Practical XRF Calibration Procedures for Major and Trace Elements

Abstract

Different calibration procedures for the determination of major and trace elements by XRF analysis are presented and discussed. Empirical calibration curves comparing intensities with concentrations can be used for the analysis of samples with limited variations of the matrix composition. However, a general‐purpose calibration procedure that is applicable to a larger variety of matrix types and covering wider ranges of the analyte concentration is usually more desirable. This paper presents practical and simple calibration procedures for the determination of major and trace elements that will allow one to adapt any mathematical model to any set of experimental data while producing the maximum of accuracy in the final results. It is also shown how to calculate from multi‐element standards a practical intensity of the pure analyte, thus eliminating the requirement for a pure analyte specimen.

Evaluacion de la bioacumulacion de cobre en Euglena gracilis mediante la tecnica de fluorescencia de rayos X

“…Para la calibración del sistema y el análisis cuantitativo, se irradió bajo las mismas condi-ciones referencias certificadas de diversos materiales biológicos del National Institute for Standards and Technology (NIST) SRM 1573a (hojas de tomate), y la Agencia Internacional de Energía Atómica (AIEA) SRM 16 (acelga), SRM 392 (alga), SRM 286 y SRM 336 (líquenes), y SRM 359 (col), estos últimos usualmente empleados en estudios con biomonitores con técnicas de rayos X patrocinados por la AIEA (Cervantes et al, 2008). La intensidad de rayos X de los elementos detectados en las muestras se midió con el programa AXIL (Vekemans et al, 1994) y el análisis cuantitativo se realizó siguiendo el procedimiento descrito por Rousseau et al (1996). La absorción de los iones de Cu 2+ en los tejidos de E. gracilis, se calculó usando el factor de bioacumulación (FBA) que proporciona información sobre la habilidad del vegetal de acumular metales con respecto a la concentración de metales presentes en la solución nutritiva.…”

The Quest for a Fundamental Algorithm in X-Ray Fluorescence Analysis and Calibration

“…Clearly, the mathematical model proposed by Sherman is imperfect, but no model can account totally for all the subtleties of instrument response and X-ray interactions within the specimen. Nevertheless, experience shows that the model performs very well in practice [29] if all of these approximations are compensated by using an appropriate calibration procedure [3], as illustrated below. Willy de Jongh [11] was the first in 1973 to propose the philosophy of this calibration procedure that compares measured intensities to calculated intensities (he called them unrealistically "apparent concentrations").…”

“…Indeed, even if the absolute value of intensities I i and I iM vary because of the instrumental drift, their ratio remains constant [3].…”

“…When a theoretical analytical method is implied, a special calibration procedure [2,3] must be used, because it is well known that theory cannot account for the variations of all instrumental parameters. An innovative calibration procedure, comparing measured intensities to calculated ones, is then proposed.…”

Trace metal contaminants in sediments and soils: comparison between ICP and XRF quantitative determination

“…WD-XRF is a fast and reliable solution that covers a large part of the periodic table, in addition to having a field of application ranging from % up to ppm (Rousseau et al 1996).…”