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Results for “Solid Phase Microextraction”

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PubMed2002

Determination of liposome/water partition coefficients of organic acids and bases by solid-phase microextraction.

The extraction of two methylated anilines and three chlorinated phenols by solid-phase microextraction (SPME) fibers coated with polyacrylate was investigated as a function of pH. Only the neutral species of the acids and bases partitioned into the polymer. Extraction kinetics were accelerated for the hydrophobic phenols at pH values around their acidity constant. This is presumably due to a reconstitution of the neutral species in the unstirred aqueous layer adjacent to the polymer surface by the charged species through the fast acid-base equilibrium. Although the charged species is not taken up into the polymer, liposome/water distribution ratios could be measured up to a pH value, where 99% of the compounds were present as charged species. The partition coefficients of the neutral and charged species were extrapolated from the pH profiles of the liposome/water distribution ratios. The resulting values were slightly lower than those measured with equilibrium dialysis. The discrepancies are discussed with respect to differences in the experimental conditions and the possibility of matrix effects during SPME measurements.

Journal Article↗

PubMed2003

Solid-phase microextraction to monitor the sonochemical degradation of polycyclic aromatic hydrocarbons in water.

Solid-phase microextraction (SPME) coupled with GC-MS has been used to monitor the degradation of polycyclic aromatic hydrocarbons (PAHs) by ultrasound treatment. Immersion SPME sampling enabled the fast and solventless extraction of target contaminants at the low microg l(-1) concentration level. The developed protocol was found to be linear in the concentration range from 0.1 to 50 microg l(-1) for most target analytes, with the limits of detection ranging between 0.01 and 0.70 microg l(-1) and the relative standard deviations between 4.31 and 27%. The developed SPME protocol was used to follow concentration profiles of aqueous solutions containing 16 PAHs, which were subject to low frequency ultrasonic irradiation. At the conditions employed in this study (80 kHz of ultrasound frequency, 130 W l(-1) of applied electric power density, 30 microg l(-1) of initial concentration for each of the 16 PAHs), sonochemical treatment was found capable of destroying the lower molecular weight PAHs (naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene) within 120-180 min of irradiation. The higher molecular weight PAHs were more recalcitrant to ultrasound treatment.

Environmental Monitoring↗

PubMed2005

Development of a solid phase microextraction (SPME) method for the sampling of VOC traces in indoor air.

Solid-phase microextraction (SPME) was studied for the measurement of volatile organic compounds (VOCs) in indoor air. An adsorptive PDMS/Carboxen fibre was used and an analytical methodology was developed in order to overcome competitive adsorption. Kinetics and adsorption isotherms were investigated for different sample volumes and model compounds. In order to evaluate competitive adsorption on the fibre, these compounds were studied alone and in mixture. From the results obtained, the operating conditions allowing co-adsorption of the target compounds were determined: the air sample is enclosed in a 250 mL glass bulb where the SPME fibre is exposed until adsorption equilibrium. This procedure was combined with GC/MS analysis for the identification and quantification of VOCs in indoor air. The performances were determined by using a standard gas containing 10 VOCs representative of indoor environments (acetaldehyde, acetone, BTX, alpha-pinene, trichloroethylene, alkanes). The detection limits were determined in single ion monitoring mode and for a signal to noise ratio of 3. Except acetaldehyde (6 microg m(-3)), they are all below 0.5 microg m(-3). Calibration curves are linear up to 10 micromol m(-3) for all the compounds with good correlation coefficients (above 0.99). The reproducibility ranges from 6 to 12% according to the compound. The methodology was then applied to the comparison of the VOCs content in classrooms of two different schools.

Adsorption↗

PubMed2003

Use of solid phase microextraction (SPME) for profiling fungal volatile metabolites.

AIMS: The influence of isolation methods: solid phase microextraction (SPME) with different fibres and simultaneous distillation extraction (SDE) on the profile of isolated fungal volatile metabolites was investigated. METHODS AND RESULTS: Four SPME fibre types: Polydimethylsiloxane, Polyacrylate, Carboxen/PDMS and Carboxen/Divinylbenzene/PDMS were evaluated in terms of their efficiency in extracting volatile metabolites emitted by Penicillium roqueforti grown on wheat kernel medium. All fibres showed varied efficiency and selectivity in extracting volatile compounds. Sesquiterpene hydrocarbons were the predominant fraction of volatile compounds isolated by all fibres, and ranged from 55.4 to 93.7% of all volatiles depending on the type of fibre used. Alcohols and ketones ranged from 2.7 to 20.5%, esters from 1.2 to 12.8%, and monoterpene hydrocarbons from 1.2 to 5.4%. Profile of volatile compounds obtained by SDE differed from SPME and the oxygenated sesquiterpenes formed the predominant fraction of volatiles isolated using SDE. SIGNIFICANCE AND IMPACT OF THE STUDY: The data in this study show that analysed profile of volatile compounds emitted by fungi is highly dependent on the extraction method.

Fungi↗

PubMed2002

Solid phase microextraction: measurement of volatile organic compounds (VOCs) in Dhaka City air pollution.

A solid phase microextraction (SPME) technique was applied for the sampling of volatile organic compounds (VOCs) in ambient air polluted by two stroke autorickshaw engines and automobile exhausts in Dhaka city, Bangladesh. Analysis was carried out by capillary gas chromatography (GC) and GC-mass spectrometry (MS). The methodology was tested by insitu sampling of an aromatic hydrocarbon mixture gas standard with a precision of +/-5% and an average accuracy of 1-20%. The accuracy for total VOCs concentration measurement was about 7%. VOC's in ambient air were collected by exposing the SPME fiber at four locations in Dhaka city. The chromatograms showed signature similar to that of unburned gasoline (petrol) and weathered diesel containing more than 200 organic compounds; some of these compounds were positively identified. These are normal hydrocarbons pentane (n-C5H2) through nonacosane (n-C29H60), aromatic hydrocarbons: benzene, toluene, ethylbenzene, n-propylbenzene, n-butylbenzene, 1,3,5-trimethylbenzene, xylenes, and 1-isocyanato-3-methoxybenzene. Two samples collected near an autorickshaw station contained 783000 and 1479000 microg/m3 of VOCs. In particular, the concentration of toluene was 50-100 times higher than the threshold limiting value of 2000 microg/m3. Two other samples collected on street median showed 135000 microg/m3 and 180000 microg/m3 of total VOCs. The method detection limit of the technique for most semi-volatile organic compounds was 1 microg/m3.

Air Pollutants↗

PubMed2000

Solid-phase microextraction method for the quantitative analysis of styrene in water.

A headspace solid-phase microextraction (HS-SPME) method is developed for the determination of styrene in drinking water. Gas chromatography (GC)-mass spectrometry is utilized for qualitative analysis. A manual SPME holder with 85-microm polyacrylate coating is used to extract the styrene from water, which is determined to have good linearity (correlation coefficient r = 0.9999 for 1.00-100.00 microg/L range), a relative standard deviation of 1.9%, and a detection limit of 0.30 microg/L. This method is compared with a classical headspace GC method.

Gas Chromatography-Mass Spectrometry↗

PubMedDate not supplied

Analysis of Rhioxma Curcumae Aeruginosae volatiles by solid-phase microextraction with gas chromatography-mass spectrometry.

In this paper, a headspace solid-phase microextraction (HS-SPME) method was applied to analyse the volatile compounds in a traditional Chinese medicine (TCM), Rhioxma Curcumae Aeruginosae. SPME parameters such as fibers, extraction temperature, extraction time and desorption time were investigated. Thirty-five volatile compounds were separated and identified. Relative standard deviations (RSDs) were less than 8.4%, showing that the method has a good reproducibility. The volatile constituents were also analyzed by steam distillation (SD) and thirty-seven compounds were identified. The similar results obtained by the two methods showed that SPME is a good alternative for the analysis of volatile constituents in Rhioxma Curcumae Aeruginosae samples and it is a relatively simple, rapid and solvent-free method.

Camphor↗

PubMed2002

Analysis of n-alkanes at sub microgram per liter level after direct solid phase microextraction from aqueous samples.

This work describes the application of the previously presented solid phase microextraction (SPME) fiber in direct mode for sampling of C10-C20 n-alkanes from aqueous solution. The fiber has simple composition and is constructed from activated charcoal:PVC suspension in tetrahydrofuran. When the composition of the fiber was optimized that the optimum composition was 90:10 (activated charcoal:PVC) for direct mode, whereas it was 75:25 for sampling from the headspace of aqueous samples. This fiber is completely stable in contact with water. The extraction efficiency is improved in the presence of 0.1 M NaCl. The value is between 17.8-38.5% for the first extraction, which better than the efficiency of similar commercial fibers. After seven extractions, all analytes are removed from the aqueous samples nearly 100%. Single fiber repeatability and fiber-to-fiber reproducibility are good and both are less than 13% for all studied alkanes. Finally, direct mode SPME was used in the determination of n-alkanes in the range of sub microg L(-1) without any additional preconcentration procedure. Gas chromatography along with flame ionization detection were used for separation and detection of the studied analytes.

Alkanes↗

PubMed2005

[Analysis of volatile components from the flowers of Chrysanthemum morifolium by GC-MS with solid-phase microextraction].

OBJECTIVE: To study a method for extraction and analysis of volatile components from Chrysanthemum morifolium 'gonghuangjv' cv. nov (CM GHJ) and C. morifolium 'gongbaijv' cv. nov (CM GBJ) by solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS). METHOD: The volatile components were extracted in different temperature, different balance period and different extraction fiber using head space solid-phase microextraction (HS-SPME), and were identified by CGC-MS. The variety in integral area of each component was observed in different conditions and its relative content was determined by normalization of area. RESULT: The better condition of SPME for C. morifolium was that the sample was extracted using 100 microm polydimethylsiloxane (PDMS) extraction fiber after it had been balanced for 6 hours at 75 degrees C. 53 components from CM GHJ and CM GBJ were identified, and there were 35 same components in CM GHJ and CM GBJ. CONCLUSION: HS-SPME-GC-MS is convenient, rapid and reliable for analysis of volatile components in C. morifolium.

Chrysanthemum↗

PubMed1995

Detection of amphetamines in urine using head space-solid phase microextraction and chemical ionization selected ion monitoring.

An accurate, simple and rapid method for qualitative and quantitative analysis of amphetamine and methamphetamine in urine was developed using head space-solid phase microextraction and gas chromatography-mass spectrometry/chemical ionization selected iron monitoring. A vial containing a urine sample potassium carbonate and pentadeuterated methamphetamine which was used as an internal standard was heated at 80 degrees C for 20 min. The needle of a solid phase microextraction device was passed through the septum, and the extraction fiber in the needle was exposed for 5 min in the head space of the vial. The needle was removed from the vial and inserted into the injection port of gas chromatograph or gas chromatograph/mass spectrometer. The compounds adsorbed on the fiber were detached by exposing the fiber in the injection port, and analyzed. The proposed method was more than 20 times more sensitive than the conventional head space method.

Amphetamine↗

PubMed2006

[Analysis of volatile constituents from leaves of plants by gas chromatography/mass spectrometry with solid-phase microextraction].

A method for analyzing volatile constituents from plant leaves with gas chromatography/mass spectrometry (GC/MS) coupled with solid-phase microextraction (SPME) was developed. The volatile compounds from the plant leaves inside a sealed flask maintained at 45 degrees C in a water bath were efficiently extracted with Polyacrylate (85 microm) SPME fibers prior to perform GC/MS analysis. The GC/MS analysis indicated that the volatile compounds from the plant leaves which is easy to be damaged by Tetraychus vienneis include relative large amounts of cis-3-hexenyl ester acetic acid, cis-3-hexenyl ester butanoic acid and alpha-famesene. These compounds were preliminarily confirmed to be accountable for attracting Tetraychus vienneis. This finding may lead to identify biological species for preventing and treating Tetraychus vienneis.

Clinical Laboratory Techniques↗

PubMed2006

[Determination of chlorophenols in drinking water by headspace solid phase microextraction and gas chromatography].

OBJECTIVE: To study the method for determination of chlorophenols in drinking water by headspace solid phase microextraction and gas chromatography. METHODS: Chlorophenols in water samples was extracted using optimized SPME technology, separated by HP-5 chromatigraphic column and the concentration of chlorophenols was determined by electron capture detector (ECD). RESULTS: The detection limit of MCP, DCP, TCP, PCP were 60.0 microg/L, 2.64 microg/L, 0.15 microg/L and 0.84 microg/L. The correlation coefficient(r) were 0.999, 0.997, 0.997, 0.995. When adding standard material of MCP, DCP, TCP, PCP at low, middle, high concentrations, the recovery rates were 95.3% - 107%, 93.6% - 102%, 92.4% - 102%, 91.5% -99.1% and the RSD (n = 6) were 1.0% - 8.1%,1.6% - 6.6%, 2.9% - 8.6%, 2.0% - 8.2%. CONCLUSION: The method was simple, sensitive and without solvent, which was an ideal method for determination of chlorophenols in drinking water.

Chlorophenols↗

PubMed2006

Analysis of semi-volatile organic compounds in aqueous samples by microwave-assisted headspace solid-phase microextraction coupled with gas chromatography-electron capture detection.

The pretreatment technique of microwave-assisted headspace solid-phase microextraction (MA-HS-SPME) has been developed and studied for the extraction of semi-volatile organic compounds (SVOCs) in aqueous samples prior to chromatographic analysis. The optimum conditions for obtaining extraction efficiency, such as the extraction time, extraction temperature, addition of salts, and the ratio of sample to headspace volume parameters were investigated. Experimental results indicated that the proposed MA-HS-SPME technique attained the best extraction efficiency under the optimized conditions, i.e., irradiation of extraction solution (20mL aqueous sample in 40mL headspace vial with no addition of salt) under 30W microwave power for 30min at 70 degrees C. The detection was linear at 1-250ng/L with correlation coefficient exceeding 0.997. The detection limits obtained were between 0.2-10.7ng/L, repeatability range from 2 to 15%. Real water samples collected from known sites in southern Taiwan were analyzed using the optimized conditions.

Chlorobenzenes↗

PubMed2005

Sol-gel-coated oligomers as novel stationary phases for solid-phase microextraction.

Amphiphilic and hydrophilic oligomers were synthesized and coated on fused silica capillaries using a sol-gel technique. Sol-gel-coated capillaries were evaluated for the solid-phase microextraction and preconcentration of a wide variety of non-polar and polar analytes. Both types of coatings were stable under high temperature (up to 280 degrees C). The extraction efficiency of the sol-gel coatings was evaluated for the extraction of both non-polar and polar analytes, including organochlorine pesticides, triazine herbicides, estrogens and alkylphenols (APs) and bisphenol-A (BPA). Compared with commercially available solid-phase microextraction (SPME) adsorbents such as poly(dimethylsiloxane)divenylbenzene and polyacrylate, the new materials showed comparable selectivity and sensitivity towards both non-polar and polar analytes. The new coatings gave good linearity and detection limits. For example with triazines, a detection limit of <0.005 microl l(-1), precision from 5.0 to 11.0% (n = 6) and linearity of the calibration plots (0.5 to 50 microl l(-1)) were obtained. The sol-gel coated SPME capillaries were used for the determination of triazine herbicides in reservoir water samples collected in Singapore.

Estrogens↗

PubMed2006

Active sampling followed by solid-phase microextraction for the determination of pyrethroids in indoor air.

A method based on solid-phase enrichment followed by headspace (HS)-solid-phase microextraction (SPME) is optimized to determine pyrethroids in air. By active sampling, pyrethroids present in air are retained in 25 mg of activated florisil and then transferred from the solid sorbent to an SPME fiber in the HS mode. A small volume of solvent is added to the adsorbent to favor this process. The selection of the adsorbent, as well as the optimization of certain parameters affecting the SPME, is performed using an experimental design strategy. Linearity is studied by external calibration in a wide range of concentrations using gas chromatography coupled to three different detection systems: electron capture detection, micro-electron capture detection, and mass spectrometry. An analysis of variance with a lack-of-fit test is run to validate the calibration data. Breakthrough of the adsorbent was studied sampling from 0.5 to 10 m(3) air, demonstrating that 1 m(3) air could be sampled without losses of pyrethroids. Quantitative recoveries are obtained at three concentration levels, with adequate repeatability. Limits of detection of the method are estimated at the sub-ng/m(3) level in most cases, well below the regulatory limits. Finally, several real indoor samples are collected and analyzed by the proposed method. Identification and quantitation of all target analytes present in the room air are possible.

Air Pollutants↗

PubMed2001

Biotransformation of (R)-(+)- and (S)-(-)-limonene by fungi and the use of solid phase microextraction for screening.

The biotransformation of (R)-(-)- and (S)-(-)-limonene by fungi was investigated. More than 60 fungal cultures were screened for their ability to bioconvert the substrate, using solid phase microextraction as the monitoring technique. After screening, the best fungal strains were selected for further study and were grown as sporulated surface cultures in conical flasks and as submerged liquid cultures. It was found that (+)- and (-)-limonene were converted by Penicillium digitatum to alpha-terpineol (main metabolite), cis- and trans-p-menth-2-en-1-ol, neodihydrocarveol and limonene oxide (minor metabolites) using liquid cultures. The bioconversion of (R)-(-)- and (S)-(-)-limonene by Corwespora cassiicola yielded (1S,2S,4R)- and (1R,2R,4S)-limonene-1,2-diol respectively. The bioconversions by liquid cultures were also monitored by solid phase microextraction as a function of time. The optimum conversion of limonene to alpha-terpineol by Penicillium digitatum was obtained after 8 hours (yield up to 100%). Since an important pH-decrease was noticed in some liquid broths, the stability of limonene under acidic conditions was investigated. No acid catalysed conversion products were recovered after 8 days from control flasks at pH 3.5 containing limonene.

Ascomycota↗

PubMed2006

Determination of fluoroquinolones in eggs using in-tube solid-phase microextraction coupled to high-performance liquid chromatography.

A simple, rapid, and sensitive method using in-tube solid-phase microextraction (in-tube SPME) based on poly(methacrylic acid-ethylene glycol dimethacrylate) (MAA-EGDMA) monolith coupled to HPLC with fluorescence and UV detection was developed for the determination of five fluoroquinolones (FQs). Ofloxacin (OFL), norfloxacin (NOR), ciprofloxacin (CIP), enrofloxacin (ENRO), and sarafloxacin (SARA) can be enriched and determined in the spiked eggs and albumins. CIP/ENRO in eggs and albumins of ENRO-treated hens were also studied using the proposed method. Only homogenization, dilution, and centrifugation were required before the sample was supplied to the in-tube microextraction, and no organic solvents were consumed in the procedures. Under the optimized extraction conditions, good extraction efficiency for the five FQs was obtained with no matrix interference in the process of extraction and the subsequent chromatographic separation. The detection limits (S/N=3) were found to be 0.1-2.6 ng g(-1) and 0.2-2.4 ng g(-1) in whole egg and egg albumin, respectively. Good linearity could be achieved over the range 2-500 ng mL(-1) for the five FQs with regression coefficients above 0.9995 in both whole egg and albumin. The reproducibility of the method was evaluated at three concentration levels, with the resulting relative standard deviations (RSDs) less than 7%. The method was successfully applied to the analysis of ENRO and its primary metabolite CIP in the eggs and albumins of ENRO-treated hens.

Albumins↗

PubMed2004

Speciation analysis of mercury by solid-phase microextraction and multicapillary gas chromatography hyphenated to inductively coupled plasma-time-of-flight-mass spectrometry.

This paper reports the development of an analytical approach for speciation analysis of mercury at ultra-trace levels on the basis of solid-phase microextraction and multicapillary gas chromatography hyphenated to inductively coupled plasma-time-of-flight mass spectrometry. Headspace solid-phase microextraction with a carboxen/polydimethylsyloxane fiber is used for extraction/preconcentration of mercury species after derivatization with sodium tetraethylborate and subsequent volatilization. Isothermal separation of methylmercury (MeHg), inorganic mercury (Hg2+) and propylmercury (PrHg) used as internal standard is achieved within a chromatographic run below 45 s without the introduction of spectral skew. Method detection limits (3 x standard deviation criteria) calculated for 10 successive injections of the analytical reagent blank are 0.027 pg g(-1) (as metal) for MeHg and 0.27 pg g(-1) for Hg2+. The repeatability (R.S.D., %) is 3.3% for MeHg and 3.8% for Hg2+ for 10 successive injections of a standard mixture of 10pg. The method accuracy for MeHg and total mercury is validated through the analysis of marine and estuarine sediment reference materials. A comparison of the sediment data with those obtained by a purge-and-trap injection (PTI) method is also addressed. The analytical procedure is illustrated with some results for the ultra-trace level analysis of ice from Antarctica for which the accuracy is assessed by spike recovery experiments.

Gas Chromatography-Mass Spectrometry↗