The most common cause for pH measurement inaccuracies is an unclean or improperly cleaned electrode. 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. The calibration process compensates for the change in offset voltage. If the mV offset continues to deviate and the meter is calibrated with a dirty electrode then inaccurate readings will result. Immersing the electrode in the HI7061-23 cleaning solution for 15 to 20 minutes will dissolve any mineral deposits or other coatings.
In time, particles during routine measurement can contaminate the sensor tip. Mishandled and aged solutions can also be affected.
Your meter can still be calibrated even if the electrode sensor tip is not properly cleaned before calibration. If the contamination dissipates, the calibration is not valid and the readings are inaccurate.
A proper cleaning and fresh solution ensures the whole surface of the sensor tip is reading correctly, ensuring an accurate calibration and accurate readings.