Electropolymerized poly(methylene blue)-modified graphite electrode for phosphate detection

A graphite electrode modified with an electropolymerized poly(methylene blue) (PMB) film was prepared and evaluated as an electroanalytical platform for phosphate detection in aqu­eous media. The PMB layer was deposited on graphite by potentiodynamic electro-poly­me­rization via cyclic voltammetry and characterized by cyclic voltammetry (CV), electro­che­mical impedance spectroscopy, scanning electron microscopy and Fourier-transform infra­red spec­tro­scopy. Compared to the bare graphite electrode, the modified surface exhibited impro­ved interfacial electrochemical properties and an increased electroactive surface area. The elec­troanalytical response toward phosphate was investigated using differ­en­tial pulse voltam­metry (DPV), chronoamperometry and CV, revealing a linear response in the concen­tra­tion range from 50 to 475 mM, as determined from DPV and chronoampero­metric measu­re­ments. The modified electrode showed good reproducibility, low interference from common inor­ga­nic ions, and satisfactory performance in real water samples, with recovery values close to 100 %. These results demonstrate that the PMB-modified graphite electrode constitutes a sim­ple and reliable electroanalytical approach for phosphate determination in environmental samples.