Monitoring of Xylene, Toluene, Carbon Dioxide, Carbon Monoxide and Hydrocarbons Using a Photoacoustic Infrared Spectroscopy Method

The photoacoustic infrared detection method can be used to measure almost any gas which absorbs infrared light. Such an instrument was tested during a dry saturation dive with a duration of 28 days. Throughout the dive samples were taken from the living chamber at regular intervals of one hour and analyzed with respect to carbon monoxide, carbon dioxide, xylene, toluene and total hydrocarbons. The same gases were also analyzed by conventional methods. The photoacoustical infrared detection method gave nearly the same results as the standard monitoring instruments. However, a major discrepancy was experienced for xylene and total hydrocarbons when compared to the results from a gaschromatographic mass selective detection. The photoacoustic infrared equipment had a low drift during the test period and was easy to operate. This instrument may have a potential as monitoring equipment for closed environments such as space missions and diving operations where regular monitoring of trace contaminants is important.