A quinoline colorimetric ionic liquid probe by electrostatic enhancement for visual detection of Fe3+ in food

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2025-03, Vol.329, p.125473, Article 125473
• Main Authors: Che, Siying, Peng, Xiutan, Shen, Anbang, Yin, Linlin, She, Yuanbin, Fu, Haiyan
• Format: Article
• Language: English
• Subjects: Colorimetric probes; Electrostatic effect; Ferric ion; Ionic probe; Portable devices
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2024.125473

[Display omitted] •An ionic liquid was designed to detect Fe3+ in functional food with LOD of 0.2 μM.•The probe and Fe3+ were complexed in a ratio of 2: 1 confirmed by the job plot.•The probe achieved multi-color changes to detect Fe3+ by the naked eye.•A portable paper was made for visually detecting Fe3+ and applied in real samples. Excessive or insufficient iron(Ⅲ) will pose burdens of human body, and its content is the key to control the function of iron-fortified food. In this regard, a functionalized quinoline ionic probe, benefiting from the electrostatic attraction, was designed for the colorimetric detection of Fe3+ in food. This probe formed a 2: 1 complex with Fe3+, altering the UV–vis spectra and solution color. The UV–vis detection limit was 0.2 μM, and visually, the color shifted from light-yellow to dark-green as Fe3+ concentrations increased, with a visual detection limit of 3.4 μM, meeting the maximum acceptable level of 5.4 μM. Noteworthy, ionic liquid-based sensing paper was constructed for rapid, semi-quantitative Fe3+ detection. Furthermore, the satisfying recovery (97.4–102.9 %) was obtained in real samples, showcasing the probe’s efficiency. This work demonstrated the potential of ionic liquids for the fast, sensitive, and visual detection of Fe3+, offering a promising direction for metal element sensing platforms.