Zip Tips -- these, C18 or C4 loaded pipette tips -- do a great job at desalting but they're pretty expensive when you have multiple samples. Is there a way to wash them so they can be reused? Has anyone had experience with this?
Like any reversed phase material, you can wash it with high organic (e.g. acetonitrile, isopropanol). It is usually not recommended to do that because the cost of contaminating your next sample is usually higher than the ca. 2 USD that you pay per tip.