Measurements using the sensION+™ 5021T pH Electrode take a very long time to stabilize. Why is this?

Document ID

Document ID TE3282

Version

Version 2.0

Status

Status Published

Published Date

Published Date 27/05/2017
Question
Measurements using the sensION+™ 5021T pH Electrode take a very long time to stabilize. Why is this?
Summary
Long stabilization of sensION+™ 5021T pH Electrode
Answer
The preparation of the 5021T electrode is very important and must be as follows:
     - Before measurement, move the plastic ring away from the tip.
     - Put the ring back in the original position for measurement. Air bubbles in or under the probe tip when submerged can cause slow stabilization or error in measurement.

However, if the calibration time (with pH buffers) is quick, it means the the problem may be in the sample itself:
     - Temperature: During the measure, the temperature needs to be constant.
     - Sample homogeneity: A solution in which sediments are formed has to be stirred in order to stay physically and chemically homogenous. A low buffering capacity, i.e. in samples with low or no salt content, CO2 from the atmosphere dissolves in such samples and will cause a change in pH.
     - Extreme pH Values: the response time of the electrode may increase
     - Partial aqueous sample: The response time of the electorde may increase.