Page:NIOSH Manual of Analytical Methods - 7505.pdf/2

 LEAD SULFIDE: METHOD 7505, Issue 2, dated 15 August 1994 - Page 2 of 7 REAGENTS: 1.

2. 3.

EQUIPMENT:

Lead sulfide, ACS grade, <10-µm particle size.* NOTE: Perform a qualitative analysis (step 10) to determine the purity of the lead sulfide. The material also must be ultrasonically wet-sieved with a 10-µm pore size sieve to approximate respirable dust. Evaporate the alcohol. Dry the sieved material in an oven at 110 °C for 1 h, cool and store in a desiccator. 2-Propanol. Tetrahydrofuran (THF).*



See SPECIAL PRECAUTIONS.

1. Sampler: a. Filter: 37-mm diameter, 5.0-µm pore size, polyvinyl chloride filter supported with backup pad in a two-piece, 37-mm cassette filter holder (preferably, conductive) held together by tape or cellulose shrink band. b. Cyclone: 10-mm nylon, Higgins-Dewell (HD), or equivalent. c. Sampling head holder: Holder must keep the cassette, cyclone and coupler together rigidly so that air enters only at the cyclone inlet. 2. Bulk sampler: PVC membrane filter, 37-mm, 5-µm pore size in two-piece filter cassette. Sample closed face at 2 L/min. 3. Sampling pumps: HD cyclone, 2.2 L/min; nylon cyclone, 1.7 L/min; and bulk sampler, 3 L/min. 4. Silver membrane filters, 25-mm diameter, 0.45-µm pore size (Selas Flotronics, Millipore Corp., or equivalent). 5. X-ray powder diffractometer equipped with copper target X-ray tube, graphite monochromator and scintillation detector. 6. Reference specimen (mica, Arkansas stone or other stable standard) for data normalization. 7. Filtration apparatus and side arm vacuum flask with 25- and 37-µm filter holders. 8. Sieve, 10-µm, for wet sieving. 9. Analytical balance (0.01 mg); magnetic stirrer; ultrasonic bath or probe; volumetric pipettes and flasks; centrifuge tubes (wide mouth), 40-mL, and test tube rack; desiccator; reagent bottles, 1-L, with ground glass stoppers; drying oven; polyethylene wash bottle; Pyrex beakers, 50-mL, and matching watchglasses; and glue or tape for securing Ag filters to XRD holder.

SPECIAL PRECAUTIONS: THF is extremely flammable and should be used in a fume hood. Avoid inhaling lead sulfide dust [3]. SAMPLING: 1. 2.

Calibrate each personal sampling pump with a representative sampler in line. Sample at 1.7 ± 5% L/min with a nylon cyclone or 2.2 L/min with an HD cyclone for a total sample size of 600 to 1000 L. Do not exceed 2 mg dust loading on the filter. NOTE: Do not allow the sampler assembly to be inverted at any time. Turning the cyclone to anything more than a horizontal orientation may deposit oversized material from the cyclone body onto the filter. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94