I need to analyze sugars in freeze-dried food using GC-FID. I don't see any new techniques for this. I see this mainly done by HPLC-ELSD and RID. I've seen old technique whereby pyridine is used, then oximated, then derivatized. I also heard that sugars can be extracted with MeOH:water, but then I need to dry extract. Then derivatize. Problem is removing water and drying.
Any help is appreciated.
Kindly check the following link that may be useful:
Recent Techniques in Nutrient Analysis for Food Composition Database
https://www.mdpi.com › pdf
Also, the following RG link:
Article Recent Techniques in Nutrient Analysis for Food Composition Database
GC will not work for this purpose - diractly. After some derivatization - maybe.
Use HILIC (HPLC).
Regards
GB
I can easily do sugar analysis by HPLC but my boss wants a GC method. I understand I will need to derivatize.
You need to perform derivatization, Oximation prior to BSTFA/MSTFA (in general TMS derivatization) is to convert carbonyl moieties of the sugars to aldoxime and ketoxime. This is a type of protocol that enhances the stability of the molecules and prepares them for TMS deriv.
You may exclude this step and try to identify sugars by employing BSTFA directly. Water and MeOH-like hydroxyl carrying groups must be removed as possible before the reaction since they ruin the reaction efficacy. You just need pyridine as a catalyzer and TMS reagent. It is a very simple and rapid reaction and can be performed in very small amounts. I am performing only 100-200 ul sugar riched supernatant (of course it depends on sugar composition but if you are indicating the RID which is a bulk detector, the sugar composition of your matrix must be in w/w% percentage). After evaporation of the 100 ul extract (by using N2 evaporation or vacuum concentrator) just add 1:1 pyridine and TMS reagent and incubate approx. 10-30 min (should be experimentally optimized) and inject directly to DB-5 or similar hydrophobic column. If the oximation will also be added (suggested) again use pyridine and hydroxylamine for reaction and add 200-250 ul of hydroxylamine in pyridine to tour dried residue and incubate for a short time. After this first step incubation just add the TMS reagent and incubate as the second. The very ease of use methodology if the GC is the only choice.
Good luck
Emir
Do I also need to dissolve sugar standards in MeOH/water solution and then derivatize in pyridine/BSTFA? Same as samples?
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