1,1-DIMETHYLHYDRAZINE
(CH3)2NNH2
MW: 60.10
METHOD: 3515, Issue 1
CAS: 57-14-7
3515
RTECS: MV2450000
EVALUATION: PARTIAL
OSHA : C 0.5 ppm (skin) NIOSH: C 0.06 ppm/120 min; carcinogen ACGIH: C 0.5 ppm (skin); suspected human carcinogen (1 ppm = 2.46 mg/m 3 @ NTP)
PROPERTIES:
Issue 1: 15 August 1994
liquid; MP - 58 °C; BP 63 °C; d 0.80 @ 20 °C; VP 157 mm Hg @ 25 °C; vapor density (air = 1) 2.07; flash point - 15 °C (closed cup); flammable range 2 to 95% v/v in air
SYNONYMS: dimazine; unsym-dimethylhydrazine; N,N-dimethylhydrazine.
SAMPLING SAMPLER:
BUBBLER (0.1 M hydrochloric acid)
MEASUREMENT TECHNIQUE:
VISIBLE SPECTROPHOTOMETRY
ANALYTE:
complex of phosphomolybdic acid and 1,1-dimethyl hydrazine
PROCEDURE:
add phosphomolybdic acid; heat sample solution at 95 °C for 60 min; cool solution under tap water; transfer sample to 1-cm cell; read absorbance at 730 nm
CALIBRATION:
standard solutions of 1,1dimethylhydrazine in 0.1 M hydrochloric acid
RANGE:
2 to 250 µg per sample [1]
FLOW RATE: 0.2 to 1.0 L/min VOL-MIN: -MAX:
2 L @ 0.5 ppm 100 L
SHIPMENT:
remove bubbler stem and rinse with 0.1 M hydrochloric acid; seal bubbles with nonreactive stopper
SAMPLE STABILITY:
at least 5 days @ 25 °C
BLANKS:
2 to 10 field blanks per set ESTIMATED LOD: 1 µg per sample [2] ACCURACY
RANGE STUDIED:
0.506 to 2.22 mg/m 3 [1] (91-L samples)
BIAS:
- 1.9%
PRECISION (Sr):
0.072 [1]
ˆ ): 0.062 [1] OVERALL PRECISION (S rT ACCURACY:
± 14.0%
APPLICABILITY: The working range is 0.008 to 1 ppm (0.02 to 2.5 mg/m 3) for a 100-L air sample. This method is also applicable to ceiling measurements.
INTERFERENCES: Other hydrazines, as well as, stannous ion, ferrous ion, zinc, sulfur dioxide, and hydrogen sulfide, may give a positive interference. Negative interferences in the method may occur by oxidation of the 1,1-dimethylhydrazine by hal ogens, oxygen (especially in the presence of copper (I) ion) and hydrogen dioxide.
OTHER METHODS: This revises Method S143 [2]. Method P&CAM 248 [3] describes an acid-coated silica gel sorbent tube/gas chromatographic method for the determination of hydrazine, monomethylhydrazine, 1,1-dimethylhydrazine, and phenylhydrazi ne. Sample stability problems have been noted with P&CAM 248 [4].
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94 1,1-DIMETHYLHYDRAZINE: METHOD 3515, Issue 2, dated 15 August 1994 - Page 2 of 3 EQUIPMENT:
REAGENTS: 1. 2. 3.
4.
5. 6.
1,1-Dimethylhydrazine,* ACS reagent grade. Hydrochloric acid, ACS reagent grade. Collection medium, 0.1 M hydrochloric acid. To 300 mL of distilled water in a 1000-mL volumetric flask, add 8.6 mL of concentrated hydrochloric acid with caution. Mix and bring to volume with distilled water. Phosphomolybdic acid solution. Dissolve 15 g of phosphomolybdic acid in 500 mL distilled water, allow to stand one day, and filter through a fluted paper filter. Water, deionized and distilled. Calibration stock solution, 1 mg/mL. Weigh 500 mg of 1,1-dimethylhydrazine in a 100mL volumetric flask and fill to the mark with 0.1 M hydrochloric acid.
1. Sampler: 25-mL bubbler with 10 mL 0.1 M hydrochloric acid. 2. Personal sampling pump, 0.2 to 1.0 L/min, with flexible polyethylene or PTFE tubing. 3. Glass or non-reactive stopper for bubbler. 4. Glass tube, 5 cm long by 6-mm I.D., loosely packed with glass wool. 5. Spectrophotometer, set at 730 nm. 6. 1-cm spectrophotometer cells. 7. Test tube, large. 8. Volumetric flasks, 50-mL, 100-mL, 500-mL, 1000-mL. 9. Pipets, 10-, 15-, 25, and 50-µL; 10- and 15-mL glass, delivery, with pipet bulb. 10. Graduated cylinders, glass, 10-mL, 25-mL. 11. Water bath at 95 °C. 12. Stopwatch. 13. Thermometer, ca. 0-120 °C.
See SPECIAL PRECAUTIONS.
SPECIAL PRECAUTIONS: 1,1-Dimethylhydrazine may be fatal if inhaled, swallowed or absorbed through the skin [5]. Contact may cause burns to skin and eyes. Vapor may be irritating to the eyes, skin, and mucous membranes. Handle with caution and use appropriate protective equipment.
SAMPLING: 1. 2. 3. 4. 5.
Calibrate each personal sampling pump with a representative sampler in line. Transfer 10 mL 0.1 M hydrochloric acid to a bubbler. Connect outlet arm of bubbler to the glass-wool-packed tube (to prevent splashover into the pump) and then to the sampling pump with the flexible tubing. Sample at an accurately known rate of 0.2 to 1.0 L/min for total sample size of 2 to 100 L. Remove bubbler stem and rinse with 2 mL of 0.1 M hydrochloric acid into bubbler body. Seal bubbler with an inert stopper for shipment in a suitable container in order to prevent damage during transit.
SAMPLE PREPARATION: 6. 7. 8.
Transfer the liquid from the bubbler, quantitatively, to a volumetric flask. Add 10 mL of phosphomolybdic acid solution and bring volume to 50 mL with 0.1 M hydrochloric acid. Transfer an aliquot of this solution to a large test tube and heat to 95 °C for 60 min. Place test tube under running tap water to cool before measurement.
CALIBRATION AND QUALITY CONTROL: 9.
Calibrate daily with at least six working standards to cover the range of 1 to 250 µg 1,1-dimethyl hydrazine per sample. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94 1,1-DIMETHYLHYDRAZINE: METHOD 3515, Issue 2, dated 15 August 1994 - Page 3 of 3 a.
b. c.
d.
Add appropriate aliquots (10, 20, 30, 40 and 50 µL) of calibration stock solution to 10 mL of 0.1 M hydrochloric acid in 50-mL volumetric flasks. Prepare a reagent blank using only 10 mL of 0.1 M hydrochloric acid. Treat with (steps 7 and 8) phosphomolybdic acid solution. Analyze working standards together with samples and reagent blanks (steps 10 through 12) on a spectrophotometer at 730 nm, using a 1-cm cell. Correct standards for reagent blank absorbance. Prepare a calibration graph of absorbance vs. amount (µg) of 1,1-dimethylhydrazine per 50 mL of sample.
MEASUREMENT: 10. 11. 12.
Set spectrophotometer according to manufacturer's recommendations to monitor 730 nm. Fill 1-cm sample cell with sample or standard. Measure absorbance.
CALCULATIONS: 13. 14.
Determine mass, µg, of analyte found in sample (W) and average reagent blank (B). Calculate concentration (C) of 1,1-dimethylhydrazine in the air volume sampled V (L):
EVALUATION OF METHOD: This method was evaluated over the range 0.5 to 2.3 mg/m 3 using 91-L samples [1]. Sampling and measurement precision, SˆrT was 0.062 for samples collected at the OSHA standard. Bias could not be determined owing to instability of the 1,1-dimethylhydrazine in the generator. Collection efficiency of the bubblers was determined to be 99.1% at 2.2 mg/m 3. Sample stability during storage was evaluated at 100 µg 1,1-dimethylhydrazine per sample. Samples showed 101.3% recovery after five days of storage at ambient conditions.
REFERENCES: [1] [2] [3] [4] [5]
Backup Data Report for 1,1-Dimethylhydrazine, prepared under NIOSH Contract 210-76-0123 (1977). NIOSH Manual of Analytical Methods, 2nd e.d., V. 3, S143, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 78-175 (1978). NIOSH Manual of Analytical Methods, 2nd e.d., V. 4, 248, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 78-175 (1978). L.R. Cook, R.E. Glenn and G.E. Podolak, Am. Ind. Hyg. Assoc. J., 40, 69-74 (1979). 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 #17-033-00337-8 from Superintendent of Documents, Washington, D.C. 20402.
METHOD REVISED BY: E.R. Kennedy, Ph.D., NIOSH/DPSE.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94