TA Testing

[dinolan]

Excuse me for being chemistry-ily challenged. I see there's different ways to test TA using one's pH meter. Some use .1 N or .2 N NaOH, some add water, and the claculations are different too.The simplest calculation seems to be for using .2 N, where the % of TA = the amount of NAOH in ml that you used to get to 8.2. That's simple, like me. I could only find .1 N solution locally. Anyone know if there's a conversion I can use to calculate my TA using that same process as for the .2 N?

 

[dinolan]

Think I'll use the formula Alison Crowe uses in The Wine Maker's Answer Book-
ml NaOH x normality of NaOH x 0.075 x 100 = g/100 ml TA x 100= g/l TA
ml of wine sample

I believe that formula's been posted here a few times

 

[Norske]

I use Sodium Hydroxide 0.1N and Phenolphthalein as an Indicator. I first put 5ml of wine sample into my vial, then I add enough distilled water to insure that my ph meter probe will be completely submerged, then I add 3 drops of Phenolphthalein indicator solution and twirl the vial to mix it well.
The I use a syringe and draw up 10mls of the 0.1N solution and add about a half mil at a time while watching my ph meter readout. Be sure to allow time for the ph meter to equalize as it will climb and fall as you start adding the solution. Continue adding small amounts while watching your meter. Be sure to add drop by drop as you get closer to 7 because it is real easy to overshoot. Then just walk it up to 8.2.
Once you hit 8.2, then just look at how many mils you used and multiply by 1.5. That will be your TA. For example, 5mils of 0.1N used = 5x1.5= 7.5
Always be sure to recalibrate your ph meter prior to testing.

 

[dinolan]

That's an easy one, too. Thanks

 

[SBWs]

I have a post on my BLOG explaining how to test acid with a pH meter and the formula and where the numbers come from.

Testing acid in wine with a pH meter

 

[dinolan]

Thanks Scott. Nice blog btw!