This is our recommended regeneration procedure for RP packings C18, C8, C4, C1, C30, CN and Phenyl stationary phases:
Flush the column with 20 column volumes of water
Flush the column with 20 column volumes of acetonitrile
Flush the column with 5 column volumes of isopropanol
Flush the column with 20 column volumes of heptane
Flush the column with 5 column volumes of isopropanol
Flush the column with 20 column volumes of acetonitrile