Foam-Eliminatory Purge-and-Trap Technique Using a Functional PTFE Membrane and Needle-Type Extraction Device to Determine Flavors in Drink Samples

A simple and sensitive method for determining flavor compounds in foamable liquid samples was developed using the purge-and-trap method with the addition of glass wool and a functional porous polytetrafluoroethylene (PTFE) membrane. Flavor compounds purged from sample solutions were trapped by a needle-type extraction device. The functional PTFE membrane, which retained the aqueous sample while allowing purge gas to pass, was fixed on a glass solid-phase extraction cartridge. Hence, purge gas was continuously introduced into the sample solution from the bottom of the cartridge. To trap the foam, 0.4 g of glass wool was fixed in the sample headspace, and headspace gas was collected using a needle-type extraction device placed on the upper side of the wool. During the purge process, although foam climbed through the cartridge, it was adsorbed on the glass wool. However, the flavor compounds were not adsorbed on the inactive glass wool surface as confirmed in this study. This method does not require the dilution of sample solutions or the adding of antifoam agents to sample solutions. This simple and inexpensive construction enables the sensitive detection of flavor compounds.