Determination of Si in Standard Reference Material SRM 295x Silica-on-Filter

Abstract

Respirable crystalline silica is an occupational hazard whose presence in the workplace is strictly regulated. A new series of Standard Reference Materials (SRMs) is being developed to assure the quality of silica measurements and to provide for accurate instrument calibration. SRMs 295x (the value x will designate a specific level of silica loading), Silica-on-Filter, have been prepared by gravimetric delivery of SRM 1878a Respirable Alpha Quartz onto individual filters. The silica on the filter has been verified indirectly by the measurement of the elemental silicon, taking advantage of the knowledge in the filter preparation. An HF acid digestion method has been developed for sample digestion, and a high-resolution inductively coupled plasma mass spectrometric method for the determination of silicon has been developed and validated.