大气中气相和颗粒相羰基化合物的AD-FP系统采集和GC-MS分析

建立了涂布固体吸附剂XAD-4 和衍生剂五氟苄基羟胺(pentafluorobenzyl hydroxylamine hydrochloride, PFBHA)的环形溶蚀器-滤膜(annular denuder-filter pack, AD-FP)系统, 联合气相色谱-质谱(gas chromatography-mass spectrometer, GC-MS) 同时采集和检测大气中气相和颗粒相羰基化合物的方法. PFBHA 涂布在环形溶蚀器内壁和滤膜上, 当大气样品经过环形溶蚀器时, 气相羰基化合物被吸附, 颗粒相则被采集到滤膜上, 样品用正己烷洗脱和氮吹浓缩后再进行GC-MS 分析. 研究结果表明: 当PFBHA 涂布量为15 μmol(气相)和0.8 μmol(颗粒相)、采样流速为5 L/min、采样时间5 h 时, 对单羰基和二羰基化合物的采集效率达到最佳, 为84%～95%; 上海市宝山区大气中羰基化合物浓度水平呈现出季节性变化(夏季＜冬季), 且颗粒相羰基化合物浓度与PM_2.5浓度呈正相关, 羰基化合物的气粒分配系数与温度呈负相关.

Determination of gas and particle phase carbonyl compounds by AD-FP system and GC-MS

A GC-MS method were developed using an O-( 2, 3, 4, 5, 6-pentafluorobenzyl) hydroxylamine hydrochloride (PFBHA) and XAD-4 coated annular denuder-filter pack (AD-FP) system for collecting gas and particle phase carbonyl compounds simultaneously. PFBHA was used as a derivatizing agent to coat the denuders and filters. When air flowed through the sampling system, the gaseous compounds were absorbed on the denuders while particles proceeded along the denuders and collected on the filters. The samples were extracted by n-hexane and concentrated, and then analyzed by GC-MS. The results suggest that the good collection efficiency can be achieved when the coating amount is 15 μmol (gas phase) and 0.8 μmol (particle phase) and the sampling flow rate is 5 L/min for 5 h. Collection efficiencies of carbonyl compounds were between 84% and 95%. The level of atmospheric concentration of carbonyl compounds showed seasonal variation (the concentrations of carbonyls in winter were higher than in summer) in Baoshan District, and the particle phase had a positive correlated with PM2.5. The gas-particle partitioning coefficient of carbonyl compounds was negatively correlated with temperature.