Forensic science is a set of techniques that serve legal investigations and procedures. The range of forensic methods is extremely broad. Each of the traditional sciences can contribute to the crime scene investigations and legal disputes. From forensic astronomy to forensic chemistry and toxicology, DNA analysis, forensic archeology and anthropology, the list of forensic science subdivisions goes on and on. All of them provide investigators with an interpretation of the evidence collected, forming the basis for legal actions and decisions.

Forensic toxicology

One of the commonly used forensic methods is a forensic toxicology. Many of us heard about testing for the impaired drivers, that is an example of toxicology applications for the law enforcement.  A sample of the blood, urine, saliva, stomach contents or even hair should be collected for the analysis. Additional information gathered about the symptoms that the person under investigation experienced and any findings obtained that can suggest the use of poisonous substances. 

Blood test provides information about allegedly intoxicated person at the time of sample collection while urine sample can provide data about longer period. Hair sample can preserve information on toxic substances intake for several months and even years, thus enabling investigators to pinpoint the time of drug consumption. 

In the lab setting, scientists use quantitative and qualitative methods to determine which chemical is found in a biological sample and what is its concentration. Particular technique can be chosen depending on the type of substance investigated.

Forensic chemistry

Forensic chemistry developed as a branch of forensic toxicology, providing it with analytical instruments.

Chemists use two primary methods to identify toxic substances. Those methods are often employed jointly.

Gas chromatography is a method of separation of different chemical compounds so that they can be individually collected and examined. Separation is an important step, because biological samples may contain a large variety of molecules. Gas chromatography gives an idea about an amount of substance and its chemical characteristics. It is especially helpful for the analysis of organic compounds like formaldehyde, pesticides, and amphetamines.

Second method, called mass-spectroscopy, employed to identify the chemical substance. It is extremely powerful and precise and can identify both organic and inorganic components. It is very useful for toxic metal detection.

Both forensic chemistry and toxicology provide data that help to reconstruct the events of the crime scene, find out the cause of toxic effect in the case of an industrial accident or drug abuse.