Preparation of ordered macroporous molecularly imprinted polymers and their applications in purifying cinchona alkaloids from cinchona extract

Three-dimensionally ordered macroporous molecularly imprinted polymers (3DOM MIPs) were prepared for the direct purification of cinchona alkaloids from crude cinchona extract. The 3DOM MIPs were easily prepared by grafting quinine-MIPs on the pore walls of 3DOM thiol-group-functionalized silica. The materials were characterized using various techniques. The results showed that the 3DOM MIPs had a more regular macroporous structure, a greater surface area and a greater porosity than traditional bulk MIPs (TBMIPs). The 3DOM MIPs could reach a high MIP content of 69.9%. And the 3DOM structure could improve intraparticle adsorption and provide more accessible adsorption sites. Consequently, in both static adsorption experiments and solid-phase extraction (SPE), the actual adsorption capacity of the imprinted polymers of the 3DOM MIPs was about 83% higher than that of TBMIPs. Moreover, the 3DOM MIPs exhibited high affinity for quinine, quinidine and cinchonine. Using the quinine-3DOM MIPs as SPE sorbent, quinine, quinidine and cinchonine could be effectively purified from crude cinchona extract with high elution recoveries. Control experiments also showed that the 3DOM MIPs were superior to commercially available adsorbents in terms of the purification of cinchona alkaloids from crude extract. © 2021 Society of Chemical Industry