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Abstract The psychoanaleptic medication atomoxetine (ATX) is prescribed to cure attention-deficit hyperactivity syndrome. ATX works by selective prevention of norepinephrine reuptake. It acts by raising the brain’s natural level of norepinephrine, which is necessary for behavior regulation. In this study, a sensitive and practical experimental method was employed to analyze the presence of ATX. The approach utilized a green chemistry-compatible technique, known as a one-pot experiment. The main principle behind this method was the use of molecular-size-dependant resonance Rayleigh scattering (RRS) phenomenon, which occurred due to the interaction between the dual complex of Cilefa Pink B and ATX. When ATX medication and Cilefa Pink B were combined in an acidic environment, they formed an association complex, leading to an amplification of the RRS signal. This amplification directly correlated with the concentration of ATX, specifically within the range of 40-1250 ng/mL. The RRS signal was monitored at a wavelength of 352 nm. The sensitivity of the method was demonstrated by the determination of the limit of detection (LOD) at 12.9 ng/mL and the limit of quantitation (LOQ) at 39.2 ng/mL. The variables of the method were thoroughly investigated and optimized. To ensure the reliability of the method, it was validated according to the International Council for Harmonisation (ICH) guidelines. Furthermore, the method was successfully applied to analyze ATX in its prescribed dosage form. The achievement of using the established resonance Rayleigh scattering (RRS) technology to analyze the target drug in plasma and ensure content uniformity was a remarkable feat.

Levamisole is an anti-helminthic agent employed medically to treat worm-causative disease, also used as an immune system modifying agent in rheumatic arthritis and as assistant therapy for treating the cancers of the head, colorectal, and neck regions. The first innovative size-dependent approach for levamisole drug analysis is described in this study. It is both efficient and environmentally benign. The drug was evaluated and validated using a green, one-pot, and direct size-dependent technique in this approach. An instant complex was created by combining levamisole and Cilefa Pink B in a mildly acidic medium. The fluorimetric investigation was based on the augmentation effect of levamisole on the Rayleigh scattering response amplitude of a biological dye (Cilefa Pink B) at 424 nm. which was related to produced complex's molecular size. Linearity ranged from 0.08 to 2.0 µg mL−1, with sensitivity limits of 0.023 and 0.069 µg mL−1, respectively. Analytical modulation of Levamisole-Cilefa Pink B complexes was done for all system parameters. In addition, the system was found to meet ICH criteria. Moreover, this technique successfully recovered the substance in the prescribed medicinal dosage forms. The created fluorimetric technique was also successfully employed to track the drug of interest in human biofluids, which was a significant accomplishment. Finally, an eco-scale was applied to recognize the designed method's environmental friendliness.

A stable Au metal organic frameworks (AuMOF) nanosol was prepared. It was characterized by electron microscopy and molecular spectral techniques. In pH 6.8 PBS buffer solution, AuMOF nanoprobes exhibit a strong resonance Rayleigh scattering (RRS) peak at 330 nm. After basic fuchsin (BF) adsorbing on the surface of AuMOF, the RRS energy of the nanoprobe donor can be transferred to BF receptor, resulting in a decrease in the RRS intensity at 330 nm. Both sulfite and BF taken place an addition reaction to form a colorless product (SBF) that exhibit weak RRS energy transfer (RRS-ET) between AuMOF and SBF, resulting in the enhancement of the RRS peak. As the concentration of SO32–increases, the RRS peak is linearly enhanced. Thus, a new and sensitive RRS-ET method for the detection of SO32– (0.160–5.00 μmol/L) was developed accordingly using AuMOF as nanoprobes, with a detection limit of 0.0800 μmol/L. This new RRS method was applied to determination of SO32– in food and SO2 in air samples. The recoveries of food and air samples were 97.1–106% and 92.9–106%, and the relative standard deviation (RSD) was 2.10–4.80% and 2.10–4.50%, respectively.

In this work, a resonance Rayleigh scattering technique and a spectrofluorimetric technique were applied to the quantification of cyclobenzaprine through two validated methods. The suggested methods are based on a facile association complex formation between cyclobenzaprine and eosin Y reagent in the acidic medium. The resonance Rayleigh scattering method relied on the enhancement in the resonance Rayleigh scattering spectrum of eosin Y at 370 nm after the addition of cyclobenzaprine. On the other hand, the spectrofluorimetric quantification relied on the quenching effect of cyclobenzaprine on the fluorescence strength of the eosin Y reagent at 545 nm (excitation wavelength at 300 nm). The suggested methods were linear over the ranges of 0.07–1.75 μg/mL and 0.15–2.0 μg/mL with detection limit values of 0.023 μg/mL and 0.048 μg/mL for the resonance Rayleigh scattering method and the spectrofluorimetric method, respectively. All reaction conditions for cyclobenzaprine–eosin Y formation were experimentally evaluated and optimized. In addition, both methods were validated based on ICH rules. Furthermore, the developed methods were practically applied to the analysis of cyclobenzaprine in its commercial tablet dosage form with acceptable recoveries. Moreover, the content uniformity test of the commercial cyclobenzaprine tablets was successfully applied using the proposed spectroscopic methods based on USP rules.

Duloxetine is an antidepressant that exhibits its action by preventing the reuptake of serotonin and norepinephrine by neurons. In this analytical study, we developed two facile, sensitive methods for duloxetine analysis. Both methods rely on the formation of binary association complex between erythrosine-B and duloxetine in an acidic medium using spectrofluorimetric and resonance Rayleigh scattering (RRS) techniques. Spectrofluorimetric method simply uses the quenching property of the formed complex on the native fluorescence of erythrosine-B at an emission wavelength of 557.2 nm (λex = 528.6), while RRS is based on detecting the enhancement in the RRS signal at 357.2 nm. The proposed methods have been validated according to the International Conference on Harmonization guidelines. The approaches provide linear assay of duloxetine hydrochloride over 0.1–2.4 µg ml−1 and 0.2–2.0 µg ml−1 for spectrofluorimetric and RRS methods, respectively. Variables affecting methods and complex formation were studied and optimized. The limit of detection values were 0.03 and 0.056 µg ml−1 for spectrofluorimetric and RRS methods, respectively. Both approaches were applied with acceptable results for formulation analysis and evaluation of cymbatex capsule content uniformity.

Sensitive and selective methods for the determination of urea in samples such as dairy products are important for quality control and health applications. Using ammonium ferric citrate as a precursor, Fe/N-codoped carbon dots (CDFeN) were prepared by a hydrothermal procedure and characterized in detail. CDFeN strongly catalyzes the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) by H2O2 to turn on an indicator molecular reaction, forming an oxidized tetramethylbenzidine (TMBox) probe with surface-enhanced Raman scattering, resonance Rayleigh scattering, and fluorescence (SERS, RRS, and FL) signals at 1,598 cm−1, 370 nm, and 405 nm, respectively. The urea aptamer (Apt) can turn off the indicator reaction to reduce the tri-signals, and the addition of urea turns on the indicator reaction to linearly enhance the SERS/RRS/FL intensity. Thus, a novel Apt turn-on tri-mode method was developed for the assay determination of ultra-trace urea with high sensitivity, good selectivity, and accuracy. Trace adenosine triphosphate and estradiol can also be determined by the Apt-CDFeN catalytic analytical platform.

Terbinafine hydrochloride is a potent antifungal drug indicated for oral and topical treatment of mycoses. A resonance Rayleigh scattering (RRS) method was developed for the determination of terbinafine hydrochloride through a feasible complexation reaction with erythrosine B. In a weakly acidic medium (acetate buffer, pH 5.0), terbinafine hydrochloride can react with erythrosine B through the electrostatic attraction and virtue of hydrophobic force to form an ion-association complex. The reaction resulted in the appearance of a new RRS peak at 369 nm. The RRS peak was increased by increasing the concentration of terbinafine hydrochloride in the linear range of 0.1–1.5 µg ml−1. All the reaction conditions (erythrosine B concentration, buffer volume, diluting solvent and pH) were optimized. The detection limit was 0.029 µg ml−1 while the quantitation limit was 0.089 µg ml−1. The suggested method after its validation was successfully applied for the determination of terbinafine hydrochloride in different pharmaceutical formulations (tablets and cream) with sufficient recovery.

Organotrialkoxysilanes like 3-aminopropyltrimethoxysilane (3-APTMS)-treated noble metal cations were rapidly converted into their respective nanoparticles in the presence of 3-glycidoxypropylytrimethoxysilane (3-GPTMS). The micellar activity of 3-APTMS also allowed us to replace 3-GPTMS with other suitable organic reagents (e.g., formaldehyde); this approach has significant advantages for preparing bimetallic and trimetallic analogs of noble metal nanoparticles that display efficient activity in many practical applications. The formation of monometallic gold, silver, and palladium nanoparticles, bimetallic Ag-Pd, and Au-Pd nanoparticles at various ratios of noble metal cations, and trimetallic Ag-Au-Pd nanoparticles were studied; their biocatalytic activity in non-enzymatic sensing of glucose based on monitoring synchronous fluorescence spectroscopy (SFS) was assessed. Of these nanoparticles, Au-Pd made with an 80:20 Au:Pd ratio displayed excellent catalytic activity for glucose sensing. These nanoparticles could also be homogenized with Nafion to enhance the resonance Rayleigh scattering (RRS) signal. In this study, the structural characterization of noble metal nanoparticles as well as bi- and tri-metallic nanoparticles in addition to their use in non-enzymatic sensing of glucose are reported.