Determination of the level of some essential and toxic metals by Inductively Coupled plasma optical emission spectrometry in five commercially available brands of powdered milk in Bahir dar, Ethiopia

ABSTRACT In this thesis the concentration of some selected essential and toxic metals in five commercially available brands of powdered milk in Bahir dar, Ethiopia using Optima 8000 ICP – OES .The samples were digested by using wet digestion optimized procedure using mixture of 6 ml of HNO3 (69-72%) and 3.5 ml HClO4 (70%) for 3 h at a temperature of 270 OC in digestion block. The concentration of metals determined in μ g/g dry weight in Nido powdered milk Mg (741.3), Ca (7614), Na (2869), K (7382), Zn (79.2) and Pb (15.6). In coast powdered milk Mg (609.9), Ca (5971), Na (2405), K (8366), Zn (41.6), Pb (15.1). In Anchor powdered milk Mg (519.5), Ca (3749). Na(1770), K (5634), Zn (85.9) and Pb (15.7). In Lorado powdered milk Mg(235.2), Ca(1053), Na(1096),K(5266), Zn(47.4) and Pb (17.5) and finally Lato powdered milk Mg(226.8), Ca(636.8), Na(1553),K(5646), Zn(35.5) and Pb(14.5). K has the highest mean concentration from all metals in five samples with range of (8366 – 5266) and the minimum were Pb with ranges of (17.5 – 14.5). The % recoveries range from 81.44 – 116.80 and %RSD of metals was less than 10%. The study also shows that ranks of powdered milk samples for each metals coast were 1st by K, Nido were also 1st by Ca and Lato last by Pb. Finally the mean concentrations of most metals in this study are comparable with the literature reported values