Document QggnvK53kx9qYp8vKXR0BDV27

7T * ---- H . . _ . * . . . n. . . I t INTf.lCI'IPAN'f AND INTCK-OEPATiTMENImL COI AESPONOENCc To: Date : Kr. A.7. E`;ar, Foseco Inc.. U.S.A, 1st September, 1972. Na** Oestrlmtnl Ce**ptnr From: D.G. Braddy, Division: Our R-< DG3/M* Ycur Ref.: Copie. tn : (>< aoi* iuii) Mr. M.J. Meilodc; Kr. V. Mexlovs. File. Analysis of Asbestos - Containing Dusts. In my opinion, X-Ray diffraction techniques would be the most suitable for the quantitative determination of asbestos fibres in the presence of other fibres such as slag wool and also, I presume, other particles such as silica, iron oxide etc. At present, ve do not have a' method available which can be applied directly to this specific problem. However, it should ( not prove impossible (in theory, at least) to extend tnc technique which vc axroady use for the quantitative determination of silica (cuartr.) in foundry and steelworks dusts. Tnc asbestos patterns arc much more comnlicated than that of quartz end also give less | sire.-,, linos. For vhi' re*son, I think that vorievs problems right urisc oeforc a satisfactory procedure could be developed, but there is r.o obvious reason way this technique could not be ' rode to work. The percentages of chrysotilc and amositc asbestos i could be determined separately, as their diffraction patterns * arc ouite dissiiiiltr. The other fibres which you mention are j normally completely amorphous and thus do not give X-Ray patterns. ; Analysis of dust is frequently carried out by collecting the sample on a suitable membrane filter and then counting the j number of particles in the deposit under the microscope. For tne i following reasons, I do not tiunk that this would prove suitable l for the current problem. 1 (a) The asbestos fibres could only be distinguished from j the other fibres by means of different shape, diameter etc., , which might well be extremely difficult. (b) Ary microscope technique for particle counting is extremely tedious and tiring to the coerutor, if a sufficiently large number of particles are to be examined in order to obtain a reasonably accurate result. ii*G* l) 1251