Development of Exact Matrix‐Matching Inductively Coupled Plasma‐Optical Emission Spectroscopy for the Analysis of Cu and K in Infant Formula

In the present study, we have developed an exact matrix-matching inductively coupled plasma-optical emission spectroscopy (ICP-OES) as a low-cost alternative to the isotope dilution inductively coupled plasma-mass spectrometry (ICP-MS) method for accurate and precise measurements of nutrient elements K and Cu in infant formula. In spite of its high precision and accuracy, ICP-OES analysis of complex samples was not reliable due to biases originating from various matrix effects. The elaborated exact matrix-matching approach tested here demonstrated its potential to minimize biases due to matrix mismatch. The exact matrix-matching ICP-OES method was successfully validated by comparing the results with those from an isotope dilution ICP-MS method. Because the model provides reliable results without significant loss of precision, it will be an excellent choice for major element analysis in a complex sample, especially when isotope dilution is not applicable due to the lack of alternative isotopes or the high cost of enriched isotopes.