[Histonet] DAB freezing

[Alonso Martínez Canabal]

Hi everyone,
        I am doing free-floating immunohistochemistry with brain slices.
That is only the context. The issue is that I always prepare my DAB
(Hydrochloride sigma powder) aliquot it and store it in -20°C. But
recently, once I thaw it the DAB quality decreases a lot, to almost not
have any signal (I am used to almost black neurons with NiSO4). But all the
protocols that I have found say that is okay to make aliquots and store
them like that. Is there a stybilizer or something that I could use to make
the stock solution last? or my only option is to prepare it always
immediately before use?
Thank you!

-- 
Dr. Alonso Martínez Canabal PhD
Profesor Asociado "C"
Departamento de Biología Celular, Facultad de Ciencias, UNAM
Investigador Nacional "I"
56224833