便携式GC-MS在应急监测中的应用

建立了便携式GC-MS测定空气和水体中挥发性有机物(VOCs)的方法,能快速、有效地对空气中37种和水体中54种挥发性有机物进行现场定性和定量。具有相关性好、检出限低、精密度好、准确度高的特点,适用于空气和水体中挥发性有机物的应急监测工作。     

Screening volatile organic compounds (VOCs) emissions from five marine phytoplankton species by head space gas chromatography/mass spectrometry (HS-GC/MS)

Five marine cosmopolitan phytoplankton species namely; Calcidiscus leptoporus, Emiliania huxleyi, Phaeodactylum tricornutum, Chaetoceros neogracilis and Dunaliella tertiolecta were screened for emissions of selected VOCs using head space gas chromatography/mass spectrometry (HS-GC/MS) in single ion mode. The VOCs investigated included isoprene and various halogenated compounds. Among the different algae groups, the two diatoms Ch. neogracilis and P. tricornutum were the strongest emitters of methyl bromide (CH3Br), and Ch. neogracilis was the strongest emitter of isoprene. Furthermore, we present evidence that several chlorinated organic compounds, normally considered as anthropogenic, can be produced from marine phytoplankton (namely chloroform, dichloromethane, trichloroethylene, tetrachloroethylene, chlorobenzene and dichlorobenzene).     

食品企业周边空气中异味挥发性有机物测定方法比较

以1个典型食品生产企业(酱菜厂)周边的异味挥发性有机物监测为例,介绍了罐采样-GC/MS、便携式GC/MS、SPME-GC/MS以及SPME-异味分析系统等4种监测方法的实际应用,从定性、定量监测结果等方面,比较了4种监测方法的特点。罐采样-GC/MS、便携式GC-MS 2种方法适用于定性、定量检测,在有标准样品的前提下,定量结果总体可比;SPME-GC/MS以及SPME-异味分析系统2种方法更适用于定性检测。     

Development of a solid phase microextraction (SPME) method for the sampling of VOC traces in indoor air

Solid-phase microextraction (SPME) was studied for the measurement of volatile organic compounds (VOCs) in indoor air. An adsorptive PDMS/Carboxen fibre was used and an analytical methodology was developed in order to overcome competitive adsorption. Kinetics and adsorption isotherms were investigated for different sample volumes and model compounds. In order to evaluate competitive adsorption on the fibre, these compounds were studied alone and in mixture. From the results obtained, the operating conditions allowing co-adsorption of the target compounds were determined: the air sample is enclosed in a 250 mL glass bulb where the SPME fibre is exposed until adsorption equilibrium. This procedure was combined with GC/MS analysis for the identification and quantification of VOCs in indoor air. The performances were determined by using a standard gas containing 10 VOCs representative of indoor environments (acetaldehyde, acetone, BTX, alpha-pinene, trichloroethylene, alkanes). The detection limits were determined in single ion monitoring mode and for a signal to noise ratio of 3. Except acetaldehyde (6 microg m(-3)), they are all below 0.5 microg m(-3). Calibration curves are linear up to 10 micromol m(-3) for all the compounds with good correlation coefficients (above 0.99). The reproducibility ranges from 6 to 12% according to the compound. The methodology was then applied to the comparison of the VOCs content in classrooms of two different schools.     

VOCs在线监测系统与SUMMA罐采样-气质联用法的比对分析

将挥发性有机污染物在线监测系统与实验室内SUMMA罐采样气质联用法(GC-MS)的挥发性有机物分析进行了标准气体和实际空气样品的分析比对,并对偏差原因作分析,提出在线监测系统的维护建议。结果表明,挥发性有机物在线监测系统的监测结果与实验室方法有一定的可比性,可用于大气中挥发性有机污染物的在线监测。     

Comprehensive screening and priority ranking of volatile organic compounds in Daliao River,China

An analytical strategy for comprehensive screening of target and non-target volatile organic compounds (VOCs) in surface water was developed, and it was applied to the analysis of VOCs in water samples from Daliao River. The target VOCs were quantified using purge and trap-gas chromatography-mass spectrometry (P&T-GC/MS). Among 20 water samples, 34 VOCs were detected at least once. For the screening of non-target VOCs, the double distillation apparatus was used for the pre-concentration of VOCs prior to P&T-GC/MS analysis. Subsequently, deconvolution software and NIST mass spectral library were applied for the identification of the non-target compounds. A total of 17 non-target VOCs were identified. The most frequently detected VOCs (detection frequencies >80 %) included toluene, benzene, naphthalene, 1,2-dichloroethane, 1,1,2-trichloroethane, and methyl tert-butyl ether. The distribution of VOCs obviously varied according to the sampling sites. The total concentrations of VOCs in water samples collected from the heavily industrialized cities (Anshan and Liaoyang) and the busy port city (Yingkou) were relatively high. The top ten priority VOCs, including naphthalene, 1,2-dichloroethane, o-xylene, 1,3-dichlorobenzene, tetrachloroethene, 1,2-dichlorobenzene, 1,2,4-trichlorobenzene, ethylbenzene, m-xylene, and p-xylene, were obtained by the ranking of the detected VOCs according to their occurrence and ecological effects. These compounds should be given more attention in monitoring and drainage control strategies.     

水中异味物质分析方法研究进展

介绍了水体异味现象及异味物质组分,综述了闭环捕集、吹扫捕集、液液萃取、固相萃取、固相微萃取、搅拌棒吸附萃取等样品前处理技术。指出气相色谱/质谱联用具有很强的分离和定性定量能力,与上述前处理技术联用是目前水体异味物质分析应用最广泛的方法。     

预冷冻浓缩系统与气相色谱-质谱联用测定空气中挥发性有机物

采用预冷冻浓缩系统和气相色谱-质谱联用,建立了测定空气中39种挥发性有机物的分析方法,该法用苏玛罐或Tedlar气袋采集空气样品经-160℃液氮预冷冻浓缩后,用GC-MS检测.该方法采样简便,灵敏度、准确度高,已应用于室内空气和环境空气的测定,取得满意的结果.     

Development and comparison of methods using MS scan and selective ion monitoring modes for a wide range of airborne VOCs

Adsorbent sampling with analysis by thermal desorption, gas chromatography and mass spectrometry (TD/GC/MS) offers many advantages for volatile organic compounds (VOCs) and thus is increasingly used in many applications. For environmental samples and other complex mixtures, the MS detector typically is operated in the scan mode to aid identification of co-eluting compounds. However, scan mode does not achieve the optimal sensitivity, thus compounds occurring at low concentrations may not be detected. This paper develops and evaluates the application of a more sensitive TD/GC/MS method using selective ion monitoring (SIM) that is applicable to VOC mixtures found in ambient and indoor air. Based on toxicity and prevalence, 94 VOCs (including terpenes, aromatic, halogenated and aliphatic compounds) were selected as target compounds. Two analytical methods were developed: a conventional full scan method for ions from 29 to 270 m/z; and a SIM method using 16 time windows and different ions selected for the compounds in each window. Both methods used the same Tenax GR adsorbent sampling tubes, TD and GC parameters, and target and qualifier ions. Laboratory tests determined calibrations, method detection limits (MDLs), precisions, recoveries and storage stability. Field tests compared scan and SIM mode analyses for duplicate samples of indoor air in 51 houses and outdoor air at 41 sites. Statistical analyses included the development of error/precision models. The laboratory tests showed that most compounds demonstrated excellent precision (<10% for concentrations exceeding approximately 0.5 microg m(-3)), good linearity, near identical calibrations for scan and SIM modes, a wide dynamic range (up to 1500 microg m(-3)), and negligible storage losses after 1 month (7 compounds showed moderate losses). SIM mode MDLs ranged from 0.004 to 0.27 microg m(-3), representing a modest (1.1 to 22-fold) improvement compared to scan mode. However, in field tests the SIM method detected significantly more compounds (e.g., styrene and chloroform). Error models fit most compounds and allow quantification of errors at selected percentiles. Overall, while the new SIM method is somewhat time-consuming to develop, it offers greater sensitivity and maintains the high selectivity of traditional scan methods.     

Comparison of 24 h averaged VOC monitoring results for residential indoor and outdoor air using Carbopack X-filled diffusive samplers and active sampling--a pilot study

Analytical results obtained by thermal desorption GC/MS for 24 h diffusive sampling of 11 volatile organic compounds (VOCs) are compared with results of time-averaged active sampling at a known constant flow rate. Air samples were collected with co-located duplicate diffusive sampling tubes and one passivated canister. A total of eight multiple-component sampling events took place at fixed positions inside and outside three private homes. Subsequently, a known amount of sample air was transferred from the canister to an adsorbent tube for analysis by thermal desorption GC/MS. Results for the 11 most prevalent compounds--Freon 11, 1,3-butadiene, benzene, toluene, tetrachloroethene, ethylbenzene, m,p-xylene, o-xylene, 4-ethyltoluene, 1,3,5-trimethylbenzene, and p-dichlorobenzene--show that the ratio of average study values (diffusive sampling to active sampling) is 0.92 with 0.70 and 1.14 extreme ratios. Absolute percent difference for duplicate samples using diffusive sampling was <10% for the four most prevalent compounds. Agreement between the two sampling approaches indicates that the prediction of approximately constant diffusive sampling rates based on previous laboratory studies is valid under the field conditions.     

Determination of synthetic musk compounds in sewage biosolids by gas chromatography/mass spectrometry

A review of sewage sludge regulations and land application practices by the United States National Research Council (2002) recommended development of improved analytical techniques to adequately identify and quantify new chemical contaminants, such as synthetic musk compounds in Class A sewage sludge (i.e., biosolids). This prompted the development of a rugged analytical method using gas chromatography coupled to mass spectrometry to detect this group of organic pollutants in biosolids. In this paper, the term "biosolids" is used interchangeably with "sewage sludge", which is defined in the regulations and used in the statue (Clean Water Act). Samples of Class A biosolids obtained from sewage treatment plants in Los Angeles, California, the City of Las Vegas, Nevada, and also in the form of a commercial fertilizer, were extracted using pressurized liquid extraction technique, subjected to gel permeation chromatography clean-up, and analyzed by GC/MS using the selected ion monitoring mode. The method developed has the potential to detect synthetic musk compounds in complex matrices, may provide accurate data useful in human health and environmental risk assessment, and may be useful in determining the efficacy of municipal sewage treatment plants for removing synthetic musk compounds.     

Simultaneous analysis of endosulfan, chlorpyrifos, and their metabolites in natural soil and water samples using gas chromatography-tandem mass spectrometry

Analysis of endosulfan, chlorpyrifos, and their nonpolar metabolites in extracts from environmental aqueous and soil samples was performed using a gas chromatography-tandem mass spectrometry (GC–MS/MS) technique. Full-scan GC–MS analysis showed poor sensitivity for some of the metabolites (endodiol and endosulfan ether). A multisegment MS/MS method was developed and MS/MS parameter isolation time, excitation time, excitation voltage, and maximum excitation energy were optimized for chosen precursor ions to enhance selectivity and sensitivity of the analysis. The use of MS/MS with optimized parameters quantified analytes with significantly higher accuracy, and detection limits were lowered to ~1/6th compared with the full-scan method. Co-eluting compounds, chlorpyrifos and chlorpyrifos oxon, were also analyzed successfully in the MS/MS mode by choosing exclusive precursor ions. Analysis of soil and water phase samples from contaminated soil slurry bioreactors showed that the MS/MS method could provide more reliable estimates of these pesticide and metabolites (especially those present in low concentrations) by annulling interferences from soil organic matter.     

气相色谱/质谱(GC/MS)联用在我国环境监测中的应用

从系统分析和有机污染分析等方面出发 ,概述了气相色谱 质谱 (GC MS)联用在我国大气、水质、土壤等环境监测中所取得的重要成果 ,例如可测定多环芳烃、硝基多环芳烃、多氯二苯并二、多氯二苯并呋喃、农药、酚类、多氯联苯、恶臭、有机酸、有机硫化合物和苯系物、卤代烃、氯苯类等挥发性化合物 ,以及多组分有机污染物。     

Evaluation of the effect of different sampling time periods and ambient air pollutant concentrations on the performance of the Radiello diffusive sampler for the analysis of VOCs by TD-GC/MS

The effect of different sampling exposure times and ambient air pollutant concentrations on the performance of Radiello? samplers for analysis of volatile organic compounds (VOCs) is evaluated. Quadruplicate samples of Radiello? passive tubes were taken for 3, 4, 7 and 14 days. Samples were taken indoors during February and March 2010 and outdoors during July 2010 in La Canonja (Tarragona, Spain). The analysis was performed by automatic thermal desorption (ATD) coupled with capillary gas chromatography (GC)/mass spectrometry detection (MS). The results show significant differences (t-test, p < 0.05) between the amounts of VOCs obtained from the sum of two short sampling periods and a single equivalent longer sampling period for 65% of all the data. 17% of the results show significantly larger amounts of pollutant in the sum of two short sampling periods. Back diffusion due to changes in concentrations together with saturation and competitive effects between the compounds during longer sampling periods could be responsible for these differences. The other 48% of the results that are different show significantly larger amounts in the single equivalent longer sampling period. The remaining 35% of the results do not show significant differences. Although significant differences are observed in the amount of several VOCs collected over two shorter sampling intervals compared to the amount collected during a single equivalent longer sampling period, the ratios obtained are very close to unity (between 0.7 and 1.2 in 75% of cases). We conclude that Radiello? passive samplers are useful tools if their limitations are taken into account and the manufacturer's recommendations are followed.     

气相色谱-质谱法测定大气中98种挥发性有机物

通过色谱-质谱联用法(简称GC-MS),利用低温冷阱技术对大气中的VOCs进行浓缩富集,然后经过加热解吸分别至毛细管色谱柱和FID检测器及MS检测器,对大气中98种挥发性有机化合物(VOCs)进行分离、定性、定量测定。方法检出限为0.008×10-9~0.100×10-9(V/V);线性相关系数的平方值为0.992 7~1,相对标准偏差为4.0%~20.2%,总体标准偏差为0.154 2~0.952 1。     

吹扫捕集-气相色谱质谱法分析土壤和沉积物中挥发性有机物

采用吹扫捕集-气相色谱质谱法对土壤和沉积物中挥发性有机物进行分析,优化了实验条件,所有物质的相对标准偏差小于5.0％,土壤样回收率在78.2％ ～99.8％之间,沉积物样的回收率在55.2％～95.2％之间.     

国内外VOCs排放管理控制历程

介绍了挥发性有机污染物(VOCs)的定义、来源和危害,回顾了国内外VOCs监测技术、观测浓度、排放标准及规范,概括了欧美等发达国家宏观层面上的VOCs排放管理控制战略、经验及效果.建议我国建立VOCs在线监测网络,开展VOCs排放清单计算工作,进一步加强机动车尾气排放VOCs控制,初步制定宏观层面的VOCs总体控制战略...     

石化行业VOCs泄漏检测与修复技术的发展现状与展望

针对石化行业挥发性有机物(VOCs)污染现状,总结了近年来我国国家层面和地方颁布的有关VOCs管控的法律法规及相关标准。通过调研石化行业现阶段VOCs控制的实际情况,总结了目前主要的控制技术,以及适合我国企业VOCs排放源的监测技术。在综合分析的基础上,提出了大力推进清洁生产、全面推行泄漏检测与修复(LDAR)计划、加强有组织工艺废气治理、严格控制储存与装卸损失、强化污水系统逸散废气治理、加强非正常工况污染控制等建议。     

Using a Composite Membrane for Enhanced Sensitivity and Faster Response in On-line Membrane Extraction Microtrap Gas Chromatography

On-line membrane extraction microtrap (OLMEM) gas chromatography was used for continuous monitoring of volatile organic compounds (VOCs) in water. The aqueous sample flowed through tubular membrane and the VOCs selectively permeated through it. The permeated VOCs were stripped by a carrier gas and transported to a microtrap. The microtrap retained and concentrated the analytes before injecting into a GC. In this study, the performance of a composite membrane was compared with that of a conventional silicone membrane. The advantages of using the composite membrane were higher extraction efficiency and shorter response time. Extraction efficiencies as high as 95% were obtained for compounds such as toluene and trichloroethane.     

Influence of Relative Humidity and Ozone on the Sampling of Volatile Organic Compounds on Carbotrap/Carbosieve Adsorbents

By using a dynamic dilution system, the atmospheric measurement of 11 selected toxics VOCs (ethylene, acetylene, propene, 1-butene, 1,3-butadiene, 1-pentene, 1-hexene, benzene, toluene, ethylbenzene, m+p-xylene) from the list WHO of 1996 and TO-14 method of US EPA by preconcentration by thermal desorption (TD), analysis by gas chromatography (GC), identification and quantification with a flame ionisation detector (FID) was developed and validated in term of metrology, especially the techniques of sampling of these VOCs with adsorbents cartridges "Air Toxics" when used with an "UMEG sampler" equipped in the inlet with a nafion membrane. In particular the influence of climatic conditions (temperature and relative humidity) and the influence of chemical factors like ozone, on the representativity of sampling were studied. Experiments made with various humidities showed that the addition of a nafion membrane in the inlet of the sampling system was required. Without this membrane, losses of compounds were observed for RH >50%. With this membrane, storage for 2 weeks in a refrigerator, as for canisters, did not induce a loss of compounds. No significative decrease of concentrations of the studied VOCs after 14 days storage, which are known to react with ozone, were observed with an ozone concentrations of 55 ppb. One explanation is that nafion membrane, placed in the inlet of the sampler, will neutralize ozone before entering the sampling tubes. This observation is in accordance with literature which states that the sampling of VOCs on Carbotrap cartridges without ozone scrubber induce a loss of compounds.