COAL TAR PITCH VOLATILES: METHOD 5023, Issue 2, dated 15 August 1993 - Page 3 of 3 NOTE: An aliquot of the solution may be taken at this step if other analyses (e.g., polynuclear aromatic hydrocarbons) are to be performed on the sample. Apply the appropriate aliquot factor in calculations.
CALIBRATION AND QUALITY CONTROL: 7. 8.
Zero the microbalance on the 1.0 mg range and calibrate per balance manufacturer's directions. NOTE: Perform weighings at constant temperature and relative humidity. Process three blank filters through the extraction and measurement procedures.
MEASUREMENT: 9. 10.
11.
Transfer via pipet a 1.0-mL aliquot of sample extract to a preweighed weighing cup. Place weighing cup in vacuum oven preheated to 40 °C. Apply vacuum until pressure in the oven is 7 to 27 kPa (50 to 200 mm Hg). Allow solvent to evaporate for 2 hrs. Release vacuum by slowly opening release valve which has an in-line filter to remove room dust. Equilibrate the weighing cup to the temperature and relative humidity of the balance room for at least 30 min. Weigh the weighing cup to the nearest microgram.
CALCULATIONS: 12. 13.
Determine the mass of organic-soluble residue found in the sample aliquot, W (µg), and in the average media blank, B (µg), and multiply by 5 to give total sample mass. Calculate concentration, C, of organic-solubles in the air volume sampled, V (L):
EVALUATION OF METHOD: Several benzene extracts of samples of aluminum reduction plant emissions were combined to give a solution containing 1.35 mg of benzene-soluble material per sample; nine aliquots of this solution gave residue weights with a relative standard deviation of 0.02. Benzene extracts of six blank filters gave residue weights with a relative standard deviation of 0.23 [6].
REFERENCES: [1] NIOSH/OSHA Occupational Health Guidelines for Chemical Hazards, Coal Tar Pitch Volatiles, U.S. Department of Health and Human Services, Publ. (NIOSH) 81-123 (1981), available as GPO Stock
- 017-033-00337-8 from Superintendent of Documents, Washington, DC 20402.
[2] Criteria for a Recommended Standard ... Occupational Exposure to Coal Tar Products, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 78-107 (1978). [3] Criteria for a Recommended Standard ... Occupational Exposure to Coke Oven Emissions, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 73-11016 (1973). [4] 1992-1993 Threshold Limit Values and Biological Exposure Indices. American Conference of Governmental Industrial Hygienists, Cincinnati, OH (1992). [5] UBTL Report, NIOSH Sequences #4229-T,U,V (unpublished, April 27, 1984). [6] NIOSH Manual of Analytical Methods, 2nd ed., Vol. 1, P&CAM 217, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-157-A (1977).
METHOD REVISED BY: B. R. Belinky, NIOSH/DPSE. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/93
