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1

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

Treesearch

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

2

Targeted analysis of glycomics liquid chromatography\\/mass spectrometry data  

Microsoft Academic Search

Hydrophilic interaction chromatography (HILIC) liquid chromatography\\/mass spectrometry (LC\\/MS) is appropriate for all native\\u000a and reductively aminated glycan classes. HILIC carries the advantage that retention times vary predictably according to oligosaccharide\\u000a composition. Chromatographic conditions are compatible with sensitive and reproducible glycomics analysis of large numbers\\u000a of samples. The data are extremely useful for quantitative profiling of glycans expressed in biological tissues.

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

2011-01-01

3

Field gas chromatography-mass spectrometry for fast analysis.  

PubMed

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

Makas, Alexei L; Troshkov, Mikhail L

2004-02-01

4

Targeted analysis of glycomics liquid chromatography/mass spectrometry data.  

PubMed

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

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

2010-10-16

5

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

EPA Science Inventory

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

6

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

EPA Science Inventory

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

7

Serum xylose analysis by gas chromatography/mass spectrometry.  

PubMed

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

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

1994-11-01

8

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 ...

9

Applications of liquid chromatography-mass spectrometry for food analysis.  

PubMed

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

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

2012-04-17

10

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

Microsoft Academic Search

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

Thomas Moritz; Ana Maria Monteiro

1994-01-01

11

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

12

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

Microsoft Academic Search

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

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

1998-01-01

13

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

14

Analysis of antibiotics by liquid chromatography–mass spectrometry  

Microsoft Academic Search

The current status of the application of LC–MS in the analysis of antibiotic and antibacterial compounds is reviewed. The main application area of LC–MS in this field is the confirmation of identity in animal food products for human consumption at maximum residue levels, set by the regulatory authorities. LC–MS is found to play an important role in the determination and

W. M. A Niessen

1998-01-01

15

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

16

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

17

Matrix effects in quantitative pesticide analysis using liquid chromatography-mass spectrometry.  

PubMed

Combined liquid chromatography-mass spectrometry using electrospray or atmospheric-pressure chemical ionization has become an important tool in the quantitative analysis of pesticide residues in various matrices in relation to environmental analysis, food safety, and biological exposure monitoring. One of the major problems in the quantitative analysis using LC-MS is that compound and matrix-dependent response suppression or enhancement may occur, the so-called matrix effect. This article reviews issues related to matrix effects, focusing on quantitative pesticide analysis, but also paying attention to expertise with respect to matrix effects acquired in other application areas of LC-MS, especially quantitative bioanalysis in the course of drug development. PMID:16783795

Niessen, W M A; Manini, P; Andreoli, R

18

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

PubMed

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

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

1980-03-01

19

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

PubMed

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

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

2005-12-27

20

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

PubMed

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

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

2008-09-08

21

Liquid chromatography/mass spectrometry  

SciTech Connect

The combination of high-performance liquid chromatography (HPLC) and mass spectrometry (MS) offers the analytical chemist one of the most powerful analytical techniques of modern times. Both techniques have matured to the point that they represent two of the most important tools available for the characterization of organic compounds. Unfortunately, coupling these techniques (LC/MS) has been a more challenging task than it was for gas chromatography/mass spectrometry (GC/MS). The potential benefits derived from on-line coupling of LC to MS have been known for about 12 years. The problems associated with interfacing these two techniques in a practical way are considerable, but recently there has been significant progress toward this end. An excellent review covering the status of this subject through 1978 appeared in this journal, and this article will attempt to cover the state of the art through early 1986. As with any rapidly developing area, the details of all aspects of LC/MS cannot be covered in a short overview. The reader may refer to the references and recent reviews more information on other aspects of this subject.

Covey, T.R.; Lee, E.D.; Bruins, A.P.; Henion, J.D.

1986-12-01

22

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

23

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

SciTech Connect

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

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

1994-08-01

24

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...

25

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

26

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

27

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

Microsoft Academic Search

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

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

28

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

PubMed

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

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

2012-02-01

29

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

PubMed

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

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

2013-01-22

30

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

PubMed

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

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

2012-12-03

31

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

PubMed

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

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

2013-07-26

32

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

PubMed

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

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

1998-07-31

33

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

SciTech Connect

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

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

1992-10-01

34

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

SciTech Connect

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

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

1983-02-01

35

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

PubMed

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

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

2006-10-01

36

Linker-assisted immunoassay and liquid chromatography/mass spectrometry for the analysis of glyphosate  

USGS Publications Warehouse

A novel, sensitive, linker-assisted enzyme-linked immunosorbent assay (L'ELISA) was compared to on-line solidphase extraction (SPE) with high-performance liquid chromatography/mass spectrometry (HPLC/MS) for the analysis of glyphosate in surface water and groundwater samples. The L'ELISA used succinic anhydride to derivatize glyphosate, which mimics the epitotic attachment of glyphosate to horseradish peroxidase hapten. Thus, L'ELISA recognized the derivatized glyphosate more effectively (detection limit of 0.1 ??g/L) and with increased sensitivity (10-100 times) over conventional ELISA and showed the potential for other applications. The precision and accuracy of L'ELISA then was compared with on-line SPE/HPLC/MS, which detected glyphosate and its degradate derivatized with 9-fluorenylmethyl chloroformate using negative-ion electrospray (detection limit 0.1 ??g/L, relative standard deviation ??15%). Derivatization efficiency and matrix effects were minimized by adding an isotope-labeled glyphosate (2-13C15N). The accuracy of L'ELISA gave a false positive rate of 18% between 0.1 and 1.0 ??g/L and a false positive rate of only 1% above 1.0 ??g/L. The relative standard deviation was ??20%. The correlation of L'ELISA and HPLC/MS for 66 surface water and groundwater samples was 0.97 with a slope of 1.28, with many detections of glyphosate and its degradate in surface water but not in groundwater.

Lee, E. A.; Zimmerman, L. R.; Bhullar, B. S.; Thurman, E. M.

2002-01-01

37

Correlation between peak capacity and protein sequence coverage in proteomics analysis by liquid chromatography-mass spectrometry\\/mass spectrometry  

Microsoft Academic Search

Liquid chromatography-mass spectrometry\\/mass spectrometry (LC-MS\\/MS) allows the acquisition of a vast amount of analytical data in the aim of identifying peptides and proteins. Difficulties arise when attempting to identify proteins from the results of analyses of their peptide digests. We investigated possible quantitative correlations between the peak capacity achieved in chromatographic analyses and the protein sequence coverage. For this purpose,

Jacob N. Fairchild; Matthew J. Walworth; Krisztián Horváth; Georges Guiochon

2010-01-01

38

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

PubMed

The fouling from the different sections of the cracked gas compressor in Daqing Petrochemical Corporation was analyzed by pyrolysis gas chromatography-mass spectrometry (Py/GC-MS). All the samples were cracked in RJ-1 tube furnace cracker at the cracking temperature of 500 degrees C, and separated with a 60 m DB-1 capillary column. An electron impact ionization (EI) source was used with the ionizing voltage of 70 eV. The results showed the formation of fouling was closely related with cyclopentadiene which accounted for about 50% of the cracking products. Other components detected were 1-butylene, propylene, methane and n-butane. This Py/GC-MS method can be used as an effective approach to analyze the causes of fouling in the petrochemical plants. PMID:24063202

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

2013-06-01

39

Direct Analysis of Rat Bile for Acetaminophen and Two of Its Conjugated Metabolites via Thermospray Liquid Chromatography/Mass Spectrometry.  

National Technical Information Service (NTIS)

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

L. D. Betowski W. A. Korfmacher J. O. Lay D. W. Potter J. A. Hinson

1987-01-01

40

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

EPA Science Inventory

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

41

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

SciTech Connect

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

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

1980-09-01

42

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

PubMed

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

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

2005-10-19

43

Multiclass mycotoxin analysis in food, environmental and biological matrices with chromatography/mass spectrometry.  

PubMed

Mold metabolites that can elicit deleterious effects on other organisms are classified as mycotoxins. Human exposure to mycotoxins occurs mostly through the intake of contaminated agricultural products or residues due to carry over or metabolite products in foods of animal origin such as milk and eggs, but can also occur by dermal contact and inhalation. Mycotoxins contained in moldy foods, but also in damp interiors, can cause diseases in humans and animals. Nephropathy, various types of cancer, alimentary toxic aleukia, hepatic diseases, various hemorrhagic syndromes, and immune and neurological disorders are the most common diseases that can be related to mycotoxicosis. The absence or presence of mold infestation and its propagation are seldom correlated with mycotoxin presence. Mycotoxins must be determined directly, and suitable analytical methods are necessary. Hundreds of mycotoxins have been recognized, but only for a few of them, and in a restricted number of utilities, a maximum acceptable level has been regulated by law. However, mycotoxins seldom develop alone; more often various types and/or classes form in the same substrate. The co-occurrence might render the individual mycotoxin tolerance dose irrelevant, and therefore the mere presence of multiple mycotoxins should be considered a risk factor. The advantage of chromatography/mass spectrometry (MS) is that many compounds can be determined and confirmed in one analysis. This review illustrates the state-of-the-art of mycotoxin MS-based analytical methods for multiclass, multianalyte determination in all the matrices in which they appear. A chapter is devoted to the history of the long-standing coexistence and interaction among humans, domestic animals and mycotoxicosis, and the history of the discovery of mycotoxins. Quality assurance, although this topic relates to analytical chemistry in general, has been also examined for mycotoxin analysis as a preliminary to the systematic literature excursus. Sample handling is a crucial step to devise a multiclass analytical method; so when possible, it has been treated separately for a better comparison before tackling the instrumental part of the whole analytical method. This structure has resulted sometimes in unavoidable redundancies, because it was also important to underline the interconnection. Most reviews do not deal with all the possible mycotoxin sources, including the environmental ones. The focus of this review is the analytical methods based on MS for multimycotoxin class determination. Because the final purpose to devise multimycotoxin analysis should be the assessment of the danger to health of exposition to multitoxicants of natural origin (and possibly also the interaction with anthropogenic contaminants), therefore also the analytical methods for environmental relevant mycotoxins have been thoroughly reviewed. Finally, because the best way to shed light on actual risk assessment could be the individuation of exposure biomarkers, the review covers also the scarce literature on biological fluids. PMID:22065561

Capriotti, Anna Laura; Caruso, Giuseppe; Cavaliere, Chiara; Foglia, Patrizia; Samperi, Roberto; Laganà, Aldo

2011-11-07

44

Liquid chromatography\\/mass spectrometry  

Microsoft Academic Search

The combination of high-performance liquid chromatography (HPLC) and mass spectrometry (MS) offers the analytical chemist one of the most powerful analytical techniques of modern times. Both techniques have matured to the point that they represent two of the most important tools available for the characterization of organic compounds. Unfortunately, coupling these techniques (LC\\/MS) has been a more challenging task than

Thomas R. Covey; Edgar D. Lee; Andries P. Bruins; Jack D. Henion

1986-01-01

45

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

PubMed

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

Koo, Imhoi; Kim, Seongho; Zhang, Xiang

2013-05-13

46

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

PubMed

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

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

2007-07-24

47

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

PubMed

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

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

2011-10-29

48

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

PubMed

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

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

2009-05-21

49

Recent advances on multidimensional liquid chromatography-mass spectrometry for proteomics: from qualitative to quantitative analysis--a review.  

PubMed

With the acceleration of proteome research, increasing attention has been paid to multidimensional liquid chromatography-mass spectrometry (MDLC-MS) due to its high peak capacity and separation efficiency. Recently, many efforts have been put to improve MDLC-based strategies including "top-down" and "bottom-up" to enable highly sensitive qualitative and quantitative analysis of proteins, as well as accelerate the whole analytical procedure. Integrated platforms with combination of sample pretreatment, multidimensional separations and identification were also developed to achieve high throughput and sensitive detection of proteomes, facilitating highly accurate and reproducible quantification. This review summarized the recent advances of such techniques and their applications in qualitative and quantitative analysis of proteomes. PMID:22652259

Wu, Qi; Yuan, Huiming; Zhang, Lihua; Zhang, Yukui

2012-04-21

50

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

PubMed

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

Sarkissian, Garry

2007-09-01

51

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

Microsoft Academic Search

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

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

2005-01-01

52

Rapid analysis of pentazocine in human plasma by liquid chromatography\\/mass spectrometry with sonic spray ionization  

Microsoft Academic Search

A rapid determination method for pentazocine in human plasma without complicated pretreatments has been constructed by liquid chromatography\\/mass spectrometry (LC\\/MS) with sonic spray ionization (SSI) using an Oasis HLB cartridge column. The reliability on our method was investigated for human plasma samples spiked with pentazocine and dextromethorphan as internal standard. The regression equation for pentazocine showed good linearity in the

Tetsuya Arinobu; Hideki Hattori; Akira Ishii; Takeshi Kumazawa; Xiao-Pen Lee; Sadao Kojima; Osamu Suzuki; Hiroshi Seno

2003-01-01

53

Matrix effects in pesticide multi-residue analysis by liquid chromatography–mass spectrometry  

Microsoft Academic Search

Three sample preparation methods: Luke method (AOAC 985.22), QuEChERS (quick, easy, cheap, effective, rugged and safe) and matrix solid-phase dispersion (MSPD) were applied to different fruits and vegetables for analysis of 14 pesticide residues by high-performance liquid chromatography with electrospray ionization–mass spectrometry (HPLC\\/ESI\\/MS). Matrix effect, recovery and process efficiency of the sample preparation methods applied to different fruits and vegetables

Anneli Kruve; Allan Künnapas; Koit Herodes; Ivo Leito

2008-01-01

54

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

Microsoft Academic Search

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

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

2006-01-01

55

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

56

[Development of on-line sample preparation coupled with liquid chromatography-mass spectrometry for analysis of small molecules in biofluids].  

PubMed

On-line liquid chromatography-mass spectrometry (LC-MS) is a highly sensitive, highly selective and high throughput method for the analysis of small molecules in biofluids. The developments, characterizations and applications of pre-column, on-line LC-MS method and its configuration in the recent five years are reviewed. PMID:18161313

Liu, Min; Zhao, Lixia; Guo, Baoyuan; Lin, Jin-Ming

2007-09-01

57

Routine application using single quadrupole liquid chromatography-mass spectrometry to pesticides analysis in citrus fruits.  

PubMed

A rapid and sensitive liquid chromatography-electrospray ionization-mass spectrometry method has been developed for the routine analysis of buprofezin, bupirimate, hexaflumuron, tebufenpyrad, fluvalinate and pyriproxyfen in citrus fruits. Extracts were obtained by matrix solid-phase dispersion (MSPD) using C18 as dispersant and dichloromethane-methanol (80:20, v/v) as eluent. Matrix effects were tested for all matrices by addition of standard to sample blank extracts (samples containing no detectable residues). Mean recoveries obtained at fortification levels between 0.01 and 5 mg kg(-1) were 57-97% with relative standard deviations (RSDs) from 5 to 19%. The limits of quantification (LOQ) were in the range of 0.01-0.2 mg kg(-1) and lower than maximum residue limits (MRLs) established by the Spanish legislation. The MSPD was compared with conventional ethyl acetate extraction, showing equivalent recoveries and precision. Although the sample is more concentrated (5-fold) by solid-liquid extraction (SLE) with ethyl acetate than by MSPD, LOQs obtained by both techniques, were almost equal, because MSPD reduces matrix effects, baseline noise, and interfering peaks from the matrix. The proposed method has been applied to the determination of selected pesticides in real samples. Liquid chromatography-tandem mass spectrometry (LC-MS-MS) with quadrupole ion trap (QIT) and triple quadrupole (TQ) have been used as confirmatory tool for positive samples according to a recent No. SANCO/10476/2003 European Union Guideline. PMID:16130755

Soler, Carla; Mañes, Jordi; Picó, Yolanda

2005-09-23

58

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

PubMed Central

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

2013-01-01

59

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

PubMed Central

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

He, Jun; Shamsi, Shahab A.

2009-01-01

60

Analysis of macrolide antibiotics in river water by solid-phase extraction and liquid chromatography–mass spectrometry  

Microsoft Academic Search

A liquid chromatography–mass spectrometry (LC–MS) method was developed for the determination of five macrolides in natural water samples, using kitasamycin as surrogate. The macrolides were extracted from water samples using Oasis HLB cartridges. Pre-concentration factors up to 250 were obtained. Separation was carried out in an end-capped silica-based C18 column and mobile phases consisting of water\\/acetonitrile mixtures containing ammonium acetate.

Sònia Abuin; Rosa Codony; Ramon Compañó; Mercè Granados; Maria Dolors Prat

2006-01-01

61

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

Microsoft Academic Search

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

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

2007-01-01

62

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

Microsoft Academic Search

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

Carolyn M Sandison; Robert Alexander; Robert I Kagi

2003-01-01

63

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

PubMed

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

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

2010-09-30

64

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

PubMed

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

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

2000-07-01

65

The Application of Chromatography-Mass Spectrometry: Methods to Metabonomics  

Microsoft Academic Search

The widespread availability, suitability, and high sensitivity of chromatography-mass spectrometry for chemical profiling\\u000a analysis of multi-component biosamples are demonstrated by the comprehensive analysis of metabolites in all kind of biofluids\\u000a or tissue and cell extracts. This review provides an overview of current chromatographic-mass spectrometric metabonomic methods\\u000a and applications. The focus is on the description of global metabolic profiling techniques as

Zeming Wu; Zhiqiang Huang; Rainer Lehmann; Chunxia Zhao; Guowang Xu

2009-01-01

66

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

PubMed

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

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

2010-12-28

67

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

PubMed

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

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

2011-08-04

68

Cellular lipid extraction for targeted stable isotope dilution liquid chromatography-mass spectrometry analysis.  

PubMed

The metabolism of fatty acids, such as arachidonic acid (AA) and linoleic acid (LA), results in the formation of oxidized bioactive lipids, including numerous stereoisomers(1,2). These metabolites can be formed from free or esterified fatty acids. Many of these oxidized metabolites have biological activity and have been implicated in various diseases including cardiovascular and neurodegenerative diseases, asthma, and cancer(3-7). Oxidized bioactive lipids can be formed enzymatically or by reactive oxygen species (ROS). Enzymes that metabolize fatty acids include cyclooxygenase (COX), lipoxygenase (LO), and cytochromes P450 (CYPs)(1,8). Enzymatic metabolism results in enantioselective formation whereas ROS oxidation results in the racemic formation of products. While this protocol focuses primarily on the analysis of AA- and some LA-derived bioactive metabolites; it could be easily applied to metabolites of other fatty acids. Bioactive lipids are extracted from cell lysate or media using liquid-liquid (l-l) extraction. At the beginning of the l-l extraction process, stable isotope internal standards are added to account for errors during sample preparation. Stable isotope dilution (SID) also accounts for any differences, such as ion suppression, that metabolites may experience during the mass spectrometry (MS) analysis(9). After the extraction, derivatization with an electron capture (EC) reagent, pentafluorylbenzyl bromide (PFB) is employed to increase detection sensitivity(10,11). Multiple reaction monitoring (MRM) is used to increase the selectivity of the MS analysis. Before MS analysis, lipids are separated using chiral normal phase high performance liquid chromatography (HPLC). The HPLC conditions are optimized to separate the enantiomers and various stereoisomers of the monitored lipids(12). This specific LC-MS method monitors prostaglandins (PGs), isoprostanes (isoPs), hydroxyeicosatetraenoic acids (HETEs), hydroxyoctadecadienoic acids (HODEs), oxoeicosatetraenoic acids (oxoETEs) and oxooctadecadienoic acids (oxoODEs); however, the HPLC and MS parameters can be optimized to include any fatty acid metabolites(13). Most of the currently available bioanalytical methods do not take into account the separate quantification of enantiomers. This is extremely important when trying to deduce whether or not the metabolites were formed enzymatically or by ROS. Additionally, the ratios of the enantiomers may provide evidence for a specific enzymatic pathway of formation. The use of SID allows for accurate quantification of metabolites and accounts for any sample loss during preparation as well as the differences experienced during ionization. Using the PFB electron capture reagent increases the sensitivity of detection by two orders of magnitude over conventional APCI methods. Overall, this method, SID-LC-EC-atmospheric pressure chemical ionization APCI-MRM/MS, is one of the most sensitive, selective, and accurate methods of quantification for bioactive lipids. PMID:22127066

Gelhaus, Stacy L; Mesaros, A Clementina; Blair, Ian A

2011-11-17

69

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

PubMed

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

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

2011-12-10

70

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

PubMed

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

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

71

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

PubMed

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

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

2012-07-20

72

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

73

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

PubMed

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

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

2007-12-24

74

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

PubMed

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

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

2007-04-04

75

ANALYSIS OF HOUSTON AEROSOL SAMPLES BY GC/MS (GAS CHROMATOGRAPHY-MASS SPECTROMETRY) METHODS  

EPA Science Inventory

An analysis procedure developed to give a qualitative and quantitative analysis for organic compounds adsorbed on aerosols collected by Hi-Vol filters was adapted and applied to a similar analysis of aerosols collected by dichotomous filters. Analysis was conducted for five dicho...

76

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

Microsoft Academic Search

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

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

2003-01-01

77

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

78

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

79

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

Microsoft Academic Search

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

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

2009-01-01

80

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

Microsoft Academic Search

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

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

1996-01-01

81

The mechanism of adenosine to inosine conversion by the double-stranded RNA unwinding\\/modifying activity: A high-performance liquid chromatography-mass spectrometry analysis  

Microsoft Academic Search

The authors have used directly combined high-performance liquid chromatography-mass spectrometry (LC\\/MS) to examine the mechanism of the reaction catalyzed by the double-stranded RNA unwinding\\/modifying activity. A double-stranded RNA substrate in which all adenosines were uniformly labeled with ¹³C was synthesized. An LC\\/MS analysis of the nucleoside products from the modified, labeled substrate confirmed that adenosine is modified to inosine during

Andrew G. Polson; Pamela F. Crain; Steven C. Pomerantz; James A. McCloskey; Brenda L. Bass

1991-01-01

82

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...

83

Analysis of badger urine volatiles using gas chromatography-mass spectrometry and pattern recognition techniques.  

PubMed

The potential for badger urine to signal olfactory information relating to sex, age class and seasonality was investigated by performing GCMS headspace analysis followed by pattern recognition statistical analysis on 84 urine samples collected from different categories of animal. Approximately 300 compounds were identified using library searching, and GCMS peak areas were recorded for the 33 most common. PCA was performed on the normalised and standardised data from all badgers, through which significant seasonal trends and groupings of homologous series of compounds were detected. PCA was also performed on the three subgroups of adults in the spring, summer and autumn, and a level of sexual discrimination was possible during the latter two seasons. Malanobis distances on the scores of the first five principal components provided good discrimination for these three subgroups, but discrimination was poor when all samples were analysed together. This, combined with the initial results of the PCA, confirms that a strong seasonal trend is imposed upon the sexual trend in this dataset. Our initial analysis indicates that badger urine potentially contains olfactory cues relating to sex and season. The relevance of these findings to understanding olfactory communication in mammals is discussed. PMID:11394302

Service, K M; Brereton, R G; Harris, S

2001-05-01

84

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

SciTech Connect

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

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

2010-04-15

85

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

86

Dried blood spots: liquid chromatography-mass spectrometry analysis of ?9-tetrahydrocannabinol and its main metabolites.  

PubMed

A sensitive and selective HPLC-MS/MS method has been developed for the first time for the analysis of ?(9)-tetrahydrocannabinol (the most important active cannabinoid) and its hydroxylated and carboxylated metabolites in human Dried Blood Spots (DBSs). The simultaneous determination of ?(9)-tetrahydrocannabinol and its two main metabolites allows assessing the time elapsed after the drug intake and distinguishing between acute or former consumption. This is an important information in specific contexts such as "on street" controls by police forces. DBSs have been chosen as the optimal biological matrix for this kind of testing, since they provide information on the actual state of intoxication, without storage and transportation problems usually associated with classical blood testing. The analysis is carried out on a C8 reversed phase column with a mobile phase composed of 0.1% formic acid in a water/methanol mixture and an electrospray ionisation (ESI) source, coupled to a triple quadrupole mass spectrometer. The method was validated according to international guidelines, with satisfactory results in terms of extraction yields, precision, stability and accuracy. Application to real DBS samples from Cannabis abusers gave reliable results, thus confirming the methodology suitability for roadside testing. PMID:23228918

Mercolini, Laura; Mandrioli, Roberto; Sorella, Vittorio; Somaini, Lorenzo; Giocondi, Daniele; Serpelloni, Giovanni; Raggi, Maria Augusta

2012-11-19

87

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

PubMed

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

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

2012-10-23

88

Liquid chromatography-mass spectrometry-based metabolomic analysis of livers from aged rats.  

PubMed

We used UPLC-Q-TOF MS to analyze hepatic metabolites of rats aged 6, 12, 18, and 24 months; the MS data were processed by partial least-squares discriminant analysis (PLS-DA) to investigate the discrimination among sample groups. Rats were significantly separated with increasing age, except those aged between 6 and 12 months. We identified only 25 of 120 metabolites contributing to the separation: lipid metabolites (glycerol-3-phosphate, linolenic acid, lysophosphatidylcholines [lysoPCs]), energy metabolism intermediates (betaine, carnitine, acylcarnitines, creatine, pantothenic acid), nucleic acid metabolites (inosine, xanthosine, uracil, hypoxanthine, xanthine), and tyrosine. Aging accumulated energy metabolism intermediates, hypoxanthine, xanthine, and 2 major lysoPCs (C18:0 and C22:6). The NAD level and NAD/NADH ratio decreased with age. It was indicated that aging might decrease energy production through ?-oxidation because of a decrease in NAD despite the accumulation of lipid energy metabolism intermediates. In addition to energy dysregulation, hypoxanthine and xanthine, which are elevated with age, might accumulate reactive oxygen species in the liver. These results strongly support two aging theories: those of energy dysregulation and free radicals. Additionally, we propose a metabolic pathway related to aging based on these hepatic metabolites. These metabolites and the proposed aging pathway could be used to understand aging and related diseases better, and increase the predictability of aging risk. PMID:22380686

Son, Nari; Hur, Haeng Jeon; Sung, Mi Jeong; Kim, Myung-Sunny; Hwang, Jin-Taek; Park, Jae Ho; Yang, Hye Jeong; Kwon, Dae Young; Yoon, Suk Hoo; Chung, Hae Young; Kim, Hyun-Jin

2012-03-15

89

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

PubMed

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

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

2013-01-03

90

Gas Chromatography-Mass Spectrometry Experiment  

NSDL National Science Digital Library

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

Solow, Mike

2013-07-19

91

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

PubMed

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

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

2010-07-22

92

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

Microsoft Academic Search

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

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

2007-01-01

93

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

PubMed

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

Durden, D A; Boulton, A A

1988-05-25

94

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

PubMed

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

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

2004-09-22

95

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

96

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

97

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

98

Analysis of macrolide antibiotics in river water by solid-phase extraction and liquid chromatography-mass spectrometry.  

PubMed

A liquid chromatography-mass spectrometry (LC-MS) method was developed for the determination of five macrolides in natural water samples, using kitasamycin as surrogate. The macrolides were extracted from water samples using Oasis HLB cartridges. Pre-concentration factors up to 250 were obtained. Separation was carried out in an end-capped silica-based C18 column and mobile phases consisting of water/acetonitrile mixtures containing ammonium acetate. Detection was performed by mass spectrometry with a single quadrupole and a triple quadrupole using an electrospray interface. The quality parameters obtained with these two approaches were compared. The detection limits of the whole process were about 1 ng l(-1). The recoveries from 250 ml of water samples spiked at 25-125 ng l(-1) level were in the range 85-115%, except for azithromycin levels, which were around 70%. Erythromycin-H2O, clarithromycin and azithromyzin were found, at the sub ng l(-1) level, in the studied rivers. PMID:16515792

Abuin, Sònia; Codony, Rosa; Compañó, Ramon; Granados, Mercè; Prat, Maria Dolors

2006-03-03

99

Overcoming matrix effects in liquid chromatography-mass spectrometry.  

PubMed

A major limitation in quantitative analysis with electrospray ionization mass spectrometry (ESI-MS) is represented by the so-called matrix effects in which the matrix coextracted with the analytes can alter the signal response, causing either suppression or enhancement, resulting in poor analytical accuracy, linearity, and reproducibility. In the direct electron ionization liquid chromatography-mass spectrometry (direct-EI LC-MS) interface the ionization process is based on electron impact ionization, and it occurs in the gas phase and is not influenced by coeluted matrix compounds. In this work we quantitatively evaluated matrix effects on enriched environmental and biological samples, with different extraction procedures, using ESI and direct-EI LC-MS. As expected, the samples analyzed with direct-EI were not affected by matrix composition, whereas with ESI we observed either signal suppression or enhancement, depending on the sample nature. PMID:19551950

Cappiello, Achille; Famiglini, Giorgio; Palma, Pierangela; Pierini, Elisabetta; Termopoli, Veronica; Trufelli, Helga

2008-12-01

100

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

PubMed

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

Yu, Yong; Wu, Laosheng

2011-12-17

101

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

PubMed

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

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

2013-06-28

102

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

PubMed

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

Wu, Yaoxing; Chang, Victor W-C

2012-03-23

103

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

NASA Astrophysics Data System (ADS)

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

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

104

Rapid chemical profiling of saponins in the flower buds of Panax notoginseng by integrating MCI gel column chromatography and liquid chromatography/mass spectrometry analysis.  

PubMed

The flower buds of Panax notoginseng (Notoginseng flower, FBP) are used as the traditional Chinese medicine San-Qi-Hua. In this study, we conducted column chromatography fractionation and liquid chromatography/mass spectrometry (LC/MS) analysis to comprehensively profile bioactive notoginseng saponins (ginsenosides) in FBP. MCI gel column chromatography allowed separation and enrichment of minor saponins. Electrospray ionization tandem mass spectrometry of [M-H](-) and [M+Na](+) precursor ions of the saponins provided reliable structural information for the sapogenin, and sequence of sugar chains. Confirmed by high-accuracy Q-TOF analysis, 170 notoginseng saponins were characterized from FBP, and 91 of them were reported from Panax species for the first time. The new ginsenosides contain acyl groups on ?-chain, malonyl group at 20-OH, or di-malonyl groups. This study also indicated that the flower buds of P. notoginseng contained more protopanaxadiol-type but less protopanaxatriol-type ginsenosides than the roots. PMID:23561171

Yang, Wen-Zhi; Bo, Tao; Ji, Shuai; Qiao, Xue; Guo, De-An; Ye, Min

2013-01-30

105

Pathway Confirmation and Flux Analysis of Central Metabolic Pathways in Desulfovibrio vulgaris Hildenborough using Gas Chromatography-Mass Spectrometry and Fourier Transform-Ion Cyclotron Resonance Mass Spectrometry? †  

PubMed Central

Flux distribution in central metabolic pathways of Desulfovibrio vulgaris Hildenborough was examined using 13C tracer experiments. Consistent with the current genome annotation and independent evidence from enzyme activity assays, the isotopomer results from both gas chromatography-mass spectrometry (GC-MS) and Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) indicate the lack of an oxidatively functional tricarboxylic acid (TCA) cycle and an incomplete pentose phosphate pathway. Results from this study suggest that fluxes through both pathways are limited to biosynthesis. The data also indicate that >80% of the lactate was converted to acetate and that the reactions involved are the primary route of energy production [NAD(P)H and ATP production]. Independently of the TCA cycle, direct cleavage of acetyl coenzyme A to CO and 5,10-methyl tetrahydrofuran also leads to production of NADH and ATP. Although the genome annotation implicates a ferredoxin-dependent oxoglutarate synthase, isotopic evidence does not support flux through this reaction in either the oxidative or the reductive mode; therefore, the TCA cycle is incomplete. FT-ICR MS was used to locate the labeled carbon distribution in aspartate and glutamate and confirmed the presence of an atypical enzyme for citrate formation suggested in previous reports [the citrate synthesized by this enzyme is the isotopic antipode of the citrate synthesized by the (S)-citrate synthase]. These findings enable a better understanding of the relation between genome annotation and actual metabolic pathways in D. vulgaris and also demonstrate that FT-ICR MS is a powerful tool for isotopomer analysis, overcoming the problems with both GC-MS and nuclear magnetic resonance spectroscopy.

Tang, Yinjie; Pingitore, Francesco; Mukhopadhyay, Aindrila; Phan, Richard; Hazen, Terry C.; Keasling, Jay D.

2007-01-01

106

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

PubMed

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

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

1990-04-01

107

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

PubMed

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

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

2005-09-16

108

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

109

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

110

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

111

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

Microsoft Academic Search

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

Maria Perla Colombini; Francesca Modugno; Ambrogio Giacomelli

1999-01-01

112

Metabolism studies of chlormethiazole by gas chromatography-mass spectrometry  

Microsoft Academic Search

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

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

1973-01-01

113

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...

114

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

Microsoft Academic Search

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

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

2003-01-01

115

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

Microsoft Academic Search

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

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

2003-01-01

116

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

Microsoft Academic Search

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

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

1998-01-01

117

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

Microsoft Academic Search

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

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

2006-01-01

118

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

Microsoft Academic Search

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

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

2003-01-01

119

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

Microsoft Academic Search

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

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

2005-01-01

120

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

Microsoft Academic Search

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

Ines Starke; Anja Holzberger; Birgit Kamm; Erich Kleinpeter

2000-01-01

121

Analysis of degradation products of organophosphorus chemical warfare agents and related compounds by liquid chromatography–mass spectrometry using electrospray and atmospheric pressure chemical ionisation  

Microsoft Academic Search

A qualitative screening procedure was developed for the detection and identification of phosphonic acid hydrolysis products of organophosphorus chemical warfare agents, using liquid chromatography–mass spectrometry with electrospray ionisation (LC–ESP-MS). A mixed C8\\/C18 reversed-phase column with gradient elution gave good chromatography for a series of phosphonic acids. Detection limits for aqueous solutions of standards were <50 ng\\/ml (<0.25 ng injected), providing

Robin M Black; Robert W Read

1998-01-01

122

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

Microsoft Academic Search

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

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

2003-01-01

123

Headspace in-tube extraction gas chromatography-mass spectrometry for the analysis of hydroxylic methyl-derivatized and volatile organic compounds in blood and urine.  

PubMed

A novel headspace in-tube extraction gas chromatography-mass spectrometry (ITEX-GC-MS) approach was developed for broad-scale analysis of low molecular weight organic compounds in blood and/or urine. One sample was analyzed following in-vial derivatization with dimethyl sulfate for ethylene glycol (EG), glycolic acid (GA), formic acid (FA), other hydroxylic compounds, and another sample for underivatized volatile organic compounds. Tenax adsorbent resin was used in the microtrap, and a porous layer, open tubular GC capillary column was used for separation. MS was operated in the full-scan mode, identification was based on the Automated Mass Spectral Deconvolution and Identification System, and quantification was based on extracted ions. The limits of quantification for EG, GA, and FA in blood were 10, 50, and 30 mg/L, respectively, and the expanded uncertainties of measurement were 20%, 16%, and 14%, respectively. The procedure allowed for the first time the inclusion of EG and GA as their methyl derivatives within a quantitative HS analysis. The ITEX method described here was more sensitive for analysis of volatile organic compounds than the corresponding static headspace analysis as demonstrated for 11 representative compounds. PMID:20406534

Rasanen, Ilpo; Viinamäki, Jenni; Vuori, Erkki; Ojanperä, Ilkka

2010-04-01

124

Multiresidue analysis of organochlorine and pyrethroid pesticides in ground beef meat by gas chromatography-mass spectrometry.  

PubMed

A multiresidue method was developed and optimized for the identification/quantification of organochlorine pesticides (OCPs) and pyrethroids (PYRs) in beef meat samples. Samples extraction was performed by an automated solvent extractor and the extracts were cleaned-up by a tandem-cartridge system consisting of an Extrelut NT3 combined with a Sep-Pack C18 cartridge and a florisil minicartridge. Analysis was finally carried out by gas chromatography coupled with quadrupole mass spectrometry (GC/MS). The performance of the method was investigated in terms of linearity, accuracy, precision, detection limit (LOD) and quantification limit (LOQ). Good linearity was obtained, with correlation coefficients (r(2)) higher than 0.98. Mean recoveries were found in the ranges 70-110 % and 84-99 % for the investigated OCPs and PYRs, respectively, with the exception of extremely volatile hexachlorobenzene (HCB). RSD% turned out to range from 2 to 15 %. LOQ values were in the range 0.005-0.1 mg/kg for either class of compounds. The method developed was successfully tested on 50 commercial beef meat samples from the market area of Rome (Italy), proving to be a useful tool in routine multiresidue analysis of OCPs and PYRs for monitoring purposes. None of the compounds of interest were observed above their respective LOQ. PMID:19365750

Stefanelli, Patrizia; Santilio, Angela; Cataldi, Lucilla; Dommarco, Roberto

2009-05-01

125

Analysis of organic acids in fruit juices by liquid chromatography-mass spectrometry: an enhanced tool for authenticity testing.  

PubMed

Organic acid analysis plays a fundamental role in the testing of authenticity of fruit juices. Analytical methods used routinely for organic acids suffer from poor reproducibility, often give false positives/negatives for tartaric acid, and do not offer the possibility of analyte confirmation. There are conflicting reports in the literature on the presence/absence of tartaric acid in pomegranate juice, a potential indicator of adulteration with grape juice. In this work, a method based on stable isotope dilution liquid chromatography-tandem mass spectrometry is described for citric, malic, quinic, and tartaric acid in fruit juices. Validation data including precision and recovery in six types of juice are presented. Tartaric and quinic acids were confirmed in pomegranate juice at concentrations of 1-5 and ?1 mg/L, respectively. These concentrations are much lower than those resulting from adulteration with grape juice and apple juice, respectively, at the 5% level. A separate method for isocitric acid in orange juice based on the single standard addition method is also described. PMID:21361392

Ehling, Stefan; Cole, Shannon

2011-02-28

126

Characterization of archaeological frankincense by gas chromatography–mass spectrometry  

Microsoft Academic Search

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

Carole Mathe; Gérald Culioli; Paul Archier; Cathy Vieillescazes

2004-01-01

127

Methods for supercritical fluid chromatography-mass spectrometry: New approaches  

SciTech Connect

Supercritical Fluid Chromatography-Mass Spectrometry (SFC-MS) provides a significantly enhanced chromatographic efficiency per unit time compared to HPLC, and more than 3000 and 12,000 effective theoretical plates can be obtained with 50..mu..m and 25..mu..m (i.d.) columns, respectively. The mass spectrometer, with the ability to acquire both chemical ionization and electron ionization spectra, provides the basis for obtaining both high sensitivity and selectivity or structural information for identification of unknown materials. (WRF)

Smith, R.D.; Kalinoski, H.T.; Udseth, H.R.; Chess, E.K.

1986-09-01

128

Cortisol production rates measured by liquid chromatography/mass spectrometry  

SciTech Connect

Cortisol production rates (FPRs) in physiologic and pathologic states in humans have been investigated over the past 30 years. However, there has been conflicting evidence concerning the validity of the currently accepted value of FPRs in humans (12 to 15 mg/m2/d) as determined by radiotracer methodology. The present study reviews previous methods proposed for the measurement of FPRs in humans and discusses the applications of the first method for the direct determination of 24-hour plasma FPRs during continuous administration of a stable isotope, using a thermospray high-pressure liquid chromatography-mass spectrometry technique. The technique is fast, sensitive, and, unlike gas chromatography-mass spectrometry methods, does not require derivatization, allowing on-line detection and quantification of plasma cortisol after a simple extraction procedure. The results of determination of plasma FPRs by stable tracer/mass spectrometry are directly in units of mass/time and, unlike radiotracer methods, are independent of any determination of volume of distribution or cortisol concentration. Our methodology offers distinct advantages over radiotracer techniques in simplicity and reliability since only single measurements of isotope ratios are required. The technique was validated in adrenalectomized patients. Circadian variations in daily FRPs were observed in normal volunteers, and, to date, results suggest a lower FRP in normal children and adults than previously believed. 88 references.

Esteban, N.V.; Yergey, A.L. (National Institute of Child Health and Human Development, Bethesda, MD (USA))

1990-04-01

129

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

PubMed

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

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

2012-01-04

130

Evaluation of solid-phase micro-extraction coupled to gas chromatography-mass spectrometry for the headspace analysis of volatile compounds in cocoa products.  

PubMed

The aroma profile of cocoa products was investigated by headspace solid-phase micro-extraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS). SPME fibers coated with 100 microm polydimethylsiloxane coating (PDMS), 65 microm polydimethylsiloxane/divinylbenzene coating (PDMS-DVB), 75 microm carboxen/polydimethylsiloxane coating (CAR-PDMS) and 50/30 microm divinylbenzene/carboxen on polydimethylsiloxane on a StableFlex fiber (DVB/CAR-PDMS) were evaluated. Several extraction times and temperature conditions were also tested to achieve optimum recovery. Suspensions of the samples in distilled water or in brine (25% NaCl in distilled water) were investigated to examine their effect on the composition of the headspace. The SPME fiber coated with 50/30 microm DVB/CAR-PDMS afforded the highest extraction efficiency, particularly when the samples were extracted at 60 degrees C for 15 min under dry conditions with toluene as an internal standard. Forty-five compounds were extracted and tentatively identified, most of which have previously been reported as odor-active compounds. The method developed allows sensitive and representative analysis of cocoa products with high reproducibility. Further research is ongoing to study chocolate making processes using this method for the quantitative analysis of volatile compounds contributing to the flavor/odor profile. PMID:18371766

Ducki, Sylvie; Miralles-Garcia, Javier; Zumbé, Albert; Tornero, Antonio; Storey, David M

2007-09-02

131

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

PubMed

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

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

2011-10-01

132

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

133

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

PubMed

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

Doneanu, Catalin E; Xenopoulos, Alex; Fadgen, Keith; Murphy, Jim; Skilton, St John; Prentice, Holly; Stapels, Martha; Chen, Weibin

134

In situ silylation for the multicomponent analysis of canola oil by-products by gas chromatography–mass spectrometry  

Microsoft Academic Search

In this study, a simple method for the determination of free fatty acids, phytosterols, tocopherols, mono and diglycerides present in canola oil deodorizer distillate (DD) and soapstock samples was developed. Analytes were derivatized “in situ” using a mixture of hexamethyldisilazane (HMDS), pyridine and trifluoroacetic acid; separated by gas chromatography (GC) with mass spectrometry (MS) for final detection. Two drying procedures

Armando A. Durant; Marie-Josée Dumont; Suresh S. Narine

2006-01-01

135

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

USGS Publications Warehouse

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

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

2001-01-01

136

Analysis of linear alkylbenzene sulfonate homologues in environmental water samples by mixed admicelle-based extraction and liquid chromatography/mass spectrometry.  

PubMed

Hemimicelles and admicelles of cetyltrimethylammonium bromide (CTAB) and cetylpyridinium chloride (CPC), adsorbed onto silica, were tested as sorbents for the solid phase extraction (SPE) of linear alkylbenzene sulfonate (LAS) homologues from environmental water samples. LASs were quantitatively retained on both surfactants due to high hydrophobic and ionic interactions, which led to the formation of analyte-extractant mixed aggregates. Parameters affecting the SPE of LASs were optimised. Recoveries of analytes from wastewater influent and effluent and river water samples ranged between 86 and 110%. Combination of SPE with liquid chromatography/mass spectrometry provided detection limits for the different LAS homologues of about 4 ng L(-1). The precision of the method, expressed as relative standard deviation, ranged from 5 to 9%. The method was applied to the analysis of LASs in wastewater and river samples using sample volumes between 10 and 25 mL. The LAS concentrations found ranged from 9 to 503 microg L(-1). No cleaning step was required to get accurate results. PMID:16802030

Lunar, Loreto; Rubio, Soledad; Pérez-Bendito, Dolores

2006-05-19

137

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

PubMed

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

Tölgyessy, Peter; Vrana, Branislav; Krascsenits, Zoltán

2011-10-01

138

Trace analysis of ethanol, MTBE, and related oxygenate compounds in water using solid-phase microextraction and gas chromatography/mass spectrometry.  

PubMed

Solid-phase microextraction (SPME) and gas chromatography/mass spectrometry have been combined for trace-level determination of very polar compounds in water, including the widely used gasoline oxygenates ethanol and methyl tert-butyl ether (MTBE). A relatively simple extraction method using a divinylbenzene/Carboxen/poly(dimethylsiloxane) SPME fiber was optimized for the routine analysis of ethanol and MTBE in groundwater and reagent water. A sodium chloride concentration of 25% (w/w) combined with an extraction time of 25 min provided the greatest sensitivity while maintaining analytical efficiency. Replicate analyses in fortified reagent and groundwater spiked with microgram per liter concentrations of ethanol and MTBE indicate quantitative and reproducible recovery of these and related oxygenate compounds. Method detection limits were 15 microg L(-1) for ethanol, 1.8 microg L(-1) for tert-butyl alcohol, 0.038 microg L(-1) for tert-amyl methyl ether, 0.025 microg L(-1) for ethyl-tert-butyl ether, and 0.008 microg L(-1) for MTBE. PMID:11028625

Cassada, D A; Zhang, Y; Snow, D D; Spalding, R F

2000-10-01

139

Analysis of cytochrome P450 metabolites of arachidonic and linoleic acids by liquid chromatography-mass spectrometry with ion trap MS.  

PubMed

We have used reversed phase-high performance liquid chromatography-mass spectrometry (RP-HPLC-MS) with an ion trap mass spectrometer to study the metabolism of arachidonic and linoleic acids by human recombinant cytochrome P450 (CYP) enzymes. We first recorded the MS2 spectra of the carboxylate anions of epoxides, diols, omega-side chain, and bisallylic hydroxy fatty acids of arachidonic, octadeuterated arachidonic, and linoleic acids. The metabolites formed by CYP2C9 and CYP2C19 were then studied. CYP2C9 converted arachidonic and linoleic acids to epoxides/diols and monohydroxy fatty acids. Some hydroxyeicosatetraenoic acids (HETEs) were studied in detail to investigate the oxygenation mechanism. Incubation of CYP2C9 under oxygen-18 gas showed that all HETEs had incorporated oxygen-18 to the same degree. Chiral HPLC showed that CYP2C9 formed 15R-HETE (72% of the R enantiomer), 13S-HETE (90%), and 11R-HETE (57%). RP-HPLC-MS analysis revealed that CYP2C19 oxygenated arachidonic acid to 19-HETE, 14,15-epoxyeicosatrienoic acid (EET), and 8,9-EET as main metabolites. The method was sufficiently sensitive to identify arachidonic acid metabolites formed by some other isozymes. RP-HPLC-MS with MS2 seems to be useful for rapid identification of fatty acid metabolites in complex mixtures formed by cytochrome P450. PMID:9866708

Bylund, J; Ericsson, J; Oliw, E H

1998-12-01

140

The mechanism of adenosine to inosine conversion by the double-stranded RNA unwinding/modifying activity: A high-performance liquid chromatography-mass spectrometry analysis  

SciTech Connect

The authors have used directly combined high-performance liquid chromatography-mass spectrometry (LC/MS) to examine the mechanism of the reaction catalyzed by the double-stranded RNA unwinding/modifying activity. A double-stranded RNA substrate in which all adenosines were uniformly labeled with {sup 13}C was synthesized. An LC/MS analysis of the nucleoside products from the modified, labeled substrate confirmed that adenosine is modified to inosine during the unwinding/modifying reaction. Most importantly, they found that no carbons are exchanged during the reaction. By including H{sub 2} {sup 18}O in the reaction, they showed that water serves efficiently as the oxygen donor in vitro. These results are consistent with a hydrolytic deamination mechanism and rule out a base replacement mechanism. Although the double-stranded RNA unwinding/modifying activity appears to utilize a catalytic mechanism similar to that of adenosine deaminase, coformycin, a transition-state analogue, will not inhibit the unwinding/modifying activity.

Polson, A.G.; Crain, P.F.; Pomerantz, S.C.; McCloskey, J.A.; Bass, B.L. (Univ. of Utah, Salt Lake City (United States))

1991-12-10

141

Novel biomarkers of 3-chloro-1,2-propanediol exposure by ultra performance liquid chromatography/mass spectrometry based metabonomic analysis of rat urine.  

PubMed

To select early, sensitive biomarkers of 3-chloro-1,2-propanediol (3-MCPD) exposure, a single dose of 30 mg/kg/day 3-MCPD was administered to male Wistar rats for 40 days. Significant elevations of serum creatinine and blood urea nitrogen concentrations were observed on day 40, and urine N-acetyl-beta-D-glucosaminidase and beta-galactosidase (beta-Gal) activities were observed on day 20. Slight renal tubule hydropic degeneration and spermatozoa decreases were observed on day 10. The endogenous metabolite profile of rat urine was investigated by ultra performance liquid chromatography/mass spectrometry with electrospray ionization (ESI). Principal component analysis and partial least-squares enabled clusters to be visualized, with a trend of clustering on day 10 in ESI- and the greatest differences on days 30 and 40. Galactosylglycerol, a marker contributing to the clusters, which had earlier variations than conventional biomarkers and the most significant elevations as compared to other novel biomarkers, was first considered to be an early, sensitive biomarker in evaluating the effect of 3-MCPD exposure. The identification of galactosylglycerol was carried out by beta-Gal catalysis, and the possible mechanism of urine galactosylglycerol variation was elucidated. PMID:20158273

Li, Ying; Liu, Shuang; Wang, Cheng; Li, Kang; Shan, Yu-Juan; Wang, Xi-Jun; Sun, Chang-Hao

2010-06-21

142

Use of gas liquid chromatography/mass spectrometry for triazine herbicide residues analysis in forage and milk.  

PubMed

Residual s-triazines were isolated from forage and milk samples by methanol/chloroform extraction followed by column purification. The evaporated extracts were dissolved in acetone and analysed by gas chromatography with NPD detection and mass spectrometry. The detection limits for both methods were found to be about 5 approximately 10 ng of each s-triazine. The selective ions of the 10 s-triazines investigated (simazine, atrazine, propazine, terbuthylazine, cyanazine, desmetryne, ametryne, prometryne, terbutryne and methoprotryne) were chosen on the basis of an electron impact mass spectrometry study of the s-triazine standards and the whole mass spectra are given. Special attention was paid to the fragmentation of cyanazine and the general cleavage pathways of the s-triazines under investigation. PMID:3660950

Víden, I; Rathouská, Z; Davídek, J; Hajslová, J

1987-08-01

143

Full-range analysis of ambient volatile organic compounds by a new trapping method and gas chromatography\\/mass spectrometry  

Microsoft Academic Search

This study investigated the feasibility of analyzing a full range of ambient volatile organic compounds (VOCs) from C3 to C12 using gas chromatograph mass spectrometry (GC\\/MS) coupled with thermal desorption. Two columns were used: a PLOT column separated compounds lighter than C6 and a DB-1 column separated C6–C12 compounds. An innovative heart-cut technique based on the Deans switch was configured

Yuan-Chang Su; Wen-Tzu Liu; Wei-Cheng Liao; Sen-Wei Chiang; Jia-Lin Wang

2011-01-01

144

Recent applications of liquid chromatography–mass spectrometry to residue analysis of antimicrobials in food of animal origin  

Microsoft Academic Search

Residual antimicrobials in food constitute a risk to human health. Although epidemiological data on the real magnitude of\\u000a their adverse effects are very scarce, they indicate that food could be an important vehicle for evolution and dissemination\\u000a of antimicrobial-resistant bacteria. Public health agencies in many countries rely on detection by mass spectrometry (MS)\\u000a for unambiguous identification of residues of antimicrobial

Sara Bogialli; Antonio Di Corcia

2009-01-01

145

Gas chromatography mass spectrometry-based metabolite profiling in plants.  

PubMed

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

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

2006-01-01

146

Chromatographic fingerprint analysis of secondary metabolites in citrus fruits peels using gas chromatography-mass spectrometry combined with advanced chemometric methods.  

PubMed

Multivariate curve resolution (MCR) and multivariate clustering methods along with other chemometric methods are proposed to improve the analysis of gas chromatography-mass spectrometry (GC-MS) fingerprints of secondary metabolites in citrus fruits peels. In this way, chromatographic problems such as baseline/background contribution, low S/N peaks, asymmetric peaks, retention time shifts, and co-elution (overlapped and embedded peaks) occurred during GC-MS analysis of chromatographic fingerprints are solved using the proposed strategy. In this study, first, informative GC-MS fingerprints of citrus secondary metabolites are generated and then, whole data sets are segmented to some chromatographic regions. Each chromatographic segment for eighteen samples is column-wise augmented with m/z values as common mode to preserve bilinear model assumption needed for MCR analysis. Extended multivariate curve resolution alternating least squares (MCR-ALS) is used to obtain pure elution and mass spectral profiles for the components present in each chromatographic segment as well as their relative concentrations. After finding the best MCR-ALS model, the relative concentrations for resolved components are examined using principal component analysis (PCA) and k-nearest neighbor (KNN) clustering methods to explore similarities and dissimilarities among different citrus samples according to their secondary metabolites. In general, four clear-cut clusters are determined and the chemical markers (chemotypes) responsible to this differentiation are characterized by subsequent discriminate analysis using counter-propagation artificial neural network (CPANN) method. It is concluded that the use of proposed strategy is a more reliable and faster way for the analysis of large data sets like chromatographic fingerprints of natural products compared to conventional methods. PMID:22766429

Parastar, Hadi; Jalali-Heravi, Mehdi; Sereshti, Hassan; Mani-Varnosfaderani, Ahmad

2012-06-15

147

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

148

An alternative derivatization method for the analysis of amino acids in cerebrospinal fluid by gas chromatography-mass spectrometry.  

PubMed

The determination of the concentrations of l-amino acids in cerebrospinal fluid (CSF) has been used to gain biochemical insight into central nervous system disorders. This paper describes a microwave-assisted derivatization (MAD) method using N,O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA) as a derivatizing agent for determining the concentrations of l-amino acids in human CSF by gas chromatography with mass spectrometry (GC/MS). The experimental design used to optimize the conditions showed that the optimal derivatization time was 3min with a microwave power of 210W. The method showed good performance for the validation parameters. The sensitivity was very good, with limits of detection (LODs) ranging from 0.01?molL(-1) to 4.24?molL(-1) and limits of quantification (LOQs) ranging from 0.02 to 7.07?molL(-1). The precision, measured using the relative standard deviation (RSD), ranged from 4.12 to 15.59% for intra-day analyses and from 6.36 to 18.71% for inter-day analyses. The coefficients of determination (R(2)) were above 0.990 for all amino acids. The optimized and validated method was applied to the determination of amino acid concentrations in human CSF. PMID:23770739

de Paiva, Maria José Nunes; Menezes, Helvécio Costa; Christo, Paulo Pereira; Resende, Rodrigo Ribeiro; Cardeal, Zenilda de Lourdes

2013-05-25

149

Metabonomics analysis of urine and plasma from rats given long-term and low-dose dimethoate by ultra-performance liquid chromatography-mass spectrometry.  

PubMed

This study assessed the effects of long-term, low-dose dimethoate administration to rats by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). Dimethoate (0.04, 0.12, and 0.36 mg/kg body weight/day) was administered daily to male Wistar rats through their drinking water for 24 weeks. Significant changes in serum clinical chemistry were observed in the middle- and high-dose groups. UPLC-MS revealed evident separate clustering among the different dose groups using global metabolic profiling by supervised partial least squares-discriminant analysis. Metabonomic analysis showed alterations in a number of metabolites (12 from urine and 13 from plasma), such as L-tyrosine, dimethylthiophosphate (DMTP), dimethyldithiophosphate (DMDTP), citric acid, uric acid, suberic acid, glycylproline, allantoin, isovalerylglutamic acid and kinds of lipids. The results suggest that long-term, low-dose exposure to dimethoate can cause disturbances in liver function, antioxidant and nervous systems, as well as the metabolisms of lipids, glucose, fatty acids, amino acids, and collagen in rats. DMTP and DMDTP, which had the most significant changes among all other studied biomarkers, were considered as early, sensitive biomarkers of exposure to dimethoate. The other aforementioned proposed toxicity biomarkers in metabonomic analysis may be useful in the risk assessment of the toxic effects of dimethoate. Metabonomics as a systems toxicology approach was able to provide comprehensive information on the dynamic process of dimethoate induced toxicity. In addition, the results indicate that metabonomic approach could detect systemic toxic effects at an earlier stage compared to clinical chemistry. The combination of metabonomics and clinical chemistry made the toxicity of dimethoate on rats more comprehensive. PMID:22884955

Feng, Zhijing; Sun, Xiaowei; Yang, Jindan; Hao, Dongfang; Du, Longfei; Wang, Hong; Xu, Wei; Zhao, Xiujuan; Sun, Changhao

2012-08-03

150

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

PubMed

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

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

2008-03-02

151

Microwave synthesis of gibberellin acid 3 magnetic molecularly imprinted polymer beads for the trace analysis of gibberellin acids in plant samples by liquid chromatography-mass spectrometry detection.  

PubMed

In this study, novel GA3 magnetic molecularly imprinted polymer (mag-MIP) beads were synthesized by a microwave irradiation method, and the beads were applied for the trace analysis of gibberellin acids (GAs) in plant samples including rice and cucumber coupled with high performance liquid chromatography-mass spectrometry (HPLC-MS). The microwave synthetic procedure was optimized in detail. In particular, the interaction between GA3 and functional monomers was further studied for the selection of the optimal functional monomers during synthesis. It can be seen that the interaction between GA3 and acrylamide (AM) finally selected was stronger than that between GA3 and other functional monomers. GA3 mag-MIP beads were characterized by a series of physical tests. GA3 mag-MIP beads had a porous and homogeneous surface morphology with stable chemical, thermal and magnetic properties. Moreover, GA3 mag-MIP beads demonstrated selective and specific absorption behavior for the target compounds during unsaturated extraction, which resulted in a higher extraction capacity (?708.4 pmol for GA3) and selectivity than GA3 mag-non-imprinted polymer beads. Finally, an analytical method of GA3 mag-AM-MIP bead extraction coupled with HPLC-MS detection was established and applied for the determination of trace GA1, GA3, GA4 and GA7 in rice and cucumber samples. It was satisfactory that GA4 could be actually found to be 121.5 ± 1.4 ?g kg(-1) in real rice samples by this novel analytical method. The recoveries of spiked rice and cucumber samples were found to be 76.0-109.1% and 79.9-93.6% with RSDs of 2.8-8.8% and 3.1-7.7% (n = 3), respectively. The proposed method is efficient and applicable for the trace analysis of GAs in complicated plant samples. PMID:22182945

Zhang, Zhuomin; Tan, Wei; Hu, Yuling; Li, Gongke; Zan, Song

2011-12-20

152

EVALUATION OF PARTICLE BEAM LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY FOR THE ANALYSIS OF POLAR SEMIVOLATILE ORGANIC COMPOUNDS IN AIR SAMPLES  

EPA Science Inventory

This report describes the initial evaluation of a particle beam liquid chromatograph/mass spectrometer for the analysis of polar semivolatile organic compounds in air samples. This study was concentrated on examining and optimizing instrumental operating parameters, evaluating th...

153

Total on-line analysis of a target protein from plasma by immunoextraction, digestion and liquid chromatography–mass spectrometry  

Microsoft Academic Search

A total on-line analysis of a target protein from a plasma sample was made using a selective immunoextraction step coupled on-line to an immobilized enzymatic reactor (IMER) for the protein digestion followed by LC–MS\\/MS analysis. For the development of this device, cytochrome c was chosen as model protein due to its well-known sequence. An immunosorbent (IS) based on the covalent

A. Cingöz; F. Hugon-Chapuis; V. Pichon

2010-01-01

154

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

155

Challenges in the development of bioanalytical liquid chromatography-mass spectrometry method with emphasis on fast analysis.  

PubMed

The development of bioanalytical methods has become more and more challenging over the past years due to very demanding requirements in terms of method reliability, sensitivity, speed of analysis and sample throughput. LC-MS/MS has established itself as a method of choice for routine analysis of biological materials. A development of such method consists of several steps including sample preparation and clean-up step, efficient chromatographic separation, sensitive and selective detection of analytes in complex matrices, a choice of convenient data processing and calibration approach and finally method validation. Each of these steps has its own constraints and challenges, which are discussed in detail in this review. Novel and modern approaches in sample preparation, chromatography and detection are especially emphasized. Attention is paid to proper calibration approach and matrix effects that can seriously affect method accuracy and precision. PMID:22999195

Nováková, Lucie

2012-09-01

156

Chiral nano-liquid chromatography–mass spectrometry applied to amino acids analysis for orange juice profiling  

Microsoft Academic Search

Determination of amino acid enantiomers is a very important topic in food analysis, since the presence of d-isomers may indicate, e.g., adulteration, microbiological contamination, uncontrolled fermentation processes, etc. In fact, the d- and l-enantiomers contents can be a useful marker for several elements such as quality control, contamination detection, processing monitoring, etc. Here we studied the potentiality of nano-liquid chromatography

Giovanni D’Orazio; Alejandro Cifuentes; Salvatore Fanali

2008-01-01

157

Liquid chromatography/mass spectrometry based fingerprinting analysis and mass profiling of Euterpe oleracea (açaí) dietary supplement raw materials.  

PubMed

Chemical fingerprinting and mass profiling methods to identify biologically active compounds in botanical dietary supplements is gaining much attention in recent years. Euterpe oleracea (açaí) has been reported to be rich in health-beneficial chemical constituents. We have developed LC/MS based fingerprinting and mass profiling methods to identify fatty acids, anthocyanins and non-anthocyanin polyphenols in three processed raw materials; non-organic açaí powder (ADSR-1), raw-organic açaí powder (ADSR-2) and freeze-dried açaí powder (ADSR-3) that are used in the preparation of botanical dietary supplements. For LC/MS analysis of fatty acids and non-anthocyanin polyphenols, the açaí samples were extracted sequentially with dichloromethane followed by methanol. To study fingerprinting analysis of anthocyanins, açaí samples were extracted with acidic methanol-water. The LC separation of fatty acids, non-anthocyanin polyphenols and anthocyanins in açaí raw materials was achieved using a C18 column with a gradient mobile phase consisting of solvents A (0.1% formic acid in water), and B (0.1% formic acid in methanol). MS experiments were carried out with negative and positive mode electrospray ionization. LC/MS analysis of dichloromethane extracts of (ADSR-1), (ADSR-2) and (ADSR-3) açaí powders have shown to contain fatty acids, ?-linolenic acid, linoleic acid, palmitic acid, and oleic acid. Whereas, the fingerprinting analysis of methanol extracts of ADSR-1, ADSR-2 and ADSR-3 led to the identification of phenolic acids, anthocyanin and non-anthocyanin polyphenols. The results from our study may be useful for the authentication and quality assessment of açaí dietary supplement raw materials. PMID:23107743

Mulabagal, Vanisree; Calderón, Angela I

2012-02-27

158

? 2Adrenergic agonist residues: simultaneous methyl- and butylboronic derivatization for confirmatory analysis by gas chromatography–mass spectrometry  

Microsoft Academic Search

A derivatization procedure for confirmatory residue analysis of ?2-agonists is described. Methyl (MBA) and butyl (BBA) boronic acids are simultaneously used for the derivatization of tulobuterol, mabuterol, mapenterol, salbutamol, clenproperol, clenbuterol, clenpenterol and bromobuterol by GC–MS determination. A temperature of 55°C during 60 min was selected as optimal temperature–time condition for simultaneous MBA and BBA ?2-agonists derivatization. It was also

Fernando Ramos; Cristina Santos; Antonieta Silva; Maria Irene Noronha da Silveira

1998-01-01

159

Extraction of explosives from soil followed by gas chromatography-mass spectrometry analysis with negative chemical ionization.  

PubMed

A new, simple and accurate method for extraction of explosives from soil was developed and validated. The method includes one hour gentle extraction of compounds from soil in acetonitrile:dichloromethane 50:50 at 30°C. Further analysis was made with GC-MS using cool on-column injection and negative chemical ionization. The method increased the recovery of the more volatile products, generated higher accuracy and was extensively time-saving compared to the conventional EPA (US Environmental Protection Agency) 8330 method. Applications are demonstrated on commercial reference materials. PMID:22226557

Holmgren, Erik; Ek, Stefan; Colmsjö, Anders

2011-12-13

160

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

Microsoft Academic Search

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

Yan Wang; Hian Kee Lee

1998-01-01

161

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

Microsoft Academic Search

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

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

1999-01-01

162

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

PubMed

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

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

2009-01-01

163

A validated method for the analysis of cannabinoids in post-mortem blood using liquid-liquid extraction and two-dimensional gas chromatography-mass spectrometry.  

PubMed

A validated method for the identification and quantification of ?(9)-tetrahydrocannabinol (THC), cannabidiol (CBD), cannabinol (CBN), 11-hydroxy-?(9)-tetrahydrocannabinol (11-OH-THC) and 11-nor-?(9)-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) in post-mortem blood specimens is described. Liquid-liquid extraction was used to extract the cannabinoids from 1 mL of post-mortem blood. The extracts were derivatized with N-methyl-N-(trimethylsilyl)trifluoroacetamide. The final derivatized extracts were analyzed using two-dimensional gas chromatography-mass spectrometry. The limit of detection was 0.25 ng/mL for all analytes and the limit of quantification of the assay was 0.25 ng/mL for THC, CBN, 11-OH-THC and 0.5 ng/mL for CBD and THC-COOH. The assay was linear across the concentration range 0.25-50 ng/mL (determined with a low and a high calibration range) with correlation coefficients ?0.992 for all analytes. Inter-day and intra-day accuracy was within ±15% of the target concentration for all analytes. The co-efficients of variation (%CV) for inter-day and intra-day precision were ?12% for all analytes. The extraction efficiency was >73% for all analytes. The method has successfully been applied to 54 post-mortem blood specimens to date. To the authors knowledge this is the first validated 2D GC-MS method for the analysis of THC, CBD, CBN, 11-OH-THC and THC-COOH following LLE and its application to post-mortem specimens. PMID:22717553

Andrews, Rebecca; Paterson, Sue

2012-06-18

164

Simultaneous analysis of pesticides from different chemical classes by using a derivatisation step and gas chromatography-mass spectrometry.  

PubMed

This work presents a new method to analyse simultaneously by GC-MS 31 pesticides from different chemical classes (2,4 D, 2,4 MCPA, alphacypermethrin, bifenthrin, bromoxynil, buprofezin, carbaryl, carbofuran, clopyralid, cyprodinil, deltamethrin dicamba, dichlobenil, dichlorprop, diflufenican, diuron, fenoxaprop, flazasulfuron, fluroxypyr, ioxynil, isoxaben, mecoprop-P, myclobutanil, oryzalin, oxadiazon, picloram, tau-fluvalinate tebuconazole, triclopyr, trifluralin and trinexapac-p-ethyl). This GC-MS method will be applied to the analysis of passive samplers (Tenax(®) tubes and SPME fiber) used for the evaluation of the indoor and outdoor atmospheric contamination by non-agricultural pesticides. The method involves a derivatisation step for thermo-labile or polar pesticides. Different agents were tested and MtBSTFA (N-(t-butyldimethylsilyl)-N-methyltrifluoroacetamide), a sylilation agent producing very specific fragments [M-57], was retained. However, diuron could not be derivatised and the isocyanate product was used for identification and quantification. Pesticides which did not need a derivatisation step were not affected by the presence of the derivatisation agent and they could easily be analysed in mixture with derivatised pesticides. The method can be coupled to a thermal-desorption unit or to SPME extraction for a multiresidue analysis of various pesticides in atmospheric samples. PMID:21962330

Raeppel, Caroline; Nief, Marie; Fabritius, Marie; Racault, Lucie; Appenzeller, Brice M; Millet, Maurice

2011-09-10

165

Isolation of polyketides from Prymnesium parvum (Haptophyta) and their detection by liquid chromatography/mass spectrometry metabolic fingerprint analysis.  

PubMed

Prymnesium parvum is a microalga that forms blooms coupled with the presence of potent exotoxins; however, no chemical standards are currently available for the toxins. Streamlined methods are presented for the separation and enrichment of polyketide toxins, prymnesin-1 (prym1) and prymnesin-2 (prym2). Prymnesins were separated by reversed-phase chromatography and detected by positive-mode electrospray ionization MS to generate a unique metabolic fingerprint. More than 10 ions were detected and mass assignments were in agreement with predicted isotopic distributions for the intact compounds and related fragments; ions occurred as multiply protonated species and with common salt adducts. The most prevalent ion was observed at 919.88 m/z, which represents the aglycone [prymagly+2H](2+) backbone structure common to both molecules. Expanded mass spectra for this and related ions were in excellent agreement (<0.5ppm) with empirically derived spectra based on elemental composition and naturally occurring isotopes. These investigations have confirmed the isolation of polyketide prymnesins from whole cells, which heretofore has not been reproduced since their original characterization. Moreover, this study represents the first time these compounds have been verified in aqueous materials. These tools should allow the direct identification and analysis of polyketide prymnesins, which will greatly improve our understanding of these toxins in P. parvum. PMID:23916560

Manning, Schonna R; La Claire Ii, John W

2013-08-02

166

Higher mass loadability in comprehensive two-dimensional gas chromatography-mass spectrometry for improved analytical performance in metabolomics analysis.  

PubMed

A major challenge in metabolomics analysis is the accurate quantification of metabolites in the presence of (extremely) high abundant metabolites. Quantification of metabolites at low concentrations can be complicated by co-elution and/or peak distortion when these metabolites elute close to high abundant metabolites. To increase the separation efficiency a comprehensive two-dimensional gas chromatographic-mass spectrometric method (GC x GC-MS) was set up, in which a polar first dimension column and an apolar second dimension column were used to maximize the peak capacity. The feasibility of using wider bore, thicker film columns in the second dimension to improve the mass loadability and inertness of the analytical system was investigated. Several column combinations with varying second dimension column dimensions were compared with a setup with a narrow bore column (0.1mm I.D.) in the second dimension. With a wider bore column (0.32 mm I.D.) in the second dimension the mass loadability was improved 10-fold, and the more inert column surface of the thicker film second dimension column resulted in a more accurate (automated) quantification and improved linearity in the presence of high concentrations of matrix compounds or metabolites. These benefits amply compensated the observed decrease in peak capacity of 40% compared to the narrow bore (0.1mm I.D.) thin film second dimension column. Compared to GC-MS and conventional GC x GC-MS, better performance for quantification of metabolites for typical metabolomics samples was achieved. PMID:18155223

Koek, Maud M; Muilwijk, Bastiaan; van Stee, Leo L P; Hankemeier, Thomas

2007-12-07

167

Pitfalls encountered during quantitative determination of 3-alkyl-2-methoxypyrazines in grape must and wine using gas chromatography-mass spectrometry with stable isotope dilution analysis. Comprehensive two-dimensional gas chromatography-mass spectrometry and on-line liquid chromatography-multidimensional gas chromatography-mass spectrometry as potential loopholes.  

PubMed

The analysis of 3-alkyl-2-methoxypyrazines in Vitis vinifera grape must or wine at the low nanogram per liter level failed in several situations when applying a one-dimensional gas chromatographic analysis with mass spectrometric detection (GC-MS). Sample preparation methods such as headspace solid phase microextraction or solid phase extraction were convenient procedures, however lacking extraction selectivity for complex matrices. Analysis by comprehensive two-dimensional gas chromatography with mass spectrometric detection clearly demonstrated the potential for co-elution in such matrices and the risk for erroneous results when applying one-dimensional GC-MS. In one example, matrix problems would have been a challenge even for a comprehensive two-dimensional chromatographic approach with MS detection (GC×GC-MS). A solution to matrix problems was found by protonating the 3-alkyl-2-methoxypyrazines in acidic pH and sample clean-up using solid phase extraction with a mixed-mode polymeric cation-exchange sorbent. Quantification was performed by a stable isotope dilution assay, following analysis by on-line coupled high performance liquid chromatography with multidimensional gas chromatography and detection with mass spectrometry (on-line LC-MDGC-MS). This new approach allowed trace-level analysis of 3-alkyl-2-methoxypyrazines in grape musts and wines and is described for V. vinifera Sauvignon blanc, following 3-alkyl-2-methoxypyrazines concentrations during ripening and in the processed wines. PMID:20637469

Schmarr, Hans-Georg; Ganss, Sebastian; Koschinski, Stefan; Fischer, Ulrich; Riehle, Carmen; Kinnart, Julian; Potouridis, Theodoros; Kutyrev, Maria

2010-06-25

168

Global urinary metabolic profiling procedures using gas chromatography–mass spectrometry  

Microsoft Academic Search

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

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

2011-01-01

169

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

Microsoft Academic Search

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

Vladimir A Liki?

2009-01-01

170

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

Microsoft Academic Search

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

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

2002-01-01

171

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

Microsoft Academic Search

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

C. A Lytle; W Bertsch; M McKinley

1998-01-01

172

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

173

Analysis of 18 perfluorinated compounds in river waters: comparison of high performance liquid chromatography-tandem mass spectrometry, ultra-high-performance liquid chromatography-tandem mass spectrometry and capillary liquid chromatography-mass spectrometry.  

PubMed

In this work, the performance of ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and capillary liquid chromatography-mass spectrometry (CLC-MS) has been studied for the analysis of eighteen perfluorinated compounds in water samples. UHPLC-MS/MS and CLC-MS analysis were carried out using a Zorbax C-18 column (50 mm × 2.1 mm, 1.8 ?m) and a Zorbax SB-C18 column (150 mm × 0.5 mm, 3.5 ?m), respectively, in gradient elution mode with a mobile phase of ammonium formate and methanol. Both techniques were compared with conventional LC-MS/MS in terms of speed, sensitivity, selectivity and resolution. Water samples were extracted by solid phase extraction (SPE). Mean absolute recoveries at two concentration levels, 6 and 60 ng L?¹, calculated from the eighteen compounds were: 77 ± 12(s) and 82 ± 12(s), respectively. Relative standard deviation (RSD) was lower than 16% for each perfluorinated compound. The results obtained showed that UHPLC-MS/MS and CLC-MS allow the determination of perfluorinated compounds in water samples with satisfactory sensitivity and resolution and reduced analysis time. Therefore, both techniques were employed for the analysis of water samples to determine the target analytes at low concentration levels and with lower analysis times than using HPLC-MS/MS. Similar statistical values were obtained from both techniques at 95% confidence level. Several compounds have been detected, but perfluorooctanoic acid (PFOA) (171 ng L?¹ and 148 ng L?¹ by UHPLC-MS/MS and CLC-MS, respectively) showed the highest concentration. PMID:22633866

Onghena, Matthias; Moliner-Martinez, Y; Picó, Yolanda; Campíns-Falcó, P; Barceló, Damià

2012-05-08

174

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory : determination of polycyclic aromatic hydrocarbon compounds in sediment by gas chromatography/mass spectrometry  

USGS Publications Warehouse

A method for the determination of 28 polycyclic aromatic hydrocarbons (PAHs) and 25 alkylated PAH homolog groups in sediment samples is described. The compounds are extracted from sediment by solvent extraction, followed by partial isolation using high-performance gel permeation chromatography. The compounds are identified and uantitated using capillary-column gas chromatography/mass spectrometry. The report presents performance data for full-scan ion monitoring. Method detection limits in laboratory reagent matrix samples range from 1.3 to 5.1 micrograms per kilogram for the 28 PAHs. The 25 groups of alkylated PAHs are homologs of five groups of isomeric parent PAHs. Because of the lack of authentic standards, these homologs are reported semiquantitatively using a response factor from a parent PAH or a specific alkylated PAH. Precision data for the alkylated PAH homologs are presented using two different standard reference manuals produced by the National Institute of Standards and Technology: SRM 1941b and SRM 1944. The percent relative standard deviations for identified alkylated PAH homolog groups ranged from 1.55 to 6.98 for SRM 1941b and from 6.11 to 12.0 for SRM 1944. Homolog group concentrations reported under this method include the concentrations of individually identified compounds that are members of the group. Organochlorine (OC) pesticides--including toxaphene, polychlorinated biphenyls (PCBs), and organophosphate (OP) pesticides--can be isolated simultaneously using this method. In brief, sediment samples are centrifuged to remove excess water and extracted overnight with dichloromethan (95 percent) and methanol (5 percent). The extract is concentrated and then filtered through a 0.2-micrometer polytetrafluoroethylene syringe filter. The PAH fraction is isolated by quantitatively injecting an aliquot of sample onto two polystyrene-divinylbenzene gel-permeation chromatographic columns connected in series. The compounds are eluted with dichloromethane, a PAH fraction is collected, and a portion of the coextracted interferences, including elemental sulfur, is separated and discarded. The extract is solvent exchanged, the volume is reduced, and internal standard is added. Sample analysis is completed using a gas chromatograph/mass spectrometer and full-scan acquisition.

Olson, Mary C.; Iverson, Jana L.; Furlong, Edward T.; Schroeder, Michael P.

2004-01-01

175

Dielectric barrier discharge ionization for liquid chromatography/mass spectrometry.  

PubMed

An atmospheric pressure microplasma ionization source based on a dielectric barrier discharge with a helium plasma cone outside the electrode region has been developed for liquid chromatography/mass spectrometry (LC/MS). For this purpose, the plasma was realized in a commercial atmospheric pressure ionization source. Dielectric barrier discharge ionization (DBDI) was compared to conventional electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photoionization (APPI) in the positive ionization mode. Therefore, a heterogeneous compound library was investigated that covered polar compounds such as amino acids, water-soluble vitamins, and nonpolar compounds like polycyclic aromatic hydrocarbons and functionalized hydrocarbons. It turned out that DBDI can be regarded as a soft ionization technique characterized by only minor fragmentation similar to APCI. Mainly protonated molecules were detected. Additionally, molecular ions were observed for polycyclic aromatic hydrocarbons and derivatives thereof. During DBDI, adduct formation with acetonitrile occurred. For aromatic compounds, addition of one to four oxygen atoms and to a smaller extend one nitrogen and oxygen was observed which delivered insight into the complexity of the ionization processes. In general, compounds covering a wider range of polarities can be ionized by DBDI than by ESI. Furthermore, limits of detection compared to APCI are in most cases equal or even better. PMID:19911793

Hayen, Heiko; Michels, Antje; Franzke, Joachim

2009-12-15

176

Optimization of antibiotic analysis in water by solid-phase extraction and high performance liquid chromatography-mass spectrometry/mass spectrometry.  

PubMed

This paper describes the development of an optimized method based on solid-phase extraction (SPE) followed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-MS/MS) for the simultaneous analysis of ten antibiotic compounds including tetracyclines, sulfonamides, macrolides and quinolones. LC-MS/MS sensitivity has been optimized by alterations to both LC and MS operations. Of the two high resolution columns tested, Waters Symmetry C(18) endcapped and Agilent Zorbax Bonus-RP, the latter was found to show better performance in producing sharp peaks and clear separation for most of the target compounds. Optimization of the MS fragmentation collision and cone energy enhanced the peak areas of the target analytes. The recovery of the target compounds from water samples was most efficient on Waters Oasis HLB SPE cartridge, while methanol was shown to be the most suitable solvent for desorbing the compounds from SPE. In addition, acidification of samples prior to SPE was shown to enhance the recovery of the compounds. To ensure a satisfactory recovery, the flow rate through SPE should be maintained at ?10 mL min(-1). The method was successfully applied to the analysis of antibiotics from environmental water samples, with concentrations being

Zhou, John L; Maskaoui, Khalid; Lufadeju, Adeleye

2012-04-25

177

Analysis of topiramate and its metabolites in plasma and urine of healthy subjects and patients with epilepsy by use of a novel liquid chromatography-mass spectrometry assay.  

PubMed

A novel liquid chromatography-mass spectrometry (LC-MS) method was developed and validated for quantification of topiramate (TPM) and its metabolites 10-hydroxy topiramate (10-OH-TPM), 9-hydroxy topiramate (9-OH-TPM), and 4,5-O-desisopropylidene topiramate (4,5-diol-TPM) in plasma and urine. The method uses 0.5 mL of plasma or 1 mL of urine that is extracted with diethyl ether and analyzed by LC-MS. Positive ion mode detection enables tandem mass spectrometric (MS/MS) identification of the aforementioned four compounds. Calibration curves of TPM, 4,5-diol-TPM, 9-OH-TPM, and 10-OH-TPM in plasma and urine were prepared and validated over the concentration range of 0.625 to 40 microg/mL using TPM-d(12) as an internal standard. Calibration curves were linear over this concentration range for TPM and its metabolites. Accuracy and precision ranged in urine from 83% to 114% and 4% to 13% (%CV), respectively, and in plasma from 82% to 108% and 6% to 13%, respectively. The applicability of the assay was evaluated by analyzing plasma samples from a healthy subject who received a single oral dose of TPM (200 mg) and urine samples from 11 patients with epilepsy treated with TPM (daily dose between 100 to 600 mg) alone or with other antiepileptic drugs. Only TPM was detected and quantified in the plasma samples, and its concentration ranged between 0.7 and 4.3 microg/mL. The concentrations of TPM and 10-OH TPM were quantifiable in all urine samples and ranged from 20 to 300 microg/mL for TPM and from 1 to 50 microg/mL for 10-OH-TPM. The metabolites 4,5-diol-TPM and 9-OH-TPM were also detected in all urine samples, but their concentrations were quantifiable only in 4 patients. An unidentified peak in the chromatograms obtained from patients' urine was attributed to 2,3-O-desisopropylidene topiramate (2,3-diol-TPM). Due to a lack of reference material of 2,3-diol TPM and the similar MS/MS spectrum with 4,5-diol-TPM, the calibration curves of 4,5-diol-TPM were used for the quantification of its isomer 2,3-diol-TPM. Based on these determinations, the apparent 2,3-diol-TPM-to-TPM concentration ratio in patients' urine ranged from 0.05 to 0.51 and the 10-OH-TPM-to-TPM ratio ranged from 0.02 to 0.17. In conclusion, a novel LC-MS method for the assay of TPM and four of its metabolites in plasma and urine was developed. Its utilization for analysis of urine samples from patients with epilepsy showed that the method was suitable for analysis of TPM and its metabolites in clinical samples. Two quantitatively significant TPM metabolites (10-OH-TPM and 2,3-diol-TPM) and two quantitatively minor metabolites (9-OH-TPM and 4,5-diol-TPM) were detected and quantified in urine samples from patients with epilepsy. PMID:12766560

Britzi, Malka; Soback, Stefan; Isoherranen, Nina; Levy, Rene' H; Perucca, Emilio; Doose, Dennis R; Maryanoff, Bruce E; Bialer, Meir

2003-06-01

178

CHARACTERIZATION OF ORGANICS IN TANNERY EFFLUENTS BY LIQUID CHROMATOGRAPHY MASS SPECTROMETRY  

EPA Science Inventory

Combined high performance liquid chromatography mass spectrometry using a moving belt interface has been used to study extracts from five tannery and leather finishing industry discharges. Liquid chromatographic separation was performed with a Zorbax CN column using a normal phas...

179

[Pplications of multi-micro-volume pressure-assisted derivatization reaction device for analysis of polar heterocyclic aromatic amines by gas chromatography-mass spectrometry].  

PubMed

A multi-micro-volume pressure-assisted derivatization reaction device has been designed and made for the silylation derivatization of polar heterocyclic aromatic amines by N-(tert-butyldimethylsilyl )-N-methyl-trifluoroacetamide (MTBSTFA) with 1% catalyst tert-butyldimethylchlorosilane (TBDMCS) at a high temperature. The tert-butyldimethylsilyl derivatives then could be automatically analyzed by gas chromatography-mass spectrometry. Using the pressure-assisted device, the silylation reaction may occur at a temperature higher than the boiling points of the reagents, and several micro-volume samples can be simultaneously pretreated in the same device to shorten the sample-preparation time and to improve the repeatability. The derivatization conditions including the headspace volume of the vial, the evaporative surface area of the reagent, derivatization temperature and time have been discussed for the use of the pressure-assisted device. The experimental results proved that the device is an effective way for the simultaneous derivatization of several micro-volume samples at a high temperature. Compared with a common device, the derivative amounts were obviously increased when using the pressure-assisted device at 90 degrees C. Quantitative derivatization can be achieved even at 150 degrees C while there was no common device could be applied at such a high temperature due to the heavy losses of reagents by evaporation. However, no obviously higher reaction speed has been observed in such a circumstance with a higher temperature and a higher pressure using the pressure-assisted device. PMID:23667982

Wang, Yiru; Chen, Fangxiang; Shi, Yamei; Tan, Connieal; Chen, Xi

2013-01-01

180

Analysis of semi-volatile organic compounds in indoor suspended particulate matter by thermal desorption coupled with gas chromatography/mass spectrometry.  

PubMed

People are exposed to multiple pollutants, especially indoors. In the perspective of a cumulative risk assessment, a multi-residue analytical method was developed to assess the contamination of indoor suspended particulate matter by 55 semi-volatile organic compounds (SVOCs) including musk fragrances, organochlorines (OCs), organophosphates (OPs), polycyclic aromatic hydrocarbons (PAHs), polybromodiphenylethers (PBDEs), polychlorobiphenyls (PCBs), phthalates and pyrethroids. It is based on thermal desorption (TD) coupled with gas chromatography/mass spectrometry (GC/MS). Once the thermal desorption conditions were optimized, the method was validated in terms of quantification limits and accuracy using a standard reference material (SRM 2585). Instrumental quantification limits were 10 pg (some OCs, some pyrethroids, musk fragrances, OPs, PAHs, PBDEs and PCBs), 100 pg (phthalates and other OCs) and 1000 pg (other pyrethroids) corresponding respectively to method quantification limits of 1, 10, and 100 pg/m³ for a sampled air volume of 20 m³. Calibration quadratic curves for ranges of 10-1000, 100-10,000, and 1000-100,000 pg, depending on the substance, exhibit determination coefficients above 0.999. Recoveries were between 61 and 96% for chlorinated pesticides, PAHs, PBDEs and PCBs present in the SRM 2585. A test of the method on indoor particulate matter samples (PM??) collected on quartz fiber filters in French dwellings demonstrated its ability to quantify SVOCs from a small amount of PM. PMID:22840824

Mercier, Fabien; Glorennec, Philippe; Blanchard, Olivier; Le Bot, Barbara

2012-07-16

181

Analysis of gamma-irradiated melon, pumpkin, and sunflower seeds by electron paramagnetic resonance spectroscopy and gas chromatography-mass spectrometry.  

PubMed

Seeds of melon (Citrullus lanatus var. sp.), pumpkin (Cucurbita moschata), and sunflower (Heliantus annus) were gamma-irradiated at 1, 3, 5, and 10 kGy and analyzed by electron paramagnetic resonance (EPR) and gas chromatography-mass spectrometry (GC-MS) according to EN1787:2000 and EN1785:2003, respectively. Distinguishable triplet signals due to the presence of induced cellulose radicals were found at 2.0010-2.0047 g in the EPR spectra. The gamma-irradiated radiolytic markers of 2-dodecylcyclobutanone (2-DCB) and 2-tetradecylcyclobutanone (2-TCB) were identified in all irradiated seed samples. Both the free radicals and the alkylcyclobutanones were found to increase with irradiation dose. In general, linear relationships between the amount of radicals and irradiation dosage could be established. Studies at an ambient temperature (20-25 degrees C) in a humidity-controlled environment showed a complete disappearance of the cellulosic peaks for irradiated samples upon 60 days of storage. Such instability behavior was considered to render the usefulness of using EPR alone in the determination of irradiated seed samples. On the other hand, 2-DCB and 2-TCB were also found to decompose rapidly (>85% loss after 120 days of storage), but the radiolytic markers remained quantifiable after 120 days of postirradiation storage. These results suggest that GC-MS is a versatile and complimentary technique for the confirmation of irradiation treatment to seeds. PMID:16968077

Sin, Della W M; Wong, Yiu Chung; Yao, Wai Yin

2006-09-20

182

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

183

Meeting challenges in forensic toxicology in Japan by liquid chromatography\\/mass spectrometry  

Microsoft Academic Search

Since liquid chromatography\\/mass spectrometry (LC\\/MS) was introduced in the field of forensic toxicology in Japan, many challenges were considered using this technique in an attempt to overcome the problems which remained unsolved using other techniques such as gas chromatography (GC), liquid chromatography (LC) and gas chromatography\\/mass spectrometry (GC\\/MS).We here review the analytical challenges carried out in Japan using LC\\/MS from

K Kudo; H Tsuchihashi; N Ikeda

2003-01-01

184

Rapid white truffle headspace analysis by proton transfer reaction mass spectrometry and comparison with solid-phase microextraction coupled with gas chromatography\\/mass spectrometry  

Microsoft Academic Search

The gastronomic relevance and high price of white truffle are related mainly to its unique aroma. Here we evaluate, for the first time, the possibility of characterizing in a rapid and non-destructive way the aroma of white truffles based on proton transfer reaction mass spectrometry {(PTR-MS).} We indicate that anonymous {PTR-MS} fingerprinting allows sample classification and we also compare qualitatively

Eugenio Aprea; Franco Biasioli; Silvia Carlin; Giuseppe Versini; TD Mark; Flavia Gasperi

2007-01-01

185

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

186

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

Microsoft Academic Search

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

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

1986-01-01

187

Doping control analysis of TB-500, a synthetic version of an active region of thymosin ??, in equine urine and plasma by liquid chromatography-mass spectrometry.  

PubMed

A veterinary preparation known as TB-500 and containing a synthetic version of the naturally occurring peptide LKKTETQ has emerged. The peptide segment (17)LKKTETQ(23) is the active site within the protein thymosin ?(4) responsible for actin binding, cell migration and wound healing. The key ingredient of TB-500 is the peptide LKKTETQ with artificial acetylation of the N-terminus. TB-500 is claimed to promote endothelial cell differentiation, angiogenesis in dermal tissues, keratinocyte migration, collagen deposition and decrease inflammation. In order to control the misuse of TB-500 in equine sports, a method to definitely identify its prior use in horses is required. This study describes a method for the simultaneous detection of N-acetylated LKKTETQ and its metabolites in equine urine and plasma samples. The possible metabolites of N-acetylated LKKTETQ were first identified from in vitro studies. The parent peptide and its metabolites were isolated from equine urine or plasma by solid-phase extraction using ion-exchange cartridges, and analysed by liquid chromatography-mass spectrometry (LC/MS). These analytes were identified according to their LC retention times and relative abundances of the major product ions. The peptide N-acetylated LKKTETQ could be detected and confirmed at 0.02 ng/mL in equine plasma and 0.01 ng/mL in equine urine. This method was successful in confirming the presence of N-acetylated LKKTETQ and its metabolites in equine urine and plasma collected from horses administered with a single dose of TB-500 (containing 10mg of N-acetylated LKKTETQ). To our knowledge, this is the first identification of TB-500 and its metabolites in post-administration samples from horses. PMID:23084823

Ho, Emmie N M; Kwok, W H; Lau, M Y; Wong, April S Y; Wan, Terence S M; Lam, Kenneth K H; Schiff, Peter J; Stewart, Brian D

2012-09-23

188

Preparation of polypyrrole-coated magnetic particles for micro solid-phase extraction of phthalates in water by gas chromatography-mass spectrometry analysis.  

PubMed

In this work, polypyrrole (PPy)-coated Fe(3)O(4) magnetic microsphere were successfully synthesized, and applied as a magnetic sorbent to extract and concentrate phthalates from water samples. The PPy-coated Fe(3)O(4) magnetic microspheres had the advantages of large surface area, convenient and fast separation ability. The PPy coating of magnetic microspheres contributed to preconcentration of phthalates from water sample, due to the ?-? bonding between PPy coating and the analytes. Also, the coating could prevent aggregation of the microspheres, and improve their dispersibility. In this study, seven kinds of phthalates were selected as model analytes, including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-iso-butyl phthalate (DIBP), di-n-butyl phthalate (DBP), benzylbutyl phthalate (BBP), di-(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DNOP), and gas chromatography-mass spectrometry (GC-MS) was introduced to detect the phthalates after sample pretreatment. Important parameters of the extraction procedure were investigated, and optimized including eluting solvent, the amount of Fe(3)O(4)@PPy particles, and extraction time. After optimization, the procedure took only 15 min to extract and concentrate analytes with high efficiency. Validation experiments showed that the optimized method had good linearity (0.985-0.998), precision (3.4-11.7%), high recovery (91.1-113.4%), and the limits of detection were from 0.006 to 0.068 ?g/L. The results indicated that the novel method had advantages of convenience, good sensitivity, high efficiency, and it could also be applied successfully to analyze phthalates in real water sample. PMID:21315359

Meng, Jiaoran; Bu, Jing; Deng, Chunhui; Zhang, Xiangmin

2011-01-27

189

Analysis of plasticizers and synthetic musks in cosmetic and personal care products by matrix solid-phase dispersion gas chromatography-mass spectrometry.  

PubMed

Matrix solid-phase dispersion (MSPD) and gas chromatography-mass spectrometry were used for the rapid determination of 18 plasticizers (phthalates and adipates), 7 polycyclic musks and 5 nitromusks, which makes a total of 30 targets, in both rinse-off and leave-on cosmetic formulations. The MSPD method was miniaturized and customized to avoid or minimize risks of phthalate contamination and to reduce residues and costs. The amount of sample and extraction solvent employed were 0.1g and 1mL, respectively. The procedure was optimized by means of an experimental design and under the optima conditions it showed satisfactory linearity, repeatability and intermediate precision. LOQs were, in general, in the low ngg(-1), and recoveries were quantitative for all the 18 plasticizers and the 12 fragrances. Twenty-six cosmetic products such as creams, emulsions, lotions, gels for the skin, bath and shower preparations, deodorants, hair-setting, hair-cleansing and hair-conditioning products, shaving products, and sunbathing products, were analyzed. Twenty-five out of thirty targets were detected in the samples. The most frequently found compounds were galaxolide and tonalide reaching concentrations above 0.1% (1000?gg(-1)), and diethyl phthalate (between 0.7 and 357?gg(-1)). The presence of banned substances (Regulation (EC) No. 1223/2009) such as dibutyl phthalate, diisobutyl phthalate, dimethoxyethyl phthalate, benzylbutyl phthalate, diethylhexyl phthalate, diisopentyl phthalate and dipentyl phthalate, musk ambrette and musk tibetene was confirmed in sixteen of the twenty-six personal care products (62%). PMID:23622555

Llompart, Maria; Celeiro, Maria; Pablo Lamas, J; Sanchez-Prado, Lucia; Lores, Marta; Garcia-Jares, Carmen

2013-03-30

190

Multiresidue analysis of acidic and polar organic contaminants in water samples by stir-bar sorptive extraction-liquid desorption-gas chromatography-mass spectrometry.  

PubMed

The feasibility of stir-bar sorptive extraction (SBSE) followed by liquid desorption in combination with large volume injection (LVI)-in port silylation and gas chromatography-mass spectrometry (GC-MS) for the simultaneous determination of a broad range of 46 acidic and polar organic pollutants in water samples has been evaluated. The target analytes included phenols (nitrophenols, chlorophenols, bromophenols and alkylphenols), acidic herbicides (phenoxy acids and dicamba) and several pharmaceuticals. Experimental variables affecting derivatisation yield and peak shape as a function of different experimental PTV parameters [initial injection time, pressure and temperature and the ratio solvent volume/N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide (MTBSTFA) volume] were first optimised by an experimental design approach. Subsequently, SBSE conditions, such as pH, ionic strength, agitation speed and extraction time were investigated. After optimisation, the method failed only for the extraction of most polar phenols and some pharmaceuticals, being suitable for the determination of 37 (out of 46) pollutants, with detection limits for these analytes ranging between 1 and 800 ng/L and being lower than 25 ng/L in most cases. Finally, the developed method was validated and applied to the determination of target analytes in various aqueous environmental matrices, including ground, river and wastewater. Acceptable accuracy (70-130%) and precision values (<20%) were obtained for most analytes independently of the matrix, with the exception of some alkylphenols, where an isotopically labelled internal standard would be required in order to correct for matrix effects. Among the drawbacks of the method, carryover was identified as the main problem even though the Twisters were cleaned repeatedly. PMID:17727869

Quintana, José Benito; Rodil, Rosario; Muniategui-Lorenzo, Soledad; López-Mahía, Purificación; Prada-Rodríguez, Darío

2007-08-11

191

Classification of high-speed gas chromatography–mass spectrometry data by principal component analysis coupled with piecewise alignment and feature selection  

Microsoft Academic Search

A useful methodology is introduced for the analysis of data obtained via gas chromatography with mass spectrometry (GC–MS) utilizing a complete mass spectrum at each retention time interval in which a mass spectrum was collected. Principal component analysis (PCA) with preprocessing by both piecewise retention time alignment and analysis of variance (ANOVA) feature selection is applied to all mass channels

Nathanial E. Watson; Matthew M. VanWingerden; Karisa M. Pierce; Bob W. Wright; Robert E. Synovec

2006-01-01

192

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

193

Ultra-performance liquid chromatography-mass spectrometry of proteins.  

PubMed

The commercialization of ultra-performance liquid chromatography (UPLC) has allowed more researchers to take advantage of the benefits of this work. Many researchers are exploring this technique to reduce analytical throughput and to increase resolution. The majority of this work has focused on small molecule analysis; however, this technique can provide the same advantages for the analysis of proteins. Traditionally, protein chromatography has suffered from a number of issues such as carryover, peak splitting, peak broadening, and poor peak shape. Because UPLC utilizes a smaller particle at a higher pressure and flow rate, many of these issues are remedied. When used in combination with mass spectrometry, UPLC becomes a powerful tool for protein identification, characterization, and quantitation. In this work we show how UPLC/MS can be used to separate and identify intact proteins. PMID:20978979

Croley, Timothy R

2011-01-01

194

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

PubMed

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

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

2003-09-01

195

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

Microsoft Academic Search

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

Ji-Zhou Dong; Serban C Moldoveanu

2004-01-01

196

Comparison of sonic spray lonization with atmospheric pressure chemical lonization as an interface of liquid chromatography-mass spectrometry for the analysis of some local anesthetics  

Microsoft Academic Search

Summary  Sonic spray ionization (SSI) was compared with atmospheric pressure chemical ionization (APCI) as an interface for liquid\\u000a chromatography (LC)-mass spectrometry (MS) for the analysis of some local anesthetics. Peaks at [M+H]+ constituted the base peaks for all compounds by both SSI and APCI, except for prilocaine. The sensitivities by SSI for tetracaine,\\u000a benzoxinate, dibucaine, bupivacaine and mepivacaine were 4–16 times

T. Arinobu; H. Hattori; A. Ishii; T. Kumazawa; X.-P. Lee; O. Suzuki; H. Seno

2003-01-01

197

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

PubMed Central

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

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

2007-01-01

198

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

199

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

PubMed

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

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

2011-05-01

200

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

PubMed

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

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

2010-07-01

201

Enhanced monitoring of biopharmaceutical product purity using liquid chromatography-mass spectrometry.  

PubMed

LC-MS is a widely used technique for impurity detection and identification. It is very informative and generates huge amounts of data. However, the relevant chemical information may not be directly accessible from the raw data map, particularly in reference to applications where unknown impurities are to be detected. This study demonstrates that multivariate statistical process control (MSPC) based on principal component analysis (PCA) in conjunction with multiple testing is very powerful for comprehensive monitoring and detection of an unknown and co-eluting impurity measured with liquid chromatography-mass spectrometry (LC-MS). It is demonstrated how a spiked impurity present at low concentrations (0.05% (w/w)) is detected and further how the contribution plot provides clear diagnostics of the unknown impurity. This tool makes a fully automatic monitoring of LC-MS data possible, where only relevant areas in the LC-MS data are highlighted for further interpretation. PMID:21621780

Laursen, Kristoffer; Justesen, Ulla; Rasmussen, Morten A

2011-05-06

202

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

Microsoft Academic Search

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

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

2001-01-01

203

Liquid chromatography–mass spectrometry: potential in forensic and clinical toxicology  

Microsoft Academic Search

A relatively limited number of papers concerning applications of liquid chromatography–mass spectrometry (LC–MS) to forensic or clinical toxicology, or analytical methods directly applicable to these topics have been published so far, but their number have greatly increased in the past two years, probably due to technical improvements and to a decrease in the price of such instruments. After a brief

P. Marquet; G. Lachâtre

1999-01-01

204

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

Microsoft Academic Search

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

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

1971-01-01

205

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

206

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

Microsoft Academic Search

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

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

2006-01-01

207

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

Microsoft Academic Search

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

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

2009-01-01

208

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

Microsoft Academic Search

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

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

1989-01-01

209

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

Microsoft Academic Search

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

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

2011-01-01

210

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

Microsoft Academic Search

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

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

1995-01-01

211

The use of thermospray-liquid chromatography\\/mass spectrometry for the verification of chemical warfare agents  

Microsoft Academic Search

Thermospray-liquid chromatography mass spectrometry (TSP-LC-MS) is a relatively new analytical technique which proved to be useful for the verification of chemical warfare agents and their polar degradation products in aqueous solutions. The principles of the technique are described and comparisons are made with other forms of mass spectrometric analysis. A survey is presented of the results obtained so far at

E. R. J. Wils; A. G. Hulst

1992-01-01

212

Evaluation of World Anti-Doping Agency criteria for anabolic agent analysis by using comprehensive two-dimensional gas chromatography-mass spectrometry.  

PubMed

This work presents the validation study of the comprehensive two-dimensional gas chromatography (GC x GC)-time-of-flight mass spectrometry method performance in the analysis of the key World Anti-Doping Agency (WADA) anabolic agents in doping control. The relative abundance ratio, retention time, identification and other method performance criteria have been tested in the GC x GC format to confirm that they comply with those set by WADA. Furthermore, tens of other components were identified with an average similarity of >920 (on the 0-999 scale), including 10 other endogenous sterols, and full mass spectra of 5,000+ compounds were retained. The testosterone/epitestosterone ratio was obtained from the same run. A new dimension in doping analysis has been implemented by addressing separation improvement. Instead of increasing the method sensitivity, which is accompanied by making the detector increasingly "blind" to the matrix (as represented by selected ion monitoring mode, high-resolution mass spectrometry (MS) and tandem MS), the method capabilities have been improved by adding a new "separation" dimension while retaining full mass spectral scan information. Apart from the requirement for the mass spectral domain that a minimum of three diagnostic ions with relative abundance of 5% or higher in the MS spectra, all other WADA criteria are satisfied by GC x GC operation. The minimum of three diagnostic ions arises from the need to add some degree of specificity to the acquired mass spectrometry data; however, under the proposed full MS scan method, the high MS similarity to the reference compounds offers more than the required three diagnostic ions for an unambiguous identification. This should be viewed as an extension of the present criteria to a full-scan MS method. PMID:20091298

Mitrevski, Blagoj S; Wilairat, Prapin; Marriott, Philip J

2010-01-21

213

Identification of novel circulating coffee metabolites in human plasma by liquid chromatography–mass spectrometry  

Microsoft Academic Search

This study reports a liquid chromatography–mass spectrometry method for the detection of polyphenol-derived metabolites in human plasma without enzymatic treatment after coffee consumption. Separation of available standards was achieved by reversed-phase ultra performance liquid chromatography and detection was performed by high resolution mass spectrometry in negative electrospray ionization mode. This analytical method was then applied for the identification and relative

Karine Redeuil; Candice Smarrito-Menozzi; Philippe Guy; Serge Rezzi; Fabiola Dionisi; Gary Williamson; Kornél Nagy; Mathieu Renouf

2011-01-01

214

MATRIX EFFECTS IN LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY  

Microsoft Academic Search

Despite their enormous utility and diffusion, atmospheric pressure ionization mass spectrometry techniques are subjected to relevant drawbacks called matrix effects (ME). These effects could be summarized in matrix-dependent signal suppression or enhancement that could lead to erroneous quantitative results. The most important method parameters as well as linearity, precision, and accuracy could be modified due to interfering compounds present in

Achille Cappiello; Giorgio Famiglini; Pierangela Palma; Helga Trufelli

2010-01-01

215

Analytical Variables Affecting Analysis of F2-Isoprostanes and F4-Neuroprostanes in Human Cerebrospinal Fluid by Gas Chromatography/Mass Spectrometry  

PubMed Central

F2-isoprostanes (F2-IsoPs) are a gold marker of lipid peroxidation in vivo, whereas F4-neuroprostanes (F4-NPs) measured in cerebrospinal fluid (CSF) or brain tissue selectively indicate neuronal oxidative damage. Gas chromatography/negative-ion chemical-ionization mass spectrometry (GC/NICI-MS) is the most sensitive and robust method for quantifying these compounds, which is essential for CSF samples because abundance of these compounds in CSF is very low. The present study revealed potential interferences on the analysis of F2-IsoPs and F4-NPs in CSF by GC/NICI-MS due to the use of improper analytical methods that have been employed in the literature. First, simultaneous quantification of F2-IsoPs and F4-NPs in CSF samples processed for F4-NPs analysis could cause poor chromatographic separation and falsely higher F2-IsoPs values for CSF samples with high levels of F2-IsoPs and F4-NPs. Second, retention of unknown substances in GC columns from CSF samples during F4-NPs analysis and from plasma samples during F2-IsoPs analysis might interfere with F4-NPs analysis of subsequent runs, which could be solved by holding columns at a high temperature for a period of time after data acquisition. Therefore, these special issues should be taken into consideration when performing analysis of F2-IsoPs and F4-NPs in CSF to avoid misleading results.

Yen, Hsiu-Chuan; Wei, Hsing-Ju; Chen, Ting-Wei

2013-01-01

216

Determination of capsaicin, dihydrocapsaicin, and nonivamide in self-defense weapons by liquid chromatography–mass spectrometry and liquid chromatography–tandem mass spectrometry  

Microsoft Academic Search

Sensitive and selective liquid chromatography–mass spectrometry (LC–MS) and liquid chromatography–tandem mass spectrometry (LC–MS–MS) methods for the analysis of capsaicin, dihydrocapsaicin, and nonivamide in pepper spray products have been developed. Chromatographic separation of the capsaicinoid analogues was achieved using a reversed-phase HPLC column and a stepwise gradient of methanol and distilled water containing 0.1% (v\\/v) formic acid. Identification and quantification of

Christopher A. Reilly; Dennis J. Crouch; Garold S. Yost; Alim A. Fatah

2001-01-01

217

Liquid chromatography-mass spectrometry identification of imidacloprid photolysis products  

Microsoft Academic Search

Photolysis of imidacloprid by near ultraviolet (UV) radiation was investigated using reversed phase liquid chromatography (RPLC) and liquid chromatography-electrospray ionization\\/mass spectrometry (LC-ESI\\/MS) operated in the positive ion mode. The decomposition of imidacloprid by near UV light is first order with a half life of 10.18h. Photo-degradation products of imidacloprid identified in this study included imidacloprid urea, imidacloprid olefin, and imidacloprid

Tao Ding; David Jacobs; Barry K. Lavine

2011-01-01

218

Simultaneous analysis of oxygenated and nitrated polycyclic aromatic hydrocarbons on standard reference material 1649a (urban dust) and on natural ambient air samples by gas chromatography–mass spectrometry with negative ion chemical ionisation  

Microsoft Academic Search

This study deals with the development of a routine analytical method using gas chromatography–mass spectrometry with negative ion chemical ionisation (GC\\/NICI-MS) for the determination of 17 nitrated polycyclic aromatic hydrocarbons (NPAHs) and 9 oxygenated polycyclic aromatic hydrocarbons (OPAHs) present at low concentrations in the atmosphere. This method includes a liquid chromatography purification procedure on solid-phase extraction (SPE) cartridge. Application of

A. Albinet; E. Leoz-Garziandia; H. Budzinski; E. ViIlenave

2006-01-01

219

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

NASA Astrophysics Data System (ADS)

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

van Keulen, Henk

2009-07-01

220

?-sitosterol in different parts of Saraca asoca and herbal drug ashokarista: Quali-quantitative analysis by liquid chromatography-mass spectrometry  

PubMed Central

?-sitosterol is an important component in food and herbal products and beneficial in hyperlipidemia. Its higher concentrations in serum may lead to coronary artery disease in case of sitosterolemia. Therefore, it is essential to determine the quantity of ?-sitosterol in food and herbal drugs. Saraca asoca and its preparations have been widely used by traditional healers are also a source of ?-sitosterol. In the present study, quantitative estimation of ?-sitosterol present in hot and cold water extracts of bark, regenerated bark, leaves and flowers of the S. asoca and Ashokarista drugs were carried out first time using high performance liquid chromatography coupled (HPLC) with quadrupole time-of-flight mass spectrometry. Different concentrations of ?-sitosterol and crude extracts were estimated by HPLC and targeted mass spectrometry. Standard curve for ?-sitosterol was prepared from the intensities of transitions (397.50 ? 147.0987 m/z) having regression coefficient (r2) 0.9952. Out of eight extracts and two drugs used in the study bark water, leaves water and leaves hot water extracts were found to have a considerable quantity of ?-sitosterol, i.e. 170, 123.5 and 19.3 ng/mL, respectively. The results showed significant differences in the distribution of ?-sitosterol among different organs of S. asoca and drugs prepared from its bark. HPLC/electrospray ionizationmass spectroscopy method is accurate, reproducible and requires less specimen, sample preparation and analysis time over HPLC assay. This type of approaches could be helpful for the quality control of herbal medicines and provides necessary information for the rational utilization of plant resources.

Gahlaut, Anjum; Shirolkar, Amey; Hooda, Vikas; Dabur, Rajesh

2013-01-01

221

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

PubMed

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

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

2005-03-01

222

Pipette tip solid-phase extraction and ultra-performance liquid chromatography/mass spectrometry based rapid analysis of picrosides from Picrorhiza scrophulariiflora.  

PubMed

Pipette tip solid-phase extraction (PT-SPE) is a technique popular in sample preparation of biological fluids and protein hydrolysates. In this study, we developed a microtechnic using a pipette tip packed with C18 as sorbent for extraction and purification of bioactive compounds, picroside-I, II and III, in crude herbal extracts from Picrorhiza scrophulariiflora (P. scrophulariiflora). Compared to conventional SPE, PT-SPE is fast, easy to operate, and the tools are very accessible (pipette tip and tube, without expensive SPE set-up). Moreover, it is also cost-effective because significant amount of sorbent and solvents can be saved. The eluate was analyzed by ultra-performance liquid chromatography and tandem mass spectrometry (UPLC-MS/MS). Afterwards, the method was fully validated and the results demonstrated that the PT-SPE-UPLC-MS/MS method is an excellent technique for analysis of the herbal medicine. Finally, this PT-SPE-UPLC-MS/MS strategy was successfully applied to analyze the crude extracts from P. scrophulariiflora samples within 10min (2min for PT-SPE and 8min for UPLC), 3.5mL solvents (including water, 0.3mL for PT-SPE and 3.2mL for UPLC), and 2mg C18 sorbent for each sample. We believe this method to be very practical and, in particular, to be suitable for widespread herbal medicine analysis. PMID:23567266

Shen, Qing; Dong, Wei; Wang, Yixuan; Gong, Like; Dai, Zhiyuan; Cheung, Hon-Yeung

2013-03-15

223

Application of pyrolysis-gas chromatography-mass spectrometry and multivariate analysis to study bacteria and fungi in biofilms used for bioremediation.  

PubMed

Biofilms are communities of microorganisms adhering to a surface and embedded in an extracellular polymeric matrix, frequently associated with disease and contamination, and also used for engineering applications such as bioremediation. A mixed biofilm formed by bacteria and fungi may provide an optimal habitat for addressing contaminated areas. To exploit the potential of natural microbial communities consisting of bacteria and fungi, it is essential to understand and control their formation. In this work, a method to discriminate among bacteria of genera Bacillus, Pseudomonas, Rhodococcus with respect to the fungus Pleorotus in a biofilm by means of pyrolysis-gaschromatography-mass spectrometry and multivariate analysis is reported. Methylated fatty acids were chosen as biomarkers of microorganisms in the pyrolysates. In situ thermal hydrolysis and methylation was applied. Pyrograms were used as fingerprints, thus allowing for the characterization of whole cells analyzed without any sample pretreatment. Normalized pyrographic peak areas were chosen as variables for chemometric data processing. Principal components analysis was applied as a data exploration tool. Satisfactory results were obtained in analyzing a real biofilm. The influence of growth medium on whole bacteria fatty acid cell composition was also explored. PMID:23721185

Melucci, Dora; Fedi, Stefano; Locatelli, Marcello; Locatelli, Clinio; Montalbani, Simona; Cappelletti, Martina

2013-08-01

224

Parallel analysis of stimulants in saliva and urine by gas chromatography\\/mass spectrometry: Perspectives for “in competition” anti-doping analysis  

Microsoft Academic Search

Stimulants are banned by the World Anti-Doping Agency (WADA) if used “in competition”. Being the analysis of stimulants presently carried out on urine samples only, it might be useful, for a better interpretation of analytical data, to discriminate between an early intake of the substance and an administration specifically aimed to improve the sport performance. The purpose of the study

Sabina Strano-Rossi; Cristiana Colamonici; Francesco Botrè

2008-01-01

225

Automated headspace solid-phase microextraction versus headspace for the analysis of furan in foods by gas chromatography-mass spectrometry.  

PubMed

A simple, fast and fully automated method based on headspace solid-phase microextraction coupled on-line with gas chromatography-ion trap mass spectrometry (HS-SPME-GC-ITMS) is proposed for furan determination in foods. The performance of the proposed method was compared to the automated headspace-GC-MS method, proposed by the US Food and Drugs Administration (US FDA), in terms of repeatability, limits of the detection and quantification. Both methods gave similar results for furan determination in selected food samples, although slightly worse precision (RSD%, 9-12%) and higher limits of detection (from 5 to 20 times higher) were obtained by the headspace method. In addition, higher sample throughput in routine furan analysis was obtained using the proposed HS-SPME-GC-ITMS method with isotope dilution than using the US FDA method, which recommends standard addition for quantification. The proposed method provides good precision (RSD% <10%) and low limits of detection, ranging from 0.02 to 0.12 ng g(-1) depending on the sample. The developed HS-SPME-GC-MS method was used to analyse furan in several Spanish food commodities and concentrations ranging from 0.1 ng g(-1) to 1.1 microg g(-1) were found. PMID:19362194

Altaki, M S; Santos, F J; Galceran, M T

2009-02-10

226

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

Microsoft Academic Search

Liquid chromatography coupled to mass spectrometry (LC-MS) and tandem mass spectrometry (LC-MS\\/MS) has become a standard technique for analyzing complex peptide mixtures to determine composition and relative quantity. Several high-throughput proteomics techniques attempt to combine complementary results from multiple LC-MS and LC-MS\\/MS analyses to provide more comprehensive and accurate results. To effectively collate results from these techniques, variations in mass

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

2006-01-01

227

Improvements in the methodology of monitoring sulfur mustard exposure by gas chromatography-mass spectrometry analysis of cleaved and derivatized blood protein adducts.  

PubMed

An analytical method for determining exposure to 2,2'-dichlorodiethyl sulfide (sulfur mustard, HD) has been enhanced. The method is based on the cleavage of adducted HD (protein-hydroxyethylthioethyl esters) to produce thiodiglycol. Following cleavage, a deuterated internal standard is added, and the analytes are extracted, derivatized, and analyzed by gas chromatography-negative ion chemical ionization-mass spectrometry. Inclusion of a concentration step, addition of solid sodium bicarbonate to neutralize excess derivatization reagent, and optimization of method and instrument conditions provided dramatic increases in signal-to-noise ratio. A five-day precision and accuracy study was conducted, including interday and intraday unknown analysis. Linearity was verified by a R(2) > 0.9995 for all five curves evaluated. The precision and accuracy of the assay were demonstrated to be excellent by evaluation of the interday and intraday unknown samples (< 10% relative standard deviation and relative error in most cases). Statistical treatment of the method blanks and calibration results demonstrated a reduction in the limit of quantitation from 25 nM (HD, human plasma, in vitro) to 1.56 nM. Sample and calibration stability through the analytical sequence was established by the inclusion of continuing calibration verification standards (< 5% error). Short-term sample stability was verified by reinjection of a calibration set after 18 days (R(2) = 0.9997). Quantitative agreement with the previous method was supported by the analysis of a 50 nM standard protein sample (HD, rat plasma) with both methodologies (< 1% error). PMID:18269790

Lawrence, Richard J; Smith, J Richard; Boyd, Brian L; Capacio, Benedict R

228

Classification of High Speed Gas Chromatography-Mass Spectrometry Data by Principal Component Analysis Coupled with Piecewise Alignment and Feature Selection  

SciTech Connect

A useful procedure is introduced for the analysis of data obtained via gas chromatography with mass spectrometry (GC-MS) utilizing a complete mass spectrum at each retention time interval in which a mass spectrum was collected. Principal component analysis (PCA) with preprocessing by both piecewise retention time alignment and analysis of variance (ANOVA) feature selection is applied to all mass channels collected. The procedure involves concatenating all concurrently measured individual m/z chromatograms from m/z 20 to 120 for each GC-MS separation into a row vector. All of the sample row vectors are incorporated into a matrix where each row is a sample vector. This matrix is piecewise aligned and reduced by ANOVA feature selection. Application of the preprocessing steps (retention time alignment and feature selection) to all mass channels collected during the chromatographic separation allows considerably more selective chemical information to be incorporated in the PCA classification, and is the primary novelty of the report. This procedure is objective and requires no knowledge of the specific analytes of interest, as in selective ion monitoring (SIM), and does not restrict the mass spectral data used, as in both SIM and total ion current (TIC) methods. Significantly, the procedure allows for the classification of data with low resolution in the chromatographic dimension because of the added selectivity from the complete mass spectral dimension. This allows for the successful classification of data over significantly decreased chromatographic separation times, since high-speed separations can be employed. The procedure is demonstrated through the analysis of a set of four differing gasoline samples that serve as model complex samples. For comparison, the gasoline samples are analyzed by GC-MS over both ten-minute and ten-second separation times. The ten-minute GC-MS TIC data served as the benchmark analysis to compare to the ten-second data. When only alignment and feature selection was applied to the ten-second gasoline separations using GC-MS TIC data, PCA failed. PCA was successful for ten-second gasoline separations when the procedure was applied with all the m/z information. With ANOVA feature selection, chromatographic regions with Fisher Ratios greater than 1500 were retained in a new matrix and subjected to PCA yielding successful classification for the ten-second separations.

Watson, Nathaniel E.; VanWingerden, Matthew M.; Pierce, Karisa M.; Wright, Bob W.; Synovec, Robert E.

2006-09-01

229

Extraction of pesticides, dioxin-like PCBs and PAHs in water based commodities using liquid-liquid microextraction and analysis by gas chromatography-mass spectrometry.  

PubMed

Water based samples such as flavored drinks, juices and drinking water may contain contaminants at ultra trace level belonging to different chemical classes. A novel, simple, low-cost and fast method was developed and validated for trace residue extraction of pesticides, dioxin-like PCBs and PAHs from water and water based samples followed by analysis through gas chromatography (GC) coupled with time-of-flight mass spectrometry (ToFMS). The extraction solvent type, volume; sample volume and other extraction conditions were optimized. This was achieved by extracting 10 mL sample with 250 ?L chloroform by vortexing (1 min, standing time of 2 min) followed by centrifugation (6000 rpm, 5 min). The bottom organic layer (200 ?L) was pipetted out, evaporated to near dryness and reconstituted in 20 ?L of ethyl acetate+cyclohexane (1:9) mixture resulting in an enrichment factor of 400. The recoveries of all compounds were within 76-120% (±10%) with the method detection limit (MDL) ranging from 1 to 250 ng/L depending on the analyte response. The MDLs were 400 times lower than the instrument quantification limits that ranged from 0.4 to 100 ng/mL. The method was further validated in water based drinks (e.g. apple, lemon, pineapple, orange, grape and pomegranate juice). For the juices with suspended pulp, the extraction was carried out with 400 ?L chloroform. The extract was analyzed by GC-ToFMS at both 1D and GC×GC modes to chromatographically separate closely eluting interfering compounds the effect of which could not be minimized otherwise. The resulting peak table was filtered to identify a range of compounds belonging to specific classes viz. polycyclic aromatic hydrocarbons, chlorinated, brominated, and nitro compounds. User developed scripts were employed on the basis of identification of the molecular ion and isotope clusters or other spectral characteristics. The method performed satisfactorily in analyzing both incurred as well as market samples. PMID:21820665

Dasgupta, Soma; Banerjee, Kaushik; Utture, Sagar; Kusari, Parijat; Wagh, Sameer; Dhumal, Kondiba; Kolekar, Sanjay; Adsule, Pandurang G

2011-07-23

230

Analysis of 4-aminobiphenyl-DNA adducts in human urinary bladder and lung by alkaline hydrolysis and negative ion gas chromatography-mass spectrometry.  

PubMed Central

Analysis of carcinogen-DNA adducts has been regarded as a useful means of assessing human exposure to chemical carcinogens. We have established a method for quantitation of 4-aminobiphenyl (4-ABP)-DNA adducts by alkaline hydrolysis and gas chromatography with negative ion chemical ionization mass spectrometry (GC-NICI-MS). Aliquots of DNA (typically 100 micrograms/ml) were spiked with an internal standard, d9-4-ABP, and were hydrolyzed in 0.05 N NaOH at 130 degrees C overnight. The liberated 4-ABP was extracted with hexane and derivatized using pentafluoropropionic anhydride in trimethylamine for 30 min at room temperature prior to GC-NICI-MS. With in vitro [3H]N-hydroxy-4-ABP modified DNA standards, we observed 59 +/- 7% (n = 9) recovery of the 4-ABP and a linear correlation between hydrolyzed 4-ABP and the adduct levels ranging from about 1 in 10(8) to 1 in 10(4) nucleotides (r = 0.999, n = 9). The method was further validated by comparison of the results with that obtained by the 32P-postlabeling method. There was excellent agreement (r = 0.994, p < 0.001) between the two methods for quantitation of the adduct in eight samples of Salmonella typhimurium DNA treated with 4-ABP and rat liver S9, although the 32P-postlabeling method gave slightly higher values. The DNA adducts in 11 human lung and 8 urinary bladder mucosa specimens were then determined by our GC-NICI-MS method. The adduct levels were found to be < 0.32 to 49.5 adducts per 10(8) nucleotides in the lungs and < 0.32 to 3.94 adducts per 10(8) nucleotides in the bladder samples.(ABSTRACT TRUNCATED AT 250 WORDS) Images Figure 4. A Figure 4. B

Lin, D; Lay, J O; Bryant, M S; Malaveille, C; Friesen, M; Bartsch, H; Lang, N P; Kadlubar, F F

1994-01-01

231

A liquid chromatography-mass spectrometry approach to study "glucosinoloma" in broccoli sprouts.  

PubMed

Glucosinolates are an important class of secondary plant metabolites, possessing health-promoting properties. Young broccoli plants are a very good source of glucosinolates with concentrations several times greater than in mature plants. The aim of our study was to develop a liquid chromatography-mass spectrometry and liquid chromatography/tandem mass spectrometry qualitative and quantitative method for the measure of glucosinolates in broccoli sprouts. The described method provides high sensitivity and specificity, allowing a rapid and simultaneous determination of 14 glucosinolates. The proposed method has been validated for eight glucosinolates: glucobrassicin, glucoraphanin, glucoiberin, glucoerucin, progoitrin, gluconapin, sinigrin and glucocheirolin. The linear range was 1-150 µg ml(-1), the intra-day and inter-day precision values are within 6% and 8% at the lower limit of quantification, while the overall recovery of the eight glucosinolates was 99?±?9%. This validated method was used successfully for analysis of glucosinolates content of broccoli sprouts grown in different conditions. PMID:22972788

Maldini, Mariateresa; Baima, Simona; Morelli, Giorgio; Scaccini, Cristina; Natella, Fausta

2012-09-01

232

Determination of cocaine in postmortem human liver exposed to overdose. Application of an innovative and efficient extraction/clean up procedure and gas chromatography-mass spectrometry analysis.  

PubMed

A simple and efficient method was developed for the determination of cocaine in post-mortem samples of human liver via solid-liquid extraction with low temperature partitioning (SLE-LTP) and analysis by gas chromatography coupled to mass spectrometry (GC-MS). The extraction procedure was optimized by evaluating the influence of the following variables: pH of the extract, volume and composition of the extractor solvent, addition of a sorbent material (PSA: primary-secondary amine) and NaCl to clean up and increase the ionic strength of the extract. A bovine liver sample that was free of cocaine was used as a blank for the optimization of the SLE-LTP extraction procedure. The highest recovery was obtained when crushed bovine liver (2g) was treated with 2mL of ultrapure water plus 8mL of acetonitrile at physiological pH (7.4). The results also indicated no need for using PSA and NaCl. The complete analytical procedure was validated for the following figures of merit: selectivity, lower limit of quantification (LLOQ), calibration curve, recovery, precision and accuracy (for within-run and between-run experiments), matrix effect, dilution integrity and stability. The within-run and between-run precision (at four levels) varied from 2.1% to 9.4% and from 4.0% to 17.0%, respectively. A maximum deviation of 11.62% for the within-run and between-run accuracies in relation to the nominal concentrations was observed. Moreover, the LLOQ value for cocaine was 50.0ngg(-1) whereas no significant effects were noticed in the assays of dilution integrity and stability. To assess its overall performance, the optimized method was applied to the analysis of eight human liver samples collected from individuals who died due to the abusive consumption of cocaine. Due to the existence of a significant matrix effect, a blank human liver was used to construct a matrix-matched analytical curve. The concentrations of cocaine found in these samples ranged from 333.5 to 5969ngg(-1). PMID:23972460

Magalhães, Elisângela Jaqueline; Queiroz, Maria Eliana Lopes Ribeiro de; Penido, Marcus Luiz de Oliveira; Paiva, Marco Antônio Ribeiro; Teodoro, Janaína Aparecida Reis; Augusti, Rodinei; Nascentes, Clésia Cristina

2013-08-15

233

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

Microsoft Academic Search

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

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

1995-01-01

234

QUANTIFICATION OF CILNIDIPINE IN HUMAN PLASMA BY LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY  

Microsoft Academic Search

A liquid chromatography-mass spectrometry (LC-MS) assay was developed and validated for the quantification of cilnidipine, a calcium channel antagonist, in human plasma. Plasma samples were processed by liquid-liquid extraction and the analyte, along with nimodipine (an internal standard), and analyzed using selected ion monitoring (SIM) for detection. The absolute extraction recovery was determined to be not less than 89.1% for

Kyeong-Ryoon Lee; Yoon-Jee Chae; Jong-Hwa Lee; Dae-Duk Kim; Saeho Chong; Chang-Koo Shim; Suk-Jae Chung

2012-01-01

235

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

236

A liquid chromatography-mass spectrometry-based metabolome database for tomato  

Microsoft Academic Search

For the description of the metabolome of an organism, the development of common metabolite databases is of utmost importance. Here we present the Metabolome Tomato Database (MoTo DB), a metabolite database dedicated to liquid chromatography-mass spectrometry (LC-MS)- based metabolomics of tomato fruit (Solanum lycopersicum). A reproducible analytical approach consisting of reversed-phase LC coupled to quadrupole time-of-flight MS and photodiode array

Sofia Moco; Raoul J. Bino; Oscar Vorst; Harrie A. Verhoeven; Groot de J. C. W; Beek van T. A; J. J. M. Vervoort; Vos de C. H

2006-01-01

237

Contributions of liquid chromatography–mass spectrometry to “highlights” of biomedical research  

Microsoft Academic Search

Combined chromatographic and mass spectrometric techniques and in particular liquid chromatography–mass spectrometry (LC–MS) have been contributing in a decisive way to the progress of life sciences in general. Thus, the number of document entries in the US National Library of Medicine (MEDLINE) for articles dealing with LC–MS was 738 in 1991 and 2285 in 2001, with a total of 13?147

Emilio Gelp??

2003-01-01

238

Effect of eluent on the ionization process in liquid chromatography–mass spectrometry  

Microsoft Academic Search

The most widely used ionization techniques in liquid chromatography–mass spectrometry (LC–MS) are electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI). All three provide user friendly coupling of LC to MS. Achieving optimal LC–MS conditions is not always easy, however, owing to the complexity of ionization processes and the many parameters affecting mass spectrometric sensitivity and

Risto Kostiainen; Tiina J. Kauppila

2009-01-01

239

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

Microsoft Academic Search

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

Bruce W. Patterson; Guohong Zhao; Samuel Klein

1998-01-01

240

Determination of amprolium in feed by a liquid chromatography–mass spectrometry method  

Microsoft Academic Search

As a consequence of the finding of veterinarian drugs in food European Community banned several compounds like coccidiostats as amprolium (APL). This antibiotic has been used as a preventive and clinical anticoccidial drug in chicken. The 2005\\/187\\/CE, 2005\\/925\\/EC Recommendations ban the use of amprolium as additive in chicken feed. For this reason a rapid and sensitive liquid chromatography–mass spectrometry (LC–MS)

S. Squadrone; C. Mauro; G. L. Ferro; G. Amato; M. C. Abete

2008-01-01

241

Multi-atmospheric pressure ionisation interface for liquid chromatography–mass spectrometry  

Microsoft Academic Search

We describe the structure of a multi-atmospheric pressure ionisation (multi-API) interface for liquid chromatography–mass spectrometry (LC–MS). This interface includes five modes of atmospheric pressure spray with electron impact ionisation (APEI), atmospheric pressure chemical ionisation (APCI), atmospheric pressure spray ionisation (APSI), electrospray ionisation (ESI) and sonic spray ionisation (SSI). This LC–MS system was realised by developing an APEI interface which resembles

Minoru Sakairi; Yoshiaki Kato

1998-01-01

242

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

Microsoft Academic Search

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

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

2000-01-01

243

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

Microsoft Academic Search

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

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

2005-01-01

244

Liquid chromatography–mass spectrometry (LC–MS) of steroid hormone metabolites and its applications  

Microsoft Academic Search

Advances in liquid chromatography–mass spectrometry (LC–MS) can be used to measure steroid hormone metabolites in vitro and in vivo. We find that LC–electrospray ionization (ESI)-MS using a LCQ ion trap mass spectrometer in the negative ion mode can be used to monitor the product profile that results from 5?-dihydrotestosterone (DHT)-17?-glucuronide, DHT-17?-sulfate, and tibolone-17?-sulfate reduction catalyzed by human members of the

Trevor M. Penning; Seon-Hwa Lee; Yi Jin; Alejandro Gutierrez; Ian A. Blair

2010-01-01

245

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

Microsoft Academic Search

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

A. S Pereira; F. R Aquino Neto

1999-01-01

246

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

Microsoft Academic Search

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

Arndt Asperger; Werner Engewald; Gerd Fabian

1999-01-01

247

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

Microsoft Academic Search

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

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

2004-01-01

248

Determination of fluoroquinolone antibiotics in wastewater effluents by liquid chromatography–mass spectrometry and fluorescence detection  

Microsoft Academic Search

The occurrence of quinolone antibiotics (QAs) was investigated in wastewater effluents and surface river\\/lake waters in the US and Canada by using solid-phase extraction with mixed phase cation exchange disk cartridge and liquid chromatography–mass spectrometry (LC–MS) and liquid chromatography fluorescence detection (LC-FLD). Ofloxacin (OFL) was detected in secondary and final effluents of a wastewater treatment plant (WWTP) in East Lansing,

Haruhiko Nakata; Kurunthachalam Kannan; Paul D. Jones; John P. Giesy

2005-01-01

249

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

Microsoft Academic Search

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

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

1997-01-01

250

State-of-the-art in liquid chromatography–mass spectrometry  

Microsoft Academic Search

Impressive progress has been made in the technology and application of combined liquid chromatography–mass spectrometry (LC–MS) in the past decennium. From a technique, that could only be used by a specialist, it has developed into a routinely applicable technique. LC–MS has become the method-of-choice of analytical support in many stages of drug development within pharmaceutical industries and has found its

W. M. A Niessen

1999-01-01

251

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

Microsoft Academic Search

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

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

1998-01-01

252

Factors That Contribute to Assay Variation in Quantitative Analysis of Sex Steroid Hormones Using Liquid and Gas Chromatography-Mass Spectrometry  

ERIC Educational Resources Information Center

The list of physiological events in which sex steroids play a role continues to increase. To decipher the roles that sex steroids play in any condition requires high quality cohorts of samples and assays that provide highly accurate quantitative measures. Liquid and gas chromatography coupled with mass spectrometry (LC-MS and GC-MS) have…

Xu, Xia; Veenstra, Timothy D.

2012-01-01

253

Factors That Contribute to Assay Variation in Quantitative Analysis of Sex Steroid Hormones Using Liquid and Gas Chromatography-Mass Spectrometry  

ERIC Educational Resources Information Center

|The list of physiological events in which sex steroids play a role continues to increase. To decipher the roles that sex steroids play in any condition requires high quality cohorts of samples and assays that provide highly accurate quantitative measures. Liquid and gas chromatography coupled with mass spectrometry (LC-MS and GC-MS) have…

Xu, Xia; Veenstra, Timothy D.

2012-01-01

254

Stir bar sorptive extraction with in situ derivatization and thermal desorption-gas chromatography-mass spectrometry for trace analysis of methylmercury and mercury(II) in water sample.  

PubMed

A method for the trace analysis of methylmercury (MeHg) and Hg(II) in water sample was developed, which involved stir bar sorptive extraction (SBSE) with in situ alkylation with sodium tetraethylborate and thermal desorption (TD)-gas chromatography-mass spectrometry (GC-MS). The limits of quantification of MeHg and Hg(II) are 20 and 10 ng L(-1) (Hg), respectively. The method shows good linearity and the correlation coefficients are higher than 0.999. The average recoveries of MeHg and Hg(II) in tap or river water sample are 102.1-104.3% (R.S.D.: 7.0-8.9%) and 105.3-106.2% (R.S.D.: 7.4-8.5%), respectively. This simple, accurate, sensitive, and selective analytical method may be used in the determination of trace amounts of MeHg and Hg(II) in tap and river water samples. PMID:19084638

Ito, Rie; Kawaguchi, Migaku; Sakui, Norihiro; Okanouchi, Noriya; Saito, Koichi; Seto, Yasuo; Nakazawa, Hiroyuki

2008-09-11

255

Determination of organic priority pollutants and emerging compounds in wastewater and snow samples using multiresidue protocols on the basis of microextraction by packed sorbents coupled to large volume injection gas chromatography-mass spectrometry analysis.  

PubMed

This paper describes the development and validation of a new procedure for the simultaneous determination of 41 multi-class priority and emerging organic pollutants in water samples using microextraction by packed sorbent (MEPS) followed by large volume injection-gas chromatography-mass spectrometry (LVI-GC-MS). Apart from method parameter optimization the influence of humic acids as matrix components on the extraction efficiency of MEPS procedure was also evaluated. The list of target compounds includes polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), phthalate esters (PEs), nonylphenols (NPs), bisphenol A (BPA) and selected steroid hormones. The performance of the new at-line microextraction-LVI-GC-MS protocol was compared to standard solid-phase extraction (SPE) and LVI-GC-MS analysis. LODs for 100 mL samples (SPE) ranged from 0.2 to 736 ng L(-1) were obtained. LODs for 800 microL of sample (MEPS) were between 0.2 and 266 ng L(-1). In the case of MEPS methodology even a sample volume of only 800 microL allowed to detect the target compounds. These results demonstrate the high sensitivity of both procedures which permitted to obtain good recoveries (>75%) for all cases. The precision of the methods, calculated as relative standard deviation (RSD) was below 21% for all compounds and both methodologies. Finally, the developed methods were applied to the determination of target analytes in various samples, including snow and wastewater. PMID:20719318

Prieto, A; Schrader, S; Moeder, M

2010-08-03

256

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

PubMed

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

Lavagnini, Irma; Urbani, Alessandro; Magno, Franco

2010-12-13

257

Determination of N-nitrosodiethanolamine in cosmetic products by headspace solid phase microextraction using a novel aluminum hydroxide grafted fused silica fiber followed by gas chromatography-mass spectrometry analysis.  

PubMed

A method based on headspace solid phase microextraction with a new fiber, coupled with gas chromatography-mass spectrometry was developed for the determination of NDELA in cosmetic samples. The fiber provides Lewis acid-base interaction between its surface and analyte functional groups. The fiber was prepared by grafting aluminum tri-tert-butoxide on the surface of a fused silica. The optimization of SPME conditions showed that NDELA can be most effectively extracted at 70°C, in 15 min, with a sample volume of 0.5 (Vs/Vt), stirring rate of 150 rpm, desorption time of 5 min, desorption temperature of 260°C and at 12.5% (w/w) concentration of NaCl. Under the optimized conditions, LOD of 1 ?g Kg(-1) and a calibration curve with correlation coefficients greater than 0.9897 and a linearity range from 6 to 10000 ?g Kg(-1) were obtained. The intra-day and inter-day precision and accuracy were evaluated at four concentration levels. All of the values for accuracy and precision were lower than the acceptable limit of 15%. The fiber to fiber repeatability was 8.7%. The method was applied for the analysis of real samples including hair shampoo, body shampoo, dishwashing liquid and hand washing liquid. Relative recoveries were achieved in the range of 95-99%. PMID:23598029

Davarani, Saied Saeed Hosseiny; Masoomi, Leila; Banitaba, Mohammad Hossein; Zhad, Hamid Reza Lotfi Zadeh; Sadeghi, Omid; Samiei, Azam

2012-10-26

258

Evaluation of the solid-phase extraction (SPE) cartridge method in combination with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) for the analysis of different VOCs in liquid matrices in varying pH conditions.  

PubMed

In this study, the solid-phase extraction (SPE) method combined with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) method is evaluated for the analysis of liquid-phase volatile organic compounds (LVOCs). Calibration experiments were performed on a number of polar and nonpolar LVOCs (including aromatic compounds, ester, ketones, and alcohol) as a function of solution pH. If the relative sensitivity of the SPE-TD-GC-MS method is compared between different VOCs across a wide range of pH (1, 4, 7, 10, and 13), optimum sensitivities for most VOCs are derived at the neutral pH. However, there were some exceptions to the general trend with the maximum sensitivity occurring either at a moderately basic pH (methyl isobutyl ketone and butyl acetate) or extremely acidic conditions (isobutyl alcohol). It was also noticed that the relative ordering of sensitivity was changed, as the pH conditions of the solution vary. The use of internal standard (IS: chlorobenzene) resulted in a notable improvement in both relative sensitivity and reproducibility for most compounds. PMID:22865756

Pandey, Sudhir Kumar; Kim, Ki-Hyun

2012-08-01

259

Advanced Capillary Liquid Chromatography-Mass Spectrometry for Proteomics  

SciTech Connect

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

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

2009-02-23

260

Rapid screening of destruxins by liquid chromatography/mass spectrometry.  

PubMed

A liquid chromatographic/mass spectrometric (LC/MS) method utilizing an atmospheric pressure chemical ionization (APCI) interface and in-source collisionally induced dissociation (CID) was developed for the rapid screening of the cyclic hexadepsipeptides destruxins, produced by the fungi Metarhizium anisopliae and Trichothecium roseum. The APCI mass spectra are fully consistent with the high-energy CID data but the sequence ions are abundant over the whole mass range. In addition to 22 known destruxins, two new representatives of this family were detected by LC/MS analysis: destruxin Ed1 and roseotoxin A were isolated and their structures were inferred from MS/MS and NMR data. PMID:9538526

Jegorov, A; Havlícek, V; Sedmera, P

1998-03-01

261

Liquid Chromatography-Mass Spectrometry of Nucleic Acids  

Microsoft Academic Search

\\u000a By virtue of its high-resolving capability, short analysis time, and advanced instrumentation high-performance liquid chromatography\\u000a (HPLC) has become a versatile technique for the separation and characterization of nucleic acids. Among the various chromatographic\\u000a modes, which have been summarized in several reviews (1–6), ion-pair reversed-phase HPLC (IP-RPHPLC) represents the most popular chromatographic technique applicable to the separation\\u000a of single-and double-stranded DNA

Herbert Oberacher; Walther Parson

262

An introduction to liquid chromatography-mass spectrometry instrumentation applied in plant metabolomic analyses.  

PubMed

Over the past decade the application of non-targeted high-throughput metabolomic analysis within the plant sciences has gained ever increasing interest and has truly established itself as a valuable tool for plant functional genomics and studies of plant biochemical composition. Whilst proton nuclear magnetic resonance ((1)H-NMR) spectroscopy is particularly appropriate for the analysis of bulk metabolites and gas chromatography mass spectrometry (GC-MS) to the analysis of volatile organic compounds (VOC's) and derivatised primary metabolites, liquid chromatography (LC)-MS is highly applicable to the analysis of a wide range of semi-polar compounds including many secondary metabolites of interest to plant researchers and nutritionists. In view of the recent developments in the separation sciences, leading to the advent of ultra high performance liquid chromatography (UHPLC) and MS based technology showing the ever improving resolution of metabolite species and precision of mass measurements (sub-ppm accuracy now being achievable), this review sets out to introduce the background and update the reader upon LC, high performance (HP)LC and UHPLC, as well as the large range of MS instruments that are being applied in current plant metabolomic studies. As well as covering the theory behind modern day LC-MS, the review also discusses the most relevant metabolomics applications for the wide range of MS instruments that are currently being applied to LC. PMID:19927296

Allwood, J William; Goodacre, Royston

263

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

PubMed

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

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

2005-09-01

264

A rapid method for analysis of abscisic acid (ABA) in crude extracts of water stressed Arabidopsis thaliana plants by liquid chromatography—mass spectrometry in tandem mode  

Microsoft Academic Search

We describe a quick, simple method for the extraction and quantification of the phytohormone (+)-abscisic acid (ABA) in samples of plants subjected to different water deficit treatments. The method includes an extraction with acetone\\/water\\/acetic acid (80:19:1, v\\/v), evaporation of the extracts and finally injection into the liquid chromatography-electrospray ionization tandem mass spectrometry (LC–ESI–MS–MS) system in multiple reaction monitoring (MRM) mode.

Marta López-Carbonell; Olga Jáuregui

2005-01-01

265

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

PubMed

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

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

2002-01-01

266

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

267

High-sensitivity analysis of buprenorphine, norbuprenorphine, buprenorphine glucuronide, and norbuprenorphine glucuronide in plasma and urine by liquid chromatography-mass spectrometry.  

PubMed

A new method using ultra-fast liquid chromatography and tandem mass spectrometry (UFLC-MS/MS) was developed for the simultaneous determination of buprenorphine and the metabolites norbuprenorphine, buprenorphine-3?-glucuronide, and norbuprenorphine-3?-glucuronide in plasma and urine. Sample handling, sample preparation and solid-phase extraction procedures were optimized for maximum analyte recovery. All four analytes of interest were quantified by positive ion electrospray ionization tandem mass spectrometry after solid-phase microextraction. The lower limits of quantification in plasma were 1pg/mL for buprenorphine and buprenorphine glucuronide, and 10pg/mL for norbuprenorphine and norbuprenorphine glucuronide. The lower limits of quantitation in urine were 10pg/mL for buprenorphine, norbuprenorphine and their glucuronides. Overall extraction recoveries ranged from 68-100% in both matrices. Interassay precision and accuracy was within 10% for all four analytes in plasma and within 15% in urine. The method was applicable to pharmacokinetic studies of low-dose buprenorphine. PMID:24095872

Regina, Karen J; Kharasch, Evan D

2013-09-08

268

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

PubMed

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

Dissanayake, Shamitha; Lathan, Patty; Mlsna, Todd

2012-09-18

269

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

PubMed

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

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

2012-11-16

270

Free flow electrophoresis coupled with liquid chromatography–mass spectrometry for a proteomic study of the human cell line (K562\\/CR3)  

Microsoft Academic Search

The requirement for prefractionation in proteomic analysis is linked to the challenge of performing such an analysis on complex biological samples and identifying low level components in the presence of numerous abundant housekeeping and structural proteins. The employment of a preliminary fractionation step results in a reduction of complexity in an individual fraction and permits more complete liquid chromatography\\/mass spectrometry

Yonghui Wang; William S. Hancock; Gerhard Weber; Christoph Eckerskorn; Darryl Palmer-Toy

2004-01-01

271

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

272

Liquid chromatography-mass spectrometry analysis of macranthoidin B, macranthoidin A, dipsacoside B, and macranthoside B in rat plasma for the pharmacokinetic investigation.  

PubMed

A liquid chromatography-electrospray ionization-mass spectrometry method has been developed and validated for identification and quantification of four major bioactive saponins in rat plasma after oral administration of extraction of saponins from Flos Lonicerae, i.e., macranthoidin B, macranthoidin A, dipsacoside B, and macranthoside B. Plasma samples were extracted with solid-phase extraction, separated on a Shim-pack CLC-ODS column and detected by MS in negative selective ion monitoring mode. Calibration curves offered linear ranges of two orders of magnitude with r(2)>0.999. The method showed the low limit quantification of 7.72, 6.06, 7.16, and 1.43 ng/mL for macranthoidin B, macranthoidin A, dipsacoside B, and macranthoside B, respectively. The inter- and intra-CV precision (R.S.D.) were all within 10% and accuracy (% bias) ranged from -10 to 10%. The overall recovery was more than 70%. This developed method was subsequently successfully applied to pharmacokinetic profiles of the four saponins in rats. After oral administration of extraction of saponins in rats, the concentration-time course was found to be the double peaks of curve. PMID:19097951

Chen, Chun-Yun; Qi, Lian-Wen; Yi, Ling; Li, Ping; Wen, Xiao-Dong

2008-12-06

273

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

PubMed

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

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

2013-03-13

274

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

PubMed

F2-Isoprostanes (IsoPs) are isomers of prostaglandin F2? formed from the nonenzymatic free radical-catalyzed peroxidation of arachidonic acid. Since discovery of these molecules by Morrow and Roberts in 1990, F2-IsoPs have been shown to be excellent biomarkers as well as potent mediators of oxidative stress in vivo in humans. Isofurans (IsoFs) are also oxidation products generated from the nonenzymatic oxidation of arachidonic acid. IsoFs are preferentially formed instead of F2-IsoPs in settings of increased oxygen tension. The protocol presented herein is the current methodology that our laboratory uses to quantify F2-IsoPs and IsoFs in biological tissues and fluids using gas chromatography/mass spectrometry (GC/MS). A variety of analytical procedures to measure F2-IsoPs, including other GC/MS methods and liquid chromatography/MS and immunological approaches, are reported in the literature. This method provides a very low limit of quantitation and is suitable for analysis of both F2-IsoPs and IsoFs from a variety of biological sources including urine, plasma, tissues, cerebral spinal fluid, exhaled breath condensate, and amniotic fluid, among others. PMID:23044261

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

2012-10-05

275

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

PubMed

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

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

2005-01-01

276

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

PubMed

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

Hardt, J; Angerer, J

277

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

PubMed

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

Baumer, Ursula; Dietemann, Patrick

2010-03-30

278

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

PubMed

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

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

2010-06-24

279

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

SciTech Connect

A thermal extraction cone penetrometry gas chromatography/mass spectrometry system (TECP GC/MS) has been developed to detect subsurface contaminants in situ. The TECP can collect soil-bound organics up to depths of 30 m. In contrast to traditional cone penetrometer sample collectors, the TECP extracts organics from soil without bringing the soil to the surface or into a collection chamber. Results show that polychlorinated biphenyls, polycyclic aromatic hydrocarbons (PAHs), chlorinated pesticides, and explosives can be recovered (60--95%) from wet or dry soil, with extraction efficiency compound-specific. The data are in remarkable agreement with closed cell thermal desorption (TD) experiments, where no organics are lost to the environment during heating. ECP GC/MS results also compare favorably with solvent-extracted GC/MS analyses and can be used to delineate the presence and extent of contamination at hazardous waste sites. Data illustrating TECP dependence on probe temperature and soil moisture as well as carrier gas liner velocity and volume (modified Reynolds number) are shown along with sample analysis data from two hazardous waste sites. The total ion and reconstructed ion current chromatograms are shown for PAHs collected by TECP from a coal tar contaminated soil obtained at a manufactured gas plant in Massachusetts. TECP and TD results are within 15% for nonvolatile PAHs and within 50% of the solvent-extracted data.

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

1999-07-15

280

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

PubMed

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

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

2009-02-11

281

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

PubMed

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

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

2012-06-12

282

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

PubMed Central

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

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

2013-01-01

283

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

PubMed

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

Haglock, Carrie; Wolf, Carl; Poklis, Alphonse

2008-10-01

284

Quantification of veterinary antibiotics (sulfonamides and trimethoprim) in animal manure by liquid chromatography-mass spectrometry.  

PubMed

A fast and cost effective method was developed to extract and quantify residues of veterinary antimicrobial agents (antibiotics) in animal manure by liquid-liquid extraction and liquid chromatography-mass spectrometry. The compounds investigated include six sulfonamides, one metabolite, and trimethoprim. The method was performed without sample clean up. Recoveries from spiked manure slurry samples (spike level = 1 mg/kg) were as follows: sulfaguanidine (52%), sulfadiazine (47%), sulfathiazole (64%), sulfamethazine (89%), its metabolite N4-acetyl-sulfamethazine (88%), sulfamethoxazole (84%), sulfadimethoxine (51%), and trimethoprim (64%). Relative standard deviations of the recoveries were less than 5% within the same day and less than 20% between days. The limit of quantification was below 0.1 mg/kg liquid manure slurry for all compounds and calibration curves obtained from extracts of spiked samples were linear up to a level of 5 mg/kg liquid manure, except for trimethoprim (0.01-0.5 mg/kg). Analysis of six grab samples taken in Switzerland from manure pits on farms where medicinal feed had been applied revealed total sulfonamide concentrations of up to 20 mg/kg liquid manure. PMID:12064522

Haller, Michel Y; Müller, Stephan R; McArdell, Christa S; Alder, Alfredo C; Suter, Marc J F

2002-04-01

285

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

PubMed

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

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

2013-05-13

286

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

EPA Science Inventory

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

287

Open-access liquid chromatography/mass spectrometry in a drug discovery environment.  

PubMed

The use of open-access mass spectrometry to monitor synthetic chemistry reactions, and also the integrity and purity of new chemical entities, has been a part of the medicinal chemist's tool-box for more than 5 years. Originally in our group at Wyeth Research there were two open-access methods available to the chemists, flow injection analysis (FIA) and liquid chromatography/mass spectrometry (LC/MS). The FIA method was approximately 3 min long, while the LC/MS method was approximately 20 min long (including an 8 min gradient). Within the first 2 years, the total number of open-access analyses increased by approximately 125%. It is interesting, however, that the number of LC/MS analyses increased by more than 285%. This is attributed to the fact that the chemists began using the LC/MS data to monitor reactions and also to check final product integrity and purity. In addition, the number of chemists performing parallel synthesis reactions has increased; thus, individual chemists can produce sample sets of up to 100 vials. This paper describes the implementation of new methodology, which accommodates the need for much faster run times and also the ability to acquire alternating positive and negative ion spectra within the same run. In addition, the instrument has been configured to e-mail the resulting processed data report to the submitting chemist. Several methods have been developed, including structure elucidation using in-source collision-induced dissociation (CID) and night-time analysis. The LC/MS methods for this system are described herein and are applicable to both industrial and academic synthetic chemistry optimization efforts. PMID:12271431

Mallis, Larry M; Sarkahian, Ani B; Kulishoff, John M; Watts, William L

2002-09-01

288

Comparative Analysis of Polychlorinated Dibenzo-'p'-dioxin and Dibenzofuran Congeners in Great Lakes Fish Extracts by Gas Chromatography-Mass Spectrometry and In vitro Enzyme Induction Activities.  

National Technical Information Service (NTIS)

The high-resolution gas chromatographic-mass spectrometric analysis of 25 Great Lakes fish extracts confirmed the identities of several 2,3,7,8-tetrasubstituted polychlorinated dibenzofurans (PCDFs) and dibenzo-p-dioxins (PCDDs). The dominant congener in ...

T. Zacharewski L. Safe S. Safe B. Chittim D. DeVault

1989-01-01

289

Trace analysis of the antineoplastics ifosfamide and cyclophosphamide in sewage water by twostep solid-phase extraction and gas chromatography-mass spectrometry  

Microsoft Academic Search

A sensitive, specific and highly reproducible method for the analysis of the two antineoplastics, ifosfamide and cyclophosphamide, in sewage water at the ppt-level is presented. The method includes a two-step solid-phase extraction (SPE) on C18 and SiOH material and GC-MS analysis using single ion monitoring (SIM). The method was applied to degradational studies of the two drugs in laboratory-scale sewage

Thomas Steger-Hartmann; Klaus Kümmerer; Jörn Schecker

1996-01-01

290

COMPARATIVE ANALYSIS OF POLYCHLORINATED DIBENZO-P-DIOXIN AND DIBENZOFURAN CONGENERS IN GREAT LAKES FISH EXTRACTS BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY AND IN VITRO ENZYME INDUCTION ACTIVITIES  

EPA Science Inventory

The high-resolution gas chromatographic-mass spectrometric analysis of 25 Great Lakes fish extracts confirmed the identities of several 2,3,7,8-tetrasubstituted polychlorinated dibenzofurans (PCDFs) and dibenzo-p-dioxins (PCDDs). The dominant congener in extracts from Lake Michig...

291

Derivatisation using m-(trifluoromethyl)phenyltrimethylammonium hydroxide of organic materials in artworks for analysis by gas chromatography-mass spectrometry: unusual reaction products with alcohols.  

PubMed

The quaternary ammonium reagent m-(trifluoromethyl)phenyltrimethylammonium hydroxide (TMTFTH) has gained widespread use for the derivatisation for GCMS analysis of organic materials found in artists' materials, such as oils, plant resins and waxes. This paper discusses products formed from reactions of TMTFTH with alcohols--including fatty alcohols, hydroxyacids, terpenes and glycerol--that have diagnostic value in the analysis of samples from artworks. In addition to methyl ethers, (trifluoromethyl)phenyl ethers were formed to variable degrees from the different types of alcohol. The products were identified from their EI mass spectra. An understanding of these multiple reaction products is important for the interpretation of GCMS data from complex samples, especially in the case of polyfunctional alcohols such as glycerol, which forms a number of methyl, (trifluoromethyl)phenyl and mixed ethers. The significance of the reaction products, and the relative advantages of TMTFTH as compared to alternative ammonium and sulfonium methylating reagents, are discussed. PMID:17188693

Sutherland, Ken

2006-12-26

292

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

Microsoft Academic Search

This paper describes the optimisation of headspace solid-phase microextraction (HS-SPME) conditions for the analysis of volatile compounds in oak chips used to accelerate wine aging as an alternative to traditional aging in oak barrels. The direct extraction of ground wood samples and the extraction of sample aqueous slurries using a divinylbenzene-carboxen-polydimethylsiloxane (DVB-CAR-PDMS) fibre were studied and compared. Optimal conditions for

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

2007-01-01

293

Analysis of non-esterified fatty acids in human samples by solid-phase-extraction and gas chromatography/mass spectrometry.  

PubMed

The determination of the fatty acid (FA) profile of lipid classes is essential for lipidomic analysis. We recently developed a GC/MS-method for the analysis of the FA profile of total FAs, i.e. the totality of bound and unbound FAs, in any given biological sample (TOFAs). Here, we present a method for the analysis of non-esterified fatty acids (NEFAs) in biological samples, i.e. the fraction that is present as extractable free fatty acids. Lipid extraction is performed according to Dole using 80/20 2-propanol/n-hexane (v/v), with 0.1% H2SO4. The fatty acid-species composition of this NEFA-fraction is determined as FAME after derivatization with our GC/MS-method on a BPX column (Shimadzu). Validation of the NEFA-method presented was performed in human plasma samples. The validated method has been used with human plasma, cells and tissues, as well as mammalian body fluids and tissue samples. The newly developed solid-phase-extraction (SPE)-GC-MS method allows the rapid separation of the NEFA-fraction from a neutral lipid extract of plasma samples. As a major advantage compared to G-FID-methods, GC-MS allows the use of stable isotope labeled fatty acid precursors to monitor fatty acid metabolism. PMID:24036177

Kopf, Thomas; Schmitz, Gerd

2013-08-16

294

Increasing productivity for the analysis of trace contaminants in food by gas chromatography-mass spectrometry using automated liner exchange, backflushing and heart-cutting.  

PubMed

Laboratories focusing on residue analysis in food are continuously seeking to increase sample throughput by minimizing sample preparation. Generic sample extraction methods such as QuEChERS lack selectivity and consequently extracts are not free from non-volatile material that contaminates the analytical system. Co-extracted matrix constituents interfere with target analytes, even if highly sensitive and selective GC-MS/MS is used. A number of GC approaches are described that can be used to increase laboratory productivity. These techniques include automated inlet liner exchange and column backflushing for preservation of the performance of the analytical system and heart-cutting two-dimensional GC for increasing sensitivity and selectivity. The application of these tools is illustrated by the analysis of pesticides in vegetables and fruits, PCBs in milk powder and coplanar PCBs in fish. It is demonstrated that considerable increase in productivity can be achieved by decreasing instrument down-time, while analytical performance is equal or better compared to conventional trace contaminant analysis. PMID:23891373

David, Frank; Tienpont, Bart; Devos, Christophe; Lerch, Oliver; Sandra, Pat

2013-07-12

295

Solventless sample preparation for pesticides analysis in environmental water samples using solid-phase microextraction-high resolution gas chromatography/mass spectrometry (SPME-HRGC/MS).  

PubMed

Solid-phase micro-extraction (SPME) coupled on line with high resolution gas chromatography and mass spectrometric detection is described for the analysis of pesticides in environmental water samples. Experiments were performed in order to optimize the SPME extraction conditions for selected pesticides including tiomethon, trichorfon, dimethoate, diazinon, malathion, dicofol, methidathion, ethion, bromopropylate and pyrazophos from spiked water solutions. To enhance the SPME efficiency, experimental conditions including the fiber composition, stirring rate, temperature, adsorption time, desorption time and salt concentration were optimized. After validation, the SPME-GC/MS methodology was applied to real-world environmental water samples. PMID:12856924

Souza, Dalva A; Lanças, Fernando M

2003-07-01

296

Methods of analysis by the U.S. Geological Survey Organic Geochemistry Research Group : determination of selected herbicides and their degradation products in water using solid-phase extraction and gas chromatography/mass spectrometry  

USGS Publications Warehouse

A method for the extraction and analysis of eight herbicides and five degradation products using solid-phase extraction from natural water samples followed by gas chromatography/mass spectrometry is presented in this report. This method was developed for dimethenamid; flufenacet; fluometuron and its degradation products, demethylfluometuron (DMFM), 3-(trifluromethyl)phenylurea (TFMPU), 3-(trifluromethyl)-aniline (TFMA); molinate; norflurazon and its degradation product, demethylnorflurazon; pendamethalin; the degradation product of prometryn, deisopropylprometryn; propanil; and trifluralin. The eight herbicides are used primarily in the southern United States where cotton, rice, and soybeans are produced. The exceptions are dimethenamid and flufenacet, which are used on corn in the Midwest. Water samples received by the U.S. Geological Survey's Organic Geochemistry Research Group in Lawrence, Kansas, are filtered to remove suspended particulate matter and then passed through disposable solid-phase extraction columns containing octadecyl-bonded porous silica (C-18) to extract the compounds. The herbicides and their degradation products are removed from the column by ethyl acetate elution. The eluate is evaporated under nitrogen, and components then are separated, identified, and quantified by injecting an aliquot of the concentrated extract into a high-resolution, fused-silica capillary column of a gas chromatograph/mass spectrometer under selected-ion mode. Method detection limits ranged from 0.02 to 0.05 ?g/L for all compounds with the exception of TFMPU, which has a method detection limit of 0.32 ?g/L. The mean absolute recovery is 107 percent. This method for the determination of herbicides and their degradation products is valuable for acquiring information about water quality and compound fate and transport in water.

Kish, J. L.; Thurman, E. M.; Scribner, E. A.; Zimmerman, L. R.

2000-01-01

297

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

USGS Publications Warehouse

A method for the isolation and analysis of 21 parent pesticides and 20 pesticide degradates in natural-water samples is described. Water samples are filtered to remove suspended particulate matter and then are pumped through disposable solid-phase-extraction columns that contain octadecyl-bonded porous silica to extract the analytes. The columns are dried by using nitrogen gas, and adsorbed analytes are eluted with ethyl acetate. Extracted analytes are determined by capillary-column gas chromatography/mass spectrometry with selected-ion monitoring of three characteristic ions. The upper concentration limit is 2 micrograms per liter (?g/L) for most analytes. Single-operator method detection limits in reagent-water samples range from 0.00 1 to 0.057 ?g/L. Validation data also are presented for 14 parent pesticides and 20 degradates that were determined to have greater bias or variability, or shorter holding times than the other compounds. The estimated maximum holding time for analytes in pesticide-grade water before extraction was 4 days. The estimated maximum holding time for analytes after extraction on the dry solid-phase-extraction columns was 7 days. An optional on-site extraction procedure allows for samples to be collected and processed at remote sites where it is difficult to ship samples to the laboratory within the recommended pre-extraction holding time. The method complements existing U.S. Geological Survey Method O-1126-95 (NWQL Schedules 2001 and 2010) by using identical sample preparation and comparable instrument analytical conditions so that sample extracts can be analyzed by either method to expand the range of analytes determined from one water sample.

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

2001-01-01

298

Methods of Analysis by the U.S. Geological Survey Organic Geochemistry Research Group-Update and Additions to the Determination of Chloroacetanilide Herbicide Degradation Compounds in Water Using High-Performance Liquid Chromatography/Mass Spectrometry  

USGS Publications Warehouse

An analytical method using high-performance liquid chromatography/mass spectrometry (HPLC/MS) was developed by the U.S. Geological Survey in 1999 for the analysis of selected chloroacetanilide herbicide degradation compounds in water. These compounds were acetochlor ethane sulfonic acid (ESA), acetochlor oxanilic acid (OXA), alachlor ESA, alachlor OXA, metolachlor ESA, and metolachlor OXA. The HPLC/MS method was updated in 2000, and the method detection limits were modified accordingly. Four other degradation compounds also were added to the list of compounds that can be analyzed using HPLC/MS; these compounds were dimethenamid ESA, dimethenamid OXA, flufenacet ESA, and flufenacet OXA. Except for flufenacet OXA, good precision and accuracy were demonstrated for the updated HPLC/MS method in buffered reagent water, surface water, and ground water. The mean HPLC/MS recoveries of the degradation compounds from water samples spiked at 0.20 and 1.0 ?g/L (microgram per liter) ranged from 75 to 114 percent, with relative standard deviations of 15.8 percent or less for all compounds except flufenacet OXA, which had relative standard deviations ranging from 11.3 to 48.9 percent. Method detection levels (MDL's) using the updated HPLC/MS method varied from 0.009 to 0.045 ?g/L, with the flufenacet OXA MDL at 0.072 ?g/L. The updated HPLC/MS method is valuable for acquiring information about the fate and transport of the parent chloroacetanilide herbicides in water.

Lee, E. A.; Kish, J. L.; Zimmerman, L. R.; Thurman, E.

2001-01-01

299

Screening of antioxidant phenolic compounds in Chinese rhubarb combining fast counter-current chromatography fractionation and liquid chromatography/mass spectrometry analysis.  

PubMed

In this paper, an effective method combing fast elution-extrusion counter-current chromatography (CCC) and LC/MS for rapid screening of antioxidative phenolic compounds in Chinese Rhubarb is presented. An integrated three-coil CCC column (40 mL each coil) was used to accomplish the optimization of biphasic liquid system. In a single run (approximately 40 min), the solvent system composed of n-hexane/ethyl acetate/methanol/water (1:1:1:1, v/v) was selected as optimum CCC liquid system for fast fractionation of the crude ethanol extract. With a 140 mL-capacity CCC instrument, 100 mg Chinese Rhubarb extract was separated under the optimized conditions, producing six fractions in only 100 min. The quantities of each fraction were approximately 15 mg. In addition, each fraction was subjected to antioxidant activity assay and characterized by LC/MS analysis. Fifty compounds, including phenolic acids, phenolic glucosides and hydroxyanthraquinones, were detected by LC/MS/MS analysis. As a result, gallic acid together with Fr I showed excellent antioxidant activity, which was well consistent with previous studies and exhibited great potential for natural drug discovery program of the present method. PMID:20405489

Hu, Ruilin; Lu, Yanbin; Dai, Xiaojing; Pan, Yuanjiang

2010-06-01

300

Analysis of sterols and fatty acids in natural and cultured Cordyceps by one-step derivatization followed with gas chromatography-mass spectrometry.  

PubMed

Ten free fatty acids namely lauric acid, myristic acid, pentadecanoic acid, palmitoleic acid, palmitic acid, linoleic acid, oleic acid, stearic acid, docosanoic acid and lignoceric acid and four free sterols including ergosterol, cholesterol, campesterol and beta-sitosterol in natural (wild) Cordyceps sinensis, Cordyceps liangshanensis and Cordyceps gunnii, as well as cultured C. sinensis and Cordyceps militaris were first determined using pressurized liquid extraction (PLE), trimethylsilyl (TMS) derivatization and GC-MS analysis. The conditions such as the amount of reagent, temperature and time for TMS derivatization of analytes were optimized. Under the optimum conditions, all calibration curves showed good linearity within the tested ranges. The intra- and inter-day variations for 14 investigated compounds were less than 3.4% and 5.2%, respectively. The results showed that palmitic acid, linoleic acid, oleic acid, stearic acid and ergosterol are main components in natural and cultured Cordyceps which could be discriminated by hierarchical clustering analysis based on the contents of 14 investigated compounds or the 4 fatty acids, where the contents of palmitic acid and oleic acid in natural Cordyceps are significantly higher than those in the cultured ones. PMID:19339130

Yang, F Q; Feng, K; Zhao, J; Li, S P

2009-03-09

301

Comparison of sample preparation methods combined with fast gas chromatography-mass spectrometry for ultratrace analysis of pesticide residues in baby food.  

PubMed

Four sample preparation techniques were compared for the ultratrace analysis of pesticide residues in baby food: (a) modified Schenck's method based on ACN extraction with SPE cleaning; (b) quick, easy, cheap, effective, rugged, and safe (QuEChERS) method based on ACN extraction and dispersive SPE; (c) modified QuEChERS method which utilizes column-based SPE instead of dispersive SPE; and (d) matrix solid phase dispersion (MSPD). The methods were combined with fast gas chromatographic-mass spectrometric analysis. The effectiveness of clean-up of the final extract was determined by comparison of the chromatograms obtained. Time consumption, laboriousness, demands on glassware and working place, and consumption of chemicals, especially solvents, increase in the following order QuEChERS < modified QuEChERS < MSPD < modified Schenck's method. All methods offer satisfactory analytical characteristics at the concentration levels of 5, 10, and 100 microg/kg in terms of recoveries and repeatability. Recoveries obtained for the modified QuEChERS method were lower than for the original QuEChERS. In general the best LOQs were obtained for the modified Schenck's method. Modified QuEChERS method provides 21-72% better LOQs than the original method. PMID:16830724

Hercegová, Andrea; Dömötörová, Milena; Kruzlicová, Dása; Matisová, Eva

2006-05-01

302

Multiresidue analysis of plant growth regulators in grapes by triple quadrupole and quadrupole-time of flight-based liquid chromatography/mass spectrometry.  

PubMed

A selective and sensitive LC-MS/MS method is presented for simultaneous determination of 12 plant growth regulators, viz., indol-3-acetic acid, indol-3-butyric acid, kinetin, zeatin, 6-benzyl aminopurine, gibberellic acid, abscisic acid, chlormequat chloride, forchlorfenuron, paclobutrazole, daminozide, and 2,4-dichlorophenoxy acetic acid, in bud sprouts and grape berries. The sample preparation method involved extraction of homogenized sample (5 g) with 40 mL methanol (80%), and final determination was by LC-MS/MS in the multiple reaction monitoring (MRM) mode with time segmentation for quantification supported by complementary analysis by quadrupole-time of flight (Q-TOF) MS with targeted high-resolution MS/MS scanning for confirmatory identification based on accurate mass measurements. The recovery of the test compounds ranged within 90-107% with precision RSD less than 5% (n = 6). The method could be successfully applied in analyzing incurred residue samples, and the strength of accurate mass analysis could be utilized in identifying the compounds in cases where the qualifier MRM ions were absent or at an S/N less than 3:1 due to low concentrations. PMID:22320078

Oulkar, Dasharath P; Banerjee, Kaushik; Kulkarni, Sunil

303

Simultaneous determination of beta-blocking agents and diuretics in doping analysis by liquid chromatography/mass spectrometry with scan-to-scan polarity switching.  

PubMed

A previously described method for the screening of 18 diuretics and probenecid was substantially extended with 21 beta-blockers and 8 other diuretics allowing simultaneous determination of diuretics and beta-adrenergic blocking agents in human urine. Analysis was performed using an ion trap instrument with an electrospray ionisation (ESI) interface after liquid/liquid extraction with ethyl acetate. Full-scan MS and full-scan MS2 were applied in combination with scan-to-scan polarity switching. All compounds were separated in less than 22 min. The detection limits for the diuretics were between 5 and 100 ng/mL and for the beta-adrenergic blocking agents were between 5 and 500 ng/mL. The excretion of carvedilol was followed after intake of one tablet of Dimitone. Other doping agents including strychnine, norbuprenorphine and mesocarb hydroxysulfate could also be detected with this method. PMID:15584083

Deventer, K; Van Eenoo, P; Delbeke, F T

2005-01-01

304

Preparation of phenyl group-functionalized magnetic mesoporous silica microspheres for fast extraction and analysis of acetaldehyde in mainstream cigarette smoke by gas chromatography-mass spectrometry.  

PubMed

Acetaldehyde is regarded as a toxic mainstream cigarette smoke constituent, and measurement of acetaldehyde in complex real samples is difficult owing to its high volatility and reactivity. In this work, phenyl group-functionalized magnetic mesoporous microspheres were developed as the solid-phase extraction sorbents for enrichment and analysis of acetaldehyde in mainstream cigarette smoke. The functional magnetic microspheres were first synthesized through a facile one-pot co-condensation approach. The prepared nanomaterials possessed abundant silanol groups in the exterior surface and numerous phenyl groups in the interior pore-walls, as well as a large surface area (273.5m(2)/g), strong superparamagnetism and uniform mesopores (3.3nm). Acetaldehyde in mainstream cigarette smoke was collected in water and derivatizated with O-2,3,4,5,6-(pentafluorobenzyl)hydroxylamine. The formed acetaldehyde oximes were extracted and enriched by the prepared adsorbents via ?-? interactions and subsequently analyzed using GC-MS. Extraction conditions such as amounts of sorbents, eluting solvent, adsorption and desorption time were investigated and optimized to achieve the best efficiency. Method validations including linearity, recovery, repeatability, and limit of detection were also studied. It was found that the suggested methodology provided low detection limit of 0.04mg/mL, good recovery of 88-92%, intra-day and inter-day RSD values of 4.5% and 10.1%, and linear range of 0.25-4mg/mL (R(2)=0.999). The results indicated that the proposed method based on phenyl-functionalized magnetic mesoporous microspheres was rapid, efficient and convenient for the enrichment and analysis of acetaldehyde in tobacco. PMID:24054614

Huang, Danni; Sha, Yunfei; Zheng, Saijing; Liu, Baizhan; Deng, Chunhui

2013-06-06

305

Analysis of human skin emanations by gas chromatography/mass spectrometry. 1. Thermal desorption of attractants for the yellow fever mosquito (Aedes aegypti) from handled glass beads.  

PubMed

Handled glass has the ability to collect and concentrate nonaqueous human skin emanations while minimizing the collection of aqueous perspiration. Compounds originating from the skin and collected on glass have previously been found to attract the Aedes aegypti species of mosquito. Therefore, glass beads were used as the medium to collect skin emanations from humans for subsequent chemical analysis. This process consisted of a 5-15-min collection of sample on glass beads, followed by loading the beads into a gas chromatograph (GC) injector insert for subsequent desorption of the collected compounds onto the GC column. After cryofocusing by liquid nitrogen at the head of the column, the thermally desorbed compounds were analyzed by GC/MS. Microscale purge and trap introduction was also used to provide complementary information. In this case, the beads are held in a round-bottom flask, purged with nitrogen, and heated as the concentrator collects the headspace above the beads. The chromatograms produced by both of these sample introduction methods demonstrate good resolution of a complex sample. Cryofocusing volatiles from handled glass allowed identification of lactic acid, aliphatic fatty acids, and other polar to nonpolar compounds of moderate volatility while purge and trap allowed detection of nonpolar to moderately polar compounds of high volatility. PMID:9921122

Bernier, U R; Booth, M M; Yost, R A

1999-01-01

306

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

PubMed

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

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

2012-05-12

307

Analysis of free and protein-bound nitrotyrosine in human plasma by a gas chromatography/mass spectrometry method that avoids nitration artifacts.  

PubMed Central

Measurement of nitrotyrosine in biological fluids and tissues is increasingly being used to monitor the production of reactive nitrogen species in vivo. The detection of nitrotyrosine in vivo has been reported with the use of a variety of methods including immunoassay, HPLC and GLC/MS. The validity of HPLC and immunoassays have been questioned with regard to their selectivity and sensitivity limits. In principle, the measurement of nitrotyrosine by GLC/MS permits a highly specific, highly sensitive and fully quantitative assay. The nitration of tyrosine under acidic conditions in the presence of nitrite is well documented. Derivatization for the full quantification of nitrotyrosine by using GLC/MS can lead to the artifactual nitration of tyrosine if performed under acidic conditions in the presence of nitrite. We describe a novel alkaline method for the hydrolysis and derivatization of nitrotyrosine and tyrosine, and demonstrate its applicability to the measurement of plasma concentrations of both free and protein-bound nitrotyrosine and tyrosine. A detection limit of 1 pg for nitrotyrosine and 100 pg for tyrosine has been achieved. Our method allows, for the first time, the analysis of free and protein-bound nitrotyrosine and tyrosine in biological samples. The plasma concentrations (means+/-S.E.M.) of free tyrosine and nitrotyrosine in eight normal subjects were 12+/-0.6 microg/ml and 14+/-0.7 ng/ml respectively. Plasma proteins contained tyrosine and nitrotyrosine at 60.7+/-1.7 microg/mg and 2.7+/-0.4 ng/mg respectively.

Frost, M T; Halliwell, B; Moore, K P

2000-01-01

308

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

PubMed

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

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

2008-07-01

309

Rapid and sensitive liquid chromatography/mass spectrometry assay for caspofungin in human aqueous humor.  

PubMed

A rapid, precise, and sensitive liquid chromatography/mass spectrometry (LC/MS) method to quantify the caspofungin concentration in human aqueous humor was developed and validated. Sample preparation involved simple dilution of aqueous humor samples with acetonitrile. Azithromycin was the internal standard. Good linearity over 10 to 5,000 ng/ml was observed. The lower limit of quantification was 10 ng/ml. The intra- and interday accuracies (percent bias) were within 11%, while the intra- and interday precisions were within 6%. PMID:20660672

Neoh, Chin Fen; He, Hui; Li, Jian; Fullinfaw, Robert O; Leung, Lok; Misra, Anant; Vajpayee, Rasik B; Davies, Geoffrey E; Stewart, Kay; Kong, David C M

2010-07-26

310

Rapid and Sensitive Liquid Chromatography/Mass Spectrometry Assay for Caspofungin in Human Aqueous Humor ?  

PubMed Central

A rapid, precise, and sensitive liquid chromatography/mass spectrometry (LC/MS) method to quantify the caspofungin concentration in human aqueous humor was developed and validated. Sample preparation involved simple dilution of aqueous humor samples with acetonitrile. Azithromycin was the internal standard. Good linearity over 10 to 5,000 ng/ml was observed. The lower limit of quantification was 10 ng/ml. The intra- and interday accuracies (percent bias) were within 11%, while the intra- and interday precisions were within 6%.

Neoh, Chin Fen; He, Hui; Li, Jian; Fullinfaw, Robert O.; Leung, Lok; Misra, Anant; Vajpayee, Rasik B.; Davies, Geoffrey E.; Stewart, Kay; Kong, David C. M.

2010-01-01

311

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

Microsoft Academic Search

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

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

1999-01-01

312

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

313

Liquid-chromatography mass spectrometry (LC-MS) of steroid hormone metabolites and its applications  

PubMed Central

Advances in liquid chromatography-mass spectrometry (LC-MS) can be used to measure steroid hormone metabolites in vitro and in vivo. We find that LC-Electrospray Ionization (ESI)-MS using a LCQ ion trap mass spectrometer in the negative ion mode can be used to monitor the product profile that results from 5?–dihydrotestosterone(DHT)-17?-glucuronide, DHT-17?-sulfate, and tibolone-17?-sulfate reduction catalyzed by human members of the aldo-keto reductase (AKR) 1C subfamily and assign kinetic constants to these reactions. We also developed a stable-isotope dilution LC-electron capture atmospheric pressure chemical ionization (ECAPCI)-MS method for the quantitative analysis of estrone (E1) and its metabolites as pentafluorobenzyl (PFB) derivatives in human plasma in the attomole range. The limit of detection for E1-PFB was 740 attomole on column. Separations can be performed using normal-phase LC because ionization takes place in the gas phase rather than in solution. This permits efficient separation of the regioisomeric 2- and 4-methoxy-E1. The method was validated for the simultaneous analysis of plasma E2 and its metabolites: 2-methoxy-E2, 4-methoxy-E2, 16?-hydroxy-E2, estrone (E1), 2-methoxy-E1, 4-methoxy-EI, and 16?-hydroxy-E1 from 5 pg/mL to 2,000 pg/mL. Our LC-MS methods have sufficient sensitivity to detect steroid hormone levels in prostate and breast tumors and should aid their molecular diagnosis and treatment.

Penning, Trevor M.; Lee, Seon-Hwa; Jin, Yi; Gutierrez, Alejandro; Blair, Ian A.

2010-01-01

314

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

Microsoft Academic Search

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

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

2005-01-01

315

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

PubMed

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

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

2010-02-12

316

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

PubMed

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

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

2013-04-29

317

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

PubMed

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

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

2006-06-30

318

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

PubMed

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

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

2012-03-01

319

A new approach to untargeted integration of high resolution liquid chromatography-mass spectrometry data.  

PubMed

Because of its high sensitivity and specificity, hyphenated mass spectrometry has become the predominant method to detect and quantify metabolites present in bio-samples relevant for all sorts of life science studies being executed. In contrast to targeted methods that are dedicated to specific features, global profiling acquisition methods allow new unspecific metabolites to be analyzed. The challenge with these so-called untargeted methods is the proper and automated extraction and integration of features that could be of relevance. We propose a new algorithm that enables untargeted integration of samples that are measured with high resolution liquid chromatography-mass spectrometry (LC-MS). In contrast to other approaches limited user interaction is needed allowing also less experienced users to integrate their data. The large amount of single features that are found within a sample is combined to a smaller list of, compound-related, grouped feature-sets representative for that sample. These feature-sets allow for easier interpretation and identification and as important, easier matching over samples. We show that the automatic obtained integration results for a set of known target metabolites match those generated with vendor software but that at least 10 times more feature-sets are extracted as well. We demonstrate our approach using high resolution LC-MS data acquired for 128 samples on a lipidomics platform. The data was also processed in a targeted manner (with a combination of automatic and manual integration) using vendor software for a set of 174 targets. As our untargeted extraction procedure is run per sample and per mass trace the implementation of it is scalable. Because of the generic approach, we envision that this data extraction lipids method will be used in a targeted as well as untargeted analysis of many different kinds of TOF-MS data, even CE- and GC-MS data or MRM. The Matlab package is available for download on request and efforts are directed toward a user-friendly Windows executable. PMID:24139572

van der Kloet, Frans M; Hendriks, Margriet; Hankemeier, Thomas; Reijmers, Theo

2013-09-23

320

Precision and Accuracy in the Determination of Organics in Water by Fused Silica Capillary Column Gas Chromotography/Mass Spectrometry and Packed Column Gas Chromatography/Mass Spectrometry.  

National Technical Information Service (NTIS)

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

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

1983-01-01

321

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

PubMed

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

Bir, David; Tutin, Kim

2002-07-01

322

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

PubMed

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

Chu, Mark Hok Chi; Drummer, Olaf H

323

Principles and Applications of Liquid Chromatography-Mass Spectrometry in Clinical Biochemistry  

PubMed Central

Liquid chromatography-mass spectrometry (LC-MS) is now a routine technique with the development of electrospray ionisation (ESI) providing a simple and robust interface. It can be applied to a wide range of biological molecules and the use of tandem MS and stable isotope internal standards allows highly sensitive and accurate assays to be developed although some method optimisation is required to minimise ion suppression effects. Fast scanning speeds allow a high degree of multiplexing and many compounds can be measured in a single analytical run. With the development of more affordable and reliable instruments, LC-MS is starting to play an important role in several areas of clinical biochemistry and compete with conventional liquid chromatography and other techniques such as immunoassay.

Pitt, James J

2009-01-01

324

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

NASA Astrophysics Data System (ADS)

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

Little, James L.; Howard, Adam S.

2013-10-01

325

Trace detection of meglumine and diatrizoate from Bacillus spore samples using liquid chromatography/mass spectrometry.  

PubMed

Following the September 11, 2001 terrorist attacks, letters containing Bacillus anthracis were distributed through the United States postal system killing five people. A complex forensic investigation commenced to identify the perpetrator of these mailings. A novel liquid chromatography/mass spectrometry protocol for the qualitative detection of trace levels of meglumine and diatrizoate in dried spore preparations of B. anthracis was developed. Meglumine and diatrizoate are components of radiographic imaging products that have been used to purify bacterial spores. Two separate chromatographic assays using multiple mass spectrometric analyses were developed for the detection of meglumine and diatrizoate. The assays achieved limits of detection for meglumine and diatrizoate of 1.00 and 10.0 ng/mL, respectively. Bacillus cereus T strain spores were effectively used as a surrogate for B. anthracis spores during method development and validation. This protocol was successfully applied to limited evidentiary B. anthracis spore material, providing probative information to the investigators. PMID:22537353

Swider, Catherine; Maguire, Kelly; Rickenbach, Michael; Montgomery, Madeline; Ducote, Matthew J; Marhefka, Craig A

2012-04-26

326

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

SciTech Connect

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

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

1981-01-01

327

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

PubMed

Basil plants cultivated by organic and conventional farming practices were accurately classified by pattern recognition of gas chromatography/mass spectrometry (GC/MS) data. A novel extraction procedure was devised to extract characteristic compounds from ground basil powders. Two in-house fuzzy classifiers, i.e., the fuzzy rule-building expert system (FuRES) and the fuzzy optimal associative memory (FOAM) for the first time, were used to build classification models. Two crisp classifiers, i.e., soft independent modeling by class analogy (SIMCA) and the partial least-squares discriminant analysis (PLS-DA), were used as control methods. Prior to data processing, baseline correction and retention time alignment were performed. Classifiers were built with the two-way data sets, the total ion chromatogram representation of data sets, and the total mass spectrum representation of data sets, separately. Bootstrapped Latin partition (BLP) was used as an unbiased evaluation of the classifiers. By using two-way data sets, average classification rates with FuRES, FOAM, SIMCA, and PLS-DA were 100 ± 0%, 94.4 ± 0.4%, 93.3 ± 0.4%, and 100 ± 0%, respectively, for 100 independent evaluations. The established classifiers were used to classify a new validation set collected 2.5 months later with no parametric changes except that the training set and validation set were individually mean-centered. For the new two-way validation set, classification rates with FuRES, FOAM, SIMCA, and PLS-DA were 100%, 93%, 97%, and 100%, respectively. Thereby, the GC/MS analysis was demonstrated as a viable approach for organic basil authentication. It is the first time that a FOAM has been applied to classification. A novel baseline correction method was used also for the first time. The FuRES and the FOAM are demonstrated as powerful tools for modeling and classifying GC/MS data of complex samples, and the data pretreatments are demonstrated to be useful to improve the performance of classifiers. PMID:23398171

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

2013-02-22

328

Performance Evaluation of three Liquid Chromatography Mass Spectrometry Methods for Broad Spectrum Drug Screening  

PubMed Central

BACKGROUND Liquid chromatography-mass spectrometry (LC-MS) and tandem LC-MS (LC-MS/MS) are increasingly used in toxicology laboratories as a complementary method to gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-ultraviolet detection (LC-UV) for comprehensive drug screening (CDS). This study was designed to characterize the sensitivity and specificity of three LC-MS(/MS) vendor-supplied methods for targeted CDS and identify the current limitations associated with the use of these technologies. METHODS Five methods for broad spectrum CDS, including LC-UV (REMEDi), full scan GC-MS, LC-MS (ZQ™-Mass Detector with MassLynx™-software), LC-QTRAP-MS/MS (3200-QTRAP® with Cliquid®-software) and LC-LIT-MS/MS (LXQ™ Linear Ion Trap with ToxID™-software) were evaluated based on their ability to detect drugs in 48 patient urine samples. RESULTS The tandem MS methods identified 15% more drugs than the single stage MS or LC-UV methods. Use of two broad spectrum screening methods identified more drugs than any single system alone. False negatives and false positives generated by the LC-MS(/MS) software programs were identified upon manual review of the raw data. CONCLUSIONS The LC-MS/MS methods detected a broader menu of drugs; however, it is essential to establish manual data review criteria for all LC-MS(/MS) drug screening methods. Use of an EI-GC-MS and ESI-LC-MS/MS combination for targeted CDS may be optimal due to the complementary nature of the chromatographic and ionization techniques.

Lynch, Kara L.; Breaud, Autumn R.; Vandenberghe, Hilde; Wu, Alan H. B.; Clarke, William

2010-01-01

329

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

PubMed

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

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

330

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

Microsoft Academic Search

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

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

2003-01-01

331

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

Microsoft Academic Search

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

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

1999-01-01

332

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

Microsoft Academic Search

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

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

2003-01-01

333

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

PubMed

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

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

2013-06-03

334

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

PubMed Central

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

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

1990-01-01

335

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

PubMed

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

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

1990-05-01

336

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

PubMed

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

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

1998-12-01

337

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

PubMed

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

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

2013-08-21

338

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

PubMed

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

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

2001-06-01

339

Column liquid chromatography-mass spectrometry: Selected techniques in environmental applications for polar pesticides and related compounds  

Microsoft Academic Search

A review covering the field of environmental applications of liquid chromatography-mass spectrometry (LC-MS) is presented. Recent developments and advances are discussed with emphasis on the presently popular thermospray, particle beam and atmospheric pressure ionisation interfaces. Each interface is described separately covering the principle of operation, typical detection limits and characteristics of the mass spectra. All reviewed interfacing techniques provide useful

J. Slobodnik; B. L. M van Baar; U. A. Th Brinkman

1995-01-01

340

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

Microsoft Academic Search

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

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

341

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

EPA Science Inventory

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

342

Toxin profile of Alexandrium ostenfeldii (Dinophyceae) from the Northern Adriatic Sea revealed by liquid chromatography–mass spectrometry  

Microsoft Academic Search

This paper reports on the first occurrence of fairly high numbers of Alexandrium ostenfeldii along the Emilia Romagna coasts (Italy). Detailed liquid chromatography–mass spectrometry (LC–MS) analyses of the toxin profile were performed on a strain of the organism collected in November 2003, isolated during the event and grown in culture. Selected ion monitoring (SIM) and multiple reaction monitoring (MRM) experiments

Patrizia Ciminiello; Carmela Dell'Aversano; Ernesto Fattorusso; Silvana Magno; Luciana Tartaglione; Monica Cangini; Marinella Pompei; Franca Guerrini; Laurita Boni; Rossella Pistocchi

2006-01-01

343

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

Microsoft Academic Search

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

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

2007-01-01

344

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

Microsoft Academic Search

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

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

2005-01-01

345

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

Microsoft Academic Search

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

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

2000-01-01

346

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

Microsoft Academic Search

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

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

1988-01-01

347

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

Microsoft Academic Search

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

Shin-Fang Wu; Wang-Hsien Ding

2010-01-01

348

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

349

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

350

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

Microsoft Academic Search

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

Frank Sporkert; Fritz Pragst

2000-01-01

351

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

Microsoft Academic Search

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

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

2009-01-01

352

New approach to the direct detection of known and new diarrhoeic shellfish toxins in mussels and phytoplankton by liquid chromatography–mass spectrometry  

Microsoft Academic Search

A new approach using combined liquid chromatography–mass spectrometry (LC–MS) with ionspray ionization is proposed for the direct detection of known and new toxins in mussels and phytoplankton. A first stage reversed-phase, negative ion mode, selected ion monitoring (SIM) LC–MS analysis was performed in order to detect DSP toxins in the same chromatographic run with a total run time of 20

R Draisci; L Palleschi; L Giannetti; L Lucentini; K. J James; A. G Bishop; M Satake; T Yasumoto

1999-01-01

353

Effect of Fructose and glucose on glycation of ?-lactoglobulin in an intermediate-moisture food model system: analysis by liquid chromatography-mass spectrometry (LC-MS) and data-independent acquisition LC-MS (LC-MS(E)).  

PubMed

To evaluate the effect of glucose and fructose on the glycation of ?-lactoglobulin (?-Lg) in intermediate-moisture food (IMF), model systems consisting of ?-Lg, glucose/fructose/sorbitol, glycerol, and water were established. All systems were stored at 25 and 35 °C for 2 months. The progress of the Maillard reaction and the mass change of ?-Lg were investigated by the browning assay and gel electrophoresis, respectively. Meanwhile, liquid chromatography-mass spectrometry (LC-MS) and data-independent acquisition LC-MS (LC-MS(E)) were used to monitor the glycation extent and the glycated sites of ?-Lg. The results indicated that glucose had a higher reaction activity of glycation than fructose, but both sugars had similar preference on the glycation site for ?-Lg. The ranking order from high to low for the 9 detected glycated sites was L 1, K 91 > K 47 > K 70, K 77, K 83, K 100 > K 75 > K 135 for both sugars. PMID:23020204

Chen, Ying-jia; Liang, Li; Liu, Xiao-ming; Labuza, Theodore P; Zhou, Peng

2012-10-11

354

Evaluation of analysis of polycyclic aromatic hydrocarbons by the QuEChERS method and gas chromatography-mass spectrometry and their formation in poultry meat as affected by marinating and frying.  

PubMed

The objectives of this research were to develop a method for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in poultry meat by combining the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method with gas chromatography-mass spectrometry (GC-MS) and study their formation during marinating and frying. The recoveries of 16 PAHs ranged from 94.5 to 104% in blank samples and from 71.2 to 104% in poultry meat samples. The quantitation limits of 16 PAHs were from 0.02 to 1 ng/mL, with the intraday variability being from 2.4 to 6.6% [percent relative standard deviation (RSD%)] and interday variability being from 3.3 to 7.1% (RSD%). Most PAHs followed a time-dependent increase over a 24 h marinating period, with naphthalene being generated in the largest amount. Among the various poultry meat, chicken gizzard produced the highest level of total PAHs after 24 h of marinating. A similar tendency was observed for most PAHs during frying of poultry meat, but a high amount of total PAHs was shown in duck drumstick after 15 min of frying. PMID:22233505

Kao, Tsai Hua; Chen, Shaun; Chen, Chia Ju; Huang, Chung Wei; Chen, Bing Huei

2012-01-31

355

Simultaneous analysis of oxygenated and nitrated polycyclic aromatic hydrocarbons on standard reference material 1649a (urban dust) and on natural ambient air samples by gas chromatography-mass spectrometry with negative ion chemical ionisation.  

PubMed

This study deals with the development of a routine analytical method using gas chromatography-mass spectrometry with negative ion chemical ionisation (GC/NICI-MS) for the determination of 17 nitrated polycyclic aromatic hydrocarbons (NPAHs) and 9 oxygenated polycyclic aromatic hydrocarbons (OPAHs) present at low concentrations in the atmosphere. This method includes a liquid chromatography purification procedure on solid-phase extraction (SPE) cartridge. Application of this analytical procedure has been performed on standard reference material (SRM 1649a: urban dust), giving results in good agreement with the few data available in the literature. The analytical method was also applied on ambient air samples (on both gas and particulate phases) from the French POVA program (POllution des Vallées Alpines). NPAHs concentrations observed for a rural site during the Winter period are about 0.2-100.0pgm(-3) in the particulate phase and about 0.0-20.0pgm(-3) in the gas phase. OPAHs present concentrations 10-100 times higher (0.1-2.0ngm(-3) and 0.0-1.4ngm(-3) for the particulate and the gas phases, respectively). These preliminary results show a good correlation between the characteristics of the sampling site and the compound origins (primary or secondary). PMID:16682050

Albinet, A; Leoz-Garziandia, E; Budzinski, H; Viilenave, E

2006-05-08

356

Analysis of enantiomeric and non-enantiomeric monoterpenes in plant emissions using portable dynamic air sampling/solid-phase microextraction (PDAS-SPME) and chiral gas chromatography/mass spectrometry  

NASA Astrophysics Data System (ADS)

A portable dynamic air sampler (PDAS) using a porous polymer solid-phase microextraction (SPME) fibre has been validated for the determination of biogenic enantiomeric and non-enantiomeric monoterpenes in air. These compounds were adsorbed in the field, and then thermally desorbed at 250 °C in a gas chromatograph injector port connected via a ?-cyclodextrin capillary separating column to a mass spectrometer. The optimized method has been applied for investigating the emissions of enantiomeric monoterpenes from Pseudotsuga menziesii (Douglas-fir), Rosmarinus officinalis (Rosemary) and Lavandula lanata (Lavender) which were selected as representative of coniferous trees and aromatic plants, respectively. The enantiomers of ?-pinene, sabinene, camphene, ?-3-carene, ?-pinene, limonene, ?-phellandrene, 4-carene and camphor were successfully determined in the emissions from the three plants. While Douglas-fir showed a strong predominance toward (-)-enantiomers, Rosemary and Lavender demonstrated a large variation in enantiomeric distribution of monoterpenes. The simplicity, rapidity and sensitivity of dynamic sampling with porous polymer coated SPME fibres coupled to chiral capillary gas chromatography/mass spectrometry (GC/MS) makes this method potentially useful for in-field investigations of atmosphere-biosphere interactions and studies of optically explicit atmospheric chemistry.

Yassaa, Noureddine; Williams, Jonathan

357

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

Microsoft Academic Search

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

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

2003-01-01

358

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

PubMed

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

Bügler, Jürgen; Buchner, Hans; Dallmayer, Anton

359

Analysis of phenolic compounds by high-performance liquid chromatography and liquid chromatography/mass spectrometry in potato plant flowers, leaves, stems, and tubers and in home-processed potatoes.  

PubMed

Potato plants synthesize phenolic compounds as protection against bruising and injury from bacteria, fungi, viruses, and insects. Because antioxidative phenolic compounds are also reported to participate in enzymatic browning reactions and to exhibit health-promoting effects in humans, a need exists for accurate methods to measure their content in fresh and processed potatoes. To contribute to our knowledge about the levels of phenolic compounds in potatoes, we validated and used high-performance liquid chromatography and liquid chromatography/mass spectrometry to measure levels of chlorogenic acid, a chlorogenic isomer, and caffeic acid in flowers, leaves, stems, and tubers of the potato plant and in home-processed potatoes. The total phenolic acid content of flowers (626 mg/100 g fresh wt) was 21 and 59 times greater than that of leaves and stems, respectively. For all samples, chlorogenic acid and its isomer contributed 96-98% to the total. Total phenolic acid levels (in g/100 g fresh wt) of peels of five potato varieties grown in Korea ranged from 6.5 to 42.1 and of the flesh (pulp) from 0.5 to 16.5, with peel/pulp ratios ranging from 2.6 to 21.1. The total phenolic acid content for 25 American potatoes ranged from 1.0 to 172. The highest amounts were present in red and purple potatoes. Home processing of pulp with various forms of heat induced reductions in the phenolic content. The described methodology should facilitate future studies on the role of potato phenolic compounds in the plant and the diet. PMID:18386928

Im, Hyon Woon; Suh, Bong-Soon; Lee, Seung-Un; Kozukue, Nobuyuki; Ohnisi-Kameyama, Mayumi; Levin, Carol E; Friedman, Mendel

2008-04-04

360

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

PubMed

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

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

2011-10-01

361

Liquid chromatography-mass spectrometry to study chondroitin lyase action pattern.  

PubMed

Liquid chromatography-mass spectrometry was applied to determine the action pattern of different chondroitin lyases. Two commercial enzymes, chondroitinase ABC (Proteus vulgaris) and chondroitinase ACII (Arthrobacter aurescens), having action patterns previously determined by viscosimetry and gel electrophoresis were first examined. Next, the action patterns of recombinant lyases, chondroitinase ABC from Bacteroides thetaiotaomicron (expressed in Escherichia coli) and chondroitinase AC from Flavobacterium heparinum (expressed in its original host), were examined. Chondroitin sulfate A (CS-A, also known as chondroitin-4-sulfate) was used as the substrate for these four lyases. Aliquots taken at various time points were analyzed. The products of chondroitinase ABC (P. vulgaris) and chondroitinase AC (F. heparinum) contained unsaturated oligosaccharides of sizes ranging from disaccharide to decasaccharide, demonstrating that both are endolytic enzymes. The products afforded by chondroitinase ABC (B. thetaiotaomicron) and chondroitinase ACII (A. aurescens) contained primarily unsaturated disaccharide. These two exolytic enzymes showed different minor products, suggesting some subtle specificity differences between the actions of these two exolytic lyases on chondroitin sulfate A. PMID:18992215

Zhang, Zhenqing; Park, Youmie; Kemp, Melissa M; Zhao, Wenjing; Im, A-Rang; Shaya, David; Cygler, Miroslaw; Kim, Yeong Shik; Linhardt, Robert J

2008-10-17

362

Small molecule quantification by liquid chromatography-mass spectrometry for metabolites of drugs and drug candidates.  

PubMed

Identification and quantification of the metabolites of drugs and drug candidates are routinely performed using liquid chromatography-mass spectrometry (LC-MS). The best practice is to generate a standard curve with the metabolite versus the internal standard. However, to avoid the difficulties in metabolite synthesis, standard curves are sometimes prepared using the substrate, assuming that the signal for substrate and the metabolite will be equivalent. We have tested the errors associated with this assumption using a series of very similar compounds that undergo common metabolic reactions using both conventional flow electrospray ionization LC-MS and low-flow captive spray ionization (CSI) LC-MS. The differences in standard curves for four different types of transformations (O-demethylation, N-demethylation, aromatic hydroxylation, and benzylic hydroxylation) are presented. The results demonstrate that the signals of the substrates compared with those of the metabolites are statistically different in 18 of the 20 substrate-metabolite combinations for both methods. The ratio of the slopes of the standard curves varied up to 4-fold but was slightly less for the CSI method. PMID:21937735

Dahal, Upendra P; Jones, Jeffrey P; Davis, John A; Rock, Dan A

2011-09-21

363

An optimized electrochemistry-liquid chromatography-mass spectrometry method for studying guanosine oxidation  

PubMed Central

Oxidative stress can disrupt the integrity of genetic material. Due to its importance in the pathogenesis of different kinds of disease, including neurodegenerative disease, cardiovascular disease and cancer, major efforts are put into the elucidation of mechanisms involved. Herein, the combination of electrochemistry/liquid chromatography/mass spectrometry (EC/LC/MS) is presented as convenient, fast and simple method to study nucleic acids oxidation. Guanosine was selected as test compound. 8-Hydroxyguanosine and (guanosine-H)2 were identified as primary oxidation products. Oxidation was accomplished in an electrochemical thin-layer cell integrated in the flow path of the autosampler of the chromatographic system. The reaction mixture was separated and mass analyzed by LC/MS. The use of LC was found to be particularly beneficial to resolve isobaric oxidation products. Another advantage of the setup used was the ability to decouple the electrochemical cell and the electrospray ionization source from each other eliminating any kind of cell potential interaction. Separation of EC from LC/MS, furthermore, facilitates method optimization. Experimental parameters were optimized for both techniques independently. Highest yields and best detectability of oxidation products were obtained with 10 mM ammonium formate at physiological pH delivered at a flow rate of 2.5-5 ?L/min through the electrochemical cell.

Erb, Robert; Plattner, Sabine; Pitterl, Florian; Brouwer, Hendrik-Jan; Oberacher, Herbert

2012-01-01

364

Performance of an improved monodisperse aerosol generation interface for liquid chromatography/mass spectrometry  

SciTech Connect

An improved monodisperse aerosol generation interface for liquid chromatography/mass spectrometry interfacing (MAG-IC-LC/MS) is described. The interface has an aerodynamically superior momentum separator, which results in decreased analyte loss in passing through the interface. The interface is shown to perform well with a quadrupole mass spectrometer, in addition to earlier studies with a magnetic sector instrument. A new method of forming aerosol has been developed, which reduces the dead volume significantly over earlier designs. The performance of the interface has been evaluated by studying its capabilities for (1) generating electron impact spectra of searchable quality for selected compounds of interest, (2) operating with typical liquid chromatographic separation conditions, including reverse phase and gradient elution, and (3) providing low detection limits for both full scan and selective ion monitoring detection of a range of compounds. Studies include identification of the components of a mixture of cis and trans isomers of the thermally labile compound retinol (vitamin A) acetate. Full scan (m/z 80-350) electron impact spectra were readily obtained with 50-ng injection on-column. Detection limits for this compound were 10 ng full scan and 1 ng with selected ion monitoring. Identification of a free (nonderivatized) fatty acid mixture was also readily obtained, using a reversed-phase separation in gradient mode.

Winkler, P.C.; Perkins, D.D.; Williams, W.K.; Browner, R.F.

1988-03-01

365

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

PubMed

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

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

2012-07-01

366

Enrichment and Characterization of Histones by 2D-Hydroxyapatite/Reversed-Phase Liquid Chromatography Mass Spectrometry  

PubMed Central

Here we report a novel two-dimensional LC-MS method that combines offline hydroxyapatite (HA) chromatography with online reversed-phase liquid chromatography mass spectrometry (HA/RP LC-MS). The 2D-LC-MS method was used to enrich and characterize histones and their posttranslational modifications. The 2D HA/RP LC-MS approach separates histones based on their relative binding affinity to DNA and relative hydrophobicity. HA/RP separations showed improvement in the number of histone isoforms detected as compared with 1D reversed-phase LC-MS of acid extracted histones. The improved histone fractionation resulted in better detection of lower abundant histone variants as well as their posttranslationally modified isoforms. Histones eluted from the HA/RP in the following order: H1, H2A/H2B heterodimers followed by H3/H4 heterotetramers, as predicted from their spatial organization in nucleosomes for binding affinity to DNA. Comparison between HA purified and acid-extracted histones revealed similar histone profiles with the exception that the HA fractions showed a greater number of H1 isoforms. Two elution conditions were also examined: batch elution and salt-gradient elution. While both elution techniques were able to sufficiently fractionate the histones, the salt-gradient approach has the most potential for purification of selected histone isoforms.

Su, Xiaodan; Jacob, Naduparambil K.; Amunugama, Ravindra; Hsu, Pang-Hung; Fishel, Richard; Freitas, Michael A.

2009-01-01

367

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

PubMed

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

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

2011-10-28

368

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

PubMed

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

Jiang, H

1997-07-01

369

Quantification of acetylcholine, an essential neurotransmitter, in brain microdialysis samples by liquid chromatography mass spectrometry.  

PubMed

Chemical neurotransmission has been the subject of intensive investigations in recent years. Acetylcholine is an essential neurotransmitter in the central nervous system as it has an effect on alertness, memory and learning. Enzymatic hydrolysis of acetylcholine in the synaptic cleft is fast and quickly metabolizes to choline and acetate by acetylcholinesterase. Hence the concentration in the extracellular fluid of the brain is low (0.1-6 nm). Techniques such as microdialysis are routinely employed to measure acetylcholine levels in living brain systems and the microdialysis sample volumes are usually less than 50 microL. In order to develop medicine for the diseases associated with cognitive dysfunction like mild cognitive impairment, Alzheimer's disease, schizophrenia and Parkinson's disease, or to study the mechanism of the illness, it is important to measure the concentration of acetylcholine in the extracellular fluid of the brain. Recently considerable attention has been focused on the development of chromatographic-mass spectrometric techniques to provide more sensitive and accurate quantification of acetylcholine collected from in-vivo brain microdialysis experiments. This review will provide a brief overview of acetylcholine biosynthesis, microdialysis technique and liquid chromatography mass spectrometry, which is being used to quantitate extracellular levels of acetylcholine. PMID:19877295

Nirogi, Ramakrishna; Mudigonda, Koteshwara; Kandikere, Vishwottam; Ponnamaneni, Ranjithkumar

2010-01-01

370

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

PubMed

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

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

2000-10-27

371

Identification of Components in Organic Films by Coupled Liquid Chromatography-Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Recent studies have shown that viscous organic films of unknown composition develop on the surface of solutions containing propanal, glyoxal and high concentrations of sulfuric acid. These films, the products of significant contributors to atmospheric chemistry and particle composition, are theorized to have major implications in real world settings. Surface films that form on aerosol particles can alter cloud formation, diurnal patterns, and the optical properties of the atmosphere. In order to predict these chemical and physical properties, the components of both the films and the solutions that form them are studied via coupled Liquid Chromatography-Mass Spectrometry (LC-MS). Spectra reveal the presence of a varying range of product masses (75 m/z to ~ 700 m/z) within these film-making solutions. This suggests the formation of oligomers and/or complex products from the simple starting components. As such, much of the chemistry involved in this process results from a series of acid-catalyzed mechanisms. This presentation will focus on detailed interpretation of the LC-MS results with the goal of determining the building-blocks for the oligomers and identifying as many of the molecules present in the films and the reaction solutions as possible.

Tell, K. A.; Gross, D. S.; van Wyngarden, A. L.; Iraci, L. T.

2008-12-01

372

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

PubMed

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

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

2005-04-12

373

Bioassay- and liquid chromatography/mass spectrometry-guided acetylcholinesterase inhibitors from Picriafel-terrae  

PubMed Central

Background: Picria fel-terrae is a traditional Chinese medicine. Materials and Methods: A new approach to the search for acetylcholinesterase (AChE) inhibitors from Picria fel-terrae is presented. Results: Bioassay- and LC-MS-guided fractionation of the ethyl acetate extract was from traditional Chinese medicine P.fel-terrae. Following primary extraction, the ethyl acetate extracts fraction of P.fel-terrae showed strong AChE inhibitory activities. So the sample was separated using highperformance liquid chromatography (HPLC). The effluent was split towards two identical 96-well fraction collectors, and the presence of the biologically interesting portion and chromatographic fractions could be readily detected by analyzing selected ion chromatograms through an electrophoresis-electrospray ionization mass spectrometry (ESIMS) system for accurate mass measurement. One 96-well plate was used for a bioassay (AChE-inhibitory assay) and detected the bioactivity and position of the relevant peak in the chromatogram. The positive well in the second 96-well plate was used for identification by LC-(+) ESIMS. Conclusion: As abovementioned, the AChE inhibitory constituents from P.fel-terrae by LC-bioassay-ESIMS were rapid identified. Liquid chromatography/ mass spectrometry (LC-MS) screening detected the presence of six active compounds, identified as picfeltarraenin IA (1), picfeltarraenin IB (2), picfeltarraenin IV (3), picfeltarraenin X (4), picfeltarraenin XI (5), and one unknown compound. The structures were further determined by 13C NMR. The six compounds expressed stronger AChE inhibition than the known AChE inhibitorTacrine. Above all, the value of this LC-bioassay-ESIMS methodology is highlighted by the finding and structure elucidation of the active constituents from many other structural families of natural products.

Wen, Lu; Wei, Qiqiu; Chen, Gang; Liu, Fan; Zhang, Shichang; You, Tinghuo

2013-01-01

374

Simultaneous determination of bovine ?-lactalbumin and ?-lactoglobulin in infant formulae by ultra-high-performance liquid chromatography–mass spectrometry  

Microsoft Academic Search

A reliable ultra-high-performance liquid chromatography–mass spectrometry method for simultaneous determination of bovine ?-lactalbumin (?-La) and ?-lactoglobulin (?-Lg) was developed. Compared to the previous methods, the developed approach with mass spectrometer operated in selected area monitoring mode offered increased speed and enhanced lower detection limit. A linear gradient mobile phase, consisting of (A) water containing 0.1% trifluoroacetic acid (TFA) and (B)

Yiping Ren; Zheng Han; Xiaojun Chu; Jingshun Zhang; Zengxuan Cai; Yongjiang Wu

2010-01-01

375

Determination of carbamate residues in fruits and vegetables by matrix solid-phase dispersion and liquid chromatography–mass spectrometry  

Microsoft Academic Search

Thirteen carbamates were analysed in orange, grape, onion and tomatoes by matrix solid-phase dispersion (MSPD) followed by liquid chromatography–mass spectrometry (LC–MS). Electrospray (ES) and atmospheric pressure chemical ionisation (APCI) were compared and both gave similar results in terms of sensitivity and structural information because at 20 V fragmentor voltages the fragmentation is minimal. The efficiency of different solid-phases (C18, C8,

M Fernández; Y Picó; J Mañes

2000-01-01

376

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

Microsoft Academic Search

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

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

1982-01-01

377

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

PubMed Central

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

Bacchin, Paolo; Robertiello, Andrea; Viglia, Aurelio

1974-01-01

378

Particle beam liquid chromatography-mass spectrometry of triphenylmethane dyes: application to confirmation of malachite green in incurred catfish tissue  

Microsoft Academic Search

Eight triphenylmethane dyes (malachite green, leucomalachite green, gentian violet, leucogentian violet, brilliant green, pentamethyl gentian violet, N?,N?-tetramethyl gentian violet and N?,N?-tetramethyl gentian violet) have been characterized by particle beam liquid chromatography-mass spectrometry. The electron ionization spectra obtained of these dyes by this technique exhibit similar fragmentation, with the formation of phenyl and substituted phenyl radicals, and loss of alkyl groups

Sherri B. Turnipseed; José E. Roybal; Heidi S. Rupp; Jeffrey A. Hurlbut; Austin R. Long

1995-01-01

379

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

380

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

Microsoft Academic Search

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

Myriam Medina-Vera

1996-01-01

381

The future of liquid chromatography-mass spectrometry in metabolic profiling and metabolomic studies for biomarker discovery  

Microsoft Academic Search

The future utility of liquid chromatography-mass spectrometry (LC-MS) in metabolic profiling and metabolomic studies for biomarker discover will be discussed, beginning with a brief description of the evolution of metabolomics and the utilization of the three most popular analytical platforms in such studies: NMR, GC-MS, and LC-MS. Emphasis is placed on recent developments in high-efficiency LC separations and sensitive electrospray

Thomas O. Metz; Qibin Zhang; Jason S. Page; Yufeng Shen; Stephen J. Callister; Jon M. Jacobs; Richard D. Smith

2007-01-01

382

Critical review of the application of liquid chromatography\\/mass spectrometry to the determination of pesticide residues in biological samples  

Microsoft Academic Search

A critical review is made on the use of hyphenated liquid chromatography\\/mass spectrometry (LC–MS) for the identification and quantification of pesticides and their metabolites in human biosamples (whole blood, plasma, serum and urine). The first applications of LC–MS in this field began in the early 1990s. Since then, increasing interest has been shown in applying this powerful technique, with most

F. Hernández; J. V. Sancho; O. J. Pozo

2005-01-01

383

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

Microsoft Academic Search

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

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

2007-01-01

384

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

Microsoft Academic Search

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

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

2011-01-01

385

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

Microsoft Academic Search

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

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

2011-01-01

386

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

Microsoft Academic Search

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

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

2000-01-01

387

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

Microsoft Academic Search

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

Thomas Heberer; Hans-Juergen Stan

1997-01-01

388

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

Microsoft Academic Search

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

Z. Ežerskis; Z. Jusys

2002-01-01

389

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

Microsoft Academic Search

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

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

2005-01-01

390

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

Microsoft Academic Search

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

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

391

Determination of macrolide antibiotics in meat and fish using pressurized liquid extraction and liquid chromatography–mass spectrometry  

Microsoft Academic Search

We developed a method for determining the quantities of seven macrolide antibiotics in meat and fish by using pressurized liquid extraction (PLE) and liquid chromatography–mass spectrometry with electrospray ionization (LC–(ESI)MS). The PLE was optimized with regard to solvents, temperature, pressure, extraction time and number of cycles. The optimum conditions were: methanol as the extraction solvent; a temperature of 80°C; a

Houda Berrada; Francesc Borrull; Rosa Maria Marcé

2008-01-01

392

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

Microsoft Academic Search

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

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

2007-01-01

393

Simple method for the determination of benzodiazepines in human body fluids by high-performance liquid chromatography–mass spectrometry  

Microsoft Academic Search

Three benzodiazepines, etizolam, brotizolam and lorazepam, have been analyzed from human plasma and urine samples by high-performance liquid chromatography–mass spectrometry (HPLC–MS) with a new polymer column (MSpak GF), which enabled direct injection of crude biological samples. The recoveries of the three benzodiazepines spiked into plasma and urine were 81.7–90.7 and 78.7–91.5%, respectively. The regression equations for the three benzodiazepines showed

X.-P Lee; T Kumazawa; J Sato; Y Shoji; C Hasegawa; C Karibe; T Arinobu; H Seno; K Sato

2003-01-01

394

High-throughput determination of theophylline and caffeine in human serum by conventional liquid chromatography-mass spectrometry  

Microsoft Academic Search

Automated high-performance liquid chromatography\\/mass spectrometry (HPLC-MS) with backflush column-switching was established\\u000a for ultra-fast determination of theophylline and caffeine. A 400-?l portion of serum sample diluted with ultrapure water was\\u000a injected and transferred to an Oasis HLB cartridge used as a precolumn for extraction. After switching the valves, the analytes\\u000a trapped in the precolumn were eluted in the backflush mode and

Tetsuya Arinobu; Hideki Hattori; Takeshi Kumazawa; Xiao-Pen Lee; Yoko Mizutani; Takao Katase; Sadao Kojima; Takayuki Omori; Rina Kaneko; Akira Ishii; Hiroshi Seno

2009-01-01

395

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

Microsoft Academic Search

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

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

2011-01-01

396

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

PubMed Central

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

Bengtsson, Goran; Annadotter, Helene

1989-01-01

397

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

PubMed

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

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

2011-09-01

398

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

PubMed

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

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

2001-10-01

399

Recent studies of the electrospray ionisation behaviour of selected drugs and their application in capillary electrophoresis–mass spectrometry and liquid chromatography–mass spectrometry  

Microsoft Academic Search

This review is concerned with recent studies of electrospray ionisation-mass spectrometry (ESI-MS) of selected small molecular mass drugs and their application in qualitative and quantitative analytical methods using the techniques liquid chromatography mass spectrometry (LC–ESI-MS) and capillary electrophoresis mass spectrometry (CE–ESI-MS). The publications reviewed are taken from the Web of Knowledge database for the year 2006. The drugs have molecular

W. Franklin Smyth; Virginia Rodriguez

2007-01-01

400

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

PubMed

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

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

1990-09-15

401

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

National Technical Information Service (NTIS)

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

D. A. Netzel F. D. Guffey

1987-01-01

402

[Screening of the active ingredients in natural products by capillary electrophoresis and high performance liquid chromatography-mass spectrometry].  

PubMed

A new strategy for screening the crude natural extracts and quickly identifying the bioactive compounds was developed. In combination with high performance liquid chromatography-mass spectrometry (HPLC-MS) , the biologically active compounds, such as the enzyme i n the crude natural extract ca n be quickly identified by capillary electrophoresis (CE) -based activity assay. The crude natural extracts were assayed by a CE-based enzyme inhibitor screening method, and the active extract was isolated by HPLC-MS/MS with a semipreparative column. Then, each eluted component was assayed again with the CE-based assay method. Finally, the structures of the identified active compounds were elucidated by MS/MS analysis. Acetylcholinesterase ( ACHE), its substrate acetylthiocholine chloride ( AThCh), as well as the crude extract of Rhizoma coptidis were utilized for the proof of the methodology. Seven isoquinoline alkaloids, namely jatrorrhizine, epiberberine, columbamine, coptisine, corysamine, palmatine and berberine were identified to be active as the inhibitors of ACHE. Their IC50 values were 40, 442, 38, 182, 419, 54 and 16 micromol/L, respectively. Compared with the traditional screening methods, the method is characterized with several advantages, such as extremely low sample and reagent consumption, high speed of analysis, high sensitivity of detection, high throughput in terms of preparation of the natural products by HPLC. Overall, the results demonstrate that the method is valuable for the screening of the bioactive compounds in the crude natural extracts. PMID:24164032

Zhang, Yanmei; Kang, Jingwu

2013-07-01

403

[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

404

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

PubMed

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

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

2002-05-01

405

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

PubMed

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

Li, Meigui; Li, Yuanxing; Mao, Liqiu

2007-01-01

406

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

PubMed

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

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

2010-02-06

407

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

PubMed

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

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

2012-09-20

408

IDENTIFICATION OF POLAR DRINKING WATER DISINFECTION BY-PRODUCTS USING LIQUID CHROMATOGRAPHY - MASS SPECTROMETRY  

EPA Science Inventory

A qualitative method using 2,4-dinitrophenylhydrazine (DNPH) derivatization followed by analysis with liquid chromatography (LC)/negative ion-electrospray mass spectrometry (MS) was developed for identifying polar aldehydes and ketones in ozonated drinking water. This method offe...

409

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

PubMed

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

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

2013-07-31

410

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

PubMed

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

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

2001-03-01

411

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

PubMed

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

Chou, Chi-Chi; Lee, Maw-Rong

2005-01-28

412

Improved detection of multi-phosphorylated peptides in the presence of phosphoric acid in liquid chromatography/mass spectrometry  

SciTech Connect

In contrast to lower phosphorylation states (e.g., the tryptic monophosphopeptide FQpSEEQQQTEDELQDK from bovine -casein), the specific detection of multi-phosphorylated peptides (e.g. the tetraphosphopeptide RELEELNVPGEIVEpSLpSpSpSEESITR from tryptic digestion of bovine -casein) has often been problematic for liquid chromatography-mass spectrometry analysis due to their high affinity for adsorption to exposed surfaces. We observed an enhancement in the overall detection of phosphopeptides upon addition of phosphoric acid (0.1% to 1.0%) to the sample solution; a 10-fold increase in sensitivity was measured for the detection of two tryptic phosphopeptides as well as a significant improvement in the detection of the tetraphosphopeptide. Using capillary LC with an ion trap tandem mass spectrometer for detection and identification, the achievable detection limits were 50 fmol and 50 pmol for the monophosphopeptide and the tetraphosphopeptide, respectively. Phosphoric acid is believed to act as a blocking agent to available silanol groups on both the silica capillary surface and the C-18-bonded silica surface.

Kim, Jeongkwon; Camp, David G.; Smith, Richard D.

2004-02-18

413

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

414

[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

415

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

SciTech Connect

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

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

1998-05-22

416

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

PubMed

Tuberculosis (TB) remains a major international health problem. Rapid differentiation of Mycobacterium tuberculosis complex (MTB) from non-tuberculous mycobacteria (NTM) is critical for decisions regarding patient management and choice of therapeutic regimen. Recently we developed a 20-compound model to distinguish between MTB and NTM. It is based on thermally assisted hydrolysis and methylation gas chromatography-mass spectrometry and partial least square discriminant analysis. Here we report the validation of this model with two independent sample sets, one consisting of 39 MTB and 17 NTM isolates from the Netherlands, the other comprising 103 isolates (91 MTB and 12 NTM) from Stellenbosch, Cape Town, South Africa. All the MTB strains in the 56 Dutch samples were correctly identified and the model had a sensitivity of 100% and a specificity of 94%. For the South African samples the model had a sensitivity of 88% and specifi