Comparison of Two Sample Preparation Methods for X-Ray Fluorescence Spectrometry in the Determination of Ni and Cr

Abstract

Pressed powder pellets and fused beads or glass disks are routinely used in X‐ray fluorescence spectrometry for the determination of major and trace elements, respectively, in geological materials. In order to evaluate the performance of these two sample preparation methods, we determined Ni and Cr concentrations of fourteen RMs from Japan, France and South Africa, and eighty‐five igneous and three sedimentary rock samples from Mexico in both powder pellets and glass beads. We also computed new values of statistical parameters for RMs from an outlier‐based multiple‐test method and compared them with the literature mean and confidence limit values. The results showed that the multiple‐test method provided more reliable central tendency and dispersion parameters for RMs than those obtained previously from the two or three standard deviation method, or from robust methods. The powder pellet and fused bead sample preparation methods provided consistent results for Ni and Cr at concentration levels > 50 μg g−1 in this application; for lower concentration levels, however, these methods showed somewhat greater differences. For quantitative comparisons, both ordinary and weighted least‐squares linear regression models were used to show that the two sample preparation methods provided generally unbiased results.

Solute geothermometry of springs and wells of the Los Azufres and Las Tres Vírgenes geothermal fields, Mexico

“…Verma and L. Díaz-González (unpublished data) have developed a computer program, named DODESYS, by incorporating the recently available new, precise, and accurate critical values (Verma and Quiroz-Ruiz 2006aVerma et al 2008b;Verma 2009a) to render the most reliable statistical inferences. This objective outlier rejection statistical method has been successfully applied in many studies (Velasco et al 2000;Guevara et al 2001;Velasco-Tapia et al 2001;González-Ramírez et al 2009;Marroquín-Guerra et al 2009;Pandarinath 2009;Torres-Alvarado et al 2011;Verma 2009b;Verma et al 2009aVerma et al , 2009bVerma et al , 2009c. Discordant outlier-free, normally distributed chemical data of fluids of springs and drilled geothermal wells were used for the estimation of reservoir temperatures from almost all available solute geothermometers (SolGeo computer program by Verma et al 2008a).…”

Atomic spectrometry update—X-ray fluorescence spectrometry

“…They realised that the simple approach used by many analysts for some time of treating the gain as a negative loss on ignition in the calculation of theoretical influence coefficients works well. Verma et al 145 compared fused bead and pressed powder pellet preparation methods for the determination of Cr and Ni in geological samples using igneous and sedimentary reference materials. As expected, both preparation techniques gave consistent results at concentrations >50 mg g À1 with greater differences for lower concentration levels after assessment by both ordinary and weighted least squares linear regression models.…”