Physicochemical characterization of cryogenically ground, size separated, fibrogenic particles

A method for cryogenically grinding and separating (by size) fibrogenic minerals in the 1-micron size range is described and verified for chrysotile asbestos, quartz, forsterite (an olivine), and tantalum with a battery of analytical tests. Through use of energy dispersive X-ray spectroscopy, neutron activation analysis, X-ray photoelectron spectroscopy, and X-ray diffraction analysis it is shown that the grinding and separation procedure described does not alter the mineral composition, preserves the trace element composition, maintains the surface composition, and preserves the crystalline structure. Further, investigation of electrokinetic properties of these dusts by electrophoretic quasielastic light scattering is described. The small size dispersity of these samples facilitates use of this technique for the determination of the apparent electrokinetic charge and estimations of surface charge density at ionic strengths below physiological. It is suggested that analyses of the type described here be an integral part of studies of the fibrogenic, immunologic, or toxicologic properties of such minerals. This work has been performed in conjunction with the authors' studies of the effects of these particulates on macrophage ultrastructure and immunologic function in vitro.