Synthesis and evaluation of polymer-based monolithic columns in capillary liquid chromatography

Abstract Monolithic poly (styrene-co-divinylbenzene) capillary columns were prepared by free radical cross-linking copolymerisation of styrene and divinylbenzene monomers in the presence of a mixture of tetrahydrofuran (THF) and 1-decanol as porogens inside a fused silica capillary of I.D 180 or 100 μm. The initiator, α,ά-azo-isobutyronitrile was used to initiate the chain reaction. The preparation of the monolithic column was carried out in three steps, pre-treatment, silanization and polymerisation according to a procedure described in the literature. The polymerization step was reinvestigated to get control over the production parameters. To obtain repeatable monolithic columns the amount of chemicals were weighed, and degassing of the polymerization solution with helium had to be avoided to prevent loss of chemicals. Parameters varied were the amount of 1-decanol, THF and divinylbenzene. The composition of the polymerization solution fond to be the best was as follows: 0.911 g divinylbenzene, 0.906 g styrene, 2.371 g 1-decanol, 0.356 g tetrahydrofuran and 40.0 mg (8 mg/ml) α,ά-azo-isobutyronitrile. The amount of 1-decanol was increased with 10%, relative to the amount described in the literature. The amount of the other chemicals in the polymerization solution was unchanged. By using this polymerization solution, columns which were repeatable with respect to efficiency and retention of proteins were produced. Efficiency testing of the columns was performed using a simple mixture of proteins, a mixture of cytochrome c, lysozyme and myoglobin (0.25 mg/mL of each)