Gaschromatographic Determination of Carbon Monoxide in Exhaled Air and Blood/Gaschromatographische Bestimmung von Kohlenmonoxid in der Ausatmungsluft und im Blut

The gas chromatographic method described here has been developed for the determination of low carbon monoxide concentrations in air and blood. For the determination in expired air, a 4 ml sample is injected in a molecular sieve 13X column, where the CO is separated from the other gases. The CO is then hydrogenated to methane over a nickel catalyst column heated to 290°C, and the methane is determined with a flame ionization detector. The limit of detection is 0.1 ppm CO in a total sample volume of 4 ml. The standard deviation per single determination is 0.04 to 0.08 ppm CO in the CO concentration range 0.2 to 10 ppm. For the determination in blood, the CO is liberated from the HbCO complex with K3[Fe(CN)6], transferred into a molecular sieve 5A column which is cooled in liquid nitrogen, and then swept into the gas chromatographic set-up used for the determination of CO in air. 0.05 % HbCO can still be detected in a 0.1 ml blood sample. The standard deviation per single determination is 0.02 % HbCO for a total of 1 % HbCO in the blood sample.