Determination of phthalate esters in water samples by solid-phase microextraction and gas chromatography with mass spectrometric detection

Solid-phase microextraction (SPME) with an 85 microm polyacrylate fiber, coupled to gas chromatography-mass spectrometry was used to determine six phthalate esters and bis(2-ethylhexyl) adipate in water samples. The variables affecting the SPME absorption process were optimized and the method developed was applied to analyze both tap and commercial mineral water samples as well as water from the Ebro river and fishing and industrial ports. For real samples, the linear range in full scan acquisition mode was between 0.02 and 10 microg l(-1) for most compounds, and the limits of detection of the method were between 0.006 and 0.17 microg l(-1). Commercial water samples contained in recipients which were made from different materials were analyzed, and the influence of the material of the recipients on the concentration of phthalates was evaluated.     

Determination of organochlorine pesticides in ground water using solid-phase microextraction followed by dual-column gas chromatography with electron-capture detection

A rapid, sensitive, convenient, and highly quality-assured method is presented for the determination of 19 organochlorine pesticides (OCPs) in small samples (10 ml) of ground water. Samples are initially fortified with 2,4,5,6-tetrachloro-m-xylene (surrogate) and decachlorobiphenyl (retention time marker), then extracted with a 30-micron thickness polydimethylsiloxane solid-phase microextraction fiber. The analytes collected are thermally desorbed in a heated gas chromatographic inlet, separated using independent fused-silica capillary columns ("primary" and "confirmatory"), and detected using electron-capture detection. Two independent statistical procedures were used to evaluate the detection limits, which typically range between 10 and 40 ng l-1, for these analytes. Method performance was also evaluated using two additional protocols employing "performance evaluation" samples, in which authentic ground water samples were fortified to ca. 100 ng l-1 in each of at least six OCPs. The method satisfies additional strict criteria based on uniformity of fiber performance and minimal degradation of the thermally-sensitive analytes endrin and DDT.     

Determination of lewisite oxide in soil using solid-phase microextraction followed by gas chromatography with flame photometric or mass spectrometric detection

A rapid, sensitive, and convenient method is described for determining Lewisite oxide in soil. Samples are initially fortified with phenylarsine oxide (surrogate), then both species are extracted using ascorbic acid solutions containing 1,3-propanedithiol (derivatizing reagent). The corresponding filtered supernatant is sampled using a solid-phase microextraction fiber. Collected analytes are thermally desorbed in a heated gas chromatographic inlet, separated using fused-silica capillary columns ("primary" and "confirmatory"), and detected with either a mass spectrometric (selected ion monitoring mode) or flame photometric (sulfur-selective mode) detector. Two independent statistically-unbiased procedures were used to evaluate the detection limit for Lewisite oxide; the values range between 0.1 and 0.5 microg g(-1) soil.     

Pesticide trace analysis using solid-phase extraction and gas chromatography with electron-capture and tandem mass spectrometric detection in water samples

Gas chromatography (GC) with electron-capture detection (ECD), mass spectrometry (MS) and tandem mass spectrometry (MS-MS) were employed for the identification of 12 pesticides in water samples. For this purpose, a solid-phase extraction procedure with C18 cartridges was used, optimising the breakthrough volume and the saturation concentration. In GC-MS-MS, the lowest detectable concentrations for the pesticides were between 2 and 26 ng l(-1), recoveries ranged from 70 to 133% in water samples spiked at 100 ng l(-1) and the relative standard deviations were in the range 5.3 to 17.4%. The proposed analytical methodology was applied to analyse pesticides in wetland samples from Almería (Spain).     

Determination of phthalates in water samples using polyaniline-based solid-phase microextraction coupled with gas chromatography

A simple solid-phase microextraction (SPME) device, coupled with gas chromatography-flame ionization detection (GC-FID), was developed to detect trace levels of phthalates in environmental water samples. Polyaniline (PANI) was chosen as the sorbent for the SPME device and was electrochemically deposited on a stainless steel wire to achieve high thermal and mechanical stability. The porous structure of the PANI film, characterized by scanning electron microscopy (SEM), suggested large extraction capability. Key parameters were optimized and five phthalates were selected to evaluate the SPME-GC procedures. The method was also applied to the analysis of lake and river water samples. Control experiments were carried out using commercial polyacrylate (PA) fiber. The new PANI-SPME-GC method offers high accuracy, precision and sensitivity and low detection limits. Thus, the method developed could be used as a new way to monitor the trace levels of phthalates in water medium. A possible extraction mechanism was investigated using electrochemical impedance spectroscopy (EIS).     

Simple determination of 22 organophosphorous pesticides in human blood using headspace solid-phase microextraction and gas chromatography with mass spectrometric detection

A simple and rapid procedure for the determination of 22 organophosphorous pesticides (bromophos-ethyl, bromophos-methyl, chlorfenvinphos, chlorpyriphos, demethon-S-methylsulfon, diazinon, dichlorvos, dicrotophos, dimethoate, disulfoton, edifenphos, fenitrothion, fenthion, malathion, methidathion, mevinphos, monocrotophos, omethoate, parathion-ethyl, parathion-methyl, phosphamidon, and quinalphos) in human blood using headspace (HS) solid-phase microextraction (SPME) and gas chromatography (GC)-mass spectrometry (MS) is presented. The effects of various sample additions, incubation temperatures, absorption times, desorption times, and depths of fiber insertion into the injection port of the GC are optimized to enhance the sensitivity of the procedure. The recoveries of spiked blood samples are determined between 70% and 95% compared with samples prepared in water, and absolute recoveries are in the range between 0.1% and 19.6%. For quantitation in the single ion monitoring mode, linearity is established over concentration ranges from 0.025 to 5.0 microg/g with excellent coefficients of correlation (0.991-0.998). The detection limits are in the range between 0.01 and 0.3 microg/g. The time for analysis is 44 min per sample including extraction and GC-MS analysis. HS-SPME in combination with GC-MS is an effective method for the determination of organophosphorous pesticides in human blood and shows a great potential for use in rapid on-site analytical work, which is highly demanded in clinical and forensic toxicology.     

Determination of mono- to octachlorobiphenyls in fish oil using florisil adsorption followed by headspace solid-phase microextraction and gas chromatography with time-of-flight mass spectrometric detection

A simple and reliable method for the determination of polychlorinated biphenyls (PCBs) from mono- to octachlorobiphenyls in fish oil for dietary supplement is described. The method combines Florisil clean up and headspace solid-phase microextraction on 65 microm polydimethylsiloxane-divinylbenzene (PDMS-DVB). Analyte detection was carried out using GC-time-of-flight mass spectrometry (GC-TOF-MS). Fifty three PCB congeners including the seven indicator PCBs (IUPAC Nos. 28, 52, 101, 118, 138, 153 and 180) were analyzed. Under optimal conditions, the method detection limit (MDL) of each congener in the range from 0.8 to 31 ng/g was found. A certified reference material (BCR-349) was analyzed and it showed good agreement with the certified data.     

Analysis of virgin olive oil volatile compounds by headspace solid-phase microextraction coupled to gas chromatography with mass spectrometric and flame ionization detection

The efficiency of headspace solid-phase microextraction (SPME) was evaluated for the qualitative and semi-quantitative analysis of virgin olive oil volatile compounds. The behaviour of four fibre coatings was compared for sensitivity, repeatability and linearity of response. A divinylbenzene-Carboxen-polydimethylsiloxane fibre coating was found to be the most suitable for the analysis of virgin olive oil volatiles. Sampling and chromatographic conditions were examined and the SPME method, coupled to GC with MS and flame ionization detection, was applied to virgin olive oil samples. More than 100 compounds were isolated and characterised. The presence of some of these compounds in virgin olive oil has not previously been reported. The main volatile compounds present in the oil samples were determined quantitatively.     

Determination of phosphoric acid triesters in human plasma using solid-phase microextraction and gas chromatography coupled to inductively coupled plasma mass spectrometry

A simple and sensitive method for determination of phosphoric acid triesters at trace levels in human plasma sample is described. In this work, solid-phase microextraction (SPME) is employed as a sample preparation procedure for extraction and pre-concentration of alkyl and aryl phosphates followed by gas chromatography coupled to inductively coupled plasma mass spectrometry (GC-ICP-MS) for phosphorus-specific and very sensitive determination of these compounds in human plasma. The detection limits from blood plasma were 50 ngL(-1) (tripropyl phosphate), 17 ngL(-1) (tributyl phosphate), 240 ngL(-1) (tris(2-chloroethyl) phosphate) and 24 ngL(-1) (triphenyl phosphate). Sample preparation involves plasma deproteinization followed by direct immersion SPME with 65 microm poly(dimethylsiloxane/divinylbenzene) fiber. Extraction was performed at 40 degrees C for 30 min and at pH 7.0 in 10 mM sodium carbonate buffer. The reported method, to our knowledge, describes the first application of SPME with element-specific detection for analysis of phosphoric acid esters. Application of the method to the plasma samples, previously stored in poly(vinyl chloride) plasma bags revealed the presence of triphenyl phosphate, which was further confirmed by SPME GC time-of-flight high-resolution mass spectrometry.     

Determination of phthalate esters in cow milk samples using dispersive liquid-liquid microextraction coupled with gas chromatography followed by flame ionization and mass spectrometric detection

A simple and economic method for the analysis of phthalate esters, dimethyl phthalate, diethyl phthalate, di-iso-butyl phthalate, di-n-butyl phthalate, and di-2-ethylhexyl phthalate in cow milk samples by means of gas chromatography-flame ionization detection and gas chromatography-mass spectrometry has been developed. In this work, NaCl and ACN were added to 5 mL of the milk sample as the salting out agent and extraction solvent, respectively. After manual shaking, the mixture was centrifuged. In the presence of NaCl, a two-phase system was formed: upper phase - acetonitrile containing phthalate esters -and lower phase - aqueous phase containing soluble compounds and the precipitated proteins. After the extraction of phthalate esters from milk, a portion of supernatant phase (acetonitrile) was removed, mixed with 1,2-dibromoethane at microliter level and injected by syringe into NaCl solution. After the extraction of the selected phthalate esters into 1,2-dibromoethane, phase separation was performed by centrifugation and the enriched analytes in the sedimented phase were determined by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry. Under the optimum extraction conditions, low limits of detection and quantification between 1.5-3 and 2.5-11 ng/mL, respectively was observed. Enrichment factors were in the range of 397-499. The relative standard deviations for the extraction of 100 ng/mL of each phthalate ester were in the range of 3-4% (n = 6). Finally, some milk samples were successfully analyzed using the proposed method and two analytes, di-n-butyl phthalate and di-2-ethylhyxel phthalate, were determined in them in nanogram per milliliter level.     

Determination of fungicides in water using liquid phase microextraction and gas chromatography with electron capture detection

A hollow fiber liquid phase microextraction (HF-LPME) and gas chromatographic-electron capture detection (GC-ECD) method for the determination of six fungicides (chlorothalonil, hexaconazole, penconazole, procymidone, tetraconazole, and vinclozolin) in 3 ml of water was described. The method used 3 μl of toluene as extraction solvent, 20 min extraction time with pH 4, stirring at 870 rpm, and no salt addition. The enrichment factors of this method were from 135 to 213. Limits of detection were in the range of 0.004-0.025 μg/l. The relative standard deviations (RSDs) at 0.1 and 5 μg/l of spiking levels were in the range 3-8%. Recoveries of six fungicides from farm water at a spiking level of 0.5 μg/l were between 90.7 and 97.6%. The method compared favorably with the traditional method in terms of the sample size, analysis time, and cost.     

Determination of natural and synthetic estrogens in water by gas chromatography with mass spectrometric detection

A procedure for the determination of six natural and synthetic estrogens (diethylstilbestrol, estrone, 17beta-estradiol, mestranol, 17alpha-ethinylestradiol and estriol) in water samples is described. Samples, up to 2000 ml, were concentrated using Oasis HLB solid-phase extraction cartridges. Analytes were derivatized with N-methyl-N-(trimethylsilyl)trifluoroacetamide and determined by GC-MS or GC-MS-MS. The reactivity of several silylation reagents versus aliphatic and aromatic hydroxyl groups contained in the structure of the selected analytes was evaluated. Influence of parameters such as sample pH, nature of the water samples and derivatization conditions on the performance of the whole analytical procedure was systematically studied. Under optimal conditions, quantification limits between 1 and 3 ng/l were achieved for the determination of the considered estrogens in sewage water.     

Simultaneous determination of "earthy-musty" odorous haloanisoles and their corresponding halophenols in water samples using solid-phase microextraction coupled to gas chromatography with electron-capture detection

Certain haloanisoles present at trace levels cause a large part of earthy-musty off-flavor problems in drinking water. These potent odorous chemicals come mainly through biomethylation of their corresponding halopenols. To enable the investigation of both families of compounds, a method involving solid-phase microextraction (SPME) was developed and the main parameters governing SPME were optimized. This method allows the simultaneous quantification of haloanisoles and halophenols at levels ranging from 1 to 100 or 250 ng/l, with detection limits of about 0.5 ng/l and could be applied to potable as well as raw surface waters.     

Determination of volatile aliphatic amines in air by solid-phase microextraction coupled with gas chromatography with flame ionization detection

Practical aspects of the application of solid-phase microextraction (SPME) to the determination of volatile aliphatic amines in air are described. Analytes included methylamine (MA), ethylamine (EA), dimethylamine (DMA), diethylamine (DEA), trimethylamine (TMA) and triethylamine (TEA). New SPME stationary phases were examined. The effects of relative humidity and temperature on analytes uptake were taken into account in analysis. Gas chromatography (GC) with flame ionization detector (FID) was used for the final analysis.     

管内固相微萃取-气相色谱法联用在线测定水中有机物

将管内固相微萃取与气相色谱法结合，建立了水中痕量有机物的在线分析装置。采用毛细管气相色谱柱作为萃取柱，水样中的分析物在萃取柱中被萃取浓缩，溶剂解吸后的样品通过阀切换和柱内进样技术直接由载气携带进入气相色谱柱。采用OV-1萃取柱，对水样中的5种芳烃的富集倍数为34～85。     

Determination of thiodyglycol in groundwater using solid-phase extraction followed by gas chromatography with mass spectrometric detection in the selected-ion mode

A highly sensitive analytical procedure is described for determining thiodiglycol in groundwater. Samples are initially fortified with 3,3'-thiodipropanol (surrogate), then both species are extracted using sequential solid-phase extraction with both C18 and Ambersorb 572 columns. The C18 column, which removes extraneous groundwater components, is discarded; the Ambersorb 572 column is dried thoroughly before eluting polar components with a small volume of dichloromethane. The extract is taken to dryness using dry flowing nitrogen, and the resulting residue is derivatized using N-(tert.-butyldimethylsilyl)-N-methyltrifluoroacetamide and pyridine. The derivatized products are diluted to a final volume with toluene, chromatographed using a fused-silica capillary column, and detected with a quadrupole mass spectrometric detector in its selected-ion mode. Two independent, statistically unbiased, procedures were used to evaluate the detection limits for thiodiglycol; the values ranged between 4 and 16 microg(-1) groundwater.     

Solid-phase microextraction for the gas chromatography mass spectrometric determination of oxazole fungicides in malt beverages

This paper describes a method for the sensitive, selective, and solvent-free determination of six oxazole fungicide residues (hymexazol, drazoxolon, vinclozolin, chlozolinate, oxadixyl, and famoxadone) in malt beverages. Direct immersion solid-phase microextraction (DI-SPME) coupled to gas chromatography with mass spectrometry in the selected ion monitoring mode, GC-MS(SIM), is used. A comparison of the optimal fiber used, a polar carbowax-divinylbenzene 70-microm fiber, and a nonpolar polydimethylsiloxane 100-microm fiber was carried out. Optimal extraction conditions were 60 degrees C and an extraction time of 30 min under continuous stirring. Desorption was carried out at 250 degrees C for 5 min. Detection limits ranged from 0.006 to 0.3 microg L(-1) at a signal to noise ratio of 3, depending on the compound. The proposed method was successfully applied to malt beverages including malt, beer, and whisky, and none of the samples contained residues higher than detection limits.     

Determination of the fungicides vinclozolin and dicloran in soils using ultrasonic extraction coupled with solid-phase microextraction

Solid-phase microextraction (SPME) coupled to ultrasonic extraction was evaluated for extracting trace amounts of two agrochemical fungicides, vinclozolin and dicloran, in soil samples. Extraction was performed following two experimental approaches prior to the submission of the aqueous extracts to SPME-GC analysis. In the first approach, extraction involved sample homogenization with a water solution containing 5% (v/v) acetone and centrifugation prior to fiber extraction. In the second approach, the extraction of the fungicides from the soil samples was conducted using acetone as organic solvent which was then diluted with water to give a 5% (v/v) content. The pesticides were isolated with fused silica fiber coating with 85 μm polyacrylate. Parameters that affect both the extraction of the fungicides by the soil samples and the trapping of the analytes by the fiber were investigated and their impact on the SPME-GC-MS was studied. The procedures with respect to repeatability and limits of detection were evaluated by soil spiked with both analytes. Repeatability was between 5.6 and 14.2% and the limits of detection were 2-13 ng g⁻¹. The efficiency of acetone/SPME was generally better than that for water/SPME procedure showing good linearity (R²>0.99) with coefficient variations below 9%, recoveries higher than 91% and limits of detection between 2 and 3 ng g⁻¹. Finally, the recoveries obtained with acetone/SPME procedure were compared with the conventional liquid-liquid extraction using real soil samples. The acetone/SPME method was shown to be an inexpensive, fast and simple preparation method for the determination of target analytes at low nanogram per gram levels in soils.     

Determination of phthalate esters in vegetable oils using direct immersion solid-phase microextraction and fast gas chromatography coupled with triple quadrupole mass spectrometry

Phthalates are a group of synthetic compounds mainly used as plasticizers, which have been classified as endocrine-disrupting chemicals and potential human-cancer causing agents. They can be found in high amounts in foods, deriving mainly from plastic packaging. The analytical determination of these compounds is very challenging since they are ubiquitous. Therefore, minimization of sample manipulation is highly desirable.     

Determination of carphedon in human urine by solid-phase microextraction using capillary gas chromatography with nitrogen-phosphorus detection

Carphedon is a phenyl derivative of nootropil and is effective in increasing physical endurance and cold resistance, and is used for amnesia treatment. Carphedon was extracted from human urine samples by solid-phase microextraction with a 65 microns carbowax-divinylbenzene-coated fiber. This analysis was performed by using capillary gas chromatography with nitrogen-phosphorus detection and optimized at pH 9.6, 30% NaCl, immersion time 10 min and desorption in the GC injector at 250 degrees C for 3 min. The regression equation for carphedon showed good linearity in the range from 0.1 to 10 micrograms ml-1 for human urine samples. The limit of detection was 0.01 microgram ml-1. The developed method is more sensitive and simpler in sample preparation than liquid-liquid extraction and can be applied to doping analysis for stimulants.