Spectrophotometric Determination of Rifampicin by the Color Reaction of Victoria Blue B

In a Tris-HCl buffer solution of pH 6.92, a complex was formed by the reaction of rifampicin with victoria blue B, having its absorption maximum at the wavelength of 562 nm. Beer′s law was kept in the range within 8.0×10-6mol· L-1, with apparent molar absorptivity of 1.86×105L·mol-1·cm-1. The proposed method was used in the determination of rifampicin in its capsules, and the results obtained were in conformity with the labeled values. Values of recovery found by standard addition method were in the range of 98.2%-100% with RSD′s (n=6) less than 1.5%.