How is vitamin C concentration measured?

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Offline VickiLacey

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How is vitamin C concentration measured?
« on: 17/06/2008 14:32:57 »
I am doing a research project in college looking into vitamin C deterioration in fresh orange juice. I have been diluting the orange juice with distilled water and acetic acid then titrating this dilution with DCPIP. The only thing is I am unsure of why I am using acetic acid. What does this do to the vitamin C? Why is it necessary for this titration? Can anyone help?? [:)]
« Last Edit: 18/06/2008 12:34:44 by chris »

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blakestyger

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Re: How is vitamin C concentration measured?
« Reply #1 on: 18/06/2008 12:25:28 »
It is usual with vitamin C determinations in plant (and animal) tissue to use a dilute solution (ca. 9%) of acetic acid to act as a tissue extractant. It is not actually reacting with the vitamin C itself.

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Offline iko

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How is vitamin C concentration measured?
« Reply #2 on: 18/06/2008 13:54:09 »
It is usual with vitamin C determinations in plant (and animal) tissue to use a dilute solution (ca. 9%) of acetic acid to act as a tissue extractant. It is not actually reacting with the vitamin C itself.

I knew that 10% trichloracetic acid (TCA) 1:1 denaturates proteins and stabilizes ascorbic acid by its strong acidity. This is a standard procedure for serum/plasma.
Then samples can be stocked at 4-8°C for weeks, protected from light until tested.
HPLC technology or old (Roe et al.1941) clinical chemistry methods can be used.
By HPLChromatography ascorbate and dehydroascorbate can be measured easily enough.


« Last Edit: 14/02/2009 12:19:26 by iko »


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Offline VitaminC

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How is vitamin C concentration measured?
« Reply #4 on: 16/09/2010 06:16:46 »

All I can think of is the acetic acid is acting as a buffer for the vitamin C, they have similar pKa values.

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Offline Bored chemist

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How is vitamin C concentration measured?
« Reply #5 on: 16/09/2010 06:50:04 »
Did you see the date of the original question?
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Offline benjamin1greer

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How is vitamin C concentration measured?
« Reply #6 on: 16/09/2010 08:08:44 »
Measure the vitamin C content of a sample of fruit juice by measuring the volume of the sample required to decolourise a solution of DCPIP. Calibrate the results by comparison with a known concentration of vitamin C.
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Offline Bored chemist

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How is vitamin C concentration measured?
« Reply #7 on: 16/09/2010 19:10:40 »
Did you really think that helped?
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