Electroanalytical determination of quinine in biological samples using molecularly imprinted polymer-Au nanoparticles/MWCNT-chitosan pencil graphite electrode

Quinine is one of the naturally occurring alkaloids that derives from specified cinchonabarks. Electrochemical method has very advantages such as low detection limit, high precision and sensitivity, low cost, speed and portability. Molecularly imprinted polymers (MIPs) are from important materials that have been used for construction and modification of sensors. A selective and very sensitive sensor was developed to determine quinine based on new molecularly imprinted polymer (MIP). The sensor was constructed by coating of pencil graphite electrode (PGE) surface with a mixture of chitosan and functionalized multiwall carbon nanotube (MWCNT). Then, the electropolymerization of 3-methyl-4-nitrophenol was performed in acidic media and in presence of HAuCl4 solution to produce Au nanoparticles (AuNPs) together with MIP on the electrode surface. In this way, MIP-AuNPs/chitosan-MWCNT/PGE was constructed and applied to determine quinine. The signal reduction of the Fe2+as a probe in differential pulse voltammetric (DPV) technique versus quinine concentration was linear in the range of 0.1 pM to 1000 pM. This sensor was applied for determination of the quinine in the plasma and urine samples.