Ion-selective potentiometry in clinical chemistry. A review

Area of Science:

• Clinical chemistry and analytical techniques.
• Biomedical sensor technology.

Background:

• Ion-selective potentiometry (ISP) is increasingly adopted in clinical medicine for electrolyte determination in body fluids.
• ISP has largely replaced older methods like flame photometry and atomic absorption spectrophotometry for key electrolytes (K+, Na+, Ca2+, Cl-).

Purpose of the Study:

• To highlight the significance and applications of ion-selective potentiometry in clinical diagnostics.
• To discuss the various types of ion-selective sensors and their specific uses.
• To address critical factors for achieving accurate results with ISP.

Main Methods:

• Overview of six types of ion-selective sensors: glass membrane, solid phase, fluid membrane, carrier, gas-sensitive, and enzyme electrodes.
• Discussion of direct versus indirect potentiometry and activity-to-concentration extrapolation challenges.
• Emphasis on essential pre-measurement steps: calibration, sample preparation, and condition adjustment.

Main Results:

• ISP is indispensable for rapid clinical diagnostics, covering essential cations (H+, K+, Na+, Ca2+, Mg2+, NH3+) and anions (F-, I-, Br-, Cl-, HCO3-).
• Automated devices have streamlined routine analyses, enhancing efficiency.
• Enzyme electrodes are crucial for in vivo monitoring, including continuous blood glucose monitoring.

Conclusions:

• Ion-selective potentiometry is a significant advancement in clinical chemistry, offering rapid and indispensable diagnostic capabilities.
• Addressing disturbing factors through careful calibration, sample handling, and quality control is crucial for optimal method performance.
• Consequent internal and external quality control ensures the high quality of vital parameter measurements.