Microextraction Fiber Research Articles

Three-phase hollow fiber liquid-phase microextraction based on two immiscible organic solvents for determination of tramadol in urine and plasma samples

Recently, the new concept of three-phase liquid microextraction was introduced based on applying two immiscible organic solvents in lumen and wall pores of hollow fiber. In the present work, this novel microextraction technique combined with gas chromatography–mass spectrometry has been developed for determination of tramadol, an analgesic agent, in plasma and urine samples. A systematic investigation of the proposed method was applied to find optimal extraction conditions and evaluate the interaction effects between the factors by designing experiments according to the methodology of Box–Behnken response surface design. Analysis of variance (ANOVA) revealed that the important factors contributing to extraction efficiency are extraction time, stirring rate and hollow fiber length. Under the optimum conditions, the developed method provided a preconcentration factor of 546, good repeatability (RSD % = 6.4), and good linearity ( r 2 = 0.995) for spiked plasma and urine real samples. The linear dynamic range from 0.1 to 400 μg L −1 and limit of detection (LOD) of 0.08 μg L −1 were obtained under selected ion monitoring mode. The results demonstrated that three-phase hollow fiber microextraction based on two immiscible solvents is a simple and accurate technique with very good preconcentration factor and clean-up for extraction of tramadol from biological samples.

Ultrasonic nebulization extraction coupled with headspace hollow fiber microextraction of pesticides from root of Panax ginseng C.A. Mey.

The ultrasonic nebulization extraction coupled with headspace hollow fiber microextraction (UNE-HS-HFME) was applied for the extraction of pesticides from root of Panax ginseng C.A. Mey. Experimental parameters, which affect the performances of ultrasonic nebulization extraction coupled with headspace hollow fiber microextraction, such as the kind of acceptor solvent in the pore of the fiber wall, the sample amount, extraction time, salt concentration in extraction solvent, pH of the acceptor solution, the elution time, and times were studied and optimized. The analytes were determined by high-performance liquid chromatography. The detection limits for simeton, monolinuron, chlortoluron, karmex, and prebane are 20.9, 18.4, 18.2, 12.4, and 22.2 μg/kg, respectively. Besides volatile and semi-volatile compounds, the non-volatile compounds also can be determined by the proposed method. The extraction and enrichment process can be performed simultaneously.

Optimization of carrier-mediated three-phase hollow fiber microextraction combined with HPLC-UV for determination of propylthiouracil in biological samples

Carrier-mediated three-phase hollow fiber microextraction combined with high-performance liquid chromatography-ultra violet detection (HPLC-UV) was applied for the extraction and determination of propylthiouracil in biological samples. Propylthiouracil (PTU) was extracted from 7.5 mL of the basic solution (the source phase) with pH 12 into an organic phase ( n-octanol containing 6% (w/v) of Aliquat 336 as the carrier) impregnated in the pores of a hollow fiber, and finally was back extracted into 24 μL of the acidic solution located inside the lumen of the hollow fiber (the receiving phase). The extraction was performed through the gradient of counter ion from the source to the receiving phase. The effects of different variables on the extraction efficiency were studied simultaneously using an experimental design. A half-fractional factorial design was employed for screening to determine the variables significantly affecting the extraction efficiency. Then, the factors with significant effect were optimized using a central composite design (CCD) and the response surface equations were developed. The optimal experimental conditions obtained from this statistical evaluation included: source phase, pH 12; temperature, 25 °C; extraction time, 40 min; counter ion concentration, 2 mol L −1 of NaClO 4; organic solvent 6% of Aliquat in octanol and without salt addition in the source phase. Under the optimized conditions, the preconcentration factors were between 125 and 198 and also the limit of detections (LODs) ranged from 0.1 μg L −1 to 0.4 μg L −1 in different biological samples. The calibration curve was linear ( r 2 = 0.998) in the concentration range of 0.5–1000 μg L −1. Finally, the feasibility of the proposed method was successfully confirmed by extraction and determination of PTU in human plasma and urine as well as the bovine milk and meat samples in microgram per liter, and suitable results were obtained (RSDs < 6.3%).

A novel approach to automation of dynamic hollow fiber liquid‐phase microextraction

An automated dynamic two-phase hollow fiber microextraction apparatus combined with high-performance liquid chromatography was developed for extraction and determination of chlorophenoxy acid (CPA) herbicides from environmental samples. The extraction device, called TT-extractor, consists of a polypropylene hollow fiber mounted inside a stainless steel tube by means of two tee-connectors in flow system. An organic solvent, which fills the lumen and the pores of the hydrophobic fiber, is pumped through the fiber repeatedly and the sample is pumped along the outer side of the fiber. The factors affecting the dynamic hollow fiber liquid-phase microextraction (DHF-LPME) of target analytes were investigated and the optimal extraction conditions were established. To test the applicability of the designed instrument, CPAs were extracted from environmental aqueous samples. The limits of detection (LODs) as low as 0.5 μg/L, linear dynamic range in the range of 1-100 μg/L and the relative standard deviations of <7% were obtained. The developed method can provide perconcentration factors as large as 230. A hollow fiber membrane can be used at least 20 times with neither loss in the efficiency nor carryover of the analytes between runs. The system is cheap and convenient and requires minimal manual handling.

Determination of 4 phenols in water by three phase hollow fiber microextraction coupled with high performance liquid chromatography

A method was investigated for the determination of 4 phenols in water by three phase hollow fiber microextraction coupled with high performance liquid chromatography. Some factors affecting the extraction efficiency were optimized, such as the nature of organic solvent, the concentration of acceptor phase, the pH value of donor phase, extraction time, stirring rate and salt concentration. The optimized conditions were as follows: 1-octanol was used as the organic solvent, the concentration of NaOH solution as acceptor phase was 0.09 mol/L, the pH value of donor phase was 4, the extraction time was 40 min, the stirring rate was 600 r/min and the NaCI concentration was 100 g/L. Under the optimal conditions, the detection limits (S/N = 3) of phenol, 4-methylphenol, 2,4-dimethylphenol and 2-naphthol were 0.4, 0.4, 1.2 and 0.4 microg/L, and the enrichment factors were 111.6, 129.5, 71.0 and 175.6, respectively. The proposed method was applied for the determination of the 4 phenols in real environmental water samples and the spiked recoveries were in the range of 85.9%-119.0% at the spiked levels of 5 and 50 microg/L. The method is simple, rapid, accurate and suitable for the determination of phenols in water samples.

Electrospray ionization-ion mobility spectrometry as a detection system for three-phase hollow fiber microextraction technique and simultaneous determination of trimipramine and desipramine in urine and plasma samples

A novel method based on three-phase hollow fiber microextraction technique (HF-LPME) coupled with electrospray ionization-ion mobility spectrometry (ESI-IMS) was developed for the simultaneous determination of two antidepressant drugs (trimipramine and desipramine) in urine and plasma samples. The effects of various parameters such as type of organic solvent, composition of donor and acceptor phase, stirring rate, salt addition, extraction time, and temperature were investigated. Under the optimized conditions, the relative standard deviation was in the range of 5-6%, and the method quantitation limit (MQL) of utilizing HF-LPME/ESI-IMS was 5 μg/L for both drugs. The relative recoveries obtained by the proposed method from urine and plasma samples were in the range 94% to 97% for trimipramine and 92% to 96% for desipramine. Finally, the feasibility of the proposed method was successfully confirmed by extraction and determination of trace amounts of trimipramine and desipramine in biological samples without any significant matrix effect.

New SPME fibre for analysis of mequinol emitted from DVDs

AbstractA piece of fused-silica fibre coated with silica modified with ketamine-groups was used as a solidphase microextraction (SPME) fibre and its efficiency in the qualitative and quantitative analysis of volatile organic compounds released from coloured overprinting on DVDs was evaluated. The effect of the parameters that can affect the SPME procedure, such as extraction time, extraction temperature, desorption temperature, was investigated to determine the analytical performance of this novel fibre in the qualitative and quantitative analyses of organic compounds. The optimised procedure was applied to the qualitative and quantitative analyses of organic compounds released from coloured overprinting on DVDs. The limit of detection of 4-methoxyphenol (mequinol) was 88 × 10−3 μg mL−1, while the limit of quantification (LOQ) was calculated as ten times the baseline noise, i.e. 3.1 × 10−1 μg mL−1. The proposed fibre was used successfully for preconcentration of the volatile organic compounds from the gaseous phase of DVD samples.

Three-phase hollow fiber microextraction based on carrier-mediated transport combined with HPLC-UV for the analysis of dexamethasone sodium phosphate in biological samples

A three-phase hollow fiber microextraction technique based on carrier mediated transport combined with high performance liquid chromatography-ultra violet detection (HPLC-UV) was applied in the extraction and determination of dexamethasone sodium phosphate in biological samples. Dexamethasone sodium phosphate (DSP) was extracted from 7.5 mL of acidic solution (source phase) of pH 3 into an organic phase (n-octanol containing 5% (w v−1) of Aliquate-336 as carrier) impregnated in the pores of a hollow fiber and finally back extracted into 24 μL of a basic solution (pH = 9.5) located inside the lumen of the hollow fiber (receiving phase). The extraction took place due to the gradient of the counter ion from the source to the receiving phase. In order to achieve maximum extraction efficiency, different parameters affecting the extraction conditions were optimized. Under the optimized conditions, a preconcentration factor of 276 and detection limit (LOD) of 0.2 μg L−1 were obtained. The calibration curve was linear (r2 = 0.998) in the concentration range of 1–1000 μg L−1. Finally, the feasibility of the proposed method was successfully confirmed by extraction and determination of DSP in bovine milk, human plasma and urine samples in the range of microgram per liter and suitable results were obtained (RSDs < 7.2%).

Dynamic three-phase hollow fiber microextraction based on two immiscible organic solvents with automated movement of the acceptor phase

Dynamic three-phase hollow fiber liquid-liquid-liquid microextraction (HF-LLLME) based on two immiscible organic solvents, with automated movement of organic acceptor phase to facilitate mass transfer was introduced for the first time. Polycyclic aromatic hydrocarbons were used as model compounds and extracted from water and soil samples. The extraction involved filling an 8 cm length of hollow fiber with 25 μL of organic acceptor solvent using a microsyringe, followed by impregnation of the pores in the fiber wall with n-dodecane. The fiber was then immersed in 20 mL of aqueous sample solution. During extraction, the organic acceptor phase was repeatedly moved in the lumen of the hollow fiber by movement of the syringe plunger controlled by programmable syringe pump. Following this microextraction, 2 μL of organic acceptor phase was injected into gas chromatography-flame ionization detector. This new technique provided up to 554-fold preconcentration of the analytes under the optimized conditions. Good repeatabilities (with RSDs ≤8.4%) were obtained. Detection limits were in the range of 0.2-0.5 μg/L. The utilization of the proposed method for extraction of the polycyclic aromatic hydrocarbons from different real samples (such as water and soil samples) also gave good precision and recovery.

Multiwalled Carbon Nanotube Coated on Stainless Steel Wire for Solid-Phase Microextraction of Organochlorine Pesticides in Water

A novel solid-phase microextraction (SPME) fiber was prepared by coating multiwalled carbon nanotube (MWCNTs) on a stainless steel wire, and its characteristics were studied. To evaluate the MWCNTs coating, the fiber was used for the extraction of some organochlorine pesticides (OCPs) from water samples by Headspace SPME (HS-SPME) mode. Potential factors affecting the extraction efficiency such as extraction time, extraction temperature, agitation, ionic strength, desorption temperature, and time were also optimized. Several experiments were carried out by water spiked with target compounds to evaluate the analytical characteristics of the proposed method under optimized conditions. The linearity was from 0.1 to 10 ug/L with the linear correlation coefficients (r) ranging from 0.9956 to 0.9995. The limits of detection (LOD, S/N = 3) for these pesticides were between 0.43 and 2.13 ng/L and the precision (RSD, n = 5) was 2.53–12.25%. When this method was applied for the spiked real river sample, the relative recoveries ranged from 72.4% to 134.7% for the tested OCPs.

Analysis of mono-nitrotoluenes in water samples by using nano-structured polypyrrol as a sorbent of solid-phase microextraction

Nano-structured polypyrrole (PPY) was used as a coating of solid-phase microextraction (SPME) fibre to increase the extraction efficiency of headspace solid phase microextraction (HS-SPME) of mono-nitrotoluene (MNT) isomers in water samples. The nano-structured PPY was prepared electrochemically by template-free method in the presence of dodecylbenzene sulphonate (DBS) as dopant. Nano-fibrous structures of PPY with a diameter in the range of 38–129 nm were obtained. The porous surface structure of the film, revealed by scanning electron microscopy (SEM), provided high surface areas and allowed for high extraction efficiency of MNT isomers. The extraction procedure was optimised by selecting the appropriate extraction parameters including the time and temperature of adsorption, salt concentration and stirring rate. The calibration graphs obtained by HS-SPME using the proposed fibre followed by GC-FID analysis were linear in a concentration range of 0.1–500 µg L−1 (r > 0.999) with detection limits below 0.012 µg L−1 for three isomers. Repeatability of the method was less than 6% (RSD%, n = 4). Good recoveries (88–108%) were obtained for the extraction of mono-nitrotoluenes in real water samples.

Hollow fiber-based liquid phase microextraction combined with high-performance liquid chromatography for the analysis of gabapentin in biological samples

Three-phase hollow fiber microextraction technique combined with high performance liquid chromatography-ultra violet (HPLC-UV) was applied for the extraction and determination of gabapentin in biological fluids. Gabapentin (GBP) was derivatized with 1-fluoro-2,4-dinitrobenzene, as a UV absorbent agent in borate buffer (pH 8.2) before extraction. The derivative product of GBP was extracted from the 8.5 mL of acidic solution (source phase) into an organic phase (dihexyl ether) impregnated in the pores of a hollow fiber and finally back-extracted into 24 μL of the basic solution (pH 9.1) located inside the lumen of the hollow fiber (receiving phase). The extraction took place due to pH gradient between the inside and outside of the hollow fiber membrane. In order to achieve maximum extraction efficiency, different parameters affecting the extraction conditions were optimized. Under the optimized conditions, preconcentration factor of 95 and detection limit (LOD) of 0.2 μg L −1 were obtained. The calibration graph was linear within the range of 0.6–5000 μg L −1. Finally, the feasibility of the proposed method was successfully confirmed by extraction and determination of GBP in human urine and plasma samples in the range of microgram per liter and suitable results were obtained (RSDs < 6.3%).

Carbon monolith: Preparation, characterization and application as microextraction fiber

A carbon monolith was synthesized via a polymerization–carbonization method, styrene and divinylbenzene being adopted as precursors and dodecanol as a porogen during polymerization. The resultant monolith had bimodal porous substructure, narrowly distributed nano skeleton pores and uniform textural pores or throughpores. The carbon monolith was directly used as an extracting fiber, taking place of the coated silica fibers in commercially available solid-phase microextraction device, for the extraction of phenols followed by gas chromatography–mass spectrometry. Under the studied conditions, the calibration curves were linear from 0.5 to 50 ng mL −1 for phenol, o-nitrophenol, 2,4-dichlorophenol and p-chlorophenol. The limits of detection were between 0.04 and 0.43 ng mL −1. The recoveries of the phenols spiked in real water samples at 10 ng mL −1 were between 85% and 98% with the relative standard deviations below 10%. Compared with the commercial coated ones (e.g. PDMS, CW/DVB and DVB/CAR/PDMS), the carbon monolith-based fiber had advantages of faster extraction equilibrium and higher extraction capacity due to the superior pore connectivity and pore openness resulting from its bimodal porous substructure.

인공타액처리에 의한 수삼의 향기성분 변화 분석

The volatile constituents of the fresh roots of Panax ginseng C.A. Meyer have been investigated after treatment with artificial saliva and analysed by gas chromatography-mass spectrometry (GC-MS) using solid phase microextraction (SPME) fiber. Twenty peaks were detected in fresh ginseng, 5 of them were unknown peak, and mainly hydrocarbon components (α-pinene, β-pinene, myrcene, limonene, β-panasinsene, β-elemene, β-gurjunene, trans-caryophyllene, α-gurjunene, α-panasinsene, α-neoclovene, trans-β-farnasene, α-humulene, β-neoclovene, α-selinene, β-selinene, bycyclogermacrene) were detected. It's area percentage was increased about 10% in the fresh ginseng added artificial saliva during 40 minutes.

Ultratrace analysis of uracil and 5‐fluorouracil by molecularly imprinted polymer brushes grafted to silylated solid‐phase microextraction fiber in combination with complementary molecularly imprinted polymer‐based sensor

Main inborn errors of metabolism diagnosable through uracil (Ura) analysis and the therapeutic monitoring of toxic 5-fluorouracil (5FU) in dihydro pyrimidine dehydrogenase (DPD) deficient patients require a sensitive, reproducible, selective and accurate method. In this work, an artificial receptor in the format of molecularly imprinted polymer (MIP) brush 'grafted to' the surface of sol-gel immobilized on cost-effective homemade solid-phase microextraction (SPME) fibers, individually imprinted with either of Ura and 5FU, was used in combination with a voltammetric sensor duly modified with the same MIP. This combination provided up to 10- and 8.4-fold preconcentrations of Ura and 5FU, respectively, which was more than sufficient for achieving stringent detection limits in the primitive diagnosis of uracil disorders and fluoropyrimidine toxicity in DPD-deficient patients. The proposed method permits the assessment of Ura and 5FU plasma concentrations with detection limits pf 0.0245 and 0.0484 ng mL(-1) (RSD = 1.0-2.5%, S/N = 3), respectively, without any problems of non-specific false-positives and cross-reactivities in complicated matrices of biological samples.

Development of an Analytical Protocol for Forensic Identification of Chemical Warfare Agent Surrogates

An analytical protocol for forensic identification of chemical warfare agent surrogates in various sample media is developed. This protocol can be implemented on site or in a mobile laboratory, based on a quick sample extraction procedure and a subsequent gas chromatography/mass spectrometry (GC/MS) analysis. The surrogates in this work include 2-chloroethyl ethyl sulfide (CEES), dimethyl methyl phosphonate (DMMP), 2-(butylamino) ethanethiol (BAET), pinacolyl methyl phosphonate (PMP), and diethyl phosphoramidate (DEPA) that are simulants of mustard gas, sarin, VX (O-Ethyl S-2-diisopropylaminoethyl methylphosphonothiolate), soman, and tabun, respectively. The target analytes in headspace or air sample are sampled by the solid phase microextraction (SPME) fibers and all surrogates are easily detected by GC/MS analysis. The neat vapor is also directly analyzed by a portable MS through a membrane inlet but only the more volatile CEES and DMMP are detectable and correctly identified. The stability of surrogates in acetone is monitored in the preparation of standard solution. All surrogates are relatively stable in acetone with the exception of BAET, which is found to degrade quickly in water and other organic solvents (e.g., acetone, methanol, ethanol, hexane). Extraction of water and soil samples is also investigated in this study. In analyzing water sample spiked with the surrogates, it is found that SPME does not offer any advantage over direct aqueous injection into the GC/MS. CEES readily hydrolyzes in water to form 2-(ethylthio)-ethanol. Soil samples are extracted by acetone and the raw extracts are analyzed without any concentration, and all surrogates are detectable at 5–10 ppm level for CEES, DMMP, and DEPA. An actual case study is carried out using SPME to detect the presence of surrogate vapor inside a laboratory refrigerator in which they are stored.

Hollow fiber-based liquid phase microextraction combined with high-performance liquid chromatography for extraction and determination of some antidepressant drugs in biological fluids

The applicability of hollow fiber-based liquid phase microextraction (HF-LPME) was evaluated for the extraction and preconcentration of three antidepressant drugs (amitriptyline, imipramine and sertraline) prior to their determination by HPLC-UV. The target drugs were extracted from 11.0 mL of aqueous solution with pH 12.0 (source phase) into an organic extracting solvent ( n-dodecane) impregnated in the pores of a hollow fiber and finally back extracted into 24 μL of aqueous solution located inside the lumen of the hollow fiber and adjusted to pH 2.1 using 0.1 M of H 3PO 4 (receiving phase). The extraction was performed due to pH gradient between the inside and outside of the hollow fiber membrane. In order to obtain high extraction efficiency, the parameters affecting the HF-LPME including pH of the source and receiving phases, the type of organic phase, ionic strength and volume of the source phase, stirring rate and extraction time were studied and optimized. Under the optimized conditions, enrichment factors up to 300 were achieved and the relative standard deviation (R.S.D.%) of the method was in the range of 2–12%. The calibration curves were obtained in the range of 5–500 μg L −1 with reasonable linearity ( R 2 > 0.998) and the limits of detection (LODs) ranged between 0.5 and 0.7 μg L −1 (based on S/N = 3). Finally, the applicability of the proposed method was evaluated by extraction and determination of the drugs in urine, plasma and tap water samples. The results indicated that hollow fiber microextraction method has excellent clean-up and high-preconcentration factor and can be served as a simple and sensitive method for monitoring of antidepressant drugs in the biological samples.

Screening Method for the Determination at Parts Per Trillion Levels of Pesticide Residues in Vegetables Combining Solid‐Phase Microextraction and Gas Chromatography‐Tandem Mass Spectrometry

A new analytical method is proposed for determining residues of 70 pesticides of different chemical families at parts per trillion levels in fresh vegetables. For that, only 4 g of the vegetable samples were quickly extracted with 10 ml of ethyl acetate. The method is based on a vanguard/rearguard strategy that reduces the average time required per sample when the method is applied to a high number of vegetable samples in a quality control laboratory. At the beginning, an aliquot of the extract is evaporated and re‐dissolved in a mixture water:acetone (9∶1 v/v). For screening purposes, the pesticides were extracted for only 10 min by direct immersion of a solid‐phase microextraction (SPME) fiber (65 µm polydimethylsiloxane‐divinylbenzene, PDMS‐DVB). The SPME device was automated and on‐line coupled to a gas chromatograph with an ion trap mass spectrometer (GC‐MS) operated in full scan mode for screening in less than 18 min those samples that potentially contain pesticides above 0.01 mg kg−1 (cut off value). After that, only those potentially non‐negative samples were reanalyzed by a sensitive quantifying/confirming method that re‐extract by SPME the pesticides in 55 min of absorption and determine them by GC with tandem MS (MS/MS). The method has been validated following EU guidelines and compared with a conventional extraction method based on the use of higher amounts of organic solvents. The limits of detection (LOD), confirmation (LOC) and quantitation (LOQ) as well as the calibration curves obtained allowed the determination of the target pesticides at concentrations clearly below the maximum residue levels (MRL) stated by EU being possible the determination of parts per trillion of the pesticides in ecological (green) vegetables. The method has been applied to the analysis of real samples and the results compared with those obtained by a conventional extraction method accredited by ENAC (Spanish Accreditation Body). The proposed method was also evaluated participating in a proficiency test with adequate results (z‐score among±2).

Preparation and Characterization of Prometryn Molecularly Imprinted Solid‐Phase Microextraction Fibers

A novel reproducible solid‐phase microextraction (SPME) coating was prepared on the surface of silanized silica fibers by molecularly imprinted polymerization using prometryn as template molecule. The structure and extraction performance of molecularly imprinted polymer (MIP) coating was studied with the scanning electron microscope and high performance liquid chromatography (HPLC). Specific selectivity was found with the prometryn MIP‐coated fiber to prometry and its structural analogues such as atrazine, simetryn, terbutylazin, ametryn, propazine and terbutryn. In contrast, these triazines could not be selectively extracted by the non‐imprinted polymer fiber or commercial polydimethylsiloxane (PDMS), polydimethylsiloxane/divinylbenzene (PDMS/DVB), polyacrylate (PA) fibers.

Gas Chromatographic Analysis of Organic Marker Compounds in Fine Particulate Matter Using Solid-Phase Microextraction

A gas chromatographic method that uses solid-phase microextraction for analysis of organic marker compounds in fine particulate matter (PM2.5) is reported. The target marker compounds were selected for specificity toward emission from wood smoke, diesel or gasoline combustion, or meat cooking. Temperature-programmed volatilization analysis was used to characterize the thermal stabilities and volatile properties of the compounds of interest. The compounds were thermally evaporated from a quartz filter, sorbed to a solid phase microextraction (SPME) fiber, and thermally desorbed at 280 °C in a gas chromatograph injection port connected via a DB 1701 capillary separating column. Various experimental parameters (fiber type, time, and temperature of sorption) were optimized. It was found that high extraction yield could be achieved using a polyacrylate fiber for polar substances, such as levoglucosan, and a 7-µm polydimethylsiloxane (PDMS)-coated fiber for nonpolar compounds, such as hopanes and polyaromatic hydrocarbon. A compromise was made by selecting a carboxen/PDMS fiber, which can simultaneously extract all of the analytes of interest with moderate-to-high efficiency at 180 °C within a 30-min accumulation period. The optimized method was applied to the determination of levoglucosan in pine wood combustion emissions. The simplicity, rapidity, and selectivity of sample collection with a polymer-coated SPME coupled to capillary gas chromatography (GC) made this method potentially useful for atmospheric chemistry studies.