Determination of molybdenum in steels by differential-pulse polarography of the 8-hydroxyquinoline-molybdenum(VI) complex

The 8-hydroxyquinoline-Mo(VI) complex has a reduction half-wave potential of –0.380 V vs. SCE in 1 M NaNO3-0.01 M HNO3. Iron only interferes at concentrations higher than 1.5 × 10–4M in the sample. This effect can be avoided with acetic acid. A method for the determination of molybdenum in steel based on catalytic reduction of the 8-hydroxyquinoline-Mo(VI) complex is described. A linear calibration is obtained for a concentration range from 10–8 to 10–6M. The detection limit is about 10–10M of Mo(VI).