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|Title:||Sensitive titrimetric and spectrophotometric methods for the assay of lamivudine in pharmaceuticals|
Somashekar, B C
|Abstract:||One titrimetric and two spectrophotometric methods are described for the assay of lamivudine in bulk drug and in tablets using bromate-bromide mixture and two dyes, methyl orange and indigocarmine, as reagents. In titrimetry, aqueous solution of lamivudine is treated with measured excess of bromate-bromide mixture in HCl medium, followed by iodometric determination of unreacted bromine. Spectrophotometric methods involve the addition of a known excess of bromate-bromide mixture to lamivudine in acid medium, followed by the determination of residual bromine by reacting with either a fixed amount of methyl orange and measuring the absorbance at 520 nm (Method A) or indigocarmine and measuring the absorbance at 610 nm (Method B). In all the methods, the amount of bromate reacted corresponds to the amount of lamivudine. Titrimetric method is applicable over 2.5-7.5 mg range and the reaction stoichiometry is found to be 1:1 (lamivudine: KBrO<sub>3</sub>). In spectrophotometric methods, absorbance is found to increase linearly with concentration of lamivudine, which is corroborated by the correlation coefficient of 0.9971 and 0.9999 for method A and method B, respectively. The systems obey Beer’s law for 0.125-1.50 mg/ml (Method A) and 1.0-8.0 mg/ml (Method B). The calculated apparent molar absorptivity values are found to be 7.4 X 10<sup>4</sup> and 1.7 X 10<sup>4</sup> l mol<sup>-1</sup> cm<sup>-1</sup>, for method A and method B respectively, and the corresponding Sandell sensitivity values are 3.10 and 13.52 ng/cm<sup>2</sup>. The limits of detection and quantification are also reported for both spectrophotometric methods. Intra-day and inter-day precision and accuracy of the methods have been evaluated. The methods were successfully applied to the assay of lamivudine in tablet preparations and the results were compared with those of a reference method by applying Student’s t and F-tests. No interference was observed from common pharmaceutical adjutants. The reliability of the methods was further ascertained by performing recovery tests by standard addition method.|
|ISSN:||0975-1084 (Online); 0022-4456 (Print)|
|Appears in Collections:||JSIR Vol.65(04) [April 2006]|
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