Proper use and maintenance of pH meters

In all walks of life, especially in the fields of scientific research, environmental protection, industry and agriculture, pH meters (acidity meters) are increasingly used. Proper use and maintenance of pH meters is crucial to ensuring the accuracy of experimental data.

Fundamental

A pH meter is an instrument for measuring the pH of a solution, consisting of a reference electrode, a glass electrode and an ammeter. It determines the pH value of a solution by measuring its hydrogen ion concentration and is often used for accurate pH measurements.

Properly enable pH meter

Before use, the pH meter components should be assembled correctly, confirm that the voltage and frequency of the power supply and environment meet the instrument requirements, and ensure good grounding to maintain stable measurement. New glass electrodes need to be soaked in distilled water for more than 24 hours, and calomel electrodes need to be soaked in saturated potassium chloride solution to ensure their sensitivity and accuracy.

Preparation of standard buffer solution

Prepare pH standard buffer using pure reagents and distilled water. For example, buffers with pH=4.00, 6.88, and 9.18 need to be prepared in proportion using specific chemicals. The standard buffer solution should be stored in a dry place to avoid deliquescence and carbonation, which will affect the pH value.

Calibration of pH meter

Calibration is performed using two standard buffers, usually a pH=7 and a pH=4 or pH=9 buffer. Select an appropriate second buffer based on the acidity or alkalinity of the solution to be tested. Frequently used pH meters are recommended to be calibrated every 48 hours, especially after measuring extremely acidic or alkaline solutions, or after the electrode has been exposed to air for more than 0.5 hours.

Use and maintenance of pH electrode

When using, the rubber sleeve of the electrode liquid inlet and the rubber sleeve at the lower end should be removed to maintain the circulation of potassium chloride solution in the electrode. When not in use, the pH composite electrode should be soaked in 3 mol potassium chloride solution. Avoid using detergents or other water-absorbing reagents to clean electrodes. Regularly check whether the electrode bulb is intact and make sure there are no bubbles or cracks.

The correct use and maintenance of a pH meter can not only extend its service life, but also ensure the accuracy and reliability of experimental data. Therefore, mastering the operating details and maintenance skills of pH meters is crucial for professionals in related fields.