Hello, what is your derivatization procedure? We use Pyridine-BSTFA-TMSCl (ratio 1:4:1) for GC/GC-MS analysis of extractives in wood samples. You are likely to have a complex mixture of polyphenols in your plant. Consequently, silylate in a test tube, add cap, put the silylated sample in an oven at 70 degrees Celsius for 30-45 min (shake the test tube after 10 minutes) for sufficient silylation, transfer into a GC vial and then run your analysis.