A highly selective nitrate electrode based on a tetramethyl cyclotetra-decanato-nickel(II) complex

A new nitrate-selective coated-wire electrode based on the complex (6,8,15,17-tetramethyl-7H,16H-5,9,14,18-tetraazidobenzo[b,i]-cyclotetra-decanato-(2-)-K4-N,N′,N″,N‴) Ni(II) as the membrane carrier was developed. The electrode exhibits a good Nernstian slope of −57.8 ± 1.0 mV/decade and a linear range of 1.0 × 10−5–1.0 M for nitrate. The limit of detection is 5.0 × 10−6 M. It has a fast response time of 15 s and can be used for more than four months. The selective coefficients were determined by the fixed interference method (FIM) and could be used in the 2.2–9.4 pH range. The electrode was employed as an indicator electrode for direct determination of nitrate in fresh water.