"Fred Meyering" > wrote in message
...
> G'day from down under.
> I was reading Tom S comment (18/04/05) on Ph and the correlation of the
> two digits after the point and the correct free SO2 levels. I have never
> heard of this before but that works a treat as a guide. It is always a bit
> of a challenge when wine making to get the right levels of SO2 in your
> wine so they are protected but still low so as not to upset delicate
> palates. How do you check your SO2 levels Tom S? We are using a
> refractometer which is good, but bloody sensitive.

??? I've never heard of measuring SO2 with a refractometer. Is that
something new, or are you speaking of a specific ion probe?

I usually do it the old fashioned way (the Ripper method):
Titrate an acidulated sample of wine against 0.02N iodine, using soluble
starch as an indicator. It's quick, cheap and accurate to ~ ±2ppm, but a
little tricky to do on very dark reds because of the difficulty seeing the
endpoint.

Tom S