Improved Nitrate Sensing Using Solid Contact Ion Selective Electrodes Based on TTF and Its Radical Salt

The possibility of improving the selectivity of solid-state nitrate-selective electrodes by the application of the tetrathiafulvalene (TTF) or its nitrate salt (TTF(NO 3 )) as an intermediate layer between an electrical conductor and a polymeric membrane is demonstrated. The analytical performance of electrodes was investigated during potentiometric measurements. Fabricated sensors displayed a Nernstian slope (−58.85 mV/decade in the range from 10 −5.0 to 10 −1 M and −59.36 mV/decade in the range from 10 −6.0 to 10 −1 M for TTF− and TTF(NO 3 )−modified electrodes respectively), repeatable and reproducible standard potential and detection limit of 2.5 μM (0.16 mgL −1 ) and 0.63 μM (0.039 mgL −1 ) for TTF− and TTF(NO 3 )−based electrodes, respectively. The selectivity was considerably improved compared to a coated disc electrode or electrodes with intermediate layer based on carbon nanomaterials. Electrical parameters of the proposed sensors were tested by carried out current-reversal chronopotentiometry. In the case of electrodes with the use of TTF or TTF(NO 3 ) the potential drift decreases to 167 μVs −1 or 16.6 μVs −1 and the capacitance is 5.99 μF or 60.3 μF. The proposed sensors were successfully applied in analyzing nitrate concentration in water samples.