Abstract:

The relationship between the rule of chromatographic retention value and molecular structure is an important part in the research of chromatographic thermodynamics. The topological index structural parameter JG and the topological index adjoining parameter LJ are put forward. Parameter JG describes the correlation of quantity and position of chlorine atoms in polychlorinated biphenyl (PCB) molecules. Parameter LJ describes the ortho-position correlation of chlorine atoms in PCB molecules. The relational expression between the PCB molecular structures and their enthalpy change (ΔH), entropy change (ΔS′) in chromatographic process was discovered. The values of enthalpy change and entropy change for about 140 kinds of polychlorinated biphenyls in chromatographic process on three stationary phases, DB-1, DB-5 and DB-1701, were determined. In comparison with ΔH and ΔS′ of the experimental data those calculated from the relational expression had the average relative deviations for ΔH and ΔS′ are 0.56%-0.97% and 0.55%-1.06%, respectively.

Key words: chromatographic theory, enthalpy, entropy , molecular topology, chromatographic thermodynamics