Filtration per se does not cause "rapid loss of staining quality" --
regardless of pore size.  However, the "very slow filtering" you've
described suggests you're using Harris hematoxylin, which typically throws a
surface precipitate when exposed to atmospheric oxygen.  That precipitate is
actually aluminum-hematein, which is the active complex responsible for
staining.  It forms because oxygen continues to oxidize initially unoxidized
hematoxylin, which forms so much more aluminum-hematein that it exceeds its
solubility limit in water.  Repeatedly removing this complex by filtering
over-and-over again causes the rapid loss of staining quality.

Mixing three parts of Harris hematoxylin with 1 part ethylene glycol fixes
the problem.  Aluminum-hematein is several times more soluble in 20%
ethylene glycol than it is in water.

Gary Gill

-----Original Message-----
From: Nancy.Walker@sanofi-synthelabo.com
[mailto:Nancy.Walker@sanofi-synthelabo.com] 
Sent: Tuesday, February 24, 2004 8:24 AM
To: Histonet@lists.utsouthwestern.edu
Cc: histonet@lists.utsouthwestern.edu
Subject: [Histonet] filtering stains (what paper?)



----- Réacheminé par Nancy Walker/FR-LABEGE/RESEARCH/SANOFI le 24/02/04
14:14 -----
 

                      Nancy Walker

                                               Pour :
histonet@lists.utsouthwestern.edu                            
                      24/02/04 12:46           cc :

                                               Objet :  filtering stains
(what paper?)(Document link: Nancy Walker)  
 




What grade of filter paper is good for filtering hemalun? The paper we
recently bough(Whatman 113V) seems to retain too much (very slow filtering
with rapid loss of staining quality).

How many times do you refilter stains before discarding?

thanks again,

Nancy Walker
Molecular Biology Scientist

Sanofi-Synthelbo Research
B.P. 37 Labége Innopole
31676 LABEGE CEDEX FRANCE

nancy.walker@sanofi-synthelabo.com
tel : (33)561004179  fax :(33)561004001





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