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 2,4,7-TRINITROFLUOREN-9-ONE: METHOD 5018, Issue 2, dated 15 August 1994 - Page 3 of 3 11.

12.

Determine recovery (R) over the calibration range (step 10) at least once for each lot of filters used for sampling. Prepare three filters at each of five levels plus three blanks. a. Add a known amount of TNF in toluene to media blank filters. Allow to dry. b. Place filters in test tubes and allow to stand overnight. c. Extract filters (steps 5 through 9) and analyze together with working standards (steps 13 through 15). d. Prepare a graph of R (mass recovered/mass added) vs. µg TNF recovered. Analyze three quality control blind spikes and three analyst spikes to ensure that calibration graph and recovery graph are in control.

MEASUREMENT: 13. 14. 15.

Set up the liquid chromatograph according to manufacturer's recommendations and to the conditions given on page 5018-1. Inject sample aliquot using syringe, fixed volume sample loop or autosampler. Measure peak area. NOTE: If peak area is above the range of the standards, dilute with toluene, reanalyze, and apply the appropriate dilution factor in calculations.

CALCULATIONS: 16. 17.

Determine the mass, µg (corrected for R) of TNF found in the sample (W) and in average media blank (B). Calculate concentration, C, of TNF in the air volume sampled, V (L):

EVALUATION OF METHOD: Lab-tested with 2,4,7-trinitrofluoren-9-one spiked filters. The average recovery was 95% over the range 0.2 to 4.0 µg per sample and had a pooled precision ( Sr) of 0.056. PTFE filters with a loading of 0.4 µg were stored for two weeks at room temperature with no loss of analyte [1,2].

REFERENCES: [1] [2]

NIOSH Manual of Analytical Methods, 2nd ed., Vol. 7, P&CAM 348, U.S. Department of Health and Human Services, Publ. (NIOSH) 82-100 (1981). Seymour, M. J. J. Chrom., 236, 530-534 (1982).

METHOD WRITTEN BY: Martha J. Seymour, NIOSH/DPSE.

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