The present disclosure relates to a method for detecting a core polypeptide of a hepatitis C virus (HCV) in a sample from a subject with the steps of (a) contacting the sample with a surfactant comprising a cationic detergent; (b) contacting the sample with a binding compound; and (c) detecting a core polypeptide of the HCV in the sample; wherein step a) is immediately followed by step b). The present disclosure further relates to a method for pre-processing a sample from a subject for detection of an HCV core polypeptide, involving (a) contacting the sample with a surfactant comprising a cationic detergent and, optionally, with an agent inducing a pH shift, immediately followed by (b) contacting the sample with a binding compound. Moreover, the present disclosure further relates to uses, devices, and analytical systems related to aforesaid methods.