What is the principle of detecting blood stains with luminol?

 

I believe many people often see scenes of testing blood stains at crime scenes in the American TV series "CSI" and TVB's "Forensic Pioneer", and one of the more obvious testing methods is to use luminescent ammonia to determine. In 1928, it was first discovered that it could emit bright light when oxidized, and later it was continuously used to detect blood stains, especially in the fields of criminal investigation and chemical tracing. Using it for detection not only has high sensitivity but also has a reaction phenomenon to blood stains that have been sealed for a long time. So why is this? Why can blood stains that have been sealed for a long time be detected, and what is the principle behind it? Let's talk about it in detail below.

 

1、 What is luminol?

In fact, it is the same substance as Luminol, a very stable artificially prepared organic compound with the chemical name 3-aminobenzoyl hydrazine. At room temperature, its appearance is yellow powder, and as a strong acid, it cannot directly contact the skin or eyes, and has a certain irritating effect. Blood that cannot be observed with the naked eye at a crime scene can be displayed through it.

 

2、 The principle of detecting blood stains

When testing blood stains, due to the presence of hemoglobin in the bloodstains, the oxygen inhaled by the human body is transported to the whole body through this protein. Hemoglobin, in turn, contains iron, which, when catalyzed, decomposes into water and monooxygen, causing luminol to emit a bright blue light. This detection method is particularly agile, even if a small drop of blood that is not visible to the naked eye falls into a tank filled with water, it can be detected, and the amount of catalyst required for its reaction is very small, which can reduce the cost of use.

 

3、 Usage of Luminescent Ammonia

1. After washing with horseradish peroxidase markers, prepare to add luminescent ammonia substrate solution.

2. When adding luminescent ammonia substrate, equal volumes of chemiluminescent substrate solution A and chemiluminescent substrate solution B can be added.

3. According to the experimental requirements, add a corresponding amount of mixed substrate solution and place it in a dark place at room temperature for 5 minutes. Then perform the detection to obtain the result (luminescence value RLU).

 

Luminescent ammonia is an important and necessary reagent in luminescence experiments, and its quality determines its effectiveness. Therefore, when purchasing, it is important to focus on whether the quality meets the standard. As a professional supplier of luminescent ammonia luminol, Desheng has a product purity of up to 98%, rapid and stable luminescence, convenient use, and is conducive to various experimental detection. If you are not confident in using it under the guidance of professional R&D personnel, we guarantee worry free use. If you are interested, please click on the website for more information!