Fig. 4

Chromatograms obtained using different mobile phase flow rates i 1.2 mL min⁻¹, ii 0.5 mL min⁻¹ and iii 1.0 mL min⁻¹. The mixed standard chromatogram results found based on the optimized parameters, mobile phase: 0.05 Na₂HPO₄:ACN:MeOH (70:10:20), pH 8, temperature: 40 °C, wavelength: 230 nm, and flow rate: 1 mL min⁻¹