Using an MRM method on a GC-triple quadrupole MS to confirm and quantitate THC in oral fluid is an effective alternative to blood and urine samples.

Marijuana is the most widely used illegal drug in the United States. Each year U.S. law enforcement agencies apprehend over two million pounds of marijuana in various forms. Initial evidence is first submitted to forensic laboratories and screened for marijuana by microscopic inspection and simple chemical tests. The identification of cannabinoids must then be confirmed as showing positive. Oral fluid analysis is growing in popularity as an alternative to blood and urine analysis for delta-9-tetrahydrocannabinol (THC) detection. Oral fluid can be analyzed without the embarrassment of urine sample analysis or the pain incurred by blood analysis. Similarly, oral fluid analysis necessitates much less training in comparison with the extensive training required for blood analysis. Due to the low concentration of THC normally found in oral fluid and the low volume of oral fluid readily available for this type of analysis, oral fluid analysis is not, however, without its challenges.

This article discusses the regulatory guidelines in the U.S. for the analysis of THC, examines alternative methods used for this type of analysis, and demonstrates how a forensics crime laboratory uses a triple stage quadruople GCMS/ MS system for the confirmation and quantitation of THC in an oral fluid matrix.

The Drug
Marijuana is the world’s most commonly used illicit drug. Although marijuana contains a minimum of 400 different chemicals, the main active chemical is THC. The membranes of certain nerve cells in the brain contain protein receptors that bind to THC.Once securely in place, THC sparks a series of cellular reactions that ultimately lead to the euphoric high that users experience when they smoke marijuana. Marijuana has also been proven to produce a sedative effect.¹

Recent studies have shown that the usage of marijuana directly increases the users’ susceptibility to certain brain, heart, and lung diseases. THC has also been proven to impair the immune system’s ability to fight disease. Data released by the National Survey on Drug use and Health in 2007 noted that 14.4 million Americans aged 12 or older used marijuana at least once in the month prior to being surveyed.

Short-term effects of marijuana include problems with memory and learning, distorted perception, difficulty in thinking and problem solving, loss of coordination, and increased heart rate. Research for long-term marijuana usage indicates changes in the brain similar to those seen after long-term abuse of other major drugs. For example, cannabinoid (THC or synthetic forms of THC) withdrawal in chronically exposed animals leads to an increase in the activation of the stress-response system and changes in the activity of nerve cells containing dopamine. Dopamine neurons are vital to the regulation of motivation and reward and are directly or indirectly affected by all drugs of abuse.²