Application of 3-methylbenzothiazolin-2-one hydrazone as a chromogenic reagent for the spectrophotometric determination of certain sulpha drugs

Abstract

The oxidative coupling reaction of 3-methylbenzothiazolin-2-one hydrazone with aromatic amines was applied to the determination of seven pharmaceutical sulphonamides containing a primary aromatic amino group. A mixture of an acidic solution of the sulphonamide and the chromogenic reagent was treated with ammonium iron(III) sulphate. The wavelengths of maximum absorption are from 565 to 620 nm and the molar absorptivities range from 2.18 × 10³ to 6.32 × 10³ l mol^–1 cm^–1. A linear correlation was found between absorbance at λ_max. and concentration. The procedures developed for bulk sulpha drugs and some of their dosage forms are rapid, accurate, precise and comparable to the Bratton-Marshall procedure. The method is also applicable to blood and urine samples.