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 analysis in a gypsum-based matrix is discussed. The procedure includes calibration standards preparation, an EDTA treatment to remove gypsum, sample milling, and X-ray diffraction analysis. The effect of each step is discussed. Morphological and crystal structural changes due to the sample preparation procedure were also characterized using techniques such as SEM, IR, NMR, and ICP. Through a statistically designed experiment, it is demonstrated that X-ray diffraction can be used as a reliable technique in gypsum-based matrices to determine chrysotile concentration from 0.25% to 2.5% with a standard deviation of 0.07%.