水为载流-原子荧光光谱法同时测定土壤中痕量砷、汞

改变原子荧光光谱法以稀酸为载流的进样方式,以水为载流在新型双道原子荧光光谱仪上同时测定了土壤中的痕量砷(As)、汞(Hg)。方法采用王水水浴加热溶解样品,用50 g/L硫脲-抗坏血酸混合溶液预先将砷还原为+3价,保持10%(体积分数)以上盐酸浓度,不转移直接定容静置后测定。优化了仪器工作条件,详细考察了以水为载流测定的可行性,选择了同时测定As、Hg所需的硼氢化钾浓度和盐酸浓度。方法节省了酸试剂用量,操作快速,单个样品测定仅需20s左右。方法检出限As为0.005 mg/kg,Hg为0.0008 mg/kg,相对标准偏差(RSD%,n=7)在1.0%～7.4%,经土壤国家标准物质和实际样品验证,适合土壤中痕量As、Hg的同时快速测定。

Simultaneous determination of trace arsenic and mercury in soil by atomic fluorescence spectrometry with water as carrier

In this paper, the trace arsenic and mercury in soil were determined by a new dual channel atomic fluorescence spectrometer with water as carrier instead of acid as carrier. The samples were dissolved by heating in a aqua regia bath. The arsenic was pro-reduced to + 3 by 50 g / L thiourea ascorbic acid mixed solution and the concentration of hydrochloric acid was kept above 10% (volume fraction). The samples were determined directly after standing at constant volume without transfer. The working conditions of the instrument were optimized, the feasibility of using water as carrier was investigated in detail, and the concentration of potassium borohydride and hydrochloric acid for the simultaneous determination of arsenic and mercury were selected. The operation of the method is fast, the determination of a single sample only takes about 20 s, and the amount of acid reagent is saved. The detection limits of arsenic and mercury are 0.005 mg / kg and 0.0008 mg / kg respectively and the relative standard deviation (RSD%, n = 7) is between 1.0% and 7.4%. Results for national standard material and practical sample test are satisfactory. It is suitable for the simultaneous and rapid determination of trace arsenic and mercury in soil.