Linear Scanning Valtammetric Determination of Tanshinone ⅡA

The electrochemical behavior of Tanshinone ⅡA at hanging mercury electrode was studied by linear scanning voltammetry and cyclic voltammetry. In a 0.2 mol·L-1 HOAc-NaOAc buffer solution of pH 3.8, a sensitive reduction peak given by Tanshinone ⅡA was observed at -0.228 V (vs.Ag/AgCl). Linear relationship between values of peak current obtained by linear scanning voltammetry and concentration of Tanshinone ⅡA was kept in the range of 5.0×10-6-2.0×10-5mol·L-1, with detection limit (3S/N) of 2.7×10-7mol·L-1. The proposed method has been used in the determination of content of Tanshinone ⅡA in crude drugs of Salvia miltiorrhiza, and values of recovery found were in the range of 98.5%-100.1%. As shown by the results obtained by cyclic valtammetric scanning, the reduction of Tanshinone ⅡA at the electrode is a reversible process, controlled mainly by adsorption.