环形扩散管和滤膜联用采集和测定大气中气固相物质

SIMULTANEOUS COLLECTION AND MEASUREMENT OF GASES AND THEIR ASSOCIATED PARTICULATES USING A DIFFUSION DENUDER WITH A FILTER PACK

建立了环形扩散管(annular diffusion denuder)和滤膜连用的采样装器。采用涂渍1％碳酸钠甲醇水溶液和5％亚磷酸甲醇溶液的两段环形扩散管串联分别收集气态HNO_3,HCl,SO_2和NH_3、空气经扩散管后,继而抽入滤膜采样头,用Teflon滤膜采集颗粒物,Nylon滤膜收集由Teflon滤膜上颗粒物挥发产生的气态HNO_3和HCl。样品提取后,用离子色谱法测定SO_4^(2-),NO_3^-和Cl^-;采用流动注射荧光法测定NH_4^+。当采样流速为10L/min,采样24h,环形扩散管对气态硝酸、氯化氢和二氧化硫的检出限(3σ)为0.04—0.09μg/m^3,对氨的检出限为0.12μg/m^3。实验结果表明本法适用于大气和室内空气的采样和测定。

A sampling method employing an annular diffusion denuder with a filter pack was established for the simultaneous collection of NH3, HNO3, HC1, SO2 and their associated aerosols. The denuder apparatus consisted of two annular diffusion denu ders in series. The first denuder was coated with a solution of 1% Na2CO3 in 1:1 methanol/water for collecting gaseous HCl, HNO3 and SO2, and the second denuder with a solution of 5% H3PO3 in methanol for gaseous NH3. Air was drawn through the denuders and subsequently through a PTFE filter pack comprising a Teflon filter for collecting suspended particulates and a Nylon filter for the evaporated HNO3 and HC1 front the Teflon filter. The collected samples were analyzed by ion chro-matography for Cl-, NO3 and SO42-. At the flow rate of 10 L/min sampling for 24h, the detection limits of gaseous HC1, HNO3 and SO2 were in the range of 0.04-0.09 μg/m3, and that of NH3 was 0.12μg/m3. The compact set up offers the feasible approach for collecting ambient and indoor air without the need of expensive equipment.