Uniformly Sized Polymer Beads

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 resulting materials gave good efficiencies and worked well with microbore columns. An example of their use in the separation of some polyaromatic hydrocarbons is given in figure 55. The column was 15 cm long, 4.6 mm I.D. and the mobile phase 80%(v/v) aqueous acetonitrile employed at a flow rate of 1 ml/min. The temperature was 30°C and a UV detector operating at a wavelength 254 nm was used to monitor the separation. The performance of the polymer based packing was compared with that of a commercial silica based packing using a synthetic mixture. The chromatogram obtained for the mixture on the two columns is shown in figure 56.

1. Uracil	6. benzene
2. Caffeine	7. N,N-diethylaniline
3. 2-ethylpyridine	8. toluene
4.phenol	9. phenylacetyl acetone
5. butyl benzoate	10. naphthalene

0Column length 15 cm, diameter 2 mm, mobile phase 50% (v/v) aqueous acetonitrile, flow rate 0.19 ml/min., temperature 40°C, detector UV at 254 nm.

Figure 56 The Relative Performance of a Column Packed with Polymer Based Material to that from a Column Packed with Silica Based Material

It is seen that although the polymer columns exhibits a large number of theoretical plates and uracil and caffeine, and toluene and phenylacetyl acetone are better separated, 2-ethyl pyridine and phenol co-elute are also reasonably well resolved on the silica based column.