Analysis of cannabinoids in urine samples of short-term and long-term consumers of hemp seed products

Forensic Sci Int. 2019 Dec;305:109997. doi: 10.1016/j.forsciint.2019.109997. Epub 2019 Oct 21.


With the increasing consumption of hemp seed products, it is important to establish whether biological samples from consumers contain trace cannabinoids that could mistakenly be attributed to cannabis abuse. Thus, we analyzed whether the cannabinoids, 11-nor-9-carboxy-tetrahydrocannabinol, cannabidiol, and cannabinol, can be detected in the urine of short-term (1 week) and long-term (12 weeks) consumers of hemp seed products. Using three hemp seed products that have recently been highly distributed in Korea, subjects consumed 30 g of hemp seeds (Group A, 53.1 (±0.5) μg THC and Group B, 124.81 (±1.5) μg THC) or 2 capsules of hemp seed oil (Group C, 11.1 μg THC) once a day at 10am. In the short-term study, the hemp seed product was consumed for 7 days, after which a single urine sample was collected. In the long-term study, the hemp seed product was consumed for 12 weeks, and urine samples were collected at 7 day intervals. For screening of the urine samples, we used COBAS C311, and for the confirmatory analysis we used gas chromatography/mass spectrometry. In the screening, all 64 samples from the short-term study were below the detection cutoff level of 25 ng/mL. In the long-term study, out of the 480 samples, 3 samples from 2 participants were above the cutoff level, but these samples were all negative in screening. In conclusion, our study demonstrated that when hemp seed products sold in Korea are consumed in normal quantities over the short- or long-term, urine samples do not test positive for cannabinoids.

Keywords: Cannabinoid; GC/MS; Hemp seed; Urine; Δ9-tetrahydrocannabinol carboxylic acid.

MeSH terms

  • Adult
  • Cannabinoids / urine*
  • Cannabis*
  • Case-Control Studies
  • Female
  • Gas Chromatography-Mass Spectrometry
  • Humans
  • Limit of Detection
  • Male
  • Marijuana Abuse / diagnosis
  • Middle Aged
  • Seeds* / chemistry
  • Substance Abuse Detection
  • Urinalysis
  • Young Adult


  • Cannabinoids