Direct spectrophotometric determination of diacerhein in capsules

A simple, rapid and precise ultraviolet spectrophotometric method using 0.1 N sodium hydroxide has been developed and validated for the assay of diacerhein. The drug can be estimated at 277 nm (ultraviolet region, UV) as well as at 502 nm (visible region, VIS). The absorbances were linearly correlated with concentration in the 6.0-24 microg mL(-1) range (r = 0.9999) and 10-34 microg mL(-1) range (r = 0.9998), respectively at 277 and at 502 nm. The relative standard deviation values for intra (n = 6) and inter-day (n = 3) precision were <2%. Recoveries ranged between 99.0 and 101.7%. The method has been successfully applied to the drug assay in capsules. It was also found that the excipients in the commercial capsules did not interfere with the method. Statistical analysis showed no significant difference between the results obtained at two wavelengths (277 nm or 502 nm).     

HPLC测定盐酸氟西汀胶囊的含量

目的建立测定盐酸氟西汀胶囊含量的方法.方法采用高效液相色谱法,以辛烷基硅烷键合硅胶为固定相,1.0%三乙胺(用磷酸调pH6.0)-四氢呋喃-甲醇(40:40:20)为流动相,检测波长227 nm,测定盐酸氟西汀的含量.结果盐酸氟西汀在70～130μg/ml浓度范围内有良好的线性关系(r=0.9997),回收率为98.85%(RSD＝0.64%).结论本法测定盐酸氟西汀胶囊的含量,结果准确,可行.     

HPLC测定盐酸氟西汀胶囊的含量

目的建立测定盐酸氟西汀胶囊含量的方法。方法采用高效液相色谱法,以辛烷基硅烷键合硅胶为固定相,1.0%三乙胺(用磷酸调pH6.0)-四氢呋喃-甲醇(40∶40∶20)为流动相,检测波长227nm,测定盐酸氟西汀的含量。结果盐酸氟西汀在70～130μg/ml浓度范围内有良好的线性关系(r=0.9997),回收率为98.85%(RSD=0.64%)。结论本法测定盐酸氟西汀胶囊的含量,结果准确,可行。     

褪色分光光度法测定七叶皂苷钠

目的:建立褪色分光光度法测定七叶皂苷钠。方法:在 pH 3.5～4.2的 Britton—Robinson 缓冲溶液中,七叶皂苷钠与夜蓝反应,形成离子缔合物时能使染料发生明显的褪色作用。产生最大褪色波长为614 nm,并且吸收度降低与七叶皂苷钠浓度成正比。结果:七叶皂苷钠浓度在0.25～20.0μg·mL~(-1)范围内符合比耳定律,摩尔吸光系数为1.4×10~4L·mol~(-1)·cm~(-1),方法具有较高的灵敏度,其检出限为75 ng·mL~(-1),研究了共存物质的影响,表明方法选择性好。结论:此法简便、准确、灵敏,可用于片剂和尿样中七叶皂苷钠的测定。     

Visible spectrophotometric method for the determination of aripiprazole in tablets

A simple, accurate and economic spectrophotometric method for the determination of aripiprazole in tablet formulation is proposed. In the present method acidic solution of the aripiprazole formed colored ion-association complexes with bromocresol green, soluble in chloroform. Yellowish orange chromogen showed λ(max) at 414 nm and obeyed Beer's law in the concentration range of 10-60 μg/ml. Statistical analysis and recovery studies validated the method. The proposed method is rapid, precise and accurate and can be applied for the routine estimation of aripiprazole in the laboratory.     

A new spectrophotometric method for the determination of penicillins

A rapid and convenient method is described for the determination of nine commonly used penicillins. This is based on the spectrophotometric measurement at 325–345 nm of penicillenic acid mercuric mercaptides of the penicillins, formed in quantitative yield on heating at 60° or on standing at 20° in a 1·2 m imidazole and 10^?3 m mercuric chloride solution at pH 6·8. The method, which permits detection of concentrations of penicillins down to 0·5 μg/ml, is reproducible. Since the intact penicillin molecule is required for the penicillenic acid formation, the method is highly specific and useful as a means of assessing stability.     

A new spectrophotometric method for the determination of methyldopa

A new, simple and low cost spectrophotometric method for the determination of methyldopa in pharmaceutical preparations was developed. The method was based on the coupling of methyldopa with 2,6-dichloroquinone-4-chlorimide (DCQ). The absorbance maximum (λ_max) of the resulted colored product was at 400 nm. Different buffers were used to determine the optimal pH for the reaction. About 1% w/v acetate buffer with pH 8.0 gave the optimal pH required for the reaction. Of the different solvents tried, water and ethanol were found to be the most suitable solvents. Beer’s law was obeyed in concentration range of 4–20 μg/ml methyldopa. The correlation coefficient was found to be (r = 0.9975). The limit of detection and limit of quantification were 1.1 μg/ml and 3.21 μg/ml, respectively. The reaction ratio between methyldopa and DCQ was studied and found to be 1:3. The work included the study of the possible interference of hydrochlorothiazide found in combination with methyldopa tablets. The method was validated and results obtained for the assay of two different brands of methyldopa tablets were compared with the BP method (colorimetric). The repeatability and reproducibility of the developed method were evaluated and the obtained results quoted. The derivative formed as a result of the reaction of methyldopa with DCQ was isolated and its possible mechanistic pathway was suggested.     

New spectrophotometric method for the determination of flutamide in pharmaceutical preparations

A sensitive and simple spectrophotometric method for the determinations of reduction product of flutamide (FLA) is described. The method is based on the interaction of diazotized flutamide reduction product with N-(1-naphthyl) ethylenediamine dihydrochloride (NEDA) in neutral or resorcinol (RSL) in alkaline medium. Absorbance of the resulting chromophores is measured at 525 or 480 nm, respectively, and is stable for at least 7 days. The two coupling reagents are applied successfully for the determination of FLA in tablets. The common excipients used as additives in pharmaceutical preparations do not interfere with the determination. Results from the analysis of pure FLA and its commercial tablets by the proposed methods agree well with the reported method.     

A rapid spectrophotometric method for the determination of mefloquine hydrochloride

A simple ultraviolet spectrophotometric method for the estimation of mefloquine hydrochloride in methanol (ME₂) has been developed and has been compared with the reported ultraviolet spectrophotometric method in 0.1 N hydrochloric acid (ME₁). Analytical parameters such as stability, selectivity, accuracy and precision have been established for both the methods and evaluated statistically to assess the application of the individual methods. Both the methods were compared with the existing pharmacopoeial method for estimation of the drug. Both the methods were found to have the advantages for simplicity, stability, sensitivity, reproducibility and accuracy for using as an alternate to the existing non-spectrophotometric methods for the routine analysis of the drug in pharmaceutical formulations and also in pharmaceutical investigations involving mefloquine hydrochloride.     

微波消解-原子吸收分光光度法测定明胶空心胶囊中的铬试验条件探讨

目的:建立并验证用微波消解-原子吸收分光光度法测定明胶空心胶囊中铬含量的方法。方法:采用微波消解系统消解样品,以石墨炉原子吸收分光光度法测定空心胶囊中铬元素的含量。结果:线性范围为0～60 ng.mL-1,回归方程为Y=0.01730X+0.0377,r=0.9995。样品加标平均回收率分别为102.5%,87.5%,82.9%,满足要求。结论:本法结果准确、操作简便、分析速度较快,适用于明胶空心胶囊中铬的测定     

A new second-derivative spectrophotometric method for the determination of permethrin in shampoo

Permethrin, a highly effective insecticide agent, has been widely used for the pest control in agriculture and the treatment of lice in human. A fast and reliable method for the determination of permethrin was highly desirable to support formulation screening and quality control. A second-derivative UV spectroscopic method was developed for the determination of permethrin in the shampoo dosage form after extraction. The second-derivative spectrum recorded between 250 and 310 nm, and a zero-crossing technique for second-derivative measurement at 279 nm was selected. It is found that the selectivity and sensitivity of the method to be in desirable range. In comparison with the direct UV method, second-derivative UV spectroscopy eliminates the interference from UV absorbing excipients. This method is also fast and economical in comparison with the more time-consuming GC method regularly used for formulation screening and quality control and can be used routinely by any laboratory possessing a spectrophotometer with a derivative accessory. The linear concentration ranges were 0.25-1.5 ppm (D2=0.00042Conc.+0.0018, r=0.9972, n=10). Between day of CV%相似文献   

A sensitive spectrophotometric method for the determination of sulfonamides in pharmaceutical preparations

A new, simple and sensitive spectrophotometric method for the determination of some sulfonamide drugs has been developed. The method is based on the diazotization of sulfacetamide, sulfadiazine, sulfaguanidine, sulfamerazine, sulfamethazine, sulfamethoxazole, and their coupling with 8-hydroxyquinoline in alkaline media to yield red coloured products with absorption maxima at 500 nm. Beer's law is obeyed from 0.1-7.0 microg mL-1. The limits of quantification and limits of detection were 0.11-0.18 and 0.03-0.05 microg mL-1, respectively. Intraday precision (RSD 0.1-0.5%) and accuracy (recovery 97.3--100.8%) of the developed method were evaluated. No interference was observed from common adjuvants. The method has been successfully applied to the assay of sulpha drug in pharmaceutical formulations.     

Kinetic spectrophotometric method for the determination of norfloxacin in pharmaceutical formulations.

A simple and sensitive kinetic spectrophotometric method is described, based on the oxidation of norfloxacin with alkaline potassium permanganate. The reaction is followed spectrophotometrically by measuring the rate of change of absorbance at 603 nm. The initial rate and fixed time (at 3 min) methods are utilized for constructing the calibration graphs to determine the concentration of the drug. The calibration graphs are linear in the concentration ranges 2.0-20 microg ml(-1) and 1.0-20 microg ml(-1) using the initial rate and fixed time methods, respectively. The results are validated statistically and through recovery studies. The method has been successfully applied to the determination of norfloxacin in commercial dosage forms. Statistical comparison of the results with the reference method shows excellent agreement and indicates no significant difference in accuracy and precision.     

A simple spectrophotometric method for the determination of beta-blockers in dosage forms

A simple, extraction-free spectrophotometric method is proposed for the analysis of some beta-blockers, namely atenolol, timolol and nadolol. The method is based on the interaction of the drugs in chloroform with 0.1% chloroformic solutions of acidic sulphophthalein dyes to form stable, yellow-coloured, ion-pair complexes peaking at 415 nm. The dyes used were bromophenol blue (BPB), bromothymol blue (BTB) and bromocresol purple (BCP). Under the optimum conditions, the three drugs could be assayed in the concentration range 1-10 microg ml(-1) with correlation coefficient (n = 5) more than 0.999 in all cases. The stoichiometry of the reaction was found to be 1:1 in all cases and the conditional stability constant (K(F)) of the complexes have been calculated. The free energy changes (DeltaG) were determined for all complexes formed. The interference likely to be introduced from co-formulated drugs was studied and their tolerance limits were determined. The proposed method was then applied to dosage-forms the percentage recoveries ranges from 99.12-100.95, and the results obtained were compared favorably with those given with the official methods.