Sodium Hydroxide and Phenolphthalein

[winemaker_3352]

Does anybody know what the shelf life is for Sodium Hydroxide and Phenolphthalein??

I am getting some off readings from my TA test kit - I am waiting on my PH meter - should be here next week.


Normality = .10
NaOH used = 1.9ml
Sample Used = 3ml


TA instructions say:

Sample used X .25 = .475%

But using this equation:

i get - .57%

Not sure what to believe here...

 

[ibglowin]

First off why are you not using a pH meter!

You should get at least 6-9 months as long as its kept in a fridge or cool place and pretty full.

Thats a weird sample size. I use the More Wine TA test kit and IIRC it comes with 0.1N NaOH and requires a 5ml sample. The multiplication factor is 1.5

I would try it again with 5ml and use 1.5 as the factor.

 

[winemaker_3352]

I know i need a PH Meter - got one on order

Not sure why - that was just what the TA instructions said to do..

Use 3cc(ml) sample - add 3-4 drops of Phenolphthalein - then add the NaOH - how ever many cc(ml) were used - multiply that by .25.

How does the sample size make a difference??

Is the equation above an accurate one??

 

[winemaker_3352]

Ok - so i tried using a 5ml sample.

Normality = .10
NaOH used = 2.4ml
Sample Used = 5ml

% TA * .25 = .60

ppt sulphiric * 1.5 = 3.75

These readings seem better to me - BTW this is for a Chilean Pinot Noir...

 

[ibglowin]

If you used 2.4ml of (0.1N) NaOH for a 5ml sample then your TA is

2.4 X 1.5 = 3.6 G/L

Which is pretty low.

I would not mess with it until you get your pH meter and use it as the referee. Your eye may be off.

 

[winemaker_3352]

I don't think that what you had is g/l - it is ppt sulphiric.

2.4 X 1.5 = 3.6 ppt sulphiric not g/l..

AT least that is what my instructions say..


For a Pinot it is not really low..

I have seen a lot of pinot's around:

Acid 5.57 g/L
PH 3.64

So my TA was .60% or 3.6 ppt is not that far from these...

 

[ibglowin]

I have no idea what you are talking about. There is no such thing as sulphiric. You are titrating tartaric acid to an endpoint with sodium hydroxide. Why don't you take a look at these instructions.

More Wine TA Test Instructions

 

[winemaker_3352]

I guess every test kit is different - I am just going off what the crosby and baker test kit says.

Parts Per Thousand (European) same as % tartaric just a different way of calculating it.

The crosby and baker instructions say to multiply by .25 to get % tartaric and multiply by 1.6 to get the ppt sulfuric...

I do like the instructions you gave though - a little more in depth on the color change to look for.

will try again tomorrow morning - but i think my best bet is to wait for my Milwaukee SM102 PH Meter!!!

 

[BobF]

Jon - My kit is the same as yours. It includes conversions for both ppt sulphuric and g/l tartaric.

3ml sample and .1 NaOH. NaOH used X .25

 

[ibglowin]

Anybody got a link to those instructions from CB? Maybe I can make heads or tails of it if I can take a look at it.


You are going to love the pH meter. It will be like a Microwave for sure (how did I ever live without it)

 

[winemaker_3352]

Anybody got a link to those instructions from CB? Maybe I can make heads or tails of it if I can take a look at it.


You are going to love the pH meter. It will be like a Microwave for sure (how did I ever live without it)

I know - i can't wait for it to come in!!

I tried finding those instructions online - no luck. Let me do some more searching, if i find it I will send it...

 

[winemaker_3352]

Jon - My kit is the same as yours. It includes conversions for both ppt sulphuric and g/l tartaric.

3ml sample and .1 NaOH. NaOH used X .25

Good - I am not crazy then

 

[Julie]

roflmao, will I do have a ph meter but when I did not, the kit I used said to use 10 ml sample and .1 NaOH. NaOH used X .75!

 

[BobF]

Here's a copy:

 

[winemaker_3352]

Here's a copy:
View attachment 5404

That's it!! Like i said before - all TA instructions are different.


But using the C&B I get:

2.2 * .25 = .55

Using Mike's instructions:

3.7 * 1.5 = 5.55

So they came out to be the same - the key was figuring out the color to look for when titrating a red wine.

I was reading when it turned grey - but thanks to Mike's instructions i found that was wrong - i needed to titrate until it turned a greenish color...

 

[BobF]

My reds always turn grey. The only time I see green is when doing A/O

 

[grapeman]

The new Vinmetrica 200 meter is $165 and is a combination pH meter and TA test kit. Take a 5 ml sample in a beaker, add 15 ml water, drip sodium hydroxide until it beeps as it reaches 8.2. Then you take ml NaOH used and multiply by two for g/L. About as simple as it gets and quick too!

 

[winemaker_3352]

The new Vinmetrica 200 meter is $165 and is a combination pH meter and TA test kit. Take a 5 ml sample in a beaker, add 15 ml water, drip sodium hydroxide until it beeps as it reaches 8.2. Then you take ml NaOH used and multiply by two for g/L. About as simple as it gets and quick too!

Yeah - I am currently waiting on my Milwaukee SM102 to come in. This is not a PH/TA combo - but I think I can get a TA reading from the PH tests..

 

[grapeman]

Absolutely you can. I did it a lot and it works. The little extra money is worth it IMHO for the Vinmetrica. You can perform about 30 tests with the reagents and replacement Na0H is $15 - much cheaper than buying the kits for what they do.

 

[BobF]

Does the Vinmetrica test for malic?