Analytical Sciences


Abstract − Analytical Sciences, 34(12), 1373 (2018).

Construction of Nitrate-selective Electrodes and Monitoring of Nitrates in Hydroponic Solutions
Yuko FUKAO, Yuki KITAZUMI, Kenji KANO, and Osamu SHIRAI
Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo, Kyoto 606-8502, Japan
A liquid-membrane type nitrate-selective electrode was constructed, in which the responding membrane contained polyvinylchloride, o-nitrophenyloctylether and tetraheptylammonium nitrate. The NO3-selective electrode displayed a linear response to the concentration of NO3 with a Nernstian slope of −53.3 ± 1.0 mV decade−1, in the 10−5 – 10−1 mol dm−3 (M) NO3 concentration range. The NO3 detection limit was about 10−6 M. The electrochemical response of this electrode was stable for more than 30 days. Measurements performed using the NO3-sensor indicated that in the presence of green plants, the concentration of NO3 in a hydroponic solution decreased from 0.20 to 0.05 mM over a three-day period.