Detection of Propionic Acids Trapped in Thin Zeolite Layer Using Thermal Desorption Analysis

Area of Science:

• Analytical Chemistry
• Sensor Technology
• Biochemical Monitoring

Background:

• Volatile organic compounds (VOCs) are crucial biomarkers for various biochemical processes in biological systems.
• Existing methods for VOC analysis can be limited in sensitivity and selectivity, especially for low-concentration samples.
• There is a need for advanced analytical techniques to accurately monitor biochemical processes using VOC fingerprints.

Purpose of the Study:

• To develop a novel sensor for the selective analysis of volatile organic compounds (VOCs).
• To utilize a photoionization detector (PID) coupled with a zeolite layer for enhanced VOC detection.
• To evaluate the sensor's performance in identifying and quantifying VOCs based on their thermal desorption profiles.

Main Methods:

• Development of a sensor system integrating a zeolite layer with a photoionization detector (PID).
• Analysis of VOCs via thermal desorption in a stainless-steel chamber, monitoring emissive profiles.
• Application of a double exponential mathematical model to describe evaporation and diffusion processes during desorption.
• Investigation of zeolite selectivity for propionic acid versus succinic acid and optimization of adsorption time (5-60 min) at 100 °C.

Main Results:

• The zeolite layer demonstrated selectivity for propionic acid over succinic acid, with linear behavior at low concentrations.
• Optimal adsorption time for propionic acid was determined to be 15 minutes, with maximum concentration detected at this point.
• Evaporation rate increased with desorption temperature, while diffusion rate remained relatively constant.
• Larger analysis chamber volumes led to an increased diffusion ratio.

Conclusions:

• The developed zeolite-PID sensor offers a selective and sensitive alternative for VOC analysis, effective even at low concentrations.
• The sensor's ability to analyze thermal desorption profiles provides valuable insights into biochemical processes.
• The integration of zeolite and PID enhances selectivity, paving the way for portable VOC detection devices in diverse applications.