A NOVEL METHOD TO ASCERTAIN SAMPLE MASS THICKNESS AND MATRIX EFFECTS FOR X-RAY-FLUORESCENCE ELEMENT DETERMINATIONS

An x-ray fluorescence method was developed for the determination of both trace and major elements in environmental mental samples that are primarily of geochemical origin. For analysis, unweighed finely pulverized sample material is lightly compressed to a mass thickness between 0.1 and 0.4 g cm-2. The method utilizes the relative intensities of two incoherent and one coherent scattered excitation radiation to ascertain the sample mass thickness and the photoelectric cross-section of the sample for the excitation radiation. This information is employed to calculate matrix absorption and enhancement effect corrections required for the individual element determinations. The intensity of one of the incoherently scattered radiations serves as an internal standard for all of the element determinations. The capability of the method has been demonstrated with three US National Institute of Standards and Technology reference materials. The concentrations of sixteen trace elements (Mn, Ni, Cu, Zn, Ga, As, Se, Br, Rh, Sr, Y, Zr, Nb, Ba, Pb, and Th) and four major elements (K, Ca, Ti, and Fe) were determined from one x-ray spectrum which was acquired over a 1000 s counting interval.