Are the ammonium salts exchanged after PAGE or HPLC purification at IDT?
Sodium salt exchange must be requested as an added service and is performed after an oligo is purified. Generally, salt exchange is requested when HPLC purified oligos will be used in live cells or animals. RP-HPLC purification can leave trace amounts of TEAA (Tetraethylammonium acetate) salts which can be toxic. During the process the residual TEAA salts are exchanged for harmless sodium.