Page:NIOSH Manual of Analytical Methods - 5042.pdf/4

 BENZENE-SOLUBLE & TOTAL PARTICULATE (ASPHALT FUME): METHOD 5042, Issue 1, dated 15 January 1998 - Page 4 of 7

1. Number the backup pads with a ballpoint pen and place them, numbered side down, in the filter cassette bottom sections. 2. Preweigh the filters by the weighing procedure given in step 3. Record the mean tare weight of sample filters, W1 and field blanks, B1 (µg). 3. Weighing procedure: a. Equilibrate the filters or weighing cups in an environmentally controlled weighing area or chamber for at least two hours. b. Zero the balance before each weighing. c. Using forceps, pass each filter or weighing cup over a static neutralizer. Repeat this step if the filter or weighing cup does not release easily from the forceps or attracts the balance pan. Static electricity can cause erroneous weight readings. d. Weigh each filter or weighing cup until a constant weight is obtained (two successive weighings within 10 µg). Record the mean of the last two weighings to the nearest microgram. 4. Assemble the filter in the filter cassette and close firmly to prevent leakage. Place a plug in each opening of the filter cassette. Place a cellulose shrink band around the filter cassette, allow to dry and mark with the same number as the backup pad.

SAMPLING: 5. Calibrate each personal sampling pump with a representative sampler in line. 6. Sample at an accurately known flow rate between 1 to 4 L/min for a total sample volume of 28 L to 400 L. Do not exceed a total filter loading of approximately 2 mg total particulate. 7. Collect five field blanks for each day of samplingfor determining the limit of detection (LOD) and the limit of quantitation (LOQ). 8. Replace plugs in cassettes and pack securely for shipment to the laboratory. Recommend samples be refrigerated upon receipt at the laboratory.

CALIBRATION AND QUALITY CONTROL: 9. Use the same balance, if practical, for weighing filters and weighing cups before and after sample collection or benzene evaporation. Check and maintain calibration of balance according to manufacturer’s recommendations. Zero the balance before each weighing. 10. Process three tared media blanks through the measurement procedures for total particulate and benzene-soluble fraction.

TOTAL PARTICULATE MEASUREMENT: 11. After sampling: a. Allow refrigerated sample cassettes to come to room temperature before proceeding. b. Wipe dust from the external surface of the filter cassette with a moist paper towel to minimize contamination. Discard the paper towel. c. Remove the top and bottom plugs from the filter cassette. Equilibrate sampler for at least two hours in the balance room or environmental chamber. d. Remove the shrink band, pry open the cassette, and gently remove the filter to avoid loss of sample. e. Reweigh (step 3) each filter, including field blanks. Record the mean post-sampling weight, 2Wor B2 (µg). Also, record anything remarkable about a filter (e.g., overload, leakage, wet, torn, etc.) f. After weighing, transfer the filter carefully with forceps to a clean test tube and cap the tube.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition