Spectrophotometric Determination of Piroxicam via Chelation with Fe(III) in Commercial Dosage Forms

The objective of this work is to develop and validate spectrophotometric method for the determination of piroxicam in commercial dosage forms. The method is based on the chelation of the drug with Fe(III) to form pink coloured metal chelate at room temperature which absorbs maximally at 504 nm. Beer's law is obeyed over the concentration range of 8–160 μg mL^?1 (A = 1.07 × 10^?3 + 7.75 × 10^?3 C). Under the optimized experimental conditions, proposed method is validated as per the International Conference on Harmonisation guidelines. The limits of detection and quantitation for the proposed method are 0.775 and 2.348 μg mL^?1, respectively. The proposed method has been successfully applied to the determination of piroxicam in commercial dosage forms. The results are compared with the reference El‐Ries et al. spectrophotometric method.     

Kinetic Spectrophotometric Determination of Ritodrine Hydrochloride in Dosage Forms

A simple and sensitive kinetic method was developed for the determination of ritodrine hydrochloride in pharmaceutical preparations. The method is based upon a kinetic investigation of the oxidation reaction of the drug with alkaline potassium permenganate at room temperature for a fixed 12.5 min; the absorbance of the colored permenganate ion was measured at 609 nm. The absorbance concentration plots were rectilinear over the range of 1.6–11.2 μg mL^?1 (r = 0.9992) with a minimum detectability of 0.096 μgmL^?1 (2.88 × 10^?7 M). The different experimental parameters affecting the development and stability of color were carefully studied and optimized. The determination of ritodrine hydrochloride by the fixed concentration and rate constant methods is also feasible with the calibration equations obtained, but the fixed time method has been found to be more applicable. The proposed method was applied successfully to the determination of ritodrine hydrochloride in tablets and ampoules with average recoveries of 100.37 ± 0.93% and 100.42 ± 0.87%, respectively. The results obtained were in good agreement with those obtained using a reference method for comparison. A proposal of the reaction pathway is also presented.     

多元校正滴定法测定酒石酸美托洛尔

以氢离子选择性电极为工作电极,盐酸或氢氧化钠为滴定剂,用多元校正滴定法对酒石酸美托洛尔片的含量进行了测定。探讨了盐酸或氢氧化钠测定酒石酸美托洛尔的可行性,比较了过滤和不过滤两种方法配制试液的测定结果。本法测定结果与中国药典(1995)中非水滴定法的对照偏差在1%之内;采用过滤和不过滤两种方法配制的试液测定结果之间的偏差在0.2%之内。     

Determination of Metoprolol Tartrate as Cu(II)-Dithiocarbamate Complex

Abstract

An HPLC method has been developed for the determination of the beta adrenergic blocking drug metoprolol tartrate. The method is based on the formation of a Cu (II) - dithiocarbamate complex by precolumn derivatization of secondary amino group of metoprolol with CS₂ and CuCl₂ in the presence of ammonia. The complex is extracted into chloroform and injected into the chromatograph. Chromatographic separation was performed by a RP (μ Bondapak C₁₈) column with methanol - pH 5.8 phosphate buffer (80 : 20) as the isocratic mobile phase. A variable wavelength absorbance detector (λ = 275 nm) was used. A linear relationship was obtained between peak areas and metoprolol tartrate concentrations over the range of 35 - 180 nmol ml^?1. The method was applied to the analysis of metoprolol tartrate tablets and the results were statistically compared with those obtained by official method using t - and F - tests.     

Spectrophotometric Determination of Amoxycillin in Dosage Forms

Abstract

Two spectrophotometric methods are proposed for the determination of amorycillin and its doeage fonne. Both procedures depend on the phenolic nature of the compound. The first method is based on condeneation with 4-aminoautipyrine in the presence of an alkaline oxidising agent. A red coloured antipyrine dye peaking at 500 nm. is produced. The second method involves the use of folin's reagent, a blue colour with λ max at 670 nm is obtained. The proposed methods could be applied successfully for the determination of dosage forms containing amoxycillin, and the results obtained were compared favourably with those obtained with the official methods.     

Spectrophotometric Determination of Lisinopril in Pure and Pharmaceutical Formulations

An accurate, simple, fast, and cheap spectrophotometric method has been developed for the determination of lisinopril in pharmaceutical pure and dosage forms. The method is based on the reaction of ninhydrin with primary amine present in the lisinopril in the presence of DMF. This reaction produces a greenish blue colored product which absorbs maximally at 600 nm. Beer's law was obeyed in the range of 10–150 μg/mL with molar absorptivity of 4.083 × 10³ L mole^?1 cm^?1. The effects of variables such as temperature, heating time, concentration of color producing reagent, and stability of color were investigated to optimize the procedure. The results are validated statistically. The proposed method was applied to commercially available tablets, and the results were statistically compared with the official potentiometric method.     

Spectrophotometric Determination of Cefadroxil and Metyrosine in Dosage Forms

Abstract

A simple and sensitive spectrophotometric method is described for the determination of cefadroxil and metyrosine in pure form and in pharmaceutical formulations. The method is based on reacting these drugs with 4-aminoantipyrine (AAP) in the presence of an alkaline oxidising agent. The coloured products were measured spectrophotometrically at 500 nm and 470 nm for cefadroxil and metyrosine, respectively. Beer's law was obeyed over the concentration range 1-28 and 2-44 μg ml^-1 for cefadroxil monohydrate and metyrosine, respectively. The molar ratio in both cases was established and a proposal for the reaction pathway was suggested. The percentage recoveries obtained were in accordance with those given by the reference methods.     

Quantitation of Diltiazem Hydrochloride in Commercial Dosage Forms by Visible Spectrophotometry

A selective and sensitive visible spectrophotometric method has been described for the quantitation of diltiazem hydrochloride in commercial dosage forms. The method is based on the reaction of the tertiary amino group of the drug with sodium hypochlorite to form the chloro drug derivative, followed by the destruction of the excess hypochlorite by sodium nitrite and the subsequent development of blue color takes place by the reaction of chloro derivative of drug with starch and potassium iodide in sodium bicarbonate medium. The maximum absorbance of the resulting blue solution is read at 540 nm. Under the optimized experimental conditions, Beer's law is obeyed in the concentration range of 2.5–25.0 μg mL^?1 with a linear regression equation of A = 9.85 × 10^?4 + 4.90 × 10^?2 C and coefficient of correlation, r = 0.9999. The molar absorptivity is found to be 2.26 × 10⁴L mol^?1 cm^?1. The limits of detection and quantitation of the proposed method are 0.12 and 0.37 μg mL^?1, respectively. The proposed method has been successfully applied for the quantitation of diltiazem hydrochloride in commercial dosage forms. The results of the proposed method compared with those of Abdellatef's spectrophotometric method presented good mean recovery with acceptable true bias of all pharmaceutical samples within ± 2.0%.     

Spectrophotometric Determination of Thioctic Acid in its Dosage Forms through Complex Formation with Pd(II)

A simple and sensitive spectrophotometric method has been developed for the determination of thioctic acid in pharmaceutical preparations. The proposed method is based upon the formation of a complex with palladium(II) in acetate buffer of pH 4.8 with an absorption maximum at 318 nm. The absorbance obeyed Beer's law over the range of 2–20 μg mL^?1 with a minimum detection limit of 0.15 μg mL^?1 and molar absorptivity (ζ) of 7 × 10³ L mol^?1.cm^?1. The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. The proposed method was successfully applied to the analysis of commercial tablets and ampoules. The results obtained were in good agreement with those obtained using a reference spectrophotometric method. A proposal of the reaction pathway is presented.     

Spectrophotometric Determination of Ondansetron Hydrochloride in Pharmaceutical Bulk and Dosage Forms

A rapid, simple and accurate spectrophotometric method is developed for the determination of ondansetron hydrochloride in pure and tablet formulations. The method depends on the charge‐transfer complexation between ondansetron base as n‐electron donor with chloranil as π‐acceptor to give a colored complex, which absorbs maximally at 470 nm. Beer's law is obeyed in the concentration ranges 70–980 μg mL^?1 with molar absorptivity of 4.47 × 10² L mole^?1 cm^?1. The proposed method is precise, accurate and specific for the quantitative determination of drug in bulk and tablet formulations.     

Determination of Labetalol Hydrochloride in Drug Formulations by Spectrophotometry

A validated, selective and sensitive spectrophotometric method has been developed for the determination of labetalol hydrochloride in commercial dosage forms. The method is based on the coupling reaction of positive diazonium ion of 4‐aminobenzenesulfonic acid with phenolate ion of labetalol to form a colored azo compound which absorbs maximally at 395 nm. Under the optimized experimental conditions, the color is stable up to 2 h and Beer's law is obeyed in the concentration range of 0.8–17.6 μg mL^?1 with a linear regression equation of A = 4.84 × 10^?4 + 7.864 × 10^?2 C and coefficient of correlation, r = 0.9999. The molar absorptivity and Sandell's sensitivity are found to be 2.874 × 10⁴ L mol^?1 cm^?1 and 0.013 μg cm^?2 per 0.001‐absorbance unit, respectively. The limits of detection and quantitation of the proposed method are 0.08 and 0.23 μg mL^?1, respectively. The intra‐day and inter‐day precision variation and accuracy of the proposed method is acceptable with low values of standard analytical error. The recovery results obtained by the proposed method in drug formulations are acceptable with mean percent recovery ± RSD of 99.97 ± 0.52 ‐ 100.03 ± 0.63%. The results of the proposed method compared with those of Bilal's spectrophotometric method indicated excellent agreement with acceptable true bias of all samples within ± 2.0%.     

Vanadophosphoric Acid as a Modified Reagent for the Spectrophotometric Determination of Certain Cephalosporins and their Dosage Forms

Summary.  Vanadophosphoric acid in acidic medium is proposed as a modified reagent for the spectrophotometric determination of cephalexin, cephaprine sodium, cefazolin sodium, and cefotaxime in pure samples and in pharmaceutical preparations. The method is based on acid hydrolysis of cephalosporins and subsequent oxidation with vanadophosphoric acid. The resulting solution exhibits maximum absorption at about 516 nm. The effects of reaction conditions were investigated. Lambert-Beer’s law was obeyed over a concentration range of about 0.4–45 μg · cm⁻³. For more accurate results, Ringbom optimum concentration ranges were obtained, and the molar absorptivities and Sandell sensitivities were derived. The proposed method was applied to the determination of the drugs in pharmaceutical formulations; the results demonstrated that the proposed method is as accurate, pecise, and reproducible as the official methods. Received August 13, 1999. Accepted (revised) December 7, 1999     

Spectrophotometric Determination of Certain Phenothiazines and Their Dosage Forms Using Bromophenol Blue

Abstract

A simple and rapid spectrophotometric method for the determination of seven phenothiazine derivatives has been performed either in pure form or in their dosage forms. The method is based upon the interaction of the drug in dry chloroform with bromophenol blue in the same solvent to produce a stable yellow ion-pair complex which absorbs at 410 nm, with high apparent molar absorptivity. Beer's Law is obeyed in the concentration range 1?10 ugml^?1 for the studied compounds. The mean recoveries range from 99.80±0.74 to 100.50±1.33. The proposed method is applied for the analysis of the studied compounds in their commercial preparations. Results are in good agreement with those obtained by official methods.     

Spectrophotometric Determination of Dextromethorphan Hydrobromide and Ketamine Hydrochloride in Pure and Dosage Forms

Three simple, sensitive and accurate spectrophotometric methods have been developed for the determination of dextromethorphan hydrobromide (DEX) and ketamine hydrochloride (KET) in dosage forms. These methods are based on the formation of ion‐pair complexes with bromocresol green (BCG), bromocresol purple (BCP), and bromophenol blue (BPB) in acidic medium. The coloured ion‐pair products are measured at 419, 409 and 417 nm for DEX and at 417, 408 and 416 nm for KET using BCG, BCP and BPB, respectively. Beer's law was obeyed in the range of 2.0–22 μg mL^?1 for DEX and 2.0–16 μg mL^?1 for KET. The composition of the ion‐pair was established by continuous variation and molar ratio methods. The proposed methods were applied successfully for the determination of DEX and KET in dosage forms applying the standard addition technique and compared statistically with the official methods. The molar absorptivity, Sandell sensitivity, detection and quantification limits were also calculated.     

Spectrophotometric Determination of Esomeprazole Magnesium in Commercial Tablets Using 5‐Sulfosalicylic Acid and N‐Bromosuccinimide

Two simple, sensitive and economical spectrophotometric methods have been developed for the determination of esomeprazole magnesium in commercial dosage forms. Method A is based on the reaction of esomeprazole magnesium with 5‐sulfosalicylic acid in methanol to form a yellow product, which absorbs maximally at 365 nm. Method B utilizes the reaction of esomeprazole magnesium with N‐bromosuccinimide in acetone‐chloroform medium to form α‐bromo derivative of the drug peaking at 380 nm. Under the optimized experimental conditions, Beer's law is obeyed in the concentration ranges of 2‐48 and 10‐100 μg mL^?1 with molar absorptivity of 2.11 × 10⁴ and 4.57 × 10⁴L mol^?1 cm^?1 for methods A and B, respectively. The limits of detection for methods A and B are 0.35 and 0.46 μg mL^?1, respectively. No interference was observed from excipients commonly present in tablet formulations. Methods A and B are successfully applied to the commercial tablets for the estimation of esomeprazole magnesium with good accuracy and precision. The results compare favorably with the reference spectrophotometric method indicating no significant difference between the methods compared.     

New Spectrophotometric Methods for Microdetermination of Fluoxacillin and Cloxacillin in Pure and Dosage Forms

 Two simple, rapid and sensitive methods for the microdetermination of penicillin derivatives are described. The studied compounds are fluoxacillin and cloxacillin. The methods are based on the reaction of these drugs as n-electron donors with either 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) or 7,7, 8,8-tetracyanoquinodimethane (TCNQ) as π-acceptors, to give a highly coloured radical anion. The coloured products were quantified spectrophotometrically at 460 and 840 nm for DDQ and TCNQ, respectively. The proposed methods were applied successfully to the determination of the two penicillins investigated, either in pure or dosage forms, with good accuracy and precision. The results were compared with those given by the official method. Received December 15, 2000. Revision July 10, 2001.     

Spectrophotometric Determination of Copper in Natural Waters and Pharmaceutical Samples with Chloro(Phenyl) Glyoxime

A simple method for the determination of trace amounts of copper by spectrophotometry is described based on the formation of the copper‐chloro‐(phenyl) glyoxime complex. The molar absorptivities of the complexes at pH 4.0 at 290.5 nm were 0.8 × 10⁴l/mol cm. Optimal conditions such as reagent amounts and pH for the copper determination were reported. The effects of the foreign ions were also investigated. The method was successfully applied for determinations of copper in some natural waters and pharmaceutical samples.     

Spectrophotometric Determination of U(VI) with Rifampicin in Soil Samples

A validated spectrophotometric method has been developed for the determination of uranyl ion in soil samples. The method is based on the complexation reaction between uranyl ion and rifampicin in methanol‐water medium at room temperature. The method is followed spectrophotometrically by measuring the absorbance at 375 nm. Under the optimized experimental conditions, Beer's law is obeyed in the concentration range of 1.35–20.25 μg mL^‐1 with apparent molar absorptivity and Sandell's sensitivity of 8.0 × 10³ L mol^‐1cm^‐1 and 0.042 μg/cm²/0.001 absorbance unit, respectively. The interference of a large number of anions and cations has been investigated and the optimized conditions developed have been utilized for the determination of uranium(VI) in soil samples. The three sigma detection limit (n = 9) for uranyl ion was found to be 0.20 μg mL^‐1. The proposed method was successfully applied to the determination of uranyl ion in soil samples.     

A Novel Spectrophotometric Method for the Determination of Zolmitriptan in Pharmaceutical Formulations

A simple, rapid, cost effective and extraction‐free spectrophotometric method has been developed for the determination of zolmitriptan in pharmaceutical raw and dosage forms. The method is based on the charge‐transfer reaction of zolmitriptan in acetonitrile medium with 0.2% 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone to form a colored product peaking at 555 nm. Beer's law is obeyed in the concentration range 10‐250 μg mL^?1 with molar absorptivity of 1.7 × 10³ L mole^?1 cm^?1. The effects of variables such as reagent concentration, time of reaction, color stability and interferences have been investigated to optimize the procedure. The results have been validated analytically and statistically. The proposed method has been successfully applied for the determination of zolmitriptan in pharmaceutical formulations. Results indicate that the method is accurate, precise and reproducible (relative standard deviation < 2%).     

Electrochemical Evaluation of Nucleoside Analogue Lamivudine in Pharmaceutical Dosage Forms and Human Serum

Lamivudine (LAM) is a synthetic nucleoside analogue with activity against human immunodeficiency virus‐type 1 (HIV‐1) and Hepatitis B virus (HBV). The aim of this study was to determine LAM levels in serum and pharmaceutical formulations, by means of electrochemical methods using hanging mercury drop electrode (HMDE). On this electrode, LAM undergoes irreversible reduction at the peak potential near E_p?1.26 V (vs. Ag/AgCl/3 M KCl). Reduction LAM signals were measured by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and square‐wave voltammetry (OSW). DPV and OSW techniques for the determination of LAM in acetate buffer at pH 4.5, which allows quantitation over the 4×10^?6 to 1×10^?4 M range in supporting electrolyte for both methods, were proposed. The linear response was obtained in acetate buffer in the ranges of 2×10^?6 to 2×10^?4 M for spiked serum samples at pH 4.5 for both techniques. The repeatability and reproducibility of the methods for all media were determined. The standard addition method was used in serum. Precision and accuracy were also checked in all media. No electroactive interferences from the endogenous substances were found in serum. With respect to side effects of high doses and short half‐life of LAM, a fast and simple detection method is described in this study.