Re: Methyl Green (Water wash)

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From:"J. A. Kiernan" <>
To:Janice Mahoney <>
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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