Forensic Chemistry

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What is Forensic Chemistry?

Forensic chemistry is the method where you apply chemistry to assist in examining unknown materials found at a crime scene. This is done legally and chemists have a wide range of instruments and methods to use for this purpose.

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What Does a Forensic Chemist Do?

The role of a forensic chemist varies a lot. Primarily, they work in a lab and are hired either by the government (local, state or central) or a private investigation firm. In the lab, they test samples that are collected by detectives and investigators. These chemists are generally trained in organic chemistry and physics. Organic chemistry helps in letting the scientists run analysis on body samples to identify DNA. They also run toxicology screenings.

Wide knowledge of Physics is required in this field. Although chemists mostly work in labs, sometimes a forensic chemist who is familiar with physics is called into the crime scene to examine things such as blood patterns, the range of attack, whether the injury was intentional or accidental, etc. Chemists can also specialize in certain aspects such as arson-related chemicals which can be used to make fire or bombs (explosives).


Role of a Forensic Chemist

If you ask what forensic chemists do, here we try and explain who are forensic chemists and what involves their primary duties. A forensic chemist collects and analyses substances found in a crime scene and tries to map out how it might be related to the crime. There are various types of forensic chemists who specialize in certain aspects. These scientists use chemistry and involve trace materials, drugs and other substances to help solve crimes. 

In addition to this, they also use biology and physics to analyze samples and the crime scene. They use ultraviolet or infrared light, X-ray spectroscopy, Chromatography (gas, column, etc), and mass spectrometry as their analytical instruments to find evidence. They first try to use reversible methods to preserve the original samples so that they can carry out more tests if required.


Methods Used in Forensic Chemistry

There are several processes and methods used by forensic chemists when they carry out their work, Spectroscopy and Chromatography are the two main processes used in this field.

  • Spectroscopy: It is the study of absorption and emission of light and other radiation by the matter which is dependent on the wavelength of the radiation. It also refers to the interactions between electrons, protons and ions, and their interaction with other particles as related to their collision energy. It can be used when the sample is pure or a very common mixture. 

The main techniques are FTIR and AA. FTIR is a non-destructive process that uses infrared light to identify a substance. This is a quick and easy step in the analysis of some unknown substances. Whereas, AA or Atomic Absorption Spectroscopy is a destructive technique that can be used to determine the elements that make up an analyzed sample. It analyses by putting the sample in an extremely high heat source, thus breaking the atomic bonds leaving free atoms. This is exposed to radiation which makes the atoms move to a higher state and then check the corresponding wavelength associated with it. Due to the destructive nature of this method, it is generally used as a confirmatory technique.

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  • Chromatography: It is a process used to separate components of a mixture. The mixture is first dissolved in a substance called the mobile phase. Then, the mobile phase carries it through a second substance called the stationary phase. This leads to the separation of the mixture into two or more components. This technique is used for analyzing unknown mixtures which are broken down into individual parts allowing them to be examined separately. 

Thin-layer chromatography (TLC) can be used to analyze inks and dyes by extracting most of the individual substances. This is used to investigate notes or fibres left at the scene as the fabric company products have a slight difference and the cloth could be traced back to its buyer. High-performance liquid chromatography (HPLC) is used to extract non-volatile mixtures dissolved in a solution which would not be suitable for gas chromatography. This is useful in drug analysis. Gas chromatography (GC) performs the same function as liquid chromatography but for volatile mixtures. They can be used for investigations related to arson, poisoning, explosions, etc.

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Gas Chromatography


Why a Forensic Chemistry Degree?

Forensic chemists have a wide range of areas that they can jump into after acquiring their degree.

  • Analytical chemist

  • Biomedical scientist

  • Crime scene investigator

  • Detective

  • Forensic scientist

  • Scientific laboratory technician

  • Toxicologist

Your degree may also be useful in jobs like:

  • Secondary school teacher

  • Forensic computer analyst

  • Border Force officer/police officer

  • Science writer

FAQ (Frequently Asked Questions)

1. What are the methods used in forensic chemistry?

There are several methods used in forensic chemistry. Ultraviolet spectrometry helps differentiate between protein and nucleic acid (DNA) samples. Infrared spectrometry is used for the recognition of organic compounds within atoms that have different capacities to absorb radiations. X-ray helps identify foreign objects in a victim’s body. Gas chromatography separates volatile substances into components and is a very reliable technique (and highly reproducible too!). 


GC is usually connected to a mass spectrometer which breaks samples apart and separates them by mass and charge, HPLC (High-performance liquid chromatography) can also be connected to mass spectrometry to separate different types of drugs.  

2. What are some of the job opportunities that we can avail with our degree?

Following are some of the job opportunities we can avail with the degree:

  • Fingerprint analysts: They study and evaluate fingerprints in criminal investigations.

  • Evidence technician: Collects evidence at crime scenes, processes and transports it to storage locations.

  • Forensic science technicians: They work at crime scene investigations and are responsible for gathering and analyzing evidence (take photos, keep written records of evidence, etc.).

  • Forensic specialists: They assess physical evidence from the crime scene using chemical, instrumental and microscopic methods. (work with biological fluids, drugs, blood residue, etc.).

  • Forensic manager: Oversees the activities supporting criminal investigations.

  • Forensic engineer: Investigates structures that have failed or do not function properly. They analyze these structures that might have caused injury or property damage and find the cause.

  • Forensic psychologist: Perform psychological assessment of criminals, witnesses and defendants in legal proceedings, act as an expert witness in court, put out health treatment plans for prisoners and make recommendations for inmates’ parole.