HYDRAZINE: METHOD 3503, Issue 2, dated 15 August 1994 - Page 3 of 3 b. c. d.
Process the working standards according to steps 7 through 10. Determine absorbance for each solution (steps 13 and 14). Prepare calibration graph (absorbance vs. µg hydrazine).
MEASUREMENT: 13. 14.
Set up the spectrophotometer according to manufacturer's instructions. Place blank solution (from step 12.a) into reference cuvette. Determine absorbance of solution at 480 nm.
CALCULATIONS: 15. 16.
Determine the quantities of hydrazine in the sample, W (µg), and average media blank, B (µg), from the calibration graph. Calculate the concentration, C (mg/m 3), of hydrazine in the air volume sampled, V (L):
EVALUATION OF METHOD: This method is based on Method S237 using 15 mL of 0.1 M HCl for sampling instead of 10 mL. Method S237 was validated with controlled atmospheres of hydrazine [1]. Overall precision ( SˆrT) was 0.094 (18 samples, pooled) for 91-L samples at 0.59 to 3.4 mg/m 3. Concentrations of hydrazine in controlled atmospheres were not verified by an independent method. Average collection efficiency at 0.9 L/min for six bubblers was 0.997 at 3.4 mg/m 3. Average recoveries from HCl solution were 1.03, 0.98 and 1.01 at the 60.7-, 121- and 243-µg levels of hydrazine, respectively. The Sr for analysis = 0.031 (18 samples, pooled). Samples at the 121-µg level were stable during storage in 0.1 M HCl for six days at room temperature.
REFERENCES: [1] Documentation of the NIOSH Validation Tests, S237, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-185 (1977). [2] NIOSH Manual of Analytical Methods, 2nd. ed., V. 3, S237, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-157-C (1977). [3] Ibid. V. 1, P&CAM 248, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-157-A (1977). [4] Ibid. S143, S149, S160. [5] Criteria for a Recommended Standard...Occupational Exposure to Hydrazine, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 78-172 (1978). [6] Dambrauskas, T., and H. H. Cornish. Am. Ind. Hyg. Assoc. J., 23, 151-156 (1962).
METHOD REVISED BY: Samuel P. Tucker, Ph.D., NIOSH/DPSE; S237 developed under NIOSH Contract CDC-99-74-45.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
