Preparation and characterization of new solid-phase microextraction fibers obtained by sol-gel technology and zirconium oxide electrodeposited on NiTi alloy

This study describes the use of zirconium oxide electrolytically deposited onto a NiTi alloy as a new substrate for sol-gel reactions. Polydimethylsiloxane (PDMS) was used to coat the fiber after activation of the NiTi-ZrO(2) surface with sodium hydroxide solution followed by hydrochloric acid solution. Micrographs obtained by scanning electron microscopy (SEM) showed good uniformity of the PDMS coating on the proposed substrate and also permitted the evaluation of coating thickness, being approximately 25 microm. Thermal stability of the coating on the NiTi-ZrO(2) surface was evaluated, showing excellent stability up to 320 degrees C. The applicability of the proposed NiTi-ZrO(2)-PDMS fiber was evaluated through extraction of benzene, toluene, ethylbenzene and o-xylene (BTEX) from the headspace of aqueous samples. Some parameters affecting the extraction efficiency such as the salting-out effect, extraction temperature and extraction time were optimized by two consecutive two-level full-factorial experimental designs. This optimization allowed the experimental domain of maximum response to be attained and also the robustness range for the variables. Excellent detection limits in the range of 0.6-1.6 microg L(-1) were obtained as well as correlation coefficients higher than 0.99994. Precision for one fiber (n=7) was in the range of 1.4-4.0% and fiber-to-fiber reproducibility (n=5) was in the range of 3.9-6.7%. Comparison of the extraction profile of the proposed fiber with those of commercially available 100, 30 and 7 microm PDMS fibers showed that NiTi-ZrO(2)-PDMS had a better response compared to that of the 7 and 30 microm fibers. Such characteristics of the NiTi-ZrO(2)-PDMS fiber suggest that this fiber represents an excellent alternative for gas chromatography sample preparation.     

Preparation and application of NiTi alloy coated with ZrO(2) as a new fiber for solid-phase microextraction

In this study a NiTi alloy was applied as an SPME support due to its superelasticity and shape memory properties. This new metallic support was coated with ZrO(2) by electrodeposition using chronoamperometry. It was then evaluated for extraction of three classes of compounds from gaseous samples: alcohols, BTEX and trihalomethanes (THM). For the optimization of the parameters affecting the extraction efficiency of the target compounds, the univariate approach was used. Five fibers were electrodeposited to evaluate the reproducibility of the coating procedure, resulting in a relative standard deviation lower than 11.9%. The repeatability for one fiber (n=6) was lower than 8.5%. The detection limits were lower than 28.1, 20.8 and 0.18 microgL(-1) for alcohols, BTEX and THM, respectively, and the correlation coefficients were higher than 0.996. Taking into account the amount extracted per unit volume, the NiTi-ZrO(2) fiber showed a better extraction profile in comparison with the commercial fibers 7 microm PDMS, 85 microm PA and 30-50 microm DVB/CAR/PDMS. The new SPME fiber has a lifetime of over 300 extractions. Thus, it is a promising alternative for low-cost analysis, as it is robust, and easily and inexpensively prepared.     

Optimisation of a solid-phase microextraction method for synthetic musk compounds in water

A solid-phase microextraction method (SPME) for determining trace levels of synthetic musk fragrances in residual waters has been developed. Six polycyclic musks (cashmeran, phantolide, celestolide, traseolide, galaxolide and tonalide), and a macrocyclic musk (ambrettolide) have been analysed. A detailed study of the different parameters affecting the extraction process is presented. The main important factors affecting the microextraction process have been studied and optimised by means of a categorical factorial design. Two extraction modes (direct SPME and headspace SPME) were tried at different extraction temperatures using four different fiber coatings [polydimethylsiloxane (PDMS), Carboxen (CAR)-PDMS, PDMS-divinylbenzene (DVB) and Carbowax (CW)-DVB]. An extraction temperature of 100 degrees C sampling the headspace over the sample using CAR-PDMS or PDMS-DVB as fiber coatings were found to be the experimental conditions that lead to a more effective extraction. The method proposed is very simple and yields high sensitivity, with detection limits in the low pg/ml, good linearity and repeatability for all the target compounds. The total analysis time, including extraction and GC analysis, was only 45 min. The optimised method performed well when it was applied to waste water from an urban treatment plant.     

Automated solid phase dynamic extraction--extraction of organics using a wall coated syringe needle

Extractions of liquid samples were carried out using wall coated needles prepared from stainless steel capillary columns instead of syringe needles. This micro extraction technique was applied to the analysis of pesticides in water. Important parameters influencing the extraction such as sample velocity, extraction time and also the desorption parameters were investigated and optimized. Automation of this technique was realized using a conventional automatic sampler. Limits of detection were improved using the multiple extraction/desorption technique. Chromatographic data and limits of detection were compared with those obtained by solid phase micro extraction (SPME). Using a needle with a 7 microns film yielded limits of detection varying from 0.001-0.1 microgram/L and were in the same range as those resulting from the extraction using a 100 microns polydimethylsiloxane (PDMS) SPME fiber. The main advantages of the needle extraction technique were the significantly higher extraction speed and the practical aspects of a stable steel needle compared to those of a fragile fiber. The extraction speed using a needle with a 7 microns film was up to five times higher than the speed of SPME using a 100 microns PDMS fiber. The steel needle could be stressed mechanically in a higher extent than a SPME fiber. Sample volumes and aliquots of liquid media could be handled and moved from one bottle to another using the automatic sampler.     

Preparation of single-walled carbon nanotube fiber coating for solid-phase microextraction of organochlorine pesticides in lake water and wastewater

The feasibility of single-walled carbon nanotubes (SWCNTs) as adsorbents for solid-phase microextraction was investigated by using organochlorine pesticides (OCPs) as model compounds. SWCNTs were attached onto a stainless steel wire through organic binder. Potential factors affecting the extraction efficiency were optimized, including extraction time, extraction temperature, desorption time, desorption temperature, and salinity. The developed method has a linear range of 2-800 ng/L for most analytes, with coefficients of correlation ranging from 0.9911 to 0.9996, LODs ranged from 0.19 to 3.77 ng/L (S/N = 3), and RSDs in the range of 3.5-13.9% (n = 5). Compared with the commercial PDMS fiber, the SWCNT fiber has better thermal stability (over 350 degrees C) and longer life span (over 150 times). The developed method was applied to determine trace OCPs in lake water and wastewater samples with external standard calibration. Results showed that OCP contamination was very low in these samples, and HCHs were detected in almost all water samples while DDT concentrations were almost under detection limits in these samples. Recoveries obtained at 20 ng/L spiking level were in the range of 88.4-111% for OCPs in lake water. For wastewater samples, however, the recoveries were satisfactory for HCHs (63.6-97.1%) but relatively low for DDTs (44.7-116%) due to the high content of organic matter in wastewater.     

Optimization of headspace solid-phase microextraction gas chromatography-atomic emission detection analysis of monomethylmercury

Optimum conditions for headspace solid-phase microextraction (HS-SPME) in the analysis of monomethylmercury (MeHg) have been determined. Sodium tetra(n-)propylborate (NaBPr(4)) is used as derivatization reagent to promote volatility. A simple aluminium bar was used to cool the SPME fiber to about 2 degrees C during the equilibration phase just before extraction. HS-SPME was performed using different fibers. The 100 microm polydimethylsiloxane (PDMS) and 65 microm polydimethylsiloxane-divinylbenzene (PDMS-DVB) fibers showed the best results. Although the extraction efficiency for MeHg derivative of the polydimethylsiloxane-Carboxen (PDMS-CAR) fiber is similar to the other fibers, desorption of MeHg derivative from a PDMS-CAR fiber is poor. Factors affecting the HS-SPME process such as adsorption and desorption times, ionic strength (salting-out) and extraction temperature have been evaluated and optimized thoroughly. The highest extraction efficiency for the PDMS fiber was obtained by extraction at a low temperature (2 degrees C) immediately after equilibration at 30 degrees C. With the PDMS-DVB and PDMS-CAR fiber improvement of extraction efficiency at lower temperatures is negligible. Repeated extraction out of the same vial revealed that about 30% of MeHg derivative is extracted from the headspace with a PDMS fiber at 2 degrees C and about 70% with a PDMS-DVB fiber. Repeated extraction with two different fiber coatings showed that the PDMS-CAR fiber also extracts about 70% but that the desorption is incomplete. Attempts to improve the desorption failed due to degradation of the MeHg derivate at high injection temperatures. The limit of detection (3sigma) was 16 pg/L MeHg. The relative standard deviation (n = 8) for 100 pg/L of MeHg was found to be 5%. Linearity of the HS-SPME-GC-atomic emission detection method was established over at least two orders of magnitude in the range 0-2000 pg/L. Recovery of a surface water sample spiked at 2 ng/L was 85%. The suitability of the procedure was demonstrated by analysis of a surface water sample that showed a concentration of 100 pg/L MeHg. The optimized method can be used with standard commercial equipment without further adaptations.     

Preparation and application of poly(dimethylsiloxane)/beta-cyclodextrin solid-phase microextraction fibers

A novel poly(dimethylsiloxane)/beta-cyclodextrin (PDMS/beta-CD) coating was prepared for solid-phase microextraction (SPME). The PDMS/beta-CD coating proved to have a porous structure, providing high surface areas and allowing for high extraction efficiency. The coating had a high thermal stability (340 degrees C) and a long lifetime due to its chemical binding to the fiber surface. Polar phenols and amines were used to evaluate the character of the coating fiber by headspace (HS) extraction and thermal desorption, followed by GC-FID analysis. Parameters that affected the extraction process were investigated; these include extraction time and temperature, desorption time, pH, and ionic strength of the solution. For phenols, the range of linearity of the method was 4-500 microg/L and the LOD was 1.3-2.1 microg/L. For amines, the range of linearity was 1-1000 microg/L and the LOD was 1.2-2.8 microg/L. The presence of beta-CD not only increases the thermal stability of the fiber coating, but also enhances its selectivity. Compared with commercially available SPME fibers, the new phases show better selectivity and sensitivity towards polar compounds.     

Validation of an SPME method,using PDMS,PA, PDMS-DVB,and CW-DVB SPME fiber coatings,for analysis of organophosphorus insecticides in natural waters

Solid-phase microextraction (SPME) has been optimized and applied to the determination of the organophosphorus insecticides diazinon, dichlofenthion, parathion methyl, malathion, fenitrothion, fenthion, parathion ethyl, bromophos methyl, bromophos ethyl, and ethion in natural waters. Four types of SPME fiber coated with different stationary phases (PDMS, PA, PDMS-DVB, and CW-DVB) were used to examine their extraction efficiencies for the compounds tested. Conditions that might affect the SPME procedure, such as extraction time and salt content, were investigated to determine the analytical performance of these fiber coatings for organophosphorus insecticides. The optimized procedure was applied to natural waters - tap, sea, river, and lake water - spiked in the concentration range 0.5 to 50 micro g L(-1) to obtain the analytical characteristics. Recoveries were relatively high - >80% for all types of aqueous sample matrix - and the calibration plots were reproducible and linear (R(2)>0.982) for all analytes with all the fibers tested. The limits of detection ranged from 2 to 90 ng L(-1), depending on the detector and the compound investigated, with relative standard deviations in the range 3-15% at all the concentration levels tested. The SPME partition coefficients (K(f)) of the organophosphorus insecticides were calculated experimentally for all the polymer coatings. The effect of organic matter such as humic acids on extraction efficiency was also studied. The analytical performance of the SPME procedure using all the fibers in the tested natural waters proved effective for the compounds.     

Polypyrrole/graphene composite-coated fiber for the solid-phase microextraction of phenols

A polypyrrole (Ppy)/graphene (G) composite was developed and applied as a novel coating for use in solid-phase microextraction (SPME) coupled with gas chromatography (GC). The Ppy/G-coated fiber was prepared by electrochemically polymerizing pyrrole and G on a stainless-steel wire. The extraction efficiency of Ppy/G-coated fiber for five phenols was the highest compared with the fibers coated with either Ppy or Ppy/graphene oxide (GO) using the same method preparation. Significantly, compared with various commercial fibers, the extraction efficiency of Ppy/G-coated fiber is better than or comparable to 85 μm CAR/PDMS fiber (best extraction efficiency of phenol, o-cresol, and m-cresol in commercial fibers) and 85 μm polyacrylate (PA) fiber (best extraction efficiency of 2,4-dichlorophenol and p-bromophenol in commercial fibers). The effects of extraction and desorption parameters such as extraction time, stirring rate, and desorption temperature and time on the extraction/desorption efficiency were investigated and optimized. The calibration curves were linear from 10 to 1000 μg/L for o-cresol, m-cresol, p-bromophenol, and 2,4-dichlorophenol, and from 50 to 1000 μg/L for phenol. The detection limits were within the range 0.34-3.4 μg/L. The single fiber and fiber-to-fiber reproducibilities were <8.3 (n=7) and 13.3% (n=4), respectively. The recovery of the phenols spiked in natural water samples at 200 μg/L ranged from 74.1 to 103.9% and the relative standard deviations were <3.7%.     

Solid-phase microextraction gas chromatography-mass spectrometry determination of monoterpenes in honey

Solid-phase microextraction (SPME) using a 100 microm poly(dimethylsiloxane) (PDMS) fiber, followed by gas chromatography (GC-MS) determination, has been applied to the analysis of some monoterpenoids in honey. The extraction was performed by direct immersion of the fiber using a sampling period of 15 min with constant magnetic stirring (1100 rpm) and an extraction temperature of 20 degrees C. A 7 mL sample volume of an aqueous solution of honey with 25% of NaCl was placed in 15 mL glass vial fitted with screw cap and PTFE/silicone septum. Desorption was performed directly in the gas chromatograph injector port during 5 min at 250 degrees C using the splitless mode. The method is sensitive with detection limits between 11 and 25 microg L(-1), precise with coefficients of variation in the range 1.28 and 3.71%, and linear over more than one order of magnitude. The related conditions were used for honey sample analyses with recoveries between 71.8 and 90.9%. SPME remains an attractive alternative technique due to its rapidity and because it is a solvent free extraction method.     

基于低共熔溶剂的整体式萃取头的制备及其对湖水中3种多环芳烃的固相微萃取（英文）

采用氯化胆碱-乙二醇低共熔溶剂(DES)作致孔剂,制备了聚(甲基丙烯酸丁酯-乙二醇二甲基丙烯酸酯)[poly(BMA-EDMA)]固相微萃取头,并与超高效液相色谱法(UPLC)结合测定了湖水中的3种多环芳烃(PAHs)。实验与不使用DES致孔剂的固相微萃取头和商品化聚二甲硅氧烷(PDMS)萃取头进行比较,含DES的poly(BMA-EDMA)固相微萃取头的富集效果最好。系统考察了萃取条件(萃取时间、萃取溶剂、解吸时间、解吸溶剂及离子强度)对水样中多环芳烃萃取效率的影响。在最优的实验条件下,3种多环芳烃类化合物(萘、联苯、菲)的线性范围为0.1~6.0 mg/L(r≥0.990 3),检出限为2.1~4.9μg/L,回收率为86.4%~111.3%,相对标准偏差(RSD,n=6)为11.2%~15.1%。该法操作简便,稳定性好,成本低,适用于实际环境水样中多环芳烃类化合物的测定。     

Volatile compounds of red and white wines by headspace--solid-phase microextraction using different fibers

The behavior of four fibers [polydimethylsiloxane (PDMS), PDMS-divinylbenzene (DVB), carboxen (CAR)-PDMS, PDMS-DVB-CAR), is tested for the analysis of volatile compounds of white and red wine. The PDMS-DVB-CAR fiber is the most appropriate to obtain the most wide volatile profile of wines. The better extraction conditions are 40 min at 35 degrees C. Satisfactory data about the reproducibility and uptake are obtained for more than 40 volatile compounds of red and white wine.     

Automated solid phase dynamic extraction – Extraction of organics using a wall coated syringe needle

Extractions of liquid samples were carried out using wall coated needles prepared from stainless steel capillary columns instead of syringe needles. This micro extraction technique was applied to the analysis of pesticides in water. Important parameters influencing the extraction such as sample velocity, extraction time and also the desorption parameters were investigated and optimized. Automation of this technique was realized using a conventional automatic sampler. Limits of detection were improved using the multiple extraction / desorption technique. Chromatographic data and limits of detection were compared with those obtained by solid phase micro extraction (SPME). Using a needle with a 7 μm film yielded limits of detection varying from 0.001–0.1 μg/L and were in the same range as those resulting from the extraction using a 100 μm polydimethylsiloxane (PDMS) SPME fiber. The main advantages of the needle extraction technique were the significantly higher extraction speed and the practical aspects of a stable steel needle compared to those of a fragile fiber. The extraction speed using a needle with a ¶7 μm film was up to five times higher than the speed of SPME using a 100 μm PDMS fiber. The steel needle could be stressed mechanically in a higher extent than a SPME fiber. Sample volumes and aliquots of liquid media could be handled and moved from one bottle to another using the automatic sampler.     

Solid phase microextraction assisted by droplets-based liquid-liquid microextraction for analysis of volatile aromatic hydrocarbons in water by gas chromatography

A new technique for the analysis of volatile aromatic hydrocarbons by combining liquid-liquid microextraction with solid phase microextraction has been developed. The analytes were extracted from aqueous samples by an immobilized polydimethylsiloxane fiber assisted by the droplets of an appropriate organic solvent. Benzene, toluene, ethylbenzene, and o-xylene were used as target analytes. The main factors potentially affecting the microextraction such as the nature and the volume of organic solvent, polydimethylsiloxane (PDMS) swelling, extraction time, agitation, temperature, and salts were optimized. The method requires a very low consumption of organic solvent. The relative enrichment factor is in the range of 7.1-32.4 for extraction in the presence of dichloromethane at an optimum volume of 18 μL mL(-1) of aqueous sample. This enhancement over regular polydimethylsiloxane fiber is primarily the result of the fiber swelling and of a stable thin layer of organic solvent attached to the surface of the PDMS fiber. The limit of detection ranges from 0.02 to 0.65 ng mL(-1) for the target compounds using a 7-μm bonded polydimethylsiloxane coating and a flame ionization detector. The validity of this method is demonstrated by the analysis of a real waste water sample.     

新型固相微萃取涂层材料的制备及其在迷迭香挥发性成分检测分析中的应用

利用溶胶-凝胶法制备了含全羟基取代五元瓜环(Q[5])的新型固相微萃取涂层。以全羟基取代五元瓜环(Q[5](OH)_(10))和端羟基聚二甲基硅氧烷(OH-PDMS)为起始原料,γ-缩水甘油醚氧丙基三甲氧基硅烷(KH-560)为偶联试剂,通过水解和缩合反应制备了PDMS/Q[5](OH)_(10)新型涂层。采用扫描电镜、傅立叶红外光谱、差示扫描量热分析和热重分析分别对涂层组织形貌、结构特点以及热稳定性进行了检测。结果表明该涂层具有较大的表面积,良好的热稳定性(360℃)和较长的使用寿命。将该涂层制备成固相微萃取纤维,联用气相色谱-质谱技术对迷迭香的挥发性成分进行了分析,并用面积归一法测定其相对含量。优化的萃取条件为:萃取温度80℃,萃取时间45 min,样品质量0.200 0 g。在此条件下,鉴定出迷迭香中的25种挥发性成分,含量较高的成分为1,8-桉叶素、樟脑和α-蒎烯。将自制纤维与商用纤维(PDMS/DVB/CAR)的萃取效果进行了对比,从萃取成分的数量和含量来看,自制纤维的萃取效果和商用纤维相当,说明自制的固相微萃取纤维可用于植物中挥发性成分的快速检测分析。     

Stir bar sorptive extraction and comprehensive two-dimensional gas chromatography coupled to high-resolution time-of-flight mass spectrometry for ultra-trace analysis of organochlorine pesticides in river water

A method for the determination of ultra-trace amounts of organochlorine pesticides (OCPs) in river water was developed by using stir bar sorptive extraction (SBSE) followed by thermal desorption and comprehensive two-dimensional gas chromatography coupled to high-resolution time-of-flight mass spectrometry (SBSE-TD-GC×GC-HRTOF-MS). SBSE conditions such as extraction time profiles, phase ratio (β: sample volume/polydimethylsiloxane (PDMS) volume), and modifier addition, were examined. Fifty milli-liter sample including 10% acetone was extracted for 3 h using stir bars with a length of 20 mm and coated with a 0.5 mm layer of PDMS (PDMS volume, 47 μL). The stir bar was thermally desorbed and subsequently analyzed by GC×GC-HRTOF-MS. The method showed good linearity over the concentration range from 50 to 1000 pg L(-1) or 2000 pg L(-1) for all analytes, and the correlation coefficients (r(2)) were greater than 0.9903 (except for β-HCH, r(2)=0.9870). The limit of detection (LOD) ranged from 10 to 44 pg L(-1). The method was successfully applied to the determination of 16 OCPs at pg L(-1) to ng L(-1) in river water. The results agree fairly well with the values obtained by a conventional liquid-liquid extraction (LLE)-GC-HRMS (selected ion monitoring: SIM) method using large sample volume (20 L). The method also allows screening of non-target compounds, e.g. pesticides and their degradation products, polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and pharmaceuticals and personal care products (PPCPs) and metabolites in the same river water sample, by using full spectrum acquisition with accurate mass in GC×GC.     

Headspace solid phase microextraction in-situ supercritical fluid extraction coupled to gas chromatography-tandem mass spectrometry for simultaneous determination of perfluorocarboxylic acids in sediments

Headspace solid phase microextraction (HS-SPME) in-situ supercritical fluid extraction (SFE) was investigated for the determination of trace amounts of perfluorocarboxylic acids (PFCAs) in sediments. Quantitation was performed by using gas chromatography coupled to negative chemical ionization-tandem mass spectrometry (GC-NCI-MS/MS). The optimum conditions of HS-SPME following SFE were obtained using 500 μL n-butanol as a derivatization reagent in supercritical carbon dioxide with static extraction for 10 min, then dynamic extraction for 20 min at 30 MPa and 70 °C and simultaneous collected with 100 μm film thickness PDMS fiber. The linear range of proposed method was from 5 to 5000 ng g(-1), with limit of detection ranging from 0.39 to 0.54 ng g(-1) and limit of quantitation ranging from 1.30 to 1.80 ng g(-1). The developed method was successfully applied to analyze PFCAs in sediments from rivers and beach near industrial areas. The concentrations of PFCAs determined are from 282 to 4473 ng g(-1).     

纳米多孔双金属氧化物在镍钛合金纤维上的原位生长及其对多环芳烃的选择性固相微萃取

采用阳极氧化法在镍钛合金(NiTi)纤维上原位生长了双金属氧化物纳米孔(NiTiONPs)涂层,通过扫描电镜(SEM)和能谱(EDS)考察了电解质组成和电压对形貌的影响。将NiTiONPs涂层的NiTi纤维与高效液相色谱-紫外检测器联用,研究了4种典型芳香分析物的萃取性能。结果表明,富含TiO2的NiTiONPs涂层对多环芳烃(PAHs)具有良好的萃取效率,尤其对苯并[a]芘的萃取选择性优于市售聚二甲基硅氧烷纤维和聚丙烯酸酯纤维。在优化条件下,PAHs的线性范围为0.05~200μg/L,相关系数均大于0.999,检出限为0.012~0.134μg/L。对单支纤维日内和日间分析的相对标准偏差(RSDs)分别为4.0%~5.5%和6.0%~6.8%,使用分批组装的5支纤维分析的RSDs为6.4%~7.6%。实际水样分析的加标回收率为84.5%~111.5%。所制备NiTi纤维至少可重复使用250次以上,重现性好。     

Analysis of triazine in water samples by solid-phase microextraction coupled with high-performance liquid chromatography

Solid-phase microextraction (SPME) coupled with high-performance liquid chromatography (HPLC) for the determination of triazine is described. Carbowax/templated resin (CW/TPR, 50 μm), polydimethylsiloxane/divinylbenzene (PDMS/DVB, 60 μm), polydimethylsiloxane (PDMS, 100 μm), and polyacrylate (PA, 85 μm) fibers were evaluated for extraction of the triazines. CW/TPR and PDMS/DVB fibers were selected for further study. Several parameters of the extraction and desorption procedure were studied and optimized (such as types of fibers, desorption mode, desorption time, compositions of solvent for desorption, soaking periods and the flow rate during desorption period, extraction time, temperature, pH, and ionic strength of samples). Both CW/TPR and PDMS/DVB fibers are acceptable; a simple calibration-curve method based on simple aqueous standards can be used. The linearity of this method for analyzing standard solution has been investigated over the range 5-1000 ng mL⁻¹ for both PDMS/DVB and CW/TPR fibers. All the correlation coefficients in the range 5-1000 ng mL⁻¹ were better than 0.995 except Simazine and Atratone by CW/TPR fiber. The R.S.D.s range from 4.4% to 8.8 % (PDMS/DVB fiber) and from 2.4% to 7.2% (CW/TPR fiber). Method-detection limits (MDL) are in the range 1.2-2.6 and 2.8-3.4 ng mL⁻¹ for the two fibers. These methods were applied to the determination of trazines in environmental water samples (lake water).     

Poly(phthalazine ether sulfone ketone) as novel stationary phase for stir bar sorptive extraction of organochlorine compounds and organophosphorus pesticides

A novel poly(phthalazine ether sulfone ketone) (PPESK) film prepared by immersion precipitation technique was coated on stir bars for sorptive extraction. Scanning electron micrographs showed that the coating has a denser porous surface (about 1 microm in thickness) with a sponge-like sublayer, and the thickness of the coating was 250 microm. The PPESK coated stir bar has high thermostability (290 degrees C) and long lifetime (50 times). The extraction properties of this stir bar were evaluated for the extraction of both polar and semi-polar analytes, including organochlorine compounds and organophosphorus pesticides. The PPESK stir bar was proved to show higher affinity towards polar compounds than that of PDMS coated stir bar and higher sample load compared with corresponding PPESK fiber. It was applied to the determination of organochlorine compounds in seawater samples and organophosphorus pesticides in juices by gas chromatographic analysis. The effect of sample matrix was evaluated at optimized condition of extraction temperature, extraction time and salt concentration. Limits of detection were in the range of 0.05-2.53 ng L(-1) for organochlorine compounds in seawater samples using electron capture detector (ECD), with precisions of less than 11% RSD. Limits of detection for organophosphorus pesticides were in the range of 0.17-2.25 ng L(-1) and 2.47-10.3 ng L(-1) in grape and peach juice, respectively, using thermionic specified detector (TSD), with precisions of less than 12% RSD and 20% RSD, respectively.