Development of a 2D-HPLC for simultaneous determination of rhynchophylline, isorhynchophylline, corynoxeine and isocorynoxeine

ObjectiveTo develop a two-dimensional high-performance liquid chromatography (2D-HPLC) for simultaneous determination of the contents of four kinds of Uncaria alkaloids: rhynchophylline, isorhynchophylline, corynoxeine and isocorynoxeine. MethodsThe 2D-HPLC apparatus was comprised of a first chromatographic column in version Aston SC2 (3.5 mm×25 mm, 5 μm), an intermediate column in version Aston SH C18 (3.5 mm×10 mm, 5 μm), and an analytical column in version Aston SCB (4.6 mm×125 mm, 5 μm). The mobile phase of the first and second liquid chromatography system were CAA-1 and mixed mobile phase (V BPI-1 basic mobile phase∶ V MPI-1 mobile phase ∶ V OPI-1 organic mobile phase = 45∶14∶41). The chromatographic parameters included a flow rate of 1.0 mL/min, a column temperature of 40℃, a wavelength of 254 nm, an injection volume of 500 μL and a detection time of 9.5 min. ResultsThe linear ranges of rhynchophylline, isorhynchophylline, corynoxeine and isocorynoxeine were 9.77~10 000.00 ng/mL (r=0.999 6), 10.74~11 00