大气有机物GC分析预处理中的组分损失  

LOSS OF ORGANIC COMPOUNDS IN PRECONCENTRATION OF AIR SAMPLE

作　　者：何大森 李似姣[1] 赵雷洪[1] 王燕妩 

机构地区：[1]浙江师范大学化学系,浙江金华321004

出　　处：《环境化学》1996年第3期266-272,共7页Environmental Chemistry

基　　金：浙江省分析测试基金

摘　　要：大气有机物在脱水、富集过程中的组分损失造成GC分析的系统误差.回收率测定表明,在本实验条件下,疏水性有机组分在填充碱石棉与碳酸钾的脱水预柱上的损失率分别为25%和15%左右,亲水性的乙醇的损失率高达60%左右.关于泄漏体积的冲洗色谱法研究表明,只要适当控制脱水条件(干燥剂用量、温度、空气样品的流通量等),上述两种脱水材料可以脱除空气样品中的95%水份,并使C_7以内疏水性有机物的损失率小于5%.从FID的相对校正因子(fw)看,深冷浓缩过程中有机组分的损失可以忽略不计.若在低温浓缩前采用干冰温度(-30℃)下的特氟隆空心管脱除水分,由于部分有机组分损失而使fw偏高.但是FID校正因子是在脱水空心管前面进样标定的,其分析结果与另一套不需脱水处理的低温浓缩-GC分析系统一致.The recoveries measured in this study show that the losses of hydrophobic organic compounds (HBOC)on drying column fitted with alkaline,asbestos or K2CO3 were about 25% and 15% respectively, and hydrophilic ethyl alcohol up to about 60%. The breakthrough volumes evaluated by elution gas chromatography demonstrate the possibility that, under certain conditions (certain amount of dryer, temperature, flux of air sample etc. ), both alkaline asbestos and K2CO3 will remain more than 95% of moisture but less than 5% of HBOC from ambient air samples. The results of relative weight sensitivity factor (fw) for FID indicate that the losses of organic compounds in a cryogenic precon centration system using liquid argon ( -180℃ ) as cooler can be neglected. However, the values of fw for another system in which a FEP teflon tubing cooled with dry-ice to - 30℃ was used as the water trap and was placed before the preconcentration U-trap show that a quantity of organic compounds were trapped. The losses can be compensated if the calibration was conducted by injection of standards in the position before the water-trap tubing. The method for preparation of standards with low concentration were also discussed.

关 键 词：空气分析 样品富集 色谱标定 大气有机物 

分 类 号：X131[环境科学与工程—环境科学]