The Luminol Test

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Blood and other body fluids found at the scene of a crime may give important physical evidence in three ways;

	Occurrence of a blood strain in a certain place, e.g. on a weapon may substantiate an account of a crime.
	Shape, position, size or intensity of a bloodstain may support a particular sequence of events.
	Blood typing analysis can be used to eliminate whole groups of people as suspects.

It is thus obviously important to be able to identify a particular stain as blood or not, or maybe even to reveal "hidden" bloodstains on dark materials or where attempts have been made to wash the blood away.

Human blood contains a pigment called haemoglobin, which is used to transport oxygen around the body.


Ball and stick model	Space filling model
Haem group
The part of the haemoglobin molecule containing iron (the central green atom)

This pigment is used by a number of tests used to identify the presence of blood. One particular test that reveals the presence of blood is the Luminol Test. In this test the bloodstains can be made to glow with a blue light due to the chemiluminescent reaction of the luminol reagent with the iron in the haemoglobin.

The Luminol Reaction

(* indicates an electronically excited state)

Photograph by Donna Edwards, Deakin University


Suspected bloodstain on cloth?	Reveal by spraying with luminol in the dark

This test is sensitive enough to pick up minute traces of blood even when attempts have been made to wash away the incriminating evidence.

To find out more about the phenomenon of chemiluminescence and how it can be used visit the Deakin University Molecular Luminescence Group Home Page.

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Developed with support from the Science in Schools initiative of the Department of Education and Training, State Government of Victoria

Selected by the SciLinks program, a service of National Science Teachers Association (USA)

Blood and other body fluids found at the scene of a crime may give important physical evidence in three ways;

It is thus obviously important to be able to identify a particular stain as blood or not, or maybe even to reveal "hidden" bloodstains on dark materials or where attempts have been made to wash the blood away.

Haem group

The part of the haemoglobin molecule containing iron (the central green atom)

Photograph by Donna Edwards, Deakin University

The part of the haemoglobin molecule
containing iron (the central green atom)