I have a plant extract, for which I tried derivatization using MSTFA and pyridine. But I did not get any derivatives. Can you please suggest something?
We use Pyridine-BSTFA-TMSCl (ratio 1:4:1) for GC and/or GC-MS analysis of extractives in wood samples. Your question doesn't state which plant the extract is from, but if you suspect a complex mixture of polyphenols you could do the following: 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.Good luck.
Dear Jan-Erik Raitanen and Robin Joshi, thanks a lot for your valuable suggestions. I am looking for diterpenoids, sesquiterpenes in my extract...
MSTFA is used to replace labile hydrogens on compounds that have carboxylic acid or hydroxyl groups in order to make those compounds less polar and sufficiently volatile for GC. The diterpenoids and sesquiterpenes you mentioned do not have such hydrogens but do have diphosphate groups which may be way to polar for GC. Investigate further or consider LC.
Hi Thomas Schmitt, Thanks for your suggestion...the diterpenoids in my plant occur in conjugate forms, their show the presence of hydroxyl groups. On this basis, I selected MSTFA as the reagent, and pyridine as the catalyst.
I have used a premade solution of HDMS:TMCS:Pyridine to silanize cholesterol, oxysterols and thujinol, all terpenoids. Then separate using an HP-5, SAC-5, 5-MS or any of those type packings.
That's why Pyridine used for derivatization usually is dried using KOH pellets. HMDS (or BSTFA or MSTFA)+TMCS+pyridine has greater silylating potential than HMDS/BSTFA/MSTFA alone and makes the derivatization proceed faster.
Thank you all for your suggestions!! I would surely look into the same..
And ya, I had taken care that my vial, sample, pyridine, everything was moisture free..
Thanks..
Add 2 times BSTFA as the H acive sites (excess BSTFA+1%TMS) and pyridine. Be sure pyridine is dry. 1 hours at 70 C and voila TMS derivatives. The killer is water in the air, or solvent. Hope this help
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