Neodymium determination in hard drive disks magnets using different calibration approaches for wavelength dispersive X-ray fluorescence

Abstract

Due to matrix effects and limitations in the calibration process for direct analysis of solids, the search for different calibration approaches is very important. This study is aimed to Nd determination in high-performance magnets from hard disk using direct solid analysis by wavelength dispersive X-ray fluorescence. Three univariate calibration methods were evaluated: multi-energy calibration, one-point gravimetric standard addition and two-point calibration transfer. These strategies employ an efficient matrix-matching method, minimizing the matrix effects related to the direct analysis of solids. The trueness values were calculated according to reference concentration by inductively coupled plasma optical emission spectrometry and the concentration obtained by univariate models. For almost all samples, the trueness values were within an acceptable range from 80 to 120%. Besides that, relative standard deviation values ranged from 3 to 27% for all cases and, the standard error ranged from 2 to 6% w w−1 Nd among the calibration methods. These parameters show the potential of these alternative calibration methods over traditional ones.