Screen-printed electrode modified with the carbon black nanoparticles as a cost-effective and sensitive sensor for phosphate detection

The final aim of this work is the realization of an automatic system based on amperometric measurements able to detect the phosphate in absence of the operator, thus in remote mode control, using automatic valves leaded by a software. The SPEs (screen-printed electrodes) thank to their small size and long term stability, can be easily embedded in a flow system for continuous in situ analysis. Gold nanoparticles (AuNPs), carbon black (CB) and both of them have been used to obtain “composite” (CB/AuNPs) for modifying the SPEs. The different types of sensor (SPE-AuNPs, SPE-CB and SPE-CB/AuNPs), obtained by drop casting technique, were challenged towards phosphate in order to investigate the electrochemical performances. The optimization of the operative parameters for the phosphate detection has been carried out first via batch measurements and in the second step, the flow system has been assembled and re-optimized. The amperometric method developed in this work is able to detect phosphate in a linear range from 20 to 80 µM with detection limit equal to 6 µM (calculated as 3σ/ slope). Moreover, the system was challenged toward tap, river and lake water samples and compared to the colorimetric reference method; a good concordance of the results confirmed that the method is able to detect phosphate also in a complex matrix such as River water.