A miniaturized fiber-optic colorimetric sensor for nitrite determination by coupling with a microfluidic capillary...

Area of Science:

• Analytical Chemistry
• Environmental Science
• Sensor Technology

Background:

• Nitrite is a hazardous pollutant in water.
• Accurate and portable nitrite detection methods are needed for environmental monitoring.

Purpose of the Study:

• To develop a novel microfluidic-capillary-waveguide-coupled fiber-optic sensor for nitrite determination.
• To provide a low-cost, portable, and environmentally friendly method for in situ and online nitrite measurement.

Main Methods:

• Colorimetric determination based on the Griess-Ilosvay reaction.
• Modular sensor design using LED, silica fiber, and capillary waveguide.
• Light interaction with azo dye generated from nitrite and Griess reagents.

Main Results:

• Wide linear range for nitrite (0.02–1.8 mg L⁻¹).
• Low detection limit of 7 μg L⁻¹ with high precision (RSD 0.37%).
• Short response time (6.24 s) and low reagent consumption (200 μL).

Conclusions:

• The developed sensor offers a cost-effective and portable solution for nitrite monitoring.
• The sensor demonstrates excellent selectivity and potential for practical application in water quality analysis.
• Results align with conventional spectrophotometry and ion chromatography, validating the sensor's performance.