Short name:
NOx Box

Full name:
NO-NO2-NOx Chemiluminescence Analyzer

What is being measured:
Nitrogen oxides

Sampling Protocol:
Online

Manufacturer:
Thermo Scientific

Model:
42C

Instrument year :
None specified

Data recording software:
NI DAQ with Labview, recorded on MICAS-X

Data analysis software:

Raw data time resolution:
10 s

Analysis data averaging:

Detection limit:
5 ppb

Sensitivity to temperature (and correction method, if applicable): :

Sensitivity to relative humidity (and correction method, if applicable): :

Sampling method:
Direct sampling from chamber

Sample preparation method:

Sample residence time (chamber to instrument) (seconds):

Length of tubing (cm):

Instrument flow rate:

Tubing inner diameter:

Tubing material:

Chemical identification method:
Chemiluminescence of NO2 at 405 nm after converting all NOx to NO and then reacting with excess O3 in one channel, and only measuring NO2 in another channel, then performing a subtraction of NOx - NO2 to get NO concentrations.

Data analysis method:

Quantification method:
Concentration is as reported by the instrument.

Calibration method:
Adding known amounts of NO or NO2 to the chamber from a dark bulb of known volume, where the chamber volume is calibrated by addition of CO2 and monitoring the change in concentration of CO2.

Calibration drift estimate:
Low (on the order of weeks)

Calibration schedule:

Uncertainty estimation method:
Uncertainty is +/- 15%, estimated from standard deviations of replicate measurements, introduction of standard chemical into the chamber, including conversion of NO to NO2 from our NO standard cylinder.

Known interferences:
Nitrites (i.e. methyl nitrite) used for OH generation by photolysis are read as NO2 on the NOx analyzer.

Link to supplemental information:

Additional notes:

Measurement uncertainty:
All units have uncertainties of 15% of absolute value.

Measurement units:
All measurements from this instrument have units of ppmv.