A comparison of flame ionization and ozone chemiluminescence for the determination of atmospheric hydrocarbons

A reactive hydrocarbon analyzer has been constructed on the basis of chemiluminescence reaction with ozone. This detector is designed to operate at varying temperatures which take advantage of the different rates of reaction of the hydrocarbon classes with ozone to yield a measure of their atmospheric reactivity. When operated at high temperatures (170°C), all hydrocarbons will give a chemiluminescence signal. Reported here is a direct comparison of the ozone chemiluminescent detector (operated at a temperature of 170°C) with a flame ionization detector. This comparison was accomplished by connecting a capillary gas chromatograph to each of the two detectors by means of a switching valve. Twenty-seven compounds representing alkanes, alkenes, aromatics, and oxygenated hydrocarbons (aldehydes, ketones, alcohols, and ethers) were studied. For the compounds studied, analytical sensitivities were 10–1000 times better for the chemiluminescence detector. The results of this comparison indicate that the response of the chemiluminescent detector at 170°C correlates with a total carbon detector (flame ionization detection) and that total response is a measure of total carbon in the sample. The chemiluminescent system will be very useful for gas chromatographic detection of atmospheric hydrocarbons, particularly of oxygenates in complex mixtures.