Indirect spectrophotometric determination of silicate

An indirect spectrophotometric method has been developed for trace determination of silicate in aqueous samples. The silicate is converted into silicomolybdic acid and extracted into a mixture of 1-butanol and butyl acetate. The silicomolybdic acid is then decomposed with sodium hydroxide and the molybdenum(VI) reduced to molybdenum(III) with a Jones reductor, followed by reoxidation to molybdenum(VI) with iron(III). The resulting iron(II) is complexed with ferrozine, and the absorbance of the complex measured at 562 run. In this manner, submicroamounts of silicate can be determined.