Page:NIOSH Manual of Analytical Methods - 7402.pdf/2

 ASBESTOS by TEM: METHOD 7402, Issue 2, dated 15 August 1994 - Page 2 of 7 REAGENTS: 1.

Acetone. (See SPECIAL PRECAUTIONS.)

EQUIPMENT: 1. Sampler: field monitor, 25-mm, three-piece cassette with ca. 50-mm electrically-conductive extension cowl, cellulose ester membrane filter, 0.45- to 1.2-µm pore size, and backup pad. NOTE 1: Analyze representative filters for fiber background before use. Discard the filter lot if mean count is >5 fibers/100 fields. These are defined as laboratory blanks. NOTE 2: Use an electrically-conductive extension cowl to reduce electrostatic effects on fiber sampling and during sample shipment. Ground the cowl when possible during sampling. NOTE 3: 0.8-µm pore size filters are recommended for personal sampling. 0.45-µm filters are recommended for sampling when performing TEM analysis on the samples because the particles deposit closer to the filter surface. However, the higher pressure drop through these filters normally preclude their use with personal sampling pumps. 2. Personal sampling pump, 0.5 to 16 L/min, with flexible connecting tubing. 3. Microscope, transmission electron, operated at ca. 100 kV, with electron diffraction and energy-dispersive X-ray capabilities, and having a fluorescent screen with inscribed or overlaid calibrated scale (Step 15). NOTE: The scale is most efficient if it consists of a series of lines inscribed on the screen or partial circles every 2 cm distant from the center. 4. Diffraction grating replica with known number of lines/mm. 5. Slides, glass, pre-cleaned, 25- x 75-mm. 6. Knife, surgical steel, curved-blade. 7. Tweezers. 8. Grids, 200-mesh TEM copper, (optional: carbon-coated). 9. Petri dishes, 15-mm depth. The top and bottom of the petri dish must fit snugly together. To assure a tight fit, grind the top and bottom pieces together with an abrasive such as carborundum to produce a ground-glass contact surface. 10. Foam, clean polyurethane, spongy, 12-mm thick. 11. Filters, Whatman No. 1 qualitative paper or equivalent, or lens paper. 12. Vacuum evaporator. 13. Cork borer, (about 8-mm). 14. Pen, waterproof, marking. 15. Reinforcement, page, gummed. 16. Asbestos standard bulk materials for reference; e.g. SRM #1866, available from the National Institute of Standards and Technology. 17. Carbon rods, sharpened to 1 mm x 8 mm. 18. Microscope, light, phase contrast (PCM), with Walton-Beckett graticule (see method 7400). 19. Grounding wire, 22-gauge, multi-strand. 20. Tape, shrink- or adhesive-.

SPECIAL PRECAUTIONS: Acetone is extremely flammable (flash point = 0 °F). Take precautions not to ignite it. Heating of acetone must be done in a fume hood using a flameless, spark-free heat source. Asbestos is a confirmed human carcinogen. Handle only in a well-ventilated fume hood.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94