Since the elution order depends not only on the stationary and mobile phase, but also on the compounds examined, there is no universal eluotropic series.
The most important factors are:
- Charge.
Charged compounds are highly retained in straight phase chromatography. In practice acidic analytes require acidic eluents, and basic analytes basic eluents to reduce the charge.
Note that silica and alumina are alkaline in themselves due to the method of preparation. They may 'bleed' at high pH and high solvent polarity. - Hydrogen bonding.
Compounds that hydrogen bond are retained more strongly than those that do not. Eluents that can hydrogen bond appear more polar, all else being the same. - Polarity of the eluent.