Table 1 Optimized chromatographic conditions

Column

Symmetry C₁₈ (150 mm × 4.6 mm, 5 μm)

Mobile phase

Methanol: Potassium Dihydrogen Phosphate buffer: Acetonitrile (60: 35: 05% v/v/v)

pH 3 adjusted with OPA

Flow rate

1 mL/min

Temperature

25 °C

Injection volume

20 µL

Detection wavelength

240 nm

Diluent

Methanol

Run time

10 min

Retention time

FIK: 2.65 min. & CLN: 5.51 min