Marwan M Shabana

Application of LC and HPTLC-densitometry for the simultaneous determination of benazepril hydrochloride and hydrochlorothiazide

Two methods are described for the simultaneous determination of benazepril HCl and hydrochlorothiazide in binary mixture. The first method was based on HPTLC separation of the two drugs followed by densitometric measurements of their spots at 238 and 275 nm for benazepril HCl and hydrochlorothiazide, respectively. The separation was carried out on Merck HPTLC aluminum sheets of silica gel 60 F(254,) using ethyl acetate-methanol-chloroform (10:3:2 v/v) as mobile phase. Second order polynomial equation was used for the regression line in the range 2-20 and 2.5-25 microg/spot for benazepril HCl and hydrochlorothiazide, respectively. The second method was based on HPLC separation of the two drugs on reversed phase, ODS column at ambient temperature using a mobile phase consisting of acetonitrile and water (35:65 v/v) and adjusting to pH 3.3 with acetic acid. Quantitation was achieved with UV detection at 240 nm based on peak area with linear calibration curves at concentration ranges 10-60 and 12.5-75 microg ml(-1) for benazepril HCl and hydrochlorothiazide, respectively. The two proposed methods were successfully applied to the determination of both drugs in laboratory prepared mixtures and in commercial tablets. No chromatographic interference from the tablets excipients was found.

Spectrophotometric and HPTLC-densitometric determination of lisinopril and hydrochlorothiazide in binary mixtures.

Different spectrophotometric and HPTLC-densitometric methods are presented for the simultaneous determination of lisinopril and hydrochlorothiazide in pharmaceutical tablets. The spectrophotometric methods include third derivative (3D) ultraviolet spectrophotometry with zero crossing measurement at 217.4 and 233.4 nm, second derivative of the ratio spectra with measurement at 214.3 and 228.0 nm; both classical least squares and principal component regression were applied to the UV absorption and first derivative spectra of the mixture. The HPTLC method was based on separation of both drugs followed by densitometric measurements of their spots at 210 and 275 nm for lisinopril and hydrochlorothiazide, respectively. The separation was carried out on Merck HPTLC aluminum plates of silica gel 60 F254, using chloroform-ethylacetate-acetic acid (10:3:2 by vol.) as mobile phase. The linear and second order polynomial were used for the regression equation of lisinopril and hydrochlorothiazide, respectively.

Spectrophotometric determination of trifluoperazine HCl and isopropamide iodide in binary mixture using second derivative and second derivative of the ratio spectra methods

Two methods are presented for the simultaneous determination of trifluoperazine hydrochloride and isopropamide iodide in binary mixture. The first method depends on second derivative ((2)D) ultraviolet spectrophotometry, with zero crossing and peak to base measurement. The second derivative amplitudes at 270.4 and 230.2 nm were selected for the assay of trifluoperazine hydrochloride and isopropamide iodide, respectively. The second method depends on second derivative of the ratio spectra by division of the absorption spectrum of the binary mixture by a normalized spectrum of one of the components and then calculating the second derivative of the ratio spectrum. The second derivative of the ratio amplitudes at 257 and 228 nm were selected for the determination of trifluoperazine hydrochloride and isopropamide iodide, respectively. The two proposed methods were successfully applied to the determination of the two drugs in laboratory prepared mixtures and in commercial tablets.

Spectrophotometric determination of benazepril hydrochloride and hydrochlorothiazide in binary mixture using second derivative, second derivative of the ratio spectra and chemometric methods

Different spectrophotometric methods are presented for the simultaneous determination of benazepril hydrochloride and hydrochlorothiazide in pharmaceutical tablets. The first method depends on second derivative (2D) ultraviolet spectrophotometry, with zero crossing and peak to base measurement. The second derivative amplitudes at 214.8 and 227.4 nm were selected for the assay of benazepril hydrochloride and hydrochlorothiazide, respectively. The second method depends on second derivative of the ratio spectra by measurement of the amplitudes at 241.2 and 273.2 nm for benazepril hydrochloride and hydrochlorothiazide, respectively. Chemometric methods, classical least squares and principal component regression, were applied to analyze the mixture. Both the chemometric methods were applied to the zero and first order spectra of the mixture. The proposed methods were successfully applied for the determination of the two drugs in laboratory prepared mixtures and in commercial tablets.

Spectrophotometric, septrofluorimetric and LC determination of lisinopril.

Three methods are described for the determination of lisinopril in the pharmaceutical tablets. The spectrophotometric method depends on the reaction of the lisinopril with sodium hypochlorite and phenyl hydrazine to form a condensation product measured at 362 nm. The spectrophotometric method was extended to develop a stability indicating method. The spectrofluorimetric method depends on reaction of the lisinopril with o-phthalaldehyde in the presence of 2-mercaptoethanol in borate buffer pH 9.5. The fluorescence of the reaction product was measured upon excitation at a maximum of 340 nm with emission wavelength at 455 nm. The HPLC method depends on using Hypersil silica column with a mobile phase consisting of methanol-water-triethylamine (50:50:0.1 v/v) and the pH was adjusted to 2.6 with 0.1 N perchloric acid. Quantitation was achieved with UV detection at 210 nm based on peak area.

First derivative spectrophotometric, TLC-densitometric, and HPLC determination of acebutolol HCL in presence of its acid-induced degradation product.

Three methods are presented for the determination of acebutolol HCl in presence of its acid-induced degradation product. The first method was based on measurement of the first derivative amplitude of acebutolol HCl at 266.6 nm. The second method was based on separation of acebutolol HCl from its acid-induced degradation product followed by densitometric measurement of the spots at 230 nm. The separation was carried out on silica gel 60 F254, using ethanol-glacial acetic acid (4:1, v/v) as mobile phase. Second order polynomial equation was used for the regression line. The third method was based on high performance liquid chromatographic (HPLC) separation of acebutolol HCl from its acid-induced degradation product on a reversed phase, ODS column using a mobile phase of methanol-water (55:45, v/v) with UV detection at 240 nm. The first derivative spectrophotometric method was utilized to investigate the kinetics of the acid degradation process at different temperatures.

Derivative spectrophotometric, thin layer chromatographic-densitometric and high performance liquid chromatographic determination of trifluoperazine hydrochloride in presence of its hydrogen peroxide induced-degradation product

Three methods are presented for the determination of trifluoperazine HCl in presence of its hydrogen peroxide induced degradation product. The first method was based on measurement of first (1D) and second (2D) derivative amplitudes of trifluoperazine HCl in 0.1 N hydrochloric acid at the zero crossing point of its sulfoxide derivative, main degradation product, (at 268.4 and 262.5 nm for 1D and 2D, respectively). The second method was based on the separation of trifluoperazine HCl from its sulfoxide derivative followed by densitometric measurement of the intact drug spot at 255 nm. The separation was carried out on Merck aluminum sheet of silica gel 60 F(254), using chloroform-methanol (7:3 v/v) as mobile phase. The third method was based on high performance liquid chromatographic separation of trifluoperazine HCl from its sulfoxide derivative on reversed phase, ODS column, using a mobile phase of acetonitrile-phosphate buffer pH 4.2 (60:40 v/v) at ambient temperature. Quantitation was achieved with UV detection at 255 nm based on peak area. The first derivative spectrophotometric method was utilized to investigate the kinetics of the hydrogen peroxide degradation process at different temperatures. The apparent pseudo first-order rate constant, half life and activation energy were calculated.

Spectrophotometric, spectrofluorimetric and LC determination of trazodone hydrochloride.

Three methods are described for the determination of trazodone hydrochloride in pharmaceutical tablets. The spectrophotometric method was based on the formation of yellow ion pair complex between the basic nitrogen of the drug and bromophenol blue at pH 3.4. The formed complex was extracted with chloroform and measured at 414 nm. The spectrofluorimetric method was based on measurement of the native fluorescence of the drug in 50% acetic acid upon excitation at a maximum of 320 nm and the emission wavelength is 435 nm. The third method was based on the high performance liquid chromatographic determination of trazodone hydrochloride using a reversed phase, ODS column, with a mobile phase of acetonitrile--phosphate buffer at pH 4.5 (60:40, v/v). Quantization was achieved with UV detection at 250 nm based on peak area. The three methods were simple, accurate and suitable for quality control application.

Phenylalkylamine alkaloids from Stapelia hirsuta L.

Four alkaloids of the phenethylamine derivatives have been isolated from the n-butanol fraction of the aerial parts of Stapelia hirsuta L. The structures of the isolated alkaloids were determined as N-acetyl hordenine (a new natural compound), hordenine, candicine and hordenine-1-O-β-D-glucoside, in addition to luteolin-7-O-β-D-glucopyranoside.