热脱附-单体稳定同位素技术测定挥发性有机物

采用热脱附与稳定同位素质谱联用技术分析了城市不同源及大气环境中挥发性有机物排放的单体同位素特征。系统考察了样品进样量、进样方式和样品分离度对同位素分馏影响情况。使用填有Tenax TA的吸附管采集汽油车尾气、汽油挥发、柴油车尾气、柴油挥发、溶剂挥发和餐饮油烟等污染源,以及城市不同功能区的挥发性有机物(VOCs)样品,不同污染源中挥发性有机物的稳定碳同位素δ13C值不同,97#汽油车尾气的δ13 C值偏重,平均值为-25.84‰,富集13 C；餐饮油烟的δ13 C值偏轻,平均值为-30.26‰。油品挥发比燃烧后以尾气的形式排放的苯系物δ13 C值重。厦门市各功能区挥发性有机物的δ13 C平均范围在-27.03‰~-25.40‰,接近于汽油和柴油挥发及尾气中的δ13 C值,表明厦门市空气中挥发性有机物以机动车排放源为主。

Analysis of Volatile Organic Compounds by Specific Carbon Stable Isotope

Theδ13 C values of volatile organic compounds ( VOCs) in various emission sources and ambient air were analyzed by using thermal desorption coupled with gas chromatography and isotope ratio mass. The lowest sample concentration and peak shape quality needed for high precision and accurate analysis were investigated. Fuel evaporation ( gasoline and diesel) , vehicle exhaust, solvent evaporation, dining fumes and ambient air of different functional zones of Xiamen city were collected using Tenax TA tube, and the significant differences in δ13 C values of VOCs between these sources were observed. The δ13 C value of gasoline exhaust ( 97 # ) was heavier (-25 . 84‰) than that of dining fumes (-30 . 26‰) and theδ13 C values of fuel evaporation were heavier than that of vehicle exhaust after combustion. The average δ13 C value of atmospheric VOCs in Xiamen was at the level of -27 . 03‰ to -25 . 40‰, which was close to the δ13 C value of the evaporation and exhaust of gasoline and diesel, indicating that the VOCs in the atmosphere of Xiamen was highly influenced by transportation related sources.