Voltametric technique for measurement of heavy metals in canned fish

Heavy metals such as cadmium and lead do no degrade and/or metabolize in vital systems, and accumulate in different organs of the body such as muscles, adipose tissue, bones, and joints. In this study, we measured concentration of four elements of copper, zinc, cadmium, and lead in canned fish.
At first, 54 canned fish samples were purchased from local market in Tehran (capital city of Iran). For analysis, 2 g of each sample was weighted and mixed with 65% nitric acid. The mixture was heated at 450 °C, and dry ash was used for voltametric analysis.  In this work, direct determination of heavy metals in canned fish was carried out by differential pulse anodic stripping voltammetry (DPASV) technique at hanging mercury dropping electrode (HMDE).
Results and Quantitative measurement limits were 0.045, 0.006, 0.004, and 0.013 mg/kg for zinc, cadmium, lead, and copper, respectively. The results showed that mean concentration was 1.41 ±0.948 mg/kg for zinc, 0.050 ±0.038 mg/kg for cadmium, 0.146 ±0.119 mg/kg for lead, and 0.082 ±0.065 mg/kg for copper. The mean value obtained for each heavy metal was compared with the values authorized by the National Standard Organization of Iran, World Health Organization, and Food and Agriculture Organization, through which all concentrations were below the maximum permitted values. Concentration of cadmium, copper, and zinc showed significant relationships with brand of the samples. This indicates significant differences in concentration of these elements among different brands, which needs to be investigated by the competent authorities.