Fast simultaneous quantitation of valsartan and amlodipine besylate using an eco-friendly micellar HPLC-UV method: application to spiked human plasma and content uniformity testing for amlodipine

Abstract

A simple, sensitive, and cost effective quantitation of two commonly co-formulated antihypertensive medications, valsartan (VAL) and amlodipine besylate (AML) was carried out simultaneously in less than 4 minutes. The developed method was performed with a monolithic stationary phase kept at ambient temperature using an eco-friendly micellar mobile phase consisting of an aqueous solution of 0.16 M sodium dodecyl sulphate (SDS), 0.3% triethylamine (TEA) and 15% n-propanol, adjusted to pH 2.5 using orthophosphoric acid and pumped at a flow rate of 2 mL min⁻¹. Clopidogrel (CLP) was used as an internal standard (IS) and the detection wavelength was 240 nm. The linearity ranges were found to be 5.0–300.0 μg mL⁻¹ and 5.0–200.0 μg mL⁻¹ with limits of detection (LODs) of 0.15 and 0.14 μg mL⁻¹ and limits of quantitation (LOQs) of 0.50 and 0.47 μg mL⁻¹ for VAL and AML, respectively. Application of the proposed method to the simultaneous analysis of VAL and AML in their laboratory synthetic mixture and co-formulated tablets was carried out and the results were satisfactory. The method sensitivity permitted the determination of AML in spiked human plasma without tedious extraction steps owing to the presence of the micellar mobile phase. The method was additionally applied to content uniformity testing of AML adopting official guidelines. Statistical assessment of the obtained data proved good accuracy and precision of the designed method in comparison with the official one.