STUDY OF POLYORGANOSILOXANES (NATIVE AND SOLVENT SWOLLEN) FOR THE PREPARATION OF NARROW (5-15 MU-M ID) AND LONG (1-6 M) OPEN-TUBULAR COLUMNS IN REVERSED-PHASE LIQUID-CHROMATOGRAPHY

Narrow-bore, (5-15 mum), long (up to 6 m), efficient and stable open tubular columns with four different polyorganosiloxane coatings, were prepared by the static coating and the precipitation coating methods. The polysiloxanes were substituted with phenyl- (OV-17-vi and PS-264), methyl- (PS-255), and octadecyl- (PMSC18) groups. They were studied in their regular cross-linked state as well as after swelling with n-heptane. Anthracene derivatives were used as model compounds. Column properties such as retention, selectivity and efficiency were investigated in reversed-phase liquid chromatography. GC was used for complementary studies of 50 mum I.D. columns. The highest retention was obtained on the columns coated with OV-17-vi and on the swelled stationary phases. A considerable resolution improvement was obtained in the columns, after swelling with n-heptane owing to the increase in retention. More than 10(6) theoretical plates were achieved in 70 min at a k' of 0.46 in a 6 m x 6 mum I.D. column.