Clogging of the columns is sometimes observed with samples containing higher amounts of proteins (e.g. vaccines, high serum concentrations..). Even if proteins may not be the main component, they could be involved in the formation of complexes between proteins and other ingredients. We recommend to try a Proteinase K treatment according to the description of the manual of the VenorGeM sample preparation kit (optional step prior to the 70 °C incubation step).