Rapid determination of theophylline in serum by selective extraction usinga heated molecularly imprinted polymer micro-column with differential pulsed elution

Molecular imprinting of theophylline in poly(methacrylic acid-ethylene dime thacrylate) form binding sites with complementary size, shape and chemical functionalities to theophylline. This molecularly imprinted polymer (MIP) c an be packed into a micro-column for selective solid phase extraction (SPE) of theophylline from 20 mu l of sample solution. Its chemical inertness an d thermal stability allow the use of various organic solvents and elevated column temperatures for effective binding of theophylline. Non-specific ads orption of interfering drugs on the MIP surface is eliminated by an interme diate wash with 20 mu l of acetonitrile, prior to quantitative desorption o f the bound theophylline by 20 mu l of methanol for in-line UV spectrophoto metric determination. In this differential pulsed elution (DPE) technique, both the column temperature and solvent flow rate can be optimized to enhan ce selectivity. Application of this micro-analytical method, molecularly im printed solid phase extraction-DPE (MISPE-DPE), is demonstrated for accurat e determination of theophylline in human blood serum. The method is validat ed over a linear range from 2 mu g/ml to at least 20 mu g/ml. (C) 1999 Else vier Science B.V. All rights reserved.