title: Cannabis Use Surveillance by Sweat Analysis.
abstract: Sweat testing, an alternative matrix for establishing drug abuse, offers additional benefits to the more common biological samples. The authors developed a procedure using gas chromatography-mass spectrometry to test for Δ9-tetrahydrocannabinol, 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid, cannabinol (CBN), and cannabidiol (CBD) in a sweat patch. The results were compared with urine and hair sample results.
  
  
  
  Urine, hair, and sweat samples were simultaneously collected from 12 patients who were involved, respectively, in forensic case and monitoring abuse. Selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), recovery, intraday and interday imprecision, and inaccuracy of the quantification procedure were validated. LODs in hair were 0.05 ng/mg for Δ9-tetrahydrocannabinol, CBN, and CBD, and 0.005 ng/mg for 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid. The LOD for sweat was 0.30 ng/patch for all substances. The LOQ in hair was 0.1 ng/mg for Δ9-tetrahydrocannabinol, CBN, and CBD, and 0.01 ng/mg for 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid. The LOQ was 0.4 ng/patch in sweat for each analyte. Cannabinoid in urine was determined by means of immunochemical screening (cutoff 11-nor-Δ-tetrahydrocannabinol-9-carboxylic acid 50 ng/mL).
  
  
  
  All subjects tested positive for 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid and Δ9-tetrahydrocannabinol in urine and hair. In sweat samples, Δ9-tetrahydrocannabinol was found in all patches (0.4-2.0 ng/patch); 6 cases were positive for CBN (0.4-0.5 ng/patch) and 3 for CBD (0.4-0.6 ng/patch); 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid was never detected in patches.
  
  
  
  Present sweat analysis results integrated the information from hair and urine and showed that sweat analysis is a suitable, noninvasive method for monitoring compliance with rehabilitation therapy and for detecting recent cumulative use of cannabinoids.
authors.affiliation: *Department of Surgical and Biomedical Science, Forensic Medicine, Forensic Science and Sports Medicine Section, University of Perugia, Perugia, Italy; and †Legal Medicine Section, Public Health Institute, Sacred Heart Catholic University, Rome, Italy.
authors.forename: Cristiana
authors.initials: C
authors.lastname: Gambelunghe
authors.forename: Nadia
authors.initials: N
authors.lastname: Fucci
authors.forename: Kyriaki
authors.initials: K
authors.lastname: Aroni
authors.forename: Mauro
authors.initials: M
authors.lastname: Bacci
authors.forename: Antonio
authors.initials: A
authors.lastname: Marcelli
authors.forename: Riccardo
authors.initials: R
authors.lastname: Rossi
mesh_terms: D000293:Adolescent; D000328:Adult; D002185:Cannabidiol / Q000032:analysis*; D002187:Cannabinol / Q000032:analysis*; D013759:Dronabinol / Q000031:analogs & derivatives* / Q000032:analysis*; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006197:Hair / Q000737:chemistry; D006801:Humans; D057230:Limit of Detection; D008297:Male; D008875:Middle Aged; D015813:Substance Abuse Detection / Q000379:methods*; D013542:Sweat / Q000737:chemistry*; D014556:Urine / Q000737:chemistry; D055815:Young Adult
chemical_list: D002185:Cannabidiol; C009411:delta(6)-tetrahydrocannabinol-7-oic acid; D013759:Dronabinol; D002187:Cannabinol