Detection of monohydroxylated polycyclic aromatic hydrocarbons in urine and particulate matter using LC separations coupled with integrated SPE and fluorescence detection or coupled with high‐resolution time‐of‐flight mass spectrometry

A high‐performance liquid chromatographic (HPLC) method with integrated solid‐phase extraction for the determination of 1‐hydroxypyrene and 1‐, 2‐, 3‐, 4‐ and 9‐hydroxyphenanthrene in urine was developed and validated. After enzymatic treatment and centrifugation of 500 μL urine, 100 μL of the sample was directly injected into the HPLC system. Integrated solid‐phase extraction was performed on a selective, copper phthalocyanine modified packing material. Subsequent chromatographic separation was achieved on a pentafluorophenyl core–shell column using a methanol gradient. For quantification, time‐programmed fluorescence detection was used. Matrix‐dependent recoveries were between 94.8 and 102.4%, repeatability and reproducibility ranged from 2.2 to 17.9% and detection limits lay between 2.6 and 13.6 ng/L urine. A set of 16 samples from normally exposed adults was analyzed using this HPLC‐fluorescence detection method. Results were comparable with those reported in other studies. The chromatographic separation of the method was transferred to an ultra‐high‐performance liquid chromatography pentafluorophenyl core–shell column and coupled to a high‐resolution time‐of‐flight mass spectrometer (HR‐TOF‐MS). The resulting method was used to demonstrate the applicability of LC‐HR‐TOF‐MS for simultaneous target and suspect screening of monohydroxylated polycyclic aromatic hydrocarbons in extracts of urine and particulate matter.     

Optimization of microwave-assisted extraction of hydrocarbons in marine sediments: comparison with the Soxhlet extraction method

Microwave energy was applied to extract polycyclic aromatic hydrocarbons (PAHs) and linear aliphatic hydrocarbons (LAHs) from marine sediments. The influence of experimental conditions, such as different extracting solvents and mixtures, microwave power, irradiation time and number of samples extracted per run has been tested using real marine sediment samples; volume of the solvent, sample quantity and matrix effects were also evaluated. The yield of extracted compounds obtained by microwave irradiation was compared with that obtained using the traditional Soxhlet extraction. The best results were achieved with a mixture of acetone and hexane (1:1), and recoveries ranged from 92 to 106%. The extraction time is dependent on the irradiation power and the number of samples extracted per run, so when the irradiation power was set to 500 W, the extraction times varied from 6 min for 1 sample to 18 min for 8 samples. Analytical determinations were carried out by high-performance liquid chromatography (HPLC) with an ultraviolet-visible photodiode-array detector for PAHs and gas chromatography (GC) using a FID detector for LAHs. To test the accuracy of the microwave-assisted extraction (MAE) technique, optimized methodology was applied to the analysis of standard reference material (SRM 1941), obtaining acceptable results.     

Optimization of microwave-assisted extraction of hydrocarbons in marine sediments: comparison with the Soxhlet extraction method

Microwave energy was applied to extract polycyclic aromatic hydrocarbons (PAHs) and linear aliphatic hydrocarbons (LAHs) from marine sediments. The influence of experimental conditions, such as different extracting solvents and mixtures, microwave power, irradiation time and number of samples extracted per run has been tested using real marine sediment samples; volume of the solvent, sample quantity and matrix effects were also evaluated. The yield of extracted compounds obtained by microwave irradiation was compared with that obtained using the traditional Soxhlet extraction. The best results were achieved with a mixture of acetone and hexane ¶(1?:?1), and recoveries ranged from 92 to 106%. The extraction time is dependent on the irradiation power and the number of samples extracted per run, so when the irradiation power was set to 500 W, the extraction times varied from 6 min for 1 sample to 18 min for 8 samples. Analytical determinations were carried out by high-performance liquid chromatography (HPLC) with an ultraviolet-visible photodiode-array detector for PAHs and gas chromatography (GC) using a FID detector for LAHs. To test the accuracy of the microwave-assisted extraction (MAE) technique, optimized methodology was applied to the analysis of standard reference material (SRM 1941), obtaining acceptable results.     

Validated UHPLC–MS/MS assay for quantitative determination of etoposide,gemcitabine, vinorelbine and their metabolites in patients with lung cancer

A fully valid UHPLC–MS/MS method was developed for the determination of etoposide, gemcitabine, vinorelbine and their metabolites (etoposide catechol, 2′,2′‐difluorodeoxyuridine and 4‐O ‐deacetylvinorelbine) in human plasma. The multiple reaction monitoring mode was performed with an electrospray ionization interface operating in both the positive and negative ion modes per compound. The method required only 100 μL plasma with a one‐step simple de‐proteinization procedure, and a short run time of 7.5 min per sample. A Waters ACQUITY UPLC HSS T3 column (2.1 × 100 mm, 1.8 μm) provided chromatographic separation of analytes using a binary mobile phase gradient (A, 0.1% formic acid in acetonitrile, v /v; B, 0.1% formic acid in water, v /v). Linear coefficients of correlation were >0.995 for all analytes. The relative deviation of this method was <10% for intra‐ and inter‐day assays and the accuracy ranged between 86.35% and 113.44%. The mean extraction recovery and matrix effect of all the analytes were 62.07–105.46% and 93.67–105.87%, respectively. This method was successfully applied to clinical samples from patients with lung cancer.     

Development, validation and transfer of a hydrophilic interaction liquid chromatography/tandem mass spectrometric method for the analysis of the tobacco-specific nitrosamine metabolite NNAL in human plasma at low picogram per milliliter concentrations

A highly sensitive bioanalytical method based on a simple liquid/liquid extraction and hydrophilic interaction liquid chromatography with tandem mass spectrometry (HILIC/MS/MS) analysis has been developed, validated and transferred for the determination of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), a tobacco-specific nitrosamine metabolite. Deuterated NNAL (NNAL-d(4)) was synthesized and used as the internal standard. This method can be used for the analysis of free and total NNAL (free NNAL plus NNAL-gluc) in K(3)-EDTA human plasma. Free NNAL and NNAL-d(4) are extracted from human plasma by liquid/liquid extraction. To analyze for total NNAL and the internal standard, a separate aliquot of the K(3)-EDTA human plasma is treated with beta-glucuronidase to deconjugate the NNAL-gluc; the total NNAL and internal standard are then extracted using liquid/liquid extraction. After drying down under nitrogen, the residue is reconstituted with acetonitrile and analyzed using positive ion electrospray and HILIC/MS/MS at a flow rate of 1.0 mL/min. The chromatographic run time is 1.0 min per injection, with retention time for both NNAL and NNAL-d(4) of 0.75 min with a capacity factor (k') of 2. The standard curve range for this assay is from 5.00-1000 pg/mL for both free and total NNAL, using a total plasma sample volume of 1.0 mL. The interday precision and accuracy of the quality control (QC) samples demonstrated <7.6% relative standard deviation (RSD) and <3.3% relative error (RE) for free NNAL. For total NNAL, the interday precision and accuracy of the QC samples demonstrated <11.7% RSD and <2.8% RE. Optimization of enzyme hydrolysis of NNAL-gluc is discussed in detail. The overall recoveries for free and total NNAL and IS were 68.2 and 71.5% (free) and 70.7 and 65.5% (total). No adverse matrix effects were noticed for this assay.     

Fast and comprehensive analysis of secondary metabolites in cocoa products using ultra high‐performance liquid chromatography directly after pressurized liquid extraction

Fast methods for the extraction and analysis of various secondary metabolites from cocoa products were developed and optimized regarding speed and separation efficiency. Extraction by pressurized liquid extraction is automated and the extracts are analyzed by rapid reversed‐phase ultra high‐performance liquid chromatography and normal‐phase high‐performance liquid chromatography methods. After extraction, no further sample treatment is required before chromatographic analysis. The analytes comprise monomeric and oligomeric flavanols, flavonols, methylxanthins, N‐phenylpropenoyl amino acids, and phenolic acids. Polyphenols and N‐phenylpropenoyl amino acids are separated in a single run of 33 min, procyanidins are analyzed by normal‐phase high‐performance liquid chromatography within 16 min, and methylxanthins require only 6 min total run time. A fourth method is suitable for phenolic acids, but only protocatechuic acid was found in relevant quantities. The optimized methods were validated and applied to 27 dark chocolates, one milk chocolate, two cocoa powders and two food supplements based on cocoa extract.     

Optimization of pressurized liquid extraction and purification conditions for gas chromatography-mass spectrometry determination of UV filters in sludge

This work presents an effective sample preparation method for the determination of eight UV filter compounds, belonging to different chemical classes, in freeze-dried sludge samples. Pressurized liquid extraction (PLE) and gas chromatography-mass spectrometry (GC-MS) were selected as extraction and determination techniques, respectively. Normal-phase, reversed-phase and anionic exchange materials were tested as clean-up sorbents to reduce the complexity of raw PLE extracts. Under final working conditions, graphitized carbon (0.5 g) was used as in-cell purification sorbent for the retention of co-extracted pigments. Thereafter, a solid-phase extraction cartridge, containing 0.5 g of primary secondary amine (PSA) bonded silica, was employed for off-line removal of other interferences, mainly fatty acids, overlapping the chromatographic peaks of some UV filters. Extractions were performed with a n-hexane:dichloromethane (80:20, v:v) solution at 75°C, using a single extraction cycle of 5 min at 1500 psi. Flush volume and purge time were set at 100% and 2 min, respectively. Considering 0.5 g of sample and 1 mL as the final volume of the purified extract, the developed method provided recoveries between 73% and 112%, with limits of quantification (LOQs) from 17 to 61 ng g(-1) and a linear response range up to 10 μg g(-1). Total solvent consumption remained around 30 mL per sample. The analysis of non-spiked samples confirmed the sorption of significant amounts of several UV filters in sludge with average concentrations above 0.6 μg g(-1) for 3-(4-methylbenzylidene) camphor (4-MBC), 2-ethylhexyl-p-methoxycinnamate (EHMC) and octocrylene (OC).     

Optimized and validated high‐performance liquid chromatography method for the determination of deoxynivalenol and aflatoxins in cereals

A simple, sensitive and accurate analytical method was optimized and developed for the determination of deoxynivalenol and aflatoxins in cereals intended for human consumption using high‐performance liquid chromatography with diode array and fluorescence detection and a photochemical reactor for enhanced detection. A response surface methodology, using a fractional central composite design, was carried out for optimization of the water percentage at the beginning of the run (X1, 80–90%), the level of acetonitrile at the end of gradient system (X2, 10–20%) with the water percentage fixed at 60%, and the flow rate (X3, 0.8–1.2 mL/min). The studied responses were the chromatographic peak area, the resolution factor and the time of analysis. Optimal chromatographic conditions were: X1 = 80%, X2 = 10%, and X3 = 1 mL/min. Following a double sample extraction with water and a mixture of methanol/water, mycotoxins were rapidly purified by an optimized solid‐phase extraction protocol. The optimized method was further validated with respect to linearity (R²>0.9991), sensitivity, precision, and recovery (90–112%). The application to 23 commercial cereal samples from Greece showed contamination levels below the legally set limits, except for one maize sample. The main advantages of the developed method are the simplicity of operation and the low cost.     

Liquid chromatography–mass spectrometry methods for urinary biomarker detection in metabonomic studies with application to nutritional studies

The effects of sample preparation and chromatographic method differences on the classification and recovery of metabolic biomarkers from UPLC‐MS measurements on urine samples of humans exposed to different dietary interventions have been investigated. Eight volunteers consumed three high‐fat meals (rich in saturated, monounsaturated and polyunsaturated fatty acids, respectively) in randomized order with a washout period in between. For each participant, urine samples were obtained prior to and at three timed intervals after each meal. Samples were processed either by dilution (1 : 4) or by liquid–liquid extraction and then run under two different gradient conditions. For each analysis method, a total of 96 observations (eight participants, four time points, three diets) were measured. The total ion count chromatograms were analyzed using partial‐least‐squares discriminant analysis. All three dietary classes could be discriminated irrespective of sample preparation and chromatographic method. However, the main discriminating metabolites varied according to sample preparation, indicating that sample treatment and chromatographic conditions influence the ability to extract biomolecular information. Diluted samples showed higher m/z compounds (ca 400 u) while liquid–liquid extraction samples showed low m/z at the same retention time span. Optimized methods for metabolite identification (e.g. organic acids) were statistically inferior to global screening for mixed compound identification, confirming that multiple compound class‐based metabolic profiles are likely to give superior metabonomic (diagnostic) classification, although great care has to be taken in the interpretation in relation to matrix effects. Copyright © 2009 John Wiley & Sons, Ltd.     

Development and validation of amitriptyline and its metabolite in human plasma by ultra performance liquid chromatography-tandem mass spectrometry and its application to a bioequivalence study

A method based on ultra performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS) in combination with solid‐phase extraction for sample pretreatment has been developed for the simultaneous analysis of amitriptyline and its main metabolite in human plasma. The extraction of the analytes from plasma samples was carried out by means of a selective SPE procedure using hydrophilic–lipophilic balance cartridges. The assay involves a simple solid‐phase extraction (SPE) procedure of 0.2 mL of human plasma and analysis was performed on a triple‐quadrupole tandem mass spectrometer by multiple reactions monitoring (MRM) mode via electrospray ionization (ESI). The standard calibration curve was linear over the ranges 0.370–95.539 ng/mL for amitriptyline and 0.365–94.374 ng/mL for nortriptyline, expressed by the linear correlation coefficient r², which was better than 0.995 for both. The intra‐ and inter‐day precision and accuracy of the quality control samples were within 10.0%. The recovery was 85.3, 88.4 and 80.7% for amitriptyline, nortriptyline and doxepin respectively. Total run time was 1.2 min only for each sample, which makes it possible to analyze more than 400 samples per day. The method was highly reproducible and gave peaks with excellent chromatography properties. Copyright © 2010 John Wiley & Sons, Ltd.     

Simultaneous extraction and preconcentration of aniline,phenol, and naphthalene using magnetite–graphene oxide composites before gas chromatography determination

The coextraction of acidic and basic compounds from different mediums is a significant concept in sample preparation. In this work, simultaneous extraction of acidic, basic, and neutral analytes in a single step was carried out for the first time. This procedure employed the dispersive solid‐phase microextraction of analytes with magnetic graphene oxide (graphene oxide/Fe₃O₄) sorbent followed by gas chromatography with flame ionization detection. After the adsorption of analytes by vortexing and decantation of the supernatant with a magnet, the sorbent was eluted with acetonitrile/methanol (2:1) mixture. The parameters affecting the extraction efficiency were optimized and obtained as follows: sorbent amount 60 mg, desorption time 1 min, extraction time 5 min, pH of the sample 7, sample volume 20 mL, and elution solvent volume 0.3 mL. Under the optimum conditions, linear dynamic ranges were achieved in the range of 0.5–4, 0.25–4, and 0.25–2 μg/mL and limits of detection were 0.341, 0.110, and 0.167 μg/mL for aniline, phenol, and naphthalene, respectively. The relative standard deviations were in the range of 3.3–5.7% in eight repeated extractions. Finally, the applicability of the method was evaluated by the extraction and determination of analytes in stream water and drinking water samples and satisfactory results were obtained.     

A rapid and sensitive LC‐MS/MS method for the determination of linarin in small‐volume rat plasma and tissue samples and its application to pharmacokinetic and tissue distribution study

A rapid and sensitive LC‐MS/MS method was developed for the determination of linarin in small‐volume rat plasma and tissue sample. Sample preparation was employed by the combination of protein precipitation (PPT) and liquid–liquid extraction (LLE) to allow measurement over a 5‐order‐of‐magnitude concentration range. Fast chromatographic separation was achieved on a Hypersil Gold column (100 × 2.1 mm i.d., 5 µm). Mass spectrometric detection was achieved using a triple‐quadrupole mass spectrometer equipped with an electrospray ionization interface operating in positive ionization mode. Quantification was performed using selected reaction monitoring of precursor‐product ion transitions at m/z 593 → 285 for linarin and m/z 447 → 271 for baicalin (internal standard). The total run time was only 2.8 min per sample. The calibration curves were linear over the concentration range of 0.4–200 µg/mL for PPT and 0.001–1.0 µg/mL for LLE. A lower limit of quantification of 1.0 ng/mL was achieved using only 20 μL of plasma or tissue homogenate. The intra‐ and inter‐day precisions in all samples were ≤14.7%, while the accuracy was within ±5.2% of nominal values. The validated method has been successfully applied to pharmacokinetic and tissue distribution study of linarin. Copyright © 2015 John Wiley & Sons, Ltd.     

Simultaneous quantification of fentanyl,sufentanil, cefazolin,doxapram and keto‐doxapram in plasma using liquid chromatography–tandem mass spectrometry

A simple and specific UPLC–MS/MS method was developed and validated for simultaneous quantification of fentanyl, sufentanil, cefazolin, doxapram and its active metabolite keto‐doxapram. The internal standard was fentanyl‐d5 for all analytes. Chromatographic separation was achieved with a reversed‐phase Acquity UPLC HSS T3 column with a run‐time of only 5.0 min per injected sample. Gradient elution was performed with a mobile phase consisting of ammonium acetate or formic acid in Milli‐Q ultrapure water or in methanol with a total flow rate of 0.4 mL min⁻¹. A plasma volume of only 50 μL was required to achieve adequate accuracy and precision. Calibration curves of all five analytes were linear. All analytes were stable for at least 48 h in the autosampler. The method was validated according to US Food and Drug Administration guidelines. This method allows quantification of fentanyl, sufentanil, cefazolin, doxapram and keto‐doxapram, which is useful for research as well as therapeutic drug monitoring, if applicable. The strength of this method is the combination of a small sample volume, a short run‐time, a deuterated internal standard, an easy sample preparation method and the ability to simultaneously quantify all analytes in one run.     

Optimization via experimental design of an SPE-HPLC-UV-fluorescence method for the determination of valsartan and its metabolite in human plasma samples

A chemometric approach was applied for the optimization of the extraction and separation of the antihypertensive drug valsartan and its metabolite valeryl-4-hydroxy-valsartan from human plasma samples. Due to the high number of experimental and response variables to be studied, fractional factorial design (FFD) and central composite design (CCD) were used to optimize the HPLC-UV-fluorescence method. First, the significant variables were chosen with the help of FFD; then, a CCD was run to obtain the optimal values for the significant variables. The measured responses were the corrected areas of the two analytes and the resolution between the chromatographic peaks. Separation of valsartan, its metabolite valeryl-4-hydroxy-valsartan and candesartan M1, used as internal standard, was made using an Atlantis dC18 100 mm x 3.9 mm id, 100 angstroms, 3 microm chromatographic column. The mobile phase was run in gradient elution mode and consisted of ACN with 0.025% TFA and a 5 mM phosphate buffer with 0.025% TFA at pH 2.5. The initial percentage of ACN was 32% with a stepness of 4.5%/min to reach the 50%. A flow rate of 1.30 mL/min was applied throughout the chromatographic run, and the column temperature was kept to 40+/-0.2 degrees C. In the SPE procedure, experimental design was also used in order at achieve a maximum recovery percentage and extracts free from plasma interferences. The extraction procedure for spiked human plasma samples was carried out using C8 cartridges, phosphate buffer (pH 2, 60 mM) as conditioning agent, a washing step with methanol-phosphate buffer (40:60 v/v), a drying step of 8 min, and diethyl ether as eluent. The SPE-HPLC-UV-fluorescence method developed allowed the separation and quantitation of valsartan and its metabolite from human plasma samples with an adequate resolution and a total analysis time of 1 h.     

Partial least squares model and design of experiments toward the analysis of the metabolome of Jatropha gossypifolia leaves: Extraction and chromatographic fingerprint optimization

A major challenge in metabolomic studies is how to extract and analyze an entire metabolome. So far, no single method was able to clearly complete this task in an efficient and reproducible way. In this work we proposed a sequential strategy for the extraction and chromatographic separation of metabolites from leaves Jatropha gossypifolia using a design of experiments and partial least square model. The effect of 14 different solvents on extraction process was evaluated and an optimized separation condition on liquid chromatography was estimated considering mobile phase composition and analysis time. The initial conditions of extraction using methanol and separation in 30 min between 5 and 100% water/methanol (1:1 v/v) with 0.1% of acetic acid, 20 μL sample volume, 3.0 mL min^?1 flow rate and 25°C column temperature led to 107 chromatographic peaks. After the optimization strategy using i‐propanol/chloroform (1:1 v/v) for extraction, linear gradient elution of 60 min between 5 and 100% water/(acetonitrile/methanol 68:32 v/v with 0.1% of acetic acid), 30 μL sample volume, 2.0 mL min^?1 flow rate, and 30°C column temperature, we detected 140 chromatographic peaks, 30.84% more peaks compared to initial method. This is a reliable strategy using a limited number of experiments for metabolomics protocols.     

Rapid analysis of ranitidine in biological fluids and determination of its erythrocyte partitioning

A reversed-phase ion-pair high-performance liquid chromatographic assay is described for the rapid and sensitive quantitation of the H2-receptor antagonist ranitidine in human plasma and urine. The method involves a single-step extraction of the alkalinized sample with methylene chloride and analysis of the evaporated extract on a cyano column. Detection was performed by ultraviolet absorbance monitored at 318 nm. The overall run time of the assay was 5 min at a flow-rate of 2.0 ml/min. The limit of sensitivity was 1 ng/ml ranitidine in human plasma. Urine and plasma samples collected from a subject after administration of an oral dose of 150 mg of ranitidine were analyzed by this method. Furthermore, the procedure was applied to determine the red blood cell partition coefficient of ranitidine in a concentration range up to 10 micrograms/ml.     

A novel LC-MS/MS method for simultaneous quantification of tenofovir and lamivudine in human plasma and its application to a pharmacokinetic study

A new, rapid, sensitive and specific LC‐MS/MS method has been developed and validated for the simultaneous quantification of tenofovir and lamivudine in human plasma using abacavir as an internal standard. An API‐4000 LC‐MS/MS with electrospray ionization was operated in multiple‐reaction monitoring mode for the analysis. The analytes were extracted from plasma by solid‐phase extraction technique using an Oasis HLB cartridge. The reconstituted samples were chromatographed on a Chromolith ROD speed C₁₈ column using a mixture of 0.1% formic acid in water and acetonitrile (90:10 v/v) at a flow‐rate of 1 mL/min. The method was validated as per the FDA guidelines. The calibration curves were found to be linear in the range of 5–600 ng/mL for tenofovir and 25– 4000 ng/mL for lamivudine. The intra‐ and inter‐day precision and accuracy results were well within the acceptable limits. A run time of 2.8 min consumed for each sample made it possible to analyze more samples per day. The proposed assay method was found to be applicable to a pharmacokinetic study in human male volunteers. Copyright © 2012 John Wiley & Sons, Ltd.     

Quantitative gas-liquid chromatography of neutral sugars in human serum glycoproteins. Fucose, mannose, and galactose as predictors in ovarian and small cell lung carcinoma

A precise and accurate gas-liquid chromatographic (GLC) method has been developed for the quantitative analysis of the neutral sugars L-fucose (6-deoxygalactose), mannose, galactose, and glucose in ethanol precipitates of human serum proteins. The chromatographic conditions and sample preparation resulted in short analysis time (20 min per run) and made routine analyses practicable (twelve samples per day). The alditol acetate derivatization yielded single derivatives for each sugar. Complete separation was achieved on a 2.0 m X 2 mm I.D. column with 2.0% Silar-7CP on Chromosorb W AW 80--100 mesh. The results of hydrolysis showed that the release of fucose and galactose preceded the release of mannose. Hydrolysis with AG 50 W-X8 (H+) ion-exchange resin in 0.5 N HCl at 100 degrees for 7 h optimized glycosidic bond cleavage with only minimal destruction of fucose, mannose and galactose. A combination of strong cation- and anion-exchange resin columns was used to remove chromatographic background of peptides, amino acids, amino sugars, and inorganic ions. An average R.S.D. of less than 4% with recovery of greater than 86% for the three sugars was achieved. The homogeneity of the chromatographic peaks for the neutral sugars of normal human serum glycoproteins was confirmed by GLC--mass spectrometry. Significantly elevated ratios of fucose, galactose, and mannose to serum protein were observed for patients with small cell lung and ovarian carcinomas.     

Analysis of semi-volatile organic compounds in aqueous samples by microwave-assisted headspace solid-phase microextraction coupled with gas chromatography-electron capture detection

The pretreatment technique of microwave-assisted headspace solid-phase microextraction (MA-HS-SPME) has been developed and studied for the extraction of semi-volatile organic compounds (SVOCs) in aqueous samples prior to chromatographic analysis. The optimum conditions for obtaining extraction efficiency, such as the extraction time, extraction temperature, addition of salts, and the ratio of sample to headspace volume parameters were investigated. Experimental results indicated that the proposed MA-HS-SPME technique attained the best extraction efficiency under the optimized conditions, i.e., irradiation of extraction solution (20mL aqueous sample in 40mL headspace vial with no addition of salt) under 30W microwave power for 30min at 70 degrees C. The detection was linear at 1-250ng/L with correlation coefficient exceeding 0.997. The detection limits obtained were between 0.2-10.7ng/L, repeatability range from 2 to 15%. Real water samples collected from known sites in southern Taiwan were analyzed using the optimized conditions.