Development of undersized (12.5 mm diameter) low‐dilution glass beads for X‐ray fluorescence determination of 34 components in 200 mg of igneous rock for applications with geochemical and archeological silicic samples

Abstract

A low‐dilution, undersized (12.5 mm diameter) glass–bead technique was developed for X‐ray fluorescence determination of 34 components (Na2O, MgO, Al2O3, SiO2, P2O5, K2O, CaO, TiO2, MnO, Fe2O3, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Cs, Ba, La, Pr, Nd, Sm, Gd, Dy, Er, Yb, Hf, W, and Pb) in precious silicic samples for geochemistry and archeology. This preparation was consolidated based on the properties of the specimen, including disk formability and detachability from a small crucible, through variation of the amounts of the two samples (basaltic and granitic rocks) and releasing reagent. The specimen was prepared by fusing a mixture of 200 mg of powdered sample, 200 mg of lithium tetraborate as a flux, and 60 µl of 18.42 mass% lithium chloride solution as a releasing agent in a small platinum crucible. Calibration curves were drawn using synthetic calibration standards, which were prepared by compounding chemical reagents, such as oxides, carbonates, and diphosphates containing analytes. The calibration curves showed good linearity with correlation coefficient values greater than 0.990. Using the proposed method, we determined 34 components in five igneous rock reference samples. The results were in agreement with the recommended values, accounting for uncertainties. With this method, preparation requires only small amounts of the powdered sample and alkali flux; however, still allowing for determination of many analytes, which is advantageous when dealing with limited quantities of precious samples. The present method has potential applications in the chemical characterization of various geological and archeological samples. Copyright © 2015 John Wiley & Sons, Ltd.

Approaches to solid sample preparation based on analytical depth for reliable X‐ray fluorescence analysis

“…prepared 6‐mm‐diameter glass beads with a 1:10 sample‐to‐flux ratio using small geological materials (15 mg) to assay 10 major oxides . In addition, we developed two preparation techniques: (1) micro‐glass beads (approximately 3.5 mm in diameter and 0.8 mm in height) were prepared from 1.1 mg of silicic sample and 11.0 mg of alkali flux for the determination of major oxides, and (2) low‐dilution, undersized (12.5 mm in diameter) glass beads were prepared from 200 mg of powdered sample and 200 mg of alkali flux to quantify 10 major oxides and 24 minor elements …”

“…In contrast, the synthetic standards are suitable for the preparation of glass beads because of the fusion process because the synthetic standard is made by mixing some chemical reagent. For example, the technique was used for the XRF determination of 42 components in acidic igneous rocks, 34 components in rocks, and the major oxides in ancient pottery …”

“…The validation is performed by analyzing CRMs and RMs with the proposed analytical process and comparing the results to the certified values. For example, the preparations of glass bead using rock and pottery samples for XRF analysis were validated using several geochemical references issued by the GSJ. Furthermore, the powder pellet preparation technique for the XRF analysis of fly ash was validated using a CRM of coal fly ash issued by NIST.…”

X-ray fluorescence determination of Cs, Ba, La, Ce, Nd, and Ta concentrations in rocks of various composition

“…Ichikawa et al . developed a technique allowing to determine 34 elements by XRF, including Cs, Ba, La, and Nd.…”

“…Ichikawa et al [10] developed a technique allowing to determine 34 elements by XRF, including Cs, Ba, La, and Nd. Authors used samples of 12.5 mm diameter, fused with flux (1 : 1 ratio).…”