AZELAIC ACID: METHOD 5019, Issue 2, dated 15 August 1994 - Page 3 of 3 c. d.
11.
Analyze together with samples and blanks (steps 12 and 13). Prepare calibration graph (peak area vs. mg azelaic acid). NOTE: If azelaic acid is not 100% pure, correct the mass of azelaic acid standards before preparation of calibration graph. Determine the recovery of azelaic acid from PVC filters at least once for each lot of filters used. a. Weigh various amounts of azelaic acid to cover the range of interest onto PVC filters in marked vials. b. Treat as in steps 5 through 9 and 12 and 13.
MEASUREMENT: 12. 13.
Set gas chromatograph according to manufacturer's recommendations and to conditions given on page 5019-1. Inject a 1-µL sample. Measure peak area after each injection. Calculate the mean area. NOTE: Remove daily the white flakes which accumulate on the FID.
CALCULATIONS: 14. 15.
Determine the mass, mg, of azelaic acid (W) per filter and the average media blank (B) from the calibration graph. Calculate the concentration, C, of azelaic acid in the air volume sampled, V (L):
EVALUATION OF METHOD: The measurement precision, Sr, of this method was determined to be 0.02 using standards in the range 1 to 10 mg per sample. The average recovery of azelaic acid from spiked PVC filters in the range 2 to 10 mg per filter was 94.9 ± 4.3% [1].
REFERENCES: [1] Palassis, J. The Sampling and Determination of Azelaic Acid in Air, Am. Ind. Hyg. Assoc. J., 39, 731-736 (1978). [2] NIOSH Manual of Analytical Methods, 2nd. ed., V. 1, P&CAM 256, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-157-A (1977). [3] NIOSH/OSHA Occupational Health Guidelines for Chemical Hazards, USDHHS Publ. (NIOSH) 81123 (1981).
METHOD REVISED BY: John Palassis, NIOSH/DTMD.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
