SPECTROPHOTOMETRIC DETERMINATION OF ZINC IN MULTIVITAMIN PHARMACEUTICAL PREPARATIONS WITH THE USE OF AZO DYES SERIES 1,2,4-TRIAZOLE (METRIAN, METRIAREZ-GAMMA) AND BENZIMIDAZOLE (BIAR)

2-(2',4'-Dihydroxyphenylazo-1')-benzimidazole (Biar, (1)); ercapto-5-( 2'-hydroxynaphtylazo-1')-1,2,4-triazole (Metrian, (2)) and '-dihydroxy -3'-carboxyphenylazo-1')-1,2,4-triazole (Metriarez-gamma, (3)) were pr oposed to the spectrophotometric determination of Zn ions in multivita mine pharmaceutical preparations. Zn2+ ions in the methanol-aqueous me dium at pH 7.20 (3) and Ph 9.23 (1,2) form stabile red complexes with a molar ration L:ZN = 2:1 and log K values - 11.471 (3), 10.700 (1) an d 10.311 (2). The other components of the examined preparations (Ca, M g, Na, K, Mn, Mo, Se, Co, Cu, Fe, P) do not interfere with Zn2+ ions d etermination or they were eliminated at reaction conditions. Determina tion results were elaborated statistically and compared with results o btained using AAS method. The advantage of described method is its goo d reproducibility and results precision.