毛细管气相色谱/石墨炉原子吸收联用测定土壤样品中的甲基汞

Determination on Methyl Mercury in Soil Samples by the Combination of Capillary GC-GFAAS

[目的]建立毛细管气相色谱（GC）-石墨炉原子吸收（GFAAS）联用测定甲基汞的方法。[方法]用正已烷萃取土壤样品中氯化甲基汞（MMC），以OV-17毛细管柱分离，于500℃检测氯化甲基汞的含量。[结果]用温度传感器测定管内温度并以自制电路系统将转移线温度控制在（120．0±0．5）℃。正已烷的背景吸收小，萃取效果较好，且沸点较低，毒性较小。价格便宜，故选用正已烷作萃取剂。加入EDTA消除了金属离子的干扰。原子化温度为500℃。标准工作曲线的方程为y=0．0109＋0．0024x。线性范围为8～50ng，相关系数为0．9972。MMC的检测限为0．6ng。污水处理池的淤泥中MMC的平均含量为28．7ng／g，其RSD与加标回收率分别为3．38％和90．8％。未从农田土壤样品中检测出MMC。[结论]该方法简便、快速、准确，可用于土壤样品中有机汞的分离测定。

[ Objective ] The purpose of the study was to establish the method of determining methyl mercury by the combination of capillary GC-GFAAS. [ Method] The methyl mercury chloride （MMC） was extracted from soil samples with n-hexane, isolated with OV-17 capillary column and its content was determined at 500 ℃. [ Result] The temperature in pipe was determined with temperature sensor and the tempera- ture of line of hitch of transference was controlled at （120.0±0.5）℃ with self-made circuit system. The background absorbance of n-hexane was little, its extraction effect was better, its boiling point was lower, its toxicity was less and it was cheap. So, it was selected as extractant. The disturbance of metal ions was eliminated through adding EDTA. The atomization temperature was 500℃. The equation of standard work- ing curve was y = 0. 010 9 ＋ 0. 002 4x, its linear range was 8 - 50 ng and its correlation coefficient was 0.997 2. The determination limit of MMC was 0.6 ng. The average content of MMC in the sludge from sewage treatment pool was 28.7 ng/g and its RSD and recovery of standard addition were 3.38% and 90.8% resp. There was no MMC determined from soil samples of farmland. [ Conclusion] This method was conven- ient, rapid and accurate and it could be used to isolate and determine organic mercury in soil samples.