Capillary electrophoresis method for determination of related substances in glutathione reduced drug substance

Summary A sensitive capillary electrophoretic method using low pH with direct UV detection has been developed to evaluate the impurity profile of reduced glutathione obtained from its production and purification. The method is characterized by high detection sensitivity and selectivity. Validation has been performed with model mixtures consisting of the main known related substances—oxidized glutathione, glutamylcystein, cysteinylglycine and cysteine. The results from this study show that with respect to quantification criteria the method is acceptable for routine control of reduced glutathione for pharmaceutical application.