Labcode|5|: Blood Analysis (part 1: Detecting Blood)

The analysis of the properties and effects of serums (blood, semen, saliva, sweat, or fecal matter) is called serology. We'll concentrate here on the principal tests used to identify blood. According to Henry C. Lee, a forensics expert who has assisted law enforcement in over 6,000 major criminal investigations — including that of O. J. Simpson — blood evidence is found most often in "crimes of violence such as homicide, assault, and sexual assault." It may be in the form of fresh liquid, coagulated, dried, or as a small drop or stain, and each form involves a different method of preservation and collection.

In this LabCode article we will learn:

• What is Blood? (hhh formalities)
• How to detect blood (using Luminol)?
• How to make Luminol using domestically chemicals?
• Where you can buy it?

What is Blood?
Blood constitutes about eight percent of a person's weight (normally about five liters), and it circulates near the surface of the skin. Almost all trauma to the body, therefore, results in the shedding of blood. Its red color makes it readily apparent at crime scenes, and its residues are very difficult to completely remove. Blood residue has even been recovered from 100,000-year-old stone tools.
Laboratory testing can reveal whether a substance is indeed blood, whether the blood is of animal or human origin, and the blood group to which it belongs. This allows investigators to include or exclude persons as perpetrators or victims. The antigens that allow blood group testing, however, deteriorate with age or improper storage.The DNA contained in blood, on the other hand, is less subject to deterioration, and allows near-certain matching of blood residue to individuals with DNA profiling techniques.Through bloodstain pattern analysis, information about events can also be gained from the spatial distribution of bloodstains.
 liquid called plasma makes up about half of the content of blood. Plasma contains proteins that help blood to clot, transport substances through the blood, and perform other functions. Blood plasma also contains glucose and other dissolved nutrients.About half of blood volume is
composed of blood cells:
• Red blood cells, which carry oxygen to the tissues.
• White blood cells, which fight infections.
• Platelets, smaller cells that help blood to clot.

 
How to detect trace of blood?

The most used method is using the Luminol."Luminol (C8H7N3O2) is a versatile chemical that exhibits chemiluminescence, with a striking blue glow, when mixed with an appropriate oxidizing agent. Luminol is a white-to-pale-yellow crystalline solid that is soluble in most polar organic solvents but is insoluble in water.
Luminol is used by forensic investigators to detect trace amounts of blood left at crime scenes, as it reacts with iron found in hemoglobin. It is used by biologists in cellular assays for the detection of copper, iron, and cyanides, as well as of specific proteins by western blot.
Luminol can be sprayed evenly across the area, and trace amounts of an activating oxidant will cause the luminol to emit a blue glow that can be seen in a darkened room. The glow lasts for about 30 seconds, but the effect can be documented by a long-exposure photograph. It is important that the spraying be evenly applied to avoid a biased impression, such as blood traces appearing to be more concentrated in areas that received more spray. The intensity of the glow does not indicate the original amount present but indicates only the distribution of trace amounts of substances left in the area."-Wikipedia-
here is a video explaning how Luminol is used.

how to make Luminol?
here is a comlete guide to make Luminol using domestically chemicals:

and if you can't make it you can buy it, it is for sale in Amazon for 10$.
See you later :)