This study introduces the first reported stepwise fluorimetric strategy for the sensitive and rapid determination of the ultra-short-acting β₁-blocker, landiolol hydrochloride. Initially, an environmentally benign method was developed by exploiting the drug’s native fluorescence in water (λex/λem = 217/298 nm). While this cost-effective approach successfully utilized water as a green solvent, it demonstrated limited LOD of 32.57 ng/mL. To enhance fluorescence performance, various organic solvents were investigated, with acetonitrile providing the highest signal at λex/λem = 222/300 nm and improving the LOD to 16.31 ng/mL. To enable ultra-trace clinical monitoring, a third “turn-on” method was developed using silver nanoparticles (AgNPs). By measuring fluorescence enhancement at λex/λem = 260/524.6 nm upon interaction with landiolol, this platform amplifies the signal, achieving an outstanding LOD of 3.10 ng/mL. AgNPs were prepared using a green synthesis approach employing Aloe vera extract as a natural reducing and stabilizing agent in an aqueous medium avoiding using hazardous chemicals. Water was used throughout both nanoparticle preparation and the AgNP-enhanced determination, reinforcing the eco-friendly profile of the method. Unlike native fluorescence, the AgNP-assisted method enhances sensitivity through nanoparticle-mediated surface passivation, with a possible auxiliary contribution from resonance energy transfer (RET)-like processes. Selectivity is improved through preferential adsorption of landiolol on the AgNP surface and a large Stokes shift that minimizes interference from UV-absorbing matrix components. The resulting enhanced sensitivity and reduced matrix interference make this method a powerful tool for ultra-trace, selective, and sustainable determination of landiolol in pharmaceutical formulations and human plasma, demonstrating its suitability for routine quality control and bioanalytical applications.
A simple, sensitive, and eco-friendly spectrofluorimetric method has been developed for the determination of betahistine in bulk powder and tablet formulations. The method relies on fluorescence quenching of eosin Y at 540 nm (λex = 335 nm) through formation of a non-fluorescent ion-pair complex between the dye and protonated betahistine in acetate buffer (pH 3.8). Key experimental parameters—including buffer pH, buffer volume, eosin concentration, and diluting solvent—were optimized to maximize sensitivity. Under the selected conditions, a linear calibration curve was obtained over 1.0–5.0 µg mL⁻¹ with an excellent correlation coefficient (r = 0.9996). Limits of detection and quantification were 0.17 and 0.51 µg mL⁻¹, respectively. Validation according to International Council for Harmonization Q2 (R1) guidelines confirmed high accuracy (mean recovery 99.06%) and precision (RSD < 2%). The method was successfully applied to commercial tablets without interference from excipients, and results showed no significant difference compared with a reported spectrophotometric method. Owing to its simplicity, sensitivity, and exclusive use of aqueous media, the procedure is well-suited for routine pharmaceutical quality control.
Tamer Z. Attia, Huda H. Saied, D. A. M. N. El-Deen et al.· Scientific Reports· 0 citations
A sensitive and environmentally friendly spectrofluorimetric method was developed for the determination of guanfacine in pharmaceutical formulations. The method is based on derivatization of guanfacine with 4-chloro-7-nitrobenzofurazan in alkaline medium to yield a highly fluorescent product measured at 535 nm after excitation at 466 nm. Experimental conditions affecting the reaction were systematically optimized to achieve maximum fluorescence intensity. The method exhibited excellent linearity over the concentration range of 50–500 ng/mL with a correlation coefficient of 0.9994. The limits of detection and quantitation were found to be 13.80 and 41.82 ng/mL, respectively, indicating high sensitivity. The method was validated in accordance with ICH guidelines and demonstrated satisfactory accuracy, precision, robustness, and selectivity. It was successfully applied to the analysis of guanfacine in commercial tablet formulations without interference from excipients. Greenness assessment using Analytical Eco-scale and AGREE tools confirmed the environmentally benign nature of the method, achieving a high Eco-scale score of 89 and an AGREE score of 0.68. Compared with a reported method, the proposed approach offers improved sensitivity and superior environmental benignity, making it suitable for routine quality control analysis.
Aamal A. Al-Mutairi, Saleh I. Alaqel, Farooq M. Almutairi et al.· Scientific Reports· 0 citations
The pervasive use of pyrethroids and their potential for bioaccumulation necessitate the development of rapid, broad-spectrum, and field-deployable monitoring tools. A novel sensing strategy using fluorinated silicon quantum dots (FSiQDs) for the indirect detection of pyrethroids was developed by targeting their universal degradation product, 3-phenoxybenzaldehyde (3-PBD). FSiQDs modified with 3,5-difluorophenylhydrazine exhibited superior quenching rate (71.32%) toward 3-PBD through a Schiff base-mediated static quenching mechanism. Under optimized conditions, the sensor achieved a limit of detection (LOD) of 0.28 μM within a 10 min response time. To facilitate on-site analysis, an integrated portable fluorescence detector (PFD) was engineered, demonstrating reliable performance in waters from Taihu, Yangcheng, and Cheng Lakes with recoveries ranging from 96.96% to 102.67%. This work represents the first application of fluorine-doped SiQDs for fluorescence sensing, offering a practical solution for the rapid, broad-spectrum screening of pesticide residues in complex environmental and food matrices.
K. Zhao, Yuheng Zhao, Yuemao Dou et al.· Analytical Chemistry· 0 citations
The increasing occurrence of pharmaceutical residues in biological and environmental matrices has created a demand for sensitive, selective, and sustainable analytical methods for their determination. Letrozole (LTR) and bicalutamide (BCL), two non-steroidal anticancer drugs co-administered for the treatment of testotoxicosis, exhibit native fluorescence; however, their emission spectra significantly overlap, preventing their direct simultaneous determination. In this work, a green synchronous spectrofluorimetric method was developed to overcome this limitation by improving spectral resolution through synchronous scanning of the excitation and emission monochromators. Under the optimized conditions (Δλ = 50 nm), LTR and BCL were directly quantified at 240 and 272 nm, respectively, without prior separation or derivatization. The proposed method showed linear responses over concentration ranges of 0.5–150.0 ng mL−1 for LTR and 5.0–1000.0 ng mL−1 for BCL, with limits of detection of 0.09 and 1.29 ng mL−1, respectively. The method was validated according to ICH guidelines and demonstrated satisfactory accuracy, precision, selectivity, and reproducible analytical performance. Its applicability was confirmed by the simultaneous determination of both analytes in pharmaceutical formulations, spiked human plasma and urine, and environmental water samples, providing satisfactory recoveries with minimal matrix interference. In addition, the method requires minimal solvent consumption and avoids hazardous reagents, and its environmental sustainability was confirmed using the Analytical Green Star Area (AGSA) and Multi-color Assessment (MA) tools.
A. Alrashidi, Galal Magdy, A. Radwan· RSC Advances· 0 citations
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