Vernier Tech Info Library TIL #706

Question

What is the best way to clean the glass bulb of the pH electrode?

Answer

Generally, rinsing the electrode with distilled water after using should suffice. If the glass bulb looks dirty, you can rinse the electrode with warm water and a mild household dish washing detergent (not Alconox detergent).

If the electrode and bottle appear to have mold growing in or on them, you can clean with bleach to remove the mold.

1) Fill the storage bottle with a mixture of 1 part chlorine bleach to 3 or 4 parts water (careful! such a mixture is hazardous to your skin and eyes!) and soak the electrode for 8 minutes.
2) Thoroughly rinse both in cold or lukewarm water.
3) Refill the bottle with pH Storage Solution and return the sensor to the bottle.

In biological labs where proteins are used, the glass bulb can get fairly dirty. In this case, do the following:

1) Soak the electrode for 10-15 minutes in an acidic pepsin mixture. Approximately 5% pepsin in a 0.001 M HCl solution should work (pepsin can be purchased through Flinn Scientific, order code P0006).
2) Thoroughly rinse the both in warm tap water.
3) Refill the bottle with pH Storage Solution and return the sensor to the bottle.

Created by: dholmquist on August 30 2000
Last updated by: rjohnson on October 21 2009