Conclusion

A novel AgNPs-ErGO-based electrochemical sensor was successfully developed using a one-step electrochemical synthesis strategy, enabling the in situ formation and direct deposition of the nanocomposite onto the GCE surface. The resulting material exhibited a well-defined nanostructure with uniformly dispersed AgNPs and strong synergistic effects between AgNPs and ErGO, leading to enhanced electrochemical performance.

The modified electrode exhibited a large electroactive surface area, fast electron-transfer kinetics, and excellent electrocatalytic activity toward sibutramine oxidation. The electrochemical process was identified as an irreversible reaction involving equal proton and electron transfer, governed by a mixed diffusion-adsorption mechanism.

The developed LSV method exhibited satisfactory analytical performance, including low detection limit, good linearity, high precision, and acceptable recovery. Importantly, the method was successfully applied to real samples, revealing the presence of illegally adulterated sibutramine in herbal products. The results were consistent with those obtained by HPLC-DAD, demonstrating the reliability and practical applicability of the proposed sensor.

Overall, this work highlights the strong potential of the AgNPs-ErGO/GCE sensor as a rapid, sensitive and cost-effective alternative for quality control and safety monitoring of pharmaceutical and functional food products.