A technique for coating capillary columns with a very thick film of cross‐linked stationary phase

Abstract

SummaryA method for preparation of capillary columns and traps with a very thick film (up to 100 pm) of stationary phase is described. The principle of this method is based on an immediate fixation of a film of prepolymer, formed during dynamic coating. Thus, the development of film irregularities, such as are caused by Rayleigh instability i s avoided. Fixation of the film is conveniently accomplished by heat-accelerated crosslinking as was demonstrated in this work, where a commercially available silicone prepolymer (Sylgard 184, Dow Corning) was employed.The low phase ratio columns which thus can be prepared are interesting both in chromatography with dense mobile phases and as enrichment devices. Examples of the latter application are shown, where trace organic components from air and water were concentrated.

Improved thick film open tubular traps for the enrichment of volatile organic compounds from air and water

“…A decrease in film thickness of 3-6 % was noted after the first wash with pentane as was also observed earlier [8]. No further loss of stationary phase could be seen after an extended extraction with the different solvents.…”

“…Recently, we reported a new method for the preparation of very thick films (up to 100 pm) of cross-linked stationary phase in capillary tubes [8]. The technique is based on an instant film fixation at elevated temperature directly after a dynamic coating.…”

Ultra thick film open tubular traps with an increased inner diameter

“…The first trap (#1) was a borosilicate capillary, coated with a smooth, regular PDMS film, according to a process, described by Blomberg and Roeraade [6]. The second trap (#2, Silcosteel ® capillary tube, Restek Corp., USA) and the third trap (#3, borosilicate tubing), were coated with an irregular film of PDMS according to a new procedure.…”

“…A sorbent trapping technology, using capillary tubes, coated with an ultra thick film of stationary phase was introduced by us in the 1980s [5,6]. The extremely low phase ratio of such traps and the associated increase of the retention factor (k ) of analytes allows a quantitative enrichment of trace volatiles from considerable sample volumes.…”

Studies on the Use of Commercial Capillary Gas Chromatographic Columns as Diffusion Denuders

“…In recent years a few papers on the use of pieces of open tubular GC columns for isolation and enrichment of selected analytes from gaseous matrices [4,5,[8][9][10][11][12][13][14][15][16][17] and water [18][19][20][21][22][23][24][25] have been published. Open tubular GC columns have the structural features of a cylindrical denuder.…”