toluidine blue

Ross Koning koning at ECSUC.CTSTATEU.EDU
Wed Oct 8 09:03:02 EST 1997

At 8:35 AM -0400 10/8/97, Wilson Taylor wrote:
>Hello all,
>I use a simple aqueous solution of Toluidine Blue (0.2%) and have very good
>results with lignified cell walls (blue or blue green) (thanks to Sue Schen=
>for the lead and recipe - it beats phloroglucinol/HCl by a long shot!)
>Does anyone know of any advantage to the recipe below?  What is the aqueous
>sodium tetraborate for?
>Other suggestions for simple aqueous stains for fresh material would be
>welcome (Let's get some ANATOMISTS talking to one another here instead of
>all of those darned physiologists [tongue firmly in cheek])

Hi Wil!

I second your suggestion (and I'm a physiologist!).

I have used the simple aqueous Tol blue solution and my students
get fairly good results...but NEVER beating phloroglucinol/HCl.

The secret to Phloroglucinol is making the phloroglucinol
in an alcoholic solution.  I use HCl in a separate dropper
bottle diluted 1 conc HCl to 4 parts water (resulting in about
10% HCl final conc).  Apply the two drops to a specimen and
in about 10 seconds the results are spectacular.  For long-term
storage and classroom use, I prefer Nalgene dropper bottles
with unitary caps.  You never get more than one drop at a time
and nothing degrades in the acid.

What I don't like about Phloroglucinol is the corrosion you can
get on mechanical stages and the tips of objective lenses if
the students aren't meticulous with the acid...and promptly
removing the slides from the stages before storing the microscopes.
I'm excited to try the tetraborate addition to see if it improves
the contrast with Tol blue...that would be nice and might convince
me to switch away from Phloroglucinol.  The tol blue w/o borate
is just too murky to me.


Ross Koning                 | koning at
Biology Department          |
Eastern CT State University | phone: 860-465-5327
Willimantic, CT 06226 USA   | fax: 860-465-4479

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