Has anyone used the free SO2 kits from Accuvin?
I find it very difficult to use titrets (red wine)
Just wondering if the Accuvin kit is any better - easier to use?

I am in the process of finishing my basement - with a separate room for my
"Winery". Eventually I would like to get some good test equipment. Any
suggestions - especially for SO2 testing appreciated.

I've considered using the Accuvin SO2 testers, but haven't because of cost
and, more importantly, shelf life. Last July I wrote to Accuvin,
specifically concerning shelf life, and they wrote the following:

"The current shelf life of our tests in 11 months for pH, 7 months for
Malic, Lactic, TA and Residual Sugar, and for our newest kit, Free SO2, 4
months. We are working to extend the shelf lives with ongoing studies."


Their ease of use is certainly appealing - but until they have a better
shelf life I think I'll wait.

Prior to knowing about the Accuvin tests, I did purchase a
vacuum/aspiration set up - it is NOT cheap, and several solutions needed
have a shelf life of 1 year, but it seems to be very accurate. Besides cost
of the glassware and chemicals, the downside is the time it takes to set up
and run the analysis - if you have a number to do it will take a while (and
if I don't have a number to do, I don't want to take the time to set it up).

Ed



"Paul E. Lehmann" > wrote in message
...
> Has anyone used the free SO2 kits from Accuvin?
> I find it very difficult to use titrets (red wine)
> Just wondering if the Accuvin kit is any better - easier to use?
>
> I am in the process of finishing my basement - with a separate room for my
> "Winery". Eventually I would like to get some good test equipment. Any
> suggestions - especially for SO2 testing appreciated.

"Paul E. Lehmann" > wrote in message
...
> Any suggestions - especially for SO2 testing appreciated.

I've been running straight Ripper on my wines - even reds. It's quick and
easy to do once you get the hang of it. The most expensive part is the
0.02N iodine standard, but that lasts a long time if properly stored. Use a
10 ml graduated pipette instead of a burette; they're a _lot_ cheaper!

I find that diluting the sample 50:50 with distilled water helps make it
easier to see the end point in reds. It's also important to have well
prepared starch indicator or you'll have trouble seeing the endpoint - even
in whites.

Tom S

In article >,
says...
>
> "Paul E. Lehmann" > wrote in message
> ...
> > Any suggestions - especially for SO2 testing appreciated.
>
> I've been running straight Ripper on my wines - even reds. It's quick and
> easy to do once you get the hang of it. The most expensive part is the
> 0.02N iodine standard, but that lasts a long time if properly stored. Use a
> 10 ml graduated pipette instead of a burette; they're a _lot_ cheaper!
>
> I find that diluting the sample 50:50 with distilled water helps make it
> easier to see the end point in reds. It's also important to have well
> prepared starch indicator or you'll have trouble seeing the endpoint - even
> in whites.
>
> Tom S
>
>
>

Tom - any chance you have this method and how you do it documented
somewhere with your practical tips included?

thx,
dan

"Daniel Tortorici" > wrote in message
...
> Tom - any chance you have this method [Ripper SO2] and how you do it
> documented
> somewhere with your practical tips included?

The method is pretty straightforward:

Measure 50 ml of wine into a 500 ml wide mouth Erlenmeyer flask. (Textbooks
say to use a volumetric pipette to measure the wine, but a 50 ml Nalgene
graduated cylinder is plenty accurate enough.) Add ~5 drops of saturated
soluble starch solution (try saying _that_ fast 5 times!) and approximately
10 ml of 25% sulfuric acid. Titrate _immediately_ with 0.02N iodine
solution dispensed from a graduated 10 ml pipette, approaching the endpoint
dropwise while constantly swirling the flask. The endpoint is when the
solution develops a purple/black tinge that persists for ~15-20 seconds.

ppm free SO2 = 12.8 * ml iodine solution.

The endpoint is harder to see in red wines, but diluting the original sample
with distilled water helps a lot and doesn't change the result
significantly. Bear in mind that this titration has an accuracy of ± 5% or
so, and possibly worse if your technique isn't good or the iodine is stored
badly. Keep the iodine tightly sealed in an amber bottle and in a cool,
dark place between uses.

There's a similar procedure for measuring total SO2, but frankly I have
never bothered with it. It involves dissociating all the bound SO2 with
strong base before doing the Ripper titration. Commercial wineries are
required to document total SO2 because there's a legal limit, but home
winemakers needn't bother.

Tom S

Thanks Tom,

The soluble starch solution - is that something commercially available
or something you mix?

The 25% sulfuric acid, do you keep that stored or dilute it when you
need it?

"Daniel Tortorici" > wrote in message
...
> Thanks Tom,
>
> The soluble starch solution - is that something commercially available
> or something you mix?

Both. You buy the powder and mix it up as needed. It needs to be boiled
before use to work the best. It'll grow mold easily, so boil it before
storing too.

> The 25% sulfuric acid, do you keep that stored or dilute it when you
> need it?

I have a 3 liter jug of 98% which I add 1:3 to water to make up a pint at a
time. You want to be careful when mixing that stuff because it gets quite
hot. Always add the acid to water with plenty of stirring.

Tom S

> >
> > The soluble starch solution - is that something commercially available
> > or something you mix?
>
> Both. You buy the powder and mix it up as needed. It needs to be boiled
> before use to work the best. It'll grow mold easily, so boil it before
> storing too.
>

Thanks Tom,
Do you have a source or a link for the starch powder?

dan

"Daniel Tortorici" > wrote in message
...
>
> > >
> > > The soluble starch solution - is that something commercially available
> > > or something you mix?
> >
> > Both. You buy the powder and mix it up as needed. It needs to be
boiled
> > before use to work the best. It'll grow mold easily, so boil it before
> > storing too.
> >
>
> Thanks Tom,
> Do you have a source or a link for the starch powder?
>
> dan

Dan,
Go the grocery store and buy a box of corn starch.
Mix about 1/2 a teaspoon of starch in a cup of cold water.
Bring the cup of starch solution to a boil.
Use when cool.
Lum
Del Mar, California, USA