Analytical oxidation of reserpine.

Electrochemical (anodic) oxidation of reserpine in an acidic medium results in the formation of 3,4-dehydroreserpine instead of the reported 10-hydroxy-reserpine. Electrochemical and chemical oxidation by sodium nitrite lead quantitatively to the same product; few by-products or consecutive products are formed if protected from light. The validity of the conditions of the spectrophotometric assay of the European Pharmacopoeia were confirmed by following the reaction using HPLC with a photodiode-array detector.