DETERMINATION OF TIN(II) IN PHARMACEUTICALS BY AMPEROMETRIC OXIDATIONAFTER COMPLEXATION WITH TROPOLONE

Inorganic tin(II) was determined, rapidly and selectively in the prese nce of tin(IV), by electrooxidation after complexation with tropolone (2-hydroxy-2,4,6-cycloheptatrienone), By cyclic voltammetry, the tin(I I)-tropolone complex showed a well-defined irreversible oxidation peak which occurred at -0.014 V (vs. Ag/AgCl) at the glassy carbon electro de in 0.05 molL(-1) acetate buffer pH 5.5. The determination of Sn-II has been realized using FIA and by poising the electrode at +0.1 V. A linear relationship was obtained between peak current and tin(II) in t he concentration range 0.25-20 mu molL(-1). The detection limit was 0. 1 mu molL(-1) and the RSD calculated by injection of a 5 mu molL(-1) t in(II) solution was 1.5% (n = 10). The optimization of several experim ental parameters has been realized and the influence of many cations a nd possible interfering species encountered in radiopharmaceuticals an d in dental gels has been investigated. The method was applied to the determination of tin(II) in dental gels.