Paper-based colorimetric test strip for arsenic detection in vegetable oils

Arsenic, a potent carcinogen, easily accumulates in vegetable oils via contaminated raw materials and processing procedures, posing severe dietary health risks to humans. Current detection methods either rely on expensive instrumentation with complex operations or suffer from serious matrix interference in high-lipid oil samples. Herein, a paper-based colorimetric test strip was developed for rapid quantitative detection of inorganic arsenic in vegetable oils by modifying the classic Gutzeit method. After systematic optimization of the paper substrate, mercuric bromide concentration and dithiothreitol-assisted sample pretreatment, the strip achieved a limit of detection of 0.05 mg kg^-1 over a linear range of 0.05-1 mg kg^-1, with the whole analysis process completed within 30 min. Validation with spiked and real vegetable oil samples confirmed high consistency with ICP-MS results, with recoveries of 94.13-109.12%, and subsequent stability tests verified reliable performance after 28 days of storage at 4 °C, 37 °C and 45 °C, offering an efficient, low-cost on-site alternative for arsenic detection in vegetable oils and filling the gap in rapid grassroots screening.