Determination of mineral content in sugar bean, lentils and groundnuts sold by the roadside in Gaborone, Botswana

Abstract

Samples of raw lentils, sugar beans and groundnuts were bought from a street vendor by the roadside at Gaborone Bus Station. Sample preparation was carried out by microwave digestion process. The digests were analyzed for selected metals (Ca, Fe, Mg, Zn, Cd and Pb) using flame atomic absorption spectrophotometer (Varian Model 220 AAS). For the selected legumes, Lentils, Sugar beans and Groundnuts, mineral contents concentrations (mg/100g) of Ca, Fe, Mg, Zn, together with that of heavy metals Cd and Pb were determined. Data analysis using Statistical Package for Social Scientists (SPSS) gave concentrations as follows: Lentils (2.51 ±0.39, 1.75 ±0.05, 2.34 ±0.03, 4,15 ±0.03), Sugar Beans ( 5.24 ±5.73, 3.08 ±0.18, 1.95 ±0.21, 4.21 ±0.02) ,Groundnuts ( 5.65 ±0.12, 1.93 ±0.32, 2.49 ±0.11, 4.33 ±0.05) respectively for Fe, Mg, Zn and Ca. Cd concentrations were very low recorded as 6.01 x10 -5 ±1.85 x10 -6 , 5.61 x 10 -5 ±3.57 x10 -6 and 7.72 x10 -5 ±8.44 x10 -6 whereas for Lead (Pb) were recorded as 8.35 x 10 -4 ±9.19 x10 -6 , 1.94 x 10-3 ±1.54 x10 -3 and 2.61 x 10-3 ±3.30 x10 -4 respectively for the lentils, sugar beans and groundnuts. It is evident that the selected legumes have essential nutritional minerals even though appearing in lower concentrations, of which to some extend may compromise the nutritional quality of the samples. But as for possible contamination by toxic metals, there were no significant amounts recorded.