Hosoya et al. and Kobayashi et al. (17), developed a method for packing uniformly sized polymer based LC packing materials that provided practically adequate column efficiency using a copoly-merization technique. Figure 55 Chromatogram of Some Polyaromatic Hydrocarbons Separated on the Polymer Based Pickings The uniformly sized, polymer-based packing was prepared from mixtures of alkyl methracrylate and glycerol dimethacrylate by copolymerization techniques using a multistep swelling and polymerization method. The

separations appear to be based largely on exclusion. Macroporous Polymers such as the packings founded on the co-polymerization of polystyrene and divinylbenzene are also popular GC adsorbents. The extent of cross-linking determines its rigidity and the greater the cross-linking the harder the resin becomes until, at the extreme, the resin formed is very brittle. The macro-porous resin consists of resin particles a few microns in diameter, which in turn are composed of a fused mass of polymer micro-spheres, a few Angstroms in diameter. Consequently, the resin polymer has a relatively high surface area as well as high porosity. They exhibit strong dispersive type interaction with solvents and solutes with some polarizability arising from the aromatic nuclei in the polymer. Supports for GLC There have been a number of materials used as supports for packed GC columns including, Celite (a proprietary form of a diatomaceous earth), fire-brick (calcined

Initially, silicic acid is released,                            Na2SiO3 +H2O + 2HCl = Si(OH)4 + 2NaCl            However, the free acid quickly starts to condense with itself with the elimination of water to form dimers, trimers and eventually polymeric silicic acid. The Polymerization of Silicic Acid The polymer continues to grow, initially forming polymer aggregates and then polymer spheres, a few Angstrom in diameter. These polymeric spheres are called primary silica particles. The primary particles continue to grow until, at a particular size, the surface silanol groups (hydroxyl groups attached to the surface silicon atoms) on adjacent primary polymer particles, start condense. This condensation  causes the primary particles to adhere to one another and at this stage the solution begins to

special areas of application particularly in sample preparation. Macroporous Polymers Polymeric ion exchange materials were developed for chromatography in the early sixties resulting in the introduction of macro-porous polymers (29-31). The advantages of this material lay in the macro-porous nature of the resin packing, which consisted of resin particles a few microns in diameter, which, in turn, comprised of a fused mass of polymer micro-spheres a few Angstroms in diameter. The resin polymer micro-spheres play the same part as the silica gel primary particles, and confer on the polymer a relatively high surface area together with a high porosity. The high surface area provided increased solute retention and selectivity together with a superior loading capacity and, consequently, a wide dynamic range of analysis. The material consists of a highly cross-linked polystyrene resin with about a 50Å pore diameter. In the case of the ion exchange materials, inorganic groups of

Silica gel is manufactured by releasing silicic acid from a strong solution of sodium silicate by hydrochloric acid. (Sodium silicate is prepared by heating sand at a high temperature in contact with caustic soda or sodium carbonate). Initially, silicic acid is released,                   Na2SiO3 +H2O + 2HCl = Si(OH)4 + 2NaCl and then the free acid quickly starts to condense with itself with the elimination of water to form dimers, trimers and eventually polymeric silicic acid. The polymer grows, initially forming polymer aggregates and then polymer spheres, a few Angstrom in diameter. These polymeric spheres are called primary silica particles. These primary particles continue to grow until, at a particular size, the surface silanol groups on adjacent primary polymer particles, condense with the elimination of water. This condensation  causes the primary particles to adhere to one another and at this stage the solution begins to gel. During this process, the primary

a problem. The solute must be thermally stable so that the partial pressure is sufficiently high to allow elution in a reasonable time. Nothing can be done with respect to the solute stability as this is determined by the nature of the sample. There are certain materials hat can be used as stationary phases at remarkably high temperatures. These materials are based on the polymerization of carborane substituted siloxanes. An example of the empirical formula of a carborane silicone polymer is as follows,   where represents the meta–carborane nucleus. There are three commonly used carborane stationary phases, The first a dispersive phase, Dexsil 300 where the carboranes are linked with a methylsilicone polymer and can be used up to a temperature of 450˚C (an exceedingly high temperature for chromatographic separations). Some induced polarizability has been introduced into the carborane polymer by employing a methyl phenyl silicone and