5 Tips for the Most Accurate pH Measurements

1. Keep electrode hydrated

Ideally, pH electrodes should be kept in a storage solution when not in use. Placing the electrode in a small glass filled with storage solution is suitable. An option for pocket meters is to place a small piece of sponge into the meter ’s cap and pour storage solution into the cap to wet the sponge. Pouring of any excess solution beforehand, the cap can then be placed on the meter. If a storage solution is not available the next best option is to use pH 4.01 buffer (pH 7.01 is also suitable to a lesser extent). Never store the electrode in in purified water.

2. Clean electrodes regularly

Clean the junction of your electrodes once a day or at least once a week to prevent junction clogging and to maintain accuracy. Immerse the electrode in the proper cleaning solution for at least 15 to 20 minutes. Hanna offers a wide range of cleaning solutions for general purpose and specific applications.

3. Rinse, do not wipe your electrode

Wiping the pH glass can produce a static charge which interferes with the pH reading of the electrode.

4. Calibrate electrode often

All pH electrodes need to be calibrated often for best accuracy. The frequency of calibration depends on how accurate you want to be – daily calibration is ideal.

5. Replace electrodes once a year

If your electrode takes too long to stabilise a reading, or readings fluctuate wildly, it is most likely time to replace the electrode. The typical life span of any pH electrode is from 6 months to 1.5 years.

Additional tips:

  • Calibration and storage solutions should be changed regularly (i.e. monthly)
  • Remember that the calibration is as only  as good the buffer being used (i.e. old or  contaminated buffer may not have the  same value on the label)
  • Calibration sachets, as opposed to  bottles, ensure that your buffer solution  is always fresh
  • If the meter takes an unusually long time  to get a stable reading, the junction may be clogged
  • Rinse the probe with purified water after each use.

Download  pH Best Practices guide

ph-best-practices

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