Instrument - Ozone photometric analyzer, NOx chemiluminescence analyzer, temperature and relative humidity probes
O3NOxTRH - clone test
Ozone photometric analyzer, NOx chemiluminescence analyzer, temperature and relative humidity probes
What is being measured:
Horiba, Teledyne, and Vaisala
Not sure, contact lab to inquire
Data recording software:
Data analysis software:
Raw data time resolution:
Analysis data averaging:
> 1 ppb for ozone, > 0.5 ppb for NOx, within 2% for T/RH
Sensitivity to temperature (and correction method, if applicable):
No temperature sensitivity that we know of
Sensitivity to relative humidity (and correction method, if applicable):
NOx monitor is very sensitive to RH, it takes a while to re-equilibrate. We don't correct for this, just let it warm up appropriately
Direct sampling from the chamber through teflon tube for the O3/NOx. The T and RH probes are inserted into the chamber.
Sample preparation method:
No sample prep
Sample residence time (chamber to instrument) (seconds):
Length of tubing (cm):
Instrument flow rate:
Tubing inner diameter:
Chemical identification method:
For the Ozone, it measures the UV absorbance. For the NO, it measures its chemiluminescence when reacting with excess O3. For NO2, it decomposes the NO2 to NO via a heated molybdenum catalyst and measures the NO. This NOx analyzer also measures other things that can decompose into NO as NOx, such as methyl nitrite (CH3ONO) and other species.
Data analysis method:
Data are recorded with labview using the analog signals. These data come as is.
The instrument has calibration factors for the desired species and applies them natively.
NO and NO2 are calibrated with primary standard gas mixtures. O3 was calibrated using FTIR at one point. RH is calibrated with a series of saturated salt solutions. T is calibrated at the boiling and melting point of water.
Calibration drift estimate:
Low (on the order of weeks)
Uncertainty estimation method:
Uncertainties come from signal noise, deviations from calibration line, propagated errors from the calibration, and other factors.
O3 measurement is known to have an interference from ppm levels of H2O2. NOx analyzer is sensitive to certain NOy.
Link to supplemental information: