空气中BTEX检测方法研究进展

A Review of Determination of Benzene,Toluene,Ethylbenzene and Xylene in Ambient Air

BTEX (苯系物)作为空气中的一种痕量组分,主要包括苯、甲苯、乙苯、间-二甲苯、对-二甲苯、邻二甲苯,这些物质可影响人体健康和环境空气质量.分析和探讨了环境空气中BTEX常用的采样、前处理和检测方法,并列举了各方法的国内外应用实例. BTEX采样方法主要包括以下2种:①吸附管采样法,其采样器体积小、便于携带,但易造成穿透现象,样品易损失.②空气采样法,其操作简单、重复使用率高,但清洗复杂、价格较高. BTEX前处理方法主要包括以下3种:①固相微萃取法,其可减少样品与空气接触的机会,自动化程度较高,但难以实现样品的多次分析.②溶剂解析法,因其对环境影响较大,所以应用较少.③热脱附法,其常采用二级热脱附实现样品富集和浓缩,操作过程简单,设备体积相对较大,其升温和降温系统是影响前处理速度和效果的关键. BTEX检测方法主要包括:①质子转移反应质谱法,其灵敏度高,但因其价格昂贵应用较少.②气相色谱-光离子化检测法,其设备体积小巧常用于外场监测中.③差分吸收光谱法、直接空气进样质谱法、低压化学电离质谱法、大气压化学电离质谱法、固相微萃取-气相色谱法、吸附/热脱附-气相色谱-火焰离子检测法/质谱检测法等.研究显示,空气中BTEX的分析方法应根据实际应用条件来确定,在保证分析仪器灵敏度和精确度的基础上,开发外场检测的便携式自动在线分析仪器,提高仪器便携性、自动化、智能化,更好地满足各项标准和部门管理的需求.

Benzene,toluene,ethylbenzene and xylene( BTEX) are trace components in ambient air that affect human health and air quality. This review analyzes and discusses the sample collection methods,pretreatment methods,and analysis of BETX in ambient air.Applications of the various methods are exemplified. The main sampling methods include:( 1) The adsorption tube sampler is small to carry,but may be easily damaged,leading to a loss of sample when exposed to air.( 2) Whole-air sampling is simple and the sample can be reused. It is widely used in external field measurements,but cleaning of the equipment is complicated and expensive. The main pretreatment methods include:( 1) Solid-phase micro extraction can reduce contamination of the sample. It has a high degree of automation,but it is difficult to analyze samples repeatedly.( 2) Solvent analysis has an environmental impact. Therefore,this method is no longer employed.( 3) In thermal desorption,samples are usually enriched and concentrated using two-step thermal desorption. The operation is simple,but the equipment is large. The heating and cooling system is the key factor influencing the pretreatment time. The main analysis methods include:( 1) Proton-transfer-reaction mass spectrometry is not widely used because of its high price,but it has a high sensitivity.( 2) Gas chromatography with a photoionization detector is usually used in field measurements.( 3) Several other common analytical methods for BTEX analysis in ambient air are described,including differential optical absorption spectroscopy,direct air sampling-mass spectrometry,low-pressure chemical ionization,or atmospheric pressure chemical ionization,and gas chromatography with solid-phase micro extraction or adsorption/thermal desorption accessories. In order to meet the requirements of various standards and departmental management that the portable automatic online analytical instruments for field measurements are developed to improve the portability,automation and intelligence on the basis of sensitivity and accuracy of analytical instruments.