Figure 3a: Van Deemter plot for Sequant ZIC HILIC column (5 μm, 150 mm × 2.1 mm i.d.), Column temperature: 40°C; UV: 254 nm. The mobile phases used were- 50 mM ammonium acetate: acetonitrile (95:5 v/v) and 50 mM ammonium acetate: water: acetonitrile (50:45:5 v/v). The gradient program is described in Table 1.