Polymer–multiwall carbon nantubes composites for durable all solid-contact H2PO4−-selective electrodes

Durable all solid-contact H2PO4−-selective electrodes were developed using a facile one-step drop casting method, which doped the ion-sensing components, uranyl salophene and multiwall carbon nanotubes (MWCNTs) composites directly on a solid substrate. The optimized hybrid film-based solid-state electrodes demonstrated the improved selectivity and lower detection limit for H2PO4− than the reported Ionophore I-based CHEMFETs. Due to the hydrophobicity of MWCNTs incorporated membrane, our polymer–MWCNTs composite membrane presented remarkable long-term potential stability in comparison with traditional ion-sensing membrane without MWCNTs. The sensitivity of polymer–MWCNTs membranes for H2PO4− was near to Nernstian response after the conditioning in flowing cell for 115h exhibiting the extended lifetime. The application of the new sensor was verified in imitated eutrophicated water samples, and the result was comparable to the value using classic spectrometry. This robust, reusable and maintenance-free ion sensor will be suitable for on-line continuous H2PO4− determination in environmental and clinical application.