An Electrochemical Sensing Platform Based on a Carbon Paste Electrode Modified with a Graphene Oxide/TiO2 Nanocomposite for Atenolol Determination

Atenolol is a medication belonging to the class of drugs known as beta-blockers, used to treat high blood pressure (hypertension) and irregular heartbeats (arrhythmia). Their presence in the environment has serious impacts on humans, animals, and the water ecosystem. In this context, the aim of this study was to develop a simple voltammetric method for the determination of atenolol (ATN) using carbon paste electrodes modified with the nanomaterials TiO2 and rGO/TiO2. The analytical performance of the modified sensor was evaluated using square wave voltammetry and cyclic voltammetry in 0.1 mol L−1 acid sulfuric solution (H2SO4), pH 2. The nanocomposite electrode CPE/rGO/TiO2 exhibited excellent electrocatalytic activity towards ATN oxidations at 0.1 mol L−1 H2SO4 compared with unmodified carbon paste electrodes CPEs and those modified with titanium oxide, CPE/TiO2. Different experimental and conditional parameters were optimized, such as supporting electrolytes, pH, amplitude, frequency, etc. Under optimal conditions, linear calibration curves were obtained, ranging from 1.7 to 23.2 µmol L−1 for ATN with detection limits of 0.05 μmol L−1. The modified nanocomposite CPE/rGO/TiO2 sensor showed good sensitivity and good repeatability (RSD ≤ 0.61%) for ATN determination. The proposed sensor is mechanically robust and presented reproducible results and a long useful life. In order to verify the usefulness of the developed methods, the nanocomposite sensor CPE/rGO/TiO2 was applied for the detection of atenolol in real samples (pharmaceutical tablets without any pre-treatment). The excipients present in the tablets did not interfere in the assay. Recoveries ranging from 97.7% to 106% were obtained. The results showed that the CPE/rGO/TiO2 voltammetric sensor could be successfully applied in the routine quality control of ATN in complex matrices.