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Results for “Solid Phase Microextraction”

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PubMed2003

Determination of polycyclic aromatic hydrocarbons in urine of coke oven workers by headspace solid phase microextraction and gas chromatography-mass spectrometry.

Polycyclic aromatic hydrocarbons (PAHs) represent a complex mixture of toxic compounds that are ubiquitous in the environment. We investigated the utility of head space-solid phase microextraction (HS-SPME) to measure the following surrogate PAHs in urine: naphthalene (NAP), phenanthrene (PHE), pyrene (PYR), and benzo(a)pyrene (BAP), representing classes of 2-, 3-, 4- and 5-ring compounds, respectively. We then applied the method to urine from 28 coke oven workers (median levels (microg/l) were: NAP=3.65, PHE=1.51, PYR=0.003, BAP not detected) and 22 controls (median (microg/l) NAP=0.859, PHE=0.062, PYR=0.001, BAP not detected). Urinary levels of NAP, PHE, and PYR were all associated with exposure category (controls, side- and bottom-workers, and top-workers) but not with smoking status. Strong correlations were observed between urinary levels of NAP, PHE, and PYR in coke-oven workers. Our results indicate that unmetabolized 2-, 3- and 4-ring PAHs can be measured in urine by HS-SPME. Such measurements can be used to investigate the uptake and metabolism of complex PAH mixtures in humans.

Adolescent↗

PubMed2002

Gas chromatographic determination of glutaraldehyde in the workplace atmosphere after derivatization with 0-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine on a solid-phase microextraction fibre.

Glutaraldehyde is used primarily in hospital environments for the disinfection of various instruments (e.g., endoscopes). We describe in this paper the measurement of glutaraldehyde in a hospital environment using solid-phase microextraction. The method includes, prior to sampling, the adsorption of O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine on to the fibre (with polydimethylsiloxane-divinylbenzene). The fibre is then exposed to air, after which desorption is performed in the GC injection port. This process results in the formation of a stable derivative of the glutaraldehyde that is suitable for chromatographic purposes and detectable with classical detection methods, such as flame ionisation and electron-capture detection. We demonstrate that the procedure of adsorption, thermal desorption and derivatization is robust and reproducible. We were able to detect concentrations of 60 microg/m3 (10 s sampling) or 6 microg/m3 (120 s sampling) by electron-capture detection, and 80 microg/m3 (120 s sampling) by flame ionisation detection. We compared our method to currently existing methods of glutaraldehyde measurement and highlighted several important advantages of the method.

Air Pollutants, Occupational↗

PubMed2002

Analysis of anatoxin-a in aqueous samples by solid-phase microextraction coupled to high-performance liquid chromatography with fluorescence detection and on-fiber derivatization.

A simple method for analysis of anatoxin-a in aqueous samples was developed using solid-phase microextraction (SPME) and high-performance liquid chromatography (HPLC) with fluorescence detection. Anatoxin-a was derivatized to a fluorogenic agent on the surface of the SPME fiber. In the method an SPME fiber was immersed for 30 min in the aqueous sample. The fluorogenic derivatizing reagent (4-fluoro-7-nitro-2,1,3-benzoxadiazole, 1.0 mg/ml in methanol) was dropped or sprayed onto the fiber containing extracted analytes. The fiber was then heated for 10 min in an empty vial at 70 degrees C in a waterbath to promote derivatization. The derivatives formed on the fiber were desorbed in a SPME-HPLC interface. The interface was filled with methanol-1 mM hydrochloric acid (7:3, v/v) before inserting of the fiber into the interface. For desorption, the fiber was inserted in the interface for 5 min. For anatoxin-a in an aqueous sample, the calibration curve showed linearity in the range of 50-1500 ng/ml and the limit of detection of anatoxin-a was 20 ng/ml. No interferences were found, and the time for analysis was 55 min for one sample.

Bacterial Toxins↗

PubMed2001

Headspace solid-phase microextraction profiling of volatile compounds in urine: application to metabolic investigations.

Volatile compounds contribute substantially to the metabolic pool in man. Their analysis in body fluids is problematic. We investigated headspace solid-phase microextraction (HS-SPME) with Carboxen-polydimethylsiloxane fibres and gas chromatography-mass spectrometry for profiling urinary volatile components. These fibres were more sensitive for very volatile and sulfur compounds than three other phases tested. We detected a wide range of compounds in normal urine at acid and alkaline pH. Profiles presented for five individuals with metabolic disturbances demonstrate abnormal accumulation of sulfur compounds, fatty acids and plasticisers. HS-SPME can complement profiling of non-volatile compounds in metabolic investigations and could be a useful extension of the diagnostic repertoire.

Adult↗

PubMed2001

Solid-phase microextraction (SPME) technique for measurement of generation of fresh cucumber flavor compounds.

Investigations were carried out to determine whether flavor compounds characteristic for fresh cucumbers could be rapidly determined using a solid-phase microextraction (SPME) dynamic headspace sampling method combined with gas chromatography and flame ionization detection. Cucumbers were sampled, during blending, for fresh cucumber flavor compounds (E,Z)-2,6-nonadienal and (E)-2-nonenal. The GC was such that the two target compounds were separated and baseline-resolved. Relative standard deviations for analysis of both (E,Z)-2,6-nonadienal and (E)-2-nonenal using this SPME sampling method were +/-10%. Utility of the analytical method was demonstrated by determining the effect of heat treatments on the ability of cucumbers to produce these flavor impact compounds.

Chromatography, Gas↗

PubMed2003

Characterization of Citrus unshiu (C. unshiu Marcov. forma Miyagawa-wase) blossom aroma by solid-phase microextraction in conjunction with an electronic nose.

The volatile composition of the headspace from Citrus unshiu Marcov. forma Miyagawa-wase blossom was investigated. The volatile constituents were absorbed by a solid-phase microextraction (SPME) fiber and directly transferred to a GC-MS. Volatile compositional changes of C. unshiu blossom prepared via different drying methods (shade, microwave, and freeze-drying methods) were also determined. A total of 96 volatile constituents were confirmed in the headspace from these samples. Monoterpene hydrocarbons were prominent in the headspace volatiles of C. unshiu blossom: fresh, 84.1%; shade-dried, 60.0%; microwave-dried, 88.4%; and freeze-dried, 29.9%. p-Cymene (23.3%) was the most abundant component in the headspace of fresh C. unshiu blossom; gamma-terpinene was the most abundant in shade- and microwave-dried samples (26.8 and 31.2%, respectively) and beta-caryophyllene (10.5%) in freeze-dried sample. By using an electronic nose consisting of six metal oxide sensors, principal component analysis of the volatile compounds showed a clear aroma discrimination of the fresh and all dried blossom samples.

Chromatography, Gas↗

PubMed2003

Solid-phase microextraction for studies on the enantiomeric composition of filbertone in hazelnut oils.

The enantiomeric distribution of filbertone was determined in unroasted and roasted hazelnut oils of different geographical origins by using solid-phase microextraction (SPME) and capillary gas chromatography. An optimization procedure including SPME fiber, extraction time, exposure temperature, and sample volume enabled the best conditions to be selected. Under the optimized conditions, detection limits were in the micrograms per liter level for both enantiomers of filbertone with relative standard deviation values of 7.1 and 4.9% for R-filbertone and S-filbertone, respectively. The proposed approach allowed the rapid determination of the enantiomeric composition of filbertone and demonstrated that its variability is an inherent property of the natural compound. Analysis of two batches of hazelnut oils obtained from either unroasted or roasted hazelnuts showed, in general, significantly higher amounts of filbertone in roasted hazelnut oils.

Chromatography, Gas↗

PubMed2004

Analysis of phthalate contamination in infusion solutions by automated on-line in-tube solid-phase microextraction coupled with high-performance liquid chromatography.

Contamination of infusion solutions with phthalates was analyzed, and its origin was determined. Phthalates were determined by on-line in-tube solid-phase microextraction coupled with high-performance liquid chromatography (in-tube SPME-HPLC) with UV detection. In-tube SPME is an extraction technique for organic compounds in aqueous samples, in which analytes are extracted from the sample directly into an open tubular capillary by repeated draw/eject cycles of sample solution. The infusion solutions were used without any pretreatment, and the phthalates in these solutions were automatically analyzed by the on-line in-tube SPME-HPLC system. The limits of detection of phthalates in the infusion solutions were 1-10 ng/mL. With a few exceptions, the recoveries of phthalates added to the infusion solutions were above 80%. Di-n-butyl phthalate (DBP) was detected at a concentration of 7-60 ng/mL in most infusion solutions in plastic containers but was not detected in those in glass bottles. On the other hand, no other phthalates were detected in infusion solutions in either plastic or glass containers. Large amounts of DBP were detected in the adhesive used to affix the paper labels to the plastic bottles and bags, but not in the plastic containers themselves. Furthermore, DBP was shown to be readily eluted from the adhesive into water and alcohol and easily pass through the plastic. These results indicated that the source of the DBP was the adhesive used to affix the paper labels, and DBP contaminated the infusion solutions by passing through the plastic. The in-tube SPME-HPLC method is simple and rapid and provides a useful tool for the screening and determination of phthalate contamination in infusion solutions.

Adhesives↗

PubMed2002

[Determination of moth-proof agent residues in textiles with headspace solid-phase microextraction and gas chromatography-mass spectrometry].

A procedure is described for the identification and determination of volatile moth-proof pesticide residues, dichlorobenzene and naphthalene, in textile products by headspace solid-phase microextraction (HS-SPME) coupled with GC/MS in selective ion monitoring mode (SIM). Several standard fabrics (ISO 105/F01-1982) are used as sample matrices to reduce the target compound-matrix interaction. Prior to SPME, 0.2 g textile sample is immersed in 3 mL boric acid-citric acid-sodium acid phosphate buffer (pH 2.2) solution with 300 g/L sodium chloride and 5% (volume fraction) methanol for supersonic treatment in water bath(50 +/- 1) degrees C. Then an SPME fiber holder is used manually by passing the needle through the septum of the sample vial, depressing the plunger and lowering a fused silica fiber coated with 100 microns polydimethylsiloxane (PDMS) into the headspace right above the sample solution. Adsorption equilibrium is almost established within 5 minutes with magnetic stirring at (40 +/- 1) degrees C. After sample adsorption, draw SPME fiber into the needle, and withdraw the needle from the sample vial and immediately introduce it into the chromatograph injector, where the adsorbed analytes are thermally desorbed for 3 minutes at 230 degrees C and delivered to a capillary GC column for analysis by mass detector. The method provides data of very good linearity with low coefficients of variation for volatile target compounds like p-dichlorobenzene and naphthalene. For all the fabrics tested, typical limits of detection (LOD) were 1 microgram/kg and average recoveries from fortified sample fabrics were between 83.6%-115.2% and the relative standard deviations of the residues were 8.1%-9.8%.

English Abstract↗

PubMed2006

Gas chromatography-mass spectrometry following microwave distillation and headspace solid-phase microextraction for fast analysis of essential oil in dry traditional Chinese medicine.

In this paper, a novel method based on gas chromatography-mass spectrometry (GC-MS) following microwave distillation-headspace solid-phase microextraction (MD-HS-SPME) was developed for the determination of essential oil in dry traditional Chinese medicine (TCM). TCM is dried before being preserved and used, there is too little water to absorb microwave energy and heat the TCM samples. In the work, carbonyl iron powders (CIP) was added and mixed with the dried TCM sample, which was used as microwave absorption solid medium for dry distillation of the TCM. At the same time, SPME was used for the extraction and concentration of essential oil after MD. The dry rhizomes of Atractylodes lancea DC was used as the model TCM, and used in the study. The MD-HS-SPME parameters including fiber coating, microwave power, irradiation time, and the amount of added CIP, were studied. To demonstrate the method feasibility, the conventional HS-SPME method was also used for the analysis of essential oil in the TCM. Experimental results show that more compounds were isolated and identified by MD-HS-SPME than those by HS-SPME. Compared to conventional HS-SPME, the advantages of the proposed method are: short extraction time and high extraction efficiency. All experimental results show that the proposed method is an alternative tool for fast analysis of essential oils in dry TCMs.

Chemical Fractionation↗

PubMed2001

Detection of perfluorocarbons in blood by headspace solid-phase microextraction combined with gas chromatography/mass spectrometry.

A new method of detection of perfluorocarbon molecules (PFCs) in blood sample has been established. After an extraction and pre-concentration step performed by headspace solid-phase microextraction (HS-SPME), the PFCs are detected by gas chromatography-mass spectrometry (GC/MS) with an ion trap mass spectrometer in MS and MS/MS modes. The influence of different parameters on the SPME process is discussed. The limit of detection and the linearity of the procedure have been determined for two PFCs.

Fluorocarbons↗

PubMed2004

Headspace solid-phase microextraction and capillary gas chromatographic-mass spectrometric determination of rivastigmine in canine plasma samples.

A simple, rapid and sensitive method for determination of rivastigmine in plasma samples was developed using headspace solid-phase microextraction (HS-SPME) and gas chromatography with mass spectrometry (GC-MS). The optimum conditions for the SPME procedure were: headspace extraction on a 65-microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber; 0.5 ml of plasma modified with 1.0 ml of sodium hydroxide-sodium carbonate solution (0.7 M:0.5M); extraction temperature of 100 degrees C, with stirring at 2000 rpm for 30 min. The calibration curve showed linearity in the range from 0.2 to 80 ng/ml with regression coefficient corresponding to 0.9965 and coefficient of the variation of the points of the calibration curve lower than 10%. The quantification limit for rivastigmine in plasma was 0.2 ng/ml. The method was applied to determination of rivastigmine in canine plasma samples from animals after a single oral administration.

Animals↗

PubMed2002

Rapid determination of volatile constituents of Michelia alba flowers by gas chromatography-mass spectrometry with solid-phase microextraction.

The volatile constituents of Michelia alba flowers, including fresh flowers, frozen flowers and withered flowers, were investigated by GC-MS. The volatiles in a simulated natural environment were sampled by solid-phase microextraction (SPME), with a 100 microm polydimethylsiloxane fiber at 25+/-5 degrees C for 4 h. The fibers were desorbed in a GC injection liner at 250 degrees C for 3 min. With headspace SPME-GC-MS analysis, 61 peaks were separated. The main compounds in headspace of fresh Michelia alba flowers included alpha-myrcene, (S)-limonene, (R)-fenchone, linalool, camphor, caryophyllene, germacrene D, etc., a greater number of compounds than for frozen flowers and withered flowers. At the same time, the biomarkers of fresh flowers were compared with the frozen flowers and withered flowers. In this study, headspace SPME-GC-MS afforded a simple and more sensitive sampling method for fresh Michelia alba flowers and other fresh flowers.

Gas Chromatography-Mass Spectrometry↗

PubMed1998

Determination of benzene, toluene, ethylbenzene and xylenes in indoor air at environmental levels using diffusive samplers in combination with headspace solid-phase microextraction and high-resolution gas chromatography-flame ionization detection.

An improved analytical method for passive air sampling is presented based on a combination of commercially available diffusive samplers with headspace solid-phase microextraction and high-resolution gas chromatography with flame ionization detection (HRGC-FID). This procedure is targeted for short-term BTEX (benzene, toluene, ethylbenzene and o-, m- and p-xylenes) determinations at environmental concentrations and can be applied for sampling intervals between 30 min and 24 h. The analytes are adsorbed onto the charcoal pad of a passive sampler and then extracted with carbon disulphide-methanol. After removal of the carbon disulphide by xanthation, the BTEXs are enriched on a Carboxen SPME fiber, thermally desorbed and analysed by HRGC-FID. Detection limits for a sampling interval of 2 h are between 0.4 and 2 micrograms/m3, within-series precision ranges between 6.6 and 12.8%, day-to-day precision is between 11.1 and 15.2%. The results obtained with this procedure are validated by comparison with active sampling. Detection limits and a further reduction of the sampling time are limited by blanks of the chemicals and the diffusive samplers. Procedures to eliminate these blanks are described in detail. Applications such as the determination of BTEXs in indoor air inside buildings, inside a train and a car are presented, indicating the usefulness of the described procedure for short-term measurements of environmental BTEX concentrations. An advantage of passive samplers is the storage stability for at least six months, which is essential for its use in large epidemiological studies.

Adsorption↗

PubMed2001

Field sampling and determination of formaldehyde in indoor air with solid-phase microextraction and on-fiber derivatization.

A new sampling and analysis method for formaldehyde in indoor air was tested in several indoor air surveys. The method was based on the use of solid-phase microextraction (SPME) poly(dimethylsiloxane)/divinylbenzene,65-microm fiber and gas chromatography. Indoor air surveys included grab and time-weighted average (TWA) sampling and were completed at six locations using (a) the SPME method employing on-fiber formaldehyde derivatization with o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride and (b)the conventional National Institute for Occupational Safety and Health (NIOSH) 2451 method. Sampling time for SPME fiber ranged from 10 min for grab sampling to 8 h for TWA sampling. Sampling locations included a residential house, a rental apartment, an office building, and industrial workplaces. The air concentrations measured by SPME ranged from 10 to 380 ppbv and correlated well with those estimated by the NIOSH method. Results also indicated thatin some cases the formaldehyde concentrations measured in residential air could be much higher than those allowed in occupational settings. The SPME method proved to be accurate, fast, sensitive, and cost-efficient in field sampling applications. This research should be of interest to research, industrial, and regulatory agencies as well as to the general public concerned with indoor air quality.

Air Pollution, Indoor↗

PubMed2003

Headspace solid-phase microextraction method for the study of the volatility of selected flavor compounds.

Changes in the volatility of selected flavor compounds in the presence of nonvolatile food matrix components were studied using headspace solid-phase microextraction (HS-SPME) combined with GC-MS quantification. Time-dependent adsorption profiles to the SPME fiber and the partition coefficients between different phases were obtained for several individual volatiles, showing that HS-SPME analysis with a short sampling time can be used to determine the "true" headspace concentration at equilibrium between the headspace and a sample matrix. Equilibrium dialysis followed by HS-SPME/GC-MS was carried out to confirm the ability of HS-SPME extraction for monitoring the free volatile compounds in the presence of proteins. In particular, a short sampling time (1 min) avoided additional extraction of volatiles bound to the protein. Interactions between several selected flavor compounds and nonvolatile food matrix components [beta-lactoglobulin or (+)-catechin] were also studied by means of HS-SPME/GC-MS analysis. The volatility of ethyl hexanoate, heptanone, and hexanal was significantly decreased by the addition of beta-lactoglobulin compared to that of isoamyl acetate. Catechin decreased the volatility of ethyl hexanoate and hexanal by 10-20% and increased that of 2-heptanone by approximately 15%. This study indicates that HS-SPME can be a useful tool for the study of the interactions between volatile compounds and nonvolatile matrix components provided the kinetic and thermodynamic behavior of the volatiles in relation to the fiber chosen for the studies is carefully considered.

Adsorption↗

PubMed2003

Analysis of aldehydes in beer using solid-phase microextraction with on-fiber derivatization and gas chromatography/mass spectrometry.

A new, fast, sensitive, and solventless extraction technique was developed in order to analyze beer carbonyl compounds. The method was based on solid-phase microextraction with on-fiber derivatization. A derivatization agent, O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBOA), was absorbed onto a divinyl benzene/poly(dimethylsiloxane) 65-microm fiber and exposed to the headspace of a vial with a beer sample. Carbonyl compounds selectively reacted with PFBOA, and the oximes formed were desorbed into a gas chromatograph injection port and quantified by mass spectrometry. This method provided very high reproducibility and linearity. When it was used for the analysis of aged beers, nine aldehydes were detected: 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, pentanal, hexanal, furfural, methional, phenylacetaldehyde, and (E)-2-nonenal.

Aldehydes↗

PubMed2005

Monitoring of five sulfonamide antibacterial residues in milk by in-tube solid-phase microextraction coupled to high-performance liquid chromatography.

A simple, rapid, and sensitive method for the quantitative monitoring of five sulfonamide antibacterial residues in milk was developed by coupling in-tube solid-phase microextraction (SPME) to high-performance liquid chromatography with an ultraviolet detector. A poly(methacrylic acid-ethylene glycol dimethacrylate) monolithic capillary column was selected as the extraction medium for this on-line technique. To obtain optimum extraction efficiency, several parameters relating to in-tube SPME were investigated. By simple extraction with ethanol, dilution with phosphate buffer solution, and centrifugation, the sample solution then could be directly injected into the device for extraction. The calculated detection limits for sulfadiazine, sulfamethazine, sulfamethoxazole, sulfamonomethoxine sodium, and sulfacetamide sodium were 2.0, 2.8, 1.7, 2.5, and 22 ng/mL, respectively. The method was linear over the range of 20-5000 ng/mL (100-5000 ng/mL for sulfacetamide sodium) with a correlation coefficient R (2) value >0.9980. Excellent method reproducibility was found by intra- and interbatch precisions, yielding the relative standard deviations of <10.0 and <9.94%, respectively. The proposed method was proved to be robust in monitoring sulfadiazine, sulfamethazine, sulfamethoxazole, sulfamonomethoxine sodium, and sulfacetamide sodium residues in milk.

Animals↗