Green micellar HPLC-fluorescence method for simultaneous determination of metoprolol and amlodipine in their combined dosage form: Application on metoprolol in spiked human plasma

A fast, sensitive and reliable green micellar liquid chromatographic method has been developed and validated for simultaneous determination of metoprolol (MET) and amlodipine (AMD). Separation was performed on X-Bridge ODS column (150 x 4.6 mm, 5 mu m particle size) using a micellar mobile phase consisting of 100 mM sodium dodecyl sulfate, 20 mM sodium dihydrogen phosphate buffer pH 3.0 and 10% v/v n-butanol. The fluorescence detector was set at 275/ 303 nm (excitation/ emission) for MET and 364/ 455 nm (excitation/emission) for AMD. A linear response was obtained over the ranges of 0.1-10 mu g/mL and 0.2-2 mu g/mL for MET and AMD, respectively. The method reached limits of detection of 20 ng/mL for MET and 50 ng/mL for AMD. The proposed method was successfully employed for the determination of the two drugs in their combined pharmaceutical dosage form and in addition, it was extended for the determination of MET in spiked human plasma. Furthermore, the green character of the developed method was evaluated using the new tool "green analytical procedure index (GAPI)". The developed method was verified to be an excellent green method.