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

• Published in: Atmospheric environment (1994) Vol. 43; no. 16; pp. 2591 - 2601
• Main Authors: Cain, William S., Schmidt, Roland
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.05.2009; Elsevier
• Subjects: Analytical chemistry; Chemistry; Chromatographic methods and physical methods associated with chromatography; Exact sciences and technology; Gas chromatographic methods; n-Butyl acetate; Ocular irritation; Odor threshold; Psychophysics; t-Butyl acetate; t-Butyl acetate; Psychophysics; Ocular irritation; Odor threshold; n-Butyl acetate; Sensitivity analysis; Volatile organic compound; Modeling; Gas chromatography; Detection threshold; Database; Regulation; Odor; Organic compounds
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/j.atmosenv.2009.02.024

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 ( n = 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-misleading 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 on 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.