Spectrophotometric Determination of Teicoplanin via Coupling with Diazotized p-Nitroaniline

A new, simple and sensitive spectrophotometric method was described for the determination of teicoplanin as a pure material and in pharmaceutical formulation. The method is based on the coupling of teicoplanin with diazotized p-nitroaniline in alkaline medium. The dye shows an absorption maximum at 490 nm and obeys Beer's law over a range of 2 to 80 g.ml.-1 of teicoplanin. The molar absorptivity of the coloured azo dye is 2.8 x 104l. mol-1cm-1. The relative standard deviation does not exceed 2.7 % (n=5). The azo dye formed is stable for 60 minutes. The method was applied successfully to the assay of teicoplanin in pharmaceutical preparation (injection).