Spectrophotometric Determination of Calcium with Glyoxal Bis(2-hydroxyanil) -On the Color Stability-

Abstract

Since red calcium-glyoxal bis(2-hydroxyanil) (GHA) complex is unstable in various solvent media, several experiments have been carried out to find appropriate condition for the quantitative color development. Absorbances of the reagent blank and calcium-GHA in 50% water25% ethanol-25% 1-butanol were measured at 0.35° C for 0-420 min. Satisfactory results were obtained when the solution, 0. O^2- N in sodium hydroxide, O.01% with respect to GHA and 50% with respect to the solvent mixture of ethanol and 1-butanol (1: 1), was kept at 0° C for 30-50 min before absorbance measurement.