Determination of volatile organic compounds in urban and industrial air from Tarragona by thermal desorption and gas chromatography-mass spectrometry

This study describes the optimisation of an analytical method to determine 54 volatile organic compounds (VOCs) in air samples by active collection on multisorbent tubes, followed by thermal desorption and gas chromatography-mass spectrometry. Two multisorbent beds, Carbograph 1/Carboxen 1000 and Tenax/Carbograph 1TD, were tested. The latter gave better results, mainly in terms of the peaks that appeared in blank chromatograms. Temperatures, times and flow desorption were optimised. Recoveries were higher than 98.9%, except methylene dichloride, for which the recovery was 74.9%. The method's detection limits were between 0.01 and 1.25 μg m⁻³ for a volume sample of 1200 ml, and the repeatability on analysis of 100 ng of VOCs, expressed as relative standard deviation for n = 3, was lower than 4% for all compounds. Urban and industrial air samples from the Tarragona region were analysed. Benzene, toluene, ethylbenzene and xylenes (BTEX) were found to be the most abundant VOCs in urban air. Total VOCs in urban samples ranged between 18 and 307 μg m⁻³. Methylene chloride, 1,4-dichlorobenzene, chloroform and styrene were the most abundant VOCs in industrial samples, and total VOCs ranged between 19 and 85 μg m⁻³.     

热脱附-气相色谱-质谱法测定环境空气中67种挥发性有机物

采用热脱附-气相色谱-质谱法,建立了同时分析环境空气中67种挥发性有机物的分析方法。对比了5种不同填充材料不锈钢吸附管对78种挥发性有机物的吸附能力。填充材料为Tenax TA和Carbograph 1TD的混合填料吸附管对分析物的捕集效果最好,在30 mL/min高纯He气持续吹脱45 min的情况下,未发生穿透（即穿透率小于10%）的化合物达67种,分析物的种类包括芳香烃、脂肪烃、卤代烃和含氧挥发性有机物等。优化了使用该吸附管测定67种目标物时的热脱附条件。在5~100 ng范围内,目标化合物的色谱响应值与其量间具有良好的线性关系,其相关系数（r）均在1.0000~0.9977之间。方法检出限为0.3~2.4 ng,以采样体积1 L计算,检出限为0.3~2.4 μg/m³。加标量为20 ng时,7次重复实验目标化合物回收率均在81.6%~114.9%之间,目标化合物的相对标准偏差为1.2%~10.1%。采用该方法对某车厢内空气进行了检测,检出了包括酯类、卤代烷烃、卤代烯烃以及芳香族化合物在内的19种目标化合物,其范围为1.1~84.1 μg/m³。该方法准确、可靠、灵敏度高,实现了对环境空气中67种目标污染物的准确定量。     

顶空气相色谱-质谱法测定玩具中的10种挥发性有机物

建立了检测玩具中10种挥发性有机物(VOC)残留量的顶空气相色谱-质谱(HS-GC-MS)方法。样品经140 ℃、45 min静态顶空后,通过DB-624色谱柱分离和质谱检测,外标法定量。该方法对于不同VOC的定量限(LOQ)均在0.66 mg/kg以下,线性范围为0.001～2.0 μg,平均回收率在79%～106%之间,相对标准偏差(RSD)在0.4%～5.6%之间。该方法具有准确灵敏、简单快速等特点,将其应用于实际玩具样品的检测取得了良好效果。     

便携式气相色谱-质谱仪测定空气中挥发性有机污染物的准确性

便携式气相色谱-质谱仪(便携式GC-MS)能同时对多组分复杂有机物进行定性定量分析,在环境监测尤其是事故现场应急监测中发挥越来越重要的作用。本文比较了便携式GC-MS与EPATO-14A方法分析测定环境空气中低浓度挥发性有机物(VOCs)的性能,并探讨了利用定量环(loop环)模式测定高浓度VOCs的准确度。结果表明,采用内标标准曲线定量,HAPSITE便携式GC-MS测定空气中VOCs的检出限与EPATO-14A方法相当,准确度和精密度略低,但均符合环境监测分析的要求。利用loop环可对大部分10-6级的高浓度VOCs样品进行较为准确的测定,在突发性环境污染事故中可以得到基本准确的结果。     

Determination of volatile organic compounds in industrial wastewater plant air emissions by multi-sorbent adsorption and thermal desorption-gas chromatography-mass spectrometry

This paper describes the process of determining the presence of volatile organic compounds in air emissions from industrial wastewater treatment plants (WWTP). The analytical method, based on thermal desorption-gas chromatography-mass spectrometry, was developed to simultaneously determine of 99 volatile organic compounds (VOCs) in air samples. This method is rapid, environmentally-friendly (since no organic solvents are used to extract the analytes) and compatible with a large range of thermally stable polar and apolar compounds. The target VOCs were selected on the basis of their occurrence in real samples and their adverse effects on the environment and human health. To cover the wide range of target compounds, multisorbent tubes filled with Tenax TA and Carbograph 1TD were used. Method validation showed good repeatabilities, low detection limits, a high linear range and good recoveries. At a fixed sample volume of 600?mL no significant losses for any of the target compounds were found in the samples. Stability during storage indicated that samples must be keep refrigerated at 4°C and analysed within three days of collection. Real samples were taken from air emissions of an industrial wastewater treatment plant located in the Southern Industrial Area of Tarragona (Spain) with the aim of studying its contribution as a source of atmospheric VOCs. This WWTP collects wastewater from several chemical factories which produce isocyanates, polyurethanes, chlorinated organics and functional chemicals among other products. Samples from the collecting tank after the primary sedimentation showed higher VOC concentrations than samples from the secondary treatment tank. The most abundant VOCs found in these emissions are included in the USEPA List of Hazardous Air Pollutants. The highest values correspond to acrylonitrile (up to 1843?µg?m^?3) and styrene (up to 573.70?µg?m^?3). The levels of chloroform, 1,4-dioxane, ethylbenzene, 1,2,3-trimethylbenzene and 1,4-diethylbenzene were also high.     

Measurement of toxic volatile organic compounds in indoor air of semiconductor foundries using multisorbent adsorption/thermal desorption coupled with gas chromatography-mass spectrometry

A method for the qualitative and quantitative analysis of volatile organic compounds (VOCs) in the air of class-100 clean rooms at semiconductor fabrication facilities was developed. Air samples from two semiconductor factories were collected each hour on multisorbent tubes (including Carbopack B, Carbopack C, and Carbosieve SIII) with a 24-h automatic active sampling system and analyzed using adsorption/thermal desorption coupled with gas chromatography-mass spectrometry. Experimental parameters, including thermal desorption temperature, desorption time, and cryofocusing temperature, were optimized. The average recoveries and the method detection limits for the target compounds were in the range 94-101% and 0.31-0.89 ppb, respectively, under the conditions of a 1 L sampling volume and 80% relative humidity. VOCs such as acetone, isopropyl alcohol, 2-heptanone, and toluene, which are commonly used in the semiconductor and electronics industries, were detected and accurately quantified with the established method. Temporal variations of the analyte concentrations observed were attributed to the improper use of organic solvents during operation.     

吹扫捕集-GC-MS-SIM法测定水中挥发性硫化合物

建立了水中的二硫化碳(CS2)、甲硫醚(DMS)和二甲二硫醚(DMDS) 3种挥发性硫化合物分析方法.采用吹扫-捕集对水中的被测成分进行预富集,然后导入GC-MS系统中在选择离子模式(SIM)下进行检测.CS2、DMS和DMDS 3种硫化合物分别在0.03～3.42 μg/L,0.17～2.72 μg/L和0.04～3.41 μg/L范围内线性关系良好,相关系数r分别为0.9967、0.9930和0.9959;在不同的浓度下,平行测定5次后的相对标准偏差均小于6.0%;方法检出限为3.75,11.33和2.10 ng/L.     

Stability of workroom air volatile organic compounds on solid adsorbents for thermal desorption gas chromatography

The storage stability of the occupationally frequently occurring compounds, methylethylketone, methylisobutylketone, benzene, toluene, tetrachloroethylene, n-butylacetate, -pinene, β-pinene, limonene and n-decane, has been investigated on the adsorbents Tenax TA, Chromosorb 106 and Carbotrap using thermally desorbable tube type samplers, commonly utilized in ambient and workroom atmospheric measurements. Fifty and 500 ng of each compound were loaded on the various adsorbents tubes, stored at both ambient (20 °C) and refrigerated (4 °C) temperatures and analysed by means of thermal gas chromatography with mass spectrometric detection on days 0, 7, 14 and 28 after exposure. A 90% storage recovery was chosen as acceptance criteria for storage stability, and statistical testing by Student's t-test, analysis of variance and Bonferroni post hoc tests were employed to investigate the effect of the categorical variables storage time, storage temperature and analyte loading on the different adsorbents. Chromosorb 106 showed the overall best behaviour with recoveries of 90% or better for all analytes during the 28-day test period. Tenax TA and Carbotrap yielded lower recoveries and were more influenced by variations in storage time, storage temperature and analyte loading. Refrigerated temperatures were best avoided for storage on Tenax TA, but may increase the recovery of some compounds on Carbotrap (e.g. n-butylacetate). The blank build-up on the adsorbents was also investigated, and Carbotrap and Tenax TA showed no signs of artefact development over time. Chromosorb 106, however, contained inherently more artefacts that build up over time, which in spite of the excellent storage capability, may limit its use in field studies where long storage times are normal.     

气相色谱-质谱联用法测定腌制水产品中的挥发性N-亚硝胺类化合物

建立了气相色谱-质谱(GC-MS)快速测定腌制水产品中挥发性N-亚硝胺含量的分析方法。采用GC-MS测定了N-二甲基亚硝胺(NDMA)、N-二乙基亚硝胺(NDEA)、N-二丙基亚硝胺(NDPA)、N-亚硝基吡咯烷(NPYR)、N-亚硝基哌啶(NPIP)、N-二丁基亚硝胺(NDBA)6种化合物,考察了样品不同提取方法、不同固相萃取小柱、不同色谱柱对分离检测的影响。结果显示: 在10～1000 μg/L范围内,线性相关系数可达0.9998以上;重现性良好,相对标准偏差小于8%;回收率可达79%～105%;灵敏度高,检出限低,除NDPA为0.03 μg/kg外,其他5种N-亚硝胺为0.05 μg/kg。该方法前处理快速简捷,易于操作,适用于腌制水产品中N-亚硝胺残留量的检测工作。     

Quality control in quantification of volatile organic compounds analysed by thermal desorption-gas chromatography-mass spectrometry

This paper presents a detailed study on the calibration of a thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS)-based methodology for quantification of volatile organic compounds (VOCs) in gaseous and liquid samples. For the first time, it is documented to what extent three widely encountered problems affect precise and accurate quantification, and solutions to improve calibration are proposed. The first issue deals with the limited precision in MS quantification, as exemplified by high relative standard deviations (up to 40%, n=5) on response factors of a set of 69 selected VOCs in a volatility range from 16 Pa to 85 kPa at 298 K. The addition of [(2)H(8)]toluene as an internal standard, in gaseous or liquid phase, improves this imprecision by a factor of 5. Second, the matrix in which the standard is dissolved is shown to be highly important towards calibration. Quantification of gaseous VOCs loaded on a sorbent tube using response factors obtained with liquid standards results in systematic deviations of 40-80%. Relative response factors determined by the analysis of sorbent tubes loaded with both analytes and [(2)H(8)]toluene from liquid phase are shown to offer a reliable alternative for quantification of airborne VOCs, without need for expensive and often hardly available gaseous standards. Third, a strategy is proposed involving the determination of a relative response factor being representative for a group of analytes with similar functionalities and electron impact fragmentation patterns. This group method approach indicates to be useful (RSD approximately 10%) for quantifying analytes belonging to that class but having no standards available.     

热脱附-气相色谱-质谱法应用于工业源废气中挥发性有机物的目标和非目标筛查

建立了固相吸附热脱附-气相色谱-质谱(TD-GC-MS)综合筛查工业源废气中挥发性有机物(VOCs)的方法。对两种型号的固相吸附管进行了比较,最终选择使用Tenax SS TD Tubes吸附管。气体样品以恒定流速通过吸附管,富集分析物,经热脱附后,用GC-MS进行检测,目标化合物以内标法定量,非目标化合物的含量以甲苯的响应系数计算。方法检出限为1.06~5.44 ng,以采样体积300 mL计算,目标化合物的检出限为0.004~0.018 mg/m~3。吸附管平均加标回收率为78.4%~89.4%,相对标准偏差为3.9%~14.4%(n=7)。应用该方法对大连市某垃圾焚烧发电厂排放的废气进行VOCs目标及非目标化合物综合筛查,共检出29种VOCs,其中仅5种VOCs为预先设定的目标化合物,另外24种为非目标化合物,5种目标化合物含量仅占所有检出物总量的26.7%。证明了工业源废气VOCs分析中非目标化合物筛查的重要性,该研究思路对完整测定工业源挥发性有机污染物分布具有一定的借鉴意义。     

热脱附-气相色谱-三重四极杆串联质谱法测定环境空气中的挥发性有机物

采用热脱附(TD)结合气相色谱-三重四极杆串联质谱(GC-MS/MS)建立了环境空气中23种挥发性有机物(VOCs)同时检测的分析方法。空气样品通过主动采样的方式富集到装有Tenax-TA填料的热脱附管中,热解吸后在选择反应监测(SRM)模式下用GC-MS/MS进行检测,内标法定量。结果表明,23种VOCs在0.01~1 ng和1~100 ng低、高两个范围内线性关系良好,相关系数(r²)均大于0.99,方法定量限为0.00008~1 μ g/m³。加标水平为2、10和50 ng时,23种VOCs的平均回收率为77%~124%。除了最低加标水平的氯苯,相对标准偏差(RSD, n=6)均小于20%。对市内3个采样点的环境空气进行测定,其中苯、甲苯、乙苯、二甲苯、苯乙烯、1,2,4-三甲基苯和六氯丁二烯均有检出。实验证明,该TD和GC-MS/MS相结合的检测方法具有准确、可靠、灵敏度高等优点,适用于环境空气中VOCs的同时测定。     

Solid-phase microcolumn extraction and gas chromatography-mass spectrometry identification of volatile organic compounds emitted by paper

A rapid non-destructive sampling technique for the analysis of volatile organic compounds (VOCs) emitted by paper sheets is described. A capillary, which is connected to a microcolumn packed with Tenax TA, is inserted between two sheets at the centre of a paper stack encapsulated inside a PET/Al/PE composite foil. The other end of the microcolumn is connected to a gas-tight syringe and an appropriate volume of gaseous phase is aspirated. The microcolumn is then thermally desorbed in a modified GC inlet (modification is presented) and analysed by gas chromatography-mass spectrometry (GC-MS). In the chromatogram from the analysis of artificially aged paper sample 21 compounds were identified. Advantages of the method including the short sampling time (1 min), simplicity and economic aspect are discussed.     

Determination of volatile oak compounds in wine by headspace solid-phase microextraction and gas chromatography-mass spectrometry

A headspace solid-phase microextraction (HS-SPME) and gas chromatography (GC) coupled to mass spectrometry (MS) method was developed to identify and quantify 14 volatile oak compounds in aged red wines. The most important HS-SPME variables were optimised by experimental design technique in order to improved the extraction process. The selected conditions were: 10 mL of sample in 20 mL sealed vials with addition of 30% of sodium chloride (saturated solution), divinylbenzene-carboxen-polydimethylsiloxane (DVB-CAR-PDMS) fibre, 10 min of pre-incubation time, 70 degrees C of temperature and 60 min of extraction time without agitation. The features of the method were established for the studied compounds in terms of linear range, slope and intercept of the calibration graphs, detection and quantification limits and repeatability. For all compounds detection limits were below their threshold levels and repeatability, in terms of relative standard deviation, was good, with values between 3 and 11%. Finally, the method was applied to the analysis of six aged red wines by both internal standard and standard addition calibration methods. The concentrations obtained with both methods were statistically compared.     

Solid-phase microextraction—Gas chromatography to determine volatile organic sulfur compounds in the air at sewage treatment plants

Solid-phase microextraction (SPME) was applied to the determination of 7 volatile organic sulfur compounds (VOSCs), which were analysed by gas chromatography-mass spectrometry. The compounds studied were ethyl mercaptan (CH₃CH₂SH), dimethyl sulfide ((CH₃)₂S), carbon disulfide (CS₂), propyl mercaptan (C₃H₈S), butyl mercaptan (C₄H₁₀S), dimethyl disulfide ((CH₃)₂S₂) and 1-pentanethiol (C₅H₁₂S). Temperature and time conditions of SPME extraction were optimised and the method was validated, with good linearity in a calibration range between 0.1 and 1000 μg m⁻³. Method detection limits ranged between 0.01 and 0.08 μg m⁻³ and method quantification limits were between 0.10 and 0.25 μg m⁻³, allowing real samples taken from several different areas of a sewage treatment plant to be analysed. Repeatability of the method between samples went from 5.6% for pentanethiol up to 14.2% for carbon disulfide, and concentrations of total target compounds were found between 18 and 529 μg m⁻³, depending on the sampling site.     

Determination of elemental sulfur in coal by gas chromatography-mass spectrometry

A method for the determination of S0 in coal based on the extraction with cyclohexane with subsequent quantitative analysis of elemental sulfur in the extract by GC/MS is described. The quantity of elemental sulfur was determined in four coal samples with different distribution of sulfur forms. The effect of solvent and extraction time on the efficiency of sulfur removal was studied. The elemental sulfur extracted from coal occurred in the form of S6, S7 and S8. Calibration solutions were prepared from freshly recrystalized elemental sulfur. It was found that the injection temperature has a crucial influence on the m/z 64 ion chromatogram.     

电子制冷预浓缩-双柱气相色谱-质谱/氢火焰检测器法测定空气中104种挥发性有机物

基于吸附剂辅助电子制冷预浓缩技术，建立了多维切割双柱气相色谱-质谱/氢火焰离子化检测器（GC-MS/FID）同时测定环境空气中104种挥发性有机物（VOCs）的方法。将采集于苏玛罐中的环境空气样品在配有吸附剂的电子制冷预浓缩系统中富集、脱附、除水、除CO₂和浓缩，然后通过GC-MS/FID的多维切割单元将C₂~C₃组分和C₄~C₁₂组分分别引入PLOT柱和InterCap-624柱进行分离。C₂~C₃组分用FID检测，以保留时间定性、外标法定量；C₄~C₁₂组分采用电子轰击离子源质谱检测，以保留时间和特征离子定性、内标法定量。考察了冷阱吸附剂种类、辅助压力控制单元压力设置、双柱切换时间切割点等参数对分析结果的影响，优化了GC-MS/FID条件，并评估了在此优化条件下的方法性能。104种VOCs在0.0446~0.892 μmol/m³范围内线性关系良好，相关系数（r）为0.9984~0.9999，对0.0446 μmol/m³和0.223 μmol/m³水平的混合标准气体重复6次进样，平均回收率为86.4%~116.1%，相对标准偏差为0.9%~11.3%；方法的检出限为0.145~1.90 μg/m³，定量限为0.435~5.70 μg/m³。该法稳定性好，灵敏度高，操作简便，可用于环境空气中104种VOCs的测定。     

Sampling and analysis of volatile organic compounds in bovine breath by solid-phase microextraction and gas chromatography-mass spectrometry

A relatively noninvasive method consisting of a face mask sampling device, solid-phase microextraction (SPME) fibers, and a gas chromatography-mass spectrometry (GC-MS) for the identification of volatile organic compounds (VOCs) in bovine breath was developed. Breath of three morbid steers with respiratory tract infections and three healthy steers were sampled seven times in 19 days for 15 min at each sampling. The breath VOCs adsorbed on the divinylbenzene (DVB)-Carboxen-polydimethyl siloxane (PDMS) 50/30 microm SPME fibers were transported to a laboratory GC-MS system for separation and identification with an in-house spectral library of standard chemicals. A total of 21 VOCs were detected, many of them for the first time in cattle breath. Statistical analyses using Chi-square test on the frequency of detection of each VOC in each group was performed. The presence of acetaldehyde (P < or = 0.05) and decanal (P < or = 0.10) were associated more with clinically morbid steers while methyl acetate, heptane, octanal, 2,3-butadione, hexanoic acid, and phenol were associated with healthy steers at P < or = 0.10. The results suggest that noninvasive heath screening using breath analyses could become a useful diagnostic tool for animals and humans.