SIMULTANEOUS DETERMINATION OF MELATONIN-PYRIDOXINE COMBINATION IN TABLETS BY ZERO-CROSSING DERIVATIVE SPECTROPHOTOMETRY AND SPECTROFLUOROMETRY

Two methods have been developed for the analysis of melatonin (M) and pyridoxine hydrochloride (PK) in combination. The first method depends on first- and second-derivative ultraviolet spectrophotometry, with t he zero crossing technique of measurement. First-derivative amplitudes at 296 nm and second-derivative amplitudes at 294 and 322 nm are sele cted for the determination of M and PH, respectively. The second metho d is based on the native fluorescence of both M and PH, in methanol an d 0.1 M hydrochloric acid, respectively, after a preliminary solvent e xtraction procedure. The relative standard deviation of both methods w as less than 2.0%. The two methods have been successfully applied to t he determination of both drugs in laboratory-prepared mixtures and in tablets (C) 1998 Elsevier Science B.V.