Page:NIOSH Manual of Analytical Methods - 3515.pdf/1

This page needs to be proofread.

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