In the forensic detection of blood, the catalyst is the iron present in haemoglobin. Laboratory settings often use potassium ferricyanide or potassium periodate for the catalyst. In the presence of a catalyst such as an iron or periodate compound, the hydrogen peroxide decomposes to form oxygen and water:Ģ H 2O 2 → O 2 + 2 H 2O H 2O 2 + KIO 4 → KIO 3 + O 2 + H 2O Usually, a solution containing hydrogen peroxide (H 2O 2) and hydroxide ions in water is the activator. To exhibit its luminescence, the luminol must be activated with an oxidant. The compound was first synthesized in Germany in 1902, but was not named "luminol" until 1934.
Reduction of the nitro group to an amino group with sodium dithionite (Na 2S 2O 4), via a transient hydroxylamine intermediate, produces luminol. An acyl substitution condensation reaction occurs, with loss of water, forming 3-nitrophthalhydrazide.
First, hydrazine (N 2H 4) is heated with the 3-nitrophthalic acid in a high-boiling solvent such as triethylene glycol and glycerol. Luminol is synthesized in a two-step process, beginning with 3-nitro phthalic acid.
#LUMINAR LIGHTING ACTIVATOR#
The glow is stronger in areas receiving more spray the intensity of the glow does not indicate the amount of blood or other activator present. The glow only lasts about 30 seconds, but can be documented photographically. When luminol is sprayed evenly across an area, trace amounts of an activating oxidant make the luminol emit a blue glow that can be seen in a darkened room. Biologists use it in cellular assays to detect copper, iron, cyanides, as well as specific proteins via western blotting. Luminol is a white-to-pale-yellow crystalline solid that is soluble in most polar organic solvents, but insoluble in water.įorensic investigators use luminol to detect trace amounts of blood at crime scenes, as it reacts with the iron in hemoglobin. Luminol (C 8H 7N 3O 2) is a chemical that exhibits chemiluminescence, with a blue glow, when mixed with an appropriate oxidizing agent.
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