Ionic-liquid doped polymeric composite as passive colorimetric sensor for meat freshness as a use case

Area of Science:

• Materials Science
• Chemical Sensors
• Analytical Chemistry

Background:

• Composite membranes incorporating ionic liquids (ILs) and nanoparticles offer tunable properties for sensing applications.
• Polydimethylsiloxane (PDMS) and tetraethyl orthosilicate (TEOS) influence sol-gel porosity, impacting sensor performance.
• 1,2-naphthoquinone-4-sulfonic acid sodium salt (NQS) provides selectivity for target analytes.

Purpose of the Study:

• To develop and evaluate a novel composite membrane sensor for ammonia detection.
• To investigate the influence of ionic liquids and matrix components on sensor performance.
• To demonstrate the sensor's application in monitoring meat freshness.

Main Methods:

• Fabrication of a composite membrane with NQS, IL (OMIM PF6), PDMS, TEOS, and SiO2 nanoparticles.
• Ammonia sensing using diffuse reflectance measurements and smartphone-captured RGB images.
• Testing sensor performance under varying sampling times, temperatures, and volumes.
• Quantification of ammonia in meat packaging environments.

Main Results:

• The sensor demonstrated high sensitivity to ammonia, with calibration slopes significantly higher (48-91%) than sensors without ILs.
• Performance was adaptable to different sampling conditions (time, temperature, volume).
• Selective detection of ammonia in the presence of other volatile compounds (e.g., sulfides) was achieved.
• Accurate quantification of ammonia in meat packaging over 10 days at 4°C.

Conclusions:

• The developed composite membrane sensor is a promising, cost-effective tool for in situ monitoring of ammonia.
• The sensor enables real-time assessment of meat freshness by detecting ammonia levels.
• The integration of ILs and nanoparticles enhances sensor selectivity and sensitivity.