Is it normal to receive a Red-Rod electrode with salt in and on the probe?

Document ID

Document ID TE4939

Version

Version 5.0

Status

Status Published

Published Date

Published Date 05/30/2019
Question
Is it normal to receive a Red-Rod electrode with salt in and on the probe?
Summary
Salt on and in Red-Rod electrode
Answer
Red-Rod electrodes use saturated KCl as a reference solution rather than the 3M KCl reference solution found in non Red-Rod electrodes. Any loss of water from that solution as a result of evaporation may leave behind salt crystals. It is normal to receive a probe with salt build up in and around the outside of the probe. This can simply be rinsed off with warm demineralized water. There should be some salt crystals free flowing in suspension in the internal filling solution to maintain saturation even at higher temperatures, this is also the reason salt crystals are in the tip of the bulb. If the probe does not have any salt crystals in the filling solution, some can be added with Filling Solution, Reference, KCl Crystals (KCl.C) 15 g (Product # S21M001).

It's also not uncommon for some of the salt crystals inside the filling solution to clump during long term storage. Clumped crystals can clog the junction and restrict electrolyte flow. This is often resolved by following the instructions in What is the procedure for replacing the filling solution in a refillable pH probe?

See also:
What is the procedure for and purpose of adding KCl crystals to the filling solution of a Red Rod electrode?
What are the recommended steps to take to prepare a laboratory pH probe for first use?

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