Conversion of 7-Carboxy-Cannabidiol (7-COOH-CBD) to 11-Nor-9-Carboxy-Tetrahydrocannabinol (THC-COOH) during Sample Preparation for GC-MS Analysis
The growing use of cannabidiol (CBD) products by the general public is expected to result in an increase in the prevalence of CBD and the CBD metabolites in drug testing laboratories. CBD converts into tetrahydrocannabinol (THC) under acid conditions which could produce false-positive results, but little is known about how the presence of the urinary metabolite of CBD, 7-carboxy-cannabidiol (7-COOH-CBD), would affect urine drug testing for 11-nor-9-carboxy-tetrahydrocannabinol (THC-COOH). As the operators of the National Laboratory Certification Program (NLCP), we prepared a set of performance testing samples containing 7-COOH-CBD for cannabinoid testing at the laboratories accredited by the NLCP to investigate if 7-COOH-CBD can produce false-positive results for THC-COOH during immunological screening analysis and if 7-COOH-CBD can be converted to THC-COOH. At concentrations up to 2,500 ng/mL, 7-COOH-CBD was not reactive by immunoassay in any of the four different immunoassay kits used. Additionally, we did not observe any significant conversion of 7-COOH-CBD to THC-COOH in assays used by NLCP-certified laboratories. However, we did see conversion when we requested that selected laboratories retest their samples using derivatization with perfluorinated anhydrides in combination with perfluorinated alcohols or when samples containing 7-COOH-CBD were exposed to acid for an extended time.
© The Author(s) 2021. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: [email protected]
Coulter C, Wagner JR. Coulter C, et al. J Anal Toxicol. 2021 Sep 17;45(8):807-812. doi: 10.1093/jat/bkab074. J Anal Toxicol. 2021. PMID: 34137890
Vikingsson S, Winecker RE, Cone EJ, Kuntz DJ, Dorsey B, Jacques M, Senter M, Flegel RR, Hayes ED. Vikingsson S, et al. J Anal Toxicol. 2022 Mar 9:bkac013. doi: 10.1093/jat/bkac013. Online ahead of print. J Anal Toxicol. 2022. PMID: 35260906
Andrenyak DM, Moody DE, Slawson MH, O’Leary DS, Haney M. Andrenyak DM, et al. J Anal Toxicol. 2017 May 1;41(4):277-288. doi: 10.1093/jat/bkw136. J Anal Toxicol. 2017. PMID: 28069869 Free PMC article.
Hill VA, Schaffer MI, Paulsen RB, Stowe GN. Hill VA, et al. J Anal Toxicol. 2022 May 20;46(5):487-493. doi: 10.1093/jat/bkab068. J Anal Toxicol. 2022. PMID: 34153110
How ZT, Gamal El-Din M. How ZT, et al. Environ Pollut. 2021 Jan 1;268(Pt A):115642. doi: 10.1016/j.envpol.2020.115642. Epub 2020 Sep 14. Environ Pollut. 2021. PMID: 33032096 Free PMC article. Review.
Can CBD show up on a drug test?
Workers who use a lot of CBD (cannabidiol) for pain, anxiety, insomnia, or a host of other symptoms, can accidentally (and unfairly) fail drug tests for cannabis in certain cases, media and experts report.
“We are aware of a few reports of CBD users who have flunked a drug test,” said Dale Gieringer, co-director of California NORML.
‘We are aware of a few reports of CBD users who have flunked a drug test.’
Dale Gieringer, co-director, California NORML
In the most common workplace drug screen—a urine test—employers aren’t looking for CBD, because CBD has never been found to impair judgment or motor skills. Instead, workers fail workplace drug testing for marijuana’s main active ingredient, THC, which can exist in low amounts in some CBD products and then persist in the human body for weeks.
A CBD product’s label might misstate the amount of THC, depending on the market in which you’re shopping. State-licensed adult-use and medical cannabis stores are regulated and mandate product testing, but outside of those systems, CBD product quality can vary in a largely unregulated market. Tests of CBD products from unlicensed stores have come back positive for THC.
“It’s caveat emptor,” said Barry Sample, Ph.D., senior director of science and technology for employer solutions at the nation’s biggest drug testing company, Quest Diagnostics. “The real issue is, how do you trust the labeling?”
Furthermore, if you consume enough CBD—on the order of 1,000 milligrams a day of CBD—just the residual THC could put your test results in the danger zone. This is a big deal because a failed drug test can result in the denial of loss of both job and income, and can also lead individuals to lose access to important resources like education and welfare benefits, child custody, and prescriptions for pain medication.
Can you fail a drug test for CBD oil ? Not really, but sort of
You won’t fail a drug test for CBD, but you could potentially fail a drug test for any residual THC in that CBD product.
Sample said Quest Diagnostics does not test for CBD. THC, however, is on the lengthy list of drugs they test for.
How do drug tests for cannabis work
Here’s how drug tests work. Employers collect and send off samples—largely urine—to drug testing companies who run them through a machine that can measure trace chemicals in the liquid. Technicians look for evidence of a byproduct of THC, the main active cannabinoid in cannabis — not CBD. (More rarely, employers may test saliva, hair, or blood from their employees. We’ll get to that in a minute.)
One key guideline is drug-testing rules for federal employees. A federal worker will fail a drug test if their urine tests positive for any more than a trace amount of the THC metabolite (THC-COOH). And by “trace,” we mean just 50 billionths of a gram per milliliter of urine (50 ng/ml).
THC is the most common reason a worker fails a drug test. Some 2.3% of all US drug tests came back positive for cannabis use in 2018.
Watch out for old tech
There’s also the potential that an older, not uncommon type of analytical method falsely identifies THC in a sample that only contains CBD. That method is gas-chromatography mass-spectrometry with the derivatization agent trifluoroacetic anhydride (TFAA). Tens of thousands of false positives might stem from the error annually, reporter Amanda Chicago-Lewis estimates, but at least there is some recourse—CBD users have successfully challenged a failed drug test for THC if the lab used this specific method, which can result in a false report of CBD as THC.
Why is there THC in my CBD oil?
The cannabis plant produces both THC and CBD. Medical cannabis and industrial hemp are cousins—both create dozens of similar compounds called cannabinoids.
So CBD from “federally legal” hemp can still consist of up to 0.3% THC. If you ingest very high doses of CBD—in the thousands of milligrams per day—from federally legal hemp oil, that means you may also be ingesting at least 1 mg of THC as well.
“If you’re liberal with your hemp CBD oil use, you could hypothetically test positive for THC,” said Greg Gerdeman, Ph.D., chief science officer at Colorado’s United Cannabis, makers of Prana Hemp and Prana Medicinals.
Many times, labels are just plain wrong, too. Outside of state-licensed systems, no mandatory oversight exists, said Martin Lee, co-founder and director of Project CBD.
“Mislabeled CBD products proliferate outside the licensed cannabis marketplace,” Lee said. “Some CBD products labeled as ‘THC-free’ aren’t what the label says. If a CBD user tests positive for THC, either the test is inaccurate or, more likely, the no-THC product contained some THC.”
Avoid accidental THC exposure by using state-licensed and tested CBD products. Depending on the state, CBD products can be thoroughly tested and the labels are accurate. If the label says there’s no THC in there, it’s probably true.
How much CBD will make me fail a drug test?
Again, it’s not the CBD. But flunking a THC drug test because you took CBD depends on the source of your CBD, how much you took, over how long, your metabolism, and other factors like hydration levels.
Full spectrum CBD vs. broad spectrum CBD vs. CBD isolates: Consider your CBD oil’s source
A pure “isolate” of just the CBD molecule, which is commercially available, should not contain any THC. However, these isolates are extracted from hemp oil, and are of varying quality. By law, federally legal hemp oil can have up to 0.3% THC in it. Sometimes that number is higher, because of variations in test results.
Other factors that could result in failing a drug test
Beyond your CBD source, dosage, length of use, personal chemistry, and other factors determine drug test success or failure.
At one end, someone who smokes high-THC cannabis every day and then stops can still fail a drug test more than a month later. That’s because the human body stores THC in fat cells and burns it into THC-COOH later, Sample said.
At the other end, you could theoretically take CBD hemp oil for months, at low amounts (50 mg/day), and never fail a urine screen for THC-COOH. It’s not clear how much CBD hemp oil is needed—or for how long—to end up with more than 50 ng/ml of THC-COOH in your urine. But certainly, if you’re taking large amounts of CBD, depending on the source, you could test positive for THC.
“Any time THC enters the body, you have the possibility of having it stored in the fat cells and slowly released,” said Sample.
How to pass a drug test for CBD
You won’t get drug tested for CBD—you’ll be drug tested for THC. If you’re concerned for any reason, you may consider following the detoxification guidelines for THC, including discontinuing use, dieting, exercise, and staying hydrated to get trace THC out of your system.
How long does CBD stay in your system?
CBD effects last 90 minutes to several hours, depending on how it is consumed. The body turns CBD into the byproduct CBD-COOH in a matter of hours, and then it sticks around for at least several days. But it doesn’t matter, because no employer is testing for CBD-COOH.
Does CBD show up on a mouth swab test?
Mouth swabs don’t check for CBD—again, they’re checking for THC, said Sample. So no, CBD won’t show up on a standard workplace drug test mouth swab. THC will, though, so keep off large amounts of CBD with trace levels of THC.
Oral fluid testing is uncommon. In 2018, general workforce testing included over 6 million urine screens, versus just 1.3 million oral fluid tests, and 200,000 hair follicle tests.
“Almost all” of those specimens are tested for THC-COOH, Dr. Sample said.
Does CBD show up in a hair follicle test?
Stop us if you’ve heard this one, but workplace hair follicle tests are generally not checking for CBD—they’re checking for that old standby THC-COOH. So no, CBD won’t show up on a standard workplace drug test of a hair follicle. THC will, though. Any CBD you took that had trace levels of THC could leave THC byproducts in a hair follicle, where they have the potential to stick around for a while. Hair follicles can contain a months-long record of drug use, depending on the length of the hair.
Can stomach acid turn CBD into THC?
You might have read rumors online that stomach acid can turn CBD into THC. That’s possible but unlikely, according to the experts we consulted.
CBD water marketers have trumpeted this claim lately to sell CBD water over other forms of CBD, said Gerdeman at United Cannabis, which makes and sells wholesale CBD isolate.
Multiple human trials of large doses of oral CBD have never resulted in the detection of THC in the blood plasma of test subjects—so if it’s happening outside of a lab beaker, no one’s proved it. Dr. Ethan Russo debunked the stomach acid theory in Trends in Pharmacological Sciences forum article Cannabidiol Claims and Misconceptions.
At-home CBD drug testing kits
Leafly does not know of any at-home CBD drug testing kits, or why you’d take one. If you’re worried about failing a workplace drug test, you could take an at-home THC-COOH test, though accuracy varies among these products.
What’s the future of CBD drug testing?
The trend is toward less drug testing for non-safety jobs. More and more states are ending discrimination against use of THC. Federal bills like the MORE Act are following suit.
Does Using CBD Hemp Oil Result in a Positive Drug Test for THC or Marijuana?
This article is sponsored by PlusCBD Oil, a product line from CV Sciences (formerly CannaVest). CV Sciences is one of the leading suppliers and manufacturers of agricultural hemp-derived CBD bulk and finished products.
Whether you agree with it in principle or not, testing for illicit drug use is a reality for many workers in the United States. Drug testing is mandatory for federal employees, and although it isn’t required in the private sector, more employers are implementing some kind(s) of drug screening.
When drug testing is mandated, employers almost always follow the SAMHSA (Substance Abuse and Mental Health Services Administration) guidelines because it puts them on solid legal ground. Typically, there is an overlap between testing guidelines and accepted cutoff levels for drugs and drug metabolites in confirmatory testing and screening.
Because THC is widely recognized as being responsible for marijuana’s psychoactivity and euphoria, a routine urine drug screen for marijuana use consists of an immunoassay with antibodies that are made to detect it, and its main metabolite, 11-nor-delta9-caboxy-THC (THC-COOH). SAMHSA has set the cutoff level for a positive urine screen in the immunoassay at 50 ng/mL. When the immunoassay screen is positive at the > 50 ng/mL level, a confirmatory GC/MS (Gas Chromatography/Mass Spectrometry) test is performed to verify the positive urine screen. The confirmatory GC/MS has a cutoff level of 15 ng/mL and is specific only to the 11-nor-THCCOOH metabolite.
Does CBD Show Up on a Drug Test?
Fortunately, the urine drug screen for THC-COOH is known to have very little cross-reactivity to other cannabinoids that are not intoxicating, such as CBD (cannabidiol), CBG (cannabigerol), CBN (cannabinol), and others. This is good news for “normal” consumers of CBD/hemp oil.
That said, individuals using unusually large doses of a cannabinoid-rich hemp oil product (above 1000-2000 mg of hemp oil daily) could theoretically test positive during the initial urinary screen. Although very rare, the urine screen in these cases would likely represent a “false positive” due to other non-THC metabolites or compounds, which may cross-react with the immunoassay. When this is the case, the confirmatory GC/MS test would be negative, since CBD and other cannabinoids will not be detected by the more accurate (and specific) GC/MS screen.
Keep in mind that most of the high-quality, reliable CBD-rich hemp oil products contain much less THC than marijuana. For example, hemp contains anywhere from 1/10th to 1/300th of the THC concentration found in marijuana. An individual consuming 1000-2000 mg per day of hemp oil would thus consume approximately 3-6 mg of THC. This exceedingly high dose may result in detection of positive urine screen in up to 11% to 23% of assays.
On the other hand, there is some data demonstrating that at daily doses of 0.5mg of THC from 3-5 servings of most commercial CBD-rich hemp oil products, the positive urine screen rate is < 0.2%. Again, most servings of typical high-quality, high-purity CBD-based hemp oil products contain well below 0.1mg of THC and therefore have over 400-600 times less THC than marijuana products.
What does all this mean? Put simply, a consumer who uses a high-quality, scientifically vetted hemp-based product at the standard serving size is highly unlikely to test positive for THC and/or THC-COOH. However, it’s important to be cognizant that extremely high doses may result in a positive urine screen (that would be subsequently shown to be false via GC/MS). Ultimately, consumers need to be fully informed of the specific regulations posed by their employers and adjust their consumption of cannabinoid products accordingly.
Note: Most research suggests that for infrequent or ‘non-daily’ users of cannabis, a typical high-dose marijuana cigarette (containing about 40mg to 50mg of THC) would result in a positive THC metabolite screen for up to two days at this cutoff level. However, for routine and regular users of cannabis, this same screen could be positive for weeks, but this depends on many factors including, but not limited to:
- how much and how often cannabis is used
- the metabolism of individual being tested
- the route of administration
- other factors such as medications used, liver or kidney disease, etc.
This article is based on SAMHSA standards. Other organizations’ drug testing standards may vary, so keep in mind that the findings presented in this article may differ under alternative standards. If you have any concern about testing positive for THC when using CBD-containing hemp oil, please seek advice from your health care professional.
Gustafson RA, Kim I, Stout PR, Klette KL, George MP, Moolchan ET, Levine B, Huestis MA. Urinary pharmacokinetics of 11-nor-9-carboxy-delta9-tetrahydrocannabinol after controlled oral delta9-tetrahydrocannabinol administration. J Anal Toxicol. 2004 Apr; 28(3):160-7
Gustafson RA, Levine B, Stout PR, Klette KL, George MP, Moolchan ET, Huestis MA. Urinary cannabinoid detection times after controlled oral administration of delta9-tetrahydrocannabinol to humans. Clin Chem. 2003 Jul; 49(7):1114-24.
Kemp PM, Abukhalaf IK, Manno JE, Manno BR, Alford DD, Abusada GA. Cannabinoids in humans. I. Analysis of delta 9-tetrahydrocannabinol and six metabolites in plasma and urine using GC-MS. J Anal Toxicol. 1995 Sep; 19(5):285-91.
Huestis MA, Mitchell JM, Cone EJ. Urinary excretion profiles of 11-nor-9-carboxy-delta 9-tetrahydrocannabinol in humans after single smoked doses of marijuana. J Anal Toxicol. 1996 Oct;20(6):441-52.
Wall ME, Perez-Reyes M. J Clin Pharmacol. The metabolism of delta 9-tetrahydrocannabinol and related cannabinoids in man. 1981 Aug-Sep; 21(8-9 Suppl):178S-189S.