Page:NIOSH Manual of Analytical Methods - 6700.pdf/1

 NITROGEN DIOXIDE (Diffusive sampler)

NO2

MW: 46.01

METHOD: 6700, Issue 2

CAS: 10102-44-0

EVALUATION: FULL

OSHA : C 5 ppm NIOSH: STEL 1 ppm/15 min ACGIH: 3ppm; STEL 5 ppm (1 ppm = 1.881 mg/m3 @ NTP)

6700

RTECS: QW9805000

Issue 1: 15 February 1984 Issue 2: 15 January 1998 PROPERTIES:

yellowish-brown fuming liquid or reddish-brown gas; BP 21 C; MP -9.3 C; d 1.448 @ 20 C; vap density (air=1) 1.59

SYNONYMS: nitrogen peroxide, dinitrogen tetroxide, Azote

SAMPLING SAMPLER:

SAMPLING TIME

SHIPMENT: SAMPLE STABILITY:

BLANKS:

DIFFUSIVE SAMPLER (Palmes tube with three triethanolaminetreated screens) [1]

- MIN: 15 min @ 5 ppm - MAX: 8 h @ 10 ppm

TECHNIQUE:

VISIBLE ABSORPTION SPECTROPHOTOMETRY

ANALYTE:

nitrite ion (NO2-)

REAGENT:

aqueous solution of sulfanilamide, H3PO4, and N-1-naphthylethylenediamine dihydrochloride

WAVELENGTH:

540 nm

PATHLENGTH:

1 cm

CALIBRATION:

solutions of NaNO2 in reagent

RANGE:

0.13 to 8.5 µg NO2 per sample [2]

routine

use sampler within 1 month after preparation; analyze within 1 month after sampling 2 to 10 field blanks per set

ACCURACY RANGE STUDIED:

1.2 to 80 ppm-h (0.13 to 8.5 µg NO2 per sample) [2]

BIAS: OVERALL PRECISION ( ACCURACY:

MEASUREMENT

6.8% rT

):

ESTIMATED LOD: 0.01 µg NO2 per sample PRECISION ( r):

0.05 [2]

0.06 [3] ± 16.0%

APPLICABILITY:The working range is 1.2 to 80 ppm-h [2]. The method is applicable for ceiling and short-term exposure measurements. In the development of this passive sampler, it was assumed that NO2 was completely converted to nitrite ion [1]. Incomplete conversion of NO2 to nitrite ion (Saltzman factor <1) will cause a negative bias [1]. Diffusive samplers have a lower collection efficiency at lower pressure (-7% @ 5500 m altitude) [4].

INTERFERENCES:In very dusty environments, particles may deposit on the inside surface of the sampler. Resuspension of the dust in analytical reagent can give a positive bias in the spectrophotometric reading. OTHER METHODS: Short-term and long-term detector tubes, passive indicator tubes, and various other diffusive samplers and electrochemical instruments have been used to sample for NO2. NMAM Method 6014 [5] also uses an active solid sorbent sampling method with similar color development.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition