Development and Validation of Analytical Method for Losartan-Copper Complex Using UV-Vis Spectrophotometry

Purpose: To develop a new spectrophotometric method for the analysis of losartan potassium in pharmaceutical formulations by making its complex with copper.
Method: A coloured complex based on UV/Vis spectroscopic method was developed for the determination of losartan potassium concentration in pharmaceutical formulations in the visible region. The colored complex of losartan was formed with cupric acetate (5:4). Analysis was carried out by the two methods - absorption ratio and calibration curve methods. The proposed method was validated in terms of linearity, accuracy and precision.
Results: The λ maximum of the complex was recorded at 530 nm. Beer`s law was obeyed in the range of 10 - 50 μg/ml with a correlation coefficient (r²) of 0.9989. Mean analytical results from the calibration curve and absorption ratio methods were 99.42 and 99.16 % with relative standard deviation (RSD) of 0.97 and 0.82 %, respectively. Mean recovery was between 98.61 and 101.35 % and precision expressed as relative standard deviation (RSD) was 0.91 %.
Conclusion: The proposed method is simple, easy to apply, low-cost, and requires relatively inexpensive instruments. Thus, it is a suitable alternative to currently used spectrophotometric methods for the determination of losartan in bulk and solid dosage forms.