ACS Publications Announces Low-Cost, Open-Source In Situ Near-Real-Time Sensor for Nitrate & Ammonia in Environmental Waters: Achieves R2 of 0.96 with Over 400 Stable Responses

July 5, 2026

ACS Publications USA

Overview

This research developed a low-cost, open-source, in situ, near-real-time sensor for detecting nitrate and ammonia in environmental waters. The colorimetric sensor achieved near-perfect accuracy with an R2 value of 0.96 for both nitrate and ammonia, demonstrating reliable performance even in environmental samples. A stable ammonia response was confirmed over 400+ laboratory and field measurement cycles, highlighting its potential as a portable environmental monitoring system. This innovation opens new avenues for monitoring and managing water pollution.

In Depth

Key Findings

New research published in ACS Publications details the development of a low-cost, open-source, in situ, near-real-time sensor for detecting nitrate and ammonia in environmental waters. This colorimetric sensor achieved near-perfect accuracy, with an R2 value of 0.96 for both nitrate and ammonia, and demonstrated highly reliable performance in real-world environmental samples. Notably, the sensor maintained a stable ammonia response over more than 400 laboratory and field measurement cycles, unequivocally demonstrating its robustness and long-term utility. This groundbreaking technology is poised to establish new benchmarks for monitoring and managing water pollution.

Technical / Clinical Details

The developed sensor utilizes a colorimetric method, optically detecting color changes that occur when target ions (nitrate and ammonia) react with specific reagents. The sensor’s design is straightforward, composed of 3D-printable components and commercially available, inexpensive electronic parts, which significantly keeps the overall manufacturing cost low. For nitrate detection, a diazotization-coupling reaction employing cadmium reduction is used, while Nessler’s reagent is employed for ammonia detection. The sensor integrates microfluidic channels and an optical detector to automate sampling, reagent injection, mixing, and colorimetric analysis. The high coefficient of determination (R2 = 0.96) indicates an extremely strong correlation between the sensor’s measurements and reference laboratory analytical methods (e.g., ion chromatography, ammonia electrode methods). The confirmation of over 400 stable ammonia responses suggests the sensor’s resistance to reagent degradation and reliability in repeated use, confirming its suitability for continuous monitoring with low maintenance frequency.

Background & Context

Nitrate and ammonia in water are major pollutants stemming from agricultural runoff, industrial wastewater, and untreated urban sewage. Excessive concentrations can lead to eutrophication, severely impacting ecosystems, and nitrates in drinking water can pose adverse health effects to humans. Monitoring these pollutants is essential for environmental protection and public health, yet conventional laboratory-based analyses are often time-consuming, costly, and hinder real-time data acquisition. This low-cost, open-source, in situ sensor addresses these challenges, empowering local governments, environmental protection agencies, and researchers to monitor water quality more efficiently and frequently. Its open-source nature offers a significant advantage, allowing researchers and developers worldwide to improve the design and customize it for specific regional needs.

Strategic Significance & Outlook

This sensor technology holds immense potential to transform the future of environmental monitoring. In the future, the platform could be expanded to simultaneously detect other water quality pollutants, such as phosphates, heavy metals, and specific pesticides. Furthermore, integration with IoT (Internet of Things) technology could enable the creation of sensor networks, aggregating and analyzing water quality data from extensive water bodies (rivers, lakes, groundwater) in the cloud. This will facilitate the identification of pollution sources, tracing of pollution pathways, and prompt implementation of effective mitigation measures. This low-cost, high-reliability sensor is particularly expected to enhance water resource management capabilities in developing countries, significantly contributing to improved access to safe drinking water and the protection of aquatic ecosystems globally.

Source: https://pubs.acs.org/doi/10.1021/acsestwater.6c00349

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