1 Scope
This document is a standard for the analysis by Fourier-Transform Infrared (FTIR) of respirable crystalline silica (RCS) in samples of air collected on collection substrates (i.e. filters or foams). Three analytical approaches are described for whom the dust from the sample collection substrate is
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a) analysed directly on sampled filter,
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b) recovered, treated and deposited onto another filter for analysis, or
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c) recovered, treated and pressed into a potassium bromide (KBr) pellet for analysis.
This document provides information on the instrumental parameters, the sensitivity of different sampling apparatus, the use of different filters and sample treatment to remove interference. In this document the expression RCS includes the most common polymorphs quartz and cristobalite.
This document excludes the less common polymorphs of crystalline silica, such as tridymite.
Under certain circumstances (i.e. low filter dust loads, low silica content), the analytical approach described in this method cannot fulfil the expanded uncertainty requirements of ISO 20581. Guidance for calculation of uncertainty for measurements of RCS is given in ISO 24095.