Amplification of gas chromatographic-olfactometric signal by ethanol.

An indication of the amplifying effect of ethanol vapors from a humidifier on the perceived odor intensity of eluting odorants was discovered in previous GC--olfactometric (GC-O) experiments. In this study were tested 12 volatiles belonging to various chemical classes to confirm this phenomenon. Two methods were used: the normal GC-O design, whereby panelists smell the effluent incessantly during the whole run, and a design applicable in a target-oriented quantitative GC-O, whereby panelists start sniffing just a short time before the olfactory event starts. Two hydroalcoholic solutions and pure water were put into the humidifier and tested in both designs. Continuous aspiration of ethanol vapors caused a decrease of average intensity for most of the selected volatiles. In contrast, a significant amplifying effect of ethanol on panel intensity was observed in the target-oriented design for most of the compounds. This observation was confirmed with an independent panel. The proposed modification of a standard GC-O procedure could remarkably enhance the performance of GC-O studies oriented on a few target chemicals.