The Metrosep A Supp 18 Guard/4.0 reliably protects the Metrosep A Supp 18 analytical separation column against contamination from sample or eluent. It contains the same separation material as the Metrosep A Supp 18 IC Columns, is also made of PEEK, and is screwed directly onto the respective separating column with virtually no dead volume ("On Column Guard System"). The guard column prolongs the service life of the analytical column, without influencing chromatographic separating efficiency.