A novel validated UPLC method for quantitation of lopinavir and ritonavir in bulk drug and pharmaceutical formulation with its impurities

A simple gradient Ultra Performance liquid chromatographic method (UPLC) was developed for determination of lopinavir and ritonavir from its related impurities and assay for the first time. This method involves the use of a C18 (Acquity UPLC BEH C18, 50 × 2.1 mm, 1.7 µm) column thermostated at 30 oC using triethylamine (pH 2.2): 0.1% H3PO4 in acetonitrile and methanol (85:15) as mobile phase in gradient elution mode. A Photo Diode Array (PDA) detector set at 215 nm was used for detection with flow rate 0.4 mL/min. This method was validated over the range of limit of quantitation (LOQ) to 50 to 150% of impurity specification limit and of working concentration for assay. The developed method was validated for linearity, range, precision, accuracy and specificity. This method was successfully applied for content determination of lopinavir and ritonavir in pharmaceutical formulations. This method can be conveniently used in quality control laboratory for routine analysis for assay and related substances as well as for evaluation of stability samples of bulk drugs and pharmaceutical formulations