Rapid and sensitive electrochemical determination of flavonoids in Albanian wines using zeolite X and Prrenjasi clay as carbon paste modifiers

This study investigated the electrochemical determination of flavonoids in Albanian wines using carbon paste electrodes modified with various materials. We employed an ex-situ method to minimize interferences from complex wine matrices, focusing on catechins as flavonoids representatives. The modifiers included Zeolite type X, and clay from the Prrenjasi region in Albania. Differential pulse voltammetry, cyclic voltammetry, electro­chemical impedance spectroscopy, and scanning electron microscopy were utilized to characterize the modified electrodes. Results indicated that the carbon paste electrode modified by Prrenjasi clay (PCME) exhibits the highest sensitivity, with the lowest electron transfer resistance and largest active surface area. Also, PCME was chosen for its linear background, low cost, and excellent sensitivity for total flavonoid determinations in Albanian wines. The method demonstrated a limit of detection of 99.3 nM and a limit of quantification of 331 nM. The catechin equivalent flavonoids in the analysed Albanian wine samples ranged between 513.13 and 2156.07 mg L⁻¹. The diffusion coefficient of catechin was determined to be 1.38×10-⁵ cm² s-1. A comparative analysis was also performed using UV-VIS spectrophotometry, which determined the total flavonoid content in each analysed wine. The study demonstrated the potential of using PCME carbon paste electrodes for reliable flavonoid quantification in Albanian wines.