涂布2,4-二硝基苯肼的环形溶蚀器/滤膜系统和高效液相色谱法检测大气中二羰基化合物

建立了环形溶蚀器/滤膜系统(Annular denuder/filter pack system)和2,4-二硝基苯肼(DNPH)-高效液相色谱法(HPLC)采集和检测大气中气相和颗粒相二羰基化合物的方法。DNPH作为吸附剂分别涂布在环形溶蚀器的内壁和3层滤膜上,当大气样品经过环形溶蚀器时,含有气相二羰基化合物的气体吸附到环形溶蚀管内壁上与DN-PH发生反应,而颗粒相部分穿过环形溶蚀管,采集到滤膜上。样品经乙腈洗脱、浓缩后,采用HPLC进行分析。根据不同的采样流速、采样时间和DNPH的涂布量采集到的二羰基化合物的浓度,确定的最佳采样条件为:采样流速4 L/min,采样时间4~5 h,DNPH浓度0.47 g/L。使用Tedlar bag验证环形溶蚀器乙二醛和甲基乙二醛的采集效率(分别为82%和85%)。利用此方法对实际大气中的二羰基化合物进行了检测。

Determination of Airborne Dicarbonyls by HPLC Analysis Using Annular Denuder/Filter System Coated with 2,4-Dinitrophenylhydrazine

A HPLC method was developed using an annular denuder/filter pack sampling system coated with 2,4-dinitrophenylhydrazine (DNPH) for collecting gas- and particle-phase dicarbonyl compounds in the atmosphere. DNPH was used as a derivatizing agent to coat the denuders and the filters, when air flowed through the sampling system, the gases were absorbed and reacted with DNPH on the denuders while particles proceeded along the denuders and then analyzed by HPLC. The samples were extracted, concentrated and subjected to HPLC analysis. The sampling conditions of the system were investigated by a series of sampling experiments. The results indicated that when the coating DNPH solution was 0.47 g L⁻¹, the optimum collection efficiency was obtained at a flow rate of 4 L min⁻¹ for a sampling duration of 4–5 h. The collection efficiencies of glyoxal and methylglyoxal were 82% and 85%, respectively, which were determined using Tedlar bags. The method was applied to measure dicarbonyl compounds in the atmosphere.