Forensic Chemistry is the application of chemical science or chemistry in solving or proving the crime in the court of law. Chemical science is being used for the analysis of pieces of evidence found at the scene of a crime.
Forensic science in the broadest sense utilizes the principles and methodologies associated with basic sciences for the criminal justice system. The analytical approach is making the findings acceptable by the judiciary.
It is the specialized subfield of forensic science. In day to day life, human beings are encountered with useful and useless chemical substances. Some chemicals like medication are helpful for treatment, but on the other hand, overdose and addiction may be associated with suspected deaths.
People are unaware of health hazards linked with the prolonged exposure of mercury, arsenic, insecticides and volatile poisons which may lead to sudden death. The tissue and visceral examination may be used for determining the cause of death.
A Brief History of Forensic Chemistry
The history of forensic chemistry is holding the facts of methods developed by a scientist for the identification and analysis of poisons, which were used for the commission of murders. The pieces of evidence of the use of poisons come from the early Egyptians, Romans, and Greeks.
Arsenic was the first poison for which the analytical test called as Marsh test was developed by British chemist James Marsh (1752). The next advancement comes from the development of Stas’s protocol (1850) by Jean Stas, which was used to identify the vegetable alkaloids in human tissues.
The development of a wide range of instrumental techniques aided in several forensic chemical analysis processes. Paper chromatography by botanist Makhail Tsvet (1906), found to be useful for the separation of individual substances from the mixtures.
The invention of the spectroscope in 1859 by Joseph Fraunhofer and its application for the identification of trace chemical shreds of evidence has proved to be beneficial. Modernization in the technology allowed the reliability of forensic chemists on numerous instrumental techniques for the identification of unknown chemical trace shreds of evidence found at the scene of the crime.
The invention of the atomic absorption spectrophotometer by Alan Wash for the detection and analysis of trace metal elements has helped in the detection of poisons like cadmium and arsenic.
- 1 Significance And Application Of Forensic Chemistry
- 2 Collection And Preservation Of The Chemical Evidences-Forensic Chemistry
- 3 Analytical Techniques Used For Specialised Cases
- 4 How to become a Forensic chemist?
Significance And Application Of Forensic Chemistry
Forensic Chemistry deals with the identification and analysis of chemical pieces of evidence found at the scene of a crime. These shreds of evidence are identified and examined for proving the diversity of crimes like homicides, sexual assaults, suicides, accidental poisoning, health and occupational hazards associated with metallic poisons, pesticides, insecticides, and others.
The example of some of the pieces of evidence is as follows:
- Identification of alcohol, narcotics, designer and commonly abused drugs like LSD, Cannabis, Opium Derivatives, Cocaine and others present in an unknown sample.
- Identification of synthetic and natural poisons such as arsenic, mercury, barium, cadmium, lead, croton, datura, calotropis, and others.
- Examination of petroleum products.
- Examination of inks, paints, dyes and other colouring agents.
- Analysis of firearm, explosive and arson residues.
- Examination and identification of trace metal elements.
- Examination and identification of volatile and flammable materials especially found in suspected cases of arson cases.
- Identification of adulteration in concrete, bricks and other building materials.
- Identification of level and concentration of alcohol, drugs, poisons in the blood, urine, hair and other human and animal biological materials.
- Identification of the composition of the pesticides and insecticides suspected poisoning deaths.
- Identification of the type of lubricant in sexual assault cases.
- Identification of the type of acid or alkali in the cases of chemical lab hazards.
- Identification of adulterants used in food items like milk products, spices, pulses, etc.
- Examination of blood, tissues, viscera in suspected poisoning cases.
- Examination of beauty cosmetics like lipsticks, eye shadow, face powders associated with allergies, and health ailments.
Collection And Preservation Of The Chemical Evidences-Forensic Chemistry
- Powder, pills, and solids: This evidence should be collected and preserved in the metallic pillbox, or a paper fold called a druggist fold and sealed with tape to prevent reaction with the external air.
- Petroleum products: These should be collected in airtight metallic containers.
- Acids and alkalis: Portable glass containers should be used. The containers should be labelled with alkali or acid.
- Blood, urine, and organs: These should also be preserved in the glass containers.
- Gunshot residues, explosive residues: These should be collected in airtight metallic containers.
- Other trace evidence like trace metal, cosmetics: These should be packed in ice cream containers, powder box, and metal pillbox.
Analytical Techniques Used For Specialised Cases
Identification Of Drugs And Poisons
Specialized techniques like gas chromatography, liquid chromatography, and high-performance liquid chromatography are useful for the identification of trace amounts of drugs and poisons obtained from a drug peddler to once obtained from post-mortem tissue matter.
Drunk And Drive Cases
The blood alcohol concentration estimation by gas chromatography is a suitable efficient technique for determining the quantity of alcohol in the blood. The chromatograph obtained can be useful for proving the fact that the person was drunk at the time of the crime.
Investigation Of Arson Cases
To set up a deliberate fire, a criminal may use a particular fuel to set up a fire as well as an accelerator which will increase the duration of fire at the chosen site. The fire residues can be collected in an airtight container to identify the type of fuel and accelerant used. Techniques like Gas-Liquid Chromatography-Mass Spectrometry can be proved to be useful for the quantitative estimation of the fuel.
Identification Of Gunshot Residues And Post-Explosion Residues
The gunshot residues and the post-explosion debris include the mixers of primer and propellants which can be identified by instrumental techniques like Scanning Electron Microscopy (SEM), Neutron Activation Analysis (NAA) and Energy Dispersive Spectrometry (EDS).
Dye And Ink Analysis
Techniques like paper and thin layer chromatography have been found useful in the separation of ink and dye components. Gel electrophoresis is also helpful for this procedure. The chemical analysis of ink is especially beneficial in the question document examination. The dye can exhibit toxic components which may have been the reason for death; therefore, the concentration and amount of the component is required to be known.
How to become a Forensic chemist?
Educational Requirement To Become A Forensic Chemist
A forensic chemist generally holds a bachelor’s degree in chemistry, toxicology, biochemistry, clinical chemistry, or any other science field like biology or physics. A master’s degree in chemistry, forensic science or forensic chemistry is a must to become a forensic chemist.
A doctoral degree in forensic chemistry will be beneficial to avail of a post of scientific officer in a forensic laboratory. Diploma and certificate courses are also available in forensic chemistry in government and private universities to provide knowledge of forensic chemistry to science graduates or school pass out who can avail jobs a laboratory assistant in the forensic chemistry department.
Specialists in such fields should have learned to perform detail experimental processes, and handling instruments to prove evidence beneficial for the conviction of the culprit.
A forensic chemist must have knowledge and experience in general, organic and analytical chemistry. A detailed theoretical and practical test is conducted by the private, and government agency or laboratory to recruit the forensic chemist.
Role Of A Forensic Chemist
- A forensic chemist works mainly in the laboratory as an employee of local, state or federal levels. Their duty is to perform repetitive chemical experiments and handling technical equipment to test, identify, and prove the importance of evidence in the court of law by making an elaborate and detailed scientific report which is called expert testimony.
- Forensic chemists must be capable of investing many hours of the day in applying the analytical techniques to the evidence and documenting every step of analysis then presenting and defending their work in the court of law.
- He can also visit the crime scene if called by police professionals or intentionally to obtain a piece of potent evidence from the scene which could be otherwise neglected by the crime investigation team. He is required to perform the tests keeping in mind the laboratory standards and referring to the protocols.
- Maintaining the daily records of the use of chemicals, equipment, type, serial number and other details of the evidence are also required to be recorded. A proper chain of custody is required to be maintained from the time the evidence is collected and preserved from the scene of the crime to examination and analysis in the laboratory to addressing it finely in the court of law.
- A job of a forensic chemist involves the testing and identification of the presence of illicit drugs, poisons, drugs prescribed by the doctor, alcohol samples, biological fluids like urine and blood for the existence of toxic substance and tissue samples. He must ensure that a small amount of sample should be used for a single experimental procedure.
- He must take precautions to prevent the contamination of the evidence during the tests. To avoid contamination, sterile and clean glassware and pieces of equipment should be used. They must wear special protective clothes while performing the laboratory tests covering their mouth to prevent saliva, head to prevent the contamination with scalp hair into the sample.
- To ensure the validity and accuracy of their report, a forensic chemist does a routine check over the chemicals that are in use for the purpose of experiments and instruments used for testing. Another concern should be in the prevention of the evidence from tampering and mishandling.
- A forensic chemist should ensure that the samples under observation should not be tempered or mishandled intentionally or unintentionally ruin the quality of the evidence, which could further on testing produce incorrect results and the evidence loses its integrity.
- A forensic chemist is required to present the expert testimony in a manner that it can be understandable by the jury as well as the general public. He is required to answer all the questions even if summoned for every trial of the case in which a piece of chemical evidence is involved.
- He must remain confident during direct and cross-examination and should remain stick to the correct opinion even though the opposition party may try to prove the outcomes of the scientific procedure false in front of the law.
- A forensic chemist should remain unbiased while examining the evidence. No manipulation should be allowed in the experimental procedure. No pre-opinion should be included in the testimony unless a detailed experimental procedure is performed.
Various Other Fields Where Forensic Chemistry Is Used
Apart from functioning in the forensic laboratories, these experts can only pursue a career in educating the students of forensic science or any other basic science or chemistry at bachelors, masters and PhD scholars. They can also use their knowledge, skill, and expertise in research and publication. They can also avail of a job in private labs, food industry, chemical industry, and hospitals.