Application of sulphanilamides disazo dyes with Tropaeolin O for simple, rapid and sensitive spectrophotometric assay of medicines

A rapid, simple and sensitive spectrophotometric method for the determination of some sulphanilamides is described. The method is based on the formation of blue coloured disazo dyes by the diazotization of sulphonamides viz. sulphanilamide (SA), sulphamerazine (SMR), sulphamethazine (SMZ), sulphadimethoxine (SDM), sulphamethoxazole (SMX), sulphadiazine (SDA), sulfathiazole (STZ), sulphaguanidine (SGN), sulphamonomethoxine (SMM), sulphamethoxypyridazine (SMP) in 0.5 M hydrochloric acid media at ice bath followed by the azocoupling reaction with acid monoazo dye Tropaeolin O (TrO) at pH = 10.5. Formed products are stable for 10 h at room temperature. Effective molar absorptivities at absorbance maxima 595 nm for disazo dyes were ∼104 M−1 cm−1. Stoichiometric ratios of the components of disazo dyes were determined by means of mole ratio and continuous variations methods. Linear ranges for sulphanilamides determination were 0.4–14.0 μg ml−1. The methods were successfully approved at suphanilamides determination in model solutions and commercial pharmaceutical preparations.

The rapid, simple and sensitive spectrophotometric method is based on the formation of blue coloured disazo dyes by the diazotization of sulphanilamides.Figure optionsDownload as PowerPoint slideHighlights
► A rapid, simple and sensitive spectrophotometric method for the determination of 10 sulphanilamides.
► Formation of blue coloured disazo dyes by the azocoupling reaction of diazotized of sulphonamides with acid monoazo dye Tropaeolin O.
► The influence of heterocycle substituent nature as well as substituents number on the sensitivity of SA determination with Tropaeolin O.
► Assay of sulphadimezine, sulphadimethoxine, sulphanilamide quantity in tablets “Streptocidum”, “Sulfadimesinum”, “Sulfadimethoxine” accordingly.