Enhanced electrocatalytic oxidation of isoniazid at electrochemically modified rhodium electrode for biological and pharmaceutical analysis

• Sensitive electrochemical method was proposed for INZ detection at Rh/GCE.
• The proposed electrode has been characterized by FE-SEM, SEM and EIS analysis.
• An enhanced and good oxidation behavior was observed for INZ at Rh/GCE.
• Wide linearity of 70–1300 μM obtained and best in present reported methods so far.
• Practicality, applicability proved in plasma, urine and pharmaceutical samples.

A simple and sensitive electrochemical method has been proposed for the determination of isoniazid (INZ). For the first time, rhodium (Rh) modified glassy carbon electrode (GCE) has been employed for the determination of INZ by linear sweep voltammetry technique (LSV). Compared with the unmodified electrode, the proposed Rh modified electrode provides strong electrocatalytic activity toward INZ with significant enhancement in the anodic peak current. Scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM) results reveal the morphology of Rh particles. With the advantages of wide linearity (70–1300 μM), good sensitivity (0.139 μA μM−1 cm−2) and low detection limit (13 μM), this proposed sensor holds great potential for the determination of INZ in real samples. The practicality of the proposed electrode for the detection of INZ in human urine and blood plasma samples has been successfully demonstrated using LSV technique. Through the determination of INZ in commercially available pharmaceutical tablets, the practical applicability of the proposed method has been validated. The recovery results are found to be in good agreement with the labeled amounts of INZ in tablets, thus showing its great potential for use in clinical and pharmaceutical analysis.

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