Re: Methyl Green (Water wash)
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From: | "J. A. Kiernan" <jkiernan@julian.uwo.ca> |
To: | Janice Mahoney <jmahone@nmhs.org> |
Reply-To: | |
Date: | Wed, 15 Sep 1999 10:40:44 -0400 (EDT) |
Content-Type: | TEXT/PLAIN; charset=US-ASCII |
On Tue, 14 Sep 1999, Janice Mahoney wrote:
> Do you rinse in tap water after staining or deionized? Tap will
> wash out the stain. Good Luck
This is an astute observation, and indicates that Janice
gets unduly acidic water out of her tap. Acids extract basic
dyes, and methyl green is especially susceptible because it
is a hydrophilic compound and can be extracted even by neutral
water. Distilled or deionized water usually has a pH of about
5 because is quickly absorbs carbon dioxide from the air, and
this reacts with the water to form carbonic acid. Hard tap
water contains dissolved calcium bicarbonate becaues it has
been filtered through limestone, and often is neutral or even
slightly alkaline (pH 7 to 7.5).
To avoid washing out methyl green, rinse in slightly alkaline
water. Then shake off as much as you can, and dehydrate the
sections in 3 changes of absolute alcohol. (Alcohol-water
mixtures remove most dyes more vigorously than either liquid
alone. Often this is desired, but with methyl green you will
usually want to retain as much as possible in the sections.)
Hope this helps.
John Kiernan
London, Canada.
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