The FOB Rapid Test is designed to detect lower levels of fecal occult blood than standard guaiac tests. The basis of the test is an immunochromatographic sandwich capture method which yields resulths that appear more specific to human hemoglobin and are easier to interpret than those of guaiac-based devices. The FOB Rapid Test employs an unique combination of monoclonal antibodies to selectively identify hemoglobin in test sapmles with a high degree of sensitivity . In five minutes, elevated levels of human hemoglobin as low as 12.5ug/ml are detected. With higher concentrations detected within one minute. In addition, unlike guaiac assays, the accuracy of the test is not affected by interfering substances and does not depend on the status of the patient at the time the specimen is taken. On the test strip, the membrane has been precoated with anti-human hemoglobin monoclonal antibody on the test region and goat anti-mouse antibody on the control region. In the test procedure, the sample fluid mixes are allowed to react with the human hemoglobin monoclonal antibody, which hass been conjugated with the colloidal gold particles. The mixture then moves upward on the memebrane chromatographically by the capillary action. For a positive specimen, a colored band with a specific antibody-hemoglobin-antibody-colloidal gold particle complex will form on the membrane in the test region. If human hemoglobin antigen is not present, no line will form in the test region. To serve as a procedural control, a colored band at the control region will always appear regardless of  the presence of human hemoglobin.