Monitoring hydrogen sulfide in simulated breath of anesthetized subjects

Abstract

Human breath can be a complex mixture of trace gases in humid air, with the addition of various anesthetizing agents it becomes even more complex and can present a challenge for the accurate quantification of components. The purpose of this paper was to investigate the quantification of H2S as a function of several potential matrix/interference compounds using negative-ion atmospheric pressure chemical ionization with mass spectrometric detection. Analysis was performed by humidifying zero-air and adding various compounds that would be encountered in a perioperative situation. Nitrous oxide, carbon dioxide and to a lesser extent humidity have significant effects on the instrument response to hydrogen sulfide concentration, while halogenated species were found to have little if any complicating effect. It was found that H2S can be accurately quantified by using either [SO3]− or [SO2]−/[SO3]−, both of which eliminate the response variability due to interferences.