Ranking and classification of non-ionic organic pesticides for environmental distribution: a qsar approach

The partitioning of pesticides into different environmental compartments depends mainly on the physico-chemical properties of the studied chemical. To rank pesticides according to their distribution tendency in various media, we propose a combination of two multivariate approaches: Principal Component Analysis and Hierarchical Cluster Analysis. In such explorative methods we take into account physico-chemical properties like the organic carbon partition coefficient (K _oc), the n-octanol/water partition coefficient (K _ow), water solubility (S _w), vapour pressure (VP) and Henry's law constant (H), being the more relevant to the determination of environmental partitioning.

The 54 studied pesticides of various chemical categories are thus ranked in 4 a priori classes according to their environmental behaviour (sorbed, soluble, volatile and non-volatile/medium class) and finally assigned to the defined four classes by different classification methods (CART, K-NN, RDA) using theoretical molecular descriptors. This QSPR approach allows a rapid indication of the environmental distribution of pesticides starting only from their molecular structure.