# Monomethylhydrazine (3510)

​MONOMETHYLHYDRAZINE
CH3NHNH2
MW: 46.07
METHOD: 3510, Issue 1
CAS: 60-34-4 EVALUATION: FULL
OSHA : C 0.2 ppm (skin) NIOSH: C 0.04 ppm/120 min; carcinogen ACGIH: C 0.2 ppm (skin; Suspect Carcinogen) (1 ppm = 1.88 mg/m 3 @ NTP)
PROPERTIES:
3510
RTECS: MV5600000 Issue 1: 15 August 1994
liquid; MP -52.4 °C; BP 87.5 °C; d 0.874 g/mL @ 25 °C; VP 6.6 kPa (49.6 mm Hg) @ 25 °C; vapor density (air = 1) 1.59; flammability limits in air 2.5 to 97% v/v
SYNONYMS: hydrazomethane; 1-methylhydrazine; methylhydrazine
SAMPLING SAMPLER:
BUBBLER (0.1 M hydrochloric acid)
MEASUREMENT TECHNIQUE:
VISIBLE SPECTROPHOTOMETRY
ANALYTE:
monomethylhydrazine phosphomolybdic acid complex
FLOW RATE: 0.5 to 1.5 L/min VOL-MIN: -MAX:
3 L @ 0.2 ppm 20 L
DILUTION:
7.5 mL of phosphomolybdic acid solution and 0.1 M hydrochloric acid to 25 mL
SHIPMENT:
remove bubbler stem and rinse with 0.1 M hydrochloric acid; seal bubblers with nonreactive stopper
WAVELENGTH:
730 nm; 5-cm cell
CALIBRATION:
standard solutions of monomethylhydrazine sulfate in 0.1 M hydrochloric acid
RANGE:
1 to 100 µg per sample [1]
SAMPLE STABILITY:
at least five days @ 25 °C
BLANKS:
2 to 10 field blanks per set ESTIMATED LOD: 0.7 µg per sample [2] ACCURACY
RANGE STUDIED:
0.17 to 0.78 mg/m 3 [1] (20-L samples)
BIAS:
- 3.4%
PRECISION (Sr):
0.029 @ 3.9 to 16.0 µg per sample [1]
ˆ ): 0.106 [1] OVERALL PRECISION (S rT ACCURACY:
± 21.6%
APPLICABILITY: The working range is 0.027 to 2.7 ppm (0.05 to 5 mg/m 3) for a 20-L air sample. This method is applicable to STEL and ceiling measurements.
INTERFERENCES: Other hydrazines, as well as stannous ion, ferrous ion, zinc, sulfur dioxide and hydrogen sulfide, may give a positive interference. Negative interference in the method may occur by oxidation of the monomethylhydrazine by haloge ns, oxygen( especially in the presence of copper (I) ions) and hydrogen dioxide.
OTHER METHODS: This revises Method S149 [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 phenylhydrazin e, but sample stability problems have been noted with it [4].
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94 ​MONOMETHYLHYDRAZINE: METHOD 3510, Issue 1, dated 15 August 1994 - Page 2 of 3 EQUIPMENT:
REAGENTS: 1. 2. 3.
4.
5. 6.
Methylhydrazine sulfate *, 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 before use through a fluted paper filter. Water, deionized and distilled. Calibration stock solution, 1 mg/mL. Weigh 100 mg of methylhydrazine sulfate in a 100-mL volumetric flask and fill to the mark with 0.1 M hydrochloric acid.
See Special Precautions
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.
Sampler: 25-mL bubbler with 15 mL 0.1 M hydrochloric acid. Personal sampling pump, 1.5 L/min, with flexible polyethylene or PTFE tubing. Glass or non-reactive stopper for bubbler. Glass tube, 5 cm long by 6-mm I.D., loosely packed with glass wool. Spectrophotometer, set at 730 nm. Spectrophotometer cells, 5-cm. Test tube, large. Volumetric flasks, 25-mL, 100-mL, 500-mL, 1000-mL. Pipets, 10-, 15-, 25-, and 50-µL; 10- and 15mL glass, delivery, with pipet bulb. Graduated cylinders, glass, 10-mL, 25-mL. Water bath at 87 °C. Stopwatch. Thermometer, ca. 0-120 °C.
SPECIAL PRECAUTIONS: Monomethylhydrazine may be fatal if inhaled, swallowed or absorbed through skin contact [5,6]. Contact may cause burns to skin and eyes. Vapor may cause irritation to eyes, nose, throat, and skin. 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 15 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 between 0.5 and 1.5 L/min for a total air sample of 3 to 20 L. Remove bubbler stem and rinse with 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 25-mL volumetric flask. Add 7.5 mL of phosphomolybdic acid solution and bring volume to 25 mL with 0.1 M hydrochloric acid. Transfer an aliquot of this solution to a large test tube and heat to 87 °C for 50 min. Place test tube under running tap water to cool before measurement.
CALIBRATION AND QUALITY CONTROL: 9.
Prepare working standards over the range of 10 to 100 µg/25 mL. a. Add aliquots (10, 25, 50 and 100 µL) of calibration stock solution to 15 mL of 0.1 M hydrochloric acid in 25-mL volumetric flasks. Prepare a reagent blank using only 15 mL of NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94 ​MONOMETHYLHYDRAZINE: METHOD 3510, Issue 1, dated 15 August 1994 - Page 3 of 3
b. c. d. e.
f.
0.1 M hydrochloric acid. Add 7.5 mL of phosphomolybdic acid solution to all standards and blank and bring the volume up to 25 mL with 0.1 M hydrochloric acid. Transfer aliquots of these solutions to large test tubes and heat to 87 °C for 50 min. Place test tubes under running tap water to cool before measurement. Analyze working standards together with samples and reagent blanks (steps 10 through 12) on a spectrophotometer at 730 nm, using a 5-cm cell. Correct standards for reagent blank absorbance. Prepare a calibration graph of absorbance vs. amount (µg) of monomethylhydrazine per sample.
MEASUREMENT: 10. 11. 12.
Set spectrophotometer according to manufacturer's recommendations and to conditions on p. 3510-1 to monitor 730 nm. Fill 5-cm sample cell with sample or standard. Measure absorbance.
CALCULATIONS: 13. 15.
Determine mass, µg, of monomethylhydrazine found in the sample (W) and blank (B) from the calibration graph. Calculate concentration of monomethylhydrazine in the actual air volume, V (L):
EVALUATION OF METHOD: This method was evaluated over the range 0.17 to 0.78 mg/m 3 using 20-L samples [1,2]. Overall sampling and measurement precision, SˆrT, was 0.106. Collection efficiency of the bubblers was determined to be 96.5% at 1.7 mg/m 3 for a 20-L sample. Sample stability during storage was evaluated at 8 µg monomethylhydrazine per sample. Samples showed 104.4% recovery after five days of storage at ambient conditions compared to one-day old samples.
REFERENCES: [1] [2] [3] [4] [5] [6]
Backup Data Report for Monomethylhydrazine, prepared under NIOSH Contract 210-76-0123 (1977). NIOSH Manual of Analytical Methods, 2nd. ed., V. 4, S149, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 78-175 (1978). NIOSH Manual of Analytical Methods, 2nd. ed., V. 4, P&CAM 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 Criteria for a Recommended Standard....Occupational Exposure to Hydrazines, DHEW (NIOSH) Publ. No. 78-122 (1978). NIOSH/OSHA Occupational 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