Synthesis of mixed-functional-phase silica supports for liquid chromatography and their applications to assays of drugs in serum.

Mixed-functional-phase (MFP) silica supports were designed for the direct injection determination of drugs in serum. The MFP silicas were synthesized from porous silica materials in three or four steps: introduction of 3-glycidoxypropyl phases, introduction of phenyl, butyl or octyl phases and hydrolysis of the oxirane ring to diol phases, or these three steps plus further introduction of glycerylpropyl (i.e., diol) phases. Although the further introduction of glycerylpropyl phases resulted in a reduction in the column efficiency, serum proteins were completely recovered in the first injection of serum samples. The prepared MFP packing materials can be used for the direct injection determination of hydrophobic and hydrophilic drugs in serum.