Page:NIOSH Manual of Analytical Methods - 5004.pdf/3

 HYDROQUINONE: METHOD 5004, Issue 2, dated 15 August 1994 - Page 3 of 3 MEASUREMENT: 9. 10.

Set HPLC to conditions given on page 5004-1. Inject 100-mL sample aliquot. Measure peak area. Retention time is ca. 5.2 min under these conditions.

CALCULATIONS: 11. 12.

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

EVALUATION OF METHOD: Method S57 [2] was issued on November 26, 1976, and validated over the range 0.8 to 4 mg/m 3 at 20 °C and 762 mm Hg using 90-L air samples [1,5]. Overall precision, SˆrT, was 0.061 with average recovery 105%, representing a non-significant bias. The atmospheres were generated by atomization of an aqueous solution of hydroquinone into dry air; aerosol concentrations were independently verified by direct UV spectrophotometry on filter samples. Average collection efficiency was 100% at 4 mg/m 3. No loss of hydroquinone was seen from filters spiked with 720 µg hydroquinone, and then used to sample 180 L clean air, indicating the hydroquinone vapor pressure is not significant at these conditions. At elevated temperature, however, contribution from vapor may be significant. Storage studies were conducted by storing exposed filters in 1% acetic acid at ambient temperature for seven days. No change in hydroquinone concentration was seen.

REFERENCES: [1] Backup Data Report No. S57, NIOSH Contract 210-76-0123 (unpublished, 1976), available as "Ten NIOSH Analytical Methods, Set 2," Order No. PB 271-464, from NTIS, Springfield, VA 22161. [2] NIOSH Manual of Analytical Methods, 2nd ed., V. 2, S57, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-157-B (1977). [3] User check, A. D. Little, Inc., NIOSH Sequence #4121Q (unpublished, October 25, 1983). [4] Criteria For A Recommended Standard-Occupational Exposure to Hydroquinone, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 78-155 (1978). [5] NIOSH Research Report-Development and Validation of Methods for Sampling and Analysis of Workplace Toxic Substances, U.S. Department of Health and Human Services, Publ. (NIOSH) 80-133 (1980).

METHOD REVISED BY: Jerome Smith, Ph.D., NIOSH/DPSE; S57 originally validated under NIOSH Contract 210-76-0123.

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