NITROUS OXIDE
N2O
MW: 44.01
METHOD: 6600, Issue 2
CAS: 10024-97-2
6600
RTECS: QX1350000
EVALUATION: FULL
OSHA : no standard NIOSH: 25 ppm ACGIH: 50 ppm (1 ppm = 1.80 mg/m 3 @ NTP)
Issue 1: 15 February 1984 Issue 2: 15 August 1994
PROPERTIES: gas; BP -88.46 °C; d = 1.53 (air =1)
SYNONYMS: hyponitrous acid anhydride; laughing gas.
SAMPLING SAMPLER:
AMBIENT AIR OR BAG SAMPLE
VOL-MIN: -MAX:
at least 2 spectrophotometer cell volumes no maximum volume
MEASUREMENT TECHNIQUE:
LONG-PATHLENGTH PORTABLE INFRARED SPECTROPHOTOMETER (FIELD READOUT)
ANALYTE:
nitrous oxide
SAMPLE STABILITY:
bag samples stable 2 h @ 25 °C
OPERATION:
according to manufacturer's instructions
BLANKS:
use uncontaminated air
ANALYTICAL WAVELENGTH:
4.48 µm
ACCURACY RANGE STUDIED:
10 to 1000 ppm
BIAS:
none known
PATHLENGTH:
0.5 m to 40 m (function of desired concentration range)
CALIBRATION:
closed-loop dilution of N 2O
RANGE:
10 ppm to > 1% N 2O in air
ESTIMATED LOD: ca. 1 ppm N 2O @ 10-m pathlength; varies with pressure and instrument PRECISION (Sr):
0.01 [1] (within-instrument)
ˆ ): 0.013 [1] OVERALL PRECISION (S rT (between-instrument) ACCURACY:
± 2.5%
APPLICABILITY: The working range of this method is 10 ppm (v/v) to more than 1% (v/v) N 2O. This method may be used for the sequential determination of two or more analyses by changing the analytical wavelength and pathlength.
INTERFERENCES: In common application (i.e., hospital, dental or veterinary operatory), there are no identified interferences.
OTHER METHODS: The criteria document on waste anesthetic gases [2] also describes an infrared method.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
