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1

Rapid determination of polysaccharides in BianTi Soft Extract by spectrophotometry coupled with gas chromatography-mass spectrometry  

PubMed Central

A simple approach for the rapid determination of polysaccharides in BianTi Soft Extract using spectrophotometry coupled with gas chromatography-mass spectrometry (GC-MS) was developed. The mixed standard solution composed of D-glucose, D-mannose, galactose and D-xylose in different proportions (1.00: 1.01: 0.12: 0.05) was prepared according to the monosaccharide composition analysis of the polysaccharides by GC-MS. The determination of polysaccharides by UV-Vis spectrophotometer was performed after 35-min color reaction, in which 1 ml 5% phenol and 4 ml sulfate was used. The assay of the method validation has shown that the method was stable, reliable and feasible. Furthermore, the proposed method was successfully applied in the preparation procedure of BianTi Soft Extract, selecting out optimal decoction conditions and suitable decoction container. It suggests that the convenient method could be useful for the quality control of BianTi Soft Extract. Meanwhile, it may be an alternative for polysaccharides determination of other formulations. PMID:20668575

Zheng, Minxia; Shen, Jie; Yang, Kai; Qian, Songxiang; Feng, Sujuan

2010-01-01

2

Supersonic gas chromatography/mass spectrometry.  

PubMed

A new gas chromatography/mass spectrometry (GC/MS) system was designed and evaluated which we have named 'Supersonic GC/MS'. It is based on a modification of a commercially available GC/MS system to include a supersonic molecular beam (SMB) MS interface. In this system the standard electron ionization (EI) ion source was replaced with a fly-through EI ion source mounted in the path of the SMB. A hyperthermal surface ionization (HSI) ion source combined with a 90 degrees ion mirror (for the EI-produced ions) was also added, and placed inside the quadrupole mass analyzer in place of its original EI ion source. The 'Supersonic GC/MS' system requires 18 cm added bench space plus the addition of an air-cooled 60 L/s diffusion pump and a 537 L/min rotary pump. The system is user friendly since all the gas flow rates, heated zones, sampling and data analysis are performed the same way as the original system and are computer-controlled via the original software. Similar EI sensitivity was obtained as with the original system for hexachlorobenzene and octafluoronaphthalene, while improved EI detection limits were demonstrated for methyl stearate and eicosane due to the significant enhancement of their molecular ion abundances. A GC/MS detection limit of 500 ag for pyrene was demonstrated using HSI. Good supersonic expansion cooling was achieved with large alkanes, despite the use of a rotary pump at the nozzle chamber instead of a diffusion pump. High temperature GC/MS analysis was demonstrated for large polycyclic aromatic hydrocarbons (PAHs) including ovalene and decacyclene (ten rings). Library searches with EI mass spectra are demonstrated, and it is explained why the enhancement of the molecular ion actually improves the library search in most cases. The analysis of large phthalate esters is also described, and the improvement obtained is shown to originate from their enhanced molecular and high mass fragment ions. PMID:11344542

Amirav, A; Gordin, A; Tzanani, N

2001-01-01

3

ANALYSIS OF TECHNICAL CHLORDANE BY GAS CHROMATOGRAPHY MASS SPECTROMETRY  

EPA Science Inventory

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

4

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

E-print Network

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

Zhou, Yaoqi

5

ORGANIC WATER POLLUTANT ANALYSIS BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY  

EPA Science Inventory

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

6

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

7

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

8

Cell Wall Chemotyping for Functional Applications of PyrolysisGas Chromatography / Mass  

E-print Network

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

9

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

USGS Publications Warehouse

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

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

1977-01-01

10

Quantifying biomass composition by gas chromatography/mass spectrometry.  

PubMed

We developed a set of methods for the quantification of four major components of microbial biomass using gas chromatography/mass spectrometry (GC/MS). Specifically, methods are described to quantify amino acids, RNA, fatty acids, and glycogen, which comprise an estimated 88% of the dry weight of Escherichia coli. Quantification is performed by isotope ratio analysis with fully (13)C-labeled biomass as internal standard, which is generated by growing E. coli on [U-(13)C]glucose. This convenient, reliable, and accurate single-platform (GC/MS) workflow for measuring biomass composition offers significant advantages over existing methods. We demonstrate the consistency, accuracy, precision, and utility of this procedure by applying it to three metabolically unique E. coli strains. The presented methods will have widespread applicability in systems microbiology and bioengineering. PMID:25208224

Long, Christopher P; Antoniewicz, Maciek R

2014-10-01

11

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

12

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

PubMed

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

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

2012-09-21

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

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...

15

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

PubMed

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

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

1977-01-01

16

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

E-print Network

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

Antoniewicz, Maciek R.

17

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

E-print Network

Thermal degradation of deoxybenzoin polymers studied by pyrolysis-gas chromatography by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The polymers were synthesized Available online 29 March 2008 Keywords: Flame-retardant polymers Thermal degradation Pyrolysis-gas

18

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 ...

19

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

ERIC Educational Resources Information Center

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

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

2013-01-01

20

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

ERIC Educational Resources Information Center

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

Kusch, Peter

2014-01-01

21

Current Applications of Gas Chromatography\\/Mass Spectrometry in the Study of Organic Acids in Urine  

Microsoft Academic Search

Gas chromatography\\/mass spectrometry (GC\\/MS) is the most suitable technique for the diagnosis of disorders of organic acid metabolism, known as organic acidurias. They are inherited metabolic disorders that are characterized by an excessive amount of organic acids and their metabolites. Now in many clinical and diagnostic laboratories, automated, quantitative, and qualitative procedures for complex mixture analysis of urinary organic acids

Joanna Kauna-Czapli?ska

2011-01-01

22

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

23

DEVELOPMENTS IN DIRECT THERMAL EXTRACTION GAS CHROMATOGRAPHY-MASS SPECTROMETRY OF FINE AEROSOLS  

EPA Science Inventory

This examines thermal extraction gas chromatography-mass spectrometry (TE/GC/MS) applied to aerosols collected on filters. Several different TE/GC/MS systems as a group have speciated hundreds of individual organic constituents in ambient fine aerosols. Molecular marker source ap...

24

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

Microsoft Academic Search

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

Jose C. del Río; Patrick G. Hatcher

1998-01-01

25

Isotope-ratio-monitoring gas chromatography--mass spectrometry  

Microsoft Academic Search

A 750°C cupric-oxide-packed combustion furnace is inserted between the gas chromatographic column outlet and a GC\\/MS interface attached to a computer-controlled beam-switching isotope ratio mass spectrometer. Monitoring of Nâ and COâ ion currents due to the combustion products allows continuous measurement of ¹⁵N\\/¹⁴N or ¹³C\\/¹²C ratios, providing directly comparable isotopic analyses for all eluting compounds regardless of composition and mass

D. E. Matthews; J. M. Hayes

1978-01-01

26

Identification of two Thormählen-positive compounds from melanotic urine by gas chromatography-mass spectrometry.  

PubMed

The isolation of two Thormählen-positive compounds from the urine of a patient with malignant melanoma and the elucidation of their structure by gas chromatography-mass spectometry is described. The compounds were isolated using a poly-N-vinylpyrrolidone column and separated by preparative thin-layer chromatography. After elution they were analyzed by gas chromatography and gas chromatography-mass spectrometry as their trimethylsilyl derivatives and after hydrolysis also as their tert.-butyldimethylsilyl derivatives. The results showed the main Thormählen-positive compound A to be the glucuronide of 5-hydroxy-6-methoxyindole, whereas the minor compound AX appeared to be the glucuronide of its isomer 6-hydroxy-5-methoxyindole. PMID:7228942

Pavel, S; Muskiet, F A; Nagel, G T; Schwippelová, Z; Duchon, J

1981-03-13

27

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

PubMed

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

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

2006-08-01

28

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

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

29

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

PubMed Central

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

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

2014-01-01

30

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

PubMed

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

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

2015-01-01

31

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

Microsoft Academic Search

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

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

2002-01-01

32

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

33

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

34

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

Microsoft Academic Search

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

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

1968-01-01

35

An integrated method for spectrum extraction and compound identification from gas chromatography\\/mass spectrometry data  

Microsoft Academic Search

A method is presented for extracting individual component spectra from gas chromatography\\/mass spectrometry (GC\\/MS) data files\\u000a and then using these spectra to identify target compounds by matching spectra in a reference library. It extends a published\\u000a “model peak” approach which uses selected ion chromatograms as models for component shape. On the basis of this shape, individual\\u000a mass spectral peak abundance

S. E. Stein

1999-01-01

36

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

37

Gas chromatography–mass spectrometry associated global analysis of rice root exudates under aseptical conditions  

Microsoft Academic Search

Components of rice root exudates were surveyed by gas chromatography–mass spectrometry (GC-MS) and the effect of phosphate (P) starvation was investigated. Rice seedlings were aseptically grown in controlled environments under P-supplied (+P) or P-deficient (–P) conditions. Root exudates were collected from the culture solution 4 and 8?days after treatment (D4 and D8, respectively), which contain the first and second 4-day

Katsumasa Suzuki; Keiki Okazaki; Keitaro Tawaraya; Mitsuru Osaki; Takuro Shinano

2009-01-01

38

Evaluation of plasma enzyme activities using gas chromatography–mass spectrometry based steroid signatures  

Microsoft Academic Search

The simultaneous quantification of 65 plasma steroids, including 22 androgens, 15 estrogens, 15 corticoids and 13 progestins, was developed using gas chromatography-mass spectrometry (GC–MS). The extraction efficiency of the catechol estrogens was improved by the addition of l-ascorbic acid in several steps. All steroids, as their trimethylsilyl derivatives, were well separated with good peak shapes within a 50min run. The

Young Wan Ha; Ju-Yeon Moon; Hyun-Jin Jung; Bong Chul Chung; Man Ho Choi

2009-01-01

39

Determination of hydroxyl radicals using salicylate as a trapping agent by gas chromatography-mass spectrometry  

Microsoft Academic Search

Objectives: To establish a sensitive method for measuring hydroxyl radical formation in biological systems using salicylate as probe.Methods: Salicylate hydroxylation products and related aromatic compounds were extracted and converted to trimethylsilyl (TMS) derivatives. The derivatives were analyzed by gas chromatography-mass spectrometry (GC-MS). Quantitation was achieved by selected-ion-recording (SIR) with benzoic acid (ring-D5) as an internal standard.Results: All compounds were well

Xiaoping Luo; Denis C. Lehotay

1997-01-01

40

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

41

Gas chromatography-mass spectrometry evidence for several endogenous auxins in pea seedling organs  

Microsoft Academic Search

Qualitative analysis by gas chromatography-mass spectrometry (GC-MS) of the auxins present in the root, cotyledons and epicotyl of 3-dold etiolated pea (Pisum sativum L., cv. Alaska) seedlings has shown that all three organs contain phenylacetic acid (PAA), 3-indoleacetic acid (IAA) and 4-chloro-3-indoleacetic acid (4Cl-IAA). In addition, 3-indolepropionic acid (IPA) was present in the root and 3-indolebutyric acid (IBA) was detected

Elnora A. Schneider; Clement W. Kazakoff; Frank Wightman

1985-01-01

42

Characterization of gamma irradiated petrolatum eye ointment base by headspace–gas chromatography–mass spectrometry  

Microsoft Academic Search

The effects of gamma irradiation on petrolatum eye ointment base (EOB) and its ingredients (white petrolatum, liquid paraffin, and wool fat) were studied at different irradiation doses. Forty-one volatile radiolysis products were detected and identified by a combined system of headspace–gas chromatography–mass spectrometry (HS–GC–MS). The characteristics of the radiolysis products and the degradation pathway were discussed in each case, respectively.

Lan Hong; Hans Altorfer

2002-01-01

43

Search on ruggedness of fast gas chromatography–mass spectrometry in pesticide residues analysis  

Microsoft Academic Search

In this study, suitability of fast gas chromatography–mass spectrometry (GC–MS) on a narrow-bore column with a programmed temperature vaporizer for the analysis of pesticide residues in non-fatty food was evaluated. The main objectives were ruggedness and stability of chromatographic system with regards to co-extractives injected. The chromatographic matrix induced response enhancement was found to be strongly dependent on the concentration

Michal Kirchner; Eva Matisová; Robert Otrekal; Andrea Hercegová; Jaap de Zeeuw

2005-01-01

44

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

Microsoft Academic Search

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

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

2008-01-01

45

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

46

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

47

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

Microsoft Academic Search

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

PATRICK G. HATCHER

1998-01-01

48

Identification of volatile compounds in poultry manure by gas chromatography-mass spectrometry.  

PubMed

Volatile components in poultry manure were isolated by freeze vacuum distillation and continuous extraction, and 72 compounds were identified by gas chromatography and gas chromatography-mass spectrometry. Branched alipathic alcohols, many esters, dimethyl trisulphide and alkanamides were detected for the first time. Carboxylic acids, sulphides, alkanamides, phenols and indoles were formed during rotting. Judging from the ratio of concentration to the threshold value (detectable amount of odour) of each component detected in poultry manure, the most important odorous components were butyric acid, 3-methylbutyric acid, dimethyl trisulphide, indole and skatole. PMID:3558630

Yashuhara, A

1987-01-30

49

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

50

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

SciTech Connect

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

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

1996-03-01

51

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

52

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

53

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

PubMed

An effective method was established for the simultaneous determination of residual glycol ethers in leather and leather products by gas chromatography/mass spectrometry. Glycol ethers in leather and leather products were ultrasonically extracted at 45 °C, using ethyl acetate as the extraction solvent. The extracts were purified by solid phase extraction (SPE) columns, and then analyzed by gas chromatography/mass spectrometry in selected ion monitoring mode. The content of each analyte was calibrated by external standard method. The limit of detection of ethylene glycol ethyl ether (EGEE) was 0. 10 mg/kg under the condition of signal to noise (S/N) of 3 and the limits of the other 11 glycol ethers were all less than 0.05 mg/kg. The spiked recoveries varied from 81. 2% to 95. 5% at three different spiked levels with the relative standard deviations (RSDs) ranged from 1.4% to 6. 6%. The proposed method is simple, rapid and accurate, with the limits of detection much less than the requirements of the Regulation Concerning Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) of European Union. It is applicable to the determination of residual glycol ethers in leather and leather products, and provides a reference for the relevant testing standards. PMID:25507726

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

2014-08-01

54

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

PubMed

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

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

2014-08-01

55

Headspace analysis of engine oil by gas chromatography/mass spectrometry.  

PubMed

This study establishes the rationale necessary for determining the time to change engine oil. This is based on identifying gaseous components in new and used automobile lubricants. Key compounds, so-called "signature", are separated and identified qualitatively by coupled gas chromatography/mass spectrometry. Volatile antioxidants at zero miles and fuel contaminants at low mileage are observed in the headspace of engine oil. Several oxidative degradation components have been positively identified in the used oil, which include the following: acetaldehyde, acetone, butanal, 2-propanol, acetic acid, 2-hexanol, benzoic acid, benzaldehyde, and 1-pentanol. This study strongly suggests that the status of lubricating oil can be determined by the analysis of the gas phase above the oil. Most importantly, it opens the possibility of performing conditional maintenance of the combustion engine based on information obtained from gas sensors. PMID:11305675

Levermore, D M; Josowicz, M; Rees, W S; Janata, J

2001-03-15

56

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

PubMed

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

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

2014-08-01

57

Group separation and gas chromatography--mass spectrometry of conjugated steroids in plasma.  

PubMed

A method is described for analysis of metabolic profiles of conjugated steroids in plasma. Steroids are extracted by Amberlite XAD-2 or Sep-Pak C18 cartridges at 60 64 C in the presence of triethylamine sulphate and separated into unconjugated neutral and phenolic compounds, glucuronide, monosulphate and disulphate conjugate groups by chromatography on the lipophilic strong anion exchanger triethylaminohydroxypropyl Sephadex LH-20 (TEAP-LH-20). The conjugate moiety is hydrolyzed by brief enzymatic or solvolytic procedures and released steroids are separated into a neutral and a phenolic fraction on TEAP-LH-20. The O-methyloxime and trimethylsilyl ether derivatives of the steroids are analyzed by glass capillary column gas liquid chromatography and gas chromatography mass spectrometry. Examples of the application of the method to analysis of conjugated steroids in plasma from pregnant women are given. PMID:6827836

Axelson, M; Sahlberg, B L

1983-03-01

58

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

59

Keto acid profiling analysis as ethoxime/tert-butyldimethylsilyl derivatives by gas chromatography-mass spectrometry.  

PubMed

Organic acids, including keto acids, are key intermediates of central pathways in cellular metabolism. In this study, a comprehensive and reliable method was developed and optimized for the simultaneous measurement of 17 keto acids in various biological samples. The keto acids were converted to solvent extractable forms by ethoximation followed by tert-butyldimethylsilylation for direct analysis by gas chromatography-mass spectrometry in selected ion monitoring mode. The proposed method was precise (0.05-8.3, % RSD) and accurate (-10.5 to 5.3, % RE) with low limit of detection (0.01-0.5ng/mL) and good linearity (r>0.995) in the range of 0.01-5.0?g/mL. This was suitable for profiling analysis of targeted keto acids in human plasma, urine and rat brain tissue. PMID:23270938

Nguyen, Duc-Toan; Lee, Gwang; Paik, Man-Jeong

2013-01-15

60

Gas chromatography-mass spectrometric identification of iodine species arising from photo-chemical vapor generation  

NASA Astrophysics Data System (ADS)

Ultraviolet irradiation of aqueous solutions of iodide/iodate ion containing low molecular weight organic acids generates volatile iodine species that are amenable to detection by atomic spectrometry. In the presence of formic, acetic or propionic acids, photo-chemical generation results in the formation of HI, methyl- and ethyl-iodide respectively, the latter two products being directly identified by gas chromatography-mass spectrometry. Deuterium and 13C-labeled reagents were employed to elucidate the provenance of the alkyl group. Use of 13CH 3-COOH produced 13CH 3-I; deuterated acetic acid (D 3C-COOD) resulted in the formation of CD 3-I. These observations indicate direct transfer of the alkyl group from the carboxylic acid to iodide, consistent with the suggestion that the mechanism of synthesis involves radical induced reactions.

Grinberg, Patricia; Mester, Zoltan; D'Ulivo, Alessandro; Sturgeon, Ralph E.

2009-07-01

61

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

62

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

PubMed Central

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

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

2013-01-01

63

Structure and structural diversity in resinites as determined by pyrolysis-gas chromatography-mass spectrometry  

SciTech Connect

Pyrolysis-gas chromatography-mass spectroscopy (Py-GC-MS) is a useful technique for the rapid characterization of resinites, especially when used in conjunction with in-situ methylation procedures, which permit chromatographic analysis of acidic components without complex sample preparation. Although significant diversity exists in resinite structures, the majority of resinites may be classified into one of three basic structural groups. Resinites from the largest and most important of these may be further subdivided on the basis of specific structural characteristics into three subclasses. Within these classes, details of specific composition may vary significantly between samples as a consequence of differences in botanical origin and/or level of maturation, but sufficient common structural characteristics exist within these classes to validate application of such a classification system. 13 refs., 3 figs., 1 tab.

Anderson, K.B.; Winans, R.E.

1991-01-01

64

[Structure determination of alkyd resins by simultaneous pyrolysis methylation gas chromatography-mass spectometry].  

PubMed

Several types of alkyd resins have been analyzed by simultaneous pyrolysis methylation gas chromatography mass spectrometry (SPM-GC-MS). The samples were mixed with tetramethylammonium hydroxide, and the process included simultaneous pyrolysis derivatization and mass spectrometry determination. SPM-GC-MS conditions: a vertical microfurnace-type pyrolyzer was directly attached to a gas chromatograph-mass spectrometer. About 20 ug of the mixed alkyd resin sample was introduced into the center of the pyrolyzer at 450 degrees C under the flow of helium carrier gas. The inlet mode was split with an injection interval of 10 s and the inlet pressure was 82.7 kPa. The gas chromatograph was fitted with a fused-silica capillary column ( SE-54 30 m x0.25 mm i.d. x 0.25 um). Temperature program settings were: initial temperature, 40 degrees C, hold 2 min; increase at 6 degrees C min 1 to 220 degrees C, hold 14 min; increase at 10 degrees C min 1 to 280 degrees C, hold 8 min. All pyrolysis products referred to were identified by mass spectrometry. The temperature of the ion source was 210 degrees C and that of the transfer line was 250 degrees C. The technique could give additional information about the composition of the dibasic acids, polyols, six types of drying oils, and modified alkyd resins. The method is sensitive, accurate, convenient, and involves minimal sample manipulation. PMID:12549427

Cao, J Y; Fu, D H; Zhang, F; Liang, D

2000-09-01

65

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

66

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

67

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...

68

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

EPA Science Inventory

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

69

Study on the photostability of guaiazulene by high-performance liquid chromatography/mass spectrometry and gas chromatography/mass spectrometry.  

PubMed

The photostability of guaiazulene (1,4-dimethyl-7-isopropylazulene; GA), a natural azulenic compound used in cosmetic and health-care products, as well as in pharmaceutical preparations, was investigated in solution (methanol, ethanol, acetonitrile), by different techniques: gas chromatography/mass spectrometry (GC/MS) and high-performance liquid chromatography combined with atmospheric pressure chemical ionization mass spectrometry and UV detection (LC/APCI-MS and HPLC/UV). A solar simulator (xenon-arc lamp) was used as UV-A radiation source. The study involved: monitoring compound decomposition, identifying products of photodegradation (PPs), assessing the role of oxygen and evaluating the kinetics of the process. Minor PPs are volatile compounds and were characterized by GC/MS, while oligomeric polyoxygenated compounds, tentatively characterized on the basis of MS and MS/MS spectra, were found to be the main photoproducts. The photodegradation was found to be enhanced by the presence of oxygen; nevertheless, determination of the singlet oxygen quantum yield for GA gave a lower value than that for the reference standard Rose Bengal. The obtained results and the developed stability-indicating methods (GC/MS and LC/MS) are of interest for stability studies and/or quality control purposes of GA as raw material or cosmetic products. PMID:18680092

Fiori, Jessica; Gotti, Roberto; Albini, Angelo; Cavrini, Vanni

2008-09-01

70

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

PubMed Central

A sensitive and selective gas chromatography-mass spectrometry (GC-MS) method was developed and validated for the determination of morphine and codeine in human urine. The GC-MS conditions were developed. The analysis was carried out on a HP-1MS column (30?m × 0.25?mm, 0.25??m) with temperature programming, and Helium was used as the carrier gas with a flow rate of 1.0?mL/min. Selected ion monitoring (SIM) mode was used to quantify morphine and codeine. The derivation solvent, temperature, and time were optimized. A mixed solvent of propionic anhydride and pyridine (5?:?2) was finally used for the derivation at 80°C for 3?min. Linear calibration curves were obtained in the concentration range of 25–2000.0?ng/mL, with a lower limit of quantification of 25?ng/mL. The intra- and interday precision (RSD) values were below 13%, and the accuracy was in the range 87.2–108.5%. This developed method was successfully used for the determination of morphine and codeine in human urine for forensic identification study. PMID:24222889

Zhang, Xiaoqian; Cao, Gaozhong; Hu, Guoxin

2013-01-01

71

Determination of endogenous ethanol in blood and breath by gas chromatography-mass spectrometry.  

PubMed

We describe methods for the determination of endogenous ethanol in biological specimens from healthy abstaining subjects. The analytical methods were headspace gas chromatography (GC) for plasma samples and gas chromatography-mass spectometry (GC/MS) with deuterium labelled species 2H3-ethanol and 2H5-ethanol as internal standards for breath analysis. Ethanol in rebreathed air was about 10% higher than in directly analysed end-expired alveolar air. Known volumes of rebreathed air were passed through a liquid-N2 freeze trap and the volatile constituents of breath were concentrated prior to analysis by GC or GC/MS. Besides endogenous ethanol, peaks were seen on the chromatograms for methanol, acetone and acetaldehyde as well as several as yet unidentified substances. The endogenous alcohols ethanol and methanol were confirmed from their mass chromatograms and the GC/MS profile also indicated the presence of endogenous propan-1-ol. The concentration of endogenous ethanol in plasma showed wide inter-subject variations ranging from below detection limits to 1.6 micrograms/ml (34.8 mumol/l) and with mean +/- SD of 0.39 +/- 0.45 micrograms/ml (8.5 +/- 9.8 mumol/l). We aim to characterise further the role of endogenous ethanol with the main focus on dynamic aspects such as the rate of formation and turnover. PMID:6634839

Jones, A W; Mårdh, G; Anggård, E

1983-01-01

72

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

73

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

74

Determination of methomyl in the stomach contents of baited wildlife by gas chromatography-mass spectrometry.  

PubMed

The poisoning of wildlife with fly-bait containing the active ingredient methomyl is an intentional and illegal act in many jurisdictions. A case of 2 animals poisoned by methomyl through consumption of tainted bait at multiple stations is described. Although thermally and ultraviolet-labile, methomyl can be identified by gas chromatography-mass spectrometry and is detected in abundance in bait samples; however, it is not readily observed in tissues, owing to its rapid metabolism and elimination. The application of derivatizing functionalities, such as trimethylsilyl groups, stabilizes the methomyl-oxime metabolite to facilitate its detectability during exposure to the relatively harsh conditions of gas chromatography. This brief communication reports on the analytical detection of methomyl in baits and biological samples from poisoned wildlife. Essential to the case were the added determination of a fly-bait coactive ingredient, (Z)-9-tricosene, and identification of a chemical indicator, caffeine, to confirm both the type of pesticide product involved in the poisoning incident and the vehicle used to perpetrate its delivery. PMID:24105381

Buchweitz, John P; Bokhart, Mark; Johnson, Margaret; Lehner, Andreas

2013-11-01

75

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

76

Identification of tartary buckwheat tea aroma compounds with gas chromatography-mass spectrometry.  

PubMed

Tartary buckwheat tea, which is an important and healthy product, has a distinct malty aroma. However, its characteristic aroma compounds have not been elucidated. The aims of present study were identification and quantification of its aroma compounds. The analyses were performed by gas chromatography-mass spectrometry (GC-MS) after 3 different isolation techniques. Seventy-seven compounds were identified. Among these compounds, 35 were quantified by available standards. The compounds with a high probability of contribution to the tartary buckwheat tea aroma (OAV ? 10) were as follows: 2,5-dimethyl-4-hydroxy-3(2H)-furanone, nonanal, 2,3-diethyl-5-methylpyrazine, benzeneacetaldehyde, maltol, 2,5-dimethylpyrazine, 2-ethyl-5-methylpyrazine, trimethylpyrazine. Some nutritional and bioactive compounds were also identified in this study, such as linoleic acid, niacin, vanillic acid, 7-hydroxycoumarin, butylated hydroxytoluene. Practical Application: Tartary buckwheat, one type of buckwheat, has gained much attention from nutritionists and medical doctors in recent years. It is rich in rutin, quercetin, and other nutrients that are good for health. Tartary buckwheat-based product such as tartary buckwheat tea is an important and popular healthy product in China, Japan,South Korea, European countries as well as in American countries. It has a distinct malty aroma. The present study first identified and quantified of its aroma compounds. The results will draw attention to other researchers in food flavor and buckwheat filed. PMID:22417522

Qin, Peiyou; Ma, Tingjun; Wu, Li; Shan, Fang; Ren, Guixing

2011-08-01

77

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

PubMed

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

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

2011-06-01

78

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

2013-08-01

79

Gas chromatography mass spectrometry based metabolic profiling reveals biomarkers involved in rice-gall midge interactions.  

PubMed

The Asian rice gall midge (Orseolia oryzae Wood-Mason) is a serious pest of rice that causes huge loss in yield. While feeding inside the susceptible host, maggots secrete substances that facilitate the formation of a hollow tube-like structure called gall and prevent panicle formation. The present investigation was carried out to get an account of biochemical changes occurring in the rice plant upon gall midge feeding. Metabolic profiling of host tissues from three rice varieties, namely, TN1, Kavya, and RP2068, exposed to gall midge biotype 1 (GMB1), was carried out using gas chromatography mass spectrometry (GC-MS). TN1 and GMB1 represented compatible interaction, while Kavya and GMB1 as well as RP2068 and GMB1 represented incompatible interactions. The current study identified several metabolites that could be grouped as resistance, susceptibility, infestation, and host features based on their relative abundance. These may be regarded as biomarkers for insect-plant interaction in general and rice-gall midge interaction in particular. PMID:25059749

Agarrwal, Ruchi; Bentur, Jagadish Sanmallappa; Nair, Suresh

2014-09-01

80

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

PubMed

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

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

2012-09-28

81

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

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

82

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

PubMed

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

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

2012-04-01

83

Baseline correction method using an orthogonal basis for gas chromatography/mass spectrometry data.  

PubMed

A baseline correction method that uses basis set projection to estimate spectral backgrounds has been developed and applied to gas chromatography/mass spectrometry (GC/MS) data. An orthogonal basis was constructed using singular value decomposition (SVD) for each GC/MS two-way data object from a set of baseline mass spectra. A novel aspect of this baseline correction method is the regularization parameter that prevents overfitting that may produce negative peaks in the corrected mass spectra or ion chromatograms. The number of components in the basis, the regularization parameter, and the mass spectral range from which the spectra were sampled to construct the basis were optimized so that the projected difference resolution (PDR) or signal-to-noise ratio (SNR) was maximized. PDR is a metric similar to chromatographic resolution that indicates the separation of classes in a multivariate data space. This new baseline correction method was evaluated with two synthetic data sets and a real GC/MS data set. The prediction accuracies obtained by using the fuzzy rule-building expert system (FuRES) and partial least-squares-discriminant analysis (PLS-DA) as classifiers were compared and validated through bootstrapped Latin partition (BLP) between data before and after baseline correction. The results indicate that baseline correction of the two-way GC/MS data using the proposed methods resulted in a significant increase in average PDR values and prediction accuracies. PMID:21823628

Xu, Zhanfeng; Sun, Xiaobo; Harrington, Peter de B

2011-10-01

84

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

PubMed

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

Baumer, Ursula; Dietemann, Patrick

2010-06-01

85

Gas chromatography/mass spectrometry analysis of Laurus nobilis essential oil composition of northern Cyprus.  

PubMed

The chemical composition of the essential oil isolated from the leaves of the Laurus nobilis plant (from the Northern Cyprus Mountains) by hydrodistillation was analyzed by gas chromatography-mass spectrometry. Of the 81 compounds representing 98.74% of total oil, monocyclic monoterpenes such as 1,8-cineole (58.59%), alpha-terpinyl acetate (8.82%), and terpinene-4-ol (4.25%) were the main components. Bicyclic monoterpenes such as alpha- and beta- pinene (3.39-3.25%) and sabinene (3.32%) were also identified. The acyclic monoterpenes linalool (0.19%) and myrcenol (0.10%) were present in smaller amounts, and so were the sesquiterpenes. o-Cymene (1.30%) and p-cymene (1.83%) were the main, while cumin aldehyde (0.24%), dimethylstyrene (0.08%), eugenol (0.16%), methyl eugenol (0.05%), and carvacrol (0.05%) were found as minor, aromatic compounds of laurel oil. PMID:18158847

Yalçin, Hasan; Anik, Mehtap; Sanda, Murat Aydin; Cakir, Ahmet

2007-12-01

86

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

87

Characterization of volatile organic compounds by thermal desorption/gas chromatography/mass spectrometry  

SciTech Connect

Carbonaceous triple sorbent traps (TSTs) have been widely used to collect and concentrate volatile organic compounds (VOCs) in vapor phase samples for subsequent GC/MS analysis. Recently, this laboratory has been involved in sampling and analyzing VOCs collected from various emission sources, including headspace samples from underground storage tanks at the Department of Energy`s Hanford site, in Richland, Washington. In order to evaluate the sampling adequacy and to assess any health-related impact based on the analysis results, a validated method must be employed. Therefore, the main objective of this study was to develop a methology for thermal desorption/gas chromatography/mass spectrometry (TD/GC/MS) determination of VOCs in the vapor phase samples collected on Carbotrap C/Carbotrap/Carbosieve S III triple sorbent traps. Techniques used in method validation included VOC standard generation, thermal desorption efficiency, reproducibility of spiking on and recovery from TST, use of internal standards, detection limits determination, linearity and reproducibility of calibration.

Ma, Cheng-Yu; Skeen, J.T.; Dindal, A.B. [Oak Ridge National Lab., TN (United States)] [and others

1995-12-31

88

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

PubMed

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

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

2015-01-01

89

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

NASA Astrophysics Data System (ADS)

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

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

2009-07-01

90

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

PubMed Central

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

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

2014-01-01

91

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

PubMed

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

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

2014-11-01

92

Metabolomics research on the hepatoprotective effect of Angelica sinensis polysaccharides through gas chromatography-mass spectrometry.  

PubMed

Angelica sinensis polysaccharides (ASP) have an established hepatoprotective effect, but the mechanism for this effect remains unclear. A novel approach using biochemical parameters coupled with metabolomics based on gas chromatography-mass spectrometry (GC-MS) and chemometrics was established in this study to explain the hepatoprotective effect mechanism of ASP. The superoxide dismutase activity, malonaldehyde content, alanine aminotransferase, aspartate aminotransferase, and ?-glutamyl transpeptidase in plasma were measured. Pathological changes in the liver were observed. Plasma and liver homogenate obtained from mice were analyzed using GC-MS. Distinct changes in metabolite patterns in the plasma and liver homogenate after being induced by carbon tetrachloride and drug intervention were observed using principal component analysis (PCA) and partial least squares-discriminate analysis (PLS-DA). Potential biomarkers were found using PLS-DA and T-test. The results of the pathological changes observed in the liver, the biochemical parameters in plasma, and the metabolomics of the plasma and liver homogenate all showed that liver injury was successfully reproduced, ASP exhibited hepatoprotective effect, and the medium dose of ASP exhibited the best. Nine endogenous metabolites in the liver homogenate and ten endogenous metabolites in the plasma were all considered as potential biomarkers. They were considered to be in response to hepatoprotective effects of ASP involved in the amino acids metabolism, energy metabolism, and lipids metabolism. Therefore metabolomics is a valuable tool in measuring the efficacy and mechanisms of action of traditional Chinese medicines. PMID:25464094

Ji, Peng; Wei, Yanming; Sun, Hongguo; Xue, Wenxin; Hua, Yongli; Li, Pengling; Zhang, Wenquan; Zhang, Ling; Zhao, Haifu; Li, Jinxia

2014-10-18

93

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

PubMed

An analytical approach was developed to determine nonylphenol (NP), octylphenol (OP), nonylphenol ethoxylates (NPEO(n)) and octylphenol ethoxylates (OPEO(n)) in leather samples involving the conversion of NPEO(n) and OPEO(n) into the corresponding NP and OP. The four targets were extracted from samples using ultrasonic-assisted acetonitrile extraction. NP and OP in the extracts were directly isolated with hexane and quantitatively determined with 4-n-nonylphenol as internal standard by gas chromatography-mass spectrometry (GC-MS). For NPEO(n) and OPEO(n) in the extracts, they were first converted into NP and OP with aluminum triiodide as cleavage agent, and the yielded NP and OP were determined by GC-MS. The contents of NPEO(n) and OPEO(n) were calculated by normalizing to NPEO(9) and OPEO(9), respectively. This method was properly validated and the real sample tests revealed the pollution significance of leather by NPEO(n) and OPEO(n). PMID:21067757

Ma, He-Wei; Cheng, Ya

2010-12-10

94

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

PubMed Central

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

2014-01-01

95

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

PubMed

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

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

2013-01-01

96

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

2013-06-01

97

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

EPA Science Inventory

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

98

Determination of amphetamine-type stimulants in oral fluid by solid-phase microextraction and gas chromatography–mass spectrometry  

Microsoft Academic Search

A method for the simultaneous identification and quantification of amphetamine (AMP), methamphetamine (MET), fenproporex (FEN), diethylpropion (DIE) and methylphenidate (MPH) in oral fluid collected with Quantisal™ device has been developed and validated. Thereunto, in-matrix propylchloroformate derivatization followed by direct immersion solid-phase microextraction and gas chromatography–mass spectrometry were employed. Deuterium labeled AMP was used as internal standard for all the stimulants

Daniele Z. Souza; Paula O. Boehl; Eloisa Comiran; Kristiane C. Mariotti; Flavio Pechansky; Paulina C. A. V. Duarte; Raquel De Boni; Pedro E. Froehlich; Renata P. Limberger

2011-01-01

99

Selected ion monitoring gas chromatography\\/mass spectrometry of 1,2-diacylglycerol tert -butyldimethylsilyl ethers derived from glycerophospholipids  

Microsoft Academic Search

Selected ion monitoring was used in conjunction with gas chromatography\\/mass spectrometry to analyzetert-butyldimethylsilyl ethers (tert-BDMS) of 1,2-diacyl-sn-glycerols derived from naturally occurring glycerophospholipids, including those ofEscherichia coli, soybean, egg yolks and porcine liver. First, the fatty acid composition of the unknown glycerophospholipid was determined\\u000a by gasliquid chromatography (GLC) and, based on that, the fatty acids (mostly >0.5 wt%) were selected for

Toshiaki Ohshima; Chiaki Koizumi

1991-01-01

100

Detection of biomarkers in the organic matter of rocks from the Romashkinskoe oil field using gas chromatography-mass spectrometry  

Microsoft Academic Search

Polycyclic hydrocarbons (biomarkers) were detected in the organic matter of Paleozoic and pre-Paleozoic rocks from the Romashkinskoe\\u000a oil field in the Volga-Ural region using gas chromatography-mass spectrometry. Coefficients were calculated from the ratio\\u000a between tetra- and pentacyclic hydrocarbons, and the facial genetic types, possible generation sources, and evolution transformation\\u000a conditions of the initial organic matter were determined from the array

N. S. Sharipova; G. K. Budnikov; B. V. Uspenskii; G. P. Kayukova

2010-01-01

101

Validation of an analytical procedure to measure trace amounts of neurosteroids in brain tissue by gas chromatography–mass spectrometry  

Microsoft Academic Search

A selective and extremely sensitive procedure has been developed and optimized, using high-performance liquid chromatography (HPLC), specific derivatization and gas chromatography–mass spectrometry (GC–MS), to simultaneously quantify very small amounts of different neurosteroids from rat brain. Unconjugated and sulfated steroids in brain extracts were separated by solid-phase extraction. The unconjugated fraction was further purified by HPLC, the steroids being collected in

Philippe Liere; Yvette Akwa; Sébastien Weill-Engerer; Bernard Eychenne; Antoine Pianos; Paul Robel; Jan Sjövall; Michaël Schumacher; Etienne-Emile Baulieu

2000-01-01

102

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

PubMed Central

Arthrobacter sp. SPG transformed indole completely in the presence of an additional carbon source. High performance liquid chromatography and gas chromatography-mass spectrometry detected indole-3-acetic acid, indole-3-glyoxylic acid, and indole-3-aldehyde as biotransformation products. This is the first report of the formation of indole-3-acetic acid, indole-3-glyoxylic acid, and indole-3-aldehyde from indole by any bacterium. PMID:25548566

Arora, Pankaj Kumar

2014-01-01

103

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

Microsoft Academic Search

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

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

2002-01-01

104

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

Microsoft Academic Search

To establish a method for the routine analysis of carboxyhemoglobin (COHb) in autopsy materials including those which have undergone postmortem changes, e.g. thermo-coagulation, putrifaction and contamination, an automated head-space gas chromatography\\/mass spectrometry (GC\\/MS) analysis was utilized. The procedure consisted of preparation of the sample in a vial and a carbon monoxide (CO) saturated sample, for estimation of hemoglobin content, in

Shigeki Oritani; Bao-Li Zhu; Kaori Ishida; Keiko Shimotouge; Li Quan; Masaki Q Fujita; Hitoshi Maeda

2000-01-01

105

Detection and identification of carprofen and its in vivo metabolites in greyhound urine by capillary gas chromatography–mass spectrometry  

Microsoft Academic Search

Rimadyl® (carprofen) was administered orally to the racing greyhound at a dose of 2.2 mg kg?1. Following both alkaline and enzymatic hydrolysis, postadministration urine samples were extracted by mixed mode solid-phase extraction (SPE) cartridges to identify target analyte(s) for forensic screening and confirmatory analysis methods. The acidic isolates were derivatised as trimethylsilyl ethers (TMS) and analysed by gas chromatography–mass spectrometry

M. C. Dumasia; A. Ginn; W. Hyde; J. Peterson; E. Houghton

2003-01-01

106

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

PubMed

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

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

1980-04-01

107

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

Microsoft Academic Search

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\\u000a molecular ion to fragment ions representing the fatty acid moiety of the wax esters were measured, providing additional resolution\\u000a to the analysis of wax esters. The C21?C32 wax esters are composed of complex

Marlèn H. A. Dekker; Theunis Piersma; Jaap S. Sinninghe Damsté

2000-01-01

108

Analysis of fragrance composition in three cultivars of Osmanthus fragrans Albus group flower by gas chromatography-mass spectrometry  

Microsoft Academic Search

With supercritical CO2 fluid extraction(SCFE), essential oil was extracted from three cultivars of Xianning osmanthus. The fresh osmanthus flower\\u000a was processed with a petroleum ether digestion method to produce the extractum. The yields of essential oil and extractum\\u000a were 0.19 % and 0.13 % (m\\/m) respectively. The essential oil and fragrance composition and content extracted were analyzed with gas chromatography-mass

Fafang Li; Qizhi Huang

2011-01-01

109

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

110

Determination of linear alkylbenzenes in fish tissue by gel permeation chromatography and gas chromatography–mass spectrometry  

Microsoft Academic Search

A gel permeation chromatographic (GPC) procedure is described for separation of the long-chain linear alkylbenzenes (LABs) from fish muscle tissues. This technique was found to remove the matrix interference significantly and thereby improve the sensitivity of detection of LABs in the extracts. Gas chromatography–mass spectrometry (GC–MS) was then used to quantitate LABs in different species of fish and also fish

M. Indira Venkatesan; Terrence Northrup; Charles R Phillips

2002-01-01

111

Determination of organoarsenic warfare agents in sediment samples from Skagerrak by gas chromatography-mass spectrometry.  

PubMed

In 1945 the Norwegian authorities gave permission to scuttle ships loaded with captured chemical ammunition on board in an area approximately 14x4 km in size, 25 nautical miles south-east of Arendal. An investigation was carried out in 2002 to inspect four wrecks by using a remote-operated vehicle with video cameras. The Norwegian Defence Research Establishment (Forsvarets forskningsinstitutt, FFI) carried out the project on behalf of the Norwegian Pollution Control Authority (SFT). Sediment samples were collected at eight positions around each wreck. One of the wrecks was broken up into several smaller parts. Here sediments were collected at one additional position close to one of the parts. From each position, at least two sediment cores were taken up to the surface. One of the cores from each position was sliced into three parts that were immediately frozen. The other whole cores were frozen on board the ship and transported back to the laboratory in a freezer. In total, sediment samples from 33 different locations were collected and analysed for organoarsenic warfare agents and some of their decomposition products by gas chromatography-mass spectrometry (GC-MS) after derivatisation with 1-propanethiol. Most of the identified organoarsenic compounds found in the sediment samples are parts of the arsine oil mixture produced by Germany during World War II. The compounds were found both close to the wreck and at a somewhat longer distance from the wrecks. The highest concentrations were found in a sediment sample collected close to a bomb seen on the seabed. The organoarsenic warfare agents adamsite or lewisite were not found in any of the samples. Lewisite is not reported to have been produced during World War II, but was nevertheless looked for in the samples. PMID:15993928

Tørnes, John Aasulf; Opstad, Aase Mari; Johnsen, Bjørn Arne

2006-03-01

112

Simultaneous determination of dimethylamphetamine and its metabolites in rat hair by gas chromatography-mass spectrometry.  

PubMed

In order to study the disposition of dimethylamphetamine (DMAP) and its metabolites, DMAP N-oxide, methamphetamine (MA) and amphetamine (AP), from plasma to hair in rats, a simultaneous determination method for these compounds in biological samples using gas chromatography-mass spectrometry with selected ion monitoring (GC-MS-SIM) was developed. As DMAP N-oxide partially degrades to DMAP and MA during GC-MS analysis, it was necessary to avoid conditions which co-extract the N-oxide in the sample preparation so as to assure no contribution of artifactual products from DMAP N-oxide in the detection of the other compounds. For confirmation of the satisfactory separation of DMAP N-oxide from the others, the internal standards used for quantification were labeled with different numbers of deuterium atoms. Determination of unchanged DMAP was performed without any derivatization, that of DMAP N-oxide was carried out after conversion into trifluoroacetyl-MA by reaction with trifluoroacetic anhydride, and MA and AP were quantified after trifluoroacetyl-derivatization. After intraperitoneal administration of DMAP HCI to pigmented hairy rats (5 mgkg(-1) day(-1), 10 days, n=3), concentrations of DMAP and its metabolites in urine, plasma and hair were measured by GC-MS-SIM. The area under the concentration versus time curves (AUCs) of DMAP, DMAP N-oxide, MA and AP in the plasma were 397.2+/-97.5, 279.7+/-68.3, 18.4+/-1.2 and 15.9+/-2.2 microg min ml(-1), while their concentrations in the hair newly grown for 4 weeks after administration were 4.82+/-0.67. 0.45+/-0.09, 3.25+/-0.36 and 0.89+/-0.05 ng mg(-1), respectively. This fact suggested that the incorporation tendency of DMAP N-oxide from plasma into hair was distinctly low in comparison with the other compounds. PMID:10872586

Kikura, R; Nakahara, Y; Kojima, S

2000-05-12

113

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

114

Serum metabolic profiling of human gastric cancer based on gas chromatography/mass spectrometry  

PubMed Central

Research on molecular mechanisms of carcinogenesis plays an important role in diagnosing and treating gastric cancer. Metabolic profiling may offer the opportunity to understand the molecular mechanism of carcinogenesis and help to non-invasively identify the potential biomarkers for the early diagnosis of human gastric cancer. The aims of this study were to explore the underlying metabolic mechanisms of gastric cancer and to identify biomarkers associated with morbidity. Gas chromatography/mass spectrometry (GC/MS) was used to analyze the serum metabolites of 30 Chinese gastric cancer patients and 30 healthy controls. Diagnostic models for gastric cancer were constructed using orthogonal partial least squares discriminant analysis (OPLS-DA). Acquired metabolomic data were analyzed by the nonparametric Wilcoxon test to find serum metabolic biomarkers for gastric cancer. The OPLS-DA model showed adequate discrimination between cancer and non-cancer cohorts while the model failed to discriminate different pathological stages (I-IV) of gastric cancer patients. A total of 44 endogenous metabolites such as amino acids, organic acids, carbohydrates, fatty acids, and steroids were detected, of which 18 differential metabolites were identified with significant differences. A total of 13 variables were obtained for their greatest contribution in the discriminating OPLS-DA model [variable importance in the projection (VIP) value >1.0], among which 11 metabolites were identified using both VIP values (VIP >1) and the Wilcoxon test. These metabolites potentially revealed perturbations of glycolysis and of amino acid, fatty acid, cholesterol, and nucleotide metabolism of gastric cancer patients. These results suggest that gastric cancer serum metabolic profiling has great potential in detecting this disease and helping to understand its metabolic mechanisms. PMID:22124703

Song, Hu; Peng, Jun-Sheng; Yao, Dong-Sheng; Yang, Zu-Li; Liu, Huan-Liang; Zeng, Yi-Ke; Shi, Xian-Ping; Lu, Bi-Yan

2011-01-01

115

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

PubMed Central

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

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

2013-01-01

116

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

PubMed Central

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 the most reliable means for the extraction of pure component signals; however, a systematic manual analysis over a number of samples is both tedious and prone to error. In the past 30 years a number of computational approaches were proposed to assist in the process of the extraction of pure signals from co-eluting GC-MS components. This includes empirical methods, comparison with library spectra, eigenvalue analysis, regression and others. However, to date no approach has been recognized as best, nor accepted as standard. This situation hampers general GC-MS capabilities, and in particular has implications for the development of robust, high-throughput GC-MS analytical protocols required in metabolic profiling and biomarker discovery. Here we first discuss the nature of GC-MS data, and then review some of the approaches proposed for the extraction of pure signals from co-eluting components. We summarize and classify different approaches to this problem, and examine why so many approaches proposed in the past have failed to live up to their full promise. Finally, we give some thoughts on the future developments in this field, and suggest that the progress in general computing capabilities attained in the past two decades has opened new horizons for tackling this important problem. PMID:19818154

Liki?, Vladimir A

2009-01-01

117

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

PubMed Central

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

Bengtsson, Göran; Annadotter, Heléne

1989-01-01

118

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

PubMed

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

Guo, Liang; Lee, Hian Kee

2014-04-15

119

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

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

120

Intratracheal gas analysis for volatile substances by gas chromatography/mass spectrometry--application to forensic autopsies.  

PubMed

Intratracheal gas analysis was carried out by gas chromatography/mass spectrometry (GC/MS) in 20 burned body cases (13 males and 7 females). Volatile aromatic and aliphatic hydrocarbons were detected by GC/MS using a GS-Q column with the intratracheal gas as well as the blood in 19 cases. The characteristic patterns of mass chromatograms for gasoline, kerosene (gas oil), and liquid petroleum gas could be differentiated from each other using the intratracheal gas. The burned body in one case showed no presence of volatile substances in the intratracheal gas, nor intratracheal soot, although high concentrations (1 microg/g and more) of volatile substances were detected on the clothes. The victim also had normal CO-Hb concentrations (0.1 to 0.2%) in the heart blood. The results of intratracheal gas analysis were consistent with signs of the vital reaction. In conclusion, intratracheal gas analysis provides a supportive method for diagnosing the cause of death in burned bodies, and yields for at least 48 hours valuable information on volatile hydrocarbons (being detected in deliberate or accidental fire cases) to which the body had been exposed just before death. PMID:11210932

Takayasu, T; Ohshima, T; Kondo, T; Sato, Y

2001-01-01

121

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

E-print Network

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

Merrick, William (William F. W.)

2005-01-01

122

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

E-print Network

Aldehydes in lung cancer cell culture have been investigated using gas chromatography/mass spectrometry and solid-phase microextraction with on-fiber derivatization. In this study, the poly(dimethylsiloxane/divinylbenzene (PDMS/DVB) fiber was used...

Shan, Guangqing

2007-09-17

123

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

EPA Science Inventory

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

124

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

NASA Technical Reports Server (NTRS)

One of the primary objectives of the 1976 Viking missions was to determine whether organic compounds, possibly of biological origin, were present in the Martian surface soils. The Viking gas chromatography mass spectrometry (GCMS) instruments found no evidence for any organic compounds of Martian origin above a few parts per billion in the upper 10 cm of surface soil [l], suggesting the absence of a widely distributed Martian biota. However, Benner et d. have suggested that significant amounts of non-volatile organic compounds, possibly including oxidation products of bioorganic molecules (e.g. carboxylic acids) would not have been detected by the Viking GCMS [2]. Moreover, other key organic compounds important to biology, such as amino acids and nucleobases, would also likely have been missed by the Viking GCMS as these compounds require chemical derivatization to be stable in a GC column [3]. Recent pyrolysis experiments with a Mars soil analogue that had been innoculated with Escherichia coli bacteria have shown that amino acid decomposition products (amines) and nucleobases are among the most abundant products generated after pyrolysis of the bacterial cells [4,5]. At the part per billion level (Viking GCMS detection limit), these pyrolysis products generated from several million bacterial cells per gram of Martian soil would not have been detected by the Viking GCMS instruments [4]. Analytical protocols are under development for upcoming in situ lander opportunities to target several important biological compounds including amino acids and nucleobases. For example, extraction and chemical derivatization techniques [3] are being adapted for space flight use to transform reactive or fragile molecules that would not have been detected by the Viking GCMS instruments, into species that are sufficiently volatile to be detected by GCMS. Recent experiments carried out at NASA Goddard have shown that using this derivatization technique all of the targeted compounds mentioned above can be separated on a GC column and detected by MS at sub-picomole (< 10(exp -l2 mole) levels. With these methods, the detection limit for amino acids, carboxylic acids and nucleobases is several orders of magnitude more sensitive than the Viking GCMS instruments for these compounds. Preliminary results using this analytical technique on a variety of Martian soil analogues will be presented.

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

2004-01-01

125

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

2013-03-01

126

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

PubMed Central

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

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

2013-01-01

127

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

PubMed Central

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

2013-01-01

128

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.

David N. Blauch

129

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

130

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

2013-08-16

131

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

USGS Publications Warehouse

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

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

1981-01-01

132

Analysis of hydroxy fatty acids as pentafluorobenzyl ester, trimethylsilyl ether derivatives by electron ionization gas chromatography\\/mass spectrometry  

Microsoft Academic Search

Electron ionization (EI) gas chromatography\\/mass spectrometry (GC\\/MS) analysis of pentafluorobenzyl ester-trimethyl sllyl\\u000a ether (PFB-TMS) derivatives of hydroxy-subshtuted fatty acids provides structural information comparable to that obtained\\u000a in analysis of methyl ester-trimethyl silyl ether (Me-TMS) derivatives. Use of this derivative eliminates the need to prepare\\u000a two separate derivatives, the PFB-TMS derivative for molecular weight determination by electron capture ionization (negative\\u000a ions)

Pat Wheelan; Joseph A. Zirrolli; Robert C. Murphy

1995-01-01

133

Simultaneous determination of dimethylarsinic acid and monomethylarsonic acid after derivatization with thioglycol methylate by gas chromatography/mass spectrometry.  

PubMed

A gas chromatography/mass spectrometry (GC/MS) method has been developed to determine two methylated arsenic species in human urine samples. The yield of derivatization for dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) using thioglycol methylate (TGM) was measured. The detection limit for the derivatized DMA and MMA using the GC/MS method are 0.95 and 0.8 ng cm-3, respectively. This simple and rapid method has good precision and accuracy. Fragmentation routes of derivatized MMA and DMA are suggested on accurate mass measurements. PMID:10209873

Mester, Z; Horváth, G; Vitányi, G; Lelik, L; Fodor, P

1999-01-01

134

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

EPA Science Inventory

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

135

[Determination of levamisole residue in animal livers by two liquid-liquid extraction steps-gas chromatography-mass spectrometry].  

PubMed

A novel method wasdeveloped for the determination oflevamisole in animal livers by liquid-liquid extraction and gas chromatography-mass spectrometry. Levamisole hydrochloride was transferred to levamisole in alkalinesolution, andthen extracted intoethyl acetate. Two liquid-liquid extraction steps were carried out with HCI aqueous solution and potassium hydroxide-dichloromethane system in turn, and the liposoluble substances and the water-soluble substances were removed, respectively. The qualitative and quantitative analyses of levamisole were achieved by gas chromatography-mass spectrometry (GC-MS) system. The characteristic fragments m/z 148, 176 and 204 were selected and m/z 204 was used as the quantitative ion. A good linear relationship was obtained between the peak area and the mass concentration of levamisole from 0.25 mg/L to 3.0 mg/L with the correlation coefficient of 0.999. The limit of quantitation (LOQ) for levamisole was 5 microg/kg, which was much lower than the international maximum residue limit. The average recoveries of levamisole spiked in chicken liver, duck liver, rabbit liver and pig liver samples at three spiked levels ranged from 76% to 106% with the relative standard deviations less than 9%. The method is simple and stable without tedious sample preparation, and suitable for the determination of levamisole in animal livers. PMID:23285974

Xu, Jing; Xiao, Shanshan; Dong, Weifeng; Sui, Kai; Cao, Jijuan; Diao, Wenting; Zhang, Jing

2012-09-01

136

Simultaneous determination of non-steroidal anti-inflammatory drugs in river water by gas chromatography-mass spectrometry.  

PubMed

The gas chromatography/mass spectrometric assay method was developed for the determination of 13 non-steroidal anti-inflammatory drugs (NSAIDs) in river water. Extraction was achieved by a liquid-phase extraction procedure using methylene chloride. The extract was reacted for 30?min at 80°C based on the formation of methyl ester with 1.0?M HCl in methanol and extraction of the derivative with ethyl acetate, which was then measured by gas chromatography-mass spectrometry. The limit of quantification of NSAIDs was 1.0-60?ng/L and the calibration curve showed linearity being greater than r=0.997. The method was used to analyze ten river water samples from various regions in Korea. Diclofenac, indoprofen, ketoprofen and loxoprofen were detected at concentration of up to 1.29??g/L in river water. The developed method may prove valuable for use in the national monitoring project of NSAIDs in surface water. PMID:22282415

Shin, Ho-Sang; Oh, Jin-Aa

2012-02-01

137

Sensitive determination of fluoride in biological samples by gas chromatography-mass spectrometry after derivatization with 2-(bromomethyl)naphthalene.  

PubMed

A gas chromatography-mass spectrometric method was developed in this study in order to determine fluoride in plasma and urine after derivatization with 2-(bromomethyl)naphthalene. 2-Fluoronaphthalene was chosen as the internal standard. The derivatization of fluoride was performed in the biological sample and the best reaction conditions (10.0 mg mL(-1) of 2-(bromomethyl)naphthalene, 1.0 mg mL(-1) of 15-crown-5-ether as a phase transfer catalyst, pH of 7.0, reaction temperature of 70°C, and heating time of 70 min) were established. The organic derivative was extracted with dichloromethane and then measured by a gas chromatography-mass spectrometry. Under the established condition, the detection limits were 11 ?g L(-1) and 7 ?g L(-1) by using 0.2 mL of plasma or urine, respectively. The accuracy was in a range of 100.8-107.6%, and the precision of the assay was less than 4.3% in plasma or urine. Fluoride was detected in a concentration range of 0.12-0.53 mg L(-1) in six urine samples after intake of natural mineral water containing 0.7 mg L(-1) of fluoride. PMID:25441893

Kwon, Sun-Myung; Shin, Ho-Sang

2014-12-10

138

Unexpected dimerization of isoprene in a gas chromatography inlet. A study by gas chromatography/mass spectrometry coupling.  

PubMed

During analysis of pure isoprene by gas chromatography/mass spectrometry (GC-MS) using a programmed temperature vaporization (PTV) inlet, the presence of several isoprene dimers was detected in the total ion chromatograms (TICs). This study intends to determine the part of the instrument where dimerization occurs and the relative importance of the dimer amounts under different experimental conditions. The reference thermal dimerization of isoprene gives four six-membered cyclic dimers and two eight-membered ones. In all samples containing different amounts of freshly distilled isoprene, only peaks corresponding to the former appeared in TICs. For the same temperature, their amounts increase as the concentration of injected isoprene increases. The main products are diprene (from 80 to 100%) of the total dimers and dipentene (from 1 to 14%). The sum of the two other dimers is never higher than 6%. In conclusion, isomeric dimers are produced through a dimerization in the inlet. No dimerization of isoprene occurs in the mass spectrometer source. Then care is needed when analyzing terpenic compounds in the presence of isoprene by GC-MS because structures, retention times and mass spectra of diprene and dipentene are close. PMID:24485537

Estevez, Yannick; Gardrat, Christian; Berthelot, Karine; Grau, Etienne; De Jeso, Bernard; Ouardad, Samira; Peruch, Frédéric

2014-02-28

139

Headspace single-drop microextraction gas chromatography mass spectrometry for the analysis of volatile compounds from herba asari.  

PubMed

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

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

2013-01-01

140

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

2012-12-01

141

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

PubMed

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

López-Guarnido, Olga; Tabernero, María Jesús; Hernández, Antonio F; Rodrigo, Lourdes; Bermejo, Ana M

2014-10-01

142

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

143

Elucidation of n-butyl benzyl phthalate biodegradation using high-performance liquid chromatography and gas chromatography-mass spectrometry.  

PubMed

n-Butyl benzyl phthalate (BBP) is an endocrine-disrupting chemical. A bacterium species capable of using BBP as the sole source of carbon and energy was isolated from mangrove sediment. Effects of BBP concentration, pH, temperature, and salinity on BBP biodegradation were studied. The optimum pH, temperature, and salinity for the BBP biodegradation were 7.0, 37 degrees C, and 15 g L(-1), respectively. BBP was completely degraded within 6 days under optimum conditions, and the biodegradation of BBP could be fitted to a first-order kinetic model. The major metabolites of BBP biodegradation were identified as mono-butyl phthalate, mono-benzyl phthalate, phthalic acid, and benzoic acid by using high-performance liquid chromatography and gas chromatography-mass spectrometry. A preliminary metabolic pathway was proposed for the biodegradation of BBP. PMID:16871373

Xu, Xiang-Rong; Li, Hua-Bin; Gu, Ji-Dong

2006-09-01

144

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

PubMed Central

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

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

2013-01-01

145

Gas chromatography/mass spectrometric assay of endogenous cellular lipid peroxidation products: quantitative analysis of 9- and 10-hydroxystearic acids.  

PubMed

A sensitive, specific, accurate and reproducible gas chromatography/mass spectrometry method was developed for the assay of 9- and 10-hydroxystearic acids in samples obtained as cell extracts. The preparation of the samples required specific procedures to allow the analysis of both the free and the conjugated hydroxy acids as the corresponding methyl esters. The quantification used propyl-paraben as the internal standard and monitoring of a specific fragment of each isomeric hydroxy acid methyl ester, and allowed quantification of the conjugate and the free fractions of both 9- and 10-hydroxystearic acids. This method is suitable for identification and quantification (LOQ 1.8 and 4.4 ng, respectively) of these important metabolites of lipid peroxidation. In particular the development of an assay for the free 9-hydroxystearic acid methyl ester makes the method a reliable analytical tool for investigations of the role of this metabolite in the mechanisms of tumour cell proliferation. PMID:11948817

Bertucci, C; Hudaib, M; Boga, C; Calonghi, N; Cappadone, C; Masotti, L

2002-01-01

146

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

PubMed

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

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

2014-12-01

147

Rapid identification of pork for halal authentication using the electronic nose and gas chromatography mass spectrometer with headspace analyzer.  

PubMed

The volatile compounds of pork, other meats and meat products were studied using an electronic nose and gas chromatography mass spectrometer with headspace analyzer (GCMS-HS) for halal verification. The zNose™ was successfully employed for identification and differentiation of pork and pork sausages from beef, mutton and chicken meats and sausages which were achieved using a visual odor pattern called VaporPrint™, derived from the frequency of the surface acoustic wave (SAW) detector of the electronic nose. GCMS-HS was employed to separate and analyze the headspace gasses from samples into peaks corresponding to individual compounds for the purpose of identification. Principal component analysis (PCA) was applied for data interpretation. Analysis by PCA was able to cluster and discriminate pork from other types of meats and sausages. It was shown that PCA could provide a good separation of the samples with 67% of the total variance accounted by PC1. PMID:21420795

Nurjuliana, M; Che Man, Y B; Mat Hashim, D; Mohamed, A K S

2011-08-01

148

Headspace solid-phase microextraction for characterization of fragrances of lemon verbena (Aloysia triphylla) by gas chromatography-mass spectrometry.  

PubMed

Natural fragrances from lemon verbena (Aloysia triphylla) were studied by headspace solid phase microextraction (HS-SPME) techniques followed by gas chromatography-mass spectrometry (GC-MS), with six different fibre coatings being tested to evaluate the extraction efficiencies of several selected compounds. A total of 14 compounds were identified in the fragrances of lemon verbena. Geranial and neral were detected as major components and alpha-pinene, beta-pinene, beta-caryophyllene, and curcumene as minor components. Enantiomeric analysis of chiral compounds from lemon verbena was carried out on a chiral column. alpha-Pinene, limonene, and camphor in the fragrances emitted from lemon verbena were found in the (+), (-), and (-) forms, respectively. PMID:15335064

Kim, Nam-Sun; Lee, Dong-Sun

2004-01-01

149

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

PubMed

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

Rajiv, P; Rajeshwari, Sivaraj; Venckatesh, Rajendran

2013-12-01

150

Determination of linear alkylbenzenes in fish tissue by gel permeation chromatography and gas chromatography-mass spectrometry.  

PubMed

A gel permeation chromatographic (GPC) procedure is described for separation of the long-chain linear alkylbenzenes (LABs) from fish muscle tissues. This technique was found to remove the matrix interference significantly and thereby improve the sensitivity of detection of LABs in the extracts. Gas chromatography-mass spectrometry (GC-MS) was then used to quantitate LABs in different species of fish and also fish from different locations on a transect from the outfalls from the Orange County Sanitation Districts, in the coastal waters of Southern California. The results are consistent with the proximity of the (sewage) source. The data, thus, show that LAB contents in fish tissues, especially that from white croaker (Genyonemus lineatus) are useful in assessing exposure to sewage residues in the marine waters. This method of concentrating LABs by GPC could be applicable to all other similar biological matrices. PMID:11822387

Venkatesa, M Indira; Northrup, Terrence; Phillip, Charles R

2002-01-01

151

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

2009-05-01

152

Ink dating using thermal desorption and gas chromatography/mass spectrometry: comparison of results obtained in two laboratories.  

PubMed

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

Koenig, Agnès; Bügler, Jürgen; Kirsch, Dieter; Köhler, Fritz; Weyermann, Céline

2015-01-01

153

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

PubMed

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

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

2014-10-01

154

A low thermal mass fast gas chromatograph and its implementation in fast gas chromatography mass spectrometry with supersonic molecular beams.  

PubMed

A new type of low thermal mass (LTM) fast gas chromatograph (GC) was designed and operated in combination with gas chromatography mass spectrometry (GC-MS) with supersonic molecular beams (SMB), including GC-MS-MS with SMB, thereby providing a novel combination with unique capabilities. The LTM fast GC is based on a short capillary column inserted inside a stainless steel tube that is resistively heated. It is located and mounted outside the standard GC oven on its available top detector port, while the capillary column is connected as usual to the standard GC injector and supersonic molecular beam interface transfer line. This new type of fast GC-MS with SMB enables less than 1 min full range temperature programming and cooling down analysis cycle time. The operation of the fast GC-MS with SMB was explored and 1 min full analysis cycle time of a mixture of 16 hydrocarbons in the C(10)H(22) up to C(44)H(90) range was achieved. The use of 35 mL/min high column flow rate enabled the elution of C(44)H(90) in less than 45 s while the SMB interface enabled splitless acceptance of this high flow rate and the provision of dominant molecular ions. A novel compound 9-benzylazidanthracene was analyzed for its purity and a synthetic chemistry process was monitored for the optimization of the chemical reaction yield. Biodiesel was analyzed in jet fuel (by both GC-MS and GC-MS-MS) in under 1 min as 5 ppm fatty acid methyl esters. Authentic iprodion and cypermethrin pesticides were analyzed in grapes extract in both full scan mode and fast GC-MS-MS mode in under 1 min cycle time and explosive mixture including TATP, TNT and RDX was analyzed in under 1 min combined with exhibiting dominant molecular ion for TATP. Fast GC-MS with SMB is based on trading GC separation for speed of analysis while enhancing the separation power of the MS via the enhancement of the molecular ion in the electron ionization of cold molecules in the SMB. This paper further discusses several features of fast GC and fast GC-MS and the various trade-offs involved in having powerful and practical fast GC-MS. PMID:22119674

Fialkov, Alexander B; Moragn, Mati; Amirav, Aviv

2011-12-30

155

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

156

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

157

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

158

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

159

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

EPA Science Inventory

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

160

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

PubMed

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

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

2013-08-01

161

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

PubMed

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

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

2014-01-15

162

[Determination of benzene series in marine sediment by headspace solid phase microextraction-gas chromatography-mass spectrometry].  

PubMed

A method was developed for the determination of benzene series (BTEX) in marine sediment by headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). The conditions for extraction and gas chromatography, such as the amount of salt added, equilibrium time, extraction temperature, extraction time, desorption time and injection temperature, were optimized. The analytes were quantitatively analyzed by the internal standard method. The results showed that the linear correlation coefficients of BTEX compounds were from 0.995 to 0.999 in the range of 0.500-20.0 ng/g. The detection limits of this method were from 0.081 8 to 0. 175 ng/g, with the RSDs of inter- and intra-day of 1.2%-3.6% (n = 5) and 0.4%-6.3% (n = 3). The average recoveries under two different spiked concentrations (2.0 and 15.0 ng) were 61.7%-79.5% and 77.1%-85.6% with RSDs of 5.4%-9.6% and 3.9%-7.6% (n = 5), respectively. This method is quick, sensitive, simple, accurate and reproducible. It can be used to analyze the marine sediment samples with trace BTEX. PMID:24669715

Wu, Jinhao; Wang, Zhaohui; Wang, Bai; Zhou, Zunchun; Wang, Nianbin

2013-12-01

163

Accuracy profile validation of a new analytical method for propane measurement using headspace-gas chromatography-mass spectrometry.  

PubMed

Propane can be responsible for several types of lethal intoxication and explosions. Quantifying it would be very helpful to determine in some cases the cause of death. Some gas chromatography-mass spectrometry (GC-MS) methods of propane measurements do already exist. The main drawback of these GC-MS methods described in the literature is the absence of a specific propane internal standard necessary for accurate quantitative analysis. The main outcome of the following study was to provide an innovative Headspace-GC-MS method (HS-GC-MS) applicable to the routine determination of propane concentration in forensic toxicology laboratories. To date, no stable isotope of propane is commercially available. The development of an in situ generation of standards is thus presented. An internal-labeled standard gas (C?DH?) is generated in situ by the stoichiometric formation of propane by the reaction of deuterated water (D?O) with Grignard reagent propylmagnesium chloride (C?H?MgCl). The method aims to use this internal standard to quantify propane concentrations and, therefore, to obtain precise measurements. Consequently, a complete validation with an accuracy profile according to two different guidelines, the French Society of Pharmaceutical Sciences and Techniques (SFSTP) and the Gesellschaft für toxikologische und Forensische Chemie (GTFCh), is presented. PMID:24327620

Smith, Fiona; Augsburger, Marc; Varlet, Vincent

2014-03-01

164

Gas-liquid chromatography-mass spectrometry of hydroxylated octadecanols derived from hydroxylated stearic acids  

Microsoft Academic Search

A gas-liquid chromatographic-mass spectro- metric method of determining the position of oxygen atoms on polyfunctional fatty acids has been explored. The method con- sists of reduction of keto, hydroperoxy, epoxy, and carboxylic acid groups with LiAIH4 to the corresponding alcohols; tri- methylsilylation with bis(trimethylsily1) acetamide; and analysis by means of the combined gas-liquid chromatograph-mass spectrometer.

WALTER J. ESSELMAN

165

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

PubMed

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

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

2014-05-01

166

A gas chromatography–mass spectrometric method to determine skin-whitening agents in cosmetic products  

Microsoft Academic Search

An analytical method is proposed here to determine three allowed (kojic acid, azelaic acid and arbutin) and two forbidden (resorcinol and hydroquinone) skin-whitening agents in cosmetics. The method is based on gas chromatography coupled with mass spectrometric detection, which allows the two prohibited target compounds to be identified unequivocally by means of their mass spectra acquired in full-scan mode at

Alberto Chisvert; Judit Sisternes; Ángel Balaguer; Amparo Salvador

2010-01-01

167

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...

168

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

169

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

Microsoft Academic Search

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

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

2004-01-01

170

Stable isotope dilution gas chromatography-mass spectrometry for quantification of thymoquinone in black cumin seed oil.  

PubMed

Black cumin seed (Nigella sativa L.) is a widely used spice and herb, where thymoquinone (2-isopropyl-5-methyl-1,4-benzoquinone) is the major bioactive compound. Here, a stable isotope dilution (SID) gas chromatography-mass spectrometry (GC-MS) technique was developed for the quantification of thymoquinone. A doubly deuterated thymoquinone ([(2)H2]-thymoquinone) was synthesized for the first time with more than 93% deuteration degree shown by mass spectrometry and proton nuclear magnetic resonance ((1)H NMR). This compound was used as an internal standard for the quantification of thymoquinone using a SID GC-MS method. The validation experiment showed a recovery rate of 99.1 ± 1.1% relative standard deviation (RSD). Standard addition and external calibration methods have also been used to quantify thymoquinone, which cross-validated the developed stable isotope dilution assay (SIDA). In comparison to external calibration and standard addition methods, the SIDA method is robust and accurate. The concentration of thymoquinone in five marketed black cumin seed oils ranged between 3.34 and 10.8 mg/mL by use of SID GC-MS. PMID:24871868

Johnson-Ajinwo, Okiemute Rosa; Li, Wen-Wu

2014-06-18

171

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

PubMed

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

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

2013-11-15

172

Monitoring human exposure to ethylene oxide by the determination of hemoglobin adducts using gas chromatography-mass spectrometry  

SciTech Connect

Globin samples from ethylene oxide-exposed workers and non-exposed referrents were analyzed by two methods: (i) gas chromatography-mass spectrometry determination of Nt-(2-hydroxyethyl)histidine as its methyl ester heptafluorobutyryl derivative, after hydrolysis of the protein and isolation of the alkylated amino acid by ion exchange chromatography. The internal standard, Nt-(2-hydroxy-d4-ethyl)histidine, was added to the protein before hydrolysis. (ii) Determination of N-(2-hydroxyethyl)valine after derivatization of the protein by a modified Edman procedure, extraction and g.c.-m.s. determination of alkylated N-terminal valine in the form of its pentafluorophenylthiohydantoin derivative. The internal standard used was in this case a globin with a known content of hydroxy-d4-ethylated amino acids. The two methods gave consistent results, especially at high levels of alkylated products. The average content of hydroxyethylhistidine was 0.6 nmol/g higher than the content of hydroxyethylvaline. Higher levels of background alkylation (of unknown origin) were recorded with the histidine method as compared with the valine method, suggesting that the latter assay should show greater sensitivity for low level ethylene oxide exposure monitoring.

Farmer, P.B.; Bailey, E.; Gorf, S.M.; Toernqvist, M.O.; Osterman-Golkar, S.; Kautiainen, A.; Lewis-Enright, D.P.

1986-04-01

173

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

174

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

PubMed Central

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

Saxena, Prem Narain

2013-01-01

175

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. PMID:24151524

2013-01-01

176

New pilot for validation of automated analyses of organics by gas chromatography mass spectrometry (GCMS): application to space researches  

NASA Astrophysics Data System (ADS)

The search for complex organic molecules in extraterrestrial environments, including important biomolecules such as amino acids and carboxylic acids, will require after an extraction a derivatization step to transform these organic compounds into species that are sufficiently volatile to be detected by gas chromatography mass spectrometry (GCMS). Current and future space missions, such as Mars Science Laboratory (MSL 2011, will include such derivatization method and thus a dedicated laboratory pilot is needed to validate protocols before launch of the probes. A new in situ generic Derivatization-Pyrolysis Unit (DPU) is presented. Derivatization is carried out in a 4 mL reactor placed on a GCMS injector for automated derivatization as well as for pre- and post treatment of the sample. The DPU unit is evaluated in terms of its technical features. The performances are illustrated with applications including conventional and in situ derivatization for using terrestrial Mars analog materials enriched by a 5 nmol amino acids solution. The DPU allows the analysis of a wide range of molecules to be detected and can be adapted to samples from any solid spatial object such as Mars, asteroids and comets. This pilot is a good basis for the validation of future generations of instruments, such as the Mars Organic Molecule Analyzer (MOMA) of the Exomars 2018 mission, dedicated to the search for organics in spatial environments.

Sternberg, Robert; Buch, Arnaud; Chazalnoel, Pascale; Geffroy, Claude; David, Marc

177

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

PubMed

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

España Amórtegui, Julio César; Guerrero Dallos, Jairo Arturo

2015-09-01

178

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

PubMed

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

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

2015-02-01

179

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

PubMed

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

Tang, Maochun; Hu, Gouyong; Zhao, Yan; Su, Mingming; Wang, Yuhui; Jia, Wei; Qiu, Yunping; Liu, George; Wang, Xingpeng

2013-05-01

180

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

PubMed

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

Ghasemi, Ensieh

2012-08-17

181

[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

182

[Determination of bisphenol A from toys and food contact materials by derivatization and gas chromatography-mass spectrometry].  

PubMed

A method was developed for the determination of bisphenol A (BPA) in toys and food contact materials. The BPA was extracted with Soxhlet extraction method from the sample and reacted with acetic anhydride. The final product was determined by gas chromatography-mass spectrometry (GC-MS). To achieve the optimum derivatization performance, the derivatization time and dosage of derivatization reagent etc. were investigated. Under the optimized experimental conditions, the final product was stable and the peak shape was good. The linearity of the derivative was good in the range of 0.05 to 50 mg/L with the correlation coefficient (r2) above 0.999. The recoveries ranged from 80% to 93% at the spiked levels of 0.05, 1.00, 10.00 mg/kg with the relative standard deviations (RSDs) less than 3.7%. The limit of detection (S/N = 3) was 10 microg/kg. The method is accurate and has high recovery. The method is suitable for the inspection of bisphenol A in toys and food contact materials. PMID:23383489

Gao, Yonggang; Zhang, Yanyan; Gao, Jianguo; Zhang, Huiling; Zheng, Lisha; Chen, Jing

2012-10-01

183

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

PubMed

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

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

2014-02-27

184

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

185

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 0.01 mg/kg for the individual GE (corresponding to 0.002-0.003 mg/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

2013-10-25

186

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

PubMed

Chinese mitten crab (Eriocheir sinensis) from Yangcheng Lake in Jiangsu Province is a popular species due to its unique pleasant aroma and intensive umami taste. In this study, odorants in steamed male E. sinensis were investigated using the headspace-monolithic material sorptive extraction technique coupled with gas chromatography-mass spectrometry-olfactometry (GC-MS-O). A total of 74 volatile compounds were found, and the results of the GC-MS-O analysis, combined with odor activity values, showed that trimethylamine (fishy, ammonia-like odor), (Z)-4-heptenal (mushroom-like odor), and benzaldehyde (paint-like odor) were the important odorants (IOs) in all 4 of the edible parts of steamed male E. sinensis. Furthermore, heptanal (mushroom-like odor) was common to the abdomen, claw, and leg meat but was not found as the IO in the gonad. The abdomen meat also contained 3-methylbutanal (vegetable-like, grassy odor), while 2 additional IOs were found in claw meat (2-methylbutanal, which has a mushroom odor and 3-ethyl-2,5-dimethylpyrazine, which has a chocolate-like, musty odor). Another IO (2-nonanone, chocolate-like odor) was also found in leg meat, while (E)-2-nonenal (green, fruity odor) was the IO found exclusively in the gonad. PMID:24962135

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

2014-07-01

187

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

PubMed

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

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

2015-05-01

188

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

PubMed

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

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

2012-10-01

189

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

PubMed

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

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

2010-10-01

190

Plasma Metabolite Profiling and Chemometric Analyses of Lung Cancer along with Three Controls through Gas Chromatography-Mass Spectrometry  

PubMed Central

Lung cancer has been the most common death causing cancer in the world for several decades. This study is focused on the metabolite profiling of plasma from lung cancer (LC) patients with three control groups including healthy non-smoker (NS), smokers (S) and chronic obstructive pulmonary disease patients (COPD) samples using gas chromatography-mass spectrometry (GC-MS) in order to identify the comparative and distinguishing metabolite pattern for lung cancer. Metabolites obtained were identified through National Institute of Standards and Technology (NIST) mass spectral (Wiley registry) and Fiehn Retention Time Lock (RTL) libraries. Mass Profiler Professional (MPP) Software was used for the alignment and for all the statistical analysis. 32 out of 1,877 aligned metabolites were significantly distinguished among three controls and lung cancer using p-value ? 0.001. Partial Least Square Discriminant Analysis (PLSDA) model was generated using statistically significant metabolites which on external validation provide high sensitivity (100%) and specificity (78.6%). Elevated level of fatty acids, glucose and acids were observed in lung cancer in comparison with control groups apparently due to enhanced glycolysis, gluconeogenesis, lipogenesis and acidosis, indicating the metabolic signature for lung cancer. PMID:25712604

Musharraf, Syed Ghulam; Mazhar, Shumaila; Choudhary, Muhammad Iqbal; Rizi, Nadeem; Atta-ur-Rahman

2015-01-01

191

Gas chromatography-mass spectrometry analysis of different organic crude extracts from the local medicinal plant of Thymus vulgaris L  

PubMed Central

Objective To isolate and analyze the chemical composition in different crude extracts of from the leaves of locally grown of Thymus vulgaris L (T. vulgaris) by gas chromatography-mass spectrometry (GC-MS). Methods The shade dried leaves powder was extracted with methanol by using Soxhlet extractor. Methanol crude extracts of T. vulgaris and the derived fractions of hexane, chloroform, ethyl acetate and butanol were obtained. Results Qualitative analyses of various organic crude extracts of T. vulgaris by using GC-MS showed that there were different types of high and low molecular weight compounds. Most of the isolated and identified compounds by GC-MS in the crude extracts are basically biologically important. Further, the T. vulgaris leaf possessed certain characteristics that can be ascribed to cultivation on a domestic plantation. The crude extracts were prepared from the powder leaves of T. vulgaris for respective compounds can be chosen on the basis of above GC-MS analysis. Conclusions All the major compounds were identified and characterized by spectroscopic method in different organic crude extracts of T. vulgaris are biologically active molecules. Thus the identification of a good number of compounds in various crude extracts of T. vulgaris might have some ecological role. PMID:23570020

Hashmi, Laila Salim Al; Hossain, Mohammad Amzad; Weli, Afaf Mohammed; Al-Riyami, Qasim; Al-Sabahi, Jamal Nasser

2013-01-01

192

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

PubMed

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

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

2015-01-01

193

Plasma Metabolite Profiling and Chemometric Analyses of Lung Cancer along with Three Controls through Gas Chromatography-Mass Spectrometry.  

PubMed

Lung cancer has been the most common death causing cancer in the world for several decades. This study is focused on the metabolite profiling of plasma from lung cancer (LC) patients with three control groups including healthy non-smoker (NS), smokers (S) and chronic obstructive pulmonary disease patients (COPD) samples using gas chromatography-mass spectrometry (GC-MS) in order to identify the comparative and distinguishing metabolite pattern for lung cancer. Metabolites obtained were identified through National Institute of Standards and Technology (NIST) mass spectral (Wiley registry) and Fiehn Retention Time Lock (RTL) libraries. Mass Profiler Professional (MPP) Software was used for the alignment and for all the statistical analysis. 32 out of 1,877 aligned metabolites were significantly distinguished among three controls and lung cancer using p-value ? 0.001. Partial Least Square Discriminant Analysis (PLSDA) model was generated using statistically significant metabolites which on external validation provide high sensitivity (100%) and specificity (78.6%). Elevated level of fatty acids, glucose and acids were observed in lung cancer in comparison with control groups apparently due to enhanced glycolysis, gluconeogenesis, lipogenesis and acidosis, indicating the metabolic signature for lung cancer. PMID:25712604

Musharraf, Syed Ghulam; Mazhar, Shumaila; Choudhary, Muhammad Iqbal; Rizi, Nadeem; Atta-Ur-Rahman

2015-01-01

194

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

PubMed

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

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

2004-12-01

195

Determination of Volatile Compounds in Four Commercial Samples of Japanese Green Algae Using Solid Phase Microextraction Gas Chromatography Mass Spectrometry  

PubMed Central

Green algae are of great economic importance. Seaweed is consumed fresh or as seasoning in Japan. The commercial value is determined by quality, color, and flavor and is also strongly influenced by the production area. Our research, based on solid phase microextraction gas chromatography mass spectrometry (SPME-GC-MS), has revealed that volatile compounds differ intensely in the four varieties of commercial green algae. Accordingly, 41 major volatile compounds were identified. Heptadecene was the most abundant compound from Okayama (Ulva prolifera), Tokushima (Ulva prolifera), and Ehime prefecture (Ulva linza). Apocarotenoids, such as ionones, and their derivatives were prominent volatiles in algae from Okayama (Ulva prolifera) and Tokushima prefecture (Ulva prolifera). Volatile, short chained apocarotenoids are among the most potent flavor components and contribute to the flavor of fresh, processed algae, and algae-based products. Benzaldehyde was predominant in seaweed from Shizuoka prefecture (Monostroma nitidum). Multivariant statistical analysis (PCA) enabled simple discrimination of the samples based on their volatile profiles. This work shows the potential of SPME-GC-MS coupled with multivariant analysis to discriminate between samples of different geographical and botanical origins and form the basis for development of authentication methods of green algae products, including seasonings. PMID:24592162

Yoshikawa, Keisuke; Fujita, Akira; Mase, Nobuyuki; Watanabe, Naoharu

2014-01-01

196

Characterisation and discrimination of various types of lac resin using gas chromatography mass spectrometry techniques with quaternary ammonium reagents.  

PubMed

A variety of lac resin samples obtained from artists' suppliers, industrial manufacturers, and museum collections were analysed using gas chromatography mass spectrometry (GCMS) and reactive pyrolysis GCMS with quaternary ammonium reagents. These techniques allowed a detailed chemical characterisation of microgram-sized samples, based on the detection and identification of derivatives of the hydroxy aliphatic and cyclic (sesquiterpene) acids that compose the resin. Differences in composition could be related to the nature of the resin, e.g. wax-containing (unrefined), bleached, or aged samples. Furthermore, differences in the relative abundances of aliphatic hydroxyacids appear to be associated with the biological source of the resin. The diagnostic value of newly characterised lac components, including 8-hydroxyacids, is discussed here for the first time. Identification of derivatised components was aided by AMDIS deconvolution software, and discrimination of samples was enhanced by statistical evaluation of data using principal component analysis. The robustness of the analyses, together with the minimal sample size required, make these very powerful approaches for the characterisation of lac resin in museum objects. The value of such analyses for enhancing the understanding of museum collections is illustrated by two case studies of objects in the collection of the Philadelphia Museum of Art: a restorer's varnish on a painting by Luca Signorelli, and a pictorial inlay in an early nineteenth-century High Chest by George Dyer. PMID:24642395

Sutherland, K; del Río, J C

2014-04-18

197

Direct detection of Mycobacterium tuberculosis in sputum using combined solid phase extraction-gas chromatography-mass spectrometry.  

PubMed

Recently, thermally-assisted hydrolysis and methylation followed by gas chromatography-mass spectrometry (THM-GC-MS) in combination with chemometrics has been used to develop a 20-compound model for fast differentiation of Mycobacterium tuberculosis (MTB) from Non-tuberculous mycobacteria (NTM) in bacterial cultures. This model provided better than 95% accuracy. In our current work a hexane/methanol/water extraction followed by a solid phase extraction (SPE) clean-up procedure was developed for use before THM-GC-MS, to make the test suitable for the identification of mycobacteria in sputum. The 20 biomarker model had to be adapted since many compounds were also found in the sputum of non-tuberculosis patients. An algorithm was established based on tuberculostearic acid, hexacosanoic acid and mycoserosates. The detection limit of the method was approximately 1×10(4) bacteria/mL sputum. Sputum specimens from 32 patients from South Africa who were suspected of having tuberculosis were blindly tested using the new method. Eight of the nine culture-positive sputum specimens were detected by the new SPE-THM-GC-MS method, resulting in a sensitivity of 89%. The specimen that was missed by the new method was also microscopy negative. The specificity of the test was 100%; all 23 microscopy- and culture-negative specimens were correctly identified as negative by SPE-THM-GC-MS. PMID:25728368

Dang, Ngoc A; Mourão, Marta; Kuijper, Sjoukje; Walters, Elisabetta; Janssen, Hans-Gerd; Kolk, Arend H J

2015-04-01

198

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

199

[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

200

High-throughput metabolic flux analysis based on gas chromatography-mass spectrometry derived 13C constraints.  

PubMed

13C-constrained flux balancing analysis based on gas chromatography-mass spectrometry data is presented here as a simple and robust method for the estimation of intracellular carbon fluxes. In this approach, the underdetermined system of metabolite balances deduced from stoichiometric relations and measured extracellular rates is complemented with 13C constraints from metabolic flux ratio analysis. Fluxes in central carbon metabolism of exponentially growing Escherichia coli were estimated by 13C-constrained flux balancing from three different 13C-labeled glucose experiments. The best resolution of the network was achieved using 13C constraints derived from [U-13C]glucose and [1-13C]glucose experiments. The corresponding flux estimate was in excellent agreement with a solution that was independently obtained with a comprehensive isotopomer model. This new methodology was also demonstrated to faithfully capture the intracellular flux distribution in E. coli shake flasks and 1-ml deep-well microtiter plates. Due to its simplicity, speed, and robustness, 13C-constrained metabolic flux balancing is promising for routine and high-throughput analysis on a miniaturized scale. PMID:14751266

Fischer, Eliane; Zamboni, Nicola; Sauer, Uwe

2004-02-15

201

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

PubMed

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

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

2014-10-24

202

[Simultaneous determination of nine pharmaceuticals personal care products in waters by solid phase extraction-gas chromatography-mass spectrometry].  

PubMed

An analytical method has been developed and validated for the simultaneous determination of nine pharmaceuticals and personal care products (PPCPs) in water samples, including salicylic acid, naproxen, ibuprofen, paracetamol, clofibric acid, triclosan, diclofenac, ketoprofen, bisphenol A. The qualification and quantification of the target compounds were performed by gas chromatography-mass spectrometry in selected ion monitoring mode (GC-MS-SIM). The water samples were concentrated and purified through Oasis HLB cartridges after the pH value of the water was adjusted to 3, then derivatized with trimethyl sulfonium hydroxide (TMSH) at room temperature, and determined by GC-MS-SIM using 2,4,5-fenoprop as internal standard. The conditions for sample pretreatment (e. g. solid phase extraction and derivatization) were studied. Under the optimized conditions, the recoveries were ranged from 50.7% to 115.4% with the relative standard deviations lower than 10%. The limits of detection were in the range of 0.03-0.30 microg/L and the limits of quantification were in the range of 0.15-1.50 microg/L. The method has been successfully applied to monitor the occurrence of the PPCPs residues in agricultural irrigation water in Dongguan, Guangdong Province. The four compounds were detected at maximum mass concentration range of 0.176-0.998 microg/L. It proved that this analytical method is sensitive, reliable and acceptable. PMID:24984466

Jia, Yanyan; Tan, Jianhua; Xu, Chen; Tang, Jiajun; Wang, Yingli; Xie, Qilai

2014-03-01

203

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

2010-04-01

204

Identifying acetylated lignin units in non-wood fibers using pyrolysis-gas chromatography/mass spectrometry.  

PubMed

A series of non-wood plant fibers, namely kenaf, jute, sisal and abaca, have been analyzed upon pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) of the whole material. The pyrolysis products mainly arise from the carbohydrate and lignin moieties of the fibers. The lignin-derived phenols belonged to the p-hydroxyphenylpropanoid (H), guaiacylpropanoid (G) and syringylpropanoid (S) structures, and showed a high S/G ratio of between 2.0 and 5.4, the highest corresponding to kenaf. Among the lignin-derived phenols released, small amounts of sinapyl and coniferyl acetates (in both cis- and trans-forms) were identified for the first time upon Py-GC/MS of lignocellulosic materials. Acetylation of the sinapyl and coniferyl alcohols was at the gamma-position of the side chain. The release of these alcohols derived from intact acetylated lignin units upon pyrolysis seems to indicate that the native lignin in the fibers selected for this study is at least partially acetylated. Sinapyl (and coniferyl) acetates have recently been suggested to be authentic lignin precursors involved in the polymerization of lignin along with the normal sinapyl and coniferyl alcohols. Py-GC/MS will offer a convenient and rapid tool for analyzing naturally acetylated lignins, as well as to screen plant materials for the presence of acetylated units in lignin. PMID:15164346

del Río, José C; Gutiérrez, Ana; Martínez, Angel T

2004-01-01

205

Determination of Dioxin by Solid Phase Microextraction Coupled with Gas Chromatography\\/Mass Spectrometry  

Microsoft Academic Search

Objective :A sensitive and accurate method has been developed for the determination of Dioxin by solid phase microextraction(SPME)coupled with gas chromatography and mass spectrometric detection(GC-MS). Method: Some factors influencing solid-phase microexaction(SPME) extraction efficiency such as extraction of time and temperature were studied. The result shows: with the extraction of time 30 min, temperature 45degC, Detection limit of the method is

Liu YanQun; TanYou Ming; Zhou Yi Kai

2008-01-01

206

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

207

Capillary gas chromatography-mass spectrometry of resin acids in tall oil rosin  

Microsoft Academic Search

The resin acid composition of Finnish tall oil rosin was investigated by gas chromatography and mass spectrometry employing\\u000a open tubular capillary columns. On a column coated with 1,4-butanediol succinate, 16 resin acids found in tall oil rosin samples\\u000a were well resolved, and mass spectra could be recorded. All resin acids were confirmed to be of the pimaric and abietic types

B. Holmbom; E. Avela; S. Pekkala

1974-01-01

208

Simultaneous determination of Sonchus arvensis L. triterpenes by gas chromatography-mass spectrometry  

Microsoft Academic Search

Sonchus arvensis L. or sow thistle has proved an excellent source of pentacylic triterpenes; triterpenes account for about 6% of the crude\\u000a lipid extract or 0.2% of the dried plant. Composition of the triterpenoid fraction, as indicated by gas chromatography of\\u000a the corresponding acetates, was ?-amyrin (9%), ?-amyrin (21%), lupeol (13%), taraxasterol (24%) and pseudo-taraxasterol (12%).\\u000a A single, long-chain alcohol

S. N. Hooper; R. F. Chandler; E. Lewis; W. D. Jamieson

1982-01-01

209

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, 20 min extraction). Extraction dependence on matrix was discussed using model wines with different ethanol contents (8%, 12%, and 18%) as well as water and different wines (dry white, dry red and sweet liqueur), with the lowest sensitivities obtained for highest ethanol contents in model wine and for liqueur wine. Limits of detection for GC×GC-ToF-MS method were 0.09-2.92 ng/L depending on the examined compound and matrix (compared to 0.1-13.3 ng/L obtained using GC/MS(SIM)). For GC-MS/MS method lower detection limits were achieved than for the GC×GC method (0.01-0.1 ng/L), however comprehensive gas chromatography-mass spectrometry provides full spectral information on analyzed compounds. Both methods had limits of detection far below odor thresholds of haloanisoles in wine, good linearity up to 2000 ng/L tested and good precision, what makes them suitable for analysis of these compounds in low ppt levels. PMID:23932370

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

2013-10-25

210

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

PubMed

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

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

2014-09-01

211

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

212

Analysis of anisoles in wines using pervaporation coupled to gas chromatography-mass spectrometry.  

PubMed

Two procedures for the determination of 2,4,6-trichloroanisole, 2,6-dichloroanisole and 2,4,6-tribromoanisole in tainted wines have been developed. Both methods are based on pervaporation (PV) of the analytes and final determination by gas chromatography-ion-trap tandem mass spectrometry (GC-MS). In the Approach A, pervaporation was directly coupled to the GC-MS system (PV-GC-MS/MS) and in Approach B a solid-phase cryogenic trap-thermal desorption (CT-TD) device was connected to the pervaporator (PV-CT-TD-GC-MS/MS). Results show that last coupling present better sensitivity as well as precision. Detection limits (DLs) for 2,4,6-trichloroanisole were estimated to be 25.8 and 4.2 ng l(-1) for Approaches A and B, respectively, when 10 ml of sample was analysed. Linear range of the calibration curves ranged from quantification limit to 15 ng for PV-GC-MS/MS and from quantification limit to 2 ng for PV-CT-TD-GC-MS/MS. Due to the low threshold odour concentration of these compounds in wine, Approach B is proposed as a reliable method for analytical quality control of this product. PMID:15499927

Gómez-Ariza, J L; García-Barrera, T; Lorenzo, F

2004-09-17

213

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

214

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

SciTech Connect

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

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

2012-05-17

215

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

PubMed

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

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

2013-07-01

216

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

PubMed

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

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

2014-07-01

217

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

218

Gas chromatography-mass spectrometry characterisation of the anti-Listeria components of Garcinia kola seeds.  

PubMed

Adsorption chromatography was used to separate the bioactive constituents of the crude n-hexane extract of Garcinia kola seeds. The silica gel 60 column fractions were eluted using the solvent combination of benzene: ethanol : ammonium hydroxide (BEA) in the ratio combination of 36 : 4 : 0.4 v/v. The fractions were tested for anti-Listeria activities by determining their MIC50, MIC90 or MIC against 4 Listeria isolates. The fractions were labelled BEA1 to BEA5 and 3 out of the 5 fractions eluted were active against the test Listeria species with MIC's ranging from MIC 0.57 mg/mL to MIC50 0.625 mg/mL. The most active fractions, BEA2 and BEA3, were subjected to gas chromatography coupled to mass spectrometry (GC-MS) to identify their composition. Fraction BEA2 constituted of 18 compounds mostly sterols and the BEA3 fraction contained 27 compounds with the most abundant compounds being fatty acids derivatives. The BEA2 fraction's interactions with antibiotics proved to be 100% synergistic with ciprofloxacin and ampicillin whilst it exhibited 50% additivity and 50% synergism with penicillin G. However, all the interactions of the BEA2 fraction with each of the conventional antibiotics used were synergistic against the human listeriosis causative bacteria Listeria monocytogenes. PMID:25757343

Penduka, D; Basson, K A; Mayekiso, B; Buwa, L; Okoh, I A

2014-01-01

219

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

220

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

PubMed

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

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

2014-10-01

221

What experimental factors influence the accuracy of retention projections in gas chromatography-mass spectrometry?  

PubMed

Programmed-temperature gas chromatographic (GC) retention information is difficult to share because it depends on so many experimental factors that vary among laboratories. Though linear retention indexing cannot properly account for experimental differences, retention times can be accurately calculated, or "projected", from shared isothermal retention vs. temperature (T) relationships, but only if the temperature program and hold-up time vs. T profile produced by a GC is known with great precision. The effort required to measure these profiles were previously impractical, but we recently showed that they can be easily back-calculated from the programmed-temperature retention times of a set of 25 n-alkanes using open-source software at www.retentionprediction.org/gc. In a multi-lab study, the approach was shown to account for both intentional and unintentional differences in the temperature programs, flow rates, and inlet pressures produced by the GCs. Here, we tested 16 other experimental factors and found that only 5 could reduce accuracy in retention projections: injection history, exposure to very high levels of oxygen at high temperature, a very low transfer line temperature, an overloaded column, and a very short column (?15m). We find that the retention projection methodology acts as a hybrid of conventional retention projection and retention indexing, drawing on the advantages of both; it properly accounts for a wide range of experimental conditions while accommodating the effects of experimental factors not properly taken into account in the calculations. Finally, we developed a four-step protocol to efficiently troubleshoot a GC system after it is found to be yielding inaccurate retention projections. PMID:25482038

Wilson, Michael B; Barnes, Brian B; Boswell, Paul G

2014-12-19

222

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

PubMed

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

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

2015-01-01

223

Simultaneous determination of midazolam and its metabolites 1-hydroxymidazolam and 4-hydroxymidazolam in human serum using gas chromatography–mass spectrometry  

Microsoft Academic Search

A method for the quantitation of midazolam and its metabolites 1-hydroxymidazolam and 4-hydroxymidazolam from human serum capable of monitoring concentrations achieved under therapeutic conditions is presented. The substances were extracted under basic conditions with toluene and the hydroxy metabolites transformed to their tert-butyldimethylsilyl derivatives with N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide. The samples were measured by gas chromatography–mass spectrometry. The limits of detection are 0.2

Jens Martens; Peter Banditt

1997-01-01

224

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

225

An alternative method for the determination of estrogens in surface water and wastewater treatment plant effluent using pre-column trimethylsilyl derivatization and gas chromatography\\/mass spectrometry  

Microsoft Academic Search

A procedure using pre-column trimethylsilyl derivatization and gas chromatography\\/ mass spectrometry (GC\\/MS) was developed\\u000a and applied in determining trace estrogens in complex matrix. Main conditions were optimized, including pH value, salinity\\u000a of water sample, elution reagents, clean procedure, derivative solvent and temperature. The optimized method was used to determine\\u000a steroid estrogens in surface water and effluents of wastewater treatment plant

Yiqi Zhou; Jun Zhou; Yiping Xu; Jinmiao Zha; Mei Ma; Zijian Wang

2009-01-01

226

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

227

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

Microsoft Academic Search

A simple, sensitive and accurate method for the analysis of furan in roasted coffee has been used based on headspace–solid-phase micro-extraction (HS–SPME) coupled to gas chromatography–mass spectrometry (GC–MS). The extraction was performed using 75-µm carboxen\\/polydimethylsiloxane fiber. Ionic strength, extraction time and temperature, and desorption time were assessed as the most important parameters affecting the HS–SPME procedure and d4-furan was used

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

2009-01-01

228

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

229

Determination of acetone in human breath by gas chromatography–mass spectrometry and solid-phase microextraction with on-fiber derivatization  

Microsoft Academic Search

Analysis of breath acetone has been used as a diagnostic tool for diabetes. Due to its nature of volatility and activity, it is very difficult to accurately measure the concentration of acetone in human breath by gas chromatography–mass spectrometry (GC–MS). To overcome this problem, we developed a new method using GC–MS and solid-phase microextraction (SPME) with on-fiber derivatization to determine

Chunhui Deng; Jie Zhang; Xiaofeng Yu; Wei Zhang; Xiangmin Zhang

2004-01-01

230

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

NASA Technical Reports Server (NTRS)

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

Tyson, B. J.

1975-01-01

231

Diagnosis of Smith-Lemli-Opitz syndrome by gas chromatography\\/mass spectrometry of 7-dehydrocholesterol in plasma, amniotic fluid and cultured skin fibroblasts  

Microsoft Academic Search

A method is described for quantification of 7-dehydrocholesterol (7DHC) and other neutral sterols by gas chromatography\\/mass spectrometry for diagnosis of Smith-Lemli-Opitz syndrome, an apparent primary defect of cholesterol biosynthesis associated with low plasma levels of cholesterol and high levels of its precursor, 7DHC. Results are summarized for specimens from normal controls and from 40 patients with Smith-Lemli-Opitz syndrome (SLOS). Whereas

Richard I. Kelley

1995-01-01

232

Metabolic profiling of transgenic rice progeny using gas chromatography–mass spectrometry: the effects of gene insertion, tissue culture and breeding  

Microsoft Academic Search

The Bacillus thuringiensis ?-endotoxin and cowpea trypsin inhibitor genes have been introduced into the rice genome to improve its pest resistance via Agrobacterium-mediated transformation. A gas chromatography-mass spectrometry (GC–MS) based metabolic profiling method was employed to\\u000a determine the unpredictable metabolic changes resulting from the gene insertion and tissue culture separately. Descendants\\u000a of the same transformant were obtained from different breeding

Jia Zhou; Lei Zhang; Xiang Li; Yuwei Chang; Qun Gu; Xin Lu; Zhen Zhu; Guowang Xu

233

Development and validation of a quantitative gas chromatography–mass spectrometry method for the detection of endogenous androgens in mouse urine  

Microsoft Academic Search

A quantitative method based on gas chromatography–mass spectrometry (GC–MS) has been developed for the detection of 16 endogenous androgens in the urine of mice. The substances are extracted from 100?L urine with freshly distilled diethyl ether after alkalinisation. The substances are derivatised with a mixture of N-methyl-N-trimethylsilyltrifluoroacetamide\\/NH4I\\/ethanethiol (383\\/1\\/2, v\\/w\\/v) and detected by GC–MS in the selected ion monitoring mode. The

L. Lootens; P. Van Eenoo; P. Meuleman; G. Leroux-Roels; W. Van Thuyne; F. T. Delbeke

2008-01-01

234

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

Microsoft Academic Search

This paper reports the extension of our multiresidue analysis (MA) procedure with 18 natural and synthetic steroids; permitting the identification and quantification, in total of 81 pollutants from one solution, by a single injection, as their trimethylsilyl (TMS)-oxime ether\\/ester derivatives, by gas chromatography–mass spectrometry (GC–MS), within 31min. As a novelty to the field, basic researches, such as fragmentation pattern analysis

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

2011-01-01

235

Diagnosis of Smith-Lemli-Opitz syndrome by gas chromatography\\/mass spectrometry of 7-dehydrocholesterol in plasma, amniotic fluid and cultured skin fibroblasts  

Microsoft Academic Search

A method is described for quantification of 7-dehydrocholesterol (7DHC) and other neutral sterols by gas chromatography\\/mass spectrometry for diagnosis of Smith-Lemli-Opitz syn- drome, an apparent primary defect of cholesterol biosynthesis associated with low plasma levels of cholesterol and high levels of its precursor, 7DHC. Results are summarized for specimens from normal controls and from 40 patients with Smith-Lemli-Opitz syndrome (SLOS).

Richard I. Kelley

236

Complementary fragmentation pattern analysis by gas chromatography–mass spectrometry and liquid chromatography tandem mass spectrometry confirmed the precious lignan content of Cirsium weeds  

Microsoft Academic Search

In this paper, as novelties to the field, it is confirmed at first, that the fruits of Cirsium species, regarded as injurious weeds, do contain lignans, two, different butyrolactone-type glycoside\\/aglycone pairs: the well known arctiin\\/arctigenin and the particularly rare tracheloside\\/trachelogenin species. These experiences were supported by gas chromatography–mass spectrometry (GC–MS), by liquid chromatography tandem mass spectrometry (LC–MS\\/(MS)) and by nuclear

I. Boldizsár; M. Kraszni; F. Tóth; B. Noszál; I. Molnár-Perl

2010-01-01

237

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

Microsoft Academic Search

A simple and sensitive method for the determination of musty odorants, 2-methylisoborneol (MIB) and geosmin (GSM), in environmental water was developed by headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography–mass spectrometry. MIB and GSM were separated within 10min using a DB-1 capillary column and detected in the selective ion monitoring mode. HS-SPME using a polydimethylsiloxane\\/divinylbenzene fiber provided effective sample enrichment,

Keita Saito; Kota Okamura; Hiroyuki Kataoka

2008-01-01

238

Derivatisation\\/solid-phase microextraction followed by gas chromatography–mass spectrometry for the analysis of phenoxy acid herbicides in aqueous samples  

Microsoft Academic Search

Different combinations of derivatisation and solid-phase microextraction followed by gas chromatography–mass spectrometry were optimised and evaluated for the analysis of phenoxy acid herbicides in water. The most successful derivatisation approach was aqueous-phase derivatisation with benzyl bromide. The benzyl esters were extracted most efficiently by the solid-phase microextraction fibre coated with polydimethylsiloxane–divinylbenzene. No carry-over problems were encountered with this fibre upon

Torben Nilsson; Daniela Baglio; Isabel Galdo-Miguez; Jørgen Øgaard Madsen; Sergio Facchetti

1998-01-01

239

Analysis of fatty acids in lung tissues using gas chromatography–mass spectrometry preceded by derivatization-solid-phase microextraction with a novel fiber  

Microsoft Academic Search

In this article, a laboratory-made sol–gel derived fiber with butyl methacrylate\\/hydroxy-terminated silicone oil (BMA\\/OH-TSO) coating was first used for headspace solid-phase microextraction (HS-SPME) of medium and long chain fatty acids after derivatization and applied to the analysis of fatty acids in lung tissues by coupling to gas chromatography–mass spectrometry (GC–MS). The experimental parameters for derivatization, HS-SPME and desorption were optimized.

Dongmei Cha; Mingming Liu; Zhaorui Zeng; Dong’e Cheng; Guoqing Zhan

2006-01-01

240

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

241

Identification of nonprotein amino acids from cycad seeds as N-ethoxycarbonyl ethyl ester derivatives by positive chemical-ionization gas chromatography-mass spectrometry  

Microsoft Academic Search

Nonprotein amino acids from nine species of cycad seeds were analyzed as N-ethoxycarbonyl ethyl ester (ECEE) derivatives by positive chemical-ionization gas chromatography-mass spectrometry. Based on the retention times and mass spectrometry analyses, 12 nonprotein amino acids were identified in these seeds. In addition to the excitatory and putative neurotoxin ß-N-methylamino-l-alanine (BMAA), the known neurotoxin ß-N-oxalylamino-l-alanine (BOAA) was detected from the

Meide Pan; Tom J. Mabry; Ping Cao; Mehdi Moini

1997-01-01

242

The simultaneous identification of metoprolol and its major acidic and basic metabolites in human urine by gas chromatography-mass spectrometry  

SciTech Connect

A novel gas chromatography-mass spectrometric (GC-MS) method was developed to confirm and identify metoprolol and its metabolites by double derivatization with S-(-)menthyl chloroformate [(-)-MCF] and N-methyl(trimethylsilyl-trifluoroacetamide) (MSTFA). This is the first report, which describes the simultaneous identification of metoprolol, its one major acidc and other basic metabolites in human urine based on solid-phase extraction with C{sub 18} reversed-phase cartridges. 12 refs., 4 figs.

Li, Feng; Cooper, S.F. [Universite du Quebec, Pointe-Claire (Canada)

1996-12-31

243

Analysis of deteriorated rubber-based pressure sensitive adhesive by pyrolysis-gas chromatography\\/mass spectrometry and attenuated total reflectance Fourier transform infrared spectrometry  

Microsoft Academic Search

Rubber-based pressure sensitive adhesives of three packing tapes were exposed to sunlight for 6 months to accelerate the oxidation of the adhesives. The exposed adhesives and the unexposed adhesives were analyzed by attenuated total reflectance Fourier transform infrared spectrometry (ATR\\/FT-IR) and pyrolysis-gas chromatography\\/mass spectrometry (Py-GC\\/MS). The ATR\\/FT-IR spectra and the pyrograms changed drastically after the exposure. The pyrolyzate peaks of

Y. Kumooka

2006-01-01

244

Analysis of alkali-lignin in a paper mill effluent decolourised with two Streptomyces strains by gas chromatography–mass spectrometry after cupric oxide degradation  

Microsoft Academic Search

Alkali-lignin samples obtained from an untreated paper mill effluent and from the effluent decolourised by the strains Streptomyces avermitilis CECT 3339 and Streptomyces scabies UAH 51 were analysed by gas chromatography–mass spectrometry (GC–MS) after cupric oxide degradation. The analysis of the depolymerisation products of the alkali-lignin from the decolourised effluents showed a strain specific modification of the aromatic moiety of

Manuel Hernández; Mar??a Jesús Hernández-Coronado; Maria Dolores Montiel; Juana Rodr??guez; Mar??a Enriqueta Arias

2001-01-01

245

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

USGS Publications Warehouse

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

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

2014-01-01

246

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

PubMed

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

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

2014-02-01

247

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

248

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

PubMed

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

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

2012-06-01

249

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

2013-02-01

250

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

251

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

2011-10-01

252

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

PubMed

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

Colley, Valerie L; Casale, John F

2015-03-01

253

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

SciTech Connect

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

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

2010-04-15

254

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

PubMed

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

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

2011-11-01

255

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

PubMed Central

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

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

2012-01-01

256

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

PubMed

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

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

2012-07-01

257

Gas Chromatography -Mass Spectrometry  

E-print Network

compounds are now added to gasoline in many parts of the U.S. They are added to increase the octane number an octane number of 100, and heptane, which is assigned a value of 0. So gasoline with an octane rating a few), there is an increasing number of air pollution regulations in the U.S. and worldwide. Oxygenated

Nizkorodov, Sergey

258

Determination of five abused drugs in nitrite-adulterated urine by immunoassays and gas chromatography-mass spectrometry.  

PubMed

The adulteration of urine specimens with nitrite ion hasseen shown to mask the gas chromatography-mass spectrometry (GC-MS) confirmation testing of marijuana use. This study was designed to further investigate the effect of nitrite adulteration on the detection of five commonly abused drugs by immunoassay screening and GC-MS analysis. The drugs tested are cocaine metabolite (benzoylecgonine), morphine, 11-nor-delta-tetrahydrocannabinol-9-carboxylic acid (THCCOOH), amphetamine, and phencyclidine. The immunoassays evaluated included the instrument-based Abuscreen ONLINE assays, the on-site Abuscreen ONTRAK assays, and the one-step ONTRAK TESTCUP-5 assay. Multianalyte standards containing various levels of drugs were used to test the influence of both potassium and sodium nitrite. In the ONLINE immunoassays, the presence of up to 1.0M nitrite in the multianalyte standards had no significant effect for benzoylecgonine, morphine, and phencyclidine assays. With a high concentration of nitrite, ONLINE became more sensitive for amphetamine (detected more drug than what was expected) and less sensitive for THCCOOH (detected less drug than what was expected). No effects of nitrite were observed on the results of the Abuscreen ONTRAK assays. Similarly, no effects were observed on the absolute qualitative results of the TESTCUP-5 when testing the nitrite-adulterated standards. However, the produced intensities of the signals that indicate the negative test results were slightly lowered in the THC and phencyclidine assays. The presence of 1.0M of nitrite did not show dramatic interference with the GC-MS analysis of benzoylecgonine, morphine, amphetamine, and phencyclidine. In contrast, nitrite ion significantly interfered with the detection of THCCOOH by GC-MS. The presence of 0.03M of nitrite ion resulted in significant loss in the recovery of THCCOOH and its internal standard by GC-MS. The problem of nitrite adulteration could be alleviated by sodium bisulfite treatment even when the specimens were spiked with 1.0M of nitrite ion. Although bisulfite treatment decomposed all nitrite ions in the sample to recover the remaining THCCOOH by GC-MS, the net recovery of THCCOOH depended on urinary pH and time and conditions of sample storage. The presence of nitrite concentrations that might arise from all possible natural sources, including microorganisms, pathological conditions, and medications, did not interfere with the GC-MS analysis of THCCOOH. PMID:9788522

Tsai, S C; ElSohly, M A; Dubrovsky, T; Twarowska, B; Towt, J; Salamone, S J

1998-10-01

259

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

PubMed Central

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 detection, or by matching signal peaks after they have been extracted from chromatogram data matrices. Automated retention time correction is particularly important in non-targeted profiling studies. Results A new approach for matching signal peaks based on dynamic programming is presented. The proposed approach relies on both peak retention times and mass spectra. The alignment of more than two peak lists involves three steps: (1) all possible pairs of peak lists are aligned, and similarity of each pair of peak lists is estimated; (2) the guide tree is built based on the similarity between the peak lists; (3) peak lists are progressively aligned starting with the two most similar peak lists, following the guide tree until all peak lists are exhausted. When two or more experiments are performed on different sample states and each consisting of multiple replicates, peak lists within each set of replicate experiments are aligned first (within-state alignment), and subsequently the resulting alignments are aligned themselves (between-state alignment). When more than two sets of replicate experiments are present, the between-state alignment also employs the guide tree. We demonstrate the usefulness of this approach on GC-MS metabolic profiling experiments acquired on wild-type and mutant Leishmania mexicana parasites. Conclusion We propose a progressive method to match signal peaks across multiple GC-MS experiments based on dynamic programming. A sensitive peak similarity function is proposed to balance peak retention time and peak mass spectra similarities. This approach can produce the optimal alignment between an arbitrary number of peak lists, and models explicitly within-state and between-state peak alignment. The accuracy of the proposed method was close to the accuracy of manually-curated peak matching, which required tens of man-hours for the analyzed data sets. The proposed approach may offer significant advantages for processing of high-throughput metabolomics data, especially when large numbers of experimental replicates and multiple sample states are analyzed. PMID:17963529

Robinson, Mark D; De Souza, David P; Keen, Woon Wai; Saunders, Eleanor C; McConville, Malcolm J; Speed, Terence P; Liki?, Vladimir A

2007-01-01

260

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

261

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

2004-01-01

262

Urine benzodiazepine screening using Roche Online KIMS immunoassay with beta-glucuronidase hydrolysis and confirmation by gas chromatography- mass spectrometry.  

PubMed

Performance of the Roche Online KIMS (kinetic interaction of microparticles in solution) benzodiazepine (BZD) immunoassay (IA) with and without beta-glucuronidase treatment was evaluated on a Hitachi Modular automated IA analyzer calibrated using nordiazepam at 100 ng/mL. Reproducibility, linearity, accuracy, sensitivity, and interferences were evaluated. Precision of the assay (percent coefficient of variation (%CV)) with and without addition of the enzyme was less than 6% and 9%, respectively, with linearity (r(2) value of 0.9578 and 0.9746), respectively. Between-run precision of a 125 ng/mL nordiazepam control (n = 287) over 67 days, produced a %CV of 13.6% for the hydrolytic assay. Modification of the BZD assay to include automated hydrolysis of urinary BZD glucuronide conjugates was evaluated using three glucuronidated BZD standards prepared at concentrations ranging from 250 to 10,000 ng/mL. With hydrolysis, temazepam, oxazepam, and lorazepam glucuronides, produced cross-reactivities of 25%, 15%, and 20%, respectively. Without hydrolysis, the glucuronidated BZD standards produced less than 1% cross-reactivity in the assay. The ability of the assay to differentiate between positive and negative samples was evaluated by assaying 20 negative urine samples and serial dilutions of certified drug-free urine fortified with 28 different BZDs. All of the negative and positive urine samples produced the appropriate screening result. Cross-reactivities of 27 different BZDs, calculated as the normalized IA response divided by the BZD concentration that produced a response approximately equivalent to the response of a 100 ng/mL nordiazepam standard and multiplied by 100, ranged from 15% to 149%. Human urine samples (n = 28) that were previously found to contain BZDs by gas chromatography-mass spectrometry (GC-MS) also produced a positive BZD IA result. The IA was challenged with 78 potentially interfering compounds, and none produced a positive BZD response. As a part of the validation, a large number of human urine samples (29,500) were assayed using the modified Online BZD IA method to evaluate the performance of the method in production. Of the 29,500 samples tested, 80 produced a positive IA result. Analysis by GC-MS confirmed the presence of at least 1 BZD compound in 61 of the samples corresponding to a confirmation rate of 76%. The Online BZD IA modified by the automatic addition of beta-glucuronidase appears well adapted for the rapid detection of BZDs and their metabolites in human urine. PMID:15842763

Klette, Kevin L; Wiegand, Russell F; Horn, Carl K; Stout, Peter R; Magluilo, Joseph

2005-04-01

263

[Simultaneous determination of chloramphenicol, thiamphenicol, and florfenicol residues in animal tissues by gas chromatography/mass spectrometry].  

PubMed

A method was developed for the simultaneous determination of chloramphenicol (CAP), thiamphenicol (TAP), and florfenicol (FF) residues in animal tissues using gas chromatography/mass spectrometry (GC/MS) with chemical ionization source in negative mode. The homogenized samples were extracted with ethyl acetate and the extracts were partitioned with n-hexane to remove lipids. Further cleanup was performed on a florisil cartridge and the purified samples were derivatized with Sylon BFT [N, O-bis (trimethylsilyl) trifluoroacetamide (BSTFA)-trimethylchlorosilane (TMCS), 99: 1, v/v] in toluene. Meta-nitrochloramphenicol (m-CAP) was used as the internal standard for the determination. Selected ion monitoring (SIM) was used for detection, ions were chosen, respectively, for the monitoring at m/z 432, 466, 468, 470 for m-CAP, m/z 376, 378, 466, 468 for CAP, m/z 409, 411, 499, 501 for TAP, and m/z 339, 341, 429, 431 for FF. Quantitative ions were selected at m/z 466 for CAP and m-CAP, at m/z 339 for FF and at m/z 409 for TAP. The detection limits were 0.03 microg/kg for CAP, 0.2 microg/kg for FF and TAP. The correlation coefficients were above 0.99 for the calibration curves of the medicines. The linear ranges were 0.1 - 8.0 microg/kg for CAP and 0.2 - 4.0 microg/kg for FF and TAP. The reproducibilities of the compounds within a batch were 5.5%, 10.4%, and 8.8% for CAP, FF, and TAP respectively, while the corresponding values between the batches were 7.4%, 20.7%, and 19.1%. The recoveries were 80.0% - 111.5%, and the relative standard deviations were 1.2% - 15.4%. The method is applicable for detection of the residues in animal derived food, such as pork, poultry and aquatic products. PMID:16827302

Li, Peng; Qiu, Yueming; Cai, Huixia; Kong, Ying; Tang, Yingzhang; Wang, Daning; Xie, Mengxia

2006-01-01

264

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

PubMed

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

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

2015-01-23

265

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

2005-11-01

266

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

PubMed

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

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

2014-10-01

267

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

USGS Publications Warehouse

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

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

2006-01-01

268

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

269

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

270

[Determination of antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) in cosmetics by gas chromatography-mass spectrometry selected ion method].  

PubMed

A new method for the determination of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) in cosmetics by gas chromatography-mass spectrometry selected ion storage (SIS) method was developed. The BHA and BHT in samples were extracted by methanol. The m/z 165 and m/z 205 were the monitoring ion for BHA and BHT respectively. The detection limits of BHA and BHT in samples were 2.5 micrograms/g and 0.5 microgram/g, respectively. The method is simple, rapid and accurate. PMID:12541980

Zhang, Wei-Ya; Wu, Cai-Ying; Wang, Cheng-Yun; Yang, Zuo-Jun; Liu, Li

2002-03-01

271

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

PubMed Central

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

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

2010-01-01

272

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

2013-06-19

273

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

PubMed

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

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

2012-03-01

274

Off-odor compounds produced in cork by isolated bacteria and fungi: a gas chromatography-mass spectrometry and gas chromatography-olfactometry study.  

PubMed

The risk of development of specific olfactory profiles in cork was evaluated after inoculation of cork granules and agglomerated and natural cork stoppers with isolated bacteria and fungi. The highest incidence of off-odor development was found in assays when fungi were inoculated. Cork granules with musty-earthy, musty-earthy-TCA, and vegetative deviations were inspected by gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). Sixteen odor zones were clearly recognized in the GC-O analyses. Among these, octanal, 2-methoxy-3,5-dimethylpyrazine (MDMP), Z-2-nonenal, 2-methylisoborneol, 2,4,6-trichloroanisole (TCA), geosmin, and guaiacol were the most significant odorants and helped in the discrimination of sensory deviations. Only TCA and guaiacol were detected above their respective detection limits by HS-SPME-GC-MS. The fungi Cryptococcus sp. isolate F020, Rhodotorula sp. isolate F025, Penicillium glabrum isolate F001, and Pennicillium variabile F003A and the bacterium Pseudomonas jessenii isolate A1 were found to produce TCA to a greater extent. Additionally, 13 of 38 isolated microorganisms (2 bacteria and 11 fungi) proved able to produce unpleasant musty-earthy or vegetative odors that were not related to a significant TCA accumulation. PMID:19639991

Prat, Chantal; Trias, Rosalia; Culleré, Laura; Escudero, Ana; Anticó, Enriqueta; Bañeras, Lluís

2009-08-26

275

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

PubMed

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

Seisonen, Sirli; Kivima, Evelin; Vene, Kristel

2015-02-15

276

Analysis by gas chromatography-mass spectrometry of the essential oil from the aerial parts of Pimpinella junoniae Ceb. & Ort., gathered in La Gomera, Canary Islands, Spain.  

PubMed

The essential oil from the aerial parts of Pimpinella junoniae Ceb. & Ort., growing in La Gomera, Canary Islands, Spain, was studied by gas chromatography and gas chromatography-mass spectrometry, and 43 constituents were identified. The major components were found to be alpha-zingiberene (20.6%), alpha-pinene (17.9%), (E)-beta-farnesene (9.3%), ar-curcumene (7.4%), beta-phellandrene (7.0%), beta-bisabolene (6.1%) and epoxypseudoisoeugenyl 2-methylbutyrate (6.0%). The decomposition product of epoxypseudoisoeugenol derivatives, 5-methoxy-2-methylbenzofuran (5.7%), moderate amounts of other arylpropanoids with the pseudoisoeugenol skeleton (total percentage, 5.2%) and other compounds such as beta-sesquiphellandrene (3.0%), cis-beta-guaiene (1.5%), alpha-phellandrene (1.5%) and alpha-bisabolol (1.3%), were also found. PMID:14518782

Velasco-Negueruela, A; Pérez-Alonso, M J; Pérez de Paz, P L; Paúl-Palá, J; Sanz, J

2003-09-01

277

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

PubMed

A new multi-dimensional analytical method using gas chromatography-nitrogen phosphorus detection (GC-NPD) and gas chromatography-mass spectrometry (GC-MS) was developed for qualitative and quantitative measurement of lincomycin and spectinomycin residues in food animal tissues. This method is based on a new extraction procedure using accelerated solvent extraction (ASE). The analytes were extracted by phosphate buffer with trichloroacetic acid deproteinization and clean-up by C?? solid-phase extraction (SPE) adding dodecanesulfonic acid sodium salt as an ion-pair reagent. The eluted fraction was evaporated and derivatised with N,O-bis(trimethylsilyl) trifluoroacetamide (BSTFA) for GC-NPD analysis and GC-MS confirmation. Parameters for extraction pressure, temperature and cycle of ASE, clean-up, derivatisation and analysis procedure were optimised. The method was validated in muscle, kidney and liver of swine, bovine with a low concentration (limit of quantification) of 16.4 and 21.4 µg kg?¹ for these two analytes using GC-NPD. For GC-MS, the limits of quantification were 4.1 and 5.6 µg kg?¹, respectively. Spiked recoveries from levels of 20 to 200 µg kg?¹ were found to be between 73% and 99% with a relative standard deviation (RSD) of less than 17% in GC-NPD. For GC-MS, levels from 5 to 20 µg kg?¹ had between 70% and 93% with an RSD of less than 21%. This rapid and reliable method can be used for the characterisation and quantification of residues of lincomycin and spectinomycin in animal tissues. PMID:21240824

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

2011-02-01

278

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

PubMed

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

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

2015-01-01

279

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

PubMed Central

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

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

2015-01-01

280

Simultaneous determination of midazolam and its metabolites 1-hydroxymidazolam and 4-hydroxymidazolam in human serum using gas chromatography-mass spectrometry.  

PubMed

A method for the quantitation of midazolam and its metabolites 1-hydroxymidazolam and 4-hydroxymidazolam from human serum capable of monitoring concentrations achieved under therapeutic conditions is presented. The substances were extracted under basic conditions with toluene and the hydroxy metabolites transformed to their tert-butyldimethylsilyl derivatives with N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide. The samples were measured by gas chromatography-mass spectrometry. The limits of detection are 0.2 ng ml(-1) for midazolam and 0.1 ng ml(-1) for 1-hydroxy- and 4-hydroxymidazolam. The coefficients of variation are 3.9% at 5 ng ml(-1) for midazolam, 6.7% at 2 ng ml(-1) for 1-hydroxymidazolam and 8.8% (22.2%) at 0.5 (0.2) ng ml(-1) for 4-hydroxymidazolam. PMID:9187388

Martens, J; Banditt, P

1997-04-25

281

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

PubMed

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

Freitas, Lissara Aparecida de Souza; Vieira, André Coutinho; Mendonça, João Antônio Felipe Risolia; Figueiredo, Eduardo Costa

2014-02-01

282

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

283

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

PubMed

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

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

2015-01-01

284

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

PubMed

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

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

2014-11-28

285

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

286

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

USGS Publications Warehouse

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

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

1994-01-01

287

Ignitable liquid identification using gas chromatography/mass spectrometry data by projected difference resolution mapping and fuzzy rule-building expert system classification.  

PubMed

The gasoline and kerosene collected from different locations in the United States were identified by gas chromatography/mass spectrometry (GC/MS) followed by chemometric analysis. Classifications based on two-way profiles and target component ratios were compared. The projected difference resolution (PDR) mapping was applied to measure the differences among the ignitable liquid (IL) samples by their GC/MS profiles quantitatively. Fuzzy rule-building expert systems (FuRESs) were applied to classify individual ILs. The FuRES models yielded correct classification rates greater than 90% for discriminating between samples. PDR mapping, a new method for characterizing complex data sets was consistent with the FuRES classification result. PMID:22472078

Lu, Weiying; Rankin, J Graham; Bondra, Alexandria; Trader, Carolyn; Heeren, Amanda; Harrington, Peter de B

2012-07-10

288

Identification of nonprotein amino acids from cycad seeds as N-ethoxycarbonyl ethyl ester derivatives by positive chemical-ionization gas chromatography-mass spectrometry.  

PubMed

Nonprotein amino acids from nine species of cycad seeds were analyzed as N-ethoxycarbonyl ethyl ester (ECEE) derivatives by positive chemical-ionization gas chromatography-mass spectrometry. Based on the retention times and mass spectrometry analyses, 12 nonprotein amino acids were identified in these seeds. In addition to the excitatory and putative neurotoxin beta-N-methylamino-L-alanine (BMAA), the known neurotoxin beta-N-oxalylamino-L-alanine (BOAA) was detected from the seeds of Macrozamia moorei and M. communis, and delta-N-oxalyl-ornithine was obtained from the Cycas revoluta seeds. A novel nonprotein amino acid named cycasindene, previously reported from C. revoluta, was also found in the seeds of members of the C. angulata and C. rumphii complex. Eight additional known nonprotein amino acids were also identified. This is the first report of the neurotoxin BOAA from cycad seeds. PMID:9409004

Pan, M; Mabry, T J; Cao, P; Moini, M

1997-11-01

289

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

SciTech Connect

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

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

1994-05-01

290

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

PubMed

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

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

2014-02-26

291

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

PubMed Central

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

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

2014-01-01

292

Determination of musty-odor compounds in water by gas chromatography-mass spectrometry with a needle-type sample-preparation device.  

PubMed

The musty-odor compounds (MOCs) 2-methylisoborneol (2-MIB) and geosmin in water samples were determined by a purge-and-trap method using a needle-type extraction device followed by gas chromatography-mass spectrometry. For the extraction of these compounds, a triple-layer-type extraction needle containing divinylbenzene and activated carbon particles as the particulate extraction media was introduced. Several experimental parameters, including the sample temperature during extraction, the addition of sodium chloride, and desorption conditions, were thoroughly optimized in this study. The detection limits for 2-MIB and geosmin were 1.0 and 0.5 ng L(-1), respectively. The method was successfully applied to the simultaneous determination of MOCs and other volatile organic compounds in tap-water samples. PMID:25312628

Ueta, Ikuo; Mitsumori, Tomoki; Kawakubo, Susumu; Saito, Yoshihiro

2014-01-01

293

Method development for the analysis of 1,4-dioxane in drinking water using solid-phase extraction and gas chromatography-mass spectrometry.  

PubMed

1,4-Dioxane has been identified as a probable human carcinogen and an emerging contaminant in drinking water. The United States Environmental Protection Agency's (U.S. EPA) National Exposure Research Laboratory (NERL) has developed a method for the analysis of 1,4-dioxane in drinking water at ng/L concentrations. The method consists of an activated carbon solid-phase extraction of 500-mL or 100-mL water samples using dichloromethane as the elution solvent. The extracts are analyzed by gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode. In the NERL laboratory, recovery of 1,4-dioxane ranged from 94-110% in fortified laboratory reagent water and recoveries of 96-102% were demonstrated for fortified drinking water samples. The relative standard deviations for replicate analyses were less than 6% at concentrations exceeding the minimum reporting level. PMID:19161654

Grimmett, Paul E; Munch, Jean W

2009-01-01

294

Determination of phthalates in wine by headspace solid-phase microextraction followed by gas chromatography-mass spectrometry. Use of deuterated phthalates as internal standards.  

PubMed

This study proposes the use of deuterated phthalates as internal standards for the accurate determination of phthalates in wine by headspace solid-phase microextraction followed by gas chromatography-mass spectrometry. Unlike other internal standards proposed previously such as benzyl benzoate, deuterated phthalates enabled matrix-error free determinations to be performed without standard addition because statistically equal slopes were obtained for synthetic, white, rose and red wines. The relative standard deviation values under intermediate precision conditions ranged from 0.24 to 4.6%, and detection limits below 35 ng L(-1) were obtained. Recovery values were around 100% in most of cases and the method provided similar results to standard addition. Finally, the method was used to screen phthalate levels in 10 wine samples. PMID:18191868

Carrillo, J D; Martínez, M P; Tena, M T

2008-02-15

295

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

PubMed Central

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

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

2014-01-01

296

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

297

Determination of testosterone in plasma from men by gas chromatography/mass spectrometry, with high-resolution selected-ion monitoring and metastable peak monitoring  

SciTech Connect

Highly specific methods are described for determining testosterone in plasma or serum from men. Extract fractions obtained by selective isolation procedures are converted to tert-butyldimethylsilyl (TBDMS) oximes/TBDMS ethers or methyl oximes/TBDMS ethers and analyzed by gas chromatography/mass spectrometry in the high-resolution selected-ion monitoring or metastable peak-monitoring modes. (2H3)Testosterone and unlabeled 17-epitestosterone are used as the respective internal standards. When we applied the two procedures to analysis of samples of pooled plasma and serum used for external quality assessment of routine assays, the results agreed well. Interlaboratory values for mean concentrations obtained by routine immunoassays (y) consistently exceeded values obtained by our technique (x), although the values closely correlated (r . 0.997; y . 1.008x + 0.564 nmol/L).

Finlay, E.M.; Gaskell, S.J.

1981-07-01

298

A rapid and definitive diagnosis of kerosene dermatitis by an analysis of detached lesional epidermis using gas chromatography-mass spectrometry.  

PubMed

A 73-year-old woman, who suffered from erythema with bullae and pustules on her abdomen and anterior right thigh, visited our hospital without an awareness of the causative agents. The lesions appeared like first and second degree burns. The small amount of detached roof of bulla was sampled without skin biopsy before the ointment treatment. The sample was sonicated in an ultrasonic bath for 1 min in n-pentane, and then 1 mul of the extract was analyzed by gas chromatography-mass spectrometry (GC-MS). The causative agent was determined to be kerosene. An examination of blood samples collected at the first visit failed to detect kerosene, though traces of trimethylbenzene were detected. A GC-MS analysis of the small sample of lesional epidermis was very useful to identify kerosene as a causative agent. PMID:15902481

Tsujino, Yoshio; Hieda, Yoko; Morita, Eishin

2005-08-01

299

Analysis of polycyclic aromatic hydrocarbons in contaminated soil by Curie point pyrolysis coupled to gas chromatography-mass spectrometry, an alternative to conventional methods.  

PubMed

Curie point pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) has been compared with classical extraction procedures (Soxhlet, sonication, KOH digestion, microwave-assisted) followed by GC-MS analysis for the determination of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil. In each case, the efficiency of the technique was examined for 16 PAHs included in the US Environmental Protection Agency Priority Pollutant List. The results indicate that the recovery of PAHs is dependent on the extraction technique. The highest recoveries of PAHs were obtained with Curie point pyrolysis and KOH digestion. Py-GC-MS appeared to be interesting alternative method for the determination of PAHs in contaminated soil. The results were validated by certified soil (CRM 104) analysis. PMID:14763749

Buco, S; Moragues, M; Doumenq, P; Noor, A; Mille, G

2004-02-13

300

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

2005-06-01

301

Analysis of alkali-lignin in a paper mill effluent decolourised with two Streptomyces strains by gas chromatography-mass spectrometry after cupric oxide degradation.  

PubMed

Alkali-lignin samples obtained from an untreated paper mill effluent and from the effluent decolourised by the strains Streptomyces avermitilis CECT 3339 and Streptomyces scabies UAH 51 were analysed by gas chromatography-mass spectrometry (GC-MS) after cupric oxide degradation. The analysis of the depolymerisation products of the alkali-lignin from the decolourised effluents showed a strain specific modification of the aromatic moiety of the alkali-lignin. Moreover, both strains were able to breakdown the aryl-alkyl ether linkages between the cinnamic acids and the lignin. Finally, GC-MS analysis showed that both strains oxidised the alkali-lignin regardless of its initial degree of oxidation. PMID:11442046

Hemández, M; Hernández-Coronado, M J; Montiel, M D; Rodríguez, J; Arias, M E

2001-06-15

302

Identification of intact long-chain p-hydroxycinnamate esters in leaf fibers of abaca (Musa textilis) using gas chromatography/mass spectrometry.  

PubMed

The study of acetone-extractable components from the leaf fibers of the non-wood plant abaca (Musa textilis) resulted in the isolation and identification of series of intact hydroxycinnamate esters consisting of ferulic and p-coumaric acids esterified to long-chain fatty alcohols (C20 to C28) and omega-hydroxyfatty acids (C22 to C28). These series of compounds were characterized by high-temperature gas chromatography/mass spectrometry (GC/MS) using capillary columns (12 m length) with thin films that allowed the analysis of intact (i.e., without prior saponification) hydroxycinnamate esters. Characterization of intact individual compounds was achieved based on the mass spectra obtained by GC/MS of the underivatized compounds and their methyl and/or trimethylsilyl ether derivatives. PMID:15487024

del Río, José C; Rodríguez, Isabel M; Gutiérrez, Ana

2004-01-01

303

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

PubMed

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

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

2014-08-22

304

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

NASA Astrophysics Data System (ADS)

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

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

2008-10-01

305

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

EPA Science Inventory

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

306

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...

307

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

PubMed

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

Niebler, Johannes; Buettner, Andrea

2015-01-01

308

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

PubMed

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-17alpha-methyltestosterone I are presented. A new metabolite 4-chloro-3alpha, 6 beta, 17beta-trihydroxy-17alpha-methyl-5beta-androst-l-en-16-one was isolated by high performance liquid chromatography (HPLC) from urine following a single oral administration of 40 mg of I and characterized. Metabolite II was excreted into urine with a maximum excretion rate at approximately 48 h after administration and could be detected by gas chromatography/high resolution mass spectrometry (GC/HRMS) for up to 14 days. Two further partly characterized metabolites III and IV were confirmed for more than 9 days. The same three metabolites, II-IV, in varying amounts were also detected in urine samples from athletes who administered I. PMID:8639473

Schanzer, W; Horning, S; Opfermann, G; Donike, M

1996-03-01

309

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

310

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

PubMed

A sensitive and solvent-less method for the determination of musty and earthy off-flavor compounds, 2-methylisoborneol (MIB) and geosmin (GSM), in salmon tissue was developed using stir bar sorptive extraction-thermal desorption coupled with gas chromatography-mass spectrometry (SBSE-TD-GCMS). MIB and GSM were solid phase extracted using polydimethylsiloxane (PDMS) coated stir bars, analyzed by gas chromatography, and detected in full scan mode of mass selective detector (MSD). Using this method, the calibration curves of MIB and GSM were linear in the range of 0.3-100ng/L, with a correlation coefficient above 0.999 and RSDs less than 4% (n=4). The limit of detection (LOD, S/N=3, n=6) and limit of quantification (LOQ, S/N=10, n=6) of MIB and GSM were both ?0.3 and 1ng/L, respectively. The recoveries of MIB and GSM were 22% and 29% by spike in 30ng/L standard compounds, 23% and 30% by spike-in 100ng/L standard compounds in salmon tissue samples with good precision (<8% of RSDs, n=6), respectively. The recoveries of MIB and GSM were better than reported methodologies using SPME fibres (<10%) in fish tissue samples. This method was successfully applied to monitor and characterize depurated salmon fillet samples (0, 3, 6 and 10 days). PMID:24252650

Ruan, E D; Aalhus, J L; Summerfelt, S T; Davidson, J; Swift, B; Juárez, M

2013-12-20

311

Sample preparation for analyzing polycyclic aromatic hydrocarbons and polychlorinated dibenzo-p-dioxins and dibenzofurans in sediment by gas chromatography/mass spectrometry  

SciTech Connect

A sample preparation technique was developed to isolate and separate two classes of combustion-produced pollutants: three- to six-ring polycyclic aromatic hydrocarbons (PAH) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F), from sediment samples for interference-free analyses by gas chromatography/mass spectrometry (GC/MS). The method involves soxhlet extraction with methylene chloride, sulfur removal with activated copper powder, gel filtration chromatography with Sephadex LH-20, polarity separation of PAH and PCDD/F with prepacked silica gel solid-phase extraction columns, and isolation of PCDD/F from polychlorinated biphenyls with microalumina columns. Stringent procedural controls were established to achieve clean isolations and recoveries of 70% or better for each step in the method. The prepared sample extracts were analyzed by capillary GC and GC/MS. Electron impact ionization was used for PAH, and negative chemical ionization with methane as a reagent gas was used for PCDD/F. Reproducible results were obtained. The method is sample and has the advantage of conserving sample consumption since two classes of compounds can be analyzed from the same sample. This can be critical in sediment core analyses were sample size is usually limited. 23 refs., 3 tabs.

Tan, Y.L.; Kong, Ada; Chiu, Yue-On (Department of Energy, New York, NY (United States))

1993-12-01

312

Positional isomerization of trans-3-hexadecenoic acid employing 2-amino-2-methyl-propanol as a derivatizing agent for ethylenic bond location by gas chromatography/mass spectrometry.  

PubMed

The effect of derivatization with 2-amino-2-methyl-propanol on trans-3-hexadecenoic acid was investigated as part of the identification of the trans-3-hexadecenoic acid in two Nova Scotian seaweeds. After the extraction of the total fatty acids and their methylation, the monoenoic trans fraction was isolated by thin-layer chromatography on silica gels impregnated with silver nitrate. This fraction was first analyzed by gas chromatography and showed the presence of the trans-3-hexadecenoic acid; other fatty acids were not present. The isolated fraction was derivatized with 2-amino-2-methyl-propanol prior to analysis by gas chromatography/mass spectrometry. The chromatogram obtained showed the presence of a positional isomer formed during the derivatization of the trans-3-hexadecenoic acid. The mass spectrum showed a prominent [M+H] and diagnostic ions for the identification of the unknown isomer, corresponding to the 4,4-dimethyloxazoline (DMOX) derivative of a presumed 2-hexadecenoic acid. Definitive confirmation of the ethylenic bond position was obtained by oxidative ozonolysis of the DMOX derivatives of the fatty acids under investigation. Infrared spectroscopy showed that the artifact formed during the DMOX derivatization of trans-3-hexadecenoic acid was the DMOX derivative of cis-2-hexadecenoic acid. PMID:7503411

Lamberto, M; Ackman, R G

1995-09-20

313

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

PubMed

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

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

2014-08-01

314

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

EPA Science Inventory

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

315

Differentiation of types of crude oils in polluted soil samples by headspace-fast gas chromatography–mass spectrometry  

Microsoft Academic Search

The coupling of a headspace sampler to a fast gas chromatography system with mass spectrometry detection is proposed as a method for the identification of the sources of contamination in soils due to the presence of hydrocarbons derived from petroleum. The samples are subjected to the headspace generation process, with no prior treatment, and the volatiles generated are separated by

José Luis Pérez Pavón; Armando Guerrero Peña; Carmelo García Pinto; Bernardo Moreno Cordero

2006-01-01

316

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

PubMed

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

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

2014-03-01

317

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

SciTech Connect

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

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

2008-11-13

318

High concentration capacity sample preparation techniques to improve the informative potential of two-dimensional comprehensive gas chromatography-mass spectrometry: application to sensomics.  

PubMed

This study reports and critically discusses the results of a systematic investigation on the effectiveness of different and complementary sampling approaches, based on either sorption and adsorption, treated as a further dimension of a two-dimensional comprehensive gas chromatography-mass spectrometry analytical platform for sensomics. The focus is on the potentials of a group of high concentration capacity (HCC) sample preparation (Solid Phase Microextraction, SPME, Stir Bar Sorptive Extraction, SBSE and Headspace Sorptive Extraction, HSSE) and Dynamic Headspace (D-HS) techniques investigated to provide information useful for fingerprinting and profiling studies of food aroma. Volatiles and semi-volatiles contributing to define whole and nonfat dry milk aroma have been successfully characterized thanks to the combination of effective and selective sampling by HCC and D-HS techniques, high separation and detection power of GC×GC-MS and suitable data elaboration (i.e., Comprehensive Template Matching Fingerprinting - CTMF). Out of the sample preparation techniques investigated, HSSE and SBSE have shown to be really effective for sensomics studies because of their high concentration factors, providing highly representative profiles as well as analyte recovery suitable for GC-Olfactometry even with high odor threshold (OT) markers or potent odorants in sub-trace amounts. PMID:24144305

Cordero, Chiara; Cagliero, Cecilia; Liberto, Erica; Nicolotti, Luca; Rubiolo, Patrizia; Sgorbini, Barbara; Bicchi, Carlo

2013-11-29

319

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

PubMed

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

Abdulra'uf, Lukman Bola; Tan, Guan Huat

2013-12-15

320

Enzymatic digestion and selective quantification of underivatised delta-9-tetrahydrocannabinol and cocaine in human hair using gas chromatography-mass spectrometry.  

PubMed

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. PMID:22567573

Breidi, Salah Eddine; Barker, James; Petróczi, Andrea; Naughton, Declan P

2012-01-01

321

Simultaneous determination of cotinine and trans-3-hydroxycotinine in urine by automated solid-phase extraction using gas chromatography–mass spectrometry  

PubMed Central

A gas chromatography–mass spectrometry method was developed and validated for the simultaneous automated solid-phase extraction and quantification of cotinine and trans-3-hydroxycotinine in human urine. Good linearity was observed over the concentration ranges studied (R2 > 0.99). The limit of quantification was 10 ng/mL for both analytes. The limits of detection were 0.06 ng/mL for cotinine (COT) and 0.02 ng/mL for trans-3-hydroxycotinine (OH-COT). Accuracy for COT ranged from 0.98 to 5.28% and the precision ranged from 1.24 to 8.78%. Accuracy for OH-COT ranged from ?2.66 to 3.72% and the precision ranged from 3.15 to 7.07%. Mean recoveries for cotinine and trans-3-hydroxycotinine ranged from 77.7 to 89.1%, and from 75.4 to 90.2%, respectively. This analytical method for the simultaneous measurement of cotinine and trans-3-hydroxycotinine in urine will be used to monitor tobacco smoking in pregnant women and will permit the usefulness of trans-3-hydroxycotinine as a specific biomarker of tobacco exposure to be determined. © 2014 The Authors. Biomedical Chromatography published by John Wiley & Sons Ltd. PMID:24616054

Chiadmi, Fouad; Schlatter, Joël

2014-01-01

322

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

PubMed

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 5-500 ng/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 medium and high quality control samples. Recovery range was 36.2-83.7%. Placenta samples were kept at -80 degrees C until analysis; analytes were stable after three freeze-thaw cycles (samples stored at -20 degrees C). This accurate and precise assay has sufficient sensitivity and specificity for the analysis of specimens collected from women who voluntarily terminated their pregnancy at 12th week of gestation. The method has proven to be robust and accurate for the quantification of the principal recreational drugs of abuse in this period of the prenatal life. This is the first report that highlights the presence of drugs of abuse during the first trimester of gestation. PMID:20056364

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

2010-03-20

323

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

PubMed

Gas chromatography/mass spectrometry (GC/MS) with negative ion chemical ionization (NICI) detection was utilized for quantitative determination of nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) in diesel particulate-related standard reference materials (SRMs). Prior to GC/MS analysis, isolation of the nitro-PAHs from the complex diesel particulate extract was accomplished using solid phase extraction (SPE) and normal-phase liquid chromatographic (LC) fractionation using an amino/cyano stationary phase. Concentrations of eight to ten mononitro-PAHs and three dinitropyrenes were determined in three diesel particulate-related SRMs: SRM 1650a Diesel Particulate Matter, SRM 1975 Diesel Particulate Extract, and SRM 2975 Diesel Particulate Matter (Industrial Forklift). The results from GC/MS NICI using two different columns (5% phenyl methylpolysiloxane and 50% phenyl methylpolysiloxane) were compared to each other and to results from two other laboratories for selected nitro-PAHs. 1-Nitropyrene was the most abundant nitro-PAHs in each of the diesel particulate SRMs (19.8+/-1.1 micro g g(-1) particle in SRM 1650a and 33.1+/-0.6 micro g g(-1) particle in SRM 2975). Three dinitropyrene isomers were measured in SRM 1975 at 0.5-1.4 micro g g(-1) extract and in SRM 2975 at 1-3 micro g g(-1) particle. PMID:12589503

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

2003-02-01

324

Solidification of floating organic drop liquid-phase microextraction cell fishing with gas chromatography-mass spectrometry for screening bioactive components from Amomum villosum Lour.  

PubMed

In this study, a novel solidification of floating organic drop liquid-phase microextraction cell fishing with gas chromatography-mass spectrometry (SFOD-LPME-CF-GC-MS) method was established and used to screen, isolate and analyze bioactive components from Amomum villosum Lour. extract. Through comparision of its effect on the models of normal cell and inflammatory cells, anti-inflammatory active components of essential oil from A. villosum Lour. were readily screened, and the components obtained are in agreement with related pharmacological articles. SFOD-LPME-CF-GC-MS was used to analyze the interaction of A. villosum Lour. extracts with normal and lipopolysaccharide-stimulated RAW264.7 macrophage cells. The effect of A. villosum Lour. essential oil extracts in the LPS-stimulated RAW264.7 model were also assessed in terms of cytotoxicity and nitric oxide production as an indication of bioactivity. Three potentially bioactive components were identified, demonstrating that SFOD-LPME-CF-GC-MS can be used successfully in the drug-screening process. This approach avoids the requirement for protein precipitation, but more importantly, generates a high concentration ratio, allowing analysis of trace components in traditional Chinese medicines. SFOD-LPME-CF-GC-MS is a simple, fast, effective and reliable method for the screening and analysis of bioactive components, and it can be extended to screen other bioactive components from TCMs. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25251881

Xue, Xue; Yang, Depo; Wang, Dongmei; Xu, Xinjun; Zhu, Longping; Zhao, Zhimin

2015-04-01

325

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

PubMed

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

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

2004-08-01

326

Molecularly-imprinted microspheres for selective extraction and determination of melamine in milk and feed using gas chromatography-mass spectrometry.  

PubMed

Molecularly-imprinted polymers in the form of microspheres were synthesized using the dispersion polymerization protocol; cyromazine was used as dummy template, while methacrylic acid, ethylene glycol dimethacrylate and acetonitrile (MeCN) were used as functional monomer, cross-linker, and porogen, respectively. When compared with the non-imprinted polymer, the molecularly-imprinted polymers (MIPs) showed outstanding affinity toward melamine in MeCN with a maximum binding concentration (B(max)) of 53.20 nmol mg(-1) MIPs, imprinting effect of 4.6, and a dissociation constant (K(d)) of 90.45 microM. After optimization of the molecularly-imprinted solid-phase extraction conditions, a new method was developed to determine the melamine in milk and feed with gas chromatography-mass spectrometry. The performance of this method has been evaluated in the tainted milk and feed in terms of recovery, precision, linearity, the limit of detection (LOD) and limit of quantitation (LOQ). Recovery ranged in samples from 93.1 to 101.3% with intra-day and inter-day relative standard deviation values below 5.34%. The LOD and LOQ of melamine in milk and feed were 0.01 microg mL(-1) (microg g(-1)) and 0.05 microg mL(-1) (microg g(-1)), respectively. PMID:20674520

Li, Mu; Zhang, Liying; Meng, Zihui; Wang, Zongyi; Wu, Hui

2010-09-01

327

Headspace generation coupled to gas chromatography-mass spectrometry for the automated determination and quantification of endogenous compounds in urine. Aldehydes as possible markers of oxidative stress.  

PubMed

A methodology for the determination of five aldehydes in urine has been developed based on the coupling of a headspace generation sampler with a gas chromatography-mass spectrometry system equipped with a programmed temperature vaporizer. This instrumental configuration minimizes sample manipulation and allows the determination of these compounds without the need for a derivatization step so that the methodology is largely shortened and simplified. An experimental design was carried out in order to optimize the headspace sampling. Sample matrix effect was eliminated by means of dilution of urine samples. The calibration models displayed good linearity (0.1-10 ?g/L) and their validity was checked using ANOVA, and it was observed that they did not exhibit any lack of fit. The LODs obtained ranged between 0.04 and 0.08 ?g/L and the LOQs between 0.12 and 0.24 ?g/L. The accuracy of the method was evaluated in terms of apparent recoveries which were between 86 and 120%. The method developed was applied to the analysis of 17 samples of urine from different subjects in order to quantify these endogenous compounds. PMID:25280875

Antón, Ana Pérez; Ferreira, Ana María Casas; Pinto, Carmelo García; Cordero, Bernardo Moreno; Pavón, José Luis Pérez

2014-11-01

328

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

PubMed

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

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

2013-12-01

329

Rapid analysis of tile industry gaseous emissions by ion mobility spectrometry and comparison with solid phase micro-extraction/gas chromatography/mass spectrometry.  

PubMed

The present paper reports on a rapid method for the analysis of gaseous emissions from ceramic industry, based on ion mobility spectrometry (IMS) as a means for on-site monitoring of volatile organic compounds (VOCs) produced during tile baking. IMS was calibrated with a set of reference compounds (i.e. ethyl acetate, ethanol, ethylene glycol, diethylene glycol, acetaldehyde, formaldehyde, 2-methyl-1,3-dioxolane, 2,2-dimethyl-1,3-dioxolane, 1,3-dioxolane, 1,4-dioxane, benzene, toluene, cyclohexane, acetone, acetic acid) via air-flow permeation. The technique was tested on a laboratory-scale kiln and tiles prepared with selected glycol- and resin-based additives. Finally, the analytical method was applied to emissions from two industries in the Modena (Italy) ceramic area. The results of all experimental phases were compared to those obtained by solid phase micro-extraction/gas chromatography/mass spectrometry (SPME/GC/MS). IMS showed potential as a real-time monitoring device for quality assessment in ceramic industry emissions. IMS spectra, SPME/GC/MS data, relationship between additives/baking conditions and produced VOCs and advantages and limitations of both techniques will be discussed. PMID:17133278

Pozzi, R; Bocchini, P; Pinelli, F; Galletti, G C

2006-12-01

330

A rapid assay for the simultaneous determination of nicotine, cocaine and metabolites in meconium using disposable pipette extraction and gas chromatography-mass spectrometry (GC-MS).  

PubMed

Drug abuse by pregnant women is considered a serious public health problem worldwide. Meconium is the first excretion in newborns and has been used as an alternative matrix to evaluate in utero drug exposure. Solid phase extraction (SPE) is widely employed to prepare and clean up samples in the field of forensic analysis. Most SPE products require large volumes of solvent, which culminates in longer sample processing times and increased cost per sample. Disposable pipette extraction (DPX) tips have been used as an alternative to traditional SPE cartridges. They combine efficient and rapid extraction with reduced solvent consumption. The purpose of this study was to develop and validate a method to determine nicotine, cotinine, cocaine, benzoylecgonine, cocaethylene and methyl ester anhydroecgonine in meconium using DPX and gas chromatography-mass spectrometry (GC-MS). Validation results indicated that extraction efficiency ranged 50-98%, accuracy 92-106%, intra-assay precision 4-12% and inter-assay precision 6-12%. Linear calibration curves resulted in R(2) values >0.99, limits of detection ranged from 2.5 to 15 ng/g and the limit of quantitation from 10 to 20 ng/g. The DPX-GC-MS method was shown to selectively analyze trace concentrations of drugs in meconium samples. Finally, the developed and validated method was applied to 50 meconium samples. PMID:24272386

Mozaner Bordin, Dayanne C; Alves, Marcela N R; Cabrices, Oscar G; de Campos, Eduardo G; De Martinis, Bruno Spinosa

2014-01-01

331

Complex mixture analysis based on gas chromatography-mass spectrometry with time array detection using a beam deflection time-of-flight mass spectrometer.  

PubMed

A beam deflection time-of-flight mass spectrometer was developed in conjunction with an integrating transient recorder to provide time array detection, permitting high mass spectral scan file acquisition rates for complex mixture analysis by capillary gas chromatography-mass spectrometry (GC-MS). Results are presented for the analysis of a urinary organic acid mixture by GC-MS at a scan file acquisition rate of 10 scan files per second (sf/s), showing the advantages of such data collection in the deconvolution of partially resolved components. The reconstructed total ion current (RTIC) chromatogram available from data acquired at this scan file generation rate is shown to be comparable to the profile obtained from a flame ionization detector in representing the chromatography performed under identical experimental parameters. The RTIC chromatogram available from the database obtained at 10 sf/s is compared with that available from a database obtained at 1 sf/s, the latter representing that scan rate typically used with most GC-MS instruments. The advantages of the higher scan file acquisition rate in representing the chromatographic profile and in allowing mass spectral data to be obtained for components in the complex mixture that are unresolved chromatographically are discussed. PMID:1560100

Schultz, G A; Chamberlin, B A; Sweeley, C C; Watson, J T; Allison, J

1992-01-31

332

Simultaneous determination of 2-naphthol and 1-hydroxypyrene in fish and shellfish contaminated with crude oil by gas chromatography-mass spectrometry.  

PubMed

This paper describes a gas chromatography-mass spectrometric method of l-hydroxypyrene (1-HOP) and 2-naphthol (2-NAP) in fish and shellfish. Alkali hydrolysis method in this study was chosen and optimized to the reaction condition for 90 min at 90°C in a 2.0M KOH solution. For five independent determinations at 0.2 and 1.0 ?g/kg, the coefficient of variation was less than 5.1%. This method was used to assess the long-term influence of spilled crude oil on marine ecosystems and analyze fifty-two shellfish samples taken in the near of the accident region of the Hebei Spirit oil spill. 2-NAP and 1-HOP were detected in the mean concentration range of 0.09-12.42 and 0.03-0.06 ?g/kg, respectively. 2-NAP was detected in a high concentration range in shellfishes gathered in 2 months after the accident and it decreased rapidly to 6 months after that. The results showed that 2-NAP might be an important biomarker in biota contaminated with crude oil. PMID:23411178

Lim, Hyun-Hee; Shin, Ho-Sang

2013-06-01

333

Water analysis of the sixteen environmental protection agency-polycyclic aromatic hydrocarbons via solid-phase nanoextraction-gas chromatography/mass spectrometry.  

PubMed

The growing concern with a sustainable environment poses a new challenge to analytical chemists facing the routine monitoring of polycyclic aromatic hydrocarbons (PAHs) in water samples. The new method presented here meets several features of green analytical chemistry. PAHs are extracted from 500 ?L of water sample with 1 mL of a gold nanoparticles aqueous solution and released with 100 ?L of organic solvents for subsequent analysis via gas chromatography/mass spectrometry. The relative standard deviations of the overall procedure ranged from 2.4 (acenaphthene) to 7.8% (dibenz[a,h]anthracene). The limits of detection were excellent as well and varied from 4.94 (fluoranthene) to 65.5 ng L(-1) (fluorene). The excellent analytical figures of merit, the simplicity of the experimental procedure, the short analysis time and the reduced solvent consumption demonstrate the potential of this approach for the routine monitoring of the sixteen priority pollutants via and environmentally friendly methodology. PMID:24794939

Wilson, Walter B; Hewitt, Udienza; Miller, Mattheu; Campiglia, Andres D

2014-06-01

334

Gas chromatography-mass spectrometry metabolite profiling of worker honey bee (Apis mellifera L.) hemolymph for the study of Nosema ceranae infection.  

PubMed

Here, we are presenting a gas chromatography-mass spectrometry (GC/MS) approach for the study of infection of the worker honey bee (Apis mellifera L.) by the newly emerged obligate intracellular parasite Nosema ceranae based on metabolite profiling of hemolymph. Because of the severity of the disease, early detection is crucial for its efficient control. Results revealed that the parasite causes a general disturbance of the physiology of the honey bee affecting the mechanisms controlling the mobilization of energy reserves in infected individuals. The imposed nutritional and energetic stress to the host was depicted mainly in the decreased levels of the majority of carbohydrates and amino acids, including metabolites such as fructose, l-proline, and the cryoprotectants sorbitol and glycerol, which are implicated in various biochemical pathways. Interestingly, the level of glucose was detected at significantly higher levels in infected honey bees. Metabolomics analyses were in agreement with those of multiplex quantitative PCR analyses, indicating that it can be used as a complementary tool for the detection and the study of the physiology of the disease. PMID:22841888

Aliferis, Konstantinos A; Copley, Tanya; Jabaji, Suha

2012-10-01

335

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

336

Dispersive microextraction based on "magnetic water" coupled to gas chromatography/mass spectrometry for the fast determination of organophosphorus pesticides in cold-pressed vegetable oils.  

PubMed

This article presents a novel application of dispersive microextraction based on "magnetic water" (m-water) for the purification of organophosphorus pesticides (methamidophos, omethoate, monocrotophos) from cold-pressed vegetable oils. In the present study, a trace amount of water (extractant) was adsorbed on bare Fe?O? by hydrophilic interaction to form m-water. Rapid extraction can be achieved while the m-water is dispersed in the sample solution with the aid of a vigorous vortex. After extraction, the analyte-adsorbed m-water can be readily isolated from the sample solution by a magnet, which could greatly simplify the operation and reduce the whole pretreatment time. Several parameters affecting the extraction efficiency were investigated, and under the optimized conditions, a simple and effective method for pesticide analysis was established by coupling with gas chromatography/mass spectrometry (GC/MS). The linearity range of the proposed method was 2-100 ng/g with satisfactory correlation coefficients (R) of 0.9997-0.9998, and the limits of quantification (LOQ) for the target compounds were in the range of 0.70-1.27 ng/g. In addition, the reproducibility was obtained by evaluating the intra- and interday precisions with relative standard deviations (RSDs) less than 7.2% and 6.5%, respectively. Finally, the established "magnetic water" microextraction method was successfully applied for the determination of pesticide residues in several kinds of cold-pressed vegetable oils. PMID:23687955

Zhao, Qin; Lu, Qian; Yu, Qiong-Wei; Feng, Yu-Qi

2013-06-01

337

[Determination of 46 plasticizers in food contact polyvinyl chloride packaging materials and their migration into food simulants by gas chromatography-mass spectrometry].  

PubMed

A gas chromatography-mass spectrometry (GC-MS) method was developed for the determination of 46 plasticizers in food contact polyvinyl chloride (PVC) packaging materials and their migration into food simulants, i. e. water, 3% acetic acid, 10% ethanol and olive oil. Plasticizers in the PVC packaging materials, aqueous food simulants and olive oil food simulants were extracted by the dissolution-precipitation, liquid-liquid extraction and gel permeation chromatography (GPC) approaches, respectively. The extracts were analyzed by GC-MS in selective ion monitoring (SIM) mode and quantified using the external standard method. The cal-ibration curves were linear in the ranges of 0.1-2.0 mg/L with the correlation coefficients of 0.9910-0. 999 9. The limits of detection were from 0. 005 mg/kg to 0. 05 mg/kg ( S/N = 5 ). The recoveries at 3 spiked levels were 69.51%-107. 21% and the relative standard deviations (RSDs n = 6) ranged from 3.53% to 18.95%. These results show that this method is fast, sensitive and accurate for the qualitative and quantitative determination of plasticizers in food contact plastic products and 4 types of food simulants. PMID:21574398

Guo, Chunhai; Bo, Haibo; Duan, Wenzhong; Jia, Haitao; Chen, Ruichun; Ma, Yusong; Ai, Lianfeng

2011-01-01

338

Optimization of an isotope dilution gas chromatography/mass spectrometry method for the detection of endogenous estrogen metabolites in urine samples.  

PubMed

A gas chromatography/mass spectrometry (GC/MS) method for the simultaneous quantitation of ten estrogen metabolites in human urine was optimized. The method consists of initial enzymatic hydrolysis of the estrogen conjugates using beta-glucuronidase followed by solid-phase extraction (SPE) on Sep-pak C18 columns and further sample purification by ion-exchange chromatography on QAE-Sephadex cartridges in the acetate form. QAE-Sephadex cartridges in the borate form were used to separate estrogens into two fractions: one fraction containing estrogens lacking vicinal cis-hydroxyls (Fr 1) and another containing estrogens possessing vicinal cis-hydroxyls (catecholestrogens; Fr 2). Finally, following O-trimethylsilyl ether derivatization, the estrogens were analyzed by GC/MS in the selected ion monitoring mode. Estrogens were quantitated using deuterated internal standards, which were added to the samples at the initiation of the work-up procedures. After addition to estrogen-low male human samples the standards showed good chromatographic linear response and reproducibility. A reduction in the number of steps and improvements in the robustness of the work-up procedures were achieved. The modified method described is less complex, amenable to use with commercially available SPE columns and fulfils all the reliability criteria, resulting in highly specific and accurate results. PMID:17569095

Knust, Ulrike; Strowitzki, Thomas; Spiegelhalder, Bertold; Bartsch, Helmut; Owen, Robert Wyn

2007-01-01

339

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

340

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

PubMed

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

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

2015-06-15

341

Determination of dissolved-phase pesticides in surface water from the Yakima River basin, Washington, using the Goulden large-sample extractor and gas chromatography/mass spectrometry  

USGS Publications Warehouse

Concentrations of pesticides in the dissolved phase of surface water samples from the Yakima River basin, WA, were determined using preconcentration in the Goulden large-sample extractor (GLSE) and gas chromatography/ mass spectrometry (GC/MS) analysis. Sample volumes ranging from 10 to 120 L were processed with the GLSE, and the results from the large-sample analyses were compared to those derived from 1-L continuous liquid-liquid extractions. Few of the 40 target pesticides were detected in 1-L samples, whereas large-sample preconcentration in the GLSE provided detectable levels for many of the target pesticides. The number of pesticides detected in GLSE processed samples was usually directly proportional to sample volume, although the measured concentrations of the pesticides were generally lower at the larger sample volumes for the same water source. The GLSE can be used to provide lower detection levels relative to conventional liquid-liquid extraction in GC/MS analysis of pesticides in samples of surface water. ?? 1993 American Chemical Society.

Foster, G.D.; Gates, P.M.; Foreman, W.T.; McKenzie, S.W.; Rinella, F.A.

1993-01-01

342

Optimization of a Solid-Phase Microextraction method for the Gas Chromatography-Mass Spectrometry analysis of blackberry (Rubus ulmifolius Schott) fruit volatiles.  

PubMed

A Solid-Phase Microextraction method for the Gas Chromatography-Mass Spectrometry analysis of blackberry (Rubus sp.) volatiles has been fully optimized by means of a Box-Behnken experimental design. The optimized operating conditions (Carboxen/Polydimethylsiloxane fiber coating, 66°C, 20min equilibrium time and 16min extraction time) have been applied to the characterization for the first time of the volatile composition of Rubus ulmifolius Schott blackberries collected in Italy and Spain. A total of 74 volatiles of different functionality were identified; esters and aliphatic alcohols were the predominant classes in both sample types. Methylbutanal (2.02-25.70%), ethanol (9.84-68.21%), 2,3-butanedione (2.31-14.71%), trans-2-hexenal (0.49-17.49%), 3-hydroxy-2-butanone (0.08-7.39%), 1-hexanol (0.56-16.39%), 1-octanol (0.49-10.86%) and methylbutanoic acid (0.53-21.48%) were the major compounds in most blackberries analyzed. Stepwise multiple regression analysis of semiquantitative data showed that only two variables (ethyl decanoate and ethyl acetate) were necessary for a successful differentiation of blackberries according to their harvest location. PMID:25704677

D'Agostino, M F; Sanz, J; Sanz, M L; Giuffrè, A M; Sicari, V; Soria, A C

2015-07-01

343

Determination of Wastewater Compounds in Whole Water by Continuous Liquid-Liquid Extraction and Capillary-Column Gas Chromatography/Mass Spectrometry  

USGS Publications Warehouse

A method for the determination of 69 compounds typically found in domestic and industrial wastewater is described. The method was developed in response to increasing concern over the impact of endocrine-disrupting chemicals on aquatic organisms in wastewater. This method also is useful for evaluating the effects of combined sanitary and storm-sewer overflow on the water quality of urban streams. The method focuses on the determination of compounds that are indicators of wastewater or have endocrine-disrupting potential. These compounds include the alkylphenol ethoxylate nonionic surfactants, food additives, fragrances, antioxidants, flame retardants, plasticizers, industrial solvents, disinfectants, fecal sterols, polycyclic aromatic hydrocarbons, and high-use domestic pesticides. Wastewater compounds in whole-water samples were extracted using continuous liquid-liquid extractors and methylene chloride solvent, and then determined by capillary-column gas chromatography/mass spectrometry. Recoveries in reagent-water samples fortified at 0.5 microgram per liter averaged 72 percent ? 8 percent relative standard deviation. The concentration of 21 compounds is always reported as estimated because method recovery was less than 60 percent, variability was greater than 25 percent relative standard deviation, or standard reference compounds were prepared from technical mixtures. Initial method detection limits averaged 0.18 microgram per liter. Samples were preserved by adding 60 grams of sodium chloride and stored at 4 degrees Celsius. The laboratory established a sample holding-time limit prior to sample extraction of 14 days from the date of collection.

Zaugg, Steven D.; Smith, Steven G.; Schroeder, Michael P.

2006-01-01

344

Multiresidue method for the determination of pharmacologically active substances in egg and honey using a continuous solid-phase extraction system and gas chromatography-mass spectrometry.  

PubMed

A sensitive, selective, efficient gas chromatography-mass spectrometry method for the simultaneous determination of 22 pharmacologically active substances (antibacterials, nonsteroidal antiinflammatories, antiseptics, antiepileptics, lipid regulators, ?-blockers and hormones) in eggs and honey was developed. The sample pretreatment includes precipitation of proteins and lipids with acetonitrile:water (3:2, v/v), centrifugation and continuous solid-phase extraction for cleanup and preconcentration. The proposed method was validated with quite good analytical results including limits of detection of 0.4-3.3ng/kg for 2g of sample and good linearity (r(2)>0.995) throughout the studied concentration ranges. The recoveries of analytes from real honey and egg samples spiked at concentrations of 15-2000ng/kg fell in the range 87-102%, with relative standard deviations from 2.6% to 7.0%. The method was successfully used to determine the target compounds in various types of eggs (hen, quail and duck) and honey samples (flower, forest, acacia, sunflower, clover and pine tree). Two samples of hen eggs bought at supermarkets and one of quail eggs were found to contain florfenicol, pyrimethamine, estrone and 17?-estradiol at levels from 0.095 to 2.7?g/kg. PMID:25704684

Azzouz, Abdelmonaim; Ballesteros, Evaristo

2015-07-01

345

Development and validation of a gas chromatography/mass spectrometry procedure for confirmation of para-toluenesulfonamide in edible fish fillet tissue  

USGS Publications Warehouse

Chloramine-T is a disinfectant being developed as a treatment for bacterial gill disease in cultured fish. As part of the drug approval process, a method is required for the confirmation of chloramine-T residues in edible fish tissue. The marker residue that will be used to determine the depletion of chloramine-T residues from the edible tissue of treated fish is para-toluenesulfonamide (p-TSA), a metabolite of chloramine-T. The development and validation of a procedure for the confirmation of p-TSA is described. Homogenized fish tissue is dried by mixing with anhydrous sodium sulfate, and the mixture is extracted with methylene chloride. The extract is passed through a silica gel solid-phase extraction column, from which p-TSA is subsequently eluted with acetonitrile. The acetonitrile extract is evaporated, and the oily residue is dissolved in hexane. The hexane solution is shaken with fresh acetonitrile. The acetonitrile solution is evaporated and the residue is redissolved in dilute potassium hydroxide solution. The aqueous solution is extracted with methylene chloride to further remove more of the fat co-extractive. The aqueous solution is reacted with pentafluorobenzyl bromide in presence of tetrabutylammonium hydrogensulfate. The resulting di-(pentafluorobenzyl) derivative of p-TSA is analyzed by gas chromatography/mass spectrometry. This method permits the confirmation of p-TSA in edible fish tissue at 20 ppb.

Idowu, O.R.; Kijak, P.J.; Meinertz, J.R.; Schmidt, L.J.

2004-01-01

346

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

PubMed Central

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

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

2015-01-01

347

A simple and sensitive single-step method for gas chromatography-mass spectrometric determination of fipronil and its metabolites in sugarcane juice, jaggery and sugar.  

PubMed

A simple and sensitive single-step method for gas chromatography-mass spectrometric determination of fipronil and its metabolites viz., fipronil desulfinyl, fipronil sulphide and fipronil sulphone in sugarcane juice, jaggery and sugar has been developed. Acetonitrile was superior to ethyl acetate in terms of selectivity, though they were on par with each other in terms of recoveries. This method does not require any cleanup as the PSA-based cleanup was on par with no-cleanup treatment. Interestingly, the recoveries of fipronil and its metabolites decreased with increased amounts of C18 from 10 to 50mg/g of matrix. Matrix effects were insignificant and the limit of quantification was 0.005?g/g. The recoveries of fipronil and its metabolites varied between 87.5% and 108.5% with the RSD of 0.2-5.3% for all the three matrices studied. This method has also been validated by monitoring fipronil and its metabolites in the retail outlet samples of sugarcane juice, jaggery and sugar. PMID:24360469

Ramasubramanian, Thirumalaiandi; Paramasivam, Mariappan; Jayanthi, Ramabhadran; Chandrasekaran, Subramaniam

2014-05-01

348

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

PubMed

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

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

2013-01-01

349

A method by homemade OH/TSO-PMHS fibre solid-phase microextraction coupling with gas chromatography-mass spectrometry for analysis of antiestrogens in biological matrices.  

PubMed

A kind of homemade solid-phase microextraction fibre coupled with gas chromatography-mass spectrometry (GC-MS) was developed for trace analysis of antiestrogens (tamoxifen, cis- and trans-clomiphene) in biological matrices. In this method, derivatization was unnecessary and sample solution could be injected directly after very simple deproteinization operation. The conditions of influencing adsorption of the solid-phase microextraction (SPME) fibre and desorption of the analytes were investigated in details. Matrix effects were studied in different background. Under optimum conditions, the proposed method was further validated by spiking analytes into rabbit liver solutions. Linear ranges of tamoxifen, cis- and trans-clomiphene were 0.02-2.56, 0.08-2.56 and 0.16-2.56 ng mL(-1), respectively. The limits of quantitation were in the range of 0.02-0.16 ng mL(-1). The intra-day accuracy was ranged 96.2-106.2% and precision were in the range of 5.1-8.7%. The extraction recoveries of the antiestrogens in rabbit liver solution were between 73.8% and 113.1%, and R.S.D.s were from 3.6% to 14.1%. The results show that the homemade sol-gel coating is suitable for determination of trace antiestrogens in complex matrices. The proposed approach was proved to be rapid, simple, easy, sensitive and reproducible for trace analysis of antiestrogens in biological matrices. PMID:19046677

Liu, Wei; Zhang, Lan; Chen, Shengping; Duan, Hongbin; Chen, Xi; Wei, Zhenyi; Chen, Guonan

2009-01-01

350

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

PubMed

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

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

2009-02-27

351

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

PubMed

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

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

2015-07-01

352

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. PMID:23661995

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

2013-01-01

353

[Simultaneous determination of 23 ester compounds in cigarette water-borne adhesives by liquid-liquid extraction and gas chromatography-mass spectrometry].  

PubMed

A method of gas chromatography-mass spectrometry (GC-MS) with liquid-liquid extraction has been developed for the simultaneous determination of 23 ester compounds including acetate esters, acrylic esters, metacrylic acid esters and phthalate acid esters in cigarette water-borne adhesives. After dispersed in water, the sample was extracted by n-hexane solution containing phenyl ethyl propionate as internal standard substance. Then, the solution was centrifuged and filtrated through a 0.45 microm organic membrane filter. Finally, the solution was separated on a DB-WAXETR column (60 m x 0.25 mm x 0.25 microm), and detected with MS in selected ion monitoring mode, and quantified by internal standard method. The results showed a good linear correlation in the range of 0.4-50.0 mg/L. The recoveries of the ester compounds spiked in the sample were 81.8%-109.1%, and the relative standard deviations (RSDs, n = 5) were less than 4%. The limits of detection (LODs) and limits of quantification (LOQs were in the ranges of 0.02-0.76 mg/kg and 0.04-2.52 mg/kg, respectively. The method is simple, time-saving, and has high sensitivity and good reproducibility. It can be applied to the determination of the 23 ester compounds in cigarette water-borne adhesives. PMID:24432642

Gong, Shuguo; Kong, Bo; Tuo, Suxing; Dai, Yunhui; Wu, Mingjian; Tan, Liquan; Liu, Wei

2013-10-01

354

Development and validation of a gas chromatography/mass spectrometry procedure for confirmation of para-toluenesulfonamide in edible fish fillet tissue.  

PubMed

Chloramine-T is a disinfectant being developed as a treatment for bacterial gill disease in cultured fish. As part of the drug approval process, a method is required for the confirmation of chloramine-T residues in edible fish tissue. The marker residue that will be used to determine the depletion of chloramine-T residues from the edible tissue of treated fish is para-toluenesulfonamide (p-TSA), a metabolite of chloramine-T. The development and validation of a procedure for the confirmation of p-TSA is described. Homogenized fish tissue is dried by mixing with anhydrous sodium sulfate, and the mixture is extracted with methylene chloride. The extract is passed through a silica gel solid-phase extraction column, from which p-TSA is subsequently eluted with acetonitrile. The acetonitrile extract is evaporated, and the oily residue is dissolved in hexane. The hexane solution is shaken with fresh acetonitrile. The acetonitrile solution is evaporated and the residue is redissolved in dilute potassium hydroxide solution. The aqueous solution is extracted with methylene chloride to further remove more of the fat co-extractive. The aqueous solution is reacted with pentafluorobenzyl bromide in presence of tetrabutylammonium hydrogensulfate. The resulting di-(pentafluorobenzyl) derivative of p-TSA is analyzed by gas chromatography/mass spectrometry. This method permits the confirmation of p-TSA in edible fish tissue at 20 ppb. PMID:15493666

Idowu, Olutosin R; Kijak, Philip J; Meinertz, Jeffery R; Schmidt, Larry J

2004-01-01

355

Fourier-transform infrared spectroscopy and gas chromatography-mass spectrometry reveal a remarkable degree of structural damage in the DNA of wild fish exposed to toxic chemicals.  

PubMed Central

The use of gas chromatography-mass spectrometry with selected ion monitoring (GC-MS/SIM) and Fourier-transform infrared (FT-IR) spectroscopy revealed a remarkable degree of damage in the hepatic DNA of fish exposed to toxic environmental chemicals, compared with controls. The exposed fish, which were neoplasm-free, were part of a population with a high incidence of liver cancer. GC-MS/SIM showed markedly high concentrations of hydroxyl radical-induced ring-opening products (e.g., 2,6-diamino-4-hydroxy-5-formamidopyrimidine) and 8-hydroxy adducts of adenine and guanine (e.g., 8-hydroxyguanine) in the DNA. FT-IR spectroscopy revealed substantial changes in spectral areas, such as those assigned to NH vibrations of nucleotide bases and CO vibrations of deoxyribose. This diverse and extensive damage to DNA provides a perspective of premalignant changes resulting from xenobiotic exposure and a promising basis for predicting cancer risk in animals and humans. Images Fig. 1 PMID:7809168

Malins, D C; Gunselman, S J

1994-01-01

356

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

PubMed

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

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

2014-07-01

357

Simultaneous detection and quantification of select nitromusks, antimicrobial agent, and antihistamine in fish of grocery stores by gas chromatography-mass spectrometry.  

PubMed

Continually detected biologically persistent nitromusks; galaxolide (HHCB), tonalide (AHTN) and musk ketone (MK), antimicrobial triclosan (TCS), and antihistamine diphenhydramine (DPH) were examined for the first time in edible fillets originating from eight fish species grown in salt- and fresh-water. The sampled fish collected from local grocery stores were homogenized, extracted, pre-concentrated and analyzed by gas chromatography-mass spectrometry (GC-MS) using selected ion monitoring (SIM). The presence of the target compounds in fish extracts was confirmed based on similar mass spectral features and retention behavior with standards. Internal standard based calibration plots were used for quantification. The HHCB, AHTN, TCS and DPH were consistently observed with concentration of 0.163-0.892, 0.068-0.904, 0.189-1.182, and 0.942-7.472 ng g(-1), respectively. These values are at least 1-3 orders of magnitude lower than those obtained in environmental fish specimens. The MK was not detected in any fish. PMID:24377446

Foltz, James; Abdul Mottaleb, M; Meziani, Mohammed J; Rafiq Islam, M

2014-07-01

358

Identification of volatile butyl rubber thermal-oxidative degradation products by cryofocusing gas chromatography/mass spectrometry (cryo-GC/MS).  

SciTech Connect

Chemical structure and physical properties of materials, such as polymers, can be altered as aging progresses, which may result in a material that is ineffective for its envisioned intent. Butyl rubber formulations, starting material, and additives were aged under thermal-oxidative conditions for up to 413 total days at up to 124 %C2%B0C. Samples included: two formulations developed at Kansas City Plant (KCP) (%236 and %2310), one commercially available formulation (%2321), Laxness bromobutyl 2030 starting material, and two additives (polyethylene AC-617 and Vanax MBM). The low-molecular weight volatile thermal-oxidative degradation products that collected in the headspace over the samples were preconcentrated, separated, and detected using cryofocusing gas chromatography mass spectrometry (cryo-GC/MS). The majority of identified degradation species were alkanes, alkenes, alcohols, ketones, and aldehydes. Observations for Butyl %2310 aged in an oxygen-18 enriched atmosphere (18O2) were used to verify when the source of oxygen in the applicable degradation products was from the gaseous environment rather than the polymeric mixture. For comparison purposes, Butyl %2310 was also aged under non-oxidative thermal conditions using an argon atmosphere.

Smith, Jonell Nicole; White, Michael Irvin; Bernstein, Robert; Hochrein, James Michael

2013-02-01

359

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

PubMed

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

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

2010-10-01

360

Quantitation of total homocysteine in human plasma by derivatization to its N(O,S)-propoxycarbonyl propyl ester and gas chromatography-mass spectrometry analysis.  

PubMed

Much evidence supports the hypothesis that mild or moderate hyperhomocysteinaemia represents an important and independent risk factor for occlusive vascular diseases. Therefore, the accurate and reliable determination of total plasma homocysteine has gained major importance for risk assessment. Furthermore, it can help in the detection of folate and vitamin B12 deficiency. This has prompted us to develop a sensitive gas chromatography-mass spectrometry (GC-MS) method in order to quantify total homocysteine in human plasma. Prior to chromatography, reduced homocysteine was released from disulfide bonds by incubation with excess dithiothreitol and converted into its N(O,S)-propoxycarbonyl propyl ester by derivatization with n-propyl chloroformate. Aminoethylcysteine served as internal standard. The method proved to be highly linear over the entire concentration range examined (corresponding to 0-266 microM homocysteine) and showed intra-assay and inter-assay variation (relative standard deviations) of approximately 5 and 5-10%, respectively. External quality control by comparison with duplicate analysis performed on a HPLC-based system revealed satisfactory correlation. The newly developed GC-MS based method provides simple, reliable and fast quantification of total homocysteine and requires only inexpensive chemicals, which are easy to obtain. PMID:9291598

Sass, J O; Endres, W

1997-08-01

361

Gas chromatography-mass spectrometry determination of earthy-musty odorous compounds in waters by two phase hollow-fiber liquid-phase microextraction using polyvinylidene fluoride fibers.  

PubMed

A rapid and sensitive method for the determination of earthy-musty odorous compounds, 2-methylisoborneol, 2-isopropyl-3-methoxy pyrazine, 2,4,6-trichloroanisole, 2,3,6-trichloroanisole, and geosmin, in water samples has been developed. The method was based on coupling a new polyvinylidene fluoride (PVDF) hollow-fiber liquid-phase microextraction system with gas chromatography-mass spectrometry (GC-MS). The PVDF hollow fibers have high porosity and an enhanced solvent compatibility for extraction of the target analytes. Experimental conditions were optimized by investigating the type of extraction solvent, sample pH, sodium chloride concentration, stirring speed, extraction time, and GC-MS conditions. Under optimized conditions, the earthy-musty odorous compounds exhibited good linearity (R>0.995) in the concentration range of 6.2-250ng/L. The repeatability and reproducibility of the method were lower than 6.8% and 9.8%, respectively. The limit of detection and limit of quantification values were lower than 2.0 and 6.2ng/L, respectively. The analysis of different water samples such as tap, pond, rive and waste water indicated minimal matrix effects. Analyte recoveries for real samples spiked at different concentrations were between 84.4% and 117.5%. PMID:24456707

Yu, Shengbing; Xiao, Qin; Zhu, Binghui; Zhong, Xiuhua; Xu, Yinghua; Su, Guangning; Chen, Min

2014-02-14

362

Stir bar sorptive extraction and trace analysis of selected endocrine disruptors in water, biosolids and sludge samples by thermal desorption with gas chromatography-mass spectrometry.  

PubMed

Stir bar sorptive extraction (SBSE) in combination with thermal desorption coupled to gas chromatography-mass spectrometry (GC-MS) was successfully applied to analyze a range of endocrine disrupting compounds (EDCs) in wastewater, solids and sludge. The targeted EDCs include sex steroid hormones, phthalates, alkylphenols and tamoxifen. Recovery for the EDCs using this analytical technique ranged from 44% to 128%. Limit of detection (LOD) of the compounds was 2.0 ng/L for water samples and 0.02 ng/g for solid samples, whereas the limit of quantitation (LOQ) was 5.0 ng/L for water samples and 0.06 ng/g for solid samples. When this analytical technique was applied to measure EDC concentration in a biological nutrient removal (BNR) wastewater treatment plant located in South East Queensland, Australia, the results showed that there were high amounts of phthalates, alkylphenols and female hormones present in the raw influent wastewater and solids. These concentrations were dramatically reduced after passing through the various treatment zones of the bioreactor (anaerobic, aerobic and anoxic). PMID:17706739

Tan, Benjamin L L; Hawker, Darryl W; Müller, Jochen F; Tremblay, Louis A; Chapman, Heather F

2008-01-01

363

Simultaneous determination of UV filters and polycyclic musks in aqueous samples by solid-phase microextraction and gas chromatography-mass spectrometry.  

PubMed

A simple, precise and accurate method for the simultaneous determination of four UV filters and five polycyclic musks (PCMs) in aqueous samples was developed by solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS). The operating conditions affecting the performance of SPME-GC-MS, including fiber thickness, desorption time, pH, salinity, extraction time and temperature have been carefully studied. Under optimum conditions (30 ?m PDMS fiber, 7 min desorption time, pH 7, 10% NaCl, 90 min extraction time at 24°C), the correlation coefficients (r(2)) of the calibration curves of target compounds ranged from 0.9993 to 0.9999. The limit of detection (LOD) and limit of quantification (LOQ) ranged from 0.2 to 9.6 ng L?¹ and 0.7 to 32.0 ng L?¹, respectively. The developed procedure was applied to the determinations of four UV filters and five PCMs in river water samples and internal standard was used for calibration to compensate the matrix effect. Good relative recoveries were obtained for spiked river water at low, medium and high levels. The proposed SPME method was compared with traditional SPE procedure and the results found in river water using both methods were in the same order of magnitude and both are quite agreeable. PMID:20580369

Liu, Hongtao; Liu, Ling; Xiong, Yiquan; Yang, Xuemei; Luan, Tiangang

2010-10-22

364

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

PubMed

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

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

2015-04-01

365

Combination of direct infusion mass spectrometry and gas chromatography mass spectrometry for toxicometabolomic study of red blood cells and serum of mice Mus musculus after mercury exposure.  

PubMed

Although mercury (Hg) is an important environmental and occupational pollutant, its toxicological effects, especially in serum and red blood cells (RBCs), have been scarcely studied. A toxicometabolomics workflow based on high resolution mass spectrometry approaches has been applied to investigate the toxicological effects of Hg in Mus musculus mice after subcutaneous injection for 10 days, which produced inflammation and vacuolization, steatosis and karyolysis in the hepatic tissue. To this end, direct infusion mass spectrometry (DIMS) of polar and lipophilic extracts from serum and RBCs, using positive and negative mode of acquisition (ESI+/ESI-), and gas chromatography-mass spectrometry were used. A quantitative analysis of reversible oxidized thiols in serum proteins demonstrated a strong oxidative stress induction in the liver of Hg-exposed mice. Endogenous metabolites alterations were identified by partial least squares-discriminant analysis (PLS-DA). Mercury-exposed mice show perturbations in energy metabolism, amino acid metabolism, membrane phospholipid breakdown and oxidative stress-related metabolites in serum along the exposure. This work reports for the first time the effects of Hg-exposure on RBCs metabolic pathways, and reveals disturbances in glycolysis, membrane turnover, glutathione and ascorbate metabolisms. PMID:25660718

García-Sevillano, M A; García-Barrera, T; Navarro, F; Abril, N; Pueyo, C; López-Barea, J; Gómez-Ariza, J L

2015-03-15

366

Assessment of povidone-iodine disinfectant compatibility with antimicrobial incise drape and adhesion inhibition on the skin using a gas chromatography/mass spectrometry approach.  

PubMed

According to orthopedists' reports, substitution of the original for a generic povidone-iodine (PVP-I) disinfectant could have led to some adhesion problems of antimicrobial incise drapes on the field of operation with the consequence of increasing the infection risk. Three methods have been used to assess the case: (a) a gas chromatography/mass spectrometry (GC-MS) approach quantifying methimazole formation from carbimazole, (b) in vitro adhesion experiments on a smooth glass plate surface and (c) the analysis of intrasurgical procedures. GC-MS results confirmed the higher potency of the original compared to the generic PVP-I. In vitro comparison of the adhesion on a PVP-I-pretreated glass surface showed no difference between the disinfectants and no significant destruction of the adhesive layer. However, due to different surgery preparation procedures, the remaining free skin surface granting sufficient adhesion differed if the intervening surgeon himself or his assistant prepared the field of operation. As a conclusion, the original PVP-I disinfectant is confirmed as the first-choice disinfectant for the field of operation. Adhesion problems were arising with new surgical staff and thus different preparation procedures. Exchanging PVP-I disinfectants cannot explain the adhesion problems of drapes and antimicrobial incise foils on the skin. PMID:16490977

Jenzer, Herbert

2006-01-01

367

Gas chromatography-mass spectrometry method optimized using response surface modeling for the quantitation of fungal off-flavors in grapes and wine.  

PubMed

An optimized method for the quantitation of volatile compounds responsible for off-aromas, such as earthy odors, found in wine and grapes was developed. The method involved a fast and simple headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) for simultaneous determination of 2-isopropyl-3-methoxypyrazine, 2-isobutyl-3-methoxypyrazine, 3-octanone, fenchone, 1-octen-3-one, trans-2-octen-1-ol, fenchol, 1-octen-3-ol, 2-methylisoborneol, 2,4,6-trichloroanisole, geosmin, 2,4,6-tribromoanisole, and pentachloroanisole. The extraction of the temperature and time were optimized using response surface methodology in both wine base (WB) and grape base (GB). Low limits of detection (0.1-5 ng/L in WB and 0.05-1.6 in GB) and quantitation (0.3-17 in WB and 0.2-6.2 in GB) with good recoveries (83-131%) and repeatability [4.3-9.8% coefficient of variation (CV) in WB and 5.1-11.1% CV in GB] and reproducibility (3.6-10.2 in WB and 1.9-10.9 in GB) indicate that the method has excellent sensitivity and is suitable for the analysis of these off-flavor compounds in wine and grape juice samples. PMID:25703150

Sadoughi, Navideh; Schmidtke, Leigh M; Antalick, Guillaume; Blackman, John W; Steel, Christopher C

2015-03-25

368

Determination of atranol and chloroatranol in perfumes using simultaneous derivatization and dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry.  

PubMed

A new analytical method based on simultaneous derivatization and dispersive liquid-liquid microextraction (DLLME) followed by gas chromatography-mass spectrometry (GC-MS), for the determination of the allergenic compounds atranol and chloroatranol in perfumes, is presented. Derivatization of the target analytes by means of acetylation with anhydride acetic in carbonate buffer was carried out. Thereby volatility and detectability were increased for improved GC-MS sensitivity. In addition, extractability by DLLME was also enhanced due to a less polar character of the solutes. A liquid-liquid extraction was performed before DLLME to clean up the sample and to obtain an aqueous sample solution, free of the low polar matrix from the essential oils, as donor phase. Different parameters, such as the nature and volume of both the extraction and disperser solvents, the ionic strength of the aqueous donor phase or the effect of the derivatization reagent volume, were optimized. Under the selected conditions (injection of a mixture of 750?L of acetone as disperser solvent, 100?L of chloroform as extraction solvent and 100?L of anhydride acetic as derivatization reagent) the figures of merit of the proposed method were evaluated. Limits of detection in the low ngmL(-1) range were obtained. Matrix effect was observed in real perfume samples and thus, standard addition calibration is recommended. PMID:24793850

López-Nogueroles, Marina; Chisvert, Alberto; Salvador, Amparo

2014-05-15

369

Determination of eight pharmaceuticals in an aqueous sample using automated derivatization solid-phase microextraction combined with gas chromatography-mass spectrometry.  

PubMed

An automated aqueous derivatization solid-phase microextraction (SPME) coupled with a gas chromatography/mass spectrometry (GC/MS) method was developed for simultaneous determination of eight pharmaceuticals in water samples. Dimethyl sulfate and tetrabutylammonium hydrogen sulfate were selected as derivatization and activation reagents for the esterification reaction. An experimental design approach, central composition design (CCD), was employed to investigate and optimize the operative factors influencing the extraction efficiency, including extraction time, extraction temperature and ionic strength. The other parameters such as type of fiber coating, pH and derivatization conditions were also evaluated. SPME was finally carried out in headspace mode at 80°C for 60min with the presence of 3.00g Na2SO4, using a home-made 44?m PDMS fiber. Wide linear ranges and low limits of detection (0.06-1.24ngL(-1)) were obtained under the optimized conditions. The relative standard deviations (RSDs) and recoveries ranged from 0.5% to 12.3% and 85% to 110%, respectively. The proposed method was successfully applied to the analysis of the real surface water samples from the Pearl River Estuary. PMID:25703003

Huang, Siming; Zhu, Fang; Jiang, Ruifen; Zhou, Shichun; Zhu, Derong; Liu, Hong; Ouyang, Gangfeng

2015-05-01

370

Metabolic flux analysis of Arthrobacter sp. CGMCC 3584 for cAMP production based on 13C tracer experiments and gas chromatography-mass spectrometry.  

PubMed

Arthrobacter sp. CGMCC 3584 are able to produce cAMP from glucose by the purine synthesis pathway via de novo or salvage biosynthesis. In order to gain an improved understanding of its metabolism, (13)C-labeling experiment and gas chromatography-mass spectrometry (GC-MS) analysis were employed to determine the metabolic network structure and estimate the intracellular fluxes. GC-MS analysis helps to reflect the activity of the intracellular pathways and reactions. The metabolic network mainly contains glycolytic and pentose phosphate pathways, the tricarboxylic acid cycle, and the inactive glyoxylate shunt. Hypoxanthine as a precursor of cAMP and sodium fluoride as an inhibitor of glycolysis were found to increase the cAMP production, as well as the flux through the PP pathway. The effects of adding hypoxanthine and sodium fluoride are discussed based on the enzyme assays and metabolic flux analysis. In conclusion, our results provide quantitative insights into how cells manipulate the metabolic network under different culture conditions and this may be of value in metabolic regulation for desirable production. PMID:24056081

Niu, Huanqing; Chen, Yong; Yao, Shiwei; Liu, Lixia; Yang, Chen; Li, Bingbing; Liu, Dong; Xie, Jingjing; Chen, Xiaochun; Wu, Jinglan; Ying, Hanjie

2013-12-01

371

Rapid analysis of Fructus forsythiae essential oil by ionic liquids-assisted microwave distillation coupled with headspace single-drop microextraction followed by gas chromatography-mass spectrometry.  

PubMed

A rapid, green and effective miniaturized sample preparation and analytical technique, i.e. ionic liquids-assisted microwave distillation coupled with headspace single-drop microextraction (ILAMD-HS-SDME) followed by gas chromatography-mass spectrometry (GC-MS) was developed for the analysis of essential oil (EO) in Fructus forsythiae. In this work, ionic liquids (ILs) were not only used as the absorption medium of microwave irradiation but also as the destruction agent of plant cell walls. 1-Ethyl-3-methylimidazolium acetate ([C2mim]OAc) was chosen as the optimal ILs. Moreover, n-heptadecane (2.0 ?L) was selected as the appropriate suspended solvent for the extraction and concentration of EO. Extraction conditions of the proposed method were optimized using the relative peak area of EO constituents as the index, and the optimal operational parameters were obtained as follows: irradiation power (300 W), sample mass (0.7 g), mass ratio of ILs to sample (2.4), temperature (78°C) and time (3.4 min). In comparison to previous reports, the proposed method was faster and required smaller sample amount but could equally monitor all EO constituents with no significant differences. PMID:24267075

Jiao, Jiao; Ma, Dan-Hui; Gai, Qing-Yan; Wang, Wei; Luo, Meng; Fu, Yu-Jie; Ma, Wei

2013-12-01

372

Development and validation of a sensitive thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) method for the determination of phosgene in air samples.  

PubMed

A new rapid, sensitive and reliable method was developed for the determination of phosgene in air samples using thermal desorption (TD) followed by gas chromatography-mass spectrometry (GC-MS). The method is based on a fast (10 min) active sampling of only 1 L of air onto a Tenax® GR tube doped with 0.5 mL of derivatizing mixture containing dimercaptotoluene and triethylamine in hexane solution. Validation of the TD-GC-MS method showed a low limit of detection (40 ppbv), acceptable repeatability, intermediate fidelity (relative standard deviation within 12 %) and excellent accuracy (>95%). Linearity was demonstrated for two concentration ranges (0.04 to 2.5 ppmv and 2.5 to 10 ppmv) owing to variation of derivatization recovery between low and high concentration levels. Due to its simple on-site implementation and its close similarity with recommended operating procedure (ROP) for chemical warfare agents vapour sampling, the method is particularly useful in the process of verification of the Chemical Weapons Convention. PMID:24817348

Juillet, Y; Dubois, C; Bintein, F; Dissard, J; Bossée, A

2014-08-01

373

Fiber-assisted emulsification microextraction coupled with gas chromatography-mass spectrometry for the determination of aromatic amines in aqueous samples.  

PubMed

A novel fiber-assisted emulsification microextraction (FAEME) method was developed for the determination of eight aromatic amines (AAs) in aqueous samples. In this method, the extraction solvent (100 ?L chlorobenzene) and the dispersive material (1.0mg kapok fiber fragments) were added successively into the aqueous sample (5.0 mL), and then the mixture was emulsified by ultrasound to form the cloudy solution. Phase separation was performed by centrifugation, and the sedimented phase was transferred to micro-inserts with a microsyringe for analysis. All variables involved in the extraction process were identified and optimized. By coupling the analysis with gas chromatography-mass spectrometry (GC-MS), excellent detection limits (0.01-0.2 ?g L(-1)), good precision (RSDs, 3.33-6.56%) and linear ranges (0.10-160 ?g L(-1) and 1.0-160 ?g L(-1)) were obtained. Compared with the traditional solvent-emulsification method, the extraction recoveries of the proposed method were much higher. Satisfactory recoveries were achieved when the method was used for the analysis of AAs in spiked real water samples. PMID:25152494

Feng, Wen; Jiang, Ruifen; Chen, Bo; Ouyang, Gangfeng

2014-09-26

374

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

PubMed

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

Zhang, Mengliang; Harrington, Peter de B

2015-01-01

375

Determination of the alkylpyrazine composition of coffee using stable isotope dilution-gas chromatography-mass spectrometry (SIDA-GC-MS).  

PubMed

A stable isotope dilution analysis based on gas chromatography-mass spectrometry analysis (SIDA-GC-MS) was developed for the quantitative analysis of 12 alkylpyrazines found in commercially available coffee samples. These compounds contribute to coffee flavor. The accuracy of this method was tested by analyzing model mixtures of alkylpyrazines. Comparisons of alkylpyrazine-concentrations suggested that water as extraction solvent was superior to dichloromethane. The distribution patterns of alkylpyrazines in different roasted coffees were quite similar. The most abundant alkylpyrazine in each coffee sample was 2-methylpyrazine, followed by 2,6-dimethylpyrazine, 2,5-dimethylpyrazine, 2-ethylpyrazine, 2-ethyl-6-methylpyrazine, 2-ethyl-5-methylpyrazine, and 2,3,5-trimethylpyrazine, respectively. Among the alkylpyrazines tested, 2,3-dimethylpyrazine, 2-ethyl-3-methylpyrazine, 2-ethyl-3,6-dimethylpyrazine, and 2-ethyl-3,5-dimethylpyrazine revealed the lowest concentrations in roasted coffee. By the use of isotope dilution analysis, the total concentrations of alkylpyrazines in commercially available ground coffee ranged between 82.1 and 211.6 mg/kg, respectively. Decaffeinated coffee samples were found to contain lower amounts of alkylpyrazines than regular coffee samples by a factor of 0.3-0.7, which might be a result of the decaffeination procedure. PMID:23745606

Pickard, Stephanie; Becker, Irina; Merz, Karl-Heinz; Richling, Elke

2013-07-01

376

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

PubMed

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

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

2014-01-01

377

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

PubMed

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

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

2012-09-01

378

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

PubMed Central

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

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

2013-01-01

379

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

PubMed

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

Sereshti, Hassan; Heidari, Reza; Samadi, Soheila

2014-01-15

380

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

PubMed

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

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

2014-01-01

381

Use of thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) on identification of odorant emission focus by volatile organic compounds characterisation.  

PubMed

Volatile organic compounds (VOCs) from several different municipal solid wastes' treatment plants in Mallorca (Spain) have been analysed by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). Ambient (immission) air was collected during February and March 2011 by active sampling onto sorbents Tenax™ TA and Carboxen™ 1000. The study presents the chemical characterisation of 93 volatile organic compounds (VOCs) from an overall set of 84 immission air samples. 70 VOCs were positively identified. The linear fit for all 93 external standard calibration, from 10 mg L(-1) to 150 mg L(-1) (n=4), was within the range 0.974

Rodríguez-Navas, Carlos; Forteza, Rafael; Cerdà, Víctor

2012-11-01

382

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

PubMed

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

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

2009-12-01

383

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

PubMed

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

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

2015-05-01

384

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

PubMed

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

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

2015-02-13

385

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

2008-11-01

386

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

SciTech Connect

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

Arnts, R.R.

1985-01-01

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

2013-01-15

388

GC-MS in the analysis of organic compounds in meteorites. [Gas Chromatography-Mass Spectroscopy approaches  

NASA Technical Reports Server (NTRS)

The application of an analytical approach combining gas chromatography with mass spectrometry (GC-MS) has shown that the amino acid composition of meteorite extracts is quite complex. A computer was used in the evaluation of the data obtained in the investigations. The computer programs developed have been concerned solely with the mass spectra of amino acids. Specialized programs have been written to determine the number of carbon atoms in an amino acid which is a member of any of three subclasses.

Lawless, J. G.; Romiez, M. P.

1974-01-01

389

Radioimmunoassay and gas chromatography\\/mass spectrometry for a novel antiglaucoma medication of a prostaglandin derivative, S-1033, in plasma  

Microsoft Academic Search

A radioimmunoassay (RIA) and a gas chromatographic\\/mass spectrometric (GC\\/MS) method for a new antiglaucoma medicament, the prostaglandin derivative sodium (5Z,9?,11?,13E)-9,11-dihydroxyprosta-5,13-dienoate (S-1033), in human and rabbit plasma were investigated. For a competitive RIA, antisera from rabbit and radioiodine-labeled S-1033 were prepared by immunizing a conjugate of S-1033 with bovine serum albumin and by the Bolton and Hunter method, respectively. Pretreatment by

Goro Kominami; Masahiro Nakamura; Minoru Mizobuchi; Kyoko Ueki; Tomoko Kuroda; Akira Yamauchi; Shiro Takahashi

1996-01-01

390

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

PubMed

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

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

2014-08-01

391

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

PubMed Central

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

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

2014-01-01

392

Seeking organic compounds on Mars : in situ analysis of organic compounds by Gas Chromatography-Mass Spectrometry on MOMA experiment  

NASA Astrophysics Data System (ADS)

The search for signs of past or present life is one of the primary goals of future Mars exploratory missions. The Mars Organic Molecule Analyzer (MOMA) experiment of the ExoMars mission (set to launch 2016-2018) is a joint venture by the European Space Agency and NASA to develop a sensitive detector for organics on Mars. MOMA will be one of the main analytical instruments aboard the ExoMars Rover aimed at characterizing possible “signs-of-life molecules” in the Martian environment such as amino acids, carboxylic acids, nucleobases or polycyclic aromatic hydrocarbons (PAHs). With the aim to separate and detect organic compounds from Martian soil, the French MOMA team has built a gas chromatograph able to work in standalone mode by using a TCD detector. The gas chromatograph can also be coupled with an ion trap mass spectrometer developed by the US MOMA team. Moreover, a GC-MS compatible sample processing system (SPS) allowing the extraction and the chemical transformation of the organic compounds from the soil, that fits within space flight conditions, has also been developed. The sample processing is performed in an oven, dedicated to the MOMA experiment containing the solid sample (50-100mg). The internal temperature of oven can be ranged from 20 to 1000 °C which allows for pyrolysis, thermochemolysis or derivatization. The organic extraction step is achieved by using thermodesorption in the range of 100 to 300°C for 0.5 to 5 min. Then, the chemical derivatization and/or thermochemolysis of the extracted compounds is performed directly on the soil with a mixture of MTBSTFA-DMF, TMAH or DMF-DMA solution when enantiomeric separation is required. By decreasing the polarity of the target molecules, this step allows for their volatilization at a temperature below 250°C without any chemical degradation. Once derivatized, the volatile target molecules are trapped in a cold chemical trap and promptly desorbed into the gas chromatograph coupled to the mass spectrometer. Preliminary tests, performed on several analogue soils such as Atacama soil, with the MOMA SPS-GC/MS experiment demonstrated the capability to detect organic compounds such as amino and carboxylic acids with sensitivities below the ppm level.

Buch, A.; Freissinet, C.; Sternberg, R.; Pinnick, V.; Szopa, C.; Coll, P. J.; Rodier, C.; Garnier, C.; Steininger, H.; Moma Team

2010-12-01

393

Hydrocarbons identified in extracts from estuarine water accommodated no. 2 fuel oil by gas chromatography-mass spectrometry  

NASA Technical Reports Server (NTRS)

Results are presented on a computerized gas chromatograph-mass spectrometer analysis of methylene chloride and n-heptane extracts of a No. 2 fuel oil accommodated estuarine water sample. The analytical method is briefly described, and the limitations on the identifications are categorized. Some attempt was made to determine major and trace constituents in the water accommodate. Altogether 66 hydrocarbon compounds were identified specifically, and 75 compounds were partially identified. Seven compounds could be recognized as major constituents of the water accommodated oil and ten were present only as traces. The aromatic compounds found were alkyl benzenes, naphthalene, tetralin, indane, biphenyl, fluorene, anthracene, and some of their alkyl substituted isomers in the range of carbon numbers C7 to C15. Four n-alkanes, C10 to C13, were found along with four other assorted hydrocarbons.

Lewis, B. W.; Walker, A. L.; Bieri, R. H.

1974-01-01

394

Airborne measurements of sulfur dioxide, dimethyl sulfide, carbon disulfide, and carbonyl sulfide by isotope dilution gas chromatography/mass spectrometry  

NASA Technical Reports Server (NTRS)

A gas chromatograph/mass spectrometer is described for determining atmospheric sulfur dioxide, carbon disulfide, dimethyl sulfide, and carbonyl sulfide from aircraft and ship platforms. Isotopically labelled variants of each analyte were used as internal standards to achieve high precision. The lower limit of detection for each species for an integration time of 3 min was 1 pptv for sulfur dioxide and dimethyl sulfide and 0.2 pptv for carbon disulfide and carbonyl sulfide. All four species were simultaneously determined with a sample frequency of one sample per 6 min or greater. When only one or two species were determined, a frequency of one sample per 4 min was achieved. Because a calibration is included in each sample, no separate calibration sequence was needed. Instrument warmup was only a few minutes. The instrument was very robust in field deployments, requiring little maintenance.

Bandy, Alan R.; Thornton, Donald C.; Driedger, Arthur R., III

1993-01-01

395

Rapid screening of polar compounds in Brazilian propolis by high-temperature high-resolution gas chromatography-mass spectrometry.  

PubMed

Methanol extracts of propolis from six different places, five in Rio de Janeiro state and one in São Paulo state, both in the Southeast of Brazil, were investigated using high-temperature high-resolution gas chromatography (HT-HRGC) and HT-HRGC-mass spectometry. The main purpose of the study was to establish the applicability of HT-HRGC as an analytical method for systematic studies of polar propolis fractions. Several compounds, including carbohydrates, phenolic acid derivatives, and high molecular weight compounds (e.g., wax esters of long chain fatty alcohols) could be readily characterized in the crude extracts by HT-HRGC-MS. HT-HRGC and HT-HRGC-MS were shown to be quick and informative tools for rapid analysis of crude polar extracts without cleanup. PMID:11087464

Pereira, A S; Norsell, M; Cardoso, J N; Aquino Neto, F R; Ramos, M F

2000-11-01

396

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

USGS Publications Warehouse

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

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

2009-01-01

397

Sample Processing technique onboard ExoMars (MOMA) to analyze organic compounds by Gas Chromatography-Mass Spectrometry  

NASA Astrophysics Data System (ADS)

With the aim of separating and detecting organic compounds from Martian soil onboard the Mars Organic Molecule Analyzer (MOMA) experiment of the ExoMars 2018 upcoming joint ESA/NASA mission, we have developed three different space compatible sample preparation techniques compatible with space missions, able to extract and analyze by GC-MS a wide range of volatile and refractory compounds, including chirality analysis. Then, a sample processing utilizing three derivatization/extraction reactions has been carried out. The first reaction is based on a silyl reagent N-Methyl-N- (Tert-Butyldimethylsilyl)trifluoroacetamide (MTBSTFA) [1], the second one, N,N-Dimethylformamide Dimethylacetal (DMF-DMA) [2,3] is dedicated to the chirality detection and the third one is a thermochemolysis based on the use of tetramethylammoniumhydroxide (TMAH). The sample processing system is performed in an oven, dedicated to the MOMA experiment containing the solid sample (50-100mg). The internal temperature of the oven ranges from 20 to 900 °C. The extraction step is achieved by using thermodesorption in the range of 100 to 300°C for 5 to 20 min. Then, the chemical derivatization of the extracted compounds is performed directly on the soil sample by using a derivatyization capsule which contains a mixture of MTBSTFA-DMF or DMF-DMA solution when enantiomeric separation is required. By decreasing the polarity of the targeted molecules, this step allows their volatilization at a temperature below 250°C without any thermal degradation. Once derivatized, the volatile target molecules are trapped in a chemical trap and promptly desorbed into the gas chromatograph coupled to a mass spectrometer. Thermochemolysis is directly performed in the oven at 400°C during 5 min with a 25% (w/w) methanol solution of tetramethylammonium hydroxide (TMAH). Then, pyrolysis in the presence of TMAH allows both an efficient cleavage of polar bonds and the subsequent methylation of COOH, OH and NH2 groups, hence the release of less polar, GC-amenable compounds. By using thermochemolysis several families of biological molecules were detected such as fatty acids, n-alkenes and n-alkanols [4]. [1] A. Buch et al., Development of a gas chromatography compatible Sample Processing System (SPS) for the in-situ analysis of refractory organic matter in martian soil: preliminary result. Advances in Space Research 43, 143-151, 2009. [2] C. Freissinet et al., Journal of Chromatography A.1217 (5), 731-740, 2010. [3] U. Meierhenrich et al., Journal of Analytical and Applied Pyrolysis 60, 13-26, 2001. [4] C. Geffroy-Rodier et al., Journal of Analytical and Applied Pyrolysis, 85, 2009.

Buch, A.; Freissinet, C.; Sternberg, R.; Szopa, C.; Coll, P. J.; Brault, A.; Pinnick, V.; Siljeström, S.; Raulin, F.; Steininger, H.; Goesmann, F.; MOMA Team

2011-12-01

398

Detection of high molecular weight organic tracers in vegetation smoke samples by high-temperature gas chromatography-mass spectrometry  

SciTech Connect

High-temperature high-resolution gas chromatography (HTGC) is an established technique for the separation of complex mixtures of high molecular weight (HMW) compounds which do not elute when analyzed on conventional GC columns. The combination of this technique with mass spectrometry is not so common and application to aerosols is novel. The HTGC and HTGC-MS analyses of smoke samples taken by particle filtration from combustion of different species of plants provided the characterization of various classes of HMW compounds reported to occur for the first time in emissions from biomass burning. Among these components are a series of wax esters with up to 58 carbon numbers, aliphatic hydrocarbons, triglycerides, long chain methyl ketones, alkanols and a series of triterpenyl fatty acid esters which have been characterized as novel natural products. Long chain fatty acids with more than 32 carbon numbers are not present in the smoke samples analyzed. The HMW compounds in smoke samples from the burning of plants from Amazonia indicate the input of directly volatilized natural products in the original plants during their combustion. However, the major organic compounds extracted from smoke consist of a series of lower molecular weight polar components, which are not natural products but the result of the thermal breakdown of cellulose and lignin. In contrast, the HMW natural products may be suitable tracers for specific sources of vegetation combustion because they are emitted as particles without thermal alternation in the smoke and can thus be related directly to the original plant material.

Elias, V.O.; Simoneit, B.R.T. (Oregon State Univ., Corvallis, OR (United States)); Pereira, A.S.; Cardoso, J.N. (Univ. Federal do Rio de Janeiro (Brazil)); Cabral, J.A. (Inst. de Pesquisas da Amazonia, Amazonas (Brazil))

1999-07-15

399

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

PubMed Central

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

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

2014-01-01

400

The differentiation of fibre- and drug type Cannabis seedlings by gas chromatography/mass spectrometry and chemometric tools.  

PubMed

Cannabis cultivation in order to produce drugs is forbidden in Switzerland. Thus, law enforcement authorities regularly ask forensic laboratories to determinate cannabis plant's chemotype from seized material in order to ascertain that the plantation is legal or not. As required by the EU official analysis protocol the THC rate of cannabis is measured from the flowers at maturity. When laboratories are confronted to seedlings, they have to lead the plant to maturity, meaning a time consuming and costly procedure. This study investigated the discrimination of fibre type from drug type Cannabis seedlings by analysing the compounds found in their leaves and using chemometrics tools. 11 legal varieties allowed by the Swiss Federal Office for Agriculture and 13 illegal ones were greenhouse grown and analysed using a gas chromatograph interfaced with a mass spectrometer. Compounds that show high discrimination capabilities in the seedlings have been identified and a support vector machines (SVMs) analysis was used to classify the cannabis samples. The overall set of samples shows a classification rate above 99% with false positive rates less than 2%. This model allows then discrimination between fibre and drug type Cannabis at an early stage of growth. Therefore it is not necessary to wait plants' maturity to quantify their amount of THC in order to determine their chemotype. This procedure could be used for the control of legal (fibre type) and illegal (drug type) Cannabis production. PMID:20456880

Broséus, Julian; Anglada, Frédéric; Esseiva, Pierre

2010-07-15

401

Gas Chromatography-Mass Spectrometry-Based Metabolite Profiling of Salmonella enterica Serovar Typhimurium Differentiates between Biofilm and Planktonic Phenotypes.  

PubMed

The aim of this study was to utilize gas chromatography coupled with mass spectrometry (GC-MS) to compare and identify patterns of biochemical change between Salmonella cells grown in planktonic and biofilm phases and Salmonella biofilms of different ages. Our results showed a clear separation between planktonic and biofilm modes of growth. The majority of metabolites contributing to variance between planktonic and biofilm supernatants were identified as amino acids, including alanine, glutamic acid, glycine, and ornithine. Metabolites contributing to variance in intracellular profiles were identified as succinic acid, putrescine, pyroglutamic acid, and N-acetylglutamic acid. Principal-component analysis revealed no significant differences between the various ages of intracellular profiles, which would otherwise allow differentiation of biofilm cells on the basis of age. A shifting pattern across the score plot was illustrated when analyzing extracellular metabolites sampled from different days of biofilm growth, and amino acids were again identified as the metabolites contributing most to variance. An understanding of biofilm-specific metabolic responses to perturbations, especially antibiotics, can lead to the identification of novel drug targets and potential therapies for combating biofilm-associated diseases. We concluded that under the conditions of this study, GC-MS can be successfully applied as a high-throughput technique for "bottom-up" metabolomic biofilm research. PMID:25636852

Wong, Hui San; Maker, Garth L; Trengove, Robert D; O'Handley, Ryan M

2015-04-15

402

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

PubMed

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

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

2007-02-21

403

Simultaneous determination of HFBA-derivatized amphetamines and ketamines in urine by gas chromatography-mass spectrometry.  

PubMed

To facilitate the analysis of targeted drugs under high sample volume testing environment, an extraction, derivatization and gas chromatographic-mass spectrometric analysis method was developed for simultaneously determination of amphetamine (AMP), methamphetamine (MAMP), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyethylamphetamine (MDEA), ketamine, and norketamine in urine. This method utilized solid-phase extraction in conjunction with derivatization using heptafluorobutyric anhydride (HFBA) as the derivatization reagent. Using a 1-mL sample, the limits of quantitation achieved for the analysis of AMP, MAMP, MDA, MDMA, MDEA, ketamine, and norketamine were 25, 15, 60, 60, 70, 25, and 30 ng/mL, respectively. Upper limits of quantitation were 8000 ng/mL for all amphetamines and 6000 ng/mL for ketamine and norketamine. Except for dehydronorketamine (DHNK), within-day and between-day precisions (as expressed in CV%) for quality control samples were ? 3.1% and ? 4.95%, respectively. Except DHNK, the within-day accuracy ranged between 96.0% and 110.7% and the between-day accuracy ranged between 96.9% and 108.7%. A group of 107 urine samples previously determined to contain the target analytes were analyzed by this new approach. Quantitative data produced by both methods agreed well. With this new approach, we were able to use a single analytical protocol to conduct the confirmation test for samples that preliminarily tested positive (by immunoassay) for amphetamines, ketamine, or both. PMID:21439152

Lee, Hei Hwa; Lee, Jong Feng; Lin, Sin Yu; Chen, Ping Ho; Chen, Bai Hsiun

2011-04-01

404

Study of disulfide reduction and alkyl chloroformate derivatization of plasma sulfur amino acids using gas chromatography-mass spectrometry.  

PubMed

Four disulfide-reducing agents, dithiothreitol (DTT), 2,3-dimercaptopropanesulfonate (DMPS), and the newly tested 2-mercaptoethanesulfonate (MESNA) and Tris(hydroxypropyl)phosphine (THP), were investigated in detail for release of sulfur amino acids in human plasma. After protein precipitation with trichloroacetic acid (TCA), the plasma supernatant was treated with methyl, ethyl, or propyl chloroformate via the well-proven derivatization-extraction technique and the products were subjected to gas chromatographic-mass spectrometric (GC-MS) analysis. All the tested agents proved to be rapid and effective reducing agents for the assay of plasma thiols. When compared with DTT, the novel reducing agents DMPS, MESNA, and THP provided much cleaner extracts and improved analytical performance. Quantification of homocysteine, cysteine, and methionine was performed using their deuterated analogues, whereas other analytes were quantified by means of 4-chlorophenylalanine. Precise and reliable assay of all examined analytes was achieved, irrespective of the chloroformate reagent used. Average relative standard deviations at each analyte level were ?6%, quantification limits were 0.1-0.2 ?mol L(-1), recoveries were 94-121%, and linearity was over three orders of magnitude (r(2) equal to 0.997-0.998). Validation performed with the THP agent and propyl chloroformate derivatization demonstrated the robustness and reliability of this simple sample-preparation methodology. PMID:22349320

Svagera, Zden?k; Hanzlíková, Dagmar; Simek, Petr; Hušek, Petr

2012-03-01

405

Determination of homocysteine and its related compounds by solid-phase microextraction-gas chromatography-mass spectrometry.  

PubMed

The purpose of this study was to develop a simple and accurate analytical method to determine homocysteine (Hcy), cysteine (Cys), and methionine (Met) in aqueous samples. Until now, the most frequently used method for the assay of Hcy, Cys, and Met has been high-performance liquid chromatography with fluorescence detection after fluorescent tagging. The newly developed method involves the employment of the SPME (solid-phase microextraction) technique together with GC-MS. For application to a gas chromatographic system, alkyl formate derivatives were prepared in the form of N(O,S)-alkoxycarbonyl alkyl ester with the analytes in the aqueous samples. The optimum derivatizing regent for N(O,S)-alkoxycarbonyl alkyl ester was chosen by comparing the efficiency of the derivatized analytes in a GC through the SPME method and liquid-liquid extraction. The optimum conditions of the SPME system for the analytes derivatized with N(O,S)-ethoxycarbonyl propyl ester in the aqueous matrix were pH 3.0 and no salt, and 30 min equilibration time using an 85 microm PA (polyacrylate) fiber. The developed method is inexpensive, easy and rapid. PMID:10360416

Myung, S W; Kim, M; Min, H K; Yoo, E A; Kim, K R

1999-04-30

406

Determination of Tuta absoluta pheromones in water and tomato samples by headspace-gas chromatography-mass spectrometry.  

PubMed

Tuta absoluta is a tomato pest which is originally from South America. This pest was detected in eastern Spain in 2006 and it rapidly invaded various European countries and spread throughout the Mediterranean basin. The usual detection of this pest is based on the physical evaluation of the crops and in the exhaustive count of potential insects in dedicated traps. The early detection of that pest on the basis of more objective or measurable indicators is desirable. In this case, the combination of headspace and gas chromatography with mass spectrometric detection is proposed for the identification of Tuta absoluta pest using two of its pheromone components as markers. These components, namely: (3E,8Z,11Z)-tetradecatrien-1-yl acetate and (3E,8Z)-tetradecadien-1-yl acetate, are characteristic of Tuta absoluta and they are not present in other insect pheromones. The developed combination allows the determination of both components in water and tomato samples with limits of detection in the range from 25-32 ng/L to 89-111 ng/kg, respectively. The precision, expressed as relative standard deviation, was better than 4.6% for water samples and better than 7.1% when tomato samples were analyzed. The relative recovery values varied in the interval 94-100 and 83-99% for water and tomato samples. PMID:24928116

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

2015-01-01

407

Determination of emerging halogenated flame retardants and polybrominated diphenyl ethers in serum by gas chromatography mass spectrometry.  

PubMed

Emerging flame retardants are used in a great variety of household goods and thus have the potential to pollute our indoor environment. Health concerns regarding exposure to these flame retardants demand new methods to survey their occurrence in humans. This work describes development and optimization of an analytical method comprising solid phase extraction and gas chromatography coupled to mass spectrometry for the determination of besides 15 polybrominated diphenyl ethers, 7 emerging halogenated flame retardants in human serum (1,2-bis[2,4,6-tribromophenoxy] ethane, decabromodiphenyl ethane, hexabromobenzene, Dechlorane Plus(®), hexachlorocyclopentenyl-dibromocyclooctane, dechlorane 602 and 603). The method was thoroughly validated at three spiking levels obtaining averaged recoveries >80% with a RSD of 5% (n=12). Accuracies ranged from 88 to 125% except for DBDPE, which averaged 66% with overall RSD of 11% (n=12). Method limits of detection (MLD) ranged from 0.3 to 5.4 pg/mL serum, except for decabromodiphenyl ether and decabromodiphenyl ethane for which MLDs were 14 and 20 pg/mL serum, respectively. In human serum samples from Norway, we were able to detect and quantify hexabromobenzene, 1,2-bis[2,4,6-tribromophenoxy] ethane, Dechlorane Plus(®), Dechlorane 602 and 603. PMID:23992842

Cequier, Enrique; Marcé, Rosa Maria; Becher, Georg; Thomsen, Cathrine

2013-10-01

408

Nitrogen incorporation in Titan's tholins inferred by high resolution orbitrap mass spectrometry and gas chromatography-mass spectrometry  

NASA Astrophysics Data System (ADS)

Influx of solar photons and heavy charged particles from Saturn's magnetosphere on Titan's atmosphere - mainly comprised of methane and nitrogen - induce an intense organic photochemistry which leads to the formation of a large amount of aerosols in suspension in the atmosphere. In order to infer the role of nitrogen in aerosol formation processes we produced laboratory analogs of Titan's aerosols. In this work, we compare the composition of different analogs by using high resolution mass spectrometry and propose an additional study using gas-chromatography coupled to mass-spectrometry for a new kind of analog produced by polymerization of cryogenically trapped gaseous neutral species. The comparison of these materials emphasizes the importance of ion chemistry processes for the inclusion of nitrogen in molecules constituting Titan's tholins. A statistical approach is also used for the treatment of high resolution mass spectra of these highly complex organic materials. This method allows distinguishing molecular families that can be reconstructed by an ideal copolymer. We investigate several copolymer reconstructions, and we suggest that an HCN (or CH3CN)/C2H4 based copolymer agrees well with the polymeric structure of tholins produced with 5% of methane in nitrogen.

Gautier, Thomas; Carrasco, Nathalie; Schmitz-Afonso, Isabelle; Touboul, David; Szopa, Cyril; Buch, Arnaud; Pernot, Pascal

2014-10-01

409

Determination of organochlorine pesticides in sewage sludge by matrix solid-phase dispersion and gas chromatography-mass spectrometry.  

PubMed

A method based on matrix solid-phase dispersion (MSPD) has been developed for the determination of 16 organochlorine pesticides (OCs) in sludge from municipal sewage plants. Samples of lyophilized sludge were blended with alumina, placed in small columns and OCs extracted with dichloromethane assisted by sonication. Purification of the extracts was accomplished by solid-phase extraction on C(18) columns and OCs were eluted with acetonitrile. Analyses were performed by gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode (GC-MS-SIM) using deuterated OCs as internal standards. The limits of detection were between 0.03 ng/g for 4,4'-DDE and 0.7 ng/g for endrin aldehyde. Levels of OCs were determined in sewage sludge collected from 19 water treatment plants located in the province of Madrid (Spain). In all of the analyzed samples, aldrin was the compound most often found with a mean concentration of 76 ng/g. Endosulfan-I, alpha-BHC, 4,4'-DDE and 4,4'-DDT were also present at high concentrations, with average values ranging from 32.3 to 74.3 ng/g. OCs were detected in all of the samples, with a total concentration ranging from 52 to 528 ng/g dry weight. PMID:18371771

Sánchez-Brunete, Consuelo; Miguel, Esther; Tadeo, José L

2008-02-15

410

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

PubMed

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

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

2014-06-01

411

Application of solid-phase microextraction and gas chromatography-mass spectrometry for the determination of chlorophenols in leather.  

PubMed

This paper proposes a new analytical procedure based on the headspace solid-phase microextraction (HS-SPME) technique and gas chromatography-selected ion monitoring-mass spectrometry (GC-SIM-MS) for the determination of 16 phenols extracted from leather samples. The optimized conditions for the HS-SPME were obtained through two experimental designs - a two-level fractional factorial design followed by a central composite design - using the commercial SPME fiber polyacrylate 85??m (PA). The best extraction conditions were as follows: 200??L of derivatizing agent (acetic anhydride), 20?mL of saturated aqueous NaCl solution and extraction time and temperature of 50?min and 75°C, respectively. All optimized conditions were obtained with fixed leather sample mass (250?mg), vial volume (40?mL) and phosphate buffer pH (12) and concentration (50?mmol/L). Detection limits ranging from 0.03 to 0.20?ng/g, and relative standard deviation (RSD) lower than 10.23% (n=6) for a concentration of 800?ng/g (chlorophenols) and 1325?ng/g (2-phenylphenol) in the splitless mode were obtained. The recovery was studied at three concentration levels by adding different amounts of phenols to the leather sample and excellent recoveries ranging from 90.0 to 107.2% were obtained. The validated method was shown to be suitable for the quantification of phenols in leather samples, as it is simple, relatively fast and sensitive. PMID:22282421

de Souza Silveira, Cristine D; Martendal, Edmar; Soldi, Valdir; Carasek, Eduardo

2012-02-01

412

Determination of ultraviolet filters in water samples by vortex-assisted dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry.  

PubMed

For the first time, a simple solvent microextraction method termed vortex-assisted liquid-liquid microextraction (VADLLME) coupled with gas chromatography-mass spectrometry (GC-MS) has been developed and used for the analysis of six benzophenone ultraviolet (UV) filters (i.e. benzhydrol, 2,4-dihydroxybenzophenone, benzophenone, 2-hydroxy-4-methoxybenzophenone, ethylhexyl salicylate and homosalate) in water samples. The most favorable extraction variables in the VADLLME process were determined. In the extraction procedure, 40 ?L of tetrachloroethene as extraction solvent were directly injected into a 15-mL centrifuge tube containing 10 mL of aqueous sample, adjusted to pH 4 for VADLLME. After VADLLME, the extract was evaporated under a gentle nitrogen gas stream and then reconstituted with N,O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA), thus allowing the target analytes to be converted into their trimethylsilyl derivatives to optimize the GC-MS analysis. No centrifugation and disperser solvent were required in this microextraction procedure. Significantly, short extraction time and high extraction efficiency were achieved. This method opens up a potentially new horizon for on-site dispersive liquid-liquid microextraction. Under the optimum conditions, the proposed method provided good enrichment factors up to 310, with relative standard deviations ranging from 6.1 to 12.9%. The limits of quantification were in the range of 20-100 ng/L, depending on the analytes. The linearities were between 0.05 and 10 ?g/L and 0.1 and 10 ?g/L for different UV filters. Finally, the proposed method was successfully applied to the determination of UV filters from spiked genuine water samples and acceptable recoveries over the range of 71.0-120.0% were obtained. PMID:22749456

Zhang, Yufeng; Lee, Hian Kee

2012-08-01

413

Method development for the determination of wood preservatives in commercially treated wood using gas chromatography-mass spectrometry.  

PubMed

Fungicides and insecticides are commonly used preservatives to protect wood products against microbiological degradations. Currently, there is a lack of analytical methods addressing the quantitative determination of a wide range of wood preserving species in wood matrices. In this study, a reliable method was developed for the determination of a mixture of wood preserving agents with differing chemical structures (i.e., properties), including tebuconazole (TAZ), propiconazole (PAZ), 3-iodo-2-propynyl butylcarbamate (IPBC), and permethrin (PER), in pine wood. The analyte recoveries obtained by Soxhlet and multiple-stage sonication extractions were compared. While both extraction methods yielded similar results (80-100%), Soxhlet extraction was found to be less labor-intensive and thus preferred providing also lower RSDs of 1-6%. In comparison to methanol, commonly used as an extraction solvent for triazoles, acetone yielded similar extraction efficiencies for all analytes while reducing the time of sample concentration. The solid phase extraction method for triazoles was adapted to allow for a separation of IPBC and PER from the wood matrix. As opposed to previous studies, three recovery standards were employed, which enabled the correction of individual analyte losses during the sample preparation. The matrix-affected limits of detection (LODs) using gas chromatography with mass spectrometric detection were nearly the same for triazoles 0.07 and 0.21 ng g(-1) for PAZ and TAZ in sapwood and 0.18 and 0.21 ng g(-1) in heartwood, respectively. Higher LODs were observed for IPBC and PER: 3.9 and 1.7 ng g(-1) in sapwood, and 2.0 and 6.0 ng g(-1) in heartwood, respectively. The recoveries in the wood submitted to commercial sample treatment showed gradient distribution of analytes depending on the penetration of the treatment. PMID:21839199

Š?ávová, Jana; Sedgeman, Carl A; Smith, Zachary T; Frink, Lillian A; Hart, Jessica A; Niri, Vadoud H; Kubátová, Alena

2011-09-30

414

[Analysis of fatty acids in Gmnocypris przewalskii oil by gas chromatography/mass spectrometry with base-catalyzed transesterification].  

PubMed

The composition of fatty acids (FA) in Gymnocypris przewalskii oil was identified and quantified by gas chromatography (GC)/electron impact (EI) mass spectrometry (MS). A base-catalyzed transesterification method was used to convert fatty acids to methyl esters. The lipids were extracted using petroleum ether and the total lipids in dried meat and skin of Gymnocypris przewalskii were about 25%. Forty-seven fatty acids were identified in the current study. Main types of fatty acids found in the oils were normal saturated, mono-branched, multi-branched, cyclopropane, furanoid, normal monounsaturated and polyunsaturated fatty acids. Saturated fatty acids were approximately 25. 7% of the total, and the main components were C(14:0) (3.4%), C(16:0) (19.4%) and C(18:0) (1.1%). Unsaturated fatty acids were totally 73.6%, and the major components of monounsaturated fatty acids were C(16:1 (9)) (19.8%), C(18:1) (9)) (18. 6%) and C(18:1 (11)) (7.3%); polyunsaturated fatty acids were mainly composed of C(18:2 (9,12)) (4.8%), C(18:3 (9, 12, 15)) (3.1%), C(20:4 (5, 8, 1, 14)) (1.2%), C(20:5 (5, 8, 11, 14, 17)) (EPA, 9.4%) and C(22:6 (4, 7, 10, 13, 16, 19)) (DHA, 6.7%). Especially, furyl-, cyclopropane- and several odd and branched chain fatty acids were found in Gymnocypris przewalskii oil. It is thus an important dietary resource of functional fatty acids. PMID:16830471