Pencil graphite electrode modified with nitrogen-doped graphene and molecular imprinted polyacrylamide/sol-gel as an ultrasensitive electrochemical sensor for the determination of fexofenadine in biological media

Abstract

A sensitive and selective sensor was developed for the determination of fexofenadine (FEX) drug. The sensor was constructed based on the modification of a pencil graphite electrode (PGE) as a low cost, high available and versatile working electrode. The PGE was modified by nitrogen-doped graphene (NDG) and molecularly imprinted polymer (MIP) as receptor to increase the sensitivity and reducing the interference of other chemicals. NDG was electrochemically deposited on the electrode surface which is more homogeneous and facilitated than its conventional chemical synthesis. The molecular imprinted polymer was immobilized on the NDG layer by the sol-gel technique. In the optimum conditions, the imprinting factor was obtained equal to 4.8, indicating the optimal selectivity of the sensor for the determination of FEX. Differential pulse voltammetry (DPV) was used for the determination of FEX, which exhibited a linear calibration graph of Ip versus FEX concentration in the range of 5.0 × 10−10-7.8 × 10-6 M (mol L-1). The detection limit of the sensor was calculated equal to 1.5 × 10−10 M, which displayed a superior detection limit when compared with the other electrochemical sensors reported for the FEX determination. The developed sensor contained advantages of simple design, satisfactory reproducibility, appropriate determination recoveries and high selectivity. These features permitted the successful application of the sensor for the measurement of FEX in pharmaceutical and biological samples.