Electrochemical Studies of Polyphenols, Anthocyanins, and Flavonoids Extracted from Blueberry Fruit

This work was carried out for extraction and electrochemical studies of polyphenols, anthocyanins, and flavonoids in blueberry fruit. The conventional extraction (solid-liquid) with hydro-organic solvent system was used to obtain polyphenol compounds extracts from blueberries pomace. The electrochemical and high-performance liquid chromatography (HPLC) techniques were used for identification and determination of the polyphenols, anthocyanins, and flavonoids content in blueberries pomace. For electrochemical analyses, the functionalized CNTs were electrodeposited on glassy carbon electrode (f-CNTs/GCE) and used as a working electrode for study of the polyphenols substances in blueberries pomace. Results of structural and morphological analyses of electrodeposited nanostructure using SEM and XRD demonstrated that f-CNTs on the surface of GCE created a net-like film with porous reticular structure that can facilitate the electron transfer rate. Both electrochemical and HPLC methods showed that quercetin, rutin, delphinidin, cyanidin and gallic acid were observed in extracted polyphenolic compounds. The sensing properties of f-CNTs/GCE as a sensor of polyphenolic compounds were determined by DPV measurements and compared with the HPLC sensing properties in this work and other reported sensors in literature. Results of analytical studies indicated good ranges of recovery (97.05% to 99.10%) for DPV technique and (95.68% to 98.55%) for HPLC technique, and acceptable ranges of RSD (2.12% to 3.20%) for DPV technique and (2.78% to 4.29%) for HPLC technique. The better results for DPV technique using f-CNTs/GCE was implied to appropriate accuracy of proposed polyphenolic compounds sensor for analyses of fruit and food samples.