Milling effects upon quantitative determinations of chrysotile asbestos bythe reference intensity ratio method

As is well known from literature, the grinding process, which is an unavoid able step in sample preparation, may strongly modify the physical propertie s of chrysotile through amorphisation. The aim of this work is to establish the proper milling time to apply to the samples before all accurate X-ray powder diffraction quantitative analysis. We have used the RIR (reference i ntensity ratio) analytical method, based on the measurement of the ratio I/ I-s between the intensity of the strongest line of an analyte and the inten sity of the analytical peak of a standard material, when they are thoroughl y mixed 50:50 by weight. We have studied how the RIR value changes as a fun ction of the milling time of the sample and how the accuracy of this: quant itative method is affected. (C) 2000 International Center for Diffraction D ata. [S0885-7156(99)00203-1].