Luminol Reaction - Criminal Identification - Lu Le Laboratory

Luminol is a versatile chemical that exhibits chemiluminescence, with a striking blue glow, when mixed with an appropriate oxidizing agent. It is a white to slightly yellow crystalline solid that is soluble in most polar organic solvents, but insoluble in water.

This is a five-gram packs

Luminol is used by forensic investigators to detect trace amounts of blood left at crime scenes as it reacts with iron found in hemoglobin. It is used by biologists in cellular assays for the detection of copper, iron, and cyanides, in addition to the detection of specific proteins by western blot.

For analysis of an area, 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 creating a slanted, or biased impression, such as blood traces appearing to be more concentrated in areas which received more spray. The intensity of the glow does not indicate the original amount present, but only the distribution of trace amounts of substances left in the area.

(Wikipedia)

 Mechanism:

 

Apparatus

1.      A PET bottle

2.      Funnel

3.      400mL beaker

Chemical

1.      Luminol: 0.06g

2.      Sodium carbonate: 1.70g

3.      Sodium bicarbonate: 7.20g

4.      Ammonium carbonate: 0.15g

5.      Cupric sulfate: 0.12g

6.      Aqueous hydrogen peroxide: 35% 1.5mL 

 

7.      Water: 300mL x2

Procedure

Making solution A

1.      Pour 300mL water in a PET bottle

2.      Place Luminol, Sodium carbonate, Sodium bicarbonate, Ammonium carbonate and cupric sulfate in the PET bottle and mix with water thoroughly.

Make Solution B

    Add 1.5mL 35% aqueous hydrogen peroxide in 300mL water in a beaker

Start the Reaction

1.      Set up a funnel on the top of the PET bottle.

2.      Turn off all the light in the room.

3.      Pour Solution B into the PET bottle and the reaction starts.

 The Blue Light can be seen in a bright room