Gadolinium oxide modified molecular imprinted polymer electrode for the electrochemical detection of theophylline in black tea

The present study reported a facile approach to fabricate a molecular imprinted polymer electrode modified with nano-composites of gadolinium oxide (Gd₂O₃@TH-MIP-CPE) to detect theophylline in variants of black tea samples. The synthesized electrode material was characterized by scanning electron microscope, fourier transform infrared spectroscopy and UV–visible spectroscopy. The electroanalytic performance of the Gd₂O₃@TH-MIP-CPE electrode was studied using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The electrode exhibits a linear response from 50 µM to 900 µM with limit of detection being 2.004 µM. The electrode showed significant repeatability (%RSD=1.19), reproducibility (%RSD=0.92) and stability (%RSD=1.015_). To evaluate the predictive ability of the electrode, partial least square regression (PLSR) model has been developed by correlating the high-performance liquid chromatography (HPLC) values with the voltammogram signals recorded using the electrode. The average prediction accuracy obtained from the PLSR model is 91.3 % with root mean square error of calibration being as low as 0.73.