An Indiana researcher has developed a new type of test that can determine concentrations of THC, the psychoactive compound in marijuana, rather than its presence alone, potentially introducing a more convenient means for manufacturers to protect consumers from unwanted and potentially illegal amounts of THC in legal CBD products.

The technology improves on existing tests, such as the Duquenois-Levine reagent, which was developed in the 1930s and is the predominant field test to which police currently have access, according to the patent application published May 6 by the U.S. Patent and Trademark Office. Because the Duquenois-Levine test detects only the presence of THC, not its concentration level, it can lead to the arrest of citizens who are in possession of legal products.

"A lot of these things that we're doing have been around for a long time, and we just do them because we've always done that, and they need to be updated," said inventor Charles Steele, a visiting instructor of physical science at Purdue University Northwest. "My goal with this was to make a product that would actually do what's currently needed, because tests that are being done now are not meeting the needs of law enforcement, industry or society as a whole."

According to Steele, with the largest companies being the exception, most manufacturers of CBD and derived products do not have the analytical resources to ensure that their products are within a 0.3% THC limit, as set by the U.S. Food and Drug Administration. Because so many producers cannot test their products precisely, many CBD products that are advertised as THC-free do, in fact, contain the psychoactive compound, partly because, under certain conditions, CBD can become THC.

CBD products — from gummy bears to mouthwash to pain-relief creams — have proliferated in recent years, and the industry is set to grow from $429.4 million to over $1.9 billion within the next five years. 

Steele has witnessed the result of this lack of quality control firsthand. Working with Purdue Northwest's STEM on the Road program, which brings him to northwestern Indiana high schools to foster interest in science, Steele has been introduced, by their arresting officers, to a number of students who had tested positive for THC after using hemp or CBD products they thought were legal. 

A 2020 study showed that 40% of U.S. teens have used CBD products, though other recent research shows that legalizing marijuana will not increase its use among the same demographic. 

One student Steele met through background research on his patent lost a nursing scholarship because she tested positive for THC after using products she thought were free of the compound. 

"It's a personal thing with me. I find kids with good track records who now have a drug possession charge on them because they were going to be cool and smoke hemp flower," Steele said in an interview with The Academic Times. "And — I'm sorry — these things shouldn't ruin your life."

Meeting these students inspired Steele to test about a half-dozen CBD and hemp products in his lab, and all came back positive for THC, despite being marketed as THC-free. A CBD skin cream to ease bursitis pain led the bunch at 7% THC. 

Since then, he has tested 25 different CBD product types, including candies, cigarette paper and toothpaste, with his students. Of all the products that declared themselves THC-free, 50% to 70% returned positive results for the highly regulated compound. 

The first form of the test is a simple setup using two vials. The user places a small sample of testing material into a vial with hydrochloric acid and shakes it up. Then, the user adds a testing solution and shakes the vial again. The resulting mixture will change color, and the intensity of that color change will reflect how much THC the sample contains. While the test has already been licensed by a private company, Steele wants to have his technology verified independently. 

"I've done the work. The licensee has validated it. But from a scientific perspective, the inventor and the guy who's trying to sell it are not really credible to say it works," Steele said.

Steele is now working with a variety of agencies and a major chemical company to validate the test's efficacy. 

The application for the patent, "Portable detection and quantification method for Delta 9 THC," was filed on Nov. 6, 2020, with the U.S. Patent and Trademark Office. It was published May 6 with the application number US2021/0131952. The earliest priority date was Nov. 6, 2019. The inventor of the pending patent is Charles A. Steele, Purdue University Northwest. The assignee is Purdue Research Foundation.