Assessment of trace metal contents in chocolate samples by Atomic Absorption Spectrometry

Trace metals (Pb, Cd, Ni, Fe, Cu, Zn and Mn) were assessed using Atomic Absorption Spectrophotometry (AAS) in 32 commonly consumed cocoa products (chocolates) prepared by different national and multinational companies. Microelement contents studied varied significantly in all type of chocolates (P < 0.01). The concentrations of Pb and Cd in cocoa powder were found to be highest, 1400 and 190 μg/L respectively, whereas mean concentrations of these elements in cocoa-based chocolates were found to be 306 and 46.4 μg/L respectively. In sugar-based chocolates, the mean concentrations of Pb and Cd were 209.8 and 40.7 μg/L, respectively, whereas in samples of milk-based chocolates they were found to be 88 and 33 μg/L respectively. Frequent consumption of chocolates enhances the intake of Pb and Cd metals in children. Weekly intake of toxic metals Pb, Cd and Ni were also calculated. Mean concentrations of Pb and Cd were found below the provisional tolerable weekly intake as defined by FAO/WHO. All essential elements were assessed for their weekly intake with the dietary reference intakes (DRI), whereas the percentage contributions of Pb and Cd were calculated from provisional tolerable daily intake (PTDI). Results were validated through the analysis of certified reference materials and determined metals concentrations were in good agreement with certified levels. Data was interpreted through cluster analysis and pattern recognition.