Electrochemically synthesized VOSO4-doped polypyrrole on pencil grapHite electrode for highly sensitive dopamine detection in biological and pharmaceutical samples

Abstract

A highly sensitive and low-cost electrochemical dopamine (DA) sensor was developed via one-step electropolymerization of vanadyl sulfate (VOSO4)-doped polypyrrole (PPy) onto a pencil graphite electrode (PGE). Under optimized conditions (pH 6.0, 0.1 M phosphate buffer), the electrode exhibited two linear response ranges of 0.05-100 & micro;M (R2 = 0.9996) and 250-1500 & micro;M (R2 = 0.9963). The analytical performance parameters were LOD = 0.03 & micro;M, LOQ = 0.11 & micro;M, and RSD = 3.48%, indicating high sensitivity and good repeatability. The electrode retained 94.0% of its initial current response after 25 days, demonstrating satisfactory storage stability. Real sample analysis provided recovery values of 97.39% (pharmaceutical tablet), 99.96% (human serum), and 97.26% (human urine), confirming the applicability of the sensor in complex matrices. The enhanced electrochemical response is attributed to the conductive PPy matrix and the redox-active V4+/V5+ centers, which facilitate charge transfer and electrocatalytic activity. Overall, the PGE/PPy/VOSO4 electrode offers a low detection limit, broad linear range, good reproducibility, and low fabrication cost, making it a promising platform for dopamine determination in pharmaceutical and biological samples.