A simple and highly sensitive spectrofluorimetric method for the estimation of sumatriptan succinate has been investigated. The suggested method depends on the determination of the intrinsic fluorescence properties of the drug in aqueous systems at λem 350 nm following λex at 225 nm. The linearity range was 10–100 ng/ml, with a detection limit and quantitation limit of 1.2 and 3.6 ng/ml, respectively. The suggested method was sufficiently successful for determination of sumatriptan its pharmaceutical tablets as well as in spiked human plasma. Moreover, the validation parameters were determined following International Council for Harmonisation guidelines. Statistical analysis of the obtained results from the proposed and reference methods showed no significance difference between the two methods regarding accuracy and precision.

A facile green microwave-assisted method was developed for the production of highly fluorescent nitrogen doped carbon quantum dots (N-CQDs) using sucrose and urea as starting materials. The fluorescent N-CQDs were utilized as nano-sensors for the spectrofluorimetric estimation of furosemide after subjecting to extensive spectroscopic characterization. The quantum yield of the obtained N-CQDs was found to be 0.57. After excitation of the produced N-CQDs at 216 nm, a strong emission band appeared at 376 nm. The fluorescence emission of N-CQDs was quantitatively quenched by adding increased concentrations of the drug. A linear relationship was obtained over the concentration range of 0.1–1.0 μg/mL. The developed method was successfully applied for the estimation of furosemide in its pharmaceutical preparations and biological samples. The mechanism of the quenching was studied and explained. Interference likely to be introduced from co-administered drugs was also studied.

Highly fluorescent nitrogen doped carbon quantum dots (N-CQDs) were prepared by a single-step method based on microwave heating of cane sugar and urea. The produced N-CQDs were applied as nano-sensors for the spectrofluorimetric determination of eplerenone and spironolactone. A strong emission band at 376 nm was obtained after excitation at 216 nm due to the produced N-CQDs. The native fluorescence of N-CQDs was obviously quenched upon adding increased concentrations of each drug. A strong correlation was found between the fluorescence quenching of N-CQDs and the concentration of each drug. The method was found to be linear over the range of 0.5 to 5.0 μg/mL for eplerenone and 0.5 to 6.0 μg/mL for spironolactone with LOQ of 0.383 μg/mL and 0.262 μg/mL. The developed method was further extended for determination of both drugs in their pharmaceutical tablets and spiked human plasma. The results obtained were statistically compared with those of reported methods. The mechanism of fluorescence quenching of N-CQDs by the two drugs was discussed.