Discover the principle and working of pH probe in this easy-to-understand guide. Learn how pH measurement works.
What is pH probe?
It also known as pH sensors or electrodes, are key tools to measure the acidity or alkalinity of a solution. pH measurement is a fundamental aspect of many industries, including pharmaceuticals, food production, and environmental monitoring.
What is pH?
pH is a measure of the hydrogen ion concentration in a solution and indicates its acidity or alkalinity. The pH scale ranges from 0 to 14, with 7 being neutral. Values below 7 represent acidity, while values above 7 indicate alkalinity. pH is a logarithmic scale, meaning that each unit represents a tenfold difference in acidity or alkalinity.
pH Probe Principle
pH probe principle based on the of potentiometry, which involves measuring the voltage difference (potential) between a reference electrode and a sensing electrode. The sensing electrode is typically a glass electrode containing a special pH-sensitive glass membrane that responds to changes in hydrogen ion concentration.
Working
The working of pH probes:
- a) Glass Electrode: The glass electrode consists of a thin glass membrane with a high resistance to ion flow. This membrane allows hydrogen ions to diffuse into it, establishing an equilibrium with the sample solution. As the hydrogen ion concentration in the solution changes, it induces a potential difference across the glass membrane.
- b) Reference Electrode: The reference electrode provides a stable reference potential against which the pH-sensitive glass electrode’s potential is measured. It is often filled with a gel or solution containing a stable reference electrode potential.
- c) Measurement Circuit: Connect the pH probe to a pH meter or analyzer via a measurement circuit. The pH meter measures the potential difference between the pH-sensitive glass electrode and the reference electrode, converting it into a pH value using calibration parameters.
Calibrations para meters: pH probes require regular calibration to maintain accuracy. Calibration involves immersing the pH probe in solutions with known pH values (buffer solutions). This ensures that the pH probe provides accurate and reliable measurements.
To ensure optimal performance and longevity of pH probes, proper care and maintenance are essential. Rinse the probe with distilled water after each use. Store it in a suitable storage solution, and follow the manufacturer’s guidelines for cleaning and maintenance.
Also read sources of impurities.