Determination of aminophylline based on fluorescence quenching of amino-functionalized graphene quantum dots induced by photoilluminated riboflavin-aminophylline system

A new method based on fluorescence spectroscopy for the sensitive determination of aminophylline (AP), an antiasthmatic drug, was developed in this work. Amino-functionalized graphene quantum dots (afGQDs) were synthesized based on a two-step method and they were characterized by transmission electron microscope, UV–vis absorption spectrum and infrared spectrum. The fluorescence of afGQDs was quenched by riboflavin (Rf) via both dynamic quenching and inner filter effect. Photoilluminated Rf-AP system in the presence of oxygen produced hydroxyl radicals (OH). The latter accepted electrons from afGQDs owing to a photo-induced electron transfer process and led to the further fluorescence decline. The changing extent of the fluorescence intensity was found to be proportional to the concentration of AP in the range of 0.10–10 μg mL−1 and the limit of detection arrived at 40 ng mL−1. The proposed method was successfully employed for the determination of AP in a pharmaceutical sample and the recovery rate varied in the range of 99%–106%. [Display omitted] •The fluorescence of afGQDs was quenched by riboflavin due to dynamic quenching and IFE.•Photoilluminated riboflavin-aminophylline system produced hydroxyl radicals.•PET from afGQDs to OH led to the further decline of the fluorescence intensity.•A new method for the sensitive determination of aminophylline was developed.