Silver Stain (Audi 5000 effect)

Paul N Hengen pnh at
Mon Apr 18 17:15:02 EST 1994

18 April 1994
Connie Rickey
Bio-Rad Laboratories
E-mail: crickey at

Dear Connie:

This week I had an unfortunate experience with a kit I purchased from Bio-Rad.
I was using the Silver Stain Plus Kit (Cat. No. 161-0449) for staining proteins
within a polyacrylamide gel.  I followed the procedure outlined in the
instructions and encountered a problem with STEP 3. Staining and Developing

In the protocol, it is written:

"While stirring rapidly, add 50 ml of the Development Accelerator Reagent
to the beaker."

Since I didn't know that I should add the entire 50 ml of solution at once to
avoid a milky white precipitate, I added it slowly by pipeting. When I saw some
precipitates form, I slowed down the pipetting which made matters worse.  I've
designated this the "Audi 5000 effect" as applying the brake only accelerates
the precipitation (That's a JOKE!!! ONLY A JOKE!!!) :-)

My gel was absolutely ruined by the staining solution when it precipitated.
I called Bio-Rad technical services and found out the problem is in the
writing of the protocol.  The addition of the three words "all at once" would
have saved me a week of work and some precious materials. It would be nice if
Bio-Rad were to correct the wording of this so others are not trapped as I

I'm also posting this letter so that others will not make the same mistake.

Thank You.


* Paul N. Hengen, Ph.D.                           /--------------------------/*
* National Cancer Institute                       |Internet: pnh at |*
* Laboratory of Mathematical Biology              |   Phone: (301) 846-5581  |*
* Frederick Cancer Research and Development Center|     FAX: (301) 846-5598  |*
* Frederick, Maryland 21702-1201 USA              /--------------------------/*

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