Typical storage solvents for KNAUER RP columns are methanol/water or acetonitrile/water depending on the storage time. Is it necessary to store them for a longer time RP columns should flushed with acetonitrile/water. The KNAUER NP columns are stored under heptane/dioxan. Only the amino phase makes an exception. Amino columns are flushed with isopropanol so that application either in RP- or in NP mode is possible without problems. These columns are marked with a red label on the quality certificate.