Carbon quantum dots as nanosensors for the spectrofluorimetric determination of meloxicam in biological fluids and dosage forms: Greenness assessment and application to content uniformity testing

Highly fluorescent water-soluble carbon quantum dots (CQDs) were synthesized via a simple onestep hydrothermal-assisted synthesis procedure utilizing ascorbic acid as a carbon source. The synthesized CQDs were characterized using different spectroscopic and microscopic methods. The quantum yield of the produced CQDs was studied and revealed a value of as high as 53.3%. The emission of CQDs at 534 nm after excitation at 371 nm was quantitatively quenched in presence of meloxicam (MLX), and revealed a calibration plot with a good linearity relationship over a concentration range of 1.5 -30.0 mu M and a lower quantitation and detection limits of 0.74 and 0.24 mu M, respectively. The proposed method was utilized for the estimation of MLX in different pharmaceutical preparations, including tablets, capsules, and ampoules with accepted % recovery values (98.7 -101.0). The developed method was extended for the content uniformity testing of tablets and capsules dosage units according to British Pharmacopeia requirements. Owing to the high sensitivity of the proposed approach, MLX was successfully determined in spiked human plasma samples. The developed method was validated according to ICH Q2(R1) guidelines. The current study introduces the first CQD-based spectrofluorimetric method for the estimation of the studied drug without the need for any derivatizing reagents or drastic chemical conditions. In order to assess the environmental sustainability of the developed approach, AGREE, GAPI, EcoScale, and NEMI metric tools were employed. They revealed that the developed approach is excellent green, suggesting its usage as an environmentally-friendly alternative for the routine assay of the investigated drug.