I tried to purify 2g of the compound containing fatty acids by column chromatography but at the end I get fractions having minimum 2-3 components in each fraction...I need to purify the compound for various structural analysis like NMR and IR which need only single components..Please suggest some ways to do this as the fraction having 2-3 components is very little to be purified by column again.
You can try a recrystallization: choose the proper solvent in wich your fraction is soluble only when the solvent is hot but completely unsoluble when the solvent is at room temperature. Once you have selected the proper solvent, dissolve your fraction using heat and let the solution to freeze slowly. After a while your compound will appear as a solid. Recover it by decanting and repeat the procedure if necessary.
You can try solvents washes , try to find a solvent like PE for example where most of u
nwanted compounds are soluble and your interested one is not, or the opposite thing , and then try to do column chromatography . try either normal or reverse phase
I may
If you have a mixture of free fatty acids and other things, add a bit of NaOH and water to make basic, extract with hexane a few time to remove non-polar contaminants, then acidify with HCl, and extract the free fatty acids into hexane.
To purify individual fatty acids, given the quantity you are working with, I'd suggest a semi-preparative (10 mm x 250 mm) HPLC column. Depending on what fatty acids you have you could use either reverse phase or a silver ion column. The silver ion column will give you separation based on numbers of double bonds and double bond configuration. Search for silver ion, fatty acids, acetonitrile. For this method, the main solvent is hexane and just a small amount of acetonitrile. You'd likely be injecting < 1mg (~0.3 mg?) per run, so you'd have to do multiple runs and fraction collection.
If you have just a few fatty acids, and they have different numbers of double bonds and double bond configurations, you may be able to get away with separating these on a silver ion SPE column. Supelco has a technical sheet giving what solvents to use, but you might have to make some adjustments.
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