We have a policy never to mix old and new working solutions in special
stains or immunohistochemistry. In IHC we use a commercially produced
antibody dilution buffer, which is supposed to keep diluted antibodies
stable at least a year. BUT you have to trial all your antibodies before
relying on this claim. One company's buffer works for me for all but one
antibody we use. For this one we found another buffer that does keep it
stable also.
Katri

Katri Tuomala
Anatomic Pathology
St.Joseph's Hospital
Hamilton, Ontario, Canada