Oxine complex of molybdenum

Molybdenum was reported to be precipitated quantitatively by 8-hydroxyquinoline in the pH range 3.3–7.6, the precipitated compound having the composition MoO₂(ox)₂. The pH range reported and the composition of the complex do not seem to be compatible with present knowledge of the pH stability of anionic and cationic molybdenum. It is now shown that under defined conditions, the precipitate is not formed at pH values higher than 2.24. In several estimations of other metals, molybdenum was masked by using a complexone at high pH values. It is now pointed out, that maintaining the solution at high pH value is itself sufficient and no other external complexing agent is necessary for masking molybdenum.