土壤中总铬测定方法的比较研究

采用国标GB/T 17137-1997和GB/T 17141-1997中规定的两种方法即H2SO4-HNO3-HF、HNO3-HF-HClO4法对土壤样品进行消解处理，筛选了HNO3-HF-HClO4消化体系并进行改进，再运用火焰原子吸收分光光度法测定样品中总铬（Cr）的含量。结果表明：土壤总Cr测定中的3种预处理方法的测定结果存在明显差异，改进后的HNO3-HF-HClO4法优于原国标方法，该方法消解速度快（3 ~ 4 h）且完全，大大缩短了实验时间；该方法灵敏度高（最低检出限0.04 mg/L）、准确度高（相对误差在1.3% ~ 5.0%）、加标回收率高（94.6% ~ 108.7%），精密度好（相对标准偏差小于5.7%），是值得推广的土壤Cr消解方法，可应用于农业环境土壤质量样品的检测。

Comparing study on method to determine total chromium in soil

In this paper, two kinds of methods, i.e., H2SO4-HNO3-HF and HNO3-HF-HClO4, regulated in the National Standard GB/T17137-1997 and GB/T17141-1997, were used to digest soil samples, and then HNO3-HF-HClO4 was selected and improved to determine the total concentration of chromium by using flame atomic absorption spectrometry. The results showed obvious differences in the measured results between the three kinds of pretreatment methods, among of which, the improved HNO3-HF-HClO4 method was best, it digests fast (3 - 4 h) and fully, reduces the test time greatly; it is of high sensitivity (the lowest detection limit was 0.04 mg/L), high accuracy (the relative error was 1.3% - 5.0% ), high the recovery of standard addition (94.6% - 108.7%) and good precision (the relative standard deviation was less than 5.7%), thus it is worth being applied to the detection of agricultural environmental samples of soil quality.