Eliminating Errors in Chemiluminescence NOx Determination in Automobile Exhaust

The chemiluminescence determination of NO, and of NO₂ after conversion to NO, is capable of yielding quantitative results for concentrations ranging from ppm to 1%. In using the chemiluminescence method for automobile exhaust, fast response and specificity are additional benefits. There are many possible sources of error in sampling, transporting, and analyzing auto exhaust samples, particularly when appreciable amounts of NO₂ may be present. This paper discusses sources of error and how to detect and minimize or eliminate them.