I believe it is a preservative.

> -----Original Message-----
> From:	Phyllis Davie [SMTP:pdavie@phenopath.com]
> Sent:	Tuesday, May 02, 2000 2:41 PM
> To:	Histonet
> Subject:	Mayer's hematoxylin and chloral hydrate
> 
> I have been having trouble with the hematoxylin counterstain for my 
> immunos.  It is generally weak, with poor nuclear detail.  I have been 
> purchasing Mayer's hematoxylin, and I have tried 4 different vendors now, 
> all with the same results.  My first question is; what can be causing 
> this weak staining, and what can I do to fix it?  (I have been 
> counterstaining from 4-15 minutes, and many times, the staining--poor as 
> it is--drops off markedly after just a few racks of slides)
> 
> The second part of my question is this;  We decided to make our own 
> Mayer's hematoxylin, but the recipe we found in the AFIP Laboratory 
> Methods in Histotechnology, p. 52, calls for 50g of chloral hydrate.  
> Unfortunately, chloral hydrate is a class IV DEA (Drug Enforcement 
> Agency) regulated substance, and no-one here has a DEA license.  Can 
> anyone tell me what is the purpose of the chloral hydrate in the 
> hematoxylin is?
> 
> Thank you
> 
> 
> 
> Phyllis Davie
> Clinical Laboratory Supervisor
> PhenoPath Laboratories
> Seattle, WA
> pdavie@phenopath.com
> (206)374-9009  phone
> (206)374-9009  fax
> 
>