I am doing derivatization of different flavonoids (Quercetin, morin, rutin, luteolin, apigenin-7- glucoside, luteolin-7-glucosie, catechin, taxifolin) using BSTFA and TMCS reagent (99:1 ratio) for GC/MS analysis. However I got always a peak which does not correspond to my flavonoid analyte, where the NIST library identifies it as fatty acid.
I do the derivatization as follows: the standard is dissolved in minimum amount of methanol, then ethyl acetate is added, followed by the derivatizing agent . the resulting solution is then heated at 100 C for 90 minutes, and then one micro liter is injected into the GC/MS.
You need to use pyridine with BSTFA to achieve a successful derivatization. Besides of that, I think that for glucoside derivatives there is a problem with the selected separation/detection technique. GC-MS is not suitable for compounds of such high molecular weight and therefore you need to work with LC-UV or DAD for these compounds. Quercetin and catechin can be analyzed by GC-MS, but the others…will be really difficult to achieve adequate results.
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