Electrochemical reduction and quantification of menadione in sodium dodecyl sulfate micellar media

Menadione cyclic voltammograms show a pair of redox steps on glassy carbon electrode in 0.1 M H3PO4 with potential separation of 343 mV. Cationic, nonionic, and anionic surfactants micellar media significantly decrease the menadione peak potential separation. Statistically significant increase of menadione reduction current (3- and 4.4-fold) has been observed in Triton X 100 and sodium dodecyl sulfate (SDS) micellar media, respectively. Electrochemical reduction of menadione in 9 mM SDS micellar media is reversible diffusion-controlled one-electron process corresponding to formation of relatively stable semiquinone anion radical. The linear dynamic ranges of menadione determination are 7-560 and 600-2,550 mu M with the limits of detection and quantification of 1.66 and 5.53 mu M, respectively. The current concentration sensitivity is (8.6 +/- 0.2) x 10(3) mu A mu M-1. The voltammetric method for the determination of menadione in pharmaceutical Aekol based on preliminary extraction with ethanol has been developed.