Voltammetric behavior and determination of tanshinone II A at carbon paste electrode

The voltammetric behavior of tanshinone II A (TS) on carbon paste electrode (CPE) was studied. In 0.2 mol/L BR buffer (pH 2.4) -ethanol/water (40: 60, V/V) medium, the carbonyl group of TS under went a one-electron and one-proton redox reaction at CPE, which was a reversible process with adsorption character. The semiquinone radical of TS as reduction product existed stably on CPE, which might be that hydrophobic organic phase inhibited the disproportionation reaction of the radical of TS. The peak potentials of the reduction and oxidation were - 0.31 V and - 0.24 V (vs. SCE), respectively. The second-order derivative oxidation peak current showed a linear relationship with the concentration of TS in the range of 1.2 x 10(-8) similar to 21 x 10(-7) mol/L, and the detection limit was 4.1 x 10(-9) mol/L. The voltammetric method proposed can be used to determine the total tanshinone in compound Danshen tablet.