Subtyping of group specific component (GC) in micro-bloodstains and semen stains by isoelectric focusing in ultrathin immobilized pH gradient gels followed by enzyme immunodetection.

A powerful method for group specific component (GC) subtyping with good resolution of GC bands by isoelectric focusing on ultrathin immobilized pH gradients is described. After separation, GC detection is achieved using a highly sensitive alkaline phosphatase conjugated enzyme-immuno system. The efficiency of the method in forensic case work for subtyping GC from diluted bloodstain extracts, blood micro-stains and semen stains is demonstrated. Furthermore, GC subtyping and selective detection of human GC provides the evidence for human origin of the stain. This is important when analyzing microstains with limited stain consumption.