General Category > Equipment and Software
How to use a pH meter
bo:
Can you store them with the probe immersed in distilled water?
jmcamerlengo:
--- Quote from: bo on April 04, 2012, 05:21:01 AM ---Can you store them with the probe immersed in distilled water?
--- End quote ---
I've heard that this is bad practice.
nateo:
--- Quote from: jmcamerlengo on April 04, 2012, 08:57:29 AM ---I've heard that this is bad practice.
--- End quote ---
Yeah distilled water is corrosive. Storage solutions contain salts that will extend probe life.
oceanselv:
Storage solutions are indeed best to store the probes in. As for drying the probe, there is no need to completely dry the probe. As a bench chemist for 20 years, I have found a good rinse with distilled water and then a very gentle pat down with a paper towel will work fine. This will not induce a much of a static charge. I wouldn't use compressed air from a compressor to dry the probe as the compressed air typically has a small amount of compressor oil trapped in it. Also be careful of blowing on the probe to dry it as our breath also has saliva in it.
mabrungard:
--- Quote from: bo on April 04, 2012, 05:21:01 AM ---Can you store them with the probe immersed in distilled water?
--- End quote ---
No. The probe is filled with a ion-saturated (typically potassium) solution or gel. Its important to keep that solution saturated with that ion. The glass probe is actually permeable. Immersing the probe in a solution with very low ionic strength creates an osmotic pressure that draws those ions out of the probe and into the exterior solution. You end up depleting the ion solution inside the probe. pH probe storage solutions are typically high in the particular ion and when the probe is immersed in that solution, then there is not the osmotic stress drawing ions out of the probe. The probe solution stays saturated.
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