Theoretical Study of X-Ray Fluorescent Determination of Traces of Heavy Elements in a Light Matrix: Application to Rocks and Soils

The problem of quantitative x-ray fluoroscopic analysis of traces of a heavier element in a light matrix is considered. Radiation scattered by the sample is used as an internal standard. For the restricted system under investigation, a fairly rigorous theoretical treatment is possible. A mathematical expression is derived relating the intensity of radiation at the fluorescent peak to that scattered at a chosen wavelength in its vicinity and to the concentration of trace element present. It is independent of matrix composition. On the basis of this relationship, experimental calibration curves with a wide range of applicability were prepared for Zn, Cu, Ni, Cr, and V. The accuracy of the method is tested by analyzing two samples of silicate rock of known composition.