大气气溶胶中溴、碘总量及其形态的提取和测定

Extraction and Determination of Total Bromine,Iodine and Species in Atmospheric Aerosol

比较了超声纯水提取不同时间和多种密封提取条件下大气气溶胶样品滤膜中溴、碘形态稳定性和提取率。结果表明:密封提取方法的提取率高于超声提取方法,但有可能破坏了某种未知的有机碘形态;在长时间纯水超声条件下,醋酸纤维(CF)空白滤膜加标回收中I-形态不稳定。因此,纯水超声提取5 min为最佳提取条件。对比醋酸纤维(CF)和玻璃纤维(GF)空白滤膜加标回收实验发现,各种提取条件下GF材质对样品中溴、碘形态稳定性的干扰比CF材质小。在优化大气气溶胶溴、碘形态提取方法的基础上,建立了HPLC-ICP-MS测定大气气溶胶中BrO3-、Br-、IO3-和I-的方法,并对合肥地区气溶胶样品中溴、碘总量及形态进行测定。合肥地区气溶胶中溴和碘总量浓度分别为883和231 pmol/m3。其中,Br-占总溴的69%,BrO3-未检出;70%的碘为未知形态,包括可溶性有机碘和不可溶性碘。

The species of bromine and iodine in aerosol samples were extracted using ultra-pure water-ultrasonic method with different time in-length and pressurizing decomposition with dilute ammonia,respectively.The efficiency of extraction and the stability of bromine and iodine species were compared under different extraction conditions.Results showed that（1） the efficiency of extraction using pressurizing decomposition,which might destroy some unknown form of organic iodine,was relatively higher than the one by ultrasonic method;（2） I^-was unstable in added standard cellular blank filter during ultrasonic assisted extraction for long time;（3） The optimum condition was ultra-pure water-ultrasonic assisted extraction for 5 min.Moreover,the suitability of glass microfiber filter（GF） and cellular filter（CF） during extraction for bromine and iodine species in aerosol was also compared,which indicated that GF is favorable for species analysis than CF under different kinds of extraction conditions.Based upon the extraction results,HPLC-ICP-MS approach was developed to analyze bromine and iodine species in atmospheric aerosol.The total iodine,bromine and species in the aerosol samples collected in Hefei were then determined accordingly.The levels of total bromine and iodine in Hefei aerosols were 883 and 231 pmol/m^3,respectively.Br^-was found to be dominant species with 68%,while BrO3^- was undetectable.70% of total iodine occurred as unidentified forms including soluble organic iodine and insoluble iodine.