Forensic toxicology involves detecting and identifying drugs and poisons in body fluids, tissues, and organs to assist with criminal investigations and medical examinations. Toxicologists use a variety of screening techniques and confirmatory tests like gas chromatography-mass spectrometry to identify substances that may be present in only trace amounts. The body metabolizes substances over time, so the chemicals extracted from samples may differ from what was originally ingested. Toxicologists must also consider an individual's metabolism and published toxicity levels when interpreting the significance of any identified substances.

1. Forensic Toxicology

2. Toxicology toxicologist detect and identify drugs and poisons in body fluids tissues organs employed in crime laboratories medical examiner’s offices hospitals

3. Methodology toxicologist often presented body fluids and/or organs and asked to examine them for drugs & poisons many potential concerns/obstacles to this process usually no clue as to what type of substance will be present general screening employed to narrow down thousands of possibilities to just one item

4. Methodology presence of substances need to be identified when only nanograms or at best micrograms ( ɥ L) are present the body changes substances through it’s metabolism what was injected/ingested is not what is extracted

5. Methodology every chemical is processed and stored in different areas of the body = chemical fate when substance is detected, identified, and quantified a substance, the toxicity of the substance must be assessed published info to reference as far as toxic levels but… interpretations of cataloged information must be made to account for each individual case

6. Techniques specimen extracted identification of substance screening procedures gas chromatography thin layer chromatography immunoassay confirmation tests gas chromatography mass spectrometry

7. Techniques immunoassay predominantly a presumptive test creation of antibodies that are specific to a particular drug antigen-antibody reaction will take place if these antigens are added to a body fluid sample that contains the drug

8. Techniques immunoassay EMIT – Enzyme-Multiplied Immunoassay Technique to check someone for drug “A”, analyst will add “A” antibodies to the urine as well as chemically labeled drug “A” to the body any drug already in urine will compete with the labeled drug added to bind with the antibodies quantity of labeled drug left uncombined is measured this value is related to the amount of the drug originally in the urine sample

9. Techniques thin layer chromatography much like paper chromatography but with different materials gas chromatography liquid sample is vaporized into gas that is separated in chamber recorder graphs the peaks of gases separated each drug/substance has it’s own “signature” chromatogram

10. Techniques mass spectrometry an analytical tool to identify substances by the mass and abundance of its individual ions often linked to a gas chromatography chamber as the “recorder” if this GC/MS is linked to a computer, this system can detect and ID substances present in only one-millionth of a gram quantities

12. Techniques spectrophotometry an analytical tool to identify substances by the way the chemical absorbs different wavelengths of light can be accomplished with two different sets of wavelengths

13. Techniques spectrophotometry ultraviolet & visible wavelengths result is a UV/V spectrum does not provide a definitive result, rather establishes probable identity eliminates thousands of possibilities from consideration infrafred wavelengths result is an IR spectrum equivalent to a fingerprint for a specific substance