Why Must pH Electrodes Be Calibrated Regularly?
After a period of use, the asymmetric potential of the pH electrode will change significantly, so regular calibration is mandatory.
The frequency of standard calibration for pH electrodes depends on the sample type, electrode performance and measurement accuracy requirements. For high-precision measurement (≤±0.03 pH), timely calibration is required; for general-precision measurement (≤±0.1 pH), the electrode can be used continuously for two weeks or even longer after a single calibration. There is no need for frequent calibration as long as the displayed pH reading is accurate.
When unpacked and used within the validity period, the electrode performance shall comply with all requirements of this standard. Within the warranty period, if the electrode fails to function properly due to manufacturing defects, the manufacturer shall be responsible for repair or replacement. Therefore, the quality warranty period of the electrode is one year on the premise that the electrode has not been used. It is inaccurate to generally regard the service life of a pH electrode as one year.
What is the service life of a pH electrode?
Regarding the service life of pH electrodes, the national standard ZBN50003-88 stipulates as follows:"Warranty period of electrodes: Within one year from the manufacturing date marked on the electrode, when unpacked and put into use, the electrode shall fully meet all performance requirements specified in this standard. During the warranty period, if the electrode cannot work normally due to manufacturing reasons, the manufacturer shall provide repair or replacement services."
Hence, the one-year quality warranty is applicable only for unused electrodes. It is incorrect to simply define the electrode's service life as one year. The actual service life is greatly affected by the measuring medium and varies drastically in different media. In harsh working conditions, an electrode may only last about two months; while in mild media, it can serve for one year or even longer. Therefore, users are advised to purchase electrodes produced recently by the manufacturer. The shorter the storage time, the better the performance during application.
