The electrochemical behavior of sodium 4',7-dimethoxy-3'-isoflavone sulfonate (SDIS) in aqueous medium from pH 1.0 to 12.0 was investigated with linear sweep voltammetry and cyclic voltammetry. Experimental results showed that SDIS could cause two reductive waves in different range of pH. In pH 1.0～8.0, the carbonyl group C≡O in SDIS underwent a 1e^- and 1H⁺ reduction to form a neutral free radical, and then 1e^- and 1H⁺ reduction of the free radical happened, but the wave of reduction species radical of SDIS was covered because of a discharge of hydrogen ion into the electrolyte solution in pH=5.1 to 8.0. In 0.2 mol·L^-1 Britton-Robinson buffer solution of pH8.0, SDIS could cause two reduction waves. The former was an irreversible wave of promoted SDIS involving 1e^- and the latter was also an irreversible wave of reduction species radical of SDIS involving 1e^- and 1H^+.

Key words: electrochemical behavior, reduction, sodium 4’,7-dimethoxy-3’-isoflavone sulfonate