Figure 3: Comparison of antibody systems in the ELISA detection of S. typhimurium. In a sandwich immunoassay, chemical (bleach/sodium hypochlorite; closed circles), heat-killed (closed triangles), irradiation-killed (open diamonds), and live (open squares) S. typhimurium (bacteria) were reacted with two separate antibody systems, one raised against heat-killed. (A) and the other raised against irradiation-killed. (B) Salmonella. Formation of colored product was measured and represented above as absorbance (at 405 nm) versus bacteria concentration.