Simultaneous detection of ammonia and nitrate using a modified electrode with two regions

Simultaneous detection of ammonia and nitrate has significance in the application areas of environment and industry. Conventional methods include additional steps to separate ammonia and nitrate before detection. A more convenient method is required to detect ammonia and nitrate directly in their mixture. In this work, a modified electrode with electrodeposited Pt region and Ag region was prepared to simultaneously detect ammonia and nitrate for the first time. The Pt region and Ag region were designed to selectively determine ammonia and nitrate, respectively, free of interference with each other. A nonlinear correlation between ammonia oxidation current and ammonia bulk concentration and a linear correlation between nitrate reduction current and nitrate bulk concentration were found. The simultaneous detection limits of ammonia and nitrate were 3.946 μM and 0.134 mM, respectively. The modified electrode showed good long-term stability for the simultaneous detection of ammonia and nitrate with relative standard deviations of 7.10% and 3.93%, respectively. The modified electrode exhibited good anti-interference ability toward Na⁺, K⁺, Cl⁻ and SO₄ ²⁻. This work demonstrated a simple and fast approach for detecting two components in solution.