We measured concentration detection functions for the odor detectability of the homologs: formic, acetic, butyric, hexanoic, and octanoic acids. Subjects (14 = n = 18) comprised young (19-37 years), healthy, nonsmoker, and normosmic participants from both genders. Vapors were delivered by air dilution olfactometry, using a three-alternative forced-choice procedure against carbon-filtered air, and an ascending concentration approach. Delivered concentrations were established by gas chromatography (flame ionization detector) in parallel with testing. Group and individual olfactory functions were modeled by a sigmoid (logistic) equation from which two parameters are calculated: C, the odor detection threshold (ODT) and D, the steepness of the function. Thresholds declined with carbon chain length along formic, acetic, and butyric acid where they reached a minimum (ODTs = 514, 5.2, and 0.26 ppb by volume, respectively). Then, they increased for hexanoic (1.0 ppb) and octanoic (0.86 ppb) acid. Odor thresholds and interindividual differences in olfactory acuity among these young, normosmic participants were lower than traditionally thought and reported. No significant effects of gender on odor detectability were observed. The finding of an optimum molecular size for odor potency along homologs confirms a prediction made by a model of ODTs based on a solvation equation. We discuss the mechanistic implications of this model for the process of olfactory detection.
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机译:我们测量了浓度检测功能,用于检测同系物的气味:甲酸,乙酸,丁酸,己酸和辛酸。受试者(14 = n = 18)由年轻(19-37岁),健康,非吸烟者和常识性参与者组成。蒸气通过空气稀释嗅觉测定法,使用针对碳过滤后的空气的三替代强制选择程序和递增浓度法输送。通过气相色谱法(火焰电离检测器)与测试同时确定浓度。嗅觉功能的组和个人通过S形(逻辑)方程建模,从中计算出两个参数:C,气味检测阈值(ODT)和D,函数的陡度。阈值随着沿甲酸,乙酸和丁酸的碳链长度的降低而下降,达到最小(ODT分别为514、5.2和0.26 ppb体积)。然后,它们的己酸(1.0 ppb)和辛酸(0.86 ppb)升高。在这些年轻的常态参与者中,气味阈值和嗅觉敏锐度之间的个体差异低于传统的想法和报道。没有观察到性别对气味检测能力的显着影响。沿着同系物的气味效力的最佳分子大小的发现证实了ODT模型基于溶剂化方程所做的预测。我们讨论了该模型对嗅觉检测过程的机械含义。
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