AN ALGORITHM FOR NASAL PUNGENCY THRESHOLDS IN MAN

Nasal pungency thresholds (NPT) in man have been determined by Cometto -Muniz and Cain for 44 varied compounds, including esters, aldehydes, ketones, alcohols, carboxylic acids, aromatic hydrocarbons and pyridin e. With the exclusion of acetic acid, 43 of these NPT values are well correlated through the general linear free energy equation of Abraham, leading to the algorithm, log(1/NPT) = -8.519 + 2.154 pi(2)(H) + 3.52 2 Sigma alpha(2)(H) + 1.397 Sigma beta(2)(H) + 0.860 log L-16 n = 43, r(2) = 0.955, SD = 0.27, F = 201 (i) where the independent variables a re solute descriptors: pi(2)(H) is the dipolarity/polarizability, Sigm a alpha(2)(H) and Sigma beta(2)(H) are the overall or effective hydrog en-bond acidity and basicity, and L-16 is the solute Ostwald solubilit y coefficient on hexadecane at 25 degrees C. Surprisingly, the aliphat ic aldehydes and carboxylic acids fit the correlation and with respect to nasal pungency thresholds in man for brief (1-3 s) presentations m ust be regarded as 'nonreactive' compounds. It is suggested mere trans port of the compound from the air stream to the receptor area largely determines the potency to produce pungency. Various chemical propertie s of the receptor area are deduced from the coefficients in Eq. i.