Host-cell protein (HCP) antibodies that detect high, medium, and low-molecular weight proteins are now available. Host-cell proteins are process-related impurities derived from a host-cell expression system that may be present in trace amounts in a final drug substance. HCP antibodies are used to detect these impurities in biologically based therapeutics. These newly developed antibodies have been evaluated using the 2D electrophoresis workflow and provide immunocoverage of E. coli HCP.