The invention relates to a method of isolating an immunoglobulin, comprising the steps of:



a) providing a separation matrix comprising at least 15 mg/ml multimers of immunoglobulin-binding alkali-stabilized Protein A domains covalently coupled to a porous support, wherein the porous support comprises cross-linked polymer particles having a volume-weighted median diameter (d50,v) of 56-70 micrometers and a dry solids weight of 55-80 mg/ml;
b) contacting a liquid sample comprising an immunoglobulin with the separation matrix;
c) washing the separation matrix with a washing liquid;
d) eluting the immunoglobulin from the separation matrix with an elution liquid; and
e) cleaning the separation matrix with a cleaning liquid comprising at least 0.5 M NaOH.