Validation strategy for an ED-XRF method to determine trace elements in a wide range of organic and inorganic matrices based on fulfilment of performance criteria

摘要

This work describes the approach used to validate a method based on the use of energy-dispersive X-ray fluorescence (ED-XRF) which should serve the purpose of determining routinely trace elements in organic and inorganic matrices in a wide range of mass fractions. A high energy ED-XRF (up to 100 kV), equipped with 3D Cartesian polarising optics was used. The novelty of the validation is that it is based in the fulfilment of performance criteria empirically established, and moving away for mathematical algorithms built in the ED-XRF software which frequently gave unrealistic results not fit for their intended purpose. The following performance characteristics were determined: limit of quantification (LoQ), repeatability, intermediate precision, standard uncertainty, trueness, working range and robustness; matrix effect and selectivity were also evaluated. The method was applied to the determination of 25 elements (Al, As, Ba, Br, Ca, Cd, Cl, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Ni, P, Pb, Rb, S, Se, Sr, Ti, Zn, Zr), in organic matrices and 12 elements (As, Br, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Zn,) in inorganic matrices and for mass fractions ranging from sub mg kg(-1) level up to percentages, depending on the specific element.