Benchtop precision pH meter Hanna Instruments

A pH electrode that is properly manufactured and kept clean will retain its measuring integrity for quite a long time.

The most common cause for pH measurement inaccuracies is an unclean or improperly cleaned electrode. This is very important to note because, during calibration, the instrument assumes that the electrode is clean and that the standardization curve created during the calibration process will remain a valid reference until the next calibration.

pH meters on the market today will allow an offset of approximately ±60 mV. The deviation from 0 mV is not unusual, in fact it represents the true characteristics of the pH electrode. The deviation from 0 mV becomes a problem if it is the result of calibrating a dirty electrode.

HANNA instruments' HI 221 & HI 223 compare the characteristics of the pH electrode from one calibration to the next. In case of large variances in the electrode condition that can only be the result of a soiled sensor, these meters alert the user that the electrode needs to be properly cleaned prior to calibration and measuring.

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