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How to Measure Light Emitted by Luminol

Luminol is a popular tool used by crime scene investigators to identify blood at a crime scene. This includes blood washed off by the criminal. The chemical is sprayed on an area and reacts to the iron in the blood, creating a chemical luminescence. The glow lasts about 30 seconds and the room or area must be dark for it to be readily visible. Since it produces light, there are ways to measure the luminosity of a Luminol glow.

Things You'll Need

Iron source, such as blood
Luminol
Hydrogen peroxide
Sodium hydroxide
Spray bottle
Light meter

Instructions

- 1
  Place the iron source on a flat table with nothing around it. Pour the powdered Luminol in the spray bottle. Add the two catalysts, hydrogen peroxide and sodium hydroxide, to the spray bottle. Shake well until the powder is completely dissolved.
- 2
  Turn out all the lights, so you are as close to complete darkness as possible. The Luminol gives off a low-intensity light, so this makes the glow easier to see and be read by the light meter.
- 3
  Spray the iron source with the Luminol mixture. The source should begin glowing immediately. The intensity of the glow depends on the brightness of the room and how much iron is in the source. Using more iron means a stronger reaction with the Luminol.
- 4
  Adjust the light meter to its most-sensitive setting, as the light will not be very intense. Put the light meter near the surface of the Luminol glow and take a reading. Do not let the meter touch the Luminol, but get it as close as possible. You only have 30 seconds to get a reading before the glow begins to fade. Turn on the lights. Read the light measurement from the meter, which will be given in lumens.

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