Solid-phase microextraction coupled to gas chromatography with flame ionization detection for monitoring of organic solvents in working areas

A solid-phase microextraction (SPME) method was developed for air monitoring of organic solvents frequently used in chemical laboratories (namely pentane, dimethyl ether, acetone, acetonitrile, dichloromethane, hexane, ethylacetate, tetrahydrofurane, cyclohexane, benzene, and toluene). SPME sampling conditions and chromatographic separation were optimised. Linearity of response for each component of the mixture was tested. Standard solutions containing all the compounds, at three different concentrations, were analysed in triplicate and the relative standard deviations (RSDs) were calculated. The method was applied to the monitoring of indoor air in a research chemical laboratory. An SPME fibre was used as a sampling device inside the laboratory. Moreover an SPME fibre was used as a portable sampling device in order to determine the effective human exposure. Comparison of the portable and fixed sampling device showed differences in the amount of solvents associated with activities performed nearby.     

Headspace sampling and detection of cocaine, MDMA, and marijuana via volatile markers in the presence of potential interferences by solid phase microextraction–ion mobility spectrometry (SPME-IMS)

The successful air sampling and detection of cocaine, methylenedioxymethylamphetamine (MDMA), and marijuana using SPME-IMS achieved by targeting their volatile markers (methyl benzoate, piperonal, and terpenes, respectively) is presented. Conventional methods of direct air sampling for drugs are ineffective because the parent compounds of these drugs have very low vapor pressures, making them unavailable for headspace sampling. Instead of targeting the parent drugs, IMS was set at the optimal operating conditions (determined in previous work) in order to detect their volatile chemical markers. SPME is an effective and rapid air sampling technique for the preconcentration of analytes which is especially useful in confined spaces such as cargo containers, where the volatile marker compounds of drugs can be found in sufficient concentrations. By sampling the air using a 100 microm polydimethyl siloxane (PDMS) SPME fiber for as little as one minute, enough mass of the targeted volatile markers in the headspace of a quart-sized metal paint can (gallon, approximately 1101 cm(3)) which contained sub-gram quantities of the drug samples was recovered for IMS detection. Additionally, several potentially interfering compounds found in goods commonly shipped in cargo containers were tested individually as well as in mixtures with the drugs. No peak interferences were observed for MDMA or marijuana, and minimal peak interferences were found for cocaine.     

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.     

Field air analysis with SPME device

Solid-phase microextraction (SPME) devices were used for a wide scope of air-monitoring including field sampling and analysis of volatile organic compounds (VOCs), formaldehyde, and particulate matter (PM) in air. Grab (instantaneous) and time-weighted average (TWA) sampling were accomplished using exposed and retracted SPME fibers, respectively. Sampling time varied from 1 to 75 min, followed by analysis with a gas chromatograph (GC). A portable GC equipped with unique, in-series detectors: photoionization (PID), flame ionization (FID), and dry electrolytic conductivity (DELCD), provided almost real-time analysis and speciation for common VOCs during an indoor air quality surveys. Indoor air samples collected with SPME devices were compared with those collected using conventional National Institute for Occupational Safety and Health (NIOSH) methods. Air concentrations measured with the SPME device were as low as 700 parts-per-trillion (ppt) for semi-volatile organic compounds. SPME methodology proved to be more sensitive than conventional methods, and provided a simple approach for fast, cost-effective sampling and analysis of common VOCs in indoor air. SPME technology combined with fast portable GC reduced the sampling and analysis time to less than 15 min. The configuration offered the conveniences of immediate on-site monitoring and decision making, that are not possible with conventional methods. In addition, SPME fibers were applied to sampling of particulate matter in diesel engine exhaust. Linear uptake and particulate build-up on the fiber were observed. Preliminary research suggests that SPME fibers could also be applied to sampling of airborne particulate matter.     

Air sampling of aromatic hydrocarbons in the presence of ozone by solid-phase microextraction

Effects of ozone on air sampling of standard gas mixtures of aromatic hydrocarbons were tested using solid-phase microextraction (SPME). Standard concentrations of ozone ranging from 10 ppb (v/v) to 6400 ppm (v/v) were generated using an in-house built ozone generator based on corona discharge. Effects of temperature, discharge voltage, and oxygen flow on the ozone generation were tested. The working dc voltage had the greatest effect on generated ozone concentration and was proportional to the ozone concentration. Generation temperature and oxygen flow rate were inversely proportional to ozone concentrations. Produced ozone was mixed with standard benzene, toluene, ethylbenzene, and xylenes (BTEX) gas at less than 100 ppb (v/v). Air samples were collected with poly(dimethylsiloxane) (PDMS) 100 microm SPME fibers and analyzed by gas chromatography (GC)-flame ionization detection (FID) and GC-MS. Significant reductions of BTEX concentrations were observed. In addition, some products of BTEX-ozone-oxygen reactions were identified. SPME worked well as a rapid sampler for BTEX and BTEX-ozone-oxygen reaction products. No significant deterioration of the PDMS coating and no significant reduction of absorption capacity were observed after repeated exposure to ozone.     

Inside-tube solid-phase microextraction as an interlink between solid-phase microextraction and needle device for n-hexane evaluation in air and urine headspace

Monitoring the trace amount of chemicals in various samples remains a challenge. This study was conducted to develop a new solid-phase microextraction (SPME) system (inside-tube SPME) for trace analysis of n-hexane in air and urine matrix. The inside-tube SPME system was prepared based on the phase separation technique. A mixture of carbon aerogel and polystyrene was loaded inside the needle using methanol as the anti-solvent. The air matrix of n-hexane was prepared in a Tedlar bag, and n-hexane vapor was sampled at a flow rate of 0.1 L/min. Urine samples spiked with n-hexane were used to simulate the sampling method. The limit of detection using the inside-tube SPME was 0.0003 μg/sample with 2.5 mg of adsorbent, whereas that using the packed needle was 0.004 μg/sample with 5 mg of carbon aerogel. For n-hexane analysis, the day-to-day and within-day coefficient variation were lower than 1.37%, with recoveries over 98.41% achieved. The inside-tube SPME is an inter-link device between two sample preparation methods, namely, a needle trap device and an SPME system. The result of this study suggested the use of the inside-tube SPME containing carbon aerogel (adsorbent) as a simple and fast method with low cost for n-hexane evaluation.     

顶空固相微萃取-气相色谱-质谱法测定玩具中可迁移有机锡化合物

建立了顶空固相微萃取结合气相色谱-质谱联用技术测定玩具中10种可迁移有机锡化合物的方法。玩具材料经0.07 mol/L HCl浸泡2 h后,使用醋酸-醋酸钠缓冲溶液将浸泡液的pH值调至4.7,然后加入四乙基硼化钠将浸泡液中的有机锡化合物乙基化,在振荡条件下用100 μ m聚二甲基硅氧烷(PDMS)纤维进行顶空固相微萃取,萃取完成后将纤维插入气相色谱进样口进行热解吸,使用DB-5毛细管柱对10种有机锡化合物进行分离。10种有机锡化合物的检出限为0.5~5 μg/kg。两个加标水平(0.500 μg/L和5.00 μg/L)下的回收率分别为80.7%~118.7%和86.2%~120.5%,RSD均低于15%。应用该方法测定了玩具可触及材料(包括涂层、织物、塑料、木料)中的可迁移有机锡化合物。该方法简便、快速、灵敏度高,不需使用有毒有机溶剂,绿色环保。     

An unbreakable on-line approach towards sol-gel capillary microextraction

In this work a novel unbreakable sol-gel-based in-tube device for on-line solid phase microextraction (SPME) was developed. The inner surface of a copper tube, intended to be used as a high performance liquid chromatography (HPLC) loop, was electrodeposited by metallic Cu followed by the self assembled monolayers (SAM) of 3-(mercaptopropyl) trimethoxysilane (3MPTMOS). Then, poly (ethyleneglycol) (PEG) was chemically bonded to the -OH sites of the SAM already covering the inner surface of the copper loop using sol-gel technology. The homogeneity and the porous surface structure of the SAM and sol-gel coatings were examined using the scanning electron microscopy (SEM) and adsorption/desorption porosimetry (BET). The prepared loop was used for online in-tube SPME (capillary microextraction) of some selected polycyclic aromatic hydrocarbons (PAHs), as model compounds, from the aquatic media. After extraction, the HPLC mobile phase was used for on-line desorption and elution of the extracted analytes from the loop to the HPLC column. Major parameters affecting the extraction efficiency including the sample flow rate through the copper tube, loading time, desorption time and sample volume were optimized. For investigating the sorbent efficiency, four loops based on the copper tube itself, the copper tube after electrodeposition with Cu and the tubes with the SAMs and SAMs-sol-gel coating were made and compared. The SAMs-sol-gel coated loop clearly shows a prominently lead of at least 20-100 times of higher efficiency. The linearity for the analytes was in the range of 0.01-500 μg L(-1). Limit of detection (LOD) was in the range of 0.005-0.5 μg L(-1) and the RSD% values (n=5) were all below 8.3% at the 5 μg L(-1) level. The developed method was successfully applied to real water samples while the relative recovery percentages obtained for the spiked water samples were from 90 to 104%. The prepared loop exhibited long life time due to its remarkable solvent and mechanical stability. Different solvents such as methanol, acetonitrile and acetone were passed through the loop for many days and it was also used for more than 100 extractions/desorption of the selected analytes and no decrease in the peak areas was observed.     

膜萃取-气相色谱/微分离子迁移谱检测水中的1,4-二恶烷

利用膜萃取-气相色谱/微分离子迁移谱（ME-GC/DMS）对水中的1,4-二恶烷污染物进行了检测。考察了射频电压、采样流速、膜渗透时间、Trap预富集时间等参数对检测二恶烷的影响规律。结果显示：在优化条件下,二恶烷的定量线性范围为2.0~20.0 μg/L,检出限为0.67 μg/L。实验证明,二恶烷与5种氯代烃的混合物在ME-GC/DMS的二维分离谱图中得到特异性响应,增加了识别的准确性。该研究为发展现场实时监测地下水中污染物的方法提供了重要参考。     

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。     

A Comparison of SnifProbe and SPME for Aroma Sampling

The popular solid phase micro extraction (SPME) device and method is compared with SnifProbe (Gordin and Amirav in J Chromatogr A 903:155–172, 2000) in their application for coffee aroma sampling for its analysis. The main difference between SPME and SnifProbe is in the relative motion of the sampled air. While SPME is based on static air sampling and the achievement of equilibrium, SnifProbe is based on active air pumping through the adsorption trap. A second important difference concerns the sample introduction into the GC injector for its intra injector thermal desorption. SPME is based on the use of a special syringe for sample introduction without any change to the injector, while SnifProbe requires a ChromatoProbe for sample introduction. We found that as a result of these differences, while SnifProbe provides a more faithful (representative) headspace and aroma sample collection, SPME is characterized by major compound dependent sample bias. In addition, SnifProbe enabled much faster sample collection than SPME. Since SnifProbe uses the ChromatoProbe for sample introduction into the GC, bigger sample collection/trapping devices such as silicone tubing can be used, and as a result, over ten times superior SnifProbe sensitivity (versus SPME) was demonstrated. Additional SnifProbe and SPME features are compared and discussed.     

Determination of petroleum hydrocarbons in contaminated soils using solid-phase microextraction with gas chromatography-mass spectrometry.

Manual solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry is investigated as a possible alternative for the determination of petroleum hydrocarbons in soils. Spiked onto an agricultural soil is a commercial diesel fuel (DF) with the following composition by weight: 12% linear alkanes, 52% saturated hydrocarbons (branched and cyclic), 21% alkylated aromatic hydrocarbons, 6% polycyclic aromatic hydrocarbons, and 9% unidentified compounds. The spiked soil samples are aged three days at room temperature before analysis. The optimal conditions for the SPME of DF from soils are examined and maximum sensitivity is obtained using a 100-microm polydimethylsiloxane fiber at a sampling temperature of 47 degrees C by sonication both in the headspace and directly through a water medium. The reproducibility of the whole technique showed a relative standard deviation of 10%. The parameters that can influence the recovery of DF (such as the time of SPME extraction, the presence of organic solvent and water, and the matrix) are investigated. The linearity is verified in the range of 40 to 1200 mg/L for the direct injection of DF, 0.1 to 1 mg/L for the SPME of DF from water, and 1 to 50 mg/Kg of dry soil for the SPME of DF from soils. The detection limits are respectively 0.5 mg/L, 0.02 mg/L, and 0.1 mg/Kg of dry soil. The method is corroborated by comparing the results with those obtained by the traditional way.     

Solid-phase microextraction under controlled agitation conditions for rapid on-site sampling of organic pollutants in water

An electric drill coupled with a solid-phase microextraction (SPME) polydimethylsiloxane (PDMS) fiber or a PDMS thin film was used for rapid sampling of polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. Laboratory experiments demonstrated that the sampling rates of SPME fiber and thin film can be predicted theoretically. Compared with the SPME fiber, the PDMS thin film active sampler exhibited a higher sampling rate and much better sensitivity due to its higher surface-to-volume ratio and its larger extraction phase volume. The amount of the analytes extracted by the thin film was around 100 times higher than those obtained by fiber, for both 5 min rapid sampling and equilibrium extraction. A new thin film active sampler was then developed for rapid on-site water sampling. The sampling kit included a portable electric drill, a copper mesh pocket, a piece of thin film, and a liner. Laboratory experiments indicated that the sampling remained in the linear uptake phase with this sampler to 8 min for the PAHs. Field test illustrated that this novel sampler was excellent for rapid on-site water sampling due to its short sampling period, high sampling efficiency and durability The thin film sampling kit facilitates on-site sampling, sample preparation, storage and transport. This new sampler is more user-friendly and easier to commercialize than previous samplers.     

Improved analysis of volatile halogenated hydrocarbons in water by purge-and-trap with gas chromatography and mass spectrometric detection

An analytical system composed of a purge-and-trap injection system coupled to gas chromatography with mass spectrometric detection (PTI-GC-MS) specific for the analysis of volatile chlorinated hydrocarbons (VCHCs) (chloroform; 1,1,1-trichloroethane; tetrachloromethane; 1,1,2-trichloroethylene; tetrachloroethylene) and trihalomethanes (THMs) (chloroform; bromodichloromethane; dibromochloromethane; bromoform) in water was optimised. Samples were purged and trapped in a cold trap (-100 degrees C) fed with liquid nitrogen (cryo-concentration). In order to make this method suitable also for only slightly contaminated waters, some modifications were made to PTI sample introduction, in order to avoid any air intake into the system. PTI, GC and MS conditions were optimised for halogenated compound analysis and limits of detection (LOD) were evaluated. The proposed method allows analysis of samples whose concentrations range from microg/L to ng/L. It is, therefore, applicable to drinking waters, in analyses required by law, and to slightly contaminated aqueous matrices, such as those found in remote areas, in environmental monitoring. Moreover, by changing cold trap temperature, even sparkling mineral waters can be analysed, thus avoiding CO2 interference during the cryo-concentration phase. Our method has been successfully used on real samples: tap water, mineral water and Antarctic snow.     

Triptycene‐Roofed Quinoxaline Cavitands for the Supramolecular Detection of BTEX in Air

Two novel triptycene quinoxaline cavitands ( DiTriptyQxCav and MonoTriptyQxCav ) have been designed, synthesized, and applied in the supramolecular detection of benzene, toluene, ethylbenzene, and xylenes (BTEX) in air. The complexation properties of the two cavitands towards aromatics in the solid state are strengthened by the presence of the triptycene moieties at the upper rim of the tetraquinoxaline walls, promoting the confinement of the aromatic hydrocarbons within the cavity. The two cavitands were used as fiber coatings for solid‐phase microextraction (SPME) BTEX monitoring in air. The best performances in terms of enrichment factors, selectivity, and LOD (limit of detection) values were obtained by using the DiTriptyQxCav coating. The corresponding SPME fiber was successfully tested under real urban monitoring conditions, outperforming the commercial divinylbenzene–Carboxen–polydimethylsiloxane (DVB–CAR–PDMS) fiber in BTEX adsorption.     

Analysis of polycyclic aromatic hydrocarbons in solid matrixes by solid-phase microextraction coupled to a direct extraction device

Analysis of polycyclic aromatic hydrocarbons (PAHs) standards in model systems was carried out by solid-phase microextraction (SPME) coupled to a direct extraction device (DED) and subsequent gas chromatography/mass spectrometry (GC/MS). PAHs standard was added to gelatine systems at different concentrations. Extraction process was carried out by SPME-DED at 25 °C for 60 min. Polydimethylsiloxane 100 μm (PDMS 100 μm), divinylbenzene/polydimethylsiloxane 65 μm (DVB/PDMS 65 μm) and polyacrilate 85 μm (PA 85 μm) SPME fibres were tested. SPME-DED satisfactorily extracted PAHs with a molecular weight (MW) lower than 206 from the gelatine system. All fibres showed a good reproducibility (residual standard deviation (RSD) between 5.24% and 18.25%), linearity (regression coefficients between 0.8959 and 0.9983) and limit of detection (LOD) (between 0.008 and 0.138 ng mL⁻¹). Presence of PAHs in different smoked meat products was also tested by SPME-DED. Different low MW PAHs were satisfactorily detected from all the foodstuffs studied. SPME-DED appears as a rapid, non-destructive technique for primary screening of low MW PAHs in solid matrixes.     

固相微萃取-气相色谱/质谱测定植物叶片中的挥发性物质

采用固相微萃取（SPME)方法吸附植物叶片中的挥发性物质,然后采用气相色谱/质谱法（GC/MS）分析了挥发性物 质的成分。在45 ℃水浴温度下,采用Polyacrylate(85 μm)固相微萃取头,在广口瓶中植物叶片的上方顶空吸附60 min,然后进行GC/MS分析。结果表明,植物叶片中的挥发性物质得到了很好的分离,受山楂叶螨(Tetraychus vienneis) 危害严重的植物的完好叶片中的挥发性物质均含有顺-3-己烯-1-醇乙酸酯、顺-3-己烯-1-醇丁酸酯和α-法呢烯,且含量 较大。初步确定这些物质是对山楂叶螨具有引诱作用的主要物质,从而为利用天然生物活性物质防治山楂叶螨提供了理论 依据。     

Application of solid phase microextraction and needle trap device with silica composite of carbon nanotubes for determination of perchloroethylene in laboratory and field

In this paper solid phase microextraction (SPME) and needle trap device (NTD) as two in-progress air monitoring techniques was applied with silylated composite of carbon nanotubes for sampling and analysis of perchloroethylene in air. Application of SPME and NTD with proposed nano-structured sorbent was investigated under different laboratory and experimental parameters and compared to the SPME and NTD with CAR/PDMS. Finally the two samplers contained nano-sorbent used as a field sampler for sampling and analysis of perchloroethylene in dry cleaning. Results revealed that silica composite form of CNTs showed better performance for adsorbent of perchloroethylene. SPME and NTD with proposed sorbent was demonstrated better responses in lower levels of temperature and relative humidity. For 5 days from sampling the relative responses were more than 97% and 94% for NTD and SPME, respectively. LOD were 0.023 and 0.014 ng mL⁻¹ for SPME coated CNTs/SC and CAR/PDMS, and 0.014 and 0.011 ng mL⁻¹ for NTD packed with CNTs/SC and CAR/PDMS, respectively. And for consecutive analysis RSD were 3.9–6.7% in laboratory and 4.43–6.4% in the field. In the field study, NTD was successfully applied for determining of the PCE in dry cleaning. The results show that the NTD packed with nanomaterial is a reliable and effective approach for the sampling and analysis of volatile compounds in air.     

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.     

Sampling volatile organic compounds using a modified solid phase microextraction device

Headspace solid phase microextraction (headspace SPME) has been demonstrated to be an excellent solvent-free sampling method. One of the major factors contributing to the success of headspace SPME is the concentrating effect of the fiber coating toward organic compounds. The affinity of the fiber coating toward very volatile analytes, such as chloromethane, may, however, not be large enough for detection at the parts per trillion concentration level. Static headspace analysis, on the other hand, is very effective for these very volatile compounds. As analyte volatility decreases, the sensitivity of static headspace analysis drops. The complementary nature of these two sampling methods can be exploited by combining the SPME device with a gastight syringe. The sensitivity of the new sampling device is better than that of SPME for very volatile compounds or that of static headspace analysis for less volatile compounds. This new method can sample a wide range of compounds from chloromethane (b.p. −24°C) to bromoform (b.p. 149°C) with estimated limits of detection at the low parts per trillion level.