Preparation of monodisperse porous poly(glycidylmethacrylate-co-ethylenedimethacrylate) microspheres and their application as stationary phase for superheated water HPLC.

Monodisperse porous poly(glycidylmethacrylate-co-ethylenedimethacrylate) (poly(GMA-co-EDMA) beads) with a diameter of 3μm each were custom synthesized by a single-step swelling and polymerization method. Small sizes (1.2μm) with polystyrene seed templates of low molecular weight were prepared by the addition of 1,1-diphenylethylene to control the polymerization reaction. Polystyrene seed particles were swollen directly by a mixture of methacrylate monomers and porogen. By swelling polystyrene seed particles with tetrahydrofuran as the porogen, a surface area of 108m(2)g(-1) was achieved. The porous polymer microspheres were evaluated as stationary phase for liquid chromatography using superheated water as a mobile phase. Chromatographic performance at different temperatures was studied, along with analyte and column stability. The results confirm that the particles were stable under superheated water conditions. There was almost no change to the retention properties during the 160 sequential injections of a standard mixture (uracil, pyridine, phenol, dimethyl phthalate and N,N-dimethylaniline) at 150°C. The chromatographic peaks show good symmetry with an efficiency of up to 47,000 platesm(-1) under realistic separation conditions. Thermal decomposition of analytes (aldicarb sulfone, oxamyl, aldicarb and benomyl) separated under different column temperatures, was evaluate. Chromatograms of pesticide standard mixtures separated in the temperature range of 100-140°C displayed good separation. The detection limits of 1.2 and 1.6mg L(-1) for benomyl and aldicarb were obtained when the separation was performed at 120°C with flow rate of 0.4mL min(-1) water. However these pesticides were decomposed at the separation temperature above 140°C.