Method 7501

Silica, Amorphous

This method is specific for amorphous silica in crystalline (e.g., quartz) matrices in the range 1 to 10 mg/m³ for a 200-L air sample. Amorphous silica usually contains some crystalline silica. Samples are collected using a filter or a cyclone and filter and analyzed using X-ray powder diffraction. NOTE: This method makes improvements in sample handling and quality assurance to P&CAM 316, which it replaces.

(NIOSH Issue 2: 15 August 1994)


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Method Data

Hold Times, Preservatives, Preps, Collection, Analytical & Documentation
Holding Time:   Indefinite
Preservatives:   N/A
Required Preps:   37 mm, 5.0 µm PVC filter
Collection Method:   Filter or cyclone and filter, 50-400 L @ 5 mg/m3, variable flow rates
Analytical Methodology:   X-ray Powder Diffraction
Documentation:   7501

Analyte List*

Analyte Formula CAS Number Detection Limit
Amorphous Silica, gel
Amorphous Silica, fumed
Diatomaceous Earth
Silicic Acid

* The analytes and detection limits listed for each method represent the typical detection limits and analytes reported for that particular method. Keep in mind that analyte lists may vary from laboratory to laboratory. Detection limits may also vary from lab to lab and are dependent upon the sample size, matrix, and any interferences that may be present in the sample.