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7570285 
Journal Article 
Development and validation of oxidative assay methods for metaprolol tartrate in pharmaceuticals using chloramine-T and two dyes 
Basavaiah, K; Ramakrishna, V; Somashekar, BC 
2007 
77A 
185-194 
WOS:000255026300002 
Titrimetric and spectrophotometric methods for the assay of metaprolol tartrate (MPT) in bulk drug and in tablets are described. The methods employ chloramine-T (CAT) as the oxidimetric reagent and dyes methyl orange and indigo carmine as the spectrophotometric reagents. In titrimetry, an acidified solution of MPT is treated with a measured excess of chloramine-T and after a specified time the unreacted oxidant is determined by iodometric back titration. The spectrophotometric methods involve the addition of measured excess of CAT to MPT in acid medium followed by determination of residual oxidant by reacting with a fixed amount of either methyl orange and measuring the absorbance at 520 nm (method A) or indigo carmine and measuring the absorbance at 610 nm (method B). In all the methods the amount of reacted CAT corresponds to the amount of MPT. Titrimetry is applicable over 1-20 mg range and the calculations are based on a 1:2 (MPT: CAT) reaction stoichiometry. In the spectrophotometric methods the absorbance is found to increase linearly with the concentration of MPT. The systems obey Beer's law for 0.5 - 6.0 and 2 - 20 mu g ml(-1) MPT for method A and method B respectively. The calculated molar absorptivity values are 5.6 x 10(5) and 1.6 x 10(4) l mol(-1) cm(-1) for method A and method B respectively and the corresponding Sandell sensitivity values are 12.19 and 41.92 ng cm(-2). The limits of detection and quantification are also reported for both spectrophotometric methods. The methods have been validated according to ICH guidelines by calculating intra-day and inter-day precision, and accuracy. No interference was observed from common pharmaceutical adjuvants. The reliability of the methods was ascertained by recovery studies via standard addition procedure.