Validation of Efficiency Method for Heavy Metals Determination in Kola Nuts (Cola nitida Schott & Endl.) from Côte d’Ivoire

Aims: The current study targets the achievement of a reliable process for the determination of heavy metal contents in kola nuts, namely cadmium, mercury, and lead, for better appreciation of the risks incurred from the consumption of such food products.

Study Design: kola nuts collected from different stakeholders (planters, collectors, stores and centers) were analyzed after the validation of the proposed analytical method.

Place and Duration of Study: Central Laboratory for Food Hygiene and Agro-Industry, LANADA in Abidjan, Côte d’Ivoire, running 2018.

Methodology: Two references were used for the validation of the analytical method, namely the French standard NF V 03-110 and the European directive 2001/22/EC. The assays were achieved with an flame Atomic Absorption Spectrophotometer (AAS). The heavy metal contents of some samples collected from different sampling place were then determined

Results: From the data, a significant regression chart was recorded for the heavy metals detection graphs, with significant correlation coefficients (R²˃ 0.99). The linearity domain was validated between 0.5 μg/L and 1.5 μg/L for cadmium, 15 μg/L and 45 μg/L for lead and from 10 μg/L to 100 μg/L for mercury. In addition, the LOD were 0.03 μg/L, 1.85 μg/L and 2.92 μg/L, while the LOQ were 0.07 μg/L, 6.52 μg/L and 3.32 μg/L for cadmium, lead and mercury, respectively. The relative standard deviations of the repeatability and reproducibility assays are below 4%, whereas standard additions of heavy metals are fully recovered, with percentages close to 100%. Contents of cadmium, lead and mercury in kola nuts are respectively valued at 22.97±9.01 μg/kg, 1065.57±613.76 μg/kg and 33.88±31.58 μg/kg from the farmers and 24.99±7.79 μg/kg, 296.51±98.18 μg/kg and 39.74±34.66 μg/kg from the storage centres.

Conclusion: This analytical method could help in ensuring effective sanitary control at different critical points of kola nut distribution channel for promoting a good management of the toxicity concerns in such products.