Rotating electrode potentiometry: lowering the detection limits of nonequilibrium polyion-sensitive membrane...

Area of Science:

• Electrochemistry
• Analytical Chemistry
• Materials Science

Background:

• Polyion-sensitive membrane electrodes (PSEs) are crucial for detecting charged polymers.
• Conventional PSEs face limitations in detection sensitivity.
• Improving detection limits is essential for accurate polyion analysis.

Purpose of the Study:

• To evaluate a rotating electrode configuration for enhancing PSE detection limits.
• To assess the performance of polycation and polyanion PSEs under rotation.
• To explore the application of rotating PSEs in titration analysis.

Main Methods:

• Preparation of planar potentiometric polycation and polyanion PSEs using specific ionophores in PVC or polyurethane membranes.
• Mounting PSE membranes on a rotating disk electrode apparatus.
• Assessing EMF responses at 5000 rpm and comparing with static (stirred) conditions.
• Titration of heparin with protamine using a rotating polycation sensor.

Main Results:

• Rotation at 5000 rpm improved detection limits by at least one order of magnitude for heparin and protamine.
• A linear relationship was observed between omega(-1/2) and C1/2.
• The rotating polycation sensor enhanced analytical resolution and precision for low-concentration heparin titration.

Conclusions:

• A rotating electrode configuration effectively lowers detection limits for PSEs.
• This method offers a significant improvement over conventional stirred methods for polyion detection.
• Rotating PSEs show promise for precise analytical measurements and endpoint detection.