Statistically Coherent Calibration of X-Ray Fluorescence Spectrometry for Major Elements in Rocks and Minerals

Verma, Surendra P. y Verma, Sanjeet K. y Rivera Gómez, María Abdelaly y Torres Sánchez, Darío y Díaz González, Lorena y Amezcua Valdez, Alejandra y Rivera Escoto, Beatriz Adriana y Rosales Rivera, Mauricio y Armstrong Altrin, John S. y López Loera, Héctor y Velasco Tapia, Fernando y Pandarinath, Kailasa (2018) Statistically Coherent Calibration of X-Ray Fluorescence Spectrometry for Major Elements in Rocks and Minerals. Journal of spectroscopy, 2018. pp. 1-13. ISSN 2314-4939

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Resumen

Weappliedboththeordinarylinearregression(OLR)andthenewuncertaintyweightedlinearregression(UWLR)modelsfor thecalibrationandcomparisonofaXRFmachinethrough59geochemicalreferencematerials(GRMs)andaprocedureblank sample. The mean concentration and uncertainty data for the GRMs used for the calibrations (Supplementary Materials) (available here) filewere achieved from an up-to-date compilation of chemical data and their processing from well-known discordancy and significance tests. The drift-corrected XRF intensity and its uncertainty were determined from mostly duplicate pressed powder pellets. The comparison of the OLR (linear correlation coefficient r∼0.9523–0.9964 and 0.9771– 0.9999, respectively, for before and after matrix correction) and UWLR models (r∼0.9772–0.9976 and 0.9970–0.9999, respectively) clearly showed that the latter with generally higher values of r is preferable for routine calibrations of analytical procedures. Both calibrations were successfully applied to rock matrices, and the results were generally consistent with those obtained in other laboratories although the UWLR model showed mostly narrower confidence limits of the mean (slope and intercept)orloweruncertaintiesthantheOLR.Similarsensitivity(∼2.69–46.17kc·s1·%1 fortheOLRand∼2.78–59.69kc·s1·%1 for the UWLR) also indicated that the UWLR could advantageously replace the OLR model. Another novel aspect is that the totaluncertaintycanbereportedforindividualchemicaldata.Iftheanalyticalinstrumentswereroutinelycalibratedfromthe UWLR model, this action would make the science of geochemistry more quantitative than at present.

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