Determination of nitrate in drinking water by ion-selective electrode.

Abstract

Nitrate concentration in drinking water was directly determined by employing an ion selective liquid membrane electrode (ISE). This was constructed with poly(vynil chloride) as matrix on a solid conducting support. Tetra-decyl ammonium nitrate (TDAN) was used as ionophore and dibutyl phthalate as plasticizer and solvent-mediator. The constructed ISE showed Nernstian slope with value of-61,2+-0,2 mV/dec-1, practical detection limit (PDL) of9,59 · 10-6 mol/dm3, lower limit of linear response (LLLR) of 2,82 · 10-5 mol/dm3,pH range of 5,0-11,5 life-time of >6 months without any divergence and with stable response of 15 seconds. Determination of nitrate ion concentration in drinking water was preformed by direct potentiometric method. Reliability of the electrode was evaluated by measuring the nitrate concentration by ion chromatography as a comparative method. The results showed good agreement between the values obtained by both methods, indicating the applicability of the proposed electrode for accurate determination of nitrate concentration in drinking water, where the measured values were less than 10 mg/L.