Nevin Erk

SIMULTANEOUS DETERMINATION OF PARACETAMOL AND METHOCARBAMOL IN TABLETS BY RATIO SPECTRA DERIVATIVE SPECTROPHOTOMETRY AND LC

The application of the ratio spectra derivative spectrophotometry and high-performance liquid chromatography (HPLC) to the simultaneous determination of paracetamol (PAR) and methocarbamol (MET) in combined pharmaceutical tablets is presented. The spectrophotometric procedure is based on the use of the first derivative of the ratio spectra obtained by dividing the absorbtion spectrum of the binary mixtures by a standard spectrum of one of the compounds. The first derivative amplitudes were measured at 243.0 and 230.3 nm for the assay of PAR and MET, respectively. Calibration graphs were established for 2-30 microg ml for PAR and 2-36 microg/ml for MET in binary mixture. The detection limits for PAR and MET were found 0.097 and 0.079 microg/ml, respectively; while the quantification limits were 0.573 microg/ml for PAR and 1.717 microg/ml for MET. For the HPLC procedure, a reversed-phase column with a mobile phase of methanol-water (60:40, v/v), was used to separate both compounds with a detection of 274.0 nm. Linearity was obtained in the concentration range of 2 300 and 1.5-375 microg/ml for PAR and MET, respectively. The detection and quantification limits were found to be 0.42 and 1.4 microg/ml for PAR and 0.36 and 1.2 microg/ml for MET, respectively. The relative standard deviations were found to be less than 0.52%, indicating reasonable repeatibility of both methods. The proposed methods were successfully applied to the determination of these drugs in commercial tablets.

Analysis of binary mixtures of losartan potassium and hydrochlorothiazide by using high performance liquid chromatography, ratio derivative spectrophotometric and compensation technique

A new simple, precise, rapid and selective reversed-phase high performance liquid chromatographic (HPLC) and two spectrophotometric methods have been described for resolving binary mixture of losartan potassium and hydrochlorothiazide in the pharmaceutical formulations. The first method, is based on HPLC on a reversed-phase column using a mobile phase 0.01 N sodium dihydrogen phosphate:methanol:acetonitrile (8:2:1 v/v/v) (pH 5.5) with detection at 265.0 nm. The second method, is depend on ratio derivative spectrophotometry, the amplitudes in the first derivative of the ratio spectra at 238.360 nm and at 230.423 nm were selected to simultaneously determine losartan potassium and hydrochlorothiazide in the mixture. The third method, based on compensation technique is presented for the derivative spectrophotometric determination of binary mixtures with overlapping spectra. By using ratios of the derivative maxima or the derivative minimum, the exact compensation of either component in the mixture can be achieved, followed by its determination. The accuracy and precision of the methods have been determined and they have been validated by analysing synthetic mixtures containing losartan potassium and hydrochlorothiazide. The methods do not require any separation step. The methods were also applied to the determination of losartan potassium and hydrochlorothiazide in pharmaceutical preparations. The analytical results were quite good in all cases.

Determination of active ingredients in the pharmaceutical formulations containing hydrochlorothiazide and its binary mixtures with benazepril hydrochloride, triamterene and cilazapril by ratio spectra derivative spectrophotometry and vierordt's method

Procedures were developed for the simultaneous determination of pharmaceuticals in binary mixtures, containing hydrochlorothiazide-benazepril hydrochloride, hydrochlorothiazide triamterene and hydrochlorothiazide cilazapril by ratio spectra derivative spectrophotometry and Vierordts method. Mean recoveries, relative standard deviations and linearity ranges in calibration graphs of the methods were compared. These procedures were successfully applied to three pharmaceutical formulations for the determination of active ingredients.

Extractive Spectrophotometric Determination of Atorvastatin in Bulk and Pharmaceutical Formulations

Abstract New spectrophotometric procedures have been established for the assay of atorvastatin either in bulk form or in pharmaceutical formulations. The procedures are based on the reaction between the examined drug and bromocresol green, alizarin red, or bromophenol blue producing an ion-pair complexes which can be measured at the optimum wavelengths. The optimization of the reaction conditions is investigated. Beers law is obeyed in the concentration ranges 5.0–53.0 µg mL−1, 7.1–55.8 µg mL−1, or 7.5–56.0 µg mL−1 with bromocresol green, alizarin red, or bromophenol blue, respectively. The composition of the ion-pairs was found 1:1 by Jobs method. The specific absorptivities, molar absorptivities, Sandell sensitivities, standard deviations, and percent recoveries are evaluated. On the other hands, atorvastatin was determined by measurement of its first derivative signals at 217.8 nm, respectively. Calibration graph was established for 4.2–69.0 µg mL−1 of atorvastatin for first derivative spectrophotometry. Application of the suggested methods to pharmaceutical formulations is presented and compared with the first derivative spectrophotometric method. No interference was observed from common pharmaceutical adjuvants.

Simultaneous determination of hydrochlorothiazide and amiloride hydrochloride by ratio spectra derivative spectrophotometry and high-performance liquid chromatography.

Rapid, precise, accurate and specific ratio spectra derivative spectrophotometry and high-performance liquid chromatographic procedures were described for the simultaneous determination of hydrochlorothiazide and amiloride hydrochloride in combined pharmaceutical dosage forms. For the first method, ratio spectra derivative spectrophotometry, the signals were measured at 285.7 nm for hydrochlorothiazide and at 302.5 nm for amiloride hydrochloride in the mixture, in the first derivative of the ratio spectra. The second method is based on high-performance liquid chromatography (HPLC) on LiChrosorb RP-C18 column (5 microm, 20 cm x 4.6 mm) using 0.025 M orthophosphoric acid (adjusted to pH 3.0 with triethylamine (TEA)), acetonitrile (84:16 v/v) as a mobile phase at a flow rate of 1.2 ml/min(-1). Detection was carried out using a UV detector at 278.0 nm. Commercial sugar-coated and laboratory-prepared mixtures containing both drugs in different proportions were assayed using the developed methods.

Quantitative analysis of chlorpheniramine maleate and phenylephrine hydrochloride in nasal drops by differential-derivative spectrophotometric, zero-crossing first derivative UV spectrophotometric and absorbance ratio methods

Three simple, rapid and accurate methods are described for the simultaneous determination of chlorpheniramine maleate and phenylephrine hydrochloride in two component mixtures. The first method comprised of measurement of difference absorptivities derivatized in first order of a nasal drops in 0.1 N NaOH relative to that of an equimolar solution in methanol at wavelengths of 271.6 and 250.2 nm, respectively. The second method, zero-crossing derivative spectrophotometry, is based on recording the first derivative curves and determining each component using the zero-crossing technique. Using first derivative spectrophotometry, the amplitudes in the first derivative spectra at 246.5 and 238.6 nm were selected to simultaneously determine chlorpheniramine maleate and phenylephrine hydrochloride in the mixture. The presence of identical zero-crossing points for pure drugs and nasal drop solutions established the non-interference of the excipients in the absorption at these wavelengths. Absorbance ratio method was also developed for a comparison method. The proposed procedures were successfully applied to the determination of chlorpheniramine maleate and phenylephrine hydrochloride in nasal drops, with a high percentage of recovery, good accuracy and precision.

Liquid Chromatographic Determination of Atorvastatin in Bulk Drug, Tablets, and Human Plasma

Abstract A simple, specific, and accurate high performance liquid chromatographic (HPLC) method for determination of atorvastatin in bulk drug, tablets, and human plasma have been developed. Liquid chromatography was performed on a RP‐Supelcosil C18 (5 µm, 150 × 4.6 mm) column and the mobile phase consisted of an acetonitrile:methanol:water (45:45:10 v/v/v), and a flow rate of 1.0 mL/min. The effluent was monitored on a UV detector at 240 nm. Each analysis required no longer than 3.0 min. Quantification was achieved by the measurement of the peak area ratio of the drug to the internal standard (ibuprofen). For quantification, a calibration curve was constructed for atorvastatin concentration ranging between 0.5–86.0 µg/mL. Furthermore, the typical excipients included in the drug formulation (starch, lactose, glucose, sugar, talc, sodium chloride, titanium dioxide, and magnesium stearate) do not interfere with the selectivity of the method. Data, with respect to precision and accuracy and limits of detection, are reported and discussed. The proposed chromatographic method was successfully applied to the quantitative determination of atorvastatin in bulk drug, tablets, and spiked human plasma.

SPECTROPHOTOMETRIC ANALYSIS OF VALSARTAN AND HYDROCHLOROTHIAZIDE

ABSTRACT Two new methods for the simultaneous determination of valsartan and hydrochlorothiazide in pharmaceutical dosage forms have been developed. The first method, based on compensation technique is presented for the derivative spectrophotometric determination of binary mixtures with overlapping spectra. By using ratios of the derivative maxima or the derivative minimum, the exact compensation of either component in the mixture can be achieved, followed by its determination. The second method, differential derivative spectrophotometry, comprised of measurement of the difference absorptivities derivatized in the first order (ΔD 1) of a tablet extract in 0.1 N NaOH relative to that of an equimolar solution in methanol at wavelengths of 227.8 and 276.5 nm, respectively. Neither sample pre-treatment nor separation were required. These methods showed good linearity, precision, and reproducibility. The results obtained were compared with the results of reversed phase HPLC. It was found that the difference was not statistically important between these methods. The proposed methods were accurate, sensitive, precise, reproducible and could be applied directly and easily to the pharmaceutical preparations.

Spectrophotometric resolution of metronidazole and miconazole nitrate in ovules using ratio spectra derivative spectrophotometry and RP-LC.

Metronidazole and miconazole nitrate in ovules was determined by ratio spectra derivative spectrophotometry and by high-performance liquid chromatography (HPLC). The first method depends on ratio spectra first derivative spectrophotometry, by utilizing the linear relationship between substances concentration and ratio spectra first derivative peak amplitude. The ratio first derivative amplitudes at 242.6 [(1)DD(242.6)], 274.2 [(1)DD(274.2))] 261.8 [(1)DD(261.8))] 273.5 [(1)DD(273.5))]and 281.5 [(1)DD(281.5)] nm were selected for the assay of metronidazole and miconazole nitrate, respectively. The second method is based on high-performance liquid chromatography on a reversed-phase column using a mobile phase of methanol-water-phosphoric acid (30:70:0.20 v/v) (pH 2.8) with programmable detection at 220.0 nm. The minimum concentration detectable by HPLC was 0.9 microg ml(-1) for metronidazole and 0.3 microg ml(-1) for miconazole nitrate and by ratio derivative spectrophotometry 4.0 microg ml(-1) for metronidazole and 0.5 microg ml(-1) for miconazole nitrate. The proposed procedures were successfully applied to the simultaneous determination of metronidazole and miconazole nitrate in ovules with a high percentage of recovery, good accuracy and precision.

Comparison of spectrophotometric and an LC method for the determination perindopril and indapamide in pharmaceutical formulations

A new sensitive, simple, rapid and precise reversed-phase high performance liquid chromatographic (HPLC) and two spectrophotometric methods have been developed for resolving binary mixture of perindopril and indapamide in the pharmaceutical dosage forms. The first method is based on HPLC on a reversed-phase column using a mobile phase of phosphate buffer pH 2.4 and acetonitrile (7:3 v/v) was used. Linearity range for perindopril and indapamide was 5.0-70.0 and 8.0-35.0 microg ml(-1). In the second method, the first derivative spectrophotometry with a zero-crossing technique of measurement is used for the simultaneous quantitative determination of perindopril and indapamide in binary mixtures without previous separation step. Linear calibration graphs of first derivative values at 225.7 and 255.4 nm for perindopril and indapamide, respectively. The third method is based on ratio derivative spectrophotometry, the amplitudes in the first derivative of the ratio spectra at 226.5 and at 255.3 nm were selected to determine perindopril and indapamide in the binary mixture. All the proposed methods showed good linearity, precision and reproducibility. The proposed methods were successfully applied to the pharmaceutical dosage forms containing the above-mentioned drug combination without any interference by the excipients.