l-histidine functionalized multi-walled carbon nanotubes for on-line affinity separation and purification of immunoglobulin G in serum

► The multi-walled carbon nanotubes were covalently functionalized with l-histidine. ► His-MWNTs are used as online affinity adsorbents for IgG separation and purification. ► His-MWNTs based SPE adsorbent shows great potential in the affinity separation of proteins in complex matrix.