Highly luminescent S,N co‐doped carbon quantum dots‐sensitized chemiluminescence on luminol–H₂O₂ system for the determination of ranitidine

S,N co‐doped carbon quantum dots (N,S‐CQDs) with super high quantum yield (79%) were prepared by the hydrothermal method and characterized by transmission electron microscopy, photoluminescence, UV–Vis spectroscopy and Fourier transformed infrared spectroscopy. N,S‐CQDs can enhance the chemiluminescence intensity of a luminol–H 2 O 2 system. The possible mechanism of the luminol–H 2 O 2 –(N,S‐CQDs) was illustrated by using chemiluminescence, photoluminescence and ultraviolet analysis. Ranitidine can quench the chemiluminescence intensity of a luminol–H 2 O 2 –N,S‐CQDs system. So, a novel flow‐injection chemiluminescence method was designed to determine ranitidine within a linear range of 0.5–50 μg ml −1 and a detection limit of 0.12 μg ml −1 . The method shows promising application prospects.