Utilization of N,S-Doped Carbon Dots as a Fluorescent Nanosensor for Determination of Cromolyn Based on Inner Filter Effect; Application to Aqueous Humor

A simple and eco-friendly hydrothermal technique is used to prepare water soluble N and S co-doped carbon quantum dots probe (N,S-CQDs) from thiosemicarbazide and citric acid. Several characterization techniques were performed in order to ensure well- synthesis of highly luminescent N,S-CQDs. The prepared probe exhibited analytical potential as optical nanosensor for the spectrofluorimetric determination of cromolyn sodium (CRO) in its pharmaceutical dosage forms and aqueous humor. The emission intensity of the synthesized N,S-CQDs was measured at 411 nm after excitation at 345 nm. Addition of increasing concentrations of CRO to N,S-CQDs led to quenching of its fluorescence intensity. CRO was investigated within wide concentration range of 10.0 to 150.0 μM with limit of detection of 2.0 μM and limit of quantification of 6.0 μM. The quenching of fluorescent N,S-CQDs occurs through inner filter effect (IFE). The developed spectrofluorimetric method was successfully optimized and validated according to International Council of Harmonization (ICH). Method greenness is proved through using both Eco-scale and AGREE approaches.