Novel spectrophotometric method for the determination of molybdenum in a PVA medium.

A novel spectrophotometric method for the determination of trace molybdenum in the presence of a large amount of tungsten was developed. This proposed method was based on the formation of a green charge-transfer polyoxometalate, molybdo-11-tungstophosphate-3,3',5,5'-tetramethylbenzidine-N-propanesulfonic, which was solubilized and stabilized in a PVA medium; the wavelength of the maximum absorption was at 660 nm. Beer's law was obeyed in the Mo concentration range of 0.04-1.6 microg ml(-1). The molar absorptivity was 1.35 x 10(4) l mol(-1) cm(-1). The developed method avoided the interference of W(VI), and was conveniently applied to analyses of some tungsten ores containing Mo(VI) with satisfactory results.