Simple, robust, and low-cost nitrate- and ammonium-selective electrodes were made using substrate prepared from household materials. We explored phosphonium-based ILs and poly (methyl methacrylate)/poly(decyl methacrylate)(MMA-DMA) copolymer as matrix materials alternative to classical PVC-based membranes. IL-based membranes showed suitability only for nitrate-selective electrode exhibiting linear concentration range between 5.0 × 10⁻⁶ and 2.5 × 10⁻³ M with a detection limit of 5.5 × 10⁻⁷ M. On the other hand, MMA-DMA—based membranes showed suitability for both ammonium- and nitrate-selective electrodes, and were successfully applied to detect NO₃⁻ and NH₄⁺ in water and soil samples. The proposed ISEs exhibited near-Nernstian potentiometric responses to NO₃⁻ and NH₄⁺ with the linear range concentration between 5.0 × 10⁻⁵ and 5.0 × 10⁻² M (LOD = 11.3 µM) and 5.0 × 10⁻⁶ and 1.0 × 10⁻³ M (LOD = 1.2 µM), respectively. The power of ISEs to detect NO₃⁻ and NH₄⁺ in water and soils was tested by comparison with traditional, portable colorimetric techniques. Procedures required for analysis by each technique from the perspective of a non-trained person (e.g., farmer) and the convenience of the use on the field are compared and contrasted.

An overview is given dealing with application of ion-selective electrodes (ISEs) in environmental analysis. ISEs are placed into the context of the trend of development of sensors for extensive and frequent monitoring. Discussed are the issues such as sensing platforms and their mass-production, improvement of precision, diagnostic of sensor?s functionality, and development of reference electrodes and several examples of real-life application of ISEs in environmental analysis are given. The main emphasis of this article is directed towards summarizing recent of authors? results during the past several years.

In this paper, we demonstrate the suitability, sensitivity, and precision of low‐cost and easy‐to‐use ion‐selective electrodes (ISEs) for concurrent detection of NH₄⁺ and NO₃^‐ in soil and water by technical and non‐technical end‐users to enable efficient soil and water management exposed to chronic reactive nitrogen loading. We developed a simplified methodology for sample preparation followed by the demonstration of an analytical methodology resulting in improvements of sensitivity and precision of ISEs. Herein, we compared and contrasted ISEs with traditional laboratory‐based technique such as Flow Injection Analysis (FIA) and portable colorimetric assay followed by comparisons of linear regression and Bayesian nonlinear calibration approaches applied on both direct potentiometry and standard addition modes of analysis in terms of in‐field applications and improvement of sensitivity and precision. The ISEs were validated for sensing on a range of ambient soil and water samples representing a range of NH₄⁺ and NO₃^‐ concentrations from pristine to excessive saturation conditions. Herein developed methodology showed excellent agreement with lab‐based and portable analytical techniques while demonstrating improvements in precision and sensitivity analysis illustrated by a decrease in confidence intervals by 50‐60%. We also demonstrated the utilization of the entire ISE response curve thus removing the biases originating from linear approximation which is often currently employed. Therefore, we show that ISEs are robust yet low cost and an easy to use technology that can enable high‐frequency measurement of mineral N and help to improve our understanding of N transformation processes as influenced by soil management, fertilization, land use, and climate change.