Page:NIOSH Manual of Analytical Methods - 7603.pdf/3

 QUARTZ in coal mine dust: METHOD 7603, Issue 3, dated 15 March 2003 - Page 3 of 7 EQ UIPM ENT : - cont. and stirring bars. 15. Reagent bottles with ground glass stoppers, 500-m L, and vo lum etric flasks, 500-m L.** 16. Tweezers. 17. Petri dishes, plastic, for 47-mm diameter filters. 18. Polyethylene wash bottles; metal spatulas. 19. Serological pipets, various sizes as required. 20. Lighted viewing box (optional).

Glassware should be detergent-washed, rinsed thoroughly with distilled or deionized water, and then with 2-propanol, and dried in a dust-free area.

SPECIAL PRECAUTIONS: Avoid inhaling quartz dust [6]. 2-Propanol is flam m able. H ydrochloric acid is corrosive and should be handled in a fume hood. SAMPLING: 1. Calibrate each personal sampling pump with a representative sampler in line. 2. Preweigh each filter to the nearest 0.01 mg. 3. Sa m ple at 1.7 ± 5% L/min with nylon cyclone or 2.2 ± 5% L/m in with HD cyclone fo r a tota l sam ple volum e of 300 to 1000 L. Do not exce ed 2 m g dust loading on the filter. NOT E 1: Do not allow the sampler assembly to be inverted at any time whe n using a cyclone. Turning the cyclone to anything other than a horizontal orientation may deposit oversized m aterial from the cyclone body onto the filter. NOT E 2: A single sampler/flow rate s ho uld be used for a given application. Sampling for both crystalline silica and coal mine dust should be done in accordance with the ISO/CEN/ACGIH/ASTM respirable aerosol sampling convention. Flow rates of 1 .7 L/m in for the Dorr-Oliver nylon cyclone and 2.2 L/min for the Higgins-Dewell cyclone have been found optim al for this purpose. Outside of coal m ine dust sam pling, the regulatory agencies currently use these flow rates with the Do rr-Oliver cyclone in the United States and the Higgins-Dewell sampler in the United Kingdom. Though the sampling recomm endations presented in a NIOSH Criteria Document have been formally accepted by MSHA for coal mine dust sampling, the Dorr-Oliver cyclone at 2.0 L/min with 1.38 conversion factor is currently used in the United States for the purpose of matching an earlier sampling con vention [7]. In any case, a single sam pler/flo w rate should be used in any given application so as to eliminate bias introduced by differences between sampler types and sam pler convention s [3].

SAMPLE PREPARATION: 4. 5.

Reweigh the filters under conditions identical to those before preweighing. The difference is the sam ple weight, W s (µg). Ash sample and blank filters by one of the following methods: a. Low-temperature ashing. Using forceps, trans fer filter to a 50-mL beaker. Ash 2 h at 300 watts RF power and oxygen flow rate of 75 m L/m in fo llowing tec hniques rec om m ended in the instrument m anual. After ashing, add 15 m L 2-propan ol to each beak er. b. Muffle furnace ashing. (1) If the samples contain calcite in concentrations greater than 20% of the total dust loading, wash the filters with acid using the filtration apparatus with the 1.6-cm ID glass fun nel. Place a 25-m m glas s fibe r filter over the frit area, then place a 0.5-µm, 37-mm PVC filter NIOSH Manual of Analytical Methods (NMAM), Fourth Edition