Determination of Co, Cu, Fe, Hg, Mn, Sb, Se and Zn in milk samples

Abstract

Concentrations of Co, Cu, Fe, Hg, Mn, Sb, Se and Zn in IAEA milk (dry) standard A-11 were re-evaluated with the help of instrumental and radiochemical neutron activation analysis (NAA). The results show reasonably good agreement for Co (5.1 ± 0.55 ng/g) and Zn (34 ± 2.5 μg/g), in relation to the recommended values. For Cu (374 ± 15 ng/g), Fe (2.4 ± 0.34 μg/g) and Mn (250 ± 20 ng/g); the results obtained are lower than the reported values. Cu, Mn, and Zn were cross-checked by atomic absorption spectrophotometry (AAS). The results, Cu = 331 ± 27 ng/g, Mn = 302 ± 62 ng/g, and Zn = 35 ± 1 μg/g, fall within the range of mean values obtained by NAA. For Hg and Se, using instrumental NAA, only upper limits could be indicated; because of the low levels of concentrations of Hg and Se on one hand, and high content of P (9100 μg/g) in A-11 milk standard on the other, NAA coupled with radiochemistry is to be preferred for these two elements. In pooled human milk, in addition to Cu and Mn (radiochemical) and Co, Fe, Sb and Zn (instrumental), Hg and Se could also be determined non-destructively because of the favourable Hg/P and Se/P ratios in this matrix.