This is our recommended regeneration procedure of NP packings, Silica, Diol, Nitro and Amino stationary phases:
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
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