Luminol (LMN)

Luminol is a versatile chemical that exhibits chemiluminescence, with a striking blue glow, when mixed with an appropriate oxidizing agent. Luminol is a white-to-pale-yellow crystalline solid that is soluble in most polar organic solvents but is insoluble in water. Luminol is used by forensic investigators to detect trace amounts of blood left at crime scenes, as it reacts with iron found in hemoglobin. Luminol can be sprayed evenly across the area, and trace amounts of an activating oxidant will cause the luminol to emit a blue glow that can be seen in a darkened room. The glow lasts for about 30 seconds, but the effect can be documented by a long-exposure photograph. It is important that the spraying be evenly applied to avoid a biased impression, such as blood traces appearing to be more concentrated in areas that received more spray.