Effects of type of nanosized carbon black on the performance of an all-solid-state potentiometric electrode for nitrate

The potentiometric properties of all-solid-state nitrate-selective electrodes based on plasticized PVC and containing different types of nanosized carbon black were investigated. The use of a carbon black interlayer is shown to significantly improve the potentiometric response. The electrodes display a close-to-Nernstian slope in the range from 10(-1) to 10(-6) M, highly stable potentials and low membrane resistance. However, different analytical features were found depending on the type of carbon black used. The best long-term potential stability was observed for the electrode with Printex XE2-B carbon black that has a relatively high BET surface area (1000 m(2) center dot g(-1)) and an average particle size of 30 nm. Nevertheless, the electrodes with the Vulcan XC-72 (BET surface: 240 m(2) center dot g(-1); average size: 55 nm) showed the most repeatable and reproducible standard potential. The lowest detection limit for nitrate (2.5 center dot 10(-7) M) is observed for an electrode containing Vulcan XC-72.