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.     

Background concentrations of individual and total volatile organic compounds in residential indoor air of Schleswig-Holstein, Germany

During a monitoring campaign concentrations of volatile organic compounds (VOCs) were measured in indoor air of 79 dwellings where occupants had not complained about health problems or unpleasant odour. Parameters monitored were the individual concentration of 68 VOCs and the total concentration of all VOCs inside the room. VOCs adsorbed by Tenax TA were then analysed by means of thermal desorption, gas chromatography and mass spectrometry. The analytical procedure and quantification was done according to the recommendation of the ECA-IAQ Working Group 13 which gave a definition of the total volatile organic compound (TVOC) concentration. Using this recommendation TVOC-concentrations ranged between 33 and 1600 microg m(-3) with a median of 289 microg m(-3). Compounds found in every sample and with the highest concentrations were 2-propanol, alpha-pinene and toluene. Save for a few samples, all concentrations measured have been a factor 2 to 10 lower, compared to data from similar studies. Only a few terpenes and aldehydes were found exceeding published reference data or odour threshold concentrations. However, it has been found that sampling and analysing methods do have a considerable impact on the results, making direct comparisons of studies somewhat questionable. 47% of all samples revealed concentrations exceeding the threshold value of 300 microg TVOC m(-3) set by the German Federal Environmental Agency as a target for indoor air quality. Using the TVOC concentration as defined in the ECA-IAQ methodology is instrumental in assessing exposure to VOCs and identifying sources of VOCs. The background concentrations determined in this study can be used to discuss and interpret target values for individual and total volatile organic compounds in indoor air.     

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。     

云南省宣威市和富源县空气和土壤中多环芳烃污染水平研究

宣威市和富源县位于我国云南省东北部,是全世界肺癌发病率最高的地区之一。当地居民在不通风的房间内燃烧烟煤做饭或取暖造成了严重的室内空气污染。研究表明,长期暴露在燃煤造成的污染物中是导致两地居民肺癌持续高发的主要原因,多环芳烃是最可疑的致病因子之一。2008年1月,分别用聚胺脂泡沫和玻璃纤维滤膜采集了当地9个点位室内、室外空气中气相和颗粒物相中的多环芳烃,同时采集了对应点位的土壤样品。通过对样品的分析,考察了当地空气和土壤中多环芳烃的污染水平、特征以及来源。结果证明,当地空气和土壤中存在严重的多环芳烃污染,室内污染显著高于室外,然而随着当地工业的发展室外污染同样不可忽视,主成分分析结合比值法证明,当地室内外多环芳烃的主要污染源来自于煤炭的燃烧。对空气颗粒物和土壤中多环芳烃浓度进行了比较,对土壤中多环芳烃的来源进行了验证。     

预冷浓缩系统与气相色谱——质谱法测定室内空气中挥发性有机物

针对室内空气挥发性有机物测定方法的不足,本文采用预冷浓缩系统和气相色谱,质谱联用。建立了测定室内空气中39种挥发性有机物的分析方法,该方法采用苏码罐采样,经液氮预冷冻浓缩后,用心城由检测。该方法灵敏度高,操作简便、重现性好、准确度高,适用于室内空气中挥发性有机物的测定。     

A positive chemical ionization GC/MS method for the determination of airborne ethylene glycol and propylene glycols in non-occupational environments

An analytical method for ethylene glycol and propylene glycols has been developed for measuring airborne levels of these chemicals in non-occupational environments such as residences and office buildings. The analytes were collected on charcoal tubes, solvent extracted, and analyzed by gas chromatography-mass spectrometry using a positive chemical ionization technique. The method had a method detection limit of 0.07 microg m(-3) for ethylene glycol and 0.03 microg m(-3) for 1,2- and 1,3-propylene glycols, respectively, based on a 1.44 m3 sampling volume. Indoor air samples of several residential homes and other indoor environments have been analyzed. The median concentrations of ethylene glycol and 1,2-propylene glycol in nine residential indoor air samples were 53 microg m(-3) and 13 microg m(-3) respectively with maximum values of 223 microg m(-3) and 25 microg m(-3) detected for ethylene glycol and 1,2-propylene glycol respectively. The concentrations of these two chemicals in one office and two laboratories were at low microg m(-3) levels. The maximum concentration of 1,3-propylene glycol detected in indoor air was 0.1 microg m(-3).     

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.     

Indoor/ambient residential air toxics results in rural western Montana

Indoor and ambient concentrations of 21 volatile organic compounds (including 14 hazardous air pollutants) were measured in the homes of nearly 80 western Montana (Missoula) high school students as part of the 'Air Toxics Under the Big Sky' program during the 2004/2005 and 2005/2006 school years. Target analytes were measured using low flow air sampling pumps and sorbent tubes, with analysis of the exposed samples by thermal desorption/gas chromatography/mass spectrometry (TD/GC/MS). The results reported here present the findings of the first indoor/ambient air toxics monitoring program conducted in a semi-rural valley location located in the Northern Rocky Mountain/Western Montana region. Of all of the air toxics quantified in this study, toluene was found to be the most abundant compound in both the indoor and ambient environments during each of the two school years. Indoor log-transformed mean concentrations were found to be higher when compared with ambient log-transformed mean concentrations at P < 0.001 for the majority of the compounds, supporting the results of previous studies conducted in urban areas. For the air toxics consistently measured throughout this program, concentrations were approximately six times higher inside the student's homes compared to those simultaneously measured directly outside their homes. For the majority of the compounds, there were no significant correlations between indoor and ambient concentrations.     

硫氰酸汞分光光度法测定空气中氯化氢空白值偏高原因分析

通过实验,证明了硫氰酸汞分光光度法测定空气中氯化氢空白值偏高的主要原因,是由于两种显色剂之间相互反应引起的。因此,在测定过程中,显色剂的加入量必须十分准确。     

Application of CFD Methods for Modelling in Air Pollution Problems: Possibilities and Gaps

Different urban air pollution problems deal with complex structure of air flows and turbulence. For such problems the Computer Fluid Dynamics (CFD) methods become widely used. However, this approach despite a number of advantages has some problems. Experience of use of CFD tools for development of models and suggestions of their applications for a local scale air pollution over a complex terrain and stable stratification are discussed in this paper, including: Topography and complex geometry: choose of the co-ordinate system and computer grid; Turbulence closure for air pollution modelling: modified k- model for stable stratified ABL; Boundary conditions for vertical profiles of velocity for stable-stratified atmosphere; Effects of the radiation and thermal budget of inclined surfaces to dispersion of pollutants; Artificial sources of air dynamics and circulation.Some examples of CFD applications for air pollution modelling for a flat terrain, mountainous area, mining open cast and indoor ventilation are discussed. Modified k- model for stably-stratified ABL is suggested. Due to the isotropic character of the k- model a combination of it in vertical with the sub-grid turbulence closure in horizontal can be more suitable for ABL. An effective scheme of boundary conditions for velocity profiles, based on the developed similarity theory for stable-stratified ABL, is suggested. Alongside with the common studies of atmospheric dispersion, the CFD methods have also demonstrated a good potential for studying anthropogenic and artificial-ventilation sources of air dynamic and circulation in local-scale processes of air pollution.     

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。     

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.     

A novel in vitro exposure technique for toxicity testing of selected volatile organic compounds

Exposure to vapours of volatile chemicals is a major occupational and environmental health concern. Toxicity testing of volatile organic compounds (VOCs) has always faced significant technological problems due to their high volatility and/or low solubility. The aim of this study was to develop a practical and reproducible in vitro exposure technique for toxicity testing of VOCs. Standard test atmospheres of xylene and toluene were generated in glass chambers using a static method. Human cells including: A549-lung derived cell lines, HepG2-liver derived cell lines and skin fibroblasts, were grown in porous membranes and exposed to various airborne concentrations of selected VOCs directly at the air/liquid interface for 1 h at 37 degrees C. Cytotoxicity of test chemicals was investigated using the MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) and NRU (neutral red uptake) assays following 24 h incubation. Airborne IC(50) (50% inhibitory concentration) values were determined using dose response curves for xylene (IC(50)=5350+/- 328 ppm, NRU; IC(50)=5750+/- 433 ppm, MTS in skin fibroblast) and toluene (IC(50)=0 500+/- 527 ppm, NRU; IC(50)=11,200 +/- 1,044 ppm, MTS in skin fibroblast). Our findings suggest that static direct exposure at the air/liquid interface is a practical and reproducible technique for toxicity testing of VOCs. Further, this technique can be used for inhalational and dermal toxicity studies of volatile chemicals in vitro as the exposure pattern in vivo is closely simulated by this method.     

Indoor air quality during renovation actions: a case study

A temporary renovation activity releases considerably high concentrations of particulate matter, viable and non-viable, into air. These pollutants are a potential contributor to unacceptable indoor air quality (IAQ). Particulate matter and its constituents lead, sulfate, nitrate, chloride, ammonium and fungi as well as fungal spores in air were evaluated in a building during renovation action. Suspended dust was recorded at a mean value of 6.1 mg m(-3) which exceeded the Egyptian limit values for indoor air (0.15 mg m(-3)) and occupational environments (5 mg m(-3)). The highest particle frequency (23%) of aerodynamic diameter (dae) was 1.7 microm. Particulate sulfate (SO(4)(2-)), nitrate (NO(3)(-)), chloride (Cl(-)), ammonium (NH(4)(+)) and lead components of suspended dust averaged 2960, 28, 1350, 100 and 13.3 microg m(-3), respectively. Viable fungi associated with suspended dust and that in air averaged 1.11 x 10(6) colony forming unit per gram (cfu g(-1)) and 92 colony forming unit per plate per hour (cfu p(-1) h(-1)), respectively. Cladosporium(33%), Aspergillus(25.6%), Alternaria(11.2%) and Penicillium(6.6%) were the most frequent fungal genera in air, whereas Aspergillus(56.8%), Penicillium(10.3%) and Eurotium(10.3%) were the most common fungal genera associated with suspended dust. The detection of Aureobasidium, Epicoccum, Exophiala, Paecilomyces, Scopulariopsis, Ulocladium and Trichoderma is an indication of moisture-damaged building materials. Alternaria, Aureobasidium, Cladosporium, Scopulariopsis and Nigrospora have dae > 5 microm whereas Aspergillus, Penicillium and Verticillium have dae < 5 microm which are suited to penetrate deeply into lungs. Particulate matter from the working area infiltrates the occupied zones if precautionary measures are inadequate. This may cause deterioration of IAQ, discomfort and acute health problems. Renovation should be carefully designed and managed, in order to minimize degradation of the indoor and outdoor air quality.     

Determination of ortho-phthalaldehyde in air and on surfaces

Three sampling and analytical methods have been developed and evaluated for ortho-phthalaldehyde (OPA): (1) an HPLC-UV method for OPA in air, (2) a fluorimetric method for OPA on surfaces, and (3) a colorimetric method for OPA on surfaces. (1) The air sampler contains 350 mg of silica gel coated with 1 mg of acidified 2,4-dinitrophenylhydrazine (DNPH). Air sampling may be conducted at 0.03 to 1.0 L min(-1) for periods up to 8 h. Samples were eluted with ethyl acetate, and the eluents were allowed to stand for 72 h. Analysis was by high performance liquid chromatography (HPLC) with a UV detector set at 369 nm. An unusual phenomenon was the observation that the stability of the sample on a sampler at 3 degrees C tends to decrease as the total quantity of OPA collected on the sampler decreases. Elution of the samples within 24 h of air sampling is required. The detection limit (LOD) is approximately 0.02 microg of OPA per sample. OPA on surfaces may be collected with strips cut from a sheet of polyvinyl alcohol (PVA wipe). (2) In the surface wipe method with analysis by fluorescence measurement, the strips of PVA wipe were placed into dimethyl sulfoxide. An aliquot was treated with aqueous N-acetyl-l-cysteine and ethylenediamine. Analysis was performed with a portable fluorometer (excitation and emission wavelengths = 365 nm and 438 nm, respectively). The LOD is 0.2 microg per sample. (3) In the surface wipe method with visual colorimetric detection, the strips of PVA wipe were placed into 30 : 70 acetonitrile : water. An aliquot was treated with N-(1-naphthyl)ethylenediamine in 0.1 m sulfuric acid. After color development, the LOD is approximately 48 microg per sample. These methods have been field tested in a hospital.     

Indoor air pollution by 2-ethyl-1-hexanol in non-domestic buildings in Nagoya, Japan

2-Ethyl-1-hexanol is a possibly causative chemical in sick building symptoms, although 2-ethyl-1-hexanol has received little attention as a hazardous substance in studies on indoor air pollution. Airborne 2-ethyl-1-hexanol concentrations were measured from 2002 to 2004 in 99 rooms of 42 non-domestic buildings in Nagoya, Japan. The diffusive sampling method is effective for the measurement of a low level of 2-ethyl-1-hexanol in indoor air. The geometric mean (geometric standard deviation) of 2-ethyl-1-hexanol concentrations was 16.5 (5.4) microg m(-3) in indoor air and 1.9 (2.2) microg m(-3) in outdoor air. The maximum concentration of 2-ethyl-1-hexanol in indoor air and outdoor air was 2709 microg m(-3) and 12.4 microg m(-3), respectively. Fewer rooms in a small number of new buildings showed high concentrations of 2-ethyl-1-hexanol, while low concentrations were observed in many rooms of these buildings as well as the other new buildings. The room-to-room concentrations of 2-ethyl-1-hexanol in each building exhibited a wide variation. The geometric mean of the 2-ethyl-1-hexanol concentrations was significantly higher for indoor air than for outdoor air (p < 0.01). The correlation of the 2-ethyl-1-hexanol concentrations between indoor and outdoor air was not significant. Mechanical ventilation was effective in the temporary reduction of indoor 2-ethyl-1-hexanol level. These results suggest that the predominant source of 2-ethyl-1-hexanol was indoor areas.     

Organophosphate triesters in indoor environments

In this study the occurrence of ten organophosphate triesters in indoor air at 29 different locations was investigated. They were detected at all locations and a total of ten compounds were identified. The predominant compounds were the chlorinated compounds tris(chloroisopropyl) phosphate and tris(2-chloroethyl) phosphate with a concentration around 2 microg m(-3) in some indoor environments. A rough estimation gives at hand a daily inhalation of around 10 microg for each of these two compounds.     

Indoor air in schools and lung function of Austrian school children

The Children's Environment and Health Action Plan for Europe (CEHAPE) of WHO focuses (inter alia) on improving indoor environments where children spend most of their time. At present, only little is known about air pollution in schools and its effect on the lung function of school children. Our project was set up as an Austrian contribution to CEHAPE. In a cross-sectional approach, differences in indoor pollution in nine elementary all-day schools were assessed and 34 of these pollutants were analyzed for a relationship with respiratory health determined by spirometry using a linear regression model. Overall 596 children (aged 6-10 years) were eligible for the study. Spirometry was performed in 433 children. Socio-economic status, area of living (urban/rural), and smoking at home were included in the model as potential confounders with school-related average concentration of air pollutants as the variable of primary interest. A negative association with flow volumes (MEF(75)) was found for formaldehyde in air samples, benzylbutylphthalate and the sum of polybrominated diphenylethers in school dust. FVC and FEV(1) were negatively associated with ethylbenzene and xylenes in air samples and tris(1,3-dichlor-2-propyl)-phosphate on particulates. Although, in general, the quality of school indoor air was not worse than that reported for homes, effects on the respiratory health of children cannot be excluded. A multi-faceted strategy to improve the school environment is needed.     

室内空气有机污染的研究现状

主要讨论了室内空气中有机物污染的研究现状。重点介绍了室内空气中多环芳烃 (PAHs)、挥发性有机物(VOCs)、醛类化合物等的污染状况及来源。简要叙述了室内空气污染的影响因素及对人体的健康风险评价。     

Recommendations for Monitoring of Polybrominated Diphenyl Ethers in the Canadian Environment

Polybrominated diphenyl ethers (PBDEs) have been reported in air, surface waters, suspended sediments, soil, sediment, fish, marine mammals, and bird eggs throughout Canada, from the St. Lawrence Estuary to the Strait of Georgia and the northernmost reaches of the Canadian Arctic. Canadian scientists have detected the presence of PBDEs in breast milk in every Canadian province. In fact, recent data on temporal trends strongly suggests that the concentrations of PBDEs are on the rise in the Canadian environment. These findings are similar to those reported in other nordic countries, and have prompted several countries to implement environmental monitoring programs. Among the key challenges currently facing Canada and other countries concerns how best to measure these chemicals in different matrices. In this paper, several analytical methods cited in the scientific literature for determining PBDE concentrations in different abiotic and biological matrices are reviewed. The critical criteria required for accurate determination of PBDEs in complex environmental matrices are discussed, including instrument sensitivity, reliability, potential interference's and the need for specialized instrumentation for the determination of compounds up to 975 Daltons. While a single analytical method that meets these and other criteria has not yet been perfected by scientists, GC/HRMS-based methods amenable to isotope dilution techniques warrant further refinement, and likely represent the best tools for future environmental monitoring programs.