Method 7500 is used for the collection and analysis of crystalline silica, SiO2, in its most common forms of quartz, cristobalite and tridymite. The sample is collected using a 10mm cyclone and 5 micron PVC filter. After collection the sample is redposited on a 0.45 micron silver membrane filter and analyzed by X-ray diffraction (XRD).
The working range of the method is 0.025 to 25 mg/m3 for an 800L air sample.
NOTE: This is similar to the method in the Criteria Document and P&CAM 259 which has been collaboratively tested.
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| Hold Times, Preservatives, Preps, Collection, Analytical & Documentation | |
|---|---|
| Holding Time: | None specified in the method. |
| Preservatives: | None specified in the method. |
| Required Preps: | 5 um PVC membrane filter, 37 mm |
| Collection Method: | The method recommends a 1.7 - 2.5 L/min. flow rate and a 400 - 1000L sample collection volume. |
| Analytical Methodology: | XRD |
| Documentation: | 
7500
|
| Analyte | Formula | CAS Number | Detection Limit | |
|---|---|---|---|---|
| Cristobalite | SiO2 |
14464-46-1 |
0.005 |
mg/sample |
| Silica, crystalline | SiO2 |
14808-60-7 |
0.005 |
mg/sample |
| Tridymite | SiO2 |
15468-32-3 |
0.005 |
mg/sample |
* 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.