'TABLE 4. INFRARED SAMPLING AND ANALYTICAL METHODS FOR CRYSTALLINE SILICA.'
| NMAM 7602 | NMAM 7603 | MSHA P-7 | MDHS 37 | MDHS 38 | |
| Matrix | coal mine dust | coal mine dust | |||
| Sampler | 10-mm nylon cyclone, 1.7 L/min
Higgins-Dewell cyclone, 2.2 L/min |
10-mm nylon cyclone, 1.7 L/min
Higgins-Dewell cyclone, 2.2 L/min |
10-mm nylon Dorr-Oliver cyclone, 2.0 L/min | Higgins-Dewell cyclone, 1.9 L/min | Higgins-Dewell cyclone, 1.9 L/min |
| Filter | 37-mm 0.8 PVC or 5-µm MCE | 37-mm 0.8 PVC or 5-µm MCE | 37-mm 0.8-µm, 5-µm PVC pre-weighed | 37-mm 0.8-µm, 5-µm PVC | 37-mm 0.8-µm, 5-µm PVC |
| Volume | 400-800 L total dust < 2mg |
300-1000 L total dust < 2mg |
not stated | ≥ 456 L total dust < 1mg |
≥ 456 L total dust < 0.7mg |
| Filter Prep | RF plasma asher or muffle furnace | RF plasma asher or muffle furnace | RF plasma asher | none | muffle furnace |
| Analytical Sample Prep | mix residue with KBr, press 13-mm pellet | redeposit on 0.45-µm acrylic copolymer filter | redeposit on 0.45-µm acrylic copolymer filter | none | mix residue with KBr, press 13-mm pellet |
| Standard | polystyrene film | polystyrene film | polystyrene film | polystyrene film | polystyrene film |
| Calibration | quartz diluted in KBr | suspensions of quartz in 2-propanol | suspensions of quartz in 2-propanol | sampling from a generated atmosphere of standard quartz dust | sampling from a generated atmosphere of standard quartz dust |
| Proficiency Testing | PAT | PAT | PAT | WASP | WASP |
| Range (µg quartz) | 10-160 | 30-250 | 25-250 | 10-1000 | 5-700 |
| LOD (µg quartz) | 5 (estimated) | 10 (estimated) | 10 | varies with particle size | varies with particle size |
| Precision* | CV < 15 % @ 30µg | CV = 9.8 % @ 100 - 500 µg | CV = 5-10 % @ 100 - 500 µg | CV = 5 % @ 50 µg | CV = 5 % @ 50 µg |
* Precision is noted in terms of CV (coefficient of variation) for all methods for convenience of comparison. CV is equivalent to (relative standard deviation). In some methods, precision is noted in terms of (pooled relative standard deviation) which is equivalent to
NMAM=NIOSH Manual of Analytical Methods, MSHA=Mine Safety and Health Administration, MDHS=Methods for Determination of Hazardous Substances, PVC=polyvinyl chloride, MCE=methyl cellulose ester, RF=radio frequency, KBr=potassium bromide, PAT=proficiency analytical testing, WASP=workplace analysis scheme for proficiency, LOD=limit of detection, CV=coefficient of variation.
Infrared Methods. IR methods include NMAM 7602, NMAM 7603, MSHA P-7, MDHS 37 and MDHS 38 [63-67]. Details of these methods are listed in Table 4.
