A Reliable Marijuana Breathalyzer is Near

Driving under the influence of marijuana is illegal no matter which state you’re in. To enforce the law, authorities need a simple, rigorous roadside test for marijuana intoxication.

Although several companies are working to develop marijuana breathalyzers, testing a person’s breath for marijuana-derived compounds is far more complicated than testing for alcohol.
But scientists at the National Institute of Standards and Technology (NIST) have taken an important step toward that goal by measuring a fundamental physical property of the main psychoactive compound in marijuana, delta-9 tetrahydrocannabinol (THC). Specifically, they measured the vapor pressure of this compound—a measurement that, due to the compound’s chemical structure, is very difficult and has not been accomplished before.

One reason it is difficult to design a reliable marijuana breathalyzer is that delta-9 tetrahydrocannabinol (THC), the primary psychoactive compound in marijuana, is a large molecule with a complex structure. Ethyl alcohol is more easily measured with a breathalyzer. In these images, carbon atoms are dark gray, hydrogen atoms are light gray, and oxygen atoms are red. 3D model based on computer rendering, not experimental data.
Credit: Kelly Irvine/NIST

Forensic Chemistry – Determination of Cannabinoid Vapor Pressures to Aid in Vapor Phase Detection of Intoxication

• PLOT-cryo was used to measure the vapor pressures of CBD and Δ9-THC.
• PLOT-cryo stabilizes labile solutes because collection is done at low temperature.
• Vapor pressures were much lower than for compounds with similar molecular weights.

The quest for a reliable means to detect cannabis intoxication with a breathalyzer is ongoing. To design such a device, it is important to understand the fundamental thermodynamics of the compounds of interest. The vapor pressures of two important cannabinoids, cannabidiol (CBD) and Δ9-tetrahydrocannabinol (Δ9-THC), are presented, as well as the predicted normal boiling temperature (NBT) and the predicted critical constants (these predictions are dependent on the vapor pressure data). The critical constants are typically necessary to develop an equation of state (EOS). EOS-based models can provide estimations of thermophysical properties for compounds to aid in designing processes and devices. An ultra-sensitive, quantitative, trace dynamic headspace analysis sampling called porous layered open tubular-cryoadsorption (PLOT-cryo) was used to measure vapor pressures of these compounds. PLOT-cryo affords short experiment durations compared to more traditional techniques for vapor pressure determination (minutes versus days). Additionally, PLOT-cryo has the inherent ability to stabilize labile solutes because collection is done at reduced temperature. The measured vapor pressures are approximately 2 orders of magnitude lower than those measured for n-eicosane, which has a similar molecular mass. Thus, the difference in polarity of these molecules must be impacting the vapor pressure dramatically. The vapor pressure measurements are presented in the form of Clausius-Clapeyron (or van’t Hoff) equation plots. The predicted vapor pressures that would be expected at near ambient conditions (25 °C) are also presented.

5 thoughts on “A Reliable Marijuana Breathalyzer is Near”

  1. I recently had severe headaches that cannot be cured. I tried to find a good medicine for a long time, but to no avail. In the end, the doctor advised me to try CBD oil and it worked for me.

  2. I think that there should be less regulations and law restrictions for CBD hemp flowers, and for those people, who simply want to relax after a hard day at work, consuming some cannabidiol in their stressed body. Talking of which, where do you usually get CBD stuff, especially hemp flowers? I mean online resources. I've heard a lot of good reviews about this shop ( here: https://blacktiecbd.net/collections/cbd-hemp-flowers ) called Black Tie. And after some exploring of their CBD stuff and prices, for now I can say for sure, that they have pretty awesome quality / price ratio of all cannabidiol goods.

  3. CBD oil is relatively new but is quickly gaining ground and becoming a huge topic of discussion and debate in the world of natural and self treatments. Many people hear about these products being discussed, even within mainstream media sources, but remain confused as to how they operate and what effects they have on the body. Since there is much misinformation on the internet about the topic, we hope this article has answered your question, “What is the difference between CBD oil and marijuana? Because of these calming versus stimulating effects, CBD also seems to be incredibly useful for the reduction of anxiety. The cannabis plant has flowering buds and is typically grown for THC extraction or so that the various parts of the plant can be dried up and smoked. Hemp is an entirely different plant, although in the same family, and it is typically used for the production of clothing, ropes, and other materials, as well as lotions and other cosmetics or skin care items. Cannabis and hemp plants differ greatly in the amounts of THC they contain. Even within the world of cannabis plants as a whole, you will find very different levels of THC in certain strains of marijuana versus others. THC is a cannabinoid just like CBD is, but with opposing effects within the body. This is where the biggest differences come in between the two. Hemp is naturally very high in CBD and very low in THC. Cannabis is the opposite, being very high in THC and very low in CBD.

Comments are closed.