Extractive spectrophotometry of the molybdenum (III) 1,10-phenanthroline thiocyanate and 2,2'-bipyridyl thiocyanate complexes

New extraction spectrophotometric methods for the determination of small amounts of molybdenum have been developed, using thiocyanate and 1,10-phenanthroline or 2,2'-bipyridyl as reagents in the presence of chlorostannous acid. Extracts of the ternary complexes of tervalent molybdenum in 1,2-dichloroethane obey Beer's law in the range 1-10 mug/ml at 525 nm. A 10-fold excess of iron and vanadium and 100-fold excess of tungsten, phosphorus and silicate do not interfere.