Spectrophotometric Determination of Molybdenum in Some Alloys and Steels Using Quinalizarin and Cetylpyridinium Chloride

A new sensitive and rapid method is proposed for the spectrophotometric determination of molybdenum in some cobalt and nickel base alloys and steels. The procedure is based on the formation of a molybdenum(VI)-quinalizarin complex in an aqueous micellar solution of cetylpyridinium chloride (CPC) at pH 3.2-4.2. Beer′s law is obeyed over the range 0.05-0.60ppm of molybdenum. The apparent molar absorptivity of the complex is (1.27±0.01)×105l mol-1 cm-1 at 580nm and the sensitivity index is 0.0007μgcm-2 of molybdenum. The experimental factors which affect the color reaction were investigated throughly. The method is free of interference from most of the common metal ions.