[skatty]

I always try

DCM/methanol 
ethyl acetate/hexane.

recently I came across a paper using hexane/acetone and someone has suggested choloroform/hexane/methanol.

I wonder what other poeple use because i need some new systems

[macman104]

I'm a fan of EA/Hexane, but I know we've used Acetonitrile/Water and Ether/Hexane

[agrobert]

Really depends.

I get good separation of non-polar or less polar substituents with hexane/ethyl acetate.
I get good separation of polar compounds (sulfoxides, sulfones, alcohols) with DCM/MeOH or DCM/Acetone.

But yea I've seen DCM/hexane/MeOH used if DCM/MeOH is too polar.

[hmx9123]

It really does depend on your substrate.  Most of my stuff dissolves and runs in pentane.  Like with an R_f of 0.8 or higher on pure pentane.  Can't slow that down much without using reverse phase.  So, yeah, I use straight pentane a lot.  Because most of my stuff dissolves in pentane, I will use it as a starting point.  I'll add diethyl ether, about 2% at a time, to get stuff to change R_f.  This being said, I have run columns with pentane, any mix of pentane ether, methylene chloride, methylene chloride/pentane, ethyl acetate, ethyl acetate/methylene chloride, diethyl ether, THF, THF/hexane, THF/hexane/methylene chloride, xylenes, benzene, toluene, various combinations of these with pentane/hexane, and chloroform.  I've used others, but only rarely.

I really like how silica gel columns become translucent with the addition of methylene chloride or chloroform.

[agrobert]

Yea I've noticed that too.  Its much cooler to run a translucent column.  Makes things fun.  But then again I work with visibly fluorescent compounds anyways.