Accurate quantitative measurements of asbestos in XRPD analysis

X-ray Powder Diffraction (XRPD) quantitative analysis of fibrous substances like asbestos, is strongly influenced by systematic errors due to preferred orientation, as a consequence of their morphology. In the present work we have compared the accuracy of quantitative measurements performed by using the Internal Standard (IS) method and the Reference Intensity Ratio (RIR) method in the analysis of the same diffractographs. Both these analytical methods are based on the same principle but the data analysis procedures are different. We have particularly studied how, in the RIR case, the evaluation of several diffraction lines of both phases, standard and unknown, increases the accuracy of a quantitative determination, balancing the different effect due to systematic errors on the measurements of distinct peaks.