Maha Hegazy | Cairo University (original) (raw)

Papers by Maha Hegazy

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2015

The resolving power of spectrophotometric assisted mathematical techniques were demonstrated for ... more The resolving power of spectrophotometric assisted mathematical techniques were demonstrated for the simultaneous determination of perindopril arginin (PER) and amlodipine besylate (AML) in presence of their degradation products. The conventional univariate methods include the absorptivity factor method (AFM) and absorption correction method (ACM), which were able to determine the two drugs, simultaneously, but not in the presence of their degradation products. In both methods, amlodipine was determined directly at 360nm in the concentration range of 8-28μgmL(-1), on the other hand perindopril was determined by AFM at 222.2nm and by ACM at 208nm in the concentration range of 10-70μgmL(-1). Moreover, the applied multivariate calibration methods were able for the determination of perindopril and amlodipine in presence of their degradation products using concentration residuals augmented classical least squares (CRACLS) and partial least squares (PLS). The proposed multivariate methods were applied to 19 synthetic samples in the concentration ranges of 60-100μgmL(-1) perindopril and 20-40μgmL(-1) amlodipine. Commercially available tablet formulations were successfully analysed using the developed methods without interference from other dosage form additives except PLS model, which failed to determine both drugs in their pharmaceutical dosage form.

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, Jan 5, 2015

Smart and novel spectrophotometric and chemometric methods have been developed and validated for ... more Smart and novel spectrophotometric and chemometric methods have been developed and validated for the simultaneous determination of a binary mixture of chloramphenicol (CPL) and dexamethasone sodium phosphate (DSP) in presence of interfering substances without prior separation. The first method depends upon derivative subtraction coupled with constant multiplication. The second one is ratio difference method at optimum wavelengths which were selected after applying derivative transformation method via multiplying by a decoding spectrum in order to cancel the contribution of non labeled interfering substances. The third method relies on partial least squares with regression model updating. They are so simple that they do not require any preliminary separation steps. Accuracy, precision and linearity ranges of these methods were determined. Moreover, specificity was assessed by analyzing synthetic mixtures of both drugs. The proposed methods were successfully applied for analysis of bo...

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2015

Two methods are developed for simultaneous estimation of paracetamol, domperidone and tramadol HC... more Two methods are developed for simultaneous estimation of paracetamol, domperidone and tramadol HCl in pure and tablet dosage form by using 0.1N NaOH as a solvent. Paracetamol, domperidone and tramadol HCl show absorbance maximums at 256 nm, 289.6 nm and 218.4 nm respectively. Shimadzu UV 1700, capable of multicomponent analysis, was used for quantitation. In method I, absorbance of the sample solution was measured at 256 nm and 289.6 nm for the estimation of paracetamol, domperidone respectively as tramadol HCl does not absorb at these wavelengths. Estimation of tramadol HCl was carried out at 218.4 nm. Method II is based on a multiwavelength spectroscopic method. Validation study reveals that the methods are specific, accurate, precise, and reproducible. All three drugs obey Beer's law in the concentration ranges used for the methods. Validation studies are statistically significant as all the statistical parameters are within the acceptance range (% COV< 2.0 and S.D. < 2.0) for both accuracy and precision study. High recovery and low % COV reveals the reliability of the method for quantitative study of three drugs in tablet formulation. The methods are simple, rapid accurate, precise, reproducible, and economic and can be used for routine quantitative analysis of paracetamol, domperidone and tramadol HCl in pure and tablet dosage form.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2015

This work is concerned with development and validation of three simple, specific, accurate and pr... more This work is concerned with development and validation of three simple, specific, accurate and precise spectrophotometric methods for determination of flumethasone pivalate (FP) and clioquinol (CL) in their binary mixture and ear drops. Method A is a ratio subtraction spectrophotometric one (RSM). Method B is a ratio difference spectrophotometric one (RDSM), while method C is a mean center spectrophotometric one (MCR). The calibration curves are linear over the concentration range of 3-45 μg/mL for FP, and 2-25 μg/mL for CL. The specificity of the developed methods was assessed by analyzing different laboratory prepared mixtures of the FP and CL. The three methods were validated as per ICH guidelines; accuracy, precision and repeatability are found to be within the acceptable limits.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2015

Journal of Pharmaceutical Analysis, 2014

Determination of a novel ACE inhibitor in the presence of alkaline and oxidative degradation prod... more Determination of a novel ACE inhibitor in the presence of alkaline and oxidative degradation products using smart spectrophotometric and chemometric methods, Journal of Pharmaceutical Analysis, http: //dx.

Talanta, 2014

Imidapril hydrochloride (IMD) is a recently developed prodrug-type angiotensin-converting enzyme ... more Imidapril hydrochloride (IMD) is a recently developed prodrug-type angiotensin-converting enzyme (ACE) inhibitor. Due to its instability under both hydrolytic and oxidative conditions, development of rapid, simple and sensitive methods for its determination in the presence of its possible degradation products is essential. We proposed two simple liquid chromatographic methods associated with ultraviolet detection. The first method is an HPTLC-densitometric one in which separation of IMD from its degradation products was achieved followed by densitometric scanning at 220 nm using silica gel F 254 plates and chloroform:ethanol:acetic acid (3:0.5:0.1, v/v/v) as the developing system. The second method was based on RP-HPLC in which the separation was performed using C18 analytical column and isocratic elution system with acetonitrile: 0.15% triethylamine (pH ¼2.2) (40:60, v/v). The optimum flow rate was 1.5 mL min À 1 and the detection was at 220 nm. Validation was conducted in compliance with the ICH guidelines and the methods were successfully applied for IMD determination in its commercial tablets. The obtained results were statistically compared to those obtained by applying reported HPLC method where no significant difference was found in accordance with accuracy and precision.

Talanta, 2010

Simple, accurate, sensitive and validated UV spectrophotometric, chemometric and HPTLC-densitomet... more Simple, accurate, sensitive and validated UV spectrophotometric, chemometric and HPTLC-densitometric methods were developed for determination of oxybutynin hydrochloride (OX) in presence of its degradation product and additives in its pharmaceutical formulations. Method A is the first derivative of ratio spectra (DD(1)) which allows the determination of OX in presence of its degradate in pure form and tablets by measuring the peaks amplitude at 216 nm. Method B and C are principal component regression (PCR) and partial least-squares (PLS) for determination of OX in presence of its degradate in pure form, tablets and syrup. While, the developed high performance thin layer chromatography HPTLC-densitometric method was based on the separation of OX from its degradation product, methylparaben and propylparaben followed by densitometric measurement at 220 nm which allows the determination of OX in pure form, tablets and syrup. The separation was achieved using HPTLC silica gel F(254) plates and chloroform:methanol:ammonia solution:triethylamine (100:3:0.5:0.2, v/v/v/v) as the developing system. The accuracy, precision and linearity ranges of the developed methods were determined. The results obtained were statistically compared with each other and to that of a reported HPLC method, and there was no significant difference between the proposed methods and the reported method regarding both accuracy and precision.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014

Materials Chemistry and Physics, 2010

A series of alkyl dimethylisopropylammonium hydroxide cationic surfactants (DEDIAOH, DODIAOH and ... more A series of alkyl dimethylisopropylammonium hydroxide cationic surfactants (DEDIAOH, DODIAOH and HEDIAOH) was synthesized and characterized. The surface properties such as the critical micelle concentration (CMC), the effectiveness of surface tension reduction (˘C MC ), surface excess concentration ( max ) and surface area per molecule (A min ) have been determined by means of surface tension measurements. The degree of counter ion dissociation (ˇ) and the free energy of micellization ( G mic ) were calculated. The corrosion inhibition of the synthesized cationic surfactants on carbon steel surface in 1 M HCl solution was investigated. For this purpose, a series of techniques such as gravimetric measurement, potentiodynamic polarization and scanning electron microscope (SEM) were used. The values of activation energy for carbon steel corrosion and the thermodynamic parameters such as adsorption equilibrium constant (K ads ), free energy of adsorption ( G • ads ), adsorption heat ( H • ads ) and adsorption entropy ( S • ads ) values were evaluated. Results showed that HEDIAOH had better inhibition effect than DEDIAOH and DODIAOH of the corrosion of carbon steel in 1 M HCl solution and inhibition efficiency is higher than 96% after 24 h at 1 × 10 −2 M concentration of the inhibitor. The inhibition efficiency is discussed in terms of strong adsorption of the inhibitor molecules on the metal surface and formation of a protective film. Scanning electron microscope (SEM) showed a good surface coverage on the metal surface. The Biological activity was examined against sulfate reducing bacteria (SRB) by dilution method.

Journal of Dispersion Science and Technology, 2012

In this paper, three deferent surfactants as corrosion inhibitor were prepared in two steps; In t... more In this paper, three deferent surfactants as corrosion inhibitor were prepared in two steps; In the first step, maleic anhydride was amidated with dodecylamine to produce polyoxy ethylenyl-2-ene-4-dodecanamide butanoic acid. In the second step, the resulting product was further was further esterified with different molecular weights of polyethylene glycol (m. wt. = 200, 400 and 600) namely; MP2, MP4 and MP6. The

Journal of Chromatographic Science, 2013

A simple and sensitive stability indicating HPLC method was developed and validated for quantitat... more A simple and sensitive stability indicating HPLC method was developed and validated for quantitative determination of Nitazoxanide (NTZ), a new antiprotozoal drug, in presence of degradation products generated under forced alkaline hydrolysis. Chromatographic separation was achieved on Inertsil C8-3 column (150 3 4.6 mm i.d.) using a mobile phase composed of acetonitrile: 50 mM ammonium acetate buffer (50:50, v/v, pH 5.0 adjusted with acetic acid) at a flow rate of 1 mL/min. Quantification was achieved with UV detection at 298 nm based on relative peak area. The method was linear over the concentration range of 0.8-50 mg/mL (r 5 0.9999) with a limit of detection and quantification 0.0410 and 0.1242 mg/mL, respectively. The developed method has the requisite accuracy, selectivity, sensitivity and precision to assay NTZ in presence of its degradation products either in bulk powder or in pharmaceutical formulations. The degradation products were then identified by HPLC-MS/MS analysis using an electrospray ionization source and an ion trap analyzer.

Journal of Cardiovascular Electrophysiology, 1996

Azimilide and Atrial Flutter. Introduction: The effects of a Class III a^ent, azimilide dihydroth... more Azimilide and Atrial Flutter. Introduction: The effects of a Class III a^ent, azimilide dihydrothloridc, on atrial flutter circuits were studied in a functional model of single loop reentrant arrial flutter using dogs, 3 to 5 days after production of sterile pericarditis.

Journal of Cardiovascular Electrophysiology, 2001

Azimilide and Dofetilide Atrial Flutter Ef cacy. Introduction: Azimilide dihydrochloride blocks b... more Azimilide and Dofetilide Atrial Flutter Ef cacy. Introduction: Azimilide dihydrochloride blocks both the rapid (I K r ) and slow (I K s ) components of the delayed recti ed K 1 current; dofetilide blocks only I K r . Their ef cacies were assessed on atrial utter reentrant circuits in dogs with surgically induced right atrial enlargement.

Drug Testing and Analysis, 2010

Hydrochlorothiazide (HCT) and spironolactone (SPR) are mostly co-formulated in antihypertensive f... more Hydrochlorothiazide (HCT) and spironolactone (SPR) are mostly co-formulated in antihypertensive formulations. Several methods have been developed and validated for their determination; these methods include spectrophotometric and chemometric-assisted spectrophotometric methods. The developed spectrophotometric methods were isosbestic point (ISO) and ratio subtraction (RS) methods. The absorbance values at 232.4 (λ iso1 ) and 257.6 nm (λ iso2 ) were used for determination of the total mixture concentration, while HCT could be directly determined at 317.2 nm (λ max ) and by subtraction SPR concentration could be obtained. Also SPR concentration could be calculated by RS method using the absorbance at 243.8 nm (λ max ). A wavelength selection method based on genetic algorithm (GAs) was developed and compared to the conventional partial least squares method (PLS). In this method, several parameters were adjusted and the optimum parameter settings were determined using experimental design. The developed chemometric methods were successfully applied for the determination of the HCT and SPR, as well as for determination of their impurities and degradation products. The proposed methods were successfully applied for determination of HCT and SPR in commercial tablets and they were statistically compared to each other and to the reported method. No significant difference was found, providing their accuracy and precision.

Drug Testing and Analysis, 2009

In this work two well known oral hypoglycemic drugs that are administered in combination for pati... more In this work two well known oral hypoglycemic drugs that are administered in combination for patients with type-II diabetes were simultaneously determined. Several spectrophotometric methods were developed and validated for the determination of metformin hydrochloride (MET), pioglitazone hydrochloride (PIO) and pioglitazone acid degradate (PIO Deg). Derivative, ratio derivative, isosbestic and chemometric-assisted spectrophotometric methods were developed. The first derivative (D 1 ) method was used for the determination of MET in the range of 5-30 µg.mL −1 and PIO in the range of 10-90 µg.mL −1 by measuring the peak amplitude at 247 nm and 280 nm, respectively. The concentration of PIO was calculated directly at 268 nm. The first derivative of ratio spectra (DD 1 ) method used the peak amplitudes at 238 nm and 248.6 nm for the determination of MET in the range of 5-30 µg.mL −1 .

CHEMICAL & PHARMACEUTICAL BULLETIN, 2007

Norfloxacin (Nor), (1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7 (1-piperazinyl)-3-quinoline carboxylic a... more Norfloxacin (Nor), (1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7 (1-piperazinyl)-3-quinoline carboxylic acid is a synthetic an-tibacterial drug.1,2) Methods were reported for its determina-tion as titrimetric,3) LC,4—10) LC-MS,11—13) spectrometric,14—16) spectrofluorimetric17—20) ...

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, Jan 8, 2015

Smart spectrophotometric methods have been applied and validated for the simultaneous determinati... more Smart spectrophotometric methods have been applied and validated for the simultaneous determination of a binary mixture of chloramphenicol (CPL) and prednisolone acetate (PA) without preliminary separation. Two novel methods have been developed; the first method depends upon advanced absorbance subtraction (AAS), while the other method relies on advanced amplitude modulation (AAM); in addition to the well established dual wavelength (DW), ratio difference (RD) and constant center coupled with spectrum subtraction (CC-SS) methods. Accuracy, precision and linearity ranges of these methods were determined. Moreover, selectivity was assessed by analyzing synthetic mixtures of both drugs. The proposed methods were successfully applied to the assay of drugs in their pharmaceutical formulations. No interference was observed from common additives and the validity of the methods was tested. The obtained results have been statistically compared to that of official spectrophotometric methods t...

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2015

The resolving power of spectrophotometric assisted mathematical techniques were demonstrated for ... more The resolving power of spectrophotometric assisted mathematical techniques were demonstrated for the simultaneous determination of perindopril arginin (PER) and amlodipine besylate (AML) in presence of their degradation products. The conventional univariate methods include the absorptivity factor method (AFM) and absorption correction method (ACM), which were able to determine the two drugs, simultaneously, but not in the presence of their degradation products. In both methods, amlodipine was determined directly at 360nm in the concentration range of 8-28μgmL(-1), on the other hand perindopril was determined by AFM at 222.2nm and by ACM at 208nm in the concentration range of 10-70μgmL(-1). Moreover, the applied multivariate calibration methods were able for the determination of perindopril and amlodipine in presence of their degradation products using concentration residuals augmented classical least squares (CRACLS) and partial least squares (PLS). The proposed multivariate methods were applied to 19 synthetic samples in the concentration ranges of 60-100μgmL(-1) perindopril and 20-40μgmL(-1) amlodipine. Commercially available tablet formulations were successfully analysed using the developed methods without interference from other dosage form additives except PLS model, which failed to determine both drugs in their pharmaceutical dosage form.

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, Jan 5, 2015

Smart and novel spectrophotometric and chemometric methods have been developed and validated for ... more Smart and novel spectrophotometric and chemometric methods have been developed and validated for the simultaneous determination of a binary mixture of chloramphenicol (CPL) and dexamethasone sodium phosphate (DSP) in presence of interfering substances without prior separation. The first method depends upon derivative subtraction coupled with constant multiplication. The second one is ratio difference method at optimum wavelengths which were selected after applying derivative transformation method via multiplying by a decoding spectrum in order to cancel the contribution of non labeled interfering substances. The third method relies on partial least squares with regression model updating. They are so simple that they do not require any preliminary separation steps. Accuracy, precision and linearity ranges of these methods were determined. Moreover, specificity was assessed by analyzing synthetic mixtures of both drugs. The proposed methods were successfully applied for analysis of bo...

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2015

Two methods are developed for simultaneous estimation of paracetamol, domperidone and tramadol HC... more Two methods are developed for simultaneous estimation of paracetamol, domperidone and tramadol HCl in pure and tablet dosage form by using 0.1N NaOH as a solvent. Paracetamol, domperidone and tramadol HCl show absorbance maximums at 256 nm, 289.6 nm and 218.4 nm respectively. Shimadzu UV 1700, capable of multicomponent analysis, was used for quantitation. In method I, absorbance of the sample solution was measured at 256 nm and 289.6 nm for the estimation of paracetamol, domperidone respectively as tramadol HCl does not absorb at these wavelengths. Estimation of tramadol HCl was carried out at 218.4 nm. Method II is based on a multiwavelength spectroscopic method. Validation study reveals that the methods are specific, accurate, precise, and reproducible. All three drugs obey Beer's law in the concentration ranges used for the methods. Validation studies are statistically significant as all the statistical parameters are within the acceptance range (% COV< 2.0 and S.D. < 2.0) for both accuracy and precision study. High recovery and low % COV reveals the reliability of the method for quantitative study of three drugs in tablet formulation. The methods are simple, rapid accurate, precise, reproducible, and economic and can be used for routine quantitative analysis of paracetamol, domperidone and tramadol HCl in pure and tablet dosage form.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2015

This work is concerned with development and validation of three simple, specific, accurate and pr... more This work is concerned with development and validation of three simple, specific, accurate and precise spectrophotometric methods for determination of flumethasone pivalate (FP) and clioquinol (CL) in their binary mixture and ear drops. Method A is a ratio subtraction spectrophotometric one (RSM). Method B is a ratio difference spectrophotometric one (RDSM), while method C is a mean center spectrophotometric one (MCR). The calibration curves are linear over the concentration range of 3-45 μg/mL for FP, and 2-25 μg/mL for CL. The specificity of the developed methods was assessed by analyzing different laboratory prepared mixtures of the FP and CL. The three methods were validated as per ICH guidelines; accuracy, precision and repeatability are found to be within the acceptable limits.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2015

Journal of Pharmaceutical Analysis, 2014

Determination of a novel ACE inhibitor in the presence of alkaline and oxidative degradation prod... more Determination of a novel ACE inhibitor in the presence of alkaline and oxidative degradation products using smart spectrophotometric and chemometric methods, Journal of Pharmaceutical Analysis, http: //dx.

Talanta, 2014

Imidapril hydrochloride (IMD) is a recently developed prodrug-type angiotensin-converting enzyme ... more Imidapril hydrochloride (IMD) is a recently developed prodrug-type angiotensin-converting enzyme (ACE) inhibitor. Due to its instability under both hydrolytic and oxidative conditions, development of rapid, simple and sensitive methods for its determination in the presence of its possible degradation products is essential. We proposed two simple liquid chromatographic methods associated with ultraviolet detection. The first method is an HPTLC-densitometric one in which separation of IMD from its degradation products was achieved followed by densitometric scanning at 220 nm using silica gel F 254 plates and chloroform:ethanol:acetic acid (3:0.5:0.1, v/v/v) as the developing system. The second method was based on RP-HPLC in which the separation was performed using C18 analytical column and isocratic elution system with acetonitrile: 0.15% triethylamine (pH ¼2.2) (40:60, v/v). The optimum flow rate was 1.5 mL min À 1 and the detection was at 220 nm. Validation was conducted in compliance with the ICH guidelines and the methods were successfully applied for IMD determination in its commercial tablets. The obtained results were statistically compared to those obtained by applying reported HPLC method where no significant difference was found in accordance with accuracy and precision.

Talanta, 2010

Simple, accurate, sensitive and validated UV spectrophotometric, chemometric and HPTLC-densitomet... more Simple, accurate, sensitive and validated UV spectrophotometric, chemometric and HPTLC-densitometric methods were developed for determination of oxybutynin hydrochloride (OX) in presence of its degradation product and additives in its pharmaceutical formulations. Method A is the first derivative of ratio spectra (DD(1)) which allows the determination of OX in presence of its degradate in pure form and tablets by measuring the peaks amplitude at 216 nm. Method B and C are principal component regression (PCR) and partial least-squares (PLS) for determination of OX in presence of its degradate in pure form, tablets and syrup. While, the developed high performance thin layer chromatography HPTLC-densitometric method was based on the separation of OX from its degradation product, methylparaben and propylparaben followed by densitometric measurement at 220 nm which allows the determination of OX in pure form, tablets and syrup. The separation was achieved using HPTLC silica gel F(254) plates and chloroform:methanol:ammonia solution:triethylamine (100:3:0.5:0.2, v/v/v/v) as the developing system. The accuracy, precision and linearity ranges of the developed methods were determined. The results obtained were statistically compared with each other and to that of a reported HPLC method, and there was no significant difference between the proposed methods and the reported method regarding both accuracy and precision.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014

Materials Chemistry and Physics, 2010

A series of alkyl dimethylisopropylammonium hydroxide cationic surfactants (DEDIAOH, DODIAOH and ... more A series of alkyl dimethylisopropylammonium hydroxide cationic surfactants (DEDIAOH, DODIAOH and HEDIAOH) was synthesized and characterized. The surface properties such as the critical micelle concentration (CMC), the effectiveness of surface tension reduction (˘C MC ), surface excess concentration ( max ) and surface area per molecule (A min ) have been determined by means of surface tension measurements. The degree of counter ion dissociation (ˇ) and the free energy of micellization ( G mic ) were calculated. The corrosion inhibition of the synthesized cationic surfactants on carbon steel surface in 1 M HCl solution was investigated. For this purpose, a series of techniques such as gravimetric measurement, potentiodynamic polarization and scanning electron microscope (SEM) were used. The values of activation energy for carbon steel corrosion and the thermodynamic parameters such as adsorption equilibrium constant (K ads ), free energy of adsorption ( G • ads ), adsorption heat ( H • ads ) and adsorption entropy ( S • ads ) values were evaluated. Results showed that HEDIAOH had better inhibition effect than DEDIAOH and DODIAOH of the corrosion of carbon steel in 1 M HCl solution and inhibition efficiency is higher than 96% after 24 h at 1 × 10 −2 M concentration of the inhibitor. The inhibition efficiency is discussed in terms of strong adsorption of the inhibitor molecules on the metal surface and formation of a protective film. Scanning electron microscope (SEM) showed a good surface coverage on the metal surface. The Biological activity was examined against sulfate reducing bacteria (SRB) by dilution method.

Journal of Dispersion Science and Technology, 2012

In this paper, three deferent surfactants as corrosion inhibitor were prepared in two steps; In t... more In this paper, three deferent surfactants as corrosion inhibitor were prepared in two steps; In the first step, maleic anhydride was amidated with dodecylamine to produce polyoxy ethylenyl-2-ene-4-dodecanamide butanoic acid. In the second step, the resulting product was further was further esterified with different molecular weights of polyethylene glycol (m. wt. = 200, 400 and 600) namely; MP2, MP4 and MP6. The

Journal of Chromatographic Science, 2013

A simple and sensitive stability indicating HPLC method was developed and validated for quantitat... more A simple and sensitive stability indicating HPLC method was developed and validated for quantitative determination of Nitazoxanide (NTZ), a new antiprotozoal drug, in presence of degradation products generated under forced alkaline hydrolysis. Chromatographic separation was achieved on Inertsil C8-3 column (150 3 4.6 mm i.d.) using a mobile phase composed of acetonitrile: 50 mM ammonium acetate buffer (50:50, v/v, pH 5.0 adjusted with acetic acid) at a flow rate of 1 mL/min. Quantification was achieved with UV detection at 298 nm based on relative peak area. The method was linear over the concentration range of 0.8-50 mg/mL (r 5 0.9999) with a limit of detection and quantification 0.0410 and 0.1242 mg/mL, respectively. The developed method has the requisite accuracy, selectivity, sensitivity and precision to assay NTZ in presence of its degradation products either in bulk powder or in pharmaceutical formulations. The degradation products were then identified by HPLC-MS/MS analysis using an electrospray ionization source and an ion trap analyzer.

Journal of Cardiovascular Electrophysiology, 1996

Azimilide and Atrial Flutter. Introduction: The effects of a Class III a^ent, azimilide dihydroth... more Azimilide and Atrial Flutter. Introduction: The effects of a Class III a^ent, azimilide dihydrothloridc, on atrial flutter circuits were studied in a functional model of single loop reentrant arrial flutter using dogs, 3 to 5 days after production of sterile pericarditis.

Journal of Cardiovascular Electrophysiology, 2001

Azimilide and Dofetilide Atrial Flutter Ef cacy. Introduction: Azimilide dihydrochloride blocks b... more Azimilide and Dofetilide Atrial Flutter Ef cacy. Introduction: Azimilide dihydrochloride blocks both the rapid (I K r ) and slow (I K s ) components of the delayed recti ed K 1 current; dofetilide blocks only I K r . Their ef cacies were assessed on atrial utter reentrant circuits in dogs with surgically induced right atrial enlargement.

Drug Testing and Analysis, 2010

Hydrochlorothiazide (HCT) and spironolactone (SPR) are mostly co-formulated in antihypertensive f... more Hydrochlorothiazide (HCT) and spironolactone (SPR) are mostly co-formulated in antihypertensive formulations. Several methods have been developed and validated for their determination; these methods include spectrophotometric and chemometric-assisted spectrophotometric methods. The developed spectrophotometric methods were isosbestic point (ISO) and ratio subtraction (RS) methods. The absorbance values at 232.4 (λ iso1 ) and 257.6 nm (λ iso2 ) were used for determination of the total mixture concentration, while HCT could be directly determined at 317.2 nm (λ max ) and by subtraction SPR concentration could be obtained. Also SPR concentration could be calculated by RS method using the absorbance at 243.8 nm (λ max ). A wavelength selection method based on genetic algorithm (GAs) was developed and compared to the conventional partial least squares method (PLS). In this method, several parameters were adjusted and the optimum parameter settings were determined using experimental design. The developed chemometric methods were successfully applied for the determination of the HCT and SPR, as well as for determination of their impurities and degradation products. The proposed methods were successfully applied for determination of HCT and SPR in commercial tablets and they were statistically compared to each other and to the reported method. No significant difference was found, providing their accuracy and precision.

Drug Testing and Analysis, 2009

In this work two well known oral hypoglycemic drugs that are administered in combination for pati... more In this work two well known oral hypoglycemic drugs that are administered in combination for patients with type-II diabetes were simultaneously determined. Several spectrophotometric methods were developed and validated for the determination of metformin hydrochloride (MET), pioglitazone hydrochloride (PIO) and pioglitazone acid degradate (PIO Deg). Derivative, ratio derivative, isosbestic and chemometric-assisted spectrophotometric methods were developed. The first derivative (D 1 ) method was used for the determination of MET in the range of 5-30 µg.mL −1 and PIO in the range of 10-90 µg.mL −1 by measuring the peak amplitude at 247 nm and 280 nm, respectively. The concentration of PIO was calculated directly at 268 nm. The first derivative of ratio spectra (DD 1 ) method used the peak amplitudes at 238 nm and 248.6 nm for the determination of MET in the range of 5-30 µg.mL −1 .

CHEMICAL & PHARMACEUTICAL BULLETIN, 2007

Norfloxacin (Nor), (1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7 (1-piperazinyl)-3-quinoline carboxylic a... more Norfloxacin (Nor), (1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7 (1-piperazinyl)-3-quinoline carboxylic acid is a synthetic an-tibacterial drug.1,2) Methods were reported for its determina-tion as titrimetric,3) LC,4—10) LC-MS,11—13) spectrometric,14—16) spectrofluorimetric17—20) ...

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, Jan 8, 2015

Smart spectrophotometric methods have been applied and validated for the simultaneous determinati... more Smart spectrophotometric methods have been applied and validated for the simultaneous determination of a binary mixture of chloramphenicol (CPL) and prednisolone acetate (PA) without preliminary separation. Two novel methods have been developed; the first method depends upon advanced absorbance subtraction (AAS), while the other method relies on advanced amplitude modulation (AAM); in addition to the well established dual wavelength (DW), ratio difference (RD) and constant center coupled with spectrum subtraction (CC-SS) methods. Accuracy, precision and linearity ranges of these methods were determined. Moreover, selectivity was assessed by analyzing synthetic mixtures of both drugs. The proposed methods were successfully applied to the assay of drugs in their pharmaceutical formulations. No interference was observed from common additives and the validity of the methods was tested. The obtained results have been statistically compared to that of official spectrophotometric methods t...