EDTA差减滴定法测定汞污染土壤中汞

提出了快速测定汞污染土壤中汞含量的EDTA差减滴定法。土壤样品用H3PO4和H2SO4混合酸溶解,用焦磷酸钠掩蔽Cu2+,调至pH5～6,以二甲酚橙为指示剂,用EDTA标准溶液滴定溶液中能与EDTA络合的全部金属离子的总量;然后在另一份相同试液中,先加入硫脲掩蔽Hg2+,再用EDTA标准溶液滴定除汞外的其它金属离子,利用二者之差计算汞的含量。改进后的方法,简单、快捷、干扰小,测定结果与国家标准方法一致,相对标准偏差小于2.0%,加标回收率在97.2%～100.1%之间。

Determination of mercury in mercury polluted soil by EDTA difference titration

A new method for the rapid determination of mercury content in mercury polluted soil by EDTA difference titration was established.After the soil sample was dissolved in H3PO4 and H2SO4,Na4P2O7 was used to mask Cu2 at pH 5-6.The total metal ions was titrated with the standard EDTA solution using XO as the indicator.While thiourea was added to another soil sample to mask Hg2 ,the ions except Hg2 in the solution was titrated by standard EDTA solution.The amount of mercury is calculated through the volume difference of EDTA solution expended in titration of two solutions.The result showed the method is easy and fast and less interference.The results of this method accord with those obtained by national standard method with RSD of less than 2.0% and recovery of 97.2%-100.1%.