I am searching for a good way to desalt peptides prior to mass spectrometry. Until now, I used zip tips for volumes smaller than 100 µL and that worked fine. However, now I am dealing with larger volumes (which is due to my specific protocol). I found several companies that sell C18 cartridges but honestly I am not sure how to use them (do I need special equipment?). Can anybody recommend something to me?
Thanks a lot.
Hi!
Cartridges work fine. You can use them like a syringe. You don`t need special equipment except a concentrator since you have also larger elution volumes.
Waters Sep-Pak C18 work well. I think you can just stick them on a regular glass syringe or re-usable plastic syringe.
If you can get your compound on and off the C18, the Sep Pak cartridges work well.
First, condition the cartridge with an organic solvent, then wash with water. Next, add your peptide and salt mixture; it should not contain organic solvent. Then wash with water to remove salt. Finally, elute with organic solvent, As mentioned by Dr. Lenz, it can all be done with syringes.
For larger quantities, I list a similar methods for automated flash chromatography systems- useful for removing non-volatile solvents or desalting:
http://www.isco.com/WebProductFiles/Applications/101/Application_Notes/AN95_C18Aq%20Desalting.pdf
http://www.isco.com/WebProductFiles/Applications/101/Application_Notes/AN97_Removal%20of%20Non%20volatile%20Solvents.pdf
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