Continuous-Bed Columns Containing Sol-Gel Bonded Packing Materials for Capillary Electrochromatography

Recent progress in capillary electrochromatography

“…In later work, Stol et al [47] also reported EOF transport on wide-pore silica particles. EOF transport through wide-pore silica particles entrapped in a capillary column by the sol-gel process has also been reported [49]. Flow through the pores in the particles is achieved by adjusting the concentration of electrolyte in the mobile phase, which in turn adjusts the thickness of the double layer inside the pore.…”

“…The second approach to entrap the chromatographic particles is by introducing the entrapping solution after the column has been packed [49,98,99,159]; the column is then dried, after which the temporary retaining frit (originally used to pack the column) is eliminated and the column cut to the desired length. The method by Remcho and Chirica [98] makes use of silicate sol solutions to fill the pressure-packed capillaries with subsequent heating.…”

“…The columns are then cured with 0.1 M ammonium hydroxide and dried at 160 o C to produce monolithic structures with reported efficiencies similar to those of packed columns, although with reduced retentive characteristics. Lee©s group [49,99,159], on the other hand, first packed the capillary using a CO 2 slurry packing method and then filled the capillary with a sol solution prepared with tetramethoxysilane and ethyltrimethylsilane. The column filled with the sol solution was dried using supercritical CO 2 for 5 h at 40 o C followed by further drying at 120 o C and 250 o C for the same amount of time.…”

Capillary Electrochromatography on Monolithic Silica Columns

“…A continuous-bed structure can be formed starting from a packed bed of silica particles in a capillary by bonding the particles together. [3][4][5][6][7] Such monolithic silica columns (20 -25 cm long) provided 40000 -70000 theoretical plates that were somewhat fewer than that of a column packed with particles without such a treatment. Monolithic columns based on organic polymers have been prepared from monomers in a capillary.…”

Capillary electrochromatographic study of sapphyrin-organophosphoric acid derivatives interaction

“…Generally three operation modes of this technique are in use [2]: (i) capillary electrochromatography with microparticulate sorbents (mostly C18 modified silica particles) packed capillaries [3][4][5] (ii) capillary electrochromatography using in situ polymerized (monolithic) packings [6][7][8][9][10][11][12] and (iii) open-tubular capillary electrochromatography [13]. The latter approach can be easily used with water-insoluble (poorly soluble) compounds, which can be bonded to the inner wall of the capillary simple by washing it with a solution of the modifier in an organic solvent (for review see [13]).…”