how to seperate if the sample is very hard to dissolve

[moon704520]

I met with the sythesized sample ,there are about 4-5 isomers among the mixture which is very hard to dissolve ,and even though I run very low slope gradient ,the 4-5 compounds are very close ,futhermore the peak width is very large each !every compound is very basic ,and the MW is not very large !how should I do futher on the mobile phase and packing material ,we can pack column ourseves !many thanks !

[DR]

How large are the peaks?
If they're huge, making a more dilute preparation will help with respect to solubility and resolution.

[AdrianF]

What sort of solvents have you tried?
Are the isomers positional or optical?
Can you give more information as to the nature of the compounds.

[Uwe Neue]

Or: How do you control the pH? What buffer are you using? Details of the gradient? Injection solvent? ....................