What is the composition of Buffer RPE?

The exact composition of Buffer RPE is confidential. Buffer RPE is a mild washing buffer, and a proprietary component of RNeasy Kits. Its main function is to remove traces of salts, which are still on the column due to buffers used earlier in the protocol. Ethanol, which is added by the user just before using the kit for the first time, is an important ingredient of Buffer RPE.