USE OF X-RAY-POWDER DIFFRACTION FOR DETERMINING LOW-LEVELS OF CHRYSOTILE ASBESTOS IN GYPSUM-BASED BULK MATERIALS - SAMPLE PREPARATION

An X-ray diffraction procedure for quantitative chrysotile asbestos an alysis in a gypsum-based matrix is discussed, The procedure includes c alibration standards preparation, an EDTA treatment to remove gypsum, sample milling, and X-ray diffraction analysis, The effect of each ste p is discussed. Morphological and crystal structural changes due to th e sample preparation procedure were also characterized using technique s such as SEM, IR, NMR and ICP. Through a statistically designed exper iment, it is demonstrated that-X-ray diffraction can be used as a reli able technique in gypsum-based matrices to determine chrysotile concen tration from 0.25% to 2.5% with a standard deviation of 0.07%.