Ali A. Ensafi, Parisa Nasr-Esfahani, B. Rezaei,

An optical sensor based on carbon quantum dots (CQDs) coated with molecularly imprinted polymers (MIPs) was fabricated for selective and sensitive determination of promethazine hydrochloride (PrHy). Water-soluble and fluorescent CQDs were synthesized by a simple, low cost and green approach using orange juice as a carbon source. The special advantage of the synthesized CQDs with this method is low toxicity. The surface of the CQDs was covered with MIPs matrix (CQDs-MIPs) via sol-gel polymerization. For characterization of the CQDs and CQDs-MIPs, UV–vis absorption spectroscopy, fluorescence spectroscopy, dynamic light scattering technique, X-ray diffraction technique, Fourier transform infrared spectroscopy, and transmission electron microscopy were used. The fluorescence intensity of CQDs-MIPs exhibited linear response with the concentration of PrHy in the range from 2.0 to 250 mol L−1 with a detection limit of 0.5 mol L−1. The reproducibility of the method was checked for 20 mol L−1 of PrHy, and the results showed RSD% as 5.1. This sensor was used for determination of PrHy in real samples and showed satisfactory results.