[Doc888]

Has anyone got experience with Rosemount pH electrodes that will measure pH in silicate solutions ? The problem is that the silicate coats the bulb of the electrode and there is no more signal. This can happen in only a few hours. We have thought of using a salt bridge filled with saturated KCl and KCl crystals.
Thanks
Doc888

[Illuminatus]

Hi Doc888,

In your case, contamination seems unavoidable, better avoid electrodes entirely. I assume you need many timepoints for your pH, but do not want to keep changing your electrode; if your solution allows for it you should consider using a pH-sensitive indicator and tracking your pH by UV-spec instead. This requires more manual interaction but will yield data.

Note: Be sure to measure your samples as soon as you withdraw them, as the interior of either a plastic plate or cuvet can also become coated and muddy your absorbance readings. The hardest part here will likely be creating your standard curve; you will likely need to use an electrode alongside the dye for enough pH values to surround your measurement range.

Enjoy