Smartphone-Based Digital Image Analysis (DIA) for Rapid Determination of Pyraclostrobin in Water and Vegetable Samples

Abstract

An efficient and user-friendly smartphone-based digital image analysis (DIA) method was developed for the determination of pyraclostrobin residues in water and vegetable samples. The proposed method is based on a diazotization–coupling reaction, in which pyraclostrobin has been converted into a stable azo dye, enabling quantitative analysis by both conventional UV–Vis spectrophotometry and smartphone-assisted DIA. The developed approach offers a practical alternative for rapid pesticide residue screening, particularly for field-based and resource-limited applications. The analytical performance of both methods was systematically evaluated in terms of linearity, limit of detection (LOD), limit of quantification (LOQ), precision, and recovery. The UV–Vis spectrophotometric method showed a linear response over the concentration range of 0.21–1.00 mg L⁻1, with LOD and LOQ values of 0.06 and 0.21 mg L⁻1, respectively, and excellent repeatability with a minimum %RSD of 0.93%. The smartphone-based DIA method, using the green (G) color channel for quantification, achieved LOD and LOQ values of 0.09 and 0.32 mg L⁻1, respectively, with satisfactory precision (%RSD = 2.88%). The applicability of the proposed methods was validated using real samples, including surface water, tap water, drinking water, and vegetable matrices. Recovery values ranged from 86.0 to 104.0% for the UV–Vis method and 95.0–120.0% for the smartphone-based DIA method. These results demonstrate that the proposed smartphone-assisted DIA method provides a reliable, portable, cost effective and accessible platform for rapid pyraclostrobin residue primary screening in environmental and food samples, showing strong potential for on-site monitoring and food safety applications. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2026.