Ion-selective electrode (ISE) is an important instrument for analyzing various electrolytes like Sodium, Potassium, Chloride, and Lithium in the pathology laboratory.

ISE is used in many departments of the medical field.

Principle of the ion-selective electrode (ISE)

It produces potential that is proportional to the concentration of the tested analyte.

Making measurements with ISE is a form of potentiometry. The most common ion-selective electrode is the Ph electrode. It contains This glass membrane responding to the hydrogen ions concentration in a solution.

Ion-selective electrode operational procedure

Following are the steps inion the selective electrode procedure.

  • First rinse the Ion Selective Electrode and place it for dry.
  • Now rinse the REFERENCE electrode.
    • NOTE: Gently bolt the tip of both electrodes.
  • Rinse and dry the stir bar.
  • Rinse the sample baker at least three times.
  • Prepare standard samples and a test sample.
  • Sequence measure the standard samples and test samples.

What are the types of ion-selective electrodes?

There are 4 types of ions measuring electrodes.

  • Glass ion-selective electrode
  • Liquid base electrode
  • Solid base electrode
  • Compound electrode

Each electrolyte ion has its own electrode. There are four kinds of electrodes.

  • Sodium (Na)
  • Potassium (K)
  • Lithium (Li)
  • Chloride (Cl)
  • Calcium (Ca)
  • Bicarbonate

Electrolytes are incorporated with arterial blood gas (ABGs) machines. It sucks an undiluted sample and the result is directly displayed on the screen. Such instruments are self-calibrated.

NOTE: Electrodes have to be kept in a buffer all the time, as drying will destroy the delicate measuring membrane and render the ISE useless.

What is the electrolytes reference range table in the (Sodium, Potassium, and Chloride) serum?

Sodium136 – 145 mmol/l
Potassium96- 106 mmol/l
Chloride3.5 -4.5 mmol/l
Electrolytes normal range table

What is the most commonly used ion-selective electrode (ISEe) in the medical field?

PH meter is the most commonly used ISE in the medical field. Other electrodes like sodium, potassium, and chloride electrodes are also available.

What are the components of ion-selective electrodes?

ISE consist of four components.
1. Ion-selective membrane
2. Internal reference electrode
3. External Reference electrode
4. Voltmeter

What is the effect of the hemolysis sample on electrolytes?

Sodium and chloride ions are present in the plasma, but potassium came out from red blood cells. when hemolysis occurs, more potassium came out from RBC. Hence potassium increased. Hemolysis did not affect the sodium and chloride ions.

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