A cost-effective, sensitive and disposable modified pencil graphite electrode decorated with layers of AgNPs and poly(L-cysteine) for the detection of pyrimethanil fungicide

Abstract

Pyrimethanil [PMT] is one of the most preferred fungicides for controlling grey mould, wilt, leaf scab, and blight diseases in fruits and vegetables. A disposable, inexpensive, simple, and sensitive modified silver nanoparticles/poly-L-cysteine pencil graphite electrode [AgNPs/poly(L-cys)/PGE] was developed using an electrodeposition technique to study the electrochemical behaviour and determination of the PMT in pH 4.0 phosphate-citric acid buffer solution. The surface morphology and surface area of the sensor were elucidated using scanning electron microscope [SEM] and cyclic voltammetry [CV], respectively. To study the electrochemical behaviour and quantitative determination of PMT by square wave voltammetry [SWV] on AgNP/poly(L-cys)/PGE, parameters such as pH, frequency, step potential, and pulse amplitude, which have significant effects on the current and potential, were optimised separately at first time. Under optimum experimental conditions, the linear dynamic range [LDR] was 20.0-500.0 mu g/L, and the limit of detection [LOD] and limit of quantification [LOQ] values were highly sensitive at 20.24 mu g/L and 67.47 mu g/L, respectively. Additionally, the interference effects of some pesticides were studied, and PMT was analysed with high recovery and low relative error. Finally, the analytical application of the proposed method and modified AgNPs/poly(L-cys)/PGE was successfully demonstrated in real samples, such as the commercial drug Mythos((R)) and tap water. Accordingly, 3.0 mu M PMT prepared from MYTHOS (R) drug was found to be 2.98 +/- 0.03 mu M at 95% confidence level (n = 3) and was determined with 99.56% recovery, 0.39% relative standard deviation and - 0.43% relative error. Ultimately, a fully validated, simple, inexpensive, sensitive, reproducible, environmentally friendly, miniature, and disposable nanosensor for the determination of PMT was developed.