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BENZOYL PEROXIDE: METHOD 5009, Issue 2, dated 15 August 1994 - Page 3 of 3 calibration graph and recovery graph are in control. MEASUREMENT: 10. 11. 12.

Set high performance liquid chromatograph according to manufacturer's recommendations and to conditions given on page 5009-1. Flush sample loop thoroughly with sample (0.1 mL) and inject sample. Measure peak area.

CALCULATIONS:

13. 14.

Read mass, mg (corrected for recovery), of benzoyl peroxide found on sample filters, W (mg), and on average blank filters, B (mg), from calibration graph. Calculate concentration, C (mg/m 3), of benzoyl peroxide in the air volume sampled, V (L):

EVALUATION OF METHOD: Method S253 was issued on January 21, 1977 [3], and validated over the range 3.1 to 19.1 mg/m 3 at 26 °C and 764 mm Hg, using 90-L samples [1,5]. The collection efficiency of the filter was determined to be 1.00, since no benzoyl peroxide was detected on a backup filter mounted directly behind the front filter. Storage stability studies on the filters held in the filter cassettes indicated a 9.3% decrease in the amount of benzoyl peroxide recovered after one week. Benzoyl peroxide was stable in ethyl ether at room temperature for at least one week. Overall precision, SˆrT, was 0.060. Recovery was 0.97 in the range 0.225 to 0.900 mg per sample for 18 spiked samples.

REFERENCES: [1] NIOSH Backup Data Report, S253, for Benzoyl Peroxide, prepared under NIOSH Contract No. 210-76-0123, available as "Ten NIOSH Analytical Methods, Set 2," Order No. PB 271-464, from NTIS, Springfield, VA 22161. [2] UBTL Memorandum, UBTL Analytical Laboratory Report for Benzoyl Peroxide, Sequence #2182-J (unpublished, February 29, 1980). [3] NIOSH Manual of Analytical Methods, 2nd. ed., V. 4, S253, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 78-175 (1978). [4] Criteria for a Recommended Standard...Occupational Exposure to Benzoyl Peroxide, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-166 (1977). [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: R. Alan Lunsford, Ph.D., NIOSH/DPSE; S253 originally validated under NIOSH Contract 210-76-0123.

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