This method is used for the determination of soluble and insoluble tungsten. The sample is collected on cellulose ester membrane filters, extracted in water @ 25°C (soluble) or 1:1 hydrofluoric acid:nitric acid for six hours at 150 °C, and then analyzed by GC/FID. The working range is 0.25 to 5 mg/m³ (soluble) and 0.6 to 5 mg/m³ for a 400 L air sample. This is an elemental analysis and is not compound specific. For cemented tungsten carbide samples, cobalt can be quantitatively determined from the hydrochloric acid extract used to remove interferences. NOTE: This revises P&CAM 271. Method 7300 (ICP-AES) is an alternate measurement method; however, extraction and ashing procedures in this method must be followed.
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| Hold Times, Preservatives, Preps, Collection, Analytical & Documentation | |
|---|---|
| Holding Time: | Stable for at least 2 weeks. |
| Preservatives: | 25 °C |
| Required Preps: | Cellulose ester membrane filter (0.8µm pore size). |
| Collection Method: | Filter: 200L - 1000L @ 1 to 4 L/min. |
| Analytical Methodology: | GC/FID |
| Documentation: | 
7074
|
| Analyte | Formula | CAS Number | Detection Limit | |
|---|---|---|---|---|
| Tungsten | W |
7440-33-7 |
125 |
µg |
* 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.