Nitrogen Specific Ion Electrodes for Soil, Plant, and Water Analysis

Abstract

Abstract The nitrate specific ion electrode and the ammonia and nitrogen dioxide gas-sensing combination electrodes offer simple methods of analyses of plants, soils, and water. The nitrate electrode measures activity of the nitrate ion in solution and is susceptible to interfering ions, particularly Cl. Considerable discrepancies exist in the literature concerning nitrate extracting solutions and buffering solutions used to eliminate interferences with the nitrate electrode. An evaluation of ionic strength adjusters, used to alleviate fluctuating ionic background interferences, indicates (NH4)2SO4 produces consistent results without adversely affecting life of the nitrate electrode. Ammonia electrode determination of total nitrogen in soil, plant, and water samples is a rapid method that eliminates the time-consuming distillation-titration step. The nitrogen dioxide electrode is relatively new and little information is available concerning methodology and its potential problems.