Separation of Structurally Related Anthocyanins by MEKC

Summary

A method based on micellar electrokinetic chromatography has been developed for the simultaneous separation of six anthocyanins (malvidin-3,5-diglucoside, malvidin-3-glucoside, malvidin-3-galactoside, pelargonidin-3-glucoside, cyanidin-3,5-diglucoside, cyanidin-3-galactoside). Optimum selectivity was achieved in the buffer 30 mM phosphate + 400 mM borate-TRIS, pH=7.0 supported with 50 mM sodium dodecylsulphate. High content of borate was essential mainly for the separation of diastereomeric pair malvidin-3-glucoside-malvidin-3-galactoside. The calibration dependencies exhibit good linearity in the ranges of concentration 10–100 μg mL⁻¹ for diglycosylated and 25–100 μg mL⁻¹ for monoglycosylated derivatives (R² = 0.9711−0.9989). The optimized method was applied to a sample of wine grape skin extract. Malvidin-3-glucoside was identified as main anthocyanin colorant in this sample.