Exploiting the pH-Cross Sensitivity of Ion-Selective Optodes to Broaden Their Response Range
Fabian Steininger1, Johan Palmfeldt2, Klaus Koren1
1Aarhus University Centre for Water Technology, Department of Biology, Section for Microbiology, Aarhus University, Ny Munkegade 114-1540, Aarhus C, 8000, Denmark.
ACS Sensors
|August 22, 2024
Summary
pH cross-sensitivity in ion-selective optodes can be leveraged to expand their measuring range. Immobilized pH gradients enhance optode performance, increasing the effective measurement range for ions like sodium.
Area of Science:
- Chemical Sensing
- Analytical Chemistry
- Materials Science
Background:
- Chromoionophore-based ion-selective optodes (ISOs) traditionally face limitations due to pH cross-sensitivity.
- This pH dependency is often viewed as a drawback in sensor applications.
Discussion:
- This study reframes pH cross-sensitivity as an advantageous characteristic for ISOs.
- Integrating ISOs with immobilized pH gradient (IPG) gels creates a stable pH gradient across the optode.
- This gradient effectively shifts the response range of the ISOs, enhancing their utility.
Key Insights:
- The measuring range of sodium-selective optodes was extended by up to 2.5 log units using IPG gels.
- The enhancement in measuring range is directly proportional to the magnitude of the pH gradient.
- This technique is adaptable to various ion-selective chromoionophore-based optodes.
Outlook:
- This approach offers a pathway to develop more versatile and sensitive optodes for a wider array of analytes.
- Future research can explore greater enhancements with more pronounced pH gradients.
- The findings have broad implications for advancing chemical sensing technologies.
