Original scientific paper
https://doi.org/10.2478/aiht-2019-70-3352
Optimisation of a gas chromatography-mass spectrometry method for the simultaneous determination of tetrahydrocannabinol and its metabolites in rat urine
Nino Fuchs
; University Hospital Centre Zagreb, Croatia
Alena Miljanić
; Department of Biotechnology, University of Rijeka, Croatia
Anja Katić
; Institute for Medical Research and Occupational Health, Zagreb, Croatia
Nataša Brajenović
; Institute for Medical Research and Occupational Health, Zagreb, Croatia
Vedran Micek
; Institute for Medical Research and Occupational Health, Zagreb, Croatia
Radovan Fuchs
; Institute for Medical Research and Occupational Health, Zagreb, Croatia
Irena Brčić Karačonji
orcid.org/0000-0002-1151-8839
; Institute for Medical Research and Occupational Health, Zagreb, Croatia
Abstract
In order to evaluate the effect of irinotecan (IRI) on urinary elimination of delta-9-tetrahydrocannabinol (THC) in a rat experimental model, we developed an analytical method for the determination of the mass concentration of THC and its metabolites [11-hydroxy-delta-9-tetrahydrocannabinol (THC-OH) and 11-nor-9-carboxy-delta-9-tetrahydrocannabinol (THC-COOH)] in the urine of rats treated only with THC and treated simultaneously with THC and irinotecan. For this purpose, hydrolysis and solid phase extraction conditions of the investigated analytes were optimised and a gas chromatography-mass spectrometry (GC-MS) method was developed to determine all three analytes in rat urine. The most effective hydrolysis method for THC, THC-OH, and THC-COOH conjugates was so-called tandem hydrolysis by the β-glucuronidase enzyme from Escherichia coli at 50 °C for 2 hours and followed by alkaline hydrolysis. The proposed method was then applied for determining concentrations of analytes in 24-hour rat urine. THC was not detected in either sample, THC-OH was detected in 50 % of samples, and THC-COOH in all of the samples. Enhanced urinary THC-COOH excretion was noted in rats administered combined treatment compared to single THC treatment. The method described
herein was suitable for determining the mass concentration of THC metabolites in the rat urine due to its sensitivity (detection limits: 0.8-1.0 μg/L), accuracy (>96 %), and precision (RSD <6 %).
Keywords
analytical validation; cannabis; GC-MS; hydrolysis; irinotecan
Hrčak ID:
229441
URI
Publication date:
6.12.2019.
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