Analysis of (–)-11-nor-9-carboxy-Δ9-tetrahydrocannabinol and (–)-11-nor-9-carboxy-Δ8-tetrahydrocannabinol in hair from a school-age population

• Published in: Journal of analytical toxicology Vol. 49; no. 4; pp. 224 - 230
• Main Authors: Paulsen, Ryan B, Stowe, G. Neil, Schaffer, Michael I, Krohn, Nickolaus
• Format: Journal Article
• Language: English
• Published: England 12.04.2025
• Subjects: Adolescent; Child; Chromatography, Liquid; Dronabinol - analogs & derivatives; Dronabinol - analysis; Female; Hair - chemistry; Humans; Limit of Detection; Male; Substance Abuse Detection - methods; Tandem Mass Spectrometry
• ISSN: 0146-4760; 1945-2403; 1945-2403
• DOI: 10.1093/jat/bkaf020

A sensitive liquid chromatography–tandem mass spectrometry method for the detection of (–)-11-nor-9-carboxy-Δ9-tetrahydrocannabinol and (–)-11-nor-9-carboxy-Δ8-tetrahydrocannabinol in hair with a cutoff of 1 pg/10 mg of hair and a limit of quantitation of 0.2 pg/10 mg of hair for both analytes was developed and is herein described. A subset of samples collected from a school-age population between December 2022 and February 2023 was analyzed using this method after having screened presumptive positive by enzyme immunoassay out of a total pool of approximately 5300 samples. Of these presumptive positive samples, 66% showed the presence of one or both analytes at a concentration ≥1 pg/10 mg of hair. Of the 213 positive samples, 57% contained more (–)-11-nor-9-carboxy-Δ8-tetrahydrocannabinol than (–)-11-nor-9-carboxy-Δ9-tetrahydrocannabinol and 6% contained more than 50-fold higher Δ8 isomer than Δ9 isomer. Of the 197 samples that were reportable for (–)-11-nor-9-carboxy-Δ9-tetrahydrocannabinol ≥1 pg/10 mg cutoff, 53% of them contained more (–)-11-nor-9-carboxy-Δ8-tetrahydrocannabinol than (–)-11-nor-9-carboxy-Δ9-tetrahydrocannabinol. Of the 197 samples that were reportable for (–)-11-nor-9-carboxy-Δ8-tetrahydrocannabinol ≥1 pg/10 mg cutoff, 15.7% exceeded the upper limit of linearity of the method (200 pg/10 mg). These results suggest a high level of (–)-Δ8-tetrahydrocannabinol usage in this population relative to (–)-Δ9-tetrahydrocannabinol usage. They further suggest the possibility that (–)-11-nor-9-carboxy-Δ9-tetrahydrocannabinol reported for some of these samples may only have been present due to (–)-Δ9-tetrahydrocannabinol contamination of (–)-Δ8-tetrahydrocannabinol products being consumed in large quantities. Thus, reported results for (–)-11-nor-9-carboxy-Δ9-tetrahydrocannabinol alone may give a false picture of the extent of the cannabis product being consumed by a test subject.