Synthesis and sorptive properties of molecularly imprinted polymer for simultaneous isolation of catecholamines and their metabolites from biological fluids

Simultaneous quantitative analysis of catecholamines (CAs) and their respective acid metabolites in biological fluids can become a powerful tool for diagnosis and treatment of various diseases. However, selective sample preparation procedure is necessary to isolate the aforementioned analytes from the matrix. Therefore, we propose a synthetic strategy for the preparation of a molecularly imprinted sorbent with binding sites for both CAs and their respective acid metabolites. The synthesis combines noncovalent and semicovalent imprinting methods. Methylenebisacrylamide, 4-vynilbenzyl-N,N,N-trimethylammonium (3,4-dimethoxyphenyl)acetate, and 3-phenylpropylacrylate were used as the cross-linker, functional monomer 1/“dummy” template 1, and functional monomer 2/“dummy” template 2 under precipitation polymerization conditions, respectively. The polymer was characterized using Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy. The binding properties were studied by constructing adsorption isotherms and conducting competitive binding tests. The performance of the molecularly imprinted polymers (MIPs) toward CAs and the acids was described by good imprinting factors (3.1–5.6), fast-binding equilibrium, and the ability to differentiate nonmethylated CAs from methylated ones. The MIP was used to simultaneously isolate the analytes from human plasma under dispersive solid-phase extraction conditions with subsequent detection using optimized UHPLC/MS/MS procedure. As a result, no major interferences were detected which suggests that the impurities were well separated from the analytes.