Titrimetric and modified spectrophotometric methods for the determination of amlodipine besylate using bromate-bromide mixture and two dyes.

摘要

One direct titrimetric method and two indirect spectrophotometric methods for the detn. of amlodipine besylate (ADB) are described. The methods use bromate-bromide mixt. and two-dyes, namely Methyl orange and Indigo Carmine, as reagents. In titrimetry (Method A), an acidified soln. of ADB is titrated directly with bromate-bromide mixt. using methyl orange as an indicator. Spectrophotometry involves the addn. of known excess of bromate-bromide mixt. to an acidified soln. of ADB and the detn. of the residual bromine based on its ability to bleach the dyes Methyl orange (Method B) or Indigo Carmine (Method C) quant. Titrimetry allows the detn. of 1-10 mg of ADB, whereas spectrophotometry is applicable over the concn. ranges of 0.5-3.0 μg ml-1 and 1.25-12.50 μg ml-1 for method B, and method C, resp. Method B with a calcd. molar absorptivity of 6.56×104 mol-1 cm-1, is the most sensitive method ever developed for ADB. The limits of detection and quantification are reported for both the spectrophotometric methods. The methods described could usefully be applied to routine quality control of tablets contg. ADB. No interference was obsd. from common pharmaceutical adjuvants. Statistical comparison of the results with the ref. method shows an excellent agreement, and indicates no significant difference in accuracy and precision. The reliability of the methods has been ascertained by recovery studies. [on SciFinder(R)]