Determination of nickel and cobalt in refined beet sugar by adsorptive cathodic stripping voltammetry without sample pretreatment

Nickel and cobalt have been analysed in refined beet sugar at the μg kg−1 level by adsorptive cathodic stripping voltammetry in the differential-pulse mode (DPCSV) at the hanging mercury drop electrode (HMDE) as their dimethylglyoxime complexes, M(DMG)2. Measurements were directly carried out on untreated sugar solutions. The performance of the procedure was compared with electrothermal atomic absorption spectrometry (ETAAS) applied to digested sugar samples, and showed in general better accuracy. The procedure was applied to the determination of these toxic elements in refined beet sugar samples, and concentrations below 50 μg kg−1 nickel and 10 μg kg−1 cobalt were found, which are much lower than the toxic levels of these elements.