Luminescent Carbon Dots From Biomass Waste for the Sensitive Determination of Ascorbic Acid in Tablet Dosage Forms

Affordable and eco-friendly green spectrofluorometric (FL) methods can enhance the safety and cost-effectiveness of quality assurance and control in ascorbic acid (ASA) formulations. However, most current techniques for ASA analysis have faced challenges like complexity, delayed response times, low throughput, time-consuming procedures, and requirements for expensive equipment and hazardous chemicals for analyte modification. The study is aimed at producing natural carbon quantum dots (NACQDs) from pumpkin seed peels (PSPs), a natural waste material, using a rapid microwave-assisted method. A variety of techniques, including transmission electron microscopy, scanning electron microscopy, energy-dispersive x-ray spectroscopy, and Fourier-transform infrared spectroscopy, were employed to characterize the PSP-based NACQDs. The NACQDs were used as probes for FL analysis of ASA, where the addition of ASA caused fluorescence quenching of the NACQDs. The developed method demonstrated good linearity (r = 0.996), sensitivity, accuracy (percentage recovery ranging from 99.36% to 100.35%), and precision (%RSD less than 0.21%) in the quantification of ASA in the range of 0.3-15 μg/mL. The method's LOD and LOQ values were 0.1 and 0.3 μg/mL, respectively. The successful analysis of ASA in tablet formulations demonstrated the practicality of the proposed method. Greenness assessment tools highlighted its superior eco-friendliness compared to reference techniques.