X-RAY-FLUORESCENCE DETERMINATION OF TRACE-ELEMENTS IN GEOLOGICAL-MATERIALS - AN ITERATIVE APPROACH TO COMPTON SCATTER CORRECTIONS FOR MATRIX ABSORPTION

Compton scatter corrections are widely used for trace element determinations in geological materials where elements heavier than iron commonly occur only in low concentrations and whose effects on matrix absorption are usually ignored. Problems with the Compton correction for absorption can be seen if the concentrations of these trace elements become anomalously large, perhaps up to a few percent, although the effects can actually become significant at only a few hundred parts per million. When this occurs the simple absorption relationship, estimated at the Compton wavelength, becomes distorted. An iterative algorithm is presented that corrects absorptions ratios at any wavelength as absorption edges are encountered during processing and in turn extends the Compton method to the accurate determination of anomalously high trace element concentrations.