Instrument - Thermo Fisher Model 42i Chemiluminescence NO-NO2-NOx Analyzer
Thermo Fisher Model 42i Chemiluminescence NO-NO2-NOx Analyzer
What is being measured:
Data recording software:
Data analysis software:
Raw data time resolution:
Analysis data averaging:
Sensitivity to temperature (and correction method, if applicable):
Sensitivity to relative humidity (and correction method, if applicable):
Sample preparation method:
Sample residence time (chamber to instrument) (seconds):
Length of tubing (cm):
Instrument flow rate:
Tubing inner diameter:
Chemical identification method:
This instrument measures NO using its chemiluminescent reaction with ozone. It also measures total NOx by passing the sample flow through a molybdenum catalyst to convert it to NO, before measuring this in the same manner. NO2 concentration is calculated by subtracting the NO measurement from the total NOx measurement. The catalyst also converts some NOy species including HONO to NO and as such these are detected as "NO2."
Data analysis method:
Calibration is performed using standard tanks of NO and NO2.
Calibration drift estimate:
Uncertainty estimation method:
Uncertainty from factory specifications is +- ~1%. Uncertainty arising from error in dilution of calibration gases is likely closer to +- 10%.
NOy species, most notably HONO in our reaction systems, are detected as "NO2"
Link to supplemental information: