COBALT IN DUTCH MILK POWDER - DETERMINATION BY DIFFERENTIAL-PULSE ADSORPTIVE CATHODIC-STRIPPING VOLTAMMETRY

Details are given of a polarographic procedure for determining cobalt (Co) in milk powder. The method is based on concentration of Co2+ from a solution of the dissolved ash constituents onto a hanging mercury drop as its dimethylglyoxime complex and subsequent measurement of the current resulting from reduction of Co2+ by a cathodic scan. Fifty-three whole-milk powders, derived from various parts of the country and produced in different periods of the year, were analysed for Co. The average content was 3.3 ng Co per g total solids. Milk was calculated to contain approximately 0.4-mu-g Co/kg. Statistical analysis of the data indicated an unexplained regional effect (p < 0.05), but no seasonal effect on the Co content of milk powder.