Page:NIOSH Manual of Analytical Methods - 5508.pdf/3

 KEPONE: METHOD 5508, Issue 2, dated 15 August 1994 - Page 3 of 4

11.

12.

c. Analyze together with samples and blanks (steps 13 through 15). d. Prepare a calibration graph of peak area or peak height vs. ng of Kepone per sample. Determine the average recovery (R) of Kepone from filters. a. Fortify six filters with about 7 µL of 50 µg/mL calibration stock solution. b. Allow the filters to air dry. c. Prepare samples according to steps 5 through 7. d. Analyze samples with standards according to steps 13 through 15. e. Calculate the average recovery, R (mass of Kepone found divided by mass of Kepone applied). Determine the average recovery of Kepone from impingers. a. Fortify each of six impingers containing 15 mL 0.1 M NaOH solution with 100 µL 1-µg/mL impinger recovery stock solution. b. Prepare samples according to steps 8 and 9. c. Analyze samples with standards according to steps 13 through 15. d. Calculate the average recovery.

MEASUREMENT: 13. 14.

15.

Set the gas chromatograph to conditions given on page 5508-1. t r of Kepone = 4.6 min, and t r of Mirex = 9.2 min for these conditions. Inject 5-µL aliquots of sample solutions and standards using solvent-flush technique. NOTE: Rinse the syringe thoroughly after each injection with methanol and then with benzene, otherwise traces of Kepone will remain in the syringe. Measure peak area or peak height.

CALCULATIONS: 16.

17.

Determine the quantities in ng of Kepone (corrected for R) on the filter (W f), in the impinger (W i), in the average filter blank (B f), and in the average impinger blank (B i) from calibration graphs based on standards analyzed with the samples. Calculate the concentration, C (µg/m 3), of Kepone in the air volume sampled, V (L):

EVALUATION OF METHOD: This method was tested with fortified filters, fortified NaOH solutions and controlled atmospheres near 25 °C. The overall precision including pump error was 0.234 [1]. The relative standard deviation ( Sr) for filters was 0.228 (10 samples, pooled) for 376-L samples at 2.5 and 2.6 µg/m 3. Quantities of Kepone found in impingers were less than 50 ng. The quantity of Kepone found in each impinger corresponded to about 0.1 ng or less for each liter of air in a sample. Collection efficiencies of impingers were roughly 50%. Average recovery of 360 ng of Kepone from filters was 0.89; Sr was 0.014 for six samples. Kepone was stable on filters at room temperature for 12 days. Average recovery of 45 ng Kepone from 45-mL aliquots of 0.1 M NaOH solution was 1.01; Sr was 0.060 for 8 samples. Average recovery of 79 ng Kepone from 10-mL aliquots of 0.1 M NaOH solution was 1.13 after 14 days of storage at room temperature. Personal and area samples (45 to 84 L) were collected by this method at a Mirex formulation plant. Mirex was found on filters in quantities of 240 to 1240 µg and in impingers in quantities of 0.3 to 16 µg. Although no Kepone was detected on filters, Kepone in quantities of 0.1 to 2 µg was found in impingers. Most or all of the Kepone in each impinger was produced by chemical conversion of Mirex. The accuracy of this method is greater than ± 45%, greatly exceeding the NIOSH criterion of ± 25%.

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