Point-of-Care-Testing NO₃-N Detection Technology with Selected Transition-Metal-Based Colorimetric Sensor Arrays.

Area of Science:

• Environmental Chemistry
• Sensor Technology
• Analytical Chemistry

Background:

• Nitrate-nitrogen (NO₃-N) is a pervasive water contaminant, impacting ecosystems and human health.
• Conventional NO₃-N detection methods are time-consuming due to necessary sample pretreatment for complex matrices.
• Effective on-site monitoring of NO₃-N is crucial for water quality management in marine aquaculture and drinking water.

Purpose of the Study:

• To develop a novel, rapid, on-site sensor for detecting nitrate-nitrogen (NO₃-N) concentrations.
• To create a sensor system that eliminates the need for sample pretreatment in complex water samples.
• To establish a foundation for developing selective array sensors for various analytes.

Main Methods:

• Transition-metal-based sensors were formulated using various metals (Mn, V, Fe, Co, Cr, Cu, Ni) and tested with NO₃-N standard solutions (1-100 ppm).
• Color change kinetics of sensors were analyzed to identify those with linear responses to increasing NO₃-N concentrations.
• An array sensor was constructed using selected sensors, and its performance was validated against hierarchical cluster analysis (HCA) and compositional analysis.

Main Results:

• Selected transition-metal sensors demonstrated linearly increasing color velocity with rising NO₃-N concentrations.
• The developed array sensor successfully detected NO₃-N in complex matrices, validated by HCA.
• Generated color data patterns show potential for creating selective sensors for specific substance detection beyond just NO₃-N.

Conclusions:

• A novel transition-metal-based array sensor enables on-site, rapid, and accurate NO₃-N detection without pretreatment.
• The sensor system overcomes limitations of traditional methods, offering a significant advancement in water quality monitoring.
• The developed platform facilitates the creation of advanced array sensors for detecting diverse analytes in complex environmental samples.