ABSTRACT
Carbon monoxide (CO) is a toxic gas and as such it is monitored in the ambient air for personal safety reasons. CO is also an indicator of incomplete combustion, and therefore it is measured to optimize boilers and other combustion processes. Methods used for analysis of carbon monoxide at atmospheric levels require calibration with gas mixtures of known concentration. Smaller samples may be prepared in plastic bags by injecting pure carbon monoxide from a gas syringe into a stream of diluent gas metered accurately into the bag with a flow device such as a wet test meter. Nondispersive infrared analysis is the reference method for the US National Air Quality Standard for carbon monoxide. A precolumn holds back carbon dioxide, water, and hydrocarbons other than methane from reaching the molecular sieve separation column. Some colorimetric methods are also available for carbon monoxide analysis, although, in general, the sensitivity and precision are low for atmospheric work.
