High-Efficiency Liquid Chromatographic Separation Utilizing Long Monolithic Silica Capillary Columns

Abstract

Long monolithic silica-C18 capillary columns of 100 microm i.d. were prepared, and the efficiency was examined using reversed-phase HPLC under a pressure of up to 47 MPa. At linear velocities of 1-2 mm/s, 100,000-500,000 theoretical plates could be generated with a single column (90-440 cm in length) using an acetonitrile-water (80/20) mobile phase with a column dead time (t0) of 5-40 min. It was possible to prepare columns with a minimum plate height of 8.5 +/- 0.5 microm and permeability of (1.45 +/- 0.09) x 10(-13) m(2). The chromatographic performance of a long octadecylsilylated monolithic silica capillary column was demonstrated by the high-efficiency separations of aromatic hydrocarbons, benzene derivatives, and a protein digest. The efficiency for a peptide was maintained for an injection of up to 0.5-2 ng. When three 100 microm i.d. columns were connected to form a 1130-1240 cm column system, 1,000,000 theoretical plates were generated for aromatic hydrocarbons with retention factors of up to 2.4 with a t0 of 150 min. The fact that very high efficiencies were obtained for the retained solutes suggests the practical utility of these long monolithic silica capillary columns.

Recent advances in preparation and application of hybrid organic‐silica monolithic capillary columns

“…As shown in Fig. 3, trialkoxysilanes with hydrophobic organic moieties, such as N-octadecyldimethyl [3-(trimethoxy silyl)propyl]ammonium chloride [23], n-octyltriethoxysilane (C8-TES) [32][33][34][35], phenyltriethoxysilane (PTES) [36][37][38], propyltrimethoxysilane (C3-TMS) [39], MTMS [40][41][42][43][44], and other trialkoxysilanes with active organic functionalities, such as aminopropyl triethoxysilane (APTES) [45][46][47][48][49], N-(␤-aminoethyl)-␥-aminopropyl-triethoxysilane [50], N-(␤-aminoethyl)-␥-aminopropylmethyldimethoxysilane [51], 3-chloropropyltrimethoxysilane [52], 3-mercaptopropyltrime thoxysilane (MPTMS) [53], N-trimethoxysilylpropyl-N,N,Ntrimethylammonium chloride [54], allyl-trimethoxysilane [ 55,56], and vinyltrimethoxysilane (VTMS) [57] have been selected as coprecursors with tetraalkoxysilanes, TMOS, or TEOS. Additionally, bridged silanes such as 1,4-bis(triethoxysily1)benzene [58] have also been used for preparation of hybrid monoliths.…”

Low-flow-resistance Methacrylate-based Polymer Monolithic Column Prepared by Low-conversion Ultraviolet Photopolymerization at Low Temperature

“…The low flow resistance allows the column length to be extended significantly. 17,18 Miyamoto et al demonstrated the separation of benzene and its deuterium substitutions using an octadecylsilyl (ODS)-modified silica monolithic column of 12.4 m in length. 17 Another unique application of monolithic columns was ultrahigh-speed separations using a mobile phase stream with a linear flow rate ranging from tens to one hundred mm s -1 .…”

“…17,18 Miyamoto et al demonstrated the separation of benzene and its deuterium substitutions using an octadecylsilyl (ODS)-modified silica monolithic column of 12.4 m in length. 17 Another unique application of monolithic columns was ultrahigh-speed separations using a mobile phase stream with a linear flow rate ranging from tens to one hundred mm s -1 . [19][20][21][22] Low-flow-resistance HPLC columns could be used to construct HPLC systems without the need for conventional LC high-pressure pumps to supply the mobile phase.…”

Two-Dimensional Protein Separation by the HPLC System with a Monolithic Column

“…Hence we developed an on-line, sequential, continuous 2D-HPLC system using an ionexchange (IEX) column in the first dimension and a reverse-phase (RP) monolithic column in the second. It demonstrated efficient protein separation at a high flow rate due to its permeability [8][9][10] (Fig. 1A).…”