Search

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.

AbstractPimaricin (PMR) is a polyene antifungal drug commonly used as the primary medicine for treating fungal keratitis. In this study, a selective and novel spectrofluorimetric method was designed, optimized, and validated to determine pimaricin in its ophthalmic preparations. The method based on the formation of a nitrobenzoxadiazole-based yellow fluorophore upon the reaction of pimaricin with 4-chloro-7-nitro-1,2,3-benzoxadiazole (NBD-Cl). The fluorescence intensity of the fluorophore was measured at the emission wavelength of 538.5 nm (excitation = 473.5 nm). The factors affecting the reaction (reagent volume, alkalinity, reaction temperature, heating time, volume and type of buffer solution, and the dilution solvent) were investigated and optimized. The calculated linear range was 0.25–1.5 µg/mL, and the limits of detection and quantitation for the method were 0.047 and 0.143 µg/mL, respectively. The selectivity of the method for PMR in the presence of the pharmaceutical additive benzalkonium chloride was proved. The established method was successfully applied to determine PMR in its pharmaceutical ophthalmic preparation (Natamycin® ophthalmic drops) with an accuracy of 103.79 ± 1.83%. The proposed method is practical and valuable for its routine application in quality control laboratories for analysis of PMR in its ophthalmic pharmaceutical preparation. [ABSTRACT FROM AUTHOR]

AbstractA novel, uncomplicated, and sensitive spectrofluorimetric method was designed for the quantitative determination of bacitracin zinc in different water samples. This method depends on the proficient reaction of the primary amino group of bacitracin zinc with O-phthalaldehyde and 2-mercaptoethanol reagents in Teorell & Stenhagen buffer (in alkaline medium) producing fluorescent derivative with high intensity, which is determined at 436.5 nm with an excitation wavelength of 342.5 nm. The optimal experimental conditions influencing the derivatized product were cautiously studied and optimized. Under the optimized conditions, a linear relationship with an excellent correlation coefficient (0.9995) was found between the fluorescence intensity of the fluorophore and bacitracin zinc concentration in the range of 0.75–4.00 µg/mL. In addition, the limits of quantitation and detection for the developed method were 0.39 and 0.13 µg/mL, respectively. The accuracy and precision of the method were satisfactory; the values of recovery were in the range of 98.38-102.03%, and the relative standard deviations did not exceed 2.17%. The established method was employed effectively for bacitracin zinc determination in different water samples, which makes it a valuable concern for practical and rational quality control investigations of the studied drug. [ABSTRACT FROM AUTHOR]

Aspartame is an artificial sweetener used in drinks and many foods. International Agency for Research on Cancer classified aspartame as possibly carcinogenic to humans (IARC Group 2B). In this study, a sensitive and selective spectrofluorimetric method was developed to detect aspartame. The method is based on switching on the fluorescence activity of aspartame upon its condensation with O‐phthalaldehyde (Roth's reaction) in the presence of 2‐mercaptoethanol. The reaction product was detected fluorometrically at λem of 438 nm after λex of 340 nm. All reaction conditions required to yield the optimal fluorescence intensity were observed and investigated. Furthermore, the approach was validated according to ICH guidelines. Upon plotting the concentrations of aspartame against their associated fluorescence intensity values, the relationship between the two variables was linear within the range of 0.5–3.0 μg/mL. Furthermore, the method was employed to analyze the quantity of aspartame in commercial packages and soft drinks with an acceptable level of recovery. In addition, the Green Solvents Selecting Tool, Complementary Green Analytical Procedure Index, and the Analytical Greenness Metric tool were used to evaluate the sustainability and the greenness of the developed methodology. [ABSTRACT FROM AUTHOR]

Atopic dermatitis (AD) is a persistent, inflammatory skin condition that impacts approximately 15 to 20% of children and 1 to 3% of adults globally. Common skin manifestations include papules, papulovesicular, and brown or red patches with swelling, crusting, and flaking. Therefore, the drug abrocitinib (ABR) was approved by the US FDA as an oral treatment for atopic dermatitis. The present study outlines the development of innovative, thermostable, and pH‐stable organic solvent‐free nitrogen‐doped carbon dots (N@CQDs) synthesized through a one‐step method for evaluating ABR with a notable quantum yield of 33.84% to minimize the use of organic solvents. Their cost‐effectiveness, eco‐friendly characteristics, and outstanding photocatalytic properties have established them as a promising alternative to conventional luminescent techniques like fluorescent dyes and luminous derivatization technique. The reaction of ABR with N@CQDs led to a significant decrease in the luminescent response of the produced green and stable carbon quantum dots at 513 nm. The detection range was determined to be 1.0–150.0 ng mL−1, with a lower limit of quantitation (LOQ) equal to 0.52 ng mL−1 based on the linear graph. The green method effectively used for analysis of ABR in pharmaceutical tablets and pharmacokinetic study with high sensitivity. [ABSTRACT FROM AUTHOR]

In an acidic buffered solution, erythrosine B can react with amiodarone to form an association complex, which not only generates great enhancement in resonance Rayleigh scattering (RRS) spectrum of erythrosine B at 346.5 nm but also results in quenching of fluorescence spectra of erythrosine B at λemission = 550.4 nm/λexcitation = 528.5 nm. In addition, the formed erythrosine B–amiodarone complex produces a new absorbance peak at 555 nm. The spectral characteristics of the RRS, absorbance, and fluorescence spectra, as well as the optimum analytical conditions, were studied and investigated. As a result, new spectroscopic methods were developed to determine amiodarone by utilizing erythrosine B as a probe. Moreover, the ICH guidelines were used to validate the developed RRS, photometric, and fluorimetric methods. The enhancements in the absorbance and the RRS intensity and the decrease in the fluorescence intensity of the used probe were proportional to the concentration of amiodarone in ranges of 2.5–20.0, 0.2–2.5, and 0.25–1.75 μg/mL, respectively. Furthermore, limit of detection values were 0.52 ng/mL for the spectrophotometric method, 0.051 μg/mL for the RRS method, and 0.075 μg/mL for the fluorimetric method. Moreover, with good recoveries, the developed spectroscopic procedures were applied to analyze amiodarone in its commercial tablets. [ABSTRACT FROM AUTHOR]

In this study, netilmicin (NTM) was selectively assessed in its dosage forms after a facile derivatization reaction. The proposed approach was based on the interaction between NTM and o‐phthalaldehyde/2‐mercaptoethanol (Roth's reagent). The reaction product was fluorometrically measured at λemission of 434 nm after λexcitation of 338 nm. All reaction conditions for achieving the optimum fluorescence switch‐on activity were visualized and monitored. Moreover, the method was validated under ICH guidelines, and was linear over the range 30–210 ng/ml after plotting netilmicin concentrations against the corresponding fluorescence intensity values. In addition, the selectivity of the developed method was investigated against either the co‐formulated drug (dexamethasone) or a common ophthalmic drop excipient (benzalkonium chloride) without interference from either of them. Furthermore, the developed method was applied to assay netilmicin in various samples of pharmaceutical eye drops with good recovery. Finally, multicriteria greenness and whiteness metrics were used to evaluate the sustainability, greenness, and whiteness of the approach. The applied tools were the AGREE algorithm, the RGB 12 algorithm, and HEXAGON. [ABSTRACT FROM AUTHOR]