Instrument - Cavity Attenuated Phase Shift Nitrogen Dioxide Monitor

Short name:
CAPS NO2 monitor

Full name:
Cavity Attenuated Phase Shift Nitrogen Dioxide Monitor

What is being measured:
Nitrogen dioxide (NO2)

Sampling Protocol:

Environnement S.A


Instrument year :
None specified

Data recording software:

Data analysis software:

Raw data time resolution:
1 minute

Analysis data averaging:

Detection limit:
0.1 ppb

Sensitivity to temperature (and correction method, if applicable): :
Sensitivity coefficient of surrounding temperature (0 to 30 C): <0.2 ppb/K. No correction is applied.

Sensitivity to relative humidity (and correction method, if applicable): :
No impact of RH on measurements

Sampling method:
Direct sampling

Sample preparation method:

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

Length of tubing (cm):

Instrument flow rate:

Tubing inner diameter:
1/4 inch

Tubing material:
FEP Teflon

Chemical identification method:
This Cavity Attenuated Phase Shift nitrogen dioxide (AS32M) monitor operates as an optical absorption spectrometer, utilizing a blue light-emitting diode (LED) as a light source, a sample cell incorporating two high reflectivity mirrors centered at 450 nm, and a vacuum phototube detector. Its efficiency is based on the fact that nitrogen dioxide (NO2) is a broadband absorber of light in the visible region of the spectrum. The light emanating from the cell is directed into a vacuum phototube where the resultant signal is integrated, digitized and sent to the internal computer where all subsequent data processing takes place.

Data analysis method:

Quantification method:

Calibration method:
NO2 gas cylinders and mass flow controllers are used to inject known amounts of NO2 into the chamber. The corresponding NO2 (and NOx) monitor reading for the gas injection are noted.

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

Calibration schedule:

Uncertainty estimation method:

Known interferences:

Link to supplemental information:

Additional notes:

Measurement uncertainty:

Measurement units: