A. M. El Walily

Spectrophotometric and high performance liquid chromatographic determination of cetirizine dihydrochloride in pharmaceutical tablets

Derivative spectrophotometric, colorimetric and high performance liquid chromatographic methods, for the determination of the antihistaminic cetirizine dihydrochloride in tablet form were described. Spectrophotometrically, cetirizine was determined by the measurement of its first (1D) and second (2D) derivative amplitudes at 239 (peak) and 243-233 nm (peak-to-trough), respectively. The aqueous solutions obeyed Beers law in the concentration ranges of 1.2-10.0 and 0.8-10.0 micrograms ml-1 for 1D and 2D measurements, respectively. The colorimetric procedure was based on measuring the absorbency of the coloured chromogen resulted from the reaction between cetirizine sodium salt in polar solvent (DMF) and chloranil at 556 nm. The relation with concentrations was linear over 120-250 micrograms ml-1. Optimization of the reaction conditions was studied. At the same time, investigation of the complex formed was made with respect to its composition and the associated constant. A simple liquid chromatographic assay has been developed for the determination of cetirizine dihydrochloride in the presence of one of its synthesis precursor (hydroxyzine hydrochloride). A Bondapak-C18 column was used with a mobile phase consisting of acetonitrile/0.01 M ammonium dihydrogen phosphate (32:68, v/v) containing 0.1% w/v tetrabutyl ammonium hydrogen sulphate adjusted to pH 3 with phosphoric acid at a flow rate of 2 ml min-1. With salicylic acid as internal standard, quantitation was achieved with UV detection at 230 nm based on the peak height ratios. Beers law was obeyed in a concentration range of 3-35 micrograms ml-1 and the regression line equation was derived with a correlation coefficient of 0.9999. The validity of the methods was further confirmed using the standard addition method. The proposed procedures were successfully applied to the determination of cetirizine in bulk and tablet form, with high percentage of recovery, good accuracy and precision.

Utilization of carbon disulphide for the analytical determination of betahistine hydrochloride and captopril in their pharmaceutical preparations

Spectrophotometric, atomic absorption spectrometric and high performance liquid chromatographic (HPLC) procedures have been developed for the determination of betahistine hydrochloride and captopril. The three procedures are based on the reaction of the drugs with carbon disulphide in alkaline medium with the formation of the dithiocarbamate or the trithiocarbonate derivative of betahistine (BHT) and captopril (CAP), respectively, then subsequent chelation with divalent metals. The absorbance measurement of the formed chelates or of the metal moiety of chelates was used as the basis for the spectrophotometric and atomic absorption spectrometric determinations. The formed complexes have been used as pre-column derivatizing procedure for the HPLC determination of the two drugs. The different experimental conditions were optimized. The calibration graphs were linear over the applicable concentration ranges. The proposed procedures were applied successfully for the determination of the two investigated drugs in their tablets dosage form.

Simultaneous determination of tenoxicam and 2-aminopyridine using derivative spectrophotometry and high-performance liquid chromatography

Derivative spectrophotometry and high-performance liquid chromatography (HPLC) were used to determine tenoxicam and one of its decomposition products (2-aminopyridine) simultaneously and in the presence of each other. The derivative procedure was based on the linear relationship between the tenoxicam concentration and the second derivative amplitudes at 390-348 nm (peak-to-trough) measurement. The 2-aminopyridine was determined through measuring the second derivative amplitude at 241 nm (zero-crossing for tenoxicam). For the HPLC procedure, a reversed-phase C8 column with a mobile phase composed of 0.02 M sodium acetate-methanol-acetonitrile (11:8:1) with 0.005 M heptane sulfonic acid sodium salt, as an ion pair, was used to separate both compounds with 2,4-dinitrochlorobenzene, as an internal standard, in reasonable time. The flow rate was 1.5 ml min-1 with a programmable ultraviolet (UV) detection at 300 and 375 nm. Both UV derivative spectrophotometric and HPLC approaches were followed for confirming the purity of tenoxicam in bulk and tablets dosage form.

Spectrophotometric investigation of the formed chelate between timonacic and palladium(II) and its analytical applications

A simple spectrophotometric method for the determination of timonacic is presented. The procedure is based on the chelate formation with palladium(II) chloride in buffered medium. The optimum conditions for the complex formation were ascertained and the method was developed for the determination of timonacic in the concentration range of 28-48 micrograms ml-1. The emperical formula of the formed complex was determined, by applying different spectrophotometric methods, at optimum pH of 4.8 and an ionic strength of mu = 0.5. The stoichiometric ratio was found to be 2:1 (timonacic/palladium) as calculated by the mole ratio, continuous variations and Asmus methods. The continuous variations and Nash methods were applied for the determination of the conditional stability constant of the formed yellow-water soluble complex and was found to be 3.27 x 10(7). The proposed methods was found to be suitable for the determination of timonacic in bulk and in its pharmaceutical tablets.

Liquid Chromatographic Determination of Rutin and Ascorbic Acid-Binary Mixture in Pharmaceutical Preparations

Abstract A liquid chromatographic procedure for the separation and determination of rutin and ascorbic acid in oral dosage forms is described. The dosage content of tablets and soft gelatin capsules is diluted and chromatographed on a Lichrosorb (C18) column with a mobile phase of wat er∼methanol (55–45 V/V) and detection at 250 nm. Phenacetin was used as internal standard. The calibration is linear with correlation coefficient of 0.9999 for each component. Recoveries of spicked excipients averaged 99.5% and 99.2% for rutin and 100.2% and 99.8% for ascorbic acid in tablets and soft gelatin capsules, respectively. The method met USP XXII requirements for system suitability with proper resolution between two adjacent peaks. The relative standard deviation (RSD) of peak response of each component (obtained by chromatographing five replicates of standard solution) is less than 2% and tailing factor of each component is not greater than 1.5. The method can be used for composite and content uniformity assay of ...

HPLC method of analysis of cephadroxil and its application in bioavailability studies

A rapid, simple, sensitive and accurate HPLC method, for the determination of cephadroxil in urine, is presented using paracetamol as an internal standard. The urine samples were suitably diluted and an aliquot of the clear supernatant, after vortex–mixing and centrifugation, was directly injected into the column. The drug and internal standard were eluted from a 10–μm, C–8 reversed–phase column with a mobile phase consisting of phosphate buffer solution (pH 5)/acetonitrile (95:5) at a flow rate of 2 ml/min with ultraviolet detection at 280 run. The analysis of each sample required 6 min. The detection limit for cephadroxil in urine is 12 μg/ml. This method was applied to determine the bioavailability of cephadroxil after administration of an oral, single, dose of two commercially available capsule brands to eight healthy volunteers in a crossover design. Urine samples were collected over a 12–h period.

Stability Indicating First Derivative Sfectrophotometric: Assay for Nifedipine in Its Pharmaceutical Preparations on a Diode Array Spectrophotometer

Abstract A simple, rapid and accurate method for the simultaneous determination of nifedipine and its photodecom position products, without prior separation, is presented. The quantitation of nifedipine and its photodecom-posltion products were achieved by first derivative spectroscopy on a diode-array spectrophotometer. Both the nifedipine and the photodecompositlon products can be assyed in dasage forms by measurements of the amplitude of respectively, the peak at 402 nm and the zero crossing at 282 nm and 332 nm. The method is proved using synthetic mixtures of the intact drug with its photodecomposition products. The rate of the photodecomposition products. The rate of the photodecomposition of nifedipine to its nitroso-derivative, using fluorescent light in ethanol and in the base used as excipient in the soft gelatin capsules, was studied.

The analysis of a triple sulfonamide in pharmaceutical powder form by HPLC

Abstract A simple, accurate and reproducible liquid chromatographic procedure is developed for separating three sulfonamides. The procedure has been developed to separate and quantitate sulfaguanidine, sulfadiazine and succinyl sulfathiazole, in powdered form to be used as oral suspension, using sulfanilic acid as internal standard. A C18 reverse-phase column (25 cm × 4.6 mm i.d.; 10 μm particles) was used. The mobile phase was 20% methanol in 0.05 M ammonium acetate delivered at a flow rate of 1 mL/min. The UV detection was set at 270 nm with a band-width of 10 nm. The separation of the three sulfas was completed in about five minutes. The method met the USP requirments for system suitability and linearity (r values of 0.999 or better). The extraction of the sulfa drugs from the powder is performed by a very simple procedure. This procedure is useful for monitoring the production process of the pharmaceutical preparation containing the three sulfonamides.

An Isocrstic Reversed—Phase Separation and Determination of and Phenytoin in Tablets by High Performance Liquid Chromatogrphy

AbstractAn isocratic, sensitive high-per-Formance liquid chromatographic method has been developed for the determination of phenobarbitone, methylphenobarbitone and phenytoin in tablets. A reversed-phase octadecylsilane column, 10 µ, was utilized with a mobile phase consisting of 45% methanol, 55% water and 0.5 ml glacial acetic acid at a flow rate of 1.8 ml/min. The samples were dissolved in methanol containing diethylbarbituric acid as an internal standard. Quantitation was achieved with UV detection at 240 nm and by the measurment of the peak area ratio.

High Performance Liquid Chromatography Determination of Benzocaine And Phenindamine Tartrate In Cream

Abstract A rapid, simple and precise high-performance liquid chromatographic procedure is presented for the simultaneous determination of benzocaine (I) and phenindamine tartrate (II) in pharmaceutical preparation. The assay was carried out in a stainless steel column of μ-porasil (15 cm × 3.9 mm ID) at ambient temperature using 0.01 N of ammonium perchlorate in methanol at apparent pH of 6.7 as mobile phase. The elution was performed at flow rate of 2 ml/min. The method is sensitive in the range of 6–15.6 pg/ml and 12.6–28.8 pg/ml for benzocaine and phenandamine tartrate, respectively.