OSHA 142 – Product & Materials Guide

Quartz and Cristobalite Concentration by XRD

OSHA 142 is an analytical method used to determine respirable crystalline silica (RCS) exposure in the workplace. Respirable crystalline silica refers to crystalline silica particles with a diameter of <10 μm. Similar to NIOSH Method 7500, OSHA 142 can distinguish concentrations of all three polymorphs of crystalline silica (i.e., quartz, cristobalite, tridymite) within collected samples. While quartz is the most common polymorph, newly published exposure limits from OSHA and the EU are based upon all three polymorphic forms.

Samples for OSHA 142 testing samples are collected using a 37 mm, 5.0 μm PVC membrane in a two-piece cassette filter holder, a 10 mm cyclone, and a personal sampling pump. Placing a cyclone between the cassette and sampling pump when sampling at the recommended rate prevents non-respirable particles (>10 μm) from being collected in the cassette. After collection, samples are processed and transferred to a 0.45 um silver membrane for diffraction analysis via XRD. Prior to sample analysis, calibration curves are generated with quartz, cristobalite, and tridymite standards of varying concentrations.

Analytical Method: XRD (x-ray diffraction)

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Materials needed for OSHA 142

• Empty 37 mm air monitoring cassette
• 5 μm, 37 mm PVC membrane filter
• 0.45 μm, 25 mm silver membrane
• 6-place, stainless-steel membrane holder manifold
• 25 mm glass microanalysis membrane holders
• Glass funnels with matching fritted-glass bases
• Forceps to handle filter membrane

Products for OSHA 142

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