[Schiff base type onno spectrophotometric determination of magnesium].

By condensing hydrazide salicylic acid with o-hydroxy carbonilic compounds it was obtained 2--hydroxy acetophenon--salicyl hidrazina, Schiff base--type ONNO. These Schiff bis bases present a good capacity of complexing the Mg (II) ions. The above mentioned Schiff base forms complex with Mg (II) cation, with maximum absorbance at 386 nm, and molar absorbtivity (epsilon) = 6.27 x 10(4) mol-1.L.cm-1. The complex with Mg (II) presents a maximum stability at pH = 9.6 - 10.0. The calculated apparent stability constant is K = 3.18 x 10(3). The absorbance is proportional to Mg (II) concentration in the range of 10-60 mg/mL. In this range, the Lambert--Beer law is respected, the linearity coefficient being 0.9818, SD = 0.83, RSD = 0.84 (n = 6). The results obtained for spectrophotometric determination of Mg (II) using this Schiff base as reagent were successfully applied to pharmaceutical products containing Mg (II) cation.