Four simple and sensitive spectrophotometric methods were proposed for determination of
secnidazole in pure and in tablet forms. The methods (I, II, III) depends on the reduction of
secnidazole molecule with zinc dust and hydrochloric acid), forward by coupling reaction between
the drug and vanillin reagent in acidic condition (method I), the red colored product was measured
atmax 557 nm. Beer's law was obeyed in the range 5-55 μg/ml. Method II, 1, 2-Naphthoquinone-4-
sulphonate sodium react in alkaline media through nucleophilic substitution reaction producing an
orange-brown colored product showing maximum absorption at 480 nm. Beer's law was obeyed in
the range 0.2-2.2 μg/ml. Method III, charge transfer complex was formed with tetracyanoethylene
with maximum absorbance at 397 nm. Beer's law was obeyed in the range 0.15-1.2 μg/ml.
Method IV based on bromination-oxidation reaction using bromate-bromide mixture with
methyl orange as reagent and measuring the absorbance of the unbleached dye at 510 nm. Beer's
law was obeyed in the range 3-8 μg/ml.
Under optimized conditions, the methods were applied successfully to the tablets containing
secnidazole. The results obtained are in good agreement with those obtained using official and
reference methods.