In July of 2019, Virginia became the first US state to acquire a new drug test created by a team of forensic chemists in Switzerland. The 4-AP test, or “Cannabis Typification” or “Swiss Test,” purports to be able to help differentiate between hemp– a legal variety of cannabis– and marijuana. However, laboratory documentation says that the test is not approved for testimony and cannot determine the concentration of THC.
The test is of interest as a potential tool for law enforcement to determine whether a sample should be submitted to the state’s forensic crime laboratory for further instrumental analysis to determine the THC concentration. The test may be helpful as a screening mechanism to rule out further testing of samples that are likely hemp. It cannot positively identify a sample as marijuana because it does not measure the concentration of THC, but instead is a ratio test.
Like other preliminary drug tests currently in use, the 4-AP test is a color test, which is performed by mixing a small sample of the substance to be tested (which will have been predetermined to be some form of cannabis using another approved field test) with a chemical reagent. The mixture is then monitored for changes in color– blue indicates the presence of a high volume of THC, consistent with marijuana, while a pink color indicates a lower volume of THC, meaning the substance is more likely to be hemp. A more complete description of how the tests work, including instructional videos, is available here, on the Virginia Department of Forensic Science’s website.
While Virginia was the first to acquire the test, other states, including Florida, have shown interest using the 4-AP test. American law enforcement continues to explore the limitations of the test, but as the use of hemp/CBD products for therapeutic purposes continues to rise, the possibility of a test which could differentiate between those legal products and a controlled substance may be of interest to both the legal and law enforcement communities seeking to prevent the wrongful charges being brought against individuals possessing legal hemp products.