pH Probe Maintenance

Several of our clients perform some of their own routine groundwater sample collection or wastewater monitoring. Parameters such as pH, conductivity, and temperature, commonly are measured in the field. Proper pH probe maintenance ensures a faster response, more reliable measurements, and a longer life. A few tips to get the most out of your pH probe are provided below.

The pH probe should be cleaned regularly according to the manufacturer’s recommended procedure and at a frequency dependent on the fluid being measured. Clean probes with a mild detergent solution. When deposits are difficult to remove from a probe, a diluted hypochlorite solution may be used, but it is always best to learn manufacturer’s cleaning instructions. Different probes require different cleaning methods. Calibration should be performed after every cleaning.

Many probes are sealed and the reference solution can’t be replaced; however, some have a small opening near the top of the probe where fresh solution can be added - check with the manufacturer of the probe regarding correct solutions and filling procedures. The reference electrode chamber should consistently have the appropriate amount of reference solution and without air bubbles. Most manufacturers recommend that probes should not be wiped; this is to prevent transfer of static charge onto the glass bulb resulting in slow or drifting readings.

If the probe is used routinely, store the probe in a pH 4 solution or a storage solution (usually obtainable from the manufacturer). If the probe isn’t used for weeks at a time, dry storage is recommended; however, immerse the probe in a pH solution, allow sufficient wetting time, and calibrate before proceeding with measurements. Storing the probe in distilled water isn’t recommended (the filling solution will become diluted and probe response will be slow). With proper maintenance, a probe will have an average life of two years.