Determination of phenytoin in plasma by molecularly imprinted solid-phase extraction

A molecularly imprinted polymer (MIP) using phenytoin as template and metha crylamide as the functional monomer was prepared. The selectivity was measu red by comparing capacity factors of phenytoin and other structurally relat ed compounds. The polymer was evaluated as a selective sorbent in molecular ly imprinted solid-phase extraction (MISPE). Several washing solvents were tested to study their ability to disrupt the non-specific interactions occu rring between the sample and the polymer matrix and the role of water in th e recognition process was also investigated. It was shown that the key step of successful sample extraction is the right choice of the washing solvent . Plasma samples spiked with phenytoin were analyzed by the MISPE methodolo gy developed in this work. Method validation (intra- and inter-day precisio n, recovery, specificity) was carried out. The calibration curve showed goo d linearity in the 2.5-40 mug/ml range corresponding to therapeutically rel evant plasma levels. The intra- and inter-day precision values were below t he 15% limit established for bioanalytical methods. The results showed that the method could be successfully applied for the determination of phenytoi n in plasma samples. (C) 2001 Elsevier Science B.V. All rights reserved.