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Many Delta-8 THC Products Contain Non-Compliant Levels of Delta-9 THC. Do Yours? Find Out With Orthogonal Methods

ByTrichome Team

June 8, 2021

Reading Time: 4 minutes

Delta-8 THC is a trending topic in the headlines (again), and we’ve gotten several questions from cultivators and processors about properly detecting it and levels of delta-9 THC. We’ve explored delta-8 in the past—what it is, why it’s popular—and now, we’ll discuss ways to ensure accuracy in testing for it and other cannabinoids. 

For products containing isomerized delta-8 THC, using the correct confirmation analysis is essential in identifying delta-9 THC contamination. To help you understand what’s in play, we’ll explore how leveraging gas chromatography-mass spectrometry (GC-MS) can be employed side-by-side with existing high performance liquid chromatography (HPLC) methods to bring the highest level of confidence in a delta-8 THC product result.

Although GC-MS is typically reserved for other types of analyses such as checking for pesticide residues, it is regularly employed by forensic drug laboratories for the differentiation between hemp and high-THC cannabis—and when you’re trying to ensure your product is compliant, that kind of assurance is key. 

How Labs Test for Cannabinoids and Contaminants

Cannabis testing labs have an array of equipment that is employed to test for various potencies and contaminants in THC cannabis and hemp crops, as well as derivative products. For example, we use HPLC for cannabinoid analysis, gas chromatography for terpene analysis and inductively coupled plasma (ICP) for heavy metals. The industry norm is to employ a single analytical method for these routine potency and contaminant samples, and for good reason: Labs can ensure accurate testing results by using validated methods along with established testing technologies operated by qualified staff under a robust quality management program. 

However, there are some instances where greater confidence in a result is needed, and so more than one analytical method is used. These additional methods are often referred to as orthogonal methods, or more simply, confirmation analysis or complementary analysis. Industries that commonly employ these orthogonal analyses include pharmaceutical drug discovery companies and forensics labs—but they can be extremely useful in cannabinoid type and potency testing too.

Orthogonal Methods, Explained

Forensics labs employ what is referred to as screening and confirmatory analyses for positive drug identification when dealing with certain controlled substances. For something like differentiation of low-THC hemp from high-THC cannabis, for example, screening analysis includes methods that may be easily employed at low cost, such as a color test, while confirmation is achieved by more powerful lab methods, such as GC-MS, as specified in the DEA’s analysis of drugs manual. The pharmaceutical industry employs orthogonal methods as well and goes to great lengths to ensure compounds are identified accurately. 

These two areas of testing have a critical impact on people’s lives, and confidence in a result has to be extremely high when the stakes include prosecution for a criminal offense or bringing a previously unknown drug to market.

Orthogonal testing isn’t about one more powerful method overruling the result of a less powerful method. Rather, it’s about both methods reaching the same conclusion, therefore resulting in a higher level of confidence. This is particularly the case when the two methods rely on different mechanisms to arrive at that conclusion. This type of thinking is employed in science all the time. 

To illustrate, let’s apply orthogonal methods to calculate the distance you travel on your daily commute home from work. You first determine the distance traveled in your car based on the mileage displayed on your dashboard. This data comes from your vehicle’s odometer, which documents mileage based on the number of times the wheel rotates and the circumference of your tire. 

Then, you pull up your phone’s GPS app and calculate the distance, which is a method that uses satellite triangulation. If each method—your odometer and your GPS—gives you the same number of miles traveled, you can be highly confident in the result. Here’s why: The two measurements have relied on completely different mechanisms to measure distance traveled. The chances of those two measuring systems coming up with the same number by mistake is extremely low. 

While the above example is clearly overkill in the need to know vehicle mileage, in the previously mentioned areas of forensics and drug discovery, orthogonal testing or confirmation analysis is expected and the norm.

Testing Cannabis for Delta-8 and Delta-9 THC 

At Trichome Analytical, we think that the testing of delta-8 products is just as critical, and can benefit from the orthogonal method. This is especially true when it comes to determination of delta-9 THC in products. 

Despite the ongoing ambiguity over the legal status of delta-8, federal law is very clear that delta-9 THC is a controlled substance—the sale of products containing greater than 0.3% THC (outside of a state-regulated high-THC market) is illegal. So, how can orthogonal testing methods be applied to the analysis of delta-8 products to better identify delta-9 THC?

The first thing to know is that this level of testing is rarely, if ever, performed on routine cannabis samples. However, after what we and many others are seeing in the industry, we don’t think delta-8 samples are routine. Recall from our previous blog post how delta-8 and delta-9 THC differ by the position of a single molecular bond in their structure, and how a host of other THC isomers is often present in these products, making identification difficult. In keeping with the validated analytical method in the DEA handbook for drug identification, which is for differentiation between low-THC hemp and high-THC cannabis, and updated based on the Agricultural Improvement Act of 2018, we feel GC-MS should be used as an orthogonal method to the typical HPLC analysis. 

GC-MS is specified in the DEA handbook for differentiation between low- and high-THC cannabis, and it is a truly orthogonal method compared to HPLC analysis, which labs already employ widely for cannabinoid testing. One method uses gas, the other uses liquid. One method uses UV light absorbance detection, while the other detects based on mass. Going back to the example of measuring mileage in your car, these two test methods use different mechanisms of identification to test the same thing. 

One might ask why GC-MS analysis is not performed on all cannabis samples for cannabinoids if it is so good at identification, and mentioned by the DEA. The answer is that it is not so optimal to characterize the wide range of cannabinoids required because of the process of decarboxylation that takes place as a result of the GC-MS method. This is another reason why coupling HPLC with GC-MS makes sense and how the two analysis types can complement each other. 

To round out our discussion about GC-MS and orthogonal testing, below is an example of what you will find on Trichome Analytical COAs for GC-MS analysis of cannabinoids, and how to interpret these results.