Rapid microwave-assisted synthesis of copper nanoclusters for “on-off-on” fluorescent sensor of tert-butylhydroquinone in edible oil

[Display omitted] •A rapid microwave-assisted synthesis for L-Cys-CuNCs.•An on-off-on strategy was employed to detect TBHQ using L-Cys-CuNCs.•The TBHQ detection limit as low as 77 ng·mL−1.•The sensor was used for the TBHQ determination in edible oil. Copper nanoclusters (CuNCs) are attractive alternatives for fluorescent sensor, due to their low toxicity, strong biocompatibility, and inexpensive manufacturing cost. Herein, fluorescent CuNCs was rapidly synthesized in 2.5 min under microwave irradiation using L-cysteine (L-Cys) as the protective and reducing agent, and an “on-off-on” fluorescent sensor for tert-butylhydroquinone (TBHQ) was developed. In the presence of Fe3+ ions, the fluorescence of L-Cys-CuNCs was quenched (turned off), then recovered after adding TBHQ (turn on). Under the optimized conditions, the TBHQ sensor had a wide linear range (2–350 μmol·L−1) and low detection limit (0.077 μg·mL−1). Furthermore, the relative standard deviation (RSD) were from 1.44% to 8.98% and the recoveries were from 94.53% to 108.99% for the determination of edible oil samples. Besides, the results detected by fluorescence sensor is in accordance with the results obtained in the traditional HPLC method. The microwave-assisted fast synthesis of CuNCs will expected to develop the fluorescent sensors for food safety and environmental analysis.