A nitrate-selective electrode based on a tris(2-aminoethyl)amine triamide derivative receptor

A tris(2-aminoethyl)amino triamide derivative anion receptor has been tested as electroactive material for the development of anion-selective electrodes. The receptor was incorporated in plasticized poly(vinyl chloride) membranes of different compositions. The membrane that provided the best response and selectivity towards nitrate was selected to develop a new nitrate-selective electrode. The electrode exhibited a Nernstian response over the nitrate concentration range of 1 × 10^-5 to 1 × 10^-1 mol l^-1 with a slope of -54.7 mV/decade of concentration, a detection limit of 2.3 × 10^-6 mol l^-1 nitrate, a wide working pH range (2–12) and a fast response time. It showed good selectivity for nitrate relative to many common anions and better selectivity relative to thiocyanate, perchlorate and nitrite than previous nitrateselective electrodes. Quantum chemical calculations made to study the interaction between the receptor and the different anions assayed are used to explain these improvements. The proposed electrode was applied to the determination of nitrate in drinking waters.