Green voltammetric determination of the fungicide Fluopyram using a single-use pencil graphite electrode: Application to juice and urine samples

Abstract

Fluopyram, a broad-spectrum fungicide extensively used in agricultural systems to protect crops against a wide range of fungal pathogens, has raised increasing concern due to its potential persistence and accumulation in food and biological systems. Therefore, the development of simple, cost-effective, and highly sensitive detection strategies for monitoring Fluopyram residues is of considerable importance. In this study, we systematically explored the electrochemical properties and detection capability of Fluopyram using cyclic voltammetry (CV) and square-wave voltammetry (SWV) with a single-use pencil graphite electrode serving as the disposable working electrode. The CV measurements demonstrated that Fluopyram undergoes an irreversible oxidation process, yielding a well-defined anodic peak at approximately +1.05 V in a 0.04 M Britton–Robinson buffer solution at pH 4.0, which reflects a diffusion-controlled electron transfer mechanism. Quantification studies carried out with SWV revealed an excellent linear response over a wide concentration range from 0.04 to 1.23 μg/mL (R² > 0.99). Notably, the method achieved a very low limit of detection of 0.009 μg/mL, underscoring the superior sensitivity of the proposed electroanalytical approach compared to many conventional methods. To evaluate its real-world applicability, the method was successfully applied to spiked urine and orange juice samples, where satisfactory recovery values confirmed its robustness in complex matrices. The electrochemical results were further validated by comparison with spectrophotometric measurements, demonstrating good consistency between the two techniques. Overall, this work introduces a disposable, rapid, and reliable electroanalytical platform for Fluopyram determination, offering promising potential for environmental monitoring, food safety assessment, and clinical applications.