Frequently, low pH is used to elute from immune affinity columns

e.g. Protein Science 27 (2018) 1083-1092

Article Selectable High-Yield Recombinant Protein Production in Huma...

"Reusability of anti‐GFP/YFP sepharose

The anti‐GFP nanobody binds very tightly to GFP/YFP, and protein cannot be removed using mild conditions. To regenerate the resin after use, we used a low pH wash (0.1 M glycine pH 2) to remove YFP and any remaining uncleaved YFP‐TOP2α from the resin. In this way, we have been able to reuse this resin ∼20 times with no noticeable loss of binding capacity [Fig. 4(I)], similar to other commonly used affinity matrices such as amylose–sepharose, glutathione–sepharose, or Ni–NTA."

"Regeneration of anti‐YFP/GFP sepharose

After TEV elution of TOP2α, resin was washed once with water, three times with three column volumes of 0.1 M glycine pH 2.0, then three column volumes of Lysis buffer. The loss of yellow color served as a visual indicator of YFP removal."

Antibody affinity columns are usually stored in the presence of sodium azide:

https://www.pacificimmunology.com/resources/antibody-characterization/affinity-purification/

"The column should be stored refrigerated in PBS, 0.02% sodium azide. Do not freeze."