Dear Nikhil

In the past I have routinely silanised slides for IHC under standard conditions in a fume hood; Nothing untoward happens but not performing this process in an inert environment

Dear Nikhil:

IT's much simpler to use for silanization of  glass:    an anhydrous toluene solution of APTES.

There also will be no problems with storage of such a solution: no inert environment ; no vacuum, no silica bead drying agent.

I must counter the post from L Vladimirov with a caution. Our experience with anhydrous toluene is, you must keep the containers in a dry gas when you intend to store the solution for extended periods of time. Moisture from the air will contaminate the anhydrous solution and initiate self-condensation reactions of the APTES. Eventually, rather than a uniform monolayer, this will lead to agglomerates on a surface.

This could also be a sign of the difference between a dry climate in Moscow versus a wetter one in Alabama. Not having been in Moscow, I'm only guessing.

And, anhydrous to me may be different than anhydrous to you. We often wonder whether we need to use the additional step of running our supposedly anhydrous toluene over molecular sieves to lower the water content even further before use.

Finally, methanol might itself initiate self-condensation of APTES. You might research the literature to see whether further insights exist.

And ... when all else fails ... Do the experiments. Set up a sequence of bottles in a room, sample them on a weekly basis, and find out how "pure" the solution remains versus its starting point. Look for increases in self-polymerization. An organic chemist could likely help you assemble the required test protocols for this assay.