On the use of X-ray powder diffraction for determining low levels of chrysotile asbestos in gypsum-based bulk materials: use of a synchrotron source

The use of synchrotron X-ray powder diffraction for the quantitative analysis of very low levels (0.25–3.5wt%) of chrysotile asbestos in bulk samples is examined. A study of chrysotile in a pure alumina matrix indicates that the detection limit is ca. 0.1wt% and the quantification limit ca. 0.2wt%. A second study using a more complex matrix, chrysotile in a gypsumvermiculite mixture, indicates a quantification limit between ca. 0.25 and 0.5wt% for dehydrated samples. The sensitivity of the method can be increased if appropriate chemical pre-treatments using sodium ethylenediamminetetraacetate (EDTA) are performed to remove the gypsum, which is the major component of the mixture. A study of the EDTA treated materials shows no change in the chrysotile and confirms the use of this procedure.