Miniaturized molecularly imprinted polymer extraction method for the gas chromatographic analysis of flavonoids

In this study, the use of monolithic molecularly imprinted polymers in a micropipette tip format allowing the simple and fast extraction of flavonoids from standard solutions and a black tea sample is demonstrated. The imprinted polymer employed quercetin, methacrylic acid or 4-vinylpyridine, and ethylene glycol dimethacrylate as template, functional monomer, and cross-linker, respectively. Surface morphologies of the quercetin-imprinted polymers and the corresponding nonimprinted polymers were characterized by SEM. Extraction of flavonoid standards was performed to evaluate the selectivity and recovery with these imprinted and nonimprinted polymers. Flavonoid compositions in aliquots eluted from the tips were identified using fast GC with flame ionization detection. Maximum specific capacities of 0.2, 5.7, and 16.0 mg/g for catechin, morin, and quercetin, respectively, were obtained with the imprinted polymer prepared with methacrylic acid, with the corresponding recoveries of 99.8, 98.8, and 95.4%, respectively. Efficient extraction by the quercetin-imprinted polymer of epicatechin, catechin, and quercetin from an apple-flavored black tea sample was achieved, with GC-MS employed for compound identification for both the tea and extracted samples.