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ACETIC ANHYDRIDE

(CH3CO)2O

MW: 102.09

METHOD: 3506, Issue 2

CAS: 108-24-7

EVALUATION: FULL

OSHA : 5 ppm NIOSH: C 5 ppm ACGIH: C 5 ppm (1 ppm = 4.17 mg/m 3 @ NTP)

3506

RTECS: AK1925000 Issue 1: 5 May 1985 Issue 2: 15 August 1994

PROPERTIES: liquid; d 1.080 g/mL @ 15 °C; BP 139 °C; MP -73 °C; VP 4 mm Hg @ 20 °C; explosive range 2.9 to 10.3% v/v in air

SYNONYMS: acetic acid anhydride; acetyl oxide

SAMPLING SAMPLER:

LIQUID IN BUBBLER (mixed bubbler with 10 mL alkaline hydroxylamine)

FLOW RATE:

0.2 to 1.0 L/min

VOL-MIN: -MAX:

25 L 100 L

SHIPMENT:

hand delivery or special bubbler cases

SAMPLE STABILITY:

≥ 4 days @ 25 °C [1]

BLANKS:

2 to 10 field blanks per set

ACCURACY RANGE STUDIED:

9.35 to 37.4 mg/m 3 [1] (100-L samples)

BIAS:

4.9%

MEASUREMENT TECHNIQUE:

VISIBLE ABSORPTION SPECTROPHOTOMETRY

ANALYTE:

acetic anhydride-hydroxylamine-ferric chloride complex

FINAL VOLUME:

50 mL

WAVELENGTH:

540 nm

CALIBRATION:

complexed acetic anhydride standards

RANGE:

0.5 to 4 mg acetic anhydride per sample [2]

ESTIMATED LOD:

0.05 mg acetic anhydride per sample

PRECISION (Sr):

0.021 @ 1 to 4 mg acetic anhydride per sample [1]

ˆ ): 0.060 [1] OVERALL PRECISION (S rT ACCURACY:

± 15.3%

APPLICABILITY: The working range is 1.2 to 10 ppm (5 to 40 mg/m 3) for a 100-L air sample. The upper limit of the range may be extended by diluting the sample with the collection medium prior to color development. The method is sensitive enough for short-term (>5 min) determinations if a 5-cm or longer cuvette is used.

INTERFERENCES: Any substance containing a hydrolyzable carbonyl group, such as esters, acid chlorides, and aldehydes, is an interference. The most likely interference to coexist with acetic anhydride in air is ketene [2,3].

OTHER METHODS: This revises Method S170 [2].

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94