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Abstract

Two rapid assay procedures based on visible spectrophotometry and high performance liquid chromatography (HPLC) have been developed for the determination of amlodipine besylate (ADB) in pharmaceutical formulations. Spectrophotometric method is based on the bromination of ADB with a known excess of bromate-bromide mixture in acid medium followed by the determination of surplus bromine by reacting with Metanil Yellow and measuring the absorbance at 530 nm. The HPLC determination was carried out on a reversed phase C 18 column using 0.1% orthophosphoric acid (pH 3): acetonitrile (20:80) at a flow rate of 1.0 ml min -1 with UV-detection at 238 nm. In the spectrophotometric method, the absorbance is found to increase linearly with increasing concentration of ADB, which is corroborated by the calculated correlation coefficient of 0.9975. The system obeys Beer' s law for 1.25-7.50 µg ml -1 ADB with a molar absorptivity of 2.51 x 10 4 l mol -1 cm -1 and a Sandell sensitivity of 16.37 ng cm -2 . The limits of detection and quantification are calculated to be 0.17 and 0.56 µg ml -1 , respectively. In the HPLC method, a rectilinear relationship was observed between 7.55 -241.6 µg ml -1 ADB with a detection limit of 1.51 µg ml -1 and a quantification limit of 3.02 µg ml -1 . The statistical evaluation of the methods was examined by determining intra-day and inter-day precision. The methods, when applied to the determination of ADB in tablets, gave satisfactory results. Accuracy and reliability of the proposed methods were further ascertained by parallel determination by the reference method and by recovery studies.

Recent developments in analytical determination of furosemide

“…The titration is performed with 0.025 M KOH aqueous solution and the equivalent point was determined from the differential titration curve or by addition of bromothymol blue solution until to the emulsion colour changed from yellow to blue [7]. Recently, an acidified solution of FUR is titrated directly with bromate-bromide mixture using methyl orange as indicator and applicable over 2-20 mg range [8].…”

“…Bulk drug and formulations [8] Fe(III) and ferricyanide(III) Based on a redox reaction; resulting Prussian blue measured at 760 nm…”

“…Bulk drug and formulations [18] Cu(II) At pH 3.2 using Mclivaine buffer solution to produce a green adduct; at 790 nm Linear range of 5-30 g mL −1 ; detection limit 0.23 g mL −1…”

Titrimetric, spectrophotometric and kinetic methods for the assay of atenolol using bromate-bromide and methyl orange

“…[46][47][48][49] Gyory 50 used methyl orange as the indicator in the direct titration with bromate-bromide solution, the drug being irreversibly bleached at the end point. Many acid dyes are prone to oxidation to form colourless products in acid medium thus offering a suitable analytical approach for the indirect assay of oxidisable pharmaceuticals 41-49 using various oxidizing agents, including the bromate-bromide reagent.…”

“…The bleaching action of bromine on methyl orange has been successfully utilized for the kinetic determination of organic pharmaceuticals, such as albendazole, 46 famatodine, 47 salbutamol sulphate, 48 propranolol, 49 paracetamol, 50 stilbestrol, 51 phenylephrine hydrochloride, 52 salicylamide and tetracline hydrochloride 53 and ascorbic acid. The bleaching action of bromine on methyl orange has been successfully utilized for the kinetic determination of organic pharmaceuticals, such as albendazole, 46 famatodine, 47 salbutamol sulphate, 48 propranolol, 49 paracetamol, 50 stilbestrol, 51 phenylephrine hydrochloride, 52 salicylamide and tetracline hydrochloride 53 and ascorbic acid.…”