Can we trust odor databases? Example of t- and n-butyl acetate

The US EPA has exempted t-butyl acetate from VOC regulations, which increases the likelihood that it may replace other solvents in some settings. This investigation probes its chemosensory properties. In Study 1, subjects (n = 29) sought to detect the odor of t-butyl acetate and of n-butyl acetate in forced-choice testing of stable concentrations, analytically confirmed. Subjects sniffed from cones with a high enough volumetric flow to insure against dilution by nonodorized air. A Subject made hundreds of judgments, enough for a psychometric function for each material. The points of 50% detection above chance ("threshold") Occurred at 8 and 2 ppb for t-butyl acetate and n-butyl acetate, respectively. In Study 2, subjects (it = 26) sought to detect vapor with the eye via chemesthesis (sensory irritation) in 10-s exposures. Detection at 50% occurred at 177 and 113 ppm for t-butyl acetate and n-butyl acetate, respectively, more than 10,000 times above that for odor detection. The protocols produced results Of uncommon precision compared to those in often-in is leading archival databases. The nose exhibits Much higher sensitivity than the databases indicate. The collections rarely exhibit accuracy better than +/-1000%. Collection Of accurate data for a VOC can ironically bring oil stricter regulation for just it, a Situation that calls for a strategy to improve the database by collection of new data, importation of better data, and development of quantitative structure-activity modeling. (C) 2009 Elsevier Ltd. All rights reserved.