In various industries such as food, medicine, medicine and pharmacy, agriculture and animal husbandry and water treatment plants, measuring the acidity of liquids is of particular importance, which is measured by pH meters today.

What is page meter?

The term pH is derived from the two words Power and Hydrogene and indicates the ionic strength of hydrogen in water. In other words, the ratio of ionized molecules to non-ionized molecules in the aqueous medium is called pH.

There are two ways to measure pH in laboratories:

1. Laboratory pH meter: It works by an electric circuit. The electric circuit itself consists of a glass electrode, an external reference electrode and a voltmeter to record the electric potential in the circuit.
2. pH measurement with colorimetric method: It is a chemical method that is done by adding a drop of acid-base indicator to the sample.

Types of laboratory pH meters

• pH pen meter:

This category of pH meters is small and light and is considered one of the cheapest available in the market and is less accurate than other types of pH meters.

• Portable pH meter:

which is more useful than the pen type and works with the electric energy of the battery. This sample has the ability to replace the electrode.

• You put the pH meter:

Unlike the previous two types, this category cannot be transported and must be placed in a fixed place. The pH meter on the table, which is also known as the laboratory type, has high accuracy and some of them have the ability to measure other parameters as well.

Structure of laboratory pH meter

The laboratory pH meter usually consists of two body parts, which include the screen, measuring plate, circuits, controls and interfaces, and the other part is the electrode. The electrode is a rod-shaped structure that is usually made of glass. At the end of the electrode is a bulb with a sensor specifically selected for hydrogen ion concentration. Electrodes must be connected to the device and stored in a buffer solution when not in use.

Calibration of pH meter

To have the best result, it is better to calibrate every day before performing the test, but if high precision is not required for measuring the sample, calibration once or twice a week is enough.

For calibration, at least two standard buffer solutions whose pH is known are needed. Today, some companies provide ready-made buffer solutions. In general, buffers with pH 4.00 and pH 10.00 are suitable for calibration. For more accurate measurements, it is better to measure the calibration in three different pH values, and after putting it in each buffer solution, wash it with deionized water or distilled water and shake it a bit to dry.

Tips to choose a laboratory pH meter:

1. Accuracy of pH meter measurement
2. How to install and use it
3. Ability to calibrate
4. The possibility of connecting to a computer
5. Sensor cable length
6. The resolution of the measuring device