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Following the sudden widespread of the novel coronavirus (COVID-19) which first appeared in Wuhan city. Remdesivir (REM) was the first medicine licensed by the US Food and Drug Administration (FDA) for COVID-19 infected hospitalized patients.Hence, there was an urgent demand for the optimization of efficient selective and sensitive methods to be developed for the determination of REM in pharmaceuticals as well as biological samples. A sensitive and simple green spectrofluorimetric

A novel, simple and sensitive spectrofluorimetric approach for determination of terbutaline sulphate (TER) and its prodrug bambuterol (BAM) in their pure and pharmaceutical dosage forms was developed. The suggested approach depends on enhancing the native fluorescence of either TER or BAM at 315 and 297.2 nm after excitation at 277 and 259 nm, respectively, using sodium dodecyl sulphate (SDS) as a micellar medium. In the presence of 0.7% w/v SDS, $1.38-fold and 1.18-fold enhancement is achieved in the relative fluorescence intensity (RFI) of TER and BAM, respectively. The fluorescence-concentration curves were rectilinear over the concentration range 0.8-16 μg ml À1 , with detection limits (LOD) of 0.252 and 0.26 (μg ml À1 ), quantitation limits (LOQ) of 0.76 and 0.79 (μg ml À1 ), determination coefficients (r2) of 0.9981, and slopes of 45.92 and 10.44 for TER and BAM, respectively. The suggested approach was validated in accordance with International Council for Harmonisation criteria and was effectively applied in the analysis of the studied drugs in their commercial tablets. The high sensitivity of the proposed approach allows its application in evaluating the content uniformity testing of the studied drugs in their tablets through using the official United States Pharmacopeia criteria. Statistical analogies of the findings with that of the reported methods showed really good harmony and indicated no major differences in precision and accuracy.

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Ribavirin (RIB) was successfully determined by fluorescence spectroscopy upon its quenching to environment friendly phosphorus and nitrogen co-doped carbon quantum dots (PNQDs). Different analytical parameters affecting the fluorescence spectra have been optimized and validated in accordance to the ICH guidelines. The proposed method has provided an efficient tracing of the interaction between RIB molecules and the synthesized QDs in an acidic medium (off-mode). The RIB molecules have shown excellent sensitivity by quenching of the emission band at 401 nm upon excitation at 245 nm throughout a linear range of 0.06–10.00 µg/mL with detection and quantitation limits down to 14.00 and 40.00 ng/mL, respectively. The quenching mode was proven to be static in raw samples and samples extracted of spiked plasma for quenching rate constants of 1.30 × 1012 L M−1 S−1 and 1.73 × 1012 L M−1 S−1, respectively. The proposed method has been successfully applied for determination of RIB in the commercial capsules and spiked human plasma samples with good recovery percentages in between 102.00 and 103.00%. Interestingly, these carbon dots have been utilized as nano-fluorescent platforms for assessment of the binding interaction kinetics between the RIB molecules and salmon sperm DNA (ssDNA). This has been implemented through peeling off the RIB molecules from surface of the PNQDs upon successive addition of the ssDNA and hence fluorescence restoration (turning on). Consequently, this provides  a successful monitoring of its antimicrobial potency. It was evidenced a strong binding interaction with a binding constant of 2.38 × 104 mol−1/L. Significantly, this could open doors for an extended application for on-site monitoring of RIB as well as its interactions with biomolecules and microorganisms.