便携式气相色谱-质谱法测定炼化场地环境空气中的挥发性有机物

Determination of Volatile Organic Compounds in Ambient Air ofthe Refinery Sites Using Portable Gas Chromatography-Mass Spectrometry

基于吸附管采样/热脱附便携式气相色谱-质谱技术(GC-MS),建立环境空气挥发性有机物(VOCs)分析方法,考察方法的线性关系、重复性、准确性等。结果表明,该方法可以得到54种VOCs定量分析结果,化合物种类包括C_(3)~C_(12)的正构烷烃、异构烷烃、烯烃、环烷烃及苯系物。结合气相色谱流出时间及质谱谱库比对,可以准确进行化合物识别并得到单体化合物含量,校准曲线相关系数≥0.99,重复测定相对标准偏差范围分布在0.4%~8.2%之间,准确度分布在71%~101%之间,丙烷、丙烯检出限均为10 nmol/mol,C_(4)~C_(12)挥发性有机物检出限为1~5 nmol/mol,样品采集及分析总时间可以控制在30 min以内,可满足炼油化工场地日常监测预警及突发状况排查的需求。对炼油厂代表性样品的测定结果表明,不同采样点位化合物组成及浓度存在明显差异,可为后期在炼油厂区进行环境空气VOCs多组分监测、构建源排放化学特征谱库等工作提供基础数据。

Based on portable gas chromatography-mass spectrometry(GC-MS)coupled with sorbent adsorption and thermal desorption,a method was developed for the analysis of ambient air volatile organic compounds(VOCs).Then the linearity,repeatability and accuracy of the method were investigated.The results show that the method is capable for the quantitative analysis of 54 VOCs,including C_(3)—C_(12)n-alkanes,iso-alkanes,olefins,cycloalkanes,and benzene series.The identification of individual compounds can be achieved by the gas chromatographic retention time and mass spectra comparison.Calibration curve correlation coefficients exceeded 0.99;the relative standard deviations(RSD)after repeated determination ranged from 0.4%to 8.2%,and the accuracy distribution fell within the range of 71%to 101%;the detection limits of propane and propylene were 10 nmol/mol,while the detection limits of C_(4)—C_(12)volatile organic compounds were 1 to 5 nmol/mol.The total time of sample collection and analysis can be controlled within 30 minutes.The established method fulfills the requirements for daily monitoring,early warning and emergency investigation in refining and chemical sites.The results obtained from representative samples collected at various refinery sites show significant variations in composition and concentration of compounds,indicating the capability of this method to establish a comprehensive database for monitoring VOCs in ambient air and establishing a chemical characteristic profile database for emission source in subsequent stages.