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Results for “Solid Phase Microextraction”

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PubMed2006

The extraction and analysis of 1,4-dioxane from water using solid-phase microextraction coupled with gas chromatography and gas chromatography-mass spectrometry.

In this study, two methods are developed for the extraction of 1,4-dioxane (dioxane) from water using 80-microm carboxen-polydimethylsiloxane solid-phase microextraction fibers followed by either gas chromatography (GC)-flame ionization detection (FID) or GC-mass spectrometry (MS). With GC-FID, the lower limit of detection (LOD) for 1,4-dioxane is 2.5 microg/L (ppb) with a linear range of 5 to 10,000 microg/L, obtained by immersing the fiber in the sample for 20 min with agitation. Using GC-MS, the lower limit of quantitation is 0.5 microg/L, and the LOD is 0.25 microg/L. The upper linear range limit is 100 microg/L. Samples are extracted in 20 min using either heated headspace with agitation or direct immersion with agitation.

Dioxanes↗

PubMed2004

Components detected by means of solid-phase microextraction and gas chromatography/mass spectrometry in the headspace of artisan fresh goat cheese smoked by traditional methods.

The study of the headspace components of fresh smoked goat cheese, was carried out by means of solid-phase microextraction using a polyacrylate fiber followed by gas chromatography/mass spectrometry. The samples studied were six artisan Palmero cheeses manufactured following traditional methods and smoked using pine needles. The cheese regions studied were exterior, interior, and a cross section. In total, more than 320 components were detected, the exterior region being the richest in components, among which were acids, alcohols, esters, hydrocarbons, aldehydes, ketones, furan and pyran derivatives, terpenes and sesquiterpenes, nitrogen derivatives, phenol, guaiacol and syringol derivatives, ethers, and others. In addition to typical cheese components, typical smoke components were also detected; these latter were present especially in the headspace of the exterior region and only those in significant concentrations in the exterior region were also detected in the interior. The main components were acids and phenolic derivatives. These latter compounds play an important role in the flavor of this cheese, and their relative proportions together with the presence of specific smoke components derived from pine leaves may be considered of interest in order to distinguish this cheese from others smoked with different vegetable matter.

Animals↗

PubMed2003

Solid-phase microextraction as a clean-up and preconcentration procedure for organochlorine pesticides determination in fish tissue by gas chromatography with electron capture detection.

The feasibility of developing a single-step clean-up, enrichment procedure for organochlorine pesticides (OCPs) in fish tissue samples based on solid-phase microextraction (SPME) was investigated. The general analytical methodology developed combines conventional solid-liquid extraction of the OCPs from the sample using an organic solvent with SPME over the organic extract followed by gas chromatography-electron-capture detection (GC-ECD) analysis. Experimental SPME conditions such as extraction time, temperature and matrix effects were optimised. Under optimised conditions, precision, linearity range, detection limits and accuracy were evaluated. Detection limits obtained for fish tissue samples were in the range of 0.1-0.7 ng g(-1). Good recoveries (over 70% in all cases) were achieved from samples spiked at a concentration level of 10 ng g(-1). The accuracy of the developed SPME-GC-ECD procedure in real samples has been verified by analysing, using the standard addition method, a certified reference material (CRM 430, OCPs in pork fat) with satisfactory results.

Animals↗

PubMed2001

Determination of midazolam in human plasma by solid-phase microextraction and gas chromatography/mass spectrometry.

A new method is described for the qualitative and quantitative analysis of midazolam, a short-acting 1,4-imidazole benzodiazepine, in human plasma. It involves a plasma deproteinization step, solid-phase microextraction (SPME) of midazolam using an 85-microm polyacrylate fiber, and its detection by gas chromatography/mass spectrometry (GC/MS) in selected ion monitoring (SIM) mode, using pinazepam as internal standard. The assay is linear over a midazolam plasma range of 1.5-300 ng/mL, relative intra- and inter-assay standard deviations at 5 ng/mL are below 7%, and the limit of detection is 1 ng/mL. The method is simple, fast and sufficiently sensitive to be applied in clinical and forensic toxicology as well as for purposes of therapeutic drug monitoring.

Anti-Anxiety Agents↗

PubMed2005

Determination of nonylphenol and octylphenol in paper by microwave-assisted extraction coupled to headspace solid-phase microextraction and gas chromatography-mass spectrometry.

A novel and simple method for the determination of active endocrine disrupter compounds (octylphenol OP, and nonylphenol NP) in paper using microwave-assisted extraction (MAE) and headspace solid-phase microextraction, coupled with gas chromatography-mass spectrometry has been developed. Parameters affecting the efficiency in the MAE process such as exposure time and extraction solvent were studied in order to determine operating conditions. The optimised method was linear over the range studied (1.25-125 microg kg(-1) for OP and 9.50-950 microg kg(-1) for NP) and showed good level of precision, with a RSD lower than 10% and detection limits at 0.10 and 4.56 microg kg(-1) for OP and NP, respectively. The results obtained from six different types of paper revealed the presence of the target compounds in all samples analysed, at levels ranging between 3 and 211 microg kg(-1).

Calibration↗

PubMed2005

Solid-phase microextraction for the determination of cocaine and cocaethylene in human hair by gas chromatography-mass spectrometry.

A method for the simultaneous determination of cocaine (COC) and cocaethylene (CE) in human hair was developed, using solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) as analytical technique to identify and quantify the drugs. Selected ion monitoring (SIM) mode was used to obtain higher sensitivity. The deuterated-labeled analogues were used as internal standards. The detector response was linear for the drugs studied over the range 0.4-15 ng/mg, with correlation coefficients higher than 0.995. The coefficients of variation oscillated between 0.65% and 14.18% and the accuracy was in the range from 0.73% to 11.20%. The limits of quantitation and detection were found to be acceptable. Finally, this method was applied to 15 hair samples from cocaine users, obtaining positive results in all cases. The mean concentrations were 5.39 ng/mg (range: 0.43-8.98 ng/mg) for cocaine and 1.11 ng/mg (range: 0.42-2.23 ng/mg) for cocaethylene.

Adult↗

PubMed2002

Analysis of polar pesticides in water and wine samples by automated in-tube solid-phase microextraction coupled with high-performance liquid chromatography-mass spectrometry.

A simple and sensitive method for the determination of polar pesticides in water and wine samples was developed by coupling automated in-tube solid-phase microextraction (SPME) to high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS). To achieve optimum performance, the conditions for both the in-tube SPME and the ESI-MS detection were investigated. In-tube SPME conditions were optimized by selecting the appropriate extraction parameters, especially the stationary phases used for SPME. For the compounds studied, a custom-made polypyrrole (PPY)-coated capillary showed superior extraction efficiency as compared to several commercial capillaries tested, and therefore, it was selected for in-tube SPME. The influence of the ethanol content on the performance of in-tube SPME was also investigated. It was found that the amount of pesticides extracted decreased with the increase of ethanol content in the solutions. The ESI-MS detection conditions were optimized as follows: nebulizer gas, N2 (30 p.s.i.; 1 p.s.i.=6894.76 Pa); drying gas, N2 (10 l/min, 350 degrees C); capillary voltage, 4500 V; ionization mode, positive; mass scan range, 50-350 amu; fragmentor voltage, variable depending on the ions selected. Due to the high extraction efficiency of the PPY coating and the high sensitive mass detection, the detection limits (S/N = 3) of this method for the compounds studied are in the range of 0.01 to 1.2 ng/ml, which are more than one order of magnitude lower than those of the previous in-tube SPME-HPLC-UV method. A linear relationship was obtained for each analyte in the concentration range of 0.5 to 200 ng/ml with MS detection. This method was applied to the analysis of phenylurea and carbamate pesticides in spiked water and wine samples.

Automation↗

PubMed2003

Evaluation of headspace solid-phase microextraction for the analysis of volatile carbonyl compounds in spirits and alcoholic beverages.

A method was developed for the determination of C1-C6 carbonyl compounds in alcoholic solutions using pentafluorobenzoxymation followed by headspace sampling solid-phase microextraction and subsequent analysis by GC with electron-capture detection. Experimental conditions-alcohol content, exposure time, temperature and sample agitation were optimised. In this method, a spirit or distilled alcoholic beverage is first adjusted to 20% (v/v) alcohol. Detection limits for particular aldehydes and ketone varied from 0.05 to 0.5 microg/l and relative standard deviation was between 2.3 and 20%. Generally, the method showed good linearity for the tested concentration range 8 microg/l-0.32 mg/l with regression coefficients ranging between 0.9434 and 0.9983. The method was applied to the analysis of real alcoholic beverages (vodkas).

Beverages↗

PubMed2000

Determination of sulphur compounds in beer using headspace solid-phase microextraction and gas chromatographic analysis with pulsed flame photometric detection.

A simple and sensitive method for the analysis of volatile and semi-volatile sulphur compounds in beer at trace levels was developed using headspace solid-phase microextraction (SPME) and gas chromatography with pulsed flame photometric detection. Different SPME fibres were tested and a Carboxen-polydimethylsiloxane coated fibre was found to be the most appropriate. The adsorption and desorption conditions were optimised. The effect of ethanol concentration in the sample on the extraction of analytes was examined. A 60 m non-polar capillary column preceded by a 10 m length of a polar column was found to be capable of separating a wide range of C1-C6 sulphur compounds. The pulsed flame photometric detector enabled increased sensitivity to be obtained over previous methods, such as dynamic headspace followed by conventional flame photometric detection or sulphur chemiluminescent detection, with high sulphur selectivity. Two sulphur compounds, 2-methyl-1-butanethiol and 3-methylthiophene, were identified in beer for the first time.

Beer↗

PubMed1999

Analysis of diacetyl in wine using solid-phase microextraction combined with gas chromatography-mass spectrometry.

Analytical difficulties in the rapid and accurate determination of diacetyl (DA), an important flavor compound in wine, at low concentrations have been overcome by the use of solid-phase microextraction (SPME) with deuterated diacetyl-d(6) (d6-DA) as an internal standard followed by gas chromatography-mass spectrometry (GC-MS). The GC-MS analyses showed that the values of the ion response ratio of DA to d6-DA were consistent regardless of the conditions of SPME headspace and were not influenced by the presence of sulfur dioxide in wine. The quantitation value of DA was represented as the concentration of free plus bound with sulfur dioxide forms of DA. The detection limit of DA in wine was as low as 0.01 microg/mL with linearity through to 10 microg/mL.

Diacetyl↗

PubMed2005

Determination of endocrine disruptors in environmental waters using poly(acrylamide-vinylpyridine) monolithic capillary for in-tube solid-phase microextraction coupled to high-performance liquid chromatography with fluorescence detection.

A method for the determination of endocrine disruptors, bisphenol A and 17alpha-ethinylestradiol, in environmental water samples was developed using in-tube solid-phase microextraction followed by liquid chromatography and fluorescence detection. A poly(acrylamide-vinylpyridine) monolithic capillary column was applied as the extraction media in view of its greater phase ratio than open-tubular capillaries and thus higher extraction efficiency. After optimizing the extraction conditions, bisphenol A and 17alpha-ethinylestradiol were extracted directly from water samples in a wide dynamic linear range of 0.5-1000 ng mL(-1), with the detection limits obtained as 0.064 and 0.12 ng mL(-1), respectively. The precision of the method was satisfactory with the intraday and interday RSD values smaller than 7.2%. Environmental water samples of different sources were successfully analyzed with the presented method and the monolithic capillary was proved to be robust and reusable in analyzing real water samples.

Benzhydryl Compounds↗

PubMed2005

A novel fiber coating for solid phase microextraction and its application for the extraction of n-alkane from aqueous sample.

Base on the previous work in laboratory, a novel polyaniline doped with polydimethylsiloxane coating was developed on a stainless steel wire for solid phase microextraction(SPME) by electroplating method. This electroplating method not only has advantages of ease preparation and simple equipments required, but also increases the lifetime of the SPME fiber. The composite fiber (polyaniline/ polydimethylsiloxane(PANI/PDMS)) was evaluated by analyzing n-tridecane, n-tetradecane and n-pentadecane in aqueous sample. The new fiber coating showed comprehensive abilities to extract alkanes compounds. The relative standard deviations were found to be 6.8%-10.33%.

Alkanes↗

PubMed2002

Gas chromatographic determination of 2-hydroxy-4-methoxybenzophenone and octyldimethyl-p-aminobenzoic acid sunscreen agents in swimming pool and bathing waters by solid-phase microextraction.

A method has been developed for the trace determination of two sunscreen constituents (2-hydroxy-4-methoxybenzophenone and octyldimethyl-p-aminobenzoic acid) in water samples, which are commonly used in commercial formulations. The method employs solid-phase microextraction (SPME) and gas chromatography with flame ionization and mass spectrometric detection. The technique was developed with headspace and direct sampling in order to demonstrate the applicability of these SPME extraction modes for the identification of these two UV absorbing compounds in waters. The main parameters affecting the SPME process, such as desorption time, extraction time profile, salt additives, pH, and temperature, were investigated. The poly(dimethylsiloxane) 100-microm and polyacrylate 85-microm fiber coatings were found to be the most efficient for the extraction of these compounds from aqueous matrices. Linear calibration curves in the wide range of 10-500 microg/l were obtained for both compounds yielding typical RSD values of 5-9% for both extraction modes. The recoveries were relatively high, 82-98%, with quantitation limits below 1 microg/l. A comparison between the proposed methods and the conventional multiresidue solid-phase extraction revealed that the proposed technique(s) can be reliably used for sunscreen residue measurement in water samples with satisfactory results.

4-Aminobenzoic Acid↗

PubMed2006

Characterization of livestock odors using steel plates, solid-phase microextraction, and multidimensional gas chromatography-mass spectrometry-olfactometry.

Livestock operations are associated with emissions of odor, gases, and particulate matter (PM). Livestock odor characterization is one of the most challenging analytical tasks. This is because odor-causing gases are often present at very low concentrations in a complex matrix of less important or irrelevant gases. The objective of this project was to develop a set of characteristic reference odors from a swine barn in Iowa and, in the process, identify compounds causing characteristic swine odor. Odor samples were collected using a novel sampling methodology consisting of clean steel plates exposed inside and around the swine barn for < or =1 week. Steel plates were then transported to the laboratory and stored in clean jars. Headspace solid-phase microextraction was used to extract characteristic odorants collected on the plates. All of the analyses were conducted on a gas chromatography-mass spectrometry-olfactometry system where the human nose is used as a detector simultaneously with chemical analysis via mass spectrometry. Multidimensional chromatography was used to isolate and identify chemicals with high-characteristic swine odor. The effects of sampling time, distance from a source, and the presence of PM on the abundance of specific gases, odor intensity, and odor character were tested. Steel plates were effectively able to collect key volatile compounds and odorants. The abundance of specific gases and odor was amplified when plates collected PM. The results of this research indicate that PM is major carrier of odor and several key swine odorants. Three odor panelists were consistent in identifying p-cresol as closely resembling characteristic swine odor, as well as attributing to p-cresol the largest odor response out of the samples. Further research is warranted to determine how the control of PM emissions from swine housing could affect odor emissions.

Animals↗

PubMed2005

Evaluation of solid-phase microextraction as an alternative to the official method for the analysis of organic micro-pollutants in drinking water.

The objective this study was to compare the official EU liquid-liquid extraction (LLE) method with solid-phase microextraction (SPME) for the analysis of compounds migrating from cross-linked polyethylene into water. A medium polarity polydimethylsiloxane/divinylbenzene (PDMS/DVB) 65 microm fibre proved most efficient for the SPME extraction of nine test compounds and the optimum extraction conditions were an immersion time of 30 min with heating to 60 degrees C. The repeatability of the SPME method was variable: RSD values ranged from approximately 4-18% depending on the individual compound, though correlation coefficients were greater than 0.999 in the concentration range 0.5-1000 microg/l. It would also seem that there is some competition amongst different compounds for sites on the fibre and this is a potential drawback of SPME when applied to unknown samples. However, when applied to water samples in contact with polyethylene, SPME proved to be immensely more sensitive and to have a greater extraction range than LLE. These factors coupled with the rapidity and ease of use of SPME mean that it could be developed for use as an alternative to the existing official method or as an alert system in the routine analysis of materials used to transport domestic water.

Chemical Fractionation↗

PubMed2006

Determination of toluene in brain of freely moving mice using solid-phase microextraction technique.

For the purpose of measuring the pharmacokinetics of inhaled toluene in the brain of mice, we developed a method for the direct detection of toluene by gas chromatography/mass spectrometry (GC/MS). The method uses a solid-phase microextraction (SPME) fiber inserted into the mouse' hippocampus (CA1) through a cannula fixed onto the animal. BALB/c mice were exposed to 0, 0.9, 9, 50 and 90 ppm toluene for 30 min. The toluene level detected near the hippocampus by this method after exposure to 0.9 ppm toluene in air showed no significant difference from the level found in the non-exposure control group; however, the toluene level increased significantly after exposure to concentrations of 9, 50 and 90 ppm. These increases were concentration-dependent. In addition, the pharmacokinetics of toluene in the brain of mice exposed to 50 ppm toluene showed that the toluene level decreased rapidly after the exposure, and returned to control levels after 60 min. This study describes the method which has successfully detected toluene levels in the brain of conscious, free-moving mice for the first time.

Animals↗

PubMed2003

Solid-phase microextraction fibre-water distribution constants of more hydrophobic organic compounds and their correlations with octanol-water partition coefficients.

Fibre coating-water distribution constants (Kfw) of more hydrophobic chemicals were determined with six different solid-phase microextraction fibre types (including a polyoctylmethylsiloxane (C8) prototype) by fibre exposure to agitated large-volume water samples lasting several days. The results obtained are comparable with Kfw values obtained under dynamic conditions. Octanol-water partition coefficients (Kow) were measured with the mixture of distributing substances to examine log Kfw-log Kow relationships based on a consistent dataset. Kfw values obtained with liquid polymer fibre coatings correlate reasonably well with the hydrophobicity of the test compounds (with decreasing sensitivity in the following order: 7 microm polydimethylsiloxane (PDMS)>100 microm PDMS>C8>polyacrylate) whereas this is not the case with the PDMS-divinylbenzene (DVB) and Carbowax-DVB fibres, partially porous coatings which provide the highest Kfw values for all substances tested.

Octanols↗

PubMed1999

Solid-phase microextraction of the antifouling Irgarol 1051 and the fungicides dichlofluanid and 4-chloro-3-methylphenol in water samples.

Three pesticides usually added to paint formulations, Irgarol 1051, dichlofluanid and 4-chloro-3-methylphenol, were determined by solid-phase microextraction (SPME) with 85-micron polyacrylate fibers and gas chromatography-mass spectrometry. The parameters affecting the SPME process (the pH, the addition of salt to the sample, and the time and temperature of the absorption step) were optimized. The method developed was applied to the analysis of water samples from Ebro river, marinas and fishing ports. The method enables these compounds to be detected at concentrations between 0.2 and 3.0 micrograms l-1 under full scan conditions and between 0.05 and 0.08 microgram l-1 under SIM mode.

Absorption↗