RE: [Histonet] Re: DAB precipitate

From:Gayle Callis

With Pierce DAB two liquid component kits, the DAB portion is kept in a 
freezer, although it does not freeze due to the solvent it is dissolved in, 
and there was and probably still is a ready to use DAB from Research 
Genetics(? and under a new name (?) was kept in a freezer and taken out for 

At 10:14 AM 4/21/2006, you wrote:
>I thought DAB should not be frozen????
>Patsy Ruegg, HT(ASCP)QIHC
>IHCtech, LLC
>Fitzsimmons BioScience Park
>12635 Montview Blvd. Suite 215
>Aurora, CO 80010
>wk email
>web site
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>-----Original Message-----
>[] On Behalf Of Pixley,
>Sarah (pixleysk)
>Sent: Friday, April 21, 2006 7:18 AM
>Subject: [Histonet] Re: DAB precipitate
>Dear Eva:
>I would like to hear any answers to this also. We always have a DAB
>precipitate. To avoid it, we make the DAB and add the nickel sulfate and
>H2O2 immediately before the reaction and do the reaction quickly. (Using
>nickel in the solution increases the precipitate significantly.) The longer
>you wait, the greater the precipitation. If I am doing a lot of samples, I
>set half the DAB aside and change solutions in the middle (add the nickel
>sulfate and H2O2). Otherwise, I don't know any other tricks.
>One other phenomenon I have seen is after freezing DAB. We make up our DAB
>solution in phosphate buffer (without H2O2 or nickel) and freeze the
>leftover. That works very well as long as you freeze in glass (i.e. new
>glass scintillation vials). If you freeze in some plastics, I have seen a
>precipitate upon thawing. And the glass has to be very clean--it cannot be
>something that was used before for DAB and then bleached and cleaned. Even
>if you clean the glass with a good cleaner like Chromerge or Contrad, there
>can be enough bleach leached into the glass to inactivate the DAB.
>Good luck and I hope to hear some interesting solutions to your problem!
>Sarah Pixley
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Gayle Callis
Research Histopathology Supervisor
Veterinary Molecular Biology
Montana State University - Bozeman
PO Box 173610
Bozeman MT 59717-3610
406 994-6367
406 994-4303 (FAX)

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