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PubMed1999

Fishing for a drug: solid-phase microextraction for the assay of clozapine in human plasma.

Solid-phase microextraction (SPME) was investigated as a sample preparation method for assaying the neuroleptic drug clozapine in human plasma. A mixture of human plasma, water, loxapine (as internal standard) and aqueous NaOH was extracted with a 100-micron polydimethylsiloxane (PDMS) fiber (Supelco). Desorption of the fiber was performed in the injection port of a gas chromatograph at 260 degrees C (HP 5890; 30 m x 0.53 mm I.D., 1 micron film capillary; nitrogen-phosphorous selective detection). Fibers were used repeatedly in up to about 75 analyses. The recovery was found to be 3% for clozapine from plasma after 30 min of extraction. However, in spite of the low recovery, the analyte was well separated and the calibration was linear between 100 and 1000 ng/ml. The within-day and between-day precision was consistently about 8 to 15% at concentrations of 200 ng/ml to 1000 ng/ml. No interfering drug was found. The limit of detection was 30 ng/ml. The sample volume was 250 microliters. The influence of the concentration of proteins, triglycerides and salt, i.e., changes in the matrix on the peak areas and peak-area ratios was studied. The method is not impaired by physiological changes in the composition of the matrix. Good agreement was found with a liquid-liquid extraction-gas-liquid chromatography (LLE-GLC) standard method and an on-line column-switching high-performance liquid chromatography (HPLC) method for patients' samples and spiked samples, respectively. It is concluded that the method can be used in the therapeutic drug monitoring of clozapine because the therapeutic window of clozapine is from 350 to 600 ng/ml.

Chromatography, Gas↗
PubMed1998

Solid-phase microextraction (SPME) of drugs and poisons from biological samples.

Solid-phase microextraction (SPME), a new solvent-free sample preparation technique, was invented by C. Arthur and J. Pawliszyn in 1990. This method mainly was applied for the extraction of volatile and semi-volatile organic pollutants in water samples. However, since 1995, SPME has been developed to various biological samples, such as whole blood, plasma, urine, hair and breath, in order to extract drugs and poisons in forensic field. The main advantages of SPME are: high sensitivity, solventless, small sample volume, simplicity and rapidity. We have reviewed the papers published in recent years about SPME in biological samples, and sorted out main experimental conditions, such as fibers, matrixes, the extraction approaches and time, as well as the acceleration method. We would expect SPME technique to have a promising future for toxicological analysis in forensic practice.

Body Fluids↗
PubMed2002

Simultaneous detection of amphetamine-like drugs with headspace solid-phase microextraction and gas chromatography-mass spectrometry.

A headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS) procedure for the simultaneous detection of methylen-dioxyamphetamine (MDA), methylen-dioxymethamphetamine (MDMA), methylen-dioxyethamphetamine (MDE) and N-methyl-1-(1,3-benzodioxol-5-yl)-2-butanamine (MBDB) in hair has been developed. This method is suitable for the separation of primary and secondary amines, is reproducible, is not time consuming, requires small quantities of sample and does not require any derivatization. It provides sufficient sensitivity and specificity, with limits of detection (LOD) and limits of quantitation (LOQ) for each substance of <0.7 and 1.90 ng/mg, respectively. Intra- and inter-day precision were within 2 and 10%, respectively. This method is suitable for routine clinical, epidemiological and forensic purposes and can be used for the preliminary screening of many other substances (amphetamine, methamphetamine, ketamine, ephedrine, nicotine, phencyclidine, methadone) in hair and other biological matrices such as saliva, urine and blood. We also describe the first application of this HS-SPME-GC-MS procedure to the analysis of hair and saliva samples from young people attending a disco in the Rome area. All positive hair samples were confirmed by the gas chromatography-mass-mass (GC-MS(2)) technique in positive chemical ionization (PCI) mode. Some examples of the use of the method in detecting different drugs are reported.

Adolescent↗
PubMed1998

Solid-phase microextraction of monocyclic aromatic amines from biological fluids.

A solid-phase microextraction (SPME) protocol was developed for the quantitative analysis of monocyclic aromatic amines from biological fluids. The headspace SPME sampling technique was optimized for extraction and concentration of five target analytes (aniline, o-toluidine, 2-chloroaniline, 2,6-dimethylaniline, 2,4,6-trimethylaniline) from urine, blood, and milk. The temperature, pH, and ionic strength of the matrix sample were modified to allow maximum adsorption of the analytes onto the SPME fiber. This method is rapid yet sensitive and can be completed in 15 min on a 5-mL sample. SPME/GC/MS analysis yielded good reproducibility (RSD > 11%) for each analyte from urine, blood, and milk. Method detection limits for the various biological fluids were determined and ranged from 0.40 ppb for 2,4,6-trimethylaniline in urine to 7.7 ppb for aniline in blood. This SPME sampling protocol can be applied to the biomonitoring of monocyclic aromatic amines from occupational, environmental, and medical exposure.

Calibration↗
PubMed2003

Identification of volatile compounds in soybean at various developmental stages using solid phase microextraction.

Soybean (Glycine max) seed volatiles were analyzed using a solid phase microextraction (SPME) method combined with gas chromatography-mass spectrometry (GC-MS). Thirty volatile compounds already reported for soybean were recovered, and an additional 19 compounds not previously reported were identified or tentatively identified. The SPME method was utilized to compare the volatile profile of soybean seed at three distinct stages of development. Most of the newly reported compounds in soybean seed were aldehydes and ketones. During early periods of development at maturity stage R6, several volatiles were present at relatively high concentrations, including 3-hexanone, (E)-2-hexenal, 1-hexanol, and 3-octanone. At maturity stage R7 and R8, decreased amounts of 3-hexanone, (E)-2-hexenal, 1-hexanol, and 3-octanone were observed. At maturity stage R8 hexanal, (E)-2-heptenal, (E)-2-octenal, ethanol, 1-hexanol, and 1-octen-3-ol were detected at relatively high concentrations. SPME offers the ability to differentiate between the three soybean developmental stages that yield both fundamental and practical information.

Aldehydes↗
PubMed2003

Simultaneous determination of ochratoxin A and cyclopiazonic, mycophenolic, and tenuazonic acids in cornflakes by solid-phase microextraction coupled to high-performance liquid chromatography.

A solid-phase microextraction (SPME) method, coupled to liquid chromatography with diode array UV detection (LC-UV/DAD), for the simultaneous determination of cyclopiazonic acid, mycophenolic acid, tenuazonic acid, and ochratoxin A is described. Chromatographic separation was achieved on a propylamino-bonded silica gel stationary phase using acetonitrile/methanol/ammonium acetate buffer mixture (78:2:20, v/v/v) as mobile phase. SPME adsorption and desorption conditions were optimized using a silica fiber coated with a 60 microm thick polydimethylsiloxane/divinylbenzene film. Estimated limits of detection and limits of quantitation ranged from 3 to 12 ng/mL and from 7 to 29 ng/mL, respectively. The method has been applied to cornflake samples. Samples were subjected to a preliminary short sonication in MeOH/2% KHCO(3) (70:30, v/v); the mixture was evaporated to near dryness and reconstituted in 1.5 mL of 5 mM phosphate buffer (pH 3) for SPME followed by LC-UV/DAD. The overall procedure had recoveries (evaluated on samples spiked at 200 ng/g level) ranging from 74 +/- 4 to 103 +/- 9%. Samples naturally contaminated with cyclopiazonic and tenuazonic acids were found; estimated concentrations were 72 +/- 9 and 25 +/- 6 ng/g, respectively.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Evaluation of solid phase microextraction for the analysis of hydrophilic compounds.

Two commercially available solid phase microextraction (SPME) fibers, polyacrylate and carboxen/polydimethylsiloxane (PDMS), were evaluated for their ability to extract hydrophilic compounds from drinking water. Conditions, such as desorption time, desorption temperature, sample temperature, sample stirring, methanol concentration in the sample, and ionic strength of the sample, were optimized for 12 hydrophilic compounds (e.g., amines and alcohols) with both fibers. Accuracy, precision, and method detection limits (MDLs) were determined for the target analytes with both fibers. In general, both fibers exhibited excellent accuracy and precision in the range of 91-110% and 1.0-13%, respectively. The carboxen/PDMS fiber extracted these hydrophilic compounds from water with 10 to 100 times lower MDLs (0.10 to 15 micrograms/l) than the polyacrylate fiber (1.5 to 80 micrograms/l). The MDLs of the carboxen/PDMS fiber demonstrate that SPME is a feasible approach for extracting hydrophilic compounds from drinking water.

Environmental Monitoring↗
PubMed2000

Solid-phase microextraction for the assay of levomepromazine in human plasma.

Solid-phase microextraction (SPME) was investigated as sample preparation for the assay of the neuroleptic drug levomepromazine in human plasma. A mixture of human plasma, water, chloramitriptyline as internal standard, and aqueous NaOH was extracted with a 100-microm polydimethylsiloxane (PDMS) fiber (Supelco). The desorption of the fiber was performed in the injection port of a gas chromatograph at 260 degrees C [HP 5890; BPX-5 (SGE): 30 m x 0.53 mm ID, 1-microm film capillary; nitrogen-phosphorus selective detection]. As repeatedly found for SPME analysis of drugs in plasma, the recovery was low (i.e., 7% for levomepromazine). However, the analyte and internal standard were well separated and the calibration was linear from 5 to 180 ng/mL. The within-day precision was 2%, 4%, and 19% at concentrations of 160 ng/mL, 80 ng/mL, and 5 ng/mL, respectively. The between-day precision was 3%, 7%, and 19%, respectively. The limit of determination was 5 ng/mL. The comparison with an established liquid-liquid extraction gas-liquid chromatography method revealed good agreement for spiked samples and patient samples. No interfering peaks of drugs coadministered with levomepromazine or of endogenous substances were found. It is concluded that the method can be used in the therapeutic drug monitoring and clinical toxicology of levomepromazine.

Antipsychotic Agents↗
PubMedDate not supplied

Solid-phase microextraction for the enantiomeric analysis of flavors in beverages.

Solid-phase microextraction combined with gas chromatographic/mass spectrometric analysis and separation on a chiral cyclodextrin stationary phase was a rapid, reliable technique for profiling chiral aroma compounds in flavored alcoholic beverages. Several enantiomeric terpenes, esters, alcohols, norisoprenoids, and lactones were identified in berry-, peach-, strawberry-, and citrus-flavored wine and malt beverages (wine coolers). Using this technique, we were able to confirm the addition of synthetic flavoring to several beverages, consistent with label designations.

Alcoholic Beverages↗
PubMedDate not supplied

Determination of acrylamide formed in asparagine/D-glucose maillard model systems by using gas chromatography with headspace solid-phase microextraction.

A gas chromatographic method, along with a headspace solid-phase microextraction (HS-SPME), was developed for the determination of acrylamide formed in Maillard reaction model systems. The developed method was validated by liquid chromatography/mass spectrometry. A headspace sample was collected from an aqueous acrylamide solution (100 microg/mL) by SPME and directly injected into a gas chromatograph equipped with a nitrogen-phosphorus detector. The recovery of acrylamide from an aqueous solution was satisfactory, i.e, >93% under the conditions used. Acrylamide formed in an asparagine/D-glucose (molar ratio, 1/2) Maillard reaction model system heated at 150 and 170 degrees C for 20 min was collected and analyzed by the newly developed method using gas chromatography with nitrogen-phosphorus detection and HS-SPME. The amounts of acrylamide were 318 +/- 33 microg/g asparagine from a sample heated at 150 degrees C and 3329 +/- 176 microg/g asparagine from a sample heated at 170 degrees C. Addition of cysteamine or glutathione to the above model system reduced acrylamide formation. Acrylamide formation was not observed when cysteamine or glutathione was added to asparagine in the above model systems to obtain equimolar concentrations of both compounds. This newly developed method is simple and sensitive, and requires no solvent extraction.

Acrylamide↗
PubMed2004

Analysis of organochlorine pesticides in water by novel activated carbon fiber-solid phase microextraction coupled with gas chromatography-mass spectrometry.

This study describes a fast activated carbon fiber-solid phase microextraction (ACF-SPME) method for determining organochlorine pesticides (OCPs) in water. The pesticides in this study consist of Hexachlorobenzene (HCB) and alpha-, beta-, gamma-hexachlorocyclohexanes (HCHs). The optimal experimental procedures for the adsorption and desorption of four OCPs were evaluated. The linearity was obtained with a RSD of 20% for the OCPs studied over a range from 1.0 to 100 microg/L. The limits of detection at ng/L level were achieved with GC-MS under selected ion monitoring (SIM) acquisition mode. The proposed method was applied to the determination of OCPs concentration in tap water. The results have demonstrated the suitability of the ACF-SPME-GC-MS approach for the analysis of multi-residue OCPs in water. Compared to the commercial fiber, ACF has shown its advantages in solvent-resistance, thermal stability, and the cost. The results obtained in this study suggest that ACF is a promising choice in solid phase microextraction.

Adsorption↗
PubMed2003

Preferential extraction of hydrocarbons from fire debris samples by solid phase microextraction.

Headspace analysis by extraction/GC-MS is a common method of detecting volatile hydrocarbon accelerants in fire debris samples. Solid-phase microextraction was tested to determine if there is selective extraction of chemically distinct compounds. It was found that both the polydimethylsiloxane (PDMS) and Carboxen/PDMS solid phase microextraction fibers show preferential extraction of aliphatic or aromatic compounds from the headspace depending on fiber type and temperature. The Carboxen/PDMS fiber type showed particular (although not exclusive) selectivity for extraction of aromatic hydrocarbons. Other experimental considerations of SPME are noted.

Journal Article↗
PubMed2004

Application of solid-phase microextraction to the study of the photochemical behaviour of five priority pesticides: "on-fiber" and aqueous photodegradation.

Solid-phase microextraction (SPME) is applied to study the photochemical degradation of five priority pesticides: atrazine, alachlor, aldrin, dieldrin, endrin. Analyses were carried out by gas chromatography-mass spectrometry. The possibility of studying the photochemical degradation of the target compounds in solid-phase microextraction fibers, "photo-SPME", is evaluated employing different SPME coatings. The target analytes were extracted from aqueous solutions using different commercial coatings and then, the fibers were exposed to UV light. Results indicated that on-fiber photodegradation takes place in a considerably major extent using PDMS coating for an irradiation time of 30min. On-fiber photodegradation kinetics of each analyte were determined by UV irradiation of the PDMS for different times. A large number of photoproducts were generated and they were tentatively identified by means of their mass spectra and with the aid of literature. In this way, main photodegradation mechanisms could be postulated. Aqueous photodegradation studies followed by SPME were performed and compared with photo-SPME. All the photoproducts detected in the aqueous experiments were previously found in the photo-SPME experiments. This study shows the potential of photo-SPME to evaluate the photo-transformation of organic pollutants.

Gas Chromatography-Mass Spectrometry↗
PubMed1998

Application of solid-phase microextraction to the recovery of organic explosives.

The application of solid-phase microextraction to the recovery of residues of organic explosives by headspace sampling is discussed. It was found that the technique was rapid and simple. Polydimethylsiloxane and polyacrylate resin were examined as adsorption phases and the latter was found to be more effective. It was found that non-volatile explosives (PETN, RDX, and TNT) should be extracted at about 100 degrees. Acceptable limits of detection were achieved using bench top quadrupole mass spectrometry and short extraction times (about 30 min). Increasing the extraction times to many hours resulted in significantly enhanced detection. Desorption of PETN from the solid phase was found to induce some decomposition of the explosive, but the technique was still valuable for the analysis of this compound.

Acrylic Resins↗
PubMed2002

Biomimetic solid-phase microextraction to predict body residues and toxicity of chemicals that act by narcosis.

A biomimetic extraction technique using solid-phase microextraction (SPME) fibers has been developed for the risk assessment of contaminants with a narcotic mode of action. Our goal is to apply this technique in the future for the prediction of total baseline toxicity of environmental water and effluent samples. Validation of this method requires establishing the relationship between contaminant accumulation and toxicity in biota and accumulation in the surrogate solid phase (the SPME fiber coating). For this purpose, we determined the median lethal concentration (LC50) values for Chironomus riparius midge larvae exposed to two halogenated aromatic compounds separately and measured body residues in the exposed larvae. Solid-phase microextraction fibers with an 85-microm polyacrylate (PA) coating served as the surrogate hydrophobic phase, mimicking the uptake of the compounds by midge larvae. The toxicant concentrations in SPME fibers measured directly by gas chromatography/mass spectrometry (GC-MS) or calculated from the SPME fiber-water partition coefficient, K(SPME) were related to the toxicant concentrations found in midge larvae. Our results demonstrated that the biomimetic SPME method enables the estimation of body residues in biota and prediction of the degree of baseline toxicity of a water medium.

Animals↗
PubMed2006

Screening of tropical fruit volatile compounds using solid-phase microextraction (SPME) fibers and internally cooled SPME fiber.

In this study, the optimization and comparison of an internally cooled fiber [cold fiber with polydimethylsiloxane (PDMS) loading] and several commercial solid-phase microextraction (SPME) fibers for the extraction of volatile compounds from tropical fruits were performed. Automated headspace solid-phase microextraction (HS-SPME) using commercial fibers and an internally cooled SPME fiber device coupled to gas chromatography-mass spectrometry (GC-MS) was used to identify the volatile compounds of five tropical fruits. Pulps of yellow passion fruit (Passiflora edulis), cashew (Anacardium occidentale), tamarind (Tamarindus indica L.), acerola (Malphigia glabra L.), and guava (Psidium guajava L.) were sampled. The extraction conditions were optimized using two experimental designs (full factorial design and Doehlert matrix) to analyze the main and secondary effects. The volatile compounds tentatively identified included alcohols, esters, carbonyl compounds, and terpernes. It was found that the cold fiber was the most appropriate fiber for the purpose of extracting volatile compounds from the five fruit pulps studied.

Alcohols↗
PubMed1998

Effect of the various parameters governing solid-phase microextraction for the trace-determination of pesticides in water.

The parameters governing solid-phase microextraction (SPME) are investigated, with emphasis on the determination of the partition coefficients, K, and their use to predict the selection of a fibre, depending on the respective characteristics of the fibres and the analytes. Film thickness and stability of the compounds can interfere with the determination of K values. The time profile curves were determined for twelve pesticides having a wide range of water solubilities and polarities and using four fibres (polydimethylsiloxane, polydimethylsiloxane-divinylbenzene, Carbowax-divinylbenzene and polyacrylate). Although the affinity order was different for the four coatings, no correlation was found between the respective characteristics of the fibres and solutes. The two fibres containing divinylbenzene were shown to have the highest affinities and the polydimethylsiloxane had the lowest affinity. The polyacrylate fibre which is the more polar commercial fibre did not provide the highest affinities for the more polar and water-soluble analytes. The important parameters for quantitative analysis have been evaluated. The calibration curves were similar when one analyte of interest was present on its own in a drinking water sample, or when eleven other pesticides were present at the same concentration or when much higher concentrations of other analytes were present in the sample. Linearity was obtained over a wide range of concentrations in drinking water samples. Detection limits are in agreement with European regulatory levels in drinking water for most of the analytes using solid-phase microextraction-gas chromatography-nitrogen-phosphorus detection (SPME-GC-NPD). In contaminated surface water samples, the chromatograms are relatively clean and most of the compounds can be detected at levels lower than 0.5 microgram/l.

Calibration↗