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1

Gas chromatography-mass spectrometry (GC-MS) analysis of ...  

Treesearch

Title: Gas chromatography-mass spectrometry (GC-MS) analysis of ... trial using Gas Chromatography-Mass Spectrometry (GC-MS) detected differences in fatty acid ... methanol, chloroform, fatty acids, mass spectrometry, gas chromatography , ...

2

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

3

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

2013-07-19

4

Metabolism studies of chlormethiazole by gas chromatography-mass spectrometry  

Microsoft Academic Search

Summary The metabolic products of chlormethiazole were extracted from liver and isolated by thin layer chromatography. Chlormethiazole and three other products were obtained. One of these was identified earlier as being 4-methyl-5-?-hydroxy-ethylthiazole and now structures are proposed for the other two. A fourth metabolite, 4-methyl-5-thiazoleacetic acid, was formd in urine. The samples were analyzed by gas chromatography, gas chromatography-mass spectrometry

Roger Bonnichsen; Rolf Hjälm; Yvonne Mårde; Marianne Möller; Ragnar Ryhage

1973-01-01

5

Characterization of archaeological frankincense by gas chromatography–mass spectrometry  

Microsoft Academic Search

A simple gas chromatography–mass spectrometry (GC–MS) method has been developed for the characterization of frankincense in archaeological samples. After trimethylsilylation of the methanolic extract, 15 triterpenoids have been found among the chemical constituents of commercial olibanum (?-boswellic acid, 3-O-acetyl-?-boswellic acid, ?-boswellic acid, 3-O-acetyl-?-boswellic acid, ?-amyrin, ?-amyrin, lupeol, 3-epi-?-amyrin, 3-epi-?-amyrin, 3-epi-lupeol, ?-amyrenone, ?-amyrenone, lupenone, 3?-hydroxy-lup-20(29)-en-24-oic acid and 3-O-acetyl-hydroxy-lup-20(29)-en-24-oic acid). These compounds

Carole Mathe; Gérald Culioli; Paul Archier; Cathy Vieillescazes

2004-01-01

6

Serum xylose analysis by gas chromatography/mass spectrometry.  

PubMed

A gas chromatography/mass spectrometric (GC/MS) isotope dilution assay for xylose was developed using tertbutyldimethylsilyl-derivatized xylose and [13C]1xylose, and applied to human serum samples. A calibration curve in serum using this assay showed < 3% variation (< 10 mg/L) for any given point. The correlation coefficient for xylose measurements made on 27 sera between a colorimetric method performed by a national commercial reference laboratory and the GC/MS method developed here was .952. However, xylose determinations of 10 of 27 samples differed by > 10% (up to 150 mg/L) when colorimetric values were compared to GC/MS. Two of these samples had borderline-low xylose values by GC/MS, but were well within the normal range by colorimetric analysis. gas chromatography/mass spectrometric isotope dilution assay appears to be an accurate method to measure xylose in serum. These data also suggest that further prospective studies comparing GC/MS to colorimetric methods are indicated for subjects undergoing oral xylose testing. PMID:7942623

Deutsch, J C; Kolli, V R; Santhosh-Kumar, C R; Kolhouse, J F

1994-11-01

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

Field gas chromatography-mass spectrometry for fast analysis.  

PubMed

The objective of this presentation is to demonstrate the original device and procedure for fast gas chromatography-mass spectrometry (GC-MS) analysis of gaseous and liquid samples and to discuss its features and capabilities. The concept was developed in order to expand the range of compounds suitable for GC separation and to reduce the time of analysis. Field GC-MS, consisting of original "concentrator-thermodesorber" (CTD) unit, multiple module GC system and compact magnetic mass spectrometer with powerful two-stage vacuum system and multicollector ion detector, is represented. The whole weight of the device is 90 kg. Power consumption is 250 W. The device and analytical procedures allow high speed screening of toxic substances in air and extracts within 100 s per sample. The examples of applications are described, including fast screening of tributyl phosphate (TBP) in air at low ppt level at the rate 1 sample/min. PMID:14698236

Makas, Alexei L; Troshkov, Mikhail L

2004-02-01

9

Gas chromatography mass spectrometry-based metabolite profiling in plants.  

PubMed

The concept of metabolite profiling has been around for decades, but technical innovations are now enabling it to be carried out on a large scale with respect to the number of both metabolites measured and experiments carried out. Here we provide a detailed protocol for gas chromatography mass spectrometry (GC-MS)-based metabolite profiling that offers a good balance of sensitivity and reliability, being considerably more sensitive than NMR and more robust than liquid chromatography-linked mass spectrometry. We summarize all steps from collecting plant material and sample handling to derivatization procedures, instrumentation settings and evaluating the resultant chromatograms. We also define the contribution of GC-MS-based metabolite profiling to the fields of diagnostics, gene annotation and systems biology. Using the protocol described here facilitates routine determination of the relative levels of 300-500 analytes of polar and nonpolar extracts in approximately 400 experimental samples per week per machine. PMID:17406261

Lisec, Jan; Schauer, Nicolas; Kopka, Joachim; Willmitzer, Lothar; Fernie, Alisdair R

2006-01-01

10

Global urinary metabolic profiling procedures using gas chromatography–mass spectrometry  

Microsoft Academic Search

The role of urinary metabolic profiling in systems biology research is expanding. This is because of the use of this technology for clinical diagnostic and mechanistic studies and for the development of new personalized health care and molecular epidemiology (population) studies. The methodologies commonly used for metabolic profiling are NMR spectroscopy, liquid chromatography mass spectrometry (LC\\/MS) and gas chromatography–mass spectrometry

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

2011-01-01

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

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

EPA Science Inventory

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

13

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

14

Clinical applications of gas chromatography and gas chromatography–mass spectrometry of steroids  

Microsoft Academic Search

This review article underlines the importance of gas chromatography–mass spectrometry (GC–MS) for determination of steroids in man. The use of steroids labelled with stable isotopes as internal standard and subsequent analysis by GC–MS yields up to now the only reliable measurement of steroids in serum. Isotope dilution GC–MS is the reference method for evaluation of routine analysis of serum steroid

B. G. Wolthers; G. P. B. Kraan

1999-01-01

15

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 ...

16

The determination of impurities in caprolactam by capillary gas chromatography-mass spectrometry  

Microsoft Academic Search

A capillary gas chromatography-mass spectrometry (GC-MS) technique has been developed for the determination of impurities in caprolactam. The residual solution of the crude product extracted by benzene was analyzed. A total of 28 compounds in the residual solution were separated. In comparison with the mass spectra obtained with those published in data tables, 24 compounds of the 28 were identified.

Yuan-yuan Zhao; Zhi-zhong Jing; Hu-ping Li; Hua-shan Zhang

2001-01-01

17

Determination of polar pharmaceuticals in sewage water of Greece by gas chromatography–mass spectrometry  

Microsoft Academic Search

Sewage influents and effluents of different urban areas of Greece, were analyzed for polar pharmaceutical residues, used in human medicine. Drugs investigated were the anti-inflammatory drugs diclofenac and ibuprofen, the metabolite of the drugs clofibrates used as blood lipid regulators, clofibric acid and the analgesics phenazone and propyphenazone. Analysis was carried out using capillary gas chromatography–mass spectrometry with selected ion

V Koutsouba; Th Heberer; B Fuhrmann; K Schmidt-Baumler; D Tsipi; A Hiskia

2003-01-01

18

Evaluations of EUV resist outgassing by gas chromatography mass spectrometry (GC-MS)  

NASA Astrophysics Data System (ADS)

This paper summarizes the investigation of the evaluation methods of EUV resist outgassing based on pressure-rise, gas chromatography mass spectrometry (GC-MS) and quadrupole mass spectrometry (QMS). We discuss the merit and demerit about these three methods and propose an optimal employment of each evaluation method. In addition, detail results of resist outgassing evaluated from GC-MS were reported.

Oizumi, Hiroaki; Matsumaro, Kazuyuki; Santillan, Julius; Itani, Toshiro

2010-03-01

19

Gas chromatography-mass spectrometry in forensic chemistry for identification of substances isolated from tissue  

Microsoft Academic Search

Summary The use of combined gas chromatography-mass spectrometry in forensic chemistry is demonstrated in 13 cases where various substances had to be isolated and identified, the substance was present in small amounts in some samples while in others the sample available was very small. In other instances a rapid and certain identification was important. The results are compared with data

M. Blomquist; R. Bonnichsen; C.-G. Fri; Y. Mårde; R. Ryhage

1971-01-01

20

Combined Gas Chromatography/Mass Spectrometric Evaluation of Selected Isothermally Produced Shale Oils.  

National Technical Information Service (NTIS)

Liquid product samples generated by thermal decomposition of oil shale at 425 sup 0 C for time periods ranging from 10 to 120 minutes were evaluated using combined gas chromatography/mass spectrometry. This research effort was undertaken to determine if t...

F. D. Guffey

1986-01-01

21

Determination of Cyanide in Blood by Isotope Dilution Gas Chromatography-Mass Spectrometry  

Microsoft Academic Search

Background: Cyanide (CN) is a lethal toxin. Quantifi- cation in blood is necessary to indicate exposure from many sources, including food, combustion byproducts, and terrorist activity. We describe an automated proce- dure based on isotope-dilution gas chromatography- mass spectrometry (ID GC\\/MS) for the accurate and rapid determination of CN in whole blood. Methods: A known amount of isotopically labeled po-

Karen E. Murphy; Michele M. Schantz; Therese A. Butler; Bruce A. Benner; Laura J. Wood; Gregory C. Turk

22

Gas Chromatography-Mass Spectrometric Determination of Sarin Exposures in Human Serum by Fluoride Reactivation Method  

Microsoft Academic Search

The fluoride ion reactivation method was used to determine sarin exposures in human serum using the gas chromatography-mass spectrometry technique. The reaction and extraction conditions were systematically investigated and optimized to regenerate the maximum amount of sarin. The highest reactivation efficiency was 86%, which was calculated from the recovery of butyrylcholinesterase activity. For regenerated sarin over the inhibition of butyrylcholinesterase

Hai-Hong BAI; Lei GUO; Jian-Lin FENG; Feng Cui-Ling; Jia CHEN; Jian-Wei XIE

2008-01-01

23

Measurement of abscisic acid and gibberellins by gas chromatography/mass spectrometry.  

PubMed

Gas chromatography-mass spectrometry (GC-MS)-based analysis is an accurate and sensitive method to quantify plant hormones. This method is commonly used for analysis of low-molecular-weight compounds, such as abscisic acid (ABA), gibberellins (GAs), auxins, and brassinosteroids. Procedures are composed of four major steps: extraction, fractionation, derivatization, and detection. Here, we describe a protocol for quantification of ABA and GAs. PMID:19085147

Okamoto, Masanori; Hanada, Atsushi; Kamiya, Yuji; Yamaguchi, Shinjiro; Nambara, Eiji

2009-01-01

24

Pyrolysis-Gas Chromatography/Mass Spectrometry of Thermoplastic Polymers.  

National Technical Information Service (NTIS)

Thermal degradation mechanisms of ten thermoplastic polymers have been investigated using pyrolysis-gas chromatography with mass spectrometric and flame ionization detection. The results indicate that an unknown plastic can be identified on the basis of i...

J. A. Hiltz M. C. Bissonnette

1988-01-01

25

Simultaneous determination of cannabidiol, cannabinol, and \\\\gD 9 -tetrahydrocannabinol in human hair by gas chromatography-mass spectrometryin human hair by gas chromatography-mass spectrometry  

Microsoft Academic Search

An analytical method was developed for evaluating the cannabidiol (CBD), cannabinol, (CBN), and \\\\gD9-tetrahydrocannabinol (\\\\gD9-THC) level in human hair using gas chromatography-mass spectrometry (GC-MS). hair samples (50 mg) were washed with isopropyl\\u000a alcohol and cut into small fragments (<1 mm). After adding a deuterated internal standard, the hair, samples were incubated\\u000a in 1.0 M NaOH for 10 min at 95°C.

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

2005-01-01

26

Quantification of carbonate by gas chromatography-mass spectrometry.  

PubMed

Carbon dioxide and carbonates are widely distributed in nature, are constituents of inorganic and organic matter, and are essential in vegetable and animal organisms. CO(2) is the principal greenhouse gas in the atmosphere. In human blood, CO(2)/HCO(3)(-) is an important buffering system. Quantification of bicarbonate and carbonate in inorganic and organic matter and in biological fluids such as blood or blood plasma by means of the GC-MS technology has been impossible so far, presumably because of the lack of suitable derivatization reactions to produce volatile and thermally stable derivatives. Here, a novel derivatization reaction is described for carbonate that allows for its quantification in aqueous alkaline solutions and alkalinized plasma and urine. Carbonate in acetonic solutions of these matrices (1:4 v/v) and added (13)C-labeled carbonate for use as the internal standard were heated in the presence of the derivatization agent pentafluorobenzyl (PFB) bromide for 60 min and 50 °C. Investigations with (12)CO(3)(2-), (13)CO(3)(2-), (CH(3))(2)CO, and (CD(3))(2)CO in alkaline solutions and GC-MS and GC-MS/MS analyses under negative-ion chemical ionization (NICI) or electron ionization (EI) conditions of toluene extracts of the reactants revealed formation of two minor [i.e., PFB-OCOOH and O=CO(2)-(PFB)(2)] and two major [i.e., CH(3)COCH(2)-C(OH)(OPFB)(2) and CH(3)COCH=C(OPFB)(2)] carbonate derivatives. The latter have different retention times (7.9 and 7.5 min, respectively) but virtually identical EI and NICI mass spectra. It is assumed that CH(3)COCH(2)-C(OH)(OPFB)(2) is formed from the reaction of the carbonate dianion with two molecules of PFB bromide to form the diPFB ester of carbonic acid, which further reacts with one molecule of acetone. Subsequent loss of water finally generates the major derivative CH(3)COCH=C(OPFB)(2). This derivatization reaction was utilized to quantify total CO(2)/HCO(3)(-)/CO(3)(2-) (tCO(2)) in human plasma and urine by GC-MS in the NICI mode by selected ion monitoring of the anions [M-H](-) of CH(3)COCH=C(OPFB)(2) at m/z 461 for the endogenous species and m/z 462 for the internal standard (13)CO(3)(2-). Oral intake of the carboanhydrase inhibitor drug acetazolamide by two healthy volunteers resulted in temporary increased excretion of tCO(2) in the urine. The method is specific for carbonate, accurate, sensitive and should be applicable to various matrices including human fluids and environmental samples. PMID:20553048

Tsikas, Dimitrios; Chobanyan-Jürgens, Kristine

2010-10-01

27

[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

28

Analysis of autoxidized fats by gas chromatography-mass spectrometry: III. Methyl linolenate  

Microsoft Academic Search

The gas chromatography-mass spectrometry (GC-MS) method developed in the preceding papers was extended to the analysis of\\u000a autoxidation products of methyl linolenate. Four isomeric hydroxy allylic trienes with a conjugated diene system were identified\\u000a after reduction of the linolenate hydroperoxides. All eight geometrictrans,cis- andtrans, trans-conjugated diene isomers of these hydroxy allylic compounds were identified and partially separated by GC of

E. N. Frankel; W. E. Neff; W. K. Rohwedder; B. P. S. Khambay; R. F. Garwood

1977-01-01

29

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

Microsoft Academic Search

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

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

1998-01-01

30

Pyrolysis gas chromatography-mass spectrometry of natural resins used for artistic objects  

Microsoft Academic Search

Summary  Eight resins used as protective layers for paintings, small sculptures, jewelries and artistic furniture, namely, Manila copal,\\u000a colophony, Venice turpentine, elemi, shellac, dammar, sandarac and mastic were subjected to pyrolysis gas chromatography-mass\\u000a spectrometry (PY-GC-MS). Significant mass spectral ions were monitored in each pyrogram. A table for identification of such\\u000a resins based on the most significant ions in the mass spectra

G. Chiavari; D. Fabbri; R. Mazzeo; P. Bocchini; G. C. Galletti

1995-01-01

31

Chemical characterization of odorous gases at a landfill site by gas chromatography–mass spectrometry  

Microsoft Academic Search

The composition of odorous gases emitted from a municipal landfill in the city of Izmir, Turkey was investigated using gas chromatography–mass spectrometry, and these data were examined in relation with the odor concentrations. Several volatile organic compounds (VOCs) were identified and quantified at five sampling sites in May and September 2005. Detected VOCs were monoaromatics (0.09–47.42?gm?3), halogenated compounds (0.001–62.91?gm?3), aldehydes

Faruk Dincer; Mustafa Odabasi; Aysen Muezzinoglu

2006-01-01

32

Extraction of pure components from overlapped signals in gas chromatography-mass spectrometry (GC-MS)  

Microsoft Academic Search

Gas chromatography-mass spectrometry (GC-MS) is a widely used analytical technique for the identification and quantification of trace chemicals in complex mixtures. When complex samples are analyzed by GC-MS it is common to observe co-elution of two or more components, resulting in an overlap of signal peaks observed in the total ion chromatogram. In such situations manual signal analysis is often

Vladimir A Liki?

2009-01-01

33

Gas Chromatography\\/Mass Spectrometry Characterization of Corticosteroid Metabolism in Human Immortalized Keratinocytes  

Microsoft Academic Search

To continue our studies on the cutaneous expression of a proopiomelanocortin\\/corticotropin-releasing hormone system, we investigated whether this is accompanied by adrenal-type enzymatic activity. Immortalized cultured human keratinocytes were incubated with radiolabeled corticosteroids. Analysis by thin-layer chromatography showed rapid transformation of both progesterone and deoxycorticosterone; one of the progesterone metabolites migrated at the same rate as deoxycorticosterone. Gas chromatography\\/mass spectrometry further

Andrzej Slominski; Jacobo Wortsman; Mark F. Foecking; Cedric Shackleton; Celso Gomez-Sanchez; Andre Szczesniewski

2002-01-01

34

Improved accuracy and precision of gas chromatography\\/mass spectrometry measurements for metabolic tracers  

Microsoft Academic Search

The use of stable-isotope tracer methodology to study substrate metabolic kinetics requires accurate measurement of the tracer to tracee ratio (TTR), often by gas chromatography\\/mass spectrometry (GC\\/MS). Many approaches for measurement of the TTR by GC\\/MS do not use standards of known isotopic enrichment to control for variability in instrument response. In addition, most GC\\/MS applications exhibit some degree of

Bruce W. Patterson; Guohong Zhao; Samuel Klein

1998-01-01

35

Analysis of autoxidized fats by gas chromatography-mass spectrometry: II. Methyl linoleate  

Microsoft Academic Search

The gas chromatography-mass spectrometry (GC-MS) approach developed in the preceding paper was applied for qualitative and\\u000a quantitative investigations of autoxidation products of methyl linoleate. A GC-MS computer summation method was standardized\\u000a with synthetic 9- and 13-hydroxyoctadecanoate. Equal amounts of 9- and 13-hydroperoxides were found in all samples of linoleate\\u000a autoxidized at different temperatures and peroxide levels. The results are consistent

E. N. Frankel; W. E. Neff; W. K. Rohwedder; B. P. S. Khambay; R. F. Garwood; B. C. L. Weedon

1977-01-01

36

Analysis of autoxidized fats by gas chromatography-mass spectrometry: I. Methyl oleate  

Microsoft Academic Search

A structural investigation of autoxidation products of methyl oleate was carried out by gas chromatography-mass spectrometry\\u000a (GC-MS) of trimethylsilyl (TMS) ether derivatives. GC-MS using computer plots of selected masses afforded structural assignments\\u000a of GC peaks due to incompletely resolved mixtures. This method provided evidence of epoxy and keto esters which are not completely\\u000a separated from the main components consisting of

E. N. Frankel; W. E. Neff; W. K. Rohwedder; B. P. S. Khambay; R. F. Garwood; B. C. L. Weedon

1977-01-01

37

Assay of Aldehydes from Lipid Peroxidation: Gas Chromatography–Mass Spectrometry Compared to Thiobarbituric Acid  

Microsoft Academic Search

The oxidation of lipids, lipid peroxidation, is usually assayed with thiobarbituric acid (TBA). We compare the TBA assay measuring TBA-reactive substances (TBARS), and a new gas chromatography–mass spectrometric (GC–MS) assay measuring malondialdehyde (MDA) with unsaturated fatty acids and biological samples. The extent of oxidation to different unsaturated fatty acids is related to the total number ofbis-allylic positions, the position of

Jiankang Liu; Helen C. Yeo; Stephanie J. Doniger; Bruce N. Ames

1997-01-01

38

Determination of novolac resin thermal decomposition products by pyrolysis-gas chromatography-mass spectrometry  

Microsoft Academic Search

Pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) was used to identify the major volatile components produced by pyrolysis of a novolac resin. This resin is frequently used in the metal casting industry as a binder for sand molds. Quantitative analysis data of the pyrolysis products can serve as a model for the foundry industry to predict the amount of volatile organic compounds (VOCs)

C. A Lytle; W Bertsch; M McKinley

1998-01-01

39

Determination of chlorobenzenes in water by solid-phase extraction and gas chromatography–mass spectrometry  

Microsoft Academic Search

A method is described which permits the trace analysis of 10 chlorobenzenes in aqueous samples. Chlorobenzenes were extracted from water samples by solid-phase extraction with a C18 cartridge and analysis was carried out by gas chromatography–mass spectrometry in the selected-ion monitoring mode. The recovery and precision of the method were evaluated by extraction of spiked reagent-grade water at concentration levels

Yan Wang; Hian Kee Lee

1998-01-01

40

Characterisation of whiskeys using solid-phase microextraction with gas chromatography–mass spectrometry  

Microsoft Academic Search

The application of solid-phase microextraction and gas chromatography–mass spectrometry to the detection of flavour volatiles present in Irish and Scottish whiskeys was investigated. A method was developed to characterise these volatiles which included the extraction, identification and quantification of 17 congeners which included fusel alcohols, acetates and esters. The method validation produced the optimum fibre [85 ?m poly(acrylate)], extraction time

Gillian Fitzgerald; Kevin J James; Kevin MacNamara; Mary A Stack

2000-01-01

41

Determination of ajulemic acid and its glucuronide in human plasma by gas chromatography–mass spectrometry  

Microsoft Academic Search

A method using gas chromatography–mass spectrometry (GC–MS) and solid-phase extraction (SPE) was developed for the determination of ajulemic acid (AJA), a non-psychoactive synthetic cannabinoid with interesting therapeutic potential, in human plasma. When using two calibration graphs, the assay linearity ranged from 10 to 750ng\\/ml, and 750 to 3000ng\\/ml AJA. The intra- and inter-day precision (R.S.D., %), assessed across the linear

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

2005-01-01

42

Gas chromatography-mass spectrometry methods for structural analysis of fatty acids  

Microsoft Academic Search

Procedures for structural analysis of fatty acids are reviewed. The emphasis is on methods that involve gas chromatography-mass\\u000a spectrometry and, in particular, the use of picolinyl ester and dimethyloxazoline derivatives. These should be considered\\u000a as complementing each other, not simply as alternatives. However, additional derivatization procedures can be of value, including\\u000a hydrogenation and deuteration, and preparation of dimethyl disulfide and

William W. Christie

1998-01-01

43

Characterization of organic pollutants in industrial effluents by high-temperature gas chromatography–mass spectrometry  

Microsoft Academic Search

The characterization of complex mixtures of organic contaminants present in industrial effluents is a well-known problem. The determination of individual target analytes depends very much on the analytical method used. In this article, the possibilities of using high-temperature gas chromatography–mass spectrometry (HT-GC–MS) are explored. In HT-GC–MS non-polar and medium-polarity phases can be operated at temperatures up to 370–420°C, allowing the

A. S Pereira; F. R Aquino Neto

1999-01-01

44

Analytical characterization of natural waxes employing pyrolysis–gas chromatography–mass spectrometry  

Microsoft Academic Search

Three natural waxes (bleached beeswax, lanolin, yellow carnauba wax) were investigated by means of pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS). Pyrograms were obtained showing very characteristic signal patterns. Mass spectrometric detection enabled the structural identification of the pyrolytically formed fragments. For a more detailed investigation of the thermal degradation behaviour of waxy materials, relevant model compounds were selected. Hexadecylpalmitate, cholesterylstearate, heptadecanoic acid

Arndt Asperger; Werner Engewald; Gerd Fabian

1999-01-01

45

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

46

Determination of Dextromethorphan and its Metabolite Dextrorphan in Human Hair by Gas Chromatography–Mass Spectrometry  

Microsoft Academic Search

An analytical method has been developed for determination of dextromethorphan (DMP) and dextrorphan (DRP) in human hair by gas chromatography–mass spectrometry (GC–MS). Hair samples (30 mg) were washed with distilled water and acetone and cut into small fragments (?1 were in the range 90.6–97.2% with intra-assay and inter-assay precision of less than 5.7% and 4.7%, respectively. LOD and LOQ were,

Jin Young Kim; Sung Ill Suh; Ki-Jung Paeng; Moon Kyo In

2004-01-01

47

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

Microsoft Academic Search

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

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

1997-01-01

48

Extractive ethoxycarbonylation in high-temperature gas chromatography–mass spectrometry based analysis of serum estrogens  

Microsoft Academic Search

A comprehensive gas chromatography–mass spectrometry (GC–MS)-based profiling was developed as a practical assay for quantification of 18 endogenous estrogens in serum samples. The present GC–MS method was conducted with the two-phase extractive ethoxycarbonlyation (EOC) of the phenolic hydroxy groups of estrogen with ethyl chlorformate combined with the non-polar n-hexane extraction. The subsequent perfluoroacylation of aliphatic hydroxy groups with pentafluoropropionyl anhydride

Ju-Yeon Moon; Se Mi Kang; Myeong Hee Moon; Jongki Hong; Ki Tae Kim; Dae Hoon Jeong; Young Nam Kim; Bong Chul Chung; Man Ho Choi

49

Pyrolysis gas chromatography\\/mass spectrometry investigation of a thermally cured polymer  

Microsoft Academic Search

The curing of the Matrimid 5292® polyimide system was studied by pyrolysis-gas chromatography\\/mass spectrometry. Pyrolysis products characteristic of both initial components and the cured polymer were identified. Changes in the pattern of pyrolysis products could be related to the progress of polymerization. Amounts of methylphenol isomers (m\\/z 108), 4-succinimido-4?-aminodiphenylmethane (m\\/z 265), and 2-(2-propenyl)-4-methylphenol were found to increase as degree of

Randolph C. Galipo; William J. Egan; Jeffrey F. Aust; Michael L. Myrick; Stephen L. Morgan

1998-01-01

50

Effects of electron beam irradiation on cork volatile compounds by gas chromatography-mass spectrometry  

Microsoft Academic Search

Summary  The effects of electron beam irradiation on cork volatile compounds was studied at different doses (25, 100, 1000 kGy). Volatiles\\u000a were isolated from cork using the dynamic headspace-sampling technique, then identified by gas chromatography-mass spectrometry\\u000a (GC-MS). Similar gas chromatographic profiles were obtained for non-irradiated and irradiated corks. Quantitative differences\\u000a induced by the three doses were evaluated by calculating peak areas

M. Careri; V. Mazzoleni; M. Muscil; R. Molteni

1999-01-01

51

Analysis of radioactive mixed hazardous waste using derivatization gas chromatography/mass spectrometry, liquid chromatography, and liquid chromatography/mass spectrometry  

SciTech Connect

Six samples of core segments from Tank 101-SY were analyzed for chelators, chelator fragments, and several carboxylic acids by derivatization gas chromatography/mass spectrometry. The major components detected were ethylenediaminetetraacetic acid, nitroso-iminodiacetic acid, nitrilotriacetic acid, citric acid, succinic acid, and ethylenediaminetriacetic acid. The chelator of highest concentration was ethylenediaminetetraacetic acid in all six samples analyzed. Liquid chromatography was used to quantitate low molecular weight acids including oxalic, formic, glycolic, and acetic acids, which are present in the waste as acid salts. From 23 to 61% of the total organic carbon in the samples analyzed was accounted for by these acids.

Campbell, J.A.; Lerner, B.D.; Bean, R.M.; Grant, K.E.; Lucke, R.B.; Mong, G.M.; Clauss, S.A.

1994-08-01

52

Analysis of endogenous gibberellins and gibberellin metabolites from Dalbergia dolichopetala by gas chromatography-mass spectrometry and high-performance liquid chromatography-mass spectrometry  

Microsoft Academic Search

Qualitative gas chromatography-mass spectrometry (GC-MS) analysis of purified extracts from 4-d-germinated seeds of “jacarandá do cerrodo” (Dalbergia dolichopetala) detected gibberellin A1 GA1, epi-GA1 GA3, GA4, GA5, GA8, GA20 and G28. Quantitative analysis, using deuterated internal standards, showed that the germinated seed contained 29 ng GA1, 0.6 ng G4, 0.08 ng G5 and 1.7 ng GA20 · g-1 fresh weight. In

Thomas Moritz; Ana Maria Monteiro

1994-01-01

53

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

SciTech Connect

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

Bernhardt, J.

1995-08-23

54

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

Microsoft Academic Search

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

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

2010-01-01

55

Analysis of polyaromatic hydrocarbon mixtures with laser ionization gas chromatography/mass spectrometry  

SciTech Connect

Excimer laser induced multiphoton ionization has been utilized for ion generation in capillary gas chromatography/mass spectrometry and the technique applied to the separation and detection of polyaromatic hydrocarbons. Detection limits as low as 200 fg and linearity over a range of 5 x 10/sup +4/ were obtained for the polyaromatic hydrocarbons examined. Multiphoton ionization mass spectra were dominated by parent ions. Selective ionization based upon small differences in ionization potentials has been demonstrated for coeluting chrysene and triphenylene. Instrumental parameters have been investigated to assess improvements in sensitivity.

Rhodes, G.; Opsal, R.B.; Meek, J.T.; Reilly, J.P.

1983-02-01

56

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.

2013-10-01

57

Determination of leachable components from four commercial dental composites by gas and liquid chromatography\\/mass spectrometry  

Microsoft Academic Search

Objectives: The purpose of our study was to determine the quality and quantity of leachable residual (co)monomers and additives eluted from various commercial dental composite resins after polymerization.Methods: Polymerized specimens from four universal hybrid-type composite resins were eluted for 3 days with methanol resp. water. Then all extracts were analysed by gas chromatography\\/mass spectrometry or liquid chromatography\\/mass spectrometry using a

W. Spahl; H. Budzikiewicz; W. Geurtsen

1998-01-01

58

Detection of Several Classes of Pesticides and Metabolites in Meconium by Gas Chromatography-Mass Spectrometry  

PubMed Central

A solid phase extraction method was developed to isolate multiple classes of parent pesticides from meconium. A methanolic/hydrochloric acid methyl ester derivatization with liquid-liquid extraction technique was also developed for the analysis of metabolites. Identification and quantitation was by electron impact gas chromatography-mass spectrometry. For the parent compounds and metabolites, recoveries in spiked meconium ranged between 72–109%, with coefficients of variation ranging from 1.55–16.92% and limits of detection between 0.01–4.15 ?g g?1. Meconium samples obtained from infants in the Philippines were assayed using these methods, and propoxur, cypermethrin, pretilachlor, malathion, 4,4?-dichlorodiphenyltrichloroethylene, bioallethrin, and cyfluthrin were detected.

Bielawski, D.; Ostrea, E.; Posecion, N.; Corrion, M.; Seagraves, J.

2007-01-01

59

Analysis of serum bile acids by capillary gas--liquid chromatography--mass spectrometry.  

PubMed

A method for quantitative analysis of serum bile acids by capillary gas--liquid chromatography--mass spectrometry is described. The main features of this method are a Grob-type barium carbonate/polyethyleneglycol 20,000 glass capillary column, an all-glass capillary interface, use of the lipophilic anion exchanger DEAP-Sephadex-LH-20 for purification of the serum extract, and chenodeoxycholic-11,12-d2 acid as internal standard. Linearity of the response (ratio of intensities of the fragment ions diagnostic for the bile acid to be measured and for the internal standard) was demonstrated for four different bile acids. The method is sufficiently sensitive for measurement of bile acids in serum of healthy humans. PMID:7381330

Karlaganis, G; Schwarzenbach, R P; Paumgartner, G

1980-03-01

60

Quantitative analysis of trimethylsilyl derivative of hydroxyurea in plasma by gas chromatography-mass spectrometry.  

PubMed

Hydroxyurea is an antitumor drug widely used in the treatment of sickle cell disease. The drug has been analyzed in biological fluids by a number of high-performance liquid chromatography (HPLC) methods. This paper describes a fast and highly reliable capillary gas chromatography-mass spectrometry (GC-MS) procedure that was developed for the detection and quantitation of hydroxyurea in plasma. The compound and its labeled internal standard were liquid extracted from plasma and derivatized with BSTFA before analysis. The detection limit of the assay was 0.078 microg/ml and the limit of quantitation was 0.313 microg/ml with linearity up to 500 microg/ml. Intra-day variation, as coefficient of variation (C.V., %) over the selected concentration range, was 0.3-8.7% and inter-day variation was 0.4-9.6%. PMID:16378766

James, Hutchinson; Nahavandi, Masoud; Wyche, Melville Q; Taylor, Robert E

2005-12-27

61

Determination of delta9-THC in whole blood using gas chromatography-mass spectrometry.  

PubMed

A simple and reliable liquid-liquid extraction method for the determination of delta9-tetrahydrocannabinol (THC) in whole blood utilizing gas chromatography-mass spectrometry in electron impact mode is described. The substance is derivatized with pentafluoropropionic anhydride in pentafluropropanol. The limit of detection is 0.5 ng/mL for a 1-mL specimen, with recovery greater than 70%. The intra-assay coefficient of variation (CV) is 3.1% to 5.2%, and the interassay CV is 6.4% to 9.5%, calculated at THC concentrations of 1, 5, and 25 ng/mL. The accuracy is between 95 and 97%. The optimization of extraction and derivatization conditions is detailed. PMID:12501916

Chu, Mark Hok Chi; Drummer, Olaf H

62

Determination of tetrahydrozoline in urine and blood using gas chromatography-mass spectrometry (GC-MS).  

PubMed

Tetrahydrozoline, a derivative of imidazoline, is widely used for the symptomatic relief of conjunctival and nasal congestion; however, intentional or unintentional high doses can result in toxicity manifested by hypotension, tachycardia, and CNS depression. The detection of the drug in blood and urine is helpful in the diagnosis and management of a toxic patient. For the analysis, plasma, serum, or urine is added to a tube containing alkaline buffer and organic extraction solvents, and tetrahydrozoline from the sample is extracted into the organic phase by gentle mixing. After centrifugation, the upper organic solvent layer containing the drug is removed and dried under stream of nitrogen at 40 degrees C. The residue is reconstituted in a hexane-ethanol mixture and analyzed using gas-chromatography-mass spectrometry. Quantitation of the drug is done by comparing responses of unknown sample to the responses of the calibrators using selected ion monitoring. Naphazoline is used as an internal standard. PMID:20077102

Peat, Judy; Garg, Uttam

2010-01-01

63

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

PubMed

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

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

2011-05-01

64

A comparative study of the analysis of human urine headspace using gas chromatography-mass spectrometry.  

PubMed

First-void urine samples were obtained from 24 elderly, asymptomatic men (median age 62.9 years). The headspace above pH adjusted urine samples were extracted using a carboxen/polydimethylsiloxane solid phase micro-extraction fibre and the volatile organic compounds analysed by gas chromatography/mass spectrometry. A total of 147 compounds were identified in the headspace of urine. The acidified samples recorded a total of 92 compounds, 27 of which were ubiquitous, basified samples 70 compounds, with 12 ubiquitous and unmodified pH samples 49, with 6 ubiquitous. Five compounds were ubiquitous irrespective of pH: acetone, methylene chloride, 4-heptanone, 2-pentanone and 2-butanone. A comparative analysis of unfrozen and frozen-thawed urine (stored at room temperature for 0, 1 and 8 h) showed that samples retained the same number of compounds although variations in the peak areas for some compounds were observed. PMID:21386182

Smith, S; Burden, H; Persad, R; Whittington, K; de Lacy Costello, B; Ratcliffe, N M; Probert, C S

2008-09-08

65

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

PubMed

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

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

2010-07-01

66

Combined gas chromatography/mass spectrometric evaluation of selected isothermally produced shale oils  

SciTech Connect

Liquid product samples generated by thermal decomposition of oil shale at 425/sup 0/C for time periods ranging from 10 to 120 minutes were evaluated using combined gas chromatography/mass spectrometry. This research effort was undertaken to determine if the chemical composition of liquid products from kerogen decomposition was time dependent. Time-dependent change in the composition of the liquid products would indicate that kerogen decomposition follows reactions using intermediates of different chemical composition or structure. The results from the evaluation of the liquid products show more similarities than differences in chemical composition. This observation indicates that kerogen decomposition probably does not follow time-dependent reaction pathways using reaction intermediates of different chemical composition or structure. The minor differences noted in the samples do appear to be related to the time variable of the thermal decomposition experiments. 7 refs., 2 figs., 5 tabs.

Guffey, F.D.

1986-03-01

67

Triazinic herbicide determination by gas chromatography-mass spectrometry in breast milk.  

PubMed

A solid-phase extraction procedure using a graphitized carbon black cartridge for extraction and cleaning of a series of five triazines (atrazine, deethylatrazine, deisopropylatrazine, ametryne and prometryne) from breast milk samples was developed. Using a chemometric methodology, the optimisation of both the analysis time and the triazinic herbicide separation by gas chromatography-mass spectrometry (GC-MS) was then carried out with only 18 experiments. Detection and quantification limits for 1ml breast milk sample were, respectively, 0.3 and 1 ppb for each studied compound. The variation coefficients were less than 5% over the concentration range from 1 to 100 ppb. The accuracy was between 98.63 and 104.62% for each triazinic herbicide. The recovery was between 58.64 and 63.22% for the concentration range from 1 to 100 ppb for each triazinic herbicide. The assay was successfully applied to the analysis of several breast milk samples. PMID:12954391

Balduini, L; Matoga, M; Cavalli, E; Seilles, E; Riethmuller, D; Thomassin, M; Guillaume, Y C

2003-09-01

68

Improvements in bis(cyclopentadienyl)magnesium purity as determined with gas chromatography-mass spectroscopy  

SciTech Connect

Bis(cyclopentadienyl)magnesium (MgCp2) is used commonly as a source for doping nitride materials with magnesium. Increased oxygen incorporation known to accompany the use of MgCp2 makes the purity of this precursor an important consideration in nitride CVD. Gas chromatography-mass spectroscopy (GCMS) methods have now been developed for the identification of volatile impurities in MgCp2. Diethylether, an oxygen containing organic compound (CH{sub 3}CH{sub 2}OCH{sub 2}CH{sub 3}), and additional organic impurities were found in the MgCp2 supplied by three manufacturers. Subsequent refinements in the synthetic processes by these companies have resulted in the availability of MgCp2 free of ether and other organic impurities as determined by GCMS.

BARTRAM,MICHAEL E.

2000-03-08

69

[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

Bügler, Jürgen; Buchner, Hans; Dallmayer, Anton

70

Quantification of octachlorostyrene and related compounds in Great Lakes fish by gas chromatography - mass spectrometry  

SciTech Connect

Residues of octachlorostyrene (OCS) and related polychlorinated compounds including isomers of heptachloro-, hexachloro-, and pentachlorostyrene; hexachlorobenzene, pentachlorobenzene, isomers of tetrachloro- and trichlorobenzene; and hexachlorobutadiene have been quantitated by multiple-ion-detection gas chromatography-mass spectrometry in Great lakes fish collected between 1974 and 1980. The results show that the two upper lakes, Superior and Michigan, do not appear to have residues of OCS greater than 5 ng/g, while residues in the lower lakes, Huron, Ontario, and Erie, are as high as 400 ng/g. A selected tributary to Lake Erie has been shown to contain very high levels of all of the chemicals studied which suggests one possible source of chlorostyrenes in the Great Lakes.

Kuehl, D.W.; Johnson, K.L.; Butterworth, B.C.; Leonard, E.N.; Veith, G.D.

1981-01-01

71

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

ERIC Educational Resources Information Center

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

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

2005-01-01

72

Metabolism of isometheptene in human urine and analysis by gas chromatography–mass spectrometry in doping control  

Microsoft Academic Search

A study of the metabolism of isometheptene, an antispasmodic drug, in man and comparison with heptaminol metabolism, is presented in this paper. Isometheptene and two metabolites were detected in human urine after oral administration of a tablet containing isometheptene mucate. The urine level of the parent drug, which is excreted during the first 24h, was determined using gas chromatography–mass spectrometry,

Emmanouil Lyris; George Tsiakatouras; Yiannis Angelis; Michael Koupparis; Maria-Helen Spyridaki; Costas Georgakopoulos

2005-01-01

73

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

74

Screening of anthropogenic compounds in polluted sediments and soils by flash evaporation\\/pyrolysis gas chromatography-mass spectrometry  

Microsoft Academic Search

The use of flash evaporation and pyrolysis gas chromatography-mass spectrometry as a fast screening procedure for anthropogenic substances in environmental samples is demonstrated by the analysis of polluted soil and sediment samples. Polycyclic aromatic hydrocarbons, haloorganics, aliphatic hydrocarbons, heteroaromatics, elemental sulfur, cyanides, and pyrolysis products of synthetic polymers are among the anthropogenic substances that can be readily detected by this

J. W. de Leeuw; E. W. B. de Leer; J. S. Sinninghe. Damste; P. J. W. Schuyl

1986-01-01

75

Oxidized plant sterols in human serum and lipid infusions as measured by combined gas-liquid chromatography-mass spectrometry  

Microsoft Academic Search

Some oxidized forms of cholesterol (oxysterols) are thought to be atherogenic and cytotoxic. Because plant sterols are structurally related to cholesterol, we examined whether oxidized plant sterols (oxyphytosterols) could be identified in human serum and soy-based lipid emulsions. We first prepared both deuterated and nondeuterated reference compounds. We then analyzed by gas-liquid chromatography- mass spectrometry the oxyphytosterol concentrations in serum

Jogchum Plat; Harald Brzezinka; Dieter Lütjohann; Ronald P. Mensink; Klaus von Bergmann

76

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...

77

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

EPA Science Inventory

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

78

Solidphase microextraction coupled with gas chromatography and gas chromatography—Mass spectrometry for public health pesticides analysis  

Microsoft Academic Search

Summary  Public health pesticides in two-component mixed solutions were analyzed using solid-phase microextraction (SPME) coupled with\\u000a gas chromatography (GC) and gas chromatography—mass spectrometry (GC-MS). The two-component mixed solutions used were allethrin\\u000a mixed with cyfluthrin, cypermethrin mixed with tetramethrin, and transfluthrin mixed with cyfluthrin. Quantitative SPME-GC\\u000a and SPME-GC-MS analyses using calibration and standard addition methods were evaluated. Using SPME pretreatment saved several

C. BorFuh; Y. C. Yang; H. Y. Tsai; L. S. Ho

2003-01-01

79

Determination of succinonitrile in horse urine by gas chromatography-nitrogen-phosphorus detector and gas chromatography-mass spectrometry.  

PubMed

A chromatographic method was developed to detect and confirm the presence of succinonitrile (SDN) in horse urine samples, for antidoping control. The urine samples (5 ml) were extracted with diethyl ether and screened by gas chromatography-nitrogen-phosphorus detector and the confirmation of the drug's presence was accomplished by using gas chromatography-mass selective detection. The recovery of extraction was 78 and 81% for 1.0 and 2.0 micrograms ml-1 (relative standard deviation, < 10%), respectively. Urine samples collected after the administration of Energisan were positive for SDN (1-30 h) in all samples analysed. PMID:7879879

Pedroso, R C; Salvadori, M C; Andraus, M H; Lopez, N M

1994-12-01

80

Speciation of subsurface contaminants by cone penetrometry gas chromatography/mass spectrometry  

SciTech Connect

A thermal extraction cone penetrometry gas chromatography/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 collectors, the TECP extracts organics from soil without bringing the soil to the surface or into a collection chamber. Results show that polychlorinated biphenyls, polycyclic aromatic hydrocarbons (PAHs), chlorinated pesticides, and explosives can be recovered (60--95%) from wet or dry soil, with extraction efficiency compound-specific. The data are in remarkable agreement with closed cell thermal desorption (TD) experiments, where no organics are lost to the environment during heating. ECP GC/MS results also compare favorably with solvent-extracted GC/MS analyses and can be used to delineate the presence and extent of contamination at hazardous waste sites. Data illustrating TECP dependence on probe temperature and soil moisture as well as carrier gas liner velocity and volume (modified Reynolds number) are shown along with sample analysis data from two hazardous waste sites. The total ion and reconstructed ion current chromatograms are shown for PAHs collected by TECP from a coal tar contaminated soil obtained at a manufactured gas plant in Massachusetts. TECP and TD results are within 15% for nonvolatile PAHs and within 50% of the solvent-extracted data.

Gorshteyn, A.; Smarason, S.; Robbat, A. Jr. (Tufts Univ., Medford, MA (United States))

1999-07-15

81

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.  

National Technical Information Service (NTIS)

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...

J. W. Eichelberger E. H. Kerns P. Olynyk W. L. Budde

1983-01-01

82

The analysis of polar fractions from sediment extracts and crude oils using reaction-gas chromatography–mass spectrometry  

Microsoft Academic Search

Reaction-gas chromatography–mass spectrometry (R-GC–MS) has been used to analyse the polar fractions of sediment extracts and crude oils. Functionalised species were hydrogenolysed in the presence of hydrogen carrier gas, over a palladium black catalyst contained within the vapourising injector of a gas chromatograph-mass spectrometer. Model compound studies showed that the fully active catalyst was effective in hydrogenating and isomerising alkenes,

Carolyn M Sandison; Robert Alexander; Robert I Kagi

2003-01-01

83

Identification of sympathomimetic alkylamine agents in urine using liquid chromatography-mass spectrometry and comparison of derivatization methods for confirmation analyses by gas chromatography-mass spectrometry.  

PubMed

The detection of 11 sympathomimetic alkylamines in urine was presented with a focus on human doping control is proposed using liquid chromatography tandem mass spectrometry (LC-QqQ) and high resolution mass spectrometry (LC-HRMS) as a screening tool after a dilute-and-shoot (DS) approach. For the LC-HRMS analyses, several compounds exhibited better limits of detection (L.O.D.) than the LC-QqQ. However, due to their small differences in structure, co-elution among the alkylamines was observed. Therefore, the chemical conversion of the alkylamines into an appropriate derivative for the confirmation analyses using gas chromatography-mass spectrometry (GC-MS) was evaluated. Five derivatization approaches were evaluated in an attempt to increase the analytical response and the confidence of the identification. The choice of the appropriated derivative for each alkylamine makes their spectra more easily interpretable, fulfills the WADA's rather strict identification criteria and enables the unequivocal identification of alkylamines in urine. PMID:23746644

Sardela, Vinícius F; Sardela, Patrícia D O; Deventer, Koen; Araujo, Amanda L D; Cavalcante, Karina M; Padilha, Monica C; Pereira, Henrique M G; Van Eenoo, Peter; Aquino Neto, Francisco R

2013-05-13

84

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

85

Novel extraction of volatile biomarkers from canine breath for gas chromatography-mass spectrometry.  

PubMed

Here we describe an effective, reproducible, non-invasive volatile organic compound collection and analysis method for exhaled breath gas samples designed specifically for use with dogs. Conditions of the method were optimized, using a range of standard chemicals. This method utilizes a canine mask, two-way non-re-breathing valve, teflon connector, tubing and bag for sample collection. Collection is followed by condensation and headspace solid phase microextraction for sample concentration and gas chromatography-mass spectrometry for analysis. Custom-made glassware, designed to hold the SPME fiber assembly, was cooled to -10 °C and used for the collection of the condensate followed by 2 h of headspace extraction at 37 °C. Standards show LOD of 0.6-16.8 ppbv, LOQ between 2.1-55.8 ppbv, and good linearity with R(2) between 0.996-0.999 (RSD% 10-19). The method was verified with preliminary results from three dogs demonstrating that this technique is capable of collecting, identifying and quantifying volatile organic chemical constituents in different breath samples. PMID:22989995

Dissanayake, Shamitha; Lathan, Patty; Mlsna, Todd

2012-09-18

86

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

SciTech Connect

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

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

1999-07-20

87

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

88

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

89

Hydrocarbon gases emitted from vehicles on the road. 1. A qualitative gas chromatography\\/mass spectrometry survey  

Microsoft Academic Search

The gas-phase hydrocarbons greater than or equal to Câ generated by motor vehicles in highway operation were surveyed in the Allegheny Mountain Tunnel of the Pennsylvania Turnpike in 1979. The samples were collected on Tenax GC polymer adsorbent and analyzed by glass-capillary gas chromatography\\/mass spectrometry. Approximately 400 vehicle-generated compounds were detected. Of these, over 300 were either completely or partially

Christine V. Hampton; William R. Pierson; T. Michael Harvey; William S. Updegrove; Richard S. Marano

1982-01-01

90

Pyrolysis-gas chromatography\\/mass spectrometry used for screening polycyclic aromatic hydrocarbons by desorption from sediment  

Microsoft Academic Search

Pyrolysis-gas chromatography\\/mass spectrometry (Py-GC\\/MS) was evaluated as a fast economical screening technique for polycyclic aromatic hydrocarbons (PAHs) in sediment samples. A platinum filament pyroprobe was used for the analyses of PAHs ranging from naphthalene to benzo[a]pyrene. The effects of different temperatures, gas flows and times, solution port injections and interface injections, packed quartz tubes, open boats and ribbon volatilization were

Myriam Medina-Vera

1996-01-01

91

THE CHARACTERIZATION OF SULFONIUM CHLORIDES BY GAS CHROMATOGRAPHY\\/MASS SPECTROMETRY AND THE DEGRADATION OF 2-CHLOROETHYL SULFIDE DERIVATIVES  

Microsoft Academic Search

Three aqueous samples containing sulfonium chloride salts of both mustard gas (2,2?-dichlorodiethyl sulfide) and its simulant 2-chloroethyl ethyl sulfide have been characterized by gas chromatography\\/mass spectrometry (GC\\/MS). These salts decompose thermally to the corresponding 2-chloroethyl and 2-hydroxyethyl sulfides, therefore GC\\/MS analysis is not indicative of the true composition of these solutions. Small amounts of dithioethers characteristic of the decomposition of

Dennis K. Rohrbaugh; Yu-Chu Yang; J. Richard Ward

1989-01-01

92

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

PubMed

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

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

2013-03-13

93

Analysis of cholesterol oxidation products by Fast gas chromatography/mass spectrometry.  

PubMed

The aim of the present study was to set-up a Fast gas chromatography/mass spectrometry method for the analysis of cholesterol oxidation products (COPs). A silylated mixture of seven oxysterol standards was injected into a Fast GC/MS system. A capillary GC column (10?m×0.1?mm internal diameter×0.1??m film thickness) coated with 95% dimethyl- and 5% diphenyl-polysiloxane, was used. The method gave a fast (total analysis time=3.5?min) and satisfactory resolution (R>1.2) of the COPs standards, with a good repeatability and sensitivity, similar to those of conventional GC/MS; recoveries were tested on mice liver. Fast GC/MS method suitability for COPs analysis in food was also tested on an oxidized sardine fillet, which had been previously saponified and purified by NH(2) solid-phase extraction (SPE); a good repeatability and sensitivity was also obtained. The analytical performance of the Fast GC/MS method for the determination of COPs, together with the consequent significant reduction of the analysis time and consumables, demonstrates that Fast GC/MS represents a valid alternative to conventional GC/MS and evinces the great potential of such an analytical technique, which could be applied for both food and biological samples. PMID:22258809

Cardenia, Vladimiro; Rodriguez-Estrada, Maria T; Baldacci, Elena; Savioli, Stefano; Lercker, Giovanni

2012-02-01

94

Measurement of F2- isoprostanes and isofurans using gas chromatography-mass spectrometry.  

PubMed

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 nonenzymatic 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

2012-10-05

95

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

PubMed

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

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

2005-01-01

96

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

PubMed

Aminoglutethimide is used therapeutically as an aromatase inhibitor in the treatment of metastatic breast cancer in post-menopausal women. For doping purposes, aminoglutethimide may be used for treatment of adverse effects of an extensive abuse of anabolic androgenic steroids (gynaecomastia) and to increase the testosterone concentration and stimulation of testosterone biosynthesis. The use of aromatase inhibitors has been prohibited for male athletes since September 1, 2001. The purpose of this study was to develop methods for the identification of the parent compound or its main metabolite and the inclusion of this information into established screening procedures in doping analysis. An excretion study was conducted using oral application of one single therapeutic dose (500 mg) of Orimeten. The analysis was performed by gas chromatography/mass spectrometry (GC/MS). Aminoglutethimide is excreted almost totally as unconjugated parent compound and is detectable by different screening procedures for up to 165 h. Most suitable for the detection of aminoglutethimide is the screening procedure for heavy volatile nitrogen-containing drugs ('Screening 2'). However, since only competition samples are analysed in that screening procedure, the additional inclusion of aminoglutethimide in the screening procedure for anabolic androgenic agents ('Screening 4') is recommended. Full mass spectra and diagnostic ions for the analysis of aminoglutethimide are presented. PMID:12478562

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

2002-01-01

97

Determination of dialkyl phosphates in human urine using gas chromatography-mass spectrometry.  

PubMed

Organophosphates are used as pesticides in agriculture and pest control. They are metabolized to dialkylphosphates, which are excreted in urine. Determination of these metabolites is useful for assessing human exposure to organophosphates. This publication describes a new, reliable, and very sensitive analytical procedure for quantitating dimethylphosphate (DMP), diethylphosphate (DEP), O,O-dimethylthiophosphate (DMTP), O,O-diethylthiophosphate (DETP), O,O-dimethyldithiophosphate (DMDTP), and O,O-diethyldithiophosphate (DEDTP) in human urine. The analytes are extracted from acidified urine into a mixture of diethylether and acetonitrile. Dibutylphosphate serves as internal standard. Derivatization is performed using pentafluorobenzylbromide at 40 degrees C overnight. After further liquid-liquid extraction, analysis is carried out by gas chromatography-mass spectrometry. The limits of detection are 5 microg/L urine for DMP and 1 microg/L for the other five metabolites. Using the new procedure, 54 spot urine samples from persons in the general population in Germany were analyzed. Nearly every sample contained DMP, DEP, and DMTP, and the median values (95th percentiles) of the concentrations were 30 microg/L (105 microg/L), 4 microg/L (21 microg/L), and 22 microg/L (174 microg/L), respectively. DETP and DMDTP were found in lower concentrations. PMID:11110021

Hardt, J; Angerer, J

98

Determination of levamisole in urine by gas chromatography-mass spectrometry.  

PubMed

The United States Public Health Service Substance Abuse and Mental Health Services Administration is alerting medical professionals that a substantial percentage of cocaine imported into the United States is adulterated with levamisole, a veterinary pharmaceutical that can cause blood cell disorders such as severe neutropenia and agranulocytosis. Levamisole HCl is the active ingredient in a number of veterinary drugs approved to treat worm infestations in animals. Levamisole HCl was also the active ingredient in a human drug for oral administration approved on June 18, 1990, as adjuvant treatment in combination with fluorouracil after surgical resection in patients with Duke's stage C colon cancer. This drug was withdrawn from the U.S. market around 2000, and it has not been marketed in the U.S. since then. The objective of this study was to develop a method to determine the amount of levamisole in urine samples. The procedure will be provided to state health laboratories as needed to be used in the evaluation of patients that have developed neutropenia or agranulocytosis in the setting of recent cocaine use. A gas chromatography-mass spectrometry method was validated and tested at two different laboratories, and the method limit of detection for levamisole is 1 ng/mL in urine when using a 5-mL sample. Confirmation of the stereoisomer of levamisole was done by high-performance liquid chromatography using a chiral column. PMID:22004673

Trehy, Michael L; Brown, Daniel J; Woodruff, Jeffrey T; Westenberger, Benjamin J; Nychis, William G; Reuter, Nicholas; Schier, Joshua G; Vagi, Sara J; Hwang, Rong-Jen

2011-10-01

99

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

2010-03-30

100

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

2010-06-24

101

Quantification of phenyllactic acid in wheat sourdough using high resolution gas chromatography-mass spectrometry.  

PubMed

In this study, high-resolution gas chromatography-mass spectrometry (HRGC-MS) was successfully used to quantify the level of phenyllactic acid produced by Lactobacillus plantarum strains during sourdough fermentation. Investigation of samples collected during fermentation revealed that the production of phenyllactic acid occurs throughout the growth of L. plantarum in sourdough, but the highest production rate was observed during the logarithmic growth phase. The highest amount, that is, 33.47 mg of phenyllactic acid/kg of dough, was measured in sourdough fermented by the antifungal strain L. plantarum FST 1.7. Sourdoughs fermented by different L. plantarum strains contained different amounts of phenyllactic acid, thus indicating that the production is strain-dependent. Phenylacetic acid was also detected during sourdough analysis, thus showing that the HRGC-MS protocol developed is suitable for the detection not only of phenyllactic acid, but also of a broader range of phenolic acids that are highly relevant, but present in very low amounts in sourdough. PMID:19138118

Ryan, Liam Anthony Matthew; Dal Bello, Fabio; Czerny, Michael; Koehler, Peter; Arendt, Elke Karin

2009-02-11

102

[Determination of two mouldy compounds in cork by gas chromatography-mass spectrometry].  

PubMed

A simple and fast method for the simultaneous determination of two mouldy compounds, 2,4,6-trichloroanisole (TCA) and 2,4,6-tribromoanisole (TBA), in cork by gas chromatography-mass spectrometry (GC-MS) was established. The analytes were extracted by ultrasonic extraction with methanol, and purified then by solid phase extraction using primary secondary amine (PSA) as solid phase. After concentrating, the sample was analyzed by GC-MS and quantified by the external standard method. The linear ranges were from 10 microg/L to 10 000 microg/L for TCA and TBA, the correlation coefficients (r2) of the calibration curves were above 0.99. The recoveries and the relative standard deviations (RSDs) of TCA and TBA in different kinds of corks were investigated. The recoveries ranged from 88.4% to 97.6% with the RSDs between 1.02% and 4.58% (n = 6). The limits of detection (LODs) were 12 microg/L for TCA and 18 microg/L for TBA, and the limits of quantification (LOQs) were 40 microg/L for TCA and 50 microg/L for TBA. The method is suitable to the determination of TCA and TBA in corks. PMID:23189671

Tang, Xi; Liang, Ming; Li, Xiaojing; Xiong, Wenming; Tang, Hong; Jiang, Xiaoli; Chen, Jiamin

2012-07-01

103

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

Fryš, Ond?ej; ?esla, Petr; Bajerová, Petra; Adam, Martin; Ventura, Karel

2012-06-12

104

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

PubMed Central

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

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

2013-01-01

105

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?µg 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?; Puši?, Maja; Gajski, Goran; Garaj-Vrhovac, Vera

2011-10-28

106

A novel method for the determination of guanfacine in urine by gas chromatography-mass spectrometry.  

PubMed

Guanfacine (Tenex), an antihypertensive available since 1975, has recently been indicated for the treatment of attention deficit hyperactivity disorder in children (Intuniv). Because of this new usage, a gas chromatography-mass spectrometry method was developed and validated for the determination of guanfacine in urine. Guanfacine and 100 ng of protriptyline (internal standard) were extracted from 1.0 mL urine with 0.5 mL of saturated carbonate/bicarbonate buffer and 2 mL of ethyl acetate. The solvent extract was evaporated and derivatized with heptaflurobutyric anhydride in n-butyl chloride. Chromatographic separation was achieved using a DB-5 capillary column (30 m x 0.32 mm, 0.25 microm). Ions monitored for guanfacine were m/z 86.1, 272.1, and 274.1, and ions monitored for protriptyline were m/z 191.1 and 189.1. Concentrations were determined using calibrators over the range of 0.1-2.0 mg/L. The linear regression for all calibration curves had r2 values > or = 0.99. The limit of detection was 0.05 mg/L; limit of quantitation was 0.1 mg/L; and upper limit of linearity was 10.0 mg/L. Percent recovery of guanfacine at 0.1 and 2.0 mg/L was 93% and 71%, respectively. The method was found acceptable for routine quantitative analysis of guanfacine in urine. PMID:19007502

Haglock, Carrie; Wolf, Carl; Poklis, Alphonse

2008-10-01

107

Two-phase electromembrane extraction followed by gas chromatography-mass spectrometry analysis.  

PubMed

A two-phase electromembrane extraction (EME) was developed and directly coupled with gas chromatography mass spectrometry (GC-MS) analysis. The proposed method was successfully applied to the simultaneous determination of imipramine, desipramine, citalopram and sertraline. The model compounds were extracted from neutral aqueous sample solutions into the organic phase filled in the lumen of the hollow fiber. This method was accomplished with 1-heptanol as organic phase, by means of 60 V applied voltage and with the extraction time of 15 min. Experiments reported recoveries in the range of 69-87% from 1.2 mL neutral sample solution. The compounds were quantified by GC-MS instrument, with acceptable linearity ranging from 1 to 500 ng mL(-1) (R(2) in the range of 0.989 to 0.998), and repeatability (RSD) ranging between 7.5 and 11.5% (n = 5). The estimated detection limits (S/N ratio of 3:1) were less than 0.25 ng mL(-1). This novel approach based on two-phase EME brought advantages such as simplicity, low-costing, low detection limit and fast extraction with a total analysis time less than 25 min. These experimental findings were highly interesting and demonstrated the possibility of solving ionic species in the organic phase at the presence of electrical potential. PMID:23339011

Davarani, Saied Saeed Hosseiny; Morteza-Najarian, Amin; Nojavan, Saeed; Pourahadi, Ahmad; Abbassi, Mojtaba Beigzadeh

2013-01-22

108

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

PubMed

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

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

2012-12-03

109

Comparative analysis of mass spectral matching-based compound identification in gas chromatography-mass spectrometry.  

PubMed

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

Koo, Imhoi; Kim, Seongho; Zhang, Xiang

2013-05-13

110

[Study on the distribution and structure of polyhalides by gas chromatography-mass spectrometry].  

PubMed

A series of unexpected products were obtained when 1,4-dichloro-2-butyne reacted with allyl bromide with the catalyst PdCl2 (PhCN)2. It is difficult to separate these products from each other and to identify the structure of each one due to their similar properties. In order to solve this problem, gas chromatography-mass spectrometry (GC-MS) was chosen to analyse the above products because of its good sensitivity and selectivity. The analytical results showed that (A) the 8 compounds were 5,6-dichloro-4-chloromethyl-1, (E) 4-hexadiene (III), 5,6-dichloro-4-chloromethyl-1, (Z) 4-hexadiene (IV), 5-bromo-6-chloro-4-chloromethyl-1, (E) 4-hexadiene (V), 5-bromo-6-chloro-4-chloromethyl-1, (Z) 4-hexadiene (VI), 5-bromo-6-chloro-4-bromomethyl-1, (E) 4-hexadiene (VII), 5-bromo-6-chloro-4-bromomethyl-1, (Z) 4-hexadiene (VIII), 5,6-dibromo-4-bromomethyl-1, (E) 4-hexadiene (IX) and 5,6-dibromo-4-bromomethyl-1, (E) 4-hexadiene (X). Most compounds, except (V) and (VI), were the results of exchange reaction between chloride and bromide anion; each pair of the products are geometrical isomers. (B) in the four pairs of geometrical isomers, the ratio of Z-isomer/E-isomer decreased from 95:5 to 53:47 as molecular weight increased from compounds (III) and (IV) to compounds (IX) and (X). PMID:15739454

Jiang, H

1997-07-01

111

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-Jürgen

2007-07-24

112

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

PubMed

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

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

2005-03-01

113

Characterisation of whiskeys using solid-phase microextraction with gas chromatography-mass spectrometry.  

PubMed

The application of solid-phase microextraction and gas chromatography-mass spectrometry to the detection of flavour volatiles present in Irish and Scottish whiskeys was investigated. A method was developed to characterise these volatiles which included the extraction, identification and quantification of 17 congeners which included fusel alcohols, acetates and esters. The method validation produced the optimum fibre [85 microm poly(acrylate)], extraction time (35 min), sample volume size (3 ml) and desorption time (5 min). The impact of salt on the absorption process was also studied. Characteristic profiles were determined for each whiskey and the flavour congeners were quantified using 4-methyl-2-pentanol as the internal standard. Calibration ranges were determined for each of the congeners with coefficients of linearity ranging from 0.993 (butan-1-ol) to 0.999 (ethyl laurate) and relative standard deviations ranging from 2.5% (2-methylbutan-1-ol) to 21% (furfural) at a concentration of 18.2 mg/l. Detection limits ranged from 0.1 mg/l (ethyl caprate) to 21 mg/l (butan-2-ol). PMID:11093670

Fitzgerald, G; James, K J; MacNamara, K; Stack, M A

2000-10-27

114

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

PubMed

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

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

2012-11-16

115

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

2011-05-10

116

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

PubMed

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

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

2005-04-12

117

Neutrophil-mediated phospholipid peroxidation assessed by gas chromatography-mass spectroscopy.  

PubMed

Disease pathophysiology frequently involves manifestations of the systemic inflammatory response syndrome. Oxyradicals represent key inflammatory mediators, and neutrophils are one important source of oxyradicals. This investigation examined neutrophil-mediated peroxidation of dilinoleoyl phosphatidyl-choline (DLPC) liposomes by monitoring the appearance of monohydroxyl linoleic acid with the use of gas chromatography-mass spectroscopy (GC-MS), compared with traditional assessment of thiobarbituric acid-reactive species (TBARS) and phosphatidylcholine-specific conjugated dienes. DLPC was peroxidized in a system using activated neutrophils in balanced salt solution containing chelated iron. 9-Monohydroxyl linoleic acid and 13-monohydroxyl linoleic acid were readily identified in neutrophil-mediated peroxidized DLPC with the use of GC-MS. Neutrophil NADPH oxidoreductase specific activity correlated highly with total ion current or specific ion monitoring of integrated peak areas for peroxidized linoleic acid but correlated poorly with DLPC-derived TBARS or conjugated dienes. These results ascertain that activated neutrophils mediate phosphatidylcholine lipid peroxidation to specific products, which may be precisely monitored with the use of GC-MS. The extent of this peroxidation is highly correlated with the magnitude of the neutrophil respiratory burst. PMID:9277363

Zimmerman, J J; Ciesielski, W; Lewandoski, J

1997-08-01

118

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

PubMed

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

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

2005-09-01

119

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

SciTech Connect

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

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

1980-09-01

120

Extractive ethoxycarbonylation in high-temperature gas chromatography-mass spectrometry based analysis of serum estrogens.  

PubMed

A comprehensive gas chromatography-mass spectrometry (GC-MS)-based profiling was developed as a practical assay for quantification of 18 endogenous estrogens in serum samples. The present GC-MS method was conducted with the two-phase extractive ethoxycarbonlyation (EOC) of the phenolic hydroxy groups of estrogen with ethyl chlorformate combined with the non-polar n-hexane extraction. The subsequent perfluoroacylation of aliphatic hydroxy groups with pentafluoropropionyl anhydride (PFPA) was conducted. The serum samples were separated through a high temperature GC column (MXT-1) within an 8-min run and analyzed in selected-ion monitoring mode with good chromatographic properties for 18 estrogens as their EOC-PFP derivatives. The limit of quantification (LOQ) was 0.025-0.10 ng/mL for most estrogens analyzed except for E3 and 2-OH-E3 (0.5 ng/mL each). The devised method was found to be linear over a 10(3)-fold concentration range with a correlation coefficient (r(2)>0.992), whereas the precision (% CV) and accuracy (% bias) ranged from 3.1 to 16.3% and from 93.5 to 111.1%, respectively. Decreased 2-methoxy-17?-estradiol levels were confirmed in patients with preeclampsia than healthy pregnant women. This technique can be used for a clinical diagnosis as well as understanding the pathogenesis in estrogen-related disorders. PMID:22088353

Moon, Ju-Yeon; Kang, Se Mi; Moon, Myeong Hee; Hong, Jongki; Kim, Ki Tae; Jeong, Dae Hoon; Kim, Young Nam; Chung, Bong Chul; Choi, Man Ho

2011-10-29

121

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 (GC×GC-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, 20min 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 GC×GC-ToF-MS method were 0.09-2.92ng/L depending on the examined compound and matrix (compared to 0.1-13.3ng/L obtained using GC/MS(SIM)). For GC-MS/MS method lower detection limits were achieved than for the GC×GC method (0.01-0.1ng/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 2000ng/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

2013-07-26

122

PESTICIDE RESIDUE ANALYSIS OF DATE PALM FRUITS BY GAS CHROMATOGRAPHY MASS SPECTROPHOTOMETRY  

Microsoft Academic Search

Pesticides are being used indiscriminately to control insect pests of date palm (Phoenix dactylifera) such as red palm weevil, dubas bug, and mealy bug. The commercial formulation of several pesticides usually applied on date palm as root treatment, or injection into trunk, or as spray on foliage during flowering and fruiting stages to control insect pests. Green fruits of date

A. J. Khan; K. M. Azam; S. A. Razvi

123

Electron ionization gas chromatography–mass spectrometric determination of residues of thirteen pyrethroid insecticides in whole blood  

Microsoft Academic Search

A new rapid and sensitive electron ionization gas chromatography–mass spectrometry method in selective ion monitoring mode (SIM) was developed for the determination of l3 synthetic pyrethroid insecticide molecules and their stereo isomers in whole blood. The pyrethroid insecticides investigated are allethrin, bifenthrin, cypermethrin, cyphonothrin, cyfluthrin, lambda-cyhalothrin, deltamethrin, fenvalerate, fenpropathrin, imiprothrin, permethrin, prallethrin and transfluthrin. The residues of pyrethroids are extracted

Atmakuru Ramesh; Perumal Elumalai Ravi

2004-01-01

124

Identification of n-Decane Oxidation Products in Corynebacterium Cultures by Combined Gas Chromatography-Mass Spectrometry  

PubMed Central

The gas chromatography-mass spectrometry technique was employed to characterize n-decane oxidation products of Corynebacterium strains 7E1C and 269 (SNAM Progetti collection) after 73 h of incubation at 35 C. Corynebacterium 7E1C accumulated consistent amounts of esters of long chain acids with long chain alcohols, mainly decyldecanoate as well as products with mono- and diterminal carboxylic functions. Corynebacterium 269 yielded 1-decanol and 1-10 decanediol as principal oxidation products.

Bacchin, Paolo; Robertiello, Andrea; Viglia, Aurelio

1974-01-01

125

Gas chromatography–mass spectrometry of carbonyl compounds in cigarette mainstream smoke after derivatization with 2,4-dinitrophenylhydrazine  

Microsoft Academic Search

An improved gas chromatography–mass spectrometry (GC–MS) method was described for the analysis of carbonyl compounds in cigarette mainstream smoke (CMS) after 2,4-dinitrophenylhydrazine (DNPH) derivatization. Besides formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, methyl ethyl ketone, butyraldehyde, and crotonaldehyde that are routinely analyzed in cigarette smoke, this technique separates and allows the analysis of several C4, C5 and C6 isomeric carbonyl compounds. Differentiation

Ji-Zhou Dong; Serban C Moldoveanu

2004-01-01

126

Rapid identification of phenylenediamine isomers in henna hair dye products by gas chromatography?mass spectrometry (GC?MS)  

Microsoft Academic Search

This paper describes a gas chromatography?mass spectrometry (GC?MS) procedure for identification and quantitation of phenylenediamine isomers in eleven commercial and traditional henna hair dyes. Our results indicate that p?phenylenediamine (p?PD), the least toxic diamine isomer, is most commonly present in the hair dyes selected for this study. While relatively low levels of p?PD are observed in most commercial hair dyes,

Peter Krahn; Huda Hassan; Thomas Mahier; Afrozul Haq

1999-01-01

127

Analysis of volatile chemical components of Radix Paeoniae Rubra by gas chromatography-mass spectrometry and chemometric resolution  

Microsoft Academic Search

The volatile chemical components of Radix Paeoniae Rubra (RPR) were analyzed by gas chromatography-mass spectrometry with the method of heuristic evolving latent projections and\\u000a overall volume integration. The results show that 38 volatile chemical components of RPR are determined, accounting for 95.21%\\u000a of total contents of volatile chemical components of RPR. The main volatile chemical components of RPR are (Z,

Xiao-ru Li; Zheng-gang Lan; Yi-zeng Liang

2007-01-01

128

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

Microsoft Academic Search

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

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

2007-01-01

129

Optimization of pressurized liquid extraction and purification conditions for gas chromatography–mass spectrometry determination of UV filters in sludge  

Microsoft Academic Search

This work presents an effective sample preparation method for the determination of eight UV filter compounds, belonging to different chemical classes, in freeze-dried sludge samples. Pressurized liquid extraction (PLE) and gas chromatography–mass spectrometry (GC–MS) were selected as extraction and determination techniques, respectively. Normal-phase, reversed-phase and anionic exchange materials were tested as clean-up sorbents to reduce the complexity of raw PLE

N. Negreira; I. Rodríguez; E. Rubí; R. Cela

2011-01-01

130

Silicone discs as disposable enrichment probes for gas chromatography-mass spectrometry determination of UV filters in water samples  

Microsoft Academic Search

This work describes an effective, low solvent consumption and affordable sample preparation approach for the determination\\u000a of eight UV filters in surface and wastewater samples. It involves sorptive extraction of target analytes in a disposable,\\u000a technical grade silicone disc (5 mm diameter?×?0.6 mm thickness) followed by organic solvent desorption, large volume injection\\u000a (LVI), and gas chromatography-mass spectrometry determination. Final working conditions involved

N. Negreira; I. Rodríguez; E. Rubí; R. Cela

2011-01-01

131

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

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

2000-01-01

132

Detection of more than 50 substituted phenols as their t-butyldimethylsilyl derivatives using gas chromatography-mass spectrometry  

Microsoft Academic Search

More than 50 substituted phenols have been derivatized successfully with N-(t-butyldimethylsilyl)-N-methyltrifluoroacetamide (MTBSTFA) by forming their t-butyldimethylsilyl derivatives. The study included 21 chlorinated phenols, 13 nitrophenols, 3 aminophenols, 4 alkylphenols, o-phenylphenol, the non-substituted phenol and some other substituted phenols including six phenolic pesticides. The determination and detection of the derivatives were performed by capillary gas chromatography-mass spectrometry. The mass spectra of

Thomas Heberer; Hans-Juergen Stan

1997-01-01

133

Electropolymerization of chlorinated phenols on a Pt electrode in alkaline solution. Part IV: A gas chromatography mass spectrometry study  

Microsoft Academic Search

The electropolymerization of phenol and chlorinated phenols (monochlorophenols, dichlorophenols, 2,3,6-, 2,4,6-, 2,4,5-trichlorophenols and pentachlorophenol) was studied on a platinum electrode at 0.78 V vs SHE in alkaline 1 M NaOH aqueous solutions containing 0.1 M of the phenols. The low molecular weight reaction products were investigated by means of gas chromatography mass spectrometry (GCMS). Product analyses show that oligomers (dimers,

Z. Ežerskis; Z. Jusys

2002-01-01

134

A rapid and simple procedure for the determination of ephedrine alkaloids in dietary supplements by gas chromatography–mass spectrometry  

Microsoft Academic Search

A simple method for the determination of ephedrine alkaloids: ephedrine (EF), pseudoephedrine (PE), norpseudoephedrine (NPE), norephedrine (NE) and methylpseudoephedrine (MPE) in dietary supplements by gas chromatography–mass spectrometry is described. After the addition of 3,4-methylenedioxypropylamphetamine as internal standard, a liquid–liquid extraction procedure in alkaline conditions with chloroform\\/isopropanol (9:1, v\\/v) was applied to the samples prior to analysis. Chromatography was performed on

Emilia Marchei; Manuela Pellegrini; Roberta Pacifici; Piergiorgio Zuccaro; Simona Pichini

2006-01-01

135

Determination of dichloromethane, trichloroethylene and perchloroethylene in urine samples by headspace solid phase microextraction gas chromatography–mass spectrometry  

Microsoft Academic Search

A method for the determination of volatile chlorinated hydrocarbons, namely dichloromethane (DCM), trichloroethylene (TCE), and perchloroethylene (PCE), in urine samples was developed using headspace solid phase microextraction (HS-SPME) gas chromatography–mass spectrometry (GC–MS). HS-SPME was performed using a 75?m Carboxen-polydimethylsiloxane fiber. Factors, which affect the HS-SPME process, such as adsorption and desorption times, stirring, salting-out effect, and temperature of sampling have

Diana Poli; Paola Manini; Roberta Andreoli; Innocente Franchini; Antonio Mutti

2005-01-01

136

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

Microsoft Academic Search

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

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

137

Determination of steroids and coprostanol in surface water, effluent and mussel using gas chromatography-mass spectrometry  

Microsoft Academic Search

Summary  A method was developed for the determination of coprostanol and steroids, including estradiol-17?, estrone and testosterone\\u000a in surface water, effluent and mussels. The method is based on the derivatization of steroids containing hydroxyl groups with\\u000a pentafluorobenzyl bromide (PFB-Br), followed by gas chromatography-mass spectrometric (GC-MS) determination. Estradiol-17?\\u000a and estrone were successfully derivatized by this method, whereas coprostanol (a sterol compound) and

S. Cathum; H. Sabik

2001-01-01

138

Construction of calibration-locking databases for rapid and reliable drug screening by gas chromatography-mass spectrometry  

Microsoft Academic Search

Unique calibration-locking databases were constructed for rapid and semiquantitative drug screening by gas chromatography-mass\\u000a spectrometry (GCMS). In addition to the free-drug database of 127 drugs, a drug database with acetylating reagents was constructed\\u000a to increase the number of detectable compounds in the analysis by GC-MS; 156 drugs, including 30 drugs of abuse, 42 hypnotics\\u000a and their metabolites, 18 antipsychotic drugs,

Keiko Kudo; Tomomi Ishida; Wakako Hikiji; Makiko Hayashida; Kyoko Uekusa; Yosuke Usumoto; Akiko Tsuji; Noriaki Ikeda

2009-01-01

139

Townsend discharge nitric oxide chemical ionization gas chromatography/mass spectrometry for hydrocarbon analysis of the middle distillates  

SciTech Connect

Hydrocarbon type analysis of petroleum distillates (350-860 {degrees}F fraction) was performed using Townsend discharge nitric acid chemical ionization gas chromatography/mass spectrometry (TDNOCI GC/MS). Both n and z in the chemical formula, C{sub n}H{sub 2n + z} can be determined. GC separation allows quantification of heteroatom compounds in the presence of aromatics of the same mass. Results are presented for the analysis of feedstocks and hydrotreated products.

Dzidic, I.; Petersen, H.A.; Wadsworth, P.A.; Hart, H.V. [Westhollow Research Center, Houston, TX (United States)

1992-10-01

140

Determination of airborne trialkyl and triaryl organophosphates originating from hydraulic fluids by gas chromatography–mass spectrometry  

Microsoft Academic Search

Methodology for personal occupational exposure assessment of airborne trialkyl and triaryl organophosphates originating from hydraulic fluids by active combined aerosol and vapor sampling at 1.5L\\/min is presented. Determination of the organophosphates was performed by gas chromatography–mass spectrometry. Combinations of adsorbents (Anasorb 747, Anasorb CSC, Chromosorb 106, XAD-2 and silica gel) with an upstream cassette with glass fiber or PTFE filters

K. Solbu; S. Thorud; M. Hersson; S. Øvrebø; D. G. Ellingsen; E. Lundanes; P. Molander

2007-01-01

141

The identification of synthetic organic pigments in modern paints and modern paintings using pyrolysis-gas chromatography–mass spectrometry  

Microsoft Academic Search

A collection of more than 70 synthetic organic pigments were analysed using pyrolysis-gas chromatography–mass spectrometry\\u000a (Py-GC–MS). We report on the analysis of diketo-pyrrolo-pyrrole, isoindolinone and perylene pigments which are classes not\\u000a previously reported as being analysed by this technique. We also report on a number of azo pigments (2-naphthol, naphthol\\u000a AS, arylide, diarylide, benzimidazolone and disazo condensation pigments) and phthalocyanine

Joanna Russell; Brian W. Singer; Justin J. Perry; Anne Bacon

2011-01-01

142

Lipopolysaccharide core region of Hafnia alvei: structure elucidation using chemical methods, gas chromatography-mass spectrometry, and NMR spectroscopy  

Microsoft Academic Search

Sugar and methylation analysis with the use of gas chromatography-mass spectrometry and 1H NMR spectroscopy proved that the core oligosaccharides isolated from lipopolysaccharides of eight Hafnia alvei strains have the identical hexasaccharide skeleton. However, 1H, 31P heterocorrelated spectra showed that the phosphorylation pattern is not the same. The branched heptose for the ATCC 13337, 1187, 2, 1191, 1196, 1220, and

Andrzej Gamian; Ewa Katzenellenbogen; Elzbieta Romanowska; Ursula Dabrowski; Janusz Dabrowski

1995-01-01

143

Investigation of the reaction products of unsymmetrical dimethylhydrazine with potassium permanganate by gas chromatography-mass spectrometry  

Microsoft Academic Search

The gas chromatography-mass spectrometry technique was used to investigate the composition of the reaction products of unsymmetrical\\u000a dimethylhydrazine with a potassium permanganate and potassium permanganate-hydrogen peroxide mixture. If the water contamination\\u000a level is within 50 threshold limit values (TLV) (1 mg\\/ml), the proposed detoxication method utilizing potassium permanganate\\u000a in combination with hydrogen peroxide allows for the reduction of the UDMH

A. K. Buryak; T. M. Serdyuk; A. V. Ul’yanov

2011-01-01

144

Determination of 1,3-dichloropropanol in soy and related sauces by using gas chromatography\\/mass spectrometry  

Microsoft Academic Search

A gas chromatography\\/mass spectrometry method for 3-MCPD in foods and food ingredients was modified for the determination of 1,3-DCP in soy and related sauces. The method was validated by using a blank soy sauce. The detection limit, quantitation limit and recoveries were determined, and identities were confirmed by mass spectrometry on the basis of analyses of test portions spiked with

P. J. Nyman; G. W. Diachenko; G. A. Perfetti

2003-01-01

145

Revised method for routine determination of urinary dialkyl phosphates using gas chromatography-mass spectrometry.  

PubMed

Among urinary organophosphorus pesticide (OP) metabolites, dialkyl phosphates (DAPs) have been most often measured as a sensitive biomarker in non-occupational and occupational OP exposure risk assessment. In our conventional method, we have employed a procedure including simple liquid-liquid extraction (diethyl ether/acetonitrile), derivatization (pentafluorobenzylbromide, PFBBr) and clean-up (multi-layer column) for gas chromatography-mass spectrometry (GC-MS) analysis starting from 5-mL urine samples. In this study, we introduce a revised analytical method for urinary DAPs; its main modification was aimed at improving the pre-derivatization dehydration procedure. The limits of detection were approximately 0.15 microg/L for dimethylphosphate (DMP), 0.07 microg/L for diethylphosphate (DEP), and 0.05 microg/L for both dimethylthiophosphate (DMTP) and diethylthiophosphate (DETP) in 2.5-mL human urine samples. Within-run precision (percent of relative standard deviation, %RSD) at the DAP levels varying in the range of 0.5-50 microg/L was 6.0-19.1% for DMP, 3.6-18.3% for DEP, 8.0-25.6% for DMTP and 9.6-27.8% for DETP. Between-run precision at 5 microg/L was below 15.7% for all DAPs. The revised method proved to be feasible to routine biological monitoring not only for occupational OP exposure but also for environmental background levels in the general population. Compared to our previous method, the revised method underscores the importance of adding pre-derivatization anhydration for higher sensitivity and precision. PMID:20207202

Ueyama, Jun; Kamijima, Michihiro; Kondo, Takaaki; Takagi, Kenji; Shibata, Eiji; Hasegawa, Takaaki; Wakusawa, Shinya; Taki, Tomoko; Gotoh, Masahiro; Saito, Isao

2010-02-12

146

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.

Bengtsson, Goran; Annadotter, Helene

1989-01-01

147

Cannabichromene and tetrahydrocannabinol determination in mouse blood and brain by gas chromatography-mass spectrometry.  

PubMed

Cannabichromene (CBC) is a phytocannabinoid, the second most abundant cannabinoid quantitatively in marijuana. CBC has been shown to produce antinociception and anti-inflammatory effects in rodents. This method is validated for the measurement of THC and CBC simultaneously after extraction from mouse blood or brain. Whole brain harvested from mice was homogenized 2:1 (v/w) with normal saline. Fifty nanograms of THC-d? was added to 0.5 mL of heparinized mouse blood, brain homogenate, and THC and CBC fortified blood or brain calibrators, then equilibrated overnight at 5 °C. Two milliliters of "ice cold" acetonitrile was added drop-wise while the sample was vortex mixed, and then the sample was centrifuged and stored overnight at -30 °C. The cannabinoids were extracted from the acetonitrile layer with 2 mL of 0.2 N NaOH and 4 mL of hexane/ethyl acetate (9:1). The solvent was isolated and evaporated to dryness. Trimethylsilyl derivatives were prepared and then analyzed by gas chromatography-mass spectrometry. Linearity in blood and brain of THC and CBC was 2-10,000 ng/mL (ng/g). THC and CBC recovery ranged from 56 to 78% in blood and brain. Precision was demonstrated at 100 ng/mL and 1000 ng/mL with CVs < 15%. The validated method allows for blood and brain concentrations of cannabinoids to be quantificated and correlated with pharmacological effects produced in mice. PMID:21871159

DeLong, Gerald T; Wolf, Carl E; Poklis, Alphonse; Lichtman, Aron

2011-09-01

148

Comprehensive impurity profiling and quantification of Sudan III dyes by gas chromatography/mass spectrometry.  

PubMed

A novel analysis strategy was created for comprehensive qualitative and quantitative impurity profiling of the coloring agent Sudan III by gas chromatography/mass spectrometry (GC/MS). The identification of impurities in commercial Sudan III was performed by GC/MS combined with trimethylsilylation (TMS). A total of 24 impurities were identified or tentatively characterized in commercial Sudan III dyes by GC/MS and were mainly classified as phenylazo and naphtholazo analogs. Four new impurities with coplanar structures, suspected of being toxic compounds, were observed in commercial Sudan III dyes. For further identification and sensitive detection of polar impurities, an extract was trimethylsilyl-derivatized to improve the GC chromatographic properties and mass spectrometric detection sensitivity. On the basis of the impurities identified by GC/MS, pathways for the formation of the major impurities during the manufacture of Sudan III were suggested. Four impurities regulated by the EU commission and the US Code of Federal Regulations (CFR) in Sudan III were quantified by GC/MS-scan mode. Method validation was conducted to determine linearity, precision, accuracy, and limit of quantification (LOQ). The linear dynamic range extended from 0.001 to 4.0%, with a correlation coefficient (R(2)) greater than 0.997 for GC/MS. The LOQs of the impurities ranged from 2.73 to 4.39?g/g for GC/MS. Based on the established method, the levels of regulated impurities in five commercial Sudan III dyes manufactured by different chemical companies were successfully determined. This study provides very useful information for the quality control of Sudan III and evaluation of its manufacture. PMID:23726074

Hong, Ji Yeon; Park, Na Hyun; Yoo, Kyung Ho; Hong, Jongki

2013-04-29

149

Determination of herbicides by solid phase extraction gas chromatography-mass spectrometry in drinking waters.  

PubMed

A solid phase extraction (SPE) method has been optimized for the gas chromatography-mass spectrometry (GC-MS) simultaneous determination of herbicides belonging to the following different families: carbamate (molinate), atrazines (atrazine, propazine, simazine, ametryne, cyanazine, terbutylazine, deethylterbutylazine, deethylatrazine), dinitroaniline (trifluralin, pendimethalin), chloroacetamide (alachlor, metolachlor). Different solid substrates have been compared (C18, cyano, styrene-divinylbenzene, phenyl, graphitic carbon). The type of conditioning and elution solvent, its volume, and the sample flow rate have been considered as variables affecting the recovery yields of the herbicides. The optimized experimental conditions are C18 phase conditioned with 3 mL acetone, loaded with 1L water sample at 5 mL min(-1), and eluted with 3 mL acetone. Good recoveries (included between 79% and 99%) and R.S.D. (included between 2% and 12%) have been obtained for all analytes, except for deethylatrazine whose recovery was 46+/-7%. The recovery of deethylatrazine increases up to 94+/-17% if a non-porous graphitic carbon is coupled to the C18 phase, keeping the other parameters constant as optimized. The optimized method has been successfully checked for the identification and quantitation of the selected herbicides in raw and drinking water samples, with quantitation limits as low as 0.01 microg L(-1), fully in agreement with the current legislation. The method is easily routinable. After development, the method is currently routinely applied for the analysis of herbicides in waters and, up today, more than one thousand samples have been analysed at the "Laboratorio della Società Metropolitana Acque di Torino" (Laboratory of the Municipal Waterworks of Turin) in charge of the control of drinking water quality in Torino. PMID:17723718

Bruzzoniti, M C; Sarzanini, C; Costantino, G; Fungi, M

2006-06-30

150

[Simultaneous determination of 19 phthalate esters in cosmetics using gas chromatography-mass spectrometry].  

PubMed

A method was developed for the simultaneous determination of 19 phthalate esters (PAEs) at trace level in cosmetics by solid phase extraction (SPE) purification and gas chromatography-mass spectrometry (GC-MS) detection. The PAEs were extracted from cosmetic samples by dichloromethane with ultrasonic-assisted technique, purified by an SPE column packed with silica gel and neutral alumina (2: 3, m/m) with the elution of 20 mL of mixed solvent of ethyl acetate-hexane (8: 2, v/v). Qualitative and quantitative analysis were carried out by GC-MS in full scan and selected ion monitoring modes. The retention time of quantitative ions and the abundance ratio of characteristic ions were applied to rapidly and accurately identify each analyte so as to prevent the occurring of possible mistakes from complex matrix intervention. Under optimized conditions, the average recoveries for a shampoo sample spiked with the standards at 0.1, 0.5, 2.0 microg/g were in the range of 72.2% and 110.9%, and the relative standard deviations (RSDs) for the 19 PAEs were less than 10.3% (n = 6) at the spiked level of 0.1 microg/g. The limits of detection (LODs, as 3 times of standard deviation) were between 0.0065 microg/g (for diisopentyl phthalate) and 0.062 microg/g (for diisobutyl phthalate). The method was successfully applied to the determination of the PAEs in 6 types of cosmetics. It is expected to promote the determination of the PAEs in other cosmetics with different matrices. PMID:22715693

Liang, Jing; Zhuang, Wan'e; Wei, Danqi; Ou, Yan; Gong, Zhenbin

2012-03-01

151

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

152

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

PubMed

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

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

2008-07-01

153

Simultaneous determination of psychotropic phenylalkylamine derivatives in human hair by gas chromatography/mass spectrometry.  

PubMed

A gas chromatography/mass spectrometric (GC/MS) method was developed and validated for the determination of thirteen psychotropic phenylalkylamine derivatives (amphetamine; AP, phentermine; PT, methamphamine; MA, cathinone; Khat, methcathinone; MCAT, fenfluramine; FFA, desmethylselegiline; DSEL, 3,4-methylenedioxyamphetamine; MDA, 3,4-methylenedioxymethamphetamine; MDMA, 3,4-methylenedioxyethylamphetamine; MDEA, norketamine; NKT, mescaline; MES, 4-bromo-2,5-dimethoxyphenethylamine; 2CB) in human hair. Hair samples (20 mg) were washed with distilled water and acetone, cut into small fragments (<1 mm), and incubated in 0.25 M methanolic HCl under ultrasonication at 50 degrees C for 1 h. The resulting solutions were evaporated to dryness, derivatized using trifluoroacetic anhydride (TFAA) at 70 degrees C for 30 min, and analyzed by GC/MS. The linear ranges were 0.02-25.0 ng/mg for AP, PT, Khat, FFA, DSEL, MDMA, and 2CB; 0.05-25.0 ng/mg for MA, MCAT, and MES; 0.05-12.5 ng/mg for MDA; and 0.1-25.0 ng/mg for MDEA and NKT, with good correlation coefficients (r(2) > 0.9985). The intra-day, inter-day, and inter-person precisions were within 12.7%, 14.8%, and 16.8%, respectively. The intra-day, inter-day, and inter-person accuracies were between -10.7 and 13.4%, -12.7 and 11.6%, and -15.3 and 11.9%, respectively. The limits of quantifications (LOQs) for each compound were lower than 0.08 ng/mg. The recoveries were in the range of 76.7-95.6%. The method proved to be suitable for the simultaneous qualification and quantification of phenylalkylamine derivatives in hair specimens. PMID:17474080

Kim, Jin Young; Jung, Kyu Sung; Kim, Min Kyoung; Lee, Jae Il; In, Moon Kyo

2007-01-01

154

Rapid analysis of benzoylecgonine in urine by fast gas chromatography-mass spectrometry.  

PubMed

A novel fast gas chromatography-mass spectrometry (FGC-MS) analytical method for benzoylecgonine (BZE) has been developed to improve the efficiency of specimen analysis without diminishing the reliability of metabolite identification and quantification. Urine specimens were spiked with deuterated internal standard (BZE-d8), subjected to solid-phase extraction, and derivatized with pentafluoropropionic anhydride (PFPA) and pentafluoropropanol (PFPOH). The pentafluoropropyl ester derivative of BZE was identified and quantified using both a standard GC-MS method and the newly developed FGC-MS method. Shorter GC analyte retention times were made possible in the FGC-MS method by employing a 220-volt GC oven controller, which allowed an increased temperature ramp rate. The FGC-MS method was linear between 25 and 10,000 ng/mL of BZE yielding a correlation coefficient of 0.9994. The intra-assay precision of a 100 ng/mL BZE standard (n=15) yielded an average concentration of 99.7 ng/mL and a coefficient of variation of 1.2%. The interassay precision of 21 sets of 50, 100, and 125 ng/mL BZE controls was found to be acceptable, with coefficients of variation less than 2.4%. No interference was observed when the FGC-MS method was challenged with cocaine, ecgonine, ecgonine methyl ester, and nine other drugs of abuse. Analysis of presumptively positive specimens (n=146) by both analytical methods yielded comparable results with a correlation coefficient of 0.996. The FGC-MS method, when compared with a standard GC-MS method, reduces total assay time by approximately 50% while demonstrating comparable reliability. PMID:17132251

Romberg, Robert W; Jamerson, Matthew H; Klette, Kevin L

2006-10-01

155

Gas chromatography-mass spectrometry confirmation of Cozart RapiScan saliva methadone and opiates tests.  

PubMed

The object of this study was to determine the sensitivity and specificity of the Cozart RapiScan onsite saliva test for methadone and opiates versus laboratory-based enzyme immunoassay (EIA) and gas chromatography-mass spectrometry (GC-MS) confirmation. Fifty saliva specimens were obtained from 28 volunteers among persons entering a substance abuse clinic. Specimens were tested onsite using the Cozart RapiScan Saliva test and Cozart RapiScan Reader. Specimens were retested by Cozart Microplate EIA assays on receipt at the laboratory and then frozen for later confirmation by GC-MS. For GC-MS, deuterated internal standards were added to specimen aliquots which were extracted using solid-phase columns at pH 6 and eluted with dichloromethane/isopropanol/ammonia (80:19:2). The dry residues were derivatized with PFOH and PFPA and dried, and the reconstituted extract was injected and quantitated by GC-MS. The Cozart RapiScan Methadone Saliva Assay was found to have a sensitivity and specificity of 100% +/- 12% versus GC-MS (2-ng/mL cutoff) and a sensitivity of 100% +/- 11% and a specificity of 95% +/- 2.4% versus the Microplate EIA for methadone (30-ng/mL cutoff). The Cozart RapiScan Saliva Opiate test had a sensitivity of 100% +/- 12% and a specificity of 92% +/- 3.2% versus GC-MS (2-ng/mL cutoff) and a sensitivity of 96% +/- 2.2% and specificity of 95% +/- 2.4% versus the Microplate EIA for opiates (30-ng/mL cutoff). PMID:11599594

Moore, L; Wicks, J; Spiehler, V; Holgate, R

2001-10-01

156

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

NASA Astrophysics Data System (ADS)

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, Dik; Brown, Stephen C.; Philp, R. Paul; Simoneit, Bernd R. T.

1980-07-01

157

NMR (Nuclear Magnetic Resonance) And GC/MS (Gas Chromatography/Mass Spectrometry) Investigation of the Saturate and Distillate Fractions from the Cerro Negro Heavy Petroleum Crude.  

National Technical Information Service (NTIS)

Six fractions of the Cerro Negro heavy petroleum crude have been evaluated using nuclear magnetic resonance spectroscopy (NMR) and gas chromatography/mass spectrometry (GC/MS). The fractions include four saturated hydrocarbon distillate fractions distilli...

D. A. Netzel F. D. Guffey

1987-01-01

158

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.

159

Authentication of organically and conventionally grown basils by gas chromatography/mass spectrometry chemical profiles.  

PubMed

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%, 93%, 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

2013-02-22

160

Simultaneous determination of urinary dialkylphosphate metabolites of organophosphorus pesticides using gas chromatography-mass spectrometry.  

PubMed

In this study, we developed a safe and sensitive method for the simultaneous determination of urinary dialkylphosphates (DAPs), metabolites of organophosphorus insecticides (OPs), including dimethylphosphate (DMP), diethylphosphate (DEP), dimethylthiophosphate (DMTP), and diethylthiophosphate (DETP), using a pentafluorobenzylbromide (PFBBr) derivatization and gas chromatography-mass spectrometry (GC-MS). Several parameters were investigated: pH on evaporation, reaction temperature and time for the derivatization, the use of an antioxidant for preventing oxidation, and a clean-up step. The pH was set at 6, adjusted with K2CO3, and the reaction temperature and time of derivatization were 80 degrees C and 30 min, respectively. Sodium disulfite was chosen as an antioxidant. The clean-up step was performed with a Florisil/PSE mini-column to remove the unreacted PFBBr and sample matrix. This established procedure markedly shortened the sample preparation time to only about 3 h, and completely inhibited the unwanted oxidization of dialkylthiophosphates. The limits of determination (LOD) were approximately 0.3 microg/L for DMP, and 0.1 microg/L for DEP, DMTP, and DETP in 5 mL of human urine. Within-series and between-day imprecision for the present method using pooled urine spiked with DAPs was less than 20.6% in the calibration range of 1-300 microg/L, and the mean recovery was 56.7-60.5% for DMP, 78.5-82.7% for DEP, 88.3-103.9% for DMTP, and 84.2-92.4% for DETP. This method detected geometric mean values of the urinary DAPs in Japanese with and without occupational exposure to OPs, 16.6 or 27.4 for DMP, 1.0 or 0.7 for DEP, 1.3 or 2.3 for DMTP, and 1.0 or 1.1 microg/L for DETP, respectively. The present method, which does not require special equipment except for GC-MS, is quick, safe, and sensitive enough to be adopted in routine biological monitoring of non-occupational as well as occupational exposure to OPs. PMID:16427368

Ueyama, Jun; Saito, Isao; Kamijima, Michihiro; Nakajima, Tamie; Gotoh, Masahiro; Suzuki, Takayoshi; Shibata, Eiji; Kondo, Takaaki; Takagi, Kenji; Miyamoto, Ken-ichi; Takamatsu, Junki; Hasegawa, Takaaki; Takagi, Kenzo

2006-01-19

161

Headspace solid-phase microextraction-gas chromatography-mass spectrometry characterization of propolis volatile compounds.  

PubMed

In this study, a novel and efficient method based on headspace solid-phase microextraction (HS-SPME), followed by gas chromatography-mass spectrometry (GC-MS), was developed for the analysis of propolis volatile compounds. The HS-SPME procedure, whose experimental parameters were properly optimized, was carried out using a 100 ?m polydimethylsiloxane (PDMS) fiber. The GC-MS analyses were performed on a HP-5 MS cross-linked 5% diphenyl-95% dimethyl polysiloxane capillary column (30 m × 0.25 mm I.D., 1.00 ?m film thickness), under programmed-temperature elution. Ninety-nine constituents were identified using this technique in the samples of raw propolis collected from different Italian regions. The main compounds detected include benzoic acid (0.87-30.13%) and its esters, such as benzyl benzoate (0.16-13.05%), benzyl salicylate (0.34-1.90%) and benzyl cinnamate (0.34-3.20%). Vanillin was detected in most of the samples analyzed in this study (0.07-5.44%). Another relevant class of volatile constituents is represented by sesquiterpene hydrocarbons, such as ?-cadinene (1.29-13.31%), ?-cadinene (1.36-8.85%) and ?-muurolene (0.78-6.59%), and oxygenated sesquiterpenes, such as ?-eudesmol (2.33-12.83%), T-cadinol (2.73-9.95%) and ?-cadinol (4.84-9.74%). Regarding monoterpene hydrocarbons, they were found to be present at low level in the samples analyzed in this study, with the exception of one sample from Southern Italy, where ?-pinene was the most abundant constituent (13.19%). The results obtained by HS-SPME-GC-MS were also compared with those of hydrodistillation (HD) coupled with GC-MS. The HS-SPME-GC-MS method developed in this study allowed us to determine the chemical fingerprint of propolis volatile constituents, thus providing a new and reliable tool for the complete characterization of this biologically active apiary product. PMID:23807002

Pellati, Federica; Prencipe, Francesco Pio; Benvenuti, Stefania

2013-06-03

162

The use of stable isotopes and gas chromatography/mass spectrometry in the identification of steroid metabolites in the equine  

SciTech Connect

Stable isotope gas chromatography/mass spectrometry has been used successfully in the elucidation of structures of urinary steroid metabolites in the horse and in the identification of metabolites isolated from in vivo perfusion and in vitro incubation studies using equine tissue preparations. Deuterium-labeled steroids, testosterone, dehydroepiandrosterone, and 5-androstene-3 beta,17 beta-diol have been synthesized by base-catalyzed isotope exchange methods and the products characterized by gas chromatography/mass spectrometry. (16,16(-2)H2)Dehydroepiandrosterone (plus radiolabeled dehydroepiandrosterone) was perfused into a testicular artery of a pony stallion and was shown to be metabolized into 2H2-labeled testosterone, 4-androstenedione, isomers of 5-androstene-3,17-diol, 19-hydroxytestosterone, and 19-hydroxy-4-androstenedione. In further studies, equine testicular minces have been incubated with 2H2-labeled and radiolabeled dehydroepiandrosterone and 5-androstene-3 beta, 17 beta-diol. The metabolites, whose identity was confirmed by stable isotope gas chromatography/mass spectrometry, proved the interconversion of the two substrates, as well as formation of testosterone and 4-androstenedione. The aromatization of dehydroepiandrosterone was also confirmed, together with the formation of an isomer of 5(10)-estrene-3,17-diol from both substrates showing 19-demethylation without concomitant aromatization. In studies of the feto-placental unit, the allantochorion was shown to aromatize (2H5)testosterone to (2H4)estradiol, the loss of one 2H from the substrate being consistent with aromatization of the A ring. The formation of 6-hydroxyestradiol was also confirmed in this study. The same technique has been valuable in determining the structure of two metabolites of nandrolone isolated from horse urine.

Houghton, E.; Dumasia, M.C.; Teale, P.; Smith, S.J.; Cox, J.; Marshall, D.; Gower, D.B. (Horseracing Forensic Laboratory, Newmarket, Suffolk (England))

1990-10-01

163

Thermal desorption-gas chromatography-mass spectrometry method to determine phthalate and organophosphate esters from air samples.  

PubMed

A method based on thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) has been developed to determine four organophosphate esters, seven phthalate esters, and bis(2-ethylhexyl) adipate in the gas phase from harbour and urban air samples. The method involves the sampling of 1.5L of air in a Tenax TA sorbent tube followed by thermal desorption (using a Tenax TA cryogenic trap) coupled to gas chromatography-mass spectrometry. The repeatability of the method expressed as %RSD (n=3) is less than 15% and the MQLs are between 0.007?gm(-3) (DMP, TBP, BBP, TPP and DnOP) and 6.7?gm(-3) (DEHP). The method was successfully applied in two areas (urban and harbour) testing two and three points in each one, respectively. Some of these compounds were found in both urban and harbour samples. Di-(2-ethylhexyl)phthalate was the most abundant compound found in both areas at concentration levels between 6.7?gm(-3) and 136.4?gm(-3). This study demonstrates that thermal desorption is an efficient method for the determination of these semi-volatile compounds in the gas phase fraction of air samples. PMID:23859797

Aragón, M; Borrull, F; Marcé, R M

2013-06-19

164

Metabolism of isometheptene in human urine and analysis by gas chromatography-mass spectrometry in doping control.  

PubMed

A study of the metabolism of isometheptene, an antispasmodic drug, in man and comparison with heptaminol metabolism, is presented in this paper. Isometheptene and two metabolites were detected in human urine after oral administration of a tablet containing isometheptene mucate. The urine level of the parent drug, which is excreted during the first 24 h, was determined using gas chromatography-mass spectrometry, after alkaline extraction with organic solvent. A minor metabolite of isometheptene was converted to heptaminol in vitro under the acidic hydrolysis conditions used for the screening procedure of stimulants and narcotics in doping control analysis. PMID:16242387

Lyris, Emmanouil; Tsiakatouras, George; Angelis, Yiannis; Koupparis, Michael; Spyridaki, Maria-Helen; Georgakopoulos, Costas

2005-10-19

165

Electron ionization gas chromatography-mass spectrometric determination of residues of thirteen pyrethroid insecticides in whole blood.  

PubMed

A new rapid and sensitive electron ionization gas chromatography-mass spectrometry method in selective ion monitoring mode (SIM) was developed for the determination of l3 synthetic pyrethroid insecticide molecules and their stereo isomers in whole blood. The pyrethroid insecticides investigated are allethrin, bifenthrin, cypermethrin, cyphonothrin, cyfluthrin, lambda-cyhalothrin, deltamethrin, fenvalerate, fenpropathrin, imiprothrin, permethrin, prallethrin and transfluthrin. The residues of pyrethroids are extracted from the whole blood using hexane and acetone mixture (80 + 20%) as solvent. All the pyrethroid residues were separated by using a gas chromatography-mass spectrometry operated in electron ionization mode and quantified in selective ion monitoring mode. The method can detect the residues of different pyrethroids down to the level 0.05-2 ng/ml. Recovery experiments conducted in whole blood samples at the fortification level 1-1000 ng/ml showed 91-103% recovery. The applications of the analytical method for the determination of pyrethroid residues in real samples were tested by analyzing 45 human blood samples collected from the population exposed continuously to different pyrethroid based formulations. The results are confirmed by spiking the known quantity of pyrethroids and subsequently their positive detection. PMID:15018801

Ramesh, Atmakuru; Ravi, Perumal Elumalai

2004-04-01

166

Characterization of complex hydrocarbons in cigarette smoke condensate by gas chromatography–mass spectrometry and comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry  

Microsoft Academic Search

Gas chromatography–mass spectrometry with electron ionization and positive-ion chemical ionization and comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC × GC–TOF-MS) were applied for the characterization of the chemical composition of complex hydrocarbons in the non-polar neutral fraction of cigarette smoke condensates. Automated data processing by TOF-MS software combined with structured chromatograms and manual review of library hits were used to

Xin Lu; Mingyue Zhao; Hongwei Kong; Junlan Cai; Jianfang Wu; Ming Wu; Ruixiang Hua; Jianfu Liu; Guowang Xu

2004-01-01

167

Determination of oxygenated volatile organic compounds in ambient air using canister collection-gas chromatography/mass spectrometry.  

PubMed

This research attempts to establish a method to measure 11 kinds of oxygenated volatile organic compound (OVOC) in ambient air by using the canister collection-gas chromatography/mass spectrometry (GC/MS) method. Since several compounds such as acetone exhibited high blank concentrations due to their laboratory use, stringent quality control was conducted for the VOC-free added water and the VOC-free nitrogen gas. In order to prevent the decline of recovery rates due to lack of sufficient relative humidity, it is necessary to add VOC-free water when pressurizing and diluting the air samples. Thus, all the target compounds in ambient air were obtained from the canisters at high recovery rates without significant contamination. Furthermore, the canister collection-GC/MS method makes it possible to apply simultaneous air monitoring of OVOCs as well as volatile hazardous air pollutants without additional sampling. PMID:17690433

Hoshi, Jun-Ya; Higuchi, Masato; Sasaki, Yuko; Korenaga, Takashi

2007-08-01

168

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

2013-04-09

169

Comparison of purification procedures for the isolation and detection of anabolic residues in faeces using gas chromatography-mass spectrometry.  

PubMed

Within several regional field laboratories and the national reference laboratory a harmonised methodology for the analysis of anabolic residues in faecal samples was developed. The method consists of a liquid-liquid and a solid-phase extraction step, followed by a high-performance liquid chromatography purification step. Using gas chromatography-mass spectrometry, currently illegally used anabolic steroids can be detected in faeces at the ppb level. Within this context acidification, followed by centrifugation under cooling, allows efficient, practical and rapid defatting of faecal samples. Furthermore, a combination of a silica and an aminopropyl solid-phase extraction column was found to give the best results as regards the sample purification process. PMID:10435311

Hamoir, T; Courtheyn, D; De Brabander, H; Delahaut, P; Leyssens, L; Pottie, G

1998-12-01

170

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

171

Determination of Se4+ in drinkable water by solid-phase microextraction and gas chromatography/mass spectrometry.  

PubMed

A method was developed for the selective determination of Se4+ in drinkable water by solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS). Se4+ was selectively derivatized to ethane, 1,1'-selenobis by reaction with sodium tetraethylborate, extracted by the SPME fiber, and determined by GC/MS. Both headspace (HS)-SPME and direct SPME were studied. The method requires only a few milliliters of sample and 20 min for completion. At 2.0 microg/L concentration, the relative standard deviation was 10.1% for HS-SPME and 9.1% for direct SPME. For HS-SPME, the theoretical detection limit was 81 ng/L and 166 ng/L for direct SPME. The recovery rate was 95%. The method was used to determine Se4+ in 10 tap water samples. PMID:11048848

Guidotti, M

172

Analysis of tryptamine at the femtomole level in tissue using negative ion chemical ionization gas chromatography-mass spectrometry.  

PubMed

An ultra sensitive method for the detection of tryptamine, an endogenous amine in mammalian neuronal systems, at the femtomole level has been developed using negative chemical ionization gas chromatography-mass spectrometry (NCI-GC-MS). The amine is converted into a perfluorinated spirocyclic derivative, e.g. 1-pentafluoro-2-methylenepyrrolidine-3-spiro-3'-(3H-indole) which is detected using selected-ion monitoring of the (M-2HF) ions of the endogenous and deuterated internal standard compounds. Two mass spectrometers were compared; they gave minimum detectable quantities from tissue samples of 40 pg (VG-7070F) and 0.9 pg (VG-70S) respectively. These detection levels are approximately 5-200 times lower than have been obtained by previous MS methods. PMID:3403664

Durden, D A; Boulton, A A

1988-05-25

173

Rapid multiresidue determination for currently used pesticides in agricultural drainage waters and soils using gas chromatography-mass spectrometry.  

PubMed

An efficient and sensitive method for simultaneous determination of 38 pesticides in agricultural drainage waters and soils has been developed and validated. Water samples were extracted using solid-phase extraction with C18 cartridges while solid samples (suspended particle matter and soil) were extracted by using the quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction method. The target pesticides were analyzed by using gas chromatography-mass spectrometry with electron impact ionization. The proposed method allowed a simultaneous determination and confirmation of a large number of pesticides in agricultural drainage waters, suspended particle matters and soils/sediments with a good reproducibility and low detection limits. The developed method was applied to a survey of pesticides in a vegetable growing area of Guangzhou, China. The pesticides commonly found in the area were butachlor, carbofuran, dichlorvos, fipronil, isocarbophos and pyridaben. PMID:20390945

Yang, Xiao-Bing; Ying, Guang-Guo; Kookana, Rai S

2010-02-01

174

Fatty acid composition of wild mushroom species of order Agaricales--examination by gas chromatography-mass spectrometry and chemometrics.  

PubMed

Applying gas chromatography-mass spectrometry of 4,4-dimethyloxazoline fatty acid derivatives, the fatty acid composition of 15 mushroom species belonging to 9 genera and 5 families of order Agaricales growing in Bulgaria is determined. The structure of 31 fatty acids (not all present in each species) is unambiguously elucidated, with linoleic, oleic and palmitic acids being the main components (ranging between 70.9% (Marasmius oreades) and 91.2% (Endoptychum agaricoides)). A group of three hexadecenoic positionally isomeric fatty acids, 6-, 9- and 11-16:1, appeared to be characteristic components of the examined species. By applying chemometrics it was possible to show that the fatty acid composition closely reflects the classification of the species. PMID:23168239

Marekov, Ilko; Momchilova, Svetlana; Grung, Bjørn; Nikolova-Damyanova, Boryana

2012-10-29

175

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

PubMed

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

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

2013-08-21

176

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

PubMed

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

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

2009-05-21

177

Multiresidue determination of pesticides in agricultural products by gas chromatography/mass spectrometry with large volume injection.  

PubMed

A method is described for the rapid determination of pesticide residues in agricultural products. Pesticides were extracted from samples with acetonitrile. To remove pigments and fatty acids, an aliquot of the extract was cleaned up by a minicolumn that was packed both with graphitized carbon black and primary secondary amine. Analysis was performed by gas chromatography/ mass spectrometry with programmable temperature vaporizer-based large volume injection using a liner packed with phenylmethylsilicone chemically bonded silica. The method was evaluated for 114 pesticides by spiking into tomato, spinach, Japanese pear, grape, and brown rice at various concentrations of each pesticide (0.02-0.4 microg/g). The method, which gave good recovery (>60%) for 108 pesticides, is characterized by high cleanup efficiency and short cleanup time, and is useful as a rapid screening analysis. PMID:15675447

Saito, Yukio; Kodama, Shuji; Matsunaga, Akinobu; Yamamoto, Atsushi

178

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

179

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

NASA Astrophysics Data System (ADS)

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.

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

180

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

PubMed

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

Sarkissian, Garry

2007-09-01

181

Quantitation of trimethyl amine by headspace gas chromatography-mass spectrometry using a base-modified column.  

PubMed

Headspace gas chromatography-mass spectrometry (GC-MS) has been successfully applied to the analysis of the highly volatile species trimethyl amine (TMA). TMA quantitation in fiberglass insulation resins (ultimately used by the automotive and building products industries) is of interest because of its highly odoriferous nature. The release of TMA from fiberglass insulation products is the principal component responsible for the "fishy" odor encountered in automobiles. Currently, the industry standard for the analysis of TMA involves injecting an aqueous insulation extract into the GC-MS equipped with a polyethylene glycol column. Several problems inherent in this analysis prohibit consistent performance and enhance the possibility for wide variations in the quantitative results. This article reports the development of a new approach to the quantitation of TMA from fiberglass insulation between the levels of 1 and 150 ppm. PMID:12137206

Bir, David; Tutin, Kim

2002-07-01

182

Biocatalytic Lactone Generation in Genetically Engineered Escherichia coli and Identification of Products by Gas Chromatography-Mass Spectroscopy  

NASA Astrophysics Data System (ADS)

Genetically altered Escherichia coli are used as biocatalysts to produce optically pure lactones from a variety of cyclic ketones as a biotechnology experiment for a biochemistry laboratory. The genetically engineered E. coli bacteria express large amounts of the enzyme cyclohexanone monooxygenase and are therefor capable of converting a variety of ketones into optically pure lactones. Separation by organic extraction and analysis by thin layer chromatography and gas chromatography-mass spectroscopy allows for the direct identification of products. Yield calculations and evaluation of the cost effectiveness of various substrates give students an opportunity to make recommendations and model industrial decision-making. Evaluation of the synthetic process for its environmental impact allows students to consider problems of cost versus environmental concerns. Use of bacterial biocatalysts offers chemistry students an opportunity to work with microorganisms and directly see the utility of genetically altered bacteria for synthetic chemistry.

Slawson, Chad; Stewart, Jon; Potter, Robert

2001-11-01

183

Identification of a pharmaceutical packaging off-odor using solid phase microextraction gas chromatography/mass spectrometry.  

PubMed

The use of a solid phase microextraction (SPME) sampling technique, in conjunction with gas chromatography/mass spectrometry (GC/MS) analysis, to identify an off-odor in a heat-stressed pharmaceutical packaging material is described. The ability of the commercially available polydimethylsiloxane (PDMS) coated microfiber to concentrate a trace volatile compound of interest enabled identification of the odor compound of interest. Despite being present at levels that defied detection using conventional headspace sampling techniques, ethyl-2-mercaptoacetate was determined to be the compound responsible for the offending odor. Formation of the thioester resulted from an unanticipated reaction (either esterification or transesterification) between a common residual solvent (ethanol), present in a commonly used pharmaceutical tablet dispersant, and low-level amounts of reactants or synthetic intermediates of an FDA-approved polyvinyl chloride (PVC)-resin thermal stabilizing agent. PMID:11377016

Sides, S L; Polowy, K B; Thornquest, A D; Burinsky, D J

2001-06-01

184

Rapid gas chromatography-mass spectrometry screening method for human pharmaceuticals, hormones, antioxidants and plasticizers in water.  

PubMed

A rapid gas chromatography-mass spectrometry (GC-MS) method was developed and validated allowing quantification at the ng/l level of 19 analytes in water including human pharmaceuticals, hormones, antioxidants and a plasticizer. On-line continuous liquid-liquid extraction with dichloromethane of 10-401 unfiltered water samples was used to achieve a 10000-40000-fold concentration factor. No sample cleanup or derivatization was required. Recoveries ranged from 57 to 120%. Application of the method to water recycling plant effluent demonstrated the presence of nearly all targeted compounds at ng/l to microgram/l levels. Screening for nontarget compounds in the treated effluent samples indicated the method could be readily extended to include additional analytes. PMID:15043002

Soliman, Mary A; Pedersen, Joel A; Suffet, I H Mel

2004-03-12

185

Analyzing salvia divinorum and its active ingredient salvinorin a utilizing thin layer chromatography and gas chromatography/mass spectrometry.  

PubMed

In recent years, Salvia divinorum has become a major focus by state legislatures throughout the United States looking to prohibit the sale of the psychoactive plant. After researching testing procedures presented in the literature and those employed by crime laboratories throughout the country, it was decided that thin layer chromatography (TLC) and gas chromatography/mass spectrometry (GC/MS) were the methods to use to analyze plant material for salvinorin A. With TLC, salvinorin A was detected from extracted plant material and was easily distinguishable from 13 other Salvia species as well as Cannabis sativa L. (marijuana). When using GC/MS, salvinorin A was best extracted from plant material with chloroform at ambient temperature when using a nonpolar solvent and acetone at ambient temperature when using a polar solvent. By utilizing these techniques, criminalists are now able to confirm the presence of salvinorin A in a submitted plant material suspected to be Salvia divinorum. PMID:19298461

Jermain, John D; Evans, Hiram K

2009-02-27

186

[Rapid determination of alkaloids in tobacco using gas chromatography-mass spectrometry with full scan-selected ion monitoring mode].  

PubMed

Simultaneous full scan-selected ion monitoring mode (Scan-SIM) is a new improvement method of data acquisition of gas chromatography-mass spectrometry (GC-MS). A method of determing alkaloids in tobacco was established by GC-MS with Scan-SIM. Nicotine, nornicotine, anabasine and anatabine were determined with scan mode, and myosmine, nicotyrine, 2,3'-bipyridyl and cotinine were determined with SIM mode. The average recoveries of alkaloids ranged from 94.8% to 98.8%, and the relative standard deviations were less than 6.0% (n = 5). Therefore, it is a simple, rapid, accurate method. Tobacco samples picked in different years were determined using this method, and the results were satisfactory. PMID:18724666

Wang, Baoxing; Yang, Shihua; Hou, Ying; Zeng, Xiaoying; Wu, Yi; Xu, Guowang

2008-05-01

187

RUGGEDNESS AND OTHER PERFORMANCE CHARACTERISTICS OF LOW-PRESSURE GAS CHROMATOGRAPHY-MASS SPECTROMETRY FOR THE FAST ANALYSIS OF MULTIPLE PESTICIDE RESIDUES IN FOOD CROPS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Low-pressure gas chromatography-mass spectrometry (LP-GC-MS) using a quadrupole MS instrument was further optimized and evaluated for the fast analysis of multiple pesticide residues in food crops. Performance of two different LP-GC-MS column configurations was compared in various experiments, incl...

188

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

Microsoft Academic Search

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

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

2006-01-01

189

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

190

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

191

Comparison of gas chromatography-mass spectrometry, radioimmunoassay and bioassay for the quantification of gibberellin A 9 in norway spruce ( Picea abies (L.) Karst.)  

Microsoft Academic Search

Quantitative estimates of gibberellin A9 in Norway spruce extracts obtained by gas chromatography-mass spectrometry, radioimmunoassay (RIA_ and bioassay were compared after successive purifications of the extracts. The extracts were assayed in several dilutions with and without the addition of standard gibberellin A9, thus showing the effect of extract components on the response of the assays. Radioimmunoassay produced estimates comparable to

Per Christer Odén; Elmar W. Weiler; Ludger Schwenen; Jan E. Graebe

1987-01-01

192

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

EPA Science Inventory

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

193

Two procedures for suppressing interference from inorganic pigments in the analysis by gas chromatography–mass spectrometry of proteinaceous binders in paintings  

Microsoft Academic Search

Two methods for suppressing the interference of inorganic pigments in the determination of amino acids in hydrolysates of wall painting samples by gas chromatography–mass spectrometry are described. One is based on the extraction of proteinaceous matter from the sample by a 2.5 M ammonia solution prior to the hydrolysis step, and the other on the elimination of inorganic ions from

Maria Perla Colombini; Francesca Modugno; Ambrogio Giacomelli

1999-01-01

194

Components Detected by Means of SolidPhase Microextraction and Gas Chromatography\\/Mass Spectrometry in the Headspace of Artisan Fresh Goat Cheese Smoked by Traditional Methods  

Microsoft Academic Search

The study of the headspace components of fresh smoked goat cheese, was carried out by means of solid- phase microextraction using a polyacrylate fiber fol- lowed by gas chromatography\\/mass spectrometry. The samples studied were six artisan Palmero cheeses man- ufactured following traditional methods and smoked using pine needles. The cheese regions studied were exterior, interior, and a cross section. In

M. D. Guillén; M. L. Ibargoitia; P. Sopelana; G. Palencia; M. Fresno

2004-01-01

195

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

PubMed Central

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

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

1990-01-01

196

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

PubMed

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

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

1990-05-01

197

A laboratory pilot for in situ analysis of refractory organic matter in Martian soil by gas chromatography mass spectrometry  

NASA Astrophysics Data System (ADS)

The “Sample Analysis at Mars” project (SAM) is a multi purpose space experiment devoted to the in situ analysis of the Martian environment. It is designed to run multiple analyses on gas or solid samples, and eventually liquids, and is proposed to be part of the scientific payload of the future NASA Mars Science Laboratory 2009 (MSL 2009). One of its main objectives is to discover traces of a past or present life on the planet. Here is presented the laboratory pilot system for automated analysis of possibly refractory organic matter in Martian soil samples, which corresponds to a part of the Chemical Separation and Processing Laboratory of SAM experiment. It is a one-pot process performing, in a row, extraction, derivatization and transfer of the organic molecules to a gas chromatography mass spectrometer for analysis. We have shown that such a system is able to detect 10 pmol of refractive material from a 100 mg sample of Atacama desert, which is a good Martian analogue for organics analysis. This pilot can handle and allow the analysis of a wide range of molecules, including carboxylic and amino acids, which are of utmost interest for the goal which is aimed. Further on, such a system is universal, and could be taken as a good start for any future in situ exploratory space mission.

Meunier, Damein; Sternberg, Robert; Mettetal, Franck; Buch, Arnaud; Coscia, David; Szopa, Cyril; Rodier, Claude; Coll, Patrice; Cabanec, Michael; Raulin, François

198

Determination of the cyanide metabolite 2-aminothiazoline-4-carboxylic acid in urine and plasma by gas chromatography-mass spectrometry.  

PubMed

The cyanide metabolite 2-aminothiazoline-4-carboxylic acid (ATCA) is a promising biomarker for cyanide exposure because of its stability and the limitations of direct determination of cyanide and more abundant cyanide metabolites. A simple, sensitive, and specific method based on derivatization and subsequent gas chromatography-mass spectrometry (GC-MS) analysis was developed for the identification and quantification of ATCA in synthetic urine and swine plasma. The urine and plasma samples were spiked with an internal standard (ATCA-d(2)), diluted, and acidified. The resulting solution was subjected to solid phase extraction on a mixed-mode cation exchange column. After elution and evaporation of the solvent, a silylating agent was used to derivatize the ATCA. Quantification of the derivatized ATCA was accomplished on a gas chromatograph with a mass selective detector. The current method produced a coefficient of variation of less than 6% (intra- and interassay) for two sets of quality control (QC) standards and a detection limit of 25 ng/ml. The applicability of the method was evaluated by determination of elevated levels of ATCA in human urine of smokers in relation to non-smokers for both males and females. PMID:15833287

Logue, Brian A; Kirschten, Nicholas P; Petrikovics, Ilona; Moser, Matthew A; Rockwood, Gary A; Baskin, Steven I

2005-05-25

199

[Development and validation of an assay method of the paraphenylene diamine by gas chromatography-mass spectrometry].  

PubMed

Paraphenylenediamine is an aromatic amine used as a hair dye; it is responsible for poisoning characterized by respiratory distress involving life-threatening. The objective of this work is the development and validation of an assay of para-phenylenediamine in the whole blood. The method is based on the determination of paraphenylene diamine in whole blood by gas chromatography-mass spectrometry after liquid-liquid extraction and derivatization. The validation protocol has included the study of the recovery factor of extraction, the measurement range, accurency, repetability and intermediate precision. The calibration curve was linear between 98 and 1350 ?g/L (r = 0.999), the limit of detection and quantification were 37 ?g/L and 63 ?g/L respectively. The accuracy were 94.7%. Coefficients of variation were (2.3/6.8/9.7%) for repeatability and (4.4/8.7/9.8%) for intermediate precision. The method is suitable for quantification of PPD in acute poisoning situations. A method for the determination of the paraphenylene diamine in the whole blood by gas chromatography coupled to mass spectrometry was developed. The validation of the method showed good linearity, good accuracy and low limit of quantification. PMID:23207813

Bousliman, Yassir; Eljaoudi, Rachid; Elcadi, Mina Ait; Basset, Thiery; Gay-Montchamp, Jean-Pierre; Zeggwagh, Amine Ali; Bouklouze, Abdelaziz; Cherrah, Yahia; Ollagnier, Michel

200

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 r²=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

2011-12-26

201

Chemotaxonomic differentiation of legionellae by detection and characterization of aminodideoxyhexoses and other unique sugars using gas chromatography-mass spectrometry.  

PubMed Central

Legionellae have been differentiated previously by analyzing their carbohydrate contents by gas chromatography with flame ionization detection. In the present study, total ion mode gas chromatography-mass spectrometry (GC-MS) was used to detect a number of unusual sugars, including one that is structurally related to O-methyldideoxyheptoses. Increased sensitivity and selectivity for carbohydrate detection was achieved by selected ion-monitoring GC-MS. Two of the uncommon sugars previously discovered in the legionellae (X1 and X2) were identified as quinovosamine and fucosamine, respectively. Legionella pneumophila contained rhamnose and quinovosamine but not the quinovosamine isomer fucosamine. Tatlockia micdadei and Legionella maceachernii contained large amounts of rhamnose, fucose, and fucosamine but not quinovosamine. These two species were the only legionellae studied that contained another unusual sugar that is referred to as X3, pending determination of its structure. Fluoribacter dumoffi, Fluoribacter bozemanae, and Legionella anisa were varied in their carbohydrate contents, both within and between species, but could be distinguished from L. pneumophila and the T. micdadei and L. maceachernii group. Fluoribacter gormanii was unique among the legionellae in that it lacked both quinovosamine and fucosamine. Legionella jordanis contained other unusual carbohydrates in addition to quinovosamine. GC-MS may have wide application in the differentiation of bacterial species.

Fox, A; Rogers, J C; Fox, K F; Schnitzer, G; Morgan, S L; Brown, A; Aono, R

1990-01-01

202

A multiresidue method for the determination 234 pesticides in Korean herbs using gas chromatography mass spectrometry  

Microsoft Academic Search

A rapid, specific and sensitive multiresidue method based on dispersive solid phase extraction sample preparation and gas chromatography with the mass spectrometric detection for the analysis of 234 pesticides in Korean herbs (Acanthopanax senticosus, Morus alba L., Hovenia dulcis) has been developed. Method recoveries were found to be between 62 and 119% with relative standard deviation lower than 21% for

Thanh Dong Nguyen; Kyung Jun Lee; Myoung Hee Lee; Gae Ho Lee

2010-01-01

203

Using gas chromatography\\/mass spectroscopy fingerprint analyses to document process and progress of oil degradation  

Microsoft Academic Search

One of the challenges in testing the effectiveness of bioremediation products is the lack of a standardized testing protocol. One requirement of any such evaluation is baseline and benchmark analyses of the oil and its degradation processes. The method described uses high resolution gas chromatography maw spectroscopy (GC\\/MS). This method has been adapted from oil fingerprinting techniques used by our

D. E. Roques; E. B. Overton; C. B. Henry

1994-01-01

204

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...

205

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

EPA Science Inventory

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

206

Characterization of Low Temperature Carbonization Products of Neyveli Lignite by Gas Chromatography–Mass Spectroscopy  

Microsoft Academic Search

Neyveli lignites of Indian origin were subjected to low temperature carbonization (LTC) at 600°C to collect tar and middle oil boiling at 200°C. Liquid–liquid extraction of these products has yielded asphalts, phenols, acids, bases, waxes, and neutral oils. Each fraction was analysed by gas liquid chromatography and the constituents were characterized by elucidating the structural composition using mass spectrometry. This

R. Nageswara Rao; B. Krishnamacharyulu

2005-01-01

207

Estimation of BTEX in groundwater by using gas chromatography–mass spectrometry  

Microsoft Academic Search

Advanced analytical modern technology such as coupling a gas chromatography to a mass spectrometric technique provides sufficient information to the environmental and analytical chemists to identify the presence of a variety of components of the specific volatile organic product, determine the degree of the product weathering and in some instances estimate the age of the product as well in the

M. A. Kamal; P. Klein

2010-01-01

208

Optimization of large-volume programmed-temperature vaporizing injection for gas chromatography—Mass spectrometry. Analysis of narcotics and stimulants in biological fluids with reduced sample consumption  

Microsoft Academic Search

Summary  The objective of this study was to evaluate a programmed-temperature vaporizing injectionbased method for gas chromatographic-mass\\u000a spectrometric determination of narcotics and stimulants in biological fluids (blood, saliva, etc) with a considerable reduction\\u000a in sample consumption. Suitable operating conditions for gas chromatographymass spectrometry with large-volume injection\\u000a were determined and sample preparation was slightly adapted to the micro method. The method

J. Teske; K. Putzbach; W. Engewald; W. J. Kleernann; R. K. Müller

2003-01-01

209

Gas chromatography-mass spectrometry coupled with pseudo-Sadtler retention indices, for the identification of components in the essential oil of Curcuma longa L  

Microsoft Academic Search

Gas chromatography-mass spectrometry was applied to the cyclohexane extract of Curcuma longa L. The chromatographic conditions generated retention indices very close i.e., greater than 99.9%, to those reported for structures in the Sadtler Standard Gas Chromatography Retention Index Library. In addition to the extensively reported sesquiterpene ketones, this essential oil extract contained a series of saturated and unsaturated fatty acids.

R. Richmond; E. Pombo-Villar

1997-01-01

210

Qualitative and quantitative analysis of carbohydrates in green juices (wild mix grass and alfalfa) from a green biorefinery by gas chromatography \\/ mass spectrometry  

Microsoft Academic Search

Green juices from biorefinery original raw material (wild mix grass and alfalfa after wet fractionation and protein separation)\\u000a have been investigated by gas chromatography\\/mass spectrometry. The carbohydrates, involved in the green juices, were derivatized\\u000a and identified by both their retention times in the gas chromatogram and EI mass spectra compared to those of pure reference\\u000a compounds. Additionally, chemical ionization mass

Ines Starke; Anja Holzberger; Birgit Kamm; Erich Kleinpeter

2000-01-01

211

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

Microsoft Academic Search

A new, simple and selective method for the analysis of 5-hydroxymethylfurfural (HMF) in foods by gas chromatography coupled to mass spectrometry (GC–MS) is proposed. Several derivatising procedures based on the formation of an HMF silylated derivative using different reagents were studied. Among the derivatising reagents examined, N,O-bis-trimethylsilyltrifluoroacetamide (BSTFA) provided the best derivatisation yield. Sample clean-up was also optimised, using either

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

2006-01-01

212

Heat-map visualization of gas chromatography-mass spectrometry based quantitative signatures on steroid metabolism  

Microsoft Academic Search

Abnormalities in steroid hormones are responsible for the development and prevention of endocrine diseases. Due to their biochemical\\u000a roles in endocrine system, the quantitative evaluation of steroid hormones is needed to elucidate altered expression of steroids.\\u000a Gas chromatographic-mass spectrometric (GC-MS) profiling of 70 urinary steroids, containing 22 androgens, 18 estrogens, 15\\u000a corticoids, 13 progestins, and 2 sterols, were validated and

Ju-Yeon Moon; Hyun-Jin Jung; Myeong Hee Moon; Bong Chul Chung; Man Ho Choi

2009-01-01

213

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

Microsoft Academic Search

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

Dinesh K. Barupal; Tobias Kind; Shankar L. Kothari; Do Yup Lee; Oliver Fiehn

2010-01-01

214

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

PubMed

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

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

2013-02-01

215

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 ngL(-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?gL(-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

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

2013-07-31

216

Speciation of butyltin compounds in marine sediments with headspace solid phase microextraction and gas chromatography mass spectrometry.  

PubMed

A method for the determination of organotin compounds (monobutyl = MBT, dibutyl = DBT, and tributyltin = TBT) in marine sediments by headspace Solid Phase Microextraction (SPME) has been developed. The analytical procedure involved 1) extraction of TBT, DBT and MBT from sediments with HCl and methanol mixture, 2) in situ derivatization with sodium tetraethylborate and 3) headspace SPME extraction using a fiber coated with poly(dimethylsiloxane). The derivatized organotin compounds were desorbed into the splitless injector and simultaneously analyzed by gas chromatography - mass spectrometry. The analytical method was optimized with respect to derivatization reaction and extraction conditions. The detection limits obtained for MBT, DBT and TBT ranged from 730 to 969 pg/g as Sn dry weight. Linear calibration curves were obtained for all analytes in the range of 30-1000 ng/L as Sn. Analysis of a standard reference sediment (CRM 462) demonstrates the suitability of this method for the determination of butyltin compounds in marine sediments. The application to the determination of TBT, DBT and MBT in a coastal marine sediment is shown. PMID:11336336

Cardellicchio, N; Giandomenico, S; Decataldo, A; Di Leo, A

2001-03-01

217

Determination of organotin compounds in-water by headspace solid phase microextraction with gas chromatography-mass spectrometry.  

PubMed

This investigation evaluates headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) to determine trace levels of organotins in water. The organotins were derivatized in situ with sodium tetraethylborate and adsorbed on a poly(dimethysiloxane) (PDMS)-coated fused silica fiber. The SPME experimental procedures to extract organotins in water were at pH 5, with extraction and derivatization simultaneously at 45 degrees C for 30 min in a 2% sodium tetraethylborate solution and a sample solution volume in the ratio of 1:1, and desorption in the splitless injection port of the GC at 260 degrees C for 2 min. Detection limits are determined to be in the low ng/L range. According to the analysis, the linearity range is from 10 to 10,000 ng/L with R.S.D. values below 12% except triphenyltin (24%). The proposed method was tested by analyzing surface seawater from the harbors on the Taiwanese coast for organotins residues. Some organotins studied were detected in the analyzed samples. Results of this study demonstrate the adequacy of the headspace SPME-GC-MS method for analyzing organotins in sea water samples. PMID:15729814

Chou, Chi-Chi; Lee, Maw-Rong

2005-01-28

218

Identification and quantification of the osmodiuretic mannitol in urine for sports drug testing using gas chromatography-mass spectrometry.  

PubMed

The osmodiuretic mannitol can be potentially misused in sports, owing to its urine diluting effect and the possibility to decrease bodyweight. To reveal a doping offence, resulting urinary mannitol concentrations after a prohibited intravenous application and a permitted oral intake have to be differentiated. Therefore, a reliable gas chromatography-mass spectrometry (GC-MS) method was established based on peracetyl derivatives of the analytes. All possible hexitols (allitol, galactitol, iditol, altritols, sorbitol and mannitol) that can occur in human urine were separated and identified on a phenyl-methylpolysiloxane column (HP-5MS) within 10.75 min, and the method demonstrated its capability for quantification purposes. The lower limit of detection and lower limit of quantification were estimated at 0.9 microg mL(-1) and 2.4 microg mL(-1), respectively, and the assay was validated for mannitol and sorbitol regarding the parameters specificity, linearity, intra- (<10%) and inter-day precision (<15%) and accuracy (92-102%). To investigate urinary mannitol concentrations after oral intake the method was applied to an excretion study, providing a mean urinary excretion of mannitol of 19.5%. Comparison of theoretically expected urinary levels after a common therapeutic dose of mannitol and preliminary results on physiological urinary mannitol levels were promising, regarding a threshold level for mannitol that can be utilised for doping control purposes. PMID:18708692

Guddat, Sven; Thevis, Mario; Schänzer, Wilhelm

2008-01-01

219

Ionic liquid coated magnetic nanoparticles for the gas chromatography/mass spectrometric determination of polycyclic aromatic hydrocarbons in waters.  

PubMed

In this paper, ionic liquid coated magnetic nanoparticles (IL-MNPs) have been prepared by covalent immobilization. The as-synthesized MNPs have been successfully used as sorbent for the extraction of polycyclic aromatic hydrocarbons (PAHs) from water samples, the analytes being finally determined by gas chromatography/mass spectrometry. The influence of several experimental variables (including the ionic strength, amount of MNPs, sample volume, agitation time and desorption solvent) has been considered in depth in the optimization process. The developed method, which has been analytically characterized under its optimal operation conditions, allows the detection of the analytes in the samples with method detection limits in the range from 0.04?gL(-1) (fluoranthene) to 1.11?gL(-1) (indeno(1,2,3-cd)pyrene). The repeatability of the method, expressed as relative standard deviation (RSD, n=7), varies between 4.0% (benzo[b]fluoranthene) and 8.9% (acenaphthene), while the enrichment factors are in the range from 49 (naphthalene) to 158 (fluoranthene). The proposed procedure has been applied for the determination of thirteen PAHs in water samples (tap, river, well and reservoir ones) with recoveries in the range from 75 to 102%. PMID:23601292

Galán-Cano, Francisco; Alcudia-León, María del Carmen; Lucena, Rafael; Cárdenas, Soledad; Valcárcel, Miguel

2013-04-02

220

Comparative metabolomic analysis of Saccharomyces cerevisiae during the degradation of patulin using gas chromatography-mass spectrometry.  

PubMed

A comparative metabolomic analysis was conducted on Saccharomyces cerevisiae cells with and without patulin treatment using gas chromatography-mass spectrometry-based approach. A total of 72 metabolites were detected and compared, including 16 amino acids, 29 organic acids and alcohols, 19 sugars and sugar alcohols, 2 nucleotides, and 6 miscellaneous compounds. Principle component analysis showed a clear separation of metabolome between the cells with and without patulin treatment, and most of the identified metabolites contributed to the separation. A close examination of the identified metabolites showed an increased level of most of the free amino acids, an increased level of the intermediates in the tricarboxylic acid cycle, a higher amount of glycerol, a changed fatty acid composition, and a decreased level of cysteine and glutathione in the cells with patulin treatment. This finding indicated a slower protein synthesis rate and induced oxidative stress in the cells with patulin treatment, and provided new insights into the effect of toxic chemicals on the metabolism of organisms. PMID:22159606

Shao, Suqin; Zhou, Ting; McGarvey, Brian D

2011-12-10

221

[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

222

Optimization of solid-phase microextraction for the gas chromatography/mass spectrometry analysis of persistent organic pollutants.  

PubMed

In this work, solid-phase microextraction (SPME) has been applied as an alternative for the selective extraction of 3 polybrominated diphenyl ethers (PBDEs), 2,2',4,4'-tetrabromodiphenyl ether (PBDE-47); 2,2',4,4',5-pentabromodiphenyl ether (PBDE-99); and 2,2',4,4',6-pentabromodiphenyl ether (PBDE-100), and 2 alkylphenols, 4-tert-OP and 4-NP, prior to their analysis by gas chromatography/mass spectrometry (GC/MS). The advantages of this technique are mainly its simplicity, cost-effectiveness, and time-saving sample preparation, as well as being a solvent-free technique. With the aim of optimizing the conditions for an efficient extraction of the studied compounds, different fiber coatings and the main parameters affecting the extraction procedure have been evaluated. The results obtained showed a good linearity in the range of concentrations investigated, and adequate relative standard deviation values were found according to the range accepted for SPME. Recovery values were in the range of 78-108%, and good detection and quantitation limits at ppt levels were obtained for both methods, allowing the determination of the selected compounds in samples at trace levels. The results obtained clearly show the potential of SPME for efficient concentration of the target compounds and also demonstrate the reliability of this extraction technique for their GC/MS analysis. PMID:15295899

Gago-Martínez, Ana; Nogueiras, María J; Rellán, Sandra; Prado, Juan; Alpendurada, María F; Vetter, Walter

223

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

224

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, Zoltán

2012-12-20

225

Analysis of endocrine disrupting compounds, pharmaceuticals and personal care products in sewage sludge by gas chromatography-mass spectrometry.  

PubMed

Endocrine disrupting compounds (EDCs) and pharmaceuticals and personal care products (PPCPs) have been acknowledged as emerging pollutants due to widespread contamination in environment. A rapid and reliable analytical method, based on ultrasonic extraction, clean up on Envi-carb cartridge, derivatized with N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA), and analyzed by gas chromatography-mass spectrometry (GC-MS), was developed for determination of 4 EDCs (bisphenol A, estrone, nonylphenol and octylphenol) and 10 PPCPs (acetylsalicylic acid, carbamazepine, clofibric acid, diclofenac, gemfibrozil, ibuprofen, ketoprofen, naproxen, paracetamol and triclosan) in sewage sludge. Mean recoveries of the target analytes, at different spike levels (40, 300 and 2000 ng/g), ranged from 57.9% to 103.1%. Relative standard deviations (RSDs) were in the range of 1.3-9.5% at different spiked levels. The limit of quantification (LOQ) ranged from 4.7 to 39 ng/g. The method was applied to sewage sludge samples from sewage treatment plants (STPs) in southern California. High concentrations of PPCPs and EDCs were found in sewage sludge, ranging from 1502 to 5327 ng/g dry weight. Appropriate disposal of sewage sludge was required to avoid secondary contamination. PMID:22284489

Yu, Yong; Wu, Laosheng

2011-12-17

226

[Determination of chlorophenol and pyrethroid preservatives in wooden furniture by solid phase extraction coupled with gas chromatography-mass spectrometry].  

PubMed

A method for the determination of 10 wood preservatives of chlorophenols (2,4-dichlorophenol, 2, 4, 6-trichlorophenol, 2, 4, 5-trichlorophenol, 2, 3, 4, 6-tetrachlorophenol, pentachlorophenol, lindane) and pyrethroids (permethrin, cyfluthrin, cypermethrin, delta-methrin) in furniture by solid phase extraction (SPE) coupled with gas chromatography-mass spectrometry (GC-MS) was developed. The furniture samples were extracted twice by ultrasonic extraction in methanol. The extract was then evaporated and acetylated by the acetic anhydride and potassium carbonate. Finally the reaction solution was purified by Oasis HLB SPE column. The wood preservatives were eluted by ethyl acetate and collected for analysis by GC-MS. The ten wood preservatives can be separated and determined successfully by this method. Under the optimized conditions, the detection limits of the six chlorophenol compounds were 1 mg/kg, and the four pyrethroid compounds were 5 mg/kg, and the spiked recoveries of the 10 wood preservatives in samples were in the range of 76.0% - 108.8%. Forty commercial wooden furniture samples were tested and lindane was found in some samples. The results showed that the method is accurate, rapid and sensitive. It can be effectively used to analyze the wood preservatives in wooden furniture. PMID:23016294

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

2012-06-01

227

Silicone discs as disposable enrichment probes for gas chromatography-mass spectrometry determination of UV filters in water samples.  

PubMed

This work describes an effective, low solvent consumption and affordable sample preparation approach for the determination of eight UV filters in surface and wastewater samples. It involves sorptive extraction of target analytes in a disposable, technical grade silicone disc (5 mm diameter?×?0.6 mm thickness) followed by organic solvent desorption, large volume injection (LVI), and gas chromatography-mass spectrometry determination. Final working conditions involved overnight extraction of 100-mL samples, containing 10% of methanol, followed by analytes desorption with 0.2 mL of ethyl acetate. The method provides linear responses between the limits of quantification (from 0.003 to 0.040 ng mL(-1)) and 10 ng mL(-1), an intra-day precision below 13%, and low matrix effects for surface, swimming pool, and treated sewage water samples. Moreover, the extraction yields provided by silicone discs were in excellent agreement with those achieved using polydimethylsiloxane-covered stir bars. Several UV filters were found in surface and sewage water samples, with the maximum concentrations corresponding to octocrylene. PMID:21336788

Negreira, N; Rodríguez, I; Rubí, E; Cela, R

2011-02-19

228

Direct analysis of intact glycidyl fatty acid esters in edible oils using gas chromatography-mass spectrometry.  

PubMed

Glycidyl esters (GE), fatty acid esters of glycidol, are process contaminants formed during edible oil processing. A novel direct method for the determination of intact GE in oils and fats based on gas chromatography-mass spectrometry (GC-MS) is presented. The method consists of a simple extraction step of GE from the lipid matrix, purification of the extract and isolation of GE by normal phase liquid chromatography (NPLC). Individual GE in the final fraction are separated and quantified by standard GC-MS operated in selected ion monitoring (SIM) mode. The setup and conditions of the GC-MS were optimized in such a way that thermal degradation of GE and artifact formation were prevented. The method exhibits very good performance parameters: the limit of detection was approximately 0.01mg/kg for the individual GE (corresponding to 0.002-0.003mg/kg of free glycidol), the repeatability was in the range of 5-12% for individual GE at levels above 0.1mg/kg, and recovery values ranged from 85 to 115% depending on the level and the chain identity of the GE. The comparison of experimental values with spiked levels and with the results obtained by other methods confirmed a good trueness. Over a period of several months of extensive use the method was found to be very reliable and rugged. PMID:23891377

Steenbergen, Herrald; Hrn?i?ík, Karel; Ermacora, Alessia; de Koning, Sjaak; Janssen, Hans-Gerd

2013-06-28

229

Determination of organoarsenicals in the environment by solid-phase microextraction-gas chromatography-mass spectrometry.  

SciTech Connect

The development of a method for the analysis of organoarsenic compounds that combines dithiol derivatization with solid-phase microextraction (SPME) sample preparation and gas chromatography-mass spectrometry (GC-MS) is described. Optimization focused on a SPME-GC-MS procedure for determination of 2-chlorovinylarsonous acid (CVAA), the primary decomposition product of the chemical warfare agent known as Lewisite. Two other organoarsenic compounds of environmental interest, dimethylarsinic acid and phenylarsonic acid, were also studied. A series of dithiol compounds was examined for derivatization of the arsenicals, and the best results were obtained either with 1,3-propanedithiol or 1,2-ethanedithiol. The derivatization procedure, fiber type, and extraction time were optimized. For CVAA, calibration curves were linear over three orders of magnitude and limits-of-detection were <6x10{sup -9} M in solution, the latter a more than 400x improvement compared to conventional solvent extraction GC-MS methods. A precision of <10% R.S.D. was typical for the SPME-GC-MS procedure. The method was applied to a series of water samples and soil/sediment extracts, as well as to aged soil samples that had been contaminated with Lewisite.

Szostek, B.; Aldstadt, J. H.; Environmental Research

1998-05-22

230

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

PubMed

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

2013-10-17

231

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.

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

232

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

2007-12-24

233

Determination of polychlorinated biphenyls in serum using gas chromatography-mass spectrometry with negative chemical ionization for exposure estimation.  

PubMed

A sensitive and selective method for the determination of 24 polychlorinated biphenyls (PCBs) by gas chromatography-mass spectrometry with negative chemical ionization (GC-MS-NCI) was applied for the recent needs of occupational exposure in waste incineration. The three most abundant ions were used in determining compounds with at least five chlorine atoms in the PCB molecule. Selecting ions Cl(35) and Cl(37) for di-, tri-, and tetrachlorinated PCBs resulted in reliable quantification of these compounds. The detection limits for the 24 individual compounds varied from 0.01 to 0.08 microg/l. The recovery of the method was 113+/-16%. Stability tests showed no degradation of the compounds studied during 6 weeks. The sum of 24 PCB compounds measured from the sera of workers in a disposal plant was 1.9-10.9 microg/l, and 0.3-3.0 microg/l for controls, respectively. The mean proportion of the low chlorinated PCB compounds (with four or less chlorine atoms) was 20% for workers in the disposal plant and 14% for the controls. PMID:12798172

Kontsas, Helena; Pekari, Kaija

2003-07-01

234

[Determination of migration of 25 primary aromatic amines from food contact plastic materials by gas chromatography-mass spectrometry].  

PubMed

A solid phase extraction (SPE) combination with gas chromatography-mass spectrometry (GC-MS) was developed for the determination of the migration of 25 primary aromatic amines (PAAs) from food contact plastic materials and articles. The samples were extracted by deionized water and 30 g/L acetic acid, and the pH value of the solution was adjusted to 8 - 10 with ammonia. The extracts were cleaned up and concentrated on an SPE column, then eluted by equal volume of methyl-tert-butyl ether and ethanol. The analysis of the target compounds was performed by GC-MS. The results indicated that the limits of detection were in the range of 0.4 -2.0 microg/kg for different PAAs. The recoveries and relative standard deviations (n = 7) of 10 microg/kg PAAs ranged from 51.6% -118.4% and 0.5% -9.8%, respectively, except the 2,4-diaminoanisole in the acid simulant. The effects of different experimental conditions such as the pH value and volume ratio of methyl-tert-butyl ether and ethanol were studied. The results showed that the method is accurate and stable, and could meet the requirement of the European Commission Regulation (EU) No 10/2011 for the determination of primary aromatic amines. It can be applied in the analysis of the primary aromatic amines in real food contact plastic material and article samples. PMID:23667989

Li, Ying; Li, Chengfa; Xiao, Daoqing; Liang, Feng; Chen, Zhinan; Schen, Xuhui; Sun, Xiaoying; Li, Yongtao

2013-01-01

235

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

2013-02-26

236

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

PubMed

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

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

2010-12-28

237

Gas chromatography/mass spectrometry based hair steroid profiling may reveal pathogenesis in hair follicles of the scalp.  

PubMed

A method of steroid profiling, including androgens, progestins, corticoids and sterols, was developed to evaluate the concentrations of steroids as well as the activities of the enzymes responsible for steroidogenesis in hair by gas chromatography/mass spectrometry. The extraction efficiencies of steroids from the hair matrix were improved by ultrasonication for 1?h at 50?°C. The overall recoveries ranged from 71 to 132%, with a limit of quantification for all analytes ranging from 1 to 50?ng/g. The devised method was used to identify the metabolic changes for both male-pattern baldness (MPB) and the drug efficiency of dutasteride, which inhibits 5?-reductase. Increased dihydrotestosterone levels and the dihydrotestosterone/testosterone (DHT/T) ratio, which is responsible for the 5?-reductase activity, were observed in the MPB patients. A dutasteride treatment resulted in decreases in the DHT and 5?-androstanedione concentrations and DHT/T ratio in the hair samples. Hair steroid profiling reflects the sebaceous status in the scalp and may be useful for monitoring the metabolic responses to both the disease and drug actions. PMID:21488116

Jung, Hyun-Jin; Kim, Sun Ju; Lee, Won-Yong; Chung, Bong Chul; Choi, Man Ho

2011-05-15

238

Simultaneous determination of fuel oxygenates and BTEX using direct aqueous injection gas chromatography mass spectrometry (DAI-GC/MS).  

PubMed

A direct aqueous injection-gas chromatography/mass spectrometry (DAI-GC/MS) method for trace analysis of gasoline components in water is presented. The method allows for the simultaneous quantification of the following solutes: methyl tert-butyl ether (MTBE), its major degradation products (tert-butyl formate, tert-butyl alcohol (TBA), methyl acetate, and acetone), and possible substitutes of MTBE as an octane enhancer in gasoline (tert-amyl methyl ether, ethyl tert-butyl ether) as well as benzene, toluene, ethylbenzene, p-xylene, m-xylene, and o-xylene (BTEX). No enrichment or pretreatment steps are required, and sample volumes of only 50 microL are needed for analysis. The detection limits in two different matrixes (spiked lake water and contaminated groundwater) are < or = 2 microg/L for most analytes and < 0.2 microg/L for MTBE, benzene, and toluene. The accuracy of the DAI-GC/MS method was excellent as determined from comparison with headspace-GC/MS and purge-and-trap-GC/MS. The DAI-GC/MS method has been applied to various environmental studies, which demonstrated its versatility. The applications comprised both laboratory (MTBE degradation in water treatment, quantification of polar gasoline components) and field (MTBE degradation ata gasoline spill site) investigations. PMID:12026992

Zwank, Luc; Schmidt, Torsten C; Haderlein, Stefan B; Berg, Michael

2002-05-01

239

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

PubMed

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

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

2010-09-30

240

Sensitive determination of hydrazine in water by gas chromatography-mass spectrometry after derivatization with ortho-phthalaldehyde.  

PubMed

A gas chromatography-mass spectrometric (GC-MS) method has been established for the determination of hydrazine in drinking water and surface water. This method is based on the derivatization of hydrazine with ortho-phthalaldehyde (OPA) in water. The following optimum reaction conditions were established: reagent dosage, 40 mg mL(-1) of OPA; pH 2; reaction for 20 min at 70 °C. The organic derivative was extracted with methylene chloride and then measured by GC-MS. Under the established condition, the detection and the quantification limits were 0.002 ?g L(-1) and 0.007 ?g L(-1) by using 5.0-mL of surface water or drinking water, respectively. The calibration curve showed good linearity with r(2)=0.9991 (for working range of 0.05-100 ?g L(-1)) and the accuracy was in a range of 95-106%, and the precision of the assay was less than 13% in water. Hydrazine was detected in a concentration range of 0.05-0.14 ?g L(-1) in 2 samples of 10 raw drinking water samples and in a concentration range of 0.09-0.55 ?g L(-1) in 4 samples of 10 treated drinking water samples. PMID:23498124

Oh, Jin-Aa; Park, Ju-Hyun; Shin, Ho-Sang

2013-01-25

241

Determination of chloro-s-triazines including didealkylatrazine using solid-phase extraction coupled with gas chromatography-mass spectrometry.  

PubMed

Chloro-s-triazines are a class of compounds comprising atrazine, simazine, propazine, cyanazine and their chlorinated metabolites. The US Environmental Protection Agency (EPA) has determined that selected chloro-s-triazines--atrazine, simazine, propazine, deethylatrazine, deisopropylatrazine, and didealkylatrazine--have a common mode of toxicity related to endocrine disruption. In this paper, a dual-resin solid-phase extraction (SPE) gas chromatography-mass spectrometry (GC-MS) method is reported that provides for each of these chloro-s-triazines including the polar metabolite, didealkylatrazine. The method utilizes deuterated internal standards for quantitation and terbuthylazine as a recovery standard. The limit-of-detection was 0.01 microg/L for simazine, deethylatrazine, deisopropylatrazine and didealkylatrazine, and 0.02 microg/L for atrazine and propazine in surface water. Mean recoveries for 0.5 and 3.0 microg/L spikes for atrazine, simazine, propazine, deethylatrazine, deisopropylatrazine and didealkylatrazine were 94, 104, 103, 110, 108 and 102%, respectively, in surface water. The method was also validated by matrix spikes into fourteen different raw and treated natural surface waters. This method is useful for monitoring "total chloro-s-triazines" in both raw and treated drinking waters. PMID:15739890

Jiang, Hua; Adams, Craig D; Koffskey, Wayne

2005-02-01

242

Total organic carbon and gas chromatography: Mass spectroscopic methods to determine total carbon and hydrocarbons in mercuric iodide single crystals  

SciTech Connect

Total organic carbon was by measuring the CO/sub 2/ produced by combustion in a sealed quartz vessel. The CO/sub 2/ was quantified by nondispersive IR and by titration using commercial detectors. The total organic carbon was found to be around 10 to 100 ..mu..g/g in both starting materials and in single crystals. Gas chromatography--mass spectroscopy (GC/MS) measurements were made hexane extracts of mercuric iodide (HgI/sub 2/) dissolved in potassium iodide solution. Hydrocarbons starting with C/sub 10/ (DIENE) and up to C/sub 26/ were found. In addition, phthalates, such as diethyl and dioctyl phthalate were also found. Some of the organic compounds, for example, such hydrocarbons as branched nC/sub 16/, nC/sub 20/, nC/sub 21/, nC/sub 22/, nC/sub 23/, and nC/sub 24/, were present in some HgI/sub 2/ materials in quantities of the order of weight ppM, but were eliminated in the purification process and were not found in the single crystals. Other organic compounds such as the phthalates were not always eliminated and were identified in the single crystals. In general, the GC/MS could identify only hydrocarbons of C/sub 10/ and higher could account for few percentages of the total organic carbon determined by oxidation. 10 refs., 7 figs., 4 tabs.

Steinberg, S.; Kaplan, I.; Schieber, M..; Ortale, C.; Skinner, N.; van den Berg, L.

1987-01-01

243

[Application of single drop microextraction in the determination of phthalate esters in food by gas chromatography-mass spectrometry].  

PubMed

A novel, simple, fast and environment-friendly method based on single drop microextraction (SDME) was developed for the determination of phthalate esters in food by gas chromatography-mass spectrometry (GC-MS). The effects of the nature of organic solvents, microdrop volume, the depth of microdrop in sample solution, extration time and stirring rate on the extraction efficiency were investigated separately. The optimal SDME conditions, 2.0 microL of toluene, 0.75 cm of the depth of microdrop, 1 000 r/min of stirring rate and 20 min of extraction time, were obtained and used for the analysis of dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), dioctyl phthalate (DOP) and diethylhexyl phthalate (DEHP) in food. At first, a sample was dissolved with de-ionized water and then extracted with ultrasonication for 15 min. Then, it was filtrated and the solution was extracted and concentrated by a single drop of a solvent. Finally, it was analyzed by GC-MS. The reproducibility, linearity, recovery, and limit of detection of the method were studied. The results showed that the limits of detection (LOD) were between 25 ng/L and 0.8 mg/L. The overall recoveries were 87.1% - 114.4% with the relative standard deviations of 4.9% - 11.6%. This method has been successfully applied to the analysis of food samples. PMID:17432572

Li, Meigui; Li, Yuanxing; Mao, Liqiu

2007-01-01

244

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

2006-10-27

245

Headspace-trap gas chromatography-mass spectrometry for determination of sulphur mustard and related compounds in soil.  

PubMed

Methods for trace determination of sulphur mustard (HD) and some related cyclic sulphur compounds in soil samples have been developed using headspace-trap in combination with gas chromatography-mass spectrometry (GC-MS). Two quite different types of soil were employed in the method optimisation (sandy loam and silty clay loam). Prior to analysis, water saturated with sodium chloride was added to the samples, at a water to soil ratio of 1:1. A detection limit of 3 ng/g was achieved for HD, while the cyclic sulphur compounds 1,4-thioxane, 1,3-dithiolane and 1,4-dithiane could be detected at 0.2-0.7 ng/g. The methods were validated in the concentration range from the limit of quantification (LOQ) to hundred times LOQ. The within assay precision at fifty times LOQ was 6.9-7.3% relative standard deviation (RSD) for determination of the cyclic sulphur compounds, and 15% RSD for determination of HD. Recoveries were in the range of 43-60% from the two soil types. As the technique requires very little sample preparation, the total time for sample handling and analysis was less than 1h. The technique was successfully employed for the determination of cyclic sulphur compounds in a sediment sample from an old dumping site for chemical munitions, known to contain HD degradation products. PMID:20189185

Røen, Bent T; Unneberg, Erik; Tørnes, John Aa; Lundanes, Elsa

2010-02-06

246

Enzyme-linked immunosorbent assay compared with gas chromatography/mass spectrometry for the determination of triazine herbicides in water.  

PubMed

An enzyme-linked immunosorbent assay (ELISA) was compared to a gas chromatography/mass spectrometry (GC/MS) procedure for the analysis of triazine herbicides and their metabolites in surface water and groundwater. Apparent recoveries from natural water and spiked water by both methods were comparable at 0.2-2 micrograms/L. Solid-phase extraction (SPE) was examined also, and recoveries were determined for a suite of triazine herbicides. A significant correlation was obtained between the ELISA and GC/MS method for natural water samples that were extracted by SPE. Because ELISA was developed with an atrazine-like compound as the hapten with conjugation at the 2-position, it was selective for triazines that contained both ethyl and isopropyl side chains. Concentrations for 50% inhibition (IC50) were as follows: atrazine, 0.4 microgram/L; ametryne, 0.45 microgram/L; prometryn and propazine, 0.5 microgram/L; prometon, 0.7 microgram/L; simazine and terbutryn, 2.5 micrograms/L; hydroxyatrazine, 28 micrograms/L; deethylatrazine and deisopropylatrazine, 30 micrograms/L; cyanazine, 40 micrograms/L; didealkylatrazine had no response. The combination of screening analysis by ELISA, which requires no sample preparation and works on 160 microL of sample, and confirmation by GC/MS was designed for rapid, inexpensive analysis of triazine herbicides in water. PMID:2240580

Thurman, E M; Meyer, M; Pomes, M; Perry, C A; Schwab, A P

1990-09-15

247

Qualitative screening for volatile organic compounds in human blood using solid-phase microextraction and gas chromatography-mass spectrometry.  

PubMed

A fast and simple screening procedure using solid-phase microextraction and gas chromatography-mass spectrometry (SPME-GC-MS) in full-scan mode for the determination of volatile organic compounds (VOC) is presented. The development of a fast and simple screening technique for the simultaneous determination of various volatiles is of great importance, because of their widespread use, frequent occurrence in forensic toxicological questions and the fact that there is often no hint on involved substances at the crime scene. To simulate a screening procedure, eight VOC with different chemical characteristics were chosen (isoflurane, halothane, hexane, chloroform, benzene, isooctane, toluene and xylene). To achieve maximum sensitivity, variables that influence the SPME process, such as type of fiber, extraction and desorption temperature and time, agitation and additives were optimized by preliminary studies and by means of a central composite design. The limits of detection and recoveries ranged from 2.9 microg/l (xylene) to 37.1 microg/l (isoflurane) and 7.9% (chloroform) to 61.5% (benzene), respectively. This procedure can be used to answer various forensic and toxicological questions. The short time taken for the whole analytical procedure may make its eventual adoption for routine analysis attractive. PMID:20301087

Gottzein, Anne Kathrin; Musshoff, Frank; Madea, Burkhard

2010-04-01

248

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

2008-01-13

249

Innovative microwave-assisted oximation and silylation procedures for metabolomic analysis of plasma samples using gas chromatography-mass spectrometry.  

PubMed

Analysis of plasma metabolomic samples by gas chromatography-mass spectrometry always requires comprehensive pretreatment including oximation and silylation. Although heating block (HB) is a commonly used method, it is time consuming. This study describes an extremely time-effective microwave-assisted (MA) oximation and silylation approach for metabolomic study of plasma samples. The Box-Behnken design was employed to optimize the MA conditions by means of oximation at 65 W for 100 s and then silylation through 180 s incubation with 230 W microwave irradiation. The results showed that microwave irradiation decreased the sample preparation time from approximately 180 min to 5 min without loss of information for the metabolites in plasma samples. Both the HB method and the developed MA method were applied in plasma metabolomic study of sulfur mustard intoxication. Partial least-squares discriminant analysis (PLS-DA) was used to globally understand the metabolic changes, and multi-criteria assessment was used to select the most significant and reliable variables as potential biomarkers. The data obtained by the MA method were in good correlation with the HB method. Compared with HB method, the newly developed MA oximation and silylation of plasma metabolome samples was more efficient and time-effective and may prove to be an attractive alternative for high-throughput sample preparation in plasma metabolomics. PMID:22841665

Hong, Zhanying; Lin, Zebin; Liu, Yue; Tan, Guangguo; Lou, Ziyang; Zhu, Zhenyu; Chai, Yifeng; Fan, Guorong; Zhang, Junping; Zhang, Liming

2012-07-20

250

Simultaneous determination of cyanide and thiocyanate in plasma by chemical ionization gas chromatography mass-spectrometry (CI-GC-MS).  

PubMed

An analytical method utilizing chemical ionization gas chromatography-mass spectrometry was developed for the simultaneous determination of cyanide and thiocyanate in plasma. Sample preparation for this analysis required essentially one-step by combining the reaction of cyanide and thiocyanate with pentafluorobenzyl bromide and simultaneous extraction of the product into ethyl acetate facilitated by a phase-transfer catalyst, tetrabutylammonium sulfate. The limits of detection for cyanide and thiocyanate were 1 ?M and 50 nM, respectively. The linear dynamic range was from 10 ?M to 20 mM for cyanide and from 500 nM to 200 ?M for thiocyanate with correlation coefficients higher than 0.999 for both cyanide and thiocyanate. The precision, as measured by %RSD, was below 9 %, and the accuracy was within 15 % of the nominal concentration for all quality control standards analyzed. The gross recoveries of cyanide and thiocyanate from plasma were over 90 %. Using this method, the toxicokinetic behavior of cyanide and thiocyanate in swine plasma was assessed following cyanide exposure. PMID:22941221

Bhandari, Raj K; Oda, Robert P; Youso, Stephanie L; Petrikovics, Ilona; Bebarta, Vikhyat S; Rockwood, Gary A; Logue, Brian A

2012-09-04

251

Rapid determination and confirmation of biogenic amines in tuna loin by gas chromatography/mass spectrometry using ethylchloroformate derivative.  

PubMed

A gas chromatography-mass spectrometry (GC/MS) method is described for the easy rapid determination and simultaneous confirmation of the biogenic amines putrescine (PUT), cadaverine (CAD), histamine (HTA), and spermidine (SPD) in fresh frozen tuna loin. The method can also be used to monitor tyramine (TYR). The method involves homogenization of fish tissue, extraction of biogenic amines into trichloroacetic acid solution, centrifugation, alkalization, and derivatization of supernatant with ethylchloroformate. All seafood species were fortified to contain 2.5, 5.0, 10.0, 12.5, and 25.0 microg/g (ppm) PUT, CAD, and SPD; and 10.0, 20.0, 40.0, 50.0, and 100.0 microg/g (ppm) HTA. Determination was based on standard curves for each analyte using peak areas with matrix standards equivalent to a concentration range bracketing the spike level. A set of 5 matrix controls (unfortified tuna tissue) was also analyzed; only endogenous SPD was found in all samples. The interassay average recoveries ranged from 57 to 79% across analytes and spike levels. PMID:17225607

Marks, Heidi S; Anderson, Collin R

252

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

2012-09-20

253

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

2012-06-26

254

Comparative Analysis of Mass Spectral Similarity Measures on Peak Alignment for Comprehensive Two-Dimensional Gas Chromatography Mass Spectrometry  

PubMed Central

Peak alignment is a critical procedure in mass spectrometry-based biomarker discovery in metabolomics. One of peak alignment approaches to comprehensive two-dimensional gas chromatography mass spectrometry (GC×GC-MS) data is peak matching-based alignment. A key to the peak matching-based alignment is the calculation of mass spectral similarity scores. Various mass spectral similarity measures have been developed mainly for compound identification, but the effect of these spectral similarity measures on the performance of peak matching-based alignment still remains unknown. Therefore, we selected five mass spectral similarity measures, cosine correlation, Pearson's correlation, Spearman's correlation, partial correlation, and part correlation, and examined their effects on peak alignment using two sets of experimental GC×GC-MS data. The results show that the spectral similarity measure does not affect the alignment accuracy significantly in analysis of data from less complex samples, while the partial correlation performs much better than other spectral similarity measures when analyzing experimental data acquired from complex biological samples.

2013-01-01

255

Simultaneous determination of cannabidiol, cannabinol, and delta9-tetrahydrocannabinol in human hair by gas chromatography-mass spectrometry.  

PubMed

An analytical method was developed for evaluating the cannabidiol (CBD), cannabinol (CBN), and delta9-tetrahydrocannabinol (delta9-THC) level in human hair using gas chromatography-mass spectrometry (GC-MS). Hair samples (50 mg) were washed with isopropyl alcohol and cut into small fragments (< 1 mm). After adding a deuterated internal standard, the hair samples were incubated in 1.0 M NaOH for 10 min at 95 degrees C. The analytes from the resulting hydrolyzed samples were extracted using a mixture of n-hexane-ethyl acetate (75:25, v/v). The extracts were then evaporated, derivatized, and injected into the GC-MS. The recovery ranges of CBD, CBN, and delta9-THC at three concentration levels were 37.9-94.5% with good correlation coefficients (r2 >0.9989). The intra-day precision and accuracy ranged from -9.4% to 17.7%, and the inter-day precision and accuracy ranged from -15.5% to 14.5%, respectively. The limits of detection (LOD) for CBD, CBN, and delta9-THC were 0.005, 0.002, and 0.006 ng/mg, respectively. The applicability of this method of analyzing the hair samples from cannabis abusers was demonstrated. PMID:16212242

Kim, Jin Young; Suh, Sung Ill; In, Moon Kyo; Paeng, Ki-Jung; Chung, Bong Chul

2005-09-01

256

Development of analysis of volatile polyfluorinated alkyl substances in indoor air using thermal desorption-gas chromatography-mass spectrometry.  

PubMed

The study attempts to utilize thermal desorption (TD) coupled with gas chromatography-mass spectrometry (GC-MS) for determination of indoor airborne volatile polyfluorinated alkyl substances (PFASs), including four fluorinated alcohols (FTOHs), two fluorooctane sulfonamides (FOSAs), and two fluorooctane sulfonamidoethanols (FOSEs). Standard stainless steel tubes of Tenax/Carbograph 1 TD were employed for low-volume sampling and exhibited minimal breakthrough of target analytes in sample collection. The method recoveries were in the range of 88-119% for FTOHs, 86-138% for FOSAs, exhibiting significant improvement compared with other existing air sampling methods. However, the widely reported high method recoveries of FOSEs were also observed (139-210%), which was probably due to the structural differences between FOSEs and internal standards. Method detection limit, repeatability, linearity, and accuracy were reported as well. The approach has been successfully applied to routine quantification of targeted PFASs in indoor environment of Singapore. The significantly shorter sampling time enabled the observation of variations of concentrations of targeted PFASs within different periods of a day, with higher concentration levels at night while ventilation systems were shut off. This indicated the existence of indoor sources and the importance of building ventilation and air conditioning system. PMID:22494639

Wu, Yaoxing; Chang, Victor W-C

2012-03-23

257

Determination of hydroxylated stilbenes in wine by dispersive liquid-liquid microextraction followed by gas chromatography mass spectrometry.  

PubMed

Dispersive liquid-liquid microextraction (DLLME) has been proposed, for first time, to determine the concentrations of three hydroxylated stilbenes (trans-isomers of pterostilbene, resveratrol and piceatannol) in wine samples. DLLME was preceded by an acetylation step and followed by gas chromatography mass spectrometry (GC-MS) to achieve limits of quantification (LOQs) comprised between 0.6 and 5 ngmL(-1), linear responses up to 5000 ngmL(-1), excellent accuracy (overall recoveries ranged from 90 to 102% for samples spiked at different levels from 50 to 1000 ngmL(-1)) and standard deviations below 12%. Sample intake and organic solvents consumption remained at 1 and 0.6 mL, respectively, with a total sample preparation (derivatization and concentration) time around 15 min. The trans-isomers of piceatannol and resveratrol were measured in wine samples at concentrations up to 0.5 and 2.6 ?gmL(-1), respectively. In addition to their cis-forms, the dihydrogenated analogues of both antioxidants were detected in red wines. To the best of our knowledge, this is the first report describing the presence of dihydropiceatannol in wine. On the other hand, pterostilbene remained below the detection limits of the method in all the processed samples. In addition to the relative low levels of this stilbene existing in grapes, its lipophilic character appears to limit the transfer from grapes skins to wine. PMID:22939207

Rodríguez-Cabo, T; Rodríguez, I; Cela, R

2012-08-17

258

Validation of a method to detect cocaine and its metabolites in nails by gas chromatography-mass spectrometry.  

PubMed

The objective of the present work was to compare previously published methods and provide validation data to detect simultaneously cocaine (COC), benzoylecgonine (BE) and norcocaine (NCOC) in nail. Finger and toenail samples (5mg) were cut in very small pieces and submitted to an initial procedure for external decontamination. Methanol (3 ml) was used to release analytes from the matrix. A cleanup step was performed simultaneously by solid-phase extraction (SPE) and the residue was derivatized with pentafluoropropionic anhydride/pentafluoropropanol (PFPA/PFP). Gas chromatography-mass spectrometry (GC-MS) was used to detect the analytes in selected ion monitoring mode (SIM). Confidence parameters of validation of the method were: recovery, intra- and inter-assay precision, as well as limit of detection (LOD) of the analytes. The limits of detection were: 3.5 ng/mg for NCOC and 3.0 ng/mg for COC and BE. Good intra-assay precision was observed for all detected substances (coefficient of variation (CV)<11%). The inter-assay precision for norcocaine and benzoylecgonine were <4%. For intra- and inter-assay precision deuterated internal standards were used. Toenail and fingernail samples from eight declared cocaine users were submitted to the validated method. PMID:16183230

Valente-Campos, Simone; Yonamine, Mauricio; de Moraes Moreau, Regina Lucia; Silva, Ovandir Alves

2005-09-23

259

Simultaneous determination of 2-naphthol and 1-hydroxy pyrene in urine by gas chromatography-mass spectrometry.  

PubMed

A gas chromatography-mass spectrometric (GC-MS) method was developed for the determination of 2-naphthol (2-NAP) and 1-hydroxypyrene (1-HOP) in human urine. Extraction from urine after the enzyme hydrolysis with ?-glucuronidase/arylsulfatase was achieved with a liquid extraction using 5 mL of pentane. After addition of 50 ?L of N-methyl-N-(tert-butyldimethylsilyl) trifluoroacetamide (MTBDMSTFA) to prevent the loss of 2-NAP during drying, the extract was completely dried and derivatized with MTBDMSTFA for 30 min at 60 °C. The accuracies were in the range of 96-109% at a concentration of 0.5, 10 and 25 ?g/L and their precisions were less than 15%. Method detection limits of 2-NAP and 1-HOP were 0.07 and 0.01 ?g/L, respectively. This method was used to analyze twenty urine samples, and they were found in the concentration range <0.07-13.7 ?g/L (2-NAP) and <0.01-0.88 ?g/L (1-HOP). The concentrations of 2-NAP and 1-HOP were well correlated to those of naphthalene and pyrene in blood, respectively. PMID:21277841

Shin, Ho-Sang; Lim, Hyun-Hee

2011-01-14

260

Determination of 1,3-dichloropropanol in soy and related sauces by using gas chromatography/mass spectrometry.  

PubMed

A gas chromatography/mass spectrometry method for 3-MCPD in foods and food ingredients was modified for the determination of 1,3-DCP in soy and related sauces. The method was validated by using a blank soy sauce. The detection limit, quantitation limit and recoveries were determined, and identities were confirmed by mass spectrometry on the basis of analyses of test portions spiked with 1,3-DCP at 10, 25, 50 and 100 ng g(-1). The spiked test portions were quantitated by using an internal standard calibration curve. For the spiked test portions, the mean internal standard-corrected recovery for 1,3-DCP was 100% with a relative standard deviation of 1.32%. The limits of detection and quantitation were determined as 0.055 and 0.185 ng g(-1), respectively. The method also was compared with a headspace GC/MS method recently developed by the UK's Central Science Laboratory. Results from the method comparison showed that the recoveries for the spiked test portions, as well as the amounts of 1,3-DCP found in the retail products, were comparable. PMID:14594674

Nyman, P J; Diachenko, G W; Perfetti, G A

2003-10-01

261

A sensitive assay of 5-fluorouracil in plasma by gas chromatography-mass spectrometry.  

PubMed Central

1 A gas chromatographic-mass spectrometric method was developed for determining 5-fluorouracil in plasma, using methylated thymine as an internal standard. 2 5-fluorouracil was extracted from plasma by a novel procedure which removed plasma components interferring with the sensitivity of the assay. The method included heating the plasma, washing with ether and extracting the drug under optimum conditions. 3 The sensitivity of the assay was 10 ng/ml plasma, sufficient to determine the low concentrations of 5-fluorouracil found in plasma during continuous infusion of the drug in patients receiving chemotherapy for cancer.

Hillcoat, B L; Kawai, M; McCulloch, P B; Rosenfeld, J; Williams, C K

1976-01-01

262

Negative ion chemical ionization gas chromatography/mass spectrometry of valproic acid metabolites.  

PubMed

A negative ion chemical ionization (NICI) gas chromatographic/mass spectrometric method is described for the identification of 15 valproic acid (VPA) metabolites as their pentafluorobenzyl derivatives. Samples analyzed were serum, urine and saliva taken from a volunteer on VPA at steady state and also given selected doses of (2H6)VPA. Metabolite peaks were identified by comparison to synthetic standards. All the metabolites, like the parent drug, produced abundant [M - 181]- ions, except 3-keto VPA, which gave an [M - 181 - CO2]- ion. Using the NICI method, two new VPA metabolites were identified. One of these metabolites was characterized as 4'-keto-2-ene VPA by synthesis, while the second one appeared to be a positional isomer of 4'-keto-2-ene VPA. The sensitivity of the method was also sufficient to detect metabolites of VPA in saliva. The ratio of the levels of (Z)-2-ene VPA to (E)-2-ene VPA was much greater in saliva than in serum, suggesting stereoselective plasma protein binding or transport of these two metabolites. The lower limit of detection for the quantification of VPA in serum or saliva was 2 ng ml-1. PMID:2508808

Kassahun, K; Burton, R; Abbott, F S

1989-10-01

263

[Simultaneous determination of ten organotin compounds in polyvinyl chloride plastics using gas chromatography-mass spectrometry].  

PubMed

A rapid and effective gas chromatography coupled with mass spectrometry method has been developed systematically and studied for the simultaneous determination of 10 organotin compounds, dibutyltin-dichloride (DBT), n-butyltin-trichloride (MBT), triethyltinchloride (TET), fentin-chloride (TPhT), chlorotributylstannane (TBT), tri-n-propyltinchloride (TPrT), diphenyltin-dichloride (DPhT), tetrabutyltin (TeBT), di-n-octyltin-dichloride (DOT), phenyltin trichloride (MPhT)), in polyvinyl chloride (PVC) plastics. The PVC sample was dissolved with tetrahydrofuran and the polymer in the sample was precipitated with methanol, and then the target compounds were derivatized with sodium tetraethylborate and extracted with hexane under ultrasonication. The qualitative and quantitative analysis were carried out by GC-MS and the total ion chromatogram and selected ion chromatogram were obtained. The derivatization and extraction conditions, such as the derivatization time, derivatization pH value, dosages of derivatization reagent and precipitation reagent were optimized. The good linearities, recoveries and precisions were obtained. The linearity ranges were 0.5 - 50 mg/L. The linearity correlation coefficients of 10 organotin compounds were between 0.997 8 and 0.999 7. The average recoveries were 84.23% - 109.1% with relative standard deviations of 4.24% - 10.75%. The established method has been successfully applied to the determination of organotin compounds in PVC plastics. PMID:19449544

Li, Ying; Li, Bin; Liu, Li; Zhang, Chen; Wu, Jingwu; Liu, Zhihong; Li, Xintian

2009-01-01

264

Using gas chromatography/mass spectroscopy fingerprint analyses to document process and progress of oil degradation  

SciTech Connect

One of the challenges in testing the effectiveness of bioremediation products is the lack of a standardized testing protocol. One requirement of any such evaluation is baseline and benchmark analyses of the oil and its degradation processes. The method described uses high resolution gas chromatography maw spectroscopy (GC/MS). This method has been adapted from oil fingerprinting techniques used by our group for oil spill response to major spills such as T/V Exxon Valdez and T/V Megaborg. It results in a high degree of chemical and spectral resolution from a single analysis that allows quantification of saturated hydrocarbons, polynuclear aromatic hydrocarbons (PAHs), sulfur heterocycles and selected biomarkers such as hopanes and steranes. High resolution GC/MS and compound specific analyses are a viable and efficient method of analyzing the extent and progress of oil bioremediation and that it should be possible to standardize the method for monitoring the biodegradation of oil. Data are also presented that show increased useful information obtained from this method and suggest possible future uses for this expanded database. 14 refs., 4 figs., 1 tab.

Roques, D.E.; Overton, E.B.; Henry, C.B. [Louisiana State Univ., Baton Rouge, LA (United States)

1994-07-01

265

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

USGS Publications Warehouse

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

Hladik, Michelle L.; McWayne, Megan M.

2012-01-01

266

Targeted mass spectral ratio analysis: a new tool for gas chromatography-mass spectrometry.  

PubMed

An algorithm, referred to as targeted mass spectral ratio analysis (TMSRA) is presented whereby the ratios between intensities as a function of mass channel (m/z) of a target analyte mass spectrum are used to automatically determine which m/z are sufficiently pure to quantify the analyte in a sample gas chromatogram. The standard perfluorotributylamine (PFTBA) was used to evaluate the reproducibility of the collected mass spectra, which aided in selecting a mass spectral threshold for TMSRA application to a subsequent case study. Results with PFTBA suggested that a threshold of all m/z at or above 1% of the highest recorded m/z intensity should be included for targeted analysis. For the case study, 1-heptene was selected as the target analyte and n-heptane was selected as the interfering compound. These two compounds were chosen since their mass spectra are very similar. Chromatographic data containing a pure peak for these analytes were extracted, and mathematically added at various temporal offsets to generate various degrees of chromatographic resolution, R(s), for the purpose of evaluating algorithm performance, and indeed, TMSRA successfully quantified 1-heptene. At the higher R(s) studied (0.6 ? R(s) ? 1.5) a deviation within ± 1% and a RSD generally below 1% were achieved for 1-heptene quantification. As the R(s) decreased, the deviation and RSD both increased. At a R(s)=0, a deviation of ? 9% and a RSD of ? 9% were achieved. PMID:23200387

Kehimkar, Benjamin; Hoggard, Jamin C; Nadeau, Jeremy S; Synovec, Robert E

2012-10-23

267

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

PubMed

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

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

2011-08-04

268

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

269

Headspace solid-phase microextraction-gas chromatography--mass spectrometry analysis of the volatile compounds of Evodia species fruits.  

PubMed

In this study the investigation of the aroma compounds of dried fruits of Evodia rutaecarpa (Juss.) Benth. and E. rutaecarpa (Juss.) Benth. var. officinalis (Dode) Huang (i.e. E. officinalis Dode) (Rutaceae family) was carried out to identify the odorous target components responsible for the characteristic aroma of these valuable natural products. To avoid the traditional and more time-consuming hydrodistillation, the analyses were carried out by means of headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). The SPME headspace volatiles were collected using a divinylbenzene-carboxen-polydimethylsiloxane (DVB-CAR-PDMS) fiber. The extraction conditions were optimized using a response surface experimental design to analyze the effect of three factors: extraction temperature, equilibrium time and extraction time. The best response was obtained when the extraction temperature was around 80 degrees C, equilibrium time near 25 min and extraction time close to 18 min. Analyses were performed by GC-MS with a 5% diphenyl-95% dimethyl polysiloxane (30 m x 0.25 mm I.D., film thickness 0.25 microm) capillary column using He as the carrier gas and a programmed temperature run. The main components of the HS-SPME samples of E. rutaecarpa (concentration >3.0%) were limonene (33.79%), beta-elemene (10.78%), linalool (8.15%), myrcene (5.83%), valencene (4.73%), beta-caryophyllene (4.62%), linalyl acetate (4.13%) and alpha-terpineol (3.99%). As for E. officinalis, the major compounds were myrcene (32.79%), limonene (18.36%), beta-caryophyllene (9.92%), trans-beta-ocimene (6.04%), linalool (5.88%), beta-elemene (7.85%) and valencene (4.62%). PMID:16130723

Pellati, Federica; Benvenuti, Stefania; Yoshizaki, Fumihiko; Bertelli, Davide; Rossi, Maria Cecilia

2005-09-16

270

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

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

2012-04-09

271

Application of isotope dilution gas chromatography-mass spectrometry in analysis of organochlorine pesticide residues in ginseng root.  

PubMed

A highly accurate and precise method based on isotope dilution gas chromatography-mass spectrometry was developed for the determination of five matrix-bound organochlorine pesticides, namely, hexachlorobenzene and hexachlorocyclohexanes (alpha-, beta-, delta-, and gamma- isomers), in a reference sample of Panax gingseng. Identification of the analytes was confirmed under selective ion monitoring mode by the presence of two dominant ion fragments within the specific time windows (+/-1% of the relative retention time with respect to the calibration standards) and matching of relative ion intensities of the concerned ions in samples and calibration standards (within +/-5%). Quantification was based on the measurement of concentration ratios of the natural and isotopic analogues in the sample and calibration blends. To circumvent the tedious iterative process of exact isotope matching that is often used in isotope dilution mass spectrometry analysis, a single-point calibration procedure was adopted with the isotopic amount ratios in the sample and calibration blends close to unity (0.9-1.1). Under the described approach, intraday and interday repeatability of replicate analyses of organochlorine pesticides in the ginseng root sample were below 1.4%. The expanded relative uncertainty ranging from 4.0 to 6.5% at a coverage factor of 2 was significantly lower than those of conventional gas chromatographic methods using other calibration techniques (internal or external standards). A deviation of less than 2.0% from the certified values was achieved when applying the developed method to determine hexachlorobenzene, alpha-, and beta-hexachlorocyclohexane in a certified reference material (CRM), BCR-CRM 115. Because of the unavailability of relevant CRMs of herbal origins, the concerned ginseng root sample, after verification of the "true values" of the concerned organochlorine pesticides by the valid primary method, is suitable for serving as an in-house reference material for quality assurance and method validation purposes. PMID:17407316

Chan, Serena; Kong, Mei-Fong; Wong, Yiu-Chung; Wong, Siu-Kay; Sin, Della W M

2007-04-04

272

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

SciTech Connect

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

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

1992-10-15

273

Identification and quantification of polyfunctionalized hopanoids by high temperature gas chromatography-mass 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 10–30% 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.

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

2013-01-01

274

Technical advance: simultaneous analysis of metabolites in potato tuber by gas chromatography-mass spectrometry.  

PubMed

A new method is presented in which gas chromatography coupled to mass spectrometry (GC-MS) allows the quantitative and qualitative detection of more than 150 compounds within a potato tuber, in a highly sensitive and specific manner. In contrast to other methods developed for metabolite analysis in plant systems, this method represents an unbiased and open approach that allows the detection of unexpected changes in metabolite levels. Although the method represents a compromise for a wide range of metabolites in terms of extraction, chemical modification and GC-MS analysis, for 25 metabolites analysed in detail the recoveries were found to be within the generally accepted range of 70-140%. Further, the reproducibility of the method was high: the error occurring in the analysis procedures was found to be less than 6% for 30 out of 33 compounds tested. Biological variability exceeded the systematic error of the analysis by a factor of up to 10. The method is also suited for upscaling, potentially allowing the simultaneous analysis of a large number of samples. As a first example this method has been applied to soil- and in vitro-grown tubers. Due to the simultaneous analysis of a wide range of metabolites it was immediately apparent that these systems differ significantly in their metabolism. Furthermore, the parallel insight into many pathways allows some conclusions to be drawn about the underlying physiological differences between both tuber systems. As a second example, transgenic lines modified in sucrose catabolism or starch synthesis were analysed. This example illustrates the power of an unbiased approach to detecting unexpected changes in transgenic lines. PMID:10929108

Roessner, U; Wagner, C; Kopka, J; Trethewey, R N; Willmitzer, L

2000-07-01

275

Determination of aromatic amines in hair dye and henna samples by ion-pair extraction and gas chromatography–mass spectrometry  

Microsoft Academic Search

A gas chromatography–mass spectrometry (GC–MS) method has been proposed for the determination of carcinogenic and toxic aromatic amines in hair dye, henna and dyed hair samples. The method includes ion-pair extraction of aromatic amines from aqueous samples with bis-2-ethylhexylphosphate (BEHPA) released after solving the samples in acidic solution followed by sonication, derivatisation of compounds with isobutyl chloroformate (IBCF) and their

Mehmet Akyüz; ?evket Ata

2008-01-01

276

Photodegradation of organophosphorus insecticides – Investigations of products and their toxicity using gas chromatography–mass spectrometry and AChE-thermal lens spectrometric bioassay  

Microsoft Academic Search

Four organophosphorus compounds: azinphos-methyl, chlorpyrifos, malathion and malaoxon in aqueous solution were degraded by using a 125W xenon parabolic lamp. Gas chromatography–mass spectrometry (GC–MS) was used to monitor the disappearance of starting compounds and formation of degradation products as a function of time. AChE-thermal lens spectrometric bioassay was employed to assess the toxicity of photoproducts. The photodegradation kinetics can be

M. Bavcon Kralj; M. Franko; P. Trebše

2007-01-01

277

Characterization and purification of fatty acid methyl esters from the liver oil of the deep sea shark ( Centrophorus squamosus ) by gas chromatography-mass spectrometry and countercurrent chromatography  

Microsoft Academic Search

In the course of our studies on the location of marine products, we have directed our attention to the saponifiable fraction of the liver oil from the deep sea shark (Centrophorus squamosus). Different analytical and preparative techniques, such as high-performance liquid chromatography (HPLC), countercurrent chromatography (CCC), and gas chromatography-mass spectrometry [GC-MS, electron impact (EI) and positive-ion chemical ionization (PCI)] were

C. G. Bordier; N. Sellier; A. P. Foucault; F. Le Goffic

1994-01-01

278

Development of gas chromatography–mass spectrometry with microwave distillation and simultaneous solid-phase microextraction for rapid determination of volatile constituents in ginger  

Microsoft Academic Search

In this study, gas chromatography–mass spectrometry (GC–MS) following microwave distillation and solid-phase microextraction (MD–SPME) was developed for the analysis of essential oil compounds in fresh ginger. In the proposed method, the isolation, extraction and concentration of volatile components in ginger were carried out in one single step, using the MD–SPME technique, and the analytes on the SPME fiber were analyzed

Yingjia Yu; Taomin Huang; Bei Yang; Xiang Liu; Gengli Duan

2007-01-01

279

Determination of organic micropollutants in rainwater using hollow fiber membrane\\/liquid-phase microextraction combined with gas chromatography–mass spectrometry  

Microsoft Academic Search

A simple and rapid liquid-phase microextraction (LPME) method using a hollow fiber membrane (HFM) in conjunction with gas chromatography–mass spectrometry (GC–MS) is presented for the quantitative determination of 16 polycyclic aromatic hydrocarbons (PAHs) and 12 organochlorine pesticides (OCPs) in rainwater samples. The LPME conditions were optimized for achieving high enrichment of the analytes from aqueous samples, in terms of hollow

Chanbasha Basheer; Rajasekhar Balasubramanian; Hian Kee Lee

2003-01-01

280

Determination of low level nitrite and nitrate in biological, food and environmental samples by gas chromatography–mass spectrometry and liquid chromatography with fluorescence detection  

Microsoft Academic Search

Gas chromatography–mass spectrometry (GC–MS) and liquid chromatography with fluorescence detection (LC-FL) methods have been proposed for the determination of low level nitrite and nitrate in biological, food and environmental samples. The methods include derivatization of aqueous nitrite with 2,3-diaminonaphthalene (DAN), enzymatic reduction of nitrate to nitrite, extraction with toluene and chromatographic analyses of highly fluorescent 2,3-naphthotriazole (NAT) derivative of nitrite

Mehmet Akyüz; ?evket Ata

2009-01-01

281

Determination of 266 pesticide residues in apple juice by matrix solid-phase dispersion and gas chromatography–mass selective detection  

Microsoft Academic Search

A macro matrix solid-phase dispersion (MSPD) method was developed to extract 266 pesticides from apple juice samples prior to gas chromatography–mass selective detection (GC–MSD) determination. A 10g samples was mixed with 20g diatomaceous earth. The mixture was transferred into a glass column. Pesticide residues were leached with a 160mL hexane–dichloromethane (1:1) at 5mL\\/min. Two hundred and sixty-six pesticides were divided

Xiao-Gang Chu; Xiao-Zhong Hu; Hui-Yuan Yao

2005-01-01

282

Detection of prenatal exposure to several classes of environmental toxicants and their metabolites by gas chromatography–mass spectrometry in maternal and umbilical cord blood  

Microsoft Academic Search

We developed a sensitive method to detect several classes of pesticides and their metabolites in maternal and cord whole blood using electron-impact gas chromatography–mass spectrometry (GC–MS). The method can detect parent and metabolite compounds at levels of <0.10 and 0.20?g\\/mL, respectively, with high accuracy and recovery. Analysis of blood from mother–infant dyads from an area of high pesticide use in

M. L. Corrion; E OSTREAJR; D. M. Bielawski; N POSECIONJR; J. J. Seagraves

2005-01-01

283

Determination of pharmaceutical residues in waters by solid-phase extraction and large-volume on-line derivatization with gas chromatography–mass spectrometry  

Microsoft Academic Search

This work presents a modified method to analyze selected pharmaceutical residues (clofibric acid, ibuprofen, carbamazepine, naproxen, ketoprofen and diclofenac) in water samples. Various solid-phase extraction cartridges were investigated. The newly developed Oasis HLB (polystyrene-divinylbenzene-N-vinyl pyrrolidone terpolymer) solid-phase extraction (SPE) cartridge provides the optimal sample extraction results. The analytes were then identified and quantitatively determined by gas chromatography–mass spectrometry (GC–MS) via

Wan-Ching Lin; Hsin-Chang Chen; Wang-Hsien Ding

2005-01-01

284

New designer drug p-methoxymethamphetamine: studies on its metabolism and toxicological detection in urine using gas chromatography–mass spectrometry  

Microsoft Academic Search

Studies are described on the metabolism and the toxicological analysis of the new designer drug rac-p-methoxymethamphetamine (PMMA) in rat urine using gas chromatography–mass spectrometry (GC–MS). The identified metabolites indicated that PMMA was extensively metabolized mainly by O-demethylation to pholedrine and to a minor extent to p-methoxyamphetamine (PMA), 1-hydroxypholedrine diastereomers (one being oxilofrine), 4?-hydroxy-3?-methoxymethamphetamine and 4?-hydroxy-3?-methoxyamphetamine. The authors’ systematic toxicological analysis

Roland F. Staack; Josef Fehn; Hans H. Maurer

2003-01-01

285

Quantification of Neurosteroids in Rat Plasma and Brain Following Swim Stress and Allopregnanolone Administration Using Negative Chemical Ionization Gas Chromatography\\/Mass Spectrometry  

Microsoft Academic Search

A simplified method for the quantitative analysis of neurosteroids in rat plasma and brain is described. The method uses negative chemical ionization gas chromatography\\/mass spectrometry and involves the synthesis of pentafluorobenzyloxime\\/trimethylsilyl ether derivatives with excellent chromatographic and electron-capturing properties. Deuterium-labeled analogs of the steroids of interest were synthesized and used as internal standards. The steroids (allopregnanolone, epiallopregnanolone, pregnenolone, testosterone, and

Monique Vallée; Jeffery D. Rivera; George F. Koob; Robert H. Purdy; Robert L. Fitzgerald

2000-01-01

286

Identification of the position and the stereochemistry of the double bond in monounsaturated fatty acid methyl esters by gas chromatography\\/mass spectrometry of dimethyl disulfide derivatives  

Microsoft Academic Search

A single-step derivatization procedure using dimethyl disulfide (DMDS) is described for monounsaturated fatty acid esters (MUFAME). The analysis of DMDS adducts by gas chromatography\\/mass spectrometry is detailed: The mass spectra (electron impact 70 eV) show molecular ions (M\\/sup +\\/) and give key fragments that permit determination of the position of the original double bond. Alkylthiolation of Z- and E-MUFAME as

Pierre Scribe; Jean Guezennec; Jacques Dagaut; Claude Pepe; Alain Saliot

1988-01-01

287

Gas chromatography\\/mass spectrometry analysis of very long chain fatty acids, docosahexaenoic acid, phytanic acid and plasmalogen for the screening of peroxisomal disorders  

Microsoft Academic Search

Very long chain fatty acids (VLCFAs) and docosahexaenoic acid (DHA), phytanic acid, and plasmalogens are usually measured individually. A novel method for the screening of peroxisomal disorders, using gas chromatography\\/mass spectrometry (GC\\/MS), was developed. Saturated and unsaturated fatty acids, including VLCFAs and DHA, phytanic acid, and plasmalogen were detected by a selected ion monitoring-electron impact method, using 100 ?l of

Yasuhiko Takemoto; Yasuyuki Suzuki; Ryoko Horibe; Nobuyuki Shimozawa; Ronald J. A. Wanders; Naomi Kondo

2003-01-01

288

A comparison of pyrrolidide and picolinyl ester derivatives for the identification of fatty acids in natural samples by gas chromatography-mass spectrometry  

Microsoft Academic Search

The pyrrolidide and picolinyl ester derivatives of the fatty acids in two natural lipid samples rich in unsaturated fatty\\u000a acids, pig testis lipids and cod liver oil were satisfactorily resolved on capillary columns of fused silica coated with stationary\\u000a phases of varying polarity. The picolinyl esters, in particular, when subjected to gas chromatography-mass spectrometry on\\u000a a column containing a cross-linked

William W. Chrlstieo; Elizabeth Y. Brechanya; Susan B. Johnsonb; Ralph T. Holmanb

1986-01-01

289

Fast determination of synthetic polycyclic musks in sewage sludge and sediments by microwave-assisted headspace solid-phase microextraction and gas chromatography–mass spectrometry  

Microsoft Academic Search

One-step in situ microwave-assisted headspace solid-phase microextraction (MA-HS-SPME) followed by gas chromatography–mass spectrometry (GC–MS) analysis is presented as a fast and solvent-free technique to determine synthetic polycyclic musks in sewage sludge and sediment samples. Six synthetic polycyclic musks (galaxolide (HHCB), tonalide (AHTN), celestolide (ADBI), traseolide (ATII), cashmeran (DPMI) and phantolide (AHMI)) were selected in the method development and validation. The

Shin-Fang Wu; Wang-Hsien Ding

2010-01-01

290

Screening for estrogenic steroids in sheep and chicken by the application of enzyme-linked immunosorbent assay and a comparison with analysis by gas chromatography–mass spectrometry  

Microsoft Academic Search

A total of 146 sheep urine and 87 chicken muscle samples collected from birds sold in the State of Kuwait local market (originating from Brazil, Denmark, France and Turkey) were tested for residues of two xenobiotic estrogenic compounds, namely diethylstilbestrol (DES); and ethinylestradiol. The samples were analyzed using enzyme-linked immunosorbent assay (ELISA) and gas chromatography–mass spectrometry (GC–MS). Data obtained showed

Wajih N Sawaya; Khalid P Lone; Adnan Husain; Basma Dashti; Sameer Al-Zenki

1998-01-01

291

Application of multiwall carbon nanotubes-based matrix solid phase dispersion extraction for determination of hormones in butter by gas chromatography mass spectrometry  

Microsoft Academic Search

The multiwall carbon nanotubes (MWCNTs)-based matrix solid phase dispersion (MSPD) was applied for the extraction of hormones, including 17-?-ethinylestradiol, 17-?-estradiol, estriol, 17-?-estradiol, estrone, medroxyprogesterone, progesterone and norethisterone acetate in butter samples. The method includes MSPD extraction of the target analytes from butter samples, derivatization of hormones with heptafluorobutyric acid anhydride–acetonitrile mixture, and determination by gas chromatography–mass spectrometry. The mixture containing

Rui Su; Xinghua Wang; Xu Xu; Ziming Wang; Dan Li; Xin Zhao; Xueyuan Li; Hanqi Zhang; Aimin Yu

2011-01-01

292

Analysis of volatile compounds emitted from fresh Syringa oblata flowers in different florescence by headspace solid-phase microextraction–gas chromatography–mass spectrometry  

Microsoft Academic Search

In this study, a simple and solvent-free method was developed for determination of the volatile compounds from fresh flowers of Syringa oblata using headspace solid-phase microextraction and gas chromatography–mass spectrometry. The SPME parameters were studied, the optimum conditions of a 65?m polydimethylsiloxan\\/divinylbenezene (PDMS\\/DVB), extraction temperature of 25°C and extraction time of 30min were obtained and applied to extraction of the

Zu-Guang Li; Maw-Rong Lee; De-Long Shen

2006-01-01

293

Application of solid-phase microextraction combined with gas chromatography–mass 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 package’s contents. A method for the determination of BHT in water by means of solid-phase microextraction and gas chromatography–mass spectrometry has been

Norma B Tombesi; Hugo Freije

2002-01-01

294

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

Microsoft Academic Search

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

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

2007-01-01

295

Stable carbon isotopic analyses of lignin-derived CuO oxidation products by isotope ratio monitoring-gas chromatography-mass spectrometry (irm-GC-MS)  

Microsoft Academic Search

In this paper, we evaluate compound-specific isotope analyses of lignin reaction products through the combined application of alkaline CuO oxidation and isotope ratio monitoring-gas chromatography-mass spectrometry (irm-GC-MS). Analyses of phenol standards as trimethylsilyl ethers\\/esters by irm-GC-MS yield accurate (±0.5‰) estimates of their isotopic signatures after correcting for added derivative carbon with precisions ?1‰. CuO oxidation of purified lignin polymers yields

Miguel A. Goñi; Timothy I. Eglinton

1996-01-01

296

Development of a headspace solid-phase microextraction–gas chromatography–mass spectrometry method for the identification of odour-causing volatile compounds in packaging materials  

Microsoft Academic Search

A method for the identification of volatile organic compounds in packaging materials is presented in this study. These compounds are formed by thermooxidative degradation during the extrusion coating process in the manufacture of packaging. Headspace solid-phase microextraction (HS-SPME) was used as sample preparation technique prior to the determination of the volatile organic compounds by gas chromatography–mass spectrometry (GC–MS). The effects

Óscar Ezquerro; Begoña Pons; Mar??a Teresa Tena

2002-01-01

297

Determination of trace level chemical warfare agents in water and slurry samples using hollow fibre-protected liquid-phase microextraction followed by gas chromatography–mass spectrometry  

Microsoft Academic Search

A simple and solvent-minimised sample preparation technique based on hollow fibre-protected liquid-phase microextraction was investigated for the gas chromatography\\/mass spectrometric analysis of chemical warfare agents in water and slurry samples. The chemical warfare agents included four nerve agents and a blister agent. Parameters such as extraction solvent, salt concentration, stirring speed and extraction time were optimised using spiked deionised water

Hoi Sim Nancy Lee; Chanbasha Basheer; Hian Kee Lee

2006-01-01

298

Application of headspace solid-phase microextraction and gas chromatography–mass spectrometry for detection of the chemical warfare agent bis(2-chloroethyl) sulfide in soil  

Microsoft Academic Search

A field expedient analytical method for detecting the chemical warfare agent (CWA) sulfur mustard as a soil contaminant was developed using solid-phase microextraction (SPME) and gas chromatography–mass spectrometry (GC–MS). Five commercially available SPME fibers were investigated to determine the optimal fiber, and extraction conditions. Polyacrylate and carbowax–divinylbenzene fiber coatings gave a statistically indistinguishable and best response compared to the other

Gregory L Kimm; Gary L Hook; Philip A Smith

2002-01-01

299

Analysis of biological samples by gas chromatography–mass spectrometry without a reference standard: measurement of urinary 18-hydroxytetrahydro-11-dehydrocorticosterone excretion rate in human subjects  

Microsoft Academic Search

Reference standards for some minor urinary steroid metabolites are sometimes unavailable. We describe a novel procedure to quantitate a urinary steroid metabolite of known structure and mass spectrum, using as a standard a compound which produces ions in common with it and has a similar retention time in gas chromatography–mass spectrometry. The steroid of interest was 18-hydroxy-11-dehydrotetrahydrocorticosterone (18-OH-THA), the major

Loai A Shakerdi; John M. C Connell; Robert Fraser; A. Michael Wallace

2003-01-01

300

Gas chromatography–mass spectrometry analysis of volatile compounds from Houttuynia cordata Thunb after extraction by solid-phase microextraction, flash evaporation and steam distillation  

Microsoft Academic Search

Various sampling techniques including flash evaporation (FE), headspace solid-phase microextraction (HS-SPME) and steam distillation (SD) were compared for the gas chromatography–mass spectrometry of volatile constituents present in Houttuynia cordata Thunb (HCT). 2-Undecanone (22.21%) and houttuynum (7.23%) were predominant components of HCT samples obtained by HS-SPME whereas those levels were 3.95 and 3.60% in the same samples by FE and 25.93

Minmin Liang; Meiling Qi; Changbin Zhang; Shan Zhou; Ruonong Fu; Junxiong Huang

2005-01-01

301

Gas chromatography–mass spectrometry\\/mass spectrometry analysis to determine natural and post-administration levels of oestrogens in bovine serum and urine  

Microsoft Academic Search

A novel analytical approach has been developed and shown to be capable of detecting the isomers of oestradiol in the low ppt (pgmL?1) range in bovine serum and urine. Following extractive derivatisation the analytes were detected as their 3-pentafluorobenzoyl 17-trimethylsilyl ether derivatives by gas chromatography–mass spectrometry\\/mass spectrometry (GC–MS\\/MS), using electron capture negative ion chemical ionisation. The isomers of oestradiol were

S. Biddle; P. Teale; A. Robinson; J. Bowman; E. Houghton

2007-01-01

302

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

303

Identification of plasticizers in medical products by a combined direct thermodesorption–cooled injection system and gas chromatography–mass spectrometry  

Microsoft Academic Search

The combination of a new thermodesorption module with a cooled injection system now provides a powerful system for direct analysis of volatile trace compounds in gaseous, liquid and solid samples by gas chromatography–mass spectrometry (GC–MS). As a cooled injection system is used for the cryofocusing of the desorbed volatiles the GC–MS system still can be used for the regular analysis

Hans Günther Wahl; Andreas Hoffmann; Hans-Ulrich Häring; Hartmut M Liebich

1999-01-01

304

Detection and quantification of fatty acid ethyl esters in meconium by headspace-solid-phase microextraction and gas chromatography–mass spectrometry  

Microsoft Academic Search

Meconium fatty acid ethyl esters (FAEEs) are currently used as biomarkers to detect heavy prenatal alcohol exposure. We introduce a novel technique to quantify FAEEs in meconium using headspace-solid-phase microextraction (HS-SPME) coupled with gas chromatography–mass spectrometry (GC–MS). This method improves on previous approaches by decreasing sample preparation time, eliminating the need for organic solvents, and reducing the required sample size.

J. R. Hutson; K. Aleksa; F. Pragst; G. Koren

2009-01-01

305

Gas chromatography\\/mass spectrometry identification of long-term excreted metabolites of the anabolic steroid 4-chloro-1,2-dehydro-17?-methyltestosterone in humans  

Microsoft Academic Search

The misuse of anabolic steroids by athletes has been banned by sports organizations and is controlled by the analysis of urine samples obtained from athletes using gas chromatography\\/mass spectrometry (GC\\/MS). To extend the retrospectivity of the analytical methods, research is focused on long-term excreted metabolites. Preliminary results concerning the long-term detection of metabolites of the anabolic androgenic steroid 4-chloro-1,2-dehydro-17?-methyltestosterone I

W. Schänzer; S. Horning; G. Opfermann; M. Donike

1996-01-01

306

The identification and simultaneous quantification of 7-hydroxylated metabolites of pregnenolone, dehydroepiandrosterone, 3?,17?-androstenediol, and testosterone in human serum using gas chromatography–mass spectrometry  

Microsoft Academic Search

7-Hydroxy-metabolites of dehydroepiandrosterone (DHEA) and 3?,17?-androstenediol (AD) possess immunomodulatory and neuroprotective properties; therefore, the measurement of these steroids in patients with autoimmune diseases or disturbances in the CNS may be of interest. A gas chromatography–mass spectrometry (GC–MS) method for the determination of 7-hydroxy-metabolites of pregnenolone, DHEA, AD, and testosterone including the parent steroids was applied to serum samples from 12

Martin Hill; Helena Havlíková; Jana Vrbíková; Radmila Kancheva; Lyudmila Kancheva; Vladimír Pouzar; Ivan ?erný; Luboslav Stárka

2005-01-01

307

Gas chromatography mass spectrometry study of hydrogen deuterium exchange reactions of volatile hydrides of As, Sb, Bi, Ge and Sn in aqueous media  

Microsoft Academic Search

The H D exchange processes in MHn or MDn hydrides (M = As, Sb, Bi, n = 3; M = Ge, Sn, n = 4) taking place when they are in contact with H2O or D2O solution at different pH or pD values (interval of pH = [0,13]) have been investigated using gas chromatography mass spectrometry (GC-MS). MHn or MDn

Alessandro D'Ulivo; Zoltan Mester; Juris Meija; Ralph E. Sturgeon

2006-01-01

308

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

Microsoft Academic Search

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

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

2003-01-01

309

Simplified pesticide multiresidues analysis in fish by low-temperature cleanup and solid-phase extraction coupled with gas chromatography\\/mass spectrometry  

Microsoft Academic Search

A simple and fast method for the simultaneous analysis of thiobencarb, deltamethrin and 19 organochlorine pesticide residues in fish by gas chromatography–mass spectrometry was investigated in this study. Samples are extracted with acetonitrile. Most of lipids in the extract are eliminated by low-temperature cleanup, prior to solid-phase extraction cleanup. The lipids extracted from the fish samples were easily removed without

Shubing Chen; Xuejun Yu; Xiaoyu He; Donghua Xie; Yuanmu Fan; Jinfeng Peng

2009-01-01

310

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

Microsoft Academic Search

Investigations concerning the qualitative and quantitative determination of the organic wood preservative component N-cyclohexyl-diazeniumdioxide (HDO) in treated timber were carried out by means of direct thermal desorption–gas chromatography–mass spectrometry (DTD–GC–MS). It could be shown that the identification of HDO in treated pine sapwood (Pinus sylvestris L.) is relatively simple using this analytical technique. Quantification of this active ingredient can be

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

2002-01-01

311

Effects of formic acid hydrolysis on the quantitative analysis of radiation-induced DNA base damage products assayed by gas chromatography\\/mass spectrometry  

Microsoft Academic Search

Gas chromatography\\/mass spectrometry (GC\\/MS-SIM) is an excellent technique for performing both qualitative and quantitative analysis of DNA base damage products that are formed by exposure to ionizing radiation or by the interaction of intracellular DNA with activated oxygen species. This technique commonly uses a hot formic acid hydrolysis step to degrade the DNA to individual free bases. However, due to

Steven G. Swarts; George S. Smith; Lan Miao; Kenneth T. Wheeler

1996-01-01

312

Simultaneous determination of selegiline and desmethylselegiline in human body fluids by headspace solid-phase microextraction and gas chromatography–mass spectrometry  

Microsoft Academic Search

A method for the simultaneous determination of selegiline and its metabolite, desmethylselegiline, in human whole blood and urine is presented. The method, which combines a fiber-based headspace solid-phase microextraction (SPME) technique with gas chromatography–mass spectrometry (GC–MS), required optimization of various parameters (e.g., salt additives, extraction temperatures, extraction times and the extraction properties of the SPME fiber coatings). Pargyline was used

Ayako Kuriki; Takeshi Kumazawa; Xiao-Pen Lee; Chika Hasegawa; Mitsuru Kawamura; Osamu Suzuki; Keizo Sato

2006-01-01

313

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

Microsoft Academic Search

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

Mehdi Jalali-Heravi; Behrooz Zekavat; Hassan Sereshti

2007-01-01

314

Use of pyrolysis-gas chromatography\\/mass spectrometry to study environmental pollution caused by synthetic polymers: a case study: the Ravenna Lagoon  

Microsoft Academic Search

Pyrolysis-gas chromatography\\/mass spectrometry (Py-GC\\/MS) has been applied to study the composition of synthetic polymers in sediments and nepheloid layers of Pialassa Baiona, a coastal lagoon located north-east the city of Ravenna (Italy), in the proximity of an industrial area. To this purpose sample pyrograms are compared with pyrograms of standard synthetic polymers, namely poly(vinyl chloride) (PVC), poly(vinyl acetate) (PVA), polystyrene

Daniele Fabbri

2001-01-01

315

Determination of methadone and its metabolites EDDP and EMDP in human hair by headspace solid-phase microextraction and gas chromatography–mass spectrometry  

Microsoft Academic Search

A simple method for analysis of methadone and its two main metabolites EDDP and EMDP in hair was developed using automatic headspace solid-phase microextraction (HS-SPME) at a multipurpose sampler and gas chromatographymass spectrometry with electron impact ionization and selected ion monitoring (GC–MS-SIM). The washed hair pieces were digested in the closed headspace vial in 1 ml 1 M

Frank Sporkert; Fritz Pragst

2000-01-01

316

Rapid identification and quantification of methamphetamine and amphetamine in hair by gas chromatography\\/mass spectrometry coupled with micropulverized extraction, aqueous acetylation and microextraction by packed sorbent  

Microsoft Academic Search

We developed a rapid identification and quantification method for the toxicological analysis of methamphetamine and amphetamine in human hair by gas chromatography\\/mass spectrometry coupled with a novel combination of micropulverized extraction, aqueous acetylation and microextraction by packed sorbent (MEPS) named MiAMi–GC\\/MS. A washed hair sample (1–5mg) was micropulverized for 5min in a 2mL plastic tube with 250?L of water. An

Hajime Miyaguchi; Yuko T. Iwata; Tatsuyuki Kanamori; Kenji Tsujikawa; Kenji Kuwayama; Hiroyuki Inoue

2009-01-01

317

Reproducibility of gas chromatography–mass spectrometry measurements of 2H labeling of water: Application for measuring body composition in mice  

Microsoft Academic Search

Deuterium-labeled water (2H2O) has emerged as a novel isotope tracer. Following the administration of 2H2O, it is possible to study the dynamics of carbohydrate, protein, lipid, and DNA and to determine body composition. Those studies require reliable measurements of the 2H labeling of water. Although simple gas chromatography–mass spectrometry (GC–MS) methods have been developed for measuring the 2H enrichment of

Brendan J. McCabe; Ilya R. Bederman; Colleen Croniger; Carrie Millward; Christopher Norment; Stephen F. Previs

2006-01-01

318

[Alteration of polyol metabolism in glomeruli of streptozotocin diabetic rats--analysis by gas chromatography-mass spectrometry].  

PubMed

The purpose of the present study is to determine polyols and sugars in glomeruli obtained from streptozotocin (STZ) diabetic rats. Sixty milligram per kg body weight of STZ was injected to Sprague-Dawley male rats and then the animals were sacrificed 4 and 12 weeks after the injection. One group of STZ diabetic rats was treated with 8-14 units of NPH insulin for 3 weeks. Glomeruli were isolated by sieving methods. The concentration of polyols and sugars was measured by gas chromatography mass spectrometry. The levels of glucose, sorbitol, fructose, mannose, ribitol and erythritol in the glomeruli were significantly higher in 4- or 12-week diabetic rats than those in control rats, whereas the level of scyllo-inositol was decreased. In insulin treated 4-week diabetic rats, the levels of all polyols but scyllo-inositol were significantly decreased compared with untreated diabetic rats. The level of myo-inositol in glomeruli of 12-week diabetic rats was significantly higher than those of control rats, whereas that of erythritol was decreased. The urinary N-acetyl glucosaminidase activity as well as creatinine clearance was increased in 4- and 12-week diabetic rats. Urinary protein was also increased in 12-week diabetic rats. These findings suggest that the alterations of polyol metabolism in glomeruli of diabetes may play an important role in the pathogenesis and/or progression of diabetic nephropathy. It is likely that treatment with insulin improves the alteration of polyol metabolism in the glomeruli in early stages of diabetes. PMID:2142967

Wang, L N; Fukui, M; Tomino, Y; Koide, H

1990-04-01

319

Determination of volatile components in ginger using gas chromatography-mass spectrometry with resolution improved by data processing techniques.  

PubMed

Ginger is widely used as either a food product or an herbal medicine in the world. In this paper, a method was developed for determining volatile components in essential oils from both dried and fresh ginger by use of gas chromatography-mass spectrometry (GC-MS) and chemometric approaches. With the resolution improvement by chemometric methods upon two-dimensional data from GC-MS, the drifting baseline can be corrected. In addition, the peak purity can be assessed and the number of chemical components and their stepwise elution in the peak clusters can be identified. The peak clusters investigated are then resolved into pure chromatograms and related mass spectra for each of the components involved. Finally, with the pure chromatograms and related mass spectra obtained, the chemical components can be qualitatively identified based on the similarity searches in the MS databases and the chromatographic retention times. Quantitative determination can be conducted using the overall volume integration approach. The results showed that 140 and 136 components were separated and that 74 and 75 of them were tentatively identified, which accounted for about 62.82 and 47.11% of the total relative content for dried and fresh ginger, respectively. In comparison with the chromatographic fingerprints of essential oils from dried and fresh ginger, 60 of the volatile components determined match with each other. The study demonstrated that the use of chemometric resolution based on two-dimensional data can mathematically enhance the separation ability of GC-MS and assist qualitative and quantitative determination of chemical components separated from complicated practical systems such as foods, herbal medicines, and environmental samples. PMID:15478995

Gong, Fan; Fung, Ying-Sing; Liang, Yi-Zeng

2004-10-20

320

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; González-Vila, Francisco J; González-Gaitano, Gustavo; García-Mina, José M

321

Optimization of pressurized liquid extraction and purification conditions for gas chromatography-mass spectrometry determination of UV filters in sludge.  

PubMed

This work presents an effective sample preparation method for the determination of eight UV filter compounds, belonging to different chemical classes, in freeze-dried sludge samples. Pressurized liquid extraction (PLE) and gas chromatography-mass spectrometry (GC-MS) were selected as extraction and determination techniques, respectively. Normal-phase, reversed-phase and anionic exchange materials were tested as clean-up sorbents to reduce the complexity of raw PLE extracts. Under final working conditions, graphitized carbon (0.5 g) was used as in-cell purification sorbent for the retention of co-extracted pigments. Thereafter, a solid-phase extraction cartridge, containing 0.5 g of primary secondary amine (PSA) bonded silica, was employed for off-line removal of other interferences, mainly fatty acids, overlapping the chromatographic peaks of some UV filters. Extractions were performed with a n-hexane:dichloromethane (80:20, v:v) solution at 75°C, using a single extraction cycle of 5 min at 1500 psi. Flush volume and purge time were set at 100% and 2 min, respectively. Considering 0.5 g of sample and 1 mL as the final volume of the purified extract, the developed method provided recoveries between 73% and 112%, with limits of quantification (LOQs) from 17 to 61 ng g(-1) and a linear response range up to 10 ?g g(-1). Total solvent consumption remained around 30 mL per sample. The analysis of non-spiked samples confirmed the sorption of significant amounts of several UV filters in sludge with average concentrations above 0.6 ?g g(-1) for 3-(4-methylbenzylidene) camphor (4-MBC), 2-ethylhexyl-p-methoxycinnamate (EHMC) and octocrylene (OC). PMID:21144528

Negreira, N; Rodríguez, I; Rubí, E; Cela, R

2010-11-19

322

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

323

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; Püttmann, W

2012-12-13

324

Comparison of four extraction methods for the determination of fungicide residues in grapes through gas chromatography-mass spectrometry.  

PubMed

Four different methods for simultaneous extraction of vinclozolin, dichlofluanid, penconazole, captan, quinoxyfen, fluquinconazol, boscalid and pyraclostrobin from grapes were optimized and further tested. Microwave assisted extraction (MAE), matrix solid-phase dispersion (MSPD), solid-liquid extraction (SLE) and QuEChERS were compared in terms of their limits of detection and quantification and recoveries. For MAE, MSPD and ethyl acetate extraction, the optimal conditions were optimized by using experimental designs. The analysis was performed using gas chromatography-mass spectrometry in the selected ion monitoring mode (GC-MS, SIM). The proposed methods showed good sensitivity, limits of quantification were lower than MRLs and precision (expressed as relative standard deviation) ranged from 2.9 to 11.1%. The recoveries obtained from MAE, MSPD, SLE and QuEChERS were in the range 78-100%, 66-102%, 58-88% and 68-96%, respectively. In addition, the four methods were compared in two ways: by means of calibration curves obtained with 10 fortified samples in the studied range of concentrations and by the application of statistical tests such as Levene's test (to study variance homogeneity), ANOVA and Tukey's test (in case of Levene's test was satisfactory) for the assessment of the information obtained in the analysis of real samples. Both ways of comparison led to the same results: no differences between the four methods for the extraction of vinclozolin, dichofluanid, quinoxyfen, fluquinconazol and pyraclostrobin were found. However, there were differences for the analysis of captan, boscalid and penconazole. PMID:23182285

Lagunas-Allué, L; Sanz-Asensio, J; Martínez-Soria, M T

2012-11-06

325

Trace-level measurement of complex combustion effluents and residues using multidimensional gas chromatography-mass spectrometry (MDGC-MS).  

PubMed

The identification and quantitation of non-method-specific target analytes have greater importance with respect to EPA's current combustion strategy. The risk associated with combustion process emissions must now be characterized. EPA has recently released draft guidance on procedures for the collection of emissions data to support and augment site-specific risk assessments (SSRAs) as part of the hazardous waste incineration permitting process. This guidance includes methodology for quantifying total organic (TO) emissions as a function of compound volatility. The ultimate intent is to compare the amount of organic material identified and quantified by target analyte-specific methodologies to organic emissions quantified by the TO methodology. The greater the amount accounted for by the target analyte-specific methodologies, the less uncertainty may be associated with the SSRAs. A limitation of this approach is that the target analyte-specific methodologies do not routinely quantify compounds of low toxicological interest; nor do they target products of incomplete combustion (PICs). Thus, the analysis can miss both toxic and non-toxic compounds. As a result, it is unknown whether the uncharacterized fraction of the TO emission possesses toxic properties. The hypothesis that we propose to test is that organic emissions and organics extracted from particulate matter (PM) are more complex than standard GC-MS-based instrumentation can currently measure. This complexity can affect quantitation for toxic compounds, thereby potentially affecting risk assessments. There is a pressing need to better characterize these organic emissions from hazardous waste incinerators and PM extracts from various other combustion sources. We will demonstrate that multidimensional gas chromatography-mass spectrometry (MDGC-MS) procedures significantly improve chromatographic separation for complex environmental samples. Sequential repetitive heart-cutting MDGC, with coupled mass spectrometry will be shown to be a complete analysis technique. The ability of this technique to disengage components from complex mixtures taken from hazardous and municipal waste incinerators will be shown. PMID:12099499

Striebich, Richard C; Rubey, Wayne A; Klosterman, Joy R

2002-01-01

326

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

327

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

PubMed

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 (IC?? 19.97 ± 2.67 ?g/ml, mean ± SEM, n?=?4). Extracts had similar potency to Trolox (IC?? 12.78 ± 1.82 ?g/ml), but were less potent than honeybee propolis (IC?? 5.90 ± 0.62 g/ml) or gallic acid (IC?? 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. PMID:21347735

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

2011-02-24

328

Chemometric Analysis of Gas ChromatographyMass 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

329

Simultaneous assay of cocaine, heroin and metabolites in hair, plasma, saliva and urine by gas chromatography-mass spectrometry.  

PubMed

As part of an ongoing research program on the development of drug detection methodology, we developed an assay for the simultaneous measurement of cocaine, heroin and metabolites in plasma, saliva, urine and hair by solid-phase extraction (SPE) and gas chromatography-mass spectrometry (GC-MS). The analytes that could be measured by this assay were the following: anhydroecgonine methyl ester; ecgonine methyl ester;. ecgonine ethyl ester; cocaine; cocaethylene; benzoylecgonine; cocaethylene; norcocaethylene; benzoylnorecgonine; codeine; morphine; norcodeine; 6-acetylmorphine; normorphine; and heroin. Liquid specimens were diluted, filtered and then extracted by SPE. Additional handling steps were necessary for the analysis of hair samples. An initial wash procedure was utilized to remove surface contaminants. Washed hair samples were extracted with methanol overnight at 40 degrees C. Both wash and extract fractions were collected, evaporated and purified by SPE. All extracts were evaporated, derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane (TMCS) and analyzed by GC-MS. The limit of detection (LOD) for cocaine, heroin and metabolites in biological specimens was approximately 1 ng/ml with the exception of norcodeine, normorphine and benzoylnorecgonine (LOD = 5 ng/ml). The LOD for cocaine, heroin and metabolites in hair was approximately 0.1 ng/mg of hair with the exception of norcodeine (LOD = 0.3 ng/mg) and normorphine and benzoylnorecgonine (LOD = 0.5 ng/mg). Coefficients of variation ranged from 3 to 26.5% in the hair assay. This assay has been successfully utilized in research on the disposition of cocaine, heroin and metabolites in hair, plasma, saliva and urine and in treatment studies. PMID:7866518

Wang, W L; Darwin, W D; Cone, E J

1994-10-14

330

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

PubMed

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

Dekker, M H; Piersma, T; Damsté, J S

2000-05-01

331

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

PubMed

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

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

2011-08-05

332

Assessment of the degradation of polyurethane foams after artificial and natural ageing by using pyrolysis-gas chromatography/mass spectrometry and headspace-solid phase microextraction-gas chromatography/mass spectrometry.  

PubMed

Polyurethane foams are widely present in museum collections either as part of the artefacts, or as a material for their conservation. Unfortunately many of PU foam artefacts are in poor condition and often exhibit specific conservation issues. Their fast thermal and photochemical degradations have been the aim of previous researches. It is now accepted that hydrolysis predominates for polyester-based polyurethane PU(ES) whereas oxidation is the principal cause of degradation for polyether-based polyurethane PU(ET) variety. Only a few studies have been devoted to volatile organic compounds (VOCs) emitted by polyurethanes and, to our knowledge, none were performed on polyurethane foams by using headspace-solid phase microextraction (HS-SPME). The objective of the work described here is to assess the impact of some environmental factors (humidity, temperature and daylight) on the degradation of PU foams by evaluating their volatile fractions. We investigated morphological changes, polymerized fractions and volatile fractions of (i) one modern produced PU(ES) foam and one modern PU(ET) foam artificially aged in different conditions as well as (ii) four naturally aged foams collected from various daily life objects and selected for the representativeness of their analytical data. Characterization procedure used was based on attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and non-invasive headspace solid-phase microextraction coupled with gas chromatography and mass spectrometry (HS-SPME-GC/MS). In this paper, the formation of alcohol and acid raw products for PU(ES) and glycol derivatives for PU(ET) during natural and artificial ageing is confirmed. These main products can be considered as degradation markers for PU foams. Results show that artificial and natural ageing provide similar analytical results, and confirm that the dominant degradation paths for PU(ES) and for PU(ET) are hydrolysis and photo-oxidation, respectively. Lastly, we highlight that non-invasive HS-SPME-GC/MS analysis allows to distinguish between PU(ES) and PU(ET) at any point of their degradations. PMID:21645901

Lattuati-Derieux, A; Thao-Heu, S; Lavédrine, B

2011-05-17

333

Method development and validation for determining 1,3-butadiene in human blood by gas chromatography-mass spectrometry and head-space gas chromatography.  

PubMed

To develop a simple, validated method for identifying and quantifying 1,3-butadiene (BD) in human blood by gas chromatography-mass spectrometry (GC-MS) and head-space gas chromatography (HS-GC). BD was identified by GC-MS and HS-GC, and quantified by HS-GC. The method showed that BD had a good linearity from 50 to 500 microg/mL (r > 0.99). The limits of detection and quantification were 10 microg/mL and 50 microg/mL, respectively. Both the intra-day precision and inter-day precision were < 6.08%, and the accuracy was 96.98%-103.81%. The method was applied to an actual case, and the concentration of BD in the case was 242 microg/mL in human blood. This simple method is found to be useful for the routine forensic analysis of acute exposure to BD. PMID:23930504

Zhang, Su-Jing; Shen, Bao-Hua; Zhuo, Xian-Yi

2013-04-01

334

Determination of sucrose esters of fatty acids in food additive premixes by gas chromatography and confirmation of identity by gas chromatography/mass spectrometry.  

PubMed

A gas chromatographic (GC) method was developed for the determination of sucrose monoesters of fatty acids (mono-SuE) and sucrose acetate isobutyrate (SAIB) in food additive premixes. Mono-SuE and SAIB fractions were prepared by column chromatography with either a C8 or a silica gel solid-phase extraction column. The mono-SuE fraction was acetylated and applied to a wide-bore GC column (0.53 mm x 15 m) by splitless injection for determination. The SAIB fraction was applied to the GC column without derivatization. Gas chromatography/mass spectrometry was used to confirm the identity of GC peaks. The detection limits for mono-SuE and SAIB were 0.005 and 0.01%, respectively. Mono-SuE (C12, C14, C16, C18, and C18:1) and SAIB were found in commercial food additive premixes and some foods. PMID:11324617

Uematsu, Y; Hirata, K; Suzuki, K; Iida, K; Kan, T; Saito, K

335

Analysis of polysulfides in drinking water distribution systems using headspace solid-phase microextraction and gas chromatography-mass spectrometry.  

PubMed

Sulfide and polysulfides are strong nucleophiles and reducing agents that participate in many environmentally significant processes such as the formation of sulfide minerals and volatile organic sulfur compounds. Their presence in drinking water distribution systems are of particular concern and need to be assessed, since these species consume disinfectants and dissolved oxygen, react with metal ions to produce insoluble metal sulfides, and cause taste and odour problems. The analysis of sulfide and polysulfides in drinking water distribution systems is challenging due to their low concentrations, thermal instability and their susceptibility to undergo oxidation and disproportionation reactions. This paper reports on the development and optimisation of a rapid, simple, and sensitive method for the determination of sulfide and polysulfides in drinking water distribution systems. The method uses methyl iodide to derivatize sulfide and polysulfides into their corresponding dimethyl(poly)sulfides, which are then extracted using solid-phase microextraction in the headspace mode and analysed by gas chromatography-mass spectrometry. Good sensitivity was achieved for the analysis of dimethyl(poly)sulfides, with detection limits ranging from 50 to 240 ng L(-1). The method also demonstrated good precision (repeatability: 3-7%) and good linearity over two orders of magnitude. Matrix effects from raw drinking water containing organic carbon (3.8 mg L(-1)) and from sediment material from a drinking water distribution system were shown to have no interferences in the analysis of dimethyl(poly)sulfides. The method provides a rapid, robust, and reliable mean to analyse trace levels of sulfides and polysulfides in aqueous systems. The new method described here is more accessible and user-friendly than methods based on closed-loop stripping analysis, which have been traditionally used for the analysis of these compounds. The optimised method was used to analyse samples collected from various locations in a drinking water distribution system. Some of the samples were shown to contain inorganic polysulfides, and their presence was associated with high sediment density in the system and the absence of disinfectant residual in the bulk water. PMID:20708191

Kristiana, Ina; Heitz, Anna; Joll, Cynthia; Sathasivan, Arumugam

2010-07-22

336

Impurity analysis of pure aldrin using heart-cut multi-dimensional gas chromatography-mass spectrometry.  

PubMed

Identification and quantification of related-structure impurity is a research focus in the purity assessment of organic compounds. Determination of the purity value and uncertainty assessment are also important in the metrological research. A method for the determination of related-structure impurity in pure aldrin sample has been developed by using heart-cut multi-dimensional gas chromatography-mass spectrometry (MDGC/MS). Compared to the traditional one-dimensional (1-D) GC system, the two separated columns in the MDGC/MS system can effectively reduce co-elution, enhance separation capability, and thus improve detectability of the trace-level impurities. In addition, MDGC/MS system was simultaneously equipped with flame ionization detector (FID) or electron capture detector (ECD) in the first GC unit and mass spectrometry (MS) detector in the second GC unit. Therefore, accurate quantitative results of the trace-level impurities can be easily achieved by isolation of principal component to the second dimension column using "heart-cut" process. The mass fraction of related-structure impurities in aldrin samples obtained using MDGC/MS system ranged from 6.8×10?³ mg g?¹ to 26.47 mg g?¹ with five orders of magnitude, which is hard to be realized by mean of the 1-D GC. Excellent linearity with correlation coefficients of above 0.999 was achieved for each impurity analysis over a wide range of concentrations. Limits of quantification (LOQ) varied from 250 ng g?¹ to 330 ng g?¹ for FID, and from 1.0 ng g?¹ to 2.0 ng g?¹ detected by ECD. The combined standard uncertainty (u(c)) was lower than 0.37 mg g?¹ and 0.040 mg g?¹ detected using FID and ECD, respectively. Therefore, performance characterization of MDGC/MS used in the study is fit for quantification analysis of trace-level impurity. These results demonstrate that the MDGC/MS is extremely suitable for the purity assessment of organic compounds with medium structural complexity and low polarity. PMID:23332869

Li, Xiaomin; Dai, Xinhua; Yin, Xiong; Li, Ming; Zhao, Yingchen; Zhou, Jian; Huang, Ting; Li, Hongmei

2013-01-03

337

Seasonal variations of particle-associated nitrosamines by gas chromatography-mass spectrometry in the atmospheric environment of Zonguldak, Turkey.  

PubMed

A gas chromatography-mass spectrometry method has been proposed for the determination of low-level mutagenic and carcinogenic nitrosamines in particulate matter. The method includes the collection of particulate matters (PM2.5 and PM10) using a dichotomous Partisol 2025 sampler and extraction of the compounds from aqueous solution with dichloromethane/2-propanol after sonication with a slightly basic water solution prior to their GC-MS analysis in electron impact mode. The obtained recoveries of nitrosamines ranged from 92.4 to 99.2 %, and the precision of this method, as indicated by the relative standard deviations, was within the range of 0.95-2.46?%. The detection limits obtained from calculations using the GC-MS results based on S/N?=?3 were found within the range from 4 to 22 pg/m(3). The predominant nitrosamines determined in particulate matter were N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosodibutylamine and N-nitrosomorpholine. Furthermore, N-mono- and dinitrosopiperazine and N-nitrosoethylbutylamine were also determined. N-dinitrosopiperazine was detected in PM2.5 samples at the highest concentrations of up to 22.85 ng/m(3) and in PM2.5-10 samples at concentrations up to 7.60 ng/m(3) in winter, whereas it was found in PM2.5 samples up to 5.15 ng/m(3) and in PM2.5-10 samples up to 3.12 ng/m(3) in summer. The total concentrations of nitrosamines were up to 161.4 ng/m(3) in fine and 53.90 ng/m(3) in coarse fractions in winter, whereas in summer were up to 35.24 and 12.60 ng/m(3), respectively. The concentration levels of nitrosamines fluctuated significantly within a year, with higher means and peak concentrations in the winter compared to that in the summertime. The seasonal variations of particle-associated nitrosamine concentrations were investigated together with their relationships with meteorological parameters using Pearson's correlation analysis in the winter and summer periods. Analysis of variance was used to determine which concentrations of nitrosamines were statistically different from one another and, together with meteorological parameters and discriminant analysis, was used to classify the particle samples by particle size according to seasons. The classification results of the particle samples in different seasons were very satisfactory, allowing 99.5 % of cases to be correctly grouped. PMID:23657717

Akyüz, Mehmet; Ata, Sevket

2013-05-09

338

Validation of a gas chromatography/mass spectrometry method for the quantification of aerosolized Jet Propellant 8.  

PubMed

Jet Propellant 8 (JP-8) jet fuel is a kerosene-based fuel containing hundreds of hydrocarbons used by the military in NATO countries. Previous rodent inhalation studies carried out with aerosolized JP-8 never evaluated the exposure chamber atmosphere. For this reason, our laboratory developed an analytical method, with an accuracy of better than 80% and precision of better than 20%, for JP-8 aerosol and vapor samples using gas chromatography/mass spectrometry (GC/MS). A method was developed for quantification of selected individual components of JP-8 and for the total amount of JP-8 in aerosolized fuel. A 34 component surrogate hydrocarbon mixture (SHM) was developed and used for simultaneous analysis of the individual components. Three separate runs containing a standard curve and five replicates each at the selected concentrations were analyzed for both the SHM and neat JP-8. The resulting interday accuracy (100-percent relative error) and precision (relative standard deviation) values for the SHM were 86.5% or better and 8.0% or better, respectively. The intraday accuracy and precision values ranged from 99.29% to 84.50% and 0.97% to 12.4%, respectively. For the total amount of JP-8 in aerosol and vapor, the interday accuracy was 83.7% or better and interday precision was 7.0% or better. The intraday accuracy and precision values ranged from 94.8% to 80.4% and 2.4% to 10.5%, respectively. We then used this method to analyze samples collected from an inhalation chamber. From the data obtained, we are able to account for approximately 40-44% of the mass of the aerosol portion and 68-70% of the mass of the vapor portion. The aerosol represented 6-10% of the total mass of the aerosolized JP-8 fuel with the remaining portion being the vapor. From these experiments individual components were identified for further in vivo and in vitro toxicological testing. PMID:16233866

Dietzel, Katherine D; Campbell, Jerry L; Bartlett, Michael G; Witten, Mark L; Fisher, Jeffrey W

2005-10-05

339

Monitoring sulfur mustard exposure by gas chromatography-mass spectrometry analysis of thiodiglycol cleaved from blood proteins.  

PubMed

A gas chromatography-mass spectrometry method for determining exposure to the chemical warfare agent 2,2'-dichlorodiethyl sulfide (sulfur mustard; HD) has been developed. The technique is based upon quantitating thiodiglycol (TDG) released from blood protein adducts that are formed upon exposure to HD. Protein was precipitated from plasma, whole blood, or packed red blood cells (RBCs) and then treated with sodium hydroxide to liberate protein-bound TDG. The TDG was derivatized with pentafluorobenzoyl chloride that enabled sensitive detection by negative-ion chemical ionization. Octadeuterothiodiglycol was used as an internal standard. Exposure of human plasma to HD (25 nM to 400 nM) resulted in a linear relationship (r2 = 0.9995) between HD concentration and released TDG levels with means ranging from 2.0 to 38 pg/mg protein. The coefficients of variation expressed as a percentage for the data points ranged from 2 to 11.5%. The application of this procedure was demonstrated in two HD animal exposure models. African green monkeys (Chlorocebus aethiops) were exposed intravenously to 1 mg/kg HD, and TDG levels in blood samples were analyzed out to 45 days post-exposure. Mean TDG levels were determined to be 220 pg/mg protein on day 1 and declined to 10 pg/mg protein on day 45. Yorkshire cross pigs (Sus scrofa) were cutaneously exposed to neat liquid HD, and TDG levels in plasma were determined out to 21 days following exposure. Mean TDG levels were found to be 60 pg/mg protein on day one and decreased to an average of 4 pg/mg protein on day 21. The data from this study indicate that the assay is sensitive and provide a relatively simple approach to assay TDG cleaved from blood proteins at relatively long time frames (21-45 days) after HD exposure. The utility of the method has been demonstrated in vivo in a non-human primate and pig HD exposure model. PMID:15239847

Capacio, Benedict R; Smith, J R; DeLion, Michael T; Anderson, Dana R; Graham, John S; Platoff, Gennady E; Korte, William D

340

Simultaneous quantitative determination of amphetamines, ketamine, opiates and metabolites in human hair by gas chromatography/mass spectrometry.  

PubMed

A gas chromatography/mass spectrometry (GC/MS) method was developed and validated for the determination of common drugs of abuse in Asia. The method was able to simultaneously quantify amphetamines (amphetamine; AP, methamphetamine; MA, methylenedioxy amphetamine; MDA, methylenedioxymeth mphetamine; MDMA, methylenedioxy ethylamphetamine; MDEA), ketamine (ketamine; K, norketamine; NK), and opiates (morphine; MOR, codeine; COD, 6-acetylmorphine; 6-AM) in human hair. Hair samples (25 mg) were washed, cut, and incubated overnight at 25 degrees C in methanol/trifluoroacetic acid (methanol/TFA). The samples were extracted by solid-phase extraction (SPE), derivatized using heptafluorobutyric acid anhydride (HFBA) at 70 degrees C for 30 min, and the derivatives were analyzed by electron ionization (EI) GC/MS in selected ion monitoring mode. Confirmation was accomplished by comparing retention times and the relative abundances of selected ions with those of standards. Deuterated analogs of the analytes were used as internal standards for quantification. Calibration curves for ten analytes were established in the concentration range 0.1-10 ng/mg with high correlation coefficients (r2 > 0.999). The intra-day and inter-day precisions were within 12.1% and 15.8%, respectively. The intra-day and inter-day accuracies were between -8.7% and 10.7%, and between -5.9% and 13.8%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) obtained were 0.03 and 0.05 ng/mg for AP, MA, MDA, MDMA and MDEA; 0.05 and 0.08 ng/mg for K, NK, MOR and COD; and 0.08 and 0.1 ng/mg for 6-AM. The recoveries were above 88.6% for all the compounds, except K and NK which were in the range of 71.7-72.7%. Eight hair samples from known polydrug abusers were examined by this method. These results show that the method is suitable for broad-spectrum drug testing in a single hair specimen. PMID:18288687

Wu, Ya-Hsueh; Lin, Keh-Liang; Chen, Su-Chin; Chang, Yan-Zin

2008-01-01

341

Determination of alkyl anilines and alkyl pyridines in solvent refined coal distillates and aqueous extracts by gas chromatography/mass spectrometry  

SciTech Connect

Derivatization with acetic anhydride in aqueous media coupled with capillary gas chromatography/mass spectrometry was used to distinguish alkyl anilines from alkyl pyridines. By use of this approach aniline, C-1 anilines, and C-2 anilines, as well as lesser quantities of C-2 pyridines and C-3 pyridines, were positively identified in a solvent refined coal (SRC-II) blended distillate and in an aqueous extract of the distillate. The extraction procedure and acetylation conditions employed were examined in detail and found suitable for quantitative analysis when combined with capillary gas chromatography.

Felice, L.T.

1982-05-01

342

Trace level detection of chlorinated paraffins in biological and environmental samples, using gas chromatography/mass spectrometry with negative-ion chemical ionization.  

PubMed

A method is described for detection of chlorinated paraffins (CPs) in biological and environmental samples. Sample preparation includes sulfuric acid treatment followed by adsorption chromatography on alumina, which yields the CPs in one fraction that is almost free of interfering material. Using gas chromatography/mass spectrometry with negative-ion chemical ionization, the limit of detection is 5 ng (corresponding to the lower ppb range). CP levels of 30 ppm, 200 ppb, and 5 ppb were found in sewage sludge, human fat, and sediment, respectively. PMID:4019363

Schmid, P P; Müller, M D

343

Constituents of Justicia pectoralis Jacq. 2. Gas chromatography/mass spectrometry of simple coumarins, 3-phenylpropionic acids and their hydroxy and methoxy derivatives.  

PubMed

The analysis of extracts from the South American plant Justicia pectoralis Jacq. permitted the identification, among other compounds, of coumarin, dihydrocoumarin, umbelliferone and 3-(2-hydroxyphenyl)propionic acid by gas chromatography/mass spectrometry (GC/MS); the acids and phenolic compounds were derivatized with diazomethane. GC/MS of simple coumarins, phenylpropionic acids and their hydroxylated isomers was performed after derivatization through methylation and trimethylsilylation; these results may be useful for the identification and quantification of these compounds in other biological materials. PMID:3382796

de Vries, J X; Tauscher, B; Wurzel, G

1988-04-15

344

Determination of extracellular and intracellular enrichments of [1- 13C]-?-ketoisovalerate using enzymatically converted [1- 13C]-valine standardization curves and gas chromatography–mass spectrometry  

Microsoft Academic Search

We report a validated method for the determination of extra- and intracellular [1-13C]-?-ketoisovalerate ([1-13C]-KIV) enrichments by gas chromatography–mass spectrometry. Standardization curves were prepared by enzymatic oxidation of [1-13C]-valine enriched standards of known composition. Slopes of [1-13C]-valine standardization curves (mean±SD: 0.99±0.02, n=5) and [1-13C]-KIV standardization curves (mean±SD: 0.98±0.01, n=7) were not significantly different. The method was applied for the determination of

W. Kulik; C. Jakobs; K. de Meer

1999-01-01

345

Evaluation of chemical indicators for monitoring freshness of food and determination of volatile amines in fish by headspace solid-phase microextraction and gas chromatography-mass spectrometry  

Microsoft Academic Search

A headspace solid-phase microextraction and gas chromatography–mass spectrometric (HS-SPME-GC-MS) method was developed to monitor methylamine (MA), dimethylamine (DMA) and trimethylamine (TMA) in fish. The alkylamines were extracted using carboxen\\/divinylbenzene\\/polydimethylsiloxane (CAR\\/DVB\\/ PDMS) fibres at 25 °C and exposure time of 5 min. Calibration curves showed good linearity in the concentration range of 0.5–10 ?g ml?1 and the corresponding coefficients of correlation were all above 0.99.

Serena T. Chan; Michael W. Y. Yao; Y. C. Wong; Timothy Wong; C. S. Mok; Della W. M. Sin

2006-01-01

346

Gas chromatography–mass spectrometry assay for the simultaneous quantification of drugs of abuse in human placenta at 12th week of gestation  

Microsoft Academic Search

We describe the development and validation of a method for the quantification of drugs of abuse, using gas chromatography–mass spectrometry (GC\\/MS), in human placenta. Concentration ranges covered were 5–500ng\\/g for amphetamine, methamphetamine, MDMA, methadone, cocaine, benzoylecgonine, cocaethylene, morphine, 11-nor-9-carboxy-delta-9-tetrahydrocannabinol, nicotine, and cotinine. Intra-assay and inter-assay imprecisions were less than 15.7% for lower quality control samples and less than 14.9% for

Xavier Joya; Mitona Pujadas; María Falcón; Ester Civit; Oscar Garcia-Algar; Oriol Vall; Simona Pichini; Aurelio Luna; Rafael de la Torre

2010-01-01

347

Dynamic solid phase microextraction for sampling of airborne sarin with gas chromatography-mass spectrometry for rapid field detection and quantification.  

PubMed

A portable dynamic air sampler and solid phase microextraction were used to simultaneously detect, identify, and quantify airborne sarin with immediate analysis of samples using a field portable gas chromatography-mass spectrometry system. A mathematical model was used with knowledge of the mass of sarin trapped, linear air velocity past the exposed sampling fiber, and sample duration allowing calculation of concentration estimates. For organizations with suitable field portable instrumentation, these methods are potentially useful for rapid onsite detection and quantification of high concern analytes, either through direct environmental sampling or through sampling of air collected in bags. PMID:15352721

Hook, Gary L; Jackson Lepage, Carmela; Miller, Stephen I; Smith, Philip A

2004-08-01

348

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

Microsoft Academic Search

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

Roland F. Staack; Hans H. Maurer

2004-01-01

349

Application of high-temperature gas chromatography-mass spectrometry to the investigation of glycosidically bound components related to cashew apple (Anacardium occidentale L. Var. Nanum) volatiles.  

PubMed

Free and bound volatile components of a Brazilian cashew apple variety (Anacardium occidentale L. var. nanum) were obtained by simultaneous distillation-extraction (SDE) and XAD-2 adsorption. According to gas chromatography-mass spectrometry (GC-MS) analyses and retention indices, 62 free volatile constituents were characterized and quantified. They were esters (40%), terpenes (20%), hydrocarbons (14%), fatty acids (9%), aldehydes (8%), alcohols (3%), lactones (3%), ketones (1%), phenols (1%), and norisoprenoids (1%). The glycosidically bound volatile precursors were analyzed by high-temperature GC-MS, after room temperature silylation. Several conjugated alcohols and cinnamic acids were detected and reported as cashew apple glycosyl constituents for the first time. PMID:10775367

Bicalho, B; Pereira, A S; Aquino Neto, F R; Pinto, A C; Rezende, C M

2000-04-01

350

The simultaneous separation and determination of chloropropanols in soy sauce and other flavoring with gas chromatography-mass spectrometry in negative chemical and electron impact ionization modes  

Microsoft Academic Search

Both gas chromatography-mass spectrometry in electron ionization (GC-MS-EI) and negative chemical ionization (GC-MS-NCI) modes are reported in this paper for the simultaneous determination of 1,3-dichloropropan-2-ol (1,3-DCP), 2,3-dichloropropan-1-ol (2,3-DCP), 3-chloropropane-1,2-diol (3-MCPD) and 2-chloropropane-1,3-diol (2-MCPD) in soy sauce and other flavoring. D5-3-MCPD (for 3-MCPD and 2-MCPD) and d5-1,3-DCP (for 1,3-DCP and 2,3-DCP) were used as the deuterium isotopic labelled internal standards. The

Xiaomin Xu; Yiping Ren; Pinggu Wu; Jianlong Han; Xianghong Shen

2006-01-01

351

Innovative method for carbon dioxide determination in human postmortem cardiac gas samples using headspace-gas chromatography-mass spectrometry and stable labeled isotope as internal standard.  

PubMed

A novel approach to measure carbon dioxide (CO2) in gaseous samples, based on a precise and accurate quantification by (13)CO2 internal standard generated in situ is presented. The main goal of this study was to provide an innovative headspace-gas chromatography-mass spectrometry (HS-GC-MS) method applicable in the routine determination of CO2. The main drawback of the GC methods discussed in the literature for CO2 measurement is the lack of a specific internal standard necessary to perform quantification. CO2 measurement is still quantified by external calibration without taking into account analytical problems which can often occur considering gaseous samples. To avoid the manipulation of a stable isotope-labeled gas, we have chosen to generate in situ an internal labeled standard gas ((13)CO2) on the basis of the stoichiometric formation of CO2 by the reaction of hydrochloric acid (HCl) with sodium hydrogen carbonate (NaH(13)CO3). This method allows a precise measurement of CO2 concentration and was validated on various human postmortem gas samples in order to study its efficiency. PMID:23746406

Varlet, V; Smith, F; de Froidmont, S; Dominguez, A; Rinaldi, A; Augsburger, M; Mangin, P; Grabherr, S

2013-05-01

352

Determination of Mustard Gas and Related Vesicants in Rubber and Paint by Gas Chromatography-Mass Spectrometry.  

National Technical Information Service (NTIS)

The determination of mustard gas (2,2'-dichlorodiethyl sulfide) and some related vesicants in rubber and paint was investigated. The vesicants were isolated by extraction with methylene chloride or by dynamic headspace analysis at elevated temperatures. T...

E. R. Wils

1992-01-01

353

Determination of methyl tert-butyl ether and tert-butyl alcohol in human urine by high-temperature purge-and-trap gas chromatography-mass spectrometry.  

PubMed

Methyl tert-butyl ether (MTBE) is the oxygenated gasoline additive most widely used in the U.S. to reduce the CO emission from motor vehicles. We developed a method using a high-temperature purge-and-trap procedure coupled with capillary gas chromatography-mass selective detection to determine MTBE and its metabolite, tert-butyl alcohol (TBA), in human urine. Several spiked-urine tests were conducted at different purging temperatures (25, 55, and 90 degrees C). The results indicated that the purging temperature affects the recovery of TBA from urine more than the recovery of MTBE. The mean recoveries of MTBE and TBA in the urine samples by the high temperature (90 degrees C) purge-and-trap gas chromatography-mass spectrometry method at different spike levels were 96.5+/-4.7% and 98.4+/-5.7%, respectively. The method was used to evaluate the urinary levels in a single subject exposed through inhalation to 1 ppm MTBE for 10 min in a controlled-environment facility. Increases in MTBE and TBA urinary excretion rates were clearly evident following the exposure to MTBE. Approximately 0.9% of the amount of MTBE inhaled was excreted unchanged as urinary MTBE, and 2.4% was excreted as urinary TBA within 10 h after exposure. The method developed is a simple, effective, sensitive, and reproducible procedure for evaluating human exposure to MTBE. PMID:9491962

Lee, C W; Weisel, C P

354

Characterization of odor-active compounds of various cherry wines by gas chromatography-mass spectrometry, gas chromatography-olfactometry and their correlation with sensory attributes.  

PubMed

To characterize the aroma of cherry wine, five samples were analyzed by quantitative descriptive sensory analysis, gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O). The aroma of cherry wines was described by 6 sensory terms as fruity, sour, woody, fermentation, cameral and floral. Fifty-one odor-active (OA) compounds were detected by GC-O and quantified by GC-MS, and 45 of them were identified. Twenty-nine OA compounds having more than 50% detection frequency were selected as specific compounds correlated to sensory attributes by partial least squares regression (PLSR). The correlation result showed ethyl 2-methyl propionate, 2,3-butanedione, ethyl butyrate, ethyl pentanoate, 3-methyl-1-butanol, ethyl hexanoate, 3-hydroxy-2-butanone, ethyl lactate, 1-hexanol, (Z)-3-hexen-1-ol, ethyl hydroxyacetate, acetic acid, furfural, 2-ethyl-1-hexanol, benzaldehyde, propanoic acid, butanoic acid, guaiacol, beta-citronellol, hexanoic acid, 2-methoxy-4-methylphenol, 2-ethyl-3-hydroxy-4H-pyran-4-one, ethyl cinnamate, 2-methoxy-4-vinylphenol were typical OA compounds, which covaried with characteristic aroma of cherry wines. PMID:21727038

Niu, Yunwei; Zhang, Xiaoming; Xiao, Zuobing; Song, Shiqing; Eric, Karangwa; Jia, Chengsheng; Yu, Haiyan; Zhu, Jiancai

2011-06-15

355

Determination of alkyl anilines and alkyl pyridines in solvent refined coal distillates and aqueous extracts by gas chromatography/mass spectrometry  

SciTech Connect

Derivatization with acetic anhydride in aqueous media coupled with capillary gas chromatography/mass spectrometry was used to distinguish alkyl anilines from alkyl pyridines. By use of this approach aniline, C-1 anilines, and C-2 anilines, as well as lesser quantities of C-2 pyridines and C-3 pyridines, were positively identified in a solvent refined coal (SRC)-II blended distallate and in an aqueous extract of the distallate. The extraction procedure and acetylation conditions employed were examined in detail and found suitable for quantitative analysis when combined with capiliary gas chromatography. The SRC-II blended distillate contained 8200-9025 ..mu..g/mL anilines and 1335 ..mu..g/mL pyridines. Distilled water equilibrated with the distillate (1:100, SRC-II:H/sub 2/O) contained 65.9-78.9 ..mu..g/mL anilines and 5.6 ..mu..g/mL pyridines.

Felice, L.J.

1982-05-01

356

Determination of alkyl anilines and alkyl pyridines in solvent refined coal distillates and aqueous extracts by gas chromatography/mass spectrometry  

SciTech Connect

Derivation with acetic anhydride in aqueous media coupled with capillary gas chromatography mass spectrometry was used to distinguish alkyl anilines from alkyl pyridines. By use of this approach aniline, C-1 anilines, and C-2 anilines, as well as lesser quantities of C-2 pyridines and C-3 pyridines, were positively identified in a solvent refined coal (SRC)-II blended distillate and in an aqueous extract of the distillate. The extraction procedure and acetylation conditions employed were examined in detail and found suitable for quantitative analysis when combined with capillary gas chromatography. The SRC-II blended distillate contained 8200-9025 ..mu..g/mL anilines and 1335 /sup +/g/mL pyridines. Distilled water equilibrated with the distillate (1:100, SRC-II:H/sub 2/O) contained 65.9-78.9 /sup +/g/mL anilines and 5.6 /sup +/g/mL pyridines. 3 figures, 1 table.

Felice, L.J.

1983-05-01

357

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

NASA Astrophysics Data System (ADS)

In order to study the relationships between the chemical structures of coals, coal macerals and their precursors (plant tissues), eight coal macerals originating from the Yorkshire coal basin (U.K.) were studied by Curie point pyrolysis-gas chromatography and Curie point pyrolysis-gas chromatography-mass spectrometry. The samples were selected on the basis of a previous study of a large set of macerals. The macerals were studied in order to relate structural moieties of the macerals, as reflected by their pyrolysis products, to structural elements of their likely precursors, plant tissues. The maceral pyrolysates mainly consist of alkylbenzenes, alkylnaphthalenes, alkylphenols and series of straight-chain alk-l-enes and alkanes over a wide molecular weight range. The relative contribution of the (hydroxy)aromatic pyrolysis products and of the straight-chain alk-l-enes and alkanes to each maceral pyrolysate was calculated, although the internal distribution patterns of the alkyl derivatives of these pyrolysis products exhibited to a certain extent dissimilarities. Differences between the relative contributions of these pyrolysis products to the pyrolysates of different macerals with the same coal rank and to those of similar macerals with different coal rank depend on differences in precursor material and the chemical modification of these precursors upon increasing coalification. Multivariate data treatment by means of factor analysis was chosen to compare the pyrolysis data - represented by these histograms - with the petrographic data and the proximate and ultimate analysis values of the macerals. In addition, similar analyses was performed on the macerals using such a low Curie temperature (358°C), that from some of the macerals "thermal extracts" were obtained, containing a series of n-alkanes and some isoprenoids such as pristane and phytane. Although these thermal extracts represent only a low percentage by weight of the maceral samples, their existence probably will affect both the chemical and physical properties of the macerals, although they are in fact no pan of the coal structure itself.

Nip, Margriet; De Leeuw, J. W.; Schenck, P. A.

1988-03-01

358

Quantification of trans-1,4-polyisoprene in Eucommia ulmoides by fourier transform infrared spectroscopy and pyrolysis-gas chromatography/mass spectrometry.  

PubMed

Commercial development of trans-1,4-polyisoprene from Eucommia ulmoides Oliver (EU-rubber) requires specific knowledge on selection of high-rubber-content lines and establishment of agronomic cultivation methods for achieving maximum EU-rubber yield. The development can be facilitated by high-throughput and highly sensitive analytical techniques for EU-rubber extraction and quantification. In this paper, we described an efficient EU-rubber extraction method, and validated that the accuracy was equivalent to that of the conventional Soxhlet extraction method. We also described a highly sensitive quantification method for EU-rubber by Fourier transform infrared spectroscopy (FT-IR) and pyrolysis-gas chromatography/mass spectrometry (PyGC/MS). We successfully applied the extraction/quantification method for study of seasonal changes in EU-rubber content and molecular weight distribution. PMID:18499051

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

2008-04-01

359

A generic approach for the determination of residues of alkylating agents in active pharmaceutical ingredients by in situ derivatization-headspace-gas chromatography-mass spectrometry.  

PubMed

A simple, reliable and fast procedure for the simultaneous determination of residues of some common alkylating agents (AAs), such as mesylates, besylates, tosylates and sulfates, employed in drug synthesis, has been developed by in situ derivatization-headspace-gas chromatography-mass spectrometry. Pentafluorothiophenol is used as a derivatizing agent in different water/dimethyl sulfoxide ratios. Compared to former analytical procedures, this approach returns improvements in analysis time, selectivity, analyte stability and method sensitivity (LOD=0.11 microgg(-1) for methyl tosylate). The method exhibits low matrix dependence, excellent accuracy, precision (R.S.D.=2.8-10% range at 1 microgg(-1)) and robustness through the use of deuterated internal standards. Knowledge of the synthetic route allows a targeted approach to the determination of specific AAs since the procedure does not distinguish between acid species. The procedure was successfully applied to different pharmaceutical matrixes, and is particularly suitable for routine analysis with high sample throughput. PMID:17719195

Alzaga, Roberto; Ryan, Robert W; Taylor-Worth, Karen; Lipczynski, Andrew M; Szucs, Roman; Sandra, Pat

2007-07-20

360

Evidence of adipocere in a burial pit from the foot and mouth epidemic of 1967 using gas chromatography-mass spectrometry.  

PubMed

Gas-chromatography-mass spectrometry was used to characterise the fatty acids from soils and associated tissues excavated from a 1967 Foot and Mouth burial pit. Subcutaneous fats were mainly comprised of 55-75% palmitic acid, 17-22% stearic acid and 3-16% oleic acid as well as 5-7% myristic acid. The distribution of fatty acids confirmed that the tissues were decayed to adipocere. The loss of oleic acid to <3% in two of the decayed fats suggested advanced stages of adipocere. However, adipocere formation was limited in a third tissue sample recovered from greater depth. Inductively coupled plasma atomic emission spectrometry of the pore waters revealed a decrease in Ca concentration and concurrent increase in Na concentrations this suggested that insoluble calcium salt had formed through displacement of sodium. The use of fatty acid profiles from soils and soil interstitial pore waters provide complementary evidence of adipocere formation in foot and mouth burial pits. PMID:16182945

Vane, Christopher H; Trick, Julian K

2004-11-10

361

Monitoring pesticide residues in greenhouse tomato by combining acetonitrile-based extraction with dispersive liquid-liquid microextraction followed by gas-chromatography-mass spectrometry.  

PubMed

A multiclass and multiresidue method for pesticide analysis in tomato was validated. Extraction and pre-concentration of the pesticide residues from acetonitrile extracts was performed by using dispersive liquid-liquid microextraction (DLLME) technique, followed by gas chromatography-mass detection. DLLME was performed using carbon tetrachloride as extractive solvent and acetonitrile extract as dispersive solvent, in order to increase enrichment factor of the extraction procedure. Validation parameters indicated the suitability of the method for routine analyses of thirty pesticides in a large number of samples. In general, pesticide recoveries ranged between 70% and 110% and repeatability ranged between 1% and 20%. The proposed method was applied to the monitoring of pesticides in tomatoes grown during winter in greenhouses. Among the compounds considered in this work, cyprodinil was found in tomato at concentrations of 0.33mg/kg, other pesticides like azoxystrobin, fenhexanid, tolyfluanid, ?-cyhalothrin and trifloxystrobin were also detected, but, not quantified. PMID:22953826

Melo, Armindo; Cunha, Sara C; Mansilha, Catarina; Aguiar, Ana; Pinho, Olívia; Ferreira, Isabel M P L V O

2012-06-07

362

[Determination of volatiles released from plants by the self-made charcoal trap adsorption device coupled with gas chromatography-mass spectrometry].  

PubMed

The charcoal trap adsorption device was designed and used to adsorb the volatile organic compounds (VOCs) emitted from Ginkgo leaves and Lima beans. The adsorbed VOCs were determined using gas chromatography-mass spectrometry (GC-MS). Compared to solid phase microextraction (SPME), the self-made charcoal trap adsorption device was more advantageous to the enrichment of VOCs from Ginkgo leaves. Additionally, the quantitative analysis of the collected VOCs released from Lima beans was carried out through the addition of internal standard, and the results of the two parallel experiments showed good repeatability. Because the eluent of the charcoal trap can be stored and used in the quantitative analysis as well as parallel experiments, the self-made charcoal trap adsorption device coupled with GC-MS is suitable for laboratory studies of plant volatile organic compounds. PMID:21046794

Guo, Shuzheng; Liu, Sujing; Ma, Xuanxuan; Yang, Cuiyun; Zhou, Shiwei; Xia, Chuanhai

2010-07-01

363

Determination of endocrine-disrupting compounds in water samples by on-line solid-phase extraction-programmed-temperature vaporisation-gas chromatography-mass spectrometry.  

PubMed

We developed an automated on-line solid-phase extraction (SPE)-gas chromatography-mass spectrometry method to determine a group of endocrine disruptors in water samples. The interface device used for connecting SPE with GC was a programmed-temperature vaporiser (PTV) whose liner was packed with Tenax. We optimized the parameters that affected both SPE and PTV working in solvent vent mode. The performance of the method was tested with several environmental water samples. The limits of detection of the method were between 0.001 and 0.036 microg l(-1) under full-scan acquisition mode. We determined phthalates and adipate in all real samples at concentrations between 0.11 and 8.10 microg l(-1). Atrazine and p,p'-DDE were also found in an irrigation stream water sample at 0.16 and 0.04 microg l(-1), respectively. PMID:12862370

Brossa, L; Marcé, R M; Borrull, F; Pocurull, E

2003-05-23

364

Confirmation by gas chromatography/mass spectrometry of two unusual trans-3-monoethylenic fatty acids from the Nova Scotian seaweeds Palmaria palmata and Chondrus crispus.  

PubMed

The structures of two unusual fatty acids, the known trans-3-hexadecenoic acid and a novel trans-3-tetradecenoic acid, both isolated from the Nova Scotian seaweeds Palmaria palmata and Chondrus crispus, were positively identified. After the extraction of the total fatty acids by saponification, followed by methylation, the monoenoic trans fractions were isolated by thin-layer chromatography on silica gel impregnated with silver nitrate. The monoenoic trans fractions were derivatized with 2-amino-2-methyl-propanol prior to analysis by gas chromatography/mass spectrometry. The mass spectra showed prominent [M + 1]+ ions but lacked the 12 amu interval useful for identifying the double bond position. Hence, alternative diagnostic peaks were used to confirm the position of the double bond in these two fatty acids. As the trans-3-hexadecenoic acid is found in the photosynthetic tissue of all plants, it may also be present in ruminant fats and, presumably, in human adipose tissue. PMID:8090067

Lamberto, M; Ackman, R G

1994-06-01

365

Simultaneous determination of 109 pesticides in unpolished rice by a combination of gel permeation chromatography and Florisil column purification, and gas chromatography/mass spectrometry.  

PubMed

A multi-residue method is described for the simultaneous analysis of 109 pesticides with different properties in unpolished rice. The range covers organophosphorus, organochlorine, carbamate, and synthetic pyrethroid pesticides. The pesticides were extracted from the sample using ethyl acetate. Most higher molecular weight components such as lipids in the co-extractives were removed by gel permeation chromatography (GPC) with a Bio-bead SX-3 column. A Florisil column with ethyl acetate/hexane as the eluting solvents was used for further cleanup. The pesticides were finally simultaneously determined by gas chromatography/mass spectrometry (GC/MS) in selective ion monitoring (SIM) mode. The average recoveries for most pesticides (spiked level 0.02, 0.1 and 1 microg/g) ranged from 70% to 110%, the relative standard deviation (RSD) was below 20% in every case, and the limit of detection (LOD) varied from 1 to 20 ng/g. PMID:16444680

Zhang, Wei-Guo; Chu, Xiao-Gang; Cai, Hui-Xia; An, Juan; Li, Chong-Jiu

2006-01-01

366

Application of capillary gas chromatography-mass spectrometry to chemical characterization of radiation-induced base damage of DNA: implications for assessing DNA repair processes  

SciTech Connect

The application of capillary gas chromatography-mass spectrometry (GC-MS) to the chemical characterization of radiation-induced base products of calf thymus DNA is presented. Samples of calf thymus DNA irradiated in N/sub 2/O-saturated aqueous solution were hydrolyzed with HCOOH, trimethylsilylated, and subjected to GC-MS analysis using a fused-silica capillary column. Hydrolysis conditions suitable for the simultaneous analysis of the radiation-induced products of all four DNA bases in a single run were determined. The trimethylsilyl derivatives of these products had excellent GC properties and easily interpretable mass spectra; an intense molecular ion (M+.) and a characteristic (M-CH/sub 3/)+ ion were observed. The complementary use of t-butyldimethylsilyl derivatives was also demonstrated. These derivatives provided an intense characteristic (M-57)+ ion, which appeared as either the base peak or the second most intense ion in the spectra. All mass spectra obtained are discussed.

Dizdaroglu, M.

1985-02-01

367

Comparison and optimization of several pretreatment techniques for determination of decabrominated diphenyl ether in polymer samples by gas chromatography mass spectrometry.  

PubMed

A sensitive quantification of decabrominated diphenyl ether (deca-BDE) was achieved by optimizing the injection temperature, pressure and column system with gas chromatography mass spectrometry in selected ion monitoring mode. A simple one-step cleanup method with acid silica gel column chromatography showed the optimum efficiency and minimum matrix interference. Ultrasonic-assisted extraction with toluene provided the best performance (111%, 1 h) as compared to Soxhlet extraction (110%, 5 h) and microwave-assisted extraction (63%, 15 min) taking consideration of extraction efficiency and consumed time. The proposed method could meet the requirement for determination of deca-BDE in polymers and has the potential to monitor the content of deca-BDE in electrical and electronic equipment for routine analysis. PMID:19359793

Li, Ying; Hashi, Yuki; Liu, Yan; Li, Hai-Fang; Lin, Jin-Ming

2009-04-01

368

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

369

Ultrasonication extraction and gel permeation chromatography clean-up for the determination of polycyclic aromatic hydrocarbons in edible oil by an isotope dilution gas chromatography–mass spectrometry.  

PubMed

An analytical method for the determination of US EPA priority pollutant 16 polycyclic aromatic hydrocarbons (PAHs) in edible oil was developed by an isotope dilution gas chromatography-mass spectrometry (GC-MS). Extraction was performed with ultrasonication mode using acetonitrile as solvent, and subsequent clean-up was applied using narrow gel permeation chromatographic column. Three deuterated PAHs surrogate standards were used as internal standards for quantification and analytical quality control. The limits of quantification (LOQs) were globally below 0.5 ng/g, the recoveries were in the range of 81-96%, and the relative standard deviations (RSDs) were lower than 20%. Further trueness assessment of the method was also verified through participation in international cocoa butter proficiency test (T0638) organised by the FAPAS with excellent results in 2008. The results obtained with the described method were satisfying (z ? 2). The method has been applied to determine PAH in real edible oil samples. PMID:20627308

Wang, Jian-Hua; Guo, Cui

2010-07-01

370

Using fast gas chromatography-mass spectrometry with auto-headspace solid-phase microextraction to determine ultra trace residues of organophosphorus pesticides in fruits.  

PubMed

Organophosphorus pesticides (OPs) in apple and tomato were determined by using fast gas chromatography-mass spectrometry (FGC-MS) coupled with auto-headspace solid-phase microextraction (SPME). The experimental conditions of FGC were investigated and developed. Three different fibers were studied and compared and it was found that the polydimethysiloxane (PDMS) was the best. Factors affecting the extract efficiency, such as extraction time, temperature, ion strength, agitator speed, and content of organic solvents, were investigated and optimized. The limits of detection (LOD) of OPs were achieved between 0.002 ng/g and 0.955 ng/g; the RSD was less than 20.9%, and the recoveries were from 79% to 117%. For most commercial fruit samples, ultra trace residues of OPs were found, mainly on the surface, and their concentrations were generally lower than LOD of conventional methods. PMID:21549025

Jiang, Yong; Ni, Yongnian; Zhu, Huifang; Zhu, Chengguang

2011-05-01

371

Optimisation of sorbent trapping and thermal desorption-gas chromatography-mass spectrometric conditions for sampling and analysis of hydrogen cyanide in air.  

PubMed

Among the chemicals belonging to the schedules of the Chemical Weapons Convention (CWC), sampling and analysis of highly volatile compounds such as hydrogen cyanide (HCN) require special consideration. The latter is present in numerous old chemical weapons that are stockpiled awaiting destruction in Northeastern France: thus, sampling on stockpile area and subsequent verification of HCN levels is compulsory to ensure safety of workers on these areas. The ability of several commercial sorbents to trap hydrogen cyanide at various concentration levels and in various humidity conditions, was evaluated. Furthermore, thermal desorption of the corresponding samples, followed by analysis by gas chromatography-mass spectrometry was also optimised. Carbosieve S-III, a molecular sieve possessing a very high specific area, proved the most efficient sorbent for HCN sampling in all conditions tested. Conversely, the presented results show that Tenax, albeit generally considered as the reference sorbent for air monitoring and analysis of CWC-related chemicals, is not suitable for HCN trapping. PMID:15912249

Juillet, Yannick; Le Moullec, Sophie; Bégos, Arlette; Bellier, Bruno

2005-04-18

372

Fungal infections of fresh-cut fruit can be detected by the gas chromatography-mass spectrometric identification of microbial volatile organic compounds.  

PubMed

There is a large and rapidly growing market for fresh-cut fruit. Microbial volatile organic compounds indicate the presence of fungal or bacterial contamination in fruit. In order to determine whether microbial volatile organic compounds can be used to detect contamination before fruit becomes unmarketable, pieces of cantaloupe, apple, pineapple, and orange were inoculated with a variety of fungal species, incubated at 25 degrees C, then sealed in glass vials. The volatiles were extracted by headspace solid-phase microextraction and analyzed by gas chromatography-mass spectrometry. Forty-five compounds were identified that might serve as unique identifiers of fungal contamination. Fungal contamination can be detected as early as 24 h after inoculation. PMID:15954710

Lloyd, Steven W; Grimm, Casey C; Klich, Maren A; Beltz, Shannon B

2005-06-01

373

Detection of VX contamination in soil through solid-phase microextraction sampling and gas chromatography/mass spectrometry of the VX degradation product bis(diisopropylaminoethyl)disulfide.  

PubMed

A solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) sampling and analysis method was developed for bis(diisopropylaminoethyl)disulfide (a degradation product of the nerve agent VX) in soil. A 30-min sampling time with a polydimethylsiloxane-coated fiber and high temperature alkaline hydrolysis allowed detection with 1.0 microg of VX spiked per g of agricultural soil. The method was successfully used in the field with portable GC-MS instrumentation. This method is relatively rapid (less than 1 h), avoids the use of complex preparation steps, and enhances analyst safety through limited use of solvents and decontamination of the soil before sampling. PMID:12735457

Hook, Gary L; Kimm, Gregory; Koch, David; Savage, Paul B; Ding, Bangwei; Smith, Philip A

2003-04-11

374

Quantitation of cocaine, benzoylecgonine, ecgonine methyl ester, and cocaethylene in urine and blood using gas chromatography-mass spectrometry (GC-MS).  

PubMed

Cocaine, a stimulant, is a commonly abused drug. Cocaine and its metabolites are measured in various biological specimens for clinical and forensic purposes. Urine or plasma or serum is spiked with deuterated internal standards cocaine-d3, benzoylecgonine-d3, ecgonine methyl ester-d3, and cocaethylene-d3 and buffered with phosphate buffer. The drugs in the sample are extracted by cation-exchange solid phase extraction. The drugs from the solid phase cartridge are eluted and the eluent is dried under the stream of nitrogen. The residue is incubated with pentafluoropropionic acid anhydride and pentafluoropropanol to form pentafluoropropionyl derivatives of ecgonine methyl ester and benzoylecgonine. Cocaine and cocaethylene are refractory to derivatization. The extract is dried, reconstituted in ethyl acetate, and injected into gas chromatography mass-spectrometry analyzer. Quantitation of the drugs in the samples is made, using selected ion monitoring, from a 3-point calibration curve. PMID:20077067

Fleming, Steven W; Dasgupta, Amitava; Garg, Uttam

2010-01-01

375

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

EPA Science Inventory

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

376

Performances under representative pressure and temperature conditions of the gas chromatography-mass spectrometry space experiment to investigate Titan's atmospheric composition.  

PubMed

In the frame of the calibration of the aerosol collector and pyrolyser, and gas chromatography-mass spectrometry experiments of the Huygens probe arrived at Titan, systematic experimental studies were led to estimate the influence of the operating conditions on the analyses that should have been achieved in the Titan's atmosphere. The primary objective of this study was to estimate the influence of operating conditions variations induced by (i) instrumental modifications made shortly before the probe launch which can have changed the operating pressures; (ii) the change of the probe environmental conditions (pressure, temperature) during its descent in the atmosphere; (iii) a possible deviation of pressure and temperature regulations from their nominal values because of the long journey of the instrument in space, or of other external events. The secondary objective of this work was to create an analytical database that can be used as a reference to treat the chromatograms obtained in situ, and help to identify chromatographically the analyzed species, complementary to mass spectrometry. Beyond the application to a specific instrument, this work was also useful to experimentally estimate the fundamental evolution of the separation as a function of the changes of operating conditions with time. The obtained results show (i) the significant influence of inlet and outlet pressure variation on the time of analysis, but not on the separation power. It thus enables to significantly shorten the analysis duration, and thus to analyze more compounds within the fixed time of analysis of the instrument; (ii) the significant influence of temperature on the retention. In this frame, the enthalpies of exchange between the gas phase and the stationary phase of the species were determined to be used to retrieve the analyzed species in case of deviation of the operating temperature; (iii) that the possible aging of the columns does not have influence on the columns efficiency and separation power; (iv) the analytical capabilities of the gas chromatography-mass spectrometry experiment within operating conditions representative of those encountered in situ. Finally, in spite of possible operating condition changes, it is shown that results coming from the gas chromatograph-mass spectrometer experiment, which are currently under analysis, could bring important information on the Titan's atmosphere and its history. PMID:16919657

Szopa, C; Freguglia, G; Sternberg, R; Nguyen, M J; Coll, P; Raulin, F; Pietrogrande, C; Niemann, H

2006-08-21

377

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

Microsoft Academic Search

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

Maur??cio Yonamine; Ovandir Alves Silva

2002-01-01

378

Quantiative determination of sulfonated aliphatic and aromatic surfactants in sewage sludge by ion-pair/supercritical fluid extraction and derivatization gas chromatography/mass spectrometry  

SciTech Connect

Secondary alkanesulfonate (SAS) and linear alkylbenzene-sulfonate (LAS) surfactants were quantitatively (> 90%) extracted from sewage sludges as their tetrabutylammonium ion pairs using 400 atm of supercritical CO[sub 2] for 5 min of static extraction followed by 10 min of dynamic extraction at 80[degrees]C. Ion pairs of SAS and LAS quantitatively formed butyl esters in the injection port of the gas chromatograph and were determined by gas chromatography/mass spectrometry without class fractionation of the sewage sludge extracts. Concentrations of SAS and LAS in sludges from five different sewage treatment plants ranged from 0.27 to 0.80 g/kg of dry sewage sludge and from 3.83 to 7.51 g/kg, respectively. Good reproducibility was achieved with RSDs of typically 5% for replicate extractions and analyses. Homologue and isomer distributions of SAS in sewage sludge indicated an enrichment of the more hydrophobic components in sewage sludge during sewage treatment. 25 refs., 5 figs., 5 tabs.

Field, J.A.; Field, T.M.; Giger, W. (Swiss Federal Inst. for Water Resources and Water Pollution Control, Duebendorf (Switzerland)); Miller, D.J.; Hawthorne, S.B. (Univ. of North Dakota, Grand Forks (United States))

1992-12-15

379

Comparison of volatile constituents extracted from model grape juice and model wine by stir bar sorptive extraction-gas chromatography-mass spectrometry.  

PubMed

A stir bar sorptive extraction (SBSE) method coupled with gas chromatography-mass spectrometry was optimised for the analysis of volatile components of a model wine, based on a previously optimised method used for analysis of the same components in model grape juice. The presence of ethanol in the model wine sample matrix resulted in decreased sensitivity of the method toward most of the volatile constituents. Mean percent relative recoveries and reproducibilities (%CV) were 22.8% and 7.1%, respectively, compared with 28.4% and 8.5% for model grape juice. The mean limit of detection (LoD) ratio (juice:wine) was 0.25. Similar sensitivities for the two sample matrices using this method were achieved by changing the split ratio from 20:1 (grape juice) to 5:1 (wine), giving a mean limit of detection ratio (juice:wine) of 1.0, thus allowing direct comparison of chromatograms of volatile components in the two matrices. This enabled direct comparisons of grape juices and the wines derived from them by alcoholic yeast fermentation. The influence of ethanol concentration in the range 9-15% on method sensitivity is discussed, using an overlay of the total ion chromatograms. The use of a gas saver device for the 5:1 split ratio analysis of desorbed model wine aroma compounds is discussed in terms of preventing extraneous reaction of sorbent and stationary phases with air during analysis. PMID:21215408

Caven-Quantrill, Darren J; Buglass, Alan J

2010-12-23

380

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.

2012-01-01

381

Detection of human butyrylcholinesterase-nerve gas adducts by liquid chromatography–mass spectrometric analysis after in gel chymotryptic digestion  

Microsoft Academic Search

To verify the exposure to nerve gas, a method for detecting human butyrylcholinesterase (BuChE)-nerve gas adduct was developed using LC–electrospray mass spectrometry (ESI-MS). Purified human serum BuChE was incubated with sarin, soman or VX, and the adduct was purified by sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) and digested in gel by treatment with chymotrypsin. The resulting peptide mixture was subjected

Kouichiro Tsuge; Yasuo Seto

2006-01-01

382

Airborne measurements of sulfur dioxide, dimethyl sulfide, carbon disulfide, and carbonyl sulfide by isotope dilution gas chromatography\\/mass spectrometry  

Microsoft Academic Search

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

Alan R. Bandy; Donald C. Thornton; Arthur R. Driedger

1993-01-01

383

Liquid chromatographic cleanup prior to determination of polychlorinated biphenyls in oil by gas chromatography/mass spectrometry  

SciTech Connect

A High Performance Liquid Chromatography (HPLC) procedure is presented which eliminates mass spectral interferences from transformer and waste oils. The resulting HPLC fraction is clean enough to be analyzed for polychlorinated biphenyls (OCBs) by gas chromatography/chemical ionization mass spectrometry (GC/CIMS) down to the 100ppb level. 8 references, 3 figures, 1 table.

Nero, V.P.; Hudson, R.D.

1984-01-01

384

Determination of major volatile compounds during the production of fruit vinegars by static headspace gas chromatography–mass spectrometry method  

Microsoft Academic Search

A static headspace gas chromatography coupled to mass spectrometry (SHS–GC–MS) method was validated to determine several major volatile components during the production process of fruit vinegars. The method is simple, fast, linear in the working range, suitably sensitive, repeatable and reproducible, and has a good degree of accuracy for most of the compounds studied. Different conditions were tested in the

C. Ubeda; R. M. Callejón; C. Hidalgo; M. J. Torija; A. Mas; A. M. Troncoso; M. L. Morales

2011-01-01

385

In situ silylation for the multicomponent analysis of canola oil by-products by gas chromatography–mass spectrometry  

Microsoft Academic Search

In this study, a simple method for the determination of free fatty acids, phytosterols, tocopherols, mono and diglycerides present in canola oil deodorizer distillate (DD) and soapstock samples was developed. Analytes were derivatized “in situ” using a mixture of hexamethyldisilazane (HMDS), pyridine and trifluoroacetic acid; separated by gas chromatography (GC) with mass spectrometry (MS) for final detection. Two drying procedures

Armando A. Durant; Marie-Josée Dumont; Suresh S. Narine

2006-01-01

386

Quick identification of polycarboxylates in laundry detergents by in situ pyrolysis-methylation gas chromatography\\/mass spectrometry  

Microsoft Academic Search

This report summarizes method development for the identification of polycarboxylates using in situ pyrolysis-methylation gas chromatography (GC) with mass detection. Ground detergent products are dissolved in water together with a methylation reagent, tetramethylammonium hydroxide. The solution is centrifuged and an aliquot of supernatant is pyrolyzed after water is evaporated. Key fragments separated via GC are detected with a mass selective

Akihiko Kawauchi; Toshihiko Uchiyama

1998-01-01

387

Accuracy profile validation of a new analytical method for butane measurement using headspace-gas chromatography-mass spectrometry.  

PubMed

The aim of our study was to provide an innovative HS-GC/MS method applicable to the routine determination of butane concentration in forensic toxicology laboratories. The main drawback of the GC/MS methods discussed in literature concerning butane measurement was the absence of a specific butane internal standard necessary to perform quantification. Because no stable isotope of butane is commercially available, it is essential to develop a new approach by an in situ generation of standards. To avoid the manipulation of a stable isotope-labelled gas, we have chosen to generate in situ an internal labelled standard gas (C(4)H(9)D) following the basis of the stoichiometric formation of butane by the reaction of deuterated water (D(2)O) with Grignard reagent butylmagnesium chloride (C(4)H(9)MgCl). This method allows a precise measurement of butane concentration and therefore, a full validation by accuracy profile was presented. PMID:23314353

Varlet, V; Smith, F; Augsburger, M

2012-12-12

388

Determination of 4,4?-methylenediphenyldianiline (MDA) and identification of isomers in technical-grade MDA in hydrolysed plasma and urine from workers exposed to methylene diphenyldiisocyanate by gas chromatography-mass spectrometry  

Microsoft Academic Search

Gas chromatography-mass spectrometry using chemical ionization with ammonia as reagent gas monitoring both positive and negative ions was applied. Negative-ion monitoring using ammonia and the pentafluoropropionic anhydride (PFPA) derivatives were chosen owing to low detection limits and good separation for the isomers studied. Technical-grade methylenediphenyldiioscyanate (MDI) was analysed and three isomers, 4,4??, 2.4?? and 2,2?methylenediphenyldianiline (MDA), were determined in addition

Gunnar Skarping; Marianne Dalene

1995-01-01

389

Rapid method for the simultaneous measurement of nicotine and cotinine in urine and serum by gas chromatography-mass spectrometry.  

PubMed

A simple, sensitive, and rapid gas chromatographic-mass spectrometric method is described for the simultaneous detection and quantitation of nicotine and its metabolite, cotinine, in urine and serum. The analytes and their respective deuterated internal standards were extracted by liquid-liquid extraction coupled to centrifugation and evaporation. The detection limit of the assay was 0.16 ng/ml for both nicotine and cotinine. The limit of quantitation for each analyte was 1.25 ng/ml. PMID:9653950

James, H; Tizabi, Y; Taylor, R

1998-04-24

390

Isotope dilution determination of polycyclic aromatic hydrocarbons in olive pomace oil by gas chromatography–mass spectrometry  

Microsoft Academic Search

A gas chromatographic (GC) method with mass spectrometry detection (MS) for the determination of eight polycyclic aromatic hydrocarbons (PAHs) in olive pomace oil has been developed. The oil was diluted with n-pentane and extracted by liquid–liquid partition with dimethyl sulphoxide (DMSO). After water addition and back-extraction with cyclohexane, a thin-layer chromatography on silica gel was performed as a further purification

Gianfranco Diletti; Giampiero Scortichini; Rossana Scarpone; Giuseppe Gatti; Luigi Torreti; Giacomo Migliorati

2005-01-01

391

Full-range analysis of ambient volatile organic compounds by a new trapping method and gas chromatography\\/mass spectrometry  

Microsoft Academic Search

This study investigated the feasibility of analyzing a full range of ambient volatile organic compounds (VOCs) from C3 to C12 using gas chromatograph mass spectrometry (GC\\/MS) coupled with thermal desorption. Two columns were used: a PLOT column separated compounds lighter than C6 and a DB-1 column separated C6–C12 compounds. An innovative heart-cut technique based on the Deans switch was configured

Yuan-Chang Su; Wen-Tzu Liu; Wei-Cheng Liao; Sen-Wei Chiang; Jia-Lin Wang

2011-01-01

392

Multiresidue determination of pesticides in juice by solid-phase extraction and gas chromatography–mass spectrometry  

Microsoft Academic Search

A multiresidue method based on solid-phase extraction was developed for the simultaneous determination of 50 pesticides in commercial juices. The extraction procedure was carried out in C18 columns preconditioned with acetonitrile and water. The subsequent elution of pesticides was performed with a mixture of hexane-ethyl acetate (1:1, v\\/v) prior to the determination by gas chromatography with electron impact mass spectrometric

Beatriz Albero; Consuelo Sánchez-Brunete; José L. Tadeo

2005-01-01

393

Screening for sarin in air and water by solid-phase microextraction-gas chromatography\\/mass spectrometry  

Microsoft Academic Search

A method of screening air and water samples for the chemical-warfare agent Sarin is developed using solid-phase microextraction (SPME)-gas chromatography (GC)-mass spectrometry (MS). The SPME field kit sampler is ideal for collecting air and water samples in the field and transporting samples safely to the laboratory. The sampler also allows the sample to be introduced into the GC-MS system without

J. F. Schneider; A. S. Boparai; L. L. Reed

2001-01-01

394

Determination of endogenous and synthetic glucocorticoids in human urine by gas chromatography–mass spectrometry following microwave-assisted derivatization  

Microsoft Academic Search

A complete screening and confirmation analytical method for the direct determination of six endogenous (cortisol, cortisone, deoxycorticosterone, tetrahydrocortisol, tetrahydrocortisone, tetrahydro-S) and 17 synthetic (amcinonide, betamethasone, desoximethasone, dexamethasone, fludrocortisone, flumethasone, flunisolide, flucinolone acetonide, flucinonide, fluprednisolone, flurandrenolide, fluorometholone, 6-methylprednisolone, prednisolone, prednisone, triamcinolone, triamcinolone acetonide) glucocorticoids in human urine by gas chromatography with mass spectrometric detection (GC–MS) is presented.The analytical technique comprises a

Luca Amendola; Flaminia Garribba; Francesco Botrè

2003-01-01

395

Determination of aliphatic amines by gas chromatography–mass spectrometry after in-syringe derivatization with pentafluorobenzoyl chloride  

Microsoft Academic Search

A simple and highly sensitive gas chromatographic method has been developed for the determination of low molecular weight short-chain aliphatic amines (SCAAs) after their simultaneous extraction and in-syringe derivatization with pentafluorobenzoyl chloride (PFBOC). Derivatization of the low molecular weight aliphatic amines in bicarbonate buffer of pH 10.5 with PFBOC was followed by immersed solvent microextraction. Derivatization conditions, including reagent concentration,

Deepesh Kumar Singh; Sunil Kumar Sanghi; Sorna Gowri; Navin Chandra; Shail Bala Sanghi

2011-01-01

396

Quick identification of polymeric dye transfer inhibitors in laundry detergents by pyrolysis-gas chromatography\\/mass spectrometry  

Microsoft Academic Search

This report summarizes method development for the simultaneous identification of dye transfer inhibitors (DTIs) using pyrolysis-gas chromatography with mass detection (Py-GC\\/MS). Ground detergent products are directly pyrolyzed and pyrolysis fragments introduced into a GC column. Key fragments separated via GC are detected by selected ion monitoring (SIM) to achieve the high sensitivity and selectivity necessary to measure markers of DTIs

Toshihiko Uchiyama; Akihiko Kawauchi; Dean L DuVal

1998-01-01

397

The measurement of dimethylamine, trimethylamine, and trimethylamine N-oxide using capillary gas chromatography-mass spectrometry.  

PubMed

We have developed a method for measuring dimethylamine (DMA), trimethylamine (TMA), and trimethylamine N-oxide (TMAO) in biological samples using gas chromatography with mass spectrometric detection. DMA, TMA, and TMAO were extracted from biological samples into acid after internal standards (labeled with stable isotopes) were added. p-Toluenesulfonyl chloride was used to form the tosylamide derivative of DMA. 2,2,2-Trichloroethyl chloroformate was used to form the carbamate derivative of TMA. TMAO was reduced with titanium(III) chloride to form TMA, which was then analyzed. The derivatives were chromatographed using capillary gas chromatography and were detected and quantitated using electron ionization mass spectrometry (GC/MS). Derivative yield, reproducibility, linearity, and sensitivity of the assay are described. The amounts of DMA, TMA, and TMAO in blood, urine, liver, and kidney from rats and humans, as well as in muscle from fishes, were determined. We also report the use of this method in a pilot study characterizing dimethylamine appearance and disappearance from blood in five human subjects after ingesting [13C]dimethylamine (0.5 mumol/kg body wt). The method we describe was much more reproducible than existing gas chromatographic methods and it had equivalent sensitivity (detected 1 pmol). The derivatized amines were much more stable and less likely to be lost as gases when samples were stored. Because we used GC/MS, it was possible to use stable isotopic labels in studies of methylamine metabolism in humans. PMID:2382825

daCosta, K A; Vrbanac, J J; Zeisel, S H

1990-06-01

398

Determination of aromatic amines in hair dye and henna samples by ion-pair extraction and gas chromatography-mass spectrometry.  

PubMed

A gas chromatography-mass spectrometry (GC-MS) method has been proposed for the determination of carcinogenic and toxic aromatic amines in hair dye, henna and dyed hair samples. The method includes ion-pair extraction of aromatic amines from aqueous samples with bis-2-ethylhexylphosphate (BEHPA) released after solving the samples in acidic solution followed by sonication, derivatisation of compounds with isobutyl chloroformate (IBCF) and their GC-MS analysis in both electron impact (EI) and positive and negative ion chemical ionisation (PNICI) mode as their isobutyloxycarbonyl (isoBOC) derivatives. The obtained recoveries of aromatic amines ranged from 92.2 to 98.4% and the precision of this method, as indicated by the relative standard deviations (RSDs) was within the range of 0.7-4.2%. The detection limits obtained from calculations by using GC-MS results based on signal-to-noise ratio (S/N)=3 were within the range from 0.02 to 0.20 ng/g. In the present study, the commercially available 54 permanent hair dye, 35 modified or natural henna and 15 dyed hair samples were analysed for the aromatic amines by the proposed method and the method was shown to be suitable to determine the aromatic amine ingredients and metabolites of these commercial products. PMID:18280687

Akyüz, Mehmet; Ata, Sevket

2007-12-15

399

Bile acid profiles of human serum and skin interstitial fluid and their relationship to pruritus studied by gas chromatography-mass spectrometry.  

PubMed

1. Pruritus was assessed in 19 patients by measurement of nocturnal limb movement. 2. Serum (nine pruritic, ten non-pruritic) and interstitial fluid (five pruritic, three non-pruritic) bile acids were fractionated according to their mode of conjugation by using DEAP-Sephadex LH-20 and measured by gas chromatography-mass spectrometry. 3. No correlation was found between serum or interstitial fluid total bile acid or individual bile acid concentrations and pruritus. Bile acid profiles in the two groups of patients were similar and there was no correlation between pruritus and the conjugation pattern. 4. Te bile acid profile of interstitial fluid reflected that of serum and a linear relationship was found between serum and interstitial fluid bile acid concentrations (r ;.95, P less than 0.001). 5. The proportion of bile acid sulphate in interstitial fluid was significantly smaller than that in serum (P less than 0.025), where sulphates accounted for up to 46% of the total bile acids. 6. In three patients, a decrease in serum bile acid concentrations achieved by percutaneous transhepatic biliary drainage had little or no effect on pruritus. 7. These findings suggest that bile acids do not have a causative role in the pruritus of cholestatic liver disease. PMID:7083767

Bartholomew, T C; Summerfield, J A; Billing, B H; Lawson, A M; Setchell, K D

1982-07-01

400

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

PubMed

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

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

2010-04-01

401

Development of gas chromatography-mass spectrometry with microwave distillation and simultaneous solid-phase microextraction for rapid determination of volatile constituents in ginger.  

PubMed

In this study, gas chromatography-mass spectrometry (GC-MS) following microwave distillation and solid-phase microextraction (MD-SPME) was developed for the analysis of essential oil compounds in fresh ginger. In the proposed method, the isolation, extraction and concentration of volatile components in ginger were carried out in one single step, using the MD-SPME technique, and the analytes on the SPME fiber were analyzed by GC-MS. Some parameters, including SPME fiber coating, microwave power and irradiation time, were optimized. The optimal experiment parameters obtained were: 65 microm PDMS/DVB SPME fiber, a microwave power of 400 W and an irradiation time of 2 min. To demonstrate its feasibility, MD-SPME was compared with conventional SPME for the extraction of essential oil compounds in fresh ginger. Using MD-SPME followed by GC-MS, 54 compounds were separated and identified in ginger, which mainly included geranial (5.25%), zingiberene (15.48%), beta-sesquiphellandrene (5.54%) and beta-phellandrene (22.84%), whereas only 39 compounds were separated and identified by conventional SPME followed by GC-MS. The relative standard deviation (R.S.D.) values of less than 10% show that the proposed method has good repeatability. The result show that MD-SPME, followed by GC-MS, is a simple, rapid, solvent-free method for the determination of volatile compounds in ginger. PMID:16890394

Yu, Yingjia; Huang, Taomin; Yang, Bei; Liu, Xiang; Duan, Gengli

2006-08-04

402

Stir bar sorptive extraction with gas chromatography-mass spectrometry for the determination of resveratrol, piceatannol and oxyresveratrol isomers in wines.  

PubMed

A simple and highly sensitive procedure based on stir bar sorptive extraction coupled to gas chromatography-mass spectrometry by means of a thermal desorption unit (SBSE-TD-GC-MS) has been optimized for the determination of cis/trans isomers of resveratrol, piceatannol and oxyresveratrol in wine samples. Quantification of the cis-isomers was carried out by generating the standards from the corresponding trans-species once they had been preconcentrated on the SBSE extracting phase. The optimization of the acetylation derivatization, SBSE extraction and thermal desorption steps was investigated using Plackett-Burman designs, taking into account the high number of variables to be considered. The use of bisphenol F as internal standard allowed quantification of the samples against aqueous standards. Repeatability, expressed as relative standard deviation of 10 successive analyses was between 5% and 9%, confirming the high precision attained under the optimized conditions. Satisfactory recovery values of between 79% and 109% were obtained for spiked samples in the 0.2-1.0?gL(-1) concentration range, depending on the compound. The main compound determined in the analyzed samples was trans-resveratrol, with concentrations in the range of 3-230?gL(-1), depending on the type of wine. PMID:24075014

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

2013-09-18

403

Evaluation of solid-phase micro-extraction coupled to gas chromatography-mass spectrometry for the headspace analysis of volatile compounds in cocoa products.  

PubMed

The aroma profile of cocoa products was investigated by headspace solid-phase micro-extraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS). SPME fibers coated with 100 microm polydimethylsiloxane coating (PDMS), 65 microm polydimethylsiloxane/divinylbenzene coating (PDMS-DVB), 75 microm carboxen/polydimethylsiloxane coating (CAR-PDMS) and 50/30 microm divinylbenzene/carboxen on polydimethylsiloxane on a StableFlex fiber (DVB/CAR-PDMS) were evaluated. Several extraction times and temperature conditions were also tested to achieve optimum recovery. Suspensions of the samples in distilled water or in brine (25% NaCl in distilled water) were investigated to examine their effect on the composition of the headspace. The SPME fiber coated with 50/30 microm DVB/CAR-PDMS afforded the highest extraction efficiency, particularly when the samples were extracted at 60 degrees C for 15 min under dry conditions with toluene as an internal standard. Forty-five compounds were extracted and tentatively identified, most of which have previously been reported as odor-active compounds. The method developed allows sensitive and representative analysis of cocoa products with high reproducibility. Further research is ongoing to study chocolate making processes using this method for the quantitative analysis of volatile compounds contributing to the flavor/odor profile. PMID:18371766

Ducki, Sylvie; Miralles-Garcia, Javier; Zumbé, Albert; Tornero, Antonio; Storey, David M

2007-09-02

404

Kinetics of labelling of organic and amino acids in potato tubers by gas chromatography-mass spectrometry following incubation in (13)C labelled isotopes.  

PubMed

Metabolic pathways of primary metabolism of discs isolated from potato tubers were evaluated by the use of a gas chromatography-mass spectrometry (GC-MS) method generated specifically for this purpose. After testing several possible methods including chemical ionization, it was decided for reasons of sensitivity, reproducibility and speed to use electron impact ionization-based GC-MS analysis. The specific labelling and label accumulation of over 30 metabolites including a broad number of sugars, organic and amino acids was analysed following the incubation of tuber discs in [U-(13)C]glucose. The reproducibility of this method was similar to that found for other GC-MS-based analyses and comparison of flux estimates from this method with those obtained from parallel, yet less comprehensive, radiolabel experiments revealed close agreement. Therefore, the novel method allows quantitatively evaluation of a broad range of metabolic pathways without the need for laborious (and potentially inaccurate), chemical fractionation procedures commonly used in the estimation of fluxes following incubation in radiolabelled substrates. As a first experiment the GC-MS method has been applied to compare the metabolism of wild type and well-characterized transgenic potato tubers exhibiting an enhanced sucrose mobilization. The fact that this method is able to rapidly yield further comprehensive information into primary metabolism illustrates its power as a further phenotyping tool for the analysis of plant metabolism. PMID:15272882

Roessner-Tunali, Ute; Liu, JunLi; Leisse, Andrea; Balbo, Ilse; Perez-Melis, Alicia; Willmitzer, Lothar; Fernie, Alisdair R

2004-08-01

405

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

2012-09-04

406

Simultaneous determination of trace sterols in complicated biological samples by gas chromatography-mass spectrometry coupled with extraction using ?-sitosterol magnetic molecularly imprinted polymer beads.  

PubMed

In this paper, an efficient and sensitive analytical method for the simultaneous determination of three trace sterols including ergosterol, stigmasterol and ?-sitosterol in complicated biological samples was developed by gas chromatography-mass spectrometry (GC-MS) coupled with extraction using novel ?-sitosterol magnetic molecularly imprinted polymer (mag-MIP) beads. Physical tests suggested that ?-sitosterol mag-MIP beads prepared by a rapid microwave synthesis method possessed the porous morphology, narrow size distribution, stable chemical and thermal property. Due to the greatly enlarging surface area and the strong recognition to the target molecules, ?-sitosterol mag-MIP beads have a higher enrichment factor for ?-sitosterol (?20-fold) and the higher selectivity for ?-sitosterol and its analogs than that of ?-sitosterol magnetic nonimprinted polymer (mag-NIP) beads. Under the optimum analytical conditions, all the target compounds achieved good chromatographic separation and sensitive detection without matrix interference. It was interesting that three target sterols were actually found in mushroom samples, and stigmasterol and ?-sitosterol were actually found in serum and watermelon samples. The recoveries of spiked sample tests were in range of 71.6-88.2% with RSDs of 2.4-10.0% (n=3). This method is reliable and applicable for the simultaneous determination of trace sterols in real biological samples based on the ?-sitosterol mag-MIP bead extraction. PMID:21632061

Zhang, Zhuomin; Tan, Wei; Hu, Yuling; Li, Gongke

2011-05-14

407

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

PubMed Central

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

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

2010-01-01

408

Determination of cocaine, its metabolites, pyrolysis products, and ethanol adducts in postmortem fluids and tissues using Zymark automated solid-phase extraction and gas chromatography-mass spectrometry.  

PubMed

Demonstrating the presence or absence of cocaine (COC) and COC-related molecules in postmortem fluids and/or tissues can have serious legal consequences and may help determine the cause of impairment and/or death. We have developed a simple method for the simultaneous determination of COC and the COC metabolites benzoylecgonine (BE), norbenzoylecgonine (NBE), ecgonine methyl ester (EME), ecgonine (E), and norcocaine (NCOC), as well as anhydroecgonine methyl ester (AEME) (a unique byproduct of COC smoking), cocaethylene (a molecule formed by the concurrent use of COC and ethanol) and their related metabolites, anhydroecgonine (AE), norcocaethylene (NCE), and ecgonine ethyl ester (EEE). This method incorporates a Zymark RapidTrace automated solid-phase extraction (SPE) system, gas chromatography/mass spectrometry (GC/MS) and 2,2,3,3,3-pentafluoro-1-propanol (PFP)/pentafluoropropionic anhydride (PFPA) derivatives. The lower limits of detection ranged from 0.78 to 12.5 ng/mL and the linear dynamic range for most analytes was 0.78-3200 ng/mL. The extraction efficiencies were from 26 to 84% with the exception of anhydroecgonine and ecgonine, which were from 1 to 4%. We applied this method to five aviation fatalities. This method has proven to be simple, robust and accurate for the simultaneous determination of COC and 11 COC metabolites in postmortem fluids and tissues. PMID:15171923

Lewis, Russell J; Johnson, R D; Angier, M K; Ritter, R M

2004-07-01

409

Agarose film liquid phase microextraction combined with gas chromatography-mass spectrometry for the determination of polycyclic aromatic hydrocarbons in water.  

PubMed

Agarose film liquid phase microextraction (AF-LPME) procedure for the extraction and preconcentration of polycyclic aromatic hydrocarbons (PAHs) in water has been investigated. Agarose film was used for the first time as an interface between donor and acceptor phases in liquid phase microextraction which allowed for selective extraction of the analytes prior to gas chromatography-mass spectrometry. Using 1-octanol as acceptor phase, high enrichment factors in the range of 57-106 for the targeted analytes (fluorene, phenanthrene, fluoranthene and pyrene) were achieved. Under the optimum extraction conditions, the method showed good linearity in the range of 0.1-200 ?gL(-1), good correlation coefficients in the range of 0.9963-0.9999, acceptable reproducibility (RSD 6.1-9.2%, n=3), low limits of detection (0.01-0.04 ?gL(-1)) and satisfactory relative recoveries (92.9-104.7%). As the AF-LPME device was non-expensive, reuse or recycle of the film was not required, thus eliminating the possibility of analytes carry-over between runs. The AF-LPME technique is environment-friendly and compatible with the green chemistry concept as agarose is biodegradable polysaccharide extracted from seaweed and the procedure requires small volume of organic solvent and generates little waste. The validated method was successfully applied to the analysis of the four analytes in river water samples. PMID:23021646

Sanagi, Mohd Marsin; Loh, Saw Hong; Wan Ibrahim, Wan Aini; Hasan, Mohamed Noor

2012-09-11

410

Ancient wood of the Acqualadrone rostrum: materials history through gas chromatography/mass spectrometry and sulfur X-ray absorption spectroscopy.  

PubMed

In 2008 the rostrum from an ancient warship was recovered from the Mediterranean near Acqualadrone, Sicily. To establish its provenance and condition, samples of black and brown rostrum wood were examined using sulfur K-edge X-ray absorption spectroscopy (XAS) and gas chromatography/mass spectrometry (GC/MS). GC/MS of pyrolytic volatiles yielded only guaiacyl derivatives, indicating construction from pinewood. A derivatized extract of black wood yielded forms of abietic acid and sandaracopimaric acid consistent with pine pitch waterproofing. Numerical fits to the sulfur K-edge XAS spectra showed that about 65% of the endogenous sulfur consisted of thiols and disulfides. Elemental sulfur was about 2% and 7% in black and brown wood, respectively, while pyritic sulfur was about 12% and 6%. About 2% of the sulfur in both wood types was modeled as trimethylsulfonium, possibly reflecting biogenic (dimethylsulfonio)propionate. High-valent sulfur was exclusively represented by sulfate esters, consistent with bacterial sulfotransferase activity. Traces of chloride were detected, but no free sulfate ion. In summary, the rostrum was manufactured of pine wood and subsequently waterproofed with pine pitch. The subsequent 2300 years included battle, foundering, and marine burial followed by anoxia, bacterial colonization, sulfate reduction, and mobilization of transition metals, which produced pyrite and copious appended sulfur functionality. PMID:22545724

Frank, Patrick; Caruso, Francesco; Caponetti, Eugenio

2012-04-30

411

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

412

Rapid and effective sample clean-up based on magnetic multiwalled carbon nanotubes for the determination of pesticide residues in tea by gas chromatography-mass spectrometry.  

PubMed

In this work, amine-functionalised magnetic nanoparticles and multiwalled carbon nanotubes (MNPs/MWCNTs) composites were synthesised by a simple method and applied as an adsorbent for rapid clean-up of acetonitrile extracts of tea samples prior to analysing eight pesticide residues by gas chromatography-mass spectrometry. Several parameters affecting the sampling and treatment efficiency were investigated, including extraction solvent, sonication time, weight ratio of MWCNTs to MNPs in the composites, amount of adsorbent, clean-up time and washing solution. Under the optimised conditions, the recoveries obtained for each pesticide ranged from 72.5% to 109.1% with relative standard deviations lower than 12.6%. Limit of quantification ranged from 0.02 to 0.08mgkg(-1). The established method was successfully applied to the analysis of pesticide residues in real tea samples. The results indicated that the use of MNPs/MWCNTs composites allowed the simple and expeditious clean-up of complex tea samples for subsequent determination of pesticide residues. PMID:24128556

Deng, Xiaojuan; Guo, Qianjin; Chen, Xiaoping; Xue, Tao; Wang, Hui; Yao, Pei

2013-09-06

413

[Pplications 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

414

Development of a method for the determination of UV filters in water samples using stir bar sorptive extraction and thermal desorption-gas chromatography-mass spectrometry.  

PubMed

Stir bar sorptive extraction (SBSE) in combination with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) was applied for the determination of 9 UV filters in water samples. The stir bar coated with polydimethylsiloxane (PDMS) was added to 20 mL of water sample at pH 2 (10% MeOH) and stirred at 1000 rpm for 180 min. Then, the stir bar was subjected to TD-GC-MS. The desorption conditions (desorption temperature and desorption time) and SBSE parameters (ionic strength, pH, presence of organic solvent and time) were optimised using a full factorial design and a Box-Behnken design, respectively. The method shows good linearity (correlation coefficients >0.994) and reproducibility (RSD<16%). The extraction efficiencies were above 63% for all the compounds. Detection limits were between 0.2 and 63 ng/L. The developed method offers the ability to detect several UV filters at ultra-low concentration levels with only 20 mL of sample volume. The effectiveness of the method was tested by analysing real samples such as lake water, river water and treated wastewater. The application of the method allowed reporting the levels of UV filters in environmental water samples. PMID:18096171

Rodil, Rosario; Moeder, Monika

2007-12-04

415

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

PubMed

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

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

2007-08-01

416

Determination of eight selected organophosphorus insecticides in postmortem blood samples using solid-phase extraction and gas chromatography/mass spectrometry.  

PubMed

A simple, rapid and sensitive method is described for the determination of omethoate, dimethoate, diazinon, chlorpyrifos, parathion-ethyl, chlorfenvinphos, quinalphos and azinphos-ethyl in postmortem whole blood samples. The analytes and internal standard (ethion) were isolated from the matrix by solid-phase extraction, and were analysed by gas chromatography/mass spectrometry in the selected ion monitoring mode. The method has shown to be selective after analysis of postmortem samples of 40 different origins. Calibration curves were established between 0.05 (0.1 for omethoate) and 25?µg/mL, and the values obtained for intra- and interday precision and accuracy were within the criteria usually accepted for bioanalytical method validation. Lower limits of quantitation were 50?ng/mL for all compounds, except for omethoate (100?ng/mL); the limits of identification of the method were 25?ng/mL for all analytes, except for omethoate, for which 50?ng/mL was obtained. Absolute recovery was determined at three concentration levels, and ranged from 31 to 108%. The proposed method is simple and fast, and can be routinely applied in the determination of these compounds in postmortem whole blood samples within the scope of forensic toxicology. In addition, mass spectrometry has demonstrated to be a powerful and indispensable tool for the unequivocal identification of the analytes, since the acceptance criteria were accomplished even at very low levels, thus allowing obtaining forensically valid and sound results. PMID:20941767

Raposo, R; Barroso, M; Fonseca, S; Costa, S; Queiroz, J A; Gallardo, E; Dias, M

2010-11-15

417

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 495°C), 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

Tölgyessy, Peter; Vrana, Branislav; Krascsenits, Zoltán

2011-10-01

418

Enzymatic Digestion and Selective Quantification of Underivatised Delta-9-Tetrahydrocannabinol and Cocaine in Human Hair Using Gas Chromatography-Mass Spectrometry  

PubMed Central

Gas chromatography-mass spectrometric (GC-MS) methods for drug analysis routinely employ derivatising reagents. The aim of this paper was to develop a method for the analysis of two recreational drugs, delta-9-tetrahydrocannabinol (?9-THC) and cocaine in hair samples using GC-MS, without prior derivatisation, thus allowing the sample to be reanalysed in its original form. An enzymatic digestion technique was also developed. Ten hair samples, that were known positive for either ?9-THC and/or cocaine, were enzymatically digested, extracted, and then analysed by GC-MS. All samples measured contained ?9-THC and one sample contained cocaine. The limits of detection (LOD) and quantification (LOQ) were 0.02?ng/mg and 0.05?ng/mg, respectively, for cocaine and 0.015?ng/mg and 0.02?ng/mg, respectively, for ?9-THC. The wide detection window, ease of direct analysis by GC-MS, lower detection limits of underivatised samples, and the stability of drugs using this technique may offer an improved method of analysis.

Breidi, Salah Eddine; Barker, James; Petroczi, Andrea; Naughton, Declan P.

2012-01-01

419

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

2013-05-07

420

Simple and sensitive determination of Delta(9)-tetrahydrocannabinol, cannabidiol and cannabinol in hair by combined silylation, headspace solid phase microextraction and gas chromatography-mass spectrometry.  

PubMed

A new method for determination of Delta(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 chromatography-mass spectrometry was developed and evaluated. The limits of detection of the three compounds were 0.01-0.02 ng/mg. The method was routinely applied to more than 250 hair samples. In 77 positive samples, the concentrations ranged from LOD to 4.2 ng/mg for THC (mean 0.49 ng/mg), to 12.1 ng/mg for CBD (mean 0.37 ng/mg) and to 0.85 ng/mg for CBN (mean 0.12 ng/mg) using a sample amount of 30 mg. The frequently observed increase of the segmental drug concentrations from proximal to distal is explained by progressive accumulation in the hair shaft from sebum or side stream smoke. PMID:16971195

Nadulski, Thomas; Pragst, Fritz

2006-09-12

421

Trace analysis of ethanol, MTBE, and related oxygenate compounds in water using solid-phase microextraction and gas chromatography/mass spectrometry.  

PubMed

Solid-phase microextraction (SPME) and gas chromatography/mass spectrometry have been combined for trace-level determination of very polar compounds in water, including the widely used gasoline oxygenates ethanol and methyl tert-butyl ether (MTBE). A relatively simple extraction method using a divinylbenzene/Carboxen/poly(dimethylsiloxane) SPME fiber was optimized for the routine analysis of ethanol and MTBE in groundwater and reagent water. A sodium chloride concentration of 25% (w/w) combined with an extraction time of 25 min provided the greatest sensitivity while maintaining analytical efficiency. Replicate analyses in fortified reagent and groundwater spiked with microgram per liter concentrations of ethanol and MTBE indicate quantitative and reproducible recovery of these and related oxygenate compounds. Method detection limits were 15 microg L(-1) for ethanol, 1.8 microg L(-1) for tert-butyl alcohol, 0.038 microg L(-1) for tert-amyl methyl ether, 0.025 microg L(-1) for ethyl-tert-butyl ether, and 0.008 microg L(-1) for MTBE. PMID:11028625

Cassada, D A; Zhang, Y; Snow, D D; Spalding, R F

2000-10-01

422

Determination of ortho-phthalaldehyde in water by high performance liquid chromatography and gas chromatography-mass spectrometry after hydrazine derivatization.  

PubMed

A simple high performance liquid chromatographic (HPLC) method and a highly sensitive gas chromatography mass spectrometric (GC-MS) method have been established for the determination of ortho-phthalaldehyde (OPA) in water. These methods are based on the derivatization of OPA with hydrazine in water. The following optimum reaction conditions were established: reagent dosage, 20 mg/mL of hydrazine; pH 2; reaction for 20 min at 70 °C. The organic derivative was detected directly by HPLC or after the extraction with methylene chloride/concentration by GC-MS. The limit of detection of OPA in water was 4.0 and 0.3 ?g/L by HPLC and GC-MS, respectively. The calibration curve showed good linearity with r² = 0.9993 and r² = 0.9994 by HPLC and GC-MS, respectively, the accuracy was in a range of 95-105%, and the precision of the assay was less than 13% in water. The HPLC method was simple and reproducible enough to permit the OPA content analysis in the disinfectant products, and the GC-MS method is sensitive enough to permit reliable analysis of OPA to the ?g/L level in environmental water. PMID:22683188

Oh, Jin-Aa; Shin, Ho-Sang

2012-05-26

423

Oral administration of dehydroepiandrosterone to healthy men: alteration of the urinary androgen profile and consequences for the detection of abuse in sport by gas chromatography-mass spectrometry.  

PubMed

Dehydroepiandrosterone (DHEA) replacement therapy as compensation for high age-related decline of DHEA and DHEA sulfate production is a matter of intense investigation, since many beneficial effects have been proven, or are suggested and expected. Therefore, DHEA abuse by athletes has been considered by the International Olympic Committee, which banned the substance recently. As DHEA for oral supplementation is easily available, we decided to investigate the effect on the urinary androgen profile of administration along this route of a single substitution dose of 50 mg. Quantitative analysis by gas chromatography-mass spectrometry with selected ion monitoring demonstrated that the drug was readily absorbed with 50 to 75% recovery of dosing after 24 h, and with glucuro- and sulfoconjugates of DHEA, androsterone, and etiocholanolone as the most abundant metabolites. In agreement with reported data found in blood, conversion of exogenous DHEA to the principal biologically active androgen, testosterone, was low but proven to be real by the administration of deuterium-labeled DHEA and the subsequent identification and quantification of deuterium-labeled testosterone. A concentration threshold of 300 micrograms/L of DHEA glucuronide is proposed for the screening of DHEA abuse in sport, but a single replacement dose can only be detected during 8 h. Such a short detection period is the consequence of considerable first-pass hepatic metabolism and also of the high interindividual variability of circulating and urinary DHEA and DHEA sulfate concentrations. PMID:9516717

Dehennin, L; Ferry, M; Lafarge, P; Pérès, G; Lafarge, J P

1998-02-01

424

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

PubMed Central

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

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

2013-01-01

425

Performance evaluation of a wood-chip based biofilter using solid-phase microextraction and gas chromatography-mass spectroscopy-olfactometry.  

PubMed

A pilot-scale mobile biofilter was developed where two types of wood chips (western cedar and 2 in. hardwood) were examined to treat odor emissions from a deep-pit swine finishing facility in central Iowa. The biofilters were operated continuously for 13 weeks at different air flow rates resulting in a variable empty bed residence time (EBRT) from 1.6 to 7.3 s. During this test period, solid-phase microextraction (SPME) PDMS/DVB 65 microm fibers were used to extract volatile organic compounds (VOCs) from both the control plenum and biofilter treatments. Analyses of VOCs were carried out using a multidimentional gas chromatography-mass spectrometry-olfactometry (MDGC-MS-O) system. Results indicated that both types of chips achieved significant reductions in p-cresol, phenol, indole and skatole which represent some of the most odorous and odor-defining compounds known for swine facilities. The results also showed that maintaining proper moisture content is critical to the success of wood-chip based biofilters and that this factor is more important than media depth and residence time. PMID:18455390

Chen, Lide; Hoff, Steven J; Koziel, Jacek A; Cai, Lingshuang; Zelle, Brian; Sun, Gang

2008-05-01

426

Total organic carbon and gas chromatography-mass spectroscopy methods to determine total carbon and hydrocarbons in mercuric iodide single crystals  

NASA Astrophysics Data System (ADS)

Total organic carbon was determined by measuring the CO2 produced by combustion in a sealed quartz vessel. The CO2 was quantified by nondispersive IR and by titration using commercial detectors. The total organic carbon was found to be around 10–100 ?g/g in both starting materials and in single crystals. Gas chromatography-mass spectroscopy (GC/MS) measurements were made on hexane extracts of mercuric iodide (HgI2) dissolved in potassium iodide solution. Hydrocarbons starting with C10 (DIENE) and up to C26 were found. In addition, phthalates, such as diethyl and dioctyl phthalate were also found. Some of the organic compounds, for example, such hydrocarbons as branched nC16, nC20, nC21, nC22, nC23, and nC24, were present in some HgI2 materials in quantities of the order of weight ppm, but were eliminated in the purification process and were not found in the single crystals. Other organic compounds such as the phthalates were not always eliminated and were identified in the single crystals. In general, the GC/MS could identify only hydrocarbons of C10 and higher which account for only a few percent of the total organic carbon determined by oxidation.

Steinberg, S.; Kaplan, I.; Schieber, M.; Ortale, C.; Skinner, N.; van den Berg, L.

1989-11-01

427

Single drop microextraction and gas chromatography-mass spectrometry for the determination of diflufenican, mepanipyrim, fipronil, and pretilachlor in water samples.  

PubMed

An analytical method for the determination of diflufenican, mepanipyrim, pretilachlor, and fipronil in water samples was developed using single drop microextraction in the direct immersion mode and gas chromatography-mass spectrometry. A factorial fractionated design of type 2(6-1) at two levels was performed, to study the influence of experimental variables such as ionic strength, pH, agitation speed, extraction time, drop volume, and sample volume. To establish the optimal conditions for the variables that were significant, a Doehlert design was performed. The optimum conditions of extraction were 1 ?L of heptane immersed in 4.0 mL of sample with continuous agitation at 500 rpm for 30 min at room temperature. The developed method proved to have good linearity for the range studied. The detection limits were 0.07 ?g L(-1) for diflufenican, 0.03 ?g L(-1) for mepanipyrim, 0.08 ?g L(-1) for pretilachlor, and 1.39 ?g L(-1) for fipronil. The method was validated on river water samples, showing the absence of matrix effect and recoveries ranged from 90.1 to 107.8 %. The results show that the method developed is accurate, sensitive, rapid, simple, and low cost, so it is recommended for application in the analysis of these different classes of pesticides in water samples. PMID:23887887

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