SO₂ Gas Sensing by Nanometer-Thick Soap Films Using Conductometry and Fluorimetry.

Area of Science:

• Materials Science
• Analytical Chemistry
• Environmental Science

Background:

• Sulfur dioxide (SO2) is a harmful air pollutant and a key factor in food and beverage quality.
• Developing sensitive and cost-effective SO2 sensors is crucial for environmental monitoring and quality control.

Purpose of the Study:

• To demonstrate the use of common black films (CBF) for conductometric and fluorometric sensing of SO2 gas.
• To evaluate the limit of detection (LOD) and linear range of these sensing methods.
• To assess the applicability of CBF-based sensors for real-world samples.

Main Methods:

• Nanometer-thick common black films (CBF) with large specific surface area were utilized.
• Conductometric sensing involved SO2 oxidation by H2O2 in CBF, increasing conductance.
• Fluorometric sensing involved the reaction of SO2 with Rhodamine B hydrazide in CBF to produce fluorescence.

Main Results:

• Conductometric method: LOD of 70 ppb, linear up to 1 ppm SO2, and nonlinear correlation up to 25 ppm.
• Fluorometric method: LOD of 100 ppb, linear for 0.1-25 ppm SO2.
• Successful sensing of SO2 released from wine and beer samples was achieved.

Conclusions:

• Common black films (CBF) are effective platforms for both conductometric and fluorometric SO2 gas sensing.
• The developed methods offer sensitive detection with practical LODs for environmental and food applications.
• CBF-based SO2 sensors demonstrate potential for real-time monitoring and quality assessment.