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PubMed2005

Coupling of SPME with MCC/UV-IMS as a tool for rapid on-site detection of groundwater and surface water contamination.

The combination of headspace solid phase microextraction (HS-SPME) [1] with fast chromatographic pre-separation by means of multi-capillary columns (MCC) coupled to an ion mobility spectrometer equipped with a 10.6 eV photoionisation source was applied to rapid on-site monitoring of ground and surface water contaminations. Under field conditions, water contaminants were directly detectable down to the upper microg/L range. The potential of the developed method is illustrated by measurements of BTEX, naphthalene, chlorinated alkenes and chlorinated benzenes in water. Practical results from investigations of contaminated groundwater at a former gasworks site and groundwater from the site of a metal processing plant, focusing on the key substances benzene, naphthalene and tetrachloroethene, demonstrate the feasibility of the system for field studies.

Chromatography, Gas↗

PubMed2006

Further research on the photo-SPME of triclosan.

In this study the photoinduced degradation of triclosan has been investigated by photo-solid-phase microextraction (photo-SPME). In photo-SPME, photodegradation is carried out on the SPME fibre containing the target compound. Triclosan was extracted from aqueous solutions by use of polydimethylsiloxane SPME fibres and these were subsequently exposed to UV irradiation (power 8 W, wavelength 254 nm) for different times (from 2 to 60 min). The photodegradation kinetics of triclosan were investigated, the photoproducts generated were tentatively identified, and the photochemical behaviour of these products was studied by use of this on-fibre approach followed by gas chromatographic-mass spectrometric analysis. Eight photoproducts were tentatively identified, including chlorinated phenols, chlorohydroxydiphenyl ethers, 2,8-dichlorodibenzo-p-dioxin, and a possible dichlorodibenzodioxin isomer or dichlorohydroxydibenzofuran. The main photodegradation mechanisms were postulated and photodegradation pathways proposed. The effect of pH on triclosan degradation and on triclosan-to-dioxin conversion was also investigated. Triclosan degradation occurred, and generation of 2,8-dichlorodibenzo-p-dioxin was confirmed, throughout the pH range studied (from 3 to 9).

Anti-Infective Agents, Local↗

PubMed2006

Optimization of an analytical methodology for the determination of alkyl- and methoxy-phenolic compounds by HS-SPME in biomass smoke.

A sampling and analysis method for the determination of 21 phenolic compounds in smoke samples from biomass combustion has been developed. The smoke is used to make smoked foods, following an artisanal procedure used in some parts of the Canary Islands. The sampling system consists of a Bravo H air sampler, two impingers, each one containing an aqueous solution of sodium hydroxide 0.1 mol L(-1), followed by a silica gel trap. The variables optimized to reach the best sampling conditions were volume of absorbent solution and sampling flow. Under the optimum conditions, 100 mL of absorbent solution of NaOH 0.10 mol L(-1) and 2 L min(-1) for the sampling flow, sampling efficiencies are higher than 80%. Analysis of phenolic compounds was carried out by headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). Five different fiber coatings were employed in this study. By means of a central composite design, extraction time, salt concentration, and pH of the solution were optimized: 65-microm carbowax-divinylbenzene, extraction time 90 min, concentration in NaCl of 35% (m/v), and pH 2 yielded the highest response. Detection limits of phenol and their alkyl derivatives, guaiacol and eugenol, are between 1.13 and 4.60 ng mL(-1). 3-Methoxyphenol, 2,6-dimethoxyphenol, and vanillin have detection limits considerably higher. Good linearity (R2 > or = 0.98) was observed for all calibration curves in the established ranges. The reproducibility of the method (RSD, relative standard deviation) was found to oscillate between 7 and 18% (generally close or lower than 10%).

Biomass↗

PubMed2006

SPME in environmental analysis.

Recent advances in the use of solid-phase microextraction (SPME) in environmental analysis, including fiber coatings, derivatization techniques, and in-tube SPME, are reviewed in this article. Several calibration methods for SPME, including traditional calibration methods, the equilibrium extraction method, the exhaustive extraction method, and several diffusion-based calibration methods, are presented. Recent developed SPME devices for on-site sampling and several applications of SPME in environmental analysis are also introduced.

Journal Article↗

PubMed2006

Full automation of solid-phase microextraction/on-fiber derivatization for simultaneous determination of endocrine-disrupting chemicals and steroid hormones by gas chromatography-mass spectrometry.

A fully automated method using direct immersion solid-phase microextraction (DI-SPME) and headspace on-fiber silylation for simultaneous determinations of exogenous endocrine-disrupting chemicals (EDCs) and endogenous steroid hormones in environmental aqueous and biological samples by gas chromatography-mass spectrometry (GC-MS) was developed and compared to a previously reported manual method. Three EDCs and five endocrine steroid hormones were selected to evaluate this method. The extraction and derivatization time, ion strength, pH, incubation temperature, sample volume, and extraction solvent were optimized. Satisfactory results in pure water were obtained in terms of linearity of calibration curve (R2=0.9932-1.0000), dynamic range (3 orders of magnitude), precision (4-9% RSD), as well as LOD (0.001-0.124 microg L(-1)) and LOQ (0.004-0.413 microg L(-1)), respectively. These results were similar to those obtained using a manual method, and moreover, the precision was improved. This new automated method has been applied to the determinations of target compounds in real samples used in our previous study on a manual SPME method. Exogenous octylphenol (OP), technical grade nonylphenol (t-NP), and diethylstilbestrol (DES) were at 0.13, 5.03, and 0.02 microg L(-1) in river water and 3.76, 13.25, and 0.10 microg L(-1) in fish serum, respectively. Natural steroid hormones estrone (E1), 17beta-estradiol (E2), and testosterone (T) were at 0.19, 0.11, and 6.22 microg L(-1) in river water; and in female fish serum E1, E2, and pregnenolone (PREG) were at 1.37, 1.95, and 6.25 microg L(-1), respectively. These results were confirmed by the manual method. The developed fully automated SPME and on-fiber silylation procedures showed satisfactory applications in environmental analysis and the performances show improved precision and a reduced analysis time compared to the manual method.

Animals↗

PubMed2007

Recently developed GC/MS and LC/MS methods for determining NSAIDs in water samples.

Pharmaceuticals have become major targets in environmental chemistry due to their presence in aquatic environments (following incomplete removal in wastewater treatment or point-source contaminations), threat to drinking water sources and concern about their possible effects to wildlife and humans. Recently several methods have been developed for the determination of drugs and their metabolites in the lower nanogram per litre range, most of them using solid-phase extraction (SPE) or solid-phase microextraction (SPME), derivatisation and finally gas chromatography mass spectrometry (GC-MS), gas chromatography tandem mass spectrometry (GC-MS/MS) and liquid chromatography electrospray tandem mass spectrometry (LC-ES/MS/MS). Due to the elevated polarity of non-steroidal anti-inflamatory drugs (NSAIDs), analytical techniques based on either liquid chromatography coupled to mass spectrometry (LC-MS) and gas chromatography coupled to mass spectrometry (GC-MS) after a previous derivatisation step are essential. The most advanced aspects of current GC-MS, GC-MS/MS and LC-MS/MS methodologies for NSAID analysis are presented.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2000

Application of solid phase micro extraction for the rapid analysis of chlorinated organics in breast milk.

The method presented here allows the monitoring of persistent organochlorine compounds in breast milk using the solid phase microextraction technique (SPME) and gas chromatography with electron capture detection (GC-ECD). It describes the determination of hexachlorobenzene (HCB), alpha-, beta-, and gamma-hexachlorocyclohexane (HCH), dichlorodiphenyltrichloroethane (DDT) and its derivatives, and some important congeners of the polychlorinated biphenyls (PCB). Also included are more polar substances such as tri-, tetra- and penta-chlorophenols, which can be analyzed simultaneously with the afore-mentioned less polar compounds without the need of a derivatization for the determination of the phenolic compounds. The reproducibility of the results is very good down to the lower microg/L-region. The method is very fast and of low cost compared to the classic extraction and determination procedures.

Chromatography, Gas↗

PubMed2001

Comparison of extraction techniques for gas chromatographic determination of volatile carbonyl compounds in alcohols.

Two extraction procedures, i.e. conventional liquid-liquid extraction (LLE) and liquid solid-phase microextraction (SPME) for extraction of the oximes formed after derivatization of carbonyl compounds with o-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine (PFBHA) in alcoholic solutions have been compared. The limit of detection for LLE followed by GC-ECD determination of C1-C6 was in the range of 0.23-3.3 microg/L, whereas for liquid SPME 0.005-0.33 microg/L. Both methods elaborated can be applied to the determination of carbonyl compounds present in spirits and alcoholic beverages.

Alcoholic Beverages↗

PubMed2001

Development of a SPME-GC-ECD methodology for selected pesticides in must and wine samples.

A method for the determination of some pesticide residues in must and wine samples was developed using solid-phase microextraction (SPME) and gas chromatography-electron capture detection (GC/ECD). The procedure only needs dilution as sample pre-treatment and is therefore simple, fast and solvent-free. Eight fungicides (vinclozolin, procymidone, iprodione, penconazole, fenarimol, folpet, nuarimol and hexaconazole), one insecticide (chlorpyriphos) and two acaricides (bromopropylate and tetradifon) can be quantified. Good linearity was observed for all the compounds in the range 5-100 microg/L. The reproducibility of the measurements was found acceptable (with RSD's below 20%). Detection limits of 11 microg/L, on average, are sufficiently below the proposed maximum residue limits (MRL's) for these compounds in wine. The analytical method was applied to the determination of these compounds in Portuguese must and wine samples from the Demarcated Region of Alentejo, where any residues could be detected.

Chromatography, Gas↗

PubMed2001

Sensitive method for determination of methyl tert-butyl ether (MTBE) in water by use of headspace-SPME/GC-MS.

A simple and rapid method for the determination of methyl tert-butyl ether (MTBE) in water by headspace-solid-phase microextraction (headspace-SPME) at sub-microg/L concentrations is described. On using a cooled SPME fiber coated with a 75-microm layer of poly(dimethylsiloxane)/carboxene and heating the sample to 35 degrees C, about 4 times more MTBE is extracted compared to SPME extraction with the fiber placed in the water sample. Stable analytical conditions with a detection limit of 10 ng/L are achieved. By use of a sample volume of 4 mL in a 10 mL vial, a sodium chloride content of 10% (w/w), and an extraction time of 30 min, the total time of an analytical cycle was optimized to 39 min. Precise linearity of R2>0.9991 and R2>0.9916 in the calibration range of 20-5000 ng/L and 20-100 ng/L, both in addition to blanks, respectively, and relative standard deviations of 10% (100 ng/L, long-term) and 11% (20 ng/L, short-term) are presented. The recovery is well within the accepted limits of 83-118% at a concentration of 100 ng/L and even close thereto at trace levels of 20 ng/L (96-125%). The data presented for a concentration of 100 ng/L are examined by statistical methods and show results for the T test at the 95% confidence level. Due to the large concentration range covered, the method is well suited for the monitoring of MTBE in the aquatic environment.

Calibration↗

PubMed1996

Preconcentration and determination of Sn- and Pb-organic species in environmental samples by SPME and GC-AED.

A new sample preparation and preconcentration technique - solid phase microextraction (SPME) - is reported for the application of several tinorganic compounds and tetrabutyllead in aqueous samples. The solvent-free procedure is rapid in comparison with liquid-liquid extraction or SFE but also sensitive. Analytical variables of the extraction such as adsorption and desorption time, stirring rate and temperature has been investigated. The determination has been performed by GC coupled with atomic emission detection (AED). After optimization of the conditions of SPME a calibration was realized on the basis of a multicomponent standard solution, prepared by ethylation of organotin salts directly in the sample using sodium tetraethylborate (NaBEt(4)) without prior separation of the analytes from the matrix. The method permits preconcentration. Values of about 10 can be reached. A detection limit of 0.09 pg Sn and 0.08 pg Pb can be achieved under optimized conditions. The proposed procedure has been successfully applied to the analysis of organotin compounds in various slurry samples.

Journal Article↗

PubMed1998

Rapid SPME/LC/MS/MS analysis of N-methylcarbamate pesticides in water.

Solid-phase microextraction combined with fast short-column liquid chromatography/electrospray ionization tandem mass spectrometry (SPME/LC/MS/MS) was used for isolating and analyzing nine N-methylcarbamate pesticides from water samples. Several SPME parameters, such as polarity of fibers, extraction time, and effect of ionic strength, were investigated and their impact on the SPME/LC/MS/MS technique was studied. The method was shown to be sensitive with detection limits between 0.3 and 1.9 microg/L and reproducible with precision between 4.5 and 12.7% RSD. The versatility of the method was exhibited by its excellent linearity in the concentration range of 2-2,000 microg/L in drinking water. A comparison of the SPME/LC/MS/MS method with LC/MS/MS methods utilizing traditional sample preparation techniques shows that the former offers similar performance in terms of precision and linearity, but is clearly easier to use and faster to perform.

Adsorption↗

PubMed1999

Aerobic degradation of a hydrocarbon mixture in natural uncontaminated potting soil by indigenous microorganisms at 20 degrees C and 6 degrees C.

A hydrocarbon mixture containing p-xylene, naphthalene, Br-naphthalene and straight aliphatic hydrocarbons (C14 to C17) was aerobically degraded without lag phase by a natural uncontaminated potting soil at 20 degrees C and 6 degrees C. Starting concentrations were approximately 46 ppm for the aromatic and 13 ppm for the aliphatic compounds. All aliphatic hydrocarbons were degraded within 5 days at 20 degrees C, to levels below detection (ppb levels) but only down to 10% of initial concentration at 6 degrees C. Naphthalene was degraded within 12 days at 20 degrees C and unaffected at 6 degrees C. At 20 degrees C p-xylene was degraded within 20 days, but no degradation occurred at 6 degrees C. Br-naphthalene was only removed down to 30% of initial concentration at 20 degrees C, with no significant effect at 6 degrees C. The biodegradation was monitored with head space solid-phase microextraction and gas chromatography-mass spectrometry.

Aerobiosis↗

PubMed2000

Biological degradation of selected hydrocarbons in an old PAH/creosote contaminated soil from a gas work site.

An old PAH/creosote contaminated soil (total approximately 300 microg PAH/g soil) from a former gas work site in Stockholm, Sweden, has been treated at 20 degrees C with the addition of various nutrients and inoculated with bacteria (isolated from the soil) to enhance the degradation of selected hydrocarbons. Microcosm studies showed that the soil consisted of two contaminant fractions: one available, easily degraded fraction and a strongly sorbed, recalcitrant one. The bioavailable fraction, monitored by headspace solid phase microextraction, contained aromatics with up to three rings, and these were degraded within 20 days down to non-detectable levels (ng PAH/g soil) by both the indigenous bacteria and the externally inoculated samples. The nutrient additives were: a minimal medium (Bushnell-Haas), nitrate, nitrite, potting soil (Anglamark, Sweden), sterile water and aeration with Bushnell-Haas medium. After 30 days treatment most of the sorbed fractions were still present in the soil. Stirring or mechanical mixing of the soil slurries had the greatest effect on degradation, indicating that the substances were too strongly sorbed for the microorganisms. When stirring the choice of nutrient seemed less important. For the non-stirred samples the addition of nitrate with the bacterial inoculum showed the best degradation, compared to the other non-stirred samples. At the end of the experiments, accumulations of metabolites/degradation products, such as 9H-fluorenone, 4-hydroxy-9H-fluorenone, 9,10-phenanthrenedione and 4H-cyclopenta[def]phenanthrenone were detected. The metabolite 4-hydroxy-9H-fluorenone increased by several orders of magnitude during the biological treatments. Microbial activity in the soil was measured by oxygen consumption and carbon dioxide production.

Biodegradation, Environmental↗

PubMed2005

Production of the long-chain alcohols octanol, decanol, and dodecanol by Escherichia coli.

As a follow-up to earlier studies on the emission of long-chain alcohols from broth cultures of Gram-negative enteric bacteria, E. coli was examined for the production of 1-octanol, 1-decanol, and 1-dodecanol. Ten strains of E. coli cultured in tryptic soy broth were assayed for volatile metabolites using solid-phase microextraction. Long-chain alcohols were produced by all strains with 1-decanol predominating with production ranging from 23.6 ng mL(-1) to 148 ng mL(-1). The production of long-chain alcohols followed the onset of the exponential growth phase of the broth culture. Doubling the concentration of glucose (5 g L(-1)) in the broth had no effect on the concentration of long-chain alcohols produced. Addition of octanoic, decanoic, or dodecanoic acids (as K(+) salts) to the broth (100 mg L(-1)) markedly increased the production of the corresponding alcohols by E. coli, ranging from a 13-fold increase for decanol to a 51-fold increase for dodecanol. However, decanol remained the predominant alcohol detected in all assays. These neutral volatile alcohols may have application as vapor-phase indicators for certain classes of bacteria, particularly, Gram-negative enteric bacteria.

Chromatography, Gas↗

PubMed2004

The moss Physcomitrella patens releases a tetracyclic diterpene.

The presence of the tetracyclic diterpene 16alpha-hydroxykaurane (16alpha-hydroxy-ent-kaurane, C20H34O, CAS 5524-17-4) was detected in sterile cell cultures of the moss Physcomitrella patens (Hedw.) B.S.G. using gas chromatography and mass spectrometry. 16alpha-hydroxykaurane was found to be a major lipid compound in P. patens, with an estimated intracellular concentration of up to 0.84 mmol/l and an extracellular concentration of up to 9.3 micromol/l. The overall content of 16alpha-hydroxykaurane (in milligrams) produced per culture reached 0.37-fold that of chlorophyll a+b. In agar cultures with low air exchange, 16alpha-hydroxykaurane forms needle-like crystals on tissue and on the inner surface of the culture vessels, indicating that it is being released into the atmosphere. Solid phase microextraction confirmed the air-bound release of 16alpha-hydroxykaurane. To our knowledge this is the first report on the release of a plant-derived tetracyclic diterpene into the air.

Bryopsida↗

PubMed2000

Comparison between blood and urinary toluene as biomarkers of exposure to toluene.

OBJECTIVES: To compare blood toluene (TOL-B) and urinary toluene (TOL-U) as biomarkers of occupational exposure to toluene, and to set a suitable procedure for collection and handling of specimens. METHOD: An assay based on headspace solid-phase microextraction (SPME) was used both for the determination of toluene urine/air partition coefficient (lambdaurine/air) and for the biological monitoring of exposure to toluene in 31 workers (group A) and in 116 non-occupationally exposed subjects (group B). Environmental toluene (TOL-A) was sampled during the work shift (group A) or during the 24 h before specimen collection (group B). Blood and urine specimens were collected at the end of the shift (group A) or in the morning (group B) and toluene was measured. RESULTS: Toluene lambdaurine/air was 3.3 +/- 0.9. Based on the specimen/air partition coefficient, it was calculated that the vial in which the sample is collected had to be filled up to 85% of its volume with urine and 50% with blood in order to limit the loss of toluene in the air above the specimen to less than 5%. Environmental and biological monitoring of workers showed that the median personal exposure to toluene (TOL-A) during the work-shift was 80 mg/m3, the corresponding TOL-B was 82 microg/l and TOL-U was 13 microg/l. Personal exposure to toluene in environmentally exposed subjects was 0.05 mg/m3, TOL-B was 0.36 microg/l and TOL-U was 0.20 microg/l. A significant correlation (P < 0.05) was observed between TOL-B or TOL-U and TOL-A (Pearson's r = 0.782 and 0.754) in workers, but not in controls. A significant correlation was found between TOL-U and TOL-B both in workers and in controls (r = 0.845 and 0.681). CONCLUSION: The comparative evaluation of TOL-B and TOL-U showed that they can be considered to be equivalent biomarkers as regards their capacity to distinguish workers and controls and to correlate with exposure. However, considering that TOL-U does not require an invasive specimen collection, it appears to be a more convenient tool for the biological monitoring of exposure to toluene.

Adult↗

PubMed2004

Diet-mediated inter-colonial aggression in the formosan subterranean termite Coptotermes formosanus.

In most social insects, intercolonial and interspecific aggression are expressions of territoriality. In termites, cuticular hydrocarbons (CHCs) have been extensively studied for their role in nestmate recognition and aggressive discrimination of nonnest-mates. More recently, molecular genetic techniques have made it possible to determine relatedness between colonies and to investigate the influence of genetics on aggression. In the Formosan subterranean termite, Coptotermes formosanus, however, the role of CHCs and genetic relatedness in inter-colony aggression has been ambiguous, suggesting the involvement of additional factors in nest-mate recognition. In this study we assess the range of aggression in this termite species and characterize the influence of genetic relatedness, CHC profiles and diet on aggression levels. We collected four colonies of C. formosanus, feeding either on bald cypress or birch, from three locations in Louisiana. Inter-colony aggression ranged from low to high. Differences in CHC profiles, as well as genetic distances between colonies determined by using microsatellite DNA markers, showed no significant correlation with aggression. However, termite diet (host tree) played a significant role in determining the level of aggression. Thus, two distantly related colonies, each feeding on different diets, showed high aggression that significantly diminished if they were fed on the same wood in the laboratory (spruce). Using headspace solid phase microextraction, we found three compounds from workers fed on birch that were absent in workers fed on spruce. Such diet-derived chemicals may be involved in the complex determination of nest-mate recognition in C. formosanus.

Aggression↗