For the coating of magnetic nanoparticles I intend to use tetraethylorthosilicate (TEOS). However I do not have much experience with this reagent. Could shared the precautions that must be taken?
The most critic precaution you have to take is to avoid the contact of TEOS reagent flask with water or humidity. Water hydrolises the TEOS and you loose the reagent. Keep the reagente at the refrigerator also.
I fully agree with colleague that you should be kept TEOS in a dry box (with nitrogen or argon). For more details about the chemistry of TEOS you can read in a relatively old (1979) but excellent monograph Iler R.K. "The chemistry of silica". That was my table book when I was doing my PhD dissertation/