Fabrication of a SnO2–graphene nanocomposite based electrode for sensitive monitoring of an anti-tuberculosis agent in human fluids

We demonstrated a simple and one step optimized preparation of a tin oxide–reduced graphene oxide (SnO2–Gr) nanocomposite through simultaneous oxidation and reduction of SnCl2 and graphene oxide (GO). The crystal structure, chemical composition, oxidation state, surface morphology and the average size of the SnO2 nanoparticles in the nanocomposite were discussed. The extent of defects present in the nanocomposite was calculated from the ID/IG ratio. Further, the electrochemical properties of the SnO2–Gr nanocomposite modified glassy carbon (SnO2–Gr/GC) electrode were studied by CV, which showed high electrocatalytic activity and enhanced electrochemical detection ability towards the anti-tuberculosis agent isoniazide (INH). The as fabricated SnO2–Gr/GC electrode reduces the overpotential of 610 mV when compared to the bare GC electrode. The potential of the optimized amperometric signal exhibited a linear relation with the concentration of INH in the range from 1.0 × 10−7 M to 8.5 × 10−4 M with a sensitivity of 0.0187 μA μM−1 and the limit of detection (LOD) was found to be 60 nM. The pulse optimized square wave voltammogram revealed a linear concentration range between 1.9 × 10−8 and 7.2 × 10−6 M with a high sensitivity of 1.098 μA μM−1 and the LOD was found to be 7 nM. Moreover, the SnO2–Gr/GC electrode was used to analyze INH in human urine samples and pharmaceutical tablets in the presence of coexisting interference substances; the SnO2–Gr/GC electrode also exhibited good repeatability, reproducibility and stability. The observed results confirm that the proposed sensor electrode was suitable for INH sensing.