Facile synthesis of molecularly imprinted polymers for selective extraction of tyrosine metabolites in human urine.

In this study a method is developed for quantitative analysis of three potential biomarkers, including 4-hydroxyphenyl acetic acid (PHPAA), 4-hydroxyphenyl lactic acid (PHPLA) and 3,4-hydroxyphenylpropionic acid (PHPA), in human urine. Molecular imprinted polymers (MIPs) as the sample clean up materials were applied to selectively extract these tyrosine metabolites, followed by precise detection using ultra-high performance liquid chromatography coupled with a fluorescence detector (UHPLC-FLD). The MIP was prepared by precipitation polymerization adopting PHPAA as the template molecule, 1-vinylimidazole (1-vinyl) as functional monomer, trimethylolpropane triacrylate (TRIM) as crosslinker, 2-methylpropionitrile (AIBN) as initiator and acetonitrile as a porogen. The molecular recognition properties and selectivity of MIPs were systematically evaluated, of which results demonstrated high selectivity for three analytes in human urine. Parameters affecting the extraction efficiency were further optimized. Under the optimum conditions, the limits of detection of PHPAA, PHPLA, and PHPA were 1.8 × 10-4, 4.7 × 10-5 and 5.8 × 10-5 mmol L-1, respectively, and the recoveries were in the range of 75.7%-110.3%. The method described here provided insights into the future development of materials for highly efficient and selective enrichment of targeted substances.