UC San Diego

Using 1-butanol and 2-heptanone, representatives of VOCs found in indoor air, we investigated the rules for sensory detection of binary mixtures relative to the detection of the single components. Stimuli were measured via gas chromatography, and sensory responses via a two-alternative forced-choice procedure, with presentation of ascending concentrations. Results for individual chemicals and mixtures were expressed as stimulus-response detectability functions (i.e., psychometric functions). The rate of increase of detectability was similar for butanol and heptanone and was larger for the trigeminal responses (nasal pungency and eye irritation) than for the olfactory response (odor). For all three sensory endpoints, the mixtures became more detectable with increasing amounts of the components mixed. The increase followed a model of agonism whereby introduction of a second component can be seen as introduction of more of the first component. Further work will address the roles of number and chemical identity of components in the sensory detection of mixtures.