[pure-silver] Re: D-76 and variations
- From: "John Black" <jblack@xxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Tue, 29 Nov 2005 13:58:23 -0500
> I found this article on the practical storage performance of various D76
> derivatives: http://www.udmercy.edu/crna/agm/phenvitc.htm
>
I generally agree with his findings but the work is at least 5 years old and
has some gaps in it. For instance, XTOL presently contains dimezone-S not
phenidone. The patent formula published for Xtol in A&T lists dimezone-S I
believe (where have I put that book...). The aqueous longevity of
dimezone-S is much longer than phenidone, even in heavy sulfite solution. I
cannot keep water stock solutions containing phenidone for 6 months. Even
with large amounts of sulfite, it rarely lasts more than a few weeks.
Phenidone solutions in glycols last quite well for a year or more as long as
water doesn't enter the picture until right before use.
> It is well written and laid out, so we can make our own judgement on the
> experimental thoroughness and repeatability.
His inability to derive a straight line for dry phenidone activity may
indeed be due to his lack of precision in weighing. This would need to be
repeated with a better balance. His Xtol activity vrs time curve is a bit
erratic. Since it is made from the same stock solution each time, it should
be flatter. There was obviously another variable at work.
The most interesting data from his activity/time chart was the stability of
dry phenidone. I have read several sources (A&T for one) that contends that
phenidone in the dry state is quite unstable and should not be more than
6-12 months old for use. I am still working on a bottle of dry phenidone
that is over 7 years old and still as active as when new. It has been stored
in amber glass, tightly stoppered at room temperature.
>
> Interestingly, it throws suspicion on plastic containers wrt D76 keeping
> qualities.
Some plastics are indeed quite gas permeable. I don't know which are the
best but PETG seems to be almost as good as glass. Glass is however cheap,
plentiful and reusable. I use glass and shall continue to do so.
JB
=============================================================================================================
To unsubscribe from this list, go to www.freelists.org and logon to your
account (the same e-mail address and password you set-up when you subscribed,)
and unsubscribe from there.
Other related posts:
