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。

Determination of 67 volatile organic compounds in ambient air using thermal desorption-gas chromatography-mass spectrometry

A method based on thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) was developed for the simultaneous analysis of 67 volatile organic compounds (VOCs) in ambient air. In this study, the adsorption effects of five kinds of stainless steel sorbent tubes for 78 VOCs were compared. The results revealed that a multisorbent bed with Carbograph 1TD and Tenax TA shows good adsorption effect for the 67 target compounds. The breakthrough rates of all the target compounds were less than 10% when high-purity helium gas was continuously purged for 45 min at 30 mL/min. The analytes included aromatic hydrocarbons, aliphatic hydrocarbons, halogenated hydrocarbons, and oxygen-containing volatile organic compounds. The thermal desorption conditions for the determination of the target substances were optimized. In the range 5-100 ng, the chromatographic response of the target compounds had a good linear relationship with their corresponding amounts, and the correlation coefficient (r) was between 1.0000 and 0.9977. The method detection limits (MDLs) were 0.3-2.4 ng or 0.3-2.4 μg/m³, as calculated by a 1 L sampling volume. The method was validated by means of recovery experiments (n=7) with the addition of 20 ng standard samples. The recoveries of all the target compounds were in the range of 81.6%-114.9%, and their relative standard deviations (RSDs) were in the range of 1.2%-10.2%. The VOCs present in the air in a carriage were detected using this method. The 19 target compounds included esters, halogenated alkanes, halogenated olefins, and aromatic substances, whose concentrations ranged from 1.1 to 84.1 μg/m³. These results indicated that our method is accurate, reliable, and sensitive, and can allow for accurate quantification of the 67 target pollutants in ambient air.