New alternatives for estimating the octanol/water partition coefficient and water solubility for volatile organic compounds using GLC data (Kovàts retention indices)
Felicia Spafiu, Alice Mischie, Petre Ioniță, Adrian Beteringhe, Titus Constantinescu, Alexandrù T. Balaban · ARKIVOC · 2009
New possibilities for estimating octanol/water partition coefficients (logP) and the water solubility (S w ) were investigated using Kovàts retention indices (I) obtained from GLC retention data for 132 volatile organic compounds belonging to 7 different chemical classes (hydrocarbons, alcohols, aldehydes, ketones, carboxylic acids, esters and halogen compounds).Application of the multilinear regression method led to six equations, all involving index I, as follows: (i) direct correlation logP vs.I (eq.1); (ii) logP vs.I , molar refractivity, and surface tension (eq.2); (iii) logP vs.I and structural characteristics (eqs.3, 4 and 6); (iv) logP vs. the I/S w ratio (eq.5).Excepting eq. 1 (which showed relatively weak correlations), eqs. 2 -6 can provide reliable values for logP and for logS w as proved by the significant statistical parameters.The general models presented through eqs. 2 -6 may also be applied in estimation of other biological and/or ecological important properties, which are linearly dependent on the logP or log S w values.By generalization, a new calculation method is suggested (eq.7), in order to allow the estimation of logP or logS w in terms of the number of bonds and the Kovàts retention index.