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PubMed1999

Application of solid-phase microextraction to the profiling of an illicit drug: manufacturing impurities in illicit 4-methoxyamphetamine.

This article describes the application of solid-phase microextraction (SPME) to the recovery of manufacturing by-products and impurities from an illicit drug seizure. The preparation chosen for examination using this technique contained 4-methoxyamphetamine, an hallucinogenic amphetamine that has been encountered frequently in South Australia. Compounds found in the PMA preparation included 4-methoxyphenol, 4-methoxybenzaldehyde, 4-methoxyphenyl-2-propanone, 4-methoxyphenyl-2-propanol, 4-methoxyphenyl-propene, and (tentatively) 4-methyl-5-(4'-methoxyphenyl) pyrimidine. The presence of these compounds suggests that the active drug was prepared from 4-methoxybenzaldehyde via 4-methoxyphenyl-2-propanone using a Leuckardt reductive amination. In this instance, SPME was found to be a simple, rapid, and non-destructive recovery technique that gave results complementary to those provided by conventional liquid-liquid extraction. There is an indication that SPME might find application in profiling of illicit drugs.

Amphetamines↗

PubMed2002

[Determination of trace chrysene in environmental water by solid-phase microextraction coupled with high performance liquid chromatography].

A rapid method for the determination of trace chrysene in environmental water by solid-phase microextraction (SPME) coupled with high performmnce liquid chromatography (HPLC) was developed. The experimental conditions of SPME, such as extraction time, extraction temperature, effect of ion strength, desorption time, desorption solution, desorption mode and the analytical conditions of HPLC were optimized. The optimal conditions were room temperature, 1,100 r/min of stirring rate, 30 min of extraction time, 3 min of desorption time, and methanol as the desorption solution. Methanol was used as the mobile phase on a C18 reversed phase chromatographic column. The flow rate was 1 mL/min. The detection wavelength was 266 nm on a UV-Vis detector. The linear range was from 0.013 microgram/L to 3.0 micrograms/L, the detection limit was 2.7 ng/L, and the relative standard deviation (RSD) was 5.6%. The method was used for the determination of trace chrysene in tap water, mineral water, rain water and river water. The recoveries were from 103.2% to 119.3%, the RSDs were from 4.8% to 10.2%. The method is fast, convenient, sensitive, solvent-free, and suitable for the determination of trace chrysene in environmental water.

Chromatography, Gas↗

PubMed2004

Application of a novel sol-gel polydimethylsiloxane-poly(vinyl alcohol) solid-phase microextraction fiber for gas chromatographic determination of pesticide residues in herbal infusions.

A simple and environmentally friendly methodology for headspace solid-phase microextraction (HS-SPME) using a new fiber coated with polydimethylsiloxane-poly(vinyl alcohol) (PDMS/PVA) is reported for the trace determination of organochlorine (OCP) and organophosphorus (OPP) pesticides in herbal infusions of Passiflora L. by GC-ECD. The capacity of the PDMS/PVA coating for the pesticides was compared to that of commercial PDMS fibers, with advantageous results. The effects of parameters such as the sample ionic strength, dilution of the infusion, extraction temperature and time were investigated. The optimized conditions for the determination of OCP and OPP in Passiflora L. infusions were extraction time and temperature, respectively, of 38 min and 67.5 degrees C, with 5 min of sample/headspace equilibration time. The analytical curves for the range between 0.04 ng mL(-1) to 6 ng mL(-1) of each compound presented a good quality (correlation coefficients of 0.921 or better). The detection limits for the OCP and OPP in these matrices varied from 0.01 ng mL(-1) (beta-endosulfan) to 1.5 ng mL(-1) (malathion). The sensitivity of studied methodology was adequate, as well as its accuracy (78.7-91.5%) and precision (R.S.D. = 1.2-14.2%).

Chromatography, Gas↗

PubMed2006

Simultaneous determination of selegiline and desmethylselegiline in human body fluids by headspace solid-phase microextraction and gas chromatography-mass spectrometry.

A method for the simultaneous determination of selegiline and its metabolite, desmethylselegiline, in human whole blood and urine is presented. The method, which combines a fiber-based headspace solid-phase microextraction (SPME) technique with gas chromatography-mass spectrometry (GC-MS), required optimization of various parameters (e.g., salt additives, extraction temperatures, extraction times and the extraction properties of the SPME fiber coatings). Pargyline was used as the internal standard. Extraction efficiencies for both selegiline and desmethylselegiline were 2.0-3.4% for whole blood, and 8.0-13.2% for urine. The regression equations for selegiline and desmethylselegiline extracted from whole blood were linear (r(2)=0.996 and 0.995) within the concentration ranges 0.1-10 and 0.2-20 ng/ml, respectively. For urine, the regression equations for selegiline and desmethylselegiline were linear (r(2)=0.999 and 0.998) within the concentration ranges 0.05-5.0 and 0.1-10 ng/ml, respectively. The limit of detection for selegiline and desmethylselegiline was 0.01-0.05 ng/ml for both samples. The lower and upper limits of quantification for each compound were 0.05-0.2 and 5-20 ng/ml, respectively. Intra- and inter-day coefficients of variation for selegiline and desmethylselegiline in both samples were not greater than 8.7 and 11.7%, respectively. The determination of selegiline and desmethylselegiline concentrations in Parkinson's disease patients undergoing continuous selegiline treatment is presented and is shown to validate the present methodology.

Amphetamines↗

PubMed2000

Validation of negligible depletion solid-phase microextraction as a tool to determine tissue/blood partition coefficients for semivolatile and nonvolatile organic chemicals.

In the current study, negligible depletion solid-phase microextraction (nd-SPME) as a technique to determine tissue/blood (tissue/water and blood/water) partition coefficients was validated. With this method the free fraction of chemicals in water in the presence of different tissues was determined and, subsequently, the partition coefficients were calculated. Liver, blood, muscle, and fat tissues obtained from male Wistar-derived rats (U:Wu) were used without homogenization. Data obtained were compared with literature data for lindane, parathion, and paraoxon. The results show that the data in the present work differ by less than a factor of two from those reported in literature. In addition, the standard deviations obtained show that the technique is accurate. Therefore, we conclude that this accurate and automated method can be used to determine tissue/blood partition coefficients for semivolatile and nonvolatile chemicals.

Adipose Tissue↗

PubMed1995

A simple analysis of 5 thinner components in human body fluids by headspace solid-phase microextraction (SPME).

A simple method for the extraction of 5 thinner components from human whole blood and urine, using the headspace solid-phase microextraction (SPME) method is presented. After heating a vial containing the samples with 5 compounds (toluene, benzene, n-butyl acetate, n-butanol and n-isoamyl acetate) at 80 degrees C, a polydimethylsiloxane-coated SPME fiber was exposed to the headspace of the vial to allow adsorption of the compounds. The fiber needle was then injected into a capillary gas chromatography (GC) port. The headspace SPME-GC gave intense peaks for each compound and a low level of background noise was seen only for whole blood. Recovery rates of the 5 compounds by use of the headspace SPME-GC were 50-70%. Reproducibility for headspace SPME-GC data were excellent for both body fluids. The calibration curves showed linearity in the range 2-100 ng/0.5 ml whole blood or urine. The detection limits of each compound were 1.1-2.4 ng/0.5 ml sample. The present results on the analysis of 5 thinner components by headspace SPME-GC suggest its applicability to a number of other volatile compounds in forensic toxicology.

1-Butanol↗

PubMed2004

Improvements in the methylmercury extraction from human hair by headspace solid-phase microextraction followed by gas-chromatography cold-vapour atomic fluorescence spectrometry.

Improvements in the methylmercury extraction from human hair by solid-phase microextraction followed by gas chromatography coupled to cold-vapour atomic fluorescence spectrometry (GC-CVAFS) have been carried out. They consisted in the optimisation of the digestion step prior to the aqueous-phase ethylation and in the GC-CVAFS interface set-up. The main digestion parameters such as acid type, concentration, temperature and time have been optimised for hair sample analysis, thereby avoiding methylmercury degradation. Moreover, the stability of the digested samples was evaluated to improve the sample throughput.

Chromatography, Gas↗

PubMed2003

Reevaluation of headspace solid-phase microextraction and gas chromatography-mass spectrometry for the determination of methyl tert-butyl ether in water samples.

A headspace solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) method has been reevaluated for the determination of methyl tert-butyl ether (MTBE) in water. Factors affecting method performance were examined. The internal standard, deuterated MTBE, is necessary because it allows normalization of the calibration since the deuterated MTBE and MTBE experience the same extraction efficiency. The method detection limit was 6.6 ng/l, with a linear range up to 160 microg/l. SPME extraction efficiency and detection sensitivity for MTBE decreased in the presence of gasoline matrix. However, reliable measurement of MTBE was possible in the background matrix concentration of 0.97 mg/l gasoline using deuterated internal standard. Reproducibility was 4.5% at the spiking level of 47 ng/l. The average recoveries of MTBE in spiked fountain water, tap water, and snow at 60 ng/l and in spiked rainwater at 580 ng/l ranged from 101 to 105%. The method was successfully applied to the analysis of trace levels of MTBE in various water samples, including rain and snow samples collected in Albany, NY, USA.

Calibration↗

PubMed2005

Highly porous solid-phase microextraction fiber coating based on poly(ethylene glycol)-modified ormosils synthesized by sol-gel technology.

The preparation and characteristics of solid-phase microextraction (SPME) fibers coated with Carbowax 20M ormosil (organically modified silica) are described here. Raw fused silica fibers were coated with Carbowax 20M-modified silica using sol-gel process. Scanning electron micrographs of fibers revealed a highly porous, sponge-like coating with an average thickness of (8 +/- 1) microm. The sol-gel Carbowax fibers were compared to commercial fibers coated with 100 microm polydimethylsiloxane (PDMS) and 65 microm Carbowax-divinylbenzene (DVB). Shorter equilibrium times were possible with the sol-gel Carbowax fiber: for headspace extraction of the test analytes, they ranged from less than 3 min for benzene to 15 min for o-xylene. Extraction efficiencies of the sol-gel Carbowax fiber were superior to those of conventional fibers: for o-xylene, the extracted masses were 230 and 540% of that obtained with 100 microm PDMS and 65 microm Carbowax-DVB fibers, respectively.

Benzene↗

PubMed2006

Preparation and characteristics of high pH-resistant sol-gel alumina-based hybrid organic-inorganic coating for solid-phase microextraction of polar compounds.

A novel alumina-based hybrid organic-inorganic sol-gel coating was first developed for solid-phase microextraction (SPME) from a highly reactive alkoxide precursor, aluminum sec-butoxide, and a sol-gel-active organic polymer hydroxyl-terminated polydimethylsiloxane (OH-TSO). The underlying mechanism was discussed and confirmed by IR spectra. The porous surface structure of the sol-gel coating was revealed by scanning electron microscopy. A detailed investigation was conducted to evaluate the remarked performance of the newly developed sol-gel alumina-OH-TSO hybrid materials. In stark contrast to the sol-gel silica-based coating, the alumina-based coating demonstrated excellent pH stability. In addition, good thermal resistance and coating preparation reproducibility are also its outstanding performance. As compared to silica-based hybrids material, the ligand exchange ability of alumina makes it structurally superior extraction sorbents for polar compounds, such as fatty acids, phenols, alcohols, aldehydes and amines. Practical applicability of the prepared alumina-OH-TSO fiber was demonstrated through the analysis of volatile alcohols and fatty acids in beer. The recoveries obtained ranged from 85.7 to 104% and the relative standard deviation values for all analytes were below 9%.

Aluminum Oxide↗

PubMed2006

Solid-phase microextraction of N-nitrosamines.

A method was developed for the extraction of seven N-nitrosamine compounds from water by solid-phase microextraction (SPME). The method developed requires a total analysis time of only 1.25 h for both extraction and detection (versus 3-20 h for other isolation techniques). Three gas chromatography (GC) detection systems were tested with the SPME method, nitrogen chemiluminesence detection (NCD), nitrogen-phosphorus detection (NPD) and chemical ionization mass spectrometry (CI-MS), with method detection limits (MDLs) found in the ng/L range. This method was used to analyze wastewater samples and showed excellent selectivity of extraction. The detection limits of this method for N-nitrosodimethylamine (NDMA) range from 30 to 890 ng/L as a function of detector type. The excellent selectivity of SPME in addition to the fast analysis time would make this method ideal for general surveys, wastewater analysis and laboratory studies (e.g. degradation kinetics or formation potential).

Chromatography, Gas↗

PubMed2000

Evolution of solid-phase microextraction technology.

The main objective of this contribution is to describe the development of the concepts, techniques and devices associated with solid-phase microextraction, as a response to the evolution of understanding of the fundamental principles behind this technique. The discussion begins with an historical perspective on the very early work conduced almost a decade ago. As new fundamental understanding about the functioning of the technology developed, new ways of constructing and using the SPME devices evolved.

Chromatography, Liquid↗

PubMed2001

Solid-phase microextraction method for the determination of atrazine and four organophosphorus pesticides in soil samples by gas chromatography.

A simple and rapid solid-phase microextraction (SPME) based method is presented for the simultaneous determination of atrazine and four organophosphorus (i.e. parathion-methyl, chlorpyriphos, methidathion and carbophenothion) in soils. After optimisation of the different experimental variables affecting the SPME of the target compounds from aqueous solutions by using an experimental design, a consensus strategy was adopted which allowed the use of the SPME method developed for the simultaneous screening of all the analytes selected. The complete analytical procedure finally proposed consisted of a 15-min ultrasonic extraction of the target compounds from a 0.5-g soil sample with 5 ml of methanol and the dilution of this extract to up 10% methanol followed by the addition of NaCl to a final concentration of 10% (w/v). The analytes in this aqueous extract were preconcentrated for 30 min in the SPME fiber and subsequently desorbed by heating of the fiber at 260 degrees C for 5 min in the gas chromatograph injection port. Final determination was carried out with an electron-capture detector. The recoveries of the pesticides studied in soils ranged from 72 to 123%, except for atrazine, and the SDs were below 16%. The feasibility of the procedure finally proposed for the screening of the endogenous pesticides irrespective of the properties of the soil selected has been shown.

Atrazine↗

PubMed2002

Photolysis of polychlorinated biphenyls by solid-phase microextraction. "On-fibre" versus aqueous photodegradation.

The photodegradation kinetics of polychlorinated biphenyls "on-fibre" is described. The utilisation of solid-phase microextraction (SPME) fibres to monitor photolysis pathways and determine photoproducts constitutes a new approach that exploits the solvent-free aspect and concentration possibilities of this technique. Direct photolysis of aqueous solutions containing polychlorinated biphenyls (PCBs) was also undertaken and SPME was used in this case for photoproduct extraction purposes. Reductive dechlorination was the main decomposition mechanism in both procedures. Less-chlorinated biphenyls are the principal photoproducts and, among these, some toxic coplanar species have been detected. The influence of irradiation time was evaluated for both treatments. SPME was found to be a good choice for the extraction of photoproducts in experiments conducted in the classical way (extraction after photolysis). Moreover, it is demonstrated that photolysis of PCBs "on fibre" is realistic and provides the possibility of evaluating the phototransformation of these pollutants at environmental levels.

Mass Spectrometry↗

PubMed2003

Development of a quantification method for the analysis of malodorous sulphur compounds in gaseous industrial effluents by solid-phase microextraction and gas chromatography-pulsed flame photometric detection.

A quantification method for malodorous sulphur compounds in gaseous industrial effluents using solid-phase microextraction sampling followed by gas chromatography-pulsed flame photometric detection has been developed. A comparative study showed that polydimethylsiloxane-Carboxen fibre led to sufficient sensitivity to achieve the microg m(-3) human perception levels of the five analytes studied (hydrogen sulphide, methanethiol, ethanethiol, dimethyl sulphide, dimethyl disulphide). However, this coating is known to suffer from competitive adsorption, which may lead to inaccurate quantification. Therefore, external calibration can only be used under a limited range of concentrations, which were determined from Fick's diffusion law. This approach was tested on a real gaseous sample and compared with the standard addition method. Good correlations were found for ethanethiol, dimethyl sulphide and dimethyl disulphide. However, for more volatile sulphur compounds (i.e., hydrogen sulphide and methanethiol), the easy-to-use external calibration could not be applied and standard additions had to be performed for accurate quantification.

Calibration↗

PubMed1998

Application of solid-phase microextraction and gas chromatography-mass spectrometry for the determination of chlorophenols in urine.

This study investigated the feasibility of applying solid-phase microextraction (SPME) combined with gas chromatography-mass spectrometry to analyze chlorophenols in urine. The SPME experimental procedures to extract chlorophenols in urine were optimized with a polar polyacrylate coated fiber at pH 1, extraction time for 50 min and desorption in GC injector at 290 degrees C for 2 min. The linearity was obtained with a precision below 10% R.S.D. for the studied chlorophenols in a wide range from 0.1 to 100 microg/l. In addition, sample extraction by SPME was used to estimate the detection limits of chlorophenols in urine, with selected ion monitoring of GC-MS operated in the electron impact mode and negative chemical ionization mode. Detection limits were obtained at the low ng/l levels. The application of the methods to the determination of chlorophenols in real samples was tested by analyzing urine samples of sawmill workers. The chlorophenols were found in workers, the urinary concentration ranging from 0.02 microg/l (PCP) to 1.56 microg/l (2,4-DCP) depending on chlorophenols. The results show that trace chlorophenols have been detected with SPME-GC-MS in the workers of sawmill where chlorophenol-containing anti-stain agents had been previously used.

Chlorophenols↗

PubMed1997

Rapid analysis of malathion in blood using head space-solid phase microextraction and selected ion monitoring.

A simple and rapid method for analysis of malathion in blood was developed using head space-solid phase microextraction (HS-SPME) and gas chromatography mass spectrometry/ electron impact ionization-selected ion monitoring (GC-MS/EI-SIM). A vial containing a blood sample, ammonium sulphate, sulphuric acid and fenitrothion as an internal standard, was heated at 90 degrees C for 15 min. The extraction fiber of the SPME was exposed for 5 min in the head space of the vial. The compounds absorbed on the fiber were detached by exposing the fibre in the injection port of GC-MS. A straight calibration curve was obtained between malathion concentrations of 2.5 to 50.0 micrograms g-1 in blood. No interfering substances were found, and the time for analysis was 40 min for one sample.

Adult↗

PubMed2001

Application of solid-phase microextraction in the determination of diazepam binding to human serum albumin.

In this paper, protein-drug interactions were studied by solid-phase microextraction (SPME) using diazepam binding to human serum albumin as a model system. Since drug compounds are normally polar and nonvolatile by nature, direct SPME is used in this work. The SPME extraction is an equilibrium process among the concentrations of the analyte partitioned onto the SPME fiber, free and bound drug in the solution. A calibration curve was first constructed by employing the amount of the analytes partitioned on the fiber versus the free analyte concentration in the solution in the absence of protein. In method I, the extraction was performed in the protein solution with known diazepam concentration. In method II, diazepam was first loaded onto the fiber by extracting in solution with known diazepam concentration. This fiber was subsequently transferred into the protein solution for desorption. The amount of the analyte left on the fiber was analyzed after the system reached equilibrium. The free drug concentration was then obtained from the calibration curve for both methods. The Scatchard plot was finally employed to obtain the number of binding sites and the equilibrium binding constants. Since only a very small amount of the protein solution is required (150 microL for each extraction), method II is very useful for circumstances where the protein amount is very limited. The direct measurement method proposed in this paper does not need a GC response factor, which significantly decreases the experimental error. The only measurement needed is the area count change (ratio) of the fiber injections before and after the protein was introduced into the solution. The difference between the direct measurement method for method I and method II is discussed. The result illustrated that the SPME direct measurement method provided both theoretical accuracy and simplicity in such applications.

Calibration↗