[OhyesOhno69]

What method is best to analyze vitamin c content in fruits? Is it spectrophotometer? Titration? Chromatography?

[Arkcon]

In your previous thread, you've been told that it can be difficult to prevent the ascorbic acid from decomposing before you analyze it, so the best method will rely on your ability to work quickly.

Titration is a perfectly valid way to quantitate any acid, but it will only give you a useful value if you've removed all other acids, and interfering substances.  That can be fairly simple or complicated, depending on the matrix.

There are a number of useful methods for qualifying and quantifying a mixture of organic acids by HPLC, if you have access to the equipment, and the technical experience.  If you don't understand that statement, then, you're not ready.

For the best results with the spectrophotometer, you should try to minimize the matrix effects with some sample workup, based on what techniques you can find.

[fulkon]

Here's two methods for ya:

1) http://www.camag.com/laboratory/methods/food.html

"Quantitative determination of Vitamin C in fruit juice"

This is a thin layer chromatography method.  You can get a qualitative result just by running the plates and observing the bands, but for a quantitative result you would use a densitometer.  This method covers all of that.  However, to view the method (which is in .pdf format) you have to sign up on the website.  But it's free!

2) "HPLC Assay for the Determination of Ascorbic Acid in Honey Samples". Castro, R.N., Azeredo, L.C., et al.  Journal of Liquid Chromatography and Rel. Technology., 24(7), 1015-1020 (2001)

So this is an HPLC method, and is very popular in analytical laboratories for many matrices.

Hope this helps!

[ARGOS++]

Dear Arkcon;

Thank you very much!,  ─    Sometimes it seems to be very hard to accept.

Good Luck!
                    ARGOS⁺⁺

P.S.:  To OhyesOhno69:  If you may have forgotten your previous Thread, Please go "here”
.

[Rivet]

If you can handle the problems of your matrix you may find an enzymatic analysis of ascorbic acid the way to go.  These are available as kits which from which you can scavenge the protocol to do as you wish.  I have not used this method personally, but we do a lot of these types of assays and I would be comfortable trying it for ascorbic acid

[Borek]

http://mailer.uwf.edu/listserv/wa.exe?A1=ind0802&L=chemed-l

Scroll down to see "Vitamin C Testing in Fresh Peppers" posts. Not much, but better then nothing.