Electrochemical and electrophoretic study of sodium metamizole

Electrochemical and electrophoretic behavior of sodium metamizole under conditions of variable pH has been studied. Voltammetric results indicate that sodium metamizole behaves as a quasi-reversible system over the potential window considered. These studies were complemented with capillary zone electrophoresis analysis in order to know the starting composition of solutions of sodium metamizole at different pH values and buffer composition. Among degradation products, the extent of the active metabolite 4-methylaminoantipyrine was found to be media dependent as well as was the appearance of different degradation products. Consequently, the extent of the oxidation process in voltammetric studies is dependent on the composition of the starting solutions. Information obtained by cyclic voltammetry and capillary zone electrophoresis has been concordant and conclusive in that both methods can be used in a qualitative study of sodium metamizole, under the experimental conditions assayed.