Comparison of anthocyanin distribution in different blueberry sources by capillary zone electrophoresis

Capillary zone electrophoretic separation of blueberry anthocyanins was studied using a Na-borate buffer containing trans-1,2-diaminocyclohexane-N,N,N',N'-tetra acetic acid monohydrate (CyDTA) as the carrier buffer. The separation conditions were precisely examined using an aqueous extract of bilberry (wild type blueberry) as the separation sample which is rich in this type and amount of anthocyanins. Each separated peak was identified by comparing the mobility with that of anthocyanin standards after normalization against the mobility of malvidin 3-o-glucoside (Mv 3-Glc) added as an internal standard. As salt concentrations of the running buffer increased, the peak resolution was markedly improved over the whole range of separation, especially, among the fast moving components (petunidin 3-glucoside, cyanidin 3-glucoside and malvidin 3-galactoside). Inversely, the peak separation both between petunidin 3-glucoside and peonidin 3-glucoside, and between delphinidin 3-glucoside and petunidin 3-galactoside, respectively, were decreased. The anthocyanins were, however, successfully separated by decreasing the buffer pH. Good separation of anthocyanins was finally achieved by 30 mM Na-borate (pH 8.78) containing 7.5 mM CyDTA within 10 min. Under this separation condition, anthocyanins from different blueberry sources were analyzed. The results revealed that different blueberry sources had their own patterns of anthocyanin distribution and amounts in the extracts, thus the present method is suitable for the quality control of anthocyanin-containing food materials.