Distance and Color Change Based Hydrogel Sensor for Visual Quantitative Determination of Buffer Concentrations

Area of Science:

• Analytical Chemistry
• Materials Science
• Biotechnology

Background:

• Accurate determination of pH buffer capacity is crucial for various scientific and industrial applications.
• Conventional methods like acid-base titrations can be time-consuming and may perturb sensitive samples.

Purpose of the Study:

• To develop and validate an innovative optical sensor platform for determining pH buffer capacity.
• To demonstrate the sensor's applicability in real-world scenarios, such as seawater alkalinity analysis.

Main Methods:

• Utilized FITC-dextran loaded hydrogels as pH-sensitive materials.
• Analyzed optical signals (distance and color change) from the hydrogels to quantify buffer capacity.
• Validated the methodology across five buffer systems and compared results with a theoretical model.

Main Results:

• Achieved wide linearity (0.1 to 100 mM) and good batch-to-batch reproducibility.
• Demonstrated high versatility and resistance to background ionic strength variations.
• Successfully applied the sensor for carbonate alkalinity determination in seawater, showing excellent performance.

Conclusions:

• The FITC-dextran hydrogel platform provides a novel, low-perturbation method for pH buffer capacity determination.
• The sensor exhibits significant potential for diverse analytical applications, offering advantages over conventional titration techniques.