Selectivity equivalence of poly(dimethyldiphenylsiloxane) stationary phases for open-tubular column gas chromatography

The solvation parameter model is used to study selectivity differences among five open tubular columns from different sources coated with an immobilized poly(dimethyldiphenylsiloxane) stationary phase containing 5% diphenylsiloxane monomer groups. By regression analysis of the system constants and retention factors it is demonstrated that all five columns possess similar selectivity with minor differences in their hydrogen-bond basicity over the temperature range 60 to 140°C. Differences in selectivity between an arylene-siloxane copolymer with separation properties similar to the poly(dimethyldiphenylsiloxane) stationary phase are somewhat larger, with the copolymer stationary phase being less cohesive and more hydrogen-bond basic than the poly(dimethyldiphenylsiloxane) stationary phases. A performance-deteriorated poly(dimethyldiphenylsiloxane) stationary phase is shown to be less cohesive, more hydrogen-bond basic and dipolar/polarizable than a performance-acceptable column. The selectivity differences between the performance-acceptable and performance-deteriorated stationary phase are much larger than the difference between columns of a generic type.