Smartphone-based digital image colorimetry for rapid benzoyl peroxide detection in wheat flour

A rapid, portable, cost-effective colorimetric method was developed for detecting benzoyl peroxide (BPO) in wheat flour using a smartphone-based digital imaging system. Stable and consistent image acquisition was achieved using a custom-built, solar-powered lightbox. The method is based on the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) by BPO, producing a quantifiable color change. The analytical performance demonstrated a linear range of 2.89-40.0 mg/kg with a detection limit of 0.955 mg/kg. Accuracy was confirmed through recovery studies in spiked flour samples (100-102 %), and the method's trueness showed strong agreement with conventional high-performance liquid chromatography (HPLC). Furthermore, an AGREE evaluation score of 0.83 indicates a favorable alignment with green analytical chemistry principles, highlighting its improved sustainability profile over the reference HPLC method. This smartphone-based system offers an accessible and eco-friendly alternative to laboratory-bound techniques, presenting a valuable tool for on-site screening and food safety monitoring, particularly in resource-limited settings.