以一定浓度的硝酸为提取剂,在超声波辅助作用下对标准土壤/沉积物中的汞进行提取,并用冷原子吸收光谱法进行了分析。通过正交实验,优化了提取条件:硝酸浓度为9.0mol/L,超声频率为15 kHz,超声时间为10 min。Hg在0.1~10μg/L范围内线性关系良好。在优化的工作条件下,方法的检出限为0.009μg/L。与传统的水浴消解法进行了比较,发现超声辅助硝酸提取法提取效率为98.2%,相对误差(RE,n=4)为1.8%,都优于传统的水浴消解法。方法用于标准土壤和沉积物样品中汞的分析,结果与认定值相符,回收率分别为103%和99%,相对标准偏差(RSD,n=5)分别为0.55%和0.40%。
Mercury in soil/sediment certified reference materials was determined by cold vapor atomic absorption spectrometry(CV-AAS) after ultrasonic-assisted nitric acid extraction.Based on the results of orthogonal experiments,the extraction conditions were optimized as follows: nitric acid concentration was 9.0 mol/L,ultrasonic frequency was 15 kHz and ultrasonic time was 10 minutes.The linearity was good for Hg in the range of 0.1-10 μg/L.Under the optimum conditions,the detection limit for Mn was 0.009 μg/L.Experiment results showed that the extraction efficiency and the relative error(RE,n= 4) of ultrasonic-assisted nitric acid extraction method were 98.2 % and 1.8 %,respectively,which were all better than those of traditional water-bath digestion methods.This method has been applied to the analysis of mercury in soil and sediment certified reference materials,and the determination results accord with the certified values with the recoveries of 103 % and 99 % and relative standard deviations(RSD,n= 5) of 0.55 % and 0.40 %,respectively.