空气中挥发性有机物(VOCs) 的监测方法研究

建立了热脱附仪和气相色谱-质谱联用测定室内空气和环境空气中35种挥发性有机污染物的分析方法,方法的最低检出限为0.1～0.9μg/m3, 20μg/m3挥发性有机物标准经6次的重复测定,其相对标准偏差小于8.4%.该方法已用于室内空气和环境空气的测定,取得令人满意的结果.     

Indoor and outdoor concentrations of fine particles, particle-bound PAHs and volatile organic compounds in Kaunas, Lithuania

This complex study presents indoor and outdoor levels of air-borne fine particles, particle-bound PAHs and VOCs at two urban locations in the city of Kaunas, Lithuania, and considers possible sources of pollution. Two sampling campaigns were performed in January-February and March-April 2009. The mean outdoor PM(2.5) concentration at Location 1 in winter was 34.5 ± 15.2 μg m(-3) while in spring it was 24.7 ± 12.2 μg m(-3); at Location 2 the corresponding values were 36.7 ± 21.7 and 22.4 ± 19.4 μg m(-3), respectively. In general there was little difference between the PM concentrations at Locations 1 and 2. PM(2.5) concentrations were lower during the spring sampling campaign. These PM concentrations were similar to those in many other European cities; however, the levels of most PAHs analysed were notably higher. The mean sum PAH concentrations at Locations 1 and 2 in the winter campaign were 75.1 ± 32.7 and 32.7 ± 11.8 ng m(-3), respectively. These differences are greater than expected from the difference in traffic intensity at the two sites, suggesting that there is another significant source of PAH emissions at Location 1 in addition to the traffic. The low observed indoor/outdoor (I/O) ratios indicate that PAH emissions at the locations studied arise primarily from outdoor sources. The buildings at both locations have old windows with wooden frames that are fairly permissive in terms of air circulation. VOC concentrations were mostly low and comparable to those reported from Sweden. The mean outdoor concentrations of VOC's were: 0.7 ± 0.2, 3.0 ± 0.8, 0.5 ± 0.2, 3.5 ± 0.3, and 0.2 ± 0.1 μg m(-3), for benzene, toluene, ethylbenzene, sum of m-, p-, o-xylenes, and naphthalene, respectively. Higher concentrations of VOCs were observed during the winter campaign, possibly due to slower dispersion, slower chemical transformations and/or the lengthy "cold start" period required by vehicles in the wintertime. A trajectory analysis showed that air masses coming from Eastern Europe carried significantly higher levels of PM(2.5) compared to masses from other regions, but the PAHs within the PM(2.5) are of local origin. It has been suggested that street dust, widely used for winter sanding activities in Eastern and Central European countries, may act not only as a source of PM, but also as source of particle-bound PAHs. Other potential sources include vehicle exhaust, domestic heating and long-range transport.     

运用热脱附/GC/MS分析研究室内空气中TVOC浓度及种类分布

利用热脱附/GC/MS联用技术定性、定量(半定量)分析了多组有代表性的室内空气样品。结果表明,室内空气挥发性有机气体的主要成分是苯系物、烃类、醛酮类、酯类等;装修后3个月内的家居室内空气中的苯25%超标,甲苯58%超标,二甲苯79%超标,TVOC 100%超标;一年后,仅TVOC还有11%的超标。办公室情况类似。     

Long-term measurement of volatile organic compounds in ambient air by canister-based one-week sampling method

A canister-based 1 week sampling method using a mechanical flow controller and a 6 L fused-silica-lined canister was evaluated for the long-term measurement of 47 VOCs in ambient air at pptv (volume/volume) to ppbv levels by use of a three-stage preconcentation method followed by GC-MS analysis. The GC conditions were initially optimized for complete separations of several pptv-level VOCs (e.g. vinyl chloride, 1,3-butadiene, acrylonitrile, 1,2-dichloroethane and chloroform) in ambient air because the selected ions are easily interfered with by coexisting C4-, C5-hydrocarbons and analytes presented at ppbv levels. Thirty-four VOCs determined by the 1 week and 24 h sampling method in December 16-22 (2002) had concentrations of 6.0-15000 pptv per compound. Concentrations of 28 VOCs (including polar VOCs (e.g. methyl isobutyl ketone and butyl acetate)) obtained by the method were approximately equal to the mean values calculated from 24 h sampling (< +/- 10% deviation). Six VOCs that had low concentrations of 6.0-43 pptv showed more than +/- 10% deviation. Thirteen VOCs were not detected during the entire sampling period. The effect of relative humidity or ozone for the specific VOCs (e.g. MIBK, butyl acetate, vinyl chloride, 1,3-butadiene and styrene) was negligible.     

Compact semi-automatic incident sampler for personal monitoring of volatile organic compounds in occupational air

Suddenly occurring and time limited chemical exposures caused by unintended incidents might pose a threat to many workers at various work sites. Monitoring of exposure during such occasional incidents is challenging. In this study a compact, low-weight and personal semi-automatic pumped unit for sampling of organic vapor phase compounds from occupational air during sporadic and suddenly occurring incidents has been developed, providing simple activation by the worker potentially subjected to the sudden occurring exposures when a trained occupational hygienist is not available. The sampler encompasses a tube (glass or stainless steel) containing an adsorbent material in combination with a small membrane pump, where the adsorbent is capped at both ends by gas tight solenoid valves. The sampler is operated by a conventional 9 V battery which tolerates long storage time (at least one year), and is activated by pulling a pin followed by automatic operation and subsequent closing of valves, prior to shipping to a laboratory. The adjustable sampling air flow rate and the sampling time are pre-programmed with a standard setting of 200 mL min(-1) and 30 min, respectively. The average airflow in the time interval 25-30 min compared to average airflow in the interval 2-7 min was 92-95% (n = 6), while the flow rate between-assay precisions (RSD) for six different samplers on three days each were in the range 0.5-3.7%. Incident sampler recoveries of VOCs from a generated VOC atmosphere relative to a validated standard method were between 95 and 102% (+/-4-5%). The valves that seal the sampler adsorbent during storage have been shown to prevent an external VOC atmosphere (500 mg m(-3)) to enter the adsorbent tube, in addition to that the sampler adsorbent is storable for at least one month due to absence of ingress of contaminants from internal parts. The sampler was also suitable for trapping of semi-volatile organophosphates.     

Levels, sources, and health risks of carbonyls in residential indoor air in Hangzhou, China

Concentrations of formaldehyde, acetaldehyde, acetone, propionaldehyde, i-pentanal, and butyraldehyde in residential indoor air in Hangzhou were determined. The mean concentration of the total carbonyl compounds in summer was 222.6 μg/m³, higher than that in winter (68.5 μg/m³). The concentration of a specific carbonyl in indoor air was higher than the outdoor air measurement, indicating the release of carbonyls from the indoor sources. Formaldehyde and acetone were the most abundant carbonyls detected in summer and winter, respectively. Multiple regression analysis indicated that carbonyl concentrations in residential indoor air depended on the age of decoration and furniture, as well as their concentrations in outdoor air. In addition, a primary estimation showed that the health risks of carbonyls in summer were higher than those in winter.     

某乡镇大气中毒害挥发性有机物的研究

对经济较发达的某乡镇大气的毒害挥发性有机化合物研究表明,该镇城区及其较发达的乡村已受到一定程度的有机污染,大气中主要存在苯系物、萘、氯代烃等毒害挥发性有机化合物.个别样品的苯乙烯含量高达14.50μg/m3,此值已超过中国居住区最高容许浓度.     

A comparison of sampling and analysis methods for low-ppbC levels of volatile organic compounds in ambient air

A carefully designed study was conducted during the summer of 1998 to collect samples of ambient air by canisters and compare the analysis results to direct sorbent preconcentration results taken at the time of sample collection. Thirty-two 1 h sample sets were taken, each composed of a "near-real-time" sample analyzed by an autoGC-MS XonTech 930/Varian Saturn 2000 system, and Summa and Silco canisters. Hourly total non-methane organic carbon (TNMOC), ozone, and meteorological measurements were also made. Each canister was analyzed on the autoGC-MS system for a target list of 108 volatile organic compounds (VOCs) and on a manual cryosampling GC-FID system. Comparisons were made between the collection and analysis methods. Because of the low sample loading (150-250 ppbC TNMOC), these comparisons were a stringent test of sample collection and analysis capabilities. The following specific conclusions may be drawn from this study. Reasonable precision (within 15% mean difference of duplicate analyses from the same canister) can be obtained for analyses of target VOCs at low-ppbC concentrations. Relative accuracy between the GC-MS and GC-FID analysis methods is excellent, as demonstrated by comparisons of analyses of the same canisters, if measurements are sufficiently above the detection limits. This is especially significant as the GC-MS and GC-FID were independently calibrated. While statistically significant differences may be observed between the results from canister and near-real-time samples, the differences were generally small and there were clear correlations between the canister results and the near-real-time results. Canister cleanliness limits detection below the EPA Method TO-14 acceptance standard of 0.2 ppbv (0.2-2 ppbC for target analytes).     

A novel approach to evaluation of adsorbents for sampling indoor volatile organic compounds associated with symptom reports

This article addresses problems that complicate attempts to compare methods when several factors may be associated with an effect, but it is not known which factors are relevant. Chemicals that may contribute to 'sick building syndrome' (SBS), and thus should be sampled in investigations of SBS, are not currently known. A study was undertaken to compare the utility of three adsorbents (Carbopack B, Chromosorb 106 and Tenax TA) for detecting differences in personal chemical exposure to volatile organic compounds in indoor air, between persons with and without SBS symptoms (cases and controls). On the basis of office workers' responses to a questionnaire, 15 cases and 15 controls were chosen. They simultaneously carried diffusive samplers with adsorbents during a week at work, and the acquired samples were analysed by gas chromatography/mass spectrometry (GC/MS). The adsorbents were then compared in terms of their ability to separate cases and controls in partial least square discriminant analysis (PLS-DA) models. This method of comparison takes into account detected differences in chemical exposure between cases and controls measured with the different adsorbents. Tenax TA gave the best PLS-DA models for separating cases and controls, but a combination of measurements with Tenax TA and Carbopack B gave better PLS-DA models than models based on measurements from either adsorbent alone. Adding measurements from Chromosorb 106 did not improve the results.     

The use of semipermeable membrane devices as passive samplers to determine persistent organic compounds in indoor air

In the study reported here semipermeable membrane devices (SPMDs) were used to sample 28 PAHs and 19 PCBs in the gas phase in 15 single-family houses located in an area where domestic wood burning is widespread. Eight of the households used wood burning appliances whereas the others used other systems for residential heating. Most of the studied compounds were found in the houses: the PAHs at levels that were similar to or slightly higher than published SPMD-sampled levels for background or urban sites in Sweden, and the PCBs at levels that were somewhat lower than those recently found in both indoor and outdoor urban locations. A principal component analysis revealed that wood-burning heating systems may contribute to PAHs in indoor air. The sources may be emissions indoors or penetration from outdoors. The convenience of SPMD technology facilitates its use for semi-quantitative screening and monitoring of various persistent organic compounds indoors in dwellings and working environments.     

Soil sampling and analysis for volatile organic compounds

Concerns over data quality have raised many questions related to sampling soils for volatile organic compounds (VOCs). This paper was prepared in response to some of these questions and concerns expressed by Remedial Project Managers (RPMs) and On-Scene Coordinators (OSCs). The following questions are frequently asked:

1. Is there a specific device suggested for sampling soils for VOCs?
2. Are there significant losses of VOCs when transferring a soil sample from a sampling device (e.g., split spoon) into the sample container?
3. What is the best method for getting the sample from the split spoon (or other device) into the sample container?
4. Are there smaller devices such as subcore samplers available for collecting aliquots from the larger core and efficiently transferring the sample into the sample container?
5. Are certain containers better than others for shipping and storing soil samples for VOC analysis?
6. Are there any reliable preservation procedures for reducing VOC losses from soil samples and for extending holding times?

Guidance is provided for selecting the most effective sampling device for collecting samples from soil matrices. The techniques for sample collection, sample handling, containerizing, shipment, and storage described in this paper reduce VOC losses and generally provide more representative samples for volatile organic analyses (VOA) than techniques in current use. For a discussion on the proper use of sampling equipment the reader should refer to other sources (Acker, 1974; U.S. EPA, 1983; U.S. EPA, 1986a). Soil, as referred to in this report, encompasses the mass (surface and subsurface) of unconsolidated mantle of weathered rock and loose material lying above solid rock. Further, a distinction must be made as to what fraction of the unconsolidated material is soil and what fraction is not. The soil component here is defined as all mineral and naturally occurring organic material that is 2 mm or less in size. This is the size normally used to differentiate between soils (consisting of sands, silts, and clays) and gravels. Although numerous sampling situations may be encountered, this paper focuses on three broad categories of sites that might be sampled for VOCs:

1. Open test pit or trench.
2. Surface soils (<5 ft in depth).
3. Subsurface soils (>5 ft in depth).

     

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.     

Elevated concentrations of endotoxin in indoor air due to cigarette smoking

Exposure to environmental tobacco smoke (ETS) is an important worldwide public health issue. The present study demonstrates that cigarette smoke can be a major source of endotoxin (lipopolysaccharide, LPS) in indoor environments. Gas-chromatography/mass-spectrometry was used to determine 3-hydroxy fatty acids as markers of endotoxin in air-borne house dust in homes of smokers and non-smokers. Air concentrations of endotoxin were 4-63 times higher in rooms of smoking students than in identical rooms of non-smoking students. The fact that cigarette smoke contains large amounts of endotoxin may partly explain the high prevalence of respiratory disorders among smokers and may also draw attention to a hitherto neglected risk factor of ETS.     

An evaluation of a fast sampling procedure for the trace analysis of volatile organic compounds in ambient air

This study deals with the evaluation of a fast method for sampling of volatile organic compounds in ambient air. Special bags made of an inert material are used together with a large handpump which allows a sampling of one liter per second. After the sampling, the pollutants are concentrated by adsorption on Tenax and transfered by heat desorption, to a small capillary precolumn cooled with liquid nitrogen, or directly trapped on the precolumn. The suitability of this technique was evaluated by sampling complex synthetic mixtures of known concentration and composition, after which the samples were submitted to a series of operations such as transport, aging, changing of the humidity, heating and cooling, irradiation, etc. Changes in the original mixtures, caused by adsorption, diffusion, chemical or photochemical reactions were investigated by GC-MS analysis. The results of the study show that under certain conditions the samples can be preserved for a rather long period of time without noticeable changes in composition. However for certain compounds, severe quantitative losses occur after one day storage. Finally a practical application of this method is described in a recent case of strong odour annoyance by a chemical plant in the north of Belgium.     

Characterizations of volatile organic compounds during high ozone episodes in Beijing,China

Air samples were collected in Beijing from June through August 2008, and concentrations of volatile organic compounds (VOCs) in those samples are here discussed. This sampling was performed to increase understanding of the distributions of their compositions, illustrate the overall characteristics of different classes of VOCs, assess the ages of air masses, and apportion sources of VOCs using principal compound analysis/absolute principal component scores (PCA/APCS). During the sampling periods, the relative abundance of the four classes of VOCs as determined by the concentration-based method was different from that determined by the reactivity approach. Alkanes were found to be most abundant (44.3–50.1%) by the concentration-based method, but aromatic compounds were most abundant (38.2–44.5%) by the reactivity approach. Aromatics and alkenes contributed most (73–84%) to the ozone formation potential. Toluene was the most abundant compound (11.8–12.7%) during every sampling period. When the maximum incremental reactivity approach was used, propene, toluene, m,p-xylene, 1-butene, and 1,2,4-trimethylbenzene were the five most abundant compounds during two sampling periods. X/B, T/B, and E/B ratios in this study were lower than those found in other cities, possibly due to the aging of the air mass at this site. Four components were extracted from application of PCA to the data. It was found that the contribution of vehicle exhaust to total VOCs accounted for 53% of VOCs, while emissions due to the solvent use contributed 33% of the total VOCs. Industrial sources contributed 3% and biogenic sources contributed 11%. The results showed that vehicle exhausts (i.e., unburned vehicle emissions + vehicle internal engine combustion) were dominant in VOC emissions during the experimental period. The solvent use made the second most significant contribution to ambient VOCs.     

Calibration of two passive air sampler configurations for monitoring concentrations of hexabromocyclododecanes in indoor air

While polyurethane foam (PUF) disk passive air samplers are employed increasingly to monitor persistent organic pollutants in indoor air, they essentially sample only the vapour phase. As a previous investigation of the vapour : particle phase partitioning of hexabromocyclododecanes HBCDs in (outdoor) air reported them to be present largely in the particulate phase, we monitored three offices using active air samplers. In each, approximately 65% of HBCDs were present in the vapour phase, suggesting PUF disk passive samplers are suitable for monitoring HBCDs in indoor air. Concentrations in the three offices (239-359 pg Sigma HBCD m(-3)) exceed substantially those reported in outdoor air from the United States (2.1-11 pg Sigma HBCD m(-3)), but are in line with outdoor air from Stockholm. The relative abundance of the three principal diastereomers in office air was closer to that found in technical HBCD formulations (i.e. predominantly gamma-HBCD) than in most US outdoor air samples. Time integrated air concentrations of alpha-, beta-, and gamma-HBCD were obtained for an office using a low volume sampler operated over a 50 d period alongside PUF disk samplers. This calibration exercise yielded the following passive air sampling rates for both a fully- and part-sheltered PUF disk sampler design: for alpha-, beta-, and gamma-HBCD, 0.87, 0.89, and 0.91 m3 d(-1) respectively (fully-sheltered) and 1.38, 1.54, and 1.55 m3 d(-1) respectively (part-sheltered). Deployment of the part-sheltered configuration yielded concentrations approximately 35% lower than those obtained using a high volume sampler, consistent with PUF disk samplers measuring primarily the vapour phase.     

Investigation and assessment of volatile organic compounds in water sources in China

456 water samples collected from 152 water sources in 2006 were analyzed for 21 volatile organic compounds (VOCs). Concentrations of 21 VOCs ranged from below method detection limits of the laboratory to 7.65 ??g/L (toluene), but seldom exceeded the concentration limits set in the National Drinking Water Quality Standards (GB5749-2006) or the National Environmental Quality Standards for Surface Water (GB3838-2002) of China. Of the 21 individual VOCs analyzed, 11 VOCs were detected in at least one sample at or above 1.0 ??g/L; 6.6% of the water samples had a detection of at least one VOC at or above 1.0 ??g/L, and 2.6% had a detection of at least two VOCs at or above 1.0 ??g/L. Based on the statistical data of detection frequencies above the method detection limits, 75% of the samples detected at least one VOC, and 65% of the samples detected at least two VOCs. Chloroform, toluene, and 1,2-dichloroethene were the three most frequently detected VOCs, with detection frequencies of 76.97%, 68.42%, and 44.08%, respectively. Volatile halogenated hydrocarbons and gasoline components were the two most frequently detected VOC groups.     

环境空气中痕量挥发性有机硫监测分析方法研究

采用预浓缩系统与GC MS联用,建立了环境空气中痕量挥发性有机硫的分析方法,该法用苏玛罐或Tedlar袋采集空气样品在预浓缩系统中经液氮于-160℃冷冻浓缩后,进入GC MS进行分析。甲硫醇、乙硫醇、甲硫醚、乙硫醚、二甲二硫的最低检出限分别为2 0、1 0、1 0、1 0、0 5μg m3。经6次的重复测定,其相对标准偏差小于9 0%。该方法已用于环境空气的测定,取得了令人满意的结果。     

PM2.5 and volatile organic compounds (VOCs) in ambient air: a focus on the effect of meteorology

PM(2.5) and VOCs (benzene, toluene, m-p-o-xylenes) concentrations were measured in an urban and a suburban site in Athens, Greece, during the period between April and November 2004. This period, which is considered to be the warmer period in Greece, is characterized by the development of sea-breeze over the Attica Basin. Additionally strong Northern, North-eastern winds called "The Etesians", predominate during the summer months (July-August), acting positively to the dispersion of pollutants. In this campaign, 24 days with sea-breeze development were observed, 15 days with northern winds, 6 days with southern winds while the rest of the days presented no specific wind profile. Maximum concentrations of PM(2.5), VOCs and nitrogen oxides, were detected during the days with sea-breeze, while minimum concentrations during the days with northern winds. Ozone was the only pollutant that appeared to have higher concentrations in the background site and not in the city centre, where benzene presented strong negative correlation with ozone, indicating the photochemical reaction of hydrocarbons that lead to the ozone formation. The BTX ratios were similar for both sites and wind profiles, indicating common sources for those pollutants. T/B ratio ranged in low levels, between 3-5 for site A and 2-5 for site B, suggesting vehicles emissions as the main sources of volatile compounds. Finally, the strong correlations of PM(2.5) and benzene concentrations, between the two sampling sites, indicate that both the city centre and the background site, are affected by the same sources, under common meteorological conditions (sea-breeze, northern winds).     

杭州市居室空气中芳香族化合物污染现状及其来源解析

用热解吸/气质联用技术研究了杭州市居室空气中芳香族化合物的组成。结果表明,杭州市居室空气中共存在60种芳香族化合物,其中苯系化合物48种,非苯芳香族化合物12种,检出率大于50%的23种;苯、甲苯、乙苯、苯乙烯、邻二甲苯、间(对)-二甲苯等10种化合物的总含量之和大于85.39%,是室内空气中主要的芳香族污染物,除萘外,其他22种污染物的平均浓度值均随装修时间间隔延长而降低;污染物主要来源是室内装修过程中使用的或装修材料中残留的有机溶剂、机动车辆排放的尾气、居民家庭中常用的清洁用品及含萘等成分的防蛀剂。