Potentiometric sensing of ibuprofen over ferric oxide doped chitosan grafted polypyrrole-based electrode

The present work demonstrates the correlation between structure, properties, and self-sensing protocols of in situ prepared ferric oxide doped grafted copolymer composite, comprised of ferric oxide, chitosan, and polypyrrole (α-Fe₂O₃-en-CHIT-g-PPy) for residual ibuprofen present in natural and artificial samples. The chemical structure, morphology, functionality, and physio-mechanical properties of the composite were determined by Fourier transform infrared spectrometer (FT-IR), Raman spectra, X-ray diffraction (XRD), Scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Two probe method, and standard ASTM techniques to explore sensing nature. The results confirm the evolution of axially aligned structure against 110 planes of α-Fe₂O₃ and chemically functionalized expanded polymer matrix during in-situ chemical polymerization of pyrrole, with better porosity, interactivity, and improved electrical conductivity i.e. 7.32 × 10^-3 S cm^-1. Further, a thin film of prepared composite coated on an ITO glass plate was explored for potentiometric sensing of ibuprofen (IBU) present in artificial and natural samples without the use of any additional energy sources. The observed sensing parameters are the sensing ranging 0.5 μM to 100.0 μM, sensitivity 2.5081 mV μM^-1 cm^-2, response time 50 s, recovery time 10 s, and stability for 60 days. The sensing mechanism of the IBU sensor and effective charge transfer in the electrode was also discussed based on changes in IR spectra of the electrode recorded before and after sensing due to surface oxidation of IBU due to the presence of iron and doping effect of iron oxide in the composite.