Page:NIOSH Manual of Analytical Methods - 5506.pdf/3

 POLYNUCLEAR AROMATIC HYDROCARBONS by HPLC: METHOD 5506, Issue 3, dated 15 January 1998 - Page 3 of 9

SAMPLING: 1. Calibrate each personal sampling pump with a representative sampler in line. 2. Take personal samples at 2 L/min for a total sample size of 200 to 1000 L. 3. Immediately after sampling, transfer the filter carefully with forceps to a culture tube. Hold filter at edge to avoid disturbing the collected sample. Cap the tube and wrap in aluminum foil. NOTE: This step is necessary to avoid loss of analytes by sublimation. 4. Cap the sorbent tube and wrap in aluminum foil. 5. Ship to laboratory in insulated container with bagged refrigerant.

SAMPLE PREPARATION:

6. 7.

8.

9.

NOTE: UV light may degrade PAHs; therefore, recommend using yellow, UV-absorbing shields for fluorescent lights or use incandescent lighting. Refrigerate samples upon receipt at laboratory. Extract PAH from filters. a. Add 5.0 mL of acetonitrile to each culture tube containing a filter. Similarly, add 5.0 mL of acetonitrile to each culture tube containing the media and reagent blanks. Cap the tubes. b. Place capped tubes in an ultrasonic bath for 30 to 60 min. Desorb PAH from sorbent. a. Score each sorbent tube with a file in front of the front (larger) sorbent section. Break tube at score line. b. Transfer front glass wool plug and front sorbent section to a culture tube. Transfer back sorbent section, and the middle glass wool plug to a second culture tube. c. Add 5.0 mL acetonitrile to each culture tube. Cap the tubes. d. Place capped tubes in an ultrasonic bath for 30 to 60 min. Filter all sample extracts through an 0.45-µm syringe filter.

CALIBRATION AND QUALITY CONTROL: 10. Calibrate daily with at least six working standards. NOTE: If a benzo[e]pyrene standard is needed, weigh desired amount and add to a known volume of the PAH test mixture. a. Dilute aliquots of thePAH test mixture (containing benzo[e]pyrene if needed) with acetonitrile in 10-mL volumetric flasks. The concentration range should cover most of the PAH concentrations in the samples. b. During analysis, intersperse working standards with samples and blanks. c. Prepare calibration graphs (peak area vs. µg of each PAH per sample). 11. Recovery and desorption efficiency. a. Determine recovery (R) from filters and desorption efficiency (DE) from sorbent tubes at least once for each lot of filters and sorbent tubes used in the range of interest. (1) Filters. Using a microliter syringe or a micropipette, spike four filters at each of five concentration levels with a mixture of the analytes. Allow the filters to dry in the dark overnight. Analyze the filters (steps 7, 9, and 13 through 15). Prepare graphs of R vs. amounts found. (2) Sorbent tubes. Transfer an unused front sorbent section to a culture tube. Prepare a total of 24 culture tubes in order to measure DE at five concentration levels plus blank in quadruplicate. Using a microliter syringe or micropipette, add calibration stock solution directly to sorbent. Cap culture tubes and allow to stand overnight. Desorb and analyze (steps 8, 9, and 13 through 15). Prepare graphs of DE vs. amounts found. b. Check R and DE at two levels for each sample set, in duplicate. Repeat determination of R or DE graphs if checks do not agree to within ±5% of R or DE graph. 12. Analyze at least three field blanks for each sample medium.

MEASUREMENT: NIOSH Manual of Analytical Methods (NMAM), Fourth Edition