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PubMed2004

Application of solid-phase microextraction to the analysis of volatile compounds in virgin olive oils.

Solid-phase microextraction was used as a technique for headspace sampling of extra virgin olive oil and virgin olive oil samples with different off-flavours. A 100 microm coated polydimethylsiloxane fiber was used to extract volatile aldehydes, the sampling temperature was 45 degrees C and the fiber has been exposed to the headspace for 15 min. Nonanal and 2-decenal were present in all the olive oils with extraction off-flavours but were not in extra virgin olive oil sample.

Aldehydes↗

PubMed2005

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

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.

Gas Chromatography-Mass Spectrometry↗

PubMed2005

Solid phase microextraction gas chromatographic analysis of organophosphorus pesticides in biological samples.

Headspace-solid phase microextraction (HS-SPME) was studied and optimised for the determination of four common organophosphorus pesticides (OPPs) in biological samples. Various parameters controlling SPME were studied: choice of SPME fiber, type and content of salt added, preheating and extraction time, desorption time, extraction temperature. Capillary gas chromatographic analysis with nitrogen phosphorus detection (GC-NPD) facilitates sensitive and selective detection of the OPPs: malathion, parathion, methyl parathion and diazinon. Fenitrothion was used as the internal standard. The method was applied to the determination of the pesticides in human biological specimens: whole blood, blood plasma, urine, cerebrospinal fluid, liver and kidney. Limits of detection ranged from 2 to 55 ng/ml depending on pesticide and type of specimen. The developed methodology overcomes limitations and obstacles of conventional methods such as the use of organic solvents, the formation of emulsions and the tedious-cumbersome procedures. The proposed protocol is seen as an attractive alternative to be used in routine toxicological analysis.

Body Fluids↗

PubMed2006

Measurement of the free concentration of octylphenol in biological samples with negligible depletion-solid phase microextraction (nd-SPME): analysis of matrix effects.

A negligible depletion-solid phase microextraction (nd-SPME) method is presented to measure free concentrations of octylphenol in biological samples. Potential confounding factors, such as matrix effects, are studied as well. Fouling of the fibre appears to occur, but it does not seem to reduce or enhance the measured uptake of octylphenol. In the setup applied here, without any agitation, it has also been found that there is a large effect of protein presence on the kinetics of octylphenol uptake. In addition, an apparent affinity constant of octylphenol for bovine serum albumin was determined.

Culture Media↗

PubMed2000

Headspace solid-phase microextraction procedures for gas chromatographic analysis of biological fluids and materials.

Solid-phase microextraction (SPME) is a new solventless sample preparation technique that is finding wide usage. This review provides updated information on headspace SPME with gas chromatographic separation for the extraction and measurement of volatile and semivolatile analytes in biological fluids and materials. Firstly the background to the technique is given in terms of apparatus, fibres used, extraction conditions and derivatisation procedures. Then the different matrices, urine, blood, faeces, breast milk, hair, breath and saliva are considered separately. For each, methods appropriate for the analysis of drugs and metabolites, solvents and chemicals, anaesthetics, pesticides, organometallics and endogenous compounds are reviewed and the main experimental conditions outlined with specific examples. Then finally, the future potential of SPME for the analysis of biological samples in terms of the development of new devices and fibre chemistries and its coupling with high-performance liquid chromatography is discussed.

Body Fluids↗

PubMed2001

On-site field sampling and analysis of fragrance from living lavender (Lavandula angustifolia L.) flowers by solid-phase microextraction coupled to gas chromatography and ion-trap mass spectrometry.

Solid-phase microextraction coupled to gas chromatography and mass spectrometry has been applied as a simple alternative method for the analysis of essential oil directly from lavender intact flowering spikes and genuine oils. All recognised major oil constituents were detected by this procedure, with results comparable to those given by a conventional method (organic solvent extraction). Distinctive chromatographic profiles were found for various species.

Gas Chromatography-Mass Spectrometry↗

PubMed2002

Comparison of different coatings in solid-phase microextraction for the determination of organochlorine pesticides in ground water.

A solid-phase microextraction (SPME) procedure using three commercialised fibers (Carbowax-divinylbenzene, Carboxen-polydimethylsiloxane and divinylbenzene-Carboxen-polydimethylsiloxane) is presented for the determination of a selected group of organochlorine compounds in water samples. The extraction performances of these compounds were compared using fibers with two and three coatings. The optimal experimental procedures for the adsorption and desorption of pesticides were determined. The limits of detection with the divinylbenzene-Carboxen-polydimethylsiloxane fiber at levels below ng l(-1) were similar or lower than values presented in the literature for several of these compounds using polydimethylsiloxane fiber. The advantages of using this fiber, such as no salt addition, are discussed. Finally, the optimised procedures were applied successfully for the determination of these compounds in polluted ground water samples.

Hydrocarbons, Chlorinated↗

PubMed2003

Monolithic silica column for in-tube solid-phase microextraction coupled to high-performance liquid chromatography.

In-tube solid-phase microextraction (SPME) has successfully been coupled to capillary LC, and further an automated in-tube SPME system has been developed using a commercially available HPLC auto-sampler. However, an open tubular capillary column with a thick film of polymer (stationary phase) is unfavorable because the ratio of the surface area of coating layer contacted with sample solution to the volume of the capillary column is insufficient for mass transfer. A highly efficient SPME column is. therefore, required. We introduced a C18-bonded monolithic capillary column that was used for in-tube SPME. The column consisted of continuous porous silica having a double-pore structure. Both the through-pore and the meso-pore were optimized for in-tube SPME, and the optimized capillary column was connected to an HPLC injection valve for characterization. The results demonstrated that the pre-concentration efficiency is excellent compared with the conventional in-tube SPME. The novel method for both introduction and concentration of the samples was effective. satisfactory and suitable for use in the SPME medium.

Chromatography, High Pressure Liquid↗

PubMed2003

Determination of organochlorine pesticides in water using microwave assisted headspace solid-phase microextraction and gas chromatography.

A coupled technique, microwave-assisted headspace solid-phase microextraction (MA-HS-SPME), was investigated for one-step in situ sample pretreatment for organochlorine pesticides (OCPs) prior to gas chromatographic determination. The OCPs, aldrin, o,p'-DDE, p,p'-DDE, o,p'-DDT, p,p'-DDT, dieldrin, alpha-endosulfan, beta-endosulfan, endosulfan sulfate, endrin, delta-HCH, gamma-HCH, heptachlor, heptachlor epoxide, methoxychlor and trifluralin were collected by the proposed method and analyzed by gas chromatography with electron-capture detection (GC-ECD). To perform the MA-HS-SPME, six types of SPME fibers were examined and compared. The parameters affecting the efficiency in MA-HS-SPME process such as sampling time and temperature, microwave irradiation power, desorption temperature and time were studied to obtain the optimal conditions. The method was developed using spiked water samples such as field water and with 0.05% humic acid in a concentration range of 0.05-2.5 microg/l except endosulfan sulfate in 0.25-2.5 microg/l. The detection was linear over the studied concentration range with r2>0.9978. The detection limits varied from 0.002 to 0.070 microg/l based on S/N=3 and the relative standard deviations for repeatability were <15%. A certified reference sample of OCPs in aqueous solution was analyzed by the proposed method and compared with the conventional liquid-liquid extraction procedure. These results are in good agreement. The results indicate that the proposed method provides a very simple, fast, and solvent-free procedure to achieve sample pretreatment prior to the trace-level screening determination of organochloride pesticides by gas chromatography.

Chromatography, Gas↗

PubMed2000

Evaluation of solid-phase microextraction for the study of protein binding in human plasma samples.

Solid-phase microextraction (SPME) in combination with capillary gas chromatography and a nitrogen-phosphorous detector is used to study protein binding in human plasma samples. Local anesthetics of the amide-type (ropivacaine, bupivacaine, mepivacaine, prilocaine, and lidocaine) are used as model compounds in this evaluation. Carbowax/divinylbenzene (CW/DVB), polyacrylate, and polydimethylsiloxane fibers are tested. Sampling on CW/DVB fibers give the highest recovery in plasma samples compared with other fibers. Ultrafiltrate spiked with each of the substances is used for the construction of calibration curves. The protein binding is investigated at four different total concentrations from 0.5 to 15.0 microM. The degree of protein binding increases when the solute concentration decreases. Protein binding of the five solutes is investigated at four pH levels (6.4, 7.4, 8.4, and 9.4). It is found that protein binding increased with increasing pH. The influence of temperature variation (from 32 degrees C to 40 degrees C) on protein binding is also investigated. The protein binding decreases when the temperature increases. The methodology is validated and good correlation and precision are obtained. Back-calculated quality control samples give accuracy within 20% of theoretical values for all five substances. This study shows that SPME as a sample-preparation method gives the same protein binding for the studied local anesthetics as that achieved using earlier presented methods.

Anesthetics, Local↗

PubMed2002

Solid-phase microextraction as a sample preparation strategy for the analysis of seleno amino acids by gas chromatography-inductively coupled plasma mass spectrometry.

Solid-phase microextraction (SPME) is used as a sample preparation strategy for gas chromatographic (GC) analysis of the seleno amino acids, selenomethionine (SeMet), selenoethionine (SeEt) and selenocystine (SeCys). Acylation of the amino group and esterification of the carboxylic group in these compounds was performed with isobutylchloroformate to increase volatility. The amino acid derivatives were then extracted by silica fibers with polydimethylsiloxane (PDMS) coatings prepared by the sol-gel process. Investigations of extraction time, acid and salt addition, and polymer length (for the sol-gel process) were conducted with the goal of procedural optimization. Initial characterizations were conducted using gas chromatography with flame ionization detection (GC-FID). Inductively coupled plasma mass spectrometric detection was employed for final selenium detection. Sub-ppb detection limits were obtained for all analytes although relative standard deviations were higher than those typically obtained in solid-phase microextraction.

Amino Acids↗

PubMed2006

Comparison of two solid-phase microextraction methods for the quantitative analysis of VOCs in indoor air.

Competitive adsorption on adsorptive solid-phase microextraction (SPME) fibres implies careful determination of operating conditions for reliable quantitative analysis of VOCs in indoor air. With this objective, two analytical approaches, involving non-equilibrium and equilibrium extraction, were compared. The average detection limit obtained for GC-MS analysis of nine VOCs by the equilibrium method is 0.2 microg m(-3), compared with 1.9 microg m(-3) with the non-equilibrium method. The effect of the relative humidity of the air on the calibration plots was studied, and shown to affect acetone adsorption only. Hence, the concentrations that can be accurately determined are up to 9 micromol m(-3). The methods were then applied to indoor air containing different concentrations of VOCs. The non-equilibrium method, involving short extraction time, can be used for detection of pollution peaks whereas equilibrium extraction is preferable for measurement of sub-microg m(-3) ground concentration levels.

Adsorption↗

PubMed2006

Optimization of the solid-phase microextraction method in the determination of Ixodes ricinus (L.) volatiles.

For the first time, headspace solid-phase microextraction coupled with GC-MS analysis was used to study volatile compounds emitted by the tick Ixodes ricinus (L.). Variables such as the type of SPME fibre, equilibration time and extraction time have been evaluated with the mixture of four selected standards, a so-called artificial tick (acetophenone, racemic 4-heptanolide, methyl 2-methoxybenzoate and methyl 3-chloro-4-methoxybenzoate). Optimized conditions were obtained by the use of polydimethylsiloxan 100 microm fibre at 30 min equilibration and 15 min extraction time. The method proved to have a good linearity (r2 >0.98) at a concentration range from 0.5 ng (1 ng for methyl 3-chloro-4-methoxybenzoate) to 25 ng. LODs for a compound ranged between 0.19 and 1 ng, RSD (%) ranged from 13.76 to 25.08. The determination of 1.99 ng of methyl 3-chloro-4-methoxybenzoate emitted by five engorged females proved the usefulness of the developed method to identify and quantify the volatile compounds emitted by I. ricinus ticks.

Animals↗

PubMed2002

Analysis of antifouling biocides Irgarol 1051 and Sea Nine 211 in environmental water samples using solid-phase microextraction and gas chromatography.

This study develops a method for the analysis of biocides Irgarol 1051 and Sea Nine 211 in environmental water samples, using solid-phase microextraction (SPME). Their determination was carried out using gas chromatography with flame thermionic (FTD), electron-capture (ECD) and mass spectrometric detection. The main parameters affecting the SPME process such as adsorption-time profile, salt additives and memory effect were studied for five polymeric coatings commercially available for solid-phase microextraction: poly(dimethylsiloxane) (100 and 30 microm), polyacrylate, poly(dimethylsiloxane)-divinylbenzene (PDMS-DVB 65 microm) and Carbowax-divinylbenzene (65 microm). The method was developed using spiked natural waters such as tap, river, sea and lake water in a concentration range of 0.5-50 microg/l. All the tested fiber coatings have been evaluated with regard to sensitivity, linear range, precision and limits of detection. Typical RSD values (triplicate analysis) in the range of 3-10% were obtained depending on the fiber coating and the compound investigated. The recoveries of biocides were in relatively high levels 60-118% and the calibration curves were reproducible and linear (R2>0.990) for both analytes. The SPME partition coefficients (Kf) of both compounds were also calculated experimentally in the proposed conditions for all fibers using direct sampling. Finally the influence of organic matter such as humic acids on extraction efficiency was studied, affecting mostly Sea Nine 211 uptake by the fiber. Optimum analytical SPME performance was achieved using the PDMS-DVB 65 microm fiber coating in ECD and FTD systems for Sea Nine 211 and Irgarol 1051, respectively.

Chromatography, Gas↗

PubMed1999

[A novel solid phase coating of solid-phase microextraction prepared with sol-gel technology and its applications].

In this paper, the recent development and applications of solid-phase microextraction (SPME) are summed up. A sol-gel method was applied for the preparation of solid phase coating in SPME. The exposed outer surface was coated with hydroxy-terminated poly (dimethylsiloxane). The characteristics of this solid phase were evaluated. The coating possesses higher thermal stability, and shorter extraction and desorption time. This solid phase appears to have strong affinity to both polar compounds and non-polar compounds. The scanning electron micrograph of the coated surface presents a porous structure. In the analyses of the environmental samples, ideal results were also obtained.

Animals↗

PubMed2006

Sample pretreatment method for the determination of polychlorinated biphenyls in bird livers using ultrasonic extraction followed by headspace solid-phase microextraction and gas chromatography-mass spectrometry.

A simple and reliable sample methodology based on simultaneous ultrasonic extraction, sulfuric acid clean-up and headspace solid-phase microextraction (SPME)-gas chromatography-mass spectrometry has been developed as an advantageous analytical tool for the determination of seven polychlorinated biphenyl congeners in bird livers at low levels. The influence of several parameters on the efficiency of the proposed method was systematically investigated. The clean-up efficiency of sulfuric acid treatment was tested and compared with those of column chromatography (Flosiril, silica gel and alumina) and solid-phase extraction (SPE) (Supelclean ENVI-Carb cartridge) procedures. The use of sulfuric acid in the clean-up step prior to headspace solid-phase microextraction analysis allows the removal of interfering matrix compounds present in the liver extracts that would otherwise cause severe ionization suppression of the polychlorinated biphenyls (PCBs) during the ionization process. The optimized method had good linearity (R2>0.99) over the range studied (5-500 ng/g wet weight) and showed satisfactory level of precision, with RSD values lower than 10.6%. The obtained relative recoveries ranged between 63 and 94%. The limits of detection (0.06-0.63 ng/g wet weight) were low enough to check for harmful levels of polychlorinated biphenyls in biological samples, and were well below most of the restrictive limits established by European Union regulations. The method was found to be reliable under the operational conditions proposed and was applied successfully to the analysis of individual polychlorinated biphenyls in liver tissues. The results obtained from five bird species from Greece revealed the presence of the target compounds in all samples analyzed, at levels ranging between 0.54 and 39.45 ng/g wet weight.

Animals↗

PubMed2006

Determination of frequently detected herbicides in water by solid-phase microextraction and gas chromatography coupled to ion-trap tandem mass spectrometry.

A method based on solid-phase microextraction (SPME) coupled with GC and ion trap tandem mass spectrometry has been developed for the analysis of nine herbicides and degradation products, among the most frequently found in natural water. A polydimethylsiloxane-divinylbenzene (PDMS-DVB)-coated fiber was selected to extract the analytes directly from the samples over the 0.01-1 microg L(-1) concentration range. Optimization of manual and automated SPME was performed on the basis of desorbed amounts, via various factorial experiment designs. Of the two modes, the automated one was found to be the most efficient. Memory effect was avoided owing to the 10-min fiber desorption time. Limits of detection reached down to below 0.01 microg L(-1) and repeatability ranged from 3 to 15% in natural water. A validation study was conducted involving the quantitation of the target compounds in Seine water with SPME/GC-MS-MS external calibration.

Chromatography, Gas↗

PubMed2006

Identification of volatile components in Angelica species using supercritical-CO2 fluid extraction and solid phase microextraction coupled to gas chromatography-mass spectrometry.

As a part of our search for environmentally friendly solvents to extract the active components of medicinal plants, two sampling techniques, supercritical fluid extraction (SFE) using CO(2) and solid-phase microextraction (SPME) were compared for their efficacy in the analysis of volatiles rhizome components emitted from the medicinal herbs Angelica gigas NAKAI (Korean danggui), Angelica sinensis (Chinese danggui), and Angelica acutiloba (Japanese danggui). A total of 54 compounds released from all of these varieties of Angelica rhizomes were separated and identified by gas chromatography-mass spectrometry (GC-MS). The composition of supercritical extracts from these plants was very different from the solid-phase microextraction products. More compounds were detected by SPME-GC-MS (41) than by SFE-GC-MS (17). The results of these analyses suggest that SFE may be useful for detecting the main components, decursinol angelate and decursin in Korean danggui, and butylidene dihydro-phthalide in both Chinese and Japanese danggui, whereas the results for SPME did not. The SFE method required specialized instrumentation, required little time to prepare the sample, and had a small sample size and no organic solvent. In sum, these results suggest that SFE is useful for extracting the volatile main components of danggui cultivars. Its simplicity, low cost and speed may allow SPME to increase the recovery of volatile components in general without disturbing the main components of the plant.

Angelica↗