Spectrophotometric estimation of bicalutamide in tablets

A simple, sensitive, rapid, accurate and precise spectrophotometric method has been developed for the estimation of bicalutamide in bulk and pharmaceutical dosage forms. Bicalutamide shows maximum absorbance at 272 nm with molar absorptivity of 2.3399×10(4) l/mol/cm. Beer's law was obeyed in the concentration range of 1.5-18 μg/ml. The limit of detection and limit of quantification were found to be 0.1 and 0.4 μg/ml, respectively. Results of analysis were validated statistically and by recovery studies.     

Spectrophotometric determination of benazepril in tablets

A simple and sensitive spectrophotometric method has been developed for the determination of benazepril HCl in pharmaceutical formulations. The method is based on the reaction of the drug with potassium permanganate in the presence of sodium hydroxide to produce a bluish-green colored species measurable at 609.4 nm. The absorbance-concentration plot is linear over the range 1-8 microg ml(-1) with minimum detectability of 0.1 microg ml(-1) (2.17 x 10(-7) M). The molar absorptivity was 4.07 x 10(4) l mol(-1) cm(-1) with correlation coefficient (n = 6) of 0.9991. The different experimental parameters affecting the development and stability of the color were studied carefully and optimized. The proposed method was applied successfully to the determination of benazepril in its dosage forms, the percentage recoveries +/- SD (n = 9) were 99.79 +/- 1.40 and 100.50 +/- 1.48 for tablets containing 10 and 20 mg, respectively. The results obtained were in good agreement with those obtained using a reference spectrophotometric method. The proposed method could be applied to the determination of benazepril in presence of the co-formulated drug, hydrochlorothiazide. A proposal of the reaction pathway was presented.     

Spectrophotometric determination of diclofenac sodium in tablets

Simple spectrophotometric methods are described for the determination of diclofenac. In the first method diclofenac reduces iron(III) to iron(II) when heated in aqueous solution. The ferrous ions produced react with 2,2'-bipyridine to form a complex having a maximum absorbance at 520 nm. The reaction obeys Beer's Law for concentrations of 10-80 micrograms ml-1. This method can be applied to the determination of diclofenac in tablets. In the second method, diclofenac is treated with Methylene Blue in the presence of phosphate buffer (pH 6.8) and the complex is extracted with chloroform. The complex has a maximum absorbance at 640 nm and the graph of absorbance against concentration is linear in the range 5-40 micrograms ml-1. This method can be applied to the determination of diclofenac in tablets that also contain paracetamol.     

Spectrophotometric determination of rosuvastatin calcium in tablets

Rosuvastatin calcium is a synthetic lipid lowering agent which is used in hypercholesterolemia. It is a selective and competitive inhibitor of HMG-CoA reductase. In this study a simple, rapid and reliable spectrophotometric method was developed for the determination of rosuvastatin calcium in pharmaceutical preparations. The solutions of standard and pharmaceutical samples were prepared in methanol. 243 nm was chosen for measuring absorbances of rosuvastatin calcium. The developed method was validated with respect to linearity range, limit of detection and quantitation, accuracy, precision, specificity and ruggudness. The linearity range of the method was 1.0-60.0 microg mL(-1). The limit of detection was 0.33 microg mL(-1). The developed and validated method was applied to the determination of rosuvastatin calcium in pharmaceutical preparations.     

Spectrophotometric and HPLC determination of fleroxacin in tablets

The paper describes and compares spectrophotometric and HPLC determination of fleroxacin in commercial tablets. The optimum conditions for spectrophotometric assay were found to be at pH < 3.5 (0.1 M HCl) at a wave length of 286 nm. HPLC analysis was carried out on a Beckman ODS 5 microns column in a pH 3 phosphoric acid solution (detector wave length 254 nm).     

Spectrophotometric and HPLC determination of secnidazole in pharmaceutical tablets

Simple and accurate spectrophotometric and HPLC methods were developed for the determination of secnidazole in tablets dosage form. The first spectrophotometric method depends on the reduction of secnidazole molecule with zinc dust and hydrochloric acid followed by condensation with either p-dimethylaminobenzaldehyde or anisaldehyde to give colored chromogens having absorbance at 494 and 398 nm, respectively. The second method was based on the reaction of the drug with sodium nitroprusside in the presence or absence of hydroxylammonium hydrochloride. The formed colored chromogens were measured at 584 and 508 nm, respectively. The experimental conditions were optimized and Beer’s law was obeyed over the applicable concentration ranges. The application of HPLC procedures depended on using either a conventional or microbore reverse-phase (C₁₈) column along with mobile phases consisting of water and methanol (30:70), at pH of 3.5. Both techniques were applied successfully for the analysis of secnidazole in tablets form. The results obtained from both procedures were statistically compared using the Student’s-t and F-variance ratio tests.     

Spectrophotometric determination of paracetamol in pure form and in tablets

A spectrophotometric method is proposed for the determination of paracetamol in pure form and in tablets. The method depends on reaction of the drug with ammonium molybdate in strongly acidic medium to produce molybdenum blue. Effects of variables such as temperature, heating time, acidity and reagent concentration have been evaluated to permit selection of the most advantageous technique. Beer's law was followed for concentrations of up to 6 micrograms ml-1 of paracetamol and the detection limit (p = 0.05) was 0.10 microgram ml-1. The molar absorptivity at 670 nm was 2.6 x 10(4) l mol-1 cm-1 and the relevant Sandell's sensitivity of the reaction was 0.0059 microgram cm-2 per 0.001 absorbance unit. Statistical analysis of the results and comparison with results by the BP method of analysis are also reported.     

荷移分光光度法测定阿奇霉素分散片含量

目的:建立一种快速测定阿奇霉素分散片含量的方法.方法:利用阿奇霉素与茜素红在水-乙醇介质中发生电荷转移反应,形成电荷转移络合物,采用可见分光光度法测定.结果:电荷转移反应生成的荷移络合物在波长536 am处有最大吸收,表观摩尔吸光系数为1.23×104L·mol-1·cm-1,药物浓度在10～60 mg·L-1范围内服从比耳定律,方法平均回收率为100.7%,RSD为0.94%.结论:该方法稳定、准确、灵敏、快速,对样品的测定结果令人满意.     

Spectrophotometric quantitative determination of cilazapril and hydrochlorothiazide in tablets by chemometric methods

Four chemometric methods were applied to simultaneous determination of cilazapril and hydrochlorothiazide in tablets. Classical least-square (CLS), inverse least-square (ILS), principal component regression (PCR) and partial least-squares (PLS) methods do not need any priori graphical treatment of the overlapping spectra of two drugs in a mixture. For all chemometric calibrations a concentration set of the random mixture consisting of the two drugs in 0.1 M HCI and methanol (1:1) was prepared. The absorbance data in the UV-Vis spectra were measured for the 15 wavelength points (from 222 to 276 nm) in the spectral region 210-290 nm considering the intervals of deltalambda = 4 nm. The calibration of the investigated methods involves only absorbance and concentration data matrices. The developed calibrations were tested for the synthetic mixtures consisting of two drugs and using the Maple V software the chemometric calculations were performed. The results of the methods were compared each other as well as with HPLC method and a good agreement was found.     

Spectrophotometric determination of lisinopril in tablets using 1-fluoro-2,4-dinitrobenzene reagent

A spectrophotometric method for the determination of lisinopril (LN) in single and multicomponent tablets also containing hydrochlorothiazide (HCT), based on the derivatization reaction with 1-fluoro-2,4-dinitrobenzene (FDNB, Sanger reagent) is described. Aqueous solutions of LN (4.5-27.2 x 10(-5) M) react with FDNB (in acetonitrile) at pH 8.2 (borate buffer) in dark at 60 degrees C for 45 min. After acidification with HCl to decolourize 2,4-dinitrophenolate (the alkaline hydrolysis product of FDNB), the LN-derivative is measured at 356.5 or 405.5 nm (only at 405.5 nm if HCT is present). The calibration curves are linear (r>0.996 at both wavelengths) with a between days precision of slopes of 1.8 and 2.3% at 405.5 and 356.5 nm, respectively. The quantification limit is 3.49 x 10(-5) M (0.014 mg) at 405.5 nm and 5.69 x 10(-5) M (0.023 mg) at 356.5 nm. The accuracy and precision of the method were evaluated with the analysis of synthetic mixtures (Er%: 0.30-0.60 and 0.27-1.00 at 405.5 and 356.5 nm, respectively; RSD%: 0.48-0.92 and 0.35-0.51 at 405.5 and 356.5 nm, correspondingly; recovery%: 99.2-100.4 at 405.5 nm and 97.9-104.3 at 356.5 nm). Results obtained from the analysis of commercial preparations with the proposed method are in good agreement with those obtained with the official HPLC method (% relative difference 0.2-2.5%). The developed method can be used for rapid routine analysis for content uniformity, dissolution profile studies and assay of pharmaceutical preparations.     

Spectrophotometric determination of peptic ulcer sulfur-containing drugs in bulk form and in tablets

Two spectrophotometric procedures are suggested for the determination of three irreversible proton pump inhibitors, rabeprazole (RAB), omeprazole (OMP) and pantoprazole (PAN) in pure form and in different pharmaceutical formulations. The first method is based on the oxidation of RAB and PAN with potassium iodate in an acidic medium followed by extracting the liberated iodine with cyclohexane and measurement at λ = 520 nm. Beer's law is valid in the concentration ranges from 10-400 and 5-400 μg ml(-1) for RAB and PAN, respectively. The apparent molar absorptivities of the resulting coloured product were found to be 1.34 × 10(3) and 1.64 × 10(3) l.mol(-1). cm(-1) for RAB and PAN, respectively. The second method is based on the interaction of the basic drugs, OMP, RAB and PAN, in 1,2-dichloroethane with bromophenol blue (BPB), bromocresol green (BCG) and bromocresol purple (BCP) in the same solvent to produce stable coloured ion pairs with maximum absorbance at 385-405 nm. Regression analysis of Beer's plots showed good correlation in the concentration ranges 10-60, 10-60 and 5-40 μg ml(-1) for OMP, 10-150, 10-150 and 10-60 μg ml(-1) for RAB and 10-250, 10-150 and 10-100 μg ml(-1) for PAN with BPB, BCG and BCP reagents, respectively. The limits of detection are 0.46-7.69 μg ml(-1) and limits of quantitation range between 1.52-8.53 μg ml(-1). The optimum assay conditions were investigated and the recovery of the drugs from their dosage forms ranged from 99.33% to 100.5%. Intraday relative standard deviations (RSD) were 0.029-1.397% and the correlation coefficients ranged from 0.9992 to 1. The two methods can be applied successfully for the determination of these drugs in tablets. The results of analysis were validated statistically through recovery studies.