3D-printed electrochemical cell for both detection and degradation of venlafaxine and desvenlafaxine with boron-doped diamond electrode

Abstract

Venlafaxine (VF) and its active metabolite desvenlafaxine (DVF) are widely prescribed antidepressants that are only partially metabolized and excreted in significant amounts, making them clinically important analytes and environmentally relevant contaminants. In this study, a free-standing boron-doped diamond (BDD) electrode is exploited in a dual role for the electrochemical detection and degradation of VF and DVF, integrated into a custom 3D-printed dual-function electrochemical cell. The nucleation (BDD_NS) and growth (BDD_GS) sides of the BDD plate were systematically compared under different surface terminations. Oxidized BDD_NS (O-BDD_NS) provided three well-resolved oxidation peaks for VF, whereas hydrogen-terminated BDD_NS (H-BDD_NS) yielded a single distinct peak for DVF in 0.1 M H₂SO₄. Differential pulse voltammetric (DPV) methods were developed with limits of detection of 0.35 µM for VF (peak 1) and 0.34 µM for DVF and wide linear ranges in the low-to-high micromolar region. By exploiting the different surface-termination preferences and multi-peak behaviour of VF, simultaneous determination of VF and DVF was achieved. The methods showed good selectivity toward common interferents and were successfully applied to spiked river water and pharmaceutical capsules using the standard addition approach, giving recoveries close to 100 %. In the 3D-printed cell, BDD_GS was used for electrochemical advanced oxidation, achieving ∼97 % degradation of 1 mM VF and DVF in 0.1 M H₂SO₄ within 20 min under galvanostatic conditions, following pseudo-first-order kinetics. In situ DPV on BDD_NS enabled real-time monitoring of VF decay, demonstrating an integrated detect-and-degrade platform based on BDD and additive manufacturing.