Analytical capabilities of Energy Dispersive X-Ray Fluorescence for the direct quantification of iron in cocoa powder and powdered cocoa drink

The objective of this study was to develop and validate a quick and easy method for the quantification of iron by Energy Dispersive X-Ray Fluorescence (ED-XRF) in cocoa powder and powdered cocoa drink. Pellets of 6 g were prepared under 10 tons. Total time to analyze both sides of pelletized samples is 150 s. During this validation step, the iron concentrations obtained by ED-XRF were systematically evaluated against those obtained from inductively coupled plasma-atomic emission spectrometry. This feasibility study demonstrates the good potential of ED-XRF technique as an accurate, simple, cheap and rapid method. Indeed, ED-XRF method was found to be comparable to the reference one; furthermore, the bias between both methods was found to be not significantly different from 0. Robust relative repeatabilities and intermediate reproducibilities were found to be lower than 1.5%. The expanded uncertainties represent less than 12% of the median concentration of the validation samples.