This fixative is for air dried frozen sections (overnight dry at room 
temperature), fix 5 minutes.  I have reused the fixative, but if you have a 
lot of humidity or fix a large number of slides, keep reuse time short, 
maybe a week.  I do store used fixative in a sealed bottle.

I NEVER use hydrogen peroxide in PBS, I use DAKO S2001 peroxidase block for 
minimally fixed frozen sections. This is made up in PBS, 0.03% hydrogen 
peroxide and some sodium azide.  IF you get your hydrogen peroxide 
concentration too high you will chew your sections off the slides.  This 
block is gentle for frozen sections.  I can make this up per publication 
method and I make up a supply for one week then discard the remainder.

At 03:52 PM 7/17/2004, you wrote:
>I do use freshly prepared fixative and h202 each time.
>Patsy
>
>-----Original Message-----
>From: histonet-bounces@lists.utsouthwestern.edu
>[mailto:histonet-bounces@lists.utsouthwestern.edu]On Behalf Of Jorge
>Ivan Zapata Valencia
>Sent: Saturday, May 15, 2004 12:46 AM
>To: histonet@lists.utsouthwestern.edu
>Subject: [Histonet] Fixative and H2O2 for frozen
>
>
>Hello everybody
>a technical question: may I use the same acetone:etanol mix to fix samples
>different days, or do I have to prepare it feshly every day?? The same with
>the H2O2 PBS solution for endogenous peroxidase blocking. Is it mandatory to
>use fresh one?
>Thank You very much
>
>jorge ivan zapata

Gayle Callis
MT,HT,HTL(ASCP)
Research Histopathology Supervisor
Veterinary Molecular Biology
Montana State University - Bozeman
PO Box 173610
Bozeman MT 59717-3610
406 994-6367 (lab with voice mail)
406 994-4303 (FAX)



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