Synthesis of polymer-coated mixed-functional packing materials for direct analysis of drug-containing serum and plasma by high-performance liquid chromatography.

Silicone polymer-coated mixed-functional (PCMF) silica packing materials were developed for the direct determination of drugs contained in serum or plasma. The new stationary phases were prepared by the following three-step procedure: (1) coating porous silica with a silicone polymer; (2) partial introduction of hydrophobic groups; and (3) introduction of hydrophilic groups. Two PCMFs were synthesized, one having polyoxyethylene groups as hydrophilic groups (PCMF-POE) and the other having oligoglyceryl groups (PCMF-OG). PCMF-POE showed higher recoveries for injected proteins and a greater overall retention for drug molecules than PCMF-OG. PCMF-POE did not show any column deterioration in 500 serum sample injections (10 ml in total).