The chromatographic separation of the compounds was carried out at room temperature with a Lichrospher Diol column (5 μm, 4 mm × 250 mm) and detection was performed in an evaporative light scattering detector (ELSD) at 35 °C and 0.35 MPa. Gradient elution was achieved by mobile phases A (isooctane) and B (methyl tert-butyl ether/acetic acid, 99.9:0.1, v/v)