LAUSR

Abstract The presence of histamine in foods due to improper storage of foods is associated with toxicological risk and quality indicators. An impedimetric sensor was developed by immobilising fluoro-substituted hydroxyl functionalised Schiff base zinc(II) complex on the titanium dioxide nanoparticles-coated fluorine-doped tin oxide (nano-TiO2/FTO) electrode for sensitive and selective determination of histamine with high recovery ability. Elucidation of chemical structure for the Zn(II)-Schiff base complex has been conducted by employing NMR, FTIR and ESI-MS spectroscopic techniques, whilst Schiff base complex-histamine binding affinity was evaluated by means of Raman spectroscopy, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrochemical impedimetric sensor showed charge-transfer resistance (Rct) response that is proportional to the logarithm of histamine concentration between 1.0 × 10−7 M and 1.0 × 10−2 M (R² = 0.9894), which is useful for the determination of typical histamine levels in food samples. The impedimetric sensor exhibited high selectivity towards histamine over other biogenic amines occurring in foods e.g. putrescine and cadaverine, and some other amine compounds e.g. ethanolamine (1˚ amine), 1,2-phenylenediamine (1,2-PDA, 2˚ amine) and triethylamine (TED, 3˚ amine). The Schiff base complex electrode is reusable, and rapid regeneration of the electrode within 30 s simply by using water allows high-throughput histamine assay. Impedimetric detection of histamine in salmon fillet at the Schiff base complex electrode has been validated with HPLC and showed high promise to be applied as an inexpensive and effective tool for food safety surveillance.