Application of Metanil Yellow for the Extractive Spectrophotometric Determination of Norfluoxetine

A simple, fast, precise extractive spectrophotometric method has been developed for the estimation of Norfluoxetine in urine. The method was based on the formation of ion-pair complex of the drug with metanil yellow in acidic medium and the subsequent extraction of the ion-pair in chloroform. The concentration of Norfluoxetine over a range of 2-12 μg/ml was found to obey Beer’s law in the stated range. The yellow colored complex has absorption maxima at 405 nm with molar absorptivity and sandell’s sensitivity 2.2387×10⁴ lit mol^-1cm^-1 and 0.0154 μg/cm²/0.001 absorbance unit, respectively. The optimum quantity and reagent composition for metanil yellow was found to be 2 ml and 0.02% w/v in pH 2.4 buffer. The proposed method is highly sensitive, specific and the reagent was not found to react with the soluble matters of the body fluids like plasma and urine. The results of analysis where validated as per ICHQ2B guidelines.