Synthesis and Properties of Caffeine Molecularly Imprinted Polymers Based on Konjac Glucomannan

A novel molecularly imprinted polymers (MIPs) for caffeine based on konjac glucomannan (KGM) was prepared using grafted copolymer of KGM/acrylic acid as a functional monomer, N,N-methylenebisacrylamide as a cross-linker, and caffeine as a template. The recognition sites in MIPs were confirmed by Fourier transform infrared spectroscopy and the morphology of MIPs was characterized by scanning electron microscopy. Compared with nonimprinted polymers (NIPs), the obtained MIPs showed high adsorption capacity and good selectivity for caffeine. The maximum adsorption (Q(max)) of MIPs and NIPs for caffeine was 62.97 and 21.67 mg/g, respectively. The selective factor () of MIPs and NIPs was 2.50 and 0.91, respectively. Adsorption isotherm of MIPs followed the Langmuir equation. In addition, the obtained materials were packed on solid-phase extraction (SPE) cartridges and evaluated as a sorbent for selective trapping and preconcentration of caffeine from real beverage samples. Under the optimized extraction conditions, recoveries of caffeine ranging from 91.3 to 99.2% was achieved.