Page:NIOSH Manual of Analytical Methods - 3510.pdf/1

 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