Abstract

A new sensitive and selective imprinted electrochemical sensor was developed for lorazepam determination, which is based on a pencil graphite electrode (PGE) modified with one-step electropolymerization of the molecularly imprinted polymer (MIP) composed from polypyrrole (ppy), sol-gel, gold nanoparticles (AuNPs), and lorazepam. AuNPs were introduced into the polymer composite for the development of electrical response by facilitating charge transfer of [Fe(CN)₆]^3-/[Fe(CN)₆]⁴⁻ which was used as an electrochemical active probe. The fabrication process of the sensor was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Several significant parameters controlling the performance of the MIP sensor were examined and optimized. Under the optimized condition calibration curve of the imprinted sensor has two linear concentration ranges from 0.2 to 2.0 nM and 2.0 to 20.0 nM, with the limit of detection (LOD) of 0.09 nM. The imprinted sensor has the advantages of high porous surface structure, ease of preparation, good reproducibility and repeatability, high selectivity and sensitivity. Furthermore, the proposed method was successfully intended for the determination of lorazepam in real samples (tablet, plasma, and urine).