction. The aromagram obtained via gas chromatography-olfactometry comprised nine odor-active regions described in terms of "citrus", "green", "haylike", "earthy", "woody", and "spicy". 2-Undecanone, 2-tridecanone, ?-cadinene, ?-calacorene, calarene, humuladienone, caryolan-1-ol, caryophyllene oxide enantiomers, and humulene epoxide II are tentatively identified in the odor-active zones. PMID:24152289

  8. Accuracy profile validation of a new method for carbon monoxide measurement in the human blood using headspace-gas chromatography-mass spectrometry (HS-GC-MS).

    PubMed

    Varlet, V; De Croutte, E Lagroy; Augsburger, M; Mangin, P

    2012-01-01

    The aim of our study was to provide an innovative headspace-gas chromatography-mass spectrometry (HS-GC-MS) method applicable for the routine determination of blood CO concentration in forensic toxicology laboratories. The main drawback of the GC/MS methods discussed in literature for CO measurement is the absence of a specific CO internal standard necessary for performing quantification. Even if stable isotope of CO is commercially available in the gaseous state, it is essential to develop a safer method to limit the manipulation of gaseous CO and to precisely control the injected amount of CO for spiking and calibration. To avoid the manipulation of a stable isotope-labeled gas, we have chosen to generate in a vial in situ, an internal labeled standard gas ((13)CO) formed by the reaction of labeled formic acid formic acid (H(13)COOH) with sulfuric acid. As sulfuric acid can also be employed to liberate the CO reagent from whole blood, the procedure allows for the liberation of CO simultaneously with the generation of (13)CO. This method allows for precise measurement of blood CO concentrations from a small amount of blood (10 ?L). Finally, this method was applied to measure the CO concentration of intoxicated human blood samples from autopsies. PMID:22169058

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

    PubMed

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

    2014-12-17

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

  10. Confirmation of cocaine exposure by gas chromatography–mass spectrometry of urine extracts after methylation of benzoylecgonine

    Microsoft Academic Search

    Maur??cio Yonamine; Ovandir Alves Silva

    2002-01-01

    Volatility and thermal stability are necessary physical–chemical properties for analysing a substance by gas chromatography. A derivatization step is required before gas chromatography of benzoylecgonine (the main metabolite of cocaine). In the literature, reactions such as silylation, perfluoroalkylation or alkylation are the most frequently used to derivatize benzoylecgonine. However, they allow the formation of products sensitive to moisture or require

  11. 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

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

    PubMed

    Niebler, Johannes; Buettner, Andrea

    2015-01-01

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

  13. Purge-assisted headspace solid-phase microextraction combined with gas chromatography-mass spectrometry for determination of chlorophenols in aqueous samples.

    PubMed

    Ho, Hsin-Pin; Lee, Ren-Jye; Lee, Maw-Rong

    2008-12-12

    A simple, economical and very effective method is demonstrated for simultaneous determination of 2,4-dichlorophenol, 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol and pentachlorophenol, in aqueous samples, by using purge-assisted headspace solid-phase microextraction (PA/HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). In the new method, purging the sample enhances the removal of the trace chlorophenols without derivatization from the matrices to the headspace. Extraction parameters including extraction temperature, purge gas flow rate and extraction time were systematically investigated. Under optimal conditions, the relative standard deviations (RSDs) were 4-11% at 50 pg/mL and 5-14% at 5 pg/mL, respectively. The recoveries were in the range of 83-114%. Detection limits were determined at the fg level. These results indicate that PA/HS-SPME provides a significant contribution to highly efficient extraction of semi-volatile CPs, especially for pentachlorophenol, which has the smallest Henry's constant and large octanol-water partitioning coefficient. In addition, the proposed method was successfully applied to the analysis of chlorophenols in landfill leachate. New perspectives are opened for headspace extraction of relatively low vapor pressure compounds in complex matrices. PMID:18990397

  14. Structural Characterisation of Organic Matter in Fine Tropospheric Aerosol by Pyrolysis-Gas Chromatography-Mass Spectrometry

    Microsoft Academic Search

    A. Gelencsér; T. Mészáros; M. Blazsó; Gy. Kiss; Z. Krivácsy; A. Molnár; E. Mészáros

    2000-01-01

    The organic matter in tropospheric aerosol plays animportant, yet undetermined role in atmosphericprocesses. The bulk of organic carbon representing asignificant part of the fine aerosol mass is bound toa polymeric matter whose structure and properties areto date largely unknown. Here we use thefingerprinting technique of derivatization pyrolysis-gas chromatography-massspectrometry tosubstantiate that in terms of chemical structure partof this polymer in rural

  15. GAS CHROMATOGRAPHY-MASS SPECTROMETRY (GC-MS) TECHNIQUES FOR METABOLIC FLUX ANALYSIS OF THE BIFIDO SHUNT PATHWAY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The presence of the Bifido shunt in Bifidobacterium is predicted to lead to the uptake and metabolic conversion of fructose to acetate. We propose an approach to quantifying the carbon flux through the Bifido shunt by measuring specific **13C-labeled carbohydrate-derived isotopomers by gas chromato...

  16. Characterization of resins and drying oils used to manufacture varnishes of ancient violins by gas chromatography-mass spectrometry

    Microsoft Academic Search

    C. Benoit; J. P. Echard; J. Peris-Vicente; J. V. Gimeno-Adelantado

    2006-01-01

    A study for characterization of natural resins and drying oils employed in varnishes used in ancient violins was made using gas chromatography coupled to mass spectrometry. This method requires prior derivatization of the samples by methanolysis to release and volatilize the terpenic and fatty acids, and sylilation in order to volatilize the alcohols. Derivatization time and temperature were optimized and

  17. One-step microwave-assisted headspace solid-phase microextraction for the rapid determination of synthetic polycyclic musks in oyster by gas chromatography-mass spectrometry.

    PubMed

    Wu, Shin-Fang; Liu, Li-Lian; Ding, Wang-Hsien

    2012-07-15

    A rapid, simple and solvent-free procedure was developed for the determination of synthetic polycyclic musks in oyster samples by using one-step microwave-assisted headspace solid-phase microextraction (MA-HS-SPME) and gas chromatography-mass spectrometry (GC-MS). Two commonly used synthetic polycyclic musks, galaxolide (HHCB) and tonalide (AHTN), were selected in the method development and validation. The parameters (microwave irradiation power, extraction time, amount of water added, pH value and addition of NaCl) affecting the extraction efficiency of analytes from oyster slurry were systematically investigated and optimised. The best extraction conditions were achieved when the oyster tissue mixed with 10-mL deionised water (containing 3g of NaCl in a 40-mL sample-vial) was microwave irradiated at 80 W for 5 min. The limit of quantification (LOQ) was 0.1 ng/g in 5-g of wet tissue. The good precision and accuracy of one-step MA-HS-SPME coupled with GC-MS for the determination of trace level of AHTN in oyster samples was also demonstrated. PMID:25683427

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

    PubMed

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

    2012-03-01

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

  19. Simultaneous determination of parabens and synthetic musks in water by stir-bar sorptive extraction and thermal desorption-gas chromatography-mass spectrometry.

    PubMed

    Ramírez, Noelia; Borrull, Francesc; Marcé, Rosa Maria

    2012-02-01

    This study focuses on a method for simultaneously determining personal care products in a wide range of polarities in different water matrices. The method is based on stir-bar sorptive extraction followed by thermal desorption-gas chromatography-mass spectrometry. Prior to extraction, the parabens were acetylated to improve their affinity for the polydimethylsiloxane phase of the stir bar. The method showed good linearity, repeatability and reproducibility between days for all compounds and limits of detection at low ng/L levels (between 0.02 and 0.3?ng/L). The proposed method is also environmentally friendly, because it does not use organic solvents, and reduces the risk of external pollution, due to the minimal manipulation of the sample required. The method developed was successfully applied for the analysis of personal care products in different kinds of water matrices: influents and effluents of urban and industrial wastewater treatment plants, effluents of a reverse osmosis treatment plant and river waters. The influents of urban treatment plants generally showed the highest values for synthetic musks, with concentrations of up to 2219?ng/L of galaxolide, whereas the highest concentrations of parabens were detected in the industrial treatment plants influents. PMID:22282419

  20. Nanoscale-supported heteropoly acid as a new fiber coating for solid-phase microextraction coupled with gas chromatography-mass spectrometry.

    PubMed

    Abolghasemi, Mir Mahdi; Hassani, Sona; Rafiee, Ezzat; Yousefi, Vahid

    2015-02-13

    In the present study, 12-tungstophosphoric (PW) acid as heteropoly acid, supported on silica-coated ?-Fe2O3 nanoparticles (NPs), was used as a new fiber coating for solid-phase microextraction (SPME). The ?-Fe2O3@SiO2-PW nanocomposite with high surface area was synthesized and characterized by SEM and FT-IR. The prepared nanocomposite was immobilized on a stainless steel wire for fabrication of the SPME fiber. The fiber was evaluated for the extraction of some phenolic compounds (PCs) from water sample in combination with gas chromatography-mass spectrometry (GC-MS). A one-at-a-time optimization strategy was applied for optimizing the important extraction parameters such as extraction temperature, extraction time, ionic strength, stirring rate, pH, and desorption temperature and time. In optimum conditions, the repeatability for one fiber (n=3), expressed as relative standard deviation (R.S.D. %), was between 4.8% and 9.6% for the test compounds. The detection limits for the studied compounds were between 0.004 and 0.05 pg mL(-1). The developed method offers the advantage of being simple to use, with shorter analysis time, lower cost of equipment, thermal stability of fiber and high relative recovery in comparison to conventional methods of analysis. PMID:25618361

  1. Simultaneous quantification of Aroclor mixtures in soil samples by gas chromatography/mass spectrometry with solid phase microextraction using partial least-squares regression.

    PubMed

    Zhang, Mengliang; Harrington, Peter de B

    2015-01-01

    Multivariate partial least-squares (PLS) method was applied to the quantification of two complex polychlorinated biphenyls (PCBs) commercial mixtures, Aroclor 1254 and 1260, in a soil matrix. PCBs in soil samples were extracted by headspace solid phase microextraction (SPME) and determined by gas chromatography/mass spectrometry (GC/MS). Decachlorinated biphenyl (deca-CB) was used as internal standard. After the baseline correction was applied, four data representations including extracted ion chromatograms (EIC) for Aroclor 1254, EIC for Aroclor 1260, EIC for both Aroclors and two-way data sets were constructed for PLS-1 and PLS-2 calibrations and evaluated with respect to quantitative prediction accuracy. The PLS model was optimized with respect to the number of latent variables using cross validation of the calibration data set. The validation of the method was performed with certified soil samples and real field soil samples and the predicted concentrations for both Aroclors using EIC data sets agreed with the certified values. The linear range of the method was from 10?gkg(-1) to 1000?gkg(-1) for both Aroclor 1254 and 1260 in soil matrices and the detection limit was 4?gkg(-1) for Aroclor 1254 and 6?gkg(-1) for Aroclor 1260. This holistic approach for the determination of mixtures of complex samples has broad application to environmental forensics and modeling. PMID:25216382

  2. 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

  3. In situ solid-phase microextraction and post on-fiber derivatization combined with gas chromatography-mass spectrometry for determination of phenol in occupational air.

    PubMed

    Es-haghi, Ali; Baghernejad, Masoud; Bagheri, Habib

    2012-09-12

    A method based on solid-phase microextraction (SPME) followed by on-fiber derivatization and gas chromatography-mass spectrometry detection (GC-MS) for determination of phenol in air was developed. Three different types of SPME fibers, polar and non-polar poly(dimethylsiloxane) (PDMS) and polyethylene glycol (PEG) were synthesized using sol-gel technology and their feasibility to the sampling of phenol were investigated. Different derivatization reagents for post on-fiber derivatization of phenol were studied. Important parameters influencing the extraction and derivatization process such as type of fiber coating, type and volume of derivatizing reagent, derivatization time and temperature, extraction time, and desorption conditions were investigated and optimized. The developed method is rapid, simple, easy and inexpensive and offers high sensitivity and reproducibility. Under the optimized conditions, the detection limit of the method was 5 ng L(-1) using selected ion monitoring (SIM) mode. The inter-day and intra-day precisions of the developed method under optimized conditions were below 10%, and the method shows linearity in the range of 20 ng L(-1) to 500 ?g L(-1) with the correlation coefficient of >0.99. The optimized method was applied to the sampling of phenol from some biologics production areas. The compared results obtained using current and standard methods were shown to be satisfactory. PMID:22884202

  4. Multivariate study of parameters in the determination of pesticide residues in apple by headspace solid phase microextraction coupled to gas chromatography-mass spectrometry using experimental factorial design.

    PubMed

    Abdulra'uf, Lukman Bola; Tan, Guan Huat

    2013-12-15

    Solid-phase microextraction (SPME) is a solvent-less sample preparation method which combines sample preparation, isolation, concentration and enrichment into one step. In this study, multivariate strategy was used to determine the significance of the factors affecting the solid phase microextraction of pesticide residues (fenobucarb, diazinon, chlorothalonil and chlorpyrifos) using a randomised factorial design. The interactions and effects of temperature, time and salt addition on the efficiency of the extraction of the pesticide residues were evaluated using 2(3) factorial designs. The analytes were extracted with 100 ?m PDMS fibres according to the factorial design matrix and desorbed into a gas chromatography-mass spectrometry detector. The developed method was applied for the analysis of apple samples and the limits of detection were between 0.01 and 0.2 ?g kg(-)(1), which were lower than the MRLs for apples. The relative standard deviations (RSD) were between 0.1% and 13.37% with average recovery of 80-105%. The linearity ranges from 0.5-50 ?g kg(-)(1) with correlation coefficient greater than 0.99. PMID:23993624

  5. Two-dimensional gas chromatography/mass spectrometry, physical property modeling and automated production of component maps to assess the weathering of pollutants.

    PubMed

    Antle, Patrick M; Zeigler, Christian D; Livitz, Dimitri G; Robbat, Albert

    2014-10-17

    Local conditions influence how pollutants will weather in subsurface environments and sediment, and many of the processes that comprise environmental weathering are dependent upon these substances' physical and chemical properties. For example, the effects of dissolution, evaporation, and organic phase partitioning can be related to the aqueous solubility (SW), vapor pressure (VP), and octanol-water partition coefficient (KOW), respectively. This study outlines a novel approach for estimating these physical properties from comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC/MS) retention index-based polyparameter linear free energy relationships (LFERs). Key to robust correlation between GC measurements and physical properties is the accurate and precise generation of retention indices. Our model, which employs isovolatility curves to calculate retention indices, provides improved retention measurement accuracy for families of homologous compounds and leads to better estimates of their physical properties. Results indicate that the physical property estimates produced from this approach have the same error on a logarithmic-linear scale as previous researchers' log-log estimates, yielding a markedly improved model. The model was embedded into a new software program, allowing for automated determination of these properties from a single GC×GC analysis with minimal model training and parameter input. This process produces component maps that can be used to discern the mechanism and progression of how a particular site weathers due to dissolution, organic phase partitioning, and evaporation into the surrounding environment. PMID:25223613

  6. [Determination of ultraviolet filters in environmental aqueous samples by dispersive liquid-liquid microextraction with online derivatization-gas chromatography-mass spectrometry].

    PubMed

    Li, Jian; Xu, Lanying; Xue, Shuwen; Xu, Li

    2014-10-01

    A method of dispersive liquid-liquid microextraction (DLLME) combined with online derivatization-gas chromatography-mass spectrometry (GC-MS) was developed for the determination of benzophenone-type ultraviolet (UV) filers (BPs) in environmental aqueous samples. It is found that the online derivatization was superior to the off-line derivatization with its simplicity, high reaction efficiency and less consumption of potential poisonous reagents. The influential factors for online derivatization, including the temperature of the injection port, the splitless time, the proportion of derivatization reagent and sample solution, were initially optimized. In addition, the influential factors for DLLME, including the type of the extractant and dispersing solvent, the proportion of the extractant and the dispersing solvent, the volume of sample solution, the pH and the salt concentration of the sample solution were individually optimized in detail. Under the optimized derivatization and DLLME conditions, the limits of detection for the six BPs, benzophenone, 2,4-dihydroxybenzophenone, oxybenzone, 4- hydroxybenzophenone, octabenzone and 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, ranged from 0.011 to 0.15 ?g/L. The intra-day and inter-day relative standard deviations varied from 0.7% to 16.6%. The method was applied to the analysis of lake and river water with good recoveries. It is cost effective, reliable, easy to operate, environment-friendly and promising in the real applications. PMID:25739276

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

    PubMed

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

    2015-06-15

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

  8. Determination of sex-based differences in serum ?-linoleic acid and dihomo-?-linoleic acid using gas chromatography-mass spectrometry.

    PubMed

    Onozato, Mayu; Nishikiori, Minami; Iizuka, Hideaki; Ichiba, Hideaki; Sadamoto, Kiyomi; Fukushima, Takeshi

    2015-08-01

    Because serum unsaturated fatty acids can provide useful information on disease diagnosis, the simultaneous determination of several fatty acids in small volumes of human serum would be beneficial for clinical applications. In the present study, serum fatty acids were extracted with n-heptane/chloroform from 10?L of serum collected from 26 healthy Japanese subjects (11 men, ages 23-37 years; 15 women, ages 18-37 years) after deproteinization with perchloric acid, derivatization to their methyl ester using p-toluenesulfonic acid as an acid catalyst, and subsequent separation and measurement by gas chromatography-mass spectrometry (GC-MS) in the selected ion monitoring mode. Nine types of fatty acids (palmitoleic acid [PLA], oleic acid [OA], lenoleic acid [LA], ?-linolenic acid [GLA], ?-linolenic acid [ALA], dihomo-GLA [DGLA], arachidonic acid [AA], eicosapentaenoic acid [EPA], and docosahexaenoic acid [DHA]) were analyzed in the serum within 35 min by GC-MS. The concentrations of these fatty acids in serum ranged from 3.64±0.38?M (GLA) to 413±26.3 ?M (LA). Among these nine fatty acids, GLA and DGLA levels were significantly lower in women than in men (p=0.0034 and 0.0012, respectively), suggesting that there may be sex-based differences in the biosynthetic production or metabolic processes of GLA and DGLA in humans. PMID:26113452

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

    PubMed

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

    2015-07-31

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

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

    PubMed

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

    2003-05-30

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

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

    PubMed

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

    2006-09-15

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

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

    PubMed

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

    2012-11-30

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

  13. 13C-tracer and gas chromatography-mass spectrometry analyses reveal metabolic flux distribution in the oleaginous microalga Chlorella protothecoides.

    PubMed

    Xiong, Wei; Liu, Lixia; Wu, Chao; Yang, Chen; Wu, Qingyu

    2010-10-01

    The green alga Chlorella protothecoides has received considerable attention because it accumulates neutral triacylglycerols, commonly regarded as an ideal feedstock for biodiesel production. In order to gain a better understanding of its metabolism, tracer experiments with [U-(13)C]/[1-(13)C]glucose were performed with heterotrophic growth of C. protothecoides for identifying the metabolic network topology and estimating intracellular fluxes. Gas chromatography-mass spectrometry analysis tracked the labeling patterns of protein-bound amino acids, revealing a metabolic network consisting of the glycolysis, the pentose phosphate pathway, and the tricarboxylic acid cycle with inactive glyoxylate shunt. Evidence of phosphoenolpyruvate carboxylase, phosphoenolpyruvate carboxykinase, and malic enzyme activity was also obtained. It was demonstrated that the relative activity of the pentose phosphate pathway to glycolysis under nitrogen-limited environment increased, reflecting excess NADPH requirements for lipid biosynthesis. Although the growth rate and cellular oil content were significantly altered in response to nitrogen limitation, global flux distribution of C. protothecoides remained stable, exhibiting the rigidity of central carbon metabolism. In conclusion, quantitative knowledge on the metabolic flux distribution of oleaginous alga obtained in this study may be of value in designing strategies for metabolic engineering of desirable bioproducts. PMID:20720172

  14. Gas chromatography-mass spectrometric determination of polycyclic aromatic hydrocarbons in five species of fish from three sites in the Arabian Gulf.

    PubMed

    Al-Saleh, Iman; Al-Doush, Inaam

    2002-06-01

    A gas chromatography-mass spectrmetroic (GC-MS) method was developed to measure six polycyclic aromatic hydrocarbons (PAHs) in 54 fish samples. Five fish species highly consumed by the local population (shrimps, Emperors, Rabbitfish, Doublebar Bream and Greasy Grouper) were selected from three different sites on the Gulf coast of Saudi Arabia where agricultural, municipal and petroleum industry activities take place. Variations in PAH levels among the three sites were not significant. Total concentrations of PAHs benzo(a)anthracene, chrysene, and benzo(b)fluoranthene ranged from non-detectable to 44.9 microg kg(-1). In this study, concentrations of benzo(a)anthracene, chrysene, benzo(b)fluoranthene and total PAHs greater than the acceptable tolerance limit (1 microg kg(-1)) were found in 68.5, 40.7, 51.9 and 83.3% of the fish samples, respectively. PAH contents in fish vary considerably with species; Doublebar bream contain the highest while shrimps contain the lowest. This pilot study clearly shows that the consumption of fish could be a source of exposure of the local population to PAHs. Since there is a consensus on the substantial contribution of PAHs to cancer in humans, it would be interesting to conduct further research in order to determine the magnitude of the problem along other coastal regions of Saudi Arabia. PMID:12400558

  15. Rapid determination of polycyclic aromatic hydrocarbons in grilled meat using microwave-assisted extraction and dispersive liquid-liquid microextraction coupled to gas chromatography-mass spectrometry.

    PubMed

    Kamankesh, Marzieh; Mohammadi, Abdorreza; Hosseini, Hedayat; Modarres Tehrani, Zohreh

    2015-05-01

    A simple and rapid analytical tech nique for the simultaneous determination of 16 polycyclic aromatic hydrocarbons (PAHs) in grilled meat was developed using microwave-assisted extraction and dispersive liquid-liquid microextraction (MAE-DLLME) followed by gas chromatography-mass spectrometry (GC-MS). The effective parameters in DLLME process were optimized. Good linear relationships were obtained for 16 PAHs in a range of 1-200 ng g(-1), with a correlation coefficient (R(2)) higher than 0.98. Limits of detection and limits of quantification were 0.15-0.3 ng g(-1) and 0.47-1 ng g(-1), respectively. The relative standard deviations (RSD%) for seven analyses were less than 9%. The recoveries of those compounds in grilled meat were obtained from 85% to 104%. Low consumption of the solvent, high recovery, short extraction time, no matrix interference and good merit figures compared to other methods are advantages of the proposed method. The performance of the present method was evaluated for the determination of PAHs in various types of real grilled meat samples, and satisfactory results were obtained. PMID:25618021

  16. Determination of E,E-farnesol in Makgeolli (rice wine) using dynamic headspace sampling and stir bar sorptive extraction coupled with gas chromatography-mass spectrometry.

    PubMed

    Ha, Jaeho; Wang, Yiru; Jang, Hyejin; Seog, Homoon; Chen, Xi

    2014-01-01

    In this paper, we analysed the volatile and semi-volatile compounds, including E,E-farnesol in Makgeolli which is a traditional type of Korean fermented rice wines. Forty-one compounds including alcohols, 1-butanol-3-methyl acetate, E,E-farnesol, stearol, and phytane, were separated and quantified by dynamic headspace sampling (DHS) and stir bar sorptive extraction (SBSE) coupled with gas chromatography-mass spectrometry. SBSE has been found to be an effective method for analysing E,E-farnesol levels in Makgeolli. The experimental parameters related to the extraction efficiency of the SBSE method, such as ethanol concentration and filtration, were studied and optimised. The linear dynamic range of the SBSE method for E,E-farnesol ranged from 0.02 to 200ngml(-1) with R(2)=0.9974. The limit of detection and limit of quantification of the SBSE method were 0.02 and 0.05ngml(-1), respectively. The relative standard deviation of intra- and inter-day reproducibility was less than 6.2% and 9.9%, respectively. PMID:24001815

  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. Characterization and chemical composition of fatty acids content of watermelon and muskmelon cultivars in Saudi Arabia using gas chromatography/mass spectroscopy

    PubMed Central

    Albishri, Hassan M.; Almaghrabi, Omar A.; Moussa, Tarek A. A.

    2013-01-01

    Background: The growth in the production of biodiesel, which is principally fatty acid methyl esters (FAME), has been phenomenal in the last ten years because of the general desire to cut down on the release of greenhouse gases into the atmosphere, and also as a result of the increasing cost of fossil fuels. Objective: Establish whether there is any relationship between two different species (watermelon and muskmelon) within the same family (Cucurbitaceae) on fatty acid compositions and enumerate the different fatty acids in the two species. Materials and Methods: Extraction of fatty acids from the two species and preparation the extract to gas chromatography/mass spectroscopy analysis to determine the fatty acids compositions qualitatively and quantitatively. Results: The analyzed plants (watermelon and muskmelon) contain five saturated fatty acids; tetrdecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid and octadecanoic acid with different concentrations, while muskmelon contains an extra saturated fatty acid named eicosanoic acid. The watermelon plant contains five unsaturated fatty acids while muskmelon contains three only, the two plants share in two unsaturated fatty acids named 9-hexadecenoic acid and 9-octadecenoic acid, the muskmelon plant contains higher amounts of these two acids (2.04% and 10.12%, respectively) over watermelon plant (0.88% and 0.25%, respectively). Conclusion: The chemical analysis of watermelon and muskmelon revealed that they are similar in saturated fatty acids but differ in unsaturated fatty acids which may be a criterion of differentiation between the two plants. PMID:23661995

  19. Multiwalled carbon nanotubes as matrix solid-phase dispersion extraction absorbents to determine 31 pesticides in agriculture samples by gas chromatography-mass spectrometry.

    PubMed

    Fang, Guozhen; Min, Guang; He, Jinxing; Zhang, Chao; Qian, Kun; Wang, Shuo

    2009-04-22

    A matrix solid-phase dispersion extraction (MSPDE) method was developed to extract 31 pesticides from agriculture samples using multiwalled carbon nanotubes (MWCNTs) as adsorbent prior to gas chromatography-mass spectrometry (GC-MS) determination. The comparisons of MWCNTs with C(18) and diatomite were studied in the MSPD procedure. The results showed that the extracts obtained by using MWCNTs were cleaner than those obtained by using C(18) and diatomite. Using the developed method, recoveries ranged from 74.2 to 104.2% with relative standard deviations (RSD) ranging from 3.1 to 8.8% for the apple matrix, and 71.5-113.3% with RSD ranging from 3.2 to 9.7% for the potato matrix. The limits of detection (LODs), calculated as 3 times the background noise, ranged from 0.1 to 3.1 microg kg(-1) for the apple matrix and 0.1 to 4.0 mug kg(-1) for the potato matrix. The proposed MSPDE method was used to analyze real samples obtained in a local market, the results were approximation to those obtained using accelerated solvent extraction (ASE) method, and prometryn, isocarbophos and methidathion were detected at levels below the maximum residue limits (MRLs) allowed by the Chinese Government. PMID:19326860

  20. Multi-residue determination of pesticides in water using multi-walled carbon nanotubes solid-phase extraction and gas chromatography-mass spectrometry.

    PubMed

    Wang, Shuo; Zhao, Peng; Min, Guang; Fang, Guozhen

    2007-09-21

    A reliable multi-residue method which was based on solid-phase extraction (SPE) with multi-walled carbon nanotubes (MWCNTs) as adsorbent was developed for determination and quantitation of 12 pesticides (carbofuran, iprobenfos, parathion-methyl, prometryn, fenitrothion, parathion-ethyl, isocarbofos, phenthoate, methidathion, endrin, ethion, methoxychlor) in surface water by gas chromatography-mass spectrometry (GC-MS). Parameters that might influence the extraction efficiency such as the eluent volume, the sample flow rate and the sample loading volume were optimized. The experimental results showed the excellent linearity of 12 pesticides (R(2)>0.99) over the range of 0.04-4 microg L(-1), and the precisions (RSD) were 3.1-15.1% under the optimal conditions. The detection limits of proposed method could reach 0.01-0.03 microg L(-1) based on the ratio of chromatographic signal to base line noise (S/N=3). Good recoveries achieved with spiked water samples were in the range of 82.0-103.7%. The results indicated that MWCNTs have good adsorbability to the 12 pesticides tested in this study. With less cost, less analytical time and less solvent-consuming, the developed multi-residue method could be used to determine multi-class pesticides in water simultaneously. PMID:17697685

  1. Determination of volatile components of saffron by optimised ultrasound-assisted extraction in tandem with dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry.

    PubMed

    Sereshti, Hassan; Heidari, Reza; Samadi, Soheila

    2014-01-15

    In the present research, a combined extraction method of ultrasound-assisted extraction (UAE) in conjunction with dispersive liquid-liquid microextraction (DLLME) was applied to isolation and enrichment of saffron volatiles. The extracted components of the saffron were separated and determined by gas chromatography-mass spectrometry (GC-MS) technique. The mixture of methanol/acetonitrile was chosen for the extraction of the compounds and chloroform was used at the preconcentration stage. The important parameters, such as composition of extraction solvent, volume of preconcentration solvent, ultrasonic applying time, and salt concentration were optimised by using a half-fraction factorial central composite design (CCD). Under the optimal conditions, the linear dynamic ranges (LDRs) were 10-10,000mgL(-)(1). The determination coefficients (R(2)) were from 0.9990 to 0.9997. The limits of detection (LODs) and limits of quantification (LOQs) for the extracted compounds were 6-123mgL(-)(1) and 20-406mgL(-)(1), respectively. The relative standard deviations (RSDs) were 2.48-9.82% (n=3). The enhancement factors (EFs) were 3.6-41.3. PMID:24054273

  2. Rapid determination of para-phenylenediamine by gas chromatography-mass spectrometry with selected ion monitoring in henna-containing cosmetic products.

    PubMed

    Wang, Perry G; Krynitsky, Alexander J

    2011-06-15

    A rapid method for the determination of para-phenylenediamine (PPD) in cosmetic products, such as henna tattoos has been developed and evaluated. This analytical procedure involved extracting a 10mg test portion of cosmetic product in 10 mL of ethyl acetate, followed by determination by gas chromatography-mass spectrometry in the selected ion monitoring mode (GC/MS-SIM). 1,4-Phenylenediamine-2,3,5,6-d(4) was selected as an internal standard that was added at the beginning of the extraction procedure and used to correct for recovery and matrix effects. The linearity ranged from 1.0 to 1275 ?g/mL with a coefficient of determination (r(2)) greater than 0.999. LOQ and LOD were 1.0 and 0.10 ?g/mL, respectively. The recovery in a tattoo product containing PPD was 94% and that for a tattoo product containing no PPD reached 105%. Extraction efficiency of 98% was obtained. This method has been successfully applied to henna temporary tattoo and other henna-related cosmetic products for the determination and quantitation of PPD. PMID:21606006

  3. 13C-Tracer and Gas Chromatography-Mass Spectrometry Analyses Reveal Metabolic Flux Distribution in the Oleaginous Microalga Chlorella protothecoides1[C][W][OA

    PubMed Central

    Xiong, Wei; Liu, Lixia; Wu, Chao; Yang, Chen; Wu, Qingyu

    2010-01-01

    The green alga Chlorella protothecoides has received considerable attention because it accumulates neutral triacylglycerols, commonly regarded as an ideal feedstock for biodiesel production. In order to gain a better understanding of its metabolism, tracer experiments with [U-13C]/[1-13C]glucose were performed with heterotrophic growth of C. protothecoides for identifying the metabolic network topology and estimating intracellular fluxes. Gas chromatography-mass spectrometry analysis tracked the labeling patterns of protein-bound amino acids, revealing a metabolic network consisting of the glycolysis, the pentose phosphate pathway, and the tricarboxylic acid cycle with inactive glyoxylate shunt. Evidence of phosphoenolpyruvate carboxylase, phosphoenolpyruvate carboxykinase, and malic enzyme activity was also obtained. It was demonstrated that the relative activity of the pentose phosphate pathway to glycolysis under nitrogen-limited environment increased, reflecting excess NADPH requirements for lipid biosynthesis. Although the growth rate and cellular oil content were significantly altered in response to nitrogen limitation, global flux distribution of C. protothecoides remained stable, exhibiting the rigidity of central carbon metabolism. In conclusion, quantitative knowledge on the metabolic flux distribution of oleaginous alga obtained in this study may be of value in designing strategies for metabolic engineering of desirable bioproducts. PMID:20720172

  4. An accurate method for microanalysis of carbon monoxide in putrid postmortem blood by head-space gas chromatography-mass spectrometry (HS/GC/MS).

    PubMed

    Hao, Hongxia; Zhou, Hong; Liu, Xiaopei; Zhang, Zhong; Yu, Zhongshan

    2013-06-10

    Carbon monoxide (CO) may be the cause of more than half the fatal poisonings reported in many countries, with some of these cases under-reported or misdiagnosed by medical professionals. Therefore, an accurate and reliable analytical method to measure blood carboxyhemoglobin level (COHb%), in the 1% to lethal range, is essential for correct diagnosis. Herein a method was established, i.e. head-space gas chromatography-mass spectrometry (HS/GC/MS) that has numerous advantages over other techniques, such as UV spectrometry, for determination of COHb%. There was a linear relationship (R(2)=0. 9995) between the peak area for CO and the COHb% in blood. Using a molecular sieve-packed column, CO levels in the air down to 0.01% and COHb% levels in small blood samples down to 0.2% could be quantitated rapidly and accurately. Furthermore, this method showed good reproducibility with a relative standard deviation for COHb% of <1%. Therefore, this technique provides an accurate and reliable method for determining CO and COHb% levels and may prove useful for investigation of deaths potentially related to CO exposure. PMID:23683916

  5. Optimization of headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry for detecting methoxyphenolic compounds in pu-erh tea.

    PubMed

    Du, Liping; Wang, Chao; Li, Jianxun; Xiao, Dongguang; Li, Changwen; Xu, Yongquan

    2013-01-23

    A method based on headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry was developed for the analysis of volatile methoxyphenolic compounds in pu-erh tea. Six fibers with different polarities were initially evaluated. The 75 ?m carboxen/polydimethylsiloxane fiber exhibited the highest extraction efficiency and was selected for further optimization. A Plackett-Burman design was used to screen for the brewing proportion of tea and water, amount of pu-erh tea, ionic strength, extraction time, extraction temperature, desorption time, rate of agitation, and equilibrium time. A Box-Behnken design was then applied to optimize the significant factors. Under optimal conditions, the proposed method affords a wide range of linearity, high linear regression coefficients (0.996-0.999), less than 9.0% repeatability of relative standard deviation, and limits of detection ranging from 2.31 to 21.80 ng/g. The proposed method has satisfactory accuracy, with recoveries of 79.08-113.9%. This method was successfully applied for the analysis of pu-erh tea samples. PMID:23268690

  6. Rapid Monitoring and Determination of Class 1 Residual Solvents in Pharmaceuticals Using Dispersive Liquid-Liquid Microextraction and Gas Chromatography-Mass Spectrometry.

    PubMed

    Heydari, Rouhollah; Azizi, Saber

    2015-07-01

    A simple and rapid dispersive liquid-liquid microextraction (DLLME) method coupled with gas chromatography-mass spectrometry (GC-MS) for monitoring and determination of class 1 residual solvents, benzene (Bz), carbon tetrachloride (CT), 1,2-dichloroethane (1,2-DCE), 1,1-dichloroethene (1,1-DCE), 1,1,1-trichloroethane (1,1,1-TCE), in pharmaceuticals was developed and evaluated. The parameters affecting the extraction efficiency of analytes such as type and volume of extraction solvent, type and volume of dispersive solvent and ionic strength were investigated and optimized. 1-Octanol and methanol proved to be the most suitable extraction and dispersive solvents, respectively. The method showed linearity for 1,1-DCE, 1,1,1-TCE, CT, Bz and 1,2-DCE in the ranges of 0.001-80, 0.005-80, 0.002-80, 0.0001-40 and 0.001-80 µg/mL, respectively. The relative recoveries were in the range of 84-92, 87-98, 83-94, 89-98 and 87-96% for 1,1-DCE, 1,1,1-TCE, CT, Bz and 1,2-DCE, respectively. The obtained results showed that the proposed method can be used to monitor and determine class 1 residual solvents in pharmaceuticals. PMID:25398952

  7. Contribution of oxidized tallow to aroma characteristics of beeflike process flavour assessed by gas chromatography-mass spectrometry and partial least squares regression.

    PubMed

    Song, Shiqing; Zhang, Xiaoming; Xiao, Zuobing; Niu, Yunwei; Hayat, Khizar; Eric, Karangwa

    2012-09-01

    Flavour profiles of seven beeflike process flavours (BFs) including non-oxidized or oxidized tallow were comparatively analysed by electronic nose, gas chromatography-mass spectrometry (GC-MS) and descriptive sensory analysis to characterize the headspace of BFs. Analysis of volatiles by GC-MS indicated that the effect of oxidized tallow with moderate oxidization level on Maillard reaction was more prominent than that of others, which potentially could result in an optimal meat flavour with strong, harmony and species-specific characteristics detected by sensory analysis. In addition, electronic nose data confirmed the accuracy of the GC-MS and sensory analysis results. Correlation analysis of the electronic nose measurements, sensory evaluation and characteristic compounds through Partial Least Squares Regression (PLSR) further explained that moderate oxidized tallow with peroxide value (PV) of 87.67-160 mequiv./kg, the p-anisidine value (p-AV) of 30.57-50, and the acid value (AV) of 1.8-2.2 mg KOH/g tallow was a desirable precursor for imparting aroma characteristics of beef flavour. PMID:22858364

  8. A gas chromatography-mass spectrometry method for the determination of pogostone in canine plasma and its application to a pharmacokinetic study.

    PubMed

    Zhang, Ruoqi; Peng, Cheng; Li, Yunxia; Xiong, Liang; Gong, Xiaohong

    2014-01-01

    In this study, a simple and selective gas chromatography-mass spectrometry method was developed and validated for the determination of pogostone in canine plasma. Liquid-liquid extraction was used to separate pogostone from canine plasma, and the mean extraction recovery rates of pogostone and the internal standard (isoalantolactone) were 80.61 and 75.89%, respectively. Plastic centrifuge tubes were inadequate for the plasma sample treatment procedure because of the adsorption effect of pogostone on the inner surface. The chromatographic separation was performed on a capillary column of Agilent HP-5ms, and the spectrometer was operated in an electron-impact ionization with an electron multiplier voltage mode. The standard curve was linear over the concentration range of 1.02-406 ng/mL (r > 0.99). The intra- and interday accuracies for pogostone at four concentrations were 97.77-99.92% and 98.51-100.22%, respectively. The relative standard deviations were <15%. The method was successfully applied to a pharmacokinetic study after the oral administration of pogostone to beagle dogs. PMID:24714140

  9. Headspace solid-phase microextraction gas chromatography-mass spectrometry determination of volatile compounds in different varieties of African star apple fruit (Chrysophillum albidum).

    PubMed

    Lasekan, Ola; Khatib, Alfi; Juhari, Hanisah; Patiram, Parveen; Lasekan, Seye

    2013-12-01

    The volatile compounds in four selected African star apple fruit (Chrysophyllum albidum) varieties were isolated and identified using the headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). A total of 59 compounds were identified. Application of the aroma extract dilution analysis (AEDA) to the aroma distillates from the fruits revealed 45 odour-active compounds in the flavour dilution (FD) factor range of 4-128. Among them, the highest odour activities (FD factors) were determined for methylhexanoate, acetophenone and ethyl dodecanoate. Moreover, aroma lipophilicity appears to reflect molecular conformation. Further analysis of the similarities and differences between the fruit varieties in terms of the key odourants by the application of PLS-DA and PLS-regression coefficient showed strong positive correlation between the very sweet/sweet varieties and 10 key odourants. The odourants included ethyl acetate, acetyl methyl carbinol, methylhexanoate, sabinene, p-cymene, methylbenzoate, ethylbenzoate, geraniol, cis-?-bergomotene, acetophenone, and ethyl dodecanoate. PMID:23870932

  10. Application of ethyl chloroformate derivatization for solid-phase microextraction-gas chromatography-mass spectrometric determination of bisphenol-A in water and milk samples.

    PubMed

    Mudiam, Mohana Krishna Reddy; Jain, Rajeev; Dua, Virendra K; Singh, Amit Kumar; Sharma, V P; Murthy, R C

    2011-09-01

    A simple and rapid analytical method based on in-matrix ethyl chloroformate (ECF) derivatization has been developed for the quantitative determination of bisphenol-A (BPA) in milk and water samples. The samples containing BPA were derivatised with ECF in the presence of pyridine for 20 s at room temperature, and the non-polar derivative thus formed was extracted using polydimethylsiloxane solid-phase microextraction (SPME) fibres with thicknesses of 100 ?m followed by analysis using gas chromatography-mass spectrometry. Three alkyl chloroformates (methyl, ethyl and isobutyl chloroformate) were tested for optimum derivatisation yields, and ECF has been found to be optimum for the derivatisation of BPA. Several parameters such as amount of ECF, pyridine and reaction time as well as SPME parameters were studied and optimised in the present work. The limit of detection for BPA in milk and water samples was found to be 0.1 and 0.01 ?g L(-1), respectively, with a signal-to-noise ratio of 3:1. The limit of quantitation for BPA in milk and water was found to be 0.38 and 0.052 ?g L(-1), respectively, with a signal-to-noise ratio of 10:1. In conclusion, the method developed was found to be rapid, reliable and cost-effective in comparison to silylation and highly suitable for the routine analysis of BPA by various food and environmental laboratories. PMID:21744235

  11. Validated modeling for German white wine varietal authentication based on headspace solid-phase microextraction online coupled with gas chromatography mass spectrometry fingerprinting.

    PubMed

    Springer, A E; Riedl, J; Esslinger, S; Roth, T; Glomb, M A; Fauhl-Hassek, C

    2014-07-16

    An untargeted analytical approach combined with chemometrics using the volatiles of German white wine was investigated regarding the usefulness for verifying botanical origin. A total of 198 wine samples of Riesling, Müller-Thurgau, Silvaner, Pinot Gris, and Pinot Blanc were examined applying headspace solid-phase microextraction online coupled with gas chromatography mass spectrometry. The resultant three-dimensional raw data were processed by available metabolomics software. After data treatment, a partial least-squares discriminant analysis (PLS-DA) model was validated. External samples were correctly classified for 97% Silvaner, 93% Riesling, 91% Pinot Gris/Blanc, and 80% Müller-Thurgau. This model was related to monoterpenoids, C13-norisoprenoids, and esters. Further, 100% prediction for a two-class model of Riesling versus Pinot Gris/Blanc was confirmed by 74 additional samples measured independently. Hence, the strategy applied was, in particular, reliable and relevant for white wine varietal classification. In addition, the superior classification performance of the Riesling class was revealed. PMID:25000414

  12. Development and validation of a sensitive thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) method for the determination of phosgene in air samples.

    PubMed

    Juillet, Y; Dubois, C; Bintein, F; Dissard, J; Bossée, A

    2014-08-01

    A new rapid, sensitive and reliable method was developed for the determination of phosgene in air samples using thermal desorption (TD) followed by gas chromatography-mass spectrometry (GC-MS). The method is based on a fast (10 min) active sampling of only 1 L of air onto a Tenax® GR tube doped with 0.5 mL of derivatizing mixture containing dimercaptotoluene and triethylamine in hexane solution. Validation of the TD-GC-MS method showed a low limit of detection (40 ppbv), acceptable repeatability, intermediate fidelity (relative standard deviation within 12 %) and excellent accuracy (>95%). Linearity was demonstrated for two concentration ranges (0.04 to 2.5 ppmv and 2.5 to 10 ppmv) owing to variation of derivatization recovery between low and high concentration levels. Due to its simple on-site implementation and its close similarity with recommended operating procedure (ROP) for chemical warfare agents vapour sampling, the method is particularly useful in the process of verification of the Chemical Weapons Convention. PMID:24817348

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

    PubMed

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

    2005-04-15

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

  14. Identification of volatile butyl rubber thermal-oxidative degradation products by cryofocusing gas chromatography/mass spectrometry (cryo-GC/MS).

    SciTech Connect

    Smith, Jonell Nicole; White, Michael Irvin; Bernstein, Robert; Hochrein, James Michael

    2013-02-01

    Chemical structure and physical properties of materials, such as polymers, can be altered as aging progresses, which may result in a material that is ineffective for its envisioned intent. Butyl rubber formulations, starting material, and additives were aged under thermal-oxidative conditions for up to 413 total days at up to 124 %C2%B0C. Samples included: two formulations developed at Kansas City Plant (KCP) (%236 and %2310), one commercially available formulation (%2321), Laxness bromobutyl 2030 starting material, and two additives (polyethylene AC-617 and Vanax MBM). The low-molecular weight volatile thermal-oxidative degradation products that collected in the headspace over the samples were preconcentrated, separated, and detected using cryofocusing gas chromatography mass spectrometry (cryo-GC/MS). The majority of identified degradation species were alkanes, alkenes, alcohols, ketones, and aldehydes. Observations for Butyl %2310 aged in an oxygen-18 enriched atmosphere (18O2) were used to verify when the source of oxygen in the applicable degradation products was from the gaseous environment rather than the polymeric mixture. For comparison purposes, Butyl %2310 was also aged under non-oxidative thermal conditions using an argon atmosphere.

  15. Determination of Wastewater Compounds in Whole Water by Continuous Liquid-Liquid Extraction and Capillary-Column Gas Chromatography/Mass Spectrometry

    USGS Publications Warehouse

    Zaugg, Steven D.; Smith, Steven G.; Schroeder, Michael P.

    2006-01-01

    A method for the determination of 69 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 on aquatic organisms in wastewater. This method also is useful for evaluating the effects of combined sanitary and storm-sewer overflow on the water quality of urban streams. The method focuses on the determination of compounds that are indicators of wastewater or have endocrine-disrupting potential. These compounds include the alkylphenol ethoxylate nonionic surfactants, food additives, fragrances, antioxidants, flame retardants, plasticizers, industrial solvents, disinfectants, fecal sterols, polycyclic aromatic hydrocarbons, and high-use domestic pesticides. Wastewater compounds in whole-water samples were extracted using continuous liquid-liquid extractors and methylene chloride solvent, and then determined by capillary-column gas chromatography/mass spectrometry. Recoveries in reagent-water samples fortified at 0.5 microgram per liter averaged 72 percent ? 8 percent relative standard deviation. The concentration of 21 compounds is always reported as estimated because method recovery was less than 60 percent, variability was greater than 25 percent relative standard deviation, or standard reference compounds were prepared from technical mixtures. Initial method detection limits averaged 0.18 microgram per liter. Samples were preserved by adding 60 grams of sodium chloride and stored at 4 degrees Celsius. The laboratory established a sample holding-time limit prior to sample extraction of 14 days from the date of collection.

  16. Concurrent quantification of light and heavy sulphur volatiles in wine by headspace solid-phase microextraction coupled with gas chromatography/mass spectrometry.

    PubMed

    Fedrizzi, Bruno; Magno, Franco; Moser, Sergio; Nicolini, Giorgio; Versini, Giuseppe

    2007-01-01

    A new method based on headspace solid-phase microextraction coupled with gas chromatography/mass spectrometry (HS-SPME-GC/MS) to analyse 13 light and heavy volatile sulphur compounds in the same run was established. For the successful application of the procedure, various adsorption process parameters were optimised. In particular the nature of the adsorptive phase, the temperature, the ionic strength of the sample solutions and the equilibration time were considered. The best extraction conditions, in terms of the maximum signal obtainable for each compound, were obtained with a carboxen-polydimethylsiloxane-divinylbenzene (CAR-PDMS-DVB) 2 cm long coating fibre. The choice of suitable internal standards and the matrix effect were studied and the proposed method was validated by determining linearity, precision and accuracy, evaluating the critical, detection and quantification limits. This method is fast, sensitive and precise and easy to transfer to wine quality control. Finally, the proposed method was applied to the determination of the aforementioned sulphur compounds in 32 red and white wines. PMID:17279596

  17. Determination of the herbicide glyphosate and its metabolite in biological specimens by gas chromatography-mass spectrometry. A case of poisoning by roundup herbicide.

    PubMed

    Hori, Yasushi; Fujisawa, Manami; Shimada, Kenji; Hirose, Yasuo

    2003-04-01

    In Japan, poisonings by the glyphosate (GLYP)-containing herbicide Roundup and the gluphosinate (GLUF)-based herbicide BASTA have been increasing since about 1987. We applied the gas chromatography-mass spectrometry (GC-MS) method of analysis, on which we have already reported in regard to the determination of the blood serum level of GLUF and its metabolite, for the determination of serum and urinary levels of GLYP and its metabolite aminomethyl phosphonic acid (AMPA). Derivatization using N-methyl-N-(tert-butyldimethylsilyl) trifluoroacetamide was completed at a temperature of 80 degrees C after 30 min, and the detection limit of GLYP was 10 pg using m/z 454 and that of AMPA was 1 pg using m/z 396. The full mass spectra of 100 pg GLYP and of 10 pg AMPA were obtained easily. In extractions for which the Isolute HAX cartridge was employed, the mean recovery rate of GLYP and AMPA added to serum to yield concentrations of 10-0.1 microg/mL (n = 5) was 91.6 +/- 10.6% (or better), whereas that of GLYP and AMPA added to urine to yield concentrations of 100-1.0 microg/mL (n = 10) was 93.3 +/- 6.6% (or better), both of which were good rates. Also, using this method of analysis, the presence of GLYP was identified in the full mass spectra obtained from the serum of a patient who may or may not have ingested Roundup. PMID:12731658

  18. A rapid assay for the simultaneous determination of nicotine, cocaine and metabolites in meconium using disposable pipette extraction and gas chromatography-mass spectrometry (GC-MS).

    PubMed

    Mozaner Bordin, Dayanne C; Alves, Marcela N R; Cabrices, Oscar G; de Campos, Eduardo G; De Martinis, Bruno Spinosa

    2014-01-01

    Drug abuse by pregnant women is considered a serious public health problem worldwide. Meconium is the first excretion in newborns and has been used as an alternative matrix to evaluate in utero drug exposure. Solid phase extraction (SPE) is widely employed to prepare and clean up samples in the field of forensic analysis. Most SPE products require large volumes of solvent, which culminates in longer sample processing times and increased cost per sample. Disposable pipette extraction (DPX) tips have been used as an alternative to traditional SPE cartridges. They combine efficient and rapid extraction with reduced solvent consumption. The purpose of this study was to develop and validate a method to determine nicotine, cotinine, cocaine, benzoylecgonine, cocaethylene and methyl ester anhydroecgonine in meconium using DPX and gas chromatography-mass spectrometry (GC-MS). Validation results indicated that extraction efficiency ranged 50-98%, accuracy 92-106%, intra-assay precision 4-12% and inter-assay precision 6-12%. Linear calibration curves resulted in R(2) values >0.99, limits of detection ranged from 2.5 to 15 ng/g and the limit of quantitation from 10 to 20 ng/g. The DPX-GC-MS method was shown to selectively analyze trace concentrations of drugs in meconium samples. Finally, the developed and validated method was applied to 50 meconium samples. PMID:24272386

  19. Determination of eight pharmaceuticals in an aqueous sample using automated derivatization solid-phase microextraction combined with gas chromatography-mass spectrometry.

    PubMed

    Huang, Siming; Zhu, Fang; Jiang, Ruifen; Zhou, Shichun; Zhu, Derong; Liu, Hong; Ouyang, Gangfeng

    2015-05-01

    An automated aqueous derivatization solid-phase microextraction (SPME) coupled with a gas chromatography/mass spectrometry (GC/MS) method was developed for simultaneous determination of eight pharmaceuticals in water samples. Dimethyl sulfate and tetrabutylammonium hydrogen sulfate were selected as derivatization and activation reagents for the esterification reaction. An experimental design approach, central composition design (CCD), was employed to investigate and optimize the operative factors influencing the extraction efficiency, including extraction time, extraction temperature and ionic strength. The other parameters such as type of fiber coating, pH and derivatization conditions were also evaluated. SPME was finally carried out in headspace mode at 80°C for 60min with the presence of 3.00g Na2SO4, using a home-made 44?m PDMS fiber. Wide linear ranges and low limits of detection (0.06-1.24ng L(-1)) were obtained under the optimized conditions. The relative standard deviations (RSDs) and recoveries ranged from 0.5% to 12.3% and 85% to 110%, respectively. The proposed method was successfully applied to the analysis of the real surface water samples from the Pearl River Estuary. PMID:25703003

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2013-01-01

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

  2. Sensitive and robotic determination of bromate in sea water and drinking deep-sea water by headspace solid-phase micro extraction and gas chromatography-mass spectrometry.

    PubMed

    Lim, Hyun-Hee; Shin, Ho-Sang

    2012-09-01

    A robotic method has been established for the determination of bromate in sea water and drinking deep-sea water. Bromate in water was converted into volatile derivative, which was measured with headspace solid-phase micro extraction and gas chromatography-mass spectrometry (HS-SPME GC-MS). Derivatization reagent and the HS-SPME parameters (selection of fibre, extraction/derivatization temperature, heating time and; the morality of HCl) were optimized and selected. Under the established conditions, the detection and the quantification limits were 0.016 ?g L(-1) and 0.051 ?g L(-1), respectively, and the intra- and inter-day relative standard deviation was less than 7% at concentrations of 1.0 and 10.0 ?g L(-1). The calibration curve showed good linearity with r(2)=0.9998. The common ions Cl(-), NO(3)(-), SO(4)(2-), HPO(4)(2-), H(2)PO(4)(-), K(+), Na(+), NH(4)(+), Ca(2+), Mg(2+), Ba(2+), Mn(4+), Mn(2+), Fe(3+) and Fe(2+) did not interfere even when present in 1000-fold excess over the active species. The method was successfully applied to the determination of bromate in sea water and drinking deep-sea water. PMID:22840702

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

    PubMed

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

    2010-04-01

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

  4. Determination of additives in cosmetics by supercritical fluid extraction on-line headspace solid-phase microextraction combined with gas chromatography-mass spectrometry.

    PubMed

    Yang, Tzung-Jie; Tsai, Feng-Jie; Chen, Chung-Yu; Yang, Thomas Ching-Cherng; Lee, Maw-Rong

    2010-06-01

    A new hyphenated technique couples supercritical fluid extraction in situ derivatization and on-line headspace solid-phase microextraction to gas chromatography-mass spectrometry (SFE in situ derivatization on-line HS-SPME-GC-MS) for the determination of paraben preservatives and polyphenolic antioxidants in cosmetics. The preservatives and antioxidants were extracted from the cosmetic matrices with supercritical carbon dioxide at a pressure of 13,840 kPa. The supercritical fluid extraction was performed at 55 degrees C for 10 min of static extraction then 15 min of dynamic extraction. The extractant subsequently was derivatized in situ with the silylation reagent N,O-bis(trimethylsilyl)trifluoroacetamide with 0.1% trimethylchlorosilane. The product was then adsorbed on a polyacrylate solid-phase microextraction (SPME) fiber in the headspace. Sea sand was used as a dispersive material in the SFE step. The analytical linear ranges for the preservatives and antioxidants were found to be from 10 to 1000 ng g(-1) with RSD values below 7.8%. The detection limits ranged from 0.5 to 8.3 ng g(-1). These results are better than those obtained by using only SPME or SFE for trace preservatives and antioxidants analysis in cosmetic matrices. The new method was successfully utilized to determine the amounts of preservatives and antioxidants in real cosmetics without the need for tedious pretreatments. PMID:20493297

  5. Determination of malondialdehyde in human blood by headspace-solid phase micro-extraction gas chromatography-mass spectrometry after derivatization with 2,2,2-trifluoroethylhydrazine.

    PubMed

    Shin, Ho-Sang

    2009-11-01

    Malondialdehyde (MDA) has been proposed as a useful biomarker of lipoperoxidation in biological samples, and more developed analytical methods are necessary. A simple and sensitive gas chromatography-mass spectrometry (HS-SPME-GC-MS) was described for the determination of malondialdehyde (MDA) in blood. Acetone-d(6) was used as internal standard. MDA and acetone d6 in blood reacted for 40 min at 50 degrees C with 2,2,2-trifluoroethylhydrazine in headspace vial and simultaneously the formed TFEH derivatives were vaporized and adsorbed on polydimethylsiloxane-divinylbenzene (PDMS-DVB). The compounds were desorbed for 1 min at 240 degrees C and injected in GC-MS. The reaction solution showed good recoveries at pH 4.0. In the established condition, the method detection limit (MDL) was 0.4 microg/L in 0.1 mL blood sample and the relative standard deviation was less than 8% at the concentration of 25.0 and 50.0 microg/L. The mean concentrations of MDA in normal human blood (n=20) were measured to be 187.9 microg/L (2.61 micromol/L). PMID:19800854

  6. Headspace solid-phase microextraction with on-fiber derivatization for the determination of aldehydes in algae by gas chromatography-mass spectrometry.

    PubMed

    Ma, Jiping; Xiao, Ronghui; Li, Jinhua; Li, Jie; Shi, Benzhang; Liang, Yanjuan; Lu, Wenhui; Chen, Lingxin

    2011-06-01

    A simple, fast, sensitive and cost-effective method based on headspace solid-phase microextraction (HS-SPME) with on-fiber derivatization coupled with gas chromatography-mass spectrometry was developed for the determination of six typical aldehydes, 2E-hexenal, heptanal, 2E-heptenal, 2E,4E-heptadienal, 2E-decenal and 2E,4E-decadienal in laboratory algae cultures. As derivatization reagent, O-2,3,4,5,6-(pentafluorobenzyl) hydroxylamine hydrochloride, was loaded onto the poly(dimethylsiloxane)/divinylbenzene fiber for aldehydes on-fiber derivatization prior to HS-SPME. Various influence factors of extraction efficiency were systematically investigated. Under optimized extraction conditions, excellent method performances for all the six aldehydes were attained, such as satisfactory extraction recoveries ranging from 67.1 to 117%, with the precision (relative standard deviation) within 5.3-11.1%, and low detection limits in the range of 0.026-0.044 ?g/L. The validated method was successfully applied for the analysis of the aldehydes in two diatoms (Skeletonema costatum and Chaetoceros muelleri), two pyrrophytas (Prorocentrum micans and Scrippsiella trochoidea) and Calanus sinicus eggs (feeding on the two diatoms above). PMID:21567947

  7. Headspace generation coupled to gas chromatography-mass spectrometry for the automated determination and quantification of endogenous compounds in urine. Aldehydes as possible markers of oxidative stress.

    PubMed

    Antón, Ana Pérez; Ferreira, Ana María Casas; Pinto, Carmelo García; Cordero, Bernardo Moreno; Pavón, José Luis Pérez

    2014-11-01

    A methodology for the determination of five aldehydes in urine has been developed based on the coupling of a headspace generation sampler with a gas chromatography-mass spectrometry system equipped with a programmed temperature vaporizer. This instrumental configuration minimizes sample manipulation and allows the determination of these compounds without the need for a derivatization step so that the methodology is largely shortened and simplified. An experimental design was carried out in order to optimize the headspace sampling. Sample matrix effect was eliminated by means of dilution of urine samples. The calibration models displayed good linearity (0.1-10 ?g/L) and their validity was checked using ANOVA, and it was observed that they did not exhibit any lack of fit. The LODs obtained ranged between 0.04 and 0.08 ?g/L and the LOQs between 0.12 and 0.24 ?g/L. The accuracy of the method was evaluated in terms of apparent recoveries which were between 86 and 120%. The method developed was applied to the analysis of 17 samples of urine from different subjects in order to quantify these endogenous compounds. PMID:25280875

  8. Determination of aromatic amines in human urine using comprehensive multi-dimensional gas chromatography mass spectrometry (GCxGC-qMS).

    PubMed

    Lamani, Xolelwa; Horst, Simeon; Zimmermann, Thomas; Schmidt, Torsten C

    2015-01-01

    Aromatic amines are an important class of harmful components of cigarette smoke. Nevertheless, only few of them have been reported to occur in urine, which raises questions on the fate of these compounds in the human body. Here we report on the results of a new analytical method, in situ derivatization solid phase microextraction (SPME) multi-dimensional gas chromatography mass spectrometry (GCxGC-qMS), that allows for a comprehensive fingerprint analysis of the substance class in complex matrices. Due to the high polarity of amino compounds, the complex urine matrix and prevalence of conjugated anilines, pretreatment steps such as acidic hydrolysis, liquid-liquid extraction (LLE), and derivatization of amines to their corresponding aromatic iodine compounds are necessary. Prior to detection, the derivatives were enriched by headspace SPME with the extraction efficiency of the SPME fiber ranging between 65 % and 85 %. The measurements were carried out in full scan mode with conservatively estimated limits of detection (LOD) in the range of several ng/L and relative standard deviation (RSD) less than 20 %. More than 150 aromatic amines have been identified in the urine of a smoking person, including alkylated and halogenated amines as well as substituted naphthylamines. Also in the urine of a non-smoker, a number of aromatic amines have been identified, which suggests that the detection of biomarkers in urine samples using a more comprehensive analysis as detailed in this report may be essential to complement the approach of the use of classic biomarkers. PMID:25142049

  9. Simple and automatic determination of aldehydes and acetone in water by headspace solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Kim, Hyun-Ji; Shin, Ho-Sang

    2011-03-01

    We describe a simple and automatic method to determine nine aldehydes and acetone simultaneously in water. This method is based on derivatization with 2,2,2-trifluoroethylhydrazine (TFEH) and consecutive headspace-solid-phase microextraction and gas chromatography-mass spectrometry. Acetone-d(6) was used as the internal standard. Aldehydes and acetone in water reacted for 30 min at 40°C with TFEH in a headspace vial and the formed TFEH derivatives were simultaneously vaporized and adsorbed on polydimethylsiloxane-divinylbenzene. Under the established condition, the method detection limit was 0.1-0.5 ?g/L in 4 mL water and the relative standard deviation was less than 13% at concentrations of 0.25 and 0.05 mg/L. This method was applied to determine aldehydes and acetone in 5 mineral water and 114 surface water samples. All mineral water samples had detectable levels of methanal (24.0-61.8 ?g/L), ethanal (57.7-110.9 ?g/L), propanal (11.5-11.7 ?g/L), butanal, pentanal (3.3-3.4 ?g/L) and nonanal (0.3-0.4 ?g/L). Methanal and ethanal were also detected in concentration range of 2.7-117.2 and 1.2-11.9 ?g/L, respectively, in surface water of 114 monitoring sites in Korea. PMID:21319300

  10. In situ derivatization reaction and determination of ibuprofen in water samples using headspace generation-programmed temperature vaporization-gas chromatography-mass spectrometry.

    PubMed

    Pérez Pavón, José Luis; Casas Ferreira, Ana María; Fernández Laespada, María Esther; Moreno Cordero, Bernardo

    2009-09-25

    The aim of the present work is to propose a method for the determination of ibuprofen, as a typical representative of pharmaceutical compounds, in aqueous samples. To do so, an in situ derivatization reaction in aqueous medium was employed in the vial of a headspace sampler (HS), after which instrumental measurements were made with gas chromatography-mass spectrometry (GC-MS). As the injection system we propose a programmed temperature vaporizer (PTV) where, in solvent vent mode, better results can be obtained than with the conventional split and splitless injection modes. Since the derivatization reaction takes place in the HS vial, after the mixing of reagents and the sealing of the vial, the whole process takes place on-line, with no need for intermediate steps. The simplicity and speed of the method--analysis throughput: 10.5 min--together with the limit of detection obtained (0.23 microg/L), bearing in mind that no preconcentration step or later clean-up step are required, make this a good method for the analysis of ibuprofen in aqueous samples of urban waste water. PMID:19700164

  11. Up-and-down-shaker-assisted dispersive liquid-liquid microextraction coupled with gas chromatography-mass spectrometry for the determination of fungicides in wine.

    PubMed

    Chu, Shang-Ping; Tseng, Wan-Chi; Kong, Po-Hsin; Huang, Chun-Kai; Chen, Jung-Hsuan; Chen, Pai-Shan; Huang, Shang-Da

    2015-10-15

    An up-and-down-shaker-assisted dispersive liquid-liquid microextraction (UDSA-DLLME) method coupled with gas chromatography-mass spectrometry was developed for the determination of fungicides (cyprodinil, procymidone, fludioxonil, flusilazole, benalaxyl, and tebuconazole) in wine. The developed method requires 11?L of 1-octanol without the need for dispersive solvents. The total extraction time was approximately 3min. Under optimum conditions, the linear range of the method was 0.05-100?gL(-1) for all fungicides and the limit of detection was 0.007-0.025?gL(-1). The absolute and relative recoveries were 31-83% and 83-107% for white wine, respectively, and 32-85% and 83-108% for red wine, respectively. The intra-day and inter-day precision were 0.5-7.5% and 0.7-6.1%, respectively. Our developed method had good sensitivity and high extraction efficiency. UDSA-DLLME is a desirable method in terms of performance and speed. PMID:25952882

  12. Optimization and comparison of three methods for extraction of volatile compounds from Cyperus rotundus evaluated by gas chromatography-mass spectrometry.

    PubMed

    Tam, C U; Yang, F Q; Zhang, Q W; Guan, J; Li, S P

    2007-06-28

    The essential oil of Cyperus rotundus has multiple pharmacological activities. Therefore, the extraction with high yield and quality is very important for preparation of essential oil of C. rotundus. In this paper, three methods, namely hydrodistillation (HD), pressurized liquid extraction (PLE) and supercritical fluid extraction (SFE), for extraction of volatile compounds from C. rotundus were optimized and compared by gas chromatography-mass spectrometry. Among eight identified compounds in C. rotundus, five components including alpha-copaene, cyperene, beta-selinene, beta-cyperone and alpha-cyperone were quantitatively determined or estimated using alpha-cyperone as standard, which showed that PLE had the highest extraction efficiency, while SFE had the best selectivity for extraction of beta-cyperone and alpha-cyperone. The contents of ingredients from C. rotundus extracted with HD, PLE and SFE are significantly different, which suggest that comparison of chemical components and pharmacological activities of different extracts is helpful to elucidate the active components in C. rotundus and control its quality. PMID:17127024

  13. Separation and determination of ephedrine alkaloids and tetramethylpyrazine in Ephedra sinica Stapf by gas chromatography-mass spectrometry.

    PubMed

    Li, H X; Ding, M Y; Lv, K; Yu, J Y

    2001-09-01

    A simple, sensitive, and reliable method using gas chromatography (GC)-mass spectrometry (MS) is developed for the simultaneous determination of ephedrine alkaloids and 2,3,5,6-tetramethylpyrazine (TMP) in Ephedra sinica Stapf. The sample is extracted with ethyl ether and submitted to GC-MS for identification and quantitation without derivatization. The column used for GC is an HP-5 (30.0 m x 250 microm x 0.25 microm, 5% phenyl methyl siloxane), and the carrier gas is helium. The detection limits for ephedrine, pseudoephedrine, and TMP are 0.4 ng 0.7 ng, and 0.02 ng (signal-to-noise ratio of 3), respectively. The reproducibility of the total procedure is proved to be acceptable (RSD < 2%), and the recoveries are above 93%. PMID:11565946

  14. Rapid determination of DDT and related compounds in soils via carbon skeleton gas chromatography-mass spectrometry.

    PubMed

    Cooke, M; Khallef, K D; Nickless, G; Roberts, D J

    1979-10-19

    The levels of DDT and related compounds in soil samples from an apple orchard have been determined. Extraction of residues was achieved by cyclic steam extraction and by conventional solvent extraction methods allowing comparison of the two methods. Determination of the organochlorine residues present in the extracts was performed by gas-liquid chromatography-electron-capture detection and by carbon skeleton gas chromatograph-mass spectrometry. Excellent agreement between the two determination techniques was achieved. Prior to application of p,p'-DDT, a value of approximately 0.4 ppm was obtained for Delta DDT in the soil. The major component of this total was DDE. After spraying the apple trees with technical grade, p,p'-DDT, Delta DDT for the soil rose to 0.6 ppm. This increase was due to translocation of p,p'-DDT from the trees. PMID:528650

  15. Isotope dilution determination of polycyclic aromatic hydrocarbons in olive pomace oil by gas chromatography–mass spectrometry

    Microsoft Academic Search

    Gianfranco Diletti; Giampiero Scortichini; Rossana Scarpone; Giuseppe Gatti; Luigi Torreti; Giacomo Migliorati

    2005-01-01

    A gas chromatographic (GC) method with mass spectrometry detection (MS) for the determination of eight polycyclic aromatic hydrocarbons (PAHs) in olive pomace oil has been developed. The oil was diluted with n-pentane and extracted by liquid–liquid partition with dimethyl sulphoxide (DMSO). After water addition and back-extraction with cyclohexane, a thin-layer chromatography on silica gel was performed as a further purification

  16. TagFinder for the quantitative analysis of gas chromatography - mass spectrometry (GC-MS)-based metabolite profiling experiments

    Microsoft Academic Search

    Alexander Lüdemann; Katrin Strassburg; Alexander Erban; Joachim Kopka

    2008-01-01

    Motivation: Typical GC-MS-based metabolite profiling experiments may comprise hundreds of chromatogram files, which each contain up to 1000 mass spectral tags (MSTs). MSTs are the characteristic patterns of 25-250 fragment ions and respective isotopomers, which are generated after gas chromatography (GC) by electron impact ionization (EI) of the separated chemical molecules. These fragment ions are subsequently detected by time-of-flight (TOF)

  17. GC-MS in the analysis of organic compounds in meteorites. [Gas Chromatography-Mass Spectroscopy approaches

    NASA Technical Reports Server (NTRS)

    Lawless, J. G.; Romiez, M. P.

    1974-01-01

    The application of an analytical approach combining gas chromatography with mass spectrometry (GC-MS) has shown that the amino acid composition of meteorite extracts is quite complex. A computer was used in the evaluation of the data obtained in the investigations. The computer programs developed have been concerned solely with the mass spectra of amino acids. Specialized programs have been written to determine the number of carbon atoms in an amino acid which is a member of any of three subclasses.

  18. Determination of endogenous and synthetic glucocorticoids in human urine by gas chromatography–mass spectrometry following microwave-assisted derivatization

    Microsoft Academic Search

    Luca Amendola; Flaminia Garribba; Francesco Botrè

    2003-01-01

    A complete screening and confirmation analytical method for the direct determination of six endogenous (cortisol, cortisone, deoxycorticosterone, tetrahydrocortisol, tetrahydrocortisone, tetrahydro-S) and 17 synthetic (amcinonide, betamethasone, desoximethasone, dexamethasone, fludrocortisone, flumethasone, flunisolide, flucinolone acetonide, flucinonide, fluprednisolone, flurandrenolide, fluorometholone, 6-methylprednisolone, prednisolone, prednisone, triamcinolone, triamcinolone acetonide) glucocorticoids in human urine by gas chromatography with mass spectrometric detection (GC–MS) is presented.The analytical technique comprises a

  19. 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

  20. Development and application of compact denuder sampling techniques with in situ derivatization followed by gas chromatography-mass spectrometry for halogen speciation in volcanic plumes

    NASA Astrophysics Data System (ADS)

    Rüdiger, Julian; Bobrowski, Nicole; Hoffmann, Thorsten

    2015-04-01

    Volcanoes are a large source for several reactive atmospheric trace gases including sulphur and halogen containing species. The detailed knowledge of volcanic plume chemistry can give insights into subsurface processes and can be considered as a useful geochemical tool for monitoring of volcanic activity, especially halogen to sulphur ratios (e.g. Bobrowski and Giuffrida, 2012; Donovan et al., 2014). The reactive bromine species bromine monoxide (BrO) is of particular interest, because BrO as well as SO2 are readily measurable by UV spectrometers at a safe distance. Furthermore it is formed in the plume by a multiphase reaction mechanism under depletion of ozone in the plume. The abundance of BrO changes as a function of the reaction time and therefore distance from the vent as well as the spatial position in the plume. Due to the lack of analytical approaches for the accurate speciation of certain halogens (HBr, Br2, Br, BrCl, HOBr etc.) there are still uncertainties about the magnitude of volcanic halogen emissions and in particular their specificationtheir species and therefore also in the understanding of the bromine chemistry in volcanic plumes (Bobrowski et al., 2007). In this study, the first application of a 1,3,5-trimethoxybenzene (1,3,5-TMB)-coated gas diffusion denuder (Huang and Hoffmann, 2008) on volcanic gases proved to be suitable to collect selectively gaseous bromine species with oxidation states of +1 or 0 (Br2 and BrO(H)), while being ignorant to HBr (OS -1). The reaction of 1,3,5-TMB with bromine gives 1-bromo-2,4,6-trimethoxybenzene (1-bromo-2,4,6-TMB) - other halogens give corresponding products. The diffusion denuder technique allows sampling of gaseous compounds exclusively without collecting particulate matter. Choosing a flow rate of 500 mL-min-1 and a denuder length of 0.5 m a nearly quantitative collection efficiency was achieved. Solvent elution of the derivatized analytes and subsequent analysis with gas chromatography-mass spectrometry gives a limit of detection below 1 ng of bromine. The method was applied on volcanic gas plumes at Mt. Etna and Mt. Stromboli in Italy in July 2014 and on fumarolic gas emissions at Mt. Lastarria in Chile in November 2014. The results show significant amounts of the concerning bromine species (lower ppb range). Comprehensive data evaluation and comparison with results of impinger extraction with NaOH solution as well as chamber experiments are still in progress. References Bobrowski, N. and G. Giuffrida: Bromine monoxide / sulphur dioxide ratios in relation to volcanological observations at Mt. Etna 2006-2009. Solid Earth, 3, 433-445, 2012 Bobrowski, N., R. von Glasow, A. Aiuppa, S. Inguaggiato, I. Louban, O. W. Ibrahim and U. Platt: Reactive halogen chemistry in volcanic plumes. J. Geophys. Res., 112, 2007 Donovan A., V. Tsanev, C. Oppenheimer and M. Edmonds: Reactive halogens (BrO and OClO) detected in the plume of Soufrière Hills Volcano during an eruption hiatus. Geochem. Geophys. Geosyst., 15, 3346-3363, 2014 Huang, R.-J. and T. Hoffmann: A denuder-impinger system with in situ derivatization followed by gas chromatography-mass spectrometry for the determination of gaseous iodine-containing halogen species. Journal of Chromatography A, 1210, 135-141, 2008

  1. Hydrocarbons identified in extracts from estuarine water accommodated no. 2 fuel oil by gas chromatography-mass spectrometry

    NASA Technical Reports Server (NTRS)

    Lewis, B. W.; Walker, A. L.; Bieri, R. H.

    1974-01-01

    Results are presented on a computerized gas chromatograph-mass spectrometer analysis of methylene chloride and n-heptane extracts of a No. 2 fuel oil accommodated estuarine water sample. The analytical method is briefly described, and the limitations on the identifications are categorized. Some attempt was made to determine major and trace constituents in the water accommodate. Altogether 66 hydrocarbon compounds were identified specifically, and 75 compounds were partially identified. Seven compounds could be recognized as major constituents of the water accommodated oil and ten were present only as traces. The aromatic compounds found were alkyl benzenes, naphthalene, tetralin, indane, biphenyl, fluorene, anthracene, and some of their alkyl substituted isomers in the range of carbon numbers C7 to C15. Four n-alkanes, C10 to C13, were found along with four other assorted hydrocarbons.

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

    PubMed

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

    2014-02-01

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

  3. [Characterization of aroma active compounds in blood orange juice by solid phase microextraction and gas chromatography-mass spectrometry-olfactometry].

    PubMed

    Qiao, Yu; Xie, Bijun; Zhang, Yan; Zhang, Yun; Pan, Siyi

    2008-07-01

    Volatile compounds of fresh blood orange juice were analyzed by solid phase microextraction and gas chromatography-mass spectrometry (SPME-GC-MS) and the aroma active compounds were identified by olfactometry. The volatile compounds were extracted by headspace solid phase microextraction (HS-SPME) using a divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber for 40 min at 40 degrees C. The analysis was carried out using an HP 6890N GC equipped with an HP-5 column (30 m x 0.25 mm x 0.25 microm ) directly connected to an HP 5975 series mass selective detector and a sniffing port (ODP2, Gerstel) using helium as carrier gas. Compound identifications were made by the comparison of the mass spectra, retention times, retention indices (I(R)) and odor of the volatile components in the extracts with those of the corresponding reference standards. Forty-six compounds were identified by GC-MS and I(R). The major components of the juice were limonene (86.36%), linalool (3.69%), beta-myrcene (1.79%), octanal (1.32%) and valencene (1.27%). GC-MS-olfactometry analysis was performed to determine 34 compounds with aroma activity, of which 23 compounds were identified. The major contributors to orange juice aroma activity are ethyl butanoate, octanal, gamma-terpinene, 4-acetyl-1-methyleyclohexene, decanal, (-)-carvone, geranyl acetate, valencene. These compounds of strong aroma intensity represent 7.22% of the total volatile compounds. Other four unknown compounds (I(R), <800; I(R) = 1020, 1143, 1169, separately) are also the major contributors to the overall aroma. PMID:18959252

  4. Microemulsion mediated in situ derivatization-extraction and gas chromatography-mass spectrometric analysis of alkylphosphonic acids.

    PubMed

    Pardasani, Deepak; Palit, Meehir; Gupta, A K; Kanaujia, Pankaj K; Sekhar, K; Dubey, D K

    2006-03-10

    Detection and identification of environmental signatures of chemical warfare agents is an important aspect of verification program of Chemical Weapons Convention (CWC). Alkylphosphonic acids (APAs) are ultimate and persistent degradation products of nerve agents. Their identification in a sample submitted for off-site analysis infers possible indication of contamination with nerve agents. This paper describes the development of a new sample preparation method which involves 'in situ derivatization and extraction' (INDEX) of acids from water. Derivatization is performed by alkylation of APAs with alkylbromides in surfactant less microemulsion (SLME). The derivatized analytes were analyzed by gas chromatography coupled with mass spectrometry. The developed method involves simultaneous derivatization (alkylation) and extraction of acidic analytes mediated by surfactant less microemulsion. Various derivatization-extraction parameters such as solvent, reaction time and temperature, base and alkyl bromides were optimized. Pentyl bromide in the presence of potassium carbonate and diisopropylamine at 100 degrees C derivatized the selected acids efficiently. Kinetic data for alkylation of methylphosphonic acids and some carboxylic acids were obtained to assess their relative susceptibility for alkylation in microemulsion. Methylphosphonic acid and isopropyl methylphosphonic acid took 140-150 min to reach completion while carboxylic acids took 100 min to complete the reaction. INDEX could be successfully performed even in the presence of interfering Ca(2+) and Mg(2+) ions. PMID:16455095

  5. Determination of Tuta absoluta pheromones in water and tomato samples by headspace-gas chromatography-mass spectrometry.

    PubMed

    del Carmen Alcudia-León, María; Lucena, Rafael; Cárdenas, Soledad; Valcárcel, Miguel

    2015-01-01

    Tuta absoluta is a tomato pest which is originally from South America. This pest was detected in eastern Spain in 2006 and it rapidly invaded various European countries and spread throughout the Mediterranean basin. The usual detection of this pest is based on the physical evaluation of the crops and in the exhaustive count of potential insects in dedicated traps. The early detection of that pest on the basis of more objective or measurable indicators is desirable. In this case, the combination of headspace and gas chromatography with mass spectrometric detection is proposed for the identification of Tuta absoluta pest using two of its pheromone components as markers. These components, namely: (3E,8Z,11Z)-tetradecatrien-1-yl acetate and (3E,8Z)-tetradecadien-1-yl acetate, are characteristic of Tuta absoluta and they are not present in other insect pheromones. The developed combination allows the determination of both components in water and tomato samples with limits of detection in the range from 25-32 ng/L to 89-111 ng/kg, respectively. The precision, expressed as relative standard deviation, was better than 4.6% for water samples and better than 7.1% when tomato samples were analyzed. The relative recovery values varied in the interval 94-100 and 83-99% for water and tomato samples. PMID:24928116

  6. Development of a new method for the determination of thyroxine in serum based on isotope dilution gas chromatography mass spectrometry.

    PubMed

    Thienpont, L M; De Brabandere, V I; Stöckl, D; De Leenheer, A P

    1994-08-01

    A new gas chromatographic/mass spectrometric method in combination with isotope dilution for the determination of thyroxine in serum is described. Special attention was paid to the methylation step of thyroxine, which was investigated using methanolic HCl, dimethylformamide/dimethylacetal and diazomethane, the latter giving the best results in terms of reproducible isotope ratios. For internal standardization, (13C6)-thyroxine was dissolved in fraction V human albumin solution (70 g l-1). The internal standard-in-albumin solution was mixed with known amounts of thyroxine standard, dissolved in 0.05 M Na2HPO4 buffer at pH 11.6, to give isotope ratios of 0.75, 1.00 and 1.25. The same internal standard solution was also used for isotope dilution of the unknown serum samples. The volume of serum was adapted to give a 1:1 isotope ratio. Sample pretreatment consisted of protein precipitation and a two-step liquid/liquid extraction procedure. After methylation of unlabelled and labelled thyroxine with diazomethane and perfluoroacylation with pentafluoropropionic anhydride and heptafluorobutyric anhydride, respectively, mass spectrometric monitoring was done at m/z 951/957 and 1001/1007. Quantitative determination of thyroxine in five serum samples in duplicate, during three consecutive days, showed a mean overall imprecision of 1.0% and a deviation of +0.4% from the target value as determined by a definitive method. PMID:7918690

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

    PubMed

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

    2014-06-01

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

  8. Multiresidue determination of pesticides in juice by solid-phase extraction and gas chromatography-mass spectrometry.

    PubMed

    Albero, Beatriz; Sánchez-Brunete, Consuelo; Tadeo, José L

    2005-05-15

    A multiresidue method based on solid-phase extraction was developed for the simultaneous determination of 50 pesticides in commercial juices. The extraction procedure was carried out in C(18) columns preconditioned with acetonitrile and water. The subsequent elution of pesticides was performed with a mixture of hexane-ethyl acetate (1:1, v/v) prior to the determination by gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode (GC-MS-SIM), using one target and two qualifier ions. Standards were prepared spiking blank juice samples to counteract the observed matrix effect. Average recoveries for all the pesticides studied were higher than 91% with relative standard deviations lower than 9% in the concentration range of 0.02-0.1mug/mL and the detection limits achieved ranged from 0.1 to 4.6mug/L. The proposed method was applied to the analysis of these compounds in commercial juices and diazinon, ethion and procymidone were the pesticides encountered, although the levels found were very low. PMID:18970072

  9. Determination of organochlorine pesticides in sewage sludge by matrix solid-phase dispersion and gas chromatography-mass spectrometry.

    PubMed

    Sánchez-Brunete, Consuelo; Miguel, Esther; Tadeo, José L

    2008-02-15

    A method based on matrix solid-phase dispersion (MSPD) has been developed for the determination of 16 organochlorine pesticides (OCs) in sludge from municipal sewage plants. Samples of lyophilized sludge were blended with alumina, placed in small columns and OCs extracted with dichloromethane assisted by sonication. Purification of the extracts was accomplished by solid-phase extraction on C(18) columns and OCs were eluted with acetonitrile. Analyses were performed by gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode (GC-MS-SIM) using deuterated OCs as internal standards. The limits of detection were between 0.03 ng/g for 4,4'-DDE and 0.7 ng/g for endrin aldehyde. Levels of OCs were determined in sewage sludge collected from 19 water treatment plants located in the province of Madrid (Spain). In all of the analyzed samples, aldrin was the compound most often found with a mean concentration of 76 ng/g. Endosulfan-I, alpha-BHC, 4,4'-DDE and 4,4'-DDT were also present at high concentrations, with average values ranging from 32.3 to 74.3 ng/g. OCs were detected in all of the samples, with a total concentration ranging from 52 to 528 ng/g dry weight. PMID:18371771

  10. [Determination of ethyl glucuronide in human urine by solid phase extraction-gas chromatography-mass spectrometry].

    PubMed

    Yu, Tianxiao; Li, Qing; Wan, Tao; Li, Jianbo; Ding, Shijia

    2011-02-01

    A solid phase extraction (SPE) and gas chromatography (GC) with mass spectrometry (MS) method for determination of ethyl glucuronide (EtG) in human urine was established. One mL urine sample was deproteinated by 100 microL 3 mol/L hydrochloric acid and cleaned up through a solid phase extraction column. The target analytes were eluted from an NH2-column with 4% ammonia solution and then treated with bis (trimethylsilyl) trifluoroacetamide (BSTFA) + trimethylchlorosilane (TMCS) (99:1) for derivatization. The derivatized samples were analyzed by GC-MS. Data were acquired in the selected ion monitoring (SIM) mode and the quantitation of EtG was done through internal standard method. Good linearity was obtained at the mass concentration range of 0.1 - 3.2 mg/L with a correlation coefficient (r) of 0.9921. The limit of detection (LOD) was 28.4 microg/L. The range of recoveries was 92.5% - 108.7%, and the relative standard deviations (RSDs) of intra-day and inter-day were all less than 5%. This method is sensitive, specific, accurate and can be applied to the determination of EtG for medicolegal identification and clinical laboratory. PMID:21598520

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

    PubMed

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

    2010-10-22

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

  12. Effects of co-existed proteins on measurement of pesticide residues in blood by gas chromatography-mass spectrometry.

    PubMed

    Yue, Yingxia; Li, Lun; Liang, Yong; Dong, Linjie; Dong, Qingjian; Zhong, Hongying

    2010-11-15

    Accurate measurement of pesticides in biological fluids such as blood is important for quantifying environmental exposures. Beyond sample enrichment and separation, the method presented here is focused on studies of interactions between pesticides and co-existed proteins. It was experimentally demonstrated that entrapped or adsorbed pesticide residues within the folded native structures of proteins were poorly recovered using direct solvent extraction solely. We described here an effective approach termed Enzymatic Digestion-Organic Solvent Extraction (eDOSE) that utilizes the enzymatic approach to disrupt the folded structures of proteins and release entrapped or adsorbed pesticide residues. In this approach, samples were first reduced, alkylated, tryptically digested and then diluted 10 times before the subsequent extraction using an n-hexane solution. Resultant pesticide residues were determined by capillary gas chromatography coupled with a mass spectrometer. Mean recoveries of the 5 organophosphorus pesticides pre-spiked in fish blood including diazinon, parathion-methyl, malathion, parathion-ethyl and ethion were 85%, 95%, 84%, 103%, and 43% respectively using eDOSE strategy but only 24%, 45%, 40%, 27%, and 29% respectively using direct solvent extraction approach. The eDOSE approach was effective for demonstrating the critical role of folded native structure of serum albumin in adsorption of exogenous chemicals. It provides an alterative means for denaturation of proteins when the target analytes are not stable in acidic solution or entrapped within the protein aggregates caused by organic solvents such as acetone that have been applied for protein denaturation. The eDOSE approach should be able to combine with other advanced techniques of enrichment and separation for more efficient and accurate measurement of target compounds present in the context of complex biological systems. This approach can provide wide applications to the analysis of a variety of small molecules including environmental pesticide residues and metabolites as well as other toxins present in cells, tissues and biofluids. PMID:20970391

  13. Analysis of cigarette mainstream smoke for 1,1-dimethylhydrazine and vinyl acetate by gas chromatography-mass spectrometry.

    PubMed

    Diekmann, J; Biefel, C; Rustemeier, K

    2002-10-01

    1,1-Dimethylhydrazine, also known as unsymdimethylhydrazine (UDMH) and vinyl acetate (VA), are both classified by the International Agency for Research on Cancer as 2B carcinogens (possibly carcinogenic to humans) and listed as cigarette smoke constituents; however, there is little or no quantitative data available on them. For UDMH in cigarette smoke, neither a yield nor a method has been published. For VA, the most recent information on yields dates back to 1965. To bridge this gap, we have developed new gas chromatographic-mass spectrometric methods for both compounds to determine their yields in cigarette smoke. UDMH is determined by derivatization with 2-nitrobenzaldehyde in methanol and is not found in cigarette smoke at levels above the detection limit of 19 ng/cig. In further experiments, when UDMH is added to the smoke stream or air stream of lit or unlit cigarettes, the derivative 2-nitrobenzaldehyde-2,2-dimethylhydrazone is found only in the air stream of the unlit cigarettes. From this, we conclude that UDMH is either not formed during smoking at all or, if it is, it reacts immediately and quantitatively with other smoke constituents (e.g., aldehydes) and is therefore not detectable in cigarette smoke. VA is determined by trapping in acetone at -78 degrees C and is found at a concentration of 270 ng/cig for a standard reference cigarette with a cellulose acetate filter (the reference cigarette 1 R4F). In the literature, VA is reported at concentrations of 1.6 microg/cig for a cigarette with a cellulose acetate/charcoal filter and 4 microg/cig for a cigarette with a cellulose acetate filter and for an unfiltered cigarette. PMID:12433113

  14. Detection of Mycobacterium tuberculosis in Sputum by Gas Chromatography-Mass Spectrometry of Methyl Mycocerosates Released by Thermochemolysis

    PubMed Central

    O'Sullivan, Denise M.; Nicoara, Simona C.; Mutetwa, Reggie; Mungofa, Stanley; Lee, Oona Y-C.; Minnikin, David E.; Bardwell, Max W.; Corbett, Elizabeth L.; McNerney, Ruth; Morgan, Geraint H.

    2012-01-01

    Tuberculosis requires rapid diagnosis to prevent further transmission and allow prompt administration of treatment. Current methods for diagnosing pulmonary tuberculosis lack sensitivity are expensive or are extremely slow. The identification of lipids using gas chromatography- electron impact mass spectrometry (GC-EI/MS) could provide an alternative solution. We have studied mycocerosic acid components of the phthiocerol dimycocerosate (PDIM) family of lipids using thermochemolysis GC-EI/MS. To facilitate use of the technology in a routine diagnostic laboratory a simple extraction procedure was employed where PDIMs were extracted from sputum using petroleum ether, a solvent of low polarity. We also investigated a method using methanolic tetramethylammonium hydroxide, which facilitates direct transesterification of acidic components to methyl esters in the inlet of the GC-MS system. This eliminates conventional chemical manipulations allowing rapid and convenient analysis of samples. When applied to an initial set of 40 sputum samples, interpretable results were obtained for 35 samples with a sensitivity relative to culture of 94% (95%CI: 69.2,100) and a specificity of 100% (95%CI: 78.1,100). However, blinded testing of a larger set of 395 sputum samples found the assay to have a sensitivity of 61.3% (95%CI: 54.9,67.3) and a specificity of 70.6% (95%CI: 62.3,77.8) when compared to culture. Using the results obtained we developed an improved set of classification criteria, which when applied in a blinded re-analysis increased the sensitivity and specificity of the assay to 64.9% (95%CI: 58.6,70.8) and 76.2% (95%CI: 68.2,82.8) respectively. Highly variable levels of background signal were observed from individual sputum samples that inhibited interpretation of the data. The diagnostic potential of using thermochemolytic GC-EI/MS of PDIM biomarkers for diagnosis of tuberculosis in sputum has been established; however, further refinements in sample processing are required to enhance the sensitivity and robustness of the test. PMID:22403716

  15. Multiclass determination of 66 organic micropollutants in environmental water samples by fast gas chromatography-mass spectrometry.

    PubMed

    Cherta, Laura; Beltran, Joaquim; Portolés, Tania; Hernández, Félix

    2012-03-01

    A multiresidue method has been developed for quantification and identification of 66 multiclass priority organic pollutants in water by fast gas chromatography (GC) coupled to mass spectrometry (MS). Capabilities and limitations of single quadrupole mass spectrometer as detector in fast GC were studied evaluating the chromatographic responses in terms of sensitivity and chromatographic peak shapes, as they were influenced by scan time. The number of monitored ions in a selected ion monitoring (SIM) group strongly conditioned the scan time and subsequently the number of data points per peak. A compromise between peak shape and scan time was adopted in order to reach the proper conditions for quantitative analysis. An average of 10-15 points per peak was attained for most compounds, involving scan times between 0.1 and 0.22 s. The method was validated for mineral, surface, and groundwater. A solid-phase extraction pre-concentration step using C(18) cartridges was applied. Four isotopically labeled standards were added to the samples before extraction and used as surrogates to ensure a reliable quantification. Analyses were performed by GC-MS in electron ionization mode, monitoring the three most abundant and/or specific ions for each compound and using the intensity ratios as a confirmatory parameter. With a chromatographic run of less than 10 min, SIM mode provided excellent sensitivity and identification capability due to the monitoring of three ions and the evaluation of their intensity ratio. Limits of detection below 10 ng/L were reached for most of the 66 compounds in the three matrices studied. Accuracy and precision of the method were evaluated by means of recovery experiments at two fortification levels (10 and 100 ng/L), obtaining recoveries between 70% and 120% in most cases and relative standard deviations below 20%. The possibilities of a simultaneous SIM scan method have also been explored for non-target qualitative analysis. The developed method has been applied to the analysis of surface water samples collected from the Mediterranean region of Spain. PMID:21956264

  16. Isotope dilution determination of polycyclic aromatic hydrocarbons in olive pomace oil by gas chromatography-mass spectrometry.

    PubMed

    Diletti, Gianfranco; Scortichini, Giampiero; Scarpone, Rossana; Gatti, Giuseppe; Torreti, Luigi; Migliorati, Giacomo

    2005-01-14

    A gas chromatographic (GC) method with mass spectrometry detection (MS) for the determination of eight polycyclic aromatic hydrocarbons (PAHs) in olive pomace oil has been developed. The oil was diluted with n-pentane and extracted by liquid-liquid partition with dimethyl sulphoxide (DMSO). After water addition and back-extraction with cyclohexane, a thin-layer chromatography on silica gel was performed as a further purification step. The PAHs spot was scraped off from the plate and the final extract was concentrated and analysed by GC-MS in full scan mode. The eight PAHs under investigation were determined in the presence of the corresponding labelled compounds added as internal standards to the sample at the beginning of the analytical process. The identified PAHs were then quantified by the isotope dilution methodology assuring the compensation of the concentration of each analyte for any variation in the sample preparation. The method precision was satisfactory with relative standard deviation (R.S.D.) values in the range 3.6-12.7% for all PAHs. The average recovery rates ranged from 69.0 to 97.5%. Accuracy was also calculated for benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene and benzo[ghi]perylene by analysing a certified reference material (CRM 458, coconut oil) with adequate results. All response curves exhibited a linear fit from 0.1 to 10 microg ml(-1) and the determination coefficients R2 were better than 0.9942. The limits of detection (0.1-0.4 microg kg(-1)) were acceptable when compared with the maximum permitted limit of 2 microg kg(-1) for each of the eight considered PAHs and 5 microg kg(-1) for the sum of the eight PAHs established by the Italian legislation. Measurement uncertainty was finally calculated identifying and quantifying the uncertainty components of the analytical process. The relative expanded uncertainties (Uc), expressed as percent values were in the range 8.5-11.4% thus appropriate for residues quantification in the range of concentrations considered in the present study. PMID:15679162

  17. Investigation of Volatile Compounds in Two Raspberry Cultivars by Two Headspace Techniques: SolidPhase Microextraction\\/Gas Chromatography-Mass Spectrometry (SPME\\/GC-MS) and Proton-Transfer Reaction-Mass Spectrometry (PTR-MS)

    Microsoft Academic Search

    Eugenio Aprea; Franco Biasioli; Silvia Carlin; Isabella Endrizzi; Flavia Gasperi

    2009-01-01

    The volatile compounds emitted by two raspberry varieties {(Rubus} idaeus, cv. Polka and Tulameen) were analyzed, in both the case of fresh fruits and juices, by two headspace methods that are rapid, solvent-free, and with reduced or no sample pretreatment: solid-phase microextraction\\/gas chromatography-mass spectrometry {(SPME\\/GC-MS)} and proton-transfer reaction-mass spectrometry {(PTR-MS).} Multivariate analysis of the {SPME\\/GC-MS} results allows for an unambiguous

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

    Microsoft Academic Search

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

    2007-01-01

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

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

    PubMed

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

    2013-09-13

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

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

    PubMed

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

    2013-06-01

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

  1. 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

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

    PubMed Central

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

    2007-01-01

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

  3. Dispersive solid-phase extraction based on oleic acid-coated magnetic nanoparticles followed by gas chromatography-mass spectrometry for UV-filter determination in water samples.

    PubMed

    Román, Iván P; Chisvert, Alberto; Canals, Antonio

    2011-05-01

    A sensitive analytical method to concentrate and determine extensively used UV filters in cosmetic products at (ultra)trace levels in water samples is presented. The method is based on a sample treatment using dispersive solid-phase extraction (dSPE) with laboratory-made chemisorbed oleic acid-coated cobalt ferrite (CoFe(2)O(4)@oleic acid) magnetic nanoparticles (MNPs) as optimized sorbent for the target analytes. The variables involved in dSPE were studied and optimized in terms of sensitivity, and the optimum conditions were: mass of sorbent, 100mg; donor phase volume, 75 mL; pH, 3; and sodium chloride concentration, 30% (w/v). After dSPE, the MNPs were eluted twice with 1.5 mL of hexane, and then the eluates were evaporated to dryness and reconstituted with 50 ?L of N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) for the injection into the gas chromatography-mass spectrometry (GC-MS). Under the optimized experimental conditions the method provided good levels of repeatability with relative standard deviations below 16% (n=5, at 100 ng L(-1) level). Limit of detection values ranged between 0.2 and 6.0 ng L(-1), due to the high enrichment factors achieved (i.e., 453-748). Finally, the proposed method was applied to the analysis of water samples of different origin (tap, river and sea). Recovery values showed that the matrices under consideration do not significantly affect the extraction process. PMID:21411104

  4. Characterization of volatile organic compounds and odorants associated with swine barn particulate matter using solid-phase microextraction and gas chromatography-mass spectrometry-olfactometry.

    PubMed

    Cai, Lingshuang; Koziel, Jacek A; Lo, Yin-Cheung; Hoff, Steven J

    2006-01-13

    Swine operations can affect air quality by emissions of odor, volatile organic compounds (VOCs) and other gases, and particulate matter (PM). Particulate matter has been proposed to be an important pathway for carrying odor. However, little is known about the odor-VOCs-PM interactions. In this research, continuous PM sampling was conducted simultaneously with three collocated TEOM 1400a analyzers inside a 1000-head swine finish barn located in central Iowa. Each TEOM was fitted with total suspended particulate (TSP), PM-10, PM-2.5 and PM-1 preseparators. Used filters were stored in 40 mL vials and transported to the laboratory. VOCs adsorbed/absorbed to dust were allowed to equilibrate with vial headspace. Solid-phase microextraction (SPME) Carboxen/polydimethylsiloxane (PDMS) 85 microm fibers were used to extract VOCs. Simultaneous chemical and olfactometry analyses of VOCs and odor associated with swine PM were completed using a gas chromatography-mass spectrometry-olfactometry (GC-MS-O) system. Fifty VOCs categorized into nine chemical function groups were identified and confirmed with standards. Five of them are classified as hazardous air pollutants. VOCs were characterized with a wide range of molecular weight, boiling points, vapor pressures, water solubilities, odor detection thresholds, and atmospheric reactivities. All characteristic swine VOCs and odorants were present in PM and their abundance was proportional to PM size. However, the majority of VOCs and characteristic swine odorants were preferentially bound to smaller-size PM. The findings indicate that a significant fraction of swine odor can be carried by PM. Research of the effects of PM control on swine odor mitigation is warranted. PMID:16297922

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

    PubMed

    Schött, Hans-Frieder; Lütjohann, Dieter

    2015-07-01

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

  6. Automated pipeline for classifying Aroclors in soil by gas chromatography/mass spectrometry using modulo compressed two-way data objects.

    PubMed

    Zhang, Mengliang; Harrington, Peter de B

    2013-12-15

    Seven polychlorinated biphenyls (PCBs) commercial mixtures, Aroclor 1016, 1221, 1232, 1242, 1248, 1254, and 1260, were analyzed by gas chromatography/mass spectrometry (GC/MS) combined with solid phase microextraction (SPME). Three pattern recognition methods: a fuzzy rule-building expert system (FuRES), partial least-squares discriminant analysis (PLS-DA), and a fuzzy optimal associative memory (FOAM) were used to build classification models. Modulo compression was introduced for data preprocessing to extract the characteristic features and compress the data size. Baseline correction and data normalization were also applied prior to data processing. Four GC/MS data set configurations were constructed and used to evaluate the classifiers and data pretreatments including two-way modulo compressed, two-way data, one-way total ion current and one-way total mass spectrum. The results indicate that modulo compression and baseline correction methods significantly improved the performance of the classifiers which resulted in improved classification rates for FuRES, PLS-DA, and FOAM classifiers. By using two-way modulo compressed data sets, the average classification rates with FuRES, PLS-DA, and FOAM were 100±0%, 94.6±0.7%, and 96.1±0.6% for 100 bootstrapped Latin partitions of the Aroclor standards. The classifiers were validated by application to Aroclor samples extracted from soil with no parametric changes except that the calibration set of standards and validation set of soil samples were individually mean centered. The classification rates for the GC/MS modulo 35 compressed data obtained from the Aroclor soil samples with FOAM, FuRES, and PLS-DA were 100%, 96.4%, and 78.6%, respectively. Therefore, a chemometric pipeline for SPME-GC/MS data coupled with chemometric analysis was devised as a fast authentication method for different Aroclors in soil. PMID:24209371

  7. Determination of sevoflurane and isopropyl alcohol in exhaled breath by thermal desorption gas chromatography-mass spectrometry for exposure assessment of hospital staff.

    PubMed

    Ghimenti, Silvia; Tabucchi, Sara; Bellagambi, Francesca G; Lomonaco, Tommaso; Onor, Massimo; Trivella, Maria Giovanna; Fuoco, Roger; Di Francesco, Fabio

    2015-03-15

    Volatile anaesthetics and disinfection chemicals pose ubiquitous inhalation and dermal exposure risks in hospital and clinic environments. This work demonstrates specific non-invasive breath biomonitoring methodology for assessing staff exposures to sevoflurane (SEV) anaesthetic, documenting its metabolite hexafluoroisopropanol (HFIP) and measuring exposures to isopropanol (IPA) dermal disinfection fluid. Methods are based on breath sample collection in Nalophan bags, followed by an aliquot transfer to adsorption tube, and subsequent analysis by thermal desorption gas chromatography-mass spectrometry (TD-GC-MS). Ambient levels of IPA were also monitored. These methods could be generalized to other common volatile chemicals found in medical environments. Calibration curves were linear (r(2)=0.999) in the investigated ranges: 0.01-1000 ppbv for SEV, 0.02-1700 ppbv for IPA, and 0.001-0.1 ppbv for HFIP. The instrumental detection limit was 10 pptv for IPA and 5 pptv for SEV, both estimated by extracted ion-TIC chromatograms, whereas the HFIP minimum detectable concentration was 0.5 pptv as estimated in SIM acquisition mode. The methods were applied to hospital staff working in operating rooms and clinics for blood draws. SEV and HFIP were present in all subjects at concentrations in the range of 0.7-18, and 0.002-0.024 ppbv for SEV and HFIP respectively. Correlation between IPA ambient air and breath concentration confirmed the inhalation pathway of exposure (r=0.95, p<0.001) and breath-borne IPA was measured as high as 1500 ppbv. The methodology is easy to implement and valuable for screening exposures to common hospital chemicals. Although the overall exposures documented were generally below levels of health concern in this limited study, outliers were observed that indicate potential for acute exposures. PMID:25619625

  8. Optimization of ultrasonic-assisted extraction for determination of polycyclic aromatic hydrocarbons in biochar-based fertilizer by gas chromatography-mass spectrometry.

    PubMed

    Chen, Ping; Sun, Mingxing; Zhu, Zhixiu; Zhang, Jidong; Shen, Guoqing

    2015-08-01

    Application of biochar-based fertilizers is increasingly being considered for its potential agronomic and environmental benefits. However, biochar may contain residues of polycyclic aromatic hydrocarbons (PAHs) as a result of its production by pyrolysis. The strong adsorption of PAHs to biochar makes extraction and analysis of biochar-based fertilizers difficult. This study optimizes the extraction of PAHs in biochar-based fertilizer samples by using an ultrasonic bath for quantification by gas chromatography-mass spectrometry. Among 12 solvents, acetone-cyclohexane (1:1) mixture was selected as the optimum solvent for extraction. Three variables affecting the extraction were studied by Box-Behnken design. The optimum conditions were 57 °C extraction temperature, 81 min extraction time, and two extraction cycles, which were validated by assessing the linearity of analysis, LOD, LOQ, recovery, and levels of PAHs in real biochar-based fertilizer samples. Results revealed that the 16 U.S. EPA PAHs had good linearity, with squared correlation coefficients greater than 0.99. LODs were low, ranging from 2.2 ng g(-1) (acenaphthene) to 23.55 ng g(-1) (indeno[1,2,3-cd]perylene), and LOQs varied from 7.51 ng g(-1) to 78.49 ng g(-1). The recoveries of 16 individual PAHs from the three biochar-based fertilizer samples were 81.8-109.4 %. Graphical Abstract Use of RSM to optimize UAE for extraction of the PAHs in biochar-based fertilizer. PMID:26048058

  9. [Determination of 34 pesticide residues in rice, proso millet and wheat with QuEChERS-on line gel permeation chromatography-gas chromatography-mass spectrometry].

    PubMed

    Ruan, Hua; Rong, Weiguang; Ma, Yongjian; Ji, Wenlian; Liu, Hualiang; Song, Ninghui

    2013-12-01

    A method for the simultaneous determination of 34 pesticides in rice, proso millet and wheat by QuEChERS coupled with on line gel permeation chromatography-gas chromatography-mass spectrometry (GPC-GC-MS) was developed. The effects of the sample weight, extraction solvent, sorbent for purification were investigated. The matrix effect and the usefulness of analyte protectant were also studied. The identification and quantification were performed by GPC-GC-MS in selected ion monitoring (SIM) mode and exrternal standard method. The calibration curves of the 34 pesticides showed good linearity in th range of 0.0125-0.2 mg/L with thea correlations coefficients (r2) between 0.968 and 0.999. The average recoveries were 94.5%-117.1%, 83.1%-121.7% and 93.1%-120.2% with the relative standard deviations (RSDs, n = 6) no more than 14.5%, 15.1% and 15.2% in rice, proso millet and wheat samples, respectively. The LODs of this method were 0.0281-5.31, 0.0282-4.82 and 0.0273 -5.13 microg/kg (S/N = 3) for rice, proso millet and wheat samples, respectively. The low cost and less consumption of reagents of this method are in accordance with the concept of green chemistry. The convenient operation and versatility of this method are suitable for the fast screening and detection of the 34 pesticide residues in rice, proso millet and wheat. PMID:24669714

  10. Determination of five booster biocides in seawater by stir bar sorptive extraction-thermal desorption-gas chromatography-mass spectrometry.

    PubMed

    Giráldez, I; Chaguaceda, E; Bujalance, M; Morales, E

    2013-01-01

    Stir bar sorptive extraction (SBSE) and thermal desorption (TD)-gas chromatography-mass spectrometry (GC-MS) have been optimized for the determination of five organic booster biocides (Chlorothalonil, Dichlofluanid, Sea-Nine 211, Irgarol 1051 and TCMTB) in seawater samples. The parameters affecting the desorption and absorption steps were investigated using 10 mL seawater samples. The optimised conditions consisted of an addition of 0.2 g mL(-1) KCl to the sample, which was extracted with 10mm length, 0.5mm film thickness stir bars coated with polydimethylsiloxane (PDMS), and stirred at 900 rpm for 90 min at room temperature (25 °C) in a vial. Desorption was carried out at 280 °C for 5 min under 50 mL min(-1) of helium flow in the splitless mode while maintaining a cryotrapping temperature of 20 °C in the programmed-temperature vaporization (PTV) injector of the GC-MS system. Finally, the PTV injector was ramped to a temperature of 280 °C and the analytes were separated in the GC and detected by MS using the selected-ion monitoring (SIM) mode. The detection limits of booster biocides were found to be in the range of 0.005-0.9 ?g L(-1). The regression coefficients were higher than 0.999 for all analytes. The average recovery was higher than 72% (R.S.D.: 7-15%). All these figures of merit were established running samples in triplicate. This simple, accurate, sensitive and selective analytical method may be used for the determination of trace amounts of booster biocides in water samples from marinas. PMID:23246091

  11. [Extraction of triazine herbicides from environmental water samples with magnetic graphene nanoparticles as the adsorbent followed by determination using gas chromatography-mass spectrometry].

    PubMed

    Zhang, Guijiang; Zang, Xiaohuan; Zhou, Xin; Wang, Lu; Wang, Chun; Wang, Zhi

    2013-11-01

    A novel method was developed for the determination of seven triazine herbicides in environmental water samples by magnetic solid-phase extraction with graphene-based magnetic nanoparticles (G-Fe3O4 MNPs) as the adsorbent coupled with gas chromatography-mass spectrometry detection. The main factors influencing the extraction efficiency including the amount of G-Fe3O4, the extraction time, the pH and the ionic strength of sample solution and the desorption conditions were optimized. Under the optimized experimental conditions, the enrichment factors of the method for the analytes were in the range from 574 to 968; the linearities of the method ranged from 0.01 to 10.0 microg/L for simazine, propazine, metribuzin, simetryn and cyanazine, from 0.05 to 10.0 microg/L for atrazine and from 0.01 to 8.0 microg/L for prometryn, with the correlation coefficients (r) ranging from 0.996 8 to 0.999 8. The limits of detection were in the range between 1.0 and 5.0 ng/L. Good reproducibilities were obtained with the relative standard deviations below 10.5%. The developed method was applied to the analysis of the triazine herbicides in different water samples (lake, well and tap). The recoveries of the method were in the range from 79.8% to 118.3% at the spiked levels of 0.5 microg/L and 2.0 microg/L. The results indicated that the developed method can be used as a simple and efficient technique for the determination of the triazine herbicides in environmental water samples. PMID:24558842

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

    PubMed

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

    2010-12-24

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

  13. Quantitative determination of some volatile suspected allergens in cosmetic creams spread on skin by direct contact sorptive tape extraction-gas chromatography-mass spectrometry.

    PubMed

    Sgorbini, B; Ruosi, M R; Cordero, C; Liberto, E; Rubiolo, P; Bicchi, C

    2010-04-16

    This study describes a method based on direct contact sorptive tape extraction followed by on-line thermal desorption gas chromatography-mass spectrometry (DC-STE-GC-MS) to detect and quantify a group of suspected volatile allergens on the European Union (E.U.) list and a related compound on the skin (the stratum corneum) of volunteers treated with a cream of known composition fortified with the reference allergens. The following compounds were tested: citronellol, Z-citral (neral), geraniol, cinnamaldehyde, anisyl alcohol, cinnamyl alcohol, eugenol, methyleugenol, coumarin, isoeugenol, alpha-isomethylionone, 2-(4-tert-butylbenzyl)propionaldehyde (lilial), alpha-amylcinnamaldehyde, alpha-hexylcinnamaldehyde. Sorptive tape extraction (STE) is a sorption-based sampling technique in which a flexible polydimethylsiloxane (PDMS) tape is used to recover analytes by direct contact with the surface of a solid matrix or from the headspace in equilibrium with it. The reliability of the method was confirmed by: (i) allergen recoveries varying from 52.3% for lilial to 95.7% for neral, (ii) linearity in the range 10-150ppm, with regression coefficient R(2) always above 0.97, (iii) repeatability of each analyte, RSD% never exceeding 10%, (iv) intermediate precision, always below 15%, and (v) LOD and LOQ in the ppb range, therefore fully compatible with E.U. prescriptions (ppm). Other parameters such as substantivity analyte, approximate permeation through skin and influence of different nature of stratum corneum on recovery were also investigated. The method was also successfully applied to five commercially available creams declared to contain some of the allergens in question spread on the skin of the same volunteers. PMID:20074740

  14. 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

  15. [Investigation of the pyrolysis behavior of 4-oxo-beta-damascone by on-line pyrolysis gas chromatography-mass spectrometry].

    PubMed

    Wu, Yiqin; Yang, Liu; Liu, Fang; Miao, Mingming; Zhu, Hongyou; Mao, Deshou

    2007-05-01

    The pyrolysis behavior of an essence, 4-oxo-beta-damascone, was investigated using an on-line pyrolysis gas chromatography-mass spectrometry (PyGC/MS). In helium atmosphere, the compound was pyrolyzed at 350, 450, 550, 650, 700, and 750 degrees C, separately. The pyrolysis products were directly introduced into GC/MS with 1.03 x 10(6) Pa He and were qualitatively and semi-quantitatively analyzed. At the six pyrolysis temperatures mentioned above, 3, 7, 15, 33, 42 and 45 products were detected and their relative contents were 96.25%, 85.44%, 87.18%, 78.37%, 78.29% and 83.13%, respectively. The results indicated that the pyrolysis temperature directly affected the pyrolysis pattern and the relative content of the products. A total of 54 products were identified, including beta-damascone, 4-oxo-beta-ionone, 3,4,4-trimethyl-2-cyclohex-en-1-one and 2,5,5-trimethyl-cyclohex-3-en-1-one. At 550 degrees C, only a small portion of the parent compound was pyrolyzed. At 750 degrees C, the compound was completely pyrolyzed, with a conversion of 99.74% and 45 products were given. Moreover, with the elevation of the pyrolysis temperature, complex pyrolysis products were formed, and harmful substances, such as benzene, toluene, anthracene and phenanthrene were identified. According to the relative content and the category of the pyrolysis products, the pyrolysis mechanism of 4-oxo-beta-damascone is further discussed with the conclusion that the pyrolysis of this compound might take place via 4 different pathways. The investigation gave an exemplification for the transfer behavior of tobacco essence in the cigarette burning process, and provided a reliable theoretical foundation for the perfume reinforcement technology in tobacco products, contributing to the development of cigarette products with better aroma and taste. PMID:17679441

  16. An automated headspace solid-phasemicroextraction followed by gas chromatography–mass spectrometry method to determine macrocyclic musk fragrances in wastewater samples.

    PubMed

    Vallecillos, Laura; Borrull, Francesc; Pocurull, Eva

    2013-11-01

    A fully automated method has been developed for determining eight macrocyclic musk fragrances in wastewater samples. The method is based on headspace solid-phase microextraction (HS-SPME) followed by gas chromatography–mass spectrometry (GC-MS). Five different fibres (PDMS 7 ?m, PDMS 30 ?m, PDMS 100 ?m, PDMS/DVB 65 ?m and PA 85 ?m) were tested. The best conditions were achieved when a PDMS/DVB 65 ?m fibre was exposed for 45 min in the headspace of 10 mL water samples at 100 °C. Method detection limits were found in the low ng L?1 range between 0.75 and 5 ng L?1 depending on the target analytes. Moreover, under optimized conditions, the method gave good levels of intra-day and inter-day repeatabilities in wastewater samples with relative standard deviations (n =5, 1,000 ng L?1) less than 9 and 14 %, respectively. The applicability of the method was tested with influent and effluent urban wastewater samples from different wastewater treatment plants (WWTPs). The analysis of influent urban wastewater revealed the presence of most of the target macrocyclic musks with, most notably, the maximum concentration of ambrettolide being obtained in WWTP A (4.36 ?g L?1) and WWTP B (12.29 ?g L?1), respectively. The analysis of effluent urban wastewater showed a decrease in target analyte concentrations, with exaltone and ambrettolide being the most abundant compounds with concentrations varying between below method quantification limit (

  17. Determination of hormones in milk by hollow fiber-based stirring extraction bar liquid-liquid microextraction gas chromatography mass spectrometry.

    PubMed

    Xu, Xu; Liang, Fanghui; Shi, Jiayuan; Zhao, Xin; Liu, Zhuang; Wu, Lijie; Song, Ying; Zhang, Hanqi; Wang, Ziming

    2013-08-01

    The hollow fiber-based stirring extraction bar liquid-liquid microextraction was applied to the extraction of hormones, including 17-?-ethinylestradiol, 17-?-estradiol, estriol, 17-?-estradiol, estrone, 17-?-hydroxyprogesterone, medroxyprogesterone, progesterone and norethisterone acetate, in milk. The present method has the advantages of both hollow fiber-liquid phase microextraction and stirring bar sorptive extraction. The stirring extraction bar was used as both the stirring bar of microextraction, and extractor of the analytes, which can make extraction, clean-up and concentration be carried out in one step. When the extraction was completed, the stirring extraction bar was easy isolated from the extraction system with the magnet. Several experimental parameters, including the type of extraction solvent, the number of hollow stirring extraction bar, extraction time, stirring speed, ionic strength, and desorption conditions were investigated and optimized. The analytes in the extract were derived and determined by gas chromatography mass spectrometry. Under optimal experimental conditions, good linearity was observed in the range of 0.20-20.00ng mL(-1). The limits of detection and quantification were in the range of 0.02-0.06ng mL(-1) and 0.07-0.19ng mL(-1), respectively. The present method was applied to the analysis of milk samples, and the recoveries of analytes were in the range of 93.6-104.6% with the relative standard deviations ranging from 1.6% to 6.2% (n=5). The results showed that the present method was a rapid and feasible method for the determination of hormones in milk samples. PMID:23870407

  18. Salt-assisted dispersive liquid-liquid microextraction coupled with programmed temperature vaporization gas chromatography-mass spectrometry for the determination of haloacetonitriles in drinking water.

    PubMed

    Ma, Huilian; Li, Yun; Zhang, Haijun; Shah, Syed Mazhar; Chen, Jiping

    2014-09-01

    We report here a new analytical method for the simultaneous determination of seven haloacetonitriles (HANs) in drinking water by coupling salt-assisted dispersive liquid-liquid microextraction (SADLLME) with programmed temperature vaporizer-gas chromatography-mass spectrometry (PTV-GC-MS). The newly developed method involves the dispersion of the extractant in aqueous sample by addition of a few grams of salt and no dispersion liquid was required as compared to the traditional DLLME methods. The extractant (CH2Cl2, 50?L) and the salt (Na2SO4, 2.4g) were successively added to water (8mL) in a conical centrifuge tube that was shaken for 1min and centrifuged (3500rpm, 3min). The aliquot of sedimented phase (4?L) was then directly injected into the PTV-GC-MS system. The limits of detection and quantification for the HANs were 0.4-13.2ngL(-1) and 1.2-43.9ngL(-1), respectively. The calibration curves showed good linearity (r(2)?0.9904) over 3 orders of magnitude. The repeatability of the method was investigated by evaluating the intra- and inter-day precisions. The relative standard deviations (RSDs) obtained were lower than 10.2% and 7.8% at low and high concentration levels. The relative recoveries ranged from 79.3% to 105.1%. The developed methodology was applied for the analysis of seven HANs in several drinking water samples in coastal and inland cities of China. It was demonstrated to be a simple, sensible, reproducible and environment friendly method for the determination of trace HANs in drinking water samples. PMID:24997512

  19. ?-cyclodextrin functionalized meso-/macroporous magnetic titanium dioxide adsorbent as extraction material combined with gas chromatography-mass spectrometry for the detection of chlorobenzenes in soil samples.

    PubMed

    Zhang, Jiabin; Gan, Ning; Chen, Si; Pan, Muyun; Wu, Dazhen; Cao, Yuting

    2015-07-01

    A high-performance and selective adsorbent was developed for simultaneous extraction of 6 chlorobenzenes residues in soil samples by using magnetic solid phase extraction (MSPE) combined with automated SPE followed by gas chromatography-mass spectrometry (GC-MS). The adsorbent was synthesized by grafting carboxymethyl-?-cyclodextrin (CM-?-CD) on the surface of porous core-shell magnetic Fe3O4@flower like TiO2 microspheres (Fe3O4@fTiO2-CMCD), used as a carrier. The main factors (adsorbent amount, adsorption time, elution solvent, elution volume, and elution flow rate) affecting the extraction efficiency were investigated in detail. The adsorbent exhibited high loading capacity (25.6mgg(-1) for 1,3-dichlorobenzene). This maybe due to meso-/macroporous TiO2 having high specific surface area; as a carrier of the ?-cyclodextrin film, it could obviously increase the number of recognition sites. The newly developed adsorbent also showed good selectivity towards chlorobenzenes based on host-guest interactions between ?-cyclodextrin (on adsorbent's surface) and targets, which can minimize complex matrix interference in soil samples. The proposed method was successfully applied for the analysis of environmental soil samples with recovery ranging from 87.3 to 104.3%. All target compounds showed good linearities with correlation coefficients (r) higher than 0.996. The limits of quantitation for the 6 CBs were 0.03-0.09?gkg(-1). These findings confirmed meso-/macroporous structure Fe3O4@fTiO2-CMCD as a highly effective extraction material for use in trace CB analyses in complex soil samples. PMID:25990351

  20. [Determination of tris (2-chloroethyl) phosphate in leather by gas chromatography-mass spectrometry coupled with mixed-mode sorbent solid phase extraction].

    PubMed

    Zhang, Weiya; Zhu, Yuling; Wang, Chengyun; Li, Lixia; Zhang, Junqing; Xing, Jun

    2014-10-01

    Leather is one of the important exporting products to European Union (EU), and tris(2-chloroethyl) phosphate (TCEP) is a commonly used flame retardant in leather and leather products. Recently, TCEP has been classified as a kind of substance of very high concern (SVHC) by EU for its carcinogenicity and reproductive toxicity. But to date, there is not a recognized method for the determination of TCEP in leather and leather products due to the serious matrix interferences and relatively low recovery of TCEP. In this work, a home-made mixed-mode sorbent (Silica-WCX) with carboxyl and alkyl groups was tested as the sorbent of solid phase extraction (SPE) to extract TECP from leather. The results demonstrated that, making the carboxyl groups protonized under acidic condition, Silica-WCX exhibited better extraction performance towards TCEP over some frequently used commercial sorbents tested. After the optimization of the SPE conditions based on Silica-WCX, a method of gas chromatography/mass spectrometry (GC-MS) was established for the determination of TCEP in leather samples. The linear range for TCEP ranged from 0.10 to 100.0 ?g/L and the limit of quantification (LOQ, S/N = 10) was 44.46 ng/kg. The recoveries of TCEP spiked in samples at varied levels were in the range of 91.45%-99.98% with the relative standard deviations (RSDs) of 4.33%-5.97%. The method is simple, sensitive and reliable for the analysis of TCEP in leather and leather products. PMID:25739279

  1. The measurement of vitamins D2 and D3 and seven major metabolites in a single sample of human plasma using gas chromatography/mass spectrometry.

    PubMed

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

    1988-10-01

    Selected ion monitoring of vitamin D metabolites has previously been described but there has been only one detailed description of the measurement by gas chromatography/mass spectrometry (GC/MS) of a number of metabolites in a single plasma sample. We describe here a GC/MS method, using stable isotope labelled internal standards, which allows the estimation of vitamins D2 and D3, and their 25-hydroxy, 24,25-dihydroxy and 25,26-dihydroxy metabolites in a single 2 ml sample of plasma, although more is needed for the measurement of 1,25-dihydroxyvitamin D3. Plasma was extracted on Bond Elut C18 cartridges and initial fractionation carried out on Sep-Pak SIL. Straight-phase high-performance liquid chromatography was required for separation of polyhydroxylated metabolites prior to GC/MS using an LKB 2091 mass spectrometer with conventional packed columns. n-Butylboronate esters were formed across vicinal hydroxyls, followed by formation of trimethylsilyl ethers using trimethylsilylimidazole. The [M - 90 - 15]+ ion for each compound was monitored. Deuterated internal standards were not available for all metabolites and it was necessary to use (2H6)D3 and (2H6)25OHD3 as standards for the measurement of D2 and D3, and 25OHD3 and 25OHD2, respectively, and (2H6)24,25(OH)2D3 as a standard for 24,25(OH)2D3 and 25,26(OH)2D2. Although the [M - 90 - 15]+ ion of 24,25(OH)2D and 25,26(OH)2D has the same mass: charge ratio, derivatives of these compounds are completely separated in the GC system used. The intra-assay precision for all these assays is usually less than 5%. PMID:2853987

  2. Determination of thiocyanate in saliva by headspace gas chromatography-mass spectrometry, following a single-step aqueous derivatization with triethyloxonium tetrafluoroborate.

    PubMed

    Ammazzini, Sara; Onor, Massimo; Pagliano, Enea; Mester, Zoltán; Campanella, Beatrice; Pitzalis, Emanuela; Bramanti, Emilia; D'Ulivo, Alessandro

    2015-06-26

    A novel method for the determination of salivary thiocyanate is presented. Thiocyanate was converted into ethyl thiocyanate by single-step aqueous derivatization based on triethyloxonium tetrafluoroborate and measured by gas chromatography-mass spectrometry (15min runtime). The ethyl thiocyanate derivative is volatile and can be sampled from the headspace. The derivatization chemistry proposed allows for separation of the analyte from saliva matrix whose introduction in the measurement system is avoided. Quantitation of the analyte was obtained by isotope dilution, employing a (13)C-enriched thiocyanate as internal standard. Technical details and fundamental aspects of derivatization chemistry and calibration strategy are presented. The method was validated by comparison with a standard method based on ion chromatography. The two independent methodologies produced results in agreement within 3%. Also a three level spike recovery test was carried out for validation purpose and quantitative recoveries were attained. The method is fast, simple, safe, and sensitive. Measurement of a 1mL volume 50ng/g of thiocyanate standard produced a signal-to-noise ratio of 250 for the analytical peak. This method is therefore suitable for ultra-trace determination of thiocyanate (low part-per-billion range). For the application described the full detection potential of the method was not required and the sample preparation presented has been designed for quantitation of saliva samples containing 1-400?g/g of thiocyanate with a combined standard uncertainty of 2% relative for saliva samples containing 25?g/g of thiocyanate. This method was applied for the determination of thiocyanate in human saliva samples. PMID:25980693

  3. Determination of gamma-hydroxybutyric acid in biofluids using a one-step procedure with "in-vial" derivatization and headspace-trap gas chromatography-mass spectrometry.

    PubMed

    Ingels, Ann-Sofie M E; Neels, Hugo; Lambert, Willy E; Stove, Christophe P

    2013-06-28

    A headspace-trap gas chromatography-mass spectrometry (HS-trap GC-MS) method was developed to determine GHB, a low molecular weight compound and drug of abuse, in various biological fluids. Combining this relatively novel and fully automated headspace technique with "in-vial" methylation of GHB allowed for a straightforward approach. One single method could be used for all biofluids (urine, plasma, serum, whole blood or lyzed blood), requiring only 100?l of sample. Moreover, our approach involves mere addition of all reagents and sample into one vial. Following optimization of headspace conditions and trap settings, validation was performed. Although sample preparation only consists of the addition of salt and derivatization reagents directly to a 100?l-sample in a HS-vial, adequate method sensitivity and selectivity was obtained. Calibration curves ranged from 5 to 150?g/ml GHB for urine, from 2 to 150?g/ml for plasma, and from 3.5 to 200?g/ml for whole blood. Acceptable precision and accuracy (<13% bias and imprecision) were seen for all quality controls (QC's) (LLOQ-level, low, medium, high), including for the supplementary serum- and lyzed blood-based QC's, using calibration curves prepared in plasma or whole blood, respectively. Incurred sample reanalysis demonstrated assay reproducibility, while cross-validation with another GC-MS method demonstrated that our method is a valuable alternative for GHB determination in toxicological samples, with the advantage of requiring only 100?l and minimal hands-on time, as sample preparation is easy and injection automated. PMID:23664352

  4. Nature of unresolved complex mixture in size-distributed emissions from residential wood combustion as measured by thermal desorption-gas chromatography-mass spectrometry

    NASA Astrophysics Data System (ADS)

    Hays, Michael D.; Smith, N. Dean; Dong, Yuanji

    2004-08-01

    Unresolved complex mixture (UCM) is an analytical artifact of gas chromatographs of combustion source-related fine aerosol extracts. In this study the UCM is examined in size-resolved fine aerosol emissions from residential wood combustion. The aerosols are sorted by size in an electrical low-pressure impactor (ELPI) and subsequently analyzed by thermal desorption/gas chromatography/mass spectrometry (TD/GC/MS). A semiquantitative system for predicting the branched alkane, cycloalkane, alkylbenzene, C3-, C4-, C5-alkylbenzene, methylnaphthalene, C3-, C4-, C5-alkylnaphthalene, methylphenanthrene C2-, C3-alkylphenanthrene, and dibenzothiophene concentrations in the UCM is introduced. Analysis by TD/GS/MS detects UCM on each ELPI stage for all six combustion tests. The UCM baseline among the different fuel types is variable. In particular, the UCM of Pseudotsuga sp. is enriched in later-eluting compounds of lower volatility. A high level of reproducibility is achieved in determining UCM areas. UCM fractions (UCM ion area/total extracted ion chromatograph area) by individual ELPI stage return a mean relative standard deviation of 19.1% over the entire combustion test set, indicating a highly consistent UCM fraction across the ELPI size boundaries. Among the molecular ions investigated, branched alkane (m/z 57) and dibenzothiophene (m/z 212 and 226) constituents are most abundant in UCM emissions from RWC, collectively accounting for 64-95% of the targeted chemical species. The total UCM emissions span 446-756 mg/kg of dry biomass burned and correspond to an upper limit of 7.1% of the PM2.5 mass. The UCM emissions are primarily accumulation mode (0.1 ?m ? aerodynamic diameter (da) ? 1 ?m), with a geometric mean diameter (dg) range of 120.3-518.4 nm. UCM in PM2.5 is chemically asymmetric (shifted to finer da), typically clustering at da ? 1 ?m. Measurable shifts in dg and changes in distribution widths (?g) on an intratest basis suggest that the particle density may be a function of size within PM1. The potential effects these results have on regulatory affairs, human health studies, and the state of the analytical science covering organics in PM2.5 are discussed.

  5. 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.

  6. Determination of Wastewater Compounds in Sediment and Soil by Pressurized Solvent Extraction, Solid-Phase Extraction, and Capillary-Column Gas Chromatography/Mass Spectrometry

    USGS Publications Warehouse

    Burkhardt, Mark R.; Zaugg, Steven D.; Smith, Steven G.; ReVello, Rhiannon C.

    2006-01-01

    A method for the determination of 61 compounds in environmental sediment and soil samples is described. The method was developed in response to increasing concern over the effects of endocrine-disrupting chemicals in wastewater and wastewater-impacted sediment on aquatic organisms. This method also may be used to evaluate the effects of combined sanitary and storm-sewer overflow on the water and sediment quality of urban streams. Method development focused on the determination of compounds that were 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, polycyclic aromatic hydrocarbons, and high-use domestic pesticides. Sediment and soil samples are extracted using a pressurized solvent extraction system. The compounds of interest are extracted from interfering matrix components by high-pressure water/isopropyl alcohol extraction. The compounds were isolated using disposable solid-phase extraction (SPE) cartridges containing chemically modified polystyrene-divinylbenzene resin. The cartridges were dried with nitrogen gas, and then sorbed compounds were eluted with methylene chloride (80 percent)-diethyl ether (20 percent) through Florisil/sodium sulfate SPE cartridge, and then determined by capillary-column gas chromatography/mass spectrometry. Recoveries in reagent-sand samples fortified at 4 to 72 micrograms averaged 76 percent ?13 percent relative standard deviation for all method compounds. Initial method reporting levels for single-component compounds ranged from 50 to 500 micrograms per kilogram. The concentrations of 20 out of 61 compounds initially will be reported as estimated with the 'E' remark code for one of three reasons: (1) unacceptably low-biased recovery (less than 60 percent) or highly variable method performance (greater than 25 percent relative standard deviation), (2) reference standards prepared from technical mixtures, or (3) potential blank contamination. Samples were preserved by freezing to -20 degrees Celsius. The U.S. Geological Survey National Water Quality Laboratory has established a 1-year sample-holding time limit (prior to sample extraction) from the date of sample collection (if the sample is kept at -20?C) until a statistically accepted method can be used to determine the effectiveness of the sample-freezing procedure.

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

    PubMed

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

    2011-04-01

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

  8. Determination of airborne trialkyl and triaryl organophosphates originating from hydraulic fluids by gas chromatography-mass spectrometry. Development of methodology for combined aerosol and vapor sampling.

    PubMed

    Solbu, K; Thorud, S; Hersson, M; Ovrebø, S; Ellingsen, D G; Lundanes, E; Molander, P

    2007-08-17

    Methodology for personal occupational exposure assessment of airborne trialkyl and triaryl organophosphates originating from hydraulic fluids by active combined aerosol and vapor sampling at 1.5L/min is presented. Determination of the organophosphates was performed by gas chromatography-mass spectrometry. Combinations of adsorbents (Anasorb 747, Anasorb CSC, Chromosorb 106, XAD-2 and silica gel) with an upstream cassette with glass fiber or PTFE filters and different desorption/extraction solvents (CS(2), CS(2)-dimethylformamide (50:1, v/v), toluene, dichloromethane, methyl-t-butyl ether and methanol) have been evaluated for optimized combined vapor and aerosol air sampling of the organophosphates tri-isobutyl, tri-n-butyl, triphenyl, tri-o-cresyl, tri-m-cresyl and tri-p-cresyl phosphates. The combination of Chromosorb 106 and 37 mm filter cassette with glass fiber filter and dichloromethane as desorption/extraction solvent was the best combination for mixed phase air sampling of the organophosphates originating from hydraulic fluids. The triaryl phosphates were recovered solely from the filter, while the trialkyl phosphates were recovered from both the filter and the adsorbent. The total sampling efficiency on the combined sampler was in the range 92-101% for the studied organophosphates based on spiking experiments followed by pulling air through the sampler. Recoveries after 28 days storage were 98-102% and 99-101% when stored at 5 and -20 degrees C, respectively. The methodology was further evaluated in an exposure chamber with generated oil aerosol atmospheres with both synthetic and mineral base oils with added organophosphates in various concentrations, yielding total sampling efficiencies in close comparison to the spiking experiments. The applicability of the method was demonstrated by exposure measurements in a mechanical workshop where system suitability tests are performed on different aircraft components in a test bench, displaying tricresyl phosphate air concentrations of 0.024 and 0.28 mg/m(3), as well as during aircraft maintenance displaying tri-n-butyl phosphate air concentrations of 0.061 and 0.072 mg/m(3). PMID:17574560

  9. Absolute quantification of peptides by isotope dilution liquid chromatography-inductively coupled plasma mass spectrometry and gas chromatography/mass spectrometry.

    PubMed

    Liu, Rui; Hou, Xiandeng; Lv, Yi; McCooeye, Margaret; Yang, Lu; Mester, Zoltán

    2013-04-16

    Absolute quantitation of peptides/proteins in dilute calibration solutions used in various diagnostic settings is a major challenge. Here we report the absolute quantitation of peptides by non-species-specific isotope dilution liquid chromatography-inductively coupled plasma mass spectrometry (ID LC-ICPMS) based on stoichiometric Eu tagging. The method was validated by species-specific isotope dilution gas chromatography/mass spectrometry (GC/MS) analysis of constituent amino acids of the target peptide. Quantitative labeling of bradykinin peptide was accomplished with a commercially available 2',2?-(10-(2-((2,5-dioxopyrrolidin-1-yl)oxy)-2-oxoethyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl) triacetic acid (DOTA-NHS-ester) and subsequently tagged with Eu. A (151)Eu-enriched spike was used for the non-species-specific ID LC-ICPMS determination of bradykinin. The non-species-specific ID LC-ICPMS method was cross-validated by a species-specific ID GC/MS approach, which is based on the determination of phenylalanine in bradykinin to derive the concentration of the peptide in the sample. The hydrolysis of the peptide into amino acids was achieved by microwave digestion with 4 M methanesulfonic acid, and derivatization of phenylalanine with methyl chloroformate (MCF) was performed prior to its detection by GC/MS based on a (13)C-enriched phenylalanine spike. The accuracy of the method was confirmed at various concentration levels with a typical precision of better than 5% relative standard deviation (RSD) at 20 pmol for non-species-specific ID LC-ICPMS and 500 pmol for species-specific ID GC/MS. A detection limit (3 SD) of 7.2 fmol estimated for ID LC-ICPMS with a 10 ?L injection volume from three procedure blanks was obtained for bradykinin, confirming the suitability of the method for the direct determination of peptides at trace levels. To the best of our knowledge, the proposed method is the first ICPMS peptide quantification strategy which employs an independent validation strategy using species-specific ID GC/MS for amino acid quantitation. PMID:23489086

  10. Comparison of extraction methods for quantitation of methionine and selenomethionine in yeast by species specific isotope dilution gas chromatography-mass spectrometry.

    PubMed

    Yang, Lu; Sturgeon, Ralph E; McSheehy, Shona; Mester, Zoltán

    2004-11-01

    Fourteen extraction methods commonly cited in the literature were evaluated for the quantitation of methionine (Met) and selenomethionine (SeMet) in a yeast candidate certified reference material (CRM). Species specific isotope dilution (ID) gas chromatography-mass spectrometry (GC-MS) was utilized to effectively compensate for potential errors, such as losses during derivatization and clean up steps. Despite different extraction methods, the same derivatization procedure using methyl chloroformate was applied with a single exception, which was based on digestion with cyanogen bromide with 2% SnCl2 in 0.1 M HCl. Significant differences in measured Met and SeMet concentrations were obtained when different extraction methods were used. A 4 M methanesulfonic acid reflux digestion was found to be the most efficient for both analytes. Digestion with CNBr with 2% SnCl2 in 0.1 M HCl for the determination of SeMet showed the second highest extraction efficiency. Despite frequent use of enzymatic hydrolysis for the extraction of SeMet from yeast, very low extraction efficiencies for both analytes were obtained for four of eight tested methods. Among these, the highest extraction efficiencies for both analytes were obtained using 20mg pronase and 10mg lipase with incubation at 37 degrees C for 24 h. However, recoveries remained nearly 30 and 50% lower for Met and SeMet, respectively, compared to extraction with methanesulfonic acid. Lowest extraction efficiencies for both analytes were obtained when HCl or tetramethylammonium hydroxide (TMAH) digestions were used. Efficient extraction was also achieved using 200 mg (or 400 mg) of protease XIV with incubation at 37 degrees C for 72 h (or 24 h). Concentrations of 3331+/-45 and 3334+/-39 microg g(-1) (mean and one standard deviation, n = 4) for SeMet were obtained using 200 mg (72 h incubation) and 400 mg (24 h incubation) of protease XIV, respectively, in agreement with a value of 3404+/-38 microg g(-1) obtained using a methanesulfonic acid reflux. PMID:15560494

  11. Combined quantification of faecal sterols, stanols, stanones and bile acids in soils and terrestrial sediments by gas chromatography-mass spectrometry.

    PubMed

    Birk, Jago Jonathan; Dippold, Michaela; Wiesenberg, Guido L B; Glaser, Bruno

    2012-06-15

    Faeces incorporation can alter the concentration patterns of stanols, stanones, ?(5)-sterols and bile acids in soils and terrestrial sediments. A joint quantification of these substances would give robust and specific information about the faecal input. Therefore, a method was developed for their purification and determination via gas chromatography-mass spectrometry (GC-MS) based on a total lipid extract (TLE) of soils and terrestrial sediments. Stanols, stanones, ?(5)-steroles and bile acids were extracted by a single Soxhlet extraction yielding a TLE. The TLE was saponified with KOH in methanol. Sequential liquid-liquid extraction was applied to recover the biomarkers from the saponified extract and to separate the bile acids from the neutral stanoles, stanones and ?(5)-steroles. The neutral fraction was directly purified using solid phase extraction (SPE) columns packed with 5% deactivated silica gel. The bile acids were methylated in dry HCl in methanol and purified on SPE columns packed with activated silica gel. A mixture of hexamethyldisilazane (HMDS), trimethylchlorosilane (TMCS) and pyridine was used to silylate the hydroxyl groups of the stanols and ?(5)-sterols avoiding a silylation of the keto groups of the stanones in their enol-form. Silylation of the bile acids was carried out with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) containing N-trimethylsilylimidazole (TSIM). TLEs from a set of soils with different physico-chemical properties were used for method evaluation and for comparison of amounts of faecal biomarkers analysed with saponification and without saponification of the TLE. Therefore, a Regosol, a Podzol and a Ferralsol were sampled. To proof the applicability of the method for faecal biomarker analyses in archaeological soils and sediments, additional samples were taken from pre-Columbian Anthrosols in Amazonia and an Anthrosol from a site in central Europe settled since the Neolithic. The comparison of the amounts of steroids in combination with and without saponification of the TLE showed that high amounts of faecal biomarkers occur bound to other lipids and were liberated by saponification. The method was evaluated by standard addition. The standard contained 5?-stanols, 5?-stanones and their 5?-isomers together with ?(5)-sterols and bile acids (19 substances). The standard addition revealed mean recoveries of individual substances ?85%. The recoveries of biomarkers within each biomarker group did not differ significantly. Precisions were ?0.22 (RSD) and quantification limits were between 1.3 and 10 ng g(-1) soil. These data showed that the method can be applied for quantification of trace amounts of faecal steroids and for the analyses of steroid patterns to detect enhanced faeces deposition in soils and sediments. PMID:22560452

  12. Determination of polydimethylsiloxane-seawater distribution coefficients for polychlorinated biphenyls and chlorinated pesticides by solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Zeng, Eddy Y; Tsukada, David; Noblet, James A; Peng, Jian

    2005-02-25

    Applications of solid-phase microextraction (SPME) in the measurement of very hydrophobic organic compounds (VHOCs) are limited, partly due to the difficulty of calibrating SPME fibers for VHOCs. This study used a static SPME strategy with a large sample volume (1.6 L) and a five-point calibration procedure to determine the distribution coefficients for a large suite of polychlorinated biphenyls (PCBs) and chlorinated pesticides between a polydimethylsiloxane (PDMS) phase (100 microm thickness) coated on a glass fiber and seawater. An extraction time of 12 days was deemed adequate for equilibrium calibration from kinetic experiments. Two groups of randomly selected fibers divided into three batches (up to nine fibers in each batch) were processed separately with two gas chromatography-mass spectrometry (GC-MS) systems. Matrix effects arising from losses of the analytes to glass container walls and stirring bars were corrected. Relative standard deviations within the same batch were generally smaller than those for the entire group. Furthermore, KfVf (Kf and Vf are the distribution coefficient of an analyte between the polymer-coated fiber and aqueous phase and the fiber volume, respectively) values determined with two GC-MS systems were statistically different. These results indicate the calibrated KfVf values were less affected by the random selection of SPME fibers than by other experimental conditions, and therefore average KfVf values may be used for the same type of commercially available SPME fibers. The relative accuracy of our calibration method was similar to that of a previous study [P. Mayer. W.H.J. Vaes, J.L.M. Hermens, Anal. Chem. 72 (2000) 459] employing different coating thickness and calibration procedure. The present study also obtained a bell-shaped relationship between log Kf and log Kow (octanol-water partition coefficient) for PCB congeners with the maximum log Kf corresponding to log Kow approximately 6.5. This bell-shaped relationship was attributed mainly to steric effects arising from the interplay between the PDMS thickness and molecular sizes of the target analytes. PMID:15794568

  13. Microwave-assisted extraction and dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry for isolation and determination of polycyclic aromatic hydrocarbons in smoked fish.

    PubMed

    Ghasemzadeh-Mohammadi, Vahid; Mohammadi, Abdorreza; Hashemi, Maryam; Khaksar, Ramin; Haratian, Parivash

    2012-05-11

    A simple and efficient method was developed using microwave-assisted extraction (MAE) and dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry (GC-MS) for the extraction and quantification of 16 polycyclic aromatic hydrocarbons (PAHs) in smoked fish. Benzo[a]pyrene, chrysene and pyrene were employed as model compounds and spiked to smoked fish to assess the extraction procedure. Several parameters, including the nature and volume of hydrolysis, extracting and disperser solvents, microwave time and pH, were optimized. In the optimum condition for MAE, 1g of fish sample was extracted in 12 mL KOH (2M) and ethanol with a 50:50 ratio in a closed-vessel system. For DLLME, 500 ?L of acetone (disperser solvent) containing 100 ?L of ethylene tetrachloride (extraction solvent) was rapidly injected by syringe into 12 mL of the sample extract solution (previously adjusted to pH 6.5), thereby forming a cloudy solution. Phase separation was performed by centrifugation and a volume of 1.5 ?L of the sedimented phase was analyzed by GC-MS in select ion monitoring (SIM) mode. Satisfactory results were achieved when this method was applied to analyze the PAHs in smoked fish samples. The MAE-DLLME method coupled with GC-MS provided excellent enrichment factors (in the range of 244-373 for 16 PAHs) and good repeatability (with a relative standard deviation between 2.8 and 9%) for spiked smoked fish. The calibration graphs were linear in the range of 1-200 ng g(-1), with the square of the correlation coefficient (R(2))>0.981 and detection limits between 0.11 and 0.43 ng g(-1). The recoveries of those compounds in smoked fish were from 82.1% to 105.5%. A comparison of this method with previous methods demonstrated that the proposed method is an accurate, rapid and reliable sample-pretreatment method that gives very good enrichment factors and detection limits for extracting and determining PAHs from smoked fish. PMID:22483095

  14. Simultaneous determination of total fatty acid esters of chloropropanols in edible oils by gas chromatography-mass spectrometry with solid-supported liquid-liquid extraction.

    PubMed

    Liu, Qing; Han, Feng; Xie, Ke; Miao, Hong; Wu, Yongning

    2013-11-01

    This study aimed to establish a novel robust method for the simultaneous determination of total fatty acid esters of 4 chloropropanols including fatty acid esters of 3-monochloropropane-1,2-diol (3-MCPD esters), 2-monochloropropane-1,3-diol (2-MCPD esters), 1,3-dichloropropan-2-ol (1,3-DCP esters) and 2,3-dichloropropan-1-ol (2,3-DCP esters) in edible oils. In this method, sodium methylate in methanol was used as the reagent for the ester cleavage reaction of chloropropanols esters. The reaction products were extracted by a sodium sulfate solution, and then purified by solid-supported liquid-liquid extraction (SLE) using diatomaceous earth (Hydromatrix™) as the sorbent. Finally, the extracts were derivatized with heptafluorobutyrylim idazole (HFBI) and analyzed by gas chromatography-mass spectrometry (GC-MS). Quantification was achieved using deuterated chloropropanols as their respective internal standards, including 3-MCPD-d5, 2-MCPD-d5, 1,3-DCP-d5 and 2,3-DCP-d5. A good linear relationship between peak area and concentrations was obtained within the range of 0.025-2.000mgL(-1) with a correlation coefficients not less than 0.999 for all the chloropropanols esters. The limits of detection (LODs) of esters of 3-MCPD, 2-MCPD, 1,3-DCP and 2,3-DCP (calculated as corresponding chloropropanols) were 30, 30, 100 and 30?gkg(-1), respectively. The average recoveries of the 3-MCPD esters and the 4 chloropropanols spiked at 0.1, 0.5 and 2mgkg(-1) into blank oil matrix were typically in a range from 70.7% to 113.3%. The robust method validation data including calibration, LOD/LOQ, accuracy and repeatability and proficiency test results (Z-score: -0.5) of the official Food Analysis Performance Assessment Scheme (FAPAS) indicated that the present quantitative method could be successfully applied to the determination of total chloropropanols esters in various edible oils. PMID:24070627

  15. On-line monitoring of benzene air concentrations while driving in traffic by means of isotopic dilution gas chromatography/mass spectrometry.

    PubMed

    Davoli, E; Cappellini, L; Moggi, M; Ferrari, S; Fanelli, R

    1996-01-01

    There is no shortage of information about the average benzene concentrations in urban air, but there is very little about microenvironmental exposure, such as in-vehicle concentrations while driving in various traffic conditions, while refuelling, or while in a parking garage. The main reason for this lack of data is that no analytical instrumentation has been available to measure on-line trace amounts of benzene in such situations. We have recently proposed a highly accurate, high-speed cryofocusing gas chromatography/mass spectrometry (GC/MS) system for monitoring benzene concentrations in air. Accuracy of the analytical data is achieved by enrichment of the air sample before trapping, with a stable isotope permeation tube system. The same principles have been applied to a new instrument, specifically designed for operation on an electric vehicle (Ducato Elettra, Fiat). The zero emission vehicle and the fully transportable, battery-operated GC/MS system provide a unique possibility of monitoring benzene exposure in real everyday situations such as while driving, refuelling, or repairing a car. All power consumptions have been reduced so as to achieve a battery-operated GC/MS system. Liquid nitrogen cryofocusing has been replaced by a packed, inductively heated, graphitized charcoal microtrap. The instrument has been mounted on shock absorbers and installed in the van. The whole system has been tested in both fixed and mobile conditions. The maximum monitoring period without external power supply is 6 h. The full analytical cycle is 4 min, allowing close to real-time monitoring, and the minimum detectable level is 1 microgram/m3 for benzene. In-vehicle monitoring showed that, when recirculation was off and ventilation on, i.e., air from outside the vehicle was blown inside, concentrations varied widely in different driving conditions: moving from a parking lot into normal traffic on an urban traffic condition roadway yielded an increase in benzene concentration from 17 to 62.3 micrograms/m3 even if the actual distance was small. A larger increase was observed when a car was left with the engine running at a distance 2 m from the zero emission vehicle: We measured an increment of benzene concentrations from 15.2 to 174.4 micrograms/m3 with a car equipped with a catalytic converter, and from 19.1 to 386.3 micrograms/m3 with a car without such a converter. PMID:8738357

  16. High-throughput characterization of sediment organic matter by pyrolysis-gas chromatography/mass spectrometry and multivariate curve resolution: A promising analytical tool in (paleo)limnology.

    PubMed

    Tolu, Julie; Gerber, Lorenz; Boily, Jean-François; Bindler, Richard

    2015-06-23

    Molecular-level chemical information about organic matter (OM) in sediments helps to establish the sources of OM and the prevalent degradation/diagenetic processes, both essential for understanding the cycling of carbon (C) and of the elements associated with OM (toxic trace metals and nutrients) in lake ecosystems. Ideally, analytical methods for characterizing OM should allow high sample throughput, consume small amounts of sample and yield relevant chemical information, which are essential for multidisciplinary, high-temporal resolution and/or large spatial scale investigations. We have developed a high-throughput analytical method based on pyrolysis-gas chromatography/mass spectrometry and automated data processing to characterize sedimentary OM in sediments. Our method consumes 200?g of freeze-dried and ground sediment sample. Pyrolysis was performed at 450°C, which was found to avoid degradation of specific biomarkers (e.g., lignin compounds, fresh carbohydrates/cellulose) compared to 650°C, which is in the range of temperatures commonly applied for environmental samples. The optimization was conducted using the top ten sediment samples of an annually resolved sediment record (containing 16-18% and 1.3-1.9% of total carbon and nitrogen, respectively). Several hundred pyrolytic compound peaks were detected of which over 200 were identified, which represent different classes of organic compounds (i.e., n-alkanes, n-alkenes, 2-ketones, carboxylic acids, carbohydrates, proteins, other N compounds, (methoxy)phenols, (poly)aromatics, chlorophyll and steroids/hopanoids). Technical reproducibility measured as relative standard deviation of the identified peaks in triplicate analyses was 5.5±4.3%, with 90% of the RSD values within 10% and 98% within 15%. Finally, a multivariate calibration model was calculated between the pyrolytic degradation compounds and the sediment depth (i.e., sediment age), which is a function of degradation processes and changes in OM source type. This allowed validation of the Py-GC/MS dataset against fundamental processes involved in OM cycling in aquatic ecosystems. PMID:26092342

  17. Determination of a wide range of volatile organic compounds in ambient air using multisorbent adsorption/thermal desorption and gas chromatography/mass spectrometry

    USGS Publications Warehouse

    Pankow, J.F.; Luo, W.; Isabelle, L.M.; Bender, D.A.; Baker, R.J.

    1998-01-01

    Adsorption/thermal desorption with multisorbent air-sampling cartridges was developed for the determination of 87 method analytes including halogenated alkanes, halogenated alkenes, ethers, alcohols, nitriles, esters, ketones, aromatics, a disulfide, and a furan. The volatilities of the compounds ranged from that of dichlorofluoromethane (CFC12) to that of 1,2,3- trichlorobenzene. The eight most volatile compounds were determined using a 1.5-L air sample and a sample cartridge containing 50 mg of Carbotrap B and 280 mg of Carboxen 1000; the remaining 79 compounds were determined using a 5-L air sample and a cartridge containing 180 mg of Carbotrap B and 70 mg of Carboxen 1000. Analysis and detection were by gas chromatography/mass spectrometry. The minimum detectable level (MDL) concentration values ranged from 0.01 parts per billion by volume (ppbv) for chlorobenzene to 0.4 ppbv for bromomethane; most of the MDL values were in the range 0.02-0.06 ppbv. No breakthrough was detected with the prescribed sample volumes. Analyte stability on the cartridges was very good. Excellent recoveries were obtained with independent check standards. Travel spike recoveries ranged from 90 to 110% for 72 of the 87 compounds. The recoveries were less than 70% for bromomethane and chloroethene and for a few compounds such as methyl acetate that are subject to losses by hydrolysis; the lowest travel spike recovery was obtained for bromomethane (62%). Blank values for all compounds were either below detection or very low. Ambient atmospheric sampling was conducted in New Jersey from April to December, 1997. Three sites characterized by low, moderate, and high densities of urbanization/traffic were sampled. The median detected concentrations of the compounds were either similar at all three sites (as with the chlorofluorocarbon compounds) or increased with the density of urbanization/traffic (as with dichloromethane, MTBE, benzene, and toluene). For toluene, the median detected concentrations were 0.23, 0.42, and 0.70 ppbv at the three sites. Analytical precision was measured using duplicate sampling. As expected, the precision deteriorated with decreasing concentration. At concentrations greater than 0.2 ppbv, most duplicates differed by less than 20%; below the MDL values, the differences between the duplicates were larger, but they were still typically less than 40%.

  18. Determination of cis and trans -Octadecenoic acids in margarines by gas liquid chromatography-infrared spectrophotometry

    Microsoft Academic Search

    W. M. N. Ratnayake; R. Hollywood; E. O'Grady; J. L. Beare-Rogers

    1990-01-01

    A combined capillary gas liquid chromatography (GLC) and infrared spectrophotometry (IR) method is described for the determination\\u000a ofcis andtrans-octadecenoic acids in margarines made from partially hydrogenated vegetable oils. The totaltrans-unsaturation of margarine fatty acid methyl esters determined by IR, with methyl elaidate as the external standard, was correlated\\u000a to the capillary GLC weight percentages of the componenttrans fatty acid methyl

  19. Determination of nitrate in environmental water samples by conversion into nitrophenols and solid phase extraction?spectrophotometry, liquid chromatography or gas chromatography–mass spectrometry

    Microsoft Academic Search

    Nidhi Lohumi; Shefali Gosain; Archana Jain; Vinay K Gupta; Krishna K Verma

    2004-01-01

    Conversion of nitrate into a nitro-phenol derivative by reaction with 2-methylphenol or 2,6-dimethylphenol allowed at least 100-fold enrichment of the derivative on Lichrolut EN polymeric cartridge, and it is stable for up to 1 month on the cartridge. The derivative could be eluted with ammonia–methanol mixture. This reaction for nitrate determination has permitted a choice of final measurement by UV-Vis

  20. Biological monitoring of occupational exposure to toluene diisocyanate: measurement of toluenediamine in hydrolysed urine and plasma by gas chromatography-mass spectrometry.

    PubMed Central

    Persson, P; Dalene, M; Skarping, G; Adamsson, M; Hagmar, L

    1993-01-01

    Exposure to toluene diisocyanate (TDI) was studied during 48 hours and biological samples from nine subjects were taken in a factory producing flexible polyurethane (PUR) foam. Five PUR workers, two white collar workers, and two volunteers were studied. The concentrations of TDI in air were determined by high performance liquid chromatography with the 9-(N-methylaminomethyl)-anthracene reagent. Urine and plasma samples were collected and the TDI related amines, 2,4-toluenediamine (2,4-TDA) and 2,6-toluenediamine (2,6-TDA), were determined (after hydrolysis) as pentafluoropropionic anhydride (PFPA) derivatives by capillary gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring (SIM) in the negative chemical ionisation mode. The concentration of TDI in air was 1%-10% of the Swedish threshold limit value (TLV) of 40 micrograms/m3. The ratio between 2,4-TDI and 2,6-TDI varied in the air samples in the range of 60%:40%-5%:95%. Calibration plots for human urine spiked with 2,6-TDA and 2,4-TDA in the range of 0.2-12 micrograms/l were produced on eight different occasions during five weeks. The SDS of the calibration plot slopes (n = 8) were less than 4%. Urine and blood samples were taken on six occasions for eight of the studied subjects and on four occasions for one subject during a two day period. The five male PUR workers showed the highest average urinary elimination rate of TDA. Two PUR workers and the two white collar workers had an elimination rate of 20-70 ng on average for the sum of 2,6-TDA and 2,4-TDA per hour and three PUR workers had an average of 100-300 ng TDA per hour. The elimination rate curves for all the studied subjects had a linear relation with exposure to TDI. The concentrations of 2,4-TDA and 2,6-TDA in plasma for the PUR factory employees were virtually stable. No relation between the elimination rates of TDA in urine and plasma concentrations of TDA was found. The five PUR workers showed plasma concentrations of the sum of 2,4-TDA and 2,6-TDA in the range 1-8 ng per ml. The two white collar workers, present only on occasions in the factory, had 0.2- ng TDA per ml plasma. The two volunteers showed an increasing concentration of TDA in plasma with time. At the end of the study their plasma concentrations were 0.6 ng/ml and 0.2 ng/ml plasma. Three subjects had the same concentration of the two TDA isomers in plasma, two subjects had about double, and two subjects had 12 times higher concentrations of 2,6-TDA than 2,4-TDA. The presented study indicates that it is possible to monitor exposure to TDI by monitoring plasma concentrations of TDA. PMID:8280642

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

    PubMed

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

    2010-03-26

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

  2. Novel and rapid method for determination of organophosphorus pesticide residues in edible fungus using direct gas purge microsyringe extraction coupled on-line with gas chromatography-mass spectrometry.

    PubMed

    Nan, Jingxi; Wang, Juan; Piao, Xiangfan; Yang, Cui; Wu, Xue; Quinto, Maurizio; Li, Donghao

    2015-09-01

    In this work a new analytical method for a rapid and simultaneous determination of 28 organophosphorus pesticides (OPPs) residues in edible fungus using gas purge microsyringe extraction (GP-MSE), coupled with on-line gas chromatography-mass spectrometry (GP-MSE-GC-MS) has been developed and optimized. GP-MSE, a novel gas flow liquid-phase microextraction technique, has been then fruitfully used as innovative and one-step extraction procedure, allowing a direct injection into the gas chromatograph coupled with a mass spectrometry detector (GC-MS) system without any further cleaning step. Once optimized, the GP-MSE-GC-MS analysis procedure showed reproducibility values, resolutions, linear responses, detection and quantification limits that allowed to consider this method suitable for the analysis of the 28 OPPs in real samples. Furthermore, OPP recoveries and the relative standard deviations (RSDs) ranged from 85.26% to 100.21%, and from 1.6% to 6.9%, respectively. This procedure was then used for the analysis of real samples and the obtained results were compared with those of ultrasonic extraction-solid phase extraction. Among the 28 OPPs, 14 of them were found in Lentinus edodes and Enoki mushrooms fungus samples, with a total concentrations of 112.7 and 210.7?gkg(-)(1), respectively. This work demonstrated then that GP-MSE-GC-MS provided a highly efficient, solvent-saving, accurate and sensitive quantitative analysis method for a rapid determination of OPPs in edible fungus. PMID:26003693

  3. Radiation Metabolomics. 3. Biomarker Discovery in the Urine of Gamma-Irradiated Rats Using a Simplified Metabolomics Protocol of Gas Chromatography-Mass Spectrometry Combined with Random Forests Machine Learning Algorithm

    PubMed Central

    Lanz, Christian; Patterson, Andrew D.; Slavík, Josef; Krausz, Kristopher W.; Ledermann, Monika; Gonzalez, Frank J.; Idle, Jeffrey R.

    2009-01-01

    Radiation metabolomics employing mass spectral technologies represents a plausible means of high-throughput minimally invasive radiation biodosimetry. A simplified metabolomics protocol is described that employs ubiquitous gas chromatography-mass spectrometry and open source software including random forests machine learning algorithm to uncover latent biomarkers of 3 Gy ? radiation in rats. Urine was collected from six male Wistar rats and six sham-irradiated controls for 7 days, 4 prior to irradiation and 3 after irradiation. Water and food consumption, urine volume, body weight, and sodium, potassium, calcium, chloride, phosphate and urea excretion showed major effects from exposure to ? radiation. The metabolomics protocol uncovered several urinary metabolites that were significantly up-regulated (glyoxylate, threonate, thymine, uracil, p-cresol) and down-regulated (citrate, 2-oxoglutarate, adipate, pimelate, suberate, azelaate) as a result of radiation exposure. Thymine and uracil were shown to derive largely from thymidine and 2?-deoxyuridine, which are known radiation biomarkers in the mouse. The radiation metabolomic phenotype in rats appeared to derive from oxidative stress and effects on kidney function. Gas chromatography-mass spectrometry is a promising platform on which to develop the field of radiation metabolomics further and to assist in the design of instrumentation for use in detecting biological consequences of environmental radiation release. PMID:19630524

  4. Radiation metabolomics. 3. Biomarker discovery in the urine of gamma-irradiated rats using a simplified metabolomics protocol of gas chromatography-mass spectrometry combined with random forests machine learning algorithm.

    PubMed

    Lanz, Christian; Patterson, Andrew D; Slavík, Josef; Krausz, Kristopher W; Ledermann, Monika; Gonzalez, Frank J; Idle, Jeffrey R

    2009-08-01

    Abstract Radiation metabolomics employing mass spectral technologies represents a plausible means of high-throughput minimally invasive radiation biodosimetry. A simplified metabolomics protocol is described that employs ubiquitous gas chromatography-mass spectrometry and open source software including random forests machine learning algorithm to uncover latent biomarkers of 3 Gy gamma radiation in rats. Urine was collected from six male Wistar rats and six sham-irradiated controls for 7 days, 4 prior to irradiation and 3 after irradiation. Water and food consumption, urine volume, body weight, and sodium, potassium, calcium, chloride, phosphate and urea excretion showed major effects from exposure to gamma radiation. The metabolomics protocol uncovered several urinary metabolites that were significantly up-regulated (glyoxylate, threonate, thymine, uracil, p-cresol) and down-regulated (citrate, 2-oxoglutarate, adipate, pimelate, suberate, azelaate) as a result of radiation exposure. Thymine and uracil were shown to derive largely from thymidine and 2'-deoxyuridine, which are known radiation biomarkers in the mouse. The radiation metabolomic phenotype in rats appeared to derive from oxidative stress and effects on kidney function. Gas chromatography-mass spectrometry is a promising platform on which to develop the field of radiation metabolomics further and to assist in the design of instrumentation for use in detecting biological consequences of environmental radiation release. PMID:19630524

  5. Comparison of Gas Chromatography-Mass Spectrometry and Gas Chromatography-Tandem Mass Spectrometry with Electron Ionization and Negative-Ion Chemical Ionization for Analyses of Pesticides at Trace Levels in Atmospheric Samples

    PubMed Central

    Raina, Renata; Hall, Patricia

    2008-01-01

    A comparison of detection limits of gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) with gas chromatography-tandem mass spectrometry (GC-MS/MS) in selected reaction monitoring (SRM) mode with both electron ionization (EI) and negative-ion chemical ionization (NCI) are presented for over 50 pesticides ranging from organochlorines (OCs), organophosphorus pesticides (OPs) and pre-emergent herbicides used in the Canadian prairies (triallate, trifluralin, ethalfluralin). The developed GC-EI/SIM, GC-NCI/SIM, and GC-NCI/SRM are suitable for the determination of pesticides in air sample extracts at concentrations <100 pg ?L?1 (<100 pg m?3 in air). No one method could be used to analyze the range of pre-emergent herbicides, OPs, and OCs investigated. In general GC-NCI/SIM provided the lowest method detection limits (MDLs commonly 2.5–10 pg ?L?1) along with best confirmation (<25% RSD of ion ratio), while GC-NCI/SRM is recommended for use where added selectivity or confirmation is required (such as parathion-ethyl, tokuthion, carbofenothion). GC-EI/SRM at concentration <100 pg ?L?1 was not suitable for most pesticides. GC-EI/SIM was more prone to interference issues than NCI methods, but gave good sensitivity (MDLs 1–10 pg ?L?1) for pesticides with poor NCI response (OPs: sulfotep, phorate, aspon, ethion, and OCs: alachlor, aldrin, perthane, and DDE, DDD, DDT). PMID:19609395

  6. 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

  7. Assessment of the chemical changes during storage of phenol-formaldehyde resins pyrolysis gas chromatography mass spectrometry, inverse gas chromatography and Fourier transform infra red methods.

    PubMed

    Strzemiecka, B; Voelkel, A; Zi?ba-Palus, J; Lachowicz, T

    2014-09-12

    The chemical changes occurring in the phenol-formaldehyde resins (resol and novolac type) during their storage were investigated. In this paper the FT-IR, py-GCMS and inverse gas chromatography methods were applied for assessment of the changes occurring during storage of the phenolic resins. We have found that during storage some examined resins occurred partial curing. The results from all techniques applied are consistent. Py-GCMS is useful technique for screening the storage processes but IGC seems to be most sensitive one. PMID:25092596

  8. The development of sampling and gas chromatography-mass spectrometry analytical procedures to identify and determine the minor organic components of landfill gas.

    PubMed

    Brookes, B I; Young, P J

    1983-09-01

    Modified drive-in piezometers provided quick and inexpensive probes to give access to the undiluted landfill gas below ground level. Samples collected on Tenax GC and Porapak Q adsorption tubes were thermally desorbed and injected into a gas Chromatograph through a cold trap. Aqueous condensate samples were injected directly by syringe. Chromosorb 101, Tenax GC and Triton X100/KOH packed columns, and an SE30 capillary column were used, together with full-scan and selective-ion mass spectrometry. Limits of detection, all less than 1 mg m (3), and calibration correlation coefficients were determined for the least tractable components, i.e., free acids, amines and alcohols. A detection limit of 0.1 mg m (3), based on anisole as internal standard, was estimated for all other compounds. The standard deviation for the whole procedure, with full-scan mass spectrometry, was +/-55% of the mean. A large part of this was due to an instrumental error, standard deviation = 33% of the mean, that was inherent in the manual operation of the mass-spectrum chart-recorder. These procedural errors were insignificant in comparison with the variations caused by the type of site and the age of the fill. PMID:18963441

  9. 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.

  10. Development and validation of an automated static headspace gas chromatography-mass spectrometry (SHS-GC-MS) method for monitoring the formation of ethyl methane sulfonate from ethanol and methane sulfonic acid.

    PubMed

    Jacq, Karine; Delaney, Ed; Teasdale, Andrew; Eyley, Steve; Taylor-Worth, Karen; Lipczynski, Andrew; Reif, Van D; Elder, David P; Facchine, Kevin L; Golec, Simon; Oestrich, Rolf Schulte; Sandra, Pat; David, Frank

    2008-12-15

    An automated sample preparation and analysis procedure was developed to monitor the formation of ethyl methane sulfonate from reaction mixtures containing ethanol and methane sulfonic acid. The system is based on a liquid handling robot combined with a static headspace module. The formed ethyl methane sulfonate is analysed after derivatisation with pentafluorothiophenol using static headspace-gas chromatography-mass spectrometry (SHS-GC-MS). Using the automated reaction-derivatisation-headspace GC-MS system, the formation of ethyl methane sulfonate can be monitored in different reaction mixtures under different reaction conditions, including temperature, water content and pH. Excellent linearity, repeatability and robustness were obtained, allowing the system to be used in kinetic studies. PMID:18996665

  11. Comparative investigation of disposition of 3,4-(methylenedioxy)methamphetamine (MDMA) in the rat and the mouse by a capillary gas chromatography-mass spectrometry assay based on perfluorotributylamine-enhanced ammonia positive ion chemical ionization.

    PubMed

    Lim, H K; Zeng, S; Chei, D M; Foltz, R L

    1992-09-01

    A gas chromatography-mass spectrometry assay based on perfluorotributylamine-enhanced ammonia positive ion chemical ionization has been developed for MDMA and three of its primary metabolites in biological specimens; the assay is linear from 2 to 1000 ng ml-1. Quantitatively, more of an administered dose of 10 mg kg-1 MDMA was excreted by the mouse (72%) than by the rat (35%); most in both species was excreted in urine and within 24 h. The difference in per cent excretion is entirely due to proportionally greater excretion of the parent drug by the mouse. 4-Hydroxy-3-methoxymethamphetamine (HMM) is the major urinary metabolite in both species. HMM and another primary metabolite, 4-hydroxy-3-methoxyamphetamine (HMA), were excreted mainly as glucuronide and sulphate conjugates (> 85%). PMID:1363061

  12. High-performance liquid chromatography of 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 in human plasma. Use of isotachysterols and a comparison with gas chromatography--mass spectrometry.

    PubMed

    Trafford, D J; Seamark, D A; Turnbull, H; Makin, H L

    1981-12-11

    A high-performance liquid chromatographic (HPLC) method for estimating plasma 25-hydroxyvitamin D2 (25-OHD2) and 25-hydroxyvitamin D3 (25-OHD3) is described. The method involves plasma extraction, Lipidex 5000 chromatography and HPLC on straight-phase Zorbax-SIL, collecting the 25-OHD2 + 25-OHD3 fractions. These secosteroids are isomerised to their isotachysterol derivatives and re-run in the same HPLC system, monitoring at 290 nm. 3H-Labelled 25-OHD3 is used as an internal standard. The method was evaluated in terms of reproducibility, and recovery of added secosteroids was quantitative. Values obtained using this method were in close agreement with those values obtained on the same plasma sample using gas chromatography--mass spectrometry. PMID:6976351

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

    PubMed

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

    2009-04-01

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

  14. Solid-phase extraction-gas chromatography-mass spectrometry using a fullerene sorbent for the determination of inorganic mercury(II), methylmercury(I) and ethylmercury(I) in surface waters at sub-ng/ml levels.

    PubMed

    Muñoz, J; Gallego, M; Valcárcel, M

    2004-11-01

    A novel, straightforward solid-phase extraction system for the determination of inorganic mercury and organomercury compounds in water is proposed. The analytes, in a buffer medium at pH 4.5, are sorbed as diethyldithiocarbamate complexes on a C60 fullerene column an subsequently eluted and derivatized with sodium tetra-n-propylborate in ethyl acetate. Following elution, 1 microl of extract is injected into a gas chromatograph-mass spectrometer system. The proposed gas chromatography-mass spectrometry speciation method exhibits a linear range of 4-1 ng/ml, and a detection limit of 1.5 ng/l (sample volume, 50 ml). Its repeatibility, as relative standard deviation (RSD) (from 11 standards containing 50 ng/l for each analyte), is ca. 7%. No interferences from metals ions, such as Zn2+, Fe3+, Sb3+, As3+, Pb2+, Ni2+, Cu2+, Sn2+, Co2+, Mn2+ and Cd2+ were encountered at concentrations 1000 times higher than those of the mercury compounds. The method was used for the speciation of inorganic mercury, methylmercury and ethylmercury in various types of water including sea and waste water. PMID:15560495

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

    PubMed

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

    2012-02-24

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

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

    PubMed

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

    2013-04-22

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

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

    PubMed Central

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

    2014-01-01

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

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

    Microsoft Academic Search

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

    1994-01-01

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

  19. Isomer-specific separation of 2378-substituted polychlorinated dibenzo-p-dioxins by high-resolution gas chromatography\\/mass spectrometry

    Microsoft Academic Search

    Hans Rudolf. Buser; Christoffer. Rappe

    1984-01-01

    All polychlorinated dibenzo-p-dioxin (PCDD) isomers containing four and more chlorine substituents were prepared by micropyrolysis of chlorophenates. The syntheses included the preparation of all 22 tetra-, 14 penta-, 10 hexa-, 2 hepta-, and octachlorinated species (tetra- to octa-CDD). The gas chromatographic and mass spectrometric properties of these isomers were studied. High-resolution gas chromatography (HRGC) on a 55-m Silar 10 c

  20. Optimisation of programmable temperature vaporizer-based large volume injection for determination of pesticide residues in fruits and vegetables using gas chromatography–mass spectrometry

    Microsoft Academic Search

    Darinka Štajnbaher; Lucija Zupan?i?-Kralj

    2008-01-01

    The applicability of programmable temperature vaporizer (PTV) solvent vent injection to the gas chromatographic (GC) determination of pesticide residues in fruits and vegetables was evaluated with the aim of miniaturizing the current multiresidue method. For that purpose 24 pesticides representing different chemical classes were initially chosen for optimisation of the large volume injection (LVI) parameters. Various parameters related to the

  1. DETECTION OF HIGH MOLECULAR WEIGHT ORGANIC TRACERS IN VEGETATION SMOKE SAMPLES BY HIGH-TEMPERATURE GAS CHROMATOGRAPHY-MASS SPECTROMETRY. (R823990)

    EPA Science Inventory

    High-temperature high-resolution gas chromatography (HTGC) is an established technique for the separation of complex mixtures of high molecular weight (HMW) compounds which do not elute when analyzed on conventional GC columns. The combination of this technique wit...

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

    Microsoft Academic Search

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

    2005-01-01

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

  3. NATURE OF UNRESOLVED COMPLEX MIXTURE IN SIZE-DISTRIBUTED EMISSIONS FROM RESIDENTIAL WOOD COMBUSTION AS MEASURED BY THERMAL DESORPTION-GAS CHROMATOGRAPHY-MASS SPECTROMETRY

    EPA Science Inventory

    In this study, the unresolved complex mixture (UCM) in size resolved fine aerosol emissions from residential wood combustion (RWC) is examined. The aerosols are sorted by size in an electrical low-pressure impactor (ELPI) and subsequently analyzed by thermal desorbtion/gas chroma...

  4. 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…

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

    EPA Science Inventory

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

  6. Stir bar sorptive extraction-thermal desorption-gas chromatography-mass spectrometry: an effective tool for determining persistent organic pollutants and nonylphenol in coastal waters in compliance with existing Directives.

    PubMed

    Sánchez-Avila, Juan; Quintana, Jordi; Ventura, Francesc; Tauler, Romà; Duarte, Carlos M; Lacorte, Silvia

    2010-01-01

    A multi-residual method based on stir bar sorptive extraction coupled with thermal desorption-gas chromatography-mass spectrometry (SBSE-TD-GC-MS) has been developed to measure 49 organic pollutants (organochlorine pesticides, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polybrominated diphenyl ethers and nonylphenol) in seawater. Using 100ml of water, the method exhibited good linearity, with recoveries between 86% and 118% and relative standard deviation between 2% and 24% for almost all compounds. The method was applied to determine target contaminants in Catalonian seawater, including coastal areas, ports and desalination plant feed water. Overall individual compound levels oscillated between 0.16 and 597 ng l(-1); PAHs and nonylpenol were the compounds found at the highest concentrations. The method provided LODs between 0.011 and 2.5 ng l(-1), lower than the Environmental Quality Standards (EQS) fixed by Directive 2008/105/EC. In compliance with the directive, this method can be used as a tool to survey target compounds and is aimed at protecting coastal ecosystems from chemical pollution. PMID:19786286

  7. Combined microwave-assisted extraction and continuous solid-phase extraction prior to gas chromatography-mass spectrometry determination of pharmaceuticals, personal care products and hormones in soils, sediments and sludge.

    PubMed

    Azzouz, Abdelmonaim; Ballesteros, Evaristo

    2012-03-01

    This paper reports a sensitive analytical method based on microwave-assisted extraction and continuous solid-phase extraction (SPE), followed by gas chromatography-mass spectrometry (GC-MS), for the simultaneous determination of residues of 18 pharmaceuticals (analgesics, antibacterials, anti-epileptics, ?-blockers, lipid regulators and non-steroidal anti-inflammatories), one personal care product and 3 hormones in soils, sediments and sludge. The analytes are extracted with 3:2 methanol/water under the action of microwave energy and the resulting extract is passed through a SPE column to clean up the sample matrix and preconcentrate the analytes. Then, the analytes, trapped on Oasis-HLB sorbent, are eluted with ethyl acetate, silylated and determined by GC-MS. The proposed method provides a linear response over the concentration range 2.5-20,000 ng/kg with correlation coefficients higher than 0.994 in all cases. Also, it features low limits of detection (0.8-5.1 ng/kg), good precision (within- and between-day relative standard deviation less than 7%) and recoveries ranging from 91 to 101%. The method was successfully applied to agricultural soils, river and pond sediments, and sewage sludge. All samples contained some target analyte and sludge contained most -some at considerably high concentrations. PMID:22285085

  8. Quantitation of deuterated and non-deuterated phenylalanine and tyrosine in human plasma using the selective ion monitoring method with combined gas chromatography-mass spectrometry. Application to the in vivo measurement of phenylalanine-4-monooxygenase activity.

    PubMed

    Zagalak, M J; Curtius, H C; Leimbacher, W; Redweik, U

    1977-11-11

    A specific method is described for the quantitative analysis of deuterated and non-deuterated phenylalanine and tyrosine in human plasma by gas chromatography-mass spectrometry using selective ion monitoring. From the several derivatives investigated, the N- or N,O-trifluoroacetyl methyl esters were found to be the most suitable for our purposes. DL-Phenylalanine-4-d1 and L-tyrosine-d7 were used as internal standards. The sensitivity of this method permits the measurement of amounts as small as ca. 2.5 ng/ml in plasma for both phenylalanine and tyrosine. The coefficients of variation were found to be ca. 1.6% (n = 12) for phenylalanine and 3.0% (n = 12) for tyrosine. Using this method, an in vivo determination of phenylalanine-4-monooxygenase activity in humans is possible by loading the subjects with deuterated L-phenylalanine-d5 (accepted as substrate by phenylalanine-4-monooxygenase E.C. 1.14.16.1) and the subsequent measuring of deuterated L-tyrosine-d4 formed and residual L-phenylalanine-d5. PMID:914934

  9. Determination of glufosinate ammonium and its metabolite, 3-methylphosphinicopropionic acid, in human serum by gas chromatography-mass spectrometry following mixed-mode solid-phase extraction and t-BDMS derivatization.

    PubMed

    Hori, Y; Fujisawa, M; Shimada, K; Hirose, Y

    2001-01-01

    A method for the analysis of glufosinate ammonium (GLUF) and its metabolite 3-methylphosphinicopropionic acid (MPPA) in human serum by gas chromatography-mass spectrometry (GC-MS) was developed. Employing a mixed-mode cartridge with both anion exchange action and weak nonpolar interaction, we extracted GLUF and MPPA from the serum and carried out GC-MS analysis of their tert-butyldimethylsilyl derivatives. The detection limits of GLUF and MPPA were 10 pg and 1 pg, respectively. Full mass spectra of 100 pg GLUF and of 10 pg MPPA were easily obtainable. The recovery rate of 90.0+/-11.9% (or better) when the serum concentrations of GLUF and MPPA were 10-0.1 microg/mL. Results of 23 serum samples, from patients with GLUF poisoning, measured by this method correlate well with those derived from the conventional high-performance liquid chromatography method (r = 0.996). The developed GC-MS method is likely to become a useful analytical technique in clinical settings. PMID:11765024

  10. Determination of pesticide residues in olives and olive oil by matrix solid-phase dispersion followed by gas chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry.

    PubMed

    Ferrer, Carmen; Gómez, M Jose; García-Reyes, Juan F; Ferrer, Imma; Thurman, E Michael; Fernández-Alba, Amadeo R

    2005-04-01

    A novel analytical approach has been developed and evaluated for the quantitative analysis of a selected group of widely used pesticides (dimethoate, simazine, atrazine, diuron, terbuthylazine, methyl-parathion, methyl-pirimiphos, endosulfan I, endosulfan II, endosulfan sulphate, cypermethrin and deltamethrin), which can be found at trace levels in olive oil and olives. The proposed methodology is based on matrix solid-phase dispersion (MSPD), (with a preliminary liquid-liquid extraction in olive oil samples) using aminopropyl as sorbent material with a clean-up performed in the elution step with Florisil, followed by mass spectrometric identification and quantitation of the selected pesticides using both gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode and liquid chromatography tandem mass spectrometry (LC-MS-MS) in positive ionization mode. The recoveries obtained (with mean values between 85 and 115% (obtained at different fortification levels) with RSD values below 10% in most cases, confirm the usefulness of the proposed methodology for the analyses of these kind of complex samples with a high fat content. Moreover, the obtained detection limits, which were below 5 microg kg(-1) by LC-MS analyses and ranged from 10 to 60 microg kg(-1) by GC-MS meet the requirements established by the olive oil pesticide regulatory programs. The method was satisfactorily applied to different olives and olive oil samples. PMID:15830944

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

    PubMed

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

    2013-02-15

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

  12. A novel approach for the simultaneous determination of iodide, iodate and organo-iodide for 127I and 129I in environmental samples using gas chromatography-mass spectrometry.

    PubMed

    Zhang, S; Schwehr, K A; Ho, Y-F; Xu, C; Roberts, K A; Kaplan, D I; Brinkmeyer, R; Yeager, C M; Santschi, P H

    2010-12-01

    In aquatic environments, iodine mainly exists as iodide, iodate, and organic iodine. The high mobility of iodine in aquatic systems has led to (129)I contamination problems at sites where nuclear fuel has been reprocessed, such as the F-area of Savannah River Site. In order to assess the distribution of (129)I and stable (127)I in environmental systems, a sensitive and rapid method was developed which enables determination of isotopic ratios of speciated iodine. Iodide concentrations were quantified using gas chromatography-mass spectrometry (GC-MS) after derivatization to 4-iodo-N,N-dimethylaniline. Iodate concentrations were quantified by measuring the difference of iodide concentrations in the solution before and after reduction by Na(2)S(2)O(5). Total iodine, including inorganic and organic iodine, was determined after conversion to iodate by combustion at 900 °C. Organo-iodine was calculated as the difference between the total iodine and total inorganic iodine (iodide and iodate). The detection limits of iodide-127 and iodate-127 were 0.34 nM and 1.11 nM, respectively, whereas the detection limits for both iodide-129 and iodate-129 was 0.08 nM (i.e., 2pCi (129)I/L). This method was successfully applied to water samples from the contaminated Savannah River Site, South Carolina, and more pristine Galveston Bay, Texas. PMID:21069952

  13. Generation of sub-ppb level vapor phase mixtures of biogenic volatile organic compounds from liquid phase standards and stepwise characterization of their volatilization properties by thermal desorption-gas chromatography-mass spectrometry.

    PubMed

    Iqbal, Mohammad Asif; Kim, Ki-Hyun

    2014-12-19

    In the analysis of biogenic volatile organic compounds (BVOCs) in ambient air, preparation of a sub-ppb level standard is an important factor. This task is very challenging as most BVOCs (e.g., monoterpenes) are highly volatile and reactive in nature. As a means to produce sub-ppb gaseous standards for BVOCs, we investigated the dynamic headspace (HS) extraction technique through which their vapors are generated from a liquid standard (mixture of 10 BVOCs: (1) ?-pinene, (2) ?-pinene, (3) 3-carene, (4) myrcene, (5) ?-phellandrene, (6) ?-terpinene, (7) R-limonene, (8) ?-terpinene, (9) p-cymene, and (10) Camphene) spiked into a chamber-style impinger. The quantification of BVOCs was made by collection on multiple-bed sorbent tubes (STs) and subsequent analysis by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). Using this approach, sub-ppb level mixtures of gaseous BVOCs were generated at different sweep cycles. The mean concentrations of 10 BVOCs generated from the most stable conditions (i.e., in the third sweep cycle) varied in the range of 0.37±0.05 to 7.27±0.86ppb depending on the initial concentration of liquid standard spiked into the system. The reproducibility of the gaseous BVOCs generated as mixture standards, if expressed in terms of relative standard error using the concentration datasets acquired under stable conditions, ranged from 1.64 (?-phellandrene) to 9.67% (R-limonene). PMID:25464998

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

    PubMed

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

    2013-12-15

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

  15. Influence of harvest maturity and fruit logistics on pineapple (Ananas comosus [L.] Merr.) volatiles assessed by headspace solid phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC/MS).

    PubMed

    Steingass, Christof B; Grauwet, Tara; Carle, Reinhold

    2014-05-01

    Profiling of volatiles from pineapple fruits was performed at four ripening stages using headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC/MS). In total, 142 volatiles were detected, of which 132 were identified. Multivariate data analysis was carried out to assess the effect of post-harvest storage on volatiles composition of green-ripe sea-freighted pineapple in comparison to air-freighted fruits harvested at full maturity. The latter fruits were characterised by volatiles described as potent odorants in pineapples, such as ?-octalactone, ?-lactones, 1-(E,Z)-3,5-undecatriene and 1,3,5,8-undecatetraene, as well as various methyl esters. In contrast, post-harvest storage of green-ripe sea-freighted fruits resulted in an increased formation of ethyl esters, acetates, acetoxy esters and alcohols, thus allowing the authentication of sea- and air-freighted pineapples, respectively. Particularly, compounds presumably derived from methyl-branched amino acid catabolism were identified in the fruits at later post-harvest stages. In addition, physicochemical traits were determined to characterise the fruit maturity stages. PMID:24360466

  16. Characterization of surface organic components of human hair by on-line supercritical fluid extraction-gas chromatography/mass spectrometry: a feasibility study and comparison with human identification using mitochondrial DNA sequences.

    PubMed

    Benner, Bruce A; Goodpaster, John V; DeGrasse, Jeffrey A; Tully, Lois A; Levin, Barbara C

    2003-05-01

    This paper discusses results of a supercritical fluid extraction-gas chromatography/mass spectrometry (SFE-GC/MS) study of small samples ( 100 microg to 1 mg) of human scalp hair. The method offers a number of benefits including greater sensitivity than liquid extraction methods because the entire extractable mass is transferred to the analytical system, compared with only a few percent from a conventional liquid extraction/injection. The project's goals were to determine if SFE-GC/MS analyses of the surface-extractable components of an individual's hair yield consistent chemical profiles and to investigate if the profiles are sufficiently different to distinguish them from those of other individuals. In addition, the mtDNA sequences from ten of the same individuals used in the SFE-GC/MS study from four family units were determined, and, while the families were distinguishable, the maternal relations yielded identical sequences. In tandem, SFE-GC/MS and mtDNA techniques may provide valuable complementary data from forensic hair samples. PMID:12762525

  17. Novel unbreakable solid-phase microextraction fibers on stainless steel wire and application for the determination of oxadiargyl in environmental and agricultural samples in combination with gas chromatography-mass spectrometry.

    PubMed

    Es-Haghi, Ali; Baghernejad, Masoud; Bagheri, Habib

    2014-10-01

    Sol-gel based solid-phase microextraction fibers supported by a stainless steel wire were fabricated and employed for GC-MS determination of oxadiargyl in real samples. The fibers were based on four compounds with different polarity: polar and non-polar (end-capped) poly(dimethylsiloxane) (PDMS), polyethylene glycol (PEG), and poly(ethylene-propyleneglycol)-monobutyl ether (UCON). For this purpose, the surface of the stainless steel was initially modified by (3-mercaptopropyl) trimethoxysilane. The results of the modification procedure were evaluated by cyclic voltammetry and energy dispersive X-ray (EDX) spectroscopy. After the modification, four different sol-gel based SPME fibers with different values of polarity, polar and non-polar PDMS, PEG, and UCON have been prepared and investigated. They are supposed to be employed to determinate oxadiargyl in agricultural and environmental samples prior to gas chromatography-mass spectrometry analysis. Most important parameters that affect the extraction efficiency were also optimized. Under optimized conditions, the proposed method was found to be linear for the concentrations ranging from 100 ng L(-1) to 2 mg L(-1) with R(2)=0.997. Limit of detection (LOD) of 40 ng L(-1) and relative standard deviation of less than 10% were obtained. Relative recovery in environmental and agricultural samples was in the range of 73-96%. PMID:25059153

  18. A retention time locked gas chromatography-mass spectrometry method based on stir-bar sorptive extraction and thermal desorption for automated determination of synthetic musk fragrances in natural and wastewaters.

    PubMed

    Arbulu, Maria; Sampedro, M Carmen; Unceta, Nora; Gómez-Caballero, Alberto; Goicolea, M Aránzazu; Barrio, Ramón J

    2011-05-20

    A stir-bar sorptive extraction (SBSE) method followed by automated thermal desorption (ATD) coupled to gas chromatography-mass spectrometry was optimized for determining trace levels of 18 synthetic fragrances (musks). Using the method developed a retention time locked library is created and converted to a screening database. This homebuilt database can be combined with deconvolution software for the identification of musks. A factorial design was provide to evaluate the main parameters and interactions between the factors affecting the process of SBSE. Operating with de MS-detector in the full-scan mode, high sensitivity with detection limits in the low ng L(-1) range, and good linearity and repeatability were achieved for all musks. The applicability of the method developed was tested in natural waters (surface and groundwater) and wastewater of a plant treatment (WWPT). The results obtained confirmed the usefulness of the proposed method for the determination and unequivocal identification of musks. This approach enables the developed method to be used for routine screening of environmental samples and posterior rapid quantitation of the positive samples. PMID:21444087

  19. 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

  20. Detection of furan levels in select Chinese foods by solid phase microextraction-gas chromatography/mass spectrometry method and dietary exposure estimation of furan in the Chinese population.

    PubMed

    Sijia, Wu; Enting, Wang; Yuan, Yuan

    2014-02-01

    In this study, a solid phase microextraction-gas chromatography/mass spectrometry (SPMEGC/MS) method was developed to detection the levels of furan in 191 selected food products obtained from the Chinese markets. The performance of the analysis method was evaluated by some quality parameters such as limit of detection (LOD), limit of quantification (LOQ), linearity, recovery, and runto-run (n=6) and day-to-day (n=18) precisions. The LOD and the LOQ of the method were 0.059 ng/g and 0.175 ng/g, respectively. The recovery of the method in fruit juice, canned jam, and infant formula ranged from 93.25% to 104.69%. The results from this study showed that furan was detected in almost all analyzed samples. Furan contents in different food samples varied greatly according to the raw materials and processing conditions. The higher contents of furan were detected in traditional Chinese liquor (61.63 ng/g), coffee (71.36 ng/g), tea (68.28 ng/g) and pickle (85.63 ng/g). The dietary intake of furan was estimated to be 0.093 ?g/kg b.w.t/day in adults and 0.333 ?g/kg b.w.t/day in infants at 6 months. Further studies are needed to reveal other sources of dietary furan exposure. PMID:24262489

  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. Ad-hoc blocked design for the robustness study in the determination of dichlobenil and 2,6-dichlorobenzamide in onions by programmed temperature vaporization-gas chromatography-mass spectrometry.

    PubMed

    Herrero, Ana; Reguera, Celia; Ortiz, M Cruz; Sarabia, Luis A; Sánchez, M Sagrario

    2014-11-28

    An 'ad-hoc' experimental design to handle the robustness study for the simultaneous determination of dichlobenil and its main metabolite (2,6-dichlorobenzamide) in onions by programmed temperature vaporization-gas chromatography-mass spectrometry (PTV-GC-MS) is performed. Eighteen experimental factors were considered; 7 related with the extraction and clean up step, 8 with the PTV injection step and 3 factors related with the derivatization step. Therefore, a high number of experiments must be carried out that cannot be conducted in one experimental session and, as a consequence, the experiments of the robustness study must be performed in several sessions or blocks. The procedure to obtain an experimental design suitable for this task works by simultaneously minimizing the joint confidence region for the coefficient estimates and the correlation among them and with the block. In this way, the effect of the factors is not aliased with the block avoiding possible misinterpretations of the effects of the experimental factors on the analytical responses. The developed experimental design is coupled to the PARAFAC2 method, which allows solving some specific problems in chromatography when working with complex matrix such as co-elution of interferents (including silylation artifacts from the derivatization step) and small shifts in the retention time and, besides, the unequivocal identification of the target compounds according to document SANCO/12571/2013. PMID:25454144

  3. A novel headspace solid-phase microextraction method using in situ derivatization and a diethoxydiphenylsilane fibre for the gas chromatography-mass spectrometry determination of urinary hydroxy polycyclic aromatic hydrocarbons.

    PubMed

    Mattarozzi, M; Musci, M; Careri, M; Mangia, A; Fustinoni, S; Campo, L; Bianchi, F

    2009-07-24

    An innovative and simple headspace solid-phase microextraction method using a novel diethoxydiphenylsilane fibre based on in situ derivatization with acetic anhydride was optimized and validated for the gas chromatography-mass spectrometry determination of some monohydroxy metabolites of polycyclic aromatic hydrocarbons, namely 1-hydroxynaphthalene, 2-hydroxynaphtalene, 9-hydroxyfluorene, 2-hydroxyfluorene and 1-hydroxypyrene at trace levels in human urine. Enzymatic hydrolysis was applied before derivatization, whereas extraction conditions, i.e. the effects of time and temperature of extraction and salt addition were investigated by experimental design. Regression models and desirability functions were applied to find the experimental conditions providing the highest global extraction response. These conditions were found in correspondence of an extraction temperature of 90 degrees C, an extraction time of 90 min and 25% NaCl added to urine samples. The capabilities of the developed method were proved obtaining limit of quantitations in the 0.1-2 microg/l range, thus allowing the bio-monitoring of these compounds in human urine. A good precision was observed both in terms of intra-batch and inter-batch repeatability with RSD always lower than 14%. Recoveries ranging from 98(+/-3) to 121(+/-1)% and extraction yields higher than 72% were also obtained. Finally, the analysis of urine specimens of coke-oven workers revealed analytes' concentrations in the 2.2-164 microg/l range, proving the exposure to PAHs of the involved workers. PMID:19523642

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

    PubMed

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

    2014-07-23

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

  5. Purification of clenbuterol-like beta2-agonist drugs of new generation from bovine urine and hair by alpha1-acid glycoprotein affinity chromatography and determination by gas chromatography-mass spectrometry.

    PubMed

    Gallo, Pasquale; Brambilla, Gianfranco; Neri, Bruno; Fiori, Maurizio; Testa, Cecilia; Serpe, Luigi

    2007-03-21

    The control of illegal use of clenbuterol and other beta(2)-agonist drugs as growth promoters in the European Union countries has led to outlaw practices for synthesizing new concept molecules, showing similar biological activity but not detectable by test methods usually employed to perform the official monitoring programmes. The synthesis schemes of some beta(2)-agonist compounds, formally derived from clenbuterol, were found out by Italian detective authorities. These compounds were synthesised ex novo in our laboratories: then, both their molecular structures and biological activities were characterised. In this paper, we describe different strategies for purifying some beta(2)-agonist drugs of new concept, more hydrophobic than clenbuterol. A two-step clean up procedure, prior to gas chromatography-mass spectrometry analysis, was developed for the multi-residue determination of these beta(2)-agonists from bovine hair and urine. The purification strategy we chose was based on adsorption solid phase extraction and, subsequently, on specific molecular recognition by affinity chromatography. The affinity columns were homemade by coupling bovine alpha(1)-acid glycoprotein, a plasmatic acceptor for basic drugs, to a chromatographic support; their effectiveness for purifying new beta(2)-agonists was discussed. The data about method recoveries and repeatability were also reported. PMID:17386755

  6. PYROLYSIS/GAS CHROMATOGRAPHY/MASS SPECTROMETRY OF A SERIES OF BURIED WOODS AND COALIFIED LOGS THAT INCREASE IN RANK FROM PEAT TO SUBBITUMINOUS COAL.

    USGS Publications Warehouse

    Hatcher, Patrick G.; Lerch, Harry E.; Kotra, Rama K.; Verheyen, Vincent T.

    1987-01-01

    To better understand the coalification process, we have conducted numerous studies of the chemical structural composition of xylem tissue from gymosperm wood and related woods that has been coalified to varying degrees. The studies presented here, examine the chemical nature of buried and coalified xylem tissue at the molecular level. To achieve this, we employed pyrolysis/gas chromatography (py/gc) and pyrolysis/gas chromotography/mass spectrometry (py/gc/ms). Pyrolysis techniques have been used to examine peat, coal, coalified wood, and related substances. However, the technique has not been previously applied to a systematic and histologically-related series of coalified woods. It is particularly useful to compare the results from pyrolytic studies with the data obtained from solid-state **1**3C NMR.

  7. Isomer-specific separation of 2378-substituted polychlorinated dibenzo-p-dioxins by high-resolution gas chromatography/mass spectrometry

    SciTech Connect

    Buser, H.R.; Rappe, C.

    1984-03-01

    All polychlorinated dibenzo-p-dioxin (PCDD) isomers containing four and more chlorine substituents were prepared by micropyrolysis of chlorophenates. The syntheses included the preparation of all 22 tetra-, 14 penta-, 10 hexa-, 2 hepta-, and octachlorinated species (tetra- to octa-CDD). The gas chromatographic and mass spectrometric properties of these isomers were studied. High-resolution gas chromatography (HRGC) on a 55-m Silar 10 c glass capillary column allowed the separation of many of these isomers and allowed the unambiguous assignment of the toxic and environmentally hazardous 2378-substituted isomers (2378-tetra-, 12378-penta, 123478-, 123678-, and 123789-hexa-CDD). Analyses were carried out to determine the occurrence of these isomers in environmental samples and in fly ash from municipal incinerators.

  8. Simultaneous determination of phosphate esters and phthalate esters in clean room air and indoor air by gas chromatography–mass spectrometry

    Microsoft Academic Search

    Hiroyuki Toda; Kaori Sako; Yuki Yagome; Toshihiro Nakamura

    2004-01-01

    A gas chromatograph–mass spectrometry (GC–MS) method has been developed for the simultaneous determination of phosphate and phthalate esters in clean room and indoor air. Dibutyl phthalate (DBP), diethylhexyl phthalate (DEHP), trimethyl phosphate (TMP) and seven other phosphate esters present in air were collected using a Waters Sep-Pak PS Air cartridge and extracted with acetone. A quantity of 4?l of each

  9. Complete characterisation of lanolin steryl esters by sub-ambient pressure gas chromatography–mass spectrometry in the electron impact and chemical ionisation modes

    Microsoft Academic Search

    Eric Jover; Zaharie Moldovan; Josep Maria Bayona

    2002-01-01

    Steryl esters occurring in lanolin have been characterised by sub-ambient pressure gas chromatography coupled to mass spectrometry. Electron impact and chemical ionisation modes with different reagent gases have been evaluated in order to carry out unambiguous peak identification. Steryl esters with different sterol (i.e. cholesterol, lanosterol and dihydrolanosterol) and acid moieties either according to carbon number (i.e C10–C23) or isomeric

  10. Toxicological detection of pholcodine and its metabolites in urine and hair using radio immunoassay, fluorescence polarisation immunoassay, enzyme immunoassay and gas chromatography-mass spectrometry

    Microsoft Academic Search

    Hans H. Maurer; Christian F. Fritz

    1990-01-01

    Summary Pholcodine (3-O-(2'-morpholinoethyl)-morphine) is used in many countries as an antitussive without analgesic or addictive properties. It is of forensic relevance that pholcodine interferes with opiate immunoassays. In this paper a gas chromatographic-mass spectrometric (GC-MS) procedure for the precise and sensitive detection of pholcodine and its metabolites in urine and hair, after acid hydrolysis, extraction and acetylation, is presented. Furthermore,

  11. Determination of suspected fragrance allergens extended list by two-dimensional gas chromatography-mass spectrometry in ready-to-inject samples.

    PubMed

    Rey, Aurélien; Corbi, Elise; Pérès, Christophe; David, Nathalie

    2015-07-24

    A new strategy was developed to elucidate and quantify 56 (69 analytes including isomers) suspected chemically defined fragrance allergens in perfumes that were recently targeted by the Scientific Committee on Consumer Safety (SCCS). Samples were analyzed with a two-dimensional gas chromatography-quadrupole mass spectrometry system (GC-GC-MS). Method performance was evaluated by the accuracy profile approach to determine uncertainties around the regulation limit of 10mg/kg. This strategy was finally applied to 62 commercialized perfumes, analyzed in the routine workflow. Depending on the matrix, an acceptable result was obtained for 88-100% of the target analytes, which means that results were accurately defined under or above 10mg/kg. This method saves considerable time for complete analysis and could be adopted for routine analysis due to its ruggedness and cost effectiveness. PMID:26051085

  12. Pyrolysis gas chromatography-mass spectrometry to characterize organic matter and its relationship to uranium content of Appalachian Devonian black shales

    USGS Publications Warehouse

    Leventhal, J.S.

    1981-01-01

    Gas Chromatographic analysis of volatile products formed by stepwise pyrolysis of black shales can be used to characterize the kerogen by relating it to separated, identified precursors such as land-derived vitrinite and marine-source Tasmanites. Analysis of a Tasmanites sample shows exclusively n-alkane and -alkene pyrolysis products, whereas a vitrinite sample shows a predominance of one- and two-ring substituted aromatics. For core samples from northern Tennessee and for a suite of outcrop samples from eastern Kentucky, the organic matter type and the U content (<10-120ppm) show variations that are related to precursor organic materials. The samples that show a high vitrinite component in their pyrolysis products are also those samples with high contents of U. ?? 1981.

  13. Gas chromatography-mass spectrometry determination of pharmacologically active substances in urine and blood samples by use of a continuous solid-phase extraction system and microwave-assisted derivatization.

    PubMed

    Azzouz, Abdelmonaim; Ballesteros, Evaristo

    2012-04-01

    A sensitive method based on gas chromatography-mass spectrometry was used to determine 22 pharmacologically active substances (frequently used in the treatment of human and animal's diseases) including analgesics, antibacterials, anti-epileptics, antiseptics, ?-blockers, hormones, lipid regulators and non-steroidal anti-inflammatories in blood and urine samples. Samples were subjected to continuous solid-phase extraction in a sorbent column (Oasis HLB), and then the target analytes were eluted with ethyl acetate and derivatized in a household microwave oven at 350 W for 3 min. Finally, these products were determined in a gas chromatograph-mass spectrometer equipped with a DB-5 fused silica capillary column. The analyte detection limits thus obtained ranged from 0.2 to 1.3 ng L?¹ for urine samples and 0.8-5.6 ng L?¹ for blood samples. Recoveries from both blood and urine ranged from 85 to 102%, and within-day and between-day relative standard deviations were all less than 7.5%. The proposed method offers advantages in reduction of the exposure danger to toxic solvents used in conventional sample pretreatment, simplicity of the extraction processes, rapidity, and sensitivity enhancement. The method was successfully used to quantify pharmacologically active substances in human and animal (lamb, veal and pig) blood and urine. The hormones estrone and 17?-estradiol were detected in virtually all samples, and so were other analytes such as acetylsalicylic acid, ibuprofen, ketoprofen and triclosan in human samples, and florfenicol, pyrimethamine and phenylbutazone in animal samples. PMID:22391330

  14. Comparative evaluation of liquid-liquid extraction, solid-phase extraction and solid-phase microextraction for the gas chromatography-mass spectrometry determination of multiclass priority organic contaminants in wastewater.

    PubMed

    Robles-Molina, José; Gilbert-López, Bienvenida; García-Reyes, Juan F; Molina-Díaz, Antonio

    2013-12-15

    The European Water Framework Directive (WFD) 2000/60/EC establishes guidelines to control the pollution of surface water by sorting out a list of priority substances that involves a significant risk to or via the aquatic systems. In this article, the analytical performance of three different sample preparation methodologies for the GC-MS/MS determination of multiclass organic contaminants-including priority comprounds from the WFD-in wastewater samples using gas chromatography-mass spectrometry was evaluated. The methodologies tested were: (a) liquid-liquid extraction (LLE) with n-hexane; (b) solid-phase extraction (SPE) with C18 cartridges and elution with ethyl acetate:dichloromethane (1:1 (v/v)), and (c) headspace solid-phase microextraction (HS-SPME) using two different fibers: polyacrylate and polydimethylsiloxane/carboxen/divinilbenzene. Identification and confirmation of the selected 57 compounds included in the study (comprising polycyclic aromatic hydrocarbons (PAHs), pesticides and other contaminants) were accomplished using gas chromatography tandem mass spectrometry (GC-MS/MS) with a triple quadrupole instrument operated in the multiple reaction monitoring (MRM) mode. Three MS/MS transitions were selected for unambiguous confirmation of the target chemicals. The different advantages and pitfalls of each method were discussed. In the case of both LLE and SPE procedures, the method was validated at two different concentration levels (15 and 150 ng L(-1)) obtaining recovery rates in the range 70-120% for most of the target compounds. In terms of analyte coverage, results with HS-SPME were not satisfactory, since 14 of the compounds tested were not properly recovered and the overall performance was worse than the other two methods tested. LLE, SPE and HS-SPME (using polyacrylate fiber) procedures also showed good linearity and precision. Using any of the three methodologies tested, limits of quantitation obtained for most of the detected compounds were in the low nanogram per liter range. PMID:24209357

  15. Monitoring of atmospheric gaseous and particulate polycyclic aromatic hydrocarbons in South African platinum mines utilising portable denuder sampling with analysis by thermal desorption-comprehensive gas chromatography-mass spectrometry.

    PubMed

    Geldenhuys, G; Rohwer, E R; Naudé, Y; Forbes, P B C

    2015-02-01

    Concentrations of diesel particulate matter and polycyclic aromatic hydrocarbons (PAHs) in platinum mine environments are likely to be higher than in ambient air due to the use of diesel machinery in confined environments. Airborne PAHs may be present in gaseous or particle phases each of which has different human health impacts due to their ultimate fate in the body. Here we report on the simultaneous sampling of both phases of airborne PAHs for the first time in underground platinum mines in South Africa, which was made possible by employing small, portable denuder sampling devices consisting of two polydimethylsiloxane (PDMS) multi-channel traps connected in series separated by a quartz fibre filter, which only require small, battery operated portable personal sampling pumps for air sampling. Thermal desorption coupled with comprehensive gas chromatography-mass spectrometry (TD-GC×GC-TofMS) was used to analyse denuder samples taken in three different platinum mines. The samples from a range of underground environments revealed that PAHs were predominantly found in the gas phase with naphthalene and mono-methylated naphthalene derivatives being detected at the highest concentrations ranging from 0.01 to 18 ?g m(-3). The particle bound PAHs were found in the highest concentrations at the idling load haul dump vehicle exhausts with a dominance of fluoranthene and pyrene. Particle associated PAH concentrations ranged from 0.47 to 260 ng m(-3) and included benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene and benzo[ghi]perylene. This work highlights the need to characterise both phases in order to assess occupational exposure to PAHs in this challenging sampling environment. PMID:25582484

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

    USGS Publications Warehouse

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

    2000-01-01

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

  17. Methods of analysis by the U.S. Geological Survey 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.

  18. Simultaneous determination of creatinine and creatine in human serum by double-spike isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-mass spectrometry (GC-MS).

    PubMed

    Fernández-Fernández, Mario; Rodríguez-González, Pablo; Añón Álvarez, M Elena; Rodríguez, Felix; Menéndez, Francisco V Álvarez; García Alonso, J Ignacio

    2015-04-01

    This work describes the first multiple spiking isotope dilution procedure for organic compounds using (13)C labeling. A double-spiking isotope dilution method capable of correcting and quantifying the creatine-creatinine interconversion occurring during the analytical determination of both compounds in human serum is presented. The determination of serum creatinine may be affected by the interconversion between creatine and creatinine during sample preparation or by inefficient chemical separation of those compounds by solid phase extraction (SPE). The methodology is based on the use differently labeled (13)C analogues ((13)C1-creatinine and (13)C2-creatine), the measurement of the isotopic distribution of creatine and creatinine by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and the application of multiple linear regression. Five different lyophilized serum-based controls and two certified human serum reference materials (ERM-DA252a and ERM-DA253a) were analyzed to evaluate the accuracy and precision of the proposed double-spike LC-MS/MS method. The methodology was applied to study the creatine-creatinine interconversion during LC-MS/MS and gas chromatography-mass spectrometry (GC-MS) analyses and the separation efficiency of the SPE step required in the traditional gas chromatography-isotope dilution mass spectrometry (GC-IDMS) reference methods employed for the determination of serum creatinine. The analysis of real serum samples by GC-MS showed that creatine-creatinine separation by SPE can be a nonquantitative step that may induce creatinine overestimations up to 28% in samples containing high amounts of creatine. Also, a detectable conversion of creatine into creatinine was observed during sample preparation for LC-MS/MS. The developed double-spike LC-MS/MS improves the current state of the art for the determination of creatinine in human serum by isotope dilution mass spectrometry (IDMS), because corrections are made for all the possible errors derived from the sample preparation step. PMID:25751287

  19. Gas chromatography/mass spectrometry analysis of components of pyridine temperature-programmed desorption spectra from surface of copper-supported catalysts.

    PubMed

    Pribylová, Lenka; Dvorák, Bohumír

    2009-05-01

    The method of pyridine temperature-programmed desorption (TPD) was applied for the measurement of acid properties of in situ reduced copper catalysts on silicate support. A thermal-conductivity detector (TCD) was used for the detection of TPD spectra of pyridine. The combination of flame-ionization detector and thermal conductivity detector shows that the region of TPD spectrum with the peak maxima T(MAX1)=350 degrees C is a superposition of the TCD response on spectra of desorbed pyridine, water and carbon dioxide, desorbing simultaneously from the catalyst surface. The method for the elimination of H(2)O and CO(2) on the layer of NaOH was tested and the pure TPD spectrum of pyridine was obtained. The exact determination of pyridine concentration allows to estimate the amount of weak and medium acid centers of the catalyst. The gas chromatography with the mass spectroscopy (GC-MS) analyses was used for the interpretation of high temperature region of the pyridine TPD spectra (T(MAX2)=620 degrees C). It was found that pyridine bonded on the strong acid centers is decomposed to N(2) and CO under very high temperature. The available chromatographic method for the separation of components present in pyridine TPD spectrum in the high-temperature region was suggested. The method for the quantification of strong acidity of copper-supported catalyst was found. PMID:19303075

  20. Determination of multiresidue pesticides in green tea by using a modified QuEChERS extraction and ion-trap gas chromatography/mass spectrometry.

    PubMed

    Steiniger, David; Lu, Gulping; Butler, Jessie; Phillips, Eric; Fintschenko, Yolanda

    2010-01-01

    The pesticide residues in exported and imported tea products must not exceed the maximum residue limits (MRLs) regulated by the import countries. Tea is a complex matrix that obfuscates the determination of pesticide residues. Many available methods for multiresidue pesticide analysis of tea are time-consuming and require many cleanup steps. The objective of this study was to develop a simple multiresidue method by using a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction and ion-trap GC/MS/MS, which can identify, confirm, and quantify pesticides in complex matrixes. A tea product was homogenized with water, and the pesticides were extracted with acetonitrile containing 1% acetic acid. The extract was subjected to centrifugation, initial cleanup with dispersive SPE (dSPE), solvent exchange, and final cleanup with dSPE. Diethyl-d10-parathion and triphenyl phosphate were used as the internal standard and surrogate, respectively. The final extract was injected into an ITQ 700 gas chromatograph/mass spectrometer. Quantitation of individual pesticides was based on matrix-matched calibration curves with a correlation coefficient of > 0.9930 for the 22 pesticides selected for the study. The recoveries of the 22 pesticides ranged from 78 to 115%, except those for diazinon (130%) and malathion (122%), with an average RSD of 8.7%. The LOD values of all of the pesticides, except for terbufos, were below the MRLs set by the European Union and Japan. PMID:20922949

  1. Multiresidue method for determination of 90 pesticides in fresh fruits and vegetables using solid-phase extraction and gas chromatography-mass spectrometry.

    PubMed

    Stajnbaher, Darinka; Zupancic-Kralj, Lucija

    2003-10-10

    A multiresidue method for analysis of 90 pesticides with different physico-chemical properties in fruits and vegetables was developed. The method involves a rapid and small-scale extraction procedure with acetone using vortex mixing. Solid-phase extraction (SPE) on a highly cross-linked polystyrene divinylbenzene column (LiChrolut EN) was used for clean-up and pre-concentration of the pesticides from the water-diluted acetone extracts. For most fruit and vegetable samples this partial clean-up was sufficient, but some of them with more co-extracting substances need further clean-up (cereals, spinach, carrots, etc.). Diethylaminopropyl (DEA) modified silica was used for efficient removal of interferences caused by various organic acids, sugars, etc. The pesticide residues were determined by gas chromatography with a mass selective detector (GC-MS). The majority of pesticide recoveries for various fruits and vegetables were >80% in the concentration range from 0.01 to 0.50 mg/kg, except for the most polar pesticides (methamidophos, acephate, omethoate) which cannot be determined by this method. The limit of quantitation for most of the pesticides was 0.01 mg/kg with majority of relative standard deviations (R.S.D.s) below 10%. PMID:14570330

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

    PubMed

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

    2010-07-01

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

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

    PubMed

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

    2012-12-14

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

  4. High-sensitivity detection of short-chain fatty acids in porcine ileal, cecal, portal and abdominal blood by gas chromatography-mass spectrometry.

    PubMed

    Tsukahara, Takamitsu; Matsukawa, Noriko; Tomonaga, Shozo; Inoue, Ryo; Ushida, Kazunari; Ochiai, Kuniyasu

    2014-04-01

    Short-chain fatty acids (SCFA), such as acetate, propionate and n-butyrate, are the main end-products of fermentation in the large intestine. SCFA are rapidly absorbed from the large intestinal mucosa to provide energy to the host. In this study, high-sensitivity detection of SCFA was demonstrated in blood using the gas chromatometry with mass spectrometry (GC-MS). Few studies have measured SCFA in porcine blood. Therefore, SCFA concentrations in the ileal (IV), cecal (CV), portal (PV) and abdominal (AV) vein blood, urine (Ur) and saliva (Sa) were measured by GC-MS. All body fluids were collected from four 5-month-old pigs. Cecal (CD) and ileal (ID) digesta, and cecal (CM) and ileal (IM) mucosa were also collected and their corresponding SCFA concentrations were measured using ion-exclusion high-performance liquid chromatography. GC-MS analyses were successful to determine the SCFA concentrations in the porcine body fluids. n-Butyrate concentration was surprisingly high in CV and its proportion remained higher in CV than that in CD and CM. Acetate showed a constantly high proportion in all porcine body fluids. Propionate was detected at a relatively high proportion in CV, IV and PV, but was low in AV. PMID:24612389

  5. Chiral separation of new cathinone- and amphetamine-related designer drugs by gas chromatography-mass spectrometry using trifluoroacetyl-l-prolyl chloride as chiral derivatization reagent.

    PubMed

    Mohr, Stefan; Weiß, Jennifer A; Spreitz, Josef; Schmid, Martin G

    2012-12-21

    Since cathinone derivatives gained high popularity on the recreational drugs market within the past 5 years the development of analytical methods for the achiral and chiral determination of this substance class is of great interest. Not at least because it is obvious that the pharmacological potency differs between both enantiomers. Cathinones are structurally closely related to amphetamines, which have similar stimulating effects and are somehow better investigated. The goal of this research was to perform indirect enantioseparation of novel psychoactive cathinone and amphetamine derivatives. Trifluoroacetyl-l-prolyl chloride was served as chiral derivatization agent (CDA). Chromatographic separation was performed using a commercially available HP5-MS capillary column with a length of 30 m. Helium was used as carrier gas with a constant flow of 1.0 ml/min. Under optimum conditions 14 amphetamine derivatives were successfully resolved into their enantiomers and detected with the single quadrupol detector. Racemic methcathinone derivatives analyzed with the same method showed different peak areas for each of the produced diastereomeric isomers, even if they are structurally closely related to the amphetamines. Derivatization experiments with the single isomers of methcathinone led to both diastereomers whereas the S(-) enantiomer seemed to racemize more likely. Based on comparative experiments with R-(-)-?-methoxy-?-(trifluoromethyl)phenylacetyl chloride (MTPA) as CDA, racemization due to the keto-enol-tautomerism of the cathinone derivatives seemed to be responsible for this phenomenon. Nevertheless, 18 cathinone derivatives were successfully enantioseparated and an approach of quantitative evaluation is demonstrated. PMID:23058937

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

    PubMed

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

    2000-08-11

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

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

    PubMed

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

    2009-06-15

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

  8. Monitoring exposure to acrylamide by the determination of S-(2-carboxyethyl)cysteine in hydrolyzed hemoglobin by gas chromatography-mass spectrometry

    SciTech Connect

    Bailey, E.; Farmer, P.B.; Bird, I.; Lamb, J.H.; Peal, J.A.

    1986-09-01

    Acrylamide is a potent cumulative neurotoxin in animals and man. In vivo exposure to this electrophile results in the formation of a covalently bound reaction product with cysteine residues in hemoglobin. This adduct yields on acid hydrolysis S-(2-carboxyethyl)cysteine which has been analyzed by capillary gas chromatography with mass spectrometry. Globin isolated from the blood of rats exposed to acrylamide was spiked with an internal standard (globin treated in vitro with d3-acrylamide) and was then hydrolyzed with 6 N HCl. The protein hydrolysate was fractionated on a Dowex 50W H+ ion exchange column and the amino acids in the partially purified extract were determined as N-heptafluorobutyryl methyl esters using an OV-1701 fused silica capillary column. Quantitation was made by chemical ionization (isobutane) selective ion monitoring in which the ions m/z 386 (M-OCH3)+ derived from derivatized S-(2-carboxyethyl)cysteine in the sample and the corresponding ion m/z 389 from the added deuterium-labeled internal standard were monitored. The dose-response relationship between production of hemoglobin adduct and dose of acrylamide (0.1 mg/kg-5 mg/kg) is curved, showing an increasing slope with increasing doses of acrylamide.

  9. Solid-phase microextraction followed by gas chromatography-mass spectrometry for the determination of ink photo-initiators in packed milk.

    PubMed

    Negreira, N; Rodríguez, I; Rubí, E; Cela, R

    2010-06-30

    A novel, single step method for the determination of seven ink photo-initiators in carton packed milk samples is described. Solid-phase microextraction (SPME) and gas chromatography (GC), combined with mass spectrometry (MS), were used as sample preparation and determination techniques, respectively. Parameters affecting the performance of the microextraction process were thoroughly evaluated using uni- and multivariate optimization strategies, based on the use of experimental factorial designs. The coating of the SPME fibre, together with the sampling mode and the temperature were the factors playing a major influence on the efficiency of the extraction. Under final conditions, 1.5 mL of milk and 8.5 mL of ultrapure water were poured in a glass vessel, which was closed and immersed in a water boiling bath. A poly(dimethylsiloxane)-divinylbenzene (PDMS-DVB) coated fibre was exposed directly to the diluted sample for 40 min. After that, the fibre was desorbed in the injector of the GC-MS system for 3 min. The optimized method provided limits of quantification (LOQs) between 0.2 and 1 microg L(-1) and a good linearity in the range between 1 and 250 microg L(-1). The inter-day precision remained below 15% for all compounds in spiked whole milk. The efficiency of the extraction changed for whole, semi-skimmed and skimmed milk; however, no differences were noticed among the relative recoveries achieved for milk samples, from different brands, with the same fat content. PMID:20685470

  10. Evaluation of three headspace sorptive extraction coatings for the determination of volatile terpenes in honey using gas chromatography-mass spectrometry.

    PubMed

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

    2015-06-19

    Headspace sorptive extraction (HSSE) was used to preconcentrate seven monoterpenes (eucalyptol, linalool, menthol, geraniol, carvacrol, thymol and eugenol) for separation by gas chromatography and mass spectrometry (GC-MS). Three commercially available coatings for the stir bars, namely Polydimethylsiloxane (PDMS), polyacrilate (PA) and Ethylene glycol-silicone (EG-Silicone), were tested, and the influential parameters both in the adsorption and the thermal desorption steps were optimized. PDMS provided the best sensitivity for linalool, geraniol, menthol and eucalyptol, whereas EG-Silicone was best for extracting the phenolic monoterpenes studied. Considering the average obtained slopes from all compounds, PDMS pointed as the best option, and the analytical characteristics for the HSSE-TD-GC-MS method using this coating were obtained. Quantification of the samples was carried out by matrix-matched calibration using a synthetic honey. Detection limits ranged between 0.007 and 0.032ngg(-1), depending on the compound. Twelve honey samples of different floral origins were analyzed using the HSSE-GC-MS method, the analytes being detected at concentrations up to 64ngg(-1). PMID:25958092

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

    PubMed

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

    2007-01-01

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

  12. 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.

  13. Identification of endogenous metabolites in human sperm cells using proton nuclear magnetic resonance ((1) H-NMR) spectroscopy and gas chromatography-mass spectrometry (GC-MS).

    PubMed

    Paiva, C; Amaral, A; Rodriguez, M; Canyellas, N; Correig, X; Ballescà, J L; Ramalho-Santos, J; Oliva, R

    2015-05-01

    The objective of this study was to contribute to the first comprehensive metabolomic characterization of the human sperm cell through the application of two untargeted platforms based on proton nuclear magnetic resonance ((1) H-NMR) spectroscopy and gas chromatography coupled to mass spectrometry (GC-MS). Using these two complementary strategies, we were able to identify a total of 69 metabolites, of which 42 were identified using NMR, 27 using GC-MS and 4 by both techniques. The identity of some of these metabolites was further confirmed by two-dimensional (1) H-(1) H homonuclear correlation spectroscopy (COSY) and (1) H-(13) C heteronuclear single-quantum correlation (HSQC) spectroscopy. Most of the metabolites identified are reported here for the first time in mature human spermatozoa. The relationship between the metabolites identified and the previously reported sperm proteome was also explored. Interestingly, overrepresented pathways included not only the metabolism of carbohydrates, but also of lipids and lipoproteins. Of note, a large number of the metabolites identified belonged to the amino acids, peptides and analogues super class. The identification of this initial set of metabolites represents an important first step to further study their function in male gamete physiology and to explore potential reasons for dysfunction in future studies. We also demonstrate that the application of NMR and MS provides complementary results, thus constituting a promising strategy towards the completion of the human sperm cell metabolome. PMID:25854681

  14. Use of gas chromatography-mass spectrometry for the assessment of the contamination caused by small concentrations of nitrophenols in soils and sediments

    NASA Astrophysics Data System (ADS)

    Cacho, Juan-Ignacio; Campillo, Natalia; Viñas, Pilar; Hernandez-Cordoba, Manuel

    2015-04-01

    Nitrophenols (NPs) are widely distributed environmental contaminants that can be present in soils and sediments due to the degradation of some pesticides (parathion and fenitrothion) or by accidental spilling in ammunition plants or storage places. This communication reports a rapid and sensitive procedure for the determination of the most common NPs in soils by using gas chromatography coupled to mass spectrometry (GC-MS) as the analytical technique. Ultrasound assisted extraction (UAE) was employed for the extraction of the NPs from the soil samples to an organic solvent. Next, the resulting UAE extracts were submitted to dispersive liquid-liquid microextraction (DLLME) for achieving an effective preconcentration. DLLME is an easy-to-carry out, environmentally friendly separation technique involving minimal amounts of organic solvents. Since the volatility of NPs is low, as a previous stage to the GC-MS measurement the compounds were derivatized using a simple "in-situ" acetylation procedure. The main parameters affecting the UAE stage, as well as the DLLME and derivatization steps, were investigated looking for maximum analytical signals. The optimized procedure provided extraction recoveries in the 72-86% range, with precision values (expressed as relative standard deviation, RSD) ? 12%, and detection limits ranging from 1.3 and 3.3 ng g-1, depending on the compound. 20 soil and sediment samples, from military, industrial and agricultural areas were analyzed by the studied procedure in order to check its applicability.

  15. Storage stability studies for tributyltin determination in human urine samples using headspace solid-phase microextraction and gas chromatography mass spectrometry.

    PubMed

    Zachariadis, G A; Tzollas, N M; Nikolaou, M; Rosenberg, E

    2013-03-01

    A headspace solid-phase micro-extraction (HS-SPME) method was employed in order to study the effect of storage conditions of human urine samples spiked with tributyltin (TBT) using gas chromatography and mass spectrometry. To render the analyte more volatile, the derivatization (ethylation) was made in situ by sodium tetraethylborate (NaBEt(4) ), which was added directly to dilute unpreserved urine samples and in buffers of similar acidity. The stability of TBT in human urine matrix was compared with the stability of TBT in buffer solutions of similar pH value. Critical parameters of storage conditions such as temperature and time, which affect the stability of TBT in this kind of matrix, were examined extensively. The tests showed that the stability of TBT remains practically satisfactory for a maximum of 2 days of storage either at +4 or 20°C. Greater variations were observed in the concentration of TBT in human urine samples at +4°C and lower ones at -20°C over a month's storage. The freeze-thaw cycles have negative effect on the stability and should be kept to a minimum. The results from spiked urine samples are also discussed in comparison to those acquired from buffer solutions of equal TBT concentration. PMID:22825966

  16. Comparison of tetraethylborate and tetraphenylborate for selenite determination in human urine by gas chromatography mass spectrometry, after headspace solid phase microextraction.

    PubMed

    Kapsimali, D C; Zachariadis, G A

    2010-01-15

    Two different derivatizing reagents were tested for the development of a fast and sensitive method for the determination of selenites (Se(IV)) in human urine. The reagents were sodium tetraethylborate (NaBEt(4)) and tetraphenylborate (NaBPh(4)), respectively, and the procedure is based on in situ derivatization of selenites in aqueous medium. Selenite ions are converted to diethylselenide (DESe) or diphenylselenide (DPhSe) and subsequently collected from the headspace by solid phase microextraction using a silica fiber coated with polydimethylsiloxane (HS-SPME). Finally, they are quantitated by GC/MS in SIM mode. Ethylation over phenylation was proved preferable for the headspace extraction because of the higher volatility of the diethyl-derivative of selenites. The optimization of the HS-SPME conditions was performed both in aqueous and urinary solutions. Under the optimum conditions for HS-SPME, the gas chromatographic conditions were also optimized. Between the two alkylation reagents tetraethylborate was proved more efficient and the quantitation was satisfactory. Aqueous certified reference materials were analyzed to evaluate the accuracy of the method. The precision of the method was 4.2% and the calculated detection limit was 0.05microgL(-1) for human urine. PMID:20006093

  17. Rapid determination of alkylphenols in aqueous samples by in situ acetylation and microwave-assisted headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry.

    PubMed

    Wu, Yu-Pei; Wang, Yu-Chen; Ding, Wang-Hsien

    2012-08-01

    A rapid and solvent-free procedure for the determination of 4-tert-octylphenol and 4-nonylphenol isomers in aqueous samples is described. The method involves in-situ acetylation and microwave-assisted headspace solid-phase microextraction prior to their determination using gas chromatography-ion trap mass spectrometry operated in the selected ion storage mode. The dual experimental protocols to evaluate the effects of various derivatization and extraction parameters were investigated and the conditions optimized. Under optimized conditions, 300 ?L of acetic anhydride mixed with 1 g of potassium hydrogencarbonate and 2 g of sodium chloride in a 20 mL aqueous sample were efficiently extracted by a 65 ?m polydimethylsiloxane-divinylbenzene fiber that was located in the headspace when the system was microwave irradiated at 80 W for 5 min. The limits of quantitation were 5 and 50 ng/L for 4-tert-octylphenol and 4-nonylphenol isomers, respectively. The precision for these analytes, as indicated by relative standard deviations, were less than 8% for both intra- and inter-day analysis. Accuracy, expressed as the mean extraction recovery, was between 74 to 88%. A standard addition method was used to quantitate 4-tert-octylphenol and 4-nonylphenol isomers, and the concentrations ranged from 120 to 930 ng/L in various environmental water samples. PMID:22899640

  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. Development of a thermal desorption gas chromatography-mass spectrometry method for quantitative determination of haloanisoles and halophenols in wineries' ambient air.

    PubMed

    Camino-Sánchez, F J; Ruiz-García, J; Zafra-Gómez, A

    2013-08-30

    An analytical method for the detection and quantification of haloanisoles and their corresponding halophenols in wineries' ambient air was developed. The target analytes were haloanisoles and halophenols, reported by previous scientific literature as responsible for wine taint. A calibrated pump and active tubes filled with Tenax GR™ were used for sampling. These tubes were thermally desorbed and analyzed using gas chromatography-triple quadrupole mass spectrometry in the selected reaction monitoring mode. The adsorption efficiencies of five commercial sampling tubes filled with different materials were evaluated. The efficiencies of the selected adsorbent were close to 100% for all sampled compounds. Desorption, chromatographic and mass spectrometric conditions were accurately optimized allowing very low limits of quantification and wide linear ranges. The limits of quantification in ambient air ranged from 0.8pgtube(-1) for 2,4,6-trichlorophenol, to 28pgtube(-1) for pentachlorophenol. These results are of great importance because human sensory threshold for haloanisoles is very low. The chromatographic method was also validated and the instrumental precision and trueness were established, a maximum RSD of 9% and a mean recovery of 91-106% were obtained. The proposed method involves an easy and sensitive technique for the early detection of haloanisoles and their precursor halophenols in ambient air avoiding contamination of wine or winery facilities. PMID:23891369

  20. On-line derivatization utilizing solid-phase microextraction (SPME) for determination of busulphan in plasma using gas chromatography-mass spectrometry (GC-MS).

    PubMed

    Abdel-Rehim, Mohamed; Hassan, Zuzana; Blomberg, Lars; Hassan, Moustapha

    2003-06-01

    Busulphan (Bu) is an alkylating agent used in preparative regimen before stem cell transplantation (SCT). Bu has a narrow therapeutic window, and underdosing or overdosing may have a fatal outcome for the patient. Therapeutic drug monitoring (TDM) combined with dose adjustment is currently used to optimize and individualize therapy with Bu. However, this approach is limited to centers with laboratory facilities. An automated and easy method for measurement of Bu plasma concentrations may facilitate TDM for Bu and thus improve the clinical outcome. A solid-phase microextraction (SPME) on line with gas chromatography (GC) and mass-spectrometric detection to quantify Bu in human plasma samples was developed using in-vial derivatization. Bu was mixed with reagent in a 2-mL vial and shaken for 15 minutes at 80 degrees C; subsequently, the SPME fiber was immersed into the vial for 15 minutes. The fiber was washed in water for 10 seconds before injection. Several parameters influencing the extraction and recovery were studied, such as absorption and desorption times, the effects of the temperature on the reaction, and the shaking time on the derivatization yield. Carbowax-divinylbenzene, polyacrylate, and polydimethylsiloxane fibers were tested. The carbowax-divinylbenzene fiber resulted in the highest recovery in plasma samples. The validation of the method showed a high chromatographic selectivity and a good sensitivity (LOQ = 20 ng/mL). Coefficient of variation for SPME was less than 15%. The results showed good correlation between Bu concentrations and response within the range of 40 to 2500 ng/mL (R2 = 0.999). The accuracy ranged from 94% to 106%. This is well in line with the international criteria for validation. The present method was applied to patient plasma. The obtained results were comparable with the results obtained from GC with electron capture detection. The authors conclude that this method has shortened the analysis time considerably and is fully automated, which benefits TDM of Bu in SCT patients. PMID:12766572