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1

Gas Chromatography -Mass Spectrometry  

E-print Network

GCMS - 1 Gas Chromatography - Mass Spectrometry GC-MS ANALYSIS OF ETHANOL AND BENZENE IN GASOLINE Last updated: June 17, 2014 #12;GCMS - 2 Gas Chromatography - Mass Spectrometry GC-MS ANALYSIS). The goal of this experiment is to separate the components in a sample of gasoline using Gas Chromatography

Nizkorodov, Sergey

2

Marketability and Feasibility of Chair-Side Gas Chromatography Mass Spectrometer for Dental Application  

E-print Network

Marketability and Feasibility of Chair-Side Gas Chromatography Mass Spectrometer for Dental Chromatography Mass Spectrometer (GCMS) analysis. The ability to provide such signature profiles during a typical

Zhou, Yaoqi

3

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

ERIC Educational Resources Information Center

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

Gochman, Nathan; And Others

1979-01-01

4

Gas Chromatography-Mass Spectrometry Experiment  

NSDL National Science Digital Library

Gas Chromotography-Mass Spectrometry (GC-MS) is an analysis used in many laboratory testing situations. This laboratory exercise explains this method and uses this method to analyse DMSO. This exercise includes images and screenshots, as well as group discussion questions and questions for individual exploration of mass spectrometry online. Users may download this experiment in Microsoft Word doc file format.

Solow, Mike

5

Cell Wall Chemotyping for Functional Applications of PyrolysisGas Chromatography / Mass  

E-print Network

Cell Wall Chemotyping for Functional Genomics Applications of Pyrolysis­Gas Chromatography / Mass­Gas Chromatography / Mass Spectrometry Abstract The interest in lignocellulose as a sustainable resource for energy-Gas Chromatography/Mass Spectrom- etry (Py-GC/MS) provides a chemical fingerprint with more than hundred peaks

6

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

USGS Publications Warehouse

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.

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

1977-01-01

7

Estimation of brassylic acid by gas chromatography-mass spectrometry  

SciTech Connect

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.

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

2010-10-29

8

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

PubMed

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

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

2012-09-21

9

Study of the microbiodegradation of terpenoid resin-based varnishes from easel painting using pyrolysisgas chromatographymass spectrometry and gas chromatographymass spectrometry  

Microsoft Academic Search

The alterations produced by microbiological attack on terpenoid resin-based varnishes from panel and canvas paintings have\\u000a been evaluated using pyrolysisgas chromatographymass spectrometry (PyGCMS) and gas chromatographymass spectrometry (GCMS).\\u000a The proposed methods include the on-line derivatisation of drying oils and diterpenoid resins using hexamethyldisilazane during\\u000a pyrolysis and the application of methyl chloroformate as a derivatisation reagent for triterpenoid resins in GCMS.

Mara Teresa Domnech-Carb; Laura Osete-Cortina; Juana de la Cruz Caizares; Fernando Bolvar-Galiano; Julio Romero-Noguera; Mara Antonia Fernndez-Vivas; Ins Martn-Snchez

2006-01-01

10

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

PubMed

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

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

1977-01-01

11

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

EPA Science Inventory

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

12

Chemical Composition of Latent Fingerprints by Gas Chromatography-Mass Spectrometry  

ERIC Educational Resources Information Center

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.

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

2007-01-01

13

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 ...

14

Neonatal ketosis is not rare: experience of neonatal screening using gas chromatographymass spectrometry  

Microsoft Academic Search

The causes and effects of transient neonatal ketosis, discovered during a pilot study of screening for abnormalities in neonatal metabolism using gas chromatographymass spectrometry, were investigated. Of the 21?342 neonates that were screened, 47 had significant ketosis. The organic acid profile accompanying ketosis in the urine of neonates followed the pattern of ketotic dicarboxylic aciduria in approximately half of the

Takahiro Inokuchi; Ichiro Yoshida; Akiyo Kaneko; Kyoko Tashiro; Satomi Tashiro; Misa Jogo; Kumiko Aoki; Masatoshi Tanaka

2001-01-01

15

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

ERIC Educational Resources Information Center

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

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

2013-01-01

16

Chemical Discrimination in Turbulent Gas Mixtures with MOX Sensors Validated by Gas Chromatography-Mass Spectrometry  

PubMed Central

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

Fonollosa, Jordi; Rodrguez-Lujn, Irene; Trincavelli, Marco; Vergara, Alexander; Huerta, Ramn

2014-01-01

17

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

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

18

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

PubMed

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

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

2013-06-01

19

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

PubMed

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 m0.32 mm1.0 ?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

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

2011-01-01

20

Direct analysis of several Fusarium mycotoxins in cereals by capillary gas chromatographymass spectrometry  

Microsoft Academic Search

A method for qualitative and quantitative analysis of Fusarium mycotoxins by gas chromatographymass spectrometry (GCMS) using cold on-column injection was improved. Eight typical mycotoxins, including deoxynivalenol (DON), 3-acetyldeoxynivalenol (3ADN), fusarenon-X (FX), diacetoxyscirpenol (DAS), 15-monoacetylscirpenol (15MAS), T-2 toxin (T-2), scirpentriol (SCT), and zearalenone (ZEA) were subjected to GCMS without chemical derivatization by means of the on-column injection technique. Chromatographic separation of

Yoshiki Onji; Yoshinari Aoki; Naoto Tani; Kiyoshi Umebayashi; Yoshimi Kitada; Yoshiko Dohi

1998-01-01

21

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

SciTech Connect

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.

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

22

Identification of higenamine and its metabolites in rat by gas chromatography\\/mass spectrometry  

Microsoft Academic Search

()-Higenamine is known as a cardiotonic principle of aconite root (root ofAconitum spp., Ranunculaceae). A simple and sensitive detection method for higenamine was developed by using gas chromatography-mass\\u000a spectrometry (GC\\/MS). The recovery of higenamine after extraction and concentration with XAD-2 resin column was around 95%\\u000a from rat biological fluids such as bile, plasma and urine. The limits of detection of

Jae-Chun Ryu; Yun-Seon Song; Myungsoo Kim; Jung-Hyuck Cho; Hye Sook Yun-Choi

1993-01-01

23

Determination of imidazole and triazole fungicide residues in honeybees using gas chromatographymass spectrometry  

Microsoft Academic Search

An analytical method employing clean up by high-performance gel permeation chromatography (HPGPC) and solid-phase extraction (SPE) on Florisil cartridges was developed to determine residues of eleven imidazole and triazole ergosterol-biosynthesis-inhibiting (EBI) fungicides in honeybee samples. Detection was by means of gas chromatographymass spectrometry (GCMS) in selected ion monitoring (SIM) mode. The method was validated by fortifying control samples at levels

Andrew J. A. Charlton; Ainsley Jones

2007-01-01

24

Detection of Artificial Musk in Xihuangwan by Gas Chromatography-mass Spectrometery.  

PubMed

Objective To control the quality of Xihuangwan by improving the qualitative detection of artificial musk inside this pill. Method The qualitative detection of artificial musk was carried out by gas chromatography-mass spectrometery(GC-MS). Result The established GC-MS successfully detected artificial musk in Xihuangwan. Conclusion GC-MS is reliable,accurate,and practical in the identification of artificial must inside Xihuangwan. PMID:25556729

Liu, Wei; Zou, Qin-Wen; Cheng, Xian-Long; Zhang, Ping; Shi, Yan; Wei, Feng; Zhang, Shu; Lun, Li-Jun; Yu, De-Quan

2014-12-30

25

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

Microsoft Academic Search

We have developed a gas chromatography-mass spectrometry (GCMS) 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

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

2010-01-01

26

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

Microsoft Academic Search

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

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

1998-01-01

27

Assay of serum allantoin in humans by gas chromatographymass spectrometry  

Microsoft Academic Search

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 chromatographymass spectrometry (GCMS) assay for serum allantoin and report a reference range in healthy individuals. Methods: Fasting blood samples were obtained from 134 healthy middle-aged volunteers

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

2002-01-01

28

Gas chromatography-mass spectrometry method for determination of biogenic volatile organic compounds emitted by plants.  

PubMed

Gas chromatography-mass spectrometry (GC-MS) is one of the most widely used methods for analyzing the emissions of biogenic volatile organic compounds (VOCs) from plants. Preconcentration of VOCs on the cartridges filled with different adsorbents is a well-accepted method for sampling of headspace. Here, we describe a gas-chromatographic method for determination of different isoprenoids (isoprene, monoterpenes, homoterpenes, and sesquiterpenes). The technique is based on adsorption of compounds of interest on multibed adsorbent cartridges followed by thermodesorption, and detection and analysis by GC-MS. PMID:24777796

Knnaste, Astrid; Copolovici, Lucian; Niinemets, lo

2014-01-01

29

Qualitative Gas Chromatography-Mass Spectrometry Analyses Using Amines as Chemical Ionization Reagent Gases  

NASA Astrophysics Data System (ADS)

Ammonia is a very useful chemical ionization (CI) reagent gas for the qualitative analyses of compounds by positive ion gas chromatography-mass spectrometry (GCMS). The gas is readily available, inexpensive, and leaves no carbon contamination in the MS source. Compounds of interest to our laboratory typically yield abundant protonated or ammoniated species, which are indicative of a compound's molecular weight. Nevertheless, some labile compounds fragment extensively by substitution and elimination reactions and yield no molecular weight information. In these cases, a CI reagent gas mixture of methylamine in methane prepared dynamically was found to be very useful in obtaining molecular weight data. Likewise, deuterated ammonia and deuterated methylamine are useful CI reagent gases for determining the exchangeable protons in organic compounds. Deuterated methylamine CI reagent gas is conveniently prepared by dynamically mixing small amounts of methylamine with excess deuterated ammonia.

Little, James L.; Howard, Adam S.

2013-12-01

30

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

PubMed

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

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

2011-06-24

31

Simultaneous determination of cinnamaldehyde and its metabolite in rat tissues by gas chromatography-mass spectrometry.  

PubMed

Cinnamaldehyde (CA), an active ingredient isolated from the traditional Chinese medicine Cortex Cinnamomi, has a wide range of bioactivities. To clarify the distribution characteristics of CA, a selective and sensitive method utilizing gas chromatography-mass spetrometry was initially developed for simultaneously determining the concentration of CA and its metabolite cinnamyl alcohol in rat tissues. Selected ion masses of m/z 131, 105 and 92 were chosen, and separation of the analytes was performed on a DB-5?ms (30?m??0.25?mm, 0.25?m, thickness) capillary column by gas chromatography-mass spectrometry. The calibration curves demonstrated good linearity and reproducibility over the range of 20-2000 and 20-4000?ng/mL for various tissue samples. Recoveries ranged from 86.8 to 107.5%, while intra- and interday relative standard deviations were all <11.3%. The analysis method was successfully applied in tissue distribution studies for CA and cinnamyl alcohol. As CA and cinnamyl alcohol may inter-convert to one another, simultaneous determination of both analytes provides a comparative and accurate data for tissue study. The concentrations of CA and cinnamyl alcohol remaining in spleen were the highest among the main organs, including heart, liver, spleen, lung, kidney and brain. In addition, there was no long-term accumulation of CA in rat tissues. Copyright 2014 John Wiley & Sons, Ltd. PMID:24898181

Zhao, Hang; Yang, Qian; Xie, Yanhua; Sun, Jiyuan; Tu, Honghai; Cao, Wei; Wang, Siwang

2015-02-01

32

Comprehensive two-dimensional gas chromatography-mass spectrometry: Recent evolution and current trends.  

PubMed

The present contribution is focused on the evolution and current trends of comprehensive two-dimensional gas chromatography-mass spectrometry (GC??GC-MS), with respect to a review that described this specific methodology published at the beginning of 2008 (Mondello et al., 2008). In fact, since then there has been considerable evolution in the MS field, certainly exceeding that observed in GC??GC. In particular, the present paper will cover the combination of novel MS machines [single quadrupole (Q) and triple quadrupole, isotope ratio, low- and high-resolution time-of-flight (ToF), hybrid (Q-ToF)] to GC??GC systems, and will position comprehensive two-dimensional gas chromatography within the wider context of separation science. 2014 Wiley Periodicals, Inc. Rapid Commun. Mass Spectrom. XX: 1-11, 2014. PMID:25269651

Tranchida, Peter Q; Franchina, Flavio A; Dugo, Paola; Mondello, Luigi

2014-09-30

33

[A case of chloropicrin detection by purge and trap gas chromatography/mass spectrometry].  

PubMed

Chloropicrin (CP) is an agricultural chemical used as insecticide or fungicide, which occasionally causes accidental poisoning and may used in criminal cases including suicide and homicide. Although CP is usually analyzed using gas chromatography/electron capture detection technique (GC/ECD), further identification by gas chromatography/mass spectrometry (GC/MS) may be required from the view point of forensic chemistry and also clinical toxicology. However, it is very difficult to detect a trace of CP by routine GC/MS. The present paper describes a criminal case, in which GC/MS equipped with curie point purge and trap sampler was successfully applied to detect a small amount of CP. PMID:14582358

Ishizawa, Fujio; Ishiwata, Tetsuya; Miyata, Katsufumi; Yoshida, Tsutomu

2003-07-01

34

Verification of Chemical Composition of Commercially Available Propolis Extracts by Gas Chromatography-Mass Spectrometry Analysis.  

PubMed

Abstract 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

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

2014-09-01

35

Investigation of hexabromocyclododecane thermal degradation pathways by gas chromatography/mass spectrometry.  

PubMed

The decomposition products of hexabromocyclododecane (HBCD), a widely used brominated flame retardant, were investigated by gas chromatography/mass spectrometry (GC/MS). HBCD thermal degradation was conducted under a moderate heating rate (10 degrees C/min) in a batch reactor using both inert and oxidizing atmospheres. GC/MS analysis allowed the identification of substances derived from the primary pyrolysis process at the moderate heating rates used. The presence of oxygen seems to have a negligible influence on the degradation products obtained in HBCD decomposition, at least at moderate heating rates. Based on the identified products, the main pathways of HBCD thermal degradation were assessed and a mechanism for HBCD decomposition was proposed. The results obtained indicate that hexa-, penta- and tetrabrominated polyaromatic structures seem not to be primary products of HBCD decomposition, and may only be obtained by secondary bromination reactions. PMID:11319791

Barontini, F; Cozzani, V; Cuzzola, A; Petarca, L

2001-01-01

36

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

PubMed

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

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

2011-09-28

37

[Differentiation of ballpoint pen inks by thermodesorption and gas chromatography-mass spectrometry].  

PubMed

Differentiation and classification of ink entries with dated samples of a reference collection are important aspects in the examination of questioned documents. Classification of writing inks is presently achieved by analysis of dyes and colorants contained in the ink. This technique has its limitations in newly developed ink formulations with identical dye composition but differing in their solvents and binder resins. This paper introduces a method for the determination of solvents and binder resins of an ink sample directly from paper without sample preparation. This aim is accomplished by thermodesorption of the sample followed by gas chromatography/mass spectroscopy. The method was tested on numerous samples of ballpoint pen inks, which were subsequently grouped into several solvent and resin subgroups. A case study shows the applicability of the newly developed method. PMID:15666970

Bgler, Jrgen; Buchner, Hans; Dallmayer, Anton

2004-01-01

38

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

PubMed Central

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 AC and schizandrols A and B, were quantitatively determined using a validated GC-MS method. PMID:24574919

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

2014-01-01

39

Procedure for detecting and confirming pentobarbital residues in dog food by gas chromatography/mass spectrometry.  

PubMed

The method described detects and confirms presence of pentobarbital residues in dry, extruded feeds at concentrations of 5-20 ppb. Dried feed is ground to a uniform powder and shaken overnight in methanol. A portion of the methanolic extract is evaporated, and the residue is reconstituted in phosphate-buffered saline. The aqueous extract is cleaned with a solid-phase extraction cartridge designed to extract barbiturate residues from biological matrixes. Dimethyl sulfoxide, tetramethylammonium hydroxide, and iodomethane are added to derivatize pentobarbital, 1,3-Dimethyl-pentobarbital is then acidified with dilute hydrochloric acid and extracted with isooctane. The organic layer is transferred and evaporated under a stream of nitrogen. The residue is reconstituted in a small volume of ethyl acetate for analysis by gas chromatography/mass spectrometry. The limit of detection is approximately 0.7 ppb. The method was validated with pentobarbital-fortified feed samples containing high concentrations of meat and bone meal. PMID:9549069

Adam, L A; Reeves, V B

1998-01-01

40

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

EPA Science Inventory

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

41

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

EPA Science Inventory

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

42

Qualitative Analysis of Herbs by Gas Chromatography\\/Mass Spectrometry (GC\\/MS). An Undergraduate Instrumental Analysis Laboratory Exercise  

Microsoft Academic Search

A laboratory exercise to be used in an undergraduate instrumental methods course is presented for the qualitative analysis of interesting real-world herbal extracts. The objective of this experiment is to familiarize students with a modern experimental method gas chromatography\\/mass spectrometry (GC\\/MS).

JEREMY TIPTON; TICIA BARNICKI; EUGENE T. SMITH

1998-01-01

43

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

ERIC Educational Resources Information Center

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

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

2011-01-01

44

Chem 355 Jasperse Gas Chromatography-Mass Spectroscopy BACKGROUND Every type of chromatography depends on the distribution of a substance  

E-print Network

GC-MS 35 Chem 355 Jasperse Gas Chromatography-Mass Spectroscopy BACKGROUND Every type of chromatography depends on the distribution of a substance between two phases, a mobile phase and a stationary phase. Recall that in the liquid/solid chromatography the mobile phase was liquid flowing over

Jasperse, Craig P.

45

Identification of corrosion inhibiting long-chain primary alkyl amines by gas chromatography and gas chromatography-mass spectrometry  

NASA Astrophysics Data System (ADS)

Gas chromatography with flame-ionization detection (FID) and gas chromatography-mass spectrometry (GC/MS) has been used to identify long-chain primary alkyl amines after derivatization with trifluoroacetic anhydride (TFAA)E Electron impact ionization (EI) and positive chemical ionization (PCI) mass spectra of trifluoroacetylated derivatives of the identified alkyl amines are presented. The corrosion inhibiting alkyl amines were applied in the investigation of a new anticorrosive and antifouling formulation for water-steam circuit of energy systems in the power industry.

Kusch, Peter; Knupp, Gerd; Hergarten, Marcus; Kozupa, Marian; Majchrzak, Maria

2007-05-01

46

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

SciTech Connect

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

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

1997-07-01

47

Direct analysis of several Fusarium mycotoxins in cereals by capillary gas chromatography-mass spectrometry.  

PubMed

A method for qualitative and quantitative analysis of Fusarium mycotoxins by gas chromatography-mass spectrometry (GC-MS) using cold on-column injection was improved. Eight typical mycotoxins, including deoxynivalenol (DON), 3-acetyldeoxynivalenol (3ADN), fusarenon-X (FX), diacetoxyscirpenol (DAS), 15-monoacetylscirpenol (15MAS), T-2 toxin (T-2), scirpentriol (SCT), and zearalenone (ZEA) were subjected to GC-MS without chemical derivatization by means of the on-column injection technique. Chromatographic separation of the toxins extracted from barley was achieved as a single peak, and the specific EI mass spectra of each toxin were obtained. The fatty acids in the extract that interfere with measurements of the toxins on the gas chromatogram were removed by precipitation as an insoluble metal soap with zinc acetate. Additional clean-up was accomplished using a Bond Elut Florisil cartridge. The quantitative detection limit in barley ranged from 0.1 to 0.5 micrograms/g. The average recoveries of 93.1% for DON, 3ADN, 15MAS, DAS, T-2 and ZEA, and 46.0% for FX and SCT added to barley at the level of 1 microgram/g were obtained. PMID:9718707

Onji, Y; Aoki, Y; Tani, N; Umebayashi, K; Kitada, Y; Dohi, Y

1998-07-31

48

Gas-liquid chromatography-mass spectrometry of trimethylsilyl ethers of bile alcohols.  

PubMed

This report describes the gas-liquid chromatography-mass spectrometry (GLC-MS) of the trimethylsilyl ethers of 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha-triol with mono- or dihydroxy substitution in the side chain. Compounds with 24- and 25-unsaturation in the side chain were also studied. The gas-liquid chromatographic separation of the different bile alcohols was carried out using 3% QF-1 and 1% HI-EFF 8BP as column packings. Both columns were useful in that the retention times of the trimethyl-silyl ethers of the various 5 beta-cholestanetetrols varied linearly with the position of the side-chain trimethylsiloxyl substituent. The major fragmentations in the GLC-MS of all bile alcohols tested were due to the trimethylsiloxyl side-chain substituent(s). A trimethylsiloxyl group at C-22 was the most effective in promoting side-chain fragmentation, followed, in order of decreasing effectiveness, by substituents at carbons 25, 23, 24, and 26. The side-chain fragments generally gave rise to one or two intense mass peaks and a series of weaker peaks, 90 mass units apart, owing to the loss of successive molecules of trimethylsilanol. Most 5 beta-cholestane-triols, -tetrols, and -pentols can be unequivocally identified by their strong side-chain fragmentation peaks, except for 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 26-tetrol, the trimethylsilyl ether of which exhibited very low intensity side-chain fragments. PMID:731130

Tint, G S; Dayal, B; Batta, A K; Shefer, S; Cheng, F W; Salen, G; Mosbach, E H

1978-11-01

49

Determination of Morphine and Codeine in Human Urine by Gas Chromatography-Mass Spectrometry  

PubMed Central

A sensitive and selective gas chromatography-mass spectrometry (GC-MS) method was developed and validated for the determination of morphine and codeine in human urine. The GC-MS conditions were developed. The analysis was carried out on a HP-1MS column (30?m 0.25?mm, 0.25??m) with temperature programming, and Helium was used as the carrier gas with a flow rate of 1.0?mL/min. Selected ion monitoring (SIM) mode was used to quantify morphine and codeine. The derivation solvent, temperature, and time were optimized. A mixed solvent of propionic anhydride and pyridine (5?:?2) was finally used for the derivation at 80C for 3?min. Linear calibration curves were obtained in the concentration range of 252000.0?ng/mL, with a lower limit of quantification of 25?ng/mL. The intra- and interday precision (RSD) values were below 13%, and the accuracy was in the range 87.2108.5%. This developed method was successfully used for the determination of morphine and codeine in human urine for forensic identification study. PMID:24222889

Zhang, Xiaoqian; Cao, Gaozhong; Hu, Guoxin

2013-01-01

50

[Microstructural characterization for pyrolysis hydrogenation fragments in polyethylene by pyrolysis hydrogenation gas chromatography/mass spectrometry].  

PubMed

The microstructural characterization of 47 samples, respectively of high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), copolymer of ethylene and alpha-olefins, was performed by pyrolysis hydrogenation gas chromatography/mass spectrometry (Py-H-GC/MS) with 10% Pt on 80-100 mesh Diasolid H as a hydrogenation catalyst. The samples were obtained from 12 domestic plants and 12 plants abroad as well. The sample sizes ranging from 30 to 80 microg were pyrolyzed at 770 degrees C in a flow of hydrogen carrier gas. It was found that short methyl branches as the characteristic isoalkanes of pyrolysis hydrogenation in polyethylene would be related closely to the different classes of polyethylene. The microstructural characterization has been carried out by means of Py-H-GC/MS, according to the relative amount of the four short methyl branches, 5-methyldodecane (5-MC12), 4-methyldodecane (4-MC12), 2-methyldodecane (2-MC12) and 3-methyldodecane (3-MC12) existed in C12-C13 isoalkanes. The Py-H-GC/MS technique will be providing further scientific evidences for the characterization of polyethylene plastics in forensic science. PMID:17165536

Ding, Junkai; Song, Ming; Huang, Li

2006-09-01

51

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

SciTech Connect

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

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

2010-09-01

52

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

PubMed

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

Shahar, T; Dagan, S; Amirav, A

1998-06-01

53

Curie-point pyrolysis-gas chromatography/mass spectrometry in the art field. 2--The characterization of proteinaceous binders.  

PubMed

Curie point pyrolysis with gas chromatography/mass spectrometry has been employed to characterize some proteinaceous media used in the art field as painting binders: milk casein, egg yolk, egg albumin, bone glue, skin glue, rabbit glue and fish glue. A careful analysis of the gas chromatograms so obtained has led to the distinction of the different proteinaceous binders in terms of different chromatographic profiles. Some of the pyrolysis products have been identified by library search. PMID:8759333

Carbini, M; Stevanato, R; Rovea, M; Traldi, P; Favretto, D

1996-01-01

54

Gas chromatography-mass spectrometric method for metabolic profiling of tobacco leaves.  

PubMed

A gas chromatography-mass spectrometric method was developed for profiling of tobacco leaves. The differentiation among tobacco leaves planted in two different regions was investigated. Prior to analysis, the extraction solvent formulation was optimized and a combination of water, methanol and acetonitrile with a volume ratio of 3:1:1 was found to be optimal. The reproducibility of the method was satisfactory. Kendall tau-b rank correlation coefficients were equal to 1 (p<0.05) for 82% of the resolved peaks (up to 95% of the overall peak areas), indicating the good response correlation. Forty-four compounds including 9 saccharides, 9 alcohols, 9 amino acids, 16 organic acids and phosphoric acid were identified based on standard compounds. The method was successfully applied for profiling of tobacco leaves from Zimbabwe and Yunnan of China. Our result revealed that levels of saccharides and their derivatives including xylose, ribose, fructose, glucose, turanose, xylitol and glyceric acid were more abundant while sucrose, glucitol and D-gluconic acid were less abundant in tobacco leaves from Yunnan as compared to those from Zimbabwe. Amino acids such as L-alanine, L-tyrosine and L-threonine were found to be richer in Zimbabwe tobacco than in Yunnan tobacco. PMID:21560246

Li, Yong; Pang, Tao; Li, Yanli; Wang, Xiaolin; Li, Qinghua; Lu, Xin; Xu, Guowang

2011-06-01

55

Determination of residual clopidol in chicken muscle by capillary gas chromatography/mass spectrometry.  

PubMed

Clopidol was extracted from chicken with acetonitrile, and the extract was evaporated to about 5 mL. The concentrated solution was centrifuged and applied to a glass column filled with basic alumina. The column was eluted with methanol and the methanol was evaporated to dryness. The residue was derivatized with Sylon BFT and analyzed by gas chromatography/mass spectrometry (GC/MS). Mass characteristics of trimethylsilyl derivative of clopidol were interpreted manually. The selected-ion monitoring mode was performed at m/z 191, 248, 263, and 265. A sensitive, reproducible GC/MS method was developed for monitoring residues of clopidol in chickens. All recoveries of the drug from chicken muscle fortified at 1, 10, and 100 ng/g were > 65%, and relative standard deviations were < 15%. The detection limit was about 0.5 ng/g, and the quantitation limit was the lower limit of the standard curve, which was about 1 ng/g. PMID:16152927

He, Limin; Liu, Yahong; Zeng, Zhenling; Huang, Xianhui; Liu, Rong

2005-01-01

56

Study on essential oils from four species of Zhishi with gas chromatographymass spectrometry  

PubMed Central

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

2014-01-01

57

Determination of emulsion explosives with Span-80 as emulsifier by gas chromatography-mass spectrometry.  

PubMed

A novel approach for identification and determination of emulsion explosives with Span-80 (sorbitol mono-oleate) as the emulsifier and their postblast residues by gas chromatography-mass spectrometry (GC-MS) has been developed. 24 kinds of emulsion explosives collected have been processed by transesterification reaction with metholic KOH solution and the emulsifier has turned into methyl esters of fatty acids. From the peak area ratios of their methyl esters, most of these emulsion explosives can be differentiated. In order to detect the postblast residues of emulsion explosives, the sorbitols in the emulsifier Span-80 obtained after transesterification reaction have been further derivatized by silylation reaction with N,O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA) containing 1% trimethylchlorosilane (TMCS) as the derivatizing reagent. The derivatization conditions were optimized and the derivatives were determined by GC-MS. The results showed that the silylation derivatives of sorbitol and it isomers, combined with hydrocarbon compounds and methyl esters of fatty acids, were the characteristic components for identification of the emulsion explosives. The established approach was applied to analyze the postblast residues of emulsion explosives. It has been found that the method was sensitive and specific, especially when detecting the derivatives of sorbitol and its isomers by GC-MS in selecting ion mode. The information of the characteristic components can help probe the origin of the emulsion explosives and providing scientific evidences and clues for solving the crimes of the emulsion explosive explosion. PMID:21497820

Tian, Fei-Fei; Yu, Jing; Hu, Jia-Hong; Zhang, Yong; Xie, Meng-Xia; Liu, Yuan; Wang, Xiang-Feng; Liu, Hai-Ling; Han, Jie

2011-06-01

58

[Determination of hormone multi-residues in animal tissues by gas chromatography-mass spectrometry].  

PubMed

A method of gas chromatography-mass spectrometry (GC-MS) for the simultaneous determination of nine sex hormone residues, such as hexestrol, diethylstilbestrol, dienestrol, etiocholan-3alpha-ol-17-one, epitestosterone, estrone, estradiol, ethinylestradiol and estriol, in animal tissues was developed. The sex hormones were extracted with acetonitrile, then cleaned-up with a C18 solid-phase extraction (SPE) column. The microwave-assisted derivatization of the target components with N,O-bis( trimethylsilyl) trifluoroacetamide (BSTFA) and trimethylchlorosilane (TMCS) (99:1, v/v) using pyridine as solvent was performed, and then the derivatives were analyzed by GC-MS. The limits of detection were 0.1-1 microg/kg for all hormones, and the limits of quantification were 0.2-2 microg/kg. The average recoveries of sex hormones were 68.8%-93.1%. The relative standard deviations (RSDs) of inter- and intra-assay were 4.1%-22.3% and 3.1%-17.9%, respectively. The real sample tests showed this method can be used for the sensitive and accurate determination of multi-sex hormones residues in biological samples. PMID:19803132

Lin, Weixuan; Dong, Weifeng; Chen, Xi; Tian, Miao; Yu, Ling; Zhao, Jinghong; Yang, Chunguang

2009-05-01

59

[Determination of five representative ultraviolet filters in water by gas chromatography-mass spectrometry].  

PubMed

A method for the determination of five representative organic UV filters: ethylhexyl methoxycinnamate (EHMC), benzophenone-3 (BP-3), 4-methylbenzylidene camphor (4-MBC), octocrylene (OC), homosalate (HMS) in water was investigated. The method was ased on derivatization, solid phase extraction (SPE), followed by determination with gas chromatography-mass spectrometry (GC-MS). The variables involved in the derivatization of BP-3 and HMS were optimized, and SPE conditions were studied. For derivatization, 100 microL N,O-bis(trimethylsilyl) trifluoroacetamide (BSTFA) was used as derivatization reagent and reacted with BP-3 and HMS at 100 degrees C for 100 min. For SPE, the pH value of water sample was adjusted to 3-5. The Oasis HLB cartridges were employed and the solution of ethyl acetate and dichloromethane (1 : 1, v/v) was used as the eluting solvent, and good recoveries of the target compounds were obtained. The limits of detection (LODs) and the limits of quantification (LOQs) for the five target compounds in water samples were 0.5-1.2 ng/L and 1.4-4.0 ng/L, respectively. The recoveries of spiked water samples were 87.85%-102.34% with good repeatability and reproducibility (RSD < 5%, n = 3) for all the target compounds. Finally, the validated method was applied to analysis the representative UV filters in water samples collected from a wastewater treatment plant in Kunming city of Yunnan province. PMID:25269262

Ding, Yiran; Huang, Yun; Zhao, Tingting; Cai, Qian; Luo, Yu; Huang, Bin; Zhang, Yuxia; Pan, Xuejun

2014-06-01

60

Enhanced analysis of steroids by gas chromatography/mass spectrometry using microwave-accelerated derivatization.  

PubMed

Derivatization of steroids is typically required before analysis by gas chromatography/mass spectrometry (GC/MS); nevertheless, the derivatization process can often be time-consuming and irreproducible. Although several strategies have been employed to enhance this process, few have the potential of microwave-accelerated derivatization (MAD) to be more efficient than traditional thermal derivatization methods. MAD using a synthesis microwave system was evaluated and compared to traditional thermal derivatization methods in terms of yield, reproducibility, and overall analysis time. Parameters affecting MAD, including reaction temperature, time, and power, were systematically optimized for several silyl reagents (BSTFA with TMCS, MSTFA, and BSA) and other derivatization procedures (MOX reagent and MTBSTFA). MSTFA was found to derivatize best with the microwave, as demonstrated by the enhanced relative response factors (RRFs). BSTFA with TMCS, on the other hand, did not couple as well, but RRF values improved significantly upon addition of polar solvents. The rapid (1 min) derivatization reactions associated with MAD had comparable RRFs for all reagents with those obtained with thermal heating (>30 min). This study highlights the best methods for analyzing a comprehensive variety of steroids and also provides ideal strategies for MAD of steroids on an individual or class level. PMID:19606839

Bowden, John A; Colosi, Dominic M; Stutts, Whitney L; Mora-Montero, Diana C; Garrett, Timothy J; Yost, Richard A

2009-08-15

61

Determination of oxadiazon residues by headspace solid-phase microextraction and gas chromatography-mass spectrometry.  

PubMed

A method for the determination of trace amounts of the herbicide oxadiazon was developed using headspace solid-phase microextraction (HS-SPME), gas chromatography-mass spectrometry (GC-MS) and selected ion monitoring. It was applied to determine oxadiazon in ground water, agricultural soil, must, wine and human urine samples. To determine oxadiazon in liquid samples, a response surface methodology generated with a Doehlert design was applied to optimize the HS-SPME conditions using a 100 microm polydimethylsiloxane fibre. For the analysis of soil samples, they were mixed with water and the SPME fibre suspended in the headspace above the slurry. Ground water, human urine and must show linear concentration range of application of 0.5-50 ng ml(-1)' with detection limits < or =0.02 ng ml(-1). HS-SPME-GC-MS analysis yielded good reproducibility (RSD values between 6.5 and 13.5%). The method validation was completed with spiked matrix samples. The developed analytical procedure is solvent free, cost effective and fast. PMID:11873973

Navaln, Alberto; Prieto, Avismelsi; Araujo, Lilia; Vlchez, Jos Luis

2002-02-01

62

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

NASA Astrophysics Data System (ADS)

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.

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

2011-11-01

63

Measurement of F2- isoprostanes and isofurans using gas chromatographymass spectrometry  

PubMed Central

F2-Isoprostanes (IsoPs) are isomers of prostaglandin F2? formed from the nonenzymatic free radical-catalyzed peroxidation of arachidonic acid. Since discovery of these molecules by Morrow and Roberts in 1990, F2-IsoPs have been shown to be excellent biomarkers as well as potent mediators of oxidative stress in vivo in humans. Isofurans (IsoFs) are also oxidation products generated from the none-nzymatic oxidation of arachidonic acid. IsoFs are preferentially formed instead of F2-IsoPs in settings of increased oxygen tension. The protocol presented herein is the current methodology that our laboratory uses to quantify F2-IsoPs and IsoFs in biological tissues and fluids using gas chromatography/mass spectrometry (GC/MS). A variety of analytical procedures to measure F2-IsoPs, including other GC/MS methods and liquid chromatography/MS and immunological approaches, are reported in the literature. This method provides a very low limit of quantitation and is suitable for analysis of both F2-IsoPs and IsoFs from a variety of biological sources including urine, plasma, tissues, cerebral spinal fluid, exhaled breath condensate, and amniotic fluid, among others. PMID:23044261

Milne, Ginger L.; Gao, Benlian; Terry, Erin S.; Zackert, William E.; Sanchez, Stephanie C.

2015-01-01

64

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

PubMed Central

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

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

2012-01-01

65

Presence of phthalate esters in intravenous solution evaluated using gas chromatography-mass spectrometry method.  

PubMed

Di-(2-ethylhexyl) phthalate (DEHP) is a plasticizer widely used in the production of poly-(vinyl) chloride (PVC) materials. It is a reproductive and developmental toxicant in animals and a suspected endocrine modulator in humans. DEHP is not covalently bound within the PVC molecule, which is why migration into a suitable medium can be expected. Since application of infusion solutions is one of the most common medical treatments, the objective of this study was to determine the migration of phthalates from softened PVC storage bags into infusion solution in different time periods within one year from date of production using a gas chromatography-mass spectrometry method. The measured values of DEHP ranged between 0.22 and 14.00?g l(-1) , but the unexpected presence of other phthalate esters was also detected. It was concluded that values obtained in infusion solutions match the reference data and represent a minor risk for the patient. The presence of other phthalate esters leads to the conclusion that the pharmacopeic requirement for polymer cleanness was not fully met. Since phthalate esters are among the most extensively used industrial chemicals and are widely distributed in the environment, special precautions and further monitoring should be conducted to minimize any possible health risks. PMID:22034089

Strac, Ivona Vidi?; Pui?, Maja; Gajski, Goran; Garaj-Vrhovac, Vera

2013-03-01

66

Identification and differentiation of dragon's blood in works of art using gas chromatography/mass spectrometry.  

PubMed

Dragon's blood is a common but non-specific name for red-coloured resins that are produced by various plants, particularly exudations from plant species belonging to the genera Dracaena and Daemonorops. Although dragon's blood is mentioned in historic sources as a colourant, it has hardly ever been identified in real artworks. This paper reports the identification and discrimination of dragon's blood produced by Dracaena cinnabari, Dracaena draco as well as Daemonorops draco and Daemonorops micracantha by means of gas chromatography/mass spectrometry (GC/MS) within the context of a routine analysis of binding media used in works of art. The detection of specific flavonoid marker compounds in both underivatised and methylated methanol extracts provided the first evidence for the use of dragon's blood from all four species in various works of art from the fifteenth to nineteenth centuries. Dragon's blood was mainly used as a red colourant in gold lacquers as well as translucent glazes and paints, e.g. in reverse-glass paintings (Hinterglasmalerei). PMID:20349349

Baumer, Ursula; Dietemann, Patrick

2010-06-01

67

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

PubMed Central

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 100600, 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

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

68

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

PubMed

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

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

2007-09-14

69

Profiling of serum metabolites in canine lymphoma using gas chromatography mass spectrometry.  

PubMed

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

Tamai, Reo; Furuya, Masaru; Hatoya, Shingo; Akiyoshi, Hideo; Yamamoto, Ryohei; Komori, Yoshiaki; Yokoi, Shin-Ichi; Tani, Kenichiro; Hirano, Yuji; Komori, Masayuki; Takenaka, Shigeo

2014-12-01

70

Determination of five phthalate monoesters in human urine using gas chromatography-mass spectrometry.  

PubMed

We have developed a gas chromatography-mass spectrometry (GC-MS) method to determine five phthalate monoesters (monoethyl phthalate (MEP), mono-n-butyl phthalate (MBP), mono-(2-ethylhexyl) phthalate (MEHP), monoisononyl phthalate (MINP) and monobenzyl phthalate (MBz)) in human urine. Human urine samples were subjected to enzymatic deconjugation of the glucuronides followed by extraction with hexane. The extracted phthalate monoesters were methylated with diazomethane, purified on a Florisil column and then subjected to GC-MS analysis. The recoveries from urine spiked with five phthalate monoesters were 86.3%-119% with coefficients of variation of 0.6%-6.1%. We measured phthalate monoester levels in human urine by analyzing 36 samples from volunteers. MBP and MEP were detected in all samples, and their median concentrations were 60.0 and 10.7 ng/mL, respectively. MBzP and MEHP were found in 75% and 56% of samples, and their median concentrations were 10.9 and 5.75 ng/mL, respectively. MINPs were not detected in most samples (6% detectable). Women had significantly (p < 0.05) higher mean concentrations of MBP and MEP than men. The estimated daily exposure levels for the four parent phthalates excluding diisononyl phthalate ranged from 0.27 to 5.69 mug/kg/day (median). PMID:20574658

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

2010-07-01

71

Analysis of extractable organic compounds in water by gas chromatography mass spectrometry: applications to surface water.  

PubMed

Contamination of water by organic pollutants is a common environmental problem. Over a period of 1 year, the surface water of a canal network (Languedoc-Roussillon area, France) was analysed in order to identify organic compounds and to monitor its quality. Pollutants were extracted from 19 l of raw water using methylene chloride in a continuous countercurrent liquid-liquid extractor with a pulsed column. The extraction was performed at a pH above 11 and again at a pH below 2 according to U.S. Environmental Protection Agency method 625. The extract was analysed by gas chromatography/mass spectrometry, using two ionization techniques, namely electron ionization and chemical ionization. Mass spectra obtained by electron ionization were compared with those in a database (NIST). Some natural compounds and micropollutants were identified. Their structures were confirmed by chemical ionization (methane). One hundred and ten substances, making up the broad spectrum of extractable compounds in the surface water studied, were found by this method at a nanogram per litre concentration level. Among them, 13 are priority pollutants. These specific pollutants were qualified. PMID:18966498

Deroux, J M; Gonzalez, C; Le Cloirec, P; Kovacsik, G

1996-03-01

72

Optimization of focused ultrasonic extraction of propellant components determined by gas chromatography/mass spectrometry.  

PubMed

A method for focused ultrasonic extraction of nitroglycerin, triphenyl amine and acetyl tributyl citrate presented in double-base propellant samples following by the gas chromatography/mass spectrometry analysis was developed. A face-centered central composite design of the experiments and response surface modeling was used for optimization of the time, amplitude and sample amount. The dichloromethane was used as the extractant solvent. The optimal extraction conditions with respect to the maximum yield of the lowest abundant compound triphenyl amine were found at the 20 min extraction time, 35% amplitude of ultrasonic waves and 2.5 g of the propellant sample. The results obtained under optimal conditions were compared with the results achieved with validated Soxhlet extraction method, which is typically used for isolation and pre-concentration of compounds from the samples of explosives. The extraction yields for acetyl tributyl citrate using both extraction methods were comparable; however, the yield of ultrasonic extraction of nitroglycerin and triphenyl amine was lower than using Soxhlet extraction. The possible sources of different extraction yields are estimated and discussed. PMID:22967558

Fry, Ond?ej; ?esla, Petr; Bajerov, Petra; Adam, Martin; Ventura, Karel

2012-09-15

73

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

PubMed

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

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

2013-01-01

74

Determination of alkylbenzenesulfonates in recent sediments by gas chromatography/mass spectrometry.  

PubMed

Alkylbenzenesulfonates together with soap are the most widely used anionic surfactants. Linear alkylbenzenesulfonates (LAS) were introduced in the mid-1960s as substitutes for the poorly biodegradable tetrapropylenebenzenesulfonates (TPS). A method is presented for the selective and quantitative determination of LAS and TPS in recent sediments. Alkylbenzenesulfonates were extracted from sediments using methanol. The methanolic extract was passed through a strong anionic exchange column. The alkylbenzenesulfonates contained in the acidic eluate were then derivatized to their corresponding trifluoroethyl esters and quantitatively determined by gas chromatography/mass spectrometry using positive chemical ionization. Limits of quantitation for 10 g sediment samples varied between 1.5 and 21 ?g/kg of dry sediment for single LAS isomers and between 71 and 220 ?g/kg for total LAS. Limits of quantitation for the total of TPS were at ?200 ?g/kg. Relative standard deviations of replicate analyses typically ranged from 5 to 10%. Recovery rates of LAS in spiked sediment samples ranged from 79 to 113%. The presented method was applied to surface and subsurface sediments also containing long-chain (C(14)-C(16))-LAS and mixtures of LAS and TPS. PMID:21639162

Reiser, R; Toljander, H O; Giger, W

1997-12-01

75

Derivatization followed by gas chromatography-mass spectrometry for quantification of ethyl carbamate in alcoholic beverages.  

PubMed

A sensitive and rapid analytical methodology based on derivatization followed by gas chromatography-mass spectrometry (GC-MS) was developed for the quantitative determination of the toxic contaminant ethyl carbamate (EC, urethane, C(2)H(5)OCONH(2)) in alcoholic samples. EC was extracted using liquid-liquid extraction technique, and then silylated with bis-(trimethylsilyl)trifluoroacetamide, analysed finally by GC-MS. The isopropyl carbamate was used as the internal standard for quantitative analysis of EC in alcoholic samples. In this work, the sample extraction and derivatization reaction conditions were investigated, and the optimal extraction conditions obtained were: pH 9 and solvent of ethyl acetate, and the derivatization conditions were: derivatization reaction temperature of 80C and time duration of 30 min. With the optimal conditions, the method validations were also studied. In the validation studies, EC exhibited good linearity with a regression coefficient of 0.9999. The limit of detection and limit of quantification were 0.30 and 5.0 ?g/kg, respectively. The precision was less than 8.4%. Finally, the proposed technique was successfully applied to the analysis of EC in 35 kinds of alcoholic samples. The experimental results have demonstrated that the proposed technique is a fast, reliable and low-cost method for determination of EC in alcoholic samples. PMID:22383421

Xu, Xuejiao; Gao, Yihan; Cao, Xiujun; Wang, Xiang; Song, Guoxin; Zhao, Jianfeng; Hu, Yaoming

2012-04-01

76

Determination of free and ethoxylated alkylphenols in leather with gas chromatography-mass spectrometry.  

PubMed

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

Ma, He-Wei; Cheng, Ya

2010-12-10

77

The gas chromatography/mass spectrometry can be used for dose estimation in irradiated pork  

NASA Astrophysics Data System (ADS)

Food safety can be improved using ionizing radiation to reduce food spoilage and to extend its shelf life. The gas chromatography/mass spectrometry (GC/MS) has been validated by the European Community as a powerful method to identify irradiated food containing fat. The preliminary goals of our research were: (i) to set up this method, based on the detection of radiation induced 2-dodecylcyclobutanones (2-DCB) in pork muscle samples and (ii) to check the microbiological efficacy of the treatment. The main objective was to render the GC/MS a quantitative technique for dose estimation, through the measurement of the 2-DCB concentration in the irradiated sample. Our results show that the reduction of the microbial population is substantially reduced even at 2 kGy, and that a clear identification of irradiated samples can be achieved also one month after irradiation at 2 kGy in frozen-stored samples. The 2-DCB concentration showed a linear dependence on dose in the range 1-10 kGy, no matter the origin of the sample; a unique calibration function was obtained, that allowed dose estimation in irradiated pork samples. A retrospective evaluation on the quality of the treatment could be carried out this way.

D'Oca, M. C.; Bartolotta, A.; Cammilleri, M. C.; Giuffrida, S. A.; Parlato, A.; Di Noto, A. M.; Caracappa, S.

2009-07-01

78

APPLICATIONS OF INFORMATION THEORY AND PATTERN RECOGNITION TO GAS CHROMATOGRAPHY-MASS SPECTROMETRIC ANALYSIS OF TOXIC ORGANIC COMPOUNDS IN AMBIENT AIR  

EPA Science Inventory

The number of information channels contained in the gas chromatographic, mass spectrometric, and combined gas chromatography-mass spectrometric analysis of 78 toxic organic compounds has been determined. The toxic compounds are those routinely monitored in ambient air samples usi...

79

Retrospective identification of chemical warfare agents by high-temperature automatic thermal desorptiongas chromatographymass spectrometry  

Microsoft Academic Search

An automated thermal desorption (ATD)gas chromatographymass spectrometry method was developed for the analysis of selected chemical warfare (CW) agents. Suitable methods were developed for analytes of high volatility to low volatility. The less volatile CW agents required the purchase and installation of a high-temperature valve upgrade kit allowing valve temperatures of up to 260C to be reached. The limit of

Wendy A. Carrick; David B. Cooper; Bob Muir

2001-01-01

80

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

Microsoft Academic Search

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

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

2012-01-01

81

Gas Chromatography?Mass Spectrometry?Basic Principles, Instrumentation and Selected Applications for Detection of Organic Compounds  

Microsoft Academic Search

This mini?review discusses the analytical technique of gas chromatography?mass spectrometry (GC?MS), specifically basic principles and instrumentations. The applications of GC?MS to a number of studies for determining organic compounds from around the world are presented and highlight its universal use and acceptance. Selected applications show that GC?MS is an integral and complimentary part of many field studies involving organic compound

J. Sneddon; S. Masuram; J. C. Richert

2007-01-01

82

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

Microsoft Academic Search

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 500C for 4 s with TMAH. The core pyrogram revealed peaks retaining the structural attributes

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

2002-01-01

83

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

Microsoft Academic Search

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

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

1998-01-01

84

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

Microsoft Academic Search

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 liquidliquid extraction procedure. The clean-up procedure is performed using an acid solution. Papaverine is used as

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

2000-01-01

85

Development and validation of a gas chromatographymass spectrometry assay for opiates and cocaine in human teeth  

Microsoft Academic Search

A procedure based on gas chromatographymass spectrometry (GCMS) 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 37C for 18h. Then, after pH adjustment to 6, and the analytes were extracted with two volumes

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

2006-01-01

86

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

Microsoft Academic Search

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

Huabo Duan; Jinhui Li; Jyh-Feng Hwang; Wang Chen; Elisabeth Gilmore; Peter Adams; Lester Lave; Weifeng Jia; Violeta Mugica; Sara Hernandez; Miguel Torres; Rocio Garca; Antton Melendez; Estibaliz Garca; 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

87

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

PubMed Central

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

Arora, Pankaj Kumar

2014-01-01

88

Nitrate Reduction in a Groundwater Microcosm Determined by 15N Gas Chromatography-Mass Spectrometry  

PubMed Central

Aerobic and anaerobic groundwater continuous-flow microcosms were designed to study nitrate reduction by the indigenous bacteria in intact saturated soil cores from a sandy aquifer with a concentration of 3.8 mg of NO3?-N liter?1. Traces of 15NO3? were added to filter-sterilized groundwater by using a Darcy flux of 4 cm day?1. Both assimilatory and dissimilatory reduction rates were estimated from analyses of 15N2, 15N2O, 15NH4+, and 15N-labeled protein amino acids by capillary gas chromatography-mass spectrometry. N2 and N2O were separated on a megabore fused-silica column and quantified by electron impact-selected ion monitoring. NO3? and NH4+ were analyzed as pentafluorobenzoyl amides by multiple-ion monitoring and protein amino acids as their N-heptafluorobutyryl isobutyl ester derivatives by negative ion-chemical ionization. The numbers of bacteria and their [methyl-3H]thymidine incorporation rates were simultaneously measured. Nitrate was completely reduced in the microcosms at a rate of about 250 ng g?1 day?1. Of this nitrate, 80 to 90% was converted by aerobic denitrification to N2, whereas only 35% was denitrified in the anaerobic microcosm, where more than 50% of NO3? was reduced to NH4+. Assimilatory reduction was recorded only in the aerobic microcosm, where N appeared in alanine in the cells. The nitrate reduction rates estimated for the aquifer material were low in comparison with rates in eutrophic lakes and coastal sediments but sufficiently high to remove nitrate from an uncontaminated aquifer of the kind examined in less than 1 month. PMID:16348048

Bengtsson, Gran; Annadotter, Helne

1989-01-01

89

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

PubMed Central

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

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

2013-01-01

90

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

PubMed Central

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) g/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) g/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

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

2009-01-01

91

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

SciTech Connect

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

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

1994-05-01

92

Comprehensive drug screening by integrated use of gas chromatography/mass spectrometry and Remedi HS.  

PubMed

The authors evaluated an integrated approach for the screening of drugs in biosamples consisting of gas chromatography/mass spectrometry analysis of serum or whole blood (SB/GC-MS) and of high-performance liquid chromatographic and ultraviolet (HPLC-UV) analysis of urine with the REMEDi HS Biorad system (U/REM) (Bio-rad; Segrate, MI, Italy). Urine and blood samples from 26 suspected intoxicated patients and from 22 suspected lethal poisoning cases were examined. Eighty-one of the 99 parent drugs/main metabolites detected were identified by SB/GC-MS and 54 with U/REM. Thirty-six drugs/metabolites were identified with both methods, 45 by SB/GC-MS alone, and 18 by U/REM alone. Absence of the mass spectrometry (MS) spectra in the reference library and high polarity of the analytes were the main reasons for failed identification by SB/GC-MS. Unsuccessful identifications with U/REM were basically caused by the absence of the UV spectra in the reference library or by low chromatographic and spectroscopic selectivity as in the case of barbiturates and benzodiazepines (BZD), which represented 11% and 51%, respectively, of the 45 SB/GC-MS unique identifications. Urine samples of 14 BZD-positive cases were also submitted to enzymatic hydrolysis and analyzed with the REMEDi UBz assay, and results were compared with those obtained by SB/GC-MS: 14 of the 22 identified BZD were detected with both methods, three by U/REM only, and five by SB/GC-MS only. In conclusion, the integrated use of SB/GC-MS and U/REM approaches greatly enhances the amount and quality of analytical information obtainable by applying either method alone. PMID:11360040

Valli, A; Polettini, A; Papa, P; Montagna, M

2001-06-01

93

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

PubMed

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

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

2012-05-01

94

Pyrolysis-high resolution gas chromatography and pyrolysis gas chromatography-mass spectrometry of kerogens and kerogen precursors  

NASA Technical Reports Server (NTRS)

A series of kerogens and kerogen precursors isolated from DSDP samples, oil shales and recent algal mats have been examined by Curie point pyrolysis-high resolution gas chromatography and gas chromatography-mass spectrometry. This study has shown that the three main types of kerogens (marine, terrestrial and mixtures of both) can be characterized using these techniques. The marine (algal) kerogens yield principally aliphatic products and the terrestrial kerogens yield more aromatic and phenolic products with some n-alkanes and n-alkenes. The yields of n-alkanes and n-alkenes increase and phenols decrease with increasing geologic age, however, pyrolysis-GC cannot be used to characterize the influence of short term diagenesis on the kerogen structure.

Van De Meent, D.; Brown, S. C.; Philp, R. P.; Simoneit, B. R. T.

1980-01-01

95

Extending the range of compounds amenable for gas chromatography-mass spectrometric analysis.  

PubMed

Gas chromatography-mass spectrometry (GC-MS) suffers from a major limitation in that an expanding number of thermally labile or low volatility compounds of interest are not amenable for analysis. We found that the elution temperatures of compounds from GC can be significantly lowered by reducing the column length, increasing the carrier gas flow rate, reducing the capillary column film thickness and lowering the temperature programming rate. Pyrene is eluted at 287 degrees C in standard GC-MS with a 30 m x 0.25 mm I.D. column with 1-microm DB5ms film and 1-ml/min He column flow rate. In contrast, pyrene is eluted at 79 degrees C in our "Supersonic GC-MS" system using a 1 m x 0.25 mm I.D. column with 0.1-microm DB5ms film and 100-ml/min He column flow rate. A simple model has been invoked to explain the significantly (up to 208 degrees C) lower elution temperatures observed. According to this model, every halving of the temperature programming rate, or number of separation plates (either through increased flow rate or due to reduced column length), results in approximately 20 degrees C lower elution temperature. These considerably lower elution temperatures enable the analysis of an extended range of thermally labile and low volatility compounds, that otherwise could not be analyzed by standard GC-MS. We demonstrate the analysis of large polycyclic aromatic hydrocarbons (PAHs) such as decacyclene with ten fused rings, well above the current GC limit of PAHs with six rings. Even a metalloporphirin such as magnesiumoctaethylporphin was easily analyzed with elution temperatures below 300 degrees C. Furthermore, a range of thermally labile compounds were analyzed including carbamates such as methomyl, aldicarb, aldicarbsulfone and oxamyl, explosives such as pentaerythritol tetranitrate, Tetryl and HMX, and drugs such as reserpine (608 a.m.u.). Supersonic GC-MS was used, based on the coupling of a supersonic molecular beam (SMB) inlet and ion sources with a bench-top Agilent 6890 GC plus 5972 MSD. The Supersonic GC-MS provides enhanced molecular ion without any ion source related peak tailing. Thus, the lower GC separation power involved in the analysis of thermally labile and low volatility compounds is compensated by increased separation power of the MS gained from the enhanced molecular ion. Several implications of these findings are discussed, including our conclusion that slower chromatography leads to better analysis of thermally labile compounds. PMID:12741601

Fialkov, Alexander B; Gordin, Alexander; Amirav, Aviv

2003-04-01

96

Characterization of human expired breath by solid phase microextraction and analysis using gas chromatography-mass spectrometry and differential mobility spectrometry  

E-print Network

Breath analysis has potential to become a new medical diagnostic modality. In this thesis, a method for the analysis of human expired breath was developed using gas chromatography-mass spectroscopy. It was subsequently ...

Merrick, William (William F. W.)

2005-01-01

97

Adsorption of OrganicAcidsfromAmnioticFluidandUrineonto SilicaGel beforeAnalysisbyGasChromatography andCombined Gas Chromatography\\/Mass Spectrometry  

Microsoft Academic Search

We describe a method for adsorbing organic acids from amniotic fluid and urine specimens onto a column of silica gel before analysis by gas chromatography and by com- bined gas chromatography\\/mass spectrometry. Analytical recoveries of individual organic acids by our adsorption method compare favorably with those obtained by a more laborious manual extraction with ethyl acetate. Results for specimens of

Vincent P. Williams; Dexter K. Ching

98

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

EPA Science Inventory

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

99

Analytical strategies for characterizing organic paint media using gas chromatography/mass spectrometry.  

PubMed

Throughout history, artists have experimented with a variety of organic-based natural materials, using them as paint binders, varnishes, and ingredients for mordants in gildings. Artists often use many layers of paint to produce particular effects. How we see a painting is thus the final result of how this complex, highly heterogeneous, multimaterial, and multilayered structure interacts with light. The chemical characterization of the organic substances in paint materials is of great importance for artwork conservation because the organic components of the paint layers are particularly subject to degradation. In addition, understanding the organic content and makeup of paint materials allows us to differentiate between the painting techniques that have been used over history. Applying gas chromatography/mass spectrometry (GC/MS) analysis to microsamples of paint layers is widely recognized as the best approach for identifying organic materials, such as proteins, drying oils, waxes, terpenic resins, and polysaccharide gums. The method provides essential information for reconstructing artistic techniques, assessing the best conditions for long-term preservation, and planning restoration. In this Account, we summarize the more common approaches adopted in the study of the organic components of paint materials. Our progress in developing GC/MS analytical procedures in the field of cultural heritage is presented, focusing on problems that arise from (i) the presence of mixtures of many chemically complex and degraded materials, (ii) the interference of inorganic species, (iii) the small size of the samples, and (iv) the risk of contamination. We outline some critical aspects of the analytical strategy, such as the need to optimize specific wet-chemical sample pretreatments in order to separate the various components, hydrolyze macromolecular analytes, clean-up inorganic ions, and derivatize polar molecules for subsequent GC/MS separation and identification. We also discuss how to interpret the chromatographic data so as to be able to identify the materials. This identification is based on the presence of specific biomarkers (chemotaxonomy), on the evaluation of the overall chromatographic profile, or on the quantitative analysis of significant compounds. GC/MS-based analytical procedures have for 20 years provided important contributions to conservation science, but challenges and opportunities still coexist in the field of organic-based paint materials. We give selected examples and provide case studies showing how a better understanding of the chemical composition of organic paint materials and of their degradation pathways contribute to a better knowledge our cultural heritage, and to its preservation for future generations. PMID:20180544

Colombini, Maria Perla; Andreotti, Alessia; Bonaduce, Ilaria; Modugno, Francesca; Ribechini, Erika

2010-06-15

100

Plasma metabolomic profiling of dairy cows affected with ketosis using gas chromatography/mass spectrometry  

PubMed Central

Background Ketosis is an important problem for dairy cows` production performance. However, it is still little known about plasma metabolomics details of dairy ketosis. Results A gas chromatography/mass spectrometry (GC/MS) technique was used to investigate plasma metabolic differences in cows that had clinical ketosis (CK, n=22), subclinical ketosis (SK, n=32), or were clinically normal controls (NC, n=22). The endogenous plasma metabolome was measured by chemical derivatization followed by GC/MS, which led to the detection of 267 variables. A two-sample t-test of 30, 32, and 13 metabolites showed statistically significant differences between SK and NC, CK and NC, and CK and SK, respectively. Orthogonal signal correction-partial least-square discriminant analysis (OPLS-DA) revealed that the metabolic patterns of both CK and SK were mostly similar, with the exception of a few differences. The development of CK and SK involved disturbances in many metabolic pathways, mainly including fatty acid metabolism, amino acid metabolism, glycolysis, gluconeogenesis, and the pentose phosphate pathway. A diagnostic model arbitrary two groups was constructed using OPLS-DA and receiveroperator characteristic curves (ROC). Multivariate statistical diagnostics yielded the 19 potential biomarkers for SK and NC, 31 for CK and NC, and 8 for CK and SK with area under the curve (AUC) values. Our results showed the potential biomarkers from CK, SK, and NC, including carbohydrates, fatty acids, amino acids, even sitosterol and vitamin E isomers, etc. 2-piperidinecarboxylic acid and cis-9-hexadecenoic acid were closely associated with metabolic perturbations in ketosis as Glc, BHBA and NEFA for dealing with metabolic disturbances of ketosis in clinical practice. However, further research is needed to explain changes of 2,3,4-trihydroxybutyric acid, 3,4-dihydroxybutyric acid, ?-aminobutyric acid, methylmalonic acid, sitosterol and ?-tocopherol in CK and SK, and to reveal differences between CK and SK. Conclusion Our study shows that some new biomarkers of ketosis from plasma may find new metabolic changes to have clinically new utility and significance in diagnosis, prognosis, and prevention of ketosis in the future. PMID:24070026

2013-01-01

101

Detecting Organic Compounds in Martian Soil Analogues Using Gas Chromatography Mass Spectrometry  

NASA Technical Reports Server (NTRS)

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.

Glavin, D. P.; Buch, A.; Mahaffy, P. R.

2004-01-01

102

Multiresidue analysis of pollutants as their trimethylsilyl derivatives, by gas chromatography-mass spectrometry.  

PubMed

This paper reports a multiresidue analysis procedure which permits the identification and quantification of sixty-three water-soluble pollutants. Subsequent to their solid-phase extraction (SPE) enrichment, analyses of species have been carried out from one solution, by a single injection, as their trimethylsilyl-oxime ether/ester derivatives, by gas chromatography-mass spectrometry, within 31min. Based on our optimized extraction, derivatization and mass fragmentation studies separation have been performed in the total ion current mode, identification and quantification of compounds have been carried out on the basis of their selective fragment ions. Including various pharmaceuticals, benzoic acid, its substituted species, different aromatic carboxylic acids, cholic acids, unsaturated and saturated fatty acids, aliphatic dicarboxylic acids, as well as synthetic pollutants of various origins (2,4-di-tert-butylphenol, different phthalates). Standard compounds were added to 500 mL effluent wastewater samples, at three concentrations (1-5 microg/L, 5-10 microg/L and 10-20 microg/L). Recoveries, using the Waters Oasis cartridges performing extractions at pH 2, pH 4 and pH 7 proved to be the optimum at pH 4 (average recoveries (94.5%), except for cholesterol (10%), paracetamol (18%) and 2,5-dihydroxybenzoic acid (25%). Carbamazepine could be recovered at pH 7, only. Responses, obtained with derivatized standards proved to be linear in the range of 4-80 microg/L levels. Limit of quantitation values varied between 0.92 ng/L (4-hydroxyphenylacetic acid) and 600 ng/L (dehydrocholic acid) concentrations. One of the most important messages of this work is the confirmation of the origin of blank values. It was shown that contaminants, mainly 2,4-di-tert-butylphenol, different phthalates and fatty acids, are sourced both from the reagents and mainly from the SPE procedure, independent on the cartridge applied. Reproducibilities, characterized with the relative standard deviations (RSDs) of measurements, varied between 0.71% and 10%, with an average of 4.38% RSD. The practical utility of the method was shown by the identification and quantification of the pollutant contents of Hungarian influent and effluent wastewaters (for six consecutive months and that of the Danube River for 2 months). PMID:19201001

Sebok, A; Vasanits-Zsigrai, A; Helenkr, A; Zray, Gy; Molnr-Perl, I

2009-03-20

103

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

PubMed

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

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

2005-12-01

104

Authentication of Organically and Conventionally Grown Basils by Gas Chromatography/Mass Spectrometry Chemical Profiles  

PubMed Central

Basil plants cultivated by organic and conventional farming practices were accurately classified by pattern recognition of gas chromatography/mass spectrometry (GC/MS) data. A novel extraction procedure was devised to extract characteristic compounds from ground basil powders. Two in-house fuzzy classifiers, i.e., the fuzzy rule-building expert system (FuRES) and the fuzzy optimal associative memory (FOAM) for the first time, were used to build classification models. Two crisp classifiers, i.e., soft independent modeling by class analogy (SIMCA) and the partial least-squares discriminant analysis (PLS-DA), were used as control methods. Prior to data processing, baseline correction and retention time alignment were performed. Classifiers were built with the two-way data sets, the total ion chromatogram representation of data sets, and the total mass spectrum representation of data sets, separately. Bootstrapped Latin partition (BLP) was used as an unbiased evaluation of the classifiers. By using two-way data sets, average classification rates with FuRES, FOAM, SIMCA, and PLS-DA were 100 0%, 94.4 0.4%, 93.3 0.4%, and 100 0%, respectively, for 100 independent evaluations. The established classifiers were used to classify a new validation set collected 2.5 months later with no parametric changes except that the training set and validation set were individually mean-centered. For the new two-way validation set, classification rates with FuRES, FOAM, SIMCA, and PLS-DA were 100%, 83%, 97%, and 100%, respectively. Thereby, the GC/MS analysis was demonstrated as a viable approach for organic basil authentication. It is the first time that a FOAM has been applied to classification. A novel baseline correction method was used also for the first time. The FuRES and the FOAM are demonstrated as powerful tools for modeling and classifying GC/MS data of complex samples and the data pretreatments are demonstrated to be useful to improve the performance of classifiers. PMID:23398171

Wang, Zhengfang; Chen, Pei; Yu, Liangli; Harrington, Peter de B.

2013-01-01

105

Rapid and sensitive method for the determination of propylene oxide in cigarette mainstream smoke by gas chromatography-mass spectrometry.  

PubMed

A rapid method using gas chromatography-mass spectrometry for the analysis of propylene oxide in cigarette mainstream smoke is reported. Validation data show the method, which requires a minimum of sample preparation, to be selective, sensitive, reliable, and robust. Propylene oxide is found in the University of Kentucky Reference Cigarettes 1R4F and 2R4F at concentrations of 0.93 and 0.65 microg/cigarette, respectively, with a quantitation limit of 0.135 microg/cigarette. PMID:16599409

Diekmann, Joerg; Douda, Michael; Rustemeier, Klaus

2006-01-01

106

A simple and reliable procedure for the determination of psychoactive drugs in oral fluid by gas chromatographymass spectrometry  

Microsoft Academic Search

A simple and reliable gas chromatographymass 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

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

2007-01-01

107

Using microwave distillation-solid-phase microextraction--gas chromatography--mass spectrometry for analyzing fish tissue.  

PubMed

A technique for the analysis of the volatile compounds from fish tissue employing microwave distillation-solid-phase microextraction-gas chromatography-mass spectrometry is described. A qualitative listing of 174 compounds observed in the headspace is given, and a quantitative method for the determination of the off-flavor contaminants (2-methylisoborneol and geosmin) is presented. Borneol and decahydro-1-naphthol are used as the surrogate and internal standards, respectively. A linear calibration curve is obtained for 0.1 to 5 ppb with a recovery level of 60% at 2.5 ppb. Comparison of the instrumental method with a human flavor checker showed good agreement. PMID:10901414

Grimm, C C; Lloyd, S W; Batista, R; Zimba, P V

2000-07-01

108

Application of capillary gas chromatography mass spectrometry/computer techniques to synoptic survey of organic material in bed sediment  

USGS Publications Warehouse

A bed sediment sample taken from an area impacted by heavy industrial activity was analyzed for organic compounds of environmental significance. Extraction was effected on a Soxhlet apparatus using a freeze-dried sample. The Soxhlet extract was fractionated by silica gel micro-column adsorption chromatography. Separation and identification of the organic compounds was accomplished by capillary gas chromatography/mass spectrometry techniques. More than 50 compounds were identified; these include saturated hydrocarbons, olefins, aromatic hydrocarbons, alkylated polycyclic aromatic hydrocarbons, and oxygenated compounds such as aldehydes and ketones. The role of bed sediments as a source or sink for organic pollutants is discussed. ?? 1981.

Steinheimer, T.R.; Pereira, W.E.; Johnson, S.M.

1981-01-01

109

PRECISION AND ACCURACY IN THE DETERMINATION OF ORGANICS IN WATER BY FUSED SILICA CAPILLARY COLUMN GAS CHROMOTOGRAPHY/MASS SPECTROMETRY AND PACKED COLUMN GAS CHROMATOGRAPHY/MASS SPECTROMETRY  

EPA Science Inventory

Two general methods for the identification and measurement of organic compounds in water are compared. One method employs packed column chromatography and the other fused silica capillary column chromatography. The two gas chromatography/mass spectrometry (GC/MS) methods use diff...

110

Assay of blood and tissue oxaloacetate and alpha-ketoglutarate by isotope dilution gas chromatography-mass spectrometry.  

PubMed

The assay of oxaloacetate and alpha-ketoglutarate in biological samples is complicated by their chemical instability and low concentrations. We present a quantitative assay for physiological concentrations of these metabolites by isotope dilution gas chromatography-mass spectrometry. Samples are spiked with the corresponding internal standards of [U-13C4]oxaloacetate and [U-13C5] alpha-ketoglutarate prior to their treatment with hydroxylamine. After ethyl acetate extraction and evaporation of the organic phases, the oximes are converted to t-butyldimethylsilyl ethers and analyzed by selected ion monitoring gas chromatography-mass spectrometry of the [M-57]+ ion in electron impact. Although the internal standards of [U-13C4]oxaloacetate and [U-13C5] alpha-ketoglutarate are not commercially available, they can easily be synthesized in 30 min by reacting [1,2,3,6-13C4]citrate with citrate lyase, and L-[U-13C5]glutamate with pyruvate and glutamate-pyruvate transaminase, respectively. Because of their chemical instability, the internal standards are prepared on the day of the analysis. A stock solution of [1,2,3,6-13C4]citrate is prepared from L-[U-13C4]aspartate using citrate synthase and glutamate-oxaloacetate transaminase and then purified and kept frozen until required. The detection limit of the method is 0.05 nmol in a given sample. The method was applied to measurements of oxaloacetate and alpha-ketoglutarate in human blood and rat liver. PMID:7733461

Laplante, A; Comte, B; Des Rosiers, C

1995-01-20

111

Automated determination of carboxyhemoglobin contents in autopsy materials using head-space gas chromatography/mass spectrometry.  

PubMed

To establish a method for the routine analysis of carboxyhemoglobin (COHb) in autopsy materials including those which have undergone postmortem changes, e.g. thermo-coagulation, putrifaction and contamination, an automated head-space gas chromatography/mass spectrometry (GC/MS) analysis was utilized. The procedure consisted of preparation of the sample in a vial and a carbon monoxide (CO) saturated sample, for estimation of hemoglobin content, in another vial, the addition of n-octanol, potassium ferricyanide and an internal standard (t-butanol), GC separation and determination of CO using a GC/MS system equipped with an automated head-space gas sampler. The method was practical not only with the blood and bone marrow aspirates to confirm the findings on the CO-oximeter system, but also with the thermo-coagulated and putrified blood. PMID:10978651

Oritani, S; Zhu, B L; Ishida, K; Shimotouge, K; Quan, L; Fujita, M Q; Maeda, H

2000-09-11

112

Analysis of kerogens by pyrolysis-gas chromatography-mass spectrometry using selective ion monitoring. III. Long-chain alkylbenzenes  

NASA Astrophysics Data System (ADS)

Analysis of the 3 principal kerogen types by pyrolysis-gas chromatography-mass spectrometry (P-GC-MS) has been undertaken using the mass spectrometer as a selective ion detector. By monitoring the fragment ions with {m}/{e} values of 91, 105 and 119 information has been obtained concerning differences in the content of long-chain alkylbenzenes in the kerogen pyrolysates, thus implying differences in the kerogen structures. Simulated maturation of the kerogens followed by specific ion ( {m}/{e} 105) gas chromatographic-mass spectrometric (GC-MS) analysis of the extracted liquid products, and specific ion ( {m}/{e} 105) GC-MS analysis of 3 crude oils is also described. The use of long-chain alkylbenzenes for geochemical correlation studies is discussed.

Solli, H.; Larter, S. R.; Douglas, A. G.

113

Differentiation of the volatile profile of microbiologically contaminated canned tomatoes by dynamic headspace extraction followed by gas chromatographymass spectrometry analysis  

Microsoft Academic Search

The aromatic profile of microbiologically contaminated canned tomatoes was analyzed by the dynamic headspace extraction technique coupled with gas chromatographymass spectrometry. Canned tomatoes contaminated with Escherichia coli, Saccharomyces cerevisiae and Aspergillus carbonarius were analyzed after 2 and 7 days. About 100 volatiles were detected, among which alcohols, aldehydes and ketones were the most abundant compounds. Gas chromatographic peak areas were

F. Bianchi; M. Careri; A. Mangia; M. Mattarozzi; M. Musci; I. Concina; M. Falasconi; E. Gobbi; M. Pardo; G. Sberveglieri

2009-01-01

114

Volatile constituents of Murraya koenigii fresh leaves using headspace solid phase microextraction--gas chromatography-mass spectrometry.  

PubMed

The volatile components of Murraya koenigii fresh leaves, collected from Surat Thani province, Thailand were studied by using headspace (HS) solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS). The four fibers employed to extract the volatiles were polydimethylsiloxane (PDMS), polydimethylsiloxane-divinylbenzene (PDMS-DVB), carboxane-polydimethylsiloxane (CAR-PDMS) and polydimethylsiloxane-divinylbenzene-carboxane (PDMS-DVB-CAR). The volatile constituents of M. koenigii fresh leaves were also extracted by hydrodistillation and analyzed by GC-MS. Fifty-one compounds were identified by these fibers. Five major compounds, ?-terpinene, ?-caryophyllene, ?-phellandrene, a-selinene and a-pinene, were detected in all fibers. The PDMS-DVB-CAR fiber was considered as the best for trapping key volatiles of M. koenigii fresh leaves. PMID:25632485

Sukkaew, Sayamol; Pripdeevech, Patcharee; Thongpoon, Chalermporn; Machan, Theeraphan; Wongchuphan, Rattana

2014-12-01

115

Gas chromatography mass spectrometry of JWH-018 metabolites in urine samples with direct comparison to analytical standards  

PubMed Central

JWH-018 (1-pentyl-3-(1-naphthoyl)indole) is one of numerous potential aminoalkylindoles contained in products marketed as K2 or Spice. Investigation of the urinary metabolites from consumption of these compounds is important because they are banned in the United States and many European countries. An efficient extraction procedure and gas chromatography mass spectrometry (GC-MS) method were developed for detection of K2 metabolites in urine from individuals suspected of using these products. Analytical standards were used to elucidate the structure-specific mass spectral fragmentations and retention properties to confirm proposed identifications and support quantitative studies. A procedure for the synthesis of one of these metabolites (5-hydroxypentyl JWH-018) was also developed. Results are comparable to existing LC-MS/MS methods, with the same primary metabolites detected. The specific metabolite hydrolysis products include 4-hydroxpentyl, 5-hydroxypentyl, and N-pentanoic acid derivatives. PMID:23683902

Emerson, Beth; Durham, Bill; Gidden, Jennifer; Lay, Jackson O.

2013-01-01

116

Headspace Single-Drop Microextraction Gas Chromatography Mass Spectrometry for the Analysis of Volatile Compounds from Herba Asari  

PubMed Central

A rapid headspace single-drop microextraction gas chromatography mass spectrometry (SDME-GC-MS) for the analysis of the volatile compounds in Herba Asari was developed in this study. The extraction solvent, extraction temperature and time, sample amount, and particle size were optimized. A mixed solvent of n-tridecane and butyl acetate (1?:?1) was finally used for the extraction with sample amount of 0.750?g and 100-mesh particle size at 70C for 15?min. Under the determined conditions, the pound samples of Herba Asari were directly applied for the analysis. The result showed that SDME-GCMS method was a simple, effective, and inexpensive way to measure the volatile compounds in Herba Asari and could be used for the analysis of volatile compounds in Chinese medicine. PMID:23607049

Wang, Guan-Jie; Tian, Li; Fan, Yu-Ming; Qi, Mei-Ling

2013-01-01

117

Analysis of volatile components in a Chinese fish sauce, Fuzhou Yulu, by gas chromatography-mass spectrometry*  

PubMed Central

Volatile components of Fuzhou Yulu, a Chinese fish sauce, were analyzed by gas chromatography-mass spectrometry (GC-MS), and two pretreatment methods, i.e., purge and trap (P&T) GC-MS and ethyl acetate extraction followed by GC-MS, were compared. P&T-GC-MS method determined 12 components, including sulfur-containing constituents (such as dimethyl disulfide), nitrogen-containing constituents (such as pyrazine derivatives), aldehydes and ketones. Ethyl acetate extraction followed by GC-MS method detected 10 components, which were mainly volatile organic acids (such as benzenepropanoic acid) and esters. Neither of the two methods detected alcohols or trimethylamine. This study offers an important reference to determine volatile flavor components of traditional fish sauce through modern analysis methods. PMID:19067466

Yang, Yuan-fan; Chen, Shen-ru; Ni, Hui; Ye, Xing-qian

2008-01-01

118

Monitoring of bacterial sugars and hydroxy Fatty acids in dust from air conditioners by gas chromatography-mass spectrometry.  

PubMed

Bacterial levels in dust collected from hospital air-conditioning filters were examined by chemical analysis (without prior culture). The dust was analyzed by gas chromatography-mass spectrometry after hydrolysis and derivatization. l-Glycero-d-mannoheptose and hydroxy fatty acids (3-OH 12:0 and 3-OH 14:0) (primarily found in lipopolysaccharide) and muramic acid (a chemical marker for bacterial peptidoglycan) were present at higher levels in dust collected from filters primarily contacting outdoor (as opposed to indoor) air. The ratio of l-glycero-d-mannoheptose to muramic acid in dust (compared with those of a group of gram-positive and gram-negative bacteria) suggested that both dust types contained appreciable numbers of gram-negative bacteria. There is potential for the chemical assessment of the microbial content of airborne dust. PMID:16349134

Fox, A; Rosario, R M; Larsson, L

1993-12-01

119

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

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

120

Rapid determination of quetiapine in blood by gas chromatography-mass spectrometry. Application to post-mortem cases.  

PubMed

A simple, fast and sensitive method for the determination of quetiapine in human blood has been developed and validated. The method involved a basic liquid-liquid extraction procedure and subsequent analysis by gas chromatography-mass spectrometry, previous derivatization with bis(trimethylsilyl)-trifluoro-acetamide and chorotrimethylsilane (99 : 1). The methods of validation included linearity with a correlation coefficient?>?0.99 over the range 0.02-1?g?ml(-1), intra- and interday precision (always?

Lpez-Guarnido, Olga; Tabernero, Mara Jess; Hernndez, Antonio F; Rodrigo, Lourdes; Bermejo, Ana M

2014-10-01

121

Ink Dating Using Thermal Desorption and Gas Chromatography/Mass Spectrometry: Comparison of Results Obtained in Two Laboratories.  

PubMed

An ink dating method based on solvent analysis was recently developed using thermal desorption followed by gas chromatography/mass spectrometry (GC/MS) and is currently implemented in several forensic laboratories. The main aims of this work were to implement this method in a new laboratory to evaluate whether results were comparable at three levels: (i) validation criteria, (ii) aging curves, and (iii) results interpretation. While the results were indeed comparable in terms of validation, the method proved to be very sensitive to maintenances. Moreover, the aging curves were influenced by ink composition, as well as storage conditions (particularly when the samples were not stored in "normal" room conditions). Finally, as current interpretation models showed limitations, an alternative model based on slope calculation was proposed. However, in the future, a probabilistic approach may represent a better solution to deal with ink sample inhomogeneity. PMID:25389038

Koenig, Agns; Bgler, Jrgen; Kirsch, Dieter; Khler, Fritz; Weyermann, Cline

2014-11-12

122

Gas chromatography-mass spectrometry of JWH-018 metabolites in urine samples with direct comparison to analytical standards.  

PubMed

JWH-018 (1-pentyl-3-(1-naphthoyl)indole) is one of numerous potential aminoalkylindoles contained in products marketed as 'K2' or 'Spice'. Investigation of the urinary metabolites from consumption of these compounds is important because they are banned in the United States and many European countries. An efficient extraction procedure and gas chromatography-mass spectrometry (GC-MS) method were developed for detection of 'K2' metabolites in urine from individuals suspected of using these products. Analytical standards were used to elucidate the structure-specific mass spectral fragmentations and retention properties to confirm proposed identifications and support quantitative studies. A procedure for the synthesis of one of these metabolites (5-hydroxypentyl JWH-018) was also developed. Results are comparable to existing LC-MS/MS methods, with the same primary metabolites detected. The specific metabolite hydrolysis products include 4-hydroxpentyl, 5-hydroxypentyl, and N-pentanoic acid derivatives. PMID:23683902

Emerson, Beth; Durham, Bill; Gidden, Jennifer; Lay, Jackson O

2013-06-10

123

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

PubMed

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

Rajiv, P; Rajeshwari, Sivaraj; Venckatesh, Rajendran

2013-12-01

124

Pyrolysis-gas chromatography/mass spectrometry analyses of biological particulates collected during recent space shuttle missions.  

PubMed

Biological particulates collected on air filters during shuttle missions (STS-40 and STS-42) were identified using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). A method was developed for identifying the atmospheric particles and their sources through the analysis of standard materials and the selection of "marker" compounds specific to the particle type. Pyrolysis spectra of biological standards were compared with those of airborne particles collected during two space shuttle missions; marker compounds present in the shuttle particle spectra were matched with those of the standards to identify the source of particles. Particles of 0,5--1-mm diameter and weighing as little as 40 micrograms could be identified using this technique. The Py-GC/MS method identified rat food and soilless plant-growth media as two sources of particles collected from the shuttle atmosphere during flight. PMID:11536649

Matney, M L; Limero, T F; James, J T

1994-09-15

125

Determination of ametryn herbicide by bioassay and gas chromatography-mass spectrometry in analysis of residues in drinking water.  

PubMed

A simple, rapid and quantitative bioassay method was compared to a gas chromatography/mass spectrometry (GC/MS) procedure for the analysis of ametryn in surface and groundwater. This method was based on the activity of ametryn in inhibiting the growth of the primary root and shoot of germinating letuce, Lactuca sativa L. seed. The procedure was sensitive to 0.01 microgram/l and was applicable from this concentration up to 0.6 microgram/l. Initial surface sterilization of the seed, selection of pregerminated seed of certain root lengths and special equipment are not necessary. So, we concluded that the sensitivity of the bioassay method is compatible with the chromatographic method (GC-MS). However, the study of the correlation between methods suggests that the bioassay should be used only as a screening technique for the evaluation of ametryn residues in water. PMID:10464973

Queiroz, R H; Lanchote, V L; Bonato, P S; Tozato, E; de Carvalho, D; Gomes, M A; Cerdeira, A L

1999-06-01

126

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

SciTech Connect

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 /sup 15/N,/sup 13/C-alachlor and /sup 2/H/sub 5/-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.

Huang, L.Q.

1989-03-01

127

A new extraction technique for in situ analyses of amino and carboxylic acids on Mars by gas chromatography mass spectrometry  

NASA Astrophysics Data System (ADS)

In order to target key organic compounds in the Martian regolith using gas chromatography mass spectrometry (GC-MS), we have developed a new extraction procedure coupled with chemical derivatization. This new technique was tested on a Mars analog soil sample collected from the Atacama Desert in Chile. We found that amino and carboxylic acids can be extracted from the Atacama soil in a 1:1 mixture of isopropanol and water after ultrasonic treatment for 30 min. The extracted organic compounds were then derivatized in a single-step reaction using N-methyl- N-( tert-butyldimethylsilyl)-trifluoroacetamide (MTBSTFA) as the silylating agent in order to transform these compounds into volatile species that can then be detected by GC-MS. We are currently developing a miniaturized reaction cell suited for spaceflight, where both organic extraction and chemical derivatization processes can take place in a single step.

Buch, A.; Glavin, D. P.; Sternberg, R.; Szopa, C.; Rodier, C.; Navarro-Gonzlez, R.; Raulin, F.; Cabane, M.; Mahaffy, P. R.

2006-12-01

128

Electron ionization and atmospheric pressure photochemical ionization in gas chromatography-mass spectrometry analysis of amino acids.  

PubMed

The mass spectra of tert-butyldimethylsilyl (TBDMS) derivatives of 17 amino acids were obtained using electron ionization (EI) and atmospheric pressure photochemical ionization (APPhCI) mass spectrometry. The APPhCI mass spectra for all of the derivatives except arginine were shown to consist of only molecular [M](+.) and quasimolecular [MH](+) ions whereas, in the case of EI, the compounds in question underwent a drastic fragmentation. The application of APPhCI to gas chromatography-mass spectrometry enables a reliable identification of the TBDMS derivatives of amino acids in a mixture, even if its components are only partially resolved, due to the unique molecular masses for each compound. Comparison of the respective positive-ion chemical ionization (PICI) mass spectra available in the literature with APPhCI spectra has shown that, in the case of PICI, unlike APPhCI, noticeable fragmentation occurs. PMID:14624019

Revelsky, Igor A; Yashin, Yuri S; Sobolevsky, Tim G; Revelsky, Alexander I; Miller, Barbara; Oriedo, Vincent

2003-01-01

129

Pyrolysis-gas chromatography/mass spectrometry analyses of biological particulates collected during recent space shuttle missions  

NASA Technical Reports Server (NTRS)

Biological particulates collected on air filters during shuttle missions (STS-40 and STS-42) were identified using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). A method was developed for identifying the atmospheric particles and their sources through the analysis of standard materials and the selection of "marker" compounds specific to the particle type. Pyrolysis spectra of biological standards were compared with those of airborne particles collected during two space shuttle missions; marker compounds present in the shuttle particle spectra were matched with those of the standards to identify the source of particles. Particles of 0,5--1-mm diameter and weighing as little as 40 micrograms could be identified using this technique. The Py-GC/MS method identified rat food and soilless plant-growth media as two sources of particles collected from the shuttle atmosphere during flight.

Matney, M. L.; Limero, T. F.; James, J. T.

1994-01-01

130

A gas chromatography-mass spectrometry-based metabolomic approach for the characterization of goat milk compared with cow milk.  

PubMed

In this work, the polar metabolite pool of commercial caprine milk was studied by gas chromatography-mass spectrometry and multivariate statistical data analysis. Experimental data were compared with those of cow milk and the discriminant analysis correctly classified milk. By the same means, differences due to heat treatments (UHT or pasteurization) on milk samples were also investigated. Results of the 2 discriminant analyses were combined, with the aim of finding the discriminant metabolites unique for each class and shared by 2 classes. Valine and glycine were specific to goat milk, talose and malic acid to cow milk, and hydroxyglutaric acid to pasteurized samples. Glucose and fructose were shared by cow milk and UHT-treated samples, whereas ribose was shared by pasteurized and goat milk. Other discriminant variables were not attributed to specific metabolites. Furthermore, with the aim to reduce food fraud, the issue of adulteration of caprine milk by addition of cheaper bovine milk has been also addressed. To this goal, mixtures of goat and cow milk were prepared by adding the latter in a range from 0 to 100% (vol/vol) and studied by multivariate regression analysis. The error in the level of cow milk detectable was approximately 5%. These overall results demonstrated that, through the combined approach of gas chromatography-mass spectrometry and multivariate statistical data analysis, we were able to discriminate between milk typologies on the basis of their polar metabolite profiles and to propose a new analytical method to easily discover food fraud and to protect goat milk uniqueness. The use of appropriate visualization tools improved the interpretation of multivariate model results. PMID:25108860

Scano, Paola; Murgia, Antonio; Pirisi, Filippo M; Caboni, Pierluigi

2014-10-01

131

Quantitative determination of a new anticonvulsant (CGS 18416A) in human plasma using capillary gas chromatography/mass spectrometry.  

PubMed

An analytical method has been developed for the determination of a new antiepileptic drug, CGS 18416A, in human plasma. CGS 18416A is a new anticonvulsant representative of a novel class of water-soluble agents being developed for the treatment of epilepsy. Preclinical trials indicate sustained efficacy at relatively low oral doses, indicating a need for a sensitive assay. The method is based on capillary gas chromatography/mass spectrometry and utilizes stable isotope-labelled CGS 18416A as the internal standard. Samples (1 mL) are acidified, then washed with pentane/ethyl acetate, followed by liquid/liquid extraction at pH 11 with pentane/ethyl acetate. Extracts are then concentrated and analysed directly by gas chromatography/mass spectrometry. Separation is accomplished on a thick film methylsilicone capillary column. Mass spectrometry was carried out under positive ion ammonia Cl conditions with selected ion monitoring of the protonated molecular ions (m/z = 248 and 252) for CGS 18416A and the 13CD3-CGS 18416A, respectively. Specificity was demonstrated by the lack of interfering peaks at the retention time of CGS 18416A and the internal standard. Recovery and reproducibility assessments indicate good accuracy and precision over the validated concentration range of 0.2-51 ng/mL. The limit of quantification is 0.2 ng/mL and the method has sufficient sensitivity to support clinical trials. This is illustrated with an example of quantification in a normal volunteer following oral dosing. PMID:1463936

Hayes, M J; Khemani, L; Leal, M; Powell, M L

1992-01-01

132

Quantitative Gas ChromatographyMass Spectrometry Isomer-Specific Measurement of Hydroxy Fatty Acids in Biological Samples and Food as a Marker of Lipid Peroxidation  

Microsoft Academic Search

We have developed a capillary gas chromatographymass spectrometry method for the quantitative analysis of individual positional isomers of monohydroxy fatty acids derived from linoleic, arachidonic, eicosapentaenoic, or docosahexaenoic acid. Peroxidation of a particular polyunsaturated fatty acid results already in a complex mixture of positional isomers of hydroperoxy and hydroxy fatty acids. Catalytic hydrogenation of lipid extracts produces stable saturated hydroxy

R. Wilson; R. Smith; P. Wilson; M. J. Shepherd; R. A. Riemersma

1997-01-01

133

Determination of off-flavor compounds, 2-methylisoborneol and geosmin, in salmon fillets using stir bar sorptive extractionthermal desorption coupled with gas chromatographymass 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...

134

Dehydration of Methylcyclohexanol Isomers in the Undergraduate Organic Laboratory and Product Analysis by Gas Chromatography-Mass Spectroscopy (GC-MS)  

ERIC Educational Resources Information Center

Dehydrations of "cis"- and "trans"-2-methylcyclohexanol mixtures were carried out with 60% sulfuric acid at 78-80 [degrees]C as a function of time and the products were identified by gas chromatography-mass spectroscopy (GC-MS) analysis. The compounds identified in the reaction mixtures include alkenes, 1-, 3-, and 4-methylcyclohexenes and

Clennan, Malgorzata M.; Clennan, Edward L.

2011-01-01

135

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...

136

Solidphase extraction and gas chromatographymass spectrometry determination of kaempferol and quercetin in human urine after consumption of Ginkgo biloba tablets  

Microsoft Academic Search

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 chromatographymass 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

D. G. Watson; E. J. Oliveira

1999-01-01

137

Lipid fatty acid profile analyses in liver and serum in rats with nonalcoholic steatohepatitis using improved gas chromatography-mass spectrometry methodology  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fatty acids (FA) are essential components of lipids and exhibit important biological functions. The analyses of FAs are routinely carried out by gas chromatography-mass spectrometry, after multi-step sample preparation. In this study, several key experimental factors were carefully examined, validat...

138

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

ERIC Educational Resources Information Center

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

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

2012-01-01

139

Spectrophotometry  

NSDL National Science Digital Library

The North Carolina Community College System BioNetwork's interactive eLearning tools (IETs) are reusable chunks of training that can be deployed in a variety of courses or training programs. IETs are designed to enhance, not replace hands-on training. Learners are able to enter a hands-on lab experience better prepared and more confident. This particular IET delves into Spectrophotometry, where visitors can practice working with a spectrophotometer by examining a sample solution at different wavelengths.

2013-08-05

140

Spectrophotometry  

NSDL National Science Digital Library

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.

Blauch, David N.

141

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

PubMed Central

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

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

2011-01-01

142

Fluoroacetylation/fluoroethylesterification as a derivatization approach for gas chromatography-mass spectrometry in metabolomics: preliminary study of lymphohyperplastic diseases.  

PubMed

Metabolic fingerprinting in combination with gas chromatography and multivariate analysis is being extensively employed for the improved understanding of biological changes induced by endogenous or exogenous factors. Chemical derivatization increases the sensitivity and specificity of gas chromatography-mass spectrometry (GC-MS) for polar or thermally labile biological compounds, which bear derivatizable groups. Thus, there is a constant demand for simple methods of derivatization and separation that satisfy the need for metabolite analysis, identifying as many chemical classes of compounds as possible. In this study, an optimized protocol of extraction and derivatization is established as a generally applicable method for the analysis of a wide range of classes of metabolites in urine, whole blood and saliva. Compounds of biological relevance bearing hydroxyl- carboxyl- and amino-groups are derivatized using single-step fluoroacetylation/fluoroethylesterification after proper optimization of the protocol. Subsequently, the developed derivatization procedure is engaged in finding blood metabolic biomarkers, induced by lymphohyperplastic disease, through the metabolomic fingerprinting approach, the multivariate modeling (hierarchical cluster analysis) and GC-MS. Our preliminary, GC-MS-based metabolomic fingerprinting study underlines the contribution of certain metabolites to the discrimination of patients with lymphohyperplastic diseases. PMID:23806352

Karamani, Anna A; Fiamegos, Yiannis Ch; Vartholomatos, George; Stalikas, Constantine D

2013-08-01

143

Characterization of aroma compounds of Chinese famous liquors by gas chromatography-mass spectrometry and flash GC electronic-nose.  

PubMed

Aroma composition of five Chinese premium famous liquors with different origins and liquor flavor types was characterized by gas chromatography-mass spectrometry (GC-MS) and flash gas chromatographic electronic nose system. Eighty-six aroma compounds were identified, including 5 acids, 34 esters, 10 alcohols, 9 aldehydes, 4 ketones, 4 phenols, and 10 nitrous and sulfuric compounds. To investigate possible correlation between aroma compounds identified by GC-MS and sensory attributes, multivariate ANOVA-PLSR (APLSR) was performed. It turned out that there were 30 volatile composition, ethyl acetate, ethyl propanoate, ethyl 2-methyl butanoate, ethyl 3-methyl butanoate, ethyl lactate, ethyl benzenacetate, 3-methylbutyl acetate, hexyl acetate, 3-methyl-1-butanol, 1-heptanol, phenylethyl alcohol, acetaldehyde, 1,1-diethoxy-3-methyl butane, furfural, benzaldehyde, 5-methyl-2-furanal, 2-octanone, 2-n-butyl furan, dimethyl trisulfied and 2,6-dimethyl pyrazine, ethyl nonanoate, isopentyl hexanoate, octanoic acid, ethyl 5-methyl hexanoate, 2-phenylethyl acetate,ethyl oleate, propyl hexanoate, butanoic acid and phenol, ethyl benzenepropanoate, which showed good coordination with Chinese liquor characteristics. The multivariate structure of this electronic nose responses was then processed by principal component analysis (PCA) and hierarchical cluster analysis (HCA). According to the obtained results, GC-MS and electronic nose can be used for the differentiation of the liquor origins and flavor types. PMID:24333641

Xiao, Zuobing; Yu, Dan; Niu, Yunwei; Chen, Feng; Song, Shiqing; Zhu, Jiancai; Zhu, Guangyong

2014-01-15

144

Sensitive determination of bromate in ozonated and chlorinated water, and sea water by gas chromatography-mass spectrometry after derivatization.  

PubMed

A sensitive gas chromatographic method has been established for the determination of bromate in ozonated and chlorinated water, and in sea water. With acidic conditions, bromate reacts with chloride to form bromine, which reacts with 2,6-dialkylphenol to form 4-bromo-2,6-dialkylphenol. The organic derivative was extracted with ethyl acetate after quenching remaining oxidants with ascorbic acid, and then measured by gas chromatography-mass spectrometry (GC-MS). The lowest detection limit and limit of quantification of bromate in drinking water were 0.02 and 0.07 ?g/L, respectively, and the calibration curve showed good linearity with r=0.998. The 32 common ions did not interfere even when present in 100-fold excess over the bromated ion. The accuracy was in a range of 102-106% and the precision of the assay was less than 6% in chlorinated and ozonated tap water, ozonated mineral water, and sea water. The method was sensitive, reproducible and simple enough to permit reliable analysis of bromate to the ng/L level in water. PMID:22227358

Shin, Ho-Sang

2012-02-01

145

Comparative evaluation of liquid chromatographymass spectrometry versus gas chromatographymass spectrometry for the determination of hexabromocyclododecanes and their degradation products in indoor dust  

Microsoft Academic Search

Domestic and office dust samples (n=37) were analyzed for hexabromocyclododecanes (HBCDs) using gas chromatographyelectron-capture negative ionizationmass spectrometry (GCECNI\\/MS) and liquid chromatographyelectrospray tandem mass spectrometry (LCESI\\/MS\\/MS). To determine the best method to quantify HBCDs using GCECNI\\/MS, BDE 128 was used as internal standard (I.S.) in all samples, while 13C-labeled ?-HBCD was used as I.S. in some samples. Total HBCD concentrations (sum

Mohamed Abou-Elwafa Abdallah; Catalina Ibarra; Hugo Neels; Stuart Harrad; Adrian Covaci

2008-01-01

146

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

PubMed

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

Hilkert; Douthitt; Schlter; Brand

1999-07-01

147

Quantitation of diethylene glycol and its metabolites by gas chromatography mass spectrometry or ion chromatography mass spectrometry in rat and human biological samples.  

PubMed

The misuse of the commonly used chemical diethylene glycol (DEG) has lead to many poisonings worldwide. Methods were developed for analysis of DEG and its potential metabolites; ethylene glycol, glycolic acid, oxalic acid, diglycolic acid and hydroxyethoxy acetic acid in human urine, serum and cerebrospinal fluid samples, collected following a DEG-associated poisoning in the Republic of Panama during 2006. In addition, methods were developed for rat blood, urine, kidney and liver tissue to support toxicokinetic analysis during the conduct of DEG acute toxicity studies in the rat. Sample analysis was conducted using two techniques; ion chromatography with suppressed conductivity and negative ion electrospray ionization with MS detection or with gas chromatography using electron impact ionization or methane negative chemical ionization with MS detection. Stable-isotope-labeled analogs of each analyte were employed as quantitative internal standards in the assays. PMID:24668490

Perala, Adam W; Filary, Mark J; Bartels, Michael J; McMartin, Kenneth E

2014-05-01

148

Thermal degradation of deoxybenzoin polymers studied by pyrolysis-gas chromatography/mass spectrometry  

E-print Network

Available online 29 March 2008 Keywords: Flame-retardant polymers Thermal degradation Pyrolysis comprises four main stages: heating, pyrolytic gas evolution, ignition, and flame-spread. Flame retardants- thermic oxidative reactions and thereby limit combustion. On the other hand, non-halogenated flame

149

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...

150

Sensitive and simple determination of mannitol in human brain tissues by gas chromatographymass spectrometry  

Microsoft Academic Search

A simple, reliable and sensitive gas chromatographicmass spectrometric method was devised to determine the level of mannitol in various human brain tissues obtained at autopsy. Mannitol was extracted with 10% trichloroacetic acid solution which effectively precipitated brain tissues. The supernatant was washed with tert.-butyl methyl ether to remove other organic compounds and to neutralize the aqueous solution. Mannitol was then

Akiko Kiyoshima; Keiko Kudo; Yukiko Hino; Noriaki Ikeda

2001-01-01

151

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

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

152

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

PubMed

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

dos Santos, Thase Fernanda Santana; Aquino, Adriano; Drea, Haroldo Silveira; Navickiene, Sandro

2008-03-01

153

Wastewater analysis for volatile organic sulfides using purge-and-trap with gas chromatography/mass spectrometry.  

PubMed

This paper presented a modified method for the analysis of volatile organic sulfides (VOS) simultaneously with volatile organic compounds (VOC) in wastewater using purge-and-trap with gas chromatography/ mass spectrometry. Calibration standards were prepared using filtered and nitrogen-purged VOS-free wastewater, acidified to pH 1.4. Samples were also acidified to pH 1.4. This approach minimized the oxidation of methanethiol to dimethyl disulfide (DMDS), which hampered the liquid-phase analysis of VOS. Compounds were concentrated from the liquid phase, and automated analyses were performed without additional equipment, other than that required for routine wastewater VOC analysis. The linear range was 5 to 500 microg/L, with r2 > or = 0.99. The average recovery from replicate analyses of spiked samples was 81 +/- 0.5% for methanethiol, 100 +/- 1.5% fordimethyl sulfide (DMS), and 92 +/- 1.5% for DMDS. Method detection limits were 4.8, 2.8, and 1.2 microg/L for methanethiol, DMS, and DMDS, respectively. The relative percent differences were between 0 and 8%. PMID:17489280

Cheng, Xianhao; Peterkin, Earl; Narangajavana, Kanthaka

2007-04-01

154

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

PubMed

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

Oh, Jin-Aa; Shin, Ho-Sang

2014-11-16

155

Application of gas chromatography-mass spectrometry with selected ion monitoring to the urinanalysis of 4-pyridoxic acid.  

PubMed

An analytical protocol has been developed for the analysis of urinary 4-pyridoxic acid (4-PA) by gas chromatography-mass spectrometry (GC-MS) for use in metabolic studies. Aliquots of urine were deproteinised and fractionated by isocratic reversed-phase high-performance liquid chromatography. The eluent fraction containing the 4-PA was collected, freeze-dried and silylated using N-methyl-N-(tert.-butyldimethylsilyl)trifluoroacetamide. Derivatisation produced the mono-tert.-butyldimethylsilyl derivative of 4-PA lactone. This derivative was readily amenable to GC-MS analysis in the electron ionisation (70 eV) mode, yielding a prominent fragment ion at m/z 222 ([M-57]+; base peak). A heavy isotope-labelled derivative of pyridoxine [dideuteriated pyridoxine; 3-hydroxy-4-(hydroxymethyl)-5-[hydroxymethyl-2H2]-2-methylpyridine] has been synthesised and is being employed to determine the kinetics of labelling of the body pools of vitamin B6. Kinetic measurements are based on the determination of the relative proportions of metabolically produced deuterium-labelled and non-labelled 4-PA in urine, obtained from stable isotope ratios determined by low-resolution selected ion monitoring using a bench-top quadrupole GC-MS system. PMID:1452608

Leyland, D M; Evershed, R P; Edwards, R H; Beynon, R J

1992-10-23

156

Simultaneous determination of 76 micropollutants in water samples by headspace solid phase microextraction and gas chromatography-mass spectrometry.  

PubMed

This study focuses on the development of an analytical method based on headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) for the simultaneous determination of 76 micropollutants in water samples. The selected micropollutants include volatile organic compounds (VOCs) (e.g. chlorobenzenes, chloroalkanes), endocrine disrupting compounds (EDCs) (e.g. bisphenol A and tributyl phosphate), odour compounds (e.g. limonene, phenol), fragrance allergens (e.g. geraniol, eugenol) and some pesticides (e.g. heptachlor, terbutryn). The experimental conditions affecting their extraction, such as the type of fibre, temperature and time of extraction, sample volume and ionic strength of the samples were optimized using HS-SPME. The method showed good linear range, reproducibility between days, repeatability and low detection limits (at ng L(-1) levels). The validated method has been applied to determine the target organic micropollutants in aqueous samples from different experimental research units of surface water, sea water, waste water and those effluents of advance membrane treatments. The optimized method showed good performance in the different types of samples studied. The analysis revealed the presence of several micropollutants at concentrations between 20 and 5000 ?g L(-1), such as ethylbenzene, o-xylene, p-isopropilbenzene, D-limonene, citral and isoeugenol, due to the fact that these species are commonly used in domestic and industrial applications. PMID:24148498

Martnez, C; Ramrez, N; Gmez, V; Pocurull, E; Borrull, F

2013-11-15

157

Quantification of trimethylsilyl derivatives of amino acid disease biomarkers in neonatal blood samples by gas chromatography-mass spectrometry.  

PubMed

A novel analytical procedure was developed for the rapid determination of disease biomarkers of maple syrup urine disease (MSUD), L-valine, L-leucine, L-isoleucine, and L-phenylalanine in dried blood spots. Amino acids extracted from neonatal dried blood spots were rapidly derivatized with bis-(trimethylsilyl)trifluoroacetamide (BSTFA) and then analyzed by gas chromatography-mass spectrometry (GC-MS). Derivatization conditions and the method validation were studied: optimal derivatization conditions were acetonitrile as reaction solvent, a temperature of 100 degrees C, and a reaction time of 30 min. The proposed method provided a detection limit lower than 2.0 microM, recovery between 92% and 106%, and relative standard deviation less than 8.0%. The method was further tested in screening for neonatal MSUD by determination of L-valine, L-leucine, L-isoleucine, and L-phenylalanine in blood samples. The experimental results show that GC-MS following BSTFA derivatization is a rapid, simple, and sensitive method for the determination of amino acid disease biomarkers in blood samples, and is a potential tool for fast screening of MSUD. PMID:16385411

Shen, Xizhong; Deng, Chunhui; Wang, Ben; Dong, Ling

2006-02-01

158

Study of the chemical derivatization of zearalenone and its metabolites for gas chromatography-mass spectrometry analysis of environmental samples.  

PubMed

This study compares different silylation procedures of zearalenone and its metabolites: alpha-zearalenol, beta-zearalenol, zearalanone, alpha-zearalanol and beta-zearalanol for gas chromatography-mass spectrometry (GC-MS) analysis. Four silylating agents among the most frequently used to derivatize polar organic compounds were tested: N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA), N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA), N,N-diethyltrimethylsilylamine (TMSDEA) and a commercial mixture of N,O-bis(trimethylsilyl)acetamide, trimethylchlorosilane and N-trimethylsilyimidazole. Previous studies showed that the addition of polar and/or basic solvents can significantly improve the yield of a reaction of derivatization. In this work, four solvents were tested: pyridine, dimethylformamide, acetonitrile and acetone. The influence of each solvent was studied as a function of the silylating agent/solvent ratio. The influences of the temperature and of the reaction time on the reaction yields were also evaluated. A GC-MS quantitation method associating methanol chemical ionization and selected ion storage with three ions was developed and successfully tested on a reconstituted sediment spiked in zearalenone and its metabolites. PMID:18394636

Kinani, Said; Bouchonnet, Stphane; Bourcier, Sophie; Porcher, Jean-Marc; At-Assa, Slim

2008-05-01

159

[Determination of environmental estrogens in pharmacy wastewater using solid-phase extraction-gas chromatography/mass spectrometry with derivatization].  

PubMed

A method for the determination of estrone (E1), estradiol (E2), ethinylestradiol (EE2) and estriol (E3) in pharmacy wastewater was developed using solid-phase extraction-gas chromatography/mass spectrometry (SPE-GC/MS) with derivatization. The sample was extracted by an SPE column, derivatized by bis (trimethylsilyl) trifluoroacetamide (BSTFA), and analyzed by GC/MS. The detection limits were 1.8-4.7 ng/L, and the relative standard deviations were 2.3%-9.1% (n = 8). The recoveries of above four environmental estrogen compounds were (94.0 +/- 2.9)% to (101 +/- 3.8)%. The method can be applied in the determination of the estrogenic compounds in wastewater samples successfully. The concentrations of EE2 and E1 in wastewater were 396.6 ng/L and 39.9 ng/L, respectively, and the removal rates of EE2 and E1 were 35%-40% after traditional biological treatment. The results demonstrated that the removal efficiency was not satisfactory and the traditional treatment process of wastewater containing estrogen compounds from pharmaceuticals factory should be improved. PMID:19160764

Huang, Cheng; Jiang, Liying; Chen, Jianmeng; Chen, Xiao

2008-09-01

160

Use of gas chromatography/mass spectrometry with positive chemical ionization for the determination of opiates in human oral fluid.  

PubMed

An analytical method for the simultaneous determination of codeine, morphine and 6-acetylmorphine (6AM) in human oral fluid was developed. The method involves liquid-liquid extraction in Toxitubes A, derivatization with 99:1 (v/v) N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA)/trimethylchlorosilane (TMCS), and gas chromatography/mass spectrometry with positive chemical ionization (GC/PCI-MS) determination. The detector response was linear over the concentration range 30-500 ng/mL with coefficients of correlation higher than 0.99. The precision was acceptable with coefficients of variation less than 7.5%. The limits of detection achieved were 0.7 ng/mL for codeine, 2.0 ng/mL for morphine, and 0.6 ng/mL for 6AM. The method proposed was applied to 80 oral fluid samples from opiates users, 98% of which were positive for the three analytes. Human oral fluid is a suitable biological fluid for the determination of opiates by GC/PCI-MS. PMID:16548052

Cmpora, Pamela; Bermejo, Ana Mara; Tabernero, Mara Jess; Fernndez, Purificacin

2006-01-01

161

Coupled two-step microextraction devices with derivatizations to identify hydroxycarbonyls in rain samples by gas chromatography-mass spectrometry.  

PubMed

Coupling a two-step liquid-phase microextraction (LPME) with O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine/bis(trimethylsilyl)trifluoroacetamide (PFBHA)/(BSTFA) derivatization was developed to detect hydroxycarbonyls in rainwater samples using gas chromatography-mass spectrometry (GC-MS). LPME provides a fast and inexpensive pre-concentration, and miniaturized extraction to analyze the target compounds rainwater samples. Derivatization techniques offer a clear method to identify target compounds. The hydroxycarbonyls were determined using two-step derivatizations. Dynamic-LPME was applied in the first derivatization, and head-space single drop derivatization was employed in the second reaction. The LODs varied from 0.023 to 4.75 microg/l. The calibration curves were linear for at least two orders of magnitude with R2>or=0.994. The precision was within 6.5-12%, and the relative recoveries in rainwater were more than 89% (the amount added ranged from 0.3 to 15 microg/l). A field sample was found to contain 2.54 microg/l of hydroxyacetone and 0.110 microg/l of 3-hydroxy-2-butanone. Hydroxyacetone was also detected in one of the tested samples at a concentration of 2.39 microg/l. PMID:16643930

Chen, Pai-Shan; Huang, Shang-Da

2006-06-23

162

Measurement of urinary F(2)-isoprostanes by gas chromatography-mass spectrometry is confounded by interfering substances.  

PubMed

Analysis of F(2)-isoprostanes in urine using gas chromatography-mass spectrometry is confounded by the presence of endogenous compounds interfering with the internal standard, 15-F(2t)-IsoP-d(4) (m/z 573). Previous efforts to resolve the 15-F(2t)-IsoP-d(4) from co-eluting peaks with different solid phase extractions were unsuccessful. This study has now used a highly-deuterated, d(9)-analogue of the derivatization agent N,O-Bis(trimethyl-d(9)-silyl) trifluoroacetamide (BSTFA-d(9)) yielding trimethylsilyl ethers, but this was not successful in resolving the 15-F(2t)-IsoP-d(4) from co-eluting peaks. It was hypothesized that interfering peaks at m/z 573 could be the tetrahydro analogue of 15-F(2t)-IsoP. However, using an authentic standard showed the interfering peaks are not due to this metabolite. In subsequent experiments good resolution was shown of the 15-F(2t)-IsoP peak using 8-F(2t)-IsoP-d(4) (m/z 573) as the internal standard. These data show that care must be taken when using GC-MS for quantitation of F(2)-IsoPs to prevent interfering substances affecting the results. PMID:19929242

Mas, Emilie; Barden, Anne; Durand, Thierry; Galano, Jean-Marie; Croft, Kevin D; Mori, Trevor A

2010-02-01

163

A serum metabolomic investigation on lipoprotein lipase-deficient mice with hyperlipidemic pancreatitis using gas chromatography/mass spectrometry  

PubMed Central

Hypertriglyceridemia (HTG) is often associated with acute pancreatitis. The relationship between these diseases and the role that hypertriglyceridemia plays in acute pancreatitis pathogenesis remains to be elucidated. In the present study, in order to investigate the mechanisms of hyper-lipidemic acute pancreatitis (HLP), we established an animal model using lipoprotein lipase (LPL)-deficient heterozygous mice injected with caerulein. Susceptibility to pancreatitis in LPL-deficient heterozygous mice was compared with that of wild-type mice after intraperitoneal (i.p.) injections of caerulein by determining amylase release and pancreatic pathological scores. Furthermore, serum metabolome was detected through chemical derivatization followed by gas chromatography/mass spectrometry (GC/MS). GC/MS data were analyzed by orthogonal-projection to latent structures-discriminant analysis (OPLS-DA). Caerulein induced increased levels of serum amylase and more severe pancreatic inflammation in LPL-deficient mice compared to wild-type mice. HLP was discriminated more accurately from healthy controls by the metabolites, including valine, leucine and citrate. The metabolites included valine, leucine, citrate, malic acid, proline, tetradecanoic acid (14:0), glutamine and oleic acid (18:1). Changes in energy, fat and amino acid metabolism were also evident. In conclusion, LPL-deficient heterozygous mice with hypertriglyceridemia (HTG) exhibited enhanced susceptibility to acute pancreatitis. GC/MS data revealed differences between healthy and HLP mice. Therefore, this technique is novel and a useful tool for the study of the HLP pathogenetic mechanism. PMID:24648970

TANG, MAOCHUN; HU, GOUYONG; ZHAO, YAN; SU, MINGMING; WANG, YUHUI; JIA, WEI; QIU, YUNPING; LIU, GEORGE; WANG, XINGPENG

2013-01-01

164

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

PubMed

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

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

2014-01-01

165

Solid-phase analytical derivatization of alkylphenols in fish bile for gas chromatography-mass spectrometry analysis.  

PubMed

Solid-phase analytical derivatization (SPAD) with bis(trimethylsilyl)trifluoroacetamide (BSTFA) has successfully been used as a sample preparation method for determination of (APs) in fish bile treated with beta-glucuronidase and sulfatase. Derivatized APs were analysed by gas chromatography-mass spectrometry in the electron ionization mode (GC-EI-MS). Overall limits of detection (LODs) ranged from 5 to 18ng/g bile for 19 out of 21 investigated compounds. LODs were not determined for 4-methylphenol and 4-tert-octylphenol due to high background levels in control bile. Recoveries ranged from 83 to 109%. The analysed APs vary in degree of alkylation from methyl (C(1)) to nonyl (C(9)), and represent various pollution sources, including produced water (PW) discharge from the offshore oil industry. The applicability and sensitivity of the method has been demonstrated by analysis of bile taken from Atlantic cod (Gadus morhua L.) exposed to two dilutions of PW (1:500 and 1:1500) in a continuous flow system. PMID:18243219

Jonsson, Grete; Cavcic, Admira; Stokke, Tone U; Beyer, Jonny; Sundt, Rolf C; Brede, Cato

2008-03-01

166

Determination of fecal sterols by gas chromatography-mass spectrometry with solid-phase extraction and injection-port derivatization.  

PubMed

Injection-port derivatization combined with solid-phase extraction (SPE) was developed and applied for the first time to determine five types of fecal sterols (coprostanol, cholestanol, epicholestanol, epicoprostanol and cholesterol) with gas chromatography-mass spectrometry (GC-MS). In this method, silylation of fecal sterols was performed with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) at GC injection-port. The factors influential to this technique such as injection-port temperature, purge-off time, derivatization reagent (BSTFA) volume, and the type of organic solvent were investigated. In addition, the conditions of SPE (including the type of SPE cartridge, the type of elution organic solvent) were also studied. After SPE followed by injection-port silylation by GC-MS, good linearity of analytes was achieved in the range of 0.02-10ng/mL with coefficients of determination, R(2)>0.995. Good reproducibility was obtained with relative standard deviation less than 19.6%. The limits of detection ranged from 1.3ng/mL to 15ng/mL (S/N=3) in environmental water samples. Compared with traditional off-line silylation of fecal sterols performed with water bath (60 degrees C, 30min), this injection-port silylation method is much simpler and convenient. The developed method has been successfully applied for the analysis of fecal sterols from real environmental water samples. PMID:19147150

Wu, Jingming; Hu, Ruikang; Yue, Junqi; Yang, Zhaoguang; Zhang, Lifeng

2009-02-13

167

Development of a Gas Chromatography-Mass Spectrometry Method for the Quantification of Glucaric Acid Derivatives in Beverage Substrates  

PubMed Central

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

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

2014-01-01

168

Determination of phosmet and its metabolites in olives by matrix solid-phase dispersion and gas chromatography-mass spectrometry.  

PubMed

An accurate method based on matrix solid-phase dispersion (MSPD), and gas chromatography-mass spectrometry (GC/MS) was developed for determination of phosmet residues and its metabolites (phosmet-oxon, phthalimide, N-hydroxymethylphthalimide, and phthalic acid) in olive fruits. After testing different sorbents and eluents for MSPD extraction, C(18) and acetonitrile were found to be the most appropriate for clean-up of the samples, in terms of yields and efficient removal of interfering compounds. All analytes were determined in selective ion monitoring (SIM) mode following a derivatization step with N,O-bis-trimethylsilyltrifluoroacetamide (BSTFA) containing 1% of trimethylchlorosilane (TMCS), except for phosmet and phosmet-oxon which were analyzed directly. The method showed suitable linearity (correlation coefficients higher than 0.8919 for all the compounds) and suitable sensitivity (limit of detection lower than 0.06mg/kg). It was successfully applied in the analysis of olive fruits collected during the preharvest interval and olive oil. Phosmet residues found in all samples were lower than the maximum residue limits established by legislation (2mg/kg). PMID:19073064

Cunha, Sara C; Fernandes, Jos O; Beatriz, M; Oliveira, P P

2007-09-30

169

Validation of Biomarkers for Distinguishing Mycobacterium tuberculosis from Non-Tuberculous Mycobacteria Using Gas Chromatography?Mass Spectrometry and Chemometrics  

PubMed Central

Tuberculosis (TB) remains a major international health problem. Rapid differentiation of Mycobacterium tuberculosis complex (MTB) from non-tuberculous mycobacteria (NTM) is critical for decisions regarding patient management and choice of therapeutic regimen. Recently we developed a 20-compound model to distinguish between MTB and NTM. It is based on thermally assisted hydrolysis and methylation gas chromatography-mass spectrometry and partial least square discriminant analysis. Here we report the validation of this model with two independent sample sets, one consisting of 39 MTB and 17 NTM isolates from the Netherlands, the other comprising 103 isolates (91 MTB and 12 NTM) from Stellenbosch, Cape Town, South Africa. All the MTB strains in the 56 Dutch samples were correctly identified and the model had a sensitivity of 100% and a specificity of 94%. For the South African samples the model had a sensitivity of 88% and specificity of 100%. Based on our model, we have developed a new decision-tree that allows the differentiation of MTB from NTM with 100% accuracy. Encouraged by these findings we will proceed with the development of a simple, rapid, affordable, high-throughput test to identify MTB directly in sputum. PMID:24146846

Dang, Ngoc A.; Kuijper, Sjoukje; Walters, Elisabetta; Claassens, Mareli; van Soolingen, Dick; Vivo-Truyols, Gabriel; Janssen, Hans-Gerd; Kolk, Arend H. J.

2013-01-01

170

Analysis of benzothiazole in Italian wines using headspace solid-phase microextraction and gas chromatography-mass spectrometry.  

PubMed

Benzothiazoles are a part of the molecular structure of a large number of natural products, biocides, drugs, food flavors, and industrial chemicals. They also appear in the environment mainly as a result of their production and use as rubber vulcanization accelerators. A new headspace solid-phase microextraction (HS-SPME) method for analysis of benzothiazole (BTH) in wine is described. This method is fast, inexpensive, and does not require solvents. The detection limit of BTH in wine was 45 ppt with linearity up to 100 ppb. The quantification of BTH is performed by the standard additions method and does not require the use of an internal standard. We have analyzed 12 wines from different grape varieties grown in several regions, using SPME extraction and gas chromatography-mass spectrometry (GC-MS) detection. Under these experimental conditions, benzothiazole was found in all wines analyzed. Concentration levels in samples varied from 0.24 microg/L (Vermentino) to 1.09 microg/L (Franciacorta). PMID:10775378

Bellavia, V; Natangelo, M; Fanelli, R; Rotilio, D

2000-04-01

171

Quantitative solid phase microextraction--gas chromatography mass spectrometry analysis of five megastigmatrienone isomers in aged wine.  

PubMed

Megastigmatrienone is a key flavor compound in tobacco. It has also been detected in wine, where it may contribute to a tobacco/incense aroma, but its importance and concentration in wines had never previously been evaluated. A method was developed and validated for quantifying the five megastigmatrienone isomers in red and white wines. Megastigmatrienone isomers were extracted by headspace solid-phase microextraction (HS-SPME), with a 65 ?m film thickness polydimethylsiloxane-divinylbenzene (PDMS-DVB) fiber and analyzed using gas chromatography-mass spectrometry (GC/MS) in selected ion monitoring mode (SIM). Several parameters affecting the length of the adsorption process (i.e., adding salt, extraction time and extraction temperature) were tested. The optimum analytical conditions were established. The LOQ were between 0.06 ?g L(-1) and 0.49 ?g L(-1) for white wine and 0.11 ?g L(-1) and 0.98 ?g L(-1) for red wine, repeatability in both types of wine was less than 10% and recovery ranged from 96% for white wine to 94% for red wine. The five isomers of megastigmatrienone were quantified in red and white wines for the first time. Concentrations ranged from 2 ?g L(-1) to 41 ?g L(-1) in both red and white wines. Initial results revealed a link between wine aging and megastigmatrienone levels, indicating that megastigmatrienone may be a component in wine "bouquet". PMID:24528661

Slaghenaufi, Davide; Perello, Marie-Claire; Marchand-Marion, Stphanie; Tempere, Sophie; de Revel, Gilles

2014-02-27

172

An isotope dilution headspace method with gas chromatography-mass spectrometry for determination of propylene oxide in food.  

PubMed

A method based on isotope dilution headspace and gas chromatography-mass spectrometry was developed for the determination of propylene oxide in foods. Optimum method sensitivity was achieved by the addition of NaCl in water at saturation and with the sample solution incubated at 90 degrees C. The method had good repeatability with relative standard deviations of 6.0, 7.6 and 2.2% at 5, 20 and 40 microg l(-1), respectively. The method was used to determine propylene oxide in 36 selected food composite samples from the 2007 Canadian total diet study. Propylene oxide was not detected in any samples analyzed with an average method detection limit of 0.5 ng g(-1). Hydrolysis of propylene oxide in water was observed as a first-order reaction with a half-life of 15 h at room temperature and less than 10 min at 90 degrees C. This confirms that it is very unlikely to find propylene oxide in foods as consumed due to its volatility and reaction with water. PMID:19680922

Cao, Xu-Liang; Corriveau, Jeannette

2009-04-01

173

Quantitative determination of CGS 18102A, a new anxiolytic, in human plasma using capillary gas chromatography/mass spectrometry.  

PubMed

CGS 18102A is a novel hexahydrobenzopyranopyridine that has a mixed pharmacological profile of 5-HT-1A agonist and 5-HT-2 antagonist properties. Based upon these mechanisms, the compound is predicted to have anxiolytic efficacy with possible efficacy in depression. Preclinical studies in the rat have shown the drug to be well absorbed and extensively metabolized. Because of the anticipated low plasma levels in humans a gas chromatography/mass spectrometry (GC/MS) analytical method has been developed and validated to determine plasma concentrations of CGS 18102A in early clinical studies. The method utilizes CGS 18416A as the internal standard. Samples (1 mL) were extracted with pentane:ethyl acetate (75:25, v:v). Extracts were then concentrated and analysed directly by GC/MS. Separation was accomplished on a methylsilicone capillary column (30 m x 0.32 mm i.d.). GC/MS was carried out under positive ion ammonia CI conditions, with selected ion monitoring of the [M + H]+ ions (m/z = 262 and 248) for CGS 18102A and CGS 18416A, respectively. The method was successively applied to the analysis of clinical samples from an ascending multidose safety and tolerability study conducted in six normal healthy male volunteers. PMID:1361157

Leal, M; Hayes, M J; Powell, M L

1992-01-01

174

A serum metabolomic investigation on hepatocellular carcinoma patients by chemical derivatization followed by gas chromatography/mass spectrometry.  

PubMed

The purpose of this study was to investigate the serum metabolic difference between hepatocellular carcinoma (HCC, n = 20) male patients and normal male subjects (n = 20). Serum metabolome was detected through chemical derivatization followed by gas chromatography/mass spectrometry (GC/MS). The acquired GC/MS data was analyzed by stepwise discriminant analysis (SDA) and support vector machine (SVM). The metabolites including butanoic acid, ethanimidic acid, glycerol, L-isoleucine, L-valine, aminomalonic acid, D-erythrose, hexadecanoic acid, octadecanoic acid, and 9,12-octadecadienoic acid in combination with each other gave the strongest segregation between the two groups. By applying these variables, our method provided a diagnostic model that could well discriminate between HCC patients and normal subjects. More importantly, the error count estimate for each group was 0%. The total classifying accuracy of the discriminant function tested by SVM 20-fold cross validation was 75%. This technique is different from traditional ones and appears to be a useful tool in the area of HCC diagnosis. PMID:18767022

Xue, Ruyi; Lin, Zhenxin; Deng, Chunhui; Dong, Ling; Liu, Taotao; Wang, Jiyao; Shen, Xizhong

2008-10-01

175

Unknown exposures: gaps in basic characterization addressed with person-portable gas chromatography-mass spectrometry instrumentation.  

PubMed

A newly developed person-portable gas chromatography-mass spectrometry (GC-MS) system was used to analyze several solvent standards, contact cement, paint thinner, and polychlorinated biphenyl samples. Passive solid phase microextraction sampling and fast chromatography with a resistively heated low thermal mass GC column were used. Results (combined sampling and analysis) were obtained in <2 min for solvent, contact cement, and paint thinner samples, and in <13 min for the polychlorinated biphenyl sample. Mass spectra produced by the small toroidal ion trap detector used were similar to those produced with heavily used transmission quadrupole mass spectrometers for polychlorinated biphenyl compounds, simple alkanes, and cycloalknes, while mass spectra for benzene and the ketone compounds analyzed showed evidence for ion/molecule reactions in the ion trap. For one of the contact cement samples analyzed, no evidence was found to indicate the presence of n-hexane, although the relevant material safety data sheet listed this ingredient. Specific chemical constituents corresponding to a potentially wide range of petroleum distillate compounds were identifiable from GC-MS analyses. The possibility for an improved basic characterization step in the exposure assessment process exists with the availability of fast, person-portable GC-MS, although work is needed to further refine this tool and understand the best ways it may be used. PMID:21318921

Smith, Philip A; Roe, Marc T A; Sadowski, Charles; Lee, Edgar D

2011-03-01

176

Simultaneous determination of tramadol, O-desmethyltramadol and N-desmethyltramadol in human urine by gas chromatography-mass spectrometry.  

PubMed

Analytical procedures for the determination of tramadol (T), O-desmethyltramadol (ODT), and N-desmethyltramadol (NDT) in human urine have been developed and validated using gas chromatography-mass spectrometry (GC/MS). Sample preparation involved liquid-liquid extraction with methyl-tert-butyl ether (MTBE) and followed by back extraction with 0.1 M hydrochloric acid. Proadifen (SKF525A) was selected as internal standard (IS). Extraction efficiencies of T, ODT and NDT were 102.12, 101.30, and 98.21%, respectively. The calibration curves were linear (r(2)>0.99) in the concentration range 10-1000 ng/mL for all compounds. Limits of quantification (LOQ) were 10, 10 and 20 ng/mL for T, ODT and NDT, respectively. Intra-assay precision was within 1.29-6.48% and inter-assay precision was within 1.28-6.84% for T, ODT and NDT. Intra-assay accuracy was within 91.79-106.89% for all analytes. This method detected urine concentrations of T, ODT and NDT in six healthy volunteers for 7 days after administration of 50 mg oral doses of tramadol. PMID:23542669

El-Sayed, Abdel-Aziz Y; Mohamed, Khaled M; Nasser, Ahmed Y; Button, Jennifer; Holt, David W

2013-05-01

177

Gas Chromatography- Mass Spectrometry Based Metabolomic Approach for Optimization and Toxicity Evaluation of Earthworm Sub-Lethal Responses to Carbofuran  

PubMed Central

Despite recent advances in understanding mechanism of toxicity, the development of biomarkers (biochemicals that vary significantly with exposure to chemicals) for pesticides and environmental contaminants exposure is still a challenging task. Carbofuran is one of the most commonly used pesticides in agriculture and said to be most toxic carbamate pesticide. It is necessary to identify the biochemicals that can vary significantly after carbofuran exposure on earthworms which will help to assess the soil ecotoxicity. Initially, we have optimized the extraction conditions which are suitable for high-throughput gas chromatography mass spectrometry (GC-MS) based metabolomics for the tissue of earthworm, Metaphire posthuma. Upon evaluation of five different extraction solvent systems, 80% methanol was found to have good extraction efficiency based on the yields of metabolites, multivariate analysis, total number of peaks and reproducibility of metabolites. Later the toxicity evaluation was performed to characterize the tissue specific metabolomic perturbation of earthworm, Metaphire posthuma after exposure to carbofuran at three different concentration levels (0.15, 0.3 and 0.6 mg/kg of soil). Seventeen metabolites, contributing to the best classification performance of highest dose dependent carbofuran exposed earthworms from healthy controls were identified. This study suggests that GC-MS based metabolomic approach was precise and sensitive to measure the earthworm responses to carbofuran exposure in soil, and can be used as a promising tool for environmental eco-toxicological studies. PMID:24324663

Saxena, Prem Narain

2013-01-01

178

[Simultaneous determination of neutral sugars and uronic acid constituents in a novel bacterial polysaccharide using gas chromatography-mass spectrometry].  

PubMed

The purified novel bacterial polysaccharide was acid-hydrolyzed, followed by the subsequent derivatization using ethanethiol-trifluoroacetic acid and acetic anhydride-pyridine systems sequentially. Our findings differ from the previous reports in that the glucuronic acid was obtained through effective derivatization. The neutral sugars and glucuronic acid were analyzed using gas chromatography-mass spectrometry (GC-MS) with xyloses as an internal standard. The polysaccharide was found to be composed of fucose, glucose, glucuronic acid and galactose, with the relative molar ratio of 1.50: 1.0: 0.79: 2.06. The neutral sugars ratio was similar to the relative molar ratio for fucose, glucose and galactose of 1.76: 1.0: 1.98 through alditol acetates determined by GC. The percentages of glucuronic acid analyzed using either the carbazole and sulfuric acid method or the above method were 16.19% and 14.85%, respectively. These results indicate that it is practicable to use the derivatization method and GC-MS to quantitatively analyze neutral sugars and glucuronic acid simultaneously in polysaccharide. For GC-MS analysis, the procedure was developed for the simultaneous determination of the derivatives in 25 min, and was performed using an HP-5MS column. Molecular ion peaks were observed in the electron ionization (EI) mass spectra. The fragmentation mechanism for glucuronic acid derivative is discussed in detail. PMID:23667990

Wang, Fengqin; Yang, Hangxian; Wang, Yizhen

2013-01-01

179

Retrospective identification of chemical warfare agents by high-temperature automatic thermal desorption-gas chromatography-mass spectrometry.  

PubMed

An automated thermal desorption (ATD)-gas chromatography-mass spectrometry method was developed for the analysis of selected chemical warfare (CW) agents. Suitable methods were developed for analytes of high volatility to low volatility. The less volatile CW agents required the purchase and installation of a high-temperature valve upgrade kit allowing valve temperatures of up to 260 degrees C to be reached. The limit of detection was 50 ng on the tube for most CW agents in full scan. Chloropicrin exhibited some temperature dependence, with detection limits improving as ATD temperatures were decreased below 150 degrees C. A sample storage trial was undertaken to establish the most suitable storage environment for CW agents adsorbed onto Tenax TA. Temperature and time of storage were found to influence recovery of analytes with best recoveries being observed after 1 day storage in a freezer (-12 degrees C). This method was evaluated during a trial of procedures for sampling and identification of chemical agents at Porton Down, UK. Sulfur mustard was detected downwind of a simulated exploded munition. PMID:11519809

Carrick, W A; Cooper, D B; Muir, B

2001-08-01

180

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

PubMed

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

Tang, Bing; Isacsson, Ulf

2006-12-22

181

Linear and cyclic methylsiloxanes in air by concurrent solvent recondensation-large volume injection-gas chromatography-mass spectrometry.  

PubMed

In the present work, a simple and fast method for the analysis of linear and cyclic methylsiloxanes in ambient air based on active sampling combined with gas chromatography - mass spectrometry (GC-MS) was developed. The retention efficiency of five sampling sorbents (activated coconut charcoal, Carbopack B, Cromosorb 102, Cromosorb 106 and Isolute ENV+) was evaluated and Isolute ENV+ was found to be the most effective. A volume of 2700 L of air can be sampled without significant losses of the most volatile methylsiloxanes. To improve the sensitivity of the GC-MS method, concurrent solvent recondensation - large volume injection (CSR-LVI), using volumes up to 30 l of sample extract, is proposed and limits of quantification down to 0.03-0.45 ng m(-3), good linearity (r>0.999) and precision (RSD %<9%) were obtained. The developed method was applied to the analysis of ambient air. Concentrations of linear and cyclic methylsiloxanes in indoor air ranging from 3.9 to 319 ng m(-3) and between 48 and 292668 ng m(-3), were obtained, respectively, while levels from 6 to 22 ng m(-3) for linear and between 2.2 and 439 ng m(-3) for cyclic methylsiloxanes in outdoor air from Barcelona (Spain), were found. PMID:24274295

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

2014-01-01

182

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

PubMed

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 2h), 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 1h-irradiated group was more similar to the control group (0h) than the 2h-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

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

2012-08-01

183

Metabolite profiling of sucrose effect on the metabolism of Melissa officinalis by gas chromatography-mass spectrometry.  

PubMed

The effect of sugar on plant metabolism, which is known to be similar to hormone-like signaling, was metabolomically studied using Melissa officinalis (lemon balm). The metabolite profiles of M. officinalis treated with sucrose were analyzed by gas chromatography-mass spectrometry (GC-MS) and principal component analysis (PCA). A total of 64 metabolites from various chemical classes including alcohols, amines, amino acids, fatty acids, inorganic acids, organic acids, phosphates, and sugars were identified by GC-MS. Three groups treated with different sucrose concentrations were clearly separated by PCA of their metabolite profiles, indicating changes in the levels of many metabolites depending on the sucrose concentration. Metabolite profiling revealed that treatment with a higher sucrose level caused an increase in the levels of metabolites such as sugars, sugar alcohols, and sugar phosphates, which are related to the glycolytic pathway of M. officinalis. Furthermore, proline and succinic acid, which are associated with the proline-linked pentose phosphate pathway, the shikimic acid pathway, and the biosynthesis of phenylpropanoids, also increased with increasing sucrose concentration. Therefore, these metabolic changes induced by sucrose ultimately led to the increased production of flavonoids such as caffeic acid via the biosynthetic pathway of phenylpropanoids. This study demonstrated that the abundance changes in some primary and secondary metabolites were somewhat interlocked with each other in response to sucrose. PMID:21301821

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

2011-04-01

184

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

PubMed

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

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

2013-01-15

185

Speciation of butyltin compounds in marine sediments by preconcentration on C60 and gas chromatography-mass spectrometry.  

PubMed

A new method for the speciation of butyltin compounds by solid phase extraction and direct injection using gas chromatography-mass spectrometry (GC/MS) is described. The compounds were complexed with sodium diethyldithiocarbamate and retained on a C60 sorbent column. The neutral chelates of butyltin compounds were eluted with ethyl acetate containing NaBPr4 as derivatising reagent. The main analytical figures of merit of the proposed method for 10 ml of sample are: linear range 0.2-35 ng/g expressed as Sn; limits of detection, 0.07, 0.09 and 0.10 ng/g as Sn for monobutyltin, dibutyltin and tributyltin, respectively. No interferences from metal ions such as Zn2+, Fe3+, Sb3t, Pb2+, Ni2+ and Mn2+ were observed in the determination of organotin compounds. The validation of method was performed out by the analysis of a standard reference sediment (CRM 462). The method was also applied to the determination of butyltin compounds in marine sediment samples. PMID:14753683

Muoz, J; Baena, J R; Gallego, M; Valcrcel, M

2004-01-16

186

Comparison of gas chromatography/mass spectrometry and immunoassay techniques on concentrations of atrazine in storm runoff.  

PubMed

Gas chromatography/mass spectrometry (GC/MS) and enzyme-linked immunosorbent assay (ELISA) techniques were used to measure concentrations of dissolved atrazine in 149 surface-water samples. Samples were collected during May 1992-September 1993 near the mouth of the White River (Indiana) and in two small tributaries of the river. GC/MS was performed on a Hewlett-Packard 5971A with electron impact ionization and selected ion monitoring of filtered water samples extracted by C-18 solid phase extraction; ELISA was performed with a magnetic-particle-based assay with photometric analysis. ELISA results compared reasonably well to GC/MS measurements at concentrations below the Maximum Contaminant Level for drinking water set by the U.S. Environmental Protection Agency (3.0 microg/L), but a systematic negative bias was observed at higher concentrations. When higher concentration samples were diluted into the linear range of calibration, the relation improved. A slight positive bias was seen in all of the ELISA data compared to the GC/MS results, and the bias could be partially explained by correcting the ELISA data for cross reactivity with other triazine herbicides. The highest concentrations of atrazine were found during the first major runoff event after the atrazine was applied. Concentrations decreased throughout the rest of the sampling period even though large runoff events occurred during this time, indicating that most atrazine loading to surface waters in the study area occurs within a few weeks after application. PMID:8854831

Lydy, M J; Carter, D S; Crawford, C G

1996-10-01

187

Filtration efficiency validation of glass wool during thermal desorption-gas chromatography-mass spectrometer analysis of fine atmospheric particles.  

PubMed

Thermal desorption-gas chromatography-mass spectrometer (TD-GC-MS) technique has been widely used for analysis of semi-violate organic compounds on atmospheric aerosol. To prevent GC column from being damaged by fine solid particles during thermal desorption process, glass wool as filter mat is indispensible. However, the filtration efficiency has never been validated. In this paper, the most penetrating particle size and the minimum packing thickness of glass wool were calculated based on classical filtration theory. According to the calculation results, packing parameters of glass wool were optimized experimentally using silica particles. It is demonstrated that glass wool with a packing thickness of 30mm, solidity of 0.039 can effectively block these fine solid particles from penetrating at normal thermal desorption conditions (T=300C, u=0.4-4cm/s). Finally, the filtration efficiency of glass wool was further confirmed with real PM2.5 samples. Under the validated filtration condition, TD-GC-MS was applied for the analysis of non-polar organic compounds on real PM2.5 samples, and very good results were obtained. PMID:25578046

Hao, Liang; Wu, Dapeng; Ding, Kun; Meng, Hu; Yan, Xiaohui; Guan, Yafeng

2015-02-01

188

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

PubMed

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

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

2007-11-15

189

Characterization of important odorants in steamed male Chinese mitten crab (Eriocheir sinensis) using gas chromatography-mass spectrometry-olfactometry.  

PubMed

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

Wu, Na; Gu, Saiqi; Tao, Ningping; Wang, Xichang; Ji, Siru

2014-07-01

190

Determination of herbicides, including thermally labile phenylureas, by solid-phase microextraction and gas chromatography-mass spectrometry.  

PubMed

A method for the determination of 10 herbicides, including thermally unstable compounds, has been developed. The method uses solid-phase microextraction (SPME) with a polyacrylate fibre. Separation, identification and quantification were accomplished with gas chromatography-mass spectrometry. The herbicides chosen belong to different chemical groups and were alachlor, atrazine, chlorotoluron, diclofop, diflufenicam, ethofumesate, isoproturon, linuron, terbutryn and trifluralin. In the present work we studied the chromatographic behaviour of three phenylureas as a function of the medium and injection mode employed. The compounds generated as a function of the solvent used in direct injection of the phenylureas (ethyl acetate, methanol and methanol-water) and those obtained when injection was accomplished using the polyacrylate fibre were determined. The results allow us to propose a method for the determination of stable and thermally unstable herbicides as long as a preconcentration step involving SPME is carried out. In the proposed method, the limits of detection varied between 0.02 microg/l for ethofumesate and 0.11 microg/l for chlorotoluron. The method was applied to the determination of these herbicides in surface and ground water samples, performing quantification by standard addition calibration. The contents of chlorotoluron and atrazine found were significantly equal to those obtained using HPLC after a preconcentration stepwith styrene-divinylbenzene sorbents. PMID:12885074

Carabias-Martnez, R; Garca-Hermida, C; Rodrguez-Gonzalo, E; Soriano-Bravo, F E; Hernndez-Mndez, J

2003-06-20

191

[Determination of 23 phthalate esters in food by solid-phase extraction coupled with gas chromatography-mass spectrometry].  

PubMed

A method for the simultaneous determination of 23 phthalate esters in food samples by solid-phase extraction coupled with gas chromatography-mass spectrometry (SPE-GC-MS) was developed and evaluated. The samples were extracted with hexane or acetonitrile, and cleaned up with a glass ProElut PSA SPE column. The identification and quantification were performed by GC-MS in selected ion monitoring (SIM) mode. The extraction processes of different foods were investigated. The calibration curves of phthalate esters showed good linearity in the range of 0.05-5 mg/L (0.5-5 mg/L for diisononyl phthalate (DINP), diisodecyl-phthalate (DIDP)) with the correlation coefficients (r) between 0.984 8 and 0.999 6. The limits of detection of phthalate esters in food samples ranged from 0.005 to 0.05 mg/kg (S/N = 3) and the limits of quantification ranged from 0.02 to 0.2 mg/kg (S/N = 10). The average recoveries of 23 analytes spiked in 10 kinds of food matrices ranged from 77% to 112% with the relative standard deviations (RSDs, n = 6) of 4.1%-12.5%. The method is suitable for the determination of 23 phthalate esters simultaneously in foodstuffs with easy operation, high accuracy and precision. PMID:22667087

Zheng, Xianghua; Lin, Liyi; Fang, Enhua; Huang, Yonghui; Zhou, Shuang; Zhou, Yu; Zheng, Xiaoyan; Xu, Dunming

2012-01-01

192

Direct exposure electron ionization mass spectrometry and gas chromatography/mass spectrometry techniques to study organic coatings on archaeological amphorae.  

PubMed

Two different analytical approaches, direct exposure electron ionization mass spectrometry (DE-MS) and gas chromatography/mass spectrometry (GC/MS), were compared in a study of archaeological resinous materials. DE-MS was found to be an efficient fingerprinting tool for the fast screening of organic archaeological samples and for providing information on the major components. GC/MS appeared to be more efficient in unravelling the sample composition at a molecular level, despite the long analysis time and the need for a wet chemical pretreatment. Both procedures were applied to characterize the organic material present as coatings in Roman and Egyptian amphorae. DE-MS successfully identified abietanic compounds, hence a diterpenic resinous material could be identified and its degree of oxidation assessed. GC/MS enabled us to identify dehydroabietic acid, 7-oxodehydroabietic acid, 15-hydroxy-7-oxodehydroabietic acid, 15-hydroxydehydroabietic acid, retene, tetrahydroretene, norabietatriene, norabietatetraene and methyl dehydroabietate. These oxidized and aromatized abietanes provided evidence that the amphorae examined were waterproofed with a pitch produced from resinous wood of plants from the Pinaceae family. The chemometric evaluation of the GC/MS data highlighted significant chemical differences between the pitches found in the two archaeological sites, basically related to differences in the production techniques of the materials and in their degradation pathways. PMID:15739159

Colombini, Maria Perla; Modugno, Francesca; Ribechini, Erika

2005-05-01

193

Solid-phase microextraction and gas chromatography-mass spectrometry for rapid characterisation of semi-hard cheeses.  

PubMed

A headspace solid-phase microextraction (HS-SPME) method in combination with gas chromatography-mass spectrometry (GC-MS) has been used for extraction and identification of components of the volatile fraction of "Provola dei Nebrodi", a typical semi-hard Sicilian cheese. Cheese samples from different producers and at different ripening stages have been examined. The effects of various conditions (e.g. sample volume, sample headspace volume, sample heating temperature, extraction time, etc.) on extraction efficiency were studied in order to optimise the technique. The technique used made it possible to identify 61 components: fatty acids from C(2) to C(14) and their esters, aldehydes, alcohols, methyl ketones, delta-lactones, aromatic compounds, hydrocarbons and terpenes. The main components were butanoic, hexanoic and octanoic acids. The linear free fatty acids (FFA) from C(2) to C(10) were quantified by using the standard addition method. Calibration curves constructed for the FFA spiked into cheese were highly linear with a correlation coefficient R(2) > 0.998. Significant statistical differences (P> or =0.05) were evident for the even-carbon-number fatty acids during ripening. PMID:15700171

Verzera, A; Ziino, M; Condurso, C; Romeo, V; Zappal, M

2004-12-01

194

Optimization of solvent bar microextraction combined with gas chromatography mass spectrometry for preconcentration and determination of tramadol in biological samples.  

PubMed

A simple, rapid and sensitive analytical method for preconcentration and determination of tramadol in different biological samples have been developed using solvent bar microextraction (SBME) combined with gas chromatography-mass spectrometry (GC-MS). The target drugs were extracted from 12 ml of aqueous sample with pH 12.0 (source phase; SP) into an organic extracting solvent (n-nonanol) located inside the pores and lumen of a polypropylene hollow fiber (receiving phase; RP). In order to obtain high extraction efficiency, the effect of different variables on the extraction efficiency was studied using an experimental design. The variables of interest were the type of organic phase, pH of the source phases, ionic strength, volume of the source phase, stirring rate, extraction time and temperature. The experimental parameters of SBME were optimized using a Box-Behnken design (BBD) after a Plackett-Burman screening design. The detection limits were 0.02 ?g L(-1) with 4.5% RSD (n=5, c=10 ?g L(-1)) for tramadol. Finally, the applicability of the proposed method was evaluated by extraction and determination of the drugs in different biological samples. The results indicated that SBME method has excellent clean-up and high-preconcentration factor and can be served as a simple and sensitive method for monitoring of tramadol in the biological samples. PMID:22771254

Ghasemi, Ensieh

2012-08-17

195

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

PubMed

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

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

2014-02-01

196

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

PubMed

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

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

2013-05-01

197

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

PubMed

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

Martnez, C; Gmez, V; Pocurull, E; Borrull, F

2015-01-01

198

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

PubMed

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

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

2013-01-01

199

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

PubMed

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

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

2010-10-01

200

Comparison of gas chromatography/mass spectrometry and immunoassay techniques on concentrations of atrazine in storm runoff  

USGS Publications Warehouse

Gas chromatography/mass spectrometry (GC/MS) and enzyme linked immunosorbent assay (ELISA) techniques were used to measure concentrations of dissolved atrazine in 149 surface-water samples. Samples were collected during May 1992-September 1993 near the mouth of the White River (Indiana) and in two small tributaries of the river. GC/MS was performed on a Hewlett- Packard 5971A with electron impact ionization and selected ion monitoring of filtered water samples extracted by C-18 solid phase extraction: ELISA was performed with a magnetic-particle-based assay with photometric analysis. ELISA results compared reasonably well to GC/MS measurements at concentrations below the Maximum Contaminant Level for drinking water set by the U.S. Environmental Protection Agency (3.0 ??g/L), but a systematic negative bias was observed at higher concentrations. When higher concentration samples were diluted into the linear range of calibration, the relation improved. A slight positive bias was seen in all of the ELISA data compared to the GC/MS results, and the bias could be partially explained by correcting the ELISA data for cross reactivity with other triazine herbicides. The highest concentrations of atrazine were found during the first major runoff event after the atrazine was applied. Concentrations decreased throughout the rest of the sampling period even though large runoff events occurred during this time, indicating that most atrazine loading to surface waters in the study area occurs within a few weeks after application.

Lydy, M.J.; Carter, D.S.; Crawford, C.G.

1996-01-01

201

Different headspace solid phase microextraction--gas chromatography/mass spectrometry approaches to haloanisoles analysis in wine.  

PubMed

Three approaches in determination of six haloanisoles (2,4,6-trichloroanisole, 2,3,4-trichloroanisole, 2,3,6-trichloroanisole, tetrachloroanisole, pentachloroanisole and 2,4,6-tribromoanisole) in wine were compared. Comprehensive gas chromatography - time of flight mass spectrometry (GCGC-ToF-MS) was described for the first time for this application and compared to gas chromatography-tandem mass spectrometry (GC-MS/MS) using triple quadrupole instrument. These techniques were compared with "standard" analytical approach using GC-MS(SIM). SPME method was developed and used for all separation methods (DVB/PDMS fiber, 70 C, 30%NaCl, 20 min extraction). Extraction dependence on matrix was discussed using model wines with different ethanol contents (8%, 12%, and 18%) as well as water and different wines (dry white, dry red and sweet liqueur), with the lowest sensitivities obtained for highest ethanol contents in model wine and for liqueur wine. Limits of detection for GCGC-ToF-MS method were 0.09-2.92 ng/L depending on the examined compound and matrix (compared to 0.1-13.3 ng/L obtained using GC/MS(SIM)). For GC-MS/MS method lower detection limits were achieved than for the GCGC method (0.01-0.1 ng/L), however comprehensive gas chromatography-mass spectrometry provides full spectral information on analyzed compounds. Both methods had limits of detection far below odor thresholds of haloanisoles in wine, good linearity up to 2000 ng/L tested and good precision, what makes them suitable for analysis of these compounds in low ppt levels. PMID:23932370

Jele?, Henryk H; Dziadas, Mariusz; Majcher, Ma?gorzata

2013-10-25

202

Nitrogen isotopic analyses by isotope-ratio-monitoring gas chromatography/mass spectrometry  

NASA Technical Reports Server (NTRS)

Amino acids containing natural-abundance levels of 15N were derivatized and analyzed isotopically using a technique in which individual compounds are separated by gas chromatography, combusted on-line, and the product stream sent directly to an isotope-ratio mass spectrometer. For samples of N2 gas, standard deviations of ratio measurement were better than 0.1% (Units for delta are parts per thousand or per million (%).) for samples larger than 400 pmol and better than 0.5% for samples larger than 25 pmol (0.1% 15N is equivalent to 0.00004 atom % 15N). Results duplicated those of conventional, batchwise analyses to within 0.05%. For combustion of organic compounds yielding CO2/N2 ratios between 14 and 28, in particular for N-acetyl n-propyl derivatives of amino acids, delta values were within 0.25% of results obtained using conventional techniques and standard deviations were better than 0.35%. Pooled data for measurements of all amino acids produced an accuracy and precision of 0.04 and 0.23%, respectively, when 2 nmol of each amino acid was injected on column and 20% of the stream of combustion products was delivered to the mass spectrometer.

Merritt, D. A.; Hayes, J. M.

1994-01-01

203

Modern developments in gas chromatography-mass spectrometry-based environmental analysis.  

PubMed

Gas chromatography coupled with mass spectrometry (GC-MS) continues to play an important role in the identification and quantification of organic contaminants in environmental samples. GC-MS is one of the most attractive and powerful techniques for routine analysis of some ubiquitous organic pollutants due to its good sensitivity and high selectivity and versatility. This paper presents an overview of recent developments and applications of the GC-MS technique in relation to the analysis in environmental samples of known persistent pollutants and some emerging contaminants. The use of different mass analysers such as linear quadrupole, quadrupole ion-trap, double-focusing sectors and time-of-flight analysers is examined. The advantages and limitations of GC-MS methods for selected applications in the field of environmental analysis are discussed. Recent developments in field-portable GC-MS are also examined. PMID:12877169

Santos, F J; Galceran, M T

2003-06-01

204

Structural determination of nerve agent markers using gas chromatography mass spectrometry after derivatization with 3-pyridyldiazomethane.  

PubMed

Nerve agents are a class of organophosphorous chemicals that are prohibited under the Chemical Weapons Convention. Their degradation products, phosphonic acids, are analyzed as markers of nerve agent contamination and use. Because the phosphonic acids are non-volatile and very polar, their identification by GC-MS requires a derivatization step prior to analysis. Standard derivatization methods for gas-chromatography electron-impact mass-spectrometry analysis give very similar spectra for many alkyl phosphonic acid isomers, which complicates the identification process. We present a new reagent, 3-pyridyldiazomethane, for preparing picolinyl ester derivatives of alkyl methylphosphonic acids facilitating the determination of their structure by enhancing predictable fragmentation of the O-alkyl chain. This fragmentation is directed by the nitrogen nucleus of the pyridyl moiety that abstracts hydrogen from the O-alkyl chain, inducing radical cleavage of the carbon-carbon bonds and thereby causing extensive fragmentation that can be used for detailed structure elucidation of the O-alkyl moiety. The separability of related isomers was tested by comparing the spectra of the picolinyl esters formed from twelve hexyl methylphosphonic acid isomers. Spectral library matches and principal component analysis showed that the picolinyl esters were more effectively separated than the corresponding trimethylsilyl derivatives used in the standard operating procedures. The suggested method will improve the unambiguous structural determination process for phosphonic acids. PMID:23832937

Nyholm, Jenny Rattfelt; Gustafsson, Tomas; stin, Anders

2013-07-01

205

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

PubMed

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

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

2009-11-20

206

Chemometric optimization of derivatization reactions prior to gas chromatography-mass spectrometry analysis.  

PubMed

Derivatization is a methodological technique that can be used to make an organic compound more suitable for qualitative and/or quantitative analysis (e.g. pharmaceuticals). However, many analysts try to avoid this analytical procedure as it is time-consuming and labour-intensive. On the other hand, an inter-laboratory study demonstrated that with regard to sensitivity and measurement uncertainty, gas chromatography coupled to mass-spectrometry was superior to liquid chromatography coupled to mass spectrometry for the trace analysis of organic compounds in matrices of greater complexity. In our previous paper (Kumirska et al., J. Chemometr. 25 (2011) 636-643) we suggested using principal component analysis (PCA) to optimize the derivatization of six compounds (5 oestrogenic steroids and diethylstilbestrol) prior to GC-MS analysis. In the present work we applied a highly sophisticated model - 24 pharmaceuticals derived from six classes of drugs. The efficiency of different derivatization reactions was evaluated by PCA and compared with that obtained from cluster analysis (CA), the latter method being applied in this context for the first time. Derivatization using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and 1% trimethylchlorosilane (TMCS) in pyridine and ethyl acetate (2:1:1, v/v/v) for 30min at 60C was found to be optimal. The SPE-GC-MS method was also validated and successfully applied to the analysis of selected pharmaceuticals in wastewater and surface waters in Poland. PMID:23706154

Kumirska, Jolanta; Plenis, Alina; ?ukaszewicz, Paulina; Caban, Magda; Migowska, Natalia; Bia?k-Bieli?ska, Anna; Czerwicka, Ma?gorzata; Stepnowski, Piotr

2013-06-28

207

Simultaneous chiral separation of methylamphetamine and common precursors using gas chromatography/mass spectrometry.  

PubMed

Methylamphetamine, ephedrine, and pseudoephedrine were derivatized using trifluoroacetic anhydride and enantiomers of each were analyzed using gas chromatography coupled to mass spectrometry (GC/MS) fitted with a ?-cyclodextrin (Chiraldex G-PN) chiral column. A temperature-programmed method was developed and optimized and the results compared with those obtained using a previously published isothermal GC method applied to GC/MS analysis. Trifluoroacetylated 3-(trifluoromethyl)phenethylamine hydrochloride was used as an internal standard, and mass fragmentation patterns are proposed for all derivatives analyzed. Qualitative validation of the optimized chromatographic conditions was completed in accordance with the guidelines published by the United Nations Office on Drugs and Crime (UNODC). Under conditions of repeatability and reproducibility, the method gave relative retention times with a relative standard deviation of less than 0.02% for all six analytes of interest. This surpasses the UNODC's acceptance criteria of 2% for validation of qualitative precision. Ephedrine and pseudoephedrine are common precursors in the clandestine manufacture of methylamphetamine. Seizures of illicit methylamphetamine therefore often contain mixtures of these optically active compounds. The simultaneous enantioseparation of these compounds to produce a profile would provide valuable information to law enforcement agencies regarding the provenance of a methylamphetamine seizure. PMID:21780193

Drake, Samantha J; Morrison, Calum; Smith, Frank

2011-09-01

208

High-temperature gas chromatography-mass spectrometry for skin surface lipids profiling[S  

PubMed Central

Skin surface lipids (SSLs) arising from both sebaceous glands and skin removal form a complex lipid mixture composed of free fatty acids and neutral lipids. High-temperature gas chromatography coupled with electron impact or chemical ionization mass spectrometry was used to achieve a simple analytical protocol, without prior separation in classes and without prior cleavage of lipid molecules, in order to obtain simultaneously i) a qualitative characterization of the individual SSLs and ii) a quantitative evaluation of lipid classes. The method was first optimized with SSLs collected from the forehead of a volunteer. More than 200 compounds were identified in the same run. These compounds have been classified in five lipid classes: free fatty acids, hydrocarbons, waxes, sterols, and glycerides. The advantage to this method was it provided structural information on intact compounds, which is new for cholesteryl esters and glycerides, and to obtain detailed fingerprints of the major SSLs. These fingerprints were used to compare the SSL compositions from different body areas. The squalene/cholesterol ratio was used to determine the balance between sebaceous secretion and skin removal. This method could be of general interest in fields where complex lipid mixtures are involved. PMID:20952798

Michael-Jubeli, Rime; Bleton, Jean; Baillet-Guffroy, Arlette

2011-01-01

209

[Determination of endogenous agmatine in rat plasma by isotope dilution-gas chromatography-mass spectrometry].  

PubMed

A method for the determination of endogenous agmatine in rat plasma was developed by isotope dilution-gas chromatography-negative chemical ionization mass spectrometry (GC-NCI/MS). The plasma samples were analyzed after protein precipitation, evaporation, derivatization by hexafluoroacetone (HFAA), and clean-up on a Florisil SPE column. The GC-MS analysis utilized stable isotope d8-agmatine as internal standard. The samples after treatme were tested by negative chemical ionization with selected ion monitoring (SIM) which was set at m/z 492 (molecular ion of agmatine) and m/z 500 (molecular ion of internal standard). The limit of detection (LOD) of agmatine standard solution was 0.005 7 ng/mL. The calibration curve of the agmatine spiked in rat plasma showed a good linear relationship at the range of 1.14-57.0 ng/mL (r = 0.997). The recoveries of agmatine spiked in rat plasma ranged from 92.3% to 109.8%. Inter-day and intra-day precisions were less than 15%. The average concentration level of agmatine in rat plasma was (22 +/- 9) ng/mL, and there was no significant difference between male and female SD rats (p > 0.05). The method is high sensitive and specific, and can be used for the determination of endogenous agmatine in plasma. It provides a strong support for the subsequent research of agmatine. PMID:25255573

Qiu, Zhongli; Lin, Ying; Xiong, Zhili; Xie, Jianwei

2014-07-01

210

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

PubMed Central

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

2010-01-01

211

Integration of Gas Chromatography Mass Spectrometry Methods for Differentiating Ricin Preparation Methods  

SciTech Connect

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 the castor plant Ricinus communis. 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 chromatographic - mass spectrometric (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 and 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.

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

2012-05-17

212

Study on gas chromatography-mass spectrometry fingerprint of Acanthopanax brachypus.  

PubMed

As a peculiar folk medicinal plant, Acanthopanax brachypus was widely used to treat various diseases in China. At present, however, there is not a good quality standard for its quality evaluation. In this study, on the basis of the validation tests of precision, stability and repeatability, the chromatographic fingerprint of A. brachypus was established by using gas chromatography (GC)-flame ionization detector (FID) and GC-MS techniques, as well as computer aided similarity evaluation system. Thirty-two different batches of samples collected from the different producing regions and the different parts of A. brachypus were studied. The results showed that the dominant constituents of all oils were monoterpenes and sesquiterpenes, as well as oxygenated monoterpenes and sesquiterpenes. The fingerprinting profiles were found to be consistent for the fresh stem bark acquired from various production areas, 48 common peaks were determined, but the relative abundance of peaks was varied. ?-Pinene, linalool, p-cymene, spathulenol, camphene, endo-borneol, verbenone, ?-caryophyllene, ?-terpinene, germacrene-D, camphor, ?-thujone and ?-cadinene were the main constituents of the fresh stem bark oil. Except for the leaf, the chemical components among different medicinal parts of fresh plant were inconsistent with the stem bark. Besides, the varieties and relative levels of chemical components in the fresh stem bark were more abundant than in the dry counterpart. The GC-MS fingerprint can be successfully applied to distinguish the substitute or adulterant, and further assess the differences of A. brachypus grown in various areas of China. PMID:24076562

Hu, Haobin; Zheng, Xudong; Hu, Huaisheng; Wang, Ruirui; Wu, Yun

2014-09-01

213

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

214

[Headspace solid-phase microextraction-gas chromatography-mass spectrometry for analysis of volatile components from Atractlodes macrocephala Koidz].  

PubMed

Headspace solid-phase microextraction (HS-SPME) technique was employed to extract the volatile components from Chinese traditional medicine, Atractlodes macrocephala Koidz. The volatile components were isolated and identified successfully by gas chromatography-mass spectrometry (GC-MS). The results from HS-SPME-GC-MS were compared with those obtained from steam distillation-GC-MS (SD-GC-MS) with a good agreement. The volatiles were collected using a polydimethylsiloxane-divinylbenzene (PDMS-DVB) fiber by HS-SPME. The best response was obtained when the extraction temperature was 70 degrees C, the equilibrium time and extraction time were all 30 min and the desorption time was 4 min. Analysis was performed by GC-MS with a polysiloxane capillary column (30 m x 0.25 mm, film thickness 0.25 microm) using He as the carrier gas and a programmed temperature run. Forty-one components accounting for 90.81% were identified. The main components (relative amount more than 1%) of the samples by HS-SPME were atractylone (40.12%), gamma-elemene (14.73%), aromadendrene (13.05%), eudesma-4 (14), 11-diene (5.46%), caryophyllene (2.56%), patchoulene (2.55%), 6,10,11,11-tetramethyl-tricyclo [6.3.0.1(2,3)] undec-7-ene (2.11%), cedrene (1.48%), alpha-caryophyllene (1.48%) and selina-4 (14) -7 (11) diene-8-one (1.01%). By SD-GC-MS, 31 components accounting for 88.19% were identified and all these components could be extracted by SPME except trans-beta-ocimene which accounts only 0.10%. The results showed that the HS-SPME technique can be used to extract the the volatile components from Atractlodes macrocephala Koidz. in place of the traditional time-consuming SD. PMID:17432574

Guo, Fangqiu; Huang, Lanfang; Zhou, Shaoyun

2007-01-01

215

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

USGS Publications Warehouse

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.

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

2004-01-01

216

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

PubMed

A method for analysis of a wide range of odor compounds in aqueous samples at sub-ng mL? to ?g mL? 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 80C 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 25C: log0.54-5.65 mg L?, vapor pressure at 25C: 0.011-3.2 mm Hg) and leaving most of the low volatile matrix behind. The FEDHS-GC-MS method showed good linearity (r>0.9909) and high sensitivity (limit of detection: 0.21-5.2 ng mL?) 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? (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? (RSD<10%, n=6). PMID:22542289

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

2012-06-01

217

Detection of sibutramine administration: a gas chromatography/mass spectrometry study of the main urinary metabolites.  

PubMed

A gas chromatographic/mass spectrometric (GC/MS) study aimed at identifying the metabolites of sibutramine (1-(4-chlorophenyl)-N,N-dimethyl-alpha-(2-methylpropyl)cyclobutanemethanamine) in urine is described. Urinary excretion of sibutramine metabolites following the oral administration of a single dose of sibutramine was followed by GC/MS analysis. After identification of the chromatographic signals corresponding to the six main urinary metabolites, the fragmentation pattern was studied in electron ionization (EI) mode after derivatization to the corresponding methyl and trimethylsilyl derivatives. Urine samples were pretreated according to a reference procedure (liquid/liquid separation, enzymatic hydrolysis, pre-concentration under a stream of nitrogen and derivatization, either under thermal incubation and by microwave irradiation). All sibutramine metabolites were excreted as glucuroconjugates, and retain the chiral carbon present in the sibutramine skeleton. The metabolites identified included mono-desmethylsibutramine (nor-sibutramine), bi-desmethylsibutramine (nor-nor-sibutramine), and the corresponding hydroxylated compounds, the hydroxylation taking place either on the cyclobutane or on the isopropyl chain. The excretion profiles of the different metabolites were also evaluated. From an analytical point of view, the method can be applied to different fields of forensic analytical toxicology, including anti-doping analysis. Although the lack of certified reference materials does not allow a precise determination of the limits of detection (LODs) of all the sibutramine metabolites, an estimation taking into account the response factor of similar compounds ensures that all metabolites are still clearly detectable in a range of concentrations between 10 and 50 ng/mL, thus satisfying the minimum required performance limits (MRPLs) of the World Anti-Doping Agency (WADA). PMID:17154357

Strano-Rossi, Sabina; Colamonici, Cristiana; Botr, Francesco

2007-01-01

218

Identification and quantification of polyfunctionalized hopanoids by high temperature gas chromatographymass spectrometry  

PubMed Central

Hopanoids are triterpenoids produced mainly by bacteria, are ubiquitous in the environment, and have many important applications as biological markers. A wide variety of related hopanoid structures exists, many of which are polyfunctionalized. These modifications render the hopanoids too involatile for conventional gas chromatography (GC) separation, so require either laborious oxidative cleavage of the functional groups or specialized high temperature (HT) columns. Here we describe the systematic evaluation and optimization of a HT-GC method for the analysis of polyfunctionalized hopanoids and their methylated homologs. Total lipid extracts are derivatized with acetic anhydride and no further treatment or workup is required. We show that acid or base hydrolysis to remove di- and triacylglycerides leads to degradation of several BHP structures. DB-XLB type columns can elute hopanoids up to bacteriohopane-tetrol at 350 C, with baseline separation of all 2-methyl/desmethyl homologs. DB-5HT type columns can additionally elute bacteriohopaneaminotriol and bacteriohopaneaminotetrol, but do not fully separate 2-methyl/desmethyl homologs. The method gave 2- to 7-fold higher recovery of hopanoids than oxidative cleavage and can provide accurate quantification of all analytes including 2-methyl hopanoids. By comparing data from mass spectra with those from a flame ionization detector, we show that the mass spectromet (MS) response factors for different hopanoids using either total ion counts or m/z 191 vary substantially. Similarly, 2-methyl ratios estimated from selected-ion data are lower than those from FID by 1030% for most hopanoids, but higher by ca. 10% for bacteriohopanetetrol. Mass spectra for a broad suite of hopanoids, including 2-methyl homologs, from Rhodopseudomonas palustris are presented, together with the tentative assignment of several new hopanoid degradation products. PMID:24496464

Sessions, Alex L.; Zhang, Lichun; Welander, Paula V.; Doughty, David; Summons, Roger E.; Newman, Dianne K.

2013-01-01

219

Combination of TLC blotting and gas chromatography-mass spectrometry for analysis of peroxidized cholesterol.  

PubMed

We have established a sensitive and convenient method for analysis of cholesterol hydroperoxides (Chol-OOHs) as trimethylsilyloxyl derivatives using diphenylpyrenylphosphine (DPPP)-thin-layer chromatography (TLC) blotting and gas chromatography-electron ionization-mass spectrometry/selected-ion monitoring (GC-EI-MS/SIM). Chol-OOH standards were prepared by photosensitized oxidation and azo radical-induced peroxidation of cholesterol. Trimethylsilyloxyl derivatives of cholesterol 5alpha-hydroperoxide (Chol 5alpha-OOH), cholesterol 7alpha-hydroperoxide (Chol 7alpha-OOH), and cholesterol 7beta-hydroperoxide (Chol 7beta-OOH) could be separated from one another in the SIM chromatogram using a fragment ion with elimination of trimethylsilanol from the molecular ion. This method was used to characterize peroxidized cholesterol from azo radical-exposed human low-density lipoprotein and UVA-irradiated human keratinocytes in the presence of hematoporphyrin. Finally, we succeeded in the quantification of each Chol-OOH isomer present in hairless mouse skin with and without UVA irradiation by use of beta-sitosterol hydroperoxide as internal standard. The accumulation of Chol 5alpha-OOH with Chol 7alpha/betaOOH in the skin indicates that singlet molecular oxygen ((1)O(2)) participated in the peroxidation of skin cholesterol, because Chol 5alpha-OOH is known to be a (1)O(2) specific cholesterol peroxidation product. We concluded that the combination of DPPP-TLC blotting and GC-EI-MS/SIM is useful for quantifying peroxidized cholesterol in biological samples and confirming the participation of (1)O(2) in oxidative stress. PMID:17701239

Minami, Yuko; Yokoi, Sayuri; Setoyama, Mari; Bando, Noriko; Takeda, Sayaka; Kawai, Yoshichika; Terao, Junji

2007-11-01

220

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

PubMed Central

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

2011-01-01

221

Gas chromatography/mass spectrometry based component profiling and quality prediction for Japanese sake.  

PubMed

Sake is a Japanese traditional alcoholic beverage, which is produced by simultaneous saccharification and alcohol fermentation of polished and steamed rice by Aspergillus oryzae and Saccharomyces cerevisiae. About 300 compounds have been identified in sake, and the contribution of individual components to the sake flavor has been examined at the same time. However, only a few compounds could explain the characteristics alone and most of the attributes still remain unclear. The purpose of this study was to examine the relationship between the component profile and the attributes of sake. Gas chromatography coupled with mass spectrometry (GC/MS)-based non-targeted analysis was employed to obtain the low molecular weight component profile of Japanese sake including both nonvolatile and volatile compounds. Sake attributes and overall quality were assessed by analytical descriptive sensory test and the prediction model of the sensory score from the component profile was constructed by means of orthogonal projections to latent structures (OPLS) regression analysis. Our results showed that 12 sake attributes [ginjo-ka (aroma of premium ginjo sake), grassy/aldehydic odor, sweet aroma/caramel/burnt odor, sulfury odor, sour taste, umami, bitter taste, body, amakara (dryness), aftertaste, pungent/smoothness and appearance] and overall quality were accurately explained by component profiles. In addition, we were able to select statistically significant components according to variable importance on projection (VIP). Our methodology clarified the correlation between sake attribute and 200 low molecular components and presented the importance of each component thus, providing new insights to the flavor study of sake. PMID:25060729

Mimura, Natsuki; Isogai, Atsuko; Iwashita, Kazuhiro; Bamba, Takeshi; Fukusaki, Eiichiro

2014-10-01

222

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

PubMed

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

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

2015-01-01

223

On the conversion of a mass selective detector from gas chromatography\\/mass spectrometry application to stand-alone, on-line, real-time mass spectrometry application  

Microsoft Academic Search

Development of initial versions of hardware and software for a Hewlett-Packard HP-5971A mass selective detector (MSD) was performed in order to improve its capabilities for monitoring gaseous waste streams. The development allowed for initial evaluation of the feasibility of the conversion of the MSD from an integrated gas chromatography\\/mass spectrometry (GC-MS) detector to a stand-alone, on-line, real-time mass spectrometry (SOR-MS)

M. Koch

1994-01-01

224

Application of solid-phase microextraction combined with gas chromatographymass spectrometry to the determination of butylated hydroxytoluene in bottled drinking water  

Microsoft Academic Search

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 packages contents. A method for the determination of BHT in water by means of solid-phase microextraction and gas chromatographymass spectrometry has been

Norma B Tombesi; Hugo Freije

2002-01-01

225

Development of a method for analysis of Iranian damask rose oil: Combination of gas chromatographymass spectrometry with Chemometric techniques  

Microsoft Academic Search

Gas chromatographymass spectrometry (GCMS) combined with Chemometric resolution techniques were proposed as a method for the analysis of volatile components of Iranian damask rose oil. The essential oil of damask rose was extracted using hydrodistillation method and analyzed with GCMS in optimized conditions. A total of 70 components were identified using similarity searches between mass spectra and MS database. This

Mehdi Jalali-Heravi; Hadi Parastar; Hassan Sereshti

2008-01-01

226

Correlating sensory attributes to gas chromatographymass spectrometry profiles and e-nose responses using partial least squares regression analysis  

Microsoft Academic Search

Sensory scores for 15 attributes identified in soy sauce aroma by quantitative descriptive analysis were correlated with purge and trap gas chromatographymass spectrometry (GCMS) profiles and electronic nose (e-nose) responses using partial least squares (PLS) regression analysis. Highly predictive PLS models were obtained for every attribute based on whole GCMS profiles. However, the predictability has been greatly improved in the

Tetsuo Aishima

2004-01-01

227

Determination of malondialdehyde in human blood by headspace-solid phase micro-extraction gas chromatographymass spectrometry after derivatization with 2,2,2-trifluoroethylhydrazine  

Microsoft Academic Search

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 chromatographymass spectrometry (HS-SPME-GCMS) was described for the determination of malondialdehyde (MDA) in blood. Acetone-d6 was used as internal standard. MDA and acetone d6 in blood reacted for 40min at 50C with 2,2,2-trifluoroethylhydrazine in headspace

Ho-Sang Shin

2009-01-01

228

Analysis of poly(vinyl chloride) and other polymers in sediments and suspended matter of a coastal lagoon by pyrolysis-gas chromatography-mass spectrometry  

Microsoft Academic Search

Pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) was used for the analysis of synthetic polymers in core sediments and suspended particulate matter (SPM) of the coastal lagoon Pialassa Baiona (Adriatic Sea). Pyrograms exhibited a multitude of peaks deriving from the thermal degradation of natural organic matter (humic substances, planktonic material), artificial resins and synthetic rubbers. Upon pyrolysis, sediments generated high levels of styrene

Daniele Fabbri; Daniele Tartari; Claudio Trombini

2000-01-01

229

Determination of geosmin and 2-methylisoborneol in water and wine samples by ultrasound-assisted dispersive liquidliquid microextraction coupled to gas chromatographymass spectrometry  

Microsoft Academic Search

A fast, simple and environmentally friendly ultrasound-assisted dispersive liquidliquid microextraction (USADLLME) procedure has been developed to preconcentrate geosmin and 2-methylisoborneol (MIB) from water and wine samples prior to quantification by gas chromatographymass spectrometry (GCMS). A two-stage multivariate optimization approach was developed by means of a PlackettBurman design for screening and selecting the significant variables involved in the USADLLME procedure, which

Carol Cortada; Lorena Vidal; Antonio Canals

2011-01-01

230

A Microscale Technique for Gas Chromatography-Mass Spectrometry Measurements of Picogram Amounts of Indole3Acetic Acid in Plant Tissues  

Microsoft Academic Search

A microscale technique has been developed for routine quanti- fications of picogram amounts of indole-3-acetic acid (IAA) in plant tissues by combined gas chromatography-mass spectrometry. Low- and high-resolution selected-ion-monitoring and selected-reaction- monitoring mass spectrometry techniques were compared for selectivity and precision. The best selectivity was obtained with selected-reaction-monitoring analysis, and 1 -mg samples containing 500 fg of IAA could be

Agneta Edlund; Staffan Eklof; Bjorn Sundberg; Thomas Moritz; Goran Sandberg

231

Development of a gas chromatographymass spectrometry method for the determination of pesticides in gaseous and particulate phases in the atmosphere  

Microsoft Academic Search

A reliable multi-residue method for determining gaseous and particulate phase pesticides in atmospheric samples has been developed. This method, based on full scan gas chromatographymass spectrometry (GCMS), allowed the proper determination of sixteen relevant pesticides, in a wide range of concentrations and without the influence of interferences. The pesticides were benfluralin, bitertanol, buprofezin, chlorfenvinphos, chlorpyrifos, chlorpyrifos-methyl, ethalfluralin, fenthion, lindane, malathion,

E. Borrs; P. Snchez; A. Muoz; L. A. Tortajada-Genaro

2011-01-01

232

Hollow Fiber Liquid-Phase Microextraction Combined with Gas Chromatography-Mass Spectrometry for Determination of Root Exudated Potential Allelochemicals in Capsicum Annuum(Chilli)  

Microsoft Academic Search

Hollow fiber liquid phase microextraction (HF-LPME) was developed for the determination of potential allelochemicals by gas chromatography-mass spectrometry (GC-MS). Biomass method was applied to study allelopathic effect. The applicability of the proposed procedure was evaluated through extraction three potential allelochemicals in re-circulating hydroponic culture solution of chilli. The parameters affecting extraction efficiency were studied and optimized. The optimum extraction conditions

Haiyan Sun; Yan Wang

2012-01-01

233

Rapid and simple determination of psychotropic phenylalkylamine derivatives in human hair by gas chromatographymass spectrometry using micro-pulverized extraction  

Microsoft Academic Search

A gas chromatographymass spectrometric (GCMS) method was developed and validated for the determination of five psychotropic phenylalkylamine derivatives (amphetamine, AP; methamphetamine, MA; 3,4-methylenedioxyamphetamine, MDA; 3,4-methylenedioxymethamphetamine, MDMA; norketamine, NKT) in human hair. Hair samples (10mg) were washed with distilled water and acetone, mechanically pulverized for 1.5min with a bead mill, and then incubated in 1mL of methanol under ultrasonication at 50C

Jin Young Kim; Soon Ho Shin; Jae Il Lee; Moon Kyo In

2010-01-01

234

Simple and sensitive determination of ? 9-tetrahydrocannabinol, cannabidiol and cannabinol in hair by combined silylation, headspace solid phase microextraction and gas chromatographymass spectrometry  

Microsoft Academic Search

A new method for determination of ?9-tetrahydrocannabinol (THC), cannabidiol (CBD) and cannabinol (CBN) in hair based on alkaline hair hydrolysis, extraction by iso-octane, combined derivatization with N,O-bis-(trimethylsilyl)-trifluoroacetamide and headspace solid phase microextraction of the extract residue, and gas chromatographymass spectrometry was developed and evaluated. The limits of detection of the three compounds were 0.010.02ng\\/mg. The method was routinely applied to

Thomas Nadulski; Fritz Pragst

2007-01-01

235

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

USGS Publications Warehouse

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

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

2014-01-01

236

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

NASA Astrophysics Data System (ADS)

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.

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.; Prvt, A. S. H.; O'Dowd, C. D.; Hoffmann, T.

2014-07-01

237

Determination of alkyl amines in atmospheric aerosol particles: a comparison of gas chromatography-mass spectrometry and ion chromatography approaches  

NASA Astrophysics Data System (ADS)

In recent years low molecular weight alkyl amines 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 alkyl amines 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 alkyl amines in aerosol particles. Alkyl amines 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. For the IC approach, a solid phase extraction (SPE) column was used to separate alkyl amines 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 alkyl amines on the IC column. The limits of detection obtained are 2.1-15.9 ng 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 alkyl amines due to its lower detection limits and higher accuracy.

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

2014-03-01

238

[Serum metabolome by gas chromatography-mass spectrometry (GC-MS) in patients with ulcerative colitis and celiac disease].  

PubMed

Metabolomics is the emerging science of measurement and analysis of metabolome--the complete set of low molecular weight compounds in a cell, tissue, organ or whole organism. One of the aims of metabolomics is to research the response of an organism to a pathophysiological insult by measuring the concentrations of small molecule metabolites in biofluids and tissues and its dynamics. Intestinal microbiota is most probably involved in the development and maintenance of autoimmune inflammation in ulcerative colitis and celiac disease. Gas chromatography-mass spectrometry (GC - MS) of serum generates comprehensive metabolic profiles, reflecting integrated human (systemic) and gut microbial metabolism which may be altered in disease states. The aim of this study was to investigate GC - MS-based serum metabolomic profiles in UC and CD patients. Serum metabolic profiles were collected from 75 individuals: 20 patients with mild-moderate active UC, 35 CD patients, and 20 healthy controls (HC). We characterized 84 serum metabolites by use GC-MS. 18 metabolites at least have a combined (human + microbial) origin. In serum of UC patients, phenylacetic acid (PAA), 4-hydroxyphenylacetic acid (4-HPAA), 3-indolylacetic acid (IAA), succinic acid (SA) and fumaric acid (FA) were the metabolites most prominently increased, whereas 3-phenylpropionic acid (PPA) was significantly decreased. Serum of CD patients showed significant increases in IAA, 3-indolepropionic acid (IPA), SA and FA. Increased serum levels of succinic acid suggest its possible damaging effect on intestinal mucosa especially in ulcerative colitis. Orally administered butyrate + inulin as supplement to mesalazine in UC or gluten free diet in CD was effective in reducing disease activity with a marked improvement of serum metabolomic profiles (including SA reduction) and gut microbiota in both diseases. There were no any adverse events. PMID:24933989

Sitkin, S I; Tkachenko, E I; Vakhitov, T Ia; Oreshko, L S; Zhigalova, T N

2013-01-01

239

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

PubMed Central

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

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

2012-01-01

240

Gas chromatography-mass spectrometry-based profiling of serum fatty acids in acetaminophen-induced liver injured rats.  

PubMed

In this study, we have developed and validated a simple, accurate and sensitive gas chromatography-mass spectrometry (GC-MS) method for simultaneous quantification of 18 fatty acids in rat serum, including both non-esterified (NEFA) and esterified (EFA) fatty acids, and subsequent analysis of fatty acid metabolic profiles. This novel method was used to evaluate the serum levels of fatty acids from vehicle- and acetaminophen (APAP)-treated rats. Serum levels of 7 NEFAs and 14 EFAs were significantly higher in APAP-treated rats 24 h after APAP administration at 1500 mg kg? when compared with vehicle-treated controls. Control and APAP-treated rats could be differentiated based on their metabolic profiles using two different chemometric analysis methods: principle component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA). More importantly, we identified the following NEFAs as potential biomarkers of APAP-induced liver injury: oleic acid (C18:1n9), linoleic acid (C18:2n6), docosahexaenoic acid (C22:6n3) and arachidonic acid (C20:4n6). The serum concentrations of C18:1n9, C18:2n6 and C22:6n3 were all positively correlated (r?>?0.8; Pearson's correlation analysis) with the activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). These results suggest that a novel targeted metabolomics method based on the metabolic profiling of fatty acids analyzed by GC-MS provides exact serum concentrations of fatty acids as well as a prospective methodology to evaluate chemically induced hepatotoxicity. PMID:23239188

Xiong, Yin-Hua; Xu, Ying; Yang, Li; Wang, Zheng-Tao

2014-02-01

241

Simultaneous determination of six hydrophilic ethers at trace levels using coconut charcoal adsorbent and gas chromatography/mass spectrometry.  

PubMed

The main objective of the following study was to determine the efficiency of a method that uses coconut charcoal as a solid-phase extraction (SPE) adsorbent in order to simultaneously detect six hydrophilic ether species in water in the low microgram-per-liter range. The applied method was validated for quantification of ethyl tert-butyl ether, 1,4-dioxane, ethylene glycol dimethyl ether (monoglyme), diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme) and tetraethylene glycol dimethyl ether (tetraglyme). SPE followed by gas chromatography/mass spectrometry of the extracts using the selected ion monitoring mode allowed for establishing low detection limits in the range of 0.007-0.018 ?g/L in ultrapure water and 0.004-0.020 ?g/L in environmental samples. Examination of the method accuracy and precision resulted in a recovery greater than 86.8 % for each compound with a relative standard deviation of less than 6.6 %. A stability study established a 5-day holding time for the unpreserved water samples and extracts. Finally, 27 samples obtained from surface water bodies in Germany were analyzed for the six hydrophilic ethers. Each analyte was detected in at least eight samples at concentrations reaching 2.0 ?g/L. The results of this study emphasize the advantage of the method to simultaneously determine six hydrophilic ether compounds. The outcome of the surface water analyses augments a concern about their frequent and significant presence in surface water bodies in Germany. PMID:23232954

Stepien, D K; Pttmann, W

2013-02-01

242

Pyrolysis-gas chromatography/mass spectrometry identification of distinctive structures providing humic character to organic materials.  

PubMed

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 the initial noncomposted wastes and several reference humic and fulvic acids from soils were analyzed. These results were compared with results from previous studies using 13C-cross polarization magic angle spinning-nuclear magnetic resonance (NMR), UV-visible, and fluorescence emission spectroscopies. Alkylbenzenes and alkylphenols predominate in the pyrograms of the soil humic acids, whereas the fulvic acids showed higher contents of phenolic and polysaccharide-derived compounds. The pyrolysates of THE from the composted samples showed an increase in aromatic and nitrogenated structures and a decrease in polysaccharide-derived compounds. The aromatic contents as determined by Py-GC/MS and 13C-NMR were well correlated in the reference humic substances and THE from composted materials (r = 0.99 and 0.94, respectively; P < 0.01) but not in the case of THE from noncomposted materials, probably due to an aliphatic enhancement in the pyrolysates of these samples and other secondary reactions. The content in alkylbenzenes was consistent with the variations found previously for several UV-visible and fluorescence indexes as a function of the degree of humification, suggesting their involvement in structures that are a characteristic feature of the formation and evolution of humic substances. PMID:20830935

Fuentes, Marta; Baigorri, Roberto; Gonzlez-Vila, Francisco J; Gonzlez-Gaitano, Gustavo; Garca-Mina, Jos M

2010-01-01

243

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

PubMed

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 oxazepam), antidepressant drugs (amitryptiline, paroxetine and sertraline), antipsychotic drugs (haloperidol, chlorpromazine and fluphenazine) chlormethiazole, loratidine, hydroxyzine, diphenhydramine, valproic acid and gabapentin. After the addition of deuterated analogues of morphine, 3,4-methylenedioxymethamphetamine, (+/-)-11-nor-9-carboxy-delta-9-tetrahydrocannabinol and clonazepam as internal standards, all the compounds were simultaneously extracted from oral fluid by solid-phase extraction procedure. Acid compounds were eluted with acetone while basic and neutral compounds with dichloromethane:isopropanol:ammonium (80:20:2, v/v/v). Chromatography was performed on a methylsilicone capillary column and analytes, derivatized with N-Methyl-N-(trimethylsilyl)trifluoroacetamide, were determined in the selected-ion-monitoring (SIM) mode. Mean recovery ranged between 44.5 and 97.7 % and quantification limit between 0.9 and 44.2 ng/ml oral fluid for the different analytes. The developed analytical methodology was applied to investigate the presence of psychoactive drugs in oral fluid from injured individuals attending the emergency room (MACIUS project). PMID:17395417

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

2007-06-28

244

Determination of perfluorodecalin and perfluoro-N-methylcyclohexylpiperidine in rat blood by gas chromatography-mass spectrometry.  

PubMed

A gas chromatography-mass spectrometry method (SIM mode) was developed for the determination of perfluorodecalin (cis and trans isomers, 50% each) (FDC), and perfluoromethylcyclohexylpiperidine (3 isomers) (FMCP) in rat blood. The chromatographic separation was performed by injection in the split mode using a CP-select 624 CB capillary column. Analysis was performed by electronic impact ionization. The ions m/z 293 and m/z 181 were selected to quantify FDC and FMCP due to their abundance and to their specificity, respectively. The ion m/z 295 was selected to monitor internal standard. Before extraction, blood samples were stored at -30 degrees C for at least 24 h in order to break the emulsion. The sample preparation procedure involved sample clean-up by liquid-liquid extraction. The bis(F-butyl)ethene was used as the internal standard. For each perfluorochemical compound multiple peaks were observed. The observed retention times were 1.78 and 1.87 min for FDC, and 2.28, 2.34, 2.48 and 2.56 min for FMCP. For each compound, two calibration curves were used; assays showed good linearity in the range 0.0195-0.78 and 0.78-7.8 mg/ml for FDC, and 0.00975-0.39 and 0.39-3.9 mg/ml for FMCP. Recoveries were 90 and 82% for the two compounds, respectively with a coefficient of variation <8%. Precision ranged from 0.07 to 15.6%, and accuracy was between 89.5 and 111.4%. The limits of quantification were 13 and 9 microg/ml for FDC and FMCP, respectively. This method has been used to determine the pharmacokinetic profile of these two perfluorochemical compounds in blood following administration of 1.3 g of FDC and 0.65 g of FMCP per kg body weight, in emulsion form, in rat. PMID:11043752

Audran, M; Krafft, M P; De Ceaurriz, J; Maturin, J C; Sicart, M T; Marion, B; Bougard, G; Bressolle, F

2000-08-18

245

Differentiation of South American crack and domestic (US) crack cocaine via headspace-gas chromatography/mass spectrometry.  

PubMed

South American 'crack' cocaine, produced directly from coca leaf, can be distinguished from US domestically produced crack on the basis of occluded solvent profiles. In addition, analysis of domestically produced crack indicates the solvents that were used for cocaine hydrochloride (HCl) processing in South America. Samples of cocaine base (N=3) from South America and cocaine from the USA (N=157 base, N=88 HCl) were analyzed by headspace-gas chromatography-mass spectrometry (HS-GC-MS) to determine their solvent profiles. Each cocaine HCl sample was then converted to crack cocaine using the traditional crack production method and re-examined by HS-GC-MS. The resulting occluded solvent profiles were then compared to their original HCl solvent profiles. Analysis of the corresponding crack samples confirmed the same primary processing solvents found in the original HCl samples, but at reduced levels. Domestically seized crack samples also contained reduced levels of base-to-HCl conversion solvents. In contrast, analysis of South American crack samples confirmed the presence of low to high boiling hydrocarbons and no base-to-HCl conversion solvents. The presented study showed analysis of crack cocaine samples provides data on which processing solvents were originally utilized in the production of cocaine HCl in South America, prior to conversion to crack cocaine. Determination of processing solvents provides valuable information to the counter-drug intelligence community and assists the law enforcement community in determining cocaine distribution and trafficking routes throughout the world. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. PMID:25303034

Colley, Valerie L; Casale, John F

2014-10-01

246

Gas chromatography-mass spectrometry assessment of amines in Port wine and grape juice after fast chloroformate extraction/derivatization.  

PubMed

A simple, reliable, and sensitive gas chromatography-mass spectrometry method for the quantification of volatile and nonvolatile biogenic amines in Port wines and grape juices was developed and evaluated. The method was based on a previously reported two-phase derivatization procedure with isobutyl chloroformate in a toluene medium, which provides a quantitative reaction in 10 min. Following the derivatization step, the excess of reagent was eliminated by treatment with alkaline methanol. The derivatization procedure was performed directly on 1 mL of sample, avoiding any fastidious and time-consuming cleanup extraction steps. The method allows the simultaneous quantification of 22 amines, which can be found in wines: methylamine, dimethylamine, ethylamine, diethylamine, propylamine, isopropylamine, butylamine, isobutylamine, amylamine, isoamylamine, 2-methylbutylamine, hexylamine, pyrrolidine, piperidine, morpholine, 1,3-diaminopropane, putrescine, cadaverine, 1,6-diaminohexane, 2-phenylethylamine, histamine, and tyramine. Because of the fact that histamine and tyramine derivatives are degraded during the isobutyl chloroformate elimination step, the corresponding determination was made after removal of the excess of derivatizing reagent by evaporating an aliquot of the toluene layer obtained after the reaction. The presented method showed excellent analytical characteristics in what linearity, recovery, repeatability, and limit of detections were respected. It was used to assess the concentration of biogenic amines in juice grapes and Tawny and Vintage Port wines with different aging times. On the whole, the total content of amines in Port wines was low. Most of the amines found in wines have their origin in the raw material used for their elaboration, so the Port winemaking process is not prone to the production of this kind of compounds. Total biogenic amine contents have shown a decrease with the aging of both types of Port wines. PMID:21732693

Cunha, S C; Faria, M A; Fernandes, J O

2011-08-24

247

Chemometric Analysis of Gas Chromatography Mass Spectrometry Data using Fast Retention Time Alignment via a Total Ion Current Shift Function  

SciTech Connect

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.

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

2010-04-15

248

Simultaneous analysis of urinary phthalate metabolites of residents in Korea using isotope dilution gas chromatography-mass spectrometry.  

PubMed

Phthalates are used in industry products, household items, and medical tools as plasticizers. Human exposure to phthalates has raised concern about its toxicity. In the present study, optimization was conducted for the simultaneous analysis of eight kinds of phthalate metabolites using gas chromatography-mass spectrometry (GC-MS): MEP, MiBP, MnBP, MBzP, MiNP, MEHP, MEOHP, and MEHHP. In order to minimize the matrix effect and to do quantitative analysis, isotope dilution and LLE-GC-MS methods were performed. Urine samples were enzymatically hydrolyzed, extracted with a mixture of n-hexane and ethyl ether (8:2; v:v), and subsequently derivatized with trimethylsilylation. All eight kinds of analytes showed clear resolution and high reproducibility in GC-MS results. The method detection limit ranged from 0.05 ng/mL to 0.2 ng/mL. Calibration curves were found to be linear from 0.2 to 100 ng/mL with -(2)>0.992. The relative standard deviation of the intraday precision using water and urine ranged from 2.1% to 16.3%. The analysis was performed with urine samples that were collected from adults residing in the Republic of Korea. The analyzed concentration results were compared according to gender and region. As a result, DEHP metabolites showed the highest detected concentration (75.92 ?g/g creatinine, 100%), and MiNP, a metabolite of DiNP, showed the lowest detected concentration (0.42 ?g/g creatinine, 22.5%). On average, female urine (200.76 ?g/g creatinine) had a higher detected concentration of ?8 phthalate metabolites than male urine. Samples from rural regions (211.96 ?g/g creatinine) had higher levels than samples from urban regions. PMID:23928369

Kim, Miok; Song, Na Rae; Choi, Jong-Ho; Lee, Jeongae; Pyo, Heesoo

2014-02-01

249

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

NASA Astrophysics Data System (ADS)

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.

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

2011-04-01

250

Pharmacokinetic study of eight coumarins of Radix Angelicae Dahuricae in rats by gas chromatography-mass spectrometry.  

PubMed

A sensitive, specific gas chromatography-mass spectrometry (GC-MS) method was established for the quantitative determination of eight coumarins of Radix Angelicae Dahuricae including coumarin, isopsoralen, psoralen, xanthotoxin, bergapten, osthole, imperatorin and oxypeucedanin in rat plasma. Nitrendipine was used as the internal standard (IS). The plasma samples were extracted by acetonitrile. GC separation was accomplished on a DB-5MS column with temperature programmed from 160C (17 min) to 190C (10 min) at the rate of 20C/min, then to 240C (5 min) at 20C/min, and finally to 280C (14 min) at 20C/min. The detection was performed on a quadrupole mass spectrometer detector operated by full-scan mode (m/z 50-500). The lower limit of quantitation was 5-10 ng/mL for eight coumarins, and the linear range was 5-1000 ng/mL for the coumarins (R(2)>0.9990). All the validation data were within the required limits. After oral administration, the plasma concentration-time curves showed that the time for maximum concentration (Tmax) was 1.29 for coumarin, 1.83 for isopsoralen, 1.93 for psoralen, 1.30 for xanthotoxin, 2.04 for bergapten, 0.64 for osthole, 1.41 for imperatorin and 0.51 h for oxypeucedanin. The plasma concentration of the eight coumarins was low, with a mean maximum plasma concentration (Cmax) <6.41 ?g/mL. Pharmacokinetic data analysis showed that the eight coumarins had different pharmacokinetic characteristics after oral administration. The method was successfully applied to pharmacokinetic studies of eight coumarins after oral administration in rats. PMID:23774663

Zhao, Gang; Peng, Cheng; Du, Wei; Wang, Sicen

2013-09-01

251

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

SciTech Connect

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).

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

252

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

PubMed

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

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

2012-06-01

253

Studying species composition of microbial communities with the use of gas chromatography-mass spectrometry: microbial community of kaolin  

Microsoft Academic Search

The composition of microbial communities has been investigated avoiding conventional cultural techniques by chromatography-mass spectrometric analysis of chemical signature markers. Concentrations of fatty acids, hydroxy acids, aldehydes, sterols, and methanolysate of the biomass lipid fractions were used to determine the population size of the individual community members. The calculation is based on the information stored in a data bank about

George A. Osipov; Evgenia S. Turova

1997-01-01

254

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

PubMed

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

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

2014-10-01

255

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

PubMed

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

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

2015-03-01

256

Bicyclic naphthenic acids in oil sands process water: Identification by comprehensive multidimensional gas chromatography-mass spectrometry.  

PubMed

Although bicyclic acids have been reported to be the major naphthenic acids in oil sands process-affected water (OSPW) and a well-accepted screening assay indicated that some bicyclics were the most acutely toxic acids tested, none have yet been identified. Here we show by comprehensive multidimensional gas chromatography-mass spectrometry (GCGC-MS), that >100 C8-15 bicyclic acids are typically present in OSPW. Synthesis or purchase allowed us to establish the GCGC retention times of methyl esters of numerous of these and the mass spectra and published spectra of some additional types, allowed us to identify bicyclo[2.2.1]heptane, bicyclo[3.2.1]octane, bicyclo[4.3.0]nonane, bicyclo[3.3.1]nonane and bicyclo[4.4.0]decane acids in OSPW and a bicyclo[2.2.2]octane acid in a commercial acid mixture. The retention positions of authentic bicyclo[3.3.0]octane and bicyclo[4.2.0]octane carboxylic acid methyl esters and published retention indices, showed these were also possibilities, as were bicyclo[3.1.1]heptane acids. Bicyclo[5.3.0]decane and cyclopentylcyclopentane carboxylic acids were ruled out in the samples analysed, on the basis that the corresponding alkanes eluted well after bicyclo[4.4.0]decane (latest eluting acids). Bicyclo[4.2.1]nonane, bicyclo[3.2.2]nonane, bicyclo[3.3.2]decane, bicyclo[4.2.2]decane and spiro[4.5]decane carboxylic acids could not be ruled out or in, as no authentic compounds or literature data were available. Mass spectra of the methyl esters of the higher bicyclic C12-15 acids suggested that many were simply analogues of the acids identified above, with longer alkanoate chains and/or alkyl substituents. Our hypothesis is that these acids represent the biotransformation products of the initially somewhat more bio-resistant bicyclanes of petroleum. Although remediation studies suggest that many bicyclic acids can be relatively quickly removed from suitably treated OSPW, examination by GCGC-MS may show which isomers are affected most. Knowledge of the structures will allow the toxicity of any residual isomers to be calculated and measured. PMID:25553910

Wilde, Michael J; West, Charles E; Scarlett, Alan G; Jones, David; Frank, Richard A; Hewitt, L Mark; Rowland, Steven J

2015-01-23

257

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

NASA Astrophysics Data System (ADS)

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 600C 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 100C to 900C with a 100C 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 100C only water contribution can be detected. Then the number of compounds released increases with the temperature up to 600C. With the temperature increase the nature of the gaseous species detected does not change significantly. Pyrrole was not detected until the temperature exceeds 600C for (5:95) sample and 400C for (10:90) sample. Benzene has also been detected at 800C for the (5:95) sample and 700C for (10:90) sample. In the same way, toluene has been detected for the (10:90) sample at 700C 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-Gonzlez, 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.

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

2013-12-01

258

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

USGS Publications Warehouse

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.

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

2006-01-01

259

Methylation analysis of complex carbohydrates in small amounts: capillary gas chromatography-mass fragmentography of methylalditol acetates obtained from N-glycosidically linked glycoprotein oligosaccharides.  

PubMed

A version of the methylation analysis of complex carbohydrates by gas chromatography-mass spectrometry of the methylalditol acetates (H. Bjrndal, C. G. Hellerquist, B. Lindberg, and S. Svensson (1970) Angew. Chem. 82, 643-674) is described. With this version 100- to 500-pmol samples of N-glycosidically linked glycoprotein oligosaccharides may be analyzed. The method is based on the use of capillary columns which allow the separation of all partially methylated alditol acetates potentially obtained from this group of oligosaccharides and on their selective and sensitive detection by mass fragmentography after chemical ionization with ammonia. PMID:6638480

Geyer, R; Geyer, H; Khnhardt, S; Mink, W; Stirm, S

1983-08-01

260

DETERMINATION OF CHLORFENVINPHOS, FIPRONIL AND CYPERMETHRIN RESIDUES IN MEAT AND BOVINE FAT USING QUECHERS METHOD AND GAS CHROMATOGRAPHY-MASS SPECTROMETRY  

Microsoft Academic Search

Analytic methods were applied and validated to measure residues of chlorfenvinphos, fipronil and cypermethrin in meat and bovine fat, using the QuEChERS method and gas chromatography-mass spectrometry. For the meat, 2g of sample, 4mL of acetonitrile, 1.6g of MgSO4 and 0.4g of NaCl were used in the liquid-liquid partition, while 80mg of C18, 80mg of primary and secondary amine and

Natlia Ceclia Sartarelli; Adriana Nori de Macedo; Juliana Pane de Sousa; Ana Rita de Araujo Nogueira; Silvia Helena Govoni Brondi

2012-01-01

261

DETERMINATION OF CHLORFENVINPHOS, FIPRONIL, AND CYPERMETHRIN RESIDUES IN MEAT AND BOVINE FAT USING QUECHERS METHOD AND GAS CHROMATOGRAPHY-MASS SPECTROMETRY  

Microsoft Academic Search

Analytic methods were applied and validated to measure residues of chlorfenvinphos, fipronil, and cypermethrin in meat and bovine fat, using the QuEChERS method and gas chromatography-mass spectrometry. For the meat, 2g of sample, 4mL of acetonitrile, 1.6g of MgSO4, and 0.4g of NaCl were used in the liquid-liquid partition, while 80mg of C18, 80mg of primary and secondary amine and

Natlia Ceclia Sartarelli; Adriana Nori de Macedo; Juliana Pane de Sousa; Ana Rita de Araujo Nogueira; Silvia Helena Govoni Brondi

2012-01-01

262

Screening volatile organic compounds (VOCs) emissions from five marine phytoplankton species by head space gas chromatography/mass spectrometry (HS-GC/MS).  

PubMed

Five marine cosmopolitan phytoplankton species namely; Calcidiscus leptoporus, Emiliania huxleyi, Phaeodactylum tricornutum, Chaetoceros neogracilis and Dunaliella tertiolecta were screened for emissions of selected VOCs using head space gas chromatography/mass spectrometry (HS-GC/MS) in single ion mode. The VOCs investigated included isoprene and various halogenated compounds. Among the different algae groups, the two diatoms Ch. neogracilis and P. tricornutum were the strongest emitters of methyl bromide (CH3Br), and Ch. neogracilis was the strongest emitter of isoprene. Furthermore, we present evidence that several chlorinated organic compounds, normally considered as anthropogenic, can be produced from marine phytoplankton (namely chloroform, dichloromethane, trichloroethylene, tetrachloroethylene, chlorobenzene and dichlorobenzene). PMID:18392274

Colomb, Aurlie; Yassaa, Noureddine; Williams, Jonathan; Peeken, Ilka; Lochte, Karin

2008-03-01

263

Evaluation of the QuEChERS Method and Gas ChromatographyMass Spectrometry for the Analysis Pesticide Residues in Water and Sediment  

PubMed Central

A method for the determination of pesticide residues in water and sediment was developed using the QuEChERS method followed by gas chromatography mass 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 0.003mgL?1 and 0.02mgkg?1, respectively. PMID:21165598

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

2010-01-01

264

Differentiation of the volatile profile of microbiologically contaminated canned tomatoes by dynamic headspace extraction followed by gas chromatography-mass spectrometry analysis.  

PubMed

The aromatic profile of microbiologically contaminated canned tomatoes was analyzed by the dynamic headspace extraction technique coupled with gas chromatography-mass spectrometry. Canned tomatoes contaminated with Escherichia coli, Saccharomyces cerevisiae and Aspergillus carbonarius were analyzed after 2 and 7 days. About 100 volatiles were detected, among which alcohols, aldehydes and ketones were the most abundant compounds. Gas chromatographic peak areas were used for statistical purposes. First, principal component analysis was carried out in order to visualize data trends and clusters. Then, linear discriminant analysis was performed in order to detect the set of volatile compounds ables to differentiate groups of analyzed samples. Five volatile compounds, i.e. ethanol, beta-myrcene, o-methyl styrene, 6-methyl-5-hepten-2-ol and 1-octanol, were found to be able to better discriminate between uncontaminated and contaminated samples. Prediction ability of the calculated model was estimated to be 100% by the "leave-one-out" cross-validation. An electronic nose device was then used to analyze the same contaminated and not contaminated canned tomato samples. Preliminary results were compared with those obtained by dynamic headspace gas chromatography-mass spectrometry, showing a good agreement. PMID:19064076

Bianchi, F; Careri, M; Mangia, A; Mattarozzi, M; Musci, M; Concina, I; Falasconi, M; Gobbi, E; Pardo, M; Sberveglieri, G

2009-01-15

265

Use of greatly-reduced gas flows in flow-modulated comprehensive two-dimensional gas chromatography-mass spectrometry.  

PubMed

The present research is specifically based on the use of greatly-reduced gas flows, in flow-modulator (FM) comprehensive two-dimensional gas chromatography systems. In particular, focus of the present research is directed to FM devices characterized by an accumulation stage, and a much briefer re-injection step. It has been widely accepted that the operation of such FM systems requires high gas flows (?20mL/min), to re-inject the gas-phase contents of sample (or accumulation) loops, onto the second column. On the contrary, it will be herein demonstrated that much lower gas flows (? 6-8mL/min) can efficiently perform the modulation step of re-injection. The possibility of using such improved operational conditions is given simply by a fine optimization of the processes of accumulation and re-injection. The application of lower gas flows not only means that second-dimension separations are carried out under better analytical conditions, but, even more importantly, greatly reduces problems which arise when using mass spectrometry (i.e., sensitivity and instrumental pumping capacity). PMID:25108766

Tranchida, Peter Q; Franchina, Flavio A; Dugo, Paola; Mondello, Luigi

2014-09-12

266

Quantitative determination of the NMDA antagonist cis-4-phosphonomethyl-2-piperidine carboxylic acid (CGS 19755) in human plasma using capillary gas chromatography/mass spectrometry.  

PubMed

An analytical method has been developed and validated for the quantitative determination of the N-methyl-D-aspartate (NMDA) antagonist cis-4-phosphonomethyl-2-piperidine carboxylic acid (CGS 19755) in human plasma. It is a member of a new class of compounds with the potential to be neuroprotective and attenuate neuronal damage resulting from brain trauma caused by stroke and head trauma. The method is based on gas chromatography/mass spectrometry and uses stable-isotope labeled CGS 19755 as the internal standard. Samples (1 ml) were first acidified (pH 2), then extracted using a solid-phase aminopropyl ion exchange column. The drug was eluted with NH4OH and evaporated until dry. Extracts were derivatized with a mixture of pentafluoropropionic anhydride and pentafluoropropanol, and analyzed by gas chromatography/mass spectrometry. Separation was accomplished on a DB-225 capillary column (15 m x 0.32 mm) with a 0.25 micron film thickness. Mass spectrometry was carried out under negative ion ammonia chemical ionization conditions with selected ion monitoring at m/z 760 and 764 for derivatized CGS 19755 and the internal standard, respectively. Specificity was shown by the lack of interfering peaks at the retention time of CGS 19755 and internal standard. Recovery and reproducibility assessments show good accuracy, precision and linearity over the validated concentration range of 2-5000 ng ml-1. PMID:7948048

Hayes, M J; Khemani, L; Powell, M L

1994-09-01

267

Molecularly imprinted solid-phase extraction for the selective determination of methamphetamine, amphetamine, and methylenedioxyphenylalkylamine designer drugs in human whole blood by gas chromatography-mass spectrometry.  

PubMed

A novel method is described for the extraction of methamphetamine, amphetamine, and methylenedioxyphenylalkylamine designer drugs, such as 3,4-methylenedioxy-methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxyethylamphetamine, N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine, and 3,4-(methylenedioxyphenyl)-2-butanamine, from human whole blood using molecularly imprinted solid-phase extraction as highly selective sample clean-up technique. Whole blood samples were diluted with 10 mmol/L ammonium acetate (pH 8.6) and applied to a SupelMIP-Amphetamine molecularly imprinted solid-phase extraction cartridge. The cartridge was then washed to eliminate interferences, and the amphetamines of interest were eluted with formic acid/methanol (1:100, v/v). After derivatization with trifluoroacetic anhydride, the analytes were quantified using gas chromatography-mass spectrometry. Recoveries of the seven amphetamines spiked into whole blood were 89.1-102%. The limits of quantification for each compound in 200 ?L of whole blood were between 0.25 and 1.0 ng. The maximum intra- and inter-day coefficients of variation were 9.96 and 13.8%, respectively. The results show that methamphetamine, amphetamine, and methylenedioxyphenylalkyl-amine designer drugs can be efficiently extracted from crude biological samples such as whole blood by molecularly imprinted solid-phase extraction with good reproducibility. This extraction method will be useful for the pretreatment of human samples before gas chromatography-mass spectrometry. PMID:22271670

Kumazawa, Takeshi; Hasegawa, Chika; Hara, Kenji; Uchigasaki, Seisaku; Lee, Xiao-Pen; Seno, Hiroshi; Suzuki, Osamu; Sato, Keizo

2012-03-01

268

On the metabolism of the amphetamine-derived antispasmodic drug mebeverine: gas chromatography-mass spectrometry studies on rat liver microsomes and on human urine.  

PubMed

We describe gas chromatography-mass spectrometry studies of the metabolism of the antispasmodic drug mebeverine [Duspatal, (MB)]. MB is the veratric acid (VA) ester of 4-ethyl-[2-(4-methoxyphenyl)-1-methylethyl]aminobutan-1-ol (MB-OH), which is an N-substituted ethylamphetamine derivative. The metabolites were first identified in rat liver microsome incubates and then detected in urine samples of volunteers through the use of electron impact and positive chemical ionization gas chromatography-mass spectrometry. Urinary conjugates were enzymatically cleaved before analysis. The following phase I metabolites of MB could be identified: VA, O-demethyl VA (vanillic and/or isovanillic acid), O-bisdemethyl VA (protocatechuic acid), MB-OH, hydroxy MB-OH, O-demethyl MB-OH, O-demethyl-hydroxy MB-OH, N-desethyl MB-OH, N-desethyl-O-demethyl MB-OH, N-de(hydroxybutyl) MB-OH (methoxy-ethylamphetamine), N-de(hydroxybutyl)-O-demethyl MB-OH (hydroxy-ethylamphetamine), and N-bisdealkyl MB-OH (p-methoxy-amphetamine, known as the designer drug PMA). The following, partly overlapping metabolic pathways of MB could be postulated: ester hydrolysis, O-demethylation, ring hydroxylation, N-deethylation, and N-de(hydroxybutylation). The latter pathway led to ethylamphetamine derivatives and bisdealkylation led to PMA, which are substances of forensic interest. The metabolites containing alcoholic or phenolic hydroxy groups were partly excreted into urine as conjugates. PMID:10681380

Kraemer, T; Bickeboeller-Friedrich, J; Maurer, H H

2000-03-01

269

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

PubMed

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

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

2014-11-25

270

Hydrogen Sulfide Measurement by Headspace-gas Chromatography-mass Spectrometry (HS-GC-MS): Application to Gaseous Samples and Gas Dissolved in Muscle.  

PubMed

The aim of our study was to present a new headspace-gas chromatography-mass spectrometry (HS-GC-MS) method applicable to the routine determination of hydrogen sulfide (H2S) concentrations in biological and gaseous samples. The primary analytical drawback of the GC/MS methods for H2S measurement discussed in the literature was the absence of a specific H2S internal standard required to perform quantification. Although a deuterated hydrogen sulfide (D2S) standard is currently available, this standard is not often used because this standard is expensive and is only available in the gas phase. As an alternative approach, D2S can be generated in situ by reacting deuterated chloride with sodium sulfide; however, this technique can lead to low recovery yield and potential isotopic fractionation. Therefore, N2O was chosen for use as an internal standard. This method allows precise measurements of H2S concentrations in biological and gaseous samples. Therefore, a full validation using accuracy profile based on the ?-expectation tolerance interval is presented. Finally, this method was applied to quantify H2S in an actual case of H2S fatal intoxication. PMID:25336379

Varlet, Vincent; Giuliani, Nicole; Palmiere, Cristian; Maujean, Graldine; Augsburger, Marc

2015-01-01

271

Evaluation of leaf-derived extracts as an environmentally sustainable source of essential oils by using gas chromatography-mass spectrometry and enantioselective gas chromatography-olfactometry.  

PubMed

In consideration of the world's present environmental situation and the threat of species extinction, investigations concerning alternative sustainable sources of natural substances represent an extremely important issue. In this respect, the present research is focused on the analytical evaluation of Brazilian rosewood (Aniba rosaeodora Ducke) leaves, as an alternative source (with respect to wood) of rosewood essential oil and, as such, of natural linalool, which is extensively used in perfumery. Enantioselective-gas chromatography-olfactometry (Es-GC-O) was used as a tool for the simultaneous stereodifferentiation and olfactive evaluation of the volatile optically active components present in the analyzed samples. In addition to Es-GC-O analyses, direct olfactive analyses were also performed, enabling the evaluation of the global aroma exerted by each sample and the influence of each linalool antipode, as also other minor compounds. The samples were also submitted to gas chromatography-mass spectrometric analysis, thus establishing their chemical profiles. The assessment of enantiopure chiral compounds through Es-GC-O, along with direct olfactive analyses, confirmed that the leaves are a potential substituent for wood in the extraction of Brazilian rosewood essential oil, representing a sustainable nonwood source of natural linalool. PMID:16448064

d'Acampora Zellner, Barbara; Lo Presti, Maria; Barata, Lauro Euclides Soares; Dugo, Paola; Dugo, Giovanni; Mondello, Luigi

2006-02-01

272

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

PubMed

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

Seisonen, Sirli; Kivima, Evelin; Vene, Kristel

2015-02-15

273

Cloud point extraction with surfactant derivatization as an enrichment step prior to gas chromatographic or gas chromatography-mass spectrometric analysis.  

PubMed

Cloud point extraction (CPE) using Triton X-114 was successfully applied as an extractive preconcentration step prior to gas chromatographic-mass spectrometric analysis. No liquid chromatographic or back-extraction steps were required to remove the target analyte(s) from the surfactant-rich extractant phase. Instead a post-extraction derivatization step is employed in which the surfactant of the surfactant-rich phase is reacted with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) prior to injection into the gas chromatograph. Such derivatization of the Triton X-114 surfactant following CPE was found to provide improved chromatographic performance yielding a reasonable elution time window that is free of derivatized surfactant signals, reproducible analyte retention times, and quantitative results. Mixtures of polycyclic aromatic hydrocarbons (PAHs), herbicides, and profens were utilized to demonstrate the feasibility and performance of this approach. The retention times of six PAHs (acenaphthene, acenaphthylene, anthracene, biphenyl, dibenzofuran, and fluorene) were found to be very reproducible with relative standard deviations (RSDs) in the range of 0.5-0.8%. Quantitative gas chromatography-mass spectrometry (GC/MS) analysis of a herbicide test mixture (composed of alachlor, atrazine, butachlor, hexachlorocyclopentadiene, metolachlor, and simazine) following their CPE from spiked water samples yielded detection limits in the range of 6.6-97 ng/L (except for that of hexachlorocyclopentadiene which was 482 ng/L). The enrichment factors achieved for these herbicides ranged from 17 to 33. The recovery of the herbicides from spiked water samples ranged from 90 to 100% except for simazine and atrazine which were 50% and 74%, respectively. The BSFTA derivatization step can serve not only to derivatize the surfactant but also appropriate nonvolatile (or less volatile) analytes. An ibuprofen and flurbiprofen test mix was utilized to demonstrate this feature. The proposed protocol offers an attractive alternative means by which surfactant-mediated extractions can be utilized as an enrichment step prior to gas chromatographic or gas chromatographic-mass spectrometric analysis of analytes which should serve to expand the scope of CPE in gas chromatographic (GC) analysis. PMID:19621897

Takagai, Yoshitaka; Hinze, Willie L

2009-08-15

274

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

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

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

2015-01-01

275

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

PubMed

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

Wu, Xin; Li, Yubo; Xu, Daoqing; Zhou, Hong; Wang, Jinlei; Guo, Xuejun; Zhang, Yanjun

2015-01-01

276

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

PubMed

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

Panighel, Annarita; Flamini, Riccardo

2014-01-01

277

A quasi non-destructive approach for amber geological provenance assessment based on head space solid-phase microextraction gas chromatography-mass spectrometry.  

PubMed

Head space (HS) solid-phase micro-extraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS) was used to analyze the volatile fraction of ambers of different geological origin. In particular, Romanian (romanite) and Baltic (succinite) amber samples were studied. Both types of amber have nearly similar bulk chemical compositions and could probably reflect only some differences of paleobiological and/or diagenetic origin. The present study shows that amber head space fingerprint, obtained by SPME/GC-MS, can provide a simple and quasi non-destructive method capable of romanite/succinite differentiation. Among the numerous compounds present in the head space, a number of few informative variables could be selected that were able to differentiate the ambers as demonstrated by Principal Component and Cluster Analysis. PMID:24401437

van der Werf, I D; Aresta, A; Truic?, G I; Radu, G L; Palmisano, F; Sabbatini, L

2014-02-01

278

Identification of volatile degradation products from Baltic amber by headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry.  

PubMed

The aim of this study was to test and develop techniques for the detection and identification of volatile compounds released as degradation products by Baltic amber. During a preliminary investigation, the off-gassing of acidic volatiles was detected through the corrosion of lead coupons. The corrosive compounds released by the material were then identified as formic acid and acetic acid by headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry. During an advanced investigation, based on the use of artificial ageing to initiate degradation of model amber samples in different microclimates, the detected formic acid and acetic acid off-gassing appeared to be more intense in a dry environment with normal oxygen concentration. The release of formic and acetic acids by the amber was likely the result of radical reactions which should be investigated in further studies. PMID:21107974

Pastorelli, Gianluca; Glastrup, Jens

2011-01-01

279

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

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

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

2015-01-01

280

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

NASA Astrophysics Data System (ADS)

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.

Chiantore, Oscar; Riedo, Chiara; Scalarone, Dominique

2009-07-01

281

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

USGS Publications Warehouse

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

Choi, Y.; Lee, H.W.; Fountain, S.T.; Lubman, D.M.

1994-01-01

282

Acidic metabolite profiling analysis of catecholamine and serotonin as O-ethoxycarbonyl/tert-butyldimethylsilyl derivatives by gas chromatography-mass spectrometry.  

PubMed

A novel derivatization method was developed for the simultaneous determination of six acidic metabolites of catecholamine and serotonin by gas chromatography-mass spectrometry (GC-MS). The metabolites were converted to O-ethoxycarbonyl/tert-butyldimethylsilyl (EOC/TBDMS) derivatives for the direct GC-MS analysis in selected ion monitoring mode. Their mass spectral pattern as EOC/TBDMS derivatives showed characteristic fragment ions of [M - 15](+) and [M - 57](+), which permitted rapid and accurate structural confirmation of acidic metabolites. The present method was linear (r ? 0.998), reproducible (percentage relative standard deviation = 1.0-10.0) and accurate (% relative error = -9.7-9.8) with detection limits of 0.001-4.7 ng/mL. When applied to human urine samples, the method allowed simultaneous determination of six acidic metabolites of catecholamine and serotonin. PMID:22777873

Nguyen, Duc-Toan; Cho, In-Seon; Kim, Jeong-Whun; Kim, Kyoung-Rae; Lee, Gwang; Paik, Man-Jeong

2013-02-01

283

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

PubMed

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

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

2014-11-28

284

Development and application of a method for analysis of phthalates in ham sausages by solid-phase extraction and gas chromatography-mass spectrometry.  

PubMed

A gas chromatography-mass spectrometry assay was developed and successfully applied for the determination of phthalates in ham sausage migrated from packaging film. The phthalates studied were dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), benzylbutyl phthalate (BBP), bis(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DNOP), with dibutyl adipate (DBA) as internal standard. The sample pre-treatments included extraction with n-hexane, solvent evaporation and reconstitution with acetonitrile before and after solid-phase extraction (SPE). The extraction and cleaning up procedure was carried out with cartridges containing dimethyl butylamine groups, which showed extraction efficiencies over 87.3%. The calibration curves obtained were linear with correlation coefficients greater than 0.99. The method proved to be accurate and precise for the six phthalates used. It was successfully applied to a study on the migration of phthalates from packaging PVC film into ham sausage. PMID:20374814

Guo, Zhiyong; Wang, Sui; Wei, Danyi; Wang, Meili; Zhang, Huina; Gai, Panpan; Duan, Jing

2010-03-01

285

Molecularly imprinted fibers with renewable surface for solid-phase microextraction of triazoles from grape juice samples followed by gas chromatography mass spectrometry analysis.  

PubMed

This paper describes the synthesis and characterization of a new molecularly imprinted solid-phase microextraction fiber able to renew its selective binding sites because of the gradual thermal decomposition of the polymeric network. The injector of the chromatograph operates at 300 C, and during the desorption step of the analytes (in a short period), the polymeric network is degraded from the surface to the core in volatile compounds that do not interfere with the analysis. The renewable MIP fiber was successfully employed to extract triazole fungicides (triadimenol, tebuconazole, and metconazole) from grape juice samples followed by gas chromatography mass spectrometry analysis. The method was adjusted to the quadratic models from 100 to 2000 ?g L(-1), with good precision and accuracy. The limits of quantification (100 ?g L(-1) for all analytes) were sufficient to analyze triadimenol, tebuconazole, and metconazole in grape juice samples, where their maximum residue limits in Brazil are 100, 2000, and 1000 ?g L(-1), respectively. PMID:24317365

Freitas, Lissara Aparecida de Souza; Vieira, Andr Coutinho; Mendona, Joo Antnio Felipe Risolia; Figueiredo, Eduardo Costa

2014-02-01

286

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

SciTech Connect

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.

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

1994-05-01

287

Determination of butylated hydroxytoluene in food samples by high-performance liquid chromatography with ultraviolet detection and gas chromatography/mass spectrometry.  

PubMed

A reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed and compared with a gas chromatography/mass spectrometry (GC/MS) method for determining butylated hydroxytoluene (BHT) in foodstuffs as a result of migration from plastic packaging. Similar extraction procedures were used in both methods. BHT was quantitated using an external standard in the HPLC method and an internal standard in the GC/MS method. Both methods presented good linearity (r(2) > or = 0.9917) and low detection limits. Recoveries obtained with the HPLC method (chicken meat, 95.8%, and Gouda cheese, 83.9%) were better than with the GC/MS method (chicken meat, 85.6%, and Gouda cheese, 71.3%). PMID:17373461

Sanches-Silva, Ana; Cruz, Jos M; Sendn-Garca, Raquel; Paseiro-Losada, Perfecto

2007-01-01

288

Fast analysis of principal volatile compounds in crude and processed Atractylodes macrocephala by an automated static headspace gas chromatography-mass spectrometry  

PubMed Central

Objective: Atractylodes macrocephala, a famous herbal medicine, is used extensively in the practice of Traditional Chinese Medicine (TCM). Processing procedure is a common approach that usually occurs before A. macrocephala is prescribed. This paper describes a sensitive and specific assay for the determination of principal volatile compounds in crude and processed A. macrocephala. Materials and Methods: The present study concentrated on the development of a static headspace gas chromatography-mass spectrometry (SHS-GC/MS) for separating and identifying of volatile compounds from crude and processed A. macrocephala samples. Results: The results showed that the volatile oil in crude and processed A. macrocephala was markedly quantitatively and qualitatively different. Processing resulted in the reduction of volatile oil contents and variation of chemical compositions in A. macrocephala. Conclusion: The proposed method proved that SHS-GC/MS is rapid and specific, and should also be useful for evaluating the quality of crude and processed medicinal herbs. PMID:25210311

Zhang, Jida; Cao, Gang; Xia, Yunhua; Wen, Chengping; Fan, Yongsheng

2014-01-01

289

Identification of volatiles in leaves of Alpinia zerumbet 'Variegata' using headspace solid-phase microextraction-gas chromatography-mass spectrometry.  

PubMed

Alpinia zerumbet 'Variegata' is an aromatic medicinal plant, its foliage producing an intense, unique fragrant odor. This study identified 46 volatile compounds in the leaf tissue of this plant using headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The major compounds included 1, 8-cineole (43.5%), p-cymene (14.7%), humulene (5.5%), camphor (5.3%), linalool (4.7%), (E)-methyl cinnamate (3.8%), gamma-cadinene (3.3%), humulene oxide II (2.1%) and a-terpineol (1.5%). The majority of the volatiles were terpenoids of which oxygenated monoterpenes were the most abundant, accounting for 57.2% of the total volatiles. Alcohols made up the largest (52.8%) and aldehydes the smallest (0.2%) portions of the volatiles. Many bioactive compounds were present in the volatiles. PMID:25230513

Chen, Jian Yan; Ye, Zheng Mei; Huang, Tian Yi; Chen, Xiao Dan; Li, Yong Yu; Wu, Shao Hua

2014-07-01

290

Determination of musty odorants, 2-methylisoborneol and geosmin, in environmental water by headspace solid-phase microextraction and gas chromatography--mass spectrometry.  

PubMed

A simple and sensitive method for the determination of musty odorants, 2-methylisoborneol (MIB) and geosmin (GSM), in environmental water was developed by headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry. MIB and GSM were separated within 10 min using a DB-1 capillary column and detected in the selective ion monitoring mode. HS-SPME using a polydimethylsiloxane/divinylbenzene fiber provided effective sample enrichment, and was carried out by fiber exposition at 70 degrees C for 30 min. Using this method, the calibration curves of MIB and GSM were linear in the range of 0-500 pg/mL, with a correlation coefficient above 0.9977 (n=24). The detection limits (S/N=3) of MIB and GSM were 0.9 and 0.6 pg/mL, respectively. This method was successfully applied to the analysis of environmental water samples without interference peaks. PMID:18207154

Saito, Keita; Okamura, Kota; Kataoka, Hiroyuki

2008-04-01

291

Microwave irradiation for a fast gas chromatography-mass spectrometric analysis of polysaccharide-based plasma volume expanders in human urine.  

PubMed

In this contribution we tested the possibility to use microwave irradiation for the screening and confirmation pre-treatment steps of hydroxyethylstarch, with the aim to speed up gas chromatography-mass spectrometric procedures. Acid hydrolysis and derivatization processes were conducted in a temperature-controlled single beam microwave oven for organic synthesis. The kinetics of hydroxyethylstarch chemical hydrolysis and derivatization were investigated at different microwave power, incubation temperature and incubation time. The best hydrolysis conditions were found at a microwave power value of 1200 W (T 100C) with an incubation time of 2 min; whereas the best derivatization conditions were found at a microwave power value of 1020 W (T 100C) with an incubation time of 5 min. The effectiveness of this approach was evaluated by gas chromatography-mass spectrometry analyzing more than 20 different pools of blank urine samples spiked with hydroxyethylstarch at a concentration of 1 mg/mL. The results showed that the effect of microwave irradiation on the chemical hydrolysis process was very remarkable: the total sample preparation time can be shortened by 58 min compared to the reference method (2 min instead of 60 min). In addition to this, the time necessary for the derivatization process can also be drastically shortened with respect to the reference procedure (5 min instead of 30 min). The repeatability of the hydrolysis and derivatization recoveries, the limit of detection and the matrix interferences were comparable to the reference method accredited under the ISO 17025 guidelines and presently followed by the accredited sports anti-doping laboratory of Rome. PMID:20889391

Mazzarino, Monica; De Angelis, Francesca; Di Cicco, Teresa; de la Torre, Xavier; Botr, Francesco

2010-11-01

292

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...

293

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

EPA Science Inventory

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

294

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

EPA Science Inventory

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

295

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...

296

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

PubMed

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

Niebler, Johannes; Buettner, Andrea

2015-01-01

297

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

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

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

2014-08-01

298

Resolution of volatile fuel compound profiles from Ascocoryne sarcoides: a comparison by proton transfer reaction-mass spectrometry and solid phase microextraction gas chromatography-mass spectrometry  

PubMed Central

Volatile hydrocarbon production by Ascocoryne sacroides was studied over its growth cycle. Gas-phase compounds were measured continuously with a proton transfer reaction-mass spectrometry (PTR-MS) and at distinct time points with gas chromatography-mass spectrometry (GC-MS) using head space solid phase microextraction (SPME). The PTR-MS ion signal permitted temporal resolution of the volatile production while the SPME results revealed distinct compound identities. The quantitative PTR-MS results showed the volatile production was dominated by ethanol and acetaldehyde, while the concentration of the remainder of volatiles consistently reached 2,000 ppbv. The measurement of alcohols from the fungal culture by the two techniques correlated well. Notable compounds of fuel interest included nonanal, 1-octen-3-ol, 1-butanol, 3-methyl- and benzaldehyde. Abiotic comparison of the two techniques demonstrated SPME fiber bias toward higher molecular weight compounds, making quantitative efforts with SPME impractical. Together, PTR-MS and SPME GC-MS were shown as valuable tools for characterizing volatile fuel compound production from microbiological sources. PMID:22480438

2012-01-01

299

Pathway of diethyl phthalate photolysis in sea-water determined by gas chromatography-mass spectrometry and compound-specific isotope analysis.  

PubMed

The degradation mechanism of diethyl phthalate (DEP) in natural seawater under UV irradiation was investigated using a combination of intermediates detection and determination of stable carbon isotopic fractionation. Typical intermediates identified with gas chromatography-mass spectrometry (GC-MS) were mono-ethyl phthalate (MEP) and phthalic anhydride. Stable carbon isotope signature was determined by gas chromatography coupled with isotope ratio mass spectrometry through a combustion interface (GC-C-IRMS). A profound (13)C enrichment, with a ?(13)C isotope shift of 12.30.3 (f=0.09) in residual DEP molecule, was clearly an indicator to its photolysis. The reactive position isotope enrichment factor (?(reactive position)) and apparent kinetic isotope effects (AKIE) were -35.252.26 and 1.075, respectively, indicating that the initial reaction step was cleavage of a CO bond in DEP photolysis. Based on these observations, a degradation pathway was proposed. First, a CO bond in DEP molecule was broken to form MEP. Then, MEP was further degraded to phthalic anhydride. Our work demonstrates that compound-specific isotope analysis (CSIA), when combined with intermediates analysis, is a reliable measure to deduce the mechanism of DEP photolysis. This approach might be extended as a reference for mechanism investigation in complicated environment systems. PMID:22883110

Peng, Xuewei; Feng, Lijuan; Li, Xianguo

2013-01-01

300

Application of gas chromatography-cryocondensation-Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry to the identification of gas phase reaction products from the alpha-pinene/ozone reaction.  

PubMed

The gas phase reaction of alpha-pinene with the atmospheric oxidant ozone was investigated by using the capabilities of both gas chromatography-cryocondensation-Fourier transform infrared spectroscopy (GC-FT-IR) and gas chromatography-mass spectrometry (GC-MS), for the identification of the reaction products formed. The reaction was carried out in a flow reaction chamber from where the compounds were sampled on Tenax-containing adsorption cartridges. The reaction mixture was injected onto the column after thermodesorption and analyzed using both GC-IR and GC-MS. Twenty compounds could be detected, including the reactant alpha-pinene and it's impurities tricyclene and camphene. Eleven compounds were identified by spectra comparison with either reference data or spectra obtained from commercial standards. Four compounds were tentatively identified from their IR and MS spectra, while from the remaining two compounds the nature of basic functional groups could be established. PMID:10669298

Schrader, W; Geiger, J; Hoffmann, T; Klockow, D; Korte, E H

1999-12-24

301

Identification of the more complex triacylglycerols in bovine milk fat by gas chromatography-mass spectrometry using polar capillary columns.  

PubMed

The fourth most volatile 2.5% molecular distillate of butteroil obtained by redistillation of the most volatile 10% cut was examined by gas chromatography on a polar capillary column (RSL-300) with electron impact and chemical ionization mass spectrometry. For this purpose the distillate was first freed from the acetyldiacylglycerols by thin-layer chromatography on plain silica gel and the remainder resolved into long and short chain length saturates, cis- and trans-monoenes, dienes and trienes by thin-layer chromatography on silver nitrate-silica gel. The order of gas chromatographic elution was established for more than 100 major and minor species making up the bulk of the molecular distillate. The results were used to derive the quantitative composition of the triacylglycerol species making up the various peaks obtained by polar capillary column gas chromatography of the total molecular distillate, which closely resembles the lower half of the molecular mass distribution of whole bovine milk fat. PMID:3243860

Myher, J J; Kuksis, A; Marai, L; Sandra, P

1988-10-28

302

Determination of BROMATE AT PARTS-PER-TRILLION LEVELS BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY WITH NEGATIVE CHEMICAL IONIZATION  

EPA Science Inventory

The ozonation of bromide-containing source waters produces bromate as a class 2B carcinogenic disinfection by-product. The present work describes the determination of bromate by gas chromatography-negative chemical ionization mass spectrometry (GC-NCIMS) following a bromate react...

303

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

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 1-200ngg(-1), with a correlation coefficient (R(2)) higher than 0.98. Limits of detection and limits of quantification were 0.15-0.3ngg(-1) and 0.47-1ngg(-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

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

2015-05-01

304

Use of L-[(15)N] glutamic acid and homoglutathione to determine both glutathione synthesis and concentration by gas chromatography-mass spectrometry (GCMS).  

PubMed

A method for simultaneous measurement of both glutathione enrichment and concentration in a biological sample using gas chromatography mass spectrometry is described. The method is based on the preparation of N,S-ethoxycarbonylmethyl ester derivatives of glutathione, and the use of homoglutathione (glutamyl-cysteinyl--alanine) as an internal standard. A procedure for determination of glutamate concentration and enrichment is also reported. Both methods have within-day and day-to-day inter-assay coefficients of variation less than 5%, and recoveries of known added amounts of glutathione and glutamate are close to 100%. Taken together, these methods allowed determination of glutathione concentration and fractional synthesis rate in red blood cells using L-[(15)N] glutamic acid infusion. This approach was applied in vivo to investigate the effects of a 72 h fast, compared with a control overnight fast, on erythrocyte glutathione in a single dog. The 72 h fast was associated with a 39% decline in erythrocyte glutathione level, (2.9 +/- 0.4 versus 4.7 +/- 0.5 mmol l(-1), fasting versus control) with no change in glutathione fractional synthesis (67.4 versus 71.3% d(-1), fasting versus control). PMID:11473395

Humbert, B; Nguyen, P; Obled, C; Bobin, C; Vaslin, A; Sweeten, S; Darmaun, D

2001-07-01

305

Determination of aromatic amines in human urine using comprehensive multi-dimensional gas chromatography mass spectrometry (GCxGC-qMS).  

PubMed

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

Lamani, Xolelwa; Horst, Simeon; Zimmermann, Thomas; Schmidt, Torsten C

2015-01-01

306

Development of a screening method for the analysis of organic pollutants in water using dual stir bar sorptive extraction-thermal desorption-gas chromatography-mass spectrometry.  

PubMed

The development of a method for screening of organic compounds with a wide range of physico-chemical properties in water, based on dual stir bar sorptive extraction coupled with thermal desorption and gas chromatography-mass spectrometry (dual SBSE-TD-GC-MS) is described. The investigated water sample is divided into two aliquots and extracted with stir bar sorptive extraction at two different conditions: using addition of methanol or sodium chloride, respectively. Following extraction, the two stir bars are inserted into the same glass thermal desorption liner and are simultaneously desorbed and analysed by GC-MS. The method optimisation was performed using 45 environmentally harmful substances with different volatilities (boiling point from 193 to 495C), polarity (logK(ow) from 2.17 to 8.54) and acido-basic properties. The majority of model compounds was selected from the EU list of priority substances in the field of water policy and from the US EPA method 625, respectively. Optimisation was performed for extraction parameters (sample volume, extraction time, stirring rate, addition of modifiers) as well as for the thermal desorption conditions (desorption flow, desorption time, cryofocusing temperature). Performance characteristics (recovery, repeatability, carryover, linearity, limits of detection and quantification) were determined for the optimised method. An example of analysis of a contaminated groundwater sample is presented. PMID:22099662

Tlgyessy, Peter; Vrana, Branislav; Krascsenits, Zoltn

2011-12-15

307

Studies on the human metabolism and the toxicologic detection of the cough suppressant dropropizine in urine using gas chromatography-mass spectrometry.  

PubMed

Studies are described on the metabolism and the toxicologic analysis of the nonopioid cough suppressant dropropizine [R,S-3-(4-phenyl-1-piperazinyl)1,2-propandiol, DRO] in human urine using gas chromatography-mass spectrometry (GC-MS). The metabolism studies showed that DRO was metabolized in humans mainly by hydroxylation of the aromatic ring, by N-dealkylation of the parent drug and of the hydroxyl-metabolite to the corresponding N-phenylpiperazines, and by degradation of the piperazine moiety. The authors' systematic toxicologic analysis (STA) procedure using full-scan GC-MS after acid hydrolysis, liquid-liquid extraction, and microwave-assisted acetylation allowed the unambiguous detection of DRO and its above-mentioned metabolites in human urine up to about 32 hours after intake of a single common therapeutic dose. The target analytes were found to be the parent compound DRO (earlier phase of excretion) and the hydroxylated metabolite para-hydroxy-DRO (later phase of excretion). Both allowed unambiguous detection of an intake of DRO and also differentiation from other phenylpiperazine derivatives. PMID:15257075

Staack, Roland F; Theobald, Denis S; Maurer, Hans H

2004-08-01

308

Rapid and selective determination of free chlorine in aqueous solution using electrophilic addition to styrene by gas chromatography/mass spectrometry.  

PubMed

We developed a rapid and selective method for determination of free chlorine in aqueous solution by gas chromatography/mass spectrometry for the first time. Free chlorine was converted to styrene chlorohydrin using electrophilic addition to styrene in sodium acetate buffer solution (pH 5). The chlorine derivative obtained was extracted with chloroform, and then analyzed by GC/MS. The calibration curve showed good linearity from 0.2-100 ?g/mL (as available chlorine). The detection limit was 0.1 ?g/mL, and the intra- and interday accuracy were measured at concentrations of 10, 50, and 75 ?g/mL to be -1.3 to 6.9% (intraday) and 3.8-8.0% (interday) as % Bias. The precision was between 1.4 and 4.5% as % RSD. These results indicate that this method is a superior technique for the identification of free chlorine. This method was successfully applied to quantification in commercial samples and in samples of a criminal case. PMID:23200361

Wakigawa, Kengo; Gohda, Akinaga; Fukushima, Sunao; Mori, Takeshi; Niidome, Takuro; Katayama, Yoshiki

2013-01-15

309

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

PubMed

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 (GCGC/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 GCGC 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

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

2014-10-17

310

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

PubMed

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 separation with ethyl acetate has been tested. This procedure enhances the sensitivity of the method by extracting the colouring compounds from the rest of the compounds present in the natural dye. Two possible derivatising reagents--HMDS and tetramethylammonium hydroxide (TMAH)--were compared in order to assess their effectiveness in the proposed method. Characteristic peaks from trimethylsilyl derivatives of alizarin, quinizarin, xanthopurpurin and purpurin were obtained for madder; peaks from safranal, isophorone and trimethylsilyl derivative of crocetin for saffron; peaks from 4-(4-hydroxy-3-methoxy)phenyl-3-buten-2-one and 4-(4-hydroxy-3-methoxy)phenyl-2-butanone, which are primary pyrolysis products of curcuma, and peaks from indole, 2-methylindole and 2,3-dihydroindol-2-one, which are primary pyrolysis products of indigo, among others, were obtained. The reported procedure leads to the unambiguous identification of the four studied dyes from solid samples formed by individual dyes. PMID:15782338

Casas-Cataln, Mara Jos; Domnech-Carb, Mara Teresa

2005-05-01

311

Solid-phase microextraction-gas chromatography-mass spectrometry for the analysis of selective serotonin reuptake inhibitors in environmental water.  

PubMed

The continuous contamination of surface waters by pharmaceuticals is of most environmental concern. Selective serotonin reuptake inhibitors (SSRIs) are drugs currently prescribed for the treatment of depressions and other psychiatric disorders and then, they are among the pharmaceuticals that can occur in environmental waters. Solid-phase microextraction (SPME) coupled to gas chromatography-mass spectrometry has been applied to the extraction of five SSRIs--venlafaxine, fluvoxamine, fluoxetine, citalopram and sertraline--from water samples. Some of the analytes were not efficiently extracted as underivatized compounds and so, an in situ acetylation step was introduced in the sample preparation procedure. Different parameters affecting extraction efficiency such as extraction mode, fiber coating and temperature were studied. A mixed-level fractional factorial design was also performed to simultaneously study the influence of other five experimental factors. Finally, a method based on direct SPME at 100 degrees C using polydimethylsiloxane-divinylbenzene fibers is proposed. The performance of the method was evaluated, showing good linearity and precision. The detection limits were in the sub-ng/mL level. Practical applicability was demonstrated through the analysis of real samples. Recoveries obtained for river water and wastewater samples were satisfactory in all cases. An important aspect of the proposed method is that no matrix effects were observed. Two of the target compounds, venlafaxine and citalopram, were detected and quantified in a sewage water sample. PMID:15387194

Lamas, J Pablo; Salgado-Petinal, Carmen; Garca-Jares, Carmen; Llompart, Mara; Cela, Rafael; Gmez, Mariano

2004-08-13

312

Determination of cyclic and linear siloxanes in wastewater samples by ultrasound-assisted dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry.  

PubMed

A fast, simple and environmentally friendly ultrasound-assisted dispersive liquid-liquid microextraction (USA-DLLME) procedure has been developed to preconcentrate eight cyclic and linear siloxanes from wastewater samples prior to quantification by gas chromatography-mass spectrometry (GC-MS). A two-stage multivariate optimization approach has been developed employing a Plackett-Burman design for screening and selecting the significant factors involved in the USA-DLLME procedure, which was later optimized by means of a circumscribed central composite design. The optimum conditions were: extractant solvent volume, 13 L; solvent type, chlorobenzene; sample volume, 13 mL; centrifugation speed, 2300 rpm; centrifugation time, 5 min; and sonication time, 2 min. Under the optimized experimental conditions the method gave levels of repeatability with coefficients of variation between 10 and 24% (n=7). Limits of detection were between 0.002 and 1.4 g L(-1). Calculated calibration curves gave high levels of linearity with correlation coefficient values between 0.991 and 0.9997. Finally, the proposed method was applied for the analysis of wastewater samples. Relative recovery values ranged between 71 and 116% showing that the matrix had a negligible effect upon extraction. To our knowledge, this is the first time that combines LLME and GC-MS for the analysis of methylsiloxanes in wastewater samples. PMID:24468359

Cortada, Carol; dos Reis, Luciana Costa; Vidal, Lorena; Llorca, Julio; Canals, Antonio

2014-03-01

313

Analysis of alkyl and 2-6-ringed polycyclic aromatic hydrocarbons by isotope dilution gas chromatography/mass spectrometry. Quality assurance and determination in Spanish river sediments.  

PubMed

An accurate, precise and sensitive method is described for the analysis of 29 polycyclic aromatic hydrocarbons (PAHs), including 19 2-6-ringed PAHs and 10 alkyl-PAHs. The method is based on an isotope dilution technique using gas chromatography/mass spectrometry (GC/MS) and available labeled PAHs as internal standards. Quality parameters were calculated with satisfactory results and 36 Spanish river sediments were analysed. Results were evaluated regarding to the sediment quality guidelines (SQGs) based on the effects range-low (ERL) and the effects range-median (ERM) values. Most analysed sediments showed a good quality, since only 7 of them exceeded ERL values, including one sample surpassing ERM values. PAH profiles were studied in order to identify PAH sources as mainly petrogenic or pyrogenic. Most samples showed petrogenic-type fingerprints, although 6 of the 11 sediments with the highest PAH concentrations (> 1000 ng/g) were classified as pyrogenic, including 4 of the 7 samples exceeding ERL values. Quality assurance was carried out by the triplicate analysis of one preanalysed river sediment without PAHs subsequently spiked at a medium (500 ng/g) and a low concentration level (10 ng/g) of each analyte. Main quality requirements for methods based on isotope dilution were accomplished. Method accuracy was 80-120% for most PAHs, method precision was <15% for all the analysed compounds and method detection limits (MDLs) were 1-3 ng/g. PMID:16513126

Planas, Carles; Puig, Alejandra; Rivera, Josep; Caixach, Josep

2006-04-28

314

Quantitative gas chromatography-mass spectrometry isomer-specific measurement of hydroxy fatty acids in biological samples and food as a marker of lipid peroxidation.  

PubMed

We have developed a capillary gas chromatography-mass spectrometry method for the quantitative analysis of individual positional isomers of monohydroxy fatty acids derived from linoleic, arachidonic, eicosapentaenoic, or docosahexaenoic acid. Peroxidation of a particular polyunsaturated fatty acid results already in a complex mixture of positional isomers of hydroperoxy and hydroxy fatty acids. Catalytic hydrogenation of lipid extracts produces stable saturated hydroxy lipids from the complex mixtures typical of oxidized biological samples, simultaneously simplifying the analytical problem and eliminating oxidation artifacts. After saponification and methylation, monohydroxy fatty acid methyl esters are purified by solid-phase extraction and partially resolved using a CP Sil 19 column following on-column derivatization of the hydroxy groups with tetramethylammonium hydroxide. The resulting methoxy fatty acid methyl esters are subjected to electron impact mass spectroscopy. Two characteristic ions are produced for each positional isomer. Quantitative measurements were achieved by using odd chain C17 and C19 monohydroxy fatty acids as internal standards. The limit of detection of individual hydroxy fatty acid isomers is dependent on the total number of ions monitored. Monitoring 11 pairs of ions simultaneously gives limits of detection of 10 ng. Sensitivity is much higher by monitoring fewer ions and as little as 0.2 ng of a single isomer can be detected. The method has been applied for the quantitative analysis of hydroxy (plus hydroperoxy) fatty acids in plasma, adipose tissue, oils, and foods. To date over 1000 samples have been analyzed using the method described in this paper. PMID:9177726

Wilson, R; Smith, R; Wilson, P; Shepherd, M J; Riemersma, R A

1997-05-15

315

Comparative Analysis of the Volatile Components of Agrimonia eupatoria from Leaves and Roots by Gas Chromatography-Mass Spectrometry and Multivariate Curve Resolution.  

PubMed

Gas chromatography-mass spectrometry and multivariate curve resolution were applied to the differential analysis of the volatile components in Agrimonia eupatoria specimens from different plant parts. After extracted with water distillation method, the volatile components in Agrimonia eupatoria from leaves and roots were detected by GC-MS. Then the qualitative and quantitative analysis of the volatile components in the main root of Agrimonia eupatoria was completed with the help of subwindow factor analysis resolving two-dimensional original data into mass spectra and chromatograms. 68 of 87 separated constituents in the total ion chromatogram of the volatile components were identified and quantified, accounting for about 87.03% of the total content. Then, the common peaks in leaf were extracted with orthogonal projection resolution method. Among the components determined, there were 52 components coexisting in the studied samples although the relative content of each component showed difference to some extent. The results showed a fair consistency in their GC-MS fingerprint. It was the first time to apply orthogonal projection method to compare different plant parts of Agrimonia eupatoria, and it reduced the burden of qualitative analysis as well as the subjectivity. The obtained results proved the combined approach powerful for the analysis of complex Agrimonia eupatoria samples. The developed method can be used to further study and quality control of Agrimonia eupatoria. PMID:24286016

Feng, Xiao-Liang; He, Yun-Biao; Liang, Yi-Zeng; Wang, Yu-Lin; Huang, Lan-Fang; Xie, Jian-Wei

2013-01-01

316

Stir bar sorptive extraction coupled to gas chromatography-mass spectrometry for the determination of bisphenols in canned beverages and filling liquids of canned vegetables.  

PubMed

This paper describes a method for the simultaneous determination of bisphenol A (BPA), bisphenol F (BPF), bisphenol Z (BPZ) and biphenol (BP), using stir bar sorptive extraction (SBSE) in combination with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). Several parameters affecting both extraction and thermal desorption of the SBSE stages were carefully optimized by multivariate designs. SBSE was performed with two derivatization procedures, in situ acetylation and in tube silylation, and the results were compared with those obtained when the analytes were not derivatized. The proposed method, determining the analytes as acyl derivatives, was applied to analyze commercially canned beverages, as well as the filling liquids of canned vegetables, providing detection limits of between 4.7 and 12.5 ng L?, depending on the compound. The intraday and interday precisions were lower than 6% in terms of relative standard deviation. Recovery studies at two concentration levels, 0.1 and 1 ?g L?, were performed providing recoveries in the 86-122% range. The samples analyzed contained higher concentrations of BPA than of the other analytes. PMID:22682950

Cacho, J I; Campillo, N; Vias, P; Hernndez-Crdoba, M

2012-07-20

317

Analysis of salicylate and benzophenone-type UV filters in soils and sediments by simultaneous extraction cleanup and gas chromatography-mass spectrometry.  

PubMed

An analytical method for the determination of UV filters in soil and sediment has been developed and validated considering benzophenones (BP) and salicylates as target analytes. Soil and sediment samples were extracted with ethyl acetate-methanol (90:10, v/v) assisted with sonication, performing a simultaneous clean-up step. Quantification of these compounds was carried out by gas chromatography-mass spectrometry (GC-MS) after derivatization of the extracts with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA). Recoveries from spiked soil samples ranged from 89.8% to 104.4% and they were between 88.4% and 105.3% for spiked sediment samples. The effect of the residence time and soil moisture content on the recovery of these compounds was also studied. The precision, expressed as relative standard deviation, was in all cases below 6.1% and the limits of detection (S/N=3) varied from 0.07 to 0.10 ng g(-1) and from 0.11 to 0.28 ng g(-1) for soils and sediments, respectively. The validated method was applied to the analysis of five benzophenone and two salicylate UV filters in soil and sediment samples collected in different areas of Spain. PMID:21636087

Snchez-Brunete, Consuelo; Miguel, Ester; Albero, Beatriz; Tadeo, Jos L

2011-07-15

318

Detection of Urinary Metabolomics before and after Pringle Maneuver-Induced Liver Ischemia and Reperfusion Injury in Rats Using Gas Chromatography-Mass Spectrometry  

PubMed Central

Background. Metabolomics studies can quantitatively detect the dynamic metabolic response of living systems. Objective. To detect urinary metabolomics after hepatic ischemia/reperfusion (I/R) injury induced by the Pringle maneuver using gas chromatography-mass spectrometry (GC-MS). Methods. Male Sprague-Dawley rats (N = 80) were randomly divided into 4 groups (n = 20/group): sham operation, day 1, day 3, and day 5. Rats in the day 1, day 3, and day 5 groups underwent the Pringle maneuver. Serum alanine transaminase (ALT) and total bilirubin (TBIL) were measured, and hematoxylin and eosin (HE) staining of the liver tissue was performed. GC-MS was used to detect urinary metabolomics. Results. Compared with the sham group, the serum ALT and TBIL levels at day 1 were significantly elevated (P < 0.01) and then decreased and reached close to normal levels at day 5. GC-MS detected 7 metabolites which had similar changes as those of liver tissue revealed by histological examination. Significant differences in lactic acid, pyruvic acid, alanine, serine, and glycerol-3-phosphate were found among the groups (P < 0.001). Principle component analysis showed that 7 metabolites distinguished the day 1 and day 3 groups from the sham group. Conclusions. Noninvasive urinary metabolomic analysis is a potential means for the early detection and diagnosis of hepatic I/R injury. PMID:24191128

Chen, Liyan; Luo, Zhenchao; Fu, Wenguang; Liao, Xinxin; Cui, Zhonglin

2013-01-01

319

Development of microwave-assisted derivatization followed by gas chromatography/mass spectrometry for fast determination of amino acids in neonatal blood samples.  

PubMed

Analysis of amino acids in blood samples is an important tool for the diagnosis of neonatal amino acid metabolism disorders. In the work, a novel, rapid and sensitive method was developed for the determination of amino acids in neonatal blood samples, which was based on microwave-assisted silylation followed by gas chromatography/mass spectrometry (GC/MS). The amino acids were derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) under microwave irradiation. The controlled reaction was carried out employing BSTFA under conventional heating at 120 degrees C for 30 min. Experimental results show that microwave irradiation can accelerate the derivatization reaction of amino acids with BSFTA, and much shorten analysis time. The method validations (linear range, detection limit, precision and recovery) were studied. Finally, the method was tested by determination of amino acids in neonatal blood by the measurement of their trimethylsilyl derivatives by GC/MS in electron impact (EI) mode. Two biomarkers of L-phenylalanine and L-tyrosine in phenylketonuria (PKU)-positive blood and control blood were quantitatively analyzed by the proposed method. The results demonstrated that microwave-assisted silylation followed by GC/MS is a rapid, simple and sensitive method for amino acid analysis and is also a potential tool for fast screening of neonatal aminoacidurias. PMID:16015674

Deng, Chunhui; Yin, Xinying; Zhang, Lijuan; Zhang, Xiangmin

2005-01-01

320

Quantitative determination of eight components in rhizome (Jianghuang) and tuberous root (Yujin) of Curcuma longa using pressurized liquid extraction and gas chromatography-mass spectrometry.  

PubMed

Curcuma longa (Zingiberaceae) is a native plant of southern Asia and is cultivated extensively throughout the warmer parts of the world. Jianghuang and Yujin are rhizome and tuberous root of C. longa, respectively, which were traditionally used as two Chinese medicines. In this paper, pressurized liquid extraction (PLE) and gas chromatography-mass spectrometry (GC-MS) were developed for quantitative determination/estimation of eight characteristic compounds including beta-caryophyllene, ar-curcumene, zingiberene, beta-bisabolene, beta-sesquiphellandrenendrene, ar-turmerone, alpha-turmerone and beta-turmerone in Jianghuang and Yujin. A HP-5MS capillary column (30 m x 0.25 mm i.d.) coated with 0.25 microm film 5% phenyl methyl siloxane was used for separation and selected ion monitoring (SIM) method was used for quantitation. Hierarchical cluster analysis based on characteristics of eight identified peaks in GC-MS profiles showed that 10 samples were divided into two main clusters, Jianghuang and Yujin, respectively. Four components such as ar-curcumene, ar-turmerone, alpha-turmerone and beta-turmerone were optimized as markers for quality control of rhizome (Jianghuang) and tuberous root (Yujin), which are two traditional Chinese medicines, from Curcuma longa. PMID:16930909

Qin, N Y; Yang, F Q; Wang, Y T; Li, S P

2007-01-17

321

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

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

Sereshti, Hassan; Heidari, Reza; Samadi, Soheila

2014-01-15

322

Comparison of the sensitivity of different aroma extraction techniques in combination with gas chromatography-mass spectrometry to detect minor aroma compounds in wine.  

PubMed

MicroVinification platforms are used for screening purposes to study aroma development in wine. These high-throughput methodologies require flavor analysis techniques that allow fast detection of a high number of aroma compounds which often appear in very low concentrations (?g/l). In this work, a selection of aroma extraction techniques in combination with gas chromatography-mass spectrometry (GC-MS) were evaluated to detect minor wine aroma compounds in low sample volume. The techniques evaluated were headspace (HS), headspace solid-phase dynamic extraction (HS-SPDE), headspace solid-phase microextraction (HS-SPME), direct immersion solid-phase microextraction (DI-SPME), stir bar sorptive extraction (SBSE) and monolithic material sorptive extraction (MMSE). DI-SPME showed the highest sensitivity as expressed by detection of the highest percentage of total aroma compounds at concentrations around 0.1 ?g/l. SBSE and MMSE followed DI-SPME in terms of sensitivity. HS-SPME was less sensitive but considered sensitive enough for detection of most of the volatile compounds present in highly aromatic wines. Matrix effect was shown to strongly affect aroma extraction and therefore the sensitivity of the different extraction methods. PMID:23245586

Gamero, Amparo; Wesselink, Wilma; de Jong, Catrienus

2013-01-11

323

Concurrent quantification of light and heavy sulphur volatiles in wine by headspace solid-phase microextraction coupled with gas chromatography/mass spectrometry.  

PubMed

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

Fedrizzi, Bruno; Magno, Franco; Moser, Sergio; Nicolini, Giorgio; Versini, Giuseppe

2007-01-01

324

Multi-residue off-flavour profiling in wine using stir bar sorptive extraction-thermal desorption-gas chromatography-mass spectrometry.  

PubMed

A multi-residue method (MRM) for the detection and quantification of eight compounds responsible for off-flavours in wine using stir bar sorptive extraction (SBSE) followed by thermal desorption (TD) and gas chromatography-mass spectrometry (GC-MS) analysis is presented. The extraction and desorption conditions were optimised in order to get the best compromise for the simultaneous analysis of the eight target solutes, belonging to different chemical classes. The analytical conditions enable the quantification of the solutes below their respective organoleptic perception thresholds in wine. The method displayed good linearity over the concentration ranges explored in wine as well as excellent repeatability (RSD below 6%) and good reproducibility (RSD below 24%). The developed methodology was applied to the analysis of several wines and showed good agreement with the results collected with headspace solid-phase microextraction (HS-SPME) or liquid-liquid extraction (LLE) followed by GC-MS or electron capture detection (ECD). Good correlation was also found between the analytical and sensory results. PMID:19233369

Franc, Cline; David, Frank; de Revel, Gilles

2009-04-10

325

Determination of phthalates in wine by headspace solid-phase microextraction followed by gas chromatography-mass spectrometry: fibre comparison and selection.  

PubMed

This paper describes the development of a headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) method for determining phthalates in wine. The HS-SPME conditions were thoroughly studied: first, the performance of six fibres at three temperature values and two sample volumes was surveyed by means of a 6 x 3 x 2 multi-factor categorical experimental design. From this study, three fibres - carbowax-divinylbenzene (CW-DVB), polyacrylate (PA) and polydimethylsiloxane-divinylbenzene (PDMS-DVB) - were selected. Then, temperature, sample volume and sodium chloride concentration were optimised using a central composite design and the overall desirability function for each fibre. The optimal values were 70 degrees C, a NaCl concentration of 2.6, 3.6 and 5.5M for PA, CW-DVB and PDMS-DVB fibres, respectively, and sample volumes of 4.0, 3.5 and 3.0 mL. Next, the performance characteristics of the three fibres were obtained and compared. PDMS-DVB fibre showed the best repeatability values followed by CW-DVB. PA fibre was not suitable for diethylhexylphthalate extraction and showed poor repeatability for the heavier phthalates, and was therefore discarded. Finally, the performance of CW-DVB and PDMS-DVB fibres was checked for red, white and ros wines. PMID:17644103

Carrillo, J D; Salazar, C; Moreta, C; Tena, M T

2007-09-14

326

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

PubMed

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

Wang, Perry G; Krynitsky, Alexander J

2011-06-15

327

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

PubMed

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 0.05pgmL(-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

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

2015-02-13

328

Determination of atrazine and its major degradation products in soil pore water by solid-phase extraction, chemical derivatization, and gas chromatography/mass spectrometry  

USGS Publications Warehouse

This report describes a method for the determination of atrazine, desethylatrazine, deisopropylatrazine, didealkylatrazine, and hydroxyatrazine from soil pore waters by use of solid-phase extractionfollowed by chemical derivatization and gas chromatography/mass spectrometry. The analytes are isolated from the pore-water matrix byextraction onto a graphitized carbon-black cartridge. The cartridge is dried under vacuum, and adsorbed analytes are removed by elution with ethyl acetate followed by dichloromethane/methanol (7:3, volume/volume). Water is removed from the ethyl acetate fraction on an anhydrous sodium sulfate column. The combined fractions are solvent exchanged into acetonitrile, evaporated by use of a nitrogen stream, and derivatized by use of N- methyl-N-(tert-butyldimethylsilyl)- trifluoroacetamide. The derivatized extracts are analyzed by capillary-column gaschromatography/electron-impact mass spectrometry in the scan mode. Estimated method detection limits range from 0.03 to 0.07 micrograms per liter. The mean recoveries of all analytes and surrogates determined at 0.74 to 0.82 micrograms per liter in reagent water in soil pore water were 94 percent and 98 percent, respectively. The mean recoveries of all analytes and surrogates determined at 7.4 to 8.2 micrograms per liter in reagent water and in soil pore water were 96 percent and 97 percent,respectively. Recoveries were 90 percent or higher, regardless of analyte concentration or matrix composition, for all compounds excepthydroxyatrazine, whose recoveries were slightly lower (77 percent) at the low concentration.

Carter, D.S.

1996-01-01

329

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

PubMed

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

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

2009-12-01

330

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

PubMed

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

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

2014-11-01

331

Quantitation of total homocysteine in human plasma by derivatization to its N(O,S)-propoxycarbonyl propyl ester and gas chromatography-mass spectrometry analysis.  

PubMed

Much evidence supports the hypothesis that mild or moderate hyperhomocysteinaemia represents an important and independent risk factor for occlusive vascular diseases. Therefore, the accurate and reliable determination of total plasma homocysteine has gained major importance for risk assessment. Furthermore, it can help in the detection of folate and vitamin B12 deficiency. This has prompted us to develop a sensitive gas chromatography-mass spectrometry (GC-MS) method in order to quantify total homocysteine in human plasma. Prior to chromatography, reduced homocysteine was released from disulfide bonds by incubation with excess dithiothreitol and converted into its N(O,S)-propoxycarbonyl propyl ester by derivatization with n-propyl chloroformate. Aminoethylcysteine served as internal standard. The method proved to be highly linear over the entire concentration range examined (corresponding to 0-266 microM homocysteine) and showed intra-assay and inter-assay variation (relative standard deviations) of approximately 5 and 5-10%, respectively. External quality control by comparison with duplicate analysis performed on a HPLC-based system revealed satisfactory correlation. The newly developed GC-MS based method provides simple, reliable and fast quantification of total homocysteine and requires only inexpensive chemicals, which are easy to obtain. PMID:9291598

Sass, J O; Endres, W

1997-08-01

332

Development and validation of a gas chromatography/mass spectrometry procedure for confirmation of para-toluenesulfonamide in edible fish fillet tissue  

USGS Publications Warehouse

Chloramine-T is a disinfectant being developed as a treatment for bacterial gill disease in cultured fish. As part of the drug approval process, a method is required for the confirmation of chloramine-T residues in edible fish tissue. The marker residue that will be used to determine the depletion of chloramine-T residues from the edible tissue of treated fish is para-toluenesulfonamide (p-TSA), a metabolite of chloramine-T. The development and validation of a procedure for the confirmation of p-TSA is described. Homogenized fish tissue is dried by mixing with anhydrous sodium sulfate, and the mixture is extracted with methylene chloride. The extract is passed through a silica gel solid-phase extraction column, from which p-TSA is subsequently eluted with acetonitrile. The acetonitrile extract is evaporated, and the oily residue is dissolved in hexane. The hexane solution is shaken with fresh acetonitrile. The acetonitrile solution is evaporated and the residue is redissolved in dilute potassium hydroxide solution. The aqueous solution is extracted with methylene chloride to further remove more of the fat co-extractive. The aqueous solution is reacted with pentafluorobenzyl bromide in presence of tetrabutylammonium hydrogensulfate. The resulting di-(pentafluorobenzyl) derivative of p-TSA is analyzed by gas chromatography/mass spectrometry. This method permits the confirmation of p-TSA in edible fish tissue at 20 ppb.

Idowu, O.R.; Kijak, P.J.; Meinertz, J.R.; Schmidt, L.J.

2004-01-01

333

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

PubMed

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 g/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

Heydari, Rouhollah; Azizi, Saber

2014-11-14

334

Determination of furan in jarred baby food purchased from the Spanish market by headspace gas chromatography-mass spectrometry (HS-GC-MS).  

PubMed

The aim of this paper is to offer a method based on headspace gas chromatography-mass (HS-GC-MS) spectrometry technique in-house validated and use to estimate furan concentrations in jarred baby-food samples purchased from the Spanish market. The validation was performed according to ISO 17025 and European Food Safety Authority (EFSA) requirements and the results obtained (limit of detection (LOD) = 0.05 microg kg(-1); limit of quantification (LOQ) = 4 microg kg(-1), lowest validated level; relative standard deviation (RSD) = 3.1-10.5%; recoveries = 85.4-101.5%) confirm that this method is fit for the routine analysis of furan in jarred baby food control. Furan was analysed in 39 different baby-food samples and the mean levels varied between 64.6 microg kg(-1) (rice and chicken samples) and less than or equal to the LOQ (fruit-based samples). The mean concentrations found for the different matrices were 5.0, 37.8, 25.2, 33.8 and 30.5 microg kg(-1) for fruit, vegetables, meat/vegetables, fish/vegetables and dairy-containing baby foods, respectively. According to the statistical analyses, fruit-based baby-food samples had significantly lower concentrations of furan. Mean values for the other matrices were at least five times higher, and this is in accordance with the levels reported in other studies. PMID:20582781

Ruiz, E; Santillana, M I; Nieto, M T; Cirugeda, M E; Sanchez, J J

2010-09-01

335

Single-drop microextraction with in-microvial derivatization for the determination of haloacetic acids in water sample by gas chromatography-mass spectrometry.  

PubMed

A new approach using single-drop microextraction (SDME) and gas chromatography-mass spectrometry for the determination of six haloacetic acids (HAAs) in water samples was presented. n-Octanol was used as extractant and derivatization reagent. HAAs were derivatized both simultaneously during the extraction in the solvent microdrop, and after extraction, inside a glass microvial (1.1mm I.D.). Trifluoroacetic anhydride (TFAA) was used as the reaction catalyst. The influence of catalyst amount, derivatization time and temperature on the yield of the in-microvial derivatization was investigated. Derivatization reaction was performed using 1.2microL of TFAA at 100 degrees C for 20min. Extraction was performed using 1.8microL of n-octanol containing TFAA (10%, v/v). Experimental parameters, such as, exposure time, sample pH and extraction temperature were controlled and optimized. Analytical parameters such as linearity, precision and limit of detection were also evaluated. The proposed method was proved to be a suitable analytical procedure for HAAs in water with limits of detection 0.1-1.2microg/L. The relative recoveries range from 82.5 to 97.6% for all the target analytes. Precision values were from 5.1 to 8.5% (as intra-day relative standard deviation, RSD) and 8.8-12.3% (as inter-day RSD). PMID:19135207

Saraji, Mohammad; Bidgoli, Ali Akbar Hajialiakbari

2009-02-13

336

Development of a method for analysis of Iranian damask rose oil: combination of gas chromatography-mass spectrometry with Chemometric techniques.  

PubMed

Gas chromatography-mass spectrometry (GC-MS) combined with Chemometric resolution techniques were proposed as a method for the analysis of volatile components of Iranian damask rose oil. The essential oil of damask rose was extracted using hydrodistillation method and analyzed with GC-MS in optimized conditions. A total of 70 components were identified using similarity searches between mass spectra and MS database. This number was extended to 95 components with concentrations higher than 0.01% accounting for 94.75% of the total relative content using Chemometric techniques. For the first time in this work, an approach based upon subspace comparison is used for determination of the chemical rank of GC-MS data. The peak clusters were resolved using heuristic evolving latent projection (HELP) and multivariate curve resolution-alternating least square (MCR-ALS) by applying proper constraints, and the combination of both methods for some cases. It is concluded that a thorough analysis of the complex mixtures such as Iranian damask rose requires sophisticated GC-MS coupled with the Chemometric techniques. PMID:18611452

Jalali-Heravi, Mehdi; Parastar, Hadi; Sereshti, Hassan

2008-08-01

337

Comparative Analysis of the Volatile Components of Agrimonia eupatoria from Leaves and Roots by Gas Chromatography-Mass Spectrometry and Multivariate Curve Resolution  

PubMed Central

Gas chromatography-mass spectrometry and multivariate curve resolution were applied to the differential analysis of the volatile components in Agrimonia eupatoria specimens from different plant parts. After extracted with water distillation method, the volatile components in Agrimonia eupatoria from leaves and roots were detected by GC-MS. Then the qualitative and quantitative analysis of the volatile components in the main root of Agrimonia eupatoria was completed with the help of subwindow factor analysis resolving two-dimensional original data into mass spectra and chromatograms. 68 of 87 separated constituents in the total ion chromatogram of the volatile components were identified and quantified, accounting for about 87.03% of the total content. Then, the common peaks in leaf were extracted with orthogonal projection resolution method. Among the components determined, there were 52 components coexisting in the studied samples although the relative content of each component showed difference to some extent. The results showed a fair consistency in their GC-MS fingerprint. It was the first time to apply orthogonal projection method to compare different plant parts of Agrimonia eupatoria, and it reduced the burden of qualitative analysis as well as the subjectivity. The obtained results proved the combined approach powerful for the analysis of complex Agrimonia eupatoria samples. The developed method can be used to further study and quality control of Agrimonia eupatoria. PMID:24286016

Feng, Xiao-Liang; He, Yun-biao; Liang, Yi-Zeng; Wang, Yu-Lin; Huang, Lan-Fang; Xie, Jian-Wei

2013-01-01

338

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

PubMed

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 1.6-183.5ng/L, and satisfied recoveries (67.3-113.7%). PMID:25660867

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

2015-06-15

339

Rapid determination of acetone in human blood by derivatization with pentafluorobenzyl hydroxylamine followed by headspace liquid-phase microextraction and gas chromatography/mass spectrometry.  

PubMed

In the current work, a simple, rapid, accurate and inexpensive method was developed for the determination of acetone in human blood. The proposed method is based on derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA), followed by headspace liquid-phase microextraction (HS-LPME) and gas chromatography/mass spectrometry (GC/MS). In the present method, acetone in blood samples was derivatized with PFBHA and acetone oxime formed in several seconds. The formed oxime was enriched by HS-LPME using the organic solvent film (OSF) formed in a microsyringe barrel as extraction interface. Finally, the enriched oxime was analyzed by GC/MS in electron ionization (EI) mode. HS-LPME parameters including solvent, syringe plunger withdrawal rate, sampling volume, and extraction cycle were optimized and the method reproducibility, linearity, recovery and detection limit were studied. The proposed method was applied to determination of acetone in diabetes blood and normal blood. It has been shown that derivatization with HS-LPME and GC/MS is an alternative method for determination of the diabetes biomarker, acetone, in blood samples. PMID:15700238

Deng, Chunhui; Li, Ning; Wang, Xiaochuan; Zhang, Xiangmin; Zeng, Jia

2005-01-01

340

Determination of dimethyl sulfoxide and dimethyl sulfone in urine by gas chromatography-mass spectrometry after preparation using 2,2-dimethoxypropane.  

PubMed

A method for routinely determination of dimethyl sulfoxide (DMSO) and dimethyl sulfone (DMSO(2)) in human urine was developed using gas chromatography-mass spectrometry. The urine sample was treated with 2,2-dimethoxypropane (DMP) and hydrochloric acid for efficient removal of water, which causes degradation of the vacuum level in mass spectrometer and shortens the life-time of the column. Experimental DMP reaction parameters, such as hydrochloric acid concentration, DMP-urine ratio, reaction temperature and reaction time, were optimized for urine. Hexadeuterated DMSO was used as an internal standard. The recoveries of DMSO and DMSO(2) from urine were 97-104 and 98-116%, respectively. The calibration curves showed linearity in the range of 0.15-54.45 mg/L for DMSO and 0.19-50.10 mg/L for DMSO(2). The limits of detection of DMSO and DMSO(2) were 0.04 and 0.06 mg/L, respectively. The relative standard deviations of intra-day and inter-day were 0.2-3.4% for DMSO and 0.4-2.4% for DMSO(2). The proposed method may be useful for the biological monitoring of workers exposed to DMSO in their occupational environment. PMID:19688817

Takeuchi, Akito; Yamamoto, Shinobu; Narai, Rie; Nishida, Manami; Yashiki, Mikio; Sakui, Norihiro; Namera, Akira

2010-05-01

341

Response surface optimization for determination of volatile organic compounds in water samples by headspace-gas chromatography-mass spectrometry method.  

PubMed

The determination of benzene, toluene, p-xylene, tetrachloroethene, chlorobenzene, and dibromomethane in water by headspace analysis combined with gas chromatography-mass spectrometry (HS-GC-MS) has been investigated. An optimization strategy for the analysis of the six volatile organic compounds (VOCs) is presented with the experimental design and response surface methodology aid. Thermostatting time, temperature, and salt quantity were optimized by using a central composite design, and quadratic models relating peak areas to the three factors were built. The mathematical models were tested on a number of simulated data set and had a coefficient of R2>0.98. The factor effects were visualized as three-dimensional response surfaces and contour plots. The optimal conditions were achieved in 36.8 min, at 90 degrees C, and with 6 g of NaCl. The method showed a good agreement between the experimental data and predictive values throughout the studied parameter space, and was suitable for optimization studies of the VOCs in water by the HS-GC-MS method. PMID:19406010

Missaoui, Ins; Sayedi, Lotfi; Jamoussi, Bassem; Ben Hassine, Bchir

2009-04-01

342

Rapid differentiation of three Chamaecyparis species (Cupressaceae) grown in Taiwan using solid-phase microextraction-gas chromatography/mass spectrometry, cluster analysis, and principal component analysis.  

PubMed

Three Chamaecyparis species (C. formosensis, C. obtusa, and C. obtusa var. formosana) are difficult to distinguish by the naked eye. Therefore, from the chemotaxonomic point of view, it would be valuable to find a simple and rapid method to differentiate these three Chamaecyparis species. In this study, the chemical compositions of biogenic volatile organic compounds (BVOCs) from mature leaves were analyzed using solid-phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS). Then cluster analysis (CA) and principal component analysis (PCA) were conducted for the BVOC constituents to reveal the differences among these three species. Results from SPME-GC/MS showed that the compositions of BVOCs from the three species were distinctly different. Moreover, these species were clearly differentiated according to the results of CA and PCA. In conclusion, the findings of this study suggest that SPME-GC/MS coupled with CA and PCA is a feasible and rapid technique to differentiate Chamaecyparis species with similar morphological characteristics. PMID:21913656

Lin, Chun-Ya; Chen, Ying-Ju; Cheng, Sen-Sung; Chang, Shang-Tzen

2011-10-26

343

Study on the influence of pasture on volatile fraction of ewes' dairy products by solid-phase microextraction and gas chromatography-mass spectrometry.  

PubMed

The detection of markers of identification of the geographical origin of food is an attractive challenge and, as far as dairy products are concerned, this paper represents a contribution to this field. In this research the influence of feed on the volatile compound composition was investigated on milk, 2-mo-old cheese (Caciotta), and whey cheese (ricotta) obtained from the same flock of Sarda ewes, under standardized technological conditions. Three different types of pasture (mixture of Lolium perenne and Trifolium squarrosum; rough pasture; Avena sativa) were studied. Solid-phase microextraction combined with gas chromatography-mass spectrometry was used and principal component analysis was applied for statistical evaluation of the data set. The volatile composition was significantly affected by the type of pasture independently of the type of cheese and the ripening period. Moreover, a marker of rough pasture, tentatively identified as (E,E)-3,7,11-tri-methyl-2,4,10-dodecatriene, was detected only in milk and cheeses produced when the ewe flock grazed on that pasture. PMID:17235132

Povolo, M; Contarini, G; Mele, M; Secchiari, P

2007-02-01

344

Determination of atranol and chloroatranol in perfumes using simultaneous derivatization and dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry.  

PubMed

A new analytical method based on simultaneous derivatization and dispersive liquid-liquid microextraction (DLLME) followed by gas chromatography-mass spectrometry (GC-MS), for the determination of the allergenic compounds atranol and chloroatranol in perfumes, is presented. Derivatization of the target analytes by means of acetylation with anhydride acetic in carbonate buffer was carried out. Thereby volatility and detectability were increased for improved GC-MS sensitivity. In addition, extractability by DLLME was also enhanced due to a less polar character of the solutes. A liquid-liquid extraction was performed before DLLME to clean up the sample and to obtain an aqueous sample solution, free of the low polar matrix from the essential oils, as donor phase. Different parameters, such as the nature and volume of both the extraction and disperser solvents, the ionic strength of the aqueous donor phase or the effect of the derivatization reagent volume, were optimized. Under the selected conditions (injection of a mixture of 750?L of acetone as disperser solvent, 100?L of chloroform as extraction solvent and 100?L of anhydride acetic as derivatization reagent) the figures of merit of the proposed method were evaluated. Limits of detection in the low ngmL(-1) range were obtained. Matrix effect was observed in real perfume samples and thus, standard addition calibration is recommended. PMID:24793850

Lpez-Nogueroles, Marina; Chisvert, Alberto; Salvador, Amparo

2014-05-15

345

Simultaneous detection and quantification of select nitromusks, antimicrobial agent, and antihistamine in fish of grocery stores by gas chromatography-mass spectrometry.  

PubMed

Continually detected biologically persistent nitromusks; galaxolide (HHCB), tonalide (AHTN) and musk ketone (MK), antimicrobial triclosan (TCS), and antihistamine diphenhydramine (DPH) were examined for the first time in edible fillets originating from eight fish species grown in salt- and fresh-water. The sampled fish collected from local grocery stores were homogenized, extracted, pre-concentrated and analyzed by gas chromatography-mass spectrometry (GC-MS) using selected ion monitoring (SIM). The presence of the target compounds in fish extracts was confirmed based on similar mass spectral features and retention behavior with standards. Internal standard based calibration plots were used for quantification. The HHCB, AHTN, TCS and DPH were consistently observed with concentration of 0.163-0.892, 0.068-0.904, 0.189-1.182, and 0.942-7.472 ng g(-1), respectively. These values are at least 1-3 orders of magnitude lower than those obtained in environmental fish specimens. The MK was not detected in any fish. PMID:24377446

Foltz, James; Abdul Mottaleb, M; Meziani, Mohammed J; Rafiq Islam, M

2014-07-01

346

A simple and sensitive single-step method for gas chromatography-mass spectrometric determination of fipronil and its metabolites in sugarcane juice, jaggery and sugar.  

PubMed

A simple and sensitive single-step method for gas chromatography-mass spectrometric determination of fipronil and its metabolites viz., fipronil desulfinyl, fipronil sulphide and fipronil sulphone in sugarcane juice, jaggery and sugar has been developed. Acetonitrile was superior to ethyl acetate in terms of selectivity, though they were on par with each other in terms of recoveries. This method does not require any cleanup as the PSA-based cleanup was on par with no-cleanup treatment. Interestingly, the recoveries of fipronil and its metabolites decreased with increased amounts of C18 from 10 to 50mg/g of matrix. Matrix effects were insignificant and the limit of quantification was 0.005?g/g. The recoveries of fipronil and its metabolites varied between 87.5% and 108.5% with the RSD of 0.2-5.3% for all the three matrices studied. This method has also been validated by monitoring fipronil and its metabolites in the retail outlet samples of sugarcane juice, jaggery and sugar. PMID:24360469

Ramasubramanian, Thirumalaiandi; Paramasivam, Mariappan; Jayanthi, Ramabhadran; Chandrasekaran, Subramaniam

2014-05-01

347

Gas and liquid chromatography-mass spectrometry studies on the metabolism of the synthetic phenylacetylindole cannabimimetic JWH-250, the psychoactive component of smoking mixtures.  

PubMed

Prohibition of some synthetic cannabimimetics (e.g., JWH-018, JWH-073 and CP 47497) in a number of countries has led to a rise in new compounds in herbal mixtures that create marijuana-like psychotropic effects when smoked. The cannabimimetic JWH-250 (1-pentyl-3-(2-methoxyphenylacetyl)indole) was identified in May 2009 by the German Federal Criminal Police as an new ingredient in herbal smoking mixtures. The absence or low presence of the native compound in urine samples collected from persons who had consumed JWH-250 necessitates a detailed identification of their metabolites, which are excreted with urine and present in blood. Using gas and liquid chromatography-mass spectrometry (GC-MS and LC-MS/MS), we identified a series of metabolites in urine samples and serum sample from humans and urine samples from rats that were products of the following reactions: (a) mono- and dihydroxylation of aromatic and aliphatic residues of the parent compound, (b) trihydroxylation and dehydration of the N-alkyl chain, (c) N-dealkylation and (d) N-dealkylation and monohydroxylation. The prevailing urinary metabolites in humans were the monohydroxylated forms, while N-dealkylated and N-dealkyl monohydroxylated forms were found in rats. The detection of the mono- and dihydroxylated metabolites of JWH-250 in urine and serum samples by GC-MS and LC-MS/MS proved to be effective in determining consumption of this drug. PMID:21803006

Grigoryev, Andrej; Melnik, Aleksandra; Savchuk, Sergey; Simonov, Anton; Rozhanets, Vladimir

2011-09-01

348

Simultaneous determination of cotinine and trans-3-hydroxycotinine in urine by automated solid-phase extraction using gas chromatographymass spectrometry  

PubMed Central

A gas chromatographymass spectrometry method was developed and validated for the simultaneous automated solid-phase extraction and quantification of cotinine and trans-3-hydroxycotinine in human urine. Good linearity was observed over the concentration ranges studied (R2 > 0.99). The limit of quantification was 10 ng/mL for both analytes. The limits of detection were 0.06 ng/mL for cotinine (COT) and 0.02 ng/mL for trans-3-hydroxycotinine (OH-COT). Accuracy for COT ranged from 0.98 to 5.28% and the precision ranged from 1.24 to 8.78%. Accuracy for OH-COT ranged from ?2.66 to 3.72% and the precision ranged from 3.15 to 7.07%. Mean recoveries for cotinine and trans-3-hydroxycotinine ranged from 77.7 to 89.1%, and from 75.4 to 90.2%, respectively. This analytical method for the simultaneous measurement of cotinine and trans-3-hydroxycotinine in urine will be used to monitor tobacco smoking in pregnant women and will permit the usefulness of trans-3-hydroxycotinine as a specific biomarker of tobacco exposure to be determined. 2014 The Authors. Biomedical Chromatography published by John Wiley & Sons Ltd. PMID:24616054

Chiadmi, Fouad; Schlatter, Jol

2014-01-01

349

Development and validation of a gas chromatography/mass spectrometry procedure for confirmation of para-toluenesulfonamide in edible fish fillet tissue.  

PubMed

Chloramine-T is a disinfectant being developed as a treatment for bacterial gill disease in cultured fish. As part of the drug approval process, a method is required for the confirmation of chloramine-T residues in edible fish tissue. The marker residue that will be used to determine the depletion of chloramine-T residues from the edible tissue of treated fish is para-toluenesulfonamide (p-TSA), a metabolite of chloramine-T. The development and validation of a procedure for the confirmation of p-TSA is described. Homogenized fish tissue is dried by mixing with anhydrous sodium sulfate, and the mixture is extracted with methylene chloride. The extract is passed through a silica gel solid-phase extraction column, from which p-TSA is subsequently eluted with acetonitrile. The acetonitrile extract is evaporated, and the oily residue is dissolved in hexane. The hexane solution is shaken with fresh acetonitrile. The acetonitrile solution is evaporated and the residue is redissolved in dilute potassium hydroxide solution. The aqueous solution is extracted with methylene chloride to further remove more of the fat co-extractive. The aqueous solution is reacted with pentafluorobenzyl bromide in presence of tetrabutylammonium hydrogensulfate. The resulting di-(pentafluorobenzyl) derivative of p-TSA is analyzed by gas chromatography/mass spectrometry. This method permits the confirmation of p-TSA in edible fish tissue at 20 ppb. PMID:15493666

Idowu, Olutosin R; Kijak, Philip J; Meinertz, Jeffery R; Schmidt, Larry J

2004-01-01

350

Positron emission tomography-positive squalene-induced lipoid pneumonia confirmed by gas chromatography-mass spectrometry of bronchoalveolar lavage fluid.  

PubMed

Squalene is a type of oil obtained from shark liver. We describe a 76-year-old man diagnosed with chronic exogenous lipoid pneumonia due to squalene. A chest CT scan revealed pulmonary consolidation with ground-glass opacities in the right upper lobe. Positron emission tomography (PET) revealed significant uptake of 2-deoxy-2-F-fluoro-d-glucose (FDG) and 3'-deoxy-3'-F-fluorothymidine (FLT). Bronchoalveolar lavage (BAL) fluid contained many lipid-laden macrophages, and a transbronchial lung biopsy specimen showed clusters of foamy macrophages in alveolar spaces and granulomatous lesions. In addition, the presence of squalene in the BAL fluid was confirmed by gas chromatography-mass spectrometry, leading to a diagnosis of squalene-induced lipoid pneumonia. To the best of our knowledge, this is the first report of squalene-induced lipoid pneumonia in which squalene itself was successfully detected. This case also suggests the possibility that lipoid pneumonia shows significant uptake in FDG-PET and FLT-PET. PMID:18414072

Kanaji, Nobuhiro; Bandoh, Shuji; Takano, Koshiro; Kadota, Kyuichi; Haba, Reiji; Matsunaga, Toru; Kohno, Kohoji; Kushida, Yoshio; Yamamoto, Yuka; Ishida, Toshihiko

2008-04-01

351

Solid phase microextraction/gas chromatography/mass spectrometry integrated with chemometrics for detection of Salmonella typhimurium contamination in a packaged fresh vegetable.  

PubMed

A rapid method for detection of Salmonella typhimurium contamination in packaged alfalfa sprouts using solid phase microextraction/gas chromatography/mass spectrometry (SPME/GC/MS) integrated with chemometrics was investigated. Alfalfa sprouts were inoculated with S. typhimurium, packed into commercial LDPE bags and stored at 10+2 degrees C for 0, 1, 2 and 3 days. Uninoculated sprouts were used as control samples. A SPME device was used to collect the volatiles from the headspace above the samples and the volatiles were identified using GC/MS. Chemometric techniques including linear discriminant analysis (LDA) and artificial neural network (ANN) were used as data processing tools. Numbers of Salmonella were followed using a colony counting method. From LDA, it was able to differentiate control samples from sprouts contaminated with S. typhimurium. The potential to predict the number of contaminated S. typhimurium from the SPME/GC/MS data was investigated using multilayer perceptron (MLP) neural network with back propagation training. The MLP comprised an input layer, one hidden layer, and an output layer, with a hyperbolic tangent sigmoidal transfer function in the hidden layer and a linear transfer function in the output layer. The MLP neural network with a back propagation algorithm could predict number of S. typhimurium in unknown samples using the volatile fingerprints. Good prediction was found as measured by a regression coefficient (R(2)=0.99) between actual and predicted data. PMID:17386426

Siripatrawan, Ubonrat; Harte, Bruce R

2007-01-01

352

Solidification of floating organic drop liquid-phase microextraction cell fishing with gas chromatography-mass spectrometry for screening bioactive components from Amomum villosum Lour.  

PubMed

In this study, a novel solidification of floating organic drop liquid-phase microextraction cell fishing with gas chromatography-mass spectrometry (SFOD-LPME-CF-GC-MS) method was established and used to screen, isolate and analyze bioactive components from Amomum villosum Lour. extract. Through comparision of its effect on the models of normal cell and inflammatory cells, anti-inflammatory active components of essential oil from A. villosum Lour. were readily screened, and the components obtained are in agreement with related pharmacological articles. SFOD-LPME-CF-GC-MS was used to analyze the interaction of A. villosum Lour. extracts with normal and lipopolysaccharide-stimulated RAW264.7 macrophage cells. The effect of A. villosum Lour. essential oil extracts in the LPS-stimulated RAW264.7 model were also assessed in terms of cytotoxicity and nitric oxide production as an indication of bioactivity. Three potentially bioactive components were identified, demonstrating that SFOD-LPME-CF-GC-MS can be used successfully in the drug-screening process. This approach avoids the requirement for protein precipitation, but more importantly, generates a high concentration ratio, allowing analysis of trace components in traditional Chinese medicines. SFOD-LPME-CF-GC-MS is a simple, fast, effective and reliable method for the screening and analysis of bioactive components, and it can be extended to screen other bioactive components from TCMs. Copyright 2014 John Wiley & Sons, Ltd. PMID:25251881

Xue, Xue; Yang, Depo; Wang, Dongmei; Xu, Xinjun; Zhu, Longping; Zhao, Zhimin

2014-09-24

353

High concentration capacity sample preparation techniques to improve the informative potential of two-dimensional comprehensive gas chromatography-mass spectrometry: application to sensomics.  

PubMed

This study reports and critically discusses the results of a systematic investigation on the effectiveness of different and complementary sampling approaches, based on either sorption and adsorption, treated as a further dimension of a two-dimensional comprehensive gas chromatography-mass spectrometry analytical platform for sensomics. The focus is on the potentials of a group of high concentration capacity (HCC) sample preparation (Solid Phase Microextraction, SPME, Stir Bar Sorptive Extraction, SBSE and Headspace Sorptive Extraction, HSSE) and Dynamic Headspace (D-HS) techniques investigated to provide information useful for fingerprinting and profiling studies of food aroma. Volatiles and semi-volatiles contributing to define whole and nonfat dry milk aroma have been successfully characterized thanks to the combination of effective and selective sampling by HCC and D-HS techniques, high separation and detection power of GCGC-MS and suitable data elaboration (i.e., Comprehensive Template Matching Fingerprinting - CTMF). Out of the sample preparation techniques investigated, HSSE and SBSE have shown to be really effective for sensomics studies because of their high concentration factors, providing highly representative profiles as well as analyte recovery suitable for GC-Olfactometry even with high odor threshold (OT) markers or potent odorants in sub-trace amounts. PMID:24144305

Cordero, Chiara; Cagliero, Cecilia; Liberto, Erica; Nicolotti, Luca; Rubiolo, Patrizia; Sgorbini, Barbara; Bicchi, Carlo

2013-11-29

354

Gas chromatography-mass spectrometry determination of earthy-musty odorous compounds in waters by two phase hollow-fiber liquid-phase microextraction using polyvinylidene fluoride fibers.  

PubMed

A rapid and sensitive method for the determination of earthy-musty odorous compounds, 2-methylisoborneol, 2-isopropyl-3-methoxy pyrazine, 2,4,6-trichloroanisole, 2,3,6-trichloroanisole, and geosmin, in water samples has been developed. The method was based on coupling a new polyvinylidene fluoride (PVDF) hollow-fiber liquid-phase microextraction system with gas chromatography-mass spectrometry (GC-MS). The PVDF hollow fibers have high porosity and an enhanced solvent compatibility for extraction of the target analytes. Experimental conditions were optimized by investigating the type of extraction solvent, sample pH, sodium chloride concentration, stirring speed, extraction time, and GC-MS conditions. Under optimized conditions, the earthy-musty odorous compounds exhibited good linearity (R>0.995) in the concentration range of 6.2-250ng/L. The repeatability and reproducibility of the method were lower than 6.8% and 9.8%, respectively. The limit of detection and limit of quantification values were lower than 2.0 and 6.2ng/L, respectively. The analysis of different water samples such as tap, pond, rive and waste water indicated minimal matrix effects. Analyte recoveries for real samples spiked at different concentrations were between 84.4% and 117.5%. PMID:24456707

Yu, Shengbing; Xiao, Qin; Zhu, Binghui; Zhong, Xiuhua; Xu, Yinghua; Su, Guangning; Chen, Min

2014-02-14

355

Peak-bridges due to in-column analyte transformations as a new tool for establishing molecular connectivities by comprehensive two-dimensional gas chromatography-mass spectrometry.  

PubMed

Comprehensive two-dimensional gas chromatography-mass spectrometry (GCGC-MS) has been shown to permit for the unprecedented chromatographic resolution of volatile analytes encompassing various families of organic compounds. However, peak identification based on retention time, two-dimensional mapping, and mass spectrometric fragmentation only, is not a straightforward task yet. The possibility to establish molecular links between constituents is of crucial importance to understand the overall chemistry of any sample, especially in natural extracts where biogenetically related isomeric structures are often abundant. We here present a new way of using GCGC that allows searching for those molecular connectivities. Analytical investigations of essential oil constituents by means of GCGC-MS permitted to observe in real time the thermally-induced transformations of various sesquiterpenic derivatives. These transformations generated a series of well-defined two-dimensional peak bridges within the 2D-chromatograms connecting parent and daughter molecules, thus permitting to build a clear scheme of structural relationship between the different constituents. GCGC-MS appears here as a tool for investigating chromatographic phenomena and analyte transformations that could not be understood with conventional GC-MS only. PMID:25622519

Filippi, Jean-Jacques; Cocolo, Nicolas; Meierhenrich, Uwe J

2015-02-27

356

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

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

Juillet, Y; Dubois, C; Bintein, F; Dissard, J; Bosse, A

2014-08-01

357

Simultaneous determination of 2-naphthol and 1-hydroxypyrene in fish and shellfish contaminated with crude oil by gas chromatography-mass spectrometry.  

PubMed

This paper describes a gas chromatography-mass spectrometric method of l-hydroxypyrene (1-HOP) and 2-naphthol (2-NAP) in fish and shellfish. Alkali hydrolysis method in this study was chosen and optimized to the reaction condition for 90 min at 90C in a 2.0M KOH solution. For five independent determinations at 0.2 and 1.0 ?g/kg, the coefficient of variation was less than 5.1%. This method was used to assess the long-term influence of spilled crude oil on marine ecosystems and analyze fifty-two shellfish samples taken in the near of the accident region of the Hebei Spirit oil spill. 2-NAP and 1-HOP were detected in the mean concentration range of 0.09-12.42 and 0.03-0.06 ?g/kg, respectively. 2-NAP was detected in a high concentration range in shellfishes gathered in 2 months after the accident and it decreased rapidly to 6 months after that. The results showed that 2-NAP might be an important biomarker in biota contaminated with crude oil. PMID:23411178

Lim, Hyun-Hee; Shin, Ho-Sang

2013-06-01

358

Fiber-assisted emulsification microextraction coupled with gas chromatography-mass spectrometry for the determination of aromatic amines in aqueous samples.  

PubMed

A novel fiber-assisted emulsification microextraction (FAEME) method was developed for the determination of eight aromatic amines (AAs) in aqueous samples. In this method, the extraction solvent (100 ?L chlorobenzene) and the dispersive material (1.0mg kapok fiber fragments) were added successively into the aqueous sample (5.0 mL), and then the mixture was emulsified by ultrasound to form the cloudy solution. Phase separation was performed by centrifugation, and the sedimented phase was transferred to micro-inserts with a microsyringe for analysis. All variables involved in the extraction process were identified and optimized. By coupling the analysis with gas chromatography-mass spectrometry (GC-MS), excellent detection limits (0.01-0.2 ?g L(-1)), good precision (RSDs, 3.33-6.56%) and linear ranges (0.10-160 ?g L(-1) and 1.0-160 ?g L(-1)) were obtained. Compared with the traditional solvent-emulsification method, the extraction recoveries of the proposed method were much higher. Satisfactory recoveries were achieved when the method was used for the analysis of AAs in spiked real water samples. PMID:25152494

Feng, Wen; Jiang, Ruifen; Chen, Bo; Ouyang, Gangfeng

2014-09-26

359

Gas-Chromatography Mass-Spectrometry (GC-MS) Based Metabolite Profiling Reveals Mannitol as a Major Storage Carbohydrate in the Coccolithophorid Alga Emiliania huxleyi.  

PubMed

Algae are divergent organisms having a wide variety of evolutional histories. Although most of them share photosynthetic activity, their pathways of primary carbon metabolism are rather diverse among species. Here we developed a method for gas chromatography-mass spectroscopy (GC-MS) based metabolite profiling for the coccolithophorid alga Emiliania huxleyi, which is one of the most abundant microalgae in the ocean, in order to gain an overview of the pathway of primary metabolism within this alga. Following method optimization, twenty-six metabolites could be detected by this method. Whilst most proteogenic amino acids were detected, no peaks corresponding to malate and fumarate were found. The metabolite profile of E. huxleyi was, however, characterized by a prominent accumulation of mannitol reaching in excess of 14 nmol 106 cells-1. Similarly, the accumulation of the 13C label during short term H13CO3- feeding revealed a massive redistribution of label into mannitol as well as rapid but saturating label accumulation into glucose and several amino acids including aspartate, glycine and serine. These results provide support to previous work suggesting that this species adopts C3 photosynthesis and that mannitol functions as a carbon store in E. huxleyi. PMID:24957896

Obata, Toshihiro; Schoenefeld, Steffi; Krahnert, Ina; Bergmann, Susan; Scheffel, Andr; Fernie, Alisdair R

2013-01-01

360

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

PubMed

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

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

2013-12-01

361

Identification of resinous materials on 16th and 17th century reverse-glass objects by gas chromatography/mass spectrometry  

NASA Astrophysics Data System (ADS)

Objects of hinterglasmalerei, reverse-glass paintings, are painted on the back side of glass panels. Obviously, the paint layers are applied in reverse order, starting with the uppermost layer. The finished hinterglas painting is viewed through the glass, thus revealing an impressive gloss and depth of colour. The binding media of two precious objects of hinterglasmalerei from the 16th and 17th century have been identified as almost exclusively resinous. Identification was performed by a special optimised analysis procedure, which is discussed in this paper: solvent extracts are analysed by gas chromatography/mass spectrometry, both with and without derivatisation or hydrolysis. In an additional step, oxalic acid is added to the methanol extracts prior to injection. This attenuates the peaks of the non-acidic compounds, whereas the acids elute with good resolution. The non-acidic compounds are emphasised after injection of the underivatised extracts. This approach minimises compositional changes caused by the sample preparation and derivatisation steps. Chromatograms of aged samples with a very complex composition are simplified, which allows a more reliable and straightforward identification of significant markers for various materials. The binding media of the hinterglas objects were thus shown to consist of mixtures of different natural resins, larch turpentine, heat-treated Pinaceae resin or mastic. Typical compounds of dragon's blood, a natural red resin, were also detectable in red glazes by the applied analysis routine. Identification of the binding media provides valuable information that can be used in the development of an adequate conservation treatment.

Baumer, Ursula; Dietemann, Patrick; Koller, Johann

2009-07-01

362

Fast solid-phase extraction-gas chromatography-mass spectrometry procedure for oil fingerprinting. Application to the Prestige oil spill.  

PubMed

A rapid and simple fractionation procedure using solid-phase extraction (SPE) cartridges was developed for an accurate determination of aliphatic and polycyclic aromatic hydrocarbons in petroleum residues and further application in chemical fingerprinting of oil spills by gas chromatography-mass spectrometry (GC-MS). Among the adsorbents evaluated, SiO2/C3-CN exhibited the best selectivity, providing, by elution with n-hexane (4 ml) and n-hexane-CH2Cl2 (1:1) (5 ml), two well-resolved aliphatic and aromatic hydrocarbon fractions, with recoveries of 97 +/- 7.2 and 99.7 +/- 13.9%, respectively. The SPE fractionation procedure was compared with the conventional silica-alumina adsorption chromatography showing similar results but practical advantages in terms of reproducibility, analysis time, solvent reduction and cost. Moreover, is particularly suitable for routine analysis with a high sample throughput. The developed methodology was tested in the characterization of fuel-oil samples collected along the Spanish north-west coast, after the Prestige oil spill accident. PMID:14753680

Alzaga, Roberto; Montuori, Paolo; Ortiz, Laura; Bayona, Josep M; Albaigs, Joan

2004-01-30

363

Full automatic determination of chlorophenols in water using solid-phase microextraction/on-fiber derivatization and gas chromatography-mass spectrometry.  

PubMed

A fully automated combination of solid-phase microextraction and on-fiber derivatization coupled with gas chromatography-mass spectrometry was developed to determine 17 chlorophenols in aqueous samples. Optimal parameters for the automated process, such as fiber coating (polyacrylate), derivatization reagent (N,O-bis(trimethylsilyl) trifluoroacetamide), extraction time (60 min), derivatization time (5 min), incubation temperature (35C), sample pH (3), and ionic strength (300 g L(-1) of NaCl), as well as desorption time (5 min) and desorption temperature (270C) were established. The whole procedure took only 90 min and was performed automatically. The shortcomings of silylation derivatives, like incompleteness and instability, were overcome by using solid-phase microextraction on-fiber silylation in this study. The results from both pure water and river water samples showed that the method had a good linearity (r(2) = 0.9993-1.0000), ranging from 0.01 to 100 ?g L(-1). The related standard deviations were between 3.6 and 10.0%. The limits of detections and qualifications ranged from 0.03 to 3.11 ng L(-1) and 0.09 to 10.4 ng L(-1) for the CPs, respectively. The proposed method is superior to traditional solid phase extraction procedure. PMID:22589163

Wang, Xiaowei; Chen, Ruohong; Luan, Tiangang; Lin, Li; Zou, Shichun; Yang, Qingshu

2012-04-01

364

Simultaneous derivatization and extraction of nitrophenols in soil and rain samples using modified hollow-fiber liquid-phase microextraction followed by gas chromatography-mass spectrometry.  

PubMed

A simple and sensitive method based on a modified hollow-fiber liquid-phase microextraction followed by gas chromatography-mass spectrometry has been successfully developed for the extraction and simultaneous derivatization of some nitrophenols (NPs) in soil and rain samples. Microwave-assisted solvent extraction was used for the extraction of NPs from the soil, while the rain sample was directly applied to the previously mentioned method. Briefly, in this method, the analytes were extracted from aqueous samples into a thin layer of organic solvent (dodecane + 10% tri-n-octylphosphine oxide) sustained in the pores of a porous hollow fiber. Then, they were back-extracted using a small volume of organic acceptor solution (25 ?l; 10 mg/L N-methyl-N-(trimethylsilyl)trifluoroacetamide, as derivatization reagent, in acetonitrile) that was located inside the lumen of the hollow fiber. Under the optimized extraction conditions, enrichment factors of 255 to 280 and limits of detection of 0.1 to 0.2 ?g/L (S/N = 3) with dynamic linear ranges of 1-100 ?g/L were obtained for the analytes. The accuracy of the approach was tested by the relative recovery experiments on spiked samples, with results ranging from 93 to 113%. The method was shown to be rapid, cost-effective, and potentially interesting for screening purposes. PMID:23644691

Sobhi, Hamid Reza; Esrafili, Ali; Farahani, Hadi; Gholami, Mitra; Baneshi, Mohammad Mehdi

2013-11-01

365

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

PubMed

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

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

2013-01-01

366

Investigation of bioaccumulation profile of oestrogens in zebrafish liver by hollow fibre protected liquid phase microextraction with gas chromatography-mass spectrometric detection.  

PubMed

The applicability of hollow fibre protected liquid phase microextraction (HF-LPME) for the determination of three oestrogens, namely estrone (E1), 17?-estradiol (E2) and 17?-ethinylestradiol (EE2) from individual zebrafish liver samples, in a bioaccumulation study on these organisms, is reported. The oestrogens were extracted from single, mechanically crushed and minced livers from fish that were heaved in tubes containing water spiked at low concentration of the analytes. Extraction was performed with ?3 ?L of toluene contained in the hollow fibre. In order to achieve high extraction efficiency, the parameters that could affect the effectiveness of HF-LPME were optimized, i.e. the extracting organic solvent, extraction time, stirring speed and pH of the aqueous phase. For gas chromatography/mass spectrometry (GC/MS) analysis, injection port derivatization of the oestrogens with bis(trimethylsilyl)trifluoroacetamide was conducted. Under the most favourable extraction and derivatization conditions, enrichment factors of 158-279 were obtained. Linearity of the HF-LPME-GC/MS method was evaluated from 1 to 50 ?g/L and the coefficient of determination (r) ranged from 0.9687 to 0.9926. The LODs were between 0.017 and 0.033 ?g/L (at a signal to noise ratio of 3) with relative standard deviations (RSDs, analytes spiked at 5 ?g/L) of between 15 and 17% (n=3). PMID:23153642

Kanimozhi, Sivarajan; Basheer, Chanbasha; Neveliappan, Shanmugam; Ang, Kelvin; Xue, Feng; Lee, Hian Kee

2012-11-15

367

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

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

Lim, Hyun-Hee; Shin, Ho-Sang

2012-09-01

368

Identification and characterization of vinylpyrrolidone-vinylimidazolium chloride copolymers in cosmetic products by pyrolysis-gas chromatography-mass spectrometry method.  

PubMed

Synopsis Commercially available copolymers of 1-vinyl-2-pyrrolidone and 1-vinyl-3-methylimidazolium chloride, known as 'Luviquat' types in the cosmetic industry, were analysed for their composition using a combination of pyrolysis-gas chromatography-mass spectrometry method. This is a report on the determined pyrolytic products and the fast identification of the analysed polymers both in raw materials and cosmetic products. Calibration with defined material ensures the determination of monomer ratios with good reproducibility. Rsum Les copolymres de chlorure de 1-vinyle-2-pyrolidone et de 1-vinyle-3-methylimidazolium disponibles dans le commerce, connus dans l'industrie cosmtique sous la dnomination de copolymres de vinyle, ont t analyss laide d'une mthode combinant la pyrolyse, la spectromtrie de mass et la chromatographie en phase gazeuse. Cet article constitue un rapport sur les produits dtermins par pyrolyse et sur la rapidit d'identification des polymres analyss la fois dans des matires premires et dans des produits cosmtiques. Le calibrage avec un matriel dfini assure une bonne dtermination des taux de monomres dots d'une reproductibilit. PMID:19272122

Gmahl, E; Ruess, W

1993-04-01

369

Identification of volatile butyl rubber thermal-oxidative degradation products by cryofocusing gas chromatography/mass spectrometry (cryo-GC/MS).  

SciTech Connect

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.

Smith, Jonell Nicole; White, Michael Irvin; Bernstein, Robert; Hochrein, James Michael

2013-02-01

370

Determination of Wastewater Compounds in Whole Water by Continuous Liquid-Liquid Extraction and Capillary-Column Gas Chromatography/Mass Spectrometry  

USGS Publications Warehouse

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.

Zaugg, Steven D.; Smith, Steven G.; Schroeder, Michael P.

2006-01-01

371

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

SciTech Connect

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

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

2008-11-13

372

Determination of dissolved-phase pesticides in surface water from the Yakima River basin, Washington, using the Goulden large-sample extractor and gas chromatography/mass spectrometry  

USGS Publications Warehouse

Concentrations of pesticides in the dissolved phase of surface water samples from the Yakima River basin, WA, were determined using preconcentration in the Goulden large-sample extractor (GLSE) and gas chromatography/ mass spectrometry (GC/MS) analysis. Sample volumes ranging from 10 to 120 L were processed with the GLSE, and the results from the large-sample analyses were compared to those derived from 1-L continuous liquid-liquid extractions. Few of the 40 target pesticides were detected in 1-L samples, whereas large-sample preconcentration in the GLSE provided detectable levels for many of the target pesticides. The number of pesticides detected in GLSE processed samples was usually directly proportional to sample volume, although the measured concentrations of the pesticides were generally lower at the larger sample volumes for the same water source. The GLSE can be used to provide lower detection levels relative to conventional liquid-liquid extraction in GC/MS analysis of pesticides in samples of surface water. ?? 1993 American Chemical Society.

Foster, G.D.; Gates, P.M.; Foreman, W.T.; McKenzie, S.W.; Rinella, F.A.

1993-01-01

373

CODEX-compliant eleven organophosphorus pesticides screening in multiple commodities using headspace-solid phase microextraction-gas chromatography-mass spectrometry.  

PubMed

A headspace-solid phase microextraction-gas chromatography-mass spectrometric (HS-SPME-GC-MS, hereafter abbreviated as "SPME") method was developed for dedicated organophosphorus (OP) pesticides assessment in multiple vegetable and fruit commodities. Specific extraction variables were optimised to achieve harmonised extraction performance of eleven OPs in a great span of seven characteristic commodities cataloged in Codex Alimentarius Commission. Comprehensive validation study confirmed analytical robustness of the SPME treatment in turnip, green cabbage, French beans, eggplant, apple, nectarine and grapes. Based on range-specific evaluation, extraction of individual OPs was characterised by sub-ppb level sensitivity and a wide 0.01-2.5 mg L(-1) dynamic range. Effective sample clean-up afforded precise quantification (0.5-10.9% R.S.D.) within a 70-120% recovery range at the MRL levels specified for individual commodities. Compared to conventional methods currently used, the SPME treatment developed here is quick, accurate, and relatively environmental friendly; it represents an attractive, practical way to deliver international standards in OP screening routines. PMID:23122118

Sang, Zi-Ye; Wang, Yu-Ting; Tsoi, Yeuk-Ki; Leung, Kelvin Sze-Yin

2013-01-15

374

A rapid and simple procedure for the determination of cannabinoids in hemp food products by gas chromatography-mass spectrometry  

Microsoft Academic Search

A rapid and simple procedure using liquidliquid extraction and subsequent gas chromatographic mass-spectrometric detection has been developed for determination of ?9-tetrahydrocannabinol (THC), cannabidiol (CBD) and cannabinol (CBN) in different hemp foods. After addition of ?8-tetrahydrocannabinol as internal standard, both solid and liquid specimens were extracted with two volumes of 2ml of hexane\\/isopropanol (9:1): Chromatography was performed on a fused silica

Manuela Pellegrini; Emilia Marchei; Roberta Pacifici; Simona Pichini

2005-01-01

375

Determination of molecular species composition of C80 or longer-chain alpha-mycolic acids in Mycobacterium spp. by gas chromatography-mass spectrometry and mass chromatography.  

PubMed Central

The molecular species composition of alpha-mycolic acids ranging from C68 to C86 in 13 rapidly growing and 12 slowly growing mycobacterial species was determined by gas chromatography, gas chromatography-mass spectrometry, and mass chromatography. In gas chromatographic analysis, the molecular species of alpha-mycolic acids were well separated as trimethylsilyl ether derivatives of the methyl esters, according to their total carbon numbers. The total carbon and double-bond numbers of mycolic acids at each peak on gas chromatograms were determined from the [M]+, [M - 15]+, and [M - 90]+ ions on the mass spectrum, and straight and branched chain structures were identified by the mass fragment ions [A]+, due to C2--C3 cleavage [R-CH-O-Si(CH3)3]+, and [B]+, due to C3--C4 cleavage [(CH3)3-Si-O-CH-CH(R')-COOCH3]+. The concentration of odd- and even-carbon-numbered mycolic acids, which often overlap each other on gas chromatograms, and the composition of three homologous mycolic acids with different alpha units (C22:0, C24:0, and C26:0) were clearly determined by mass chromatography monitoring [M - 15]+ ions and [B - 29]+ ions, respectively. The molecular species composition of alpha-mycolic acids and their average carbon numbers (av. cn.) as a simple expression of the composition were calculated from the mass chromatograms. Each mycobacterial species examined was demonstrated to possess a characteristic profile of alpha-mycolic acid composition, and based on this the species were classified approximately into eight groups: C68 to C76 (av. cn. 72), dienoic, possessing a C20 alkyl branch at the 2 position (C22 alpha-unit) for Mycobacterium diernhoferi and Mycobacterium sp. strain 3707, a chromogenic rapid grower; C72 to C78 (av. cn. 75), dienoic with both C22 and C24 alpha units, containing a small or a large amount of odd-carbon-numbered molecules, for M. vaccae, M. rhodesiae, and M. phlei (chromogenic rapid growers); C72 to C80 (av. cn. 75 to 77), dienoic with C24 alpha-unit, containing a moderate or a large amount of odd-carbon-numbered molecules, for M. smegmatis, M. chitae, M. chelonae (M. chelonei), and M. fortuitum (nonchromogenic rapid growers); C78 to C82 (av. cn. 80), even-carbon-numbered dienoic with C24 alpha unit for M. agri and M. thermoresistible (rapid growers); C75 to C81 (av. cn. 77 to 79), odd-carbon-numbered dienoic with C24 alpha unit for M. nonchromogenicum complex (M. nonchromogenicum, M. terrae, and "M. novum") (slow growers); (vi) C76 to C84 (av. cn. 79 to 81), even-carbon-numbered dienoic with C24 alpha unit for MAIS complex including M. scrofulaceum, M. avium, and M. intracellulare (slow growers); (vii) C72 to C80 (av. cn. 77 to 79), even-carbon-numbered dienoic with C24 alpha unit for M. szulgai, M. gordonae, and M. kansasii (chromogenic slow growers); and (viii) C76 to C86 (av. cn. 79 to 81), even-carbon-numbered dienoic with C26 alpha unit M. bovis Ravenol and BCG and M. tuberculosis H37Rv. This study demonstrated that gas chromatography-mass spectrometric analysis of the molecular species composition of alpha-mycolic acid can give rapid, important, and very precise information for the identification of pathogenic and nonpathogenic mycobacterial species. Images PMID:3782454

Kaneda, K; Naito, S; Imaizumi, S; Yano, I; Mizuno, S; Tomiyasu, I; Baba, T; Kusunose, E; Kusunose, M

1986-01-01

376

Headspace analysis of volatile metabolites of Pseudomonas aeruginosa and related species by gas chromatography-mass spectrometry.  

PubMed Central

Gas chromatographic-mass spectrometric analysis of headspace volatiles was performed on cultures of 11 strains of Pseudomonas aeruginosa and 1 strain each of Pseudomonas cepacia, Pseudomonas putida, Pseudomonas putrefaciens, Pseudomonas fluorescens, and Pseudomonas maltophilia. All strains of Pseudomonas aeruginosa produced a distinctive series of odd-carbon methyl ketones, particularly 2-nonanone and 2-undecanone, and 2-aminoacetophenone. The other strains failed to produce 2-aminoacetophenone. Two sulfur compounds, dimethyldisulfide and dimethyltrisulfide, were present in strains of P. aeruginosa and in variable amounts in other species. Butanol, 2-butanone, 1-undecene, and isopentanol were also detected in P. aeruginosa cultures. PMID:6775012

Labows, J N; McGinley, K J; Webster, G F; Leyden, J J

1980-01-01

377

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

PubMed Central

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

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

2014-01-01

378

Hydrocarbons identified in extracts from estuarine water accommodated no. 2 fuel oil by gas chromatography-mass spectrometry  

NASA Technical Reports Server (NTRS)

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.

Lewis, B. W.; Walker, A. L.; Bieri, R. H.

1974-01-01

379

Airborne measurements of sulfur dioxide, dimethyl sulfide, carbon disulfide, and carbonyl sulfide by isotope dilution gas chromatography/mass spectrometry  

NASA Technical Reports Server (NTRS)

A gas chromatograph/mass spectrometer is described for determining atmospheric sulfur dioxide, carbon disulfide, dimethyl sulfide, and carbonyl sulfide from aircraft and ship platforms. Isotopically labelled variants of each analyte were used as internal standards to achieve high precision. The lower limit of detection for each species for an integration time of 3 min was 1 pptv for sulfur dioxide and dimethyl sulfide and 0.2 pptv for carbon disulfide and carbonyl sulfide. All four species were simultaneously determined with a sample frequency of one sample per 6 min or greater. When only one or two species were determined, a frequency of one sample per 4 min was achieved. Because a calibration is included in each sample, no separate calibration sequence was needed. Instrument warmup was only a few minutes. The instrument was very robust in field deployments, requiring little maintenance.

Bandy, Alan R.; Thornton, Donald C.; Driedger, Arthur R., III

1993-01-01

380

Chemical composition of Titan's aerosols analogues characterized with a systematic pyrolysis-gas chromatography-mass spectrometry characterization  

NASA Astrophysics Data System (ADS)

The in situ chemical characterization of Titan's atmosphere was achieved in 2005 with two instruments present onboard the Huygens atmospheric probe : the Aerosol Collector and Pyrolyzer (ACP) devoted to collect and pyrolyse Titan's aerosols ; the Gas Chromatograph-Mass Spectrometer (GCMS) experiment devoted to analyze gases collected in the atmosphere or coming from the aerosols pyrolysis. The GCMS was developed by Hasso Niemann in the filiation of the quadrupole mass spectrometers he built for several former space missions. The main objectives were to : determine the concentration profile of the most abundant chemical species; seek for minor atmospheric organic species not detected with remote observations ; give a first view of the organic aerosols structure; characterize the condensed volatiles present at the surface (e.g. lakes) in case of survival of the probe to the landing impact. Taking into account for the potential complexity of the gaseous samples to be analyzed, it was decided to couple to the MS analyzer a gas chromatograph capable to separate volatile species from light inorganic molecules and noble gases, to organic compounds including aromatics. This was the first GCMS analyzer that worked in an extraterrestrial environment since the Viking missions on Mars. Even if the GCMS coupling mode did not provide any result of interest, it has been demonstrated to be functional during the Huygens descent. But, the direct MS analysis of the atmosphere, and the pyrolysis-MS analysis of aerosols allowed to make great discoveries which are still of primary importance to describe the Titan's lower atmosphere composition. This contribution aims at presenting this instrument that worked in the Titan's atmosphere, and summarizing the most important discoveries it allowed.

Szopa, Cyril; Raulin, Francois; Coll, Patrice; Cabane, Michel; GCMS Team

2014-05-01

381

Sample Processing technique onboard ExoMars (MOMA) to analyze organic compounds by Gas Chromatography-Mass Spectrometry  

NASA Astrophysics Data System (ADS)

With the aim of separating and detecting organic compounds from Martian soil onboard the Mars Organic Molecule Analyzer (MOMA) experiment of the ExoMars 2018 upcoming joint ESA/NASA mission, we have developed three different space compatible sample preparation techniques compatible with space missions, able to extract and analyze by GC-MS a wide range of volatile and refractory compounds, including chirality analysis. Then, a sample processing utilizing three derivatization/extraction reactions has been carried out. The first reaction is based on a silyl reagent N-Methyl-N- (Tert-Butyldimethylsilyl)trifluoroacetamide (MTBSTFA) [1], the second one, N,N-Dimethylformamide Dimethylacetal (DMF-DMA) [2,3] is dedicated to the chirality detection and the third one is a thermochemolysis based on the use of tetramethylammoniumhydroxide (TMAH). The sample processing system is performed in an oven, dedicated to the MOMA experiment containing the solid sample (50-100mg). The internal temperature of the oven ranges from 20 to 900 C. The extraction step is achieved by using thermodesorption in the range of 100 to 300C for 5 to 20 min. Then, the chemical derivatization of the extracted compounds is performed directly on the soil sample by using a derivatyization capsule which contains a mixture of MTBSTFA-DMF or DMF-DMA solution when enantiomeric separation is required. By decreasing the polarity of the targeted molecules, this step allows their volatilization at a temperature below 250C without any thermal degradation. Once derivatized, the volatile target molecules are trapped in a chemical trap and promptly desorbed into the gas chromatograph coupled to a mass spectrometer. Thermochemolysis is directly performed in the oven at 400C during 5 min with a 25% (w/w) methanol solution of tetramethylammonium hydroxide (TMAH). Then, pyrolysis in the presence of TMAH allows both an efficient cleavage of polar bonds and the subsequent methylation of COOH, OH and NH2 groups, hence the release of less polar, GC-amenable compounds. By using thermochemolysis several families of biological molecules were detected such as fatty acids, n-alkenes and n-alkanols [4]. [1] A. Buch et al., Development of a gas chromatography compatible Sample Processing System (SPS) for the in-situ analysis of refractory organic matter in martian soil: preliminary result. Advances in Space Research 43, 143-151, 2009. [2] C. Freissinet et al., Journal of Chromatography A.1217 (5), 731-740, 2010. [3] U. Meierhenrich et al., Journal of Analytical and Applied Pyrolysis 60, 13-26, 2001. [4] C. Geffroy-Rodier et al., Journal of Analytical and Applied Pyrolysis, 85, 2009.

Buch, A.; Freissinet, C.; Sternberg, R.; Szopa, C.; Coll, P. J.; Brault, A.; Pinnick, V.; Siljestrm, S.; Raulin, F.; Steininger, H.; Goesmann, F.; MOMA Team

2011-12-01

382

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

USGS Publications Warehouse

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

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

2009-01-01

383

Lotus japonicus metabolic profiling. Development of gas chromatography-mass spectrometry resources for the study of plant-microbe interactions.  

PubMed

Symbiotic nitrogen fixation (SNF) in legume root nodules requires differentiation and integration of both plant and bacterial metabolism. Classical approaches of biochemistry, molecular biology, and genetics have revealed many aspects of primary metabolism in legume nodules that underpin SNF. Functional genomics approaches, especially transcriptomics and proteomics, are beginning to provide a more holistic picture of the metabolic potential of nodules in model legumes like Medicago truncatula and Lotus japonicus. To extend these approaches, we have established protocols for nonbiased measurement and analysis of hundreds of metabolites from L. japonicus, using gas chromatography coupled with mass spectrometry. Following creation of mass spectral tag libraries, which represent both known and unknown metabolites, we measured and compared relative metabolite levels in nodules, roots, leaves, and flowers of symbiotic plants. Principal component analysis of the data revealed distinct metabolic phenotypes for the different organs and led to the identification of marker metabolites for each. Metabolites that were enriched in nodules included: octadecanoic acid, asparagine, glutamate, homoserine, cysteine, putrescine, mannitol, threonic acid, gluconic acid, glyceric acid-3-P, and glycerol-3-P. Hierarchical cluster analysis enabled discrimination of 10 groups of metabolites, based on distribution patterns in diverse Lotus organs. The resources and tools described here, together with ongoing efforts in the areas of genome sequencing, and transcriptome and proteome analysis of L. japonicus and Mesorhizobium loti, should lead to a better understanding of nodule metabolism that underpins SNF. PMID:15749991

Desbrosses, Guilhem G; Kopka, Joachim; Udvardi, Michael K

2005-04-01

384

Study of disulfide reduction and alkyl chloroformate derivatization of plasma sulfur amino acids using gas chromatography-mass spectrometry.  

PubMed

Four disulfide-reducing agents, dithiothreitol (DTT), 2,3-dimercaptopropanesulfonate (DMPS), and the newly tested 2-mercaptoethanesulfonate (MESNA) and Tris(hydroxypropyl)phosphine (THP), were investigated in detail for release of sulfur amino acids in human plasma. After protein precipitation with trichloroacetic acid (TCA), the plasma supernatant was treated with methyl, ethyl, or propyl chloroformate via the well-proven derivatization-extraction technique and the products were subjected to gas chromatographic-mass spectrometric (GC-MS) analysis. All the tested agents proved to be rapid and effective reducing agents for the assay of plasma thiols. When compared with DTT, the novel reducing agents DMPS, MESNA, and THP provided much cleaner extracts and improved analytical performance. Quantification of homocysteine, cysteine, and methionine was performed using their deuterated analogues, whereas other analytes were quantified by means of 4-chlorophenylalanine. Precise and reliable assay of all examined analytes was achieved, irrespective of the chloroformate reagent used. Average relative standard deviations at each analyte level were ?6%, quantification limits were 0.1-0.2 ?mol L(-1), recoveries were 94-121%, and linearity was over three orders of magnitude (r(2) equal to 0.997-0.998). Validation performed with the THP agent and propyl chloroformate derivatization demonstrated the robustness and reliability of this simple sample-preparation methodology. PMID:22349320

Svagera, Zden?k; Hanzlkov, Dagmar; Simek, Petr; Huek, Petr

2012-03-01

385

Predicting feedstock and percent composition for blends of biodiesel with conventional diesel using chemometrics and gas chromatography-mass spectrometry.  

PubMed

The two main goals of the analytical method described herein were to (1) use principal component analysis (PCA), hierarchical clustering (HCA) and K-nearest neighbors (KNN) to determine the feedstock source of blends of biodiesel and conventional diesel (feedstocks were two sources of soy, two strains of jatropha, and a local feedstock) and (2) use a partial least squares (PLS) model built specifically for each feedstock to determine the percent composition of the blend. The chemometric models were built using training sets composed of total ion current chromatograms from gas chromatography-quadrupole mass spectrometry (GC-qMS) using a polar column. The models were used to semi-automatically determine feedstock and blend percent composition of independent test set samples. The PLS predictions for jatropha blends had RMSEC=0.6, RMSECV=1.2, and RMSEP=1.4. The PLS predictions for soy blends had RMSEC=0.5, RMSECV=0.8, and RMSEP=1.2. The average relative error in predicted test set sample compositions was 5% for jatropha blends and 4% for soy blends. PMID:22608455

Schale, Stephen P; Le, Trang M; Pierce, Karisa M

2012-05-30

386

Lotus japonicus Metabolic Profiling. Development of Gas Chromatography-Mass Spectrometry Resources for the Study of Plant-Microbe Interactions  

PubMed Central

Symbiotic nitrogen fixation (SNF) in legume root nodules requires differentiation and integration of both plant and bacterial metabolism. Classical approaches of biochemistry, molecular biology, and genetics have revealed many aspects of primary metabolism in legume nodules that underpin SNF. Functional genomics approaches, especially transcriptomics and proteomics, are beginning to provide a more holistic picture of the metabolic potential of nodules in model legumes like Medicago truncatula and Lotus japonicus. To extend these approaches, we have established protocols for nonbiased measurement and analysis of hundreds of metabolites from L. japonicus, using gas chromatography coupled with mass spectrometry. Following creation of mass spectral tag libraries, which represent both known and unknown metabolites, we measured and compared relative metabolite levels in nodules, roots, leaves, and flowers of symbiotic plants. Principal component analysis of the data revealed distinct metabolic phenotypes for the different organs and led to the identification of marker metabolites for each. Metabolites that were enriched in nodules included: octadecanoic acid, asparagine, glutamate, homoserine, cysteine, putrescine, mannitol, threonic acid, gluconic acid, glyceric acid-3-P, and glycerol-3-P. Hierarchical cluster analysis enabled discrimination of 10 groups of metabolites, based on distribution patterns in diverse Lotus organs. The resources and tools described here, together with ongoing efforts in the areas of genome sequencing, and transcriptome and proteome analysis of L. japonicus and Mesorhizobium loti, should lead to a better understanding of nodule metabolism that underpins SNF. PMID:15749991

Desbrosses, Guilhem G.; Kopka, Joachim; Udvardi, Michael K.

2005-01-01

387

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

PubMed Central

We develop a novel peak detection algorithm for the analysis of comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GCGC-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

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

2014-01-01

388

[Determination of ethyl glucuronide in human urine by solid phase extraction-gas chromatography-mass spectrometry].  

PubMed

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

Yu, Tianxiao; Li, Qing; Wan, Tao; Li, Jianbo; Ding, Shijia

2011-02-01

389

An alternative derivatization method for the analysis of amino acids in cerebrospinal fluid by gas chromatography-mass spectrometry.  

PubMed

The determination of the concentrations of l-amino acids in cerebrospinal fluid (CSF) has been used to gain biochemical insight into central nervous system disorders. This paper describes a microwave-assisted derivatization (MAD) method using N,O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA) as a derivatizing agent for determining the concentrations of l-amino acids in human CSF by gas chromatography with mass spectrometry (GC/MS). The experimental design used to optimize the conditions showed that the optimal derivatization time was 3min with a microwave power of 210W. The method showed good performance for the validation parameters. The sensitivity was very good, with limits of detection (LODs) ranging from 0.01?molL(-1) to 4.24?molL(-1) and limits of quantification (LOQs) ranging from 0.02 to 7.07?molL(-1). The precision, measured using the relative standard deviation (RSD), ranged from 4.12 to 15.59% for intra-day analyses and from 6.36 to 18.71% for inter-day analyses. The coefficients of determination (R(2)) were above 0.990 for all amino acids. The optimized and validated method was applied to the determination of amino acid concentrations in human CSF. PMID:23770739

de Paiva, Maria Jos Nunes; Menezes, Helvcio Costa; Christo, Paulo Pereira; Resende, Rodrigo Ribeiro; Cardeal, Zenilda de Lourdes

2013-07-15

390

Chemical characterisation of two Australian-grown strawberry varieties by using comprehensive two-dimensional gas chromatography-mass spectrometry.  

PubMed

The volatile compositions of two strawberry varieties ('Albion' and 'Juliette') grown in Australia were analysed with comprehensive two-dimensional gas chromatography (GCGC) combined with time-of-flight mass spectrometry (ToFMS). A suitable data processing method was created that should be sufficiently robust to compare sample chromatograms within a harvest season as well as between seasons with relative ease. Ninety-four compounds were tentatively or positively identified between the two varieties of which 20 have apparently not been previously reported to be components of strawberry volatiles. It was determined that Albion and Juliette have comparable total soluble solids content close to 11Brix. However, since Juliette exhibited a lower titratable acidity content than Albion, it consequently has a slightly larger sugar/acid ratio. The presence of 2,5-dimethyl-4-hydroxy-(2H)-furan-3-one (furaneol) was detected only in Juliette and this variety also had a higher area percentage of 2,5-dimethyl-4-methoxy-(2H)-furan-3-one (mesifuran), according to the sampling protocol. These experimental results offer possible explanations as to why Juliette is perceived to have a sweeter flavour than Albion. PMID:23870920

Samykanno, Kavitha; Pang, Edwin; Marriott, Philip J

2013-12-01

391

Determination of volatile oak compounds in wine by headspace solid-phase microextraction and gas chromatography-mass spectrometry.  

PubMed

A headspace solid-phase microextraction (HS-SPME) and gas chromatography (GC) coupled to mass spectrometry (MS) method was developed to identify and quantify 14 volatile oak compounds in aged red wines. The most important HS-SPME variables were optimised by experimental design technique in order to improved the extraction process. The selected conditions were: 10 mL of sample in 20 mL sealed vials with addition of 30% of sodium chloride (saturated solution), divinylbenzene-carboxen-polydimethylsiloxane (DVB-CAR-PDMS) fibre, 10 min of pre-incubation time, 70 degrees C of temperature and 60 min of extraction time without agitation. The features of the method were established for the studied compounds in terms of linear range, slope and intercept of the calibration graphs, detection and quantification limits and repeatability. For all compounds detection limits were below their threshold levels and repeatability, in terms of relative standard deviation, was good, with values between 3 and 11%. Finally, the method was applied to the analysis of six aged red wines by both internal standard and standard addition calibration methods. The concentrations obtained with both methods were statistically compared. PMID:16280128

Carrillo, Jos David; Garrido-Lpez, Alvaro; Tena, Mara Teresa

2006-01-13

392

The differentiation of fibre- and drug type Cannabis seedlings by gas chromatography/mass spectrometry and chemometric tools.  

PubMed

Cannabis cultivation in order to produce drugs is forbidden in Switzerland. Thus, law enforcement authorities regularly ask forensic laboratories to determinate cannabis plant's chemotype from seized material in order to ascertain that the plantation is legal or not. As required by the EU official analysis protocol the THC rate of cannabis is measured from the flowers at maturity. When laboratories are confronted to seedlings, they have to lead the plant to maturity, meaning a time consuming and costly procedure. This study investigated the discrimination of fibre type from drug type Cannabis seedlings by analysing the compounds found in their leaves and using chemometrics tools. 11 legal varieties allowed by the Swiss Federal Office for Agriculture and 13 illegal ones were greenhouse grown and analysed using a gas chromatograph interfaced with a mass spectrometer. Compounds that show high discrimination capabilities in the seedlings have been identified and a support vector machines (SVMs) analysis was used to classify the cannabis samples. The overall set of samples shows a classification rate above 99% with false positive rates less than 2%. This model allows then discrimination between fibre and drug type Cannabis at an early stage of growth. Therefore it is not necessary to wait plants' maturity to quantify their amount of THC in order to determine their chemotype. This procedure could be used for the control of legal (fibre type) and illegal (drug type) Cannabis production. PMID:20456880

Brosus, Julian; Anglada, Frdric; Esseiva, Pierre

2010-07-15

393

Nitrogen incorporation in Titan's tholins inferred by high resolution orbitrap mass spectrometry and gas chromatography-mass spectrometry  

NASA Astrophysics Data System (ADS)

Influx of solar photons and heavy charged particles from Saturn's magnetosphere on Titan's atmosphere - mainly comprised of methane and nitrogen - induce an intense organic photochemistry which leads to the formation of a large amount of aerosols in suspension in the atmosphere. In order to infer the role of nitrogen in aerosol formation processes we produced laboratory analogs of Titan's aerosols. In this work, we compare the composition of different analogs by using high resolution mass spectrometry and propose an additional study using gas-chromatography coupled to mass-spectrometry for a new kind of analog produced by polymerization of cryogenically trapped gaseous neutral species. The comparison of these materials emphasizes the importance of ion chemistry processes for the inclusion of nitrogen in molecules constituting Titan's tholins. A statistical approach is also used for the treatment of high resolution mass spectra of these highly complex organic materials. This method allows distinguishing molecular families that can be reconstructed by an ideal copolymer. We investigate several copolymer reconstructions, and we suggest that an HCN (or CH3CN)/C2H4 based copolymer agrees well with the polymeric structure of tholins produced with 5% of methane in nitrogen.

Gautier, Thomas; Carrasco, Nathalie; Schmitz-Afonso, Isabelle; Touboul, David; Szopa, Cyril; Buch, Arnaud; Pernot, Pascal

2014-10-01

394

Detection of high molecular weight organic tracers in vegetation smoke samples by high-temperature gas chromatography-mass spectrometry  

SciTech Connect

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 with mass spectrometry is not so common and application to aerosols is novel. The HTGC and HTGC-MS analyses of smoke samples taken by particle filtration from combustion of different species of plants provided the characterization of various classes of HMW compounds reported to occur for the first time in emissions from biomass burning. Among these components are a series of wax esters with up to 58 carbon numbers, aliphatic hydrocarbons, triglycerides, long chain methyl ketones, alkanols and a series of triterpenyl fatty acid esters which have been characterized as novel natural products. Long chain fatty acids with more than 32 carbon numbers are not present in the smoke samples analyzed. The HMW compounds in smoke samples from the burning of plants from Amazonia indicate the input of directly volatilized natural products in the original plants during their combustion. However, the major organic compounds extracted from smoke consist of a series of lower molecular weight polar components, which are not natural products but the result of the thermal breakdown of cellulose and lignin. In contrast, the HMW natural products may be suitable tracers for specific sources of vegetation combustion because they are emitted as particles without thermal alternation in the smoke and can thus be related directly to the original plant material.

Elias, V.O.; Simoneit, B.R.T. (Oregon State Univ., Corvallis, OR (United States)); Pereira, A.S.; Cardoso, J.N. (Univ. Federal do Rio de Janeiro (Brazil)); Cabral, J.A. (Inst. de Pesquisas da Amazonia, Amazonas (Brazil))

1999-07-15

395

Development of a gas chromatography-mass spectrometry method for the determination of pesticides in gaseous and particulate phases in the atmosphere.  

PubMed

A reliable multi-residue method for determining gaseous and particulate phase pesticides in atmospheric samples has been developed. This method, based on full scan gas chromatography-mass spectrometry (GC-MS), allowed the proper determination of sixteen relevant pesticides, in a wide range of concentrations and without the influence of interferences. The pesticides were benfluralin, bitertanol, buprofezin, chlorfenvinphos, chlorpyrifos, chlorpyrifos-methyl, ethalfluralin, fenthion, lindane, malathion, methidathion, propachlor, propanil, pyriproxifen, tebuconazol and trifluralin. Comparisons of two types of sampling filters (quartz and glass fibre) and four types of solid-phase cartridges (XAD-2, XAD-4, Florisil and Orbo-49P) showed that the most suitable supports were glass fibre filter for particulate pesticides and XAD-2 and XAD-4 cartridges for gaseous pesticides (>95% recovery). Evaluations of elution solvents for ultrasonic-assisted extraction demonstrated that isooctane is better than ethylacetate, dichloromethane, methanol or a mixture of acetone:hexane (1:1). Recovery assays and the standard addition method were performed to validate the proposed methodology. Moreover, large simulator chamber experiments allowed the best study of the gas-particle partitioning of pesticides for testing the sampling efficiency for the validation of an analytical multiresidue method for pesticides in air. Satisfactory analytical parameters were obtained, with a repeatability of 51%, a reproducibility of 133% and detection limits of 0.05-0.18 pg m(-3) for the particulate phase and 26-88 pg m(-3) for the gaseous phase. Finally, the methodology was successfully applied to rural and agricultural samples in the Mediterranean area. PMID:21704758

Borrs, E; Snchez, P; Muoz, A; Tortajada-Genaro, L A

2011-08-01

396

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

PubMed

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

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

2014-02-01

397

Determination of ultraviolet filters in water samples by vortex-assisted dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry.  

PubMed

For the first time, a simple solvent microextraction method termed vortex-assisted liquid-liquid microextraction (VADLLME) coupled with gas chromatography-mass spectrometry (GC-MS) has been developed and used for the analysis of six benzophenone ultraviolet (UV) filters (i.e. benzhydrol, 2,4-dihydroxybenzophenone, benzophenone, 2-hydroxy-4-methoxybenzophenone, ethylhexyl salicylate and homosalate) in water samples. The most favorable extraction variables in the VADLLME process were determined. In the extraction procedure, 40 ?L of tetrachloroethene as extraction solvent were directly injected into a 15-mL centrifuge tube containing 10 mL of aqueous sample, adjusted to pH 4 for VADLLME. After VADLLME, the extract was evaporated under a gentle nitrogen gas stream and then reconstituted with N,O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA), thus allowing the target analytes to be converted into their trimethylsilyl derivatives to optimize the GC-MS analysis. No centrifugation and disperser solvent were required in this microextraction procedure. Significantly, short extraction time and high extraction efficiency were achieved. This method opens up a potentially new horizon for on-site dispersive liquid-liquid microextraction. Under the optimum conditions, the proposed method provided good enrichment factors up to 310, with relative standard deviations ranging from 6.1 to 12.9%. The limits of quantification were in the range of 20-100 ng/L, depending on the analytes. The linearities were between 0.05 and 10 ?g/L and 0.1 and 10 ?g/L for different UV filters. Finally, the proposed method was successfully applied to the determination of UV filters from spiked genuine water samples and acceptable recoveries over the range of 71.0-120.0% were obtained. PMID:22749456

Zhang, Yufeng; Lee, Hian Kee

2012-08-01

398

[Determination of flumorph and dimethomorph residues in vegetables by improved QuEChERS-gas chromatography-mass spectromery].  

PubMed

To determine the residues of flumorph and dimethomorph in vegetables, a method was established with improved QuEChERS-gas chromatography coupled to mass spectrometry (GC-MS). With acetonitrile as the extraction solvent, the samples were pretreated with the improved QuEChERS method including extraction, salting-out and purification processes. Then all the sample extracts were analyzed with GC-MS in selected-ion monitoring (SIM) mode, and quantified by matrix-matched standard solution in external standard method. Under electron ionization conditions, the analysis was carried out with a capillary column (DB-5 MS, 30 mx 0. 25 mm x 0. 25 ?m) at a flow rate of 1. 1 mL/min. The quantitation was performed to detect ions of m/z 285, 371, 165 for flumorph and m/z 301, 387, 165 for dimethomorph. Good linearity was obtained in the range of 10-1 000 ?g/kg for both pesticides with correlation coefficients greater than 0. 999. The recovery experiments were carried out by spiking blank samples of ginger, tomato, carrot, spinach, cabbage and tremella at the three levels of 10, 20 and 100 ?g/kg. For both pesticides in different matrices, the limits of detection (S/N=3) were in the range of 0. 67-2. 42 ?g/kg. The average recoveries of flumorph and dimethomorph ranged from 71% to 116% with the relative standard deviations (RSDs) in the range of 1. 8%- 14. 7%. Meanwhile, the pyrolysis mechanism and matrix effect for the determination of flumorph and dimethomorph in vegetables were investigated in this study. The method is simple, rapid and accurate, and can be used for the routine analysis of flumorph and dimethomorph in vegetables. PMID:25507719

Ding, Liping; Cai, Chunping; Wang, Danhong

2014-08-01

399

[Determination of flumorph and dimethomorph residues in vegetables by improved QuEChERS-gas chromatography-mass spectromery].  

PubMed

To determine the residues of flumorph and dimethomorph in vegetables, a method was established with improved QuEChERS-gas chromatography coupled to mass spectrometry (GC-MS). With acetonitrile as the extraction solvent, the samples were pretreated with the improved QuEChERS method including extraction, salting-out and purification processes. Then all the sample extracts were analyzed with GC-MS in selected-ion monitoring (SIM) mode, and quantified by matrix-matched standard solution in external standard method. Under electron ionization conditions, the analysis was carried out with a capillary column (DB-5 MS, 30 mx 0. 25 mm x 0. 25 ?m) at a flow rate of 1. 1 mL/min. The quantitation was performed to detect ions of m/z 285, 371, 165 for flumorph and m/z 301, 387, 165 for dimethomorph. Good linearity was obtained in the range of 10-1 000 ?g/kg for both pesticides with correlation coefficients greater than 0. 999. The recovery experiments were carried out by spiking blank samples of ginger, tomato, carrot, spinach, cabbage and tremella at the three levels of 10, 20 and 100 ?g/kg. For both pesticides in different matrices, the limits of detection (S/N=3) were in the range of 0. 67-2. 42 ?g/kg. The average recoveries of flumorph and dimethomorph ranged from 71% to 116% with the relative standard deviations (RSDs) in the range of 1. 8%- 14. 7%. Meanwhile, the pyrolysis mechanism and matrix effect for the determination of flumorph and dimethomorph in vegetables were investigated in this study. The method is simple, rapid and accurate, and can be used for the routine analysis of flumorph and dimethomorph in vegetables. PMID:25434121

Ding, Liping; Cai, Chunping; Wang, Danhong

2014-08-01

400

Hyphenation of supercritical fluid chromatography and two-dimensional gas chromatography-mass spectrometry for group type separations.  

PubMed

The Fischer-Tropsch (FT) process produces a variety of compounds over a wide carbon number range and the synthetic crude oil produced by this process is rich in highly valuable olefins and oxygenates, which crude oil only contains at trace levels. The characterization of these products is very challenging even when using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GCGC-TOF-MS). The separation between cyclic paraffins and olefins is especially difficult since they elute in similar positions on the GCGC chromatogram and since they have identical molecular masses with indistinguishable fragmentation patterns. Previously, a high performance liquid chromatography (HPLC) fractionation procedure was used prior to GCGC-TOF-MS analysis to distinguish between alkenes and alkanes, both cyclic and non-cyclic, however, there was co-elution of the solvents used in the HPLC fractionation procedure, and the volatile components in the gasoline sample and the dilution introduced by the off-line fractionation procedure made it very difficult to investigate components present at very low concentrations. The hyphenation of supercritical fluid chromatography (SFC) to GCGC is less complicated and the removal of the supercritical CO2 can be easily achieved without any loss of the volatile sample components, eliminating the introduction of co-eluting solvents as well as the dilution effect. This paper describes the on-line hyphenation of SFC to a GCGC system in order to comprehensively characterize the chemical groups (saturates, unsaturates, oxygenates and aromatics) in an FT sample. PMID:23647609

Potgieter, H; van der Westhuizen, R; Rohwer, E; Malan, D

2013-06-14

401

Multiclass determination of 66 organic micropollutants in environmental water samples by fast gas chromatography-mass spectrometry.  

PubMed

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

Cherta, Laura; Beltran, Joaquim; Portols, Tania; Hernndez, Flix

2012-03-01

402

Detection of Mycobacterium tuberculosis in Sputum by Gas Chromatography-Mass Spectrometry of Methyl Mycocerosates Released by Thermochemolysis  

PubMed Central

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 tetramethylammon