Validation studies of an immunochromatographic 1-Step test for the forensic identification of human blood

An immunochromatographic I-step test for the detection of fecal occult bloo d was evaluated for applicability for the forensic identification of human blood in stained material. The following experiments were conducted: 1) det ermination of the sensitivity and specificity of the assay; 2) evaluation o f different extraction media for bloodstains (sterile water, Tris buffer pH 7.5 provided in the test kit, 5% ammonia); 3) analysis of biological sampl es subjected to a variety of environmental insults; and 4) evaluation of ca sework samples. This immunochromatographic I-step occult blood test is specific for human ( primate) hemoglobin and is at least an order of magnitude more sensitive th an previous methods for detecting human hemoglobin in bloodstains. The anti gen is insensitive to a variety of environmental insults, except for exposu re to certain detergents and household bleaches and prolonged exposure to c ertain preparations of luminol. The entire assay can be conducted in field testing conditions within minute s. When in the laboratory the supernatant from a DNA extraction is used for the assay, there is essentially no consumption of DNA for determining the presence of human hemoglobin in a forensic sample. The data demonstrate tha t this test is robust and suitable for forensic analyses.