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

The solvation parameter model is used to study selectivity differences amon g five open tubular columns from different sources coated with an immobiliz ed poly(dimethyldiphenylsiloxane) stationary phase containing 5% diphenylsi loxane monomer groups. By regression analysis of the system constants and r etention factors it is demonstrated that all five columns possess similar s electivity with minor differences in their hydrogen-bond basicity over the temperature range 60 to 140 degreesC. Differences in selectivity between an arylene-siloxane copolymer with separation properties similar to the poly( dimethyldiphenylsiloxane) stationary phase are somewhat larger, with the co polymer stationary phase being less cohesive and more hydrogen-bond basic t han the poly(dimethyldiphenylsiloxane) stationary phases. A performance-det eriorated poly(dimethyldiphenylsiloxane) stationary phase is shown to be le ss cohesive, more hydrogen-bond basic and dipolar/polarizable than a perfor mance-acceptable column. The selectivity differences between the performanc e-acceptable and performance-deteriorated stationary phase are much larger than the difference between columns of a generic type.