Spectrophotometric determination of isoniazid with sodium 1,2-naphthoquinone-4-sulphotlate and cetyltrimethyl ammonium bromide

A rapid, sensitive and simple spectrophotometric method is developed for the determination of isoniazid (INH) with sodium 1,2-naphthoquinone-4-sulphonate and cetyltrimethyl ammonium bromide (CTA) in alkaline medium. Beer's law is obeyed in the range of INH concentrations of 2-5.6 mu g ml(-1) at the maximum absorption of 500 nm. Sensitivity is enhanced by the addition of CTA. The method is successfully employed for the determination of INH in various pharmaceutical preparations and common excipients used as additives in pharmaceuticals do not interfere in the proposed method