Chemical Processes & Instrument Development: Instruments

Total Reactive Nitrogen (Nr)

Nr instrument
Nr instrument in the laboratory

Principle of the Measurement

Catalytic conversion of all nitrogen species, except for N2 and N2O, to nitic oxide (NO), and detection by NO-O3 chemiluminescence.

Species Measured

All N-containing species besides N2 and N2O. The method has been verified for a range of organic and inorganic N species.

Time Response

1 second

Detection Limit

Precision on 1s data ±0.1ppbv


± (10% + 0.1ppbv)


This instrument has been used to measure Nr in fire emissions during the 2016 FireLab experiment, as well as a detector for laboratory experiments on the solubility of reduced N species, HNCO, CH3NCO and XCN (X= Cl, Br, and I). The measurement of sources of Nr compounds for the calibration of other instruments has been another important use of this instrument.


James Roberts

Key Publications

Stockwell, C.E., R.A. Washenfelder, A. Kupc, B. Witkowski, R.K. Talukdar, Y. Liu, V. Selimovic, K.J. Zarzana, K. Sekimoto, C. Warneke, R.J. Yokelson, A.M. Middlebrook, J.M. Roberts, Characterization of a catalyst-based conversion technique to measure total particle nitrogen and organic carbon and comparison to a particle mass measurement instrument, Atmospheric Measurement Techniques, doi:10.5194/amt-11-2749-2018, 2018.

Roberts J.M., and Y. Liu, Solubility and solution-phase chemistry of isocyanic acid, methyl isocyanate and cyanogen halides, Atmospheric Chemistry and Physics, doi:10.5194/acp-19-4419-2019, 2019.

Roberts, James M., Chelsea Stockwell, Robert J. Yokelson, Joost de Gouw, Yong Liu, Vanessa Selimovic, Abigail R. Koss, Kanako Sekimoto, Matthew M. Coggon, Bin Yuan, Kyle J. Zarzana, Steven S. Brown, Cristina Santin, Stefan H. Doerr, and Carsten Warneke, The nitrogen budget of laboratory-simulated western US wildfires during the FIREX 2016 FireLab study, Atmospheric Chemistry and Physics, doi:10.5194/acp-20-8807-2020, 2020.