Method 6014

Nitric oxide & nitrogen dioxide by visible absorption spectrophotometry

This method is for the determination of nitric oxide (NO) and nitrogen dioxide (NO2). The sample is collected on a set of three tubes in series.  The first tube is a triethanolamine treated molecular sieve, the second tube is an oxidizer tube and the third tube is a triethanolamine treated molecular sieve.  Nitrogen dioxide is collected on the first tube.  The oxidizer tube is discarded after sampling.  Nitric oxide is collected on the third tube.  The samples are analyzed by visible absorption spectrophotometry.

The working range for NO is 1 to 50 ppm (1.3 to 61 mg/m³) for a 1.5-L air sample. The working range for NO2 is 0.5 to 25 ppm (1 to 47 mg/m³) for a 3-L air sample. The lower sampling rate for NO is to allow collection of oxidized NO on the back sorbent section. At the lower rate, both NO and NO2 may be determined simultaneously.

This method is based on that of Willey, et al. and combines S321, S320, and P&CAM 231 in a revised format. OSHA methods ID-182 and ID-190 use the same sampler, with measurement by ion chomatography.

(NIOSH Issue 1: 15 August 1994)


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Method Data

Hold Times, Preservatives, Preps, Collection, Analytical & Documentation
Holding Time:   The samples are stable at least 7 days @ 25°C.
Preservatives:   Keep at 25°C.
Required Preps:   Two triethanolamine treated molecular sieves, 800mg oxidizer tube, SKC 226-40
Collection Method:   NO: flow rate 0.025 L/min. with a 1.5L to 6L collection volume. NO2 flow rate 0.025 L/min. to 0.2 L/min. with a 1.5L to 6L collection volume.
Analytical Methodology:   Visible absorption spectrophotometry
Documentation:   6014

Analyte List*

Analyte Formula CAS Number Detection Limit
Nitric oxide
Nitrogen dioxide

* The analytes and detection limits listed for each method represent the typical detection limits and analytes reported for that particular method. Keep in mind that analyte lists may vary from laboratory to laboratory. Detection limits may also vary from lab to lab and are dependent upon the sample size, matrix, and any interferences that may be present in the sample.