High performance liquid chromatography support particles

SynChropak GPC supports were introduced in 1978 as the first commercial columns for high-performance liquid chromatography of proteins. SynChropak GPC columns were based on research developed by Fred Regnier and coworkers in 1976 (1,2). The first columns were only available in 10-yu,m particles with a 100-A pore diameter, but as silica technology advanced, the range of available pore diameters increased and 5-yu,m particle diameters became available. SynChropak GPC and CATSEC occasionally were prepared on larger particles on a custom basis, but generally these products have been intended for analytical applications. 

Suspensions of these spherical particles are used for spray drying to produce large agglomerates which are used as packings for various separation techniques such as High Performance Liquid Chromatography (HPLC) or Supercritical Fluid Chromatography (SFC). They also serve as supports for catalysts. 

High-performance liquid chromatography does similar things with more sophisticated instrumentation. It can separate closely related chemical compounds on a research scale or on a preparative scale liquid solvents, or mixtures of several solvents under positive pressure, replace the "carrier gas" of Fig. 11.3. The solid support must have small particle sizes (3- to 10-pm diameter), so that relatively high pressures can be sustained throughout the column, and it is at the interface between the liquid eluant and the solid particles that the chromatographic separation is accomplished. 

There are a variety of HPLC columns and most of them are based on silica particles. The most popular column used today is the reversed-phase Cl8 column that uses a silica support with a bonded organic surface layer. Traditional HPLC analytical columns are usually 4.6 mm x 250 mm with a 5 pm particle size, as used in the USP official method. Modern columns for HPLC-mass spectrometry (LC-MS) applications are more efficient and offer the same or better resolving power in a much smaller package (2.1 mm x 150 mm with a 3.5 pm particle size or smaller). Ultra high-performance liquid chromatography (UHPLC) columns (sub 2pm particle size, 1-2 mm in diameter and 30-100 mm in length) are becoming more and more popular. 

Immunoaffinity extraction is a technique often adopted in clinical chemistry. Immu-noaffinity supports contained polyclonal antibodies covalently immobilized on sephar-ose, agarose, or silica supports. Two different kinds of supports, crushed sol-gel monoliths and sol-gel-coated highly porous silica particles, were applied to the extraction of 16 sulfonylureas in food and natural water followed by high-performance liquid chromatography-ultraviolet/diode-array detection (LC-UV/DAD) [32]. 

High-performance liquid chromatography, referred to as HPLC, uses partitioning to separate and identify the components in a mixture. The stationary phase is a nonvolatile liquid, such as a long-chain hydrocarbon liquid, bonded onto a solid support, e.g. small particles of silica. This is packed tightly into a column. The solvent chosen for the mobile phase is usually polar, e.g. a methanol/water solvent. This has to be forced under pressure through the densely packed column where separation occurs (Figure 29.8). 

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