Chemical senses are highly sensitive to minute amounts of odorants in the environment. Therefore, when testing the responses of olfactory receptors, substances of highest purity are used, generally 95% or 99%, i.e., with impurities of 5% or 1%. We report a case where an impurity of 0.0006% was sufficient to explain the full response of an olfactory receptor in a test situation. We demonstrate why all experiments investigating the selectivity of odor receptors have to be performed with gas-chromatography-purified odors to eliminated potential impurity artifacts:

M. Paoli, D. Münch, A. Haase, E. Skoulakis, L. Turin and C. G. Galizia, Minute Impurities Contribute Significantly to Olfactory Receptor Ligand Studies: tales from Testing the Vibration Theory.,eNeuro  DOI: https://doi.org/10.1523/ENEURO.0070-17.2017