Determination of copper and arsenic in refined beet sugar by stripping voltammetry without sample pretreatment

Copper and arsenic have been analysed in refined beet sugar at the microgram kg-1 level by anodic stripping voltammetry (copper) and cathodic stripping voltammetry (arsenic) in the differential-pulse mode (DPASV and DPCSV) at a hanging mercury drop electrode (HMDE). DPCSV measurements of arsenic are based on its accumulation onto the HMDE as an intermetallic Cu-As compound followed by the reduction of As0 to arsine in hydrochloric acid medium. Measurements were directly carried out on untreated sugar solutions. The performance of the procedures was compared with electrothermal atomic absorption spectrometry and stripping voltammetry applied to digested sugar samples, and showed in general better accuracy. The procedures were applied to the determination of these toxic elements in commercial beet sugar samples of concentrations below 50 micrograms kg-1 copper and 15 micrograms kg-1 arsenic were found, which are much lower that those allowed by the current regulations.