Fully automated in-tube solid-phase microextraction for liquid samples coupled to gas chromatography

An online device is described in which analytes are extracted from a liquid sample by means of in-tube solid-phase microextraction (in-tube SPME), pulse released by rapid heating, and transferred to a gas chromatograph in a fully automated way. Switching of the sample and gas flows as well as the heating of the extraction tube and the valves is controlled by a remote computer system. Results obtained for river water and for aqueous standard solutions of phenanthrene are presented and are compared to the performance of standard SPME.     

固相微萃取-气相色谱法和气相色谱-质谱法测定茶叶中氟虫腈及其代谢物残留

基于固相微萃取-气相色谱(SPME-GC)建立了检测茶叶中氟虫腈及其代谢物(脱亚硫酰基氟虫腈、硫化氟虫腈、氟虫腈砜、酰胺氟虫腈)残留的分析方法。实验中采用85 μm聚丙烯酸酯(PA)萃取头,萃取温度为60 ℃,萃取缓冲体系的pH值为9。当添加水平为2～10 μg/kg时,回收率在71.2%～109.3%之间,相对标准偏差(RSD)在1.2%～7.1%之间。方法的检出限(LOD)和定量限(LOQ)分别在0.3～1.2 μg/kg和1.0～4.0 μg/kg之间。对所建立的方法采用气相色谱-质谱(GC-MS)进行确证,结果令人满意。本方法灵敏度、精密度和LOD均符合残留分析要求,具有快速、灵敏度高的特点,适合于茶叶中氟虫腈及其代谢物残留的痕量分析。     

Potential of solid phase microextraction and gas chromatography for quarantine-required detection of wood packaging in shipping containers

Solid phase microextraction (SPME) coupled with gas chromatography (GC) was used to detect terpene hydrocarbons inside shipping containers entering New Zealand. The utility of this system for the rapid detection of undeclared wood packaging for quarantine purposes was demonstrated. A portable dynamic air-sampling device was built to house a SPME fibre and allow the air from shipping containers to be sampled. The effects of sample flow rate and sampling time were investigated and sampling conditions of 100 mL/min for 30 s were chosen to keep sampling within the linear range. A CV of less than 15% (n = 12) was obtained for all the compounds analysed under these conditions. To obtain an estimate for the limit of detection (LOD) for the terpene hydrocarbons of interest, small quantities of lime oil were placed in an empty shipping container and the air inside was analysed. LOD (S/N = 3) was estimated to be in the order of 50-100 ng/L of air using GC with flame ionisation detection (GC-FID). Finally, the device was tested in fully laden containers and was shown to be effective for trapping terpene hydrocarbons indicative of wood packaging.     

Determination of furfural in beers,vinegars and infant formulas by solid-phase microextraction and gas chromatography/mass spectrometry

The solid-phase microextraction (SPME) technique with on-fibre derivatisation was evaluated for the analysis of furfural in infant formulas, beers, and vinegars. The poly(dimethylsiloxane)/divinylbenzene (PDMS/DVB) fibre was used and O-2,3,4,5,6-(pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) was first loaded onto the fibre. Food sample of 2?mL was then placed in a 4?mL PTFE-capped glass vial. Headspace extraction by the SPME fibre was performed at 80°C for 20?min under 1100?rpm magnetic stirring with the addition of 40% sodium chloride. Afterwards, the SPME fibre was directly desorbed at the injection port of a gas chromatography/mass spectrometer (GC/MS), followed by the analysis of derivatives formed on-fibre. To avoid matrix interferences, standard addition method was performed. The adsorption-time profiles were examined. The precision, recovery and method detection limits (MDLs) were evaluated with spiked food samples. The relative standard deviations from different spiked samples were all less than 5% and the recoveries were 100?±?5%. With 2?mL of food sample, MDLs were in the range of 3.09?～?14.05?µg?L^?1. Compared with other techniques, the study shown here provided a simple, fast and reliable method for the analysis of furfural in food samples.     

固相微萃取-气相色谱法测定白洋淀水样中的邻苯二甲酸酯类化合物

建立了固相微萃取(SPME)-气相色谱法(GC)分析环境水样中痕量邻苯二甲酸酯类化合物(PAEs)的方法。选用100 μm聚二甲基硅烷(PDMS)萃取纤维,在磁力搅拌条件下,对水样中的PAEs萃取富集60 min,然后直接注入GC进样口,在250 ℃温度下解吸4 min后进行分析测定,13种PAEs能得到充分提取和分离。方法的重现性(以相对标准偏差(RSD)计为0.2%～9.7%,检出限为0.02～0.83 μg/L。将本方法应用于白洋淀水样中PAEs的分析检测发现,样品中邻苯二甲酸二异丁酯(DIBP)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二(2-乙基己基)酯(DEHP)检出率相对较高。对水样进行两个浓度水平(2.5 μg/L和5.0 μg/L)的加标试验,加标回收率为75.3%～111.0%,RSD为2.1%～8.0%(n=3),能够满足环境水样中痕量PAEs的测定要求。     

Determination of organochlorine pesticides by gas chromatography with solid-phase microextraction

Summary A study of different extraction techniques for the determination of a selected group of organochlorine compounds in surface waters is presented. Comparison of liquid-liquid extraction (LLE) with solid-phase extraction (SPE) and solid-phase microextraction (SPME) with fibers of different polarity shows that SPME with a recently commercialised fiber of polydimethylsiloxane divinylbenzene allows these compounds to be determined in surface waters with good extraction efficiencies. Extraction time, effect of temperature, ionic strength and pH were optimised, allowing quantification in agricultural effluents in the range 1.0–60 ng·L⁻¹.     

Determination of chemical warfare agents and related compounds in environmental samples by solid-phase microextraction with gas chromatography

Solid phase microextraction (SPME) is an increasingly common method of sample isolation and enhancement. SPME is a convenient and simple sample preparation technique for chromatographic analysis and a useful alternative to liquid-liquid extraction and solid phase extraction. SPME is speed and simply method, which has been widely used in environmental analysis because it is a rather safe method when dealing with highly toxic chemicals. A combination of SPME and gas chromatography (GC) permits both the qualitative and quantitative analysis of toxic industrial compounds, pesticides and chemical warfare agents (CWAs), including their degradation products, in air, water and soil samples. This work presents a combination of SPME and GC methods with various types of detectors in the analysis of CWAs and their degradation products in air, water, soil and other matrices. The combination of SPME and GC methods allows for low detection limits depending on the analyte, matrix and detection system. Commercially available fibers have been mainly used to extract CWAs in headspace analysis. However, attempts have been made to introduce new fiber coatings that are characterized by higher selectivities towards different analytes of interest. Environmental decomposition of CWAs leads to the formation of more hydrophilic products. These compounds may be isolated from samples using SPME and analyzed using GC however, they must often be derivatized first to produce good chromatography. In these cases, one must ensure that the SPME method also meets the same needs. Otherwise, it is helpful to use derivatization methods. SPME may also be used with fieldportable mass spectrometry (MS) and GC-MS instruments for chemical defense applications, including field sampling and analysis. SPME fibers can be taken into contaminated areas to directly sample air, headspaces above solutions, soils and water.     

Determination of cocaine and cocaethylene in urine by solid-phase microextraction and gas chromatography-mass spectrometry

In order to evaluate recent cocaine exposure or its coingestion with ethanol, a simple and sensitive solid-phase microextraction (SPME) procedure for determination of cocaine and cocaethylene in urine was developed and validated. A polydimethylsiloxane fibre (100 microm) was submersed in the urine sample for 20 min under magnetic stirring after alkalinization with solid buffer (NaHCO(3):K(2)CO(3), 2:1). Gas chromatography-mass spectrometry (GC-MS) was used to identify and quantify the analytes in selected ion monitoring mode (SIM). The limits of quantification were 5.0 ng/mL for both analytes. Good inter- and intra-assay precision was also observed (coefficient of variation <9%).     

Determination of polycyclic aromatic hydrocarbons in aqueous samples by microwave assisted headspace solid-phase microextraction and gas chromatography/flame ionization detection

The novel pretreatment technique, microwave-assisted heating coupled to headspace solid-phase microextraction (MA-HS-SPME) has been studied for one-step in situ sample preparation for polycyclic aromatic hydrocarbons (PAHs) in aqueous samples before gas chromatography/flame ionization detection (GC/FID). The PAHs evaporated into headspace with the water by microwave irradiation, and absorbed directly on a SPME fiber in the headspace. After being desorbed from the SPME fiber in the GC injection port, PAHs were analyzed by GC/FID. Parameters affecting extraction efficiency, such as SPME fiber coating, adsorption temperature, microwave power and irradiation time, and desorption conditions were investigated.Experimental results indicated that extraction of 20 mL aqueous sample containing PAHs at optional pH, by microwave irradiation with effective power 145 W for 30 min (the same as the extraction time), and collection with a 65 μm PDMS/DVB fiber at 20 °C circular cooling water to control sampling temperature, resulted in the best extraction efficiency. Optimum desorption of PAHs from the SPME fiber in the GC hot injection port was achieved at 290 °C for 5 min. The method was developed using spiked water sample such as field water with a range of 0.1-200 μg/L PAHs. Detection limits varied from 0.03 to 1.0 μg/L for different PAHs based on S/N = 3 and the relative standard deviations for repeatability were <13%. A real sample was collected from the scrubber water of an incineration system. PAHs of two to three rings were measured with concentrations varied from 0.35 to 7.53 μg/L. Recovery was more than 88% and R.S.D. was less than 17%. The proposed method is a simple, rapid, and organic solvent-free procedure for determination of PAHs in wastewater.     

Determination of acrolein in french fries by solid-phase microextraction gas chromatography and mass spectrometry

The frying of foods in the home can be a cause of indoor pollution due to the formation of acrolein. The emission of acrolein formed during frying in soybean, corn, canola, sunflower and palm oils was studied. A GC/MS method has been developed to determine acrolein in French fries using SPME as the sampling technique after derivatization with 2,4-dinitrophenylhydrazine (DNPH). Optimum SPME conditions included desorption at 250°C for 2min after an adsorption time of 10min at room temperature. The method presented good resolution, repeatability, detection and quantification limits, and linearity of response. French fries were prepared in five different oils with four frying steps. The results showed that changes in acrolein concentration occurred after frying potatoes in different types of oil and at different frying cycles. Potatoes fried in soybean oil contained the lowest concentration of acrolein. Shoestring potatoes contained a lower concentration of acrolein than potato chips and French fries, respectively, because of the higher surface/volume ratio.     

固相萃取-气相色谱法测定北京市水样中的邻苯二甲酸酯

研究了使用毛细管柱（OV-1701）分离、FID作为检测器的气相色谱法测定水中5种邻苯二甲酸酯（PAEs）[邻苯二甲酸二乙酯（DEP）,邻苯二甲酸二丁酯（DBP）,邻苯二甲酸丁基苄基酯（BBP）,邻苯二甲酸二（2-乙基己基）酯（DEHP）,邻苯二甲酸二环己酯（DCHP）]的色谱条件。5种PAEs检出限在0．1～0．3μg／L之间,所测PAEs的质量浓度在0．5～100μg／L范围内,RSD在2．2％～3．3％之间,各物质校正曲线（质量浓度与峰面积）的相关系数在0．9970～0．9993之间。利用固相萃取技术萃取水中PAEs,回收率在82．5％～110．5％之间,RSD在1．1％～4．0％之间。北京市吴家村污水处理厂4个采样点中邻苯二甲酸酯浓度在（0．7～193．3）μg／L之间。北京市南护城河的3个采样点中邻苯二甲酸酯浓度在（0．1～241．8）μg／L之间。     

固相微萃取技术的进展及其在食品分析中应用的现状

固相微萃取(SPME)是当今色谱分析中使用极为广泛的样品前处理方法,这一技术将萃取、浓缩、解吸、进样等功能集于一体,灵敏度高且操作简便。该文简要介绍了近年来SPME涂层、装置及相应技术的演变,综述了SPME在国内外食品分析中的应用现状,并讨论了国内部分研究者在采用这一技术进行定量分析时存在的一些共性问题。     

气相色谱-质谱法测定聚氯乙烯包装材料和食品模拟物中的46种增塑剂

建立了46种增塑剂在聚氯乙烯(PVC)食品包装材料中的含量及其在水、3%乙酸、10%乙醇和橄榄油4种食品模拟物中迁移量的气相色谱-质谱(GC-MS)测定方法。食品包装材料、水质模拟物和橄榄油中增塑剂分别采用溶解-沉淀法、正己烷液-液萃取和凝胶渗透色谱(GPC)法提取。采用GC-MS法,在选择离子监测模式(SIM)下对46种增塑剂进行定性,采用外标法进行定量测定。各种增塑剂在0.1～2.0 mg/L质量浓度范围内呈线性,相关系数为0.9910～0.9999,各组分检出限均在0.005～0.05 mg/kg之间。在2种食品模拟物中,3个浓度添加水平下46种增塑剂的加标回收率在69.51%～107.21%之间,精密度(RSD, n=6)为3.53%～18.95%。该方法可满足PVC食品接触制品及4种不同性质的食品模拟物中多种类增塑剂的快速筛查和准确定性、定量测定要求。     

Evaluation of capillary gas chromatography columns for the determination of free volatile amines after solid-phase microextraction

Summary Gas-liquid chromatographic capillary columns coated with 14% diphenyldimethylpolysiloxane, base-deactivated 5% diphenyldimethylpolysiloxane, or poly(ethylene glycol), and deactivated porous polymer for capillary gas-solid chromatography were evaluated for analysis of low-molecular-weight (C₁−C₉) amines. Solid-phase microextraction with a polydimethylsiloxane fiber was used for headspace sampling and for introduction of the sample into the gas chromatograph. As expected, basic of aliphatic gaseous or volatile aliphatic amines (carbon number: C₁−C₄). A thick (e. g. 3 μm) film of 5% diphenyldimethylpolysiloxane enabled determination of analytes in a wider molecular-weight range (C₃−C₉) with acceptable efficiency and resolution.     

Determination of diphenylether herbicides in water samples by solid-phase microextraction coupled to liquid chromatography

Solid-phase microextraction (SPME) coupled to LC for the analysis of five diphenylether herbicides (aclonifen, bifenox, fluoroglycofen-ethyl, oxyfluorfen, and lactofen) is described. Various parameters of extraction of analytes onto the fiber (such as type of fiber, extraction time and temperature, pH, impact of salt and organic solute) and desorption from the fiber in the desorption chamber prior to separation (such as type and composition of desorption solvent, desorption mode, soaking time, and flush-out time) were studied and optimized. Four commercially available SPME fibers were studied. PDMS/divinylbenzene (PDMS/DVB, 60 microm) and carbowax/ templated resin (CW/TPR, 50 microm) fibers were selected due to better extraction efficiencies. Repeatability (RSD, < 7%), correlation coefficient (> 0.994), and detection limit (0.33-1.74 and 0.22-1.94 ng/mL, respectively, for PDMS/DVB and CW/TPR) were investigated. Relative recovery (81-104% for PDMS/DVB and 83-100% for CW/TPR fiber) values have also been calculated. The developed method was successfully applied to the analysis of river water and water collected from a vegetable garden.     

气相色谱测定食品中丙酸及其盐类

建立了气相色谱测定食品中丙酸及丙酸盐的分析方法。针对含油脂和不含油脂的食品，分别建立了脱脂提取法和直接提取法。考察不同pH值对丙酸溶解性和加标回收率的影响，通过对净化条件、pH值、提取剂的种类和提取次数等条件的优化，确定最佳处理条件为：样品加盐酸溶液调节pH ≤ 2，用5 mL正己烷脱脂，用5 mL乙酸乙酯提取2次，合并提取液，使用HP-INNOWAX毛细管色谱柱对丙酸进行分离，用氢火焰离子化检测器检测，外标法定量。结果表明，使用脱脂提取法得到丙酸的回收率为87.5%~97.6%，相对标准偏差为3.09%~6.86%（n=6）；使用直接提取法得到丙酸的平均回收率为90.1%~102.1%，相对标准偏差为3.32%~6.33%（n=6）。两种方法的线性范围为2~1000 mg/L（相关系数为0.9998），检出限为0.003 g/kg，定量限为0.01 g/kg。方法适用于多种食品中丙酸的检测，具有准确、快速、简便、灵敏度高等优点，为食品中丙酸含量的测定提供了新途径。     

气相色谱法测定高分子食品包装材料中抗氧化剂的残留量

建立了气相色谱测定高分子食品包装材料中抗氧化剂丁基羟基茴香醚(BHA)、二丁基羟基甲苯(BHT)和特丁基对苯二酚(TBHQ)残留量的分析方法。用环己烷超声萃取高分子食品包装材料样品,考察了萃取时间、温度对抗氧化剂萃取量的影响。萃取液经气相色谱柱HP-50+毛细管柱(30 m×0.53 mm×1 μm)分离,电子捕获检测器(ECD)检测,外标法定量。结果表明: 在抗氧化剂添加量为3.00～10.0 mg/kg范围内,BHT、BHA、TBHQ在高分子食品包装材料中的平均添加回收率分别为88%～93%、92%～101%和83%～97%,相对标准偏差(RSD, n=5)分别为2.01%～2.89%、2.11%～3.19%和2.99%～4.02%;检出限(信噪比为3)分别为0.5、0.5和0.8 mg/kg。对实际高分子食品包装材料样品的检测结果表明3种抗氧化剂在不同材质中均有检出: 塑料材料中抗氧化剂的含量较少,仅有BHT、BHA被检出,含量为6.3～7.8 mg/kg;橡胶材料中3种抗氧化剂均被检出,含量为9.3～28.4 mg/kg。该方法准确、灵敏、重现性好,适用于高分子食品包装材料中抗氧化剂残留量的检测。     

Determination of isophorone in food samples by solid-phase microextraction coupled with gas chromatography-mass spectrometry

A simple and sensitive method for the determination of isophorone in food samples was developed by headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). Isophorone was separated within 10 min by GC-MS using a DB-1 capillary column and detected with selective ion monitoring mode. The HS-SPME using a polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber provided effective sample enrichment, and was carried out by fiber exposition at 60 degrees C for 45 min. The extracted isophorone was easily desorbed by fiber exposition in the injection port of a capillary GC-MS system, and carryover was not observed. Using this method, the calibration curve of isophorone was linear in the range 20-1000 pg/mL, with a correlation coefficient 0.9996 (n = 18), and the detection limit (S/N = 3) was 0.5 pg/mL. The HS-SPME/GC-MS method showed 25,000-fold higher sensitivity than the direct injection method (1 microL injection). The within-day and between-day precisions (relative standard deviations) at the concentration of 1 ng/mL isophorone were 3.9% and 6.1% (n=5), respectively. This method was successfully applied to the analysis of food samples without interference peaks. The recoveries of isophorone spiked into food sample were above 84% for a 50 or 500 pg/mL spiking concentration. The analytical results of the contents of isophorone in various food samples were presented.     

Passive sampling of airborne furan indoors by solid-phase microextraction

Furan may be formed in food under heat treatment and is highly suspected to appear in indoor air. The possible exposure to indoor furan raises concerns because it has been found to cause carcinogenicity and cytotoxicity in animals. To determine airborne furan, solid-phase microextraction (SPME) technique was utilised as a diffusive sampler. The Carboxen/Polydimethylsiloxane (CAR/PDMS, 75 μm) fibre was used, and the SPME fibre assembly was inserted into a polytetrafluoroethene tubing. Furan of known concentrations was generated in Tedlar gas bags for the evaluation of SPME diffusive samplers. After sampling, the sampler was inserted into the injection port of a gas chromatograph coupled with a mass spectrometer (GC/MS) for thermal desorption and analysis. Validation of the SPME device with active sampling by charcoal tube was performed side by side as well. The charcoal tube was desorbed by acetone before analysis with GC/MS. The experimental sampling constant of the sampler was found equal to (9.93 ± 1.28) × 10^?3 (cm³ min^?1) at 25°C. Furthermore, side-by-side validations between SPME device and charcoal tube showed linear relationship with r = 0.9927. The designed passive sampling device for furan has the advantages of both passive sampling and SPME technique and looks suitable for assessing indoor air quality.     

Determination of anatoxin-a in environmental water samples by solid-phase microextraction and gas chromatography-mass spectrometry

In the present work, a method was developed and optimized aiming at the determination of anatoxin-a in environmental water samples. The method is based on the direct derivatization of the analyte by adding hexylchloroformate in the alkalinized sample (pH = 9.0). The derivatized anatoxin-a was extracted by a solid-phase microextraction (SPME) procedure, submersing a PDMS fiber in an amber vial for 20 min under magnetic stirring. GC-MS was used to identify and quantify the analyte in the SIM mode. Norcocaine was used as internal standard. The following ions were chosen for SIM analyses (quantification ions in italics): anatoxin-a: 191, 164, 293 and norcocaine: 195, 136, 168. The calibration curve showed linearity in the range of 2.5-200 ng/mL and the LOD was 2 ng/mL. This method of SPME and GC-MS analysis can be readily utilized to monitor anatoxin-a for water quality control.