Hach H160 User Manual page 15

ISFET pH probe maintenance
Multiple hazards. Only qualified personnel must conduct the tasks described in this section of the
document.
Chemical exposure hazard. Obey laboratory safety procedures and wear all of the personal protective
equipment appropriate to the chemicals that are handled. Refer to the current safety data sheets
(MSDS/SDS) for safety protocols.
The expected life of an ISFET probe is approximately 18 months. The reference electrode has a KCI
gel that is diluted over time. The reference is sealed and is non-refillable. Replace the probe when it
becomes difficult to calibrate.
• Keep the probe dry with the protective shroud on when not in use.
• Clean oil, fat, food particles, starch, protein or other materials from the probe tip after use.
• Never use sharp metal objects (e.g., a needle, a pin, etc.) to clean the sensor surface.
• Remove the probe from environments with static electricity. Electrostatic discharge (ESD) can
permanently damage the probe.
• Remove the probe from environments that will damage the sensor, such as hydrofluoric acid or
abrasive samples.
• Remove the probe from environments that will damage the epoxy materials used in the probe tip
(e.g., keep the probe away from acetone, toluene, methylene chloride, xylene and other strong
organic solvents).
• Do not use the probe in temperatures more than 60 ºC (140 ºF). Thermal cycling can decrease the
life of the probe.
• For semi-solids use, carefully twist the probe to make sufficient contact with the sample to the
sensor.
• When semi-solids are tested, make sure that solid objects (i.e., bone or gristle) do not scratch the
sensor.
• Cool samples to room temperature to maximize probe life.
• Always use new buffers and new rinse solutions.
Prepare the probe for storage
Do not use the probe for long-term pH measurement applications.
Note: No electrode storage solution is necessary.
A new probe usually has visible reference gel at the tip of the probe, as well as in the interior of the
rubber dust cap. To remove the gel, carefully clean with a soft-bristled toothbrush and mild soapy
water (a few drops of dish soap in a warm cup of water). The gel can continue to show for two to five
days. Do not put the rubber dust cap on the probe until all of the reference gel is removed. Do not
complete the steps that follow until all reference gel is removed from the probe and the interior and
exterior of the rubber dust cap.
Prepare the probe for storage
1. Put the new probe (or the probe that was in extended storage) in pH 7 buffer for at least
5 minutes.
2. Stir the probe in pH 7 buffer solution to dislodge air bubbles.
3. Use fresh deionized water to rinse the probe.
4. Dry the probe with a lint-free cloth.
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