Static coating of 5 to 50 μm I.D. capillary columns for open tubular column chromatography

Dichlorofluoromethane, trichlorofluoromethane and tetramethylsilane were used in the static coating of small diameter capillary columns (5 to 50 μm I.D.) in order to obtain highly efficient columns for gas and supercritical fluid chromatography. Capillary columns of 5-, 10-, 25-, and 50-μm I.D. were coated with stationary phase films of SE-33, SE-54, OV-215, 50% n-octyl, 45% phenoxypolyethyl ether, 50% liquid crystal, 25% biphenyl, 50% pentafluorophenyl and 50% cyanopropyl polysiloxane stationary phases. Resultant evaluations of these columns in gas chromatography gave approximately 9000, 66 000, 45 000, and 19 000 plates m−1, respectively, for the different internal diameters. Important parameters which affect coating efficiency are identified and discussed in detail.