I use TEA(triethylamine) to basify my silica gel. However, in some articles, i saw that silica gel dissolves in eluent when the polarity of eluent is increased when TEA is mixed with eluent.
There are two parts to this answer. One is pH, and the other is solvent polarity.
For example, if the solvent system is non-polar, one can run 2M or 7M ammonia in methanol on silica gel, but not more than 10% methanol containing ammonia in dichloromethane. There is a high concentration of base, but this particular solvent system is relatively non-polar. As the solvent system becomes more polar, the pH is much more important- keep the pH below 7.5 to avoid dissolving silica in polar solvent systems.
TEA in hexane/ethyl acetate is fine because the solvents aren't polar enough to dissolve silica, even with the TEA. Please note that you may need longer equilibration times if running an automated flash system such as a CombiFlash (7 to 10 column volumes is best) to get the TEA equilibra. If you are packing a column, pack it in solvents containing the TEA and that will condition the column.
I think is dissolved in certain concentration of basic medium............
if the mobile phase is basic, silica will dissolve. If a modifier is required, keep the mobile phase acidic.
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