Concentration-detection functions for the odor of homologous n-acetate esters

Abstract

Using air-dilution olfactometry, we measured concentration-response functions for the odor detection of the homologous esters ethyl, butyl, hexyl, and octyl acetate. Stimuli were delivered by means of an 8-station vapor delivery device (VDD-8) specifically designed to capture odor detection performance by humans under environmentally realistic conditions. Groups of 16–17 (half female) normosmic (i.e., having a normal olfaction) non-smokers (ages 18–38) were tested intensively. The method involved a three-alternative forced-choice procedure against carbon-filtered air, with an ascending concentration approach. Delivered concentrations were confirmed by gas chromatography before and during actual testing. A sigmoid (logistic) model provided an excellent fit to the odor detection functions both at the group and individual levels. Odor detection thresholds (ODTs) (defined as the half-way point between chance and perfect detection) decreased from ethyl (245 ppb by volume), to butyl (4.3 ppb), to hexyl acetate (2.9 ppb), and increased for octyl acetate (20 ppb). Interindividual threshold variability was near one and always below two orders of magnitude. The steepness of the functions decreased slightly but significantly with carbon chain length. The outcome showed that the present thresholds lie at the very low end of those previously reported, but share with them a similar relative trend across n-acetates. On this basis, we suggest that a recent quantitative structure-activity relationship (QSAR) for ODTs can be applied to these and additional optimized data, and used to describe and predict not just ODTs but the complete underlying psychometric odor functions.

An assessment of air quality reflecting the chemosensory irritation impact of mixtures of volatile organic compounds

“…(4) for VOCs that act through specific effects VOCs that act through physical effects, and so we then added VOCs that act specifically and for which ODT values were available (Devos et al, 1990;Nagata, 2003;Cometto-Muñiz and Cain, 1990, 1994Cometto-Muñiz et al, 1998aCometto-Muñiz and Abraham, 2008a, 2008c, 2009a, 2009b, 2010bHellman and Small, 1974;Rodriguez et al, 2011;Czerny et al, 2011). We also included VOCs that act specifically, and had been studied in the mouse assay (Alarie et al, 1995(Alarie et al, , 1996(Alarie et al, , 1998Schaper 1993).…”

“…We intend to pursue this in the future. Devos et al, 1990 3.868 Mouse test, Alarie et al, 1995Alarie et al, , 1996Alarie et al, , 1998Schaper, 1993 0.469 Inhalation anesthesia, Abraham et al, 2008 6.730 Tadpole narcosis, Bowen et al, 2006 8.616 Inhalation convulsions, Abraham and Acree, 2009 7.040 Draize eye test, Abraham et al, 2003 0.526 Inhalation anesthesia, Davies et al, 1974Davies et al, , 1976 4.746 a Cometto-Muñiz and Cain, 1990Cain, , 1991Cain, , 1993Cain, , 1994Cometto-Muñiz et al, 1998a Cometto-Muñiz and Abraham, 2008aAbraham, , 2008cAbraham, , 2009aAbraham, , 2009bAbraham, , 2010aAbraham, , 2010b The probability that a given air sample containing a number of VOCs could elicit sensory irritation, denoted as Qmix, can then be calculated from the response addition expression, Eq. (6), where the letters a, b. c. … represent different VOCs.…”

QSPR Modeling of Odor Threshold of Aliphatic Alcohols Using Extended Topochemical Atom (ETA) Indices

“…Thus, the ambiguous nature of odorant receptors along with various characteristics of olfactory data has enhanced the urge to gain information about threshold data for odor of various compounds which have its wide application in the field of bioscience, food chemistry and environmental pollution. [3][4][5] In relation to the mechanism behind odorant binding, earlier it was proposed that odorants of similar property activates common receptor subtypes. But later, it was proved to be wrong as it was seen that homologous oxygenated aliphatic molecules though having similar molecular properties do not share similar quality of odor.…”

Methodological Factors in Odor Detection by Humans

“…Odor thresholds can also help us understand the genetics of human olfaction and characterize the fundamental response properties of the olfactory system (Wysocki and Beauchamp 1984;Menashe et al 2007;Wise et al 2007;Cometto-Muñiz et al 2008;Miyazawa et al 2008;Cometto-Muñiz and Abraham 2009). Given both the applied and basic significance of data on human odor detection, it is unfortunate that published thresholds for a given compound often differ by orders of magnitude (Amoore and Hautala 1983;Devos et al 1990;van Gemert 1999).…”

“…A weak stimulus could follow a stronger one, which might be particularly problematic in an adaptation-prone sensory system. For this reason, some who have measured psychometric functions for odor detection have favored a blocked, ascending order of presentation, i.e., concentration ascends from the bottom to the top of the range, with a relatively long pause after the highest concentration is presented (e.g., Wise et al 2007;Cometto-Muñiz et al 2008;Miyazawa et al 2008;Cometto-Muñiz and Abraham 2009). Order of presentation seems to make little or no difference for measured odor thresholds in rodents (Walker and O'Connell 1986).…”