计时电位溶出法测定天麻中的痕量砷

Determination of Arsenic in Gastrodia by Chronopotentiometric Stripping Analysis

以镀金玻碳电极为工作电极,计时电位溶出法测定天麻中的痕量砷。选择富集电位为-0.45V,溶出低液为3.0 mol/L的硝酸,在+0.14V电位处获得一灵敏的砷(Ⅲ)的二次微分电位溶出峰,且该溶出峰的峰高与砷的质量浓度在2.0～12.0μg/L范围内呈线性关系,方法的检出限(3S/N)为0.96μg/L。方法用于测定天麻中痕量砷的回收率为97.6%～102.4%,RSD为2.7%～3.1%。

A method for the determination of arsenic in Gastrodia by chronopotentiometric stripping analysis was proposed with gold-plated glassy carbon electrode as working electrode.A sensitive ondary differential potentiometric stripping peak of As（Ⅲ） was obtained at the potential of ＋0.14V,when accumulation potential taken was-0.45V and 3.0 mol/L HNO3 was used as base solution.Linear relationship between values of the peak height and mass concentration of arsenic were kept in the range of 2.0~12.0 μg/L.Detection limit（3S/N） of the method was found as 0.96 μg/L.The proposed method was used in the analysis of sample of gastrodia,giving values of recovery in the range from 97.6% to 102.4%,with RSD in the range of 2.7%~3.1%.