Validation of quick measurement of mineral nutrients in milk powders: comparison of energy dispersive X-ray fluorescence with inductively coupled plasma-optical emission spectroscopy and potentiometry reference methods

Energy dispersive X-ray fluorescence method is a good candidate to be implemented close to production lines of fortified milk powders, in order to ensure their quality control. In this study an energy dispersive X-ray fluorescence (EDXRF) method was tested as a simple, fast (< 8 min/pellet) and simultaneous method for the quantification of a series of macroelements (Na, Mg, P, Cl, K and Ca) and micronutrients (Fe, Cu and Zn) from fortified milk powders. Calibrations were established using results from reference methods results (inductively coupled plasma-optical emission spectroscopy and potentiometry for chloride). Twenty-one calibration samples were selected to cover uniformly the expected concentration ranges for each element. The EDXRF results were validated by a strict and systematic comparison with data obtained from the reference methods on a set of thirty further and independent samples. This study confirmed that EDXRF is a fast and reliable method of choice for quality control analyses Na, Mg, P, Cl, K, Ca, Fe, Cu and Zn in milk powders allowing better process control and reaction in case of deviation. Although manganese is detected, its quantification was not possible due to unacceptable statistical performance characteristics.