Levels of selected heavy metals in canned tomato paste sold in Ghana

Abstract

Sixty-one samples of canned tomato paste comprising seven brands originating from three countries and sold in local markets in the Kumasi Metropolis of Ghana were analysed for levels of iron (Fe), zinc (Zn), manganese (Mn), cadmium (Cd) and lead (Pb) by flame atomic absorption spectrophotometry and for levels of mercury (Hg) by direct mercury analyzer. Mean heavy metal concentrations varied by brand, ranging from below the limit of detection (Cd) to a maximum concentration range of 1.68 ± 1.63 to 58.6 ± 14.5 µg g ⁻¹ (Fe). Estimated mean ranges of other heavy metals are 2.06 ± 0.62 to 8.52 ± 0.68 µg g ⁻¹ (Zn), 2.62 ± 0.33 to 5.75 ± 0.47 µg g ⁻¹ (Mn), 0.070 ± 0.003 to 0.116 ± 0.012 µg g ⁻¹ (Pb) and 0.011 ± 0.001 to 0.102 ± 0.001 µg g ⁻¹ (Hg). Assessed metal levels in five brands were below the WHO/FAO permissible levels. Results of the one-way analysis of variance (ANOVA) conducted on the data suggested no significant variations (P > 0.05) in the concentrations of the metals in the same brands of canned tomatoes.

Keywords:

• canned foods
• vegetables
• heavy metals

Acknowledgements

Special thanks to the Chemistry Department, KNUST, Kumasi, for its financial support.