Estimation of organic carbon normalized sorption coefficient (Koc) for soils by topological indices and polarity factors'

The relationship between topological indices and sorption coefficients (Koc ) based on 543 chemicals was investigated The range of the experimental Koc values covered 6.4 log-units. Polarity correction factors were introduced. The molecular connectivity indices and polarity correction factors were an alyzed by stepwise regression for their contribution to a linear regression model. ii model was developed based on data for 400 chemicals and was veri fied using a testing set including another 143 chemicals. The mean residual was 0.346 log-units for the model and 0.253 log-units for overlapping expe rimental Koc. The robustness of the model was validated by a modified jackk nife test. (C) 1999 Elsevier Science Ltd. All rights reserved.