How Does The Luminol Test Work?

Forensic investigators use luminol to detect trace amounts of blood at crime scenes, as it reacts with the iron in hemoglobin.

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.

How does Luminol chemiluminescence work?

The basic idea of luminol is to reveal these traces with a light-producing chemical reaction between several chemicals and hemoglobin, an oxygen-carrying protein in the blood. This process, generally known as chemiluminescence, is the same phenomenon that makes fireflies and light sticks glow.

Does Luminol only show blood?

Luminol can detect the presence of blood at dilutions of up to 1:1,000,000, or 1 part per million. So, blue glow from luminol always equals blood, right?

How do you make luminol?

Avoid skin contact.

  • To prepare stock solution A, fill a beaker with 100 mL of water. Add 0.18 g of luminol and 3.0 mL of sodium hydroxide solution (1 M).
  • To prepare stock solution B, fill another beaker with 100 mL of water. Add 1 mL of hydrogen peroxide (3%) and 0.03 g of potassium ferricyanide.

What happens when luminol interacts with blood?

Luminol solution reacts with blood to produce light. The luminol solution contains both luminol (C8H7N3O2) and hydrogen peroxide (H2O2). The hydrogen peroxide reacts with the iron in blood to produce oxygen. This oxygen then reacts with the luminol, changing the structure of the molecule and temporarily adding energy.

Can luminol detect urine?

Luminol can detect the small amount of blood present in urine, and can be distorted if animals’ urine is present in the room being tested. Luminol reacts with faecal matter, causing the same glow as if it were blood.

Does UV light detect blood?

You see, blood does not fluoresce by applying UV or visible blue light. Although blood does not fluoresce, certain other physiological fluids will. UV alternate light sources can reveal the following: seminal fluid, saliva and urine stains. Also, certain narcotics will fluoresce as will bone and teeth fragments.

Can luminol detect bleach?

The forensic luminol test has long been valued for its ability to detect trace amounts of blood that are invisible to the naked eye. This is the first quantitative study to determine the effect on the luminol test when an attempt is made to clean bloodstained tiles with a known interfering catalyst (bleach).

What is Bluestar?

Bluestar is the common name for Bluestar Forensic, a more potent analog of luminol to detect traces of blood on crime scenes.

Does bleach get rid of blood evidence?

Murderers desperate to get rid of evidence might want to consider using bleach to wash away stains. But not just any bleach will do. When old-school chlorine-based bleach is splashed all over blood-stained clothing, even if the clothes are washed ten times, DNA is still detected.

What is the purpose of hydrogen peroxide?

Hydrogen peroxide is a mild antiseptic used on the skin to prevent infection of minor cuts, scrapes, and burns. The release of oxygen causes foaming, which helps to remove dead skin and clean the area.

What is luminol spray?

Luminol is a highly sensitive blood reagent used to detect latent bloodstain evidence, usually associated with a clean up subsequent to a bloodletting event. A strong steady chemiluminescent (Low blue light production) reaction takes place when the luminol formula is applied to blood, even in very trace amounts.

Is Luminol a presumptive test?

Luminol (Blood) The search for the presence of blood at a crime scene is normally done by close visual examination. Because the reaction is not specific to blood, a follow up presumptive test, such as phenolphthalein, is typically run on potential samples prior to collection.