Luminol (The Chemiluminescence of Luminol and bis(2,4,6-trichlorphenyl)oxalate (TCPO))
Luminol: The Blood Detector
Chemiluminescence takes its place among other spectroscopic techniques because of its inherent sensitivity and selectivity.
It requires:
no excitation source (as does fluorescence and phosphorescence)
only a single light detector such as a photomultiplier tube
no monochromator and often not even a filter Maybe this list should be entitled "What chemiluminescent system do not require." Although not as widely applicable as excitation spectroscopy, the detection limits for chemiluminescent methods can be 10 to 100 times lower than other luminescence techniques.
Luminol is a chemical that glows greenish-blue when it comes into contact with blood — even traces that are years old. To be exact, it reacts to hemoglobin, an oxygen-carrying protein in red-blood cells. Luminol is so sensitive, it can detect blood at 1 part per million. In other words, if there is one drop of blood within a container of 999,999 drops of water, luminol will glow.
But does a glow mean there's blood present? Not necessarily. Luminol reacts to some metals, paints, cleaning products and plant matter. However, the chemical's reaction to each differs in intensity; metals, for example, cause an immediate glow that quickly fades, while blood glows longer. A specialist can tell the difference, and then perform more conclusive tests to determine whether the blood is human.
Chemiluminescence takes its place among other spectroscopic techniques because of its inherent sensitivity and selectivity.
It requires:
no excitation source (as does fluorescence and phosphorescence)
only a single light detector such as a photomultiplier tube
no monochromator and often not even a filter Maybe this list should be entitled "What chemiluminescent system do not require." Although not as widely applicable as excitation spectroscopy, the detection limits for chemiluminescent methods can be 10 to 100 times lower than other luminescence techniques.
Luminol is a chemical that glows greenish-blue when it comes into contact with blood — even traces that are years old. To be exact, it reacts to hemoglobin, an oxygen-carrying protein in red-blood cells. Luminol is so sensitive, it can detect blood at 1 part per million. In other words, if there is one drop of blood within a container of 999,999 drops of water, luminol will glow.
But does a glow mean there's blood present? Not necessarily. Luminol reacts to some metals, paints, cleaning products and plant matter. However, the chemical's reaction to each differs in intensity; metals, for example, cause an immediate glow that quickly fades, while blood glows longer. A specialist can tell the difference, and then perform more conclusive tests to determine whether the blood is human.
