Thanks George, currently I am making my paraformaldehyde fresh I was just 
curious about other possibilities in the event that I am face with a 
situation whereby it  would be beneficial. In this life I'm learning that 
exploring all options pays off more often than not.



>From: "George Cole" 
>To: "'Atoska S. Gentry'" 
>Subject: RE: Re: [Histonet] Fwd: Shelf life of 20%
>Date: Fri, 26 Mar 2004 08:50:54 -0800
>X-Mailer: Microsoft Outlook, Build 10.0.2627
>Importance: Normal
>
>Atoska;
>I'm not being prudish----the again, maybe I am--- when I
>mention:----with any reagent that MIGHT go bad between uses---I always
>mixed it fresh just before use.  There seems to be a lot of time spent
>questioning back and forth on the Histonet about when mixtures go
>bad----this old retired  histotech noticed about 35 years ago, that I
>was worrying and fretting about freshness and usefulness of mixtures
>that took less time to make than it did to worry about. Those reagents
>that were bonified safe pre mixed, I used. They were very few.  Most of
>my routines began with mixing stains fresh in the quantity that would
>give good results with the number of sides I had to stain. Once this
>became a habit, it was far less complicated than crossing my fingers
>about the potency of my reagents and, as a result, quality raised its
>droopy head. The habit of dragging one's feet comes upon us kind of
>sneaky-like--- from behind. Being a little bit bright about routine
>tasks saves a lot of scrapes caused by dragging your self around.
>georgecole@ev1.net
>
>-----Original Message-----
>From: histonet-bounces@lists.utsouthwestern.edu
>[mailto:histonet-bounces@lists.utsouthwestern.edu] On Behalf Of Atoska
>S. Gentry
>Sent: Thursday, March 25, 2004 1:51 PM
>To: Histonet
>Subject: Fwd: Re: [Histonet] Fwd: Shelf life of 20%
>
>
>Yes, you're correct but, I'm not sure if I will be able to determine
>stability by visualization alone; because my 4% doesn't get cloudy after
>2
>weeks I've just been advised that it converts to formalin after that
>period
>of time. It is a pain to go into solution but thankfully the protocol I
>use
>recommends heating it until it reaches 65C then adding 3.6 ml of 1N NaOH
>to
>help dissolve the PFA. After cooling I Q.S. and dilute to 4% with
>Sorensen's Buffer. Will most definitely let you know if I get it figured
>out.
>
> >X-Sender: gcallis@gemini.msu.montana.edu
> >X-Mailer: QUALCOMM Windows Eudora Light Version 3.0.6 (32)
> >Date: Thu, 25 Mar 2004 14:28:37 -0700
> >To: "Atoska S. Gentry" 
> >From: Gayle Callis 
> >Subject: Re: [Histonet] Fwd: Shelf life of 20% PFA/ 0.1M PB
> >
> >Sounds like an experiment about to happen!  Can you get powder into
> >solution at 20% concentration, a solubility consideration?
> >
> >I make 4% weeks (usually 500 mls) in advance per than answer I gave,
>doing
> >it a day ahead is sometimes a bother - but it is a gamble to see if it
> >stays viable.  My EM tech made up 4% PFA in a Sorenson phosphate buffer
>and
> >he taught me the cloudy solution trick.  He kept his for weeks also,
>and
> >you know how picky EM is -----. Interesting that I can make it up,
>split
> >the batch I made, send one batch to a lab and keep other in my lab.
>Theirs
> >goes bad in a couple of weeks (lots of whining and long faces!) and
>mine
> >stays good for months.  One gal using it is sloppy and probably the
>reason
> >theirs always goes bad! Consequently, I don't volunteer to make it up
>for
> >them too often.
> >
> >If you find out shelf life on 20%, let me know. Have fun -
> >
> >Gayle
>
>Atoska S. Gentry B.S., HT(ASCP)
>Research Assistant III
>Scott-Ritchey Research Center
>College of Veterinary Medicine
>Auburn University, AL  36849
>Phone# (334)844-5579  Fax# (334)844-5850
>
>
>_______________________________________________
>Histonet mailing list
>Histonet@lists.utsouthwestern.edu
>http://lists.utsouthwestern.edu/mailman/listinfo/histonet

Atoska S. Gentry B.S., HT(ASCP)
Research Assistant III
Scott-Ritchey Research Center
College of Veterinary Medicine
Auburn University, AL  36849
Phone# (334)844-5579  Fax# (334)844-5850 


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