Direct stability-indicating method development and validation for analysis of etidronate disodium using a mixed-mode column and charged aerosol detector

This paper describes the development and validation of a rapid, direct, and stability-indicating method for analysis of etidronate, a bisphosphonate compound without a UV chromophore. A mixed-mode column was used to separate etidronate from its impurities in an 8-min gradient method and a charged aerosol detector (CAD) was used for detection. The developed HPLC method was validated with respect to specificity, linearity, accuracy, precision, sensitivity, and stability. The method can be used for release and stability testing of etidronate and has applicability to other similar bisphosphonate compounds.