An electrochemical sensor based on carbon paste modified with polyethyleneimine was
developed and employed for the determination of caffeic acid in aromatic herbs. The sensor
was prepared by mixing polyethylenimine (1.5% v/v), graphite powder, and mineral oil. The
polyethylenimine-based electrode showed an enhancement of charge transfer at the
electrode–solution interface and a higher current intensity for the electrochemical reaction of
caffeic acid, in comparison to the unmodified electrode. The calibration plot of caffeic acid …