Most essential elements present in infant formula have received very little attention. In this study, an improved methods was validated for the determination of some essential and toxic elements (cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), nickel (Ni), tin (Sn) and zinc (Zn)) using inductively coupled plasma optical emission spectrometer (ICP OES) and graphite furnace atomic absorption spectrometer (GFAAS). The validation procedure was applied for the evaluation of the limit of detection, and quantification, recovery, linearity, accuracy, and measurement uncertainty. The method showed that the detection limits varied between 0.001 and 0.217 mg/kg, and the quantification limits varied between 0.005 mu g/kg and 1 mg/kg. The mean recoveries at different spiking levels varied between 82.74 +/- 0.87 and 116.31 +/- 3.08%. The method accuracy was confirmed by using three reference materials (RM), and all obtained results were within satisfactory ranges and had acceptable Z-score values. The method precision, in terms of relative standard deviation, was below 8.76%. The method uncertainty expressed as expanded uncertainty was found to be <= 27.3%. The proposed procedure was applied to the analysis of Eight-Three samples covering eighteen different brands of popular milk formula in Egypt to assess whether the intakes complied with the permissible levels for toxic metals and recommended desired levels for essential elements. The results showed that the concentration ranges, in mg/kg, were as follows: < 0.005-0.017 (Cd), < 1-8.76 (Cu), 32-86.87 (Fe), < 1-7.11 (Mn), and 22.46-87.3 (Zn).On the other hand, all tested samples were free from any detectable amount of Cr, Co, Ni, and Pb. The daily intakes of essential elements (Cu, Fe, Mn, and Zn) are lower than the recommended desirable levels (infant's nutritional requirement). Similarly, the weekly intakes of Cd were also significantly below the recommended tolerable levels.
