Page:NIOSH Manual of Analytical Methods - 5800.pdf/3

 POLYCYCLIC AROMATIC COMPOUNDS, TOTAL: METHOD 5800, Issue 1, dated 15 January 1998 - Page 3 of 5

4.

Refrigerate samples upon receipt at the laboratory at 4 C.

SAMPLE PREPARATION:

5. 6.

7.

8.

NOTE: Some applications of the data need only total PACs per sample rather than total PACs per individual medium. In these cases, thefilters and sorbent section may be combined into the same screw-capped test tube as a single sample. Remove the samples from the refrigerator and allow to equilibrate to ambient temperature. Extract filters. a. Transfer the filter using forceps to a 16 x 100 mm screw capped test tube. b. Add 4 mL of hexane. c. Rotate the sample for at least 12 hours using a 360 rotator. NOTE: Minimize exposure to light during extraction step. Extract solid sorbent tubes. a. Transfer front glass wool plug and front sorbent section to a 16 x 100 screw-capped test tube. b. Transfer the back sorbent section and remaining glass wool plugs to a separate screw-capped test tube. c. Add 4 mL of hexane to each sample. d. Rotate the sample for at least 12 hours using a 360 rotator. NOTE: Minimize exposure to light during extraction step. Solid phase extraction: a. Condition a cyano solid phase extraction column by washing in sequence with 3-mL aliquots of methanol, methylene chloride, and hexane at a flowrate of approximately 0.25 mL/sec. b. Transfer 2 mL of the extracted sample in hexane to the head of the cyano-SPE column. c. Elute at approximately 0.15 mL/sec and collect in a separate 16 x 100 mm screw capped test tube. d. Add 2 mL of hexane and elute through the column at approximately 0.15 mL/sec and combine with the first hexane eluate. e. Add 4 mL of DMSO to the hexane eluates, cap, and rotate for at least 12 hours. f. Using a Pasteur pipette, transfer an aliquot of the DMSO layer (bottom) to an autosampler vial.

CALIBRATION AND QUALITY CONTROL: NOTE: This method uses a mixture of 16 PACs as the standard calibration solution to mimic the field samples. The commercial standard chosen was Supelco QTM Test Mixture that contains 2000 µg/mL for each of 16 PACs or 32000 µg/mL total PAC. 9.

Calibrate daily with at least six working standards over the range of interest. a. Dilute aliquots of calibration stock solution (QTM Test Mixture) with DMSO. b. Analyze working standards and blanks (Steps 12 through 15). Intersperse standards among the samples. c. Prepare 2 calibration graphs (one for each detector) in terms of mass of total PACs. (Fluorescent peak area vs. µg of total PAC per sample). 10. Determine recovery (R) from filters and desorption efficiency (DE) from sorbent tubes (Steps 5 through 8) in the range of interest (Step 9) at least once for each lot of filters and sorbent tubes used for sampling. a. Prepare spiking solutions by making dilutions of the Supelco QTM Test Mixture with hexane. b. Using a microliter syringe, spike three filters and three solid sorbent tubes at five concentration levels with the QTM Test mixture. Allow the media to dry in the dark overnight. c. Analyze the filters and sorbent tubes (Steps 12 through 15). Prepare graphs of R or DE vs. µg recovered. 11. Analyze three quality control blind spikes and three analyst spikes to ensure that the calibration, recovery (R), and desorption efficiency (DE) graphs are in control.

MEASUREMENT: 12. Set solvent delivery system to pump 1.5 mL/min of acetonitrile through the system. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition