Cost-effective and novel Fe3O4-IL/CPE nanosensor for simultaneous electrochemical detection of theophylline and methyldopa drugs

Simultaneous determination of methyldopa (MD), and theophylline (THEO) drugs was developed by a modified carbon paste electrode (CPE) with magnetite iron oxide nanostructure and imidazolium ionic liquid (IL). The obtained results displayed that the Fe 3 O 4 -IL/CPE showed higher oxidation currents versus bare CPE and other modified electrodes. The pH 3.0 for PBS, temperature 34 °C, IL 5.0 %, and Fe 3 O 4 9.0 % in the fabricated sensor were developed as the maximum anodic currents. In the above optimal conditions, the linear responses with the DPV technique were attained in the 2.72–180.32 μM and 7.64–137.93 μM for MD and THEO, respectively. Also, the LOD of 0.90 and 2.52 μM were obtained for MD and THEO, respectively. We, also considered measurement of MD and THEO drugs in human plasma and mixtures of tablets as a real sample and the results show a good recovery percentage. • Synthesis and characterization of Fe 3 O 4 nanoparticle • Simultaneous quantification of Methyldopa and Theophylline by Fe 3 O 4 -IL/CPE nanosensor • Fe 3 O 4 -IL/CPE boosts sensor sensitivity vs. bare CPE. • Obtaining maximum current densities based on response surface methodology • Advantages of stability, repeatability and reproducibility of the nanosensor • Good capability of nanosensor for determination of MD and THEO in the human plasma