Aminoterephthalic acid ligand terminated zirconium metal-organic framework/palladium nanoparticles composite for voltammetric determination of syringic acid in wine samples

In this study, we investigated the electrochemical determination of syringic acid using palladium nanoparticles dispersed zirconium metal-organic framework composite. Transmission electron microscopic images illustrated that the average diameter of < 10 nm spherical Pd nanoparticles was decorated on the surface of the metal-organic framework. Cyclic voltammetric analysis showed that the composite exhibited well-defined oxidation (0.61 eV) and reduction (0.48 eV) peaks toward the determination of syringic acid in 0.1 M phosphate buffer saline (pH 3). In addition, the composite electrode demonstrated higher currents than the bare glassy carbon electrode and pure metal-organic framework. The differential pulse voltammetric analysis showed that the composite electrode manifested a dynamic linear range of concentrations from 0.5 to 100 µM with a regression equation of I (µA) = 0.3217x + 5.8055 (R² = 0.9981). The sensitivity and detection limit of the composite electrode were identified as 0.32 µA/µM and 0.17 µM, respectively. The composite electrode demonstrated good anti-interference properties towards benzoic acid, routine, caffeic acid, sinapic acid, and KCl. The composite electrode was used to determine the syringic acid level in wine samples with good recoveries (99 to 103%), indicating its feasibility for practical applications in the pharmaceutical sector.