Water determination in drugs containing ascorbic acid

A new rapid analytical method was applied for water determination in tablet s of vitamin C, Ce De Calcium Veterinary, and C-Tamin500 containing ascorbi c acid and therefore is not amenable for direct Karl Fischer (KF) titration . The method is based on the consecutive titration first of ascorbic acid b y a novel reagent and then of water by a conventional KF reagent (KFR) in t he same sample and cell with the electrometric "dead-stop" location of the endpoint in both titrations. The new reagent consists of iodine, potassium iodide, and sodium acetate in nonaqueous medium. Estimated repeatability an d accuracy of both water and ascorbic acid determination are satisfactory.