Direct Quantative Determination of Silica by X-ray Diffraction on Pvc Membrane Filters

Abstract

Exposure of industrial workers to respirable crystalline silica is receiving considerable attention at present from industrial laboratories and regulatory agencies. Analytical methodology for rapid and accurate determinations of microgram quantities of silica is necessary. The X-ray diffraction method which has been recommended by NIOSH requires lengthy sample preparation.An X-ray diffraction method has been developed for the quantitative analysis of α-quartz directly on polyvinyl chloride filters in the microgram range. The minimum detectable concentration of α-quartz is approximately 2μg/cm2. This represents a sensitivity comparable to that claimed using the Bumsted method. The necessity of ashing the filter and depositing the residue on silver membrane filters, as well as the addition of a standard, is avoided. This minimizes handling and alteration of the sample.