Using partial least-squares (PLS) regression and electrotopological state indices (ESI), two quantitative structure-property relationship models on photolysis half-lives (t_1/2) of polychlorinated dibenzofurans (PCDFs) on spruce (Picea abies) needles and fly ash surfaces were developed. For the optimal quantitative structure-property relationship (QSPR) models, the cross validated coefficients Q_cum² were 0.758 and 0.701, the standard deviation values were 0.047 and 0.049 respectively. The QSPR models have great robustness and good predictive abilities. The results show that the stability of the PCDF molecules increases with the increasing of chlorine atoms in the parent molecules, which may be a result of steric hindrance and low electron density on phenyl rings of highly chlorinated PCDFs.

Key words: electrotopological state, polychlorinated dibenzofuran, QSPR