what kind of wash buffer for AP labeled secondary?

Answer 1

We normally use TBST (Tris-buffered Saline + Tween20), but most places give you a recommended protocol with the antibody. If you got the Ab from someone else, just do a search on the Mfg's website, or with someone else who uses the Ab or sells the same kind. Might also make a difference to know what you're doing - ECL can be a bit different from immunostaining.