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What kind of results can be expected from forensic drug chemistry?
The results of chemical analysis performed on submitted samples will yield a report that contains details about the materials submitted, the analysis that was performed and the results of that analysis. This report generally contains the total weight of the sample, the individual components within the sample, and the amount of each component found. Often, the report will identify the schedule of any illegal substances found in the sample.
What are the limitations of the analysis?
The main limiting factor in forensic drug chemistry is the size and condition of the sample. If the sample collected does not contain enough material to be accurately measured and tested, then the analysis would be limited and the results may be inconclusive. For example, investigators may collect a piece of fabric with a suspicious stain and send it for analysis. There is no way for the analyst to accurately measure the weight of the material soaked into the fabric, thus the total amount of the substance will be unknown. However, the analyst can determine if there is an illegal substance present and the concentration of the substance.
Improperly packaged materials present a similar problem for analysts. For example, plant material such as marijuana or mushrooms that has been packaged improperly may become degraded before analysis can be performed. In cases of improperly packaged samples, destruction of the material can significantly reduce the amount of the sample available for analysis. Learn more about Crime Scene Investigation ▸
How is quality control and quality assurance performed?
To ensure the most accurate analysis of evidence, the management of forensic laboratories puts in place policies and procedures that govern facilities and equipment, methods and procedures, and analyst qualifications and training. Depending on the state in which it operates, a crime laboratory may be required to achieve accreditation to verify that it meets quality standards. There are two internationally recognized accrediting programs in the U.S. focused on forensic laboratories: The American Society of Crime Laboratory Directors Laboratory Accreditation Board and ANSI-ASQ National Accreditation Board / FQS.
In addition to these, individual laboratories have specific policies and procedures that govern the way analysis is performed in the lab. The Scientific Working Group for the Analysis of Seized Drugs (SWGDRUG) publishes recommendations for the analysis and quality control of forensic laboratories performing chemical analysis. This includes proper evidence handling and control, calibration of the instruments used, documentation methods, materials handling and storage, analytical and verification procedures, report writing and case review. These recommendations are available online.
What information does the report include and how are the results interpreted?
Once the sample material is analyzed, the information is included into a report that provides the submitting agency with details about the sample including the components contained and the quantities of each component. In some cases, particularly federal cases, the report will also contain the purity of the illegal substances found in the sample. Guidelines set forth by SWGDRUG recommend a report contain the following information:
- Laboratory and submitting agency information
- Description of all items and samples submitted. Ex: One brick-shaped package of compressed white powder, Several round, red tablets marked ABC, One plastic page containing compressed plant material
- Results of the analysis. Ex: Powder was analyzed and found to contain cocaine HCl. Net Weight: 1024.6 ± 1.2 grams (95% confidence level).
- Tests/Techniques: weight determination, Gas Chromatography/Mass Spectrometry (GC/MS), Fourier Transform Infrared Spectroscopy (FTIR)
- Analyst signature
- Dates of submittal and analysis
- Any remarks from the analyst
View a sample report from SWGDRUG.
Are there any misconceptions or anything else about forensic drug chemistry that would be important to the non-scientist?
All controlled substances are not illegal, and all drugs are not controlled substances. There is a general misconception that controlled substances and illegal drugs are the same thing. This is not the case—many drugs are controlled substances with perfectly legitimate uses. For example, not all narcotics are illegal. Many are legal with a prescription from a doctor. However, narcotics possessed or used without a valid prescription are considered illegal substances. Drugs that have been scheduled by the government usually pose a danger with improper use. Some drugs are scheduled because they have no legitimate use and pose a serious threat when used at all, such as LSD or MDMA.
There are also many illegal drugs that are not controlled substances. This stems from the rapidly changing synthetic drug trade, which includes substances such as “bath salts.” Manufacturers change the chemical formulas for these drugs often and market them as “not for human consumption” to circumvent existing drug laws. However, these substances are highly dangerous and law makers are working to draft legislation to control these substances.
TV crime drama vs. courtroom testimony The detective on television who smells or tastes an unknown substance and declares, “it’s heroin” is doing something that would be very dangerous in real life. Drugs cannot be identified by smell, taste, appearance or other visual characteristics. Only properly performed chemical analysis by qualified analysts can determine the composition of a substance. The TV detective who tastes the strange white powder is not only contaminating evidence, he may also end up inadvertently poisoning himself in the process.
Television crime dramas often portray chemical analysis as a quick process that can often be performed right at the scene. This is absolutely not the case. The colorimetric and other field devices used by law enforcement do not provide full chemical analysis. Handheld devices that use lasers to detect chemical signatures are becoming more common; however, these instruments provide only presumptive testing and do not stand up to the requirements for admission in court. Analysts presenting testimony in court must present validated results that include the quality control methods used in the lab, calibration and quality control methods performed on the instruments used in the analysis, the education and training of the analyst, and the instrument maintenance and cleaning performed prior to analysis. Instruments used in the field by law enforcement cannot meet these rigorous requirements and thus can only provide presumptive results.