Modelling and prediction of soil sorption coefficients of non-ionic organic pesticides by molecular descriptors

Soil sorption coefficients (K-OC) of 185 non-ionic organic heterogeneous pe sticides have been studied searching for quantitative structure-property re lationships (QSPRs). The chemical description of pesticide structure has be en made in terms of some molecular descriptors: count descriptors, topologi cal indices, information indices, fragment-based descriptors and weighted h olistic invariant molecular (WHIM) descriptors; these last are statistical indices describing size, shape, symmetry and atom distribution of molecules in the three-dimensional space. Three new topological indices derived from the electrotopological state indices of Kier and Hall were proposed. Multi ple linear regression analysis was performed after previous selection of th e descriptors mostly correlated to the response by Genetic Algorithms. The obtained results confirm the capability of the proposed approach to give pr edictive models for one of the most important partition properties, such as soil sorption coefficient (K-OC). (C) 2000 Elsevier Science Ltd. All right s reserved.