The invention discloses a method of separating a biomolecule from at least one other component in a liquid, comprising a step of contacting said liquid with a separation matrix comprising a solid support and polymer chains bound to said solid support. The polymer chains comprise units derived from a first monomer of structure CH2═CH-L-X, where L is a covalent bond or an alkyl ether or hydroxysubstituted alkyl ether chain comprising 2-6 carbon atoms, and X is a sulfonate or phosphonate group.