Determination of molybdenum using polarographic catalytic current

Trace levels of molybdenum can be determined by differential pulse polarography, based on the catalytic effect of the molybdenum-PAR [4-(2-pyridylazo)-resorcinol] complex on the reduction of sodium bromate. The powerful oxidant, sodium bromate, increases the peak current for the reduction of the molybdenum-PAR complex by about 5 times. Under optimal conditions, molybdenum at the μg l−1 level can be easily determined. The detection limit is 0.22 μg l−1; the response is linear over the range of 1.0 × 10−8 to 1.0 × 10−7 M; and the relative standard deviation at 1.0 × 10−7 M molybdenum is 2.77%. Most cations do not interfere in the determination of molybdenum.