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Shereen Shalan

Mansoura University, Depatment of Analytical Chemistry, Assistant Professor

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I am associat professor in analytical chemistry department faculty of pharmacy Mansoura university, Egypt. My experts are in chromatography, spectroscopy, computer science, food analysis and drug analysis in biological fluids.

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Mahmoud Elkhoudary

Sinai University

Mansoura University

Tanta University

Mohammed Hammouda

Mansoura University

Mansoura University

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Papers by Shereen Shalan

Conventional and synchronous spectrofluorometric determination of the recently administered drugs for treatment of COVID-19 favipiravir and apixaban

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...

Inspection of antimicrobial remains in bovine milk in Egypt and Saudi Arabia employing a bacteriological test kit and HPLC-MS/MS with estimation of risk to human health

PLOS ONE, 2022

Veterinary medicine uses antibiotics randomly for treatment and growth promotion. Milk of dairy a... more Veterinary medicine uses antibiotics randomly for treatment and growth promotion. Milk of dairy animals contains substantial quantities of antibiotics that have harmful effects on health. It is therefore necessary to test commercially available milk using immunological, chromatographic, or microbiological methods to confirm the absence of antibiotic residues. This study aims to perform a microbiological test, followed by a quantitative confirmation analysis, on raw milk to assess the presence of antibiotic residues. Tests were conducted on 200 milk samples collected from markets and farms in Saudi Arabia and Egypt. The microbial inhibitor test (Delvotest SP-NT) revealed that 40 samples were positive for antibiotic residues. The positive samples were further tested using liquid chromatography-tandem mass spectrometry (LC-MS/MS) as a confirmatory quantitative test for 29 antibiotics that belong to five groups: tetracyclines, sulfonamides, fluoroquinolones, macrolides, and lactamases. Only four samples tested positive for oxytetracycline residues above the maximum residue limit. Based on these results, researchers suggest a monitoring system that considers both microbial and HPLC-MS/MS methods when detecting antibiotic residues in bovine milk. The analysis of risk to human health revealed that antibiotic residues at the detected levels do not pose any health risks to consumers.

A synchronous spectrofluorometric technique for simultaneous detection of alfuzosin and tadalafil: applied to tablets and spiked biological samples

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 Δ λ = 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...

Utilization of N,S‐Doped Carbon Dots as a Fluorescent Nanosensor for Determination of Cromolyn Based on Inner Filter Effect; Application to Aqueous Humor

Luminescence, 2022

A simple and eco-friendly hydrothermal technique is used to prepare water soluble N and S co-dope... more A simple and eco-friendly hydrothermal technique is used to prepare water soluble N and S co-doped carbon quantum dots probe (N,S-CQDs) from thiosemicarbazide and citric acid. Several characterization techniques were performed in order to ensure well- synthesis of highly luminescent N,S-CQDs. The prepared probe exhibited analytical potential as optical nanosensor for the spectrofluorimetric determination of cromolyn sodium (CRO) in its pharmaceutical dosage forms and aqueous humor. The emission intensity of the synthesized N,S-CQDs was measured at 411 nm after excitation at 345 nm. Addition of increasing concentrations of CRO to N,S-CQDs led to quenching of its fluorescence intensity. CRO was investigated within wide concentration range of 10.0 to 150.0 μM with limit of detection of 2.0 μM and limit of quantification of 6.0 μM. The quenching of fluorescent N,S-CQDs occurs through inner filter effect (IFE). The developed spectrofluorimetric method was successfully optimized and validated according to International Council of Harmonization (ICH). Method greenness is proved through using both Eco-scale and AGREE approaches.

Use of Green-Modified Micellar Liquid Chromatography For the Determination of Imidocarb Dipropionate Residues in Food Samples

Microchemical Journal

Supplementary material from "Simultaneous evaluation of losartan and amlodipine besylate using second-derivative synchronous spectrofluorimetric technique and liquid chromatography with time-programmed fluorimetric detection

This study is concerned with two sensitive, fast and reproducible approaches; namely, second-deri... more This study is concerned with two sensitive, fast and reproducible approaches; namely, second-derivative synchronous fluorimetry (method I) and reversed phase high-performance liquid chromatography with fluorimetric detection (method II) for synchronized evaluation of losartan (LOS) and amlodipine besylate (AML). Method I is based on measuring second-derivative synchronous fluorescence spectra of LOS and AML at Δ<i>λ</i> = 80 nm in water. The experimental factors influencing the synchronous fluorescence of the considered compounds were sensibly adjusted. The chromatographic analysis was executed on a Nucleodur MN-C18 column of dimensions; 250 mm × 4.6 mm i.d. and 5 µm particle size). The fluorimetric detection was time-programmed at <i>λ</i>em = 440 nm for AML (0.0–7.5 min) and at <i>λ</i>em = 400 nm for LOS (7.5–10 min) after excitation at <i>λ</i> ex = 245 nm. The mobile phase is a blend of acetonitrile with 0.02 M phosphate buffer in...

S1: Effect of different types of organized media on AML (2µg / mL) and LOS (2µg / mL). S2: Effect of diluting solvents on AML (2µg / mL) and LOS (2µg / mL). S3: Effect of pH on AML (2µg / mL) and LOS (2µg / mL). from Simultaneous evaluation of losartan and amlodipine besylate using second-derivat...

This study is concerned with two sensitive, fast and reproducible approaches; namely, second-deri... more This study is concerned with two sensitive, fast and reproducible approaches; namely, second-derivative synchronous fluorimetry (method I) and reversed phase high-performance liquid chromatography with fluorimetric detection (method II) for synchronized evaluation of losartan (LOS) and amlodipine besylate (AML). Method I is based on measuring second-derivative synchronous fluorescence spectra of LOS and AML at Δ<i>λ</i> = 80 nm in water. The experimental factors influencing the synchronous fluorescence of the considered compounds were sensibly adjusted. The chromatographic analysis was executed on a Nucleodur MN-C18 column of dimensions; 250 mm × 4.6 mm i.d. and 5 µm particle size). The fluorimetric detection was time-programmed at <i>λ</i>em = 440 nm for AML (0.0–7.5 min) and at <i>λ</i>em = 400 nm for LOS (7.5–10 min) after excitation at <i>λ</i> ex = 245 nm. The mobile phase is a blend of acetonitrile with 0.02 M phosphate buffer in...

Simultaneous estimation of amlodipine and atorvastatin by micelle-augmented first derivative synchronous spectrofluorimetry and multivariate analysis

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

Five Selective, rapid and sensitive spectrofluorimetric methods were performed in this study for ... more Five Selective, rapid and sensitive spectrofluorimetric methods were performed in this study for the simultaneous estimation of amlodipine besylate (AML) and atorvastatin (ATR) in their binary mixtures and combination polypills that are used for management of cardiovascular conditions. The first method depends on micelle-enhanced first derivative synchronous fluorimetric analysis (method I) and the other four methods are multivariate analysis techniques based on the use of factor-based calibration prediction methods comprising partial least squares (PLS), Principal Component Regression (PCR), genetic algorithm PLS (GA-PLS) and genetic algorithm PCR (GA-PCR). The synchronous fluorescence spectra of the solutions were measured at a constant wavelength difference; Δλ = 100 nm. The magnitudes of the peaks of the first derivative spectra (1D) were measured at 292 nm and 387 nm for ATR, and AML correspondingly. The multivariate models were constructed utilizing fifteen mixtures as a calibration set and ten mixtures as a validation set. The linearity of all the methods was in the concentration ranges of (0.1-4.0 μg mL-1, 0.4-10.0 μg mL-1) for AML and ATR, correspondingly. Statistical analysis revealed no significant difference between the proposed methods and the reference method. The validity of the proposed methods allows their suitability for quality control work. All the analysis settings were optimized and all the suggested procedures were applied productively for the determination of both drugs in synthetic mixtures, validation set, and combination polypills.

Simultaneous determination of tylosin and josamycin residues in muscles, liver, eggs and milk by MLC with a monolithic column and time-programmed UV detection: application to baby food and formulae

Chemistry Central Journal, 2014

Background: Tylosin and Josamycin are macrolide antibiotics. They are used in the treatment of pn... more Background: Tylosin and Josamycin are macrolide antibiotics. They are used in the treatment of pneumonia, arthritis and mastitis in cattle, and mycoplasma infections in poultry. The incorrect use of antibiotics has lead to the presence of antibiotic residues in foods. The residues cause toxic effects on consumers. Results: A simple and sensitive method was optimized and validated for the analysis of tylosin and josamycin residues in food samples. Analytical separation was performed in less than 10 min using a RP C 18 monolithic column with time-programmed UV detection at 287 nm and 232 nm and a micellar solution of 0.17 M sodium dodecyl sulphate, 14% methanol and 0.3% triethylamine in 0.02 M phosphoric acid buffered at pH 4 as the mobile phase. The method was fully validated in accordance with ICH guidelines. The micellar method was successfully applied to quantitatively determine tylosin and josamycin residues in spiked chicken muscles, chicken liver, bovine muscles, liver, milk and eggs. It was also extended to the determination of tylosin and josamycin residues in chicken-based baby food and baby formulae. The compounds were separated by a monolithic column which, on account of its particular structure, could bear higher flow rates than usually found for this kind of analysis. High extraction efficiency for tylosin and josamycin was obtained without matrix interference in the extraction process and in the subsequent chromatographic determination. No organic solvent was used during the pretreatment step. Hence, it is considered an interesting technique for "green" chemistry. Conclusion: The proposed method was validated and successfully applied for the determination of tylosin and josamycin residues in spiked chicken muscles, chicken liver, bovine muscles, liver, milk and eggs. It was also extended to the determination of tylosin and josamycin residues in chicken-based baby food and baby formulae.

Determination of Carbadox and Olaquindox Residues in Chicken Muscles, Chicken Liver, Bovine Meat, Liver and Milk by MLC with UV Detection: Application to Baby Formulae

Chromatographia, 2013

A simple and sensitive method was optimized and validated for the analysis of carbadox and olaqui... more A simple and sensitive method was optimized and validated for the analysis of carbadox and olaquindox residues in chicken muscles, chicken liver, bovine meat, liver and milk. Analytical separation was performed in less than 4 min using a C18 column with UV detection at 373 nm and a micellar solution of 0.1 M sodium dodecyl sulphate, 10 % acetonitrile and 0.3 % triethylamine in 0.02 M phosphoric acid buffered at pH 4 as the mobile phase. The method was fully validated in accordance with ICH guidelines. The micellar method was successfully applied to quantitatively determine carbadox and olaquindox residues in spiked chicken muscles, chicken liver, bovine meat, liver and milk. It was also extended to the determination of carbadox and olaquindox residues in baby formulae. The recoveries obtained were in the 89.2–93.6 and 93.0–107.2 % ranges for carbadox and olaquindox, respectively. High extraction efficiency for carbadox and olaquindox was obtained without matrix interference in the extraction process and in the subsequent chromatographic determination. No organic solvent was used during the pretreatment step.

Spectrophotometric determination of fenoterol hydrobromide in pure form and dosage forms

Il Farmaco, 2003

A sensitive and rapid spectrophotometric procedure has been investigated for the determination of... more A sensitive and rapid spectrophotometric procedure has been investigated for the determination of fenoterol either per se or in pharmaceutical preparations. The proposed procedure is based on the reaction between the drug and 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) at pH 7.2, using borate buffer, to produce a yellow adduct. The latter has maximum absorbance at 400 nm and obeys Beer&#39;s law within the concentration range 5-30 microg/ml. Regression analysis of the calibration data showed a good correlation coefficient (r=0.9996) with minimum detection limit of 0.24 microg/ml (6.2 x 10(-8) M). The proposed procedure has been successfully applied to the determination of this drug in its tablets and in syrup, the mean percent recoveries were 97.45+/-0.59 and 98.7+/-0.64%, respectively. The results obtained are in good agreement with those given using a reference method. The pharmaceutical additives other than active ingredient did not interfere. A proposal of the reaction pathway has been postulated.

Validated Sensitive Spectrophotometric methods for Determination of Carvedilol and Nebivolol HCl in dosage forms

A simple, sensitive and rapid spectrophotometric methods were developed and validated for the det... more A simple, sensitive and rapid spectrophotometric methods were developed and validated for the determination of two antihypertensive drugs namely, carvedilol and nebivolol hydrochloride in pure form and pharmaceutical formulations. Method (I) is based on the formation of a binary complex between the studied drugs and eosin Y in presence of tween 80 at (pH 3.0).The formed complex exhibited maximum absorption at 545 nm for carvedilol and 543 nm for nebivolol. The concentration plots were rectilinear over concentration range of 0.5-5 and 1-7 µg/mL with lower detection limits of 0.09 and 0.11µg/mL and lower quantitation limits of 0.28 and 0.34 µg/mL for carvedilol and nebivolol respectively. Method (II) is based on the reaction of studied drugs through their secondary amino groups with 2, 4-dinitrofluorobenzene (DNFB) at pH 8 to form yellow colored reaction products peaking at 383 nm and 390 nm for carvedilol and nebivolol, respectively. The absorbance-concentration plots were rectilinea...

RESEARCH ARTICLE Open Access Simultaneous determination of sulpiride and

mebeverine by HPLC method using fluorescence detection: application to real human plasma

RESEARCH ARTICLE Open Access Simultaneous determination of tylosin and

josamycin residues in muscles, liver, eggs and milk by MLC with a monolithic column and tection: ... more

Facile approaches for determination of Bromhexine Hydrochloride and its active metabolite Ambroxol Hydrochloride using Eosin Y

Annales Pharmaceutiques Françaises

Spectrophotometric Methods for Simultaneous Determination of Rivaroxaban and Clopidogrel in Their Binary Mixture

Pharmaceutica Analytica Acta, 2017

Three rapid, accurate and very simple derivative spectrophotometric methods for RIV and CLP assay... more Three rapid, accurate and very simple derivative spectrophotometric methods for RIV and CLP assay in their binary mixture and tablet dosage forms were developed. Method (I) is first derivative spectrophotometric method, derivative amplitudes were measured at the zero crossing wavelength of 289 and 249.5 nm for estimation of RIV and CLP, respectively. The linearity is over the range 2.0 - 20.0 μg/ml for RIV and 5.0 - 60.0 μg/ml for CLP with LOD of 0.211 and 0.361 μg mL-1 and LOQ of 0.641 and 1.095 μg mL-1 for RIV and CLP, respectively. Method (II) is ratio derivative spectrophotometric method. The ratio spectra of each drug were derived by dividing its spectra on a constant concentration of the other drug as a divisor. Derivative amplitudes were measured at 256 nm for RIV and at 214.5 nm for CLP over the same linearity range as the first method with LOD of 0.137 and 0.485 μg mL-1 and LOQ of 0.417 and 1.471 μg mL-1 for RIV and CLP, respectively. Method (III) is absorbance ratio method...

New spectroscopic methods for determination of dexlansoprazole using mercurochrome

Luminescence : the journal of biological and chemical luminescence, 2021

New spectroscopic methods have been developed for dexlansoprazole estimation in capsule formulati... more New spectroscopic methods have been developed for dexlansoprazole estimation in capsule formulation based on formation of reaction between dexalnsoprazole and mercurochrome (MER) at pH 3.7. The formed complex was measured spectrophotometrically (Method I) at 557 nm and Spectrofluorometrically (Method II) at 300/538 nm, because the drug caused quantitative quenching on the native fluorescence of mercurochrome. The spectrophotometric method was linear over the concentration of 25 to 55 μg/mL with LOD of 1.15 μg/ml and LOQ of 3.48 μg/ml. The spectrofluorometric one having a linear range of 20 to 45 μg/mL with LOD of 1.13 μg/mL and LOQ of 3.45 μg/ml. The methods suggested were utilized to analyze capsules to test interferences from excipients and the data indicated good selectivity. Data obtained were statistically analysed and were favourably good. The new methods are environmentally benign depending on distilled water mainly as diluting solvent. This property was confirmed by assessin...

Factorial design-assisted reversed phase-high performance liquid chromatography method for simultaneous determination of fluconazole, itraconazole and terbinafine

A 23 full factorial design model was used for the development of a new high performance liquid ch... more A 23 full factorial design model was used for the development of a new high performance liquid chromatography method with UV detection to estimate three antifungal drugs simultaneously. Fluconazole (FLU), itraconazole (ITR) and terbinafine (TRH) are co-administered for severe fungal infections. They have been determined using MOS-1 Hypersil C18 column and an isocratic eluent; methanol 95% and phosphate buffer 5% with 0.001% triethylamine. The pH was adjusted to 7, and the flow rate was 0.7 ml min−1. The three drugs were separated within less than 7 min at 210 nm. The developed method gave a linear response over 5–80 µg ml−1, 5–50 µg ml−1 and 1–50 µg ml−1 for FLU, ITR and TRH, respectively. It showed detection limits of 0.88, 0.29 and 0.20 µg ml−1 and quantification limits of 2.66, 0.88 and 0.60 µg ml−1 for the three drugs, respectively. The design of the experiment facilitated the optimization of different variables affecting the separation of the three drugs. The sensitivity of the...

Utilization of a Micellar Matrix for Simultaneous Spectrofluorimetric Estimation of Alfuzosin Hydrochloride and Vardenafil Hydrochloride

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

Utilization of Localized Surface Plasmon Resonance of Silver Nanoparticles for the Spectrofluorimetric Estimation of Oxymetazoline in Dosage Forms: Application to Aqueous Humor

Journal of Fluorescence

Conventional and synchronous spectrofluorometric determination of the recently administered drugs for treatment of COVID-19 favipiravir and apixaban

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...

Inspection of antimicrobial remains in bovine milk in Egypt and Saudi Arabia employing a bacteriological test kit and HPLC-MS/MS with estimation of risk to human health

PLOS ONE, 2022

Veterinary medicine uses antibiotics randomly for treatment and growth promotion. Milk of dairy a... more Veterinary medicine uses antibiotics randomly for treatment and growth promotion. Milk of dairy animals contains substantial quantities of antibiotics that have harmful effects on health. It is therefore necessary to test commercially available milk using immunological, chromatographic, or microbiological methods to confirm the absence of antibiotic residues. This study aims to perform a microbiological test, followed by a quantitative confirmation analysis, on raw milk to assess the presence of antibiotic residues. Tests were conducted on 200 milk samples collected from markets and farms in Saudi Arabia and Egypt. The microbial inhibitor test (Delvotest SP-NT) revealed that 40 samples were positive for antibiotic residues. The positive samples were further tested using liquid chromatography-tandem mass spectrometry (LC-MS/MS) as a confirmatory quantitative test for 29 antibiotics that belong to five groups: tetracyclines, sulfonamides, fluoroquinolones, macrolides, and lactamases. Only four samples tested positive for oxytetracycline residues above the maximum residue limit. Based on these results, researchers suggest a monitoring system that considers both microbial and HPLC-MS/MS methods when detecting antibiotic residues in bovine milk. The analysis of risk to human health revealed that antibiotic residues at the detected levels do not pose any health risks to consumers.

A synchronous spectrofluorometric technique for simultaneous detection of alfuzosin and tadalafil: applied to tablets and spiked biological samples

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 Δ λ = 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...

Utilization of N,S‐Doped Carbon Dots as a Fluorescent Nanosensor for Determination of Cromolyn Based on Inner Filter Effect; Application to Aqueous Humor

Luminescence, 2022

A simple and eco-friendly hydrothermal technique is used to prepare water soluble N and S co-dope... more A simple and eco-friendly hydrothermal technique is used to prepare water soluble N and S co-doped carbon quantum dots probe (N,S-CQDs) from thiosemicarbazide and citric acid. Several characterization techniques were performed in order to ensure well- synthesis of highly luminescent N,S-CQDs. The prepared probe exhibited analytical potential as optical nanosensor for the spectrofluorimetric determination of cromolyn sodium (CRO) in its pharmaceutical dosage forms and aqueous humor. The emission intensity of the synthesized N,S-CQDs was measured at 411 nm after excitation at 345 nm. Addition of increasing concentrations of CRO to N,S-CQDs led to quenching of its fluorescence intensity. CRO was investigated within wide concentration range of 10.0 to 150.0 μM with limit of detection of 2.0 μM and limit of quantification of 6.0 μM. The quenching of fluorescent N,S-CQDs occurs through inner filter effect (IFE). The developed spectrofluorimetric method was successfully optimized and validated according to International Council of Harmonization (ICH). Method greenness is proved through using both Eco-scale and AGREE approaches.

Use of Green-Modified Micellar Liquid Chromatography For the Determination of Imidocarb Dipropionate Residues in Food Samples

Microchemical Journal

Supplementary material from "Simultaneous evaluation of losartan and amlodipine besylate using second-derivative synchronous spectrofluorimetric technique and liquid chromatography with time-programmed fluorimetric detection

This study is concerned with two sensitive, fast and reproducible approaches; namely, second-deri... more This study is concerned with two sensitive, fast and reproducible approaches; namely, second-derivative synchronous fluorimetry (method I) and reversed phase high-performance liquid chromatography with fluorimetric detection (method II) for synchronized evaluation of losartan (LOS) and amlodipine besylate (AML). Method I is based on measuring second-derivative synchronous fluorescence spectra of LOS and AML at Δ<i>λ</i> = 80 nm in water. The experimental factors influencing the synchronous fluorescence of the considered compounds were sensibly adjusted. The chromatographic analysis was executed on a Nucleodur MN-C18 column of dimensions; 250 mm × 4.6 mm i.d. and 5 µm particle size). The fluorimetric detection was time-programmed at <i>λ</i>em = 440 nm for AML (0.0–7.5 min) and at <i>λ</i>em = 400 nm for LOS (7.5–10 min) after excitation at <i>λ</i> ex = 245 nm. The mobile phase is a blend of acetonitrile with 0.02 M phosphate buffer in...

S1: Effect of different types of organized media on AML (2µg / mL) and LOS (2µg / mL). S2: Effect of diluting solvents on AML (2µg / mL) and LOS (2µg / mL). S3: Effect of pH on AML (2µg / mL) and LOS (2µg / mL). from Simultaneous evaluation of losartan and amlodipine besylate using second-derivat...

This study is concerned with two sensitive, fast and reproducible approaches; namely, second-deri... more This study is concerned with two sensitive, fast and reproducible approaches; namely, second-derivative synchronous fluorimetry (method I) and reversed phase high-performance liquid chromatography with fluorimetric detection (method II) for synchronized evaluation of losartan (LOS) and amlodipine besylate (AML). Method I is based on measuring second-derivative synchronous fluorescence spectra of LOS and AML at Δ<i>λ</i> = 80 nm in water. The experimental factors influencing the synchronous fluorescence of the considered compounds were sensibly adjusted. The chromatographic analysis was executed on a Nucleodur MN-C18 column of dimensions; 250 mm × 4.6 mm i.d. and 5 µm particle size). The fluorimetric detection was time-programmed at <i>λ</i>em = 440 nm for AML (0.0–7.5 min) and at <i>λ</i>em = 400 nm for LOS (7.5–10 min) after excitation at <i>λ</i> ex = 245 nm. The mobile phase is a blend of acetonitrile with 0.02 M phosphate buffer in...

Simultaneous estimation of amlodipine and atorvastatin by micelle-augmented first derivative synchronous spectrofluorimetry and multivariate analysis

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

Five Selective, rapid and sensitive spectrofluorimetric methods were performed in this study for ... more Five Selective, rapid and sensitive spectrofluorimetric methods were performed in this study for the simultaneous estimation of amlodipine besylate (AML) and atorvastatin (ATR) in their binary mixtures and combination polypills that are used for management of cardiovascular conditions. The first method depends on micelle-enhanced first derivative synchronous fluorimetric analysis (method I) and the other four methods are multivariate analysis techniques based on the use of factor-based calibration prediction methods comprising partial least squares (PLS), Principal Component Regression (PCR), genetic algorithm PLS (GA-PLS) and genetic algorithm PCR (GA-PCR). The synchronous fluorescence spectra of the solutions were measured at a constant wavelength difference; Δλ = 100 nm. The magnitudes of the peaks of the first derivative spectra (1D) were measured at 292 nm and 387 nm for ATR, and AML correspondingly. The multivariate models were constructed utilizing fifteen mixtures as a calibration set and ten mixtures as a validation set. The linearity of all the methods was in the concentration ranges of (0.1-4.0 μg mL-1, 0.4-10.0 μg mL-1) for AML and ATR, correspondingly. Statistical analysis revealed no significant difference between the proposed methods and the reference method. The validity of the proposed methods allows their suitability for quality control work. All the analysis settings were optimized and all the suggested procedures were applied productively for the determination of both drugs in synthetic mixtures, validation set, and combination polypills.

Simultaneous determination of tylosin and josamycin residues in muscles, liver, eggs and milk by MLC with a monolithic column and time-programmed UV detection: application to baby food and formulae

Chemistry Central Journal, 2014

Background: Tylosin and Josamycin are macrolide antibiotics. They are used in the treatment of pn... more Background: Tylosin and Josamycin are macrolide antibiotics. They are used in the treatment of pneumonia, arthritis and mastitis in cattle, and mycoplasma infections in poultry. The incorrect use of antibiotics has lead to the presence of antibiotic residues in foods. The residues cause toxic effects on consumers. Results: A simple and sensitive method was optimized and validated for the analysis of tylosin and josamycin residues in food samples. Analytical separation was performed in less than 10 min using a RP C 18 monolithic column with time-programmed UV detection at 287 nm and 232 nm and a micellar solution of 0.17 M sodium dodecyl sulphate, 14% methanol and 0.3% triethylamine in 0.02 M phosphoric acid buffered at pH 4 as the mobile phase. The method was fully validated in accordance with ICH guidelines. The micellar method was successfully applied to quantitatively determine tylosin and josamycin residues in spiked chicken muscles, chicken liver, bovine muscles, liver, milk and eggs. It was also extended to the determination of tylosin and josamycin residues in chicken-based baby food and baby formulae. The compounds were separated by a monolithic column which, on account of its particular structure, could bear higher flow rates than usually found for this kind of analysis. High extraction efficiency for tylosin and josamycin was obtained without matrix interference in the extraction process and in the subsequent chromatographic determination. No organic solvent was used during the pretreatment step. Hence, it is considered an interesting technique for "green" chemistry. Conclusion: The proposed method was validated and successfully applied for the determination of tylosin and josamycin residues in spiked chicken muscles, chicken liver, bovine muscles, liver, milk and eggs. It was also extended to the determination of tylosin and josamycin residues in chicken-based baby food and baby formulae.

Determination of Carbadox and Olaquindox Residues in Chicken Muscles, Chicken Liver, Bovine Meat, Liver and Milk by MLC with UV Detection: Application to Baby Formulae

Chromatographia, 2013

A simple and sensitive method was optimized and validated for the analysis of carbadox and olaqui... more A simple and sensitive method was optimized and validated for the analysis of carbadox and olaquindox residues in chicken muscles, chicken liver, bovine meat, liver and milk. Analytical separation was performed in less than 4 min using a C18 column with UV detection at 373 nm and a micellar solution of 0.1 M sodium dodecyl sulphate, 10 % acetonitrile and 0.3 % triethylamine in 0.02 M phosphoric acid buffered at pH 4 as the mobile phase. The method was fully validated in accordance with ICH guidelines. The micellar method was successfully applied to quantitatively determine carbadox and olaquindox residues in spiked chicken muscles, chicken liver, bovine meat, liver and milk. It was also extended to the determination of carbadox and olaquindox residues in baby formulae. The recoveries obtained were in the 89.2–93.6 and 93.0–107.2 % ranges for carbadox and olaquindox, respectively. High extraction efficiency for carbadox and olaquindox was obtained without matrix interference in the extraction process and in the subsequent chromatographic determination. No organic solvent was used during the pretreatment step.

Spectrophotometric determination of fenoterol hydrobromide in pure form and dosage forms

Il Farmaco, 2003

A sensitive and rapid spectrophotometric procedure has been investigated for the determination of... more A sensitive and rapid spectrophotometric procedure has been investigated for the determination of fenoterol either per se or in pharmaceutical preparations. The proposed procedure is based on the reaction between the drug and 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) at pH 7.2, using borate buffer, to produce a yellow adduct. The latter has maximum absorbance at 400 nm and obeys Beer&#39;s law within the concentration range 5-30 microg/ml. Regression analysis of the calibration data showed a good correlation coefficient (r=0.9996) with minimum detection limit of 0.24 microg/ml (6.2 x 10(-8) M). The proposed procedure has been successfully applied to the determination of this drug in its tablets and in syrup, the mean percent recoveries were 97.45+/-0.59 and 98.7+/-0.64%, respectively. The results obtained are in good agreement with those given using a reference method. The pharmaceutical additives other than active ingredient did not interfere. A proposal of the reaction pathway has been postulated.

Validated Sensitive Spectrophotometric methods for Determination of Carvedilol and Nebivolol HCl in dosage forms

A simple, sensitive and rapid spectrophotometric methods were developed and validated for the det... more A simple, sensitive and rapid spectrophotometric methods were developed and validated for the determination of two antihypertensive drugs namely, carvedilol and nebivolol hydrochloride in pure form and pharmaceutical formulations. Method (I) is based on the formation of a binary complex between the studied drugs and eosin Y in presence of tween 80 at (pH 3.0).The formed complex exhibited maximum absorption at 545 nm for carvedilol and 543 nm for nebivolol. The concentration plots were rectilinear over concentration range of 0.5-5 and 1-7 µg/mL with lower detection limits of 0.09 and 0.11µg/mL and lower quantitation limits of 0.28 and 0.34 µg/mL for carvedilol and nebivolol respectively. Method (II) is based on the reaction of studied drugs through their secondary amino groups with 2, 4-dinitrofluorobenzene (DNFB) at pH 8 to form yellow colored reaction products peaking at 383 nm and 390 nm for carvedilol and nebivolol, respectively. The absorbance-concentration plots were rectilinea...

RESEARCH ARTICLE Open Access Simultaneous determination of sulpiride and

mebeverine by HPLC method using fluorescence detection: application to real human plasma

RESEARCH ARTICLE Open Access Simultaneous determination of tylosin and

josamycin residues in muscles, liver, eggs and milk by MLC with a monolithic column and tection: ... more

Facile approaches for determination of Bromhexine Hydrochloride and its active metabolite Ambroxol Hydrochloride using Eosin Y

Annales Pharmaceutiques Françaises

Spectrophotometric Methods for Simultaneous Determination of Rivaroxaban and Clopidogrel in Their Binary Mixture

Pharmaceutica Analytica Acta, 2017

Three rapid, accurate and very simple derivative spectrophotometric methods for RIV and CLP assay... more Three rapid, accurate and very simple derivative spectrophotometric methods for RIV and CLP assay in their binary mixture and tablet dosage forms were developed. Method (I) is first derivative spectrophotometric method, derivative amplitudes were measured at the zero crossing wavelength of 289 and 249.5 nm for estimation of RIV and CLP, respectively. The linearity is over the range 2.0 - 20.0 μg/ml for RIV and 5.0 - 60.0 μg/ml for CLP with LOD of 0.211 and 0.361 μg mL-1 and LOQ of 0.641 and 1.095 μg mL-1 for RIV and CLP, respectively. Method (II) is ratio derivative spectrophotometric method. The ratio spectra of each drug were derived by dividing its spectra on a constant concentration of the other drug as a divisor. Derivative amplitudes were measured at 256 nm for RIV and at 214.5 nm for CLP over the same linearity range as the first method with LOD of 0.137 and 0.485 μg mL-1 and LOQ of 0.417 and 1.471 μg mL-1 for RIV and CLP, respectively. Method (III) is absorbance ratio method...

New spectroscopic methods for determination of dexlansoprazole using mercurochrome

Luminescence : the journal of biological and chemical luminescence, 2021

New spectroscopic methods have been developed for dexlansoprazole estimation in capsule formulati... more New spectroscopic methods have been developed for dexlansoprazole estimation in capsule formulation based on formation of reaction between dexalnsoprazole and mercurochrome (MER) at pH 3.7. The formed complex was measured spectrophotometrically (Method I) at 557 nm and Spectrofluorometrically (Method II) at 300/538 nm, because the drug caused quantitative quenching on the native fluorescence of mercurochrome. The spectrophotometric method was linear over the concentration of 25 to 55 μg/mL with LOD of 1.15 μg/ml and LOQ of 3.48 μg/ml. The spectrofluorometric one having a linear range of 20 to 45 μg/mL with LOD of 1.13 μg/mL and LOQ of 3.45 μg/ml. The methods suggested were utilized to analyze capsules to test interferences from excipients and the data indicated good selectivity. Data obtained were statistically analysed and were favourably good. The new methods are environmentally benign depending on distilled water mainly as diluting solvent. This property was confirmed by assessin...

Factorial design-assisted reversed phase-high performance liquid chromatography method for simultaneous determination of fluconazole, itraconazole and terbinafine

A 23 full factorial design model was used for the development of a new high performance liquid ch... more A 23 full factorial design model was used for the development of a new high performance liquid chromatography method with UV detection to estimate three antifungal drugs simultaneously. Fluconazole (FLU), itraconazole (ITR) and terbinafine (TRH) are co-administered for severe fungal infections. They have been determined using MOS-1 Hypersil C18 column and an isocratic eluent; methanol 95% and phosphate buffer 5% with 0.001% triethylamine. The pH was adjusted to 7, and the flow rate was 0.7 ml min−1. The three drugs were separated within less than 7 min at 210 nm. The developed method gave a linear response over 5–80 µg ml−1, 5–50 µg ml−1 and 1–50 µg ml−1 for FLU, ITR and TRH, respectively. It showed detection limits of 0.88, 0.29 and 0.20 µg ml−1 and quantification limits of 2.66, 0.88 and 0.60 µg ml−1 for the three drugs, respectively. The design of the experiment facilitated the optimization of different variables affecting the separation of the three drugs. The sensitivity of the...

Utilization of a Micellar Matrix for Simultaneous Spectrofluorimetric Estimation of Alfuzosin Hydrochloride and Vardenafil Hydrochloride

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

Utilization of Localized Surface Plasmon Resonance of Silver Nanoparticles for the Spectrofluorimetric Estimation of Oxymetazoline in Dosage Forms: Application to Aqueous Humor

Journal of Fluorescence