Atomic Perspectives X-ray Fluorescence Spectroscopy, Part II: Sample Preparation

This installment of "Atomic Perspectives" is the second in a series describing the educational components and processes necessary in teaching and learning the technique of X-ray fluorescence (XRF) spectroscopy. Although three of the four states of nature (gas, liquid, and solid) are discussed briefly, the focus is on the sample preparation of bulk solid materials. Because of the advances in XRF instrumentation hardware and software as well as algorithm knowledge and selection for mathematical corrections, selection of an appropriate sample preparation technique is the major source of error in the most exacting quantitative analyses. The discussion begins with the fundamental assumptions necessary to prepare a bulk powder material for the best possible accuracy during quantitative analysis. Analysis of error is considered to show where sample preparation fits in the scheme of things. Then we discuss the physics involved during the excitation and emission processes and consider the major sources of error in preparing powders. Finally, the basics of grinding, pressing, and the fusion method of sample preparation are described.