Solubility of impurities.........
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By Bhaskar on Thursday, July 22, 2004 - 08:10 pm:

I have a compound with 7 impurities and I developed a method to resolve all the impurities. The problem is two of the impurities are not soluble in mobile phase or in any diluents. These two impurities are having solubility only in Dimethyl formamide. In this case how can I proceed further?

Can you please share your ideas..

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By anila on Thursday, July 22, 2004 - 10:01 pm:

Use some perchloric acid at low conc. to enhance the solubility or try at differnt pH of the diluent.

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By Basil on Friday, July 23, 2004 - 12:46 am:

The main problem is to be sure that when you prepare a sample solution, if this impurities are present in the sample then should be dissolved by your mobil phase.

Try dissolving all with a low percentage of DMF and then complete to all volume with your mobil phase (sometimes it's usefull).

Others possibilites:

Have you tried to change pH in order to help the impuirities to be dissolved ?. How about using a small quantity of THF or something less polar...

Good luck !!