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PubMed2002

Headspace solid-phase microextraction in combination with gas chromatography and tandem mass spectrometry for the determination of organochlorine and organophosphorus pesticides in whole numan blood.

A method for the determination of several organochlorine and organophosphorus pesticides in human whole blood samples was developed. The combination of solid-phase microextraction in headspace mode with gas chromatography with tandem mass spectrometry allowed the determination of 11 selected pesticides at ppb levels, minimizing the sample treatment. Quantitation was carried out by means of calibration curves prepared in blood using labelled surrogate/internal standards. The method showed good linearity between 1 and 50 ng ml(-1) (0.5-25 ng ml(-1) for HCB) using second-order calibration curves. Precision was found to be better than 20% at the three concentration levels assayed in the range of ng ml(-1). The detection limits obtained were in the range 0.02-0.7 ng ml(-1), except for p,p'-DDT (3 ng ml(-1)). The developed procedure was applied to blood and serum samples obtained from agricultural workers. HCB. beta-HCH and p,p'-DDE were most frequently detected in the samples analyzed.

Gas Chromatography-Mass Spectrometry↗

PubMed2003

Application of low-temperature glassy carbon-coated macrofibers for solid-phase microextraction analysis of simulated breath volatiles.

With increasing interest in the detection of disease-related volatile organic compounds (VOCs) found in human breath, breath analysis could prove to be a very useful diagnostic tool, especially for the early detection of lung cancer. Solid-phase microextraction (SPME) is a technique well suited for breath analysis and has been applied to studying VOCs in the nanomolar concentration range. However, many compounds of interest in human breath are excreted at picomolar concentrations and may be unsuitable for analysis using conventional SPME sorbent phases. To extend the concentration range of conventional SPME, a novel 4-cm-long, low-temperature glassy carbon (LTGC) macrofiber was developed. The LTGC SPME macrofibers were used to extract five lung cancer-related VOCs (2-methylheptane, styrene, propylbenzene, decane, undecane) at conditions simulating human breath, and they were analyzed via gas chromatography/mass spectrometry. Results show that detection limits are lower using the SPME macrofibers compared to a conventional SPME fiber, in the low- to sub-picomolar range for the compounds of interest, which should be adequate for the analysis of these compounds in human breath. Also, the LTGC SPME macrofibers demonstrate significantly greater extraction efficiencies, sensitivity, and peak identification accuracy compared to that of commercial PDMS/DVB fibers without excessive chromatographic peak broadening. The use of SPME macrofibers broadens the potential range of application of SPME where the rapid extraction of very low levels of volatile compounds is required.

Alkanes↗

PubMed2002

Comparison of different methods: static and dynamic headspace and solid-phase microextraction for the measurement of interactions between milk proteins and flavor compounds with an application to emulsions.

Interactions between 10 aroma compounds from different chemical classes and 5 mixtures of milk proteins have been studied using static or dynamic headspace gas chromatography and solid-phase microextraction (SPME). Static headspace analysis allows the quantification of the release of only the most abundant compounds. Dynamic headspace analysis does not allow the discrimination of flavor release from the different protein mixtures, probably due to a displacement of headspace equilibrium. By SPME analysis and quantification by GC-MS (SIM mode) all of the volatiles were quantified. This method was optimized to better discriminate aroma release from the different milk protein mixtures and then from oil/water emulsions made with these proteins. The highest difference between the release in different proteins was observed for ethyl hexanoate, which has a great affinity for beta-lactoglobulin. Ethyl hexanoate is thus less released from models and emulsions containing this protein.

Caproates↗

PubMed2003

Quantitation of (R)- and (S)-linalool in beer using solid phase microextraction (SPME) in combination with a stable isotope dilution assay (SIDA).

A stable isotope dilution assay (SIDA) was developed for the quantitation of both linalool enantiomers using synthesized [2H(2)]R/S-linalool as the internal standard. For enrichment of the target compound from beer, a solid phase microextraction method (SPME) was developed. In comparison to the more time-consuming extraction/distillation cleanup of the beer samples, the results obtained by SPME/SIDA were very similar, even under nonequilibration conditions. Analysis of five different types of beer showed significant differences in the linalool concentrations, which were clearly correlated with the intensity of the hoppy aroma note as evaluated by a sensory panel. In addition, significant differences in the R/S ratios were measured in the beers. The SPME/SIDA yielded exact data independently from headspace sampling parameters, such as exposure time or ionic strength of the solution.

Acyclic Monoterpenes↗

PubMed2004

Determination of chloroanisole compounds in red wine by headspace solid-phase microextraction and gas chromatography-mass spectrometry.

The objectives of this study, were the development and validation of an analytical method for the determination of 2,4,6-trichloroanisole (TCA), 2,3,4,6-tetrachloroanisole (TeCA) and pentachloroanisole (PCA) in red wine by headspace solid-phase microextraction and GC-MS as well as the application of the optimized and validated method for the quatification of chloroanisoles in different red wines from Navarra. To carry out this study, the extraction variables have been optimized. The fiber and the experimental design selected permit the determination of low analyte concentrations (ng/L) with good accuracy (<5%). Moreover, an analytical method for the determination of TCA and TeCA in wine by GC-MS has been validated. The results obtained in the validation step, recovery values, detection and quantitative limits, and precision were acceptable for all the analytes in the ranges of concentration studied (<5% and <10% for TCA and TeCA, respectively). This method has been used as an analytical method for the quantification of TCA and TeCA in red wine samples that were selected for this study, yielding good results.

Anisoles↗

PubMed2005

Determination of mono- to octachlorobiphenyls in fish oil using florisil adsorption followed by headspace solid-phase microextraction and gas chromatography with time-of-flight mass spectrometric detection.

A simple and reliable method for the determination of polychlorinated biphenyls (PCBs) from mono- to octachlorobiphenyls in fish oil for dietary supplement is described. The method combines Florisil clean up and headspace solid-phase microextraction on 65 microm polydimethylsiloxane-divinylbenzene (PDMS-DVB). Analyte detection was carried out using GC-time-of-flight mass spectrometry (GC-TOF-MS). Fifty three PCB congeners including the seven indicator PCBs (IUPAC Nos. 28, 52, 101, 118, 138, 153 and 180) were analyzed. Under optimal conditions, the method detection limit (MDL) of each congener in the range from 0.8 to 31 ng/g was found. A certified reference material (BCR-349) was analyzed and it showed good agreement with the certified data.

Adsorption↗

PubMed2006

Analysis of estrogens in environmental waters using polymer monolith in-polyether ether ketone tube solid-phase microextraction combined with high-performance liquid chromatography.

A simple, rapid and sensitive on-line method for simultaneous determination of four endocrine disruptors (17beta-estradiol, estriol, bisphenol A and 17alpha-ethinylestradiol) in environmental waters was developed by coupling in-tube solid-phase microextraction (SPME) to high-performance liquid chromatography (HPLC) with fluorescence detection (FLD). A poly(acrylamide-vinylpyridine-N,N'-methylene bisacrylamide) monolith, synthesized inside a polyether ether ketone (PEEK) tube, was selected as the extraction medium. To achieve optimum extraction performance, several parameters were investigated, including extraction flow-rate, extraction time, and pH value, inorganic salt and organic solvent content of the sample matrix. By simply filtered with nylon membrane filter and adjusting the pH of samples to 6.0 with phosphoric acid, the sample solution then could be directly injected into the device for extraction. Low detection limits (S/N=3) and quantification limits (S/N=10) of the proposed method were achieved in the range of 0.006-0.10 ng/mL and 0.02-0.35 ng/mL from spiked lake waters, respectively. The calibration curves of four endocrine disruptors showed good linearity ranging from quantification limits to 50 ng/mL with a linear coefficient R(2) value above 0.9913. Good method reproducibility was also found by intra- and inter-day precisions, yielding the RSDs less than 12 and 9.8%, respectively. Finally, the proposed method was successfully applied to the determination of these compounds in several environmental waters.

Benzophenones↗

PubMed2006

Simple and sensitive determination of Delta(9)-tetrahydrocannabinol, cannabidiol and cannabinol in hair by combined silylation, headspace solid phase microextraction and gas chromatography-mass spectrometry.

A new method for determination of Delta(9)-tetrahydrocannabinol (THC), cannabidiol (CBD) and cannabinol (CBN) in hair based on alkaline hair hydrolysis, extraction by iso-octane, combined derivatization with N,O-bis-(trimethylsilyl)-trifluoroacetamide and headspace solid phase microextraction of the extract residue, and gas chromatography-mass spectrometry was developed and evaluated. The limits of detection of the three compounds were 0.01-0.02 ng/mg. The method was routinely applied to more than 250 hair samples. In 77 positive samples, the concentrations ranged from LOD to 4.2 ng/mg for THC (mean 0.49 ng/mg), to 12.1 ng/mg for CBD (mean 0.37 ng/mg) and to 0.85 ng/mg for CBN (mean 0.12 ng/mg) using a sample amount of 30 mg. The frequently observed increase of the segmental drug concentrations from proximal to distal is explained by progressive accumulation in the hair shaft from sebum or side stream smoke.

Calibration↗

PubMed2000

Headspace solid-phase microextraction method for determining 3-alkyl-2-methoxypyrazines in musts by means of polydimethylsiloxane-divinylbenzene fibres.

A method for determining 2-methoxypyrazine, 3-methyl-, 3-ethyl-, 3-isopropyl-, 3-sec.-butyl- and 3-isobutyl-2-methoxypyrazine in musts is described. It involves headspace solid-phase microextraction (SPME) and determination by capillary gas chromatography using nitrogen-phosphorous detection. Pyrazines were satisfactorily separated under isothermal conditions, and quantification was carried out using 3-isopropyl-2-ethoxypyrazine as the internal standard. Ionic strength, time and temperature were studied in order to make SPME as efficient as possible. The developed method enabled detection limits at the 0.1 ng(-1) levels for some of the analytes. The method was successfully applied to identify and quantify different 3-alkyl-2-methoxypyrazines in experimental musts of Cabernet Sauvignon and Merlot. Their evolution during the ripening was also monitored.

Osmolar Concentration↗

PubMed1999

Use of solid-phase microextraction for the analysis of bisphenol A and bisphenol A diglycidyl ether in food simulants.

A new method has been developed to simultaneously analyse bisphenol A (BPA) and bisphenol A diglycidyl ether (BADGE) in aqueous based food simulants. The method consists on direct immersion solid-phase microextraction (SPME) of the analytes from the liquid matrix and subsequent chromatographic analysis by gas chromatography-mass spectrometry. Using the proposed method, a whole analysis (including chromatographic step) can be completed in less than 40 min, with minimum sample handling. The SPME method shows good analytical performance for simultaneous BPA and BADGE analysis, except for BADGE determination in the aqueous alcohol (simulant C) solution. Detection limits ranging from 0.1 to 2.0 ng/g for BPA and from 13 to 15 ng/g from BADGE were obtained, with a linear range from the low-ng/g to several-microg/g range for BPA and from 0.1 microg/g to 40 microg/g for BADGE. A possible optimisation method has been also developed and introduced.

Benzhydryl Compounds↗

PubMed2003

Detection and prediction of hydrolytic rancidity in milk by multiple regression analysis of short-chain free Fatty acids determined by solid phase microextraction gas chromatography and quantitative flavor intensity assessment.

The objective was to establish a method for detecting and predicting hydrolytic rancidity in milk by correlating quantitative sensory data with individual short-chain free fatty acids (FFA) (C(4)-C(12)) in milk determined by solid phase microextraction and gas chromatography (SPME-GC). A FFA-based equation for determining rancid flavor intensities in milk was derived by stepwise regression analysis. A highly significant (p < 0.001) correlation coefficient (R (2)) of 0.84 indicated that rancidity scores were dependent on FFA obtained by SPME-GC and that a good proportion of the variation in the rancidity scores was explained by the model. When rancidity scores were predicted for 19 commercial milks, one sample was found to be distinctly rancid by the statistical model and by the trained sensory panel. The rest of the samples were found to be nonrancid by either method. Thus, the predicting power of the model was shown because there was 100% correct flavor classification for the samples tested.

Animals↗

PubMed2006

Solid phase microextraction with gas chromatography-mass spectrometry: a very rapid method for identification of volatile organic compounds emitted by Carum copticum.

The investigation of flower scent represents an important field of modern biological research which is directed towards special theories of biological recognition. The headspace solid phase microextraction coupled with gas chromatography-mass spectrometry was used to identify the volatile components of Carum copticum (C. copticum) cultivated in Iran. The compounds were identified according to their retention indices and mass spectra (EI, 70 eV). The effects of different parameters, such as the desorption time, the extraction temperature, the sample mass, the addition of salt, the pre-equilibration time and the extraction time, on the extraction efficiency were investigated. The optimized conditions were: the desorption time, 2 min; the extraction temperature, 58 degrees Celsius; the sample mass, 1.000 g in 4.0 mL 2.0 M NaCl solution; the pre-equilibration time, 25 min; the extraction time, 20 min. Finally, ten components were identified in the volatile components of C. copticum. The major components of C. copticum were thymol (68.2%), gamma-terpinene (13.9%), p-cymene (11.6%), myrcene (1.0%) and beta-pinene (0.6%). Precision of the proposed method is good and %RSD less than 14 was obtained.

Carum↗

PubMedDate not supplied

Use of solid-phase microextraction (SPME) for the determination of methadone and its main metabolite, EDDP, in plasma by gas chromatography-mass spectrometry.

A simple, rapid method for the determination of methadone and its metabolite 2-ethylene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in plasma using solid-phase microextraction (SPME) and gas chromatography-mass spectrometry is proposed. A 100-microm polydimethylsiloxane film fiber was exposed by immersion for 30 min in a diluted plasma solution (1:4 with buffer pH 9) containing both compounds and an internal standard (proadifen). Calibration curves were linear over the concentration range 50-2000 ng/mL. The analysis time was 45 min per sample. The determination of methadone and EDDP was subject to no interference. The performance of SPME was compared with that of liquid-liquid extraction, obtaining lower limits of detection for EDDP. The method using the two extraction procedures was applied to 10 plasma samples from methadone-treated patients.

Calibration↗

PubMedDate not supplied

Determination of plastic monomers in water by solid-phase microextraction coupled with liquid chromatography.

A method is presented for the determination of 2 major plastic monomers, terephthalic acid and vinyl acetate, which are widely used to manufacture plastics that come in contact with foods. The analytes are extracted from aqueous solution by using solid-phase microextraction, followed by quantitation by liquid chromatography (LC) with UV detection. Multivariate optimization was applied and is described. The optimized method has linear ranges of 5-150 microg/g for terephthalic acid and 7.5-100 microg/g for vinyl acetate. Coefficients of variation at a spiking level of 20 microg/g were 13.6% for terephthalic acid and 3.1% for vinyl acetate; detection and quantitation limits were 0.59 and 1,99 microg/g, respectively, for terephthalic acid and 1.56 and 5.20 microg/g, respectively, for vinyl acetate. The characteristics of both the extraction technique and its coupling with LC are described and discussed.

Chromatography, Liquid↗

PubMed2006

Simple approach for the determination of brominated flame retardants in environmental solid samples based on solvent extraction and solid-phase microextraction followed by gas chromatography-tandem mass spectrometry.

A viable approach for the analysis of polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) in sewage sludge samples is presented in this paper. The proposed method combines ultrasound-assisted extraction (UAE) of the solid sample and headspace solid-phase microextraction (HS-SPME) of the obtained extract, followed by gas chromatography coupled to tandem mass spectrometry (GC-MS-MS) analysis. Different parameters affecting the extraction process are evaluated and optimized. The addition of a small amount of Florisil to the sample during UAE provides a significant improvement of the chromatographic background and, at the same time, a much more efficient HS-SPME. Extensive method validation is performed using real sewage sludge samples. The proposed method exhibits good performance in terms of linearity and precision, with recoveries exceeding 92% and limits of detection in the sub ng g(-1) level. Practical applicability is demonstrated through the analysis of real contaminated sewage sludge and sediment samples in which some of the target PBDEs are detected and quantified. This proposed combined methodology represents a large time-saving when compared to other classic multi-step solvent extraction methods and it constitutes a suitable approach for the analysis of the target compounds in environmental complex solid samples.

Bromine↗

PubMed2000

Determination of gamma-hydroxybutyric acid (GHB) in plasma and urine by headspace solid-phase microextraction and gas chromatography/positive ion chemical ionization mass spectrometry.

A new method for the qualitative and quantitative analysis of gamma-hydroxybutyric acid (GHB) in plasma and urine samples is described. It involves the conversion of GHB to gamma-butyrolactone (GBL), its subsequent headspace solid-phase microextraction (SPME), and detection by gas chromatography/positive ion chemical ionization mass spectrometry (GC/PICI-MS), using D(6)-GBL as internal standard. The assay is linear over a plasma GHB range of 1-100 microg/mL (n = 5, r = 0.999) and a urine GHB range of 5-150 microg/mL (n = 5, r = 0. 998). Relative intra- and inter-assay standard deviations, determined for plasma and urine samples at 5 and 50 microg/mL, are all below 5%. The method is simple, specific and reasonably fast. It may be applied for clinical and forensic toxicology as well as for purposes of therapeutic drug monitoring.

4-Butyrolactone↗

PubMed2006

Determination of semi-volatile priority pollutants in landfill leachates and sediments using microwave-assisted headspace solid-phase microextraction.

The present work was focused on the development of a simple method aimed at the determination of 12 polycyclic aromatic hydrocarbons (PAHs) and 15 polychlorinated biphenyls (PCBs) in landfill leachates and sediments by adapting a domestic microwave oven to perform microwave-assisted headspace solid-phase microextraction (MA-HS-SPME) followed by gas chromatographic separation and tandem mass spectrometric detection. Good linearity was observed within the concentration range studied; detection limits ranged from 0.1 ng/l to 7 ng/l for PCBs and from 5 ng/l to 926 ng/l for PAHs. Concerning precision, the relative standard deviations obtained were, on average for the leachate and sediment samples analysed, 18% for PCBs and 20% for PAHs. Average recovery values were 37% and 76% for PCBs, and 58% and 48% for PAHs, respectively, for the leachate and reference sediment studied. The method allows the determination of PAHs and PCBs in landfill leachates and sediments, avoiding clean-up steps and the consumption of organic solvents.

Journal Article↗

PubMed2000

Monitoring organochlorine pesticides from landfill leachates by gas chromatography-electron-capture detection after solid-phase microextraction.

Landfill leachates contain significant amounts of organic carbon, nitrogen and heavy metals as well as other specific trace organic compounds like organochlorine pesticides. In this study a simple and reliable methodology was improved to detect organochlorine pesticides in leachate samples by using a previous solid-phase microextraction procedure [with a 100 microm poly(dimethylsiloxane) fiber] and chromatographic analysis by GC-electron-capture detection. The extraction time, temperature, ionic strength of the solution and sampling of the headspace were the parameters studied. Reproducibility achieved values below 20% RSD, and standard addition was used for pesticides confirmation.

Chromatography, Gas↗