Development and Validation of an ED-XRF Method for the Fast Quantification of Mineral Elements in Dry Pet Food Samples

A simple and fast method for the quantification of a series of macro elements (Na, Mg, P, Cl, K and Ca) and trace elements (Mn, Fe, Cu and Zn) by Energy Dispersive X-Ray Fluorescence (ED-XRF) was developed and validated using samples of commercial dry pet foods. All samples were systematically analyzed by reference methods (i.e. Potentiometry for chloride and Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) for other elements) and by ED-XRF. A calibration set of 33 samples was selected to uniformly cover the concentration ranges of each element and their reference method values were used to calibrate the ED-XRF device. A second set (the validation set) was composed of 46 other samples, which were analyzed as unknowns. During this validation step, the elemental concentrations obtained by ED-XRF were systematically evaluated against those obtained from the reference methods. Using robust statistics, for the 10 investigated analytes, the bias between both methods was found to be not significantly different from 0 and the relative uncertainties RSD(u) were found to be lower than 15 %. This study demonstrated that ED-XRF is a fast and reliable method for minerals quantification in dry pet foods.