Sensitive and spectrophotometric methods for the determination of Azathioprine in tablets using indigo carmine and methyl orange

A simple, economical, precise and fast visible spectrophotometric method has been developed for the determination of Azathioprine in tablet dosage form. Developed method is based on the formation of extractable colored complex of drug with colouring agent Indigo Carmine and Methyl orange. A wavelength maximum was found to be 683.7 nm and 566 nm. The concentration range of 15-50 μg mL-1 with of percentage recovery 100.05-101.31 %, while the linear regression, LOD and LOQ were 99.42-99.08 %, 0.38 and 0.84 μg mL-1 and 0.74 and 0.18 μg mL-1, respectively. Two new sensitive spectrophotometric methods are proposed for the determination of Azathioprine using bromate-bromide mixture and two dyes, methyl orange and indigo carmine, as reagents. The methods entail the addition of a known excess of bromate-bromide mixture to Azathioprine, in acetic acid medium followed by determination of residual bromine by reacting with a fixed amount of either indigo carmine and measuring the Absorbance at 683.6 nm (Method A) or methyl orange measuring the absorbance at 566 nm (Method B).