27-01-2012, 02:53 PM
CHEMICAL IN Forensic science
[attachment=16718]
Forensic science is a term used to describe the actions taken by investigators in multidisciplinary fields for the examination of crime scenes and gathering of evidence to be used in prosecution of offenders in a court of law. The main use of forensic science is for purposes of law enforcement to investigate crimes such as murder, theft, or fraud. Forensic scientists are also involved in investigating accidents such as train or plane crashes to establish if they were accidental or a result of foul play. The techniques developed by forensic science are also used by the U.S. military to analyze the possibility of the presence of chemical weapons or high explosives, to test for propellant stabilizers, or to monitor compliance with international agreements regarding weapons of mass destruction.
DIFFERENT TYPES OF CHEMICALS IN FORENSIC LAB
There are four kinds of chemical reagents used to expose invisible, or latent, fingerprints. They
are cyanoacrylate, silver nitrate, iodine, and ninhydrin
Cyanoacrylate
The trade name for cyanoacrylate is super glue. Cyanoacrylate is the active ingredient that makes up 98% of Super Glue. This item has become a very practical and innovative forensic tool. When cyanoacrylate is heated or mixed with sodium hydroxide (NaOH), it releases fumes that interact with the amino acids that are found in the fingerprint residues found on an object, thus making a white print.
Silver Nitrate
Silver nitrate is a chemical ingredient found in black-and-white photographic film. When silver nitrate is applied to a latent fingerprint, the chloride found in fingerprint residue interacts with the silver nitrate and forms another compound called silver chloride. This new compound reveals a black or reddish-brown fingerprint in the presence of ultraviolet light.
Iodine
The third chemical used to reveal latent fingerprints is called iodine. When heated up, crystalline iodine releases iodine fumes into a fuming chamber, where the iodine interacts with the oils found in the latent print thus producing a brownish colored fingerprint. Unfortunately, this kind of print has a tendency to fade rather quickly. Therefore, it must be captured on film right away or fixed by spraying it with a "fixing solution" made of water and starch. This fixing solution allows the print to last for weeks or even months in lieu of a few minutes.
Ninhydrin
The fourth kind of chemical reagent used to reveal latent fingerprints is ninhydrin. Ninhydrin, also known as triketohydrindene hydrate, has been used for many years to reveal latent fingerprints. An object suspected of containing latent fingerprints is sprayed with a solution of ninhydrin. It may take several hours for the fingerprints to show up due to the fact that ninhydrin reacts very slowly with the oils found in the fingerprint. However, heating up the object to a temperature of 80 to 100 degrees Fahrenheit can reduce the reaction time. The resulting fingerprint will be a purple/blue print.
[attachment=16718]
Forensic science is a term used to describe the actions taken by investigators in multidisciplinary fields for the examination of crime scenes and gathering of evidence to be used in prosecution of offenders in a court of law. The main use of forensic science is for purposes of law enforcement to investigate crimes such as murder, theft, or fraud. Forensic scientists are also involved in investigating accidents such as train or plane crashes to establish if they were accidental or a result of foul play. The techniques developed by forensic science are also used by the U.S. military to analyze the possibility of the presence of chemical weapons or high explosives, to test for propellant stabilizers, or to monitor compliance with international agreements regarding weapons of mass destruction.
DIFFERENT TYPES OF CHEMICALS IN FORENSIC LAB
There are four kinds of chemical reagents used to expose invisible, or latent, fingerprints. They
are cyanoacrylate, silver nitrate, iodine, and ninhydrin
Cyanoacrylate
The trade name for cyanoacrylate is super glue. Cyanoacrylate is the active ingredient that makes up 98% of Super Glue. This item has become a very practical and innovative forensic tool. When cyanoacrylate is heated or mixed with sodium hydroxide (NaOH), it releases fumes that interact with the amino acids that are found in the fingerprint residues found on an object, thus making a white print.
Silver Nitrate
Silver nitrate is a chemical ingredient found in black-and-white photographic film. When silver nitrate is applied to a latent fingerprint, the chloride found in fingerprint residue interacts with the silver nitrate and forms another compound called silver chloride. This new compound reveals a black or reddish-brown fingerprint in the presence of ultraviolet light.
Iodine
The third chemical used to reveal latent fingerprints is called iodine. When heated up, crystalline iodine releases iodine fumes into a fuming chamber, where the iodine interacts with the oils found in the latent print thus producing a brownish colored fingerprint. Unfortunately, this kind of print has a tendency to fade rather quickly. Therefore, it must be captured on film right away or fixed by spraying it with a "fixing solution" made of water and starch. This fixing solution allows the print to last for weeks or even months in lieu of a few minutes.
Ninhydrin
The fourth kind of chemical reagent used to reveal latent fingerprints is ninhydrin. Ninhydrin, also known as triketohydrindene hydrate, has been used for many years to reveal latent fingerprints. An object suspected of containing latent fingerprints is sprayed with a solution of ninhydrin. It may take several hours for the fingerprints to show up due to the fact that ninhydrin reacts very slowly with the oils found in the fingerprint. However, heating up the object to a temperature of 80 to 100 degrees Fahrenheit can reduce the reaction time. The resulting fingerprint will be a purple/blue print.