Page 1 of 1
Agilent XDB-C18 for determining vitamin C
Posted: Mon Jun 24, 2019 4:20 am
by Bessie
Hi
My laboratory provides me with Agilent XDB-C18 column. Is it suitable to determine vitamin C in fruits (apple, orange)? What are pros and cons of this column in this case?
Re: Agilent XDB-C18 for determining vitamin C
Posted: Mon Jun 24, 2019 5:52 am
by Rndirk
To get some retention for ascorbic acid on C18 columns, there are basically 2 approaches:
(1) Acidic (pH < 2), 100% aqueous mobile phase
(2) Make use of ion-pair agents
If you go for (1), this particular column might not be the best as it has an optimal pH range of 3-8. The second approach should work as the mobile phase is closer to neutral. You can find plenty of methods for ascorbic acid online. I believe (2) is the most common approach for ascorbic acid using reversed-phase.
Re: Agilent XDB-C18 for determining vitamin C
Posted: Mon Jun 24, 2019 1:36 pm
by Consumer Products Guy
Hi
My laboratory provides me with Agilent XDB-C18 column. Is it suitable to determine vitamin C in fruits (apple, orange)? What are pros and cons of this column in this case?
Also note for the future - one cannot make every assay fit a certain column or columns, your management must supply you with right tools to do the job.
A saw doesn't help much when a screwdriver is the right tool....
Re: Agilent XDB-C18 for determining vitamin C
Posted: Mon Jun 24, 2019 7:47 pm
by Vlad Orlovsky
If you need good retention control and peak shape along with mass spec compatibility you can try one of our approaches (two HILIC and one RP/anion-exchange).
https://helixchrom.com/compounds/ascorbic-acid/
You can spend tons of time with a wrong column and then end up buying a different one.
Let me know if you have questions.
Re: Agilent XDB-C18 for determining vitamin C
Posted: Mon Jun 24, 2019 9:56 pm
by HPLC chemist
Any (almost) C18 column can analyze Ascorbic Acid (I did with a 10 um Spherisorb back in the dark ages) but you have to remember to use ~10% meta-phoshoric acid (not ortho!) in your extraction media and mobile phase. It will prevent the formation of the anhydro analog of Ascorbic Acid.
Re: Agilent XDB-C18 for determining vitamin C
Posted: Tue Jul 02, 2019 11:20 am
by lmh
it's the extraction, not the chromatography, that's difficult. Extracting ascorbate without loss is very hard, and the common literature methods are actually rubbish, but no one dares admit it, because they've been around so long (sorry, feeling grumpy about this one).
Re: Agilent XDB-C18 for determining vitamin C
Posted: Tue Jul 02, 2019 3:49 pm
by James_Ball
it's the extraction, not the chromatography, that's difficult. Extracting ascorbate without loss is very hard, and the common literature methods are actually rubbish, but no one dares admit it, because they've been around so long (sorry, feeling grumpy about this one).
I can agree with that. I tried once for a combined method for Vitamin Bs and Vitamin C because it was listed in the example chromatograms that way, never did make it work. The Bs were stable and sensitive but the C recovery in standards was all over the charts.