Derivatization with MTBSTFA / problem

[no_peak]

Hi, I would like to ask for your opinion.

Why does my derivatization reaction with MTBSTFA not seem to proceed? I do not see any difference between the blank and a high-concentration standard.

At the moment, I am running the experiment using only neat standards of phenols and glycols. My procedure is as follows:

50 µL of the standard in LC–MS grade acetonitrile (water ≤ 0.01%),
50 µL of acetonitrile,
50 µL of MTBSTFA,
heated at 80 °C for 60 min,
cooled to room temperature,
then 1000 µL of n-hexane (FID/ECD grade) is added.
I collect the upper hexane layer and analyze it by GC–MS. The blank is prepared in the same way.

I do not observe any peaks corresponding to the phenols or glycols, despite the high concentration.

[itspip]

Is it possible that you're just derivitizing the water and there is not agent left for the phenols?

[Gizmo]

Pyridine in place of acetonitrile perhaps worth a shot

[no_peak]

Is it possible that you're just derivitizing the water and there is not agent left for the phenols?

It was my oversight—I assumed the background would be lower and that I would clearly see the target peaks in SCAN, even at a relatively high concentration. In the end, I had to increase the concentration by a factor of 10 to see them. It also turned out that the chromatogram becomes much clearer in SIM mode.
I think I didn’t expect such a high background after derivatization.

[Consumer Products Guy]

We derivatized a lot (mostly with BSTFA with TCMS). We typically used N,N-dimethylformamide as solvent for -OH groups, but when we needed to derivatize -NH groups we used pyridine and a few minutes on the steam bath.

We even used on products containing 85% water such as liquid soaps, just had to ensure excess of derivatizing agent.