Development of Electrochemical Microsensors for Phosphate Detection in Aquatic Environments Using a Gold Electrode in a Microfluidic System

Phosphates are key nutrients in aquatic ecosystems (Jiao et al., 2012), but excess concentrations cause eutrophication, degrading water quality and biodiversity. Monitoring phosphate at low levels and in situ is thus essential for environmental protection. This study presents electrochemical microsensors integrated into a microfluidic system for sensitive phosphate detection using Cyclic Voltammetry (CV), Square Wave Voltammetry (SWV), and Differential Pulse Voltammetry (DPV). Two strategies were developed: (1) copper-modified gold electrodes monitoring inhibition of the Hydrogen Evolution Reaction (HER), leading to a limit of detection of about 4.5 ppm; and (2) molybdate based formation of electroactive phosphomolybdate complexes, (Jońca et al., 2011), (Li et al., 2016), enabling quantification with limits of detection of 2 ppm using CV and 0.2 ppm using DPV. This microfluidic platform enable rapid analysis, low reagent use, and operation in complex matrices, making them suitable for on-site environmental monitoring.