Screen-printed electrode modified with carbon black nanoparticles for phosphate detection by measuring the electroactive phosphomolybdate complex

We report a sensor for phosphate detection based on screen-printed electrodes modified with carbon black nanoparticles. The phosphate was measured in amperometric mode via electrochemical reduction of molybdophosphate complex. Carbon black nanoparticles demonstrated the ability to quantify the molybdophosphate complex at a low applied potential. Some analytical parameters as the working solution (sulphuric acid 0.1 M), applied potential (0.125 V vs Ag/AgCl), and molybdate concentration (1 mM) were optimised. Using these conditions, a linear range of 0.5 - 100 µM was observed with a detection limit of 0.1 µM, calculated as three times the standard deviation of the blank divided by the calibration curve slope. The system was challenged in drinking, river, and aquarium water samples yielding satisfactory recovery values in accordance with a spectrophotometric reference method which demonstrated the suitability of the screen-printed electrode modified with carbon black nanoparticles coupled with the use of molybdate to detect phosphate in water samples.