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

Abstract

Molecular imprinting of theophylline in poly(methacrylic acid ethylene dimethacrylate) form binding sites with complementary size, shape and chemical functionalities to theophylline. This molecularly imprinted polymer (MIP) can be packed into a micro-column for selective solid phase extraction (SPE) of theophylline from 20 microl of sample solution. Its chemical inertness and thermal stability allow the use of various organic solvents and elevated column temperatures for effective binding of theophylline. Non-specific adsorption of interfering drugs on the MIP surface is eliminated by an intermediate wash with 20 microl of acetonitrile, prior to quantitative desorption of the bound theophylline by 20 microl of methanol for in-line UV spectrophotometric determination. In this differential pulsed elution (DPE) technique, both the column temperature and solvent flow rate can be optimized to enhance selectivity. Application of this micro-analytical method, molecularly imprinted solid phase extraction DPE (MISPE-DPE), is demonstrated for accurate determination of theophylline in human blood serum. The method is validated over a linear range from 2 microg/ml to at least 20 microg/ml.