Optimization and Validation Procedure for Elemental Composition of Fresh and Pasteurized Milk in Pakistan Employing Microwave Digestion Followed by ICP-OES: a Contribution to Risk Assessment

Inductively coupled plasma-optical emission spectrometry method for determination of macroelements (Ca, Mg, K, P, Na), trace elements (Cr, Cu, Fe, Mn, Se, Zn), non-essential element (Al), and toxic heavy metals (As, Cd, Pb) in fresh milk (n = 24) and pasteurized milk (n = 15) was optimized and validated. Analytical lines with low matrix affects and free from spectral interferences were selected for optimization and validation studies. Accuracy and precision were performed on certified milk samples and percent relative standard deviation (%RSD), and recovery results are in compliance with FDA guidelines for inductively coupled plasma-optical emission spectrometry (ICP-OES) methods for elemental composition in food stuffs. Significantly higher concentration of Al was found in both types of milk samples as compared with recommended standard for milk. No significant difference was found between the concentration of Pb and Cd in both samples. A strong positive correlation was found between Cu-Fe and Al-P. Correlations between other elements within each of analyzed samples were also found. The results indicate that particular attention should be paid to Al and Pb residues to control and confirm the absence of possible toxicological risks.