We offer several different purification schemes. They offer a range of capabilities and applications. Our most common method is reverse phase (RP) HPLC. We use C-18 columns for most of our work. The vast majority of our compounds are at least double purified, first undergoing a trityl-on prep, followed by another full HPLC purification after removal of the trityl group. This ensures a high level of both length and chemical purity, which is comparable or even superior in many cases to more sophisticated and costly anion exchange (AX) HPLC methods. We have demonstrated this to many customers and would be happy to demonstrate the same to you with a sample synthesis. We do offer AX-HPLC, but in a more limited capacity. Another popular method is polyacrylamide gel electrophoresis (PAGE). This method is limited to just a few tens of milligrams of material (15 μmole starting scale) and becomes expensive very quickly. It is a good method to enhance length purity, but is limited in its ability to remove chemical contaminants.