Determination of essential and toxic total elements in premature human milk by inductively coupled plasma mass spectrometry (ICP-ORC-MS), using an octopole reaction cell

Abstract

The analytical potential of a quadrupole ICP-MS instrument equipped with an octopole reaction cell for the multielemental determination of essential (Cr, Mn, Fe, Co, Cu, Zn, Se and I) and toxic (Al, Cd and Pb) elements in whole premature breast human milk and premature infant formulae was demonstrated. Milk samples were digested using a microwave assisted digestion method in order to destroy the organic matrix. Different parameters affecting the octopole reaction cell were optimised in order to minimize/remove polyatomic interferences caused by argide species from the ICP. The accuracy of the proposed method was tested by analysing a milk powder reference material (BCR 063R) with satisfactory results. The detection limits in a synthetic matrix obtained using a collision cell ranged from 0.5 ng g⁻¹ to 11 ng g⁻¹ for the elements under study. After validation the method was applied to the multielemental analysis of premature human milk samples (after 28–32 gestational weeks) at three different lactating stages during the first month after birthday, and to formula milks commercially available for premature newborns. Results of total concentrations of the above mentioned elements in the two sample types compared here (human milk and formula milk) are discussed. Important differences between human and formula milk in their respective contents of essential elements are shown and the nutritional significance of such differences is highlighted.