Molecularly imprinted solid phase extraction micro-column with differential pulsed elution for theophylline determination

The technique of molecular imprinting is used to produce an extensively cro ss-linked poly(methacrylic acid-co-ethylene dimethacrylate) material that c ontains theophylline as a print molecule. After Soxhlet extraction of the t heophylline, binding sites are formed in the polymer with complementary siz e, shape, and positioning of chemical functionalities for high theophylline selectivity. The molecularly imprinted polymer has good binding capacity, chemical stability, and physical robustness properties which make it an ide al packing material for micro-columns used in solid phase extraction. Pulse d elution of the bound theophylline can be accomplished through injection o f 20 mu l of methanol, which has the proper polarity and protic nature to d isrupt the hydrogen bonding and electrostatic interactions between basic th eophylline molecules and acidic binding sites. Nonspecific adsorption of in terfering drugs can be eliminated by a novel differential pulsed elution, w ithout sacrificing the selective binding of theophylline. This novel microa nalysis technique, MISPE-DPE, offers the advantage of micro-scale performan ce for sample introduction, chemical interference removal, and spectrometri c theophylline determination over a linear dynamic range of 1-100 mu g/ml. (C) 1999 Academic Press.