Voltammetric behavior of 4',7-dimethoxy-3'-isoflavone sulfonic sodium and its enhancement determination in the presence of surfactant.

Voltammetric behavior of 4',7-dimethoxy-3'-isoflavone sulfonic sodium (DISS) was studied by linear sweep voltammetry and cyclic voltammetry. DISS caused two waves between pH 8.0 and 12.0. Above pH 8.0, the peak current of first wave Pc1 of DISS was enhanced in the presence of cetyltrimethylammonium bromide (CTAB). Based on this, a novel method for the determination of DISS was proposed. In Britton-Robinson buffer solution (pH 11.7) containing 9.4 x 10(-6)mol L(-1) CTAB, the peak potential of first wave Pc1 of DISS was -1.59 V (vs standard saturated calomel electrode) and its first-order derivative peak current was proportional to the concentration of DISS in the range 5.0 x 10(-8)-6.0 x 10(-7)mol L(-1) (r=0.998). The detection limit was 1 x 10(-8)mol L(-1), which was 10 times lower than that of the corresponding reduction wave. The method was applied to the determination of DISS in synthetic samples.