chromatographic device and method of detecting an analyte in a blood sample.

A chromatography assay device for detecting the presence of an analyte in a blood sample comprising: a chromatography carrier which defines a path for fluid flow and supports capillary flow, an application site for said blood sample in contact fluid flow with said chromatographic carrier, a detection site on said separate chromatographic carrier from said application site having attached thereto a trapping substance bound non-diffusively a diffusively bound labeled substance located downstream of said application site, diffusively bound polycation for separating plasma or serum from said blood sample upstream of said current detection site and diffusively bound polyanion for neutralizing the polycation downstream of said current and current bound polycation 20 upstream of said detection site.