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My hands-on experience with SPE is not huge, so the answer to this question may be obvious:
I have collected an unknown colored impurity on Oasis-WAX, but I cannot elute it with NH4OH (5% NH4OH in MeOH in the application notes), due to degradation already on the SPE column. I can elute it with strong acid (50/50 fuming HCl and MeOH). TFA/MeOH does not work so the pH needs to be extremely low. The molecule is however stable in this HCl/MeOH solution - so that is not a problem. However:
1. The use of such a strong acid is not supported by the Oasis-manual, can that be a problem?
2. Are there any other SPE approaches that can work? The molecule has no retention on C18 material. I don't know much about the molecule, except that it has a very bright color and seems to be extremely acidic.
I have collected an unknown colored impurity on Oasis-WAX, but I cannot elute it with NH4OH (5% NH4OH in MeOH in the application notes), due to degradation already on the SPE column. I can elute it with strong acid (50/50 fuming HCl and MeOH). TFA/MeOH does not work so the pH needs to be extremely low. The molecule is however stable in this HCl/MeOH solution - so that is not a problem. However:
1. The use of such a strong acid is not supported by the Oasis-manual, can that be a problem?
2. Are there any other SPE approaches that can work? The molecule has no retention on C18 material. I don't know much about the molecule, except that it has a very bright color and seems to be extremely acidic.
