Carbon dots-based fluorescent probe for the detection of imidacloprid residue in leafy vegetables

Consumption of leafy vegetables with excessive imidacloprid (IMI) can cause serious harm to the human body. To achieve rapid IMI detection, a carbon dots (CDs)-based fluorescent (FL) probe was hydrothermally prepared using O-phenylenediamine as the precursor. The morphology, particle size distribution, crystal structure, optics and chemical bond state of the as-prepared CDs were characterized. The mechanism of the CDs in detecting IMI was investigated by Fourier transform infrared spectroscopy, and the CDs' selectivity, stability, sensitivity, and actual sample recovery were tested. The CDs showed good selectivity, stability, and anti-interference ability. Under optimum conditions, there was a strong linear relationship between the FL intensity of the CDs and the IMI concentration in the range of 0.037-0.2 mg/L. The detection limit was 0.00187 mg/kg. The CDs were successfully applied to detect IMI in lettuce, cole, spinach, and pakchoi with spiked recoveries between 81.026% and 106.803% and a relative standard deviation between 0.001 and 0.027%.