Comparison of wavelength‐dispersive X‐ray fluorescence spectrometry and inductively coupled plasma optical emission spectrometry for the elementary determination in plants through the accuracy profile method

Abstract

Accuracy profile is a graphical method, which allows to validate an analytical method. It defines a validity of a concentration range for a given accuracy. With this tool, quantitative determinations of macroelements and microelements (Al, Ca, Fe, K, Mg, Mn, Na, P, S, and Zn) in plant samples were evaluated by the use of a wavelength‐dispersive X‐ray fluorescence instrument. The method uses a simple preparation procedure with only drying, grinding, and pressing samples. The measured samples were reference materials with known mineral contents. The calibration procedure was established by employing plant materials issued from interlaboratory studies. Matrix effects were corrected by employing the method of the influence coefficients on the basis of the computerized routine program linked to the equipment. The accuracy profiles of the method show the measurements (trueness and precision) collected under intermediate precision conditions and aim to compute an acceptability interval where a known proportion of future results will be located. The various types of accuracy profile behavior were exemplified. In comparison with an inductively coupled plasma optical emission spectrometry method, the use of X‐ray fluorescence offers a good alternative, faster, and better precision. Inversely, inductively coupled plasma optical emission spectrometry offers an approach well suited for the trueness of measurements with very low matrix effects.