Protocatechuic aldehyde (PAL) is a major polyphenolic active ingredient with a variety of biological activities. Herein, the oxidation behavior and mechanism of PAL were studied using different electrode surfaces, and it was found that two-electrons were transferred. Moreover, the silica gel-modified carbon paste electrode (CPE) gave rise to a higher oxidation signal to PAL relative to the unmodified CPE, and a further signal enhancement was observed on the activated silica gel-modified CPE. Based on the remarkable surface enhancement effects of activated silica gel, a new electrochemical method with high sensitivity was developed for the determination of PAL. The linear range was from 5 to 250 μg L−1, and the detection limit was 3.24 μg L−1 (23 nM) after 1 min accumulation. The proposed method was applied in Xiangdan injection samples, and the results were consistent with the values obtained by high-performance liquid chromatography.
