Oscillographic Determination of Zinc in Drug with Alizarin Red S

Alizarin red S(ARS) causes a sharp incision in 0.1 mol/L KBr. In the presence of Zn 2+ , the incision depth of ARS decreased and a new incision of Zn-ARS coordination compound appeared. A second order differential simple oscillographic voltammetric method for determination of Zn 2+ was developed. The method is applied to the determination of zinc gluconate in tablet. The linear range of Zn 2+ was 2.0×10 -7 ～8.6×10 -6 mol/L,detection limit 1×10 -7 mol/L, and RSD for determinations of 4.2×10 -6 mol/L Zn 2+ ( n=7 ) was 2.4%.