Does Liquid Chromatography/Mass Spectrometry (LC/MS) testing for cannabis only detect delta-9-tetrahydrocannabinol (delta-9-THC)?

From the Guidelines

LC/MS testing for marijuana does not only test for delta-9-THC, as it can also detect other cannabinoids and metabolites, including 11-nor-9-carboxy-THC (THC-COOH), depending on the test configuration. The test's specificity relies on the laboratory's protocol and the purpose of the testing, allowing for the detection of multiple cannabinoids simultaneously, such as delta-8-THC, CBD, CBN, and other THC isomers 1.

Key Points to Consider

• LC/MS methods are highly sensitive and specific, enabling the differentiation between various cannabinoids based on their unique molecular structures and fragmentation patterns.
• The primary metabolite tested for is 11-nor-9-carboxy-THC (THC-COOH), which remains in the body longer than delta-9-THC itself.
• Modern LC/MS testing can be designed to detect multiple cannabinoids, providing a more comprehensive analysis of cannabis use.
• It is essential to understand that most comprehensive drug testing programs will use methods capable of identifying multiple cannabis compounds, not just delta-9-THC, as noted in a study published in The Lancet Child and Adolescent Health 1.

Implications for Testing

• The ability of LC/MS testing to detect various cannabinoids and metabolites has significant implications for drug testing programs, particularly in the context of cannabis use.
• The test's configuration and the laboratory's protocol play a crucial role in determining the specificity and sensitivity of the results.
• As cannabis contains more than 140 pharmacologically active cannabinoids, the most prominent of which is Δ⁹-tetrahydrocannabinol (THC), LC/MS testing can provide valuable insights into cannabis use and its effects on the body 1.

From the Research

LC/MS Testing for Marijuana

• LC/MS testing for marijuana does not only test for delta-9 THC, but can also detect other cannabinoids and metabolites, such as delta-8 THC, 11-hydroxy-THC, and 11-nor-9-carboxy-THC 2, 3, 4.
• The testing method can vary, with some studies using liquid chromatography-tandem mass spectrometry (LC-MS/MS) to separate and quantify different cannabinoids and their metabolites 2, 3, 4.
• The sensitivity and specificity of LC/MS testing can be higher than other methods, such as enzyme-linked immunosorbent assay (ELISA), allowing for the detection of cannabinoids in smaller concentrations 5.

Detection of Cannabinoids

• LC/MS testing can detect a range of cannabinoids, including:

• Delta-9 THC 2, 6, 3, 4, 5
• Delta-8 THC 3, 4
• 11-hydroxy-THC 2, 4, 5
• 11-nor-9-carboxy-THC 2, 4, 5
• Cannabidiol (CBD) 2, 5
• Cannabigerol (CBG) 5

• The limits of detection and quantification can vary depending on the testing method and the specific cannabinoid being detected 2, 3, 4, 5.

Method Validation

• LC/MS testing methods can be validated using various techniques, such as method validation data and measurement uncertainty calculations 6.
• The validation of LC/MS testing methods is important to ensure the accuracy and reliability of the results 6, 4.