Common Misconceptions in pH Electrode Use

pH electrode are core devices for monitoring the acidity and alkalinity of water. The accuracy of their data directly affects water quality assessment results. However, in daily use, many operational misunderstandings can lead to measurement deviations and even shorten the lifespan of the equipment.

Common Misconceptions in pH Electrode Use

1. The More Frequent the Calibration, the More Accurate the Data

Some users believe that frequent calibration guarantees data accuracy. In fact, the calibration interval of a pH sensor should be determined based on the operating environment. In stable, clean water conditions, calibration once a month is sufficient. If the water contains a large amount of impurities or chemical substances, the interval can be shortened to once every two weeks. Excessive calibration can accelerate electrode aging and negatively affect measurement stability. Before calibration, make sure the standard buffer solution is fresh. Using expired buffer solutions will result in an incorrect calibration reference.

2. Storing the Electrode in Pure Water

Soaking the electrode in pure water for “maintenance” actually disrupts the electrode’s internal balance. A pH electrode is filled with a special electrolyte. Long-term immersion in pure water will dilute this electrolyte, slow down the electrode response time, and increase measurement errors. The correct method is to store the pH electrode in a dedicated storage solution. If storage solution is temporarily unavailable, a pH 4 buffer solution can be used as a substitute.

3. Ignoring the Effect of Temperature on Measurement

pH measurement is significantly affected by temperature. The same water sample may show different pH readings at different temperatures. However, many users ignore the temperature compensation function and directly use readings measured at room temperature. Most pH sensors are equipped with a built-in temperature sensor. Make sure automatic temperature compensation (ATC) is enabled, or manually input the water temperature for correction. This step is especially essential in environments with large temperature variations.

4. Choosing the Installation Location Randomly

Simply placing the pH sensor anywhere in the water and starting measurement is a common mistake. If installed in areas with turbulent flow, air bubbles may adhere to the electrode surface, causing unstable readings. If placed near a discharge outlet, locally high concentrations of pollutants can interfere with the measurement results. The correct installation location should be in an area with stable flow and good representativeness, avoiding bubble formation and strong hydraulic impact.

5. Using the Electrode in Unsuitable Environments

Long-term use of the electrode in high-temperature conditions, strong alkaline solutions, or organic solvents can accelerate electrode aging and shorten its service life. pH electrodes are typically designed for aqueous solutions within a pH range of 1–12. Operation beyond this range or under extreme conditions will significantly reduce performance.

6. Wiping the Electrode Forcefully During Maintenance

When cleaning a pH electrode, applying excessive force or using hard tools to wipe the sensitive membrane can damage the glass membrane or the reference electrode, leading to measurement failure. The proper method is to gently blot the moisture with a soft tissue or rinse with deionized water and allow it to air dry. For stubborn contamination, the electrode can be soaked briefly in dilute hydrochloric acid, followed by thorough rinsing.

Avoiding these common mistakes helps keep the pH sensor in optimal working condition, ensuring reliable data for water quality monitoring and preventing decision-making errors caused by improper operation.