Semi-micro-monolithic columns using macroporous silica rods with improved performance

Efficiency of short, small-diameter columns for reversed-phase liquid chromatography under practical operating conditions

“…They were packed with (1) Kinetex C18, 2.6 m core-shell particles (Phenomenex, Torrance, CA, USA), (2) InertSustain C18, 2 m particles (GL Sciences), and (3) glass-clad monolithic silica column modified with dimethyloctadecylsilyl moieties (MonoTower, GL Sciences). The monolithic silica was prepared and glass-clad according to the procedure described previously [25]. Two columns were supplied for each particulate packing material which showed very similar results in a preliminary test.…”

Core–Shell, Ultrasmall Particles, Monoliths, and Other Support Materials in High-Performance Liquid Chromatography

“…Hara successfully improved the column efficiency of silica monolith in a capillary by increasing the silane content relative to the aqueous portion in the preparation feed to reduce the porosity or to increase the phase ratio, and increasing the PEG content to retard phase separation, in turn to reduce the domain size 113 Nakanishi and coworkers prepared silica monoliths using TEOS and nitric acid in the presence of poly(acrylic acid) (PAA) instead of TMOS, acetic acid, and PEG, and clad the silica rod with silicate glass 114 . The glass-clad silica rod, 2.4 mmID, 9 cm, produced H= 6.9 m.…”

Monolithic silica rod columns for high-efficiency reversed-phase liquid chromatography

“…Although it has been shown to be possible to connect the rod-type monolithic silica columns to form a long column system to achieve high-efficiency separations, a considerable decrease in column performance was observed for the connected columns [8]. These considerations prompted the development of another method of preparation of monolithic silica columns, different from that of Chromolith [21]. We report here the properties of monolithic silica rod columns of up to 25 cm in length that can provide higher column efficiency per unit time and column length than currently available rod-type monolithic silica columns, and a brief comparison of the performance with a column packed with superficially porous particles of 2.6 or 2.7 m diameters.…”

“…Those prepared from TMOS or hybrid columns prepared from a mixture of TMOS and methyltrimethoxysilane in the presence of polyethylene glycol were able to show a plate height of 5-5.5 m, roughly equivalent to a column packed with 2.5 m particles, with back pressure equivalent to a column packed with 5 m particles. Improvement of a preparation method aiming at higher column efficiency per unit time is also of much interest for rod-type columns [20][21][22]. In addition, it was thought to be desirable to provide longer monolithic silica rod columns than those currently available to generate greater numbers of theoretical plates with conventional HPLC equipment.…”