Quantitative determination of chrysotile asbestos in bulk materials by combined Rietveld and RIR methods

Because. of their potential ,to induce a nurnber of pathoLogical diseases and their widespread industrial usage in the past, the fibrous rninerals, forming, asbestos bave been the subject ofa nurnbsr . of studres in the past. Alrh.o.ugh quantification of asbestos minerals by epticaìend-electron .. microscopy (SEM, TEM) is a routine technique in the case of dispersed airborn fibers, the-detection andthe quantification of .5111a1almount of fibrous minerals Iike chrysotile in bulk materials such as building materrals is exceedingly difficùlt. ,A method for the deiection and .evaluation ef asbestos minerais in massi ve samples is described.ibased on -li combination of Rietveld and R1.R (Reference Intensity Ratio) rnethods. Lowet detection limirs are about 0.5-1.0 wt % (or chrysotile. depending on powder partern, counting statistics, arrd matrix absorption: The chrysotile wt % determined on powder diffraction profìles collsoted on a conventional instrurnent is precise to about LO wt % absolute (relative error 'in the range 0-10%). The technique is .of straightforward application. If compared with the commonly used microscopio or spectrescopic techniques, it is of rnuch advantagé frorn the point ofview of lime, and the results afe more accurate and statistically significant of the bulk material, A mode! for the cylindrically disordered strueture of fibrous chrysotile is especially developed (or the sirnulation of the X-ray powder patterns, and il is proposed bere.