[Histonet] RE: Re: Methanol in H2O2 explanation

[Tony Henwood (SCHN)]

Hi Carl,

What do you mean by "Why do people rehydrate after dewaxing?" Do you really mean that slides do not require rehydration or do you mean that slides can be left to dry after de-waxing prior to staining.

Re-hydration is necessary, otherwise xylene will prevent aqueous stains from doing their thing efficiently.

I was lead to believe that as H2O2 was catalysed by endogenous peroxidase, the reactive oxygen reacted with the methanol to then degrade the enzyme, but I need to look closer at this chemistry.


Regards 
Tony Henwood JP, MSc, BAppSc, GradDipSysAnalys, CT(ASC), FFSc(RCPA) 
Laboratory Manager & Senior Scientist 
Tel: 612 9845 3306 
Fax: 612 9845 3318 
the children's hospital at westmead
Cnr Hawkesbury Road and Hainsworth Street, Westmead
Locked Bag 4001, Westmead NSW 2145, AUSTRALIA 


-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu [mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Hobbs, Carl
Sent: Wednesday, 11 July 2012 1:32 PM
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] Re: Methanol in H2O2 explanation

Why do some people use methanolic H2O2?
Why do people rehydrate after dewaxing?
Both are unnecessary, under usual conditions.

Methanol was used in the early days as a peroxidase blocker by itself.
The combination was devised as a "belt and bracer" method.
As you stated, you use aq H2O2 effectively.
So do I and many others.

However, for unfixed frozen sections, I would never use aq H2O2, if I wanted sections remaining on my slides....

After dewaxing, rinse sections in 4x 100% alcohol, rinse in water, endog. Px block while you make up you AR solutions....

Carl Hobbs
Histology and Imaging Manager
Wolfson CARD
School of Biomedical Sciences
Kings College London
Guys Campus
SE1 1UL
Tel: 020 78486813
Fax: 020 78486816
020 78486813


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