Polarographic behaviors of diclofenac sodium in the presence of dissolved oxygen and its analytical application.

The polarographic response characteristics of diclofenac sodium were investigated in 0.25 M HAc-NaAc (pH 5.0) supporting electrolyte in the absence and the presence of dissolved oxygen. The results demonstrate that the reduction peak at ca. -1.10 V is a catalytic hydrogen wave after deaeration, and the reduction peak in the presence of dissolved oxygen is a so-called parallel catalytic hydrogen wave. Based on the parallel catalytic hydrogen wave, a novel method has been proposed for the determination of diclofenac sodium by single-sweep polarography. The calibration curve is linear in the range 1.2 x 10(-7)-2.6 x 10(-6)M and the detection limit is 6.0 x 10(-8)M. The proposed method is applied to the direct determination of diclofenac sodium in tablet forms and biological samples.