Spectrophotometric quantification of Atomoxetine hydrochloride based on nucleophilic substitution reaction with NQS

Objectives:
A simple, sensitive, selective and cost effective colorimetric method has been entrenched for the quantitative estimation of Atomoxetine hydrochloride in bulk and formulation.
Materials and methods:
It was established based on the visible reaction between Atomoxetine hydrochloride and 1,2-naphthoquinone-4-sulfonic acid sodium salt in basic medium (potassium hydroxide). The resulting orange colored chromogen exhibited absorption maximum at 474 nm.
Results
Based on the optimization studies, distilled water as solvent, 1% w/v of potassium hydroxide (2 mL) and 0.3% w/v of 1,2-naphthoquinone-4-sulfonic acid sodium salt (2 mL) were utilized in the method. The developed method was validated as per International Council for Harmonization guidelines. The linearity was found to be in concentration of 10-50 µg/mL. The method appeared to show a good correlation between concentration of Atomoxetine hydrochloride and its absorbances. The correlation coefficient (r2) of 0.999 evidenced the same. The limit of detection and quantification were observed as 0.20 and 0.606 µg/mL, respectively for Atomoxetine hydrochloride. Accuracy and precision of the method were also evaluated, the results obtained were within the acceptance criteria (% relative standard deviation < 2.00). The % assay of Atomoxetine hydrochloride was proved to be 101.52, which is in accord with its label claim.
Conclusion
The developed method was non-complex and can be effectively employed in the analytical practices of Atomoxetine hydrochloride in pharmaceutical dosage forms.