Response Surface Analysis of Bioconcentration by Chlorinated Organics Using Molecular Connectivity

Abstract

Bioconcentration data for chlorinated organic compounds is analyzed in a response surface technique using molecular connectivity indices to represent the molecular structure of the compounds. The response surface method is described and applied to this data set. The model uses the zero order chi indices, ⁰ χ and ⁰ χ ^v, as the variables in a general two-dimensional parabolic equation. The statistical results suggest a good model for estimation of BCF values:

The data set is analyzed further in terms of the sigma and delta chi zero indices: σ×0=⁰ χ + ⁰ χ ^v and Δ×0 = ⁰ χ - ⁰ χ ^v. These transformed chi indices are orthogonal and represent structure information in a useful manner. The Δ×0 index encodes molecular size and the Δ×0 index encodes electronic features related to pi and lone pair electrons. The structure information in the data set is analyzed in terms of these significant structure features. The data are presented in the form of a contour plot which facilitates analysis and indicates the maximum BCF for this data set.

Key Words:

• bioconcentration factor
• molecular connectivity indices
• nonlinear QSAR
• response surface