title: Investigation of the transformation of 11-nor-9-carboxy-Δ(9)-tetrahydrocannabinol during water chlorination by liquid chromatography-quadrupole-time-of-flight-mass spectrometry.
abstract: The stability of the main metabolite of cannabis, (±)-11-nor-9-carboxy-Δ(9)-tetrahydrocannabinol (THCCOOH), during water chlorination has been investigated. THCCOOH was degraded in few seconds following a pseudo-first order kinetics. Sample pH turned out to be a significant factor, decreasing THCCOOH half-life with an increase in its values. Seven by-products could be positively identified from accurate mass measurements: three compounds resulted from electrophilic substitutions of hydrogen per chlorine (or bromine) in the aromatic ring, whereas the formation of the remaining four involved additional reactions in the C-C double bond (hydration and halogenation). The software predicted toxicity of these products towards Daphnia magna indicates that they are expected to have toxicity values similar or higher than its precursor compound. Experiments conducted with diluted urine showed that THCCOOH was stable in this matrix, probably due to a rapid and complete reaction between chlorine and other organic constituents already present in the samples. In real surface waters, the extent of the reaction was also affected by the organic matter content, and so THCCOOH was rapidly degraded in samples scarcely affected by human activities, being more stable in waters with a higher level of pollution.
authors.affiliation: Department of Analytical Chemistry, Nutrition and Food Sciences, IIAA - Institute for Food Analysis and Research, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
authors.forename: Iria
authors.initials: I
authors.lastname: González-Mariño
authors.forename: Isaac
authors.initials: I
authors.lastname: Rodríguez
authors.forename: José Benito
authors.initials: JB
authors.lastname: Quintana
authors.forename: Rafael
authors.initials: R
authors.lastname: Cela
mesh_terms: D000818:Animals; D002713:Chlorine / Q000737:chemistry*; D002853:Chromatography, Liquid; D003621:Daphnia / Q000187:drug effects; D013759:Dronabinol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000633:toxicity; D054879:Halogenation; D007928:Lethal Dose 50; D013058:Mass Spectrometry / Q000379:methods; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000633:toxicity; D018508:Water Purification
chemical_list: D014874:Water Pollutants, Chemical; D002713:Chlorine; C016780:11-nor-delta(9)-tetrahydrocannabinol-9-carboxylic acid; D013759:Dronabinol
keywords: 11-Nor-9-carboxy-Δ(9)-tetrahydrocannabinol (THCCOOH); Cannabis; Chlorination; Liquid chromatography–mass spectrometry (LC–MS); Time-of-flight (TOF); Transformation products