Optical sensor for ammonia based on the inner filter effect of fluorescence

Area of Science:

• Analytical Chemistry
• Materials Science
• Environmental Monitoring

Background:

• Ammonia gas detection in aqueous solutions is crucial for environmental and industrial applications.
• Existing methods for ammonia monitoring can be complex or lack sensitivity.
• Development of novel sensor materials is needed for efficient ammonia sensing.

Purpose of the Study:

• To present a new indicator-immobilization technique for ammonia gas sensor development.
• To create a sensor material for monitoring ammonia in aqueous solutions.
• To characterize the performance of the developed ammonia sensor.

Main Methods:

• Developed a sensor material by homogeneously dissolving a lipophilized pH indicator in silicone rubber.
• Utilized the change in absorbance intensity of the indicator upon exposure to ammonia.
• Employed bromophenol blue as the pH indicator, monitoring its deprotonation and subsequent absorbance increase.

Main Results:

• The sensor demonstrated a response over a wide concentration range of 17 μg/L to 17 mg/L.
• Achieved a low detection limit of 12 μg/L for ammonia.
• The sensor material showed sensitivity to ammonia-induced changes in indicator absorbance.

Conclusions:

• The indicator-immobilization technique provides a viable method for developing ammonia gas sensors.
• The developed sensor material is effective for monitoring ammonia in aqueous solutions.
• The sensor exhibits promising sensitivity and a low detection limit for ammonia.