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Topic: Need help with analyzing boric acid from a solution  (Read 1895 times)

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Offline Mused

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Need help with analyzing boric acid from a solution
« on: November 10, 2013, 12:50:53 PM »
Hello everyone,
Could you please help me with the following:
I have to make an analytical protocoll to measure boric acid from the following compound:
Acidum boricum...0,6 g
Tanninum...3,0 g
Glycerolum....10,0 g
Ethanolum 96%..10,0 g
Aqua purificata.....10,0 g

Now i thought of an acid-base titration with either phenolphtalein or potentiometry (any other method works? like GC-MS?)
I guess boric acid and glycerol makes a stronger acid which can be titrated with NaOH, but won't Tannic acid interfere? Should I precipitate it with some kind of metal first, then filter it?

Thanks for your help in advance!

Offline Arkcon

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Re: Need help with analyzing boric acid from a solution
« Reply #1 on: November 10, 2013, 02:35:08 PM »
Since this appears to be a pharmaceutical mixture, can you check the pharmacopeia for boric acid methods.  You guess right, that tannic acid will interfere with a titration.  Maybe you can still titrate, but also assay the tannic acid separately, then subtract?  Or can tannic acid be extracted away?
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline Mused

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Re: Need help with analyzing boric acid from a solution
« Reply #2 on: November 10, 2013, 04:45:25 PM »
The pharmacopoeia for boric acid only suggests acid-base titration with NaOH and phenolphtalein.
This is a manually made compund, so no method given. I think tannic acid can be extracted away, just not sure with what should I do it.

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