Page:NIOSH Manual of Analytical Methods - 2515.pdf/4

 DIAZOMETHANE: METHOD 2515, Issue 2, dated 15 August 1994 - Page 4 of 4 EVALUATION OF METHOD: Method S137 was issued on June 6, 1975 [2]. The precision and bias were determined by analyzing generated atmospheres of diazomethane containing 0.17, 0.36 and 0.8 mg/m 3 at 26 °C and 765 mm Hg using 10-L samples [1]. The recovery (concentration found in air divided by concentration determined by an independent method involving collection in solutions of benzoic acid in xylene) was found to decrease with concentration according to the equation in step 15. Recoveries were 0.68 to 0.93 for six pairs of data in the apparent concentration range 0.12 to 7 mg/m 3. Sample stability was not determined. The method does not meet the 10% bias criterion for a valid NIOSH method. Breakthrough of the front section of the coated XAD-2 tube was not observed after sampling 53 L of dry test atmosphere containing 0.83 mg/m 3 for 240 min at 0.22 L/min. Desorption efficiencies for samples spiked with methyl octanoate were 1.01 to 1.05. The collection efficiency and reaction of diazomethane with the octanoic acid-coated resin may be strongly dependent on sample flow rates; therefore, all samples must be collected at a flow rate of 0.2 L/min only.

REFERENCES: [1] Documentation of the NIOSH Validation Tests, S137, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-185 (1977), available as GPO Stock #017-033-00231-2 from Superintendent of Documents, Washington, DC 20402. [2] NIOSH Manual of Analytical Methods, 2nd ed., Vol. 3, S137, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-157-B (1977). [3] NIOSH/OSHA Occupational Health Guidelines for Chemical Hazards, U.S. Department of Health and Human Services, Publ. (NIOSH) 81-123 (1981), available as GPO Stock #017-033-00337-8 from Superintendent of Documents, Washington, DC 20402. [4] Merck Index, 10th ed., Merck & Co., Inc., NJ (1983).

METHOD REVISED BY: Julie R. Okenfuss, NIOSH/DPSE; S137 originally evaluated under NIOSH Contract CDC-99-74-45.

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