Re: PTAH (phosphotungstic acid hematoxylin)

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From:RUSS ALLISON <> (by way of histonet)
To:histonet <>
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One of the major problems with PTAH used to be that phosphotungstic
acid batches varied! I mean it!
We had all sorts of problems many years ago after exhausting a batch
of "home made"  PTAH.  I always used to say "how come the chemists
can order a reagent and get it virtually pure" with ALL impurities,
if there were any, listed on the label, order 100gms and get about
99.98% of that in the bottle.  Whereas histologists some times got
the ethyl dye, sometimes the methyl, sometimes as little as 50% total
dye content, masses of dextrin or any other filler and sometimes a
different dye altogether from the label.
Well, PTAH changed all that!  "Pure" (Analar, or whatever)
phosphotungstic acid was the downfall of our PTAH.  Bought a new,
cruder batch and it was all beautiful again - like a Montana sunset!
By the way Samurai, I still use Canada Balsam - it may fade some
stains a little, especially acid fuchsin, but I know all is safe and
redeemable in fifty years (which is more than you can say about some
Am I sounding like an old reactionary fuddy-duddy?
Russ Allison, Wales

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