HPLC-DAD identification of compounds in corrosion inhibitor Salix alba bark extract and the hydrolate

Abstract

The compounds present in Salix alba bark (SAB) extract and its hydrolate were identified using high performance liquid chromatography with diode array detection (HPLC-DAD). SAB extract and its hydrolate were obtained by evaporating a macerate of dried, ground white willow bark and hot distilled water. A total of 19 standard polyphenolic compounds were used for the HPLC analysis. Results indicate that only 4-hydroxybenzoic acid (4-HBA) was detected in the SAB hydrolate. In contrast, both gallic acid and caffeic acid were present in the SAB extract. The presence of 4-HBA indicates the potential possibility of using SAB hydrolate as a starting component for the synthesis of parabens and other 4-HBA derivatives. Additionally, the identification of gallic and caffeic acids in the SAB extract further confirms the effect as a cathodic inhibitor of copper corrosion in chloride environments, because both acids are proven cathodic inhibitors of copper in different corrosion environments