Drug Chemistry


The Drug Chemistry Section of the crime laboratory analyzes evidence for the presence of cannabis and controlled substances as defined under the Illinois Compiled Statutes, Chapter 720, Acts 550 and 570.


Cannabis plant

The laboratory receives evidence for drug analysis in a variety of forms including plant material, powders, liquids, tablets, capsules and paper. The most common type of drug identified in the laboratory is cannabis (also known as marijuana or pot). The second and third most common drugs identified are cocaine and heroin respectively. Some other drugs commonly encountered in the laboratory include hydrocodone/acetaminophen mixtures (Vicodin®); benzodiazepines e.g. alprazolam (Xanax®), clonazepam (Klonopin®), diazepam (Valium®); hallucinogens including lysergic acid diethylamide (LSD), psilocin (found in “magic mushrooms”); ecstasy-type drugs including 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA); anabolic steroids including testosterone, stanozolol, nandrolone decanoate.


The drug analyst has to first weigh the sample without packaging. This is achieved using an electronic balance. Samples received in the laboratory can be as small as a residue amount that is visible by eye, but not conducive to weighing. They can also be very large.  The laboratory has received on occasion bales of cannabis (about the size of a microwave), and “bricks” of cocaine (about the size of a hard-cover novel).


After weighing the analyst then has to test the sample. At a minimum one preliminary test and one confirmatory test has to be performed to be able to make an identification.


Examples of preliminary testing include color tests – wet chemical testing; microcrystalline tests – using a polarizing light microscope (PLM); ultraviolet-visible spectrophotometry – measuring the absorbance of ultraviolet light by the sample dissolved in a liquid; thin layer chromatography – separating components of a sample on a chemically coated glass plate; gas chromatography – volatilizing a liquid preparation of the sample and separating components of the sample.


Gas Chromatograph-Mass spectrometer (GC-MS)

Confirmatory tests include mass spectrometry – breaking molecules into reproducible fragments

and infrared spectrometry – measuring the degree of transmission of infrared light through a sample. The data produced by both of these methods is called a spectra and is akin to a chemical fingerprint. For an unknown spectra to be identified as a controlled substance it has to be compared to a known standard (purchased from a chemical supplier, with a certificate of authenticity, that has been verified in the laboratory by comparing its spectra to published data before use in case work) run on the same instrument.


For cannabis in the plant material form a microscopical confirmatory test can be performed. This involves examining the unknown substance under a microscope and observing for the presence of distinct morphological features.


On occasion the section receives samples that despite thorough testing are not found to contain a controlled substance. Some examples of commonly identified non-controlled substances include baking soda, soap and vitamins.



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