ETHYLENE THIOUREA: METHOD 5011, Issue 2, dated 15 August 1994 - Page 4 of 4 13.
Calculate the concentration of ETU, C (mg/m 3), in the air volume sampled, V (L):
EVALUATION OF METHOD: The method was tested with 21 PVC (VM-1)/ETU spiked samples in the range 15 to 150 µg per sample with an average recovery of 98.0 ± 3.2% [1]. It was also tested with 20 mixed cellulose ester filters spiked with ETU in the range of 15 to 150 µg per sample, giving an average recovery of 99.2% ± 3.6% [1]. All calibration graphs indicated a minimum linear correlation coefficient of 0.9999 [1]. The method was also used on 50 field samples on VM-1 filters in two surveys [1]. The amounts of ETU found ranged from 5 to 56 µg per sample. Storage stability was not determined, nor was overall method bias determined.
REFERENCES: [1] [2] [3] [4]
Palassis, J. Sampling and Analytical Determination of Airborne Tetramethyl and Ethylene Thiourea, Am. Ind. Hyg. Assoc. J., 41, 91-97 (1980). NIOSH Manual of Analytical Methods, 2nd. ed., V. 4, P&CAM 281, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 78-175 (1978). Special Occupational Hazard Review...Ethylene Thiourea, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 79-109 (1978). NIOSH Current Intelligence Bulletin No. 22: Ethylene Thiourea, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 78-144 (1978).
METHOD WRITTEN BY: John Palassis, NIOSH/DTMD.
APPENDIX: 1.
PREPARATION OF COMPLEXING REAGENT a. Weigh 0.500 g Na 2Fe(CN) 5NO·2H 2O in a 50-mL beaker. Dissolve in 10 mL distilled water. b. Grind together 0.500 g NH 2OH·HCl and 1.00 g NaHCO 3 in a mortar. c. In a hood, add the ground mixture to the solution from (a.). When bubbling ceases, add 0.10 mL bromine. When reaction stops, add ca. 10 mL distilled water. Filter. Rinse beaker with 4 mL distilled water and filter. Transfer filtrate to a 25-mL volumetric flask and dilute with distilled water to the mark. Refrigerate. Stable at least two weeks at 4 °C [3].
2. PURIFICATION OF ETU a. In a 250-mL Erlenmeyer flask, weigh 3 to 5 g ETU. Dissolve in 100 mL 1:1 methanol:water. Heat to boiling in a hood. Cool 5 min at room temperature. Add 5 mL hexane. Shake 30 sec. Cover with watchglass. Let stand 1 h at room temperature. Filter the ETU crystals, and wash with 100 mL 1:1 methanol:water. Let the crystals air dry in a hood.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
