氢化物发生-原子吸收分光光度法检测环境样品中砷

Determination of arsenic in environmental samples by hydride generation atomic absorption spectrometry

氢化物发生-原子吸收分光光度法因其分析成本适中、操作简单,已逐步用于环境样品中砷元素的检测。本文通过控制变量法设计实验方案,研究了氢化物-原子吸收分光光度法测定样品中砷含量的最优实验条件,试验结果表明检测样品中砷含量的最佳条件为:分析波长为193.7nm,灯电流为11m A,燃烧器高度为16mm,狭缝宽度为1.0nm,燃气乙炔流量为2.0L·min^(-1),测定溶液基体为体积分数10%盐酸溶液,载液盐酸浓度质量分数为15%,载液Na BH4浓度为8g·L^(-1)。通过对地表水样加标回收试验和土壤标准物质中砷含量测定来考察方法的准确度,对已知浓度砷标准溶液连续测定考察方法的精密度,以及对空白样进行连续测定确定方法的检出限,结果该法的检出限为0.26ng·m L^(-1),水样加标回收率在98.9%~103.3%之间,土壤标准物质中砷含量测定值达标,其相对标准偏差为3.37%,表明该法具有精密度好、准确度高,可以用来检测环境样品中的低含量砷。

Because of the hydride generation atomic absorption spectrophotometric method easily operation and the low cost, it has gradually been used in the detection of arsenic in environmental samples. This article finds out the optimal analysis conditions by designing controlling variables experiments. The experimental results prove that the best testing conditions are as follows： detection wavelength 620nm, lamp current 1 lmA, burner height 16 mm, slit width 1.0nm, gas flow 2.0L·min^-1, the acidity of sample 10% hydrochloric acid solution, the concentration of hydrochloric acid solution 15%, the concentration of NaBH4 solution 8g·L^-1. The detection limit of the method is 0.266ng·mL^-1. The recovery of water sample by additional standard method is the range of 98.9%-103.3%. The arsenic in soil reference materials （GSS-25） is 12.6mg·kg^-1 with the relative deviation of 3.37 % which is agreed with the standard values within definite uncertainty. This method can be applied to analysis the arsenic in soil and water samples with reliable results.