Protein effect on the antimony microelectrode in application to biological fluid

Area of Science:

• Analytical Chemistry
• Biomedical Engineering
• Electrochemistry

Background:

• Accurate pH measurement is crucial for biological fluid analysis.
• Antimony (Sb) microelectrodes are commonly used for pH determination.
• Protein interference can affect electrode performance and measurement accuracy.

Purpose of the Study:

• To investigate the influence of protein on Sb-microelectrode performance.
• To quantify the pH shift caused by protein in biological samples.
• To develop methods for correcting protein-induced errors in pH measurements.

Main Methods:

• Tested bovine serum albumin (BSA) and plasma protein with Sb-microelectrodes.
• Measured electromotive force and slope constant deviations.
• Developed a cubic function to predict pH shifts based on protein concentration.
• Utilized Tris standard solution for calibration and applied corrections for temperature, ionic strength, and Po2.

Main Results:

• BSA caused a significant alkaline pH shift (0.1-0.7) by binding to electrode components.
• The pH shift could be empirically predicted within +/- 0.03 pH units using a cubic function of protein concentration.
• Calibration with Tris buffer and applied corrections reduced alkaline shifts to <0.08 pH units for plasma and <0.04 pH units for whole blood.

Conclusions:

• Protein concentration is a critical factor affecting Sb-microelectrode accuracy in biological fluids.
• Empirical prediction and specific calibration/correction strategies can significantly mitigate protein-induced pH measurement errors.
• Optimized methods enable more reliable Sb-microelectrode pH measurements in protein-rich biological samples.