Study of the scale isolation of anthocyanins from blue corn by flash chromatography

Abstract In the current work, a flash chromatography method was developed to separate the main anthocyanins of blue corn; cyanidin-3-glucoside (Cy3G), peonidin-3-glucoside (Pn3G), and cyanidin-3-(6-malonylglucoside) (Cy3MG). These anthocyanins were identified by mass spectroscopy analysis. The implemented method consisted of the isocratic elution in a two-step mixture of methanol: water: acetic acid as the mobile phase (easy to remove) and C18 resin as the stationary phase. In the chromatographic method, different elution conditions were evaluated. The better condition to separate the anthocyanins with glycoside was 5% methanol and 10% acetic acid for 200 minutes of elution, followed by 200 minutes with 25% methanol and 2.5% acetic acid for the malonylglucoside forms. From the chromatograms prepared, the efficiency of the chromatographic separation was evaluated by calculating the parameters: retention factor ( ), selectivity ( ), number of theoretical plates ( ), and resolution ( ). The optimal values were determined as follows: Cy3G and Cy3MG were as follows: for Cy3G, the rretention factir (k) was dtermined to be 30.2, the selectivity (α) was 1.55, the number of theorical plates (N) was 202, and the resolution (Rs) was 1.09. For Cy3MG, the corresponding values were; k = 104.9, α =1.21, N=522, and Rs 0.093. These parameters are useful to implement separation processes of anthocyanins from other sources of pigmented corn or even others containing anthocyanins. Graphical abstract