Structures of 135 polychlorinated dibenzothiophenes (PCDTs) and 135 polychlorinated dibenzothiophene sulfones (PCDTO₂s) were characterized using electrotopological state index (ETSI) for atom types. Quantitative linear relationship models were built between gas chromatographic retention index (RI) from DB-5 GC column and ETSI descriptors were established for PCDT and PCDTO₂. The models derived from the variable selection and modeling based on prediction (VSMP) technique present correlation coefficient (r²) of 0.9939 for PCDT and of 0.9729 for PCDTO₂, leave-one-out cross-validation coefficient (q²) of 0.9921 for PCDT and of 0.9692 for PCDTO₂, respectively. In order to validate the stability and predictive power of the models, 17 PCDT and PCDTO₂ were used as training sets to build QSRR models. The models present r² of 0.9959 for PCDT and of 0.9783 for PCDTO₂, q² of 0.9921 for PCDT and of 0.9740 for PCDTO₂. The results demonstrate the robustness of the QSRR models. The models were used to predict the RI of test set with 8 compounds and predict set with 110 compounds, and the result of test set with 8 compounds show that the training set has a good predictive ability.

Key words: polychlorinated dibenzothiophene (PCDT), polychlorinated dibenzothiophene sulfone (PCDTO₂), quantitative structure-retention relationship (QSRR), electrotopological state index (ETSI)