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 analyzed by stepwise regression for their contribution to a linear regression model. A model was developed based on data for 400 chemicals and was verified 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 experimental Koc. The robustness of the model was validated by a modified jackknife test.