Spectrophotometric Quantification of Atomoxetine Hydrochloride Based on Nucleophilic Substitution Reaction with 1,2-Naphthoquinone-4-Sulfonic Acid Sodium Salt (NQS)

A simple, sensitive, selective, and cost-effective colorimetric method has been established for the quantitative estimation of atomoxetine hydrochloride in bulk and formulation.A simple, sensitive, selective and cost effective colorimetric method has been entrenched for the quantitative estimation of Atomoxetine hydrochloride in bulk and formulation.

It was established based on the visible reaction between atomoxetine hydrochloride and 1,2-naphthoquinone-4-sulfonic acid sodium salt in a basic medium (potassium hydroxide). The resulting orange colored chromogen exhibited an absorption maximum at 474 nm.

Based on the optimization studies, distilled water as the solvent, 1% w/v potassium hydroxide (2 mL), and 0.3% w/v 1,2-naphthoquinone-4-sulfonic acid sodium salt (2 mL) were used in the method. The developed method was validated per the International Council for Harmonization (ICH) guidelines. The linearity was found at a concentration of 10-50 μg/mL. The method showed a good correlation between the concentration of atomoxetine hydrochloride and its absorbance. The correlation coefficient (r²) of 0.999 evidenced the same. The limits of detection and quantification were 0.20 and 0.606 μg/mL, respectively, for atomoxetine hydrochloride. The accuracy and precision of the method were also evaluated and the results obtained were within the acceptance criteria (relative standard deviation % < 2.00). The percentage assay of atomoxetine hydrochloride proved to be 101.52, which is in accordance with its label claim.

The developed method is non-complex and can be effectively employed in the analytical practices of atomoxetine hydrochloride in pharmaceutical dosage forms.