Papers by Manal Mohamed Ibrahim Eid
Scientific Reports
COVID-19 is a fast-spreading pandemic that is caused by SARS-CoV-2 viral pathogen. Combination th... more COVID-19 is a fast-spreading pandemic that is caused by SARS-CoV-2 viral pathogen. Combination therapy of the antiviral favipiravir and the anticoagulant apixaban is one of the efficient treatment regimens. Therefore, development of novel and sensitive methods for simultaneous analysis of such combination is highly advantageous. Herein, two eco-friendly, simple, rapid, and cost-effective spectrofluorometric methods were evolved for the estimation of favipiravir and apixaban in pharmaceutical and biological matrices. Method I was based on analysis of favipiravir and apixaban by the first-order derivative of the conventional fluorescence spectra obtained after excitation at 300 nm, where favipiravir and apixaban were detected at 468.8 and 432.0 nm, respectively. Method II relied on dual scan synchronous spectrofluorometry, in which favipiravir was determined at 364 nm using Δλ = 60 nm while apixaban was analyzed at 274 nm using Δλ = 200 nm. Method optimization was performed for select...
Royal Society Open Science
A facile, accurate, eco-friendly and sensitive spectrofluorometric method was evolved to assay al... more A facile, accurate, eco-friendly and sensitive spectrofluorometric method was evolved to assay alfuzosin hydrochloride (AFH) and tadalafil (TDF) in different matrices. Such a co-administered combination is clinically used for the treatment of lower urinary tract symptoms. Both compounds are characterized by their native fluorescence spectra upon excitation at specific wavelengths. Their characteristic fluorescence spectra were used for sensitive assay of the studied analytes in tablets and human biological samples. The assay principle is based on first-order synchronous spectrofluorometric scan using Δλ= 60 nm in which AFH peaks were recorded at 366 nm. Meanwhile, TDF measurements were recorded at 293 nm in the same scans without overlap with AFH spectra. Recent analytical chemistry trends were implemented to lessen occupational and environmental perils, using ethanol as a diluting solvent for method optimization and application. Linearity ranges were 5.0–90.0 and 10.0–100.0 ng ml−1...
Royal Society Open Science, 2022
Three eco-friendly spectrophotometric methods were developed for determination of the novel antic... more Three eco-friendly spectrophotometric methods were developed for determination of the novel anticoagulant drug, betrixaban (BTX). The first method (method A) was based on direct analysis of BTX at 229.4 nm on the zero-order spectrum using methanol as the optimum solvent. While the second method (method B) was based on measuring difference absorption value (ΔA) of BTX at 335 nm, which was obtained from pH-induced spectral difference (difference spectra of BTX in 0.1 M NaOH versus 0.1 M HCl). The third method (method C) was based on measurement of the first-derivative amplitudes of BTX and its co-administered Ca channel blocker lercanidipine (LER) at 304 and 229 nm for simultaneous assay of BTX and LER, respectively. All methods were linear over concentration ranges of 1.0–20.0 and 8.0–80.0 µg ml−1for BTX in methods A and B, respectively, and of 1.0–20.0 and 1.0–25.0 µg ml−1for BTX and LER, respectively, in method C. The three methods were fully validated and assessed for greenness by...
Acta chimica Slovenica, 2011
Two rapid, simple, sensitive, selective and economic derivative spectrophotometric (first [D1] an... more Two rapid, simple, sensitive, selective and economic derivative spectrophotometric (first [D1] and second [D2]) and synchronous spectrofluorimetric (FDSFS and SDSFS) methods have been developed for the analysis of fexofenadine hydrochloride (FXD) in the presence of its different degradation products. Derivative spectrophotometry (D1) was used to measure FXD at 223 nm in the presence of its alkaline or acidic degradation products, and at 211 nm in the presence of its oxidative degradation product. Derivative spectrophotometry (D2) was used to determine FXD at 217 nm in the presence of its alkaline or acidic degradation products, and at 215 nm in the presence of its oxidative degradation product; the UV degradation product was measured at 211 nm. Synchronous spectrofluorimetry (FDSFS) was used to measure FXD in the presence of its alkaline or acidic degradation products at 406 nm, and at 367 nm in the presence of its oxidative or UV degradation products. Synchronous spectrofluorimetry...
Luminescence, 2011
ABSTRACTA highly sensitive and simple spectrofluorimetric method was developed for the determinat... more ABSTRACTA highly sensitive and simple spectrofluorimetric method was developed for the determination of loratadine (LRT) and desloratadine (DSL) in their pharmaceutical formulations. The proposed method is based on investigation of the fluorescence spectral behaviour of LRT and DSL in a sodium dodecyl sulphate (SDS) micellar system. In aqueous solution of acetate buffer of pH 4.5, the fluorescence intensities of both LRT and DSL were greatly enhanced (240%) in the presence of SDS. The fluorescence intensity was measured at 438 nm after excitation at 290 nm for both drugs. The fluorescence–concentration plots were rectilinear over the range 0.05–2.0 µg/mL for both LRT and DSL, with lower detection limits of 5.13 × 10−3 and 6.35 × 10−3 µg/mL for LRT and DSL, respectively. The method was successfully applied to the analysis of the two drugs in their commercial tablets, capsules and syrups, and the results were in good agreement with those obtained with the official or comparison method...
Journal of Pharmaceutical and Biomedical Analysis, 1998
Direct current and differential pulse polarography DPP were used for the determination of three p... more Direct current and differential pulse polarography DPP were used for the determination of three penicillins, namely, ampicillin, benzylpenicillin and carbenicillin, in pure form and in their dosage forms. The method is based upon treatment of penicillins with nitrous acid followed by polarographic measurement of the produced derivatives polarographically. The nitroso derivatives formed exhibited reduction waves over the whole pH range in Britton-Robinson buffers. The waves were characterized as being diffusion-controlled and free from adsorption phenomena. The current-concentration plots were rectilinear over the concentration range 8-200 and 2-160 mg ml − 1 for DC t and DPP, respectively, for all the studied compounds. The proposed method was further applied to determine penicillins in pharmaceutical preparations, and the results obtained were in good agreement with those given by the companies.
Journal of Pharmaceutical and Biomedical Analysis, 2001
A simple and specific reversed phase HPLC method for the determination of dinitrosopiperazine in ... more A simple and specific reversed phase HPLC method for the determination of dinitrosopiperazine in simulated gastric juice using UV detection was reported. The chromatographic resolution of the analyte and the internal standard isosorbide dinitrate was performed without extraction from the gastric juice on a reversed phase ODS column. Isocratic elution was carried out with methanol-0.02 M sodium dihydrogen phosphate (60:40 v/v, pH 3.0) at a flow rate of 1.0 ml min − 1 with UV detection at 238 nm. The calibration graph was linear over the concentration range 0.072-2.88 mg ml − 1 of dinitrosopiperazine with minimum detectability (S/N =2) of 0.01 mg ml − 1 (8× 10 − 8 M). Inter-day and intra-day precisions calculated as% RSD were in the range 0.32-0.38% and 0.19-0.25% respectively. Inter-day and intra-day accuracies calculated as% error were in the range 0.18-0.21 and 0.08-0.11% respectively. The proposed method was successfully applied to the study of the possible in-vivo production of DNPZ under the standard nitrosation conditions recommended by WHO.
Chemistry Central Journal, 2011
Two sensitive, selective, economic, and validated spectrofluorimetric methods were developed for ... more Two sensitive, selective, economic, and validated spectrofluorimetric methods were developed for the determination of ebastine (EBS) in pharmaceutical preparations depending on reaction with its tertiary amino group. Method I involves condensation of the drug with mixed anhydrides (citric and acetic anhydrides) producing a product with intense fluorescence, which was measured at 496 nm after excitation at 388 nm. Method (IIA) describes quantitative fluorescence quenching of eosin upon addition of the studied drug where the decrease in the fluorescence intensity was directly proportional to the concentration of ebastine; the fluorescence quenching was measured at 553 nm after excitation at 457 nm. This method was extended to (Method IIB) to apply first and second derivative synchronous spectrofluorimetric method (FDSFS & SDSFS) for the simultaneous analysis of EBS in presence of its alkaline, acidic, and UV degradation products. The proposed methods were successfully applied for the determination of the studied compound in its dosage forms. The results obtained were in good agreement with those obtained by a comparison method. Both methods were utilized to investigate the kinetics of the degradation of the drug.
Analytical Letters, 2009
Page 1. PHARMACEUTICAL ANALYSIS Spectrophotometric Determination of Risedronate and Etidronate in... more Page 1. PHARMACEUTICAL ANALYSIS Spectrophotometric Determination of Risedronate and Etidronate in Pharmaceutical Formulations via the Molybdovanadate Method Mohamed I. Walash, Mohamed E.-S. Metwally, Manal ...
Royal Society Open Science, 2021
A facile, rapid, accurate and selective quantitative proton nuclear magnetic resonance ( 1 H-qNMR... more A facile, rapid, accurate and selective quantitative proton nuclear magnetic resonance ( 1 H-qNMR) method was developed for the simultaneous determination of fluticasone propionate (FLP) and azelastine hydrochloride (AZH) in pharmaceutical nasal spray for the first time. The 1 H-qNMR analysis of the studied analytes was performed using inositol as the internal standard and dimethyl sulfoxide- d 6 (DMSO- d 6 ) as the solvent. The quantitative selective proton signal of FLP was doublet of doublet at 6.290, 6.294, 6.316 and 6.319 ppm, while that of AZH was doublet at 8.292 and 8.310 ppm. The internal standard (inositol) produced a doublet signal at 3.70 and 3.71 ppm. The method was rectilinear over the concentration ranges of 0.25–20.0 and 0.2–15.0 mg ml −1 for FLP and AZH, respectively. No labelling or pretreatment steps were required for NMR analysis of the studied analytes. The proposed 1 H-qNMR method was validated efficiently according to the International Council on Harmonisation...
Journal of AOAC INTERNATIONAL, 2007
A simple and sensitive fluorometric method for determination of ketorolac tromethamine was studie... more A simple and sensitive fluorometric method for determination of ketorolac tromethamine was studied. The method depends on oxidation of the drug with cerium(IV) and subsequent monitoring of the fluorescence of the induced cerium(III) at em 365 nm after excitation at 255 nm. Different variables affecting the reaction conditions, such as the concentrations of cerium(IV), sulfuric acid concentration, reaction time, and temperature, were carefully studied and optimized. Under the optimum conditions, a linear relationship was found between the relative fluorescence intensity and the concentration of the investigated drug in the range of 0.10.8 g/mL. No interferences could be observed from the excipients commonly present in dosage forms. The proposed method was successfully applied to the analysis of the investigated drug in its pure form, pharmaceutical preparations, and biological fluids with good accuracy and precision. The recoveries for pharmaceutical formulations ranged from 99.8101....
Eurasian Journal of Analytical Chemistry, Aug 7, 2014
Journal of the Chinese Chemical Society, 2007
A highly sensitive spectrofluorimetric method was developed for the determination of fenoterol HB... more A highly sensitive spectrofluorimetric method was developed for the determination of fenoterol HBr in pharmaceutical preparations. The method is based on the nitrosation of fenoterol followed by reaction with 2-cyanoacetamide in the presence of ammonia and measuring the produced fluorescence at 380 nm after excitation at 338 nm. All the variables affecting the reaction conditions were carefully studied and optimized. Linear calibration graph was obtained in the range of 0.064-0.64 μg.mL -1 with a correlation coefficient of 0.9999 and a relative standard deviation of 0.83%. The method was applied to dosage forms and the results obtained agreed well with those obtained by the official method. A proposal of the reaction pathway was suggested.
Journal of Liquid Chromatography & Related Technologies, 2014
Amparada nos preceitos da inclusão social, esta pesquisa objetivou examinar a empregabilidade das... more Amparada nos preceitos da inclusão social, esta pesquisa objetivou examinar a empregabilidade das pessoas com deficiência (PCD) em atendimento ao Decreto 3.298, que estabelece cotas para contratação de PCD para empresas com 100 ou mais funcionários. Foram entrevistados funcionários do setor de recursos humanos de 12 empresas de médio e grande porte de um município do oeste paulista, à luz de um roteiro estruturado. As entrevistas foram integralmente transcritas, categorizadas pelo critério da análise de conteúdo. Os resultados apontam que um terço das empresas privadas cumpre a regulamentação. As políticas empresariais priorizam contratações de pessoas cujas deficiências não exijam modificações estruturais no ambiente de trabalho, ou que então represente aspecto favorável à produção. A maioria dos entrevistados concebe a deficiência como um fenômeno de caráter individual. Embora tenham discursado sobre direitos iguais a todas as pessoas, grande parte ainda não apresenta discurso condizente com os pressupostos inclusivos, pois deixa de realizar ações de suporte para atender essa demanda populacional, esperando que o próprio indivíduo se ajuste às condições postas. Palavras-chave: Pessoa com deficiência, Mercado de trabalho, Inclusão social. Employment of people with disability: an analysis of social inclusion in the job market in the city of Bauru, SP Based on the precepts of social inclusion, this research objected to examine the employment of people with disability (PWD), according to decree nº 3.298 which establishes hiring quotas for PWD in companies with 100 or more employees. Interviews were made with employees of HR departments in 12 different companies located in the west side of the state of São Paulo, based on a structured script. All the interviews were transcripted and gathered in analysis categories. The results showed that one third of private companies comply with the regulation for employment of PWD. Corporate policies prioritize hiring of people whose disabilities do not demand structural modifications in the work environment, or those whose disabilities represent a positive aspect for production lines. The majority of the interviewed understand disabilities as an individual phenomenon. Although they have talked about equal rights for everyone, the majority of them do not present a consistent speech based on the precepts of social inclusion, for they fail to promote actions for supporting the population with disabilities and expecting that those with disabilities are the ones responsible to adjust themselves to all imposed conditions.
Journal of Fluorescence, 2010
A rapid, simple and highly sensitive first derivative synchronous fluorometric method has been de... more A rapid, simple and highly sensitive first derivative synchronous fluorometric method has been developed for the simultaneous analysis of binary mixture of sulpiride (SUL) and mebeverine hydrochloride (MEB). The method is based upon measurement of the synchronous fluorescence intensity of these drugs at ∆λ = 100 nm in water. The different experimental parameters affecting the fluorescence of the two drugs were carefully studied and optimized. The fluorescence-concentration plots were rectilinear over the range of 0.05-1 µg/mL and 0.2-3.2 µg/mL for SUL and MEB respectively with lower detection limits (LOD) of 0.006 and 0.01 µg/mL and quantification limits (LOQ) of 0.0.02 and 0.05 µg/mL for SUL and MEB, respectively. The proposed method was successfully applied for the determination of the two compounds in synthetic mixtures and in commercial tablets. The high sensitivity attained by the proposed method allowed the determination of both of SUL and MEB metabolite (veratic acid) in real human plasma samples applying second derivative synchronous fluorometric technique. The mean% recoveries (n = 3) for both MEB metabolite (veratic acid) and SUL were 99.82 ± 2.53 and 98.84 ± 6.20 for spiked human plasma respectively, while for real human plasma, the mean% recoveries (n = 3) were 91.49 ± 4.25 and 91.36 ± 8.46 respectively.
Journal of Fluorescence, 2011
A highly sensitive, simple and rapid stabilityindicating spectrofluorimetric method was developed... more A highly sensitive, simple and rapid stabilityindicating spectrofluorimetric method was developed for the determination of metolazone (MET) and xipamide (XPM) in their tablets. The proposed method is based on the measurement of the native fluorescence of MET in methanol at 437 nm after excitation at 238 nm and XPM in alkaline methanolic solution at 400 nm after excitation at 255 nm. The fluorescence-concentration plots were rectilinear over the range of 2.0-20.0 ng/mL for MET and 0.2-2.0 μg/mL for XPM, with lower detection limits (LOD) of 0.35 ng/mL and 0.02 μg/mL and a lower quantification limit (LOQ) of 1.05 ng/mL and 0.07 μg/mL for MET and XPM, respectively. The method was successfully applied to the analysis of MET and XPM in their commercial tablets and the results were in good agreement with those obtained using the official and comparison methods, respectively. Furthermore, content uniformity testing of the studied pharmaceutical tablets was also conducted. The application of the proposed method was extended to stability studies of MET and XPM after exposure to different forced degradation conditions, such as acidic, alkaline, oxidative and photolytic degradation conditions, according to ICH Guidelines. Moreover, the method was utilized to investigate the kinetics of the alkaline, acidic and photolytic degradation of MET. The apparent first-order rate constants and half-life times were calculated. Proposals for the degradation pathways for both MET and XPM were postulated.
Journal of Fluorescence, 2010
A simple, sensitive and rapid spectrofluorometric method for determination of methocarbamol in ph... more A simple, sensitive and rapid spectrofluorometric method for determination of methocarbamol in pharmaceutical formulations and spiked human plasma has been developed. The proposed method is based on the measurement of the native fluorescence of methocarbamol in methanol at 313 nm after excitation at 277 nm. The relative fluorescence intensity-concentration plot was rectilinear over the range of 0.05-2.0 μg/mL, with good correlation (r=0.9999), limit of detection of 0.007 μg/ mL and a lower limit of quantification of 0.022 μg/ mL. The described method was successfully applied for the determination of methocarbamol in its tablets without interference from co-formulated drugs, such as aspirin, diclofenac, paracetamol and ibuprofen, The results obtained were in good agreement with those obtained using the official method (USP 30).The high sensitivity of the method allowed the determination of the studied drug in spiked human plasma with average percentage recovery of 99.42 ± 3.84.
Journal of Fluorescence, 2011
A validated simple, rapid, and selective spectrofluorimetric method was developed for the determi... more A validated simple, rapid, and selective spectrofluorimetric method was developed for the determination of some antihistaminic H(1) receptor antagonist drugs namely ebastine (EBS), cetirizine dihydrochloride (CTZ), and fexofenadine hydrochloride (FXD). The method is based on the reaction of the cited drugs with some Π acceptors namely p-chloranilic acid (CLA), tetracyanoethylene (TCNE), and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) to give highly fluorescent derivatives. The fluorescence intensity-concentration plots were rectilinear over the concentration ranges of 0.2-3.0, 0.2-2.5 and 0.15-2.0 μg/ml for EBS with CLA, DDQ, and TCNE respectively; 0.5-7.0, 0.5-6.0, and 0.2-4.0 μg/ml for CTZ with the previously mentioned reagents, and 0.2-3.5, 0.5-6.0, and 0.2-3.5 μg/ml for FXD. The factors affecting the formation of the reaction products were carefully studied and optimized. The method was applied for the determination of the studied drugs in their dosage forms. The results obtained were in good agreement with those obtained by the comparison methods. Reactions Stoichiometries of the complexes formed between the studied drugs and Π acceptors were defined by the Job's method of the continuous variation and found in 1:1 in all cases.
Journal of Chromatographic Science, 2013
Micellar high-performance liquid chromatography (HPLC) and firstderivative ultraviolet spectropho... more Micellar high-performance liquid chromatography (HPLC) and firstderivative ultraviolet spectrophotometry were used to simultaneously determine fluconazole (FLZ) and tinidazole (TNZ) in combined pharmaceutical dosage forms. The derivative procedure is based on the linear relationship between the drug concentration and the first derivative amplitudes at 220 and 288 nm for FLZ and TNZ, respectively. The calibration graphs were linear in the range of 1.5-9.0 mg/mL for FLZ and 10.0-60.0 mg/mL for TNZ. Furthermore, an HPLC procedure with ultraviolet detection at 210 nm was developed. For the HPLC procedure, good chromatographic separation was achieved using an ODS C18 column (250 3 4.6 mm i.d.). The mobile phase containing 0.15M sodium dodecyl sulphate, 0.3% triethylamine and 12% n-propanol in 0.02M orthophosphoric acid at pH 5.5 was pumped at a flow rate of 1 mL/min. Indapamide was used as an internal standard. The method showed good linearity over the concentration ranges of 1.5-30.0 and 10.0-200.0 mg/mL, with limits of detection of 0.36 and 2.70 mg/mL and limits of quantification of 1.1 and 8.2 mg/mL for FLZ and TNZ, respectively. The suggested methods were successfully applied for the simultaneous analysis of the drugs in their laboratory prepared mixture, co-formulated tablet and single dosage forms. Moreover the second method was also extended to the determination of the drugs in biological fluids.
Journal of Chromatographic Science, 2011
Sensitive and accurate high-performance liquid chromatographic methods have been developed for th... more Sensitive and accurate high-performance liquid chromatographic methods have been developed for the simultaneous determination of thiocolchicoside (TC)-glafenine (GF) (Mix I) and thiocolchicoside-floctafenine (FN) (Mix II) in their pharmaceutical formulations. The analysis for both mixtures was performed using 250 mm × 4.6 mm i.d., 5 μm particle size C18 Waters Symmetry column. The mobile phase consisted of methanol-0.035 M phosphate buffer (50:50, v/v) of pH 4.5 for Mix I and methanol-0.03 M phosphate buffer (70:30, v/v) of pH 4 for Mix II with flow rate of 1 mL/min and UV detection at 400 nm in both cases. The calibration plots were rectilinear over the concentration range of 0.2-2 μg/mL for TC in both mixtures and 20-200 μg/mL for each of GF and FN . The limits of detection for TC and GF were 0.05 μg/mL and 0.62 μg/mL, respectively, and for TC and FN were 0.02 μg/mL and 0.70 μg/mL, respectively. Additionally, the proposed methods were successfully applied to their combined tablets with average percentage recoveries of 100.35 ± 0.61 and 100.57 ± 0.72% for TC and GF respectively and for TC and FN the percentage recoveries were 101.2 ± 0.72 and 100.36 ± 0.67%, respectively. The results obtained were favorably compared with those given using the comparison methods.
Uploads
Papers by Manal Mohamed Ibrahim Eid