What forensic tests are done on blood?
Blood detection The most publicized test by crime shows is the Luminol process in which a chemical is sprayed onto a surface where blood is suspected to be. The chemical reacts with traces of blood, producing a chemi-luminescence, or apparent glow, as a result of the chemical reaction that occurs.
What are 2 examples of tests that can be done to detect blood at a crime scene?
Presumptive Tests
- Phenolphthalein Test. Also known as the Kastle Meyer Test.
- Luminol Test. How it works: A chemical compound, known as Luminol, is used in solution or sprayed onto suspected surfaces.
- Alternative Light Sources.
What kind of tests do forensic scientists use?
Common forensic science laboratory disciplines include forensic molecular biology (DNA), forensic chemistry, trace evidence examination (hairs and fibers, paints and polymers, glass, soil, etc.), latent fingerprint examination, firearms and toolmarks examination, handwriting analysis, fire and explosives examinations.
What are the presumptive tests for blood?
Luminol, leuchomalachite green, phenolphthalein, Hemastix, Hemident, and Bluestar are all used as presumptive tests for blood.
What are the 5 preliminary test for blood?
What are 3 examples of presumptive testing?
Examples
- Acid phosphatase test for semen.
- Cobalt thiocyanate test for cocaine.
- Duquenois-Levine reagent for marijuana.
- Kastle-Meyer test for blood.
- Malachite green test for blood.
- Marquis reagent for narcotics.
- Benzidine test for blood which changes from clear to blue in color with the presence of blood.
How is blood detected at a crime scene?
Luminol is a white-to-pale-yellow crystalline solid that is soluble in most polar organic solvents, but insoluble in water. Forensic investigators use luminol to detect trace amounts of blood at crime scenes, as it reacts with the iron in hemoglobin.
What are presumptive tests for blood?
The purpose of a presumptive test for blood is to determine whether or not it is likely that this body fluid is present; in other words, a positive result indicates the possibility of blood. A positive result of a confirmatory test for blood allows one to conclude that blood is present.
What is a common presumptive test for blood that can detect blood even if it is not visible to the naked eye?
Fluorescein is a presumptive blood test for latent bloodstain detection. It has been used in forensic applications to reveal trace amounts of blood. Traces of latent blood can be detected even after repeated cleansing of the crime scene.
How do you test for old blood?
What is a presumptive blood test?
A presumptive test is a qualitative analysis that allows to identify, or confirm, the presence of a substance in a sample. These determinations usually occur, after a chemical reaction, and a specific colour is produced.
How do forensic scientists test blood?
Extraction. DNA is located within the nucleus of cells throughout the body and the extraction step is responsible for breaking open the nucleus and releasing the DNA molecules into solution.
How does the Kastle-Meyer test detect blood?
In the Kastle-Meyer test, the chemical phenolphthalein is used to detect blood because phenolphthalein can change color if it comes in to contact with certain chemicals that are found in the blood. Specifically, phenolphthalein changes color if hemoglobin is present.
What is tested for during a routine blood test?
Red blood cell count,hemoglobin and hematocrit. The results of your red blood cell count,hemoglobin and hematocrit are related because they each measure aspects of your red blood cells.
“Luminol, leuchomalachite green, phenolphthalein, Hemastix, Hemident, and Bluestar are all used as presumptive tests for blood.” (2) “A presumptive test is a qualitative analysis that allows to identify, or confirm, the presence of a substance in a sample.