The Metrosep C Supp 1 Guard/4.0 contains the C-Supp-1 column material and is used to protect Metrosep C-Supp-1 cation columns. Particles and contaminations are reliably retained, allowing the service life of the analytical separation column to be prolonged considerably. The Metrosep C Supp 1 Guard/4.0 also functions according to the "On Column Guard System" and is screwed directly onto the separation column with nearly no dead volume.