Abstract: At least one alkyl paraben is used in an aqueous antimicrobial preservation composition for eliminating or reducing the microbial content of a microbially contaminated separation matrix, which is to be used in a housing of a separation device, the separation matrix being microbially contaminated. Also, in a method of producing a separation matrix with eliminated or reduced microbial content, the method comprises the steps of providing said separation matrix, microbially contaminated, in a housing or container; adding an aqueous antimicrobial preservation composition, which comprises at least one alkyl paraben, to said separation matrix in said housing or container; allowing said aqueous antimicrobial preservation composition to exert its effect in said housing or container until the number of colony forming units (CFU) per g preservative composition is sufficiently reduced; and rinsing said aqueous antimicrobial preservation composition from said housing or container.