Determination of mercury in refined beet sugar by anodic stripping voltammetry without sample pretreatment
Departamento de Química Analítica, Facultad de Ciencias, Universidad de Valladolid, 47005 Valladolid, Spain.
Total mercury has been analysed in refined beet sugar at the μg kg−1 level by differential-pulse anodic stripping voltammetry (DPASV) at a rotating gold disk electrode (RGDE). DPASV measurements of mercury are based on its accumulation onto the RGDE as a Hg–Au amalgam and followed by the reoxidation of Hg(0) to Hg(II). Measurements were directly made on untreated sugar solutions. The DPASV procedure was compared with cold-vapour atomic absorption spectrometry carried out at a flow-injection mercury system when applied to digested sugar samples. The DPASV method has been demonstrated to perform conveniently for metal determination in beet sugar of good quality (low metal concentration) produced by Spanish sugar refineries. Mercury concentrations below 5 μg kg−1 were found in all commercial beet sugar samples analysed, which are much lower that the maximum permissible contents derived from the provisional tolerable weekly intake recommended by the World Health Organization.