Toxicology Student Notes

These notes are based on the textbook, “Criminalistics: An Introduction to Forensic Science” by Saperstein pp. 277-287 and includes information from different websites

Toxicology is the study of toxins i.e. poisons. Toxins can be natural or synthetic poisons. For example, in 1982 seven people died in the Chicago area after taking over the counter Tylenol capsules containing cyanide. The killer was never discovered. Johnson and Johnson still offer a $100,000 reward for the prosecution and conviction of the perpetrator ( This case resulted in the current types of protective packaging of products in order to prevent product tampering. A naturally occurring toxin is Tetrodotoxin found in Puffer fish which can be fatal (

Drugs can cause physiological or psychological effects. These substances can affect the structure and/or function of living tissue via chemical reactions. Drugs can be legal or illegal, addictive (e.g. narcotics), or not addictive. Drugs covered by law are known as “controlled substances”. Taken in excess, these drugs can possibly cause illness or death. Seventy five percent of the evidence to be analyzed in forensic labs is drug-related. Pharmaceutical companies send new drugs to the FBI Crime lab to be categorized for future forensic analysis and comparison. Some drugs standardized in forensic labs include: Marijuana, Cocaine, Methamphetamine, Ecstasy, Ritalin, Heroin, and Lysergic Acid Diethylamide (LSD).

Forensic analyses include organic and inorganic analytical techniques. Color Tests, Chromatography and Immunoassay tests are used in forensic labs. Some of these techniques are based on the solubility of substances in different solvents e.g. Chromatography (a means of separating and identifying organic components). This technique is especially useful in order to distinguish mixtures of illicit drugs, which can contain different substances used to dilute the drug. One of the most precise analytical techniques is Gas Chromatography combined with the mass spectrophotometer, GCMS. The GCMS gives a conclusive individual image (much like a fingerprint) for thousands of different chemical substances, no two of which are alike.

Drugs must be carefully collected, labeled and preserved as forensic evidence for future laboratory and legal analysis, maintaining the “Chain of Custody”. (Saperstein, Ch. 9 p. 228)

Drug recognition Expert: This expert initially categorizes drugs using a microscope. The drugs then undergo further testing. Different types of microscopes can be used to analyze forensic evidence including drugs. These include the compound microscope, comparison microscope, stereoscopic microscope, polarizing microscope, microspectrophotometer, and the Scanning electron microscope (SEM). (Saperstein, pp. 164-174)

Forensic Toxicology includes the analysis of alcohol and drugs. Techniques used in Toxicology include setting up an analytical scheme or series of tests to detect, isolate and identify a specific substance. (p.278, Saperstein)

  1. Drugs can be acidic (barbiturates and aspirin) or basic (phencyclidine, methadone, amphetamines and cocaine) in character. Acidic drugs are extracted with acidic water, basic drugs are extracted with organic solvents e.g. chloroform.
  2. Color Screening Tests: 1. Marquis, 2.Dillie-Koppanyi, 3. Duquenois-Levine, 4.Van Urk, 5. Scott Test. A quick color-screening test using TLC (thin layer chromatography) can indicate the presence of a drug. If positive, then more sensitive and expensive analyses can confirm the actual identity of suspected drugs. Microcrystalline tests can also indicate the presence or absence of a specific drug, but confirmation tests with the GCMS are required to identify the drug.
  3. Confirmation tests for drugs can include spectrophotometry using ultraviolet (UV) and infrared (IR) light The infrared spectrum is unique for each compound and can be considered analogous to a “fingerprint” of that compound. The most powerful analytical tool is the GC/MS, gas chromatography/mass spectrometer, that combines the purification of chromatography with the specificity of a mass spectrometer (See Fig. 10-12 and 10-13 pp. 280-281, Saperstein). In a GCMS, the drug sample passes through the chromatography column which separates all compounds in the sample which are then sent to the mass spectrometer which fragments the compound(s) giving a specific “fingerprint” pattern for each substance. Different compounds can be seen on a print out-as peaks from the GC and fragments from the MS (Saperstein, see fig 5- 9 for heroine and cocaine on p. 254). This GCMS technology allows for detection of very low levels of drugs in the blood or urine
  1. Alcohol tests can determine the concentration of alcohol in the blood or urine is a commonly required analysis. Alcohol concentrations can be determined from the breath or the urine. A Breathalyzer measures a color change produced from the reaction of potassium dichromate with alcohol (p. 268 Saperstein). More accurate blood alcohol levels can be determined by Gas chromatography (see p. 273 Saperstein, fig. 10-9)

Drug use can result in dependence (i.e. addiction), whichcan be physiological and/or psychological. Early laws focused on “habit-forming” drugs like opium and cocaine. These laws classified drugs as Narcotic, Hallucinogenic, Depressant, Stimulant, or Anabolic Steroids.

  1. Narcotics: Morphine, Heroin, Methadone, and Codeine. These are analgesics and relieve pain by depressing the central nervous system.
  2. Depressants: Barbiturates (can be short-acting or long-acting), Alcohol, Methaqualone (Quaalude), Meprobamate (Miltown, equanil), Diazepam (Valium), and Chlordiazepoxide (Librium). These drugs depress the central nervous system.
  3. Stimulants: amphetamines, cocaine (originally used as an anesthetic and painkiller), caffeine, and nicotine. These drugs can result in a high euphoric feeling.
  4. Hallucinogens: Marijuana, Lysergic Acid Diethylamide (LSD), Phencyclidine (PCP), Ecstasy (MDMA, a modified amphetamine), psilocybin, and mescaline. Hallucinogens cause visual, auditory and mood alterations from the norm.
  5. Anabolic Steroids: related to testosterone. These steroids can cause liver cancer, masculinize females and diminish sex drive in males.

Drug-Control Laws categorize drugs according to their addictive nature and whether or not they have medicinal value. Criminal penalties are present at each level from 1-20 years in prison and up to a million dollars in fines. (Saperstein p. 247 for table of Schedule I-V drugs).

References and Resources:

Saperstein, Richard, “Criminalistics: An Introduction to Forensic Science”, Prentice Hall, Inc., Upper Saddle, NJ 07458, 2001. ISBN 0-13-013827-4 (textbook with lots of background information and figures)

Toxin Websites:

CHEMISTRYANALYSIS QUALITATIVE AND QUANTITATIVE websites:

GCMS

gas chromatography originally from from Sam Houston State University

Infrared Analysis: fair site: Univ. of

Mass Spectroscopy: basic information:

Infrared Spectroscopy tutorial:

NMR spectroscopy tutorial:

HPLC Chromatography tutorial: