Ammonium Thiosulfate solution shelf life

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Rob - 25 Jan 2006 16:24 GMT

What is the shelf life of a 60% solution of ammonium thiosulfate?How do you
know when it has gone bad?

Thanks in advance,

Rob

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dan.c.quinn@att.net - 26 Jan 2006 01:03 GMT

I've nearly half left of a quart of P. Formulary's 60% brought
into inventory 12/03. All the bottles' contents look good. I've
been using it.

The quart was split into a few smaller boston round glass
bottles equiped with caps having Polycone or Polyseal
inserts. I use a splits method to portion out stock or
concentrates. Glass bottles with good seals, full
to the brim with undiluted contents, makes for
longer lived chemistry. Dan

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Tom Phillips - 26 Jan 2006 09:09 GMT

>> What is the shelf life of a 60% solution of ammonium thiosulfate?How

do you

>> know when it has gone bad?
>
> I've nearly half left of a quart of P. Formulary's 60% brought
> into inventory 12/03. All the bottles' contents look good. I've
> been using it.

Dan -- what do you mean by looks good?

> The quart was split into a few smaller boston round glass
> bottles equiped with caps having Polycone or Polyseal
> inserts. I use a splits method to portion out stock or
> concentrates. Glass bottles with good seals, full
> to the brim with undiluted contents, makes for
> longer lived chemistry. Dan

I'd agree but a test for fixing effectiveness
would seem more practical. I'd say it's good
for at least year or two depending on storage
but testing is the only way to determine
effectiveness. Wasn't aware there was any color
test.

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UC - 26 Jan 2006 14:43 GMT

When ammonium thiosulphate breaks down, sulphur precipitates out (as a
light-brown substance) and it acquires a strong sulphurous odor.

If it's clear, it should be good.

> >> What is the shelf life of a 60% solution of ammonium thiosulfate?How
> do you
[quoted text clipped - 19 lines]
> effectiveness. Wasn't aware there was any color
> test.

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dan.c.quinn@att.net - 26 Jan 2006 23:36 GMT

> I'd agree but a test for fixing effectiveness
> would seem more practical. I'd say it's good
> for at least year or two depending on storage
> but testing is the only way to determine
> effectiveness. Wasn't aware there was
> any color test.

Looks good? The solution of concentrate in the
glass bottles is crystal clear and has produced no
sediment.
Color test? Perhaps the ST-1 test; the sulfide test
for silver left in the emulsion.
Thiosulf-Ate might be thought of as sulf-Ite oxidized
by sulfur. Oxygen will displace the sulfur producing
sulfate. Elemental sulfur will form in the solution.
The clear or cleared solution should still be quite
usable. Caught early only a little sulfate will have
formed in the solution.
Here's a thought. Add a little sulfite. It may
rejuvenate an only little gone thiosulfate. Sodium
thiosulfate anhydrous might be thought of as the
ultimate concentrate. Dan

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